Electromagnetic responses on microstructures of duplex stainless steels based on 3D cellular and electromagnetic sensor finite element models

Microstructures determine mechanical properties of steels,but in actual steel product process it is difficult to accurately control the microstructure to meet the requirements.General microstructure characterization methods are time consuming and results are not rep-resentative for overall quality level as only a fraction of steel sample was selected to be examined.In this paper,a macro and micro coupled 3D model was developed for nondestructively characterization of steel microstructures.For electromagnetic signals analysis,the relative permeability value computed by the micro cellular model can be used in the macro electromagnetic sensor model.The effects of different microstructure components on the relative permeability of duplex stainless steel(grain size,phase fraction,and phase distribu-tion)were discussed.The output inductance of an electromagnetic sensor was determined by relative permeability values and can be val-idated experimentally.The findings indicate that the inductance value of an electromagnetic sensor at low frequency can distinguish dif-ferent microstructures.This method can be applied to real-time on-line characterize steel microstructures in process of steel rolling.

Progress in weldability research of duplex stainless steels

Duplex stainless steels(DSSs)show better corrosion resistance with higher strength than traditional austenite stainless steels in many aggressive environments,and can be welded properly with almost every welding processes,if proper heat input is provided.Progresses of research works on weldability of DSSs in recent years are reviewed in this paper.Balance control of ferrite/austenite phases is most important for DSSs welding.The phases balance can be controlled with filler materials,nitrogen addition in shielding gas,heat input,post weld heat treatment,and alternating magnetic field.Too high cooling rate results in not only extra ferrite,but also chromium nitride precipitation.While too low cooling rate or heating repeatedly results in precipitation of secondary austenite and intermetallic compounds.In both situations,mechanical properties and corrosion resistance of the DSS joints deteriorate.Recommended upper and lower limits of heat input and maximum interpass temperature should be observed.

新型HiDEF测序技术能揭示人类机体遗传突变最早期迹象

据Liu MH 2024年6月12日[Nature,2024,630(8017):752-761.]报道,纽约大学Grossman医学院研究人员通过研究引入一种称之为发夹双重增强保真测序(Hairpin Duplex Enhanced Fidelity Sequencing,HiDEF-seq)技术,其或能准确检测突变发生之前DNA代码中发生的早期分子改变。HiDEF-seq技术能以极高的准确度检测双链突变,每分析100万亿个碱基对大约就会读取一个记录错误。HiDEF-seq技术能促进人们对健康细胞和癌细胞中突变发生基本原因的理解,以及随着人类年龄增长机体细胞中的遗传突变是如何自然积累的;相关研究结果有望帮助揭开DNA突变发生的最早期阶段。DNA是由两条分子代码(碱基)组成的链,每条链都是由4种碱基组成,即腺嘌呤(A)、胸腺嘧啶(T)、鸟嘌呤(G)和胞嘧啶(C),每条链中碱基以特定的模式与另一条链中的碱基配对,即A与T配对、C与G配对,使得DNA代码能被复制,并准确从一代细胞传递到下一代细胞。重要的是,突变是存在于DNA双链中DNA代码发生的改变,比如C与G形成的碱基对(一条链上的G与另一条链上的C配对,C-G)就可以突变形成A-T碱基对。

Characteristics of microstructure and performance of laser-treated electroless Ni-P/Ni-W-P duplex coatings

Characteristics of microstructures of electroless Ni-P/Ni-W-P duplex coatings were investigated using SEM/EDX and XRD analysis techniques. Microhardness and wear behaviour of the coatings before and after laser crystallization were evaluated by measurements of hardnesses of coating surface and cross-section, and by unlubricated friction and wear experiments. The results indicate that it is possible to prepare electroless Ni-P/Ni-W-P duplex coatings by sequential immersion in two different plating baths. After laser crystallization, the microstructures of electroless Ni-P/Ni-W-P duplex coatings present the characteristics of higher degree of crystallization and larger grain size for outer layer Ni-W-P than inner Ni-P, but outer layer has a higher hardness. The wear resistance of laser-treated duplex coatings in a given process parameter conditions is superior to the as-plated ones. Laser treatment was performed directly in air without argon protection, which provides the possibility for application of industrialized production.

老年脑缺血患者颅外段颈动脉的Duplex、MRA、DSA检查结果分析（附105例报告）

本文报告１０５例老年脑缺血患者作颅外段颈动脉彩色超声（Ｄｕｐｌｅｘ）或／和磁共振造影（ＭＲＡ）、数控减影血管造影（ＤＳＡ）、手术探查的检查结果。甲组短暂性脑缺血（ＴＩＡ）患者７７例，经上述检查发现颈动脉存在不同程度的斑块性狭窄有４４例（５１．１％），乙组脑梗塞恢复后患者２８例，颈动脉存在不同程度狭窄有１４例（５０．０％）。全组１０５例检出颈动脉有斑块性狭窄５８例（５５．２％）。作者在讨论中指出对脑缺血患者的颈动脉病变的筛选检查方法首选为彩色超声扫描。作者认为确诊颈动脉存在７０％以上狭窄者，颈动脉内膜剥脱术是最好的治疗方法。

女性盆腔及早孕的双功多普勒诊断进展

女性盆腔和早孕的双工多普勒超声显像(duplex doppler ultrasonography;DUS)诊断目前处于初始阶段。本文简介其有关最新研究成果,对今后深入工作将特别有用。一、盆腔血管系正常髂总、髂外动脉内用DUS扫查产生高阻抗、舒张期反向的血流信号,与主动脉远端和股动脉所见相似。

Clinical implication of VEGF serum levels in cirrhotic patients with or without portal hypertension

AIM To determine whether serum vascular endothelial growth factor (VEGF) levels correlates with the severity of liver cirrhosis and whether portal hypertension impacts on the expression of serum VEGF protein. METHODS Fifty three patients (mean age 56±2 years) with HCV ( n =26), HBV ( n =13), and cryptogenic liver cirrhosis ( n =14) (Child Pughs class A: 24, B: 19 and C: 12) and normal renal function constitute the patient population, who were all diagnosed by clinical, histological and radiological findings. Six healthy people and six patients with acute hepatitis served as controls. Severity of liver disease was evaluated by the CP score. Serum levels of IGF 1 and VEGF were measured by radioimmunoassay and ELISA, respectively. Portal hypertension was assessed using pulsed Doppler ultrasound. RESULTS The mean serum VEGF levels in all cirrhotic patients (73±58) were significantly lower than those of healthy controls (360±217, P <0 01) and acute hepatitis (1123±1261, P <0 01) respectively. No significant difference in median serum VEGF levels were noted among the different Child Pughs classes (class A: median, 49 4ng/L , range, 21ng/L - 260ng/L , Class B: median 59 9ng/L ; range 21-92, and Class C: median 69; range 20ng/L - 247ng/L ). A significant correlation was noted between serum VEGF and two accurate parameters of portal hypertension: portal blood flow velocity ( r =0 6) and spleen size ( r =0 55). No correlation was found between VEGF serum levels and serum albumin, IGF 1, platelets count and aminotrasnferases ( r =0 2, r =0 1, r =0 2 and r =0 2, respectively). CONCLUSION Circulating VEGF level in patients with liver cirrhosis could not serve as an indicator of the progression of chronic liver disease but rather, they may reflect increased portal hypertension or decreased hepatic regenerative activity or the combination of both.

Update in management of mesenteric ischemia

Mesenteric ischemia disorders are precipitated by a circulation insufficiency event that deprives one or several abdominal organs of adequate respiration to meet metabolic demands. Although mesenteric ischemia occurs infrequently, the mortality rate is from 60% to 100%, depending on the source of obstruction. The successful outcome is dependent upon a high index of suspicion and prompt management. We briefly review the pathophysiology and presentation of the various ischemic entities and review the current state of the art in diagnosis and treatment. Despite advances in both diagnosis and treatment, prompt diagnosis and supportive care remain critical for successful outcome. New imaging techniques, endovascular therapy and emerging research may improve our approach to this deadly condition.

Identification of Orientia tsutsugamushi,spotted fever group and typhus group Rickettsia by duplex and nested PCR methods

Objective:To identify members of genera of rickettsia and O.tsutsugammhi simultaneously.Methods:Rapid and duplex and nested PCR methods have been established by designing primers based on the conserved regions of heat shock protein GroEL gene.345 mouse viscera samples including liver,spleen and kidney,96 Xenopsylla cheopis and 32 chiggers collected from Hongta areas of Yuxi city,Yunnan province were tested by the new PCR methods.Results:The result of the study showed that the new PCR methods could identify most members of genera -Rickettsia and Orientia simultaneously with 100%specificity and its sensitivity could test one copy per microliter.The results of detection prevalence of rickettsioses in mouse,flea and mites DNA samples showed that the total rickettsia infection rate in mouse was 34.78%(120/345).The total infection rates in R.typhi,O.t Karp and R.sibirica of mouse samples were 28.12%(97/345),19.71%(68/345) and O. 29%(1/345) respectively.Co-infection rates in R.typhi and 0.t Karp of mouse samples were 13.33%(46/ 345).O.t Karp type has been the main epidemic strain in these areas.Conclusion:We concluded that this PCR method could be used to detect multi-genera rickettsia simultaneously.Molecular evidences provided in this and previous studies strongly support that Hongta areas of Yuxi city are a natural focus for typhus and scrub typhus with the common occurrence of their confection.

Liquid biopsy for non-invasive assessment of liver injury in hepatitis B patients

BACKGROUND Hepatitis B is a major public health problem in China. Accurate liver injury assessment is essential for clinical evidence-based treatment. Liver biopsy is considered the gold standard method to stage liver disease, but it is not widely used in resource-limited settings. Therefore, non-invasive liquid biopsy tests are needed. AIM To assess liver injury in hepatitis B patients using quantified cell free DNA combined with other serum biomarker as a liquid biopsy-based method. METHODS A cohort of 663 subjects including 313 hepatitis B patients and 350 healthy controls were enrolled. Ultrasound-guided liver biopsies followed by histopathological assessments were performed for the 263 chronic hepatitis B patients to determine the degree of liver injury. Cell-free DNA was quantified using a novel duplex real-time polymerase chain reaction assay. RESULTS Compared with healthy controls, patients with hepatitis B virus (HBV) infection had significantly higher plasma DNA, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, and HBV DNA levels (P<0.01). Serum ALT, AST, bilirubin, and plasma DNA levels of patients with markedsevere inflammation were significantly higher than those with mild-moderate inflammation (P<0.01). There was a statistically significant correlation between hepatocyte inflammation severity and serum bilirubin (R^2=0.673, P<0.01) or plasma DNA (R^2=0.597, P<0.01) levels. The areas under the curves of serum ALT, bilirubin, plasma DNA, and their combination to distinguish between patients with mild–moderate and marked-severe inflammation were 0.8059, 0.7910, 0.7921, and 0.9564, respectively. CONCLUSION The combination of plasma DNA, serum ALT, and bilirubin could be a candidate liquid biopsy for non-invasive assessment of liver injury in hepatitis B patients.

Hot deformation behavior of microstructural constituents in a duplex stainless steel during high-temperature straining

The hot deformation characteristics of 1.4462 duplex stainless steel （DSS） were analyzed by considering strain partitioning between austenite and ferrite constituents. The individual behavior of ferrite and austenite in microstructure was studied in an iso-stress condition. Hot compression tests were performed at temperatures of 800-1100~C and strain rates of 0.001-1 s-1. The flow stress was modeled by a hyperbolic sine constitutive equation, the corresponding constants and apparent activation energies were determined for the studied alloys. The constitutive equation and law of mixture were used to measure the contribution factor of each phase at any given strain. It is found that the contribution factor of ferrite exponentially declines as the Zener-HoUomon parameter （Z） increases. On the contrary, the austenite contribution polynomially increases with the increase of Z. At low Z values below 2.6. x 1015 （lnZ---35.5）, a negative contribution factor is determined for austenite that is attributed to dynamic recrystallization. At high Z values, the contribution factor of austenite is about two orders of magnitude greater than that of ferrite, and therefore, austenite can accommodate more strain. Microstructural characterization via electron back-scattered diffraction （EBSD） confirms the mechanical results and shows that austenite recrystallization is possible only at high temperature and low strain rate.

Effect of Temperature and Cl^- Concentration on Pitting of 2205 Duplex Stainless Steel

The electrochemical behaviors of 2205 duplex stainless steel in NaCl solution with different temperatures and concentrations were studied by gravimetric tests, potentiodynamic polarization, electrochemical impedance spectroscopy and scanning electron microscopy. The experinental results show that temperature and chloride concentration have a great influence on the pitting resistance of 2205 duplex stainless steels. They not only effect the corrosion rate of pitting, but also change the shape of the pits. When NaCl solution was in low concentration and temperature below the critical pitting temperature, pits were very small and scattered with hemisphere-like shape. On the contrary, the pits of 2205 duplex stainless steel were large and sometimes had a lacy cover when the NaCl concentration was higher and the temperature was 70℃.

Structural Characteristics and Formation Mechanism in the Micangshan Foreland,South China

Lying at the junction of the Dabashan, Longmenshan and Qinling mountains, the Micangshan Orogenic Belt coupled with a basin is a duplex structure and back-thrust triangular belt with little horizontal displacement, small thrust faults and continuous sedimentary cover. On the basis of 3D seismic data, and through sedimentary and structural research, the Micangshan foreland can be divided into five subbelts, which from north to south are： basement thrust, frontal thrust, foreland depression-back-thrust triangle, foreland fold belt or anticline belt, and the Tongjiang Depression. Along the direction of strike from west to east, the arcuate structural belt of Micangshan can be divided into west, middle and east segments. During the collision between the Qinling and Yangtze plates, the Micangshan Orogenic Belt was subjected to the interaction of three rigid terranes： Bikou, Foping, and Fenghuangshan （a.k.a. Ziyang） terranes. The collision processes of rigid terranes controlled the structural development of the Micangshan foreland, which are： （a） the former collision between the Micangshan-Hannan and Bikou terranes forming the earlier rudiments of the structure; and （b） the later collision forming the main body of the structural belt. The formation processes of the Micangshan Orogenic Belt can be divided into four stages： （1） in the early stage of the Indosinian movement, the Micangshan-Hannan Rigid Terrane was jointed to the Qinling Plate by the clockwise subduction of the Yangtze Plate toward the Qinling Plate; （2） since the late Triassic, the earlier rudiments of the Tongnanba and Jiulongshan anticlines and corresponding syncline were formed by compression from different directions of the Bikou, Foping and Micangshan-Hannan terranes; （3） in the early stage of the Himalayan movement, the Micangshan-Hannan Terrane formed the Micangshan Nappe torwards the foreland basin and the compression stresses were mainly concentrated along both its flanks, whereas the Micangshan-Hannan Terrane wedged into the Qinling Orogenic Belt with force; （4） in the late stage of the Himalayan movement, the main collision of the Qinling Plate made the old basement rocks of the terrane uplift quickly, to form the Micangshan Orogenic Belt. The Micangshan foreland arcuate structure was formed due to the non-homogeneity of terrane movement.

Tooth surface geometry optimization of spiral bevel and hypoid gears generated by duplex helical method with circular profile blade

In order to effectively improve meshing performance of spiral bevel and hypoid gears generated by the duplex helical method, the effects of straight lined and circular cutting edges profile on meshing and contact of spiral bevel and hypoid gears were investigated analytically. Firstly, a mathematical model of spiral bevel and hypoid gears with circular blade profile was established according to the cutting characteristics of the duplex helical method. Based on a hypoid gear drive, the tooth bearings and the functions of transmission errors of four design cases were analyzed respectively by the use of the tooth contact analysis(TCA), and the contact stresses of the four design cases were analyzed and compared using simulation software. Finally, the curvature radius of the circular profile blade was optimized. The results show that the contact stresses are availably reduced, and the areas of edge contact and severe contact stresses can be avoided by selecting appropriate circular blade profile. In addition, the convex and concave sides are separately modified by the use of different curvature radii of inside and outside blades, which can increase the flexibility of the duplex helical method.

A duplex PCR for the rapid and simultaneous detection of Brucella spp.in human blood samples

Objective:To design a duplex PCR for rapid and simultaneous detection of Brucella species, in human blood samples.Methods:Fifty-two peripheral bloods samples were collected from suspicious patients with brucellosis.Following DNA extraction,PCR assay were performed, using three primers that could simultaneously identify and differentiate three major species of pathogenic Brucella in humans and animals.Results:Of the 52 peripheral bloods samples tested, 25 sample(48%) showed positive reactions in PCR.Twelve samples were positive for Brucella abortus(B.abortus)(23%,13 for Brucella melUensis(B.melUensis)(25%) and 0 for Brucella ovis (6.ovis)(Ow.Conclusions:This work de=monstrates dial in case where specific primers were utilized,duplex PCR has proved to be a simple,fast,and relatively inexpensive method for simultaneous detection of important species of Brucella in clinical samples.

Comparison of explosive welding of pure titanium/SUS 304 austenitic stainless steel and pure titanium/SUS 821L1 duplex stainless steel

Pure commercial titanium was welded with two types of stainless steel,namely SUS 304 austenitic stainless steel and SUS 821L1 duplex stainless steel.The wavy interface of SUS 821L1 was smaller than that of SUS 304.The vortex zone was observed from both longitudinal and transverse directions,and its composition was analyzed.The interface of Ti/SUS 821L11 was able to bear 401−431 MPa shear load while that of Ti/SUS 304 could withstand 352−387 MPa.The weldability window was used to analyze experimental phenomenon.Furthermore,the smoothed particle hydrodynamics(SPH)numerical simulation method was used to simulate the wavy interface.The trend of wavelength and amplitude change with strength and the stand-offs was consistent with the experimental results.

The Full-Duplex Artificial Noise Scheme for Security of a Cellular System

This paper focuses on the problem of secure transmission in a cellular system. A full-duplex base station using artificial noise is adopted to improve both the uplink and downlink secrecy rate via pairing terminals which reverses the downlink and uplink of each other. We give the designs of artificial noise and the user's desired signal, and derive the pairing prin-ciple between terminals. Moreover, the influence of self-interference cancellation on secrecy rate is ex-plored. Simulation results show that the secrecy rate can get much better performance by adopting full-duplex artificial noise scheme and proposed pair-ing method. The downlink secrecy rate decreases with the distance between terminals. Besides the uplink secrecy rate is sensitive to the ability of self-interference cancellation.