Ultrasound-guided needle tracking with deep learning: A novel approach with photoacoustic ground truth

Accurate needle guidance is crucial for safe and effective clinical diagnosis and treatment procedures. Conventional ultrasound (US)-guided needle insertion often encounters challenges in consistency and precisely visualizing the needle, necessitating the development of reliable methods to track the needle. As a powerful tool in image processing, deep learning has shown promise for enhancing needle visibility in US images, although its dependence on manual annotation or simulated data as ground truth can lead to potential bias or difficulties in generalizing to real US images. Photoacoustic (PA) imaging has demonstrated its capability for high-contrast needle visualization. In this study, we explore the potential of PA imaging as a reliable ground truth for deep learning network training without the need for expert annotation. Our network (UIU-Net), trained on ex vivo tissue image datasets, has shown remarkable precision in localizing needles within US images. The evaluation of needle segmentation performance extends across previously unseen ex vivo data and in vivo human data (collected from an open-source data repository). Specifically, for human data, the Modified Hausdorff Distance (MHD) value stands at approximately 3.73, and the targeting error value is around 2.03, indicating the strong similarity and small needle orientation deviation between the predicted needle and actual needle location. A key advantage of our method is its applicability beyond US images captured from specific imaging systems, extending to images from other US imaging systems.

Development of a general separation strategy by countercurrent chromatography using sanshools from Zanthoxylum bungeanum oleoresin as a case study

Three kinds of sanshools were separated from Zanthoxylum bungeanum oleoresin by the high-speed countercurrent chromatography. Sanshools are a series of amide compounds extracted from the Zanthoxylum bungeanum. Due to similar structures, polarities, and dissociation constants, it was challenging to select an appropriate solvent system for their complete separation by countercurrent chromatography. To address this challenge, a solvent-system-selection strategy was proposed to identify a relatively suitable solvent system. Additionally, a separation procedure incorporating multi-elution modes selection was established to separate similar compounds in a logical order. Ultimately, a solvent system comprising n-hexane:ethyl acetate:methanol:water in a ratio of 19:1:1:5.67 was selected. Three amide compounds with high purity were obtained through the use of recycling elution mode to improve separation resolution: hydroxy-ε-sanshool (8.4 mg; purity: 90.64%), hydroxy-α-sanshool (326.4 mg; purity: 98.96%), and hydroxy-β-sanshool (71.8 mg; purity: 98.26%) were obtained from 600 mg sanshool crude extract. The summarized solvent-system-selection strategy and separation procedure incorporating multi-elution modes may instruct countercurrent chromatography users, particularly novices, seeking to separate compounds with highly similar chemical properties. This article is protected by copyright. All rights reserved.

Android mobile-platform-based image reconstruction for photoacoustic tomography

Significance

In photoacoustic tomography (PAT), numerous reconstruction algorithms have been utilized to recover initial pressure rise distribution from the acquired pressure waves. In practice, most of these reconstructions are carried out on a desktop/workstation and the mobile-based reconstructions are far-flung. In recent years, mobile phones are becoming so ubiquitous, and most of them encompass a higher computing ability. Hence, realizing PAT image reconstruction on a mobile platform is intrinsic, and it will enhance the adaptability of PAT systems with point-of-care applications.

Aim

To implement PAT image reconstruction in Android-based mobile platforms.

Approach

For implementing PAT image reconstruction in Android-based mobile platforms, we proposed an Android-based application using Python to perform beamforming process in Android phones.

Results

The performance of the developed application was analyzed on different mobile platforms using both simulated and experimental datasets. The results demonstrate that the developed algorithm can accomplish the image reconstruction of in vivo small animal brain dataset in 2.4 s. Furthermore, the developed application reconstructs PAT images with comparable speed and no loss of image quality compared to that on a laptop. Employing a two-fold downsampling procedure could serve as a viable solution for reducing the time needed for beamforming while preserving image quality with minimal degradation.

Conclusions

We proposed an Android-based application that achieves image reconstruction on cheap, small, and universally available phones instead of relatively bulky expensive desktop computers/laptops/workstations. A beamforming speed of 2.4 s is achieved without hampering the quality of the reconstructed image.

A time-incorporated SOFA score-based machine learning model for predicting mortality in critically ill patients: A multicenter, real-world study

BACKGROUND

Organ dysfunction (OD) assessment is essential in intensive care units (ICUs). However, current OD assessment scores merely describe the number and the severity of each OD, without evaluating the duration of organ injury. The objective of this study is to develop and validate a machine learning model based on the Sequential Organ Failure Assessment (SOFA) score for the prediction of mortality in critically ill patients.

MATERIAL AND METHODS

Data from the eICU Collaborative Research Database and Medical Information Mart for Intensive Care (MIMIC) -III were mixed for model development. The MIMIC-IV and Nanjing Jinling Hospital Surgical ICU database were used as external test set A and set B, respectively. The outcome of interest was in-ICU mortality. A modified SOFA model incorporating time-dimension (T-SOFA) was stepwise developed to predict ICU mortality using extreme gradient boosting (XGBoost), support vector machine, random forest and logistic regression algorithms. Time-dimensional features were calculated based on six consecutive SOFA scores collected every 12 h within the first three days of admission. The predictive performance was assessed with the area under the receiver operating characteristic curves (AUROC) and calibration plot.

RESULTS

A total of 82,132 patients from the real-world datasets were included in this study, and 7,494 patients (9.12%) died during their ICU stay. The T-SOFA M3 that incorporated the time-dimension features and age, using the XGBoost algorithm, significantly outperformed the original SOFA score in the validation set (AUROC 0.800 95% CI [0.787-0.813] vs. 0.693 95% CI [0.678-0.709], p < 0.01). Good discrimination and calibration were maintained in the test set A and B, with AUROC of 0.803, 95% CI [0.791-0.815] and 0.830, 95% CI [0.789-0.870], respectively.

CONCLUSIONS

The time-incorporated T-SOFA model could significantly improve the prediction performance of the original SOFA score and is of potential for identifying high-risk patients in future clinical application.

Inconsistency-Aware Uncertainty Estimation for Semi-Supervised Medical Image Segmentation

In semi-supervised medical image segmentation, most previous works draw on the common assumption that higher entropy means higher uncertainty. In this paper, we investigate a novel method of estimating uncertainty. We observe that, when assigned different misclassification costs in a certain degree, if the segmentation result of a pixel becomes inconsistent, this pixel shows a relative uncertainty in its segmentation. Therefore, we present a new semi-supervised segmentation model, namely, conservative-radical network (CoraNet in short) based on our uncertainty estimation and separate self-training strategy. In particular, our CoraNet model consists of three major components: a conservative-radical module (CRM), a certain region segmentation network (C-SN), and an uncertain region segmentation network (UC-SN) that could be alternatively trained in an end-to-end manner. We have extensively evaluated our method on various segmentation tasks with publicly available benchmark datasets, including CT pancreas, MR endocardium, and MR multi-structures segmentation on the ACDC dataset. Compared with the current state of the art, our CoraNet has demonstrated superior performance. In addition, we have also analyzed its connection with and difference from conventional methods of uncertainty estimation in semi-supervised medical image segmentation.

Interferometric imaging of thermal expansion for temperature control in retinal laser therapy

Precise control of the temperature rise is a prerequisite for proper photothermal therapy. In retinal laser therapy, the heat deposition is primarily governed by the melanin concentration, which can significantly vary across the retina and from patient to patient. In this work, we present a method for determining the optical and thermal properties of layered materials, directly applicable to the retina, using low-energy laser heating and phase-resolved optical coherence tomography (pOCT). The method is demonstrated on a polymer-based tissue phantom heated with a laser pulse focused onto an absorbing layer buried below the phantom's surface. Using a line-scan spectral-domain pOCT, optical path length changes induced by the thermal expansion were extracted from sequential B-scans. The material properties were then determined by matching the optical path length changes to a thermo-mechanical model developed for fast computation. This method determined the absorption coefficient with a precision of 2.5% and the temperature rise with a precision of about 0.2°C from a single laser exposure, while the peak did not exceed 8°C during 1 ms pulse, which is well within the tissue safety range and significantly more precise than other methods.

Vertical-junction photodiodes for smaller pixels in retinal prostheses

Objective.To restore central vision in patients with atrophic age-related macular degeneration, we replace the lost photoreceptors with photovoltaic pixels, which convert light into current and stimulate the secondary retinal neurons. Clinical trials demonstrated prosthetic acuity closely matching the sampling limit of the 100 μm pixels, and hence smaller pixels are required for improving visual acuity. However, with smaller flat bipolar pixels, the electric field penetration depth and the photodiode responsivity significantly decrease, making the device inefficient. Smaller pixels may be enabled by (1) increasing the diode responsivity using vertical p-n junctions and (2) directing the electric field in tissue vertically. Here, we demonstrate such novel photodiodes and test the retinal stimulation in a vertical electric field.Approach.Arrays of silicon photodiodes of 55, 40, 30, and 20 μm in width, with vertical p-n junctions, were fabricated. The electric field in the retina was directed vertically using a common return electrode at the edge of the devices. Optical and electronic performance of the diodes was characterized in-vitro, and retinal stimulation threshold measured by recording the visually evoked potentials (VEPs) in rats with retinal degeneration.Main results.The photodiodes exhibited sufficiently low dark current (<10 pA) and responsivity at 880 nm wavelength as high as 0.51 A/W, with 85% internal quantum efficiency, independent of pixel size. Field mapping in saline demonstrated uniformity of the pixel performance in the array. The full-field stimulation threshold was as low as 0.057±0.029 mW/mm²with 10 ms pulses, independent of pixel size.Significance.Photodiodes with vertical p-n junctions demonstrated excellent charge collection efficiency independent of pixel size, down to 20 μm. Vertically-oriented electric field provides a stimulation threshold that is independent of pixel size. These results are the first steps in validation of scaling down the photovoltaic pixels for subretinal stimulation.

Mechanisms of Light-Induced Deformations in Photoreceptors

Biological cells deform on a nanometer scale when their transmembrane voltage changes, an effect that has been visualized during the action potential using quantitative phase imaging. Similar changes in the optical path length have been observed in photoreceptor outer segments after a flash stimulus via phase-resolved optical coherence tomography. These optoretinograms reveal a fast, millisecond-scale contraction of the outer segments by tens of nanometers, followed by a slow (hundreds of milliseconds) elongation reaching hundreds of nanometers. Ultrafast measurements of the contractile response using line-field phase-resolved optical coherence tomography show a logarithmic increase in amplitude and a decreasing time to peak with increasing stimulus intensity. We present a model that relates the early receptor potential to these deformations based on the voltage-dependent membrane tension-the mechanism observed earlier in neurons and other electrogenic cells. The early receptor potential is caused by conformational changes in opsins after photoisomerization, resulting in the fractional shift of the charge across the disk membrane. Lateral repulsion of the ions on both sides of the membrane affects its surface tension and leads to its lateral expansion. Because the volume of the disks does not change on a millisecond timescale, their lateral expansion leads to an axial contraction of the outer segment. With increasing stimulus intensity and the resulting tension, the area expansion coefficient of the disk membrane also increases as thermally induced fluctuations are pulled flat, resisting further expansion. This leads to the logarithmic saturation observed in measurements as well as the peak shift in time. This imaging technique therefore relates the structural changes in the photoreceptor to the underlying neurological function of transducing light into electrical signals. Such label-free optical monitoring of neural activity using fast interferometry may be applicable not only to optoretinography but also to neuroscience in general.

The optoretinogram reveals the primary steps of phototransduction in the living human eye

Photoreceptors initiate vision by converting photons to electrical activity. The onset of the phototransduction cascade is marked by the isomerization of photopigments upon light capture. We revealed that the onset of phototransduction is accompanied by a rapid (<5 ms), nanometer-scale electromechanical deformation in individual human cone photoreceptors. Characterizing this biophysical phenomenon associated with phototransduction in vivo was enabled by high-speed phase-resolved optical coherence tomography in a line-field configuration that allowed sufficient spatiotemporal resolution to visualize the nanometer/millisecond-scale light-induced shape change in photoreceptors. The deformation was explained as the optical manifestation of electrical activity, caused due to rapid charge displacement following isomerization, resulting in changes of electrical potential and surface tension within the photoreceptor disc membranes. These all-optical recordings of light-induced activity in the human retina constitute an optoretinogram and hold remarkable potential to reveal the biophysical correlates of neural activity in health and disease.

High-speed interferometric imaging reveals dynamics of neuronal deformation during the action potential

Neurons undergo nanometer-scale deformations during action potentials, and the underlying mechanism has been actively debated for decades. Previous observations were limited to a single spot or the cell boundary, while movement across the entire neuron during the action potential remained unclear. Here we report full-field imaging of cellular deformations accompanying the action potential in mammalian neuron somas (-1.8 to 1.4 nm) and neurites (-0.7 to 0.9 nm), using high-speed quantitative phase imaging with a temporal resolution of 0.1 ms and an optical path length sensitivity of <4 pm per pixel. The spike-triggered average, synchronized to electrical recording, demonstrates that the time course of the optical phase changes closely matches the dynamics of the electrical signal. Utilizing the spatial and temporal correlations of the phase signals across the cell, we enhance the detection and segmentation of spiking cells compared to the shot-noise-limited performance of single pixels. Using three-dimensional (3D) cellular morphology extracted via confocal microscopy, we demonstrate that the voltage-dependent changes in the membrane tension induced by ionic repulsion can explain the magnitude, time course, and spatial features of the phase imaging. Our full-field observations of the spike-induced deformations shed light upon the electromechanical coupling mechanism in electrogenic cells and open the door to noninvasive label-free imaging of neural signaling.

Trichostatin A exerts anti-inflammation functions in LPS-induced acute lung injury model through inhibiting TNF-α and upregulating micorRNA-146a expression

OBJECTIVE

Acute lung disease is characterized by inflammation. This research aimed to investigate effect of trichostatin A (TSA) on microRNA-146a (miR-146a) and tumor necrosis factor α (TNF-α) in lipopolysaccharide (LPS)-induced alveolar macrophage injury model.

MATERIALS AND METHODS

Rat alveolar macrophage, NR8383, was cultured and induced using LPS to establish acute lung injury model in vitro level. Cell Counting Kit-8 (CCK-8) assay was used to determine cell viability of NR8383 cells. TSA was administrated to LPS-induced NR8383 cells. Quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) assay was utilized to evaluate TNF-α and miR-146a mRNA expression in LPS and/or TSA treated NR8383 cells. Enzyme-link immunosorbent assay (ELISA) was used to examine TNF-α levels.

RESULTS

This study selected 1 ng/ml and 10 ng/ml TSA as the optimal concentrations for treating NR8383 cells. LPS-induced acute lung injury model was successfully established. TSA administration significantly enhanced accounts of LPS-stimulated NR8383 cells. LPS induction significantly increased miR-146a mRNA expression in NR8383 cells compared to NR8383 cells (p<0.05). TSA administration significantly reduced the levels of TNF-α in LPS-induced NR8383 cells compared to those in LPS-induced NR8383 cells (p<0.05). TSA administration significantly enhanced miR-146a expression in LPS-induced NR8383 cells compared to that in LPS-induced NR8383 cells (p<0.05).

CONCLUSIONS

TSA administration exerted anti-inflammation functions in LPS-induced acute lung injury model in vitro, which might be triggered by inhibiting TNF-α molecule and upregulating miR-146a expression. The present data hint that TSA could be considered as a potential therapeutic agent for treating acute lung injury.

Moving beyond individual choice in policies to reduce health inequalities: the integration of dynamic with individual explanations

Background

A strong focus on individual choice and behaviour informs interventions designed to reduce health inequalities in the UK. We review evidence for wider mechanisms from a range of disciplines, demonstrate that they are not yet impacting on programmes, and argue for their systematic inclusion in policy and research.

Methods

We identified potential mechanisms relevant to health inequalities and their amelioration from different disciplines and analysed six policy documents published between 1976 and 2010 using Bacchi's 'What's the problem represented to be?' framework for policy analysis.

Results

We found substantial evidence of supra-individualistic and relational mechanisms relevant to health inequalities from sociology, history, biology, neuroscience, philosophy and psychology. Policy documents sometimes expressed these mechanisms in policy rhetoric but rarely in policy recommendations, which continue to focus on individual behaviour.

Discussion

Current evidence points to the potential of systematically applying broader thinking about causal mechanisms, beyond individual choice and responsibility, to the design, implementation and evaluation of policies to reduce health inequalities. We provide a set of questions designed to enable critique of policy discussions and programmes to ensure that these wider mechanisms are considered.

Selective Recovery of n-Butanol from Aqueous Solutions with Functionalized Poly(epoxide ionic liquid)-Based Polyurethane Membranes by Pervaporation

In this study, hydroxyl-terminated polybutadiene-poly(epoxide ionic liquid)-poly(urethane urea) (HTPB-PEIL-PU) membranes, HTPB-PEIL1-PU and HTPB-PEIL2-PU, were prepared by the reaction of functionalized PEIL, poly(1-methylimidazole-3-methyl-ethyloxy)hexafluorophosphate or poly(1-methylimidazole-3-methyl-ethyloxy)bistrifluoromethanesulfonimidate, respectively, with HTPB using 4,4'-diphenylmethane diisocyanate (MDI) as the chain extender. The HTPB-PEIL-PU and HTPB membranes were investigated for the selective recovery of n-butanol from aqueous solutions by pervaporation. PEIL was confirmed to be successfully embedded in the PU membranes by ¹H NMR, Fourier transform infrared, and differential scanning calorimetry measurements. According to our mechanical measurements, the HTPB-PEIL-PU membranes retain the mechanical properties of the original PU membrane. PEIL was shown to enhance the diffusion rate of n-butanol significantly based on swelling behavior tests. The pervaporation flux through the HTPB-PEIL1-PU membrane increased with increasing feed temperature and feed concentration. In contrast, the separation factor of the HTPB-PEIL1-PU membrane increased with increasing feed temperature but decreased with increasing feed concentration. In addition, the HTPB-PEIL2-PU membrane exhibited an optimal separation factor of up to 29.2 at a feed concentration of 3% and a feed temperature of 70 °C, which is superior to that (22.7) through pure HTPB membranes. Furthermore, the HTPB-PEIL1-PU and HTPB-PEIL2-PU membranes show better long-term stability than other supported ionic liquid membranes.

High-precision calibration method for shear ratio based on the shearing wavefront feature extraction of a phase plate

A new method based on the shearing wavefront feature extraction (SWFE) of a phase plate is proposed to accurately estimate the shear ratio of the system. The relationship between the shear ratio of a quadriwave lateral shearing interferometer based on a randomly encoded hybrid grating (REHG) and the measurement sensitivity, dynamic range, and wavefront retrieval accuracy is analyzed to provide a theoretical guidance for practical application. The simulation result of the SWFE method shows that the relative error of the shear ratio value is about 1.8×10^-3, within the acceptable range of the system. In the experiment, two fused quartz phase plates etched with step change edge grooves were introduced to calibrate the shear ratio of the REHG wavefront diagnosis system. Then, the etching depths of these two phase plates and the figure error of a spherical surface were characterized by the REHG. A comparison with a ZYGO GPI interferometer exhibits that the testing results by the REHG are highly precise, which further confirms the effectiveness of the SWFE method in the shear ratio calibration. This shear ratio calibration method is available for similar kind of shearing interferometric wavefront sensor.

Full-field interferometric imaging of propagating action potentials

Currently, cellular action potentials are detected using either electrical recordings or exogenous fluorescent probes that sense the calcium concentration or transmembrane voltage. Ca imaging has a low temporal resolution, while voltage indicators are vulnerable to phototoxicity, photobleaching, and heating. Here, we report full-field interferometric imaging of individual action potentials by detecting movement across the entire cell membrane. Using spike-triggered averaging of movies synchronized with electrical recordings, we demonstrate deformations up to 3 nm (0.9 mrad) during the action potential in spiking HEK-293 cells, with a rise time of 4 ms. The time course of the optically recorded spikes matches the electrical waveforms. Since the shot noise limit of the camera (~2 mrad/pix) precludes detection of the action potential in a single frame, for all-optical spike detection, images are acquired at 50 kHz, and 50 frames are binned into 1 ms steps to achieve a sensitivity of 0.3 mrad in a single pixel. Using a self-reinforcing sensitivity enhancement algorithm based on iteratively expanding the region of interest for spatial averaging, individual spikes can be detected by matching the previously extracted template of the action potential with the optical recording. This allows all-optical full-field imaging of the propagating action potentials without exogeneous labels or electrodes.

High pretreatment plasma D-dimer predicts poor survival of colorectal cancer: insight from a meta-analysis of observational studies

D-dimer, one of the canonical markers of hypercoagulability, was reported to be a potential prognostic marker of colorectal cancer. However, an inconsistent conclusion existed in several published studies. Thus, we performed this meta-analysis to provide a comprehensive insight into the prognostic role for pretreatment D-dimer in colorectal cancer. Six databases (English: Pubmed, Embase and Web of Science; Chinese: CNKI, Wangfang and VIP) were utilized for the literature retrieval. Hazard ratio (HR) was pooled by Stata 12.0. A total of fifteen studies (2283 cases) corresponded to this meta-analysis and provided available data to evaluate the prognostic role of D-dimer for colorectal cancer. The pooled HR reached 2.167 (95%. CI (confidence interval): 1.672-2.809, P < 0.001) utilizing random effect model due to obvious heterogeneity among the included studies (I²: 73.3%; P < 0.001). To explore the heterogeneity among the studies, we conducted a sensitivity analysis and found a heterogeneous study. After removing it, the heterogeneity reduced substantially (I²: 0%; P = 0.549) and we obtained a more convincing result by fixed effect model (HR = 2.143, 95% CI = 1.922-2.390, P < 0.001, 14 studies with 2179 cases). In summary, high pretreatment plasma D-dimer predicts poor survival of colorectal cancer based on the current evidence. Further prospective researches are necessary to confirm the role of D-dimer in colorectal cancer.

Long-term outcomes of peroral endoscopic myotomy for patients with achalasia: a retrospective single-center study

Peroral endoscopic myotomy (POEM) has been widely applied to the treatment of achalasia. The aim of this study is to retrospectively investigate the long-term outcome of POEM in patients with achalasia. Patients undergoing POEM at our center with a minimum follow-up of 3 years were enrolled in this study. Relief of patients' symptom was defined as the primary outcome. Secondary outcomes included lower esophageal sphincter pressure, esophageal emptying, symptoms relapse, and clinical reflux adverse events. The Chi-square test was performed to determine the potential predictors of surgical failure. Sixty-seven patients (aged 40.7 ± 15.3 years) were recruited in the study, with a mean follow-up period of 40.1 ± 2.8 months. At the final follow-up, the median Eckardt score reduced from 7.6 ± 2.3 preoperatively to 1.9 ± 1.7 (P < 0.001), the lower esophageal sphincter pressure was reduced from 35.4 ± 13.7 mmHg preoperatively to 8.9 ± 4.1 mmHg (P < 0.001), and the height of the barium column at 5 min after barium swallowed was reduced from 9.7 ± 1.6 cm preoperatively to 2.9 ± 2.1 cm (P < 0.001). Eight patients had symptoms relapse and nine patients developed reflux esophagitis. Type III achalasia was found to be indicative of surgical failure. POEM was a promising treatment for patients with achalasia, which can yield a long-term relief of the symptom and a low rate of clinical reflux adverse events.

Low nanomolar concentrations of Cucurbitacin-I induces G2/M phase arrest and apoptosis by perturbing redox homeostasis in gastric cancer cells in vitro and in vivo

Cucurbitacin-I (Cu-I, also known as Elatericin B or JSI-124) is developed to inhibit constitutive and abnormal activation of STAT3 in many cancers, demonstrating a potent anticancer activity by targeting disruption of STAT3 function. Here, we for the first time systematically studied the underlying molecular mechanisms of Cu-I-induced gastric cancer cell death both in vitro and in vivo. In our study, we show that Cu-I markedly inhibits gastric cancer cell growth by inducing G2/M phase cell cycle arrest and apoptosis at low nanomolar concentrations via a STAT3-independent mechanism. Notably, Cu-I significantly decreases intracellular GSH/GSSG ratio by inhibiting NRF2 pathway to break cellular redox homeostasis, and subsequently induces the expression of GADD45α in a p53-independent manner, and activates JNK/p38 MAPK signaling. Interestingly, Cu-I-induced GADD45α and JNK/p38 MAPK signaling form a positive feedback loop and can be reciprocally regulated by each other. Therefore, the present study provides new insights into the mechanisms of antitumor effects of Cu-I, supporting Cu-I as an attractive therapeutic drug in gastric cancer by modulating the redox balance.

Scalable synthesis of cubic Cu1.4S nanoparticles with long-term stability by laser ablation of salt powder

An intensive laser was employed to irradiate a salt target, and the fierce synthetic conditions result in a large amount of Cu_1.4S nanoparticles with exceptional long-term stability.

Practical phase unwrapping of interferometric fringes based on unscented Kalman filter technique

A phase unwrapping algorithm for interferometric fringes based on the unscented Kalman filter (UKF) technique is proposed. The algorithm can bring about accurate phase unwrapping and good noise suppression simultaneously by incorporating the true phase and its derivative in the state vector estimation through the UKF process. Simulations indicate that the proposed algorithm has better accuracy than some widely employed phase unwrapping approaches in the same noise condition. Also, the time consumption of the algorithm is reasonably acceptable. Applications of the algorithm in our different optical interferometer systems are provided to demonstrate its practicability with good performance. We hope this algorithm can be a practical approach that can help to reduce the systematic errors significantly induced by phase unwrapping process for interferometric measurements such as wavefront distortion testing, surface figure testing of optics, etc.

Biological and immunological characterization of norovirus major capsid proteins from three different genotypes

Noroviruses (NoVs) are the leading cause of non-bacterial acute gastroenteritis worldwide. Due to a lack of cell culture system and animal model, our understanding of NoVs has been lagging behind. In this study, NoV major capsid proteins (VP1) from three different genotypes (GI.2, GII.3 and GII.4) were expressed by using recombinant baculovirus expression system and which led to successful assembly of virus-like particles (VLPs). The receptor binding patterns of three kinds of VLPs were characterized by using synthetic and salivary HBGA-VLP binding assay. Cross-reactivity and cross-blocking activity of rabbit hyperimmune sera against these VLPs were determined by ELISA/Western blot analysis and saliva-VLP binding blockade assay, respectively. Expression of the major capsid proteins from three genotypes all led to smaller VLPs in dominance when sf9 cells were cultured in suspension, which was in consistence with our previous report. These smaller VLPs were used for in vitro synthetic and salivary HBGA-VLP binding and binding blockade assays. VLPs from GII.3 strain exhibited no binding to all synthetic HBGAs and saliva samples tested while VLPs from GI.2 and GII.4 strain showed similar binding pattern and bound to all salivary HBGAs tested. Rabbit anti-GII.3 VLPs hyperimmune serum didn't block the binding of GI.2 and GII.4 VLPs to salivary HBGAs while rabbit anti-GI.2 VLP hyperimmune serum blocked the binding of GII.4 VLPs to salivary HBGAs but not vice versa. Our results provide further evidence indirectly in support of presence of other factors involved in receptor binding other than HBGAs for NoVs, and demonstrate poor cross-blocking activities of antibodies against VLPs within or across genogroups.

General measurement of optical system aberrations with a continuously variable lateral shear ratio by a randomly encoded hybrid grating

A general lateral shearing interferometry method to measure the wavefront aberrations with a continuously variable shear ratio by the randomly encoded hybrid grating (REHG) is proposed. The REHG consists of a randomly encoded binary amplitude grating and a phase chessboard. Its Fraunhofer diffractions contain only four orders which are the ±1 orders in two orthogonal directions due to the combined modulation of the amplitude and phase. As a result, no orders selection mask is needed for the REHG and the shear ratio is continuously variable, which is beneficial to the variation of sensitivity and testing range for different requirements. To determine the fabrication tolerance of this hybrid grating, the analysis of the effects of different errors on the diffraction intensity distributions is carried out. Experiments have shown that the testing method can achieve a continuously variable shear ratio with the same REHG, and the comparison with a ZYGO GPI interferometer exhibits that the aberration testing method by the REHG is highly precise and also has a good repeatability. This testing method by the REHG is available for general use in testing the aberrations of different optical systems in situ.

Prevailing Sydney like Norovirus GII.4 VLPs induce systemic and mucosal immune responses in mice

The newly emerged Norovirus (NoV) Sydney 2012 strain has been sweeping all over the world, causing acute non-bacterial gastroenteritis in adults and children. Due to a lack of cell culture system, virus like particles (VLPs) has been assembled and used as vaccine candidates in preclinical and clinical studies. Expression of the major capsid protein of NoVs using recombinant baculovirus expression system in Sf9 cells leads to formation of VLPs that are morphologically and antigenically similar to true virions. In this study, VLPs were successfully produced using the VP1 of Sydney-2012-like strain and its immunogenicity was evaluated by different routes and its capability in inducing mucosal immune responses in the presence and absence of adjuvants in BALB/c mice. Administration of NoV VLPs in the presence of Al(OH)3 or monophosphoryl lipid A (MPL-A) led to high titers of VLP-specific IgG antibodies. Administration of VLPs orally in the presence of cholera toxin subunit B (CTB) didn't enhance mucosal immune response as less fecal IgA positive mice were observed when compared with those given VLPs only. Our study represents the first immunogenicity study of VLPs derived from current pandemic Sydney 2012 strain and which might have implications in the development of NoVs vaccine in china.

Quadriwave lateral shearing interferometer based on a randomly encoded hybrid grating

A compact quadriwave lateral shearing interferometer (QWLSI) with strong adaptability and high precision is proposed based on a novel randomly encoded hybrid grating (REHG). By performing the inverse Fourier transform of the desired ±1 Fraunhofer diffraction orders, the amplitude and phase distributions of the ideally calculated quadriwave grating can be obtained. Then a phase chessboard is introduced to generate the same phase distribution, while the amplitude distribution can be achieved using the randomly encoding method by quantizing the radiant flux on the ideal quadriwave grating. As the Faunhofer diffraction of the REHG only contains the ±1 orders, no order selection mask is ever needed for the REHG-LSI. The simulations and the experiments show that the REHG-LSI exhibits strong adaptability, nice repeatability, and high precision.

Common-path and compact wavefront diagnosis system based on cross grating lateral shearing interferometer

A common-path and compact wavefront diagnosis system for both continuous and transient wavefronts measurement is proposed based on cross grating lateral shearing interferometer (CGLSI). Derived from the basic CGLSI configuration, this system employs an aplanatic lens to convert the wavefront under test into a convergent beam, which makes it possible for CGLSI to test the wavefront of collimated beams. A geometrical optics model for grating pitch determination and a Fresnel diffraction model for order selection mask design are presented. Then a detailed analysis about the influence of the grating pitch, the distance from the cross grating to the order selection mask and the numerical aperture of the aplanatic lens on the system error is made, and a calibration method is proposed to eliminate the system error. In addition, the differential Zernike polynomials fitting method is introduced for wavefront retrieval. Before our experiment, we have designed several grating pitches and their corresponding order selection mask parameters. In the final comparative experiment with ZYGO interferometer, the wavefront diagnosis system exhibits both high precision and repeatability.

Guided bone regeneration using acellular bovine pericardium in a rabbit mandibular model: in-vitro and in-vivo studies

BACKGROUND AND OBJECTIVE

To investigate the feasibility of acellular bovine pericardium (BP) for guided bone regeneration (GBR) in vitro and in vivo. The success of GBR relies on the fact that various cellular components possess different migration rates into the defect site and that a barrier membrane plays a significant role in these processes.

MATERIAL AND METHODS

BP membrane was isolated and decellularized using an enzymatic method. The microarchitecture, mechanical properties, cytotoxicity and cell chemotaxis properties of the acellular BP were evaluated in vitro, and the in-vivo efficacy of the acellular BP was also investigated in a rabbit mandibular model.

RESULTS

The acellular BP membrane possessed an interconnected fibrous structure. Glutaraldehyde (GA) treatment was efficient for enhancement of the mechanical properties of the acellular BP bur and resulted in negligible cytotoxicity. After 16 wk, standardized osseous defects created in the rabbit mandible, and covered with acellular BP, were associated with an enhanced deposition of mineralized tissue when compared with defects left to spontaneous healing.

CONCLUSION

GA-treated acellular BP is promising as a barrier membrane for GBR for further in-vivo and clinical studies.

Off-axis cyclic radial shearing interferometer for measurement of centrally blocked transient wavefront

An off-axis cyclic radial shearing interferometer (OCRSI) to test a centrally blocked transient wavefront is proposed. Based on the standard cyclic radial shearing interferometer (CRSI), the OCRSI consists of a beam splitter, two folding mirrors, and a Galilean telescope. With the same but reversal tilt introduced to the two mirrors in OCRSI, the shearing interferogram can be obtained even when the central part of the test aperture is blocked. An improved wavefront retrieval method for OCRSI is employed, and a method to obtain the laterally sheared amount between the contracted and expanded beams is proposed. Numerical simulation and comparison experiments with a ZYGO GPI interferometer demonstrate that the OCRSI exhibits high precision and nice repeatability.

Retrieval and analysis of a polarized high-spectral-resolution lidar for profiling aerosol optical properties

Taking advantage of the broad spectrum of the Cabannes-Brillouin scatter from atmospheric molecules, the high spectral resolution lidar (HSRL) technique employs a narrow spectral filter to separate the aerosol and molecular scattering components in the lidar return signals and therefore can obtain the aerosol optical properties as well as the lidar ratio (i.e., the extinction-to-backscatter ratio) which is normally selected or modeled in traditional backscatter lidars. A polarized HSRL instrument, which employs an interferometric spectral filter, is under development at the Zhejiang University (ZJU), China. In this paper, the theoretical basis to retrieve the aerosol lidar ratio, depolarization ratio and extinction and backscatter coefficients, is presented. Error analyses and sensitivity studies have been carried out on the spectral transmittance characteristics of the spectral filter. The result shows that a filter that has as small aerosol transmittance (i.e., large aerosol rejection rate) and large molecular transmittance as possible is desirable. To achieve accurate retrieval, the transmittance of the spectral filter for molecular and aerosol scattering signals should be well characterized.

Tomographic reconstruction of three-dimensional refractive index fields by use of a regularized phase-tracking technique and a polynomial approximation method

We present a complete data-processing procedure for quantitative reconstruction of three-dimensional (3D) refractive index fields from limited multidirectional interferometric data. The proposed procedure includes two parts: (1) extraction of the projection data from limited multidirectional interferograms by a regularized phase-tracking technique and wavefront fitting and (2) reconstruction of the 3D refractive index fields by a modified polynomial approximation method. It has been shown that the procedure gives a satisfactory solution to the reconstruction issue in interferometric tomography, from the initial projection data extraction to the final image reconstruction. Computer simulation and experimental results are both presented.

Demodulation of a single-image interferogram using a Zernike-polynomial-based phase-fitting technique with a differential evolution algorithm

We propose a simple and robust polynomial-based phase-fitting (PPF) technique for single interferogram demodulation. Based on the smoothness assumption, the method employs a set of Zernike polynomials (ZPs) to fit the phase and estimates the expansion coefficients using a global optimization algorithm, i.e., differential evolution. The fitting order of the ZPs and the bounds of the coefficients can be intuitively determined according to the shape and number of fringes of the interferogram. Different from classical methods that need predefined scanning paths to guide the phase estimator, the PPF demodulates an interferogram globally and is insensitive to local defects, which allows it to deal with very noisy interferograms. Moreover, as the PPF gives the reconstructed phase by use of the ZPs, no further phase-unwrapping or wavefront-fitting procedures are needed. Experimental results have demonstrated the robustness and effectiveness of the method.

Parametric positioning of a continuous crystal PET detector with depth of interaction decoding

Here we demonstrate a parametric positioning method on a continuous crystal detector. Three different models for the light distribution were tested. Diagnosis of the residues showed that the parametric model fits the experimental data better than Gaussian and Cauchy models in our particular experimental setup. Based on the correlation between the spread and the peak value of the light distribution model with the depth of interaction (DOI), we were able to estimate the three-dimensional position of a scintillation event. On our continuous miniature crystal element (cMiCE) detector module with 8 mm thick LYSO crystal, the intrinsic spatial resolution is 1.06 mm at the center and 1.27 mm at the corner using a maximum-likelihood estimation (MLE) method and the parametric model. The DOI resolution (full width at half maximum) is estimated to be approximately 3.24 mm. The positioning method using the parametric model outperformed the Gaussian and Cauchy models, in both MLE and weighted least-squares (WLS) fitting methods. The key feature of this technique is that it requires very little calibration of the detector, but still retains high resolution and high sensitivity.

[The role of norepinephrine in down-regulation of visceral sensitivity in rats deprived of rapid eye movement sleep]

OBJECTIVE

To investigate the role of norepinephrine in the down-regulated visceral sensitivity of rats deprived of rapid eye movement (REM) sleep.

METHODS

Twenty-four male Sprague-Dawley rats were randomly divided into 3 groups: cage-yoked rats as control (YC), rats with REM sleep deprivation (SD) and rats with yohimbine administered intraperitoneally after REM sleep deprivation (YSD). Flower pot technique was employed to make sleep deprivation model. YSD group was given yohimbine intraperitoneally at the 48th hour after REM sleep deprivation. After both SD and YSD groups had completed these processes, rats of all the three groups were given colorectal distension (CRD) and electromyogram (EMG) was recorded at the same time. The number of discharges of EMG and the threshold of pain perception of the rats were observed to evaluate the visceral sensitivity. The thalamus, rectum and distal colon were taken after CRD; MAO-mRNA and TH-mRNA in three tissues were detected with RT-PCR.

RESULTS

On 48th hour, the number of discharges of EMG in 10 seconds responding to CRD in group SD was significantly less than that in group YC and the threshold of pain perception in group SD was higher than that in group YC (P < 0.05). The number of discharge of EMG in group YSD was significantly more than that in group SD (P < 0.05). The expression of MAO-mRNA in group SD was lower than that in group YC (P < 0.05) and the expression of TH-mRNA in group SD was higher than that in group YC (P < 0.05).

CONCLUSIONS

The visceral sensitivity in rats is down-regulated by REM sleep deprivation, which can increase synthesis of norepinephrine. Norepinephrine can modulate visceral sensitivity.