酚醛树脂的改性   总被引：4，自引：0，他引：4  

艾军  翁向丽 《东北林业大学学报》1996,24(6):66-69

用ＤＳＣ分析技术研究了改性树脂的固化过程，确定了最佳固化温度。且发现随甲醛／苯酚的用量摩尔比增加。固化温度有下降的趋势；对改性树脂进行了力学性能测试，同时与普通酚醛树脂进行了比较。结果表明，实验合成的改性树脂的粘结性及柔性性较普通酚醛树脂有明显改善。  相似文献   

污泥电渗透脱水后热干燥过程中粘壁特性研究     

李国富  于晓艳  张书廷 《安徽农业科学》2013,(25):10467-10469

采用电渗透脱水技术作为污泥热干燥的前处理技术,考察了电渗透脱水后污泥含水率以及干燥方式对热干燥过程中污泥粘壁特性的影响.结果表明,电渗透脱水技术有效降低了污泥的粘壁强度.当采用间接干燥时,电渗透脱水后阴阳两极的污泥粘壁强度分别降低了64.5％和92.0％;而采用直接干燥时,电渗透脱水后阴阳两极的污泥粘壁强度则分别降低了69.2％和92.0％.电渗透脱水后,污泥含水率是影响污泥粘壁强度的重要因素之一.污泥电渗透脱水之后,阴极的污泥粘壁强度先随含水率的降低逐渐增大,当污泥含水率降至60％时,污泥的粘壁强度达到最大,之后反而开始减小;而阳极的污泥粘壁强度却接近0.相比间接干燥方式,电渗透脱水后直接干燥方式可降低污泥的粘壁强度.直接干燥方式下,阴极的污泥粘壁强度约为间接干燥下的0.87倍;而阳极的污泥粘壁强度接近0.  相似文献   

Coating performance on glutaraldehyde-modified wood     

Zefang Xiao  Haiou Chen  Carsten Mai  Holger Militz  Yanjun Xie 《林业研究》2019,(1):353-361

Scots pine(Pinus sylvestris L.) panels were modified with glutaraldehyde(GA) to various weight percent gains and subsequently coated with several commercial coatings. The drying rate and adhesion of the coatings on the modified wood were measured; the coated/modified woods were exposed outdoors to analyze how the wood modifications influence the coating deterioration. The results showed that GA modification caused an increase in the drying rate of the waterborne coatings, but had no influence on drying of tested solvent-borne coatings. GAmodification did not change the dry adhesion but reduced the wood strength in a pull-off test. Wet adhesion of waterborne coatings was improved, while that of the solvent-borne coatings tended to be somewhat reduced. During 22 months of outdoor weathering, the coated/modified samples exhibited lower moisture content than the coated/unmodified samples, but GA modification didn't contribute a substantially synergistic effect with surface coatings on resistance to weathering.  相似文献   

Molecular mechanisms of pathogenicity of Mycoplasma mycoides subsp. mycoides SC     

Pilo P  Frey J  Vilei EM 《Veterinary journal (London, England : 1997)》2007,174(3):513-521

Mycoplasma mycoides subsp. mycoides SC, the aetiological agent of contagious bovine pleuropneumonia (CBPP), is considered the most pathogenic of the Mycoplasma species. Its virulence is probably the result of a coordinated action of various components of an antigenically and functionally dynamic surface architecture. The different virulence attributes allow the pathogen to evade the host's immune defence, adhere tightly to the host cell surface, persist and disseminate in the host causing mycoplasmaemia, efficiently import energetically valuable nutrients present in the environment, and release and simultaneously translocate toxic metabolic pathway products to the host cell where they cause cytotoxic effects that are known to induce inflammatory processes and disease. This strategy enables the mycoplasma to exploit the minimal genetic information in its small genome, not only to fulfil the basic functions for its replication but also to damage host cells in intimate proximity thereby acquiring the necessary bio-molecules, such as amino acids and nucleic acid precursors, for its own biosynthesis and survival.  相似文献   

土壤-金属界面水膜粘附规律的试验研究   总被引：3，自引：0，他引：3  

卢韶芳  石要武  任露泉 《农业机械学报》1999,30(2):1-6

依据土壤粘附机理及界面水膜理论,利用由土壤粘附力测试仪,界面水膜测量仪等设备组成的多功能试验台采用化学的测试方法,对界面水膜的平均面积及厚度进行了定量测量,并对界面粘附规律进行了定量研究建立了界面水膜粘附规律的数学模型。  相似文献   

油菜联合收获机筛面粘附物摩擦特性   总被引：6，自引：0，他引：6  

李耀明  马征  徐立章 《农业机械学报》2010,41(12):54

The main ingredients and structure of rape adhesive materials on cleaning sieve were analyzed for sieve hole blocking and multiply increased cleaning loss caused by the adhesive materials. Size distribution of rape adhesive materials on cleaning sieve was obtained. 77% of the adhesive materials’ size were from 0.3mm to 2.5mm, and the main ingredients were distinctly different with different size range. Friction coefficient tests of rape nutshell, rape stalk & the adhesive materials were carried out. It was pointed out that their friction coefficients were commonly increased with the raise of their moisture, and the friction coefficients between the adhesive materials and metal reached to 0.71.  相似文献   

CD14沉默的猪小肠上皮细胞系的建立及其对大肠杆菌黏附能力的变化分析     

戴超辉  甘丽娜  钦伟云  孙寿永  朱国强  吴圣龙  包文斌 《农业生物技术学报》2016,(3):323-331

白细胞分化抗原14(cluster of differentiation antigen 14,CD14)在先天性免疫和适应性免疫反应中都发挥重要调控作用,本研究旨在构建猪(Sus scrofa)CD14基因的短发夹RNA (short hairpin RNA,shRNA)干扰载体,包装成慢病毒,转染猪小肠上皮细胞,在细胞水平上进行相关功能探讨.本研究参照CD14基因(GenBank登录号:EF626695.1)全长编码区序列,设计4个靶向猪CD14基因的shRNA干扰序列,将其克隆至慢病毒表达载体质粒中,分别命名为pGLV3-CD14-1、pGLV3-CD14-2、pGLV3-CD14-3和pGLV3-CD14-4,以及阴性对照pGLV3-CD14-NC.包装成功后转染猪小肠上皮细胞系IPEC-J2,利用qRT-PCR检测其干扰效率.选择干扰效率最高的慢病毒进行药筛,获得CD14基因稳定沉默的猪小肠上皮细胞系.大肠杆菌(Escherichia coli)黏附实验检测大肠杆菌F18ab和F18ac对CD14基因沉默小肠上皮细胞黏附能力的变化.结果表明,本研究成功构建4个shRNA表达载体,包装成的慢病毒均能降低猪CD14mRNA表达水平,其中pGLV3-CD14-3慢病毒的干扰效果最好,其干扰效率达到94.6％;CD14基因沉默后F18ab对小肠上皮细胞的黏附能力显著增强,而F18ac虽然也有上调,但并未产生显著性差异.研究结果表明,CD14基因沉默后的小肠上皮细胞对大肠杆菌F18ab的黏附能力显著增强,CD14基因可能在小肠上皮细胞抵御大肠杆菌F18ab感染过程中发挥了重要的调控作用.慢病毒介导的CD14沉默的猪小肠上皮细胞系的建立,不仅为在细胞水平研究CD14基因功能提供了有效模型,也为进一步探究其所在的Toll样受体/白介素-1受体(toll-like receptors/interleukin-1 receptor,TLRs/IL-1 R)信号通路在猪肠道病原微生物引起的免疫反应和抵御病原入侵的调控机制奠定了基础.  相似文献   

环境胁迫对双歧杆菌黏附能力和黏附相关蛋白的影响     

朱德全  栗金柳  王茗悦  孟祥晨  许龙  周清波  王长平  薛勇 《安徽农业科学》2016,44(21):131-133

双歧杆菌是天然存在于人和动物肠道的微生物,对宿主发挥生物屏障、调节肠道菌群、提高免疫、抗炎和抗肿瘤等有益作用,所以经常以益生菌的形式添加到乳制品和其他食品中。双歧杆菌的黏附定植是持续发挥益生作用的前提基础。然而,双歧杆菌在生产、包装、运输、储藏和消费过程中受到许多环境胁迫因素(如热、氧、酸、胆盐和渗透压等)的影响。这些环境因素会影响双歧杆菌黏附能力和黏附相关蛋白的表达。对环境胁迫对双歧杆菌存活的影响、双歧杆菌黏附能力的影响因素和环境胁迫对黏附相关蛋白的影响等方面的研究进展进行了综述。  相似文献   

莱芜黑猪a1岩藻糖转移酶基因(FUT I)不同基因型对大肠杆菌F18抵抗力研究   总被引：1，自引：0，他引：1  

王继英  郭建凤  孙守礼  郭立辉  蔺海潮  王诚  武英 《华北农学报》2009,24(5)

为了研究不同猪种(山东省地方猪种莱芜黑猪和引进猪种大约克)和FUT I不同基因型仔猪对肠毒性大肠杆菌F18(ETEC F18)的抵抗能力和肠黏膜上皮细胞对ETEC F18 黏附能力的差异,在采用PCR-RFLP技术对莱芜黑猪和大约克FUT I基因型检测的基础上,选取易感性和抗性断奶仔猪,利用野生型ETEC F18标准株进行试验猪口服细菌攻毒试验和肠黏膜黏附试验.由于多方面原因,接受ETEC F18细菌攻毒的试验猪均未发病,无法判断试验猪对ETEC F18的抵抗能力.ETEC F18标准菌株能与所有FUT I敏感基因型仔猪的小肠黏膜上皮细胞黏附,而不能与抗性基因型仔猪小肠上皮黏膜细胞黏附,莱芜黑猪与大约克的肠黏膜上皮细胞与E.coli F18的黏附特性并无品种差异.但是养猪生产实践中,莱芜黑猪极少发生断奶仔猪水肿和腹泻病.所以除FUT I基因外,也许本地猪种有其他导致遗传抗性的突变或抗性基因.  相似文献   

具有潜在抑制肠道致病菌能力的乳酸菌的筛选     

陈大卫  刘莎莎  黄玉军  郭蕾  张蓉 《安徽农业科学》2017,45(34):78-80,122

[目的]从实验室保藏的乳酸菌中筛选出耐酸耐胆盐能力较强的乳酸菌,并研究其对肠上皮细胞的黏附能力及对肠道病原菌的抑制能力。[方法]通过模拟人工胃肠液及体外与IEC-6细胞共培养来分别研究乳酸菌的耐酸耐胆盐能力及对细胞的黏附能力,并利用单层琼脂平板扩散法测定其抑菌效果。[结果]试验的27株乳酸菌中,10株乳酸菌在p H 3.0的人工模拟胃液中培养3 h的存活率均大于44.00%,在p H 8.0的人工模拟肠液中培养4 h的存活率均大于51.56%,在含0.30%胆盐的培养基中培养24 h的存活率均大20.00%;其中菌株C13、A03、A17及A90对IEC-6细胞的黏附个数均大于8个/cell;菌株C13、A03对艰难梭菌、沙门氏菌和大肠杆菌的抑制能力较强,抑菌圈直径均大于22 mm。经16S rRNA测序将C13和A03分别鉴定为鼠李糖乳杆菌(Lactobacillus rhamnosu)和植物乳杆菌(Lactobacillus plantarum)。[结论]L.rhamnosu C13、L.plantarum A03的耐酸耐胆盐能力及对上皮细胞的黏附能力较强,对肠道病原菌有较好的抑制作用,可作为良好的抑制肠道病原菌的候选益生菌株。  相似文献