A Novel Tension Machine Promotes Bone Marrow Mesenchymal Stem Cell Osteoblastic and Fibroblastic Differentiation by Applying Cyclic Tension

Bone marrow mesenchymal stem cells (BMSCs) are intraosseous stem cells, and the effects of tensile strain on BMSC differentiation mediate several bone-related treatments. To study the response of BMSCs under tension, we designed and developed a small cellular tension instrument, iStrain. When iStrain applied tension on BMSCs, these cells exhibited convergence in the alignment direction and lengthening of the cell processes and cell body. Real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting demonstrated that iStrain-mediated cyclic tension promotes the differentiation of BMSCs toward osteogenesis and fibrogenesis. And the mRNA and protein expression of differentiation-related genes changes with the extension of tension time.

Spontaneous myogenic fasciculation associated with the lengthening of cardiac muscle in response to static preloading

Force enhancement is one kind of myogenic spontaneous fasciculation in lengthening preload striated muscles. In cardiac muscle, the role of this biomechanical event is not well established. The physiological passive property is an essential part for maintaining normal diastole in the heart. In excessive preload heart, force enhancement relative erratic passive properties may cause muscle decompensating, implicate in the development of diastolic dysfunction. In this study, the force enhancement occurrence in mouse cardiac papillary muscle was evaluated by a microstepping stretch method. The intracellular Ca2+ redistribution during occurrence of force enhancement was monitored in real-time by a Flou-3 (2 mM) indicator. The force enhancement amplitude, the enhancement of the prolongation time, and the tension–time integral were analyzed by myography. The results indicated that the force enhancement occurred immediately after active stretching and was rapidly enhanced during sustained static stretch. The presence of the force and the increase in the amplitude synchronized with the acquisition and immediate transfer of Ca2+ to adjacent fibres. In highly preloaded fibres, the enhancement exceeded the maximum passive tension (from 4.49 ± 0.43 N/mm2 to 6.20 ± 0.51 N/mm2). The occurrence of force enhancement were unstable in each static stretch. The increased enhancement amplitude combined with the reduced prolongation time to induce a reduction in the tension–time integral. We concluded that intracellular Ca2+-synchronized force enhancement is one kind of interruption event in excessive preload cardiac muscle. During the cardiac muscle in its passive relaxation period, the occurrence of this interruption affected the rhythmic stability of the cardiac relaxation cycle.

Experimental Wave Flume Tests in ROV-Wave Interaction Effects on the Line Tension for a Work Class ROV in Splash Zone

Integrity and stability of Remotely Operated Vehicle (ROV) when passing through the splash zone is one of the main concerns in the design of an ROV-umbilical system. Due to the lightweight nature of ROV in water, the umbilical experiences repetitive rapid transitions between slack and taut as the ROV travels through the splash zone. These rapid transitions induce tension spikes in the umbilical, namely snap forces, that can endanger the launch and recovery of an ROV. Therefore, it is important to ensure that the tension spikes do not exceed the safe working load of the umbilical. In this study, launch and recovery of a deep-water work class ROV are experimentally investigated using a 1:10 scaled ROV model through a series of wave flume tests. Different regular and irregular waves are generated in the flume while the ROV model is hung over the flume in four different positions. The tension time-history in the line is measured and recorded using a load cell at the top-end of the line. A simplified numerical model for launch and recovery of the ROV is developed and the numerical results are compared with the experimental ones. It is shown that the presented simplified model can be accurately used for analysis of launch and recovery of the ROV.

The static preload associated myogenic spontaneous fasciculation response in lengthening cardiac muscle

The passive tension force enhancement is one kind of myogenic spontaneous fasciculation in muscles. However, its physiological properties in cardiac fibres are not well known. In this study, mice cardiac papillary muscle spontaneous force enhancement was evaluated by micro stepping stretch method. The occurrence of spontaneous force and real time cardiac fibre Ca2+ redistribution was tranced by Flou-3 (2mM) indicator. Force enhancement amplitude, enhancement prolonging time, and tension–time integral were analysis by myograph analyser. The results indicated that the spontaneous force occurred immediately after the active stretch, rapidly enhanced during tolerating the sustained static stretch. The force occurrence and amplitude enhance synchronized with the Ca2+ recruitment and lightning transmitted to adjacent fibres. In high preload fibres, the enhancement was forceful to over its maximum passive tension (6.20 ± 0.51 N/mm2 to 4.49 ± 0.43 N/mm2). The force occurrences were unsteadiness in each stretch. The increased enhancement amplitude combining with the shortening prolonging time induced reduction of tension–time integral. We concluded that the intracellular Ca2+ synchronized force enhancement is one kind of interruption event in overloading cardiac fibres. This interruption occurred during the relaxation processing in cardiac muscle, therefore affect the rhythmic stability of cardiac relaxation-contraction cycle.

Effects of surface tension time-evolution for CCN activation of a complex organic surfactant

Time-evolving partitioning effects on surface tension and bulk water activity cancel out in Köhler predictions of CCN activation of mixed NAFA–NaCl particles.

Cardioprotective Effectiveness of a Combination of 2-Ethyl-6-Methyl-3-Hydroxypyridine Enantiomers and Rosuvastatin in a Model of Doxorubicin Cardiomyopathy

Aim. To study the cardioprotective effect of levorotatory ethylmethylhydroxypyridine malate enantiomer in combination with rosuvastatin on the model of doxorubicin cardiomyopathy.Material and methods. The research was conducted using 80 Langendorff perfused Wistar rat hearts (OOO “Kardioprotekt”, Saint-Petersburg) after a 3-day simulation of doxorubicin cardiomyopathy. The selection criteria for the evaluation of cardioprotective effect in the administration of ethylmethylhydroxypyridine derivatives and their combination with rosuvastatin were the indicators of left ventricular contractility, Tension-Time Index (t TTI), the diameter of cardiomyocytes.Results. During the experiment, it was found that the introduction of doxorubicin has a cardiotoxic effect, manifested through a decrease in the left ventricle contractility by 30–45% and an increase in the t TTI index by 4 times (“diastolic defect”). The introduction of a racemic mixture of ethylmethylhydroxypyridine malate at a dose of 93 mg/kg prevents the reduction of the left ventricle contractility and prevents the development of a “diastolic defect”, restraining the increase in the t TTI index by 32%, while the ethylmethylhydroxypyridine enantiomer at a dose of 93 mg/kg is more effective and its positive effect increases in combination with rosuvastatin at a dose of 0.4 mg/kg.Conclusion. The use of oxypyridine derivatives at doses of 50 mg/kg and 93 mg/kg, as well as their combination with rosuvastatin prevented the development of a “diastolic defect”. The highest effi ciency was revealed for the use of a combination of levorotatory ethylmethylhydroxypyridine malate enantiomer at a dose of 93 mg/kg with rosuvastatin at a dose of 0.4 mg/kg.

Mitigation for Hawser‘s Short Fatigue Life on The Study of The Fatigue Life Prediction of Hawser in Single Point Mooring (SPM) at Tuban Fuel Terminal

One of the vital components of SPM System is Mooring Hawser. Mooring Hawser is mooring lines that used to anchor the tanker ship that are berthed at Single Point Mooring (SPM) fuel terminal to loading or offloading the fuel oil. The incident of broken hawser unexpectedly due to short fatigue life that occurs on hawser when tanker ship that is anchored at SPM 150.000 DWT at Tuban Seas, East Java, Indonesia is the basis of this study for mitigation and replace of new hawser. This study calculates fatigue life of the hawser by using numerical simulation approach and Palmgren-Miner Methods. the hawser variation that conducted is only at the size of the outside diameter, namely: 0.144 m, 0.152 m, and 0.160 m. The material properties of the hawser in this study are Nylon Polyamide PA66. Numerical simulation consist of two steps: Hydrodynamics diffraction numerical simulation is used to obtain response (RAO) of tanker ship and SPM, and hydrodynamics time response numerical simulation is used to obtain effective hawser tension time history in 3600 second time simulation. By using the S-N Curve of Nylon Polyamide PA66 that is obtained from Jernej Klemenc, Andrej Wagner, and Matija Fadjiga (2011) as the basis to calculate fatigue life prediction of three variations in the outside diameter of the hawserwith Palmgren-Miner methods. The calculation result of new hawser fatigue life = 57.40536 Months or 4.718249 Years of Effective Berthing Time. The new hawser use outside diameter variation = 0.152 m to replace the previous hawser.

Extreme Value Estimation of Mooring Lines Top Tension

It is known that the mooring system of floating platforms responds non-linearly to environmental loads. Even though the wave-frequency excitation can be assumed as a Gaussian process, the line tension generally is not a Gaussian process due to the second-order slow-drift floater motions and the nonlinearities of the system itself. Distinct short-term time-domain analyses with the same wave spectrum excitation, i.e., distinct realizations of the response process, lead to a set of distinct values for the simulated individual maximum observed line tensions. Therefore, the ideal practice for estimating extreme tension values should be to perform a sufficiently large number of independent simulations along with an extreme statistical analysis considering the sample of the maximum line tension identified in each simulation. However, this process can be very time-consuming and cumbersome for everyday design applications. In this paper, the short-term line tension is assumed to be a non-Gaussian ergodic process. The extreme tension is then estimated based on the peaks sample of just a single simulated tension time-history. A number of known probability distributions are fitted to the peaks of the time series and classic order statistics theory is applied to determine the most probable extreme line tension corresponding to a specified short-time period (3-h) in order to identify the one with best performance. The proposed probability distribution models for the tension peaks are the 3-parameter Weibull distribution, the Weibull distribution fitted to the tail of the data (Weibull-tail) and the Shifted Generalized Lognormal Distribution (SGLD). The estimated extreme values are also prone to uncertainties due to time-domain simulation details. The effects of the major parameters in the dynamic analysis, such as simulation length and discretization level of the wave spectrum, are therefore investigated using several simulated mooring line tension time-histories. Furthermore, the effect of correlation between consecutive line tension peaks in the extreme values estimation is investigated through a Nataf transformation-based model for joint probability distribution for the peaks and the one step Markov chain condition. It is shown that this latter consideration leads to extreme value estimates that are invariably smaller than those obtained by standard order statistics. These estimates are also shown to be closer to the extreme estimates directly obtained from a sample of largest values taken from several distinct numerical simulations. Numerical examples cover two study cases for mooring lines belonging to FPSO (Floating, Production, Storage and Offloading) units to be installed in Brazilian waters.