Wide Range Of Pressures Research Articles

A comprehensive DFT study of the optoelectronic, mechanical, and thermoelectric properties of Rb[formula omitted]NaScCl[formula omitted] double perovskite implying different pressures

Double perovskite materials possess exceptional properties that render them suitable for application in various sectors and technologies. In this study, we explore the electronic, optical, thermoelectric, and mechanical properties of Rb2NaScCl6, a double perovskite devoid of toxicity, across a wide pressure range from 0 GPa to 200 GPa using density functional theory. Structural and mechanical stabilities are evaluated through tolerance and octahedral factors, as well as elastic constants. The direct band gap of this material is found to be 3.91 eV at 0 GPa pressure. The band gap of this material increases with pressure up to 20 GPa and its value is 4.41 eV at the pressure of 20 GPa; however, its value decreases after that pressure and becomes 2.55 at 200 GPa pressure. Importantly, the optical properties demonstrate that the absorption coefficient lies mostly within the ultra-violet range at normal atmospheric pressure; however, it displays effective absorption in the visible range at high pressure. In addition, the material’s ductile nature is verified using Pugh’s ratio, Cauchy’s pressure, and Poisson’s ratio at different pressures. Moreover, the stiffness of the material increases along with the raising of pressure. Finally, an exploration of the thermoelectric properties reveals that the material demonstrates favorable thermoelectric attributes. Therefore, our material exhibits promising candidates for utilization in diverse sectors, particularly in the realm of new energy production applications.

Transformation of Diffusion and Local Structure of CH4 , CO2 , SO2 and H2 O Mixtures in Graphene Under Wide Temperature and Pressure Range: A Molecular Dynamics Simulation Study.

As a material with high specific surface area and excellent chemical stability, graphene exhibited remarkable adsorption and separation performance as well as a wide range of potential applications. The graphene layer played a significant role in influencing gas transmission. In this study, we employed molecular dynamics simulation to investigate the diffusion characteristics and local structures of a mixed system consisting of CH4 , CO2 , SO2 and H2 O. Additionally, we further examined the transformation of the behavior of these mixtures within graphene layers. The order of diffusion coefficients of the four molecules without graphene was H2 O>SO2 >CO2 ≫CH4 . However, in the double-layer graphene, the order changed to CH4 >CO2 ≫H2 O>SO2 . Higher temperatures and lower pressures were found to facilitate gas diffusion. Temperature and pressure had great effects on the local structures of CH4 , CO2 and SO2 , while their impact on H2 O was limited due to the extensive network of hydrogen bonds formed by H2 O molecules. The statistical results of average coordination number revealed that CH4 tended to aggregate with itself, whereas CO2 and SO2 exhibited a tendency to aggregate with H2 O. The graphene structure enhanced the separation and transportation of CH4 from mixed systems.

Mapping the waste heat recovery potential of CO2 intercooling compression via ORC

The goal of the present work is the systematic mapping of the electricity savings potential of waste heat recovery (WHR) from CO2 compression intercoolers via Organic Rankine Cycle (ORC) technology. Α generalized approach covering a broad range of target CO2 discharge pressures from 50 to 500 bar for 3 to up to 8 compression stages is followed. The maximum, theoretical electricity savings based on the exergy of the heat transfer fluid (HTF) used for intercooling range between 10 % and 24 %. Considering the exergy efficiency of optimized air-cooled ORCs operating with alkanes and hydrofluoroolefins for HTF temperatures between 70 °C and 130 °C, the maximum electricity savings ratio (i.e., the electricity savings compared to the total electricity consumption of the compression unit) is about 5 %, while the installed power of the WHR-ORC ranges from about 3 to 23 kWe per kg/s of compressed CO2. Because of the intense variability of CO2 specific heat capacity over a wide range of pressures, there is a very strong dependence of the waste heat potential on the final discharge pressure and number of stages. Through optimized mixing of the HTF streams, the performance of the WHR-ORC can be improved for particular discharge pressure ranges. Proper sizing of the ORC air-cooled condenser for minimizing air-side pressure drop is critical to ensure the feasibility of WHR-ORCs. According to a techno-economic analysis, WHR-ORCs can result in discounted payback periods from 6 to 12 years and 2.5 to 4 years for 4000 and 8000 operating hours, respectively.

Multidisciplinary high-throughput screening of metal–organic framework for ammonia-based green hydrogen production

This study presents a comprehensive, multidisciplinary approach to high-throughput screening (HTS) of metal–organic frameworks (MOFs) for efficient ammonia-based green hydrogen production. Previous HTS methods, relying on molecular simulations, often estimate adsorption uptakes under constant conditions, leading to inadequate evaluation of MOFs for practical applications where competitive adsorption and varying operating conditions are critical. To address this limitation, we propose a multidisciplinary HTS method employing an efficient computational algorithm that minimizes the number of molecular simulations while generating isotherm models across a wide pressure range. Our algorithm strategically selects simulations for further analysis based on initial results. Using this innovative approach, we screened 12,020 MOFs. Furthermore, as the next step of the multidisciplinary approach, we performed pressure swing adsorption (PSA) process simulations to assess MOFs’ potential for purifying green hydrogen derived from decomposed ammonia, which can be produced by sustainable energy sources and transported intercontinentally. The top-performing MOFs were evaluated for stability based on literature data and MOFSimplify, a neural network model estimating thermal stability. By considering adsorption process operation and MOF stability, the proposed HTS methodology identified 10 high-performing materials, with RAVXIX ranking as the top adsorbent. This comprehensive evaluation advances the search for efficient MOFs in green hydrogen production, contributing to the development of a more sustainable hydrogen-based economy.

All-atom molecular dynamics simulation of structure, dynamics and mechanics of elastomeric polymer materials in a wide range of pressure and temperature

Static and dynamic performance of BR, NR and SBR in a wide range of temperature and pressure.

A cross-scale honeycomb architecture-based flexible piezoresistive sensor for multiscale pressure perception and fine-grained identification.

Trade-off between sensitivity and the pressure sensing range remains a great challenge for flexible pressure sensors. Micro-nano surface structure-based sensors usually show high sensitivity only in a limited pressure regime, while porous structure-based sensors possess a broad pressure-response range with sensitivity being sacrificed. Here, we report a design strategy based on a cross-scale architecture consisting of a microscale tip and macroscale base, which provides continuous deformation ability over a broad pressure regime (10-4-104 kPa). The cross-scale honeycomb architecture (CHA)-based piezoresistive sensor exhibits an excellent sensitivity over a wide pressure range (0.5 Pa-0.56 kPa: S1 ∼ 27.97 kPa-1; 0.56-20.40 kPa: S2 ∼ 2.30 kPa-1; 20.40-460 kPa: S3 ∼ 0.13 kPa-1). As a result, the CHA-based sensor shows multiscale pressure perception and fine-grained identification ability from 0.5 Pa to 40 MPa. Additionally, the cross-scale architecture will be a general structure to design other types of sensors for highly sensitive pressure perception in a wide pressure range and its unit size from microscale to macroscale is beneficial for large-scale preparation, compared with micro-nano surface structures or internal pores.

Robust and rapid partitioning in thermoplastic.

Partitioning is the core technology supporting digital assays. It divides a sample into thousands of individual reactors prior to amplification and absolute quantification of target molecules. Thermoplastics are attractive materials for large scale manufacturing, however they have been seldomly used for fabricating partitioning arrays. Patitioning in thermoplastic devices has proven difficult due to the challenge of efficiently displacing the air trapped in the nanoliter structures during priming of thousands of chambers. Here, we report the design of an array of chambers made of thermoplastics where the progression of the liquid-air interface is controlled by capillary effects. Our device performs robust partitioning over a wide range of pressures and can be actuated at low pressure by a simple micropipette. Our thermoplastic device lays the foundation to cost-effective and instrument-free partitioning platforms, which could be deployed in low-resource settings.

Modelling the solubility of gases in aqueous solutions with a focus on geothermal applications– assessment and benchmarking of two free software packages

The interactions between aqueous solutions, gases, and minerals dictate the extent of issues such as scaling, degassing, and corrosion, which have a major impact on the performance of a vast number of industrial applications (e.g., geothermal plants, oil and gas production facilities, natural gas storage in saline aquifers, flue gas scrubbing, carbon sequestration, etc.). Among the different software programs available for aqueous chemistry calculations, Phreeqc and Reaktoro were tested and validated against a wide dataset of gas solubility measurements. For the datasets considered, the two programs essentially led to the same outcome with only a few discrepancies observed. Yet, the agreement between the models and experimental data was greatly affected by the selected database. The models implemented in Phreeqc and Reaktoro were also compared with the experimental bubble point pressure of fluids sampled at several geothermal wells. The satisfactory performance of both Phreeqc and Reaktoro for describing different chemical systems at a wide range of pressures and temperatures showcases their versatility and practicality for assisting in the design and optimization of various processes relevant to the energy transition (e.g., geothermal exploitation, CO2/H2 transport and storage).

Numerical simulation study on microdischarge via a unified fluid model

Numerical simulation has become an indispensable tool in the study of gas discharge. However, it is typically used to reveal microscopic properties in a discharge under specific conditions. In this work, a unified fluid model for discharge simulation is introduced in detail. The model includes the continuity equation, the energy conservation equation of the species (electrons and heavy particles), and Poisson’s equation. The model takes into account some processes such as cathode electron emission (secondary electron emission and thermionic emission), reaction enthalpy change, gas heating, and cathode heat conduction. The full current-voltage characteristic (CVC) curve covers a range of discharge regimes, such as the Geiger-Müller discharge regime, Townsend discharge regime, subnormal glow discharge regime, normal glow discharge regime, abnormal glow discharge regime, and arc discharge regime. The obtained CVC curve is consistent with the results in the literature, confirming the validity of the unified fluid model. On this basis, the CVC curves are obtained in a wide pressure range of 50–3000 Torr. Simulation studies are carried out focusing on the discharge characteristics for microgap of 400 µm at pressures of 50 Torr and 500 Torr, respectively. The distributions of typical discharge parameters under different pressure conditions are analyzed by comparison. The results indicate that the electric field in the discharge gap is uniform, and that the space charge effect can be ignored in Townsend discharge regime. The cathode fall region and the quasi-neutral region both appear in glow discharge regime, and the space charge effect is significant. In particular, the electric field reversal occurs in abnormal discharge regime due to the heightened particle density gradient. The electron density reaches about 10<sup>22</sup> m<sup>–3</sup> in arc discharge regime dominated by thermionic emission and thermal ionization, with the current density increasing. The gas temperature peak is 11850 K when the pressure is 500 Torr, and the cathode surface is heated to nearly 4000 K due to heat conduction. The present model can be used to simulate gas discharge across a wide range of condition parameters, promoting and expanding fluid model applications, and assisting in a more comprehensive investigation of discharge parameter properties.

Exploring the Mpemba effect: a universal ice pressing enables porous ceramics.

Piezoceramics with global porosity and local compaction are highly desired to exploit the combination of mechanical and electrical properties. However, achieving such a functional combination is challenging because of the lack of techniques for applying uniform pressure inside porous ceramic green parts. Nature provides many examples of generating strong forces inside the macro and micro channels via the state transformation of water. Inspired by these phenomena, we present a technique of "ice and fire", that is, water freezing (ice pressing) and high-temperature sintering (fire), to produce ideal porous piezoceramics. We introduce a new compaction method called the "ice pressing method", which manipulates liquid phase transition for compaction. This method has several advantages, including uniform pressure distribution, a wide pressure range, high effectiveness, and selective freezing. It can generate an ultrahigh pressure of up to 180 MPa on the piezoceramic green skeletons in minutes while retaining their functional pore structures. By exploiting the Mpemba phenomenon, we further accelerate the compaction procedure by 11%. The first ice-pressed and second fire-consolidated lead zirconate titanate (PZT) ceramics are highly densified and exhibit an outstanding piezoelectric response (d33 = 531 pC N-1), comparable to conventional pressed bulk counterparts and 10-20 times higher than those of unpressed materials. The novel ice pressing method breaks the limitation of lacking a compaction technique for porous ceramics. The versatile and effective ice pressing method is a green and low-cost route promoting applications in sensors, acoustics, water filtration, catalyst substrates, and energy harvesting.

A two-region model for azimuthal striations in an inductively coupled plasma

Abstract A two-region discharge model with a perturbation analysis was developed for the azimuthal striations observed in an inductively coupled plasma with an immersed cylindrical coil at pressures of 75–1500 mTorr. This model partitions the discharge area into two distinct regions: a bright region near the coil with intense excitation and ionization processes, and a darker region extending from the boundary of the bright core to the chamber wall. This partition reflects the experimental observation that striations are restricted to the vicinity of the coil and this phenomenon becomes more pronounced with increasing pressure. Through a perturbation analysis, the model indicates that the azimuthal striations manifest only below a critical power threshold, and this threshold decreases with pressure, which aligns with the experimental observations. Additionally, the model-predicted number of striations is in good agreement with the experiment over a wide pressure range.

Synergistic advancements in high-performance flexible capacitive pressure sensors: structural modifications, AI integration, and diverse applications.

The development of flexible pressure sensors for monitoring human motion and physiological signals has attracted extensive scientific research. However, achieving low monitoring limits, a wide detection range, large bending stresses, and excellent mechanical stability simultaneously remains a serious challenge. With the aim of developing a high-performance capacitive pressure sensor (CPS), this paper introduces the successful preparation of a single-walled carbon nanotube (SWNT)/polydimethylsiloxane (S-PDMS) composite dielectric with a foam-like structure (high permittivity and low elasticity modulus) and MXene/SWNT (S-MXene) composite film electrodes with a micro-crumpled structure. The above structurally modified CPS (SMCPS) demonstrated an excellent response output during pressure loading, achieving a wide pressure detection range (up to 700 kPa), a low detection limit (16.55 Pa), fast response/recovery characteristics (48/60 ms), enhanced sensitivity across a wide pressure range, long-term stability under repeated heavy loading and unloading (40 kPa, >2000 cycles), and reliable performance under various temperature and humidity conditions. The SMCPS demonstrated a precise and stable capacitive response in monitoring subtle physiological signals and detecting motion, owing to its unique electrode structure. The flexible device was integrated with an Internet of Things module to create a smart glove system that enables real-time tracking of dynamic gestures. This system demonstrates exceptional performance in gesture recognition and prediction with artificial intelligence analysis, highlighting the potential of the SMCPS in human-machine interface applications.

Memory effect and coexistence of negative and positive photoconductivity in black phosphorus field effect transistor for neuromorphic vision sensors.

Black phosphorus (BP) field-effect transistors with ultrathin channels exhibit unipolar p-type electrical conduction over a wide range of temperatures and pressures. Herein, we study a device that exhibits mobility up to 100 cm2 V-1 s-1 and a memory window up to 1.3 μA. Exposure to a supercontinuum white light source reveals that negative photoconductivity (NPC) and positive photoconductivity (PPC) coexist in the same device. Such behavior is attributed to the chemisorbed O2 molecules, with a minor role of physisorbed H2O molecules. The coexistence of NPC and PPC can be exploited in neuromorphic vision sensors, requiring the human eye retina to process the optical signals through alerting and protection (NPC), adaptation (PPC), followed by imaging and processing. Our results open new avenues for the use of BP and other two-dimentional (2D) semiconducting materials in transistors, memories, and neuromorphic vision sensors for advanced applications in robotics, self-driving cars, etc.

Theoretical and kinetic study of the thermal decomposition mechanism of long chain aldehydes

The mechanism of decomposition of the butanal and pentanal long chain aldehydes was investigated using the ab initio transition state theory-based master equation approach. The rate constants of the homolytic bond scission reactions of butanal and pentanol leading to the formation of CHO+C3H7, CH2CHO+C2H5, C2H4CHO+CH3, C3H7CO+H, C2H5ĊHCHO+H and CH2CHO+C3H7, C2H4CHO+C2H5, C3H6CHO+CH3, C4H9CO+H, C3H7ĊHCHO+H, respectively, as well as of the reverse barrierless recombination channels, were determined using Variable Reaction Coordinate Transition State Theory. The potential energy surfaces were determined at the multireference CASPT2/aug-cc-pVTZ level on ωB97X-D/jun-cc-pVTZ structures, while stochastic samplings were performed at the CASPT2 level using a (4e,4o) active space. Rate laws for the alkyl+R-CHO, H+R-ĊHCHO, and H+R-ĊO classes of reactions were then determined. Rate constants of H-abstraction reactions and of the three body butanal →CO+H2+C3H6 channel were determined using ωB97X-D/jun-cc-pVTZ structures and Hessians and CCSD(T) energies, extrapolated to the complete basis set. It was found that the calculated homolytic bond scission reactions are faster by a factor of 2–3 with respect to literature previous estimates. The calculated reaction rates were inserted in the CRECK kinetic scheme and used to simulate literature speciation data of butanal and pentanal pyrolysis in shock tubes and ignition delay times, finding that their inclusion into the kinetic scheme enhances the predictive capabilities of the mechanism. The aldehyde decomposition mechanism and the rate constants determined in this study are suitable to be used to interpret and predict the reactivity of aldehydes in a wide range of temperatures and pressures.

Development of methods for calculating thermal conductivity of gas condensates-alternative motor fuels

The article is devoted to the development of methods for calculating the thermal conductivity of complex hydrocarbon mixtures such as gas condensates, which are widely used as components for motor and jet fuels. The work was carried out on the basis of the results of experimental studies of thermal conductivity of the eight most representative deposits in Central Asia in terms of group hydrocarbon composition. An analysis of existing equations for calculating the thermal conductivity of liquid petroleum products and the possibility of their use for gas condensates was carried out. A number of new equations are presented for calculating the thermal conductivity of gas condensates depending on the group hydrocarbon composition in a wide range of temperatures and pressures.

Consistent interpretation of isotope and chemical oxygen exchange relaxation kinetics in SrFe0.85Mo0.15O3-δ ferrite.

This paper is devoted to the study of phase composition and kinetic and thermodynamic characteristics of Mo-doped strontium ferrite SrFe0.85Mo0.15O3-δ (SFM15) under oxygen-conducting membrane working conditions. Single-phase SFM15 with a cubic Pm3̄m structure was synthesized using a ceramic method. It was shown that the molybdenum introduction stabilizes the perovskite cubic structure over a wide range of oxygen pressures and temperatures, preventing the bulk phase transition at high temperatures. Oxygen exchange constants, diffusion coefficients and activation energy of oxygen exchange were obtained using oxygen relaxation and isotopic exchange techniques, and the obtained values are consistent with known literature data. It was shown that the surface reaction rates obtained using chemical and tracer relaxation methods are quantitatively comparable with each other, despite significantly different experimental conditions. This result not only confirms the reliability of the data obtained by independent methods, but also allows one to expand the area of physical conditions for studying the kinetics of oxygen transfer where another method has technical or methodological limitations.

Dual-emitting cyclometalated Ir(III) complexes with salicylaldimine-bound fluorophores for ratiometric oxygen sensing.

A new class of oxygen-sensing dual-emitting cyclometalated Ir(III) complexes is described. They function as ratiometric sensors that combine the blue fluorescence from coumarin as a self-referenced internal standard with yellow to red phosphorescence from bis-cyclometalated iridium complexes. The compounds have phosphorescence quantum yields up to 15%, lifetimes ranging from 0.23 to 9.4 μs, and are capable of sensing a wide range of O2 partial pressures.

Outer-context determinants on the implementation of school-based interventions for LGBTQ+ adolescents.

Schools are critical venues for supporting LGBTQ+ youth well-being. Implementing LGBTQ-supportive practices can decrease experiences of stigmatization, discrimination, and victimization that lead to adverse mental health outcomes like anxiety, depression, and suicidality. However, schools are also subject to a wide range of outer-context pressures that may influence their priorities and implementation of LGBTQ-supportive practices. We assessed the role of emergent outer-context determinants in the context of a 5-year cluster randomized controlled trial to study the implementation of LGBTQ-supportive evidence-informed practices (EIPs) in New Mexico high schools. Using an iterative coding approach, we analyzed qualitative data from annual interviews with school professionals involved in EIP implementation efforts. The analysis yielded three categories of outer-context determinants that created challenges and opportunities for implementation: (a) social barriers related to heterocentrism, cisgenderism, and religious conservatism; (b) local, state, and national policy and political discourse; and (c) crisis events. By exploring the implications of outer-context determinants for the uptake of LGBTQ-supportive practices, we demonstrate that these elements are dynamic-not simply reducible to barriers or facilitators-and that assessing outer-context determinants shaping implementation environments is crucial for addressing LGBTQ health equity.

Phase Behavior of Biodegradable Poly(L-lactic acid) in Supercritical Solvents and Cosolvents

Poly(L-lactic acid) (PLLA), a biodegradable polymer from plant sources, is widely employed in biomedical applications for its biocompatibility and versatile mechanical properties. However, comprehending its phase behavior in various solvents poses a challenge for broader applications. In this study, the phase behavior of the polymer was investigated in various solvent and cosolvent media and combinations at a wide range of temperatures and pressures to gain insight into the polymer properties. PLLA of varying intrinsic viscosity (IV): [0.15dl/g, with an estimated weight average molecular weight (Mw) range of approximately: 1,600 to 2,400g/mol; 1.0dl/g (Mw): 100,000g/mol); and 1.8dl/g (Mw): 80,000 to 100,000g/mol] was employed for this study. The phase behavior of the polymer across different compositions of PLLA and solvent (CH2F2, CHF3, CO2, DME, F-22) in a wide range of temperatures from 333 to 425K and high pressure 1.55 to 172MPa was investigated. Miscibility of PLLA in DME and F-22 is predicted to be higher with increasing in concentration than the other cosolvents. Furthermore, in the case of the supercritical solvent CHF3 and DME the phase transition pressure curve of PLLA was observed to exhibit a lower critical solution temperature (LCST) type with a positive gradient with increasing temperature. However, lower phase transition pressure was noticed for lower molecular weight PLLA in supercritical solvent CHF3 and DME, i.e., of the order IV 0.15dl/g<IV 1.0dl/g<IV 1.8dl/g. The phase transition pressure of PLLA (IV 1.8dl/g) in solvent CO2 with increasing the concentration of co-solvent (F-22, DME) from 0 to ~97wt% shifted from UCST to LCST type. The LCST curve of PLLA (IV 0.15) in DME intersects with the vapor(V)-liquid(L) curve at T: 353K and P below 5MPa, indicating the coexistence of V+L phases.

Ultra-slow ammonia flame speeds — A microgravity study on radiation

Ammonia/air flames burn slowly and are consequently affected by buoyancy-, radiation-, and stretch-related uncertainties more than many conventional hydrocarbon fuels. In this work, unique buoyancy-free ammonia/air flame speed data were acquired and analyzed, specifically considering the impact of radiation. First, outwardly propagating ammonia/air flames near the propagation limits were accurately measured under microgravity using two simultaneous techniques. Flame radius evolution was captured by a high-speed Schlieren arrangement (optical method) in a near-isobaric regime. Accompanying, pressure rise was measured and subsequently used for flame speed extraction during near-isentropic gas compression. A profound nonlinear dependence of flame propagation speed on stretch was captured over the optical results in the observable range of the current setup, which illustrates the limitations of the optical method in comparison to the pressure-rise method. Radiation-corrected optical and pressure-rise results have shown good agreement along multiple isentropes, thereby cross-validating applied methodologies and highlighting very good consistency of the acquired data. Pressure-rise data analysis has shown sensitivity in the assessment of kinetic mechanisms to the radiation effect. In the absence of appropriate radiation correction for flame speed data, misinterpretations may arise regarding the accuracy of kinetic models, introducing challenges in the development of accurate kinetic models. The performance of the chemical kinetic models was quantified in a wide range of unburned gas temperatures (< 500K) and pressures (< 9.3bar) against distinctive experimental flame speed data with and without radiation correction acquired under microgravity indicating good performance of the Han et al. (2019) model.