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31.
Hasmat Khan Malobi Seth Atanu Naskar Sunirmal Jana 《Journal of Sol-Gel Science and Technology》2018,88(2):359-370
Nano noble metal coating on surface patterned mesoporous semiconductor thin film can play an important role in enhancing visible light harvesting efficiency (LHE) towards improvement in photoelectrochemical (PEC) activity of the material. In this work, one-dimensional (1D) and two-dimensional (2D) mesoscale surface patterns have been created on sol–gel-based titanium tin oxide (TSO) nanostructured thin film on pure silica/indium tin oxide-coated glass by soft lithography. The TSO film matrix is observed to be mesoporous and semicrystalline as evidenced from the structural characterization by transmission electron microscopy and measurement of atmospheric ellipso-porosimetry, respectively. The 2D patterned film exhibits maximum LHE value in visible wavelength region. Further film surface modification has been carried out by depositing nano Au coating onto the bare patterned TSO films by a low temperature solution technique. Under visible light, a significant improvement in PEC activity is found and the gold-coated patterned 2D film shows higher visible LHE as well as >2.7 times higher photocurrent density than bare 2D film. This facile fabrication strategy can create an avenue toward improvement in LHE vis-à-vis the PEC activity of mesoporous mixed metal oxide semiconductor thin film. 相似文献
32.
Dr. Sourav Sarkar Anushree Shil Suman Maity Dr. Yun Lim Jung Dr. Mingchong Dai Prof. Atanu Acharya Prof. Kyo Han Ahn 《Angewandte Chemie (International ed. in English)》2023,62(43):e202311168
Aryl alcohol-type or phenolic fluorophores offer diverse opportunities for developing bioimaging agents and fluorescence probes. Due to the inherently acidic hydroxyl functionality, phenolic fluorophores provide pH-dependent emission signals. Therefore, except for developing pH probes, the pH-dependent nature of phenolic fluorophores should be considered in bioimaging applications but has been neglected. Here we show that a simple structural remedy converts conventional phenolic fluorophores into pH-resistant derivatives, which also offer “medium-resistant” emission properties. The structural modification involves a single-step introduction of a hydrogen-bonding acceptor such as morpholine nearby the phenolic hydroxyl group, which also leads to emission bathochromic shift, increased Stokes shift, enhanced photo-stability and stronger emission for several dyes. The strategy greatly expands the current fluorophores’ repertoire for reliable bioimaging applications, as demonstrated here with ratiometric imaging of cells and tissues. 相似文献
33.
Dinda E Si S Kotal A Mandal TK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(18):5528-5537
A series of newly designed ascorbic acid based room temperature ionic liquids were successfully used to prepare quasi-spherical and anisotropic gold nanostructures in an aqueous medium at ambient temperature. The synthesis of these room temperature ionic liquids involves, first, the preparation of a 1-alkyl (such as methyl, ethyl, butyl, hexyl, octyl, and decyl) derivative of 3-methylimidazolium hydroxide followed by the neutralization of the derivatised product with ascorbic acid. These ionic liquids show significantly better thermal stability and their glass transition temperature (Tg) decreases with increasing alkyl chain length. The ascorbate counter anion of these ionic liquids acts as a reducing agent for HAuCl4 to produce metallic gold and the alkylated imidazolium counter cation acts as a capping/shape-directing agent. It has been found that the nature of the ionic liquids and the mole ratio of ionic liquid to HAuCl4 has a significant effect on the morphology of the formed gold nanostructures. If an equimolar mixture of ionic liquid and HAuCl4 is used, predominantly anisotropic gold nanostructures are formed and by varying the alkyl chain length attached to imidazolium cation of the ionic liquids, various particle morphologies can formed, such as quasispherical, raspberry-like, flakes or dendritic. A probable formation mechanism for such anisotropic gold nanostructures has been proposed, which is based on the results of some control experiments. 相似文献
34.
Atanu Chatterjee 《Complexity》2016,21(Z1):307-317
Complexity in nature is astounding yet the explanation lies in the fundamental laws of physics. The Second Law of Thermodynamics and the Principle of Least Action are the two theories of science that have always stood the test of time. In this article, we use these fundamental principles as tools to understand how and why things happen. In order to achieve that, it is of absolute necessity to define things precisely yet preserving their applicability in a broader sense. We try to develop precise, mathematically rigorous definitions of the commonly used terms in this context, such as action, organization, system, process, etc., and in parallel argue the behavior of the system from the first principles. This article, thus, acts as a mathematical framework for more discipline‐specific theories. © 2015 Wiley Periodicals, Inc. Complexity 21: 307–317, 2016 相似文献
35.
We have performed molecular dynamics (MD) simulation of the thermal denaturation of one protein and one peptide-ubiquitin and melittin. To identify the correlation in dynamics among various secondary structural fragments and also the individual contribution of different residues towards thermal unfolding, principal component analysis method was applied in order to give a new insight to protein dynamics by analyzing the contribution of coefficients of principal components. The cross-correlation matrix obtained from MD simulation trajectory provided important information regarding the anisotropy of backbone dynamics that leads to unfolding. Unfolding of ubiquitin was found to be a three-state process, while that of melittin, though smaller and mostly helical, is more complicated. 相似文献
36.
Double-stranded quasiperiodic copper mean arrangement has been studied in respect of its electronic property and thermoelectric signature. The two-arm network is demonstrated by a tight-binding Hamiltonian. The eigenspectrum of such aperiodic mesh that does not convey translational invariance, is significantly dependent on the parameters of the Hamiltonian. It is observed that specific correlation between the parameters obtained from the commutation relation between the on-site energy and overlap integral matrices can eventually modify the spectral nature and generate absolutely continuous energy spectrum. This part is populated by atypical extended states that has a large localization length substantiated by the flow of the hopping integral under successive real space renormalization group method steps. This sounds delocalization of single particle energy states in such non-translationally invariant networks. Further this can be engineered at will by selective choice of the relative strengths of the parameters. This precise correlation has a crucial impact on the thermoelectric behavior. Anomalous nature of thermoelectric coefficient may inspire the experimentalists to frame tunable thermo-devices. Specific correlations can help us to tune the continuous band and determine the band position at will. 相似文献
37.
Sharma S Vandana Ghoshal SK Arora P Dilbaghi N Chaudhury A 《Applied biochemistry and biotechnology》2009,159(2):310-316
In the present frame of work, Macrophomina phaseolina is encapsulated in silica matrices at various concentrations by low temperature sol-gel technique using tetraethylorthosilicate
(TEOS) as precursor. The optical and photophysical properties of these samples have been studied by second harmonics of Nd:YAG
laser at 532 nm. UV-visible absorption spectra of samples have been recorded and it is found that the absorption increases
with increase in concentration of fungus. Further, a decrease in output transmission intensity of the laser has been observed
with increase in fungus concentration. The temporal response of these samples has also been examined. The results show that
the fungus concentration can be measured within ∼15–20 min. This method of optical sensing of fungus in test sample is faster
than other techniques, such as the conventional colorimetric method which takes about 1 h. 相似文献
38.
Rashid H Bhattacharjee RR Kotal A Mandal TK 《Langmuir : the ACS journal of surfaces and colloids》2006,22(17):7141-7143
A simple and easier chemical method for preparing spongy gold nanocrystals has been developed on the basis of a modified-citrate reduction technique of the corresponding gold salt at 25 degrees C in the absence of template. These nanocrystals possessed autocatalytic behavior and exhibited pronounced catalytic activity in the borohydride reduction of 4-nitrophenol due to their unique spongy morphology. 相似文献
39.
Ananta Kumar Ghosh Debajyoti Ghoshal Michael G. B. Drew Golam Mostafa Nirmalendu Ray Chaudhuri 《Structural chemistry》2006,17(1):85-90
Two new cadmium (II) complexes [Cd(hmt)(dca)2]
n
(1) and [Cd3(hmt)2(SeCN)6(H2O)2]
n
(2) (hmt=hexamethylenetetramine, dca=dicyanamide) have been synthesized and characterized by X-ray single-crystal analysis.
The complex 1 is a 2D rectangular grid of octahedral cadmium (II) with CdN6 chromophore where cadmium centers are doubly bridged by dicyanamide and hmt along a-axis, which are interlinked by dicyanamide running along c-axis. Whereas, complex 2 is a 1D chain of octahedral cadmium (II) with a three-leg ladder topology running along a-axis. The Cd(II) centers are doubly bridged through SeCN (infinite rail) along a-axis and singly bridged by hmt (two-step rung) along c-axis, having cadmium centers with CdSe2N3O and CdSe2N4 chromophores. The adjacent chains through H-bonding between coordinated water and hmt, and SeSe interaction are extended to 2D supramolecular architecture. 相似文献
40.
Das AK Hübner R Sarkar B Fiedler J Záliš S Lahiri GK Kaim W 《Dalton transactions (Cambridge, England : 2003)》2012,41(29):8913-8921
The neutral title compounds with Q = 3,5-di-tert-butyl-o-quinone or 4,6-di-tert-butyl-N-phenyl-o-iminobenzoquinone (Q(x)) were studied by UV-vis-NIR spectroelectrochemistry and by EPR spectroscopy in the case of the odd-electron monocation and monoanion intermediates. Supported by DFT and TD-DFT calculations, the results indicate stepwise electron removal from predominantly ligand-based delocalised MOs on oxidation whereas the stepwise electron uptake on reduction involves unoccupied MOs with considerably metal-ligand mixed character. In both cases, the strong near-infrared absorption of the neutral precursors diminishes. In comparison to the ruthenium series, the osmium analogues exhibit larger transition energies from enhanced MO splitting and a different EPR response due to the higher spin-orbit coupling. The main difference between the quinone (1(n), 2(n)) and corresponding monoiminoquinone systems (3(n), 4(n)) is the shift of about 0.6 V to lower potentials for the monoimino analogues. While the absorption features do not differ markedly, the EPR data reflect a higher degree of covalent bonding for the complexes with monoimino ligands. 相似文献