Difference in the bed load transport of graded and uniform sediments during floods: An experimental investigation

Abstract The objective of this study was to experimentally evaluate the difference in the transport of uniform (5.17, 10.35, 14, 20.7 mm) and graded sediment (mixture of these rounded particles with equal weight proportions) under different unsteady flow hydrographs in a 12 m long, 0.5 m wide and deep glass-walled flume. There was a lag time between fractions and uniform particles, such that peaks of coarser and finer fraction particles occurred before and after the peak of uniform sediment with the same size, respectively. Comparison between uniform particles and fractions in graded sediment showed that the sediment transport rate of fine and coarse fractions was lower and higher than their counterpart uniform particles, respectively. Overall, the uniform particles demonstrated a clockwise hysteresis loop and graded sediment had a counterclockwise hysteresis loop. The mobility of coarser fractions increased during the rising limb of hydrograph, whereas the mobility of finer fractions increased during the falling limb. In general, the mobility of coarse fractions increased and that of fine fractions reduced. Result of transported sediment showed that average particle size collected in traps (Db50) was coarser than bed material (Ds50) on both limbs. The relative transport ratio for uniform and graded sediment is higher and lower than 1, respectively.

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Water Versus Acetone Electrophoretic Deposition of Hydroxyapatite on 316L Stainless Steel

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.314.237 ◽

2006 ◽

Vol 314 ◽

pp. 237-244 ◽

Cited By ~ 4

Author(s):

Georgina García-Ruiz ◽

Gregorio Vargas ◽

J. Méndez-Nonell ◽

A. Uribe S.

Keyword(s):

Stainless Steel ◽

Deposition Time ◽

316L Stainless Steel ◽

Average Particle Size ◽

High Resistivity ◽

Average Particle ◽

Water Suspensions ◽

Before And After ◽

The Difference ◽

Deposit Weight

Hydroxyapatite (HAP) was electrophoretically deposited on 316L stainless steel in order to promote a bioactive surface. The effect of dispersing media (water and acetone), applied voltage and the deposition time on the deposit weight and microstructure of the coatings was evaluated. The deposition time was varied in the range of 1 to 900 s for water suspensions and 0.5 to 180 s for acetone suspensions. Suspensions were prepared by using HAP powder with an average particle size of 1.5 μm at a concentration of 1 % by weight. The deposition was performed under a direct current (DC) field of 400 to 1000 V for acetone suspensions and 5 to 50 V for water suspensions. The coatings were analyzed using scanning electron microscopy. The amount of hydroxyapatite on the surface of the metallic substrate was evaluated by determining the difference in weight of the samples, before and after the electrophoretic process. The stabilization of HAP particles in water was achieved using 1 % by weight of Dispex N40TM and 0.001M KCl. Under this condition the zeta potential of HAP in water suspension was –28 mV. Non additive was required in acetone suspensions. Dense, homogeneous and crack-free coatings of sub-micron particles (0.63 mg/cm2) were obtained by applying 5 V during 60 s in water suspensions. Above a DC field of 5 V the hydrolysis of water seriously difficulties the coatings formation. Homogeneous and crack-free coatings of sub-micron particles (1.45 mg/cm2) were also obtained in acetone suspensions applying 400 to 1000 V during 5 s. Lower voltages were not used with acetone suspensions due to its high resistivity.

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Obtaining the conductive SnO2 films by chemical bath deposition method

Butlerov Communications ◽

10.37952/roi-jbc-01/19-60-11-1 ◽

2019 ◽

Vol 60 (11) ◽

pp. 1-10

Author(s):

Vladislav I. Rogozin ◽

◽

Vyacheslav F. Markov ◽

Larisa N. Maskaeva ◽

Anastasia E. Krasovskaya ◽

...

Keyword(s):

Tin Dioxide ◽

Solid Phase ◽

Average Particle Size ◽

Ammonium Fluoride ◽

Contact Layer ◽

Average Particle ◽

Solution Ph ◽

Before And After ◽

Initial Salt ◽

Conductive Properties

Thanks to such unique properties as transparency and conductivity tin dioxide often utilize as transparent contact layer to produce displays, solar cells, and sensor devices. Hydrochemical method of deposition SnO2 films is a perspective due to its simplicity, and economical efficiency. The ionic equilibria analysis was carried out and the boundary conditions of Sn(OH)2 solid phase formation in the «Sn2+ – H2O – OH‾» system calculated. It was established, that tin(II) hydroxide may be obtain in the range 2 < pH < 12. Preliminary results allow to determinate an optimal mixture sourness interval 1 < pH < 5. Revealed, that the thickness of the Sn(OH)2 films strongly depends on the solution pH. Maximum value of 488 nm reached at pH = 8. Conductive SnO2 layers were obtained on a glass and sitall substrates with simultaneously presence of antimony chloride and ammonium fluoride followed by annealing in air. The thickness vs temperature and thickness vs tin initial salt concentration dependences were installed. The uniform tin hydroxide layers with a thickness of ~74 nm may be synthesized under pH = 2 conditions. By the electron microscopy method the average particle size was established changing from 200 to 400 nm for as-synthesized films, to ~20 nm for annealed which indicates the nanostructure nature of the films. The morphology, elemental composition and conductive properties of deposited films were investigated before and after heating stage. Studying the annealing temperature influence at the film resistance were identified a three temperature ranges within which the films sharply differ in their conductive properties, which is associated with phase and structural transformations in them. Shown, that the most conductive SnO2 films with the omic resistance 3-5 kOm/sm were obtained at the temperature range 620-870 K.

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Impacts of Acid Treatment on the Characteristics of Native Corn Starch Granules

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.221.72 ◽

2011 ◽

Vol 221 ◽

pp. 72-77 ◽

Cited By ~ 1

Author(s):

Xin Jin ◽

Shuan Qing Hou ◽

Xiao Xu Sha ◽

Liang Yu

Keyword(s):

Aqueous Solution ◽

Particle Size ◽

Acid Treatment ◽

Corn Starch ◽

Average Particle Size ◽

Peak Temperature ◽

Average Particle ◽

Starch Granules ◽

Acid Modification ◽

Before And After

Native corn starches were acid-treated at 53 °C for hours in HCl aqueous solution. The peak temperature (Tp) and heat of gelatinization (ΔHgel) before and after treatments were determined. The average particle size, TG and viscosity were measured. The results showed that the viscosity of corn starch decreased from 630mPa to 4.6mPa after acid treatment for 6h. The average particle size decreased and ΔHgel decreased obviously after acid modification.

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Analysis of The Migration and Accumulation Process of Nitrate-nitrogen Pollutants in The Unsaturated Zone of Soil

E3S Web of Conferences ◽

10.1051/e3sconf/202129301004 ◽

2021 ◽

Vol 293 ◽

pp. 01004

Author(s):

Xiangcai Li ◽

Ping Jing

Keyword(s):

Unsaturated Zone ◽

Maximum Concentration ◽

North China ◽

Nitrate Nitrogen ◽

Average Particle Size ◽

Soil Layer ◽

Average Particle ◽

Migration Process ◽

The Difference ◽

Nitrogen Pollutants

In order to understand the migration process of nitrate-nitrogen pollutants in the shallow unsaturated zone of the soil, the Tianjin coastal dredger and typical fluvo-aquic soils in North China were used as the research objects. The Hydrus-1D software was used to establish a numerical model to simulate nitrate. The pollution process of nitrogen pollutants in the unsaturated zone of soil, the results show that: during the migration process of the two kinds of shallow vadose zones of soil, the nitrate-nitrogen pollutants migrate downward at the maximum concentration before reaching the maximum concentration. After the maximum concentration, the concentration of nitrate nitrogen in the soil no longer increases; due to the difference in the average particle size of the soil, the migration rate of nitrate nitrogen in fluvo-aquic soil is significantly greater than that in artificial dredger soil. Nitrate nitrogen is in the simulation period completely passing through the simulated soil layer, the fluvo-aquic soil is completely passed through by nitrate nitrogen at 2d, and the artificial dredge fill is completely passed through by nitrate nitrogen at 2.5d.

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Improving the CO and CH4 Gas Sensor Response at Room Temperature of α-Fe2O3(0001) Epitaxial Thin Films Grown on SrTiO3(111) Incorporating Au(111) Islands

Coatings ◽

10.3390/coatings11070848 ◽

2021 ◽

Vol 11 (7) ◽

pp. 848

Author(s):

Aída Serrano ◽

Jesús López-Sánchez ◽

Iciar Arnay ◽

Rosalía Cid ◽

María Vila ◽

...

Keyword(s):

Particle Size ◽

Room Temperature ◽

Gas Sensing ◽

Structural Characteristics ◽

Average Particle Size ◽

Average Particle ◽

Epitaxial Thin Films ◽

Before And After ◽

Crystallographic Axes ◽

Gas Exposure

In this work, the functional character of complex α-Fe2O3(0001)/SrTiO3(111) and Au(111) islands/α-Fe2O3(0001)/SrTiO3(111) heterostructures has been proven as gas sensors at room temperature. Epitaxial Au islands and α-Fe2O3 thin film are grown by pulsed laser deposition on SrTiO3(111) substrates. Intrinsic parameters such as the composition, particle size and epitaxial character are investigated for their influence on the gas sensing response. Both Au and α-Fe2O3 layer show an island-type growth with an average particle size of 40 and 62 nm, respectively. The epitaxial and incommensurate growth is evidenced, confirming a rotation of 30° between the in-plane crystallographic axes of α-Fe2O3(0001) structure and those of SrTiO3(111) substrate and between the in-plane crystallographic axes of Au(111) and those of α-Fe2O3(0001) structure. α-Fe2O3 is the only phase of iron oxide identified before and after its functionalization with Au nanoparticles. In addition, its structural characteristics are also preserved after Au deposition, with minor changes at short-range order. Conductance measurements of Au(111)/α-Fe2O3(0001)/SrTiO3(111) system show that the incorporation of epitaxial Au islands on top of the α-Fe2O3(0001) layer induces an enhancement of the gas-sensing activity of around 25% under CO and 35% under CH4 gas exposure, in comparison to a bare α-Fe2O3(0001) layer grown on SrTiO3(111) substrates. In addition, the response of the heterostructures to CO gas exposure is around 5–10% higher than to CH4 gas in each case.

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Preparation and Magnetic Properties of α-MnO2 Nanoparticles

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.492.264 ◽

2011 ◽

Vol 492 ◽

pp. 264-267 ◽

Cited By ~ 2

Author(s):

Bao Ling Zhu ◽

Qiherima ◽

Li Lv ◽

Xiao Jing Wang

Keyword(s):

Hysteresis Loop ◽

Magnetic Hysteresis ◽

Average Particle Size ◽

Magnetic Hysteresis Loop ◽

Molar Ratio ◽

Thermal Method ◽

Average Particle ◽

Straight Line ◽

Lower Temperature ◽

Average Size

α-MnO2 nanoparticles with the average size about 22-29 nm were synthesized by hydro- thermal method. The as-synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform-Infrared Rediation (FT-IR) and thermogravimetric-differential thermal analysis (TG- DTA). We find that the average particle size of α-MnO2 is increased with the reaction temperature increasing. The diluent reactant is beneficial for the growth of α-MnO2. The smaller the molar ratio of K/Mn is, the more stable α-MnO2 phase is. The Neel temperature (TN) of nano-α-MnO2 is 5.0K obtained by the magnetic susceptibility determination, lower then the value of 24.5K for MnO2 single crystal phase. The magnetic hysteresis loop can be observed obviously at T = 5.0 K. It indicated that when the particles are at the level of nano-size level, the anti-ferromagnetic MnO2 showed the ferromagnetic nature at the lower temperature. When the temperature is high up to 60.0K, the magnetic hysteresis loop can't be observed. While when the temperature is at 120.0K, a straight line of magnetic hysteresis loop is obtained, indicating the paramagnetic magnetic nature of our sample.

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Solar Reflective Pigment of TiO2 Nanoparticle Coated on Mica and Thermal Property of its Isolation-Heat Paint

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1105.117 ◽

2015 ◽

Vol 1105 ◽

pp. 117-122 ◽

Cited By ~ 1

Author(s):

Hyun Jin Lee ◽

Dae Sung Kim ◽

Seung Ho Lee ◽

Byung Ki Choi ◽

Kwang Choong Kang

Keyword(s):

Thermal Property ◽

Average Particle Size ◽

Measuring System ◽

Thickness Variation ◽

Average Particle ◽

Solar Reflectance ◽

Color Coordinate ◽

The Difference ◽

Relationship Of ◽

The Relationship

TiO2coated mica (TiO2/Mica) as solar reflective pigment was prepared under hydrothermal treatment. Dispersed TiO2nanosol, having an average particle size of about 25-30nm, was coated on mica flake by the difference between the surface charge of the particles at pH 2 and then calcined at 850°C to stabilize the coated layer on mica. The CIE color coordinate and total solar reflectance (TSR) properties of these pigments were investigated in relation to thickness variation of TiO2layer coated on mica having various lateral sizes. Dense and uniform TiO2layers were tightly coated on the surfaces on mica substrates. Isolation-heat paints were prepared with 20wt% pigments fully dispersed in acryl-urethane resin and several additives to coat the film uniformly. Thermal property of these films, recorded by an isolation-heat measuring system, was observed for the relationship of TSR value according to the thickness of TiO2layer and mica’s lateral size, compared to TiO2itself.

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Improving the CO and CH4 Gas Sensor Response at Room Temperature of α-Fe2O3(0001) Epitaxial Thin Films Grown on SrTiO3(111) Incorporating Au(111) Islands

10.20944/preprints202106.0539.v1 ◽

2021 ◽

Author(s):

Aída Serrano ◽

Jesus López-Sánchez ◽

Iciar Arnay ◽

Rosalía Cid ◽

Maria Vila ◽

...

Keyword(s):

Gas Sensor ◽

Room Temperature ◽

Au Nanoparticles ◽

Gas Sensing ◽

Average Particle Size ◽

Average Particle ◽

Epitaxial Thin Films ◽

Island Type ◽

Before And After ◽

Crystallographic Axes

In this work epitaxial Au islands have been grown on epitaxial α-Fe2O3 thin film by pulsed laser deposition on SrTiO3(111) substrate. Both Au and α-Fe2O3 layer show an island-type growth with an average particle size of 40 and 62 nm, respectively. The crystallographic coupling of lattices is confirmed with a rotation of 30º between the in-plane crystallographic axes of α-Fe2O3(0001) structure and those of SrTiO3(111) substrate and between the in-plane crystallographic axes of Au(111) and those of α-Fe2O3(0001) structure. α-Fe2O3 is the only phase of iron oxide identified before and after its functionalization with Au nanoparticles. In addition, its structural character-istics are also preserved after Au deposition, with minor changes at short-range order. The func-tional character of the complex systems as gas sensor has been proven at room temperature. Con-ductance measurements of Au(111)/α-Fe2O3(0001)/ SrTiO3(111) system show that the incorpora-tion of Au islands on top of the α-Fe2O3(0001) layer induces an enhancement of the gas-sensing ac-tivity for CO and CH4 gas in comparison to a bare α-Fe2O3(0001) layer grown on SrTiO3(111).

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Магнитные свойства нанокристаллов Bi-=SUB=-1-x-=/SUB=-Ca-=SUB=-x-=/SUB=-FeO-=SUB=-3-delta-=/SUB=-

Физика твердого тела ◽

10.21883/ftt.2019.12.48585.549 ◽

2019 ◽

Vol 61 (12) ◽

pp. 2503 ◽

Cited By ~ 1

Author(s):

Н.А. Ломанова ◽

М.В. Томкович ◽

А.В. Осипов ◽

В.В. Панчук ◽

В.Г. Семенов ◽

...

Keyword(s):

Average Particle Size ◽

Fine Fraction ◽

Average Crystallite Size ◽

Combustion Method ◽

Average Particle ◽

X Ray ◽

Energy Dispersive Microanalysis ◽

The Difference ◽

Glycine Nitrate Combustion ◽

Bismuth Orthoferrite

Nanocrystalline magnetically ordered materials based on Ca-doped bismuth orthoferrite were synthesized by glycine-nitrate combustion method. The samples were characterized by X-ray diffractometry, helium pycnometry, Brunauer–Emmett–Teller method, scanning electron microscopy and elemental energy dispersive microanalysis. It was shown that all samples were isostructural to bismuth orthoferrite. The particles of nanopowders (with average particle size of about 0.3 m) were composed of nanocrystals (with average crystallite size of about 40 nm). The difference between magnetic properties of Ca-doped samples and pure bismuth orthoferrite were demonstrated by Mössbauer spectroscopy and magnetometry. It was found that the samples contain nanocrystals with modified magnetic parameters and a small amount of fine fraction of other phases with a magnetic order.

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A Study on Synthesis and Characterization of Dy-Doped La0.6Sr0.4Co0.2Fe0.8O3−δ via the Coprecipitation Method

Journal of Chemistry ◽

10.1155/2021/5577465 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Negin Mohammadi ◽

Zahra Khakpour ◽

Amir Maghsoudipour ◽

Aida Faeghinia

Keyword(s):

Phase Formation ◽

Perovskite Phase ◽

Average Particle Size ◽

Xrd Analysis ◽

Coprecipitation Method ◽

Synthesis Process ◽

Average Particle ◽

Powder Morphology ◽

Before And After

The perovskite Lanthanum Strontium Cobalt Ferrite (LSCF) is investigated as the cathode material used in intermediate-temperature solid oxide fuel cells (IT-SOFCs). In the present study, La0.6−xDyxSr0.4Co0.2Fe0.8O3−δ (x = 0, 0.3, 0.6) was synthesized through the coprecipitation method. The obtained precipitate was calcined at 500, 700, 900, and 1000°С. Phase characterization of the synthesized LSCF and LDySCF powder before and after heat treatment at 700°С was carried out by X-ray diffraction (XRD) analysis. XRD patterns revealed that the perovskite phase was obtained at 700°С in all calcined samples. Chemical bond study to investigate the synthesis process was conducted using the Fourier transform infrared spectroscopy technique. Thermal analysis of DTA and TG has been utilized to investigate how the calcination temperature affects the perovskite phase formation. According to the STA results, the perovskite phase formation started at 551°С and completed at 700°С. The density values of synthesized powders were 6.10, 6.11, and 6.37 g·cm−3for the undoped and doped samples calcined at 700°С. Powder morphology was studied by field emission scanning electron microscopy (FE-SEM). The micrographs showed the spherical-shaped particles with the average particle size of 24–131 nm.

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