Efficient and selective glucose-to-fructose isomerization is a crucial step for production of oxygenated chemicals derived from sugars,which is usually catalyzed by base or Lewis acid heterogeneous catalyst.However,hi...Efficient and selective glucose-to-fructose isomerization is a crucial step for production of oxygenated chemicals derived from sugars,which is usually catalyzed by base or Lewis acid heterogeneous catalyst.However,high yield and selectivity of fructose cannot be simultaneously obtained under mild conditions which hamper the scale of application compared with enzymatic catalysis.Herein,a Li-promoted C_(3)N_(4) catalyst was exploited which afforded an excellent fructose yield(40.3 wt%)and selectivity(99.5%)from glucose in water at 50℃,attributed to the formation of stable Li–N bond to strengthen the basic sites of catalysts.Furthermore,the so-formed N_(6)–Li–H_(2)O active site on Li–C_(3)N_(4) catalyst in aqueous phase changes the local electronic structure and strengthens the deprotonation process during glucose isomerization into fructose.The superior catalytic performance which is comparable to biological pathway suggests promising applications of lithium containing heterogeneous catalyst in biomass refinery.展开更多
The application of ductile rock bolts has been a crucial method for solving the problems of large deformations,energy absorption and stability control issues in deep rock masses.To study the anchoring mechanism of the...The application of ductile rock bolts has been a crucial method for solving the problems of large deformations,energy absorption and stability control issues in deep rock masses.To study the anchoring mechanism of the key expansive structure,this paper proposes a novel type of bolt—the Ductile-Expansion bolt,and conducts research on anchoring mechanics,energy absorption characteristics,and failure modes of the bolt.In addition,this paper defines the concept of load-volume ratio of metal rock bolts and proves the Ductile-Expansion bolt is capable of better improving the unit volume bearing capacity of the bolt material.Furthermore,laboratory and field tests verify the Ductile-Expansion bolt had better anchoring effect than the traditional rebar bolt,with the expansion structure favorably enhancing the ductility and energy absorption performance of the bolt.Finally,this paper microscopically analyzes the crack propagation and distribution morphology of the bolts by establishing a 3D coupled numerical model based on FDM-DEM.Numerical results illustrate the interface at the variable diameter of the Ductile-Expansion bolt serves as the transition zone between high and low stress levels.The expansion structure can impose radial compression on the medium around the bolt,which can improve the bolt anchorage performance.展开更多
基金the National Natural Science Foundation of China(62304252)the Youth Innovation Promotion Association of Chinese Academy Sciences(CAS)and IMECAS-HKUST-Joint Laboratory of Microelectronics。
基金The financial support from the National Natural Science Foundation of China(22278419,21978316,22108289,22172188)the Ministry of Science and Technology of China(2018YFB0604700)Suzhou Key Technology Research(Social Development)Project(2023ss06)。
文摘Efficient and selective glucose-to-fructose isomerization is a crucial step for production of oxygenated chemicals derived from sugars,which is usually catalyzed by base or Lewis acid heterogeneous catalyst.However,high yield and selectivity of fructose cannot be simultaneously obtained under mild conditions which hamper the scale of application compared with enzymatic catalysis.Herein,a Li-promoted C_(3)N_(4) catalyst was exploited which afforded an excellent fructose yield(40.3 wt%)and selectivity(99.5%)from glucose in water at 50℃,attributed to the formation of stable Li–N bond to strengthen the basic sites of catalysts.Furthermore,the so-formed N_(6)–Li–H_(2)O active site on Li–C_(3)N_(4) catalyst in aqueous phase changes the local electronic structure and strengthens the deprotonation process during glucose isomerization into fructose.The superior catalytic performance which is comparable to biological pathway suggests promising applications of lithium containing heterogeneous catalyst in biomass refinery.
基金supported by the National Natural Science Foundation of China(Nos.52174101,52474169,and 42477202)Guangdong Basic and Applied Basic Research Foundation(Nos.2023A1515011634 and 2023A1515030243)the Department of Science and Technology of Guangdong Province,China(No.2021ZT09G087).
文摘The application of ductile rock bolts has been a crucial method for solving the problems of large deformations,energy absorption and stability control issues in deep rock masses.To study the anchoring mechanism of the key expansive structure,this paper proposes a novel type of bolt—the Ductile-Expansion bolt,and conducts research on anchoring mechanics,energy absorption characteristics,and failure modes of the bolt.In addition,this paper defines the concept of load-volume ratio of metal rock bolts and proves the Ductile-Expansion bolt is capable of better improving the unit volume bearing capacity of the bolt material.Furthermore,laboratory and field tests verify the Ductile-Expansion bolt had better anchoring effect than the traditional rebar bolt,with the expansion structure favorably enhancing the ductility and energy absorption performance of the bolt.Finally,this paper microscopically analyzes the crack propagation and distribution morphology of the bolts by establishing a 3D coupled numerical model based on FDM-DEM.Numerical results illustrate the interface at the variable diameter of the Ductile-Expansion bolt serves as the transition zone between high and low stress levels.The expansion structure can impose radial compression on the medium around the bolt,which can improve the bolt anchorage performance.
文摘目的探讨咳喘定穴位贴敷联合小柴胡汤合半夏厚朴汤治疗痰浊阻肺证慢性阻塞性肺疾病(Chronic obstructive pulmonary disease,COPD)患者的临床疗效。方法选取2020年9月—2022年10月期间海南医学院第二附属医院收治的痰浊阻肺证COPD患者144例,按随机数字表法分为西药组、中药组、中药联合贴敷组,每组各48例。西药组采取常规西医治疗,中药组在西药基础上采取小柴胡汤合半夏厚朴汤治疗,中药联合贴敷组在常规西医基础上采取咳喘定穴位贴敷及小柴胡汤合半夏厚朴汤。治疗4周后,观察比较3组患者临床疗效、不良反应发生率、疾病复发率及治疗前后中医证候积分、肺功能[第1秒用力呼气容积(Forced expiratory volume for 1 second,FEV_(1))、用力肺活量(Forced vital capacity,FVC)、FEV_(1)/FVC]、康复效果[慢性阻塞性肺疾病评估测试量表(Chronic obstructive Pulmonary Disease Assessment Test Scale,CAT)、呼吸困难程度评分(modified Medical Research Council,mMRC)、6 min步行距离试验(6 min walking distance test,6MWT)]。结果治疗后中药联合贴敷组总有效率93.75%(45/48)高于西药组77.08%(37/48)、中药组79.17%(38/48),差异有统计学意义(P<0.05)。治疗后3组患者中医证候痰多、喘息、咳嗽、倦怠乏力、腹胀纳呆、下肢水肿积分均较治疗前降低,差异有统计学意义(P<0.05),且中药联合贴敷组中医证候痰多、喘息、咳嗽、倦怠乏力、腹胀纳呆、下肢水肿积分均明显低于西药组、中药组,差异有统计学意义(P<0.05)。治疗后3组患者肺功能FEV_(1)、FVC、FEV_(1)/FVC指标均较治疗前升高,差异有统计学意义(P<0.05);且中药联合贴敷组肺功能FEV_(1)、FVC、FEV_(1)/FVC指标明显高于西药组、中药组,差异有统计学意义(P<0.05)。治疗后3组患者康复效果CAT、mMRC评分较治疗前降低,6MWT较治疗前延长,差异有统计学意义(P<0.05);且中药联合贴敷组康复效果CAT、mMRC评分均明显低于西药组、中药组,6MWT明显优于西药组、中药组,差异有统计学意义(P<0.05)。治疗期间,中药联合贴敷组不良反应发生率8.33%(4/48)与西药组6.25%(3/48)、中药组4.17%(2/48)比较,差异无统计学意义(P>0.05)。治疗6个月后中药联合贴敷组疾病复发率4.17%(2/48)低于西药组18.75%(9/48)、中药组16.67(8/48),差异有统计学意义(P<0.05)。结论联合采取咳喘定穴位贴敷及小柴胡汤合半夏厚朴汤治疗痰浊阻肺证COPD效果显著,可有效缓解患者临床症状,改善肺功能及机体运动耐力,利于提升疾病整体干预效果,降低疾病复发率,且具有安全性。
