Effect of Ultrasonic Frequency on Thickener Performance

Gravity thickening is an important aspect to solve numerous environmental and safety problems that were created by tailings discharging at low solid concentrations. Furthermore, in order to efficiently facilitate the separation of released water and solid sediments, a continuous thickening system with ultrasonic equipment has been used to investigate the thickening performance of copper-mine tailings under different ultrasonic frequencies (16 kHz, 20 kHz, 22 kHz, 25 kHz, and 28 kHz). After freeze-drying treatment, the underflow samples are imaged using the scanning electron microscope (SEM); then, the structure of floc or aggregates in the SEM images is quantifiably analyzed using the software of Image J. Results show that the underflow concentration increases as the ultrasonic frequency increases and decreases afterwards. A linear logarithmic function can explain the relationship between underflow concentration and run time at a certain ultrasonic. The underflow concentration is maximized at 64.47 wt. % when the ultrasonic frequency is 22 kHz. Based on the analysis on the microstructure of underflow samples, the minimum pore average size and pore average fraction are obtained when the ultrasonic frequency is 22 kHz, implying that 22 kHz is the optimum ultrasonic frequency combining the results of the underflow concentration.

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Room Temperature Syntheses of ZnO and Their Structures

Symmetry ◽

10.3390/sym13040733 ◽

2021 ◽

Vol 13 (4) ◽

pp. 733

Author(s):

Domenica Donia ◽

Elvira Maria Bauer ◽

Mauro Missori ◽

Ludovica Roselli ◽

Daniele Cecchetti ◽

...

Keyword(s):

Room Temperature ◽

Direct Synthesis ◽

Threshold Value ◽

Rietveld Analysis ◽

Synthesis Temperature ◽

Density Variation ◽

Controlled Synthesis ◽

Sem Images ◽

Aqueous Solvent ◽

Average Size

ZnO has many technological applications which largely depend on its properties, which can be tuned by controlled synthesis. Ideally, the most convenient ZnO synthesis is carried out at room temperature in an aqueous solvent. However, the correct temperature values are often loosely defined. In the current paper, we performed the synthesis of ZnO in an aqueous solvent by varying the reaction and drying temperatures by 10 °C steps, and we monitored the synthesis products primarily by XRD). We found out that a simple direct synthesis of ZnO, without additional surfactant, pumping, or freezing, required both a reaction (TP) and a drying (TD) temperature of 40 °C. Higher temperatures also afforded ZnO, but lowering any of the TP or TD below the threshold value resulted either in the achievement of Zn(OH)2 or a mixture of Zn(OH)2/ZnO. A more detailed Rietveld analysis of the ZnO samples revealed a density variation of about 4% (5.44 to 5.68 gcm−3) with the synthesis temperature, and an increase of the nanoparticles’ average size, which was also verified by SEM images. The average size of the ZnO synthesized at TP = TD = 40 °C was 42 nm, as estimated by XRD, and 53 ± 10 nm, as estimated by SEM. For higher synthesis temperatures, they vary between 76 nm and 71 nm (XRD estimate) or 65 ± 12 nm and 69 ± 11 nm (SEM estimate) for TP =50 °C, TD = 40 °C, or TP = TD = 60 °C, respectively. At TP = TD = 30 °C, micrometric structures aggregated in foils are obtained, which segregate nanoparticles of ZnO if TD is raised to 40 °C. The optical properties of ZnO obtained by UV-Vis reflectance spectroscopy indicate a red shift of the band gap by ~0.1 eV.

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Temperature-Driven Hydrocarbon Generation-Expulsion and Structural Transformation of Organic-Rich Shale Assessed by in situ Heating SEM

Frontiers in Earth Science ◽

10.3389/feart.2021.797760 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yuan Yuan ◽

Jijin Yang

Keyword(s):

Structural Changes ◽

Fracture Network ◽

Reservoir Rock ◽

Continuous Heating ◽

Hydrocarbon Generation ◽

Sem Images ◽

Cap Rock ◽

Hydrocarbon Expulsion ◽

The Relationship

Mud shale can serve as source or cap rock but also as a reservoir rock, and so the development of pores or cracks in shale has become of great interest in recent years. However, prior work using non-identical samples, varying fields of view and non-continuous heating processes has produced varying data. The unique hydrocarbon generation and expulsion characteristics of shale as a source rock and the relationship with the evolution of pores or cracks in the reservoir are thus not well understood. The present work attempted to monitor detailed structural changes during the continuous heating of shale and to establish possible relationships with hydrocarbon generation and expulsion by heating immature shale samples while performing in situ scanning electron microscopy (SEM) imaging and monitoring the chamber vacuum. Samples were heated at 20°C/min from ambient to 700°C with 30 min holds at 100°C intervals during which SEM images were acquired. The SEM chamber vacuum was found to change during sample heating as a consequence of hydrocarbon generation and expulsion. Two episodic hydrocarbon expulsion stages were observed, at 300 and 500°C. As the temperature was increased from ambient to 700°C, samples exhibited consecutive shrinkage, expansion and shrinkage, and the amount of structural change in the vertical bedding direction was greater than that in the bedding direction. At the same time, the opening, closing and subsequent reopening of microcracks was observed. Hydrocarbon generation and expulsion led to the expansion of existing fractures and the opening of new cracks to produce an effective fracture network allowing fluid migration. The combination of high-resolution SEM and a high-temperature heating stage allowed correlation between the evolution of pores or cracks and hydrocarbon generation and expulsion to be examined.

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Mechanical Properties of Chitosan-Starch Composite Filled Hydroxyapatite Micro- and Nanopowders

Journal of Nanomaterials ◽

10.1155/2011/391596 ◽

2011 ◽

Vol 2011 ◽

pp. 1-5 ◽

Cited By ~ 8

Author(s):

Jafar Ai ◽

Mostafa Rezaei-Tavirani ◽

Esmaeil Biazar ◽

Saeed Heidari K ◽

Rahim Jahandideh

Keyword(s):

Sol Gel ◽

Weight Ratio ◽

Tensile Modulus ◽

Mechanical Analysis ◽

Sem Images ◽

Chitosan Hydrogel ◽

Size Particle ◽

Average Size ◽

Hard Tissue Engineering ◽

Nano Size

Hydroxyapatite is a biocompatible ceramic and reinforcing material for bone implantations. In this study, Starch-chitosan hydrogel was produced using the oxidation of starch solution and subsequently cross-linked with chitosan via reductive alkylation method (weight ratio (starch/chitosan): 0.38). The hydroxyapatite micropowders and nanopowders synthesized by sol-gel method (10, 20, 30, 40 %W) were composited to hydrogels and were investigated by mechanical analysis. The results of SEM images and Zetasizer experiments for synthesized nanopowders showed an average size of 100 nm. The nanoparticles distributed as uniform in the chitosan-starch film. The tensile modulus increased for composites containing hydroxyapatite nano-(size particle: 100 nanometer) powders than composites containing micro-(size particle: 100 micrometer) powders. The swelling percentage decreased for samples containing hydroxyapatite nanopowder than the micropowders. These nanocomposites could be applied for hard-tissue engineering.

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The Morphology of Freeze-Dried Rubidium Chloride Powder

MRS Proceedings ◽

10.1557/proc-155-37 ◽

1989 ◽

Vol 155 ◽

Cited By ~ 3

Author(s):

J. K. G. Panitz ◽

J. A. Voigt ◽

F. A. Greulich ◽

M. J. Carr ◽

M. O. Eatough

Keyword(s):

Droplet Size ◽

Freeze Drying ◽

Low Concentrations ◽

Aerosol Spray ◽

Freeze Dried ◽

Primary Particles ◽

Ionic Compounds ◽

Freezing Cycle ◽

Average Size ◽

Stock Solutions

ABSTRACTWe have formed powders of a strongly ionic compound, RbCl by freezedrying. Stock solutions, varying from very low concentrations with 4 gm RbCl reagent dissolved in 100 cc water to saturated solutions with 80 gm reagent in 100 cc water, were sprayed into isopentane at -160°C. The droplet size in the spray was varied from relatively large 4-mm diameter droplets to extremely small droplets in an aerosol spray. It was determined that both the concentration of the stock solution and the droplet size affect the average size and the size distribution of the primary particles formed and the way in which these primary particles are bonded together. Unlike the powders of many less ionic compounds that are produced by freeze-drying, the primary particles in these RbCl powders are crystalline rather than amorphous. Analysis with an x-ray diffractometer with a cold stage indicates that crystallization occurs during the freezing cycle rather than during the sublimation period of the freeze-drying process.

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Relationships between snowfall density and solid hydrometeors, based on measured size and fall speed, for snowpack modeling applications

The Cryosphere ◽

10.5194/tc-10-2831-2016 ◽

2016 ◽

Vol 10 (6) ◽

pp. 2831-2845 ◽

Cited By ~ 7

Author(s):

Masaaki Ishizaka ◽

Hiroki Motoyoshi ◽

Satoru Yamaguchi ◽

Sento Nakai ◽

Toru Shiina ◽

...

Keyword(s):

Mass Flux ◽

Weather Forecasting ◽

Initial Density ◽

Quantitative Relationship ◽

Temperate Climate ◽

Snowfall Event ◽

Fall Speed ◽

Average Size ◽

Meteorological Elements ◽

The Relationship

Abstract. The initial density of deposited snow is mainly controlled by snowfall hydrometeors. The relationship between snowfall density and hydrometeors has been qualitatively examined by previous researchers; however, a quantitative relationship has not yet been established due to difficulty in parameterizing the hydrometeor characteristics of a snowfall event. Thus, in an earlier study, we developed a new variable, the centre of mass flux distribution (CMF), which we used to describe the main hydrometeors contributing to a snowfall event. The CMF is based on average size and fall speed weighted by the mass flux estimated from all measured hydrometeors in a snowfall event. It provides a quantitative representation of the predominant hydrometeor characteristics of the event. In this study, we examine the relationships between the density of newly fallen snow and predominant snow type as indicated by the CMFs. We measured snowfall density at Nagaoka, Japan, where riming and aggregation are predominant, simultaneously observing the size and fall speed of snowfall hydrometeors, and deduced the predominant hydrometeor characteristics of each snowfall event from their CMFs. Snow density measurements were carried out for short periods, 1 or 2 h, during which the densification of the deposited snow was negligible. Also, we grouped snowfall events based on similar hydrometeor characteristics. As a result, we were able to obtain not only the qualitative relationships between the main types of snow and snowfall density as reported by previous researchers, but also quantitative relationships between snowfall density and the CMF density introduced here. CMF density is defined as the ratio between mass and volume, assuming the diameter of a sphere is equal to the CMF size component. This quantitative relationship provides a means for more precise estimation of snowfall density based on snow type (hydrometeor characteristics), by using hydrometeor size and fall speed data to derive initial densities for numerical snowpack models, and the snow-to-liquid ratio for winter weather forecasting. In fact, we found that this method can more accurately estimate snowfall density compared with using meteorological elements, which is the method generally used in current snowpack models, even though some issues remain in parameterization for practical use. Transferability of the method developed in the temperate climate zone, where riming and aggregation are predominant, to other snowy areas is also an issue. However, the methodology presented in this study would be useful for other kinds of snow.

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Enhanced Magnetic Properties of Co-Doped BiFeO3 Thin Films via Structural Progression

Nanomaterials ◽

10.3390/nano10091798 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1798

Author(s):

Liang Bai ◽

Mingjie Sun ◽

Wenjing Ma ◽

Jinghai Yang ◽

Junkai Zhang ◽

...

Keyword(s):

Thin Films ◽

Magnetic Properties ◽

Sol Gel ◽

Sem Images ◽

Size Mismatch ◽

Structural Progression ◽

Gel Technique ◽

Average Size ◽

Perovskite Lattice ◽

Co Doped

Co3+ doping in BiFeO3 is expected to be an effective method for improving its magnetic properties. In this work, pristine BiFeO3 (BFO) and doped BiFe1-xCoxO3 (BFCxO, x = 0.01, 0.03, 0.05, 0.07 and 0.10) composite thin films were successfully synthesized by a sol–gel technique. XRD and Raman spectra indicate that the Co3+ ions are substituted for the Fe3+ ion sites in the BFO rhombohedral lattice. Raman vibration of oxygen octahedron is obviously weakened due to the lattice distortion induced by the size mismatch between two B-site cations (Fe3+ and Co3+ ions), which has an impact on the magnetic properties of BFCxO. SEM images reveal a denser agglomeration in Co-doped samples. TEM results indicate that the average size of grains is reduced due to the Co3+ substitution. XPS measurements illustrate that the replacement of Fe3+ with Co3+ effectively suppresses the generation of oxygen defects and increases the concentration of Fe3+ ions at the B-site of perovskite lattice. Vibrating sample magnetometer (VSM) measurements show that the remanent magnetization (Mr) of BFC0.07O (3.6 emu/cm3) and the saturation magnetization (Ms) of BFC0.10O (48.84 emu/cm3) thin film both increase by approximately two times at room temperature, compared with that of the pure BFO counterpart.

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The Relationship Between Internalization of Magnetic Nanoparticles and Changes of Cellular Optical Scatter Signal

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.18387 ◽

2008 ◽

Vol 8 (12) ◽

pp. 6310-6315

Author(s):

Jingguang Xia ◽

Song Zhang ◽

Yu Zhang ◽

Ming Ma ◽

Kang Xu ◽

...

Keyword(s):

Flow Cytometry ◽

Magnetic Nanoparticles ◽

Argon Laser ◽

Human Hepatoma Cells ◽

Cellular Iron ◽

High Viability ◽

A Cell ◽

Magnetic Labeling ◽

Average Size ◽

The Relationship

Carboxylmethyl starch sodium-coated magnetic nanoparticles (CMS@MNs) with average size of 10 nm were synthesized by chemical coprecipitation. Cellular iron content showed that CMS@MNs could be efficiently uptaken by human hepatoma cells. TEM image showed that clusters consisting of nanoparticles were enclosed within sub-micrometric endosomes and one cell contained several such endosomes. After incubation with the nanoparticles, a phenomenon appeared that the intensity of cellular side scatter signal (SSC) obtained by flow cytometry at 488 nm argon laser increased. It was demonstrated that the increase of SSC signal was induced by a cell itself, and mainly caused by the nanoparticles both adsorbed on the membrane and internalized into cytoplasm. Although without inducing cell death the treatments with the nanoparticles could lead to increased permeability of cell membrane to propidium iodide. Results implied a potential that flow cytometry might be used as a tool to rapidly evaluate and select cells with high magnetic labeling and high viability in cellular transplant.

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Active Edible Films Based on Arrowroot Starch with Microparticles of Blackberry Pulp Obtained by Freeze-Drying for Food Packaging

Polymers ◽

10.3390/polym11091382 ◽

2019 ◽

Vol 11 (9) ◽

pp. 1382 ◽

Cited By ~ 4

Author(s):

Gislaine Ferreira Nogueira ◽

Farayde Matta Fakhouri ◽

José Ignacio Velasco ◽

Rafael Augustus de Oliveira

Keyword(s):

Antioxidant Capacity ◽

Food Packaging ◽

Freeze Drying ◽

Water Solubility ◽

Research Work ◽

Edible Films ◽

Sem Images ◽

Film Forming ◽

Starch Films ◽

Arrowroot Starch

This research work evaluated the influence of the type of incorporation and variation in the concentration of blackberry pulp (BL) and microencapsulated blackberry pulp (ML) powders by freeze-drying on the chemical and physical properties of arrowroot starch films. Blackberry powders were added to the film-forming suspension in different concentrations, 0%, 20%, 30% and 40% (mass/mass of dry starch) and through two different techniques, directly (D) and by sprinkling (S). Scanning electron microscopy (SEM) images revealed that the incorporation of blackberry powder has rendered the surface of the film rough and irregular. Films incorporated with BL and ML powders showed an increase in thickness and water solubility and a decrease in tensile strength in comparison with the film containing 0% powder. The incorporation of blackberry BL and ML powders into films transferred colour, anthocyanins and antioxidant capacity to the resulting films. Films added with blackberry powder by sprinkling were more soluble in water and presented higher antioxidant capacity than films incorporated directly, suggesting great potential as a vehicle for releasing bioactive compounds into food.

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A Sacrificial Method for Fabricating Microchannel Accelerated by Galvanic Corrosion

Fluids Engineering ◽

10.1115/imece2005-81124 ◽

2005 ◽

Author(s):

Hongjun Zeng ◽

Alan Feinerman ◽

Zhiliang Wan

Keyword(s):

Cross Section ◽

Etch Rate ◽

Galvanic Corrosion ◽

Channel Width ◽

Etching Time ◽

Sem Images ◽

Sacrificial Material ◽

Relationship Of ◽

The Relationship

A metal sacrificial method has been investigated for creation of microchannels by galvanic corrosion in a metal multilayer. To achieve the fastest sacrificial metal combination, different metals and the corresponding etchants are chosen. Channels from 50 μm to 1 μm wide, 0.2 μm high, and 1500 μm long, as well as the channel array is fabricated, using Cr/Cu galvanic metal couple as sacrificial material. The relationship between the etching front vs. the etching time, and the relationship of the etch rate vs. channel width is measured and compared with the etching performance of the single metal. The measurement shows there is approximately 10 times faster etching in the galvanic coupled metals than that in the single metal. SEM images of the channels and channel array made by this method are presented. This method is compatible with the conventional VLSI process, and has the potential for fabricating microchannels with submicron or even nanometer cross section.

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Multidispersion Soot Interference Mechanism on SO2 Concentration Using NDIR

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.345.247 ◽

2013 ◽

Vol 345 ◽

pp. 247-250

Author(s):

Yan Jun Zhao ◽

Shou Guang Cheng ◽

Bin Qu

Keyword(s):

Light Intensity ◽

Measurement Accuracy ◽

Measurement Methods ◽

Infrared Light ◽

Characteristic Parameters ◽

Distribution Parameters ◽

Simulation Results ◽

Average Size ◽

The Relationship ◽

Interference Mechanism

NDIR is one of SO2 concentration measurement methods. SO2 concentration can be figured out through measuring the infrared light intensity changing. The light intensity can be attenuated by the particles, so the SO2 concentration is increased. To solve the particles interference, the multidispersion particles interference mechanism is established. Particles characteristic parameters which interferes the SO2 concentration include the dissipativity, concentration, average size and size distribution parameters. Simulation results give the relationship between the SO2 concentration and particles characteristic parameters. The method to reduce the interference of the SO2 concentration is brought out and the measurement accuracy can be improved.

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