Computational investigations of Cu-embedded MoS<Subscript>2</Subscript> sheet for CO oxidation catalysis

Elevated amount of CO levels in the atmosphere poses serious health and environmental hazards. Oxidation of CO using suitable catalysts is one of the methods to control it. By means of DFT calculations, single Cu atom doped in S vacancy of MoS₂ nanosheet is studied for CO oxidation catalysis. Cu atom is strongly confined at the S-defective site of the MoS₂ sheet, possessing high energy barrier for the diffusion to its neighboring sites. Adsorption energy, charge transfer and orbital hybridization of CO and O₂ molecules adsorbed Cu-doped MoS₂ sheet reveal that O₂ is relatively more strongly adsorbed than CO. High adsorption energy of O₂ (??2.115 eV) and large charge transfer between O₂ and Cu–MoS₂ sheet (0.493e), compared to CO, make O₂ adsorption more favorable, which extenuates CO poisoning and hence helps in the efficient CO oxidation process. The complete oxidation of CO takes place in two steps: \( {\text{CO}} + {\text{O}}_{2} \to {\text{OOCO}} \) with activation energy of 0.201 eV, succeeded by \( {\text{OOCO}} + {\text{CO}} \to 2{\text{CO}}_{2} \) without any energy barrier. Our results show that the basal plane of MoS₂ sheet gets activated by embedding it with Cu metal, which can catalyze CO oxidation reaction effectively and without poisoning issues. The high activity, stability and low cost features can possibly encourage fabricating MoS₂-based catalysts for CO oxidation reaction.     

Behaviour of multiphase PVDF in (1−x)PVDF/(x)BaTiO<Subscript>3</Subscript> nanocomposite films: structural,optical, dielectric and ferroelectric properties

The present paper deals with the synthesis and characterization of (1?x)PVDF/(x)BaTiO₃ nanocomposite films with x?=?0.1, 0.2, 0.3, 0.4 and 0.5. The samples were synthesized by simple solution mixing method followed by tape casting process. FESEM images show the homogeneous dispersion of BaTiO₃ nanoparticles within the matrix of poly(vinylidene fluoride) (PVDF) with slight agglomeration. An improvement in the thermal stability of nanocomposite film is observed by TGA results. XRD as well as FTIR analysis indicate the α–β phase transition of PVDF in the nanocomposite films. The embedded BaTiO₃ forms an intermediate band among the PVDF structures and thus decreases the band gap of nanocomposite films by absorbing the wavelength of lower energies. The band gap of nanocomposite films for x?=?0.4 decreases to 2.4 eV as compared to 5.0 eV for pristine PVDF. The dielectric constant (?′) of pristine PVDF at 50 Hz is 8.9, which increases to 26.7 for (0.6)PVDF/(0.4)BaTiO₃ nanocomposite film. An increase in the charge storage ability is observed from PE loops, as (0.6)PVDF/(0.4)BaTiO₃ nanocomposite film has highest value of polarization (0.093 µC cm^?2) as compared to pristine PVDF (0.020 µC cm^?2). This shows an increase in the charge storage ability of (1?x)PVDF/(x)BaTiO₃ nanocomposite films as compared to pristine PVDF.     

Ceramide–palmitic acid complex based Curcumin solid lipid nanoparticles for transdermal delivery: pharmacokinetic and pharmacodynamic study

Curcumin is an important anti-inflammatory natural compound with low bioavailability which is due to poor solubility and absorption. Solid lipid nanoparticles (SLNs) loaded with Curcumin were formulated and evaluated for physical parameters and in vitro/ex vivo permeation. Further the optimised SLN was assessed for pharmacokinetic/pharmacodynamic considerations. SLNs were formulated by emulsion-solvent evaporation technique and evaluated for physical properties and in vitro drug release. Selected SLNs were evaluated for stability and then characterised for pharmacokinetic parameters and anti-inflammatory activity with reference to a commercial formulation. Spherical SLNs were obtained in the size range of 102–156 nm with negative potential. C-SLN category has shown highest entrapment efficiency. The order of drug release was S-SLN > G-SLN > C-SLN. Selected SLN formulation C-SLN-3 has shown good stability under various conditions. C-SLN-3 has demonstrated highest drug permeation through human skin and 171.623 mg drug content permeated in 24 h. It has also shown lowest lag time 0.375 h. Similarly, it has shown maximum value for C_max in in vivo determination and increased the bioavailability upto 68.12%. C-SLN-3 provided 90.75% edema inhibition in 6 h. Present study shows that nature of lipids and its physical-chemical properties are critical for SLN formulation and can be used for designing better drug delivery systems with optimum transdermal permeation.     

Adaptive locally affine-invariant shape matching

Matching deformable objects using their shapes are an important problem in computer vision since shape is perhaps the most distinguishable characteristic of an object. The problem is difficult due to many factors such as intra-class variations, local deformations, articulations, viewpoint changes and missed and extraneous contour portions due to errors in shape extraction. While small local deformations have been handled in the literature by allowing some leeway in the matching of individual contour points via methods such as Chamfer distance and Hausdorff distance, handling more severe deformations and articulations has been done by applying local geometric corrections such as similarity or affine. However, determining which portions of the shape should be used for the geometric corrections is very hard, although some methods have been tried. In this paper, we address this problem by an efficient search for the group of contour segments to be clustered together for a geometric correction using dynamic programming by essentially searching for the segmentations of two shapes that lead to the best matching between them. At the same time, we allow portions of the contours to remain unmatched to handle missing and extraneous contour portions. Experiments indicate that our method outperforms other algorithms, especially when the shapes to be matched are more complex.     

Using topic models for OCR correction

Despite several decades of research in document analysis, recognition of unconstrained handwritten documents is still considered a challenging task. Previous research in this area has shown that word recognizers perform adequately on constrained handwritten documents which typically use a restricted vocabulary (lexicon). But in the case of unconstrained handwritten documents, state-of-the-art word recognition accuracy is still below the acceptable limits. The objective of this research is to improve word recognition accuracy on unconstrained handwritten documents by applying a post-processing or OCR correction technique to the word recognition output. In this paper, we present two different methods for this purpose. First, we describe a lexicon reduction-based method by topic categorization of handwritten documents which is used to generate smaller topic-specific lexicons for improving the recognition accuracy. Second, we describe a method which uses topic-specific language models and a maximum-entropy based topic categorization model to refine the recognition output. We present the relative merits of each of these methods and report results on the publicly available IAM database.     

A General Method for Sensor Planning in Multi-Sensor Systems: Extension to Random Occlusion

Systems utilizing multiple sensors are required in many domains. In this paper, we specifically concern ourselves with applications where dynamic objects appear randomly and the system is employed to obtain some user-specified characteristics of such objects. For such systems, we deal with the tasks of determining measures for evaluating their performance and of determining good sensor configurations that would maximize such measures for better system performance. We introduce a constraint in sensor planning that has not been addressed earlier: visibility in the presence of random occluding objects. occlusion causes random loss of object capture from certain necessitates the use of other sensors that have visibility of this object. Two techniques are developed to analyze such visibility constraints: a probabilistic approach to determine “average” visibility rates and a deterministic approach to address worst-case scenarios. Apart from this constraint, other important constraints to be considered include image resolution, field of view, capture orientation, and algorithmic constraints such as stereo matching and background appearance. Integration of such constraints is performed via the development of a probabilistic framework that allows one to reason about different occlusion events and integrates different multi-view capture and visibility constraints in a natural way. Integration of the thus obtained capture quality measure across the region of interest yields a measure for the effectiveness of a sensor configuration and maximization of such measure yields sensor configurations that are best suited for a given scenario. The approach can be customized for use in many multi-sensor applications and our contribution is especially significant for those that involve randomly occurring objects capable of occluding each other. These include security systems for surveillance in public places, industrial automation and traffic monitoring. Several examples illustrate such versatility by application of our approach to a diverse set of different and sometimes multiple system objectives. Most of this work was done while A. Mittal was with Real-Time Vision and Modeling Department, Siemens Corporate Research, Princeton, NJ 08540.     

DFT Analysis of Vanadium Tris(Dithiolene)-Based Double-Gated Single-Electron Transistor

A double-gated single-electron transistor (SET) based on metal–organic complex vanadium tris(dithiolene) has been modelled and investigated for the operation and electrostatics analysis. Density functional theory and non-equilibrium Green’s function method have been opted for first-principle calculations. For the enhancement of the electrostatic control in the SET operation, an addition of a second gate to the basic configuration of SET has been implemented. The results of the energy calculations have shown the expected enhanced electrostatic control in the SET operation with the incorporation of the second gate. The total energies are used to calculate ionisation energy, affinity energy and addition energies, and have shown reduced values for the double-gated SET. Total energies are also used to plot charge stability diagrams and energy surface plots for different gate voltages, which depict the improved conduction process. Because of its sensitivity towards the molecule’s individual charge states, the resultant double-gated SET can be used as a charge sensor.     

Optimization of Groundwater Pumping and River-Aquifer Exchanges for Management of Water Resources

Water Resources Management - Multi-objective optimization problems can be solved through Simulation-Optimization (S-O) techniques where the pareto front gives the optimal solutions in the problem...