Averaging approximation to singularly perturbed nonlinear stochastic wave equations

An averaging method is applied to derive effective approximation to the following singularly perturbed nonlinear stochastic damped wave equation \nu u_{tt}+u_t=\D u+f(u)+\nu^\alpha\dot{W} on an open bounded domain $D\subset\R^n$\,, $1\leq n\leq 3$\,. Here $\nu>0$ is a small parameter characterising the singular perturbation, and $\nu^\alpha$\,, $0\leq \alpha\leq 1/2$\,, parametrises the strength of the noise. Some scaling transformations and the martingale representation theorem yield the following effective approximation for small $\nu$, u_t=\D u+f(u)+\nu^\alpha\dot{W} to an error of \ord{\nu^\alpha}\,.Comment: 16 pages. Submitte

One country, many industries: Heterogeneity of Chinese OFDI motivations at meso level

Research on the stimulants for Chinese Foreign Direct Investment (FDI) is extensive. However most analysis incorporates theoretical models based on the Institution-Based View or, to a lesser extent, the Resource-Based View (RBV). These highlight the importance of the macro (country) and micro (firm) level, while largely ignoring the meso (industry) level. In addition, although investments are known to have several different motivations, stimulated by quite different factors, analysis tends to focus on aggregate FDI flows. We contribute to the literature by proposing an ‘industry-based view’ of FDI which takes account of heterogeneity across industries and FDI motivation. We apply this framework to Chinese OFDI in Europe, differentiating both in terms of investment motivations and sectoral characteristics at (meso) industry level and at (micro) firm level, in home and host countries. Using logistic and multinomial logistic models, our analysis confirms that different types of Chinese FDI (in terms of motivation) are stimulated by different industry-level characteristics in both home and host countries

Doping dependent evolution of magnetism and superconductivity in Eu1-xKxFe2As2 (x = 0-1) and temperature dependence of lower critical field Hc1

We have synthesized the polycrystalline samples of Eu1-xKxFe2As2 (x = 0-1) and carried out systematic characterization using x-ray diffraction, ac & dc magnetic susceptibility, and electrical resistivity measurements. We have seen a clear signature of the coexistence of superconducting transition (Tc = 5.5 K) with SDW ordering in our under doped sample viz. x = 0.15. The spin density wave transition observed in EuFe2As2 get completely suppressed at x = 0.3 and superconductivity arises below 20 K. Superconducting transition temperature Tc increases with increase in K content and a maximum Tc = 33 K is reached for x = 0.5, beyond which it decreases again. The doping dependent T(x) phase diagram is extracted from the magnetic and electrical transport data. It is found that magnetic ordering of Eu-moments coexists with superconductivity up to x = 0.6. The isothermal magnetization data taken at 2 K for the doped samples suggest 2+ valence states of Eu ions. We also present the temperature dependence of the lower critical field Hc1 of superconducting polycrystalline samples. The value of Hc1(0) obtained for x = 0.3, 0.5, and 0.7 after taking the demagnetization factor into account is 248, 385, and 250 Oe, respectively. The London penetration depth {\lambda}(T) calculated from the lower critical field does not show exponential behaviour at low temperature, as would be expected for a fully gapped clean s-wave superconductor. In contrast, it shows a T2 power-law feature down to T = 0.4 Tc, as observed in Ba1-xKxFe2As2 and BaFe2-xCoxAs2.Comment: 17 pages, 10 figure

Cloning and characterization of peptidylprolyl isomerase B in the silkworm, Bombyx mori

Peptidylprolyl isomerases (PPIases) play essential roles in protein folding and are implicated in immune response and cell cycle control. Our previous proteomic analysis indicated that Bombyx mori PPIases may be involved in anti- Bombyx mori nucleopolyhedrovirus (BmNPV) response. To help investigate this mechanism, we cloned a B. mori PPIase gene PPIB and characterized it by bioinformatic and experimental analysis. We found that the B. mori PPIB gene contains 4 exons and its cDNA is about of618 bp, encoding a protein of 205 amino acid residues (21474.41 Da) with an isoelectric point of 8.05. PPIB contains conserved and unique cyclophilin domain and belongs to cyclophilin superfamily. Its transcription could be detected by PCR in all the B. mori tissue samples, which is consistent withnormal PPIase expression pattern and their essential roles. It is localized in cytoplasm revealed by fluorescence microscopy. We also successfully expressed this protein in E. coli and characterized it by SDS-PAGE and Mass Spectrometry. The cloned DNA sequence was submitted to GenBank (EU583493)

Spores of Clostridium engineered for clinical efficacy and safety cause regression and cure of tumors in vivo.

Spores of some species of the strictly anaerobic bacteria Clostridium naturally target and partially lyse the hypoxic cores of tumors, which tend to be refractory to conventional therapies. The anti-tumor effect can be augmented by engineering strains to convert a non-toxic prodrug into a cytotoxic drug specifically at the tumor site by expressing a prodrug-converting enzyme (PCE). Safe doses of the favored prodrug CB1954 lead to peak concentrations of 6.3 μM in patient sera, but at these concentration(s) known nitroreductase (NTR) PCEs for this prodrug show low activity. Furthermore, efficacious and safe Clostridium strains that stably express a PCE have not been reported. Here we identify a novel nitroreductase from Neisseria meningitidis, NmeNTR, which is able to activate CB1954 at clinically-achievable serum concentrations. An NmeNTR expression cassette, which does not contain an antibiotic resistance marker, was stably localized to the chromosome of Clostridium sporogenes using a new integration method, and the strain was disabled for safety and containment by making it a uracil auxotroph. The efficacy of Clostridium-Directed Enzyme Prodrug Therapy (CDEPT) using this system was demonstrated in a mouse xenograft model of human colon carcinoma. Substantial tumor suppression was achieved, and several animals were cured. These encouraging data suggest that the novel enzyme and strain engineering approach represent a promising platform for the clinical development of CDEPT

Antioxidant activity of longan (Dimocarpus longan) barks and leaves

In this paper, the barks and leaves of longan (Dimocarpus longan Lour.) were extracted with 80% methanol. The antioxidant activity and the contents of ellagic acid (EA) in the extracts were investigated. For the evaluation of antioxidant activities, the extracts possess almost the same 2,2- diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and reducing power. Besides, the antioxidant activity was concomitant with the development of the reducing power with high correlation coefficients. The contents of EA in the extracts were 0.91 and 3.723 mg/g dry samples, respectively. After hydrolysis, the EA contents increased almost three and four times. Therefore, the ellagic acid in longan barks and leaves exist mostly in the form of ellagitannins. The research showed that longan barks and leaves not only were excellent sources of free-radical inhibitors, but also had potential use in the production of ellagic acid.Key words: Antioxidant activity, ellagic acid, longan, barks, leaves

A Novel Solid-acid Catalyst Using Sulfonated Crosslinked Chitosan Resin

Sulfonated crosslinked chitosan resins (SCCRs) were prepared by firstly crosslinking chitosan to crosslinked chitosan resins (CCRs) using a reverse emulsion crosslinking method, followed by sulfonating CCRs with concentrated H2SO4 as the sulfonation agent. The properties and application of SCCRs as solid acid catalysts were studied. The acidic sites in SCCRs, including C6–O and C2–N sulfate groups, are all weak acidic sites. SCCRs of higher crosslinking degrees have a higher sulfonation rate of the C6 primary hydroxyl groups, thus more C6–O sulfate groups. High-temperature treatment and TG analysis verified that the crosslinking can improve the thermostability of both SCCR backbone and its acidic groups, and a higher crosslinking degree leads to better thermostability. Catalytic esterification of citric acid with butanol and propionic acid with n-butyl alcohol demonstrated that SCCRs have good catalytic activity and can be repetitively used as efficient solid acid catalysts