Entry Of Particles Research Articles

Transcription- and Replication-Competent Virus-like Particle Systems for Marburg Virus.

Here, we describe the transcription- and replication-competent virus-like particle (trVLP) system for Marburg virus (MARV), which recapitulates transcription and replication of the viral genome in addition to viral particle assembly, egress, and entry. This protocol includes instructions for transfections for producer and acceptor cells and the use of trVLPs for infection.

Geoenvironmental and Health Indices to Assess the Hazardousness of Heavy Metals in Urban Dust in Schoolyards in Murcia, Spain.

The aim of this study was to evaluate the possible contamination of urban dust in the schoolyards of 27 schools in an urban area of the city of Murcia (SE Spain). The color and degree of magnetism, as well as the heavy metal content (Cd, Cu, Cr, Ni, Pb, and Zn), were determined to establish the absence or the degree of contamination, if present, using environmental and health indices. It was established that the concentrations of heavy metals in the dust samples followed the order Zn (454 mg kg-1) > Cu (77 mg kg-1) > Cr (68 mg kg-1) > Pb (56 mg kg-1) > Ni (19 mg kg-1) > Cd (0.4 mg kg-1). Dark-colored dust showed the highest concentrations of contaminants associated with medium or high magnetism. An analysis of the magnetic and non-magnetic fractions indicated the highest concentrations of all heavy metals in the magnetic fraction. According to the geoenvironmental indices used, the ecological risk in these schoolyards is moderate overall. Based on the health indices, ingestion is the main route of entry of dust particles into the body, which poses the main health risk for adults and children for all heavy metals. Regarding the hazard index (HI) for all elements and the cancer risk (CR) for children and adults, the results indicate that there is no health risk.

Circuit Modeling of the Impact of Heavy Charged Particles on Transient Processes in Bipolar Analog Microcircuits

One of the factors causing the failure of spacecraft integrated circuits is exposure to heavy charged particles. The entry of heavy charged particles into electronic devices leads to the appearance of single event transients (short current pulses), which in analog microcircuits manifest themselves in distortion of the output signal shape, and in digital microcircuits can cause a single event upset. The article discusses a technique for circuit mode-ling of the effect of heavy charged particles on bipolar analog microcircuits, including the developed equivalent electrical circuit of a bipolar transistor for LTSpice and the procedure for modeling transient processes. Despite the simplifications adopted, namely: failure to take into account the dependence of the duration of the rise and fall of the current pulse generated by a charged particle on the parameters of the transistor structure, the assumption that the entire charge is generated in the active base and the space charge regions of the emitter and collector junctions, an equivalent circuit has been developed made it possible to determine that the shape of the collector current pulse for circuit with a common emitter when exposed to a heavy charged particle is determined by the speed of the transistor and its operating mode. Using the developed methodology, the “critical” transistors of the two studied analog microcircuits were determined, and the need to bypass the current-setting resistors with a small capacitor was justified.

Design and Test of Molecules that Interfere with the Recognition Mechanisms between the SARS-CoV-2 Spike Protein and Its Host Cell Receptors.

The disruptive impact of the COVID-19 pandemic has led the scientific community to undertake an unprecedented effort to characterize viral infection mechanisms. Among these, interactions between the viral glycosylated Spike and the human receptors ACE2 and TMPRSS2 are key to allowing virus invasion. Here, we report and test a fully rational methodology to design molecules that are capable of perturbing the interactions between these critical players in SARS-CoV-2 pathogenicity. To this end, we computationally identify substructures on the fully glycosylated Spike protein that are not intramolecularly optimized and are thus prone to being stabilized by forming complexes with ACE2 and TMPRSS2. With the aim of competing with the Spike-mediated cell entry mechanisms, we have engineered the predicted putative interaction regions in the form of peptide mimics that could compete with Spike for interaction with ACE2 and/or TMPRSS2. Experimental models of viral entry demonstrate that the designed molecules are able to interfere with viral entry into ACE2/TMPRSS2 expressing cells, while they have no effects on the entry of control viral particles that do not harbor the Spike protein or on the entry of Spike-presenting viral particles into cells that do not display its receptors on their surface.

Accumulation modes and effects of differentially charged polystyrene nano/microplastics in water spinach (Ipomoea aquatica F.)

There is widespread concern about the risk of nano/microplastics (N/MPs) entering the food chain through higher plants. However, the primary factors that influence the absorption of N/MPs by higher plants remain largely unclear. This study examined the impact of Europium-doped N/MPs with different particle sizes and surface charges by water spinach (Ipomoea aquatica F.) to address this knowledge gap. N/MPs were visualized and quantitatively analyzed using laser confocal microscopy, scanning electron microscopy, and inductively coupled plasma-mass spectrometry. N/MPs with different surface charges were absorbed by the roots, with the apoplastic pathway as the major route of transport. After 28 days of exposure to 50 mg L−1 N/MPs, N/MPs-COOH caused the highest levels of oxidative stress and damage to the roots. The plants accumulated NPs-COOH the most (average 1640.16 mg L−1), while they accumulated NPs-NH2 the least (average 253.70 mg L−1). Particle size was the main factor influencing the translocation of N/MPs from the root to the stem, while the Zeta potential mainly influenced particle entry into the roots from the hydroponic solution as well as stem-to-leaf translocation. Different charged N/MPs induced osmotic stress in the roots. A small amount of N/MPs in the leaves significantly stimulated the production of chlorophyll, while excessive N/MPs significantly reduced its content. These results provide new insights into the mechanism of interaction between N/MPs and plants.

Modeling the critical rotation speed of a bladed rotor with bent blades in a circulation mixer of feed mixtures

The purpose of the research is to substantiate the critical rotation speed of a rotor with bent blades based on force analysis and modeling the movement of mixture particles in a horizontal loader of a circulation mixer. The research method[1]ology included the substantiation of the highest rotation frequency of the loader blade rotor based on a force analysis of moving particles of forces when they were moved by the bent blades of the loader and compliance with the conditions for the entry of flying particles into the tray. The numerical analysis performed on the basis of the obtained expressions using the Mathcad mathematical package made it possible to establish the critical values of the rotation speed of the rotor-loader with bent blades based on the condition of the material coming off the blade and the condition of the flight of particles from the blade into the receiving tray. With radial blades, the limitation is the entry of particles into the receiving tray at a critical frequency of 43 min-1 , then for a blade bend of 30° – about 60 min-1 , for a blade bend of 45° – about 70 min-1, for a blade bend of 60° – about 80 min-1. The lowest critical values of the rotor-loader rotation frequency from the condition of particle movement along the blade correspond to the blade bend angle of 27–60° and are determined by the friction coefficient of the material, amounting to 83–78 min-1. With an increase in material friction, the critical values of the rotor rotation speed from the condition of material coming off the blade decrease slightly, and the bend angle for the rotation speed extremum increases. The highest rotation speed of the rotor - loader with a radius of 0.12 m is limited to 78 min-1 at a blade bending angle of the order of 30–60°, determined by the friction of the material on the blade.

Numerical analysis of the mechanics of foreign particle entry on automotive turbocharger compressor blades

Automotive turbochargers, essential for enhancing intake air pressure and boosting torque in internal combustion engines, operate at exceptionally high rotational speeds of approximately 100,000 to 300,000 rpm. Despite the implementation of dual or triple air filtration systems to filter contaminants, neglected maintenance can lead to clogged filters, resulting in the ingestion of metallic filter mesh, and other small-sized objects from filter indicators, washers, and plastic components into the turbocharger assembly. The current study explores the impact of foreign particles on the mechanics of turbocompressor impeller blades in automotive turbochargers through a computational approach. A finite element model of the turbocompressor wheel was developed with suitable boundary conditions for the turbocompressor and the foreign particle. A Design of Experiments (DoE) approach was employed using a Taguchi L12 orthogonal array to optimize the multiple parameters during the foreign particle impact. The study considered two geometric shapes of the foreign particle (conical with unit aspect ratio and hemispherical), two sizes, and two rotational speeds ranging from 150,000 to 250,000 rpm. ANSYS Explicit Dynamics® software was utilized for the numerical simulations to simulate the mechanics of foreign particle entry and the resulting damage on compressor blades.

Positively Charged Microparticle in Plasma with High-Energy Electron Beam

The processes of recharging, heating and evaporation of a positively charged microparticle (MP) introduced into the plasma with an injected high-energy electron beam are considered. It is assumed that the MP is charged outside the plasma and then introduced into the plasma by an accelerating field, where plasma and beam electrons hitting the MP heat and evaporate it. In addition to introducing the MP into the plasma, the positive MP charge provides an additional source of energy needed to heat and evaporate it. Using the OML theory, the system of current and energy balance equations was numerically solved and the conditions, under which the MP is heated to the boiling point of its substance, resulting in its intense evaporation, were determined. The influence of the energy of the electron beam on the process of MP recharging, as well as on the rate of its heating and evaporation, has been studied. An estimate of the particle entry velocity into the plasma has been made; the distances at which its recharging, heating to the boiling point and complete evaporation occur are determined. The work is carried out in order to creating plasma of a given elemental composition.

Electromigration effect of nano-Fe3O4 in concrete under chloride erosion environment

In order to improve the effectiveness of electro-migration repair technology, researchers have introduced new materials to address the adverse effects of electrochemical repair on concrete, such as interface softening in reinforced concrete. In this study, a dispersed solution of nano-Fe3O4 was selected as the anode electrolyte. Concrete specimens were subjected to electric treatment for repair, and the entry of nano particles into the concrete under the action of an external electric field was investigated. The microstructure and mechanical properties of the repaired concrete material were analyzed using techniques such as potentiodynamic polarization curve, chemical titration, scanning electron microscopy, energy spectrum analysis, mercury intrusion porosimetry, and pull-out test. The results showed that after 15 days of electrochemical nano-repair, the passivation film on the steel reinforcement was repaired, resulting in a 57 % reduction in corrosion rate and prevention of further chloride ingress, thus improving the corrosion resistance of the reinforcement. Furthermore, the electrochemical nano-repair did not affect the outward migration of chloride ions from the concrete, with a chloride removal efficiency as high as 72.6 %. When the treatment duration was 15 days and the current density was 3 A/m2, the bond strength exhibited the greatest improvement, with an increase of 99.15 %. Compared to electrochemical chloride removal, the electrochemical nano-repair reduced the porosity in the middle and inner layers by 17.8 % and 14.8 %, respectively. Microstructural analysis revealed that the electromigrated nano-Fe3O4 particles were uniformly dispersed within the concrete, replacing harmful byproducts and filling the pores.

Cellular uptake of active nonspherical nanoparticles

Due to the potential applications in biomedical engineering, it becomes more and more important to understand the process of engulfment and internalization of nanoparticles (NPs) by cell membranes. Despite the fact that the interaction between cell membranes and passive particles has been widely studied, the interaction between cell membranes and self-propelled nonspherical NPs remains to be elucidated. Here, we present a theoretical model to systematically investigate the influence of the active force, aspect ratio of NPs, particle size, and membrane properties (adhesion energy density and membrane tension) on the cellular uptake of a nonspherical nanoparticle. It is found that the active force generated by an NP can trigger a type of first-order wrapping transition from a small partial wrapping state to a large one. In addition, the phase diagram in the force-aspect ratio (particle size, adhesion energy density, and membrane tension) space displays more complex behaviors compared with that for the passive wrapping mediated merely by adhesion. These results may provide useful guidance to the study of activity-driven cellular entry of active particles into cells.

A mathematical framework for analysing particle flow in a network with multiple pools.

In many real-world systems, the entry rate of particles into a lane is affected by the occupancy of nearby pools. For instance, in biological networks, the concentration of molecules on the side of a membrane affects the entry of particles through the membrane. To understand the behaviour of such networks, we develop a network model of ribosome flow models (RFMs) having multiple pools where each RFM captures the dynamics of particle flow in a lane and competes for the finite resources present at the nearby pool. We study a ribosome flow model network with two pools (RFMNTP) and show that the network always admits a steady state. We then analyse the behaviour of the RFMNTP with respect to modifying the transition rate through a theoretical framework. Simulations of the RFMNTP demonstrate a counterintuitive result. For example, increasing any of the transition rates in the presence of a slow site in an RFM can increase the output rate of some RFMs and decrease the output rate of the other RFMs simultaneously. This suggests that the role of local sharing of particles incorporated is non-trivial. Finally, we illustrate how these results can provide insights into studying a network with multiple pools.

Cellular response of keratinocytes to the entry and accumulation of nanoplastic particles

Plastic accumulation in the environment is rapidly increasing, and nanoplastics (NP), byproducts of environmental weathering of bulk plastic waste, pose a significant public health risk. Particles may enter the human body through many possible routes such as ingestion, inhalation, and skin absorption. However, studies on NP penetration and accumulation in human skin are limited. Loss or reduction of the keratinized skin barrier may enhance the skin penetration of NPs. The present study investigated the entry of NPs into a human skin system modeling skin with compromised barrier functions and cellular responses to the intracellular accumulations of NPs. Two in vitro models were employed to simulate human skin lacking keratinized barriers. The first model was an ex vivo human skin culture with the keratinized dermal layer (stratum corneum) removed. The second model was a 3D keratinocyte/dermal fibroblast cell co-culture model with stratified keratinocytes on the top and a monolayer of skin fibroblast cells co-cultured at the bottom. The penetration and accumulation of the NPs in different cell types were observed using fluorescent microscopy, confocal microscopy, and cryogenic electron microscopy (cryo-EM). The cellular responses of keratinocytes and dermal fibroblast cells to stress induced by NPs stress were measured. The genetic regulatory pathway of keratinocytes to the intracellular NPs was identified using transcript analyses and KEGG pathway analysis. The cellular uptake of NPs by skin cells was confirmed by imaging analyses. Transepidermal transport and penetration of NPs through the skin epidermis were observed. According to the gene expression and pathway analyses, an IL-17 signaling pathway was identified as the trigger for cellular responses to internal NP accumulation in the keratinocytes. The transepidermal NPs were also found in co-cultured dermal fibroblast cells and resulted in a large-scale transition from fibroblast cells to myofibroblast cells with enhanced production of α-smooth muscle actin and pro-Collagen Ia. The upregulation of inflammatory factors and cell activation may result in skin inflammation and ultimately trigger immune responses.

Numerical investigation on the effect of feed operating parameters and inlet structure on a cyclone utilizing flow splitting for performance enhancement

The shunting technique is regarded as one of the most crucial approaches for suppressing localized secondary flow within a cyclone. This study employs the Reynolds stress model and discrete phase model to investigate the impact of inlet structure and feed operating parameters on the performance of enhanced cyclone with split flow (ECSF), aiming to further enhance its efficiency. The findings demonstrate that the optimum feed velocity of ECSF is 29 m/s, which surpasses that of Lapple cyclone at 23 m/s. In addition, both a contracting inlet and multiple inlets contribute to enhancing the separation efficiency of ECSF. Specifically, ECSF with a contracting inlet exhibits a total separation efficiency of 86.8% for 2.5 μm particles, representing an improvement of 12.3% compared to ECSF with a straight inlet configuration. The enhancement in separation efficiency achieved through the implementation of the four-inlet design is even more pronounced. The segregated particles are directed into the discharge pipe via either underflow or bypass flow, and the trajectory of particle entry into the discharge pipe is closely associated with their cross-sectional positioning prior to entering the cylinder.

Proximity labeling of host factor ANXA3 in HCV infection reveals a novel LARP1 function in viral entry

Hepatitis C virus (HCV) infection is tightly connected to the lipid metabolism with lipid droplets (LDs) serving as assembly sites for progeny virions. A previous LD proteome analysis identified annexin A3 (ANXA3) as an important HCV host factor that is enriched at LDs in infected cells and required for HCV morphogenesis. To further characterize ANXA3 function in HCV, we performed proximity labeling using ANXA3-BioID2 as bait in HCV-infected cells. Two of the top proteins identified proximal to ANXA3 during HCV infection were the La-related protein 1 (LARP1) and the ADP ribosylation factor-like protein 8B (ARL8B), both of which have been previously described to act in HCV particle production. In follow-up experiments ARL8B functioned as a pro-viral HCV host factor without localizing to LDs and thus likely independent of ANXA3. In contrast, LARP1 interacts with HCV core protein in an RNA-dependent manner and is translocated to LDs by core protein. Knockdown of LARP1 decreased HCV spreading without altering HCV RNA replication or viral titers. Unexpectedly, entry of HCV particles and E1/E2-pseudotyped lentiviral particles was reduced by LARP1 depletion, whereas particle production was not altered. Using a recombinant vesicular stomatitis virus (VSV)ΔG entry assay, we showed that LARP1 depletion also decreased entry of VSV with VSV, MERS, and CHIKV glycoproteins. Therefore, our data expand the role of LARP1 as an HCV host factor that is most prominently involved in the early steps of infection, likely contributing to endocytosis of viral particles through the pleiotropic effect LARP1 has on the cellular translatome.

Occurrence of microplastics in edible tissues of livestock (cow and sheep).

Plastic contamination is widely recognized as a major environmental concern due to the entry of small plastic particles into the food chain, thereby posing potential hazards to human health. However, the current understanding of microplastic (MP; < 5 mm) particles in livestock, which serve as an important food source, is limited. This study aims to investigate the concentration and characteristics of MPs in edible tissues of cow and sheep, namely liver, meat, and tripe, obtained from butcher shops in five areas of Bushehr port, Iran. The mean concentration of MPs in different tissues of cow and sheep were 0.14 and 0.13 items/g, respectively. Among the examined tissues, cow meat exhibited the highest concentration of MPs, with a concentration of 0.19 items/g. Nylon and fiber were identified as the predominant polymer types and shapes of MPs found in cow and sheep tissues, respectively. Furthermore, no statistically significant difference was observed in MP concentration across different tissues of cow and sheep. Significantly, this study highlights the elevated hazards associated with exposure to MPs through the consumption of edible cow and sheep tissues, particularly for children who consume meat. The results underscore the potential transfer of MPs from the environment to livestock bodies through their food, contamination during meat processing, and subsequent health hazards for consumers.

Human induced pluripotent stem cells are resistant to human cytomegalovirus infection primarily at the attachment level due to the reduced expression of cell-surface heparan sulfate.

Numerous factors such as attachment, virus particle entry, transcription, and virus particle egress can affect viral susceptibility. Since 1984, pluripotent cells are known to be CMV resistant; however, the exact mechanism underlying this resistance remains elusive. Some researchers suggest inhibition in the initial phase of HCMV binding, while others have suggested the possibility of a sufficient amount of HCMV entering the cells to establish latency. This study demonstrates that HCMV particles rarely attach to the surfaces of hiPSCs. This is not due to limitations in the electrostatic interactions between the surface of hiPSCs and HCMV particles, but due to HS expression. Therefore, HS expression should be recognized as a key factor in determining the susceptibility of HCMV in congenital infection in vitro and in vivo. In the future, drugs targeting HS may become crucial for the treatment of congenital CMV infections. Thus, further research in this area is warranted.

Adhesive materials in solar-thermal collectors: Results of seven years field exposure and accelerated aging tests used to simulate 25 years of operation

The adhesive joint takes over multiple functions in the solar thermal collector, such as the structural bonding, the absorption of thermal stress of the transparent cover to the collector housing, and the sealing of the collector with respect to humidity, air and particle entry. Thus, it is a central component in a solar thermal collector.The aging effects occurring in solar collectors within the adhesive material are by now not well understood. They are determined primarily by the temperature level in the collector. This temperature level has significantly increased during the last years due to the enhancement of the collector efficiency and the trend towards solar thermal systems with higher solar fractions resulting in an increase in stagnation time and temperature. Furthermore, durability analyses of novel market products are needed, since only little is known about their long-term behavior.The accelerated aging tests described in this article represent the measured load in the solar collector at the component adhesive joint to a calculated corresponding period of 25 years.We found that all test specimens showed a 100 % cohesive fracture pattern after these stress tests. Thus, the adhesion between the transparent cover and the collector housing can be assumed to be ensured using the framework with the load depicted in the defined test cycle over 25 years. Compared to the reference value before aging, the tensile strength values change only marginally after being degraded.The results of the mechanical properties of the small test specimens before and after seven years of exposure in maritime climate were determined and compiled. A nondestructive characterization method at the test specimens with Raman spectroscopy accompanied before the mechanical tensile testing was done.

Understanding of baffle effect of inserting a filter within a tundish via a water model experiment and numerical simulation

The baffle effect of inserting a filter within a tundish was investigated using a combination of water model experiments and numerical simulations. The filter, which is a cost-effective device used to enhance the quality of molten steel by removing inclusions, was studied for its impact on the removal rate of inclusions. In the water model experiments, a scaled-down model of the tundish system was created with a geometric ratio of 1:4. Polyethylene particles of varying sizes were used to simulate the inclusions. Additionally, a three-dimensional numerical model of the water model was developed to validate the experimental findings, provide supplementary data for analysis, and propose an optimized tundish configuration by moving the weir away from the filter by 50, 100, and 150 mm. The flow patterns were also thoroughly examined. The results revealed that the presence of the filter increased the flow resistance within the tundish, leading to changes in the residence time distribution. This resulted in the formation of a ‘dead zone’ with a significantly prolonged residence time. The higher flow resistance hindered the entry and exit of particles from the last chamber of the tundish. As a result, the distribution of particles in the last chamber became more dispersed, reducing the detrimental effects of inclusions in the steel. The removal efficiency of the seven types of particles was improved by 2–7%. Furthermore, by moving the weir away from the filter by 50 mm, the removal ratio could be further increased by approximately 2%.

Polysaccharides derived from Spirulina platensis inhibited Singapore grouper iridovirus by impeding the entry of viral particles

Attributable to the rapid dissemination and high lethality of Singapore grouper iridovirus (SGIV), it has caused significant economic losses for marine fish aquaculture in China and Southeast Asian nations. Hence, there is an urgent need to find antiviral drugs that are both safe and effective. In this study, a novel heteropolysaccharide named Spirulina platensis polysaccharides (SPP) was purified and characterized from S. platensis. The molecular weight of SPP is 276 kDa and it mainly consists of Glc and Rha, followed by minor components such as Gal, Xyl, and Fuc. The backbone of SPP was determined to be →2) –β–Rhap–(1 → 4) –α–Fucp–(1 → [2) –α–Rhap–(1] 2[→6)–α–Glcp–(1] 4[→ 4) –α–Glcp–(1] 8[→ 4) –β–Glcp–(1]2→, with branches of β–Galp, α–Xylp and α–Glcp. SPP significantly inhibited SGIV-induced cytopathic effects (CPEs), viral gene replication and viral protein expression. The antiviral mechanism of SPP was associated with the disruption of SGIV entry to host cells. Furthermore, it was not observed that SPP made statistically significant impact on the expression of interferon-related cytokines. Our results offered novel insights into the potential utilization of spirulina polysaccharides for combating aquatic animal viruses.

HDL mimetics protect Alzheimer’s patients carrying APOE ε4 from SARS-CoV-2 invasion

Patients with Alzheimer’s disease (AD) inheriting Apolipoprotein (APOE) ε4 are susceptible to COVID-19, but the underlying mechanism of how such a neurodegenerative disease promotes respiratory vulnerability to viral infections remains insufficiently understood. The uncovering of genetic basis of COVID-19 outcome holds the potential to establish disease models for therapeutic development. Here, using human iPSC-derived type II alveolar epithelial cells (hAECII) from AD patients with APOE ε4 and healthy individuals, we showed that AECII of AD had a greater level of SARS-CoV-2 invasion but not replication, along with increased expressions of viral receptor and co-receptors, while reduced pulmonary surfactant proteins. Since low serum HDL-C levels have been implicated in the onset of both AD and COVID-19, we further revealed that HDL mimetics, including 4 F dimeric peptide and its phospholipid conjugate pHDL, were effective in protecting AECII bearing APOE ε4 against SARS-CoV-2 invasion. In AD, concomitant with improved AD pathological phenotypes, HDL mimetics specifically restored the defective basal SP-D, a pulmonary innate immune lipoprotein that targets glycans of the spike protein to neutralize invading viruses. Moreover, HDL mimetics demonstrated strong SP-D-independent virucidal effects, which additionally restricted the entry of coronaviral particles into non-AD AECII models and lungs of human ACE2-transgenic mice in response to Alpha and Omicron variants of SARS-CoV-2. Our work offers critical insights into the respiratory sensitivity of AD patients carrying APOE ε4 to viral infection and repurpose HDL-based therapeutics as potential preventive interventions in respiratory viral pandemics.