Passivity and passification of time-delay systems

In this paper, the problems of passivity and passification of a class of linear time-delay systems are investigated. A new state-transformation is developed to exhibit the delay-dependence. It is established that the passivity condition can be cast in a linear matrix inequality (LMI) format. For state feedback passification, it is proven that it is indifferent to use instantaneous or delayed state-feedback. The case of dynamic output feedback passification is also treated. Numerical examples are provided.     

Synthesis and Reactions of Some Fused Oxazinone,Pyrimidinone, Thiopyrimidinone,and Triazinone Derivatives with a Thiophene Ring as Analgesic,Anticonvulsant, and Antiparkinsonian Agents

Summary. A series of 2,6-disubstituted pyridine ester derivatives and the corresponding amides were prepared. The esters were hydrolysed to the sodium salts, which were treated with acetic anhydride to afford oxazinone derivatives. These were treated with ammonium acetate to afford 2-methylpyrimidinone derivatives, which were methylated to yield 2,3-dimethylpyrimidinone derivatives. In addition, they were reacted with aniline or hydrazine hydrate to give 3-phenyl- or 3-aminopyrimidinone derivatives. The latter reacted with 2-thiophenecarbaldehyde or phthalic anhydride to afford the corresponding Schiffs base and imide derivatives. Diazotization of amides gave thienotriazinone derivatives, which were treated with ethyl iodide to afford the corresponding 3-ethyltriazinone derivatives. Also, they were reacted with phenyl isothiocyanate to give the corresponding thiopyrimidinone derivatives, which were alkylated with ethyl iodide or chloroacetic acid to afford the corresponding thioethyl- or thioglycolic acid pyrimidinone derivatives.The pharmacological screening showed that many of these obtained compounds have good analgesic, anticonvulsant, and antiparkinsonian activities comparable to Voltarene®, Carbamazepine®, and Benzotropene® as reference drugs.Received January 23, 2003; accepted (revised) March 17, 2003 Published online September 15, 2003     

Radiation Polymerization of 4-(Acryloylamido)benzonitrile: Zinc and Copper Complexes

Summary. The new polymer containing cyano groups was synthesized by γ-irradiation. The oximated polymer was prepared using hydroxylamine hydrochloride in basic medium. The characterization of monomer, polymer, and oximated ones was confirmed by infrared and nuclear magnetic resonance spectroscopy. The complex formation of the amidoxime salt towards Zn^II, Cu^II, and Zn^II/Cu^II mixture in aqueous solution was studied by atomic absorption spectroscopy, energy dispersive spectroscopy, and electron spin resonance spectrometry. The significant binding capacity of these metal ions revealed its selectivity to Zinc(II) ion. The thermal stability of polymers and complexed ones was investigated using thermogravimetry analysis. The change in their morphology was observed by scanning electron microscopy (SEM).     

玻璃光波导元件检测氯仿蒸汽的研究

利用旋转甩涂法在钾离子交换玻璃光波导表面上固定甲基绿/聚乙烯醇薄膜，成功地检测氯仿蒸汽。实验结果表明，该元件对氯仿蒸汽有良好的响应，其线性响应范围为10×10^-3-90×10^-3（R=0.98674）。该元件具有响应恢复速度快、可逆性好、成本低和易制备等特点。     

Gradient Estimates in Fractional Dirichlet Problems

We obtain some fine gradient estimates near the boundary for solutions to fractional elliptic problems subject to exterior Dirichlet boundary conditions. Our results provide, in particular, the sign of the normal derivative of such solutions near the boundary of the underlying domain.

     

Enhanced methane decomposition over transition metal-based tri-metallic catalysts for the production of COx free hydrogen

In this study, COx-free hydrogen production via methane decomposition was studied over Cu–Zn-promoted tri-metallic Ni–Co–Al catalysts. The catalysts have been prepared by the constant pH co-precipitation method, and the nominal Ni metal loading was fixed at 50 wt % along with other metals at 10 wt% each. The catalyst activity for methane decomposition reaction was examined in a reactor between 400 °C and 700 °C and at atmospheric pressure. Different techniques such as N₂-physisorption, X-ray diffraction, H₂-TPR SEM, TEM, ICP-MS, TGA, and Raman spectroscopy were applied to characterize the catalysts. The relation between the catalyst composition and their catalytic activity has been investigated. The controlled synthesis has resulted in a series of catalysts with a high surface area. Ni–Co–Cu–Zn–Al was the most active and productive catalyst. Various characterizations indicate that the promotional effects of Cu–Zn interaction were the critical factor in catalysts' activity and stability. Ni–Co–Cu–Zn catalyst gave the highest methane conversion of 85% at 700 °C. Zn addition improves the stability of the catalyst by retaining the active metal size during the decomposition reaction. The catalyst was active for 80 h of stability study. The rapid deactivation of the Ni–Co catalyst was due to the sintering of the catalyst at 650 °C. Moreover, carbon species accumulated during the methane decomposition reaction depend on the catalysts' composition. Zn promotes the growth of reasonably long and thin carbon nanotubes, whereas the diameter of carbon nanotubes on unpromoted catalysts was large.     

Translational dynamics of a non-degenerate molecular shuttle imbedded in a zirconium metal–organic framework

A new [2]rotaxane molecular shuttle linker based on the binding of a 24-crown-8 ether macrocycle at a benzimidazole recognition site was synthesised. The shuttling dynamics of the linker were studied in solution and the structure confirmed by X-ray crystallography. A multivariate Zr(iv) MOF, UWDM-11, containing the new MIM linker and primary linker tetramethylterphenyldicarboxylate was synthesised and the translational motion of the molecular shuttle studied in the solid state. The use of a ¹³C enriched MIM linker allowed the dynamics of both activated and mesitylene-solvated UWDM-11 to be elucidated by VT ¹³C CPMAS SSNMR. The incorporation of mesitylene into the pores of UWDM-11 resulted in a significant increase in the barrier for thermally driven translation of the macrocycle.

An unsymmetrical molecular shuttle was incorporated into the octahedral cavities of a Zr(iv) MOF. ¹³C SSNMR showed that the presence of mesitylene in the pores results in an increase in the barriers for the thermally driven motion of the macrocycle.     

Synthesis and Reactions of Some Fused Oxazinone, Pyrimidinone, Thiopyrimidinone, and Triazinone Derivatives with a Thiophene Ring as Analgesic, Anticonvulsant, and Antiparkinsonian Agents

A series of 2,6-disubstituted pyridine ester derivatives and the corresponding amides were prepared. The esters were hydrolysed to the sodium salts, which were treated with acetic anhydride to afford oxazinone derivatives. These were treated with ammonium acetate to afford 2-methylpyrimidinone derivatives, which were methylated to yield 2,3-dimethylpyrimidinone derivatives. In addition, they were reacted with aniline or hydrazine hydrate to give 3-phenyl- or 3-aminopyrimidinone derivatives. The latter reacted with 2-thiophenecarbaldehyde or phthalic anhydride to afford the corresponding Schiffs base and imide derivatives. Diazotization of amides gave thienotriazinone derivatives, which were treated with ethyl iodide to afford the corresponding 3-ethyltriazinone derivatives. Also, they were reacted with phenyl isothiocyanate to give the corresponding thiopyrimidinone derivatives, which were alkylated with ethyl iodide or chloroacetic acid to afford the corresponding thioethyl- or thioglycolic acid pyrimidinone derivatives.The pharmacological screening showed that many of these obtained compounds have good analgesic, anticonvulsant, and antiparkinsonian activities comparable to Voltarene®, Carbamazepine®, and Benzotropene® as reference drugs.     

Synthesis, Reactions, and Anti-arrhythmic activity of Substituted Heterocyclic Systems Using 5-Chloroanisic Acid as Starting Material

Summary. A series of substituted heterocyclic systems were prepared from N1-[4-(4-fluorocinnamoyl)phenyl]-5-chloro-2-methoxybenzamide, which was prepared from the corresponding 5-chloroanisic acid (2-methoxy-4-chlorobenzoic acid) as starting material. Treating of the cinnamoyl derivative with hydrazine hydrate in dioxane afforded a pyrazoline, which was reacted with morpholine and paraformaldehyde to give the N-substituted pyrazoline. Acylation of pyrazoline with acetyl chloride in dioxane afforded the N-acetyl analogue. Also, the cinamoyl derivative was reacted with methylhydrazine, phenylhydrazine, or ethyl cyanoacetate to yield the corresponding N-methyl-, N-phenylpyrazoline, pyrane, and pyridone derivatives. Condensation of the cinnamoyl derivative with cyanothioacetamide gave the pyridinethione derivative, which was treated with ethyl chloroacetate affording the ethyl carboxylate derivative. Also, it was reacted with malononitrile or ethyl acetoacetae to give the cyano amino analougues and ethyl carboxylate, which was reacted with methylhydrazine to give the (indazolyl)phenyl derivative. On the other hand, reaction of cinnamoyl derivative with acetyl acetone afforded the cyclohexenyl derivative, which was reacted with hydrazine hydrate to give the [methylindazolyl]phenyl derivative. Condensation of the cinnamoyl derivative with guanidine hydrochloride or thiourea afforded the aminopyrimidine derivative and thioxopyrimidine. The latter was condensed with chloroacetic acid to yield a thiazolopyrimidine, which was condensed with 2-thiophenealdehyde to yield the arylmethylene derivative, however, it was also prepared directly from thiopyrimidine by the action of chloroacetic acid, 2-thiophenealdehyde, and anhydrous sodium acetate. The pharmacological screening showed that many of these compounds have good anti-arrhythmic activity and low toxicity.