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101.
ABSTRACTWe study the effect of the external electric field Fext on the low-temperature electron mobility μ in an asymmetrically doped AlxGa1-xAs based V-shaped double quantum well (VDQW) structure. We show that nonlinearity of µ occurs under double subband occupancy on account of intersubband effects. The field Fext alters the VDQW potential leading to transfer of subband wave functions between the wells, which affects the scattering potentials and hence μ. In the VDQW structure, due to the alloy channel layer, the alloy disorder (Al-) scattering happens to be significant along with the ionised impurity (Imp-) scattering. The non-linear behaviour of μ is because of μImp, while the overall magnitude of μ is mostly due to μAl. The increase of difference in the doping concentrations of the outer barriers increases the nonlinearity of μ. The oscillatory character of μ is amended by varying the width of the well and barrier and also the height of the VDQW. Our results can be used to study VDQW based nanoscale field effect transistor structures. 相似文献
102.
103.
This study compared eight major ginsenosides (Rg1, Rg2, Rf, Re, Rd, Rc, Rb1 and Rb2) between Panax sokpayensis and Panax bipinnatifidus collected from Sikkim Himalaya, India. High-performance liquid chromatographic analysis revealed that all major ginsenosides were present in the rhizomes of P. sokpayensis except ginsenoside Rc, whereas ginsenoside Rf, Rc and Rb2 were not detected in P. bipinnatifidus. 相似文献
104.
Kanungo BK Sahoo SK Baral M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(4):1452-1460
A novel multidentate tripodal ligand, cis,cis-1,3,5-tris[(2,3-dihydroxybenzylidene)aminomethyl]cyclohexane (TDBAC, L) containing one catechol unit in each arms of a tripodal amine, cis,cis-1,3,5-tris(aminomethyl)cyclohexane was investigated as a chelator for iron(III) through potentiometric and spectrophotometric methods in an aqueous medium of 0.1N ionic strength and 25+/-1 degrees C as well as in ethanol by continuous variation method. From pH metric in water, three protonation constants characterized for the three-hydroxyl groups of the catechol units at ortho were used as input data to evaluate the stability constants of the complexes. Formation of monomeric complexes FeLH3, FeLH2, FeLH and FeL were depicted. In ethanol, formation of complexes FeL, Fe2L and Fe3L were characterized. Structures of the complexes were explained by using the experimental evidences and predicted through molecular modeling calculations. The ligand showed potential to coordinate iron(III) through three imine nitrogens and three catecholic oxygens at ortho to form a tris(iminocatecholate) type complex. 相似文献
105.
Dr. Thangavel Vijayakanth Supriya Sahoo Premkumar Kothavade Vijay Bhan Sharma Prof. Dr. Dinesh Kabra Dr. Jan K. Zaręba Dr. Kadhiravan Shanmuganathan Prof. Dr. Ramamoorthy Boomishankar 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202214984
Hybrid materials possessing piezo- and ferroelectric properties emerge as excellent alternatives to conventional piezoceramics due to their merits of facile synthesis, lightweight nature, ease of fabrication and mechanical flexibility. Inspired by the structural stability of aminophosphonium compounds, here we report the first A3BX6 type cyanometallate [Ph2(iPrNH)2P]3[Fe(CN)6] ( 1 ), which shows a ferroelectric saturation polarization (Ps) of 3.71 μC cm−2. Compound 1 exhibits a high electrostrictive coefficient (Q33) of 0.73 m4 C−2, far exceeding those of piezoceramics (0.034–0.096 m4 C−2). Piezoresponse force microscopy (PFM) analysis demonstrates the polarization switching and domain structure of 1 further confirming its ferroelectric nature. Furthermore, thermoplastic polyurethane (TPU) polymer composite films of 1 were prepared and employed as piezoelectric nanogenerators. Notably, the 15 wt % 1 -TPU device gave a maximum output voltage of 13.57 V and a power density of 6.03 μW cm−2. 相似文献
106.
Dr. Shubham Dutta Dr. Rajendra K. Mallick Prof. Dr. Akhila K. Sahoo 《Angewandte Chemie (International ed. in English)》2023,62(30):e202300816
The use of ynamides in organic synthesis has gained significant attention due to their ability to provide access to complex molecular structures through transformations such as 1,2-difunctionalization and annulation reactions. These reactions enable the formation of highly functionalized N-bearing olefins and unusual N-bearing heterocycles. In this minireview, we present a systematic overview of the regioselective difunctionalization and annulation reactions of ynamides. We discuss the multi-component reactions, and radical-triggered functionalizations across the ynamides carbon–carbon multiple bonds and the use of bifunctional reagents in annulation of ynamides, highlighting their potential in expanding the substrate scope. Furthermore, we provide insights into the mechanistic breakthroughs that have been achieved in recent years in the development of these reactions. Finally, we emphasize the promising future prospects of ynamides as versatile building blocks for the synthesis of complex molecular architectures. 相似文献
107.
Dr. Anoop Kumar Kushwaha Sushri Soumya Jena Dr. Mihir Ranjan Sahoo Dr. Debashish Das Prof. Saroj Kumar Nayak 《Chemphyschem》2023,24(18):e202300032
High-voltage alkali metal-ion batteries (AMIBs) require a non-hazardous, low-cost, and highly stable electrolyte with a large operating potential and rapid ion conductivity. Here, we have reported a halogen-free high-voltage electrolyte based on SiB11(BO)12−. Because of the weak π-orbital interaction of −BO as well as the mixed covalent and ionic interaction between SiB11-cage and −BO ligand, SiB11(BO)12− has colossal stability. SiB11(BO)12− possesses extremely high vertical detachment energy (9.95 eV), anodic voltage limit (∼10.05 V), and electrochemical stability window (∼9.95 V). Furthermore, SiB11(BO)12− is thermodynamically stable at high temperatures, and its large size allows for faster cation movement. The alkali salts MSiB11(BO)12 (M=Li, Na, and K) are easily dissociated into ionic components. Electrolytes based on SiB11(BO)12− greatly outperform commercial electrolytes. In short, SiB11(BO)12−-based compound is demonstrated to be a high-voltage electrolyte for AMIBs. 相似文献
108.
The present study reports simultaneous mineralisation and biodetoxification of Ponceau S (3-hydroxy-4-(2-sulfo-4-[4-sulfophenylazo]phenylazo)-2,7-naphthalenedisulfonic acid sodium salt), an azo dye, by UV light assisted oxidation with hydroxyl and sulfate radicals. Metal ion catalysts used in the work were: Fe2+ and Ag+, and the oxidants used were: hydrogen peroxide and S2O82?. Strategies adopted to make the processes environmentally benign and economically viable by achieving maximum mineralisation in the shortest possible time are described. Mineralisation efficiency (Em) of various systems was found to follow the order: Em(Fe2+/H2O2/UV) > Em(Fe2+/S2O82?/UV) > Em(Ag+/H2O2/UV) ≈ Em(Ag+/S2O82?/UV). Thus, Fe2+ and HP are the most suitable metal ion catalyst and oxidant respectively, showing higher efficiency at pH 3 followed by that at pH 6.6. It is possible to enhance the Fe2+/H2O2/UV process electrical energy efficiency by maintaining the concentration of Fe at either 0.05 mM or 0.03 mM and that of the oxidant at 2.5 mM. The bioassay study revealed that the Fe2+/S2O82?/UV process biodetoxification efficiency is higher at pH 3 (93.7 %) followed by that at pH 6.6 (80.1 %) at the concentration of Fe 2+ and S2O82? of 0.03 mM and 2.5 mM, respectively. Thus, not only the concentration of Fe2+, but also the nature of the oxidant and pH play an important role in the biodetoxification process and S2O82? possesses higher biodetoxification efficiency than H2O2. 相似文献
109.
CPMD/GULP QM/MM interface for modeling periodic solids: Implementation and its application in the study of Y‐zeolite supported Rhn clusters 下载免费PDF全文
We report here the development of hybrid quantum mechanics/molecular mechanics (QM/MM) interface between the plane‐wave density functional theory based CPMD code and the empirical force‐field based GULP code for modeling periodic solids and surfaces. The hybrid QM/MM interface is based on the electrostatic coupling between QM and MM regions. The interface is designed for carrying out full relaxation of all the QM and MM atoms during geometry optimizations and molecular dynamics simulations, including the boundary atoms. Both Born–Oppenheimer and Car–Parrinello molecular dynamics schemes are enabled for the QM part during the QM/MM calculations. This interface has the advantage of parallelization of both the programs such that the QM and MM force evaluations can be carried out in parallel to model large systems. The interface program is first validated for total energy conservation and parallel scaling performance is benchmarked. Oxygen vacancy in α‐cristobalite is then studied in detail and the results are compared with a fully QM calculation and experimental data. Subsequently, we use our implementation to investigate the structure of rhodium cluster (Rhn; n = 2 to 6) formed from Rh(C2H4)2 complex adsorbed within a cavity of Y‐zeolite in a reducible atmosphere of H2 gas. © 2016 Wiley Periodicals, Inc. 相似文献
110.
Sahoo H Roccatano D Hennig A Nau WM 《Journal of the American Chemical Society》2007,129(31):9762-9772
Fluorescence resonance energy transfer (FRET) from the amino acid tryptophan (Trp) as donor and a 2,3-diazabicyclo[2.2.2]oct-2-ene-labeled asparagine (Dbo) as acceptor in peptides of the general structure Trp-(Pro)n-Dbo-NH2 (n = 1-6) was investigated by steady-state and time-resolved fluorescence, CD, and NMR spectroscopy as well as by molecular dynamics (MD) simulations (GROMOS96 force field). The Trp/Dbo FRET pair is characterized by a very short F?rster radius (R0 ca. 9 A), which allowed distance determinations in such short peptides. Water and propylene glycol were investigated as solvents. The peptides were designed to show an early nucleation of the poly(Pro)II (PPII) secondary helix structure for n > or = 2, which was confirmed by their CD spectra. The shortest peptide (n = 1) adopts preferentially the trans conformation about the Trp-Pro bond, as confirmed by NMR spectra. The FRET efficiencies ranged 2-72% and were found to depend sensitively on the peptide length, i.e., the number of intervening proline residues. The analysis of the FRET data at different levels of theory (assuming either a fixed distance or distance distributions according to a wormlike chain or Gaussian model) afforded donor-acceptor distances between ca. 8 A (n = 1) and ca. 16 A (n = 6) in water, which were found to be similar or slightly higher in propylene glycol. The distances afforded by the Trp/Dbo FRET pair were found to be reasonable in comparison to literature data, expectations from the PPII helix structure, and the results from MD simulations. The persistence lengths for the longer peptides were found to lie at 30-70 A in water and 220 +/- 40 A in propylene glycol, suggesting a more rigid PPII helical structure in propylene glycol. A detailed comparison with literature data on FRET in polyprolines demonstrates that the donor-acceptor distances extracted by FRET are correlated with the F?rster radii of the employed FRET pairs. This demonstrates the limitations of using FRET as a spectroscopic ruler for short polyprolines, which is presumably due to the breakdown of the point dipole approximation in F?rster theory, when the size of the chromophores becomes comparable or larger than the distances under investigation. 相似文献