Changes In Pressure Research Articles

Cm-p5, a molluscan-derived antifungal peptide exerts its activity by a membrane surface covering in a non-penetrating mode

Amidst the health crisis caused by the rise of multi-resistant pathogenic microorganisms, Antimicrobial Peptides (AMPs) have emerged as a potential alternative to traditional antibiotics. In this sense, Cm-p5 is an AMP with fungistatic activity against the yeast Candida albicans. Its antimicrobial activity and selectivity have been well characterized; however, the mechanism of action is still unknown. This study used biophysical approaches to gain insight into how this peptide exerts its activity. Stability and fluidity of lipid membrane were explored by liposome leakage and Laurdan generalized polarization (GP) respectively, suggesting that Cm-p5 does not perturb lipid membranes even at very high concentrations (≥100µm.L-1). Likewise, no depolarizing action was observed using 3,3'-propil-2,2'-thyodicarbocianine, a potential membrane fluorescent reporter, with C. albicans cells or the corresponding liposome models. Changes in liposome size were analyzed by Dynamic Light Scattering (DLS) data, indicating that Cm-p5 covers the vesicular surface slightly increasing liposome hydrodynamic size, without liposome rupture. These results were further corroborated with Langmuir monolayer isotherms, where no significant changes in lateral pressure or area per lipid were detected, indicating little or no insertion. Finally, data obtained from molecular dynamics simulations aligned with in vitro observations, whereby Cm-p5 slightly interacted with the fungal membrane model surface without causing significant perturbation. These results suggest Cm-p5 is not a pore-forming anti-fungal peptide and that other mechanisms of action on the membrane as some limitation of fungal nutrition or receptor-dependent transduction for depressing growth development should be explored.

Study on the pullout bearing characteristics of bio-inspired root piles in coral sand foundation under different root buried depths

Root foundation is a new type of bio-inspired foundation, which has a broad application prospect in the development and construction of China's South China Sea area due to its good bearing characteristics such as pullout bearing capacity. The effect of root buried depth on the uplift bearing characteristics of root piles is analyzed through the model test of uplift bearing of root piles with different root buried depths in coral sand foundation. The results show that increasing the root buried depth can improve the ability of the root pile to control the uplift displacement, and there exists an optimal buried depth or range of buried depths that can effectively improve the pile foundation's uplift bearing capacity and control the ultimate displacement. The attenuation of axial force at the root is in the form of a step; with the increase of root buried depth, the maximum value of lateral friction resistance develops from the lower part of the pile body without root to the upper part of the pile body without root. The range of the bearing ratio of the root section of the pile with root buried depth of 260mm, 340mm and 420mm is 12.33%-15.68%, 9.98%-17.82% and 7.61%-21.65%, respectively; the smaller the root buried depth is, the higher is the ratio of the bearing ratio of the root section at the beginning of loading, and the bigger the root buried depth is, the bigger is the ratio of the root's final bearing ratio. The change of soil pressure around the pile increases and then decreases, and the densest point of soil compacting moves upward with the increase of root buried depth. The research results provide scientific basis for the design of root pile buried depth and root arrangement in actual projects.

Effect of the magnitude of abrupt change in sound pressure on the magnitude and phase synchrony of 40-Hz auditory steady state response

A periodic sound with a fixed inter-stimulus interval elicits an auditory steady-state response (ASSR). An abrupt change in a continuous sound is known to affect the brain’s ongoing neural oscillatory activity, but the underlying mechanism has not been fully clarified. We investigated whether and how an abrupt change in sound intensity affects the ASSR. The control stimulus was a train of 1-ms clicks with a sound pressure level (SPL) of 70 dB at 40 Hz for 1000 ms. In addition to the control stimulus, we applied six stimuli with changes consisting of a 500-ms train at 70 dB followed by a 500-ms similar train with louder clicks of 75, 80, or 85 dB or weaker clicks of 55, 60, or 65 dB. We obtained the magnetoencephalographic responses from 15 healthy subjects while presenting the seven stimuli randomly. The two-dipole model obtained for the 40-Hz ASSR in the control condition was applied to all of the stimulus conditions for each subject, and then the time–frequency analysis was conducted. We observed that both the amplitude and the inter-trial phase coherence of the 40-Hz ASSR transiently decreased and returned to the steady state after the change onset, i.e., the desynchronization of 40-Hz ASSR. The degree of desynchronization depended on the magnitude of the change regardless of whether the sound intensity increased or decreased, which might be a novel neurophysiological index of cerebral response driven by a change in the sensory environment.

The investigations of asperity peaks and surface roughness on transient squeeze elastohydrodynamic lubrication

Abstract The effects of asperity peak contact pressure and surface roughness (SRN) on pure squeeze elastohydrodynamic lubrication (EHL) motion of circular contacts are investigated for fixed load by using Gauss-Seidel iteration method (GSIM) and finite difference method (FDM). The transient pressure, asperity peak contact pressure, elastic deformation, and film thickness during the pure squeeze process under distinct operating conditions in EHL regime are studied. The results indicate that the differences of the pressure and film thickness between SRNEHL model and EHL model are apparent in final stage due to elastic asperity peak contact. The asperity peak contact pressure will affect hydrodynamic pressure for fixed load, so the hydrodynamic pressure with roughness surface is smaller than that without roughness surface especially around the Hertzian contact (X=1) edge. These phenomena result in different changes in total pressure in different areas. For the contact region, the film thickness of smooth type (ST) is greater than those of circular roughness type (CRT), but this phenomenon reverses near X=1. The larger the C value, the earlier the asperity peak contact effect. Therefore, the greater the C values, the greater the asperity peak contact pressure, and the smaller the hydrodynamic pressure. The asperity peak contact effect significant changes many phenomena at contact region in squeezing final stage.

213 - Hypopressive exercises do not cause transient changes in intra-abdominal pressure in females: an observational cohort study

213 - Hypopressive exercises do not cause transient changes in intra-abdominal pressure in females: an observational cohort study

The influence of heart rate on the relationship between pulse transit time and systolic blood pressure

Pulse transit time (PTT) is a popular indicator of blood pressure (BP) changes. However, the relationship between PTT and BP is somehow individual dependent, resulting in the inaccuracy of PTT-based BP estimation. Confounding factors, e.g., heart rate (HR), of PTT and BP could be the primary cause. In this study we attempt to explore the impact of HR as a window to look at the influence of confounding factors on the relationship between PTT and BP. We investigated the relationship between PTT and systolic BP (SBP) at different HR levels by introducing the heterogeneous treatment effects (HTE) as a quantitative indicator. Compared to the average HR calculated using traditional indicators (e. g. regression coefficient, correlation coefficient), the HTE calculation method can compute the relationship between PTT and SBP at different HR levels, and reduce the influence of confounding factors. We analyzed the HTE of PTT and SBP of 47 subjects who are resting healthy young people with varying levels of HR. The results showed that the strength of the HTE of PTT and SBP varied with HR, indicating that the strength of the causal relationship between PTT and SBP is subject to HR levels. Whereas the correlation between SBP and PTT was individual dependent; either the strength or the direction of the correlation can vary with HR. We further investigated the group in which PTT and SBP exhibited a negative correlation, and found that about 50% of the subjects showed enhanced strength of HTE in with an increase in HR and the remaining showed the opposite. This study means that HR needs to be considered when PTT is used as an indicator of SBP.

Comparative Study Of Standard Drug Dose Mixture Versus Fentanyl In Attenuating Stress Response During Laryngoscopy And Tracheal Intubation In Neurosurgery: A Prospective Observational Study

Background: Opioid-free anesthesia (OFA) is gaining prominence, particularly in neurosurgery, due to its potential to minimize opioid-related complications such as postoperative nausea and vomiting (PONV) and shivering. This Prospective observational study aims to compare the efficacy of a standard drug dose mixture comprising intravenous magnesium sulphate, lignocaine, paracetamol, and tramadol with fentanyl in attenuating the hemodynamic stress response during laryngoscopy and tracheal intubation. Methods: Sixty neurosurgical patients, aged 18 to 60 years, undergoing cervical or lumbar discectomies under general anesthesia in our institute were divided into two groups. One group received the standard drug dose mixture, and the other received fentanyl. Hemodynamic parameters, including pulse rate, blood pressure, oxygen saturation (SpO2), and electrocardiogram (ECG) changes, were recorded at baseline, during intubation, and at one- minute intervals for five minutes post-intubation. Results: Both groups demonstrated stable hemodynamics with no significant differences in pulse rate or blood pressure. No ECG abnormalities were observed, and SpO2 remained above 96% in all patients. Additionally, the standard drug dose mixture group showed a reduced incidence of PONV and shivering compared to the fentanyl group. Conclusion: The standard drug dose mixture provides a safe and effective alternative to fentanyl for attenuating the hemodynamic stress response during laryngoscopy and tracheal intubation, with fewer side effects. Further randomized controlled trials are recommended to confirm these findings and explore the benefits of opioid-free anesthesia in various surgical procedures.

Multi-physics coupling numerical simulation of variable porosity in reactive melt infiltration process

Abstract The hypersonic craft necessitates significant advancements in thermal shielding to safeguard against the extreme aero-thermal environments encountered during flight at hypersonic speeds in near space or upon reentry from space. Carbon fiber-reinforced ceramic matrix composites (FRCMCs) have attracted increasingly interesting attention as advanced structural materials for application in thermal protection. The reactive melt infiltration (RMI) process is preferred for the preparation of FRCMCs because of its low cost and short processing time. However, the RMI process includes the complex interplay of melt flow, reaction dynamics, and thermal fields, with existing models failing to accurately predict these processes due to their uncoupled nature and neglect of pore structure changes. This study introduces a coupled model that integrates mass transfer flow, chemical reaction, and heat transfer, incorporating variable pore structures to more accurately evaluate the RMI process. This approach allows for a comprehensive assessment of internal pressure, temperature, and porosity changes during silicon infiltration into porous media, marking an improvement over the previous model. The model has been validated for use in predicting the exotherm of RMI processes. In conclusion, this coupled model presents a promising avenue for enhancing the fabrication of FRCMCs, either considering the melt infiltration from multiple locations in the RMI process or adjusting the pore structure at the infiltration location to larger pores.

A study on the microscopic mechanism of oil displacement in an adaptive profile control and plugging composite displacement system

This study employed a self-designed microfluidic chip with visualized oil displacement technology and indoor core flooding experiments to reveal the microscopic plugging and adjustment mechanisms. Additionally, it involved the microscopic oil displacement mechanism of an adaptive plugging and flooding composite system containing PPG (preformed particle gel) particles and two blended surfactants.The results indicated that microfluidic imaging captured the dynamic seepage characteristics of PPG particles after swelling, which involved plugging, deformation, and passage through a 0.3 mm throat in a series of pores, achieving adaptive plugging between the size of PPG particles and the pore size. The plugging mechanism of PPG particles involves blocking larger parallel pores, increasing the displacement velocity in smaller pores, and dynamically adjusting the plugging to achieve simultaneous displacement in the high- and low-permeability layers. The displacement mechanism of PPG particles in the simulated pores includes reducing seepage radius, expanding sweep area, and repeatedly overcoming capillary forces.The pressure variation data along the length of different permeability long cores demonstrated that the pressure drop within the first third of the injection end increases with an increase in permeability. The pressure change curve illustrates the migration characteristics of PPG particles in the pore throats, characterized by “accumulation and plugging–pressure increase–deformation and migration.”After injecting the adaptive plugging and flooding composite system following polymer flooding, the flow fraction in the high-permeability layers decreased to 25.65 %, whereas that in the low-permeability layers increased to 74.56 %. The difference in the water flooding pressure before and after implementing the adaptive plugging and flooding system reached a factor of 29, and the oil recovery rate improved by 5.55 % compared to a weak alkaline ternary composite system.The adaptive plugging and flooding composite system demonstrated a synergistic effect in expanding swept volume, blocking preferential flow channels, and enhancing oil displacement efficiency. It achieved the effects of simultaneous plugging and flooding, dynamic plugging adjustment, and synchronized displacement in the high- and low-permeability layers, thereby significantly improving the mobilization of residual oil after polymer flooding.

Numerical Simulation Study of an Artificial Percolation Riverbed and Its Hydraulic Characteristics under Different Reynolds Numbers

The direct extraction of clear water from a sandy river is a difficult task and can only be achieved through specific engineering measures. This paper proposes an artificial percolation riverbed structure for extracting clean water from sandy rivers, using a numerical simulation to study the flow field distribution characteristics of the structure under clean water conditions. The main conclusions are as follows: When the percolation vortex tube opening rate is 1.4%, the vortex tube with or without opening the percolation hole has little influence on the distribution characteristics of the flow field in the artificial riverbed, and the purpose of water extraction can be achieved while constructing a helical flow field. The axial flow velocity and circumferential flow velocity of the vortex tube cross-section under different Reynolds numbers show the distribution of a low-flow velocity close to the center of the vortex tube, and a high-flow velocity close to the vortex tube side-wall area. The average axial flow velocity and average circumferential flow velocity of the vortex tube show a trend of increasing and then decreasing distribution along the axial axis of the vortex tube in the direction of the sediment transport flume. The mean axial flow velocity of the vortex tube along the axis of the vortex tube toward the sediment transport flume and the mean circumferential flow velocity both show a distribution trend of increasing and then decreasing. At the junction of the vortex tube and the sediment transport flume, there are obvious pressure changes, and the pressure changes drastically under the same horizontal line. Along the direction of the bottom line of the vortex tube, the pressure at the vortex tube is obviously greater than that at the sediment transport flume. The vortex of the artificial percolation riverbed is mainly concentrated in the vicinity of the vortex tube, and the maximum value of the vortex intensity generally occurs at the junction of the vortex tube and the sediment transport flume. With the increase in the Reynolds number, the vortex intensity has an overall increasing trend, and the distribution of the vortex is more complex. This study helps to elucidate the distribution characteristics of the flow field in the artificial percolation riverbed, and it provides a reference basis for the future study of the flow field of artificial percolation riverbeds of sandy rivers.

Response of Water Temperature to Wind Speed and Air Temperature in Lake Laut Tawar, Aceh Province, Indonesia

Changes in water temperature impact the dynamics of lake ecosystems. Changing climate factors, including wind speed and air temperature, influence the water temperature of lakes. This research aims to analyze the response of water temperature to wind speed and air temperature in Lake Laut Tawar. Observations were conducted from August to September 2023, with a sampling frequency of every two weeks. The results revealed that water temperature, wind speed, and air temperature in Lake Laut Tawar fluctuated according to the presence of light, namely day and night factors. Variations in sunlight intensity lead to hourly fluctuations in air temperatures, while wind speeds vary hourly due to changes in air pressure, consequently resulting in hourly variations in water temperature as well. During daylight hours, air temperature surpasses water temperature, whereas during nighttime hours, water temperature exceeds air temperature. Heat transfer from the air to the water contributes to an increase in water temperature, while the release of heat energy from the surface water into the air leads to a decrease in water temperature. Changes in the water temperature of Lake Laut Tawar are primarily influenced by changes in wind speed and air temperature by 80 percent simultaneously. However, while air temperature showed a partial response, wind speed did not exhibit a significant response. The relationship between these variables can be expressed through a mathematical model Tw = 0.356 Ta + 0.025 W + 15.674, where Tw is water temperature (°C), Ta is air temperature (°C), and W is wind speed (km/minute). Another factor that influences the water temperature of Lake Laut Tawar is the inlet water temperature, which was not observed in this research.

Accuracy of the geometric shape of the hole in the longitudinal section during honing

The wide application of honing as a finishing treatment of internal cylindrical surfaces for cylinder-piston systems, used in some structures, is caused by high accuracy measured in tenths of a micrometer, and high productivity of the process. The most important indicator of reliable operation of cylinder-piston systems are high requirements for the geometric accuracy of holes. Due to the lack of sufficient theoretical justification for the selection of honing parameters ensuring the accuracy of the geometric shape of the hole in the longitudinal section, the authors proposed a model for the formation of errors in the geometric shape of the hole. The model is built on the kinematic characteristics of the process including the ratio of the honing stone dimensions, the length of the hole, the stroke of the honing head, the ratio of the speeds of translational and rotational movements, and the force action in the processing zone, which changed due to the presence of an overrun of the honing stone. To obtain analytical dependencies ensuring the minimisation of form deviations, the conditions for stock removal for the points of the machined surface were considered, the value of which was taken proportional to the path of movement, and the pressure value. For this purpose, graphs of the distribution functions of displacements and pressure changes were constructed depending on the coordinate of the point location on the generating line of the hole being machined. Using the obtained analytical dependencies, the potential occurrence of a shape error in the form of a saddle shape was found, the dominant factor influencing the value of which is the value of the honing stone overrun. At the same time, it was identified that the ratio of the speeds of translational and rotational movements has an insignificant effect on the violation of the form in the longitudinal section.

Effectiveness of Respiratory Muscle Training in Pompe Disease: A Systematic Review and Meta-Analysis.

Background: Pompe disease is a rare metabolic myopathy caused by the lack or deficiency of the lysosomal acid alpha-glucosidase, resulting in skeletal muscle weakness and cardiomyopathy. The disease varies by onset age and genetic mutations and is categorized into infantile-onset and late-onset Pompe disease. Respiratory muscle weakness may persist regardless enzyme replacement therapy. This systemic review and meta-analysis aim to assess the effect of respiratory muscle training (RMT) on respiratory muscle strength, functional endurance, and pulmonary function in patient with Pompe disease. Methods: PubMed, EMBASE, and Cochrane databases were searched up until Aug 2024. Studies examining the therapeutic effects of RMT in patients with Pompe disease were included. Outcome measures included the change in maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), six-minute walking test (6MWT), pulmonary function before after RMT, quality of life and adverse events. Results: The meta-analysis consisted of 5 single-arm studies, including 31 patients in total. Regarding inspiratory muscle strength, RMT has significantly improving MIP (8.71 cmH2O; 95% CI, 6.23-11.19, p < 0.001) and MEP (12.15 cmH2O; 95% CI, 10.55-13.74, p < 0.001) in both types of Pompe disease. However, no significant change regarding 6MWT. No serious adverse events were reported. Conclusions: Our meta-analysis revealed that RMT may increase inspiratory muscle and expiratory muscle strength, but may not have an effect on 6MWT in patients with Pompe disease. RMT has potential to be integrated into the cardioplulmonary rehabilitation for patients with Pompe disease. Further large randomized controlled trials are needed to verify the efficacy and safety of RMT in patients with Pompe disease.

Fire safety characteristics of natural gas with hydrogen admixture

The increasing pressure to decarbonise energy production leads to the need to use low or zero carbon fuels or energy carriers. One of the promising fuels of the future is hydrogen, which is carbon-free if renewable energy sources are used for its production. However, the capacity for hydrogen production is currently insufficient to make it applicable on a large scale. Adding hydrogen to natural gas allows for a reduced carbon footprint without costly modifications to pipeline distribution network. However, changing the composition of gas in transport and distribution facilities requires a thorough assessment of the impact on operational safety. Fire safety of flammable mixtures is commonly assessed on the basis of explosive limits and other parameters. Although methods are available to calculate these parameters based on the composition of the mixtures being evaluated, the final safety assessment should rely on actual measured values. The scope of this work is to determine the explosion limits of natural gas from the transit system and changes in the limits caused by the addition of hydrogen at the concentration levels of 10% and 20% (v/v). Obtained experimental results were further compared with theoretically calculated values. Attention was also paid to the change in maximum explosion pressure, maximum pressure rise rate and oxygen concentration limits (LOC). As a result, valuable data on the expansion of the explosion limits of natural gas after the addition of hydrogen are presented.

Telemedical strategies for improving systolic blood pressure control in secondary prevention of cerebrovascular events-a systematic review and meta-analysis

BackgroundStroke remains the second leading cause of death worldwide, with a 20 % risk of recurrence within 5 years. Preventing secondary stroke events is crucial for patient management. Kraft et al. highlighted the potential of telemedicine in secondary prevention, but noted the need for further research. Our study incorporates recent trials to provide an updated analysis of telemedical strategies in stroke prevention. MethodsWe reviewed and analyzed RCTs and observational studies from PubMed, Cochrane, Google Scholar, and Clinicaltrials.gov (May 19, 2016 - March 20, 2024) comparing telephone-based follow-up to standard care in stroke patients. The meta-analysis focused on SBP changes within 12 months. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) and observational studies, sourced from PubMed, Cochrane, Google Scholar, and ClinicalTrials.gov (May 19, 2016 – March 20, 2024). We compared telephone-based follow-up to standard care in stroke patients, and the primary outcome was systolic blood pressure (SBP) changes within 12 months. ResultsOur systematic review included data from 21,904 patients. The meta-analysis focused on studies with comparable systolic blood pressure (SBP) data. It involved 3,501 individuals in the control group and 3,485 in the experimental group. The analysis revealed a significant reduction in SBP with telemedicine strategies for secondary stroke prevention, with a p-value of 0.003. Additionally, a systemic review of the included studies demonstrated that these strategies improved medication adherence, lifestyle habits, and physical performance, positively correlating with better health outcomes and reduced mortality risk. ConclusionWith the inclusion of recent clinical trials, our updated systematic review and meta-analysis concludes that telemedicine supports secondary prevention in cerebrovascular diseases, particularly blood pressure control. While telemedicine may have a role in reducing recurrent stroke risk, we believe further studies with longer follow-up periods are needed to validate the role of telemedical strategies in reducing recurrence rates.

Management of preoperative hypertension and anxiety based on early monitoring of pulse rate before cataract surgery.

Few studies have addressed the clinical impact of fluctuation in pulse rate before cataract surgery. This study aimed to determine the effectiveness of prior pulse monitoring and intervention to prevent blood pressure changes in patients undergoing cataract surgery under local anesthesia. Retrospective study METHODS: Patients who underwent cataract surgery under local anesthesia were included. In the pulse rate (PR) group, intervention was performed on the basis of early monitoring of blood pressure and PR changes. In the conventional group, blood pressure was managed on the basis of blood pressure alone. Systolic blood pressure, diastolic blood pressure, intraoperative nicardipine use, and physician consultation time were retrospectively compared between the groups. The study included 684 eyes from 684 patients aged 73.5 ± 9.5 years (PR group: 297 eyes, conventional group: 387 eyes). No intergroup differences were found in systolic blood pressure or pulse and heart rates; however, diastolic blood pressure was significantly lower in the PR group than in the conventional group at both the beginning and the end of surgery (P <.001 and P = .0028, respectively). Intravenous nicardipine administration in the operating room was significantly less frequent in the PR group (P = .041), and physician consultation time after entering the operating room and at the beginning of surgery was significantly shorter in the PR group (both P <.001). Early monitoring of PR with blood pressure and intervention were effective for preventing preoperative hypertension.

Efficacy of Meal Replacement Products on Weight and Glycolipid Metabolism Management: A 90-Day Randomized Controlled Trial in Adults with Obesity

Background: The global obesity issue is growing increasingly serious, impacting personal health, economic development, and the sustainability of medical systems. There is an urgent need for effective weight loss strategies that can be widely implemented. This study conducted a 90-day randomized controlled trial to assess the impact of meal replacement products on weight management and glycolipid metabolism in adults with obesity. Methods: Adults with obesity meeting the inclusion and exclusion criteria were divided into three groups: the meal replacement group (n = 19), the diet control group (n = 19), and the normal diet group (n = 22). The meal replacement group used specially formulated meal replacement products for dinner, and the diet control group reduced the intake of staple food at lunch, both controlling daily energy intake between 1200 kcal and 1300 kcal, while the normal diet group maintained their regular dietary habits. Relevant indicators were measured at baseline and after 45 and 90 days of intervention. Results: The results showed that both the meal replacement group and the diet control group experienced significant decreases in weight, BMI, and body fat percentage, with the meal replacement group showing a more pronounced weight loss effect. The weight loss of the meal replacement group at 45 and 90 days was 4.44 ± 1.84 kg and 7.38 ± 3.24 kg, the diet control group was 2.62 ± 2.28 kg and 4.08 ± 2.94 kg, and the normal diet group was 0.66 ± 1.73 kg and 0.97 ± 2.02 kg. The decrease in BMI at 45 and 90 days for the meal replacement group was 1.08 ± 0.78 kg/m2 and 2.17 ± 1.57 kg/m2, for the diet control group was 0.82 ± 0.80 kg/m2 and 1.39 ± 1.16 kg/m2, and for the normal diet group was 0.19 ± 0.71 kg/m2 and 0.21 ± 0.96 kg/m2. The decrease in body fat percentage at 45 and 90 days for the meal replacement group was 1.76 ± 0.68% and 3.67 ± 2.62%, for the diet control group was 1.02 ± 1.11% and 1.52 ± 1.79%, and for the normal diet group was 0.81 ± 1.09% and 0.53 ± 0.93%. In addition, the decrease in BMI and body fat percentage in the meal replacement group was also significantly higher than in the other two groups. In terms of metabolic indicators, there were no significant differences in the changes of blood pressure, blood lipids, blood sugar, and ALT levels among the three groups during the intervention period. Conclusions: In summary, the results indicate that meal replacement products can significantly reduce weight and body fat percentage without affecting metabolic health.

Biphasic effects of single-dose intravenous injection of uridine adenosine tetraphosphate on blood pressure in mice

PurposeTo explore the effects of a single dose of uridine adenosine tetraphosphate (Up4A) administered through the tail vein, on the blood pressure of mice.MethodsThe mice were separated into three groups: the Up4A group, the norepinephrine (NA) group, and the α, β-methylene adenosine triphosphate (α, β-meATP) group. Each group of mice were injected drugs through the tail vein at 1, 3, 10, and 30 nmol/kg doses in an ascending order. Additionally, six mice were injected Up4A through the tail vein at 20, 40, 60, and 80 nmol/kg doses in an ascending order. The administration intervals for each dose were 20 min.ResultsMice in these groups experienced a rapid increase in blood pressure, reaching its peak within 10 s after drug administration. It took approximately 120 s for the blood pressure to return to baseline levels after the administration of the drugs in both the NA and α, β-meATP groups. After higher doses of Up4A were administered to the mice, their blood pressure exhibited biphasic changes. Initially, blood pressure of the mice rapidly dropped to a minimum within 10 s, then rose rapidly to a peak within 30 s. Subsequently, it gradually declined, taking around 10 min to return to the levels before the drug administration.ConclusionCompared to NA and α, β-meATP, Up4A, which contains purine and pyrimidine components, displayed a weaker blood pressure-elevating potency. Through its corresponding structure, Up4A exerted vasodilatory and vasoconstrictive effects throughout the entire experiment resulting in biphasic changes in blood pressure.

Numerical modeling of heat transfer mechanism in remote sensing bulb of thermal expansion valves

Thermal management of automotive systems has garnered a lot of focus in recent times to improve the energy efficiency of vehicles and address the challenge of global warming. In combustible fuel vehicles, the heat pump compressor is driven by the engine power which leads to changes in operating condition of the cycle while the vehicle is in motion. In electric vehicles, a combined thermal management strategy handles both cabin and battery pack cooling/heating depending on the ambient conditions and power requirements by adjusting refrigerant flow rates and flow directions with sophisticated valves. Irrespective of the vehicle type, effective variable refrigerant flow control is prerequisite to ensure optimum thermal comfort with minimum energy. Thermal expansion valves (TXV) are the most widely used method for regulating mass flow rate of refrigerant during the expansion step of the vapor compression cycle based on the principle of trying to maintain a fixed degree of superheat at the evaporator outlet. Conventional models of the thermal expansion valve ignore the time lag between fluctuation of temperature at the evaporator outlet and the corresponding change in pressure of the TXV remote sensing bulb, treating the valve as an instantaneous element during transient operation. This paper presents a novel method for determining the temperature profile and time constant of the remote sensing bulb response using numerical methods, in an attempt to capture the dynamics of thermal expansion valve in active heat pump cycle. Finite difference method was used to solve for the conduction heat transfer between the bulb and the heat exchanger outlet tube in perfect thermal contact applying the necessary boundary conditions. This improved modeling approach will be helpful in better prediction of the dynamic behavior of thermal expansion valves and how it influences the evaporative heat exchanger performance during transient operations to determine control algorithm and strategies.

Investigation of smoothed particle hydrodynamics (SPH) method for modeling of two-phase flow through porous medium: application for drainage and imbibition processes

The drainage and imbibition processes are critical mechanisms in petroleum engineering. These processes in a porous medium are controlled by surface forces and pressure gradients. The study of these processes in the pore scale by common simulators always has limitations in multiphase flow modeling. Also, obtaining relative permeability curves through laboratory analysis requires expensive equipment. Additionally, these laboratory experiments are quite expensive and may introduce significant uncertainties. For this purpose, this study investigated the creation of relative permeability curves and their effect on oil production. Initially, single-phase fluid and two-phase droplet flow within a fracture with both soft and rough surfaces were utilized to validate the formulation of the Smoothed Particle Hydrodynamics (SPH) method. Then, by using three randomly constructed porous medium models, the imbibition and drainage processes have been studied. Finally, sensitivity study has been carried out on critical parameters related to fluid flow dynamics in the porous environment, including pressure changes, wettability, and heterogeneity in drainage and imbibition processes. The simulation results were consistent with current theories; therefore, it is reasonable to consider SPH to characterize the fluid flow dynamic during the drainage and imbibition processes. According to sensitivity studies, pressure gradient (residual saturation of displaced fluid is about 5.65% and 8.44%) and heterogeneity (the residual saturation of the displaced fluid was 4.04% and 2.98%) have the largest impact on flow modeling in both drainage and imbibition processes and wettability (the residual saturation became 36.62% and 5.12%) has significant effect on the drainage process through porous medium. In general, fluid flow dynamic studies can be performed using the SPH method to model fluid flow in simple and complex porous medium under various flow conditions. The SPH method can also be used as an applicable tool to investigate the hydrocarbon fluids flow within larger geometries in the future.