Composite Particles Research Articles

Bi-functional hydrogen tungsten bronze/carbon composite catalysts towards biomass conversion and solar water purification

We presented a novel bi-functional catalyst composed of HxWO3 and carbon composites, which exhibits excellent catalytic activity in biomass conversion and has the ability to effectively purify water via a wide range of wavelengths in the light spectrum. The HxWO3/carbon composites were effectively produced from commercially available monoclinic tungsten trioxide (WO3) and polypropylene (PP) powders to a single-step mechanochemical reaction employing high-energy ball milling. We systemically investigated how different synthesis parameters, such as rotation speed, processing duration, and ball diameter, affect the mechanochemically-induced phase transformation to either tetragonal or cubic HxWO3 during planetary ball milling. The crystal phase of HxWO3 was controllable by altering the total impact energy in the ball milling. In addition, real-time monitoring of the pressure increment inside the pot and evaluation of the evolved gas revealed the degassing behavior through the oxidative degradation of PP assisted by WO3. The CV and Rietveld analysis proved that HxWO3 exhibited significant enhancement by two orders of magnitude in the rate of H+ diffusion compared to monoclinic WO3. This enhancement would be attributed to the expansion of a mechanically-formed tunnel along the a-axis, which facilitates the migration of H+ ions. The HxWO3/carbon composites performed approximately 12-fold higher efficiency in generating soluble solids (glucose and furfural derivatives) compared to untreated WO3 through the catalytic hydrolysis of cellulose, owing to the enhanced Brønsted acidity. Moreover, the composite particles showed broad light absorption in the UV–Vis–NIR range and demonstrated a considerable enhancement of over three orders of magnitude in the photocatalytic degradation of methyl orange pollutants when exposed to NIR and visible light.

Morphology and elemental composition of individual solid dust particles: From different sources to the atmosphere

This study investigates the morphology and elemental composition of individual solid dust particles from various sources (e.g., thermal power plant, domestic coal combustion, building construction dust, wind-blown dust, Asian dust storm, and road related dust) to the atmosphere under high and low relative humidity (RH) conditions in a coastal city of north China by using high-resolution electron microscopes. The results showed that distinct variations between dust particles from thermal power plant and domestic coal combustion, despite both using coal as fuel. Specifically, 88.6% (by number) of thermal power plant particles were spherical, whereas only 2 out of 347 particles from domestic coal combustion exhibited a spherical shape. Furthermore, domestic coal combustion particles showed a higher proportion of Ca-rich particles compared to those from thermal power plant. The wind-blown dust and Asian dust storm particles were mainly “Si + Al” subtype (52.0% v.s. 75.3%) and Si-dominant subtype (16.4% v.s. 11.7%) particles, which were mainly from crustal sources. However, wind-blown dust contained a higher fraction of Ca-rich (11.6%) and Fe-rich (5.3%) particles than Asian dust. The building construction dust particles primarily consisted of irregular Ca-dominant (39.4%) and “Ca + Si” subtype (29.8%) particles. Road related dust were also mainly Si-rich particles (52.9%), likely from re-suspended soil, along with a notable presence of spherical (8.0%) and Fe-rich particles (19.3%), possibly linked to vehicle emissions and brake wear. Additionally, relative number percentage of Na-rich particles and the average weigh ratios of Na in the atmospheric particles were higher than those from all above-mentioned source samples, suggesting that sea-salt related particles might be an important source of the atmospheric dust at the coastal city. The results indicated that Ca-rich particles were significantly modified by S and NaCl particles might lose Cl through heterogeneous reactions under higher RH.

Study on the effect of rare earth elements La, Ce, Y and Sc doping on the mechanical properties of aluminum–lithium alloys

In this paper, the effects of rare earth elements La, Ce, Sc, and Y on the bond strength of the aluminum–lithium alloy δ’ (Al3Li)/Al interface are investigated using first-principles calculations. The results show that the interfacial energy decreases after substitutional doping of Al atoms on both sides of the interface by rare earth elements, respectively, with values ranging from −2.0664 eV/Å2 to −1.9720 eV/Å2. The interfacial energy decreased by 2.0841 eV/Å2 and 2.0709 eV/Å2 when Ce and Sc elements replaced Al in the matrix, respectively. Uniaxial interfacial tensile simulations of Al/ Al3Li showed that the strain elongation of the material increased from 24 % to 42 % for the pure interface after doping with Sc elements at the interface. The same tensile tests yielded a maximum elongation at break of 3.25 % for Al-Li alloy after artificial aging at 0.6 % Sc content. Observation of the microstructure of the materials before and after rare earth doping using TEM reveals that the content of nanoscale Al3(Sc, Li) composite particles increases with the increase of Sc content after artificial aging at 185 °C for 10 h. Moreover, the presence of Al3Sc refines the precipitated phase of the alloy and improves the plastic toughness of the material.

The effects of photochemical aging and interactions with secondary organic aerosols on cellular toxicity of combustion particles

Fine particulate matter (PM2.5) is associated with numerous adverse health effects, including pulmonary and cardiovascular diseases and premature death. Significant contributors to ambient PM2.5 include combustion particles and secondary organic aerosols (SOA). Combustion particles enter the atmosphere and undergo an aging process that changes their shape and composition, but there is limited study on the health effects of combustion particle aging and interactions with SOA. This study aimed to understand how biological responses to combustion particles would be affected by atmospheric aging and interaction with anthropogenic SOA. Fresh combustion particles underwent photochemical aging in a potential aerosol mass (PAM) oxidation flow reactor and interacted with SOA produced by the oxidation of toluene vapor in the PAM reactor. Photochemical aging and SOA interactions lead to significant changes in the PAH content and oxidative potential of the particle. Photochemical aging and SOA interactions also affected the biological responses, such as the inflammatory response and CYP1A1 induction of the particles in monoculture and coculture cells. These findings highlight the significance of photochemical aging and SOA interactions on the composition and cellular responses of combustion particles.

DMRG study of the theta-dependent mass spectrum in the 2-flavor Schwinger model

We study the θ-dependent mass spectrum of the massive 2-flavor Schwinger model in the Hamiltonian formalism using the density-matrix renormalization group (DMRG). The masses of the composite particles, the pion and sigma meson, are computed by two independent methods. One is the improved one-point-function scheme, where we measure the local meson operator coupled to the boundary state and extract the mass from its exponential decay. Since the θ term causes a nontrivial operator mixing, we unravel it by diagonalizing the correlation matrix to define the meson operator. The other is the dispersion-relation scheme, a heuristic approach specific to Hamiltonian formalism. We obtain the dispersion relation directly by measuring the energy and momentum of the excited states. The sign problem is circumvented in these methods, and their results agree with each other even for large θ. We reveal that the θ-dependence of the pion mass at m/g = 0.1 is consistent with the prediction by the bosonized model. We also find that the mass of the sigma meson satisfies the semi-classical formula, Mσ/Mπ = 3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{3} $$\\end{document}, for almost all region of θ. While the sigma meson is a stable particle thanks to this relation, the eta meson is no longer protected by the G-parity and becomes unstable for θ ≠ 0.

Combustion and mechanical properties enhancement strategy based on stearic acid surface activated boron powders

Boric acid and other impurities on the surface of boron (B) particles can interact with hydroxyl-terminated polybutadiene (HTPB), weakening the mechanical properties and energy release efficiency of boron-based solid rocket propellants. SA@B composite particles were created by coating stearic acid (SA) on the surface of B particles through solvent evaporation-induced self-assembly. The study investigated the impact of SA coating on the combustion performance of B particles and the mechanical properties of HTPB matrix composites. The results showed that the SA coating enhanced the oxidation efficiency of B particles in air. The combustion heat of SA@B composite particles is 30.29 MJ/g, about 50% higher than that of B particles. During the combustion of SA@B composite particles, fewer molten solid particles surround the flame, which enhances the stability of the combustion process of the B particles. Furthermore, the SA coating effectively enhanced the dispersion of B particles in HTPB. At a stretching speed of 100 mm/min, the tensile strength of the SA@B/HTPB composite materials is higher than that of the B/HTPB composite materials. Moreover, when the mass loading of the SA@B composite particles reaches 50 wt%, the tensile strength of SA@B/HTPB composite materials is 2.46 MPa. Activating the surface of boron particles with SA can significantly improve their compatibility with HTPB, which is crucial for the stable storage of boron-based solid rocket propellants.

Morphological Characteristics of W/Cu Composite Nanoparticles with Complex Phase Structure Synthesized via Reactive Radio Frequency (RF) Thermal Plasma

The W/Cu binary system is characterized by its mutual insolubility and excellent wettability, making W/Cu composite materials ideal for managing thermal and electrical properties in electronic components. To optimize material properties, control over the microstructure is crucial, and nanocomposites with uniform dispersion offer significant advantages. In this study, W/Cu composite nanoparticles were synthesized by feeding a blended feedstock of tungsten trioxide (WO3) micro-powder and cupric oxide (CuO) micro-powder into a reactive radio frequency (RF) argon–hydrogen thermal plasma system. Cu-coated W nanocomposite particles were obtained through the vaporization, reduction, and condensation processes. The resulting nanocomposite particles were composed of body-centered cubic (BCC) α-W, A15 β-W, and face-centered cubic (FCC) Cu phases, with a chemical composition closely matching theoretical calculations. The phase evolution and morphological changes of the synthesized particles were analyzed as a function of heat treatment temperatures up to 1000 °C in a reducing atmosphere. Up to 600 °C, the phase composition and morphology remained stable. At 800 °C, localized diffusion and coalescence of Cu led to the formation of particulate Cu, and a significant phase transformation from metastable β-W to α-W was observed. Additionally, extensive Cu segregation due to long-range diffusion resulted in distinct Cu-rich and Cu-depleted regions. In these regions, notable sintering of W particles and the complete disappearance of β-W occurred. The results showed that the temperature-dependent redistribution of Cu plays a crucial role in the phase transformation of W and the morphology of W/Cu composite particles.

Mechanisms of Pickering emulsion formation and stabilization by composite arabinoxylan–whey protein isolate particles

Few systematic studies were performed into the properties of arabinoxylan (AX) and protein composite particles, and their mechanisms of action in an emulsion remain largely unknown. In this study, composite particles based on different concentrations of AX and whey protein isolate (WPI) were constructed, and a systematic characterization was conducted to determine their functional properties. A good compatibility was found between WPI and AX, and the composites exhibited an enhanced thermal stability and consistent particle sizes. Molecular interactions, including hydrogen bonds, were detected between WPI and AX, and the composite particles containing 4% AX exhibited the lowest interfacial tension and the strongest emulsification ability. AX promoted protein adsorption on the oil phase surface, and the desorption energy of the composite particles at the oil/water interface increased accordingly. The stability of an emulsion stabilized by AX–WPI was confirmed by rheological and microstructural investigations. This study therefore provides theoretical support for the application of such emulsions.

Soil cross breeding: Mechanical strength analysis of intermixed soils used as unfired earth brick

Mechanical strength of brick is significantly influenced by soil properties, deeming some soils unusable. This paper investigates the effect of mixing soils from different sources, Hyogo (a chlorite soil) and Tokyo (an albite soil) from Japan, on the flexural and compressive strength of unfired earth brick. Before conducting strength tests on moulded bricks made from original soil mixes and intermixed soils, both soil samples were individually separated into two portions, sand and fines. To better understand the strength behaviour of the resulting brick specimen, the physical and chemical properties of used raw materials were characterised using various techniques including X-ray computed tomography (X-ray CT) X-ray diffraction (XRD), water and nitrogen sorption, X-ray fluorescence (XRF) and ionic conductivity. The results revealed that the replacement of the fines portions in unadulterated soil mixes induced an increase in flexural and compressive strength for brick specimen made with albite soil, while significant reduction in strength was recorded with brick specimen made with fines portion replaced in chlorite soil. Furthermore, the former intermixed soil exhibited higher strengths than specimen made from unadulterated soils. Chlorite clay minerals comprised of desired properties to enhance performance of albite soil sand particles in a brick composite. This justified the dependence of selected soil parameters that play critical roles in the performance behaviour of the produced bricks. The obtained findings could serve as guidelines to production and performance enhancement of unburnt brick by amalgamating various soils.

Morphology and chemical composition of mineral particles in a special dust storm with high relative humidity in North China

A special dust storm characterized by high PM10 mass concentrations (921.9 ± 632.3 μg m−3) and high relative humidity (RH; 60.1 % ± 11.1 %) was observed on March 22–24, 2023 at a coastal city of North China. Aerosol particles of PM10 were analyzed by a scanning electron microscope coupled with energy dispersive X-ray and an ion chromatograph. The results showed that individual mineral particles were dominated by clay minerals, followed by quartz, feldspar, and carbonate. Bulk water-soluble inorganic ions analysis showed that SO42- mass concentrations varied from 3.7 μg m−3 to 23.3 μg m−3 with an average value of 12.4 μg m−3. However, their mass ratios to PM10 were relatively stable, being 1.15–2.01 % with an average value of 1.49 % ± 0.25 %, similar to the value near the dust sources (Tengger Desert). Although S-containing individual mineral dust varied from 5.2 % to 70.7 %, the average weight ratio of S on individual mineral dust was 2.1 %, much lower than that of non-dust periods (11.0 %). The results suggested limited sulfate formation on mineral dust surfaces even under high RH. In contrast, NO3-, which was very limited in dust sources, varied from 0.21 % to 4.11 % of the total PM10 with an average value of 1.61 % ± 1.07 %. The research highlighted that nitrate formation has exceeded sulfate formation during severe dust storm episodes, which might because the atmospheric compositions in China have changed significantly with a high mass ratio of NO2/SO2 after the implementation of the strict emission control measures.

Simulation and experimental study of tool passivation based on magnetic elastic abrasive particles

The presence of micro-cracks and serrations on the tool often leads to its premature failure. However, these microscopic defects can be mitigated through passivation treatment of the tool. Magnetoelastic abrasive particles are new composite particles formed by using abrasive phase particles, magnetic media phase particles and polymer matrix according to a certain ratio, the abrasive particles have both viscoelasticity and magnetic conductivity. The introduction of magnetoelastic abrasive grains into the dual-disk tool passivation equipment can effectively improve the surface quality of the tool and increase the passivation efficiency. At the outset, a model for tool passivation was crafted employing the ABAQUS simulation software. This model aimed to evaluate the effects of diverse passivation variables on the stress levels, the shape of the impact, and the depth of the impact experienced by the tool. Subsequently, by applying statistical theory combined with fitting function techniques, a mathematical model was constructed to determine the passivation volume of the tool subjected to multiple magnetic elastic abrasive particles. This model was then used to examine the impact count and passivation volume associated with each passivation factor. Finally, a tool passivation experiment was conducted using a dual-disk magnetic tool passivation device. The results showed that the smaller the impact velocity of magnetic elastic abrasive particles, the stress and impact depth of the cutting tool are decreasing, and the deformation of the cutting edge is caused by compressive stress. The error of impact depth calculated by simulation and mathematical model is within 20 %, which proves that the mathematical model can better calculate the impact depth of magnetic elastic abrasive particles on the cutting edge of the tool.

A novel Pickering emulsion gels stabilized by cellulose nanofiber/dihydromyricetin composite particles: Microstructure, rheological behavior and oxidative stability

Particle concentrations (w) and oil content (Φ) are crucial factors influencing the gel stability of Pickering emulsions. To understand the stabilization mechanism comprehensively, we prepared emulsion gels stabilized by CNF/DMY composite particles at various w (0.5–1.5 wt%) and Φ (0.2–0.6, v/v). The microstructure revealed the adsorption of these particles at the oil-water interface, with excess particles forming a three-dimensional network structure in the continuous phase. Rheological studies showed that the network structure of Pickering emulsions was significantly influenced by w and Φ, resulting in improved emulsion gel strength that hindered the movement of oil droplets and oxygen in the continuous phase, thereby enhancing emulsion stability. Three scenarios for the critical strain (γco) were observed: at Φ = 0.2, γco decreased with increasing w, while at Φ = 0.4, γco increased with increasing w. At Φ = 0.6, γco remained relatively constant regardless of w. In conclusion, adjusting particle concentration and oil content enabled the control of microstructure, rheological properties, and antioxidant capacity of emulsion gels. These findings could be a valuable resource for formulating and ensuring the quality of emulsion gel-based products in the food industry.

Photorheologic Silicone Composites with Adaptive Properties by Utilizing Light‐Degradable Organosilica Nanoparticles as Fillers

AbstractImplementing inorganic filler particles is a powerful method for improving the mechanical properties of polymer composites. The physical properties are determined by the interaction of the filler with the polymer. Thus, factors like the surface‐to‐volume ratio and surface modification are important. Besides the strategies of influencing these physical properties by a prior modification of the filler, this approach applies a post‐treatment of the composite. The present publication focuses on bringing stimuli‐responsive properties to a composite material by changing the chemical composition and structure of the filler particles. Instead of creating a responsive polymer, the concept is to use photo‐degradable organosilica nanoparticles that can change the mechanical properties of a polymer/filler composite after it has been prepared. After the synthesis of nitrobenzyl ether containing organosilica nanoparticles and the investigation of the photochemical processes, the preparation of the composites with silicones is described. Vinyl groups are attached to the surfaces to secure a homogeneous distribution of the filler particles inside the polymer matrix. After light‐induced decomposition, the mechanical properties are investigated. Other than expected, the material becomes stiffer, which is explained by an increase in the surface area of the silica particles, accompanied by the emergence of hydroxy groups that interact with the polysiloxane.

Mineralogical Insights into PGM Recovery from Middle Group (1–4) Chromite Tailings

Variations in the recovery of platinum group metals (PGMs) are often attributed to mineralogical and other natural ore-type variations. To increase the recovery of PGMs by the flotation process, a comprehensive understanding of gangue and valuable minerals is essential for optimising the extraction and processing of metals. Recoveries may be improved if the questions of how, where, and why losses occur can be answered with a certain degree of confidence. A requirement is the availability of statistically reliable mineralogical data. The PGMs of MG-1–4 chromite tailings dumps of the western limb of the Bushveld complex (BC) were studied in detail to unravel the PGMs and the nature of the platinum group minerals in the sample. Characterisation of the chromite tailings via deportment analysis revealed that the sample contained a significant amount of 3E PGM + Au (Pt, Pd, Ru, and Au) and was concentrated in the -25 µm fraction. The results of automated mineralogical analysis showed that the sample was composed of the PGE-sulphides group, comprising 63.6 vol%, PGE-sulfarsenides 10.4 vol%, PGE-arsenides 1.3 vol%, PGE-bismuth tellurides 3.3 vol%, PGMs-alloy 4.1 vol%, and Laurite comprising 17.3 vol% of the total PGE population. The sample was composed of 66.5 vol% of liberated PGMs, 0.2 vol% attached to liberated BMS, 27.3 vol% of PGMs attached to or locked within silicate or oxide gangue composite particles, 0.2 vol% of PGMs associated with BMS attached to silicate or oxide gangue particles, and a low proportion (5.8 vol%) of PGMs reported being locked within gangue or oxide particles. The majority of PGM grains observed were reported in the fast-floating category (64.4 vol%), 27.6 vol% in the slow-floating 1 category, 2.2 vol% in the slow-floating 2 category, and 5.8 vol% to the non-floating category. The results of the study revealed that the PGMs of MG 1–4 chromite tailings were liberated; however, the low liberation index (<0.2) suggested that a significant portion of PGMs remained trapped within gangue, hindering their recovery. This highlights the need for effective comminution (crushing and grinding) to achieve better liberation. The sample contained fine particles that were more prone to being lost in the tailings and to lowering recovery due to the slimes coating valuable minerals. The recovery of the PGMs from this complex’s polymetallic bodies of low-grade and complex mineralogy will be insufficient with traditional methods and thus innovation is needed. Innovation like advanced comminution, novel flotation equipment or reagents, selective leaching and bioprocessing can overcome these challenges.

Volcanic ash in the water column: Cellular, physiological and anatomical implications for the gastropod suspension-feeder Crepipatella peruviana (Lamarck, 1822)

The influx of volcanic ash into seawater alters particle composition with implications for the cellular, physiological and anatomical response of suspension-feeding organisms. Adult females of Crepipatella peruviana were exposed to three diets consisting of a fixed concentration of 50,000 cells ml−1 of the microalga Isochrysis galbana plus different concentrations of ash particles (30, 90 and 150 mg L−1). The objective was to determine the cellular, physiological and anatomical responses. Mortality increased with ash concentrations, while feeding and respiration rates, tissue weight, and condition index decreased. The gills showed severe degradation of cilia and the presence of large mucous aggregates of cilia and ash. An increase in ash resulted in decreased lipid peroxidation and protein carbonyls, but increased total antioxidant capacity and phenols. Thus, volcanic ash particles may exert a high impact at both cellular and physiological levels for C. peruviana, where inhibition of gill function reduces the ability to acquire food.

Research of two kinds of PANI@semiconductor based photocathodic coating corrosion protection effect and mechanism

PurposeThis study aims to report the development and experimental evaluation of two kinds of PANI@semiconductor based photocathodic anti-corrosion coating, for application on stainless steel substrates.Design/methodology/approachPANI was in situ chemical polymerized on TiO2 and BiVO4 particles, and FT-IR and SEM/EDS were used to understand the characteristics and elemental distribution of the composite particles. Composite coatings, which consisted of epoxy, PANI@TiO2 or PANI@BiVO4 and graphene, were prepared on the 304L stainless steel. Photoelectrochemical response measurement, electrochemical tests and immersion tests were used to assess the anti-corrosion performance of the prepared coatings in 45°C 3.5 wt.% NaCl solution. And the corrosion protection mechanism was further explained by combining with surface observation.FindingsThe photoelectrochemical response tests revealed the good photocathodic effect of the coatings, and the reversible oxidation-reduction properties of PANI (pseudocapacitive effect) leading to the repeated usage of the coatings. Consequently, the anti-corrosion mechanism of the composite coating is attributed to the physical barrier effect of the coating, the anodic protection effect of PANI and the photocathodic and energy store effect.Originality/valueThese kind coatings could prevent corrosion from day to night for stainless steel, which has great engineering application prospects on stainless steel corrosion protection.

The effect of carbon fiber length on the thermal expansion of fiber‐reinforced particulate hybrid composites

AbstractThermal expansion of materials is a critical factor influencing their dimensional stability. This study explores the regulation of thermal expansion in composite materials through the incorporation of carbon fibers and zirconium tungstate particles. The influence of fiber length on the thermal expansion behavior of these composites was investigated. The investigation reveal that the variation in the relative elongation ratio (dl/L0) of the carbon fiber‐reinforced zirconium tungstate composites is nonlinear, characterized by an initial increase, subsequent decrease, and a final resurgence. Notably, an increase in fiber length results in a mitigated rate of increase in the (dl/L0) ratio. Furthermore, composites fabricated with shorter fibers exhibit a higher coefficient of thermal expansion (CTE). Upon elevating the temperature to 250°C, the CTE for composites reinforced with 100 and 500 mesh carbon fibers escalate to 24.5 × 10−6/K and 74.6 × 10−6/K, respectively. These values represent an 8% and 116% enhancement relative to those measured at 50°C.Highlights The thermal expansion properties are improved by adding carbon fiber and ZrW2O8 nanoparticles. Utilizing fiber lengths ranging from 100 to 500 mesh effectively diminishes the CTE. The Cf‐ZrW2O8/9621 composite exhibits non‐linear behavior in its dl/L0 ratio. Within the range, longer fibers are more beneficial for reducing the CTE.

The Effect of Nickel Content and Mechanical Activation on Combustion in the 5Ti + 3Si + <i>х</i>Ni System

Intermetallic alloys were synthesized in the 5Ti + 3Si + xNi system by the method of self-propagating high-temperature synthesis (SHS) and mechanosynthesis. The influence of nickel content on the morphology, size and yield of composite particles after mechanical activation (MA) of mixtures was studied. The dependences of the maximum temperatures and combustion rates, phase composition, morphology and elongation of synthesis products on the nickel content for the initial and MA mixtures are studied. Under the conditions of the experiments conducted in this work, combustion process was able to realize and at the same time the samples burned completely at a nickel content of 10 to 60 wt.% in the 5Ti + 3Si + xNi system. After MA, the samples from the 5Ti + 3Si mixture burned to the end, and during the activation of the 5Ti + 3Si + 40% Ni mixture, mechanochemical synthesis occurred. With increasing nickel content combustion temperature decreases, and combustion velocity behaves nonmonotonically, increases the size of composite particles and decreases the yield of the mixture after MA. MA practically did not affect the maximum combustion temperatures of mixtures of 5Ti + 3Si + xNi. A multiple (from 0.7 to 2.9 cm/s) increase in the burning rate of samples from MA mixtures with an increase in the Ni content from 20 to 30 wt. % was recorded. An increase in the nickel content leads to an increase in the content of triple phases and the amount of melt in the synthesis products of mixtures of 5Ti + 3Si + xNi. Shrinkage of product samples increases with increasing nickel content in the initial mixtures. After MA, the shrinkage of the product samples is replaced by their growth. Explanations of the observed dependencies are proposed.

Size-segregated content of heavy metals and polycyclic aromatic hydrocarbons in airborne particles emitted by indoor sources

Indoor air quality is negatively affected by the emission of different combustion sources releasing airborne particles and related particle-bound toxic compounds (e.g., heavy metals and polycyclic aromatic hydrocarbons). To date, very few studies focused on the chemical characterization of the airborne particles emitted by indoor sources were carried out; moreover, no data on their size-resolved chemical compositions are available. In the present study, an experimental analysis aimed at determining the size-segregated content of heavy metals and polycyclic aromatic hydrocarbons in airborne particles (including sub-micrometric ones) emitted by widely-used indoor combustion sources (i.e., incenses, candles, mosquito-coils, and cooking activities) was carried out. To this purpose, airborne particles were collected through an electric low-pressure impactor and were post-analyzed by means of chromatography–mass spectrometry and atomic emission spectrometry techniques. Results of the analyses showed that the chemical composition of the emitted particles is not invariant to the particle size, indeed, an important contribution of sub-micrometric particle range to the total mass of chemical compounds emitted by the sources was noticed. These findings also demonstrated that significant underestimations of particle-bound compounds depositing in the lungs could occur if size-dependent compositions are not adopted.

Revolutionizing Bone Regeneration with Grinder-Based Dentin Biomaterial: A Systematic Review.

Bone tissue regeneration is a critical aspect of dental surgery, given the common occurrence of bone resorption leading to alveolar bone defects. The aim of this paper was to conduct a systematic review to provide a comprehensive summary of the evidence regarding the regenerative properties of dentin biomaterial. This systematic review was conducted through comprehensive searches in the PubMed, Scopus, and Web of Science databases, as well as an extensive exploration of the gray literature sources, including WorldCat, The New York Academy of Medicine Library, and Trip Database, following the established PRISMA protocol. Keywords such as tooth, dentin, grinder, and autograft guided the search, with a focus on a standardized procedure involving dentin grinders within laboratory, experimental, and clinical settings. Initially, a pool of 1942 articles was identified with 452 duplicates removed. An additional 1474 articles were excluded for not aligning with the predefined topics, and three more were excluded due to the unavailability of the full text. Ultimately, 13 articles met the strict inclusion criteria and were included in the review. The chemical composition of the dentin particles was similar to natural bone in terms of oxygen, carbon, calcium, phosphorus, sodium, and magnesium content, as well as in terms of the Ca/P ratio. In addition, the dentin also contained amide I and amide II structures, as well as aliphatic and hydroxyl functional groups. The chemically treated dentin was free of microorganisms. The dentin had characteristic tubules that opened after chemical treatment. At the cellular level, dentin released bone morphogenetic protein 2, induced significant cell growth, and stimulated the reorganization of the fibroblast cytoskeleton. Most clinical studies have focused on alveolar bone regeneration. After the transplantation of demineralized dentin particles, studies have observed new bone formation, a reduction in residual bone, and an increase in connective tissue. Clinical reports consistently indicate uncomplicated healing and recovery post-transplantation. However, there is a notable gap in the evidence concerning complication rates, patient-reported outcomes, and the presence of pro-inflammatory factors. In conclusion, dentin biomaterial emerges as a versatile bone substitute, demonstrating high biocompatibility and ease of acquisition. The preservation of its internal structure containing organic matter and growth factors enhances its potential for effective bone regeneration. Particularly, in dental surgery, dentin-derived materials present a promising alternative to traditional autologous bone autografts, offering the potential to reduce patient morbidity and treatment costs.