Round Particles Research Articles

Bioactivity properties of hydroxyapatite/clay nanocomposites

The need for bioactive and non-toxic biomaterials is on a high demand in tissue engineering applications nowadays. Hydroxyapatite (HAp) is the chief constituent of teeth and bones in mammas. One of the major challenges with the use of HAp in engineering application is its brittleness and to overcome this, it’s important to react it with a material that can enhanced it’s fragility. To this end, HAp and HAp/clay nanocomposites were developed via wet chemical process to mimic natural HAp and to equally confer special properties such as mechanical properties, high surface area, crystallinity, high porosity, and biocompatibility on the biomaterial. The functional groups properties of the as-prepared nanocomposites analyzed by FT-IR showed that the HAp and clay posed reactive centers such as Al–Al–OH, Si–Si–OH, Si–O, PO43−, –OH, and Si–O–Al. The XRD results confirmed the formation of HAp/clay nanocomposite, while SEM and TEM images showed the morphologies of the prepared nanocomposites to be round shape particles. Besides, EDX result revealed the Ca/P ratio of HAp and HAp-C to be lower than that of stoichiometric ratio (1.67) which implies the presence of K, Na, Ca, Mg, Si and Al in the HAp/clay nanocomposite. The mechanical properties of the apatite were greatly enhanced by the addition of clay. The physiological behaviour of the fabricated apatite composites in saline solution showed steady increase in the values of the saline pH of the various biomolecules until day 5 and became fairly constant at day 7 with pH range of 7.30–7.38. Though the saline solution was acidic at the beginning due to dissolved carbon dioxide, the pH of the saline solution containing the nanocomposites gradually became neutral and fairly alkaline over time as a result of the presence of Lewis basis structures in the composites which helps in neutralizing the acidic solution. Furthermore, proliferation of apatites particles onto the surface of the nanocomposites was observed after treatment with simulated body fluids (SBF) media for 7 days. Thus, HAp/clay nanocomposites can be useful biomaterials in bone tissue engineering.

Membrane-derived particles shed by PSMA-positive cells function as pro-angiogenic stimuli in tumors

Cell membrane-derived particles (Mp) are rounded membrane-enclosed particles that are shed from tumor cells. Mp are formed from tumor membranes and are capable of tumor targeting and immunotherapeutic agents because they share membrane homology with parental cells; thus, they are under consideration as a drug delivery vehicle. Prostate-specific membrane antigen (PSMA), a transmembrane glycoprotein with enzymatic functionality, is highly expressed in Mp and extracellular vesicles (EV) from prostate cancer (PCa) with poor clinical prognosis. Although PSMA expression was previously shown in EV and Mp isolated from cell lines and from the blood of patients with high-grade PCa, no pathophysiological effects have been linked to PCa-derived Mp. Here, we compared Mp from PSMA-expressing (PSMA-Mp) and PSMA-non-expressing (WT-Mp) cells side by side in vitro and in vivo. PSMA-Mp can transfer PSMA and new phenotypic characteristics to the tumor microenvironment. The consequence of PSMA transfer to cells and increased secretion of vascular endothelial growth factor-A (VEGF-A), pro-angiogenic and pro-lymphangiogenic mediators, with increased 4E binding protein 1 (4EBP-1) phosphorylation.

Identifying the features of structural and phase transformations during the processing of oxide waste from the production of high-speed steel

Peculiarities of phase and structural transformations during the carbon-thermal recovery of high-speed steel slag with the production of an alloying additive were investigated. This is necessary to determine the technological indicators that allow reducing the loss of high-value elements during the production and use of the alloying additive. A gradual change in the degree of scale reduction from 32 % to 69 % and 77 % led to an increase in the appearance of the solid solution of alloying elements and carbon in the α-Fe lattice with respect to FeWO4 and Fe3O4. Along with this, Fe3C, FeW3C, WC, VC, V2C, and Cr3C2 were manifested. At the same time, the formation of polyhedral and rounded particles of different chemical composition and the formation of a spongy microstructure was observed. It was determined that the most acceptable degree of recovery is 77 %. At the same time, the degree of reduction of 69 % is also sufficient since due to the residual carbon in the form of carbides, an increased reduction capacity is ensured with additional reduction of the oxide component in the liquid metal during alloying. The spongy microstructure provides relatively fast dissolution compared to standard ferroalloys, which causes a reduction in the total melting time while reducing the resources spent. No phases and compounds characterized by an increased tendency to sublimation were detected in the obtained alloying additive. That is, there is no need to provide additional conditions that prevent the loss of high-value elements during evaporation with the gas phase, which causes an increase in the degree of extraction of alloying elements. The indicators of the obtained alloying additive make it possible to melt alloyed steel in an electric arc furnace with respect to brands whose composition does not have strict restrictions on carbon, while replacing a part of standard ferroalloys.

Mineralized Microgels via Electrohydrodynamic Atomization: Optimization and In Vitro Model for Dentin-Pulp Complex.

There is growing interest in the use of micro-sized hydrogels, including bioactive signals, as efficient platforms for tissue regeneration because they are able to mimic cell niche structure and selected functionalities. Herein, it is proposed to optimize bioactive composite microgels via electrohydrodynamic atomization (EHDA) to regenerate the dentin-pulp complex. The addition of disodium phosphate (Na2HPO4) salts as mineral precursors triggered an in situ reaction with divalent ions in solution, thus promoting the encapsulation of different amounts of apatite-like phases. Morphological analysis via image analysis of optical images confirmed a narrow distribution of perfectly rounded particles, with an average diameter ranging from 223 ± 18 μm to 502 ± 64 μm as a function of mineral content and process parameters used. FTIR, TEM, and EDAX analyses confirmed the formation of calcium phosphates with a characteristic Ca/P ratio close to 1.67 and a needle-like crystal shape. In vitro studies-using dental pulp stem cells (DPSCs) in crown sections of natural teeth slices-showed an increase in cell viability until 14 days, recording a decay of proliferation at 21 days, independent on the mineral amount, suggesting that differentiation is started, as confirmed by the increase of ALP activity at 14 days. In this view, mineralized microgels could be successfully used to support in vitro osteogenesis, working as an interesting model to study dental tissue regeneration.

A study of different grinding aids for low-energy cement clinker production

Cement production requires significant energy, and entails high costs and CO2 emissions. This is because the clinker requires very fine grinding. Grinding aids can improve production and fineness and decrease energy consumption by reducing the agglomeration of particles and protecting the balls and liners in the mill. In this study we compare the effects of three different grinding aids on clinker grinding using a ball mill. A commercial grinding additive, triethanolamine (TEA), and two industrial grinding aids (GAA079 and GAA088) were compared by ball milling tests, with additions of 0.05, 0.25, 0.50 and 1.00 wt%. The industrial grinding aids were characterized using gas chromatography-mass spectrometry (GC-MS). Particle size and morphological analyses were performed using SEM and XRD. The best results were obtained with 0.25% GAA088, which has a higher active component of diethanolamine isopropanolamine (DEIPA) than TEA. The unique combination of TEA and DEIPA in GAA088 enhances grinding efficiency and significantly improves the particle size distribution compared to TEA alone.. The grinding aids produced smooth rounded particles, which have a smaller specific surface area, enhancing the quality of the cement. XRD showed no significant structural distortion with or without grinding aids, and it was also found that the grinding aids helped decrease ball coating during grinding. The use of grinding aids can significantly improve clinker production and fineness while decreasing energy consumption, which can help reduce the costs and CO2 emissions associated with cement production.

Seismic isolation effect of unconnected piles-caisson foundation: Large-scale shake table tests

The seismic response and isolation mechanism of a new unconnected pile-caisson foundation (UPCF) suitable for supporting deep-water large-span bridges under seismic loading were investigated by large shaking table tests. Five scaled models were constructed utilizing different cushion material (aggregate), cushion thickness and piles configuration. Each model was tested under 18 different seismic loading conditions. The tests observations were analyzed to evaluate the seismic response characteristics and isolation mechanism of UPCF. The maximum displacement of UPCF and the peak acceleration of the input ground motion were linearly related. Under strong ground motions, the foundation soil and cushion displayed a significant softening behavior manifested in reduced natural frequencies and prolonged periods, which resulted in lower acceleration amplification. However, the stiffnesses of soil and cushion were largely restored after the ground shaking ended. The cushion model with larger aggregate particles performed better in terms of the caisson residual displacement and displacement restoration rate of the caisson. It was found that the UPCF constructed with a thin cushion layer comprised of large, rounded aggregate particles exhibited acceptable seismic isolation effect and reduced the peak seismic acceleration by up to 26.7%. It was also observed that the front and middle piles experienced larger loads, and accordingly, their peak moment envelopes were greater and the location of peak moment was shallower.

Impact of particle elongation on the behavior of round and angular granular media: Consequences of particle rotation and force chain development

We developed a 2D discrete element model to simulate shearing response of elongated round and angular particles. Model was calibrated and validated by comparing numerical results with corresponding biaxial shearing tests on circular (round) and hexagonal (angular) rods at microscopic and macroscopic scales. Then, the systematic effect of particles aspect ratio was investigated on quasi-static shearing response of round and angular granular materials. Macroscopically, we observed a nonlinear tendency wherein as the aspect ratio decreased from 1, the critical state stress ratio initially increased, reaching a maximum, followed by a decreasing trend. This effect was more prominent in round samples. Microscopically, decreasing the aspect ratio from 1 reduced particle rotations and increased the mean coordination number. Elongated particles exhibited significant contact anisotropy, forming irregular force chains, facilitating interparticle sliding, and reducing overall strength. Additionally, we explored the impact of the interparticle friction coefficient. A high value of interparticle friction coefficient led to a monotonically increasing strength with elongation, underscoring the importance of accurately calibrating microscopic friction coefficients.

Widespread occurrence of Tilapia parvovirus in farmed Nile tilapia Oreochromis niloticus from India.

Tilapia parvovirus (TiPV) has been associated with heavy mortalities in tilapia as a single infection or in co-infection with Tilapia lake virus (TiLV). In this study, TiPV was detected in farmed Nile tilapia, Oreochromis niloticus, from two geographical regions of India, Maharashtra and Uttar Pradesh. TiPV-specific polymerase chain reaction (PCR) reported earlier was used in the screening. Tilapia collected from Maharashtra showed characteristic clinical signs, and TiPV was detected along with TiLV and/or Aeromonas spp. However, fish from Uttar Pradesh were apparently healthy and only TiPV could be detected in these samples. A high prevalence of TiPV was recorded from both the geographical locations, Maharashtra and Uttar Pradesh (59.6% and 95.0% respectively). The virus could be detected in tissues such as the spleen, liver, kidney, brain and mucus. The spleen appeared to be the best tissue for detecting TiPV in apparently healthy tilapia. The presence of TiPV was further confirmed through sequencing the PCR products, isolation of the virus in the cell line and electron microscopy. Sequences of the NS1 gene of the two TiPV isolates showed similarity to the earlier reported TiPV isolates. The virus could be successfully propagated in O. niloticus Liver (OnL) cell line, and cytopathic effect was observed as early as 3 days post-infection. Furthermore, the presence of non-enveloped icosahedral to round virus particles measuring about 26-35 nm could be demonstrated in the cytoplasm and nucleus of infected OnL cells in transmission electron microscopy. With this confirmation of the presence of the virus, India is the third country to report TiPV after China and Thailand. The detection of TiPV in co-infection cases with TiLV and in apparently healthy Nile tilapia suggests its wide distribution and potential synergistic effect in co-infection cases. Therefore, this emerging virus needs holistic attention to understand its virulence, host-specificity and epidemiological risk factors.

Effects of particle angularity on the bulk-characteristics of granular assemblies under plane strain condition

We investigate the influence of particle angularity on the stress–strain behaviour, rotation and micromechanics of granular assemblies under plane strain condition. Granular particles are modelled as regular polygons and numerical biaxial compression tests have been performed using the discrete element method. The packings consist of regular polygons with increasing corner number ranging from 5 to 64. The packings are analysed in the critical state in terms of their shear strength, bulk friction angle and porosity, as well as their cumulative rotation and contact characteristics with respect to varying particle angularity. We find that packings of more angular particles are looser but have higher shear strength, while packings of more rounded particles are denser, but are less resistant to shear. We further show that packings of angular particles are more resistant to reorganization by rotation, and that the mean rotation magnitude saturates at a constant value with increasing roundness. Lastly, we find that packings of more angular particles tend to have less contacts with higher normal and tangential forces when compared with packings of more rounded particles.

CoS2:Ni17S18:Al2S3 thin film as supercapacitor electrode for astounding energy storage and explicit photocatalyst for pollutants degradation

The ternary metal sulfide CoS2:Ni17S18:Al2S3 thin films were created in the presence of diethyldithiocarbamate as a sulfur source, pursued by physical vapour deposition. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, UV-visible spectrophotometer, and Fourier transform infrared spectroscopy were used to identify and characterize the synthesised substances. The ternary metal sulfide had a mean crystallite size of 37.8 nm on the nanoscale. SEM revealed spherical particles with rounded edges particles. XPS presented Al 2p, Co 2p, Ni 2p and S 2p core level peaks of the elements. The ternary metal sulfide had a band gap energy of 3.49 eV. The phenomenal storage technology potential of the thin film was evaluated using cyclic voltammetry that revealed an astounding supercapacitance of 515 F g−1, demonstrating the material’s effectiveness. Voltammetric findings show the cycling stability of the nanoparticle thin film. Moreover, the photocatalytic degradation of contaminants such as methylene blue dye, pesticide zoxamide, and phenol was probed, with such a spectacular degradation rate constant of 4.11 × 10−2 min−1 with 91.5% degradation achieved for pesticide.

Properties and Lightfastness of Natural and Artificial Azurite Used As Painting Pigment

Azurite is an inorganic pigment commonly used in traditional painting arts and even today. This pigment has two types: natural azurite and synthetic artificial azurite, called blue verditer or blue bice. Because they have the same structure and similar appearance they are difficult to distinguish. The purpose of this study is to compare these two types pigments, focusing on material properties and accelerated weathering behavior. Natural azurite consist of copper carbonate and mineral compounds like quartz, kaolinite. On the other hand, artificial azurites are synthesized using azurite and calcite. As a result of thermal analysis, unlike natural azurite, the calcite in artificial azurite resulted in weight loss at three temperatures, at approximately 350 ℃, 650 ℃, and 840 ℃. According to the microscope analysis results, natural azurites have clearly blue angular particles with sharp edges, produced by crushing. Artificial azurite showed spherules and aggregates with tiny rounded or fibrous particles. After accelerated weathering tests, the natural azurites had no change in color, particle shape or original components, but the artificial azurites noticeably changed color and shape. The color changes of artificial azurites occurred due to the growth of calcite crystallite, a slight new product formation, and change in particle shape. Even though natural azurites are more expensive pigments, they provide superior color durability and particle shape stability compared to artificial azurites.

Enhancing performance of all-solid-state battery by establishment of interconnected Li7La3Zr2O12 network in graphite composite anode

Garnet-type Li7La3Zr2O12 (LLZO) solid electrolytes are synthesized with interconnected and larger rounded particle morphologies using a cellulose template method and conventional solid-state reaction, respectively. The synthesized LLZOs are optimized and used as a solid electrolyte in a natural graphite (NG)-based composite anode in an all-solid-state lithium battery. For the LLZO with the interconnected particle morphology, the optimum heat-treatment temperature (900 °C) and LLZO content (30 wt%) are determined to result in higher ionic conductivity. That is, higher dispersion or good distribution of the interconnected LLZO (width of 1 μm or less) within the composite anode enables easier ionic conduction of the interconnected LLZO. The NG-based composite anode filled with interconnected LLZO shows effective improvement due to a well-controlled inner percolation structure, resulting in improved cycle stability and enhanced high-rate capability, compared with the composite anode embedded with conventional spherical-type LLZO particles.

Effect of different boron sources on the copper borates in solid-state synthesis

Abstract The copper borate of CuB2O4 in tetragonal form was successfully synthesized as a single-phase by using a solid-state method without using any modifying agent. For the designed experimental procedure, the optimized reaction conditions were estimated as a reaction temperature of 950 °C, reaction time of 240 min, argon atmosphere and Cu:B ratio of 1:5. The possible reaction mechanism estimated for both boron sources of boric acid and boron oxide. In both sets, the lower ratios of Cu:B supported CuB2O4 formation. In the use of boric acid as a boron source, higher reaction yield percentages (98 %) and lower particle sizes were determined. The micron-scale rounded particles were observed in morphological analyses and the particles were shaped in homogeneity in the use of boron oxide as a boron source. The specific FT-IR peaks were observed at the band values of 1190, 1035, 988, 945, 890, 695, 631, 540 and 479 cm−1. The experimental results highlighted the probable use of solid-state in the copper borate synthesis.

Microstructure-based simulation on the mechanical behavior of particle reinforced metal matrix composites with varying particle characteristics

The mechanical performance of metal matrix composites strengthened with particles is predominantly contingent upon the attributes of the incorporated particles. Attaining the optimal particle size, morphology, and interfacial bonding within the composites is paramount for improving the comprehensive properties. In this study, an experimentally congruent model was devised to validate the feasibility of the model predicated on the actual microstructure of the composite. The modeling procedure encapsulated matrix and particle failure, as well as surface-based cohesive damage at the interface, to precisely portray the mechanism of action for the particle characteristics. Additionally, the mechanical behavior and failure evolution mechanism of the composites were simulated by manipulating the pertinent particle factors, including size distribution, interfacial strength, and morphology. The findings demonstrated that an appropriate size distribution between particles and more rounded particles can mitigate stress and strain concentration within the matrix interstitial to particles, resulting in a considerable enhancement in the mechanical performance of the composites. As the interfacial strength decreases, the initial failure progression of the composite shifts from initial cracking within the matrix induced by stress-strain concentration to interfacial failure caused by interfacial debonding, ultimately accelerating the failure of composite. This research will bolster the comprehension of the correlations between microstructural features and mechanical performance in metal matrix composites strengthened with particles, providing an innovative simulation-assisted experimental approach for the rapid development and preparation of novel metal matrix composites.

Study of Ni/Y2O3/Polylactic Acid Composite.

This study demonstrates the successful synthesis of Ni/Y2O3 nanocomposite particles through the application of ultrasound-assisted precipitation using the ultrasonic spray pyrolysis technique. They were collected in a water suspension with polyvinylpyrrolidone (PVP) as the stabiliser. The presence of the Y2O3 core and Ni shell was confirmed with transmission electron microscopy (TEM) and with electron diffraction. The TEM observations revealed the formation of round particles with an average diameter of 466 nm, while the lattice parameter on the Ni particle's surface was measured to be 0.343 nm. The Ni/Y2O3 nanocomposite particle suspensions were lyophilized, to obtain a dried material that was suitable for embedding into a polylactic acid (PLA) matrix. The resulting PLA/Ni/Y2O3 composite material was extruded, and the injection was moulded successfully. Flexural testing of PLA/Ni/Y2O3 showed a slight average decrease (8.55%) in flexural strength and a small decrease from 3.7 to 3.3% strain at the break, when compared to the base PLA. These findings demonstrate the potential for utilising Ni/Y2O3 nanocomposite particles in injection moulding applications and warrant further exploration of their properties and new applications in various fields.

Characterization of Magnetic Nanoparticles from the Shells of Freshwater Mussel L. fortunei and Marine Mussel P. perna

Magnetite (Fe3O4) nanoparticles were extracted from the shells of freshwater Limnoperna fortunei (Dunker 1857) and marine Perna perna (Linnaeus 1758) mussels, followed by full physical and chemical characterization using ICP-OES, UV–Vis, EDX, Raman, and XRD spectroscopy, VSM magnetometry, and SEM and TEM techniques. Considering their spatial distribution, the ferrimagnetic particles in the shells had low concentration and presented superparamagnetic behavior characteristics of materials of nanometric size. Transmission electron microscopy (TEM, especially HRTEM) indicated round magnetic particles around 100 nm in size, which were found to be aggregates of nanoparticles about 5 nm in size. The TEM data indicated no iron oxide particles at the periostracum layer. Nevertheless, roughly round iron (hydr)oxide nanoparticle aggregates were found in the nacre, namely, the aragonite layer. As the aragonite layer is responsible for more than 97% of the shell of L. fortunei and considering the estimated size of the magnetic nanoparticles, we infer that these particles may be distributed homogeneously throughout the shell.

Phase variation and mechanical properties of waste calcium carbonate to substitute quartz in composite slab production

AbstractOwing to the fast‐emerging nature and rapid advancements in the construction industry, huge volumes of marble dust (MD) are generated as reject during slab cutting in marble processing, causing significant environmental hazards. Nowadays, quartz composite slabs have increasingly been preferred in building works due to their excellent hygienic property and mechanical strength. Composite slab is produced using micronized quartz as filler, the grinding of which is an energy‐intensive process. Substitution of micronized quartz with MD at different percentages was investigated in natural form and after roasting. Natural MD offered appreciable physical properties closer to those of a quartz composite slab. Physical properties slightly retrograded by quartz supplementation in the raw form. Roasting the filler led to the formation of rounded Ca–silicate. Wollastonite was the first phase formed after sintering at the lowest MD percentage and shortest roasting times. Larnite became dominating phase first by increasing MD percentage and roasting time, and then calcio‐olivine formed. Physical characterization test results demonstrated that hardnesses of new phase and particle shape were the key parameters that improved slabs’ mechanical properties of. Hard rounded larnite particles improved mechanical behavior of slabs having the synergic effect of quartz, whereas wollastonite did not show a significant effect.

Pore-scale analysis of hydrate saturation on the physical parameters of hydrate-bearing sediment with different particle shapes

Methane hydrate is the most potential novel energy source with huge reserves to be developed, and is the priority of countries' future energy development strategies. Evaluating the basic physical characteristics of hydrate reservoirs, especially permeability, thermal, and electrical conductivity, is essential for clarifying the main controlling factors of physical characteristics and formulating a reasonable development strategy. Accordingly, 16 cementing hydrate-bearing models with different particle shapes were constructed account of a new three dimensions morphologic modeling algorithm for hydrate in this study. Based on the above models, the evolution of pore space distribution and basic physical properties of hydrate-bearing sediments (HBS) have been analyzed via pore network modeling (PNM) and finite volume method (FVM). The results show that (1) the quantity of pores and throats of HBS with round particles is higher, and the average radius is smaller than those of HBS with irregular particles, (2) increasing hydrate saturation leads to a decrease in absolute permeability, with a more rapid decrease in permeability for HBS with irregular particles, (3) the thermal conductivity of HBS with round particles exceeds those of HBS with irregular particles, and the their curves remain parallel with increasing hydrate saturation, (4) the resistivity index of HBS with round particles increases faster as hydrate forms, and the conductivity is always smaller than those of HBS with irregular particles.

Rücktitelbild: Coronaviruses Use ACE2 Monomers as Entry‐Receptors (Angew. Chem. 30/2023)

A coronavirus (round particles) carrying trimeric spike proteins (green) infects a host cell that expresses monomeric ACE2 receptors (magenta). The low density of ACE2 receptors on the cell membrane demonstrates that on average only one spike protein per virus particle can bind to an ACE2 receptor simultaneously, which provides SARS-COV-2 a high infectivity. After binding, the membranes fuse and viral components are released into the cell, as reported by Gerti Beliu, Markus Sauer et al. in their Research Article (e202300821).

Back Cover: Coronaviruses Use ACE2 Monomers as Entry‐Receptors (Angew. Chem. Int. Ed. 30/2023)

A coronavirus (round particles) carrying trimeric spike proteins (green) infects a host cell that expresses monomeric ACE2 receptors (magenta). The low density of ACE2 receptors on the cell membrane demonstrates that on average only one spike protein per virus particle can bind to an ACE2 receptor simultaneously, which provides SARS-COV-2 a high infectivity. After binding, the membranes fuse and viral components are released into the cell, as reported by Gerti Beliu, Markus Sauer et al. in their Research Article (e202300821).