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排序方式: 共有237条查询结果,搜索用时 15 毫秒
81.
Sagar C. Bhise Deepak V. Awale Madagonda M. Vadiyar Sandip K. Patil Balasaheb N. Kokare Sanjay S. Kolekar 《Journal of Solid State Electrochemistry》2017,21(9):2585-2591
Hierarchical CuO nanosheets were synthesized through a facile, eco-friendly reflux deposition approach for supercapacitor electrode material for energy storage. The resultant CuO nanosheets were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption isotherm techniques. The supercapacitor behavior of CuO nanosheets was investigated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy in novel 0.1 M aqueous 1-(1′-methyl-2′-oxo-propyl)-3-dimethylimidazolium chloride [MOPMIM][Cl] ionic liquid as an electrolyte. The result demonstrate that CuO nanosheets exhibit specific capacitance of 180 F g?1 at 10 mV s?1 scan rate which is the highest value in ionic liquid electrolyte and 87% specific capacitance retention after 5000th cycle. The electrochemical performance proves CuO nanosheets as electrode with ionic liquid electrolyte for developing green chemistry approach in supercapacitor. 相似文献
82.
Saúl J. C. Salazar Humberto G. Laguna Vinod Prasad Robin P. Sagar 《International journal of quantum chemistry》2020,120(11):e26188
The appearance of critical points in the Shannon entropy sum as a function of confinement radius, in ground and excited state confined hydrogenic systems, is discussed. We illustrate that the Coulomb potential in tandem with the hard sphere confinement are responsible for these points. The positions of these points are observed to vary with the intensity of the potential. The effects of the Coulomb potential on the system are further probed, by examining the differences between the densities of the confined atom and those of the particle confined in a spherical box, for the same confinement radius. These differences are quantified by using Kullback-Leibler and cumulative residual Kullback-Leibler distance measures from information theory. These measures detect that the effects of the Coulomb potential are squeezed out of the system as the confinement radius decreases. That is, the confined atom densities resemble the particle in a box ones, for smaller confinement radii. Furthermore, the critical points in the entropy sum lie in the same regions where there are changes in the distance measures, as the atom behaves more particle in a spherical box-like. The analysis is further complemented by examination of the derivative of the entropy sum with respect to confinement radius. This study illustrates the inhomogeneity in the magnitudes of the derivatives of the entropy sum components and their dependence on the Coulomb potential. A link between the derivative and the entropic force is also illustrated and discussed. Similar behaviors are observed when the virial ratio is compared to the entropic power one, as a function of confinement radius. 相似文献
83.
84.
Dynamic control of three-dimensional (3D) chemical patterns with both high precision and high speed is important in a range of applications from chemical synthesis, flow cytometry, and multi-scale biological manipulation approaches. A central challenge in controlling 3D chemical patterns is the inability to create rapidly tunable 3D profiles with simple and direct approaches that avoid complicated microfabrication. Here, we present the ability to rapidly and precisely create 3D chemical patterns using a single two-dimensional (2D) microfluidic platform. We are not only able to create these 3D patterns, but can rapidly switch from one mode to another (e.g. from a focused to a defocused pattern in less than 1 second) via simple changes in inlet pressures. A feedback control scheme with a pressure modulation mechanism controls the pressure changes. In addition to experiments, we conducted computational simulations for guiding the optimum design of the channels as well as revealing the sensitivity of the patterns to the channel dimensions; these simulations have high experimental correlations. We also show that microvortices play an important role in creating these tunable 3D patterns in this microfluidic platform. We quantitatively determine the degrees of the focused patterns in 2D cross-sections using a focus index with a 2D Gaussian function. Our integrated approach combining feedback control with simple microfluidics will be useful for researchers in diverse disciplines including chemistry, engineering, physics, and biology. 相似文献
85.
Halling MD Unikela KS Bodwell GJ Grant DM Pugmire RJ 《The journal of physical chemistry. A》2012,116(21):5193-5198
Solid-state NMR (ssNMR) and ab initio quantum mechanical calculations are used in order to understand and to better characterize the molecular conformation and properties of [2.2]paracyclophane and 1,8-dioxa[8](2,7)pyrenophane. Both molecules are cyclophanes, consisting of an aromatic ring assembly and a cyclic aliphatic chain connected to both ends of the aromatic portion. The aliphatic chain causes curvature in the six-membered aromatic ring structures. This led us to examine how the ring strain due to curvature affects the chemical shifts. Using X-ray structures of both [2.2]paracyclophane and 1,8-dioxa[8](2,7)pyrenophane as our starting model, we calculate the chemical shielding tensors and compare these data with those collected from the (13)C ssNMR FIREMAT experiment. We define curvature of [2.2]paracyclophane and 1,8-dioxa[8](2,7)pyrenophane using the π-orbital axis vector (POAV) pyramidalization angle (θ(p)). 相似文献
86.
Going for gold: The title reaction has been developed and demonstrates a wide substrate scope with respect to the 1,6-enynes and nitrones (see scheme; DCE = 1,2-dichloroethane, Tf = trifluoromethanesulfonyl). The results for the enantioselective versions are also presented. 相似文献
87.
Trina Dutta Shakri Banerjee Dhananjay Soren Sagar Lahiri Shinjinee Sengupta Juhi Augusta Rasquinha Anil K. Ghosh 《Applied biochemistry and biotechnology》2012,168(8):2358-2375
The present study explored both spontaneous and stress-induced deamidation in acid trehalase and endo-xylanase. An alteration in optimum pH by 1.5 units and optimum temperature by 20 °C accelerated the process of deamidation with a rise in isoaspartate formation and ammonia loss. Spontaneous deamidation during an enzyme-substrate reaction at physiological conditions resulted in accretion of isoaspartyl residues within the enzymes which gradually impaired their catalytic efficacy. Deamidation appeared to be more pronounced in endo-xylanase owing to its secondary structure conformation and high asparagine content. The active sites, Ala 549 in acid trehalase and His184 and Trp188 in endo-xylanase contributed to the loss of enzyme activity as they were flanking the deamidation-susceptible Asn residues. Protein l-isoaspartyl methyl transferase seemed to have a repairing capability, which enabled the heat-damaged enzymes to regain their partial activity as evident from there rise in K cat/K m. Endo-xylanase could regain 38.1 % of its biological activity while a lesser 17.5 % reactivation was obtained in acid trehalase. A unique protein l-isoaspartyl methyl transferase recognition site, Asn 151 was also identified in acid trehalase. A mass increment of the tryptic peptides of repaired enzyme due to methylation catalyzed by protein l-isoaspartyl methyl transferase substantiated the repair hypothesis. 相似文献
88.
A systematic exploration of thiophilic ability of o-iodoxybenzoic acid (IBX) for oxidative desulfurization to trigger domino reactions leading to new methodologies for synthesis of different azoles is described. A variety of highly substituted oxadiazoles, thiadiazoles, triazoles, and tetrazoles have been successfully synthesized in good to excellent yields, starting from readily accessible thiosemicarbazides, bis-diarylthiourea, 1,3-disubtituted thiourea, and thioamides. 相似文献
89.
The change-of-variables theorem of probability theory is applied to compute acoustic field and array beam power probability density functions (pdfs) in uncertain ocean environments represented by stratified, attenuating ocean waveguide models. Computational studies for one and two-layer waveguides investigate the functional properties of the acoustic field and array beam power pdfs. For the studies, the acoustic parameter uncertainties are represented by parametric pdfs. The field and beam response pdfs are computed directly from the parameter pdfs using the normal-mode representation and the change-of-variables theorem. For two-dimensional acoustic parameter uncertainties of sound speed and attenuation, the field and beam power pdfs exhibit irregular functional behavior and singularities associated with stationary points of the mapping, defined by acoustic propagation, from the parameter space to the field or beam power space. Implications for the assessment of orthogonal polynomial expansion and other methods for computing acoustic field pdfs are discussed. 相似文献
90.
S.J. Haralkar R.H. Kadam S.S More Sagar E. Shirsath M.L. Mane Swati Patil D.R. Mane 《Physica B: Condensed Matter》2012,407(21):4338-4346
The effect of Cr3+ substitution in Mg–Zn ferrite, with a chemical formula Mg0.5Zn0.5CrxFe2−xO4 (x=0.0–1.0), synthesized by a sol–gel auto-combustion reaction is presented in this paper. The resultant powders were investigated by various techniques, including X-ray diffractometry (XRD), transmission electron microscopy (TEM), infrared spectroscopy (IR), vibrating sample magnetometry (VSM), and DC resistivity. The XRD pattern revealed that the cubic spinel structure is maintained for the all the compositions. The particle sizes measured from XRD and TEM are in good agreement with each other. The cation distribution suggests that Mg2+, Cr3+ and Fe3+ have strong preference towards octahedral B-site. The theoretical lattice constant and experimental lattice constant match each other very well. The IR analysis supports the presently accepted cation distribution. The saturation magnetization decreases linearly with increasing Cr3+ content. Curie temperatures are obtained by the Laoria and AC susceptibility techniques. The dc resistivity has been investigated as a function of temperature and composition. 相似文献