Pressure Condition Research Articles

Overlooked Impacts of Urban Environments on the Air Quality in Naturally Ventilated Schools Amid the COVID-19 Pandemic

The density, form, and dimensions of urban morphology are important for healthy living conditions in cities, especially if they are related to the climate and air pollution. Morphology and environmental conditions determine the relationship between open and built space, the width of street spaces, the aerodynamic characteristics of wind currents, albedo, and the retention of pollutants, as well as determining the radiative exchange with the atmosphere. Studies on the COVID-19 pandemic have focused on the assumption of a possible relationship between the spread of the SARS-CoV-2 virus and the presence and concentration of airborne particulate matter (PM10 and PM2.5). This paper focuses on the research of indoor air quality (IAQ) in two schools with naturally ventilated classrooms in Ljubljana, Slovenia. The presence of particulate matter (PM2.5 and PM10) and the concentration of CO2 were studied, along with other microclimatic conditions, e.g., ambient temperature, relative humidity, air pressure, and wind conditions. These were compared and assessed via analysis of variance (ANOVA) and Duncan’s post hoc test. The main concern was to see how effective different ventilation strategies are, as well as how the openings in the classroom impact the concentrations of CO2 relative to the concentrations of PM2.5 and PM10 particles as a side effect of these ventilation strategies. The inconsistent application of recommended COVID-19 ventilation strategies suggests that IAQ in naturally ventilated classrooms is highly determined by individual perceptions of indoor air quality. The results also suggest that the IAQ is significantly affected by the schools’ urban environment; however, this is not considered within the national COVID-19 ventilation recommendations. Future ventilation guidelines for pandemics should also include the urban environment as a risk factor for inadequate IAQ, instead of focusing solely on pathogen characteristics.

Utilizing the Random Forest Method for Short-Term Wind Speed Forecasting in the Coastal Area of Central Taiwan

The Taiwan Strait contains a vast potential for wind energy. However, the power grid balance is challenging due to wind energy’s uncertainty and intermittent nature. Wind speed forecasting reduces this risk, increasing the penetration rate. Machine learning (ML) models are adopted in this study for the short-term prediction of wind speed based on the complex nonlinear relationships among wind speed, terrain, air pressure, air temperature, and other weather conditions. Feature selection is crucial for ML modeling. Finding more valuable features in observations is the key to improving the accuracy of prediction models. The random forest method was selected because of its stability, interpretability, low computational cost, and immunity to noise, which helps maintain focus on investigating the essential features from vast data. In this study, several new exogenous features were found on the basis of physics and the spatiotemporal correlation of surrounding data. Apart from the conventional input features used for wind speed prediction, such as wind speed, wind direction, air pressure, and air temperature, new features were identified through the feature importance of the random forest method, including wave height, air pressure difference, air-sea temperature difference, and hours and months, representing the periodic components of time series analysis. The air–sea temperature difference is proposed to replace the wind speed difference to represent atmosphere stability due to the availability and adequate accuracy of the data. A random forest and an artificial neural network model were created to investigate the effectiveness and generality of these new features. Both models are superior to persistence models and models using only conventional features. The random forest model outperformed all models. We believe that time-consuming and tune-required sophisticated models may also benefit from these new features.

Modeling for predicting triaxial mechanical properties of recycled aggregate concrete considering the recycled aggregate replacement

To theoretically investigate the triaxial mechanical behavior of recycled aggregate concrete (RAC), four series of samples, a C30 conventional concrete (CC) and three RACs with different recycled aggregate (RA) replacement ratios (20 %, 50 % and 80 %), were prepared. The triaxial compression tests with 0, 2, 4 and 8 MPa confining pressures were performed. Experimental results showed that the difference in failure stress decreased from 30.0 % to 2.7 % with increasing the confining pressure for the four series of concretes. This means that for failure stress, the influence of RA replacement ratios on the low confining pressure condition should be taken into account while its effect trends to decrease or even can be neglected with increasing the confining pressure. Furthermore, the elastic properties and the evolution of plastic characteristics were also related to the RA replacement ratio. Based on the test results, this study develops a modified elastoplastic model to accurately predict the triaxial mechanical behavior of RAC. The proposed non-integer high order failure criterion can better reflect the confining pressure sensitivity, while the associated flow rule can well describe the elastoplastic transition with increasing the confining pressure. Moreover, the influence of RA replacement was analyzed, and the parameters related to RA replacement ratios were considered in this model. Comparing the numerical simulations with the experimental results, it was concluded that the present modeling can well predict the main mechanical behavior of both CC and RACs by introducing RA dependent parameters.

HUBUNGAN TEKANAN DARAH DENGAN FUNGSI KOGNITIF PADA GERIATRI DI RSUD ULIN BANJARMASIN

One health problems that often occur in elderly is a decline in cognitive function. The brain needs oxygen and glucose reserves to work, if there is a blood vessel blockage, it can cause oxygen and glucose inadequacy which can reduce the work function of brain nerve cells. Hypertension is a medical condition of an elevated vascular blood pressure above normal limits. The purpose of this study was to analyze the relationship between blood pressure and cognitive function in the elderly at RSUD Ulin Banjarmasin. This study is an analytic observational study using a cross-sectional method with total of 32 elderly people were selected using a purposive sampling method. Data was analyzed by using Pearson. The average value systolic blood pressure was 152,2 ± 5,1 from secondary data of medical record, and the average value of cognitive function using the Mini Mental State Examination (MMSE) was 26,3 ± 1,0 with Pearson correlation test results obtained value of p = 0.594 and r = 0.098. These findings provide additional evidence that there is no relation between blood systolic pressure and cognitive function in the elderly in RSUD Ulin Banjarmasin

Study on simulation of cement plug—formation interface stripping failure and main influencing factors

Among the existing gas storage facilities, salt cavern gas storage has the advantages of high injection production efficiency, low gas cushion volume, safety, flexibility, etc. It is of great significance to speed up the construction of underground gas storage by transforming abandoned salt caverns of salt industry into underground gas storage. However, old salt cavern wells cannot be directly converted into gas storage injection and production wells, so the old wellbore must be plugged to ensure the effectiveness of plugging. Therefore, a set of plugging optimization technology for salt cavern gas storage wells is urgently needed. In this paper, a 3D finite element model of the cement plug-formation system based on cohesive element method is established for the milling and plugging of the old well in the salt cavern gas storage section. The results show that under the condition of constant gas storage pressure, a certain degree of small deformation will occur at the bottom of the cement plug after compression, resulting in the shear direction deformation of the cement plug formation cementation interface, and peeling will occur after accumulation to a certain extent. With the increase of simulation time, the length of stripping section gradually increases and tends to be stable, and reaches the limit of stripping failure length. In the process of research, the factors and laws affecting the stripping failure length were also analyzed. It was found that the stripping failure length of cement plug formation cementation interface was related to the maximum operating pressure of gas storage, cement plug length, cement plug diameter, elastic modulus, Poisson’s ratio and other factors. The research results are helpful to judge whether the milling and plugging length of the old well section is sufficient, and provide theoretical guidance for ensuring the long-term safe operation of the gas storage.

Porosity and permeability correction of laumontite-rich reservoirs in the first member of the Shaximiao Formation in the Central Sichuan Basin

The development of a large amount of laumontite cement in clastic reservoirs generate pseudo fractures at normal temperatures and pressures conditions on the ground surface, causing porosity and permeability values to be significantly higher than the actual values of buried conditions. Taking the first member of the Shaximiao Formation in the Middle Jurassic of the Central Sichuan Basin as an example, this study analyzes the material composition, reservoir porosity and permeability, diagenesis, and other characteristics of reservoirs rich in laumontite using the petrology, geochemistry, porosity and permeability characterization, and overburden pressure porosity and permeability tests and further discusses a method for correcting porosity and permeability at normal temperatures and pressures conditions on the ground surface. The reservoir rich in laumontite in the first member of the Shaximiao Formation in the Central Sichuan Basin primarily comprises lithic arkose sandstone, with porosity ranging from 2.12% to 17.48%, with an average of 10.28%, and permeability ranging from 0.004 to 120.351 mD, with an average of 2.691 mD. There are various types of diagenesis, including laumontite cementation, calcite cementation, siliceous cementation, clay mineral cementation, laumontite dissolution, feldspar dissolution, etc. Laumontite is mainly exhibited as pore filling cementation, and the extensive cementation and dissolution of laumontite are the key factors affecting porosity and permeability of reservoirs. By comparing the porosity and permeability difference between overburden pressure condition and normal temperatures and pressures condition, the influence of granular marginal pseudo fractures on the porosity and permeability of the reservoir is corrected. The corrected porosity and permeability values at normal temperatures and pressures conditions on the ground surface are linearly correlated with those before the correction. In different laumontite content intervals, the permeability of the reservoir rich in laumontite accords with the linear correction correlation. The higher the laumontite content, the smaller the correction coefficient is. Therefore, this correction guarantees accurately predict the porosity and permeability of the reservoir rich in laumontite at normal temperatures and pressures conditions on the ground surface.

Isotropic Perfect Fluids in Modified Gravity

We generate the Einstein–Gauss–Bonnet field equations in higher dimensions for a spherically symmetric static spacetime. The matter distribution is a neutral fluid with isotropic pressure. The condition of isotropic pressure, an Abel differential equation of the second kind, is transformed to a first order nonlinear canonical differential equation. This provides a mechanism to generate exact solutions systematically in higher dimensions. Our solution generating algorithm is a different approach from those considered earlier. We show that a specific choice of one potential leads to a new solution for the second potential for all spacetime dimensions. Several other families of exact solutions to the condition of pressure isotropy are found for all spacetime dimensions. Earlier results are regained from our treatments. The difference with general relativity is highlighted in our study.

Experimental and modeling for catechin and epicatechin recovery from peanut skin using subcritical ethanol

AbstractA study on the valorization of peanut (Arachis hypogea) skin as agricultural waste to recover bioactive compounds, including catechin and epicatechin, by subcritical ethanol extraction (SEE) is unexplored scientifically. Thus, this study aims to determine the parameter effects on peanut skin extract recovery by SEE, followed by identifying the semi‐empirical modeling. The best conditions were 6 MPa, 4.53 ml/min, 86.23°C with responses of catechin 188.66 μg/g and epicatechin 336.41 μg/g. High pressure and temperature conditions are conducive to catechin recovery, whereas high pressure with low‐temperature conditions is suitable for epicatechin enhancement. Del Valle Aguilera (DVA) fits the solubility of catechin and epicatechin in SEE effectively compared with the Chrastil model since it has the lowest average absolute relative deviation (AARD), which is 5.97% and 12.69%, respectively. As a result, this approach (SEE) may be used in place of the conventional method for extracting catechin and epicatechin for medicinal purposes.Practical ApplicationSubcritical ethanol extraction (SEE) is more uncomplicated and capable of attaining high extraction rates in a relatively short time to extract catechin and epicatechin from peanut skin. This is because subcritical ethanol rather than subcritical water extraction (SWE) is used to extract catechin and epicatechin from peanut skin at temperatures below 110°C. SEE also employs the lower pressure condition (P < 30 MPa) than SFE. Therefore, SEE is more advantageous than SWE owing to its lower operating conditions, allowing less energy usage. Hopefully, this technology (SEE) may replace the usual technique for extracting catechin and epicatechin for therapeutic uses.

Ocular Surface, Intraocular Pressure, and Lens Condition in Bronchodilator and Steroid-Treated Patients with Chronic Pulmonary Disease

Objectives: The aim of this study was to investigate the ocular surface, intraocular pressure, and lens condition in bronchodilator- and steroid-treated chronic pulmonary disease patients. Methods: In this cross-sectional clinical study, 101 patients with chronic pulmonary disease were treated with an inhaler and/or nebulized therapy for bronchodilatation. The patients were evaluated in 2 groups namely chronic obstructive pulmonary disease and asthma. We investigated the effects of patient demographic characteristics, smoking, and medications on the presence of dry eye disease (DED), intraocular pressure, and cataract. Results: Patients had a mean age of 66.4 ± 11.9 years, and 46.5% (n = 47) were female. A unit increase in the length of inhaled corticosteroids (ICS) and long-acting β-agonists (LABA) combination use was associated with a 1.02-fold increase in cataract risk (OR: 1.02, CI: 1.01–1.04, p = 0.016), and current smokers had 10.8 times as many cataracts (OR: 10.79, CI: 1.70–68.30, p = 0.011). Patients who used a nebulized corticosteroid had a 9.15 times higher risk of developing dry eyes than those who did not (OR: 9.15, CI: 2.34–35.75, p = 0.001). In patients using ICS-LABA, in comparison to formoterol beclomethasone, salmeterol fluticasone was found to increase the risk 7.49-fold for DED (OR: 7.49, CI: 1.48–35.75, p = 0.015). Conclusions: Nebulizer delivery of steroids is associated with dry eyes and cataracts. Smoking, aging, and long-term inhaled steroid use have all been linked to an increased risk of cataracts. Longitudinal and larger sample size studies are needed to explore cause-effect relationships.

中性子回折実験で探る高温高圧下でのSiを含んだhcp鉄の水素化挙動

The identification of light elements in the Earth's core has been an open question for more than 50 years. From seismic observation, the Earth’s core is believed to contain some light elements because it is about 10% less dense than pure Fe at the corresponding pressure and temperature conditions. Among the candidates of light elements in the core, hydrogen is one of the promising light elements. Neutron diffraction is very useful in systems when detecting light atoms surrounded by heavy atoms because its scattering intensity is independent of atomic number. Hence, many neutron diffraction studies have been performed on the iron-hydrogen binary system. On the other hand, it is likely that there is more than one type of light elements dissolved in the core, and interactions between light elements are also involved. Here, we focused on an Fe-Si-H system, and we investigated the sites occupied by deuterium and its site occupancy of hcp Fe0.95Si0.05 Hx at 14.7 GPa and 800 K by in-situ neutron diffraction experiments. So far, this pressure condition is the highest for neutron diffraction experiments at high pressure and high temperature, where crystal structure analysis has been conducted.

Spontaneous intracranial hypotension: a case series and literature review.

Spontaneous intracranial hypotension (SIH) is a condition of negative intracranial pressure resulting from cerebrospinal fluid (CSF) leakage from the dural sac and is a well-known cause of orthostatic headache. Diagnosis and management can be difficult, often requiring coordination between multiple disciplines. Low CSF pressure and diffuse meningeal enhancement on brain MRI are the major instrumental features of the classic syndrome. Neuroimaging plays a key role in diagnosing SIH, particularly in atypical clinical presentations, by recognizing the specific findings of brain sagging on MRI and detecting the level of CSF leak on spinal imaging, thus guiding therapy accordingly. Since SIH could present with such a heterogeneous clinical picture, careful history taking and increased awareness of atypical presentations are of utmost importance. We review the existing SIH literature, illustrate management, clinical and neuroimaging findings of four consecutive patients with atypical SIH, who were recently referred to our hospital for evaluation to simplify and streamline the management of SIH.

Experimental study on influence of forced vibration of cooling channel on heat transfer instability at atmospheric and quasi-critical pressure

Hydrocarbon fuel is used as coolant to cool scramjet by flowing through cooling channels at atmospheric pressure and quasi-critical pressure conditions. The instability of the heat transfer will occur in this process. However, the effect of scramjet vibration on the heat transfer instability is unclear. In order to study the effect of cooling channel forced vibration on the unstable heat transfer performance at trans-crtical pressure, cooling channel heat transfer characteristics under different vibration condition are analyzed. Experimental results show that at atmospheric pressure, cooling channel vibration causes a drastic change in the temperature of the inner wall during unstable heat transfer process, but vibration will not change the fuel bulk temperature oscillation process. As a result, forced vibration can lead to heat transfer deterioration in the gas-liquid two-phase flow. Under the condition of quasi-critical pressure, cooling channel vibration not only change the inner wall temperature, but also influence the fuel bulk temperature. The forced vibration can lead to heat transfer enhancement. High frequency vibration can effectively suppress heat transfer instability and reduces heat transfer fluctuations.

FEATURES OF PLASMA COMPOSITION AND FLUORINE ATOM KINETICS IN CHF3 + O2 GAS MIXTURE

The effects of initial composition of CHF3 + O2 gas mixture on electro-physical plasma parameters, steady-state densities of active species and fluorine atom kinetics were investigated under the condition of constant gas pressure and input power. The combination of plasma diagnostics by Langmuir probes and model-based analysis of plasma chemistry confirmed known from previous work features of plasma composition in the absence of oxygen (in particular, the domination of HF molecules in a gas phase) as well as demonstrated how the oxygen influences steady-state densities of neutral species through kinetics of both electron-impact and atom-molecular reactions. It was shown that the addition of O2 with a proportional decrease in the content of CHF3 a) results in noticeable changes in electrons- and ions-related plasma parameters (electron temperature, electron density, ion flux); b) provides the effective conversion of fluorocarbon radicals (CHFx, CFx) into such compounds as CFxO, FO and COx; and b) causes an increase in the fluorine atom density up to 50% O2. The last phenomenon contradicts with the change in the total F atom formation rate, but reflects a decrease of their loss frequency in the reaction family of CHFx + F → CFx + HF. The model-based analysis of heterogeneous process kinetics was carried out using the set of tracing parameters based on gas-phase plasma characteristics. It was found that the addition of oxygen lowers the plasma polymerizing ability through both decreasing flux of polymerizing species and accelerating the oxidative destruction of deposited polymer film.

Dynamic analysis of grinding electric spindle bearing-rotor system under eccentric action

To study the influence of eccentricity on the dynamic characteristics of grinding electric spindle, firstly, the nonlinear oil film force (NOFF) expression of sliding bearing is established based on the boundary condition of adhesion pressure. Then, the expression of the unbalanced magnetic pull (UMP) under the eccentricity of the air gap is derived. Finally, the bearing-rotor dynamics equation of the grinding electric spindle considering the NOFF and UMP is established, and the dimensionless processing is carried out. The nonlinear dynamics study of the bearing-rotor system under the influence of geometric eccentricity and mass eccentricity is carried out through the shaft center trajectory and the shaft center vibration spectrum. The research results can provide reference for the optimal design of grinding electric spindle.

BALNEOLOGICAL TREATMENT OF PATIENTS WITH LONG COVID-19 SYNDROME IN HEALTH-RESORT CONDITIONS

Aim: The aim of our research was to evaluate the effectiveness of treating patients with Long COVID Syndrome in health-resort conditions. Materials and Methods: 33 patients were qualified for the research. They have all suffered virus infection confirmed by PCR test and met the criteria of Long COVID Syndrome. Course of the acute phase of infection varied among these patients: 22% had mild, 60% moderate and 18% severe symptoms. Patients were treated with our own program including: dietary treatment, kinesiotherapy, balneotherapy, physical therapy and Oxygen therapy. Each patient underwent 5 individually selected therapeutic procedures per day for the period of 14 to 28 days. Each day body temperature, saturation, blood pressure, weight and general clinical condition were monitored. Before and after treatment there was a clinical assessment of physical capacity based on indirect stress test on cycle ergometer, determining general physical capacity level and the maximum capacity of Oxygen absorption (VO2max/l/min.) according to Astrand-Ryhming normogram. Results: statistically significant improvement in clinical condition has been achieved. In case of 10 patients (1/3 of all researched) all syndromes resolved, other patients’ symptoms became fewer and less severe. Differences between average values before and after treatment were statistically significant. In terms of physical capacity a general improvement determined by capacity level was ascertained. 46% of patients researched had initially low or very low capacity level, and after treatment none of them presented the symptoms of low physical capacity. Those patients reached the average physical capacity level. Differences between the average values of VO2max before and after treatment were not statistically significant, which is probably due to little number of patients capable of taking the stress test with the use of cycle ergometer. Conclusions: 1/ Treating patients with Long COVID Syndrome in health-resort conditions is very effective and beneficial, and provides comprehensive therapy of patients with multi-morbidity. 2/ Properly prepared program of treating Long COVID Syndrome allows not only to improve patients’ life quality, but also increases their non-specific immunity, regulates gut microbiome and may help in preventing future infections.

S-12-1: PAST AND FUTURE OF HYPERTENSION RESEARCH

Research on hypertension has achieved, in the last few decades, important results on the pathophysiology, diagnosis and treatment of the high blood pressure (BP) condition. However, as listed in the 2018 European guidelines, several aspects remain unclarified either because they have not been explored by properly designed studies or because data remain controversial. This presentation will discuss some of the questions that represent important unmet needs for hypertension research. One, absence of randomized evidence-based trials on the benefit of antihypertensive treatment in important clinical conditions such as white coat hypertension, masked hypertension, resistant hypertension, hypertension of the very elderly people (e.g. nonagenarians) and hypertensives classifiable as frail because of the high number of comorbidities and poor life expectancy. Two, hypertension of relatively young people (e.g. < 45 or 40 years) in whom low event incidence prevents the performance of event-based trials, making prevention or progression of subclinical organ damage probably the only reliable and feasible approach. Three, the benefit of funding treatment on out-of-office (ambulatory and/or home) BP either as an alternative or an addition to classical office BP reduction, a fundamental therapeutic issue never addressed in the past. Four, the BP threshold at which to start treatment in naive hypertensives and the goal BP value to try to reach in different demographic and clinical hypertension subgroups. And finally, the problem of residual risk in apparently well treated hypertensive individuals, i.e. their persistence at a risk level clearly higher than that of the control population. A final consideration will be that assessing this issue by randomized trials will probably be difficult and that future research will thus have to rely more and more frequently on observational studies which can now be based on large population data-bases that extend over many years and can, via extensive information and high quality analysis, substantially reduce the risk of the risk of confounding associated with this approach.

To issue of evaluation of the influence of external pressure and broken condition of a massif on the blast shattering effect by the smoothed particle hydrodynamics method

To issue of evaluation of the influence of external pressure and broken condition of a massif on the blast shattering effect by the smoothed particle hydrodynamics method

Accurate measurement of trace H<sub>2</sub>S concentration based on cavity ring-down absorption spectroscopy under CO<sub>2</sub>/CO disturbance

Since H<sub>2</sub>S is a corrosive and toxic gas pollutant, the accurate measurement of its concentration is significant. However, in the practical industrial processes, it is difficult to implement because of the disturbance caused by other emissions such as CO<sub>2</sub> and CO. Therefore, in this work, the concentration of H<sub>2</sub>S, CO<sub>2</sub> and CO are measured simultaneously based on cavity ring-down spectroscopy (CRDS) as a viable alternative to measure the concentration of H<sub>2</sub>S accurately when CO<sub>2</sub> and CO exist. First, the wavelength of mixed gas within a range of 6336–6339 cm<sup>–1</sup> is selected as the target region where the spectral line intensity of H<sub>2</sub>S is stronger than 10 times that of CO<sub>2</sub> or CO and the water absorption is extremely weak. Second, the influence of the sampling length (Tm) on the accuracy of the ring-down time is analyzed by evaluating average (accuracy), standard deviation (precision) and consumption time (speed). Third, the experiments are carried out at different pressures in order to obtain the optimal pressure condition. Fourth, the concentration of trace H<sub>2</sub>S is measured when the disturbances caused by CO<sub>2</sub> or CO are added, and the error of the measured concentration is analyzed. Finally, the detection limit of CRDS-based system is calculated to be 6.9 ppb by analyzing the SNR of four groups of low concentration H<sub>2</sub>S spectra, while the lower limit of detection of CRDS-based system is calculated to be 2 ppb by analyzing the Allan variance of long-term data. The measured concentration and its desired value show a good linearity at different dilution ratios. Both the high linearity and the low detection limit of H<sub>2</sub>S indicate the effectiveness of the CRDS-based measurement system to measure H<sub>2</sub>S when CO<sub>2</sub> and CO exist. The successful application of the CRDS-based system to the measurement of H<sub>2</sub>S shows its promising prospect in gas concentration measurement for practical industrial processes.

Effect of external magnetic field on helix plasma plume

<sec>Electric phenomena and magnetic phenomena are inseparable. The magnetic field affects the ionization balance and spatial distribution of the plasma. A new type of plasma discharges has been found in nitrogen gas under sub atmospheric pressure condition without external magnetic field. Because of its regular helical propagation pattern, it is called helical plasma (HP) plume. Although a great deal of research has been carried out on the key characteristics of the HP plume, the formation mechanism of it remains unclear, which affects its applications in materials and nanotechnology.</sec><sec>By applying magnetic field to HP with different chirality, the regulation behavior of the external magnetic field on HP is studied. It is found that the external magnetic field will make the HP shrink or stretch. With the magnetic field intensity increasing from 0 mT to 200 mT, the left-handed HP plume stretches under the magnetic field of S-pole. Conversely, the left-handed chiral HP plume contracts when the magnetic pole changes to N-pole. However, when the chirality of HP plume is changed to being right-handed by adjusting voltage, phenomenon opposite to the previous one is observed. Moreover, the applied magnetic field also affects the divergence of HP. With the increase of S-pole external magnetic field, the HP plume stretches until the external magnetic field reaches to 80 mT. When the magnetic field intensity is 80 mT, the HP disappears. The plasma in the quartz tube appears in the divergent form. With the magnetic field intensity increasing to 160 mT, the plasma in the form of a helix appears again. Finally, in the process of changing the intensity of the magnetic field, the clarity of the HP plume will also change.</sec><sec>The radial electric field of HP is calculated by electromagnetic wave theory, and the mechanism of the influence of external magnetic field on the behavior of HP is clarified. It is found that the magnetic field force component of Lorentz force is responsible for the external magnetic field regulating the HP behavior. This study lays a theoretical foundation for understanding the motion behavior of HP, which is conducive to the practical applications in the field of materials and nanotechnology.</sec>

Confining pressure effect on the permeability and mechanical behavior of sandstone under a certain pore water pressure condition

In geotechnical engineering, the mechanical behavior of rocks under various In-situ conditions (stress state including axial stress, confining pressure, pore water pressure) have always been an important topic. Therefore, the confining pressure effect on the permeability and mechanical behavior of different size sandstone samples under a certain pore water pressure condition was studied. The permeability of different sizes samples shows roughly the same exponential de-creasing law with the increase of confining pressure. In the mechanical behavior test, both the loading Young?s modulus E+ and the unloading Young?s modulus E- increased continuously with increasing confining pressure, while the unloading Poisson's ratio m - decreased to a certain value and then remained almost constant.