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The author's previous work indicated that the activity of granular fused iron catalysts decreased seriously with time due to the gradual plugging up of the pore volume of catalysts by the high boiling point products. In this paper, the activity data were treated with Wheeler's internal diffusion law mathematically. And the results suggest that the rate is a chemical controlling one in the initial period of the synthesis, and the coefficient of the catalysts surface is of 0.98 (with space velocity 1000 hr~(-1),... The author's previous work indicated that the activity of granular fused iron catalysts decreased seriously with time due to the gradual plugging up of the pore volume of catalysts by the high boiling point products. In this paper, the activity data were treated with Wheeler's internal diffusion law mathematically. And the results suggest that the rate is a chemical controlling one in the initial period of the synthesis, and the coefficient of the catalysts surface is of 0.98 (with space velocity 1000 hr~(-1), CO conversion 90% or so). When the catalysts pore volume are plugged up by the high boiling point products (whether the pore to be micro or macro), the rate becomes an internal diffusion controlling one, and the effectiveness of the catalytic surface changed into 0.082. The calculated coefficient of diffusion is of 2.4 10~(-5) cm~2/sec, which is in agreement with the magnitude of liquid-phase diffusion. Under the diffusional controlling conditions, the activity level of catalysts depends upon Deff, ks and Sg, by the rate law k∝2~(1/Deff·ks·Sg.) Where change of effective diffusivity. Deff, under the liquid phase conditions is not essential. But both the specific reaction rate, ks, and the effective surface, Sg are the major factors to the catalytic activity improvements. Therefore the precipited iron catalysts, owing to its high specific surface area and high specific activity, may be the promising one of the granular catalysts suitable for the high space velocity synthesis. 已往的工作指出,顆粒熔鉄催化剂在合成过程中活性有随时間下降的現象,认为主要是由于腊液堵塞孔隙的关系,应用成型方法构成大孔,能够有利于腊液的流出,延緩了活性下降的时間,但当腊液堵滿孔隙时,活性下降的水平仍与未成型的顆粒催化剂相近。本文根据活性方面的数据,进行了宏观动力学的分析,由动力学計算再次指明:当腊液未堵塞孔隙吋,合成反应是化学反应控制,此时表面有效利用系数达0.98(空速1000,CO轉化90%以上)。而当腊液堵塞孔隙后,轉为液相扩散控制,对362-1大顆粒催化剂言,此时表面有效利用系数为0.082,并求得气体通过液柱的扩散系数为2.4×10~(-5)厘米~2/秒。在扩散控制的情况下,由动力学分析指明,能影响活性水平的主要是Deff、Ks、Sg。有效扩散系数Deff在液相扩散情况下的改变是不大的,增大孔径并不能提高扩散控制时的活性水平。因此,孔径的增大在合成烃情况下仅起延緩腊液的积聚作用,而不能提高終活性的水平。由动力学分析指出,沉淀剂由于有大的表面积(較熔鉄剂大数倍以至数十倍),因此,可能适用于高速固定床操作而不須进行再生。实驗也驗証了这个看法。 The direct detection of plasma angiotensin Ⅱ (AT Ⅱ) by radioimmunoassay with 0.5ml of human blood was aohieved by utilizing fine-quality antisera, ~(125)I. AT Ⅱ of high specific activity and the double antisera separation technique. 应用优质抗血清、高比放射度~(125)I·ATII及双抗体分离技术,建立了直接测定0.5毫升人血浆中血管紧张系Ⅱ(ATII)的放射免疫分析法。竞争抑制曲线的最小检出量3.6±1.6微微克,精密度4.7±1.4%(28次的m±S.D.)。血浆测定的变异系数为批内7~14%,批间8.7~18%。加入血浆中的ATII可定量回收(97~117%)。随待测血浆加入量增大(0.1至1.5毫升/孵育管),测得ATII量线性增加。8种肽类激素、人血浆及使用的酶抑制剂未显示出明显的干扰。正常人普通饮食时外周静脉血浆ATII浓度:卧位1.5小时以上后26±10微微克/毫升(n=54),与24小时尿钠排出量呈负相关(p<0.01);立位2小时后46±22微微克/毫升(n=17)。低钠饮食或肌肉注射速尿引起血浆中ATII显著激发(p<0.01)。本法可灵敏、精密、特异地正确度量微量ATII,操作简单,每批可测标本数较大。本法的建立有助于各领域中涉及肾素——血管紧张素系统之临床或实验研究工作。 The ~(14)C-labeled gossypol acetic acid (Sp.Act.2.665μci/mg) used in this experiment and the care and trea-tment of animals were the same asthe previous report.Wistar adult malerats selected for uniformity of weight(about 200g) were placed in individu-al metabolic cages,the feces,urine andexpired air were collected daily formeasurement in one group of animalsfollowing a single oral dose (20μci/7.5 mg) of ~(14)C-gossypol,acetie acid.The animals were anesthetized and kil-led after varying intervals of time (i.e.12... The ~(14)C-labeled gossypol acetic acid (Sp.Act.2.665μci/mg) used in this experiment and the care and trea-tment of animals were the same asthe previous report.Wistar adult malerats selected for uniformity of weight(about 200g) were placed in individu-al metabolic cages,the feces,urine andexpired air were collected daily formeasurement in one group of animalsfollowing a single oral dose (20μci/7.5 mg) of ~(14)C-gossypol,acetie acid.The animals were anesthetized and kil-led after varying intervals of time (i.e.12 hours,1,2,4,9 and 14 days,3animals for each time).The bloodwas collected and various organ tis-sues as well as the contents of gastro-intestinal tract were removed,lyophili-zed and weighed ground for liquidscintillation counting by oxygen com-bustion.The free and bound gossypolwere extracted from parts of the aboveorgans,and an analysis of the ratioChanges of the free to bound gossypol(F/B) in the metabolic process wasmade.To the daily dose group,therats were given labeled gossypol atthe dosage of 4.5μci/5 mg daily and were anesthetized and killed 2 weeks,3 weeks,one and two weeks following the withdrawal of the drug (2 animalsfor each time period).Samples of tis-sues and excreta were prepared formeasurement according to the proce-dures as described above.The resultsobtained were summarized as follows.1.It was found that the injected~(14)C-labeled gossypol excreted rapidlythrough feces,urine and expired airfollowing the oral administration.Themain pathway of excretion was fromthe feces,followed by exhaled CO_2 andurine.The amount of ~(14)C eliminated in19 days was 83.50% in feces,11.73%in expired CO_2 and 2.51% in urine. The high excretion rate in feces sug-gested that the circulation and me-tabolism of gossypol through liver-bile-feces were the main pathway of elim-ination and detoxication of the gos-sypol from the body.The exhaledCO_2 appeared to be a metabolic pro-ducts of decarbonylation of formyl-~(14)C-gossypol,and thus,the decarbo-nylation is also one of the pathway ofelimination and dtoxication of gossypol.The low gossypol excretion in urine might be related to their nonionized large molecules of gossypol which were uneasied to pass through the renal glomeruli but were more favored toreabsorption by the renal tubules.2.After a single oral dose of~(14)C-labeled gossypol to male rats at thedosage of 2oμci/7.5mg/animal,thetime taken for the elimination fromthe body of one half of the radioac-tivity was 60 hours (i.e.t1/2=2.5days).According to this half-life valueof excretion,it was possible to cal-culate that the time for the clearanceof gossypol from the body would beat the 23rd day or nearly so,it wasmostly corresponding to our data thatit took 19 days to eliminate 97.74%of the dose from the animal body.3.The data obtained by radioac-tivity measurement of the tissues fromrats fed ~(14)C-labeled gossypol demon-strated that the contents and the epi-thelial lining of gastro-intestinal tractand the liver had the highest specificradioactivity.They reached their peaklevels one day following a single oral dosing.The blood also reached its peak at the first day,however,its specific activity was lower than that of the above visceral organs.The specific radioactivity in the heart,kidney,sple-en,lung,pancreas,diaphragm andtestis were low at the early stages ofdrug adiministration,but rapidly rea-ched to their peak at the 4—9th day.Among the organs,the spleen,kidneyand heart contained more higher speci-fic activity than that of other organs.The endocrine organs such as adrenal,pituitary and thyroid gland also con-tained a fairly high specific activity.Whereas,the hypothalamus,medullaoblongata and spinal cord had the lo-west activity only.The specific acti-vity in various organs decreased ingeneral with the increase of time dura-tion,and dropped to their minimumamount 19 days after the administra-tion.4.The pharmacokinetics of ~(14)C-gossypol in rats that on daily dosingwere almost the same as in the rats ofsingle oral dosing group.Two weeksfollowing the administration,all tis-sues contained radioactivity,with the brain having the lowest activity.The contents and tissues of alimentary canal as well as liver had the highest specific acitivity also,followed by spleen,kidney,heart,lung pancrease,diaphragm and testis.They reached their peak levels after 3 weeks of daily dosing.But thereafter,the specific acitivitysteadily decreased to a lower level.Two weeks after the withdrawal oftreatment,the activity in various tis-sues decreased to their minimum am-ounts.These reaults indicated thatthe pharmacokinetics of ~(14)C-gossypolin both dosage groups were basicallysimilar in distribution pattern,and thedata of quantitative measurement andautoradiographic investigation werecoincided with each other either.5.The results demonstrated thatthe ratios of free gossypol (F) to boundgossypol (B) in the contents and tissuesof different parts of the gastro-intes-tinal tract,liver,and feces were lowat the early stages of drug administr-ation.However,the value of theseratios had progressively increased withtime in both dosing grops.These data suggested that the gossypol might mainly metabolized as a binding form during early stages of medication within rat body.Subsequently,the proportion of free gossypol and other metabolites increased with time throughoxidation,hydrolysis and decarbonyla-tion of the bound gossypol in varioustissues,resulting in soluble or air formand cxcreted via feces,urine and expir-ed air. 1.大鼠口服标记棉酚后迅速通过粪、尿和呼气排出。粪排出量最多,占口服总剂量的83.5%;其次为呼气中的~(14)CO_2,占11.73%;尿中的含量最少,只占2.51%。经粪排出率最高,表明通过肝脏—胆汁—粪的代谢和排泄是排除体棉酚的主要途径和解毒过程。呼气中的CO_2是棉酚代谢过程中脱羰基作用的产物,这一过程也是体内棉酚解毒过程的一种方式。尿中排泄量低,可能与棉酚的非离子化态大分子结构不易通透肾小球而有利于肾小管的重吸收有关。2.大鼠一次口服标记棉酚20微居里/7.5毫克后,从体内排出总剂量的半量的时间(t(1/2))为2.5天,按排泄半量规律推算,从体内清除所需的时间约为服药后的第23天左右,与我们在第19天实测的体内残留率比例大体相符。3.分布于脏器组织中的标记棉酚的定量测定结果表明:胃、肠道内容物,胃、肠道组织和肝脏中的比活性最高,在服药后1天即到达它们的高峰强度水平。血液的活性在1天内亦到达高峰。但其比活性较上述脏器组织为低。心、肾、脾、肺、胰、膈肌和睾丸等主要脏器组织的比活性在服药后的初期较低。到第4天才达到它们各自的高峰水平。其中脾、肾、心的比活性较其他脏器为高,内分泌腺中的肾上腺、垂体和甲状腺... 1.大鼠口服标记棉酚后迅速通过粪、尿和呼气排出。粪排出量最多,占口服总剂量的83.5%;其次为呼气中的~(14)CO_2,占11.73%;尿中的含量最少,只占2.51%。经粪排出率最高,表明通过肝脏—胆汁—粪的代谢和排泄是排除体棉酚的主要途径和解毒过程。呼气中的CO_2是棉酚代谢过程中脱羰基作用的产物,这一过程也是体内棉酚解毒过程的一种方式。尿中排泄量低,可能与棉酚的非离子化态大分子结构不易通透肾小球而有利于肾小管的重吸收有关。2.大鼠一次口服标记棉酚20微居里/7.5毫克后,从体内排出总剂量的半量的时间(t(1/2))为2.5天,按排泄半量规律推算,从体内清除所需的时间约为服药后的第23天左右,与我们在第19天实测的体内残留率比例大体相符。3.分布于脏器组织中的标记棉酚的定量测定结果表明:胃、肠道内容物,胃、肠道组织和肝脏中的比活性最高,在服药后1天即到达它们的高峰强度水平。血液的活性在1天内亦到达高峰。但其比活性较上述脏器组织为低。心、肾、脾、肺、胰、膈肌和睾丸等主要脏器组织的比活性在服药后的初期较低。到第4天才达到它们各自的高峰水平。其中脾、肾、心的比活性较其他脏器为高,内分泌腺中的肾上腺、垂体和甲状腺的比活性亦较高。而神经系统中的丘脑下部、延脑和脊髓的比活性则均较低。各脏器的比活性随时间而递减下降,到第19天后均下降至微量水平。4.连续给药组脏器组织中的标记棉酚分布动态与上述一次给药组基本相同。连续每日服药2周后,所有组织均出现放射活性,其中脑组织的比活性最低,胃、肠道壁及其内容物以及肝的比活性最高。其次为脾、肺、心、肾、胰、膈肌和睾丸。这些主要脏器在连续服药3周后达到各自的比活性高峰水平。以后即逐渐下降。停药2周后均下降至微量水平。上述结果表明两个给药组的棉酚分布的变化动态基本一致,定质和定位的结果亦基本相符。5.棉酚的代谢:两个服药剂量组的胃、肠道组织,肝组织,胃、肠道内容物和粪中的游离棉酚(F)和结合棉酚(B)的比值,在服药后的初期均较小。以后随时间而逐渐递增。反映了棉酚在体内的早期代谢形式以结合棉酚为主,以后在脏器组织中通过氧化、分解或转化,游离棉酚及其代谢产物的比例增加,通过粪、尿和呼气(脱羰基后的CO_2)排出。
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