High-pressure Measurements Research Articles

Racial and Ethnic Disparities in Pediatric Counseling on Nutrition, Lifestyle, and Weight

Pediatric obesity and hypertension are highly correlated. To mitigate both conditions, provision of counseling on nutrition, lifestyle, and weight to children with high blood pressure (BP) measurements is recommended. To examine racial and ethnic disparities in receipt of nutrition, lifestyle, and weight counseling among patients with high BP at pediatric primary care visits stratified by patients' weight status. This was a post hoc secondary analysis of the BP-CATCH study, a matched, stepped-wedge cluster randomized clinical trial investigating the best methods to screen children with high BP measurements and manage their care. Urban, suburban, and rural pediatric primary care practices across the US with a multidisciplinary team of at least 1 physician, 1 nurse and another practice associate, and a hypertension specialist for their practice group submitted baseline data from clinical encounters documented between November 2018 and January 2019. Practices identified the first 17 eligible patients with high BP measurements each month. This analysis was conducted from October 2023 to July 2024. Race and ethnicity (Black, Hispanic, White, and other [Asian, multiracial, other races, and unknown race]) and weight status (with or without obesity). Primary outcomes were receipt of counseling on nutrition, lifestyle, and weight during primary care visits. Baseline measures extracted from medical records included demographics, anthropometric measures, and systolic and diastolic BP. Of 2677 participants from 59 practices, 1516 (56.6%) were male; mean (SD) age was 10.8 (5.2) years. A total of 593 (21.1%) were Black; 414 (15.5%), Hispanic; 1111 (41.5%), White; and 559 (20.9%), other race and ethnicity. The overall crude unadjusted rates of receiving counseling were 63.5% (n = 1564 of 2463) for nutrition, 57.6% (n = 1419 of 2462) for lifestyle, 47.5% (n = 571 of 1202) for weight, and 46.4% (n = 1142 of 2461) for all counseling topics. Compared with the other 3 groups, Hispanic participants received significantly higher adjusted rates of nutrition (78.6%; 95% CI, 73.5%-83.8%), lifestyle (69.3%; 95% CI, 63.6%-74.9%), and all 3 (52.1%; 95% CI, 46.1%-58.2%) counseling topics. There were no significant differences in rates of receiving weight counseling between any pairs of groups. These findings were consistent in general among participants without obesity, and no significant pairwise differences were noted among participants with obesity except that nutrition counseling rates were significantly different between White participants and those reporting other race and ethnicity (68.3% [95% CI, 61.1%-75.4%] vs 81.6% [95% CI, 74.2%-89.1%]; Bonferroni-corrected P = .02). This secondary analysis of the BP-CATCH trial found that among children with high BP measurements, racial and ethnic disparities in receiving nutrition, lifestyle, and all 3 counseling topics were significant, although no significant disparities in receipt of weight counseling were noted. Racial disparities in receipt of counseling were not observed in participants with and without obesity. ClinicalTrials.gov Identifier: NCT03783650.

The effect of hydrostatic pressure on electric transport properties of bulk black arsenic phosphorus single crystals

Black arsenic phosphorus AsxP1-x (b-AsxP1-x), as a novel two-dimensional material, has recently attracted great attention owing to their exotic physical properties. Here, we report a systematic study of the pressure dependence of electric transport properties in b-As0.75P0.25 single crystal. At ambient pressure, b-As0.75P0.25 shows an extrinsic semiconducting behavior, and the magnetoresistance (MR) has an obvious dependence on the magnetic field direction, resulting in an anisotropic MR effect. With the applied hydrostatic pressure, the crystal exhibits a tendency towards metallic behavior, whereas at pressures above 1.0-1.3GPa, the resistivity starts to increase at low temperatures. This picture is simultaneously supported by low temperature high-pressure MR measurements. Taking into account the negative and positive contributions to the MR, we have been able to propose a modified two-band model to describe the MR properties. The analysis of the MR data reveals the coexistence of high-mobility electrons and holes with nearly identical carrier densities. Above the critical pressure, the density of the electron that remains dominant increases with pressure while the electron mobility decreases significantly under pressure, leading to a transition in resistivity. This work has implications to both the fundamental understanding of bulk b-As0.75P0.25 and studies of two-carrier correlated materials.

N- to p-Type Conductivity Transition of Lu3N@C80 Due to Anisotropic Deformation of Fullerene and Pyramidalization of Endohedral Clusters.

The endohedral fullerene Lu3N@C80 was examined using in situ high-pressure measurements, which included electrical transport, Fourier-transform infrared spectroscopy, and Raman spectroscopy, in combination with theoretical calculations. Lu3N@C80 was found to undergo a reversible n- to p-type conversion at ∼8.9 GPa. This p-type semiconductor remains stable up to 25 GPa. The fullerene cage collapses at ∼29 GPa, resulting in an irreversible p- to n-type conversion. Raman, infrared, and X-ray absorption spectroscopy reveal that an anisotropic distortion of the carbon cage and a pyramidalization of the planar Lu3N clusters occur during compression. Density functional theory simulations indicate that the p orbitals of C atoms in the fullerene cage primarily contribute to the density of states (DOS). Pressure-induced deformation of the fullerene cage dominates the DOS changes in the conduction and valence bands close to the Fermi level. The findings elucidate the relationship between the conductivity and structural changes in the endohedral clusters.

Dual-mode AT-cut quartz resonant pressure sensor for wide pressure and temperature measurement ranges

In this paper, a dual-harmonic-mode excited resonant pressure sensor with an AT-cut all-quartz sensing element was developed to synergistically achieve a wide measurement range for both temperature and pressure, along with a fast transient response. In this device, the excited third overtone mode indicated the applied pressure, while the beat frequency generated by the overtone and fundamental modes was used for self-temperature compensation. At the same time, the sandwiched all-quartz sensitive structure design effectively addressed the limitations associated with narrow pressure and temperature ranges. Especially, the dual-mode self-temperature sensing mechanism has been validated in the subzero temperature range for the first time. Quartz crystal processing techniques were employed to manufacture the sensor, and key performance metrics were characterized. The experimental results demonstrated that the sensor achieved an accuracy of ± 0.015 % full scale (FS) under a pressure range of 0–120 MPa and a temperature range of −40 to 150 °C. The pressure sensitivity of the overtone frequency was quantified as 365 Hz/MPa, and the beat frequency provided a temperature accuracy of 0.4 °C. Additionally, the developed sensor exhibited fast transient response under dynamic pressure and temperature conditions attributed to its self-temperature compensation capability. Thus, this study provides a practical solution for high-pressure measurements across a wide temperature range, combined with excellent transient performance.

High-Pressure Behaviors of Hydrogen Bonds in Fluorine-Doped Brucite.

Brucite, Mg(OH)2 (P3̅m1, Z = 1), is a prototype material for studying hydrogen bonds in solid hydroxides. In this study, substitutional effects of fluorine (F) on the hydrogen-bonding geometries of hydrogenated and deuterated brucite were investigated under ambient conditions and at high pressure using combined experimental methods of neutron powder diffraction, Raman spectroscopy, and infrared (IR) spectroscopy. Under ambient conditions, neutron powder diffraction results showed that F substitution decreased the donor-acceptor distance and increased the hydroxyl covalent bond lengths of both hydrogenated and deuterated brucite, strengthening the hydrogen bond. Red shifts of the hydroxyl stretching modes also indicated an elongation of d(O-H) and d(O-D). High-pressure neutron diffraction experiments were performed on Mg(OH)1.81F0.19 and Mg(OD)1.74F0.26 up to 7.04 and 10.02 GPa, respectively. For both samples, changes in the hydrogen-bonding geometries did not indicate hydrogen-bond strengthening under high pressure. Compared with Mg(OD)2, the doping of F suppressed the increase of the hydroxyl covalent bond length, the hydrogen-bond angle, and the cone angle, inhibiting pressure-induced hydrogen-bond strengthening. High-pressure Raman and IR absorption spectroscopic measurements on Mg(OD)2 and Mg(OD)1.79F0.21 up to 9.7 and 13.7 GPa confirmed that F substitution restrains pressure-induced hydroxyl elongation.

Comparison of Intraocular Pressure Measurement by iCare Tonometer and Goldman Applanation Tonometer

Objective: To compare the Intraocular Pressure measured by the Goldmann Applanation tonometer with by iCare ic100 tonometer in normal human eye to determine the accuracy and reliability of both methods. Study Design: Comparative cross-sectional study. Place and Duration of Study: Ophthalmology Department, Combined Military Hospital, Quetta Pakistan, from Oct 2022 to Apr 2023. Methodology: Approval was secured prior to enrolling every individual, protecting their privacy throughout the process. All instruments adhered to the manufacturer's guidelines for calibration. A single ophthalmologist assessed the intraocular pressure of all participants. In our study we included 400 eyes (200 right and 200 left) among 200 patients. Initially, study eyes were inspected using a slit lamp. Subsequently, iCare tonometer and Goldman applanation tonometer were employed to gauge the intraocular pressure. Results: Out of 200, 87 patients (43.5%) were male and 113(56.5%) were females. Median age of the patients was 51.00(45-58) years range from 22-77 years. Mean IOP measured by iCare was 19.01±7.86 mmHg and by Goldman applanation tonomter was 20.14±8.15 mmHg. The correlation coefficient value between the readings of two instruments was r=0.866 with significant p value (p< 0.001). Conclusion: The iCare ic100 consistently provides high intraocular pressure measurements (2-3mmHg) compared to the Goldmann Applanation tonometer across various sub Groups.

Highly Conductive Paths in Diamond and their Application in High Pressure Measurements.

Diamonds possess exceptional properties such as high mechanical strength, thermal conductivity, and electrical resistance, making them suitable for various applications, including high-power electronics and optoelectronics. However, fabricating conductive structures in diamond remains a significant technological challenge. In this publication, we present a controlled process for fabricating precise amorphous conductive paths in a monocrystalline diamond using a focused ion beam (FIB) technique. The resistivity and thickness of the fabricated structures were determined, and their morphology was carefully characterized. The results showed that the optimal charge dose for achieving the lowest resistance was found to be 1017 ions/cm2. The fabricated structures exhibited amorphous morphology. Elemental analysis confirmed the presence of gallium ions in the modified material. The resistivity of the conductive paths was determined to be 30 μΩm, which is remarkably low compared to previous studies and only 1-2 orders of magnitude higher than in metals. Additionally, it is shown that this technology has potential applications in high-pressure chambers and the development of high-pressure sensors within diamond anvils. Overall, this study provides valuable insights into fabricating conductive structures on diamonds using FIB and opens up possibilities for diamond electronics.

Pressure-induced anomaly of transport properties and structural transition in layered ferromagnetic metal TlCo2S2

In this work, the structural and transport properties of ferromagnetic metal TlCo2S2 with ThCr2Si2-type crystal structure are systematically studied using high-pressure synchrotron x-ray powder diffraction, electrical transport measurements and first-principles calculations. All the resistances of TlCo2S2 between 1.4 GPa and 5.2 GPa exhibit an upturn at TS and an obvious hysteresis is observed below TS when measured in the cooling and heating processes. As the pressure increases, TS gradually increases and the resistances display a metallic behavior without any anomaly in the whole temperature region above 5.2 GPa, indicating that a possible structural phase transition occurs at TS and is beyond the room temperature above 5.2 GPa. High-pressure x-ray diffraction measurements combined with crystal structure prediction indicate that at room temperature TlCo2S2 undergoes a structural phase transition from a tetragonal phase (I4/mmm) to an orthorhombic structure (Bmab) at Pc ≈6.8 GPa, which is consistent with the results of the resistances under high pressure. Our results indicate that a first-order structural phase transition of TlCo2S2 is induced by high pressure and then results in the anomaly of the electrical transport properties.

Sound velocity measurement based on laser-induced micro-flyers

The measurement of high-pressure sound velocity in solid materials is crucial for developing constitutive equations and equations of state for materials in extreme stress–strain rate conditions. In this study, we propose a novel method for high-pressure sound velocity measurement using laser-induced micro-flyer technology. By optimizing laser driving conditions and target structure design, we measure high-pressure sound velocity using the “reverse-impact geometry” approach. The well-established Photon Doppler Velocimetry system allows for high-precision, single-shot measurements of both flyer velocity and particle velocity histories. A systematic error analysis shows that the longitudinal sound velocity of aluminum obtained in this experiment is consistent with data from traditional devices, such as gas guns, within the error margin. Finally, we analyze the potential application value of this method in laser technology as well as high-pressure dynamic responses of materials, and conclude the current shortcomings and possible improvements of this method.

MEMS Fabry-Perot sensor for accurate high pressure measurement up to 10 MPa.

Microelectromechanical system (MEMS) Fabry-Perot fiber-integrated pressure sensor exhibits a compact size, intrinsic safety, and high precision measurement. Here, a MEMS Fabry-Perot interferometer sensor is presented. The sensor is fabricated using a standard microfabrication process with a uniformity of 80%. The sensor enables a pressure measurement range of 0-10 MPa with a full-scale nonlinearity error of 1.44% and a repeatability error of 2.14%. A limit of detection of 1.74 kPa and a pressure resolution of 0.017% are achieved. The comparative experiment is conducted to verify the wavelength tracking method is more robust than cavity length demodulation method in this configuration. Moreover, the temperature drift is alleviated by combining a fiber Bragg grating sensor for compensation in a range of -35-88 °C, which is reduced by 15 times to 2.88 ppm/°C. The proposed sensor has wide potential applications, such as downhole environments and petroleum pipeline pressure monitoring.

A molecular mechanism for how pressure induces interdigitation of phospholipid bilayer membranes

The phase transition from the ripple gel phase to the interdigitated gel phase of bilayers of phosphatidylcholines (PCs) with two saturated long-chain fatty acids under high pressure was investigated by pressure-scanning microscopy, fluorometry, and dynamic light scattering (DLS) measurements. Microscopic observation for giant vesicles (GVs) of distearoyl-PC (DSPC) under high pressure showed that spherical GVs transforms significantly into warped and distorted spherical ones instantaneously at the pressure-induced interdigitation. The fluorescence intensities of amphiphilic probe Prodan and hydrophobic probe Laurdan in the dipalmitoyl-PC (DPPC) bilayer steeply decreased and increased, respectively, at the interdigitation, suggesting that the conformational change of the polar head group of DPPC molecule in the bilayer transiently occurred at the interdigitation. Further, it was found from the high-pressure DLS measurements that the size of the vesicle particles of the DPPC and DSPC transiently increases near the interdigitation pressure, whereas the chemically induced interdigitation by adding ethanol to the DSPC bilayer membrane under atmospheric pressure produce no such change in the particle size. Taking account of the critical packing parameter of the PC molecule, the above experimental results would lead us to the conclusion that the pressure-induced interdigitation is attributable to the increase in repulsive interaction between the polar head groups of the PC molecules resulting from the orientational change of the head group from a parallel alignment to a perpendicular one with respect to the bilayer surface by applying pressure, namely the transient state: it occurs when the repulsive interaction exceeds a threshold value for the balance between the repulsive interaction and the attractive interaction among the hydrophobic acyl chains.

Ambulatory Blood Pressure Monitoring in Children: Single Center Experience

Objective: Ambulatory blood pressure monitoring (ABPM) is the preferred method for diagnosis of hypertension(HT) in children. Here, we aimed to demonstrate the reasons for ABPM application and incidence of HT, white coat and masked HT in our cohort besides the evaluation of dipping status, biochemical and radiological parameters between the patients with normotension, elevated blood pressure(EBP) and HT. Material and Methods: Twenty-four hour ABPM results of children followed at department of pediatric nephrology and whose office blood pressure measurements revealed HT or EBP and ABPM records of normotensive patients having chronic kidney disease or renal anomalies were evaluated retrospectively. Twenty-four hour ABPM SD score ≥1.96 defined HT while the value between 1.64 and 1.95 indicated EBP. In addition to assessment of blood pressure loads and nocturnal dipping; age, gender, body mass index(BMI), proteinuria, kidney function tests and ultrasound of urinary system were also assessed. Results: Although ABPM was applied to total of 244 patients, 189 of them were included in the study. High casual blood pressure measurements in 108 (57.1%) asymptomatic patients constituted the major group for ABPM application. Total of 57 patients (30.2%) were normotensive, 18 (9.5%) with EBP and 114 (60.3%) were hypertensive. No difference was found in regards of BMI, proteinuria, serum creatinine levels and sonographic results between the groups. Patients with HT and EBP had significantly lower nocturnal dip than normotensive group (p<0.001). However there was no difference in number of patients with inadequate nocturnal fall in all three groups. Conclusion: ABPM should be preferred for definitive diagnosis of HT in childhood. Patients with inadequate nocturnal fall should be evaluated carefully and followed-up regularly as it had been implicated in the development of cardiovascular disease.

Unconventional charge density wave in a kagome lattice antiferromagnet FeGe

FeGe is a kagome material that exhibits both charge density wave (CDW) order and magnetic order. The CDW order is developed deep inside the A-type antiferromagnetic phase in FeGe, providing a unique platform to investigate the interplay between CDW and magnetism. However, the driving mechanism of the CDW phase remains controversial. In this work, we performed high-pressure electrical transport and x-ray diffraction measurements combined with density-functional theory calculations to investigate the evolution of the CDW of FeGe under pressure. In contrast to conventional CDW materials, the CDW transition temperature of FeGe increases with increasing pressure, indicating the unconventional mechanism of CDW in this material. More interestingly, another possible CDW with a 3×3×6 superlattice emerges above 20 GPa, which may be explained by the calculated metastable CDW states under high pressure. These observations exclude the possibility of Van Hove singularities nesting as a CDW driving force. Our results unveil versatile CDW states and broaden the study of intertwined electronic states in the magnetic kagome metal FeGe. Published by the American Physical Society 2024

Performance Study of F-P Pressure Sensor Based on Three-Wavelength Demodulation: High-Temperature, High-Pressure, and High-Dynamic Measurements.

F-P (Fabry-Perot) pressure sensors have a wide range of potential applications in high-temperature, high-pressure, and high-dynamic environments. However, existing demodulation methods commonly rely on spectrometers, which limits their application to high-frequency pressure signal acquisition. To solve this problem, this study developed a self-compensated, three-wavelength demodulation system composite with an F-P pressure sensor and a thermocouple to construct a comprehensive sensing system. The system produces accurate pressure measurements in high-temperature, high-pressure, and high-dynamic environments. In static testing at room temperature, the sensing system shows excellent linearity, and the pressure sensitivity is 158.48 nm/MPa. In high-temperature testing, the sensing system maintains high linearity in the range of 100 °C to 700 °C, with a maximum pressure-indication error of about 0.13 MPa (0~5 MPa). In dynamic testing, the sensor exhibits good response characteristics at 1000 Hz and 5000 Hz sinusoidal pressure frequencies, with a signal-to-noise ratio (SNR) greater than 37 dB and 45 dB, respectively. These results indicate that the sensing system proposed in this study has significant competitive advantages in the field of high-temperature, high-speed, and high-precision pressure measurements and provides an important experimental basis and theoretical support for technological progress in related fields.

Pressure Induced Nonmonotonic Evolution of Superconductivity in 6R-TaS_{2} with a Natural Bulk Van der Waals Heterostructure.

The natural bulk Van der Waals heterostructure compound 6R-TaS_{2} consists of alternate stacking 1T- and 1H-TaS_{2} monolayers, creating a unique system that incorporates charge-density-wave (CDW) order and superconductivity (SC) in distinct monolayers. Here, after confirming that the 2D nature of the lattice is preserved up to 8GPa in 6R-TaS_{2}, we documented an unusual evolution of CDW and SC by conducting high-pressure electronic transport measurements. Upon compression, we observe a gradual suppression of CDW within the 1T layers, while the SC exhibits a dome-shaped behavior that terminates at a critical pressure P_{c} around 2.9GPa. By taking account of the fact that the substantial suppression of SC is concomitant with the complete collapse of CDW order at P_{c}, we argue that the 6R-TaS_{2} behaves like a stack of Josephson junctions and thus the suppressed superconductivity can be attributed to the weakening of Josephson coupling associated with the presence of CDW fluctuations in the 1T layers. Furthermore, the SC reversely enhances above P_{c}, implying the development of emergent superconductivity in the 1T layers after the melting of T-layer CDW orders. These results show that the 6R-TaS_{2} not only provides a promising platform to explore emergent phenomena but also serves as a model system to study the complex interactions between competing electronic states.

Pressure tuning of superconductivity in TiN thin films

Titanium nitride (TiN) thin films are used for the fabrication of superconducting devices due to their chemical stability against oxidization and high quality at interfaces. The high-pressure technique serves as a useful tool to understand the mechanical and electrical properties of materials, which is crucial for practical applications. However, high-pressure transport measurements of thin films are extremely difficult due to the limited sample space of high-pressure cells and the fragility of thin films. Here, we successfully carried out high-pressure electrical transport and Raman measurements on TiN films up to ∼50 GPa. The superconducting transition temperature gradually decreases with increasing pressure, which can be attributed to the decrease of electron -phonon coupling and is consistent with our first-principles calculations. In addition, the coexistence of a symmetry-enforced Dirac nodal chain and a nodal box is revealed by our calculations in TiN. Our work provides a promising way to study the physical properties of thin films at high pressure, which would broaden the high-pressure research field.

Design and Optimization of a Silicon-Based Electrokinetic Microchip for Sensitive Detection of Small Extracellular Vesicles.

Detection of analytes using streaming current has previously been explored using both experimental approaches and theoretical analyses of such data. However, further developments are needed for establishing a viable microchip that can be exploited to deliver a sensitive, robust, and scalable biosensor device. In this study, we demonstrated the fabrication of such a device on silicon wafer using a scalable silicon microfabrication technology followed by characterization and optimization of this sensor for detection of small extracellular vesicles (sEVs) with sizes in the range of 30 to 200 nm, as determined by nanoparticle tracking analyses. We showed that the sensitivity of the devices, assessed by a common protein-ligand pair and sEVs, significantly outperforms previous approaches using the same principle. Two versions of the microchips, denoted as enclosed and removable-top microchips, were developed and compared, aiming to discern the importance of high-pressure measurement versus easier and better surface preparation capacity. A custom-built chip manifold allowing easy interfacing with standard microfluidic connections was also constructed. By investigating different electrical, fluidic, morphological, and fluorescence measurements, we show that while the enclosed microchip with its robust glass-silicon bonding can withstand higher pressure and thus generate higher streaming current, the removable-top configuration offers several practical benefits, including easy surface preparation, uniform probe conjugation, and improvement in the limit of detection (LoD). We further compared two common surface functionalization strategies and showed that the developed microchip can achieve both high sensitivity for membrane protein profiling and low LoD for detection of sEV detection. At the optimum working condition, we demonstrated that the microchip could detect sEVs reaching an LoD of 104 sEVs/mL (when captured by membrane-sensing peptide (MSP) probes), which is among the lowest in the so far reported microchip-based methods.

High-Pressure Induced Continuous Structural Evolution of Kagome Antiferromagnet MgMn3(OH)6Cl2: A Structural Analogue to Quantum Spin Liquid Herbertsmithite.

MgMn3(OH)6Cl2 serves readily as the classical Heisenberg kagome antiferromagnet lattice spin frustration material, due to its similarity to herbertsmithite in composition and crystal structure. In this work, nanosheets of MgMn3(OH)6Cl2 are synthesized through a solid-phase reaction. Low-temperature magnetic measurements revealed two antiferromagnetic transitions, occurring at ∼8 and 55 K, respectively. Utilizing high-pressure synchrotron radiation X-ray diffraction techniques, the topological structural evolution of MgMn3(OH)6Cl2 under pressures up to 24.8 GPa was investigated. The sample undergoes a second-order structural phase transition from the rhombohedral phase to the monoclinic phase at pressures exceeding 7.8 GPa. Accompanying the disappearance of the Fano-like line shape in the high-pressure Raman spectra were the emergence of new Raman active modes and discontinuities in the variations of Raman shifts in the high-frequency region. The phase transition to a structure with lower symmetry was attributed to the pressure-induced enhancement of cooperative Jahn-Teller distortion, which is caused by the mutual substitution of Mn2+ ions from the kagome layer and Mg2+ ions from the triangular interlayer. High-pressure ultraviolet-visible absorption measurements support the structural evolution. This research provides a robust experimental approach and physical insights for further exploration of classical geometrical frustration materials with kagome lattice.

Development of Ti-Zr-Mn based AB2 type metal hydrides alloys for an 865 bar two-stage hydrogen compressor

This study reports the development of a new Ti-Zr-Mn-based AB2 type hydrogen storage alloys for a two-stage metal hydride hydrogen compressor (MHHC). The hydrogen storage alloys are designed to compress hydrogen from 35 to 865 bar within a temperature difference of 115 °C. High-pressure PCT measurements up to 700 bar were carried out to test the performance of the alloys. The alloys' hysteresis and the plateau slope were reduced by optimizing the composition. The introduction of fugacity correction into the Van't hoff equation reduces the deviation between calculation and actual pressure to 24 bar at a pressure above 350 bar. A precise relation between the Ti/Zr ratio and the desorption pressure is described and helps make a correct design of the alloy composition. The designed alloy shows looses less than 1% of the capacity over 3000 full cycles. The desorption plateau pressure of the alloy is constant within 92% during the whole cycling process. A 2 stages compressor working with two types of alloys offers compression with a temperature range between -20 and 95 °C for the refueling hydrogen vehicles up to 865 bar.

Two-capillary viscometer for temperatures and pressures relevant to CO2 capture, transport, and storage—operation and improved analysis at high pressure

High-pressure viscosity measurements are crucial for understanding CO2 transport and storage because CO2 is often transported as a supercritical fluid, at a high pressure and temperature above its critical point. In this study, we extended the operational range of our new two-capillary viscometer to handle pressures up to 20 MPa, focusing on the behaviour of CO2 at temperatures around 300 K. The analysis model is based on the low-pressure principle, which relied on virial descriptions of density and viscosity, proved inadequate under these conditions. Therefore, we introduced a modified hydrodynamic model as a function of density that is suitable for viscosity measurements at high pressure and liquid states. The modified model bypasses the need for a density virial correction. We conducted initial viscosity tests on pure CO2 at five isotherms: 280.01 K, 298.15 K, 300.01 K, 323.15 K, and 348.15 K to validate the performance of the new two capillary viscometer and the modified model at high pressures. The experimental viscosities agreed with the model predictions and comparable within the estimated uncertainty of the data. In addition, we thoroughly explained the calibrations and the analysis of uncertainty estimation. The uncertainty analysis showed a maximum extended combined uncertainty of 1.3% (k = 2) within all thermodynamic states—gas, liquid, and close to the critical region.