Chemical characterization of smoke from the production process of wood-plastic composites

The chemical composition of unpleasant smell, emitted from the production process of wood-plastic composites using Manchurian ash sawdust (Fraxinus mandschurica Rupr.) and polypropylene powder as the raw material, was investigated. Wood sawdust and polypropylene powder were subjected to heat treatment to 290°C during 8 min (the conditions were similar to those employed on an industrial scale). The emitted compounds were collected and analyzed by gas chromatography-mass spectrometry (GC-MS). The analytical r...     

余甘果抗衰老作用的研究

选用果蝇作实验动物，通过余甘原汁、余甘粉和余甘营养液对果蝇寿命影响的研究表明，在一定的浓度范围内，余甘子的３种产品都能延长果蝇寿命，尤其是２５％浓度余甘营养液能使果蝇平均寿命比对照延长１倍以上，从而进一步验证了余甘果的抗衰老作用。     

二灰碎石抵抗冻融破坏作用的研究

针对黑龙江省寒冷的气候特点,对已建公路二灰碎石半刚性基层的使用状况进行调查,分析破坏的原因,并与研究成果进行比较。利用低温实验室模拟自然环境进行冻融循环试验,确定二灰碎石在一定的冻融循环作用下的强度衰减系数,为冻融循环作用下的基层设计提供有一定可靠度的基层强度设计值,保证基层在使用周期内具有一定的冻融耐久性,从而可以提高道路使用质量和延长道路使用寿命,降低维护费用。     

土壤含水量对三种阔叶树苗光合作用的影响

研究了在温室内用盆栽法,其土壤含水量对茶条槭、山梨和山桃三种阔叶树苗光合作用的影响,以及各树种在土壤相对含水量为75.0%时光合作用的日变化.     

粘土路基施工技术

本文主要论述了路基填筑粘土不利因素以及粘土掺灰的机理特点，同时介绍了粘土处理在工程施工中的技术应用。     

Rapid production of high-strength cement-bonded particleboard using gaseous or supercritical carbon dioxide

This study deals with the effects of curing treatment with gaseous and supercritical carbon dioxide on the properties of cement-bonded particleboard (CBP) manufactured by the conventional cold-pressing method. The hydration of cement and the mechanism of improvement were examined using X-ray diffractometry (XRD), thermal gravimetry (TG-DTG), and scanning electron microscopy (SEM) observations. The results are as follows: (1) The curing of cement was accelerated concomitantly with the improvement in mechanical and dimensional properties of CBP significantly by curing with gaseous or supercritical carbon dioxide. (2) Supercritical carbon dioxide curing imparted boards optimal properties at a faster rate than did gaseous curing. (3) Accelerated formation of calcium silicate hydrate and calcium carbonate and the interlocking of those hydration products on the wood surface are potentially the main reasons for the superior strength of carbon dioxide-cured boards.     

Storage of non-dormant seeds of Fraxinus angustifolia Vahl

The effects of drying and storage on the quality of Fraxinus angustifolia non-dormant seeds have been investigated. Mature seeds subjected to a 2-week warm stratification (20 °C) followed by a 2-week cold stratification (3 °C), were exposed to a gentle air stream at room temperature to dry them to 9.5% moisture content. After 4, 8 and 12 months of storage at –3 °C, in hermetically sealed containers, germination tests were conducted in darkness at 30/20 °C and 25/5 °C to evaluate possible changes in seed quality. The results obtained suggest the feasibility of drying non-dormant seeds. In fact, though causing a slight decrease in seed quality, such a process enables storage of ready to sow seeds for at least 12 months without any further loss. The temperature regime of 30/20 °C, prescribed by the International Seed Testing Association (ISTA), was found to be suboptimal for the particular conditions tested in this trial, the 25/5 °C cycle being more stimulating for germination.     

粉煤灰在江苏省公路施工中的应用

本文分析了粉煤灰的化学组成、颗粒组成 ,介绍了粉煤灰在江苏省的应用情况 ,并对粉煤灰的应用进行了综合评价。     

花椒绵粉蚧寄生性天敌的调查研究

1999—2001年在花椒绵粉蚧Phenacoccus azaleae Kuwana发生严重的山西省盂县对该虫的天敌昆虫进行了详细的调查研究，发现绵粉蚧长索跳小蜂Anagyrus shoenherri (Westwood)、蚜虫跳小蜂Syrphophagus aphidivorus(Mayr)、宽缘金小蜂Pachyneuton sp．、长盾拟金小蜂Eunotus sp．和荆腹拟金小蜂(Gastrancistrus sp．等5种寄生性小蜂类天敌昆虫，其中绵粉蚧长索跳小蜂是优势种，它1a发生2代，成虫出现于4月和6月，对蚧虫越冬期的若虫、春天出蛰的雌性若虫、雌成虫及卵均能寄生。在花椒纯林内对产卵期的蚧虫寄生率为8．7％，在花椒与农作物混种的林地，由于经常喷洒杀虫剂，寄生率只有0．56％。根据该小蜂在白蜡绵粉蚧上的高寄生率，提出从蚧虫多年发生区采集寄生蜂，释放到新发生区的建议。     

混凝土挡土墙裂缝原因及防治办法

本文作者通过自己多年的工程施工实践,结合设计与施工中共同存在的问题及注意事项,总 结出了混凝土挡土墙裂缝产生的主要原因及防治方法。