Effect of sodium laurate on ruminal fermentation and utilization of ruminal ammonia nitrogen for milk protein synthesis in dairy cows

A crossover design trial with 4 ruminally and duodenally cannulated lactating dairy cows was conducted to study the effect of sodium laurate on ruminal fermentation, nutrient digestibility, and milk yield and composition. The daily dose of sodium laurate (0, control or 240 g/cow, LA) was divided in 2 equal portions and introduced directly into the rumen through the cannula before feedings. Ruminal samples (29 in 114 h) were analyzed for fermentation variables and protozoal counts. Sodium laurate had no effect on ruminal pH and total and individual volatile fatty acids concentrations. Ruminal ammonia concentration, ammonia N pool size, and the irreversible loss of ammonia N were unaffected by treatment. Compared to control, protozoal counts were reduced by 91% by LA. Carboxymethylcellulase and xylanase activities of ruminal fluid were decreased (by 40 and 36%, respectively), and amylase activity was not affected by LA compared with control. Flow of microbial N to the duodenum was reduced by LA. Dry matter intake and apparent total tract digestibility of dry matter, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber were not different between the 2 treatments. Milk yield, fat-corrected milk yield, milk fat and protein concentrations and yields, and milk urea N content were not affected by treatment. Sodium laurate did not affect transfer of ruminal ammonia-15N into bacterial or milk protein. In conclusion, LA at approximately 0.3% of the rumen weight reduced ruminal protozoal population and had a negative effect on fibrolytic activities of ruminal fluid and microbial protein flow to the intestine. Treatment had no other significant effects on ruminal fermentation, total tract digestibility, or transfer of ruminal ammonia-15N into milk protein.     

ZrOCl_2·8H_2O/USY催化月桂酸与月桂醇的酯化反应

采用浸渍法制备了负载型ZrOCl2.8H2O/USY催化剂,并用XRD、SEM等对其进行了表征。以ZrOCl2.8H2O/USY为催化剂,考察了其对月桂酸与月桂醇酯化反应的催化性能。以月桂酸的转化率为考察指标,讨论了催化剂活性以及各种因素如催化剂用量、反应溶剂、反应时间对该酯化反应月桂酸的转化率的影响。实验结果表明,n(月桂酸)∶n(月桂醇)=1∶1,30%(质量分数)ZrOCl2.8H2O/USY为催化剂,反应溶剂为氯代苯,当催化剂用量为反应物总质量的5.0%,溶剂回流条件下反应16 h,月桂酸的转化率达95.2%。     

ZrOCl2?8H2O/USY催化月桂酸与月桂醇的酯化反应研究

采用浸渍法制备了负载型ZrOCl2•8H2O/USY催化剂,并用XRD、SEM等对其进行表征。以ZrOCl2•8H2O/USY为催化剂考察了其催化月桂酸与月桂醇酯化反应的催化性能。以月桂酸的转化率为考察指标,讨论了催化剂活性以及各种因素如催化剂用量、反应溶剂、反应时间对该酯化反应酯化转化率的影响。实验结果表明,月桂酸与月桂醇的摩尔比为1:1,30 %（质量分数）ZrOCl2•8H2O/USY为催化剂,反应溶剂为氯代苯,当催化剂用量为反应物总质量的5.0 %,溶剂回流条件下反应时间为16 h,月桂酸的转化率达到95.2 %。     

月桂酸与二甲胺合成N,N-二甲基月桂酰胺的研究

以月桂酸和二甲胺为原料,在Cu基催化剂作用下,采用高压釜反应合成N,N-二甲基月桂酰胺。研究了温度、压力、原料配比、催化剂用量和时间等对月桂酸转化率和N,N-二甲基月桂酰胺选择性的影响,并考察了升温速率对产物色泽的影响。结果表明:在180℃,2.0 MPa,n(二甲胺)∶n(月桂酸)=1.4∶1,催化剂用量为月桂酸质量的3.0%,反应时间6 h,转速600 r/min,升温速率10℃/min的优化工艺条件下,月桂酸转化率达到95.8%,N,N-二甲基月桂酰胺选择性达到98.6%,且产物色泽较淡。     

2024铝合金超疏水表面的制备及其耐蚀性能

目的 在2024铝合金基体上制备超疏水表面,从而提高自清洁性能和耐腐蚀性能。方法 采用硫酸和草酸钛钾混合电解液阳极氧化,用月桂酸乙醇溶液修饰,在铝合金基体上制备超疏水表面,用扫描电子显微镜（SEM）、红外光谱和光学接触角测量仪观察、分析超疏水表面形貌、化学结构和润湿性,用电化学交流阻抗和极化曲线测试研究超疏水表面在3.5%氯化钠中的耐蚀性。结果 20 V恒电位阳极氧化时间小于90 min时,随着时间的增加,接触角增大。铝合金在0.5 mol/L硫酸和0.01 mol/L草酸钛钾混合电解液中阳极氧化90 min,并在5%（质量分数）的月桂酸乙醇溶液中修饰1.5 h,能制备出最优的超疏水表面,接触角为157.99°。在3.5%氯化钠中浸泡14天后,超疏水铝的交流阻抗值高于空白铝4个数量级,Tafel极化曲线解析表明,保护效率为99.92%。结论 在低浓度硫酸中对铝阳极氧化,并用月桂酸修饰能够成功制备出超疏水表面。所得表面展现出良好的耐腐蚀性,并且耐孔蚀性能得到改善。     

Highly enhanced bactericidal effects of medium chain fatty acids (caprylic,capric, and lauric acid) combined with edible plant essential oils (carvacrol,eugenol, β-resorcylic acid,trans-cinnamaldehyde,thymol, and vanillin) against Escherichia coli O157:H7

Medium chain fatty acids (MCFAs) and essential oils (EOs) are known to be natural antimicrobials, but their combined effects have not been fully investigated. The objective of the present study was to examine the bactericidal effects of various combined treatments of MCFAs [caprylic (CA), capric (CPA), and lauric acid (LRA)] and EOs [carvacrol (CAR), eugenol (EUG), β-resorcylic acid (RA), trans-cinnamaldehyde (TC), thymol (TM), and vanillin (VNL)]. Escherichia coli O157:H7, was treated with 1) control (2% ethanol), 2) MCFA alone, 3) EO alone, and 4) different combinations of MCFAs and EOs at 37 °C for 5 and 10 min. Synergistic bactericidal effects were observed with combined treatments; the log reduction in viable bacteria in response to the combined treatments was much greater than the sum of the effects of the two compounds applied individually. For example, individual treatment with 0.2 mM CPA (0.004%) and 0.4 mM RA (0.006%) for 5 min resulted in a negligible reduction in bacterial load (0.25 and 0.21 log reduction, respectively), whereas combined treatment at the same concentrations and for the same time reduced the bacterial population in the test sample to an undetectable level (initial population: 7.51 log CFU/ml; detection limit: 1 CFU/ml). The ranking of EOs showing the highest bacterial killing activities when combined with MCFAs was generally RA, CAR, TM > EUG > TC > VNL. All the antimicrobials used in this study are natural compounds that have been widely used in industry, so they are both consumer- and user-friendly. Combined treatment can overcome the disadvantages of MCFAs and EOs such as unpleasant odor and high cost because the required concentrations can be reduced. Our results indicate that the combined treatments used here could be successfully used to eliminate foodborne pathogens, significantly improving the microbiological safety of foods.     

树枝状聚(胺-酯)的自组装及其在染料分子相转移中的应用

通过静电力自组装制得了树枝状聚(胺-酯)-月桂酸(PAE(NH2)8-LA),并利用FTIR技术对PAE(NH2)8-LA进行了表征;考察了月桂酸含量、PAE(NH2)8浓度及水相pH对染料相转移率的影响。实验结果表明,染料的相转移率随月桂酸含量和水相pH的增大呈先增大后减小的趋势,随PAE(NH2)8浓度的增大而增大。在20 mL质量分数为9.09%的月桂酸甲苯溶液、10 mL浓度为4.2×10-4mol/L的PAE(NH2)8水溶液与10 mL浓度约为1.200×10-5mol/L的染料水溶液的混合液中,当水相pH分别为7.72,6.64,7.72时,染料达旦黄、甲基橙、二甲酚橙的相转移率分别达到最大值(49.60%,41.35%,35.58%)。     

月桂酸改性生物质材料处理乳化油的机理

油污染对环境、生物和经济产生了不利的影响。目前,诸多研究均希望得到一种有效、简单且价廉的除油方法。为了提高对含乳化油废水的处理效果,以玉米芯和花生壳为原料,采用月桂酸对其进行改性,并且利用扫描电镜、比表面积测试和红外光谱等测试手段研究生物质材料的改性和处理含乳化油废水的机理。研究发现,月桂酸改性是利用月桂酸上含有的羧基和生物质材料的纤维素、半纤维素和木质素上含有的羟基发生的酯化反应,形成的酯基链接月桂酸本身的烷基链,增强了亲油疏水性,同时也有造孔的作用即进一步增大微孔和提高孔隙率,由于改性材料是通过亲油性烷基链和微孔吸附油粒子,因此这两者的共同作用提高了材料的吸油能力。利用石油醚萃取水中油分,采用紫外分光光度法测定水中的油浓度。这种方法能够更加直接地看出含乳化油废水的处理程度,也更加贴近实际工程概况。研究表明,原始玉米芯和花生壳对含乳化油废水的油吸附容量分别是6.86 mg·g^-1和5.21 mg·g^-1,经月桂酸改性后,其吸附容量有了较大提高,分别达到了10.79 mg·g^-1和7.44 mg·g^-1。因此,当处理含乳化油废水时,利用月桂酸改性玉米芯和花生壳不仅能高效率除油,而且基于以废治废,是一项相当环保的措施     

月桂酸调控制备高光催化活性TiO2纳米晶

以钛酸丁酯为钛源、月桂酸为添加剂,采用简单溶剂热法合成了TiO₂纳米晶。结合XRD与TEM手段,以光催化降解亚甲基蓝染料为探针反应,考察了月桂酸与钛酸丁酯的摩尔比以及温度对所合成的TiO₂纳米晶的结构及其光催化性能的影响,并探讨了该体系下TiO₂纳米晶的生长机理。结果表明,月桂酸的存在有利于提高所合成TiO₂的结晶度,适当的月桂酸与钛酸丁酯的摩尔比是制备催化活性较高的TiO₂的必要条件;随着合成温度的升高,所得TiO₂的晶型由纯锐钛矿型向锐钛矿与金红石混合型转变,在200℃时所制备的TiO₂纳米晶的形貌规则、分散性高、光催化活性好。在月桂酸合成体系中,TiO₂晶粒生长符合定向吸附生长机制。     

低熔点高硬度特种蜡的研究与开发

采用聚乙烯蜡和月桂酸作为石蜡改性剂,考察了改性工艺条件和改性剂加入量对石蜡性能的影响。结果表明：最佳工艺条件为改性时间3 h、改性温度130 ℃、搅拌速率600 r/min,聚乙烯蜡添加量为5%,月桂酸的添加量为8%;通过对两种添加剂的调合,制备出滴熔点低和硬度适宜的改性石蜡产品;在此基础上,以聚乙烯蜡量为5%、月桂酸量为8%、硬脂酸为0~25%作为复合添加剂,可以得到滴熔点更低且硬度也有所提高的改性蜡;并采用SPSS软件进行线性回归,得出聚乙烯蜡、月桂酸和硬脂酸的添加量与石蜡滴熔点、针入度（25 ℃）的关系。