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51.
[Cu32(H)20{S2P(OiPr)2}12]: The Largest Number of Hydrides Recorded in a Molecular Nanocluster by Neutron Diffraction
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Dr. Rajendra S. Dhayal Jian‐Hong Liao Dr. Samia Kahlal Dr. Xiaoping Wang Dr. Yu‐Chiao Liu Dr. Ming‐Hsi Chiang Prof. Werner E. van Zyl Prof. Jean‐Yves Saillard Prof. C. W. Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8369-8374
An air‐ and moisture‐stable nanoscale polyhydrido copper cluster [Cu32(H)20{S2P(OiPr)2}12] ( 1H ) was synthesized and structurally characterized. The molecular structure of 1H exhibits a hexacapped pseudo‐rhombohedral core of 14 Cu atoms sandwiched between two nestlike triangular cupola fragments of (2×9) Cu atoms in an elongated triangular gyrobicupola polyhedron. The discrete Cu32 cluster is stabilized by 12 dithiophosphate ligands and a record number of 20 hydride ligands, which were found by high‐resolution neutron diffraction to exhibit tri‐, tetra‐, and pentacoordinated hydrides in capping and interstitial modes. This result was further supported by a density functional theory investigation on the simplified model [Cu32(H)20(S2PH2)12]. 相似文献
52.
A new reversed stationary phase was prepared, based on thermal immobilization of trimethoxysilylpropyl modified polyethyleneimine onto silica particles endcapped with octadecyl molecules. The physicochemical and morphological properties of the stationary phase were characterized by solid state cross-polarization and magic angle spinning 29Si nuclear magnetic resonance, infrared spectroscopy, porosimetry, and elemental analysis. For the studies on reversed phase high-performance liquid chromatography (HPLC) retention, separation of the established Tanaka and Engelhardt test mixtures was performed. The stationary phase showed a typical partition mechanism for the reversed phase; however, the low hydrophobicity required a low organic content solvent in the mobile phase for chromatographic separation of more hydrophobic compounds. The stationary phase also showed low residual silanol activity for the elution of basic compounds due to the protection offered by octadecyl endcapped molecules and the competition provided by the imine groups of the polymeric layer. The proposed stationary phase possesses interesting selectivity and is convenient for applications requiring the separation of more retentive compounds in conventional HPLC columns using more aqueous mobile phases. 相似文献
53.
Anish Khan Aftab Aslam Parwaz Khan Abdullah M. Asiri Malik Abdul Rub Mohammed M. Rahman Sulaiman Ab. Ghani 《Mikrochimica acta》2014,181(9-10):1049-1057
A composite was prepared from copper and graphene oxide (Cu-GO) by in-situ chemical reduction of a mixture containing GO and Cu(II) ions with potassium borohydride. The morphology and structure of the composite were confirmed by various physicochemical techniques. The materials were used in a tyrosinase-based microbiosensor where the enzyme is immobilized in a biocompatible matrix consisting of poly(ortho-phenylene diamine) and Cu-GO. The composite was deposited on the surface of an 8-μm thick carbon fiber microelectrode. The role of each component in the sensing layer was systematically investigated with respect to the analytical performance of the system. In its optimal configuration, the biosensor demonstrated (a) a sensitivity of 6.1?±?3 nA mM-1 dopamine (DA), (b) a linear response to DA (with a Michaelis-Menten constant of 0.29?±?0.03 mM), (c) good selectivity over ascorbic acid and uric acid, and (d) a high blocking capacity (112.2?±?2 mM) for ascorbic acid. Figure
Poly(o-phenylenediamine) electropolymerized carbon fiber electrode with sensitivity towards dopamine (DA) is 6.1?±?3 nA mM?1 supported by Cu-GO. The linear range for DA is 0.29?±?0.03 mM with 0.033 μM LOD and fast response time of <8 s with ascorbic acid blocking capacity of 112.2?±?2 mM AA. Studies on different ratio of Glu/Tyr revealed that 10:3 gave best overall response. 相似文献
54.
55.
Afoulous S Ferhout H Raoelison EG Valentin A Moukarzel B Couderc F Bouajila J 《Molecules (Basel, Switzerland)》2011,16(10):8273-8291
Helichrysum gymnocephalum essential oil (EO) was prepared by hydrodistillation of its leaves and characterized by GC-MS and quantified by GC-FID. Twenty three compounds were identified. 1,8-Cineole (47.4%), bicyclosesquiphellandrene (5.6%), γ-curcumene (5.6%), α-amorphene (5.1%) and bicyclogermacrene (5%) were the main components. Our results confirmed the important chemical variability of H. gymnocephalum. The essential oil was tested in vitro for cytotoxic (on human breast cancer cells MCF-7), antimalarial (Plasmodium falciparum: FcB1-Columbia strain, chloroquine-resistant) and antioxidant (ABTS and DPPH assays) activities. H. gymnocephalum EO was found to be active against MCF-7 cells, with an IC(50) of 16 ± 2 mg/L. The essential oil was active against P. falciparum (IC(50) = 25 ± 1 mg/L). However, the essential oil exhibited a poor antioxidant activity in the DPPH (IC(50) value > 1,000 mg/L) and ABTS (IC(50) value = 1,487.67 ± 47.70 mg/L) assays. We have reviewed the existing results on the anticancer activity of essential oils on MCF-7 cell line and on their antiplasmodial activity against the P. falciparum. The aim was to establish correlations between the identified compounds and their biological activities (antiplasmodial and anticancer). β-Selinene (R2 = 0.76), α-terpinolene (R2 = 0.88) and aromadendrene (R2 = 0.90) presented a higher relationship with the anti-cancer activity. However, only calamenene (R2 = 0.70) showed a significant correlation for the antiplasmodial activity. 相似文献
56.
Rangel TB Assreuy AM Pires Ade F Carvalho AU Benevides RG Simões Rda C Silva HC Bezerra MJ Nascimento AS Nascimento KS Nagano CS Sampaio AH Delatorre P Rocha BA Fernandes PM Cavada BS 《Molecules (Basel, Switzerland)》2011,16(6):5087-5103
DwL, a lectin extracted from the seeds of Dioclea wilsonii, is a metalloprotein with strong agglutinating activity against rabbit and ABO erythrocytes, inhibited by glucose and mannose. DwL was purified by affinity chromatography on a Sephadex G-50 column and ion exchange chromatography on a HiTrap SP XL column. SDS-PAGE revealed three electrophoretic bands corresponding to the α (25,634 ± 2 Da), β (12,873 ± 2 Da) and γ (12,779 ± 2 Da) chains. Protein sequencing was done by Tandem Mass Spectrometry. The primary sequence featured 237 amino acids and was highly homologous to other reported Diocleinae lectins. A complete X-ray dataset was collected at 2.0 ? for X-Man-complexed DWL crystals produced by the vapor diffusion method. The crystals were orthorhombic and belonged to the space group I222, with the unit-cell parameters a = 59.6, b = 67.9 and c = 109.0 ?. DWL differed in potency from other ConA-like lectins and was found to induce neutrophil migration in rats, making it particularly useful in structural/functional studies of this class of proteins. 相似文献
57.
In this note we obtain generalization of well known results of carbone and Conti, Sehgal and Singh and Tanimoto concerning
the existence of best approximation and simultaneous best approximation of continuous funcitons from the set up of a normed
space to the case of a Hausdorff locally convex space. 相似文献
58.
Muhammad Aslam Noor Zhenyu Huang 《Journal of Mathematical Analysis and Applications》2002,274(1):59-68
In this paper, we suggest and analyze a three-step iterative scheme for solving nonlinear strongly accretive operator equation Tx=f without continuous condition in a uniformly smooth Banach space. Our results include the Ishikawa, Mann and Noor iterations as special cases. The results presented in this paper improve and extend almost all the current results in the more general setting. 相似文献
59.
In this paper we introduce and study a number of new classes of quasi variational inequalities. Using essentially the projection technique and its variant forms we prove that the generalized set-valued mixed quasivariational inequalities are equivalent to the fixed point problem and the Wiener-Hopf equations (normal maps). This equivalence enables us to suggest a number of iterative algorithms for solving the generalized variational inequalities. As a special case of the generalized set-valued mixed quasi variational inequalities, we obtain a class of quasi variational inequalities studied by Siddiqi, Husain and Kazmi [35], but there are several inaccuracies in their formulation of the problem, the statement and the proofs of their results. We have removed these inaccuracies. The correct formulation of their results can be obtained as special cases from our main results. 相似文献
60.
Abdellah Bnouhachem Muhammad Aslam Noor 《Journal of Mathematical Analysis and Applications》2006,324(2):1195-1212
In this paper, we suggest and analyze a new inexact proximal point method for solving general variational inequalities, which can be considered as an implicit predictor-corrector method. An easily measurable error term is proposed with further relaxed error bound and an optimal step length is obtained by maximizing the profit-function and is dependent on the previous points. Our results include several known and new techniques for solving variational inequalities and related optimization problems. Results obtained in this paper can be viewed as an important improvement and refinement of the previously known results. Preliminary numerical experiments are included to illustrate the advantage and efficiency of the proposed method. 相似文献