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     

Preparation of novel reagents 4-alkoxytrityl chlorides and their reaction with methyl Α-d-glucoside

A series of novel 4-O-alkoxytrityl chlorides (1) with different chain lengths was synthesized as a novel reagent for obtaining 6-O-alkylated cellulose with high regioselectivity via trityl groups in one reaction step without the use of any protective groups. These chlorides were reacted with methyl -d-glucoside, which was used as a model compound, to examine the reactivities toward the primary hydroxyl groups of cellulose to afford a series of 6-O-alkylated methyl -d-glucosides in high yields. The product compounds were found to have interesting solubilities and thermal properties. Thus, newly prepared trityl chloride derivatives were found to be useful regioselective derivatization reagents on the primary hydroxyl group in carbohydrates, especially in cellulose.     

二次纤维酶水解生成葡萄糖的研究

将回收的废纸脱墨、洗净即为二次纤维。脱去其中的木质素和半纤维素，得纤维素，用纤维素酶水解生成葡萄糖。对温度、pH值、酶用量、时间分别进行单因素试验，通过测定水解液葡萄糖含量，找出水解的适宜条件：温度45℃，pH值4．8，酶用量8IU／g(对绝干原料)，产率可达60％以上。     

疏水改性羧甲基纤维素及其在废纸脱墨中的应用

以DMAc为溶剂,三乙胺为缚酸剂,十二酰氯为反应试剂,对羧甲基纤维素进行疏水改性,制备表面活性剂十二烷基酯化的羧甲基纤维素(CMC-R)。羧甲基纤维素与十二酰氯的质量比为1∶0.4,反应最佳温度为60℃,时间5 h。将合成的纤维素基表面活性剂CMC-R应用于旧新闻纸(ONP)脱墨,结果表明,单独使用CMC-R能提高废纸浆白度2.2%(ISO),纸浆的残余油墨量减少457.66 mm2/m2,减少了29.4%。而CMC-R与非离子表面活性剂脂肪醇聚氧乙烯醚(JFC)复配后,白度较CMC-R单独使用提高2.13%(ISO),残余油墨量减少3.18%。     

纤维素替代淀粉对肌原纤维蛋白凝胶特性的影响

【目的】 探究纤维素替代淀粉对肌原纤维蛋白凝胶特性的影响,为纤维素替代淀粉在香肠中的运用提供一定的理论依据。【方法】 以添加不同比例的淀粉/纤维素-肌原纤维蛋白为模拟体系,研究复合凝胶的持水性、色差、质构特性以及断裂形变时的应力应变,分析动态升温流变特性、蠕变回复特性,观察淀粉/纤维素-肌原纤维蛋白的空间分布和三维网络结构。【结果】 增加淀粉和纤维素的添加比例,可以改善复合凝胶的持水性和储能模量。淀粉和纤维素添加比例分别从0增加到2.0%时,硬度、咀嚼度逐渐增加到最大值,与对照组相比,硬度分别提高29.47%和43.69%,咀嚼度分别提高34.82%和41.58%,L*、白度有减小的趋势。复合凝胶断裂形变时应力应变结果表明,添加2.0%纤维素时的应力（9 681.86 Pa）为最大值,应变（1.14）为最小值。复合凝胶的蠕变模量值随着淀粉和纤维素添加比例增加而逐步减小,相同添加比例条件下纤维素组复合凝胶的蠕变模量值减小更明显。石蜡切片显示,淀粉和纤维素只是简单地镶嵌在凝胶网络结构中,并没有与蛋白发生交联,其中纤维素在肌原纤维蛋白凝胶体系中形成的不规则区域更大。微观结构显示,对照组表面粗糙,空洞较多;添加淀粉和纤维素后,复合凝胶变得均匀致密,空洞减少;相同添加比例条件下,纤维素组的蛋白网络结构具有更好的均匀性和致密性。【结论】 淀粉和纤维素添加到肌原纤维蛋白中,两者都可以改善复合凝胶的持水性、色差、质构特性、断裂形变时应力应变、流变特性以及微观结构,但是纤维素对复合凝胶的改善效果更显著。因此,纤维素作为淀粉替代物在凝胶类香肠中的应用具有可行性。     

Transgenic woody plants for biofuel

Transgenic trees as a new source for biofuel have brought a great interest in tree biotechnology. Genetically modifying forest trees for ethanol production have advantages in technical challenges, costs, environmental concerns, and financial problems over some of crops. Genetic engineering of forest trees can be used to reduce the level of lignin, to produce the fast-growing trees, to develop trees with higher cellulose, and to allow the trees to be grown more widely. Trees can establish themselves in the field with less care of farmers, compared to most of crops. Transgenic crops as a new source for biofuel have been recently reviewed in several reviews. Here, we overview transgenic woody plants as a new source for biofuel including genetically modified woody plants and environment; main focus of woody plants genetic modifications; solar to chemical energy transfer; cellulose biosynthesis; lignin biosynthesis; and cellulosic ethanol as biofuel.     

黄秋葵MYB转录因子的鉴定及与果实老化关系分析

黄秋葵(Hibiscus esculentus L.)纤维素和木质素的大量积累极易引起果实老化,而植物MYB转录因子参与纤维素和木质素等生物合成与沉积,在次生细胞壁形成中起着重要的调控作用。为研究MYB转录因子在黄秋葵老化中的作用,从黄秋葵果实转录组测序数据库中筛选得到10条功能注释为MYB基因的片段序列,克隆获得了HeMYB4、HeMYB6、HeMYB26、HeMYB28、HeMYB44、HeMYB46、HeMYB59、HeMYB86、HeMY108和HeMYB113的基因全长,分析其核苷酸及编码氨基酸序列特征,同时进行了亚细胞定位、磷酸化位点、功能域、进化等生物信息学分析。结果显示,10个MYB基因均定位于细胞质膜上,具有丰富的磷酸化位点和功能域,与拟南芥等物种中参与纤维素和木质素合成的MYB蛋白亲缘关系较近。通过实时荧光定量PCR分析黄秋葵MYB基因家族的10个基因在果实发育过程、采后常温贮藏期间的表达,结果发现,HeMYB46、HeMYB86、HeMY108的表达量与纤维素含量呈极显著正相关,推测上述基因在黄秋葵果实衰老过程纤维素合成中起重要作用;HeMYB46、HeMYB59的表达量与木质素含量呈极显著正相关,推测其在木质素合成中起到重要调控作用。本研究结果初步明确了黄秋葵MYB转录因子在黄秋葵老化过程中的作用, 为黄秋葵的生产、分子育种等提供了理论基础。     

乐业豆豉主要发酵微生物的筛选 鉴定及发酵性能研究

通过涂布分离和感官评定从广西乐业传统细菌型豆豉中分离和筛选出豆豉的主要发酵微生物DC8,经 形态特征、16S rDNA 序列比对及系统发育分析鉴定,菌株DC8 为枯草芽胞杆菌枯草亚种（Bacillus subtilis subsp. subtilis)。菌株DC8 的发酵性能较好,发酵制备的豆豉风味好,纤溶酶活性、DPPH 自由基清除活性、游离氨基酸含量 和酸可溶性多肽含量高,分别达到59.49(依2.37) IU/g、0.87(依0.07) mg Trolox/g、21.77(依1.31) mg/g 和46.14(依2.58) mg/g。结果 表明,菌株DC8 是制备细菌型豆豉的良好菌种。     

Cellulose acetate electrophoresis of canine plasma after fibrinogen precipitation by ethanol

Background: In routine canine medicine, anticoagulated blood is often the only sample sent to laboratories for diagnostic purposes. This hampers the interpretation of protein electrophoretic tracings because plasma contains fibrinogen, which migrates in the β–γ region. In human medicine, fibrinogen can be precipitated from plasma using ethanol. Objectives: The purpose of this study was to assess ethanol precipitation as a method for removing fibrinogen from canine plasma so as to facilitate the interpretation of electorphoresis results. Methods: Blood samples collected from 40 dogs were divided into plain tubes and tubes containing EDTA (n=20) or lithium–heparin (n=20). An aliquot of plasma from each sample was incubated with ethanol at a final concentration of 100 mL/L. Cellulose acetate electrophoresis was then performed on serum, plasma, and plasma treated with ethanol. To verify the efficiency of ethanol treatment, fibrinogen was added to 5 canine serum samples at final concentrations of 2.5, 5.0, and 10.0 g/L, and electrophoresis was performed before and after ethanol treatment. Results: Visual analysis of electrophoretograms from ethanol‐treated samples confirmed the disappearance of the fibrinogen peak from the β₂‐globulin region. Treatment with ethanol caused a significant decrease in the percentage of β₂‐globulins and a significant increase in the percentage of α₂‐globulins. Absolute values of most electrophoretic fractions were significantly decreased in ethanol‐treated plasma compared with serum. Conclusions: Ethanol treatment successfully removed fibrinogen from canine plasma and normalized electrophoretic profiles, but probably also precipitated proteins other than fibrinogen. Ethanol treatment is recommended to facilitate visual identification of abnormal monoclonal peaks, but not for determining absolute protein concentrations in electrophoretic fractions.     

不同浓度纤维素酶在双红葡萄酿酒中对颜色的影响

以‘双红’山葡萄为试材,通过用纤维素酶处理,对葡萄进行色素提取。结果表明:红色素最大吸收波长为530 nm。得出0.03 mol/L浓度的纤维素酶水溶液的色素提取效果最好,在料液比为1∶10,浸提温度40℃条件色素浸出率较高。颜色指标稳定后,0.03 mg/L的纤维素酶处理组L*值为26.9,透明度最低;a*值为18.6,红色色调最大;c*值为29.1,颜色最深;H*值为-53.6,红色色调最重。酿酒过程中以0.03 mg/L的纤维素酶处理组的全过程曲线波动最小,颜色最稳定。