Fine Particles Research Articles

Effect of high-frequency ultrasonication on degradation of polytetrafluoroethylene (PTFE) microplastics/nanoplastics

Polytetrafluoroethylene (PTFE) particle might present a significant contamination in environment due to its dual classification as a microplastic and a fluorinated compound (a type of PFAS, or per- and polyfluoroalkyl substances), coupled with its extreme stability. Identifying an effective degradation method for PTFE microplastics is thus crucial towards remediation, along with the suitable monitoring approaches. This study is the first to use high-frequency (580 kHz) ultrasonication for the degradation of the PTFE microplastics with diameter of ∼1000 nm. Dispersion of PTFE microplastics with help of surfactant (SDS, or sodium dodecyl sulfate) followed by ultrasonication for 9 h under optimal conditions resulted in a defluorination percentage of ∼32 %. Particle size analysis demonstrated the effective diameter shrink of PTFE microplastics by ultrasonication (from ∼1000 nm to ∼330 nm that can be categorized as nanoplastics). SEM-EDS provided clear visualization of PTFE microplastics/nanoplastics, while Raman imaging confirmed the fine particles from molecular spectrum window. ImageJ analysis algorithms were utilized to estimate particle sizes as well. Based on these findings, a potential degradation mechanism for PTFE microplastics/nanoplastics was proposed. This study contributes to the understanding of PTFE degradation and may facilitate further research in this field.

Enhanced performance of cyclone separator through coupling of centrifugal force, electrostatic force and particle pre-charge

The electrostatic enhancement can effectively improve the performance of cyclone separator at low load or high-temperature, but its application is limited owing to the reduction of spark voltage in high-temperature. Aiming at this question, a new technology coupling centrifugal force, electrostatic force and particle pre-charge was proposed. The characteristics of particles charging and agglomeration were analyzed, and the influence of different factors on the change of particle partition number concentration and total removal efficiency of cyclone separator were studied. The results showed that, increasing the charge generator voltage and decreasing the main pipe gas velocity can increase the particles charge quantity and improve agglomeration, which is benefit for the efficiency improvement of either cyclone separator or electrostatic cyclone separator, especially at low inlet gas velocity. Higher charge generator voltage and lower inlet gas velocity, more obvious efficiency improvement. The total removal efficiency can be increased by up to 10 % and 9 % respectively for the cyclone separator and electrostatic cyclone separator because of particle pre-charge at 10 m/s of inlet gas velocity, and the removal efficiency of fine particles can also be effectively improved. Comparing with the electrostatic cyclone separator, achieving the same total removal efficiency, the internal voltage can be reduced 16 kV through particle pre-charge. The electrostatic force and centrifugal force were the main factor of the small particles and big particles removal, respectively.

DEVELOPMENT OF ADVANCED COMPOSITIONS INCORPORATING WOLLASTONITE, THERMOVERMICULITE, SILICON IV OXIDE, AND AEROSIL

This study presents the development of innovative composite materials by incorporating wollastonite, thermovermiculite, silicon IV oxide (SiO₂), and aerosil. The primary objective was to formulate high-performance materials with enhanced mechanical, thermal, and structural properties suitable for industrial and construction applications. Wollastonite and thermovermiculite, known for their excellent reinforcing properties, were combined with SiO₂ and aerosil to create a hybrid matrix. The materials were synthesized and characterized using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). Experimental results revealed that the new compositions exhibited superior heat resistance, improved strength, and enhanced durability compared to traditional materials. The inclusion of aerosil, with its fine particle size and high surface area, contributed to improved dispersion and homogeneity within the matrix, resulting in enhanced thermal stability and mechanical performance. These advanced composites hold great potential for applications in areas requiring robust thermal and structural integrity, including insulation, construction materials, and high-temperature industrial components. Future work will focus on further optimizing these formulations and exploring their use in specialized engineering fields.

Synthesis and Properties of CaMgSi2O6 - SrO Bioceramics for Enhanced Hydroxyapatite Formation and Cell Viability in Bone Regeneration

This study aims to synthesize and evaluate the properties of diopside (CaMgSi2O6) and strontium modified diopside (CaMgSi2O6-SrO) bioceramics for potential bone regeneration applications. The substitution of strontium for calcium leads to the formation of solid solutions: Sr-CaMgSi2O6, Ca-SrMgSi2O6, and a single phase of SrMgSi2O6, along with secondary phases of Ca-Sr2MgSi2O7 and Sr2MgSi2O7. This study is the first to examine the physical and biological properties of SrMgSi2O6 and its solid solutions. Microstructural analysis reveals that the pure diopside exhibits uniformly packed fine particles, while the SrO substitution results in lattice distortion and structural damage, thus weakening the mechanical properties and biodegradation resistance. The in vitro hydroxyapatite (HAp) formation ability of CaMgSi2O6-SrO bioceramics is comprehensively investigated, revealing that the re-adsorption of Mg2+/Sr2+ is a crucial factor. Pure diopside and Sr0.25 demonstrate effective HAp formation after immersion in simulated body fluid (SBF), with Sr0.25 showing finer particles and more uniform distribution due to appropriate Sr2+ re-adsorption. In contrast, SrO-rich samples show reduced HAp formation due to excessive re-adsorption of Mg2+ and Sr2+ ions, hindering HAp nuclei development. The cell viability test reveals that SrO substitution enhances cell viability due to increased surface area and the release of beneficial ions. Overall, Sr0.25 demonstrates excellent potential for bone regeneration applications by promoting HAp uniformity.

Reconstructing the past environmental conditions of southwestern India using estuarine sediment core

Geological archives can be examined via multiple proxies to uncover significant information about historical environmental changes. In comparison to single proxy approach, the use of multiple proxies can provide better resolution of the paleoenvironmental record. Thus, in the present study, to understand the paleoenvironmental conditions in the Kali coast in southwestern India, sedimentological, geochemical and isotopic (210Pb, 137Cs) proxies were used. The findings demonstrated that, in previous decades, the sedimentation rate varied from 0.5 to 1.0 cm/year under conditions with relatively higher hydrodynamic energy that were more common and fluctuating, allowing for larger sand particle deposition. However, in more recent years, finer particle deposition towards the surface has been observed under conditions with lower and more stable hydrodynamic energy, with a sedimentation rate of 1.87 cm/year. Additionally, the finer fractions displayed a strong correlation with the metal distribution, which was mostly governed by Fe-Mn oxides. Furthermore, it can be revealed that the environment was warm, humid, and marine-like between 1995 and 2000 based on chemical weathering intensity values and Rb/K ratios. A subtle shift to a freshwater habitat with relatively less warm, less humid climate occurred between 2000 and 2020. Therefore, similar research with longer depositional histories coupled with multiple proxies can help predict the future climatic shifts in decadal time scales.

An eco-friendly approach for graphene nanoplatelets by innovative wet thermal expansion and liquid-phase exfoliation

Cost-effective synthesis of high-structural integrity graphene nanoplatelets (GNPs) remains a grand challenge. This study presents an innovative, environmentally friendly and efficient method for synthesizing high-quality GNPs by integrating wet thermal expansion with liquid-phase exfoliation. The thermal expansion of a wet graphite intercalation compound (GIC) in a semi-closed system improves the expansion effectiveness, minimizes the release of fine dust and improves the hydrophilicity of the resulting product. These improvements significantly enhance the effectiveness and efficiency of the subsequent liquid-phase exfoliation by shearing, which produces GNPs in pure water within 30 min with an overall productivity of 38.24 %. GNPs exhibit desirable properties, e.g. few layers (1–2 nm thick), large lateral dimension (a few microns), high sp2 hybridized carbon content (86 %), rich surface functional groups yet a low oxidation level (C/O ratio = 21.7 and electrical conductivity of ∼ 2055 S cm−1). The simplicity, adjustability and scalability of this method, combined with environmental friendliness, make it highly suitable for various applications and pave the way for further advancements in sustainable nanotechnology practices.

Primary Study on Influence of Conventional Hydrochemical Components on Suspension of Endogenous Fine Loess Particles in Groundwater over Loess Regions

To ascertain the effects of conventional hydrochemical components on the presence of endogenous fine loess particles (EFLPs) in groundwater over loess regions, Na+, NO3− and Cu2+, as conventional hydrochemical components, were employed in batch tests with EFLPs from a typical loess as aquifer media in Guanzhong Plain, China. The results showed that EFLPs had high zeta potential (ζ) and remained suspended over 40 h, indicating their good dispersity and potential to be suspended in groundwater. ζ was employed to replace electrostatic repulsion in the DLVO equation to determine the critical coagulation concentrations for Cu(NO3)2 and NaF as 0.1 mmol/L and 50 mmol/L for 1.1 µm D50 EFLPs, which were almost consistent with the batch test results and greater than those in the groundwater, respectively, further implying that EFLPs are likely to be suspended in groundwater. The multi-factor tests showed that the key factors including particle size, hydro-chemical component and concentration interacted with each other and their relative magnitudes varied in the test processes, where the effects of concentration strengthened while those of the component weakened. So, hydrogeochemical conditions were beneficial to the suspension of EFLPs and the benefit got strong along the groundwater flow path, which is conducive to the cotransport of EFLPs with pollutants in groundwater over loess regions.

Partial replacement of sand by fine-grained crushed waste glass along with fly ash stabilization for geotechnical applications in pavement

Natural sand (NS) is one of the most used engineering materials in almost all types of construction worldwide. Considering environmental sustainability, the replacement of natural sand with crushed glass waste (CWG) can provide a solution for both geo-environmental problems of natural sand depletion and waste glass disposal at a time, since sand and glass share almost similar chemical components. This research aimed to investigate the mechanical behaviors of natural sand replaced with fine CWG particles by 5 %, 10 %, 15 %, 20 %, 25 %, 30 %, and 35 % of dry weight. NS-CWG optimum composition was then stabilized by adding Class C fly ash (FA) from 5 to 35 % of NS-CWG to find out the optimum FA content to stabilize NS-CWG. The effects were analyzed through compaction, direct shear, and California Bearing Ratio (CBR) tests. Test results showed that maximum dry density increased, and optimum moisture content decreased due to adding CWG, and a contrasting effect was found after adding FA. 25 % FA significantly stabilized the NS-CWG mixture's strength parameters, such as increased cohesion, angle of internal friction, improved shear strength by 55.67 %, and increased CBR by 44 %. The decreased roundness index and scanning electronic microscopy (SEM) test results further evaluated and supported the improved geotechnical properties of NS + CWG + FA. The findings of the study can be useful in producing recycled materials for constructing road pavements of sustainable transport network development.

Fine particles composition and emission chemical profiles from sugarcane production for source reconciliation applying the Chemical Mass Balance

Abstract. Every year, many tons of fine particles are emitted to the atmosphere due to the sugarcane-mills operation and for inadequate agricultural practices such as sugarcane burning. In order to foster a deeper knowledge about the levels and source contributions of particles and their toxic species, the City of Cordoba was selected for two PM2.5 sampling campaigns to be carried out in the center and in a rural location at 9 km far, during harvesting and non-harvesting seasons; additionally, the chemical source profiles from sugarcane burning and sugar mills were determined. The PM2.5 levels in the City of Córdoba ranged from 29.9 to 102.1 mg m-3 and from 13 to 36.6 mg m-3 in the harvest and non-harvest periods, respectively, but toxic chemical species rose up to nine times representing an important risk health. Total carbon concentrations during harvesting were around 67 % and 64 %. With the chemical source profiles and the PM2.5 airborne concentrations, the Chemical Mass Balance Model was applied for source reconciliation, evincing that sugarcane processes accounted with 22 % of fine particles, vehicles with 34 to 38 %, secondary inorganic aerosols from 16 to 24 %, and suspended particles from roads from 10 to 20 %. The results show that inhabitants in this area are exposed to high levels of PM2.5 in harvesting, with a high risk to their health. This study provides valuable information to the authorities for the PM2.5 control strategies design and protect the population health, during harvesting. Resumen. Cada año, se emiten muchas toneladas de partículas finas a la atmósfera debido a la operación de los ingenios azucareros y a prácticas agrícolas inadecuadas como la quema de caña de azúcar. Con el fin de fomentar un conocimiento más profundo sobre los niveles y las contribuciones de origen de las partículas y sus especies tóxicas, la ciudad de Córdoba fue seleccionada para llevar a cabo dos campañas de muestreo de PM2.5 en el centro y en una ubicación rural a 9 km de distancia, durante las temporadas de cosecha y no cosecha; además, se determinaron los perfiles químicos de la quema de caña de azúcar e de los ingenios. Los niveles de PM2.5 en la ciudad de Córdoba oscilaron entre 29.9 y 102.1 μg m-3 y entre 13 y 36.6 μg m-3 en los períodos de cosecha y no cosecha, respectivamente, pero las especies químicas tóxicas se incrementaron hasta nueve veces, lo que representa un importante riesgo a la salud. Las concentraciones totales de carbono durante la cosecha fueron aproximadamente del 67 % y el 64 %. Con los perfiles químicos de origen y las concentraciones de PM2.5 en el aire, se aplicó el Modelo de Balance de Masas Químicas para la reconciliación de fuentes, demostrando que los procesos de caña de azúcar representaban el 22 % de las partículas finas, los vehículos el 34 al 38 %, los aerosoles secundarios del 16 al 24 %, y las partículas suspendidas de las carreteras del 10 al 20 %. Los resultados muestran que los habitantes de esta zona están expuestos a niveles altos de PM2.5 durante la cosecha, con un alto riesgo para su salud. Este estudio proporciona información valiosa a las autoridades para el diseño de estrategias de control de PM2.5 y proteger la salud de la población, durante la cosecha.

Compaction Characteristics of Fly Ash and Pond Ash: A Comparative Analysis

This study investigates the compaction characteristics of Fly Ash and Pond Ash, which are by-products of coal combustion in thermal power plants. Thermal power plants generate three types of ash: (a) Fly Ash, (b) Pond Ash, and (c) Bottom Ash. Fly Ash consists of fine particles carried out of the boiler with flue gases, while Bottom Ash is the residue that settles at the bottom of the boiler. In most coal plants, Fly Ash is captured using electrostatic precipitators and other filtration equipment before the flue gases are released through the chimney. Pond Ash, on the other hand, is a by-product of thermoelectric power plants, often regarded as waste material, posing significant environmental disposal challenges. The compaction characteristics of Fly Ash and Pond Ash are influenced by various factors, including specific gravity, moisture content, compaction energy, layer thickness, and mold area. In this study, Fly Ash collected from NTPC Sipat , Chhattisgarh exhibited an Optimum Moisture Content (OMC) ranging from 18% to 27% and a Maximum Dry Density (MDD) ranging from 0.90 to 1.59 gm/cc under standard Proctor compaction energy. Similarly, Pond Ash demonstrated an OMC ranging from 33% to 46% and an MDD ranging from 0.856 to 1.248 gm/cc under the same conditions. The findings indicate that variations in these factors significantly affect the dry density of both Fly Ash and Pond Ash. The study also aims to determine the geotechnical properties of these materials, providing insights into their potential applications in engineering and environmental management

Evaluation and Determination of the Physical Properties of Gasoline and the Presence of Fine Particles in the Ten Districts of the City of N'djamena

The context, which allowed to write this article is the fact that we have noticed an increase in the environmental impact caused by the poor management of car parks and fuel sellers as well as the proliferation of service stations that do not respect any standards. The illegal storage and marketing of petroleum products, especially gasoline, in the city of N'Djamena is the main factor of vulnerability and criticality of air pollutants, thus demonstrating the growing environmental impact in the city of N'Djamena. The presence of Polycyclic Aromatic Hydrocarbons (PAHs) as well as that of fine particles which are part of the Persistent Organic Pollutants (POPs) and characterize by their toxicities, their persistence in the environment, their bioaccumulation in living tissues, and their long-distance transport. Thus, the main objective of this work is to determine and evaluate the physical properties of gasoline and the presence of fine particles in the ten districts of the city of N'Djamena. These are the species sold on the street and presenting a danger to users. The main idea would be to look for gas stations and points of sale that comply with the regulations in force and those that do not. Then physical analyses were carried out on different types of gasoline consumed and then the air quality was measured with a Purple Air sensor. In conclusion, a complete structure of the ten districts with their degrees of pollution as well as the number of gas stations and fuel sellers on the street will be listed.

Annual Variations of PM10, PM2.5 and PM1.0 Fraction at an Urban Site in Ansan, Korea

This study examines particulate matter (PM) concentrations, specifically PM10, PM2.5, and PM1.0, at an urban site in Ansan, South Korea. Three BAM-1020 continuous monitors measured PM10, PM2.5, and PM1.0 hourly from January to December 2021, with data acquisition rates of 97.1%, 97.3%, and 93.4%, respectively. Average annual concentrations were 45.7±48.4 µg/m³ (PM10), 26.4±22.7 µg/m³ (PM2.5), and 18.5±14.5 µg/m³ (PM1.0). PM10 was 91% of the annual air quality standard, while PM2.5 exceeded this standard by 176%, indicating severe pollution. Statistical analyses using probability density function (PDF) and cumulative distribution function (CDF) showed 98.5% of data converged at 150 µg/m³ (PM10), 75 µg/m³ (PM2.5), and 50 µg/m³ (PM1.0), with the remaining 1.5% corresponding to approximately 131 hours, annually. In 2021, all six observed yellow dust events occurred in spring (March to May). PM10, PM2.5, and PM1.0 concentrations increased from January to March, peaked in March, decreased until September, and rose again. The coarse fraction ratio increased stepwise from February to May, likely due to yellow dust and episodes of high PM concentration in the spring. The PM1.0 concentration was higher in summer and fall compared with that in spring and winter. The PM1.0/PM2.5 ratio was highest in summer and fall even though the annual PM1.0concentration was lowest, suggesting a higher secondary formation rate of fine particles during these periods. This underscores the need for further scientific investigation on PM1.0. The study provides insights into the simultaneous observation and distribution characteristics of PM10, PM2.5, and PM1.0, highlighting the mass concentration, distribution, and ratio of PM1.0. These findings are crucial for understanding PM distribution in Ansan, an industrial complex, and can serve as essential data for chemical composition comparisons, data validation, public health strategies, and cost-benefit analyses for regional PM improvement.

Inhaled corticosteroid delivery is markedly affected by breathing pattern and valved holding chamber model.

There is a scarcity of high-quality research on the efficient delivery of inhaled corticosteroids using valved holding chambers (VHCs) in children. The delivered dose (DD) of fluticasone from a metered dose inhaler (pMDI) was tested using four VHCs: AeroChamber plus Flow-Vu (AC), Babyhaler (BH), EasyChamber (EC), and Optichamber Diamond (OD). The in vitro setup included an anatomical child throat model, Next Generation Impactor, and a breathing simulator to generate tidal breathing of a four and a 6-year-old child, and adult type single inhalation. OD showed the lowest proportion of fluticasone trapped in the throat with all breathing patterns. AC showed similar fine particle dose (FPD) in the respirable range (1-5 µm) irrespective of the breathing pattern. For BH, the median FPD 1-5 µm was highest during adult breathing. OD and EC showed higher overall DD and higher doses in the 1-5 µm range with paediatric breathing profiles compared to adult inhalation. The median DD and FPD 1-5 µm were significantly lower with BH compared to any other VHCs during tidal breathing. Compared to EC, the FPD of the other VHCs were skewed towards <2 µm particles. Fluticasone delivery is markedly affected by breathing pattern and VHC model. The observed differences in throat deposition and FPD delivered may have significant clinical implications for side effects and controlling airway inflammation. All VHCs intended for paediatric use should undergo testing using internationally recognised standardised methods incorporating clinically relevant paediatric breathing patterns.

On the dose-response association of fine and ultrafine particles in an urban atmosphere: toxicological outcomes on bronchial cells at realistic doses of exposure at the Air Liquid Interface

Air pollution and particulate matter (PM) are the leading environmental cause of death worldwide. Exposure limits have lowered to increase the protection of human health; accordingly, it becomes increasingly important to understand the toxicological mechanisms on cellular models at low airborne PM concentrations which are relevant for actual human exposure. The use of air liquid interface (ALI) models, which mimic the interaction between airborne pollutants and lung epithelia, is also gaining importance in inhalation toxicological studies. This study reports the effects of ALI direct exposure of bronchial epithelial cells BEAS-2B to ambient PM1 (i.e. particles with aerodynamic diameter lower than 1 μm). Gene expression (HMOX, Cxcl-8, ATM, Gadd45-a and NQO1), interleukin (IL)-8 release, and DNA damage (Comet assay) were evaluated after 24 h of exposure. We report the dose-response curves of the selected toxicological outcomes, together with the concentration-response association and we show that the two curves differ for specific responses highlighting that concentration-response association may be not relevant for understanding toxicological outcomes. Noteworthy, we show that pro-oxidant effects may be driven by the deposition of freshly emitted particles, regardless of the airborne PM1 mass concentration. Furthermore, we show that reference airborne PM1 metrics, namely airborne mass concentration, may not always reflect the toxicological process triggered by the aerosol.These findings underscore the importance of considering different aerosol metrics to assess the toxicological potency of fine and ultrafine particles. To better protect human health additional metrics should be defined, than account for the properties of the entire aerosol mixture including specific as particle size (i.e. particles with aerodynamic diameter lower than 20 nm), the relevant aerosol sources (e.g., traffic combustion, secondary organic aerosol …) as well as their atmospheric processing (freshly emitted vs aged ones).

Comparative performance study of paperboard disposable spacers versus commercial valved holding chambers for aerosol delivery

PurposeThe aim of this study is to evaluate and compare the performance, for the administration of fluticasone propionate with a pressurized metered-dose inhaler (pMDI), of two low-tech paperboard spacers versus two commercially available valved holding chambers (VHC). MethodsAccording to the Canadian standard CAN/CSA-Z264.1–02, total emitted dose (TED) and aerodynamic size distribution were measured for the pMDI in combination with 4 different spacers: a homemade paper cup spacer, the DispozABLE® paperboard spacer, the AeroChamber Plus® plastic VHC, and the Vortex® aluminium VHC. ResultsThe two disposable paperboard spacers had a lower TED compared to the aluminium VHC, but delivered more than 2.5 times the dose of fluticasone than the commercial plastic VHC. The 3 antistatic devices (i.e. the aluminium VHC, the paperboard DispozABLE® spacer and the paper cup spacer) delivered a significantly higher dose of fine particles than the less antistatic plastic VHC. Their fine particle fraction was statistically similar to that obtained with pMDI without spacer. This respirable fraction ensures an optimal therapeutic effect. All spacers limited the flow of coarse particles, thus avoiding adverse effects on the trachea and oropharynx. ConclusionWe have shown that inexpensive and low-tech paperboard spacers are interesting alternatives for the administration of aerosols.

A new framework for assessing carbon fluxes in alpine rivers

Riverine carbon dynamics connecting land and ocean carbon cycles play a crucial role in regulating global carbon turnover. Despite its importance, the impact of climate change and runoff components on riverine carbon dynamics, particularly in alpine regions, remains underexplored. In this study, we introduce a conceptual framework to assess the impact of climate change on riverine carbon fluxes across various runoff components. We use a distributed hydrological model and stable isotopes to identify key runoff components, then identify the dominant drivers of variability in runoff carbon concentrations. We establish component-specific relationships between carbon concentrations and dominant drivers, assessing the watershed carbon balance through a comparative analysis of carbon fluxes in various runoff components. The proposed framework was validated in a representative watershed on the Qinghai-Tibet Plateau, and it effectively captured the seasonal carbon dynamics and the impact of climate change and runoff components. Our results indicated that runoff and temperature dominate riverine carbon concentrations. The carbon fluxes associated with rainfall and groundwater showed higher sensitivity to runoff, while those in the snowmelt component were more sensitive to temperature. We found seasonal variability in carbon fluxes, with particulate organic carbon concentrations peaking at 4.80 mgC/L during the thawing period and other carbon components (i.e., dissolved organic carbon, dissolved inorganic carbon, particulate inorganic carbon) peaking during the freezing period. We quantified the total carbon input and output for the watershed as 15.12 tC/km2/yr and 12.19 tC/km2/yr, with 51.2% of the carbon influx attributed to rainfall, 10.9% to groundwater, and 37.9% to snowmelt. Our study enhances the understanding of riverine carbon dynamics and offers a promising approach for predicting carbon budgets under climate change.

Effects of powderization of a granular diet on growth performance of the edible cricket, Teleogryllus occipitalis (Orthoptera: Gryllidae)

Abstract Farming edible crickets has environmental and nutritional benefits, as well as social benefits such as livelihood diversification. Commercial feeds for poultry and fish farming are often used to feed crickets, and in recent years, crop and food-processing by-products have also been used to improve sustainability. However, the design of feed for crickets has not been standardized. Here, we investigated growth and development of the Asian field cricket, Teleogryllus occipitalis (Audinet-Serville) (Orthoptera: Gryllidae), fed on different forms of the same diet. Body mass and the rate of development were significantly greater in crickets fed on millimetre-order granules than in crickets fed on micrometre-order powder. In addition, analysis of feeding behaviour revealed that crickets fed less frequently on the powdered diet than on the granulated diet. These results suggest that crickets have an avoidance behaviour towards fine particles, or that the granular form is easier for them to grasp and ingest than the powdery form, which may have contributed to growth performance. Simply feeding millimetre-order granules may contribute to the development of feed design for farming edible crickets.

Investigating sediment dynamics on a continental shelf mud patch under the influence of a macrotidal estuary: A numerical modeling analysis

Shelf mud patches represent major sinks for fine-grained particles on continental shelves, as well as for carbon and contaminants of continental origin. The West Gironde Mud Patch (WGMP) is an interesting example of such offshore marine systems as it is an active mud deposition area located offshore the Gironde estuarine mouth (France) at depths between 30 and 70 m. It is known to be the trap of fine particles coming from the estuary, but the contribution of this material to the total mass of the depocenter is poorly quantified. In addition, despite the economic and ecological issues at stake, the response of such subtidal sedimentary structure to the combination of tidal currents, waves, and river supply remain poorly understood. Thus, using a realistic 3-D hydrodynamic and mixed (mud/sand) sediment transport model, this study aims at investigating the sediment dynamics of the WGMP under different hydrometeorological conditions. The analysis of the residual fluxes at the estuarine mouth exhibited large discrepancies between the different sediment classes as well as for contrasted hydro-and meteorological conditions induced by different dominant transport mechanisms. During winter, the reinforced density gradients drive strong up-estuary baroclinic circulation at the bottom that dominates the sediment dynamics over the barotropic export of mud particles. The model also reproduced the signature of a subtidal mud accumulation area over the continental shelf around 30–40 m water depth, on the proximal side of the observed WGMP. On average over two years, 26% of the mud mass accumulating on the simulated subtidal mudflat comes from the estuary. The trapping efficiency of this mud patch is negatively correlated with the significant wave height. Moreover, due to the estuarine turbid plume being more concentrated and developed at the surface during high river discharge, the trapping efficiency of the mud body is enhanced compared to lower discharge. This study highlights the sensitivity of mud and sand fluxes to vertical and horizontal residual circulation, and points out the uncertainties associated with the simulation of short-term (i.e., years) fine particle deposits compared to long-term (i.e., centuries) sediment accumulation trends. In addition, these results show the primordial effects of both wave action and riverine sediment supply on the dynamics of such subtidal muddy structures, which raises concern about their fate facing climate change and human activities in the future.

Effect of Torrefaction Process on the Physicochemical Properties of Solid Fuel from Palm Kernel Shells

This research investigates the effects of torrefaction on the characteristics of solid fuel made from palm kernel seed (PKS). The torrefaction process was conducted on raw PKS to improve its energy density and combustion efficiency. Torrefaction was carried out at 400°C at different durations (30, 40, and 50 minutes), with the goal of improving the energy density and combustion efficiency of raw PKS. The torrefied PKS was then ground and sieved into particle sizes of 150mm and 300mm. After being blended with high-density polyethylene (HDPE), the torrefied PKS was compacted using hot press machine into solid fuel and tested for its physicochemical properties. The results indicated that PKS torrefied for 50 minutes with particle size of 300 mm exhibited optimal characteristics, with a high heating value (HHV) of 23.22 MJ/kg. The particle size plays a role, with finer particles (150mm) having lower HHV values compared to coarser particles (300mm). Additionally, the inclusion of HDPE affected the properties of the solid fuel. Morphological analysis using scanning electron microscopy provided insights into its structural features.

Impact of the feed particle size distribution and its packing characteristics on compression comminution

Due to its lower energy consumption than a conventional grinding circuit, there is an increased interest in the mining industry in the High-Pressure Grinding Rolls (HPGR) technology. Despite the benefits, the high quantity of material required to size the HPGR makes it difficult for new mines to consider this technology. The piston press test has been used at The University of British Columbia to predict the behavior of the HPGR. It is possible to predict energy requirements, size reduction, and throughput by utilizing a small amount of material to size the HPGR. The bulk material’s particle size distribution (PSD) plays an important role in how the particle bed will pack. This study investigates the differences in compressing three different sample PSDs obtained from the same copper ore crushed to −12.5 mm. The first PSD corresponds to the natural distribution resulting from the crusher. The second is created artificially to match the Fuller curve PSD, which theoretically should have the highest packing density. The third corresponds to a truncated feed produced by removing the fines (−300μm) from the natural feed. Tests were performed using a piston-and-die press test apparatus to compress the samples at different force levels. Entirely different behaviors are obtained while compressing the same material with different PSDs. Particularly, the Fuller curve PSD achieves a 31%–40% higher grinding rate than the natural feed, while the truncated feed achieves a 9%–30% higher grinding rate than the natural feed. Differences in the specific energy consumption, grinding efficiency, and final compacted densities highlight the critical influence of feed particle size distribution on the energy usage and generation of fine particles, underscoring the importance of optimizing these parameters for energy-efficient mineral processing. The overall findings indicate that an HPGR feed particle size distribution that matches the Fuller curve and, therefore, has a maximum packing density, results in the most energy-efficient comminution.