Showing papers in "High Pressure Research in 2017"
TL;DR: In this paper, a low background double-wall piston-cylinder-type pressure cell is developed at the Paul Scherrer Institute, which is made from BERYLCO-25 and MP35N nonmagnetic alloys with the design and dimensions adapted to muon-spin rotation/relaxation (μSR) measurements.
Abstract: A low background double-wall piston–cylinder-type pressure cell is developed at the Paul Scherrer Institute. The cell is made from BERYLCO-25 (beryllium copper) and MP35N nonmagnetic alloys with the design and dimensions which are specifically adapted to muon-spin rotation/relaxation (μSR) measurements. The mechanical design and performance of the pressure cell are evaluated using finite-element analysis (FEA). By including the measured stress-strain characteristics of the materials into the finite-element model, the cell dimensions are optimized with the aim to reach the highest possible pressure while maintaining the sample space large (6 mm in diameter and 12 mm high). The presented unconventional design of the double-wall piston–cylinder pressure cell with a harder outer MP35N sleeve and a softer inner CuBe cylinder enables pressures of up to 2.6 GPa to be reached at ambient temperature, corresponding to 2.2 GPa at low temperatures without any irreversible damage to the pressure cell. The natu...
32 citations
TL;DR: In this paper, a review of some important technical challenges related to in situ diamond anvil cell laser heating experimentation at synchrotron X-ray sources is presented, where the problem of potential chemical reactions between the sample and the pressure medium or the carbon from the diamond Anvils is illustrated in the case of elemental tantalum.
Abstract: A review of some important technical challenges related to in situ diamond anvil cell laser heating experimentation at synchrotron X-ray sources is presented. The problem of potential chemical reactions between the sample and the pressure medium or the carbon from the diamond anvils is illustrated in the case of elemental tantalum. Preliminary results of a comparison between reflective and refractive optics for high temperature measurements in the laser-heated diamond anvil cell are briefly discussed. Finally, the importance of the size and relative alignment of X-ray and laser beams for quantitative X-ray measurements is presented.
31 citations
TL;DR: In this paper, the electrical resistivity of high purity Zn along the melting boundary, up to 5'GPa in a large volume press, was measured and the electronic thermal conductivity was calculated from resistivity data using the Wiedemann-Franz law and shows a decrease with temperature in the solid state and an increase in the liquid state.
Abstract: We measured the electrical resistivity of high purity Zn along the melting boundary, up to 5 GPa in a large volume press. The electrical resistivity remained constant on the melting boundary, as predicted in a thermodynamics-based model for simple metals. The effects of pressure and temperature on the electrical resistivity of the solid and liquid states are interpreted in terms of their antagonistic effects on the electronic structure of Zn. Within the error of measurements, our melting temperature data agree well with those of the previous studies. The electronic thermal conductivity was calculated from resistivity data using the Wiedemann–Franz law and shows a decrease with temperature in the solid state and an increase in the liquid state, with a large decrease on melting. Comparison of calculated electronic and measured total thermal conductivities indicates that the electronic component dominates over the phonon component in Zn.
31 citations
TL;DR: In this article, the authors investigated the effect of high hydrostatic pressure on beetroot juice quality and showed a significant reduction of the number of spoilage microorganisms with a slight degradation of pigments.
Abstract: Freshly squeezed commercially available beetroot juice, a popular beverage in Poland, is a good source of betalains, but as a root vegetable can contain undesirable microflora from the soil. The objective of this study was to investigate the effect of new preservation technique, high hydrostatic pressure, on the beetroot juice quality. Samples of beetroot juice were treated with pressure 300, 400 and 500 MPa/20°C/up to 10 min. Reduction in the total count of spoilage microorganisms reached 3.8, 4.1 and 4.5 log cfu/mL, depending on the pressure. After this treatment beetroot juice showed a 11.3–12.2% decrease in betacyanins content and 7.7–8.9% in betaxanthins content. A significant reduction of the number of spoilage microorganisms with a slight degradation of pigments indicates the possibility of industrial application of high pressure to the preservation of beetroot juice.
25 citations
TL;DR: In this article, a Kawai-type multi-anvil apparatus (KMA) using tungsten carbide (WC) anvils with a high hardness of Hv = 2700 and a Young's modulus of 660 GPa was used for studying the upper part of the Earth's lower mantle down to 1200 km depth.
Abstract: We have expanded the pressure ranges at room and high temperatures generated in a Kawai-type multi-anvil apparatus (KMA) using tungsten carbide (WC) anvils with a high hardness of Hv = 2700 and a Young’s modulus of 660 GPa. At room temperature, a pressure of 64 GPa, which is the highest pressure generated with KMA using WC anvils in the world, was achieved using 1°-tapered anvils with a 1.5-mm truncation. Pressures of 48–50 GPa were generated at high temperatures of 1600–2000 K, which are also higher than previously achieved. Tapered anvils make wide anvil gaps enabling efficient X-ray diffraction. The present pressure generation technique can be used for studying the upper part of the Earth’s lower mantle down to 1200 km depth without sintered diamond anvils.
19 citations
TL;DR: In this article, the response surface methodology (RSM) was employed for the first time to optimize high pressure extraction (HPE) conditions of bioactive compounds from pansies, namely: pressure (X1: 0-500 MPa), time (X2: 5-15 min), and ethanol concentration (X3: 0 -100%).
Abstract: Response surface methodology (RSM) was employed for the first time to optimize high pressure extraction (HPE) conditions of bioactive compounds from pansies, namely: pressure (X1: 0–500 MPa), time (X2: 5–15 min) and ethanol concentration (X3: 0–100%). Consistent fittings using second-order polynomial models were obtained for flavonoids, tannins, anthocyanins, total reducing capacity (TRC) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity. The optimum extraction conditions based on combination responses for TRC, tannins and anthocyanins were: X1 = 384 MPa, X2 = 15 min and X3 = 35% (v/v) ethanol, shortening the extraction time when compared to the classic method of stirring (approx. 24 h). When the optimum extraction conditions were applied, 65.1 mg of TRC, 42.8 mg of tannins and 56.15 mg of anthocyanins/g dried flower were obtained. Thus, HPE has shown to be a promising technique to extract bioactive compounds from pansies, by reducing the extraction time and by using green solve...
19 citations
TL;DR: Zhu et al. as discussed by the authors showed that the stability of several intermetallic compounds, including XeNi3 and XeFe3, has been recently calculated using structural searches and density functional theory above 155 and 190 GPa, respectively.
Abstract: Xe–Ni and Xe–Fe systems are studied in a pressure range relevant to the Earth's core (135–210 GPa) using laser-heated diamond anvil cells and synchrotron X-ray diffraction. The stability of several intermetallic compounds, including XeNi3 and XeFe3, has been recently calculated using structural searches and density functional theory (DFT) above 155 and 190 GPa, respectively [Zhu L, Liu H, Pickard CJ, et al. Nat Chem. 2014;6:644–648]. We have synthesized XeNi3 around 150 GPa, confirming the prediction; however, it has a cubic Pm3¯m-Cu3Au structure, different from the predicted one for XeNi3 but identical to the structure predicted for XeFe3. Pm3¯m-XeNi3 is calculated to be metastable with DFT. A disordered Ni1−xXex (x∼0.08) alloy is observed to form prior to this compound. This alloy is interesting in the perspective of a possible storage of xenon in the Earth's core. We have not observed any reaction between Xe and Fe up to 210 GPa.
19 citations
TL;DR: In this paper, a diamond cell with extreme apertures is described for a large variety of neutron scattering techniques such as inelastic neutron scattering and single-crystal diffraction.
Abstract: A new diamond cell with extreme apertures is described. It is tailored for a large variety of neutron scattering techniques such as inelastic neutron scattering and single-crystal diffraction both ...
18 citations
TL;DR: In this article, the effect of high hydrostatic pressure (HHP) treatment (200, 300, 400, MPa; 5°C, 15°C and 25°C; 5 and 10 min) on some quality properties of pomegranate juice was investigated.
Abstract: The aim of this study was to investigate the effect of high hydrostatic pressure (HHP) treatment (200, 300, 400 MPa; 5°C, 15°C and 25°C; 5 and 10 min) on some quality properties of pomegranate juice. Juice samples are obtained under industrial conditions at two different squeezing pressure levels (100 and 150 psi – 0.689 and 1.033 MPa, respectively). Results are compared against conventional thermal treatment (85°C/10 min) and raw sample. For all three processing temperature, HHP combinations at 400 MPa for 10 min were sufficient to decrease the microbial load around 4.0 log cycles for both squeeze levels. All HHP treatments showed no significant decrease at antioxidant activity, total phenolic content and monomeric anthocyanin pigment concentrations, while there was a significant decrease (p ≤ .05) in thermal-treated samples. Being the highest sugar alcohol in pomegranate juice, mannitol content must be considered for determining the authenticity, and mannitol content increased with squeezing pre...
16 citations
TL;DR: The elastic stiffness tensor cij of synthetic strontianite (SrCO3) was determined by Brillouin spectroscopy at ambient conditions as discussed by the authors, and the best fit values of c11, c12, c13, c22, c23, c33, c44, c55 and c66 were 153(1), 52(1, 38(11), 109.6(8), 43(15), 75(1) and 33.2(5) GPa, respectively.
Abstract: The elastic stiffness tensor cij of synthetic strontianite (SrCO3) was determined by Brillouin spectroscopy at ambient conditions. An inversion procedure based on Christoffel’s equation was used to determine the 9 independent elastic coefficients of orthorhombic strontianite from acoustic velocities measured along 69 different crystallographic directions in 3 randomly oriented crystal platelets. The best fit values of c11, c12, c13, c22, c23, c33, c44, c55 and c66 are 153(1), 52(1), 38(11), 109.6(8), 43(15), 75(1), 28.0(5), 28.6(4) and 33.2(5) GPa, respectively. The linear compressibilities of a-, b- and c-axis at ambient conditions are 3(2), 4(6) and 10(8) 10−3 GPa−1. The adiabatic bulk modulus of strontianite is 64(4) GPa, intermediate between aragonite (CaCO3) and witherite (BaCO3), thus confirming a systematic linear relationship between cation radius and bulk modulus in aragonite-type carbonates. The shear modulus of strontianite has a value of 31(1) GPa, which is about 10% smaller in compari...
13 citations
TL;DR: In this paper, a first-principles density functional theory study on the pressure dependence of the structural parameters, elastic constants and related properties and thermodynamic properties is presented.
Abstract: We report a systematic first-principles density functional theory study on the pressure dependence of the structural parameters, elastic constants and related properties and thermodynamic propertie...
TL;DR: In this article, a systematic investigation on the fluorescent spectra of SrB4O7:Sm2+ was performed in detail at high-temperature up to 623 K and/or high pressure up to 23.2 GPa with different pressure-transmitting media (PTMs), respectively.
Abstract: A systematic investigation on the fluorescent spectra of SrB4O7:Sm2+ was performed in detail at high-temperature up to 623 K and/or high pressure up to 23.2 GPa with different pressure-transmitting media (PTMs), respectively. Combined with experiment data of previous research, the change of the 7D0–5F0 line (0–0 line) full width at half maximum (FWHM) of SrB4O7:Sm2+ under different pressure environments was specifically discussed. The results indicate that the FWHM of 0–0 line is sensitive to the non-hydrostatic pressure environment in 2-propanol, and methanol and ethanol mixture (ME) PTMs at ambient temperature. The first-order and the second-order derivation of the temperature dependence of 0–0 line FWHM at ambient pressure are 1.48(±0.21) × 10−4 nm/K and 9.63(±0.63) × 10−7 nm2/K2 below 623 K. The 0–0 line FWHM is also sensitive to the non-hydrostatic pressure environment in ME at high-temperature and high pressure simultaneous, the non-hydrostatic transition pressures are 9.6 GPa at 323 K, 11.0...
TL;DR: In this article, a series of Raman experiments on the phase transition of calcite at high pressure and high temperature were investigated using a hydrothermal diamond anvil cell and Raman spectroscopy.
Abstract: In our study, a series of Raman experiments on the phase transition of calcite at high pressure and high temperature were investigated using a hydrothermal diamond anvil cell and Raman spectroscopy...
TL;DR: In this paper, the high pressure behavior of gallium phosphide, GaP, has been examined using the synchrotron X-ray diffraction technique in a diamond anvil cell up to 27
Abstract: The high pressure behavior of gallium phosphide, GaP, has been examined using the synchrotron X-ray diffraction technique in a diamond anvil cell up to 27 GPa and 900 K. The transition from a semiconducting to a metallic phase was observed. This transition occurred at 22.2 GPa and room temperature, and a negative dependence of temperature of this transition was found. The transition boundary was determined to be P (GPa) = 22.6 − 0.0014 × T (K).
TL;DR: In this article, the effects of chemical variability on physical properties of single-crystal samples in the diamond-anvil cell by employing a multi-sample approach is investigated. But the results suggest that the multi-sampling approach allows for the quantification of small effects of small chemical variations, such as iron and hydrogen incorporation, on physical property.
Abstract: We present a method to perform improved measurements of the effects of chemical variability on physical properties of single-crystal samples in the diamond-anvil cell by employing a multi-sample approach. By customizing the sizes and shapes of the samples using a focused ion beam machine the simultaneous loading of relatively large crystals into a single sample chamber becomes feasible. To illustrate the potential of this approach, elastic properties of four single crystals of ringwoodite with different chemical compositions have been measured at high pressure. Our results suggest that the multi-sample approach allows for the quantification of small effects of chemical variations, such as iron and hydrogen incorporation, on physical properties. Furthermore, we discuss the possibility of using the multi-sample approach to load several crystals with different crystallographic orientations of the same material into one sample chamber in order to map out the direction dependence of anisotropic physica...
TL;DR: In this article, a diamond anvil cell was designed to detect superconductivity using a superconducting QUantum interference device (QUID) magnetometer in dense hydrides directly synthesized by the reaction of hydrogen with a chemical element.
Abstract: A new miniature diamond anvil cell was specifically designed to detect superconductivity using a SQUID (Superconducting QUantum Interference Device) magnetometer in dense hydrides directly synthesized by the reaction of hydrogen with a chemical element. The cell, made of a CuTi alloy, is fully symmetric with a very low magnetic background allowing the detection of the superconductivity of a sample as small as 3.4 × 104 µm3 without background subtraction. DC measurements or AC measurements in a Magnetic Property Measurement System 3 SQUID magnetometer from Quantum Design could be performed at temperatures as low as 3 K. This high pressure cell is inserted in a modified conventional membrane diamond anvil cell to be driven for hydrogen gas loading and for fine pressure increase before magnetic measurements are performed. To synthetize and structurally characterize the superconducting sample, a 21° optical and 8.6° X-ray acceptance angle allows one to perform laser heating and X-ray diffraction at th...
TL;DR: In this paper, a combined high pressure Ni K-edge x-ray absorption and Raman spectroscopic investigation of β-Ni(OH)2 was presented, which revealed a progressive shrinking of the Ni-O and Ni-Ni bond distances with pressure.
Abstract: We present a combined high pressure Ni K-edge x-ray absorption and Raman spectroscopic investigation of β-Ni(OH)2. Extended x-ray absorption fine structure analysis reveals a progressive shrinking of the Ni–O and Ni–Ni bond distances with pressure. As pressure is increased, Raman data show a continuous hardening of the phonon modes associated with the vibration of Ni–O sublattice, whereas a systematic frequency softening is displayed by the hydroxyl (O–H) symmetric stretching mode. This contrasting behavior implies a gradual development of a lattice instability with pressure in nickel hydroxide. Under pressure hydrogen bonds become increasingly unstable mainly due to the displacement of H atoms around the Ni–O axis inducing a local-lattice instability may explain the structural, Raman and x-ray absorption results.
TL;DR: It has been demonstrated that pasteurized effect on microorganisms of petit-high pressure carbon dioxide (p-HPCD) with long time treatment is similar to the effect of HPCD with short time treatment.
Abstract: It has been demonstrated that pasteurized effect on microorganisms of petit-high pressure carbon dioxide (p-HPCD) with long time treatment is similar to the effect of HPCD with short time treatment. The ‘petit-high pressure’ refers to a pressure of 1.5–13 atm (standard atmosphere). After 0.5 MPa of CO2 at 25°C for 2 h treatment, specific growth rate of yeast cells in the logarithm phase was decreased by 50% approximately. Under this condition, our study analyzed transcriptional responses of Saccharomyces cerevisiae through the functional genomic approach. Transcription of 837 open reading frames (ORFs) was altered relative to cells without treatment and 476 ORFs were induced after p-HPCD treatment. These selected genes were then categorized by function of gene product using the Munich Information Centre for Protein Sequences database. Genes involved in ‘metabolism of the urea cycle’ were found to be significantly induced. This enhanced metabolic process could help to remove redundant HCO3− in cell...
TL;DR: In this article, the authors highlight recent developments to measure the density of amorphous material, mainly silicate glasses made of light elements, to high pressure conditions, and discuss the X-ray absorption method at synchrotron sources as a new opportunity for high pressure experiments on glasses, fluids, and melts.
Abstract: Density and structural changes of matter in their liquid or amorphous form, such as silicates melts, molecular fluids, or glasses, are of extreme importance to model the interior of planetary bodies. However, measuring the evolution of amorphous materials under extreme conditions of pressure and temperature remains challenging mainly because of the sample dimensions and the weak interaction with X-ray probes. This contribution highlights recent developments to measure the density of amorphous material, mainly silicate glasses made of light elements, to high pressure conditions. In particular, the X-ray absorption method at synchrotron sources is discussed as a new opportunity for high pressure experiments on glasses, fluids, and melts. Recent achievements using X-ray Raman scattering spectroscopy to obtain data on the local electronic environment of the main constituents of silicate glasses at high pressure are also presented. Finally, perspectives of these recent developments are discussed as wel...
TL;DR: In this article, the structural stability of niobium carbide has been investigated under high pressure in a diamond anvil cell at room temperature and high pressure (up to 38.0 GPa).
Abstract: We report the combined experimental and theoretical investigations on high pressure structural stability of niobium carbide (NbC). The compressibility of NbC has been measured using angle-dispersive synchrotron X-ray diffraction in a diamond anvil cell (DAC) at room temperature and high pressure (up to 38.0 GPa), complemented with first-principles density-function theory calculations. The results imply that NbC shows bulk modulus of K0 = 281 (6) GPa with a pressure derivative K0′ = 6.2 (1.5) for its strong covalent bonding. In addition, indentation testing on the well-sintered bulk NbC obtained at 5.0 GPa/1400°C yielded a Vickers hardness of 19.2 GPa and fracture toughness of 7.7 MPa m1/2 at applied load of 10 kgf, demonstrating that binderless NbC prepared under high pressure should be a prospective hard material.
TL;DR: The structural properties of pyrochlore Eu2Zr2O7 under high pressure have been studied by using Raman spectroscopy and in situ angle-dispersive X-ray diffraction (ADXRD) as mentioned in this paper.
Abstract: The structural properties of pyrochlore Eu2Zr2O7 under high pressure have been studied by using Raman spectroscopy and in situ angle-dispersive X-ray diffraction (ADXRD). The results of Raman spectra indicate that Eu2Zr2O7 undergoes a reversible structural change around 21.2 GPa. The results of Rietveld refinements from in situ ADXRD data indicate that the ordered pyrochlore structure (Fd-3m) transforms to the defect-cotunnite structure (Pnma) at 26.5 GPa. The phase transition is irreversible and the transformation process is mainly induced by the accumulations of anti-site defects of the cation sublattice and Frenkel defects on the anion sublattice. Besides, the bonds should play a more important role than the bonds in the process of the phase transformation.
TL;DR: In this article, the authors examined the effects of pressure on microstructure and mechanical properties of pure Zr and found that pressure significantly affected refining of Zr microstructures.
Abstract: The present study examined the effects of pressure (range: 1–6 GPa) on microstructure and mechanical properties of pure Zr. Pressure significantly affected refining of Zr microstructure. When 5 GPa pressure was applied, ω-phase was observed in processed specimen, and volume fraction sharply increased to 57.4% for specimen pressurized-quenched at 6 GPa. Benefitting from refinement of acicular-shaped α (α′) plates and the formation of equiaxial ω-phase, the yield strength of the sample quenched from 6 GPa reached ∼616 MPa, which is almost twice as that of coarse-grained Zr.
TL;DR: In this paper, it was shown that diamond anvils made with their [001] axis oriented in line with the principal stress axis of the anvil or at a small angle to it often failed with flat faces having {110} orientations; a cleavage plane is reported in some publications.
Abstract: The extraordinary properties of diamond make it the number-one choice for anvils in high pressure experiments involving anvil cells. In much of the literature on the properties of diamond the only cleavage mentioned is {111}. However, experience has shown that diamond anvils made with their [001] axis oriented in line with the principal stress axis of the anvil or at a small angle to it often failed with flat faces having {110} orientations; a cleavage plane is reported in some publications. Analysis of the anisotropy of strength and Poisson ratio in diamond has shown that such orientations do, indeed, favor initial failure on {110} cleavage planes. This analysis, in conjunction with stereographic projections of the {111} and {110} cleavage planes, suggests that a 27° tilt of the [001] axis with respect to the linear stress axis by rotation around the [100] or [010] axis should provide significantly greater resistance to failure by cleaving.
TL;DR: In this article, the authors investigated the potential of pressure-assisted thermal sterilization (PATS) technology for baby food sterilization and found that the decimal reduction time of Bacillus subtilis in PATS treatment was lower than that of thermal only treatment.
Abstract: Currently baby food is sterilized using retort processing that gives an extended shelf life. However, this type of heat processing leads to reduction of organoleptic and nutrition value. Alternatively, the combination of pressure and heat could be used to achieve sterilization at reduced temperatures. This study investigates the potential of pressure-assisted thermal sterilization (PATS) technology for baby food sterilization. Here, baby food (apple puree), inoculated with Bacillus subtilis spores was treated using PATS at different operating temperatures, pressures and times and was compared with thermal only treatment. The results revealed that the decimal reduction time of B. subtilis in PATS treatment was lower than that of thermal only treatment. At a similar spore inactivation, the retention of ascorbic acid of PATS-treated sample was higher than that of thermally treated sample. The results indicated that PATS could be a potential technology for baby food processing while minimizing quality...
TL;DR: In this paper, a powder mixture of WC-10-wt% Co was sintered at 1500-1900°C under a pressure of 7.7-GPa for 2 and 3 min.
Abstract: This work focused on fracture toughness studies of WC–10 wt% Co hardmetal fabricated through the high pressure/high-temperature technique. A powder mixture of WC–10 wt% Co was sintered at 1500–1900°C under a pressure of 7.7 GPa for 2 and 3 min. Vickers hardness test at two different loads of 15 and 30 kgf was done and fracture toughness of the sintered bodies was measured using the indentation method to obtain the effect of sintering parameters. Structural analyses were also performed via X-ray diffraction to investigate structure-related properties. Full density was achieved for high sintering temperature along with abnormal grain growth that reduced hardness. High hardness was observed ranging from 1200 to 1670 HV and fracture toughness increased with increasing sintering temperature up to the highest value of 17.85 MPa/m1/2.
TL;DR: In this paper, pressure effects on melting temperature and shear modulus of hcp-iron have been studied based on the semi-empirical approach in the Debye model.
Abstract: The pressure effects on melting temperature and shear modulus of hcp-iron have been studied based on the semi-empirical approach in the Debye model. The recent well-established pressure-dependent G...
TL;DR: In this article, a brief review of dynamic compression itself, its application to making metallic fluid H (MFH) and implications of data generated at extreme conditions with dynamic compression for understanding the unusual magnetic fields of Uranus and Neptune, which are made primarily by convection of semiconducting and MFH is compared.
Abstract: Static compression is a well-known method to achieve very high pressures in ‘cold’ (degenerate) condensed matter. Because dynamic compression is adiabatic, it achieves both high pressures and temperatures, which are tunable by choice of pressure-pulse shape. Dynamic compression uses supersonic hydrodynamic variables, which are straight forward to measure, to achieve a wide range of extreme thermodynamic states in degenerate condensed matter. Because dynamic compression developed primarily in national laboratories, it is relatively unknown to a significant portion of the high pressure community. This paper is a brief review of (i) dynamic compression itself, (ii) its application to making metallic fluid H (MFH) and (iii) implications of data generated at extreme conditions with dynamic compression for understanding the unusual magnetic fields of Uranus and Neptune, which are made primarily by convection of semiconducting and MFH. Metallic hydrogen made under dynamic and static compression is compared.
TL;DR: In this article, the effect of high pressure on the microstructure and thermoelectric performance of BiCuSeO oxyselenide was investigated and the maximum figure of merit ZT∼0.4 was obtained for the HPS sample, which is about 3 times higher than the PLS sample.
Abstract: Polycrystalline BiCuSeO oxides are prepared by solid-state reaction followed by pressureless sintering (PLS) and high pressure sintering (HPS) methods. Both the experimental results and the density functional theory calculations indicate that the crystal defect concentrations of BiCuSeO can be reduced under the effect of high pressure. By comparing with the PLS sample, a larger power factor and a lower thermal conductivity can be obtained for the HPS sample. The maximum figure of merit ZT∼0.4 @ 800 K was obtained for the HPS sample, which is about 3 times higher than the PLS sample. These results indicate that the effect of high pressure is beneficial to modifying the microstructure and improving the thermoelectric performance of BiCuSeO oxyselenide.
TL;DR: It is shown that HHP inactivation of all strains tended to be more effective in presence of fat, and the observation in both, surfactant-stabilized and surfACTant-free (O/W)-emulsion, indicates that cell surface hydrophobicity is no intrinsic pressure resistance factor.
Abstract: Inactivation efficiency of high hydrostatic pressure (HHP) processing of food is strongly affected by food matrix composition. We investigated effects of fat on HHP inactivation of spoilage-associated Lactobacillus (L.) plantarum strains using defined oil-in-water (O/W)-emulsion model systems. Since fat-mediated effects on HHP inactivation could be dependent on interactions between lipid phase and microbial cells, three major factors possibly influencing such interactions were considered, that is, cell surface hydrophobicity, presence and type of surfactants, and oil droplet size. Pressure tolerance varied noticeably among L. plantarum strains and was independent of cell surface hydrophobicity. We showed that HHP inactivation of all strains tended to be more effective in presence of fat. The observation in both, surfactant-stabilized and surfactant-free (O/W)-emulsion, indicates that cell surface hydrophobicity is no intrinsic pressure resistance factor. In contrast to the presence of fat per se, ...
TL;DR: In this article, an X-ray diffraction study using synchrotron radiation was conducted to determine the pressure and volume of natural goethite (α-FeOOH) using the third-order Birch-Murnaghan EoS.
Abstract: The pressure–volume–temperature (P–V–T) equation of state (EoS) of natural goethite (α-FeOOH) has been determined by an X-ray diffraction study using synchrotron radiation. Fitting the volume data to the third-order Birch–Murnaghan EoS yielded an isothermal bulk modulus, B0 of 85.9(15) GPa, and a pressure derivative of the bulk modulus, B′, of 12.6(8). The temperature derivative of the bulk modulus, (∂B/∂T)P, was –0.022(9) GPa K−1. The thermal expansion coefficient α0 was determined to be 4.0(5) × 10−5 K−1.