前部转动导叶可调涡轮泄漏与激波特性研究

可调涡轮导叶与蜗壳存在端壁间隙,在大膨胀比导叶小开度时,产生的强间隙泄漏流使涡轮效率大幅降低。为抑制导叶尾缘区域的间隙泄漏流量,提出了一种前部转动导叶,并将其数值计算结果和原始模型进行了比对。结果表明:小开度下,前部转动导叶可有效抑制间隙泄漏流量,涡轮性能提升了13个百分点;而随着导叶开度的增大,泄漏占涡轮总损失程度降低,前部转动导叶带来的效率收益也随之减小。在可调涡轮中间开度下,前部转动导叶可通过增加转/静间距而使激波强度弱化,并降低因激波和泄漏流所引发的转静干涉强度,从而提升涡轮叶片的可靠性。

Transition-Metal-Free Allylic Defluorination Cross-Electrophile Coupling Employing Rongalite

Comprehensive Summary The conversion of CF3-alkenes to gem-difluoroalkenes using reductive cross-coupling strategy has received much attention in recent years,however,the use of green and readily available reducing salt to mediate these reactions remains to be explored.In this work,a concise construction of gem-difluoroalkenes,which requires neither a catalyst nor a metal reducing agent,was established.Rongalite,a safe and inexpensive industrial product,was employed as both a radical initiator and reductant.This procedure was compatible with both linear and cyclic diaryliodonium salts,enabling a wide variety of substrates(>70 examples).The utility of this approach was demonstrated through gram-scale synthesis and efficient late-stage functionalizations of anti-inflammatory drugs.

Rongalite as a Versatile Reagent in Organic Synthesis

This review provides a comprehensive summary of progress to date in the utilization of rongalite as a versatile reagent in organic synthesis,with a focus on recent researches.The contents have been organized according to the functions exhibited by rongalite.Reaction mechanisms are provided,demonstrating the multifaceted roles of this compound in various transformations,including as a sulfone,C1 or masked proton source and as a single electron donor or reducing agent.

Rapid identification of chronic kidney disease in electronic health record database using computable phenotype combining a common data model

To the Editor:Chronic kidney disease(CKD)is a global burden of the public health.The global prevalence of CKD exceeded 10%while the awareness was around 10%.[1]In the era of big data,improving the identification of CKD using informatic tools is important.Computable phenotype is proven as an efficient tool to facilitate the process of patient identification using electronic health record(EHR)data.

Renin--angiotensin system inhibitor is associated with the reduced risk of all-cause mortality in COVID-19 among patients with/without hypertension

Consecutively hospitalized patients with confirmed coronavirus disease 2019(COVID-19)in Wuhan,China were retrospectively enrolled from January 2020 to March 2020 to investigate the association between the use of renin–angiotensin system inhibitor(RAS-I)and the outcome of this disease.Associations between the use of RAS-I(angiotensin-converting enzyme inhibitor(ACEI)or angiotensin receptor blocker(ARB)),ACEI,and ARB and in-hospital mortality were analyzed using multivariate Cox proportional hazards regression models in overall and subgroup of hypertension status.A total of 2771 patients with COVID-19 were included,with moderate and severe cases accounting for 45.0%and 36.5%,respectively.A total of 195(7.0%)patients died.RAS-I(hazard ratio(HR)=0.499,95%confidence interval(CI)0.325–0.767)and ARB(HR=0.410,95%CI 0.240–0.700)use was associated with a reduced risk of all-cause mortality among patients with COVID-19.For patients with hypertension,RAS-I and ARB applications were also associated with a reduced risk of mortality with HR of 0.352(95%CI 0.162–0.764)and 0.279(95%CI 0.115–0.677),respectively.RAS-I exhibited protective effects on the survival outcome of COVID-19.ARB use was associated with a reduced risk of all-cause mortality among patients with COVID-19.

Phase transition of the frustrated antiferromagntic J1-J2-J3 spin-1/2 Heisenberg model on a simple cubic lattice

We have comprehensively investigated the frustrated J1-J2-J3 Heisenberg model on a simple cubic lattice. This model allows three regimes of magnetic order, viz., (π;π;π), (0;π;π) and (0;0;π), denoted as AF1, AF2, and AF3, respectively. The effects of the interplay of neighboring couplings on the model are studied in the entire temperature range. The zero temperature magnetic properties of this model are discussed utilizing the linear spin wave (LSW) theory, nonlinear spin wave (NLSW) theory, and Green’s function (GF) method. The zero temperature phase diagrams evaluated by the LSW and NLSW methods are illustrated, and are observed to exhibit different parameter boundaries. In certain regions and along the parameter boundaries, the possible phase transformations driven by the parameters are discussed. The results obtained using the LSW, NLSW, and GF methods are compared with those obtained using the series expansion (SE) method, and are observed to be in good agreement when the value of J2 is not close to the parameter boundaries. The ground state energies obtained using the LSW and NLSW methods are close to that obtained using the SE method. At finite temperatures, only the GF method is employed to evaluate the magnetic properties, and the calculated phase diagram is observed to be identical to the classical phase diagram. The results indicate that at the parameter boundaries, a temperature-driven first-order phase transition between AF1 and AF2 may occur along the boundary line. Along the AF1-AF3 and AF2-AF3 boundary lines, AF3 is less stable than AF1 and AF2. Our calculated critical temperature agrees with that obtained using Monte Carlo simulations and pseudofermion functional renormalization group scheme.