Influence of felling season,drying method and within-tree location on the brinell hardness and equilibrium moisture content of wood from 27–35-year-old Betula pendula

The Brinell hardness and equilibrium moisture content (EMC) were measured from thinning-aged silver birch wood. Wood material both from the trees harvested in the first commercial thinning and from trees remaining on site after the thinning was included. The average Brinell hardness was 19.40 MPa. It correlated significantly with the basic density of wood. With respect to the distance from the pith, the Brinell hardness of air-dried wood was higher than that of artificially dried wood. The average EMC of the conditioned (20°C, 65% relative humidity) wood was 12.0%. The EMC of the wood also varied, with the EMC being higher for air-dried wood than for kiln-dried wood. EMC was the highest at a distance of 30–40 mm from the pith, decreasing towards both pith and log surface. Seasonal variation in both the Brinell hardness and the EMC of the wood was found. It was presumed to be a consequence of season-dependent physiological changes in trees.     

Fine-Root Production and Aboveground Development for Loblolly Pine,Silver Maple,and Cottonwood

Fine-root production was studied in recently established loblolly pine (Pinus taeda), silver maple (Acer saccharinum), and cottonwood (Populus deltoides) biomass plantations. Dry weights of fine roots produced in ingrowth cores were recorded from April 2008 to March 2009 to quantify the temporal variation of fine-root production among the species. Similarly, fine-root production was compared to the monthly height and diameter increments, soil temperature, and moisture content. Species showed no significant difference in fine-root production; however, fine-root production varied by month. Fine-root production in September was significantly different from that of December and January combined, February, and May. Loblolly pine produced 49 g m^?2, whereas silver maple and cottonwood produced 37 g m^?2 and 35 g m^?2 of fine roots, respectively, during the study period. Fine-root production was not correlated with height increment, diameter increment, soil temperature, and soil moisture.     

一种淡水鱼头尾与腹背定向装置的研究

本文设计了一种淡水鱼头尾与腹背定向装置,并以鲢鱼为定向对象,根据鲢鱼的摩擦特性,通过理论分析,分别对利用倾斜振动台面实现头尾定向和利用渐变滑道实现腹背定向过程的机理进行了探讨,并采用体重为0.75-1.0kg的新鲜鲢鱼进行了试验研究。理论分析和试验结果均表明,这种定向装置可以实现鲢鱼的头尾和腹背定向。并对影响鱼体鱼体头尾定向因素：进入振动台面的体位、电动机频率、激振力和筛面角,以及影响鱼体腹背定向因素：滑道夹角、电机频率、激振力和滑道倾斜角分别进行了试验研究,得出各因素对定位时间均具有显著的影响,试验中,头尾定向的总定位率达到了97.53%,定向动作可在0.65-3.75s内完成;腹背定位的总定位率达97.2%,定向动作可在0.39-5.03s内完成。     

棉花AFLP银染技术及品种指纹图谱应用初报

本文介绍了一种适合于棉花研究的ＡＦＬＰ银染方法,并利用该方法获得了几个棉花品种的指纹图谱     

纳米级涂层对竹材光泽度的影响

采用TiO2、ZnO、SiO2、AW 4种纳米颗粒和蒸馏水、AR、三聚氰胺树脂、酚醛树脂4种成膜物质组合成16种配方的涂层,对竹材耐光老化涂层的光泽度变化进行试验,结果表明,无机纳米材料为SiO2,成膜物质为三聚氰胺树脂的试样在光老化时光泽度的变化率最小。     

Morpho-physiological and biochemical response of maize (Zea mays L.) plants fertilized with nano-iron (Fe3O4) micronutrient

Nano-sized formulations of micronutrient iron (Fe) were found to substantially alter the growth and metabolism of maize plants. Plants fertilized with the optimal recommended dose of Fe in the nano-form (54 μM) registered an enhancement in morphological features, viz. plant height, biomass (shoot and root), and diminution in antioxidant enzyme activities than the plants fertilized with the sub-optimal dose of Fe in the macroform (salts). However, half of the recommended dosage of Fe (27 μM) in the nano-form positively influenced leaf area and proline content of plants too. This indicated that there is a possibility of reducing the dose of Fe supplement for plants in the nano-form to increase the nutrient use efficiency in a major cereal crop like maize. This may open a new era in plant nutrient management with a scope for improvement in nutrient use efficiency using nano-nutrient formulations.     

不同分子量壳聚糖对白鲢鱼丸货架期品质的影响

将壳聚糖应用于白鲢鱼糜制品的保鲜,通过时白鲢鱼丸货架期的pH值、挥发性盐基总氮、TBA值、过氧化值以及菌落总数的测定,研究了壳聚糖对鱼丸货架期品质的影响.鱼丸中添加1%的壳聚糖成分即可有效抑制其脂质氧化与微生物的生长.壳聚糖对鱼丸的保鲜功能取决于其分子量大小,与高分子量的壳聚糖相比,低分子量的壳聚糖具有更强的抗氧化能力,且30万分子量与1万分子量壳聚糖的混合物具有更强的抗菌能力.     

一种植物病毒检测新方法—纳米上转换荧光技术

随着大豆进口量的日益增加,大豆携带病毒传入我国的风险在不断增大,高效、快速地进行植物病毒检测,防止外来有害生物入侵,是目前各口岸植物检疫工作的重点。本文介绍了一种植物病毒检测的新方法—纳米上转换荧光技术。该技术是一种利用磁性纳米颗粒(magnetic nanoparticles, MNP)进行病毒分离、富集和定位;同时引入上转换荧光(up converting phosphor, UCP)材料作为标记物的免疫检测方法,具有高度的抗干扰性、多元性、稳定性和安全性等特点。     

Effect of Temperature on the Induction of Bud Dormancy in Ecotypes of Betula pubescens and Betula pendula

The purpose of this study was to determine the influence of temperature applied during short day-induced budset on induction of dormancy in six ecotypes of Betula pubescens Ehrh. and two ecotypes of Betula pendula Roth. Seedlings were grown in a phytotron at constant temperatures of 9–21°C under a 12 h photoperiod (SD) during dormancy induction. Induction of dormancy was monitored by following bud flushing and shoot growth after transfer to long photoperiod conditions (24 h) at 18°C. Chilling requirement was studied in seedlings exposed to 10 weeks of SD. In both species induction of bud dormancy developed most rapidly at 15–18°C, and both 9–12°C and 21°C delayed the induction of dormancy. Raising the temperature (from 9 to 21°C) applied during induction of dormancy significantly increased the chilling requirement. These responses were noted for all ecotypes tested, but in general the northern ecotypes entered dormancy more quickly than the southern ones. No such trend was recorded for chilling requirement, although a B. pubescens ecotype from Iceland and another from the coast of northern Norway appeared to require a longer chilling treatment than the other ecotypes. In conclusion, induction and depth of bud dormancy in birch are significantly affected by temperature conditions and these effects may explain some of the annual variation in dormancy and chilling requirement observed in nature.