Effect of physicochemical structure of natural fiber on transverse thermal conductivity of unidirectional abaca/bamboo fiber composites

To study the effect of the microstructure of natural fiber on the transverse thermal conductivity of unidirectional composite, abaca and bamboo fibers were unidirectionally aligned to fabricate epoxy composites by a resin transfer molding (RTM) technique. The transverse thermal conductivity of these two types of composites was measured in a steady-state platform. X-ray diffractometer and scanning electron microscopy were applied to analyze the microstructure and morphology of both fibers and composites. The results indicated that the transverse thermal conductivity showed two types of tendencies with fiber content increasing: increasing for bamboo fiber composites, and decreasing for abaca fiber composites. The microstructure and theoretical analysis suggest that the lumen structure plays a great role rather than crystal structures and chemical compounds on the transverse thermal conductivity of unidirectional composites, which is useful for further development and design of natural fiber reinforced composites with better thermal insulation property for people’s daily life.     

GROWEST PLUS: A tool for rapid assessment of seasonal growth for environmental planning and assessment

GROWEST PLUS is a software interface, designed to run a new version of the GROWEST plant growth index simulation model, originally developed by Fitzpatrick and Nix in 1970. The GROWEST model was designed to integrate the major climatic determinants of potential plant growth at broad geographic scales, and GROWEST PLUS allows comparisons of current conditions relative to historical variability. Substantive literature demonstrates the robustness, simplicity and application of GROWEST at regional to national scales. This has led the Bureau of Rural Sciences (BRS) to use this tool as one of a suite of analyses and models in the assessment of Exceptional Circumstances drought applications. The advantage of GROWEST is its simplicity. The model synthesises well established biological responses to seasonal trends in climate. It has the advantage of few dimensions, which significantly reduces computational and processing time. GROWEST performs well with the SGS Pasture Model outputs. In fact, GROWEST's performance is encouraging given the level of simplicity in the model. GROWEST, however, trades off some processes that are important at detailed scales in order to be able to run with readily available input variables for regional scale assessments. Unaccounted processes include detailed simulation of soil moisture, soil fertility and differences between phenological responses at the plant species level. GROWEST PLUS was developed by BRS and the Centre for Resource and Environmental Studies at the Australian National University. The most significant feature of GROWEST PLUS is its ability to analyse variability in seasonal growth over time using time-series outputs from the GROWEST model. For this purpose, the GROWEST model was comprehensively upgraded to run on weekly and monthly climate data, in point or grid form, to produce weekly and monthly outputs. This will have benefit in the analyses of specific events such as drought or the characterisation of growing season reliability for natural resource management. This paper demonstrates how users can easily and intuitively run the upgraded GROWEST model through the GROWEST PLUS graphical user interface, utilising ‘real time’ climate data, in point or grid form, to undertake a range of spatial and temporal analyses.     

Characterisation of oil oxidation,fatty acid,carotenoid, squalene and tocopherol components of hazelnut oils obtained from three varieties undergoing oxidation

Hazelnut oils obtained from three varieties of Chinese hybrid hazelnuts (cv. ‘Liaozhen 3 (LZ)’, ‘Pingou 21’ (PG) and ‘Yuzhui’ (YZ)) were used to compare the lipid oxidation characteristics (peroxide value, p-anisidine value and conjugated diene value), fatty acid profiles and major active components (squalene, carotenoids and tocopherols) under oxidation condition at 60 °C for 40 days, in addition, the molecular structure changes in the three hazelnut oils were monitored by Raman spectroscopy. The lipid oxidation of the three hazelnut oils had similar tendencies, and the oxidation rate was slower in the early stage and faster in the later stage. Polyunsaturated fatty acids (PUFAs) tended to decrease mainly due to the decrease in linoleic acid. LZ had higher contents of tocopherol, carotenoids and PUFAs than the other varieties, while YZ owned the highest content of squalene. Tocopherol and carotenoids of the three hazelnut oils showed easy loss, while squalene was relatively stable. Raman spectroscopy can effectively indicate the degree of oxidation and carotenoid levels of hazelnut oil. This study can provide a scientific basis for variety selection in planting and utilisation of active ingredients for the hazelnut industry.     

NUMERICAL SIMULATION OF GAS TURBULENCE ENHANCEMENT BY PARTICLE-WAKE EFFECT

A new turbulence enhancement model was incorporated into the second-order moment two-phase turbulence model and was used to simulate gas-particle flows in swirling chambers and channels with different wall roughness. The results show that compared with the turbulence modification model not accounting for the wake effect,this model,together with the conventional particle source term,gives simulation results in better agreement with the experimental data.     

纳米纤维素发光材料研究进展

纳米纤维素发光材料不仅具有发光基团特有的光物理或光化学性能,还具备纳米纤维素的可生物降解、生物相容、环境友好等特性,拓展了功能化纤维材料的应用领域.根据制备方法,纳米纤维素发光材料可分为三类:纳米纤维素/碳量子点复合发光材料、纤维素发光碳量子点和纳米纤维素/荧光染料复合发光材料.纳米纤维素发光材料具有独特的光学特性及结...     

Mode II interlaminar fracture properties of Moso bamboo

Bamboo is a kind of biological composites reinforced by unidirectional long fiber. Once there exists crack, the propagation of delamination is controlled by the interlaminar fracture toughness instead of by strength. In this paper, the end notched flexure (ENF) beam specimen was used to test the Mode II interlaminar fracture toughness G_IIC along grain of Moso bamboo internode and the fracture surface was analyzed. The results were obtained that the Mode II interlaminar fracture toughness G_IIC calculated by the experiment parameter substitution method was more accurate and the value was 1303.18 J/m² (coefficient of variation = 8.96%) which was about three times higher than the value of Mode I interlaminar fracture toughness; the crack propagation of Mode II interlaminar fracture was mainly self-similar cracking, but the fracture surface was rougher. Ground tissue in the zone of Mode II crack propagation was characterized by hackle shearing deformation. The SEM photos showed that ground tissue separated from fiber along middle lamella under shear stress and as the increasing of the dislocation of upper and lower layer, the thin-walled ground tissue would fracture transversely by tension, while to thick-walled fiber cell, only middle lamella and primary wall were torn then debonded, fragments remained.     

西印度醋栗枝叶提取物的α-葡萄糖苷酶抑制活性及安全性评价

对西印度醋栗(Phyllanthus acidus Skeels)枝叶提取物的α-葡萄糖苷酶抑制活性及安全性进行评价,为该植物的安全食用和药用研发提供参考。采用溶剂回流提取得到西印度醋栗枝叶的全组分样品,然后按照极性大小进一步对全组分进行分组划段,分别得到石油醚、乙酸乙酯和正丁醇组分,以及乙醇洗脱组分和水溶出组分;以半抑制浓度(IC₅₀)为评价指标,比较不同组分的α-葡萄糖苷酶抑制活性。通过经典急毒实验法测定各组分对小鼠的近似最大耐受量(MTD)和半数致死量(LD₅₀),将全组分样品进行连续灌胃20 d评价其亚急性毒性。结果表明,西印度醋栗枝叶各组分对α-葡萄糖苷酶均有一定的抑制能力;全组分的MTD为2.0 g/kg,不同组分样品的毒性大小为乙醇洗脱组分>水溶出组分>石油醚组分>乙酸乙酯组分>正丁醇组分>全组分。主要急性毒性症状是惊跳随后怠动、扭体、呼吸急促等。亚急性毒性试验未见明显毒性反应及病变,表明在口服摄入西印度醋栗全组分2 g/kg/d(相当于干燥枝叶8.6 g/kg)是安全的,具有开发为降血糖、减肥食品...