Interferometric lithography for nanoscale feature patterning: a comparative analysis between laser interference, evanescent wave interference, and surface plasmon interference

In this paper, we experimentally demonstrate and compare single-exposure multiple-beam interference lithography based on conventional laser interference, evanescent wave interference, and surface plasmon interference. The proposed two-beam and four-beam interference approaches are carried out theoretically and verified experimentally, employing the proposed configurations so as to realize the patterning of one- and two-dimensional periodic features on photoresists. A custom-fabricated grating is employed in the configuration in order to achieve two- and four-beam interference.     

A Bandwidth Efficient Turbo Coding Scheme for VDSL Systems

The current forward error correction (FEC) scheme for very high bit-rate digital subscriber line (VDSL) systems in the ANSI standard employs a 16-state four-dimensional (4D) Wei code as the inner code and the Reed-Solomon (RS) code as the outer code. The major drawback of this scheme is that further improvement cannot be achieved without a substantial increase in the complexity and power penalty. Also, a VDSL system employing the 4D Wei-RS scheme operates far below the channel capacity. In 1993, powerful turbo codes were introduced whose performance closely approaches the Shannon limit. In this paper, we propose a bandwidth and power efficient turbo coding scheme for VDSL modems in order to obtain high data rates, extended loop reach and increased transmission robustness. We also propose a pipelined decoding scheme to reduce the latency at the receiver end. The objective of the proposed scheme is to provide a higher coding gain than that given by the 4D Wei-RS scheme, resulting in an improved performance of the VDSL modems in terms of bit rate, loop length and transmitting power. The scheme is investigated for various values of transmitting power, signaling frequencies and numbers of crosstalkers for a targeted bit error rate of 10⁻⁵ and is implemented in a system with a quadrature amplitude modulation in which a mixed set partitioning mapping is employed to reduce the decoding complexity. The effects of code complexity, interleaver length, the number of decoding iterations and the level of modulation on the performance of VDSL modems are explored. Simulation results are presented and compared to those of the 4D Wei-RS scheme. The results show that the choice of turbo codes not only provides a significant coding gain over the standard FEC scheme but also efficiently maximizes the loop length and bit rate at a very low transmitting power in the presence of dominant far-end crosstalk and intersymbol interference. In order to compare the hardware complexity, we synthesize the proposed and 4D Wei-RS schemes using SYNOPSYS with the target technology of Xilinx 4020e-3. The Xilinx field programmable gate array statistics of the proposed scheme is compared with that of the 4D Wei-RS scheme.     

Modeling the viral load dependence of residence times of virus-laden droplets from COVID-19-infected subjects in indoor environments

In the ongoing COVID-19 pandemic situation, exposure assessment and control strategies for aerosol transmission path are feebly understood. A recent study pointed out that Poissonian fluctuations in viral loading of airborne droplets significantly modifies the size spectrum of the virus-laden droplets (termed as “virusol”) (Anand and Mayya, 2020). Herein we develop the theory of residence time of the virusols, as contrasted with complete droplet system in indoor air using a comprehensive “Falling-to-Mixing-Plate-out” model that considers all the important processes namely, indoor dispersion of the emitted puff, droplet evaporation, gravitational settling, and plate out mechanisms at indoor surfaces. This model fills the existing gap between Wells falling drop model (Wells, 1934) and the stirred chamber models (Lai and Nazarofff, 2000). The analytical solutions are obtained for both 1-D and 3-D problems for non-evaporating falling droplets, used mainly for benchmarking the numerical formulation. The effect of various parameters is examined in detail. Significantly, the mean residence time of virusols is found to increase nonlinearly with the viral load in the ejecta, ranging from about 100 to 150 s at low viral loads (<10⁴/ml) to about 1100–1250 s at high viral loads (>10¹¹/ml). The implications are discussed.     

Effect of reaction time and PVP contents on morphologies of hierarchical 3D flower-like ZnCo2O4 microstructures for energy storage devices

Hierarchical 3D flower-like ZnCo₂O₄ (ZCO) microstructures assembled from petal-like nanosheets/flakes of non-uniform sizes were engineered by a polyvinylpyrrolidone (PVP)-assisted hydrothermal method. Four different samples/morphologies of ZCO were obtained (PVP-L@6, PVP-H@6, PVP-L@12, and PVP-H@12) by altering the reaction parameters such as surfactant concentration (PVP) and reaction time, which can play a significant role in the formation of flower-/petal-/flake-like architectures. The alteration of the reaction parameters not only resulted in morphological changes but also affected the surface area, pore size/volume, crystalline nature, non-stoichiometry of Zn, Co, and O in ZCO, and their electrochemical performance. The metal (Zn/Co)/O deficiencies of ZCO samples were investigated via X-ray photoelectron spectroscopy and supported by the Rietveld refinement method. Furthermore, a plausible growth mechanism for these flower-like ZCO microstructures was projected based on the experimental results. The four dissimilar samples/morphologies of ZCO, which exhibit different electrochemical performances, were investigated. Our results show that PVP-H@12 exhibits higher specific capacitance (761/680 F g⁻¹ at 0.35/1 A g⁻¹) and good cycling constancy (90% capacitive retention after 2000 cycles at 5 Ag⁻¹) among all the four samples.     

An Improved Process for Selective Liquid-Phase Air Oxidation of Toluene

An improved process for the oxidation of toluene to obtain benzaldehyde and benzyl alcohol with high selectivities using a Co/Mn/Br^– composite catalytic system in liquid phase is described. A protocol for recovery and reuse of the composite catalyst is developed. The use of low concentrations of composite catalytic systems aimed at minimizing corrosion of the reaction, and higher concentrations of toluene affording higher productivity and recyclability of the catalyst giving high turnover number, are the remarkable achievements of the present methodology. Investigation into the recycle, aging and spectroscopic studies of the catalytic system improves the understanding of the process, chemistry and mechanism of the reaction. As the market demand for each product fluctuates, the dynamic system developed here to meet changing demands is very important to obtain one of the products in excess quantities with a change of the ratio of Br^–/Cl^–.     

Formation of first gold(III) complex of an N(4)-disubstituted thiosemicarbazone derived from 2-benzoylpyridine: structural and spectral studies

The reaction between gold(III) chloride(AuCl₃) and 2-benzoylpyridine N(4), N(4)-(butane-1,4-diyl) thiosemicarbazone (HBpypTsc) leads to an unexpected formation of a first gold(III) complex from an N(4)-disubstituted thiosemicarbazone derived from 2-benzoylpyridine. The crystal structure, spectroscopic characterization, and preliminary biological activity of [Au(III)(Cl)(BpypTsc)][Au(I)Cl₂] complex are discussed herein.     

PEO:KIO3 Polymer electrolyte system- its application to solid state electrochemical cell

In search of polymer electrolyte based on PEO- salt complexes other than the extensively studied lithium-based polymer electrolytes, we report the new polymer electrolyte based on PEO complexed with KIO₃ salt. Several experimental techniques such as differential scanning calorimetry (DSC), composition dependence conductivity, temperature dependence conductivity and transport number measurements have been performed to characterize the polymer electrolyte. DSC study reveals that the melting temperature of pure PEO is shifting towards lower temperatures by complexing with the KIO₃ salt. The conductivity-temperature plots show two regions below and above the melting point (T_m). Transport numbers data suggest that the charge transport in this polymer electrolyte system is mainly due to ions. Using the polymer electrolyte films solid-state electrochemical cells have been fabricated and the discharge characteristics studied. The open circuit voltage (OCV) and short circuit current (SCC) are found to be 2.69 V and 346µA respectively.     

An efficient triazole-based fluorescent “turn-on” receptor for naked-eye recognition of F− and AcO−: UV–visible,fluorescence and 1H NMR studies

An efficient colorimetric receptor was developed by a simple convenient method which exhibited naked-eye sensitivity for fluoride and acetate in a biologically competing solvent like DMSO. The receptor developed, portrayed a substantial change in the UV–visible absorption characteristics upon addition of fluoride and acetate anions over other anions. The binding constants showed that the binding ability of receptor towards F^? anion was slightly higher than that of the AcO^? anion. Job's plots indicated the formation of a (1:1) complex (receptor:anion) of receptor with fluoride and acetate anions respectively. A “turn on” fluorescence response with a red shift was observed upon fluorescence titration. ¹H NMR titration experiments revealed the mechanism to be driven by the hydrogen bonding interaction of amide NH and phenol OH of the receptor molecule which was followed by deprotonation in the receptor by the F^? and AcO^? anions.     

NUMERICAL MODELLING OF MICROSCALE EFFECTS IN CONDUCTION FOR DIFFERENT THERMAL BOUNDARY CONDITIONS

Natural convection in a two-dimensional, rectangular enclosure with sinusoidal temperature profile on the upper wall and adiabatic conditions on the bottom and sidewalls is numerically investigated. The applied sinusoidal temperature is symmetric with respect to the midplane of the enclosure. Numerical calculations are produced for Rayleigh numbers in the range 10 2 to 10 8 , and results are presented in the form of streamlines, isotherm contours, and distributions of local Nusselt number. The circulation patterns are shown to increase in intensity, and their centers to move toward the upper wall corners with increasing Rayleigh number. As a result, the thermal boundary layer is confined near the upper wall regions. The values of the maximum and the minimum local Nusselt number at the upper wall are shown to increase with increasing Rayleigh number. Finally, an increase in the enclosure aspect ratio produces an analogous increase of the fluid circulation intensity.     

PREDICTION OF PSYCHROMETRIC PARAMETERS USING NEURAL NETWORKS

Abstract

A neural network approach was used for the prediction of the psychrometric parameters in a non-iterative manner. Neural network models were developed for the each of the three main variables - dry bulb temperature, wet-bulb temperature and relative humidity - as a function of the other two variables. Models were also developed for the prediction of the dew point temperature using the dry bulb and wet bulb temperatures, and for the saturation vapor pressure as a function of the dry bulb temperature. The sensitivity of the neural network performance to the form of input and output variables employed was also investigated. The prediction accuracy of the neural network models were found to be very good, with errors less than 4%.