Arson presents a challenging crime scene for fire investigators worldwide. Key to the investigation of suspected arson cases is the analysis of fire debris for the presence of accelerants or ignitable liquids. This st...Arson presents a challenging crime scene for fire investigators worldwide. Key to the investigation of suspected arson cases is the analysis of fire debris for the presence of accelerants or ignitable liquids. This study has investigated the application and method development of vapor phase mid-Infrared (mid-IR) spectroscopy using a field portable quantum cascade laser (QCL) based system for the detection and identification of accelerant residues such as gasoline, diesel, and ethanol in fire debris. A searchable spectral library of various ignitable fluids and fuel components measured in the vapor phase was constructed that allowed for real-time identification of accelerants present in samples using software developed in-house. Measurement of vapors collected from paper material that had been doused with an accelerant followed by controlled burning and then extinguished with water showed that positive identification could be achieved for gasoline, diesel, and ethanol. This vapor phase mid-IR QCL method is rapid, easy to use, and has the sensitivity and discrimination capability that make it well suited for non-destructive crime scene sample analysis. Sampling and measurement can be performed in minutes with this 7.5 kg instrument. This vibrational spectroscopic method required no time-consuming sample pretreatment or complicated solvent extraction procedure. The results of this initial feasibility study demonstrate that this portable fire debris analyzer would greatly benefit arson investigators performing analysis on-site.展开更多
Background: Since the greater part of coronary blood flow takes place during the diastolic phase of each cardiac cycle, a time indicator of myocardial perfusion reserve, the ratio of diastolic to systolic duration (D/...Background: Since the greater part of coronary blood flow takes place during the diastolic phase of each cardiac cycle, a time indicator of myocardial perfusion reserve, the ratio of diastolic to systolic duration (D/S ratio), was presented. The objective of this study was to evaluate the accuracy and precision, the biological implication, and the applications of D/S ratio. Methods: Multi-center pragmatic studies evaluating the time indicator of cardiac perfusion reserve were performed. Related experiments, clinical trials, and surveys were conducted at 5 centers. Results: The results showed that the measurement of D/S ratio is both accurate and precise;the mean values of D/S of all of the 3 species studied (human, rabbit, and rat) were greater than 1. These application studies on D/S ratio showed that a close negative correlation existed between D/S ratio and New York Heart Association Functional Classification (NYHA FC) (r = –0.659, p pregnant women with pre-eclampsia and either normal pregnant women or non-pregnant women were significant (p Conclusions: D/S ratio has important biological implication, which is a safe, easy, reliable, and effective indicator, can be used to evaluate fitness levels, served as a pathophysiological marker for screening of cardiovascular disease (CVD), for predicting risk of cardiac events, and for evaluating the severity and prognosis of CVD.展开更多
BACKGROUND:Resovist,a superparamagnetic iron oxide,can be used to label neural stem cells(NSCs).Magnetic resonance tracking of superparamagnetic iron oxide-labeled NSCs is a non-invasive technique to track transplante...BACKGROUND:Resovist,a superparamagnetic iron oxide,can be used to label neural stem cells(NSCs).Magnetic resonance tracking of superparamagnetic iron oxide-labeled NSCs is a non-invasive technique to track transplanted NSCs following focal cerebral ischemia.OBJECTIVE:To observe survival and migration of transplanted NSCs in a rat model of focal ischemia/reperfusion using magnetic resonance imaging(MRI).DESIGN,TIME AND SETTING:An in vitro,in vivo,tracking study was performed at the Basic Laboratory of Harbin Medical University and the Room of MRI,Second Affiliated Hospital of Harbin Medical University,China from December 2006 to December 2009.MATERIALS:Resovist(Schering,Germany) and Achieva 1.5TMR imaging system(Philips,Amsterdam,the Netherlands) were utilized in the present study.METHODS:NSCs were harvested from brain tissues of neonatal Sprague Dawley rats and were labeled with Resovist(11.2 μg/mL and 5 × 105 cells/mL).A total of 15 adult,Sprague Dawley rats were randomly assigned to model(n = 9) and control(n = 6) groups.All rats were utilized to establish models of middle cerebral artery occlusion.Rats in the model group were subjected to Resovist-labeled NSCs transplantation by injection of cell suspension into both ventricles(5 μL/ventricle).Rats in the control group were treated with an equal volume of physiological saline.MAIN OUTCOME MEASURES:Immunocytochemistry,transmission electron microscopy,and Prussian blue staining were employed to observe whether cells phagocytized iron particles.In addition,3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to measure viability and differentiation of NSCs labeled by various concentrations of Resovist.MRI was used to trace survival and migration of Resovist-labeled NSCs.RESULTS:Following Resovist and NSCs co-incubation,Prussian blue staining revealed iron particles in cells.In addition,staining was observed in daughter cells following cell division under transmission electron microscopy.A significant difference in viability and differentiation of NSCs in vitro labeled by various Resovist concentrations(2.8-11.2 μg/mL) was not detected(P > 0.05).Resovist(> 22.4 μg/mL) decreased cell viability and differentiation(P < 0.05).In vivo MRI of Resovist-labeled NSCs(11.2 μg/mL) revealed low signals.However,cells migrated towards the ischemic focus over time.CONCLUSION:Resovist,a magnetic probe,successfully labeled NSCs.MRI was successfully used to trace magnetic-labeled NSCs in vivo and allowed observation of cell survival and migration following transplantation.展开更多
Objective: Little is known about the cardiac contractility recovery after exercise. The objective of the study was to explore a method to evaluate the extent and speed of cardiac function up-regulation during exercise...Objective: Little is known about the cardiac contractility recovery after exercise. The objective of the study was to explore a method to evaluate the extent and speed of cardiac function up-regulation during exercise and the recovery course of cardiac contractility and heart rate after exercise. Methods: Ten student athletes and ten student non-athlete voluntarily participated in this controlled study. Three indicators were selected: 1) amplitude ratio of the first to second heart sound (S1/S2);2) heart rate (HR);3) power output (W). Phonocardiogram exercise test (PCGET) was adopted. A four-stage workload increment protocol was used. Phonocardiograms were recorded in the sitting position at rest and immediately after each test stage. The time taken for completing the workloads 1750 J, 3500 J, 5250 J, and 7000 J was recorded, respectively. During recovery heart sound signals were recorded immediately after exercise, and at 1, 5, 10, 15, 20, 25, and 30 minutes after exercise. S1/S2, HR, and W were calculated from the measured data. Cardiac function change trend graphs were constructed. Results: During exercise, HR and S1/S2 ratio increased with the increase in workload from 1750 J to 7000 J;the level and speed of increase in power output and S1/S2 ratio of the athletes were higher than the general students;power done by the general students decreased earlier than the athletes. During recovery course, the recovery course of the general students was slower than the athletes. Conclusion: This method for evaluating cardiac function up-regulation and recovery course is safe, easy, reliable, and effective, which is beneficial for selecting athletes, training, and matchmaking.展开更多
Defect-induced charge carrier recombination at the interfaces between perovskite and adjacent charge transport layers restricts further improvements in the device performance of perovskite solar cells(PSCs).Defect pas...Defect-induced charge carrier recombination at the interfaces between perovskite and adjacent charge transport layers restricts further improvements in the device performance of perovskite solar cells(PSCs).Defect passivation at these interfaces can reduce trap states and inhibit the induced nonradiative recombination.Herein,we report a double-sided interfacial passivation via simply evaporating potassium chloride(DIP-KCl)at both the hole transport layer(HTL)/perovskite and perovskite/electron transport layer(ETL)interfaces in inverted planar PSCs.We demonstrate that the bottom KCl layer at the HTL/perovskite interface not only reduces the interfacial defects and improves the interfacial contact,but also leads to increased perovskite crystallinity,while the top KCl layer at the perovskite/ETL interface efficiently passivates the perovskite top surface defects and facilitates electron extraction at this interface.Thus,suppressed nonradiative recombination and faster charge extraction at both interfaces close to the perovskite layer can be achieved by using our DIP-KCl strategy.As a result,inverted PSCs based on DIP-KCl present an increased efficiency from 17.1% to 19.2% and enhanced stability,retaining over 90% of their initial efficiency after aging at maximum power point tracking for 1000 h.This work provides a simple and efficient way for defect passivation to further increase the efficiency and stability of PSCs.展开更多
Background: It is difficult to observe the phenomena of cardiac fatigue under a low or moderate workload test, and little was reported about cardiac fatigue under a heavy workload test because of the potential risk (s...Background: It is difficult to observe the phenomena of cardiac fatigue under a low or moderate workload test, and little was reported about cardiac fatigue under a heavy workload test because of the potential risk (sudden death) of prolonged strenuous exercise. Animal experiments would be helpful to resolve this problem. The objective of this study was to obtain baseline data of two new indicators of cardiac reserve in rats, rabbits, and dogs. Methods: Ten New Zealand White rabbits (1. 5 to 2 kg, 4 females), 10 male Wistar rats (2 months old), and 10 Golden Retriever dogs (40 days old, 5 females) were included in this study. Phonocardiogram of each animal was recorded. The basic points concerning heart sound quantitative analysis were: 1) measuring the duration and the amplitude of relevant heart sound components;2) calculating and analyzing relevant indicators based on the data obtained from the above measurements, including the ratio of diastolic to systolic duration (D/S) and the ratio of the amplitude of the first heart sound to the amplitude of the second heart sound (S1/S2). Results: The baseline data of D/S ratio and S1/S2 ratio in rats, rabbits, and dogs were obtained. The swimming time to exhaustion for rabbits was several to a dozen minutes, and for rats, several hours. Conclusion: D/S ratio has an important biological implication, which is a safe and easy indicator for evaluating the cardiac health status of both animals and humans.展开更多
文摘Arson presents a challenging crime scene for fire investigators worldwide. Key to the investigation of suspected arson cases is the analysis of fire debris for the presence of accelerants or ignitable liquids. This study has investigated the application and method development of vapor phase mid-Infrared (mid-IR) spectroscopy using a field portable quantum cascade laser (QCL) based system for the detection and identification of accelerant residues such as gasoline, diesel, and ethanol in fire debris. A searchable spectral library of various ignitable fluids and fuel components measured in the vapor phase was constructed that allowed for real-time identification of accelerants present in samples using software developed in-house. Measurement of vapors collected from paper material that had been doused with an accelerant followed by controlled burning and then extinguished with water showed that positive identification could be achieved for gasoline, diesel, and ethanol. This vapor phase mid-IR QCL method is rapid, easy to use, and has the sensitivity and discrimination capability that make it well suited for non-destructive crime scene sample analysis. Sampling and measurement can be performed in minutes with this 7.5 kg instrument. This vibrational spectroscopic method required no time-consuming sample pretreatment or complicated solvent extraction procedure. The results of this initial feasibility study demonstrate that this portable fire debris analyzer would greatly benefit arson investigators performing analysis on-site.
文摘Background: Since the greater part of coronary blood flow takes place during the diastolic phase of each cardiac cycle, a time indicator of myocardial perfusion reserve, the ratio of diastolic to systolic duration (D/S ratio), was presented. The objective of this study was to evaluate the accuracy and precision, the biological implication, and the applications of D/S ratio. Methods: Multi-center pragmatic studies evaluating the time indicator of cardiac perfusion reserve were performed. Related experiments, clinical trials, and surveys were conducted at 5 centers. Results: The results showed that the measurement of D/S ratio is both accurate and precise;the mean values of D/S of all of the 3 species studied (human, rabbit, and rat) were greater than 1. These application studies on D/S ratio showed that a close negative correlation existed between D/S ratio and New York Heart Association Functional Classification (NYHA FC) (r = –0.659, p pregnant women with pre-eclampsia and either normal pregnant women or non-pregnant women were significant (p Conclusions: D/S ratio has important biological implication, which is a safe, easy, reliable, and effective indicator, can be used to evaluate fitness levels, served as a pathophysiological marker for screening of cardiovascular disease (CVD), for predicting risk of cardiac events, and for evaluating the severity and prognosis of CVD.
基金the Scientific Research Program of Health Department in Heilongjiang Province,No.2007-331the Doctoral Foundation of the Second Affiliated Hospital of Harbin Medical University,No.BS2006-29
文摘BACKGROUND:Resovist,a superparamagnetic iron oxide,can be used to label neural stem cells(NSCs).Magnetic resonance tracking of superparamagnetic iron oxide-labeled NSCs is a non-invasive technique to track transplanted NSCs following focal cerebral ischemia.OBJECTIVE:To observe survival and migration of transplanted NSCs in a rat model of focal ischemia/reperfusion using magnetic resonance imaging(MRI).DESIGN,TIME AND SETTING:An in vitro,in vivo,tracking study was performed at the Basic Laboratory of Harbin Medical University and the Room of MRI,Second Affiliated Hospital of Harbin Medical University,China from December 2006 to December 2009.MATERIALS:Resovist(Schering,Germany) and Achieva 1.5TMR imaging system(Philips,Amsterdam,the Netherlands) were utilized in the present study.METHODS:NSCs were harvested from brain tissues of neonatal Sprague Dawley rats and were labeled with Resovist(11.2 μg/mL and 5 × 105 cells/mL).A total of 15 adult,Sprague Dawley rats were randomly assigned to model(n = 9) and control(n = 6) groups.All rats were utilized to establish models of middle cerebral artery occlusion.Rats in the model group were subjected to Resovist-labeled NSCs transplantation by injection of cell suspension into both ventricles(5 μL/ventricle).Rats in the control group were treated with an equal volume of physiological saline.MAIN OUTCOME MEASURES:Immunocytochemistry,transmission electron microscopy,and Prussian blue staining were employed to observe whether cells phagocytized iron particles.In addition,3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to measure viability and differentiation of NSCs labeled by various concentrations of Resovist.MRI was used to trace survival and migration of Resovist-labeled NSCs.RESULTS:Following Resovist and NSCs co-incubation,Prussian blue staining revealed iron particles in cells.In addition,staining was observed in daughter cells following cell division under transmission electron microscopy.A significant difference in viability and differentiation of NSCs in vitro labeled by various Resovist concentrations(2.8-11.2 μg/mL) was not detected(P > 0.05).Resovist(> 22.4 μg/mL) decreased cell viability and differentiation(P < 0.05).In vivo MRI of Resovist-labeled NSCs(11.2 μg/mL) revealed low signals.However,cells migrated towards the ischemic focus over time.CONCLUSION:Resovist,a magnetic probe,successfully labeled NSCs.MRI was successfully used to trace magnetic-labeled NSCs in vivo and allowed observation of cell survival and migration following transplantation.
文摘Objective: Little is known about the cardiac contractility recovery after exercise. The objective of the study was to explore a method to evaluate the extent and speed of cardiac function up-regulation during exercise and the recovery course of cardiac contractility and heart rate after exercise. Methods: Ten student athletes and ten student non-athlete voluntarily participated in this controlled study. Three indicators were selected: 1) amplitude ratio of the first to second heart sound (S1/S2);2) heart rate (HR);3) power output (W). Phonocardiogram exercise test (PCGET) was adopted. A four-stage workload increment protocol was used. Phonocardiograms were recorded in the sitting position at rest and immediately after each test stage. The time taken for completing the workloads 1750 J, 3500 J, 5250 J, and 7000 J was recorded, respectively. During recovery heart sound signals were recorded immediately after exercise, and at 1, 5, 10, 15, 20, 25, and 30 minutes after exercise. S1/S2, HR, and W were calculated from the measured data. Cardiac function change trend graphs were constructed. Results: During exercise, HR and S1/S2 ratio increased with the increase in workload from 1750 J to 7000 J;the level and speed of increase in power output and S1/S2 ratio of the athletes were higher than the general students;power done by the general students decreased earlier than the athletes. During recovery course, the recovery course of the general students was slower than the athletes. Conclusion: This method for evaluating cardiac function up-regulation and recovery course is safe, easy, reliable, and effective, which is beneficial for selecting athletes, training, and matchmaking.
基金financially supported by the National Natural Science Foundation of China,China(51672094,51861145404,51822203,and 11627801)the National Key Research and Development Program of China,China(2016YFA0201001)+4 种基金the China Postdoctoral Science Foundation(2016M602286)the Fundamental Research Funds for the Central Universities,China(2016JCTD111,2018RCPY003,2020kfy XJJS008)the Shenzhen Science and Technology Innovation Committee,China(JCYJ20170307165905513,JCYJ20180507182257563)the Natural Science Foundation of Guangdong Province,China(2017A030313342)the Outstanding Young Talent Research Fund of Zhengzhou University,China。
文摘Defect-induced charge carrier recombination at the interfaces between perovskite and adjacent charge transport layers restricts further improvements in the device performance of perovskite solar cells(PSCs).Defect passivation at these interfaces can reduce trap states and inhibit the induced nonradiative recombination.Herein,we report a double-sided interfacial passivation via simply evaporating potassium chloride(DIP-KCl)at both the hole transport layer(HTL)/perovskite and perovskite/electron transport layer(ETL)interfaces in inverted planar PSCs.We demonstrate that the bottom KCl layer at the HTL/perovskite interface not only reduces the interfacial defects and improves the interfacial contact,but also leads to increased perovskite crystallinity,while the top KCl layer at the perovskite/ETL interface efficiently passivates the perovskite top surface defects and facilitates electron extraction at this interface.Thus,suppressed nonradiative recombination and faster charge extraction at both interfaces close to the perovskite layer can be achieved by using our DIP-KCl strategy.As a result,inverted PSCs based on DIP-KCl present an increased efficiency from 17.1% to 19.2% and enhanced stability,retaining over 90% of their initial efficiency after aging at maximum power point tracking for 1000 h.This work provides a simple and efficient way for defect passivation to further increase the efficiency and stability of PSCs.
文摘Background: It is difficult to observe the phenomena of cardiac fatigue under a low or moderate workload test, and little was reported about cardiac fatigue under a heavy workload test because of the potential risk (sudden death) of prolonged strenuous exercise. Animal experiments would be helpful to resolve this problem. The objective of this study was to obtain baseline data of two new indicators of cardiac reserve in rats, rabbits, and dogs. Methods: Ten New Zealand White rabbits (1. 5 to 2 kg, 4 females), 10 male Wistar rats (2 months old), and 10 Golden Retriever dogs (40 days old, 5 females) were included in this study. Phonocardiogram of each animal was recorded. The basic points concerning heart sound quantitative analysis were: 1) measuring the duration and the amplitude of relevant heart sound components;2) calculating and analyzing relevant indicators based on the data obtained from the above measurements, including the ratio of diastolic to systolic duration (D/S) and the ratio of the amplitude of the first heart sound to the amplitude of the second heart sound (S1/S2). Results: The baseline data of D/S ratio and S1/S2 ratio in rats, rabbits, and dogs were obtained. The swimming time to exhaustion for rabbits was several to a dozen minutes, and for rats, several hours. Conclusion: D/S ratio has an important biological implication, which is a safe and easy indicator for evaluating the cardiac health status of both animals and humans.
基金We gratefully thank the National Natural Science Foundation of China （Grant Nos. 21276128 and 21006052） and the Basic Research Program of Jiangsu Province of China （BK20141398） for the financial supports.
