The Influence of Drying-Wetting Cycles on the Suction Stress of Compacted Loess and the Associated Microscopic Mechanism

To better understand and analyze the unsaturated stability of loess filling body, it is necessary to study the changes in suction stress before and after the drying-wetting cycles. In this study, the SWCC of compacted loess before and after drying-wetting cycles was tested using the filter paper method. Then, the suction stress was calculated and the microstructure of the loess sample was determined by the SEM and NMR. The results showed that the drying-wetting cycles had an important influence on the SSCC and microstructure of compacted loess. The change in suction stress before and after the drying-wetting cycles can be well explained by the loess microstructure. The drying-wetting cycles did not significantly change the basic trend of the compacted loess’s SSCC, but it increased the porosity and the dominant pore diameter of loess, and reduced the suction stress under the same matric suction. The main significant change in suction stress with matric suction occurred within the range of the dominant soil pores. The larger the dominant pore diameter, the smaller the suction stress under the same matric suction. In addition, this study proposes a new method for calculating suction stress based on the PSD parameters.

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The Influence of Drying-Wetting Cycles on the Suction Stress of Compacted Loess and the associated Microscopic Mechanism

10.21203/rs.3.rs-317088/v1 ◽

2021 ◽

Author(s):

Yongpeng Nie ◽

Wan kui Ni ◽

Xiangning Li ◽

Haiman Wang ◽

Kangze Yuan ◽

...

Keyword(s):

Characteristic Curve ◽

Calculation Methods ◽

Microscopic Mechanism ◽

Suction Stress ◽

Dominant Soil ◽

Before And After ◽

Matrix Suction ◽

Soil Pores ◽

Paper Method ◽

Compacted Loess

Abstract In order to better understand and analyze the unsaturated stability of loess fillings, it is necessary to study the changes in suction stress before and after the drying-wetting cycles. In this study, the soil-water characteristic curve (SWCC) of compacted loess before and after drying-wetting cycles was tested using the filter paper method. Then, the suction stress was calculated and the microstructure of the loess sample was determined by the scanning electron microscope（SEM）and nuclear magnetic resonance (NMR). The results showed that the drying-wetting cycles had an important influence on the suction stress characteristic curve (SSCC) and microstructure of compacted loess. The change in suction stress before and after the drying-wetting cycles can be explained by the loess microstructure. The drying-wetting cycles did not significantly change the basic trend of the compacted loess's suction stress, but it increased the porosity and the diameter of the dominant pore (i.e., the inter-aggregate pore) of the sample, and reduced the suction stress when the same matrix suction was applied. The main significant change in suction stress with matrix suction occurred within the range of the dominant soil pores. The larger the diameter of the dominant pore, the smaller the suction stress under the same matrix suction. In addition, this study also proposes a new method for calculating suction stress based on the pore size distribution（PSD） parameters, which is more convenient than traditional calculation methods based on SWCC parameters.

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The Water Retention Characteristics of an Unsaturated Compacted Loess Material

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.703.396 ◽

2016 ◽

Vol 703 ◽

pp. 396-399

Author(s):

Zhi Hu ◽

Zheng Lu ◽

Hai Lin Yao

Keyword(s):

Filter Paper ◽

Water Retention ◽

Water Retention Curve ◽

Combined Method ◽

Retention Curve ◽

Osmotic Suction ◽

Retention Characteristics ◽

Paper Method ◽

Compacted Loess ◽

Natural Loess

The water retention curve of an unsaturated compacted loess material has been obtained by combining the filter paper method, the vapour equilibrium method and the axis translation method. It was indicated that the combined method is efficient to investigate the water retention characteristics of compacted loess materials. The results showed that the osmotic suction in the compacted loess varies slightly with the increasing water content. Higher matric suction occurs in the compacted loess compared with the natural loess at the same moisture.

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Factors Affecting the Filter Paper Method for Total and Matric Suction Measurements

Geotechnical Testing Journal ◽

10.1520/gtj11094j ◽

2002 ◽

Vol 25 (3) ◽

pp. 8198 ◽

Cited By ~ 10

Author(s):

L David Suits ◽

TC Sheahan ◽

EC Leong ◽

L He ◽

H Rahardjo

Keyword(s):

Filter Paper ◽

Matric Suction ◽

Factors Affecting ◽

Filter Paper Method ◽

Paper Method

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Efficacy of Bacillus thuringiensis (Berliner) isolates on fig moth, Ephestia cautella (Walker) Larvae

Baghdad Science Journal ◽

10.21123/bsj.11.2.943-951 ◽

2014 ◽

Vol 11 (2) ◽

pp. 943-951

Author(s):

Baghdad Science Journal

Keyword(s):

Bacillus Thuringiensis ◽

Larval Stage ◽

Filter Paper ◽

Larval Instar ◽

Ephestia Cautella ◽

Larval Stages ◽

The Third ◽

Total Percentage ◽

First Instar ◽

Paper Method

The following dilution 5×10-1, 10-1, 10?2 , 10-3 gm/L for the indigenous isolate of Bacillus thuringiensis bacteria and the commercially isalate were used for experiments against the different stages of fig moth of E.cautella which exposed by filter paper method. The results showed that mortality of larval stages was increased with the increasing concentration of the biocide, in addition to increase in the mortality of the larval stages reached to the highest percentage in the third days of treatment of the larval stage in comparison with the first and second days of exposure. The results also showed that the sensitivity of larval stages was increased in first and second instars while reduced in the last instars .The high percentage of first instar mortality for the indigenous isolate in the concentration of 5×10-1 was 72.8% , while the low percentage of mortality showed in the concentration of 5×10-1 for the fifth instar larvae which was 13.3% in third days of treatment while a high percentage of mortality was showed for the first instar larvae for the commercially isulate in the concentration of 5×10-1 was 59.4% Furthermore, low percentage of mortality was shown in the concentration of 5×10-1 in fifth instar larval which was 8.3% in the third days of treatment. The results also showed that the indigenous isolated was more effective than the commercially produced bacteria for killing larval instars of fig moth E.cautella .The total percentage of larval instar mortality reached to 44.5 % after the third days of treatment in concentration 5×10-1 in the indigenous isolate , and it was 33.8 % in the commercially produced bacteria .

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Determination of water retention characteristics of organic soils, using the indirect filter-paper method

Acta Scientiarum Polonorum Formatio Circumiectus ◽

10.15576/asp.fc/2018.17.2.13 ◽

2018 ◽

Vol 2 ◽

pp. 13-21

Author(s):

Ryszard Oleszczuk ◽

◽

Ewelina Zając ◽

Edyta Hewelke ◽

Karolina Wawer ◽

...

Keyword(s):

Filter Paper ◽

Water Retention ◽

Organic Soils ◽

Filter Paper Method ◽

Retention Characteristics ◽

Paper Method

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Evaluation of the Common Bed Bug, Cimex lectularius (Insecta: Hemiptera: Cimicidae) Susceptibility to λ-Cyhalothrin, Malathion, and Diazinon in Northeastern Iran

Journal of Medical Entomology ◽

10.1093/jme/tjz011 ◽

2019 ◽

Vol 56 (4) ◽

pp. 903-906 ◽

Cited By ~ 1

Author(s):

Fariba Berenji ◽

Ali Moshaverinia ◽

Abbas Jadidoleslami ◽

Aliakbar Shamsian ◽

Stephen L Doggett ◽

...

Keyword(s):

Filter Paper ◽

Cimex Lectularius ◽

Bed Bugs ◽

Bed Bug ◽

Response Data ◽

Blood Sucking ◽

Mashhad City ◽

The Common ◽

Student Residence ◽

Paper Method

Abstract The common bed bug, Cimex lectularius (Linnaeus 1758), is a nocturnal blood-sucking ectoparasite of humans that is highly prevalent in the northeast of Iran. In recent years, the efficacy of those insecticides that have been frequently used to control bed bugs in Iran has not been studied. Due to frequent complaints about bed bug treatment failures in Mashhad city (northeastern Iran), this study assessed the susceptibility of C. lectularius collected from a student residence hall to Diazinon, Malathion, and λ-cyhalothrin. The desired concentrations of each insecticide were prepared in acetone, and bioassays were performed using insecticide-impregnated filter paper method. The concentration–response data were subjected to POLO-PC software and data were analyzed by the log-probit procedure. The LC50 values of Diazinon and λ-cyhalothrin for examined bed bugs were 1,337.40 and 2,022.36 ppm, respectively. Malathion at the highest concentration (10,000 ppm) did not exhibit any toxicity to examined C. lectularius. Comparing these results to the same previous studies showed that susceptibility of examined bed bugs to these insecticides has been highly decreased. This study revealed an occurrence of insecticide resistance in bed bug populations in northeastern Iran. It also suggests that Malathion, Diazinon, and λ-cyhalothrin are ineffective against bed bugs in this region.

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Evaluation of iron oxide impregnated filter paper method as an index of phosphorus availability in paddy soils of Tanzania

Nutrient Cycling in Agroecosystems ◽

10.1007/s10705-006-9054-6 ◽

2006 ◽

Vol 77 (2) ◽

pp. 169-177 ◽

Cited By ~ 4

Author(s):

C. Y. Shekiffu ◽

J. M. R. Semoka

Keyword(s):

Iron Oxide ◽

Filter Paper ◽

Phosphorus Availability ◽

Paddy Soils ◽

Filter Paper Method ◽

Paper Method

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DETERMINATION OF SELECTIVE ACTION OF FUNGICIDES ON THE MICROFLORA OF BARLEY SEED

Canadian Journal of Plant Science ◽

10.4141/cjps68-112 ◽

1968 ◽

Vol 48 (6) ◽

pp. 587-594 ◽

Cited By ~ 8

Author(s):

J. T. Mills ◽

H. A. H. Wallace

Keyword(s):

Filter Paper ◽

Seed Treatment ◽

Barley Seed ◽

Cochliobolus Sativus ◽

Selective Action ◽

Streptomyces Spp ◽

Specific Effects ◽

Treated Seed ◽

Paper Method

The effects of 47 seed treatment fungicides on the microflora of barley seed that was naturally infested 95–100% with Cochliobolus sativus and other fungi were investigated after 7 days on moist filter paper. Each fungicide had a characteristic and reproducible effect on these organisms. Fungicides containing mercury or maneb were highly effective against all organisms, whereas specific effects were associated with other fungicides. Least survival (best control) of C. sativus was obtained with Ceresan M, Pandrinox APX and Panogen PX among the mercurials, and Green Cross SWF 850 and SWF 860, Chemagro 4497 and Chipman 53-64 among the non-mercurials. The incidence of Acremoniella sp. detected was high on seed treated with Dexon, Cephalosporium sp. with Vitavax, Streptomyces spp. with Green Cross SWF 850, and Cladosporium spp. with Green Cross 3922. It is suggested that the data obtained by the filter paper method should be complementary to those obtained from treated seed after 7 days in soil.

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