Viral infectious diseases,characterized by their intricate nature and wide-ranging diversity,pose substantial challenges in the domain of data management.The vast volume of data generated by these diseases,spanning fr...Viral infectious diseases,characterized by their intricate nature and wide-ranging diversity,pose substantial challenges in the domain of data management.The vast volume of data generated by these diseases,spanning from the molecular mechanisms within cells to large-scale epidemiological patterns,has surpassed the capabilities of traditional analytical methods.In the era of artificial intelligence(AI)and big data,there is an urgent necessity for the optimization of these analytical methods to more effectively handle and utilize the information.Despite the rapid accumulation of data associated with viral infections,the lack of a comprehensive framework for integrating,selecting,and analyzing these datasets has left numerous researchers uncertain about which data to select,how to access it,and how to utilize it most effectively in their research.This review endeavors to fill these gaps by exploring the multifaceted nature of viral infectious diseases and summarizing relevant data across multiple levels,from the molecular details of pathogens to broad epidemiological trends.The scope extends from the micro-scale to the macro-scale,encompassing pathogens,hosts,and vectors.In addition to data summarization,this review thoroughly investigates various dataset sources.It also traces the historical evolution of data collection in the field of viral infectious diseases,highlighting the progress achieved over time.Simultaneously,it evaluates the current limitations that impede data utilization.Furthermore,we propose strategies to surmount these challenges,focusing on the development and application of advanced computational techniques,AI-driven models,and enhanced data integration practices.By providing a comprehensive synthesis of existing knowledge,this review is designed to guide future research and contribute to more informed approaches in the surveillance,prevention,and control of viral infectious diseases,particularly within the context of the expanding big-data landscape.展开更多
Parkinson’s disease patients,in addition to typical motor symptoms,often experience various psychological symptoms,including depression,anxiety,cognitive impairment,impulse control disorders,and psychotic symptoms.Th...Parkinson’s disease patients,in addition to typical motor symptoms,often experience various psychological symptoms,including depression,anxiety,cognitive impairment,impulse control disorders,and psychotic symptoms.These symptoms severely affect patients’quality of life and may even cause a greater disease burden than motor symptoms.This review focuses on the application progress of transcranial magnetic stimulation(TMS)as a non-invasive neuromodulation technique in the treatment of psychological symptoms in Parkinson’s disease.Studies have shown that repetitive TMS(rTMS)has significant improvement effects on Parkinson’s disease-related depressive symptoms,with mechanisms possibly related to the regulation of the prefrontal-striatal dopamine pathway and the promotion of neuroplasticity.For anxiety symptoms,continuous theta burst stimulation has shown potential in indirect regulation of the amygdala and hippocampal regions.For cognitive impairment,high-frequency rTMS applied to the dorsolateral prefrontal cortex can improve executive function deficits,while bilateral coordinated stimulation protocols help enhance attention and memory functions.For impulse control disorders in Parkinson’s disease patients,inhibitory stimulation applied to the orbitofrontal cortex can alleviate pathological gambling and compulsive behaviors.In terms of sleep disorders,TMS has also shown potential efficacy in regulating circadian rhythms and improving rapid eye movement sleep behavior disorder.However,current research still has limitations such as small sample sizes,non-standardized stimulation protocols,and insufficient evaluation of long-term efficacy.Future research directions should focus on optimizing stimulation parameters,exploring individualized treatment protocols,integrating multimodal imaging assessments,and conducting large-sample randomized controlled trials to clarify the clinical application value of TMS in the rehabilitation of psychological symptoms in Parkinson’s disease,providing new approaches for the comprehensive management of this common neurodegenerative disease.展开更多
In order to estimate the residual stresses in Ti2AlNb alloy jointed by electron beam welding (EBW), a computational approach based on finite element method was developed. Meanwhile, experiments were carried out to ver...In order to estimate the residual stresses in Ti2AlNb alloy jointed by electron beam welding (EBW), a computational approach based on finite element method was developed. Meanwhile, experiments were carried out to verify the numerical results. The comparison between the simulation results and measurements suggests that the developed computational approach has sufficient accuracy to predict the welding residual stress distributions. The results show that the central area of the fusion zone suffers tensile stresses in three directions. When the other parameters remain unchanged, the focus current has great impact on the weld shape and size, and then affects the residual stress level significantly. Moreover, the thick plate full-penetrated EBW weld suffers near 1000 MPa tensile stress of Z-direction in the center of the fusion zone. The wider weld has lower tensile stress in Z-direction, resulting in lower risk for cracking.展开更多
Numerical simulation and experimental methods were used to investigate the effects of weld penetration on tensile properties of 2219 aluminum alloy tungsten inert gas(TIG)welded joints.The results show that when other...Numerical simulation and experimental methods were used to investigate the effects of weld penetration on tensile properties of 2219 aluminum alloy tungsten inert gas(TIG)welded joints.The results show that when other geometric parameters are consistent,within a certain range,the deeper the weld penetration of the capping weld is,the lower the tensile strength of the j oint is.The deeper weld penetration of the capping weld can cause the more concentrated stress at the weld toe and the joint is more likely to crack accordingly.Based on necessary assumptions,a model for analyzing the mathematical relation between the weld penetration of the capping weld and the tensile strength of the joint was proposed to validate the experimental results. The decrease of weld penetration of capping weld can be controlled by decreasing welding current,helium content or increasing welding voltage.展开更多
In order to clarify the characteristics and formation mechanism of the reheat cracking in Ti2AlNb weldments,a series of heat treatment conditions were performed to the circular joints welded by electron beam,and then ...In order to clarify the characteristics and formation mechanism of the reheat cracking in Ti2AlNb weldments,a series of heat treatment conditions were performed to the circular joints welded by electron beam,and then the macrostructures and microstructures were investigated using optical microscopy,scanning electron microscopy,X-ray diffractometry,and transmission electron microscopy.The results show that the reheat cracking occurs primarily along the grain boundaries in the weld when the Ti2AlNb circular welded joints are heated up to about 700℃.During the heat treatment,an almost complete transformation of B2→O happens while the temperature goes up through the O single-phase region.Then,O→B2+O phase transformation occurs primarily along the grain boundaries as the weld metal continues to heat up to the B2+O dual-phase region.Under the high tension stress consisting of welding residual stress and phase transformation stress,reheat cracking occurs at the interface between the B2+O dual-phase layer and the O-phase matrix.展开更多
Wall structures were made by cold metal transfer-based wire and arc additive manufacturing using two kinds of ER2319 welding wires with and without Cd elements. T6 heat treatment was used to improve mechanical propert...Wall structures were made by cold metal transfer-based wire and arc additive manufacturing using two kinds of ER2319 welding wires with and without Cd elements. T6 heat treatment was used to improve mechanical properties of these wall structures. Due to the higher vacancy binding energy of Cd, Cd-vacancy clusters are formed in the aging process and provide a large number of nucleation locations for θ′ phases. The higher diffusion coefficient of the Cd-vacancy cluster and the lower interfacial energy of θ′ phase lead to the formation of dense θ′ phases in the heat-treated α(Al). According to the strengthening model, after adding Cd in ER2319 welding wires, the yield strength increases by 43 MPa in the building direction of the heat-treated wall structures.展开更多
In as-welded state,each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases.After the...In as-welded state,each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases.After the post-weld heat treatment,both the amount and the size of the eutectic structure orθphases decreased.Correspondingly,both the Cu content inα-Al matrix and the microhardness increased to a similar level in each region of the joint,and the tensile strength of the entire joint was greatly improved.Post-weld heat treatment played the role of solid solution strengthening and aging strengthening.After the post-weld heat treatment,the weld performance became similar to other regions,but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect.The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties,and the specimens randomly crack in the weld zone.展开更多
AIM： To investigate the clinicopathological features of gastrointestinal stromal tumor （GIST） and to study the reference indexes for malignancy. METHODS： Fifty-two cases of primary GIST were distinguished from a g...AIM： To investigate the clinicopathological features of gastrointestinal stromal tumor （GIST） and to study the reference indexes for malignancy. METHODS： Fifty-two cases of primary GIST were distinguished from a group of gastrointestinal mesenchymal tumors using a panel of antibodies such as CD117 and CD34 by immunohistochemical SP method. Their biological behaviors were analyzed using the expression of p21WAF1 and Bax in 52 cases of GIST. RESULTS： Grossly, the tumor size was between 1.5 cm and 13 cm （mean： 5.5 cm）. Focal areas of hemorrhage, necrosis, or small cyst formation could be seen. Microscopically, the tumor was composed of spindle cells （20 cases）, epithelioid cells （20 cases） and mixed cells （12 cases）. Immunohistochemically, CDl17 and CD34 showed diffuse strong positive expressions, the positive rates were 98.1% and 92.3%. SMA, S-100, NSE, NF and MBP showed focal positive expressions, the positive rates were 48.1%, 28.8%, 25%, 21.2% and 42.3% respectively. Vimentins were all positive desmin and CgA were all negative. In normal adult stomach and intestine, the immunoreactive staining for CD117 and CD34 showed immunoreactive interstitial cells of Cajal in myenteric neuroplexus. Among the 52 cases of GIST, 27 were positive for p21WAF1 （51.9%）, 29 for Bax （55.8%）. The expression of p21WAF1 and Bax had no significent difference with the localization, size, histological subtype of GIST, but had a significent difference with the histological grade （P = 0.000, respectively）, p21WAF1 expression had a positive correlation to Bax expression （r = 0.461, P = 0.001, k = 0.459）. CONCLUSION： GIST has complicated arrangements and various cell types. Positivity of CD117 and CD34 is the most valuable factor in diagnosing GIST. Expression of p21WAF1 and Bax plays an important role in potential malignancy and malignancy rather than in benign GIST. p21WAF1 and Bax may be used as the markers in the assessment of GIST malignant potential.展开更多
Transient liquid phase(TLP)bonding is a potential high-temperature(HT)electron packaging technology that is used inthe interconnection of wide band-gap semiconductors.This study focused on the mechanism of intermetall...Transient liquid phase(TLP)bonding is a potential high-temperature(HT)electron packaging technology that is used inthe interconnection of wide band-gap semiconductors.This study focused on the mechanism of intermetallic compounds(IMCs)evolution in Ag/Sn TLP soldering at different temperatures.Experimental results indicated that morphologies of Ag3Sn grains mainlywere scallop-type,and some other shapes such as prism,needle,hollow column,sheet and wire of Ag3Sn grains were also observed,which was resulted from their anisotropic growths.However,the scallop-type Ag3Sn layer turned into more planar with prolongingsoldering time,due to grain coarsening and anisotropic mass flow of Ag atoms from substrate.Furthermore,a great amount ofnano-Ag3Sn particles were found on the surfaces of Ag3Sn grains,which were formed in Ag-rich areas of the molten Sn and adsorbedby the Ag3Sn grains during solidification process.Growth kinetics of the Ag3Sn IMCs in TLP soldering followed a parabolicrelationship with soldering time,and the growth rate constants of250,280and320°C were calculated as5.83×10-15m2/s,7.83×10-15m2/s and2.83×10-14m2/s,respectively.Accordingly,the activation energy of the reaction was estimated about58.89kJ/mol.展开更多
Objective: To evaluate the effect of salidroside on oxygen and glucose deprivation(OGD)-treated NT2 cells and its underlying mechanisms of action.Methods: Retinoic acid was used to induce the differentiation of NT2 ce...Objective: To evaluate the effect of salidroside on oxygen and glucose deprivation(OGD)-treated NT2 cells and its underlying mechanisms of action.Methods: Retinoic acid was used to induce the differentiation of NT2 cells into neurons. The effects of salidroside on survival, apoptosis, inflammatory response, and oxidative stress of neurons undergoing OGD were evaluated. Using precursor cells as controls, the effect of salidroside on the differentiation progression of OGDtreated cells was evaluated. In addition, the effect of erastin, a ferroptosis inducer, on NT2 cells was examined to investigate the underlying mechanisms of neuroprotective action of salidroside.Results: Salidroside alleviated the effects of OGD on neuronal survival, apoptosis, inflammation, and oxidative stress, and promoted NT2 cell differentiation. Moreover, salidroside prevented ferroptosis of OGD-treated cells, which was abolished following erastin treatment, indicating that ferroptosis mediated the regulatory pathway of salidroside.Conclusions: Salidroside attenuates OGD-induced neuronal injury by inhibiting ferroptosis and promotes neuronal differentiation.展开更多
Microstructural evolution and its effect on mechanical properties in different regions of 2219-C10S aluminum alloy tungsten inert gas(TIG)welded joint were analyzed in detail.In weld zone(WZ),α+θeutectic structure f...Microstructural evolution and its effect on mechanical properties in different regions of 2219-C10S aluminum alloy tungsten inert gas(TIG)welded joint were analyzed in detail.In weld zone(WZ),α+θeutectic structure formed at grain boundaries with no precipitates inside the grains.In partially melted zone(PMZ),symbiotic eutectic or divorced eutectic formed at grain boundaries and needle-likeθ′phases appeared in the secondary heated zone.In over aged zone(OAZ),the coarsening and dissolution ofθ′phases occurred and mostθ′phases transformed intoθphases.In general heat affected zone(HAZ),θ′phases coarsened.Factors such as the strengthening phases,the grain size,the Cu content in matrix and the dislocation density can affect the mechanical properties in different regions of the joint.Moreover,a model describing the relationship between mechanical properties of the material and the volume fraction of precipitates,the average diameter of precipitates and the concentration of soluble elements was proposed.展开更多
Background： Propofol is increasingly nsed during partial support mechanical ventilation such as pressure support ventilation （PSV） in postoperative patients. However breathing pattern, respiratory drive, and patien...Background： Propofol is increasingly nsed during partial support mechanical ventilation such as pressure support ventilation （PSV） in postoperative patients. However breathing pattern, respiratory drive, and patient-ventilator synchrony are affected by the sedative used and the sedation depth. The present study aimed to evaluate the physiologic effects of varying depths ofpropofbl sedation oll respiratory drive and patient-ventilator synchrony during PSV in postoperative patients. Methods： Eight postoperative patients receiving PSV for 〈24 h were enrolled. Propofol was administered to achieve and maintain a Ramsay score of 4, and the inspiratory pressure support was titrated to obtain a tidal volume （VT） of 6-8 ml/kg. Then, tile propolbl dose was reduced to achieve and maintain a Ramsay score of 3 and then 2. At each Ramsay level, the patient underwent 30-rain trials of PSV. We measured the electrical activity of the diaphragm, flow, airway presstlre, neuro-ventilatory efficiency （NVE）, and patient-ventilator synchrony. Results： Increasing the depth of sedation reduced the peak and mean electrical activity of the diaphragm, which suggested a decrease in respiratory drive, while VT remained unchanged. The NVE increased with an increase in the depth of sedation. Minute ventilation and inspiratory duty cycle decreased with an increase in the depth of sedation, but this only achieved statistical significance between Ramsay 2 and both Ramsay 4 and 3 （P 〈 0.05）. The ineffective triggering index increased with increasing sedation depth （9.5 -4- 4.0%, 6.7 - 2.0%, and 4.2-2.1% for Ramsay 4, 3, and 2, respectively） and achieved statistical significance between each pair of depth of sedation （P 〈 0.05）. The depth of sedation did not affect gas exchange. Conclusions： Propofol inhibits respiratory drive and deteriorates patient-ventilator synchrony to tile extent that varies with tile depth of sedation. Propolbl has less effect on breathing pattern and has no effect on VT and gas exchange in postoperative patients with PSV.展开更多
Background： Contribution of model for end-stage liver disease incorporating with serum sodium （MELD-Na） score in predicting acute kidney injury （AKI） after orthotopic liver transplantation （OLT） is yet to be id...Background： Contribution of model for end-stage liver disease incorporating with serum sodium （MELD-Na） score in predicting acute kidney injury （AKI） after orthotopic liver transplantation （OLT） is yet to be identified. This study assessed the prognostic value ot MELD-Na score for the development of AKl following OLT. Methods： Preoperative and surgery-related variables of 321 adult end-stage liver disease patients who underwent OLT in Fuzhou General Hospital were collected. PostoperativeAKI was defined and staged in accordance with the clinical practice guidelines developed by Kidney Disease： Improving Global Outcomes. Univariate and multivariate analysis was performed to determine the risk factors fnr AKI following OLT. The discriminating power of MELD/MELD-Na score on AKI outcome was evaluated by receiver operating characteristic （ROC） curve. Spearman＇s correlation analysis was used for identifying the correlated relationship between MELD/MELD-Na score and the severity levels of AKI. Results： The prevalence of AKI following OLT was in 206 out of 321 patients （64.2%）. Three risk lhctors for AKI post-OLT were presented, preoperative calculated MELD score （odds ratio [OR] = 1.048, P = 0.021）, intraoperative volume of red cell suspension transfusion （OR = 1.001, P 0.002）, and preoperative liver cirrhosis （OR = 2.015, P = 0.012）. Two areas under ROC curve （AUCs） of MELD/MELD-Na score predicting AKI were 0.688 and 0.672, respectively; the difference between two AUCs was not significant （Z= 1.952, P = 0.051）. The Spearman＇s correlation coefficients between MELD/MELD-Na score and the severity levels of AKI were 0.406 and 0.385 （P 0.001, 0.001）, respectively. Conclusions： We demonstrated that preoperative MELD score, intraoperative volume of red cell suspension transfusion and preoperative liver cirrhosis were risk factors for AKI following OLT. Furthermore, we preliminarily validated that MELD score seemed to have a stronger power discriminating AKI post-OLT than that of novel MELD-Na score.展开更多
A limnological study was carried out to determine the responses of superoxide dismutase （SOD） activities and soluble protein （SP） contents of 11 common aquatic plants to eutrophication stress. Field investigation ...A limnological study was carried out to determine the responses of superoxide dismutase （SOD） activities and soluble protein （SP） contents of 11 common aquatic plants to eutrophication stress. Field investigation in 12 lakes in the middle and lower reaches of the Yangtze River was carried out from March to September 2004. Our results indicated that non- submersed （emergent and floating-leafed） plants and submersed plants showed different responses to eutrophication stress. Both SOD activities of the non-submersed and submersed plants were negatively correlated with their SP contents （P 〈 0.000 1）. SP contents of non-submersed plants were significantly correlated with all nitrogen variables in the water （P 〈 0.05）, whereas SP contents of submersed plants were only significantly correlated with carbon variables as well as ammonium and Secchi depth （SD） in water （P 〈 0.05）. Only SOD activities of submersed plants were decreased with decline of SD in water （P 〈 0.001）. Our results indicate that the decline of SOD activities of submersed plants were mainly caused by light limitation, this showed a coincidence with the decline of macrophytes in eutrophic lakes, which might imply that the antioxidant system of the submersed plants were impaired under eutrophication stress.展开更多
Background:The effects of biodiversity on community function and services are frequently studied in the history of ecology,while the response of individual species to biodiversity remains great elusive.In this study,w...Background:The effects of biodiversity on community function and services are frequently studied in the history of ecology,while the response of individual species to biodiversity remains great elusive.In this study,we determined the biodiversity effects on community productivity as well as species level plant mass and carbon(C)and nitrogen(N)metabolism of eight submerged plants.These macrophytes in Lake Erhai were selected and planted in a water depth of one meter along a diversity gradient of 1,2,4 or 8 species.Then,the community productivity or species level plant mass,soluble protein,free amino acid and soluble carbohydrate were correlated to species richness to determine the biodiversity effects on community and single species.Results:The results showed that the community level biomass was positively correlated to plant species richness although the species level plant mass of individual species responded differently to the overall plant species richness.Namely,only one plant mass positively correlated to species richness and the others decreased or showed no significant correlation with the increase of species richness.The soluble proteins of most macrophytes were positively correlated to species richness;however,both the free amino acid and soluble carbohydrate of the plants were negatively or not significantly correlated to species richness.Conclusions:These results indicated that the selection effects might dominate in our aquatic communities and the negative impacts of biodiversity on C and N metabolism of the macrophytes increased with the increase of species richness,which might result from the strong competition among the studied species.The biodiversity effects on the plant mass,and C and N metabolism of individual submerged species were first reported in this study,while more such field and control experiments deserve further research.展开更多
基金supported by the National Natural Science Foundation of China(32370703)the CAMS Innovation Fund for Medical Sciences(CIFMS)(2022-I2M-1-021,2021-I2M-1-061)the Major Project of Guangzhou National Labora-tory(GZNL2024A01015).
文摘Viral infectious diseases,characterized by their intricate nature and wide-ranging diversity,pose substantial challenges in the domain of data management.The vast volume of data generated by these diseases,spanning from the molecular mechanisms within cells to large-scale epidemiological patterns,has surpassed the capabilities of traditional analytical methods.In the era of artificial intelligence(AI)and big data,there is an urgent necessity for the optimization of these analytical methods to more effectively handle and utilize the information.Despite the rapid accumulation of data associated with viral infections,the lack of a comprehensive framework for integrating,selecting,and analyzing these datasets has left numerous researchers uncertain about which data to select,how to access it,and how to utilize it most effectively in their research.This review endeavors to fill these gaps by exploring the multifaceted nature of viral infectious diseases and summarizing relevant data across multiple levels,from the molecular details of pathogens to broad epidemiological trends.The scope extends from the micro-scale to the macro-scale,encompassing pathogens,hosts,and vectors.In addition to data summarization,this review thoroughly investigates various dataset sources.It also traces the historical evolution of data collection in the field of viral infectious diseases,highlighting the progress achieved over time.Simultaneously,it evaluates the current limitations that impede data utilization.Furthermore,we propose strategies to surmount these challenges,focusing on the development and application of advanced computational techniques,AI-driven models,and enhanced data integration practices.By providing a comprehensive synthesis of existing knowledge,this review is designed to guide future research and contribute to more informed approaches in the surveillance,prevention,and control of viral infectious diseases,particularly within the context of the expanding big-data landscape.
文摘Parkinson’s disease patients,in addition to typical motor symptoms,often experience various psychological symptoms,including depression,anxiety,cognitive impairment,impulse control disorders,and psychotic symptoms.These symptoms severely affect patients’quality of life and may even cause a greater disease burden than motor symptoms.This review focuses on the application progress of transcranial magnetic stimulation(TMS)as a non-invasive neuromodulation technique in the treatment of psychological symptoms in Parkinson’s disease.Studies have shown that repetitive TMS(rTMS)has significant improvement effects on Parkinson’s disease-related depressive symptoms,with mechanisms possibly related to the regulation of the prefrontal-striatal dopamine pathway and the promotion of neuroplasticity.For anxiety symptoms,continuous theta burst stimulation has shown potential in indirect regulation of the amygdala and hippocampal regions.For cognitive impairment,high-frequency rTMS applied to the dorsolateral prefrontal cortex can improve executive function deficits,while bilateral coordinated stimulation protocols help enhance attention and memory functions.For impulse control disorders in Parkinson’s disease patients,inhibitory stimulation applied to the orbitofrontal cortex can alleviate pathological gambling and compulsive behaviors.In terms of sleep disorders,TMS has also shown potential efficacy in regulating circadian rhythms and improving rapid eye movement sleep behavior disorder.However,current research still has limitations such as small sample sizes,non-standardized stimulation protocols,and insufficient evaluation of long-term efficacy.Future research directions should focus on optimizing stimulation parameters,exploring individualized treatment protocols,integrating multimodal imaging assessments,and conducting large-sample randomized controlled trials to clarify the clinical application value of TMS in the rehabilitation of psychological symptoms in Parkinson’s disease,providing new approaches for the comprehensive management of this common neurodegenerative disease.
基金the financial support from the National Science and Technology Major Project of China (No. J2019-VI-0004-0117)National Natural Science Foundation of China (No. 51905301)。
基金Project(CALT201309)supported by Joint Innovation Fund for China Academy of Launch Vehicle Technology and Colleges
文摘In order to estimate the residual stresses in Ti2AlNb alloy jointed by electron beam welding (EBW), a computational approach based on finite element method was developed. Meanwhile, experiments were carried out to verify the numerical results. The comparison between the simulation results and measurements suggests that the developed computational approach has sufficient accuracy to predict the welding residual stress distributions. The results show that the central area of the fusion zone suffers tensile stresses in three directions. When the other parameters remain unchanged, the focus current has great impact on the weld shape and size, and then affects the residual stress level significantly. Moreover, the thick plate full-penetrated EBW weld suffers near 1000 MPa tensile stress of Z-direction in the center of the fusion zone. The wider weld has lower tensile stress in Z-direction, resulting in lower risk for cracking.
基金Project(U1637601)supported by the Joint Funds of the National Natural Science Foundation of China
文摘Numerical simulation and experimental methods were used to investigate the effects of weld penetration on tensile properties of 2219 aluminum alloy tungsten inert gas(TIG)welded joints.The results show that when other geometric parameters are consistent,within a certain range,the deeper the weld penetration of the capping weld is,the lower the tensile strength of the j oint is.The deeper weld penetration of the capping weld can cause the more concentrated stress at the weld toe and the joint is more likely to crack accordingly.Based on necessary assumptions,a model for analyzing the mathematical relation between the weld penetration of the capping weld and the tensile strength of the joint was proposed to validate the experimental results. The decrease of weld penetration of capping weld can be controlled by decreasing welding current,helium content or increasing welding voltage.
文摘In order to clarify the characteristics and formation mechanism of the reheat cracking in Ti2AlNb weldments,a series of heat treatment conditions were performed to the circular joints welded by electron beam,and then the macrostructures and microstructures were investigated using optical microscopy,scanning electron microscopy,X-ray diffractometry,and transmission electron microscopy.The results show that the reheat cracking occurs primarily along the grain boundaries in the weld when the Ti2AlNb circular welded joints are heated up to about 700℃.During the heat treatment,an almost complete transformation of B2→O happens while the temperature goes up through the O single-phase region.Then,O→B2+O phase transformation occurs primarily along the grain boundaries as the weld metal continues to heat up to the B2+O dual-phase region.Under the high tension stress consisting of welding residual stress and phase transformation stress,reheat cracking occurs at the interface between the B2+O dual-phase layer and the O-phase matrix.
基金the financial support from the National Key Technologies Research & Development Program of China (No. 2018YFB1106000)the Youth Talent Project of CAST (No. 2019QNRC001)。
文摘Wall structures were made by cold metal transfer-based wire and arc additive manufacturing using two kinds of ER2319 welding wires with and without Cd elements. T6 heat treatment was used to improve mechanical properties of these wall structures. Due to the higher vacancy binding energy of Cd, Cd-vacancy clusters are formed in the aging process and provide a large number of nucleation locations for θ′ phases. The higher diffusion coefficient of the Cd-vacancy cluster and the lower interfacial energy of θ′ phase lead to the formation of dense θ′ phases in the heat-treated α(Al). According to the strengthening model, after adding Cd in ER2319 welding wires, the yield strength increases by 43 MPa in the building direction of the heat-treated wall structures.
基金supported by the Joint Funds of the National Natural Science Foundation of China (Grant No. U1637601)
文摘In as-welded state,each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases.After the post-weld heat treatment,both the amount and the size of the eutectic structure orθphases decreased.Correspondingly,both the Cu content inα-Al matrix and the microhardness increased to a similar level in each region of the joint,and the tensile strength of the entire joint was greatly improved.Post-weld heat treatment played the role of solid solution strengthening and aging strengthening.After the post-weld heat treatment,the weld performance became similar to other regions,but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect.The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties,and the specimens randomly crack in the weld zone.
文摘AIM： To investigate the clinicopathological features of gastrointestinal stromal tumor （GIST） and to study the reference indexes for malignancy. METHODS： Fifty-two cases of primary GIST were distinguished from a group of gastrointestinal mesenchymal tumors using a panel of antibodies such as CD117 and CD34 by immunohistochemical SP method. Their biological behaviors were analyzed using the expression of p21WAF1 and Bax in 52 cases of GIST. RESULTS： Grossly, the tumor size was between 1.5 cm and 13 cm （mean： 5.5 cm）. Focal areas of hemorrhage, necrosis, or small cyst formation could be seen. Microscopically, the tumor was composed of spindle cells （20 cases）, epithelioid cells （20 cases） and mixed cells （12 cases）. Immunohistochemically, CDl17 and CD34 showed diffuse strong positive expressions, the positive rates were 98.1% and 92.3%. SMA, S-100, NSE, NF and MBP showed focal positive expressions, the positive rates were 48.1%, 28.8%, 25%, 21.2% and 42.3% respectively. Vimentins were all positive desmin and CgA were all negative. In normal adult stomach and intestine, the immunoreactive staining for CD117 and CD34 showed immunoreactive interstitial cells of Cajal in myenteric neuroplexus. Among the 52 cases of GIST, 27 were positive for p21WAF1 （51.9%）, 29 for Bax （55.8%）. The expression of p21WAF1 and Bax had no significent difference with the localization, size, histological subtype of GIST, but had a significent difference with the histological grade （P = 0.000, respectively）, p21WAF1 expression had a positive correlation to Bax expression （r = 0.461, P = 0.001, k = 0.459）. CONCLUSION： GIST has complicated arrangements and various cell types. Positivity of CD117 and CD34 is the most valuable factor in diagnosing GIST. Expression of p21WAF1 and Bax plays an important role in potential malignancy and malignancy rather than in benign GIST. p21WAF1 and Bax may be used as the markers in the assessment of GIST malignant potential.
基金Project(51375260) supported by the National Natural Science Foundation of China
文摘Transient liquid phase(TLP)bonding is a potential high-temperature(HT)electron packaging technology that is used inthe interconnection of wide band-gap semiconductors.This study focused on the mechanism of intermetallic compounds(IMCs)evolution in Ag/Sn TLP soldering at different temperatures.Experimental results indicated that morphologies of Ag3Sn grains mainlywere scallop-type,and some other shapes such as prism,needle,hollow column,sheet and wire of Ag3Sn grains were also observed,which was resulted from their anisotropic growths.However,the scallop-type Ag3Sn layer turned into more planar with prolongingsoldering time,due to grain coarsening and anisotropic mass flow of Ag atoms from substrate.Furthermore,a great amount ofnano-Ag3Sn particles were found on the surfaces of Ag3Sn grains,which were formed in Ag-rich areas of the molten Sn and adsorbedby the Ag3Sn grains during solidification process.Growth kinetics of the Ag3Sn IMCs in TLP soldering followed a parabolicrelationship with soldering time,and the growth rate constants of250,280and320°C were calculated as5.83×10-15m2/s,7.83×10-15m2/s and2.83×10-14m2/s,respectively.Accordingly,the activation energy of the reaction was estimated about58.89kJ/mol.
基金supported by the Zhejiang Traditional Chinese Medicine Science and Technology Plan Project(2021ZB027,2023ZL267)Zhejiang Medical and Health Platform Project of China(2019KY002,2019RC092).
文摘Objective: To evaluate the effect of salidroside on oxygen and glucose deprivation(OGD)-treated NT2 cells and its underlying mechanisms of action.Methods: Retinoic acid was used to induce the differentiation of NT2 cells into neurons. The effects of salidroside on survival, apoptosis, inflammatory response, and oxidative stress of neurons undergoing OGD were evaluated. Using precursor cells as controls, the effect of salidroside on the differentiation progression of OGDtreated cells was evaluated. In addition, the effect of erastin, a ferroptosis inducer, on NT2 cells was examined to investigate the underlying mechanisms of neuroprotective action of salidroside.Results: Salidroside alleviated the effects of OGD on neuronal survival, apoptosis, inflammation, and oxidative stress, and promoted NT2 cell differentiation. Moreover, salidroside prevented ferroptosis of OGD-treated cells, which was abolished following erastin treatment, indicating that ferroptosis mediated the regulatory pathway of salidroside.Conclusions: Salidroside attenuates OGD-induced neuronal injury by inhibiting ferroptosis and promotes neuronal differentiation.
基金Project(U1637601)supported by the Joint Funds of the National Natural Science Foundation of China。
文摘Microstructural evolution and its effect on mechanical properties in different regions of 2219-C10S aluminum alloy tungsten inert gas(TIG)welded joint were analyzed in detail.In weld zone(WZ),α+θeutectic structure formed at grain boundaries with no precipitates inside the grains.In partially melted zone(PMZ),symbiotic eutectic or divorced eutectic formed at grain boundaries and needle-likeθ′phases appeared in the secondary heated zone.In over aged zone(OAZ),the coarsening and dissolution ofθ′phases occurred and mostθ′phases transformed intoθphases.In general heat affected zone(HAZ),θ′phases coarsened.Factors such as the strengthening phases,the grain size,the Cu content in matrix and the dislocation density can affect the mechanical properties in different regions of the joint.Moreover,a model describing the relationship between mechanical properties of the material and the volume fraction of precipitates,the average diameter of precipitates and the concentration of soluble elements was proposed.
文摘Background： Propofol is increasingly nsed during partial support mechanical ventilation such as pressure support ventilation （PSV） in postoperative patients. However breathing pattern, respiratory drive, and patient-ventilator synchrony are affected by the sedative used and the sedation depth. The present study aimed to evaluate the physiologic effects of varying depths ofpropofbl sedation oll respiratory drive and patient-ventilator synchrony during PSV in postoperative patients. Methods： Eight postoperative patients receiving PSV for 〈24 h were enrolled. Propofol was administered to achieve and maintain a Ramsay score of 4, and the inspiratory pressure support was titrated to obtain a tidal volume （VT） of 6-8 ml/kg. Then, tile propolbl dose was reduced to achieve and maintain a Ramsay score of 3 and then 2. At each Ramsay level, the patient underwent 30-rain trials of PSV. We measured the electrical activity of the diaphragm, flow, airway presstlre, neuro-ventilatory efficiency （NVE）, and patient-ventilator synchrony. Results： Increasing the depth of sedation reduced the peak and mean electrical activity of the diaphragm, which suggested a decrease in respiratory drive, while VT remained unchanged. The NVE increased with an increase in the depth of sedation. Minute ventilation and inspiratory duty cycle decreased with an increase in the depth of sedation, but this only achieved statistical significance between Ramsay 2 and both Ramsay 4 and 3 （P 〈 0.05）. The ineffective triggering index increased with increasing sedation depth （9.5 -4- 4.0%, 6.7 - 2.0%, and 4.2-2.1% for Ramsay 4, 3, and 2, respectively） and achieved statistical significance between each pair of depth of sedation （P 〈 0.05）. The depth of sedation did not affect gas exchange. Conclusions： Propofol inhibits respiratory drive and deteriorates patient-ventilator synchrony to tile extent that varies with tile depth of sedation. Propolbl has less effect on breathing pattern and has no effect on VT and gas exchange in postoperative patients with PSV.
基金This study was supported by grants from Fujian Province Science and Technology Program （No. 2015Y0026） and Science and Technology Programs of Natural Science Foundation （No. 2016J01585）.
文摘Background： Contribution of model for end-stage liver disease incorporating with serum sodium （MELD-Na） score in predicting acute kidney injury （AKI） after orthotopic liver transplantation （OLT） is yet to be identified. This study assessed the prognostic value ot MELD-Na score for the development of AKl following OLT. Methods： Preoperative and surgery-related variables of 321 adult end-stage liver disease patients who underwent OLT in Fuzhou General Hospital were collected. PostoperativeAKI was defined and staged in accordance with the clinical practice guidelines developed by Kidney Disease： Improving Global Outcomes. Univariate and multivariate analysis was performed to determine the risk factors fnr AKI following OLT. The discriminating power of MELD/MELD-Na score on AKI outcome was evaluated by receiver operating characteristic （ROC） curve. Spearman＇s correlation analysis was used for identifying the correlated relationship between MELD/MELD-Na score and the severity levels of AKI. Results： The prevalence of AKI following OLT was in 206 out of 321 patients （64.2%）. Three risk lhctors for AKI post-OLT were presented, preoperative calculated MELD score （odds ratio [OR] = 1.048, P = 0.021）, intraoperative volume of red cell suspension transfusion （OR = 1.001, P 0.002）, and preoperative liver cirrhosis （OR = 2.015, P = 0.012）. Two areas under ROC curve （AUCs） of MELD/MELD-Na score predicting AKI were 0.688 and 0.672, respectively; the difference between two AUCs was not significant （Z= 1.952, P = 0.051）. The Spearman＇s correlation coefficients between MELD/MELD-Na score and the severity levels of AKI were 0.406 and 0.385 （P 0.001, 0.001）, respectively. Conclusions： We demonstrated that preoperative MELD score, intraoperative volume of red cell suspension transfusion and preoperative liver cirrhosis were risk factors for AKI following OLT. Furthermore, we preliminarily validated that MELD score seemed to have a stronger power discriminating AKI post-OLT than that of novel MELD-Na score.
基金Supported by the National Natural Science Foundation of China(30570280)the National Basic Research Program of China(2002CB412300,2002AA601011).
文摘A limnological study was carried out to determine the responses of superoxide dismutase （SOD） activities and soluble protein （SP） contents of 11 common aquatic plants to eutrophication stress. Field investigation in 12 lakes in the middle and lower reaches of the Yangtze River was carried out from March to September 2004. Our results indicated that non- submersed （emergent and floating-leafed） plants and submersed plants showed different responses to eutrophication stress. Both SOD activities of the non-submersed and submersed plants were negatively correlated with their SP contents （P 〈 0.000 1）. SP contents of non-submersed plants were significantly correlated with all nitrogen variables in the water （P 〈 0.05）, whereas SP contents of submersed plants were only significantly correlated with carbon variables as well as ammonium and Secchi depth （SD） in water （P 〈 0.05）. Only SOD activities of submersed plants were decreased with decline of SD in water （P 〈 0.001）. Our results indicate that the decline of SOD activities of submersed plants were mainly caused by light limitation, this showed a coincidence with the decline of macrophytes in eutrophic lakes, which might imply that the antioxidant system of the submersed plants were impaired under eutrophication stress.
基金supported by the National Natural Science Foundation of China(Nos.31301725,41401358 and 31200427)Hunan Provincial Natural Science Foundation(No.2018JJ2162)the Special Foundation for National Science and Technology Basic Research Program of China(2019FY102000).
文摘Background:The effects of biodiversity on community function and services are frequently studied in the history of ecology,while the response of individual species to biodiversity remains great elusive.In this study,we determined the biodiversity effects on community productivity as well as species level plant mass and carbon(C)and nitrogen(N)metabolism of eight submerged plants.These macrophytes in Lake Erhai were selected and planted in a water depth of one meter along a diversity gradient of 1,2,4 or 8 species.Then,the community productivity or species level plant mass,soluble protein,free amino acid and soluble carbohydrate were correlated to species richness to determine the biodiversity effects on community and single species.Results:The results showed that the community level biomass was positively correlated to plant species richness although the species level plant mass of individual species responded differently to the overall plant species richness.Namely,only one plant mass positively correlated to species richness and the others decreased or showed no significant correlation with the increase of species richness.The soluble proteins of most macrophytes were positively correlated to species richness;however,both the free amino acid and soluble carbohydrate of the plants were negatively or not significantly correlated to species richness.Conclusions:These results indicated that the selection effects might dominate in our aquatic communities and the negative impacts of biodiversity on C and N metabolism of the macrophytes increased with the increase of species richness,which might result from the strong competition among the studied species.The biodiversity effects on the plant mass,and C and N metabolism of individual submerged species were first reported in this study,while more such field and control experiments deserve further research.
