scholarly journals Distributions of Particle Sizes in Black Soil and Their Environmental Significance in Northeast China

2021 ◽  
Vol 13 (7) ◽  
pp. 3706
Author(s):  
Binghe Yan ◽  
Yulan Zhang ◽  
Shuying Zang ◽  
Qiang Chen ◽  
Li Sun
Keyword(s):  
Particle Size ◽  
Wind Erosion ◽  
Black Soil ◽  
Vegetation Coverage ◽  
Normal Distribution Function ◽  
Particle Sizes ◽  
Environmental Implications ◽  
Long Distance ◽  
Black Soil Region ◽  
Log Normal

In recent years, black soil has decreased and degenerated heavily due to complicated functions of natural and artificial factors. Hence, characterizing distributions of particle sizes in black soil and their environmental influencing factors is important for understanding black soil degradation. A total of 116 surface soil samples in the top 20 cm from a typical black soil region in northeastern China were collected, and the spatial distribution of particle size parameters were characterized. Particle size-sensitive components were extracted quantitatively using the log-normal distribution function, and their environmental implications were investigated. The contents of black soil mechanical composition ranged from 7.8% to 79.3% for clay, 17.7% to 80.3% for silt, and 0% to 73.7% for sand, respectively. Median particle size ranged from 1.71 to 142.67 μm, with a coefficient of variation of 60%, indicating silt accounted for the majority of the composition. Four environmentally sensitive components were identified, including long-distance transported airborne deposits of clay dust (C1), successions from local parent materials (C2), short-distance deposits of silt particles (C3), and a component strongly disturbed by human activities (C4). C1 and C2 had relatively low variations, with C1 exhibiting the smallest variation, and C2 contributing highest proportion, showing no significant differences across all samples. C3 widely existed across samples, suggesting common wind erosion within the black soil region. C3 and C4 varied spatially, which was caused by the low vegetation coverage and high human disturbance of agricultural topsoil. The results suggest that windbreaks should be encouraged to reduce wind erosion in the black soil regions.

scholarly journals Stereological determination of dry-snow parameters for discrete-scatterer microwave modeling

1993 ◽  
Vol 17 ◽  
pp. 295-299 ◽  
Author(s):  
Jiancheng Shi ◽  
Robert E. Davis ◽  
Jeff Dozier
Keyword(s):  
Particle Size ◽  
Rayleigh Scattering ◽  
Size Variation ◽  
Normal Distribution Function ◽  
Scattering Coefficients ◽  
Brightness Temperatures ◽  
Back Scattering ◽  
Microstructure Parameters ◽  
Log Normal ◽  
Snow Microstructure

Modeling microwave back-scattering and emission from snow-packs requires the knowledge of snowpack characteristics and their dynamics to select an appropriate model. Both theory and field data show that microwave back-scattering coefficients and brightness temperatures are sensitive to parameters describing snow-microstructure. Stereological methods and other techniques can be applied to images of sections cut from undisturbed snow, and are used to obtain accurate and unbiased estimates of snow-microstructure parameters for discrete scatterer modeling. Assuming that the ice particle-size distribution can be characterized as a log-normal distribution function, we show that the parameters describing the distribution can be obtained from section images. The results show that, in addition to snow density and ice-particle size, the particle-size variation has great effect on dry-snow extinction properties. The optically equivalent ice-particle size for Rayleigh scattering in a snowpack with grain-size variations can be determined from the stereological measurements from snow sections.

scholarly journals Stereological determination of dry-snow parameters for discrete-scatterer microwave modeling

1993 ◽  
Vol 17 ◽  
pp. 295-299 ◽  
Author(s):  
Jiancheng Shi ◽  
Robert E. Davis ◽  
Jeff Dozier
Keyword(s):  
Particle Size ◽  
Rayleigh Scattering ◽  
Size Variation ◽  
Normal Distribution Function ◽  
Scattering Coefficients ◽  
Brightness Temperatures ◽  
Back Scattering ◽  
Microstructure Parameters ◽  
Log Normal ◽  
Snow Microstructure

Modeling microwave back-scattering and emission from snow-packs requires the knowledge of snowpack characteristics and their dynamics to select an appropriate model. Both theory and field data show that microwave back-scattering coefficients and brightness temperatures are sensitive to parameters describing snow-microstructure. Stereological methods and other techniques can be applied to images of sections cut from undisturbed snow, and are used to obtain accurate and unbiased estimates of snow-microstructure parameters for discrete scatterer modeling. Assuming that the ice particle-size distribution can be characterized as a log-normal distribution function, we show that the parameters describing the distribution can be obtained from section images. The results show that, in addition to snow density and ice-particle size, the particle-size variation has great effect on dry-snow extinction properties. The optically equivalent ice-particle size for Rayleigh scattering in a snowpack with grain-size variations can be determined from the stereological measurements from snow sections.

Efficiencies of sediment samplers for wind erosion measurement

Soil Research ◽  
1993 ◽  
Vol 31 (4) ◽  
pp. 519 ◽  
Author(s):  
Y Shao ◽  
GH Mctainsh ◽  
JF Leys ◽  
MR Raupach
Keyword(s):  
Particle Size ◽  
Wind Erosion ◽  
Collection Efficiency ◽  
Single Point ◽  
Sediment Supply ◽  
Wind Tunnels ◽  
Particle Sizes ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Clay Particles

We investigate the efficiency of three sediment samplers used for studies of wind erosion: a vertically integrating trap (an active, modified Bagnold trap for measuring vertically integrated streamwise sediment fluxes, designed for use in a portable wind tunnel); and two single-point, passive traps, the Leach trap (a small sampler of simple design, mainly for use in wind tunnels) and the Fryrear trap (a rugged sampler for field use). The vertically integrating trap is calibrated using a 'weighed sediment supply' technique in which a weighed sediment source is blown away completely during a calibration run. The single-point traps are calibrated against an accurate isokinetic sampler. The collection efficiency of all three traps is determined both in bulk and as a function of particle size. The results for overall efficiency E (for aeolian sand-sized particles) are: for the vertically integrating trap, E = 1.02 �.05; for the Leach trap, E = 0.85 � 0.05 with a slight tendency to increase with wind speed; and for the Fryrear trap, E = 0.90 � 0.05 (with or without a rain hood). Particle size analyses, carried out on the sediments collected by the traps under test and also the isokinetic sampler (assumed to have E = 1 for all particle sizes), show that the particle size distributions of the trapped sediments do not differ significantly from those of the isokinetic sampler. This uexpected result is a feature of the soils used for the tests, for which clay particles are mainly transported as small aggregates or clay skins upon sand grains.

Centrifuge Study on Influence of Particle Size, Compression and Substratum on Particle-Surface Adhesion Force

2008 ◽  
Vol 591-593 ◽  
pp. 347-351 ◽  
Author(s):  
M.A. Felicetti ◽  
José Renato Coury ◽  
M.L. Aguiar
Keyword(s):  
Particle Size ◽  
Phosphate Rock ◽  
Adhesion Force ◽  
Rotation Speed ◽  
Particle Surface ◽  
Particle Sizes ◽  
Adhesion Forces ◽  
Surface Adhesion ◽  
Log Normal ◽  
Log Normal Distribution

The centrifugal technique was used to investigate the influence of particle size, applied compression and substrate materials (stainless steel, glass, Teflon® and PVC) on particle-surface adhesion force. Phosphate rock and manioc starch particles were used in a microcentrifuge that contained specially designed centrifuge tubes and reached a maximum rotation speed of 14,000 rpm. The profile of adhesion force followed a log-normal distribution and adhesion force increased linearly with particle size and the increment of the compression force. The manioc starch particles presented adhesion forces greater than those for the phosphate rock particles for all particle sizes studied. The glass substrate showed a higher adherence than other materials, most probably due to its hardness and polishing.

Surface energy of cellulosic materials: The effect of particle morphology, particle size, and hydroxyl number

TAPPI Journal ◽  
2015 ◽  
Vol 14 (9) ◽  
pp. 565-576 ◽  
Author(s):  
YUCHENG PENG ◽  
DOUGLAS J. GARDNER
Keyword(s):  
Particle Size ◽  
Surface Energy ◽  
Particle Morphology ◽  
Nanofibrillated Cellulose ◽  
Particle Sizes ◽  
Hydroxyl Number ◽  
Small Individual ◽  
Dispersion Component ◽  
Commercial Applications ◽  
Lower Temperature

Understanding the surface properties of cellulose materials is important for proper commercial applications. The effect of particle size, particle morphology, and hydroxyl number on the surface energy of three microcrystalline cellulose (MCC) preparations and one nanofibrillated cellulose (NFC) preparation were investigated using inverse gas chromatography at column temperatures ranging from 30ºC to 60ºC. The mean particle sizes for the three MCC samples and the NFC sample were 120.1, 62.3, 13.9, and 9.3 μm. The corresponding dispersion components of surface energy at 30°C were 55.7 ± 0.1, 59.7 ± 1.3, 71.7 ± 1.0, and 57.4 ± 0.3 mJ/m2. MCC samples are agglomerates of small individual cellulose particles. The different particle sizes and morphologies of the three MCC samples resulted in various hydroxyl numbers, which in turn affected their dispersion component of surface energy. Cellulose samples exhibiting a higher hydroxyl number have a higher dispersion component of surface energy. The dispersion component of surface energy of all the cellulose samples decreased linearly with increasing temperature. MCC samples with larger agglomerates had a lower temperature coefficient of dispersion component of surface energy.

Characteristic of the zimoseptoria tritici population by virulence in the of the Central Black Soil region of Russia

2020 ◽  
Author(s):  
J.V. Zeleneva J.V. ◽  
◽  
V.P. Sudnikova V.P.
Keyword(s):  
Black Soil ◽  
Black Soil Region ◽  
Intraspecific Structure ◽  
Wheat Lines ◽  
Significant Polymorphism

Based on the analysis of the intraspecific structure of the fungus Zimoseptoria. tritici, it was found that this species has significant polymorphism. Using monogenic wheat lines (Oasis (Stb1), Veranopolis (Stb2), Israel (Stb3), Tadinia (Stb4), CS / Synthetic (Stb5), Estanzuela Federal (Stb7)), the population of Z. tritici in the Central Black Earth region was tested. High heterogeneity of monosporous isolates of Z. tritici by virulence was revealed.

scholarly journals Effect of particle size on phytochemical composition and antioxidant properties of Sargassum cristaefolium ethanol extract

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. S. Prasedya ◽  
A. Frediansyah ◽  
N. W. R. Martyasari ◽  
B. K. Ilhami ◽  
A. S. Abidin ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Particle Size ◽  
Antioxidant Activities ◽  
Antioxidant Properties ◽  
Ethanol Extract ◽  
Total Phenolic ◽  
Particle Sizes ◽  
Epicatechin Gallate ◽  
Particle Size Reduction ◽  
Phytochemical Composition

AbstractSample particle size is an important parameter in the solid–liquid extraction system of natural products for obtaining their bioactive compounds. This study evaluates the effect of sample particle size on the phytochemical composition and antioxidant activity of brown macroalgae Sargassum cristaefolium. The crude ethanol extract was extracted from dried powders of S.cristeafolium with various particle sizes (> 4000 µm, > 250 µm, > 125 µm, > 45 µm, and < 45 µm). The ethanolic extracts of S.cristaefolium were analysed for Total Phenolic Content (TPC), Total Flavonoid Content (TFC), phenolic compound concentration and antioxidant activities. The extract yield and phytochemical composition were more abundant in smaller particle sizes. Furthermore, the TPC (14.19 ± 2.08 mg GAE/g extract to 43.27 ± 2.56 mg GAE/g extract) and TFC (9.6 ± 1.8 mg QE/g extract to 70.27 ± 3.59 mg QE/g extract) values also significantly increased as particle sizes decreased. In addition, phenolic compounds epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and Epigallocatechin gallate (EGCG) concentration were frequently increased in samples of smaller particle sizes based on two-way ANOVA and Tukey’s multiple comparison analysis. These results correlate with the significantly stronger antioxidant activity in samples with smaller particle sizes. The smallest particle size (< 45 µm) demonstrated the strongest antioxidant activity based on DPPH, ABTS, hydroxyl assay and FRAP. In addition, ramp function graph evaluates the desired particle size for maximum phytochemical composition and antioxidant activity is 44 µm. In conclusion, current results show the importance of particle size reduction of macroalgae samples to increase the effectivity of its biological activity.

scholarly journals Experimental Analysis of the Mechanical Properties and Resistivity of Tectonic Coal Samples with Different Particle Sizes

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2303
Author(s):  
Congyu Zhong ◽  
Liwen Cao ◽  
Jishi Geng ◽  
Zhihao Jiang ◽  
Shuai Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Coalbed Methane ◽  
Coal Sample ◽  
Fine Particles ◽  
Particle Sizes ◽  
Tectonic Coal

Because of its weak cementation and abundant pores and cracks, it is difficult to obtain suitable samples of tectonic coal to test its mechanical properties. Therefore, the research and development of coalbed methane drilling and mining technology are restricted. In this study, tectonic coal samples are remodeled with different particle sizes to test the mechanical parameters and loading resistivity. The research results show that the particle size and gradation of tectonic coal significantly impact its uniaxial compressive strength and elastic modulus and affect changes in resistivity. As the converted particle size increases, the uniaxial compressive strength and elastic modulus decrease first and then tend to remain unchanged. The strength of the single-particle gradation coal sample decreases from 0.867 to 0.433 MPa and the elastic modulus decreases from 59.28 to 41.63 MPa with increasing particle size. The change in resistivity of the coal sample increases with increasing particle size, and the degree of resistivity variation decreases during the coal sample failure stage. In composite-particle gradation, the proportion of fine particles in the tectonic coal sample increases from 33% to 80%. Its strength and elastic modulus increase from 0.996 to 1.31 MPa and 83.96 to 125.4 MPa, respectively, and the resistivity change degree decreases. The proportion of medium particles or coarse particles increases, and the sample strength, elastic modulus, and resistivity changes all decrease.

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