Particle Analysis Research Articles

Propulsion particle and potential application analysis based on fiber oriented laser propulsion micro-structures

Three kinds of fiber oriented laser propulsion micro-structures (tapered fiber, fiber-capillary, and flat fiber micro-structure) were proposed in this study. The directional of the shock wave generated at the tip of the micro-structure, which can realize the directional propulsion of the particles. The propulsion mechanism, power source, and motion effect of the particles based on the three kinds of propulsion micro-structures were investigated. To better understand the physical mechanism behind the experimental phenomena, physical model of micro-structures were established. The experimental and simulation results demonstrate that the oriented laser propulsion based on three kinds of fiber propulsion micro-structures was dominated by the shock wave ejection mechanism, which was caused by the high pressure of the shock wave. By analyzing the positions of characteristic peaks in the plasma spectra, it is proved that the driving force of particle motion derives from the shock wave formed by the expansion of air plasma. In the process of particle oriented propulsion, it is found that the motion effect of particles strongly depends on the propulsion micro-structure design, laser energy, particle size as well as gap distance d, and it is found that compared with the tapered fiber and flat fiber micro-structure oriented propulsion experiment, the motion effect of particles based on fiber-capillary micro-structure propulsion experiment is more obvious. In addition, based on the characteristic that the fiber oriented laser propulsion micro-structures can realize the directional propulsion of particles, and the micro-structure has shown potential application value in microinjection, laser fun billiard ball, and directional removal of contamination particles inside microsystems, providing theoretical support for later research.

Intermittency analysis of charged particles generated in Xe-Xe~collisions at $\sqrt{s_{\rm{NN}}}$ = 5.44 TeV using the AMPT model

The multiplicity fluctuations are sensitive to QCD phase transition and to the presence of critical point in QCD phase diagram. At critical point a system undergoing phase transition is characterized by large fluctuations in the observables which is an important tool to understand the dynamics of particle production in heavy-ion interactions and phase changes. Multiplicity fluctuations of produced particles is an important observable to characterize the evolving system. Using scaling exponent obtained from the normalized factorial moments of the number of charged hadrons in the two dimensional (\eta,\phiη,ϕ) phase space, one can learn about the dynamics of system created in these collisions. Events generated using Xe-Xe collisions at $ = 5.44 $ TeV with string-melting (SM) version of the AMPT model are analyzed and the scaling exponent (\nu)(ν) for various p_TpT intervals is determined. It is observed that the calculated value of \nuν is larger than the universal value 1.304, as is obtained from Ginzburg-Landau theory for second order phase transition. Here we will also present the results of the dependence of the scaling exponent on the transverse momentum bin width.

Comparative analysis of the effects of different purification methods on the yield and purity of cow milk extracellular vesicles

AbstractIsolation of extracellular vesicles (EV) has been developing rapidly in parallel with the interest in EVs. However, commonly utilized protocols may not suit more challenging sample matrixes and could potentially yield suboptimal results. Knowing and assessing the pitfalls of isolation procedure to be used, should be involved to some extent for EV analytics. EVs in cow milk are of great interest due to their abundancy and large‐scale availability as well as their cross‐species bioavailability and possible use as drug carriers. However, the characteristics of milk EVs overlap with those of other milk components. This makes it difficult to isolate and study EVs individually. There exists also a lack of consensus for isolation methods. In this study, we demonstrated the differences between various differential centrifugation‐based approaches for isolation of large quantities of EVs from cow milk. Samples were further purified with gradient centrifugation and size exclusion chromatography (SEC) and differences were analyzed. Quality measurements were conducted on multiple independent platforms. Particle analysis, electron microscopy and RNA analysis were used, to comprehensively characterize the isolated samples and to identify the limitations and possible sources of contamination in the EV isolation protocols. Vesicle concentration to protein ratio and RNA to protein ratios were observed to increase as samples were purified, suggesting co‐isolation with major milk proteins in direct differential centrifugation protocols. We demonstrated a novel size assessment of vesicles using a particle mobility analyzer that matched the sizing using electron microscopy in contrast to commonly utilized nanoparticle tracking analysis. Based on the standards of the International Society for Extracellular Vesicles and the quick checklist of EV‐Track.org for EV isolation, we emphasize the need for complete characterization and validation of the isolation protocol with all EV‐related work to ensure the accuracy of results and allow further analytics and experiments.

Study on spray characteristics of a compact pressure swirl nozzle integrating tangential inlet flow channel and swirl chamber

Pressure swirl nozzles are widely applied in various heat and mass transfer applications due to advantages of reliable performance, simple structure, and easy processing. However, the complex design of the nozzle structure makes it difficult to miniaturize the pressure swirl nozzle, which restricts its use in limited spaces. In this study, a compact pressure swirl nozzle is proposed by merging a swirl chamber with the tangential inlet flow channel, addressing the issue of liquid atomization in limited spaces. The key geometric parameters are determined based on the internal flow properties by swirl chamber simulation. A spray test bench utilizing a phase Doppler particle analyzer and a high-speed camera was built to study the effect of pressure drop, geometric size, and nozzle inlet shape on spray characteristics. The simulation results show that the nozzle diameter and inlet shape are the main factors affecting flow in the swirl chamber. The experimental results further demonstrate that increasing nozzle diameter increases flow rate and spray cone angle, causing the droplets to move to the spray edge. The spray characteristics are affected by the inlet shape of the nozzle hole: radial velocity and particle size show a wider range of change with a funnel-shaped inlet. Axial velocity and pressure drop are obviously affected by a cylindrical-shaped inlet. This study provided a new design approach for pressure swirl nozzles and achieved flow rate of 5–35 l/h and Sauter mean diameter below 40 μm with an overall weight of 12 g. This compact nozzle construction is a reference for the design of atomizing nozzles in limited spaces.

Prediction for Arrival Time and Parameters of Corotation Interaction Regions using Earth–Mars Correlated Events from Tianwen-1, MAVEN, and Wind Observations

Using the Stream Interaction Regions list from the Tianwen-1/Mars Orbiter Magnetometer (MOMAG) data between 2021 November and 2021 December and from Wind observations, we present an accurate prediction for the arrival time and in situ parameters of corotating interaction regions (CIRs) when the Earth and Mars have large longitudinal separations. Since CIRs were detected earlier at Earth than at Mars during the period examined, we employ Earth-based CIR detections for predicting CIR observations at Mars. The arrival time is calculated by the Parker spiral model under the assumption of steady corotation of the Sun and coronal holes, while the in situ parameters are derived from Wind data through radial dependent scaling laws. The CIR prediction results are compared to the actual observations obtained from the MOMAG and Mars Ion and Neutral Particle Analyzer instruments onboard Tianwen-1, as well as the Magnetometer and Solar Wind Ion Analyzer instruments onboard MAVEN. The predicted arrival time is close to the observed values with relative errors less than 10%, and the expected in situ data show a good consistency with the Martian measurements. The comparison results indicate that the prediction method has good performance and will be helpful for comparative analysis with Tianwen-1 observations at Mars in the future.

RESEARCH OF DISPERSION PROPERTIES OF OILCAKES

This article presents the results of research on the dispersion properties of oilseed cakes after oil extraction for further use in the bakery, confectionery, and pasta industries. Soybean, pumpkin, sunflower, peanut, and flax seed cakes were used in the work. Oilseed cakes are a high-protein product and can serve as an alternative gluten-free raw material for the production of flour products. The microstructural characteristics of the oilcake's surface were determined using an electron microscope-micro analyzer JXA-8230 from JEOL at the Scientific Center for Composite Materials LLP, Almaty. Sample images were obtained at an accelerating voltage of 20 kV, an electron beam current of much less than 1 nA, and aperture diaphragms No. 3 and 4. Laser analysis of particles of the applied materials up to nanoparticles was also performed. The smallest particle distribution is in sunflower cake (D10=3.177 um, D50=6.403 um, D90=10.007 um, Dav=6.529 um), the largest is in flax cake (D10=34.127 um, D50=61.243 um, D90=89.052 um, Dav=61.519 um). The research aimed to establish the microstructure and analysis of the particles of oilseed cakes and further influence the phase transformations and technological properties of bakery, confectionery, and pasta products.

Towards a reference material for microplastics’ number concentration—case study of PET in water using Raman microspectroscopy

Increasing demand for size-resolved identification and quantification of microplastic particles in drinking water and environmental samples requires the adequate validation of methods and techniques that can be used for this purpose. In turn, the feasibility of such validation depends on the existence of suitable certified reference materials (CRM). A new candidate reference material (RM), consisting of polyethylene terephthalate (PET) particles and a water matrix, has been developed. Here, we examine its suitability with respect to a homogeneous and stable microplastic particle number concentration across its individual units. A measurement series employing tailor-made software for automated counting and analysis of particles (TUM-ParticleTyper 2) coupled with Raman microspectroscopy showed evidence of the candidate RM homogeneity with a relative standard deviation of 12% of PET particle counts involving particle sizes >30 µm. Both the total particle count and the respective sums within distinct size classes were comparable in all selected candidate RM units. We demonstrate the feasibility of production of a reference material that is sufficiently homogeneous and stable with respect to the particle number concentration.Graphical

Lusca: FIJI (ImageJ) based tool for automated morphological analysis of cellular and subcellular structures

The human body consists of diverse subcellular, cellular and supracellular structures. Neurons possess varying-sized projections that interact with different cellular structures leading to the development of highly complex morphologies. Aiming to enhance image analysis of complex biological forms including neurons using available FIJI (ImageJ) plugins, Lusca, an advanced open-source tool, was developed. Lusca utilizes machine learning for image segmentation with intensity and size thresholds. It performs particle analysis to ascertain parameters such as area/volume, quantity, and intensity, in addition to skeletonization for determining length, branching, and width. Moreover, in conjunction with colocalization measurements, it provides an extensive set of 29 morphometric parameters for both 2D and 3D analysis. This is a significant enhancement compared to other scripts that offer only 5–15 parameters. Consequently, it ensures quicker and more precise quantification by effectively eliminating noise and discerning subtle details. With three times larger execution speed, fewer false positive and negative results, and the capacity to measure various parameters, Lusca surpasses other existing open-source solutions. Its implementation of machine learning-based segmentation facilitates versatile applications for different cell types and biological structures, including mitochondria, fibres, and vessels. Lusca’s automated and precise measurement capability makes it an ideal choice for diverse biological image analyses.

Numerical Analysis of Non-Sphericity of Particles of Powder Material and their Effect on Packing Structure for Concentrated Solar Power Applications

Concentrated solar power technology represents a novel approach to generating solar power, characterized by high solar radiation density and uninterrupted operation. To store thermal energy and extend system operating hours, concentrated solar power systems rely on thermal energy storage. Selecting the appropriate heat storage media is crucial for designing a cost-efficient and straightforward system capable of withstanding high processing conditions. Among many powder materials, bauxite powder stands out as alternatives to conventional molten salt for thermal storage media due to its widespread availability and suitability for operating conditions. Particle shape, particularly its sphericity, plays a vital role in efficiently packing particles which directly affects to heat transfer properties. To investigate this effect, three samples of particles with different shape were formed: spheres, ellipses, and cylinders using Discrete Element Method with equal volume and material properties, and only variation of their sphericity factors. The study focused on the analysis of the porosity of the packed bed of particles with different shapes and its influence on the packing structure properties. The analysis of local packing fraction revealed that elliptical and cylindrical particles samples exhibited reduced heap formation and a more uniform distribution along z direction during vertical packing. The coordination number and radial distribution function analyses for these non-spherical particles showed a greater number of contacts between particles and disordered distribution of particles due to mechanical interlocking of non-spherical particles. The results indicated that the deviation of sphericity has a positive impact on the denser packing of particles generated more contacts and higher local packing fraction.

Nanoparticles in terrestrial sediments and the behavior of the spectral optics of Sentinel-3B OLCI Satellite images in a river basin of UNESCO World Cultural and Natural Heritage.

The dangerous chemical elements associated with nanoparticles (NPs) and ultra-fine sediment particles in hydrological bays have the capacity to move contaminants to large oceanic regions. The general objective of this study is to quantify the major chemical elements present in NPs and ultra-fine particles in aquatic sediments sampled from Guanabara Bay and compare these data to values determined through spectral optics using the Sentinel-3B Satellite OLCI (Ocean Land Color Instrument) during the winter and summer seasons of 2018, 2019, 2020, 2021, and 2022. This is done to highlight the impacts anthropogenic environmental hazards have on the marine ecosystem and human beings. Ten aquatic sediment field collection points were selected by triangulated irregular network (TIN). Samples were subjected to analysis by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersion spectroscopy (EDS), and transmission electron microscopy (TEM), which enabled a detailed analysis using scanning transmission electron microscopy (STEM). Geospatial analyses using Sentinel-3B OLCI Satellite images considered Water Full Resolution (WFR) at 300m resolution, in neural network (NN), normalized at 0.83µg/mg. A maximum average spectral error of 6.62% was utilized for the identification of the levels of Absorption Coefficient of Detritus and Gelbstoff (ADG443_NN) at 443m-1, Chlorophyll-a (CHL_NN) (m-3), and Total Suspended Matter (TSM_NN) (g m-3) at 581 sample points. The results showed high levels of ADG443_NN, with average values as high as of 4444m-1 (summer 2021). When related to the analyses of nanoparticulate sediments and ultrafine particles collected in the field, they showed the presence of major chemical elements such as Ge, As, Cr, and others, highly toxic to human health and the aquatic environment. The application of satellite and terrestrial surveys proved to be efficient, in addition to the possibility of this study being applied to other hydrological systems on a global scale.

Ceramic Particle Reinforced Camshaft Lobes: A Performance Evaluation and Comparative Analysis

Ceramic reinforced metal matrix composite (CMMC) cams in engines could improve fuel efficiency and wear resistance compared to traditional steel cams but require absolute evaluation. However, ensuring safe CMMC cam operation demands extensive wear testing, mimicking real-world conditions over longer durations instead of limited lab evaluations. This study is an extension of the previously reported feasibility analysis of the ceramic particle reinforced Al matrix composite labs. The performance of the best selected (Al + 20, 30 vol. % SiC(2µm)) composites for a wear duration of 2.5, 5, 7.5, and 15 h is reported with various combinations of pressures and compared with the reference cam lobes. Results showed that the higher content of ceramic particles improved the wear resistance, however, the influence diminished at larger durations due to surface hardening of the composites. The wear performance of the composite (Al + 30 vol.% SiC) reaches 73% of the conventional cams but it also causes significant wear in the counterface due to initiation of three-body-wear by the dislodged ceramic particles.

Abstract 3633: Multi-parametric characterization of extracellular vesicles in the aqueous humor of uveal melanoma eyes undergoing brachytherapy

Abstract Introduction: Aqueous humor (AH), fluid in the anterior chamber of the eye, is a liquid biopsy source of tumor information in uveal melanoma (UM). Extracellular vesicles (EVs) have recently been characterized in the AH of retinoblastoma eyes, however, have not been investigated in UM. EVs are small membrane-enclosed particles secreted by virtually every cell type with a role in intercellular communications. We hypothesize that tumor-derived EVs are detectable in the AH of UM eyes and that understanding the type of vesicles present may help us better understand their function, particularly for cancer. Small extracellular vesicles (sEVs) have been shown to promote tumorigenesis, treatment resistance, and metastasis, leading to the discovery of clinically-relevant biomarkers for multiple cancer types. As the diversity and role of sEVs in the AH of UM patients has never previously been reported, this project is a first step towards investigating new biomarkers of clinical utility. Our aim is to use single particle analysis to characterize sEV subpopulations in the AH of UM patients by quantifying their size, concentration, and phenotypes based on cell surface markers, specifically tetraspanin co-expression patterns. Methods: sEVs were analyzed from paired pre- and post-brachytherapy AH samples collected from 19 UM patients. AH samples from 5 glaucoma patients served as the control cohort. Unprocessed AH underwent Nanoparticle Tracking Analysis for size quantification and Single Particle-Interferometric Reflectance Imaging Sensor analysis for fluorescent particle count and tetraspanin immunophenotyping; counts were subsequently converted to percentages for analysis. Statistics were performed using Mann-Whitney U, ANOVA, and Tukey’s tests. Results: AH derived from UM eyes (pre-brachytherapy) displayed a broader sEV size distribution than glaucoma eyes, with more diverse sEV subpopulations. Both tumor and nontumor AH samples demonstrated a dominant CD63+ sEV subpopulation. A significantly higher percentage of CD63/81+ sEVs (P= 0.0217) and CD9/63/81+ sEVs (P= 0.0146) were found in post-brachytherapy samples compared to pre-brachytherapy. Conclusions: sEV subpopulations in UM eyes demonstrate increased heterogeneity in comparison to nontumor eyes. Our results are consistent with prior studies reporting that the CD63+ sEV subtype is an AH-specific biomarker enriched across multiple ocular diseases. The increase in CD63/81+ sEVs and CD9/63/81+ sEVs after brachytherapy is presumably a result of radiation-induced release of these vesicles, suggesting a tumor-derived origin of these subpopulations. CD63/81+ sEV subpopulation was previously reported to also be a tumor-derived subpopulation in AH of retinoblastoma eyes. Further study of the cargo carried by these sEV subpopulations may uncover molecular mechanisms pivotal to UM and other ocular cancers. Citation Format: Shreya Sirivolu, Chen-Ching Peng, Paolo Neviani, Jesse L. Berry, Liya Xu. Multi-parametric characterization of extracellular vesicles in the aqueous humor of uveal melanoma eyes undergoing brachytherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3633.

Abstract 5735: Efficient and safe delivery of doxorubicin by DNA fragments: A full preclinical study

Abstract The clinical uses of anthracyclines (e.g., doxorubicin) are hampered especially by dose-dependent cardiac toxicity, resulting in a narrow therapeutic window. Doxorubicin formulations have marginally improved its therapeutic efficacy while suffering from difficult and costly manufacturing, poor characterization and quality control, limited scalability in production, and disappointingly low drug loading. This study employs DNA fragments extracted from the salmon sperm cells, which is known for high biocompatibility in various biomedical application, to self-assemble via intercalation by doxorubicin. DNA/DOX nanocomplexes are easy in manufacturing, high scalability, straightforward characterization and quantification, and efficiency in drug loading. Doxorubicin and DNA fragments were dissolved in water and mixed at the optimized 1:6 weight ratio, followed by stirring and incubation for 30 min. DNA/DOX nanocomplexes were characterized for doxorubicin loading and release, size, surface charge, and morphology by UV/fluorescence spectroscopy, stable isotope tracer ultrafiltration assay (SITUA), dynamic light scattering particle analysis, and transmission electron microscopy. The anticancer efficacy of the DNA/DOX nanocomplexes were tested in vitro and in vivo using syngeneic and PDX tumor models. Along with PD/PK studies, DNA/DOX nanocomplexes were also evaluated for their systemic and cardiac toxicity. Characterization and quantification studies revealed DNA/DOX nanocomplexes to be relatively monodisperse with a size of 40 nm in diameter, efficient for drug encapsulation (~100%) and drug loading (14.3%, w/w), and stable for storage while readily releasing doxorubicin in a cell. The self-assembled nanocomplexes were formed when doxorubicin inter- and intra-molecularly chelated DNA fragments. DNA/DOX nanocomplexes were more efficient in killing cancer cells in vitro than both doxorubicin and the liposomal doxorubicin Doxil. PD/PK studies demonstrated that DNA/DOX nanocomplexes circulated longer with less accumulation in the heart than doxorubicin, which altogether lower toxicity. A repeated administration of the DNA/DOX nanocomplexes to Sprague-Dawley rats exhibited a substantially lower cardiotoxicity score than that of doxorubicin. The improved anti-tumor efficacy of the DNA/DOX nanocomplexes were finally confirmed using a syngeneic lymphoma mouse model and PDX mouse models of triple-negative breast and ovarian cancers. Complexing doxorubicin with DNA fragments addresses the current technological challenges in achieving an efficient and safe therapy for a broad range of cancers. DNA/DOX nanocomplexes are amenable to rigorous chemistry, manufacturing, and controls (CMC) evaluation with proven anti-cancer efficacy and improved safety profiles. Clinical trials on DNA/DOX nanocomplexes for cancer chemotherapy are warranted to fully validate their clinical utilities. Citation Format: Minhyeong Park, Youngwoo Kim, Hyunchu Cho, Saad Mohammad, Yeon Su Choi, Hyunjoo Lee, Seonah Lee, Edward Cedrone, Barry Neun, Maria Dobrovolskaia, David Fruman, Juwan Kim, Young Jik Kwon. Efficient and safe delivery of doxorubicin by DNA fragments: A full preclinical study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5735.

Hematin- and Hemin-Induced Spherization and Hemolysis of Human Erythrocytes Are Independent of Extracellular Calcium Concentration.

Pathologies such as malaria, hemorrhagic stroke, sickle cell disease, and thalassemia are characterized by the release of hemoglobin degradation products from damaged RBCs. Hematin (liganded with OH-) and hemin (liganded with Cl-)-are the oxidized forms of heme with toxic properties due to their hydrophobicity and the presence of redox-active Fe3. In the present study, using the original LaSca-TM laser particle analyzer, flow cytometry, and confocal microscopy, we showed that both hematin and hemin induce dose-dependent RBC spherization and hemolysis with ghost formation. Hematin and hemin at nanomolar concentrations increased [Ca2+]i in RBC; however, spherization and hemolysis occurred in the presence and absence of calcium, indicating that both processes are independent of [Ca2+]i. Both compounds triggered acute phosphatidylserine exposure on the membrane surface, reversible after 60 min of incubation. A comparison of hematin and hemin effects on RBCs revealed that hematin is a more reactive toxic metabolite than hemin towards human RBCs. The toxic effects of heme derivatives were reduced and even reversed in the presence of albumin, indicating the presence in RBCs of the own recovery system against the toxic effects of heme derivatives.

Kinetics of Estonian Phosphate Rock Dissolution in Hydrochloric Acid

The kinetics of the dissolution of Estonian phosphate rock and the governing reaction mechanisms in hydrochloric acid in technological processes were investigated. The influences of particle size and acid concentrations of 0.5–1.5 M on the reaction rate and the pH variation during the process were studied at a dosage of 2.1 moles of HCl per mole of calcium for 60 min. The results indicated that the solubility of phosphorus reached 94%–100% for the fine samples and 82%–99% for the coarse samples. The time required to achieve an apparent steady-state pH reduced with the increasing acid concentrations and decreasing particle sizes. It was determined that the CaF2 precipitation in solutions starting at 1 M was faster at higher concentrations. The SEM surface analysis of the insoluble particles proved the existence of etch pit formation. The XPS and EDX analyses affirmed that the dissolution was incongruent. The surface composition of the unreacted particles gave a stoichiometry of CaF1.8, showing the formation of CaF2 on the surface. The dissolution kinetics were analyzed using the shrinking core model and showed a combination of chemical reaction, diffusion or interfacial transfer, and diffusion, sequentially for coarse particles or simultaneously for fine fractions.

Analysis of single particle and collective beam effects in high intensity beams in a periodic quadrupole channel

In high intensity proton accelerators, there are two main mechanisms that can cause beam degradation: incoherent and coherent effects due to nonlinear space charge forces. The incoherent effects represent the single particle dynamics while the coherent effects represent the collective response of the beam. Of particular interest is the region above a zero current phase advance (σ0) of 90° where the (coherent) second-order envelope instability and the (incoherent) fourth-order particle resonance are seen to lead to emittance growth. Large emittance growth is also seen below the envelope instability region as the full current beam phase advance (σ) decreases. In the present study, we have studied the nonlinear effects in a high intensity beam propagating through a focusing-defocusing (FD) quadrupole channel for σ0 greater than 90°, both analytically, by studying the solutions of Kapchinsky-Vladimirsky (KV) equation and the particle core model, and through detailed particle-in-cell (PIC) simulations using the code. The KV envelope equation gives the collective response of the beam while the particle core model gives the contribution of the single particle effects. With pic simulations, which resemble the behavior of the real beams more closely as compared to envelope calculations or the particle core model, it is possible to study the evolution of the beam in a self-consistent manner. Our studies show, that it is possible to identify the specific process responsible for beam degradation in high intensity beams. It is also possible to identify which process dominates under different conditions. We further show that the width of the emittance increase stop band calculated from PIC simulations is wider than that calculated by the envelope equations and that the width depends on the length of the channel being studied. Published by the American Physical Society 2024

The zinc finger motif in the mitochondrial large ribosomal subunit protein bL36m is essential for optimal yeast mitoribosome assembly and function

Ribosomes across species contain subsets of zinc finger proteins that play structural roles by binding to rRNA. While the majority of these zinc fingers belong to the C2-C2 type, the large subunit protein L36 in bacteria and mitochondria exhibits an atypical C2-CH motif. To comprehend the contribution of each coordinating residue in S. cerevisiae bL36m to mitoribosome assembly and function, we engineered and characterized strains carrying single and double mutations in the zinc coordinating residues. Our findings reveal that although all four residues markedly influence protein stability, C to A mutations in C66 and/or C69 have a more pronounced effect compared to those at C82 and H88. Importantly, protein stability directly correlates with the assembly and function of the mitoribosome and the growth rate of yeast in respiratory conditions. Mass spectrometry analysis of large subunit particles indicates that strains deleted for bL36m or expressing mutant variants have defective assembly of the L7/L12 stalk base, limiting their functional competence. Furthermore, we employed a synthetic bL36m protein collection, including both wild-type and mutant proteins, to elucidate their ability to bind zinc. Our data indicate that mutations in C82 and, particularly, H88 allow for some zinc binding albeit inefficient or unstable, explaining the residual accumulation and activity in mitochondria of bL36m variants carrying mutations in these residues. In conclusion, stable zinc binding by bL36m is essential for optimal mitoribosome assembly and function. MS data are available via ProteomeXchange with identifierPXD046465.

Particle analysis based on light extinction method illuminated by a divergent beam

A novel model based on the Monte Carlo principle was put forward to study the phenomenon of particle extinction spectrum under the condition of divergent incident beams and analyze the deviation during particle size inversion. Both the simulation results and experimental results show that the light extinction effect enhances obviously with the increase of divergence angle, accompanied by the distortion of extinction spectrum itself, which is closely related to particle size and optical wavelength. When the divergence angle is up to 20°, the observed relative error during the retrieval of particle size can reach 12.8%, by comparing those obtained by the Lamber-Beer law for particle to the nominal diameter of 0.8 μm. Accordingly, an improved inversion technique was studied, which yielded the particle size measurement error below2% for particles of 0.2 μm, 0.8 μm and 2.88 μm in nominal size.

ИССЛЕДОВАНИЕ ФИЗИКО-ХИМИЧЕСКИХ И ПРОТИВОИЗНОСНЫХ СВОЙСТВ МОТОРНЫХ МАСЕЛ ПО ЗАВЕРШЕНИИ ПРОЦЕССА ЭКСПЛУАТАЦИИ

There is given the study of viscous properties of engine oil, depending on the temperature before and after change on modern domestic gasoline and diesel cars, the determination of spectral characteristics and X-ray fluorescence analysis of wear particles after mileage. The degree of viscosity of semi-synthetic oils of two types is estimated. The oils were cooled and heated up to 150 °C. A digital viscometer was used, the dynamic viscosity of all oils decreased with increasing temperature, which is associated with oxidation in waste oil. To assess the effect of motor oil on engine operation, IR spectrometric analysis is performed and the thickness of the lubricating film is determined. The test results showed a qualitative and quantitative change in the characteristic frequencies of the new engine oil and the spent one after 10,000 km. X-ray fluorescence analysis makes it possible to analyze wear products and determine which mechanism in the engine is most susceptible to wear. Lines have characteristic absorption frequencies and indicate a change in physico-chemical properties of oil in the engine. An increase in contamination and in the viscosity of used oils is associated with the presence of impurities formed during the oxidation and polymerization of the base oil. It is necessary to increase the number of samples and sampling during different periods of operation so that you can verify the same effect throughout the entire engine operation. The results obtained indicate that these methods can be used to analyze and control the mode of operation of oils in the engine, allowing to determine the wear and further apply appropriate additives to the oil to improve performance properties.

Promotion of particle agglomeration by different vortex generator angles based on PIV-PDPA experiment

Turbulent agglomeration is a promising pretreatment technology aimed at enhancing fine particles removal efficiency. Recent studies suggested that V-structure vortex generators are effective in improving turbulence to promote particle collisions and size increase. However, the experimental studies on flow fields and particles induced by V-structure vortex generators with different angles are still insufficient. To this end, this study investigated the effect of the angle of V-structure vortex generators on particle agglomeration based on the experimental approach. More specifically, the flow field dynamics were obtained directly from a Particle Image Velocimetry, while the particle behavior and size variation were investigated by a Phase Doppler Particle Analyzer. The results of the Phase Doppler Particle Analyzer showed that the addition of the vortex generator and its angle increase led to an increase in average size as well as cross-particle size, while a decrease in number concentration of smaller particles, which confirmed the collisions between smaller particles. Through Particle Image Velocimetry experiments, it was found that a wider range of recirculation regions and counter-rotating eddies were generated. Furthermore, by analyzing particle distribution and tracking single particle trajectory through numerical simulation, two kinds of agglomeration mechanisms were proposed. One being the trajectory crossover of smaller particles triggered by recirculating vortex, and the other is the preferential concentration of larger particles. The results of this study can provide a theoretical basis for the design of V-structure vortex generators and particle agglomeration techniques.