Particle Elemental Composition Research Articles

Assessment of the Mechanical and Microstructural Performance of Waste Kraft Fibre Reinforced Cement Composite Incorporating Sustainable Eco-Friendly Additives

This study investigates the influence of limestone powder and metakaolin as sustainable eco-friendly additives on the properties and behavior of cementitious composite boards, with a focus on mechanical strength, physical properties, and microstructural characteristics. The experimental investigation begins with the characterization of the raw materials, including limestone powder, and metakaolin, to assess their particle sizes, elemental composition, and microstructural features. Cement composite boards were fabricated using an innovatively developed lab-simulated vacuum dewatering process, by varying the proportions of limestone powder and metakaolin as partial replacements for cement, along with waste kraft fibres as reinforcement. Mechanical testing was conducted to evaluate the flexural strength and behaviour of the composite boards according to standardized procedures. A microstructural analysis was performed using scanning electron microscopy (SEM) to examine the effect of additives on the cementitious matrix, fibrematrix interaction, and hydration products. The findings from the experimental study reveal insights into the influence of limestone powder and metakaolin on the mechanical properties and microstructure of waste kraft fibre-reinforced cement composite boards. Our analysis of the results shows that adding 9% limestone powder as partial cement replacement produces a 24% and 50% enhancement in flexural strength at 7 and 28 days of hydration, while that of metakaolin as partial cement replacement was optimum at 6% with an enhancement of 4% and 36%, respectively, at 7 and 28 days of hydration. The implications of these findings for the development of sustainable cementitious composite are discussed, including the potential benefits of using limestone powder and metakaolin as supplementary cementitious materials in waste kraft fibre-reinforced cement composite boards. Finally, recommendations for optimizing additive proportions are also provided to enhance the understanding and application of these materials in the construction and building industries.

Fabrication of ZnO-quantum dot hybrid nanocomposites with enhanced light scattering and emission characteristics for micro LED display applications

Herein, a facile method is reported to fabricate a color conversion layer comprised of zinc oxide nanoparticles (ZnO NPs) and quantum dots (QDs) for micro-light emitting diode (μ-LED) displays. Further, 11-mercaptoundecanoic acid (MUA)-treated ZnO NPs (ZnO@MUA NPs) are synthesized via a high-energy ball milling method, which bypasses the need for complex synthesis processes and enables functional groups to attach to the surface, thereby facilitating the formation of ZnO@MUA NPs-QD hybrid composites (ZQCs). The particle size, surface characteristics, elemental composition, and binding energy are analyzed to elucidate the reaction mechanism and to confirm that the fabricated ZQC exhibits a chemically bonded structure. To ascertain the optimal molar concentration for incorporating the QDs, parameters such as QD bonding efficiency, quantity of bonded QDs, interparticle distance, and absolute photoluminescence quantum yield (PLQY) are evaluated as functions of molar concentration. As a result, the optimal molar concentration is found to be 1930 nM, giving a bonding efficiency of 96.8 %, along with the bonded QDs of 1.51 × 1011 per a unit area of 1 mm2 of ZnO NPs and a PLQY of 64.8 %. Furthermore, comprehensive optical analyses are performed to assess the potential of the ZQC as a color conversion material for μ-LED displays, in comparison to the use of pristine QDs and silica NP-QD composites.

Novel Damsissa carbon quantum dots (DCQDs) to improve the protection efficiency of permanganate phosphate conversion coats (PPC) on steel

Carbon quantum dots (CQDs) are spherical zero dimensional nanoparticles, generally below 10 nm in size, which received increasing attention in diverse application fields owing to their important characteristics and advantages as good water solubility, potential of environmental protection and preparation from abundant and sustainable raw materials. In this work, Damsissa carbon quantum dots (DCQDs) were generated via hydrothermal reaction microwaves irradiation. The DCQDs material was characterized by FTIR, TEM, EDX, XRD, and XPS to confirm the morphological and functionality aspects as well as particle size distribution, elemental composition, crystallite structure, and elemental identification in terms of chemical state. The FTIR analysis referred to associated assignments of C-H, C=O, C=C, C-N, besides other groups. The TEM study confirmed a ranged homogenous particle distribution at 3-6 nm. The EDX and XPS results verified carbon, nitrogen and oxygen as the main elements in DCQDs. The protection efficiency performance of permanganate phosphate conversion coat (PPC) was investigated and monitored by using different concentrations of DCQDs in the coating bath utilizing the potentiodynamic polarization technique, besides electrochemical impedance spectroscopy. The results referred to 97.4% maximum protection efficiency for the coat in presence of 400 mg/L DCQDs. The impedance results showed that as the concentration of DCQDs increase, the capacity of the double layer (Cdl) decreases due to the adsorption ofDamsissa carbon dots on the steel surface. However, the potentiodynamic polarization results indicated that the presence of DCQDs in HCl solution could lead to the polarization of the cathodic and anodic curves to denote that these retard the cathodic and anodic reactions at the steel surface inhibiting the corrosion process. The coats synthesized in absence and in presence of diverse amounts of DCQDs were examined by the TEM, EDX, XPS, and XRD studies to elucidate the role of DCQDs in the improvement of the corrosion protection of the coat. The results indicated that the DCQDs molecules ofDamsissa were adsorbed at the steel surface to efficiently retard the dissolution of iron and decrease the Fe2+ ions concentration in the coating solution causing higher nucleation rate over the crystal growth and thus leading to the formation of a uniform protective film.

Prevalence of nano-sized coal mine dust in North and Central Appalachian coal mines – Insights from SEM-EDS imaging

The increasing prevalence of coal mine dust-related lung diseases in coal miners calls for urgent and meticulous scrutiny of airborne respirable coal mine dust (RCMD), specifically focusing on particles at the nano-level. This necessity is driven by expanding research, including the insights revealed in this paper, that establish the presence and significantly increased toxicity of nano-sized coal dust particles in contrast to their larger counterparts. This study presents an incontrovertible visual proof of these tiny particulates in samples collected from underground mines, utilizing advanced techniques such as scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The intricate elemental composition of nano-sized coal dust identified through EDS analysis reveals the presence of elements such as silica and iron, which are known to contribute to lung pathologies when inhaled over prolonged periods. The outcomes of the statistical analyses reveal significant relationships between particle size and elemental composition, highlighting that smaller particles tend to have higher carbon content, while larger particles exhibit increased concentrations of elements like silica and aluminum. These analyses underscore the complex interactions within nano-sized coal dust, providing critical insights into their behavior, transport, and health impacts. The nano-sized coal dust could invade the alveoli, carrying these toxic elements from where they are impossible to exhale. The revelation of nano-sized coal dust's existence and the associated health hazards necessitate their incorporation into the regulatory framework governing the coal mining industry. This study lays the groundwork for heightened protective measures for miners, urging the invention of state-of-the-art sampling instruments, comprehensive physicochemical profiling of RCMD nanoparticles, and the pursuit of groundbreaking remedies to neutralize their toxic impact. These findings advocate for a paradigm shift in how the coal mining industry views and handles particulate matter, proposing a re-evaluation of occupational health standards and a call to action for protecting coal miners worldwide.

Phytoplankton stoichiometry along the salinity gradient under limited nutrient and light supply.

Ongoing climate warming alters precipitation and water column stability, leading to salinity and nutrient supply changes in the euphotic zone of many coastal ecosystems and semi-enclosed seas. Changing salinity and nutrient conditions affect phytoplankton physiology by altering elemental ratios of carbon (C), nitrogen (N) and phosphorus (P). This study aimed to understand how salinity stress and resource acquisition affect phytoplankton stoichiometry. We incubated a phytoplankton polyculture composed of 10 species under different light, inorganic nutrient ratio and salinity levels. At the end of the incubation period, we measured particulate elemental composition (C, N and P), chlorophyll a and species abundances. The phytoplankton polyculture, dominated by Phaeodactylum tricornutum, accumulated more particulate organic carbon (POC) with increasing salinity. The low POC and low particulate C:N and C:P ratios toward 0psu suggest that the hypoosmotic conditions highly affected primary production. The relative abundance of different species varied with salinity, and some species grew faster under low nutrient supply. Still, the dominant diatom regulated the overall POC of the polyculture, following the classic concept of the foundation species.

Using of crushed glass supported Fe/Cu bimetallic nanoparticles for remediation of ciprofloxacin antibiotic from aqueous solution

The combination of iron and copper (Fe/Cu) loaded on glass (G-Fe/Cu) has been developed for this study. The green synthesis was used to create bimetallic nanoparticles (G-Fe/Cu) using grape leaves extract, which employed as a natural reducing agent to easily produce nZVI from iron salts. The particle size, surface morphology, elemental composition and degree of crystallinity of the resulting nanocomposite have been analyzed by means of energy-dispersive X-ray spectroscopy (EDX), scanning electronic microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). G-Fe/Cu nanocomposite were employed as adsorbent materials to eliminate ciprofloxacin (CIP) from polluted aqueous solution. Some factors affecting the adsorption function, in batch and continuous experimentations have been examined to select the optimum parameters that accomplish the maximum elimination ratio (99 %) and to investigate the efficiency of the nanoparticles as reactive bed materials. It was discovered that the ideal conditions were CIP concentration (50 ppm), pH 7, nanoparticles dosage (0.5 mg/ 50 mL) and 100 min of optimum contact time. In present paper, the response surface methodology (RSM) was applied as statistical tool used to optimize and model complex systems for elimination of CIP antibiotic from aqueous solution with selection the same four factors that mentioned above. The best appropriate isotherm model was the Freundlich model in batch study. The findings imply that hazardous compounds can be successfully eliminated from aqueous solutions using the prepared nanocomposites. The model's predictions aligned well with experimental outcomes, and the G-Fe/Cu nanocomposite effectively removed CIP from the solutions.

Eu3+ activated gadolinium oxide quantum dots: Biocompatible red luminescent phosphor for photonic, latent fingerprint imaging, and anticancer therapy

In this study, we employed a straightforward chemical reduction method to synthesize Gd2O3 quantum dots (QDs) doped with Eu3+ ions, yielding a remarkable red emission. X-ray diffraction (XRD) analysis confirmed the cubic structure of both pristine and Eu3+ doped Gd2O3 QDs. Characterization of particle size and elemental composition was accomplished through Transmission Electron Microscope (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. Photoluminescence analysis under UV excitation revealed a blue emission at 436 nm for the undoped Gd2O3 QDs. Furthermore, room temperature photoluminescence analysis was conducted on the undoped Gd2O3 quantum dots (QDs) with a UV excitation source. While Gd2O3 QDs emitted a blue light at 436 nm under 396 nm illumination, the Eu3+ doped Gd2O3 QDs exhibited a striking red luminescence under the same 394 nm wavelength. The red luminescence was notably enhanced in Gd2O3 QDs containing 0.5 mol% Eu3+ ions, although concentration quenching was observed when the concentration exceeded this level. A transfer of energy from pristine Gd2O3 QDs to Eu3+ ions was observed, leading to color purity exceeding 80.8% in the optimized sample. Notably, the 0.5 mol% Eu3+-doped Gd2O3 QD phosphor displayed non-cytotoxicity on C2C12 muscle myoblast cells while demonstrating remarkable cytotoxicity against MDA-MB-231 human breast cancer cells. This versatile material holds great promise for applications in latent fingerprinting, security coding, labeling, anticancer therapies, bio-imaging, and the advancement of lanthanide-doped QD phosphors for a wide range of photonic and biomedical applications.

Laser-thermal reduction synthesis of high-entropy alloys towards high-performance pH universal hydrogen evolution reaction

Owing to their multi-elemental compositions and unique high-entropy mixing states, high-entropy alloy (HEA) nanoparticles (NPs) displaying tunable activities and enhanced stabilities thus have become a rapidly growing area of research in recent years. However, the integration of multiple elements into HEA NPs at the nanoscale remains a formidable challenge, especially when it comes to the precise control of particle size, elemental composition and content. Herein, a simple and universal high-energy laser assisted reduction approach is presented, which achieves the preparation of HEA NPs with a wide range of multi-component, controllable particle sizes and constitution on different substrates within seconds. Laser on carbon nanofibers induced momentary high-temperature annealing (>2000 ​K and ramping/cooling rates > 105 ​K ​s−1) to successfully decorate HEA NPs up to twenty elements with excellent compatibility for large-scale synthesis (20.0 ​× ​20.0 ​cm2 of carbon cloth). The IrPdPtRhRu exhibit robust electrocatalytic hydrogen evolution reaction (HER) activities and low overpotentials of 16, 28, and 12 ​mV at a current density of 10 ​mA ​cm−2 in alkaline (1.0 ​M KOH), alkaline simulated seawater (1.0 ​M KOH ​+ ​0.5 ​M NaCl), and acidic (0.5 ​M ​H2SO4) electrolytes, respectively, and excellent stability (7 days and >2000 cycles) at the alkaline HER.

Characteristics of fine particle formation during combustion of high-alkali coal in a new full-scale circulating fluidized bed boiler

High-alkali coal generated an increased number of fine particles during the combustion process. Understanding the transformative characteristics of particulate matter (PM) in a full-scale boiler that burns 100 % Zhundong (ZD) coal is key for controlling pollutant emissions. This paper investigated PM formation in a novel full-scale Circulating Fluidized Bed (CFB) boiler. PM samples were collected from various points along the steam-cooled flue at 50 %, 67 %, and 100 % boiler load. Utilizing Low-pressure impactors and scanning electron microscopy coupled with energy disperse spectroscopy (SEM-EDS) were applied to analyze the mass-based particle size distribution(MPSD), elemental compositions, and morphology of PM. The results show that sub-micron particles produced under low boiler load consist primarily of AAEMs sulfates, whereas under high load, they consist primarily of alkali metal chlorides. Super-micron particles are predominantly sulfates and silicates. The concentrations of Na, K, and Cl in PM0.4 decreased as the flue gas cooled down in the steam-flue of the CFB. At 100 % boiler load, Na, K, Cl and S account for more than 90 % of the total elements in the sub-micron particles. However, these four elements demonstrated a 25 % decrease at a boiler load of 67 % compared to 100 % load. Interestingly, the compositions of super-micron particles seemed to be minimally affected by the boiler load.

On the Feasibility of Rugose Lipid Microparticles in Pressurized Metered Dose Inhalers with Established and New Propellants.

Pressurized metered dose inhalers (pMDIs) require optimized formulations to provide stable, consistent lung delivery. This study investigates the feasibility of novel rugose lipid particles (RLPs) as potential drug carriers in pMDI formulations. The physical stability of RLPs was assessed in three different propellants: the established HFA-134a and HFA-227ea and the new low global-warming-potential (GWP) propellant HFO-1234ze. A feedstock containing DSPC and calcium chloride was prepared without pore forming agent to spray dry two RLP batches at inlet temperatures of 55 °C (RLP55) and 75 °C (RLP75). RLPs performance in pMDI formulations was compared to two reference samples that exhibit significantly different performance when suspended in propellants: well-established engineered porous particles and particles containing 80% trehalose and 20% leucine (80T20L). An accelerated stability study at 40°C and relative humidity of 7% ± 5% was conducted over 3months. At different time points, a shadowgraphic imaging technique was used to evaluate the colloidal stability of particles in pMDIs. Field emission electron microscopy with energy dispersive X-ray spectroscopy was used to evaluate the morphology and elemental composition of particles extracted from the pMDIs. After 2weeks, all 80T20L formulations rapidly aggregated upon agitation and exhibited significantly inferior colloidal stability compared to the other samples. In comparison, both the RLP55 and RLP75 formulations, regardless of the propellant used, retained their rugose structure and demonstrated excellent suspension stability comparable with the engineered porous particles. The studied RLPs demonstrate great potential for use in pMDI formulations with HFA propellants and the next-generation low-GWP propellant HFO-1234ze.

Investigation of the photocatalytic activity of ceramic nanocomposite material based on BATIO3 with iron oxide

In this study, barium titanate was modified by introducing magnetite at 1 % and 10 % levels during sol-gel synthesis to determine the effects of ceramic nanocomposite composition on photocatalytic activity and structural features. Particle size, phase and elemental composition, and specific surface area were analysed. The proposed chemical reactions that occur during the preparation of a nanocomposite material and the resulting oxide forms of iron as a result of heat treatment are described. The second-order phase transitions were detected in the samples by differential scanning calorimetry. It was found that the average particle size of the powders tested did not exceed 205 nm. The band gap for the tested samples reduses with increasing proportion of iron oxide introduced: the band gap is 3.2 eV for BaTiO3, and for BaTiO3/1 % Fe3O4 - 3.2 eV. The photocatalytic activity of the powders during the decomposition of the organic dye rhodamine B was investigated. The proportion of decomposed dye on the catalysts in the aqueous solution was as follows: for BaTiO3 - 31 %, for BaTiO3/1 % Fe3O4 - 56 % and for BaTiO3/10 % Fe3O4 - 39 %. The influence of the phase composition and the system of barium titanate in the samples on the catalytic activity was determined. Possible mechanisms of photocatalytic degradation of the pollutant are considered. The operation of catalysts in cyclic mode was tested.

Elemental composition of particles formed during welding with stick electrodes

The elemental composition of welding fume (WF) respirable particles formed in carbon and low-alloy steels welding with stick electrodes with rutile (ANO-4) and the basic (UONI 13/45) type of coating was studied by X-ray-spectral electron-probe microanalysis. In the range from 0.25 to 16 µm aerodynamic diameter, all WF particles were divided into three groups according to their iron content: low (Fe≤20%), medium (20%<Fe<40%) and high (Fe≥40%). Each group contains various amounts of elements originating from the welding materials, which reflects their formation mechanism. Their relative abundance in WF depends on the particles aerodynamic diameter, type of electrode coating and the arc power. Particles with the medium iron content (agglomerates of nanosized primary particles) formed the largest group (over 70%) of respirable WF particles. For each electrode type, their average elemental composition does not depend on the size of the agglomerates. The low iron particles contain various combinations of electrode coating elements, and the variety of combinations increases with their aerodynamic diameter grows.These WF particles can be identified as aggregates of primary particles agglomerates and microspatters formed by disintegration of the electrode coating. WF particles with a high iron content are formed by aggregation of molten electrode metal microdroplets and nanosized primary particles agglomerates. They mainly contain iron (60–70%)and oxygen (15–35%). Their average elemental composition does not depend on the size of the aggregates, type of electrode coating and the arc power. The obtained results can be useful for the analysis and assessment of health risks for welders.

Eco-Friendly Pavements Manufactured from Mixed Recycled Aggregates Obtained from Construction and Demolition Waste: An Industrial-Scale Validation.

This study aimed to validate that laboratory-scale results could be commercially replicated when manufacturing marketable precast concrete. Construction and demolition waste (CDW) was separated into two (fine and coarse) recycled aggregates (RAs). Precast paver and kerb units were fabricated by partial or total substitution of natural aggregates (NAs) by RAs. The study involved the comprehensive characterisation of raw materials, including particle size distribution, mineral composition, and elemental composition. Paver blocks and kerbs manufactured with up to 50% RAs showed mechanical resistance (T = 3.7 ± 0.2 and B = 5.3 ± 0.6 MPa, respectively), water absorption between 5.3-5.7%, and abrasion resistance (approximately 20.2 mm), which met the standard requirements (UNE-EN 1340:2004 and UNE-EN 1338:2004). Furthermore, industrial-scale precast pavement units demonstrated strength and durability suitable for heavy traffic areas. A reduction of 13% in cement content could maintain the requirements with a partial RA substitution of 25%, offering economic and environmental benefits. Therefore, it is feasible at an industrial level to replace NAs with RAs, promoting durability and technological properties with a positive environmental impact and considerably reducing CO2 emissions by up to 65%. Overall, pavers with RAs manufactured at the laboratory scale met mechanical standards, and the kerb stones showed improvements in abrasion resistance. On an industrial scale, kerb stones and precast blocks with specific substitutions can meet strength, water absorption, and abrasion requirements, allowing a reduction in cement content.

Artemisia carvifolia Buch silver nanoparticles downregulate the Rap2A gene in liver cancer

Liver cancer is the second main reason of death globally. In the current study, Rap2A protein a member of Ras Gtpase was selected as a drug target for liver cancer which has been identified as an oncogene in different types of tumors. The present study aimed to evaluate Artemisia carvifolia Buch extract and its silver nanoparticles against liver cancer targeting the Rap2A gene. The synthesized silver nanoparticles showed an absorbance peak at 450 nm by a UV–Vis spectrophotometer. SEM revealed that polyhedral silver nanoparticles had a size ranging from 80 ± 6 nm. Furthermore, amines, aldehydes, ketones and alcohols of Artemisia carvifolia were found involved in the reduction and stabilization of nanoparticles by FTIR. Moreover, XRD and EDX confirmed the cubic crystalline nature and particle elemental composition, respectively. Furthermore, the cytotoxicity against HePG2 cancer cell lines was also found significant with an IC50 value of 2.57 µM for silver nanoparticles and 11.57 µM for plant extract. The gene expression and protein level of Rap2A were also decreased in plant extract and nanoparticle-treated cells compared to control groups. The apoptotic potential of extract and nanoparticles was also determined by evaluating the apoptotic pathway genes and protein including BAX, caspase 3, 8 and 9. Significantly elevated levels of expression of these genes by real-time qPCR along with increased protein levels by ELISA were found. This is the first-ever report describing the synthesis and efficacy of silver nanoparticles of Artemisia carvifolia Buch against liver cancer.

Reproducibility of physico-chemical properties in brakes emissions generated at the dynamometric bench

Reproducible generation, collection and physico-chemical characterization of brakes emissions are necessary when comparing particulates generated by different friction couples, brake designs or driving conditions. Furthermore, they are pivotal to provide universally reliable chemical information for source apportionment studies as well as for toxicological investigations and environmental assessments. Non-exhaust particulates generated by brakes are nowadays commonly collected at suitably designed variable inertia dynamometer benches, during selected braking test cycles in controlled conditions to avoid other contributions from the environment. In spite of being simplified models of a single real car semi-axis corner, dynamometric benches for brakes emissions collection still remain elaborate mechanical devices used for testing complex materials. Therefore, if the tribological interaction is not kept constant over different tests, significantly different local forces and temperatures might be expected at the tribological interface. This can eventually result in the generation of particulates with different granulometry and chemical composition, even if originated by the same braking device components. At this regard, the work here presented explores for the first time the capability of a brake dynamometer bench dedicated to emission tests to generate reproducible particulates. In particular, the assessment of the intrabench reproducibility over an extended period of time and number of tests is discussed. Specifically, the variability of physico-chemical properties such as particle size distribution, elemental composition and crystalline phase distribution is evaluated. In detail, it is observed that the elemental concentration of main constituents such as Iron and Oxygen are statistically equivalent during a set of ten tests, even at strict confidence level (α = 0.05). In addition, when statistical differences are observed in elemental concentration of secondary and minor constituents, their variability typically remains limited below the 10 % of the corresponding figure of merit. Similar findings are also observed when assessing the phase composition of main constituents compounds, such as Iron oxides, as well as the particle size distribution profiles. Conversely, higher relative variabilities up to 25 % are registered when assessing the phase composition of secondary and minor phases. The reported results are meant to provide a first critical assessment on the variability of both the size distribution and the chemical composition of the emissions generated by brakes in the laboratory environment typically used for their generation, measurements and collection.

Morphological and chemical characterisation of indoor quasi-ultrafine particles

Particles in the nanoscale range have intrinsic physicochemical characteristics that define their interaction with the human body and ultimately their toxicity. Whilst research has focused on engineered nanomaterials or ambient ultrafine particles, little is known about the morphology, size and elemental composition of particles in the nanoscale range collected in indoor environments, where humans spend the longest time. This study aims to characterise the physicochemical properties of quasi-ultrafine particles (qUFP), with an aerodynamic diameter <250 nm, collected with a Sioutas impactor from 5 indoor environments (3 homes and 2 offices). Morphology, size and elemental composition of individual particles were imaged using a Transmission Electron Microscope coupled with X-ray energy dispersive spectroscopy. Most of the single particles and their aggregates were of irregular shapes, and some fibrous rods, elongated rods, spheres and hexagons were also observed. ImageJ software was used to analyse the surface area, roundness and circularity of the particles, as well as individual particle diameter for the spherical particles. For the non-spherical shaped particle, the particles were manually measured to characterise the maximum Feret diameter. Particle main dimensions (i.e. diameter for spheroids and maximum Feret diameter for irregular particles) ranged from 35 ± 59 nm to 103 ± 160 nm. Shapes for non-spherical particles were assigned by visual description. Si, Fe and S were found in nanoparticles from all indoor locations. Other abundant constituents were K, Cr, Na, Ca, Cl found in 60–80% of locations. Minor constituents of indoor nanoparticles were Cu, Sn, Ti, Mo, Al, P, Be, F, Zn, Rb, Pb, Mn and Co. Sources were related to indoor emissions, e.g. printers, stainless-steel tools, electronics, cooking, house chores, particle re-suspension, aerosol and cleaning products as well as to penetration of outdoor nanoparticles from vehicular emissions, soil and secondary aerosols. Detailed investigation of the physicochemical properties of these particles can help understand their associated hazard and their fate in the human body.

Novel Modified Styrene-Based Microspheres for Enhancing the Performance of Drilling Fluids at High Temperatures.

Ensuring wellbore stability is of utmost importance for safety when drilling in deep formations. However, high temperatures severely disrupt the drilling fluid gel system, leading to severe stability issues within ultra-deep formations containing micropores. This study focused on the development of a polymer-based plugging material capable of withstanding high temperatures up to 200 °C. A kind of microsphere, referred to as SST (styrene-sodium styrene sulfonate copolymer), was synthesized with a particle size of 322 nm. Compared to polystyrene, the thermal stability of SST is greatly improved, with a thermal decomposition temperature of 362 °C. Even after subjecting SST to hot rolling at 200 °C for 16 h, the particle size, elemental composition, and zeta potential remained stable within an aqueous dispersion system. The results of core displacement and NMR tests demonstrate that SST considerably reduces the pore diameter with a remarkable plugging efficiency of 78.9%. Additionally, when drilling fluids reach 200 °C, SST still enhances drilling fluid suspension and dispersion, and reduces fluid loss by over 36% by facilitating the dispersion of clay particles, improving the gel structure of the drilling fluid, resisting clay dehydration, and promoting plugging. The development of SST provides valuable insights into the preparation of high-temperature-resistant microspheres and the formulation of effective plugging agents for deep-well drilling fluids.

Synthesis, Characteristation and Biological Activity of Silver Nanoparticles Generated Using the Leaf and Stembark Extract of Combretum erythrophyllum.

Medicinal plants are known to contain numerous phytometabolites with suggested pharmacological value. Literature suggests that the medicinal use of phytometabolites in its natural state has limited success due to poor absorption rates. Currently, the focus lies on synthesizing phytometabolites extracted from medicinal plants and silver ions to generate nano-scale carriers with specialized properties. Thus, the nano-synthesis of phytometabolites with silver (Ag+) ions is proposed. The use of silver is promoted due to its known antibacterial and antioxidant effectiveness, among many. Nanotechnology allows for the green generation of nano-scaled particles that are able to penetrate target areas due to its size and unique structure. Therefore, this study aimed to generate a novel protocol for the synthesis of AgNP's using the leaf and stembark extracts of C. erythrophyllum. In addition, the biological activity of the generated nanoparticles was evaluated. To synthesis silver nanoparticles (AgNP's) using the leaf and stembark extracts of Combretum erythrophyllum. The relative shape, size, distribution, and zeta potential of the synthesised particles were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX), Nanoparticle tracking analysis (NTA), and UV Spectrophotometry (UV -vis). To screen the synthesised particles for its potential antibacterial, apoptotic and cytotoxic properties. A novel protocol for the synthesis of silver nanoparticles (AgNP's) using the leaf and stembark extracts of Combretum erythrophyllum was established. The generated AgNP's were characterised using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX), Nanoparticle tracking analysis (NTA), and UV Spectrophotometry (UV -vis). Furthermore, the AgNP's were evaluated for their antibacterial, cytotoxic and apoptotic activity against a range of bacterial strains and cancer cells. Characterisation was based upon particle size, shape and elemental silver composition. Within the stembark extract, synthesised nanoparticles were large, spherical in shape and dense in elemental silver composition. While synthesised nanoparticles of the leaf extract were small to medium in size, varied in shape established and contained minimal quantities of silver (substantiated by the TEM and NTA results). Furthermore, it was established that the synthesized nanoparticles exhibited high antibacterial properties due to the conducted antibacterial assay. The FTIR analysis revealed the presence of numerous functional groups within active compounds found in the synthesised extracts. Functional groups found varied between the leaf and stembark extracts, each with proposed pharmacological activity. Presently, antibiotic-resistant bacteria are continuously evolving thus, posing as a threat to conventional drug delivery systems. Nanotechnology provides a platform that enables the formulation of a low-toxicity and hypersensitive drug delivery system. Further studies evaluating the biological activity of extracts of C. erythrophyllum synthesized with silver nanoparticles could enhance its proposed pharmaceutical value.

Optical and radiation shielding properties of PVC/BiVO4 nanocomposite

This study investigates the physical and optical properties as well as the radiation shielding capacity of polyvinyl chloride (PVC) loaded with x% of bismuth vanadate (BiVO4) (x = 0, 1, 3, and 6 wt%). As a non-toxic nanofiller, the designed materials are low-cost, flexible, and lightweight plastic to replace traditional lead, which is toxic and dense. XRD patterns and FTIR spectra demonstrated a successful fabrication and complexation of nanocomposite films. In addition, the particle size, morphology, and elemental composition of the BiVO4 nanofiller were demonstrated through the utilization of TEM, SEM, and EDX spectra. The MCNP5 simulation code assessed the gamma-ray shielding effectiveness of four PVC + x% BiVO4 nanocomposites. The obtained mass attenuation coefficient data of the developed nanocomposites were comparable to the theoretical calculation performed with Phy-X/PSD software. Moreover, the initial stage in the computation of various shielding parameters, such as half-value layer, tenth value layer, and mean free path, besides the simulation of linear attenuation coefficient. The transmission factor declines while radiation protection efficiency increases with an increase in the proportion of BiVO4 nanofiller. Further, the current investigation seeks to evaluate the thickness equivalent (Xeq), effective atomic number (Zeff), and effective electron density (Neff) values as a function of the concentration of BiVO4 in a PVC matrix. The results obtained from the parameters indicate that incorporating BiVO4 into PVC can be an effective strategy for developing sustainable and lead-free polymer nanocomposites, with potential uses in radiation shielding applications.

Emissions and Exposures Associated with the Use of an Inconel Powder during Directed Energy Deposition Additive Manufacturing.

Additive manufacturing (AM) has been linked to potential exposure-related health risks, however, there is a paucity of sufficient research. This study aimed to supply information regarding emissions and exposure during directed energy deposition (DED) AM using inconel 718, with the main constituents being nickel, chromium, and cobalt. By using standardized occupational hygiene methods, the measurement strategy consisted of a combined approach, including powder characterization, particle emission monitoring, and personal exposure monitoring of AM operators. Powder characterization of virgin and used powder indicated no significant difference in particle size, shape, or elemental composition. Particle number emissions ranged between 102 and 105 p/cm3 for submicron particles (<1 µm in size). There was no significant difference in the particle emission rate between the three phases of AM or the two types of DED machines (p > 0.05). The particle emission rate for submicron particles peaked at 2.8 × 109 p/min. Metals of concern to human health were detected during the AM process but were considerably lower than the relevant exposure limits. This study confirms particle emissions, predominantly in the submicron range, above the background concentration during DED AM and, although insignificant in terms of potential health effects, AM operators are exposed to detectable concentrations of the metal constituents of inconel.