Discussion and prediction on decreasing flow stress scale effect

Based on crystal plasticity theory and surface layer model, relation of flow stress to billet dimension and grain size was built, and rationality of derived relation was verified with tensile tests of different size billets. With derived expressions, relation of decreasing flow stress scale effect to billet dimension, grain size as well as billet shape was discussed and predicted. The results show that flow stress is proportional to billet size; with decrease of grain size, flow stress is less influenced by billet dimension. When both cross section area and grain size are same, flow stress decrease of rectangular section billet or sheet is larger than that of circular section billet.

Positively Worded Subscale Score of the Perceived Stress Scale Is Associated with Cognitive Domain Function

Objectives: To examine the cross-sectional associations of the separate subscales of the Perceived Stress Scale (PSS) and tests measuring cognitive domains in older adults. Methods: 897 adults over the age of 70 free of amnestic mild cognitive impairment and dementia and enrolled in the Einstein Aging Study made up the study sample. The PSS-14 was used to measure stress. Three cognitive domains (language, episodic memory, and frontal-executive) had previously been found using principle component analysis. Linear regression analyses were used to determine the relationship between the PSS subscales and cognitive domain function. Results: The study sample had a mean age of 79.1 years and 62.8% were female. Bivariate correlations show that the PSS-14 positively worded subscale of the PSS (PSS-PW) was significantly associated with all three cognitive domains (language: r = -0.15, p < 0.001;episodic memory: r = -0.16, p < 0.001;frontal-executive: r = -0.21, p <0.001) while the negatively worded subscale of the PSS (PSS-NW) was not significantly associated with any cognitive domain. In linear regression analyses adjusted for age, white race, gender, years of education, and depressive symptoms, the PSS-PW remained significantly associated with each of the cognitive domains. The PSS-NW was not associated with any cognitive domains in any model. The PSS-14 was significantly associated with language and episodic memory, but not the frontal-executive domain. Conclusion: Worse PSS-PW scores are associated with reduced cognitive function in the executive, memory, and language domains in nondemented older adults. The PSS-PW subscale correlated better with cognitive function than the overall PSS-14. Future research should evaluate the temporality of the association and if stress reduction therapies improve cognitive performance.

Transcultural Validation and Adaptation of the Academic Stress Questionnaire (CEA) in Students of Puerto Rico

Background: There are multiple questionnaires to measure academic stress in university students, which have been used in nursing students. In Puerto Rico, a questionnaire valid in content and reliability was required to measure the variable of academic stress in nursing students. Purpose: The aim of this study was to adapt transculturally and validate the Academic Stress Questionnaire (CEA) for its use in Puerto Rico. Materials and Methods: Used for the first phase of this study consisted in the evaluation of the validity of content and appearance, whereas the second phase was the actual administering of the questionnaire to 20 (twenty) nursing students, to pilot test its internal consistency using the Cronbach’s α test. Results: Validity of content and appearance allowed for the modification of the questionnaire into one, consisting of 42 items, thus eliminating 34 premises from the original 76 items the questionnaire was composed of. Furthermore, the appearance of the questionnaire was modified by placing the measuring scales in columns, adapting social, demographic, and academic data to the required Puerto Rican reality. The sections meant to measure the academic stress variables were left intact, except for the linguistics adaptation, which was accomplished by a team of experts in the Spanish language. With an α global of 0.80 and coefficients larger than 0.7 in the multi-item sub scales, which oscillated between 0.750 and 0.860, the questionnaire provides a high reliability. Conclusion: Although the values reported in this study are somewhat lower than previous research, they were comparable the Cronbach’s Alpha coefficients reported by Cabanach, in which the numbers reported are considered high (α > 0.70) which show acceptable confiability of the subscales included in the study and a high degree of consistency and thus can be relied upon in future research. In synthesis, the Academic Stress Questionnaire (CEA) modified and adapted, thoroughly fulfills the established criteria of confiability and validity to evaluate academic stress of Puertorrican nursing students.

Assessment of Stress Cognitive Control and Executive Function with Stress Control Rating Scale (ECOSTRESS) and Low Resolution Brain Electromagnetic Tomography (LORETA) (In Portuguese People in Situations of Unemployment and Economic Insufficiency)

This article reviews the constructs of stress, appraisal, coping, according to a transactional perspective, and executive function, and presents a stress control rating scale (ECOSTRESS), which design is founded in these constructs. This psychometric tool is useful in the assessment of cognitive control of stress, correlated with the function of dorsolateral prefrontal cortex. It has been validated for its use in the assessment of Portuguese people in situations of stress related to unemployment and economic insufficiency. Also, within the context of the cognitive control of stress, it is highlighted the usefulness of low resolution brain electromagnetic tomography (LORETA).

Measurement of length-scale and solution of cantilever beam in couple stress elasto-plasticity

Owing to the absence of proper analytical solution of cantilever beams for couple stress/strain gradient elasto-plastic theory, experimental studies of the cantilever beam in the micro-scale are not suitable for the determination of material length-scale. Based on the couple stress elasto-plasticity, an analytical solution of thin cantilever beams is firstly presented, and the solution can be regarded as an extension of the elastic and rigid-plastic solutions of pure bending beam. A comparison with numerical results shows that the current analytical solution is reliable for the case of σ0 〈〈 H 〈〈 E, where σ0 is the initial yield strength, H is the hardening modulus and E is the elastic modulus. Fortunately, the above mentioned condition can be satisfied for many metal materials, and thus the solution can be used to determine the material length-scale of micro-structures in conjunction with the experiment of cantilever beams in the micro-scale.

DEFLECTION METHOD FROM TWO SIDES OXIDATION TO STUDY EFFECT OF Y ON INTERNAL STRESS OF OXIDE SCALES

Au investigation was carried ont of the effect of Y addition upon the internal stress of Al_2O_3 scale formed during oxidation of sputtering coating on Co-30Cr-6Al alloy and the growth stress of oxidized film on Fe-23Cr-5Al alloy heating up to 900℃ in air,using a specially designed deflection method from thin strip specimen with coat- ings,ion-implanted Y on one side and oxidized onto both sides.Results indicate that Y may decrease the internal stress of oxide scale on 2×10^(17) Y^+/cm^2 implanted Co- 30Cr-6Al coating,and increase one on 2×10^(16) Y^+/cm^2 implanted Fe-23Cr-5Al alloy. This seems due to whether or not Y promotes the plastic deformation of oxide scale.In addition,at initial oxidation stage,the change of growth stress of oxide scale formed on Y-implanted Co-30Cr-6Al coating may be related to the influence of Y on oxidation process of the coating.

Study on the influence of La_2O_3 on Stress in α－Al_2O_3 Scale by a Novel Two－side Oxidation Bending Method

The influence of La2O3 on stress in the scales of NiAl-type coatings were studied by a novel two-side oxidation bending method during isothermal and anisothermal oxidation. The results indicate that. differences of thermal expansion coefficients of the coatings applied on the two sides of the bending sample can be analyzed by detecting the deflection behaviour of the sample, the growth stress in La2O3 added x-Al2O3 coating is reduced by some 350 kgf/ mm2 for 50 h isothermal oxidation at 900℃ . and the mechanism is that the grain size of scale is reduced due to addition of La2O3 and its plasticity is increased, the magnitude of thermal expansion coefficients of coatings influences the thermal stress developing during cooling. Stress in the scale on simple NiAl is relieved mainly in way of cracking and spalling of the scale at temperature 400￣ 600℃ ,but that on La2O3-added coating is relieved slightly due to good integrity and adherence of the scale.

Multi-scale analysis of subgrid stress and energy dissipation in turbulent channel flow

In present study, the subgrid scale （SGS） stress and dissipation for multiscale formulation of large eddy simulation are analyzed using the data of turbulent channel flow at Ret = 180 obtained by direct numerical simulation. It is found that the small scale SGS stress is much smaller than the large scale SGS stress for all the stress components. The dominant contributor to large scale SGS stress is the cross stress between small scale and subgrid scale motions, while the cross stress between large scale and subgrid scale motions make major contributions to small scale SGS stress. The energy transfer from resolved large scales to subgrid scales is mainly caused by SGS Reynolds stress, while that between resolved small scales and subgrid scales are mainly due to the cross stress. The multiscale formulation of SGS models are evaluated a priori, and it is found that the small- small model is superior to other variants in terms of SGS dissipation.

A SECOND-ORDER DYNAMIC SUBGRID-SCALE STRESS MODEL

A second-order dynamic model based on the general relation between the subgrid-scale stress and the velocity gradient tensors was proposed. A priori test of the second-order model was made using moderate resolution direct numerical simulation date at high Reynolds number ( Taylor microscale Reynolds number R-lambda = 102 similar to 216) for homogeneous, isotropic forced flow, decaying flow, and homogeneous rotating flow. Numerical testing shows that the second-order dynamic model significantly improves the correlation coefficient when compared to the first-order dynamic models.

Grain-scale Stress and GND Density Distributions around Slip Traces and Phase Boundaries in a Titanium Alloy

For TA15 titanium alloy, slip is the dominant plastic deformation mechanism because of relatively high Al content. In order to reveal the grain-scale stress field and geometrically necessary dislocation（GND） density distribution around the slip traces and phase boundaries where the slip lines are blocked due to Burgers orientation relationship（OR） missing. We experimentally investigated tensile deformation on TA15 titanium alloy up to 2.0% strain at room temperature. The slip traces were observed and identified using high resolution scanning electron microscopy（SEM） and electron backscatter diffraction（EBSD） measurements. The grain-scale stress fields around the slip traces and phase boundaries were calculated by the cross-correlationbased method. Based on strain gradient theories, the density of GND was calculated and analyzed. The results indicate that the grain-scale stress is significantly concentrated at phase/grain boundaries and slip traces. Although there is an obvious GND accumulation in the vicinity of phase and subgrain boundaries, no GND density accumulation appears near the slip traces.

页岩储层应力敏感性的时间效应

有效应力及其作用时间是控制岩石孔隙和裂缝变形的重要外部因素。页岩储层的多尺度孔隙结构特征及孔缝配置关系使得其应力敏感时间效应具有特殊性,然而,以往研究尚未考虑有效应力加载及卸载时间对页岩应力敏感行为的影响。以川南威荣气田龙马溪组页岩气藏为研究对象,钻取不同孔缝发育程度的页岩样品,设计并测试了变有效应力状态下变加载及卸载持续稳定时间对岩样渗透率的影响实验。结果表明:1)有效应力从5 MPa升至35 MPa时,微裂缝岩样和基块岩样渗透率分别降低了66.82%和27.19%,卸载过程中渗透率恢复率为74.73%和79.82%。页岩渗透率越低,有效应力滞后效应越显著;2)恒定有效应力加载持续稳定时间从2.5 h延长至10.0 h,应力敏感系数增加3.76%∼80.17%,且当有效应力较小时的时间效应更显著。研究认为,页岩组分及多尺度孔缝结构是导致其孔缝变形行为差异性的主因。基于实验研究结果,推荐页岩样品老化处理为6.0 h,提出了优化页岩储层敏感性评价实验方案和优化气井工作制度的建议。

Derivation of a second-order model for Reynolds stress using renormalization group analysis and the two-scale expansion technique

With the two-scale expansion technique proposed by Yoshizawa,the turbulent fluctuating field is expanded around the isotropic field.At a low-order two-scale expansion,applying the mode coupling approximation in the Yakhot-Orszag renormalization group method to analyze the fluctuating field,the Reynolds-average terms in the Reynolds stress transport equation,such as the convective term,the pressure-gradient-velocity correlation term and the dissipation term,are modeled.Two numerical examples：turbulent flow past a backward-facing step and the fully developed flow in a rotating channel,are presented for testing the efficiency of the proposed second-order model.For these two numerical examples,the proposed model performs as well as the Gibson-Launder （GL） model,giving better prediction than the standard k-ε model,especially in the abilities to calculate the secondary flow in the backward-facing step flow and to capture the asymmetric turbulent structure caused by frame rotation.

Thermal-Mechanical Simulation and Analysis on Structural Caused Package Induced Stress in Stacked Chip Scale Package

Stacked chip scale package(SCSP) attracts more and more attentions in advanced packages application with light weight,thin and small size,high reliability,low power and high storage capability.However,more and more physical and electrical issues being caused by package-induced stress in SCSP were reported recently.The effect of structural factors,including die thickness,die attach film thickness,die attach film type,and spacer size on package induced stress,was investigated.Analyses were given based on simulation results and provide important suggestion for package design.

Investigation of average growth stresses in Cr_2O_3 scales measured by a novel deflection method

The stress in the oxide film plays an important role to keep it intact so it is necessary to determine the stress in the oxide scale. Average growth stresses in Cr 2O 3 scales formed on Ni base alloy (Ni80Cr20) at 1?000?℃ in air were investigated by a novel deflection technique. It is found that the growth stress in the oxide scale is basically compressive and its average order is 100?MPa. The stress values are high for the thin scales and become low for thick scales after oxidized for 10?h. The planar stress distribution in metals is complex. It is both compressive and tensile at the beginning of oxidation procedure, and then become only tensile during further oxidation.

Clinicopathological features,psychological status,and prognosis of 33 patients with occult breast cancer

BACKGROUND Occult breast cancer(OBC)has traditionally been considered to be a carcinoma of unknown primary origin with a favorable prognosis and can be treated as stage II-III breast cancer.Due to the small number of cases and limited clinical experience,treatments vary greatly around the world and no standardized treatment has yet been established.AIM To investigate the clinicopathological features,psychological status and prognostic features of patients with OBC.METHODS The clinicopathological data of 33 OBC patients diagnosed and treated in the Affiliated Hospital of Xuzhou Medical University and Xuzhou Central Hospital from November 2015 to November 2022 were retrospectively analyzed.The psychological status of OBC patients was evaluated by the Self-rating Anxiety Scale and Self-rating Depression Scale.Patients’emotions,stress perception and psychological resilience were evaluated by the Positive and Negative Affect Schedule,the Chinese Perceived Stress Scale,and the Connor-Davidson Resilience Scale(CD-RISC),respectively.Patient survival was calculated using the Kaplan-Meier method,and survival curves were plotted for analysis with the log-rank test.Univariate and multivariate survival analyses were performed using the Cox regression model.RESULTS The 33 OBC patients included 32 females and 1 male.Of the 33 patients,30(91%)had axillary tumors,3(9%)had a neck mass as the primary symptom;18(54.5%)had estrogen receptor-positive tumors,17(51.5%)had progesterone receptor-positive tumors,and 18(54.5%)had Her-2-positive tumors;24(72.7%)received surgical treatment,including 18 patients who underwent modified radical mastectomy,1 patient who underwent breast-conserving surgery plus axillary lymph node dissection(ALND),and 5 patients who underwent ALND alone;12 patients received preoperative neoadjuvant therapy.All 30 patients developed anxiety and depression,with low positive affect scores and high negative affect scores,accompanied by a high stress level and poor psychological resilience.There were no differences in the psychological status of patients according to age,body mass index,or menopausal status.The overall survival and disease-free survival(DFS)of all the patients were 83.3%and 55.7%,respectively.Univariate analysis demonstrated that the initial tumor site(P=0.021)and node stage(P=0.020)were factors that may affect patient prognosis.The 5-year DFS rate of OBC patients who received radiotherapy was greater(P<0.001),while the use of different surgical methods(P=0.687)had no statistically significant effect on patient outcomes.Multivariate analysis revealed that radiotherapy(P=0.031)was an independent prognostic factor.Receiving radiotherapy had a significant effect on the CD-RISC score(P=0.02).CONCLUSION OBC is a rare breast disease whose diagnosis and treatment are currently controversial.There was no significant difference in the efficacy of other less invasive surgical procedures compared to those of modified radical mastectomy.In addition,radiotherapy can significantly improve patient outcomes.We should pay attention to the psychological state of patients while they receive antitumor therapy.

压力性损伤风险评估表对手术患者压力性损伤发生的护理效果分析

目的探究压力性损伤风险评估表对手术患者压力性损伤发生的护理效果影响。方法随机选取2020年1月-2021年12月潍坊市益都中心医院收治的200例外科手术患者为研究对象,以随机数表法分为观察组和对照组,每组100例。观察组采用Braden压力性损伤评估量表护理干预,对照组采用常规护理干预,对比两组患者的相关指标。结果观察组压力性损伤发生率为6.00%,低于对照组的17.00%,差异有统计学意义(χ^(2)=5.944,P<0.05)。观察组压力性损伤分期结果中,1期4例,2期1例,3期1例,4期0例,和对照组(1期3例,2期4例,3期10例,4期0例)相比,差异无统计学意义(P>0.05)。观察组护理满意度为97.00%,高于对照组87.00%,差异有统计学意义(P<0.05)。结论通过采用压力性损伤风险评估表护理干预,能够对压力性损伤患者的压力性损伤风险进行评估,也能够对患者的恢复情况进行判别。

孕期焦虑状态的影响因素分析

目的分析孕期焦虑状态的影响因素。方法选择2021年3月至2023年7月于潍坊市妇幼保健院建册并定期孕检的178例孕妇为研究对象,采用焦虑状态-特质问卷(STAI)、社会支持评定量表(SSRS)、妊娠压力量表调查孕期焦虑状态,并采用单因素、多因素logistic回归分析孕期焦虑状态的影响因素。结果178例孕妇中,41例存在孕期焦虑,占23.03%。单因素分析显示,孕期焦虑状态与学历、与丈夫的关系、与婆婆的关系、产前健康状况、对分娩的心理准备、孕妇学校听课次数及社会支持有关(P<0.05);多因素logistic回归分析显示,学历、与丈夫和婆婆的关系、产前健康状况、对分娩的心理准备、孕妇学校听课次数及社会支持是孕期焦虑状态的影响因素(P<0.05)。结论孕妇存在孕期焦虑状态的占比较高,且影响因素较多,应根据上述可控因素制订干预措施,以改善孕妇妊娠结局。

固体力学跨尺度计算若干问题研究

本文展示了固体力学领域跨尺度计算的若干问题和研究概况。(1)建立位错动力学与有限元耦合DDD-FEM的计算模型,实现了能够基于纳米尺度离散位错运动机制计算分析连续介质有限变形晶体塑性问题,提出微纳尺度(200 nm~10μm)晶体塑性流动应力解析公式,结合试验数据揭示了在无应变梯度下强度和变形的尺寸效应;(2)建立具有微相分离结构的纳米尺度粗粒化分子动力学模型CG-MD,计算获得聚脲材料在时域和频域下的存储模量和损耗模量,通过动态加载分析的DMA试验和超声波试验的数据验证,解决了连续介质尺度下微相分离高分子共聚物的设计难题;(3)通过数据驱动关联高分辨率的微米尺度CT影像和临床低分辨率的毫米尺度CT影像的特征值,建立了围关节松质骨小梁的等效模量和结构张量,为骨组织增材制造点阵结构设计和实现个性化骨缺损重建奠定了基础。

儿科手术患者术中获得性压力性损伤风险评估量表的构建及应用研究

目的 构建儿科手术患者术中获得性压力性损伤(IAPI)风险评估量表并探讨其应用效果。方法 选取2022年8月至2023年5月湖南省儿童医院106例儿科手术患者为研究对象,通过文献回顾和德尔菲专家函询,生成IAPI风险评估量表,将函询后生成的量表应用到临床,开展信效度检验及预测IAPI发生的效能。结果 两轮函询结果显示,专家积极性较高、权威程度较高、意见比较集中、一致性较高。最终量表包括手术时间、体位、美国麻醉医师协会分级、营养状态、体重指数、术中受压处皮肤情况、术前肢体活动、组织灌注8个条目,量表Cronbach’s α系数为0.705,分半信度为0.725,问卷水平内容效度指数为0.832,条目水平内容效度指数为0.805~1.000。使用Munro量表作为效标,术前、术中、术后评分的相关系数分别为0.377、0.415、0.513。量表预测IAPI发生的曲线下面积为0.810,灵敏度为70.8%、特异度为81.5%、临界值为13.5分。结论 构建的量表具有较高的权威性和科学性,可作为儿科手术患者IAPI风险的评估工具。

混凝土铺装层开裂对正交异性钢桥面疲劳性能劣化作用研究

为合理评估混凝土铺装层开裂对正交异性钢桥面板疲劳性能劣化的影响,开展足尺模型疲劳试验并进行数值仿真分析,得到铺装层开裂后钢桥面板典型易损细节疲劳应力,并提出疲劳应力增大系数量化分析裂缝尺寸对各细节疲劳应力的影响效应。结果表明:混凝土裂缝深度不超过其厚度20%时,正交异性钢桥面典型细节疲劳应力增幅很小;混凝土层正下方的横隔板-U肋-顶板及横隔板-U肋细节疲劳应力对混凝土裂缝长度、深度变化较敏感,混凝土开裂对横隔板弧形开口处及U肋圆弧处的影响较小;纵桥向裂缝对疲劳应力的影响比横桥向裂缝显著,且多裂缝会明显增大疲劳细节处应力水平,会加速桥面结构疲劳性能劣化,因此须设钢筋网阻滞裂缝扩展。