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Showing records 36825 to 36849 of 43292. [First] Page: 1 1470 1471 1472 1473 1474 1475 1476 1477 1478 Last
Recovery of Mineral Wool Waste and Recycled Aggregates for Use in the Manufacturing Processes of Masonry Mortars
Daniel Ferrández, Manuel Álvarez, Pablo Saiz, Alicia Zaragoza-Benzal
February 21, 2023 (v1)
Subject: Materials
Keywords: construction and demolition waste, mineral wool, mortar, recycled aggregates
The environmental problems caused by industrial waste are of a universal nature. In this sense, achieving an adequate management of construction and demolition waste has become one of the great challenges of today’s society. This work studies the possibility of recovering mineral wool thermal insulation waste for its reincorporation into the manufacturing process of masonry mortar. To this end, an experimental campaign has been conducted with mortars made with natural aggregate and two types of recycled aggregates: concrete and mixed ceramic, in which mineral wool fibers are incorporated as a partial replacement of sand in percentages of 0%, 10% and 20%. The results show that, although the traditional mortars offer better technical performance, the mortars made with recycled aggregate present adequate viability for use on-site. Furthermore, it has been concluded that the incorporation of recycled mineral wool fibers in the mortar matrix decreases the thermal conductivity and shrinkage... [more]
Impact of Biogenic Ag-Containing Nanoparticles on Germination Rate, Growth, Physiological, Biochemical Parameters, and Antioxidants System of Tomato (Solanum tuberosum L.) In Vitro
Abdalrhaman M. Salih, Ahmed A. Qahtan, Fahad Al-Qurainy, Bander M. Al-Munqedhi
February 21, 2023 (v1)
Subject: Materials
Keywords: Ag-containing nanoparticles, antioxidants, nano-fertilizer, phenolic compounds
Tomatoes (Solanum tuberosum L.) are considered one of the most effective and nutritious foods in the human diet. Moreover, the fruit of a tomato is rich in phytochemical compounds such as carotenoids, vitamins, and phenolics which are beneficial to human health. The objective of this present research was to investigate the impact of biogenic Ag-containing nanoparticles on seed germination rate and germination speed index, the development of the stem and root system, and physio-biochemical parameters. Ag-containing nanoparticles were synthesized biologically using a silver nitrate solution and aqueous seed extract of Juniperus procera, which acted as a capping and reducing agent. The impact of different concentrations (0.0, 2.5, 5, 10, and 25 mg/L) of Ag-containing NPs on seed germination rate, biomass accumulation, phenolic compounds, total protein, enzymes activity, and total soluble sugar of tomatoes (Solanum tuberosum L.) in vitro has been tested. The obtained result demonstrated th... [more]
Design, Implementation and Simulation of a Small-Scale Biorefinery Model
Mihaela Sbarciog, Viviane De Buck, Simen Akkermans, Satyajeet Bhonsale, Monika Polanska, Jan F. M. Van Impe
February 21, 2023 (v1)
Keywords: Biomass, biorefinery design, process integration, Scheduling, Simulation
Second-generation biomass is an underexploited resource, which can lead to valuable products in a circular economy. Available locally as food waste, gardening and pruning waste or agricultural waste, second-generation biomass can be processed into high-valued products through a flexi-feed small-scale biorefinery. The flexi-feed and the use of local biomass ensure the continuous availability of feedstock at low logistic costs. However, the viability and sustainability of the biorefinery must be ensured by the design and optimal operation. While the design depends on the available feedstock and the desired products, the optimisation requires the availability of a mathematical model of the biorefinery. This paper details the design and modelling of a small-scale biorefinery in view of its optimisation at a later stage. The proposed biorefinery comprises the following processes: steam refining, anaerobic digestion, ammonia stripping and composting. The models’ integration and the overall b... [more]
Coal Pillar Stress Weakening Technology and Application by Gob-Side Entry Driving and Hydraulic Roof Cutting in Deep Shafts Mines
Zhi Zhang, Jianguo Ning, Jun Wang, Kun Wang, Shang Yang, Ruyu Yan, Guoqing Sun, Minghao Du
February 21, 2023 (v1)
Keywords: gob-side entry driving, hydraulic roof cutting, industrial practice, pressure relief effect
To solve the problems of serious deformation and support difficulty of deep and narrow gob-side coal pillars, an optimized hydraulic roof cutting structural model for the roof structure of narrow gob-side coal pillars in kilometer−deep shafts was established based on the 6302 working face of the Xinhe coal mine. The influence of factors such as the angle and height of hydraulic roof cutting on the stress evolution of narrow gob-side coal pillars was analyzed, the principle of the pressure relief of hydraulic roof cutting of narrow gob-side coal pillars in kilometer−deep shafts was revealed, and an industrial application was conducted. The results of the study show that, first, the hydraulic roof cutting of narrow gob-side coal pillars in a kilometer−deep shaft transfers the roof load only to the gob area, but not to the solid-side deep coal body; and second, there is an optimal height for roof cutting and pressure relief, i.e., the effect of roof cutting and pressure relief will not be... [more]
Electroreduction of CO2 toward High Current Density
Jing Lin, Shenglin Yan, Chunxiao Zhang, Qing Hu, Zhenmin Cheng
February 21, 2023 (v1)
Keywords: challenges and perspectives, CO2 electroreduction, electrocatalysts, electrolytes, electrolyzers, high current densities, long-term operations
Carbon dioxide (CO2) electroreduction offers an attractive pathway for converting CO2 to valuable fuels and chemicals. Despite the existence of some excellent electrocatalysts with superior selectivity for specific products, these reactions are conducted at low current densities ranging from several mA cm−2 to tens of mA cm−2, which are far from commercially desirable values. To extend the applications of CO2 electroreduction technology to an industrial scale, long-term operations under high current densities (over 200 mA cm−2) are desirable. In this paper, we review recent major advances toward higher current density in CO2 reduction, including: (1) innovations in electrocatalysts (engineering the morphology, modulating the electronic structure, increasing the active sites, etc.); (2) the design of electrolyzers (membrane electrode assemblies, flow cells, microchannel reactors, high-pressure cells, etc.); and (3) the influence of electrolytes (concentration, pH, anion and cation effec... [more]
Feasibility of a Complex Optimized Process for the Treatment of Patients Receiving Hip and Knee Endoprostheses in Most Different Settings in Germany—Results from the PROMISE Trial
Ulrich Betz, Laura Langanki, Florian Heid, Lukas Schollenberger, Kai Kronfeld, Matthias Büttner, Britta Büchler, Lukas Eckhard, Thomas Klonschinski, Philipp Drees
February 21, 2023 (v1)
Subject: Optimization
Keywords: ERAS, feasibility, hip replacement, knee replacement, process optimization
Background: While there is evidence on the effectiveness of optimized treatment processes for patients receiving hip and knee endoprostheses, feasibility in various settings has not been adequately investigated. The multicenter PROMISE Trial (Process optimization by interdisciplinary and cross-sectoral care using the example of patients with hip and knee prostheses) was set up to fill this gap. Methods: A complex optimized process was implemented in three German hospitals offering different levels of care and five cooperating rehabilitation centers. For the feasibility question, data on 19 parameters characterizing the defined process were collected. The extent of cross-sectoral collaboration was a special focus. Results: The data show, for almost all parameters in all facilities, an implementation rate of more than 80% with missing data below 5%, n = 1887 study participants. A total of 96.8% attended a rehabilitation program, and for 29.2% rehabilitation took place in a PROMISE-collab... [more]
Reduced Use of Nitrites and Phosphates in Dry-Fermented Sausages
Martin Škrlep, Manja Ozmec, Marjeta Čandek-Potokar
February 21, 2023 (v1)
Subject: Materials
Keywords: additives, ascorbates, dry sausages, nitrites, phosphates
Given consumer demand for foods with fewer artificial additives, the objective of this study was to investigate the effects of reduced use of nitrites and phosphates on dry-fermented sausage quality. Four sausage formulations were prepared: (1) control (using standard procedure with 0.2% phosphates and 110 mg/kg sodium nitrite) and formulations with (2) 50% less sodium nitrite, (3) 50% less sodium nitrite and sodium ascorbate (225 mg/kg), and (4) with standard nitrite but no phosphates. Weight loss and pH evolution were monitored during processing. The color, physicochemical (including oxidation), rheological, and sensory properties were evaluated on the finished product, as well as mold growth and microbiological status. Compared to control, nitrite reduction was associated with increased surface mold growth, reduced (3.0−4.4%) processing loss, and slightly higher oxidation (1.7 μg/kg more malondialdehyde) but without affecting instrumental color. The simultaneous addition of ascorbat... [more]
Heavy Metal Distribution in Surface Sediments of the Coastal Pearl Bay, South China Sea
Changping Yang, Gang Yu, Yan Liu, Binbin Shan, Liangming Wang, Dianrong Sun, Yingbang Huang
February 21, 2023 (v1)
Keywords: ecological risk assessment, heavy metals, Pearl Bay, surface sediment
Six heavy metals (As, Cu, Cd, Zn, Cr, and Pb) in surface sediments (0−5 cm) from the twenty selected sites of the coastal Pearl Bay (South China Sea) were analyzed to assess the distribution pattern and potential ecological risk. Overall concentrations (mg/kg, dw) in the sediment samples were: As (10.88 ± 6.50), Cu (24.16 ± 18.63), Cd (0.55 ± 0.78), Zn (48.53 ± 30.06), Cr (35.78 ± 28.66), Pb (31.28 ± 18.50). Results showed that the overall mean values of Cd concentrations exceeded the standard of China Marine Sediment Quality, caused by significantly high levels of Cd contents in five sites (S8, S11, S13, S16, and S17) at the offshore area of Pearl Bay. Generally, the metal concentrations showed a decreasing trend from the offshore area to the inner bay. Various index values such as the geo-accumulation index (Igeo), the ecological risk index (Eri), and the contamination factor (CF) demonstrated that the coastal Pearl Bay was not polluted by the examined metals except for Cd, which mig... [more]
Effects of Modified Biochar on the Mobility and Speciation Distribution of Cadmium in Contaminated Soil
Liwen Zheng, Hongying Ji, Yongchao Gao, Zhongfeng Yang, Lei Ji, Qingqing Zhao, Yanju Liu, Xiangliang Pan
February 21, 2023 (v1)
Subject: Materials
Keywords: bioavailability, biochar, Cd-contaminated soil, in situ immobilization, speciation
Cadmium-contaminated soil poses a threat to the environment and human health. Biochar materials have received widespread attention as an in situ immobilizer for the efficient remediation of heavy-metal-contaminated soils. In this study, a modified biochar material (E−CBC) was developed for the immobilization of Cd in contaminated soil. E−CBC was characterized by XPS, SEM, BET, and FTIR. The effects of pristine biochar (BC) and E−CBC on soil physicochemical properties (pH and soil organic matter (SOM)), CaCl2-extractable Cd, total characteristics leaching procedure (TCLP) Cd, and speciation distribution of Cd were studied by incubation experiments. The results showed that the application of BC and E−CBC increased soil pH slightly and SOM significantly. A 2% dosage BC and E−CBC treatment reduced CaCl2-extractable Cd by 14.62% and 91.79%, and reduced TCLP Cd by 9.81% and 99.8%, respectively. E−CBC was shown to effectively induce the transition of Cd in the soil to a stable state. The appl... [more]
Design and Economic Evaluation of a Hybrid Membrane Separation Process from Multiple Refinery Gases Using a Graphic Synthesis Method
Juan Aron Stron Perez, Andi Cheng, Xuehua Ruan, Xiaobin Jiang, Hanli Wang, Gaohong He, Wu Xiao
February 21, 2023 (v1)
Keywords: economic assessment, graphic synthesis method, membrane separation, process design, sensitivity analysis
Petrochemical tail gases have various components and many separation methods, thus there are many possible design schemes, making it difficult to determine the optimal scheme. In this work, a graphic synthesis method was used to design a hybrid multi-input refinery gas separation process consisting of membranes, pressure swing adsorption (PSA), shallow condensation (SC), and distillation units for the production of valuable products which include H2, C2, LPG, and C5+. Ten refinery gases with different compositions were visualized and represented with vector couples in a triangular coordinate system. Firstly, according to the characteristics of the refinery gases, the feeds located in the same region of the triangular coordinate system were merged to simplify the number of input streams, then ten original input streams were combined into two mixed streams. Secondly, the optimal separation sequence was determined by using the unit selection rules of a graphic synthesis method. Thirdly, t... [more]
Comparison in Content of Total Polyphenol, Flavonoid, and Antioxidant Capacity from Different Organs and Extruded Condition of Moringa oleifera Lam
Min-Ook Park, Choon-Il Park, Se-Jong Jin, Mi-Ri Park, Ik-Young Choi, Cheol-Ho Park, Md. Adnan
February 21, 2023 (v1)
Keywords: antioxidant, biopolymer, HME, Moringa oleifera, secondary metabolites
Recently, interest in exploring phytochemicals with health benefits has grown significantly. In this research, we aimed to develop the processing profile and functionality of Moringa oleifera Lam. Here, we implemented biopolymer-mediated extrudate formulations of M. oleifera (leaves, seed, and husk) in order to enhance the phenolic, flavonoid, and antioxidant capacity. The formulation-1 (F1) was prepared for leaves, seed, and husk using biopolymers (10% w/w), namely: whey protein isolate (10% w/w) and lecithin (5% w/w) with vitamin E (2% w/w). The formulation-2 (F2) was composed of lecithin (5% w/w) with ascorbyl palmitate (10% w/w) and vitamin E (2% w/w), processed by hot-melt extrusion (HME). It was observed that the total phenol and flavonoid contents were persistent in the lecithin-mediated F2 formulation of leaves, seed, and husk. Likewise, antioxidant capacity was significantly stayed in the F2 formulation of all organs, compared to the extrudate and control. The IC50 values reve... [more]
Techno-Economic Power Dispatching of Combined Heat and Power Plant Considering Prohibited Operating Zones and Valve Point Loading
Paramjeet Kaur, Krishna Teerth Chaturvedi, Mohan Lal Kolhe
February 21, 2023 (v1)
Keywords: cogeneration unit, combined heat and power (CHP) plant, constraint handling, techno-economic power dispatch
Co-generation units (i.e., combined heat and power plants—CHPs) are playing an important role in fulfilling the heat and power demand in the energy system. Due to the depletion of fossil fuels and rising carbon footprints in the environment, it is necessary to develop some alternatives as well as energy efficient operating strategies. By utilising the waste heat from thermal plants, cogeneration units help to decrease energy generation costs as well as reduce emitted pollutants. The combined heat and power economic dispatch (CHPED) operation strategy is becoming an important optimisation task in the energy efficient operation of a power system. The optimisation of CHPED is quite complex due to the dual dependence of heat and power in the cogeneration units. The valve point loading effect and prohibited operating zones of a thermal power unit make the objective function non-linear and non-convex. In this work, to address these issues more effectively, the viable operational area of the... [more]
Structure-Dependent Eco-Toxicity of Vegetable Tannin
Faming He, Liangqiong Peng, Wenjun Long, Xiaofeng Jiang, Wenhua Zhang
February 21, 2023 (v1)
Keywords: eco-toxicity, molecular docking, Photobacterium phosphoreum, structure, vegetable tannin
Vegetable tannin is widely applied in various industries, in agriculture, and in water treatment as a natural polyphenolic compound; however, little data has been collected concerning the relationship between structure and eco-toxicity. Here, the toxicity of six commercial tannin and three model chemicals was assessed using Photobacterium phosphoreum. Two kinds of hydrolyzed tannin displayed higher bioluminescence inhibition than four kinds of condensed tannin, and the model chemical of hydrolyzed tannin also showed greater toxicity than those of condensed tannin, indicating the structure dependent eco-toxicity of vegetable tannin. The reactive toxicity mechanism was proposed, which was illustrated by molecular simulations based on the model chemicals and luciferase.
Numerical Analysis of a Latent Heat Storage Using Plate Heat Exchanger for Absorption System Conditions
Jesús Cerezo, Fernando Lara, Rosenberg J. Romero, Gabriela Hernández-Luna, Moisés Montiel-González
February 21, 2023 (v1)
Subject: Materials
Keywords: absorption heat pump, MgCl2·6H2O, phase change material, plate heat exchanger
The use of the phase change material (PCM) as a storage medium represents an important advance to store energy for the absorption cooling systems when solar energy is not available; however, the temperature of the storage tank is a key parameter for the adequate operation of the cooling system. This paper presents a parametric analysis of a flat and a commercial plate heat exchangers with MgCl2·6H2O as the PCM at absorption cooling conditions. The plate heat exchanger (PHE) is a chevron type with an angle of 45° and a plate area of 0.04 m2. The governing equation was solved using the method of finite difference. The results showed that the corrugated plate improved the heat transfer than the flat plate; however, the flat plate obtained a higher operation time than the corrugated plate for the absorption cooling condition in the discharge process because the output temperature of the PHE was much higher than the operating conditions. Finally, the decrement of the PCM thickness and the i... [more]
Analytical Routes to Chaos and Controlling Chaos in Brushless DC Motors
Shun-Chang Chang
February 21, 2023 (v1)
Keywords: brushless DC motor, chaotic motion, Lyapunov exponent, state feedback control
This study examines the dynamics in a brushless DC motor (BLDCM) and methods used to control potentially chaotic behavior or behavior similar to chaotic processes in these systems. Bifurcation diagrams revealed complex nonlinear behaviors over a range of parameter values. In the resulting bifurcation diagram, period-doubling bifurcation, period-three bifurcation, and chaotic behavior can clearly be seen. We used Lyapunov exponents and Lyapunov dimensions to show the occurrence of chaos in a BLDCM. We then used the state feedback method to control chaos behaviors in the same BLDCM. Numerical simulations show the feasibility of the suggested means. Analysis of robustness against parametric perturbation in a BLDCM was performed from the perspective of Lyapunov stability theory and by using numerical simulations. We believe that studying the nonlinear dynamics and controlling chaos in BLDCMs will help to advance the development of high-performance electric vehicles.
Interpretation of Chemical Analyses and Cement Modules in Flysch by (Geo)Statistical Methods, Example from the Southern Croatia
Nikolina Bralić, Tomislav Malvić
February 21, 2023 (v1)
Keywords: cement, cement modules, flysch, inverse distance weighting, Kolmogorov–Smirnov, kriging, raw material, Shapiro–Wilk
This study included the testing of normal (Gaussian) distribution of input data and, consequently, spatially interpolating maps of chemical components and cement modules in the flysch. This deposit contains the raw material for cement production. The researched area is located in southern Croatia, near Split, as part of the exploited field “St. Juraj−St. Kajo”. There are six lithological units: (1) alternation of marls and sandstones with inclusions of conglomerates, (2) marl, (3) calcsiltite, (4) calcarenite, (5) marl with nummulites, (6) debrites, and (7) clayey marl. All of them are deposited in the (a) northern and (b) southern beds. Only debrites are divided into the (a) western and (b) eastern layers. Those lithological units were divided technologically based on their cement modules (lime saturation factor (LSF), silicate module (SM), and aluminate module (AM)). The average thicknesses were analysed, followed by normality tests (Kolmogorov−Smirnov (K−S) and Shapiro−Wilk (S−W)) o... [more]
A Review of Numerical Research on the Pressure Swing Adsorption Process
Runye Zhang, Yuanhui Shen, Zhongli Tang, Wenbin Li, Donghui Zhang
February 21, 2023 (v1)
Keywords: control, numerical modelling, Optimization, PSA
The pressure swing adsorption (PSA) process has been considered a promising method for gas separation and purification. However, experimental methods are time-consuming, and it is difficult to obtain the detailed changes in variables in the PSA process. This review focuses on the numerical research developed to realize the modelling, optimization and control of the cyclic PSA process. A complete one-dimensional mathematical model, including adsorption bed, auxiliary devices, boundary conditions and performance indicators, is summarized as a general modelling approach. Key simplified assumptions and special treatments for energy balance are discussed for model reliability. Numerical optimization models and control strategies are reviewed for the PSA process as well. Relevant attention is given to the combination of deep-learning technology with artificial-intelligence-based optimization algorithms and advanced control strategies. Challenges to further improvements in the adsorbent datab... [more]
Freshly Milled Quartz Particles Obtained from River Sand as an Efficient Natural Demulsifier for Crude Oil Emulsions
Kazim Nadirov, Manap Zhantasov, Zhanna Nadirova, Nurlybek Otarbaev, Gulmira Bimbetova, Rashid Nadirov
February 21, 2023 (v1)
Subject: Materials
Keywords: crude oil, demulsification, quartz particles, water-in-oil emulsion
Saline water necessarily contained in crude oil forms complex and stable water-in-oil (w/o) emulsions with oil. Due to the negative impact of this emulsion on the oil’s transportation and refining, special materials are added to help break the emulsion and separate water. Herein, a comparative study of the demulsifying ability concerning w/o emulsion of the original and freshly milled quartz (FMQ) particles isolated from river sand was carried out. The effect of quartz with a mesh size of 75 μm on reducing emulsion stability was investigated using rheological measurements, interfacial tension measurements, demulsification tests, as well as routine methods for characterizing solid and liquid materials. With the addition of 3 wt% FMQ, 97% demulsification efficiency was achieved after 100 min of settling, against 140 min for the original quartz. The role of milling quartz is to increase the ability of water to adhere and thus locally increase the pH value; this results in a reduction in t... [more]
Calibration of Hydrodynamic Models of Groundwater Flow in Aquifers Polluted by Liquid Radioactive Waste
Victor Ioannovich Malkovsky
February 21, 2023 (v1)
Keywords: aquifer, differential equations, exploratory borehole, groundwater, hydraulic conductivity, layered sequence, liquid radioactive waste, minimization problem, radioactive pollution, spatial distribution, transmissibility
Pollution of aquifers by liquid radioactive waste is especially hazardous due to high permeability of aquifer rocks. Pollution can take place as a result of deep injection disposal of liquid waste or due to its leakage from a surface reservoir. The ecological hazard depends on distribution of aquifer permeability, which can be highly heterogeneous. The only source of data for determination of such distribution is measurements in exploratory boreholes at the polluted site. A technique is proposed for determination of spatial distribution of aquifer transmissibility on the basis of hydrological measurements in a limited number of boreholes. The problem is reduced to a minimization problem which was solved numerically.
Study of Gas-to-Liquid Heat Pipe Heat Exchanger
Pratik Prakash Gupta, Sundararaj Senthilkumar, Shung-Wen Kang
February 21, 2023 (v1)
Keywords: effectiveness, gas-to-liquid, heat exchanger, heat pipe, numerical analysis, waste heat recovery
This study is focused on the study and development of a gas-to-liquid heat pipe heat exchanger (HPHE) based on numerical and experimental analysis. Stainless steel heat pipes were installed inside the heat exchanger in the form of three equilateral triangles, staggered into a hexagonal configuration to simulate the waste heat recovery from hot exhaust gas to a water flow. The first main aim of this study was focused on 3D design and numerical analysis, which were used to create and calculate the effect of similar input conditions on the overall system. The system was tested for the overall heat transfer by measuring the temperature change in both fluids. The heat transfer and overall average temperature were used to calculate the effectiveness of the system. In the second part of this study, a test of the waste heat recovery was undertaken with this setup, using water as the cooling fluid. The study was conducted with different input velocities and temperatures of waste hot air, contro... [more]
Digital Twins for scFv Production in Escherichia coli
Heribert Helgers, Alina Hengelbrock, Axel Schmidt, Florian Lukas Vetter, Alex Juckers, Jochen Strube
February 21, 2023 (v1)
Keywords: advanced process control (APC), digital twin (DT), Escherichia coli (E. coli), process analytical technology (PAT), quality-by-design (QbD), real-time-release testing (RTRT), single-chain fragment variable (scFv)
Quality-by-Design (QbD) is demanded by regulatory authorities in biopharmaceutical production. Within the QbD frame advanced process control (APC), facilitated through process analytical technology (PAT) and digital twins (DT), plays an increasingly important role as it can help to assure to stay within the predefined proven acceptable range (PAR).This ensures high product quality, minimizes failure and is an important step towards a real-time-release testing (RTRT) that could help to accelerate time-to-market of drug substances, which is becoming even more important in light of dynamical pandemic situations. The approach is exemplified on scFv manufacturing in Escherichia coli. Simulation results from digital twins are compared to experimental data and found to be accurate and precise. Harvest is achieved by tangential flow filtration followed by product release through high pressure homogenization and subsequent clarification by tangential flow filtration. Digital twins of the membra... [more]
A Synthetic Chart for Internal Stability Assessment of Soils Based on Soil PSD Curves
Yongbiao Lai, Songsong Bai, Jian Hou, Zongqing Zhou, Qiangling Wu, Xiaobo Lv, Liming Yang, Weixun Cao, Zhengtao Ren
February 21, 2023 (v1)
Keywords: granular soil, internal stability, mathematical modelling, PSD curves, semi-empirical criterion
Awareness of granulated soils’ internal instability is an important parameter when designing granulated filters, and the ability of a granulated soil’s internal stability can be verified using the soil PSD (Particle Size Distribution) curves’ secant slopes. The current work presents a new method to calculate the soil PSD curves’ secant slopes automatically, and a synthetic diagram is presented for the potential examination of the granulated soils’ internal stability. To verify the feasibility and accuracy of this synthetic diagram, 80 specimens of soil were investigated in this work and categorized into two groups: 50 sand−gravel soils and 30 (clay)−silt−sand−gravel soils. The obtained conclusions indicate that the internal stability and instability potentials of sand−gravel soils can be distinguished successfully with a synthetic chart and the Kenney and Lau criterion but cannot be assessed with the Kezdi and Sherard criteria. None of the criteria studied here can be used for the inte... [more]
Hydrodynamics of an Elliptical Squirmer
Chen Liu, Peijie Zhang, Jianzhong Lin, Zhenyu Ouyang
February 21, 2023 (v1)
Keywords: elliptical squirmer, hydrodynamic efficiency, IB-LBM, power expenditure, velocity
In this paper the propulsion of elliptical objects (called squirmers) by imposed tangential velocity along the surface is studied. For a symmetric velocity distribution (a neutral squirmer), pushers (increased tangential velocity on the downstream side of the ellipse) and pullers (increased tangential velocity on the upstream side of the ellipse), the hydrodynamic characteristics, are simulated numerically using the immersed boundary-lattice Boltzmann method. The accuracy of the numerical scheme and code are validated. The effects of Reynolds number (Re) and squirmer aspect ratio (AR) on the velocity u*, power expenditure P* and hydrodynamic efficiency η of the squirmer are explored. The results show that the change of u* along radial direction r* shows the relation of u*~r*−2 for the neutral squirmer, and u*~r*−1 for the pusher and puller. With the increase of Re, u* of the pusher increases monotonically, but u* of the puller decreases from Re = 0.01 to 0.3, and then increases from Re... [more]
Effect of Counterbody on Friction and Wear Properties of Copper-MgP-Graphite Composites Prepared by Powder Metallurgy
Ruoxuan Li, Seiji Yamashita, Katsumi Yoshida, Hideki Kita
February 21, 2023 (v1)
Subject: Materials
Keywords: copper-matrix composite, counterbody, friction, graphite, Magnesium Phosphate, sliding wear, wear
The purpose of this study was to investigate the influence of different counterbodies against Cu/magnesium phosphate treated graphite (Cu-MgPG) composite materials to find the best material combination in terms of friction coefficient and specific wear amount. A Cu matrix composite reinforced with 10 vol% magnesium phosphate treated graphite and pure Cu powder were prepared by powder metallurgy techniques under the same consolidation processing condition. The friction and wear properties of the composites were investigated at 10 N using a pin-on-disc tribometer on Al2O3, SiC and SUJ2 bearing steel counterbodies. The Cu-MgPG/Al2O3 pair showed the lowest friction coefficient, but the specific wear rate tended to increase slightly when compared with Cu/Al2O3 pair. On the other hands, the Cu-MgPG/SUJ2 pair showed about the same specific wear rate as the Cu/SUJ2 pair, but the friction coefficient was significantly reduced. These phenomena are thought to be due to the fact that the added gra... [more]
The Inhibitory Activity of Citral against Malassezia furfur
Yi-Tsz Liu, Meng-Hwan Lee, Yin-Shen Lin, Wen-Lin Lai
February 21, 2023 (v1)
Subject: Biosystems
Keywords: citral, human keratinocyte, immunomodulation, Malassezia furfur, yeast apoptosis
The lipophilic yeast Malassezia furfur, is a member of the cutaneous commensal microbiota and is associated with several chronic diseases such as dandruff, pityriasis versicolor, folliculitis, and seborrheic dermatitis, that are often difficult to treat with current therapies. The development of alternatively effective antifungal therapies is therefore of paramount importance. In this study, we investigated the treatment effect of citral on M. furfur. The minimal inhibitory concentration of citral for M. furfur was 200 μg/mL, and the minimal fungicidal concentration was 300 μg/mL. Citral significantly increased the proportion of yeast cells to mycelial forms 2.6-fold. Phosphatidylserine externalization, DNA fragmentation, and metacaspase activation supported a citral-induced apoptosis in M. furfur. Moreover, citral at sub-minimum inhibitory concentrations reduced the invasion of M. furfur in HaCaT keratinocytes. Finally, we demonstrated that citral inhibited IL-6 and TLR-2 expression a... [more]
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