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

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.

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

2006 ◽  
Vol 314 ◽  
pp. 237-244 ◽  
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.

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

2015 ◽  
Vol 1105 ◽  
pp. 117-122 ◽  
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.

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

2019 ◽  
Vol 61 (12) ◽  
pp. 2503 ◽  
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.

scholarly journals Effect of Particle Size on the Hydraulic Characteristics of Mechanically and Biologically Treated Waste

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhenying Zhang ◽  
Xiufeng Pan ◽  
Jiahe Zhang ◽  
Hui Xu
Keyword(s):  
Particle Size ◽  
Large Scale ◽  
Void Ratio ◽  
Average Particle Size ◽  
Dry Mass ◽  
Dry Density ◽  
Average Particle ◽  
Vertical Permeability ◽  
The Difference ◽  
Reduce Emissions

Mechanical biological treatment (MBT) is a waste processing technology that helps conserve resources and reduce emissions harmful to the environment. The treatment of municipal solid waste (MSW) using MBT is a hot topic in environmental geotechnical engineering. Permeability tests were carried out on MBT waste using a compression and permeability combined apparatus and a large-scale vertical permeability apparatus taking the influence of particle size into consideration. The permeability of samples with smaller particle sizes was found to be lower for the same pressure and dry mass (%) of component. The best-fit line between the logarithmic permeability and variables such as the dry density was linear. As the dry density increased or the void ratio decreased, the permeability of samples with smaller particles decreased more. The logarithmic permeability increased with the increase in the average particle size and void ratio. The permeabilities of MBT waste corresponding to particle size ranges of 0–10, 0–20, and 0–40 mm were 10−10–10−5, 10−8–10−4, and 10−5–10−3 m/s, respectively. The difference between MBT waste and MSW was analyzed in terms of their permeability. The results of MBT waste were compared with those reported in previous studies to provide reference for the permeability analysis of MBT landfills.

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

2019 ◽  
Vol 50 (6) ◽  
pp. 1645-1664
Author(s):  
Khabat Khosravi ◽  
Amir H. N. Chegini ◽  
Andrew D. Binns ◽  
Prasad Daggupati ◽  
Luca Mao
Keyword(s):  
Hysteresis Loop ◽  
Average Particle Size ◽  
Equal Weight ◽  
Average Particle ◽  
Uniform Particles ◽  
Before And After ◽  
Load Transport ◽  
The Difference ◽  
Sediment Mixture ◽  
Bed Material

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.

A Novel Nanofluid Synthesis System for Preparation of Nanofluid

2007 ◽  
Vol 364-366 ◽  
pp. 431-436
Author(s):  
Ho Chang ◽  
Shih Chieh Lin
Keyword(s):  
Particle Size ◽  
Control System ◽  
Average Particle Size ◽  
Circulation System ◽  
Suspension Stability ◽  
Average Particle ◽  
Synthesis System ◽  
Average Value ◽  
The Difference ◽  
Tio2 Nanofluids

In this study, the author uses a novel nanofluid synthesis system to fabricate a TiO2 nanofluid. The improvement of the proposed nanofluid synthesis system focuses mainly on the pressure control system, coolant circulation system, parameter control system and the machine dimension of the original submerged arc nanofluid synthesis system. This helps to achieve an experimental machine with a fabrication condition to produce more stable and finer TiO2 nanofluids with a particle size of good reproducibility. Experiment is proceeded towards 15 sets of TiO2 nanofluid fabricated by the proposed system are tested under the experimental conditions of 250 V, 6 A of peak current, 2μs of discharge pause off time and 15 days of settling time. The experimental results show that the average Zeta potential of TiO2 nanofluids are -54.2 mv, and the difference between the data and the average value of each set is less than 7%. Furthermore, the average particle size is 45.3nm, and the difference between the data and the average value of each set is less than 6%. The fabricated TiO2 particles have an Anatase structure, and in the aspect of roundness measurement, the produced TiO2 has a good roundness of 0.3 nm. Experiment proves that the roundness of the fabricated TiO2 nanoparticles are much better than those fabricated by aerosol methods. Also, the fabricated nanofluid has a high suspension stability.

Enhanced catalytic activity of low-Pt content nanocatalysts supported on hollow carbon spheres for the ORR in alkaline media

MRS Advances ◽  
2020 ◽  
Vol 5 (57-58) ◽  
pp. 2961-2972
Author(s):  
P.C. Meléndez-González ◽  
E. Garza-Duran ◽  
J.C. Martínez-Loyola ◽  
P. Quintana-Owen ◽  
I.L. Alonso-Lemus ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Anion Exchange ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Alkaline Media ◽  
High Catalytic Activity ◽  
Average Particle ◽  
Carbon Spheres ◽  
Hollow Carbon ◽  
Hollow Carbon Spheres

In this work, low-Pt content nanocatalysts (≈ 5 wt. %) supported on Hollow Carbon Spheres (HCS) were synthesized by two routes: i) colloidal conventional polyol, and ii) surfactant-free Bromide Anion Exchange (BAE). The nanocatalysts were labelled as Pt/HCS-P and Pt/HCS-B for polyol and BAE, respectively. The physicochemical characterization of the nanocatalysts showed that by following both methods, a good control of chemical composition was achieved, obtaining in addition well dispersed nanoparticles of less than 3 nm TEM average particle size (d) on the HCS. Pt/HCS-B contained more Pt0 species than Pt/HCS-P, an effect of the synthesis method. In addition, the structure of the HCS remains more ordered after BAE synthesis, compared to polyol. Regarding the catalytic activity for the Oxygen Reduction Reaction (ORR) in 0.5 M KOH, Pt/HCS-P and Pt/HCS-B showed a similar performance in terms of current density (j) at 0.9 V vs. RHE than the benchmark commercial 20 wt. % Pt/C. However, Pt/HCS-P and Pt/HCS-B demonstrated a 6 and 5-fold increase in mass catalytic activity compared to Pt/C, respectively. A positive effect of the high specific surface area of the HCS and its interactions with metal nanoparticles and electrolyte, which promoted the mass transfer, increased the performance of Pt/HCS-P and Pt/HCS-B. The high catalytic activity showed by Pt/HCS-B and Pt/HCS-P for the ORR, even with a low-Pt content, make them promising cathode nanocatalysts for Anion Exchange Membrane Fuel Cells (AEMFC).

A New Method for Direct Determination of the Recoilless Fraction with Application to Magnetic Nanoparticles

2002 ◽  
Vol 721 ◽  
Author(s):  
Monica Sorescu
Keyword(s):  
Room Temperature ◽  
Average Particle Size ◽  
Direct Determination ◽  
Average Particle ◽  
Lattice Method ◽  
Recoilless Fraction ◽  
Single Room ◽  
Magnetite Particles ◽  
Physical Mixtures

AbstractWe propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19 nm.

Impact Assessment of Dynamic Characteristics on the Hydraulic Driven Machinery Operation

2018 ◽  
pp. 1-12
Author(s):  
A. D. Terenteva
Keyword(s):  
Dynamic Error ◽  
Total Error ◽  
Soil Layer ◽  
Hydraulic Drive ◽  
Hydraulic Cylinder ◽  
Working Mechanism ◽  
Automated Control ◽  
Vertical Coordinate ◽  
Construction Machinery ◽  
The Difference

In civil engineering in Russia, trenching for utilities is currently under digging. To perform such works, it is necessary to use high-precision construction machinery, because inaccurate performance of works can lead to the break down of existing utilities, thereby affecting the residents of nearby houses and demanding the additional works for renewal.The most universal labour saver to perform construction works is hydraulic driven single-bucket excavators, which provide up to 38% of works. Therefore, to improve technical characteristics that affect the accuracy of the work performed is an important task.High requirements for the performance of works are defined by existing construction regulations: an allowable soil layer to remain is at most 0.05 m. To fulfil such requirements, an exact assessment of the working mechanism position and a trench profile is necessary.Examination of a manually operated digging process shows that an operator provides operations untimely, however an automated control system can solve this problem. Dynamic phenomena in the working mechanism have the greatest impact on the accuracy of the works performed.To assess the bucket digging edge position accuracy, a mathematical model of the working mechanism has been created. Based on the cycle scheme of the working process, the excessive displacements of the hydraulic cylinder rods under the load are taken into account. By the end of the cycle, the difference between the specified and obtained positions along the vertical coordinate has been 0.0892 m.A dynamic error of the hydraulic drive system of the working mechanism is considered as a sum of the error due to excessive displacements of the hydraulic cylinder rods and the error due to delay of the hydraulic drive, with the latter being calculated for the average time of delay taking into account the data available in the literature. The total error of the bucket digging edge position of the working mechanism is 0.1176 m, which is 2 times more than the value of 0.05 mConformity of all the links with specification requirements does not guarantee compliance with the required displacement accuracy of the bucket digging edge, and, thus, the soil layer to remain in the base of the trench can exceed the regulated value of 0.05 m.

Determination of grinding parameters of fenugreek seed

1970 ◽  
Vol 26 (1) ◽  
pp. 16 ◽  
Author(s):  
S Balasubramanian ◽  
Rajkumar Rajkumar ◽  
K K Singh
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Moisture Content ◽  
Specific Energy ◽  
Feed Rate ◽  
Average Particle Size ◽  
Specific Energy Consumption ◽  
Average Particle ◽  
Fenugreek Seeds ◽  
Fenugreek Seed

Experiment to identify ambient grinding conditions and energy consumed was conducted for fenugreek. Fenugreek seeds at three moisture content (5.1%, 11.5% and 17.3%, d.b.) were ground using a micro pulverizer hammer mill with different grinding screen openings (0.5, 1.0 and 1.5 mm) and feed rate (8, 16 and 24 kg h-1) at 3000 rpm. Physical properties of fenugreek seeds were also determined. Specific energy consumptions were found to decrease from 204.67 to 23.09 kJ kg-1 for increasing levels of feed rate and grinder screen openings. On the other hand specific energy consumption increased with increasing moisture content. The highest specific energy consumption was recorded for 17.3% moisture content and 8 kg h-1 feed rate with 0.5 mm screen opening. Average particle size decreased from 1.06 to 0.39 mm with increase of moisture content and grinder screen opening. It has been observed that the average particle size was minimum at 0.5 mm screen opening and 8 kg h-1 feed rate at lower moisture content. Bond’s work index and Kick’s constant were found to increase from 8.97 to 950.92 kWh kg-1 and 0.932 to 78.851 kWh kg-1 with the increase of moisture content, feed rate and grinder screen opening, respectively. Size reduction ratio and grinding effectiveness of fenugreek seed were found to decrease from 4.11 to 1.61 and 0.0118 to 0.0018 with the increase of moisture content, feed rate and grinder screen opening, respectively. The loose and compact bulk densities varied from 219.2 to 719.4 kg m-3 and 137.3 to 736.2 kg m-3, respectively.  

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