Experimental validation of modeling irregular particle shapes using DEM

Abstract The Small Ice Detector, version 2 (SID-2), High-performance Instrumented Airborne Platform for Environmental Research (HIAPER; SID-2H) was used to detect small ice particles in the early stages of ice formation in the high liquid water environment of tropical maritime cumulus clouds sampled during the Ice in Clouds Experiment—Tropical (ICE-T) field campaign. Its performance in comparison to other probes and the development of new corrections applied to the data are presented. The SID-2H detected small ice crystals among larger particles. It correctly identified water drops, and discriminated between round and irregular particle shapes in water-dominated clouds with errors less than 5%. Remaining uncertainties in the sensing volume and the volume over which coincidence of particles occurred, result in the data being used here in a qualitative manner to identify the presence of ice, and its habits and sizes.

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Beyond Janus Geometry: Characterization of Flow Fields Around Nonspherical Photocatalytic Microswimmers

10.33774/chemrxiv-2021-2kjrh ◽

2021 ◽

Author(s):

Sandra Heckel ◽

Clemens Bilsing ◽

Martin Wittmann ◽

Thomas Gemming ◽

Lars Büttner ◽

...

Keyword(s):

Surface Defects ◽

High Spatial Resolution ◽

Flow Fields ◽

Chemical Gradient ◽

Carrier Distribution ◽

Motion Mechanism ◽

Irregular Particle ◽

Measured Flow ◽

Particle Shapes

Catalytic microswimmers that move by a phoretic mechanism in response to a self-induced chemical gradient are often obtained by the design of spherical janus microparticles, which suffer from multi-step fabrication and low yields. Approaches such as irregular particle shapes, local excitation or intrinsic asymmetry are on the rise to facilitate manufacturing, but the effects on the generation of motion remain poorly understood. In this work, single crystalline BiVO4 microswimmers are presented that rely on a strict inherent asymmetry of charge-carrier distribution under illumination. The origin of the asymmetrical flow pattern is elucidated becauseof the high spatial resolution of measured flow fields around pinned BiVO4 colloids. As a result the flow from oxidative to reductive particle sides was confirmed. Distribution of oxidation and reduction reactions suggests a dominant self-electrophoretic motion mechanism with a source quadrupole as the origin of the induced flows. It is shown that the symmetry of the flow fields is broken by self-shadowing of the particles and synthetic surface defects that impact the photocatalytic activity of the microswimmers. The results demonstrate the complexity of symmetry breaking in nonspherical microswimmers and are leading the way towards understanding ofpropulsion mechanisms of phoretic colloids of various shapes.

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A Super-Clustering Approach for Fully Automated Single Particle Picking in Cryo-EM

Genes ◽

10.3390/genes10090666 ◽

2019 ◽

Vol 10 (9) ◽

pp. 666 ◽

Cited By ~ 6

Author(s):

Al-Azzawi ◽

Ouadou ◽

Tanner ◽

Cheng

Keyword(s):

Structure Determination ◽

Single Particle ◽

Signal To Noise Ratio ◽

Clustering Methods ◽

Signal To Noise ◽

Robust Detection ◽

Irregular Particle ◽

Clustering Approach ◽

Noise Ratio ◽

Particle Shapes

Structure determination of proteins and macromolecular complexes by single-particle cryo-electron microscopy (cryo-EM) is poised to revolutionize structural biology. An early challenging step in the cryo-EM pipeline is the detection and selection of particles from two-dimensional micrographs (particle picking). Most existing particle-picking methods require human intervention to deal with complex (irregular) particle shapes and extremely low signal-to-noise ratio (SNR) in cryo-EM images. Here, we design a fully automated super-clustering approach for single particle picking (SuperCryoEMPicker) in cryo-EM micrographs, which focuses on identifying, detecting, and picking particles of the complex and irregular shapes in micrographs with extremely low signal-to-noise ratio (SNR). Our method first applies advanced image processing procedures to improve the quality of the cryo-EM images. The binary mask image-highlighting protein particles are then generated from each individual cryo-EM image using the super-clustering (SP) method, which improves upon base clustering methods (i.e., k-means, fuzzy c-means (FCM), and intensity-based cluster (IBC) algorithm) via a super-pixel algorithm. SuperCryoEMPicker is tested and evaluated on micrographs of β-galactosidase and 80S ribosomes, which are examples of cryo-EM data exhibiting complex and irregular particle shapes. The results show that the super-particle clustering method provides a more robust detection of particles than the base clustering methods, such as k-means, FCM, and IBC. SuperCryoEMPicker automatically and effectively identifies very complex particles from cryo-EM images of extremely low SNR. As a fully automated particle detection method, it has the potential to relieve researchers from laborious, manual particle-labeling work and therefore is a useful tool for cryo-EM protein structure determination.

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Utilization of Desulfurized Ash as a Modifier in Fluoride Retention and Deacidification of Fluorgypsum

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.311-313.1510 ◽

2011 ◽

Vol 311-313 ◽

pp. 1510-1513

Author(s):

Xin Ya Yang ◽

Qi Wei Yang

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Flue Gas ◽

Ph Value ◽

Water Soluble ◽

Hydration Process ◽

Power Station ◽

Irregular Particle ◽

Particle Shapes ◽

Scanning Electron

In this paper, desulfurized ash was focused on modifying the properties of fluorgypsum and quicklime was as a reference. According to the results of water-soluble fluoride and pH value of fluorgypsum with modifiers, the optimal fluoride retention and deacidification effect was obtained by adding 1.5 % of quicklime, 5 % of desulfurized ash from power station (DA-PS) or 2 % of desulfurized ash from sintered flue gas (DA-SFG), respectively. The continuous hydration process of the cementitious pastes of fluorgypsum was investigated by scanning electron microscopy (SEM). The morphology of the gypsum crystals was of irregular particle shapes dispersing inside. In the later hydrating age, the distribution of pores became uniform, and the connection between the crystals overlapped more compact. Considered the modification effects on cementitious pastes, DA-PS could take place of quicklime to achieve the fluoride retention and deacidification of fluorgypsum.

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Drag Coefficients of Irregularly Shaped Particles in Newtonian Fluids

Sustainability ◽

10.3390/su13147517 ◽

2021 ◽

Vol 13 (14) ◽

pp. 7517

Author(s):

Owolabi Akanni ◽

Chunkai Fu ◽

Boyun Guo

Keyword(s):

Drag Coefficient ◽

Settling Velocity ◽

Drilling Fluid ◽

Drill Cuttings ◽

Drag Coefficients ◽

Irregular Particle ◽

Computational Fluid Dynamics Analysis ◽

Fluid Properties ◽

Drilling Operations ◽

Particle Shapes

An accurate prediction of the settling velocities of drill cuttings is essential in effectively designing, running, and optimizing drilling operations. If there is no reliable process for modelling the drag coefficient, the settling velocity cannot be obtained. In most current literature, particles are assumed to be spherical, which can be easily modelled. However, this assumption may lead to inaccurate results for other irregular particle shapes. This paper studies the transport behavior of irregular particles by modelling these shapes as variants of a bow shape, with a numerical simulation approach for their drag coefficients. The drilling fluid around the particle is water (Newtonian). The drag coefficients of the non-spherical particle (grouped into three sub-shapes) were modelled. In addition, the inlet velocity of the fluid is varied to show the effects on the shape drag coefficients. The results of the simulations were compared to experimental results carried out by other researchers. It was observed that as the particles became less streamlined, their drag coefficient increased. A sensitivity analysis was carried out to investigate the effects of fluid properties on the drag coefficient. The results were consistent and logical. The results showed that Computational Fluid Dynamics analysis provided a reliable estimation of the drag coefficient, which can help optimize the transport of drill cuttings during drilling operations.

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Influence of Pyrolysis Parameters Using Microwave toward Structural Properties of ZnO/CNS Intermediate and Application of ZnCr2O4/CNS Final Product for Dark Degradation of Pesticide in Wet Paddy Soil

ChemEngineering ◽

10.3390/chemengineering5030058 ◽

2021 ◽

Vol 5 (3) ◽

pp. 58

Author(s):

Tutik Setianingsih ◽

Danar Purwonugroho ◽

Yuniar Ponco Prananto

Keyword(s):

Rice Husk ◽

Paddy Soil ◽

Carbon Precursor ◽

Pesticide Degradation ◽

Sem Images ◽

Liquid Fertilizer ◽

X Ray ◽

Irregular Particle ◽

Pollution Problem ◽

Particle Shapes

Pesticide is a pollution problem in agriculture. The usage of ZnCr2O4/CNS and H2O2 as additive in liquid fertilizer has potency for catalytic pesticide degradation. Colloid condition is needed for easy spraying. Rice husk and sawdust were used as carbon precursor and ZnCl2 as activator. The biomass–ZnCl2 mixtures were pyrolyzed using microwave (400–800 W, 50 min). The products were dispersed in water by blending then evaporated to obtain ZnO/CNS. The composites were reacted with KOH, CrCl3·6H2O, more ZnCl2, and little water by microwave (600 W, 5 min). The ZnCr2O4/CNS and H2O2 were used for degradation of buthylphenylmethyl carbamate (BPMC) in wet deactivated paddy soil. TOC was measured using TOC meter. The FTIR spectra of the ZnO/CNS composites indicated the completed carbonization except at 800 W without ZnCl2. The X-ray diffractograms of the composites confirmed ZnO/CNS structure. SEM images showed irregular particle shapes for using both biomass. ZnCr2O4/CNS structure was confirmed by XRD as the final product with crystallite size of 74.99 nm. The sawdust produced more stable colloids of CNS and ZnO/CNS composite than the rice husk. The pyrolysis without ZnCl2 formed more stable colloid than with ZnCl2. The ZnCr2O4/CNS from sawdust gave better dark catalytic degradation of BPMC than from rice husk, i.e., 2.5 and 1.6 times larger for 400 and 800 W pyrolysis, respectively.

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