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41.
Prakashan P. Korambath Babu
B. K. Singaraju Shashi P. Karna 《International journal of quantum chemistry》2000,77(2):563-573
We have studied the structure and geometry of neutral and charged atomic clusters consisting of Ga and As atoms via ab initio Hartree–Fock (HF) and second‐order Møller–Plesset methods. The GamAsn cluster with m≠n composition prefers a nontetrahedral geometry in the charge neutral (q=0) state. These clusters tend to be stable in tetrahedral geometry when appropriately charged. The GamAsn cluster with m=n composition (1:1 ratio of Ga to As atoms) tends to be stable in a tetrahedral geometry in the charge neutral (q=0) state. With increasing size of the cluster, the geometry of GanAsn cluster approaches the zinc‐belende‐type crystalline structure. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 563–573, 2000 相似文献
42.
Sharbari Palmal SK Basiruddin Amit Ranjan Maity Dr. Sekhar C. Ray Dr. Nikhil R. Jana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(3):943-949
Fluorescent gold clusters (FGCs) with tunable emission from blue to red and quantum yields in the range of 6–17 % have been synthesized by simple modification of the conditions used for the synthesis of gold nanoparticles, namely by replacing the stronger reducing agent with a controlled amount of thiol. Various functional FGCs with hydrodynamic diameters of 5–12 nm have been successfully synthesized and used as cell labels. The results of our investigations strongly indicate that FGCs composed of Au0 are more stable imaging probes than commonly reported red/NIR‐emitting FGCs with a composition of Au0/AuI, as this combination rapidly transforms into nonfluorescent large clusters on exposure to light. The FGC‐based nanoprobes reported herein exhibit stable fluorescence upon continuous light exposure and can be used as imaging probes with low cytotoxicity. 相似文献
43.
SangWoo Kim Sandeep Karna JaeWoong Won Sang Mi Jeon Seo Yeon Kim YooDuk Choi HongRan Choi OkJoon Kim 《Photochemistry and photobiology》2013,89(1):199-207
Heat shock protein‐27 (HSP27) is a member of the small HSP family which has been linked to the nuclear factor‐kappa B (NF‐κB) signaling pathway regulating inflammatory responses. Clinical reports have suggested that low‐level light therapy/laser irradiation (LLLT) could be an effective alternative treatment to relieve inflammation during bacterial infection associated with periodontal disease. However, it remains unclear how light irradiation can modulate the NF‐κB signaling pathway. We examined whether or not 635 nm irradiation could lead to a modulation of the NF‐kB signaling pathway in HSP27‐silenced cells and analyzed the functional cross‐talk between these factors in NF‐κB activation. The results showed that 635 nm irradiation led to a decrease in the HSP27 phosphorylation, reactive oxygen species (ROS) generation, I‐κB kinase (IKK)/inhibitor of κB (IκB)/NF‐κB phosphorylation, NF‐κB p65 translocation and a subsequent decrease in the COX‐1/2 expression and prostaglandin (PGE2) release in lipopolysaccharide(LPS)‐induced human gingival fibroblast cells (hGFs). However, in HSP27‐silenced hGFs, no obvious changes were observed in ROS generation, IKK/IκB/NF‐κB phosphorylation, NF‐κB p65 translocation, nor in COX‐1/2 expression, or PGE2 release. This could be a mechanism by which 635 nm irradiation modulates LPS‐induced NF‐κB signaling pathway via HSP27 in inflammation. Thus, HSP27 may play a role in regulating the anti‐inflammatory response of LLLT. 相似文献
44.
Joshi P Shewale V Pandey R Shanker V Hussain S Karna SP 《Physical chemistry chemical physics : PCCP》2011,13(2):476-479
First principles density functional theory calculations are performed on tryptophan-ZnO nanoparticles complex in order to study site specific interactions between tryptophan and ZnO. The calculated results find the salt bridge structure involving the -COOH group and ZnO cluster to be energetically more favorable than other interacting sites, such as indole and amine groups in tryptophan. The interaction between tryptophan and ZnO appears to be mediated by both ionic and hydrogen bonds. The calculated molecular orbital energy levels and charge distributions suggest non-radiative energy transfer from an excited state of tryptophan to states associated with ZnO, which may lead to a reduction in the emission intensity assigned to the π-π* transition of the indole functional group of tryptophan. 相似文献
45.
Aspherical‐Atom Modeling of Coordination Compounds by Single‐Crystal X‐ray Diffraction Allows the Correct Metal Atom To Be Identified
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Dr. Birger Dittrich Claudia M. Wandtke Dr. Alke Meents Dr. Kartik Chandra Mondal Dr. Prinson P. Samuel Nurul Amin SK Dr. Amit Pratap Singh Prof. Dr. Herbert W. Roesky Dr. Navdeep Sidhu 《Chemphyschem》2015,16(2):412-419
Single‐crystal X‐ray diffraction (XRD) is often considered the gold standard in analytical chemistry, as it allows element identification as well as determination of atom connectivity and the solid‐state structure of completely unknown samples. Element assignment is based on the number of electrons of an atom, so that a distinction of neighboring heavier elements in the periodic table by XRD is often difficult. A computationally efficient procedure for aspherical‐atom least‐squares refinement of conventional diffraction data of organometallic compounds is proposed. The iterative procedure is conceptually similar to Hirshfeld‐atom refinement (Acta Crystallogr. Sect. A 2008 , 64, 383–393; IUCrJ. 2014 , 1,61–79), but it relies on tabulated invariom scattering factors (Acta Crystallogr. Sect. B 2013 , 69, 91–104) and the Hansen/Coppens multipole model; disordered structures can be handled as well. Five linear‐coordinate 3d metal complexes, for which the wrong element is found if standard independent‐atom model scattering factors are relied upon, are studied, and it is shown that only aspherical‐atom scattering factors allow a reliable assignment. The influence of anomalous dispersion in identifying the correct element is investigated and discussed. 相似文献
46.
Jack SK Chang Carolyn Chang Min Shi 《The Journal of the Operational Research Society》2015,66(3):405-420
We propose a novel market-based approach to optimum inventory control in a doubly stochastic jump-diffusion economy by modelling a commodity distributor’s inventory investment as a portfolio of forward commitments with explicit accounting of the jump-diffusion dynamics of demands, costs, and prices in open markets. We apply the robust real-asset martingale valuation methodology to derive a closed-form solution for the inventory value and a simple and intuitive optimality condition. Numerical analysis verifies this condition and demonstrates that the resulting optimum policy has robust properties in relation to the stylized effects. 相似文献
47.
Alcohol ethoxylates (AEs) are nonionic surfactants. They are industrially important compounds that have historically been difficult to analyze, with the best results to date achieved through derivatization (e.g., silylation) followed by analysis by gas chromatography/mass spectrometry (GC/MS). Recently, mass spectrometric techniques such as field desorption (FD), time-of-flight secondary ion mass spectrometry (TOF-SIMS), fast atom bombardment (FAB), electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) have been employed to analyze surfynol(R) 4xx. In an effort to produce low-cost alkyl-capped AEs and anionic detergents from AEs, a fast and reliable measure of the product yields and conversions from AEs is required in research. We found that the product yields and conversions from reactions of AEs, obtained by the employment of atmospheric pressure chemical ionization (APCI), were in good agreement with those obtained from proton nuclear magnetic resonance spectroscopy ((1)H-NMR). Therefore, APCI can be used as a validated tool for studying AE reactions. Mixtures that contain either silylated or unsilylated ethoxylates and/or carboxylates yield the same APCI mass spectra. Copyright -Copyright 1999 John Wiley & Sons, Ltd. 相似文献
48.
Ki Hwan Bae 《中国化学快报》2009,20(11):1321-1323
Phytochemical study on the BuOH-soluble fraction of the stem bark of Populus davidiana resulted in the isolation of a new salicin derivative(1),named davidianoside.The structure was elucidated on the basis of extensive physicochemical and spectroscopic analyses. 相似文献
49.
S Rayaprol Krushna Mavani CM Thaker DS Rana Keka Chakravorty SK Paranjape M Ramanadham Nilesh A Kulkarni DG Kuberkar 《Pramana》2002,58(5-6):877-880
A new series of mixed oxide superconductors with the stoichiometric composition La2−x
Dy
x
Ca
y
Ba2Cu4+y
O
z
(x=0.0 − 0.5, y=2x) has been studied for structural and superconductiong properties. Our earlier studies on La2−x
(Y/Er)
x
Ca
y
Ba2Cu4+y
O
z
series, show a strong dependence of T
c on hole concentration (p
sh). In the present work, the results of the analysis of the neutron diffraction measurements at room temprerature on x=0.3 and 0.5 samples are reported. It is interesting to know that Ca substitutes for both La and Ba site with concomitant
displacement of La onto Ba site. Superconductivity studies show that maximum T
c is obtained for x=0.5, y=1.0 sample (T
c ∼ 75 K), for La1.5Dy0.5Ca1Ba2Cu5O
z
(La-2125). 相似文献
50.
S. P. Karna F. Grein B. Engels S. D. Peyerimhoff 《International journal of quantum chemistry》1989,36(3):255-263
The isotropic (aiso) and dipolar (Adip) hyperfine coupling constants of 19F were obtained from MRD -CI wave functions using a variety of basis sets. In series I, increasing numbers of d functions were added to a 5s4p contracted Huzinaga/Dunning basis. In series II, the 5s3p basis set was uncontracted in several steps until 9s5p was reached, to which were added from one to three d-polarization functions. CI parameters (selection thresholds and the number of reference configurations) were also varied. A study of the R dependence of aiso and Adip was performed. The best values obtained at Re are 260 G for aiso and 308 G for Adip, compared with experimental values of about 280 G for aiso and 320 G for Adip. 相似文献