Hydrogen-iodide decomposition over PdCeO2 nanocatalyst for hydrogen production in sulfur-iodine thermochemical cycle

A highly active and stable catalyst for hydrogen-iodide decomposition reaction in sulfur-iodine (SI) cycle has been prepared in the form of PdCeO₂ nanocatalyst by sol-gel method with different calcination temperatures (300 °C, 500 °C, and 700 °C). XRD and TEM confirmed a size around 6–8 nm for PdCeO₂ particles calcined at 300 °C. Raman study revealed large number oxygen vacancies in PdCeO₂-300 when compared to PdCeO₂-500 and PdCeO₂-700. With increase in calcination temperature, the average particle size increased whereas the specific surface area and number of oxygen vacancies decreased. Hydrogen-iodide catalytic-decomposition was carried out in the temperature range of 400°C–550 °C in a quartz-tube, vertical, fixed-bed reactor with 55 wt % aqueous hydrogen-iodide feed over PdCeO₂ catalyst using nitrogen as a carrier gas. PdCeO₂-300 showed hydrogen-iodide conversion of 23.3%, which is close to the theoretical equilibrium conversion of 24%, at 550 °C. It also showed a reasonable stability with a time-on-stream of 5 h.     

A Note on Fractions of 34n+1 Plans

This paper is an exposition of the use of ridge regression methods. Two examples from the literature are used as a base. Attention is focused on the RIDGE TRACE which is a two-dimensional graphical procedure for portraying the complex relationships in multifactor data. Recommendations are made for obtaining a better regression equation than that given by ordinary least squares estimation.     

Experimental studies on semibatch reactor parametric sensitivity

Runaway behaviour of an exothermic reaction in a semibatch reactor was studied experimentally on the example of hydrolysis of acetic anhydride catalyzed by sulphuric acid, in a 700 cm³ thinwalled stainless steel stirred reactor, 10.2 cm in diameter and 13.0 cm high. The reactor was partially immersed, to a depth of 2.1 cm, in a thermostatic bath, in order to obtain sufficiently rapid cooling of its contents. A reaction run was performed by first introducing water, acetic acid and sulphuric acid into the reactor. After the contents attained bath temperature, acetic anhydride at room temperature was fed to the reactor for a fixed time period, at a constant flow rate. When water was present in excess of the stoichiometric requirement and addition of acetic anhydride completed before the reactor attained peak temperature, the system showed sensitivity to coolant temperature and sulphuric acid concentration. When the reactants were present in stoichiometric quantities and addition of acetic anhydride was completed after the reactor attained peak temperature, the system did not exhibit any significant parametric sensitivity.     

Influence of sugar ring conformation on the transportability of nucleosides by human nucleoside transporters

The conformational preference of human nucleoside transporters (hNTs) with respect to sugar ring was examined using conformationally fixed purine and pyrimidine nucleosides built on a bicyclo[3.1.0]hexane template. These fixed-conformation nucleosides, methanocarba-deoxyadenosine or methanocarba-deoxycytidine in North (C3'-endo, N-MCdA and N-MCdC) or South (C2'-endo, S-MCdA and S-MCdC) conformations, were used to study inhibition of equilibrative (hENT1-4) and concentrative (hCNT1-3) nucleoside transport by individual recombinant hNTs produced in Saccharomyces cerevisiae cells or Xenopus laevis oocytes. Our results indicated that nucleosides in the North conformation were potent inhibitors of transport mediated by hCNTs whereas South nucleosides were inhibitors of hENTs, thus showing differences in the interaction with the hNTs. In summary, hCNTs exhibited strong preferences for North nucleosides whereas hENTs exhibited slight preferences for South nucleosides, demonstrating for the first time different conformational preferences among members of the two families of hNTs.     

Plasma catalysis: a feasible solution for carbon dioxide valorization?

Clean Technologies and Environmental Policy - This review highlighted the current ongoing research in plasma technology and why this process needs to be explored in synergy with the other...     

Impedance spectroscopic determination of effect of temperature on the transport resistances of an electro-electrodialysis cell used for concentration of hydriodic acid

Effect of temperature on different transport resistances of an electro-electrodialysis (EED) cell used for concentration of hydriodic acid (HI) was found by equivalent circuit modeling of the measured impedance response of the cell. The EED cell consisted of two compartments separated by Nafion 117 membrane and each compartment had a platinum electrode. Both the compartments were filled with aqueous solution of 55?wt% HI containing 0.5?M iodine. Impedance measurements were carried out at four different temperatures in the range of 308?C353?K. Equivalent circuit for the cell consisted of a resistor for ohmic resistance of the cell, a Warburg element for the resistance due to diffusion boundary layer and a constant phase element for the resistance to transport of ions due to non-electro neutral heterogeneous transport layer at the membrane. Effect of temperature on impedance due to heterogeneous transport was lower than the Warburg impedance and the solution and membrane resistance. Effective capacitance of the heterogeneous transport layer was found to reduce with temperature. The dynamics of the heterogeneous transport layer along with the diffusional boundary layer were found to reduce with increase in the cell operating temperature.     

Experimental studies on parametric sensitivity of a batch reactor

Runaway behaviour of exothermic reactions in a batch reactor has been studied experimentally on the example of acetic anhydride hydrolysis catalyzed by sulphuric acid, in a 700 ml batch reactor. High parametric senstivities of peak reactor temperature with respect to initial reactor temperature and catalyst concentration were obtained.     

Pharmacodynamic profile of short-term abciximab treatment demonstrates prolonged platelet inhibition with gradual recovery from GP IIb/IIIa receptor blockade

BACKGROUND: The glycoprotein (GP) IIb/IIIa receptor antagonist abciximab is approved for use in high-risk percutaneous coronary interventions. The purpose of the present study was to establish the pharmacodynamic profile and platelet-bound life span of abciximab. METHODS AND RESULTS: The pharmacodynamics of abciximab (inhibition of ex vivo platelet aggregation and GP IIb/IIIa receptor blockade) were measured in 41 individuals who were randomized to receive a 0.25-mg/kg bolus and a 12-hour infusion of either 10 microg/min (EPIC regimen) or 0.125 microg x kg(-1) x min(-1) (EPILOG regimen) of the antiplatelet agent. At extended times, the amount and distribution of platelet-bound abciximab were monitored by flow cytometry. The EPIC and EPILOG infusion regimens exhibited equivalent blockade of both GP IIb/IIIa receptors and platelet aggregation throughout the duration of abciximab treatment. Flow cytometry revealed a single, highly fluorescent platelet population during treatment, consistent with complete saturation and homogeneous distribution of abciximab on circulating platelets. For 15 days after treatment, the fluorescence histograms remained unimodal with gradually diminishing fluorescence intensity, indicating decreasing levels of platelet-bound abciximab. At 8 and 15 days, which exceeds the normal circulating life span of platelets, median relative fluorescence intensity corresponded to 29100 (29% GP IIb/IIIa receptor blockade) and 13300 (13% GP IIb/IIIa receptor blockade) abciximab molecules bound per platelet, respectively. CONCLUSIONS: These results are consistent with continuous reequilibration of abciximab among circulating platelets and may explain the gradual recovery of platelet function and long-term prevention of ischemic complications by abciximab after coronary intervention.