ARTICLE | doi:10.20944/preprints202010.0359.v1
Subject: Materials Science, Biomaterials Keywords: β-iPP; simultaneous biaxial stretching; sequential biaxial stretching; structure evolution
Online: 19 October 2020 (08:07:59 CEST)
In this paper, the lamellar structural evolution and microvoids variations of β-iPP during the processing of two different stretching methods, sequential biaxial stretching and simultaneous biaxial stretching, were investigated in detail. It was found that different stretching methods led to significantly different lamellae deformation modes, and the microporous membranes obtained from the simultaneous biaxial stretching exhibited better mechanical properties. For the sequential biaxial stretching, abundant coarse fibers originated from the tight accumulation of the lamellae parallel to the longitudinal stretching direction, whereas the lamellae perpendicular to the stretching direction were easily deformed and separated. Those coarse fibers were difficult to be separated to form micropores during the subsequent transverse stretching process, resulting in a poor micropores distribution. However, for the simultaneous biaxial stretching, the β crystal had the same deformation mode, that is, the lamellae distributed in different directions were all destroyed, forming abundant microvoids and little coarse fibers formation.
ARTICLE | doi:10.20944/preprints201811.0526.v1
Subject: Physical Sciences, Applied Physics Keywords: Dancing, Muscle stretching exercise, Pliability
Online: 21 November 2018 (13:29:32 CET)
Objective: The purpose of this study is to compare the effects of stretching methods for flexibility, muscle activation, and pressure pain threshold in ballet dancers, and to suggest an effective stretching method. Methods: Thirty-three ballet dancers were randomized to a static stretching group (n=11), muscle energy technique stretching group (n=11), and vibration-assisted stretching group (n=11). The angle of hip joint extension in arabesque, the activation of rectus femoris in Devéloppé, and the pressure pain threshold on rectus femoris in sitting position were measured to compare the effects of different stretching methods. Results: Hip joint extension angles increased in all stretching methods (p<0.05), however, vibration-assisted stretching and muscle energy technique stretching were more effective than static stretching (p<0.05). The activation of the rectus femoris decreased in all groups (p<0.05), but the muscle energy technique stretching group and the vibration-assisted stretching group showed a significant decrease compared to the static stretching group (p<0.05). The pressure pain threshold showed significant improvement only in the static stretching group (p<0.05), and the vibration-assisted stretching group (p<0.05). Conclusion: Vibration-assisted stretching compared to static stretching and muscle energy technique stretching is a beneficial method for flexibility, muscle activation, and pressure pain threshold in ballet dancers.
ARTICLE | doi:10.20944/preprints201707.0065.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Biomedical Engineering, Cell Stretching, Mechanobiology.
Online: 24 July 2017 (10:04:57 CEST)
Cellular response to mechanical stimuli is an integral part of cell homeostasis. The interaction of the extracellular matrix with the mechanical stress plays an important role in cytoskeleton organisation and cell alignment. Insights from the response can be utilised to develop cell culture methods that achieve predefined cell patterns, which are critical for tissue remodelling and cell therapy. We report the working principle, design, simulation and characterisation of a novel electromagnetic cell stretching platform based on the double-sided axial stretching approach. The device is capable of introducing a cyclic and static strain pattern on a cell culture. The platform was tested with fibroblasts. The experimental results are consistent with the previously reported cytoskeleton reorganisation and cell reorientation induced by strain. The orientation of the cells is highly influenced by external mechanical cues. Cells reorganise their cytoskeleton to avoid external strain and to maintain intact extracellular matrix arrangements.
ARTICLE | doi:10.20944/preprints202109.0438.v1
Subject: Physical Sciences, Fluids & Plasmas Keywords: large eddy simulation; vortex stretching; subgrid model; isotropic turbulence
Online: 24 September 2021 (14:10:54 CEST)
In large eddy simulation (LES) of turbulent flows, the most critical dynamical processes to be considered by dynamic subgrid models to account for an average cascade of kinetic energy from the largest to the smallest scales of the flow is not fully clear. Furthermore, evidence of vortex stretching being the primary mechanism of the cascade is not out of the question. In this article, we study some essential statistical characteristics of vortex stretching and its role in dynamic approaches of modeling subgrid-scale turbulence. We have compared the interaction of subgrid stresses with the filtered quantities among four models using invariants of the velocity gradient tensor. This technique is a single unified approach to studying a wide range of length scales in the turbulent flow. In addition, it also provides a rational basis for the statistical characteristics a subgrid model must serve in physical space to ensure an appropriate cascade of kinetic energy. Results indicate that the stretching mechanism extracts energy from the large-scale straining motion and passes it onto small-scale stretched vortices.
REVIEW | doi:10.20944/preprints201807.0173.v1
Subject: Medicine & Pharmacology, Sport Sciences & Therapy Keywords: Static; Stretching; Post-Match; Soccer; Recovery; DOMS; Injury; Performance
Online: 10 July 2018 (11:53:41 CEST)
Soccer is the most played sport worldwide, with over 265 million participants. It is an incredibly demanding sport, with many different technical skills and physical loads placed on the body. This makes post-match recovery strategies amongst high level soccer players of great importance. The aim of this review is to summarize the existing literature on stretching for post-match recovery, examining its relation to injury prevention, Delayed Onset Muscle Soreness (DOMS), and performance. Scientific evidence of the highest quality and relevance was extracted and reviewed. Despite its common practice, evidence does not support static stretching as a modality to improve recovery post-match amongst soccer players. Larger trials with important outcome measures are needed to determine if a post-match stretching regimen to facilitate recovery exists.
ARTICLE | doi:10.20944/preprints201806.0250.v1
Subject: Materials Science, Polymers & Plastics Keywords: biaxial stretching; blend; polycarbonate; PMMA; phase inversion; surface hardness
Online: 15 June 2018 (10:51:13 CEST)
We investigated the structural evolution of the two-phase blends of polycarbonate (PC) and poly(methyl methacrylate) (PMMA) at various blend compositions by simultaneous biaxial stretching using optical microscopy and SEM observation. The spherical PMMA domains and PC matrix in 30/70 PC/PMMA were enlarged uniformly at all in-plane direction, while the anisotropic-shaped co-continuous structure in 50/50 PC/PMMA was deformed to crosshatched one by in-plane bimodal orientation. In 70/30 PC/PMMA, the phase inversion was found to occur by simultaneous biaxial stretching; i.e., the spherical PMMA domains were changed to crosshatched matrix by in-plane bimodal orientation due to coalescence of the PMMA domains during the stretching. Owing to the phase inversion, the surface hardness estimated by pencil hardness test became harder from 2B to 2H with increasing the strain from 1.0 to 2.0.
ARTICLE | doi:10.20944/preprints202210.0101.v1
Subject: Social Sciences, Accounting Keywords: Stretching; Foot Massage; Lavender Oil; High blood pressure; Stoke; Orem
Online: 9 October 2022 (02:19:28 CEST)
(1) Background: High blood pressure is one of the symptoms of stroke, the Self Care Deficit theory by Dorothea Orem focuses on a person's ability to care for himself independently so that the ability to maintain his health and well-being is achieved. There are currently 600 million hypertensive patients worldwide, of which 3 million die every year. Uncontrolled high blood pressure can lead to a 7-fold increase in the chances of stroke. The existence of this condition can be minimized in patients through several innovative interventions, one of which is foot massage. This study aims to determine the effectiveness of stretching and foot massage with lavender oil in stabilizing high blood pressure in stroke patients.(2) Methods: The method used in this research is descriptive. The subjects of this case study were selected according to the inclusion and exclusion criteria of the journal Evidence-Based. Subjects included intervention patients and control patients. Foot massage therapy with lavender oil is done 2 times a day for 10-15 minutes using the effleurage technique after showering in the morning and evening. Stretching is done 2 times a day every 10-15 minutes.(3) Results: The results of the analysis showed that there was a change in blood pressure after the application of stretching and foot massage with lavender oil. From the initial examination, the results showed that the blood pressure of 170/100 mmHg decreased to 140/90 mmHg and the pain scale decreased from 4 to 0.
Subject: Mathematics & Computer Science, Applied Mathematics Keywords: entropy generation; heat and mass transfer; stretching sheet; variable viscosity
Online: 11 September 2020 (08:05:17 CEST)
This work probes the combined effects of magnetic field and viscous dissipation on heat field and examine the second law analysis (entropy generation) in an electrically conducting fluid under the effect of wall mass transfer over continuous stretched non-isothermal surface with variable viscosity. The viscosity of the fluid is assumed to be an inverse linear function of temperature. The governing equation for the problem are changed to dimensionless ordinary differential equations by using similarity transformation and solved numerically by using Rung Kutta and Shooting technique. Velocity, concentration and temperature distribution are obtained and used to compute the entropy generation and the Bejan number in the flow field. The effect of variable viscosity, Schmidt number, Hartman and Reynolds number on the velocity, concentration, temperature, entropy generation and Bejan number are studied and discussed.
ARTICLE | doi:10.20944/preprints202104.0015.v1
Subject: Mathematics & Computer Science, Algebra & Number Theory Keywords: Heat transfer; Williamson fluid; Homotopy analysis method; exponential stretching; MHD; suction/injection
Online: 1 April 2021 (12:19:59 CEST)
This article investigates the features of heat and mass transfer for the steady two-dimensional Williamson nanofluid flow across an exponentially stretched surface depending on suction/injection. The boundary conditions incorporate the impacts of the Brownian motion and thermophoresis boundary. The analysis of heat transfer is carried out for the two cases of prescribed exponential order surface temperature (PEST) and prescribed exponential order heat flux (PEHF). The ongoing flow problem is mathematically modeled under the basic laws of motion and heat transfer. The similarity variables are allowed to transmute the governing equations of the problem into a similarity ordinary differential equation (ODEs). The solution of this reduced non-linear system of ODEs is supported by the Homotopy analysis method (HAM). The combination of HAM arrangements is acquired by plotting the h-curve. In order to evaluate the influence of several emergent parameters, the outcomes are presented numerically and are plotted diagrammatically as a consequence of velocity, temperature and concentration proles.
ARTICLE | doi:10.20944/preprints202012.0279.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Instrument Assisted Soft Tissue Mobilization; Muscle Stretching Exercises; Range of motion; Manual Therapy.
Online: 11 December 2020 (12:03:27 CET)
Background. Shoulder in CrossFit should have a balance between mobility and stability. Glenohumeral internal rotation deficit and posterior shoulder stiffness are risk factors for overhead shoulder injury. Objective. To determine the effectiveness of instrument assisted soft tissue mobilization and horizontal adduction stretch in CrossFit practitioners’ shoulders. Methods: Twenty-one regular CrossFitters were allocated to experimental (stretching with isometric contraction and instrument assisted soft tissue mobilization) or control group (instrument assisted soft tissue mobilization). Each session lasted 5 minutes, 2 days a week, over a period of 4 weeks. Shoulder internal rotation and horizontal adduction (digital inclinometer), and posterior shoulder stretch perception (Park scale) were evaluated. Shapiro-Wilk test was used to analyze the distribution of the sample. Parametric student's t-test was used to obtain the intragroup differences. The inter- and intra-rater differences were calculated using a repeated measures ANOVA. Results. Changes were found in the experimental group following intervention (p < 0.05), and when comparing baseline and follow-up assessments (p < .05) in all variables. Significant differences were found in the control group following intervention (p < 0.05), in right horizontal adduction and left internal rotation. When comparing perception of internal rotation and horizontal adduction in both groups in the three assessments significant differences were found. Conclusions. Instrument assisted soft tissue mobilization can improve shoulder horizontal adduction and internal rotation. An instrument-assisted soft tissue mobilization technique yields the same results alone as those achieved in combination with post-isometric stretch with shoulder adduction.
ARTICLE | doi:10.20944/preprints201910.0297.v1
Subject: Materials Science, Polymers & Plastics Keywords: polyelectrolytes; charge regulation; charge fluctuations; weak polyelectrolyte; annealed polyelectrolyte; monte carlo simulation; semi-grand canonical ensemble; binding equilibria; conformational equilibria; constant ph ensamble; stretching; scaling law
Online: 27 October 2019 (10:01:16 CET)
This work addresses the role of charge regulation (CR) and the associated fluctuations in the conformational and mechanical properties of weak polyelectrolytes. Due to CR, changes in the pH-value modifies the average macromolecular charge and conformational equilibria. A second effect is that, for a given average charge per site, fluctuations can alter the intensity of the interactions by means of correlation between binding sites. We investigate both effects by means of Monte Carlo simulations at constant pH-value, so that the charge is a fluctuating quantity. Once the average charge per site is available, we turn off the fluctuations by assigning the same average charge to every site. A constant charge MC simulation is then performed. We make use of a model which accounts for the main fundamental aspects of a linear flexible polyelectrolyte i.e. proton binding, angle internal rotation, bond stretching and bending. Steric excluded volume and differentiated treatment for short-range and long-range interactions are also included in the model. It can be regarded as a kind of "minimal'' model in the sense that contains a minimum number of parameters but still preserving the atomistic detail. It is shown that, if fluctuations are activated, gauche state bond probabilities increase, and the persistence length decreases, so that the polymer becomes more folded. Macromolecular stretching is also analyzed in presence of CR (the charge depends on the applied force) and without CR (the charge is fixed to the value at zero force). The analysis of the low force scaling behavior concludes that Pincus exponent becomes pH-dependent. Both with and without CR, a transition from 1/2 at high pH-values (phantom chain) to 3/5 to low pH-values (Pincus regime), is observed. Finally, the intermediate force stretching regime is investigated. It is found that CR induces a moderate influence in the force-extension curves and persistence length (which in this force regime becomes force-dependent). It is thus concluded that the effect of CR on the stretching curves is mainly due to changes in the average charge at zero force. It is also found that, for the cases studied, the effect of steric excluded volume is almost irrelevant compared to electrostatic interactions.