Interconnected microstructure and flexural behavior of Ti_(2)C-Ti composites with superior Young’s modulus

To enhance the Young’s modulus(E)and strength of titanium alloys,we designed titanium matrix composites with intercon-nected microstructure based on the Hashin-Shtrikman theory.According to the results,the in-situ reaction yielded an interconnected microstructure composed of Ti_(2)C particles when the Ti_(2)C content reached 50vol%.With widths of 10 and 230 nm,the intraparticle Ti lamellae in the prepared composite exhibited a bimodal size distribution due to precipitation and the unreacted Ti phase within the grown Ti_(2)C particles.The composites with interconnected microstructure attained superior properties,including E of 174.3 GPa and ultimate flexural strength of 1014 GPa.Compared with that of pure Ti,the E of the composite was increased by 55% due to the high Ti_(2)C content and interconnected microstructure.The outstanding strength resulted from the strong interfacial bonding,load-bearing capacity of interconnected Ti_(2)C particles,and bimodal intraparticle Ti lamellae,which minimized the average crack driving force.Interrupted flexural tests revealed preferential crack initiation along the{001}cleavage plane and grain boundary of Ti_(2)C in the region with the highest tensile stress.In addition,the propagation can be efficiently inhibited by interparticle Ti grains,which prevented the brittle fracture of the composites.

PROS1基因新同义突变致以脑梗死起病的遗传性蛋白S缺陷症家系调查

目的调查一个以急性脑梗死起病的遗传性蛋白S缺陷症家系的临床特征,分析其PROS1基因的突变特点。方法收集先证者及其直系亲属的临床资料,采集血标本,检测蛋白S活性水平并对PROS1基因进行测序。结果该家系直系亲属三代8人,其中3名确诊为遗传性蛋白S缺陷症,先证者及其兄均表现为急性脑梗死,余家系成员尚未发生血栓事件。检测蛋白S活性:先证者、先证者之兄、先证者母亲分别为16.8%、38.0%、31.8%,父亲正常。基因分析发现先证者、先证者之兄、先证者母亲PROS1基因第11外显子均存在c.1323G>A杂合变异,父亲为野生型。结论本家系为一个新发现的由PROS1基因c.1323G>A同义突变引起的遗传性蛋白S缺陷症家系;此突变可能导致青年缺血性脑卒中的发生。

剪切波弹性成像评估甲巯咪唑治疗初诊Graves病疗效的应用价值

目的 探讨超声剪切波弹性成像(shear wave elastography, SWE)技术评估甲巯咪唑治疗初诊Graves病疗效的临床应用价值。方法 收集60例经滨州医学院附属医院初诊确诊为Graves病的患者,给予服用甲巯咪唑进行治疗,检测治疗前及治疗2月后患者血清甲状腺功能指标包括血清促甲状腺激素(thyrotropin, TSH)、血清游离三碘甲状腺原氨酸(free triiodothyronine, FT3)和血清游离甲状腺素(free thyroxine, FT4),以及甲状腺自身免疫性炎症指标促甲状腺激素受体抗体(TRAb)。同时应用SWE技术分别测量患者治疗前及治疗2月后甲状腺组织的杨氏模量最大值、最小值和平均值,应用配对t检验对治疗前后的结果进行分析比较。结果 比较治疗前及治疗2月后结果显示,所测血清甲状腺功能指标(TSH、FT3、FT4)显著改善(P<0.01),TRAb显著好转(P<0.05);应用SWE技术测得患者甲状腺组织的各项杨氏模量值也有显著变化(P<0.01)。结论 SWE技术测得甲状腺组织杨氏模量值的变化与患者甲状腺功能指标变化的临床意义一致,说明SWE实时、定量且客观获取的患者甲状腺组织的硬度变化信息,可为临床医师准确评估Graves病治疗效果及调整用药剂量提供重要的量化参考依据,具有较高的临床应用价值。

经会阴三维超声联合SWE评估分娩方式对初产妇肛提肌的影响

目的探讨经会阴三维超声联合剪切波弹性成像技术(shear wave elastography,SWE)在评估分娩方式对初产妇肛提肌形态及功能影响中的应用价值,为早期诊断盆底功能障碍性疾病(pelvic floor disorders,PFD)提供新方法。方法选取在笔者医院分娩后6~8周复查的92例初产妇为产后组,根据其分娩方式分为经阴道分娩组(n=45)和剖宫产组(n=47),选取同期健康未育女性作为对照组(n=43)。采用经会阴三维超声联合SWE进行检查,比较各组间不同状态下肛提肌裂孔形态参数及弹性参数的差异。结果经阴道分娩组在静息、最大缩肛及最大Valsalva状态下肛提肌裂孔面积(levator ani hiatus area,LHA)均大于剖宫产组和对照组,剖宫产组大于对照组,差异有统计学意义(P<0.01);经阴道分娩组在静息及最大缩肛状态下弹性参数较对照组、剖宫产组均减小,差异有统计学意义(P<0.01);而剖宫产组与对照组弹性参数比较,差异无统计学意义(P>0.05);最大Valsalva状态与静息状态下LHA差值(ΔA′)与双侧PR杨氏模量值收缩前后的差值(ΔE)呈显著负相关(左侧r=-0.444,P=0.008;右侧r=-0.488,P=0.002)。结论经会阴三维超声联合SWE可定量评估肛提肌的形态及功能,为PFD的早期诊断提供依据。

Application of real-time shear wave elastography to Achilles tendon hardness evaluation in older adults

BACKGROUND Real-time shear wave elastography(SWE)is a non-invasive imaging technique used to measure tissue stiffness by generating and tracking shear waves in real time.This advanced ultrasound-based method provides quantitative information regarding tissue elasticity,offering valuable insights into the mechanical properties of biological tissues.However,the application of real-time SWE in the musculoskeletal system and sports medicine has not been extensively studied.AIM To explore the practical value of real-time SWE for assessing Achilles tendon hardness in older adults.METHODS A total of 60 participants were enrolled in the present study,and differences in the elastic moduli of the bilateral Achilles tendons were compared among the following categories:(1)Age:55-60,60-65,and 65-70-years-old;(2)Sex:Male and female;(3)Laterality:Left and right sides;(4)Tendon state:Relaxed and tense state;and(5)Tendon segment:Proximal,middle,and distal.RESULTS There were no significant differences in the elastic moduli of the bilateral Achilles tendons when comparing by age or sex(P>0.05).There were,however,significant differences when comparing by tendon side,state,or segment(P<0.05).CONCLUSION Real-time SWE plays a significant role compared to other examination methods in the evaluation of Achilles tendon hardness in older adults.

Effects of reservoir fluids on sand packs consolidated by furan and epoxy resins:Static and dynamic states

One of the most effective methods for sand control is the chemical consolidation of sandstone structures.In this paper,the impacts of crude oil and brine in the static state and the impact of the flow rates of the fluids in the dynamic state have been assessed at the reservoir conditions.The analyses in this research were Young’s modulus,compressive strength,porosity,and permeability which were done on core samples after and before fluid contact.Samples made with two different resins showed good resistance to crude oil in both states.No considerable change was seen in the analyses even at high crude oil injection rates in the dynamic state.Conversely,brine caused a noticeable change in the analyses in both states.In the presence of brine at the static state,Young’s modulus and compressive strength respectively decreased by 37.5%and 34.5%for epoxy cores,whereas these parameters respectively reduced by 30%and 41%for furan cores.In brine presence at the dynamic state,compressive strength reduction was 10.28 MPa for furan and 6.28 MPa for epoxy samples and their compressive strength reached 16.75 MPa and 26.54 MPa respectively which are higher than the critical point to be known as weak sandstone core.Moreover,Young’s modulus decrease values for furan and epoxy samples were respectively 0.37 GPa and 0.44 GPa.Therefore,brine had a more destructive effect on the mechanical characteristics of samples in the static state than the dynamic one for two resins.In addition,brine injection increased permeability by about 13.6%for furan and 34.8%for epoxy.Also,porosity raised by about 21.8%for furan,and 19%for epoxy by brine injection.The results showed that the chemical sand consolidation weakens in the face of brine production along with crude oil which can lead to increasing cost of oil production and treating wellbore again.

Kimberly S.Young关于网络成瘾的15年研究述评

美国匹兹堡大学的Kimberly S.Young作为系统研究网瘾的先驱之一,她对于人类网络成瘾奥秘的追问与探究在过去的15年(1996-2011)里从未间断。本文追踪评述了Young对于网络成瘾的界定与分类,关于网络成瘾产生机理的研究,两度开发的网络成瘾诊断问卷和治疗网瘾的认知行为疗法。

Wagnild-Young心理弹性量表(RS-11)中文版的信效度检验

目的对Wagnild-Young心理弹性量表(RS-11)进行初步的修订和信效度检验。方法根据量表修订的方法,选取某大学在校生3363名进行测试,分析中文版的信、效度。结果项目分析结果表明RS-11各项目的项目鉴别力良好(r=0.344～0.700);内部一致性系数为0.807,分半信度为0.865,量表的重测信度为0.617;与CD-RISC-25关联效度为0.725;与大五人格和SCL-90关联效度理想。结论修订的Wagnild-Young心理弹性量表(RS-11)具有较高的信度和效度。

PSO algorithm for Young's modulus reconstruction

To get the quantitive value of abnormal biological tissues, an inverse algorithm about the Young＇s modulus based on the boundary extraction and the image registration technologies is proposed. With the known displacements of boundary tissues and the force distribution, the Young＇s modulus is calculated by constructing the unit system and the inverse finite element method （IFEM）. Then a tough range of the modulus for the whole tissue is estimated referring the value obtained before. The improved particle swarm optimizer （PSO） method is adopted to calculate the whole Yong＇s modulus distribution. The presented algorithm overcomes some limitations in other Young＇s modulus reconstruction methods and relaxes the displacements and force boundary condition requirements. The repetitious numerical simulation shows that errors in boundary displacement are not very sensitive to the estimation of next process; a final feasible solution is obtained by the improved PSO method which is close to the theoretical values obtained during searching in an extensive range.

关于Young’s不等式证明的一个注记

给出Youngs不等式的新证明和一个注记.

多晶Cu中Young's模量和硬度与晶体取向的关系

采用纳米压入(nanoindentation)和电子背散射衍射(EBSD)技术对多晶Cu样品多个晶粒进行了微观力学性能表征和晶体取向分析.结果表明,Young's模量随晶粒表面法向方向<hkl>与<111>和<001>最小夹角的变化有明显的规律:<hkl>越接近<111>,其Young's模量越大;<hkl>越接近<001>,其Young's模量越小;而Young's模量随<hkl>与<110>最小夹角的变化无明显规律.硬度随<hkl>与<111>,<110>和<001>最小夹角的变化均无明显规律.通过理论计算讨论了上述规律性.

Measurement of Young's Modulus and Poisson's Ratio of Thermal Barrier Coatings

In gas turbines, thermal barrier coatings （TBCs） applied by air plasma spraying are widely used to lower the temperature of hot components. To analyze the characteristics of TBCs such as residual stress, bond strength, fracture toughness, and crack propagation ratio, the Young＇s modulus and Poisson＇s ratio are important parameters. For TBC is a brittle and thin film, it is desirable to evaluate those properties while the coatings are bonded to a substrate. An atmospheric plasma spray MCrAIY bond coat and Yttria stabilized zirconia （YSZ） top coat are deposited onto a nickel-base superalloy GH150 substrate. The Young＇s modulus and Poisson＇s ratio are measured by cantilever beam bending with NDI. The method will be developed to test the Young＇ s modulus and Poisson ratio of other multilayer systems.

Effects of porosity on seismic velocities, elastic moduli and Poisson's ratios of solid materials and rocks

The generalized mixture rule(GMR) is used to provide a unified framework for describing Young’s(E),shear(G) and bulk(K) moduli, Lame parameter(l), and P- and S-wave velocities(Vpand Vs) as a function of porosity in various isotropic materials such as metals, ceramics and rocks. The characteristic J values of the GMR for E, G, K and l of each material are systematically different and display consistent correlations with the Poisson’s ratio of the nonporous material(v0). For the materials dominated by corner-shaped pores, the fixed point at which the effective Poisson’s ratio(n) remains constant is at v0=0.2, and J(G) > J(E) > J(K) > J(l) and J(G) < J(E) < J(K) < J(l) for materials with v0> 0.2 and v0< 0.2, respectively.J(Vs) > J(Vp) and J(Vs) < J(Vp) for the materials with v0> 0.2 and v0< 0.2, respectively. The effective n increases, decreases and remains unchanged with increasing porosity for the materials with v0< 0.2,v0> 0.2 and v0=0.2, respectively. For natural rocks containing thin-disk-shaped pores parallel to mineral cleavages, grain boundaries and foliation, however, the n fixed point decreases nonlinearly with decreasing pore aspect ratio(a: width/length). With increasing depth or pressure, cracks with smaller a values are progressively closed, making the n fixed point rise and finally reach to the point at v0=0.2.

A method to determine Young's modulus of soft gels for cell adhesion

A convenient technique is reported in this note for measuring elastic modulus of extremely soft material for cellular adhesion. Specimens of bending cylinder under gravity are used to avoid contact problem between testing device and sample, and a beam model is presented for evaluating the curvatures of gel beams with large elastic deformation. A self-adaptive algorithm is also proposed to search for the best estimation of gels＇ elastic moduli by comparing the experimental bending curvatures with those computed from the beam model with preestimated moduli. Application to the measurement of the property of polyacrylamide gels indi- cates that the material compliance varies with the concentrations of bis-acrylamide, and the gels become softer after being immersed in a culture medium for a period of time, no matter to what extent they are polymerized.

Prediction and optimization of process variables to maximize the Young’s modulus of plasma sprayed alumina coatings on AZ31B magnesium alloy

Like other manufacturing techniques,plasma spraying has also a non-linear behavior because of the contribution of many coating variables.This characteristic results in finding optimal factor combination difficult.Subsequently,the issue can be solved through effective and strategic statistical procedures integrated with systematic experimental data.Plasma spray parameters such as power,stand-off distance and powder feed rate have significant influence on coating characteristics like Young’s modulus.This paper presents the use of statistical techniques in specifically response surface methodology(RSM),analysis of variance,and regression analysis to develop empirical relationship to predict Young’s modulus of plasma-sprayed alumina coatings.The developed empirical relationships can be effectively used to predict Young’s modulus of plasma-sprayed alumina coatings at 95%confidence level.Response graphs and contour plots were constructed to identify the optimum plasma spray parameters to attain maximum Young’s modulus in alumina coatings.A linear regression relationship was established between porosity and Young’s modulus of the alumina coatings.

Experimental Study on Young′s Modulus of Concrete

Young′s Modulus of concrete is studied on the basis of triaxial compressive experiments. The authors proposed two empirical equations to calculate its static Young′s modulus and dynamic Young′s modulus when dynamic Poisson ratio μ d varies nearby 0.20.P wave velocity and elastic modulus have the same varying tendency as letter N. μ,μ d decrease with the increase of loading rate and μ d has a great effect on the parameters E d and E D.

Approximate expression of Young's equation and molecular dynamics simulation for its applicability

In 1805, Thomas Young was the first to propose an equation(Young's equation) to predict the value of the equilibrium contact angle of a liquid on a solid. On the basis of our predecessors, we further clarify that the contact angle in Young's equation refers to the super-nano contact angle. Whether the equation is applicable to nanoscale systems remains an open question. Zhu et al. [College Phys. 4 7(1985)] obtained the most simple and convenient approximate formula, known as the Zhu–Qian approximate formula of Young's equation. Here, using molecular dynamics simulation, we test its applicability for nanodrops. Molecular dynamics simulations are performed on argon liquid cylinders placed on a solid surface under a temperature of 90 K, using Lennard–Jones potentials for the interaction between liquid molecules and between a liquid molecule and a solid molecule with the variable coefficient of strength a. Eight values of a between 0.650 and 0.825 are used. By comparison of the super-nano contact angles obtained from molecular dynamics simulation and the Zhu–Qian approximate formula of Young's equation, we find that it is qualitatively applicable for nanoscale systems.

ELECTRIC FIELD EFFECTS ON YOUNG'S MOLULUS OF NANOWIRES

As an important component of nanodevices and nanomachine constructions, the mechanical performance of nanowires （NWs） has been a subject of intense research efforts due to gaining relevance in controlling functionality of nanoelectromechanical systems （NEMS）; meanwhile, one of the characteristics of the NEMS is the dependence of the functionality of the systems upon the applied electric field. The study of the electric effects on the Young＇s modulus of nanostructures is of certain usefulness in the design of NEMS and the precise measurement of mechanical properties of one-dimensional nanostructures. This paper reviews the origin of the size-dependence of the elastic property of NWs and the factors influencing the discrepancies and inconsistencies in the measured values of the Young＇s modulus for the NW, besides the surface effects, nonlinear effects, the electromechanical coupling effects as a possible effect responsible for the differences in quantitative and qualitative performance of the measured Young＇s modulus for the NWs versus the diameter are clarified.

CALCULATION OF THE YOUNG'S MODULUS OF AN ADSORBED POLYMER LAYER

Polymer layers adsorbed to a surface or in a confined environment often change their mechanical properties. There is even the possibility of solidification of the confined layer. To judge the stiffness of such a layer, we used the Hertz model to calculate the Young＇s modulus of the polymer layer in the confinement of AFM experiments with silicon nitride tip with a radius of curvature ofR ≈ 50 nm and a glass sphere attached to the cantilever R =5 μm. Since there is no visible indentation of the layer in the AFM experiments, the layer is either penetrated very easily, or the indentation is too small to be seen in a force curve. The latter would be the case for a polymer layer with a Young＇s modulus above 4 × 10^8 Pa in case of an experiment with a silicon nitride tip and 4×10^5 Pa in case of a glass sphere.

Young blood products:emerging treatment for Alzheimer's disease?

Alzheimer＇s disease is the most common neurodegenerative disorder and no disease-modifying treatment is currently available.Research has shown that while brain neurogenesis continues in adult life,it declines with age.Using parabiosis,plasma transfusions and direct administration of neural growth factors,animal studies have demonstrated the positive impact of exposure to young blood products on neurogenesis and synaptic plasticity in an aging brain.The hippocampus and the sub-ventricular zones were identified as the main regions affected.Promising findings have prompted researchers to experiment their effects in subjects with an established neurocognitive disorder,such as Alzheimer＇s disease.They argued that modification of brain vasculature,reactivation of adult neural stem cells,and remodeling of their synaptic activity/plasticity may lead to cognitive enhancement and increased neurogenesis.One pilot human study found that young donor plasma infusion protocols for adults with Alzheimer＇s disease were safe and feasible;however,no statistically significant improvements in cognition were detected.There is a need to conduct additional placebo-controlled human studies in larger samples.Future studies should focus on identifying an “optimal age” at which an intervention in humans may yield significant cognitive enhancement,as well as determining the types of transfusions with the best efficacy and tolerability profiles.