Positive solutions for nonlinear operator equations and several classes of applications

In this paper, we study a class of nonlinear operator equations x = Ax + x ₀ on ordered Banach spaces, where A is a monotone generalized concave operator. Using the properties of cones and monotone iterative technique, we establish the existence and uniqueness of solutions for such equations. In particular, we do not demand the existence of upper-lower solutions and compactness and continuity conditions. As applications, we study first-order initial value problems and two-point boundary value problems with the nonlinear term is required to be monotone in its second argument. In the end, applications to nonlinear systems of equations and to nonlinear matrix equations are also considered.     

Fractional Sobolev,Moser–Trudinger,Morrey–Sobolev inequalities under Lorentz norms

We consider the Sobolev type inequalities under Lorentz norms on bounded open domains for fractional derivatives (−∆) ^s/2 in the following three cases: n > ps, n = ps, and n < ps, whence establishing the weak type Sobolev inequalities, Moser–Trudinger and Morrey–Sobolev inequalities for fractional derivatives in Lorentz norms. Applying these inequalities, we obtain the trace forms of six related functional inequalities. Bibliography: 44 titles.     

Methoxy poly (ethylene glycol) thiosulfonate: new activated polymer derivatives for thiol‐specific modification

Thiol‐reactive methoxy poly (ethylene glycol) (mPEG) derivatives, mPEG methanethiosulfonate (mPEG‐MTS) and mPEG phenylthiosulfonate (mPEG‐PTS), were synthesized by one‐step S‐alkylation of mPEG‐halide with the corresponding sodium thiosulfonate. These functionalized polymers were fully characterized by ¹H NMR, ¹³C NMR, GPC as well as MALDI‐TOF. To demonstrate the potential application of mPEG‐MTS and mPEG‐PTS, papain and recombinant human granulocyte colony‐stimulating factor (rhG‐CSF) were used as prototype protein for thiol‐selective PEGylation. The PEGylated products were verified by one or more of the following methods: SDS‐PAGE, HPLC, HPSEC as well as MALDI‐TOF. Compared with native rhG‐CSF, the PEGylated rhG‐CSF was further characterized by in vitro cell proliferative assay and preserved 59% biological activity. Furthermore, mPEG20k‐MTS was used to modify BSA nanoparticles coated with thiol groups. FT‐IR and ζ‐potential assay demonstrated that mPEG thiosulfonate can be effectively immobilized at the nanoparticles' surface via disulfide linkage to form hydrophilic and neutral corona. Therefore, we have demonstrated thiol‐selective PEG derivatives, endowed with unusual versatility, for practical use and potential exploitation. Copyright © 2009 John Wiley & Sons, Ltd.     

Effects of switching pulse width and stress on properties of Bi3.25La0.75Ti3O12 thin films

Polycrystalline ferroelectric Bi3.25La0.75Ti3O12 thin films are prepared on Pt/Ti/SiO2/Si substrates by the conventional metalorganic decomposition method.It is observed that with the increase of switching pulse width,the remnant polarisation and the coercive field increase.A wider switching pulse can result in poorer fatigue properties,which comes from more charged defects diffusing to and being trapped on domain walls.On the other hand,when the compressive stress is applied to films,the fatigue properties can be improved.This phenomenon is due to the reorientation of domains under stress.     

Rapid Extraction of Essential Oil from Dried Cinnamomum cassia Presl and Forsythia suspensa(Thunb.)Vahl by Ionic Liquid Microwave Extraction

Ionic liquid (IL) was used as the microwave absorption medium to extract essential oils from dried Cinnamomum cassia Presl and Forsythia suspensa (Thunb.) Vahl, and the ionic liquid microwave extraction (ILME) was developed. Some experimental parameters for ILME were examined. The proposed method was compared with other methods, including hydrodistillation (HD), microwave hydrodistillation (MHD), solvent‐free microwave extraction (SFME) and improved solvent‐free microwave extraction (ISFME). Experimental results showed that compared with other extraction methods the ILME had some advantages, such as time‐saving, simplicity and usage of green solvents. The extraction time was less than 18 min at the microwave power of 440 W and 1.5 mL of ionic liquid was required. The constituents of essential oils obtained by the five methods are not obviously different.     

A new sesquiterpene from hairy root culture of Artemisia annua

<正>A new sesquiterpene(Z)-7-acetoxy-methyl-11-methyl-3-methylenedodeca-1,6,10-triene(AMDT) was isolnted and identified from the methanol extract of the hairy root culture of Artemisia annua.The structure of AMDT was determined based on the analysis of spectroscopic data,notably of the 2D NMR spectra.This new compound showed cytotoxicity against human tumor cell lines 95-D and HeLa with IC_(50) values of 27.08 and 20.12μmol/L,respectively.     

铁路轮轨冲击振动模拟与试验

对铁路工程领域普遍存在的轮冲击振动现象进行了理论与试验研究。将车辆模拟为移动的多刚体振动系统,将轨道描述成离散点支承连续梁结构,应用快速数值 发方法编制了ＶＩＣＴ模拟软件,实现了轮轨冲击振动的快速数值模拟。     

制冷系统六阶动态模型及仿真

在建立换热器模型时引入过冷度估计和过热度估计,采用分相区集总参数的方法,通过简化分析提取能够反映制冷系统动态特性的最少状态量,建立了制冷系统六阶动态模型。同时采用Matlab的Simulink仿真工具,比较分析六阶模型数据和实验数据,验证六阶模型的正确性。     

Statefinder Diagnostic in Generalized Chaplygin Gas Model with and Without Viscosity

Statefinder diagnostic is a useful method which can distinguish one dark energy model from the others. In this paper, we apply this method to the GCG model with and without viscosity. It is shown that the evolving trajectory of the viscous GCG model in the s–r diagram is not only quite different from the model without viscosity but also different from other dark energy models.     

长波紫外辐射对Ⅰ型胶原损伤的拉曼光谱研究

应用拉曼光谱技术研究了长波紫外(Ultraviolet-A,UV-A)辐射对Ⅰ型胶原的损伤,检测了Ⅰ型胶原及其经过90min的UV-A辐射后的拉曼光谱,得到了一个较完整的Ⅰ型胶原紫外损伤机制。实验结果表明:90min的UV-A辐射导致Ⅰ型胶原分子内氢键断裂、氢键体系发生变化,肽链的螺旋度减少,逐渐解螺旋,无规卷曲等无序构象增加。此外,UV-A辐射使Ⅰ型胶原分子内脯氨酸的羟基化程度降低。这些变化必然会引起Ⅰ型胶原三螺旋结构的损伤,并导致皮肤光老化过程中组织内胶原纤维的破坏。