Crimped ribbon flame arresters are important safety devices in the chemical industry, especially for the danger- ous situations. Although proper design of arresters by the numerical simulation method is promising, its...Crimped ribbon flame arresters are important safety devices in the chemical industry, especially for the danger- ous situations. Although proper design of arresters by the numerical simulation method is promising, its reliabil- ity and accuracy are dependent upon the mathematical model. In this work, an integrated mathematical model for the microchannel in the crimped ribbon flame attesters was set up; the fluid flow behavior and the sensitiv- ities of four chemical kinetics mechanisms of propane-air on the accuracy were analysed. It is shown that turbu- lence is predominant in the microchannel of the crimped ribbon flame arresters under the defiagration and detonation conditions, and a new quenching criterion for the numerical simulation is proposed. The kinetics mechanism of Mansouri et al. among the four ones is the most accurate due to the best agreement of the pre- dicted outlet temperature at the experimental flameproof velocity with the autoignition temperature of propane-air. The species mass fraction profiles and the temperature distribution, which are too difficult to mea- sure due to the tiny dimension of the microchannel in experiments, are captured. The fundamental insights into chemical reactions and heat loss are well portrayed. It can be concluded that the integrated mathematical model established in this work can be used as a reliable tool for modeling, selecting and designing such type of crimped ribbon flame attesters with the propane-air medium in the future.展开更多
In this paper, controlling chaos when chaotic ferroresonant oscillations occur in a voltage transformer with nonlin- ear core loss model is performed. The effect of a parallel metal oxide surge arrester on the ferrore...In this paper, controlling chaos when chaotic ferroresonant oscillations occur in a voltage transformer with nonlin- ear core loss model is performed. The effect of a parallel metal oxide surge arrester on the ferroresonance oscillations of voltage transformers is studied. The metal oxide arrester （MOA） is found to be effective in reducing ferroresonance chaotic oscillations. Also the multiple scales method is used to analyze the chaotic behavior and different types of fixed points in ferroresonance of voltage transformers considering core loss. This phenomenon has nonlinear chaotic dynamics and includes sub-harmonic, quasi-periodic, and also chaotic oscillations. In this paper, the chaotic behavior and various ferroresonant oscillation modes of the voltage transformer is studied. This phenomenon consists of different types of bifur- cations such as period doubling bifurcation （PDB）, saddle node bifurcation （SNB）, Hopf bifurcation （HB）, and chaos. The dynamic analysis of ferroresonant circuit is based on bifurcation theory. The bifurcation and phase plane diagrams are il- lustrated using a continuous method and linear and nonlinear models of core loss. To analyze ferroresonance phenomenon, the Lyapunov exponents are calculated via the multiple scales method to obtain Feigenbaum numbers. The bifurcation diagrams illustrate the variation of the control parameter. Therefore, the chaos is created and increased in the system.展开更多
Rogowski coils(RCs)are widely used to measure power or high frequency currents based on their design.In this paper,two types of RCs that are circular(traditional)and cylindrical shapes wound using wire covered by varn...Rogowski coils(RCs)are widely used to measure power or high frequency currents based on their design.In this paper,two types of RCs that are circular(traditional)and cylindrical shapes wound using wire covered by varnish are constructed.This construction is carried out to be suitable for monitoring the discharge current of the surge arrester installed in the distribution system.Concerning high frequency RC modeling for both types considering transfer function is introduced.Self-integrating for both types is attained.Therefore,the experimental tests using function generator for both coils are carried out to identify the parameters of the transfer function representing the introduced model.The measured signals for current and induced voltages are denoised for the parameter identification process.The denoised process is achieved using the MATLAB code‘wdenoise’while the parameters are estimated using the system identification toolbox.Verification of the proposed model is achieved using experimental results for the two coils.The sensitivity of the two coils is investigated based on the induced output voltage.The application concerning the two coils for monitoring the discharge current of the surge arrester is done.The results confirm the accuracy of the introduced RC model,as well as the performance of the cylindrical shape,is better than the traditional one.The simulation is carried out using MATLAB and ATPDraw programs.展开更多
Zinc Oxide (ZnO) surge arresters (SAs) experience thermal runaway when the temperature exceeds the acceptable limit. This phenomenon is associated with the increase in resistive leakage current due to degradation. Thi...Zinc Oxide (ZnO) surge arresters (SAs) experience thermal runaway when the temperature exceeds the acceptable limit. This phenomenon is associated with the increase in resistive leakage current due to degradation. This paper presents the electrical performance of ZnO SAs in 22 kV distribution systems using thermal image camera under the power frequency AC operating voltages. When ZnO surge arresters are installation takes a long time in distribution system over more than 5 years. For the experimental study, as ZnO installation takes a long time over 6 years the leakage current is 63.9 mA, temperature differences were measured over a period of time over 14 degree Celsius. This data will be useful as a guideline for solving problems and reducing power loss from leakage current. Moreover, it will be useful in predicting lifetime of ZnO SAs.展开更多
Shanghai Electric Porcelain Works (SEPW), a subsidiary enterprise of the SEC (Group), is specialized in manufacturing highvoltage surge arresters and fuses as main products, as well as some high-voltage insulators, wa...Shanghai Electric Porcelain Works (SEPW), a subsidiary enterprise of the SEC (Group), is specialized in manufacturing highvoltage surge arresters and fuses as main products, as well as some high-voltage insulators, wall bushings and disconnecting switches for power transmission & distribution systems. In fact, SEPW is展开更多
Due to important consideration of protection against lightning surge on electrical, electronic and telecommunication equipment, it was necessary to carry out a special study to look at the performance of protective de...Due to important consideration of protection against lightning surge on electrical, electronic and telecommunication equipment, it was necessary to carry out a special study to look at the performance of protective devices. The study was testing performance of arresters on low voltage system. The activity was testing of arresters using steady state and impulse voltages. The arresters consisted of gas tube, zener diode, varistor and spark gap arresters, then it was made a cascade circuit between the varistor and spark gap arresters with a decoupling element. The decoupling elements were used air, iron and ferrite. The test yielded data of current and voltage on the tables and oscilloscope waveforms. The arresters had cut voltages early different from each other, namely the gas tube, zener diode, spark gap and varistor arresters were at the voltages of 500 V, 250 V, 1,000 V and 565 V respectively. The iron core decoupling element cascade circuit had the least oscillation among remaining cores.展开更多
The resistance characteristics of a corrugated flame arrester in hydrogen explosions were investigated using a visual explosion-retardant system.By varying the structural parameters of the corrugated flame-retardant s...The resistance characteristics of a corrugated flame arrester in hydrogen explosions were investigated using a visual explosion-retardant system.By varying the structural parameters of the corrugated flame-retardant system and the concentration of hydrogen,the flame resistance characteristics and the mechanisms affecting hydrogen explosions were summarized.The results indicate that there was a clear correlation between the flame propagation and pressure rise during explosion resistance.When the flame resistance failed,a significant enhancement effect was observed at the backend of the flame-retardant system.Additionally,a noticeable oscillation occurred in the initial stage of flame propagation due to the obstruction caused by the flame-retardant system.The thickness and porosity of the flame-retardant system,along with the hydrogen concentration,influenced the intensities of shock waves and flames entering the narrow channel,as well as the physical and chemical effects during internal propagation,thereby affecting the overall flame resistance.展开更多
Cardiac arrest can lead to severe neurological impairment as a result of inflammation,mitochondrial dysfunction,and post-cardiopulmonary resuscitation neurological damage.Hypoxic preconditioning has been shown to impr...Cardiac arrest can lead to severe neurological impairment as a result of inflammation,mitochondrial dysfunction,and post-cardiopulmonary resuscitation neurological damage.Hypoxic preconditioning has been shown to improve migration and survival of bone marrow–derived mesenchymal stem cells and reduce pyroptosis after cardiac arrest,but the specific mechanisms by which hypoxia-preconditioned bone marrow–derived mesenchymal stem cells protect against brain injury after cardiac arrest are unknown.To this end,we established an in vitro co-culture model of bone marrow–derived mesenchymal stem cells and oxygen–glucose deprived primary neurons and found that hypoxic preconditioning enhanced the protective effect of bone marrow stromal stem cells against neuronal pyroptosis,possibly through inhibition of the MAPK and nuclear factor κB pathways.Subsequently,we transplanted hypoxia-preconditioned bone marrow–derived mesenchymal stem cells into the lateral ventricle after the return of spontaneous circulation in an 8-minute cardiac arrest rat model induced by asphyxia.The results showed that hypoxia-preconditioned bone marrow–derived mesenchymal stem cells significantly reduced cardiac arrest–induced neuronal pyroptosis,oxidative stress,and mitochondrial damage,whereas knockdown of the liver isoform of phosphofructokinase in bone marrow–derived mesenchymal stem cells inhibited these effects.To conclude,hypoxia-preconditioned bone marrow–derived mesenchymal stem cells offer a promising therapeutic approach for neuronal injury following cardiac arrest,and their beneficial effects are potentially associated with increased expression of the liver isoform of phosphofructokinase following hypoxic preconditioning.展开更多
The surge arrester with excellent protection characteristics would decrease the overvoltage level ap- plied on the power apparatus to reduce their insulation levels and manufacturing bottleneck. The arrester for the 1...The surge arrester with excellent protection characteristics would decrease the overvoltage level ap- plied on the power apparatus to reduce their insulation levels and manufacturing bottleneck. The arrester for the 1000-kV ultra-high voltage ac power transmission system is designed as tank-type structure. The field-circuit combination numerical method combining the three-dimensional finite element method with circuit is proposed to analyze the potential distribution of GIS arrester. By comparing several design schemes, the most effective method to improve the potential distribution along the varistor column is to increase the voltage gradient of the ZnO varistor. Synthesizing several influential factors, the suitable voltage gradient of ZnO varistor should be controlled to 435 V/mm, and the resulted nonuniform degree of the potential distribution along the varistor column inside the GIS arrester would be controlled smaller than 10%. The result in this paper provides the fundamental technical index for the study of the high voltage gradient ZnO varistors.展开更多
An experimental system that consisted of gas mixing equipment, a sensor detection system, a data acquisition device, and an electric spark ignition device was set up to investigate fuel/air deflagration flame propagat...An experimental system that consisted of gas mixing equipment, a sensor detection system, a data acquisition device, and an electric spark ignition device was set up to investigate fuel/air deflagration flame propagation and quenching processes through a crimped-ribbon flame arrester in an enclosed horizontal pipe. Deflagration suppression experiments showed that when the concentration of flammable gas was close to the stoichiometric ratio, the evolution processes of explosion pressure for the propane-air and ethylene-air premixed gases in the pipe diameter （DN32-DN400） were similar and could be divided into four stages： isobaric combustion, slow pressure rise, quick pressure rise, and pressure oscillation. However, the explosion duration of the hydrogen-air premixed gas was relatively short, and the peak explosion pressure was high. The pressure rose quickly after the isobaric combustion stage. Therefore, the process can be divided into three stages in the pipe diameter （DN15-DN150）. Deflagration speed results indicated that the propane-air flame speed initially increased and eventually decreased along with increases in the pipe diameter （DN32-DN400）; however, the ethylene-air flame speed gradually increased with the increase of the pipe diameter （DNS0-DN400）. No notable pattern of change in the hydrogen-air flame speed was observed in the pipe diameter （DN15-DN150）. The maximum propane-air flame speed occurred at 5% concentration. The maximum flame speed for ethylene-air and hydrogen-air happened when the mixture was close to stoichiometric ratio. Under the conditions of the same size of experimental tube configuration and the same ignition distance but different pipe lengths, or the same pipe length but different ignition distances, experimental results showed that the flame arrester successfully stopped the flames at high flame speed and low explosion pressure, but failed at low flame speed and high explosion pressure.展开更多
Severe fever with thrombocytopenia syndrome(SFTS)is a novel emerging acute infectious disease caused by severe fever with thrombocytopenia syndrome virus(SFTSV),characterized by high fever and thrombocytopenia.It has ...Severe fever with thrombocytopenia syndrome(SFTS)is a novel emerging acute infectious disease caused by severe fever with thrombocytopenia syndrome virus(SFTSV),characterized by high fever and thrombocytopenia.It has been proved that traditional Chinese medicine(TCM)has displayed definite therapeutic effects on viral hemorrhagic fever,indicating its potential to treat SFTS.In this study,SFTS-relative key targets were predicted via gene ontology(GO)analysis and kyoto encyclopedia of genes and genomes(KEGG)enrichment analysis.Molecular docking was then used to select stable binders.Molecules matched TCMs were identified,and a new prescription,Qingqi Guxue decoction(QQGX),was formulated to clear heat and nourish blood,with a resulting drug composition network.We explored the optimal drug proportion for QQGX.Through an in-depth study of molecular mechanisms,we found that QQGX induces S phase arrest by promoting the degradation of cyclin A2(CCNA2)and cyclin-dependent kinase 2(CDK2),thereby inhibiting SFTSV replication.Finally,we verified the effectiveness and safety of QQGX based on the mouse liver bile duct organoid model infected with SFTSV.In summary,our study prepared a TCM decoction using the method of network pharmacology.This decoction has a significant inhibitory effect on the replication of SFTSV and provides a new treatment strategy for hemorrhagic fever with TCM.展开更多
Global brain ischemia and neurological deficit are consequences of cardiac arrest that lead to high mortality.Despite advancements in resuscitation science,our limited understanding of the cellular and molecular mecha...Global brain ischemia and neurological deficit are consequences of cardiac arrest that lead to high mortality.Despite advancements in resuscitation science,our limited understanding of the cellular and molecular mechanisms underlying post-cardiac arrest brain injury have hindered the development of effective neuroprotective strategies.Previous studies primarily focused on neuronal death,potentially overlooking the contributions of non-neuronal cells and intercellular communication to the pathophysiology of cardiac arrest-induced brain injury.To address these gaps,we hypothesized that single-cell transcriptomic analysis could uncover previously unidentified cellular subpopulations,altered cell communication networks,and novel molecular mechanisms involved in post-cardiac arrest brain injury.In this study,we performed a single-cell transcriptomic analysis of the hippocampus from pigs with ventricular fibrillation-induced cardiac arrest at 6 and 24 hours following the return of spontaneous circulation,and from sham control pigs.Sequencing results revealed changes in the proportions of different cell types,suggesting post-arrest disruption in the blood-brain barrier and infiltration of neutrophils.These results were validated through western blotting,quantitative reverse transcription-polymerase chain reaction,and immunofluorescence staining.We also identified and validated a unique subcluster of activated microglia with high expression of S100A8,which increased over time following cardiac arrest.This subcluster simultaneously exhibited significant M1/M2 polarization and expressed key functional genes related to chemokines and interleukins.Additionally,we revealed the post-cardiac arrest dysfunction of oligodendrocytes and the differentiation of oligodendrocyte precursor cells into oligodendrocytes.Cell communication analysis identified enhanced post-cardiac arrest communication between neutrophils and microglia that was mediated by neutrophil-derived resistin,driving pro-inflammatory microglial polarization.Our findings provide a comprehensive single-cell map of the post-cardiac arrest hippocampus,offering potential novel targets for neuroprotection and repair following cardiac arrest.展开更多
Brain plasticity-A universal tool with many variations:The study of brain plasticity has been gaining interest since almost a century and has now reached a huge amount of information(>80,000 results in PubMed).Over...Brain plasticity-A universal tool with many variations:The study of brain plasticity has been gaining interest since almost a century and has now reached a huge amount of information(>80,000 results in PubMed).Overall,different types of plasticity,including stem cell-driven genesis of new neurons(adult neurogenesis),cells in arrested maturation(dormant neurons),neuro-glial and synaptic plasticity,can coexist and contribute to grant plastic changes in the brain,from a cellular to system level(Benedetti and Couillard-Despres,2022;Bonfanti et al.,2023).展开更多
BACKGROUND Acute pancreatitis in pregnancy is a rare but serious condition that can lead to high maternal mortality and fetal loss.Instances of pregnancy complicated by severe acute pancreatitis,particularly with subs...BACKGROUND Acute pancreatitis in pregnancy is a rare but serious condition that can lead to high maternal mortality and fetal loss.Instances of pregnancy complicated by severe acute pancreatitis,particularly with subsequent respiratory and cardiac arrest,are rarely reported.CASE SUMMARY We present the case of a 35-year-old woman,at 36+5 weeks of gestation,who presented with paroxysmal epigastric pain accompanied by low back pain,nausea,and vomiting.According to the clinical symptoms,B-ultrasound imaging and biochemical indicators,the patient was diagnosed with acute pancreatitis and initially managed conservatively.However,3 hours after admission,the patient experienced respiratory and cardiac arrest,and the fetus died.In this case,the adverse outcomes occurred due to the lack of aggressive fluid resuscitation and an active surgical intervention.CONCLUSION Implementing aggressive fluid resuscitation to sustain tissue perfusion,alongside the proactive evaluation of pharmacological agents that suppress gastric acid secretion and inhibit pancreatic enzyme activity,may be beneficial in mitigating the risk of a severely adverse prognosis.Effective management of acute pancreatitis during pregnancy requires careful timing of surgical intervention,a thorough evaluation of the risks and benefits regarding the continuation or termination of pregnancy,and a focus on safeguarding both maternal and fetal health.展开更多
Cardiac arrest(CA)is a critical condition in the field of cardiovascular medicine.Despite successful resuscitation,patients continue to have a high mortality rate,largely due to post CA syndrome(PCAS).However,the inju...Cardiac arrest(CA)is a critical condition in the field of cardiovascular medicine.Despite successful resuscitation,patients continue to have a high mortality rate,largely due to post CA syndrome(PCAS).However,the injury and pathophysiological mechanisms underlying PCAS remain unclear.Experimental animal models are valuable tools for exploring the etiology,pathogenesis,and potential interventions for CA and PCAS.Current CA animal models include electrical induction of ventricular fibrillation(VF),myocardial infarction,high potassium,asphyxia,and hemorrhagic shock.Although these models do not fully replicate the complexity of clinical CA,the mechanistic insights they provide remain highly relevant,including post-CA brain injury(PCABI),post-CA myocardial dysfunction(PAMD),systemic ischaemia/reperfusion injury(IRI),and the persistent precipitating pathology.Summarizing the methods of establishing CA models,the challenges encountered in the modeling process,and the mechanisms of PCAS can provide a foundation for developing standardized CA modeling protocols.展开更多
BACKGROUND Cardiac arrest caused by acute pulmonary embolism(PE)is the most serious clinical circumstance,necessitating rapid identification,immediate cardiopulmonary resuscitation(CPR),and systemic thrombolytic thera...BACKGROUND Cardiac arrest caused by acute pulmonary embolism(PE)is the most serious clinical circumstance,necessitating rapid identification,immediate cardiopulmonary resuscitation(CPR),and systemic thrombolytic therapy.Extracorporeal CPR(ECPR)is typically employed as a rescue therapy for selected patients when conventional CPR is failing in settings where it can be implemented.CASE SUMMARY We present a case of a 69-year-old male who experienced a prolonged cardiac arrest in an ambulance with pulseless electrical activity.Upon arrival at the emergency department with ongoing manual chest compressions,bedside pointof-care ultrasound revealed an enlarged right ventricle without contractility.Acute PE was suspected as the cause of cardiac arrest,and intravenous thrombolytic therapy with 50 mg tissue plasminogen activator was administered during mechanical chest compressions.Despite 31 minutes of CPR,return of spontaneous circulation was not achieved until 8 minutes after initiation of Veno-arterial extracorporeal membrane oxygenation(ECMO)support.Under ECMO support,the hemodynamic status and myocardial contractility significantly improved.However,the patient ultimately did not survive due to intracerebral hemorrhagic complications,leading to death a few days later in the hospital.CONCLUSION This case illustrates the potential of combining systemic thrombolysis with ECPR for refractory cardiac arrest caused by acute PE,but it also highlights the increased risk of significant bleeding complications,including fatal intracranial hemorrhage.展开更多
Cardiac arrest(CA)is considered a state of clinical death in which the heart suddenly loses its ability to effectively expel blood,resulting in circulatory and respiratory arrest.CA is often catastrophic for patients,...Cardiac arrest(CA)is considered a state of clinical death in which the heart suddenly loses its ability to effectively expel blood,resulting in circulatory and respiratory arrest.CA is often catastrophic for patients,as it can cause serious long-term cardiovascular and cerebrovascular complications that affect their quality of life[1].Survey data indicate that the overall incidence rate of intraoperative CA in patients undergoing thoracic surgery in China is currently 0.138%[2].This rate is expected to increase because of the increasing proportion of older individuals(age>60 years)in the population,as well as the increasing pulmonary surgery rates.However,the incidence rate during the perianesthetic period in older patients undergoing thoracic surgery has not yet been comprehensively reported.展开更多
The amplitude of switching overvoltages is a key factor for designing the insulation of UHV equipment. The effect of different arresters needs to be studied, since installing arresters is an important way to suppress ...The amplitude of switching overvoltages is a key factor for designing the insulation of UHV equipment. The effect of different arresters needs to be studied, since installing arresters is an important way to suppress switching overvoltages in UHV transmission lines. Switching overvoltages on the 1000 kV Huainan-Huxi double-circuit transmission line were simulated for different operating modes and different arrester designs using the electromagnetic transient program PSCAD/EMTDC. With parallel resistors, the switching overvoltages are less than 1.70 p.u. （1.0 p.u.=1100×√ 2 /√3 kV）. If the arrestors are better, the switching overvoltages can be reduced even lower to 1.55 p.u. Without parallel resistors, the arresters can reduce three-phase energizing overvoltages to 1.70 p.u, while the single-phase reclosing overvoltages still exceed the limit. The results show that the parallel resistors cannot be eliminated if the arresters are only installed at each end of the transmission line. Also, better quality arresters significantly lower the switching overvoltages.展开更多
BACKGROUND:Post-cardiac arrest syndrome(PCAS) significantly contributes to mortality after initially successful cardiopulmonary resuscitation(CPR) in cardiac arrest(CA) patients.Effective cardiocerebral protection is ...BACKGROUND:Post-cardiac arrest syndrome(PCAS) significantly contributes to mortality after initially successful cardiopulmonary resuscitation(CPR) in cardiac arrest(CA) patients.Effective cardiocerebral protection is essential for improving post-resuscitation survival.This study investigated the mechanisms and common targets of myocardial dysfunction and brain injury after resuscitation.METHODS:The male Sprague-Dawley rats(10–12 weeks old,400–500 g) were divided into two groups:the control group(n=6),which received sham surgery,and the CA/CPR group(n=10),which received ventricular fibrillation(VF) followed by CPR.After 24 h,brain and heart tissues were collected for analysis.The sequencing was used to identify differentially expressed genes(DEGs) between control and CA/CPR rats.RESULTS:At 24 h after resuscitation,CA/CPR rats presented 217 DEGs in the hippocampus and 80 DEGs in the left ventricle(LV) compared to the control group.In the hippocampus,the most notable biological process was the positive regulation of tumor necrosis factor production,with key pathways related to inflammation and the immune response.In the LV,the Gene Ontology(GO)enrichment analysis revealed that gene alterations were primarily associated with amyloid-beta clearance,a pathway that was also relevant in the brain.Eleven common targets were identified in the DEGs of both heart and brain tissues.The reverse transcription-polymerase chain reaction(RTPCR) validation revealed significant differences in the mRNA expression of Timp1,Apln,Ccl7,and Lgals3 in both LV and hippocampus.CONCLUSION:This study identified possible key genes and underlying mechanisms involved in PCAS.The differential genes Timp1,Apln,Ccl7,and Lgals3 might serve as common biomarkers for myocardial and neurological injury following resuscitation.展开更多
Modern cardiopulmonary resuscitation(CPR)has been established for more than 60 years;however,its success rate remains low.Currently,the global incidence of out-of-hospital cardiac arrest(OHCA)is rising,ranging from 52...Modern cardiopulmonary resuscitation(CPR)has been established for more than 60 years;however,its success rate remains low.Currently,the global incidence of out-of-hospital cardiac arrest(OHCA)is rising,ranging from 52.5 to 97.1 per 100,000 population.[1,2]Survival-to-discharge rates for OHCA and in-hospital cardiac arrest(IHCA)are not satisfactory,with ranges of 1.2%-9.9%and 9.1%-19.1%,respectively.展开更多
基金Supported by the National Key Research and Development Program of China(2016YFB0301701)the National Natural Science Foundation of China(21706268+4 种基金9143411421376254)the Postdoctoral Science Foundation of Qingdao Municipal Government(Y7330419DM)the Instrument Developing Project of the Chinese Academy of Sciences(YZ201641)State Key Laboratory of Safety and Control for Chemicals of China
文摘Crimped ribbon flame arresters are important safety devices in the chemical industry, especially for the danger- ous situations. Although proper design of arresters by the numerical simulation method is promising, its reliabil- ity and accuracy are dependent upon the mathematical model. In this work, an integrated mathematical model for the microchannel in the crimped ribbon flame attesters was set up; the fluid flow behavior and the sensitiv- ities of four chemical kinetics mechanisms of propane-air on the accuracy were analysed. It is shown that turbu- lence is predominant in the microchannel of the crimped ribbon flame arresters under the defiagration and detonation conditions, and a new quenching criterion for the numerical simulation is proposed. The kinetics mechanism of Mansouri et al. among the four ones is the most accurate due to the best agreement of the pre- dicted outlet temperature at the experimental flameproof velocity with the autoignition temperature of propane-air. The species mass fraction profiles and the temperature distribution, which are too difficult to mea- sure due to the tiny dimension of the microchannel in experiments, are captured. The fundamental insights into chemical reactions and heat loss are well portrayed. It can be concluded that the integrated mathematical model established in this work can be used as a reliable tool for modeling, selecting and designing such type of crimped ribbon flame attesters with the propane-air medium in the future.
文摘In this paper, controlling chaos when chaotic ferroresonant oscillations occur in a voltage transformer with nonlin- ear core loss model is performed. The effect of a parallel metal oxide surge arrester on the ferroresonance oscillations of voltage transformers is studied. The metal oxide arrester （MOA） is found to be effective in reducing ferroresonance chaotic oscillations. Also the multiple scales method is used to analyze the chaotic behavior and different types of fixed points in ferroresonance of voltage transformers considering core loss. This phenomenon has nonlinear chaotic dynamics and includes sub-harmonic, quasi-periodic, and also chaotic oscillations. In this paper, the chaotic behavior and various ferroresonant oscillation modes of the voltage transformer is studied. This phenomenon consists of different types of bifur- cations such as period doubling bifurcation （PDB）, saddle node bifurcation （SNB）, Hopf bifurcation （HB）, and chaos. The dynamic analysis of ferroresonant circuit is based on bifurcation theory. The bifurcation and phase plane diagrams are il- lustrated using a continuous method and linear and nonlinear models of core loss. To analyze ferroresonance phenomenon, the Lyapunov exponents are calculated via the multiple scales method to obtain Feigenbaum numbers. The bifurcation diagrams illustrate the variation of the control parameter. Therefore, the chaos is created and increased in the system.
基金funded from Taif University Researchers Supporting Project number(TURSP-2020/264),Taif University,Taif,Saudi Arabia.
文摘Rogowski coils(RCs)are widely used to measure power or high frequency currents based on their design.In this paper,two types of RCs that are circular(traditional)and cylindrical shapes wound using wire covered by varnish are constructed.This construction is carried out to be suitable for monitoring the discharge current of the surge arrester installed in the distribution system.Concerning high frequency RC modeling for both types considering transfer function is introduced.Self-integrating for both types is attained.Therefore,the experimental tests using function generator for both coils are carried out to identify the parameters of the transfer function representing the introduced model.The measured signals for current and induced voltages are denoised for the parameter identification process.The denoised process is achieved using the MATLAB code‘wdenoise’while the parameters are estimated using the system identification toolbox.Verification of the proposed model is achieved using experimental results for the two coils.The sensitivity of the two coils is investigated based on the induced output voltage.The application concerning the two coils for monitoring the discharge current of the surge arrester is done.The results confirm the accuracy of the introduced RC model,as well as the performance of the cylindrical shape,is better than the traditional one.The simulation is carried out using MATLAB and ATPDraw programs.
文摘Zinc Oxide (ZnO) surge arresters (SAs) experience thermal runaway when the temperature exceeds the acceptable limit. This phenomenon is associated with the increase in resistive leakage current due to degradation. This paper presents the electrical performance of ZnO SAs in 22 kV distribution systems using thermal image camera under the power frequency AC operating voltages. When ZnO surge arresters are installation takes a long time in distribution system over more than 5 years. For the experimental study, as ZnO installation takes a long time over 6 years the leakage current is 63.9 mA, temperature differences were measured over a period of time over 14 degree Celsius. This data will be useful as a guideline for solving problems and reducing power loss from leakage current. Moreover, it will be useful in predicting lifetime of ZnO SAs.
文摘Shanghai Electric Porcelain Works (SEPW), a subsidiary enterprise of the SEC (Group), is specialized in manufacturing highvoltage surge arresters and fuses as main products, as well as some high-voltage insulators, wall bushings and disconnecting switches for power transmission & distribution systems. In fact, SEPW is
文摘Due to important consideration of protection against lightning surge on electrical, electronic and telecommunication equipment, it was necessary to carry out a special study to look at the performance of protective devices. The study was testing performance of arresters on low voltage system. The activity was testing of arresters using steady state and impulse voltages. The arresters consisted of gas tube, zener diode, varistor and spark gap arresters, then it was made a cascade circuit between the varistor and spark gap arresters with a decoupling element. The decoupling elements were used air, iron and ferrite. The test yielded data of current and voltage on the tables and oscilloscope waveforms. The arresters had cut voltages early different from each other, namely the gas tube, zener diode, spark gap and varistor arresters were at the voltages of 500 V, 250 V, 1,000 V and 565 V respectively. The iron core decoupling element cascade circuit had the least oscillation among remaining cores.
文摘The resistance characteristics of a corrugated flame arrester in hydrogen explosions were investigated using a visual explosion-retardant system.By varying the structural parameters of the corrugated flame-retardant system and the concentration of hydrogen,the flame resistance characteristics and the mechanisms affecting hydrogen explosions were summarized.The results indicate that there was a clear correlation between the flame propagation and pressure rise during explosion resistance.When the flame resistance failed,a significant enhancement effect was observed at the backend of the flame-retardant system.Additionally,a noticeable oscillation occurred in the initial stage of flame propagation due to the obstruction caused by the flame-retardant system.The thickness and porosity of the flame-retardant system,along with the hydrogen concentration,influenced the intensities of shock waves and flames entering the narrow channel,as well as the physical and chemical effects during internal propagation,thereby affecting the overall flame resistance.
基金supported by the Natural Science Fund of Fujian Province,No.2020J011058(to JK)the Project of Fujian Provincial Hospital for High-level Hospital Construction,No.2020HSJJ12(to JK)+1 种基金the Fujian Provincial Finance Department Special Fund,No.(2021)848(to FC)the Fujian Provincial Major Scientific and Technological Special Projects on Health,No.2022ZD01008(to FC).
文摘Cardiac arrest can lead to severe neurological impairment as a result of inflammation,mitochondrial dysfunction,and post-cardiopulmonary resuscitation neurological damage.Hypoxic preconditioning has been shown to improve migration and survival of bone marrow–derived mesenchymal stem cells and reduce pyroptosis after cardiac arrest,but the specific mechanisms by which hypoxia-preconditioned bone marrow–derived mesenchymal stem cells protect against brain injury after cardiac arrest are unknown.To this end,we established an in vitro co-culture model of bone marrow–derived mesenchymal stem cells and oxygen–glucose deprived primary neurons and found that hypoxic preconditioning enhanced the protective effect of bone marrow stromal stem cells against neuronal pyroptosis,possibly through inhibition of the MAPK and nuclear factor κB pathways.Subsequently,we transplanted hypoxia-preconditioned bone marrow–derived mesenchymal stem cells into the lateral ventricle after the return of spontaneous circulation in an 8-minute cardiac arrest rat model induced by asphyxia.The results showed that hypoxia-preconditioned bone marrow–derived mesenchymal stem cells significantly reduced cardiac arrest–induced neuronal pyroptosis,oxidative stress,and mitochondrial damage,whereas knockdown of the liver isoform of phosphofructokinase in bone marrow–derived mesenchymal stem cells inhibited these effects.To conclude,hypoxia-preconditioned bone marrow–derived mesenchymal stem cells offer a promising therapeutic approach for neuronal injury following cardiac arrest,and their beneficial effects are potentially associated with increased expression of the liver isoform of phosphofructokinase following hypoxic preconditioning.
基金Supported by the National Nature Science Foundation of China (Grant Nos.50425721,5073001)the 11th Five-year National S&T Supporting Plan (Grant No.2006BAA02A16)
文摘The surge arrester with excellent protection characteristics would decrease the overvoltage level ap- plied on the power apparatus to reduce their insulation levels and manufacturing bottleneck. The arrester for the 1000-kV ultra-high voltage ac power transmission system is designed as tank-type structure. The field-circuit combination numerical method combining the three-dimensional finite element method with circuit is proposed to analyze the potential distribution of GIS arrester. By comparing several design schemes, the most effective method to improve the potential distribution along the varistor column is to increase the voltage gradient of the ZnO varistor. Synthesizing several influential factors, the suitable voltage gradient of ZnO varistor should be controlled to 435 V/mm, and the resulted nonuniform degree of the potential distribution along the varistor column inside the GIS arrester would be controlled smaller than 10%. The result in this paper provides the fundamental technical index for the study of the high voltage gradient ZnO varistors.
基金supported by General Administration of Quality Supervision,Inspection and Quarantine of China Scientific Project(Grant No.2011QK083)Shenyang Science and Technology Project(Grant No.F14-048-2-00)
文摘An experimental system that consisted of gas mixing equipment, a sensor detection system, a data acquisition device, and an electric spark ignition device was set up to investigate fuel/air deflagration flame propagation and quenching processes through a crimped-ribbon flame arrester in an enclosed horizontal pipe. Deflagration suppression experiments showed that when the concentration of flammable gas was close to the stoichiometric ratio, the evolution processes of explosion pressure for the propane-air and ethylene-air premixed gases in the pipe diameter （DN32-DN400） were similar and could be divided into four stages： isobaric combustion, slow pressure rise, quick pressure rise, and pressure oscillation. However, the explosion duration of the hydrogen-air premixed gas was relatively short, and the peak explosion pressure was high. The pressure rose quickly after the isobaric combustion stage. Therefore, the process can be divided into three stages in the pipe diameter （DN15-DN150）. Deflagration speed results indicated that the propane-air flame speed initially increased and eventually decreased along with increases in the pipe diameter （DN32-DN400）; however, the ethylene-air flame speed gradually increased with the increase of the pipe diameter （DNS0-DN400）. No notable pattern of change in the hydrogen-air flame speed was observed in the pipe diameter （DN15-DN150）. The maximum propane-air flame speed occurred at 5% concentration. The maximum flame speed for ethylene-air and hydrogen-air happened when the mixture was close to stoichiometric ratio. Under the conditions of the same size of experimental tube configuration and the same ignition distance but different pipe lengths, or the same pipe length but different ignition distances, experimental results showed that the flame arrester successfully stopped the flames at high flame speed and low explosion pressure, but failed at low flame speed and high explosion pressure.
基金supported by the National Natural Science Foundation of China(32170144 and 32470146).
文摘Severe fever with thrombocytopenia syndrome(SFTS)is a novel emerging acute infectious disease caused by severe fever with thrombocytopenia syndrome virus(SFTSV),characterized by high fever and thrombocytopenia.It has been proved that traditional Chinese medicine(TCM)has displayed definite therapeutic effects on viral hemorrhagic fever,indicating its potential to treat SFTS.In this study,SFTS-relative key targets were predicted via gene ontology(GO)analysis and kyoto encyclopedia of genes and genomes(KEGG)enrichment analysis.Molecular docking was then used to select stable binders.Molecules matched TCMs were identified,and a new prescription,Qingqi Guxue decoction(QQGX),was formulated to clear heat and nourish blood,with a resulting drug composition network.We explored the optimal drug proportion for QQGX.Through an in-depth study of molecular mechanisms,we found that QQGX induces S phase arrest by promoting the degradation of cyclin A2(CCNA2)and cyclin-dependent kinase 2(CDK2),thereby inhibiting SFTSV replication.Finally,we verified the effectiveness and safety of QQGX based on the mouse liver bile duct organoid model infected with SFTSV.In summary,our study prepared a TCM decoction using the method of network pharmacology.This decoction has a significant inhibitory effect on the replication of SFTSV and provides a new treatment strategy for hemorrhagic fever with TCM.
基金supported by the National Science Foundation of China,Nos.82325031(to FX),82030059(to YC),82102290(to YG),U23A20485(to YC)Noncommunicable Chronic Diseases-National Science and Technology Major Project,No.2023ZD0505504(to FX),2023ZD0505500(to YC)the Key R&D Program of Shandong Province,No.2022ZLGX03(to YC).
文摘Global brain ischemia and neurological deficit are consequences of cardiac arrest that lead to high mortality.Despite advancements in resuscitation science,our limited understanding of the cellular and molecular mechanisms underlying post-cardiac arrest brain injury have hindered the development of effective neuroprotective strategies.Previous studies primarily focused on neuronal death,potentially overlooking the contributions of non-neuronal cells and intercellular communication to the pathophysiology of cardiac arrest-induced brain injury.To address these gaps,we hypothesized that single-cell transcriptomic analysis could uncover previously unidentified cellular subpopulations,altered cell communication networks,and novel molecular mechanisms involved in post-cardiac arrest brain injury.In this study,we performed a single-cell transcriptomic analysis of the hippocampus from pigs with ventricular fibrillation-induced cardiac arrest at 6 and 24 hours following the return of spontaneous circulation,and from sham control pigs.Sequencing results revealed changes in the proportions of different cell types,suggesting post-arrest disruption in the blood-brain barrier and infiltration of neutrophils.These results were validated through western blotting,quantitative reverse transcription-polymerase chain reaction,and immunofluorescence staining.We also identified and validated a unique subcluster of activated microglia with high expression of S100A8,which increased over time following cardiac arrest.This subcluster simultaneously exhibited significant M1/M2 polarization and expressed key functional genes related to chemokines and interleukins.Additionally,we revealed the post-cardiac arrest dysfunction of oligodendrocytes and the differentiation of oligodendrocyte precursor cells into oligodendrocytes.Cell communication analysis identified enhanced post-cardiac arrest communication between neutrophils and microglia that was mediated by neutrophil-derived resistin,driving pro-inflammatory microglial polarization.Our findings provide a comprehensive single-cell map of the post-cardiac arrest hippocampus,offering potential novel targets for neuroprotection and repair following cardiac arrest.
基金supported by Progetto Trapezio,Compagnia di San Paolo(67935-2021.2174)to LB,Fondazione CRT(Cassa di Risparmio di Torino,RF=2022.0618)to LB。
文摘Brain plasticity-A universal tool with many variations:The study of brain plasticity has been gaining interest since almost a century and has now reached a huge amount of information(>80,000 results in PubMed).Overall,different types of plasticity,including stem cell-driven genesis of new neurons(adult neurogenesis),cells in arrested maturation(dormant neurons),neuro-glial and synaptic plasticity,can coexist and contribute to grant plastic changes in the brain,from a cellular to system level(Benedetti and Couillard-Despres,2022;Bonfanti et al.,2023).
文摘BACKGROUND Acute pancreatitis in pregnancy is a rare but serious condition that can lead to high maternal mortality and fetal loss.Instances of pregnancy complicated by severe acute pancreatitis,particularly with subsequent respiratory and cardiac arrest,are rarely reported.CASE SUMMARY We present the case of a 35-year-old woman,at 36+5 weeks of gestation,who presented with paroxysmal epigastric pain accompanied by low back pain,nausea,and vomiting.According to the clinical symptoms,B-ultrasound imaging and biochemical indicators,the patient was diagnosed with acute pancreatitis and initially managed conservatively.However,3 hours after admission,the patient experienced respiratory and cardiac arrest,and the fetus died.In this case,the adverse outcomes occurred due to the lack of aggressive fluid resuscitation and an active surgical intervention.CONCLUSION Implementing aggressive fluid resuscitation to sustain tissue perfusion,alongside the proactive evaluation of pharmacological agents that suppress gastric acid secretion and inhibit pancreatic enzyme activity,may be beneficial in mitigating the risk of a severely adverse prognosis.Effective management of acute pancreatitis during pregnancy requires careful timing of surgical intervention,a thorough evaluation of the risks and benefits regarding the continuation or termination of pregnancy,and a focus on safeguarding both maternal and fetal health.
基金supported by the National Key Research and Development Program(2021YFC3002205)the Postgraduate Research and Innovation Program of Tianjin Municipal Education Commission(2022BKY113),China.
文摘Cardiac arrest(CA)is a critical condition in the field of cardiovascular medicine.Despite successful resuscitation,patients continue to have a high mortality rate,largely due to post CA syndrome(PCAS).However,the injury and pathophysiological mechanisms underlying PCAS remain unclear.Experimental animal models are valuable tools for exploring the etiology,pathogenesis,and potential interventions for CA and PCAS.Current CA animal models include electrical induction of ventricular fibrillation(VF),myocardial infarction,high potassium,asphyxia,and hemorrhagic shock.Although these models do not fully replicate the complexity of clinical CA,the mechanistic insights they provide remain highly relevant,including post-CA brain injury(PCABI),post-CA myocardial dysfunction(PAMD),systemic ischaemia/reperfusion injury(IRI),and the persistent precipitating pathology.Summarizing the methods of establishing CA models,the challenges encountered in the modeling process,and the mechanisms of PCAS can provide a foundation for developing standardized CA modeling protocols.
基金Supported by Scientific Research Projects from Wuhan Municipal Health Commission of China,No.WX23B42.
文摘BACKGROUND Cardiac arrest caused by acute pulmonary embolism(PE)is the most serious clinical circumstance,necessitating rapid identification,immediate cardiopulmonary resuscitation(CPR),and systemic thrombolytic therapy.Extracorporeal CPR(ECPR)is typically employed as a rescue therapy for selected patients when conventional CPR is failing in settings where it can be implemented.CASE SUMMARY We present a case of a 69-year-old male who experienced a prolonged cardiac arrest in an ambulance with pulseless electrical activity.Upon arrival at the emergency department with ongoing manual chest compressions,bedside pointof-care ultrasound revealed an enlarged right ventricle without contractility.Acute PE was suspected as the cause of cardiac arrest,and intravenous thrombolytic therapy with 50 mg tissue plasminogen activator was administered during mechanical chest compressions.Despite 31 minutes of CPR,return of spontaneous circulation was not achieved until 8 minutes after initiation of Veno-arterial extracorporeal membrane oxygenation(ECMO)support.Under ECMO support,the hemodynamic status and myocardial contractility significantly improved.However,the patient ultimately did not survive due to intracerebral hemorrhagic complications,leading to death a few days later in the hospital.CONCLUSION This case illustrates the potential of combining systemic thrombolysis with ECPR for refractory cardiac arrest caused by acute PE,but it also highlights the increased risk of significant bleeding complications,including fatal intracranial hemorrhage.
基金supported by the Regional Science Foundation Project of the National Natural Science Foundation of China(Project No:82160157)the Beijing High-Level Public Health Technology Talent Construction Project(Project No.:Leading Talents-03-10).
文摘Cardiac arrest(CA)is considered a state of clinical death in which the heart suddenly loses its ability to effectively expel blood,resulting in circulatory and respiratory arrest.CA is often catastrophic for patients,as it can cause serious long-term cardiovascular and cerebrovascular complications that affect their quality of life[1].Survey data indicate that the overall incidence rate of intraoperative CA in patients undergoing thoracic surgery in China is currently 0.138%[2].This rate is expected to increase because of the increasing proportion of older individuals(age>60 years)in the population,as well as the increasing pulmonary surgery rates.However,the incidence rate during the perianesthetic period in older patients undergoing thoracic surgery has not yet been comprehensively reported.
基金Supported by the National Natural Science Foundation of China(No. 50737001)
文摘The amplitude of switching overvoltages is a key factor for designing the insulation of UHV equipment. The effect of different arresters needs to be studied, since installing arresters is an important way to suppress switching overvoltages in UHV transmission lines. Switching overvoltages on the 1000 kV Huainan-Huxi double-circuit transmission line were simulated for different operating modes and different arrester designs using the electromagnetic transient program PSCAD/EMTDC. With parallel resistors, the switching overvoltages are less than 1.70 p.u. （1.0 p.u.=1100×√ 2 /√3 kV）. If the arrestors are better, the switching overvoltages can be reduced even lower to 1.55 p.u. Without parallel resistors, the arresters can reduce three-phase energizing overvoltages to 1.70 p.u, while the single-phase reclosing overvoltages still exceed the limit. The results show that the parallel resistors cannot be eliminated if the arresters are only installed at each end of the transmission line. Also, better quality arresters significantly lower the switching overvoltages.
基金supported by the National High Level Hospital Clinical Research Funding (2022-NHLHCRF-YS-03)the National Natural Science Foundation of China (82272196)。
文摘BACKGROUND:Post-cardiac arrest syndrome(PCAS) significantly contributes to mortality after initially successful cardiopulmonary resuscitation(CPR) in cardiac arrest(CA) patients.Effective cardiocerebral protection is essential for improving post-resuscitation survival.This study investigated the mechanisms and common targets of myocardial dysfunction and brain injury after resuscitation.METHODS:The male Sprague-Dawley rats(10–12 weeks old,400–500 g) were divided into two groups:the control group(n=6),which received sham surgery,and the CA/CPR group(n=10),which received ventricular fibrillation(VF) followed by CPR.After 24 h,brain and heart tissues were collected for analysis.The sequencing was used to identify differentially expressed genes(DEGs) between control and CA/CPR rats.RESULTS:At 24 h after resuscitation,CA/CPR rats presented 217 DEGs in the hippocampus and 80 DEGs in the left ventricle(LV) compared to the control group.In the hippocampus,the most notable biological process was the positive regulation of tumor necrosis factor production,with key pathways related to inflammation and the immune response.In the LV,the Gene Ontology(GO)enrichment analysis revealed that gene alterations were primarily associated with amyloid-beta clearance,a pathway that was also relevant in the brain.Eleven common targets were identified in the DEGs of both heart and brain tissues.The reverse transcription-polymerase chain reaction(RTPCR) validation revealed significant differences in the mRNA expression of Timp1,Apln,Ccl7,and Lgals3 in both LV and hippocampus.CONCLUSION:This study identified possible key genes and underlying mechanisms involved in PCAS.The differential genes Timp1,Apln,Ccl7,and Lgals3 might serve as common biomarkers for myocardial and neurological injury following resuscitation.
文摘Modern cardiopulmonary resuscitation(CPR)has been established for more than 60 years;however,its success rate remains low.Currently,the global incidence of out-of-hospital cardiac arrest(OHCA)is rising,ranging from 52.5 to 97.1 per 100,000 population.[1,2]Survival-to-discharge rates for OHCA and in-hospital cardiac arrest(IHCA)are not satisfactory,with ranges of 1.2%-9.9%and 9.1%-19.1%,respectively.
