scholarly journals The mixing of cohesive and flowable powder materials using a common laboratory powder mixer

Food Research ◽  
2021 ◽  
Vol 5 (S1) ◽  
pp. 19-24
Author(s):  
Mohd Radzuan N. ◽  
Anuar M.S. ◽  
S.M. Tahir
Keyword(s):  
Rotational Speed ◽  
Mixing Time ◽  
Powder Materials ◽  
Mixing Process ◽  
Experimental Conditions ◽  
Powder Bed ◽  
Powder Mass ◽  
Cohesive Powder ◽  
Mixture Homogeneity ◽  
Common Laboratory

This study presented the homogeneity obtained when mixing cohesive and flowable powder materials using a laboratory powder mixer. The mixing process parameters studied were the mixing time and the mixer rotational speed (20 rpm, 40 rpm and 60 rpm) at the different ratios (95%: 5%, 50%: 50% and 5%: 95%) of the cohesive cocoa and flowable mannitol powder materials. The homogeneity sampled at the powder bed surface showed that only at the highest rotational speed of 60 rpm used in this work yield acceptable homogeneity at the two extremes of the powder mass ratios; 95%: 5% and 5%: 95% of mannitol: cocoa for some of the locations on the powder bed surface, especially near the wall of the mixer. Other combinations of the experimental conditions did not yield acceptable mixture homogeneity. These results showed the difficulties in obtaining a homogeneous powder mix when mixing cohesive powder materials, especially in academic teaching and research laboratories using a simple powder mixer apparatus.

Relationship between processing and electrical properties in SEBS/CNT nanocomposites

2016 ◽  
Vol 49 (4) ◽  
pp. 356-367 ◽  
Author(s):  
Paulina Latko ◽  
Mateusz Bielecki ◽  
Rafał Kozera ◽  
Anna Boczkowska
Keyword(s):  
Electrical Conductivity ◽  
Rotational Speed ◽  
Triblock Copolymer ◽  
Mixing Time ◽  
Processing Temperature ◽  
Mixing Process ◽  
Melt Mixing ◽  
Multiwalled Carbon ◽  
The Relationship ◽  
Selection Of

This article describes nanocomposites of triblock copolymer styrene–ethylene/butylene–styrene doping with 5 wt% of multiwalled carbon nanotubes (CNTs) prepared by melt mixing process. The selection of processing temperature was made according to the state of macrodispersion of CNTs within polymer matrix. Afterwards, the relationship between rotational speed, mixing time and electrical conductivity has been noted. It was confirmed that the temperature of 300°C and rotational speed of 100 r/min lead to significant decreasing of CNT agglomerations resulting in high electrical conductivity equal to 8.0 S/m.

scholarly journals Formation conditions and mechanical properties of aggregates produced in tephra–water–snow flows

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Hirofumi Niiya ◽  
Kenichi Oda ◽  
Daisuke Tsuji ◽  
Hiroaki Katsuragi
Keyword(s):  
Mechanical Properties ◽  
Mixing Time ◽  
Testing Machine ◽  
Small Scale ◽  
Scaling Analysis ◽  
Compression Tests ◽  
Ice Slurry ◽  
Experimental Conditions ◽  
Formation Conditions ◽  
Snow And Ice

Abstract The formation of aggregates consisting of snow, water, and tephra has been reported in small-scale experiments on three-phase flows containing tephra, water, and snow, representing lahars triggered by snowmelt. Such aggregates reduce the mobility of mud flow. However, the formation mechanism of such aggregates under various conditions has not been investigated. To elucidate the formation conditions and mechanical properties of the aggregates, we performed mixing experiments with materials on a rotating table and compression tests on the resulting aggregates with a universal testing machine in a low-temperature room at $$0\,^{\circ }\text {C}$$ 0 ∘ C . From experiments with varying component ratios of the mixture and tephra diameter, the following results were obtained: (i) the aggregate grew rapidly and reached maturity after a mixing time of 5 min; (ii) the mass of aggregates increased with snow concentration, exhibiting an approximately linear relationship; (iii) single aggregates with large mass formed at lower and higher tephra concentrations, whereas multiple aggregates with smaller mass were observed at intermediate concentrations; (iv) the shape of the aggregate satisfied the similarity law for an ellipsoid; (v) the compressive mechanical behavior could be modeled by an empirical nonlinear model. The obtained mechanical properties of the aggregates were independent of the experimental conditions; (vi) scaling analysis based on the Reynolds number and the strength of the aggregates showed that the aggregates cannot form in ice-slurry lahars. Our findings suggest that low-speed lahars containing snow and ice are likely to generate aggregates, but snow and ice in the ice-slurry lahars are dispersed without such aggregates.

scholarly journals The life history of Hepatozoon leptodactyli (Lesage, 1908) Pessoa, 1970: a parasite of the common laboratory animal: the frog of the genus Leptodactylus

1973 ◽  
Vol 71 (1-2) ◽  
pp. 1-8 ◽  
Author(s):  
Sylvio Celso Goncalves da Costa ◽  
Samuel B. Pessoa ◽  
Neize de Moura Pereira ◽  
Tania Colombo
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Life History ◽  
Laboratory Animal ◽  
Peripheral Circulation ◽  
Experimental Conditions ◽  
History Of ◽  
The Central Nervous System ◽  
The Common ◽  
Common Laboratory

The main object of the present paper is to furnish a brief account to the knowledgement of Protozoa parasitic in common Brazilian frog of the genus Leptodactylus for general students in Zoology and for investigators that use this frog as a laboratory animal. Hepatozoon leptodactyli (Haemogregarina leptodactyli) was found in two species of frogs - Leptodactylus ocellatus and L. pentadactylus - in which develop schizogony whereas sporogony occurs in the leech Haementeria lutzi as was obtainded in experimental conditions. Intracellular forms have been found in peripheral circulation, chiefly in erythrocytes, but we have found them in leukocytes too. Tissue stages were found in frog, liver, lungs, spleen, gut, brain and heart. The occurence of hemogregarine in the Central Nervous System was recorded by Costa & al,(13) and Ball (2). Some cytochemical methods were employed in attempt to differentiate gametocytes from trophozoites in the peripheral blood and to characterize the cystic membrane as well. The speorogonic cycle was developed in only one specie of leech. A brief description of the parasite is given.

scholarly journals Прямой магнитоэлектрический эффект в двухслойных керамических композитах на основе ферримагнетика Mn-=SUB=-0.4-=/SUB=-Zn-=SUB=-0.6-=/SUB=-Fe-=SUB=-2-=/SUB=-O-=SUB=-4-=/SUB=- и сегнетоэлектрика PbZr-=SUB=-0.53-=/SUB=-Ti-=SUB=-0.47-=/SUB=-O-=SUB=-3-=/SUB=-

2021 ◽  
Vol 63 (7) ◽  
pp. 888
Author(s):  
А.В. Калгин
Keyword(s):  
Magnetoelectric Effect ◽  
Powder Materials ◽  
Heterogeneous Environment ◽  
Effective Parameters ◽  
Experimental Conditions ◽  
Good Agreement

Under different experimental conditions, the direct magnetoelectric effect was studied in two-layer composites prepared both by joint sintering of layers of powders of ferrimagnet Mn0.4Zn0.6Fe2O4 and ferroelectric PbZr0.53Ti0.47O3 and by gluing plates pre-sintered from powder materials of Mn0.4Zn0.6Fe2O4 and PbZr0.53Ti0.47O3. It was found that sintered composites show greater values of the magnetoelectric effect than composites prepared by gluing sintered plates together. The revealed regularities are in good agreement with the conclusions from the theoreti-cal model of the effective parameters of the heterogeneous environment.

scholarly journals Application of Solid Dispersion Technique to Improve Solubility and Sustain Release of Emamectin Benzoate

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4315
Author(s):  
Bin Bin Huang ◽  
Dong Xu Liu ◽  
De Kun Liu ◽  
Gang Wu
Keyword(s):  
Solid Dispersion ◽  
Rotational Speed ◽  
Mixing Time ◽  
Solid Dispersions ◽  
Aqueous Solubility ◽  
Feed Ratio ◽  
Emamectin Benzoate ◽  
Wettable Powder ◽  
Dispersion Technique ◽  
Pvp K30

The solid dispersion technique, which is widely used in the medical field, was applied to prepare a pesticide dosage form of emamectin benzoate (EM). The preparation, physicochemical characterization, aqueous solubility, release dynamics, photolytic degradation, bioactivity, and sustained-release effects of the prepared EM solid dispersions were studied by a solvent method, using polymer materials as the carriers. Water-soluble polyvinyl pyrrolidone (PVP) K30 and water-insoluble polyacrylic resin (PR)III were used as the carriers. The influence of various parameters, such as different EM:PVP-K30 and EM:PRIII feed ratios, solvent and container choices, rotational speed and mixing time effects on pesticide loading, and the entrapment rate of the solid dispersions were investigated. The optimal conditions for the preparation of EM-PVP-K30 solid dispersions required the use of methanol and a feed ratio between 1:1 and 1:50, along with a rotational speed and mixing time of 600 rpm and 60 min, respectively. For the preparation of EM-PRIII solid dispersions, the use of methanol and a feed ratio between 1:4 and 1:50 were required, in addition to the use of a porcelain mortar for carrying out the process. Under optimized conditions, the prepared EM-PVP-K30 solid dispersions resembled potato-like, round, and irregular structures with a jagged surface. In contrast, the EM-PRIII solid dispersions were irregular solids with a microporous surface structure. The results of X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), ultraviolet (UV) spectrometry, and infrared (IR) spectrometry showed that the solid dispersions were formed by intermolecular hydrogen bonding. The solid dispersion preparation in PVP-K30 significantly improved the solubility and dissolution rate of EM, particularly the aqueous solubility, which reached a maximum of 37.5-times the EM technical solubility, when the feed ratio of 1:10 was employed to prepare the dispersion. Importantly, the wettable powder of EM-PVP-K30 solid dispersion enhanced the insecticidal activity of EM against the Plutella xylostella larvae. Furthermore, the solid dispersion preparation in PRIII afforded a significant advantage by prolonging the EM technical release in water at a pH below 7.0, especially when the PRIII content in solid dispersions was high. While the amplified toxicity of the wettable powder of EM-PRIII solid dispersions against the P. xylostella larvae showed no significant differences from that of the EM technical, the long-term toxicity under the field condition was much better than that of the commercially available EM 1.5% emulsifiable concentrate. Notably, solid dispersions with both the PVP-K30 and PRIII carriers reduced the effect of UV photolysis.

scholarly journals Hydrodynamics and Mass Transfer Analysis in BioFlow® Bioreactor Systems

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1311 ◽  
Author(s):  
Marian Kordas ◽  
Maciej Konopacki ◽  
Bartłomiej Grygorcewicz ◽  
Adrian Augustyniak ◽  
Daniel Musik ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Mixing Time ◽  
Mass Transfer Rate ◽  
Mass Transfer Process ◽  
Mixing Process ◽  
Stirred Tanks ◽  
Mixing Energy ◽  
Biotechnological Processes ◽  
Liquid Transfer ◽  
Mathematical Relationships

Biotechnological processes involving the presence of microorganisms are realized by using various types of stirred tanks or laboratory-scale dual-impeller commercial bioreactor. Hydrodynamics and mass transfer rate are crucial parameters describing the functionality and efficiency of bioreactors. Both parameters strictly depend on mixing applied during bioprocesses conducted in bioreactors. Establishing optimum hydrodynamics conditions for the realized process with microorganisms maximizes the yield of desired products. Therefore, our main objective was to analyze and define the main operational hydrodynamic parameters (including flow field, power consumption, mixing time, and mixing energy) and mass transfer process (in this case, gas–liquid transfer) of two different commercial bioreactors (BioFlo® 115 and BioFlo® 415). The obtained results are allowed using mathematical relationships to describe the analyzed processes that can be used to predict the mixing process and mass transfer ratio in BioFlo® bioreactors. The proposed correlations may be applied for the design of a scaled-up or scaled-down bioreactors.

Effect of Mixing Process on the Fracture Behavior of HA/PLLA Composite Material

2005 ◽  
Vol 297-300 ◽  
pp. 2453-2458 ◽  
Author(s):  
Sang Dae Park ◽  
Mitsugu Todo ◽  
Kazuo Arakawa ◽  
Yasuharu Takenoshita
Keyword(s):  
Fracture Toughness ◽  
Fracture Behavior ◽  
Mixing Time ◽  
Time Effect ◽  
Ductile Deformation ◽  
Fracture Surface Morphology ◽  
Mixing Process ◽  
Rotor Speed ◽  
Neat Plla ◽  
Scanning Electron

Effect of mixing process on the fracture behavior of HA/PLLA Composites were investigated. Fracture toughness values of HA/PLLA composites prepared under different mixing time and rotor speed were measured. The fracture surface morphology was also examined by scanning electron microscopy. It was found that the fracture toughness of HA/PLLA composite decreases due to decrease of ductile deformation of PLLA matrix and debonding of interfaces with increase of the rotor speed and mixing time. Effect of mixing process on neat PLLA was also assessed, and it was found that the fracture toughness of PLLA decreases due to such pocess. Disappearance of multiple craze formation and thermal degradation were found to be the primary mechanisms of the toughness degradation.

scholarly journals Digital Twinning Process for Stirred Tank Reactors/Separation Unit Operations through Tandem Experimental/Computational Fluid Dynamics (CFD) Simulations

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1511
Author(s):  
Blaž Oblak ◽  
Simon Babnik ◽  
Vivian Erklavec-Zajec ◽  
Blaž Likozar ◽  
Andrej Pohar
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mixing Time ◽  
Tracer Tests ◽  
Flow Distribution ◽  
Experimental Tests ◽  
Cfd Simulations ◽  
Experimental Conditions ◽  
Separation Unit ◽  
Time Required

Computational fluid dynamics simulations (CFD) were used to evaluate mixing in baffled and unbaffled vessels. The Reynolds-averaged Navier−Stokes k–ε model was implemented in OpenFOAM for obtaining the fluid flow field. The 95% homogenization times were determined by tracer tests. Experimental tests were conducted by injecting sodium chloride into the vessel and measuring the conductivity with two conductivity probes, while the simulations replicated the experimental conditions with the calculation of the transport of species. It was found that the geometry of the system had a great effect on the mixing time, since the irregular flow distribution, which can be obtained with baffles, can lead to local stagnation zones, which will increase the time needed to achieve the homogenization of the solute. It was also found that measuring local, pointwise concentrations can lead to a high underestimation of the global mixing time required for the homogenization of the entire vessel. Dissolution of sucrose was also studied experimentally and by mathematical modeling. The dissolution of sucrose was found to be kinetically limited and a very good agreement was found between the experiments and the modeling approach. The extent of the applicability of CFD simulations was evaluated for enabling rapid process design via simulations.

scholarly journals Influence of the addition sequence of PVA-fibers and water on mixing and rheological behavior of mortars

2016 ◽  
Vol 9 (2) ◽  
pp. 226-243 ◽  
Author(s):  
M. S. de França ◽  
F. A. Cardoso ◽  
R. G. Pileggi
Keyword(s):  
Rheological Behavior ◽  
Mechanical Performance ◽  
Mixing Time ◽  
Mix Design ◽  
Mixing Process ◽  
Water Addition ◽  
Test Parameters ◽  
The Matrix ◽  
Mixing Sequences ◽  
The Moment

ABSTRACT The mixing process of fiber-containing cementitious suspensions is a crucial factor to obtaining a good dispersion of fibers and guarantee adequate mechanical performance of the hardened products. The addition of fibers into the suspension causes reduction of the fluidity of the system due to factors inherent to the fibers, the matrix and their interaction. During mixing, these interactions make dispersion and homogenization processes more difficult due to the formation of fibers - particles agglomerates. Conventional techniques to assess workability of mortars are inadequate to evaluate the rheological behavior of fiber-reinforced systems, in which parameters like viscosity and yield stress are not completely taken into account. Therefore, this work employs rotational rheometry to evaluate the influence of fiber and water addition sequences on mixing and rheological behavior of mortars containing Polyvinyl Alcohol (PVA) fibers. Constant test parameters were: mixing time of 317s; impeller velocity 126.5 rpm; water flow 128g/s. A constant mix design was used with a water content of 16%wt, and a 0.2%vol of fibers were added to the reference composition. Four mixing sequences were studied: S1 and S2 are based on the addition of fibers at different stages of the mixing process; while in S3 and S4 not only the fibers are added at different stages, but also the water addition is performed in two steps (25% first and 75% latter).Results showed that it is possible to optimize the mixing step of fiber-containing systems by changing the moment of fiber addition into the mixture. The introduction of fibers after mixing the dry mortar with water, when it already had achieved its fluidity point, demanded a lower mixing effort and produced a more flowable material.

scholarly journals Experimental Study on the Lubrication and Cooling Effect of Graphene in Base Oil for Si3N4/Si3N4 Sliding Pairs

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 160
Author(s):  
Lixiu Zhang ◽  
Xiaoyi Wei ◽  
Junhai Wang ◽  
Yuhou Wu ◽  
Dong An ◽  
...  
Keyword(s):  
Rotational Speed ◽  
High Strength ◽  
Cooling Effect ◽  
Lubricating Oil ◽  
Protective Film ◽  
Test Results ◽  
Wear Properties ◽  
Experimental Conditions ◽  
Base Oil ◽  
Few Layer Graphene

Recently, the engineering structural ceramics as friction and wear components in manufacturing technology and devices have attracted much attention due to their high strength and corrosion resistance. In this study, the tribological properties of Si3N4/Si3N4 sliding pairs were investigated by adding few-layer graphene to base lubricating oil on the lubrication and cooling under different experimental conditions. Test results showed that lubrication and cooling performance was obviously improved with the addition of graphene at high rotational speeds and low loads. For oil containing 0.1 wt% graphene at a rotational speed of 3000 r·min−1 and 40 N loads, the average friction coefficient was reduced by 76.33%. The cooling effect on Si3N4/Si3N4 sliding pairs, however, was optimal at low rotational speeds and high loads. For oil containing 0.05 wt% graphene at a lower rotational speed of 500 r·min−1 and a higher load of 140 N, the temperature rise was reduced by 19.76%. In addition, the wear mark depth would decrease when adding appropriate graphene. The mechanism behind the reduction in friction and anti-wear properties was related to the formation of a lubricating protective film.

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