Phase transition in bilayer MoS2under tensile loading: a molecular dynamics study.

Molybdenum disulfide (MoS2), especially single-layer MoS2, has been experimentally and computationally discovered to exist in several different polymorphs exhibiting various electronic and mechanical properties. The morphology of MoS2can be tuned through strain engineering. Molecular dynamics simulations are conducted to systematically study the phase transition of single-layer MoS2and bilayer MoS2under the uniaxial tensile condition at room temperature. The roles of edge and S-line vacancy are investigated. Phase transitions are always triggered near the edge and vacancy sites. The initiation of the metastable T″ phase can release the tensile stress in the lattice, followed by I4/mmm phase initiation, regardless of the edge conditions. The growth of the I4/mmm phase can cause the local buckling of the MoS2plane. With a tilted S-line vacancy, I4/mmm phase is first initiated to reduce the local shear stress accumulated near the vacancy line. Overall, the phase transition mechanism of single layer and bilayer MoS2under the uniaxial tensile loading is provided, which guides the future strain engineering of MoS2in nanoelectronics applications.

Four-Stage Multi-Physics Simulations to Assist Temperature Sensor Design for Industrial-Scale Coal-Fired Boiler.

The growth of renewable energy sources presents a pressing challenge to the operation and maintenance of existing fossil fuel power plants, given that fossil fuel remains the predominant fuel source, responsible for over 60% of electricity generation in the United States. One of the main concerns within these fossil fuel power plants is the unpredictable failure of boiler tubes, resulting in emergency maintenance with significant economic and societal consequences. A reliable high-temperature sensor is necessary for in situ monitoring of boiler tubes and the safety of fossil fuel power plants. In this study, a comprehensive four-stage multi-physics computational framework is developed to assist the design, optimization installation, and operation of the high-temperature stainless-steel and quartz coaxial cable sensor (SSQ-CCS) for coal-fired boiler applications. With the consideration of various operation conditions, we predict the distributions of flue gas temperatures within coal-fired boilers, the temperature correlation between the boiler tube and SSQ-CCS, and the safety of SSQ-CCS. With the simulation-guided sensor installation plan, the newly designed SSQ-CCSs have been employed for field testing for more than 430 days. The computational framework developed in this work can guide the future operation of coal-fired plants and other power plants for the safety prediction of boiler operations.

A Feasibility Study on Proton Range Monitoring Using 13N Peak in Inhomogeneous Targets.

Proton irradiations are highly sensitive to spatial variations, mainly due to their high linear energy transfer (LET) and densely ionizing nature. In realistic clinical applications, the targets of ionizing radiation are inhomogeneous in terms of geometry and chemical composition (i.e., organs in the human body). One of the main methods for proton range monitoring is to utilize the production of proton induced positron emitting radionuclides; these could be measured precisely with positron emission tomography (PET) systems. One main positron emitting radionuclide that could be used for proton range monitoring and verification was found to be 13N that produces a peak close to the Bragg peak. In the present work, we have employed the Monte Carlo method and Spectral Analysis (SA) technique to investigate the feasibility of utilizing the 13N peak for proton range monitoring and verification in inhomogeneous targets. Two different phantom types, namely, (1) ordinary slab and (2) MIRD anthropomorphic phantoms, were used. We have found that the generated 13N peak in such highly inhomogeneous targets (ordinary slab and human phantom) is close to the actual Bragg peak, when irradiated by incident proton beam. The feasibility of using the SA technique to estimate the distribution of positron emitter was also investigated. The current findings and the developed tools in the present work would be helpful in proton range monitoring and verification in realistic clinical radiation therapy using proton beams.

Proton range monitoring using 13N peak for proton therapy applications.

The Monte Carlo method is employed in this study to simulate the proton irradiation of a water-gel phantom. Positron-emitting radionuclides such as 11C, 15O, and 13N are scored using the Particle and Heavy Ion Transport Code System Monte Carlo code package. Previously, it was reported that as a result of 16O(p,2p2n)13N nuclear reaction, whose threshold energy is relatively low (5.660 MeV), a 13N peak is formed near the actual Bragg peak. Considering the generated 13N peak, we obtain offset distance values between the 13N peak and the actual Bragg peak for various incident proton energies ranging from 45 to 250 MeV, with an energy interval of 5 MeV. The offset distances fluctuate between 1.0 and 2.0 mm. For example, the offset distances between the 13N peak and the Bragg peak are 2.0, 2.0, and 1.0 mm for incident proton energies of 80, 160, and 240 MeV, respectively. These slight fluctuations for different incident proton energies are due to the relatively stable energy-dependent cross-section data for the 16O(p,2p2n)13N nuclear reaction. Hence, we develop an open-source computer program that performs linear and non-linear interpolations of offset distance data against the incident proton energy, which further reduces the energy interval from 5 to 0.1 MeV. In addition, we perform spectral analysis to reconstruct the 13N Bragg peak, and the results are consistent with those predicted from Monte Carlo computations. Hence, the results are used to generate three-dimensional scatter plots of the 13N radionuclide distribution in the modeled phantom. The obtained results and the developed methodologies will facilitate future investigations into proton range monitoring for therapeutic applications.

Renal statistical map for positron emission tomography with [O-15] water.

Image statistics are frequently used for functional and molecular imaging research in which images from a patient group with a specific diagnosis are compared with images from a healthy control group who have been matched for demographic variables. The success of image statistics for brain imaging has encouraged us to develop a method for obtaining volumetrically normalized kidney to perform image statistics so that we can locally visualize the statistical significant difference comparing voxel by voxel between certain groups in terms kidney blood flow kinetic parameters. For the development of this evolutionary process, we first volumetrically normalized all subjects, which include healthy control (HC) and chronic renal failure (CRF) patients, 15O water PET image with respect to one HC subject's MRI image using affine transformation. Then 15O kinetic parametric images of normalized kidneys were obtained through the basis function method. Finally, the statistical map of these parametric images was produced using the threshold-free cluster enhancement based permutation method. Kinetic parameters of kidney namely, uptake rate constant (K1), clearance rate constant (k2) and blood volume (Va), were found to be notably lower in CRF than those of in HC and k2 parameter was found to be more stable compared to K1 and Va. The statistical map of these parametric images allowed us to visualize local significant differences statistically (P<0.05) between HC and CRF groups. Though PET and MRI techniques have enormous potentiality for functional and molecular imaging of kidney, these are, at best, in experimental level. It is speculated that statistical mapping of kidney could play a significant role in the successful implementation of functional and molecular kidney imaging. However, more research involving a larger sample size and improved normalization technique will be needed for the robustness of the process.

Level and determinants of birth preparedness and complication readiness among pregnant women: A cross sectional study in a rural area in Bangladesh.

BACKGROUND: Increasing the level of birth preparedness and complication readiness (BP/CR) is one of the key interventions to promote optimal utilization of skilled maternal health services. It is therefore essential to determine the women's ability to recognize the danger signs and the level of BP/CR. This information can be used to design more effective health interventions. OBJECTIVES: This study was conducted to determine the knowledge in recognition of maternal complications, and the level and factors associated with BP/CR in rural Matlab, Bangladesh. METHODS: A community-based cross-sectional survey was conducted from June- October 2015 on a randomly selected 2262 women who delivered live or stillbirth during the year 2014. A pretested and structured questionnaire was used for data collection. Descriptive and analytical statistical methods were used. RESULTS: The proportion of study participants with "good knowledge", measured by the ability to recognise three or more danger signs, in pregnancy and delivery were 26% and 23%, respectively. Out of four BP/CR components, about 15% women saved money, 12% women identified facility for delivery, 9.6% women planned to deliver by skilled birth attendant and 5.3% of women arranged transport. About 12% of women were "well prepared", measured by planning of at least two components, for skilled childbirth and emergency obstetric complications. In the multivariable logistic regression analysis, asset index, antenatal care (ANC) visits and knowledge of danger signs during pregnancy and delivery were associated with BP/CR. The adjusted odds ratio (OR) of "well prepared" was 4.09 (95% confidence interval [CI]: 2.45-6.82) among women with an asset index of five (richest), compared with women in the asset index of one (poorest). The odds of "well prepared" was six times (OR 5.98, 95% CI: 3.85-9.28) higher for women with four or more ANC visits, compared to women with none or one ANC visit. In comparison to women with "poor knowledge" on maternal danger signs during pregnancy and delivery, the odds ratio of "well prepared" among women with good knowledge during pregnancy and in delivery were 1.95 (95% CI: 1.44-2.63) and 1.74 (95% CI: 1.28-2.36), respectively. CONCLUSION: The study revealed a low level of maternal knowledge of danger signs and BP/CR among pregnant women. Further, low socioeconomic status, fewer ANC visits and poor knowledge in recognition of dangers signs on maternal health were associated with low BP/CR. More emphasis should be placed on the quality of information offered to the pregnant women during the prenatal contact and women from low socio-economic gradient should be prioritized to optimize the impact of future BP/CR interventions.

Who enrols in voluntary micro health insurance schemes in low-resource settings? Experience from a rural area in Bangladesh.

BACKGROUND: Micro health insurance (MHI) has proved to be a potential health-financing tool for many developing countries. Bangladesh also included MHI in its current health-financing strategy which aims to achieve universal health coverage. However, low uptake, low renewal and high dropouts have historically challenged financial sustainability of these schemes. OBJECTIVE: This study aims to identify factors influencing people from low-resource settings, particularly those from Bangladesh, to enrol in MHI schemes. METHODS: The study analyses the 'Amader Shasthya' MHI scheme operating in Chakaria, a sub-district under Cox's Bazar district, Bangladesh. A household survey was carried out during May-June 2016 among 2,000 households from the scheme coverage area. The Outreville's insurance-demand framework was used to identify enrolment influencing factors. Multivariate logistic regression analysis was carried out to identify significant influencing factors of enrolment. RESULTS: Enrolment influencing factors were identified in four dimensions: economic, socio-cultural, demographic and structural. Households with the main income earner having 10+ years of schooling (odds 1.9 [CI 1.2-2.9] compared to illiterate), having financial literacy (odds 1.5 [CI 1.2-1.8] compared to financially illiterate) and being a public/private service holder (odds 1.6 [CI 1.1-2.4] compared to menial labour) were more likely to enrol. Membership in development programmes of NGOs also influenced enrolment decision significantly (odds 1.3 [CI 1.0-1.5]). The presence of chronic illness in household encouraged enrolment (odds 1.5 [CI 1.2-1.8]). Households living closer to health centres were more likely to enrol (odds 2.1 [CI 1.6-2.7]) compared to those living further away. CONCLUSION: The findings are expected to have significant implications in terms of designing similar health insurance schemes, particularly in terms of designing demand-driven and context adapted schemes that have greater potential to attract a larger client pool, ensure effective risk pooling and eventually expedite the achievement of universal health coverage in low-resource settings.

Online molecular image repository and analysis system: A multicenter collaborative open-source infrastructure for molecular imaging research and application.

Molecular imaging serves as an important tool for researchers and clinicians to visualize and investigate complex biochemical phenomena using specialized instruments; these instruments are either used individually or in combination with targeted imaging agents to obtain images related to specific diseases with high sensitivity, specificity, and signal-to-noise ratios. However, molecular imaging, which is a multidisciplinary research field, faces several challenges, including the integration of imaging informatics with bioinformatics and medical informatics, requirement of reliable and robust image analysis algorithms, effective quality control of imaging facilities, and those related to individualized disease mapping, data sharing, software architecture, and knowledge management. As a cost-effective and open-source approach to address these challenges related to molecular imaging, we develop a flexible, transparent, and secure infrastructure, named MIRA, which stands for Molecular Imaging Repository and Analysis, primarily using the Python programming language, and a MySQL relational database system deployed on a Linux server. MIRA is designed with a centralized image archiving infrastructure and information database so that a multicenter collaborative informatics platform can be built. The capability of dealing with metadata, image file format normalization, and storing and viewing different types of documents and multimedia files make MIRA considerably flexible. With features like logging, auditing, commenting, sharing, and searching, MIRA is useful as an Electronic Laboratory Notebook for effective knowledge management. In addition, the centralized approach for MIRA facilitates on-the-fly access to all its features remotely through any web browser. Furthermore, the open-source approach provides the opportunity for sustainable continued development. MIRA offers an infrastructure that can be used as cross-boundary collaborative MI research platform for the rapid achievement in cancer diagnosis and therapeutics.

Post-harvest loss of farm raised Indian and Chinese major carps in the distribution channel from Mymensingh to Rangpur of Bangladesh.

Post-harvest loss of catla (Catla catla), rohu (Labeo rohita), mrigal (Cirrhinus mrigala), silver carp (Hypophthalmichthys molitrix), grass carp (Ctenopharyngodon idella) and sarpunti (Puntius sarana) in a single distribution chain from harvest in Mymensingh to retail sale Rangpur town were determined, in order to obtain information on quality deterioration and existing handling and icing conditions so that suggestions for improving such practices can be made. Quality defect points of the fish at different steps of distribution channels were determined using a sensory based quality assessment tool. Percent quality loss of fish at each step of distribution was calculated from the number of cases that crossed sensory quality cut-off points. Neither of the fish lost their quality when they were in the farm gate, during transportation and in wholesale markets in Rangpur but most of the fishes lost their quality at the retail fish shops. The quality loss was 8, 12, 8, 6, 10 and 14% in case of C. catla, C. mrigala, L. rohita, H. molitrix, C. idella and P. sarana respectively in the retail markets. Fishes were not properly handled, bamboo baskets wrapped with polythene sheet were used as carrying container and inadequate ice was used during transportation. Retailers were found to be more proactive in the use of ice. However, most of the fishes were deteriorated during retail sale. The losses of farmed fishes could be minimized by adopting good handling practices like using insulated container and adequate icing.