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Showing records 3195 to 3219 of 43292. [First] Page: 1 125 126 127 128 129 130 131 132 133 Last
An Optimization-Based Model for A Hybrid Photovoltaic-Hydrogen Storage System for Agricultural Operations in Saudi Arabia
Awsan Mohammed.
June 7, 2023 (v1)
Subject: Optimization
Keywords: hydrogen storage, mixed-integer linear programming, Optimization, photovoltaic system.
Renewable energy technologies and resources, particularly solar photovoltaic systems, provide cost-effective and environmentally friendly solutions for meeting the demand for electricity. The design of such systems is a critical task, as it has a significant impact on the overall cost of the system. In this paper, a mixed-integer linear programming-based model is proposed for designing an integrated photovoltaic-hydrogen renewable energy system to minimize total life costs for one of Saudi Arabia’s most important fields, a greenhouse farm. The aim of the proposed system is to determine the number of photovoltaic (PV) modules, the amount of hydrogen accumulated over time, and the number of hydrogen tanks. In addition, binary decision variables are used to describe either-or decisions on hydrogen tank charging and discharging. To solve the developed model, an exact approach embedded in the general algebraic modeling System (GAMS) software was utilized. The model was validated using a far... [more]
Applications of Terrestrial Laser Scanner in Detecting Pavement Surface Defects
Abdelhalim Azam, Abdulaziz H. Alshehri, Mohammad Alharthai, Mona M. El-Banna, Ahmed M. Yosri, Ashraf A. A. Beshr.
June 7, 2023 (v1)
Keywords: flexible pavement, laser scanner, pavement distress, PCI, plane equation.
An entire roadway system represents a crucial element in the sustainable urban transportation planning process. Pavement surfaces are at continual risk of accumulating serious deteriorations and defects throughout their service life due to traffic loading and environmental impact. Since roadway networks are growing rapidly, relying on visual pavement inspection is not always feasible. Therefore, this paper proposes an effective assessment method for evaluating flexible pavement surface distresses using a terrestrial laser scanner (TLS) and calculating the pavement condition index (PCI). The proposed terrestrial laser scanner method results in road condition assessments becoming faster, safer, and more systematic. It also aims to determine the geometric characteristics of the investigated roads. A major road in Egypt was selected to test the proposed technique and compare it with the traditional visual inspection method. The evaluation was carried out to assess different types of paveme... [more]
Examining Transit-Time Ultrasonic Flowmeter Inaccuracies during Changing Gas Velocity Profiles
Sameh Alsaqoor, Piotr Piechota, Ali Alahmer, Samer As’ad, Nabil Beithu, Wiesław Wędrychowicz, Artur Andruszkiewicz, Patryk Kotomski.
June 7, 2023 (v1)
Keywords: flow measurement, flow stream, measurement error, shape factor, ultrasonic flowmeter.
This study investigates the impact of changes in velocity profiles on the measurement inaccuracies of gas flow streams detected by an ultrasonic flowmeter. The cross-sectional velocity profile was influenced by the downhill flow rate, causing variations in the shape factor coefficient. The flowmeter processing equation should consider the factor of shape coefficient variations. Consideration for these variations can result in errors in the measurement of the flow stream. The processing equation assumes a single, constant value for the shape factor coefficient, which can lead to inaccuracies. This article covers the inaccuracies of the transit-time ultrasonic flowmeter caused by a change in the velocity profile of the flowing gas, such as air. A realistic flow system was established with measured flow rates ranging from 43 m3/h to 225 m3/h. The findings of this study can serve as a valuable reference for the design and implementation of more accurate and efficient flow measurement syste... [more]
Computational Study of Security Risk Evaluation in Energy Management and Control Systems Based on a Fuzzy MCDM Method
Wajdi Alhakami.
June 7, 2023 (v1)
Keywords: communication network, multiple criteria decision-making, power control system, security evaluation, security risk.
Numerous cyberattacks on connected control systems are being reported every day. Such control systems are subject to hostile external attacks due to their communication system. Network security is vital because it protects sensitive information from cyber threats and preserves network operations and trustworthiness. Multiple safety solutions are implemented in strong and reliable network security plans to safeguard users and companies from spyware and cyber attacks, such as distributed denial of service attacks. A crucial component that must be conducted prior to any security implementation is a security analysis. Because cyberattack encounters in power control networks are currently limited, a comprehensive security evaluation approach for power control technology in communication networks is required. According to previous studies, the challenges of security evaluation include a power control process security assessment as well as the security level of every control phase. To address... [more]
Residential Buildings Heating and Cooling Systems: The Key Role of Monitoring Systems and Real-Time Analysis in the Detection of Failures and Management Strategy Optimization
Giovanna Cavazzini, Alberto Benato.
June 7, 2023 (v1)
Keywords: buildings energy efficiency, full electric buildings, heat pumps, natural gas boilers.
Nineteen percent of global final energy consumption is used to generate electricity and heat in buildings. Therefore, it is undisputed that the building sector needs to cut consumption. However, this reduction needs to be driven by data analysis from real building operations. Starting from this concept and with the aim of proving the benefits deriving from the installation of a monitoring system in a real operating environment, in this work a monitoring system has been installed to monitor the centralised heating and cooling system of a residential building composed of 57 residential units. The data acquired from the installed sensors are collected and subsequently analysed in an ad hoc tool to detect anomalies, performance decay, malfunctions, and failures of the machines, as well as to understand if the implemented management strategy is appropriate in terms of energy and cost savings. The results show the key role of the data acquired by the monitoring system and analysed by the dev... [more]
Influence of Internal Structural Parameters on the Inner Flow and Outer Spray Characteristics for Feedback-Free Fluidic Oscillator
Zhijun Wu, Pengfei Leng, Yu Gao, Wenbo Zhao, Zongjie Hu, Xiangxiang Lu, Rongzhu Shi, Wei Xie, Liguang Li.
June 7, 2023 (v1)
Subject: Other
Keywords: feedback-free fluidic oscillator, internal flow, spray characteristics, structural parameters.
Feedback-free fluidic oscillators, relying on the interaction of jets to oscillate, have a wide range of operation frequencies and no moving parts, which is promising for future applications. In this paper, the sweep angle, oscillation frequency, and volume flow rate of the feedback-free fluidic oscillator with a cavity width of 4.6 mm were measured experimentally, and the sweeping mechanism was analyzed based on the internal flow simulation. The influence of the impact angle, cavity exit width, and shoulder radius on the internal flow and external spray characteristics was analyzed by the numerical method. The results show that the sweep angle and oscillation frequency are affected throughout the increase in impact angle from 80° to 120°. However, only when the SR is greater than 0.88 mm does the internal flow and spray state change significantly. The volume flow rate is mainly affected by the cavity exit width and increases linearly from 5.3 mL/s to 9.3 mL/s as the width increases fr... [more]
DEM Simulation of a Rotary Drum with Inclined Flights Using the Response Surface Methodology
Xu Zhu, Lixin Xie, Shichang Xu, Wen Zhang.
June 7, 2023 (v1)
Keywords: axial motion, beads, DEM, inclined flight, particle distribution, response surface methodology, rotary drum dryer.
Conventional flighted rotary drums usually have flights parallel to the rotating axis, which cannot facilitate the axial motion of the materials in the drum. Here, a new type of horizontal rotary drum with inclined flights and beads was designed. Inclined flights are used to facilitate the axial movement of beads and material, while beads are used as fillers to increase the gas-liquid contact area and to crush the solid materials. We simulated the drum and studied the axial motion of fillers using the discrete element method (DEM). To improve the mass and heat transfer performance, we optimized the distribution of beads in the active phase. The effects of the rotational speed, joint angle, and inlet flow rate in the drum were investigated systematically. The individual effects were evaluated in terms of the mass of particles in the active phase (MAP) and passive phase (MPP), the percentage of the active phase occupied by the particles (OAR), and the axial speed (AS). The response surfa... [more]
Denaturation and Digestion Increase the Antioxidant Capacity of Proteins
Kacper Kut, Grzegorz Bartosz, Izabela Sadowska-Bartosz.
June 7, 2023 (v1)
Subject: Biosystems
Keywords: antioxidant capacity, bovine serum albumin, denaturation, egg white proteins, papain, protein, trypsin.
It has been estimated and demonstrated that the antioxidant capacity of proteins is increased as a result of digestion in the gastrointestinal tract, which can be contributed by denaturation and digestion. This study aimed to evaluate the effect of denaturation and proteolytic digestion on the antioxidant activity of bovine serum albumin (BSA) and chicken egg white proteins in model systems. Denaturation with an anionic detergent (sodium dodecyl sulfate) and digestion with papain and trypsin increased the antioxidant activity/capacity of the proteins, apparently due to the increased exposure of amino acid residues responsible for the antioxidant activity of proteins (tyrosine, tryptophan, cysteine, histidine, arginine, and cystine in the ABTS● decolorization assay; cysteine, tryptophan, tyrosine, and cystine in the FRAP assay). As the increase in the protein antioxidant activity/capacity was limited in extent, it does not invalidate the use of the antioxidant capacity of proteins to be... [more]
Experimental Study on Ratio Optimization of Similar Materials for Underground Mining of Shendong Coalfield: A Case Study of Shangwan Coal Mine
Yingming Yang, Hao Yue, Yongqiang Zhao, Shen Zhang, Jian Zhang, Zhaohui Wang, Wenqiang Yang.
June 7, 2023 (v1)
Subject: Materials
Keywords: mechanical properties, orthogonal experimental design, physical simulation, sensitivity analysis, similar material proportion.
Physical simulation is one of the effective methods to study mining problems, but the selection and proportion of simulation materials are greatly affected by the regional environment. This paper is based on a multilevel orthogonal design test scheme using sand, lime, and gypsum as the materials in the Shangwan coal mine in the Shendong coalfield, with the sand to cement ratio, paste to ash ratio, and maintenance days as variables. The effect of the polar difference method on the strength and density of gypsum was used as a reference for physical simulation in the Shendong coalfield. The sensitivity analysis of each factor was carried out by the polar difference method, and the influencing factors on density were, in descending order, sand to mortar ratio, mortar to ash ratio, and the number of maintenance days; the influencing factors on strength were, in descending order, mortar to ash ratio, maintenance days, and sand to mortar ratio. The sand cement ratio was negatively correlated... [more]
Physical Properties of Moist, Fermented Corn Kernels
Keagan J. Blazer, Kevin J. Shinners, Zachary A. Kluge, Mehari Z. Tekeste, Matthew F. Digman.
June 7, 2023 (v1)
Keywords: corn, density, fermented, flow, friction, kernels, properties, repose.
A novel approach to producing corn stover biomass feedstock has been investigated. In this approach, corn grain and stover are co-harvested at moisture contents much less than typical corn silage. The grain and stover are conserved together by anaerobic storage and fermentation and then separated before end use. When separated from the stover, the moist, fermented grain had physical characteristics that differ from typical low-moisture, unfermented grain. A comprehensive study was conducted to quantify the physical properties of this moist, fermented grain. Six corn kernel treatments, either fermented or unfermented, having different moisture contents, were used. Moist, fermented kernels (26 and 36% w.b. moisture content) increased in size during storage. The fermented kernels’ widths and thicknesses were 10% and 15% greater, respectively, and their volume was 28% greater than the dry kernels (15% w.b.). Dry basis particle density was 9% less for moist, fermented kernels. Additionally,... [more]
Editorial Overview of the Special Issue “Biological Activity Evaluation Process of Natural Antioxidants”
Chang-Wei Hsieh, Jer-An Lin.
June 7, 2023 (v1)
We are glad to share the editorial summary of the Special Issue on "Biological Activity Evaluation Process of Natural Antioxidants," edited by Chang-Wei Hsieh and Jer-An Lin of National Chung Hsing University [...]
Effects of Deep Cryogenic Treatment and Controlled Rolling on Microstructures and Mechanical Properties of an Ultra-High Strength Steel
Yongli Chen, Xuejiao Zhou, Yuhua Li, Fei Tan.
June 7, 2023 (v1)
Subject: Materials
Keywords: deep cryogenic, refinement strengthening, retained austenite, rolling, strain gradient, ultra-high strength steel.
The microstructure mechanisms and mechanical properties of 0.23C-1.96Si-1.94Cr-1.93 Mn-0.35 Mo ultra-high strength steel treated by the deep cryogenic treatment at −196 °C were investigated after the steel was hot rolled at different temperatures. Experimental results show that austenitizing zone rolling with a large reduction in a single pass can comprehensively enhance the mechanical properties due to the high volume of retained austenite and refined lath martensite and bainite. The high strain gradient was suppressed, and tensile strength, yield strength, impact toughness, and total elongation were 2221 MPa, 2017 MPa, 65.5 J, and 16.9%, respectively. In addition, the austenitizing zone rolling can promote the formation of film retained austenite more than dual phase zone rolling, and retained austenite was decreased with an increase in rolling pass in a total rolling reduction of 75%. It is demonstrated that deep cryogenic treatment after austenite zone rolling with a large reductio... [more]
Control Mechanism of Microbial Degradation on the Physical Properties of a Coal Reservoir
Daping Xia, Pengtao Gu, Zhenhong Chen, Linyong Chen, Guoqin Wei, Zhenzhi Wang, Song Cheng, Yawei Zhang.
June 7, 2023 (v1)
Subject: Biosystems
Keywords: coal pore structure, diffusion, dual effect, microbial yield, pore connectivity.
This study addressed the effect of microbial methane production on the physical properties of a coal reservoir. Two kinds of coal samples before and after anaerobic degradation were tested by a low-temperature liquid nitrogen adsorption test and an isothermal adsorption and diffusion coefficient test. The influence of the characteristics of microbial gas production on the coal physical properties was analyzed. Due to the differences in the physical properties of the coal samples, the effect of microbial production is different. Coal is a macromolecular organic compound, mainly aromatic and lignin derivatives, containing carbon and nitrogen sources that can be used by microorganisms. Microorganisms secrete extracellular enzymes to decompose covalent bonds and functional groups of macromolecules in coal and eventually produce methane, which will change the physical properties of coal. It was found that microbial anaerobic degradation could increase the content of coalbed methane, change... [more]
Food Waste (Beetroot and Apple Pomace) as Sorbent for Lead from Aqueous Solutions—Alternative to Landfill Disposal
Tatjana Šoštarić, Marija Simić, Zorica Lopičić, Snežana Zlatanović, Ferenc Pastor, Anja Antanasković, Stanislava Gorjanović.
June 7, 2023 (v1)
Keywords: apple pomace, beetroot pomace, lead sorption, organic waste.
This article presents studies, whose main goal was to minimize food waste. To achieve this goal, it is necessary to expand the scope of their application, for example, for the purification of polluted water from heavy metals. Millions of tons of waste from the fruit and vegetable industry, including pomace of apples and beetroots, are thrown into landfills, posing a danger to the environment. In order to solve the problems with the disposal of these wastes, the authors investigated their sorption potential for the removal of lead from wastewater. The sorbents, dried apple (AP), and beetroots (BR) pomaces were characterized by various methods (study of composition, zeta potential, FTIR-ATR, and SEM-EDX). Various models of sorption kinetics and sorption isotherms were analyzed. Kinetical studies under optimal conditions showed that the sorption process occurs through complexation and ion exchange and the determining stage limiting the rate of sorption is the diffusion of lead ions in the... [more]
Integration of Multiple Bayesian Optimized Machine Learning Techniques and Conventional Well Logs for Accurate Prediction of Porosity in Carbonate Reservoirs
Saad Alatefi, Reda Abdel Azim, Ahmad Alkouh, Ghareb Hamada.
June 7, 2023 (v1)
Keywords: carbonate reservoirs, Gaussian process regression, least squares gradient boosting ensemble, machine learning techniques, porosity AI-based correlation.
The accurate estimation of reservoir porosity plays a vital role in estimating the amount of hydrocarbon reserves and evaluating the economic potential of a reservoir. It also aids decision making during the exploration and development phases of oil and gas fields. This study evaluates the integration of artificial intelligence techniques, conventional well logs, and core analysis for the accurate prediction of porosity in carbonate reservoirs. In general, carbonate reservoirs are characterized by their complex pore systems, with the wide spatial variation and highly nonlinear nature of their petrophysical properties. Therefore, they require detailed well-log interpretations to accurately estimate their properties, making them good candidates for the application of machine learning techniques. Accordingly, a large database of (2100) well-log records and core-porosity measurements were integrated with four state-of-the-art machine learning techniques (multilayer perceptron artificial ne... [more]
Deep Learning Based Methods for Molecular Similarity Searching: A Systematic Review
Maged Nasser, Umi Kalsom Yusof, Naomie Salim.
June 7, 2023 (v1)
Keywords: deep learning, drug design, drug discovery, molecular similarity searching, virtual screening.
In rational drug design, the concept of molecular similarity searching is frequently used to identify molecules with similar functionalities by looking up structurally related molecules in chemical databases. Different methods have been developed to measure the similarity of molecules to a target query. Although the approaches perform effectively, particularly when dealing with molecules with homogenous active structures, they fall short when dealing with compounds that have heterogeneous structural compounds. In recent times, deep learning methods have been exploited for improving the performance of molecule searching due to their feature extraction power and generalization capabilities. However, despite numerous research studies on deep-learning-based molecular similarity searches, relatively few secondary research was carried out in the area. This research aims to provide a systematic literature review (SLR) on deep-learning-based molecular similarity searches to enable researchers... [more]
Theory and Application of Geostatistical Inversion: A Facies-Constrained MCMC Algorithm
Wenbo Dong, Yonggen Li, Zhixian Gui, Lei Zhou.
June 7, 2023 (v1)
Subject: Other
Keywords: facies-constrained inversion, geostatistics, reservoir prediction, seismic inversion, special reservoir, thin reservoir prediction.
To improve the prediction of thin reservoirs with special geophysical responses, a geostatistical inversion technique is proposed based on an in-depth analysis of the theory of geostatistical inversion. This technique is based on the Markov chain Monte Carlo algorithm, to which we added the contents of facies-constrained. The feasibility of the technique and the reliability of the prediction results are demonstrated by a prediction of the sand bodies in the braided river channel bars in the Xiazijie Oilfield in the Junggar Basin. Based on the MCMC algorithm, the results show that leveraging the lateral changes in the seismic waveforms as geologically relevant information to drive the construction of the variogram and the optimization of the statistical sampling can largely overcome the obstacle that prevents traditional geostatistical inversions from accurately delineating the sedimentary characteristics; thereby, the proposed algorithm truly achieves facies-constrained geostatistical... [more]
Ethanolic Leaves Extract Mediates Inhibition of NF-κB Signaling Pathway in Lung Adenocarcinoma A549 Cells
Gehad Subaiea, Ahmed Alafnan, Abdulwahab Alamri, Talib Hussain, Shimaa Mahmoud Hassoun, Amr Selim Abu Lila, El-Sayed Khafagy, Ahmed A. Katamesh.
June 7, 2023 (v1)
Subject: Biosystems
Keywords: A549, apoptosis, Coleus aromaticus extract, NF-κB, non-small cell lung carcinoma, ROS.
Lung cancer is the second leading cause of cancer-related mortalities globally. Failure in diagnosis at early stages and limited effective chemotherapeutics has severely impeded the clinical management of patients suffering from lung carcinoma. At present, researchers across the world are focused on exploring biologically active natural products for treating various cancers, which can thus be further investigated for their chemotherapeutical potential. Coleus aromaticus is a common herb used in culinary practices and has previously been shown to possess various medicinal characteristics. In the present study, the anti-cancer effects of ethanolic extract of C. aromaticus leaves (EtOH-LCa) against non-small cell lung carcinoma (NSCLC) A549 cells were screened. It was observed that EtOH-LCa reduced the viability of A549 cells and obstructed the cell cycle progression in a concentration-dependent manner. Importantly, EtOH-LCa succeeded in instigating the production of reactive oxygen speci... [more]
Emergency Material Scheduling Optimization Method Using Multi-Disaster Point Distribution Approach
Mengying Chang, Huizhi Xu, Dongsheng Hao, Jinhuan Zhou, Chen Liu, Chujie Zhong.
June 7, 2023 (v1)
Keywords: emergency dispatch, epidemic prevention and control, logistics engineering, multi-distribution center problem, TOPSIS decision.
The outbreak of multiple disaster sites during the coronavirus disease 2019 (COVID-19) pandemic has presented challenges due to varying access time intensity, population density, and medical resources at each site. To address these issues, this study focuses on 13 districts and counties in Wuhan, China. The importance of each research area is analyzed using the improved PageRank and TOPSIS algorithms to determine the optimal site selection plan. Additionally, a particle swarm algorithm is used to construct an emergency material dispatching model that targets both distribution and site selection costs to solve the multi-distribution center dispatching problem. The results suggest that constructing 10 distribution centers can satisfy the demand for epidemic prevention and control in Wuhan city while saving costs associated with site selection and material distribution. Compared to the previous optimal solution, the distribution and site selection costs under the optimal solution decrease... [more]
Evaluation of Adsorption Efficiency on Pb(II) Ions Removal Using Alkali-Modified Hydrochar from Paulownia Leaves
Marija Koprivica, Marija Simić, Jelena Petrović, Marija Ercegović, Jelena Dimitrijević.
June 7, 2023 (v1)
Subject: Materials
Keywords: adsorption mechanism, alkali modification, biowaste hydrochar, kinetics and isotherm models, lead removal.
In this study, hydrothermal carbonization (HTC) at five temperatures (180, 200, 220, 240, and 260 °C) was applied to transform Paulownia leaves (PL) into a carbonaceous sorbent of Pb(II) from aqueous solutions. To enhance the adsorption efficiency of the obtained hydrochar (PH), subsequent alkali activation was performed using NaOH. Preliminary results of the Pb(II) adsorption (CPb = 200 mg/L) showed removal coefficients after 48 h of 73.44 mg/g, 82.37 mg/g, and 110.9 mg/g for PL, PH-220, and MPH-220, respectively. The selected hydrochar (PH-220) and modified hydrochar (MPH-220) were further investigated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results revealed that alkali treatment changed the hydrochar structure and, thus, improved its adsorption performance. The kinetic parameters showed that the Pb(II) sorption onto MPH-220 followed a pseudo-second-order model, while the intra-particle diffusion went through two simultaneous stag... [more]
Influence of Wall Heat Effect on Gas Explosion and Its Propagation
Zhenzhen Jia, Qing Ye, Zhuohua Yang.
June 7, 2023 (v1)
Keywords: gas explosion, heat loss, numerical simulation, wall heat effect.
The gas explosion process in pipes is often accompanied by an intense wall heat effect. A considerable part of the explosion energy is dissipated, and the process of gas explosion and its propagationis affected. In order to study the influence of wall heat effect on gas explosion and its propagation, numerical models of gas explosion in pipes with different adiabatic degrees were established by ANSYS/LS-DYNA. The propagation process of gas explosion in pipes under the influence of the wall heat effect was numerically simulated and analyzed, and the thermal stress and temperature distribution of pipes with different adiabatic degrees were studied. The results show that with a decrease in pipe insulation, the wall heat effect increases, the heat loss of gas explosion increases, and the overpressurizationof the shock wave, the explosion intensity, and the thermal stress of the pipe wall are significantly reduced. The results indicate that the wall heat effect can weaken the gas explosion... [more]
Optimization and Control of Propylene Production by Metathesis of 2-Butene
Andrei Maxim Andrei, Costin Sorin Bildea.
June 7, 2023 (v1)
Keywords: dynamic simulation, flowsheeting, olefin metathesis, process control, process design, propylene production, safety.
This article considers the design and control of the 2-butene metathesis process. The process transforms a low-value feedstock derived from a fluid catalytic cracking unit into more valuable products. The economical optimization is applied to the preheat−reaction and separation sections, with the objective of minimizing the total annual cost. The dynamic response and control of the plant are evaluated for feed flow perturbations. Although the process control system acts as a first line of defense against potential hazards, other independent safety layers are discussed with safety limits specific to the critical equipment of the 2-butene metathesis unit. The results prove that the metathesis reaction of 2-butene over a mesoporous tungsten catalyst is economically attractive. For a 5.7 t/h feed rate consisting of 2-butene (70% molar) and n-butane (30% molar), a reaction−separation plant (without recycle) requires 6570 × 103 $ investment and has a profitability of 2300 × 103 $/year.
Chemical Composition of the Essential Oil of Catha edulis Forsk from Djibouti and Its Toxicological Investigations In Vivo and In Vitro
Fatouma Mohamed Abdoul-Latif, Ayoub Ainane, Ibrahim Houmed Aboubaker, Ali Merito Ali, Zineb El Montassir, Mateusz Kciuk, Jalludin Mohamed, Tarik Ainane.
June 7, 2023 (v1)
Subject: Biosystems
Keywords: antibacterial activity, biochemical tests, biological activities, Catha edulis Forsk, chemical composition, essential oil, hematology, toxicity.
This work aimed to evaluate the chemical composition of essential oils from Catha edulis Forsk collected in the Day Forest of the Republic of Djibouti. Additionally, in vivo toxicity studies, biochemical profiling, and hematological tests were conducted to determine the biological activity of the investigated essential oils. Finally, in vitro tests were performed to investigate the antibacterial activity of the essential oils. The essential oils were obtained at yields of 0.75%. Chromatographic analysis identified 39 compounds, of which cathinone (81.4%) and cathine (10.55%) were determined as the two major components, representing 91.95% of the total composition. Catha edulis essential oil had a rat LD50 of 2500 mg/kg, indicating very low toxicity. Chronic exposure studies revealed that use of the essential oil in rats resulted in persistent stimulant action at dosages of 100 and 200 mg/kg, whereas the weight gain of control rats was faster than that of the essential oil-treated rats.... [more]
The Development and Application of Novel Water-Based Drilling Fluid for Complex Pressure System Formation in the South China Sea
Hexing Liu, Yi Huang, Zhiqin Liu, Lifei Dong, Miao Wang.
June 7, 2023 (v1)
Subject: Other
Keywords: complex pressure system, loss-circulation, pressure bearing capacity, reservoir protection, water-based drilling fluid.
The Y oilfield reservoir is characterized by ultra-depleted reservoir and multiple pressure systems in each well section. If conventional PLUS/KCL drilling fluid is used in directional drilling, the following problems are found: the rheological stability of drilling fluid is not sufficient, resulting in increased viscosity and thickening after aging, and the single plugging material may cause loss-circulation when the drilling differential pressure is more than 26 MPa, resulting in poor reservoir protection effects. To solve the above problems, based on the conventional PLUS/KCL drilling fluid formula, a PLUS/KCL drilling fluid system suitable for directional drilling in multi-pressure systems was formed by optimizing the addition of a treating agent to improve the rheological stability of the drilling fluid, optimizing the plugging agent and compound combination to improve plugging ability, and optimizing the particle size distribution of a temporary plugging agent to improve the rese... [more]
A Facile Hydrothermal Synthesis of S-VO2-Cellulose Nanocomposite for Photocatalytic Degradation of Methylene Blue Dye
Mostafa Y. Nassar, Mona S. NourEldien, Islam M. Ibrahim, Hisham M. Aly.
June 7, 2023 (v1)
Subject: Materials
Keywords: methylene blue, microcrystalline cellulose, nanocomposite, photocatalytic degradation, vanadium dioxide.
A novel UV-light-active MCC/S-VO2 photocatalyst was successfully synthesized by a simple and reliable hydrothermal route. XRD, FT-IR, Raman analysis, XPS, FE-SEM, EDX, TEM, DRS, and thermal analysis techniques were utilized for the characterization of the as-prepared photocatalysts. The photocatalytic activities of the V2O5, doped S-VO2, and MCC/S-VO2 nanostructures were investigated by monitoring the fading out of the methylene blue (MB) concentration under UV-light irradiation. The results revealed that the photocatalytic degradation of MB via MCC/S-VO2 was superior compared with that exhibited by pure V2O5 and doped S-VO2. It was found that 72.3% of MB (100 mL; 20 mg·L−1) was degraded after 6 h in contact with MCC/S-VO2. Interestingly, the photodegradation of MB dye was enhanced dramatically by adding H2O2, while 92.5% of MB was degraded within 55 min. The kinetic studies revealed that the MB degradation followed the pseudo-first-order model with a rate constant (kobs) of 3.9 × 10−2... [more]
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