AIM:To quantify changes in radial peripapillary capillary vessel density(ppVD)and the peripapillary retinal nerve fiber layer(pRNFL)in children with type 1 diabetes without clinical diabetic retinopathy by optical coh...AIM:To quantify changes in radial peripapillary capillary vessel density(ppVD)and the peripapillary retinal nerve fiber layer(pRNFL)in children with type 1 diabetes without clinical diabetic retinopathy by optical coherence tomography angiography(OCTA),providing a basis for early retinopathy in children with type 1 diabetes.METHODS:This was a retrospective study.A total of 30 patients(3–14y)with type 1 diabetes without clinical diabetic retinopathy(NDR group)were included.A total of 30 age-matched healthy subjects were included as the normal control group(CON group).The HbA1c level in the last 3mo was measured once in the NDR group.The pRNFL thickness and ppVD were automatically measured,and the mean pRNFL and ppVD were calculated in the nasal,inferior,temporal,and superior quadrants.The changes in ppVD and pRNFL in the two groups were analyzed.RESULTS:Compared with CON group,the nasal and superior ppVDs decreased in the NDR group(all P<0.01).The thickness of the nasal pRNFL decreased significantly(P<0.01),while the inferior,temporal and superior pRNFLs slightly decreased but not significant in the NDR group(all P>0.05).Person and Spearman correlation analysis of ppVD and pRNFL thickness in each quadrant of the NDR group showed a positive correlation between nasal and superior(all P<0.01),while inferior and temporal had no significant correlation(all P>0.05).There was no significant correlation between the HbA1c level and ppVD and pRNFL in any quadrant(all P>0.05).There was no significant correlation between the course of diabetes mellitus and ppVD and pRNFL in any quadrant(all P>0.05).CONCLUSION:ppVD and pRNFL decrease in eyes of children with type 1 diabetes before clinically detectable retinopathy and OCTA is helpful for early monitoring.展开更多
BACKGROUND Commonly used glucocorticoids replacement regimens in patients with hypopituitarism have difficulty mimicking physiological cortisol rhythms and are usually accompanied by risks of over-treatment,with adver...BACKGROUND Commonly used glucocorticoids replacement regimens in patients with hypopituitarism have difficulty mimicking physiological cortisol rhythms and are usually accompanied by risks of over-treatment,with adverse effects on glucose metabolism.Disorders associated with glucose metabolism are established risk factors of cardiovascular events,one of the life-threatening ramifications.AIM To investigate the glycometabolism profile in patients with hypopituitarism receiving prednisone(Pred)replacement,and to clarify the impacts of different Pred doses on glycometabolism and consequent adverse cardiovascular outcomes.METHODS Twenty patients with hypopituitarism receiving Pred replacement[patient group(PG)]and 20 normal controls(NCs)were recruited.A flash glucose monitoring system was used to record continuous glucose levels during the day,which provided information on glucose-target-rate,glucose variability(GV),period glucose level,and hypoglycemia occurrence at certain periods.Islet β-cell function was also assessed.Based on the administered Pred dose per day,the PG was then regrouped into Pred>5 mg/d and Pred≤5 mg/d subgroups.Comparative analysis was carried out between the PG and NCs.RESULTS Significantly altered glucose metabolism profiles were identified in the PG.This includes significant reductions in glucose-target-rate and nocturnal glucose level,along with elevations in GV,hypoglycemia occurrence and postprandial glucose level,when compared with those in NCs.Subgroup analysis indicated more significant glucose metabolism impairment in the Pred>5 mg/d group,including significantly decreased glucose-target-rate and nocturnal glucose level,along with increased GV,hypoglycemia occurrence,and postprandial glucose level.With regard to islet β-cell function,PG showed significant difference in homeostasis model assessment(HOMA)-β compared with that of NCs;a notable difference in HOMA-βwas identified in Pred>5 mg/d group when compared with those of NCs;as for Pred≤5 mg/d group,significant differences were found in HOMA-β,and fasting glucose/insulin ratio when compared with NCs.CONCLUSION Our results demonstrated that Pred replacement disrupted glycometabolic homeostasis in patients with hypopituitarism.A Pred dose of>5 mg/d seemed to cause more adverse effects on glycometabolism than a dose of≤5 mg/d.Comprehensive and accurate evaluation is necessary to consider a suitable Pred replacement regimen,wherein,flash glucose monitoring system is a kind of promising and reliable assessment device.The present data allows us to thoroughly examine our modern treatment standards,especially in difficult cases such as hormonal replacement mimicking delicate natural cycles,in conditions such as diabetes mellitus that are rapidly growing in worldwide prevalence.展开更多
AIM: To investigate the expression of selenoprotein P mRNA (SePmRNA) in tissues of normal liver, liver cirrhosis and hepatocellular carcinoma (HCC), and its relationship with HCC occurrence and development. METHODS: T...AIM: To investigate the expression of selenoprotein P mRNA (SePmRNA) in tissues of normal liver, liver cirrhosis and hepatocellular carcinoma (HCC), and its relationship with HCC occurrence and development. METHODS: The expression of SePmRNA in tissues of normal liver, liver cirrhosis and HCC were detected by in situ hybridization using a cDNA probe. RESULTS: The enzyme digesting products of PBluescript-H uman Selenoprotein P were evaluated by electrophoresis. The positive expression of SePmRNA was found in the tissues of normal liver, liver cirrhosis and HCC. The expression of SeP mRNA was found in hepatic interstitial substance, especially in endothelial cells and lymphocytes of vasculature. The positive rate of SePmRNA in normal liver tissue was 84.6% (11/13) and the positive signals appeared in the nucleus and cytoplasm, mostly in the nucleolus, and the staining granules were larger in the nucleolus and around the nucleus. The positive rate of SePmRNA in liver cirrhosis tissue was 45.0% (9/20) and the positive signals were mainly in the nucleolus and cytoplasm, being less around the nucleus and inner nucleus than that in normal liver tissue. The positive rate of SePmRNA in HCC tissue was 30.0% (9/30) and the positive signals were in the cytoplasm, but less in the nucleus. CONCLUSION: SePmRNA expression in the tissues of normal liver and HCC is significantly different (84.6% vs 30.0%, P = 0.003), suggesting that SeP might play a role in the occurrence and development of HCC.展开更多
Objective:To explore the value of increased fetal cardio thoracic ratio(CTR)in predicting adverse fetal pregnancy outcome during 11-13+6 weeks.Methods:The ultrasonographic features,chromosome or gene detection and the...Objective:To explore the value of increased fetal cardio thoracic ratio(CTR)in predicting adverse fetal pregnancy outcome during 11-13+6 weeks.Methods:The ultrasonographic features,chromosome or gene detection and the pregnancy outcome of 86 fetuses with increased CTR at 11-13+6 weeks’gestation were retrospectively analyzed.Fetuses were divided into non-structural malformation group(46 cases)and structural malformation group(40 cases)according to results of fetal ultrasound examination.The differences of CTR and nuchal translucency thickness(NT)between the two groups were compared by t test.The area under the curve(AUC)was calculated by constructing the receiver operating curve(ROC)to determine the best diagnostic threshold,sensitivity and specificity of CTR and NT in predicting chromosomal abnormalities.Results:All the 86 fetuses had serious problems such as chromosome or gene abnormalities,or structural malformations.The CTR and NT of the structural malformation group were significantly higher than those of the non-structural malformation group,and the difference was statistically significant(P<0.05).Through villous biopsy of 60 fetuses,47 cases(78.3%,47/60)with haemoglobin Bart’s disease,10 cases(16.7%,10/60)with chromosomal abnormalities were detected,and none abnormalities were detected in other 3 cases.According to the ROC curve,the AUC for CTR and NT to predict chromosomal abnormalities are 0.691 and 0.954,respectively,and the diagnostic cut-off values are 0.57 and 3.6 mm,respectively.The sensitivity is 60.0%and 100%,the specificity is about 79.6%and 85.7%,respectively.Follow-up showed that 5 cases of fetal were death intrauterine,and the remaining 81 cases were induced to labor.The specificity of CTR increase in predicting adverse pregnancy outcome was 100%.Conclusion:The increase of CTR in 11-13+6 weeks of gestation indicates that the fetus may have serious problems and poor clinical prognosis.Attention should be paid to the accurate evaluation of CTR in early pregnancy so as to provide reference for the prediction of fetal pregnancy outcome.展开更多
Background: Danshen is an important traditional Chinese medicine(TCM) used for the treatment of cardiovascular and cerebrovascular diseases. Separation and analysis of its components have been widely investigated. How...Background: Danshen is an important traditional Chinese medicine(TCM) used for the treatment of cardiovascular and cerebrovascular diseases. Separation and analysis of its components have been widely investigated. However, the systematical two dimensional liquid chromatography(2D-LC) methods have not been developed to comprehensively separate and characterize its components.Objective: In this work, double off-line 2D-LC methods were aimed to develop for the systematical separation of compounds from Danshen.Methods: Using solid phase extraction(SPE), the Danshen extract was divided into a medium-polar fraction(Sample I) and a weak-polar fraction(Sample Ⅱ) according to their polarities. Based on reversed-phase liquid chromatography(RPLC) and hydrophilic interaction liquid chromatography(HILIC) modes, a 2D-HILIC × RPLC system and a 2D-RPLC × RPLC system were designed for the separation of Sample Ⅰ and Sample Ⅱ, respectively. According to reversed-phase and HILIC columns selectivities characterized in our previous reports, ZIC-HILIC and XTerra C18 were employed to build the 2D-HILIC × RPLC system and Click TE-CD and XTerra C18 for the 2D-RPLC × RPLC system,respectively.Results: The 2D-HILIC × RPLC and 2D-RPLC × RPLC systems exhibited excellent orthogonality for the separation of Sample Ⅰ and Sample Ⅱ,respectively. Their orthogonalities were 88.42% and 63.24%. Based on these double 2D-LC systems combined with mass spectrometry, at least 200 compounds were found and 33 compounds of them were identified, including 16 phenolic acids and 17 diterpenoid quinines.Conclusion: These results suggest that these two off-line 2D-LC methods are effective for the separation and characterization of components in Danshen.展开更多
Quinoxaline-3-carboxylates and analogues are prevalent key structural motifs in bioactive natural products and synthetic drugs.However, the practical protocol for preparation of these motifs from simple raw materials ...Quinoxaline-3-carboxylates and analogues are prevalent key structural motifs in bioactive natural products and synthetic drugs.However, the practical protocol for preparation of these motifs from simple raw materials under mild conditions remains rare. In this article, we report a facile protocol for the efficient preparation of various quinoxaline-3-carbonyl compounds(30 examples,63%–92%) through oxidation coupling of quinoxalin-2(1H)-ones with readily available carbazates(or acyl hydrazines) in the presence of K_2S_2O_8 as an oxidant in metal-and base-free conditions. When tert-butyl carbazate was used as the coupling reagent,the decarboxylation product 3-(tert-butyl)-1-methylquinoxalin-2(1H)-one was obtained. The application of this process into a gram-scale synthesis can be easily accomplished. Mechanistic investigations reveal that the functionalization of quinoxalin-2(1H)-ones via a free-radical pathway.展开更多
In situ selective carbothermic reactions and vacuum sintering were used to prepare iron-based friction material directly vanadium-bearing titanomagnetite concentrates.Effects of phosphorus addition(0.05–0.20 wt.%)on ...In situ selective carbothermic reactions and vacuum sintering were used to prepare iron-based friction material directly vanadium-bearing titanomagnetite concentrates.Effects of phosphorus addition(0.05–0.20 wt.%)on the microstructure and properties of iron-based friction material were investigated.The results show that the addition of phosphorus improves the microstructure and properties of the material significantly.When phosphorus addition increases to 0.15 wt.%,the sintering densification is promoted and the number of lamellar pearlites increases.Therefore,the relative density,hardness and tribological properties of the material are greatly enhanced.Particularly,the friction coefficient decreases 0.58 to 0.43,and the wear rate reduces 1.829×10^(–7) to 0.694×10^(–7)cm^(3)J^(-1).The dominant wear mechanism of the material changes severe abrasive wear to mild oxidation wear accordingly.However,when phosphorus addition exceeds 0.15 wt.%,the matrix continuity and tribological properties of the material are deteriorated.Comprehensively,the optimal addition of phosphorus in the iron-based friction material is 0.15 wt.%.展开更多
Objective:In this study,a comprehensive and effective quality method for evaluating the efficacy of ShuXueNing injection(SXNI)was developed.Materials and Methods:Quantitative high-performance liquid chromatography fin...Objective:In this study,a comprehensive and effective quality method for evaluating the efficacy of ShuXueNing injection(SXNI)was developed.Materials and Methods:Quantitative high-performance liquid chromatography fingerprint,the quantitative analysis of multicomponents by a single marker(QAMS)method,hierarchical cluster analysis(HCA),and orthogonal partial least squares discrimination analysis(OPLS-DA)were used to distinguish 53 batches of SXNI samples from 7 manufacturers.Results:A total of 53 batches of samples were analyzed to establish antithesis fingerprint of SXNI,and 12 peaks of the common model were collected and used for the similarity analysis.Meanwhile,six index flavonoid components were determined by the QAMS method,using rutin as internal reference substance.The accuracy of the QAMS method was confirmed by investigating the relative deviation between the QAMS method and the traditional external standard method.The results demonstrated that there was no significant difference(RE<1%),suggesting that QAMS was a reliable and convenient method for the content determination of multiple components.The HCA and OPLS-DA methods drew a similar conclusion.The 53 batches of SXNI samples from 7 manufacturers were categorized into five groups,indicating that chemometrics could reveal the quality differences of SXNI between the manufacturers.Conclusions:The method established herein was efficient and successful in assessing the quality of SXNI,and that it may be potentially employed in the quality control of related products composed of Ginkgo biloba extract.展开更多
基金Supported by Xi’an Municipal Health Commission Scientific Research Project(No.2023yb22)Hospital Level Project of Xi’an Children’s Hospital(No.2021H12No.2022F08).
文摘AIM:To quantify changes in radial peripapillary capillary vessel density(ppVD)and the peripapillary retinal nerve fiber layer(pRNFL)in children with type 1 diabetes without clinical diabetic retinopathy by optical coherence tomography angiography(OCTA),providing a basis for early retinopathy in children with type 1 diabetes.METHODS:This was a retrospective study.A total of 30 patients(3–14y)with type 1 diabetes without clinical diabetic retinopathy(NDR group)were included.A total of 30 age-matched healthy subjects were included as the normal control group(CON group).The HbA1c level in the last 3mo was measured once in the NDR group.The pRNFL thickness and ppVD were automatically measured,and the mean pRNFL and ppVD were calculated in the nasal,inferior,temporal,and superior quadrants.The changes in ppVD and pRNFL in the two groups were analyzed.RESULTS:Compared with CON group,the nasal and superior ppVDs decreased in the NDR group(all P<0.01).The thickness of the nasal pRNFL decreased significantly(P<0.01),while the inferior,temporal and superior pRNFLs slightly decreased but not significant in the NDR group(all P>0.05).Person and Spearman correlation analysis of ppVD and pRNFL thickness in each quadrant of the NDR group showed a positive correlation between nasal and superior(all P<0.01),while inferior and temporal had no significant correlation(all P>0.05).There was no significant correlation between the HbA1c level and ppVD and pRNFL in any quadrant(all P>0.05).There was no significant correlation between the course of diabetes mellitus and ppVD and pRNFL in any quadrant(all P>0.05).CONCLUSION:ppVD and pRNFL decrease in eyes of children with type 1 diabetes before clinically detectable retinopathy and OCTA is helpful for early monitoring.
基金Supported by National Natural Science Foundation of China,No.81770776,No.81973378,and No.82073909The Shanxi Provincial Central Leading Local Science and Technology Development Fund Project,No.YDZJSX2022A059Postgraduate Education Innovation Project of Shanxi Province,No.2022Y354.
文摘BACKGROUND Commonly used glucocorticoids replacement regimens in patients with hypopituitarism have difficulty mimicking physiological cortisol rhythms and are usually accompanied by risks of over-treatment,with adverse effects on glucose metabolism.Disorders associated with glucose metabolism are established risk factors of cardiovascular events,one of the life-threatening ramifications.AIM To investigate the glycometabolism profile in patients with hypopituitarism receiving prednisone(Pred)replacement,and to clarify the impacts of different Pred doses on glycometabolism and consequent adverse cardiovascular outcomes.METHODS Twenty patients with hypopituitarism receiving Pred replacement[patient group(PG)]and 20 normal controls(NCs)were recruited.A flash glucose monitoring system was used to record continuous glucose levels during the day,which provided information on glucose-target-rate,glucose variability(GV),period glucose level,and hypoglycemia occurrence at certain periods.Islet β-cell function was also assessed.Based on the administered Pred dose per day,the PG was then regrouped into Pred>5 mg/d and Pred≤5 mg/d subgroups.Comparative analysis was carried out between the PG and NCs.RESULTS Significantly altered glucose metabolism profiles were identified in the PG.This includes significant reductions in glucose-target-rate and nocturnal glucose level,along with elevations in GV,hypoglycemia occurrence and postprandial glucose level,when compared with those in NCs.Subgroup analysis indicated more significant glucose metabolism impairment in the Pred>5 mg/d group,including significantly decreased glucose-target-rate and nocturnal glucose level,along with increased GV,hypoglycemia occurrence,and postprandial glucose level.With regard to islet β-cell function,PG showed significant difference in homeostasis model assessment(HOMA)-β compared with that of NCs;a notable difference in HOMA-βwas identified in Pred>5 mg/d group when compared with those of NCs;as for Pred≤5 mg/d group,significant differences were found in HOMA-β,and fasting glucose/insulin ratio when compared with NCs.CONCLUSION Our results demonstrated that Pred replacement disrupted glycometabolic homeostasis in patients with hypopituitarism.A Pred dose of>5 mg/d seemed to cause more adverse effects on glycometabolism than a dose of≤5 mg/d.Comprehensive and accurate evaluation is necessary to consider a suitable Pred replacement regimen,wherein,flash glucose monitoring system is a kind of promising and reliable assessment device.The present data allows us to thoroughly examine our modern treatment standards,especially in difficult cases such as hormonal replacement mimicking delicate natural cycles,in conditions such as diabetes mellitus that are rapidly growing in worldwide prevalence.
基金Project(51501092)supported by the National Natural Science Foundation of ChinaProject(30915011332)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2014M550292)supported by China Postdoctoral Science Foundation
基金Supported by Science and Technology Investigation and Development Project of Shaanxi Province, No. 2002K10-G1
文摘AIM: To investigate the expression of selenoprotein P mRNA (SePmRNA) in tissues of normal liver, liver cirrhosis and hepatocellular carcinoma (HCC), and its relationship with HCC occurrence and development. METHODS: The expression of SePmRNA in tissues of normal liver, liver cirrhosis and HCC were detected by in situ hybridization using a cDNA probe. RESULTS: The enzyme digesting products of PBluescript-H uman Selenoprotein P were evaluated by electrophoresis. The positive expression of SePmRNA was found in the tissues of normal liver, liver cirrhosis and HCC. The expression of SeP mRNA was found in hepatic interstitial substance, especially in endothelial cells and lymphocytes of vasculature. The positive rate of SePmRNA in normal liver tissue was 84.6% (11/13) and the positive signals appeared in the nucleus and cytoplasm, mostly in the nucleolus, and the staining granules were larger in the nucleolus and around the nucleus. The positive rate of SePmRNA in liver cirrhosis tissue was 45.0% (9/20) and the positive signals were mainly in the nucleolus and cytoplasm, being less around the nucleus and inner nucleus than that in normal liver tissue. The positive rate of SePmRNA in HCC tissue was 30.0% (9/30) and the positive signals were in the cytoplasm, but less in the nucleus. CONCLUSION: SePmRNA expression in the tissues of normal liver and HCC is significantly different (84.6% vs 30.0%, P = 0.003), suggesting that SeP might play a role in the occurrence and development of HCC.
基金Guangdong Provincial Medical Research Fund(No.A2018159)。
文摘Objective:To explore the value of increased fetal cardio thoracic ratio(CTR)in predicting adverse fetal pregnancy outcome during 11-13+6 weeks.Methods:The ultrasonographic features,chromosome or gene detection and the pregnancy outcome of 86 fetuses with increased CTR at 11-13+6 weeks’gestation were retrospectively analyzed.Fetuses were divided into non-structural malformation group(46 cases)and structural malformation group(40 cases)according to results of fetal ultrasound examination.The differences of CTR and nuchal translucency thickness(NT)between the two groups were compared by t test.The area under the curve(AUC)was calculated by constructing the receiver operating curve(ROC)to determine the best diagnostic threshold,sensitivity and specificity of CTR and NT in predicting chromosomal abnormalities.Results:All the 86 fetuses had serious problems such as chromosome or gene abnormalities,or structural malformations.The CTR and NT of the structural malformation group were significantly higher than those of the non-structural malformation group,and the difference was statistically significant(P<0.05).Through villous biopsy of 60 fetuses,47 cases(78.3%,47/60)with haemoglobin Bart’s disease,10 cases(16.7%,10/60)with chromosomal abnormalities were detected,and none abnormalities were detected in other 3 cases.According to the ROC curve,the AUC for CTR and NT to predict chromosomal abnormalities are 0.691 and 0.954,respectively,and the diagnostic cut-off values are 0.57 and 3.6 mm,respectively.The sensitivity is 60.0%and 100%,the specificity is about 79.6%and 85.7%,respectively.Follow-up showed that 5 cases of fetal were death intrauterine,and the remaining 81 cases were induced to labor.The specificity of CTR increase in predicting adverse pregnancy outcome was 100%.Conclusion:The increase of CTR in 11-13+6 weeks of gestation indicates that the fetus may have serious problems and poor clinical prognosis.Attention should be paid to the accurate evaluation of CTR in early pregnancy so as to provide reference for the prediction of fetal pregnancy outcome.
基金funded by Project of National Science Foundation of China(81473436,81274077 and 81403100)
文摘Background: Danshen is an important traditional Chinese medicine(TCM) used for the treatment of cardiovascular and cerebrovascular diseases. Separation and analysis of its components have been widely investigated. However, the systematical two dimensional liquid chromatography(2D-LC) methods have not been developed to comprehensively separate and characterize its components.Objective: In this work, double off-line 2D-LC methods were aimed to develop for the systematical separation of compounds from Danshen.Methods: Using solid phase extraction(SPE), the Danshen extract was divided into a medium-polar fraction(Sample I) and a weak-polar fraction(Sample Ⅱ) according to their polarities. Based on reversed-phase liquid chromatography(RPLC) and hydrophilic interaction liquid chromatography(HILIC) modes, a 2D-HILIC × RPLC system and a 2D-RPLC × RPLC system were designed for the separation of Sample Ⅰ and Sample Ⅱ, respectively. According to reversed-phase and HILIC columns selectivities characterized in our previous reports, ZIC-HILIC and XTerra C18 were employed to build the 2D-HILIC × RPLC system and Click TE-CD and XTerra C18 for the 2D-RPLC × RPLC system,respectively.Results: The 2D-HILIC × RPLC and 2D-RPLC × RPLC systems exhibited excellent orthogonality for the separation of Sample Ⅰ and Sample Ⅱ,respectively. Their orthogonalities were 88.42% and 63.24%. Based on these double 2D-LC systems combined with mass spectrometry, at least 200 compounds were found and 33 compounds of them were identified, including 16 phenolic acids and 17 diterpenoid quinines.Conclusion: These results suggest that these two off-line 2D-LC methods are effective for the separation and characterization of components in Danshen.
基金supported by the Hunan Provincial Natural Science Foundation of China (2019JJ20008)the Construct Program of Applied Characteristic Discipline in Hunan University of Science and Engineering
文摘Quinoxaline-3-carboxylates and analogues are prevalent key structural motifs in bioactive natural products and synthetic drugs.However, the practical protocol for preparation of these motifs from simple raw materials under mild conditions remains rare. In this article, we report a facile protocol for the efficient preparation of various quinoxaline-3-carbonyl compounds(30 examples,63%–92%) through oxidation coupling of quinoxalin-2(1H)-ones with readily available carbazates(or acyl hydrazines) in the presence of K_2S_2O_8 as an oxidant in metal-and base-free conditions. When tert-butyl carbazate was used as the coupling reagent,the decarboxylation product 3-(tert-butyl)-1-methylquinoxalin-2(1H)-one was obtained. The application of this process into a gram-scale synthesis can be easily accomplished. Mechanistic investigations reveal that the functionalization of quinoxalin-2(1H)-ones via a free-radical pathway.
基金financially supported by the Science and Technology Plan of Panzhihua City in Sichuan Province of China under Grant No.2017CY-C-1.
文摘In situ selective carbothermic reactions and vacuum sintering were used to prepare iron-based friction material directly vanadium-bearing titanomagnetite concentrates.Effects of phosphorus addition(0.05–0.20 wt.%)on the microstructure and properties of iron-based friction material were investigated.The results show that the addition of phosphorus improves the microstructure and properties of the material significantly.When phosphorus addition increases to 0.15 wt.%,the sintering densification is promoted and the number of lamellar pearlites increases.Therefore,the relative density,hardness and tribological properties of the material are greatly enhanced.Particularly,the friction coefficient decreases 0.58 to 0.43,and the wear rate reduces 1.829×10^(–7) to 0.694×10^(–7)cm^(3)J^(-1).The dominant wear mechanism of the material changes severe abrasive wear to mild oxidation wear accordingly.However,when phosphorus addition exceeds 0.15 wt.%,the matrix continuity and tribological properties of the material are deteriorated.Comprehensively,the optimal addition of phosphorus in the iron-based friction material is 0.15 wt.%.
基金supported financially by the Guangxi Science and Technology Research Project(GuiKeAA18242040)the National Science and Technology Major Project(2018ZX09735-002)。
文摘Objective:In this study,a comprehensive and effective quality method for evaluating the efficacy of ShuXueNing injection(SXNI)was developed.Materials and Methods:Quantitative high-performance liquid chromatography fingerprint,the quantitative analysis of multicomponents by a single marker(QAMS)method,hierarchical cluster analysis(HCA),and orthogonal partial least squares discrimination analysis(OPLS-DA)were used to distinguish 53 batches of SXNI samples from 7 manufacturers.Results:A total of 53 batches of samples were analyzed to establish antithesis fingerprint of SXNI,and 12 peaks of the common model were collected and used for the similarity analysis.Meanwhile,six index flavonoid components were determined by the QAMS method,using rutin as internal reference substance.The accuracy of the QAMS method was confirmed by investigating the relative deviation between the QAMS method and the traditional external standard method.The results demonstrated that there was no significant difference(RE<1%),suggesting that QAMS was a reliable and convenient method for the content determination of multiple components.The HCA and OPLS-DA methods drew a similar conclusion.The 53 batches of SXNI samples from 7 manufacturers were categorized into five groups,indicating that chemometrics could reveal the quality differences of SXNI between the manufacturers.Conclusions:The method established herein was efficient and successful in assessing the quality of SXNI,and that it may be potentially employed in the quality control of related products composed of Ginkgo biloba extract.
