Fine Particle Size Research Articles

Adverse Effects and Underlying Mechanisms of Soil Microplastics on Crops and Its Preventive Strategies

Microplastics （MPs）, as a type of emerging environmental pollutant with a particle size < 5 mm, have been frequently detected in environmental matrices. MPs pollution in soils has been attracting the scientific community due to the increasing contaminant areas and continuous accumulation, leading to a high risk to crop production. In addition, recent studies have observed that long-term exposure to MPs could seriously harm the soil ecosystem because of their fine particle size and persistence in soils. Given that, in this review, we summarized the pollution status of MPs in soils, the adverse effects and underlying mechanisms of soil microplastics on crops, and their preventive strategies. The hazardous substances that may be released by MPs and the toxic mechanisms of MPs or MPs/absorbed contaminants were reviewed. The results suggested that the main adverse effects of soil MPs on crops were mechanical damage, oxidative stress reactions, and genotoxicity to plants, eventually leading to disorders of plant growth and development and physiological metabolism. Source control and biodegradation of soil MPs were considered effective approaches to decreasing their risks. Finally, existing studies on the shortcomings of the toxic effects of MPs on crops were recapitulated, and the future research direction of MPs was prospected, aiming to provide a reference for future research in the fields of agricultural soil ecosystems and pollution control of microplastics.

Variation law of micro-void distribution characteristics in early stage of spallation damage

The development trend of spallation damage mechanics is to construct a physical model that couples information with micro-mesoscale structure of materials, which also promotes the development of numerical calculation methods, experimental techniques and theoretical research. The mechanism responsible for plastic deformation and failure of structural metal materials at high strain rates is complex and ainfluenced by heterogeneities in the micro-mesoscale structure that comprises the distribution of grain boundaries, interfaces, and pre-existing densities voids. The distribution of these mesoscale heterogeneities can provide either strengthening behavior or void nucleation sites and influence spall failure behavior. Due to the lack of evolutionary information of micro-mesoscopic void distribution characteristics, the current spallation damage model is not only restricted in its application in extreme environments with high strain rates, high pressures, and shock, but also does not effectively provide some information about the correlation between material damage and final material fragmentation particle size, which is of very concern in engineering. Therefore, it is urgent to develop a spallation damage model that can reflect the variation law of micro-mesoscopic void distribution characteristics in damaged materials. The probability distribution function of void nucleation based on cosine function is given in this work by analyzing various influencing factors in the process of void nucleation, combining the characteristics of early void growth, and considering the convenience of analytical solution. The analytical calculation results of the new probability function of void nucleation are consistent not only with the results of the variation of void number with time calculated by molecular dynamics, but also with the experimental results of tantalum spallation in the early stage of damage development, that is to say, the new probability function of void nucleation can reflect the variation law of micro-void distribution characteristics in the early stage of spallation damage to a certain extent.

Effects of Superfine Cement on Fluidity, Strength, and Pore Structure of Superfine Tailings Cemented Paste Backfill

Advancements in mine tailings treatment technology have increased the use of superfine tailings, but their extremely fine particle size and high specific surface area limit the performance of superfine tailings cemented paste backfill (STCPB). This study investigates the effects of using superfine cement as a binder to enhance the fluidity, strength, and pore structure of STCPB. The influence of water film thickness (WFT) on STCPB performance is also examined. The results show that the cement-to-tailings ratio (CTR) and solid content (SC) significantly affect the spread diameter (SD) and unconfined compressive strength (UCS), following distinct linear/logarithmic and exponential trends, respectively. WFT has an exponential impact on SD and a non-linear effect on UCS, enhancing strength at low levels (0 μm < WFT < 0.0071 μm) and balancing hydration and flowability at moderate levels (0.0071 μm < WFT < 0.0193 μm) but reducing strength at high levels (WFT > 0.0193 μm). Additionally, superfine cement significantly improves the pore structure of STCPB by reducing porosity and macropore content. These findings provide valuable insights into optimizing STCPB for enhanced performance and sustainability in mine backfilling applications.

Effects of Fine Particle Size on the Characteristics of Coal Bottom Ash as an Environmentally Friendly Material in Concrete Production

In the current era, concern about the responsible disposal of industrial waste and its reuse has increased in all societies from the industry. Therefore, the researchers’ institution is focusing its efforts on developing more environmentally friendly products from recycled waste, particularly in the area of sustainable construction. For instance, one of recycled waste is Coal Bottom Ash (CBA), a by-product of coal combustion that is produced in large quantities from thermal power plants. The aims of this study to investigate the physical, chemical and element characteristics of CBA obtained from thermal power plant in Malaysia. Also, CBA compared with cement characteristics to be used as cement replacement in the concrete mixture. Therefore, numerous tests have been performed to investigate CBA’s physical and chemical characteristics. For physical properties such as specific gravity, particle size analysis, fineness modulus, bulk density and loss on ignition. For chemical properties such as X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) in an effort to obtain sustainable materials from thermal power plant waste. Based on the findings in this study, it can be concluded that CBA can be utilized as cement substitute in the production of concrete mixtures.

Ultrasonic Atomization as a Method for Testing Material Properties of Liquid Metals.

Ultrasonic atomization is an object of steadily increasing interest from metal powder manufacturers, both for additive manufacturing and powder metallurgy. Based on the analysis of available theoretical studies, simulations and experiments, it was noted that the average particle size after atomization and the final particle size distribution depend on the process parameters (e.g., frequency, amplitude) and the parameters of the atomized fluid (e.g., viscosity, surface tension). The objective of this study is to evaluate the feasibility of using ultrasonic atomization to study the properties of liquid metals. It attempts to close a gap in existing knowledge in searching for a new, possibly simple and cost-effective method to study the properties of liquid metals and clarify the relationship between ultrasonic atomization parameters (amplitude, frequency, metal spill on vibrating surface) and obtained atomization results (average particle size, particle size distribution, atomization time). Utilizing numerical modeling as a methodology, especially the finite element method, the possibilities of using ultrasonic atomization as an instrument to determine properties of liquid metals were considered as an introduction to a series of real experiments. Modeling was applied to liquids with different properties, atomized at a chosen specific constant frequency and amplitude. The results of the simulation are in line with the current state of knowledge about ultrasonic atomization. However, in the existing studies available to the authors, there are no data that can be compared directly, but indirect comparisons confirmed the conclusions of the preliminary literature analysis. The relationship between viscosity and surface tension and the average size of the atomization processes obtained in the simulation of particles was demonstrated, thus providing a tool for the development of the presented concept: ultrasonic atomization as a research method. Research and simulation results led to the final conclusion: ultrasonic atomization can be applied to study the properties of liquid metals and this will be the subject of further research and experimentation.

Proposed Method For Studying Radon Exhalation

Objective: The main objective was to test the closed radon exhalation methodology, with AlphaGuard radon detector, for different grain sizes of a granite rock sampled from central area of Belo Horizonte and propose experimental methods for its determination. Theoretical Framework: Natural radioactivity accounts for about 80% of the average annual radiation dose humans receive, primarily due to primordial radionuclides in the Earth’s crust. The World Health Organization (WHO) recommends national radon (Rn) exposure mapping programs based on geological studies due to the significant contribution of Rn gas to annual radiation doses. Studies indicate that granitic and metamorphic rocks, black shales, phosphate rocks, and some carbonate rocks are common radon sources. Rn is generated in soil and migrates through soil pores, entering buildings through cracks and openings. Rn transport is influenced by factors like local geology, humidity, and temperature. Method: The study tested radon exhalation from granite samples in center of Belo Horizonte using a proposed method with AlphaGuard in an exhalation circuit. Results and Discussion The studied method proved to be effective with particle sizes up to 16#. For very fine particle sizes, the air flow is hampered and therefore reduces the effectiveness of transporting the radon-filled gas. Research Implications: The implications of this research are discussed, providing insights into radon exhalation method in a closed circuit and its challenges. This study contributes to literature by studing exhalation rate is vital for estimating radiation risk from many kinds of materials and the indoor radon.

Wear Behaviour of Nickel Coatings Reinforced by Recycled Quarry Dust: Influence of Current Density

Nickel coatings incorporated with quarry dust were synthesized through direct current electrodeposition from a nickel Watt’s bath. The study explored the effects of varying current densities on the surface morphology and wear behaviour of the nickel-quarry dust (Ni-QD) composite coatings deposited on a high-speed steel (HSS) substrate. Quarry dust was chosen as a reinforcement material due to its high silica and alumina content, which enhance the properties of the coating. To achieve finer particle size, the quarry dust was subjected to ball milling before electrodeposition. The study tested a range of current densities from 2 to 8 A/dm², as different current densities produce different results. The composite coatings were characterized using a Scanning Electron Microscope (SEM) and their wear resistance was evaluated through pin-on-disk test. The results indicated that increasing the current density enhanced the wear resistance of the coatings. Coatings produced at high current densities displayed a colony-like structure, demonstrating the impact of deposition conditions on colony size relative to current density. Ni-QD composite coatings created at 6 and 8 A/dm² resulted in smoother and narrower wear scars with minimal scratching, attributed to the low surface roughness of the coatings.

Assessing the Impact of Surface Blast Design Parameters on the Performance of a Comminution Circuit Processing a Copper-Bearing Ore

Open-pit mining remains the dominant method for copper extraction in current operations, with blasting playing a pivotal role in the efficiency of downstream processes such as loading, hauling, crushing, and milling. This study assesses the impact of surface blast design parameters on the performance of a comminution circuit processing a copper-bearing ore. The analysis focuses on important design parameters such as burden, spacing, stemming, and powder factor, evaluating their influence on the fragment size distribution and downstream comminution circuit performance. Using the Kuz-Ram model, four novel blast designs are compared against a baseline to predict the size distribution of rock fragments (X80). Key performance indicators throughput and specific energy consumption are calculated to evaluate the comminution circuit performance. Results demonstrated that reducing the X80 from 500 mm to 120 mm led up to a 20% increase in throughput and a 29% reduction in total specific energy consumption. Furthermore, achieving finer particle sizes through more intensive blasting contributed to a reduction in total operating costs by up to 12%. These findings provide valuable insights for optimizing blast design to improve comminution circuit performance, contributing to sustainable mining practices by reducing energy consumption, operating costs, and the environmental footprint of mining operations.

Characterization of Physical and Chemical Properties of Multi-Source Metallurgical Dust and Analysis of Resource Utilization Pathways

Steel metallurgical dust, characterized by a substantial output, minute particle size, and intricate composition, poses a considerable risk of environmental contamination while simultaneously embodying an exceptionally high potential for recycling. To achieve its resource utilization, chemical analysis, particle size analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy, and water leaching methods were employed to investigate the chemical compositions, particle size distributions, phase compositions, and microscopic morphologies of blast furnace bag dust, sintering dust, converter fine dust, and electric arc furnace dust from steel plants. The results indicate that the four types of dust have extremely fine particle sizes, with the main distribution range of particle size being less than 100 μm. The main constituent element is Fe (19–56%), and it also contains Zn (1.4–33.5%), Pb, K, C, and other valuable elements. Alkali metals in blast furnace bag dust and sintering machine head dust existed mainly in the form of chloride. The zinc phases in sintering machine head dust and converter fine dust were ZnFe2O4, and the zinc phases in blast furnace bag dust were ZnCl2 and ZnFe2O4. Zinc in electric furnace dust was composed of ZnO and ZnFe2O4, accounting for 70.31% and 23.12%, respectively. There are significant differences in the types and contents of valuable elements among various dusts, making it difficult to achieve full-scale recovery through a single process. In view of this, a process of “in-plant recycling of harmless dusts—collaborative treatment of harmful dusts” has been proposed. Based on the characteristics of metallurgical dusts, multiple processes are used for collaborative treatment (using hydrometallurgical and pyrometallurgical methods), which can not only directly recover iron resources from dusts within the plant, but also avoid the waste of valuable elements such as Zn, Pb, K, Na, etc. It is hoped that the above work can provide a reference for steel enterprises to achieve full-scale and high value-added treatment of metallurgical dusts.

Rheology and early age evaluation of 3D printable cement-limestone filler pastes with nanoclays and methylcellulose

Nanoclays (NC) are known to increase the structural build-up of cement-based materials (CBM) while methylcellulose (MC) is used to increase open time and workability, helping to prevent cold joints in 3D Printing applications. The combination and compatibility of both NC and MC could lead to the design of new 3D printable CBM able to tackle all the manufacturing process requirements. The aim of the study is to evaluate the effect of sepiolite nanoclay and MC on rheology and early age (EA) parameters of cement-limestone filler pastes for 3D printing applications, identifying fresh structural build up and setting mechanisms. The effect of two cement types with coarser and finer particle size distribution (CEM I 42.5-R and CEM I 52.5-R, respectively) was considered. Pastes rheology was characterized by Cone Penetration Test (CPT) and Dynamic Shear Rheometer (DSR). EA was monitored by P- and S-waves Ultrasonic Pulse Velocity (UPV), internal temperature, capillary pressure and drying shrinkage. Fresh Shear Yield Stress (τ0) and shear elastic modulus (G), effective thixotropy (Athix), critical strain (γcrit) and their evolution over time were calculated form CPT and DSR experimental results. A limit of usability was defined for τ0 up to 20 kPa for CPT with a 30º tip cone. Although pastes with both NC and MC showed thixotropy, NC reduced γcrit while MC strongly increased it. NC significantly increased Athix and ΔG with coarser particle size cement when compared to the finer cement. MC delayed hydration reaction and setting, while NC did not affect early age stages. On the other hand, combining NC and MC increased superplasticiser demand and reduced effective thixotropy (Athix). Finally, an integrated overview of the physical and chemical mechanisms involved in rheology and early age properties of cement-based systems and the key experimental parameters for their identification was proposed.

Utilization of Steel Slag as Partial Replacement of Fine Aggregate Material in Concrete

Concrete is the most used building material in the world. As a sustainable approach in this project explores the potential benefits of incorporating steel slag sand in concrete mixtures. The objective is to study the mineralogical properties of cement, steel slag to study the strength parameter like compressive strength at 7, 14, 28 days for all mix proportions. This project investigates the utilization of the replacement of fine aggregate with steel slag sand in concrete mixes. The study evaluates the impact of these components on the mechanical properties of concrete through compression tests conducted over varying time intervals. Results indicate that as the proportion of steel slag sand increase, there is a corresponding enhancement in compressive strengths of the concrete mixes. Mix 5, containing the highest proportions of these components with 50% M- Sand and Steel slag sand, consistently demonstrates superior mechanical properties compared to other mixes, showcasing an impressive increase in compressive strengths. This highlights the effectiveness of finer particle sizes and improved packing density.

Use of Soil Remineralizer to Replace Conventional Fertilizers: Effects on Soil Fertility, Enzymatic Parameters, and Soybean and Sorghum Productivity

The reliance on soil acidity correctives and mineral fertilizers poses a threat to food production due to the finite nature of these resources and their susceptibility to price volatility from importation. Soil remineralizers have emerged as a sustainable alternative. This study assessed silicate agrominerals as soil remineralizers to replace limestone, gypsum, and conventional fertilizers in a no-tillage system. Conducted in a tropical climate on sandy/medium-textured Ultisol, twelve treatments (combinations of liming, gypsum, mineral fertilization, and remineralizer) were tested for their effects on soybean and sorghum agronomic traits. Applying a remineralizer at 2500 kg ha−1 enhanced soybean productivity by 15% and sorghum by 35% in succession, along with increases in P, S, Ca, Mg, sum of bases (SB), cation exchange capacity (CEC), base saturation (V%) in the 0–0.20 m layer and organic matter in the 0–0.40 m layer, benefiting soil microbiological parameters, with the treatment combining all four products improving soil fertility; however, for better crop productivity, split applications appear to be an alternative to avoid nutrient imbalance. Due to the finer particle size of the remineralizer, which allows faster nutrient release, further research is recommended to investigate the long-term impacts on soil microbiota dynamics, optimal doses and combinations, and economic viability across various soil types and climates.

Fabrication of CuO NP for NO2 Gas Sensing

NO2 is a very dangerous gas that is mainly emitted from fossil fuels and is a major cause of air pollution. It has environmental problems cause by acid rain and has a bad effect on human health. In this study, mesoporous CuOx nanoparticles (NPs) were successfully synthesized using a low-temperature sol–gel method. Subsequently, the synthesized NPs were annealed at temperatures of 250, 350, and 450 °C. The Properties of the synthesized samples showed that the size of NPs increased with increasing annealing treatment, while the surface area decreased. The samples annealed at 250°C/2h exhibited significantly higher surface area compared to the samples annealed at 350°C and 450°C, thanks to their finer particle size and mesoporous properties. Resistive gas sensors incorporating these samples were successfully fabricated and tested for sensitivity towards both NO2 (oxidizing gas) and H2S (reducing gas) at 200 °C. The sensor with the mesoporous CuOx NPs annealed at the lowest temperature (250 °C) exhibited an enhanced response to NO2 gas but no response to H2S. The strong response to NO2 gas is considered to be due to the high surface area of the sensing layer which provides plenty of adsorption sites for gas molecules and the oxidizing nature of NO2 gas with high affinity to electrons. These findings highlight the effectiveness of the sol–gel method in synthesizing CuO NPs for gas sensing, as well as the need for optimizing the annealing temperature to maximize the sensor response.

Fabrication of Thin Li6PS5Cl Separators for All-Solid-State Lithium-Ion Batteries

Thin sulfide separators for all-solid-state batteries are crucial to obtain low internal battery-cell resistances, i.e. good battery-cell performances, and high energy densities [1]. A two-dimensional sulfide separator sheet consists commonly of sulfide powder and a polymeric binder. The components are dispersed in a solvent and casted to a given sacrificial substrate. Current challenges for thin separator fabrication include either (1) high costs for commercial sulfide material with very fine particle sizes (<5 µm) or (2) very large particle size distributions (<1 to >100 µm) for “lower-cost” commercial sulfide powders. Since the separator thickness is limited to the diameters of the largest particles, sulfide particles are preferred to be smaller than ~5 µm at an affordable price.In this work, we have produced thin two-dimensional sulfide separator sheets with thicknesses of 20 µm from commercial “lower-cost” Li6PS5Cl material. The powder was wet-ball-milled and dried before it was subjected to paste fabrication and separator casting. Using x-ray diffraction and electrochemical impedance spectroscopy, it was proven that crystal structure and Li-ion conductivities of Li6PS5Cl were unhampered from the mechanical treatment. Secondary electron images of the separator cross-sections revealed ultra-fine particles and the strikingly low separator thickness of 20 µm. An example for such a separator is visible in the attached figure: (a) Photograf of the casted layer on PET foil, (b) SEM top view, (c), cross-section (d) and magnified cross-section of a compressed separator.In the next step, the separator was connected with the (composite) electrodes. Here, we investigated two different approaches to achieve a good mechanical contact and therefore a good electrochemical performance. On the one hand we transferred the separators onto the electrodes by uniaxially or isostatically pressuring. On the other hand we investigated a direct coating of the separator slurry onto metal or composite electrodes.[1] Randau, S., Weber, D.A., Kötz, O. et al. Benchmarking the performance of all-solid-state lithium batteries. Nat Energy 5, 259–270 (2020). https://doi.org/10.1038/s41560-020-0565-1 Figure 1

A Novel Wet Synthesis Method of High-Conductivity Sulfide Solid Electrolytes with Controlled Particle Size for All-Solid-State Batteries

Growing safety concerns regarding commercial lithium-ion batteries arise from the use of flammable organic liquid electrolytes. Consequently, all-solid-state batteries (ASSBs), free from such electrolytes and therefore posing no fire risk, are attracting significant attention as the next-generation battery system. Among various solid electrolytes (SEs), sulfide-based SEs stand out as promising candidates for commercialization due to their high ionic conductivity and superior processability. For the commercialization of ASSBs, a scalable and efficient wet synthesis process for mass production of solid electrolytes is essential.In previous research, we developed a novel method for preparing bulk-type argyrodite Li6PS5Cl (LPSCl) SEs with high ionic conductivity approaching 2 mS cm-1 using solution-phase synthesis with an additive and no high-energy ball-milling processes. Additionally, we investigated various solvents to understand the relationship between solvent properties and the purity of LPSCl SEs, finding that the characteristics of organic solvents play a significant role in lithium polysulfide formation. Despite these advancements, limitations in large-scale SE production may arise due to the use of petrochemical-derived toxic solvents. Therefore, we explored scalable production of cost-effective LPSCl-based sulfide SEs with high ionic conductivities exceeding 2 mS cm-1 using various green and sustainable solvents. However, the wet synthesis method introduced previously often produces SEs with large particle sizes, necessitating additional pulverization processes. This leads to increased costs and time, posing limitations to commercialization.This study introduces a novel, scalable, and cost-efficient wet synthesis approach for producing superionic conductive sulfide-based SEs. This pioneering process enables the creation of fine solid electrolyte particles by controlling the nucleation rate and strategically introducing Cl excess to enhance ionic conductivity. The synthesized Li5.5PS4.5Cl1.5 SE features a uniform size distribution (with an average particle diameter of 7 μm) and a high ionic conductivity of 4.98 mS cm-1, comparable to those produced by dry processes. The ability to control particle size allows the direct integration of these SEs with electrodes, eliminating the need for additional pulverization and facilitating the commercialization of ASSBs. The simulation results, including density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations, confirm that the experimental data trends align with theoretical predictions. By utilizing green and sustainable solvents, we significantly reduced the environmental footprint of the production process, highlighting the importance of environmentally friendly methods in the sustainable commercialization of ASSBs.In conclusion, the novel wet synthesis method introduced in this study represents a major advancement in the field of ASSBs. By achieving high ionic conductivity through Cl excess and ensuring fine particle size control, we have addressed key barriers to commercialization. The ability to integrate these SEs directly with electrodes without additional pulverization processes further enhances the practical applicability of this method. As ASSBs continue to gain traction as the next-generation battery system, our findings provide a robust foundation for future developments and large-scale production. This study not only contributes to the technical advancement of battery technology but also underscores the importance of sustainable practices in the quest for high-performance energy storage solutions.

One-Pot Synthesis of (CrMnFeCoNi)Ox High-Entropy Oxides for Efficient Catalytic Oxidation of Propane: A Promising Substitute for Noble Metal Catalysts.

The efficient catalytic oxidation of propane, as a short-chain alkane, remains challenging in environmental catalysis. High-entropy oxides (HEOs) exhibit advantages in abundant and well-dispersed elemental composition, exceptional thermal stability, and enriched lattice defects. Herein, (CrMnFeCoNi)Ox HEO catalysts are successfully synthesized by using a continuous hydrothermal flow synthesis (CHFS) route, without any subsequent calcination processes. This route yields HEOs with fine particle sizes, high specific surface areas, and abundant near-surface lattice oxygen compared to the traditional coprecipitation method. Notably, the propane conversion over the CHFS-made (CrMnFeCoNi)Ox HEO reaches 90% at 255 °C, with an apparent activation energy of 53.2 kJ/mol, mainly attributed to its enriched lattice oxygen and enhanced oxygen mobility that prevent the accumulation of acetates and the consequent occupation of active sites. In comparison to commercial Pt/Al2O3 and Pd/Al2O3, (CrMnFeCoNi)Ox HEO demonstrates exceptional activity and can maintain long-term stability under high-temperature (upon 650 °C) and moisture-rich conditions (at 2-10 vol %). These attributes highlight its potential as a promising substitute for noble metal catalysts in industrial applications.

A Critical Review of the Technical Characteristics of Recycled Brick Powder and Its Influence on Concrete Properties

This paper presents a systematic overview of the applications of RBP as a substitute for cement. Initially, the fundamental properties of RBP, including physical properties, chemical compositions, and morphology, are discussed. Subsequently, the effects of RBP on various aspects of cement-based materials, such as fresh properties, shrinkage behavior, hydration, microstructure, strength development, and durability, are thoroughly reviewed. The findings of this study reveal that waste brick powder exhibits pozzolanic activity and can be used to partially replace cement in concrete formulations. However, its relatively high water absorption and irregular shape increase the water demand and, thus, reduce the rheological properties. The incorporation of RBP with 10–20% or finer particle sizes can refine the pore structure and promote the formation of hydration products. However, replacements of RBP greater than 25% can lead to adverse effects on the mechanical properties, frost resistance, and carbonation resistance of cementitious composites. Therefore, to enhance the effectiveness of RBP, measures such as improving fineness, incorporating mineral admixtures, adjusting curing conditions, and applying nano- or chemical modifications are necessary. This study provides valuable technical support for promoting the sustainable preparation of construction materials, which holds important environmental and economic implications.

Wear energy approach for evaluation of tribological properties of Cr2O3-TiO2 coating

Abstract In the present work, Cr2O3-TiO2 ceramic coating was deposited by atmospheric plasma spray (APS) method. Tribological response of coating was thoroughly examined using two different sizes of SiC abrasives under four distinct loads. Coatings were characterized by Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X-Ray Diffraction, Raman spectroscopy and X-Ray Photoelectron Spectroscopy. The coating experienced 31–40% lower friction coefficient at coarser particle size whereas 1.4–1.6 times lower wear rates were obtained at finer particle size. Results were explained on the basis of adhesion-abrasion components of friction. Consequences of formation of a tribo-oxide film and its implications on specific energy for material removal along with wear mechanisms are also discussed. A modified wear energy parameter (WEP) is used and showed good correlation with experimentally measured wear rates and friction coefficient of the coating.

Genotype and grain pretreatment effects on digestibility of sorghum proteins in the Ethiopian fermented bread

AbstractBackground and ObjectivesSorghum is the principal food source for smallholder farmers in Sub‐Saharan Africa. Animal proteins are beyond economic reach, and only few food legumes are well‐adapted in major sorghum‐growing regions. Hence, sorghum serves as the primary source of protein and calories. However, the low digestibility of its proteins renders the communities vulnerable to protein malnutrition. Several factors, including genotypes and processing methods, have been shown to affect the digestibility of proteins in sorghum food products. The objective of this study was to investigate the impact of grain pretreatment on the protein digestibility of Ethiopian fermented flatbread.FindingsThe effect of four grain pretreatment processes: decortication, sprouting, parching, and untreated control was compared using four diverse sorghum genotypes milled to medium (2 mm) and fine (0.5 mm) particle sizes. The in‐vitro protein digestibility (IVPD) was significantly lower in the parched samples compared to the unprocessed control, while sprouting significantly increased IVPD. Decortication appears to have no impact on IVPD. Finer particle size tended to enhance IVPD in all genotypes and for all pretreatement methods. The treatments had no significant effect on protein content except the sprouting consistently but marginally increased total protein.ConclusionsSprouting sorghum grains can significantly improve the protein digestibility of fermented breads. Given that it involves little cost, the process can be readily adopted by the local community, provided that they are educated about the impact of protein deficiency on the health and productivity of the community.Significance and NoveltyLow‐cost grain pretreatment procedures such as sprouting can have a significant impact on the availability of nutrients, especially protein, the most limiting nutrient in smallholder communities. Combining the procedure with genetically enhanced varieties and improved cropping systems that integrate food legumes can significantly enhnace protein nutrition for smallholder farmers.

Roles of superabsorbent polymers (SAPs) and palm oil fuel ash (POFA) on the strength, cost analysis and CO2 emission of lightweight concrete: Comparison with aluminum-based aerated concrete

This work investigated the effects of superabsorbent polymers (SAPs) as pore-forming agent and palm oil fuel ash (POFA) as sand replacement (0–100 % by weight) on the strength, economic feasibility, and CO2 emissions for lightweight concrete production. The product properties were compared with the traditional aerated concrete (with aluminum powder), which aimed to shed light on the use of SAPs and POFA for manufacturing a more sustainable lightweight concrete. The use of POFA to replace sand increased the cost of production by approximately 1–7% and CO2 emissions by approximately 3–12 % due primarily to the transportation of the POFA from the oil palm fuel power plant, which could be avoided if produced on site of or near the power plant. The use of SAPs in the preparation of the lightweight concrete led to a reduced compressive strength compared to the aerated concrete, especially in the autoclaved samples, calculated as 15–33 % for 28 days and 44–56 % for autoclaved curing, possibly due to a collapse of the porous structure under high temperature and pressure. These drawbacks could be eliminated if the natural SAPs in the form of fine particle size were treated with Ca2+ in agro-waste ash so as to facilitate and enhance the pozzolanic reaction during the curing phase. The fossil-based SAPs could then be replaced with the organic-based ones, which would be a more sustainable construction material for a lower-carbon society. However, further investigations into other aspects of these materials should be conducted.