RESUMEN

HYPOTHESIS: Recently, it has been reported that anomalous improvement in the thermal conductivity of nanofluid composed of base liquids and dispersed solid nanoparticles, compared to the theoretically predicted value calculated from the particle fraction. Generally, the thermal conductivity values of gases and liquids are dominated by the mean free path of the molecules during translational motion. Herein, we present solid evidence showing the possible contribution of the vibrational behavior of liquid molecules around nanoparticles to increasing these thermal conductivities. EXPERIMENTS: The behavior of liquid molecules in nanofluids containing SiO2 particles larger than 100 nm, which were dispersed in a 50 wt% aqueous solution of ethylene glycol, was investigated by means of small-angle neutron scattering, quasi-elastic neutron scattering, wide-angle X-ray scattering, and Raman spectroscopy. FINDINGS: The vibrational changes in the liquid molecules caused by the interactions between the nanoparticles and liquid molecules surrounding the nanoparticles contributed majorly to the increase in the thermal conductivity values of the SiO2 nanofluids. Because the vibration of liquid molecules is equivalent to phonon conduction in solids, the increase in thermal conductivity of the suspension due to the presence of nanoparticles was inferred to be derived from the limitation of the translational diffusion, which induces a solid-like behavior in the liquid.

RESUMEN

A varifocal concave-convex lens using ultrasound and transparent viscoelastic gel is reported. The configuration of the lens is simple and thin, consisting of four pieces of a piezoelectric ultrasound transducer, a glass disk, and a transparent silicone gel film. It uses a combination of the ultrasound resonant flexural standing- and traveling-wave modes excited by in-phase and four-phase drives so that the lens can change its shape to both concave and convex by switching the resonance mode with the same structure. The acoustic radiation force (ARF) originated from the resonant flexural vibration modes changed the surface profile of the gel. Convex and concave deformation were generated at the center of the lens at the resonance frequencies of 38 and 60 kHz, respectively, indicating that a varifocal concave-convex lens could be fabricated by controlling the driving frequency, voltage amplitude, and phase differences among the ultrasound transducers. The deformational displacement on the lens surface and the change in the focal length increased with the input voltage amplitude. The optical microscopic images observed through the lens were enlarged 1.28× (reduced 0.92× ) in the convex (concave) mode with 20 [Formula: see text]. The response time for focusing and the temperature stability under operation were evaluated. By switching the resonance vibration modes of the lens through the input signals to multiple ultrasound transducers, the variable-focus function with both concave and convex lenses was achieved in the same configuration.

Asunto(s)

RESUMEN

Strenuous exercise induces organ damage, inflammation, and oxidative stress. Currently, to monitor or investigate physiological conditions, blood biomarkers are frequently used. However, blood sampling is perceived to be an invasive method and may induce stress. Therefore, it is necessary to establish a non-invasive assessment method that reflects physiological conditions. In the present study, we aimed to search for useful biomarkers of organ damage, inflammation, oxidative stress, and bone turnover in urine following exercise. Ten male runners participated in this study and performed a 3000-m time trial. We measured biomarkers in urine collected before and immediately after exercise. Renal damage markers such as urea protein, albumin, N-acetyl-ß-D-glucosaminidase (NAG), and liver-fatty acid binding protein (L-FABP), and an intestinal damage marker, intestine-fatty acid binding protein (I-FABP), increased following exercise (p < 0.05). However, a muscle damage marker, titin N-terminal fragments, did not change (p > 0.05). Inflammation-related factors (IRFs), such as interleukin (IL)-1ß, IL-1 receptor antagonist (IL-1ra), IL-6, complement (C) 5a, myeloperoxidase (MPO), calprotectin, monocyte chemoattractant protein (MCP)-1, and macrophage colony-stimulating factor (M-CSF), increased whereas IRFs such as IL-4 and IL-10 decreased following exercise (p < 0.05). IRFs such as tumor necrosis factor (TNF)-α, IL-2, IL-8, IL-12p40, and interferon (IFN)-γ did not change (p > 0.05). Oxidative stress markers, such as thiobarbituric acid reactive substances (TBARS) and nitrotyrosine, did not change following exercise (p > 0.05) whereas 8-hydroxy-2'-deoxyguanosine (8-OHdG) decreased (p < 0.05). Bone resorption markers, such as cross-linked N-telopeptide of type I collagen (NTX) and deoxypyridinoline (DPD), did not change following exercise (p > 0.05). These results suggest that organ damage markers and IRFs in urine have the potential to act as non-invasive indicators to evaluate the effects of exercise on organ functions.

RESUMEN

Prolonged strenuous exercise may induce inflammation, cause changes in gastrointestinal permeability, and lead to other unfavorable biological changes and diseases. Nutritional approaches have been used to prevent exercise-induced inflammatory responses and gastrointestinal disorders. Hyperimmunized milk, obtained by immunizing cows against specific antigens, promotes the development of immunity against pathogens, promotes anti-inflammatory effects, and protects intestinal function. Immune protein (IMP) is a concentrated product of hyperimmunized milk and is a more promising means of supplementation to protect against acute infections and inflammation. To determine whether IMP has protective properties against exercise-induced gastrointestinal dysfunction and inflammation, we examined biochemical markers, intestinal damage markers, and pro-/anti-inflammatory profiles of young male runners using a randomized, placebo controlled, cross-over design. Urine samples were collected and used for measurements of creatinine, N-acetyl-ß-d-glucosaminidase, osmotic pressure, and specific gravity. Titin was measured as a muscle damage marker. Further, urine concentrations of complement 5a, calprotectin, fractalkine, myeloperoxidase, macrophage colony-stimulating factor, monocyte chemotactic protein-1, intestinal fatty acid binding protein (I-FABP), interferon (IFN)-γ, interleukin (IL)-1ß, IL-1 receptor antagonist, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p40, and tumor necrosis factor (TNF)-α were measured by enzyme-linked immunosorbent assays. We demonstrated that urine osmotic pressure, urine specific gravity, I-FABP, IFN-γ, IL-1ß, and TNF-α were reduced by 8 weeks of IMP supplementation, indicating that IMP may have potential in preventing strenuous exercise-induced renal dysfunction, increased intestinal permeability, and inflammation. Thus, IMP supplementation may be a feasible nutritional approach for the prevention of unfavorable exercise-induced symptoms.

RESUMEN

Thermodynamic stability boundary of structure-H hydrates with large guest species and methane (CH4) at extremely high pressures has been almost unclear. In the present study, the four-phase equilibrium relations in the structure-H CH4 + 1,1,2,2,3,3,4-heptafluorocyclopentane (1,1,2,2,3,3,4-HFCP) mixed hydrate system were investigated in a temperature range of (281.05 to 330.12) K and a pressure range up to 373 MPa. The difference between equilibrium pressures in the structure-H CH4 + 1,1,2,2,3,3,4-HFCP mixed hydrate system and the structure-I simple CH4 hydrate system gets larger with increase in temperature. The structure-H CH4 + 1,1,2,2,3,3,4-HFCP mixed hydrate survives even at 330 K and 373 MPa without any structural phase transition. The maximum temperature where the structure-H CH4 + 1,1,2,2,3,3,4-HFCP mixed hydrate is thermodynamically stable is likely to be beyond that of the structure-H simple CH4 hydrate.

Asunto(s)