基于动态再结晶软化理论的Ti-22Al-25Nb合金新型本构关系模型

依据热压烧结制备Ti-22Al-25Nb合金热模拟压缩所得实验数据,研究合金在热变形温度为975～1075°C、应变速率为0.001～1s^(-1)条件下的热变形行为。通过对数据的分析,建立包含Z参数模型、动态再结晶临界模型与动态再结晶动力学模型的新型本构关系模型。实验结果表明:Ti-22Al-25Nb合金的热变形激活能为410.172 kJ/mol,且临界应变与峰值应变之间的比值为0.67。此外,所建立的本构关系模型的预测值在应变速率为0.1 s^(-1)、应变量小于0.1条件下与实验值相差较大,但整体上流动应力水平预测值与实验值吻合较好。并采用EBSD技术对动态再结晶动力学模型的预测精度进行分析。

热变形条件下V-10Cr-5Ti合金动态再结晶行为的元胞自动机模拟（英文）

通过在Gleeble-1500热模拟压缩机上对V-10Cr-5Ti合金进行温度为950～1350℃、应变速率为0.01～10 s^(-1)的热模拟压缩实验,并基于Arrhenius模型、位错密度模型、形核模型和晶粒长大模型,建立一种元胞自动机(CA)模型来模拟和表征动态再结晶过程中的组织演变。结果表明:流动应力对变形速率和变形温度具有强烈的依赖性,利用Arrhenius模型预测的应力值与实际测量值的误差小于8%。CA模型计算得到的初始平均晶粒尺寸为86.25μm,与试验测量得到的85.63μm相近。模拟表明:初始晶粒尺寸对动态再结晶组织演化影响并不显著,而提高应变速率或降低变形温度均可细化再结晶晶粒。

Efficacy and safety of fondaparinux versus enoxaparin in patients undergoing percutaneous coronary intervention treated with the glycoprotein IIb/IIIa inhibitor tirofiban

Background: In worldwide, the mortality rate of acute myocardial infarction(AMI) raises year by year. Although the applications of percutaneous coronary intervention(PCI) and anticoagulants effectively reduce the mortality of patients with acute coronary syndrome(ACS), but also increase the incidence of bleeding. Therefore, drugs with stable anticoagulant effects are urgently required.Methods: We enrolled 894 patients with acute coronary syndrome who underwent percutaneous coronary intervention in Shenyang Northern Hospital from February 2010 to May 2012; 430 patients were included in the fondaparinux group(2.5mg/d), and 464 were included in the enoxaparin group(1mg/kg twice daily). Fondaparinux and enoxaparin were applied for 3–7 days. All patients were treated with tirofiban [10μg/kg for 3min initially and 0.15μg/(kg·min) for 1 to 3 days thereafter]. The primary efficacy endpoint was the incidence of a major adverse cerebrovascular or cardiovascular event. The primary safety endpoint was bleeding within 30 days and 1 year after percutaneous coronary intervention.Results: One-year data were available for 422 patients in the fondaparinux group and for 453 in the enoxaparin group. The incidence of a major adverse cerebrovascular or cardiovascular event(10.9% vs 12.6%, P=0.433) and cardiac mortality(0.5% vs 1.5%, P=0.116) were generally lower in the fondaparinux group than in the enoxaparin group, although the differences were not significant. Compared with the enoxaparin group, the fondaparinux group had a significantly decreased rate of bleeding at 30 days(0.9% vs 2.9%, P=0.040) and 1 year(2.4% vs 5.5%, P=0.018). In addition, the rate of major bleeding events was lower in the fondaparinux group, but this difference was not significant(0.2% vs 0.9%, 0.2% vs 1.1%).Conclusion: In tirofiban-treated patients with acute coronary syndrome undergoing percutaneous coronary intervention, fondaparinux presented similar efficacy for ischemia events as enoxaparin. However, fondaparinux significantly decreased the incidence of bleeding, thus providing safer anticoagulation therapy.

Predictors of contrast-induced acute kidney injury in patients with coronary artery disease receiving contrast agents twice within 30 days

Background:None of study mentioned about contrast-induced acute kidney injury(CI-AKI)in people who have received contrast agents twice within in a short period of time.This study is trying to identify the predictors.Methods:We enrolled 607 patients between Oct.2010 and Jul.2015 who received contrast agents twice within 30 days in the Department of Cardiology of the General Hospital of Shenyang Military Region.The primary outcome was CI-AKI within 72 h after contrast agent exposure.Patients were divided into groups A(n=559)and group B(n=48)according to whether CI-AKI occurred after the second agent.Results:Patients in group B(CI-AKI occurred after the second agent)had a more rapid heart rate and more usage of diuretics and digitalis.In group B,CI-AKI occurred more frequently after the first agent.Multivariate logistic regression showed that diuretic(P=0.006)and intra-aortic balloon pump(IABP)usage(P=0.012)were independent predictors of CI-AKI after the first agent.Angiotensin-converting enzyme inhibitor/AngiotensinⅡreceptor antagonist(ACEI/ARB)usage(P=0.039),IABP usage(P=0.040)and CI-AKI occurring after administration of the first agent(P=0.015)were independent predictors of CI-AKI after the second.Furthermore,dividing the patients into tertiles of the time interval between the two agents showed that CI-AKI occurred more frequently when the second agent was administered within 1–3 days after the first exposure than within 4–6 days(12.4%vs.5.0%,P=0.008)or≥7 days(12.4%vs.6.4%,P=0.039).Conclusions:Diuretic and IABP usage are independent predictors of CI-AKI following exposure to a first contrast agent.The major predictors of CI-AKI after exposure to a second agent are time since the first contrast exposure,ACEI/ARB usage,and IABP usage.More importantly,a three-day interval between the two agents is associated with a higher incidence of CI-AKI following the second administration.

Effect of pine wood nematode invasion on pine community functions in the Pinghu region, Zhejiang Province, eastern China

In order to investigate the effect of invastion by pine wood nematode(PWN), this study analyzed several functional indices, i.e., the increment in DBH and stand volume and biomass, in the damaged stands with various mixed percentages of Pinus massoniana and P. thunbergii and with different levels of damage. According to the results of rate of change in increment of DBH and stand volume, the forest ecosystem resistance against PWN increased with a reduction in the mixed ratio of pine. The resistance was highest with a mixed percentage of 50%. The invasion of PWN changed the corresponding relationship of increment between DBH and stand volume(pure stands > 7:3 conifer and broadleaf > 6:4 conifer and broadleaf > 5:5 conifer and broadleaf) among the P. thunbergii stands when there is no damage, but for P. massoniana stands this phenomenon did not occur. For the increment rate of DBH and stand volume, this significant change in P. thunbergii forest indicates that the resistance of pure P. thunbergii forest was higher than that of P. massoniana. The invasion of PWN accelerates the succession from pure stands to mixed stands and then to the broadleaf evergreen stands.

Cradle for the newborn Monochamus saltuarius:Microbial associates to ward off entomopathogens and disarm plant defense

The Japanese pine sawyer,Monochamus saltuarius,as a beetle vector of Bur-saphelenchus xylophilus(pine wood nematode),is an economically important forest pest in Eurasia.To feed on the phloem and xylem of conifers,M.saltuarius needs to overcome various stress factors,including coping with entomopathogenic bacteria and also various plant secondary compounds(PSCs).As an important adaptation strategy to colonize host trees,M.saltuarius deposit eggs in oviposition pits to shield their progeny.These pits har-bor bacterial communities that are involved in the host adaptation of M.saltuarius to the conifers.However,the composition,origin,and functions of these oviposition pit bacteria are rarely understood.In this study,we investigated the bacterial community associated with M.saltuarius oviposition pits and their ability to degrade PSCs.Results showed that the bacterial community structure of M.saltuarius oviposition pits significantly differed from that of uninfected phloem.Also,the oviposition pit bacteria were predicted to be enriched in PSC degradation pathways.The microbial community also harbored a lethal strain of Serratia,which was significantly inhibited.Meanwhile,metatranscriptome anal-ysis indicated that genes involved in PSCs degradation were expressed complementarily among the microbial communities of oviposition pits and secretions.In vitro degrada-tion showed that bacteria cultured from oviposition pits degraded more monoterpenes and flavonoids than bacteria cultured from uninfected phloem isolates.Disinfection of ovipo-sition pits increased the mortality of newly hatched larvae and resulted in a significant decrease in body weight in the early stages.Overall,our results reveal that M.saltuarius construct oviposition pits that harbor a diverse microbial community,with stronger PSCs degradation abilities and a low abundance of entomopathogenic bacteria,resulting in the increased fitness of newly hatched larvae.

工厂化上海青流水线收割装置的设计与试验

针对工厂化种植的叶菜在收获工序中机械化水平不高、劳动强度大、耗时长、效率低等问题,以具代表性的上海青为研究对象,设计了一款以带锯切割、螺杆张紧和V型皮带传动的上海青流水线生产收割装置。基于上海青根茎切割过程的理论研究和仿真分析,确定了影响切割效果的主要因素,并试制试验样机进行正交试验,获得较优参数组合如下:带锯为光刃带锯,进给速度为0.05 m/s,切割转速为400 r/min。进行了验证试验,结果表明:切割效果好,端面平整,合格率达到88.9%,收割装置达到了高效省力的设计要求。该研究可为叶菜流水线生产中的收割设备研发提供参考。

Identification of a novel coronavirus causing severe pneumonia in human:a descriptive study

Background:Human infections with zoonotic coronaviruses(CoVs),including severe acute respiratory syndrome(SARS)-CoV and Middle East respiratory syndrome(MERS)-CoV,have raised great public health concern globally.Here,we report a novel batorigin CoV causing severe and fatal pneumonia in humans.Methods:We collected clinical data and bronchoalveolar lavage(BAL)specimens from five patients with severe pneumonia from Wuhan Jinyintan Hospital,Hubei province,China.Nucleic acids of the BAL were extracted and subjected to next-generation sequencing.Virus isolation was carried out,and maximum-likelihood phylogenetic trees were constructed.Results:Five patients hospitalized from December 18 to December 29,2019 presented with fever,cough,and dyspnea accompanied by complications of acute respiratory distress syndrome.Chest radiography revealed diffuse opacities and consolidation.One of these patients died.Sequence results revealed the presence of a previously unknownβ-CoV strain in all five patients,with 99.8%to 99.9%nucleotide identities among the isolates.These isolates showed 79.0%nucleotide identity with the sequence of SARS-CoV(GenBank NC_004718)and 51.8%identity with the sequence of MERS-CoV(GenBank NC_019843).The virus is phylogenetically closest to a bat SARS-like CoV(SL-ZC45,GenBank MG772933)with 87.6%to 87.7%nucleotide identity,but is in a separate clade.Moreover,these viruses have a single intact open reading frame gene 8,as a further indicator of bat-origin CoVs.However,the amino acid sequence of the tentative receptor-binding domain resembles that of SARS-CoV,indicating that these viruses might use the same receptor.Conclusion:A novel bat-borne CoV was identified that is associated with severe and fatal respiratory disease in humans.

Natural History of Seroma Following the Immediate Latissimus Dorsi Flap Method of Breast Reconstruction

Background： The latissimus dorsi （LD） flap procedure remains a popular and useful breast reconstrtlction tool in China and Western countries, and donor site seroma formation is the main complication. This study was conducted in Chinese patients to determine whether stable cases of seromas would resolve without treatment. Methods： A retrospective review of 45 consecutive cases of immediate breast reconstruction with LD flap from April 2012 to February 2017 was conducted. The scope of the seroma was demarcated with a marker pen, and cases that remained stable over time （i.e. the size of the seroma did not increase） were observed without treatment. The measured outcomes included the incidence ofseromas, the volume and duration of postoperative wound drainage, and other demographic characteristics. Results： Twenty-four patients （53.3%） developed a seroma at the donor site. Of these, 21 patients （87.5%） did not require treatment, and the seroma resolved over time. The mean duration of a sustained serol-na was 6.8 ± 1.4 weeks （range： 4-9 weeks）. Conclusions： This study observed the scope and progression of the seromas and found that seromas at the LD donor sites resolved over time without treatnlent.

Online Scheduling on Two Uniform Unbounded Parallel-Batch Machines to Minimize Makespan

We study an online(over time)scheduling problem on two uniform unbounded parallel-batch machines with processing speed 1 and v(0<≤1),respectively,to minimize the makespan.We first show that no online algorithm can have a competitive ratio less than 1+αL,whereαL=(√5−1)/2≈0.618 if 0≤1/2,andαL=α2(v)is the positive root ofα^(3)+3α^(2)+(3−1/v)α−1/v=0 if1/2≤1.This lower bound is still valid when all jobs have the same processing times.Then,we provide an online algorithm with a competitive ratio at most min{(√5+1)/2,√2/v}.When the jobs have the same processing times,we present the best possible online algorithm with a competitive ratio 1+αL.