浅谈木质家具用胶黏剂的发展趋势

介绍了木质家具用胶黏剂的变化和发展趋势,重点综述了改性三醛胶(脲醛树脂胶黏剂、酚醛树脂胶黏剂和三聚氰胺-甲醛树脂胶黏剂)、高性能水性聚氨酯胶黏剂、再生资源类胶黏剂、热熔树脂胶黏剂的研究进展和发展趋势。     

3种植物胶物化性能的对比研究

利用天然植物资源通过纯化分离得到了亚麻胶和沙枣胶。对3种植物胶阿拉伯胶、沙枣胶和亚麻胶的理化指标、增稠性、协同增稠性、乳化和泡沫性能进行了对比研究,结果表明,沙枣胶和亚麻胶可以取代商品阿拉伯胶。     

PASSIM接装纸胶池式供胶系统的设计应用

PASSIM卷接机组接装纸供胶系统采用一级连续不间断供胶方式,在回流过程中胶水水分散失,尘埃增多,而且存在着供胶间歇断流现象,从而易产生漏气和掉嘴烟支。为此,结合PASSIM与PROTOS供胶系统的优点,设计了新型胶池式供胶系统,通过增设胶池、改进上胶器、增设三级刮胶装置和胶位检测器等,实现了连续、稳定和清洁供胶,杜绝了漏气和掉嘴烟支产生,保证了产品质量。     

CT条盒包装机胶缸系统的改进

针对CT包装机条盒胶缸系统存在的胶缸滚轮不统一、上胶量不易调整、胶缸液面容易结皮和浪费乳胶等现象进行分析。通过统一胶缸滚轮、装分体控制刮胶片和加装一片隔板以缩小胶缸容量等措施,达到了胶缸胶滚备件统一、各胶滚的上胶量自如调节、减少乳胶结皮和乳胶浪费的目的,既解决了操作和调整难的问题,又节约了卷烟的制造成本。     

国内外生物质胶黏剂的研究与应用

具体介绍了生物质胶黏剂中的几大胶种,主要包括蛋白质胶黏剂、淀粉胶黏剂、木质素胶黏剂和热解生物油胶黏剂,并详述了各类胶黏剂的优缺点与国内外近几年来关于它们的改性研究。     

黄原胶和魔芋胶抑制碱诱导鸭蛋清凝胶的高温液化

本研究分别将黄原胶和魔芋胶添加至鸭蛋清中制备碱诱导凝胶,以探究亲水胶体对凝胶高温液化的抑制作用,结果表明:与对照组相比,添加亲水胶后的蛋清凝胶黏度、储能模量和损耗模量增大明显(p<0.05),褐变强度增加了7.99%和33.21%;当黄原胶和魔芋胶的浓度由0.50%增加至1.50%,凝胶硬度值提高49.60%和119.56%,穿刺强度提高20.59%和78.42%,持水性提高1.02%和9.47%,且添加黄原胶的蛋清凝胶硬度、穿刺强度和持水性均显著大于魔芋胶(p<0.05)。两种胶的浓度均为1.00%时,蛋清凝胶的感官评分最高。两种亲水胶的加入会改变蛋白质的二级结构及凝胶内部的分子间作用力:黄原胶量的增加显著降低了离子相互作用(p<0.05),无规则卷曲减少了41.23%,α-螺旋增加了81.29%;魔芋胶量的增加显著降低了疏水相互作用(p<0.05),β-折叠减少了34.97%,无规则卷曲和α-螺旋分别增加了68.97%和70.37%;氢键和二硫键均随两种胶浓度的增加而增强。综上所述,添加黄原胶和魔芋胶均能抑制碱诱导蛋清凝胶在高温处理过程中的液化现象,且加入黄原胶所形成的凝胶质构特性和持水性优于魔芋胶,而魔芋胶对于凝胶褐变强度的影响大于黄原胶。     

瓜尔胶在薄页纸上的应用

介绍了瓜尔胶、阳离子淀粉(CS)和羧甲基纤维素(CMC)的特性,比较了非离子瓜尔胶、阳离子瓜尔胶、阴离子瓜尔胶的性能,实验了浆内添加瓜尔胶、采用CS和CMC部分替代非离子瓜尔胶对纸张强度和填料留着率的影响.结果表明,在薄页纸浆内添加非离子瓜尔胶具有增强和助留效果,采用CS和CMC部分替代非离子瓜尔胶,也能提高纸张的强度性能和填料留着率.     

沙蒿胶冷水溶部分和热水溶部分流变性研究

研究了沙蒿胶冷水溶和热水溶部分的流变性,沙蒿胶溶于冷水和热水中,其流变性有所不同.考察了浓度、温度、剪切力、pH、冻融等参数对沙蒿胶粘度的影响.沙蒿胶与瓜尔豆胶、黄原胶、海藻酸钠具有明显的协效性,与卡拉胶、壳聚糖、决明子胶、魔芋粉无协效性.     

GDX1包装机组条盒上胶装置的改进

GDX1包装机组原条盒上胶装置对上胶量缺乏有效控制,造成7个上胶点上胶不均匀,且零件受乳胶腐蚀需经常清洗、更换等,为此对该上胶装置进行了改进。设计了密闭式上胶装置,将原上胶器改为上胶嘴,上胶全过程采用PLC程序控制,保证了7个上胶点稳定均匀地上胶;乳胶在该装置中处于密闭状态,除喷胶嘴外,其他零件均不与胶液接触,从而减少了乳胶损耗,降低了工人劳动强度、配件损耗和设备故障率。     

植物胶的特性及在食品工业中的应用

简要介绍了阿拉伯胶、魔芋胶、黄蓍胶、刺梧酮胶、罗望子胶、卡拉胶、瓜尔豆胶、刺槐豆胶和亚麻籽胶的特性及在食品工业中的应用,并指出亲水植物胶体作为优良的功能性配料和可溶性膳食纤维的良好来源,对其进行研究和应用开发,具有重要的实用价值。     

环斑猛猎蝽对斜纹夜蛾低龄幼虫的捕食功能反应

为挖掘环斑猛猎蝽(Sphedanolestes impressicollis)对斜纹夜蛾(Spodoptera litura)的捕食潜力，在室内条件下研究了环斑猛猎蝽4龄若虫对斜纹夜蛾1龄、2龄和3龄幼虫的捕食功能、寻找效应、环斑猛猎蝽不同密度对捕食斜纹夜蛾的干扰效应以及捕食空间大小对环斑猛猎蝽捕食功能的影响。结果显示，4龄环斑猛猎蝽若虫对低龄斜纹夜蛾幼虫的捕食功能反应与Holling II模型相符，对1~3龄斜纹夜蛾幼虫的瞬时攻击率分别为0.979、0.999和0.164，处理时间分别为0.013、0.020和0.018 d，最大日捕食量分别为74.5、51.2和6.1头。4龄环斑猛猎蝽若虫的寻找效应与斜纹夜蛾低龄幼虫密度呈负相关，对斜纹夜蛾低龄幼虫的捕食作用率随自身密度的增加而下降。在捕食1龄斜纹夜蛾幼虫时，环斑猛猎蝽4龄若虫自身密度对其捕食能力干扰最大。因此4龄环斑猛猎蝽若虫对低龄斜纹夜蛾幼虫具有一定的捕食能力，可用于烟田斜纹夜蛾幼虫的绿色防控。      

分割辊结构对缆型纺纱质量的影响

针对传统环锭纺纱机存在纺纱加捻三角区导致纱线毛羽较多的现状,介绍了缆型纺纱的原理,分析了缆型纺纱中分割辊直径、分割槽宽度对66支澳毛和70支澳毛成纱毛羽和纱线耐磨性的影响规律.得出在沟槽宽度相同的情况下,分割辊直径越大,纱线毛羽越多;在分割辊直径相同时,随着沟槽宽度的增加,纱线毛羽数量增多.分割槽宽相同时,分割辊直径越小,纱线的耐磨性能越好.     

通过敲除聚谷氨酸合成基因提高纳豆杆菌纳豆激酶的生产效率

纳豆激酶是纳豆杆菌(Bacillus natto)产生的具有溶栓作用的酶,纳豆杆菌液体发酵时产生的聚谷氨酸(polygutamic acid,γ-PGA)使发酵液黏度升高,导致纳豆激酶分离纯化困难,成本较高,限制了其规模化生产。该研究采用同源重组双交换技术,敲除纳豆杆菌中合成γ-PGA的关键基因pgsB,降低发酵液中γ-PGA的含量和发酵液黏度,提高后续纳豆激酶的分离纯化效率。结果表明pgsB基因缺失株与野生型菌株相比,发酵液中γ-PGA产量显著下降,在发酵24 h时γ-PGA含量下降了57.9%。此外两者的细胞密度无明显差异,说明pgsB基因的缺失可显著降低发酵液黏度且对菌体的生长没有影响。使用超滤法纯化纳豆激酶的过程中,基因缺失株的纳豆激酶回收率比野生型提高了19.2%。因此,敲除pgsB基因后,纳豆激酶分离纯化的效率得到了提高,为纳豆激酶的工业化生产提供了新方法。     

影响鲜莲子机械去心定位精度的几何参数测量

基于最小二乘法建立了鲜莲子截面圆的圆心坐标、直径、圆度误差以及鲜莲子几何轴线与莲心轴线的同轴度误差的测量模型,借助三坐标测量机测量了鲜莲子沿莲心轴线方向各截面的轮廓参数,将测量数据代入测量模型计算得到鲜莲子各参数的结果。结果表明,鲜莲子圆度误差沿莲心轴线方向呈近似抛物线规律变化,越靠近最大截面位置其圆度误差越小,反之越大,最大截面处的圆度误差最小,其平均值为0.347 3mm;在以莲心轴线为基准时,鲜莲子几何轴线和莲心轴线的平均同轴度误差为0.914 0mm;基于该同轴度误差测量结果,鲜莲子机械去心时,其冲头直径比莲心直径至少要大0.914 0mm。     

Effects of DDT and lindane on thyroid function in the rat]

Using the previously described test method, the authors studied with the aid of iodine-131 labelled NaI the effects of daily doses of 30 and 75 mg DDT/kg of body weight, and of 12 and 36 mg of lindane/kg of body weight on the iodine and hormone metabolism in the rat. With DDT, the authors observed a marked increase of the thyroid mass and of the thyroid tri-iodothyronine and thyroxin levels and a simultaneous decrease of the thyroid iodine level. The values for serum iodine and protein-bound iodine were reduced. Serum thyroxin was slightly increased. Serum tri-iodothyronine was markedly increased, which was also true of the iodine fractions in the liver. Lindane was considerably less effective. Only the decrease of thyroid tri-iodothyronine and the simultaneous increase of thyroid thyroxin were striking. In the serum, both hormones remained unchanged. The values for the urine fractions of both the active principles were indicative of a hypofunction. The causes of the changes observed were discussed with regard to the findings of other authors. The present results permit the conclusion that the effects of the pesticides tested are obviously complex by nature.     

Effect of the alimentary factor on the immunobiologic reactivity of children's bodies]

Observations covered 66 healthy six-year old children of a childrens' home. The actual alimentation of the children was studied according to tabulated values for one year and 112 apportionoments. In the rations of actual nutrition a disturbed correlation of proteins, fats and carbohydrates was noted. Seasonal variations of the salival lysozyme activity were revealed against the background of the actual alimentation. The lowest antimicrobial activity of the lysozyme was recorded in the winter and spring seasons of the year. The low lysozyme activity of the saliva in spring may be explained by deficiency of the animal protein in the ration. In winter time added to the insufficient content of the animal protein were features specific for the day's routine, typical of this season. An addition of the animal protein to the actual nutritional rations of the children, in the form of eggs and nonfat dry milk and a correction of the proteins, fats and carbohydrates proportions in the rations led to a statistically significant rise in the lysozyme activity in the saliva of children during all the months of observation.     

The influence of the specific cutting force and cross-sectional geometry of a chip on the cutting force in the process of circular rip-sawing

in the process of circular rip-sawing of wood tissue. The specific cutting force represents a complex interaction between the geometry of the blade, the physical and mechanical properties of the tissue and the direction of cutting, i.e. the rotating angle of the tool. The analyses carried out confirm the appropriateness of the definition of the specific cutting force as the parameter independent of the cross-sectional geometry of the chip, i.e. independent of the technological parameters. The results of the analysis of the relation between the tangential component of the cutting force and the feed velocity, which at invariable values of the entrance and exit rotating angle of the tool directly determines the mean thickness of the chip, confirm the hypothesis on an exponential relation between the said variables. In the case of invariable geometric parameters of the tool, the specific cutting force is constant, while the relation between the cutting force and the technological parameters is merely a consequence of the influence of the parameter of cross-sectional area of the chip f _hm . For this research wood of two tree species was used, namely celtis wood (Celtis zenkeri Engel.) and manilkara wood (Manilkara fouilloyana Aubrev et Pellegr.).     

多圆孔辅助喷嘴喷孔结构参数灵敏度分析北大核心CSCD

为探究多圆孔型结构喷孔对喷气织机辅助喷嘴喷射性能的影响规律,获得更好的喷嘴结构和引纬质量,文章以多圆孔辅助喷嘴为研究对象,进行多圆孔辅助喷嘴结构参数灵敏度分析。首先,采用拉丁超立方采样(LHS)抽取所需实验样本并建立各样本的流场模型,获得最大出口速度作为性能评定指标。其次,基于支持向量回归机(SVR)建立辅助喷嘴结构参数与最大出口速度间的数学代理模型。最后,采用Sobol全局灵敏度分析法求解结构参数的灵敏度,得到结构参数对其最大出口速度的一阶灵敏度系数和全局灵敏度系数。结果表明:喷孔直径和孔心距对最大出口速度的影响较大,喷孔位置和喷孔锥度的影响较小。     

Ecological relationships between the prevalence of cattle shedding Escherichia coli O157:H7 and characteristics of the cattle or conditions of the feedlot pen.

This study was designed to describe the percentage of cattle shedding Escherichia coli O157:H7 in Midwestern U.S. feedlots and to discover relationships between the point prevalence of cattle shedding the organism and the characteristics of those cattle or the conditions of their pens. Cattle from 29 pens of five Midwestern feedlots were each sampled once between June and September 1999. Feces were collected from the rectum of each animal in each pen. Concurrently, samples of water were collected from the water tank, and partially consumed feed was collected from the feedbunk of each pen. Characteristics of the cattle and conditions of each pen that might have affected the prevalence of cattle shedding E. coli O157:H7 were recorded. These factors included the number of cattle; the number of days on feed; and the average body weight, class, and sex of the cattle. In addition, the temperature and pH of the tank water were determined, and the cleanliness of the tank water and the condition of the pen floor were subjectively assessed. The samples of feces, feed, and water were tested for the presence of E. coli O157:H7. E. coli O157:H7 was isolated from the feces of 719 of 3,162 cattle tested (23%), including at least one animal from each of the 29 pens. The percentage of cattle in a pen shedding E. coli O157:H7 did not differ between feedyards, but it did vary widely within feedyards. A higher prevalence of cattle shed E. coli O157:H7 from muddy pen conditions than cattle from pens in normal condition. The results of this study suggest that E. coli O157:H7 should be considered common to groups of feedlot cattle housed together in pens and that the condition of the pen floor may influence the prevalence of cattle shedding the organism.     

Sensory evaluation of the touch of a great number of fabrics

Evaluating fabric touch can be a great interest for the industry in order to match the quality needs of the consumer and the parameters of the manufacturing process. The present paper reports the approach of a panel used to categorize the touch of 43 different fabrics obtained through a change of five parameters of fabrication. Incomplete block design was chosen by the panelists for the evaluation of the samples. Analyses of the differences among samples were carried out with ANOVA. The Newman–Keuls test was used to evaluate the influence of the process parameters on the values of four sensorial attributes. The average rating of the attributes evaluated by the panel varied significantly with modification of the yarn count, the yarn torsion or the fabric tightness. This variation follows the textile know how.