Lower bound on the spread of valley splitting in Si/SiGe quantum wells induced by atomic rearrangement at the interface

The achievement of universal quantum computing critically relies on scalability.However,ensuring the necessary uniformity for scalable silicon electron spin qubits poses a significant challenge due to the considerable fluctuations in valley splitting energy(E_(VS))across quantum dot arrays,which impede the initialization of qubit systems comprising multiple spins and give rise to spin–valley entanglement resulting in the loss of spin information.These E_(VS)fluctuations have been attributed to variations in the in-plane averaged alloy concentration along the confinement direction of Si/SiGe quantum wells.In this study,employing atomistic pseudopotential calculations,we unveil a significant spectrum of E_(VS)even in the absence of such concentration fluctuations.This spectrum represents the lower limit of the wide range of E_(VS)observed in numerous Si/SiGe quantum devices.By constructing simplified interface atomic step models,we analytically demonstrate that the lower bound of the E_(VS)spread originates from the in-plane random distribution of Si and Ge atoms within SiGe barriers——an inherent characteristic that has been previously overlooked.Additionally,we propose an interface engineering approach to mitigate the in-plane randomness-induced fluctuations in E_(VS)by inserting a few monolayers of pure Ge barrier at the Si/SiGe interface.Our findings provide valuable insights into the critical role of in-plane randomness in determining E_(VS)in Si/SiGe quantum devices and offer reliable methods to enhance the feasibility of scalable Si-based spin qubits.

腹腔镜直肠癌根治术治疗直肠癌的效果及对血清疼痛因子、miR-103、miR-21与肛肠动力学指标的影响

目的探讨腹腔镜直肠癌根治术治疗直肠癌的效果及对血清疼痛因子、miR-103、miR-21和肛肠动力学指标的影响。方法选取2017年9月-2019年12月该院直肠癌患者93例进行前瞻性随机对照研究,简单随机化法分为观察组(n=46)和对照组(n=47)。观察组采取腹腔镜直肠癌根治术,对照组行传统开腹手术。比较两组手术情况、并发症发生率、术前、术后1 d、术后3 d血清疼痛因子[神经肽Y(NPY)、前列腺素E_(2)(PGE_(2))、神经生长因子(NGF)]、术前、术后1周、术后2周miR-103、miR-21水平和术前、术后4周、术后8周肛肠动力学指标[肛管最长收缩时间(ALCT)、肛管最大收缩压(AMCP)、直肠静息压(RRP)]水平。结果两组患者手术时间和淋巴结清扫数目比较,差异均无统计学意义(P>0.05);观察组术中出血量少于对照组,肛门排气时间、进食时间和住院时间均较对照组短(P<0.05);两组患者术后1和3 d血清NPY、PGE2和NGF水平均较术前提高,但观察组低于对照组(P<0.05);两组患者术后1和2周血清miR-103和miR-21较术前降低,且观察组低于对照组(P<0.05);两组患者术后4和8周ALCT、AMCP和RRP水平较术前降低,但观察组高于对照组(P<0.05)。结论腹腔镜直肠癌根治术应用于直肠癌患者,能有效减少术中出血量,缩短患者术后恢复时间,且抑制疼痛因子表达,调节血清miR-103和miR-21水平,促进患者肛肠动力学恢复。

Tissue elasticity displayed by elastography and its correlation with the characteristics of collagen type I and type III in prostatic stroma

We investigated the prostate elasticity displayed by elastography and its correlation with the content and distribution of collagen type I （Col1） and type III （Col3）. A total of 62 patients underwent transrectal real-time tissue elastography （TRTE） examinations, Targeted biopsies were performed after 12-core systematic biopsy, The tissues corresponding to the elastograms were stained with picric acid-sirius red. The distribution of Col I and type Col3 was observed, and the collagen volume fraction （CVF） of these two types of collagen fibers was calculated, The CVFs of Coll in the stiff and soft groups were 0.05 ± 0.02 and 0.02 ± 0.01 {P= 0.002）, respectively. The CVFs of Col3 in the stiff and soft groups were 0.05 ± 0.04 and 0.07 ± 0,03 （P= 0,13）, respectively, The circular analysis results showed that collagen fibers were disorganized both in the soft and stiff groups, Coll and Col3 were mainly cross-linked, and some parallelization was observed in the sections. The distributions of Coll and Col3 were different between the stiff and soft groups （P = 0,03）, In conclusion, the texture of the prostate is due to the content of Coll and its relative correlation with Col3.

Atomic-Ordering-Induced Quantum Phase Transition between Topological Crystalline Insulator and Z_2 Topological Insulator

Topological phase transition in a single material usually refers to transitions between a trivial band insulator and a topological Dirac phase, and the transition may also occur between different classes of topological Dirac phases.It is a fundamental challenge to realize quantum transition between Z_2 nontrivial topological insulator（TI） and topological crystalline insulator（TCI） in one material because Z_2 TI and TCI have different requirements on the number of band inversions. The Z_2 TIs must have an odd number of band inversions over all the time-reversal invariant momenta, whereas the newly discovered TCIs, as a distinct class of the topological Dirac materials protected by the underlying crystalline symmetry, owns an even number of band inversions. Taking PbSnTe_2 alloy as an example, here we demonstrate that the atomic-ordering is an effective way to tune the symmetry of the alloy so that we can electrically switch between TCI phase and Z_2 TI phase in a single material. Our results suggest that the atomic-ordering provides a new platform towards the realization of reversibly switching between different topological phases to explore novel applications.

Persistence and clearance of viral RNA in 2019 novel coronavirus disease rehabilitation patients

Background:A patient’s infectivity is determined by the presence of the virus in different body fluids,secretions,and excreta.The persistence and clearance of viral RNA from different specimens of patients with 2019 novel coronavirus disease(COVID-19)remain unclear.This study analyzed the clearance time and factors influencing 2019 novel coronavirus(2019-nCoV)RNA in different samples from patients with COVID-19,providing further evidence to improve the management of patients during convalescence.Methods:The clinical data and laboratory test results of convalescent patients with COVID-19 who were admitted to from January 20,2020 to February 10,2020 were collected retrospectively.The reverse transcription polymerase chain reaction(RT-PCR)results for patients’oropharyngeal swab,stool,urine,and serum samples were collected and analyzed.Convalescent patients refer to recovered non-febrile patients without respiratory symptoms who had two successive(minimum 24 h sampling interval)negative RT-PCR results for viral RNA from oropharyngeal swabs.The effects of cluster of differentiation 4(CD4)+T lymphocytes,inflammatory indicators,and glucocorticoid treatment on viral nucleic acid clearance were analyzed.Results:In the 292 confirmed cases,66 patients recovered after treatment and were included in our study.In total,28(42.4%)women and 38 men(57.6%)with a median age of 44.0(34.0-62.0)years were analyzed.After in-hospital treatment,patients’inflammatory indicators decreased with improved clinical condition.The median time from the onset of symptoms to first negative RT-PCR results for oropharyngeal swabs in convalescent patients was 9.5(6.0-11.0)days.By February 10,2020,11 convalescent patients(16.7%)still tested positive for viral RNA from stool specimens and the other 55 patients’stool specimens were negative for 2019-nCoV following a median duration of 11.0(9.0-16.0)days after symptom onset.Among these 55 patients,43 had a longer duration until stool specimens were negative for viral RNA than for throat swabs,with a median delay of 2.0(1.0-4.0)days.Results for only four(6.9%)urine samples were positive for viral nucleic acid out of 58 cases;viral RNA was still present in three patients’urine specimens after throat swabs were negative.Using a multiple linear regression model(F=2.669,P=0.044,and adjusted R2=0.122),the analysis showed that the CD4+T lymphocyte count may help predict the duration of viral RNA detection in patients’stools(t=-2.699,P=0.010).The duration of viral RNA detection from oropharyngeal swabs and fecal samples in the glucocorticoid treatment group was longer than that in the non-glucocorticoid treatment group(15 days vs.8.0 days,respectively;t=2.550,P=0.013)and the duration of viral RNA detection in fecal samples in the glucocorticoid treatment group was longer than that in the non-glucocorticoid treatment group(20 days vs.11 days,respectively;t=4.631,P<0.001).There was no statistically significant difference in inflammatory indicators between patients with positive fecal viral RNA test results and those with negative results(P>0.05).Conclusions:In brief,as the clearance of viral RNA in patients’stools was delayed compared to that in oropharyngeal swabs,it is important to identify viral RNA in feces during convalescence.Because of the delayed clearance of viral RNA in the glucocorticoid treatment group,glucocorticoids are not recommended in the treatment of COVID-19,especially for mild disease.The duration of RNA detection may relate to host cell immunity.

Constitutive Modeling for Flow Behaviors of Superaustenitic Stainless Steel S32654 during Hot Deformation

Hot deformation behavior of superaustenitic stainless steel S32654 was investigated with hot compression tests at temperatures of 950-1250 C and strain rates of 0. 001-10 s-1. Above 1150 ℃, with strain rate lower than 0.1 s -1 , the flow curves exhibit nearly steady state behavior, while at higher strain rate, continuous flow softening occurs. To provide a precise prediction of flow behavior for the alloy, the constitutive modeling considering effect of strain was derived on the basis of the obtained experimental data and constitutive relationship which incorporated Ar- rhenius term and hyperbolic sine type equation. The material constants α, n, Q and lnA are found to be functions of the strain and can be fitted employing eighth-order polynomial. The developed constitutive model can be employed to describe the deformation behavior of superaustenitic stainless steel S32654.

Effect of Precipitation on Hot Deformation Behavior and Processing Maps of Nickel-Base UNS N10276 Alloy

The hot deformation characteristics and processing maps of aged nickel-base UNS N10276 alloy were inves- tigated and compared with those of solution-treated UNS N10276 alloy at temperatures of 950-1250 ℃ and strain rates between 0.01 and 10 s-1. The dominant precipitated phase in the aged alloy was identified as topologically close-packed （TCP） # phase enriched in Mo and Ni. The precipitates present in the UNS N10276 alloy could significantly facilitate flow softening after peak stress at temperatures lower than 1150 ℃ and strain rates higher than 0.01 s-1. Processing maps at true strains of 0.1-0.9 were developed using the dynamic materials model and experimental flow stress data. Although aging treatment slightly shrank the suitable hot working window of this alloy, the aged alloy showed higher peak efficiencies of power dissipation and smaller unstable regions in comparison with solution-treated alloy. Furthermore, aging treatment eliminated the instability region of processing maps at true strains of 0.2-0.5. The precipitated phase promoted dynamic recrystallization （DRX） by the particle-stimulated nucleation （PSN） mechanism, which resulted in the larger fraction of DRX as well as finer and more uniform grain structure in the aged alloy specimens compared to the solution-treated alloy.

Grain Growth Behavior of Inconel 625 Superalloy

The grain growth（GG）behavior of Inconel 625 superalloy was studied in the temperature range of 900-1 250 ℃and holding time range of 10-80 min.Microstructures of the alloy were characterized by optical metallography,scanning electron microscopy（SEM）and transmission electron microscopy（TEM）.Grains grew obviously with either increasing temperature or extending holding time at temperatures above 1 050℃.However,at temperatures lower than 1 050 ℃,the GG was sluggish due to the pinning effect of carbide particles on grain boundary（GB）.Threshold temperature for transition from mixed grain structure to uniform one was considered to be around 1 100℃.Once the temperatures surpassed 1 200℃,an instant increase in the grain size occurred showing no dependence on holding time.TEM analysis showed that the dominant second phase formed heterogeneously on the GB was M6 C,which significantly impeded grain growth.On the basis of experimental data,the mathematical model of GG was established,which can describe GG behavior of Inconel 625 alloy during solution treatment（ST）at 1 100-1 250 ℃.The activation energy for GG of Inconel 625 alloy was 207.3kJ,which suggested that the GG of Inconel 625 alloy was controlled by the process of GB diffusion.

Identifying the Risk of SARS-CoV-2 Infection and Environmental Monitoring in Airborne Infectious Isolation Rooms(AIIRs)

Healthcare workers(HCWs)are at high risk of occupational exposure to the new pandemic human coronavirus,SARSCoV-2,and are a source of nosocomial transmission in airborne infectious isolation rooms(AIIRs).Here,we performed comprehensive environmental contamination surveillance to evaluate the risk of viral transmission in AIIRs with 115 rooms in three buildings at the Shanghai Public Health Clinical Center,Shanghai,during the treatment of 334 patients infected with SARS-CoV-2.The results showed that the risk of airborne transmission of SARS-CoV-2 in AIIRs was low(1.62%,25/1544)due to the directional airflow and strong environmental hygiene procedures.However,we detected viral RNA on the surface of foot-operated openers and bathroom sinks in AIIRs(viral load:55.00–3154.50 copies/mL).This might be a source of contamination to connecting corridors and object surfaces through the footwear and gloves used by HCWs.The risk of infection was eliminated by the use of disposable footwear covers and the application of more effective environmental and personal hygiene measures.With the help of effective infection control procedures,none of 290 HCWs was infected when working in the AIIRs at this hospital.This study has provided information pertinent for infection control in AIIRs during the treatment of COVID-19 patients.

Morphologies of secondary austenite in 2507 duplex stainless steel after heat treatment

The microstructure evolution of secondary austenite in 2507 duplex stainless steel was investigated by means of optical metallography,scanning electron microscopy and confocal scanning laser microscopy.Four types of secondary austenite(γ2)morphologies including partially transformed austenite,grain boundary austenite,Widmannstätten austenite(WA)and intragranular austenite could be formed during cooling after solution treatment.It was concluded that secondary austenite morphology was mainly dependent on cooling rates.Two mechanisms of WA formation were proposed.WA nucleated at grain boundary of ferrite or at the formed phase boundary.Transmission electron microscopy(TEM)analysis displayed that WA grew in parallel to the ferrite.The effects of Cr_(2)N on secondary austenite precipitation were discussed in detail.Once Cr_(2)N was involved,a mechanism was proposed that secondary austenite formed by element diffusion,leading to the migration of the austenite–ferrite interface.Cr_(2)N acted as the nucleation sites forγ2 and provided the nitrogen for the transformation;meanwhile,the precipitation of Cr_(2)N during the rapid cooling was captured by TEM.A process of nucleation followed by diffusion was concluded to be the formation of secondary austenite with no Cr_(2)N precipitated.The decomposition of secondary austenite was also studied,which was found to be a diffusion mechanism followed by displacement in connection with the element distribution.

Development of Chinese duplex stainless steel in recent years

The development in research, production, applications, and national standards of Chinese duplex stainless steel （DSS） in recent years was introduced in light of the worldwide development in the field of DSS. The results showed that the output of Chinese DSS increased greatly, and at the same time its grade gradually evolved into a collaborative developing series including the main grade type 2205 and other DSS types in recent years. Economical DSS and super DSS underwent rapid development, especially after 2010. In re- cent years, the application of Chinese DSS has been expanded further not only in traditional application ar- eas such as the petrochemical industry, but also in diverse new fields such as oil and gas transportation, chemical tanker manufacturing, nuclear power plants, and construction. Moreover, due to the increase in output and improvement in quality, as well as applications in Chinese projects, Chinese DSS has also been exported to the Middle East, Eastern Europe, and other regions.

Effects of Carbon Content on Mechanical Properties of Inconel 718 Alloy

For improving the service performance of Inconel 718 alloy, especially used as a corrosion-resistant alloy for special environment, the microstructure and mechanical property of different carbon-containing Inconel 718 alloys were investigated by the Thermo-Calc software and experiments. The experimental results indicated that the mor- phology, distribution and types of carbides mainly existing in the form of MC＇were hardly influenced by solution treatment at 1050 ℃ for 1 h. The precipitation amount and particle size of carbides decreased with the decrease of carbon content, which was the main reason resulting in the increase of ductility and toughness. In addition, moving dislocation could be restrained by the precipitation of carbides. Therefore, the strength could benefit from the precip- itation strengthening of carbides when the precipitation of γ′/γ″ phase was not influenced by the precipitation of carbides.

Optimization of Hot Workability in Superaustenitic Stainless Steel 654SMO

Hot compression tests were conducted on a Gleeble-3800 machine in a temperature range of 950 to 1200 ℃ and a strain rate range of 0. 001 to 10 s-1 in order to study the hot deformation behaviour of superaustenitic stainless steel 654SMO. The results show that peak stress increases with decreasing temperature and increasing strain rate, and the apparent activation energy of this alloy was determined to be about 494 kJ/mol. The constitutive equation which can be used to relate the peak stress to the absolute temperature and strain rate was obtained. The processing maps for hot working developed on the basis of flow stress data and the dynamic materials model were adopted to op- timize the hot workability. It is found that the features of the maps obtained in the strain range of 0.2 to 1.0 are fun- damentally similar, indicating that the strain does not have a substantial influence on processing map. The combina- tion of processing map and mierostructural observations indicates that the favorable hot deformation conditions are located in two domains of processing map. The first domain occurs in the temperature range of 980 to 1035 ℃ and strain rate range of 0. 001 to 0.01 s-1 with a peak efficiency of 55%. The second domain appears in the temperature range of 1 120 to 1 180 ℃ and strain rate range of 0.3 to 3 s-1 with peak efficiency of 35%. Compared to other stable domains, the specimens deformed in these two domains exhibit full dynamic recrystallization grains with finer and more uniform sizes. An instability domain occurs at temperatures below 1 100 ℃ and strain rate above 0.1 s-1 , and flow instability is manifested in the form of flow localization.

Precipitated phases of superaustenitic stainless steel 654SMO

The phase diagram of superaustenitic stainless steel 654SMO was calculated by thermodynamic software and the precipitated phases in the specimens aged at 800-1100°C for 1hwere studied by methods of physicochemical phase analysis,scanning electron microscopy and transmission electron microscopy.The results showed that the size of precipitated particles increased with increasing the temperature.The amount of second phases reached the maximum value at 900°C,but decreased above 900°C.There were about eight kinds of precipitated phases in 654SMO includingσphase,Cr_2N,μphase,χphase,Laves phase,M_（23）C_6,M_6C and M_3C,in which theσphase and Cr_2N were the dominant precipitated phases.

Strain-induced Precipitation Behavior ofδPhase in Inconel 718 Alloy

To study the precipitation dynamics of 3 phase in Inconel 718 alloy, two-stage interrupted compression method was used in the region of cold deformation temperatures and the temperatures range from 875 to 975 ℃. The precipitation-time-temperature （PTT） curve of 3 phase was obtained by analyzing the softening kinetics curves. For verifying the type of the precipitates and confirming the validity of the test, the transmission electron microscopy （TEM）, scanning transmission electron microscopy （STEM） and energy dispersion spectrum （EDS） were em- ployed. Experimental results indicated that the PTT curve for 3 precipitation exhibited a typical ＂C＂ shape and the nose points of start and finish precipitation were about 5 s at 920 ℃ and 2 815 s at 940 ℃, respectively. In addition, the nucleation of δ was heterogeneous. The nucleation sites varied with temperatures, including dislocation, grain boundary and stacking fault within γ″ phase. And 3 particles grew quickly at higher temperature with lower density. Moreover, the driving force of nucleation was mainly including chemical free energy, interracial energy and disloca- tion distorted energy. And the dislocation distorted energy could decide the density of nucleation in the strain-induced process.

Clinically applicable Gleason grading(GD)system for prostate cancer based on deep learning

To the Editor:Prostate cancer is one of the most common malignant tumors of the male genital system,with approximately 1.1 million new cases in 2012.[1]The accurate diagnosis of prostate cancer leads to a better chance of successful treatment when it is still confined to the prostate gland.The Gleason grading(GD)system was first established by Donald Gleason during 1966 to 1974.[2,3]The Gleason pattern ranges from 1 to 5.A higher score corresponds to poorer differentiation,which indicates a worse prognosis and higher metastasis possibility.The total score is calculated with the first half of the dominant Gleason pattern and the second half based on the non-dominant one.