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111.
Mannan Mehta Satheesh Krishnamurthy Suddhasatwa Basu Tony P. Nixon Aadesh P. Singh 《Materials Today Chemistry》2020
In the present study, pristine BiVO4, TiO2 and BiVO4/TiO2 core-shell heterostructured nanoparticles are prepared by hydrothermal methods and studied for structural, morphological, optical, photoelectrochemical water splitting and photocatalytic degradation of methylene blue as an organic pollutant. Both pristine BiVO4 and TiO2 exhibit poor PEC and PC performance under visible light illumination. However, an enhanced PEC and PC activity in BiVO4/TiO2 core-shell heterostructure is observed due to high solar energy absorption and superior charge separation properties in core-shell nanoparticles. The photoelectrode prepared using BiVO4/TiO2 core-shell nanoparticles exhibit a photocathode behavior and produced cathodic photocurrent, however, the pristine BiVO4 and TiO2 photoelectrodes act as photoanode and produced anodic photocurrent. This behavior of change in current direction is also observe in the Mott-Schottky analysis where the BiVO4/TiO2 core-shell nanoparticles photoelectrode exhibits the positive slow showing p-type semiconducting behavior. The change in cathodic photoresponse in core-shell nanoparticles in comparison to anodic photoresponse of BiVO4 and TiO2 nanoparticles is explained in terms of the variations in the work function values. These results highlight the advantages of core-shell nanoparticle of suitable materials for photocatalytic and photoelectrochemical applications. 相似文献
112.
Philip A. Baker Andrew F. Coffey Roger Epton Tony Johnson Edward J. Mole 《Macromolecular Symposia》1988,19(1):79-91
2, 4-Dinitrophenyl-L-phenylalanine has been coupled to L-, D-, and DL-amino acid phenyl esters pendant upon a polymer matrix. The esters had been prepared by di-isopropylcarbodiimide-mediated condensation, catalyzed by 4-dimethylaminopyridine. Reverse phase high pressure liquid chromatography (HPLC), using elution solvents consisting of 10 vol.-% trifluoroacetic acid in water/acetonitrile mixtures, has been used to investigate the 2,4-dinitrophenyl L-L and L-D dipeptide mixtures obtained on hydrazinolysis of each of the dipeptide-matrix assemblies. ‘Hydrazinolysis-HPLC’ has been used also to determine intermediate peptide homogeneity in ultra-high load solid (gel) phase synthesis with Boc amino acids. Cross-linked poly(N-[2-(4-hydroxyphenyl)ethyl]acrylamide) and two derived polymers incorporating spacer groups have been used as supports. The spacer groups made possible peptide C-terminal attachment by either HF-labile benzyl ester or HF-labile cyclohexyl ester bonds, while still incorporating the phenolic ester linkage susceptible to rapid hydrazinolytic scission. 相似文献
113.
Tony Huynh Andrew D. King Sang‐il Oum Maryam Verdian‐Rizi 《Journal of Graph Theory》2017,84(2):158-175
A graph is strongly even‐cycle decomposable if the edge set of every subdivision with an even number of edges can be partitioned into cycles of even length. We prove that several fundamental composition operations that preserve the property of being Eulerian also yield strongly even‐cycle decomposable graphs. As an easy application of our theorems, we give an exact characterization of the set of strongly even‐cycle decomposable cographs. 相似文献
114.
115.
Mathew A. Cleveland Nick A. Gentile Todd S. Palmer 《Journal of computational physics》2010,229(16):5707-5723
Implicit Monte Carlo (IMC) and Implicit Monte Carlo Diffusion (IMD) are approaches to the numerical solution of the equations of radiative transfer. IMD was previously derived and numerically tested on grey, or frequency-integrated problems [1]. In this research, we extend Implicit Monte Carlo Diffusion (IMD) to account for frequency dependence, and we implement the difference formulation [2] as a source manipulation variance reduction technique. We derive the relevant probability distributions and present the frequency dependent IMD algorithm, with and without the difference formulation. The IMD code with and without the difference formulation was tested using both grey and frequency dependent benchmark problems. The Su and Olson semi-analytic Marshak wave benchmark was used to demonstrate the validity of the code for grey problems [3]. The Su and Olson semi-analytic picket fence benchmark was used for the frequency dependent problems [4]. The frequency dependent IMD algorithm reproduces the results of both Su and Olson benchmark problems. Frequency group refinement studies indicate that the computational cost of refining the group structure is likely less than that of group refinement in deterministic solutions of the radiation diffusion methods. Our results show that applying the difference formulation to the IMD algorithm can result in an overall increase in the figure of merit for frequency dependent problems. However, the creation of negatively weighted particles from the difference formulation can cause significant numerical instabilities in regions of the problem with sharp spatial gradients in the solution. An adaptive implementation of the difference formulation may be necessary to focus its use in regions that are at or near thermal equilibrium. 相似文献
116.
We present in this paper a finite difference solver for Maxwell's equations in non‐staggered grids. The scheme formulated in time domain theoretically preserves the properties of zero‐divergence, symplecticity, and dispersion relation. The mathematically inherent Hamiltonian can be also retained all the time. Moreover, both spatial and temporal terms are approximated to yield the equal fourth‐order spatial and temporal accuracies. Through the computational exercises, modified equation analysis and Fourier analysis, it can be clearly demonstrated that the proposed triple‐preserving solver is computationally accurate and efficient for use to predict the Maxwell's solutions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
117.
Tony Tite Vassilios Myrianthopoulos Emmanuel Mikros Roxane Tenta Tzortzis Nomikos 《Tetrahedron》2010,66(50):9620-9628
A number of new pyrazolo[3,4-c] and [4,3-b]pyridine C-nucleosides, which can be viewed as 4- or 6-deazaformycin analogues were synthesized and examined as potential adenosine deaminase (ADA) inhibitors. The compounds were prepared through the condensation of a suitably substituted, lithiated 2- or 4-methylpyridine with tri-O-benzyl-d-ribonolactone, followed by borohydride reduction of the resulting hemiacetals, intramolecular Mitsunobu cyclisation of the derived diols, formation of the pyrazolopyridine ring system and subsequent removal of the protecting groups. These derivatives were designed on the structural basis provided by docking simulations performed within the enzyme catalytic site, however they demonstrated weak ADA inhibitory activity. Theoretical calculations assisted in the interpretation of the obtained biological data, thus providing guidance for rational structural modifications within this molecular scaffold. 相似文献
118.
Application-specific optimization of disordered nanoporous carbons remains a formidable challenge due to the difficulty in
accurately characterizing their microstructures with current empirical methods. Using molecular simulation techniques, we
investigated the adsorptive and diffusive behavior of argon in three models of disordered nanoporous carbons. We found that
the structural and morphological differences between these models gave rise to distinct phenomenological properties. The adsorptive
behavior of argon in both the low and high pressure regimes was enhanced dramatically in the models with more crystalline
microstructures. As for dynamic properties, we found that the adsorbent’s structure and energetic topology significantly alters
the rates of diffusion as well as the characteristics of the underlying diffusion mechanisms. 相似文献
119.
R. Alan Aitken Bernd Fodi Michael H. Palmer Alexandra M.Z. Slawin Jing Yang 《Tetrahedron》2012,68(29):5845-5851
The structures of pyridazine N-oxide, pyrimidine N-oxide and pyrazine N-oxide have been determined by X-ray diffraction for the first time. Comparison with theoretical predictions of the equilibrium structures using the B3LYP method together with a cc-pVTZ basis set, show close agreement with the structural parameters observed, and experimental dipole moments, which suggests that the charge distribution is realistic. An ‘atoms in molecules’ (AIM) analysis of the computed wave-functions shows total electron densities rather different from the classical picture of a dative bond, whereas the same wave-functions subjected to Mulliken analysis show a more conventional view of the electron distribution. This latter procedure allows a bond dipole analysis of the N-oxide charge distribution. 相似文献
120.
Using molecular dynamics simulations, we investigate the oscillatory behaviors of carbon nanotube oscillators containing sp3-hybridized defects formed by hydrogen chemisorption. It is found that the presence of these defects significantly affects the kinetic and potential energies of the nanotube systems, which in turn affects their oscillation periods and frequencies. We have also studied the oscillatory characteristics of the oscillators containing sp3-hybridized Stone-Wales defects. Our results show that it is possible to control the motion of the inner nanotube by introducing sp3-hybridized defects on the outer nanotube, which provides a potential way to tune the oscillatory behavior of nanotube oscillators. 相似文献