Increase In Hydrostatic Pressure Research Articles

Effects of temperature, pressure and thickness on a one-dimensional Thue-Morse photonic crystal

Using the transfer matrix method and the two-fluid model, we calculate the transmittance spectrum in a one-dimensional photonic crystal with the Thue-Morse fractal structure. The photonic crystal composed layers of semiconductor (GaAs) and superconductor (HgBa2Ca2Cu3O8+δ) materials. In this study, we researched the effects of the temperature, hydrostatic pressure and thickness increases of the superconducting layer on the transmittance spectrum. We report that the optical response is mainly due to the increase in pressure, with a shift towards the higher-frequency regions of the transmittance spectrum. Additionally, we found that transmittance peaks split by increasing the length of the fractal structure and new gaps appeared when the thickness of the superconducting layer increased.

The Ciliary Muscle and Zonules of Zinn Modulate Lens Intracellular Hydrostatic Pressure Through Transient Receptor Potential Vanilloid Channels.

PurposeLenses have an intracellular hydrostatic pressure gradient to drive fluid from central fiber cells to surface epithelial cells. Pressure is regulated by a feedback control system that relies on transient receptor potential vanilloid (TRPV)1 and TRPV4 channels. The ciliary muscle transmits tension to the lens through the zonules of Zinn. Here, we have examined if ciliary muscle tension influenced the lens intracellular hydrostatic pressure gradient.MethodsWe measured the ciliary body position and intracellular hydrostatic pressures in mouse lenses while pharmacologically causing relaxation or contraction of the ciliary muscle. We also used inhibitors of TRPV1 and TRPV4, in addition to phosphoinositide 3-kinase (PI3K) p110α knockout mice and immunostaining of phosphorylated protein kinase B (Akt), to determine how changes in ciliary muscle tension resulted in altered hydrostatic pressure.ResultsCiliary muscle relaxation increased the distance between the ciliary body and the lens and caused a decrease in intracellular hydrostatic pressure that was dependent on intact zonules and could be blocked by inhibition of TRPV4. Ciliary contraction moved the ciliary body toward the lens and caused an increase in intracellular hydrostatic pressure and Akt phosphorylation that required intact zonules and was blocked by either inhibition of TRPV1 or genetic deletion of the p110α catalytic subunit of PI3K.ConclusionsThese results show that the hydrostatic pressure gradient within the lens was influenced by the tension exerted on the lens by the ciliary muscle through the zonules of Zinn. Modulation of the gradient of intracellular hydrostatic pressure in the lens could alter the water content, and the gradient of refractive index.

Weak antilocalization effect and high-pressure transport properties of ScPdBi single crystal

Half-Heusler compounds have attracted considerable attention due to their fantastic physical properties that include topological effects, Weyl fermions, unusual magnetism, and superconductivity. Herein, the transport properties of half-Heusler ScPdBi single crystals are studied across a wide temperature range and different magnetic fields. From the field-dependent magnetoresistance, we observe a clear weak antilocalization (WAL) effect below 200 K in the low magnetic-field region. The angle-dependent magnetoconductance and the ultralarge prefactor α extracted from the Hikami-Larkin-Nagaoka equation reveal that the WAL effect is a 3D bulk effect caused by strong spin–orbit coupling. We further studied the magnetotransport properties of the single crystal upon application of hydrostatic pressure and found that the energy gap of ScPdBi increases gradually as the hydrostatic pressure increases. Density functional theory calculations confirm that applying hydrostatic pressure decreases the lattice parameters and, consequently, enlarges the bandgap.

The haemodynamic basis of lung congestion during exercise in heart failure with preserved ejection fraction

Increases in extravascular lung water (EVLW) during exercise contribute to symptoms, morbidity, and mortality in patients with heart failure and preserved ejection fraction (HFpEF), but the mechanisms leading to pulmonary congestion during exercise are not well-understood. Compensated, ambulatory patients with HFpEF (n = 61) underwent invasive haemodynamic exercise testing using high-fidelity micromanometers with simultaneous lung ultrasound, echocardiography, and expired gas analysis at rest and during submaximal exercise. The presence or absence of EVLW was determined by lung ultrasound to evaluate for sonographic B-line artefacts. An increase in EVLW during exercise was observed in 33 patients (HFpEFLW+, 54%), while 28 (46%) did not develop EVLW (HFpEFLW-). Resting left ventricular function was similar in the groups, but right ventricular (RV) dysfunction was two-fold more common in HFpEFLW+ (64 vs. 31%), with lower RV systolic velocity and RV fractional area change. As compared to HFpEFLW-, the HFpEFLW+ group displayed higher pulmonary capillary wedge pressure (PCWP), higher pulmonary artery (PA) pressures, worse RV-PA coupling, and higher right atrial (RA) pressures during exercise, with increased haemoconcentration indicating greater loss of water from the vascular space. The development of lung congestion during exercise was significantly associated with elevations in PCWP and RA pressure as well as impairments in RV-PA coupling (area under the curve values 0.76-0.84). Over half of stable outpatients with HFpEF develop increases in interstitial lung water, even during submaximal exercise. The acute development of lung congestion is correlated with increases in pulmonary capillary hydrostatic pressure that favours fluid filtration, and systemic venous hypertension due to altered RV-PA coupling, which may interfere with fluid clearance. NCT02885636.

CdS/HgS Cylindrical Core/Shell: The simultaneous effect of the hydrostatic pressure and temperature on the diamagnetic susceptibility of hydrogenic donor impurity

One of the most important factors of controlling the properties of the above mentioned systems is hydrostatic pressure and temperature. The effect of the hydrostatic pressure and temperature on diamagnetic susceptibility and binding energy of a center hydrogenic donor impurity has been theoretically investigated in the framework of the effective mass approximation. We describe the quantum confinement by an infinite deep potential. The results for a cylindrical Inhomogeneous quantum dots made out of [CdS (Core) / HgS (Well) / CdS (Shell)] show that (i) when the hydrostatic pressure increase, the diamagnetic susceptibility decreases and the binding energy increases. (ii) The diamagnetic susceptibility increases with the temperature.

Between plate and salt tectonics—New stratigraphic constraints on the architecture and timing of the Dead Sea basin during the Late Quaternary

AbstractThe Dead Sea is an extensional basin developing along a transform fault plate boundary. It is also a terminal salt basin. Without knowledge of precise stratigraphy, it is difficult to differentiate between the role of plate and salt tectonics on sedimentary accumulation and deformation patterns. While the environmental conditions responsible for sediment supply are reasonably constrained by previous studies on the lake margins, the current study focuses on deciphering the detailed stratigraphy across the entire northern Dead Sea basin as well as syn and post‐depositional processes. The sedimentary architecture of the late Quaternary lacustrine succession was examined by integrating 851 km of seismic reflection data from three surveys with gamma ray and velocity logs and the stratigraphic division from an ICDP borehole cored in 2010. This allowed seismic interpretation to be anchored in time across the entire basin. Key surfaces were mapped based on borehole lithology and a newly constructed synthetic seismogram. Average interval velocities were used to calculate isopach maps and spatial and temporal sedimentation rates. Results show that the Amora Formation was deposited in a pre‐existing graben bounded by two N‐S trending longitudinal faults. Both faults remained active during deposition of the late Pleistocene Samra and Lisan Formations—the eastern fault continued to bound the basin while the western fault remained blind. On‐going plate motion introduced a third longitudinal fault, increasing accommodation space westwards from the onset of deposition of the Samra Formation. During accumulation of these two formations, sedimentation rates were uniform over the lake and similar. High lake levels caused an increase in hydrostatic pressure. This led to salt withdrawal, which flowed to the south and southwest causing increased uplift of the Lisan and En Gedi diapirs and the formation of localized salt rim synclines. This induced local seismicity and slumping, resulting in an increased thickness of the Lisan succession within the lake relative to its margins. Sedimentation rates of the Holocene Ze'elim Fm were 4–5 times higher than before. The analysis presented here resolves central questions of spatial extent and timing of lithology, deposition rates and their variability across the basin, timing of faulting at and below the lake floor, and timing and extent of salt and plate tectonic phases and their effect on syn and post‐depositional processes. Plate tectonics dictated the structure of the basin, while salt tectonics and sediment accumulation were primarily responsible for its fill architecture during the timeframe examined here.

Strong Dependence of Contact Angle on Pressure

Although the usual pressures typically only slightly affect the properties of condensed phases and their surface layers, in physical chemistry of surfaces, it was found a quantity, the contact angle on the three-phase contact line, that is very sensitive to pressure. In experiments with an air bubble in water stuck to a solid surface, an increase in hydrostatic pressure of less than doubled gave an increase in the contact angle of more than 10o if the angle itself was sufficient but less than 90o. Сhanging the orientation of the liquid - gas surface. If the angle (no matter sharp or obtuse) is close to 90o, the mobility of the three-phase contact line arises as an alternative way to achieve equilibrium. To explain these phenomena, a thermodynamic theory is formulated. It is shown that with a fixed line of three-phase contact, an increase in pressure in a liquid always causes an increase in the contact angle. At the same time, an increase in the hydrostatic pressure of water by two times is equivalent to an increase in the partial pressure of water vapor inside the bubble by a factor of seven.

Physical properties of Ti3SiC2/Zr heterojunction under hydrostatic pressure

The geometric structure, elastic constants and electronic properties of Ti3SiC2/Zr heterojunctions under high hydrostatic pressure (0-10GPa) were investigated by first-principles calculations. It’s found that the increase of hydrostatic pressure loaded on the Ti3SiC2/Zr heterojunctions induces the monotonically decrease of their lattice parameters. Under hydrostatic pressure below 10GPa, the Ti3SiC2/Zr heterojunction is stable and its elastic properties change linearly with pressure. Ti3SiC2/Zr heterojunction under hydrostatic pressure is found to be ductile material, and its anisotropy is weak. Finally, Ti3SiC2/Zr heterojunction under hydrostatic pressure retains metallic properties, and hydrostatic pressure slightly changes the band structure of Ti3SiC2/Zr heterojunction.

Pressure effect on the diamagnetic susceptibility of donor in HgS and GaAs cylindrical quantum dot

The binding energy and diamagnetic susceptibility of shallow hydrogenic impurity in cylindrical quantum dot is calculated using a variational approach within the effective mass approximation, as a function of dot size when the static pressure and the magnetic field are applied simultaneously. We describe the quantum confinement by an infinite deep potential; the numerical calculations are performed for HgS, which is a narrow gap, and GaAs, a large gap semiconductor. The results show that the diamagnetic susceptibility increases with the reduction in dot sizes and decreases when the hydrostatic pressure increases. We have shown that diamagnetic susceptibility strongly depends on size of the nanostructure and decreases with increasing size of the quantum dot and tends toward the limit of the bulk (−1, 1 a.u.) (increase in diamagnetic susceptibility in absolute value). We have found that the displacement of the impurity from the center of the quantum dot to the edge causes a decrease in the diamagnetic susceptibility. The absolute value of diamagnetic susceptibility of donors in GaAs is lower than in HgS.

Superconductivity in YIn3 under positive pressure

Positive hydrostatic pressure was applied on YIn3 and variation in superconducting transition temperature (Tc) and average coupling constant (λep) was observed. The variation in phonon dispersion relation, Eliashberg spectral function, phonon DOS and average logarithmic phonon frequency was studied with an increase in positive hydrostatic pressure. The dispersion relation for YIn3 under ambient and all applied positive pressure shows positive frequency for all modes of vibrations signifying the structural stability of YIn3 under all applied pressures.

Insight into the formation, structure and digestibility of lotus seed amylose-fatty acid complexes prepared by high hydrostatic pressure

Lotus seed amylose-fatty acid complexes were prepared using high hydrostatic pressure and the relationship between their structural properties and digestibility was investigated. The formation of lotus seed amylose-fatty acid complexes increased the values of weight molar mass (Mw), number molar mass (Mn), polydispersity index and resistant starch content compared to those of amylose controls. Mw and Mn values of lotus seed amylose and complexes decreased with an increase in high hydrostatic pressure from 500 MPa to 600 MPa, suggesting that the lotus seed amylose was decomposed into short glucan chains. The presence of single helical lotus seed amylose-fatty acid complexes and double helical retrograded amylose was investigated using Raman spectroscopy and imaging. The results from Raman spectra and in vitro digestion showed that the content of both single helical LSA-fatty acid complexes and double helical retrograded LSA were responsible for digestibility of the complex matrix.

Influence of Pressure on Polaron Energy in a Wurtzite GaN/Al<sub>x</sub>Ga<sub>1-x</sub>N Quantum Well

The influence of hydrostatic pressure on the polaron energy level in wurtzite GaN/AlxGa1-xN quantum well is studied by a Lee-Low-Pines variational method, and the numerical results of the ground state energy, transition energy and contributions of different phonons to polaron energy (polaron effects) are given as functions of pressure p and composition x. The results show that the ground state energy and transition energy in the wurtzite GaN/AlxGa1-xN quantum well decrease with the increase of the hydrostatic pressure p, and increase with the increase of the composition x. The contributions of different phonons to polaron energy with pressure p and composition x are obviously different. With the increase of hydrostatic pressure, the contribution of half-space phonon, confined phonon and the total contribution of phonons of all branches increases obviously, while the contribution of interface phonon slowly increases. During the increase of the composition, the contribution of interface phonon decreases and the contribution of half-space phonon increases slowly, while the contribution of confined phonon and the total contribution of phonons increases significantly. In general, the electron-optical phonon interaction play an important role in electronic states of GaN/AlxGa1-xN quantum wells and can not be neglected.

On-Chip Cell Incubator for Simultaneous Observation of Culture with and without Periodic Hydrostatic Pressure.

This paper proposes a microfluidic device which can perform simultaneous observation on cell growth with and without applying periodic hydrostatic pressure (Yokoyama et al. Sci. Rep. 2017, 7, 427). The device is called on-chip cell incubator. It is known that culture with periodic hydrostatic pressure benefits the elasticity of a cultured cell sheet based on the results in previous studies, but how the cells respond to such a stimulus during the culture is not yet clear. In this work, we focused on cell behavior under periodic hydrostatic pressure from the moment of cell seeding. The key advantage of the proposed device is that we can compare the results with and without periodic hydrostatic pressure while all other conditions were kept the same. According to the results, we found that cell sizes under periodic hydrostatic pressure increase faster than those under atmospheric pressure, and furthermore, a frequency-dependent fluctuation of cell size was found using Fourier analysis.

A new approach to measure the resistance of fabric to liquid and viral penetration.

Protective clothing manufacturers routinely test their products for resistance to liquid and viral penetration. Several of the test methods specified by the American Society for Testing and Materials (ASTM) and the International Organization for Standardization (ISO) for penetration testing produce binary results (i.e. pass or fail), deliver imprecise pressure regulation, and do not record the location at which penetration events occur. Instead, our approach measures a continuous variable (time of penetration) during a slow and continuous increase of hydrostatic pressure and retains the location of penetration events. Using a fluorescent dye to enhance visual detection, we evaluate temporal and spatial patterns of penetration events. We then compare the time of liquid penetration with the time of penetration of two bacteriophages (Phi-X174 and MS2). For the fabric tested, the mean viral penetration occurred 0.29 minutes earlier than liquid penetration when solved by logistic regression. The breakthrough time of MS2 was not different from the Phi-X174 bacteriophage. The time of liquid penetration was a latent indicator of the time of viral penetration.

Pressure-dependent photoluminescence of CdSe/ZnS quantum dots: Critical point of different pressure regimes

High pressure condition can alter and control the electronic structure of semiconductor quantum dots, and therefore provides novel insight for designing optoelectronic devices. Here we report the pressure-dependent photoluminescence (PL) of CdSe/ZnS core/shell quantum dots (QD) in different pressure regimes. The center of the PL spectrum has blue-shift when hydrostatic pressure increases, due to the increasing bulk modulus. However, the shifting rate becomes lower in the higher pressure regime, i.e. above the critical pressure point, mainly due to the interaction between QDs. Accordingly, the lifetimes of PL drop in the low pressure regime, due to the increased pressure-induced trapping states, then increase above the critical pressure point, indicating the interaction between dots likewise. The observed critical pressures for both cases are consistent with each other, and strongly depend on the QD concentration, which forcefully support the aforementioned interaction model.

Effect of Parameters of Liquids on Amplitudes of Pressure Waves Generated by Electric Discharge

An experimental study is performed on the effect of hydrostatic pressure, temperature and specific electric conductivity of a liquid on the amplitude of a pressure wave generated by an electric discharge in a liquid during the electric discharge treatment of oil wells. The results show that with an increase in hydrostatic pressure the amplitude of the generated pressure wave decreases. The use of a fluid with a conductivity of 0.53 S/m as a working medium (which is close to the value of a specific conductivity of the produced water) decreases (up to 67%) the amplitude of the pressure wave. During the treatment of the oil wells using the electric discharge immersion device, it is necessary to use a scheme with a closed electrode system, since in this case the treatment efficiency is independent of the electric conductivity of the downhole fluid.

Influences on the Functional Behavior of Great Arteries during Orthostasis.

BackgroundArterial compliance reduction has been associated with aging and hypertension in supine position. However, the dynamic effects of orthostatism on aortic distensibility has not been defined.ObjectiveWe sought to determine the orthostatic influence and the interference of age, blood pressure (BP) and heart rate (HR) on the great arteries during gravitational stress.MethodsNinety-three healthy volunteers (age 42 ± 16 years). Carotid-femoral pulse wave velocity (PWV) assumed as aortic stiffness was assessed in supine position (basal phase), during tilt test (TT) (orthostatic phase) and after return to supine position (recovery phase). Simultaneously with PWV acquisition, measures of BP and HR rate were recorded.ResultsPWV during TT increased significantly compared to the basal and recovery phases (11.7 ± 2.5 m/s vs. 10.1 ± 2.3 m/s and 9.5 ± 2.0 m/s). Systolic BP (r = 0.55, r = 0.46 and r = 0.39) and age (r = 0.59, r = 0.63 and r = 0.39) correlated with PWV in all phases. The significance level for all tests was established as α = 0.05.ConclusionWe conclude that there is a permanent increase in PWV during orthostatic position that was returned to basal level at the recovery phase. This dynamic pattern of PWV response, during postural changes, can be explained by an increase in hydrostatic pressure at the level of abdominal aorta which with smaller radius and an increased elastic modulus, propagates the pulse in a faster way. Considering that it could increase central pulse reflection during the orthostatic position, we speculate that this mechanism may play a role in the overall adaptation of humans to gravitational stress.

Photonic band structure in a 2D honeycomb lattice of triangular holes

In this study, we calculate the photonic band structure for a honeycomb two-dimensional photonic crystal lattice composed triangular holes embedded in GaAs. We assume that the GaAs dielectric function depends on the applied hydrostatic pressure and temperature. The plane wave expansion method is used to calculate the PBS for transverse electric (TE) and transverse magnetic (TM) polarizations. At constant temperature, we find that if the hydrostatic pressure increases, the PBS for both polarizations shifts to higher energies without modifying the gap width. On removing a triangular hole from the structure, both gap position and width remain unchanged for TM polarizations with the presence of a defective band whose energy is tuned to pressure increases.

Failure and strain gradient analyses in incremental forming using GTN model

Single point incremental forming (SPIF) process is gaining popularity for rapid manufacturing of complex 3D shapes. The present study is aimed at numerically predicting the failure using the Gurson-Tvergaard-Needleman (GTN) model and further clarifying the deformation mechanics in SPIF. Deformation mechanics and failure in SPIF process are examined numerically by simulating a straight groove test. Solid finite element (FE) models have been employed to investigate deformation modes. The GTN damage model has successfully predicted forming limits in the straight groove test. It is shown that failure, regardless of the incremental sheet forming (ISF) conditions, occurs when the damage parameter (d) approaches one. Furthermore, effective plastic strain, hydrostatic pressure, vertical tool force and through thickness strain gradient increase with an increase in step size. Finally, it is shown that an increase in hydrostatic pressure and increase in through thickness strain gradient enhance formability.

Effect of Deep Sea Pressures on the Corrosion Behavior of X65 Steel in the Artificial Seawater

The corrosion behaviors of X65 steel in the artificial seawater at different hydrostatic pressures are investigated by potentiodynamic polarization measurements, electrochemical impedance spectroscopy measurements and weight loss measurements. The corroded morphologies and the corrosion products are also investigated by scanning electron microscopy, X-ray diffraction analysis and Raman analysis. The results show that the corrosion current increases as the hydrostatic pressure increases. The charge transfer resistance decreases as the hydrostatic pressure increases. The corrosion products are mainly composed of γ-FeOOH and Fe3O4 at the atmospheric pressure, while the main components are γ-FeOOH, Fe3O4, and γ-Fe2O3 at the high pressure. The hydrostatic pressure accelerates the corrosion of X65 steel due to its effect on the chemical and physical properties of corrosion products, including the promoted reduction of γ-FeOOH and the wider and deeper cracks on the corrosion products layer.