Study of Characteristics of Soil Animals in Halophilous Plant Communities of \u3ci\u3eLeymus chinensis\u3c/i\u3e Grasslands of Northeast in China

We have researched soil animals in 8 types of halophilous plant communities of Leymus chinensis grasslands of Northeast China to characterise soil animal groups and explain the role and function of soil animals in grassland ecosystems (Richard & Roger, 1998) and provide a scientific basis for research to improve alkaline lands in these grasslands

Structure Mediation and Properties of Poly(l-lactide)/Poly(d-lactide) Blend Fibers

Poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) blend as-spun fibers (50/50, wt.%) were prepared by melt spinning. Structure mediation under temperature and stress and properties of poly(l-lactic acid)/poly(d-lactic acid)(PLLA/PDLA) as-spun fibers were investigated by wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC). The results show that highly oriented stereocomplex (SC) crystals can be formed in PLLA/PDLA blend fibers drawn at 60 °C and annealed at 200 °C. However, at drawn temperature of 80 °C, only lower oriented SC crystals can be formed. For PLLA/PDLA blend fibers drawn twice at 60 °C (PLLA/PDLA-60-2), the crystallinity of SC crystals increases with annealing temperature in the range of 200 to 215 °C, while the degree of orientation decreases slightly. When the annealing temperature is 210 °C, the crystallinity and orientation of SC crystals in PLLA/PDLA-60-2 fibers reach 51% and −0.39, respectively. Moreover, PLLA/PDLA-60-2-210 fibers exhibit excellent heat-resistant property even at 200 °C. The results indicate that the oriented PLLA/PDLA blend fibers with high SC crystals content can be regulated in a short time

Low-molecular weight aliphatic amides as nucleating agents for poly (L-lactic acid): Conformation variation induced crystallization enhancement

a b s t r a c t Two kinds of low molecular weight aliphatic amides, N, N 0 -ethylenebis (12-hydroxystearamide) (EBH) and N, N 0 -ethylenebisstearamide (EBSA), have been selected in present study to mediate the crystallization behavior of poly (L-lactic acid) (PLLA). The results showed that the crystallization rate of PLLA was significantly improved with the addition of EBH and EBSA, and EBH presented a stronger nucleating efficiency. The correlation between the variation of chain conformation during the early stages of isothermal crystallization and the enhancement of crystallization rate for pure PLLA and its mixtures was investigated by time-resolved FTIR. The formation of interchain conformational-ordered structure and intrachain 10 3 helix structure for amide-doped PLLA preceded that for pure PLLA, suggesting a stimulatory nucleating effect of EBH and EBSA. In the case of PLLA/EBH, the interchain interactions of e(COC þ CH 3 ) and eCH 3 groups were faster than the e(CH 3 þCC) intrachain interactions, while the interchain interactions and the intrachain 10 3 helix formation were nearly synchronous for PLLA/EBSA. The hydrogen bond interaction between hydroxyl groups in EBH and the carbonyl groups in PLLA was proposed to be an important factor influencing the conformation variation during isothermal crystallization of PLLA

The first case of pulmonary disease caused by Mycobacterium septicum in China

SummaryMycobacterium septicum is a rapidly growing Mycobacterium (RGM) that rarely causes pulmonary disease globally. We describe a case of M. septicum pulmonary disease, which to our knowledge is the first reported in China. The isolates were identified as M. septicum and were susceptible in vitro to amikacin, ciprofloxacin, ofloxacin, levofloxacin, kanamycin, and sulfamethoxazole

Genetic Diversity of Mycobacterium tuberculosis Isolates from Tibetans in Tibet, China

BACKGROUND: Tuberculosis (TB) is a serious health problem in Tibet where Tibetans are the major ethnic group. Although genotyping of Mycobacterium tuberculosis (M. tuberculosis) isolates is a valuable tool for TB control, our knowledge of population structure of M. tuberculosis circulating in Tibet is limited. METHODOLOGY/PRINCIPAL FINDINGS: In our study, a total of 576 M. tuberculosis isolates from Tibetans in Tibet, China, were analyzed via spoligotyping and 24-locus MIRU-VNTR. The Beijing genotype was the most prevalent family (90.63%, n = 522). Shared-type (ST) 1 was the most dominant genotype (88.89%, n = 512). We found that there was no association between the Beijing genotype and sex, age and treatment status. In this sample collection, 7 of the 24 MIRU-VNTR loci were highly or moderately discriminative according to their Hunter-Gaston discriminatory index. An informative set of 12 loci had similar discriminatory power with 24 loci set. CONCLUSIONS/SIGNIFICANCE: The population structure of M. tuberculosis isolates in Tibetans is homogeneous and dominated by Beijing genotype. The analysis of 24-locus MIRU-VNTR data might be useful to select appropriate VNTR loci for the genotyping of M. tuberculosis

Investigation on Mycobacterium tuberculosis Diversity in China and the Origin of the Beijing Clade

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