Top-Gated Chemical Vapor Deposited Mos2 Field-Effect Transistors On Si3N4 Substrates

We report the electrical characteristics of chemical vapor deposited (CVD) monolayer molybdenum disulfide (MoS2) top-gated field-effect transistors (FETs) on silicon nitride (Si3N4) substrates. We show that Si3N4 substrates offer comparable electrical performance to thermally grown SiO2 substrates for MoS2 FETs, offering an attractive passivating substrate for transition-metal dichalcogenides (TMD) with a smooth surface morphology. Single-crystal MoS2 grains are grown via vapor transport process using solid precursors directly on low pressure CVD Si3N4, eliminating the need for transfer processes which degrade electrical performance. Monolayer top-gated MoS2 FETs with Al2O3 gate dielectric on Si3N4 achieve a room temperature mobility of 24 cm(2)/V s with I-on/I-off current ratios exceeding 10(7). Using HfO2 as a gate dielectric, monolayer top-gated CVD MoS2 FETs on Si3N4 achieve current densities of 55 mu A/mu m and a transconductance of 6.12 mu S/mu m at V-tg of -5V and V-ds of 2V. We observe an increase in mobility at lower temperatures, indicating phonon scattering may dominate over charged impurity scattering in our devices. Our results show that Si3N4 is an attractive alternative to thermally grown SiO2 substrate for TMD FETs. (C) 2015 AIP Publishing LLC.STTR programNSF NASCENT ERCArmy Research Office under STTR W911NF-14-P-0030Microelectronics Research Cente

DEVELOPMENT OF A DENSITOMETRIC HIGH-PERFORMANCE THIN-LAYER CHROMATOGRAPHIC METHOD FOR THE QUANTITATIVE ANALYSIS OF URSOLIC ACID IN THE LEAVES OF SPECIES OF GENUS TECOMA AND TABEBUIA OF BIGNONIACEAE FAMILY

Objective: A simple and sensitive high-performance thin–layer chromatographic (HPTLC) method was developed for the quantification of ursolic acid in the leaves of three species of genus Tecoma (Tecoma gaudichaudi DC, Tecoma capensis (Thunb.) Lindl, Tecoma stans (L.) Juss. ex Kunth) and genus Tabebuia (Tabebuia rosea Bertol) belong to family Bignoniaceae.Methods: Chromatography was performed on Silica gel 60 F254 precoated HPTLC Plates with optimised mobile phase pet ether: ethyl acetate: formic acid (7:3:0.5, v/v/v). The plate was derivatized with p-anisaldehyde reagent and scanned at 540 nm. The developed method was found to give a compact spot for ursolic acid at Rf value 0.43±0.01. The method was validated using International Council for Harmonization (ICH) guidelines, including linearity, precision, accuracy, and robustness.Results: Ursolic acid was found to be present in four species, i.e., Tecoma gaudichaudi DC (1.48%w/w), Tecoma capensis (Thunb.) Lindl. (0.79%w/w), Tecoma stans (L.) Juss. Ex Kunth (1.11%w/w), Tabebuia rosea (Bertol.) (1.13%w/w). A good linearity relationship was found to be (200-1400ng band−1) with a correlation coefficient (r2) value of 0.9946 with ursolic acid. Limit of detection and limit of quantification was considered to be 40.66, 123.21 ng per band respectively. The developed method was found to be accurate and precise with 1.32%, 1.19% (%RSD) for interday and intraday precision. The accuracy of the method was performed by recovery studies at three different concentration levels, and the average percentage recovery was found to be 98.05% for ursolic acid.Conclusion: The proposed method for the quantitation of ursolic acid was found to be reproducible and simple

Identifying Implementation Bugs in Machine Learning based Image Classifiers using Metamorphic Testing

We have recently witnessed tremendous success of Machine Learning (ML) in practical applications. Computer vision, speech recognition and language translation have all seen a near human level performance. We expect, in the near future, most business applications will have some form of ML. However, testing such applications is extremely challenging and would be very expensive if we follow today's methodologies. In this work, we present an articulation of the challenges in testing ML based applications. We then present our solution approach, based on the concept of Metamorphic Testing, which aims to identify implementation bugs in ML based image classifiers. We have developed metamorphic relations for an application based on Support Vector Machine and a Deep Learning based application. Empirical validation showed that our approach was able to catch 71% of the implementation bugs in the ML applications.Comment: Published at 27th ACM SIGSOFT International Symposium on Software Testing and Analysis (ISSTA 2018

Free Vibration Analysis of Functionally Graded Beams

Free vibration analysis of functionally graded beams is carried out for various classical boundary conditions. Two separate finite element formulations, one based on Euler-Bernoulli beam theory and other based on Timoshenko beam theory are developed. Principle of virtual work is used to obtain the finite element system of equations. Numerical results are provided to demonstrate the effect of transverse shear on the natural frequencies and mode shapes for different length-to-thickness ratios and volume fraction exponents of functionally graded material (FGM) beams for the boundary conditions considered. It was observed that transverse shear significantly affects the fundamental frequency and mode shape for lower length to thickness ratios of FGM beams. Further, the effect was observed to be more prominent at higher modes for all the volume fraction exponents of FGM beam.Defence Science Journal, 2012, 62(3), pp.139-146, DOI:http://dx.doi.org/10.14429/dsj.62.132

Thermal Buckling and Free Vibration Analysis of Heated Functionally Graded Material Beams

The effect of temperature dependency of material properties on thermal buckling and free vibration of functionally graded material (FGM) beams is studied. The FGM beam is assumed to be at a uniform through thickness temperature, above the ambient temperature. Finite element system of equations based on the first order shear deformation theory is developed. FGM beam with axially immovable ends having the classical boundary conditions is analysed. An exhaustive set of numerical results, in terms of buckling temperatures and frequencies, is presented, considering the temperature independent and temperature dependent material properties. The buckling temperature and fundamental frequency obtained using the temperature independent material properties is higher than that obtained by using the temperature dependent material properties, for all the material distributions, geometrical parameters in terms of length to thickness ratios and the boundary conditions considered. It is also observed that the frequencies of the FGM beam will reduce with the increase in temperature. This observation is applicable for the higher modes of vibration also. The necessity of considering the temperature dependency of material properties in determining thermal buckling and vibration characteristics of FGM beams is clearly demonstrated.Defence Science Journal, 2013, 63(3), pp.315-322, DOI:http://dx.doi.org/10.14429/dsj.63.237

Genetic variability in sugarcane (Saccharum spp. hybrid) genotypes through inter simple sequence repeats (ISSR) markers

In the present study, 14 sugarcane (Saccharum spp. hybrid) genotypes were used for genomic diversity analysis based on nineteen inter simple sequence repeat (ISSR). These nineteen sets of ISSR markers generated a total of 164 discernible and reproducible bands including 109 polymorphic and 55 monomorphic bands. The unweighted pair group method with arithmetic average (UPGMA) analysis revealed three distinct clusters: I, II and III within the 14 genotypes. The polymorphic information content (PIC) value per locus ranged from 0.14 (UBC811) to 0.53 (ISSR1) locus with an average of 0.42 for all loci. The range of genetic distance or coefficient of similarity among sugarcane genotypes varied 0.14 - 0.78. The analysis of these similarities matrix revealed that greater similarity between CoS03234 and CoSe1424 (0.78), and lowest similarity between CoS03234 and Co0118 (0.14). The knowledge gained in this study would be useful to future breeding programs for increasing genetic diversity of sugarcane varieties and cultivars to meet the increasing demand of sugarcane cultivation for sugar and bio energy uses

Effect of integration of supplemental nutrition with public health programmes in pregnancy and early childhood on cardiovascular risk in rural Indian adolescents: long term follow-up of Hyderabad nutrition trial.

OBJECTIVE: To determine whether integration of nutritional supplementation with other public health programmes in early life reduces the risk of cardiovascular disease in undernourished populations. DESIGN: Approximately 15 years' follow-up of participants born within an earlier controlled, community trial of nutritional supplementation integrated with other public health programmes. SETTING: 29 villages (15 intervention, 14 control) near Hyderabad city, south India. PARTICIPANTS: 1165 adolescents aged 13-18 years. INTERVENTION: Balanced protein-calorie supplementation (2.51 MJ, 20 g protein) offered daily to pregnant women and preschool children aged under 6 years, coupled with integrated delivery of vertical public health programmes. MAIN OUTCOME MEASURES: Height, adiposity, blood pressures, lipids, insulin resistance (homoeostasis model assessment (HOMA) score), and arterial stiffness (augmentation index). RESULTS: The participants from the intervention villages were 14 mm (95% confidence interval 4 to 23; P=0.007) taller than controls but had similar body composition. The participants from the intervention villages had more favourable measures of insulin resistance and arterial stiffness: 20% (3% to 39%; P=0.02) lower HOMA score and 3.3% (1% to 5.7%; P=0.008) lower augmentation index. No strong evidence existed for differences in blood pressures and serum lipids. CONCLUSIONS: In this undernourished population, integrated delivery of supplemental nutrition with other public health programmes in pregnancy and early childhood was associated with a more favourable profile of cardiovascular disease risk factors in adolescence. This pragmatic study provides the most robust evidence to date on this important hypothesis for which classic trials are unlikely. Improved maternal and child nutrition may have a role in reducing the burden of cardiovascular disease in low income and middle income countries

Nanocrystalline Pentaerythritoltetranitrate using Sol-Gel Process

The secondary explosives developed with reduced particle size tend to be more insensitive for mechanical stimuli and may release energy with faster rate and gaining more importance nowadays. Therefore, aiming to reduce the particle size of one of the popular explosives, viz., pentaerythritoltetranitrate (PETN) to the nanometer range, a method for preparation of nanocrystalline PETN in the silica (SiO2) gel matrix using sol-gel process has been demonstrated. The PETN-SiO2 xerogels were prepared containing PETN content ranging from 50 per cent to 90 per cent (w/w) and the xerogels were characterised using different techniques. An exothermic peak at around 185 oC preceded by an endotherm in thermal analysis accompanied with weight loss in the temperature range from 150 oC to 200 oC   for the xerogel confirmed the presence of PETN in xerogel. Infrared spectra of xerogels showed peaks at around 1285 cm-1 and 1700 cm-1 assigned to O-NO2 and C-O bond representing PETN. Small angle x-ray scattering measurements on xerogels indicated that PETN entered in the pores of silica matrix. Transmission electron microscopy revealed that cystalline PETN    with particle size of around 15 nm dispersed in silica xerogel. The specific surface area for the PETN-SiO2 (90:10) xerogels was found to be 75 m2/g.Defence Science Journal, 2011, 61(6), pp.534-539, DOI:http://dx.doi.org/10.14429/dsj.61.59

Brief Report: A Phase II Study of Sunitinib in Malignant Pleural Mesothelioma. The NCIC Clinical Trials Group

IntroductionMalignant pleural mesothelioma (MPM) is an aggressive malignancy that most often presents at an advanced, incurable stage. After the failure of standard first-line cisplatin/antifolate chemotherapy, there is no accepted treatment. The vascular endothelial growth factor pathway may be a relevant therapeutic target in MPM.MethodsThis open-labeled phase II trial evaluated single-agent sunitinib, an inhibitor of multiple receptor tyrosine kinases including the vascular endothelial growth factor receptors, given at 50 mg daily orally for 4 weeks followed by a 2-week rest, in patients with advanced MPM. Two cohorts were studied: cohort 1, in which patients had previously received cisplatin-based chemotherapy, and cohort 2, consisting of previously untreated patients. A two-stage design was used for both cohorts; the primary outcome was objective response rate as determined by the RECIST criteria modified for MPM. Secondary outcomes included rates and duration of disease control, progression-free survival and overall survival, and safety and tolerability.ResultsA total of 35 eligible patients were enrolled (17 to cohort 1 and 18 to cohort 2). Neither cohort met the criteria for continuing to the second stage of accrual; only one objective response, confirmed by independent review, was observed in a previously untreated patient. Median progression-free and overall survivals were 2.8 and 8.3 months in cohort 1, and 2.7 and 6.7 months in cohort 2, respectively. Observed toxicity was within that expected for sunitinib.ConclusionsSunitinib, similar to other angiogenesis inhibitors, has limited activity in MPM. Future trials of angiogenesis inhibitors given as single agents in unselected patients with MPM are not warranted