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361.
Ramaswamy Mani Mrinal Bhattacharya Christian Leriche Li Nie Sukh Bassi 《Journal of polymer science. Part A, Polymer chemistry》2002,40(19):3232-3239
Functional aliphatic copolyesters of succinic acid (SA) and citric acid (CA) were synthesized via direct copolycondensation in the presence of 1,4‐butanediol, with titanium(IV) butoxide as a catalyst. The effects of the comonomer and comonomer ratio on the polycondensation and the melting and glass‐transition temperatures were investigated. The melting temperature was very sensitive to the molar ratio of the SA–CA comonomer units. The chain extension of this poly(butylene succinate citrate) was carried out with hexamethylene diisocyanate. The intrinsic viscosity, crystallinity percentage, and rheological properties of these copolyesters were also studied. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3232–3239, 2002 相似文献
362.
M. Ramaswamy 《Journal of Radioanalytical and Nuclear Chemistry》1996,207(2):303-312
Silica-titania gels containing 25, 50 and 75 mol% TiO2 were prepared and the sorption of alkali and alkaline earth metal ions by these materials has been studied. Distribution coefficient values for Cs+ and Sr2+ ions were found to pass through broad maxima as a function of TiO2 content except in the case of Sr under alkaline conditions where there was a continuous increase. Capacity values also increased with TiO2 content and samples containing 50% (for K+ and Cs+), 75% (for Li+ and Na+) and 25%/50% (for Ca2+, Sr2+ and Ba2+) TiO2 exhibited maximum capacities. However, unlike with alkali metals, capacities of a given sorbent for the three alkaline earth ions were almost the same. Large capacities obtained for the latter ions seem to indicate a mineral-forming reaction with 25% and 50% materials. On the other hand, the 25% TiO2 gel seems to sorb Sr at trace level by an ion exchange mechanism. Coupled with its Cs sorption capability, this material may find potential use in large scale decontamination of low level waste solutions. 相似文献
363.
Henry G. Kuivila John L. Considine Ramaswamy H. Sarma Richard J. Mynott 《Journal of organometallic chemistry》1976,111(2):179-196
Carbon-13 NMR parameters for 33 organotin compounds with a variety of structurul features were investigated in order to obtain information about the relationship between their structure and 13C NMR parameters. It was found that the substitution of a proton by a trialkyltin group generally produces an upfield shift for the directly bonded carbon. The γ-nuclei usually resonate at lower fields except where there is appreciable steric strain while the β-carbons undergo relatively constant shifts of approximately 3.5 to 4.5 ppm to lower fields. The magnitude of direct bond coupling Jz-sfnc;1J(119Sn13C)z-sfnc; is influenced by the hybridization of the tin and the directly attached carbon atoms. In rigid organitins, the vicinal coupling constants show a Karplus type variation. In aliphatic organotins, the values of the vicinal119Sn13C coupling indicates a flexible molecular framework with a clear cut preference for certain conformations. 相似文献
364.
Power spectra for various tagged particle quantities in bulk extended simple point charge model water [H. J. C. Berendsen, J. R. Grigera, and T. P. Straatsma, J. Phys. Chem. 91, 6269 (1987)] are shown to have a regime with 1f(alpha) dependence on frequency f with alpha lying between 1 and 1.5 if the dynamical changes in the particular observable are sensitive to the multiple time-scale behavior of the hydrogen-bond network. The variations in mobility associated with the diffusional anomaly are mirrored in the scaling exponent alpha associated with this multiple time-scale behavior, suggesting that monitoring of 1f(alpha) behavior is a simple and direct method for linking phenomena on three distinctive length and time scales: the local molecular environment, hydrogen-bond network reorganizations, and the diffusivity. Our results indicate that experimental studies of supercooled water to probe the density dependence of 1f(alpha) spectral features, or equivalent stretched exponential behavior in time-correlation functions, will be of interest. 相似文献
365.
366.
In this paper, the thermodynamic equilibrium models for biomass gasification applicable to various gasifier types have been developed, with and without considering char. The equilibrium models were then modified closely matching the CH4 only or both CH4 and CO compositions from experimental data. It is shown that the modified model presented here based on thermodynamic equilibrium and taking into account local heat and mass considerations can be used to simulate the performance of a downdraft gasifier. The model can also be used to estimate the equilibrium composition of the syngas. Depending on the gasifier type and internal fluid flow, heat and mass transfer characteristics, with proper modification of the equilibrium model, a simple tool to simulate the operation and performance of varying types of biomass gasifier can be developed. 相似文献
367.
Renganathan Ramaswamy Venkatachalam Sridevi Sethuraman Sankararaman 《Reaction Kinetics and Catalysis Letters》2001,74(1):41-49
A double substrate uncatalyzed bromate oscillator is reported. Oscillations occur for several minutes, the color of the solution
alternating between dark brown and reddish yellow. The oscillatory wave form (Pt electrode) has a distinct pattern, with a
progressive increase in the amplitude and time interval. The presence of both substrates namely 8-hydroxyquinoline and malonic
acid is essential.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
368.
369.
Free-standing composite polymer membranes comprising of high molecular weight poly (ethylene oxide) (PEO) complexed with lithium perchlorate (LiClO4) and Li6La2BaTa2O12 (LLBTO) garnet oxide as filler were developed via standard solution-casting method. The as-synthesized composite membranes were investigated through powder x-ray diffraction (PXRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and impedance spectroscopy techniques for their phase, thermal, morphological, and electrical properties, respectively. The lithium ion conductivity of polymer composite membranes consisting of PEO8/LiClO4 with various weight percents (5, 10, 15, 20, 25, and 30) of LLBTO were evaluated. We demonstrated a significant enhancement in Li+ conductivity with the addition of LLBTO to the polymer-lithium salt complex. Among the investigated membranes, the composite containing 20 LLBTO wt% garnet oxide exhibits maximized room temperature (30 °C) Li+ conductivity of 2.03 × 10?4 S cm?1 and electrochemical stability greater than 4.5 V. 相似文献
370.