A hevein-like protein and a class I chitinase with antifungal activity from leaves of the paper mulberry

Paper mulberry (Broussonetia papyrifera, syn. Morus papyrifera L.) is a Chinese traditional medicine and its low‐molecular‐weight extracts are reported to have antifungal activity. In this study, two proteins (PMAPI and PMAPII) with activity against Trichoderma viride were obtained from paper mulberry leaves with a fast protein liquid chromatography (FPLC) unit. The purification protocol employed (NH₄)₂SO₄ precipitation, ion‐exchange chromatography and hydrophobic‐interaction chromatography on FPLC. Molecular masses were 18,798 Da for PMAPI, and 31,178 Da for PMAPII determined by Matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry. Peptide mapping fingerprint analysis showed that PMAPI has no peptides similar to PMAPII. N‐terminal amino acid sequencing revealed that PMAPI is a hevein‐like protein, and PMAPII is a class I chitinase. They both had a half‐maximal inhibitory concentration (IC50) of 0.1 µg/µL against T. viride. This is the first report of high‐molecular‐weight extracts with antifungal activity from paper mulberry. Copyright © 2011 John Wiley & Sons, Ltd.     

I型和II型结构气体水合物的记忆效应

利用水合物二次生成实验装置, 采用“定容法”对I型(甲烷、二氧化碳)和II型(丙烷)结构气体水合物的二次生成进行了实验, 研究了不同结构水合物(I型、II型)彼此间的记忆效应, 发现水合物生成过程存在明显的诱导期, I型结构水合物间在二次生成过程中存在着记忆效应. I型与II型结构水合物之间在相互二次生成过程中存在着显著的记忆效应.     

High throughput identification of components from traditional Chinese medicine herbs by utilizing graphene or graphene oxide as MALDI-TOF-MS matrix

In this work, graphene or graphene oxide was utilized, for the first time, to identify small molecular components from traditional Chinese medicine (TCM) herbs, by acting as matrix of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Due to the large surface area of graphene or graphene oxide, the analytes were trapped tightly to the matrix, which avoids the contamination of the ion source and vacuum system. Besides, their excellent electronic, thermal and mechanical properties make them desired matrices for MALDI-TOF-MS. Stable analysis was achieved with no background inference even at the concentration of 100 nM. Moreover, the limit of detection (LOD) could be greatly lowered by utilizing graphene or graphene oxide as a pre-enrichment adsorbent. In summary, the promoted MALDI-TOF-MS methodology was demonstrated to be simple, sensitive, fast, cost effective and, most importantly, high throughput.     

In-source fragmentation and accurate mass analysis of multiclass flavonoid conjugates by electrospray ionization time-of-flight mass spectrometry

In-source collision-induced dissociation (CID) fragmentation features of multiclass flavonoid glycoconjugates were examined using liquid chromatography electrospray time-of-flight mass spectrometry. Systematic experiments were performed to search for optimal conditions for in-source fragmentation in both positive and negative ion modes. The objective of the study was to attain uniformly appropriate conditions for a wide range of analytes independently of the aglycone, the attached sugar part and the type of bond between the aglycone and the glycan moieties (O- or C-glycosides). Studied substances included representatives of flavonols, flavones, flavanones and anthocyanins and, regarding their glycan parts, mono-, di- and triglycosides with varying distribution of carbohydrate moieties (di-O-glycosides, O-diglycosides, O,C-diglycosides). The breakdown properties of the analytes along with the abundances of the characteristic diagnostic ions required for structural elucidation of complex flavonoid derivatives were evaluated. An optimized value was found for the instrument parameter (fragmentor voltage) affecting the in-source CID fragmentation of the analytes [230 V (ESI+) and 330 V (ESI-)]. Thus, appropriate performance in terms of both highly sensitive full-scan acquisition and fragmentation information was obtained for all the investigated flavonoids. In addition, singularities in the abundance of selected diagnostic ions (e.g. Y(0), Y(1) and Y*) due to variations in the interglycosidic linkage (rutinoside-neohesperidoside) in the glycan part were found and are also evaluated and discussed in detail. The combination of in-source CID fragmentation with high mass accuracy MS detection establishes a working basis for the development of versatile and useful LC-MS methods for wide-scope screening, non-targeted detection and tentative identification of flavonoid derivatives.     

Large time behavior of solutions to a degenerate parabolic equation not in divergence form

In this paper, we investigate positive solutions of the degenerate parabolic equation not in divergence form: ut=upΔu+auq−bur, subject to the null Dirichlet boundary condition. We at first discuss the existence and nonexistence of global solutions to the problem, and then study the large time behavior for the global solutions. When the positive source dominates the model, we prove that the global solutions uniformly tend to the positive steady state of the problem as t→∞. In particular, we establish the uniform asymptotic profiles for the decay solutions when the problem is governed by the nonlinear diffusion or absorption.     

Life span and a new critical exponent for a doubly degenerate parabolic equation with slow decay initial values

In this paper, we investigate the behavior of the positive solution of the following Cauchy problem

ut−div(|∇um^|p−2∇um)=uq     

Fractional normal inverse Gaussian diffusion

A fractional normal inverse Gaussian (FNIG) process is a fractional Brownian motion subordinated to an inverse Gaussian process. This paper shows how the FNIG process emerges naturally as the limit of a random walk with correlated jumps separated by i.i.d. waiting times. Similarly, we show that the NIG process, a Brownian motion subordinated to an inverse Gaussian process, is the limit of a random walk with uncorrelated jumps separated by i.i.d. waiting times. The FNIG process is also derived as the limit of a fractional ARIMA processes. Finally, the NIG densities are shown to solve the relativistic diffusion equation from statistical physics.     

Ruin probability and joint distributions of some actuarial random vectors in the compound pascal model

The compound negative binomial model,introduced in this paper,is a discrete time version.We discuss the Markov properties of the surplus process,and study the ruin probability and the joint distributions of actuarial random vectors in this model.By the strong Markov property and the mass function of a defective renewal sequence,we obtain the explicit expressions of the ruin probability,the finite-horizon ruin probability,the joint distributions of T,U(T-1),|U(T)| and 0≤inn相似文献   

Energy decay estimates for the dissipative wave equation with space–time dependent potential

We study the asymptotic behavior of solutions of dissipative wave equations with space–time‐dependent potential. When the potential is only time‐dependent, Fourier analysis is a useful tool to derive sharp decay estimates for solutions. When the potential is only space‐dependent, a powerful technique has been developed by Todorova and Yordanov to capture the exact decay of solutions. The presence of a space–time‐dependent potential, as in our case, requires modifications of this technique. We find the energy decay and decay of the L² norm of solutions in the case of space–time‐dependent potential. Copyright © 2010 John Wiley & Sons, Ltd.