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1.
汽油添加剂甲基叔丁基醚的毒性研究   总被引:1,自引:1,他引:0  
目的 通过研究汽油添加剂甲基叔丁基醚 (MTBE)对小鼠体内谷胱甘肽 (GSH)、谷胱甘肽过氧化物酶 (GSH -Px)活性的改变以及骨髓微核、精子畸变率的影响 ,了解汽油添加剂甲基叔丁基醚的毒性。方法  40只健康昆明种成年小鼠 ,体重 3 3 .3± 6 .9g ,随机分为 4组。灌胃染毒 ,染毒剂量分别为1 6 0 0、40 0、1 0 0和 0mg kg。每天 1次 ,每周 5天 ,共计 40天。结果 MTBE染毒各组小鼠体重轻度降低 ,染毒组全血及肝组织匀浆中GSH在低剂量染毒时增高 ,而高剂量时表现为降低 ,与对照组比较差异有显著性 (P <0 .0 5 ) ;GSH -Px活性明显减低 ,染毒高剂量组与对照组比较差异有高度显著性 (P <0 .0 1 ) ;骨髓嗜多染红细胞微核及精子畸变率增高 ,与对照组比较明显增高 ,差异有显著性 (P <0 .0 5 )。结论 MTBE对昆明小鼠具有一定毒性 ,可降低全血及肝脏组织中GSH -Px活性 ,低剂量时可增加全血及肝脏组织中GSH含量 ,而高剂量可降低其含量。MTBE能使骨髓微核率、精子畸形率明显增高 ,提示MTBE具有潜在的遗传毒性。  相似文献   
2.
通过溴化聚苯醚和格利雅试剂反应,将不饱和基团烯丙基引入聚苯醚中实现其热固性改性,由^1H-NMR和FTIR进行结构表征。确定了烯丙化聚苯醚的固化工艺,并对其固化产物性能进行测试。结果表明:按合成新工艺制备的热固性聚苯醚,其固化产物具有优异的介电性能(低介电常数、低介电损耗因子),良好的耐溶剂性能和低吸湿性。  相似文献   
3.
目的 分析国产光敏剂血卟啉单甲醚(HMME)在不同溶液中光漂白反应动力学规律,加深对光漂白反应复杂反应过程的理解,并为HMME-PDT治疗微血管病变的数学建模研究提供实验依据和参数。 方法 根据光化学反应动力学原理,从理论上推导出在单纯溶液和复杂溶液(含可被光氧化的底物)中,单态氧介导的光漂白反应动力学方程,通过对实验测定的漂白数据(不同时间点的HMME浓度)进行拟合,进一步验证理论推导出光漂白反应动力学方程。 结果 HMME在单一溶液体系(PBS、DMSO)中的光漂白符合1级反应动力学过程,在含底物的复杂体系(白蛋白缓冲液、细胞悬液)中符合2级反应动力学过程。 结论 HMME在不同溶液体系中的光漂白遵循不同的反应动力学规律。根据化学反应动力学原理进行光漂白等复杂光化学反应过程的数学模拟是可行的,并有利于对复杂光化学反应过程的深入理解。  相似文献   
4.
甲基叔丁基醚无铅汽油肾脏毒性的实验研究   总被引:6,自引:0,他引:6  
目的:了解甲基叔丁基醚(MTBE)无铅汽油对肾脏的毒性及毒作用机制。方法:昆明种小鼠经呼吸道静式染毒,MTBE无铅汽油22.9、11.4及2.3g/m^3每天一次,连续2h,共22d亚急性染毒。日立-7150型全自动生化仪检测血清中尿素氮(BUN)、肌酐(Cr)含量;肾组织均浆中丙二醛(MDA)和超氧化物歧化酶(SOD)含量分别用荧光法,邻苯三酚自氧化固定时间法测定;电镜观察肾皮质区超微结构的变化,结果:22.9g/m^3染毒组雌性小鼠血清中BUN含量与阴性对照组间比较差异有显著性(P<0.05);电镜观察到22.9g/m^3染色毒对照组雌雄性小鼠的肾小球基底膜,肾小管细胞线粒体及绒毛均未见显著异常改变。结论:MTBE无铅汽油对肾小球的滤过功能有一定的影响,雌性小鼠可能更为敏感。  相似文献   
5.
To determine the rate and characteristics of gallstone recurrence after direct contact dissolution with methyltert-butyl ether, 60 consecutive patients were followed for up to 4.5 years (median 2.2 years) after complete disappearance of all stone residues and debris and cessation of adjuvant bile acid therapy. Initial gallstones had been multiple in all but four patients. Twenty-eight of the 60 patients developed recurrent gallstones. The cumulative risk of gallstone recurrence (actuarial analysis) was 23±6%, 34±7%, 55±8%, and 70±9% at one, two, three, and four years, respectively. The recurrent stones were usually multiple and small (6±4 mm). Gallstone recurrence was associated with recurrent biliary pain in two patients, one of whom developed acute cholecystitis. Recurrent stones were cleared completely by bile acid medication with or without shock-wave lithotripsy in 61±15% of patients at one year (actuarial analysis). In conclusion, gallstone recurrence after successful contact dissolution of multiple stones with methyltert-butyl ether has to be expected in a high percentage of patients. Most patients, however, remain free of biliary pain during long-term follow-up.  相似文献   
6.
The tissue distribution, metabolism and excretion of 14C-2,2,4,4,5-pentachlorodiphenyl ether (PCDE) were studied in the rat. Radioactivity was distributed in all tissues examined, with the highest concentrations being found in the fat followed by the skin, liver, kidney and muscle. Most of the radioactivity found in the tissues was due to unchanged PCDE. Decay of PCDE in the blood was fitted to a four-compartment pharmacokinetic model, and the last compartment had a half-life of 5.8 days. A total of 55% and 1.3% of an orally administered dose was excreted in feces and urine, respectively, in 7 days. More than 64% of the fecal radioactivity was due to unchanged PCDE, while hydroxylated PCDE accounted for 23%.  相似文献   
7.
The thermo‐adjustable hydrophilic/hydrophobic properties of AB, ABA and BAB block copolymers in which A is poly(methyl vinyl ether) (PMVE) and B is poly(isobutyl vinyl ether) (PIBVE) have been investigated. The block copolymers were prepared by “living” cationic polymerization using sequential addition of monomers. The polymerizations were carried out with the system acetal/trimethylsilyl iodide as initiator and ZnI2 as activator. The initiating system based on diethoxyethane leads to AB block copolymers whereas the initiating system based on tetramethoxypropane leads to ABA or BAB triblock copolymers. Well‐defined block copolymers of different composition with controlled molecular weights up to approx. 10 000 have been prepared. When IBVE is added to living PMVE, PIBVE‐blocks form only in the presence of an additional amount of ZnI2, which is attributed to the fact that part of the ZnI2 is inactive because of complex formation with PMVE. At room temperature, the combination of hydrophilic (PMVE) and hydrophobic (PIBVE) segments provides the copolymers with surfactant properties. Above the lower critical solution temperature (LCST) of PMVE, situated around 36 °C, the PMVE‐blocks become hydrophobic and the amphiphilic nature of the block copolymers is lost. The corresponding changes in hydrophilic/hydrophobic balance have been evaluated by investigation of the emulsifying properties of the block copolymers for water/decane mixtures as a function of the temperature. Below the LCST, the block copolymers have emulsifying properties similar to or better than those of the commercial PEO‐PPO block copolymers (Pluronic®). Either oil‐in‐water or water‐in‐oil emulsions can be obtained, depending on the polymer architecture and the water/decane volume ratio. The emulsifying properties are strongly reduced or completely lost above 40 °C. Emulsions obtained with a PMVE36b‐PIBVE54 block copolymer for a water/decane (v/v) ratio of 85/15 remained stable for more than six months.

50/50 and a 85/15 water/decane w/o emulsion (15 g/l) with the PMVE36b‐PIBVE54 block copolymer at 20 °C.  相似文献   

8.
Calmodulin is an intracellular calcium receptor protein utilized extensively by eukaryotic cells to mediate responsiveness to calcium signals. The present study evaluates the effects on protein structure of amino acid substitutions in trypanosome calmodulin. Calmodulin conformation, hydrophobicity and antigenic determinants are compared among Trypanosoma brucei, Trypanosoma congolense, Trypanosoma vivax, Tetrahymena thermophila and bovine brain. Trypanosome calmodulin differs from brain and Tetrahymena calmodulins based upon isoelectric point, retention time on a C-2/C-18 reverse phase column and interaction with polyclonal antibodies against trypanosome calmodulin by radioimmunoassay or Western procedures. These same analyses do not distinguish trypanosome calmodulins from each other. Polyclonal antibodies against Tetrahymena calmodulin are equally specific and do not recognize the trypanosome or brain calmodulins. Calcium-induced exposure of hydrophobic binding sites are quantitated using the fluorescent probe, N-phenyl-1-naphthylamine. All calmodulins, regardless of source, enhance the fluorescence of N-phenyl-1-naphthylamine 3-4 fold in the presence of calcium. These data demonstrate the extent to which functional calmodulins vary in their structures. We conclude that African trypanosomes share a common calmodulin that is structurally distinct from calmodulin of vertebrates or Tetrahymena.  相似文献   
9.
Summary: Light‐induced reversible changes in elasticity of semi‐interpenetrating network (semi‐IPN) films bearing azobenzene moieties were achieved under both ultraviolet (UV) and visible light irradiation. The semi‐IPN film was prepared by a cationic copolymerization of azobenzene‐containing vinyl ethers in a linear polycarbonate (PC) film as a matrix. When the irradiation was switched on and off, the semi‐IPN film showed rapid reversible deformation with the same behavior occurring over a range of wavelengths, including both the UV and visible regions. The observed reversible deformation of the film was attributed to the decrease in the film's elasticity, which was assumed to be caused by the frequent transcis cycling isomerization of azobenzene moieties taking place during the UV and visible light irradiation. This cycling makes it difficult for the azobenzene groups to aggregate, thus hindering their ability to function as pseudo‐crosslinking points.

  相似文献   

10.
用苯酚、苯酐和水合肼合成了4-(4-羟苯基)-2,3-二氮杂萘酮-1,并与双酚-A和二苯甲酮聚合,得到含双酚-A和杂环结构的聚醚酮聚合物。用FT-IR、^13C-NMR、DSC、TGA和DMA等方法对聚合物进行了表征。结果表明,这种可溶性的非晶态聚合物有较高的Tg和很高的耐热温度,Tg随聚合物的组成不同而变化(158-224℃),5%热失重温度为444-541℃。  相似文献   
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