The study of phase transitions in materials under high pressure and high temperature is a very active research field. In the last few decades, many important discoveries have been made thanks to the ...development of experimental techniques and computer simulation methods. Many of these achievements affect various research fields ranging from solid-state physics, chemistry, and materials science to geophysics. They not only involve deepening knowledge on solid–solid phase transitions, but also a better understanding of melting under compression. These modern discoveries, as well as the impact of pressure on structural, chemical, and physical properties, are central to the current Special Issue. Amongst other topics, it places particular emphasis on phase transitions and their effects on different physical properties.
Clean-label foods have gained a lot of attention since it meets consumers’ interests in minimally processed food having a minimal number of ingredients and free from artificial additives. Increased ...interest in premium quality food products stimulated the integration of high-pressure technologies in food processing compared to conventional thermal processing. While commercial thermal pasteurization is effective in preserving beverages; high pressure-based processing technologies ensure a substantial decrease in microorganisms and spoilage enzymes as well as ensuring minimal impact on the nutrients content and sensory quality. Therefore, this article reviews the potential of high-pressure processing, high-pressure homogenization, ultrahigh-pressure homogenization, high-pressure carbon dioxide/supercritical carbon dioxide, and their updated applications to better preserve the quality of fruit juices and beverages. Pressure-based technologies can assist in reducing the number of ingredients by eliminating the need for certain additives for product stability and preservatives used for food safety and shelf-life extension. Available data highlight important limitations for clean-label food production, represented by the need to establish pressure optimization, microbiological and safe handling in the absence and/or in the presence of a low level of synthetic preservatives. More research is needed for reliable process validation with a focus on process characterization (temperature fields, thermal heterogeneity, and residence time distributions) and sterilization indicators, or mixtures thereof, to implement this promising technology.
•Clean label foods are consumer-recognized as natural, premium, and wholesome.•High-pressure based technologies have been investigated to stabilize beverages.•High pressure processing retains freshness as well as nutritional/sensorial quality.•High-pressure technologies are combined with natural additives or other technologies.•Combination of high pressure and CO2 mitigates the deficiency of using each treatment alone.
A systematic structure search in the La–H and Y–H systems under pressure reveals some hydrogen-rich structures with intriguing electronic properties. For example, LaH10 is found to adopt a ...sodalite-like face-centered cubic (fcc) structure, stable above 200 GPa, and LaH₈ a C2/m space group structure. Phonon calculations indicate both are dynamically stable; electron phonon calculations coupled to Bardeen–Cooper–Schrieffer (BCS) arguments indicate they might be high-Tc
superconductors. In particular, the superconducting transition temperature Tc
calculated for LaH10 is 274–286 K at 210 GPa. Similar calculations for the Y–H system predict stability of the sodalite-like fcc YH10 and a Tc
above room temperature, reaching 305–326 K at 250 GPa. The study suggests that dense hydrides consisting of these and related hydrogen polyhedral networks may represent new classes of potential very high-temperature superconductors.
Synthetic diamond competes with the conventional cemented carbide (WC–Co) tool material in some applications due to its extreme hardness. However, so far, these materials have not been compared from ...a life cycle perspective regarding their environmental and resource impacts. The aims of this study are i) to provide detailed life cycle assessment (LCA) results for industrial polycrystalline diamond (PCD) production from diamond grit produced via high-pressure high-temperature (HPHT) synthesis and ii) to conduct the first comparative LCA of PCD and WC-Co tools for the cases of wood working and titanium alloys machining. The results show that the main hotspot in HPHT synthesis of diamond grit, which is the main precursor to PCD, is the use of WC-Co in the high-pressure apparatus. In PCD tool production, the electricity input and the use of tungsten and molybdenum contribute the most to environmental and resource impacts. The environmental and resource impacts of the PCD tool production can be reduced with 53–83% if solar electricity and full WC-Co recycling is applied. The comparison shows high environmental and resource improvements when substituting WC-Co tools with PCD tools in wood working, but not in titanium alloys machining.
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•First life cycle assessment comparing PCD and WC-Co in machining.•PCD is environmentally preferable to WC-Co in wood working.•WC-Co is environmentally preferable to PCD in titanium alloys machining.•Applying solar electricity in PCD production greatly reduce environmental impacts.•Ready-to-use LCA data for industrial production of PCD and diamond grit.
An organic–inorganic halide CH3NH3SnI3 perovskite with significantly improved structural stability is obtained via pressure‐induced amorphization and recrystallization. In situ high‐pressure ...resistance measurements reveal an increased electrical conductivity by 300% in the pressure‐treated perovskite. Photocurrent measurements also reveal a substantial enhancement in visible‐light responsiveness. The mechanism underlying the enhanced properties is shown to be associated with the pressure‐induced structural modification.
The review discusses the pitfalls of the matrix effect in mass spectrometry detection hyphenated to liquid chromatography separation. Matrix effect heavily influences both qualitative and ...quantitative analyses, giving rise to suppression or enhancement of the signal. As generally recognised, the predominant cause is the presence of undesired components that co-elute in the chromatographic separation and alter the ionisation process. The interfering species can be components of the sample, compounds released during the pre-treatment/extraction process or reagents added to the mobile phase to improve chromatographic resolution. The different mechanisms proposed in literature to explain the suppression or the enhancement of the signal both in electrospray and atmospheric pressure chemical ionisations are presented and the results observed in the different experimental conditions are compared and discussed. All data together lead to conclude that the chemical properties of the target analyte, the kind of matrix, the matrix to analyte concentration ratio, the extraction process, the chromatographic conditions as well as the kind of the mass spectrometry instrumentation and the ionisation conditions can play a role. Likely all these potential causes act in a synergic way and the final effect observed is hardly due to only one of them. Depending on an unpredictable combination of conditions, signal suppression or enhancement can be observed. The review discusses the matrix effects observed in HPLC–MS and HPLC–MS/MS analysis proposes hypotheses to explain the observed behaviours and proposes methods and strategies to overcome the matrix effects.
SUMMARY
We complete the development and description of a thermodynamic method for the computation of phase equilibria and physical properties of multiphase mantle assemblages. Our previous paper ...focused on the computation of physical properties. In this paper, our focus shifts to the phase equilibria. We further develop our theory to specify the ideal and excess contributions to solution properties and derive properties of multiphase assemblages. We discuss our global inversion strategy for determining the values of the free parameters in our theory and compare inverted parameter values with expectations based on scaling arguments. Comparisons between our method and experimental phase equilibria data encompass the pressure–temperature regime of Earth's mantle. Finally, we present applications of our method that illustrate how it may be used to explore the origins of mantle structure and mantle dynamics. Continuing rapid advances in experimental and theoretical petrology and mineral physics have motivated an expansion of the scope of our model via the addition of several new phases, and of the soda component: an appendix lists all parameters in our model and references to the experimental and theoretical studies that constrain them. Our algorithm for global minimization of the Gibbs free energy is embodied in a code called HeFESTo, and is detailed in a second appendix.
Long-duration extreme cold events in China were often characterized by strong simultaneous high-pressure anomalies (SHA) over the Ural and the North Pacific regions, e.g., 2018. It is unclear how ...human activity and the SHA influenced the long-duration extreme cold events in China, respectively. Herein, we investigated variations in such long-duration cold events during the past 60 years and contributions of human activity and the related atmospheric circulation pattern. Results show since 2008, the coldest periods in each winter in eastern China have become colder than those in the 1980s and 1990s, which caused an enlarging temperature difference between China and the Northern Hemisphere. We found that an increase in SHA resulted in the cold events colder and longer than a single high anomaly, through a combined reinforcing effect on the high-latitude ridges and a blocking effect on eastward movement of the East Asian trough. The UHA dominates the intensity of cold events, while the PHA modulates the duration of cold air. Comparative analysis indicated that, the enhanced SHA offsets part of the anthropogenic warming effect, resulting in extreme cold events still occurring in warm winters. And strong SHA can increase the probability of the strong cold events to about twice that with weak SHA. It is meaningful to deeply understand variations of cold events under global warming.
The formation of ω-phase under high-pressure torsion (HPT) has been studied in Ti–Fe alloys. Seven alloys with Fe concentration from 0 to 10 wt % have been annealed between 600 and 950 °C, quenched ...and HPT-treated at 7 GPa, 1 rpm, 5 and 0.1 anvil rotations (equivalent strain eeq = 156 and = 3.1, respectively). The strain after 0.1 rot. corresponds to the transient state of HPT, and that after 5 rot. corresponds to the HPT steady-state and to the dynamic equilibrium between formation and annihilation of microstructure defects. A defect-rich high-pressure ω-phase forms after HPT and persists in the samples also after the pressure release. The amount of retained ω-phase after HPT depends on the iron concentration. It increases from 40% in pure titanium, reaches maximum of 95% at 4 wt % Fe and then decreases again to 10% at 10 wt % Fe. It is because the addition of iron influences the lattice parameters in β and ω-phases in a different manner. The minimal lattice mismatch between β- and ω-phases is reached at 4 wt % Fe. A good conformity between the lattices of the β- and ω-phases enhances the probability of the martensitic (diffusionless) β→ω transformation. Based on the XRD and TEM observations, the crystallography and mechanisms of α→ω and β→ω phase transformations (which can be diffusionless as well as controlled by mass transfer) under the influence of pure shear by HPT are discussed.
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The Key Laboratory of High-temperature and High-pressure Study of the Earth’s Interior belongs to the Institute of Geochemistry, Chinese Academy of Sciences, China. It is a unique and authoritative ...key laboratory at the provincial and ministerial levels. The Key High-Pressure Laboratory is primarily focused on the high-temperature and high-pressure experimental sciences, in combination with filed geophysical observation, theoretical calculation and advanced analysis tests in order to explore the chemical composition, cycling structure, geological state, material circulation, etc., of deep Earth. The mainstream research subjects of the Laboratory mainly include: research and development of experimental platforms and measurement techniques at high temperatures and high pressures; high-pressure material synthesis and hot-pressed sintering techniques; physical and chemical characterizations (e.g. electrical conductivity, thermal conductivity, ultrasonic wave velocity, etc.) of minerals and rocks at conditions of high pressure and different oxygen fugacities by virtue of representative high-pressure apparatus, including autoclaves, piston cylinders, multi-anvil presses, diamond anvil cells and shock waves; high-pressure physiochemical behavior and storage states in the geological fluid and melt of deep Earth interior; high-pressure theoretical calculations; and high-pressure applications in the service of national economical and societal development.
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