Effect Of High Pressure Research Articles

Combined Effect of High Hydrostatic Pressure and Proteolytic Fraction P1G10 from Vasconcellea cundinamarcensis Latex against Botrytis cinerea in Grape Juice.

The effect of high hydrostatic pressure (HHP) and the proteolytic fraction P1G10 from papaya latex was studied to find out whether a synergy exists in the growth inhibition of Botrytis cinerea in grape juice, contributing to the improvement of conservation techniques and extending the shelf life and quality of food products. Grape juice (GJ) diluted to 16 °Brix with a water activity (aw) of 0.980 was prepared from a concentrated GJ and used in this study. Results indicated a 92% growth inhibition of B. cinerea when exposed to 1 mg/mL of P1G10 and 250 MPa/4 min of pressure treatment. The proximate composition and antioxidant compounds present in the GJ were not significantly affected after the treatments. Eight phenolic compounds and two flavonoids in GJ were identified and quantified, with values fluctuating between 12.77 ± 0.51 and 240.40 ± 20.9 mg/L in the control sample (0.1 MPa). The phenolic compounds showed a significant decrease after the applied treatments, with the HHP sample having a content of 65.4 ± 6.9 mg GAE/100 mL GJ. In conclusion, a synergistic effect at moderate HHP of 250 MPa/4 min with the addition of P1G10 was observed, and the successful development of a stable and acceptable GJ product was possible.

Kinetics of the Diels–Alder Reaction of 2,5-Dimethylfuran with N-Phenylmaleimide: High Hydrostatic Pressure, Temperature, and Solvent Effects

Kinetics of the Diels–Alder Reaction of 2,5-Dimethylfuran with N-Phenylmaleimide: High Hydrostatic Pressure, Temperature, and Solvent Effects

Effects of a sidestream concentrated oxygen supply system on the membrane filtration performance of a high-loaded membrane bioreactor

To investigate the influence of high-pressure and shear effects introduced by a concentrated oxygen supply system on the membrane filtration performance, a laboratory-scale membrane bioreactor (MBR) fed artificial municipal wastewater was operated continuously for 80 days in four phases equipped with different aerations systems: (P1) bubble diffusers (days 0–40), (P2) concentrated oxygen supply system, the supersaturated dissolved oxygen (SDOX) (days 41–56), (P3) bubble diffusers (days 57–74), and (P4) SDOX (days 75–80). Various sludge physical-chemical parameters, visual inspection of the membrane, and permeability evaluations were performed. Results showed that the high-pressure effects contributed to fouling of the membranes compared to the bubble diffuser aeration system. Biofouling by microorganisms appeared to be the main contributor to the cake layer when bubble diffusers were used, while fouling by organic matter seemed to be the main contributor to the cake layer when SDOX was used. Small particle size distribution (PSD) (ranging from 1 to 10 and 1–50 μm in size) fractions are a main parameter affecting the intense fouling of membranes (e.g., formation of a dense and thin cake layer). However, PSD alone cannot explain the worsened membrane fouling tendency. Therefore, it can be assumed that a combination of several factors (which certainly includes PSD) led to the severe membrane fouling caused by the high-pressure and shear.

Correlation between structure and mechanical properties in α-quartz single crystal by nanoindentation, AFM and confocal Raman microscopy

Quartz constitutes a very useful material due to its variety of applications, highlighting solid-state physics for material science with applications for devices and sensors, as piezoelectric for microbalances or oscillators for watches, computers, etc. These applications are very sensible to local pressures and stresses, however, there is not much information in the literature about the effect of high local pressures on the structure and their correlation with mechanical properties. In order to provide more information and clarity on this type of stress-structure-mechanical properties correlation, in this work, nanoindentation combined with Raman Confocal microscopy was carried out since it offers a powerful method to obtain information about the structural deformation and mechanical properties produced by high local pressures in α-quartz single crystal. The information obtained by nanoindentation (pile-up, pop-out, hardness and Υoung modulus) has been correlated with the structural data extracted from Raman spectroscopy, concluding that a permanent plastic deformation occurs under the indentation footprint, sharply appearing a new denser phase, which contribution increases with the applied load.

Investigating the effect of temperature, pressure, and inert gas on the flammability range of ethane/oxygen mixtures

The flammability limit is a critical parameter used to evaluate the risk of explosions from flammable gases and design appropriate explosion-proof measures. This study employs a combined approach of theoretical analysis and experimental determination to investigate the impact of temperature, pressure, and inert gas on the FL of ethane/oxygen mixtures in an environment of elevated temperatures and pressures. The findings demonstrate that the flammability range of ethane/oxygen mixtures progressively widens at elevated temperature and pressure conditions. At high pressures, the upper flammability limit (UFL) of ethane displays a quadratic-linear relationship with temperature, with a turning point at 200 °C. The impact of temperature and pressure on explosion risk is primarily achieved through their effect on the UFL. A new inerting capacity of added diluting gas, δ, is defined for inert gas, revealing that the inerting effect of diluting gas is enhanced under the influence of temperature or pressure. However, the inerting effect of nitrogen weakens as the initial pressure increases, while it strengthens as the initial temperature increases. The inerting effect of water vapor in the system of ethane/oxygen/nitrogen is superior to that of nitrogen. The combustion reaction kinetics of ethane and nitrogen near the UFL is influenced by high temperature, high pressure, and water vapor. The coupling effect of high initial temperature and pressure on the inerting effect of the two inert gases is less pronounced than that of single factors.

Effects of high hydrostatic pressure on antimicrobial protein stability and the rheological and shelf-life properties of donkey milk.

The effects of high hydrostatic pressure (HHP) and heat treatments on antimicrobial protein stability and on the physico-chemical, microbiological, rheological and shelf-life properties of donkey milk were investigated. Although heat treatment at 75°C for 2 min resulted in 1.50 log CFU ml-1 microbial inactivation, losses in activities of lysozyme (58%) and lactoferrin (82%) were observed due to whey protein denaturation. By contrast, HHP application at 400 MPa caused lower enzyme activity losses (22 and 37% respectively) whilst maintaining a significant reduction of microbial load (1.80 log CFU ml-1). Color analyses showed that the lightness values of all samples decreased during storage. Higher flow consistency (viscosity) and lower flow behavior indexes were observed in heat-treated samples compared to untreated and HHP-treated ones, which can be explained by advanced protein denaturation during heat-treatment. The results suggest that HHP is a more suitable process than heat treatment for preservation of donkey milk within the conditions studied.

Effects of high hydrostatic pressure (HHP) on the rheological properties of pulp nectarine and the spray drying on the powder properties

Effects of high hydrostatic pressure (HHP) on the rheological properties of pulp nectarine and the spray drying on the powder properties

Stabilizing Effect of High Pore Fluid Pressure on Fault Growth During Drained Deformation

AbstractDilatant hardening is an accepted model for the stabilizing effect of high pore fluid pressure on fault slip and operates when deformation is undrained. To test whether high pore fluid pressure impedes fault propagation under drained conditions, we deformed highly permeable Darley Dale sandstone using strain rates of 10−4 s−1, 10−5 s−1, and 10−6 s−1, respectively. For each strain rate, we compared the inelastic behaviors and faulting styles among rocks deformed under different pore fluid pressures (Pf) (2–180 MPa). The confining pressure (Pc) was attuned to the pore fluid pressure throughout deformation to maintain a constant differential pressure (Pc − Pf) of 10 MPa. In samples deformed at 10−4 s−1 and 10−5 s−1, faulting behaviors were similar regardless of the magnitude of pore fluid pressure. However, when the strain rate was lowered to 10−6 s−1, we observed prolonged stress drops and slower slip velocities in samples deformed under high pore fluid pressures. In samples deformed at 10−6 s−1, we demonstrate that chemically assisted subcritical crack growth played an important role during faulting. A quantitative microstructural analysis revealed that slow faulting at slow strain rates was accompanied by pervasive microcracking and diffuse shear bands, which suggests pervasive subcritical cracking enabled slow faulting under drained conditions at the sample length scale. High pore fluid pressure may have facilitated slow faulting chemically by increasing the rate of subcritical cracking, mechanically via localized dilatant hardening, or both. Our results provide insight into the mechanics of faulting in natural settings where subcritical cracking is prevalent.

On the effect of pellet density on biomass pyrolysis in a pressurized fixed bed reactor

In this work, pellets of different densities but the same particle size were prepared from pine wood. The pellets as well as the raw biomass sample, all in form of cubic blocks whose side was 5 mm, were pyrolysed in a pressurised fixed bed reactor at different temperatures (350 and 500 °C) and pressures (1 and 8 bar) to investigate how variation in biomass density affect the product distribution, tar and gas compositions, and char characteristics. More char and less tar were obtained from pellets of higher density at the same pyrolysis conditions. Chars from the pyrolysis of pellets of higher density contain more oxygen and less amount of crystallite clusters, making them more reactive in combustion tests run by thermogravimetric analysis (TGA). Tars were obtained from higher-density pellets in lower yields and were lighter (smaller molecular weight distribution) than those from less dense pellets. At higher temperatures extensive biomass decomposition forms chars with more crystallite clusters and less oxygen, while a higher char yield with less oxygen was obtained at higher pressures, along with smaller amount of a lighter tar. Higher temperature and pressure tend to produce a less reactive char. Through this systematic work, the similarities as well as some key differences between the effect of higher pressure and greater particle density on pyrolysis behavior have been identified.

Dielectric properties of (FeCoCrMnZn)3O4 high-entropy oxide at high pressure

The emerging high-entropy oxides (HEOs) have been considered promising candidates in numerous applications due to their unique properties. Yet the dielectric properties of HEOs at high pressure remain to be disclosed. In this work, the dielectric properties of (FeCoCrMnZn)3O4 at high pressures up to ∼20 GPa were systematically investigated. Combined with in-situ Raman, XRD, and impedance measurements, it is revealed that high-pressure exhibits a significant impact on the dielectric properties, even without the observed phase transition. The electric resistance, which is dominantly contributed by grain resistance, decreases exponentially with the increase of pressure. On the other hand, the relative permittivity decreases linearly with increasing pressure. In addition, the dielectric relaxation behavior of (FeCoCrMnZn)3O4 at high pressure is revealed. Our results provide the experimental basis for the high-pressure effect on the dielectric properties of (FeCoCrMnZn)3O4 and potential guidance for the design strategy of HEOs under extreme conditions.

High pressure, temperature, and solvent effect on the Diels–Alder cycloaddition reaction between thiobenzophenone and cyclopentadiene

AbstractThe data on high hydrostatic pressure, temperature, and solvent influence on the Diels–Alder reaction rate of thiobenzophenone with cyclopentadiene have been obtained. Activation enthalpies, entropies, volumes, and reaction volumes in several solvents have been determined. The activation entropies and volumes of the Diels–Alder reaction of thiobenzophenone with cyclopentadiene are close to the corresponding activation parameters of Diels–Alder reactions involving dienophiles with C=C and N=N bonds. The rate of thiobenzophenone‐cyclopentadiene reaction did not increase with increasing solvent polarity, which is also characteristic of other Diels–Alder reactions. The reaction of thiobenzophenone with cyclopentadiene is characterized by an “anomalous” ratio of the activation volume to the reaction volume ∆V≠/∆Vr‐n > 1. This can be explained by the less steric hindrances of transition‐state molecules toward the solvent, compared with adduct molecules. The activities of a number of dienophiles with C=C, C=S, and N=N bonds have been compared, and the factors determining their reactivity in Diels–Alder reactions have been established.

Dexmedetomidine ameliorates diabetic cardiomyopathy by inhibiting ferroptosis through the Nrf2/GPX4 pathway

ObjectiveDexmedetomidine (DEX) has been shown to have anti-apoptotic effects in diabetes mellitus, but its role in mitigating diabetic cardiomyopathy (DCM) through ferroptosis regulation is unclear.MethodsAn in vitro DCM model was established using H9C2 cells induced with high glucose (HG) and treated with DEX at varying doses and a nuclear factor erythroid 2-realated factor 2 (Nrf2) specific inhibitor ML385. Cell viability was evaluated using the MTT method after treatment with DEX or mannitol (MAN), and the dosage of DEX used in subsequent experimentation was determined. The effects of HG-induced high osmotic pressure were assessed using MAN as a control. Cell apoptosis was evaluated using flow cytometry. Protein levels of Bcl2, Bax, nuclear Nrf2, and glutathione peroxidase 4 (GPX4) were measured using Western blot. Superoxide dismutase (SOD) activity, malondialdehyde (MDA) levels, Fe2+ concentration and reactive oxygen species (ROS) levels were measured using corresponding kits and dichlorodihydrofluorescein diacetate, respectively.ResultsTreatment with DEX or MAN had no effect on H9C2 cell viability. HG induction reduced H9C2 cell viability, increased cell apoptosis, upregulated levels of Bax, Fe2+, MDA, and ROS, and downregulated Bcl2 protein levels, SOD activity, and protein levels of nuclear Nrf2 and GPX4. DEX inhibited HG-induced H9C2 cell apoptosis, promoted Nrf2 nuclear translocation, and activated the Nrf2/GPX4 pathway. Inhibition of Nrf2 partially reversed the protective effects of DEX against HG-evoked H9C2 cell injury.ConclusionOur findings demonstrate that DEX attenuates HG-induced cardiomyocyte injury by inhibiting ferroptosis through the Nrf2/GPX4 pathway, providing potential therapeutic targets for DCM treatment.

Study on the optimal target distance of self-oscillation pulsed SC-CO2 jet based on resonant effect

The SC-CO2 jet has broad application prospects in drilling engineering, but its promotion and application are limited by the high threshold pressure of coal breaking and system energy consumption. The high pulse pressure and resonance effects of the self-oscillation pulsed SC-CO2 jet can effectively reduce the threshold pressure of coal breaking and significantly improve the coal breaking efficiency. To fully utilize the resonance effect, based on the nozzle structure of the self-oscillation pulsed SC-CO2 jet, two nozzles with different pulse characteristics are used to study the comprehensive effect of pulse frequency and pressure amplitude at different target distances. The large eddy simulation was used to analyze the flow field structure of the jet, and the variation laws of the pulse frequency and pressure amplitude in the axial direction of the flow field were clarified. The effect of the target distance on the impact frequency and impact pressure of the jet was studied by the pulse characteristics test experiment, and the comprehensive effect of pulse characteristics on coal breaking was studied by coal breaking experiments. The results show that the pulse frequency and pulse pressure amplitude of the self-oscillation pulsed SC-CO2 jet do not remain constant in the axial direction of the jet, and they gradually decrease with the increasing target distance. Considering only the pulse frequency cannot maximize the resonance effect, and it is necessary to comprehensively consider the influence of pulse frequency and pressure amplitude on the resonance effect. Using displacement response amplitude to characterize the resonance effect can reflect the comprehensive influence of frequency and amplitude on resonance. When the target distance is small, from 0 mm to 13 mm, the main influencing factor of the displacement response amplitude is the pulse pressure amplitude; when the target distance is large, from 13 mm to 26 mm, the main influencing factor changes to the pulse frequency. In addition, reducing the pulse frequency and increasing the pressure amplitude can effectively improve the displacement response amplitude. Under the conditions of nozzle structure with different pulse characteristics, the transition positions of the main influencing factors of displacement response amplitude are different, and the optimal target distance is also not the same. Both nozzles achieve the best coal breaking effect at the maximum displacement response amplitude, which indicates that the displacement response amplitude can be used as the criterion to judge the optimal target distance. In this paper, the dimensionless optimal target distances of nozzle a and nozzle b are 7 and 9 respectively.

Improved High Temperature Thermoelectric Properties in Misfit Ca3Co4O9 by Thermal Annealing

Ca3Co4O9, a p-type thermoelectric material based on transition-metal oxides, has garnered significant interest due to its potential in thermoelectric applications. Its unique misfit-layered crystal structure contributes to low thermal conductivity and a high Seebeck coefficient, leading to a thermoelectric figure of merit (zT) of ≥1 at 1000 K. Conventionally, it has been believed that thermopower reaches its upper limit above 200 K. However, our thermopower measurements on polycrystalline Ca3Co4O9 samples have revealed an unexpected increase in thermopower above 380 K. In this study, we investigate the effects of high oxygen pressure annealing on Ca3Co4O9 and provide an explanation based on the mixed oxide states of cobalt and carrier hopping. Our results demonstrate that annealing induces modifications in the defect chemistry of Ca3Co4O9, leading to a decrease in electron hopping probability and the emergence of a thermal activation-like behavior in thermopower. These findings carry significant implications for the design and optimization of thermoelectric materials based on misfit cobaltates, opening new avenues for enhanced thermoelectric performance.

Combined effects of high hydrostatic pressure and chemical pre‐treatment on physico‐chemical properties of beef, using FTIR and diffuse reflectance spectroscopy

AbstractHigh pressure processing (HPP) was combined with a previous short chemical treatment to stabilize the color of beef tissue. Beef samples were treated with a solution containing ascorbic acid, sodium chloride, and a very low concentration of sodium nitrite. The effects of pressure levels (0.1–600 MPa) and preservative solution on: (i) color properties based on diffuse reflectance spectroscopy (DRS), which determines the relative concentrations of muscle pigments, (ii) protein denaturation and changes in the secondary structures by DSC and FTIR‐ATR, were determined.At high pressures, the disappearance of DSC peaks due to protein denaturation, a decrease in the proportion of α‐helix and an increase in the percentage of disordered structures, were evidenced. DRS spectra and Kublelka‐Munk theory equations demonstrated that nitrosilmyoglobin was a more stable chromophore, decreasing discoloration of the tissue. These techniques contribute to the knowledge of the physico‐chemical properties of the tissue submitted to combined preservation processes.Practical ApplicationsThere is an increasing demand from consumers for high‐quality beef products, with significant emphasis placed on color and safety attributes. Extending the shelf life by applying high hydrostatic pressure treatment (HHP) improves food safety and will produce a positive impact on both the industry and consumers. HHP is a non‐thermal preservation technology with generally minimal effects on sensory qualities and nutritional content; however, the direct application of this technology on beef leads to the production of a product with an unacceptable pale coloration. Therefore, it must be remarked that a pre‐treatment stage by immersing the pieces in a preservative solution is essential to improve the color of beef products treated by HHP. In this regard, from a technological point of view, it is very important to know the combined effects of both stages (short chemical treatment and high‐pressure) on the quality of beef products.

High pressure effects on magnetic states of elemental holmium

The pressure response of the magnetic and structural properties of elemental holmium was explored by means of neutron powder diffraction in the pressure range up to 8.7 GPa and the temperature range 7 – 290 K. At ambient pressure, below TN = 127 K the incommensurate helical state with a propagation vector q = (0 0 qz) is evidenced. On temperature lowering, the qz value decreases from 0.270c* (at 125 K) to 5/26c* at TL = 20 K. Below the lock-in transition temperature TL, a commensurate cone structure is formed due to canting of magnetic moments towards the c axis. Upon lattice compression, a gradual suppression of the low temperature cone structure was found and just a helical state was observed above 4 GPa. This state is incommensurate in the temperature range TL < T < TN and becomes commensurate below TL. At T = 7 K, the qz component evolves towards ¼ c* value at 8.7 GPa. The Néel temperature decreases to 108 K with a pressure increase up to 8.7 GPa with a pressure coefficient dTN/dP ≈ −2.2 K/GPa, while the lock-in transition temperature exhibits opposite behavior and grows up to about 50 K with a coefficient of dTL/dP ≈ 3.4 K/GPa. The magnetic P-T phase diagram of Ho is constructed. The compression of Ho lattice at T = 7 K is nearly isotropic, as found from about the same compressibilities of the a and c axes.

Botrytis cinerea induced phytonutrient degradation of strawberry puree: effects of combined preservation approaches with high hydrostatic pressure and synthetic or natural antifungal additives

ABSTRACT Fungi can thrive in strawberries, mainly Botrytis cinerea, which causes relevant fruit losses. Moreover, thermal preservation results in phytonutrient losses. This study evaluated the effects of high hydrostatic pressure (HHP, 0, 400, and 600 MPa/5 min) processing with potassium sorbate (PS) or avocado seed acetogenins (ASA) on the nutritional, microbiological, and physicochemical properties of strawberry puree inoculated with Botrytis cinerea. Sole inoculation reduced L-ascorbic acid (L-AA, 84%) and total ascorbic acid (TAA, 38%). Instrumental color Hue angles were reduced from 35.0 to 29.4°, likewise the contents of pelargonidin−3-glucoside (25%) and ellagic acid (38%). Both HHP-PS treated samples contained no viable conidia and high TAA; the no-preservative and HHP-ASA (661 µg/mL, 400 MPa/5 min) purees contained high TAA but had viable conidia, which can induce further phytonutrient losses. HHP and antifungal additives maintained ellagic acid, increased pelargonidin−3-glucoside contents, and inactivated conidia, strengthening the value of combined non-thermal technologies for the preservation of strawberry puree

In the prevention of dementia, the focus should be on early and consistent treatment of hypertension.

The brain is among the target organs of hypertension. Patients with hypertension have a higher risk of developing stroke as well as experiencing a decline in cognitive functions and dementia. Changes in the white matter and atrophy of the grey matter of the brain induced by high blood pressure develop insidiously since the onset of hypertension, even in young individuals. The effect of high blood pressure on the vessel wall cumulates in time; therefore, hypertension in younger people implies an increased risk of dementia in older age. Hypertension in young age cannot be considered a benign condition. Hypertension in middle age increases the risk of dementia by 61 %. Consistent and early hypertension control can reverse the adverse development towards dementia and lack of self-sufficiency in the patient. Data comparing individual antihypertensive drugs in terms of preventing dementia are scarce. However, renin angiotensin system blockers have been found to protect against Alzheimer's disease more than other classes of antihypertensive drugs. To achieve rapid and effective hypertension control, a combination of antihypertensive drugs is usually required. Using a fixed-dose triple combination of perindopril, indapamide, and amlodipine, blood pressure targets of &lt; 130/80 mm Hg can be achieved within three months in 93 % of patients.

Effect of High Hydrostatic Pressure and Thermal Processing on the Shelf Life and Quality Attributes of Apple-Kiwi-Carrot Puree Blend

The effects of high hydrostatic pressure (HHP) (400 MPa/2 min and 500 MPa/2 min) and thermal processing (TP) (90°C/2 min) on the microorganisms, nutrition, color, endogenous enzyme activities, antioxidant capacity, and rheological properties of blended apple-kiwi-carrot puree were comprehensively evaluated after processing and during storage at 4°C. Results showed the microbiological shelf life of the HHP or TP products was at least 24 days. TP inactivated polyphenol oxidase activity more effectively, retaining more polyphenols in samples during storage, whereas HHP treatments were more beneficial for the preservation of ascorbic acid, total carotenoids, β-carotene, and antioxidant capacity. During storage, there was no significant difference in PME activity among all treated samples, but particle size distribution and viscoelasticity tests demonstrated that the 400 MPa treated samples were more stable in their textures. Moreover, the principal component analysis (PCA) intuitively revealed that the overall sensory and nutritional attributes of the HHP-treated samples were closer to the fresh product. These results demonstrated that HHP could be a better choice than TP for use in the production of high-quality puree blends.

Investigation of the upper flammability limit of ethylene/propane mixtures in air at high temperatures and pressures

The upper flammability limit (UFL) of ethylene/propane mixtures was investigated using a self-built 20 L spherical explosion characteristic experimental device at initial temperatures ranging from 20 to 200 °C and initial pressures from 0.1 to 1.5 MPa. The effects of temperature, pressure, and ethylene blending ratio on the UFL were analyzed, and a mathematical function of the UFL as a function of temperature and pressure parameters was derived. The results show that the UFL of ethylene and propane displayed an almost linear incline as the temperature rose. Conversely, the ascending pattern of the UFL diminished for both gases as the pressure increased. At elevated temperatures and pressures, both propane and ethylene-propane mixtures demonstrated a bilinear correlation with temperature. Moreover, the impact of increasing pressure on the UFL of blended fuels became less pronounced as the proportion of ethylene in the blend increased. Furthermore, the synergistic effect of temperature and pressure on the UFL was much greater than the sum of the effects of the two individually. Thus, the explosion risk of ethylene/propane mixtures is elevated under the synergistic effect of high temperature and high pressure, and the risk is further increased with an increase in the ethylene blending ratio.