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Light-sheet based lithography technique for patterning an array of microfluidic channels
No full textWe propose a Light-sheet laser interference lithography technique for fabricating periodic microfluidic channels. This technique uses multiple light-sheet illumination pattern that is generated using a spatial filter at the back-aperture of the cylindrical lens. Specially designed spatial filter is used that give rise to a periodic pattern at the focal plane which is essentially a 1D Fourier transform of the spatial filter transfer function. One-dimensional focusing property of the cylindrical lens result in the generation of line shaped channel geometry. To design microfluidic channels, the illumination pattern is exposed to the glass substrate coated with a photopolymer sensitized to 532 nm and subsequently developed using standard chemical protocols. Experimentally, the 1D periodic channel structure has an approximate width and periodicity of approximately 11.25 microns. Light-sheets based lithography technique offer a fast and single-shot process to generate microfluidic channels
Deep and Shallow convections in Atmosphere Models on Intel (R) Xeon Phi (TM) Coprocessor Systems
No full textDeep and shallow convection calculations occupy significant times in atmosphere models. These calculations also present significant load imbalances due to varying cloud covers over different regions of the grid. In this work, we accelerate these calculations on Intel (R) Xeon Phi (TM) Coprocessor Systems. By employing dynamic scheduling in OpenMP, we demonstrate large reductions in load imbalance and about 10% increase in speedups. By careful categorization of data as private, firstprivate and shared, we minimize data copying overheads for the coprocessors. We identify regions of false sharing among threads and eliminate them by loop rearrangements. We also employ proportional partitioning of independent column computations across both the CPU and coprocessor cores based on the performance ratio of the computations on the heterogeneous resources. These techniques along with various vectorization strategies resulted in about 30% improvement in convection calculations
Temperature dependent electrical properties of AlN/Si heterojunction
No full textAlN is an integral part of many Si based electronic, optoelectronic, and electromechanical devices. The transport of charge carriers and their recombination at the AlN (0002)/Si (111) interface become crucial for the performance and reliability of such devices. In this work, we have studied the temperature dependent current-voltage (I-V-T) characteristics of AlN/Si heterojunctions to gain a deeper understanding. The analysis of the I-V-T characteristics interestingly suggested a temperature dependent turn-on voltage in the forward bias of the Schottky barrier. Also, the Schottky barrier itself was found to be temperature dependent as expected. We have qualitatively explained the temperature dependence of the turn-on voltage in terms of trap states at the AlN/Si heterojunction. Published by AIP Publishing
Task context determines whether common or separate inhibitory signals underlie the control of eye-hand movements
No full textWhereas inhibitory control of single effector movements has been widely studied, the control of coordinated eye-band movements has received less attention. Nevertheless, previous studies have contradictorily suggested that either a common or separate signal/s is/are responsible for inhibition of coordinated eye-hand movements. In continuation of our previous study. we varied behavioral contexts and used a stochastic accumulation-to-threshold model, which predicts a scaling of the mean reaction time distribution with its variance, to study the inhibitory control of eye-hand movements. Participants performed eye-hand movements in different task conditions, and in each condition they had to redirect movements in a fraction of trials. Task contexts where the behavior could be best explained by a common initiation signal had similar error responses for eye and hand, despite having different mean reaction times, indicating a common inhibitory signal. In contrast, behavior that could be best explained by separate initiation signals had dissimilar error responses for eye and hand indicating separate inhibitory signals. These behavioral responses were further validated using electromyography and computational models having either a common or separate inhibitory control signal/s. Interestingly, in a particular context, whereas in majority trials a common initiation and inhibitory signal could explain the behavior, in a subset of trials separate initiation and inhibitory signals predicted the behavior better. This highlights the flexibility that exists in the brain and in effect reconciles the heterogeneous results reported by previous studies. NEW & NOTEWORTHY Prior studies have contradictorily suggested either a single or separate inhibitory signal/s underlying inhibition of coordinated eye-hand movements. With the use of different tasks, we observed that when eye-hand movements were initiated by a common signal, they were controlled by a common inhibitory signal. However, when the two effectors were initialed by separate signals, they were controlled by separate inhibitory signals. This highlights the flexible control of eye-hand movements and reconciles the heterogeneous results previously reported in the literature
Influence of hot rolling on microstructure and mechanical behaviour of A16061-ZrB2 in-situ metal matrix composites
No full textSynthesis of aluminium based metal matrix composites by in-situ reaction is considered as an alternative method for production of high quality metal matrix composites. In-situ technique eliminates the limitations associated with ex-situ processing technique and it is one of the most widely accepted one. In the present work, Al6061ZrB(2)in-situ composites have been developed by stir casting technique using commercially available Al-10%Zr and Al-3%B master alloys. Cast matrix alloy and developed in-situ composites were hot rolled at a temperature of 400 degrees C. Both as-cast and hot rolled matrix alloy and its in-situ composites were subjected to microstructure analysis, microhardness test, grain size studies and tensile test. Tensile behaviour of hot rolled alloy and its insitu composites were evaluated in the rolling direction (RD), 45 degrees from rolling direction (45D) and transverse direction (TD) and compared with cast ones. Optical and SEM micrographs of hot rolled in-situ composites show that the ZrB2 particles are aligned in the rolling direction. Both as-cast and hot rolled in-situ composites have displayed extensive grain refinement and enhanced mechanical properties when compared with unreinforced alloy. However, ductility of the in-situ composites decreases with increase in ZrB2 content. Hot rolled alloy and its in-situ composites exhibited remarkable improvement in ultimate tensile strength and ductility at 45 degrees from rolling direction compared to transverse and rolling directions
Enhanced storage ability by using a porous pyrrhotite@N-doped carbon yolk-shell structure as an advanced anode material for sodium-ion batteries
No full textSodium-ion batteries (SIBs) are undoubtedly the most promising alternatives to lithium-ion batteries considering the natural abundance, distribution and cost of sodium resources. Still, SIBs face challenges in the development of suitable anode materials due to the large volume change during sodiation/de-sodiation, which results in inferior cycling stability. Herein, we synthesized a yolk-shell structured pyrrhotite (Fe1-xS)@N-doped carbon (FS@NC) through a solution-based method and investigated its electrochemical properties for use in SIBs as an anode material. The optimized yolk-shell structured FS@NC with distinctive voids and a core exhibited a high reversible capacity of 594 mA h g(-1) over 100 cycles at 100 mA g(-1), excellent rate capability and superior cycling performance compared to core-shell and pristine Fe1-xS materials. During the charge and discharge cycles, the synergistic effect of the porous core (Fe1-xS) with empty voids and a defective carbon shell configuration provided a large electrode/electrolyte contact area and shortened the diffusion path for electrons and sodium ions. It also mitigated the structural degradation by accommodating the volume change during continuous cycles, which was confirmed by ex situ SEM and TEM analyses. To demonstrate a practical application, we assembled a sodium-ion full cell with an O3-type NaCo0.5Fe0.5O2 cathode and a yolk-shell structured FS@NC anode, and the results showed superior energy storage performance
Bloom of the diatom, Biddulphia sp and ecology of Pulicat lagoon, Southeast India in the aftermath of the 2015 north east monsoonal rainfall
No full textPulicat lagoon in the south-east coast of India is recharged with the highest fresh water influx annually during north-east winter monsoon. An abrupt heavy rainfall in November-December 2015 was a flood calamity in the region that inundated the lagoon. We investigated the physico-chemical characteristics and palynological profile of the surface sediments from the lagoon at water depth between 0.5 and 2m to understand the impact of the 2015 event. On the basis of a marine index', three zones were demarcated, the LC zone' (Araniar river-lagoon confluence, south), the LM zone' and the LL zone' (Kalangi river confluence, north) showing values of 4.55, 1.25 and 0.25, respectively, indicating the extent of tidal influence. The dissolved oxygen, pH and salinity ranged between 6.4 and 9.6mg/L, 7.96-9.23 and average 12.3ppt at different sites, respectively. The highest salinity (31 and 31.8ppt) was in the LC zone along with the highest dissolved inorganic nitrogen (DIN) concentrations (275-288mmol/m(3)) too. The dissolved inorganic phosphates (DIP) ranged between 8.5 and 29.5mmol/m(3), which was relatively high. Sandy sediment, high sodium (Na+) and chloride (Cl-) ions too indicate the landward extension of seawater influx. Forsterite (Mg2SiO4) and beta-uranophane (Ca(UO2)SiO3(OH)](2).(H2O) minerals show higher values with the dominance of olivine (MgFe)(2)SiO4) and quartz (SiO2) in this zone indicating magnitude of fresh water influx too through Araniar river. The highest calcium, magnesium and potassium ions were also observed in LC zone. Fe-rich goethite, calcite and aragonite were recorded at all sites but with dominance of illite in LL zone. Halite, an evaporite recorded from all sites shows inundation of the entire lagoon during flooding event. Results show a bloom of Biddulphia pulchella, B. biddulphiana and B. laevis in association with Cladophora in LC zone which serves as potential indicators of physico-chemical characteristics of the lagoon showing intense response to catastrophic events of floods due to above normal monsoon variability
Dependence structure of urban precipitation extremes
No full textAddressing spatial variation of extreme precipitation in urban areas is important for urban hydrologic designs. Climatology of urban areas is, in general, different from that of its surroundings and the spatial variation of extreme precipitation within the city exhibits shorter spatial range, especially for short duration events. This work aims at understanding the dependence structure of extreme precipitation within an urban area and its surrounding non-urban areas at various durations. The spatial dependence of precipitation is analysed with three different measures for examining dependence, considering observations from pairs of stations. Further, the spatial precipitation extremes are modelled with the max-stable process to include the dependence structure of spatial extremes. The City of Berlin, Germany, with surrounding non-urban area is considered to demonstrate the methodology. For this case study, the hourly precipitation shows weaker dependence within the city even at small distances, whereas the daily precipitation shows a high degree of dependence. This dependence structure of the daily precipitation gets masked as more and more surrounding non-urban areas are included in the analysis. Further, the extreme precipitation at different durations are modelled considering max-stable process. Different geographical and climatological covariates are considered in the modelling of location and scale parameters of the Generalized Extreme Value distribution. The geographical covariates are seen to be predominant within the city and the climatological covariates prevail when non-urban areas are added. These results suggest the importance of quantification of dependence structure of spatial precipitation at the sub-daily timescales, as well as the need to more precisely model spatial extremes within the urban areas
Reduced graphene oxide-based broad band photodetector and temperature sensor: effect of gas adsorption on optoelectrical properties
No full textReduced graphene oxide (rGO) has found tremendous application due to its versatile and tunable properties. We have prepared rGO by the green hydrothermal method without using any toxic additives that comprise 5-14 layers with an average interlayer distance of 3.5 angstrom. A device with Ag-rGO-Ag configuration has been fabricated that exhibits excellent stable and reproducible photoresponse properties ranging from UV-VIS (ultraviolet-visible) to the near IR (infrared) region. Responsivity and external quantum efficiency (EQE) values are as high as 0.71, 0.733, 0.230, and 0.313AW(-1) and 57, 85, 88, and 120% using 1550, 1064, 632, and 325nm wavelength, respectively. We have shown that the temperature-dependent resistance follows a well-definite exponential behavior which indicates potential application of rGO as temperature sensor. Overall, these results suggest that rGO can be a potential material for low-cost, environment-friendly, and efficient broadband photodetector and temperature sensor. Also, pressure-dependent optoelectrical measurements have been carried out that reveal adsorption characteristics of various gases
