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Abstract: The crystal structure and bonding environment of K2Ca(CO3)2 bütschliite were probed under isothermal compression via Raman spectroscopy to 95 GPa and single crystal and powder X-ray diffraction to 12 and 68 GPa, respectively. A second order Birch-Murnaghan equation of state fit to the X-ray data yields a bulk modulus, $${K}_{0}=46.9$$ K 0 = 46.9 GPa with an imposed value of $${K}_{0}^{\prime}= 4$$ K 0 ′ = 4 for the ambient pressure phase. Compression of bütschliite is highly anisotropic, with contraction along the c-axis accounting for most of the volume change. Bütschliite undergoes a phase transition to a monoclinic C2/m structure at around 6 GPa, mirroring polymorphism within isostructural borates. A fit to the compression data of the monoclinic phase yields $${V}_{0}=322.2$$ V 0 = 322.2  Å3$$,$$ , $${K}_{0}=24.8$$ K 0 = 24.8 GPa and $${K}_{0}^{\prime}=4.0$$ K 0 ′ = 4.0 using a third order fit; the ability to access different compression mechanisms gives rise to a more compressible material than the low-pressure phase. In particular, compression of the C2/m phase involves interlayer displacement and twisting of the [CO3] units, and an increase in coordination number of the K+ ion. Three more phase transitions, at ~ 28, 34, and 37 GPa occur based on the Raman spectra and powder diffraction data: these give rise to new [CO3] bonding environments within the structure.

Solid solutions Nd 2 MnMn(Mn 4− x Sb x)O 12 , belonging to the A-site columnar-ordered quadruple perovskite subfamily A 2 A′A″B 4 O 12 and prepared by a high-pressure, high-temperature method at about 6 GPa and about 1700 K, were investigated in a compositional range of 0.2 ≤ x ≤ 2.0. Crystal structures were studied using synchrotron powder X-ray diffraction. Two regions with different cation orders in the B sublattice were found: a narrow region of 0.8 ≤ x ≤ 1.0 had a B-site disordered structure with space group P 4 2 / nmc (No. 137), and a wider region of 1.6 ≤ x ≤ 2.0 had a B-site rock-salt-ordered structure with space group P 4 2 / n (No. 86). Small anti-site disorder of Nd and Mn was detected among the A, A′, and A″ sites. In the B-site rock-salt-ordered structures, one B site was solely occupied by Mn, the second B′ site had a mixture of Sb and Mn (for x < 2). The samples showed complex magnetic behavior with two ferrimagnetic transitions. T C1 monotonically increased (from 66 K to 75 K) and T C2 was almost constant (about 6–7 K) for 0.8 ≤ x ≤ 1.0. T C1 monotonically decreased (from 77 K to 63 K) and T C2 monotonically increased (from 19 K to 39 K) for 1.6 ≤ x ≤ 2.0. There was evidence for the third magnetic transition in the 1.7 ≤ x ≤ 2.0 samples, and T C3 increased from 13 K to 20 K with increasing x. [ABSTRACT FROM AUTHOR]

Developing strategies to systematically increase the critical current, the threshold current below which the superconductivity exists, is an important goal of materials science. Here, the concept of quantum phase transition is employed to enhance the critical current of a kagome superconductor CsV3Sb5, which exhibits a charge density wave (CDW) and superconductivity that are both affected by hydrostatic pressure. As the CDW phase is rapidly suppressed under pressure, a large enhancement in the self‐field critical current (Ic, sf) is recorded. The observation of a peak‐like enhancement of Ic, sf at the zero‐temperature limit (Ic, sf(0)) centered at p* ≈ 20 kbar, the same pressure where the CDW phase transition vanishes, further provides strong evidence of a zero‐temperature quantum anomaly in this class of pressure‐tuned superconductor. Such a peak in Ic, sf(0) resembles the findings in other well‐established quantum‐critical superconductors, hinting at the presence of enhanced quantum fluctuations associated with the CDW phase in CsV3Sb5. [ABSTRACT FROM AUTHOR]

Developing strategies to systematically increase the critical current, the threshold current below which the superconductivity exists, is an important goal of materials science. Here, the concept of quantum phase transition is employed to enhance the critical current of a kagome superconductor CsV3Sb5, which exhibits a charge density wave (CDW) and superconductivity that are both affected by hydrostatic pressure. As the CDW phase is rapidly suppressed under pressure, a large enhancement in the self‐field critical current (Ic, sf) is recorded. The observation of a peak‐like enhancement of Ic, sf at the zero‐temperature limit (Ic, sf(0)) centered at p* ≈ 20 kbar, the same pressure where the CDW phase transition vanishes, further provides strong evidence of a zero‐temperature quantum anomaly in this class of pressure‐tuned superconductor. Such a peak in Ic, sf(0) resembles the findings in other well‐established quantum‐critical superconductors, hinting at the presence of enhanced quantum fluctuations associated with the CDW phase in CsV3Sb5. [ABSTRACT FROM AUTHOR]

The increasing consumer demand for minimally processed and ready-to-cook food products has elevated the significance of fresh-cut potatoes, which offer health benefits, high sensory properties, and convenience. However, extending the shelf life of fresh-cut potatoes while preserving their organoleptic qualities remains a significant challenge. This review examines the effectiveness of emerging non-thermal technologies, such as osmotic dehydration (OD), high-pressure processing (HPP), pulsed electric field (PEF), and ohmic heating (OH), in processing fresh-cut potatoes. Among these, HPP and PEF have shown particular promise in extending shelf life and preserving sensory attributes, while OD and OH present advantages in maintaining nutritional quality. However, challenges such as high energy consumption, equipment costs, and industrial scalability limit their broader application. The use of natural preservatives and edible coatings is also explored as a means to enhance product quality and address the demand for clean-label foods. Further research is needed to optimize these technologies for large-scale production, reduce energy usage, and explore combined approaches for improved shelf life extension. This comprehensive review provides a critical analysis of the operational parameters of these technologies and their impact on the quality and shelf life of fresh-cut potatoes, identifying current research gaps and proposing directions for future studies. [ABSTRACT FROM AUTHOR]

This study aims to evaluate homogenization techniques and conditions for producing stable, small droplet‐size water‐in‐oil (W/O) emulsions intended for incorporation into casein hydrolysate–loaded double emulsions. Three commonly used homogenization methods; rotor–stator, ultrasonic, and high‐pressure homogenization were individually optimized utilizing response surface methodology. Instances of over‐processing were observed, particularly with the rotor–stator and ultrasonic homogenizers under specific conditions. Nevertheless, optimal conditions were identified for each technique: 530 s at 17,800 rpm agitation speed for the rotor–stator homogenizer, 139 s at 39% amplitude for the ultrasonic homogenizer, and 520 s at 1475 bar for the high‐pressure homogenizer. Subsequently, the W/O emulsions produced under optimal conditions and their respective W1/O/W2 double emulsions were compared. The rotor–stator and high‐pressure homogenized W/O emulsions exhibited comparable narrow droplet‐size distributions, as indicated by similar Span values. However, high‐pressure homogenization failed to sufficiently minimize droplet size. Ultrasonic homogenization resulted in droplets at the 1‐μm scale but yielded more polydisperse droplet‐size distribution. According to TOPSIS analysis, an emulsion with a viscosity of 93.1 cP (centiPoise), a stability index of 93.8%, a D(90) of 0.67 μm (0th day), and a D(90) of 0.75 μm (30th day) produced using a rotor–stator was selected. Additionally, double emulsions containing primary emulsions prepared with the rotor–stator method demonstrated higher viscosity, narrower droplet‐size distribution, and lower creaming compared to other samples. This investigation sheds light on the influence of homogenization techniques on emulsion properties, providing valuable insights for optimizing double emulsion formulations. [ABSTRACT FROM AUTHOR]

In situ X-ray diffraction and Raman spectroscopy of a synthetic whitlockite, Ca9Mg(PO3OH) (PO4)6, have been conducted at high pressures or high temperatures. The results show that whitlockite is stable up to ~15 GPa at ambient temperature and undergoes a thermally induced dehydrogenation to merrillite above 973 K at ambient pressure. The obtained pressure-volume data were fitted using a third-order Birch-Murnaghan equation of state, yielding an isothermal bulk modulus of K0 = 79(4) GPa with a pressure derivative of K 0 ′ = 4.3(6). When K 0 ′ was fixed at 4, the refined isothermal bulk modulus was 81(1) GPa. The volumetric thermal expansion coefficient (αV) is 4.05(8) × 10-5 K−1, and the axial thermal expansion coefficients (αa and αc) are 1.07(5) × 10−5 K−1 and 1.91(6) × 10−5 K−1. Both compressibility and thermal expansion show an axial anisotropy. The effects of pressure and temperature on the Raman spectra of whitlockite have been quantitatively analyzed. The isothermal and isobaric mode Grüneisen parameters and the intrinsic anharmonic mode parameters of whitlockite were derived. Some amounts of OH−-bearing whitlockite may be preserved in meteorites if whitlockite undergoes a low-temperature process. [ABSTRACT FROM AUTHOR]

Elucidating the phase diagram of solid hydrogen is a key objective in condensed matter physics. Several decades ago, it was proposed that at low temperatures and high pressures, solid hydrogen would be a metal with a high superconducting transition temperature. This transition to a metallic state can happen through the closing of the energy gap in the molecular solid or through a transition to an atomic solid. Recent experiments have managed to reach pressures in the range of 400-500 GPa, providing valuable insights. There is strong evidence suggesting that metallization via either of these mechanisms occurs within this pressure range. Computational and experimental studies have identified multiple promising crystal phases, but the limited accuracy of calculations and the limited capabilities of experiments prevent us from determining unequivocally the observed phase or phases. Therefore, it is crucial to investigate the superconducting properties of all the candidate phases. Recently, we reported the superconducting properties of theC2/c-24,Cmca-12,Cmca-4 andI41/amd-2 phases, including anharmonic effects. Here, we report the effects of anisotropy on superconducting properties using Eliashberg theory. Then, we investigate the superconducting properties of deuterium and estimate the size of the isotope effect for each phase. We find that the isotope effect on superconductivity is diminished by anharmonicity in theC2/c-24 andCmca-12 phases and enlarged in theCmca-4 andI41/amd-2 phases. Our anharmonic calculations of theC2/c-24 phase of deuterium agree closely with the most recent experiment by Loubeyreet al(2022Phys. Rev. Lett.29035501), indicating that theC2/c-24 phase remains the leading candidate in this pressure range, and has a strong anharmonic character. These characteristics can serve to distinguish among crystal phases in experiment. Furthermore, expanding our understanding of superconductivity in pure hydrogen holds significance in the study of high-Tchydrides.

This study developed a fibre-optic laser Doppler velocimetry sensor for use in opaque, high-temperature, and high-pressure fluid flows by inserting the fibre perpendicular to the main flow. The tip of the optical fibre was obliquely polished and chemically etched using a buffered hydrofluoric acid solution, and a reflective mirror was deposited on the surface of the oblique fibre tip. Based on the results of the verification test using the rotating annular open channel, the fabrication conditions of the fibre tip were optimized for measuring the lubricating oil flow. The flow velocity profiles in the engine's oil flow of the lubrication system during engine bench testing were measured. These velocity profiles were influenced by variations in the measurement position, oil temperature, and engine speed. The measurement accuracy of this sensor was compared with the volumetric flow rate obtained by cross-sectional area integration of the flow velocity profile, as measured using a Coriolis flowmeter, and the difference was within 1%. By combining computational simulation for flow and optical attenuation and particle scattering in light transmission through a working fluid, this fibre-optic sensor achieved a measurement volume of 200 microns in length and 200 microns in width at a distance of 900–1000 microns from the sensor. [ABSTRACT FROM AUTHOR]

Alternatives to the conventional thermal processing (TT) of food are an area of research that has grown tremendously in recent decades. The impact of these alternative techniques on the sensory profile of fruit juices has been discussed in the literature but only in a fragmented manner. This review takes a macroscopic approach to discuss the influence of emerging thermal and non-thermal techniques currently used by industries on a commercial scale, like high-pressure processing (HPP), ohmic heating (OH), and pulse electric field processing (PEF), on certain sensory characteristics of fruit juices and beverages. A sensory impression of a product is a result of a complex mixture of several compounds. The sensory profile varies with the type of processing technique due to differences in intensities and the inactivation mechanism for enzymes. Heat plays a role in the generation of flavor and odor-active compounds; hence, a different sensory profile is expected with alternative techniques that operate at ambient temperatures (HPP and PEF) or have short treatment time due to rapid heating (OH). HPP, OH, and PEF positively influence the retention of compounds that contribute to a fresh-like sensory experience. However, enzyme inactivation is often challenging with alternative techniques resulting in higher residual activity, affecting sensory quality during storage. Nevertheless, there is evidence in the literature of products with stable sensory properties during storage after processing with alternative techniques. Additionally, some residual enzyme activity may play a role in flavor enhancement during storage, i.e., the release of aglycones from glycoconjugates by pectolytic enzymes. Multiple factors like fruits' cultivar, way of cultivation, external growth conditions, andmaturity stage at the time of harvest influence its sensory quality and, subsequently, the products derived from them. The review concludes with the impression that there is extensive literature on the effects of HPP on the sensory properties of fruit juices. However, the research is limited in discussing the influence of OH and PEF. Additionally, it is difficult to make a fair and systematic comparison among the different preservation technologies because of the lack of standardization and comprehensive sensory evaluation in the studies in the literature. [ABSTRACT FROM AUTHOR]

Abstract Developing strategies to systematically increase the critical current, the threshold current below which the superconductivity exists, is an important goal of materials science. Here, the concept of quantum phase transition is employed to enhance the critical current of a kagome superconductor CsV3Sb5, which exhibits a charge density wave (CDW) and superconductivity that are both affected by hydrostatic pressure. As the CDW phase is rapidly suppressed under pressure, a large enhancement in the self‐field critical current (Ic, sf) is recorded. The observation of a peak‐like enhancement of Ic, sf at the zero‐temperature limit (Ic, sf(0)) centered at p* ≈ 20 kbar, the same pressure where the CDW phase transition vanishes, further provides strong evidence of a zero‐temperature quantum anomaly in this class of pressure‐tuned superconductor. Such a peak in Ic, sf(0) resembles the findings in other well‐established quantum‐critical superconductors, hinting at the presence of enhanced quantum fluctuations associated with the CDW phase in CsV3Sb5.

High-pressure processing (HPP) has been employed in the food and pharmaceutical industries for multiple applications, such as microbial inactivation, shelf life extension, homogenizing/stabilizing emulsions, suspensions, gels, and other colloidal systems, cold extraction of meat in crustaceans, the opening of mollusks, etc. However, high pressure is known to affect the stability and the quality of barosensitive (i.e., sensitivity because of the level of pressure) components of the bioproducts, such as proteins. In general, Le Chatelier's principle dictates the fate of high molecular weight polymeric compounds like proteins under high pressure, suggesting a tendency to degrade into simpler monomers. From a structural analysis point of view, this generally results in increased tendencies for the protein to denature from its native state and possibly affect its ability to renature. Protein crystallization is also affected favorably or unfavorably by pressure, depending on the effect of pressure on nucleation and crystal growth steps for the particular type of protein. Protein refolding is another effect whose kinetics can be optimized by pressure. This work discusses the mechanisms of the impact of pressure on protein structure, crystallization refolding, and unfolding, with examples of the application of these processes in recent literature.

Physical properties of mantle minerals are essential for comprehensive geodynamic modeling. High-pressure experiments allow measurements of physical properties but fundamental insights into their evolution with pressure are often experimentally inaccessible. Here we report the first in situ experimental determination of the optical refractive index, its wavelength-dispersion, and optical absorption coefficient of ferropericlase up to ~140 GPa at room temperature. All these properties change gradually in dominantly high-spin (below ~50 GPa) and low-spin (above ~80 GPa) ferropericlase. However, in the mixed-spin state (i.e., significant presence of both high- and low-spin iron), the index dispersion and the absorption coefficient decrease by a factor of three and ~30%, respectively. These anomalies suggest that charge transport by small polaron is reduced in mixed-spin ferropericlase, providing fundamental insights into the factor-of-three lower electrical conductivity of ferropericlase at ~50–70 GPa. [ABSTRACT FROM AUTHOR]

Safety and reliability are the major challenges to face for the development and acceptance of hydrogen technology. It is therefore crucial to deeply study material compatibility, in particular for tribological components that are directly in contact with hydrogen. Some of the most critical parts are sealing materials that need increased safety requirements. In this study, the fretting behavior of several elastomer materials were evaluated against 316L stainless steel in an air and hydrogen environment up to 10 MPa. Several grades of cross-linked hydrogenated acrylonitrile butadiene (HNBR), acrylonitrile butadiene (NBR) and ethylene propylene diene monomer rubbers (EPDM) were investigated. Furthermore, aging experiments were conducted for 7 days under static conditions in 100 MPa of hydrogen followed by rapid gas decompression. Fretting tests revealed that the wear of these compounds is significantly affected by the hydrogen environment compared to air, especially with NBR grades. After the aging experiment, the friction response of the HNBR grades is characterized by increased adhesion due to elastic deformation, leading to partial slip. [ABSTRACT FROM AUTHOR]

H2S and CO2 are considered two main impurities of natural gas and biogas. These impurities must be removed in order to achieve economic and environmental restrictions. Adsorption is a promising technology studied to achieve this goal. Among alternative adsorbents studied to capture H2S and CO2, porous aromatic frameworks (PAFs) had shown potential application because of suitable selectivity and remarkable adsorption capacity. However, H2S and CO2 adsorption/desorption data on PAF-30 are still scarce in literature. Thus, in this work, H2S (up to 2.5 bar) and CO2 and CH4 (up to 50 bar) adsorption/desorption isotherms on PAF-30 were determined at 293, 303 and 313 K for the first time in literature. PAF-30 was synthesized and characterized by XRD, FTIR, 13C-NMR, Ar and CO2 physisorption, SEM, TEM, TGA and DSC analyzes. Then, adsorption isotherms were determined gravimetrically. Experimental data were modelled with Jensen-Seaton equation. The results indicated that PAF-30 presents adsorption capacities in the order H2S > CO2 > CH4. Adsorption/desorption branches do not match for systems studied, due to a hysteresis effect. Adsorption capacity decreases with temperature, indicating that physisorption is the main phenomenon observed. Experimental data were represented by Jensen-Seaton model. Thermodynamic analysis showed that all systems are exothermic and spontaneous. Working capacities obtained indicate that temperature reduces the performance for gas purification and that H2S systems are affected by hysteresis loop. Moreover, cyclic adsorption results show that PAF-30 has potential to be applied and further studied in PSA simulations for H2S and CO2 capture under high-pressure conditions. [ABSTRACT FROM AUTHOR]

During their formation, terrestrial planets underwent a magma ocean phase during which their metallic cores segregated from their silicate mantles and their early atmospheres formed. These planetary formation processes resulted in a redistribution of the abundances of highly volatile elements (HVEs, such as H, C, N, and S) between the planets' metallic cores, silicate mantles, and atmospheres. This review presents the numerous experimental techniques used to simulate the conditions and identify the parameters that influenced the behavior of HVEs during planetary formation. We also review the analytical techniques used to characterize the different types of experimental samples and quantify the distribution of HVEs between metallic and silicate phases, as well as their solubilities in silicate glasses. This exhaustive review targets students and young researchers beginning their work on the subject, or, more generally, scientists seeking a better understanding of this field of research. [ABSTRACT FROM AUTHOR]

The increasing consumer demand for minimally processed and ready-to-cook food products has elevated the significance of fresh-cut potatoes, which offer health benefits, high sensory properties, and convenience. However, extending the shelf life of fresh-cut potatoes while preserving their organoleptic qualities remains a significant challenge. This review examines the effectiveness of emerging non-thermal technologies, such as osmotic dehydration (OD), high-pressure processing (HPP), pulsed electric field (PEF), and ohmic heating (OH), in processing fresh-cut potatoes. Among these, HPP and PEF have shown particular promise in extending shelf life and preserving sensory attributes, while OD and OH present advantages in maintaining nutritional quality. However, challenges such as high energy consumption, equipment costs, and industrial scalability limit their broader application. The use of natural preservatives and edible coatings is also explored as a means to enhance product quality and address the demand for clean-label foods. Further research is needed to optimize these technologies for large-scale production, reduce energy usage, and explore combined approaches for improved shelf life extension. This comprehensive review provides a critical analysis of the operational parameters of these technologies and their impact on the quality and shelf life of fresh-cut potatoes, identifying current research gaps and proposing directions for future studies.

We report a joint high-pressure experimental and theoretical study of the structural, vibrational, and photoluminescent properties of pure and Eu3+-doped cubic Y2O3 nanoparticles with two very different average particle sizes. We compare the results of synchrotron X-ray diffraction, Raman scattering, and photoluminescence measurements in nanoparticles with ab initio density-functional simulations in bulk material with the aim to understand the influence of the average particle size on the properties of pure and doped Y2O3 nanoparticles under compression. We observe that the high-pressure phase behavior of Y2O3 nanoparticles depends on the average particle size, but in a different way to that previously reported. Nanoparticles with an average particle size of ~37 nm show the same pressure-induced phase transition sequence on upstroke and downstroke as the bulk sample; however, nanoparticles with an average particle size of ~6 nm undergo an irreversible pressure-induced amorphization above 16 GPa that is completed above 24 GPa. On downstroke, 6 nm nanoparticles likely consist of an amorphous phase. [ABSTRACT FROM AUTHOR]

Background: The safety of milk is considered as a significant public health consideration and has been a key concern for consumers worldwide. The concentrations of cyromazine and its metabolic product, melamine, and their dietary risk assessment are investigated in this study. Methods: A total of 182 milk samples containing 15 brands were sampled between June and December 2022 from major and retail markets in Nigeria. After a solid-phase extraction procedure, the concentrations of the two compounds were determined using High- Performance Liquid Chromatography coupled with a Diode-Array Detector. Solid-phase extraction was utilized to extract local and imported evaporated and infant milk with CCl3COOH and CH3CN, followed by clean-up with NH4OH in MeOH. The extracts were analyzed with Agilent High-Performance Liquid Chromatography, including a Zorbax Eclipse+C18 column. Results: For both melamine and cyromazine, the Limits of Detection and Limits of Quantification were 1.29-1.48 and 3.94-4.50 µg/kg, respectively. The precision (Relative Standard Deviation<1), recovery (99.5-102.5%), and regression (r²=0.989) were all excellent. Melamine concentration ranged between 57.6±18.9 and 930.3±379.9 µg/kg among the samples, and cyromazine was 57.2±12.3 and 670.9±87.8 µg/kg. Brand 2, imported from Holland, had the highest detection frequency for the two analytes. Disturbing levels of melamine were detected in Brand 2, particularly that 75 and 95% of the samples had melamine above the acceptable Maximum Residue Limit. However, the estimated daily exposure to the two additives was below the allowed daily intake values, and the Hazard Index (HI) in the different milk samples ranged from 0.02 to 1.22, with one sample having HI>1. Conclusion: The exposure risk of melamine and cyromazine among the general population is acceptable, and smaller HI values demonstrated no significant potential risk for the Nigerian population according to the recommended guidelines. Regulatory agencies are encouraged to step up their surveillance activities to forestall the inclusion of prohibited additives in local and imported milk to protect public health. [ABSTRACT FROM AUTHOR]

The effect of thermal pasteurization (TP, 62.5 °C/30 min—conditions similar to those used in milk banks/hospitals, known as Holder pasteurization) and high-pressure pasteurization (HPP: 400–625 MPa/2.5–30 min) was studied on immunoglobulin (IgG, IgM and IgA) content, lysozyme activity and microbial load of donkey colostrum (in this case, after 40 days at 4 °C). IgG level remained unchanged with HPP at 400 MPa, increased up to 4-fold at 625 MPa/10 min and decreased 90% with TP, while IgM decreased progressively with pressure treatment intensity increment to below the detection limit at 625 MPa and decreased 20% with TP. IgA decreased to below the detection limit after TP and all HPP treatments. Lysozyme activity presented overall a higher decrease after TP (37%) compared to HPP (decreasing from 20% at 400 MPa to about 40% at 600 MPa/10 and 30 min). Furthermore, both total aerobic mesophiles and Enterobacteriaceae remained below detection limits after 40 days of refrigerated storage for both TP and HPP. So, HPP can be considered a potential alternative to the conventional TP to preserve donkey colostrum, with overall equal to better retention, particularly for IgG and lysozyme activity. As far as the authors are aware, this is the first study evaluating the effects of HPP on donkey colostrum, and research in this field should be pursued. [ABSTRACT FROM AUTHOR]

Topological superconductors have drawn significant interest from the scientific community due to the accompanying Majorana fermions. Here, the discovery of electronic structure and superconductivity (SC) in high‐entropy ceramics Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2Cx (x = 1 and 0.8) combined with experiments and first‐principles calculations is reported. The Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2Cx high‐entropy ceramics show bulk type‐II SC with Tc ≈ 4.00 K (x = 1) and 2.65 K (x = 0.8), respectively. The specific heat jump (∆C/γTc) is equal to 1.45 (x = 1) and 1.52 (x = 0.8), close to the expected value of 1.43 for the BCS superconductor in the weak coupling limit. The high‐pressure resistance measurements show a robust SC against high physical pressure in Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2C, with a slight Tc variation of 0.3 K within 82.5 GPa. Furthermore, the first‐principles calculations indicate that the Dirac‐like point exists in the electronic band structures of Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2C, which is potentially a topological superconductor. The Dirac‐like point is mainly contributed by the d orbitals of transition metals M and the p orbitals of C. The high‐entropy ceramics provide an excellent platform for the fabrication of novel quantum devices, and the study may spark significant future physics investigations in this intriguing material. [ABSTRACT FROM AUTHOR]

Abstract Layered SnAs‐based Zintl compounds exhibit a distinctive electronic structure, igniting extensive research efforts in areas of superconductivity, topological insulators, and quantum magnetism. In this paper, the crystal structures and electronic properties of the Zintl compound SrSn2As2 upon compression are systematically investigated. Pressure‐induced superconductivity is observed in SrSn2As2 with a nonmonotonic evolution of superconducting transition temperature Tc. Theoretical calculations together with high‐pressure synchrotron X‐ray diffraction and Raman spectroscopy have identified that SrSn2As2 undergoes a structural transformation from a rhombohedral R3¯m phase to the monoclinic C2/m phase. Beyond 28.3 GPa, Tc is suppressed due to a reduction of the density of state (DOS) at the Fermi level. The discovery of pressure‐induced superconductivity, accompanied by structural transitions in SrSn2As2, greatly expands the physical properties of layered SnAs‐based compounds and provides new ground states upon compression.

In this work, we report evidence of pressure-induced changes in the crystal structure of Sr(IO3)2HIO3 connected to changes the coordination of the iodine atom and the of the configuration of HIO3 and IO3 units. The changes favor iodine hypercoordination and happen in two steps on sample compression. Firstly, at 2.5 GPa, [HIO3]·[IO3] complexes are formed, and secondly, at 4.5 GPa, these complexes form dimers of [HIO3]·[IO3]·[IO3]·[HIO3]. The evidence is obtained from a combined experimental and theoretical study performed up to 20 GPa. Synchrotron powder X-ray diffraction, Raman spectroscopy, and optical-absorption experiments have been complemented with density-functional theory calculations, including the study of the topology of the electron density. The changes observed in the crystal structure are related to the transformation of secondary (halogen) bonds into electron-deficient multicenter bonds. The paper also discusses the effect of pressure on the compressibility of the Sr(IO3)2HIO3 crystal structure, its phonons, the electronic band gap, and the refractive index. Sr(IO3)2HIO3 was found to be highly compressible with an anisotropic compressibility. The softening of the internal I–O vibrations of IO3 units was also observed, together with a decrease of the band-gap energy (from 4.1 eV at 0 GPa to 3.7 eV at 20 GPa), a band-gap crossing, and a change in the topology of the band structure, with Sr(IO3)2HIO3 transforming from a direct gap semiconductor at 0 GPa to an indirect gap semiconductor beyond 6 GPa.

A theoretical model of the equation of state based on Eulerian finite theory for high pressure has recently been reported by Singh et al. The adopted model successfully predicted the elastic properties of geophysical minerals and prototype solids and the results were also found favourable with experimental data. We have derived the expression for pressure dependence elastic moduli using the proposed model of the equation of state. In this study, the elastic constants of two hcp-transition metals ∼ Co and Re as function of pressure are computed using these formulated expressions. The obtained high-pressure elastic constants are found to be well consistent with the previous theoretical results and show a good agreement with the experimental results. As a result, the present study may play a vital role in geophysical applications.

High-temperature and high-pressure experiments were conducted on columbite-type ZnNb2O6, reaching temperatures up to 873 K at ambient pressure and pressures up to 30 GPa at ambient temperature, respectively. Through systematic analysis employing synchrotron powder X-ray diffraction and Raman spectroscopy, we examined the crystal structure and phonon behavior. Within the specified temperature range, the orthorhombic phase of ZnNb2O6 (space group: Pbcn) demonstrated notable phase stability, with a thermal expansion coefficient similar to that of isomorphic compounds. Notably, a reversible phase transition was observed under compression at 10 GPa, with diffraction experiments indicating a shift to a monoclinic structure (space group P2/a), which remained stable up to 30 GPa. Changes in Raman modes, lattice parameters, and the unit-cell volume were monitored. A significant 2.5 % discontinuity in the unit-cell volume at the phase transition pressure from orthorhombic to monoclinic suggests a first-order phase transition. The bulk moduli of the orthorhombic and monoclinic phases were estimated as 165(7) GPa and 230(9) GPa, respectively- We also found that both phases exhibit an anisotropic response to pressure. Furthermore, first-principles calculations support consistently with experimental observations.

As the simplest element in nature, unraveling the phase diagram of hydrogen is a primary task for condensed matter physics. As conjectured many decades ago, in the low-temperature and high-pressure part of the phase diagram, solid hydrogen is expected to become metallic with a high superconducting transition temperature. The metallization may occur via band gap closure in the molecular solid or via a transition to the atomic solid. Recently, a few experimental studies pushed the achievable pressures into the 400-500 GPa range. There are strong indications that at some pressure in this range metallization via either of these mechanisms occurs, although there are disagreements between experimental reports. Furthermore, there are multiple good candidate crystal phases that have emerged from recent computational and experimental studies which may be realized in upcoming experiments. Therefore, it is crucial to determine the superconducting properties of these candidate phases. In a recent study, we reported the superconducting properties of theC2/c-24 phase, which we believe to be a strong candidate for metallization via band gap closure (Doganet al2022Phys. Rev. B105L020509). Here, we report the superconducting properties of theCmca-12,Cmca-4 andI41/amd-2 phases including the anharmonic effects using a Wannier function-based densek-point andq-point sampling. We find that theCmca-12 phase has a superconducting transition temperature that rises from 86 K at 400 GPa to 212 K at 500 GPa, whereas theCmca-4 andI41/amd-2 phases show a less pressure-dependent behavior with theirTcin the 74-94 K and 307-343 K ranges, respectively. These properties can be used to distinguish between crystal phases in future experiments. Understanding superconductivity in pure hydrogen is also important in the study of high-Tchydrides.

This study developed a fibre-optic laser Doppler velocimetry sensor for use in opaque, high-temperature, and high-pressure fluid flows by inserting the fibre perpendicular to the main flow. The tip of the optical fibre was obliquely polished and chemically etched using a buffered hydrofluoric acid solution, and a reflective mirror was deposited on the surface of the oblique fibre tip. Based on the results of the verification test using the rotating annular open channel, the fabrication conditions of the fibre tip were optimized for measuring the lubricating oil flow. The flow velocity profiles in the engine’s oil flow of the lubrication system during engine bench testing were measured. These velocity profiles were influenced by variations in the measurement position, oil temperature, and engine speed. The measurement accuracy of this sensor was compared with the volumetric flow rate obtained by cross-sectional area integration of the flow velocity profile, as measured using a Coriolis flowmeter, and the difference was within 1%. By combining computational simulation for flow and optical attenuation and particle scattering in light transmission through a working fluid, this fibre-optic sensor achieved a measurement volume of 200 microns in length and 200 microns in width at a distance of 900–1000 microns from the sensor.

Abstract Topological superconductors have drawn significant interest from the scientific community due to the accompanying Majorana fermions. Here, the discovery of electronic structure and superconductivity (SC) in high‐entropy ceramics Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2Cx (x = 1 and 0.8) combined with experiments and first‐principles calculations is reported. The Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2Cx high‐entropy ceramics show bulk type‐II SC with Tc ≈ 4.00 K (x = 1) and 2.65 K (x = 0.8), respectively. The specific heat jump (∆C/γTc) is equal to 1.45 (x = 1) and 1.52 (x = 0.8), close to the expected value of 1.43 for the BCS superconductor in the weak coupling limit. The high‐pressure resistance measurements show a robust SC against high physical pressure in Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2C, with a slight Tc variation of 0.3 K within 82.5 GPa. Furthermore, the first‐principles calculations indicate that the Dirac‐like point exists in the electronic band structures of Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2C, which is potentially a topological superconductor. The Dirac‐like point is mainly contributed by the d orbitals of transition metals M and the p orbitals of C. The high‐entropy ceramics provide an excellent platform for the fabrication of novel quantum devices, and the study may spark significant future physics investigations in this intriguing material.

Using first-principles calculations and crystal structure search methods, we found that many covalently bonded molecules such as H2, N2, CO2, NH3, H2O and CH4 may react with NaCl, a prototype ionic solid, and form stable compounds under pressure while retaining their molecular structure. These molecules, despite whether they are homonuclear or heteronuclear, polar or non-polar, small or large, do not show strong chemical interactions with surrounding Na and Cl ions. In contrast, the most stable molecule among all examples, N2, is found to transform into cyclo-N5− anions while reacting with NaCl under high pressures. It provides a new route to synthesize pentazolates, which are promising green energy materials with high energy density. Our work demonstrates a unique and universal hybridization propensity of covalently bonded molecules and solid compounds under pressure. This surprising miscibility suggests possible mixing regions between the molecular and rock layers in the interiors of large planets. [ABSTRACT FROM AUTHOR]

Nitrogen is the most abundant element in the Earth's atmosphere, yet its geochemical behavior and distribution among the various reservoirs (atmosphere, crust, mantle, and core) remain poorly understood. Although estimates of N and C fluxes in the mantle vary, there is a consensus regarding the disparity between input and output, leading to an increase in N and C contents in the mantle. The low solubility of N in mantle minerals raises questions about possible N or C storage in the mantle. Evidence suggests that Fe–N–C phases, such as Fe3C, Fe7C3, ε-Fe3N, metals, and non-stoichiometric carbonitrides, may be accessory phases at mantle pressure and temperature conditions, and thus potential hosts of C and N in the deep mantle. To investigate the phase relations and melting behavior in the (Fe,Ni)–N–C system, 19 experiments were conducted with varying starting compositions at 10 GPa and 1000–1400 °C. The results indicate that carbides, nitrides, carbonitrides, nitrocarbides, Fe(Ni)-metal, Fe-oxides, and diamond are stable at deep upper mantle pressure conditions. However, the compositions of naturally occurring nitrocarbides with high C and N contents, as found in diamond inclusions, could not be reproduced in the experiments. The significant incorporation of Ni in the experimental phases, which is also not observed in natural carbonitrides and nitrocarbides, suggests their formation in Ni-poor regimes. The solidus temperatures of the N- and C-rich systems are well below the adiabatic temperatures of the surrounding mantle. Therefore, it is hypothesized that cold regions in subduction zones, such as within or at the edge of a C- and N-rich subducted plate, are the likely formation environment for solid Fe–C–N phases. [ABSTRACT FROM AUTHOR]

Currently, there is no well-established framework for studying development patterns in high-pressure, low-permeability reservoirs. The key factors influencing development effect typically include the reservoir properties, well pattern, well spacing, and the rate of oil production. Reservoir A is a representative of this type of reservoir. Starting from its physical properties, a study of the development mechanism was conducted using the tNavigator (22.1) software. A total of 168 sets of numerical experiments were conducted, and 3D maps were innovatively created to optimize the development mode. Building upon the preferred mode, an exploration was carried out for the applicability of gas flooding and the optimization of water flooding schemes for such reservoirs. All experimental results were reasonably validated through Reservoir A. Furthermore, due to the high original pressure in such reservoirs, the injection of displacement media was challenging. Considering economic benefits simultaneously, a study was conducted to explore the rational utilization of natural energy. The research proved that for a reservoir with a permeability of about 10 mD, the suitable development scheme was five-point well pattern, a well spacing of 350 m, water–gas alternating flooding, and an initial oil production rate of 2%. When the reservoir underwent 8 months of depleted development, corresponding to a reduction in the reservoir pressure coefficient to 1.09, the development efficiency was relatively favorable. Over a 15-year production period, the oil recovery reached 29.98%, the water cut was 10.31%, and the reservoir pressure was maintained at around 67.18%. The geology of the newly discovered reservoir is not specific in the early stage of oilfield construction, and this research can help to determine a suitable development scheme. [ABSTRACT FROM AUTHOR]

The effects of high pressure applied during rheo-squeeze casting (RSC) process on the microstructure evolution and corrosion resistance of Mg90.8Zn8.6Y0.6 alloy were investigated. The results reveal that with the increase of pressure, both the average size of α-Mg grains and the lamellar spacing of in-situ formed quasicrystal phase (I–Mg3Zn6Y) are continuously decreased. Meanwhile, the high-pressure results in the increase in the supersaturation of Zn in matrix, the decrease in volume fraction of second phases and the disappearance of Mg7Zn3 phase. The high-pressure contributed to the improvement of corrosion resistance, and the corrosion process was changed from three stages (galvanic corrosion, filiform corrosion and pitting corrosion) to two stages (galvanic corrosion and pitting corrosion), which was mainly attributed to the supersaturation of Zn in matrix, the continuous distribution of finer I-phase and the disappearance of Mg7Zn3.

Nanostructured (FeCoNi)70Ti10B20 (at%) alloy was synthesized by mechanical alloying from elemental powder mixture of Fe, Co, Ni, Ti and B using ball milling. The effect of ball milling time on the evolution of structure and morphology was investigated by X-ray diffraction, scanning and transmission electron microscopy and differential thermal analysis. It was observed that the formation of solid solution of (FeCoNi)70Ti10B20 started from the very onset of the milling process. Crystallite size and lattice strains seemed to be leveled off after 20 h of milling with no further major changes. The milling process for longer periods introduced severe plastic deformations causing formation of amorphous phase of (FeCoNi)70Ti10B20. The amorphous alloy composition was confirmed by energy dispersive X-ray spectroscopy analysis that showed an excellent homogeneity of the alloying elements. The phase stability of the mechanically alloyed amorphous sample was further verified by employing high-temperature and high-pressure studies. The alloy samples heat-treated at 700 °C revealed crystallization of the amorphous phase. However, synchrotron-based high-pressure ambient temperature X-ray diffraction studies confirmed that the amorphous phase of the alloy remained stable up to the pressure of 30 GPa. The 50 h milled sample after being annealed at 350 °C showed improvement in the soft magnetic properties of the alloy, which was due to the probable elimination of the residual stress in the amorphous phase of the alloy powders.

Safety and reliability are the major challenges to face for the development and acceptance of hydrogen technology. It is therefore crucial to deeply study material compatibility, in particular for tribological components that are directly in contact with hydrogen. Some of the most critical parts are sealing materials that need increased safety requirements. In this study, the fretting behavior of several elastomer materials were evaluated against 316L stainless steel in an air and hydrogen environment up to 10 MPa. Several grades of cross-linked hydrogenated acrylonitrile butadiene (HNBR), acrylonitrile butadiene (NBR) and ethylene propylene diene monomer rubbers (EPDM) were investigated. Furthermore, aging experiments were conducted for 7 days under static conditions in 100 MPa of hydrogen followed by rapid gas decompression. Fretting tests revealed that the wear of these compounds is significantly affected by the hydrogen environment compared to air, especially with NBR grades. After the aging experiment, the friction response of the HNBR grades is characterized by increased adhesion due to elastic deformation, leading to partial slip.