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Showing records 151 to 175 of 4208. [First] Page: 3 4 5 6 7 8 9 10 11 Last
A Review on Impacting Parameters for Photocatalytic Degradation of Organic Effluents by Ferrites and Their Nanocomposites
Gurpinder Singh, Manpreet Kaur Ubhi, Kiran Jeet, Chetan Singla, Manpreet Kaur
July 7, 2023 (v1)
Subject: Materials
Keywords: ferrites, mechanism, nanocomposites, parameters, photocatalyst, photodegradation
Traditional wastewater treatment methods, such as reverse osmosis, adsorption, desalination, and others, are outweighed by the photocatalytic degradation of organic pollutants. Ferrites are prominent photocatalysts due to their tunable band gaps, surface areas, and magnetic properties, which render photodegradation economical. Ferrites and their nanocomposites have been reported as promising visible light active photocatalysts. The photocatalytic system is heavily reliant on a number of factors that influence the photodegradation of organic effluents. This review demonstrates various parameters such as substrate concentration, pH of solution, photocatalyst quantity, photocatalyst surface area, metal and non-metal ion doping, light intensity, irradiation time, quenchers, etc. affecting the photocatalytic degradation of organic effluents by ferrite nanoparticles and their nanocomposites in detail. The photodegradation efficiency of the ferrite nanoparticles alters with the change in the... [more]
Mechanical Properties of Full-Grouted Prestressed Anchor Bolts under Typical Bed-Separation Conditions
Zhen Zhu, Fulu Shang, Yubin Gao, Zelin Lu, Peng Zhang, Mingqing Du, Xiaoming Guan, Xuchun Wang
July 7, 2023 (v1)
Subject: Materials
Keywords: bed separation, full-grouted anchor bolts, mechanical property, prestressing force
For tunnel-support engineering, the bed separation of surrounding rock has a great influence on the support performance of bolts. In order to reveal the mechanical properties of the full-grouted prestressed bolt under the influence of bed separation, three typical working conditions of single-separation, multi-separation and different separation positions were set up, and theoretical models and numerical models were established. Furthermore, the characteristics of bolt axial force and anchorage−interface shear stress were analyzed by numerical method, and the sensitivity based on an orthogonal test was studied by means of range analysis and variance analysis. The results showed that: (1) under the single-separation condition, the separation value has a significant effect on the mechanical properties of the bolt, and with the increase in the separation value, the sliding failure unit of the bolt increases; (2) for multi-separation conditions, if the total separation value is the same, t... [more]
Evaluation of a Resorcinarene-Based Sorbent as a Solid-Phase Extraction Material for the Enrichment of L-Carnitine from Aqueous Solutions
Gabriel Ramirez, Nicolas Alejandro Cadavid-Montoya, Mauricio Maldonado
July 7, 2023 (v1)
Subject: Materials
Keywords: calix[4]resorcinarenes, carnitine, monolith, pre-concentration
We present five new sorbents for the evaluation of the pre-concentration of L-carnitine. The sorbents were obtained from copolymerization between butylmethacrylate (BuMA) and ethylene dimethacrylate (EDMA), which were physically modified on their surface by each one of the five synthetized resorcinarenes of variable chain length studied, with long-chain resorcinarenes exhibiting better fixation on the copolymer. The characterization of the synthesized resorcinarenes was done using FTIR-ATR, 1H NMR, 13C NMR, and mass spectrometry, while characterization of the sorbents was done using FTIR-ATR and scanning electron micrography (SEM). The molecular interaction between L-carnitine and the synthesized resorcinarenes was studied in DMSO via 1H-NMR spectroscopy and, in the gas phase, via electrospray ionization-mass spectrometry (ESI-MS). The results showed that the short-chain resorcinarenes underwent a stable interaction with the neurotransmitter. Once the sorption of resorcinarenes on the... [more]
Transport Properties of Carbohydrates: Towards the Minimization Toxicological Risks of Cobalt and Chromium Ions
Ana C. V. Trindade, Sónia I. G. Fangaia, Pedro M. G. Nicolau, Ana Messias, Ana C. F. Ribeiro, Daniela S. A. Silva, Artur J. M. Valente, M. Melia Rodrigo, Miguel A. Esteso
July 7, 2023 (v1)
Subject: Materials
Keywords: chromium, Co-Cr alloys, cobalt, cyclodextrins, diffusion coefficient, hyaluronic acid, Taylor dispersion, transport properties
The influence of oligosaccharides (α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin), and a polysaccharide, sodium hyaluronate (NaHy), on the diffusion of aqueous solutions of cobalt and chromium chlorides has been investigated. Cobalt and chromium are constituents of metal alloys for biomedical use, including dental prostheses. Thus, the release of these ions in the human body can lead to harmful biological effects. The interaction of metal ions with saccharides might have information on the role of mouthwashes in preventing these effects. This interaction has been assessed by measuring multicomponent intermolecular diffusion coefficients at 298.15 K. It has been found that β-cyclodextrin has the highest interaction towards cobalt and chromium ions. This work will contribute to unveiling the mechanisms responsible for transport by diffusion in aqueous solutions, and, therefore, mitigating the potential toxicity inherent to those metal ions.
Research on Pore-Fracture Characteristics and Adsorption Performance of Main Coal Seams in Lvjiatuo Coal Mine
Wu Li, Jin Li, Changqing Hu, Qianlong Xiao
July 7, 2023 (v1)
Subject: Materials
Keywords: Coal, coal reservoir, CT, pore
Gas prevention and control have always been the focus of coal mine safety. The pore structure characteristics and gas adsorption characteristics of coal seams are the key factors affecting gas adsorption and diffusion in coal seams. Lvjiatuo Mine has the characteristics of a high gas content when it enters deep mining. In order to clarify the influence of the pore-fracture structure characteristics of main coal seams in the research area on coal seam gas adsorption and diffusion, and to study the differences in gas adsorption and diffusion ability in different coal seams, low-temperature nitrogen adsorption (LT-N2GA), high-pressure mercury intrusion (MIP) and computerized tomography (μ-CT) were used as characterization methods, and methane isothermal adsorption experiments were carried out to systematically study the pore structure characteristics of five groups of coal samples, and the pore-fracture structure characteristics and gas adsorption characteristics of each main coal seam we... [more]
Optimizing Pressure Prediction Models for Pneumatic Conveying of Biomass: A Comprehensive Approach to Minimize Trial Tests and Enhance Accuracy
Hossein Rajabnia, Ognjen Orozovic, Kenneth Charles Williams, Aleksej Lavrinec, Dusan Ilic, Mark Glynne Jones, George Klinzing
July 7, 2023 (v1)
Subject: Materials
Keywords: Biomass, dense phase, plug flow, pneumatic conveying
This study investigates pneumatic conveying of four different biomass materials, namely cottonseeds, wood pellets, wood chips, and wheat straw. The performance of a previously proposed model for predicting pressure drop is evaluated using biomass materials. Results indicate that the model can predict pressure with an error range of 30 percent. To minimize the number of trial tests required, an optimization algorithm is proposed. The findings show that with a combination of three trial tests, there is a 60 percent probability of selecting the right subset for accurately predicting pressure drop for the entire range of tests. Further investigation of different training subsets suggests that increasing the number of tests from 3 to 7 can improve the probability from 60% to 90%. Moreover, thorough analysis of all three-element subsets in the entire series of tests reveals that when considering air mass flow rate as the input, having air mass flow rates that are not only closer in value but... [more]
Investigating the Relationship between the Time Constant Ratio and Plug-Flow Behaviour in the Pneumatic Conveyance of Biomass Material
Hossein Rajabnia, Ognjen Orozovic, Kenneth Williams, Aleksej Lavrinec, Dusan Ilic, Mark Jones, George Klinzing
July 7, 2023 (v1)
Subject: Materials
Keywords: aeration, Biomass, deaeration, dense phase, fluidisation, plug flow, pneumatic conveying, time constant
This study introduces a novel methodology to evaluate the behaviour of biomass material by examining the ratio of aeration and deaeration time constants. To this end, a series of tests were conducted on four different materials, namely, cottonseed, wood chips, wood pellets, and wheat straw, in order to investigate their aeration and deaeration behaviours. The study derives the aeration and deaeration pressure drop equations, and discusses the corresponding time constant expression. Subsequently, the four materials were conveyed in 12 m long batch-fed and continuous pneumatic conveying pipelines to examine their behaviour in longer pipelines. The results indicate that the aeration and deaeration time constants increased with an increase in air superficial velocity. However, the ratio of the aeration and deaeration time constants was identified as a unique number, where a value close to 1 indicates a higher likelihood of plug flow. On the basis of the results, cottonseed, with the lowest... [more]
Novel Stimulants of Medicinal Basidiomycetes Growth Based on Nanoparticles of N-monosubstituted Amino Acid Derivatives of Fullerene C60
Mikhail Voronkov, Olga Tsivileva, Vladimir Volkov, Valentina Romanova, Vyacheslav Misin
July 7, 2023 (v1)
Subject: Materials
Keywords: amino acid derivatives, fullerene C60, Laetiporus sulphureus, mushrooms, oxidative stress, submerged culture
The influence of nanoparticles of hydrated C60 fullerene and its N-monoamino acid derivatives on the oxidative metabolism and growth of the mycelial biomass of basidiomycetes during their submerged cultivation was studied. It was found that the supplementation of culture media with nanoparticles of the studied compounds at their final concentration range of 10−7 to 10−11 M significantly increased the resulting biomass, while the severity of the effect in this concentration range changed slightly. That prompted the use of nanomolar concentrations of compounds as reasonable. The most pronounced stimulating effect (an increase in biomass of about 240% with respect to control) was observed when culturing Laetiporus sulphureus, the intrinsically high level of oxidative metabolism of which was significantly lowered by the presence of the studied additives. It was shown that the growth-enhancing action of nanoparticles of fullerene C60 and its derivatives could not be attributed to photochemi... [more]
A Comprehensive Study on the Acidic Compounds in Gas and Particle Phases of Mainstream Cigarette Smoke
Xinbo Lu, Hongfei Zhang, Yifeng Cao, Yongqiang Pang, Guojun Zhou, Hua Huang, Jing Li, Jian Jiang, Qiwei Yang
July 7, 2023 (v1)
Subject: Materials
Keywords: acidic compounds, acidic gas phase, mainstream cigarette smoke, multivariate analysis, particle phase
Acidic compounds constitute a group of chemicals present in mainstream cigarette smoke, among which organic acids contribute to flavoring. In order to obtain a comprehensive understanding of the constituents of acidic compounds in both the particulate and gaseous phases of the mainstream smoke of commercial cigarettes, and to delineate the difference between two types of cigarettes, the yields of acidic constituents from nine cigarettes of two commercial brands (L- and M-types) were collected and analyzed in detail by gas chromatography−mass spectrometry (GC-MS). The results identified and quantitatively analyzed 46 compounds, grouped according to the substituent groups. Compositional differences between the two cigarette types were evaluated with statistical approaches. Comparison between individual, grouped, and total acid contents, between the particulate and the gaseous phases, and between the commercial L- and M-type tobaccos were conducted and characterized by the p values obtain... [more]
Highly Sensitive Ethylene Sensors Based on Ultrafine Pd Nanoparticles-Decorated Porous ZnO Nanosheets and Their Application in Fruit Ripeness Detection
Zhen Jin, De-Cai Wang, Wen-Jie Xie, Yi Ding, Jie Li
July 7, 2023 (v1)
Subject: Materials
Keywords: ethylene sensors, fruit ripeness, porous ZnO nanosheets, ultrafine Pd nanoparticles
Ethylene is the most common ripening phytohormone in fruits, and excess ethylene can overripen the fruit. However, the in-field detection of ethylene is still limited. In this work, ultrafine Pd nanoparticles-decorated porous ZnO nanosheets (UPNP ZnO nanosheets) were conveniently synthesized through a facile solvent reduction method. The UPNP ZnO nanosheets were characterized using scanning electron microscopy, transmission electron microscopy, energy dispersive spectrum, X-ray diffraction and X-ray photoelectron spectroscopy. The ZnO nanosheets were uniformly coated with Pd nanoparticles. The size of the Pd nanoparticle was very small, with a diameter of approximately 2 nm. Due to the unique structure of the porous ZnO nanosheets and the excellent catalytic properties of the ultrafine Pd nanoparticles, the as-prepared samples showed very high sensing performance in ethylene detection. The lowest detection concentration was 10 ppb, which is the lowest detection limit to our knowledge.... [more]
Extraction and Characterization of Silica from Empty Palm Fruit Bunch (EPFB) Ash
Ebitei Sintei Nelson, Sunny Iyuke, Michael Olawale Daramola, Akindele Okewale
July 7, 2023 (v1)
Subject: Materials
Keywords: amorphous phase, biomass waste, calcination, pyrolyzed ash, silica
Recently, there has been so much interest in using biomass waste for bio-based products. Nigeria is one of the countries with an extensive availability of palm biomass. During palm oil production, an empty palm fruit bunch (biomass) is formed, and a lot of ash is generated. This study aimed to extract and characterize silica from empty palm fruit bunch (EPFB) ash using the thermochemical method. The results show that EPFB ash contains a large amount of biogenic silica in its amorphous form. It could be extracted for further use via calcination at different temperatures and compared effectively to other biomass materials, such as rice husk ash, sugarcane bagasse, and cassava periderm. The extracted silica was characterized using XRF, XRD, TGA, SEM, and FTIR, revealing the highest silica concentration of 49.94% obtained at a temperature of 800 °C. The XRF analysis showed 99.44 wt.% pure silica, while the XRD spectrum showed that the silica in EPFB is inherently amorphous. As is evident f... [more]
The Development and Deployment of Degradable Temporary Plugging Material for Ultra-Deepwater Wells
Zhiqin Liu, Jiafang Xu, Wei Peng, Xiaodong Yu, Jie Chen
July 7, 2023 (v1)
Subject: Materials
Keywords: deepwater, dynamic covalent crosslinking, loss-circulation material, reservoir protection, thixotropy degradation
The fractured granite reservoir is well developed in Yongle block, which leads to severe drilling fluid loss-circulation. To solve the technical problem of both plugging and reservoir protection, on the basis of comprehensive literature research and laboratory tests at home and abroad, a polymer with an appropriate molecular weight, an organic crosslinking agent and other auxiliary materials were screened. In addition, a kind of high-temperature resistant loss-circulation plugging gel, which could be formed by timing and self-degradation, was developed. The high-strength gel loss-circulation system can be established by the development of a dynamic covalent borate ester bond crosslinking agent, which can crosslink with polyvinyl alcohol and xanthan gum. This system is of formidable strength and can be used for loss-circulation control in a fractured formation. The dynamic covalent borate ester bond tends to break due to the peroxide glue breaker under low pH levels, which can accelerat... [more]
Fabrication of Micro-Dimple Arrays by EMM and RUREMM on Cylindrical Surface
Wenjun Tong, Tao Lv, Jianlei Wu, Wei Zhang, Xuefeng Xu, Minghuan Wang
July 7, 2023 (v1)
Subject: Materials
Keywords: electrochemical micromachining, localization, micro-dimple arrays, radial ultrasonic rolling electrochemical micromachining (RUREMM), rolling velocity, ultrasonic amplitude
To achieve high precision, stability, and good surface quality when producing micro-dimple arrays on cylindrical surfaces, we propose a new processing method known as radial ultrasonic rolling electrochemical micromachining (RUREMM) in this study. This method is based on the electrochemical micromachining (EMM) and ultrasonic machining principle. The relevant simulation model was created, and ANSYS researched the flow field characteristics of the electrolyte between the array electrodes and the workpiece. Micro-dimple arrays were created on a SS304 cylindrical surface with the consideration of the effects of the machining parameters, including ultrasonic amplitude and applied pulse voltage. Compared with the EMM, the average width of the micro-dimples is reduced by 24.5%, the aspect ratio of the dimple is increased by 108.0%, and the surface roughness of micro-dimples is decreased by 59.7%. In addition, the localization and the surface quality of micro-dimples by RUREMM can be improved... [more]
Study on the Influence of the Strain-Softening of the Surrounding Rock with Buried Depth on Gas Extraction Boreholes
Junqi Cui, Yun Zheng, Xiangxiang Yan, Yunbing Hou, Shengrong Xie, Dongdong Chen, Yuxin Ren
July 7, 2023 (v1)
Subject: Materials
Keywords: buried depth, gas extraction, gas pressure, Mohr–Coulomb, permeability, strain-softening
The buried depth of coal seams in China gradually increases as shallow resources decrease. The purpose of this article is to reveal the effect of buried depth on gas extraction boreholes. Firstly, we analyzed the shortcomings of the Mohr−Coulomb (M-C) constitutive model for simulating excavation problems and introduced the strain-softening (S-S) model and its advantages. Subsequently, we constructed the gas extraction models with different buried depths based on the S-S model and combined them with the evolution equations for permeability and the equations for gas migration. Then, we studied the difference between the M-C and S-S models using numerical simulations. We found that the influence of the S-S phenomenon in the surrounding rock of boreholes is more significant as the buried depth increases—that is, the strain-softening has a significant buried depth effect. When the buried depths were 300, 500, and 700 m, the maximum ratios of permeability to the initial permeability obtained... [more]
Two Potential Ways of Vanadium Extraction from Thin Film Steelmaking Slags
Tetiana Shyrokykh, Lukas Neubert, Olena Volkova, Seetharaman Sridhar
July 7, 2023 (v1)
Subject: Materials
Keywords: evaporation, recycling, Single Hot Thermocouple Technique, spinel formation, vanadium pentoxide
During the steelmaking process, a great amount of slag is generated as a by-product. Vanadium-bearing steelmaking slags are classified as hazardous and require special handling and storage due to the toxicity of vanadium pentoxides. At the same time, such slags are valuable sources for the recovery of vanadium. The present work reviews the investigations on vanadium recovery from CaO-SiO2-FeO-V2O5 thin film slags under the neutral and oxidizing conditions in the temperature range 1653 K to 1693 K (1380 °C to 1420 °C) using Single Hot Thermocouple Technique (SHTT). The slag samples were analyzed by SEM/EDX. The results indicated that vanadium pentoxide evaporation can be up to 17.73% under an oxidizing atmosphere, while spinel formation under an argon atmosphere was detected in the conditions of thin film slags.
Effective Removal of Ammonium from Aqueous Solution by Ball-Milled Biochar Modified with NaOH
Hefeng Yang, Xiangming Li, Yuting Wang, Junxia Wang, Lihong Yang, Zhiqiang Ma, Jipeng Luo, Xiaoqiang Cui, Beibei Yan, Guanyi Chen
July 4, 2023 (v1)
Subject: Materials
Keywords: ammonium, ball milling, biochar, modification, sorption
The objective of this study was to investigate the feasibility of using modified biochars to enhance removal of ammonium from aqueous solution. The pristine, NaOH-modified, ball-milled, and NaOH-modified ball-milled biochars were prepared from wheat straw at 500 °C. The surface morphology and characteristics of biochar were obviously changed after modification. The NaOH-modification elevated the pH value and ash content of biochar, and the ball-milling treatment promoted the formation of oxygen-containing functional groups. The specific surface area of biochar (20.9 m2/g) increased to 51.4 m2/g and 145.6 m2/g after NaOH-modification and ball-milling treatment, respectively. The modified biochars showed considerable ammonium sorption capacity in a wide pH range (3−7), and the optimal pH of ammonium sorption was around 6. Both NaOH-modification and ball-milling treatment improved ammonium sorption on the biochars. Ammonium sorption of the biochars could be well fitted by the Langmuir and... [more]
Characteristic Analysis of Finite Dissipation Zone in Directional Material Flow
Hong Ren, Wenjun Meng, Xiaoxia Sun, Zhangda Zhao, Xiaoxia Zhao
July 4, 2023 (v1)
Subject: Materials
Keywords: DEM, directional material flow, finite dissipation zone, material movement
Materials compress each other in a directional material flow, causing energy and momentum to overflow. Materials moving at a low velocity outside the boundary of a rigid moving component form a finite dissipation zone. A discrete element model is established to explore its characteristics. First, the mass of material driven by the disk increases linearly with an increase in the translation distance, and the mass of material moving at a low velocity increases significantly. Second, the movement state of materials depends on its distance from the disk. The material velocity at the boundary of the finite dissipation zone is verified to be 1 mm/s by analyzing the material velocity and contact force. When the operating parameters are different, the boundary curves of the finite dissipation zone are similar but the numerical values are different. Third, the maximum edge extends 0.7−3.0 mm beyond the boundary, and this value is linearly related to the translation velocity with little impact f... [more]
Indium Recycling from Waste Liquid Crystal Displays: Is It Possible?
Aleksandra Anić Vučinić, Snježana Šimunić, Lucija Radetić, Ivana Presečki
July 4, 2023 (v1)
Subject: Materials
Keywords: indium recovery, liquid crystal displays (LCDs), liquid crystals, recycling, waste electric and electronic equipment (WEEE)
The utilization of valuable properties of waste and their reuse as raw materials is an imperative of the circular economy. Waste electrical and electronic equipment (WEEE) is a significant source of valuable raw materials, certain metals, and rare earth elements that are the basis for highly sophisticated IT equipment production. It is estimated that the production of WEEE in Europe in 2019 was 16.20 kg/inhabitant, while quantities continue to grow at a rate of 3−4% per year. Waste liquid crystal displays used in televisions, laptops, desktops, and other devices represent a significant share of WEEE and contain 0.12−0.14% of liquid crystals whose main ingredient is indium—tin oxide. In order to investigate and determine the methods and conditions of indium recycling from waste LCDs, laboratory research was conducted. The influence of temperature, particle size, and retention time in different media with and without ultrasound treatment was monitored to provide the efficiency of indium... [more]
Chitosan Glutaraldegyde Cryogels for Wastewater Treatment and Extraction of Silver Nanoparticles
Dmitriy Berillo, Aknazar Arysbek
July 4, 2023 (v1)
Subject: Materials
Keywords: chitosan, cryogels, Freundlich adsorption isotherm, Langmuir adsorption isotherm, nanoparticles, Wastewater
The discharge of nanoparticles into the environment, such as through industrial plants and municipal wastewater treatment plants, can pose a hazard to aquatic life. This study demonstrates the effective removal of silver nanoparticles (AgNPs) using a chitosan-based cryogel, which has potential applications in agriculture, as well as in water treatment or in industrial plants that discharge into environmentally sensitive water bodies. The adsorbent is economically viable, has high affinity toward metal nanoparticles, is biodegradable and biocompatible, and displays a good removal of nanoparticles. AgNP adsorption was monitored using UV/Vis spectroscopy and TEM analysis. SEM, nitrogen adsorption, TGA, and FTIR analysis were used for cryogel characterization. The BET model of nitrogen adsorption revealed a specific surface area of 7.7 m2/g for chitosan−glutaraldehyde (CHI−GA) cryogels. The elasticity modulus of the CHI−GA cryogel was estimated as 543 ± 54 kPa. The AgNPs were characterized... [more]
Interplay between Thermally Induced Aragonite−Calcite Transformation and Multistep Dehydration in a Seawater Spiral Shell (Euplica scripta)
Taiga Tone, Nobuyoshi Koga
July 4, 2023 (v1)
Subject: Materials
Keywords: aragonite–calcite transformation, biomineralized aragonite, kinetics, mechanistic relationship, multistep thermal dehydration
While heating a seawater spiral shell (Euplica scripta), thermally induced aragonite−calcite (A−C) transformation occurred within the temperature region of multistep thermal dehydration. Here, the kinetic interplay between the A−C transformation and thermal dehydration was studied as a possible cause of the reduction in the A−C transformation temperatures. The kinetics of the A−C transformation was systematically investigated under isothermal conditions by powder X-ray diffractometry and under linear nonisothermal conditions by Fourier transform infrared spectroscopy. The thermal dehydration was characterized as a partially overlapping, three-step process by thermogravimetry−differential thermal analysis coupled with mass spectroscopy for the evolved gases. The A−C transformation occurred in the temperature range of the final part of the second dehydration step and the initial part of the third dehydration step. The kinetics of A−C transformation and thermal dehydration were characteri... [more]
Studying the Antioxidant and the Antimicrobial Activities of Leaf Successive Extracts Compared to the Green-Chemically Synthesized Silver Nanoparticles and the Crude Aqueous Extract from Azadirachta indica
Mostafa Ahmed, Diaa Attia Marrez, Nadia Mohamed Abdelmoeen, Ebtesam Abdelmoneem Mahmoud, Mohamed Abdel-Shakur Ali, Kincső Decsi, Zoltán Tóth
July 4, 2023 (v1)
Subject: Materials
Keywords: Ag-NPs, antibacterial, antifungal, antioxidant, Azadirachta indica, polyphenols
has several medicinal uses, especially its leaves. Over 4000 years ago, Ayurvedic medicine used it for its therapeutic benefits. This study examined the biological activity of Neem crude extracts and green-chemically produced Ag-NPs. TPCs and TFCs were measured for polyphenolic burden in consecutive extracts. DPPH, ABTS, and FRAP experiments measured antioxidant and antimicrobial activity against seven strains of food-borne pathogenic bacteria and eight mycotoxigenic fungi. At 1000 μg/mL, ethanolic and aqueous extracts of Neem leaves had 80.10% and 69.41% in DPPH and 71.42% and 74.61% in ABTS assays for the antioxidant activity, compared to 93.58% for BHT. At 800 μg/mL, both extracts showed antioxidant activity with 57.52 and 57.87 μM in the FRAP assay, compared to 139.97 μM for Ascorbic acid. Both extracts demonstrated antimicrobial activity with 0.02 to 0.35 mg/mL as antibacterials, 0.03 to 2.17 mg/mL as antifungals, and 0.04 to 0.42 mg/mL as antibacterials. Compared to Neem crude ex... [more]
Research of an Abandoned Tailings Deposit in the Iberian Pyritic Belt: Characterization and Gross Reserves Estimation
Diego Davoise, Ana Méndez
July 4, 2023 (v1)
Subject: Materials
Keywords: abandoned tailings deposit, critical raw materials, secondary raw materials
Global situations such as economic recovery after a pandemic, geopolitical instability, and future digital and energy transition are some of the drivers for the European Union (EU) to explore new and existing sources of raw materials. The Iberian Pyrite Belt in the southwest of the Iberian Peninsula (Spain and Portugal) hosts a great number of tailing deposits from centuries of mining operations. A unique tailings deposit has been studied and characterized. The similarities with other tailing deposits deeply studied suggested the presence of critical raw materials. Furthermore, a very gross reserves estimation was made. The characterization and reserves estimations were compared with the bibliography from mining companies who operated in the area decades ago and from the bibliography available at Fundación Riotinto. The presence of critical raw materials was confirmed, some of them in high concentrations. Moreover, a singular difference was found compared with other similar tailings st... [more]
Soil Destabilization Induced by Water Wetting Treatments Simulating Rain Infiltration Processes, Studied via Rheology and Granulometry
Claudia Carotenuto, Mario Minale
July 4, 2023 (v1)
Subject: Materials
Keywords: dissoluble organic carbon, landslide, mudflow, natural hazard, particle size distribution, slurry, soil organic carbon, vane geometry
A soil depleted of its organic carbon content is typically destabilized, i.e., its capacity to maintain its microstructure intact under various stress conditions weakens, and consequently, landslides and mudflows can be triggered and propagated more easily. In a previous work, we showed with a rheological analysis that the removal of the sole water-soluble organic carbon “destabilized” the slurry very similarly to what occurs with the removal of the vast majority of soil organic carbon. In principle, the water-soluble organic carbon can be dissolved by rainfall, during which water can infiltrate the soil, eventually leaving it either by percolation or evaporation. These two processes are mimicked here with two different soil water wetting procedures. The stability of the treated (wetted) soils is studied with rheological and granulometric experiments. The former run on concentrated suspensions, while the latter run on very diluted ones. Despite this, the results agreed very well, indic... [more]
Catalytic Degradation of Tetracycline Hydrochloride by Coupled UV−Peroxydisulfate System: Efficiency, Stability and Mechanism
Panfeng Ma, Yu Shi, Jingsen Zhang, Weijia Zhang, Yong Cao, Bingtao Liu
July 4, 2023 (v1)
Subject: Materials
Keywords: advanced oxidation, CuFe2O4, peroxydisulfate, photocatalytic, tetracycline
Magnetic CuFe2O4 powder obtained by sol−gel method and coupled photocatalysis was used to activate peroxydisulfate for tetracycline (TC) removal. A scanning electron microscope, X−ray diffraction Raman spectroscopy and FT−TR were used to characterize the catalysts. The degradation efficiency and stability of TC were highest under neutral conditions. The TC degradation rate reached 91.1% within 90 min. The removal rate of total organic carbon reaches 39.6% under optimal conditions. The unique electron transfer property of CuFe2O4 was utilized to achieve the synergistic effect of photocatalysis and persulfate oxidation. The main oxidizing substances involved in the decomposition were sulfate radicals and hydroxyl radicals, and the removal rate of over 84% could be maintained after five cycles of experiments.
Dynamic Evolution and Quantitative Characterization of Fractures in Coal at the Eastern Edge of Ordos Basin under Axial Loading
Yinghao Zhu, Yineng Tan, Songhang Zhang, Mengdie Wang, Bingyi Wang
July 4, 2023 (v1)
Subject: Materials
Keywords: fracture evolution, quantitative characterization, the eastern edge of Ordos, uniaxial compression, μ-CT
Understanding the evolution of pore-fracture networks in coal during loading is of paramount importance for coalbed methane exploration. To shed light on these dynamic changes, this study undertook uniaxial compression experiments on coal samples collected from the eastern edge of the Ordos Basin, complemented by μ-CT scanning to obtain a 3D visualization of the crack network model. The compression process was divided into three stages, namely, micro-crack compaction, linear elasticity, and peak failure. An increase in stress resulted in greater concentration and unevenness in fractal dimensions, illustrating the propagation of initial cleats and micro-cracks in the dominant crack direction and the ensuing process of crack merging. These results provide valuable insights into the internal structure and behavior of coal under stress, informing more efficient strategies for coalbed methane extraction.
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