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71.
Role of liquid phase stability on the glass forming ability (GFA) has been reviewed and the alloy systems have been analyzed by introducing a contribution factor (wg) to the characteristic temperature Tg, in the γ parameter. The kinetics of glass formation for various alloy systems has been found to vary with liquid phase stability in metastable state. The GFA of a fragile liquid is found to be more responsive to the contribution of metastable stability compared to strong liquid. 相似文献
72.
73.
Piyush S. Sharma Marcin Dabrowski Krzysztof Noworyta Tan-Phat Huynh Chandra B. KC Janusz W. Sobczak Piotr Pieta Francis D’Souza Wlodzimierz Kutner 《Analytica chimica acta》2014
For molecular imprinting of oxidatively electroactive analytes by electropolymerization, we used herein reductively electroactive functional monomers. As a proof of concept, we applied C60 fullerene adducts as such for the first time. For that, we derivatized C60 to bear either an uracil or an amide, or a carboxy addend for recognition of the adenosine-5′-triphosphate (ATP) oxidizable analyte with the ATP-templated molecularly imprinted polymer (MIP-ATP). Accordingly, the ATP complex with all of the functional monomers formed in solution was potentiodynamically electropolymerized to deposit an MIP-ATP film either on an Au electrode of the quartz crystal resonator or on a Pt disk electrode for the piezoelectric microgravimetry (PM) or capacitive impedimetry (CI) determination of ATP, respectively, under the flow-injection analysis (FIA) conditions. The apparent imprinting factor for ATP was ∼4.0. After extraction of the ATP template, analytical performance of the resulting chemosensors, including detectability, sensitivity, and selectivity, was characterized. The limit of detection was 0.3 and 0.03 mM ATP for the PM and CI chemosensor, respectively. The MIP-ATP film discriminated structural analogues of ATP quite well. The Langmuir, Freundlich, and Langmuir–Freundlich isotherms were fitted to the experimental data of the ATP sorption and sorption stability constants appeared to be nearly independent of the adopted sorption model. 相似文献
74.
Harsh Kumar Meenu Singla Rajeev Jindal 《Monatshefte für Chemie / Chemical Monthly》2014,145(4):565-575
75.
Graft copolymerization of ethylmethacrylate (EMA) onto soy protein concentrate (SPC) was carried-out using ascorbic acid/potassium persulphate as redox initiator under microwave radiations. Different reaction parameters like reaction time, solvent amount, initiator ratio, pH and monomer concentration were optimized to get maximum graft yield (78.8%). The graft copolymer formed was characterized by FTIR, XRD, SEM, TGA, DTA and DTG techniques. Graft copolymer showed higher moisture resistance along with increased chemical and thermal stability. TGA, DTA and DTG studies could reveal the distinctive features of graft copolymerization of EMA onto S-S linkages of soy protein concentrate under the influence of microwave irradiations in addition to grafting at peptide linkages, which were further supported by FT-IR studies. 相似文献
76.
77.
Harbans L. Jindal Kiyoshi Matsuda Reita Tamamushi 《Journal of Electroanalytical Chemistry》1978,90(2):185-196
The electrochemical kinetic parameters for the polarographic reduction of Zn(II) at a dropping mercury electrode in concentrated supporting electrolytes consisting of sodium, ammonium, lithium, magnesium and calcium nitrates and sodium perchlorate have been determined at 25.0±0.1°C by the square-wave polarographic method. The rate parameter decreased with increase of radius of the alkali-metal cations present in the electrolyte and with increase of charge of the cation of the electrolyte in solution of the same ionic strength. It also decreases, passes through a minimum and then increases with the increase in the concentration of any of the supporting electrolytes. The initial decrease is ascribed to the Frumkin double-layer effect but the latter increase has been explained in terms of the change in the activity of water around the electrode. 相似文献
78.
Sunil Kumar Zinki Jindal Nitu Kumari Narendra Kumar Verma 《Journal of nanoparticle research》2011,13(10):5465-5471
To exploit the photoluminescent behavior of CdS at nanoscale with different doping concentration of europium—a rare earth
element, we report the synthesis of Eu-doped CdS nanorods by using low temperature solvothermal process by using ethylenediamine.
The outcomes can have future applications as phosphors, photovoltaic cells, lasers, light emitting diodes, bio-imaging, and
sensors. The doping was confirmed by electron dispersive spectroscopy supported by X-ray diffraction. From scanning electron
microscopy and transmission electron microscopy analysis it was observed that the average diameter of the Cd1−x
Eu
x
S nanorods is about 10–12 nm having lengths in the range of 50–100 nm. UV–Visible spectroscopy study was carried out to determine
the band gap of the nanorods and the absorbance peaks showed blue shift with respect to the bulk CdS. The blue shift was also
observed as the doping concentration of Eu increases. From photoluminescence (PL) studies at λex = 450 nm, peaks at 528 and 540 nm were observed due to CdS, peak at 570 nm is due to defects related transitions, while the
peak at 613 nm is due to Eu. As the doping concentration of Eu is increased the intensity of the luminescent peak at 613 nm
is increased. Thermogravimetric analysis showed the nanorods are thermally stable up to 300 °C. The traces of impurities adsorbed
on the nanorods were confirmed by Fourier transform infrared spectroscopy. 相似文献
79.
Lumata L Jindal AK Merritt ME Malloy CR Sherry AD Kovacs Z 《Journal of the American Chemical Society》2011,133(22):8673-8680
Hyperpolarized (89)Y complexes are attractive NMR spectroscopy and MR imaging probes due to the exceptionally long spin-lattice relaxation time (T(1) ≈ 10 min) of the (89)Y nucleus. However, in vivo imaging of (89)Y has not yet been realized because of the low NMR signal enhancement levels previously achieved for this ultra low-γ(n) nucleus. Here, we report liquid-state (89)Y NMR signal enhancements over 60,000 times the thermal signal at 298 K in a 9.4 T magnet, achieved after the dynamic nuclear polarization (DNP) of Y(III) complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) samples at 3.35 T and 1.4 K. The (89)Y DNP was shown to proceed by thermal mixing and the liquid state (89)Y NMR signal enhancement was maximized by (i) establishing the optimal microwave irradiation frequency, (ii) optimizing the glassing matrix, (iii) choosing a radical with negligible inhomogeneous line broadening contribution to the ESR linewidth, and (iv) addition of an electron T(1e) relaxation agent. The highest enhancements were achieved using a trityl OX063 radical combined with a gadolinium relaxation agent in water-glycerol matrix. Co-polarization of (89)YDOTA and sodium [1-(13)C]pyruvate showed that both (89)Y and (13)C nuclear species acquired the same spin temperature, consistent with thermal mixing theory of DNP. This methodology may be applicable for the optimization of DNP of other low-γ(n) nuclei. 相似文献
80.