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Ebrahimi F, Xu H, Fuenmayor E, Major I. Tailoring drug release in bilayer tablets through droplet deposition modeling and injection molding. Int J Pharm 2024; 653:123859. [PMID: 38307401 DOI: 10.1016/j.ijpharm.2024.123859] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/24/2024] [Accepted: 01/25/2024] [Indexed: 02/04/2024]
Abstract
This study explores the innovative production of personalized bilayer tablets, integrating two advanced manufacturing techniques: Droplet Deposition Modeling (DDM) and Injection Molding (IM). Unlike traditional methods limited to customizing dense bilayer medicines, our approach uses Additive Manufacturing (AM) to effectively adjust drug release profiles. Focusing on Caffeine and Paracetamol, we found successful processing for both DDM and IM using Caffeine formulation. The high viscosity of Paracetamol formulation posed challenges during DDM processing. Integrating Paracetamol formulation for the over-molding process proved effective, demonstrating IM's versatility in handling complex formulations. Varying infill percentages in DDM tablets led to distinct porosities affecting diverse drug release profiles in DDM-fabricated tablets. In contrast, tablets with high-density structures formed through the over-molding process displayed slower and more uniform release patterns. Combining DDM and IM techniques allows for overcoming the inherent limitations of each technique independently, enabling the production of bilayer tablets with customizable drug release profiles. The study's results offer promising insights into the future of personalized medicine, suggesting new pathways for the development of customized oral dosage forms.
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Affiliation(s)
- Farnoosh Ebrahimi
- PRISM Research Institute, Technological University of the Shannon, N37 HD68 Athlone, Ireland
| | - Han Xu
- PRISM Research Institute, Technological University of the Shannon, N37 HD68 Athlone, Ireland
| | - Evert Fuenmayor
- PRISM Research Institute, Technological University of the Shannon, N37 HD68 Athlone, Ireland
| | - Ian Major
- PRISM Research Institute, Technological University of the Shannon, N37 HD68 Athlone, Ireland.
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Ebrahimi F, Xu H, Fuenmayor E, Major I. A comparison of droplet deposition modelling, fused filament fabrication, and injection moulding for the production of oral dosage forms containing hydrochlorothiazide. Int J Pharm 2023; 645:123400. [PMID: 37696342 DOI: 10.1016/j.ijpharm.2023.123400] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 09/05/2023] [Accepted: 09/08/2023] [Indexed: 09/13/2023]
Abstract
Additive manufacturing (AM) possesses a transformative potential to revolutionize personalized medicine fabrication. Fused filament fabrication (FFF), an advanced AM technique, enables the development of tailored medicines with customizable dosages and controlled release properties. Nevertheless, filament prerequisites impose material limitations and present considerable challenges, necessitating a comprehensive evaluation of mechanical, rheological, and thermal characteristics to circumvent complications during the FFF process. Droplet deposition modeling (DDM), an innovative AM approach derived from injection molding (IM) technology, processes granulate feedstock to facilitate the production of personalized medicines. This study delves into the effects of FFF, DDM, and IM techniques on the release profiles of Hydrochlorothiazide, a widely employed drug for hypertension and edema treatment. By varying infill density, the investigation assesses the manufactured tablets using DDM and FFF methods. Our findings show that tablets made with FFF and DDM with identical infill densities had distinct microstructures, resulting in variable drug release profiles. Decreasing the infill densities resulted in higher sample porosity, leading to an accelerated drug release rate. A comparative analysis of drug release profiles from DDM and IM fabricated tablets demonstrated notable differences, despite DDM's origins in injection molding technology. This comprehensive study underscores the significance of not only infill densities but also the choice of manufacturing technique, as both factors can profoundly influence drug release profiles. By shedding light on these considerations, the research contributes to the ongoing advancement of personalized medicine through additive manufacturing technologies.
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Affiliation(s)
- Farnoosh Ebrahimi
- PRISM Research Institute, Technological University of the Shannon, N37 HD68 Athlone, Ireland
| | - Han Xu
- PRISM Research Institute, Technological University of the Shannon, N37 HD68 Athlone, Ireland
| | - Evert Fuenmayor
- PRISM Research Institute, Technological University of the Shannon, N37 HD68 Athlone, Ireland
| | - Ian Major
- PRISM Research Institute, Technological University of the Shannon, N37 HD68 Athlone, Ireland.
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Ramezani Dana H, Ebrahimi F. Synthesis, properties, and applications of polylactic
acid‐based
polymers. POLYM ENG SCI 2022. [DOI: 10.1002/pen.26193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Hossein Ramezani Dana
- Mechanics, Surfaces and Materials Processing (MSMP) – EA 7350 Arts et Metiers Institute of Technology Aix‐en‐Provence France
- Texas A&M Engineering Experiment Station (TEES) Texas A&M University College Station Texas USA
| | - Farnoosh Ebrahimi
- PRISM Polymer, Recycling, Industrial, Sustainability and Manufacturing Technological University of the Shannon (TUS) Athlone Ireland
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Affiliation(s)
- Farnoosh Ebrahimi
- Materials Research Institute, Athlone Institute of Technology, Athlone, Ireland
| | - Hossein Ramezani Dana
- Laboratoire de Mécanique, Surface, Matériaux Procédés (MSMP) – EA 7350, Arts et Metiers Institute of Technology, HESAM Université, Aix-en-Provence, France
- Texas A&M Engineering Experiment Station (TEES), Texas A&M University, College Station, TX, USA
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5
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Ebrahimi F. Determining the influence of game treatment on decreasing divorce children's’ stress. Eur Psychiatry 2017. [DOI: 10.1016/j.eurpsy.2017.01.429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
IntroductionOne of the main challenges facing the fact that every society has always called divorce. Phenomenon in modern societies is growing at a rapid rate and adverse effects of economic, social and especially psychological, parents and children.AimThis study pays to determining the influence of game treatment on decreasing divorce children's’ stress.MethodsThe method of study is of testing in which statistical society of study includes all children (girl and boy) of divorced parents. From all statistical society, we have selected a sample about 26 persons by randomly sampling. The instrument for gathering information in this study includes children stress test (SCARED) in which has been studied sample after measuring its narration and stability.ResultThe result of dependent t-test and covariance analysis showed game treatment has meaningful and positive influence on children stress.ConclusionsThe amount of its interference on decreasing divorce children stress is about 83%. It means 83% of the whole remained scores variance is related to game treatment interference.Disclosure of interestThe author has not supplied his declaration of competing interest.
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Ebrahimi F, Farazi R, Karimi E, Beygi H. Dichlorodimethylsilane mediated one-step synthesis of hydrophilic and hydrophobic silica nanoparticles. ADV POWDER TECHNOL 2017. [DOI: 10.1016/j.apt.2016.12.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Moustakis C, Ernst I, Kittel C, Eich H, Krieger T, Duma M, Oechsner M, Ganswindt U, Heinz C, Alheit H, Blank H, Nestle U, Wiehle R, Kornhuber C, Ostheimer C, Petersen C, Albers D, Pollul G, Baus W, Altenstein G, Blanck O, Beckers E, Sterzing F, Kretschmer M, Seegenschmiedt H, Maass T, Droege S, Wolf U, Schoeffler J, Thiele M, Ciernik I, Ebrahimi F, Guckenberger M. Results of the Planning Comparison Study SBRT of NSCLC. Int J Radiat Oncol Biol Phys 2015. [DOI: 10.1016/j.ijrobp.2015.07.2012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Grajewski L, Kneifel C, Ciernik I, Ebrahimi F, Krause L. Clinical Experience with the Ruthenium- plaque Brachytherapy in Case of Choroidal Melanoma. Acta Ophthalmol 2015. [DOI: 10.1111/j.1755-3768.2015.0615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- L. Grajewski
- Department of Ophthalmology; Städtisches Klinikum Dessau; Dessau Germany
| | - C. Kneifel
- Department of Ophthalmology; Städtisches Klinikum Dessau; Dessau Germany
| | - I. Ciernik
- Department of Radiotherapy and Radiation Oncology; Städtisches Klinikum Dessau; Dessau Germany
| | - F. Ebrahimi
- Department of Radiotherapy and Radiation Oncology; Städtisches Klinikum Dessau; Dessau Germany
| | - L. Krause
- Department of Ophthalmology; Städtisches Klinikum Dessau; Dessau Germany
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Ebrahimi F, Gopalan V, Wahab R, Smith R, Lam A. 148 MIR-126 expression and redugaltion in colorectal cancer biology and its impact on clinicopathological features. Eur J Cancer 2015. [DOI: 10.1016/s0959-8049(16)30046-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Ebrahimi F, Raman R. Plasmoids Formation During Simulations of Coaxial Helicity Injection in the National Spherical Torus Experiment. Phys Rev Lett 2015; 114:205003. [PMID: 26047235 DOI: 10.1103/physrevlett.114.205003] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Indexed: 06/04/2023]
Abstract
The formation of an elongated Sweet-Parker current sheet and a transition to plasmoid instability has for the first time been predicted by simulations in a large-scale toroidal fusion plasma in the absence of any preexisting instability. Plasmoid instability is demonstrated through resistive MHD simulations of transient coaxial helicity injection experiments in the National Spherical Torus Experiment (NSTX). Consistent with the theory, fundamental characteristics of the plasmoid instability, including fast reconnection rate, have been observed in these realistic simulations. Motivated by the simulations, experimental camera images have been revisited and suggest the existence of reconnecting plasmoids in NSTX. Global, system-size plasmoid formation observed here should also have strong implications for astrophysical reconnection, such as rapid eruptive solar events.
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Affiliation(s)
- F Ebrahimi
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08543, USA
| | - R Raman
- University of Washington, Seattle, Washington 98195, USA
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Kamalinasab Z, Mahdavi A, Ebrahimi M, Vahidi Nekoo M, Aghaei M, Ebrahimi F. Effect of teaching stress management skills on self-esteem and behavioral adjustment in people with somatomotor disabilities. J Med Life 2015; 8:163-168. [PMID: 28316725 PMCID: PMC5319265] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Objective: Psychological interventions for enhancing mental health in those with somatomotor-physical disabilities are vital. The existing research aimed to examine the effect of teaching stress management skills on self-esteem and behavioral adjustment in individuals with somatomotor-physical disabilities. Methodology: The method of the survey was semi-experimental with a pre-test post-test design and a control group. Hence, in Tehran, 40 girls with somatomotor-physical disabilities were selected by using convenience sampling, and they were divided into two groups: control and experiment. Both groups were tested by using a demography questionnaire, Rozenberg's self-esteem scale, and a behavioral adjustment questionnaire. Afterwards, the test group received lessons on stress management within ten sessions, but the control group received no interventions. Then both groups were post-tested, and the collected data were analyzed by using descriptive and inferential statistics methods through SPSS software. Findings: Findings showed that teaching stress management skills significantly increased self-esteem and behavioral adjustment in girls with somatomotor-physical disabilities (p < 0.001). Conclusion: According to the study, it could be concluded that teaching stress management skills is an effective way to help endangered individuals such as girls who have somatomotor-physical disabilities because it is highly efficient especially when it is performed in groups, it is cheap, and acceptable by different people.
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Affiliation(s)
- Z Kamalinasab
- General Psychology, Islamic Azad University, Science and Research Branch, Tehran, Iran
| | - A Mahdavi
- Department of Psychology, Faculty of Psychology and Educational Sciences, University of Payam Noor, Tehran, Iran
| | - M Ebrahimi
- Clinical Psychology, Islamic Azad University, Science and Research Branch, Tehran, Iran
| | - M Vahidi Nekoo
- Clinical Psychology, Islamic Azad University, Science and Research Branch, Tehran, Iran
| | - M Aghaei
- Department of Psychology, Faculty of Psychology and Educational Sciences, University of Tehran, Tehran, Iran
| | - F Ebrahimi
- General Psychology, Islamic Azad University, Science and Research Branch, Tehran, Iran
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Masoud M, Ebrahimi F, Minai-Tehrani D. Effect of cimetidine on catalase activity of Pseudomonas aeruginosa: a suggested mechanism of action. J Mol Microbiol Biotechnol 2014; 24:196-201. [PMID: 24993120 DOI: 10.1159/000364872] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Catalase is an important enzyme for the degradation of hydrogen peroxide in cells. Bacteria have potent catalase to deal with H2O2 in their medium culture. Any chemicals that inhibit catalase activity can be harmful for cells. Histamine H2 antagonist drugs such as cimetidine and ranitidine are used for the treatment of gastrointestinal tract disorders. The present results showed that cimetidine could inhibit the catalase activity of Pseudomonas aeruginosa in a competitive inhibition. The determination of IC50 value and Ki (6.5 μM) of cimetidine demonstrated that the enzyme binds to the drug with high affinity. Binding of the drug to the enzyme was pH-dependent and no binding was observed at basic pH (>9) and acidic pH (<6). Moreover, the imidazole ring and cyanoguanidine group of cimetidine may play an important role in inhibition by binding to Fe in heme group and glutamic acid 51 residue on the enzyme, respectively. Ranitidine had no effect on the catalase activity.
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Affiliation(s)
- Masoudeh Masoud
- BioResearch Lab, Faculty of Biological Sciences, Shahid Beheshti University, GC, Tehran, Iran
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Abstract
The constraint imposed by magnetic helicity conservation on the α effect is considered for both magnetically and flow dominated self-organizing plasmas. Direct numerical simulations are presented for a dominant contribution to the α effect, which can be cast in the functional form of a total divergence of an averaged helicity flux, called the helicity-flux-driven α (Hα) effect. Direct numerical simulations of the Hα effect are presented for two examples-the magnetically dominated toroidal plasma unstable to tearing modes, and the flow-dominated accretion disk.
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Affiliation(s)
- F Ebrahimi
- Center for Magnetic Self-Organization, Princeton Center for Heliospheric Physics, and Max-Planck/Princeton Center for Plasma Physics, Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
| | - A Bhattacharjee
- Center for Magnetic Self-Organization, Princeton Center for Heliospheric Physics, and Max-Planck/Princeton Center for Plasma Physics, Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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Ebrahimi F, Kolehmainen E, Laari A, Haario H, Semenov D, Turunen I. Determination of kinetics of percarboxylic acids synthesis in a microreactor by mathematical modeling. Chem Eng Sci 2012. [DOI: 10.1016/j.ces.2011.11.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Reusch JA, Anderson JK, Den Hartog DJ, Ebrahimi F, Schnack DD, Stephens HD, Forest CB. Experimental evidence for a reduction in electron thermal diffusion due to trapped particles. Phys Rev Lett 2011; 107:155002. [PMID: 22107297 DOI: 10.1103/physrevlett.107.155002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Indexed: 05/31/2023]
Abstract
New high time resolution measurements of the electron thermal diffusion χ(e) throughout the sawtooth cycle of the Madison Symmetric Torus reversed-field pinch have been made by utilizing the enhanced capabilities of the upgraded multipoint, multipulse Thomson scattering system. These measurements are compared to the χ(e) due to magnetic diffusion predicted by using information from a new high spectral resolution zero-β nonlinear resistive magnetohydrodynamic simulation performed, for the first time, at the Lundquist number of high current Madison Symmetric Torus plasmas (S≈4×10(6)). Agreement between the measured and predicted values is found only if the reduction in thermal diffusion due to trapped particles is taken into account.
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Affiliation(s)
- J A Reusch
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA.
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Abstract
AbstractIron alloys containing copper and nickel were irradiated at 288°C to a fluence of 4.63 × 1019 neutrons/cm2. Neutron irradiation produced defects which were observable by TEM in all of the iron alloys studied. The TEM analysis of the defects showed them to be interstitial dislocation loops with a < 100 > and a/2 < 111 > Burgers vectors. The size, the number density, and the Burgers vector of dislocations were affected by the alloy composition. The addition ofcopper and nickel decreased the dislocation loop size and increased the fraction of a/2 < 111 > loops. No voids or vacancy loops were observed in the irradiated iron alloys. The results are discussed in terms of dislocation loop nucleation and growth.
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Malo MS, Alam SN, Mostafa G, Zeller SJ, Johnson PV, Mohammad N, Chen KT, Moss AK, Ramasamy S, Faruqui A, Hodin S, Malo PS, Ebrahimi F, Biswas B, Narisawa S, Millán JL, Warren HS, Kaplan JB, Kitts CL, Hohmann EL, Hodin RA. Intestinal alkaline phosphatase preserves the normal homeostasis of gut microbiota. Gut 2010; 59:1476-84. [PMID: 20947883 DOI: 10.1136/gut.2010.211706] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS The intestinal microbiota plays a critical role in maintaining human health; however, the mechanisms governing the normal homeostatic number and composition of these microbes are largely unknown. Previously it was shown that intestinal alkaline phosphatase (IAP), a small intestinal brush border enzyme, functions as a gut mucosal defence factor limiting the translocation of gut bacteria to mesenteric lymph nodes. In this study the role of IAP in the preservation of the normal homeostasis of the gut microbiota was investigated. METHODS Bacterial culture was performed in aerobic and anaerobic conditions to quantify the number of bacteria in the stools of wild-type (WT) and IAP knockout (IAP-KO) C57BL/6 mice. Terminal restriction fragment length polymorphism, phylogenetic analyses and quantitative real-time PCR of subphylum-specific bacterial 16S rRNA genes were used to determine the compositional profiles of microbiotas. Oral supplementation of calf IAP (cIAP) was used to determine its effects on the recovery of commensal gut microbiota after antibiotic treatment and also on the colonisation of pathogenic bacteria. RESULTS IAP-KO mice had dramatically fewer and also different types of aerobic and anaerobic microbes in their stools compared with WT mice. Oral supplementation of IAP favoured the growth of commensal bacteria, enhanced restoration of gut microbiota lost due to antibiotic treatment and inhibited the growth of a pathogenic bacterium (Salmonella typhimurium). CONCLUSIONS IAP is involved in the maintenance of normal gut microbial homeostasis and may have therapeutic potential against dysbiosis and pathogenic infections.
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Affiliation(s)
- M S Malo
- Department of Surgery, Massachusetts General Hospital, Boston, MA 02114, USA.
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Ebrahimi F, Jungclas H, Happel S, Ensinger W, Béhé M, Bombard A, Zadmard R. Application of Extraction Chromatography for the Preparation of High Purity111In for Medical Use. Solvent Extraction and Ion Exchange 2010. [DOI: 10.1080/07366290903409142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Zhu P, Schnack DD, Ebrahimi F, Zweibel EG, Suzuki M, Hegna CC, Sovinec CR. Absence of complete finite-Larmor-radius stabilization in extended MHD. Phys Rev Lett 2008; 101:085005. [PMID: 18764628 DOI: 10.1103/physrevlett.101.085005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Indexed: 05/26/2023]
Abstract
The dominant finite-Larmour-radius (FLR) stabilization effects on interchange instability can be retained by taking into account the ion gyroviscosity or the generalized Ohm's law in an extended MHD model. However, recent simulations and theoretical calculations indicate that complete FLR stabilization of the interchange mode may not be attainable by ion gyroviscosity or the two-fluid effect alone in the framework of extended MHD. For a class of plasma equilibria in certain finite-beta or nonisentropic regimes, the critical wave number for complete FLR stabilization tends toward infinity.
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Affiliation(s)
- P Zhu
- Center for Plasma Theory and Computation, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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Ebrahimi F, Mikaili M, Estrada E, Nazeran H. Assessment of Itakura Distance as a valuable feature for computer-aided classification of sleep stages. ACTA ACUST UNITED AC 2008; 2007:3300-3. [PMID: 18002701 DOI: 10.1109/iembs.2007.4353035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Staging and detection of various states of sleep derived from EEG and other biomedical signals have proven to be very helpful in diagnosis, prognosis and remedy of various sleep related disorders. The time consuming and costly process of visual scoring of sleep stages by a specialist has always motivated researchers to develop an automatic sleep scoring system and the first step toward achieving this task is finding discriminating characteristics (or features) for each stage. A vast variety of these features and methods have been investigated in the sleep literature with different degrees of success. In this study, we investigated the performance of a newly introduced measure: the Itakura Distance (ID), as a similarity measure between EEG and EOG signals. This work demonstrated and further confirmed the outcomes of our previous research that the Itakura Distance serves as a valuable similarity measure to differentiate between different sleep stages.
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Affiliation(s)
- F Ebrahimi
- Department of Biomedical Engineering, Shahed University, Tehran, Iran
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Ebrahimi F, Mirnov VV, Prager SC, Sovinec CR. Momentum transport from current-driven reconnection in the reversed field pinch. Phys Rev Lett 2007; 99:075003. [PMID: 17930902 DOI: 10.1103/physrevlett.99.075003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Indexed: 05/25/2023]
Abstract
We calculate momentum transport from tearing fluctuations in a reversed field pinch with sheared flow, considering both the effect of a single tearing mode (through quasilinear theory and MHD computation) and multiple tearing modes (through nonlinear MHD computation). A single tearing mode transports momentum, via Maxwell and Reynolds stresses, more rapidly than classical viscous forces. Moreover, the transport is enhanced by nonlinear coupling of multiple modes.
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Affiliation(s)
- F Ebrahimi
- Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, and University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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Abstract
The cause for sudden reconnection in reversed field pinch plasmas is determined experimentally for two cases: large reconnection events (the sawtooth crash) and small reconnection events during improved confinement. We measure the term in the MHD equations which represents the driving (or damping) of edge tearing modes due to the axisymmetric magnetic field. The term is negative for large reconnection events (the modes are stable, implying that reconnection may be driven by nonlinear coupling to other modes) and positive for small reconnection events (modes are unstable, reconnection is spontaneous).
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Affiliation(s)
- S Choi
- University of Wisconsin-Madison and the Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, 1150 University Avenue, Madison, WI 53706, USA
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Ghaffarnejad M, Hejazi M, Ebrahimi F. The effect of abortion on outcome of subsequent pregnancy. Int J Gynaecol Obstet 2000. [DOI: 10.1016/s0020-7292(00)80565-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Ebrahimi F. The relationship between Alzheimer's disease and education as assayed by positron emission tomography and neuropsychological measures. Arch Clin Neuropsychol 1995. [DOI: 10.1016/0887-6177(95)92919-v] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Ebrahimi F, Castillo-Gomez J. The effect of plastic deformation on fracture morphology of the sigma phase in the NbTiAl system. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/0956-7151(92)90442-h] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
The fracture behavior of two types of urinary stones, namely struvite and calcium oxalate, during compression testing was studied. Scanning electron microscopy (SEM) was used to characterize the fracture surfaces. Both types of stone showed pseudo-plastic behavior as indicated by their load-displacement curve. The onset of nonlinear behavior was found to correspond to development of microcracks in the specimens. The compressive strength was defined as the stress calculated at the maximum load. In struvite samples, the maximum load corresponded with the development of large cracks parallel to the compressive axis. For oxalate stones a separation of the outer layer (crust) from the inner layer (core) marked the point of maximum load. The compressive strength of the struvite samples was found to depend on the orientation of lamellae relative to the loading axis. Struvite stones, when loaded parallel to the lamination direction showed a higher compressive strength than oxalate stones did. The fracture behavior and compressive strength of a model material (z-brick) were also characterized and compared to those of the urinary stones.
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Affiliation(s)
- F Ebrahimi
- Department of Materials Science and Engineering, University of Florida, Gainesville 32611
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