Pressure Medium Research Articles

Can quasicrystals survive in planetary collisions?

We investigated the compressional behavior of i-AlCuFe quasicrystal using diamond anvil cell under quasi-hydrostatic conditions by in situ angle-dispersive X-ray powder diffraction measurements (in both compression and decompression) up to 76 GPa at ambient temperature using neon as pressure medium. These data were compared with those collected up to 104 GPa using KCl as pressure medium available in literature. In general, both sets of data indicate that individual d-spacing shows a continuous decrease with pressure with no drastic changes associated to structural phase transformations or amorphization. The d/d0, where d0 is the d-spacing at ambient pressure, showed a general isotropic compression behavior. The zero-pressure bulk modulus and its pressure derivative were calculated fitting the volume data to both the Murnaghan- and Birch-Murnaghan equation of state models. Results from this study extend our knowledge on the stability of icosahedrite at very high pressure and reinforce the evidence that natural quasicrystals formed during a shock event in asteroidal collisions and survived for eons in the history of the Solar System.

About the Origin of the Dark Energy and the Zero Mass/Energy Universe

Based on the Gravito-Electro-Magnetic (GEM) equations as another form (for low fields) of Einstein's Equations of General Relativity Theory (GRT) an equation is derived for the total energy density in the universe, including the gravitational fields, the contribution thereof is always negative and so it seems to represents the Dark Energy (DE). When calculating the total energy of the universe from this equation, the result is near to zero because of negative contributions from gravitational fields, depending a little on the available parameters of the universe as e.g. it's baryonic mass. Thus the assumption is given a high amount of probability, that the total energy (mass) in the universe is really zero and very likely is always zero. This would mean, that the universe developed from empty space-time or from nothing (may be by quantum fluctuations). Looking on the development it could be that the average energy density is zero for each sufficient large part of the universe at any time, except for very local deviations (e.g. galaxies, black holes etc.). As a consequence the expansion of the universe is probably not retarded by gravity (thus the Friedmann equation and others do not apply). The expansion of the universe can be considered as driven by the pressure of a gas-like medium with positive masses as by intergalactic gas, dust, stars and galaxies. Conclusions are drawn as to the interpretation of the formation of voids in the universe, flat space etc.

The electrical conductivity of albite feldspar: Implications for oceanic lower crustal sequences and subduction zones

Abstract Volatile-sensitive electrical soundings are becoming more widely adopted, with large nationwide arrays currently being acquired globally. This boom in new data is despite several key uncertainties relating to the electrical responses of a wide range of minerals that make up crustal regions. Complications include the influence of mineral chemistry, hydrous or nominally hydrous phases, and oxygen fugacity on charge-carrying ion activity within a mineral substrate. Feldspars are the most abundant mineral group in the Earth’s crust, comprising about 60% of its mineral assemblages and are particularly prevalent within subduction zones and lower crustal sequences. These areas are known locations where ore systems are commonly rooted, making them among the most widely studied regions in the Earth. To date, few studies exist that cover the electrical behavior of the feldspar mineral albite. To help address some of these issues and complications, we have undertaken electrical conductivity investigations on a single crystal of gem-quality albite (Ab49An48Or3) from Nuevo Casas Grande, Chihuahua, Mexico. Electrical conductivity measurements using impedance spectroscopy were performed at a pressure of 1 GPa over a temperature range of 373–1273 K in a multi-anvil high-pressure apparatus. Experiments were carried out using different metal electrodes: molybdenum, nickel, and rhenium to vary the oxygen fugacity during the experiments. FTIR measurements of the starting and final materials confirm that the initial samples are completely dry but absorb an average of 67 ppm H2O by mass during the experiments from the surrounding pressure medium materials. We observe no correlation in the amount of water absorbed in the feldspar to the oxygen fugacity under water-undersaturated conditions. Our investigations show that the activation enthalpy increases from ~0.77 to ~1.0 eV from the nominally hydrous to the completely dry feldspar. The activation enthalpy decreases with increasing oxygen fugacity for comparable water contents. An oxygen fugacity exponent of –0.069 is calculated at the nominal water content measured in the experiments, indicating an electrical conductivity mechanism that also involves the mobility of hydrogen.

Direct Observation of Conversion From Walled Cells to Wall-Deficient L-Form and Vice Versa in Escherichia coli Indicates the Essentiality of the Outer Membrane for Proliferation of L-Form Cells.

Gram-negative bacteria such as Escherichia coli are surrounded by an outer membrane, which encloses a peptidoglycan layer. Even if thinner than in many Gram-positive bacteria, the peptidoglycan in E. coli allows cells to withstand turgor pressure in hypotonic medium. In hypertonic medium, E. coli treated with a cell wall synthesis inhibitor such as penicillin G form wall-deficient cells. These so-called L-form cells grow well under anaerobic conditions (i.e., in the absence of oxidative stress), becoming deformed and dividing as L-form. Upon removal of the inhibitor, they return to the walled rod-shaped state. Recently, the outer membrane was reported to provide rigidity to Gram-negative bacteria and to strengthen wall-deficient cells. However, it remains unclear why L-form cells need the outer membrane for growth. Using a microfluidic system, we found that, upon treatment with the outer membrane-disrupting drugs polymyxin B and polymyxin B nonapeptide or with the outer membrane synthesis inhibitor CHIR-090, the cells lysed during cell deformation and division, indicating that the outer membrane was important even in hypertonic medium. L-form cells could return to rod-shaped when trapped in a narrow space, but not in a wide space, likely due to insufficient physical force. Outer membrane rigidity could be compromised by lack of outer membrane proteins; Lpp, OmpA, or Pal. Deletion of lpp caused cells to lyse during cell deformation and cell division. In contrast, ompA and pal mutants could be deformed and return to small oval cells even when less physical force was exerted. These results strongly suggest that wall-deficient E. coli cells require a rigid outer membrane to survive, but not too rigid to prevent them from changing cell shape.

Layered Double Hydroxides-Based Mixed Metal Oxides: Development of Novel Structured Sorbents for CO2 Capture Applications.

Layered double hydroxide (LDHs)-based mixed metal oxides (MMOs) are widely studied as the medium to high temperature (200-400 °C) CO2 capture sorbents. However, most of the studies are carried out using the powdered samples. To upgrade these sorbents for industrial-scale CO2 capture, it is important to move away from the powdered form and develop structured sorbents. Moreover, the CO2 capture properties of these sorbents need to be improved in terms of capture capacity and cycling stability. Here we are utilizing a modified amide hydrolysis method to improve the CO2 capture capacities of LDHs-based MMOs. Subsequently, aqueous exfoliation coupled with the freeze-drying technique was utilized to develop LDHs-based novel MMOs. Exfoliated LDH nano sheets were pelletized (2 mm) to circumvent the challenges associated with powder samples when used in industrial-scale applications. The obtained pellets have an average crushing load of 11.1 N and 4.3 MPa of compressive strength, which indicate their good mechanical stability. The MMOs pellets showed a narrow distribution of pores (8-10 nm) with very good surface area (264 m2/g) and pore volume (1.27 cm3/g). They also had much improved CO2 capture capacities at ambient pressure and both low (2.17 mmol/g, 30 °C) and medium temperature (1.43 mmol/g, 200 °C), as compared to previously reported pristine MMOs powder samples. The pelletized structured sorbents also outperformed commercial LDH-based pellets by several fold.

Jet Collimation and Acceleration in the Giant Radio Galaxy NGC 315

Abstract We study the collimation and acceleration of jets in the nearby giant radio galaxy NGC 315, using multifrequency Very Long Baseline Array observations and archival High Sensitivity Array and Very Large Array data. We find that the jet geometry transitions from a semi-parabolic shape into a conical/hyperbolic shape at a distance of ≈105 gravitational radii. We constrain the frequency-dependent position of the core, from which we locate the jet base. The jet collimation profile in the parabolic region is in good agreement with the steady axisymmetric force-free electrodynamic solution for the outermost poloidal magnetic field line anchored to the black hole event horizon on the equatorial plane, similar to the nearby radio galaxies M87 and NGC 6251. The velocity field derived from the asymmetry in brightness between the jet and counterjet shows gradual acceleration up to the bulk Lorentz factor of Γ ∼ 3 in the region where the jet collimation occurs, confirming the presence of the jet acceleration and collimation zone. These results suggest that the jets are collimated by the pressure of the surrounding medium and accelerated by converting Poynting flux to kinetic energy flux. We discover limb brightening of the jet in a limited distance range where the angular resolution of our data is sufficient to resolve the jet transverse structure. This indicates that either the jet has a stratified velocity field of fast-inner and slow-outer layers or the particle acceleration process is more efficient in the outer layer owing to the interaction with the surroundings on parsec scales.

Influence of self-reflected radiation on plasma characteristics gas-discharge lamp

The paper deals with the influence on the parameters of the discharge in cesium – mercury – xenon vapor-gas mixture returned back to the plasma of the self-radiation of a gas-discharge lamp. The transformation of the radiation spectrum and the formation of a plasma channel upon reaching the quasi-stationary stage have been studied. As a result of studying the self-reversal of the resonance line of cesium, the decisive role of the increase in the vapor pres-sure of the plasma-forming medium on the change in the characteristics of the plasma has been proved.

Investigation of the Performance of the Interval Radial-Stop In-Line Device Under Conditions of Increased Pressure

The article reflects the results of a study to determine the operability of an interval radial-thrust in-line device, intended for use in the repair of the linear part of main gas pipelines. The paper contains information characterizing the stress-strain state of the most wear-out elements of the inline shell. The problem is reduced to finding the equivalent stresses for the initially selected material. The results of the study indicate that under the conditions of a one-sided force factor (pressure) of the gas pipeline medium, the limiting state of the material of the end element is not reached. As a methodological basis for the study, the use of finite element analysis is assumed. The result of the study is a picture of the distribution of equivalent stresses in the plane of the end element.

In vitro growth culture in a medium with reduced sodium chloride improves maturation and developmental competence of pig oocytes derived from small antral follicles

The objective of this study was to evaluate the effects of reducing the sodium chloride content in in vitro growth (IVG) medium to 61.6 mM on in vitro maturation (IVM) and embryonic development of pig oocytes derived from small antral follicles (SAF) less than 3 mm in diameter. SAF oocytes were cultured for 2 days to induce IVG in alpha-minimal essential medium with 108 mM NaCl (αMEM-108) or porcine zygote medium (PZM) containing 61.6 mM (PZM-61.6) or 108 mM (PZM-108) NaCl. These media were further supplemented with 1 mM dibutyryl cyclic adenosine monophosphate (dbcAMP) and 10% (v/v) fetal bovine serum. After IVG culture, oocytes were matured for 44 h in our standard IVM medium. The IVG culture in PZM-61.6 significantly increased nuclear maturation (88.0 ± 2.2%) of SAF oocytes compared to that in PZM-108 (77.3 ± 3.9%) or αMEM-108 (75.9 ± 3.8%). After parthenogenesis (PA), the proportions of blastocysts, based on the number of metaphase II (MII) oocytes, induced for PA were not different among IVG oocytes cultured in PZM-61.6 (50.2 ± 3.0%), PZM-108 (46.8 ± 2.9%), or αMEM-108 (45.6 ± 2.9%). The IVM oocytes derived from IVG in PZM-61.6 showed increased perivitelline space (PVS) (12.1 ± 0.6 μm) and intra-oocyte glutathione (GSH) content (1.19 ± 0.04 pixels/oocyte) compared to PVS (8.0 ± 0.5 and 7.4 ± 0.4 μm) and GSH (1.03 ± 0.04 and 1.00 ± 0.04 pixels/oocyte) of oocytes derived from PZM-108 and αMEM-108, respectively. The IVG culture in PZM-61.6 stimulated meiotic resumption after IVG and faster nuclear progression after IVM than that in αMEM-108. After somatic cell nuclear transfer (SCNT), the blastocyst formation of SAF oocytes grown in PZM-61.6 (17.8 ± 3.3%) was higher than that of oocytes grown in PZM-108 (7.5 ± 2.7%) but not different from that of oocytes in αMEM-108 (11.4 ± 3.4%). Regardless of the different osmotic pressures, nuclear maturation was significantly increased by IVG culture in PZM with reduced NaCl (86.8 ± 2.3 and 84.9 ± 4.2% in PZM-61.6 and PZM-61.6 with sorbitol, respectively) than in PZM-108 (70.5 ± 3.4%). Blastocyst formation was not affected by the differences in NaCl content and osmotic pressure of the IVG medium, whereas the mean number of cells in blastocysts was significantly higher following IVG culture in PZM-61.6 than in the other groups. In conclusion, the results demonstrate that, following SCNT in pigs, IVG culture of SAF oocytes in a medium with a reduced NaCl concentration stimulates oocyte maturation and improves subsequent embryonic development.

Tribological analysis of the plain bearings in an external gear pump

Tribological loads in the plain bearings of external gear pumps are influenced by system-specific parameters (e.g. elasticity of the components, micro-geometry and manufacturing tolerances) and the operating point (rotation speed, operating pressure and temperature of the pressure medium). Due to the pressure build-up in the tooth chambers, fluctuating radial forces are acting on the gear shafts and lead to complex deformations of the bearing bushings and the housing. These deformations have an influence on the tribological loads in the plain bearings. To decrease tribological loads and failure rates, it is possible to modify the plain bearings in terms of their micro-geometry (e.g. clearance and contours) or to take constructive measures on the overall system (e.g. on the bearing bushings). Therefore, it is necessary to understand the influences of external loads, elastic environment and micro-geometry on the tribological loads in the plain bearings. This paper describes the first steps to understand these interactions by building up a simulation model of a specific external gear pump using the MBS/EHD-tool FIRST developed by IST [1]. The focus is to evaluate the required modeling depth regarding the consideration of an elastic housing.

Estimation of pipeline systems flexible connecting pipe strength properties based on numerical study of strain-stress state

Vibration-isolating structures on rubber-cord casings are used in pipeline systems which are of great importance for the transportation of hydrocarbons. Implementation of a compensating pipe eliminates the load transfer from the pressure of the working medium to the structural elements of the pipeline. A three-dimensional model based on a numerical study and reinforced with beam elements is used to estimate the strength properties of a rubber-cord branch. The calculation of the stress-strain state of the rubber-cord casing and the flange connection of the branch pipe has been carried out. The results are to be considered when designing and operating pipe structures based on reinforced casings.

CALCULATION OF THROTTLEMENT PARAMETERS IN PARALLEL CHANNELS OF DRILLING PIPERS FOR DEEP HOLE

The article presents a method for calculating the characteristics of the throttling elements of the lubricating-cooling technical medium (COTS) Yu used in deforming piercing. A feature of the proposed technique is the method of supplying cutting fluids under pressure through the grooves made on the outer surface of the mandrel teeth, when the pressure of the working medium and its flow rate are divided into parallel flows, one of which provides pressure on the piercing when the hole is mandrelled with a normalized speed in its axial movement the second provides the calculated parameters of throttling between the surface of the grooves on the mandrel teeth and the machined surface, where they create "damping cushions", improving the mandrel process and reducing wear of the piercing [3]. The presented calculation of the characteristics (coolant pressure, flow rate, etc.) with the location of the conditional chambers formed by the grooves of the punching teeth and the processed surface confirms the possibility of using throttles to implement the conditions for using throttling elements during cutting-deforming piercing of deep holes in long tube blanks and increasing by this basis of its effectiveness.

Flexor Digitorum Brevis Muscle Dry Needling Changes Surface and Plantar Pressures: A Pre-Post Study.

Background: The effects of the dry needling technique and pain reduction have been demonstrated in numerous quality studies. However, the mechanical effects of dry needling are largely unknown. Methods: A total of 18 subjects with flexor digitorum brevis muscle myofascial trigger point were evaluated pre- and post-deep dry needling. We measured static footprint variables in a pre–post study. Main findings: We found differences in rearfoot maximum pressure (119.22–111.63 KPa; p = 0.025), midfoot maximum pressure (13.68–17.26 KPa; p = 0.077), midfoot medium pressure (4.75–6.24 KPa; p = 0.035) and forefoot surface (86.58–81.75 cm2; p = 0.020). All variables with significant differences decrease, with the exception of forefoot surface which showed an increase. Conclusions: After flexor digitorum brevis muscle dry needling, midfoot plantar pressures (maximum and medium) and forefoot surface were increased, and rearfoot maximum pressure was decreased.

Novel CFD modeling approaches to assessing urine flow in prostatic urethra after transurethral surgery

Assessment of the pressure and velocity of urine flow for different diameter ratios of prostatic urethra (RPU) after transurethral surgery using computational fluid dynamics (CFD). A standardized and idealized two-dimensional CFD model after transurethral surgery (CATS-1st) was developed for post-surgery mid-voiding. Using CATS-1st, 210 examples were amplified according to an array of size [3][5][14], which contained three groups of longitudinal diameters of prostatic urethra (LD-PU). Each of these groups contained five subgroups of transverse diameters of the bladder neck (TD-BN), each with 14 examples of transverse diameters of PU (TD-PU). The pressure and velocity of urine flow were monitored through flow dynamics simulation, and the relationship among RPU-1 (TD-PU/TD-BN), RPU-2 (RPU-1/LD-PU), the transverse diameter of the vortex, and the midpoint velocity of the external urethral orifice (MV-EUO) was determined. A total of 210 CATS examples, including CATS-1st examples, were analyzed. High (bladder and PU) and medium/low (the rest of the urethra) pressure zones, and low (bladder), medium (PU), and high (the rest of the urethra) velocity zones were determined. The rapid changes in the velocity were concentrated in and around the PU. Laminar flow was present in all the examples. The vortices appeared and then gradually shrank with reducing RPU on both the sides of PU in 182 examples. In the vortex examples, minimum RPU-1 and RPU-2 reached close to the values of 0.79 and 0.02, respectively. MV-EUO increased gradually with decreasing RPU. In comparison to the vortex examples, the non-vortex examples exhibited a significantly higher (p < 0.01) MV-EUO. The developed CFD models (CATS) presented an effective simulation of urine flow behavior within the PU after transurethral surgery for benign prostatic hyperplasia (BPH). These models could prove to be useful for morphological repair in PU after transurethral surgery.

Investigation of Aerogel Production Processes: Solvent Exchange under High Pressure Combined with Supercritical Drying in One Apparatus.

This work aims to contribute to the theoretical and experimental research of supercritical processes for intensification and combination in one apparatus. Investigation is carried out to improve production technology of organic alginate aerogels. It is proposed within the investigation to carry out the solvent exchange stage, an important stage of organic aerogels production, under pressure in a carbon dioxide medium in the same apparatus used for supercritical drying. The phase behavior in the system “carbon dioxide–water–2-propanol”, which arises during such a solvent exchange stage, is studied theoretically. An experimental study of the process of step-by-step solvent exchange under pressure was carried out through multiphase and homogeneous regions of the phase diagram of such a system. As a result, new highly efficient technology for the production of organic aerogels was proposed, which can be implemented by combining the two main stages of the process.

Development of a refractive index measurement system for vacuum pressure measurement

Many studies have recently been conducted to replace the mercury manometer that has been used as a national standard because of the prohibition of mercury. In particular, ‘the new realization of the Pascal’ by using photon technology shows some comparable results in terms of performance compared to the existing primary pressure standard based on the mercury manometer. In this study, we describe the development of a refractive index measuring system for precise vacuum pressure measurements to develop a mercury-free standard. If the refractive index of a medium is to be measured using a laser interferometer, designing a cavity as a pressure medium and a laser as a light source is important. We designed a Fabry–Perot (FP) cavity structure having two channels to calculate an arbitrary pressure by comparing the laser resonance frequency in a vacuum state, which served as a reference pressure, and that in an arbitrary pressure state. Zerodur was used as the material for the cavity. The cavity was designed to be a rectangular parallelepiped with a width of 50 mm and a length of 150 mm considering the wavelength (633 nm) of the He–Ne laser used as a light source, the pressure range to be implemented, and the implementation range of a single mode. We independently fabricated a single-mode (SM) He–Ne laser instead of a commercially available laser to modulate the frequency freely and to achieve a single polarization regardless of the quantum number. With our system, the beat frequency was measured to the internal pressure of a cavity. A 1 MHz beat frequency was found to be approximately equal to a pressure of 1 Pa.

High-efficiency catalytic wet air oxidation of high salinity phenolic wastewater under atmospheric pressure in molten salt hydrate media

Highly efficient continuous operation of an improved CWAO process coupled with desalination in MSHs via the temperature-increasing effect and common-ion salting-out effect.

Combustion characteristics of supersonic strut-cavity combustor under plasma jet-assisted combustion

Plasma jet has been widely used in supersonic combustor as an effective ignition and combustion assisted method, but currently it is mostly combined with the traditional wall fuel injection method, while the application combined with the central fuel injection method is less. In order to expand the combustion range, the plasma jet was introduced into a strut-cavity combustor with an alternating-wedge. The effects of total pressure of strut fuel injection, total pressure of cavity fuel injection, total pressure of plasma jet injection and plasma jet media on the combustion characteristics were analyzed in supersonic flow by numerical calculations in a three-dimensional domain. The combustion field structure, wall pressure distribution, combustion efficiency and distribution of H2O at the exit of the combustor with different injection conditions were analyzed. The results show that the combustion efficiency decreases with the increase of the strut fuel injection total pressure. However, the combustion area downstream increases when the total pressure of the strut fuel injection increases within the proper range. The combustion range is expanded and the combustion efficiency is improved when the cavity fuel injection total pressure is increased within the range of 0.5–2.0 MPa, but a sharp drop in combustion efficiency can be found due to limited fuel mixing when the total injection pressure of the cavity fuel is excessively increased. With the increased total injection pressure of the plasma jet, the height of the cavity shear layer is raised and the equivalence ratio of the gas mixture in the cavity is improved. When the total pressure of the plasma jet is 1.25 MPa, the combustion efficiency reaches a maximum of 82.1%. The combustion-assisted effect of different plasma jet media is significantly different. When the medium of the plasma jet is O2, the combustion-assisted effect on the combustor is most significant.

Compensation of the influence of the pressure of the working medium in sealing joints with thin-walled elements

Compensation of the influence of the pressure of the working medium in sealing joints with thin-walled elements

Preclinical study in a corneal bioreactor of the effectiveness of amniotic membrane of umbilical cord extract (AMUCE) for the treatment of corneal epithelial ulcerations

AbstractPurposeOur patented corneal bioreactor (BR) improves the survival of human corneas ex vivo in the long term by restoring intraocular pressure and renewal of storage medium in a sterile environment.AimTo use the BR to test the efficacy of eye drops containing devitalized ground amniotic membrane of umbilical cord extract (AMUCE) to treat epithelial ulcerations. AMUCE contains high level of proteoglycans, collagen and physiological growth factors.MethodsOnly pairs of human corneas were used to obtain best possible controls. They were either corneas discarded by our eye bank (cell density between 800 and 2000 cells/mm2) or specific donation for research (normal corneas). They were first stored for 2 weeks into the BR filled with CorneaMax (Eurobio, France), with 21 mmHg in the endothelial chamber to allow regeneration of a normal epithelium as previously shown. Then, a 6.0 mm diameter calibrated epithelial ulcer was made. Using a specific BR lid allowing sterile handling, each cornea was treated topically 3 times daily either by the AMUCE eye drops (TBF, France) or by the vehicle (0.9% NaCl). Closure of the ulceration was monitored daily using fluorescein staining quantified by image analysis (FIJI) of macro‐zoom microscopy. After wound healing corneas were fixed for histology (Hematein Eosin Saffron) and immunolabeling of epithelial markers.ResultsThree pairs were used. Wound healing was obtained at D3, D7, D5 with the AMUCE and D3, D6, D6 with the vehicle (no significant difference). Nevertheless, drug‐treated corneas had a thicker epithelium than with vehicle only. Histology and immunolabeling for E‐Cadherin and cytokeratin K3/K12 confirmed that epithelium of AMUCE‐treated corneas was more differentiated than with vehicle only.ConclusionsThe BR allows controlled studies of epithelial wound healing on human corneas with repeated instillations. By improving epithelial maturation, AMUCE eye drop is an interesting candidate for epithelium regeneration.