ON THE UNIFORM DISSIPATIVITY OF SOME FIFTH-ORDER NON-LINEAR DIFFERENTIAL EQUATIONS

This paper studies the problem of uniformly dissipative solutions of somefifth order non-linear differential equations by the use of frequency domaintechnique. We use the generalized theorem of Yacubovich on dissipativity toobtain some new sufficient conditions of the existence of solutions that aredissipative for (1.1) and (1.2).     

Activities of δ-Al2O3-supported bimetallic Pt?NiO and Co?NiO catalysts for methane autoreforming: Oxidation studies

The methane oxidation activities of Pt−NiO and Co−NiO bimetallic catalysts have been investigated as part of a larger research program on the autothermal reforming of methane (combined methane oxidation and steam reforming) in a fluidized bed reactor. Experiments at atmospheric pressure and 783–1023 K for both catalysts showed that the reaction was more selective towards H₂ production at CH₄∶O₂ ratios greater than unity. Light-off temperature increased with decreasing CH₄∶O₂ ratios, but increase in gas velocity (beyond minimum fluidization) increased the light-off temperature. Co−NiO was as promising as the more expensive Pt−NiO catalyst for the oxidation.     

A review of CFC and halon treatment technologies – The nature and role of catalysts

The purpose of this review article is to provide readers with an account of CFC and halon treatment technologies as depicted in the patent and open literature. Destruction technologies, in which halons and CFCs are converted into species such as CO₂, HX or X₂ (X = Br, Cl, F), are treated less extensively. Emphasis has been placed on conversion processes, which aim at transforming (rather than destroying) CFC or halon into environmentally benign and useful products. It has been found that catalytic hydrodehalogenation over transition metal based catalysts, Pd in particular, has great potential for conversion of CFCs and halons to hydrofluorocarbons. In this regard, the focus of this review is on catalytic hydrodehalogenation, including an assessment of reaction mechanisms, catalytic activity, selectivity and durability.     

Multiple rate resonance phenomena in the forced composition cycling of the Fischer-Tropsch synthesis over a supported cobalt oxide catalyst

Experimental investigation of hydrocarbon synthesis from a mixture of CO and H₂ over a supported cobalt oxide catalyst showed pronounced resonance of the rate of formation of individual hydrocarbons with respect to the frequency of the feed compositon changes. When the measured concentrations of the synthesis products are time-averaged, the mean rate of formation for methane increases fivefold when compared with rate at the mean composition of the feed at steady state for a cycling frequency of 0.017 c/s. Another maximum occurs at about 0.00056 c/s, where the mean rate is about twice the steady-state rate. Rate resonance was also observed for higher hydrocarbons at similar frequencies but with smaller time-average rates. Resonance of rates of reaction has been observed for other catalysts, but rarely with multiple peaks and with such large magnitudes of the rate change.

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CO H₂ . , 0,017 /. 0,00056 /, . , , . , .

     

Highly efficient sorption of U(VI) from aqueous solution using amino/amine-functionalized magnetic mesoporous silica nanospheres

The amino/amine-functionalized magnetic mesoporous silica nanospheres (MSN-DETA) exhibited relatively high sorption capacity (q_m?=?153.68 mg/g) as well as excellent selectivity for U(VI). The U4f_7/2 X-ray photoelectron spectrometry revealed two binding energies at 380.8?±?0.3 eV (with the proportion of 75.2%) and 382.3?±?0.3 eV, which indicated the inner-surface complexation mechanism. The sorption isotherms fitted well with the Langmuir model, whereas the sorption kinetics could be fitted by pseudo-second-order model. The U(VI)-loaded MSN-DETA could be efficiently regenerated by acidified EDTA (0.4 M). These findings indicated that MSN-DETA could be used as a potential material for the efficient sorption/separation of U(VI) from wastewater.

     

Charge induced closing of Dionaea muscipula Ellis trap

In terms of bioelectrochemistry, Venus flytrap responses can be considered in three stages: stimulus perception, electrical signal transmission, and induction of mechanical and biochemical responses. When an insect touches the trigger hairs, these mechanosensors generate receptor potentials, which induce solitary waves activating the motor cells. We found that the electrical charge injected between a midrib and a lobe closes the Venus flytrap leaf by activating motor cells without mechanical stimulation of trigger hairs. The mean electrical charge required for the closure of the Venus flytrap leaf is 13.6 muC. To close the trap, electrical charge can be submitted as a single charge or applied cumulatively by small portions during a short period of time. Ion channel blocker such as Zn(2+) as well as an uncoupler CCCP, dramatically decreases the speed of the trap closing a few hours after treatment of the soil. This effect is reversible. After soil washing by distilled water, the closing time of Venus flytrap treated by CCCP or ZnCl(2) decreases back from 2-5 s to 0.3 s, but higher electrical charge is needed for trap closure. The mechanism behind closing the upper leaf of Venus flytrap is discussed.     

Effective adsorption of U(VI) from aqueous solution using magnetic chitosan nanoparticles grafted with maleic anhydride: equilibrium,kinetic and thermodynamic studies

The in situ formed magnetite nanoparticles was encapsulated by maleated chitosan to synthesize a novel magnetic chitosan nano-sorbent (MCN-MA) for the effective sorption of uranium. The sorption kinetics could be described by the pseudo-second-order model, whereas the sorption isotherms could be fitted to the Langmuir model (q _m = 187.9 mg/g). The MCN-MA showed higher U(VI) sorption capacities (compared to MCN) due to high affinity of carboxylate groups introduced from grafting maleic anhydride. Thermodynamic parameters indicate that U(VI) sorption is endothermic and feasible. The nano-size and magnetic property of the MCN-MA allow its efficient U(VI) sorption and facile magnetic separation from wastewaters.