In vivo electrochemical studies of dopamine clearance in subregions of rat nucleus accumbens: differential properties of the core and shell

The effects of the rodent hepatocarcinogens clofibric acid and diprofibrate on the activity of the peroxisomal fatty acyl-CoA oxidase, DNA synthesis, and apoptosis were compared in cultured rat and human hepatocytes. Rat hepatocytes expressed a 10-fold greater level of the peroxisomal fatty acyl-CoA oxidase compared to human hepatocytes. At the highest concentration (1.0 mM), both drugs induced a two- to threefold increase in this enzyme activity in both rat and human hepatocytes. Ciprofibrate (0.1 and 0.2 mM) caused a twofold increase in DNA synthesis in rat hepatocytes, whereas clofibric acid had no effect on DNA synthesis in these cells. In contrast, increasing concentrations of both clofibric acid and ciprofibrate produced inhibition of DNA synthesis in human hepatocytes. By using the terminal transferase dUTP-biotin nick end labeling technique, it was observed that 0.1 and 0.2 mM clofibric acid and ciprofibrate suppressed transforming growth factor-beta (TGF beta)-induced apoptosis by 50% in rat hepatocytes, but they had no effect on TGF beta-induced apoptosis in human hepatocytes. Although clofibric acid and ciprofibrate diminished TGF beta-induced apoptosis, they had no effect on the basal apoptotic levels in the rat hepatocyte cultures. However, both drugs significantly increased the percent of apoptotic cells in the human hepatocyte cultures. It is concluded that primary rat and human hepatocyte cultures respond differently to peroxisome proliferators. The differences in effects on DNA synthesis and apoptosis support the hypothesis that human liver cells are refractory to peroxisome proliferator-induced hepatocarcinogenesis.     

Protein density and its influence on metabolite concentration and nitrogen retention by Holstein cows in late gestation

Multiparous Holstein cows in late gestation were used in a completely randomized design to test the effects of prepartum protein supply on prepartum N balance, blood metabolite and hormone concentrations, and postpartum intake and milk production. Cows were assigned to one of three isocaloric diets that differed in amount of total dietary crude protein (CP) (10.6, 12.7, or 14.5% of dry matter) but not in CP degradability or solubility. All diets contained the following ingredients: corn silage, chopped grass hay, ground corn, soybean meal, expeller soybean meal, minerals, and vitamins. Following parturition, all cows were offered a similar diet. Nitrogen balance was measured on d 12 to 7 prior to the expected calving date. Cows were bled on d 5 prior to the expected calving date from just prior to feeding to 8 h postfeeding. As dietary CP increased, plasma glucose concentrations increased linearly, but no change was detected in plasma nonesterified fatty acids or serum insulin concentrations. Nitrogen intake, apparent and true digestibilities, fecal and urinary concentration of and N balance increased as the concentration of dietary protein increased. The efficiency of absorbed protein utilization decreased as protein intake increased. No change in postpartum intake or milk production was observed. An increase in N retention in late gestation cows that were in positive N balance did not increase postpartum milk production.     

微生物附着力测试装置的研究进展

新型防污涂料发展迅速,因此需要更好的测试方法对其进行性能评价。生物在材料表面的附着力大小是影响其是否在材料表面形成永久污损的关键参数,因此建立对材料表面生物附着力的测试和评价方法对评价材料的防污能力具有重要意义。目前有几种附着力测试的装置,包括水喷射装置、层流流动装置、环向流动装置、径向流动装置以及湍流流动装置,介绍了各套装置的应用以及优缺点。     

2,4,6-三甲基苯乙酸的合成新方法

以2,4,6-三甲基苯甲醛为原料,通过相转移催化反应在水-氯仿体系中先合成α-羟基-2,4,6-三甲基苯乙酸(收率52%);再通过次磷酸还原α-羟基-2,4,6-三甲基苯乙酸得到最终产物2,4,6-三甲基苯乙酸(收率91%)。此法绿色便捷,成本相对较低。     

红曲与红曲色素的研究进展

阐述了红曲与红曲色素的各类，生产工艺及应用，介绍了红曲与红曲色素的现状和市场开发前景。     

磷酸硼对樟子松的阻燃影响

采用磷酸硼对木材进行改性处理,测定了处理后试材的阻燃性、抗流失性、吸湿性、力学性能.研究结果表明,磷酸硼处理后试材,吸药量达到20.47 kg/m3以上时,垂直燃烧实验可达到到F-0级水平;通过灼烧实验,磷酸硼处理的木粉在500℃灼烧时残留率可达到97.997％;此改性剂具有较好阻燃性能和一定的抗流失性,常压下磷酸硼处理的樟子松试件LRV为50.28％;木材顺纹抗压强度平均下降了 8.67％,无明显变化;木材抗弯曲压强度平均下降了 27.95％.但磷酸硼阻燃剂在高湿条件下有一定的吸湿性,使用性能有待改进,并应注意采取防护措施.     

载锌NaY分子筛对FCC汽油吸附脱硫性能的影响

采用液相离子交换法将锌离子负载到NaY分子筛上,得到ZnY分子筛脱硫吸附剂。考察了锌离子负载浓度和不同焙烧温度对ZnY分子筛吸附脱硫性能的影响。研究脱硫实验中吸附温度和吸附空速对FCC汽油脱硫性能的影响,样品中的硫含量通过微库仑综合分析仪进行测定。结果表明,Zn(NO₃)₂负载浓度0.30 mol·L^-1、焙烧温度500 ℃、吸附温度30 ℃和吸附空速0.5 h^-1条件下对吸附脱硫性能最有利,脱硫率超过80%。考察两种方法对吸附剂进行再生。     

稀土与L-酪氨酸甘氨酸三元固态配合物的合成与表征

在乙醇溶液中合成了四种稀土与 L-酪氨酸、甘氨酸的三元固态配合物 RE( Tyr) 1.5 ( Gly) 4 ( Cl O4) 3( RE=La3+、Ce3+、Gd3+、Y3+) ,并通过摩尔电导、热分析、红外光谱等进行了表征。     

加氢工艺技术生产25#变压器油

以江苏常二线油为原料,通过加氢微型试验装置,筛选出加氢精制催化剂3996、FV-1,将上述2种催化剂按照1：1（体积比）进行组合装填,进行一段加氢法生产25^#变压器油试验取得成功,并经过了工业生产试运行。结果表明,在适宜的操作条件下,可以利用原白油加氢装置生产出合格的25^#变压器油产品,优化了装置产品结构,提高了装置创效能力。     

TiO2/α-Fe2O3复合光催化剂的制备及表征

用溶胶-凝胶法在α-FeOOH上负载TiO2,经过煅烧制备了TiO2/α-Fe2O3光催化剂.用Brunauer-Emmett-Teller(BET)法测试氮吸附比表面积.用X射线衍射、透射电镜、扫描电镜、Fourier转换红外光谱等研究了不同煅烧温度制备的光催化剂物相组成和形貌特征.研究了不同煅烧温度制备的光催化剂对活性艳蓝X-BR染料的吸附和光催化性能.结果表明:与未负载TiO2的α-FeOOH相比,经过复合、350℃煅烧制备的TiO2/α-Fe2O3复合材料的比表面积有了显著增加,从35.4m2/g增加到167.7m2/g,但是,当温度高于450℃时,其比表面积又有所下降.随着煅烧温度的增加,其负载的TiO2晶型由锐钛矿转变为金红石型,粒径也逐渐增大.在煅烧温度为350℃时,TiO2/α-Fe2O3催化剂吸附和光催化性能最好,脱色率可达到85.19%.