Showing papers in "High Pressure Research in 2012"
TL;DR: Alicyclobacillus acidoterrestris, a thermoacidophilic and spore-forming bacterium is one of the important target microorganisms in the quality control of acidic canned foods as mentioned in this paper.
Abstract: Alicyclobacillus acidoterrestris, a thermoacidophilic and spore-forming bacterium is one of the important target micro-organisms in the quality control of acidic canned foods. High pressure pasteurization (HPP) at 50°C was used for the inactivation of A. acidoterrestris spores in apple juice. Pressure applied both in a continuous and oscillatory mode gave the best results when 200 MPa was used. Increasing the pressure to 500 MPa, as well as lowering its value to 100 MPa, had an adverse effect on the effectiveness of the process. The best results were achieved with the use of a combined treatment, involving oscillatory pressurization at 200 MPa, followed by holding the sample for 60 min at atmospheric pressure and subsequent pressurization at 500 MPa, resulting in a reduction in the spore count of 6.15 log. Nisin significantly enhanced the effect of HPP at 300 MPa. Using pressure of 200 MPa for 45 min with a nisin concentration of 250 IU/mL enabled total spore inactivation (over 6 log). No significant effe...
51 citations
TL;DR: In this paper, a systematic study of solid-state phase transformations between boron polymorphs: α -B12, β -B106, γ -B28, T-B52, β-B12 and amorphous Boron (am-B) is presented.
Abstract: Here we report the systematic study of solid-state phase transformations between boron polymorphs: α -B12, β -B106, γ -B28, T-B52 and amorphous boron (am-B). It is evident that the Ostwald rule of stages plays an important role during phase transformations not only of amorphous boron, but also of crystalline forms. We have observed the crystallization of tetragonal boron T-B52 from amorphous phase of high purity (99.99%), which, however, cannot be easily distinguished from B50C2 boron compound. Many factors influence the transformations of amorphous phase, and it is possible to observe not only well-known am-B → α -B12 and am-B → β -B106 transformations, but also am-B → T-B52, never reported so far. At ∼14 GPa, the crystallization order becomes β -B106→α -B12→γ -B28, while at ∼11 GPa the intermediate crystallization of T-B52 still was observed. This unambiguously indicates that α -B12 is more thermodynamically stable than β -B106 at high pressures (HPs) and renders possible to transform, at least partiall...
31 citations
TL;DR: A massive cubic press with a maximum load of 1400 tons on every WC anvil has been installed at the High Pressure Laboratory of Peking University as discussed by the authors, where the experimental results suggest that the conventional experimental setup (assembly BJC2-0) can reach pressures up to about 6-GPa with a large cell volume of 34.33
Abstract: A massive cubic press, with a maximum load of 1400 tons on every WC anvil, has been installed at the High Pressure Laboratory of Peking University. High-P experiments have been conducted to examine the performance of the conventional experimental setup and some newly developed assemblies adopting the anvil-preformed gasket system. The experimental results suggest that (1) the conventional experimental setup (assembly BJC2-0) can reach pressures up to about 6 GPa with a large cell volume of 34.33 cm3; (2) the anvil-preformed gasket system, despite decreasing the P-generating efficiency, extends the P-generating capability up to about 8 GPa at the expense of reducing the cell volume down to 8.62 cm3 (assembly BJC2-6); (3) due to the large cell volume, it is possible to make further modifications to extend the pressure range, as readily demonstrated, to about 10 GPa (assembly BJC5-7); (4) the effect of high temperature on the pressure generation of the press is not significant. It follows that this cubic pre...
30 citations
TL;DR: In this paper, the shelf life of probiotic Lactobacillus casei 01 was studied and the longan juice was subjected to a high pressure of 500MPa for 30min and compared with a juice pasteurized at 90°C/2min.
Abstract: In this study, longan juice was subjected to a high pressure of 500 MPa for 30 min and compared with a juice pasteurized at 90°C/2 min. Probiotic Lactobacillus casei 01 was fortified into both juices and the shelf life of these products was studied. Their bioactive components such as ascorbic acid, gallic acid and ellagic acid were analyzed by High Performance Liquid Chromatography (HPLC). Total phenolic compounds and 2,2-Diphenyl-1-picrythydrazyl radical-scavenging activity were determined by colorimetric and spectrophotometric methods. It was found that the pressurized longan juice retained higher amounts of bioactive compounds than the pasteurized juice. In terms of storage stability, bioactive compounds in both processed juices decreased according to the increase in storage time. The survivability of probiotic L. casei 01 in both processed juices declined from 9 to 6 log CFU/mL after 4 weeks of storage.
30 citations
TL;DR: In this paper, the design of new high pressure equipment for structural and dynamical studies on samples in solution is described, and two sample cells for applying pressures up to 150 and 700 MPa (i.e. 1.5 and 7 MPa), respectively, are mounted on special sticks and inserted into the calorimeter of a cryostat to regulate the temperature.
Abstract: The design of new high pressure equipment for structural and dynamical studies on samples in solution is described. We present two sample cells for applying pressures up to 150 and 700 MPa (i.e. 1.5 and 7 kbar), respectively. These cells are mounted on special sticks and inserted into the calorimeter of a cryostat to regulate the temperature. Different parts of the equipment – the pressure controller, the sticks and the cells – are described. In addition, radiography tests which were performed with neutrons in situ at the Institut Laue Langevin to verify the tightness of the cells and the hydrostatic transmission of the pressure to the sample are presented. First results on model lipids are in agreement with former results by R. Winter et al. [Towards an understanding of the temperature/pressure configurational and free-energy landscape of biomolecules, J. Non-Equilib. Thermodyn. 32 (2007), pp. 41–97].
29 citations
TL;DR: In this article, the structure of Bi-IV at 3.2 GPa and 465 K was investigated by single-crystal synchrotron X-ray diffraction.
Abstract: Bi-IV is the stable high-pressure, high-temperature phase of bismuth at ∼4 GPa and ∼500 K. It was first identified in 1958, but its structure has remained uncertain. An X-ray powder-diffraction study of Bi-IV reported the structure as monoclinic, but a subsequent reinterpretation of the same data concluded that the structure was C-centred orthorhombic (oC16), with the same atomic arrangement as in Cs-V and Si-VI. To resolve the uncertainty over the structure of Bi-IV, we investigated this phase at 3.2 GPa and 465 K by single-crystal synchrotron X-ray diffraction. All of the observed reflections could be indexed on the orthorhombic oC16 structure proposed by Degtyareva, with a=11.191(5) A, b=6.622(1) A and c=6.608(1) A. The spacegroup was confirmed as Cmce. Refinement of the data resulted in an excellent fit (R=2.8% ), and gave atomic coordinates very similar to those of the oC16 structures in Cs-V and Si-VI.
25 citations
TL;DR: In this paper, the generation of nanoparticles (NPs) has been developed by performing PLA of silver (Ag) plates in a supercritical CO2 medium with an excitation wavelength of 532 nm under various pressures and temperatures.
Abstract: Pulsed laser ablation (PLA) has been widely employed in industrial and biological applications and in other fields. The environmental conditions in which PLA is conducted are important parameters that affect both the solid particle cloud and the deposition produced by the plume. In this work, the generation of nanoparticles (NPs) has been developed by performing PLA of silver (Ag) plates in a supercritical CO2 medium. Ag NPs were successfully generated by allowing the selective generation of clusters. Laser ablation was performed with an excitation wavelength of 532 nm under various pressures and temperatures of CO2 medium. On the basis of the experimental result, both surface of the irradiated Ag plate and structure of Ag NPs were significantly affected by the changes in supercritical CO2 pressure and temperature. With increasing irradiation pressure, plume deposited in the surrounding crater created by the ablation was clearly observed. In Field Emission Scanning Electron Microscopy (FE-SEM) the image o...
25 citations
TL;DR: In this article, the total amount of proteins (TAPs) extracted by high hydrostatic pressure processing (HHPP) was measured and compared with the results of the conventional extraction method (CEM).
Abstract: Even a single peptide that is present in the pollen wall and cytoplasm could cause pollen allergy. To produce skin-prick test kits, the first step is the extraction of these molecules. In this study, Cedrus atlantica pollens were subjected to 220 and 330 MPa for 10 and 30 min in order to extract these molecules. After high hydrostatic pressure processing (HHPP), the total amounts of proteins (TAPs) are measured and compared with the results of the conventional extraction method (CEM). As a result, the TAPs extracted by HHPP is 18.0210 μ g/mL at 220 MPa for 10 min, 22.5770 μ g/mL at 220 MPa for 30 min, 23.3810 μ g/mL at 330 MPa for 10 min and 25.9270 μ g/mL at 330 MPa for 30 min, while this is 1.9460 μ g/mL in 24 h by the CEM. In addition to these results, visual pollen deformation and eruption, pollen wall and surface damage have also been observed.
24 citations
TL;DR: In this article, the elastic properties of high quality ZnO crystals and nanopowder of grain size of about 65nm are studied for both wurtzite (low pressure) and rock-salt high pressure phases.
Abstract: The elastic properties of high-quality ZnO crystals and nanopowder of grain size of about 65 nm are studied for both wurtzite (low pressure) and rock-salt high pressure phases. The measured values of bulk moduli for wurtzite and rock-salt phases of bulk ZnO crystals are equal to 156±13 and 187±20 GPa, respectively, and considerably larger for ZnO nanocrystals. The phase transition begins at a pressure of about 9 GPa and it is completed at a pressure of about 13.8 GPa for bulk crystals, whereas the values of pressure at which the phase transition occurs are lower for nanocrystals. A carefull Rietveld analysis of the obtained data does not exhibit the presence of any intermediate phases between low pressure wurtzite and high pressure rock-salt phases of ZnO. The phase transition is accompanied by a strong decrease in the near-band-gap photoluminescence intensity. In addition, the pressure coefficient of the near-band-gap luminescence in ZnO nanocrystals exhibits strong deviation from the linearity observed ...
23 citations
TL;DR: A hybrid pressure cell of pyrophyllite and magnesium oxide (HPCPM) was used in large volume cubic presses as discussed by the authors, and the results indicated that the pressure generation efficiency was improved by about 40% without decreasing the anvil truncation size.
Abstract: A hybrid pressure cell of pyrophyllite and magnesium oxide (HPCPM) used in large volume cubic presses is presented In the HPCPM, a cubic frame which is made of pyrophyllite with face-centered square holes works as gaskets, and a heteromorphosis magnesium oxide works as the pressure-transmitting medium Our experimental results indicated that the pressure-generation efficiency using the HPCPM was improved by about 40% than that using the traditional pyrophyllite pressure cell without decreasing the anvil truncation size (without sacrificing the sample volume) The HPCPM could pressurize samples of 1000 mm3 volume up to about 8 GPa, which is significantly higher than that available using the traditional pressure cell, which reports a highest pressure of about 6 GPa
22 citations
TL;DR: In this article, the conical aperture of Ni-bounded WC anvils was expanded by a factor of two and a hybrid gasket made of TiZr-and Al-alloy was developed to prevent outward extrusion.
Abstract: We designed new anvil assemblies for acquiring high-quality neutron diffraction data and ruby fluorescence spectra inside a sample chamber. The conical aperture of Ni-binded WC anvils was expanded by a factor of two. A hybrid gasket made of TiZr- and Al-alloy was developed to prevent outward extrusion. A small and optically transparent window of moissanite was introduced to allow for the determination of pressure and hydrostaticity by measurement of ruby fluorescence spectra. High pressure-generation tests that make use of Bi electrical conductivity and ruby pressure markers revealed that pressure could be determined over 10 GPa. In situ synchrotron X-ray diffraction experiments were also carried out using NaCl as the pressure calibrants. The maximum pressure achieved was approximately 13 GPa. The neutron diffraction intensity from the newly generated anvil assemblies was 2.5–3.0 times greater than that using the standard toroidal anvil assemblies used previously.
TL;DR: In this paper, a large volume multi-anvil system which employs six independently acting hydraulic rams with independent oil pressurization systems has been developed for high pressure and temperature experiments, where the position of each anvil relative to the press frame can be precisely measured and controlled independently, thus ensuring a high level of symmetry in the compressive stress environment.
Abstract: A new large volume multi-anvil system which employs six independently acting hydraulic rams with independent oil pressurization systems has been developed for high pressure and temperature experiments. The six 8 MN hydraulic rams approach at right angles inside a composite steel plate frame and can each advance a square faceted anvil of either hardened steel or tungsten carbide. The position of each anvil can be measured relative to the frame of the press to a precision of 0.1 μ m. The press is designed to perform both deformation experiments using cubic ceramic pressure media and experiments employing eight inner cubic anvils to compress an octahedral pressure medium. During compression, the position of each anvil relative to the press frame can be precisely measured and controlled independently, thus ensuring a high level of symmetry in the compressive stress environment. The highly cubic compressive regime provides an optimal environment for the use of inner sintered diamond cubic anvils, which can pot...
TL;DR: In this article, the biologically active constituents of pennywort juice were analyzed by HPLC and the juice extract contained the bioactive glycosides, including asiaticoside and madecassoside.
Abstract: The biologically active constituents of pennywort juice were analyzed by HPLC. The juice extract contained the bioactive glycosides, including asiaticoside and madecassoside. Antioxidant properties of juices were determined in terms of ferric-reducing antioxidant power assay, total polyphenol, β-carotene and ascorbic acid contents. After processing, asiaticoside, madecassoside and β-carotene in the extracted juice were relatively stable with no significant losses occurring. Pressurization could significantly retain ascorbic acid, polyphenols and antioxidant capacity than those pasteurization or sterilization. For storage assessment, asiaticoside in the processed juices was relatively stable during 4 months storage. Losses of ascorbic acid in the pressurized juice during storage were greater than in pasteurized and sterilized juice. However, the total amount of ascorbic acid retained in pressurized juice was still higher than those thermal-treated products.
TL;DR: In this paper, the superconducting properties of raw MgB2 wires have been investigated by means of four-probe critical current j c measurement, which provided place for samples 70 mm long in parallel field and 20mm long in perpendicular field.
Abstract: Raw MgB2 wires have been manufactured by Hyper Tech Inc. Each of their 18 cores contained undoped in situ powder surrounded by an Nb barrier and placed in a Cu sheath, and cores were coated in a common Monel sheath. Wires of diameters 0.63 and 0.83 mm were annealed under high argon pressure (up to 1 GPa). Parameters of such HIP process (temperature, time, and pressure) were varied in order to determine their optimal values. Superconducting properties of such samples were investigated by means of four-probe critical current j c measurement. Bitter magnet producing magnetic field up to 14 T was used. It provided place for samples 70 mm long in parallel field and 20 mm long in perpendicular field. Results include critical current j c and pinning force density F p dependencies on magnetic field as well as Kramer plots. Critical current of 104 A/cm 2 was achieved at 12 T magnetic field. SEM pictures of wire cross sections were also taken to determine quality of Nb barrier and microstructure of superconducting ...
TL;DR: In this paper, the influence of high pressure treatment on the structural changes and allergenicity of largemouth bass was studied, and the greatest structure changes were found for samples treated by 400MPa for 15min.
Abstract: The aim of this paper is to study the influence of high pressure treatment on the structural changes and allergenicity of largemouth bass. We treated the allergens at 100, 200, 300 and 400 MPa for 15 min and at 300 MPa for 5, 10, 15, 20 and 30 min at 20 °C. The treated samples from largemouth bass were tested for their IgE-binding properties by combining Sodium dodecyl sulfate-Polyacrylamide gel electrophoresis (SDS-PAGE) with western blotting (WB) and enzyme-linked immunosorbent assay (ELISA). Circular dichroism analysis was performed to characterize the structural change. In summary, we can determine that the greatest structure changes were found for samples treated by 400 MPa for 15 min. High pressure treatment did change the structure, subunit composition and molecular weight of largemouth bass allergens, but it did not change the allergenicity of the allergens.
TL;DR: In this article, the color change in lychee was investigated by high pressure and thermal processing. But the results showed that the results indicated that high pressure could reduce the activity of polyphenoloxidase by 33-51%, whereas pasteurization markedly reduced that activity by 90%.
Abstract: Lychee usually has white flesh, but its flesh is very sensitive to thermal and enzymatic impairment and ultimately changes in color. This investigation was intended to study the magnitude of color change in lychee by high pressure and thermal processing. The lychee was packed in syrup prior to being processed. Pressurized lychee was performed at 600 MPa at 30°C or 50°C for 20 min, while the pasteurized sample was heated at 90°C for 3 min. It was found that pressurization induced lower color L*, a* and b* values, including low anthocyanin content. For enzymatic activities, high pressure could reduce the activity of polyphenoloxidase by 33–51%, whereas pasteurization markedly reduced that activity by 90%.
TL;DR: In this article, the evolution of the BaSO4 cation array with pressure was studied and a rational description of the structure was provided for the BaS array with respect to the phase transition at 27 GPa to a new structure type.
Abstract: The aim of this paper is to contribute to a better understanding of the behaviour of mineral barite, BaSO4, at high pressures, particularly the recently reported phase transition at 27 GPa to a new structure type For this purpose, we will focus on the evolution of its BaS cation array with pressure, which will additionally allow for a rational description of the structure When the initial Pnma barite structure transforms into the also orthorhombic P212121 structure, no change in the coordination number of Ba or S atoms occurs ([SO4] tetrahedra and [BaO12] dodecahedra) However, the second coordination sphere presents an increase of neighbour atoms and a decrease of the Ba–S distances This rearrangement of atoms is related to the Buerger's mechanism of the B1–B2 phase transition for the BaS cation array, confirming that cations (second neighbours) do not arrange in an arbitrary way
TL;DR: In this article, the high pressure phase of aluminium nitride with rocksalt structure (rs) was synthesized and recovered by shock wave experiments using the flyer-plate method with multiple reflections at peak pressures between 15 and 43 GPa.
Abstract: The high pressure phase of aluminium nitride with rocksalt structure (rs) is a ceramic with high potential and a challenging material to investigate. The rs-AlN was synthesised and recovered by shock wave experiments using the flyer-plate method with multiple reflections at peak pressures between 15 and 43 GPa. Successful syntheses were carried out using AlN nanopowder with ambient pressure wurtzite structure (w-AlN) as starting material. The high pressure modification could, however, not be obtained when starting from submicron w-AlN. The recovery of rs-AlN is sensitive to the synthesis conditions as these influence the reconversion of rs-AlN to w-AlN.
TL;DR: In this article, near and supercritical CO2 were used as media for the electrospinning process of polyvinylpyrrolidone (PE) fibers, and the applied voltage was 10−17kV and the distance of nozzle and collector was 8 cm.
Abstract: Electrospinning is one of the simple technical methods for the production of polymer nanoparticles and nanofibers. Various polymers have been successfully electrospun into ultrafine particles and fibers in recent years mostly in solvent solution and some in melt form. In this work, near- and supercritical CO2 were used as media for this process. At these conditions, the solubility can be tuned by controlling the temperature and pressure. Therefore, it is possible to form particles and fibers within a thermodynamic window where the biopolymer has been softened, but not dissolved. The experiments were conducted by using electrospinning under pressurized CO2 system at pressures of ∼ 8.0 MPa and temperature of 313 K to produce several polymers fibers. Polyvinylpyrrolidone was used as the starting material. During the electrospinning process, the applied voltage was 10–17 kV and the distance of nozzle and collector was 8 cm. The concentration of polymer solution was 4 wt%. The morphology- and structure-produce...
TL;DR: In this paper, the sintering behavior and mechanical properties of cubic boron nitride (cBN) composites, using the mixture of cBN-Ti3Al and cBN− Ti3Al-Al as the starting material respectively, were investigated under high pressure and high temperature (HPHT) conditions.
Abstract: The sintering behavior and mechanical properties of cubic boron nitride (cBN) composites, using the mixture of cBN–Ti3Al and cBN–Ti3Al-Al as the starting material respectively, were investigated under high pressure and high temperature (HPHT) conditions. The results show that the samples of cBN–Ti3Al-Al sintering system have more homogeneous microstructures. Young's modulus, shear modulus, and bulk modulus of samples measured by ultrasonic measurements can reach to 782±3 GPa, 344±1 GPa, and 348±2 GPa, respectively. The hardness increases remarkably with the sintering temperature rising, and reaches to the highest value of 35.04±0.51 GPa. For the cBN–Ti3Al sintering system, the X-ray diffraction patterns of composites reveal that the chemical reactions between cBN and Ti3Al occurred at 5.0 GPa and 1300°C. The reaction mechanisms of both cBN–Ti3Al and cBN–Ti3Al-Al sintering systems are discussed in this paper.
TL;DR: In this article, the authors artificially infected liquid whole egg samples with Salmonella enteritidis, Listeria monocytogenes, and Staphylococcus aureus bacteria, and then treated the samples in “Food Lab900” high hydrostatic pressure (HHP) instrument for 3-17min at 200-400 MPa.
Abstract: In our tests, we artificially infected liquid whole egg samples with Salmonella enteritidis, Listeria monocytogenes, and Staphylococcus aureus bacteria, and then treated the samples in “Food Lab900” high hydrostatic pressure (HHP) instrument for 3–17 min at 200–400 MPa. Subsequently, the change of the viable cell count of the specific bacteria has been tested. In addition to the samples infected with various bacteria, non-infected samples were also treated in each test and the change in viable cell count, colour and viscosity of the samples upon the effect of the treatment. In summary, it can be concluded that in each test of our investigations, the viable cell count of S. enteritidis critical for egg products is reduced significantly, while the reduction of the total viable cell count was around two magnitudes. Additionally, based on our results, microbial destruction, reduction of enthalpy (denaturation of egg white) caused by the treatment at HPP, and colour change are primarily affected by the pressur...
TL;DR: In this article, a sample assembly of the sample for ultrasonic measurements is designed under HPHT, which can prevent plastic deformation, and the relation of sample temperature and temperature measured by thermocouple can also be determined.
Abstract: Under high-temperature and high pressure (HTHP) experiments, materials of small elastic modulus deform easily, and the length of the sample can be hardly predicted which lead to failure of ultrasonic velocity measurement. In this paper, a hydrostatic assembly of the sample for ultrasonic measurements is designed under HPHT, which can prevent plastic deformation. According to the abrupt change of travel time of the sample across the different phase boundaries of bismuth, the correspondent relation of sample pressure and oil pressure of multi-anvil apparatus can be calibrated, and the relation of sample temperature and temperature measured by thermocouple can also be determined. Sample pressure under high temperature is also determined by ultrasonic results. It is believed that the new sample assembly of hydrostatic pressure is valid and feasible for ultrasonic experiments under HTHP.
TL;DR: In this article, the optical properties of TlInS2 layered ferroelectric with an incommensurate phase were studied in the temperature range 190-220 k at atmospheric pressure.
Abstract: Studies of the optical properties of TlInS2 layered ferroelectric with an incommensurate phase were performed. In the temperature range 190–220 K at atmospheric pressure, we observed rotation of the plane of the optical axes and a change of the angle between the optical axes of the crystal. The temperature dependences of birefringence and its anomalous part were investigated, the anomalies at T c =192 K and T i =214 K, corresponding to structural phase transitions, were revealed. Pressure increase in the range p atm≤p<470 MPa is shown to result in a shift of the birefringence anomalies towards higher temperatures.
TL;DR: In this article, a first-order phase transition of a DAG sample was observed in high pressure conditions and the threshold value of the pressure for the phase change was determined, and a number of further measurements were performed.
Abstract: A sample of diacylglycerol (DAG) oil, being a mixture of DAGs and triacylglycerols with a ratio of 82% and 18%, respectively, and with a vestigial content of monoacylglycerols and free fatty acids, has been researched in high pressure conditions. As a result of dynamically applied pressure, a discontinuous (first-order) phase transition of the DAG sample has been observed. After the threshold value of the pressure for the phase change was determined, a number of further measurements were performed. The aim of the measurements was to pressurise the DAG sample with different rates of compression. During the measurements, the following parameters were recorded: the intensities of beams both transmitted and scattered at the angle of 90°, and the temperature of the sample. The obtained data may prove useful for an introductory description of the phase change kinetics induced by dynamically applied pressure.
TL;DR: The elastic properties of hydrous iron-bearing wadsleyite (Mg1.75Fe0.25SiO4) at high pressures are investigated using first-principles calculations.
Abstract: The elastic properties of hydrous iron-bearing wadsleyite (Mg1.75Fe0.125H0.25SiO4) and hydrous iron-bearing ringwoodite (Mg1.75Fe0.125H0.25SiO4) at high pressures are investigated using first-principles calculations. Hydration reduces the elastic moduli and wave velocities of wadsleyite and ringwoodite. Incorporation of 6.25 mol% iron insignificantly affects the bulk moduli, but reduces the shear moduli by 5.33 and 4.80 GPa in average for wadsleyite and ringwoodite, respectively. The compressional wave velocities of iron-bearing wadsleyite and iron-bearing ringwoodite decrease by an average 2.20% and 1.96% at pressures from 0 to 30 GPa, and the shear wave velocities decrease by an average 3.58% and 3.17%, respectively. Compared with the elastic moduli and wave velocities of dry, hydrous, and iron-bearing wadsleyite/ringwoodite, those of coexistence of iron and water decrease most. Adding simultaneously 6.7 mol% iron and 1.6 wt% water leads to decrease in the bulk(shear) modulus by 5.57%(7.80%) and 5.84%(4...
TL;DR: In this article, a simple high-temperature high pressure cell concept has been developed to enable neutron diffraction and quasi-elastic and inelastic neutron-scattering studies to be conducted on large-volume powder samples of ceramic proton conductors at pressures of up to 1 ǫa and at temperatures of up 770 k.
Abstract: In this study, a simple high-temperature high pressure cell concept has been developed to enable neutron diffraction and quasi-elastic and inelastic neutron-scattering studies to be conducted on large-volume powder samples of ceramic proton conductors at pressures of up to 1 GPa and at temperatures of up to 770 K. Details of the cell are provided, along with the first experimental neutron diffractograms (at 0.62 GPa and 300 K), quasi-elastic neutron-scattering spectra (at 0.58 GPa and 770 K) and inelastic neutron spectra (at 0.75 GPa and 530 K) determined for samples of BaCe0.8Y0.2O3.
TL;DR: In this paper, the positions of elastic plastic interfaces of the autofrettaged pressure vessels were identified and the results revealed that the residual strain magnitude and the depth of the plastic region will increase with increasing auto-rettage pressure level.
Abstract: Positions of elastic plastic interfaces play a vital role in safe design and safe use of high pressure vessels. The ENGIN-X neutron diffractometer at the ISIS facility was used to measure the residual strain profiles in a series of aluminium vessels which had been subjected to different pressure levels. The positions of elastic plastic interfaces of the autofrettaged pressure vessels were identified. The results revealed that the residual strain magnitude and the depth of the plastic region will increase with increasing autofrettage pressure level. When autofrettage pressure produces an elastic-plastic boundary at a greater depth than the geometric mean position of the vessel wall, reverse yielding will occur, hence the loss of the vessels’ elastic ability to its subsequent loading. The neutron experimental results agreed well with both the suggestions from existing literatures and the results from FE simulations.
TL;DR: In this paper, a diamond anvil with a spherical support was designed for applications in diamond cell (DAC) technique, where the main feature of the anvils is the diamond crown of a spherical shape.
Abstract: Here, we present new diamond anvils with a spherical support designed for applications in diamond anvil cell (DAC) technique. The main feature of the anvils is the diamond crown of a spherical shape. The assembly of the spherical diamond fixed within a spherical support of a seat made of tungsten carbide or hard metals provides enhanced stability, simple alignment, and large optical and X-ray aperture that makes it very useful for broad applications in DAC technique, particularly for single crystal X-ray and powder neutron diffraction. The anvils were tested in various experiments conducted in a wide pressure–temperature range and showed a very good performance.
TL;DR: The martensite tetragonal-to-monoclinic transition of the partially stabilized zirconia nanoparticles under hydrostatic pressure (100-1000 MPa) was investigated in this paper.
Abstract: The surface state of partially stabilized zirconia with nanoparticles of sizes 10–30 nm after temperature and pressure treatments was investigated by Fourier transform infrared spectroscopy, X-ray diffraction and small-angle X-ray scattering. It is shown that the synthesized nanoparticles are surface fractals and the fractal dimensions non-monotonically change with nanoparticles size change. The martensite tetragonal-to-monoclinic transition of the partially stabilized zirconia nanoparticles under hydrostatic pressure (100–1000 MPa) was investigated. It was shown that the character of the martensite transition in nanoparticles’ system depends on the pressure values. Three ranges of pressures were revealed. It was shown that the stability of martensite tetragonal–monoclinic transition decreases with the increase in size of the nanoparticles only for the pressures range of 300–500 MPa. Below 200 MPa, the character of the martensite transition is extreme and has a maximum for the particle size of 17 nm. In p...
TL;DR: In this paper, a first-principles investigation on the crystal structural and elastic properties and the equation of state of wurtzite-type cadmium selenide (w-CdSe) has been conducted using the plane-wave pseudo-potential density functional theory and the quasi-harmonic Debye model.
Abstract: A first-principles investigation on the crystal structural and elastic properties and the equation of state of wurtzite-type cadmium selenide (w-CdSe) has been conducted using the plane-wave pseudo-potential density functional theory and the quasi-harmonic Debye model. The elastic constants, the aggregate elastic moduli, the elastic anisotropy, and Poisson's ratio under pressure have been investigated. Our calculated equilibrium lattice constants, the elastic constants, and the aggregate elastic moduli at zero pressure are in good agreement with the experimental data and other theoretical results. The variations in the compressional and shear elastic wave velocities with pressure at zero temperature up to pressure 2.7 GPa have been studied; the computed Debye temperature at zero pressure and zero temperature is in reasonable agreement with the result of Bonello et al., In addition, the equation of state of w-CdSe in the pressure range of 0–2.7 GPa and up to a temperature of 900 K has also been obtained.