As an effective non-petroleum based process for producing light olefins, the methanol-to-olefin(MTO) route has become an indispensable alternative to the industrial production of light olefins. The silicoaluminophosph...As an effective non-petroleum based process for producing light olefins, the methanol-to-olefin(MTO) route has become an indispensable alternative to the industrial production of light olefins. The silicoaluminophosphate SAPO-34 zeolite(CHA-type structure) has proven to be an efficient industrial catalyst for the production of ethylene and propylene by the MTO reaction. However, the inherent structure and related diffusion limitations of SAPO-34 limit the mass transport and thus cause rapid deactivation of the catalyst. Fabrication of hierarchical SAPO-34 zeolite is one of the most effective strategies to address the intrinsic diffusion limitation. As simple, inexpensive, and efficient approach, the post-synthetic route has attracted considerable attention and widely used to introduce secondary meso-/macropores into the microporous SAPO-34 material. Significant effort has been dedicated to the development of post-synthesis strategies to prepare hierarchical SAPO-34 zeolite, thereby enhancing its catalytic performance in the MTO process. This mini-review addresses the post-synthesis preparation of hierarchical SAPO-34 catalysts and their MTO performance. Furthermore, some current problems and prospects of the post-synthesis route to hierarchical SAPO-34 catalysts are also revised. We expect this minireview to inspire the more efficient preparation of hierarchical SAPO-34 catalysts for the MTO process.展开更多
With the increasingly stringent standards for limiting sulfide content in liquid fuels,oxidative desulfurization(ODS)has become a promising ultra-deep desulfurization process in fuel desulfurization.TS-1 zeolites show...With the increasingly stringent standards for limiting sulfide content in liquid fuels,oxidative desulfurization(ODS)has become a promising ultra-deep desulfurization process in fuel desulfurization.TS-1 zeolites show great potential as catalysts for ODS reactions,due to its remarkable oxidation activity at low temperatures and pressure.However,the inherent microporous structure of conventional TS-1 zeolites restricts the mass transportation and renders the active sites in the microporous space of TS-1 zeolites inaccessible for bulky aromatic organosulfur compounds.Fabrication of hierarchical TS-1 zeolites by incorporating meso-/macropores into microporous TS-1 zeolites is an effective strategy to improve mass transportability.In recent years,abundant efforts have been dedicated to developing synthetic strategies of hierarchical TS-1 zeolite,thereby improving its catalytic performance in the ODS process.This mini-review addresses the synthetic methods of hierarchical TS-1 catalysts and their catalytic performance in the ODS reactions.In addition,some current problems and prospects of synthesis routes for constructing hierarchical TS-1 catalysts have also been revised.We expect this mini-review to shed light on the more efficient preparation strategies of hierarchical TS-1 zeolites for the ODS process.展开更多
Many people around the world have lost their lives due to COVID-19.The symptoms of most COVID-19 patients are fever,tiredness and dry cough,and the disease can easily spread to those around them.If the infected people...Many people around the world have lost their lives due to COVID-19.The symptoms of most COVID-19 patients are fever,tiredness and dry cough,and the disease can easily spread to those around them.If the infected people can be detected early,this will help local authorities control the speed of the virus,and the infected can also be treated in time.We proposed a six-layer convolutional neural network combined with max pooling,batch normalization and Adam algorithm to improve the detection effect of COVID-19 patients.In the 10-fold cross-validation methods,our method is superior to several state-of-the-art methods.In addition,we use Grad-CAM technology to realize heat map visualization to observe the process of model training and detection.展开更多
Purpose: To study the clinical features, diagnosis and management of intraosseous cavernous hemangioma of the orbit.Methods: Five cases of intraosseous cavernous hemangioma seen in our hospital from Jan 1, 1986 to Dec...Purpose: To study the clinical features, diagnosis and management of intraosseous cavernous hemangioma of the orbit.Methods: Five cases of intraosseous cavernous hemangioma seen in our hospital from Jan 1, 1986 to Dec 31, 2000 were reviewed.Results: Among all five cases, two were male and three were female. The mean age was 47.6 years old, ranging from 39.0 to 55.0 years. The left orbit was affected in 4 cases and the right one in 1 case. The bony involvement occurred in frontal bone (two cases),zygomatic bone (two cases) and sphenoid bone (one case). A painless, slowly enlarging hard bony mass fixed to the bone with no pulsations was the main clinical sign. The x-ray and CT appearance of intraosseous cavernous hemangioma of the orbit were characteristic and usually diagnostic. The differential diagnosis of it included fibrous dysplasia,eosinophilic granuloma, multiple myeloma and metastatic carcinoma. Treatment is local removal of the bone containing the tumor.Conclusions: Intraosseous cavernous hemangioma is a rare tumor of the orbit and usually has good surgical result.展开更多
基金supported by the National Natural Science Foundation of China(21971082)the Jilin Province Science and Technology Development Plan(20190201229JC and 20200201096JC)+1 种基金the China Postdoctoral Science Foundation(2018M640280 and 2019T120235)for supporting this workthe National 111 Project(B17020)。
文摘As an effective non-petroleum based process for producing light olefins, the methanol-to-olefin(MTO) route has become an indispensable alternative to the industrial production of light olefins. The silicoaluminophosphate SAPO-34 zeolite(CHA-type structure) has proven to be an efficient industrial catalyst for the production of ethylene and propylene by the MTO reaction. However, the inherent structure and related diffusion limitations of SAPO-34 limit the mass transport and thus cause rapid deactivation of the catalyst. Fabrication of hierarchical SAPO-34 zeolite is one of the most effective strategies to address the intrinsic diffusion limitation. As simple, inexpensive, and efficient approach, the post-synthetic route has attracted considerable attention and widely used to introduce secondary meso-/macropores into the microporous SAPO-34 material. Significant effort has been dedicated to the development of post-synthesis strategies to prepare hierarchical SAPO-34 zeolite, thereby enhancing its catalytic performance in the MTO process. This mini-review addresses the post-synthesis preparation of hierarchical SAPO-34 catalysts and their MTO performance. Furthermore, some current problems and prospects of the post-synthesis route to hierarchical SAPO-34 catalysts are also revised. We expect this minireview to inspire the more efficient preparation of hierarchical SAPO-34 catalysts for the MTO process.
基金supported by the National Natural Science Foundation of China(21971082)the Jilin Province Science and Technology Development Plan(20200201096JC and 20190201229JC)+1 种基金the China Postdoctoral Science Foundation(2019T120235 and 2018M640280)for supporting this workthe 111 Project(B17020)。
文摘With the increasingly stringent standards for limiting sulfide content in liquid fuels,oxidative desulfurization(ODS)has become a promising ultra-deep desulfurization process in fuel desulfurization.TS-1 zeolites show great potential as catalysts for ODS reactions,due to its remarkable oxidation activity at low temperatures and pressure.However,the inherent microporous structure of conventional TS-1 zeolites restricts the mass transportation and renders the active sites in the microporous space of TS-1 zeolites inaccessible for bulky aromatic organosulfur compounds.Fabrication of hierarchical TS-1 zeolites by incorporating meso-/macropores into microporous TS-1 zeolites is an effective strategy to improve mass transportability.In recent years,abundant efforts have been dedicated to developing synthetic strategies of hierarchical TS-1 zeolite,thereby improving its catalytic performance in the ODS process.This mini-review addresses the synthetic methods of hierarchical TS-1 catalysts and their catalytic performance in the ODS reactions.In addition,some current problems and prospects of synthesis routes for constructing hierarchical TS-1 catalysts have also been revised.We expect this mini-review to shed light on the more efficient preparation strategies of hierarchical TS-1 zeolites for the ODS process.
文摘Many people around the world have lost their lives due to COVID-19.The symptoms of most COVID-19 patients are fever,tiredness and dry cough,and the disease can easily spread to those around them.If the infected people can be detected early,this will help local authorities control the speed of the virus,and the infected can also be treated in time.We proposed a six-layer convolutional neural network combined with max pooling,batch normalization and Adam algorithm to improve the detection effect of COVID-19 patients.In the 10-fold cross-validation methods,our method is superior to several state-of-the-art methods.In addition,we use Grad-CAM technology to realize heat map visualization to observe the process of model training and detection.
基金The paper was sponsored by the natural science foundation of Guangzhou Province. (No.036651)
文摘Purpose: To study the clinical features, diagnosis and management of intraosseous cavernous hemangioma of the orbit.Methods: Five cases of intraosseous cavernous hemangioma seen in our hospital from Jan 1, 1986 to Dec 31, 2000 were reviewed.Results: Among all five cases, two were male and three were female. The mean age was 47.6 years old, ranging from 39.0 to 55.0 years. The left orbit was affected in 4 cases and the right one in 1 case. The bony involvement occurred in frontal bone (two cases),zygomatic bone (two cases) and sphenoid bone (one case). A painless, slowly enlarging hard bony mass fixed to the bone with no pulsations was the main clinical sign. The x-ray and CT appearance of intraosseous cavernous hemangioma of the orbit were characteristic and usually diagnostic. The differential diagnosis of it included fibrous dysplasia,eosinophilic granuloma, multiple myeloma and metastatic carcinoma. Treatment is local removal of the bone containing the tumor.Conclusions: Intraosseous cavernous hemangioma is a rare tumor of the orbit and usually has good surgical result.
