Effects of wet-spinning conditions on structures,mechanical and electrical properties of multi-walled carbon nanotube composite fibers

A series of composite fibers composed of multi-walled carbon nanotube (MWCNT) and poly(vinyl alcohol) (PVA) are prepared by varying co-flowing wet-spinning conditions such as spinning geometry and PVA concentration, which affect aligning shear stress for MWCNTs during the wet-spinning. Then, structural features, mechanical and electrical performances of MWCNT/PVA composite fibers are investigated as a function of the aligning shear stress of the wet-spinning process. SEM images of the composite fibers exhibit that MWCNTs are wetted effectively with PVA chains. Polarized Raman spectra confirm that the alignment of MWCNTs is enhanced along the composite fiber axis with increasing the aligning shear stress of the spinning process. Accordingly, initial moduli and tensile strengths of the composite fibers are significantly increased with the increment of the aligning shear stress. In addition, it is found that electrical conductivities of MWCNT/PVA composite fibers increase slightly with the aligning shear stress, which is associated with the formation of efficient electrical conduction paths caused by well-aligned MWCNTs along the composite fiber axis.     

The exceptional low temperature flexibility of polyurethane copolymer grafted with dimethylphenyl group

The grafted 3,5-dimethylphenyl group remarkably improved the low temperature flexibility of a polyurethane (PU) copolymer. The rigid and blunt shape of 3,5-dimethylphenyl was designed to interrupt molecular interactions and to disturb the close contact between PU chains and, thus, to improve the flexibility at extremely low temperature, while maintaining high and reproducible tensile and shape memory properties at ambient temperature. The effect of the 3,5-dimethylphenyl group on the flexibility of PU was tested at −30 °C together with a linear PU, and the reason for the exceptional flexibility at low temperature is discussed.     

Current status of genetic transformation technology developed in cucumber(Cucumis sativus L.)

Genetic transformation is an important technique for functional genomics study and genetic improvement of plants. Until now, Agrobacterium-mediated transformation methods using cotyledon as explants has been the major approach for cucumber, and its frequency has been up to 23%. For example, significantly enhancement of the transformation efficiency of this plant species was achieved from the cotyledon explants of the cultivar Poinsett 76 infected by Agrobacterium strains EHA105 with efficient positive selection system in lots of experiments. This review is to summarize some key factors influencing cucumber regeneration and genetic transformation, including target genes, selection systems and the ways of transgene introduction, and then to put forward some strategies for the increasing of cucumber transformation efficiency. In the future, it is high possible for cucumber to be potential bioreactor to produce vaccine and biomaterials for human beings.     

Coincidence of virulence shifts and population genetic changes of Pseudoperonospora cubensis in the Czech Republic

Pseudoperonospora cubensis is an oomycete pathogen causing downy mildew disease on a variety of Cucurbitaceae, and has recently re‐emerged as a destructive disease on crops in this family, mainly on cucumber and squash. Multilocus sequence analysis (MLSA) of four mitochondrial and two nuclear DNA regions was used to detect changes in the genetic structure of P. cubensis populations occurring in the Czech Republic that might be associated with recently reported shifts in virulence. The analysed sample set contains 67 P. cubensis isolates collected from 1995 to 2012 in the Czech Republic and some other European countries. Sequence analyses revealed differences and changes in the genetic backgrounds of P. cubensis isolates. While all isolates sampled before 2009 exhibited the genotype of the subspecies of Clade II and were collected from cucumber, all samples collected from other hosts belonged to Clade I (P. cubensis sensu stricto) or were sampled from 2009 onwards. In addition, 67·16% of all post‐2009 isolates from Clade II had two heterozygous positions in their nrITS sequence, which suggests sexual reproduction and/or a mutational origin. Thus, the results indicate that, apart from the rise in prevalence of Clade I, the change in the genetic structure of P. cubensis populations may be linked with a hybridization or, less likely, a mutation event that rendered strains able to infect a broader spectrum of host species.     

Biomedical and Clinical Importance of Mussel-Inspired Polymers and Materials

The substance secreted by mussels, also known as nature’s glue, is a type of liquid protein that hardens rapidly into a solid water-resistant adhesive material. While in seawater or saline conditions, mussels can adhere to all types of surfaces, sustaining its bonds via mussel adhesive proteins (MAPs), a group of proteins containing 3,4-dihydroxyphenylalanine (DOPA) and catecholic amino acid. Several aspects of this adhesion process have inspired the development of various types of synthetic materials for biomedical applications. Further, there is an urgent need to utilize biologically inspired strategies to develop new biocompatible materials for medical applications. Consequently, many researchers have recently reported bio-inspired techniques and materials that show results similar to or better than those shown by MAPs for a range of medical applications. However, the susceptibility to oxidation of 3,4-dihydroxyphenylalanine poses major challenges with regard to the practical translation of mussel adhesion. In this review, various strategies are discussed to provide an option for DOPA/metal ion chelation and to compensate for the limitations imposed by facile 3,4-dihydroxyphenylalanine autoxidation. We discuss the anti-proliferative, anti-inflammatory, anti-microbial activity, and adhesive behaviors of mussel bio-products and mussel-inspired materials (MIMs) that make them attractive for synthetic adaptation. The development of biologically inspired adhesive interfaces, bioactive mussel products, MIMs, and arising areas of research leading to biomedical applications are considered in this review.     

Suppression of proinflammatory cytokine production by specific metabolites of Lactobacillus plantarum 10hk2 via inhibiting NF-κB and p38 MAPK expressions

The objective of this study was to evaluate the immunomodulatory effects of specific bacterial metabolites of Lactobacillus plantarum 10hk2 to induce anti-inflammatory mediators in cell cultures of the murine macrophage cell line, RAW 264.7. The effects of the extracellular metabolites of this bacterial strain were examined by dividing them into protein and polysaccharide fractions. A specific protein fraction (8.7 kDa) was found to be a strong IL-10 inducer in LPS-stimulated RAW 264.7 cells and suppressed LPS-induced NF-κB induction and inhibited LPS-induced phosphorylation of I-κB and p38 MAPK. To the best of our knowledge, this was the first study that investigated the anti-inflammatory effects of an extracellular peptide derived from lactic acid bacteria. In addition, we characterized the inhibitory mode of this molecule in the induction of proinflammatory cytokines. Based on the findings presented in this study, this molecule holds promise for use as an agent to modulate inflammation related diseases.     

利用AFLP构建大白菜高密度遗传连锁图谱

以大白菜根肿病抗性材料CR Shinki DH系和感病性材料大白菜自交系94 SK杂交F2的138个单株作为构建遗传图谱的群体。利用AFLP技术通过45对引物筛选共获得835个AFLP标记,应用其中608个AFLP标记和6个与抗根肿病基因CRb紧密连锁的AFLP标记转化成的SCAR标记构建了一张包含556个标记位点、10个连锁群、覆盖基因组长度为795 cM的连锁图谱。该图谱中每个连锁群上的标记数在10~83个之间,平均图距在0.86~4.34 cM之间,连锁群长度在43.4~120.9 cM之间。CRb基因定位于第3连锁群9 cM的范围内。     

Effect of fruit-load on the growth,absorption, and partitioning of inorganic nutrients in young ‘Fuyu’ persimmon trees

Tree growth and the increase in inorganic nutrients during a growing season were studied in 3-year-old, container-grown ‘Fuyu’ persimmon trees with different levels of fruit-load. Fruit-load was varied by adjusting the leaf–fruit ratio to 10, 20, 30, and 60 on July 5. Some trees were completely defruited. The whole trees were harvested on November 5 of that year, and increases in dry weight and inorganic elements in different tree parts during the season were measured. A lower leaf–fruit ratio resulted in a higher yield but also decreased fruit weight, soluble solids, and fruit color. Dry weight of the aerial woods and root increased significantly with a greater ratio. However, total dry weight including the fruits was higher in the lower ratio trees than in the higher ratio trees; the weight of a tree that maintained the ratio of 10 was 35% higher than a tree without fruit. Fruits accounted for 62% of total dry weight when the ratio was 10 and 27% when the ratio was 60. The leaf–fruit ratio did not significantly alter the total increase in P, K, Ca, and Mg content. N tended to decrease with an increasing leaf–fruit ratio. Of the total increases of N, P, and K during the season, the fruits accounted for 30%, 50%, and 54% at the ratio of 20, respectively, and the percentages increased to 44, 81, and 74 at the ratio of 10. The inorganic element content in the aerial woods and root tended to increase with greater ratios, especially in the root. When trees were defruited, N and K increases in the root accounted for 44% and 35% of the total increase, respectively. These results indicated that persimmon orchard fertilization programs with different fruit-load levels should accommodate the proportion of nutrients partitioned to fruits that are removed permanently from the tree.     

Rapid selection of catechin-rich tea trees (Camellia sinensis) by a colorimetric method

A rapid and efficient colorimetric method based on the use of Fast Blue B-salt (FBB) was established to select catechin-rich tea trees (Camellia sinensis L.). The catechin levels measured by the colorimetric method under optimized reaction conditions correlated closely with estimations by high-performance liquid chromatography (HPLC) analysis. The FBB colorimetric method was successfully used to classify 160 tea trees on the basis of their catechin contents into rich and poor lines. HPLC analysis of the FBB-selected tea tree extracts showed them to contain (−)-epigallocatechin 186 mg/g in tea tree line HR-29, (−)-epicatechin 43.7 mg/g in HR-82, (−)-epigallocatechin gallate 4.32 mg/g in HR-29, and (−)-epicatechin gallate 0.22 mg/g in HR-52. Classification of tea trees from the Hadong region into catechin-rich and -poor trees was independent of the growing season. Thus the FBB colorimetric method could find application as a reliable tool in screening and selection of tea trees on the basis of their catechin content.