The integration of large-scale new energy and high-capacity DC transmission leads to a reduction in system inertia.Grid-forming renewable energy sources(GF-RES)has a significant improvement effect on system inertia.Co...The integration of large-scale new energy and high-capacity DC transmission leads to a reduction in system inertia.Grid-forming renewable energy sources(GF-RES)has a significant improvement effect on system inertia.Commutation failure faults may cause a short-term reactive power surplus at the sending end and trigger transient overvoltage,threatening the safe and stable operation of the power grid.However,there is a lack of research on the calculation method of transient overvoltage caused by commutation failure in high-voltage DC transmission systems with grid-forming renewable energy sources integration.Based on the existing equivalent model of highvoltage DC transmission systems at the sending end,this paper proposes to construct a model of the high-voltage DC transmission system at the sending end with grid-forming renewable energy sources.The paper first clarifies the mechanism of overvoltage generation,then considers the reactive power droop control characteristics of GF-RES,and derives the transient voltage calculation model of theDC transmission system with GF-RES integration.It also proposes a calculation method for transient overvoltage at the sending-end converter bus with GF-RES integration.Based on the PSCAD/EMTDC simulation platform,this paper builds an experimental simulation model.By constructing three different experimental scenarios,the accuracy and effectiveness of the proposed transient overvoltage calculation method are verified,with a calculation error within 5%.At the same time,this paper quantitatively analyzes the impact of grid strength,new energy proportion,and rated transmission power on transient overvoltage from three different perspectives.展开更多
Ce-based magnets have attracted extensive attention in both academia and industry due to their excellent property-price ratio and distinctive phase structures.Characteristically,Ce-based sintered magnets have widely t...Ce-based magnets have attracted extensive attention in both academia and industry due to their excellent property-price ratio and distinctive phase structures.Characteristically,Ce-based sintered magnets have widely tunable magnetic properties with changing Ce contents.Therefore,they can be used to meet many different application requirements from packaging market to driving motors,etc.The intrinsic magnetic properties,phase composition,and microstructures of the Ce-based sintered magnets with different Ce contents have been summarized.The service performances such as temperature stability,corrosion resistance,mechanical properties and thermal expansion of commercial Ce-based sintered magnets are introduced.The research and development trends of the Ce-based magnets in the future are pointed out.展开更多
[ Objective ] This study aimed to optimize the extraction process of astaxanthin from Haematococcus pluvialis with oil dissolution method. [ Method ] Small amounts of acetone or ethanol were separately added into soyb...[ Objective ] This study aimed to optimize the extraction process of astaxanthin from Haematococcus pluvialis with oil dissolution method. [ Method ] Small amounts of acetone or ethanol were separately added into soybean oil for astaxanthin extraction. The extraction efficiency of astaxanthin from H. pluvialis with different methods was compared. [ Result] The extraction efficiency of astaxanthin from H. pluvialis with acetone, acetone ＋ soybean oil, ethanol ＋ soybean oil, soybean oil was 20.46, 21.65, 20.85 mg/g and 13.05 mg/g, respectively. According to the results, acetone ＋ soybean oil led to the highest extraction rate, which was approximately twice that of soybean oil and higher than that of acetone. [ Conclusion ] This study laid the foundation for large-scale production of astaxanthin.展开更多
Objective Protein disulfide isomerase A2(PDIA2),a member of the protein disulfide isomerase family,plays a key role in the folding of nascent proteins in the endoplasmic reticulum by forming disulfide bonds,together w...Objective Protein disulfide isomerase A2(PDIA2),a member of the protein disulfide isomerase family,plays a key role in the folding of nascent proteins in the endoplasmic reticulum by forming disulfide bonds,together with enzymes such as thiol isomerase,oxidase,and reductase.This study investigated the clinical significance and potential functions of PDIA2 in glioma.Methods The expression of PDIA2 in gliomas was explored using The Cancer Genome Atlas and Gene Expression Omnibus databases.We analyzed the clinical characteristics of glioma patients and the prognostic and diagnostic value of PDIA2 expression.Kaplan-Meier and Cox regression analyses were used to examine the effect of PDIA2 expression on overall survival,progression-free interval,and disease-specific survival.Furthermore,we performed Gene Set Enrichment Analysis and immune infiltration analysis to investigate the functions of PDIA2.PDIA2 mRNA and protein expression was evaluated in cell lines and glioma tissues.Results PDIA2 was expressed at low levels in glioma patients.Kaplan-Meier survival analysis showed that glioma patients with low PDIA2 levels had a worse prognosis than those with high PDIA2 levels.Receiver operating characteristic curve analysis indicated the diagnostic and prognostic ability of PDIA2(area under the curve=0.918).Pathways associated with PD1,PI3K/AKT,cancer immunotherapy via PD1 blockade,Fceri-mediated NF-kB activation,FOXM1,and DNA repair were enriched in glioma patients with low levels of PDIA2.PDIA2 expression levels were negatively correlated with immune cell infiltrate levels.Conclusion PDIA2 levels are significantly downregulated in glioma.PDIA2 expression may be a potential biomarker for the diagnosis and prognosis of glioma patients.展开更多
s: The convenient synthesis of (-)-5αH.7β 10α-eudesmane-3. 11-dielle 1 has been achieved in four steps starting from R-(-)-carvone. The key step is the reductive deoxygenation of α,β-unsaturated tosylhydrazone to...s: The convenient synthesis of (-)-5αH.7β 10α-eudesmane-3. 11-dielle 1 has been achieved in four steps starting from R-(-)-carvone. The key step is the reductive deoxygenation of α,β-unsaturated tosylhydrazone together with the migration of the double bond.展开更多
The aim of the study was to clarify the charac-teristics of fatigue status in Chinese adolescents. 1018 adolescents (490 males, 528 females) aged 12 or 15 years in Jixi city were enrolled. Between May and September 20...The aim of the study was to clarify the charac-teristics of fatigue status in Chinese adolescents. 1018 adolescents (490 males, 528 females) aged 12 or 15 years in Jixi city were enrolled. Between May and September 2009, fatigue status was investigated using a questionnaire devised by ourselves, which consisted of 4 physical and 4 mental fatigue items. These questions were scored from 0 to 3 based on the frequency of an item occurring, given as the average of the past one month, and the fatigue scores were calculated. Lifestyle issues such as daily sleep duration, feeling of refreshment in the morning after wake-up, extracurricular sports activity, and breakfast intake, and a physical examination such as height, weight, and waist circumference were also investigated. Physical and mental fatigue scores were significantly higher in subjects aged 15 yrs old than in those aged 12 yrs old in both genders. These scores in females were significantly higher than those in males at the age of 15 yrs. Multivariate regression analysis showed that total (physical plus mental) fatigue scores were associated with female gender and various lifestyles such as unrefreshed wake-up feeling, poor extracurricular sports activity, and more frequent skipping of breakfast. However, body mass index and waist circumference were not associated with total fatigue scores.展开更多
We described a Yb(OTf)_(3) combined with Pybox ligand catalyzed asymmetric[3+3]cycloaddition of N-vinyl cinnamaldehyde nitrones with activated cyclopropanes to prepare various functionalized 1,2-oxazines in 24%—95% y...We described a Yb(OTf)_(3) combined with Pybox ligand catalyzed asymmetric[3+3]cycloaddition of N-vinyl cinnamaldehyde nitrones with activated cyclopropanes to prepare various functionalized 1,2-oxazines in 24%—95% yields and 22%—96%ee.Experimental results revealed that the reaction underwent a domino[3+3]cycloaddition,dealkenylation,and aza-1,4-addition in three steps.The chiral 1,2-oxazine could be obtained in gram scales and easily converted into various 1,2-oxazine scaffolds.The present method features broad substrate scope,good functional group compatibility,three-component domino reaction,and asymmetric[3+3]cycloaddition of N-vinyl nitrones with activated cyclopropanes.展开更多
Background Coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has spread around the world and reports of children during early epidemic period showed features of fam...Background Coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has spread around the world and reports of children during early epidemic period showed features of family clusters.The aim of this study is to assess clinical profiles of COVID-19 in family clusters with children.Methods We performed a systematic literature review of English database(PubMed,Web of Science)and Chinese database(“www.cnki.net”,“www.cqvip.com”and“www.Wanfangdata.com.cn”)to identify papers on family clusters of COVID-19 with children and their family members.Results Eighteen studies involving 34 children and 98 adults from 28 families were included.Fever,cough and ground-grass opacity change of chest computed tomography(CT)were the dominant features,whereas proportion of asymptomatic infections for children was higher than adults with statistical significance(32.4%and 13.3%,respectively,P<0.05).Median time of longer incubation period(10 days)and shorter duration of pharyngeal swab nucleic acid test positive period(11 days)were seen in children than adults(7 and 17 days,respectively)with statistical significance(P<0.05).There were statistically significant differences in lymphopenia,increased C-reactive protein and abnormal chest CT between children and adult patients(P<0.05).Twenty-seven families reported adults as first case of COVID-19 in family clusters.Conclusions The same virus strain can cause milder disease in children compared with their caregivers.Children of COVID-19 were infected by adults in family during the early epidemic period.Asymptomatic patients can transmit the virus.展开更多
基金supported by Key Natural Science Research Projects of Colleges and Universities in Anhui Province(2022AH051831).
文摘The integration of large-scale new energy and high-capacity DC transmission leads to a reduction in system inertia.Grid-forming renewable energy sources(GF-RES)has a significant improvement effect on system inertia.Commutation failure faults may cause a short-term reactive power surplus at the sending end and trigger transient overvoltage,threatening the safe and stable operation of the power grid.However,there is a lack of research on the calculation method of transient overvoltage caused by commutation failure in high-voltage DC transmission systems with grid-forming renewable energy sources integration.Based on the existing equivalent model of highvoltage DC transmission systems at the sending end,this paper proposes to construct a model of the high-voltage DC transmission system at the sending end with grid-forming renewable energy sources.The paper first clarifies the mechanism of overvoltage generation,then considers the reactive power droop control characteristics of GF-RES,and derives the transient voltage calculation model of theDC transmission system with GF-RES integration.It also proposes a calculation method for transient overvoltage at the sending-end converter bus with GF-RES integration.Based on the PSCAD/EMTDC simulation platform,this paper builds an experimental simulation model.By constructing three different experimental scenarios,the accuracy and effectiveness of the proposed transient overvoltage calculation method are verified,with a calculation error within 5%.At the same time,this paper quantitatively analyzes the impact of grid strength,new energy proportion,and rated transmission power on transient overvoltage from three different perspectives.
基金This work was financially supported by the National Natural Science Foundation of China(51590882,51331003).
文摘Ce-based magnets have attracted extensive attention in both academia and industry due to their excellent property-price ratio and distinctive phase structures.Characteristically,Ce-based sintered magnets have widely tunable magnetic properties with changing Ce contents.Therefore,they can be used to meet many different application requirements from packaging market to driving motors,etc.The intrinsic magnetic properties,phase composition,and microstructures of the Ce-based sintered magnets with different Ce contents have been summarized.The service performances such as temperature stability,corrosion resistance,mechanical properties and thermal expansion of commercial Ce-based sintered magnets are introduced.The research and development trends of the Ce-based magnets in the future are pointed out.
基金Supported by Project of Yantai Huarong Biological Technology Co.,Ltd
文摘[ Objective ] This study aimed to optimize the extraction process of astaxanthin from Haematococcus pluvialis with oil dissolution method. [ Method ] Small amounts of acetone or ethanol were separately added into soybean oil for astaxanthin extraction. The extraction efficiency of astaxanthin from H. pluvialis with different methods was compared. [ Result] The extraction efficiency of astaxanthin from H. pluvialis with acetone, acetone ＋ soybean oil, ethanol ＋ soybean oil, soybean oil was 20.46, 21.65, 20.85 mg/g and 13.05 mg/g, respectively. According to the results, acetone ＋ soybean oil led to the highest extraction rate, which was approximately twice that of soybean oil and higher than that of acetone. [ Conclusion ] This study laid the foundation for large-scale production of astaxanthin.
基金the Natural Science Foundation of Southwest Medical University(No.2016XNYD217,No.2018-ZRQN-032 and No.2016LZXNYD-G03)the National Natural Science Foundation of China(No.82072780)Sichuan Science and Technology Program(No.2022YFS0630).
文摘Objective Protein disulfide isomerase A2(PDIA2),a member of the protein disulfide isomerase family,plays a key role in the folding of nascent proteins in the endoplasmic reticulum by forming disulfide bonds,together with enzymes such as thiol isomerase,oxidase,and reductase.This study investigated the clinical significance and potential functions of PDIA2 in glioma.Methods The expression of PDIA2 in gliomas was explored using The Cancer Genome Atlas and Gene Expression Omnibus databases.We analyzed the clinical characteristics of glioma patients and the prognostic and diagnostic value of PDIA2 expression.Kaplan-Meier and Cox regression analyses were used to examine the effect of PDIA2 expression on overall survival,progression-free interval,and disease-specific survival.Furthermore,we performed Gene Set Enrichment Analysis and immune infiltration analysis to investigate the functions of PDIA2.PDIA2 mRNA and protein expression was evaluated in cell lines and glioma tissues.Results PDIA2 was expressed at low levels in glioma patients.Kaplan-Meier survival analysis showed that glioma patients with low PDIA2 levels had a worse prognosis than those with high PDIA2 levels.Receiver operating characteristic curve analysis indicated the diagnostic and prognostic ability of PDIA2(area under the curve=0.918).Pathways associated with PD1,PI3K/AKT,cancer immunotherapy via PD1 blockade,Fceri-mediated NF-kB activation,FOXM1,and DNA repair were enriched in glioma patients with low levels of PDIA2.PDIA2 expression levels were negatively correlated with immune cell infiltrate levels.Conclusion PDIA2 levels are significantly downregulated in glioma.PDIA2 expression may be a potential biomarker for the diagnosis and prognosis of glioma patients.
文摘s: The convenient synthesis of (-)-5αH.7β 10α-eudesmane-3. 11-dielle 1 has been achieved in four steps starting from R-(-)-carvone. The key step is the reductive deoxygenation of α,β-unsaturated tosylhydrazone together with the migration of the double bond.
文摘The aim of the study was to clarify the charac-teristics of fatigue status in Chinese adolescents. 1018 adolescents (490 males, 528 females) aged 12 or 15 years in Jixi city were enrolled. Between May and September 2009, fatigue status was investigated using a questionnaire devised by ourselves, which consisted of 4 physical and 4 mental fatigue items. These questions were scored from 0 to 3 based on the frequency of an item occurring, given as the average of the past one month, and the fatigue scores were calculated. Lifestyle issues such as daily sleep duration, feeling of refreshment in the morning after wake-up, extracurricular sports activity, and breakfast intake, and a physical examination such as height, weight, and waist circumference were also investigated. Physical and mental fatigue scores were significantly higher in subjects aged 15 yrs old than in those aged 12 yrs old in both genders. These scores in females were significantly higher than those in males at the age of 15 yrs. Multivariate regression analysis showed that total (physical plus mental) fatigue scores were associated with female gender and various lifestyles such as unrefreshed wake-up feeling, poor extracurricular sports activity, and more frequent skipping of breakfast. However, body mass index and waist circumference were not associated with total fatigue scores.
基金Financial support from the NSFC(22071035)Natural Science Foundation of Guangxi(2023GXNSFDA026025)+3 种基金Guangxi Science and Technology Plan Project(AD23026046)Graduate Innovation Training Program of Guangxi(YCSW2024160)Natural Science Foundation of Sichuan(2023NSFSC1087)Guangxi Bagui Young Scholar is greatly appreciated.
文摘We described a Yb(OTf)_(3) combined with Pybox ligand catalyzed asymmetric[3+3]cycloaddition of N-vinyl cinnamaldehyde nitrones with activated cyclopropanes to prepare various functionalized 1,2-oxazines in 24%—95% yields and 22%—96%ee.Experimental results revealed that the reaction underwent a domino[3+3]cycloaddition,dealkenylation,and aza-1,4-addition in three steps.The chiral 1,2-oxazine could be obtained in gram scales and easily converted into various 1,2-oxazine scaffolds.The present method features broad substrate scope,good functional group compatibility,three-component domino reaction,and asymmetric[3+3]cycloaddition of N-vinyl nitrones with activated cyclopropanes.
基金This research was funded by the National Natural Science Foundation of China(No.81771621)the Natural Science Foundation of Liaoning Province(No.2019JH8/10300023).
文摘Background Coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has spread around the world and reports of children during early epidemic period showed features of family clusters.The aim of this study is to assess clinical profiles of COVID-19 in family clusters with children.Methods We performed a systematic literature review of English database(PubMed,Web of Science)and Chinese database(“www.cnki.net”,“www.cqvip.com”and“www.Wanfangdata.com.cn”)to identify papers on family clusters of COVID-19 with children and their family members.Results Eighteen studies involving 34 children and 98 adults from 28 families were included.Fever,cough and ground-grass opacity change of chest computed tomography(CT)were the dominant features,whereas proportion of asymptomatic infections for children was higher than adults with statistical significance(32.4%and 13.3%,respectively,P<0.05).Median time of longer incubation period(10 days)and shorter duration of pharyngeal swab nucleic acid test positive period(11 days)were seen in children than adults(7 and 17 days,respectively)with statistical significance(P<0.05).There were statistically significant differences in lymphopenia,increased C-reactive protein and abnormal chest CT between children and adult patients(P<0.05).Twenty-seven families reported adults as first case of COVID-19 in family clusters.Conclusions The same virus strain can cause milder disease in children compared with their caregivers.Children of COVID-19 were infected by adults in family during the early epidemic period.Asymptomatic patients can transmit the virus.
