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951.
Ajay K. Jain Sushma Agrawal Raj P. Singh 《Journal of Radioanalytical and Nuclear Chemistry》1979,54(1-2):171-182
A new inorganic ion-exchanger, zirconium tugnstoarsenate, has been synthesized which has been characterized by chemical analysis,
thermogravimetry, X-ray and infrared spectroscopy. The ion exchanger has been found to be stable in acids and neutral salt
solutions. The Kd values for 30 metal ions have been determined at pH 3–4 which show that the exchanger has high affinity for UO
2
2+
, ZrO2+, Cs+ and Tl+ ions. The variation of Kd for a number of metal ions as a function of concentration of nitric acid and ammonium nitrate has been investigated to elucidate
the probable exchange mechanism and to work out conditions for elution. Some binary separations, viz. Sr2+−Cs+, Sr2+−Rb+, Sr2+−Y3+, Fe3+−Al3+, Fe3+−Zn2+ and Zn2+−Hg2+ in trace amounts have been carried out on the column of the exchanger which demonstrate the utility of the exchanger in radionalytical
and analytical chemistry. 相似文献
952.
The oxidation of H2NOH is first-order both in [NH3OH+] and [AuCl4
–]. The rate is increased by the increase in [Cl–] and decreased with increase in [H+]. The stoichiometry ratio, [NH3OH+]/[AuCl4
–], is 1. The mechanism consists of the following reactions.
The rate law deduced from the reactions (i)–(iv) is given by Equation (v) considering that [H+] K
a.
The reaction (iii) is a combination of the following reactions:
The activation parameters for the reactions (ii) and (iii) are consistent with an outer-sphere electron transfer mechanism. 相似文献
953.
Diethyl telludi reacts with both copper(I) and copper(II) chloride to give polymeric chloro(diethyl telluride)copper(I) which is characterised by elemental analysis and by its IR and 1H NMR spectra. X-ray analysis shows that its structure contains infinite sheets in which two Et2Te ligands are bridged between two di-μ-chlorodicopper(I) cores. The CuTe distances are 2.535(1) and 2.625(1) Å and the geometry around both copper and tellurium atoms in that of a distorted tetrahedron. The angels around copper range from 95.5(1) to 122.6(1)° and around tellurium from 95.6(1) to 130.5(1)°. The crystals are monoclinic, C2/c with a 19.761(11), b 7.114(4), c 11.76(7) Å, β 111.17(1)°, V 1542(2) Å3, ?calcd 2.45 ?obsd 2.43 g/cm3Z = 8 for 1220 unique “observed” reflections and the structure refined to an R index of 0.0243. 相似文献
954.
Chuan Liang Feng Anika Embrechts Anita Bouma María García-Parajó Wolfram Domschke Holger Schönherr 《European Polymer Journal》2007,43(6):2177-2190
Thin spin-coated films of polystyrene-block-poly(tert-butyl acrylate) (PS690-b-PtBA1210) on various substrates are introduced as versatile, robust reactive platform for the immobilization of (bio)molecules for the fabrication of tailored biointerfaces. The films are characterized by high stability and (bio)reactivity due to the presence of a glassy PS and a reactive PtBA block, respectively. The selective deprotection of the tert-butyl-ester groups in the PtBA skin layer by hydrolysis under acidic conditions, the activation with N-hydroxysuccinimide and the subsequent derivatization with amino functionalized (bio)molecules were investigated. Based on contact angle, FTIR spectroscopy and XPS, fluorescence microscopy and AFM data, it was shown that the (bio)molecules were coupled covalently to the polymer films and that high molecular coverages up to ∼2.4 poly(ethylene glycol) (PEG) molecules per nm2 (Mn = 500 g/mol) were obtained. Organic dyes, polyamidoamine dendrimers, polypeptides, proteins and amino end-functionalized DNA were efficiently and homogeneously immobilized on the PS-PtBA platforms. Grafting of ω-amino functionalized PEG afforded surfaces with substantially reduced non-specific adsorption of proteins and DNA. Owing to the glassy nature of PS and the covalent amide linkages, the derivatized films showed excellent stability under a broad range of processing conditions. Finally, the viability of PS690-b-PtBA1210 platforms as versatile biointerfaces was demonstrated in DNA hybridization experiments, as well as cell-surface interaction studies using pancreatic cancer and K562 cells. 相似文献
955.
956.
Dr. Thomas B. Parsons Keisuke Yamamoto Thomas A. Taylor Ritu Raj Kim Wals Prof. Shabaz Mohammed Prof. Carol V. Robinson Prof. Justin L. P. Benesch Prof. Benjamin G. Davis 《Angewandte Chemie (International ed. in English)》2016,55(7):2361-2367
Glycosylation patterns in antibodies critically determine biological and physical properties but their precise control is a significant challenge in biology and biotechnology. We describe herein the optimization of an endoglycosidase‐catalyzed glycosylation of the best‐selling biotherapeutic Herceptin, an anti‐HER2 antibody. Precise MS analysis of the intact four‐chain Ab heteromultimer reveals nonspecific, non‐enzymatic reactions (glycation), which are not detected under standard denaturing conditions. This competing reaction, which has hitherto been underestimated as a source of side products, can now be minimized. Optimization allowed access to the purest natural form of Herceptin to date (≥90 %). Moreover, through the use of a small library of sugars containing non‐natural functional groups, Ab variants containing defined numbers of selectively addressable chemical tags (reaction handles at Sia C1) in specific positions (for attachment of cargo molecules or “glycorandomization”) were readily generated. 相似文献
957.
C. Ravi Dhas R. Venkatesh R. Sivakumar A. Moses Ezhil Raj C. Sanjeeviraja 《Ionics》2016,22(10):1911-1926
Electrochromic effect of cobalt oxide thin films was studied as a function of substrate temperature (573–673 K). Tricobalt tetraoxide (Co3O4) thin films were deposited on glass and fluorine-doped tin oxide (FTO) substrates by nebulized spray technique using cobalt nitrate as precursor material. The XRD patterns indicated (311) plane was dominant for all the films irrespective of the deposition temperature. Williamson-Hall (W-H) analysis was made to understand the strain variation in the prepared Co3O4 films under different deposition temperature by employing uniform deformation model (UDM). Scanning electron microscopy images revealed porous morphology for the film prepared at 623 K. The optical parameters such as refractive index (n), extinction coefficient (k), and band gap were derived from UV-visible spectra of Co3O4 films. The electrochromic performance of the deposited Co3O4 films was analyzed through cyclic voltammetry, chronocoulometry, chronoamperometry, and iono-optical studies. 相似文献
958.
Different SnO2 nanostructures (SnO2Ns) were directly electrodeposited on the surface of anodized copper (Cu) substrates via the potentiostatic electrodeposition method with addition of supporting electrolytes. The effects of the supporting electrolytes and the electrodeposition parameters on the evolution of nanostructures and on the electrochemical properties of the SnO2Ns were systematically investigated using field emission scanning electron microscope (FESEM) and electrochemical methods including cyclic voltammetry (CV) and chronoamperometry (CA). The results confirmed that SnO2Ns exhibit alloying/de-alloying reactions with Li+ ions versus Ag/AgCl in aqueous electrolyte solution (LiOH·H2O and Li2CO3). The super capacitor performance of the SnO2Ns was investigated in 0.5-M Na2SO4 aqueous solution, and the highest specific capacitance of 110 Fg?1 at a scan rate of 5 mV s?1 was obtained for SnO2 microspheres made up of nanocubes. Our study shows that supporting electrolytes and electrodeposition parameters play the significant role in the growth of SnO2Ns and its electrochemical properties. 相似文献
959.
Brahm?Raj?Singh Swati?RawalEmail author R.?K.?Sinha 《Applied Physics A: Materials Science & Processing》2016,122(6):605
In the present paper, we have carried out analysis of asymmetric light propagation in a chirped photonic crystal waveguide. The designed structures have hexagonal arrangement and square arrangement of silicon rods in air substrate. Dimensions of the defect rods are tailored, so that the proposed design structure works as an optical isolator. The transmission analysis of the structure reveals that it can act as an optical diode. We have plotted the extinction ratio and transmission analysis graphs for the structure, and it has been observed that the maximum output is obtained for telecom wavelength of 1.55 μm. Dispersion curves are obtained using the plane wave expansion method, and the transmission is simulated using finite element method. The proposed structures are applicable for photonic integrated circuits due to their simple and clear operating principle. 相似文献
960.
Sunil Mohan Gaurav Gautam Narendra Kumar Rakesh Kumar Gautam Anita Mohan Ashish Kr. Jaiswal 《Composite Interfaces》2016,23(6):493-502
AbstractAl-base composites with different amount of silica (5, 10, 15 and 20 wt.%) were developed using powder metallurgy route and compacts were sintered at 550 °C for 2 h. XRD analysis of all compositions was conducted for phases and amount of the second phase present. Morphology of the composites shows quite uniform distribution of the SiO2 particles but at higher percentage of SiO2 particles the clustering starts. Mechanical properties such as uniaxial compressive strength (UCS) and hardness were evaluated and it is seen that among all compositions, composite with 10 wt.% SiO2 has maximum UCS and hardness. Wear behavior of all composites was studied with sliding distance, applied loads, sliding velocity and composition. All composites show a linear increase in cumulative wear with distance and load. Wear rate with load increases continuously for all compositions, however, composite with 10 wt.% SiO2 revealed minimum wear rate with distance, sliding velocity and loads. Wear rate with sliding velocity increases sharply after attaining minima at 3 m/s sliding velocity. SEM analysis of wear tracks is in agreement with wear results. Al-10 wt.%SiO2 also shows minimum wear coefficient values for all loads, however, wear coefficient decreases with load for all compositions. 相似文献