Properties of thermoplastic composites with cotton and guayule biomass residues as fiber fillers

This study was conducted to evaluate the suitability of using residual plant fibers from agricultural waste streams as reinforcement in thermoplastic composites. Three groups of plant fibers evaluated included cotton burrs, sticks and linters from cotton gin waste (CGW), guayule whole plant, and guayule bagasse. The plant fibers were characterized for physical (bulk density and particle size distribution) and chemical properties (ash, lignin and cellulose contents). A laboratory experiment was designed with five fiber filler treatments, namely control (oak wood fiber as the filler - OWF), cotton burr and sticks (CBS), CBS with 2% (by weight) second cut linters (CBL), CBS with 30% (by weight) guayule whole plant (CGP), and CBS with 30% (by weight) guayule bagasse (CGB). The composite samples were manufactured with 50% of fiber filler, 40% of virgin high-density polyethylene (HDPE), and 10% other additives by weight. The samples were extruded to approximately 32 × 7 mm cross-sectional profiles, and tested for physico-mechanical properties. The CBS and CBL had considerably lower bulk density than the other fibers. Cotton linters had the highest α-cellulose (66.6%), and lowest hemicellulose (15.8%) and lignin (10.5%) of all fibers tested. Guayule whole plant had the lowest α-cellulose and highest ash content. Both CBS and guayule bagasse contained α-cellulose comparable to OWF, but slightly lower hemicellulose. Evaluation of composite samples made from the five fiber treatments indicated that fibers from cotton gin byproducts and guayule byproducts reduced the specific gravity of the composites significantly. However, the CBS and CBL samples exhibited high water absorption and thickness swelling, but the addition of guayule bagasse reduced both properties to similar levels as the wood fiber. The CGP exhibited significantly lower coefficient of thermal expansion. Composite samples with the five different fiber fillers showed similar hardness and nail holding capacity, yet oak fibers imparted superior strength and modulus under flexure and compression with the exception of the compressive modulus of CGB composites. In general, both cotton ginning and guayule processing byproducts hold great potential as fiber fillers in thermoplastic composites.     

浅析外墙外保温在住宅中的应用

通过实际的工程经验,总结了外墙外保温在节能建筑应用中的利弊,并举例说明了实际工程中保温材料需要的厚度及其它注意事项。     

Formulating low glycaemic index rice flour to be used as a functional ingredient

Amylose and resistant starch (RS) content in rice flour were manipulated. The experiment was conducted using a full factorial design. Rice flour with average amylose content of 20 and RS content of 0.5 g/100 g dry sample was fortified with pure amylose from potato and high RS modified starch to reach the final amylose content of 30, 40 and 50 and RS content of 2, 4 and 6 g/100 g dry sample. The fortified rice flours were examined for their gelatinisation properties, in-vitro enzymatic starch digestion and gel textural properties. It was found that amylose and RS significantly affect all the fortified rice flour properties (p < 0.05). High amylose and RS improved starch digestion properties, reducing the rate of starch digestion and lowering the glycaemic index (GI) values. Amylose had a more pronounced effect on the fortified rice starch properties than RS. In this study, the fortified rice flour which contained amylose and RS of approximately 74 and 9 g/100 g dry sample respectively was used to produce rice noodles. The noodles exhibited low GI values (GI < 55). However, amylose and RS affected the textures of rice noodles providing low tensile strength and break distance (extensibility).     

γ-纳米Al2O3补强耐磨橡胶衬板的性能研究

以γ型纳米Al2O3补强[天然橡胶（NR）/顺丁橡胶（BR）/炭黑]耐磨橡胶衬板,研究纳米Al2O3对橡胶衬板混炼胶的硫化特性和加工性能以及硫化胶的力学性能、耐磨耗性能和耐热分解性能的影响。结果表明,纳米Al2O3适宜的添加质量分数为3％,此时,橡胶衬板混炼胶的焦烧时间和正硫化时间延长、加工安全性改善但不会影响胶料的硫化程度,并具有较好的加工流动性;纳米Al2O3增强的橡胶衬板硫化胶具有更优异的综合力学性能,且其磨耗量降低了46.2％,初始降解温度提高了58 ℃以上,从而使橡胶衬板硫化胶具有良好的耐磨耗性能和热稳定性能。     

压力蒸汽热改性橡胶木的物理力学性能分析

为研究介质压力在木材高温热改性过程中的作用,采用压力蒸汽作为传热介质,于155℃/0.4 MPa,170℃/0.4 MPa,170℃/0.8 MPa处理条件对橡胶木进行热改性,测试热改性材的质量损失率、明度、抗弯强度、抗弯弹性模量等指标,探讨不同处理压力和温度改性橡胶木的物理力学性能变化。结果表明,在压强0.4 MPa条件下,155℃和170℃处理的试材,其各项性能可以达到或接近常压条件下更高温度热改性材的性能。介质压强由0.4 MPa增加至0.8 MPa,炭化橡胶木的质量损失率、颜色变化、抗弯强度损失均增大,说明压强越大,热改性程度越剧烈。介质压强对试材的热改性程度有显著影响,提高蒸汽压力可以在较低温度下加快橡胶木的炭化过程,实现木材的高效热改性处理。     

秦山核电温排水对鱼类分布的影响

根据2010年5月(春季)、2010年9月(夏季)和2009年12月(冬季)秦山核电海域渔业资源调查资料以及秦山核电站温排水扩散数学模拟结果,通过秦山核电温排水海域鱼类季节密度的时空分布、优势种、优势种对鱼类总数量的贡献,探讨并分析了秦山核电海域温排水对鱼类分布的影响。结果显示,春季、夏季和冬季的尾数密度分别为5.55×10~3 ind/km~2、22.10×10~3 ind/km~2和10.52×10~3 ind/km~2,重量密度分别为33.80 kg/km~2、59.06 kg/km~2和66.46 kg/km~2。秦山核电海域渔业资源数量季节变化的规律与其他海域相反,冬季最高,春夏季较低,主要与冬季温排水海域具有暖池效应,形成部分鱼类滞留在此越冬有关。温排水平面分布对鱼类分布有重要的影响。主要表现在夏季温排水区域鱼类密度低于其他水域,冬季相反,鱼群滞留在温排水热羽区域,因而显示出温排水海域有较高的鱼群密度。温排水对不同适温习性鱼类影响不同,暖温种能够适应一定的低温,例如,刀鲚(Coilia ectenes)可以在温排水水域越冬,而对高温有耐受性的棘头梅童鱼(Collichthys lucidus)夏季在温排水水域成为优势种。鱼类优势种的适温性决定着鱼群的分布特征,冬季最重要的优势种为刀鲚,在尾数上的贡献率高达45.02,由于该种在温排水的热羽区域分布密集,形成温排水水域鱼群密度大于周边水域的现象。由于温排水改变了渔场环境,导致新的越冬场的形成,有可能形成新的渔汛,引起当地渔场属性的改变。     

基于三阶段DEA的中国马铃薯主产区生产效率分析

为了解中国马铃薯主产区马铃薯生产技术效率,本文运用DEA三阶段模型对2012年中国14个马铃薯主产省的马铃薯产业进行了排除环境变量和统计噪音影响的技术效率分析。结果表明：马铃薯生产率受到了各地经济发展水平、商品率、受灾率等环境变量和随机变量的影响;在同等环境和运气的条件下,各马铃薯主产省的纯技术效率差异相对较小,均处于较高水平;规模效率差异较大,整体水平不高;规模效率成为了制约马铃薯技术效率的瓶颈。由此得出结论,要提高中国马铃薯生产技术效率应从生产规模和宏观环境2个方面入手。     

中印罗非鱼产品出口竞争力的比较——基于美国市场的分析

为了对中国和印度尼西亚罗非鱼产品在美国市场的出口竞争力进行比较分析,以1994-2014年的相关贸易数据为基础,实证分析了中印两国的产品竞争力。竞争力的评价方法主要包括国际市场占有率、显示性比较优势指数和恒定市场份额模型。结果表明：中国罗非鱼产品对美国出口总额不断增长,增长速度快于印尼,但印尼罗非鱼产品拥有自己的品牌的外销渠道,市场价格较中国高很多。中国罗非鱼逐步占领了美国大部分市场,印尼的市场占有率则相对稳定。中国罗非鱼产品在美国市场上已经逐步由比较劣势转变为比较优势,但印尼在罗非鱼产品出口上更加具有比较优势;从恒定市场份额模型的分析来看,竞争力效应对中国罗非鱼产品在美国市场出口额的增长的贡献率较高,中国罗非鱼产品的竞争力在不断增强,但罗非鱼产品结构的合理化程度以及在本国出口增长中的贡献率仍低于印尼。     

The Possibilities of Bioenergy Production from Whey

The wastes and the by-products of food industrial technologies are suitable for bioenergy generating because of the high organic matter content. Anaerobic digestion is the eldest technology for waste stabilization and however by controlled decomposition a high value and marketable energy source can be produced. Whey is normally used as a component of dairy products or as an additive for food product. In our work we focused on another utilization method： biogas generating from membrane separated fractions i.e.： permeate and concentrate of whey. The effect of the pH, thermal, microwave pre-treatment and their combinations on the biogas yield were investigated. Our results showed that the applied pre-treatments had significant effect on biogas production. In consequence of the hydrolysis of large molecules the biodegradability of the pre-treated whey fractions was enhanced, therefore the biogas and methane production yield increased significantly.     

冬灌对农牧交错带人工草地越冬期土壤水热状况的影响

通过2005~2007年2个越冬期的田间试验,利用烘干法和时域反射仪测定的土壤总含水量和液态含水量,土壤温度探头测定土壤温度,结合气象资料,分析了处于华北农牧交错带的坝上地区冬灌对越冬期土壤水热动态状况的影响机制,进一步分析了冬灌对土壤水热状况的作用。结果表明,冬灌使土壤入冬时冻结较慢,入春时融化也较慢;冬灌可以缓冲土壤温度的剧烈变化,入冬时使土壤温度降低较慢,入春时使土壤温度的升高也较慢,显著提高表层土壤在入冬和越冬期的温度,有利于牧草的越冬;整个越冬期各处理的土壤总贮水量变化微弱,冬灌的土壤剖面水分优势可以持续到第二年作物返青。