超重力旋转填料床中柠檬酸钠法脱除低浓度SO_2

在超重力旋转填料床中以柠檬酸-柠檬酸钠缓冲溶液为吸收液进行模拟烟气中SO2吸收的实验。考察了超重力因子(β)、液气比(L/m3)、入口烟气中SO2质量浓度、气体流量、吸收液中柠檬酸浓度、pH值等对SO2脱除率(η)和气相传质系数(KGa)的影响。实验结果表明,η和KGa随超重力因子、液气比(L/m3)、吸收液中柠檬酸浓度和pH的增加而增加,随入口烟气中SO2浓度的增加先增大后降低,随气体流量的增加而降低。采用超重力旋转填料床用柠檬酸-柠檬酸钠缓冲溶液吸收SO2的最佳工艺条件是:吸收液中柠檬酸浓度1.0mol/L,初始pH 4~5,液气比3L/m3~7L/m3,超重力因子54.53~90.14。在此条件下,出口气体中SO2质量浓度低于80mg/m3,η稳定在98%左右。     

碳酸二异十三酯润滑油基础油的合成

碳酸二异十三酯是一种性能优良的合成润滑油基础油。在甲醇钠的催化作用下,以异十三醇和碳酸二甲酯为原料合成了碳酸二异十三酯。研究了催化剂用量、原料配比、反应时间及温度等因素对酯交换反应的影响。结果表明,较佳合成工艺条件是:催化剂甲醇钠∶碳酸二甲酯=0.02∶1(物质的量比),异十三醇∶碳酸二甲酯=2.4∶1(物质的量比),反应时间2 h,反应温度160℃。实验室产品收率达80%以上,产品黏度指数介于80～90,产品倾点低于-40℃,100℃黏度大于4 mm2/s,适合于做合成润滑油基础油。碳酸二异十三酯合成油应用于SL 5W-30汽油机油中,在低温性能方面表现良好,能够达到低温指标要求。用红外光谱和质谱对反应产品进行了结构确定。     

Is rumen development in newborn calves affected by different liquid feeds and small intestine development?

The objective of the study was to determine the effect of different liquid feeds on calf small intestine and rumen development. Twenty-one bull calves (5 ± 1 d old) were randomly allocated to 3 groups and fed whole milk (WM), milk replacer (MR; 22% CP and 17.5% fat), or MR supplemented with sodium butyrate (MR+SB; 0.3% as fed). Liquid feed dry matter intake was equal between treatments and amounted to 1% of BW at the beginning of the trial. Starter diet was offered ad libitum. Animals were slaughtered at 26 (±1) d of age. Calves fed WM had higher average daily gain in the whole trial and higher starter diet dry matter intake between d 15 to 21 of the trial as compared with calves fed MR and MR+SB. Calves fed MR lost on average 1.4 kg of BW within first 14 d of the trial and their BW tended to be lower at d 7, 14, and 21 of the study as compared with calves fed MR+SB. The empty jejunum and ileum weight, crypt depth, mitotic index in the middle jejunum were higher, and apoptotic index tended to be lower in calves fed WM as compared with calves fed MR and MR+SB. Calves fed WM also had higher aminopeptidase N activity in the middle jejunum and tended to have higher maltase activity in the distal jejunum as compared with calves fed MR and MR+SB. The mitotic index was higher and apoptotic index was lower in the middle jejunum, and aminopeptidase A activity tended to be higher in the distal jejunum of calves fed MR+SB as compared with those fed MR. Calves fed WM had greater papillae length and width, and tended to have greater muscle layer thickness as compared with calves fed MR and MR+SB. Reticulorumen weight, reticulorumen weight expressed as percent of whole stomach weight, and papillae length and width were higher in calves fed MR+SB as compared with those fed MR. Additionally, calves fed WM had higher plasma glucose and urea in the whole trial period as compared with calves fed MR and MR+SB, and plasma glucose was higher in calves fed MR+SB as compared with those fed MR. Significant positive Pearson correlations were found between small intestine and reticulorumen weights as well as between activity of brush border lactase, maltase, aminopeptidase A, and aminopeptidase N and reticulorumen weight. Different liquid feeds affect small intestine development, animal growth, solid feed intake and metabolic status of calves and this effect can indirectly influence the development of forestomachs.     

Short communication: effects of supplementation with pomegranate seed pulp on concentrations of conjugated linoleic acid and punicic acid in goat milk

The effects of feeding pomegranate seed pulp (PSP) on milk yield, milk composition, fatty acid profiles of milk fat, and blood metabolites were examined in this study. During a pretrial period, 27 multiparous southern Khorasan (Iran) cross-bred goats were fed a similar diet and dry matter intake, milk yield, and milk composition were recorded. After adaptation and based on pretrial records, the goats were randomly assigned to 1 of 3 experimental diets and were housed in individual stalls. Experimental diets included 0, 6, or 12% of PSP (dry matter basis) and were fed as total mixed rations ad libitum for a 45-d period. Diets were formulated to be isonitrogenous and isocaloric. Supplementation of PSP did not affect dry matter intake or average daily gain of goats. Milk yield was not affected by inclusion of PSP in the diet. Milk fat concentration of goats fed diets with 6 and 12% PSP increased, but milk fat yield, milk protein concentration, and milk solids-not-fat concentration of goats were not affected by diets. Feeding PSP did not affect blood glucose, cholesterol, urea N, triglyceride, or lipoproteins. Feeding goats a diet containing 12% PSP modified the milk fatty acid profile, including conjugated linoleic, punicic, and vaccenic acids.     

Exclusion of dietary sodium bicarbonate from a wheat-based diet: effects on milk production and ruminal fermentation

Milk production, rumen fermentation, and whole-tract apparent nutrient digestibility in response to feeding 20% steam-rolled wheat with or without sodium bicarbonate were evaluated in 12 Holstein cows averaging 165 ± 16 DIM. Cows were fed 1 of 2 isoenergetic and isonitrogenous diets containing either 0 or 0.75% sodium bicarbonate on a DM basis for 21 d in a crossover design. Rumen fluid samples were obtained 18 times during the last 2 d of each period, and fecal samples were collected on 12 occasions from d 18 to 21 of each period. Removal of sodium bicarbonate from the diet did not affect DMI (21.0 kg/d), yields of milk (30.8 kg/d), or milk components (1.16, 1.01, and 1.40 kg/d for fat, protein, and lactose, respectively). Whole-tract apparent digestibility of DM, CP, ADF, and NDF did not differ between the 2 treatments (75.3, 76.6, 67.2, and 63.6%, respectively). The mean rumen pH was 6.24 and was not affected by excluding sodium bicarbonate from the diet. Rumen NH₃-N (12.31 mg/dL) and lactic acid (3.63 mM) concentrations were not different, whereas total volatile fatty acids concentration tended to increase when sodium bicarbonate was present in the diet (110 vs. 116 mM). However, average concentrations of the individual volatile fatty acids, as a proportion of total volatile fatty acids, were not affected by treatment. In conclusion, dairy cow diets can include up to 20% steam-rolled wheat without the need for added sodium bicarbonate as long as the diets are formulated to meet the fiber requirements of the cow.     

Effects of cloprostenol sodium at final prostaglandin F2α of Ovsynch on complete luteolysis and pregnancy per artificial insemination in lactating dairy cows

Luteolysis is a key event in Ovsynch programs of lactating dairy cows. Studies indicate that as many as 20% of cows treated with a Presynch/Ovsynch program have delayed or incomplete luteolysis using dinoprost tromethamine. Cows must have complete luteolysis to have a chance to become pregnant. Dinoprost tromethamine has a short half-life of approximately 7 to 8 min. Cloprostenol sodium is more resistant to endogenous metabolism and is maintained in circulation for a longer time (half-life = 3 h). The objective was to determine if cloprostenol sodium could increase the percentage of cows with complete luteolysis and subsequent pregnancy per artificial insemination (P/AI) in lactating dairy cows compared with dinoprost tromethamine when administered within a presynchronization plus Ovsynch program for first artificial insemination (n = 652) and an Ovsynch resynchronization program for second or later AI (second+; n = 394). Blood samples were collected daily for 5 d beginning at the PGF_2α of Ovsynch in a subset of cows (n = 680) for first and second+ AI to measure circulating concentrations of progesterone (P₄) and estradiol (E₂). Complete luteolysis was defined as cows with functional corpus luteum (CL) at time of treatment and serum concentrations of P₄ <0.5 ng/mL at 56, 72, and 96 h after treatment. Percentage of cows with functional CL that had complete luteolysis after treatment was not greater for cloprostenol sodium compared with dinoprost tromethamine in first (79 vs. 80%, respectively) or second+ AI (70 vs. 72%, respectively). In addition, mean serum concentrations of P₄ were not less for cows treated with cloprostenol sodium following treatment. Pregnancy per AI of cows treated with cloprostenol sodium tended to be greater than dinoprost tromethamine for first (40 vs. 35%; respectively) but not second+ AI (23 vs. 21%, respectively). Cows with greater serum P₄ concentrations at time of PGF_2α of Ovsynch had a greater probability of undergoing complete luteolysis after PGF_2α of Ovsynch and pregnancy at 39 d after timed AI (i.e., 50% pregnant at 8 vs. 28% pregnant at 4 ng/mL P₄). Serum concentrations of E₂ at 56 h after PGF_2α of Ovsynch were a positive predictor of pregnancy at 39 d after timed AI. In summary, cloprostenol sodium tended to improve P/AI. Cows with greater serum concentrations of P₄ at time of PGF_2α of Ovsynch had a greater chance of luteolysis and pregnancy.     

海藻酸钠-胰蛋白酶微球的制备及药物释放性能

通过离子凝胶法制备出球形完好的海藻酸钠-胰蛋白酶微球.红外分析表明,微球中凝胶基质通过海藻酸钠的-COO-与Ca2+发生静电作用交联形成.SEM观察显示微球中存在蛋格结构及孔洞.考察了不同因素对微球载药率、包封率和体外释药率的影响.结果表明,海藻酸钠水溶液浓度越高释药率越低,当海藻酸钠与胰蛋白酶质量比为4,海藻酸钠水溶...     

硅酸钠对TC4钛合金微弧氧化电极参数及陶瓷膜的影响

硅酸钠是影响微弧氧化过程和微弧氧化膜结构的重要因素之一.采用恒压模式,以Na2SiO3,CH3COONa,EDTA·2Na为溶液,在TC4钛合金表面微弧氧化制备了陶瓷涂层,研究了Na2SiO3浓度对起弧电压,电极电流,陶瓷膜厚度、表面形貌、粗糙度以及陶瓷膜相组成的影响.结果表明:Na2SiO3有降低起弧电压和电极电流的...     

冷却水中杀菌剂次氯酸钠、异噻唑啉酮对不锈钢的侵蚀性比较

冷却水对不锈钢有腐蚀作用,在冷却水中分别添加杀菌剂次氯酸钠和异噻唑啉酮,采用极化曲线研究了次氯酸钠和异噻唑啉酮对TP304L不锈钢电极耐蚀性能的影响.结果表明:冷却水中次氯酸钠可以促进不锈钢的点蚀,随放置时间的延长冷却水对不锈钢的侵蚀性增加;冷却水中加入异噻唑啉酮对不锈钢的极化曲线不产生影响,在放置过程中冷却水对不锈钢...     

乙酸钠浓度对AZ91D镁合金锡酸盐转化膜的影响

镁合金的无铬化学转化处理已成为其防护技术研究的一个重要方向,为此,开发了一种以乙酸钠为主要成分的镁合金锡酸盐转化工艺,采用全浸腐蚀试验、扫描电镜(SEM)、X射线衍射(XRD)等方法研究了AZ91D镁合金在含不同乙酸钠浓度成膜液中所形成膜层的结构,并比较了膜层的耐腐蚀性能.结果表明:成膜过程中,随着成膜液中乙酸钠浓度的...