阔叶材(山杨和速生杨)漂白浆和未漂浆水解降解及其产物性质的研究(英文)

本文研究了木素含量为0.2—1.2％的山杨和速生杨漂白浆和未漂浆的水解降解过程。研究结果表明,该过程与先前已研究过的其它种类的木浆具有相类似的特点,即水解过程存在两个明显的阶段(快速降解阶段和缓慢降解阶段),最终纤维素降解至“极限”聚合度。由不同原料用不同方法制成的不同种类的浆,其水解速度以递减的顺序排列为:山杨浆(漂白浆和未漂浆)→白桦浆→速生杨浆(漂白浆和未漂浆)→针叶材硫酸盐浆→针叶材亚硫酸盐浆(3.7×10~(-4)/分,1.7×10~(-4)/分→1.6×10~(-4)/分→1.3×10~(-4)/分,0.9×10~(-4)/分→1.2×10~(-4)/分,0.8×10~(-4)/分) 水解后纤维索达到“极限”聚合度,后者大小取决于原料种类。山杨硫酸未漂浆分别为206和135;氧碱法山杨浆为160;速生杨硫酸盐未漂浆和漂白浆分别为250和240。水解后试样呈白色粉末状,得率82～85％。试样以其吸水能力为显著特征。未经超声波分散作用的试样,其吸水值比原浆低(从未漂浆90～115％和漂白浆75～95％降至70～80％)。反之,于水中经超声波分散作用后,试样的吸水值急剧增大(山杨微晶纤维素为160％,速生杨微晶纤维素为260％),接近于桦木浆和棉浆微晶纤维素的水平。对原浆纤维和微晶纤维颗粒形状和大小进行了显微观测。测得的数量分布微分曲线表明,在酸水解     

中欧地区的森林培育及其启示

文中简述了中欧的林业发展史，特别对德国森林培育的现状和存在的问题进行了比较详细的分析。根据德国森林培育的历史和经验，提出了对中国林业建设的几点启示。     

低臭氧型负离子雾霾空气净化器设计

降低负离子空气净化器的臭氧排放量,保护人们免受臭氧的伤害,可以在传统净化器的基础上增加紫外线除臭氧和催化剂除臭氧。臭氧很不稳定,吸收254 nm波长的紫外线后,分解为氧气。高效臭氧分解催化剂能在室温下将臭氧分解为氧。普通负离子空气净化器会释放超标的臭氧,其浓度高达205 ppb,而加入除臭氧装置的新型净化器则释放的臭氧很少,使其浓度控制在19 ppb之内。低臭氧型负离子雾霾空气净化器能有效地清除自身产生的臭氧,性能更优,适合在室内使用。     

湖北襄阳市对冷冻动物产品的监管办法

通过分析湖北襄阳市实行的驻场官方兽医、冷库开办方、冷冻产品经营户三级冷冻动物产品监管模式,发现实践中存在缺乏统一性和可追溯性问题,提出了健全规章和追溯体系、统一规范标准的建议。     

山东省外观健康羊群中检出羊边界病病毒

2014年从山东省外观健康的牛羊采集鼻拭子样品共707份,提取其RNA,用流感病毒特异性引物进行RT-PCR检测。对RT-PCR扩增的阳性产物进行序列测定,意外发现其中1份羊拭子样品含有羊边界病病毒,并且该结果得到其他试验验证。结合我国2012年首次在安徽和江苏两地检出该病毒,以及当前我国羊群流通情况,推测该病毒可能在我国有所存在。该调研结果对分析各类RT-PCR检测的假阳性产生原因,有参考意义。并提示RT-PCR检测结果难以作为疫病或感染病诊断的确切依据。其诊断结果有时需要用荧光探针或测序进行进一步鉴定。     

绵羊MHCⅡ类基因遗传多态性研究进展

主要组织相容性复合体(major histocompatibility complex,MHC)是广泛存在于脊椎动物体内的一类高度紧密连锁的基因群,绵羊MHC又称为绵羊淋巴细胞表面抗原(ovine lymphocyte antigen,OLA),位于绵羊20号染色体上,分为Ⅰ类、Ⅱ类和Ⅲ类区域,其中MHCⅡ类基因具有高度的基因多态性.文章综述了绵羊MHCⅡ类基因的分子结构及遗传多态性,重点总结了近十年来国内外不同绵羊品种MHCⅡ类基因遗传多态性的研究进展,并对绵羊MHCⅡ类基因未来的研究重点进行了展望.     

针叶树材管胞气体渗透流阻及其渗透系数

针对树材气体渗透性与气体在管胞中的流动特性和规律紧密相关，研究管胞的气体渗透流阻，可以获得关于针叶树材气体渗透性更深入的认识。本文从针叶树材管胞解剖结构出发，运用流体力学理论，导出了管胞3个纹理方向渗透气体流阻的数学表达式，并由此计算了针叶树材管胞的气体渗透系数。计算结果表明，管胞流阻可以描述气体渗透阻力的分布情况，反映气体渗透性在3个纹理方向的差异，在木材细胞层次揭示针叶树材气体渗透性的机制。     

Effects of soluble tea polysaccharides on hyperglycemia in alloxan-diabetic mice

The effects of tea water extracts (TWE), crude tea polysaccharides (CTP), and a tea polysaccharide fraction (TPF) were tested on hyperglycemic diabetic mice. Results indicated that TWE, CTP, and TPF could significantly decrease fasting blood glucose (FBG) and glucosylated serum protein (GSP) in alloxan-induced diabetic mice compared to the control group. In vitro antioxidant activities of TWE, CTP, and TPF for scavenging hydroxyl radicals and superoxide radicals decreased with the degree of purification and were lowest for TPF. High-performance gel permeation chromatography (HPGPC) and component analysis revealed the molecular mass distribution and constituents of TWE, CTP, and TPF, indicating that a 100-120 kDa fraction contained the hypoglycemic activity. This fraction was essentially composed of polysaccharides (approximately 90%) with substantial amounts of arabinogalactan proteins. The second-derivative IR spectra of TWE, CTP, and TPF with peak intensity around 1075 and 1045 cm(-1), which characterize galactopyranose in the backbone and arabinofuranose units in side branches, respectively, further substantiated the importance of the arabinogalactan proteins. Taken together, the results indicate that a soluble tea polysaccharide is the major hypoglycemic factor in tea and that this polysaccharide may be developed to a potential natural hypoglycemic functional ingredient.     

Lead optimization and insecticidal activity of analogues of daphneolone isolated from Stellera chamaejasme L

Starting from the chemical structure of the botanical aphicides 1,5-diphenyl-1-pentanone and 1,5-diphenyl-2-penten-1-one, extracted from Stellera chamaejasme L., the authors designed and synthesized a series of novel compounds following the concept of bioisosterism. Their structures were established on the basis of (1)H NMR and GC-MS spectra, and the insecticidal activities of the compounds were evaluated against Aphis gossypii Glover. The results demonstrated that the substitution of a heterocycle for the phenyl ring was favourable. Thus, further modification of compound 2n, containing a furan ring, which showed excellent activity (LC(50) = 0.85 g L(-1)), is of some promise.