Finite deformation and fractional order viscoelasticity of an auxetic foam

Auxetic foams exhibit novel mechanical properties due to their unique microstructure for improved energy-absorption and cavity expansion applications that have fascinated the scientific community since their inception. Given the advancements in material processing and performance of polymer open cell auxetic foams, there is a strong desire to fully understand the nonlinear rate-dependent deformation of these materials. The influence of nonlinear compressibility is introduced here along with relaxation effects to improve model predictions for different stretch rates and finite deformation regimes. The viscoelastic behavior of the material is analyzed by comparing fractional order and integer order calculus models. All results are statistically validated using maximum entropy methods to obtain Bayesian posterior densities for the hyperelastic, auxetic, and viscoelastic parameters. It is shown that fractional order viscoelasticity provides [Formula: see text]–[Formula: see text] improvement in prediction over integer order viscoelastic models when the model is calibrated at higher stretch rates where viscoelasticity is more significant.

Investigation of Crystallization and Relaxation Effects in Coarse-Grained Polyethylene Systems after Uniaxial Stretching

In this study, we investigate the thermo-mechanical relaxation and crystallization behavior of polyethylene using mesoscale molecular dynamics simulations. Our models specifically mimic constraints that occur in real-life polymer processing: After strong uniaxial stretching of the melt, we quench and release the polymer chains at different loading conditions. These conditions allow for free or hindered shrinkage, respectively. We present the shrinkage and swelling behavior as well as the crystallization kinetics over up to 600 ns simulation time. We are able to precisely evaluate how the interplay of chain length, temperature, local entanglements and orientation of chain segments influences crystallization and relaxation behavior. From our models, we determine the temperature dependent crystallization rate of polyethylene, including crystallization onset temperature.

Induction of Relaxation by Autonomous Sensory Meridian Response

Background: Autonomous sensory meridian response (ASMR) is used by young people to induce relaxation and sleep and to reduce stress and anxiety; it comprises somatosensation caused by audiovisual stimuli (triggers) that lead to positive emotions. Auditory stimuli play the most important role among the triggers involved in ASMR and have been reported to be more triggering than visual stimuli. On the other hand, classical music is also known to have a relaxing effect. This is the first study to clarify the difference in brain activation associated with relaxation effects between ASMR and classical music by limiting ASMR to auditory stimulation alone.Methods: Thirty healthy subjects, all over 20 years of age, underwent fMRI while listening to ASMR and classical music. We compared the differences in brain activation associated with classical music and ASMR stimulation. After the experiment, the subjects were administered a questionnaire on somatosensation and moods. After the experiment, the participants were asked whether they experienced ASMR somatosensation or frisson. They were also asked to rate the intensity of two moods during stimulation: “comfortable mood,” and “tingling mood”.Result: The results of the questionnaire showed that none of the participants experienced any ASMR somatosensation or frisson. Further, there was no significant difference in the ratings given to comfort mood, but there was a significant difference in those given to tingling mood. In terms of brain function, classical music and ASMR showed significant activation in common areas, while ASMR showed activation in more areas, with the medial prefrontal cortex being the main area of activation during ASMR.Conclusion: Both classical music and the ASMR auditory stimulus produced a pleasant and relaxed state, and ASMR involved more complex brain functions than classical music, especially the activation of the medial prefrontal cortex. Although ASMR was limited to auditory stimulation, the effects were similar to those of listening to classical music, suggesting that ASMR stimulation can produce a pleasant state of relaxation even if it is limited to the auditory component, without the somatic sensation of tingling. ASMR stimulation is easy to use, and appropriate for wellness purposes and a wide range of people.

Exposure to virtual nature: the impact of different immersion levels on skin conductance level, heart rate, and perceived relaxation

It is generally accepted that natural environments reduce stress and improve mood. Since access to natural environments is sometimes limited, virtual natural environments, especially monoscopic 360° nature videos, offer a viable alternative. However, it remains unclear whether presenting monoscopic 360° nature videos via a head-mounted display (HMD) or a PC monitor results in larger relaxation effects. Therefore, this study examined whether a monoscopic 360° beach video presented with an HMD is significantly more relaxing than the same video presented via a PC screen, or no video at all (control condition), in altering skin conductance level (SCL), heart rate (HR), and perceived relaxation. Overall, 102 adults (40.2% females, age range 19–62 years) participated in a counterbalanced, randomized, controlled, within-subject experiment. All participants were subjected to three stressors comprising different mental arithmetic tasks, followed by three different recovery phases (HMD, PC, control). For SCL, the results showed a significantly larger decrease in the HMD and PC than in the control condition, but no significant differences between the HMD and PC condition. For HR, there were no significant differences between the recovery conditions. However, the HMD condition was rated significantly more relaxing than the other conditions, with no significant differences between the PC and control condition. Exploratory analyses showed that these results were not moderated by the participants’ age, gender, or technology anxiety. Overall, the psychophysiological results showed no significant benefit favoring the HMD over PC condition, although the self-reported relaxation ratings did. Future studies are warranted to clarify this divergence.

Carbon and Neon Ion Bombardment Induced Smoothing and Surface Relaxation of Titania Nanotubes

Titania nanotube arrays with their enormous surface area are the subject of much attention in diverse fields of research. In the present work, we show that not only 60 keV and 150 keV ion bombardment of amorphous titania nanotube arrays yields defect creation within the tube walls, but it also changes the surface morphology: the surface relaxes and smoothens in accordance with a curvature-driven surface material’s transport mechanism, which is mediated by radiation-induced viscous flow or radiation-enhanced surface diffusion, while the nanotubes act as additional sinks for the particle surface currents. These effects occur independently of the ion species: both carbon and neon ion bombardments result in comparable surface relaxation responses initiated by an ion energy of 60 keV at a fluence of 1 × 1016 ions/cm2. Using atomic force microscopy and contact angle measurements, we thoroughly study the relaxation effects on the surface topography and surface free energy, respectively. Moreover, surface relaxation is accompanied by further amorphization in surface-near regions and a reduction in the mass density, as demonstrated by Raman spectroscopy and X-ray reflectivity. Since ion bombardment can be performed on global and local scales, it constitutes a versatile tool to achieve well-defined and tunable topographies and distinct surface characteristics. Hence, different types of nanotube arrays can be modified for various applications.

Relaxation Effects of Aromatherapy Intervention on Female and Male Anxiety: A Randomized Control Trial

Background: The control or reduction of anxiety before surgery is one of the most important components of preoperative care. The question is whether anxiety differs in male and female candidates for surgery. Objectives: The current study aimed to evaluate the effect of aromatherapy with Citrus aurantium on anxiety in men and women candidates for surgery. Methods: This single-blind randomized clinical trial was performed on 60 patients and controlled by placebo. The patients were divided into 30 subjects in the control group and 30 subjects in the aromatherapy group (inhaling C. aurantium essential oil). The patients completed the Spielberger state-trait anxiety inventory before and after the intervention. After collecting information, the questionnaire information was analyzed using SPSS software (version 16). Results: After aromatherapy, 20% of men had mild state and trait anxiety. Moreover, 80% of men had relatively mild state and trait anxiety. In the group of women, 20% of the cases had mild state and trait anxiety. Furthermore, 73.3% of women had relatively mild state and trait anxiety. Additionally, 6.7% of women had relatively severe anxiety. Anxiety reduced after the intervention among men and women (P < 0.001). In addition, the severity of anxiety among women in the control group increased after placebo intervention (P < 0.05). Moreover, the effect of C. aurantium aroma was further observed in women than men; however, there was no statistically significant difference (P > 0.05). Conclusions: The results of this study indicated that inhaling the C. aurantium aroma reduces anxiety in patients. Aromatherapy also has the potential to be replaced by chemical drugs due to fewer side effects and risks, and cost-effectiveness.