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Wang J, Yin B, Liu G, Li S, Zhang X, Hu Z, Wu W, Zhang Y. Microhardness distribution of the tibial diaphysis and test site selection for reference point indentation technique. Medicine (Baltimore) 2019; 98:e16523. [PMID: 31335730 PMCID: PMC6708845 DOI: 10.1097/md.0000000000016523] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Indentation hardness test is a good in vitro method of bone quality assessment. The purpose of this study is to explore the distribution characteristics of bone tissue microhardness in tibial diaphysis and provide theoretical support for the test site selection of the reference point indentation technique.Three fresh right tibias were obtained from 3 cadaver donors. The tibial diaphysis was evenly divided into 6 sections. Bone specimens with a thickness of 3 mm were cut from each part. After appropriate management, micro-indentation tests were performed in various regions of the specimens to acquire the microhardness values of the tibial diaphysis. Statistical analysis was performed by randomized block design variance analysis to study the distribution characteristics of bone microhardness.72 regions were selected for 360 effective indentations. We found that the bone microhardness is inhomogeneous in tibia diaphysis. Mean hardness value of the anterior, medial, posterior, lateral region of tibia diaphysis was 45.58 ± 4.39 Vickers hardness (HV), 52.33 ± 3.93 HV, 54.00 ± 4.21 HV, 52.89 ± 4.44 HV, respectively. The anterior cortex exhibits lower microhardness value than the other regions (P < .001). Within the same region, microhardness varies significantly with positions in the tibial diaphysis. The variations in indentation hardness are bound to have a significant impact on the comparability of different reference point indentation (RPI) studies.The results of this study indicated the regional microhardness difference in the human tibia diaphysis. The microhardness of different planes in the same region is also inconsistent. Inhomogeneous distribution of indentation microhardness would have considerable influence in the test site selection of RPI technique. The data collected in our study would contribute to the design of highly precise 3D printing implants and bionic bones with gradient elastic modulus.
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Affiliation(s)
- Jianzhao Wang
- Department of Orthopaedic Surgery, The Third Hospital of Hebei Medical University
- Key Laboratory of Biomechanics of Hebei Province, Shijiazhuang, Hebei, P.R. China
| | - Bing Yin
- Department of Orthopaedic Surgery, The Third Hospital of Hebei Medical University
- Key Laboratory of Biomechanics of Hebei Province, Shijiazhuang, Hebei, P.R. China
| | - Guobin Liu
- Department of Orthopaedic Surgery, The Third Hospital of Hebei Medical University
- Key Laboratory of Biomechanics of Hebei Province, Shijiazhuang, Hebei, P.R. China
| | - Sheng Li
- Department of Orthopaedic Surgery, The Third Hospital of Hebei Medical University
- Key Laboratory of Biomechanics of Hebei Province, Shijiazhuang, Hebei, P.R. China
| | - Xiaojuan Zhang
- Department of Orthopaedic Surgery, The Third Hospital of Hebei Medical University
- Key Laboratory of Biomechanics of Hebei Province, Shijiazhuang, Hebei, P.R. China
| | - Zusheng Hu
- Department of Orthopaedic Surgery, The Third Hospital of Hebei Medical University
- Key Laboratory of Biomechanics of Hebei Province, Shijiazhuang, Hebei, P.R. China
| | - Weiwei Wu
- Department of Orthopaedic Surgery, The Third Hospital of Hebei Medical University
- Key Laboratory of Biomechanics of Hebei Province, Shijiazhuang, Hebei, P.R. China
| | - Yingze Zhang
- Department of Orthopaedic Surgery, The Third Hospital of Hebei Medical University
- Key Laboratory of Biomechanics of Hebei Province, Shijiazhuang, Hebei, P.R. China
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Punathil S, Pulayath CV, Ismail SP, Bavabeedu SS, Moyin S, Uthappa R. Assessment of Enamel Surface Microhardness with different Fluoride Varnishes-An In Vitro Study. J Contemp Dent Pract 2018; 19:1317-1321. [PMID: 30602634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
AIM This study aimed to assess the microhardness of the enamel surface after fluoride varnish application. MATERIALS AND METHODS Thymol of 0.1% in distilled water was used to store the collected healthy sixty teeth. The samples were divided into three groups randomly as per the different applica -tion of fluoride varnish. Group A: Fluor protector varnish (FIV) application, group B: Duraphat varnish application and group C: Bifluorid 10 varnish application. The present study followed the pH cycling protocol. Microhardness tester was used to test the microhardness of enamel surface and was expressed as micro-hardness measurements of Vickers hardness number (VHN) which was performed at baseline, on the 3rd day andon 7th day. RESULTS At baseline, group A samples mean SMH value was 230.64 ± 12.32 which was slightly more than group B with 229.45 ± 10.22 and group C with 230.10 ± 11.45. There was no significant difference showed with the analysis of variance between the groups. On the 3rd day, there was a slight increase in the mean SMH in group A with 235.39 ± 6.44 and no significant difference between the groups was seen statistically. On the 7th day, the group A showed high SMH value of 262.20 ± 4.89 compared to other groups which didn't show a significantly high statistical difference. CONCLUSION On conclusion, post-application of fluorprotector varnish showed higher enamel surface microhardness compared to Duraphat and Bifluorid 10 varnishes. CLINICAL SIGNIFICANCE In young children, fluoride varnishes are effectively used as a noninvasive, anti-caries agent in the treatment of initial caries. Therefore, in routine dental practice, the knowledge about different fluoride varnishes is of importance.
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Affiliation(s)
- Sameer Punathil
- Department of Pediatric and Preventive Dentistry, Sree Anjaneya Institute of Dental Sciences, Calicut, Kerala, India, Phone: +919526227454, e-mail:
| | - Civy V Pulayath
- Department of Public Health Dentistry, Malabar Dental College and Research Centre, Edappal, Kerala, India
| | - Siraj P Ismail
- Department of Public Health Dentistry, Pariyaram Dental College, Pariyaram, Kannur Kerala, India
| | - Shashit S Bavabeedu
- Restorative Dental Sciences, King Khalid University College of Dentistry, Abha, Kingdom of Saudi Arabia
| | - Shabna Moyin
- Department of Conservative Dentistry and Endodontics, Sree Anjaneya Institute of Dental Sciences, Calicut, Kerala, India
| | - Roshan Uthappa
- Department of Restorative Dental Sciences, College of Dentistry, Majmaah University, Al Zulfi, Kingdom of Saudi Arabia
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Makuch AM, Skalski KR. Human cancellous bone mechanical properties and penetrator geometry in nanoindentation tests. Acta Bioeng Biomech 2018; 20:153-164. [PMID: 30520440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
PURPOSE The goal of the study was to determine the influence of the penetrator geometry on the human cancellous bone mechanical properties in indentation tests. The aim of this research was also the assessment of the material properties of bone structures, having in mind the energy aspects of the curve obtained in the cycle: inelastic loading and elastic unloading. METHODS The samples were resected from a femoral heads of patients qualified for a hip replacement surgery. During the Depth Sensing Indentation tests, hardness and elastic modulus of the cancellous bone tissue were measured using the spherical and Vickers penetrators. Measurements were made in a node and in a trabecula for each sample. RESULTS The analysis of the measurement results and the calculations of total energy, i.e., elastic and inelastic, and those of the parameters of hardness and elasticity made it possible to assess the influence of the penetrator geometry on the mechanical properties of bone structures at a microscopic level. CONCLUSIONS It was found, with respect to the methodology of indenta- tion, that without determining the shape of the penetrator and the site of the indentation, an objective assessment of the micro mechanical properties of the tested material is not possible.
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Affiliation(s)
- Anna M Makuch
- Institute of Precision Mechanics, Departament of Mechanical Properties, Warsaw, Poland
| | - Konstanty R Skalski
- Institute of Precision Mechanics, Departament of Mechanical Properties, Warsaw, Poland
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Abstract
Noninvasive measurement of tissue viscoelastic properties is gaining more attention for screening and diagnostic purposes. Recently, measuring dynamic response of tissue under a constant force has been studied for estimation of tissue viscoelastic properties in terms of retardation times. The essential part of such a test is an instrument that is capable of creating a controlled axial force and is suitable for clinical applications. Such a device should be lightweight, portable, and easy to use for patient studies to capture tissue dynamics under external stress. In this paper, we present the design of an automated compression device for studying the creep response of materials with tissue-like behaviors. The device can be used to apply a ramp-and-hold force excitation for a predetermined duration of time and it houses an ultrasound probe for monitoring the creep response of the underlying tissue. To validate the performance of the device, several creep tests were performed on tissue-mimicking phantoms, and the results were compared against those from a commercial mechanical testing instrument. Using a second-order Kelvin-Voigt model and surface measurement of the forces and displacements, retardation times T1 and T2 were estimated from each test. These tests showed strong agreement between our automated compression device and the commercial mechanical testing system, with an average relative error of 2.9% and 12.4%, for T1 and T2, respectively. Also, we present the application of compression device to measure local retardation times for four different phantoms with different size and stiffness.
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Biały M, Adamczyk W, Gnat R, Stranc T. Tissue Deformation Index as a Reliable Measure of Lateral Abdominal Muscle Activation on M-Mode Sonography. J Ultrasound Med 2017; 36:1461-1467. [PMID: 28339131 DOI: 10.7863/ultra.16.07045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/30/2016] [Indexed: 05/24/2023]
Abstract
The aim of this article is to present a novel method of evaluating the activity of lateral abdominal muscles using M-mode sonography. The method leads to calculation of the tissue deformation index, representing the percent change in lateral abdominal muscle thickness over time. The objectives of this study were as follows: (1) to establish the mean tissue deformation index values for individual lateral abdominal muscles; and (2) to establish the reliability of the tissue deformation index. In a group of 34 healthy young volunteers (mean age, 24.03 years; body mass, 68.89 kg; body height, 174.25 cm), the reflex response of the lateral abdominal muscles to postural perturbation in the form of rapid arm abduction was recorded in 2 series, with 6 repetitions each, and the tissue deformation index was calculated. The mean tissue deformation index values formed a gradient, increasing from deep to superficial lateral abdominal muscles: 0.06%/ms for transversus abdominis, 0.11%/ms for oblique internal, and 0.16 for oblique external muscles. The tissue deformation index values differed significantly among individual lateral abdominal muscles (all paired comparisons, P < .001). Three repeated measurements are sufficient to achieve good intra-rater reliability of the tissue deformation index (intraclass correlation coefficient, > 0.8).
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Affiliation(s)
- Maciej Biały
- Faculty of Physiotherapy, Motion Analysis Laboratory, Jerzy Kukuczka Academy of Physical Education, Katowice, Poland
| | - Wacław Adamczyk
- Institute of Psychology, Pain Research Group, Jagiellonian University, Krakow, Poland
| | - Rafael Gnat
- Faculty of Physiotherapy, Motion Analysis Laboratory, Jerzy Kukuczka Academy of Physical Education, Katowice, Poland
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Mikamori M, Gotoh K, Takahashi H, Akita H, Tomokuni A, Kobayashi S, Ohue M, Fujiwara Y, Yano M, Ishikawa O, Sakon M. Novel intraoperative use of the "Tensipresser" to assess factors predictive of pancreatic fistula after pancreaticoduodenectomy. Surg Today 2017; 47:1201-1207. [PMID: 28324164 DOI: 10.1007/s00595-017-1509-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 02/06/2017] [Indexed: 02/07/2023]
Abstract
PURPOSES Pancreatic fistula (PF) is a challenging complication of pancreaticoduodenectomy (PD). 'Soft pancreas' is reported as a risk factor for PF; however, palpation by the surgeon is not an objective method of evaluating pancreatic texture. We conducted this study to investigate whether a texture analyzer called a "Tensipresser" can be used to quantify pancreatic tissue hardness and predict the development of postoperative PF. METHODS We assessed pancreatic texture in 85 patients who underwent PD. After surgeons assessed the texture of the pancreas subjectively, the physical properties were measured on the pancreatic margin intraoperatively, by the two-bite method using the "Tensipresser". The incidence and severity of PF were based on the definitions of the International Study Group on Pancreatic Fistula. RESULTS Symptomatic PF (grade B and C) developed in 16% of the patients. Patients were divided into two groups based on the Tensipresser measurement: those with a soft and fragile pancreas with hardness < 2070 gw/cm2 and cohesiveness < 0.65 (SF group); and all other patients (non-SF group). In the univariate and multivariate analysis, a small pancreatic duct diameter (<4 mm), no conduction of preoperative chemoradiation therapy, and inclusion in the SF group were significant predictors of PF. CONCLUSION The Tensipresser can evaluate pancreatic texture objectively, helping to define intraoperatively, those at risk of the development of PF.
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Affiliation(s)
- Manabu Mikamori
- Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Nakamichi 1-3-3, Higashinari-ku, Osaka, 537-0025, Japan
- Department of Gastroenterological Surgery, Graduate School of Medicine Osaka University, Yamadaoka 2-2, Suita, Osaka, 565-0871, Japan
| | - Kunihito Gotoh
- Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Nakamichi 1-3-3, Higashinari-ku, Osaka, 537-0025, Japan.
- Department of Gastroenterological Surgery, Graduate School of Medicine Osaka University, Yamadaoka 2-2, Suita, Osaka, 565-0871, Japan.
| | - Hidenori Takahashi
- Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Nakamichi 1-3-3, Higashinari-ku, Osaka, 537-0025, Japan
| | - Hirofumi Akita
- Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Nakamichi 1-3-3, Higashinari-ku, Osaka, 537-0025, Japan
| | - Akira Tomokuni
- Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Nakamichi 1-3-3, Higashinari-ku, Osaka, 537-0025, Japan
| | - Shogo Kobayashi
- Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Nakamichi 1-3-3, Higashinari-ku, Osaka, 537-0025, Japan
| | - Masayuki Ohue
- Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Nakamichi 1-3-3, Higashinari-ku, Osaka, 537-0025, Japan
| | - Yoshiyuki Fujiwara
- Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Nakamichi 1-3-3, Higashinari-ku, Osaka, 537-0025, Japan
| | - Masahiko Yano
- Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Nakamichi 1-3-3, Higashinari-ku, Osaka, 537-0025, Japan
| | - Osamu Ishikawa
- Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Nakamichi 1-3-3, Higashinari-ku, Osaka, 537-0025, Japan
| | - Masato Sakon
- Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Nakamichi 1-3-3, Higashinari-ku, Osaka, 537-0025, Japan
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Chandler JH, Mushtaq F, Moxley-Wyles B, West NP, Taylor GW, Culmer PR. Real-Time Assessment of Mechanical Tissue Trauma in Surgery. IEEE Trans Biomed Eng 2017; 64:2384-2393. [PMID: 28237916 DOI: 10.1109/tbme.2017.2664668] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE This work presents a method to assess and prevent tissue trauma in real-time during surgery. BACKGROUND Tissue trauma occurs routinely during laparoscopic surgery with potentially severe consequences. As such, it is crucial that a surgeon is able to regulate the pressure exerted by surgical instruments. We propose a novel method to assess the onset of tissue trauma by considering the mechanical response of tissue as it is loaded in real-time. METHODS We conducted a parametric study using a lab-based grasping model and differing load conditions. Mechanical stress-time data were analyzed to characterize the tissue response to grasps. Qualitative and quantitative histological analyses were performed to inspect damage characteristics of the tissue under different load conditions. These were correlated against the mechanical measures to identify the nature of trauma onset with respect to our predictive metric. RESULTS Results showed increasing tissue trauma with load and a strong correlation with the mechanical response of the tissue. Load rate and load history also showed a clear effect on tissue response. The proposed method for trauma assessment was effective in identifying damage. The metric can be normalized with respect to loading rate and history, making it feasible in the unconstrained environment of intraoperative surgery. SIGNIFICANCE This work demonstrates that tissue trauma can be predicted using mechanical measures in real-time. Applying this technique to laparoscopic tools has the potential to reduce unnecessary tissue trauma and its associated complications by indicating through user feedback or actively regulating the mechanical impact of surgical instruments.
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Makuch AM, Skalski KR, Pawlikowski M. The influence of the cumulated deformation energy in the measurement by the DSI method on the selected mechanical properties of bone tissues. Acta Bioeng Biomech 2017; 19:79-91. [PMID: 28869620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
PURPOSE The goal of the study was to determine the influence of DSI test conditions, i.e., loading/unloading rates, hold time, and the value of the maximum loading force on selected mechanical properties of trabecular bone tissue. METHODS The test samples were resected from a femoral head of a patient qualified for a hip replacement surgery. During the DSI tests hardness (HV, HM, HIT) and elastic modulus (EIT) of trabecular bone tissue were measured using the Micro Hardness Tester (MHT, CSEM). RESULTS The analysis of the results of measurements and the calculations of total energy, i.e., elastic and inelastic (Wtotal, Welastic, Winelastic) and those of hardness and elasticity made it possible to assess the impact of the process parameters (loading velocity, force and hold time) on mechanical properties of bone structures at a microscopic level. CONCLUSIONS The coefficient k dependent on the EIT/HIT ratio and on the stored energy (ΔW = Wtotal - Welastic) is a measure of the material reaction to the loading and the deformation of tissue.
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Affiliation(s)
| | | | - Marek Pawlikowski
- Institute of Mechanics and Printing, Warsaw University of Technology, Poland
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Łagan SD, Liber-Kneć A. Experimental testing and constitutive modeling of the mechanical properties of the swine skin tissue. Acta Bioeng Biomech 2017; 19:93-102. [PMID: 28869629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
PURPOSE The aim of the study was an estimation of the possibility of using hyperelastic material models to fit experimental data obtained in the tensile test for the swine skin tissue. METHODS The uniaxial tensile tests of samples taken from the abdomen and back of a pig was carried out. The mechanical properties of the skin such as the mean Young's modulus, the mean maximum stress and the mean maximum elongation were calculated. The experimental data have been used to identify the parameters in specific strain-energy functions given in seven constitutive models of hyperelastic materials: neo-Hookean, Mooney-Rivlin, Ogden, Yeoh, Martins, Humphrey and Veronda-Westmann. An analysis of errors in fitting of theoretical and experimental data was done. RESULTS Comparison of load -displacement curves for the back and abdomen regions of skin taken showed a different scope of both the mean maximum loading forces and the mean maximum elongation. Samples which have been prepared from the abdominal area had lower values of the mean maximum load compared to samples from the spine area. The reverse trend was observed during the analysis of the values of elongation. An analysis of the accuracy of model fitting to the experimental data showed that, the least accurate were the model of neo- -Hookean, model of Mooney-Rivlin for the abdominal region and model of Veronda-Westmann for the spine region. CONCLUSIONS An analysis of seven hyperelastic material models showed good correlations between the experimental and the theoretical data for five models.
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Affiliation(s)
- Sylwia D Łagan
- Institute of Applied Mechanics, Cracow University of Technology, Cracow, Poland
| | - Aneta Liber-Kneć
- Institute of Applied Mechanics, Cracow University of Technology, Cracow, Poland
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Gawlak D, Mańka-Malara K, Mierzwińska-Nastalska E, Gieleta R, Kamiński T, Łuniewska M. A comparison of impact force reduction by polymer materials used for mouthguard fabrication. Acta Bioeng Biomech 2017; 19:89-95. [PMID: 28552930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
PURPOSE The essential function of mouthguards is protection against the effects of injuries sustained during sports activities. This purpose will be successfully achieved if appropriate materials ensuring sufficient reduction of the injury force are used for mouthguard fabrication. OBJECTIVE The objective of the study was to investigate the force reduction capability of selected materials as well as to identify which material reduces the impact force to the highest degree. METHODS The material for the study were samples of polymers (6 samples in total), obtained during the process of deep pressing (2 samples), flasking (3 samples) and thermal injection (1 sample), which were tested for impact force damping using an impact device - Charpy impact hammer. The control group comprised of the ceramic material samples subjected to the hammer impact. The statistical analysis applied in this study were one-way Welch ANOVA with post-hoc Games-Howell pairwise comparisons. RESULTS The test materials reduced the impact force of the impact hammer to varying degrees. The greatest damping capability was demonstrated for the following materials: Impak with 1:1 powder-to-liquid weight ratio polymerized with the conventional flasking technique, and Corflex Orthodontic used in the thermal injection technique of mouthguard fabrication. CONCLUSIONS Impak with 1:1 weight ratio and Corflex Orthodontic should be recommended for the fabrication of mouthguards since they demonstrated the most advantageous damping properties.
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Affiliation(s)
- Dominika Gawlak
- Department of Prosthodontics, Faculty of Medicine and Dentistry, Medical University of Warsaw, Warsaw, Poland
| | - Katarzyna Mańka-Malara
- Department of Prosthodontics, Faculty of Medicine and Dentistry, Medical University of Warsaw, Warsaw, Poland
| | | | - Roman Gieleta
- Department of Mechanics and Applied Computer Science, Faculty of Mechanical Engineering, Military University of Technology in Warsaw, Warsaw, Poland
| | - Tomasz Kamiński
- Department of Oral Surgery, Faculty of Medicine and Dentistry, Medical University of Warsaw, Warsaw, Poland
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Nguyen AV, Nyberg KD, Scott MB, Welsh AM, Nguyen AH, Wu N, Hohlbauch SV, Geisse NA, Gibb EA, Robertson AG, Donahue TR, Rowat AC. Stiffness of pancreatic cancer cells is associated with increased invasive potential. Integr Biol (Camb) 2016; 8:1232-1245. [PMID: 27761545 PMCID: PMC5866717 DOI: 10.1039/c6ib00135a] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Metastasis is a fundamentally physical process in which cells are required to deform through narrow gaps as they invade surrounding tissues and transit to distant sites. In many cancers, more invasive cells are more deformable than less invasive cells, but the extent to which mechanical phenotype, or mechanotype, can predict disease aggressiveness in pancreatic ductal adenocarcinoma (PDAC) remains unclear. Here we investigate the invasive potential and mechanical properties of immortalized PDAC cell lines derived from primary tumors and a secondary metastatic site, as well as noncancerous pancreatic ductal cells. To investigate how invasive behavior is associated with cell mechanotype, we flow cells through micron-scale pores using parallel microfiltration and microfluidic deformability cytometry; these results show that the ability of PDAC cells to passively transit through pores is only weakly correlated with their invasive potential. We also measure the Young's modulus of pancreatic ductal cells using atomic force microscopy, which reveals that there is a strong association between cell stiffness and invasive potential in PDAC cells. To determine the molecular origins of the variability in mechanotype across our PDAC cell lines, we analyze RNAseq data for genes that are known to regulate cell mechanotype. Our results show that vimentin, actin, and lamin A are among the most differentially expressed mechanoregulating genes across our panel of PDAC cell lines, as well as a cohort of 38 additional PDAC cell lines. We confirm levels of these proteins across our cell panel using immunoblotting, and find that levels of lamin A increase with both invasive potential and Young's modulus. Taken together, we find that stiffer PDAC cells are more invasive than more compliant cells, which challenges the paradigm that decreased cell stiffness is a hallmark of metastatic potential.
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Affiliation(s)
- Angelyn V Nguyen
- Department of Integrative Biology and Physiology, University of California, Los Angeles, USA.
| | - Kendra D Nyberg
- Department of Integrative Biology and Physiology, University of California, Los Angeles, USA. and Department of Bioengineering, University of California, Los Angeles, USA
| | - Michael B Scott
- Department of Integrative Biology and Physiology, University of California, Los Angeles, USA.
| | - Alia M Welsh
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, USA
| | - Andrew H Nguyen
- Department of General Surgery, University of California, Los Angeles, USA
| | - Nanping Wu
- Department of General Surgery, University of California, Los Angeles, USA
| | - Sophia V Hohlbauch
- Asylum Research, an Oxford Instruments Company, Santa Barbara, California, USA
| | - Nicholas A Geisse
- Asylum Research, an Oxford Instruments Company, Santa Barbara, California, USA
| | - Ewan A Gibb
- Canada's Michael Smith Genome Sciences Centre, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - A Gordon Robertson
- Canada's Michael Smith Genome Sciences Centre, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - Timothy R Donahue
- Department of General Surgery, University of California, Los Angeles, USA and Jonsson Comprehensive Cancer Center, University of California, Los Angeles, USA
| | - Amy C Rowat
- Department of Integrative Biology and Physiology, University of California, Los Angeles, USA. and Department of Bioengineering, University of California, Los Angeles, USA and Jonsson Comprehensive Cancer Center, University of California, Los Angeles, USA
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Wang FC, Jin ZM, McEwen HMJ, Fisher J. Microscopic asperity contact and deformation of ultrahigh molecular weight polyethylene bearing surfaces. Proc Inst Mech Eng H 2016; 217:477-90. [PMID: 14702985 DOI: 10.1243/09544110360729117] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effect of the roughness and topography of ultrahigh molecular weight polyethylene (UHMWPE) bearing surfaces on the microscopic contact mechanics with a metallic counterface was investigated in the present study. Both simple sinusoidal roughness forms, with a wide range of amplitudes and wavelengths, and real surface topographies, measured before and after wear testing in a simple pin-on-plate machine, were considered in the theoretical analysis. The finite difference method was used to solve the microscopic contact between the rough UHMWPE bearing surface and a smooth hard counterface. The fast Fourier transform (FFT) was used to cope with the large number of mesh points required to represent the surface topography of the UHMWPE bearing surface. It was found that only isolated asperity contacts occurred under physiological loading, and the real contact area was only a small fraction of the nominal contact area. Consequently, the average contact pressure experienced at the articulating surfaces was significantly higher than the nominal contact pressure. Furthermore, it was shown that the majority of asperities on the worn UHMWPE pin were deformed in the elastic region, and consideration of the plastic deformation only resulted in a negligible increase in the predicted asperity contact area. Microscopic asperity contact and deformation mechanisms may play an important role in the understanding of the wear mechanisms of UHMWPE bearing surfaces.
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Affiliation(s)
- F C Wang
- School of Engineering, Design and Technology, University of Bradford, Bradford, UK
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Abstract
Biomechanical tissue properties have been hypothesized to play a critical role in the quantification of prosthetic socket production for individuals with limb amputation. In this investigation, a novel indenter platform is presented and its performance evaluated for the purposes of residual-limb tissue characterization. The indenter comprised 14 position- and force-controllable actuators that circumferentially surround a biological residuum to form an actuator ring. Each indenter actuator was individually controllable in position ( [Formula: see text] accuracy) and force (330 mN accuracy) at a PC controller feedback rate of 500 Hz, allowing for a range of measurement across a residual stump. Data were collected from 162 sensors over an EtherCAT fieldbus to characterize the mechanical hyperviscoelastic tissue response of two transtibial residual-limbs from a study participant with bilateral amputations. At five distinct anatomical locations across the residual-limb, force versus deflection data-including hyperviscoelastic tissue properties-are presented, demonstrating the accuracy and versatility of the multi-indenter platform for residual-limb tissue characterization.
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Abstract
Cell contraction force plays an important role in wound healing, inflammation,angiogenesis and metastasis. This study describes a novel method to quantify single cell contraction force in vitro using human aortic adventitial fibroblasts embedded in a collagen gel. The technique is based on a depth sensing nano-indentation tester to measure the thickness and elasticity of collagen gels containing stimulated fibroblasts and a microscopy imaging system to estimate the gel area. In parallel, a simple theoretical model has been developed to calculate cell contraction force based on the measured parameters. Histamine (100 mM) was used to stimulate fibroblast contraction while the myosin light chain kinase inhibitor ML-7 (25 mM) was used to inhibit cell contraction. The collagen matrix used in the model provides a physiological environment for fibroblast contraction studies. Measurement of changes in collagen gel elasticity and thickness arising from histamine treatments provides a novel convenient technique to measure cell contraction force within a collagen matrix. This study demonstrates that histamine can elicit a significant increase in contraction force of fibroblasts embedded in collagen,while the Young's modulus of the gel decreases due to the gel degradation.
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Maske TT, Brauner KV, Nakanishi L, Arthur RA, van de Sande FH, Cenci MS. An in vitro dynamic microcosm biofilm model for caries lesion development and antimicrobial dose-response studies. Biofouling 2016; 32:339-348. [PMID: 26905384 DOI: 10.1080/08927014.2015.1130824] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Some dynamic biofilm models for dental caries development are limited as they require multiple experiments and do not allow independent biofilm growth units, making them expensive and time-consuming. This study aimed to develop and test an in vitro dynamic microcosm biofilm model for caries lesion development and for dose-response to chlorhexidine. Microcosm biofilms were grown under two different protocols from saliva on bovine enamel discs for up to 21 days. The study outcomes were as follows: the percentage of enamel surface hardness change, integrated hardness loss, and the CFU counts from the biofilms formed. The measured outcomes, mineral loss and CFU counts showed dose-response effects as a result of the treatment with chlorhexidine. Overall, the findings suggest that biofilm growth for seven days with 0.06 ml min(-1) salivary flow under exposure to 5% sucrose (3 × daily, 0.25 ml min(-1), 6 min) was suitable as a pre-clinical model for enamel demineralization and antimicrobial studies.
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Affiliation(s)
- T T Maske
- a Graduate Program in Dentistry , Federal University of Pelotas , Pelotas-RS , Brazil
| | - K V Brauner
- a Graduate Program in Dentistry , Federal University of Pelotas , Pelotas-RS , Brazil
| | - L Nakanishi
- a Graduate Program in Dentistry , Federal University of Pelotas , Pelotas-RS , Brazil
| | - R A Arthur
- b Department of Preventive and Community Dentistry , Federal University of Rio Grande do Sul , Porto Alegre-RS , Brazil
| | - F H van de Sande
- a Graduate Program in Dentistry , Federal University of Pelotas , Pelotas-RS , Brazil
- c School of Dentistry , IMED Faculdade Meridional , Passo Fundo-RS , Brazil
| | - M S Cenci
- a Graduate Program in Dentistry , Federal University of Pelotas , Pelotas-RS , Brazil
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Wen K, Li F. [Experimental study on the corrosion behavior of a type of oral near β-type titanium alloys modified with double glow plasma nitriding]. Zhonghua Kou Qiang Yi Xue Za Zhi 2015; 50:751-754. [PMID: 26887401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
OBJECTIVE To study the electrochemical corrosion performance of a type of biomedical materials near beta titanium alloy(Ti-3Zr-2Sn-3Mo-25Nb, TLM) in artificial saliva before and after nitride changing, and to provide clinical basis for clinical application of titanium alloy TLM. METHODS The double glow plasma alloying technology was used to nitride the surface of titanium alloy TLM. The surface properties of the modified layer were observed and tested by optical microscope, scanning electron microscope, glow discharge spectrum analyzer, X-ray diffraction and micro hardness tester. Then, electrochemical measurement system was used to test and compare titanium alloy TLM's electrochemical corrosion in artificial saliva before and after its surface change. Finally, the surface morphology of the original titanium alloy and the modified layer was compared by scanning electron microscope. RESULTS By the technology of double glow plasma nitriding, the surface of the titanium alloy TLM had been successfully nitrided with a modified layer of 4-5 µm in thickness, uniform and compact. Its main compositions were Ti and Ti(2)N. The Microhardness of modified layer also had been improved from (236.8 ± 5.4) to (871.8 ± 5.2) HV. The self-corrosion potential in electrochemical corrosion tests had been increased from -0.559 V to -0.540 V, while the self- corrosion current density had been reduced from 2.091 × 10(-7) A/cm(2) to 7.188 × 10(-8) A/cm(2). Besides, alternating-current impedance(AC Impedance) had also been increased. With the scanning electron microscope, it's obvious that the diameter of corrosion holes on modified layer were approximately 10 µm. As to the diameter and number of corrosion holes on modified layer, they had been decreased comparing with the original titanium alloy. CONCLUSIONS The type of near beta titanium alloy TLM can construct a nitriding modified layer on its surface. Meanwhile, the performance of its anti- corrosion in artificial saliva has been improved, comparing to the original titanium alloy TLM.
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Affiliation(s)
- Ke Wen
- Deparment of Prosthodontics, Affiliated People's Hospital, Shanxi Medical University, Taiyuan 030012, China
| | - Fenglan Li
- Deparment of Prosthodontics, Affiliated People's Hospital, Shanxi Medical University, Taiyuan 030012, China;
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Liu Y, Deng H, Tang L, Zhang Z. [Effect of resin infiltration on microhardness of artificial caries lesions]. Zhonghua Kou Qiang Yi Xue Za Zhi 2015; 50:737-741. [PMID: 26887398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
OBJECTIVE To compare the changes of enamel surface and cross-sectional microhardness of artificial caries immediately and after the twice demineralization through coating resin infiltration, fluoride varnish and fissure sealant. METHODS A total of forty bovine lower incisors enamel samples with artificial caries lesions by the demineralization liquid were used in the experiment. The specimens were then randomly divided into four groups as group A(resin infiltration), B(fluoride varnish), C (fissure sealant), D(control), 10 specimens in each group. The samples were sectioned vertically into two halves through the centre. One half of each sample the surface and cross-sectional microhardness was measured. The other half was put into demineralization liquid for 14 days, then the surface and cross-sectional microhardness was measured again. The cross section morphology of the samples was observed by scanning electron microscope. RESULTS The surface of enamel had the highest microhardness value, and with the increase of cross- sectional depth, the microhardness value declined gradually. Variance analysis showed that the difference was statistically significant in the cross-section of different depth among the four groups(P<0.05). The microhardness values of the surface and the cross- section at 40 µm of each group in immediate measure showed the values were significantly higher in group A, B and C than in group D. There was no significant difference in the microhardness value of cross-section at 80 µm between group A[(324 ± 17) kg/mm(2)] and group C[(316 ± 20) kg/mm(2)], but they were significantly higher than group D. There was no significant difference between group B[(303 ± 13) kg/mm(2)] and group D[(294 ± 23) kg/mm(2)]. At 120 µm level, the microhardness value of group A was significantly higher than those of the other three groups. After the twice demineralization, the enamel surface microhardness value of the specimens was the same as the first measurement. In the cross-section at 40 µm level, the microhardness value was equal to the value of cross-section at 80 µm level of the first measurement. In the cross- section at 80 µm and 120 µm level, the microhardness value of group A was significantly higher than those of the other three groups. CONCLUSIONS Resin infiltration can effectively strengthen microhardness of enamel surface and cross-section of different depth of artificial caries.
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Affiliation(s)
- Yonghong Liu
- Department of Oral Medicine, The Second Hospital of Hebei Medical University, Shijiazhuang 050000, China
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Akagi R, Kusama S. Comparison Between Neck and Shoulder Stiffness Determined by Shear Wave Ultrasound Elastography and a Muscle Hardness Meter. Ultrasound Med Biol 2015; 41:2266-2271. [PMID: 25944285 DOI: 10.1016/j.ultrasmedbio.2015.04.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/28/2015] [Accepted: 04/01/2015] [Indexed: 06/04/2023]
Abstract
The goals of this study were to compare neck and shoulder stiffness values determined by shear wave ultrasound elastography with those obtained with a muscle hardness meter and to verify the correspondence between objective and subjective stiffness in the neck and shoulder. Twenty-four young men and women participated in the study. Their neck and shoulder stiffness was determined at six sites. Before the start of the measurements, patients rated their present subjective symptoms of neck and shoulder stiffness on a 6-point verbal scale. At all measurement sites, the correlation coefficients between the values of muscle hardness indices determined by the muscle hardness meter and shear wave ultrasound elastography were not significant. Furthermore, individuals' subjective neck and shoulder stiffness did not correspond to their objective symptoms. These results suggest that the use of shear wave ultrasound elastography is essential to more precisely assess neck and shoulder stiffness.
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Affiliation(s)
- Ryota Akagi
- College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama-shi, Saitama, Japan.
| | - Saki Kusama
- College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama-shi, Saitama, Japan
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Kumar S, Liu G, Schloerb DW, Srinivasan MA. Viscoelastic characterization of the primate finger pad in vivo by microstep indentation and three-dimensional finite element models for tactile sensation studies. J Biomech Eng 2015; 137:061002. [PMID: 25751365 DOI: 10.1115/1.4029985] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Indexed: 11/08/2022]
Abstract
When we touch an object, surface loads imposed on the skin are transmitted to thousands of specialized nerve endings (mechanoreceptors) embedded within the skin. These mechanoreceptors transduce the mechanical signals imposed on them into a neural code of the incident stimuli, enabling us to feel the object. To understand the mechanisms of tactile sensation, it is critical to understand the relationship between the applied surface loads, mechanical state at the mechanoreceptor locations, and transduced neural codes. In this paper, we characterize the bulk viscoelastic properties of the primate finger pad and show its relationship to the dynamic firing rate of SA-1 mechanoreceptors. Two three-dimensional (3D) finite element viscoelastic models, a homogeneous and a multilayer model, of the primate fingertip are developed and calibrated with data from a series of force responses to micro-indentation experiments on primate finger pads. We test these models for validation by simulating indentation with a line load and comparing surface deflection with data in the literature (Srinivasan, 1989, "Surface Deflection of Primate Fingertip Under Line Load," J. Biomech., 22(4), pp. 343-349). We show that a multilayer model with an elastic epidermis and viscoelastic core predicts both the spatial and temporal biomechanical response of the primate finger pad. Finally, to show the utility of the model, ramp and hold indentation with a flat plate is simulated. The multilayer model predicts the strain energy density at a mechanoreceptor location would decay at the same rate as the average dynamic firing rate of SA-1 mechanoreceptors in response to flat plate indentation (previously observed by Srinivasan and LaMotte, 1991 "Encoding of Shape in the Responses of Cutaneous Mechanoreceptors," Information Processing in the Somatosensory System (Wenner-Gren International Symposium Series), O. Franzen and J. Westman, eds., Macmillan Press, London, UK), suggesting that the rate of adaptation of SA-1 mechanoreceptors is governed by the viscoelastic nature of its surrounding tissue.
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Li Y, Feng S, Wu W, Li F. Temperature dependent mechanical property of PZT film: an investigation by nanoindentation. PLoS One 2015; 10:e0116478. [PMID: 25768957 PMCID: PMC4358891 DOI: 10.1371/journal.pone.0116478] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 12/09/2014] [Indexed: 11/25/2022] Open
Abstract
Load-depth curves of an unpoled Lead Zirconate Titanate (PZT) film composite as a function of temperature were measured by nanoindentation technique. Its reduce modulus and hardness were calculated by the typical Oliver-Pharr method. Then the true modulus and hardness of the PZT film were assessed by decoupling the influence of substrate using methods proposed by Zhou et al. and Korsunsky et al., respectively. Results show that the indentation depth and modulus increase, but the hardness decreases at elevated temperature. The increasing of indentation depth and the decreasing of hardness are thought to be caused by the decreasing of the critical stress needed to excite dislocation initiation at high temperature. The increasing of true modulus is attributed to the reducing of recoverable indentation depth induced by back-switched domains. The influence of residual stress on the indentation behavior of PZT film composite was also investigated by measuring its load-depth curves with pre-load strains.
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Affiliation(s)
- Yingwei Li
- Department of Engineering mechanics, School of Civil Engineering, Wuhan University, Wuhan, China
- State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, China
| | - Shangming Feng
- Department of Engineering mechanics, School of Civil Engineering, Wuhan University, Wuhan, China
| | - Wenping Wu
- Department of Engineering mechanics, School of Civil Engineering, Wuhan University, Wuhan, China
| | - Faxin Li
- State Key Lab for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing, China
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Demiral M, Abdel-Wahab A, Silberschmidt V. A numerical study on indentation properties of cortical bone tissue: influence of anisotropy. Acta Bioeng Biomech 2015; 17:3-14. [PMID: 26399190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
PURPOSE The purpose of this study is to investigate the effect of anisotropy of cortical bone tissue on measurement of properties such as direction-dependent moduli and hardness. METHODS An advanced three-dimensional finite element model of microindentation was developed. Different modelling schemes were considered to account for anisotropy of elastic or/and plastic regimes. The elastic anisotropic behaviour was modelled employing an elasticity tensor, and Hill's criteria were used to represent the direction-dependent post-yield behaviour. The Oliver-Pharr method was used in the data analysis. RESULTS A decrease in the value of the transverse elasticity modulus resulted in the increased material's indentation modulus measured in the longitudinal direction and a decreased one in the transverse direction, while they were insensitive to the anisotropy in post-elastic regime. On the other hand, an increase in plastic anisotropy led to a decrease in measured hardness for both directions, but by a larger amount in the transverse one. The size effect phenomenon was found to be also sensitive to anisotropy. CONCLUSIONS The undertaken analysis suggests that the Oliver-Pharr method is a useful tool for first-order approximations in the analysis of mechanical properties of anisotropic materials similar to cortical bone, but not necessarily for the materials with low hardening reserves in the plastic regime.
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Affiliation(s)
- Murat Demiral
- Department of Mechanical Engineering, University of Turkish Aeronautical Association, 06790 Ankara, Turkey
| | - Adel Abdel-Wahab
- Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, LE11 3TU, UK
| | - Vadim Silberschmidt
- Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, LE11 3TU, UK
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Maruyama N, Shibata Y, Swain MV, Kataoka Y, Takiguchi Y, Yamada A, Maki K, Miyazaki T. Strain-rate stiffening of cortical bone: observations and implications from nanoindentation experiments. Nanoscale 2014; 6:14863-14871. [PMID: 25363088 DOI: 10.1039/c4nr03180f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
While bone mineralization is considered to be responsible for its stiffness, bone durability partially associated with the time-dependent viscoelasticity of matrix proteins is still poorly elucidated. Here we demonstrate a novel mechanism of highly mineralized bone durability almost independent of inherent viscoelastic behaviour along with a protocol for measuring the mechanical properties of mineralized tissues. Strain-rate nanoindentation tests showed substantial stiffening of the highly mineralized calvarial bone, whereas large creep or stress relaxation was observed during constant load or displacement tests, respectively. Based on the lower viscoelasticity of the highly mineralized structure, such large time-dependent response appears to be associated with nanoscale dimensional recovery, rather than viscoelastic behaviour, implying the inverse namely strain-rate dependent dilatant behaviour. This dilatant expansion increased the indenter penetration resistance into the surface, enhancing instantaneous stiffness. The associated stiffening and higher effective elastic modulus were highly strain-rate dependent and more readily observed in more highly mineralized tissues such as the calvarial bone. Such strain-rate stiffening and consequent dimensional recovery may be vital responses of bone tissues against excessive deformation to maintain tissue integrity.
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Affiliation(s)
- Noriko Maruyama
- Department of Orthodontics, Showa University School of Dentistry, 2-1-1, Kitasenzoku, Ohta-ku, Tokyo 145-8515, Japan
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Mikula E, Hollman K, Chai D, Jester JV, Juhasz T. Measurement of corneal elasticity with an acoustic radiation force elasticity microscope. Ultrasound Med Biol 2014; 40:1671-9. [PMID: 24726798 PMCID: PMC5919192 DOI: 10.1016/j.ultrasmedbio.2013.11.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 11/05/2013] [Accepted: 11/06/2013] [Indexed: 05/12/2023]
Abstract
To investigate the role of collagen structure in corneal biomechanics, measurement of localized corneal elasticity with minimal destruction to the tissue is necessary. We adopted the recently developed acoustic radiation force elastic microscopy (ARFEM) technique to measure localize biomechanical properties of the human cornea. In ARFEM, a low-frequency, high-intensity acoustic force is used to displace a femtosecond laser-generated microbubble, while high-frequency, low-intensity ultrasound is used to monitor the position of the microbubble within the cornea. Two ex vivo human corneas from a single donor were dehydrated to physiologic thickness, embedded in gelatin and then evaluated using the ARFEM technique. In the direction perpendicular to the corneal surface, ARFEM measurements provided elasticity values of E = 1.39 ± 0.28 kPa for the central anterior cornea and E = 0.71 ± 0.21 kPa for the central posterior cornea in pilot studies. The increased value of corneal elasticity in the anterior cornea correlates with the higher density of interweaving lamellae in this region.
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Affiliation(s)
- Eric Mikula
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, USA.
| | - Kyle Hollman
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA; Soundsight Research, Livonia, Michigan, USA
| | - Dongyul Chai
- Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA
| | - James V Jester
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, USA; Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA
| | - Tibor Juhasz
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, USA; Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA
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Argüelles-Salido E, Lozano-Blasco JM, Subira-Rios J, Bernardo-Villar P, Podio-Lora V, Campoy-Martínez P, Vazquez-Albertino R, Medina-Lopez R. The usefulness of densitometry in predicting the composition and fragility of urolithiasis. ARCH ESP UROL 2014; 67:269-275. [PMID: 24840592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
INTRODUCTION The choice of ideal treatment for a given lithiasis is a crucial factor for its success, minimizing the number of interventions and complications. Previous determination of stone composition and its fragility is desirable, to predict its behavior during extracorporeal shock wave lithotripsy and for evaluation of its appropriateness, or to set the indication for other techniques. OBJETIVES To determine the role of densitometry in the prediction of composition and fragility of urinary lithiasis undergoing SWL. METHODS Experimental prospective, blinded, in vitro study using 193 urinary calculi of known composition : monohydrated calcium oxalate, mixed calcium oxalate, uric acid, and calcium carbonate, obtained from spontaneous passage or surgery. Densitometry and SWL were performed on them. We compare the mineral composition of the stone and mineral density of each composition group to check if they are characteristic of each type and correlate these parameters with the energy dose required to fragment them down to a given fragment size. RESULTS Only 53 out of 193 stones showed valuable data. Calcium carbonate was the composition showing grater mineral content and density (1,24 gr and 0,47 gr/cm2), followed by mixed oxalate (0,51/0,26) and uric acid (0,52/ 0,15), finishing with the monohydrate calcium oxalate group (0,32/0,05).Only the comparison between calcium carbonate and monohydrated calcium oxalate showed statistically significant results (p<0,05). Correlation coefficients between mineral content (0,347) and density (0,424) and the energy used for stone fragmentation to a given fragment size were statistically significant (p<0,05) CONCLUSIONS: In our study, the use of densitometry to determine stone composition and lithiasic fragility did not show conclusive results due to the limited number of calculi tested. Nevertheless, there are signs that, with a different study design , more practically useful results could be achieved.
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Affiliation(s)
| | | | - Jorge Subira-Rios
- Servicio de Urologia. Hospital Universitario Virgen del Rocio. Sevilla.Spain
| | | | - Virtudes Podio-Lora
- Unidad de Analisis Clinicos.Hospital Universitario Virgen del Rocio. Sevilla.Spain
| | - Pedro Campoy-Martínez
- Unidad de Urologia y Nefrologia.Hospital Universitario Virgen del Rocio. Sevilla.Spain
| | | | - Rafael Medina-Lopez
- Unidad de Urologia y Nefrologia.Hospital Universitario Virgen del Rocio. Sevilla.Spain
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Rahmani Y, Koopman R, Denisov D, Schall P. Visualizing the strain evolution during the indentation of colloidal glasses. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 89:012304. [PMID: 24580224 DOI: 10.1103/physreve.89.012304] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Indexed: 06/03/2023]
Abstract
We use an analog of nanoindentation on a colloidal glass to elucidate the incipient plastic deformation of glasses. By tracking the motion of the individual particles in three dimensions, we visualize the strain field and glass structure during the emerging deformation. At the onset of flow, we observe a power-law distribution of strain indicating strongly correlated deformation, and reflecting a critical state of the glass. At later stages, the strain acquires a Gaussian distribution, indicating that plastic events become uncorrelated. Investigation of the glass structure using both static and dynamic measures shows a weak correlation between the structure and the emerging strain distribution. These results indicate that the onset of plasticity is governed by strong power-law correlations of strain, weakly biased by the heterogeneous glass structure.
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Affiliation(s)
- Y Rahmani
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
| | - R Koopman
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
| | - D Denisov
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
| | - P Schall
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
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Ghosh S, Craig Dutton J, Han B. Measurement of spatiotemporal intracellular deformation of cells adhered to collagen matrix during freezing of biomaterials. J Biomech Eng 2013; 136:021025. [PMID: 24317364 DOI: 10.1115/1.4026180] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Accepted: 12/09/2013] [Indexed: 01/24/2023]
Abstract
Preservation of structural integrity inside cells and at cell-extracellular matrix (ECM) interfaces is a key challenge during freezing of biomaterials. Since the post-thaw functionality of cells depends on the extent of change in the cytoskeletal structure caused by complex cell-ECM adhesion, spatiotemporal deformation inside the cell was measured using a newly developed microbead-mediated particle tracking deformetry (PTD) technique using fibroblast-seeded dermal equivalents as a model tissue. Fibronectin-coated 500 nm diameter microbeads were internalized in cells, and the microbead-labeled cells were used to prepare engineered tissue with type I collagen matrices. After a 24 h incubation the engineered tissues were directionally frozen, and the cells were imaged during the process. The microbeads were tracked, and spatiotemporal deformation inside the cells was computed from the tracking data using the PTD method. Effects of particle size on the deformation measurement method were tested, and it was found that microbeads represent cell deformation to acceptable accuracy. The results showed complex spatiotemporal deformation patterns in the cells. Large deformation in the cells and detachments of cells from the ECM were observed. At the cellular scale, variable directionality of the deformation was found in contrast to the one-dimensional deformation pattern observed at the tissue scale, as found from earlier studies. In summary, this method can quantify the spatiotemporal deformation in cells and can be correlated to the freezing-induced change in the structure of cytosplasm and of the cell-ECM interface. As a broader application, this method may be used to compute deformation of cells in the ECM environment for physiological processes, namely cell migration, stem cell differentiation, vasculogenesis, and cancer metastasis, which have relevance to quantify mechanotransduction.
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Zdunek A, Kurenda A. Determination of the elastic properties of tomato fruit cells with an atomic force microscope. Sensors (Basel) 2013; 13:12175-91. [PMID: 24030683 PMCID: PMC3821342 DOI: 10.3390/s130912175] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 08/23/2013] [Accepted: 09/05/2013] [Indexed: 01/11/2023]
Abstract
Since the mechanical properties of single cells together with the intercellular adhesive properties determine the macro-mechanical properties of plants, a method for evaluation of the cell elastic properties is needed to help explanation of the behavior of fruits and vegetables in handling and food processing. For this purpose, indentation of tomato mesocarp cells with an atomic force microscope was used. The Young's modulus of a cell using the Hertz and Sneddon models, and stiffness were calculated from force-indentation curves. Use of two probes of distinct radius of curvature (20 nm and 10,000 nm) showed that the measured elastic properties were significantly affected by tip geometry. The Young's modulus was about 100 kPa ± 35 kPa and 20 kPa ± 14 kPa for the sharper tip and a bead tip, respectively. Moreover, large variability regarding elastic properties (>100%) among cells sampled from the same region in the fruit was observed. We showed that AFM provides the possibility of combining nano-mechanical properties with topography imaging, which could be very useful for the study of structure-related properties of fruits and vegetables at the cellular and sub-cellular scale.
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Affiliation(s)
- Artur Zdunek
- Institute of Agrophysics, Polish Academy of Sciences, Doswiadczalna 4, Lublin 20-290, Poland; E-Mail: (A.K.)
| | - Andrzej Kurenda
- Institute of Agrophysics, Polish Academy of Sciences, Doswiadczalna 4, Lublin 20-290, Poland; E-Mail: (A.K.)
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Pani AK, Vadlamudi VK, Mohanta HK. Development and comparison of neural network based soft sensors for online estimation of cement clinker quality. ISA Trans 2013; 52:19-29. [PMID: 22940135 DOI: 10.1016/j.isatra.2012.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 06/08/2012] [Accepted: 07/11/2012] [Indexed: 06/01/2023]
Abstract
The online estimation of process outputs mostly related to quality, as opposed to their belated measurement by means of hardware measuring devices and laboratory analysis, represents the most valuable feature of soft sensors. As of now there have been very few attempts for soft sensing of cement clinker quality which is mostly done by offline laboratory analysis resulting at times in low quality clinker. In the present work three different neural network based soft sensors have been developed for online estimation of cement clinker properties. Different input and output data for a rotary cement kiln were collected from a cement plant producing 10,000 tons of clinker per day. The raw data were pre-processed to remove the outliers and the resulting missing data were imputed. The processed data were then used to develop a back propagation neural network model, a radial basis network model and a regression network model to estimate the clinker quality online. A comparison of the estimation capabilities of the three models has been done by simulation of the developed models. It was observed that radial basis network model produced better estimation capabilities than the back propagation and regression network models.
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Affiliation(s)
- Ajaya Kumar Pani
- Department of Chemical Engineering, Birla Institute of Technology and Science, Pilani 333031, India.
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29
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Toledano M, Cabello I, Yamauti M, Giannini M, Aguilera FS, Osorio E, Osorio R. Resistance to degradation of resin-dentin bonds produced by one-step self-etch adhesives. Microsc Microanal 2012; 18:1480-1493. [PMID: 23217278 DOI: 10.1017/s1431927612013529] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The objective of this article is to evaluate the resistance to degradation of resin-dentin bonds formed with three one-step adhesives. Flat, mid-coronal dentin surfaces were bonded with the self-etching adhesives [Tokuyama Bond Force (TBF), One Up Bond F Plus (OUB), and G-Bond (GB)]. The bonded teeth were subjected to fatigue loading, chemical degradation, and stored in distilled water for four time periods (up to 12 months). Specimens were tested for microtensile bond strength and microleakage. Fractographic analysis was performed by scanning electron microscopy. Bonded interfaces were examined by light microscopy using Masson's trichrome staining. An atomic force microscope was employed to analyze phase separation and surface nanoroughness (Ra) at the polymers. Vickers microhardness and the degree of the conversion (DC) were also determined. ANOVA and multiple comparisons tests were performed. Bond strength significantly decreased after the chemical challenge, but not after load cycling. Aging decreased bond strength after 6 months in TBF and GB, in OUB after 12 months. An increase of the nonresin protected collagen zone occurred in all groups, after storing. TBF showed the highest roughness, microhardness, and DC values, and GB showed the lowest. Mild self-etch one-step adhesives (TBF/OUB) showed a higher degree of cure, lower hydrophilicity, and major resistance to degradation of resin-dentin bonds when compared to highly acidic self-etching adhesive (GB).
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Affiliation(s)
- Manuel Toledano
- University of Granada, Faculty of Dentistry, Dental Materials Section, Colegio Máximo de Cartuja s/n, 18071, Granada, Spain.
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30
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Hemmasizadeh A, Autieri M, Darvish K. Multilayer material properties of aorta determined from nanoindentation tests. J Mech Behav Biomed Mater 2012; 15:199-207. [PMID: 23123343 PMCID: PMC3597096 DOI: 10.1016/j.jmbbm.2012.06.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 06/05/2012] [Accepted: 06/12/2012] [Indexed: 10/28/2022]
Abstract
In a wide range of biomechanical modeling of aorta from traumatic injury to stent grafts, the arterial wall has been considered as a single homogeneous layer vessel, ignoring the fact that arteries are composed of distinct anatomical layers with different mechanical characteristics. In this study, using a custom-made nanoindentation technique, changes in the mechanical properties of porcine thoracic aorta wall in the radial direction were characterized using a quasi-linear viscoelastic model. Two layers of equal thickness were mechanically distinguishable in descending aorta based on the radial variations in the instantaneous Young's modulus E and reduced relaxation function G(t). Overall, comparison of E and G(∞) of the outer half (70.27±2.47 kPa and 0.35±0.01) versus the inner half (60.32±1.65 kPa and 0.33±0.01) revealed that the outer half was stiffer and showed less relaxation. The results were used to explain local mechanisms of deformation, force transmission, tear propagation and failure in arteries.
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Affiliation(s)
- Ali Hemmasizadeh
- Department of Mechanical Engineering, College of Engineering, Temple University, 1947N. 12th Street, Philadelphia, PA 19122, USA
| | - Michael Autieri
- Department of Physiology, School of Medicine, Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
| | - Kurosh Darvish
- Department of Mechanical Engineering, College of Engineering, Temple University, 1947N. 12th Street, Philadelphia, PA 19122, USA
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Abstract
In this study the saliency of hardness and softness were investigated in an active haptic search task. Two experiments were performed to explore these properties in different contexts. In Experiment 1, blindfolded participants had to grasp a bundle of spheres and determine the presence of a hard target among soft distractors or vice versa. If the difference in compliance between target and distractors was small, reaction times increased with the number of items for both features; a serial strategy was found to be used. When the difference in compliance was large, the reaction times were independent of the number of items, indicating a parallel strategy. In Experiment 2, blindfolded participants pressed their hand on a display filled with hard and soft items. In the search for a soft target, increasing reaction times with the number of items were found, but the location of target and distractors appeared to have a large influence on the search difficulty. In the search for a hard target, reaction times did not depend on the number of items. In sum, this showed that both hardness and softness are salient features.
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Chin CJ, Franklin JH, Turner B, Moukarbel RV, Chandarana S, Fung K, Yoo J, Doyle PC. A novel tool for the objective measurement of neck fibrosis: validation in clinical practice. J Otolaryngol Head Neck Surg 2012; 41:320-326. [PMID: 23092834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023] Open
Abstract
BACKGROUND Radiotherapy is commonly used to treat neoplasms of the head and neck, and fibrosis is a known side effect. The Cutometer is a device that quantifies properties of the skin. The goal of the study was to validate the Cutometer in normal neck tissues and then quantify fibrosis in radiated necks. METHODS We performed a prospective study of 251 patients. The elasticity and stiffness parameters were recorded. Control patients were compared to determine the correlation between their left and right sides. Next, the treatment groups were compared using a nonparametric test (Kruskal-Wallis). RESULTS We found a significant correlation between the left and right sides of the control patients' necks, supporting the view that the Cutometer provides reproducible measurements in the normal neck. Furthermore, the Cutometer demonstrated reduced elasticity in necks treated with radiation, surgery-radiation, and chemoradiation. No significant difference in stiffness was seen. CONCLUSION The Cutometer may serve as a valuable and valid tool for the measurement of neck skin elasticity. Radiated patients have a quantifiable decrease in their skin elasticity.
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Affiliation(s)
- Christopher J Chin
- Department of Otolaryngology–Head and Neck Surgery, Western University, London, ON
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33
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Gallego-Gómez F, Morales-Flórez V, Blanco A, de la Rosa-Fox N, López C. Water-dependent micromechanical and rheological properties of silica colloidal crystals studied by nanoindentation. Nano Lett 2012; 12:4920-4924. [PMID: 22871185 DOI: 10.1021/nl3024998] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Here we show the suitability of nanoindentation to study in detail the micromechanical response of silica colloidal crystals (CCs). The sensitivity to displacements smaller than the submicrometer spheres size, even resolving discrete events and superficial features, revealed particulate features with analogies to atomic crystals. Significant robustness, long-range structural deformation, and large energy dissipation were found. Easily implemented temperature/rate-dependent nanoindentation quantified the paramount role of adsorbed water endowing silica CCs with properties of wet granular materials like viscoplasticity. A novel "nongranular" CC was fabricated by substituting capillary bridges with silica necks to directly test water-independent mechanical response. Silica CCs, as specific (nanometric, ordered) wet granular assemblies with well-defined configuration, may be useful model systems for granular science and capillary cohesion at the nanoscale.
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Affiliation(s)
- Francisco Gallego-Gómez
- Instituto de Ciencia de Materiales de Madrid, ICMM (CSIC), C/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain.
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Hayashi-Sakai S, Sakai J, Sakamoto M, Endo H. Determination of fracture toughness of human permanent and primary enamel using an indentation microfracture method. J Mater Sci Mater Med 2012; 23:2047-2054. [PMID: 22639149 DOI: 10.1007/s10856-012-4678-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 05/11/2012] [Indexed: 06/01/2023]
Abstract
The purpose of the present study was to examine the fracture toughness and Vickers microhardness number of permanent and primary human enamel using the indentation microfracture method. Crack resistance and a parameter indirectly related to fracture toughness were measured in 48 enamel specimens from 16 permanent teeth and 12 enamel specimens obtained from six primary teeth. The Vickers microhardness number of the middle portion was greater than the upper portion in primary enamel. The fracture toughness was highest in the middle portion of permanent enamel, because fracture toughness greatly depends upon microstructure. These findings suggest that primary teeth are not miniature permanent teeth but have specific and characteristic mechanical properties.
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Affiliation(s)
- Sachiko Hayashi-Sakai
- Division of Pediatric Dentistry, Department of Oral Health Science, Course for Oral Life Science, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-Dori, Chuo-ku, Niigata, 951-8514, Japan.
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Seifzadeh A, Oguamanam DCD, Trutiak N, Hurtig M, Papini M. Determination of nonlinear fibre-reinforced biphasic poroviscoelastic constitutive parameters of articular cartilage using stress relaxation indentation testing and an optimizing finite element analysis. Comput Methods Programs Biomed 2012; 107:315-326. [PMID: 21802762 DOI: 10.1016/j.cmpb.2011.07.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 05/26/2011] [Accepted: 07/06/2011] [Indexed: 05/31/2023]
Abstract
An inverse method was developed to determine the material constitutive parameters of human articular cartilage from stress relaxation indentation tests. The cartilage was modeled as a fibre-reinforced nonlinear biphasic poroviscoelastic material, and a finite element (FE) model was used with a simulated annealing (SA) optimization algorithm to determine the material parameters that minimized the error between the experimental and predicted time dependant indentation loads. The values of the 15 optimized material parameters were found to be insensitive to the initial guesses, and, when friction between the indenter and the cartilage was considered, resulted in good agreement between the measured stress relaxation response and the FE prediction (R(2)=0.99). The optimized material parameters determined from experiments that used two different indenter sizes on the same samples were compared. When assuming frictionless contact between the indenter and the cartilage, all of the optimized parameters except for the Poisson's ratio were found to be relatively insensitive to indenter size. A second set of models that included frictional contact greatly reduced the sensitivity of the optimized Poisson's ratio to indenter size, thus confirming the validity of the model and demonstrating the importance of modeling friction. The results also demonstrate the robustness of the SA optimization algorithm to ensure convergence of a large number of material properties to a global minimum regardless of the quality of the initial guesses.
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Affiliation(s)
- A Seifzadeh
- Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, Ontario, Canada
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36
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Bechtle S, Özcoban H, Lilleodden ET, Huber N, Schreyer A, Swain MV, Schneider GA. Hierarchical flexural strength of enamel: transition from brittle to damage-tolerant behaviour. J R Soc Interface 2012; 9:1265-74. [PMID: 22031729 PMCID: PMC3350718 DOI: 10.1098/rsif.2011.0498] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 10/03/2011] [Indexed: 11/12/2022] Open
Abstract
Hard, biological materials are generally hierarchically structured from the nano- to the macro-scale in a somewhat self-similar manner consisting of mineral units surrounded by a soft protein shell. Considerable efforts are underway to mimic such materials because of their structurally optimized mechanical functionality of being hard and stiff as well as damage-tolerant. However, it is unclear how different hierarchical levels interact to achieve this performance. In this study, we consider dental enamel as a representative, biological hierarchical structure and determine its flexural strength and elastic modulus at three levels of hierarchy using focused ion beam (FIB) prepared cantilevers of micrometre size. The results are compared and analysed using a theoretical model proposed by Jäger and Fratzl and developed by Gao and co-workers. Both properties decrease with increasing hierarchical dimension along with a switch in mechanical behaviour from linear-elastic to elastic-inelastic. We found Gao's model matched the results very well.
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Affiliation(s)
- Sabine Bechtle
- Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany
| | - Hüseyin Özcoban
- Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany
| | - Erica T. Lilleodden
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany
| | - Norbert Huber
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany
| | - Andreas Schreyer
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany
| | | | - Gerold A. Schneider
- Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany
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37
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Abstract
In this work, a new procedure is demonstrated to retrieve the conservative and dissipative contributions to contact resonance atomic force microscopy (CR-AFM) measurements from the contact resonance frequency and resonance amplitude. By simultaneously tracking the CR-AFM frequency and amplitude during contact AFM scanning, the contact stiffness and damping were mapped with nanoscale resolution on copper (Cu) interconnects and low-k dielectric materials. A detailed surface mechanical characterization of the two materials and their interfaces was performed in terms of elastic moduli and contact damping coefficients by considering the system dynamics and included contact mechanics. Using Cu as a reference material, the CR-AFM measurements on the patterned structures showed a significant increase in the elastic modulus of the low-k dielectric material compared with that of a blanket pristine film. Such an increase in the elastic modulus suggests an enhancement in the densification of low-k dielectric films during patterning. In addition, the subsurface response of the materials was investigated in load-dependent CR-AFM point measurements and in this way a depth dimension was added to the common CR-AFM surface characterization. With the new proposed measurement procedure and analysis, the present investigation provides new insights into characterization of surface and subsurface mechanical responses of nanoscale structures and the integrity of their interfaces.
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Affiliation(s)
- Gheorghe Stan
- Nanomechanical Properties Group, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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38
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Pathak S, Vachhani SJ, Jepsen KJ, Goldman HM, Kalidindi SR. Assessment of lamellar level properties in mouse bone utilizing a novel spherical nanoindentation data analysis method. J Mech Behav Biomed Mater 2012; 13:102-17. [PMID: 22842281 DOI: 10.1016/j.jmbbm.2012.03.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 03/23/2012] [Accepted: 03/26/2012] [Indexed: 11/18/2022]
Abstract
In this work, we demonstrate the viability of using our recently developed data analysis procedures for spherical nanoindentation in conjunction with Raman spectroscopy for studying lamellar-level correlations between the local composition and local mechanical properties in mouse bone. Our methodologies allow us to convert the raw load-displacement datasets to much more meaningful indentation stress-strain curves that accurately capture the loading and unloading elastic moduli, the indentation yield points, as well as the post-yield characteristics in the tested samples. Using samples of two different inbred mouse strains, A/J and C57BL/6J (B6), we successfully demonstrate the correlations between the mechanical information obtained from spherical nanoindentation measurements to the local composition measured using Raman spectroscopy. In particular, we observe that a higher mineral-to-matrix ratio correlated well with a higher local modulus and yield strength in all samples. Thus, new bone regions exhibited lower moduli and yield strengths compared to more mature bone. The B6 mice were also found to exhibit lower modulus and yield strength values compared to the more mineralized A/J strain.
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Affiliation(s)
- Siddhartha Pathak
- Department of Materials Science and Engineering, Drexel University, Philadelphia, PA 19104, USA.
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39
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Clifford CA, Seah MP. Modelling of surface nanoparticle inclusions for nanomechanical measurements by an AFM or nanoindenter: spatial issues. Nanotechnology 2012; 23:165704. [PMID: 22469815 DOI: 10.1088/0957-4484/23/16/165704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Finite element analysis (FEA) is used to model nanoindentation by a rigid, spherically shaped indenter, axially indenting an elastic two phase polymer system comprised of a cylindrical nanoparticle of compliant polymer set in a semi-infinite matrix of stiffer polymer. The cylindrical nanoparticle is normal to the sample surface. An axisymmetric finite element model is used to determine the reduced modulus measured as a function of the indentation depth for various nanoparticle radii and extensions below the surface. We show how the previous simple analytical equations may be extended to describe these situations with accuracy. This gives excellent agreement with the FEA and provides a clear guide to the maximum indentation depth as a function of both the nanoparticle radius and its thickness consistent with a choice of either computation from the analytical equations or direct measurement with a maximum of 10% error in the measured reduced modulus.
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Affiliation(s)
- Charles A Clifford
- Analytical Science Division, National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK.
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40
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Sweers KKM, van der Werf KO, Bennink ML, Subramaniam V. Spatially resolved frequency-dependent elasticity measured with pulsed force microscopy and nanoindentation. Nanoscale 2012; 4:2072-2077. [PMID: 22331128 DOI: 10.1039/c2nr12066f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Recently several atomic force microscopy (AFM)-based surface property mapping techniques like pulsed force microscopy (PFM), harmonic force microscopy or Peakforce QNM® have been introduced to measure the nano- and micro-mechanical properties of materials. These modes all work at different operating frequencies. However, complex materials are known to display viscoelastic behavior, a combination of solid and fluid-like responses, depending on the frequency at which the sample is probed. In this report, we show that the frequency-dependent mechanical behavior of complex materials, such as polymer blends that are frequently used as calibration samples, is clearly measurable with AFM. Although this frequency-dependent mechanical behavior is an established observation, we demonstrate that the new high frequency mapping techniques enable AFM-based rheology with nanoscale spatial resolution over a much broader frequency range compared to previous AFM-based studies. We further highlight that it is essential to account for the frequency-dependent variation in mechanical properties when using these thin polymer samples as calibration materials for elasticity measurements by high-frequency surface property mapping techniques. These results have significant implications for the accurate interpretation of the nanomechanical properties of polymers or complex biological samples. The calibration sample is composed of a blend of soft and hard polymers, consisting of low-density polyethylene (LDPE) islands in a polystyrene (PS) surrounding, with a stiffness of 0.2 GPa and 2 GPa respectively. The spring constant of the AFM cantilever was selected to match the stiffness of LDPE. From 260 Hz to 1100 Hz the sample was imaged with the PFM method. At low frequencies (0.5-35 Hz), single-point nanoindentation was performed. In addition to the material's stiffness, the relative heights of the LDPE islands (with respect to the PS) were determined as a function of the frequency. At the lower operation frequencies for PFM, the islands exhibited lower heights than when measured with tapping mode at 120 kHz. Both spring constants and heights at the different frequencies clearly show a frequency-dependent behavior.
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Affiliation(s)
- Kim K M Sweers
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Enschede, The Netherlands
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41
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Yoon T, Shin WC, Kim TY, Mun JH, Kim TS, Cho BJ. Direct measurement of adhesion energy of monolayer graphene as-grown on copper and its application to renewable transfer process. Nano Lett 2012; 12:1448-52. [PMID: 22335825 DOI: 10.1021/nl204123h] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Direct measurement of the adhesion energy of monolayer graphene as-grown on metal substrates is important to better understand its bonding mechanism and control the mechanical release of the graphene from the substrates, but it has not been reported yet. We report the adhesion energy of large-area monolayer graphene synthesized on copper measured by double cantilever beam fracture mechanics testing. The adhesion energy of 0.72 ± 0.07 J m(-2) was found. Knowing the directly measured value, we further demonstrate the etching-free renewable transfer process of monolayer graphene that utilizes the repetition of the mechanical delamination followed by the regrowth of monolayer graphene on a copper substrate.
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Affiliation(s)
- Taeshik Yoon
- Department of Mechanical Engineering, KAIST, Daejeon 305-701, Korea
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42
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Mares C, Barrientos B, Blanco A. Measurement of transient deformation by color encoding. Opt Express 2011; 19:25712-25722. [PMID: 22273963 DOI: 10.1364/oe.19.025712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a method based on color encoding for measurement of transient 3D deformation in diffuse objects. The object is illuminated by structured light that consists of a fringe pattern with cyan fringes embedded in a white background. Color images are registered and information on each color channel is then separated. Surface features appear on the blue channel while fringes on the red channel. The in-plane components of displacement are calculated via digital correlation of the texture images. Likewise, the resulting fringes serve for the measuring of the out-of-plane component. As crossing of information between signals is avoided, the accuracy of the method is high. This is confirmed by a series of displacement measurements of an aluminum plate.
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Affiliation(s)
- C Mares
- Centro de Investigaciones en Óptica A. C., Loma del Bosque 115, León, Gto. Mexico
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43
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McKee CT, Last JA, Russell P, Murphy CJ. Indentation versus tensile measurements of Young's modulus for soft biological tissues. Tissue Eng Part B Rev 2011; 17:155-64. [PMID: 21303220 PMCID: PMC3099446 DOI: 10.1089/ten.teb.2010.0520] [Citation(s) in RCA: 385] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 02/07/2011] [Indexed: 12/21/2022]
Abstract
In this review, we compare the reported values of Young's modulus (YM) obtained from indentation and tensile deformations of soft biological tissues. When the method of deformation is ignored, YM values for any given tissue typically span several orders of magnitude. If the method of deformation is considered, then a consistent and less ambiguous result emerges. On average, YM values for soft tissues are consistently lower when obtained by indentation deformations. We discuss the implications and potential impact of this finding.
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Affiliation(s)
- Clayton T. McKee
- Department of Surgical and Radiological Science, School of Veterinary Medicine, University of California Davis, Davis, California
| | - Julie A. Last
- Department of Chemical and Biological Engineering, University of Wisconsin–Madison, Madison, Wisconsin
| | - Paul Russell
- Department of Surgical and Radiological Science, School of Veterinary Medicine, University of California Davis, Davis, California
| | - Christopher J. Murphy
- Department of Surgical and Radiological Science, School of Veterinary Medicine, University of California Davis, Davis, California
- Department of Ophthalmology and Vision Science, School of Medicine, University of California Davis, Davis, California
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44
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Hoshi T, Tsukune M, Kobayashi Y, Miyashita T, Fujie MG. Development and evaluation of an identification method for the biomechanical parameters using robotic force measurements, medical images, and FEA. Annu Int Conf IEEE Eng Med Biol Soc 2011; 2011:5386-5391. [PMID: 22255555 DOI: 10.1109/iembs.2011.6091332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This paper presents a new identification method for the biomechanical parameters of human tissues for the purpose of improving the accuracy of dynamic organ simulation. We describe the formulation of the method, and also design a robotic system to implement the method using a robotic probe, a medical imaging device, and a numerical simulator for the finite element analysis (FEA). We carried out an experiment using an experimental system and a tissue phantom to verify the effectiveness of the method. The results of this experiment show that the Young's modulus of the tissue phantom can be estimated with the experimental system. We also compared the estimated values of the Young's moduli with the measured values from a rheometer. These results confirm that the identification method and the system design, proposed and developed in this work, are effective for accurately simulating organ behavior.
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Affiliation(s)
- Takeharu Hoshi
- Faculty of Science and Engineering, Waseda University, Shinjuku-ku, 3-4-1 Okubo, Tokyo, Japan.
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45
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Stifter D, Leiss-Holzinger E, Major Z, Baumann B, Pircher M, Götzinger E, Hitzenberger CK, Heise B. Dynamic optical studies in materials testing with spectral-domain polarization-sensitive optical coherence tomography. Opt Express 2010; 18:25712-25. [PMID: 21164917 DOI: 10.1364/oe.18.025712] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
By combining dynamic mechanical testing with spectral-domain polarization-sensitive optical coherence tomography (SD-PS-OCT) performed at 1550 nm we are able to directly investigate for the first time changes within scattering technical materials during tensile and fracture tests. Spatially and temporally varying polarization patterns, due to defects and material inhomogeneities, were observed within bulk polymer samples and used to finally obtain--with the help of advanced image processing algorithms--quantitative maps of the evolving internal stress distribution. Furthermore, locally increased stress within fiber-reinforced composite materials was identified in situ with SD-PS-OCT to cause depolarizing sites of fiber-matrix debonding prior the onset of complete structural failure.
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Affiliation(s)
- David Stifter
- Christian Doppler Laboratory for Microscopic and Spectroscopic Material Characterization, Center for Surface- and Nanoanalytics, Johannes Kepler University Linz, Altenbergerstrasse 69, 4040 Linz, Austria.
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Blandino M, Mancini MC, Peila A, Rolle L, Vanara F, Reyneri A. Determination of maize kernel hardness: comparison of different laboratory tests to predict dry-milling performance. J Sci Food Agric 2010; 90:1870-1878. [PMID: 20602514 DOI: 10.1002/jsfa.4027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
BACKGROUND Numerous foods are produced from maize, and grain hardness has been described to have an impact on grain end-use value, and in particular for dry-milling performance. RESULTS Thirty-three samples of commercial hybrids have been analysed for test weight (TW), thousand-kernel weight (TKW), hard:soft endosperm ratio (H/S), milling time (MT) and total milling energy (TME) through the Stenvert hardness test, coarse:fine material ratio (C/F), break force (HF) and break energy (HWF) through the puncture test, floating test (FLT), kernel dimensions and sphericity (S), protein (PC), starch (SC), lipid (LC), ash (AC) content and amylose:amylopectin ratio (AS/AP).Total grit yield (TGY) has been obtained through a micromilling procedure and used to compare the efficiency of the tests to predict the dry-milling performance. TW, H/S, MT, TME, C/F, FLT, S, PC, SC and AS/AP were significantly correlated with each other. TW has been confirmed to be a simple estimator of grain hardness. Among the hardness tests, C/F was shown to be the best descriptor of maize milling ability, followed by FLT. A good correlation with TGY has also been observed with H/S, MT, TME and PC, while SC, S and AS/AP seem to play a minor role. The puncture test (HF and HWF) did not offer good indications on the impact of hardness on kernel grinding properties. CONCLUSION This study can be considered as a contribution towards determining kernel properties which influence maize hardness measurement in relation to the end-use processing performance.
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Affiliation(s)
- Massimo Blandino
- Department of Agriculture, Forestry and Land Management, University of Turin, 10095 Grugliasco (TO), Italy.
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Abstract
Although the market for replacement of diseased metacarpophalangeal (MCP) joints is dominated by single-piece silicone prostheses, several two-piece designs have been implanted. One such is the Digital Joint Operative Arthroplasty (DJOA) which consists of a part-spherical stainless steel metacarpal component which articulates within a matching concave phalangeal component made of ultra high molecular weight polyethylene (UHMWPE). A DJOA MCP prosthesis was tested using a clinically-validated finger simulator while a second DJOA prosthesis acted as a statically-loaded soak-control. Testing ran to 7.1 million cycles of flexion-extension. It was found that the UHMWPE components, both test and control, gained in weight by a similar amount. Therefore apparently there was no wear of the test components. However, the initial and final surface finish values of the test stainless steel metacarpal head were relatively high. Calculations based on this roughness data, plus recent dynamically-loaded soak data, may explain the apparent lack of wear.
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Affiliation(s)
- Thomas J Joyce
- School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne, UK.
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Khayyeri H, Checa S, Tägil M, O'Brien FJ, Prendergast PJ. Tissue differentiation in an in vivo bioreactor: in silico investigations of scaffold stiffness. J Mater Sci Mater Med 2010; 21:2331-2336. [PMID: 20037774 DOI: 10.1007/s10856-009-3973-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 12/09/2009] [Indexed: 05/28/2023]
Abstract
Scaffold design remains a main challenge in tissue engineering due to the large number of requirements that need to be met in order to create functional tissues in vivo. Computer simulations of tissue differentiation within scaffolds could serve as a powerful tool in elucidating the design requirements for scaffolds in tissue engineering. In this study, a lattice-based model of a 3D porous scaffold construct derived from micro CT and a mechano-biological simulation of a bone chamber experiment were combined to investigate the effect of scaffold stiffness on tissue differentiation inside the chamber. The results indicate that higher scaffold stiffness, holding pore structure constant, enhances bone formation. This study demonstrates that a lattice approach is very suitable for modelling scaffolds in mechano-biological simulations, since it can accurately represent the micro-porous geometries of scaffolds in a 3D environment and reduce computational costs at the same time.
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Affiliation(s)
- Hanifeh Khayyeri
- Trinity Centre for Bioengineering, School of Engineering, Trinity College, Dublin, Ireland
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Gigler AM, Huber AJ, Bauer M, Ziegler A, Hillenbrand R, Stark RW. Nanoscale residual stress-field mappingaround nanoindents in SiCby IR s-SNOM and confocal Raman microscopy. Opt Express 2009; 17:22351-22357. [PMID: 20052158 DOI: 10.1364/oe.17.022351] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We map a nanoindent in a silicon carbide (SiC) crystal by infrared (IR) scattering-type scanning near-field optical microscopy (s-SNOM) and confocal Raman microscopy and interpret the resulting images in terms of local residual stress-fields. By comparing near-field IR and confocal Raman images, we find that the stress-induced shifts of the longitudinal optical phonon-frequencies (LO) and the related shift of the phonon-polariton near-field resonance give rise to Raman and s-SNOM image contrasts, respectively. We apply single-frequency IR s-SNOM for nanoscale resolved imaging of local stress-fields and confocal Raman microscopy to obtain the complete spectral information about stress-induced shifts of the phonon frequencies at diffraction limited spatial resolution. The spatial extension of the local stress-field around the nanoindent agrees well between both techniques. Our results demonstrate that both methods ideally complement each other, allowing for the detailed analysis of stress-fields at e.g. material and grain boundaries, in Micro-Electro-Mechanical-Systems (MEMS), or in engineered nanostructures.
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Affiliation(s)
- Alexander M Gigler
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich, Germany.
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Ekpenyong AE, Posey CL, Chaput JL, Burkart AK, Marquardt MM, Smith TJ, Nichols MG. Determination of cell elasticity through hybrid ray optics and continuum mechanics modeling of cell deformation in the optical stretcher. Appl Opt 2009; 48:6344-54. [PMID: 19904335 PMCID: PMC3060047 DOI: 10.1364/ao.48.006344] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The optical stretcher is a dual-beam trap capable of stretching individual cells. Previous studies have used either ray- or wave-optical models to compute the optical pressure on the surface of a spherical cell. We have extended the ray-optics model to account for focusing by the spherical interface and the effects of multiple internal reflections. Simulation results for red-blood cells (RBCs) show that internal reflections can lead to significant perturbation of the deformation, leading to a systematic error in the determination of cellular elasticity. Calibration studies show excellent agreement between the predicted and measured escape force, and RBC stiffness measurements are consistent with literature values. Measurements of the elasticity of murine osteogenic cells reveal that these cells are approximately 5.4 times stiffer than RBCs.
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