scholarly journals Permeability and Microstructure of a Saline Intact Loess after Dry-Wet Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Jian Xu ◽  
Chang Ren ◽  
Songhe Wang ◽  
Jingyu Gao ◽  
Xiangang Zhou
Keyword(s):  
Sodium Sulfate ◽  
Permeability Coefficient ◽  
Empirical Relationship ◽  
Salt Content ◽  
Salt Weathering ◽  
Crack Network ◽  
Soil Microstructure ◽  
Confining Pressures ◽  
The Stability ◽  
Intact Loess

Influenced by both dry-wet cycles and salt weathering, the loess will exhibit significant changes in microstructure and permeability, which threatens the stability of loess slopes. Triaxial permeability tests and industrial computed tomography (CT) scans were carried out on saline intact loess with sodium sulfate. The relationship between permeability and pore structure of the loess after dry-wet cycles was discussed. Results show that the permeability coefficient of loess increases after dry-wet cycles, with the increment declining. After specified dry-wet cycles, the permeability coefficient increases approximately linearly with sodium sulfate content. However, the permeability coefficient significantly declines at higher confining pressures, while its attenuation rate decreases. An empirical relationship based on log 10 1 + e −     log 10 k was proposed to estimate the permeability coefficient of saline intact loess considering dry-wet cycles and salt content. Comparisons of measured and calculated results proved its rationality. CT scan images imply the damage to soil microstructure induced by dry-wet cycles and salt weathering, corresponding to the decline of the mean CT value (ME) and the increase of both crack ratio and fractal dimension of crack network.

scholarly journals Mutualistic strategies minimize coextinction in plant–disperser networks

2017 ◽  
Vol 284 (1854) ◽  
pp. 20162302 ◽  
Author(s):  
Evan C. Fricke ◽  
Joshua J. Tewksbury ◽  
Elizabeth M. Wandrag ◽  
Haldre S. Rogers
Keyword(s):  
Network Structure ◽  
Field Experiments ◽  
Empirical Relationship ◽  
Network Models ◽  
Mutualistic Interactions ◽  
Simulated Network ◽  
Direct And Indirect Impacts ◽  
Indirect Impacts ◽  
The Stability ◽  
Seed Dispersal Mutualism

The global decline of mutualists such as pollinators and seed dispersers may cause negative direct and indirect impacts on biodiversity. Mutualistic network models used to understand the stability of mutualistic systems indicate that species with low partner diversity are most vulnerable to coextinction following mutualism disruption. However, existing models have not considered how species vary in their dependence on mutualistic interactions for reproduction or survival, overlooking the potential influence of this variation on species' coextinction vulnerability and on network stability. Using global databases and field experiments focused on the seed dispersal mutualism, we found that plants and animals that depend heavily on mutualistic interactions have higher partner diversity. Under simulated network disruption, this empirical relationship strongly reduced coextinction because the species most likely to lose mutualists depend least on their mutualists. The pattern also reduced the importance of network structure for stability; nested network structure had little effect on coextinction after simulations incorporated the empirically derived relationship between partner diversity and mutualistic dependence. Our results highlight a previously unknown source of stability in mutualistic networks and suggest that differences among species in their mutualistic strategy, rather than network structure, primarily accounts for stability in mutualistic communities.

The influence of sodium sulfate and magnesium sulfate on the stability of bound chlorides in cement paste

2019 ◽  
Vol 228 ◽  
pp. 116775 ◽  
Author(s):  
Zhiqiang Yang ◽  
Jinyang Jiang ◽  
Xing Jiang ◽  
Song Mu ◽  
Meng Wu ◽  
...  
Keyword(s):  
Magnesium Sulfate ◽  
Cement Paste ◽  
Sodium Sulfate ◽  
The Stability

The Trial Research of Soil-Water Characteristic Curves of Unsaturated Soil and its Engineering Application

2012 ◽  
Vol 170-173 ◽  
pp. 3050-3053
Author(s):  
Cui Ran Liu ◽  
Jin Jun Guo
Keyword(s):  
Soil Water ◽  
Unsaturated Soil ◽  
Permeability Coefficient ◽  
Characteristic Curve ◽  
Engineering Application ◽  
Engineering Properties ◽  
Confining Pressures ◽  
Soil Water Characteristic Curves ◽  
Matrix Suction ◽  
Water Contents

With the improved triaxial equipment, the tests of research of the relationships between matrix suction and water content are performed And based on the test data, the curves between matrix suction and water contents under different confining pressures are drawn and the change rule between them are analyzed. And then the function between them is simulated out. Through the soil-water characteristic curve, the permeability coefficient of unsaturated soil can be calculated and the shear strength of unsaturated soil can be predicted. These results are important to research the engineering properties of unsaturated soil.

The Characteristics of Seepage Field and Numerical Analysis on the Stability of Reservoir Landslide

2012 ◽  
Vol 594-597 ◽  
pp. 2512-2519 ◽  
Author(s):  
Xiao Song Tang ◽  
Ying Ren Zheng ◽  
Yong Fu Wang
Keyword(s):  
Water Level ◽  
Permeability Coefficient ◽  
Underground Water ◽  
Strength Reduction ◽  
Seepage Field ◽  
Coupling Analysis ◽  
Reservoir Landslide ◽  
Water Level Changes ◽  
Quantitative Basis ◽  
The Stability

The stability of reservoir landslide would be influenced obviously by the fluctuation of water level, especially when the water descends, which is different from common landslide. Due to the unsteady seepage of underground water inside slope caused by the change of water level, the stability analysis of reservoir landslide through fluid-solid coupling is very complicated. At present, most people hold the view qualitatively that the less the permeability coefficient is and the faster the water level changes, the more unfavorable it is to the stability. This view lacks quantitative basis. Based on FEM strength reduction, the paper analyzes the influence of different sets of descending speed and permeability coefficient on the stability of reservoir landslide through fluid-solid coupling analysis. The paper also conducts the relevant analysis on the change of the characteristics of seepage field inside the slope, which provides basis for the study of the failure mechanism and the forecast of reservoir landslide.

Thermodynamic regime of greenstone metamorphism of basic volcanic rocks after experimental data

1981 ◽  
Vol 18 (8) ◽  
pp. 1303-1309 ◽  
Author(s):  
L. P. Pluysnina ◽  
I. P. Ivanov
Keyword(s):  
Stability Boundary ◽  
Salt Content ◽  
Volcanic Rocks ◽  
Fe Content ◽  
Low Salt ◽  
Thermodynamic Regime ◽  
Lower Temperature ◽  
The Stability ◽  
Basic Volcanic ◽  
Facies Transition

The stability fields of laumontite, prehnite, pumpellyite, zoisite, and tremolite-bearing assemblages were experimentally examined in the CaO–MgO–Al2O3–SiO2–H2O–CO2 system. The influence of the Fe content on the shift of the upper stability boundary towards both lower temperature and [Formula: see text] equilibrium values is shown for pumpellyite. The runs for some dehydration–carbonatization reactions in the complex H2O–CO2–NaCl fluid have revealed a decrease in the [Formula: see text] equilibrium values for even low salt content. The zeolite, prehnite–pumpellyite, and greenschist facies limits are plotted in the schematic [Formula: see text] diagram, and their possible Pfl limits are discussed. For examined P–T conditions of greenschist to amphibolite facies transition the absence of the compositional gap between tremolite and Ca-hornblende is found.

Searching Method of Potential Sliding Surfaces in the Rock Slope by Crack Network Simulation

2011 ◽  
Vol 368-373 ◽  
pp. 781-784
Author(s):  
Yong Zhang ◽  
De Xin Nie ◽  
Jiang Da He
Keyword(s):  
Rock Slope ◽  
Network Simulation ◽  
Rock Slopes ◽  
Crack Network ◽  
Sliding Surfaces ◽  
The Stability ◽  
Searching Method

In the process of evaluating the stability of some rock slopes, the discontinuities which mainly destroy the stability of future slope can not be understood and the locations of the slope can not be determined because of lacking of the exploration data. This paper determines the combination molds and the location of potential sliding surfaces using the method of crack network simulation to do statistics about all the discontinuities, which aims to resolving the problems of determining the locations and idiographic conformations of potential sliding surfaces in the rock slope.

scholarly journals Stability Analysis of Hydrodynamic Pressure Landslides with Different Permeability Coefficients Affected by Reservoir Water Level Fluctuations and Rainstorms

Water ◽  
2017 ◽  
Vol 9 (7) ◽  
pp. 450 ◽  
Author(s):  
Faming Huang ◽  
Xiaoyan Luo ◽  
Weiping Liu
Keyword(s):  
Water Level ◽  
Permeability Coefficient ◽  
Hydrodynamic Pressure ◽  
Water Level Fluctuations ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Stability Coefficient ◽  
Permeability Coefficients ◽  
Landslide Stability ◽  
The Stability

It is significant to study the variations in the stability coefficients of hydrodynamic pressure landslides with different permeability coefficients affected by reservoir water level fluctuations and rainstorms. The Sifangbei landslide in Three Gorges Reservoir area is used as case study. Its stability coefficients are simulated based on saturated-unsaturated seepage theory and finite element analysis. The operating conditions of stability coefficients calculation are reservoir water level variations between 175 m and 145 m, different rates of reservoir water level fluctuations, and a three-day continuous rainstorm. Results show that the stability coefficient of the hydrodynamic pressure landslide decreases with the drawdown of the reservoir water level, and a rapid drawdown rate leads to a small stability coefficient when the permeability coefficient ranges from 1.16 × 10−6 m/s to 4.64 × 10−5 m/s. Additionally, the landslide stability coefficient increases as the reservoir water level increases, and a rapid increase in the water level leads to a high stability coefficient when the permeability coefficient ranges from 1.16 × 10−6 m/s to 4.64 × 10−5 m/s. The landslide stability coefficient initially decreases and then increases as the reservoir water level declines when the permeability coefficient is greater than 4.64 × 10−5 m/s. Moreover, for structures with the same landslide, the landslide stability coefficient is most sensitive to the change in the rate of reservoir water level drawdown when the permeability coefficient increases from 1.16 × 10−6 m/s to 1.16 × 10−4 m/s. Additionally, the rate of decrease in the stability coefficient increases as the permeability coefficient increases. Finally, the three-day rainstorm leads to a significant reduction in landslide stability, and the rate of decrease in the stability coefficient initially increases and then decreases as the permeability coefficient increases.

A Novel pH-Sensitive Microsphere Composed of CM-Chitosan and Alginate for Sulforaphane Delivery

2011 ◽  
Vol 687 ◽  
pp. 539-547 ◽  
Author(s):  
Hui Wang ◽  
Hao Liang ◽  
Qi Peng Yuan ◽  
Tian Xin Wang
Keyword(s):  
Sodium Sulfate ◽  
Anticancer Agent ◽  
Ph Sensitive ◽  
Water Soluble ◽  
Ph Values ◽  
Swelling Studies ◽  
The Stability ◽  
Carboxymethylated Chitosan

Sulforaphane (SF) has been proved to be an effective anticancer agent according to its experiments bothin vitroandin vivo. To date, there is few reported method to deliver SF for increasing its bioactivity and stability. In this study, a novel pH-sensitive microsphere composed of water-soluble carboxymethylated chitosan (CMCS) and alginate mixed with sodium sulfate was developed for SF delivery. Swelling studies and release characteristics under different pH values of microspheres were investigated. Then, the release of SF from test microspheres was studied in simulated gastric and segmented intestinal media. It has been found that the SF cumulated release in 5h was increased from 55.89% to 76.73% when the microspheres mixed with sodium sulfate. In addition, the stability of SF embedded in CMCS/alginate microspheres was also significantly improved. Under pH 7.4, free SF had a severe degradation of approximate 100% within 210 min, whereas the change of the SF in microspheres was only a decrease of about 10%. The results suggested that the microspheres of CMCS and alginate could be a suitable pH-sensitive carrier to increase the stability of SF in the segmented intestine.

scholarly journals Estimators of the Impact of Climate Change in Salt Weathering of Cultural Heritage

Geosciences ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 401 ◽  
Author(s):  
Beatriz Menéndez
Keyword(s):  
Climate Change ◽  
Sodium Chloride ◽  
Cultural Heritage ◽  
Sodium Sulfate ◽  
Calcium Sulfate ◽  
Phase Changes ◽  
Salt Weathering ◽  
Sodium Calcium ◽  
Calcium Magnesium ◽  
The Impact

Changes induced by climate change in salt weathering of built cultural heritage are estimated in different ways, but generally as a function of phase changes phenomena of two common salts, sodium chloride and sodium sulfate. We propose to use not only these salts, but also other common salts as calcium sulfate, or mixtures of chlorides, sulfates, and nitrates of sodium, calcium, magnesium, and potassium. Comparisons between the predicted changes in salt weathering obtained for single salts and for combinations of different salts are presented. We applied the proposed methodology to 41 locations uniformly distributed in France. The results show that estimations of actual and evolution of future weathering depend on the selected salt or combination of salts. According to our results, when using a combination of different salts, weathering evolution is less favorable (more damage in the future) than when using a single salt.

scholarly journals Temperature and Salt Content Regimes in Three Shallow Ice-Covered lakes

1997 ◽  
Vol 28 (2) ◽  
pp. 99-128 ◽  
Author(s):  
J. Malm ◽  
A. Terzhevik ◽  
L. Bengtsson ◽  
P. Boyarinov ◽  
A. Glinsky ◽  
...  
Keyword(s):  
Salt Content ◽  
Heat Content ◽  
Bottom Layer ◽  
Stable Stratification ◽  
Ice Formation ◽  
Vertical Temperature ◽  
Temperature Of Maximum Density ◽  
The Stability ◽  
Horizontal Variations ◽  
Density Regime

A field study on the temperature, salt content, and density regime in three shallow ice-covered Karelian lakes is presented. The measurements show that the heat content increases during the whole ice-covered period. At ice formation a weak stable stratification existed in the lakes, with average temperatures about 1°C. Thereafter, the stability of the stratification gradually increased, mainly due to pronounced temperature increases in the bottom layers. In mid-winter the bottom layer in the deep parts of the lakes obtained temperatures above 4°C. The density stratification in these layers was stable, however, due to higher salt contents (increasing continuously during the winter) in the vicinity of the bottom. The horizontal variations in temperature and salt content were very small, and both parameters can be considered to be horizontally homogeneous. Under-ice convection was developed in two of the three investigated lakes during the second half of April, when heating due to penetrating solar radiation became apparent. Although no under-ice convection in the conventional sense occurred in the third lake (Uros), interior convection developed when the temperature exceeded 4°C (the temperature of maximum density) there. The absence of under-ice convection in Lake Uros is most likely due to the higher vertical temperature gradient in the lake before spring heating and smaller extinction coefficient than in the other two lakes.

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