Single-event microkinetic(SEMK) model of the catalytic cracking of methylcyclohexane admixed with 1-octene over REUSY zeolites at 693 K—753 K in the absence of coke formation is enhanced. To keep consistency with the...Single-event microkinetic(SEMK) model of the catalytic cracking of methylcyclohexane admixed with 1-octene over REUSY zeolites at 693 K—753 K in the absence of coke formation is enhanced. To keep consistency with the wellknown carbenium ion chemistry, hydride transfer forming and consuming allylic carbenium ions in the aromatization of cycloparaffins are further investigated and differentiated. The reversibility of endocyclic β-scission and cyclization reactions is refined by accounting explicitly for the reacting olefins and resulting cycloparaffins in the corresponding thermodynamics. 24 activation energies for the reactions involved in the cracking of cycloparaffins are obtained by the regression of 15 sets of experimental data upon taking the resulting 37 main cracking products, i. e., responses into account. The enhanced SEMK model can adequately describe the catalytic behavior of 37 main products with conversion and temperature.展开更多
The developed SEMK model is used to provide an insight into the contribution of individual reactions in the cracking of methylcyclohexane as well as the site coverage by various carbenium ions. The preferred reaction ...The developed SEMK model is used to provide an insight into the contribution of individual reactions in the cracking of methylcyclohexane as well as the site coverage by various carbenium ions. The preferred reaction pathways for the conversion of methylcyclohexane are hydride transfer reactions followed by PCP-isomerizations, deprotonation and endocyclic β-scission, accounting for 61%, 22% and 12% of its disappearance, respectively, at 693 K and 30% conversion of methylcyclohexane. Protolysis plays a minor role in the cracking of methylcyclohexane. Once cyclic diolefins are formed, all of them can be instantaneously transformed to aromatics, which are easily interconverted via disproportionation. Judging from the carbenium ion concentrations it is evident that, at the investigated operating conditions, less than 5% of the acid sites are covered by carbenium ions, less than 2% of which corresponds to cyclic type species including allylic ones.展开更多
通过有机酸对β分子筛进行脱铝改性,采用XRD,BET,NH3-TPD,FTIR,27Al MAS NMR等手段对酸脱铝β分子筛样品进行表征,以乙基环己烷(ECH)为模型化合物考察环烷烃开环反应的性能。结果表明:随脱铝率的增加,β分子筛的相对结晶度、酸量、比表...通过有机酸对β分子筛进行脱铝改性,采用XRD,BET,NH3-TPD,FTIR,27Al MAS NMR等手段对酸脱铝β分子筛样品进行表征,以乙基环己烷(ECH)为模型化合物考察环烷烃开环反应的性能。结果表明:随脱铝率的增加,β分子筛的相对结晶度、酸量、比表面积等均呈现先增加后降低的趋势;反应活性、丙烯收率及丙烯选择性也出现先增加后降低的趋势,但乙烯收率变化幅度较小,当脱铝率为41.7%时ECH开环反应性能最优。展开更多
【目的】观察地佐辛对妇科腹腔镜手术患者术后疼痛的影响。【方法】选取2012年1月至2014年1月在本院进行腹腔镜下妇科手术的患者108例，采用随机数表法将其分为观察组和对照组，每组54例。观察组：术毕前30-40 min 对其静脉注射0．1 mg...【目的】观察地佐辛对妇科腹腔镜手术患者术后疼痛的影响。【方法】选取2012年1月至2014年1月在本院进行腹腔镜下妇科手术的患者108例，采用随机数表法将其分为观察组和对照组，每组54例。观察组：术毕前30-40 min 对其静脉注射0．1 mg／kg 的地佐辛（生理盐水稀释至10 mL）；对照组：术毕前30-40 min 对其静脉注射同容量的生理盐水。对比两组患者术后不同时间点的视觉模拟评分（VAS）、舒适度（BCS 评分）、镇静效果（Ramsay 评分）、术后不良反应发生情况。【结果】观察组患者术后不同时间点的镇痛和镇静效果及舒适度评分显著优于对照组患者，比较两组间差异具有统计学意义（ P ＜0．05）。观察组患者术后的不良反应发生率显著低于对照组患者，比较两组间差异具有统计学意义（ P ＜0．05）。 【结论】术前使用地佐辛能够有效缓解妇科腹腔镜手术患者术后24 h 内患者的疼痛，具有较好的镇痛和镇静效果，能增加患者术后的舒适度，有效降低术后不良反应的发生率，可在临床上进一步推广应用。展开更多
[目的]探讨右美托咪定(Dex)联合地佐辛在腹腔镜胆囊切除术(LC)中的镇痛效果。[方法]本院收治的LC患者90例,随机分为三组,各30例;Dex组、联合组(Dex复合地佐辛)及对照组。观察三组患者手术时间、丙泊酚用量、苏醒时间及术后不良反应发生...[目的]探讨右美托咪定(Dex)联合地佐辛在腹腔镜胆囊切除术(LC)中的镇痛效果。[方法]本院收治的LC患者90例,随机分为三组,各30例;Dex组、联合组(Dex复合地佐辛)及对照组。观察三组患者手术时间、丙泊酚用量、苏醒时间及术后不良反应发生情况;记录术中不同时刻(术前、气腹后、切胆时、拔喉罩时)心率(HR)及平均动脉压(MAP):比较三组术后疼痛程度(VAS评分)及镇静情况(Ramsay评分)。比较手术前后血糖、皮质醇、去甲肾上腺素(NE)水平c[结果]联合组丙泊酚及舒芬太尼用量低于Dex组及对照组(P<0.05),但三组手术时间、苏醒时间比较差异无显著性(P>0.05)。三组术中及术后不良反应发生率比较差异无显著性(P>0.05)。联合组术后1、6、12、24 h VAS评分均低于对照组和Dex组(P<0.05)。联合组术后1、6h Ramsay评分均较对照组和Dex组高(P<0.05)。三组术前、气腹后、切胆时HR及MAP比较差异无显著性(P>0.05).拔喉罩时.联合组HR及MAP较对照组、Dex低(P<0.05)。手术结束时,联合组血糖、皮质醇、NE低于对照组和Dex组(P<0.05)。[结论]Dex联合地佐辛在LC中的镇痛及镇静效果显著,还可降低应激反应,安全性高。展开更多
基金financial support from the China Scholarship Councilthe Long Term Structural Methusalem Funding by the Flemish Government
文摘Single-event microkinetic(SEMK) model of the catalytic cracking of methylcyclohexane admixed with 1-octene over REUSY zeolites at 693 K—753 K in the absence of coke formation is enhanced. To keep consistency with the wellknown carbenium ion chemistry, hydride transfer forming and consuming allylic carbenium ions in the aromatization of cycloparaffins are further investigated and differentiated. The reversibility of endocyclic β-scission and cyclization reactions is refined by accounting explicitly for the reacting olefins and resulting cycloparaffins in the corresponding thermodynamics. 24 activation energies for the reactions involved in the cracking of cycloparaffins are obtained by the regression of 15 sets of experimental data upon taking the resulting 37 main cracking products, i. e., responses into account. The enhanced SEMK model can adequately describe the catalytic behavior of 37 main products with conversion and temperature.
基金the financial support from the China Scholarship Councilthe Long Term Structural Methusalem Funding by the Flemish Government
文摘The developed SEMK model is used to provide an insight into the contribution of individual reactions in the cracking of methylcyclohexane as well as the site coverage by various carbenium ions. The preferred reaction pathways for the conversion of methylcyclohexane are hydride transfer reactions followed by PCP-isomerizations, deprotonation and endocyclic β-scission, accounting for 61%, 22% and 12% of its disappearance, respectively, at 693 K and 30% conversion of methylcyclohexane. Protolysis plays a minor role in the cracking of methylcyclohexane. Once cyclic diolefins are formed, all of them can be instantaneously transformed to aromatics, which are easily interconverted via disproportionation. Judging from the carbenium ion concentrations it is evident that, at the investigated operating conditions, less than 5% of the acid sites are covered by carbenium ions, less than 2% of which corresponds to cyclic type species including allylic ones.
文摘通过有机酸对β分子筛进行脱铝改性,采用XRD,BET,NH3-TPD,FTIR,27Al MAS NMR等手段对酸脱铝β分子筛样品进行表征,以乙基环己烷(ECH)为模型化合物考察环烷烃开环反应的性能。结果表明:随脱铝率的增加,β分子筛的相对结晶度、酸量、比表面积等均呈现先增加后降低的趋势;反应活性、丙烯收率及丙烯选择性也出现先增加后降低的趋势,但乙烯收率变化幅度较小,当脱铝率为41.7%时ECH开环反应性能最优。
文摘【目的】观察地佐辛对妇科腹腔镜手术患者术后疼痛的影响。【方法】选取2012年1月至2014年1月在本院进行腹腔镜下妇科手术的患者108例，采用随机数表法将其分为观察组和对照组，每组54例。观察组：术毕前30-40 min 对其静脉注射0．1 mg／kg 的地佐辛（生理盐水稀释至10 mL）；对照组：术毕前30-40 min 对其静脉注射同容量的生理盐水。对比两组患者术后不同时间点的视觉模拟评分（VAS）、舒适度（BCS 评分）、镇静效果（Ramsay 评分）、术后不良反应发生情况。【结果】观察组患者术后不同时间点的镇痛和镇静效果及舒适度评分显著优于对照组患者，比较两组间差异具有统计学意义（ P ＜0．05）。观察组患者术后的不良反应发生率显著低于对照组患者，比较两组间差异具有统计学意义（ P ＜0．05）。 【结论】术前使用地佐辛能够有效缓解妇科腹腔镜手术患者术后24 h 内患者的疼痛，具有较好的镇痛和镇静效果，能增加患者术后的舒适度，有效降低术后不良反应的发生率，可在临床上进一步推广应用。
文摘[目的]探讨右美托咪定(Dex)联合地佐辛在腹腔镜胆囊切除术(LC)中的镇痛效果。[方法]本院收治的LC患者90例,随机分为三组,各30例;Dex组、联合组(Dex复合地佐辛)及对照组。观察三组患者手术时间、丙泊酚用量、苏醒时间及术后不良反应发生情况;记录术中不同时刻(术前、气腹后、切胆时、拔喉罩时)心率(HR)及平均动脉压(MAP):比较三组术后疼痛程度(VAS评分)及镇静情况(Ramsay评分)。比较手术前后血糖、皮质醇、去甲肾上腺素(NE)水平c[结果]联合组丙泊酚及舒芬太尼用量低于Dex组及对照组(P<0.05),但三组手术时间、苏醒时间比较差异无显著性(P>0.05)。三组术中及术后不良反应发生率比较差异无显著性(P>0.05)。联合组术后1、6、12、24 h VAS评分均低于对照组和Dex组(P<0.05)。联合组术后1、6h Ramsay评分均较对照组和Dex组高(P<0.05)。三组术前、气腹后、切胆时HR及MAP比较差异无显著性(P>0.05).拔喉罩时.联合组HR及MAP较对照组、Dex低(P<0.05)。手术结束时,联合组血糖、皮质醇、NE低于对照组和Dex组(P<0.05)。[结论]Dex联合地佐辛在LC中的镇痛及镇静效果显著,还可降低应激反应,安全性高。
