Varying Particle Size Research Articles

Influence of Particle Size on Compressed Earth Blocks Properties and Strategies for Enhanced Performance

In the context of sustainable building development, Compressed Earth Blocks (CEBs) have garnered increasing attention in recent years owing to their minimal environmental and economic impact. However, owing to the inherent diversity of raw soil and the production process’s reliance on expertise, the properties of these blocks are subjected to multifaceted influences. Among these, the significance of soil particle size variation often remains overlooked, leaving its impact ambiguous. This study endeavours to address this gap in existing research by delving into this aspect. Two distinct batches of CEBs were produced by adjusting the grain size curve of a single type of sieved soil with different maximum mesh openings: 2 mm for R1 CEBs and 12.5 mm for R2 CEBs. Experimental results reveal significant differences in thermophysical characteristics: on average, R1 blocks show superior thermal performance, boasting a 23% reduction in thermal conductivity compared to R2 blocks, and are lighter, with an 8% decrease in dry bulk density. Although no significant changes in mechanical parameters were observed, finer-structured R1 blocks showed a 25% greater tendency to absorb water due to changes in their porous structure. This study sheds light on the sensitivity of thermal parameters to changes in soil particle size and shows that blocks with finer particles exhibit poorer heat conduction and heat diffusion. Besides providing new insights into the literature, this research also provides a strategic approach to optimise the thermophysical properties of CEBs. By understanding the influence of particle size, researchers and practitioners can now develop strategies to enhance these properties and improve the overall performance of CEBs.

Dynamic in situ measurement of axial segregation of E-CAT particles in a bubbling fluidized bed

The present paper summarizes comprehensive in situ measurements of the temporal segregation/mixing behavior of the non-spherical Geldart B and D E-CAT particles mixture in a bubbling fluidized bed. The experiments are performed for both unsieved and sieved E-CAT particles with varying particle size distribution width and at the fluidization velocity ranging from 1.3 to 5Umf. The high-speed pressure and image data were used to provide time-resolved quantification of dynamic expanded bed height and pressure drop during the experiment. In parallel, a hybrid machine learning-aided image processing algorithm has been developed for quantifying the instantaneous particle size distribution at varying axial locations. Results reveal that the segregation exists only at low fluidization velocities (1.3 and 1.6Umf) for unsieved cases with a wider size distribution. In contrast, particles with a narrower distribution exhibited well-mixed behavior for the full range of tested gas velocities. The segregation intensity and spatial extent were found to correlate with particle size distribution width and fluidization velocity, respectively. In addition, by analyzing pressure, expanded bed height, particle size and motion, and bubble characteristics, we provided a comprehensive multi-scale dynamic view of the segregation process. This in-depth understanding of the process, coupled with the time-resolved datasets obtained, can be instrumental for benchmarking numerical models in solid–gas multiphase flows and for optimizing the design of fluidized beds.

Effects of different concentrations and particle sizes of nanoplastics on gut microbiology, metabolism, and immunity in Chiromantes dehaani

This study investigated the effects of nanoplastics (NPs) of varying particle sizes (75, 500, and 1000 nm) and concentrations (2.5 and 10 mg/L) on the gut health of Chiromantes dehaani. The experimental groups included a control (Cg0), and varying combinations of particle size and concentration. Our results showed that 75 nm NPs were more likely to enhance pathogenic bacterial growth than other sized NPs. Compared with CK, Low NPs concentrations (2.5 mg/L) raised total cholesterol (T-CHO) levels in the gut, while high concentrations significantly decreased both triglyceride (TG) and T-CHO levels (p < 0.05). The enzymatic activities of intestinal lipase and amylase were inhibited by NPs exposure, with greater inhibition at higher NPs concentrations. The 500 nm NPs exhibited a notably higher inhibitory effect than the 75 and 1000 nm NPs (P < 0.05). In terms of apoptosis, NPs exposure led to reduced mRNA expression of Bcl2 and increased expression of Caspase-3, Caspase-8, and Caspase-9, indicating an induction of apoptosis. This effect was more pronounced at higher NPs concentrations, with 75 nm NPs more likely to induce apoptosis in intestinal cells than 500 nm and 1000 nm NPs. Moreover, NPs triggered intestinal inflammatory responses, evidenced by the increased mRNA expression of TNF-β, TNF-α, IL1β, IL6, and IL8, and the decreased expression of IL10. High NPs concentrations were more likely to induce intestinal inflammation, with 500 nm NPs imparting the strongest effect. In summary, the study demonstrated that NPs, and particularly those at higher concentrations, disrupted the gut environment of C. dehaani by altering the microflora, reducing microbial diversity, inhibiting digestion and metabolism, inducing apoptosis, and triggering inflammation. Among the sizes of NPs tested, 500 nm NPs had the most significant adverse impact on digestion, metabolism, and inflammation, while 75 nm NPs most strongly induced apoptosis in C. dehaani's intestinal cells.

Experimental Study on the Morphology of Snow Crystal Particles and Its Influence on Compacted Snow Hardness

In their natural state, snow crystals are influenced by the atmosphere during formation and multiple factors after landing, resulting in varying particle sizes and unstable particle morphologies that are challenging to quantify. The current research mainly focuses on the relationship between the porosity of compacted snow samples or qualitatively describes snow crystals and their macroscopic physical properties, ignoring that the significant differences in the morphology of snow crystals also affect their physical properties. To quantitatively evaluate the morphology of snow crystals, we employed optical microscopy to obtain digital images of snow crystals in Harbin, utilizing the Sobel and Otsu algorithms to determine the equivalent particle size and fractal dimension of individual snow particles. In addition, the hardness of snow with a density of 0.4 g/cm3 was measured through a penetration test, with an analysis of its correlation relative to particle size and fractal dimension. The results indicated the fractal dimension as an effective parameter for characterizing particle shape, which decreased rapidly over time and then fluctuated within the range of 1.10 to 1.15. During the initial period, natural snow crystals broke down rapidly, leading to an increase in the percentage of natural snow crystals with an equivalent particle size of 0.2–0.4 mm up to 51.86%. After three days, the sintering effect between snow crystals was enhanced, resulting in an even distribution of the equivalent particle size. Finally, multiple linear regression analysis showed a positive correlation between compacted snow hardness and fractal dimension, with a negative correlation between compacted snow hardness and equivalent particle size. These findings offer valuable technical support and data reference for exploring the relationship between snow’s mechanical properties and its microscopic particle shape.

The effect and mechanism of variable particle size microplastics and levofloxacin on the neurotoxicity of Rana nigromaculata based on the microorganism-intestine-brain axis

Microplastics (MPs) usually appear in the aquatic environment as complex pollutants in combination with other environmental pollutants, such as levofloxacin (LVFX). After a 45-day exposure to LVFX and MPs with different particle sizes at environmental levels, LVFX was neurotoxic to Rana nigromaculata tadpoles. The order of the effects of the exposure treatment on tadpole behavior was: LVFX-MP3>LVFX-MP1>LVFX-MP2 ≥ LVFX. Results of transcriptome analysis of tadpole brain tissue showed that LVFX in combination with 0.10 and 10.00 μm MP interferes with the nervous system through the cell adhesion molecules pathway. Interestingly, the order of effects of the co-exposure on oxidative stress in the intestine was inconsistent with that of tadpole behavior. We found that Paraacteroides might be a microplastic indicator species for the gut microbiota of aquatic organisms. The results of the targeted metabolism of neurotransmitters in the intestine suggest that in the LVFX-MP2 treatment, LVFX alleviated the intestinal microbiota disorder caused by 1.00 μm MP, by regulating intestinal microbiota participating in the TCA cycle VI and gluconeogenesis and tetrapyrrole biosynthesis I, while downregulating Met and Orn, and upregulating 5HIAA, thereby easing the neurotoxicity to tadpoles exposed to LVFX-MP2. This work is of great significance for the comprehensive assessment of the aquatic ecological risks of microplastics-antibiotic compound pollutants.

Demineralization of fine and ultrafine coal particles of Talcher area by oil agglomeration technique

ABSTRACT The costs of fine coal cleaning cannot surpass the fetched recuperation within the included clean coal to be financially practical. In this present study, percentage of ash and yield of the agglomerated coal, Percentage of OMR (Organic matter recovery) and AR (Ash rejection) have been calculated for the coal slurry of size ranges from 0.07 mm to 0.3 mm. The result of the three parameters (ash, yield, and fixed carbon) were calculated by varying particle size, type of oil (sunflower oil, castor oil, and kerosene oil), amount of oil doses and the speed of the impeller. The results show an increase in value of fixed carbon percentage, decrease in the value of ash percentage of the agglomerated recovered clean coal. But the value of yield and quality of the recovered clean coals are almost around 10% and more than 95% and also are independent of the agitation speed of the impeller. The estimated values of ash rejection by the proposed techniques were between 97% and 99% with an increase in the calorific value of 88%. which is a promising technique and can be applied for the pilot scale unit.

Water Spinach (Ipomoea aquatica F.) Effectively Absorbs and Accumulates Microplastics at the Micron Level—A Study of the Co-Exposure to Microplastics with Varying Particle Sizes

The absorption of microplastics (MPs; size &lt; 5 mm) by plants has garnered increasing global attention owing to its potential implications for food safety. However, the extent to which leafy vegetables can absorb large amounts of MPs, particularly those &gt; 1 μm, remains insufficiently demonstrated. To address this gap in knowledge, we conducted water culture experiments using water spinach (Ipomoea aquatica F.) as a model plant. The roots of water spinach were exposed to a mixed solution that contained fluorescently labeled polystyrene (PS) beads with particle sizes of 200 nm and 1 μm for 10 d. We utilized laser confocal scanning microscopy and scanning electron microscopy to record the absorption, migration, and patterns of accumulation of these large particle sizes of MPs within water spinach. Our findings revealed that micron-sized PS beads were absorbed by the roots in the presence of submicron PS beads and subsequently transported through the exosomes to accumulate to significant levels in the leaves. Short-term hydroponic experiments further indicated that high concentrations of PS bead solutions significantly inhibited the growth of water spinach owing to their large specific surface area that hindered the uptake of water and nutrients by the roots. In conclusion, both sizes of PS beads were found to be absorbed by water spinach, thereby increasing the risk associated with direct human consumption of microplastics in fruits and vegetables. This study provides valuable scientific insights to assess the pollution risks related to fruits and vegetables, as well as ensuring vegetable safety.

Boosting Bulk Oxygen Transport with Accessible Electrode Nanostructure in Low Pt Loading PEMFCs.

Despite the high potential for reducing carbon emissions and contributing to the future of energy utilization, polymer electrolyte membrane fuel cells (PEMFCs) face challenges such as high costs and sluggish oxygen transport in cathode catalyst layers (CCLs). In this study, the impact of pore size distribution on bulk oxygen transport behavior is exploredby introducing nano calcium carbonate of varying particle sizes for pore-forming. Physicochemical characterizationsfor are employed to examine the electrode structure, while in situ electrochemical measurements are used to scrutinize bulk oxygen transport resistance, effective oxygen diffusivity ( ) and fuel cell performance. Additionally, the CCLs are constructed with aid of Lattice Boltzmann method (LBM) simulations and for CCLs with different pore size distribution are calculated. The findings reveal that initially increases and then decreases as the most probable pore size increases. A "sphere-pipe" model is proposed to describe practical bulk oxygen transport in CCLs, highlighting the significant role of not only the pore size of secondary pores but also the number of primary pores in bulk oxygen transport.

Toward Polydisperse Flows With mfix-exa

Abstract In the presence of large size disparities, single-grid neighbor search algorithms lead to inflated neighbor lists that significantly degrade the performance of Lagrangian particle solvers. If Eulerian–Lagrangian (EL) frameworks are to remain performant when simulating realistic systems, improved neighbor detection approaches must be adopted. To this end, we consider the application of a multigrid neighbor search (MGNS) algorithm in the mfix-exa software package, an exascale EL solver built upon the AMReX library. Details regarding the implementation and verification of MGNS are provided along with speedup curves for a bidisperse mixing layer. MGNS is shown to yield up to 15× speedup on CPU and 6× speedup on GPU for the problems considered here. The mfix-exa software is then validated for a variety of polydisperse flows. Finally, a brief discussion is given for how dynamic MGNS may be completed, with application to spatially varying particle size distributions.

Organic matter influence on ooid formation: New insights into classic examples (Great Salt Lake, USA; Triassic Germanic Basin, Germany)

ABSTRACTOoids are coated grains composed of a tangential or radial cortex growing around a nucleus. They are common in carbonate deposits of almost any geological age and provide insights into environmental conditions. However, abiotic or biotic factors influencing their formation remain unclear. This study aims to advance current understanding of ooid formation with a multi‐analytical approach (for example, field emission scanning electron microscopy, Raman spectroscopy and micro X‐ray fluorescence) to classic examples from Great Salt Lake, USA, and the Lower Triassic Germanic Buntsandstein Basin, Germany. Both of these deposits represent hypersaline shallow‐water environments where ooids are closely associated with microbial mats. Great Salt Lake ooids are dominantly 0.2 to 1.0 mm in size, ellipsoidal to subspherical in shape, composed of aragonite and contain organic matter. Germanic Buntsandstein Basin ooids are mainly ≤4 mm in size, spherical to subspherical in shape, composed of calcite and currently contain little organic matter. Despite the differences, both ooids have the same cortex structures, likely reflecting similar formation processes. Some Great Salt Lake ooids formed around detrital grains while others exhibit micritic particles in their nuclei. In Germanic Basin ooids, detrital nuclei are rare, despite the abundance of siliciclastic particles of various sizes in the host rocks. Germanic Basin deposits also include ‘compound ooids’, i.e. adjacent ooids that coalesced with one another during growth, suggesting static in situ development, which is supported by the lack of detrital grains as nuclei. Germanic Basin ooids also grew into laminated microbial crusts with identical microstructures, further indicating a static formation. Such microbial crusts typically form through mineral precipitation associated with organic matter (for example, extracellular polymeric substances), suggesting a similar formation pathway for ooids. The inferred key‐role of organic matter is further supported by features in radial ooids from the Great Salt Lake, which commonly exhibit, from their nuclei towards their surface, increasing organic matter contents and decreasing calcification.

Influence of polyethylene terephthalate (PET) microplastic on selected active substances in the intramural neurons of the porcine duodenum

BackgroundCurrently, society and industry generate huge amounts of plastics worldwide. The ubiquity of microplastics is obvious, but its impact on the animal and human organism remains not fully understood. The digestive tract is one of the first barriers between pathogens and xenobiotics and a living organism. Its proper functioning is extremely important in order to maintain homeostasis. The aim of this study was to determine the effect of microplastic on enteric nervous system and histological structure of swine duodenum. The experiment was carried out on 15 sexually immature gilts, approximately 8 weeks old. The animals were randomly divided into 3 study groups (n = 5/group). The control group received empty gelatin capsules once a day for 28 days, the first research group received daily gelatin capsules with polyethylene terephthalate (PET) particles as a mixture of particles of various sizes (maximum particle size 300 µm) at a dose of 0.1 g/animal/day. The second study group received a dose ten times higher—1 g/animal/day.ResultsA dose of 1 g/day/animal causes more changes in the enteric nervous system and in the histological structure of duodenum. Statistically significant differences in the expression of cocaine and amphetamine regulated transcript, galanin, neuronal nitric oxide synthase, substance P, vesicular acetylcholine transporter and vasoactive intestinal peptide between control and high dose group was noted. The histopathological changes were more frequently observed in the pigs receiving higher dose of PET.ConclusionBased on this study it may be assumed, that oral intake of microplastic might have potential negative influence on digestive tract, but it is dose-dependent.

Numerical simulation on adsorption of CO2 using K2CO3 particles in the bubbling fluidized bed

AbstractWith the increase of greenhouse gas emissions, global warming has become an urgent problem, and the use of solid adsorbents to capture CO2 gas in flue gas has attracted more and more attention. In this study, the process of CO2 capture by K2CO3 particles in the bubbling fluidized bed (BFB) is numerically simulated with Eulerian–Eulerian(E–E) two fluid model incorporating with the kinetic theory of granular flows (KTGF). The results are verified through a detailed comparison with experimental data from Ayobi et al. Furthermore, Regarding the fundamental factors influencing CO2 adsorption rate is revealed, diminishing the inlet gas superficial velocity and augmenting the particle size of the solid adsorbent both contribute to improve adsorption performance. Specifically, the adsorption rate increases from 76.7% to 81.7% at the gas superficial velocity reducing from 1.10 to 0.71 m/s, while the adsorption rate from 77.6% to 79.7% with the particle size ranging from 400 to 600 μm. Additionally, the study delves into an exploration of fluid dynamic characteristics pertaining to gas particles within the bubbling fluidized bed while systematically considering varied inlet gas superficial velocities and particle sizes.

Gravity-based pre-concentration strategies for complex rare earth ore containing niobium and zirconium

The Balzhe rare earth mine, renowned for its rich reservoirs of niobium, zirconium, and rare earth elements, poses a unique challenge due to its diverse and interbedded mineral composition. Despite the abundance of these elements, their valuable grade remains notably low, falling short of economic thresholds. To this end, pre-concentration of valuable minerals to discard gangue minerals before flotation would be an economical option. In response, this study delves into the feasibility of gravity-induced pre-concentration, aiming to segregate valuable minerals from gangue for subsequent flotation processes. Conducting float-and-sink tests on varied particle sizes (-2+0.5 mm, -0.5+0.074 mm, and -0.074+0.02 mm) within heavy liquids of specific gravities (ranging from 2.55 to 2.85), the study reveals the effectiveness of gravity separation. Notably, particles sized -2+0.5 mm and -0.074+0.02 mm demonstrated superior separation performance over the -0.5+0.074 mm fraction. Comparative analysis of diverse gravity separation equipment unveiled compelling results. The dense medium cyclone separator showcased impressive recovery rates and high-grade concentrates of Nb&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt;, ZrO&lt;sub&gt;2&lt;/sub&gt;, and total rare earth oxides (TREO) at 0.34%, 8.20%, and 0.41%, respectively, surpassing the sand table's performance for -2+0.5 mm particles. Conversely, for -0.5+0.074 mm particles, the shaking table exhibited optimal separation efficiency, yielding grades of Nb&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt;, ZrO&lt;sub&gt;2&lt;/sub&gt;, and TREO at 0.37%, 4.08%, and 0.44%, with substantial recovery values. Ultimately, the Knelson centrifugal separator proved most effective for -0.074+0.02 mm particles, yielding notable grades and recoveries of Nb&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt;, ZrO&lt;sub&gt;2&lt;/sub&gt;, and TREO. This study underscores the promising potential of gravity-induced pre-concentration techniques for enhancing the recovery of valuable elements from the complex Balzhe rare earth ore, offering critical insights into optimizing mineral extraction processes.

Hydrothermal Synthesis of CuO Nanoparticles: Tailoring Morphology and Particle Size Variations for Enhanced Properties

Transition metal oxides, particularly copper oxides, have garnered significant attention due to their intriguing photochemical, photomagnetic, photo-thermal, and photoconductive properties. Among these, CuO stands out as a p-type semiconductor having narrow bandgap energy ranges from 1.2 to 2 eV, finding versatile applications such as gas sensing, magnetic storage, solar energy conversion, photocatalysis, supercapacitors, field-emission emitters, and optical switches. Additionally, it serves as a crucial component in materials designed for lithium-ion electrodes. In this study, five different CuO nanoparticles were synthesized by simple and cost-effective hydrothermal method with various reaction temperatures and times in a teflon lined stainless steel autoclave. Copper (II) chloride dihydrate was used as copper source in this process. Various characterization techniques were conducted including X-ray powder diffraction (XRD), Raman spectroscopy, and transmitting electron microscopy (TEM). The effect of temperature and time on synthesis process was characterized and discussed. TEM images show that particle size of CuO increase with the temperature and reaction time. First reaction had the smallest particle sizes (mostly around 9-11 nm). This can be attributed to its lowest reaction temperature and shortest reaction time. For the other reactions, two of them accumulate around 19-35 nm and two around 27-45 nm range. However, the rise in the particle’s diameters is not directly proportional to temperature and time. As a result, CuO nanoparticles have been produced with simple method for the market. It can be produced in large quantities for heat exchangers, gas sensing, magnetic storage, solar energy conversion, photocatalysts, supercapacitors, etc.

The Impact of ZIF-8 Particle Size Control on Low-Humidity Sensor Performance

An accurate humidity measurement is essential in various industries, including product stability, pharmaceutical and food preservation, environmental control, and precise humidity management in experiments and industrial processes. Crafting effective humidity sensors through precise material selection is crucial for detecting minute humidity levels across various fields, ultimately enhancing productivity and maintaining product quality. Metal–organic frameworks (MOFs), particularly zeolitic imidazolate frameworks (ZIFs), exhibit remarkable properties and offer a wide range of applications in catalysis, sensing, and gas storage due to their structural stability, which resembles zeolites. The previous research on MOF-based humidity sensors have primarily used electrical resistance-based methods. Recently, however, interest has shifted to capacitive-based sensors using MOFs due to the need for humidity sensors at low humidity and the resulting high sensitivity. Nevertheless, further studies are required to optimize particle structure and size. This study analyzes ZIF-8, a stable MOF synthesized in varying particle sizes, to evaluate its performance as a humidity sensor. The structural, chemical, and sensing properties of synthesized ZIF-8 particles ranging from 50 to 200 nanometers were examined through electron microscopy, spectroscopic, and electrochemical analyses. The fabricated copper electrodes combined with these particles demonstrated stable and linear humidity sensing capabilities within the range of 3% to 30% relative humidity (RH).

Spherical Graphite Anodes: Influence of Particle Size Distribution and Multilayer Structuring in Lithium-Ion Battery Cells

Current research focuses on lithium-ion battery cells with a high energy density and efficient fast-charging capabilities. However, transport limitations, and, therefore, the uniform diffusion of lithium-ions across the electrode layers, remain a challenge and could lead to reduced cell performance. One approach to overcome these transport challenges is the use of subsequently produced two-layer anodes with the particle size variation of spherical graphite (x50 = 18 µm; x50 = 11 µm). Thereby, a defined pore network is created, which reduces the ionic resistance and ensuring improved fast charging capabilities. The analysis focuses on the evaluation of electrode properties and the electrochemical performance. By examining the pore size distribution of the anodes, it has been found that during the manufacturing of the two-layer anodes, carbon black and binder particles are transported into the existing microstructure of the lower layer, resulting in localized densification between the anode layers. This could also be supported by color measurements. This effect also extends to electrochemical investigations, with electrochemical impedance spectroscopy showing significantly lower ionic resistances in all two-layer anodes. Reduced ionic resistance and tortuosity near the separator due to absorption effects enhance the ion diffusion and have a direct impact on anode performance. Cell ageing analysis showed a significant capacity decrease of almost 15 mAh g −1 in the single-layer references only, in contrast to the stability of the two-layer anodes. This could also be attributed to the reduced ionic resistance and active counteraction of binder migration. In conclusion, this study highlights how subsequently produced two-layer anodes significantly shape the electrode properties and cell performance of lithium-ion batteries.

The Utilization of Candlenut Shell-Based Activated Charcoal as the Electrode of Capacitive Deionization (CDI) for Seawater Desalination

Activated carbon or activated charcoal is one of the best materials that can be used as a constituent of CDI electrodes, not only because of its various advantageous properties but also because it can be sourced abundantly from plant waste. This research aims to determine the effect of the thickness of the candlenut shell activated charcoal electrode and the particle size of the activated carbon used on the capacitive deionization (CDI) performance in seawater desalination. Candlenut shell-based activated charcoal is obtained in three stages, namely preparation, carbonization, and activation. The carbonization stage was done by using a pyrolysis reactor at a temperature of 400°C for 8 hours. The activation was done with the activator of H3PO4 67%. The variation of thickness was 6 mm, 8 mm, 10 mm, and 15 mm while the variation of particle size was 60 mesh, 80 mesh, 100 mesh, and 200 mesh. The results showed that the higher capacitance was obtained with the thinner electrodes, where the best value was the thinnest electrode, 6 mm, which produced the highest capacitance, 122.96 nF. For the desalination of seawater, it is shown that the finest particle/smallest particle size will result in the best desalination performance, where 200 mesh particle size will result in the decrease of salinity from 34% to 4%. That is 88.23% decrease in salinity. Therefore, the using of candlenut shell-based activated carbon as the electrode in CDI is proven to be able to obtain good performance in seawater desalination.

The effects of silver particle size on bacterioplankton community and potential function in aquatic environment

Silver nanoparticles (AgNPs), known for their antimicrobial properties, are increasingly being recognized as a water pollutant, with their physicochemical properties varying based on particle size. However, there is a lack of research on whether presence of AgNPs and their particle size affect bacterial communities in water bodies. In this study, the water from Chaohu Lake was collected and spiked with AgNPS of different particle sizes of (5 nm, 50 nm, and 100 nm) to stimulate the microbial response. Our findings revealed that the presence of AgNPs could significantly disrupt bacterial community structure and strengthen the associations between certain bacteria, with significant impacts observed on nitrifying and denitrifying processes. Different particle sizes of AgNPs had various effects on bacterial community structure, with small-sized AgNPs affecting the bacterial community the most. Moreover, the presence of AgNPs and their varying particle sizes were observed to significantly affect the nitrogen cycle, carbon cycle, and respiration, thus imposing significant impacts on other ecological functions of aquatic ecosystems. This study provides a baseline study on the aquatic ecotoxicological effects of AgNPs.

Multi-response optimisation of EDM process machined by P/M electrodes made of micron and nano level particles

ABSTRACT In electric discharge machining (EDM), the use of customised powder metallurgy (P/M) electrodes is of tremendous importance. The particle size of the P/M electrode, compaction pressure, and elemental composition of tool electrodes significantly influences the machining efficiency of the EDM. However, particle size variations were hardly studied, importantly when the particle size is at ‘Nano level’. In the present investigation, machine tool and electrode parameters are considered for evaluating the machining efficiency by measuring the material removal rate (MRR) and tool wear rate (TWR). The workpiece and tool electrodes are D2 alloy steel and WC/Co P/M electrodes, respectively. Taguchi’s L18 orthogonal array was used in the design of experiments. The parameters Particle size (PS), Peak current (IP), Compaction Pressure (CP) and wt% of Co (%Co) have all been found to have a substantial impact on improving MRR and TWR simultaneously. At the optimal combination of parameters, MRR was improved from 109.1 to 151.9 mg/min, and TWR was lowered from 7.1 to 5.9 mg/min with the proposed method. Predicted results are compared with confirmation experiments to validate the findings. The probable reasons that contributed to the enhancement of performance measures are discussed.

Numerical modelling of ventilation strategies for mitigating cough particles transmission and infection risk in hospital isolation rooms

This study used numerical modelling to analyze air velocity, cough particle distribution and infection risks in an isolation room. It investigated air change rates, inlet/outlet vent positioning and assessed various ventilation rates and outlet configurations for reducing infection risks. Quantitative assessments revealed different particle escape timings. In Case 1, smaller particles (2–4 μm) took 8.2 s to escape, while in Case 2, this time extended to 22.7 s. At 48 ACH, there were significant improvements in removing particles of various sizes, particularly those sized 2–4 μm, 16–24 μm and 40–50 μm, reducing the infection risk. The use of the Wells-Riley model highlighted considerable reductions in infection probabilities with higher ACH. Specifically, infection risks were reduced to 5% in Case 1 and 17% in Case 2, underscoring the marked advantage of Case 1 in reducing infection probabilities, particularly for smaller particles. Furthermore, escalated ACH values consistently correlated with decreased infection probabilities across all particle sizes, highlighting the pivotal role of ventilation rates in mitigating infection risks. The study comprehensively investigated the distribution of air velocity, dynamics of cough particles and infection risk associated with different ventilation strategies in isolation rooms.