De novo combined lamivudine and adefovir dipivoxil therapy vs entecavir monotherapy for hepatitis B virus-related decompensated cirrhosis

AIM:To compare efficacy of combined lamivudine(LAM)and adefovir dipivoxil(ADV)therapy with that of entecavir(ETV)monotherapy for hepatitis B virus(HBV)-related decompensated liver cirrhosis.METHODS:A total of 120 na ve patients with HBVrelated decompensated cirrhosis participated in this study.Sixty patients were treated with combined LAM and ADV therapy(LAM+ADV group),while the other60 were treated with ETV monotherapy(ETV group)for two years.Tests for liver and kidney function,alpha-fetoprotein,HBV serum markers,HBV DNA load,prothrombin time(PT),and ultrasonography or computed tomography scan of the liver were performed every1 to 3 mo.Repeated measure ANOVA and theχ2test were performed to compare the efficacy,side effects,and the cumulative survival rates at 48 and 96 wk.RESULTS:Forty-five patients in each group were observed for 96 wk.No significant differences in HBV DNA negative rates and alanine aminotransferase(ALT)normalization rates at weeks 48(χ2=2.12 and 2.88)and96(χ2=3.21 and 3.24)between the two groups were observed.Hepatitis B e antigen seroconversion rate in the LAM+ADV group at week 96 was significantly higher in the ETV group(43.5%vs 36.4%,χ2=4.09,P<0.05).Viral breakthrough occurred in 2 cases(4.4%)by week 48 and in 3 cases(6.7%)by week 96 in the LAM+ADV group,and no viral mutation was detected.In the ETV group,viral breakthrough occurred in 1 case(2.2%)at the end of week 96.An increase in albumin(F=18.9 and 17.3),decrease in total bilirubin and in ALT(F=16.5,17.1 and 23.7,24.8),reduced PT(F=22.7 and 24.5),and improved Child-Turcotte-Pugh and the model for end-stage liver disease scores(F=18.5,17.8,and 24.2,23.8)were observed in both groups.The cumulative rates of mortality and liver transplantation were 16.7%(10/60)and 18.3%(11/60)in the LAM+ADV and ETV groups,respectively.CONCLUSION:Both LAM+ADV combination therapy and ETV monotherapy can effectively inhibit HBV replication,improve liver function,and decrease mortality.

Early kidney injury during long-term adefovir dipivoxil therapy for chronic hepatitis B

AIM: To evaluate urine β2-microglobulin(β2-M), retinol-binding protein(RBP) excretion, and renal impairment with adefovir dipivoxil(ADV) for chronic hepatitis B. METHODS: We enrolled 165 patients with chronic hepatitis B infection who were treated with ADV monotherapy(n = 90) or ADV plus lamivudine combination therapy(n = 75). An additional 165 chronic hepatitis B patients treated with entecavir were recruited as controls. We detected serum creatinine, urine β2-M, and RBP levels, and estimated the glomerular filtration rate(e GFR) at the initiation of antiviral therapy and every 6 mo for a period of five years. RESULTS: Urine β2-M abnormalities were observed in patients during the first(n = 3), second(n = 7), third(n = 11), fourth(n = 16), and fifth(n = 21) year of ADV treatment. Urinary RBP abnormalities were observed in patients during the first(n = 2), second(n = 8), third(n = 12), fourth(n = 15), and fifth(n = 22) year of ADV treatment. e GFR decreased 20%-30% from baseline in 20 patients, 30%-50% in 12 patients, and > 50% in 3 patients during the five years of treatment. Further analysis indicated that decreases in e GFR of ≥ 30% relative to the baseline level correlated significantly with urine RBP and β2-M abnormalities. In contrast, both serum creatinine and e GFR remained stable in patients treated with entecavir, and only one of these patients developed a urine β2-M abnormality, and two developed urine RBP abnormalities during the five years of treatment. CONCLUSION: Urine RBP and β2-M are biomarkers of renal injury during long-term ADV treatment for chronic hepatitis B, and indicate when treatment should be switched to entecavir.

Hepatitis B surface antigen levels during natural history of chronic hepatitis B: A Chinese perspective study

AIM: To determine the baseline hepatitis B surface antigen (HBsAg) levels during the different phases of chronic hepatitis B (CHB) patients in China.

Bearing mechanism and thickness optimization of ore roof in bauxite stope

Based on the elastic thin plate theory,the main law of the ore roof failure was analyzed and the formula of the ore roof thickness was deduced.The results show that the tensile stress in the roof center accounts for the roof failure.According to the limit failure conditions of the point,the formula of the ore roof thickness was derived.Taking No.10 stope of a bauxite mine as an engineering case,the optimal thickness of the ore roof was 0.36 m.The safety factor was taken as 1.3,therefore the design thickness was 0.5 m.In the whole industrial test process,the dynamic alarm devices did not start the alarm and the ore roof was not damaged.Compared with other stopes under similar conditions,its thickness was reduced by 0.1-0.3 m.The recovery rate of the ore roof was increased by 16.7%-37.5%.

Meso-damage evolution and mechanical characteristics of low-porosity sedimentary rocks under uniaxial compression

Low pore sedimentary rocks(from Guangxi, China) were subjected to uniaxial compression loading experiment under different initial stresses. The rock samples were investigated by nuclear magnetic resonance before and after the loading. The relationships between the mesoscopic rock damage and macroscopic mechanical parameters were established, and the initial damage stress of the low-porosity sedimentary rock was determined. The results showed that this type of rock has the initial stress of damage. When the initial loading stress is lower than the initial stress of damage, the T2 spectrum area of the rock sample gradually decreases, and the primary pores of the rock are further closed under the stress. The range of the initial stress of damage for this type of rock is 8-16 MPa. When the loading stress exceeds the initial stress of damage, the T2 spectrum area gradually increases, indicating that the porosity of the rock increases and microscopic damage of the rock appears. The rock damage degree is defined, and the nonlinear function between the rock damage degree and the initial loading stress is established.

Serum chitinase-3-like protein 1 is a biomarker of liver fibrosis in patients with chronic hepatitis B in China

Background:Serum chitinase-3-like protein 1(CHI3L1)is a potential biomarker for fibrosis assessment.We aimed to evaluate serum CHI3L1 as a noninvasive diagnostic marker for chronic hepatitis B virusrelated fibrosis.Methods:Serum CHI3L1 levels were measured by ELISA in 134 chronic hepatitis B(CHB)patients.Significant fibrosis was defined as a liver stiffness>9.7 kPa.The performance of CHI3L1 was assessed and compared to that of other noninvasive tests by receiver operating characteristic(ROC)analysis.Results:Serum CHI3L1 levels were significantly higher in CHB patients with significant hepatic fibrosis(≥F2)than in those without significant hepatic fibrosis(<F2)(56.5 ng/mL vs.81.9 ng/mL,P<0.001).In CHB patients,the specificity and sensitivity of CHI3L1 for predicting significant fibrosis were 75.6%and 59.1%,respectively,with a cut-off of 76.0 ng/mL and an area under the ROC curve of 0.728(95%CI:0.637–0.820).Conclusions:Serum CHI3L1 levels could be an effective new serological biomarker for the diagnosis of liver fibrosis.Moreover,CHI3L1 is feasible in monitoring disease progression.

Cross-scale characteristics of backfill material using NMR and fractal theory

This paper analyzed the pore structure, quantified the pore fractal dimension, calculated the grading index(GI) of mixed aggregate, and studied the relationship among GI, pore structure, and strength to describe the cross-scale characteristics of backfill, which is made from stone powder and cemented tailing. A series of experiments were conducted on stone powder cement tailings backfill(SPCTB). The GI formulas for mixed aggregates, containing stone powder and tailings, were derived based on the Füller theory. The nuclear magnetic resonance(NMR) fractal dimensions of backfills were derived using fractal geometry principles. Compared to the mesopore and macropore fractal dimensions, the correlation between micropore fractal dimension and macro-properties in terms of NMR porosity, pore structure complexity, uniaxial compression strength(UCS), and GI is the most significant. Macropore fractal dimension is generally correlated with UCS and GI and the other properties such as the shape of mixed aggregates also have an impact on fractal dimension. However, mesopore fractal dimension has no obvious relationship with macro-properties. Finally, the relationship between GI and UCS was studied, which contributed to improving backfill’s strength and optimizing gradation.

Macroscopic and microscopic trans-scale characteristics of pore structure of mine grouting materials

The pore structure and porosity of three kinds of mine grouting materials were characterized based on a thin-section analysis and low-field nuclear magnetic resonance (NMR) technique. The macroscopic pore interconnectivity was investigated using binary images captured from thin sections and a random walk pore spectral dimension (RWPSD) algorithm. The experimental results show that the microstructure of the grouting materials used consisted of interlayer pores, gel pores, capillary pores, circular air holes, and small fractures, and tailings can fill some gaps in the hydration product structure and dense hydration products. There is a positive correlation between pore interconnectivity and curing time. In addition, there is a relationship between pore interconnectivity and porosity. With increasing porosity and pore interconnectivity, a non-uniform pore structure occurs in mine grouting materials with an accelerator and results in reduced setting time and later strength.

Calibration of anisotropic yield function by introducing plane strain test instead of equi-biaxial tensile test

The equi-biaxial tensile test is often required for parameter identification of anisotropic yield function and it demands thespecial testing technique or device. Instead of the equi-biaxial tensile test, the plane strain test carried out with the traditional uniaxialtesting machine is suggested to provide the experimental data for calibration of anisotropic yield function. This simplified method byusing plane strain test was adopted to identify the parameters of Yld2000-2d yield function for 5xxx aluminum alloy and AlMgSialloy sheets. The predicted results of yield stresses, anisotropic coefficients and yield loci by the proposed method were very similarwith the experimental data and those by the equi-biaxial tensile test. It is validated that the plane strain test is effective to provideexperimental data instead of equi-biaxial tensile test for calibration of Yld2000-2d yield function.

Kinetic Characterization of Tyrosinase-catalyzed Oxidation of Four Polyphenols

Phenolic compounds such as chlorogenic acid,cryptochlorogenic acid,neochlorogenic acid and caffeic acid are widely distributed in fruits,vegetables and traditional Chinese medicines with a wide range of biological activities.Tyrosinase plays a critical role in the food industry,but recent studies have proposed unexplored aspects of clinical application.Tyrosinase-catalyzed oxidation of four polyphenols as well as its underlying mechanism remains unclear.In the current work,we investigated the kinetic properties of tyrosinase-catalyzed oxidation of the four polyphenols of interest.To measure the unstable o-quinone products,an analytical method using 3-methyl-2-benzothiazolinone hydrazone(MBTH)was established.The optimal incubation time,buffer pH,temperature and enzyme concentration for the enzyme activity in the presence of each polyphenol of interest were investigated.Under the final optimized conditions,the kinetics and substrate specificity of four polyphenols were examined.K inetic data showed that tyrosinase had the greatest substrate affinity to chlorogenic acid compared with its isomers and caffeic acid.The catalytic efficiency with chlorogenic acid was 8-to 15-fold higher than that with the other 3 polyphenols.Molecular docking study demonstrated that the tight binding of chlorogenic acid at the peripheral site should be the major reason for the specificity to chlorogenic acid.In light of this,the rational design of high-affinity inhibitors against tyrosinase may focus on the binding of both the Cu site and peripheral site.This study will supply a basis for the selection of phenolic acids in food industry and health carc.

Microscale deformation behavior of sandstone mineral particles based on XCT scanning

This work aimed to quantify the physical and mechanical behavior of three-dimensional microstructures in rocks under uniaxial compression.A high-precision in situ XCT(X-ray transmission computed tomography)technology was applied to investigating the behavior of mineral grains in sandstone:the movement,the rotation deformation,and the principal strains between fault zone and non-fault zone.The results indicate that after unloading,the shear strain of mineral grains is periodic in the radial direction,the strain of mineral grains in the fracture zone is about 30 times of the macro strain of the specimen,which is about 5 times in the non-fracture zone,and the shear strain near the fault zone is larger than the compressive strain,and there is the shear stress concentration feature.

Molecular rotation-caused autocorrelation behaviors of thermal noise in water

The finite autocorrelation time of thermal noise is crucial to unidirectional transportation on the molecular scale.Therefore,it is important to understand the cause of the intrinsic picosecond autocorrelation time of thermal noise in water.In this work,we use molecular dynamics simulations to compare the autocorrelation behaviors of the thermal noise,hydrogen bonds,and molecular rotations found in water.We found that the intrinsic picosecond autocorrelation time for thermal noise is caused by finite molecular rotation relaxation,in which hydrogen bonds play the role of a bridge.Furthermore,the simulation results show that our method of calculating the autocorrelation of thermal noise,by observing the fiuctuating force on an oxygen atom of water,provides additional information about molecular rotations.Our findings may advance the understanding of the anomalous dynamic nanoscale behavior of particles,and the applications of terahertz technology in measuring the structural and dynamical information of molecules in solutions.

Surgical timing for primary encapsulating peritoneal sclerosis: A case report and review of literature

BACKGROUND Primary encapsulating peritoneal sclerosis(EPS)is a rare but devastating disease that causes fibrocollagenous cocoon-like encapsulation of the bowel,resulting in bowel obstruction.The pathogenesis,prevention,and treatment strategies of EPS remain unclear so far.Since most patients are diagnosed during exploratory laparotomy,for the non-surgically diagnosed patients with primary EPS,the surgical timing is also uncertain.CASE SUMMARY A 44-year-old female patient was referred to our center on September 6,2021,with complaints of abdominal distention and bilious vomiting for 2 d.Physical examination revealed that the vital signs were stable,and the abdomen was slightly distended.Computerized tomography scan showed a conglomerate of multiple intestinal loops encapsulated in a thick sac-like membrane,which was surrounded by abdominal ascites.The patient was diagnosed with idiopathic EPS.Recovery was observed after abdominal paracentesis,and the patient was discharged on September 13 after the resumption of a normal diet.This case raised a question:When should an exploratory laparotomy be performed on patients who are non-surgically diagnosed with EPS.As a result,we conducted a review of the literature on the clinical manifestations,intraoperative findings,surgical methods,and therapeutic effects of EPS.CONCLUSION Recurrent intestinal obstructions and abdominal mass combined with the imaging of encapsulated bowel are helpful in diagnosing idiopathic EPS.Small intestinal resection should be avoided.

Erratum to:Kinetic Characterization of Tyrosinase-catalyzed Oxidation of Four Polyphenols

The article“Kinetic Characterization of Tyrosinase-catalyzed Oxidation of Four Polyphenols”,written by Wan-yu LIU,Cong-ming ZOU,Jian-hua HU,Zi-jun XU,Lu-qin SI,Jun-jun LIU,Jian-geng HUANG,was originally published electronically on the publisher’s internet portal on May 2020 without open access.With the author(s)’decision to opt for Open Choice,the copyright of the article is changed to©The Author(s)2020 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License(https://creativecommons.org/licenses/by/4.0/),which permits use,sharing,adaptation,distribution and reproduction in any medium or format,as long as you give appropriate credit to the original author(s)and the source,provide a link to the Creative Commons license,and indicate if changes were made.

Efficacy and safety of the long-acting fusion inhibitor albuvirtide in antiretroviral-experienced adults with human immunodeficiency virus-1:interim analysis of the randomized,controlled,phase 3,non-inferiority TALENT study

Background:Albuvirtide is a once-weekly injectable human immunodeficiency virus(HIV)-1 fusion inhibitor.We present interim data for a phase 3 trial assessing the safety and efficacy of albuvirtide plus lopinavir-ritonavir in HIV-1-infected adults already treated with antiretroviral drugs.Methods:We carried out a 48-week,randomized,controlled,open-label non-inferiority trial at 12 sites in China.Adults on the World Health Organization(WHO)-recommended first-line treatment for>6 months with a plasma viral load>1000 copies/mL were enrolled and randomly assigned(1:1)to receive albuvirtide(once weekly)plus ritonavir-boosted lopinavir(ABT group)or the WHO-recommended second-line treatment(NRTI group).The primary endpoint was the proportion of patients with a plasma viral load below 50 copies/mL at 48 weeks.Non-inferiority was prespecified with a margin of 12%.Results:At the time of analysis,week 24 data were available for 83 and 92 patients,and week 48 data were available for 46 and 50 patients in the albuvirtide and NRTI groups,respectively.At 48 weeks,80.4%of patients in the ABT group and 66.0%of those in the NRTI group had HIV-1 RNA levels below 50 copies/mL,meeting the criteria for non-inferiority.For the per-protocol population,the superiority of albuvirtide over NRTI was demonstrated.The frequency of grade 3 to 4 adverse events was similar in the two groups;the most common adverse events were diarrhea,upper respiratory tract infections,and grade 3 to 4 increases in triglyceride concentration.Renal function was significantly more impaired at 12 weeks in the patients of the NRTI group who received tenofovir disoproxil fumarate than in those of the ABT group.Conclusions:The TALENT study is the first phase 3 trial of an injectable long-acting HIV drug.This interim analysis indicates that once-weekly albuvirtide in combination with ritonavir-boosted lopinavir is well tolerated and non-inferior to the WHO-recommended second-line regimen in patients with first-line treatment failure.Trial registration:ClinicalTrials.gov Identifier:NCT02369965;https://www.clinicaltrials.gov.Chinese Clinical Trial Registry No.ChiCTR-TRC-14004276;http://www.chictr.org.cn/enindex.aspx.

Comparison of the anterior and posterior approach in treating four-level cervical spondylotic myelopathy

Background:The optimal surgical approach for four-level cervical spondylotic myelopathy remains controversial.The purpose of this study was to compare clinical and radiological outcomes and complications between the anterior and posterior approaches for four-level cervical spondylotic myelopathy.Methods:A total of 19 patients underwent anterior decompression and fusion and 25 patients underwent posterior laminoplasty and instrumentation in this study.Perioperative information,intraoperative blood loss,clinical and radiological outcomes,and complications were recorded.Japanese Orthopedic Association(JOA)score,36-item short form survey(SF-36)score and cervical alignment were assessed.Results:There were no significant differences in JOA scores between the anterior and posterior group preoperatively(11.6±1.6 vs.12.1±1.5),immediately postoperatively(14.4±1.1 vs.13.8±1.3),or at the last follow-up(14.6±1.0 vs.14.2±1.1)(P>0.05).The JOA scores significantly improved immediately postoperatively and at the last follow-up in both groups compared with their preoperative values.The recovery rate was significantly higher in the anterior group both immediately postoperatively and at the last follow-up.The SF-36 score was significantly higher in the anterior group at the last follow-up compared with the preoperative value(69.4 vs.61.7).Imaging revealed that there was no significant difference in the Cobb angle at C2-C7 between the two groups preoperatively(-2.0°±7.3°vs.-1.4°±7.5°).The Cobb angle significantly improved immediately postoperatively(12.3°±4.2°vs.9.2°±3.6°)and at the last follow-up(12.4°±3.5°vs.9.0°±2.6°)in both groups compared with their preoperative values(P=0.00).Three patients had temporary dysphagia in the anterior group and four patients had persistent axial symptoms in the posterior group.Conclusions:Both the anterior and posterior approaches were effective in treating four-level cervical spondylotic myelopathy in terms of neurological clinical outcomes and radiological features.However,the JOA score recovery rate and SF-36 score in the anterior group were significantly higher.Persistent axial pain could be a major concern when undertaking the posterior approach.

Interferon-α2b spray inhalation did not shorten virus shedding time of SARS-CoV-2 in hospitalized patients: a preliminary matched case-control study

Background:Currently,there are no drugs that have been proven to be effective against severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Because of its broad antiviral activity,interferon(IFN)should be evaluated as a potential therapeutic agent for treatment of coronavirus disease 2019(COVID-19),especially while COVID-19-specific therapies are still under development.Methods:Confirmed COVID-19 patients hospitalized in the First Affiliated Hospital,School of Medicine,Zhejiang University in Hangzhou,China,from January 19 to February 19,2020 were enrolled in a retrospective study.The patients were separated into an IFN group and a control group according to whether they received initial IFN-α2 b inhalation treatment after admission.Propensity-score matching was used to balance the confounding factors.Results:A total of 104 confirmed COVID-19 patients,68 in the IFN group and 36 in the control group,were enrolled.Less hypertension(27.9%vs.55.6%,P=0.006),dyspnea(8.8%vs.25.0%,P=0.025),or diarrhea(4.4%vs.19.4%,P=0.030)was observed in the IFN group.Lower levels of albumin and C-reactive protein and higher level of sodium were observed in the IFN group.Glucocorticoid dosage was lower in the IFN group(median,40 vs.80 mg/d,P=0.025).Compared to the control group,fewer patients in the IFN group were ventilated(13.2%vs.33.3%,P=0.015)and admitted to intensive care unit(ICU)(16.2%vs.44.4%,P=0.002).There were also fewer critical patients in the IFN group(7.4%vs.25.0%,P=0.017)upon admission.Although complications during admission process were comparable between groups,the discharge rate(85.3%vs.66.7%,P=0.027)was higher and the hospitalization time(16 vs.21 d,P=0.015)was shorter in the IFN group.When other confounding factors were not considered,virus shedding time(10 vs.13 d,P=0.014)was also shorter in the IFN group.However,when the influence of other factors was eliminated using propensity score matching,virus shedding time was not significantly shorter than that of the control group(12 vs.15 d,P=0.206).Conclusions:IFN-α2 b spray inhalation did not shorten virus shedding time of SARS-CoV-2 in hospitalized patients.

Comparison of epidemiological and clinical characteristics of COVID-19 patients with and without Wuhan exposure history in Zhejiang Province,China

Background:A novel coronavirus called severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),first identified in Wuhan,China,has been rapidly spreading around the world.This study investigates the epidemiological and clinical characteristics of coronavirus disease 2019(COVID-19)patients in Zhejiang Province who did or did not have a history of Wuhan exposure.Methods:We collected data from medical records of confirmed COVID-19 patients in Zhejiang Province from Jan.17 to Feb.7,2020 and analyzed epidemiological,clinical,and treatment data of those with and without recorded recent exposure in Wuhan.Results:Patients in the control group were older than those in the exposure group((48.19±16.13)years vs.(43.47±13.12)years,P<0.001),and more were over 65 years old(15.95%control vs.5.60%exposure,P<0.001).The rate of clustered onset was also significantly higher in the control group than in the exposure group(31.39%vs.18.66%,P<0.001).The symptom of a sore throat in patients in the exposure group was significantly higher than that in the control group(17.30%vs.10.89%,P=0.01);however,headache in the exposure group was significantly lower than that in the control group(6.87%vs.12.15%,P=0.015).More patients in the exposure group had a significantly lower level of lactate dehydrogenase(LDH)and aspartate aminotransferase(AST)than those in the control group.There was no significant difference in any degree of COVID-19 including mild,severe,and critical between the two groups.Conclusions:From the perspective of epidemiological and clinical characteristics,there was no significant difference between COVID-19 patients with and without Wuhan exposure history.

Clinical characteristics of different subtypes and risk factors for the severity of illness in patients with COVID-19 in Zhejiang, China

Background The outbreak of coronavirus disease 2019(COVID-19)is now becoming an enormous threat to public health.The clinical spectrum of COVID-19 is extensive,of which critical cases are with rapid disease progression and high mortality.The aim of our study is to summarize the characteristics of different subtypes and explore risk factors of illness severity for early identification and prompt treatment.Methods In this retrospective study,we collected data of patients confirmed COVID-19 in Zhejiang Province from 17 January to 12 February 2020.According to the definition of clinical classification,we divided confirmed cases into four types,and summarize epidemiological and clinical characteristics,laboratory and radiograph findings,treatments,and outcomes,respectively.Moreover,we used univariate and multivariate ordinal logistic regression models to explore risk factors for the severity of illness in patients with COVID-19.Results A total of 788 patients were enrolled in our study,of whom 52 cases(6.6%)were mild type,658 cases(83.5%)were common type,61 cases(7.2%)were severe type,and 17 cases(2.2%)were critical type.Multivariate ordinal logistic regression demonstrated increasing odds of the severity of illness in patients with COVID-19 associated with male(odds ratio[OR]=1.7,95%confidence interval[CI]:1.2–2.6 P=0.008),fever(OR=3.6,95%CI:2.1–6.3,P<0.001),cough(OR=1.7,95%CI:1.0–2.9,P=0.041),hemoptysis(OR=3.4,95%CI:1.1–10.3,P=0.032),gastrointestinal symptoms(OR=1.9,95%CI:1.0–3.5,P=0.047),hypertension(OR=2.6,95%CI:1.2–5.6,P=0.013).With the increase of age-grading,risk for the severity of illness was gradually higher(≤18 years[OR=1.0],19–40 years[OR=12.7,95%CI:4.5–36.0,P<0.001],41–65 years[OR=14.8,95%CI:5.2–42.1,P<0.001],≥66 years[OR=56.5,95%CI:17.1–186.5,P<0.001]).Conclusions Clinicians should pay close attention to these features in patients with COVID-19 including older age,male,fever,cough,hemoptysis,gastrointestinal symptoms and hypertension to identify the severity of illness as early as possible.

Drawing-upsetting-extrusion-clinching of high-strength steel and aluminum alloy

To realize good point connection between high-strength steel and aluminum alloy,a process of drawing-upsetting-extrusion-clinching was proposed.First,the sheets were drawn;then,the bottom of the protrusion part was extruded,forming the necessary initial interlock;and finally,the protrusion part was reverse press clinched,forming a certain height of the clinched head.Taking DP980 high-strength steel and A15083 aluminum alloy as the connection objects and using the method of numerical simulation combined with experimental test,the mold was made,and the experiment was carried out on the basis of numerical simulation.The experimental results proved the feasibility of the process and the effectiveness of the numerical model.The simulation and experimental results show that the necessary interlock in the drawing-upsetting-extrusion stage is the premise of effective connection.The relative protrusion height should be around 55.6%after reverse-press-clinching.The best comprehensive mechanical properties measured by strength test were shear resistance of 2644 N,fatigue life of 24,535 times and peel resistance of 1522 N.Through failure analysis,the relationship between the interlock Tu and the neck thickness Tn of the joint with the best comprehensive mechanical properties was established as Tu=0.35Tn.The design method of die and process parameters when the sheet thickness changes was researched by numerical simulation.The results show that the clearance between the punch and the die and the bottom thickness are directly proportional to the sheet thickness,and the drawing depth is directly proportional to the punch radius.