The tautomerization of H2NCH2C(OH)NH to H2NCH2CONH2 is an important step by way of Strecker synthesis for the production of glycine in the interstellar medium (ISM) with respect to the origin of amino acids on the ear...The tautomerization of H2NCH2C(OH)NH to H2NCH2CONH2 is an important step by way of Strecker synthesis for the production of glycine in the interstellar medium (ISM) with respect to the origin of amino acids on the early Earth.Our work indicates two mechanisms for the tautomerization to occur.k CVT/SCT (rate constant) is 45.6s-1 at 50 K,obtained with the small curvature tunneling (SCT) approximation and canonical variational transition state theory (CVT),to support one mechanism assisted by quantum tunneling in the ISM.Another mechanism is through the (H2O) 2-coupled proton transfer.In the (H2O)2 coupled reaction,two H2O molecules act as a catalyst to reduce the barrier energy by 23.7 kcal mol 1,and cooperatively let a proton pass a hydrogen-bonded bridge composed of H2NCH2C(OH)NH with (H2O)2.kTST is 8.08×10-4 s-1 at 100 K,calculated with TST kinetics,to demonstrate the mechanism.Therefore,the tautomerization is feasible in the ISM.H2NCH2C(OH)NH and H2NCH2CONH2 will be detected in the ISM and found in carbonaceous chondrites.The results present new evidence for the third theory on the origin of amino acids on the early Earth.展开更多
文摘目的探讨CARTOSound引导下射频消融对肥厚型梗阻性心肌病患者的临床疗效。方法连续入选2019年6-12月在本院心血管内科就诊的经超声心动图证实存在收缩期二尖瓣前叶前向运动(systolic anterior motion,SAM)现象的肥厚型梗阻性心肌病患者,就其临床特征、消融策略及消融效果进行回顾性分析。根据消融效果不同分为反应组和非反应组,分析影响消融效果的因素。结果共入选11例,其中男性3例,女性8例,年龄44~77(58.36±10.82)岁,病史6个月至2年,患者经消融后腔内即刻静息跨左心室流出道压力阶差(20.00±31.12 mmHg vs 57.09±33.44 mmHg,P=0.01)及早搏刺激后跨左心室流出道压力阶差(24.09±19.34 mmHg vs 139.60±44.52 mmHg,P<0.01)均明显下降,随访3个月后心脏超声提示室间隔厚度(18.15±92.84 mm)较术前无明显差异(19.50±2.67 mm,P=0.35),跨左心室流出道压力阶差较术前有所下降,但无统计学差异(71.09±31.40 mmHg vs 52.38±35.76 mmHg,P=0.28),术后6个月随访结果相似,但患者NYHA明显改善(1.64±0.15 vs 2.36±0.20,P<0.01)。与非反应组(5例)比较,反应组(6例)患者有室间隔厚度更薄、左心室直径更小、BNP更低的趋势。结论CARTOsound引导下射频消融治疗肥厚型梗阻性心肌病患者可改善心功能,短期内可缓解左心室流出道梗阻。
基金supported by the One-Hundred-Talents Project of Chinese Academy of Sciences,and the Academic Talent Foundation of Yunnan Province,China (Grant No.2006PY01-29)
文摘The tautomerization of H2NCH2C(OH)NH to H2NCH2CONH2 is an important step by way of Strecker synthesis for the production of glycine in the interstellar medium (ISM) with respect to the origin of amino acids on the early Earth.Our work indicates two mechanisms for the tautomerization to occur.k CVT/SCT (rate constant) is 45.6s-1 at 50 K,obtained with the small curvature tunneling (SCT) approximation and canonical variational transition state theory (CVT),to support one mechanism assisted by quantum tunneling in the ISM.Another mechanism is through the (H2O) 2-coupled proton transfer.In the (H2O)2 coupled reaction,two H2O molecules act as a catalyst to reduce the barrier energy by 23.7 kcal mol 1,and cooperatively let a proton pass a hydrogen-bonded bridge composed of H2NCH2C(OH)NH with (H2O)2.kTST is 8.08×10-4 s-1 at 100 K,calculated with TST kinetics,to demonstrate the mechanism.Therefore,the tautomerization is feasible in the ISM.H2NCH2C(OH)NH and H2NCH2CONH2 will be detected in the ISM and found in carbonaceous chondrites.The results present new evidence for the third theory on the origin of amino acids on the early Earth.
