髌骨软骨拉伸应力松弛蠕变实验研究

目的　研究正常国人 8具新鲜尸体髌骨软骨的力学性质 ,为临床提供生物力学参数。方法　对正常国人新鲜尸体髌骨软骨一维拉伸力学性能和拉伸应力松弛、蠕变粘弹性力学性质进行实验研究。结果　获得了髌骨软骨一维拉伸的破坏载荷、伸长比、张应力、张应变等测试结果 ,以多项式用最小二乘法对拉伸实验数据进行拟合 ,得出了半月板的应力 -应变关系表达式和应力 -应变曲线。还得出了应力松弛、蠕变数据、曲线和归一化应力松弛函数、归一化蠕变函数数据、曲线。对实验数据以最小二乘法进行处理 ,得出了G(t)表达式 ,根据准线性理论得出了半月板的松弛函数K(λ、t)=G(t)T(e) (λ)的表达式。结论　髌骨软骨单向拉伸最大载荷为 3 8.5 4± 4.1 8N ,伸长比为 1 .3 1 2± 0 .0 1 8,张应力为 6.65± 0 .83MPa ,应变为 3 4.0± 3 .6%。应力松弛曲线是以对数关系变化的 ,蠕变曲线是以指数关系变化的     

胫股关节半月板松弛函数的实验研究

目的　研究正常国人急性外伤致死的成人新鲜尸体半月板的力学性质 ,为临床提供生物力学参数。方法　对 5具正常国人新鲜尸体胫股关节半月板的一维拉伸力学性能和拉伸应力松弛粘弹性力学性质进行测试。结果　得出了半月板一维拉伸的破坏载荷、伸长比、Lagrange张应力、La grange张应变等实验数据。以多项式用最小二乘法对拉伸实验数进行拟合 ,得出了半月板的应力 应变关系表达式和应力 应变曲线。获得了半月板应力松弛曲线和数据 ,归一化应力松弛函数数据和曲线 ,以及半月板的G(t)表达式。根据准线性理论还得出了髌骨软骨的松弛函数K(λ、t) =G(t)T(e) (λ)的表达式。结论　髌骨软骨单向拉伸最大载荷为 40± 3N ,伸长比为 1 .3 69± 0 .0 48,张应力为 7.2 7± 0 .5 9MPa ,应变为 43 .8± 6.6%。应力松弛主要发生在 1 2 0 0s以内。应力松弛曲线是以对数关系变化的。     

肩髋膝关节软骨生物力学特性

研究了正常国人急性外伤致死的成人新鲜尸体肩髋膝关节软骨的力学性质.以一维拉伸的方法得出了肩髋膝关节软骨的破坏载荷、伸长比、Lagrange应力、Cauchy应变等.用最小二乘法对拉伸实验数据进行拟合,得出了肩髋膝关节的应力-应变关系表达式和应力-应变曲线;对肩髋膝关节软骨进行一维拉伸应力松弛实验,得出了应力松弛以及归一化后应力松弛函数数据和曲线,应用最小二乘法得出了肩髋膝关节的G(t).并对实验结果进行分析讨论.     

人眼角膜黏弹性实验研究

对正常国人6具新鲜尸体8个眼角膜标本进行单向拉伸实验和拉伸应力松弛、蠕变实验。得出了人眼角膜拉伸最大载荷、伸长比、张应力、应变、拟弹性模量。还得出了人眼角膜的应力松弛、蠕变数据和曲线。对应力松弛、蠕变实验数据进行归一化处理,得出了归一化应力松弛函数、蠕变函数及曲线。对应力松弛、蠕变实验数据进行回归分析,得出了回归系数。对人眼角膜应力、应变数据以多项式,用最小二乘法进行拟合,得出了其应力应变关系公式及曲线,建立了人眼角膜的松弛函数k(λ,t)=G(t)T(e)λ的表达式,得出了一些重要结论。     

人颈椎后纵韧带黏弹性实验研究

研究了正常国人8具新鲜尸体颈椎后纵韧带C1-C4、C4-T1的黏弹性力学性质.对C1-C4、C4-T1段后纵韧带进行拉伸应力松弛、蠕变实验.得出了C1-C4、C4-T1后纵韧带的应力松弛、蠕变数据和曲线.对应力松弛、蠕变数据进行归一化处理,得出了归一化应力松弛函数蠕变函数及曲线.对实验数据进行回归分析,得出了回归系数.还对后纵韧带C1-C4段、C4-T1段试样进行单向拉伸实验,得出了后纵韧带的拉伸破坏载荷、伸长比、拉应力、拉应变等,对应力应变数据以多项式,用最小二乘法进行拟合,得出其应力应变关系公式及曲线.构建了后纵韧带的松弛函数K(λ、t)=G(t)T(e)(λ)表达式,对实验结果进行分析讨论.     

去势大鼠所致骨质疏松对骨生物力学性质影响的实验研究

研究了正常大鼠和去势(摘除卵巢)所致大鼠骨质疏松大鼠骨的弯曲、拉伸实验和应力松弛、蠕变实验。选用280～320g,4～5月龄wistar雌性大鼠50只,随机分为正常对照组25只,模型组25只。对模型组大鼠于0周摘除其卵巢。对正常对照组和模型组大鼠饲养14周,以腹主动脉放血法处死大鼠。取大鼠股骨进行弯曲实验,取肱骨进行拉伸实验,还对大鼠股骨进行应力松弛蠕变实验。得出了正常对照组和模型组大鼠肱骨拉伸力学性能指标,正常组和对照组大鼠肱骨弯曲力学性能指标,还得出了正常组和模型组大鼠股骨应力松弛、蠕变实验数据和典线。对应力松弛、蠕变实验数据进行归一化处理,得出了归一化应力松弛函数,归一化蠕变函数及曲线。对实验数据进行回归分析,得出了回归系数和G(t)、J(t)表达式。实验结果表明:模型组各项力学性能指标均显著低于正常对照组。     

小儿肠套叠肠管与人阑尾归一化应力松弛函数蠕变函数

本文对小儿肠管及套入部分肠管和人阑尾进行了生物力学实验研究。得出了单向拉伸破坏时的应力、应变、伸长比λ，还得出了小儿正常肠管及肠套叠肠管、人阑尾应力松弛、蠕变曲线还得出正常肠管、人阑尾应力松弛、蠕变函数及曲线。并对小儿肠套叠的发病机理以生物力学的观点进行分析讨论，对人阑尾和小儿肠管的力学性质进行比较     

模拟失重对雄性大鼠骨流变特性的测试

目的研究模拟失重对大鼠承重骨流变特性的影响,为航天医学提供模拟失重动物骨流变参数。方法30只Wistar雄性大鼠,随机分为正常对照组15只和头低位30°尾吊组(失重模型组)15只。实验第28天时取两组动物股骨进行压缩应力松弛、蠕变实验。结果得出了正常对照组和失重模型组大鼠股骨压缩应力松弛、蠕变数据和曲线,得出了两组大鼠股骨的归一化应力松弛函数,归一化蠕变函数与曲线,以一元线性回归分析的方法处理实验数据,得出了回归系数a、b与c、d值和归一化应力松弛函数G(t)、归一化蠕变函数J(t)表达式,还得出了两组大鼠股骨应力松弛、蠕变与时间的变化规律。结论失重模型组大鼠股骨应力松弛、蠕变量低于正常对照组。     

骨性关节炎对膝关节软骨粘弹性影响实验研究

研究了正常国人新鲜尸体膝关节软骨和骨性关节炎膝关节软骨的粘弹性力学性质.对正常和病态膝关节软骨进行一维拉伸应力松弛、蠕变实验,得出了应力松弛、蠕变实验数据和曲线,以回归分析的方法处理应力松弛、蠕变实验数据,得出了归一化应力松弛函数、归一化蠕变函数表达式.以冯元桢教授的准线性理论得出了正常组和病态组膝关节软骨松弛函数表达式,并对实验结果进行了分析讨论.     

桡动脉血管生物力学性质实验研究

研究了正常国人新鲜尸体挠动脉血管的一维拉伸力学性质，得出了桡动脉血管的破坏载荷、伸长比、Lagrange张应力、Lagrange张应变、Euler应力等数据。以多项式用最小二乘法对实验数据进行拟合，得出了桡动脉的应力——应变关系表达式及曲线。得出了一些结论。     

Relaxation of tetanized canine tracheal smooth muscle

As is the case for striated muscle, relaxation in smooth muscle has been little studied and is less understood. We report studies of load bearing capacity during relaxation of airway smooth muscle. The model employed was the canine tracheal smooth muscle (TSM). The effect of load on the time course of relaxation was analyzed either by comparing afterloaded contractions against various loads or by imposing abrupt alterations in load (load clamps). Unlike mammalian cardiac muscle in which relaxation was reported sensitive to loading conditions, relaxation in TSM was largely independent of loading conditions. In this it resembled frog heart muscle and mammalian cardiac muscle cells without functioning calcium sequestering systems. This type of relaxation which is not influenced by manipulation of loading conditions, has been termed inactivation-dependent relaxation. It appears to operate in muscle tissue in which the calcium sequestering apparatus is poorly developed and the dissipation of activation (removal of activating calcium, detachment of force generating sites, etc.) appears to be the rate limiting step during relaxation.     

Broadband Dielectric Relaxation Spectroscopy of Functionalized Biobased Castor Oil Copolymer Thermosets

Novel biorenewable copolymer thermosets are successfully synthesized by the ring‐opening metathesis polymerization (ROMP) of norbornenyl‐functionalized castor oil (NCO) and norbornenyl‐functionalized castor oil alcohol (NCA) with controlled amounts of 0.8 and 1.8 norbornene rings per fatty acid chain, respectively. The NCO and NCA monomers are mixed in different concentrations and simultaneously polymerized via ROMP using Grubbs catalyst. Broadband dielectric relaxation spectroscopy (BDRS) is used to investigate the molecular dynamics of the fully cured copolymer thermosets over a wide range of frequencies (5 × 10^?2 to 0.5 × 10⁷ Hz) at different constant temperatures (?70 to 125 °C). Four phenomena, namely α‐, β‐, and γ‐relaxation processes and ionic conductivity are observed for all the measured samples.

     

Intragastric pressure and receptive relaxation in the rat

Intragastric pressure has been measured in the rat under conditions of free feeding and gastric counterinfusion during free feeding. Gastric relaxation resulting in a plateauing of pressure was demonstrated in both cases. While counterinfused animals had additional volume entering the stomach via a direct route that bypassed pregastric oropharyngeal sensors, the relative pressure did not increase over the not-counterinfused animals. This data suggests that there is not a precise metering and gradation of vagal messages arising from deglutition. The stomach musculature is able to relax to a greater degree than that indicated by deglutition signals alone. The nature of such additional relaxation is not known.     

Progressive versus self-control relaxation to reduce spontaneous bleeding in hemophiliacs

Motivated by previous reports of relaxation successes with hemophiliacs, we sought to isolate the value of relaxation strategies. The effects of progressive and self-control relaxation on spontaneous bleeding and collateral symptoms were tested with seven hemophiliacs in a combined multiple-baseline partial-crossover design. Following 6 or 12 weeks of training in either or both relaxation methods, there was no strong evidence that the treatment affected bleeding or perceived pain in these subjects. These disappointing results were obtained despite within-session physiological evidence of relaxation induction and self- and spouse reports of faithful relaxation practice. The present results failed to replicate previous findings, cast doubt on the stress theory of spontaneous bleeding, and recommend further research to clarify the role of psychological interventions for hemophiliacs.     

The effects of nonconcurrent and concurrent relaxation training on cardiovascular reactivity to a psychological stressor

Eight patients in a cardiac rehabilitation program, after exposure to two psychological stressors approximately equivalent with respect to cardiovascular reactivity, were given nonconcurrent progressive muscle relaxation training and retested for reactivity. They were then provided with relaxation training concurrently with one of the stressors and exposed again to the two stressors. No significant effects for nonconcurrent progressive muscle relaxation training were detected. Concurrent training, in contrast, produced reductions in both systolic and diastolic blood pressure. Reductions resulting from training on the target stressor showed little tendency to generalize to the nontarget stressor; the discrimination was particularly well defined for systolic blood pressure. We conclude that muscle relaxation techniques are maximally effective in reducing reactivity to psychological stressors when relaxation training is provided concurrently with the stressor. Our findings further suggest that to inculcate the relaxation response reliably across different situations, specific training to enhance generalization may be needed.     

Lithium compartmentation in brain by 7Li MRS: effect of total lithium concentration

In previous work at 4.7 T, the individual components of biexponential ⁷Li transverse (T₂) spin relaxation in rat brain in vivo were tentatively identified with intra‐ and extracellular Li. The goal in this work was to estimate Li's compartmental distribution as a function of total Li concentration in brain from the biexponential decays. Here a localized, biexponential ⁷Li T₂ MR spin‐relaxation study with isotopically enriched ⁷LiCl is reported in rat brain in vivo at 7 T. Additionally, a simple linear interpolation using the biexponential T₂ values to estimate intracellular Li from individual monoexponential T₂ decays was assessed. Intracellular T₂ was 14.8 ± 4.3 ms and extracellular T₂ was 295 ± 61 ms. The fraction of intracellular brain Li ranged from 37.3 to 64.8% (mean 54.5 ± 6.7%) and did not correlate with total Li concentration. The estimated intracellular Li concentration ranged from 47 to 80% (mean 68.3 ± 8.5%) of the total brain Li concentration and was highly correlated with it. The monoexponential estimates of the intracellular‐Li fractions and derived concentrations averaged about 15% higher than the corresponding biexponential estimates. This work supports the previous conclusion that a large fraction of Li in the brain is within the intracellular compartment. Copyright © 2013 John Wiley & Sons, Ltd.     

Effects of Progressive Relaxation and Classical Music on Measurements of Attention, Relaxation, and Stress Responses

The present experiment examined relaxation using different experimental conditions to test whether the effects of individual elements of relaxation could be measured, whether specific effects were revealed, or whether relaxation resulted from a generalized relaxation response. Sixty-seven normal, male volunteers were exposed to a stress manipulation and then to one of two relaxation (Progressive Relaxation, Music) or control (Attention Control, Silence) conditions. Measurements of attention, relaxation, and stress responses were obtained during each phase of the experiment. All four groups exhibited similar performance on behavioral measures of attention that suggested a reduction in physiological arousal following their relaxation or control condition, as well as a decreased heart rate. Progressive Relaxation, however, resulted in the greatest effects on behavioral and self-report measures of relaxation, suggesting that cognitive cues provided by stress management techniques contribute to relaxation.     

葛根素对自发性高血压大鼠肠系膜动脉舒张功能的影响

目的　探究葛根素对自发性高血压大鼠肠系膜动脉舒张功能的影响。 方法　20只自发性高血压大鼠随机分为5组：高血压组,卡托普利组,葛根素低、中、高剂量组,每组4只,另外4只WKY作为正常对照组。于给药前、给药8周后测量体重和血压,检测血清中NO和血浆中ET-1含量,分离肠系膜三级动脉做HE染色并计算管壁厚度/管腔半径（WT/LR）。利用离体血管压力直径测定仪检测葛根素对内皮完整和去内皮动脉环的舒张效应,并观察内皮依赖性途径阻滞剂和非内皮依赖性途径阻滞剂孵育后,葛根素对动脉环舒张作用的影响。 结果　与高血压组相比,葛根素低、中、高剂量组的收缩压差值和舒张压差值均降低。葛根素高剂量组血清NO含量下降、血浆ET-1含量升高。葛根素中、高剂量组肠系膜三级动脉WT/LR均下降。葛根素对内皮完整和去内皮的动脉环均有浓度依赖性舒张作用,但内皮完整动脉环舒张作用更强。内皮依赖性通路阻滞剂和非内皮依赖性通路阻滞剂孵育后,葛根素的舒张效应均下降。 结论　葛根素对自发性高血压大鼠肠系膜动脉的舒张效应同时具备内皮依赖性和非内皮依赖性。其内皮依赖性途径通过NO-sGC-cGMP信号通路途径来实现的,同时也与促进前列腺类物质释放有关。葛根素非内皮依赖性途径可能是与血管平滑肌上K+通道开放有关。     

脂肪间充质干细胞早期干预对野百合碱诱发的肺动脉高压大鼠肺小动脉功能的影响

 目的：观察脂肪间充质干细胞(ADMSCs)早期干预对野百合碱(MCT)诱发的大鼠肺动脉高压(PAH)进程中肺小动脉功能的影响。方法：采用SD大鼠腹股沟皮下脂肪,经胶原酶消化法分离培养ADMSCs。雄性SD大鼠90只,随机分为正常对照组、PAH组和ADMSCs早期干预组(ADMSCs-EI组)。一次性腹腔注射MCT 40 mg/kg建立PAH动物模型。ADMSCs-EI组于MCT注射后1周,经左颈外静脉一次性给予ADMSCs(1×106)。分别于ADMSCs移植后1、2、3周,右心导管法测定大鼠的肺动脉平均压(MPAP),并采用离体血管张力法检测大鼠肺小动脉的内皮依赖性舒张(EDdR)、非内皮依赖性舒张(EDiR)以及收缩功能(VCF)。收缩或舒张的敏感性用pD2值表示。结果：与对照组比较,腹腔注射MCT后2周,PAH组大鼠肺小动脉EDdR明显减弱;同时,与PAH组比较,ADMSCs早期移植后1周,ADMSCs-EI组大鼠肺小动脉EDdR明显增强（均P<005）。与对照组比较,腹腔注射MCT后3、4周,PAH组大鼠MPAP显著升高,肺小动脉EDdR和EDiR显著减弱;同时,与PAH组比较,ADMSCs早期移植后2、3周,ADMSCs-EI组大鼠MPAP显著降低,肺小动脉EDdR和EDiR显著增强（均P<005）;但是,VCF在3组间均无显著差异（P>005）。结论： ADMSCs早期干预可以明显改善受损的肺小动脉EDdR及EDiR,并有效地降低MCT诱发的PAH大鼠的肺动脉压力。