Deficiency in executive functioning is a core symptom of attention deficit hyperactivity disorder (ADHD). The brain part responsible for executive functions is the prefrontal cortex (PFC). Although drug-based interven...Deficiency in executive functioning is a core symptom of attention deficit hyperactivity disorder (ADHD). The brain part responsible for executive functions is the prefrontal cortex (PFC). Although drug-based interventions can improve PFC activity, reports on PFC activity being improved by behavioral treatment are lacking. We evaluated whether a summer treatment program (STP) administering comprehensive behavioral treatment would increase PFC activity in children with ADHD. We examined behavioral and neural changes in 20 children before and after the STP, conducted over a 2-week period. We asked the parents/guardians to complete the Swanson, Nolan, and Pelham IV scale to assess severity of ADHD. The main task evaluating executive control was the reverse Stroop task. To examine changes in physiological indices, we used near-infrared spectroscopy to measure changes in PFC activity. Subjective assessments by parents/guardians indicated that ADHD symptoms improved significantly. There was also significant improvement in the number of correct responses and interference rates in the reverse Stroop task. Furthermore, post-intervention PFC activity was significantly higher. These results suggest that the STP improved inhibitory control in executive function, which is considered as a key symptom of ADHD. The increase in PFC activity further suggests that the STP improves cognition through neural function.展开更多
Background: Even though domestic violence is a major problem, only a few studies have examined the long term sustainability of treatment for men who voluntarily seek help to stop their violent behavior towards intimat...Background: Even though domestic violence is a major problem, only a few studies have examined the long term sustainability of treatment for men who voluntarily seek help to stop their violent behavior towards intimate partners. Women are exposed to a much greater degree of serious violence and sexual abuse compared to men. Objective: The aim of this study was to identify which elements of the treatment program batterers found most useful four to seven years after program completion. Design: The participants consisted of a sample of men who had gone through anger management therapy four to seven years previously. Data on violence were collected through self-report before and four to seven years after treatment, using a modified version of the Conflict Tactics Scales. Results: The decrease in physical violence was statistically significant: t (36) = 8.43, p < 0.001 with a large effect size (eta squared = 0.66). Psychological violence also decreased significantly: t (36) = 9.21, p < 0.001 with a large effect size (eta squared = 0.7). The results indicate that the most important anger management techniques were extensively applied in former patients of the anger management treatment program. In total, about two out of three patients still used the techniques after ending treatment four to seven years earlier.展开更多
The deformation behavior and formability of gradient nano-grained(GNG) AISI 304 stainless steel in uniaxial and biaxial states were investigated by means of tensile test and small punch test(SPT). The GNG top laye...The deformation behavior and formability of gradient nano-grained(GNG) AISI 304 stainless steel in uniaxial and biaxial states were investigated by means of tensile test and small punch test(SPT). The GNG top layer was fabricated on coarse grains(CG) AISI 304 by ultrasonic impact treatment. The results showed that the CG substrate could effectively suppress the strain localization of NC in GNG layer, and an approximate linear relationship existed between the thickness of substrate(h) and uniform true strain before necking(ε_(unif)). Grain growth of NC was observed at the stress state with high Stress triaxiality T, which led to better ductility of GNG/CG 304 in SPT, as well as similar true strain after the onset of necking(ε_(neck)) compared with coarse 304 in tensile test. Ei-values of GNG/CG 304 with different structures were nearly the same at different punch speeds, and good formability of GNG/CG 304 was demonstrated. However, punch speed and microstructure needed to be optimized to avoid much lost of membrane strain region in biaxial stress state.展开更多
The superelastic behaviors of different isothermal treated Cu-13.SAl-4.ONi (mass fraction) single crystals were studied by applying tensile stress along <001> of the d phase. The different isothermal specimens h...The superelastic behaviors of different isothermal treated Cu-13.SAl-4.ONi (mass fraction) single crystals were studied by applying tensile stress along <001> of the d phase. The different isothermal specimens have different superelastic behavior due to the change of the ratio of stress-induced r1 and β1. The superelasticity of r1 phase tends to that of g; phase with cycling. Typical stabilization of stress-induced martensite above Ap results in residual deformation. Due to the reverse transformation of 7I, there is a deviation of pseudo-yield stress from linear relation with temperature at relatively low stress.展开更多
In Uganda, there is still insufficient comprehension of malaria as a lethal disease especially in rural areas despite universal bed-net distribution coverage and effective anti-malarial treatment. <strong>Aim:&l...In Uganda, there is still insufficient comprehension of malaria as a lethal disease especially in rural areas despite universal bed-net distribution coverage and effective anti-malarial treatment. <strong>Aim:</strong> To get evidence-based knowledge to establish the contribution of an individuals’ knowledge from various health communications that could increase their active involvement in health care especially seeking timely appropriate treatment for malaria or suspected malaria. <strong>Method:</strong> A cross-sectional survey using a correlational design was employed on a clustered sample of 380 rural households in 05 sub-counties of Kanungu district. Data were corrected between October 2016-January 2017 using researcher-administered questionnaires, key-informant interviews and focus group discussions. Correlation analysis was done. <strong>Result:</strong> There is a significant positive relationship between knowledge of health communications and treatment-seeking behavior (r = 0.312;<em>p</em> ≤ 0.01). <strong>Conclusion:</strong> Exposure to consistent Behavioral Change Communications messages influences treatment-seeking behaviour. Thus, in malaria-prone communities, it appears that other factors including sufficient targeted persuasive health communication are lacking in influencing personal orientations towards treatment-seeking behaviour. Therefore, proper Health Communications management supplements efforts from other disciplines and players, against malaria in Uganda.展开更多
AIM: To determine the clinical effectiveness of intense psychological support to physical activity (PA) in nonalcoholic fatty liver disease (NAFLD), compared with cognitive-behavioral treatment (CBT).
The objective of this study was to investigate the effect of a new combined micro/nanoscale implant surface feature on osteoblasts' behaviors including cell morphology, adhesion, proliferation, differentiation, and m...The objective of this study was to investigate the effect of a new combined micro/nanoscale implant surface feature on osteoblasts' behaviors including cell morphology, adhesion, proliferation, differentiation, and mineralization in vitro. A new micro/nano-hybrid topography surface was fabricated on commercial pure titanium(Cp Ti) by a two-step sandblasted acid-etching and subsequent alkali-and heattreatment(SA-AH). The conventional sandblasted/acid-etching(SA) treatment and alkali and heat(AH) treatment were also carried out on the Cp Ti as controls. Surface microstructures of the Ti disc samples were assessed by scanning electron microscopy(SEM). The neonatal rat calvaria-derived osteoblasts were seeded on these discs and the initial cell morphology was evaluated by SEM and immunofluorescence. Initial adhesion of the cells was then assayed by DAPI staining at 1, 2, and 4 h after seeding. The Cell Counting Kit-8(CCact K8) assay, gene expression of osteoblastic markers(ALP, Col 1, OCN, BSP, OSX, Cbfα1) and Alizarin Red S staining assays were monitored respectively for cell proliferations, differentiation and mineralization. The results show significant differences in osteoblast's behaviors on the four kinds of Ti surfaces. Compared with Cp Ti surface, the SA and AH treatment can significantly promote cell adhesion, differentiation and mineralization of osteoblasts. In particular, the combined SA and AH treatments exhibit synergistic effects in comparison with the treatment of SA and AH individually, and are more favorable for stimulating a series of osteogenous responses from cell adhesion to mineralization of osteoblasts. In summary, this study provides some new evidence that the integrated micro/nanostructure on the Cp Ti surface may promote bone osseointegration between the Ti implantbone interfaces in vitro.展开更多
Objective To analyze the spectrum of microbiological agents causing community-acquired pneumonia (CAP) in recent years. We also investigated the procedure of diagnosis us well as the empirical treatment for this dis...Objective To analyze the spectrum of microbiological agents causing community-acquired pneumonia (CAP) in recent years. We also investigated the procedure of diagnosis us well as the empirical treatment for this disease in OPD ( outpatient department) of pulmonary disease. Methods A total of 7097 patients from 150 hospitals in 24 provinces in China were enrolled in the study from Nov. 2002 to Mar. 2003. Every patient was diagnosed, treated and registered at the same time. Diagnostic behavior for doctors include chest radiograph and/or CT examination of the lung, as well as collecting sputum samples at the time of diagnosis for bacteria culture to identify the pathogen. Appointed staff fulfiUed the questionnaires and information sheets in each center. After that, data were computerized and analyzed. Results There were 7404 valid information sheets and 7097 questionnaires taken into count. The majority CAP patients were from cities ( 77. 3% ), most of those who had medical insurance. Most CAP patients had productive cough (81.1% ), and 76. 7% and 18. 2 % CAP patients received chest film and CT examination respectively for diagnosis. Only 24% patients received sputum sample tested and with 36% got positive results. Streptococcus pneumoniae remained the main pathogen of CAP (43. 2% ). Most doctors used to prescribe β-lactam antibiotics as the first line of empirical therapy of CAP ( 51.1% ) with oral taken as the main method for drug using (66. 3% ). Conclusion This survey provides a key point of empirical therapy in China. The procedure for diagnosing us well as the empirical treatment of CAP in OPD of pulmonary disease in China still to be improved, especially in accessing the pathogen. Guidelines developed to recognize and evaluate CAP should base on epidemiological information of the pathogen prevalence, then could offer a rational approach to the initial management of the CAP patients.展开更多
The migrants are the important participant and contributor in China’s economic and social construction,but they still have many restrictions on their access to health services.This paper analyzes the differences betw...The migrants are the important participant and contributor in China’s economic and social construction,but they still have many restrictions on their access to health services.This paper analyzes the differences between the migrants and the regis-tered local residents in looking for medical treatment and explores the relationship between health education and medical treatment seeking behavior,so as to find an appropriate way to improve the health level of the migrants.By using the compara-tive survey data of the floating population and registered population in 2017 and establishing the binary Logit model,this paper finds that the health education has a promoting effect on medical treatment seeking behaviors.In terms of the influence mechanism of health education on medical treatment seeking behavior,the mediat-ing effect of social participation factors is stronger in the migrants’group because making new friends and learning about local public health resources through health education is of great significance to the migrants.It is proposed to expand the cov-erage of health education among migrant groups and improve the accessibility of health education.At the same time,public medical and health services should be used as a window to guide the migrants to seek medical treatment in an orderly manner while assisting their social integration.展开更多
Surface oxidation can alter physicochemical properties of multiwalled carbon nanotubes(MWCNTs) and influence their aqueous stabilization.Many techniques have been used to characterize the physicochemical properties an...Surface oxidation can alter physicochemical properties of multiwalled carbon nanotubes(MWCNTs) and influence their aqueous stabilization.Many techniques have been used to characterize the physicochemical properties and aqueous stabilization of MWCNTs.However,the relationship between the change in physicochemical property and the aqueous stabilization of MWCNTs merits more studies,and the multiple characterization techniques have not been well compared.This study systematically and comparatively investigated the effect of oxidation on the physicochemical properties and aqueous stabilization of MWCNTs using multiple analysis methods.Increased surface area,disclosed tube ends,defects on the sidewalls,disruption of the electronic structure,and removal of metal catalysts and amorphous carbon were observed for the oxidized MWCNTs(o-MWCNTs) using the multipoint Brunauer-Emmett-Teller(BET) method,transmission electron microscope observation,Raman spectroscopy,UV-Vis spectroscopy,and thermogravimetric analysis.An oxidation-time-dependent increase in oxygen content of the MWCNTs was verified by the methods of elemental analysis,mass difference calculation,and X-ray photoelectron spectroscopy(XPS).Fourier transform infrared spectroscopy,XPS,and the Boehm titration were employed to study the functionalities on the MWCNT surfaces.Despite the limitations of these techniques,the results indicated that the dramatic increase in carboxyl groups was mainly responsible for the significant increase in oxygen content after the oxidation.The dissociation of the grafted functional groups increased electronegativity of the o-MWCNTs and facilitated the aqueous stabilization of o-MWCNTs through electrostatic repulsions.The oxidation affected the UV-Vis absorbance of MWCNT suspensions.The absorbances at 800 nm of the stabilized MWCNT suspensions had a good correlation with the MWCNT concentrations and could be used to quantify the MWCNT suspensions.The findings of this work are expected to boost the research on carbon nanotubes and their environmental behaviors.展开更多
In this research, the toxic effects of deltamethrin (DM) on the behavior responses of Zebra fish (Damo rerio) in the characteristic of behavior strength were investigated followed by an assessment of an in situ re...In this research, the toxic effects of deltamethrin (DM) on the behavior responses of Zebra fish (Damo rerio) in the characteristic of behavior strength were investigated followed by an assessment of an in situ remediation of the DM pollution using sodium percarbonate. Behavior strength ofDanio rerio was approximately 0.83 in the control group and was slightly higher than 0.83 in the sublethal treatment (0.1 TU (toxic unit)), which suggested that sublethal DM exposure could induce a stimulation effect in 48 h of exposure. In lower DM concentration treatments (0.5 and 1.0 TU), behavior strength could be inhibited significantly. Behavior responses of Danio rerio showed a gradually increased tendency when they were exposed to higher concentration of DM, and the declining amplitudes of behavior strength changed with the increase of DM concentrations. These results suggested that DM had evident acute toxicity effects on the behavior responses of Danio rerio with a good dose-effect relationship. The in situ remediation of the DM pollution using sodium percarhonate showed that the toxic effect of DM on behavior responses ofDanio rerio could be eliminated even in the highest concentration of DM (5.0 TU). Meanwhile, the behavior response of Danio rerio in the treatment of sodium percarbonate was the same as in the control, which indicated that sodium percarbonate had no evident toxic effects on the behavior of Daniu rerio in the current concentration. This study suggested that adding sodium percarbonate in situ might be a good way to eliminate the DM toxic effects.展开更多
This study investigates the cryogenic tensile properties and fracture behavior of fiction stir welded and post-weld heat-treated joints of 32Mn-7Cr-1Mo-0.3N steel. Cryogenic brittle fracture, which occurred in the as-...This study investigates the cryogenic tensile properties and fracture behavior of fiction stir welded and post-weld heat-treated joints of 32Mn-7Cr-1Mo-0.3N steel. Cryogenic brittle fracture, which occurred in the as-welded joint, is related to the residual particles that contain tungsten in the joint band structure. Post-weld water toughening resulted in the cryogenic intergranular brittleness of the joint, which is related to the non-equilibrium segregation of solute atoms during the post-weld water toughening. Annealing at 55OC for 30rain can effectively inhibit the cryogenic intergranular brittleness of the post- weld water-toughened joint. The yield strength, ultimate tensile strength, and uniform elongation of the annealed joint are approximately 95%, 87%, and 94% of the corresponding data of the base metal.展开更多
文摘Deficiency in executive functioning is a core symptom of attention deficit hyperactivity disorder (ADHD). The brain part responsible for executive functions is the prefrontal cortex (PFC). Although drug-based interventions can improve PFC activity, reports on PFC activity being improved by behavioral treatment are lacking. We evaluated whether a summer treatment program (STP) administering comprehensive behavioral treatment would increase PFC activity in children with ADHD. We examined behavioral and neural changes in 20 children before and after the STP, conducted over a 2-week period. We asked the parents/guardians to complete the Swanson, Nolan, and Pelham IV scale to assess severity of ADHD. The main task evaluating executive control was the reverse Stroop task. To examine changes in physiological indices, we used near-infrared spectroscopy to measure changes in PFC activity. Subjective assessments by parents/guardians indicated that ADHD symptoms improved significantly. There was also significant improvement in the number of correct responses and interference rates in the reverse Stroop task. Furthermore, post-intervention PFC activity was significantly higher. These results suggest that the STP improved inhibitory control in executive function, which is considered as a key symptom of ADHD. The increase in PFC activity further suggests that the STP improves cognition through neural function.
文摘Background: Even though domestic violence is a major problem, only a few studies have examined the long term sustainability of treatment for men who voluntarily seek help to stop their violent behavior towards intimate partners. Women are exposed to a much greater degree of serious violence and sexual abuse compared to men. Objective: The aim of this study was to identify which elements of the treatment program batterers found most useful four to seven years after program completion. Design: The participants consisted of a sample of men who had gone through anger management therapy four to seven years previously. Data on violence were collected through self-report before and four to seven years after treatment, using a modified version of the Conflict Tactics Scales. Results: The decrease in physical violence was statistically significant: t (36) = 8.43, p < 0.001 with a large effect size (eta squared = 0.66). Psychological violence also decreased significantly: t (36) = 9.21, p < 0.001 with a large effect size (eta squared = 0.7). The results indicate that the most important anger management techniques were extensively applied in former patients of the anger management treatment program. In total, about two out of three patients still used the techniques after ending treatment four to seven years earlier.
基金Funded by the National National Natural Science Foundation of China(No.51505189)Open Project of Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment&Technology(No.FM-2015-5)
文摘The deformation behavior and formability of gradient nano-grained(GNG) AISI 304 stainless steel in uniaxial and biaxial states were investigated by means of tensile test and small punch test(SPT). The GNG top layer was fabricated on coarse grains(CG) AISI 304 by ultrasonic impact treatment. The results showed that the CG substrate could effectively suppress the strain localization of NC in GNG layer, and an approximate linear relationship existed between the thickness of substrate(h) and uniform true strain before necking(ε_(unif)). Grain growth of NC was observed at the stress state with high Stress triaxiality T, which led to better ductility of GNG/CG 304 in SPT, as well as similar true strain after the onset of necking(ε_(neck)) compared with coarse 304 in tensile test. Ei-values of GNG/CG 304 with different structures were nearly the same at different punch speeds, and good formability of GNG/CG 304 was demonstrated. However, punch speed and microstructure needed to be optimized to avoid much lost of membrane strain region in biaxial stress state.
文摘The superelastic behaviors of different isothermal treated Cu-13.SAl-4.ONi (mass fraction) single crystals were studied by applying tensile stress along <001> of the d phase. The different isothermal specimens have different superelastic behavior due to the change of the ratio of stress-induced r1 and β1. The superelasticity of r1 phase tends to that of g; phase with cycling. Typical stabilization of stress-induced martensite above Ap results in residual deformation. Due to the reverse transformation of 7I, there is a deviation of pseudo-yield stress from linear relation with temperature at relatively low stress.
文摘In Uganda, there is still insufficient comprehension of malaria as a lethal disease especially in rural areas despite universal bed-net distribution coverage and effective anti-malarial treatment. <strong>Aim:</strong> To get evidence-based knowledge to establish the contribution of an individuals’ knowledge from various health communications that could increase their active involvement in health care especially seeking timely appropriate treatment for malaria or suspected malaria. <strong>Method:</strong> A cross-sectional survey using a correlational design was employed on a clustered sample of 380 rural households in 05 sub-counties of Kanungu district. Data were corrected between October 2016-January 2017 using researcher-administered questionnaires, key-informant interviews and focus group discussions. Correlation analysis was done. <strong>Result:</strong> There is a significant positive relationship between knowledge of health communications and treatment-seeking behavior (r = 0.312;<em>p</em> ≤ 0.01). <strong>Conclusion:</strong> Exposure to consistent Behavioral Change Communications messages influences treatment-seeking behaviour. Thus, in malaria-prone communities, it appears that other factors including sufficient targeted persuasive health communication are lacking in influencing personal orientations towards treatment-seeking behaviour. Therefore, proper Health Communications management supplements efforts from other disciplines and players, against malaria in Uganda.
基金Supported by European Community’s Seventh Framework Program(FP7/2007-2013)under grant agreement,No.HEALTH-F2-2009-241762 for the project FLIP(in part)Centis E,Nuccitelli C and Moscatiello S supported by specific research contracts within the same program
文摘AIM: To determine the clinical effectiveness of intense psychological support to physical activity (PA) in nonalcoholic fatty liver disease (NAFLD), compared with cognitive-behavioral treatment (CBT).
基金Funded by the Natural Science Fundation of Zhejiang Province(Nos.Y2080956 and Y4110169)the National Natural Science Foundation of China(Nos.51102211,and 20934003)the Science and Technique Plans of Wenzhou City(Nos.Y20070093 and H20100076)
文摘The objective of this study was to investigate the effect of a new combined micro/nanoscale implant surface feature on osteoblasts' behaviors including cell morphology, adhesion, proliferation, differentiation, and mineralization in vitro. A new micro/nano-hybrid topography surface was fabricated on commercial pure titanium(Cp Ti) by a two-step sandblasted acid-etching and subsequent alkali-and heattreatment(SA-AH). The conventional sandblasted/acid-etching(SA) treatment and alkali and heat(AH) treatment were also carried out on the Cp Ti as controls. Surface microstructures of the Ti disc samples were assessed by scanning electron microscopy(SEM). The neonatal rat calvaria-derived osteoblasts were seeded on these discs and the initial cell morphology was evaluated by SEM and immunofluorescence. Initial adhesion of the cells was then assayed by DAPI staining at 1, 2, and 4 h after seeding. The Cell Counting Kit-8(CCact K8) assay, gene expression of osteoblastic markers(ALP, Col 1, OCN, BSP, OSX, Cbfα1) and Alizarin Red S staining assays were monitored respectively for cell proliferations, differentiation and mineralization. The results show significant differences in osteoblast's behaviors on the four kinds of Ti surfaces. Compared with Cp Ti surface, the SA and AH treatment can significantly promote cell adhesion, differentiation and mineralization of osteoblasts. In particular, the combined SA and AH treatments exhibit synergistic effects in comparison with the treatment of SA and AH individually, and are more favorable for stimulating a series of osteogenous responses from cell adhesion to mineralization of osteoblasts. In summary, this study provides some new evidence that the integrated micro/nanostructure on the Cp Ti surface may promote bone osseointegration between the Ti implantbone interfaces in vitro.
文摘Objective To analyze the spectrum of microbiological agents causing community-acquired pneumonia (CAP) in recent years. We also investigated the procedure of diagnosis us well as the empirical treatment for this disease in OPD ( outpatient department) of pulmonary disease. Methods A total of 7097 patients from 150 hospitals in 24 provinces in China were enrolled in the study from Nov. 2002 to Mar. 2003. Every patient was diagnosed, treated and registered at the same time. Diagnostic behavior for doctors include chest radiograph and/or CT examination of the lung, as well as collecting sputum samples at the time of diagnosis for bacteria culture to identify the pathogen. Appointed staff fulfiUed the questionnaires and information sheets in each center. After that, data were computerized and analyzed. Results There were 7404 valid information sheets and 7097 questionnaires taken into count. The majority CAP patients were from cities ( 77. 3% ), most of those who had medical insurance. Most CAP patients had productive cough (81.1% ), and 76. 7% and 18. 2 % CAP patients received chest film and CT examination respectively for diagnosis. Only 24% patients received sputum sample tested and with 36% got positive results. Streptococcus pneumoniae remained the main pathogen of CAP (43. 2% ). Most doctors used to prescribe β-lactam antibiotics as the first line of empirical therapy of CAP ( 51.1% ) with oral taken as the main method for drug using (66. 3% ). Conclusion This survey provides a key point of empirical therapy in China. The procedure for diagnosing us well as the empirical treatment of CAP in OPD of pulmonary disease in China still to be improved, especially in accessing the pathogen. Guidelines developed to recognize and evaluate CAP should base on epidemiological information of the pathogen prevalence, then could offer a rational approach to the initial management of the CAP patients.
基金This study was funded by Jiangsu Provincial University Philosophy and Social Science Research Fund(grant number 2022SJYB0105).
文摘The migrants are the important participant and contributor in China’s economic and social construction,but they still have many restrictions on their access to health services.This paper analyzes the differences between the migrants and the regis-tered local residents in looking for medical treatment and explores the relationship between health education and medical treatment seeking behavior,so as to find an appropriate way to improve the health level of the migrants.By using the compara-tive survey data of the floating population and registered population in 2017 and establishing the binary Logit model,this paper finds that the health education has a promoting effect on medical treatment seeking behaviors.In terms of the influence mechanism of health education on medical treatment seeking behavior,the mediat-ing effect of social participation factors is stronger in the migrants’group because making new friends and learning about local public health resources through health education is of great significance to the migrants.It is proposed to expand the cov-erage of health education among migrant groups and improve the accessibility of health education.At the same time,public medical and health services should be used as a window to guide the migrants to seek medical treatment in an orderly manner while assisting their social integration.
基金supported by the National Natural Science Foundation of China(21525728,21337004,21477107)the National Basic Research Program of China(2014CB441104)the Specialized Research Fund for the Doctoral Program of Higher Education (20130101110132)
文摘Surface oxidation can alter physicochemical properties of multiwalled carbon nanotubes(MWCNTs) and influence their aqueous stabilization.Many techniques have been used to characterize the physicochemical properties and aqueous stabilization of MWCNTs.However,the relationship between the change in physicochemical property and the aqueous stabilization of MWCNTs merits more studies,and the multiple characterization techniques have not been well compared.This study systematically and comparatively investigated the effect of oxidation on the physicochemical properties and aqueous stabilization of MWCNTs using multiple analysis methods.Increased surface area,disclosed tube ends,defects on the sidewalls,disruption of the electronic structure,and removal of metal catalysts and amorphous carbon were observed for the oxidized MWCNTs(o-MWCNTs) using the multipoint Brunauer-Emmett-Teller(BET) method,transmission electron microscope observation,Raman spectroscopy,UV-Vis spectroscopy,and thermogravimetric analysis.An oxidation-time-dependent increase in oxygen content of the MWCNTs was verified by the methods of elemental analysis,mass difference calculation,and X-ray photoelectron spectroscopy(XPS).Fourier transform infrared spectroscopy,XPS,and the Boehm titration were employed to study the functionalities on the MWCNT surfaces.Despite the limitations of these techniques,the results indicated that the dramatic increase in carboxyl groups was mainly responsible for the significant increase in oxygen content after the oxidation.The dissociation of the grafted functional groups increased electronegativity of the o-MWCNTs and facilitated the aqueous stabilization of o-MWCNTs through electrostatic repulsions.The oxidation affected the UV-Vis absorbance of MWCNT suspensions.The absorbances at 800 nm of the stabilized MWCNT suspensions had a good correlation with the MWCNT concentrations and could be used to quantify the MWCNT suspensions.The findings of this work are expected to boost the research on carbon nanotubes and their environmental behaviors.
文摘In this research, the toxic effects of deltamethrin (DM) on the behavior responses of Zebra fish (Damo rerio) in the characteristic of behavior strength were investigated followed by an assessment of an in situ remediation of the DM pollution using sodium percarbonate. Behavior strength ofDanio rerio was approximately 0.83 in the control group and was slightly higher than 0.83 in the sublethal treatment (0.1 TU (toxic unit)), which suggested that sublethal DM exposure could induce a stimulation effect in 48 h of exposure. In lower DM concentration treatments (0.5 and 1.0 TU), behavior strength could be inhibited significantly. Behavior responses of Danio rerio showed a gradually increased tendency when they were exposed to higher concentration of DM, and the declining amplitudes of behavior strength changed with the increase of DM concentrations. These results suggested that DM had evident acute toxicity effects on the behavior responses of Danio rerio with a good dose-effect relationship. The in situ remediation of the DM pollution using sodium percarhonate showed that the toxic effect of DM on behavior responses ofDanio rerio could be eliminated even in the highest concentration of DM (5.0 TU). Meanwhile, the behavior response of Danio rerio in the treatment of sodium percarbonate was the same as in the control, which indicated that sodium percarbonate had no evident toxic effects on the behavior of Daniu rerio in the current concentration. This study suggested that adding sodium percarbonate in situ might be a good way to eliminate the DM toxic effects.
基金Financial support by State Key Lab of Advanced Welding and Joining,Harbin Institute of Technology
文摘This study investigates the cryogenic tensile properties and fracture behavior of fiction stir welded and post-weld heat-treated joints of 32Mn-7Cr-1Mo-0.3N steel. Cryogenic brittle fracture, which occurred in the as-welded joint, is related to the residual particles that contain tungsten in the joint band structure. Post-weld water toughening resulted in the cryogenic intergranular brittleness of the joint, which is related to the non-equilibrium segregation of solute atoms during the post-weld water toughening. Annealing at 55OC for 30rain can effectively inhibit the cryogenic intergranular brittleness of the post- weld water-toughened joint. The yield strength, ultimate tensile strength, and uniform elongation of the annealed joint are approximately 95%, 87%, and 94% of the corresponding data of the base metal.