Different Types Of Particles Research Articles

POMDP-Based Real-Time Path Planning for Manipulation of Multiple Microparticles via Optoelectronic Tweezers.

With high throughput and high flexibility, optoelectronic tweezers (OETs) hold huge potential for massively parallel micromanipulation. However, the trajectory of the virtual electrode has been planned in advance in most synchronous manipulations for multiple targets based on an optically induced dielectrophoresis (ODEP) mechanism, which is insufficient to ensure the stability and efficiency in an environment with potential collision risk. In this paper, a synchronously discretized manipulation method based on a centralized and decoupled path planner is proposed for transporting microparticles of different types with an OET platform. An approach based on the Kuhn-Munkres algorithm is utilized to achieve the goal assignment between target microparticles and goal positions. With the assistance of a visual feedback module, a path planning approach based on the POMDP algorithm dynamically determines the motion strategies of the particle movement to avoid potential collisions. The geometrical parameters of the virtual electrodes are optimized for different types of particles with the goal of maximum transport speed. The experiments of micropatterning with different morphologies and transporting multiple microparticles (e.g., polystyrene microspheres and 3T3 cells) to goal positions are performed. These results demonstrate that the proposed manipulation method based on optoelectronic tweezers is effective for multicell transport and promises to be used in biomedical manipulation tasks with high flexibility and efficiency.

Analysis of technological parameters of cast composite materials with a matrix of light alloys manufacture

The successful functioning and further development of most modern industries, such as aerospace, transport, military, biomedicine, is not possible without the use of lightweight, durable and inexpensive materials to manufacture. Light alloys are widely used in industry and everyday life due to the high complex of physical and mechanical properties, wear and corrosion resistance as well as low cost. In this regard, the use of light alloys as a basis for composite materials is justified and expedient. The properties of the finished composite material exceed the properties of its constituent components. The potential of these materials has not been fully used to this day despite the growing interest in metal matrix composites and extensive investigations aimed at the development of production technology and the introduction of advanced systems based on light matrices. The article presents a brief review of the literature on the analysis of the main components of the technology of cast composite materials (CCM) based on light alloys of aluminum and magnesium reinforced by particles of different types. Particular attention is paid to the choice of the matrix alloy, the type, size and amount of reinforcing particles introduced into it, as well as the thermal-time and kinetic parameters of the process. The matrix alloy must be uniform, strong, light and inexpensive. The particles must have a high hardness and be optimally distributed in the matrix, to be securely fixed in it. An important element of the technology of manufacturing CCM by liquid-phase method is also a method of introducing solid particles of liquid metal. Several ways of introducing reinforcing particles into the melt were analysed too. Only the optimal combination of all these elements can provide composite materials with a high level of physical, mechanical and operational properties. In addition, the article suggests directions for further research in this area

Subtomogram analysis: The sum of a tomogram’s particles reveals molecular structure in situ

Cryo-electron tomography is uniquely suited to provide insights into the molecular architecture of cells and tissue in the native state. While frozen hydrated specimens tolerate sufficient electron doses to distinguish different types of particles in a tomogram, the accumulating beam damage does not allow resolving their detailed molecular structure individually. Statistical methods for subtomogram averaging and classification that coherently enhance the signal of particles corresponding to copies of the same type of macromolecular allow obtaining much higher resolution insights into macromolecules. Here, I review the developments in subtomogram analysis at Wolfgang Baumeister’s laboratory that make the dream of structural biology in the native cell become reality.

АЛГОРИТМ ОЦЕНКИ ЭФФЕКТИВНОСТИ НЕЙРОННЫХ СЕТЕЙ ДЛЯ n/γ-РАЗДЕЛЕНИЯ В ОРГАНИЧЕСКИХ СЦИНТИЛЛЯТОРАХ

Machine learning is one of the leading directions in digital signal processing. For example, in neutron spectrometry, artificial neural networks are actively used to suppress gamma background when analyzing signals from scintillation detectors. This article describes a method for determining the quality of n/γ-separation by an artificial neural network. The efficiency of the method is demonstrated by analyzing the signals obtained by measuring the prompt neutron spectrum of 252Cf spontaneous fission using a scintillation detector based on a stilbene crystal. The essence of the method is to determine the proportion of falsely identified events for each of the analyzed signal classes using a known reference method. An exemplary gamma-ray source was used to determine the false count of recoil protons. This approach made it possible to estimate the fraction of events from electrons identified as recoil protons and the fraction of recoil protons perceived as electrons, depending on the light yield of the scintillation signal. This, in turn, made it possible to reconstruct the true energy spectra for different types of particles, including for the region of low signal amplitudes, where the separation quality is usually poor. The reconstructing error was less than 8 % for the light yield region of less than 120 keVee.

A generic metasurface for the optical pulling of dielectric or plasmonic or chiral Mie objects

In the year 1902, scientists observed a phenomenon occurring at metal interface, known as Wood’s anomaly, which led to the discovery of SPP (Surface Plasmon Polariton). Since then, SPP has received a great deal of attention due to its ability to direct light in the sub-wavelength scale. Their ability to pull objects of various materials, however, has not been thoroughly studied yet. Notably, creating pulling force for different types of particles in a single setup is quite challenging and rare in the literature. In this article, we propose a methodology through which exerting pulling force on spherical dielectric or plasmonic or chiral objects has been made possible within a common diameter range in an on-chip configuration by shining the light from the bottom of a metasurface. In our setup, two SPP waves have been excited by using periodic gratings made of metasurfaces placed on a metal–dielectric interface, which has created such optical pulling forces based on non-paraxial behavior of SPP. Pulling in dielectric object has been enabled due to the induced multipole radiation. The reversal of internal electric field and current density, due to interference field of SPP, has generated the pulling force for the plasmonic object. In contrast, the pulling force on chiral objects has been explained based on the direction of energy flow within the object. These changes occur when the SPP becomes non-paraxial enough for the three objects enabling on-chip object transportation and opening new boundaries for radius-based sorting, which can aid in the analysis of nanoparticle and biomolecules.

Uncoupled seasonal variability of transparent exopolymer and Coomassie stainable particles in coastal Mediterranean waters

Transparent exopolymer particles (TEP) and Coomassie stainable particles (CSP) are gel-like particles, ubiquitous in the ocean, that affect important biogeochemical processes including organic carbon cycling by planktonic food webs. Despite much research on both groups of particles (especially TEP) over many years, whether they exist as distinctly stainable fractions of the same particles or as independent particles, each with different driving factors, remains unclear. To address this question, we examined the temporal dynamics of TEP and CSP over 2 complete seasonal cycles at 2 coastal sites in the Northwestern Mediterranean Sea, the Blanes Bay Microbial Observatory (BBMO) and the L’Estartit Oceanographic Station (EOS), as well as their spatial distribution along a coast-to-offshore transect. Biological, chemical, and physical variables were measured in parallel. Surface concentrations (mean ± standard deviation [SD]) of TEP were 36.7 ± 21.5 µg Xanthan Gum (XG) eq L–1 at BBMO and 36.6 ± 28.3 µg XG eq L–1 at EOS; for CSP, they were 11.9 ± 6.1 µg BSA eq L–1 at BBMO and 13.0 ± 5.9 µg BSA eq L–1 at EOS. Seasonal variability was more evident at EOS, where surface TEP and CSP concentrations peaked in summer and spring, respectively, and less predictable at the shore-most station, BBMO. Vertical distributions between surface and 80 m, monitored at EOS, showed highest TEP concentrations within the surface mixed layer during the stratification period, whereas CSP concentrations were highest before the onset of summer stratification. Phytoplankton were the main drivers of TEP and CSP distributions, although nutrient limitation and saturating irradiance also appeared to play important roles. The dynamics and distribution of TEP and CSP were uncoupled both in the coastal sites and along the transect, suggesting that they are different types of particles produced and consumed differently in response to environmental variability.

Plastic and natural inorganic microparticles do not differ in their effects on adult mussels (Mytilidae) from different geographic regions

Microplastics are ubiquitous in the marine environment and studies on their effects on benthic filter feeders at least partly revealed a negative influence. However, it is still unclear whether the effects of microplastics differ from those of natural suspended microparticles, which constitute a common stressor in many coastal environments. We present a series of experiments that compared the effects of six-week exposures of marine mussels to two types of natural particles (red clay and diatom shells) to two types of plastic particles (Polymethyl Methacrylate and Polyvinyl Chloride). Mussels of the family Mytilidae from temperate regions (Japan, Chile, Tasmania) through subtropical (Israel) to tropical environments (Cabo Verde) were exposed to concentrations of 1.5 mg/L, 15 mg/L and 150 mg/L of the respective microparticles. At the end of this period, we found significant effects of suspended particles on respiration rate, byssus production and condition index of the animals. There was no significant effect on clearance rate and survival. Surprisingly, we observed only small differences between the effects of the different types of particles, which suggests that the mussels were generally equally robust towards exposure to variable concentrations of suspended solids regardless of whether they were natural or plastic. We conclude, that microplastics and suspended solids elicit similar effects on the tested response variables, and that both types of microparticles mainly cause acute responses rather than more persistent carry-over effects.

Dehydrogenation of ammonia borane recrystallized by different techniques

The literature shows that practically no attention has been paid to the size and shape of the particles of bulk ammonia borane (NH 3 BH 3 ). The published results about the influence of the dispersity of this hydride on its dehydrogenation are not numerous and contradictory. This work presents new results on the low-temperature solid-state dehydrogenation of bulk NH 3 BH 3 . The samples under study were recrystallized using different procedures and had, therefore, different particle characteristics. The reactivity of these samples of NH 3 BH 3 was compared on the basis of thermal analysis data obtained under non-isothermal conditions, including the Kissinger kinetics, and H 2 evolution under isothermal conditions (84–96°С) using Avrami-Erofeev kinetics. The finely dispersed sample with a particle size of <40 μm was found to be the most active one. A correlation between the NH 3 BH 3 melting temperature and the temperature of its dehydrogenation has been established. A filamentous NH 3 BH 3 with a length-to-thickness ratio of the filaments of >100 was synthesized and described for the first time. It was suggested that its relatively high reactivity was determined by its ordered structure. These results show the importance of further investigations of bulk ammonia borane with different types of particles. • Effect of dispersity of bulk NH 3 BH 3 (AB) on its dehydrogenation is still contradictory. • AB of different characteristics were prepared by different recrystallization methods. • Мelting temperature of AB correlates with the temperature of its dehydrogenation. • Finely dispersed AB with a particle size of <40 μm is the most active one. • Relatively high activity of non-dispersed but ordered filamentous AB is discussed.

Effect of particle characteristics on particle collision behaviors and heat transfer performance in a down-flow circulating fluidized bed evaporator

The effects of particle characteristics on particle collision behaviors and heat transfer are investigated based on standard deviation and kurtosis analysis in a down-flow circulating fluidized bed evaporator. Results show particle addition can enhance heat transfer for all types of particles. The maximum enhancing factor reaches 33.0% within the experimental range by adding polytetrafluoroethylene particles at ε=1.5%, V=5.16 m3/h and q = 8 kW/m2. For different types of particles, with increased amount of added particles, enhancing factor initially increases and then decreases; standard deviation increases but kurtosis decreases. With increased circulation flow rate, standard deviation and enhancing factor tend to increase but kurtosis decrease. With increased heat flux, standard deviation tends to increase but kurtosis and enhancing factor decrease. Density, sedimentation velocity and surface wetting performance obviously influence particle collision and heat transfer performance. High standard deviation and low kurtosis are beneficial to heat transfer.

Facile self-assembly of colloidal diamond from tetrahedral patchy particles via ring selection

Diamond-structured crystals, particularly those with cubic symmetry, have long been attractive targets for the programmed self-assembly of colloidal particles, due to their applications as photonic crystals that can control the flow of visible light. While spherical particles decorated with four patches in a tetrahedral arrangement-tetrahedral patchy particles-should be an ideal building block for this endeavor, their self-assembly into colloidal diamond has proved elusive. The kinetics of self-assembly pose a major challenge, with competition from an amorphous glassy phase, as well as clathrate crystals, leaving a narrow widow of patch widths where tetrahedral patchy particles can self-assemble into diamond crystals. Here we demonstrate that a two-component system of tetrahedral patchy particles, where bonding is allowed only between particles of different types to select even-member rings, undergoes crystallization into diamond crystals over a significantly wider range of patch widths conducive for experimental fabrication. We show that the crystallization in the two-component system is both thermodynamically and kinetically enhanced, as compared to the one-component system. Although our bottom-up route does not lead to the selection of the cubic polytype exclusively, we find that the cubicity of the self-assembled crystals increases with increasing patch width. Our designer system not only promises a scalable bottom-up route for colloidal diamond but also offers fundamental insight into crystallization into open lattices.

Effects of Composite Coatings Functionalized with Material Additives Applied on Textile Materials for Cut Resistant Protective Gloves.

The objective of the present work was to evaluate the effects of different types of particles added to a polymer paste applied onto a textile carrier on the cut resistance of the resulting material. Knitted aramid textile samples were coated in laboratory conditions using a polymer paste that was functionalized with 12 types of reinforcing particles of different chemical compositions and size fractions. Cut resistance was tested in accordance with the standard EN ISO 13997:1999 and the results were subjected to statistical analysis. The effects of additive particles on the microstructure of the polymeric layer were assessed by means of scanning electron microscopy. The type and size of the particles affected the cut resistance of the functionalized knitted fabric. They were also found to change the morphology of the porous structure. Composite coatings containing the smallest additive particles exhibited the best cut resistance properties.

Secondary reactions in the analysis of microplastics by analytical pyrolysis

Mixtures of plastic particles of different types were analysed by Py-GC-MS in order to investigate the effect of polymer interactions on the composition of pyrolysates. Pyrolysis products associated to secondary reactions were observed when particles of poly(ethylene terephthalate) (PET) were pyrolysed in the presence of poly(vinylchloride) (PVC) and the polyamides PA6 (polycaproamide) and PA66 (poly(hexamethylene adipamide)). Co-pyrolysis of PET in the presence of PVC particles produced mono and dichloroethyl esters of terephthalic acid due to the addition of HCl to the double bond of the vinyl group. Benzyl chloride, benzoyl chloride, 4-chlorobenzoic acid were also tentatively identified. The interaction between PET and PA6 and above all PA66 brought about the formation of aromatic nitriles including methyl and ethyl benzonitrile, 1,4-benzenedicarbonitrile, 4-cyanoethyl benzoate, 4-cyano benzoic acid. In addition, co-pyrolysis of PET and PA66 particles produced N-alkyl amides of benzoic acid. Pyrolysis of benzoic acid generated benzene and diphenyl, while N-hexylbenzamide was observed from the pyrolysis of benzoic acid with hexyl-1-amine or hexan-1,6-diamine. PE (polyethylene), PP (polypropylene), PS (polystyrene) and PVC did not exhibit significant interactions. Calibration curves built up with single plastic types in the 10–120 µg range were used to quantify each polymer in the mixture using typical pyrolytic markers. The highest deviations of recovery and the lowest RSD were observed for PET and PA6, while polyolefins produced satisfactory recovery and RSD. The detection of pyrolysis products from secondary reactions can be used as markers for the co-presence of different polymers supporting their identification.

Influence of particle properties and environmental factors on the performance of typical particle monitors and low-cost particle sensors in the market of China

The performance of particle measurements based on three types of principles, including tapered element oscillating microbalance (TEOM), beta attenuation monitor (BAM) and light scattering, were investigated with different types of particle (braize, arizona dust and polystyrene spheres), particle sizes (1.1, 2.0, 2.5 and 3.0 μm), and environmental factors (temperature, relative humidity and relatively high particle concentration). Specifically, two middle-cost monitors (LY, LL) and three low-cost sensors (PT, YT, SF) with light scattering were considered.Good correlations with gravimetric were all observed on three principle instruments with three particle types at laboratory tests, except for less concerned intercepts did not meet the requirements of standard HJ 653–2013. Particle properties showed negligible effect on the instrumental measurements based on BAM and TEOM, commonly as high-cost monitors. Interestingly, middle-cost monitors were found to be more sensitive to particle properties versus low-cost sensors using calibration dusts with various properties. Moreover, obvious impacts of particle sizes were observed for all tested light-scattering monitors and sensors. In addition, different trends of sensors measuring PM10/PM2.5/PM1.0 with the increase of particle sizes indicated the poor particle recognition of light scattering principle. Expectedly, poor correlations of sensors were observed in ambient experiments compared with laboratory experiments due to the effect of complex environmental factors. Relative humidity (RH) and temperature (T) were proposed to express synergistic effects on measurements by sensors. Meanwhile, poor correlation and zero drift of YT sensors after high particle concentration exposure experiments revealed high particle concentrations would result in the pollution of low-cost sensors due to the lack of self-cleaning function. In conclusion, to evaluate the performance of sensors for future standard instrumental developments more accurately, both indoor and outdoor assessments should be taken out. The data acquired in this study could provide information for future evaluation of the performance of particle monitors and sensors based on light scattering principle.

Pauli crystals in harmonic trap and on a sphere

We study configurations maximizing N-particle probability distributions of non-interacting particles obeying Fermi statistics as discussed in [1]. We consider two different types of particles' confinement: (i) trapping in a harmonic potential and (ii) constraining to the surface of a sphere. In such settings the most probable arrangements of particles correspond to characteristic geometric patterns resulting from the combined effect of confinement and the Pauli exclusion principle. We discuss the geometry of these optimal configurations as well as two different methods of extracting these shapes from a number of single shot pictures of the system. The post-selection method which does not assume a priori any information on the optimal configurations is illustrated in detail.

Properties of multitype subcritical branching processes in random environment

Abstract We study properties of a p-type subcritical branching process in random environment initiated at moment zero by a vector z = (z 1, .., z p ) of particles of different types. For p = 1 the class of processes we consider corresponds to the so-called strongly subcritical case. It is shown that the survival probability of this process up to moment n behaves as C(z)λ n for large n, where the parameters λ ∈ (0, 1) and C(z) ∈ (0, ∞) are explicitly described in terms of the characteristics of the process. We also demonstrate that the distribution of the number of particles of different types at moment n → ∞ (given its survival up to this moment) does not asymptotically depend on the number and types of particles initiated the process.

Nanoparticle Superlattices through Template-Encoded DNA Dendrimers.

The chemical interactions that lead to the emergence of hierarchical structures are often highly complex and difficult to program. Herein, the synthesis of a series of superlattices based upon 30 different structurally reconfigurable DNA dendrimers is reported, each of which presents a well-defined number of single-stranded oligonucleotides (i.e., sticky ends) on its surface. Such building blocks assemble with complementary DNA-functionalized gold nanoparticles (AuNPs) to yield five distinct crystal structures, depending upon choice of dendrimer and defined by phase symmetry. These DNA dendrimers can associate to form micelle-dendrimers, whereby the extent of association can be modulated based upon surfactant concentration and dendrimer length to produce a low-symmetry Ti5Ga4-type phase that has yet to be reported in the field of colloidal crystal engineering. Taken together, colloidal crystals that feature three different types of particle bonding interactions-template-dendron, dendrimer-dendrimer, and DNA-modified AuNP-dendrimer-are reported, illustrating how sequence-defined recognition and dynamic association can be combined to yield complex hierarchical materials.

Large Eddy Simulation of particle-laden flow over dunes

The particle-laden turbulent flow over a two-dimensional dune bathymetry is studied by means of Large Eddy Simulation (LES). The 4-way coupling regime for particle–particle and particle-flow interactions is applied and an appropriate empirical formula is used to estimate the bedload transport. The flow conditions correspond to river flow in laboratory scale at a Reynolds number equal to 17,500 with respect to the maximum water depth and bulk velocity. The dune-shaped bed is introduced within a Cartesian grid by means of the Immersed Boundary Method. A particle cloud consisting of spherical particles is released within the carrier fluid under the influence of the Stokes drag and gravity forces. Three different types of particles are examined: acrylic, glass and steel particles. The particle volume fraction is significant and a hard-sphere model is deployed to account for particle–particle collisions in a 4-way coupling regime. Closure parameters for the collision model have been adopted for each type of the examined particles, based on experimental works in literature. Results focus on the effect of the particle inertia on their kinematics, the velocity field and the shear stress along the dune bed which modifies bedload transport. Using the numerical simulations presented, it can be observed that when larger particle-to-fluid density ratios were examined, larger slip velocities between the fluid and particle phases were recorded.

Thermodynamic characteristics and mineral dissolution model of the H2O-CO2-CaCO3-Albite-SiO2 system in sedimentary basins

Diagenesis controls the formation, evolution, and distribution of deep-buried sandstone reservoirs in sedimentary basins. The essence of diagenesis is the transformation of substances between different phases (solid, gas and liquid phases) and the migration of materials transported by formation water. Fluids transport in deep-buried formations in sedimentary basins is generally slow, which lead the reaction system is in a near-equilibrium-to-equilibrium state. In this context, thermodynamics can be employed to calculate the solubility and characterize the occurrences of various minerals in different states, which can help reveal the genetic mechanism of secondary pores in the deep-buried rocks of sedimentary basins. In this study, we investigate the types and contents of particles in the aqueous solutions in the H2O-CO2-CaCO3-Albite-SiO2 system under different temperature and pressure conditions. Specifically, the Gibbs free energy of formation of minerals and gases are calculated based on the constant-pressure specific heat model; the apparent standard molal Gibbs free energy of different ions in fluids are computed using the HKF model; the equilibrium constants of different reactions are calculated according to the Gibbs function; the contents of different types of particles are computed based on the charge balance principle in the aqueous solution. The results show that the contents of various particles in the aqueous solution are mainly controlled by temperature and CO2 partial pressure, while they are rarely impacted by the total pressure. Different ions are demonstrated to have different responses to temperature changes. Specifically, types of Ca- and C-containing particles in the aqueous solution are closely related to temperature, while those of Al- and Si-rich particles are rarely changed as temperature varies. The CO2-rich fluid migration environment that results from hydrocarbon generation can be regarded as an open system for the dissolution of calcite, while it is a closed-to-semi-closed system for the dissolution of quartz and feldspar. The content of secondary pores is demonstrated to be determined by the solubility of various particles in the aqueous solution as well as the rate and duration of fluid migration, while the distribution patterns and ranges of secondary pores are controlled by responses of various particles in the solution to temperature and pressure changes.

Zein Colloidal Particles and Cellulose Nanocrystals Synergistic Stabilization of Pickering Emulsions for Delivery of β-Carotene.

In this study, we utilized different types of particles to stabilize β-carotene-loaded Pickering emulsions: spherical hydrophobic zein colloidal particles (ZCPs) (517.3 nm) and rod-shaped hydrophilic cellulose nanocrystals (CNCs) (115.2 nm). Either of the particles was incapable of stabilizing Pickering emulsions owing to their inappropriate wettability. When the mass ratio of ZCPs and CNCs was 1:4, the Pickering emulsion showed the best physical and photothermal stability. Compared to the ZCP-stabilized Pickering emulsion (9.29%), the retention rate of β-carotene in the Pickering emulsion costabilized by ZCPs and CNCs was increased to 60.23% after 28 days of storage at 55 °C. Confocal microscopy and cryoscanning electron microscopy confirmed that different types of particles could form a multilayered structure or induce the formation of an interparticle network. Furthermore, the complexation of ZCPs and CNCs delayed the lipolysis of the emulsion during in vitro digestion. The free fatty acid (FFA) release rate of Pickering emulsions in the small intestinal phase was reduced from 19.46 to 8.73%. Accordingly, the bioaccessibility of β-carotene in Pickering emulsions ranged from 9.14 to 27.25% through adjusting the mass ratio and addition sequence of distinct particles at the interface. The Pickering emulsion with the novel particle-particle complex interface was designed in foods and pharmaceuticals for purpose of enhanced stability, delayed lipolysis, or sustained nutrient release.

Macroscopic and microscopic hydrodynamic mixing of stratified suspensions.

We conducted numerical experiments to investigate the mixing of stratified suspensions containing different types of particles. We used a point-force two-way coupling method. We studied the mixing behavior of stratified suspensions and we discovered two types of mixing: microscopic (individual-particle-level) and macroscopic (vessel-scale) collective mixing. In addition, we examined the vertical mixing speed of the stratified suspension. We used a simple theoretical model to analyze the fingering settling velocity. Then we introduced a nondimensional number representing the difference in collectivities of the upper and lower suspensions while accounting for particle terminal velocities. We discovered that the proposed nondimensional parameter has a negative sign that distinguishes the mixing form of only microscopic individual-particle-level mixing and a positive value that predicts the speed of macroscopic collective mixing of stratified suspensions.