Pattern of parenchyma and canal resin composition in softwoods and hardwoods

There is a general pattern of resin chemistry for parenchyma cells and secretory tissue. In sapwood the parenchyma resin is composed of fats, steryl esters, and occasionally waxes. Secretory tissue (most often resin canals) contains terpenes, terpenoids, and polyisoprenes. Other types of canal resin occur in a few hardwood families. The pattern is valid for softwoods and hardwoods. It has been defined from a comparison of available information on wood chemistry, wood anatomy, and the chemistry of oleoresin exudates from trees. This is a short overview with the most important references of two detailed reports.     

板栗苞单宁纯化的研究

以通常废弃的板栗苞为原料,经过提取得到板栗苞单宁提取物,并对提取物的纯化进行了研究。分别研究了吸附剂的选择、柱前液质量浓度、洗脱剂、蒸馏水的pH值、流速等单因素对单宁得率的影响,并通过正交试验得出了纯化的最佳工艺条件,即:选用大孔树脂D301为吸附剂,丙酮为洗脱液,柱前液质量分数为9%,蒸馏水pH值为7,过柱流速为0.4 L/h。最后,通过稳定性实验对所得工艺条件进行了验证,按此工艺条件纯化后的板栗苞单宁得率在82%以上,单宁质量分数在62%以上。     

Effect of nitrogen addition on DOC leaching and chemical exchanges on canopy leaves in Guangdong Province,China

The impact of nitrogen(N)deposition on dissolved organic carbon(DOC)fractions in throughfall is not well understood.We performed a laboratory experiment and compared DOC leaching from canopy leaves after dipping leaves in pure water(control)and NH4NO3 solution(N-treatment)for 18 h.Net changes of DOC,NH4^+,NO3^-,SO4^2-,K^+,Mg^2+,Ca^2+and H^+contents after dipping leaves were determined by comparing solutions with and without leaves.We recorded no differences of DOC leaching between control and N-treatment,implying that N deposition had minor impacts on canopy DOC production.This confirmed that previous experiments testing the effects of N addition on DOC dynamics without considering the effects of the canopy reaction successfully described the real situation.We also confirmed the previously-reported canopy exchange process in spite of a high background N deposition at our study site.N-treatment significantly increased base cation leaching,especially K^+,and the increase was positively correlated with foliar NH4?retention.Net leaching of H^+and SO4^2-was not affected by the N-treatment.     

Effects of Liquid Crystalline Epoxy Resin on the Properties of Bio-based Cardanol-furfural Resin北大核心CSCD

By using polarized optical microscopy, differential scanning calorimetry, scanning electron microscopy and impact strength measurements,the effects of liquid crystalline on the morphologies, thermal properties and mechanical properties of the composite resins were studied. It was found that the synthesized 4,4-diglycidyloxybiphenyl (BP) and sulfanilamide (SAA) were used to generate novel liquid crystalline (LC) epoxy resins notably. The results revealed that the curing of the cardanol-furfural resins was accelerated and the thermal properties were considerably improved by adding the LC epoxy resins.When the addition of BP-SAA was 50%, the glass transition temperature increased from 60.4 ℃ to 70.2 ℃, and the thermal decomposition temperature increased from 300.3 ℃ to 377.4 ℃, respectively. When the addition of BP-SAA was 30%, the impact strength of the modified resins was 15 kJ/m2 and about three-fold higher than that of the unmodified counterpart. © 2018, Editorial Board of «Chemistry and Industry of Forest Products». All right reserved.     

应对极端天气气候事件的挑战——对加强社会科学与自然科学交流合作的思考

指出了全球气候变化引发严重干旱、冰冻、暴雨等极端天气气候事件的多发,指出了应对极端天气气候事件除自然科学的研究外还应加强社会人文科学的研究,实现多学科的联合,探讨了在减灾防灾时提供人文科学的方法,将灾害的影响和损失降到最低,对学科间加强交流合作进行了思考。     

玉米淀粉改性UF树脂胶合高含水率单板

采用半酯化的玉米淀粉与脲醛树脂(UF)共聚改性,探讨加入量、脲醛树脂的量比、混合比、热压条件等对胶液的黏度、稳定性、固化时间及胶合质量的影响.结果表明:当单板含水率提高到16%～18%时,用改性UF树脂生产的多层胶合板,其物理力学性能指标达到GB/T 9846.1～12-88中Ⅱ类胶合板的要求,并大幅度地降低了胶合板的制造成本.     

广西湿地松松脂化学组成的研究

用气相色谱法测定广西湿地松松脂的化学成分，通过大量的分析数据探讨影响其化学成分变化的气候、地理与环境因素。对比了湿地松松脂与马尾松松脂的成分差异。     

聚氨酯橡胶胀形模设计

在生产中大型制件胀形模,由于材料拉伸变形较大,往往导致制件开裂、起皱等问题.小型制件采用聚氨酯橡胶制造胀形模已得到了应用,以此为基础,对摩托车油箱这种较大零件的胀形模进行改进,用聚氨酯橡胶代替原钢制凸模,很好地解决了零件出现的缺陷,在生产中已获得了成功并投入使用.     

星型环氧乳化剂合成及乳液的性能研究

采用自制星型乳化荆合成水性环氧乳液,考察了乳化剂的结构与环氧乳液稳定性及涂膜性能的关系,优化了乳化荆在制备环氧乳液过程中的主要参数。研究结果表明：聚乙二醇和环氧树脂E-20中环氧基与羟基的物质的量比为1．5：1．0、聚乙二醇的相对分子质量为4000、乳化剂用量为10％时,制备的环氧乳液稳定性高、成膜性能优良。     

Routing protocol of the wireless sensor networks for bridge health monitoring

By analyzing the reason that why the existing routing protocols cannot be applied to the wireless sensor networks for bridge health monitoring, a new routing protocol is proposed. Since the locations of the collecting modules are fixed, the proposed protocol exchanges the routing information between the neighbor nodes by adjusting the exchange cycle according to reliability of the modules. For the low routing security requirement, while to increase the routing efficient, the middle nodes replying the routing requirements with variable thresholds is introduced. In order to make full use of information in route discovering procedure, the backup routes mechanism is adopted. The proposed protocol can efficiently forward data and is suitable for the bridge health monitoring.