Particles Of Different Sizes Research Articles

Investigation of lead particles loading on the surface of activated carbon on the performance of lead carbon batteries and its potential mechanisms

Loading lead particles on the surface of activated carbon (AC) is an effective strategy to further improve the performance of lead carbon batteries (LCBs). However, the influence of lead particle size on the properties of AC is ignored. Herein, AC loaded with lead phosphate particles of different sizes by ultrasonic adsorption is prepared. The results show that large size lead phosphate particles are conducive to the formation of lead carbon connection interphase with tens of microns, so as to avoid the electronic path failure of AC caused by sulfation. Moreover, with the increase of lead phosphate particle size, the cycle life under high rate partial state of charge (HRPSoC) and the capacity retention rate after 150 deep cycles under 60 % state of charge (SoC) increase by 49.12 % and 47.2 % respectively.

Multiplexed resistive pulse sensor based on geometry modulation for high-throughput microparticle counting

While resistive pulse sensor (RPS) has been used to characterize the nano/micro-targets (cells, biomolecules, etc.) in biomedical research, one long standing drawback is its low throughput. Here we report a novel geometry modulation based RPS to improve the throughput without increasing the complexity of measurement electronics. The sensor consists of multiple parallel sensing channels whose geometries are uniquely designed based on 7-bit spreading sequences. Because of the unique geometry, when a particle passes a sensing channel, the voltage signal from this channel is encoded by a specific waveform. Only a DC source was applied, and only one combined signal from all sensing channels was collected. For demodulation, the maximum correlation coefficient between the combined signal and each template waveform was used to identify the passage of a particle from a specific sensing channel, and the occurring time of the passage. An iterative cancellation scheme was developed to extract the identified waveforms, by a series of subtractions of the identified waveforms with amplitudes from high to low, until the correlation coefficients between the remaining signal with all template waveforms became less than 0.4 (weak correlation). Mixtures of different-sized polystyrene particles were used to test the device. Results showed that the device is capable of accurately sizing and counting various microparticles with errors of 5.8% and 5.2% while the throughput was improved 300%. With the simple structure and measurement setup, the geometry-modulated RPS has great potential for the detection and analysis of a variety of micro/nano bio-objects.

Simplified Interfacial Area Modeling in Polydisperse Two-Phase Flows under Explosion Situations

The aim of the present work is to account for polydisperse effects in a two-phase flow with a simple and fast method. Polydisperse two-phase flows arise in numerous applications. Fire sprinkler systems are relevant examples as they release clouds of polydisperse droplets. Another relevant example is the polydisperse two-phase flow created by the detonation of an explosive charge surrounded by a liquid layer. In such a situation, material interfaces are initially present and the created two-phase flow consists of a carrier gas phase and a liquid phase involving many droplets of various sizes. Spherical particles or droplets are usually assumed in two-phase flow computations. When dealing with explosion situations involving both dense and dilute flow regimes, multiple particle diameters can be addressed but at the price of introducing as many additional equations that describe mass, momentum and energy balance of the various particle classes. Consequently, the computation time needed to address numerical resolution increases tremendously. Under explosion situations involving many particle diameters, the method becomes intractable and is usually reduced to a single diameter, which is often insufficient. A simplified approach is developed in the present work to account for a substantial number of particles of different sizes with few extra computational cost. The approach is said to be simplified as a single velocity and a single temperature are considered for all the spherical particles, regardless of their diameters. This type of modeling seems apt for the target explosion situations. The focus is placed on the interfacial area, which is the main parameter involved in the coupling of the two phases. In the present work, Gamma-like continuous probability distributions are considered to address the various sizes of particles. The effects of the size distribution are only summarized in the specific interfacial area, yielding consequently few code modifications while taking into account the polydisperse aspect of the two-phase flow.

Магнитные свойства стекол, синтезированных на основе горных пород различного генезиса

The structural-phase, chemical composition and magnetic properties of artificial glasses obtained by high-temperature melting of rock mixtures of different genesis: volcanogenic-sedimentary rocks, quartzitic shales, psamite-silt-pelitic complexes were studied. Different in duration cooling and glass transition conditions were used for glass synthesis. The magnetic state of the iron-containing phase and the analysis of the presence and contribution of iron oxides to the magnetic properties were assumed to be the characteristic criterion determining the parameters of the glass formation process. It was shown that the total iron content in artificial glasses depends exclusively on the composition of the initial charge. In this case, the iron-containing component is mainly determined by sedimentary rocks. The formation of magnetic minerals is determined both by the composition of the charge and by the rate of cooling of the melt. During “fast” cooling, the formed magnetic particles are mostly (up to 90% or more of the total content of the magnetic phase in the sample) in a superparamagnetic state. During “slow” cooling, a mixture of particles of different sizes and, accordingly, in different magnetic states is formed: from superparamagnetic to low-domagnetic. The ferrimagnetic phase crystallizing in artificial glasses is represented by chemically heterogeneous aggregates of iron oxides, mainly non-stoichiometric magnetite.

Process intensification of hydrogen production by steam reforming of methane over structured channel packing catalysts

The industrial methane steam reforming reaction usually employs particulate catalyst that are easy to prepare and cost-effective, but suffer from problems such as high reactor pressure drop and low overall catalyst utilization. In this study, the Ni-Al2CaO4 powder prepared by the equal volume impregnation method was subjected to particle size control using a pressing method, and was made into catalyst particles of different sizes. Some of the catalysts were filled into honeycomb structures with cordierite and metal substrates, respectively, to prepare regular channel packing catalysts. The differences in methane steam reforming conversion rate, H2/CO selectivity, and overall pressure drop among the three catalysts were compared, and the influence of particle size and regular channel on reaction performance was systematically explored. The results showed that under the same conditions, as the catalyst particle size increased, the methane conversion rate and pressure drop increased. The regular channel packing catalysts with the two substrates showed similar pressure drop levels, but the metal substrate exhibited a higher methane conversion rate due to its excellent thermal conductivity. Compared with single-particle catalysts of the same size, the pressure drop of the metal substrate regular channel packing catalysts was reduced by more than 25%. Under the conditions of a gas hourly space velocity of 2000 h-1, a reaction temperature of 700 °C, and a water-to-carbon ratio of 3, the 40-60 mesh metal substrate regular packing catalysts showed a 7% increase in methane conversion rate, reaching 95.2%.

Reverse flow enhanced inertia pinched flow fractionation.

Particle separation plays a critical role in many biochemical analyses. In this article, we report a method of reverse flow enhanced inertia pinched flow fractionation (RF-iPFF) for particle separation. RF-iPFF separates particles by size based on the flow-induced inertial lift, and in the abruptly broadened segment, reverse flow is utilized to further enhance the separation distance between particles of different sizes. The separation performance can be significantly improved by reverse flow. Generally, compared with the case without reverse flow, this RF-iPFF technique can increase the particle throughput by about 10 times. To demonstrate the advantages of RF-iPFF, RF-iPFF was compared with traditional iPFF through a control experiment. RF-iPFF consistently outperformed iPFF across various conditions we studied. In addition, we use tumor cells spiked into the human whole blood to evaluate the separation performance of RF-iPFF.

Identifying Active Progeny Virus Particles in Formalin-Fixed, Paraffin-Embedded Sections Using Correlative Light and Scanning Electron Microscopy

Immunohistochemical analysis of formalin-fixed paraffin-embedded (FFPE) tissue blocks is routinely used to identify virus-infected cells. However, detecting virus particles in FFPE sections using light microscopy is difficult because of the light diffraction resolution limitations of an optical microscope. In this study, light microscopy and field emission scanning electron microscopy were performed to observe 3-dimensional virus particles in FFPE sections in a nondestructive manner using NanoSuit or osmium conductive treatment methods. The virus particles in FFPE sections were immunostained with specific antibodies against the surface antigens of the viral particles and stained with 3,3′-diaminobenzidine. A metal solution (0.2% gold chloride or 2% osmium tetroxide) was applied to enhance the 3,3′-diaminobenzidine–stained area. This procedure is nondestructive for FFPE sections and is a simpler method than transmission electron microscopy. To validate the applicability of this technique, we performed 3-dimensional imaging of the virus particles of different sizes, such as human papillomavirus, cytomegalovirus, and varicella-zoster virus. Furthermore, ultrathin sections from the FFPE sections that were observed to harbor viral particles using field emission scanning electron microscopy were prepared and assessed using transmission electron microscopy. In the correlative areas, transmission electron microscopy confirmed the presence of large numbers of virus particles. These results indicated that the combination of marking viral particles with 3,3′-diaminobenzidine/metal staining and conductive treatment can identify active progeny virus particles in FFPE sections using scanning electron microscopy. This easy correlative imaging of field emission scanning electron microscopy of the identical area of FFPE in light microscopy may help elucidate new pathological mechanisms of virus-related diseases.

Aqueous growth of titania subnanoparticles: an understanding of the ultrasmall visible-light-absorbing unit of (TiO2)8(H2O)16.

An atomistic understanding of the initial hydrothermal growth of titania remains crucial for the development of nanosized materials, where the presence of water strongly affects the particle growth in comparison to the vapor-phase growth. Herein, we explore the structural evolution of aqueous titania from its salt precursors and determine the nanoparticle configurations in the practical environment by invoking ab initio molecular dynamic simulations and a machine-learning accelerated structural search. Thermodynamically, Ti(OH)4·2H2O serving as the hydrated monomer undergoes planar-to-tubular-to-spherical multistage growth in the Ti(OH)4/H2O hydrothermal system, in which large-sized (TiO2)n(H2O)m particles (n = 1-20) are generated via the olation/oxolation reaction. Importantly, in a mixture of particles of different sizes, we identify that (TiO2)8(H2O)16 is one of the most abundant species in solution with peculiar metastability and exhibits extraordinary visible-light absorption ability, which may be the smallest aqueous titania subnanoparticle in the form of suspension and worth exploring for photocatalytic applications.

Immunogold for Protein Location in Chromaffin Cells.

The localization and density of any plasma membrane or intracellular protein in chromaffin cells are prerequisites for those studies designed to elucidate their contribution to cellular function within the adrenal gland and can be achieved only by immunoelectron microscopy. The most popular immunoelectron microscopic techniques involved gold particles conjugated to secondary antibodies, leading to electron-dense markers and the so-called immunogold EM method. Two main immunogold electron microscopic techniques exist: the pre-embedding immunogold, whereby the immunolabeling steps take place before samples are embedded, and the post-embedding immunogold, where the immunolabeling steps take place on embedded and sectioned samples. Pre-embedding immunogold is a very sensitive technique useful for simultaneous observation of labeled tissue at the light and electron microscopic levels. Post-embedding immunogold enables the simultaneous localization of different molecules in the cell using secondary antibodies conjugated with gold particles of different size. In this chapter, we introduce pre-embedding and post-embedding immunogold procedures used for the identification of quantitative changes in a wide range of signaling molecules in different tissues and also discuss the limitations inherent to these approaches.

Granular column collapse: The role of particle size polydispersity on the velocity and runout

Geophysical mass flows involve particles of different sizes, a property termed polydispersity. The granular column collapse is a simplified experiment for studying transitional granular flows. Our research focuses on the role that polydispersity has on the velocity and runout distance of dry and immersed granular columns, undergoing a numerical and experimental study. Our results highlight that polydispersity does not have a strong effect on the collapse of dry columns. On the contrary, the collapse sequence of immerse granular columns strongly depend on the polydispersity level.

Assessing the impact of specific weight of different-sized particles on operational performance of coal preparation plant

In case of firing pulverized coal in power steam boiler certain fuel preparation process has to be taken in order to ensure stable and optimal combustion in boiler furnace. Before entering furnace low caloric coal is introduced from coal bunker to the coal preparation system where milling/pulverization and drying processes of raw large coal particles are conducted. For the purpose of defining fineness of grinding of pulverized coal mill gaseous mixture at mill outlet is introduced to the separator where large coal particles, separated from outgoing mill gaseous mixture, are recirculated to mill for regrinding. In this paper character of two-phase flow in inertial separator at milling plant in TPP Nikola Tesla Unit B under various operating conditions has been analyzed. The CFD approach has been used for calculating two-phase flow in separators flow domain. Measurement data taken on site along with results of performed heat balance calculations of milling plant have been used for validating calculation model as well as for setting appropriate boundary conditions in CFD model. The CFD calculations has been performed for different positions of all regulating flaps, recirculation rates of gaseous phase and values of specific weight of solid phase in two-phase mixture. For evaluating separators operating performance at different operating regimes changes of milling capacity and fineness of grinding of pulverized coal at separators outlet have been observed. Additionally, deviation rate of trajectories of different-sized particles to the streamlines of gaseous phase has been examined.

High-density lipoprotein subclasses and cardiovascular disease and mortality in type 2 diabetes: analysis from the Hong Kong Diabetes Biobank

ObjectiveHigh-density lipoproteins (HDL) comprise particles of different size, density and composition and their vasoprotective functions may differ. Diabetes modifies the composition and function of HDL. We assessed associations of HDL size-based subclasses with incident cardiovascular disease (CVD) and mortality and their prognostic utility.Research design and methodsHDL subclasses by nuclear magnetic resonance spectroscopy were determined in sera from 1991 fasted adults with type 2 diabetes (T2D) consecutively recruited from March 2014 to February 2015 in Hong Kong. HDL was divided into small, medium, large and very large subclasses. Associations (per SD increment) with outcomes were evaluated using multivariate Cox proportional hazards models. C-statistic, integrated discrimination index (IDI), and categorial and continuous net reclassification improvement (NRI) were used to assess predictive value.ResultsOver median (IQR) 5.2 (5.0–5.4) years, 125 participants developed incident CVD and 90 participants died. Small HDL particles (HDL-P) were inversely associated with incident CVD [hazard ratio (HR) 0.65 (95% CI 0.52, 0.81)] and all-cause mortality [0.47 (0.38, 0.59)] (false discovery rate < 0.05). Very large HDL-P were positively associated with all-cause mortality [1.75 (1.19, 2.58)]. Small HDL-P improved prediction of mortality [C-statistic 0.034 (0.013, 0.055), IDI 0.052 (0.014, 0.103), categorical NRI 0.156 (0.006, 0.252), and continuous NRI 0.571 (0.246, 0.851)] and CVD [IDI 0.017 (0.003, 0.038) and continuous NRI 0.282 (0.088, 0.486)] over the RECODe model.ConclusionSmall HDL-P were inversely associated with incident CVD and all-cause mortality and improved risk stratification for adverse outcomes in people with T2D. HDL-P may be used as markers for residual risk in people with T2D.

Axial segregation behaviour of a reacting biomass particle in fluidized bed reactors: experimental results and model validation

Axial segregation behaviour of a single biomass particle in a lab-scale bubbling fluidized bed has been investigated from both experimental and modelling perspectives. Experiments were conducted using beech wood particles of different sizes, ranging from 8 to 12 mm under either oxidizing or inert conditions. The fluidized bed reactor was operated at temperatures and fluidization velocity ratios, U/Umf, in the range of 500–650 °C and 1–2, respectively. A one-dimensional model has been developed to predict the axial location of the particle over time, taking into account both dynamic and thermal conversion mechanisms. X-ray imaging techniques allowed to identify endogenous bubbles released during devolatilization and carry out direct measurements of their size. This information was used to propose an expression for the lift force acting on the fuel particle. The model showed very accurate predictions and the segregation behaviour of the fuel particle appeared to be independent of the nature of the fluidizing medium.

Improved corrosion resistance of nickel-aluminum bronze by electron beam powder bed fusion

The corrosion resistance of nickel-aluminum bronze (NAB) by electron beam powder bed fusion (EB-PBF) from different-size feeding particles is investigated in neutral 3.5 wt% NaCl solutions. Uniformly-distributed precipitates are observed in the samples at the microscale. The βˊ phase that suffered from corrosion preferentially in conventional as-casting NAB is not observed in the EB-PBF NAB. Typically, the corrosion resistance of EB-PBF NAB built from middle-size particles is improved by 1.35 times that of as-casting NAB. This results from a collective effect of high relative density and uniformly-distributed precipitates, which mitigates selective phase corrosion and promotes the formation of corrosion products with uniform thickness.

Distribution characteristics of particles in room with capillary radiant floor heating system

Based on discrete phase model (DPM) and Euler-Lagrange method, a heat transfer model is established for capillary radiant floor coupled with indoor particle diffusion in this paper. The distribution is analyzed for the temperature in surface of floor and particles in indoor room. The concentration distribution characteristics of indoor particle in different sizes are further analyzed under the condition of different floor finishing layers. The results show that many particles are deposited around human body and the wall, and the diffusion height of particles in different sizes increases with the increase of floor surface temperature. Meanwhile, the 2.5 μm particles are more greatly affected by temperature difference and diffuses broader compared with 10 μm particles. The concentration of 10 μm particles decreases more obviously in height direction than that of 2.5 μm particles. In addition, the concentration of particles is the highest at the height of 0.6 m children breathing height. The results are significant for improving the design of capillary radiant floor heating system.

Simultaneous Sizing and Refractive Index Analysis of Heterogeneous Nanoparticle Suspensions.

Rapid and reliable characterization of heterogeneous nanoparticle suspensions is a key technology across the nanosciences. Although approaches exist for homogeneous samples, they are often unsuitable for polydisperse suspensions, as particles of different sizes and compositions can lead to indistinguishable signals at the detector. Here, we introduce holographic nanoparticle tracking analysis, holoNTA, as a straightforward methodology that decouples size and material refractive index contributions. HoloNTA is applicable to any heterogeneous nanoparticle sample and has the sensitivity to measure the intrinsic heterogeneity of the sample. Specifically, we combined high dynamic range k-space imaging with holographic 3D single-particle tracking. This strategy enables long-term tracking by extending the imaging volume and delivers precise and accurate estimates of both scattering amplitude and diffusion coefficient of individual nanoparticles, from which particle refractive index and hydrodynamic size are determined. We specifically demonstrate, by simulations and experiments, that irrespective of localization uncertainty and size, the sizing sensitivity is improved as our extended detection volume yields considerably longer particle trajectories than previously reported by comparable technologies. As validation, we measured both homogeneous and heterogeneous suspensions of nanoparticles in the 40-250 nm size range and further monitored protein corona formation, where we identified subtle differences between the nanoparticle-protein complexes derived from avidin, bovine serum albumin, and streptavidin. We foresee that our approach will find many applications of both fundamental and applied nature where routine quantification and sizing of nanoparticles are required.

WC-reinforced iron matrix composites fabricated by wire arc additive manufacturing combined with gravity-driven powder feeding: particle transportation and size effects

Purpose A new wire arc additive manufacturing (WAAM) process combined with gravity-driven powder feeding was developed to fabricate components of tungsten carbide (WC)-reinforced iron matrix composites. The purpose of this study was to investigate the particle transportation mechanism during deposition and determine the effects of WC particle size on the microstructure and properties of the so-fabricated component. Design/methodology/approach Thin-walled samples were deposited by the new WAAM using two WC particles of different sizes. A series of in-depth investigations were conducted to reveal the differences in the macro morphology, microstructure, tensile performance and wear properties. Findings The results showed that inward convection and gravity were the main factors affecting WC transportation in the molten pool. Large WC particles have higher ability than small particles to penetrate into the molten pool and survive severe dissolution. Small WC particles were more likely to be completely dissolved around the top surface, forming a thicker region of reticulate (Fe, W)6C. Large WC particles can slow down the inward convection more, thereby leading to an increase in width and a decrease in the layer height of the weld bead. The mechanical properties and wear resistance significantly increased owing to reinforcement. Comparatively, samples with large WC particles showed inferior tensile properties owing to their higher susceptibility to cracks. Originality/value Fabricating metal matrix composites through the WAAM process is a novel concept that still requires further investigation. Apart from the self-designed gravity-driven powder feeding, the unique aspects of this study also include the revelation of the particle transportation mechanism of WC particles during deposition.

Size effect of gold nanoparticles in bimetallic ZIF catalysts for enhanced photo-redox reactions

It is well known that gold nanoparticles have been widely used in various photo-redox reactions because of the unique surface plasmon resonance effect and the excellent internal electron transfer ability. However, the essential factors of how the metal nanoparticles enhancing the activity of photocatalysts have not been fully revealed. In this paper, gold colloidal particles of different sizes were modified on the surface of the dodecahedral skeleton of ZIF-Co/Zn. The photocatalytic activity of Au@ZIF-Co/Zn was investigated under simulated visible light for treating Rhodamine B/Cr(VI) mixture solutions (RhB/Cr(VI) 20 mg/L) and 4-nitrophenol solution (4-NP 20 mg/L). The results indicate that the size of gold nanoparticles could affect the surface plasmon resonance effect observably, internal electron transfer capacity and carrier density change. Photoelectric chemistry experiments and radical quenching experiments were performed to reveal the charge-transfer photocatalytic mechanism and size influence of gold nanoparticles in composite photocatalysts. This work may provide a novel strategy for the construction of metal–organic frameworks for the purification of wastewater mixed with heavy metal ions, organic pollutants and pharmaceutical intermediates.

Experimental assessment of the thermo-mechanical bond behavior of NSM CFRP with cement-based adhesives

Cement-based materials, which are incombustible and show low thermal diffusivity, show great potential as a valid alternative to polymeric matrices for bonding near surface mounted (NSM) carbon fiber reinforced polymer (CFRP) systems for the strengthening of reinforced concrete (RC) structures. The performance of these materials in different loading conditions, including high temperature exposure, still needs to be better explored. This paper presents a study on the characterization of the bond behavior using cement-based adhesives and CFRP strips with innovative surface treatment. The CFRP strips used in this study were manufactured specifically with sand-treated surfaces to improve the bonding performance between CFRP and cement-based adhesive by taking advantage of the better grip of increased roughness surfaces. The results of the pull-out tests in ambient conditions, as well as exposed to elevated temperatures, are presented and discussed. The effect of using sand particles of different sizes, adhered with two different resins on the CFRP strips surface embedded in different cement-based matrices, was compared. The obtained results showed that by applying a sand treatment on the surface of CFRP strips, the maximum pull-out force was up to 12 times higher than when using smooth surfaced strips. Pull-out tests showed that, by using the NSM sand treated CFRP strips and CFRP bars with cement-based adhesive, an average bond strength up to about 9 MPa and 11 MPa, respectively, could be achieved. Thermo-mechanical pull-out tests showed the proposed strengthening system is able to withstand up to 30 min of heat exposure before bond failure.

Random matrix theory of polarized light scattering in disordered media

In this work we present a method for generating random matrices describing electromagnetic scattering from disordered media containing dielectric particles with prescribed single particle scattering characteristics. Resulting scattering matrices automatically satisfy the physical constraints of unitarity, reciprocity and time reversal, whilst also incorporating the polarization properties of electromagnetic waves and scattering anisotropy. Our technique therefore enables statistical study of a variety of polarization phenomena, including depolarization rates and polarization-dependent scattering by chiral particles. In this vein, we perform numerical simulations for media containing isotropic and chiral spherical particles of different sizes for thicknesses ranging from the single to multiple scattering regime and discuss our results, drawing comparisons to established theory.