Changes In Pressure Research Articles

Comparative morphology in the context of facial reduction: Modularity in primate, dog, and bat crania.

Biological variation in the mammalian skull is the product of a series of factors including changes in gene expression, developmental timing, and environmental pressures. When considering the diversity of extant mammalian crania, it is important to understand these mechanisms that contribute to cranial growth and in turn, how differences in cranial morphology have been attained. Various researchers, including Dr. Sue Herring, have proposed a variety of mechanisms to explain the process of cranial growth. This work has set the foundation on which modern analysis of craniofacial morphology happens today. This study focused on the analysis of modularity in three mammalian taxa, all of which exhibit facial reduction. Specifically, we examined facial reduction as a morphological phenomenon through the use of two-module and six-module modularity hypotheses. We recorded three-dimensional coordinate data for 55 cranial landmarks that allowed us to analyze differences in cranial shape in these three taxa (primates n = 88, bats n = 64, dogs n = 81). When assessing modularity within the two-module modularity hypothesis specifically, dogs exhibited the lowest levels of modularity, while bats and primates both showed a slightly more modular covariance structure. We further assessed modularity in the same sample using the Goswami six-module model, where again dogs exhibited a low degree of modularity, with bats and primates being more moderate. We then broke the sample into subsets by analyzing each morphotype separately. We hypothesized that the modularity would be more pronounced in the brachycephalic morphotype. Surprisingly, we found that in brachycephalic dogs, normocephalic dogs, brachycephalic primates, and normocephalic primates, there was a moderate degree of modularity. Brachycephalic bats had a low degree of modularity, while normocephalic bats were the most modular group observed in this study. Based on these results, it is evident that facial reduction is a complex and multifaceted phenomenon with unique morphological changes observed in each of the three taxa studied.

Improving the management of type 2 diabetes in China using a multifaceted digital health intervention in primary health care: the SMARTDiabetes cluster randomised controlled trial

There is limited evidence, mainly from high-income countries, that digital health interventions improve type 2 diabetes (T2DM) care. Large-scale implementation studies are lacking. A multifaceted digital health intervention comprising: (1) a self-management application ('app') for patients and lay 'family health promotors' (FHPs); and (2) clinical decision support for primary care doctors was evaluated in an open-label, parallel, cluster randomized controlled trial in 80 communities (serviced by a primary care facility for >1000 residents) in Hebei Province, China. People >40 years with T2DM and a glycated haemoglobin (HbA1c) ≥7% were recruited (∼25/community). After baseline assessment, community clusters were randomly assigned to intervention or control groups (1:1) via a web-based system, stratified by locality (rural/urban). Control arm clusters received usual care without access to the digital health application or family health promoters. The primary outcome was at the participant level defined as the proportion with ≥2 "ABC" risk factor targets achieved (HbA1c<7.0%, blood pressure < 140/80mmHg and LDL-cholesterol < 2.6mmol/L) at 24 months. A total of 2072 people were recruited from the 80 community clusters (40 urban and 40 rural), with 1872 (90.3%) assessed at 24 months. In the intervention arm, patients used FHPs for support more in rural than urban communities (252 (48.6%) rural vs 92 (21.5%) urban, p<0.0001). The mean monthly proportion of active app users was 46.4% (SD 7.8%) with no significant difference between urban and rural usage rates. The intervention was associated with improved ABC control rates (339 [35.9%] intervention vs 276 [29.9%] usual care; RR 1.20, 95% CI 1.02-1.40; p=0.025), with significant heterogeneity by geography (rural 220 [42.6%] vs 158 [31.0%]; urban 119 [27.9%] vs 118 [28.6%]; p=0.022 for interaction). Risk factor reductions were mainly driven by improved glycaemic control (mean HbA1C difference-0.33%, 95% CI-0.48 to-0.17; p=0.00025 and mean fasting plasma glucose difference-0.58mmol, 95% CI-0.89 to-0.27; p=0.00013). There were no changes in blood pressure and LDL-cholesterol levels. A multifaceted digital health intervention improved T2DM risk factor control rates, particularly in rural communities where there may be stronger relationships between patients and doctors and greater family member support. National Health and Medical Research CouncilGlobal Alliance for Chronic Diseases (ID 1094712).

Tirzepatide and blood pressure reduction: stratified analyses of the SURMOUNT-1 randomised controlled trial

BackgroundTreating obesity may be a pathway to prevent and control hypertension. In the SURMOUNT-1 trial in people with obesity or overweight with weight-related complications, 72-week tirzepatide treatment led to clinically...

Application of articaine in endoscopic endonasal dacryocystorhinostomy: a retrospective study

BackgroundTo investigate the comparative effects of local anesthesia using lidocaine with adrenaline vs. articaine with adrenaline in endoscopic endonasal dacryocystorhinostomy (EN-DCR).MethodsThis retrospective study included a total of 180 patients. These patients were categorized into two groups: the lidocaine group, which received 2% lidocaine (1:100,000 adrenaline), and the articaine group, which received 4% articaine (1:100,000 adrenaline) for local anesthesia. The study compared anesthesia efficacy, intraoperative pain levels, intraoperative bleeding, as well as differences in heart rate and blood pressure between the two groups.ResultsThe articaine group demonstrated a significantly lower visual analog scale (VAS) pain score when compared to the lidocaine group, measuring at 4.4 ± 0.6 cm vs. 5.0 ± 1.0 cm, respectively (P &amp;lt; 0.0001). Additionally, the articaine group exhibited a higher anesthesia efficacy compared to the lidocaine group (89.0% vs. 76.6%, p = 0.0487). Notably, the articaine group experienced less nasal mucosal bleeding during the surgery in contrast to the lidocaine group (p = 0.004). However, there were no statistically significant differences in changes in blood pressure and heart rate between the two groups (p &amp;gt; 0.05).ConclusionThis study demonstrated that 4% articaine (1:100,000 adrenaline) has superior clinical effectiveness in comparison to 2% lidocaine (1:100,000 adrenaline) in EN-DCR.

An Insight into Perfusion Anisotropy within Solid Murine Lung Cancer Tumors

Blood vessels are essential for maintaining tumor growth, progression, and metastasis, yet the tumor vasculature is under a constant state of remodeling. Since the tumor vasculature is an attractive therapeutic target, there is a need to predict the dynamic changes in intratumoral fluid pressure and velocity that occur across the tumor microenvironment (TME). The goal of this study was to obtain insight into perfusion anisotropy within lung tumors. To achieve this goal, we used the perfusion marker Hoechst 33342 and vascular endothelial marker CD31 to stain tumor sections from C57BL/6 mice harboring Lewis lung carcinoma tumors on their flank. Vasculature, capillary diameter, and permeability distribution were extracted at different time points along the tumor growth curve. A computational model was generated by applying a unique modeling approach based on the smeared physical fields (Kojic Transport Model, KTM). KTM predicts spatial and temporal changes in intratumoral pressure and fluid velocity within the growing tumor. Anisotropic perfusion occurs within two domains: capillary and extracellular space. Anisotropy in tumor structure causes the nonuniform distribution of pressure and fluid velocity. These results provide insights regarding local vascular distribution for optimal drug dosing and delivery to better predict distribution and duration of retention within the TME.

GABA-immunoreactivity in Neuroepithelial Bodies of Spontaneously Hypertensive Rats

Neuroepithelial bodies (NEBs) are complex sensory receptors dispersed throughout the intrapulmonary airways. They are composed of pulmonary neuroendocrine cells (PNECs) which have a large amount of dense-core vesicles containing calcitonin gene-related peptide (CGRP), serotonin (5HT), substance P (SP) and δ-aminobutyric acid (GABA). NEBs are densely innervated by vagal sensory terminals, dorsal root afferents and intrinsic motor fibres. Their location, neurochemical composition and dense innervation make NEBs a key component for the regulation of lung homeostasis. Pulmonary arterial hypertension is a rare disease characterized by morphological alterations in the microcirculation of the lungs causing a wide array of complications and high mortality. Spontaneously hypertensive rats (SHRs) are a common model for essential hypertension, that may develop secondary pulmonary hypertension and thus can be used as an animal model to study pulmonary pressure changes. The present study focuses on the immunohistochemical demonstration of GABA in the NEBs and its potential role in the regulation of the pulmonary pressure. Two groups of SHRs were used and age-matched normotensive Wistar Kyoto (WKY) rats served as controls. We found single PNECs and clusters of GABA-immunoreactive cells protruding into the lumen of the intrapulmonary airways in all examined groups of SHRs and in the normotensive WKY rats. However, the expressional levels statistically differed within the two age groups of SHRs and the controls. Specifically, the NEBs and PNECs in 1-month-old SHRs and particularly in 3-month-old SHRs showed more intense GABA-immunostaining compared to the WKY rats. In conclusion, NEBs and PNECs react to the alterations of the pulmonary pressure homeostasis by an increased GABA expression as a preventive or reactive regulation mechanism against developing pulmonary hypertension.

Clinical Impact of the Use of Ologen in Filtering Surgery Performed in Uncontrolled Glaucoma

Introduction: To compare the efficacy and safety of trabeculectomy with a collagen matrix implant (Ologen®) versus trabeculectomy with mitomycin C (MMC) versus trabeculectomy with both Ologen® and MMC (OLO + MMC). Methods: This non-randomized study included 119 eyes of 101 patients with uncontrolled open-angle glaucoma who underwent trabeculectomy, either alone or combined with phacoemulsification. The data were initially recorded following a standard surgical protocol, using an electronic database with structured fields. The patients were divided into three groups: 44 received trabeculectomy with adjunctive MMC (MMC group), 34 received surgery with Ologen® (OLO group), and 41 received surgery with both Ologen® and MMC (OLO + MMC group). The main outcome measures were the change in intraocular pressure (IOP), change in number of medications needed, complete success rate (defined as IOP ≤ 20 mmHg and at least 20% IOP reduction without hypotensive medications), rate of complications, and rate of postoperative interventions. The follow-up period was 36 months. Results: IOPs significantly decreased (p = 0.01) in all groups across all study visits, decreasing from 19.8 ± 4.6 mmHg to 12.7 ± 4.2 mmHg in the MMC group, from 20.5 ± 4.7 mmHg to 13.9 ± 3.5 mmHg in the OLO group, and from 23.5 ± 6.1 mmHg to 13.1 ± 3.5 mmHg in the OLO + MMC group. After correcting for the baseline IOP, only the first two postoperative visits (first week and first month) showed a significantly greater IOP reduction in the OLO + MMC group. The number of hypotensive medications was significantly reduced from 3.1 ± 0.6 to 0.56 ± 1.1 in the MMC group, from 2.9 ± 0.4 to 0.83 ± 1.1 in the OLO group, and from 3.0 ± 0.6 to 0.45 ± 0.95 in OLO + MMC group, with no statistically significant differences among the groups (p = 0.57). The complete success rates were 63.6% in the MMC group, 67.6% in the OLO group, and 80.5% in the OLO +MMC group, with no statistically significant differences between the groups (p = 0.21). Suture release was significantly more frequent in the MMC group (86.1%) than in the OLO group (62.1%) and in the OLO + MMC group (45.9%; p = 0.02). Bleb needling, with (33.3%; p = 0.005) or without (66.7%; p = 0.0001) 5-fluorouracil injection (5-FU), was significantly more common in the MMC group. The highest complete success rate (61%) was observed in the OLO + MMC group. Conclusions: The use of Ologen® and mitomycin C provided similar surgical IOP reduction in glaucoma surgery compared with either MMC or Ologen® alone, but significantly reduced the need for postoperative interventions.

Reasons for Use and Perceived Effects of Medical Cannabis: A Cross-Sectional Statewide Survey

Introduction: Medical cannabis (MC) is available upon certification for one of several qualifying conditions in Florida, USA. Previous studies suggested that some people seek cannabis for medical conditions/symptoms beyond those legally permitted. Yet, data remains limited on patient motives for seeking MC and their experiences around its impact on their health. We aimed to compare reported qualifying conditions for MC certification with the most frequently self-reported reasons for using MC while assessing the alignment between the two and understand the perceived impacts of MC on self-reported conditions and symptoms. Methods: We conducted a cross-sectional study using survey data from the Medical Marijuana &amp;amp; Me (M3) Databank of individuals receiving MC in Florida, USA, in 2022. Participants were recruited via convenience sampling from nine MC clinics/clinic networks across Florida and were asked to fill out an online survey. The study measures included sociodemographic variables, self-reported health conditions, self-reported main reasons for using MC, self-reported qualifying conditions for MC certification, and self-reported perceived impact of MC on health conditions. We cross-tabulated reported qualifying conditions and reasons for MC use and reported the perceived impact per condition. Results: A total of 632 participants completed the survey, of whom 396 (62.66%) were female, and 471 (74.53%) were non-Hispanic White. The median (IQR) age was 45 (35, 58). The most frequently reported qualifying conditions were post-traumatic stress disorder (PTSD) (n=187, 29.59%), a condition not on the qualifying conditions list (n=175, 27.69%), medical conditions of the same kind/comparable to those listed (n=140, 22.15%), and chronic nonmalignant pain (n=62, 25.63%). The top ten most frequently reported reasons for using MC were anxiety (n=383, 60.60%), chronic pain (n=278, 43.99%), depression (n=252, 39.87%), PTSD (n=220, 34.81%), headaches/migraine (n=134, 21.20%), fibromyalgia (n=67, 10.60%), attention-deficit/hyperactivity disorder (ADHD) (n=59, 9.34%), bipolar disorder (n=53, 8.39%), high blood pressure (n=41, 6.49%), and cancer, (n=18,2.85%). Of respondents, 70-90% with each qualifying condition reported it as one of the main reasons for using MC. Most respondents reported improvement of anxiety (n=430/451, 95.34%), depression (n=381/392, 97.20%), chronic pain (n=305/310, 98.39%), insomnia/ sleeping problems (n=225/295, 86.44%), PTSD (n=247/270, 91.48%), headaches/ migraine (n=172/218, 78.90%), ADHD (n=82/123, 66.67%), bipolar disorder (n=79/89, 88.76%), and fibromyalgia (n=77/82, 93.90%). Most respondents were unsure/reported no change in blood pressure (n=93/162, 57.41%). A small percentage reported perceived worsening impacts on their conditions. Conclusion: Qualifying conditions and self-reported reasons for using MC aligned for most respondents. Yet, a notable proportion of respondents sought MC for broader treatment effects beyond those delineated by the officially recognized qualifying conditions in Florida, USA. Most patients perceived positive effects, including those with limited available evidence on efficacy.

Fast and accurate estimation of selection coefficients and allele histories from ancient and modern DNA.

We here present CLUES2, a full-likelihood method to infer natural selection from sequence data that is an extension of the method CLUES. We make several substantial improvements to the CLUES method that greatly increases both its applicability and its speed. We add the ability to use ARGs on ancient data as emissions to the underlying HMM, which enables CLUES2 to use both temporal and linkage information to make estimates of selection coefficients. We also fully implement the ability to estimate distinct selection coefficients in different epochs, which allows for the analysis of changes in selective pressures through time, as well as selection with dominance. In addition, we greatly increase the computational efficiency of CLUES2 over CLUES using several approximations to the forward-backward algorithms and develop a new way to reconstruct historic allele frequencies by integrating over the uncertainty in the estimation of the selection coefficients. We illustrate the accuracy of CLUES2 through extensive simulations and validate the importance sampling framework for integrating over the uncertainty in the inference of gene trees. We also show that CLUES2 is well-calibrated by showing that under the null hypothesis, the distribution of log-likelihood ratios follows a chi-squared distribution with the appropriate degrees of freedom. We run CLUES2 on a set of recently published ancient human data from Western Eurasia and test for evidence of changing selection coefficients through time. We find significant evidence of changing selective pressures in several genes correlated with the introduction of agriculture to Europe and the ensuing dietary and demographic shifts of that time. In particular, our analysis supports previous hypotheses of strong selection on lactase persistence during periods of ancient famines and attenuated selection in more modern periods.

Pharmacological Modulation of Intrarenal Pressure in a Porcine Model Using a Novel Isoprenaline-Eluting Guidewire.

Introduction: Several complications of retrograde intrarenal surgery have been attributed to inadvertent increases in intrarenal pressure. We recently described the development of an innovative isoprenaline-eluting guidewire (IsoWire). The objective of this study was to investigate the impact of this IsoWire on the intrarenal pressure and evaluate its safety. Materials and Methods: This study was performed in 17 renal units using a porcine model. As controls, the intrarenal pressure, heart rate, and mean arterial pressure were measured for a duration of six minutes with a standard guidewire placed in the renal pelvis. For the experiment, the conventional guidewire was substituted with the IsoWire and the same parameters were measured. Blood samples were taken at one-minute intervals to measure plasma isoprenaline levels. This procedure was repeated on the opposite side. Results: The mean intrarenal pressure reduction was 29% (95% CI: 13%-53%). The mean isoprenaline effect time was 174 seconds. No changes in heart rate (p = .908) or mean arterial pressure (p = .749) were recorded after IsoWire insertion. Plasma isoprenaline levels were below the quantitation threshold. Isoprenaline concentrations in the plasma were below the quantification threshold. Ureteroscopy revealed no ureteral lesions. Conclusions: The IsoWire demonstrated a safe and effective reduction of intrarenal pressure. Additional research is necessary to determine whether ureteral smooth muscle relaxation generated by isoprenaline facilitates easier insertion of a ureteral access sheath, decreases the incidence of ureteral access sheath related ureteral lesions, or even encourage the practice of sheathless retrograde intrarenal surgery.

Predicting Wall Pressure in Shock Wave/Boundary Layer Interactions with Convolutional Neural Networks

Within the dynamic realm of variable-geometry shock wave/boundary layer interactions, the wall parameters of the flow field undergo real-time fluctuations. The conventional approach to sensing these changes in wall pressure through sensor measurements is encumbered by a cumbersome process, leading to diminished efficiency and an inability to provide swift predictions of wall parameters. This paper introduces a data-driven methodology that leverages non-contact schlieren imaging to predict wall pressure within the flow field, a technique that holds promise for informing the optimized design of variable-geometry systems. A sophisticated deep learning framework, predicated on Convolutional Neural Networks (CNN), has been engineered to anticipate alterations in wall pressure stemming from high-speed shock wave/boundary layer interactions. Utilizing an impulsive wind tunnel with a Mach number of 6, we have procured a sequence of schlieren images and corresponding wall pressure measurements, capturing the continuous variations induced by an attack angle from a shock wave generator. These data have been instrumental in compiling a comprehensive dataset for the training and evaluation of the CNN. The CNN model, once trained, has adeptly deduced the distribution of wall pressure from the schlieren imagery. Notwithstanding, it was observed that the CNN’s predictive prowess is marginally diminished in regions where pressure variations are most pronounced. To assess the model’s generalization capabilities, we have segmented the dataset according to different temporal intervals for network training. Our findings indicate that while the generalization of all models crafted was less than optimal, Model 4 demonstrated superior generalization. It is thus suggested that augmenting the training set with additional samples and refining the network architecture will be a worthwhile endeavor in subsequent research initiatives.

Effects of training load on heart rate variability and blood pressure in track and field athletes and skiers

BACKGROUND: Adaptation of human body to the harsh conditions of the European North remains a topic of ongoing interest, despite numerous studies on the subject. There is a need to study population groups whose daily activities involve physical activity in extreme northern conditions. One such group includes athletes who participate in endurance sports. For athletes engaged in cyclical sports, competitive activities becomes can be particularly demanding, requiring sustained physical exertion and maximum power generation. Training and competing in harsh conditions place significant strain on the body’s cardiovascular regulation mechanisms. Over time, this may result in detrimental structural and biochemical changes in the cardiovascular system. AIM: To identify the patterns of changes in heart rate regulation among track and field athletes and skiers after a training load. MATERIAL AND METHODS: Athletes from the Arkhangelsk region, including skiers and track and field athletes in the mass sports categories, who regularly compete in regional events, took part in the study. The studies took place in the medical offices of sports complexes, where the UPFT-1/30“Psychophysiologist” device was used to record and analyze cardiointervalograms. Blood pressure was recorded before and after training sessions using the Criticare System 8100H monitor. RESULTS: The initial variational span (VR) values of the duration of cardio intervals before exercise were slightly lower than the reference values in both the group of skiers and the group of athletes. At the same time, the mean square deviation (SD) values initially fell within normal range. Following the training load, both groups experienced a statistically significant decrease in SD and VR values, falling below the lower limit of the permissible range. Furthermore, spectral analysis of the cardiac intervals before exercise indicated a high level of neurohumoral regulation. After exercise, there was a statistically significant decrease in the initial values of TP in both groups, aligning with the average level of neurohumoral regulation. CONCLUSION: The results obtained in track and field athletes with a predominant anaerobic training load and skiers with a predominant aerobic load suggest that the training load of a predominantly aerobic nature may lead to less pronounced stress on the regulatory systems. This hypothesis was further supported by the results of the changes in blood pressure.

Effect of back diffusion on energy efficiency of electrochemical ammonia compressor

Conventional ammonia compression technologies consume significant energy, leading to substantial greenhouse gas emissions. We analyzed the back-diffusion of ammonia in an electrochemical ammonia compressor (EAC) and evaluated its performance and efficiency based on temperature and relative humidity (RH). We evaluated EAC performance under various conditions and developed a model to analyze voltage and pressure changes. Ammonia's permeability is about 890 times higher than hydrogen, increasing compression time due to back diffusion. As temperature rises, the overpotential increases, with a 0.035 V rise at 100 °C compared to 60 °C, and back-diffusion extends compression time by 130 s. Lower humidity increases overpotential, with a 0.099 V rise at 10% RH compared to 50% RH, but reduces back diffusion by 165 s. This study improves our understanding of EACs and guides future performance enhancements. We aim to develop a new membrane to enhance ammonium ion movement and minimize ammonia back-diffusion.

Analyzing the Diversion Effect of Debris Flow in Cross Channels Utilizing Two-Phase Flow Theory and the Principle of Energy Conservation

The movement process of debris flow in the complex roads system is important for risk evaluation and emergency rescue. This paper presents an in-depth study of the diversion effect of debris flow in cross channels, a common branching structure in both natural and engineered environments, especially in the field of urban debris flow prevention. A mathematical model is established based on the conservation of mass, momentum, and energy, and a solid–liquid two-phase motion equation for debris flow is derived from two-phase flow theory. A numerical solution method, combining the finite difference method and finite volume method, is employed to discretize and solve the equation. The model’s validity and effectiveness are confirmed through a numerical simulation of a typical engineering case and comparison with existing experimental data or theoretical results. This study reveals that debris flow at cross channels exhibits a diversion phenomenon, with some debris flow continuing downstream along the main channel and some diverting into the branch channel. The diversion rate, defined as the ratio of outlet flow to inlet flow of the branch channel, indicates the magnitude of this effect. This research shows that the solid–liquid ratio, inflow, width ratio, height ratio, and angle of the cross channel significantly impact the diversion effect. A series of numerical simulations are conducted by altering these parameters as well as the physical properties of debris flow and boundary conditions. These simulations analyze changes in flow rate, velocity, pressure, and other parameters of debris flow at cross channels, providing insights into the factors and mechanisms influencing the diversion effect. This research offers a robust instrument for comprehending and forecasting the dynamics of urban debris flows. It contributes significantly to mitigating the effects of debris flows on city infrastructure and enhancing the safety of city dwellers.

Long-term effects of COVID-19 on endothelial function, arterial stiffness, and blood pressure in college students: a pre-post-controlled study

BackgroundThe COVID-19 has been shown to have negative effects on the cardiovascular system, but it is unclear how long these effects last in college students. This study aimed to assess the long-term impact of COVID-19 on arterial stiffness, endothelial function, and blood pressure in college students.MethodsWe enrolled 37 college students who had been infected with COVID-19 for more than 2 months. Brachial artery flow-mediated dilation (FMD) was used to assess endothelial function, while arterial stiffness was evaluated using the ABI Systems 100, including variables such as ankle-brachial index (ABI), brachial-ankle pulse wave velocity (baPWV), carotid-femoral pulse wave velocity (cfPWV), heart rate (HR), and blood pressure (BP).ResultsOur results showed that FMD was significantly impaired after COVID-19 infection (p < 0.001), while cfPWV and systolic blood pressure (SBP) were significantly increased (p < 0.05). Simple linear regression models revealed a significant negative correlation between post-COVID-19 measurement time and baPWV change (p < 0.01), indicating an improvement in arterial stiffness over time. However, there was a significant positive correlation between post-COVID-19 measurement time and diastolic blood pressure (DBP) change (p < 0.05), suggesting an increase in BP over time. There were no significant differences in ABI and HR between pre- and post-COVID-19 measurements, and no significant correlations were observed with other variables (p > 0.05). Conclusion: Our study demonstrated that COVID-19 has long-term detrimental effects on vascular function in college students. However, arterial stiffness tends to improve over time, while BP may exhibit the opposite trend.

A Comparison Between Water Addition and CO2 Addition to a Diffusion Coflow Flame

ABSTRACT This work compares the effects of adding water vapor and CO2 as diluent to fuel for a diffusion flame at different ambient pressures. The approach of this research is to study numerically a methane diffusion flame with various amounts of water vapor and CO2 added to the fuel, and to compare the flame behaviors with various percentages of water vapor and CO2 content (0% to 65%). This work uses a coflow burner in the PeleLM numerical framework for simulating the flame and computing the combustion behavior. The flame was simulated with pressures of 1.0, 1.4, 5.7, and 11.1 atm. The results extracted and analyzed include temperature profiles at fixed heights and various species mole fractions compared with their values at an equilibrium state condition. The results show that most of the diluent impact does not involve changes in flame chemistry but primarily changes to heat release and heat capacity in the flames. The results also show that the diluent amount has a much larger impact on flame behavior than do changes in pressure.

Enhancement of aluminum powder reaction behavior at high temperatures—Aluminum powders with “sea urchin structure” coated by AP

To solve the problem of high ignition temperature of aluminum powder and easy to burn into blocks at high temperatures, “sea-urchin-structured” aluminum powders (μAl@nAl) obtained by electro-explosion were coated by ammonium perchlorate (AP) on its surface. AP in a high-temperature environment has a rapid decomposition, then the gas production will promote the dispersion of aluminum powder into micro-clusters, thus preventing the aluminum powder agglomeration during the combustion process. The micro-nano composite aluminum powder (μAl@8 %nAl) and physical mixed aluminum powder (μAl + 8 %nAl) coated by AP were completed by solvent volatilization method. The coating surface was observed by scanning electron microscopy. The heat of combustion and pressure curves for different AP contents were tested using a chamber with a constant volume, and the ignition and combustion performance of the AP samples were investigated using a carbon dioxide (CO2) laser ignition device. The AP samples shortened the ignition delay time and improved the combustion performance in the fixed-volume combustion and laser ignition tests. Under atmospheric air, taking into account the theoretical calorific value, pressure curve, and combustion performance, the optimal AP content is 10 %. The thermal decomposition process of two samples was further analyzed using the thermogravimetric and differential scanning calorimetry (TG-DSC) method. The decomposition of AP advanced the first oxidation peak of aluminum powder; however, in the second step oxidation peak, the peak temperature of μAl@8 %nAl@10 %AP sample was delayed compared to μAl + 8 %nAl@10 %AP sample. High-voltage electrical explosions and high-energy laser-induced air shock waves were created to simulate the high-temperature environment of the detonation reaction zone, and pictures of the reaction process and pressure change curves of the “sea urchin structure” aluminum powder coated by AP at high temperatures were recorded. The results showed that the “sea urchin structure” aluminum powder coated by AP exhibited better combustion performance, and the reaction degree of the aluminum powder had been deepened.

Experimental study and correlation analysis for the effect of hydrogen pressure on biomass fluidized hydropyrolysis under N2-H2 mixed atmosphere

The utilization of fluidized bed reactors for the biomass hydropyrolysis vapor upgrading is essential in the conversion of biomass into liquid fuels. Conducting pyrolysis experiments in fluidized bed reactors with a N2-H2 mixed atmosphere is advantageous for system operation as it allows for lower minimum operating velocities, enhances pyrolysis efficiency, and reduces heat loss. This research examines the impact of hydrogen pressure in a bubbling fluidized bed reactor using a N2-H2 mixed carrier gas, with poplar wood as the feedstock and Ni-Moγ/Al2O3 as the catalyst. Through experimental and correlation analyses, significant relationships are observed between hydrogen pressure and the production of liquid and gas-phase products, with varying effects attributed to changes in hydrogen ratio and reaction pressure. Elevated hydrogen ratios facilitate secondary reactions such as the CO2 hydrogenation, resulting in a decline in CO2 production and an elevation in the yields of light hydrocarbons and aqueous phase products. Augmenting the reaction pressure to enhance hydrogen pressure aids in promoting hydrogen saturation and cracking, and amplifying the hydrogen pressure through an increase in the reaction pressure at a specific hydrogen ratio proves more efficacious in enhancing both the quantity and quality of bio-oil produced. In the context of poplar hydropyrolysis vapor upgrading utilizing a Ni-Moγ/Al2O3 catalyst, a hydrogen ratio of 50 % at a reaction pressure of 1.5 MPa emerged as the preferred option for achieving a 12 % bio-oil yield with a moderate average bio-oil carbon number and satisfactory hydrogenation levels. This comprehensive investigation examines the influence of hydrogen pressure on biomass hydropyrolysis, highlighting variations in the impacts of changes in hydrogen ratio and reaction pressure on pyrolysis results. These results offer a theoretical framework for discerning distinctions between hydropyrolysis investigations carried out in pure hydrogen atmospheres versus mixed N2-H2 atmospheres.

First-principles calculations to investigate pressure effects on the crystal structure, electronic and magnetic moment evolution of Fe2Te2

ABSTRACT The electronic structure and magnetic properties of Fe2Te2 are studied by first-principles calculations. The ground state for Fe2Te2 is bi-collinear antiferromagnetic order with Fe magnetic moment (∼2.5 μB). When hydrostatic and uniaxial pressure (Phy or PC ) increased, the density of states at the Fermi-level N(E F ) and the hybrid bandwidth (HBW) of Fe-3d and Te-5p near the Fermi-level both increased slightly accompanied by the decreasing of Fe magnetic moment M Fe(μB). However, compared with 122 type iron-based materials, no significant changes in the band structure, density of states and M Fe were observed when the physical pressure increased. Fe2Te2 is not sensitive to the changes of pressure and it is difficult to induce its superconductivity only by applying its physical pressure.

Inhibition of muscle sympathetic nerve activity in pre-menopausal women: responses to sudden sensory stimuli predict responses to mental stress.

Muscle sympathetic nerve responses to sudden sensory stimuli have been elucidated in several studies on young healthy men, showing reproducible interindividual differences ranging from varying degrees of inhibition to no significant change, with very few subjects showing significant excitation. These individual response patterns have been shown to predict the neural response to mental stress, and coupled blood pressure responses. The aim of this study was to investigate whether pre-menopausal healthy women show similar neural and blood pressure responses. Muscle sympathetic nerve recordings from the peroneal nerve were performed in 34 healthy women (mean age 27±8 years) during sudden sensory stimuli (electrical stimuli to a finger) and 3 minutes of mental stress (forced arithmetics). After sensory stimuli 18 women showed varying degrees of inhibition of muscle sympathetic nerve activity (burst amplitude mean reduction 60%, range 34 to 100%). The remaining 16 showed no inhibition (mean 5%, range -31 to 28%; one subject exhibiting excitation). During 3 minutes of mental stress the normalized change in burst incidence for muscle sympathetic nerve activity correlated with the percentage change of muscle sympathetic nerve activity induced by the sensory stimulation protocol (r=0.64, p=0.0042). In contrast to men, the neural responses did not predict changes in blood pressure. Thus, pre-menopausal females show a similar range of individual differences in defence-related muscle sympathetic neural responses as men, but no associated differences in blood pressure responses. Whether these patterns are unchanged after menopause remains to be investigated.