Monotone method for a system of nonlinear mixed type implicit impulsive integro-differential equations in Banach spaces

In this paper, by using a monotone iterative technique in the presence of lower and upper solutions, we discuss the existence of solutions for a new system of nonlinear mixed type implicit impulsive integro-differential equations in Banach spaces. Under wide monotonicity conditions and the noncompactness measure conditions, we also obtain the existence of extremal solutions and a unique solution between lower and upper solutions.     

Canon-π Interactions. Synthesis and Crystal Structure of Palladium Complex:[K(DB18C6)]_2[Pd(SCN)_4]

Noncovalentinteractionsplayadominantroleinmanyforefrontareasofmodemchemistry,frommat6rialsdesigntOmolecularbiology.Recelltly,theK -ninteractionshaveattractedmuchattentionbecauseoftheionseleCtivityinpotaSsiumchannelsl.Inothersystem,Sunneretal.showedthefirsttimebymassspectrometrythatK bindstobenzeneinthegasPhase:.ThisfindingstimulatedthestUdyoftheK -xinteractions.Indeed,theK -ninteractalshavealsobeen,identifiedbyX-raysinglecrystaldistractionanalysisforseveralcompouxtds:Km-be~usor--Phenyl',…     

Synthesis of MCM-41 supported amino-palladium complex and its catalytic performance for heck reaction

Using MCM-41 as the supporter, a series of MCM-41 supported amino-palladium complexes has been prepared and characterized by XRD (X-ray diffraction) and XPS (X-ray photoelectron spectroscopy), etc. The XRD and XPS results indicate that the Pd coordinates with the -NH₂ groups on the MCM-41 surface, and the structure of MCM-41 has been not damaged. Its catalytic performance for Heck arylation of alkene with aryl iodide shows that the catalysts have high activity and stereoselectivity in 70–90°C. The product of Heck reaction is in E form. And the effect of the preparation condition of catalyst on the catalytic performance was examined. Translated form Chinese Journal of Organic Chemistry, 2008, 28(5) (in Chinese)     

Mössbauer studies on ultraporous Fe-Oxide/SiO2 aerogel

Magnetic aerogels with very low volume density of ～0.2 g/cm³ were prepared by sol-gel method and supercritical drying. The resulting materials were monolithic and displayed high surface area. By X-ray diffraction and Mössbauer spectroscopy the crystalline phase formed inside the mesopores of the SiO₂ matrix was identified as a spinel iron oxide. Comparison of the magnetic measurements with Mössbauer spectra at various temperatures contributed to the elucidation of the magnetic state of this nanocomposite system with restricted magnetic interactions, in particular its transition to a superparamagnetic state.     

Synthesis, optical and electroanalytical characterizations of a thiacalix[4](N-phenylazacrown-5)ether-BODIPY ionophore

Novel fluorogenic 1,3-alt thiacalix[4](N-phenylazacrown-5)ether ionophore has been synthesized by conjugation of the N-phenyl group with borondipyrromethene (BODIPY) fluorophore moiety. The ionophore exhibits pronounced off-on type fluorescent responses to some transition metal ions, in particular to Cu²⁺. In a PVC membrane electrode, distinct Ag⁺ selectivity was observed in potentiometric transduction.     

Ring‐opening polymerization of 1,4‐dioxan‐2‐one initiated by lanthanum isopropoxide in bulk

Lanthanum isopropoxide (La(OiPr)₃) has been synthesized and employed for ring‐opening polymerization of 1,4‐dioxan‐2‐one in bulk as a single‐component initiator. The influences of reaction conditions such as initiator concentration, reaction time, and reaction temperature on the polymerization were investigated. The kinetics indicated that the polymerization is first‐order with respect to the monomer concentration. The Mechanistic investigations according to ¹H NMR spectrum analysis demonstrated that the polymerization of PDO proceeded through a coordination‐insertion mechanism with a rupture of the acyl‐oxygen bond of the monomer rather than the alkyl‐oxygen bond cleavage. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5214–5222, 2008     

多项式的特征和与二项指数和的混合均值

本文主要利用解析方法以及二项指数和与Dirichlet特征的性质，研究多项式的特征和与二项三次指数和的混合均值的计算问题，并得到一个较强的渐近公式.     

Local bifurcations of critical periods for cubic Liénard equations with cubic damping

Continuing Chicone and Jacobs’ work for planar Hamiltonian systems of Newton’s type, in this paper we study the local bifurcation of critical periods near a nondegenerate center of the cubic Liénard equation with cubic damping and prove that at most 2 local critical periods can be produced from either a weak center of finite order or the linear isochronous center and that at most 1 local critical period can be produced from nonlinear isochronous centers.