Comparative effectiveness of two alkylammonium compounds as wood preservatives

This study describes a laboratory evaluation of the efficacy of two alkylammonium compounds [didecyldimethylammonium tetrafluoroborate (DBF) and didecyldimethylammonium chloride (DDAC)] when applied via vacuum impregnation or superficial treatment. Treated wood specimens were tested for their termite and microbial resistance under controlled laboratory conditions. The higher chemical retentions were needed to suppress the feeding by Coptotermes formosanus ≦3% mass loss in the multichoice test than in the no-choice test. The DBF and DDAC retention levels necessary to meet the performance requirement ≦3% mass loss after 12-week fungal exposure varied with wood species. The retention level of 3 kg/m³ for DBF and DDAC was generally high to keep the nondurable wood species free of decay. Although there was no difference between DBF and DDAC in the efficacy against decay and termite attack, the former slightly outperformed the latter as an antimold and antisapstain agent.     

Microbial Composition before and after Conservation of Grass-Dominated Haylage Harvested Early,Middle, and Late in the Season

Haylage for horses is often harvested in late plant maturity, which could be associated with an increased risk of impaired hygienic quality in the forage and short aerobic storage stability after bale opening, but knowledge in this area is scant. An experiment was conducted in which the microbial composition was analyzed before and after conservation of primary growth haylage harvested early (June), middle (July), and late (August) in the season during 1 year. The counts of yeast, enterobacteria, and lactic acid bacteria (LAB) in preconserved herbage increased with the advancing harvest time (P ≤ .02). After conservation, the August haylage had increased counts of enterobacteria (log 4.3 colony-forming unit [CFU]/g) and LAB (log 6.5 CFU/g), compared with the June and July haylage (log ≤1.7 CFU/g for enterobacteria and ≤5.7 CFU/g for LAB, P < .001). The yeast counts were the lowest in the June haylage (log 5.0 CFU/g) compared with the July and August haylage (log ≥6.3 CFU/g, P < .001). After conservation, the mold counts were lower in the June haylage and greater in the August haylage (P = .01). In the preconserved herbage, Cladosporium cladosporioides was the most common mold species in June but Fusarium poae was in July, and Mucor fragilis in August. After conservation, Penicillium carneum was the only species found in the June haylage, with M. circinelloides most frequently found in the July haylage and M. hiemalis and M. circinelloides found at similar frequencies in the August haylage. An advanced harvest time resulted in greater counts of enterobacteria, yeast, and LAB and an increased number of mold species in the conserved haylage. The aerobic storage stability of the opened haylage bales measured by temperature was similar among the harvests.     

进口小麦麸皮霉菌总数不确定度的评定

以测定进口哈萨克斯坦小麦麸皮中霉菌总数为例,建立了数学模型,计算出霉菌总数测量扩展不确定度为0．2810。由于霉菌总数各批之间测量结果散发极大,因此,哈萨克斯坦进口小麦麸皮霉菌总数测量结果的不确定度提供95％的置信概率,取值区间为2．3×10^2≤x≤8．4×10^2。     

大型薄壳制件真空辅助树脂传递模塑工艺充模方案仿真分析及优化

针对大型树脂基复合材料制件不适于用实验试错法进行充模方案设计的问题,在分析树脂流动规律的基础上将大型薄壳件的求解区域分解,仿真分析了不同充模方案下树脂在纤维中的流动行为和模腔内压力变化,提出在制件填充面积等分处设置流道的方法,选择和优化大型薄壳制件的充模方案。结果表明:①对于不便进行实验试错法进行真空辅助树脂传递模塑(VARTM)工艺充模方案设计的大型薄壳制件,可以采用数值模拟的方式,以达西定律、能量守恒定律等为计算依据,求解压力场和速度场,对比不同仿真方案的充模时间等数据合理安排注胶方式方法,指导VARTM工艺制备大型复合材料制件合理安排注胶方式,提高生产率、减少因树脂浸润不均匀产生的缺陷。②对于大型薄壳类制件,忽略厚度方向尺寸,影响充模时间的主要因素为流道长度和树脂流动距离。选取尽可能长的注胶流道,合理设置流道位置以减少树脂流动的距离;长流道可以增加树脂瞬时注入量、提高较长时间的压力差;而树脂流程越长,树脂前锋处压力损失越大,流速越慢。③试验提出了制件填充面积等分处设置流道的方法。将大型薄壳工艺制件充模面积等分,注胶流道布置在垂直于制件长度方向的面积等分线上,可缩短充模时间并减少制件两端的树脂富集现象。对于较狭长部分可再次进行面积等分设置流道,以免造成树脂流程过长压力流失过多;而对于较宽阔部分不宜设置过多流道以免树脂前锋稳定前互相接触造成制件充模不均匀。     

水稻机械化插秧标准模架育秧技术研究

通过制作模架改变机械插秧育秧方式,既解决了软、硬盘育秧投入成本高,又解决了双膜育秧切块费工,切块成型标准难掌握、边角碎料多,种、肥、土浪费大的弱点。使水稻机械化插秧育秧成本低,投资少,操作简单,管理方便,秧板利用率高。     

The Effect of Harvest Moisture and Bale Wrapping on Forage Quality, Temperature, and Mold in Orchardgrass Hay

Effects of harvest moisture and bale wrapping on forage quality and mold formation in orchardgrass (Dactylis glomerata L.) hay have not been investigated. The objectives of this study were to determine the effects of initial bale moisture and plastic wrapping on temperature, forage quality (protein, fiber components, and digestible energy), and mold formation in large round-baled orchardgrass hay. In all, 40 round bales of mature orchardgrass hay measuring 1.2 × 1.5 m² were baled at three different moisture ranges (eight bales per treatment): 124 to 166 g/kg (low moisture); 180 to 232 g/kg (intermediate moisture); and 259 to 337 g/kg (high moisture). Selected bales within each moisture range were individually wrapped in plastic (16 bales), and temperature sensors were placed in each bale for up to 10 weeks. The lowest (P ≤ .01) maximum temperature and heating degree-day accumulations were observed when initial bale moisture content was 124 g/kg or when hay was wrapped, regardless of initial moisture content. In 2008 and 2009, all wrapped hays resulted in similar forage quality (P ≤ .14) and mold counts (P = .94) compared with 124 g/kg moisture hay. Hay baled at 166 g/kg resulted in fiber (P ≥ .82) and mold (P = .21) components similar to higher moisture bales. Mold counts for hay baled at 166 g/kg and 124 g/kg moisture were 24.8 × 10⁶ and 2.7 × 10⁴ CFU/g, respectively, demonstrating that large round bales are prone to molding at relatively low moisture concentrations. Maintenance of forage quality and reduction in mold growth were achieved by baling dry (124 g/kg moisture) or wrapping round bales of orchardgrass hay up to 337 g/kg moisture.     

Changes in surface properties of tropical wood species exposed to the Indonesian climate in relation to mold colonies

Changes in mold populations and genera on the exposed surfaces of tropical hardwoods — albizia (Paraserianthes falcata), kapur (Dryobalanop lanceolata), mahoni (Switenia macrophylla), nangka (Artocarpus heterophyllus), puspa (Schima wallchii) — were investigated. The wood specimens were exposed to the Indonesian climate for 32 weeks. Properties including mass loss, wettability, mold growth (colony-forming units), and mold genera were evaluated. The change in properties after exposure was significantly affected by the wood species, but there was no clear relation between mass loss and the initial chemical components or between wettability and wood density. The number of mold populations was different by exposure period and wood species, but there was no significant effect of climate conditions, such as rainfall and ultraviolet radiation. Of the genera identified,Aureobasidium, Cladosporium, andPenicillium were dominant molds on the exposed wood surfaces.     

烟草霜霉病检疫病理学特性的研究

 烟草霜霉病孢囊非凡的繁殖能力和独特的对世界不同地理气候区域的高度适应性,是病害广泛传播和迅速发展的关键因素。虽然关于烟草霜霉病的病原学、生物学和病理学方面已经作了广泛的研究,但涉及病原孢囊在检疫病理学方面的某些特性,则迄今工作甚少。本文在系列研究的基础上证明:(1)孢囊萌发活性与接种后的产孢日数密切相关。在可见产孢的第1~2d内,1h后孢囊即开始萌发,4h后萌发率高达83%以上,而在产孢第4~6d后萌发率降为36.1%及29.6%。(2)孢囊的最低萌发温度为2℃,最适温度为14~21℃,最高温度为35℃。(3)高温对孢囊活性的影响,因受热时间而异,短时间30℃或35℃高温后又转入适温对孢囊萌发有抑制作用,但仍有侵染活性。当30℃超过12h或35℃超过8h,则孢囊侵染活性丧失。(4)当叶面饱和湿度期达4h时,可以发生侵染,叶面饱和湿度期越长侵染率越高。(5)在适宜温湿条件下,每悬滴含5~6个孢囊,侵染率可达30%以上,如含单个孢囊,侵染率可达12%。运用以上数据将有利于提高烟草霜霉病风险分析的有效性。     

大球盖菇部分生物学特性研究

对大球盖菇对黑曲霉菌、青霉菌、木霉菌和粘帚霉菌的抗耐性进行研究.结果表明:大球盖菇对黑曲霉菌、木霉菌、粘帚霉菌抗性较强,形成了拮抗线,对青霉菌的忍耐性较强.并对其机理进行了分析.通过矿质元素和葛藤粉对大球盖菇菌丝产量的影响进行了试验,表明矿质元素铁、铜、钼、锌对大球盖菇菌丝体的生长有明显的促进作用,而钴、钒对菌丝的生长作用较少;不同的浓度的葛藤粉对大球盖菇菌丝体的生长有不同的促进作用,其中培养基中葛藤粉浓度为80 g/L时,对大球盖菇菌丝体的生长促进作用达到最大.