Synthesis,Characterization, and Antibacterial Activity of Cross-Linked Chitosan-Glutaraldehyde

This present study deals with synthesis, characterization and antibacterial activity of cross-linked chitosan-glutaraldehyde. Results from this study indicated that cross-linked chitosan-glutaraldehyde markedly inhibited the growth of antibiotic-resistant Burkholderia cepacia complex regardless of bacterial species and incubation time while bacterial growth was unaffected by solid chitosan. Furthermore, high temperature treated cross-linked chitosan-glutaraldehyde showed strong antibacterial activity against the selected strain 0901 although the inhibitory effects varied with different temperatures. In addition, physical-chemical and structural characterization revealed that the cross-linking of chitosan with glutaraldehyde resulted in a rougher surface morphology, a characteristic Fourier transform infrared (FTIR) band at 1559 cm⁻¹, a specific X-ray diffraction peak centered at 2θ = 15°, a lower contents of carbon, hydrogen and nitrogen, and a higher stability of glucose units compared to chitosan based on scanning electron microscopic observation, FTIR spectra, X-ray diffraction pattern, as well as elemental and thermo gravimetric analysis. Overall, this study indicated that cross-linked chitosan-glutaraldehyde is promising to be developed as a new antibacterial drug.     

Effects of pre-slaughter nutritional condition on intramuscular collagen solubility, pyridinoline cross-links and meat tenderness in aged goats

Effects of preslaughter nutritional condition on intramuscular collagen characteristics were studied, in order to clarify the potential of intensive feeding to aged animals in improving meat tenderness. Ten castrated male goats were assigned into one of two groups: one group was allowed ad libitum access to a concentrate diet (total digestible nutrients 70%, crude protein 15%) and Italian ryegrass hay (ADLIB‐group), and the other group was fed a restricted amount of their diet (concentrate diet 0.5% of bodyweight/day; hay 1.5% of bodyweight/day) to maintain their bodyweight (MAIN‐group). After 3 months of the experimental period, goats were slaughtered and meat samples were obtained immediately. Goats in ADLIB‐group had lower total and insoluble collagen concentrations, higher fat concentrations and collagen solubility than those in MAIN‐group, but soluble collagen concentrations of muscles were similar for both groups. Goats in ADLIB‐group had lower pyridinoline concentrations than those in MAIN‐group, in all muscles, but the differences of pyridinoline concentration between the groups were not statistically significant. Warner‐Bratzler shear force values of Longissimus and Biceps femoris muscles were lower in ADLIB‐group than in MAIN‐group. The increase of meat tenderness by preslaughter intensive feeding seemed to be associated with the increase in intramuscular fat deposition and high collagen solubility, and pyridinoline cross‐link appeared to be one of the factors related to collagen solubility.     

Mechanical properties of outer layers from near-isogenic lines of common wheat differing in hardness

The mechanical properties of the combined outer layers from near-isogenic wheats differing by hardness were determined. Results from traction tests showed significant differences between the isogenic lines, outer layers from grains of the soft type showing higher extensibility. Determination of the mechanical properties of the corresponding component tissues revealed significant differences between the isolated tissues from soft or hard wheat grains. It also allowed analysis of their respective contribution to the properties of the combined peripheral tissues using a simulation of their rupture as unseparated tissues. According to the results, if the component layers displayed similar maximum lineic force to rupture, the rupture of combined outer layers occurs when the least extensible individual tissue breaks. The major cell wall biochemical components of the combined outer layers and of their component tissues were analysed. The phenolic acid composition of soft wheat pericarp contained more ferulic acid in either monomeric or polymeric forms than the pericarp from hard wheat. Arabinoxylans in walls of the soft wheat pericarp appeared 1.6 times more cross-linked by ferulic acid dehydrodimers than walls of hard wheat. These differences in arabinoxylan cross-linking may explain the observed differences in pericarp mechanical properties.     

氮磷共掺杂生物质多孔碳的绿色合成及其在锂硫电池中的应用

针对多孔碳材料的合成依赖于强腐蚀性造孔剂和额外杂原子化合物,存在碳产率低、制备成本高的问题,该研究提出通过交联作用和原位掺杂策略绿色制备一种高产量、官能团丰富、氮磷共掺杂的生物质多孔碳,再通过物理复合制得碳硫复合材料用作锂硫电池正极。研究结果表明,植酸与烟梗表面官能团的强交联作用有利于形成多孔碳。同时,植酸富含碳和磷元素,可对多孔碳材料进行碳包覆和磷掺杂双重改性,进而提高碳产率,改善材料的导电性,增强材料对活性物质硫的吸附固定效果,加快充放电过程中电子的迁移转化。当植酸用量为20m L时,所制复合材料在0.1C倍率下的放电容量高达1 211 m Ah/g;在1C倍率下循环300圈仍保持为885 m Ah/g,每圈容量衰减率仅为0.029%,表现出优异的循环稳定性。