The high temperature properties of AISI 304 stainless steel were studied. Basic data about the employed experimental equipment, testing procedures, and specimen geometry were given. The experimental setup was used to ...The high temperature properties of AISI 304 stainless steel were studied. Basic data about the employed experimental equipment, testing procedures, and specimen geometry were given. The experimental setup was used to obtain stress-strain diagrams from tensile tests at room temperature as well as several elevated temperatures. Furthermore, the specimens were subjected to short-time creep tests at various temperatures. Stress levels for creep testing were established as a percentage of yield stress. The results indicate that at lowered temperatures and lower stress levels, AISI 304 stainless steel can be used as a sufficiently creep resistant material.展开更多
The lubricant behaviour at elevated temperatures was investigated by conducting pin-on-disc tests between P20 tool steel and AA7075 aluminium alloy. The effects of temperature, initial lubricant volume, contact pressu...The lubricant behaviour at elevated temperatures was investigated by conducting pin-on-disc tests between P20 tool steel and AA7075 aluminium alloy. The effects of temperature, initial lubricant volume, contact pressure and sliding speed on the lubricant behaviour(i.e. evolutions of the coefficient of friction(COF) and the breakdown phenomenon) were experimentally studied. The evolutions of COF at elevated temperatures consisted of three distinct stages with different friction mechanisms. The first stage(stage Ⅰ) occurred with low friction when the boundary lubrication was present. The second stage(stage Ⅱ) was the transition process in which the COF rapidly increased as the lubricant film thickness decreased to a critical value. In the final plateau stage(stage Ⅲ), lubricant breakdown occurred and intimate contact at the interface led to high friction values. At the low friction stage(stage Ⅰ), the value of COF increased with increasing temperature. The increase in temperature, contact pressure and sliding speed as well as the decrease in initial lubricant volume accelerated the lubricant breakdown.展开更多
BACKGROUND Severe acute respiratory syndrome coronavirus 2,or coronavirus disease-2019(COVID-19),has infected millions worldwide since its discovery in Wuhan,China in December 2019,but little is still known about the ...BACKGROUND Severe acute respiratory syndrome coronavirus 2,or coronavirus disease-2019(COVID-19),has infected millions worldwide since its discovery in Wuhan,China in December 2019,but little is still known about the disease process.Preliminary research in China notes liver function tests(LFTs)abnormalities are common in COVID-19 patients,suggesting decreased hepatic function,and that abnormalities in LFTs are related to complicated disease course and negative outcomes.However,there has been limited large-scale data assessing COVID-19’s association with liver dysfunction and negative outcomes.AIM To investigate how COVID-19 affects the liver function and disease course in patients infected with the virus treated at Henry Ford Hospital from March to September 2020.METHODS A total of 8028 patients infected with COVID-19 were identified and included in the study at a single academic center.Data from medical charts on laboratory testing including aspartate aminotransferase(AST),alanine aminotransferase(ALT),alkaline phosphatase(AP),and bilirubin levels,past history of liver disease,and disease course indicators including hospital admission,intensive care unit(ICU)admission,intubation,and death were recorded and analyzed.Elevated liver enzymes were defined as ALT/AST greater than 60,AP greater than 150,or bilirubin greater than 1.5,super-elevated liver enzymes were defined as ALT/AST greater than 120,AP greater than 300,or bilirubin greater than 3.0.RESULTS A total of 8028 COVID-19 patients were identified and included in the study.Data from medical charts on LFTs(namely,AST,ALT,AP,and bilirubin levels),past history of liver disease,and disease course indicators(hospital/ICU admission,intubation,death)were recorded and analyzed.LFTs from 3937 patients were available for interpretation.45% were found to have elevated or super-elevated LFT.When compared to COVID-19 patients without elevated LFTs,this cohort was found to have significantly higher odds of hospital admittance,ICU admission,intubation,and death(all P<0.001).248(3.1%)had a history of liver disease.Those with elevated and super elevated LFTS had significantly higher odds of having a past history of liver disease(P<0.001).CONCLUSION The findings from this study suggest that in patients who have tested positive for COVID-19,those with elevated and super elevated liver enzyme levels have significantly higher odds of hospital admittance,ICU admittance,intubation and death in comparison to those COVID-19 patients without elevated liver enzyme levels.展开更多
Pressure guide plate plays a certain role in the safe operation of elevator.Based on understanding the respective performance of new and old pressure guide plates,this paper analyses the problems existing in the origi...Pressure guide plate plays a certain role in the safe operation of elevator.Based on understanding the respective performance of new and old pressure guide plates,this paper analyses the problems existing in the original pressure guide plate.It also conducts stress analysis according to the function of pressure guide plate on elevator,and designs a new type of pressure guide plate combined with technological capability and equipment.According to the stress characteristics,a test device is designed and a comparative test is made between the new type of pressure guide plate and the old in order to test the reliability of the new type of pressure guide plate.The test proves that the new pressure guide plate of elevator can meet the requirements of product use and safe operation of elevator products.展开更多
Anxiety is a significant mental health issue that substantially affects an individual’s quality of life. Feelings of uneasiness, irritability, and sleep disturbances characterize it. 4-Hydroxyphenyl acetic acid (4-HP...Anxiety is a significant mental health issue that substantially affects an individual’s quality of life. Feelings of uneasiness, irritability, and sleep disturbances characterize it. 4-Hydroxyphenyl acetic acid (4-HPAA) is identified in brain cells as a physiological byproduct of tyramine. This study hypothesizes that 4-HPAA may regulate anxiety due to its anxiolytic properties, acting as a modulator of the GABAergic system, which plays a crucial role in the pathophysiology of anxiety disorders. Our study aims to enhance the anxiolytic effects of 4-HPAA through chemical modification to improve its pharmacokinetic properties. Three derivatives, namely Isopropyl-4-hydroxy-[phenyl] acetate (IHPA), Isopropyl-4-hydroxy-[phenyl] acetate (MPAA), and 4-methoxyphenyl acetate (MPHA), have been synthesized from 4-HPAA. This assessment will use well-established animal models, specifically the Elevated Plus-Maze (EPM) and Zero Maze (EZM) tests, selected for their validity in replicating anxiety-like symptoms in animals. Chronic caffeine administration via drinking water (0.3 g/l for 14 days) was employed to induce an anxiety state for testing purposes. IHPA and MPAA demonstrated significant anxiolyticactivity when tested in the EPM and EZM experiments. Molecular docking simulations using AutoDock Vina indicated that 4-HPAA derivatives had docking scores ranging from −5.8 to −4.8 kcal/mol, compared to the standard anxiolytic medication Diazepam, which scored −7.1 kcal/mol. These scores suggest a potential for 4-HPAA derivatives to interact effectively with the Gamma-aminobutyric acid (GABA_A) receptor. In conclusion, our in vivo and in silico analyses indicate a promising anxiolytic potential for 4-HPAA derivatives.展开更多
基金supported by the Ministry of Science and Technology of the Republic of Croatia,titled "Numerical analysis of structural response for specific service conditions" (No.069-0691736-1737)
文摘The high temperature properties of AISI 304 stainless steel were studied. Basic data about the employed experimental equipment, testing procedures, and specimen geometry were given. The experimental setup was used to obtain stress-strain diagrams from tensile tests at room temperature as well as several elevated temperatures. Furthermore, the specimens were subjected to short-time creep tests at various temperatures. Stress levels for creep testing were established as a percentage of yield stress. The results indicate that at lowered temperatures and lower stress levels, AISI 304 stainless steel can be used as a sufficiently creep resistant material.
基金supported by the China Scholarship Council (Grant CSC No. 201706230235): a nonprofit institution that enables talented Chinese students to participate in overseas Ph D programs。
文摘The lubricant behaviour at elevated temperatures was investigated by conducting pin-on-disc tests between P20 tool steel and AA7075 aluminium alloy. The effects of temperature, initial lubricant volume, contact pressure and sliding speed on the lubricant behaviour(i.e. evolutions of the coefficient of friction(COF) and the breakdown phenomenon) were experimentally studied. The evolutions of COF at elevated temperatures consisted of three distinct stages with different friction mechanisms. The first stage(stage Ⅰ) occurred with low friction when the boundary lubrication was present. The second stage(stage Ⅱ) was the transition process in which the COF rapidly increased as the lubricant film thickness decreased to a critical value. In the final plateau stage(stage Ⅲ), lubricant breakdown occurred and intimate contact at the interface led to high friction values. At the low friction stage(stage Ⅰ), the value of COF increased with increasing temperature. The increase in temperature, contact pressure and sliding speed as well as the decrease in initial lubricant volume accelerated the lubricant breakdown.
文摘BACKGROUND Severe acute respiratory syndrome coronavirus 2,or coronavirus disease-2019(COVID-19),has infected millions worldwide since its discovery in Wuhan,China in December 2019,but little is still known about the disease process.Preliminary research in China notes liver function tests(LFTs)abnormalities are common in COVID-19 patients,suggesting decreased hepatic function,and that abnormalities in LFTs are related to complicated disease course and negative outcomes.However,there has been limited large-scale data assessing COVID-19’s association with liver dysfunction and negative outcomes.AIM To investigate how COVID-19 affects the liver function and disease course in patients infected with the virus treated at Henry Ford Hospital from March to September 2020.METHODS A total of 8028 patients infected with COVID-19 were identified and included in the study at a single academic center.Data from medical charts on laboratory testing including aspartate aminotransferase(AST),alanine aminotransferase(ALT),alkaline phosphatase(AP),and bilirubin levels,past history of liver disease,and disease course indicators including hospital admission,intensive care unit(ICU)admission,intubation,and death were recorded and analyzed.Elevated liver enzymes were defined as ALT/AST greater than 60,AP greater than 150,or bilirubin greater than 1.5,super-elevated liver enzymes were defined as ALT/AST greater than 120,AP greater than 300,or bilirubin greater than 3.0.RESULTS A total of 8028 COVID-19 patients were identified and included in the study.Data from medical charts on LFTs(namely,AST,ALT,AP,and bilirubin levels),past history of liver disease,and disease course indicators(hospital/ICU admission,intubation,death)were recorded and analyzed.LFTs from 3937 patients were available for interpretation.45% were found to have elevated or super-elevated LFT.When compared to COVID-19 patients without elevated LFTs,this cohort was found to have significantly higher odds of hospital admittance,ICU admission,intubation,and death(all P<0.001).248(3.1%)had a history of liver disease.Those with elevated and super elevated LFTS had significantly higher odds of having a past history of liver disease(P<0.001).CONCLUSION The findings from this study suggest that in patients who have tested positive for COVID-19,those with elevated and super elevated liver enzyme levels have significantly higher odds of hospital admittance,ICU admittance,intubation and death in comparison to those COVID-19 patients without elevated liver enzyme levels.
文摘Pressure guide plate plays a certain role in the safe operation of elevator.Based on understanding the respective performance of new and old pressure guide plates,this paper analyses the problems existing in the original pressure guide plate.It also conducts stress analysis according to the function of pressure guide plate on elevator,and designs a new type of pressure guide plate combined with technological capability and equipment.According to the stress characteristics,a test device is designed and a comparative test is made between the new type of pressure guide plate and the old in order to test the reliability of the new type of pressure guide plate.The test proves that the new pressure guide plate of elevator can meet the requirements of product use and safe operation of elevator products.
文摘Anxiety is a significant mental health issue that substantially affects an individual’s quality of life. Feelings of uneasiness, irritability, and sleep disturbances characterize it. 4-Hydroxyphenyl acetic acid (4-HPAA) is identified in brain cells as a physiological byproduct of tyramine. This study hypothesizes that 4-HPAA may regulate anxiety due to its anxiolytic properties, acting as a modulator of the GABAergic system, which plays a crucial role in the pathophysiology of anxiety disorders. Our study aims to enhance the anxiolytic effects of 4-HPAA through chemical modification to improve its pharmacokinetic properties. Three derivatives, namely Isopropyl-4-hydroxy-[phenyl] acetate (IHPA), Isopropyl-4-hydroxy-[phenyl] acetate (MPAA), and 4-methoxyphenyl acetate (MPHA), have been synthesized from 4-HPAA. This assessment will use well-established animal models, specifically the Elevated Plus-Maze (EPM) and Zero Maze (EZM) tests, selected for their validity in replicating anxiety-like symptoms in animals. Chronic caffeine administration via drinking water (0.3 g/l for 14 days) was employed to induce an anxiety state for testing purposes. IHPA and MPAA demonstrated significant anxiolyticactivity when tested in the EPM and EZM experiments. Molecular docking simulations using AutoDock Vina indicated that 4-HPAA derivatives had docking scores ranging from −5.8 to −4.8 kcal/mol, compared to the standard anxiolytic medication Diazepam, which scored −7.1 kcal/mol. These scores suggest a potential for 4-HPAA derivatives to interact effectively with the Gamma-aminobutyric acid (GABA_A) receptor. In conclusion, our in vivo and in silico analyses indicate a promising anxiolytic potential for 4-HPAA derivatives.
