Effect of pulsed hydrodynamic influences on blood cells in vitro and in vivo

(Presented by Academician of the Academy of Medical Sciences of the USSR A. N. Klimov.) Translated from Byulleten' Éksperimental'noi i Biologii i Meditsiny, Vol. 110, No. 12, pp. 604–606, December, 1990.     

Single-equation models for the tear film in a blink cycle: realistic lid motion.

We consider model problems for the tear film over multiple blink cycles that utilize a single equation for the tear film; the single non-linear partial differential equation that governs the film thickness arises from lubrication theory. The two models that we consider arise from considering the absence of naturally occurring surfactant and the case when the surfactant is strongly affecting the surface tension. The film is considered on a time-varying domain length with specified film thickness and volume flux at each end; only one end of the domain is moving, which is analogous to the upper eyelid moving with each blink. Realistic lid motion from observed blinks is included in the model with end fluxes specified to more closely match the blink cycle than those previously reported. Numerical computations show quantitative agreement with in vivo tear film thickness measurements under partial blink conditions. A transition between periodic and non-periodic solutions has been estimated as a function of closure fraction and this may be a criterion for what is effectively a full blink according to fluid dynamics.     

Investigation of Adhesion Properties of Tire—Asphalt Pavement Interface Considering Hydrodynamic Lubrication Action of Water Film on Road Surface

To obtain the tire–pavement peak adhesion coefficient under different road states, a field measurement and FE simulation were combined to analyze the tire–pavement adhesion characteristics in this study. According to the identified texture information, the power spectral distribution of the road surface was obtained using the MATLAB Program, and a novel tire hydroplaning FE model coupled with a textured pavement model was established in ABAQUS. Experimental results show that here exists an “anti-skid noncontribution area” for the insulation and lubrication of the water film. Driving at the limit speed of 120 km/h, the critical water film thickness for the three typical asphalt pavements during hydroplaning was as follows: AC pavement, 0.56 mm; SMA pavement, 0.76 mm; OGFC pavement, 1.5 mm. The road state could be divided into four parts dry state, wet sate, lubricated state, and ponding state. Under the dry road state, when the slip rate was around 15%, the adhesion coefficient reached the peak value, i.e., around 11.5% for the wet road state. The peak adhesion coefficient for the different asphalt pavements was in the order OGFC > SMA > AC. This study can provide a theoretical reference for explaining the tire–pavement interactions and improving vehicle brake system performance.     

利宁凝胶联合丙泊酚用于无痛流产术效果观察

目的观察利宁凝胶联合丙泊酚用于无痛流产术中的效果。方法将600例早孕妇女随机分为观察组和对照组各300例,观察组采用利宁凝胶宫颈表面麻醉联合丙泊酚静脉麻醉,对照组仅用丙泊酚静脉麻醉。观察两组宫颈松弛度、肢体或身体扭动、呻吟下腹痛、手术时间、麻醉用药量、出血量。结果观察组宫颈松弛度明显好于对照组,疼痛发生率及平均手术时间、平均出血量明显低于对照组,P<0.05或0.01。结论利宁凝胶联合丙泊酚应用于无痛流产麻醉镇痛效果好,且较为安全,值得临床借鉴。     

冲击载荷作用下蛋白质水溶液润滑吸附膜的生长特性

目的研究蛋白质水溶液挤压润滑条件下材料表面蛋白质吸附膜的动态生长特性及其影响因素。方法利用光干涉技术测量球盘点接触在循环冲击条件下BSA蛋白质水溶液的吸附膜厚的生长过程,并研究冲击载荷、冲击次数、材料表面性质对BSA水溶液的吸附成膜特性的影响。结果动态条件下蛋白质润滑吸附膜要比静态工况下的升高很多,冲击条件下蛋白质吸附膜不断生长,并最终达到稳定厚度。小载荷和疏水材料表面有利于蛋白质润滑吸附膜的生长。钢表面极易形成较厚吸附膜,而陶瓷表面吸附膜厚较低。结论针对冲击载荷作用下蛋白质水溶液润滑吸附膜的生长特性研究对人工关节磨损、松动等的治疗、预防具有一定的临床指导意义。     

Wear Behavior of Fiber Laser Textured TiN Coatings in a Heavy Loaded Sliding Regime

In heavy loaded mating components, such as sliders and sliding bearings, guaranteeing the efficiency of lubricant films for long times during severe service conditions is very complicated. In this work, the benefits deriving from the use of fiber laser sources for surface texturing of very thin TiN coatings in severe wear working conditions were demonstrated. Evaluations of the laser textured dimples shape, geometry and density are given. Wear performance of the fiber laser textured surfaces was evaluated in discontinuous oil lubricated conditions with a flat contact. High normal load and low sliding speed were applied. Comparison tests were also performed on commercial TiN and WC/C coatings. In terms of average wear volume and maximum wear depth, Laser Surface Texturing of TiN provided respectively a 70% and a 45% reduction if compared to plain TiN. If compared to WC/C the wear resistance gains were lower but LST TiN maintained such benefits for longer wear runs. SEM analysis also revealed that the laser interaction provided a localized thermal cracking to the TiN coating. However, the sliding action caused very limited and localized coating fragmentation or delamination.     

Escherichia coli biofilm formation and dispersion under hydrodynamic conditions on metal surfaces

The aim of this study was to analyze the impact of hydrodynamic forces on the multiplication of E. coli, and biofilm formation and dispersion. The experiments were provided in a flow chamber simulating a cleaning-in-place system. Biofilm biomass was measured using a crystal violet dye method. The results show that hydrodynamic forces affect not only biofilm formation and dispersion but the multiplication of E. coli in the first place. We found more biofilm biomass on the rough surface than on the smooth one. The results of the biofilm formation test show that laminar flow promotes the biofilm growth over 72 h, meanwhile turbulent flow after 48 h causes decrease in biomass. The results of the biofilm dispersion test, in contrast, show that laminar flow removed less biofilm from both materials that turbulent flow did. Therefore, taking into account these findings in cleaning-in-place technology can substantially reduce E. coli multiplication and biofilm formation.     

The Clitoris—An Appraisal of its Reproductive Function During the Fertile Years: Why Was It,and Still Is,Overlooked in Accounts of Female Sexual Arousal

Stimulating the clitoris activates the brain to instigate changes in the female genital tract, namely, the enhancement of vaginal blood flow that increases vaginal luminal pO₂, vaginal transudate (lubrication) facilitating painless penile penetration and partial neutralization of the basal luminal acidic pH, vaginal tenting, and ballooning delaying sperm transport and allowing semen de-coagulation and capacitation (sperm activation) factors to act until arousal ends (often by orgasm induction). All these genital changes taken together are of major importance in facilitating the possibility of reproductive success (and thus gene propagation) no matter how or when the clitoris is stimulated—they reveal its overlooked reproductive function. Of course, also commensurate with these changes, is its activation of sexual pleasure. The clitoris thus has both procreative (reproductive) and recreative (pleasure) functions of equal importance. Clitoridectomy creates not only sexual disability but also a reproductive disability. Clin. Anat. 32:136–145, 2019. © 2019 Wiley Periodicals, Inc.