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Number of results: 117
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Abstract

Deposition of aerosols in the respiratory tracts depends on their size distribution. Investigation of such distribution has therefore great meaning lor appropriate assessment o frisk caused by hazardous pollutants that appear in environment both as a result of human activities like industry, emission from motor vehicles. municipal emission due to house furnaces and natural phenomena. The results or screening measurements or size distribution performed in several places located on highly populated areas in Upper Silesia, Poland arc described in this paper. The applied equipment makes it possible to cover the range from several nanometers up to 20 rim, practically all particles that belong to the rcspirable class. Obtained results prove that a lot of particles having a size of the order or submicrons are produced close lo high density tra Ilic roads. This concentration strongly changed in time.
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Authors and Affiliations

Krystian Skubacz
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Abstract

Widely used CFD codes enable modelling of PC boilers operation. One of the areas where these numerical simulations are especially promising is predicting deposition on heat transfer surfaces, mostly superheaters. The basic goal of all simulations is to determine trajectories of ash particles in the vicinity of superheater tubes. It results in finding where on the surface the tube will be hit by particles, and what diameter and mass flow of the particles are. This paper presents results of CFD simulations for a single tube and a bundle of in-line tubes as well. It has been shown that available parameters like ash particle density, shape factor, reflection coefficients affect the trajectories in a different way. All the simulations were carried out with Fluent code of Ansys software.

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Authors and Affiliations

Krzysztof Wacławiak
Sylwester Kalisz
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Abstract

Transport properties of bronchial mucus are investigated by two-stage experimental approach focused on: (a) rheological properties and (b) mass transfer rate through the stagnant layer of solutions of mucus components (mucine, DNA, proteins) and simulated multi-component mucus. Studies were done using thermostated horizontal diffusion cells with sodium cromoglycate and carminic acid as transferred solutes. Rheological properties of tested liquids was studied by a rotational viscometer and a cone-plate rheometer (dynamic method). First part of the studies demonstrated that inter-molecular interactions in these complex liquids influence both rheological and permeability characteristics. Transfer rate is governed not only by mucus composition and concentration but also by hydrophobic/hydrophilic properties of transported molecules. Second part was focused on the properties of such a layer in presence of selected nanostructured particles (different nanoclays and graphene oxide) which may be present in lungs after inhalation. It was shown that most of such particles increase visco-elasticity of the mucus and reduce the rate of mass transfer of model drugs. Measured effects may have adverse impact on health, since they will reduce mucociliary clearance in vivo and slow down drug penetration to the bronchial epithelium during inhalation therapy.

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Authors and Affiliations

Marcin Odziomek
Martyna Kalinowska
Aleksandra Płuzińska
Antoni Rożeń
Tomasz R. Sosnowski
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Abstract

Stability of silver nanoparticles strongly influences the potential of their application. The literature shows wide possibilities of nanoparticles preparation, which has significantly impact on their properties. Therefore, the improvement of AgNPs preparation plays a key role in the case of their practical use. The pH values of the environment are one of the important factors, which directly influences stability of AgNPs. We present a comparing study of the silver nanoparticles prepared by „bottom-up“ methods over by chemical synthesis and biosynthesis using AgNO3 (0.29 mM) solution. For the biosynthesis of the silver nanoparticles, the green freshwater algae Parachlorella kessleri and Citrus limon extracts were used as reducing and stabilizing agents. Chemically synthesized AgNPs were performed using sodium citrate (0.5%) as a capping agent and 0.01% gelatine as a reducing agent. The formation and long term stability of those silver nanoparticles synthesized either biologically and chemically were clearly observed by solution colour changes and confirmed by UV-vis spectroscopy. The pH values of formed nanoparticle solutions were 3 and 5.8 for biosynthesized AgNPs using extract of Citrus limon and Parachlorella kessleri, respectively and 7.2 for chemically prepared AgNPs solution using citrate. The SEM as a surface imaging method was used for the characterization of nanoparticle shapes, size distribution and also for resolving different particle sizes. These micrographs confirmed the presence of dispersed and aggregated AgNPs with various shapes and sizes.
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Authors and Affiliations

O. Velgosová
A. Mražíková
J. Kavuličová
M. Matvija
E. Čižmárová
J. Willner
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Abstract

The paper presents results of compressive strength investigations of EN AC-44200 based aluminum alloy composite materials reinforced

with aluminum oxide particles at ambient and at temperatures of 100, 200 and 250C. They were manufactured by squeeze casting of the

porous preforms made of α-Al2O3 particles with liquid aluminum alloy EN AC-44200. The composite materials were reinforced with

preforms characterized by the porosities of 90, 80, 70 and 60 vol. %, thus the alumina content in the composite materials was 10, 20, 30

and 40 vol.%. The results of the compressive strength of manufactured materials were presented and basing on the microscopic

observations the effect of the volume content of strengthening alumina particles on the cracking mechanisms during compression at

indicated temperatures were shown and discussed. The highest compressive strength of 470 MPa at ambient temperature showed

composite materials strengthened with 40 vol.% of α-Al2O3 particles.

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Authors and Affiliations

A. Kurzawa
J.W. Kaczmar
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Abstract

The paper concerns simulation of fully developed and axially-symmetrical turbulent flow of coarse-dispersive slurry if all solid particles have similar size and shape with particles diameter from 1 mm to 5 mm, solid density from 1045 kg/m^3 to 3000 kg/m^3, and solid concentration by volume from 20% to 40%. The author examines the influence of particle diameter on additional shear stress due to the ‘particles-wall’ interactions for moderate and high solid concentration. The mathematical model was developed using Bagnold's concept, [26] and assumes that the total wall shear stresses are equal to the sum of ‘liquid-wall’ and ‘particles-wall’ shear stresses. The mathematical model was successfully verified with own measurements of frictional head loss in vertical coarse - dispersive slurry flow, named: ‘sand-water’, ‘polystyrene-water’ and ‘pvc-water’, [10], [26]. The mathematical model can predict ‘particles-wall’ shear stress, pressure drop and friction factor for coarse-dispersive turbulent slurry flow in a pipe, [10].

The aim of the paper is to present qualitative and quantitative dependence of solid particle diameter, solid particle density, solid concentration, and Reynolds number for carrier liquid phase on the ‘particles-wall’ shear stress. It is demonstrated that the solid particle diameter plays crucial role in its dependence on the ‘particles-wall’ shear stress. It was proved that in particular flow conditions the ‘particles-wall’ shear stress is much higher compared to the carrier liquid wall shear stress.

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Authors and Affiliations

Artur Bartosik
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Abstract

The presented work deals with the influence of the addition of soft graphite particles on the abrasive wear of composite reinforced with

hard SiC particles. The discussed hybrid composites were produced by stirring the liquid alloy and simultaneous adding the mixture of

particles. The adequately prepared suspension was gravity cast into a metal die. Both the composite castings obtained in this way and the

comparative castings produced of the pure matrix alloy were examined for the abrasive wear behaviour. Photomacrographs of the sliding

surfaces of the examined composites were taken, and also the hardness measurements were carried out. It was found that even a small

addition of Cgr particles influences positively the tribological properties of the examined composite materials, protecting the abraded

surface from the destructive action of silicon carbide particles. The work presents also the results of hardness measurements which confirm

that the composite material hardness increases with an increase in the volume fraction of hard reinforcing particles.

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Authors and Affiliations

Z. Konopka
M. Łągiewka
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Abstract

The process of enrichment in a jig has usually been described and analysed using particle density as a separation feature. However, a degree of particle loosening in the jig bed is affected by, inter alia, the terminal particle free settling velocity which in turn is affected by the size, density and shape of a particle. Therefore, the terminal particle settling velocity clearly characterises the feed transferred to a jig for the enrichment process. Taking the comprehensive particle geometric (particle size and shape) and physical properties (particle density) into account comes down to the calculation of the terminal particle settling velocity. The terminal particle settling velocity is therefore a complex separation feature which comprises three basic particle features (particle density, size and shape). This paper compares the effects of enrichment of coal fines in a jig, for two cases: when the commonly applied particle density is separation feature and for the particle settling velocity. Particle settling velocities were calculated in the selected three particle size fractions: –3.15+2.00, –10.00+8.00 and –20.00+16.00 mm based on the industrial testing of a jig for coal fines and detailed laboratory tests consisting in determining particle density, projective diameter and volume and dynamic particle shape coefficient. The calculated and drawn partition curves for two variants, i.e. when particle density and particle settling velocity were taken into account as the separation argument in selected particle size fractions, allowed to calculate and compare separation precision indicator. With the use of a statistical test, the assumption on the independence of random variables of the distribution of components included in the distribution of the particle settling velocity as a separation feature during enrichment in a jig was verified.

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Authors and Affiliations

Agnieszka Surowiak
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Abstract

This article is devoted to the German classes of particles: Gradpartikel (degree particle) and Fokuspartikel (focus particle), which are assigned divergent contents in different grammars and lexicons. In addition to this, a problem with didactic implications is the inconsistency of terminology. For example, Helbig/Buscha (2001) apply the term Gradpartikel to expressions that Hentschel/Weydt (2013) classify as Fokuspartikel. Engel (2009), on the other hand, refers to the expressions as Gradpartikel, which in Hentschel/Weydt (2013) represent the classes Fokuspartikel and Intensivpartikel. There are more similar inconsistencies in the literature with regard to class names and the inclusion of particles within them. The aim of this article is to revise the classification criteria and analyse the distinguishing characteristics of these classes and to put the terminology in order. The choice of terms in this article was determined by the primary function of the class: Fokuspartikel is named according to the function of focusing attention on something (German: fokussieren), while Gradpartikel is named according to the function of reinforcing (German: gradieren).
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Authors and Affiliations

Edyta Błachut
1

  1. Universität Wrocław
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Abstract

The article presents the results of research aimed at increase of the efficiency of gas cleaning equipment based on the Venturi tube using high-intensity ultrasound. The model based on known laws of hydrodynamics of multiphase mediums of dust-extraction in Venturi scrubbers was proposed. Modification of this model taking into account ultrasonic field allows evaluating optimum modes (sound pressure level) and conditions (direction of ultrasonic field, square and number of ultrasonic sources) of ultrasonic influence. It is evaluated that optimum for efficient gas cleaning is the mode of ultrasonic action at the frequency of 22 kHz with sound pressure level of 145. . . 155 dB at the installation of two radiators with area of 0.14 m2, four radiators with area of 0.11 m2 or six radiators with area of 0.08 m2 at the angle of 45 degrees to the axis of Venturi tube. Numerical calculations showed that realization of ultrasonic action is the most efficient for the reduction (up to 15 times) of the content of fine-dispersed fraction (2 μm and less), which is impossible to extract without ultrasonic action. The received theoretical results were confirmed by industrial testing by typical dust-extraction plant and used as foundations of development of apparatuses with the radiators of various sizes.

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Authors and Affiliations

Vladimir N. Khmelev
Andrey V. Shalunov
Roman N. Golykh
Roman S. Dorovskikh
Viktor A. Nesterov
Sergey S. Khmelev
Ksenija V. Shalunova
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Abstract

The paper presents the summary of research on polymer melt particle motion trajectories in a disc zone of a screw-disk extruder. We analysed two models of its structure, different in levels of taken simplifications. The analysis includes computer simulations of material particle flow and results of experimental tests to determine the properties of the resultant extrudate. Analysis of the results shows that the motion of melt in the disk zone of a screw-disk extruder is a superposition of pressure and dragged streams. The observed trajectories of polymer particles and relations of mechanical properties and elongation of the molecular chain proved the presence of a stretching effect on polymer molecular chains.

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Authors and Affiliations

Tomasz Rydzkowski
Iwona Michalska-Pożoga
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Abstract

The paper presents results of bend tests at elevated temperatures of aluminium alloy EN AC-44200 (AlSi12) based composite materials

reinforced with aluminium oxide particles. The examined materials were manufactured by squeeze casting. Preforms made of Al2O3

particles, with volumetric fraction 10, 20, 30 and 40 vol.% of particles joined with sodium silicate bridges were used as reinforcement. The

preforms were characterised by open porosity ensuring proper infiltration with the EN AC-44200 (AlSi12) liquid alloy. The largest

bending strength was found for the materials containing 40 vol.% of reinforcing ceramic particles, tested at ambient temperature. At

increased test temperature, bending strength Rg of composites decreased in average by 30 to 50 MPa per 100°C of temperature increase.

Temperature increase did not significantly affect cracking of the materials. Cracks propagated mainly along the interfaces particle/matrix,

with no effect of the particles falling-out from fracture surfaces. Direction of cracking can be affected by a small number of

agglomerations of particles or of non-reacted binder. In the composites, the particles strongly restrict plastic deformation of the alloy,

which leads to creation of brittle fractures. At elevated temperatures, however mainly at 200 and 300°C, larger numbers of broken,

fragmented particles was observed in the vicinity of cracks. Fragmentation of particles occurred mainly at tensioned side of the bended

specimens, in the materials with smaller fraction of Al2O3 reinforcement, i.e. 10 and 20 vol.%.

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Authors and Affiliations

A. Kurzawa
J.W. Kaczmar
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Abstract

In this paper, crushability of foundry sand particles was studied. Three kinds of in-service silica sands in foundry enterprises selected as the study object, and foundry sand particles were subjected to mechanical load and thermal load during service were analyzed. A set of methods for simulating mechanical load and thermal load by milling and thermal-cold cycling were designed and researched, which were used to characterize the crushability for silica sand particles, the microstructure was observed by SEM. According to the user’s experience in actual application, the crushability of Sand C was the best and then Sand B, the last Sand A. The results indicated that mechanical load, thermal load and thermal-mechanical load can all be used to characterize the crushability of foundry sand particles. Microscopic appearances can qualitatively characterize the crushability of foundry sand particles to a certain extent, combining with the additions and cracks which are observed on the surface.

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Authors and Affiliations

Yui Da
Quan-yang Ma
Xiao-hua Li
Xi Zhang
Fa-ping Hu
Yun Zhang
Wei-dong Xie
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Abstract

The paper presents the results of research of impact strength of aluminum alloy EN AC-44200 based composite materials reinforced with

alumina particles. The research was carried out applying the materials produced by the pressure infiltration method of ceramic preforms

made of Al2O3 particles of 3-6m with the liquid EN AC-44200 Al alloy. The research was aimed at determining the composite resistance

to dynamic loads, taking into account the volume of reinforcing particles (from 10 to 40% by volume) at an ambient of 23°C and at

elevated temperatures to a maximum of 300°C. The results of this study were referred to the unreinforced matrix EN AC-44200 and to its

hardness and tensile strength. Based on microscopic studies, an analysis and description of crack mechanics of the tested materials were

performed. Structural analysis of a fracture surface, material structures under the crack surfaces of the matrix and cracking of the

reinforcing particles were performed.

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Authors and Affiliations

A. Kurzawa
J.W. Kaczmar
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Abstract

In this study, silicon carbide (SiC) reinforced lead-free solder (SAC305) was prepared by the powder metallurgy method. In this method SAC305 powder and SiC powder were milled, compressed and sintered to prepare composite solder. The composite solders were characterized by optical and scanning electron microscopy for the microstructural investigation and mechanical test. Addition of 1.5 wt. % and 2 wt. % ceramic reinforcement to the composite increased compressive strengths and microhardness up to 38% and 68% compared to those of the monolithic sample. In addition, the ceramic particles caused an up to 55% decrease in the wetting angle between the substrate and the composite solder and porosity was always increased with increase of SiC particles.

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Authors and Affiliations

Manoj Kumar Pal
G. Gergely
D. Koncz-Horvath
Z. Gacsi
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Abstract

In this study, ODS ferritic stainless steels were fabricated using a commercial alloy powder, and their microstructures and mechanical properties were studied to develop the advanced structural materials for high temperature service applications. Mechanical alloying and uniaxial hot pressing processes were employed to produce the ODS ferritic stainless steels. It was revealed that oxide particles in the ODS stainless steels were composed of Y-Si-O, Y-Ti-Si-O, and Y-Hf-Si-O complex oxides were observed depending on minor alloying elements, Ti and Hf. The ODS ferritic stainless steel with a Hf addition presented ultra-fine grains with uniform distributions of fine complex oxide particles which located in grains and on the grain boundaries. These favorable microstructures led to superior tensile properties than commercial stainless steel and ODS ferritic steel with Ti addition at elevated temperature.

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Authors and Affiliations

Sanghoon Noh
Suk Hoon Kang
Tae Kyu Kim
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Abstract

The agglomeration of particles is a process that modifies the physical properties of a product originally manufactured as a powder. During milk powder agglomeration of fluidized bed, resulting agglomerates are sufficiently porous to improve the solubility of the final product but, at the same time, their rigidity decreases and agglomerates can be destroyed during packing. The porosity and rigidity properties depend on both the volume and shape characteristics of the agglomerates. This paper presents a three-dimensional reconstruction technique based on a laser displacement sensor (LDS) applied to characterize milk agglomerates. This technique allows three-dimensional scanning to estimate particle volume and extract shape parameters such as: sphericity, elongation and flatness ratio, shape factor and aspect ratio. This technique was implemented using a mechatronic device with two degrees of freedom. The device is composed of an angular positioning system to rotate the agglomerate and a linear positioning system to displace the LDS. Experimental result allows agglomerates classification according to shape parameters

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Authors and Affiliations

J. P. Zavala De Paz
E. Castillo Castañeda
J. Soto Herrera
C. Turchiuli
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Abstract

This study analyzes the conditional structures in the Spoken Arabic of Siirt, focusing on a series of aspects such as the topic of the sentences in such syntactical structures, the conditional markers, the verbal patterns and preverbal particles employed for introducing the conditionals and a compositional analysis of the conditional clause, with focus on the distinction between the real, open, generic, habitual and hypothetical conditionals, among other known types of the structure under study.

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Authors and Affiliations

Gabriel Bițună
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Abstract

To investigate the impact of various Al-Ti-B grain-refiners on solidification and grain-refining performance, a wrought aluminium alloy AA6182 was used. Three different grain-refiners from different manufacturers were used to establish the efficiency, i.e. contact time before casting, on the primary solidification and grain formation size. The primary solidification of α-Al grains at inoculation was observed by using thermal analysis (TA). Differential scanning calorimetry (DSC) was used in order to analyze the quality of various grain-refiners. The size of the primary grains was analyzed using optical microscopy (OM). Scanning electron microscopy (SEM) was used to estimate the size and distribution of Al3Ti and TiB2 particles in various grain-refiners and to establish the best efficiency of the investigated grain-refiners.

Within 1-4 min of inoculation the smallest fine equiaxed grains were achieved when either one of the investigated grain-refiners was added. It was established, that grain-refiner A contains higher content of impurities which do not melt in the experimental temperature range made by DSC method. The most pure grain-refiner turned out to be grain-refiner B, in which the most optimal number of TiB2 particles and particle size distribution was found.

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Authors and Affiliations

M. Vončina
J. Medved
L. Jerina
I. Paulin
P. Cvahte
M. Steinacher
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Abstract

One of the concepts of the ventilation rate control in buildings with dense and unpredictable occupancies is based on the CO2 measurements. There are many limitations regarding the validity of CO2 measurement inputs as suitable to the ventilation rate control. Verifying research has been conducted in an air-conditioned auditorium, in the real conditions at altered ventilation air thermal parameters and variable occupancy. The CO2 and the number concentrations of the fine and coarse aerosol particles(> 0.3 μm) and bioaerosol particles (bacteria and staphylococci) as well as the indoor air thermal parameters were measured in the individual sectors of the occupied area. The sensory assessments and instrumental determinations of the acceptability of indoor air quality (ACC) were also performed. The ventilation control strategy based, apart from the CO2 measurements, on the continuous monitoring of the perceived air quality (PAQ) in the auditorium sectors has been suggested. The PAQ monitoring could be accomplished by aerosol concentration measurements and the ACC instrumental determinations. This strategy should ensure a desired PAQ in sectors which benefit the occupants' comfort, health and productivity as well as energy savings not only in the case of its implementation in the considered auditorium.
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Authors and Affiliations

Bernard Połednik
Marzenna Dudzińska
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Abstract

This work presents the development of a safer processing route for hard metals. Traditional processing of fine particles under organic solvents presents significant explosion risks. The milling under dichloromethane (DCM) reduces the risks associated with fire hazards. After milling and drying, the samples have been sintered in an industrial sintering furnace under a vacuum at 1380°C. The materials’ characterisation has been done by X-ray diffraction, scanning electron microscopy, particle size analysis, optical microscopy, and by magnetic measurements. The present work results reveal the powders’ appropriate properties after milling and drying and the desired biphasic (Co-WC) phases obtained after sintering, thus proving the feasibility of such a route, therefore the diminishing of specific fire hazards.
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Authors and Affiliations

H.-F. Chicinaș
1 2
ORCID: ORCID
O.-D. Jucan
1
ORCID: ORCID
R.V. Gădălean
1 2
ORCID: ORCID
G. Conțiu
1 2
ORCID: ORCID
A. Cotai
1
ORCID: ORCID
C.O. Popa
1
ORCID: ORCID

  1. Technical University of Cluj-Napoca, Materials Science and Engineering Department, 103-105 Muncii Avenue, 400641 Cluj-Napoca, Romania
  2. Gühring Romania, 32 Constructorilor Street, 407035 Apahida, Romania
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Abstract

Fixed beds were adopted for removal of organic dye from water by photocatalytic decomposition or adsorption. To this end, macroporous titania or silica micro-particles were synthesized from emulsions as micro-reactors and packed in the bed. During feeding aqueous methylene blue solution, UV light was irradiated for generation of active radicals for removal of dye by photocatalytic decomposition. Porous silica particles were also used as adsorbents in the bed for continuous adsorption of organic dye. For regeneration of the porous titania or silica particles, rinsing with fresh water was carried out before repeated cycles.
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Authors and Affiliations

Young-Sang Cho
1
ORCID: ORCID
Sohyeon Sung
1
ORCID: ORCID

  1. Tech University of Korea, Department of Chemical Engineering and Biotechnology, 15073, 237 Sangidaehak-ro, Siheung-si, Korea
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Abstract

Porcine circovirus type 2 (PCV2) is an economically important swine pathogen and, although small, it has the highest evolution rate among DNA viruses. Commercial PCV2 commercial vaccines are inactivated PCV2 isolates or a subunit vaccine based on the Cap protein of PCV2. Currently, PCV2 VLPs of individual subtype vaccines are available. Although the main prevalent genotype worldwide is PCV2b, the emerging subtype PCV2d subtype is also increasingly associated with PCV disease. The aim of the study was to evaluate the protective efficacy of VLP based on the PCV2b and 2d subtypes against the mixed challenge of two hypotype PCV2 in mice. Thirty-six female SPV Kunming mice were immunized twice with PCV2b and 2d VLPs, then challenged with PCV2b and PCV2d, to assess the immunogenicity and effectiveness of the VLPs. Vaccination of the mice with PCV2b and 2d VLPs elicited a robust antibody response specific for the PCV2. The virus load detected in the 2b and 2d spleen vaccine group was the lowest compared to other groups. Furthermore, there was no pathological damage in the HE stained sections of the 2b and 2d spleen vaccine, and no virus was detected in the immunohistochemical sections. Our data suggest that the mixed PCV2b and 2d VLP vaccine could protect mice from challenge with the mixed infection of PCV2b and PCV2d.
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Authors and Affiliations

X.M. Yuan
1
Q.C. Yuan
1
S.M. Feng
1
Z.B. Deng
1

  1. Laboratory of Animal Disease Prevention and Control and Animal model, Hunan Provincial Key Laboratory of Protein Engineering in Animal Vaccines, College of Veterinary Medicine, Hunan Agricultural University, No. 1 Nongda road, Furong District, Changsha, 410128, People’s Republic of China
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Abstract

The objective of this work is to gain a deeper understanding of the separation effects and particle movement during filtration of non-metallic inclusions in aluminum casting on a macroscopic level. To understand particle movement, complex simulations are performed using Flow 3D. One focus is the influence of the filter position in the casting system with regard to filtration efficiency. For this purpose, a real filter geometry is scanned with computed tomography (CT) and integrated into the simulation as an STL file. This allows the filtration processes of particles to be represented as realistically as possible. The models provide a look inside the casting system and the flow conditions before, in, and after the filter, which cannot be mapped in real casting tests. In the second part of this work, the casting models used in the simulation are replicated and cast in real casting trials. In order to gain further knowledge about filtration and particle movement, non-metallic particles are added to the melt and then separated by a filter. These particles are then detected in the filter by metallographic analysis. The numerical simulations of particle movement in an aluminum melt during filtration, give predictions in reasonable agreement with experimental measurements.
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Authors and Affiliations

B. Baumann
1
A. Keßler
1
E. Hoppach
1
G. Wolf
1
M. Szucki
1
ORCID: ORCID
O. Hilger
2

  1. Foundry Institute, Technische Universität Bergakademie Freiberg, 4 Bernhard-von-Cotta-Str., 09599 Freiberg, Germany
  2. Simcast GmbH, Westring 401, 42329 Wuppertal, Germany

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