scholarly journals The Influence of Regional Freeze–Thaw Cycles on Loess Landslides: Analysis of Strength Deterioration of Loess with Changes in Pore Structure

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3047
Author(s):  
Zuyong Li ◽  
Gengshe Yang ◽  
Hui Liu
Keyword(s):  
Pore Structure ◽  
Triaxial Compression ◽  
Strength Loss ◽  
Loess Landslide ◽  
Strength Deterioration ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Loess Landslides ◽  
The Stability

The loess landslide in Gaoling District of Xi’an, Shaanxi in China is closely related to the seasonal freeze–thaw cycle, which is manifested by the destruction of pore structure and strength deterioration of the loess body under freeze–thaw conditions. In order to study the relationship between macro-strength damage and pore structure deterioration of saturated loess under freeze–thaw conditions and its influence on the stability of landslides, this paper explores the effect of freeze–thaw cycles on the strength of saturated undisturbed loess through triaxial compression test, and explores the micro-microstructure changes of saturated undisturbed loess through scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). This is to analyze the evolution of the pore structure and strength loss evolution of saturated loess during the freeze–thaw process, and to describe the freeze–thaw damage of saturated undisturbed loess through the change of porosity and strength deterioration. Then, the internal correlation expression between the porosity change and the strength degradation is established to realize the verification analysis of the test data based on the correlation model. The research results show that: (1) As the number of freeze–thaw cycles increases, the peak strength loss rate gradually increases, and the strength deterioration of saturated loess becomes more and more obvious. (2) The freeze–thaw cycle will lead to the development of pores and cracks in the sample, accompanied by the generation of new cracks, which will cause the deterioration of the pore structure of the sample as a whole. (3) The response of strength damage and porosity deterioration of saturated undisturbed loess is roughly similar under the freeze–thaw cycle. The change in porosity can be measured to better reflect the strength deterioration of saturated loess. Therefore, the change of pore structure of undisturbed loess under freeze–thaw cycle conditions is tested by field sampling and indoor tests to reflect the phenomenon of strength deterioration, thereby analyzing the stability of loess slopes.

scholarly journals Effect of freeze–thaw cycle on physical and mechanical properties and damage characteristics of sandstone

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Longxiao Chen ◽  
Kesheng Li ◽  
Guilei Song ◽  
Deng Zhang ◽  
Chuanxiao Liu
Keyword(s):  
Mechanical Properties ◽  
Shear Failure ◽  
Triaxial Compression ◽  
Physical And Mechanical Properties ◽  
Freeze Thaw ◽  
Damage Characteristics ◽  
Large Pore ◽  
Natural Rock ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

AbstractRock deterioration under freeze–thaw cycles is a concern for in-service tunnel in cold regions. Previous studies focused on the change of rock mechanical properties under unidirectional stress, but the natural rock mass is under three dimensional stresses. This paper investigates influences of the number of freeze–thaw cycle on sandstone under low confining pressure. Twelve sandstone samples were tested subjected to triaxial compression. Additionally, the damage characteristics of sandstone internal microstructure were obtained by using acoustic emission (AE) and mercury intrusion porosimetry. Results indicated that the mechanical properties of sandstone were significantly reduced by freeze–thaw effect. Sandstone’ peak strength and elastic modulus were 7.28–37.96% and 6.38–40.87% less than for the control, respectively. The proportion of super-large pore and large pore in sandstone increased by 19.53–81.19%. We attributed the reduced sandstone’ mechanical properties to the degenerated sandstone microstructure, which, in turn, was associated with increased sandstone macropores. The macroscopic failure pattern of sandstone changed from splitting failure to shear failure with an increasing of freeze–thaw cycles. Moreover, the activity of AE signal increased at each stage, and the cumulative ringing count also showed upward trend with the increase of freeze–thaw number.

The Effect of Freeze/Thaw Cycles on the Stability of Compounds in DMSO

2003 ◽  
Vol 8 (2) ◽  
pp. 210-215 ◽  
Author(s):  
Barbara A. Kozikowski ◽  
Thomas M. Burt ◽  
Debra A. Tirey ◽  
Lisa E. Williams ◽  
Barbara R. Kuzmak ◽  
...  
Keyword(s):  
High Throughput Screening ◽  
High Performance ◽  
Atmospheric Conditions ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Time Period ◽  
Freeze Thaw Cycle ◽  
Low Humidity ◽  
The Stability ◽  
Short Time

A diverse set of 320 compounds from the Procter & Gamble Pharmaceuticals organic compound repository was prepared as 20-mM DMSO solutions and stored at 4°C under argon in pressurized canisters to simulate a low-humidity environment. The plates were subjected to 25 freeze/thaw cycles while being exposed to ambient atmospheric conditions after each thaw to simulate the time and manner by which compound plates are exposed to the atmosphere during typical liquid-handling and high-throughput screening processes. High-performance liquid chromatography–mass spectrometry with evaporative light-scattering detection was used to quantitate the amount of compound remaining after every 5th freeze/thaw cycle. Control plates were stored either at room temperature under argon or at 4°C under argon without freeze/thaw cycling and were evaluated at the midpoint and the endpoint of the study. The study was conducted over a short time period (i.e., 7 weeks) to minimize the effect of compound degradation over time due to the exposure of the compounds to DMSO.The results from this study will be used to determine the maximum number of freeze/thaw cycles that can be achieved while maintaining acceptable compound integrity.(Journal of Biomolecular Screening 2003:210-215)

scholarly journals Stability of Plasma Amyloid-β 1–40, Amyloid-β 1–42, and Total Tau Protein over Repeated Freeze/Thaw Cycles

2020 ◽  
Vol 10 (1) ◽  
pp. 46-55
Author(s):  
Huei-Chun Liu ◽  
Ming-Jang Chiu ◽  
Chin-Hsien Lin ◽  
Shieh-Yueh Yang
Keyword(s):  
Tau Protein ◽  
Statistical Significance ◽  
Amyloid Β ◽  
Freeze Thaw ◽  
Total Tau ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Fresh Plasma ◽  
The Stability ◽  
T Tau

Introduction: Blood biomarkers of Alzheimer’s disease (AD) have attracted much attention of researchers in recent years. In clinical studies, repeated freeze/thaw cycles often occur and may influence the stability of biomarkers. This study aims to investigate the stability of amyloid-β 1–40 (Aβ1–40), amyloid-β 1–42 (Aβ1–42), and total tau protein (T-tau) in plasma over freeze/thaw cycles. Methods: Plasma samples from healthy controls (n = 2), AD patients (AD, n =3) and Parkinson’s disease patients (PD, n = 3) were collected by standardized procedure and immediately frozen at –80°C. Samples underwent 5 freeze/thaw (–80°C/room temperature) cycles. The concentrations of Aβ1–40, Aβ1–42, and T-tau were monitored during the freeze/thaw tests using an immunomagnetic reduction (IMR) assay. The relative percentage of concentrations after every freeze/thaw cycle was calculated for each biomarker. Results: A tendency of decrease in the averaged relative percentages over samples through the freeze and thaw cycles for Aβ1–40 (100 to 97.11%), Aβ1–42 (100 to 94.99%), and T-tau (100 to 95.65%) was found. However, the decreases were less than 6%. For all three biomarkers, no statistical significance was found between the levels of fresh plasma and those of the plasma experiencing 5 freeze/thaw cycles (p > 0.1). Conclusions: Plasma Aβ1–40, Aβ1–42, and T-tau are stable through 5 freeze/thaw cycles measured with IMR.

scholarly journals The Effects of a Single Freeze-Thaw Cycle on Concentrations of Nutritional, Noncommunicable Disease, and Inflammatory Biomarkers in Serum Samples

2021 ◽  
Author(s):  
Ransi Ann Abraham ◽  
Garima Rana ◽  
Praween K. Agrawal ◽  
Robert Johnston ◽  
Avina Sarna ◽  
...  
Keyword(s):  
Large Scale ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Noncommunicable Disease ◽  
Noncommunicable Diseases ◽  
Serum Samples ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
The Stability

Abstract Background The stability of biological samples is vital for reliable measurements of biomarkers in large-scale survey settings, which may be affected by freeze-thaw procedures. We examined the effect of a single freeze-thaw cycle on 13 nutritional, noncommunicable diseases (NCD), and inflammatory bioanalytes in serum samples. Method Blood samples were collected from 70 subjects centrifuged after 30 minutes and aliquoted immediately. After a baseline analysis of the analytes, the samples were stored at − 70°C for 1 month and reanalyzed for all the parameters. Mean percentage differences between baseline (fresh blood) and freeze-thaw concentrations were calculated using paired sample t-tests and evaluated according to total allowable error (TEa) limits (desirable bias). Results Freeze-thaw concentrations differed significantly (p < 0.05) from baseline concentrations for soluble transferrin receptor (sTfR) (− 5.49%), vitamin D (− 12.51%), vitamin B12 (− 3.74%), plasma glucose (1.93%), C-reactive protein (CRP) (3.45%), high-density lipoprotein (HDL) (7.98%), and cholesterol (9.76%), but they were within respective TEa limits. Low-density lipoprotein (LDL) (− 0.67%), creatinine (0.94%), albumin (0.87%), total protein (1.00%), ferritin (− 0.58%), and triglycerides (TAG) (2.82%) concentrations remained stable following the freeze-thaw cycle. In conclusion, single freeze-thaw cycle of the biomarkers in serum/plasma samples after storage at − 70°C for 1 month had minimal effect on stability of the studied analytes, and the changes in concentration were within acceptable limit for all analytes.

Phenotyping of Hyperlipoproteinemias

1970 ◽  
Vol 16 (6) ◽  
pp. 507-511 ◽  
Author(s):  
James Winkelman ◽  
Donald R Wybenga ◽  
Frank A Ibbott
Keyword(s):  
Cellulose Acetate ◽  
Room Temperature ◽  
Cellulose Acetate Electrophoresis ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
The Stability

Abstract The stability of serum specimens collected for cellulose acetate electrophoresis of lipoproteins has been studied for each of the hyperlipoproteinemia phenotypes. In general, samples kept at room temperature for three days are still suitable for analysis. On longer standing, artifacts can cause misinterpretation of strips, or render them completely unreadable. If specimens are stored at refrigerator or freezer temperatures, deterioration is retarded but the period of stability after they are returned to room temperature is unaltered. A second freeze-thaw cycle makes specimens unsuitable for analysis. Samples can be stored at refrigerator temperatures for at least 28 days and at freezer temperatures for at least 14 days if one freeze-thaw cycle is used.

scholarly journals Investigation and Preparation of the Plastering Mortar for Autoclaved Aerated Blocks Walls

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 175
Author(s):  
Tao Feng ◽  
Lingling Xu ◽  
Xin Shi ◽  
Jian Han ◽  
Pan Zhang
Keyword(s):  
Water Absorption ◽  
Hydroxypropyl Methylcellulose ◽  
Ethylene Vinyl Acetate ◽  
Strength Loss ◽  
High Water ◽  
Dry Density ◽  
Pore Characteristics ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

The increase in the use of aerated concrete blocks (AAB) in construction walls has increased the demand for specialized plastering mortar, which should have the characteristics of high water retention, low water absorption, low thermal conductivity and high toughness. This study scrutinized the potential of expanded and vitrified small ball (EVSB) and expanded perlite as lightweight aggregates, and the beneficial effect of a modifying additive based on a mixture of ethylene-vinyl acetate (EVA), hydroxypropyl methylcellulose (HPMC) and fibers has been proved. The dry density, consistency, water absorption, mechanical strength, pore characteristics and micro morphology of the plaster mortar were evaluated. It is manifested by enhanced toughness, reduced dry density, and optimized pore structure characteristics. The relationship between mass water absorption and freeze-thaw cycle resistance is established, which shows that when the mass water absorption is 20%, the mortar exhibits better freeze resistance. After 25 freeze-thaw cycle tests, the mass loss was 0.26% and the strength loss was 1.41%. Through the comparison of test results, a new composition of plastering mortar is provided: cement: fly ash: water: heavy calcium carbonate: quartz sand: EVSB: EVA: HPMC (100,000 mPa·s): fiber = 70: 30: 76: 12: 250: 24: 2: 0.3: 0.2.

scholarly journals Mechanical Properties and Micro Structure of Cement Concrete in Freeze-Thaw Environment

2021 ◽  
Vol 233 ◽  
pp. 01011
Author(s):  
Xin jian Lv ◽  
Lei Yu ◽  
Ming ming Chai
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Pore Structure ◽  
Fresh Water ◽  
Pore Diameter ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw ◽  
Salty Water ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

In order to find the declay law of mechanical property and the performance difference after salty water and fresh water freeze-thaw cycle, freeze-thaw cycle environments under the salty water and fresh water are simulated. The compressive strength, dynamic elastic modulus and the mass lost are tested. The pore structure parameters are also tested by MIP. Plot the pore diameter distribution curve. The result shows that the compressive strength and dynamic elastic modulus are all decreased. The degree of these two properties decreasing under salty water freeze and thaw recycle is more than the one under fresh water. The parameters of porosity and critical pore diameter become larger. The amount of pores whose diameter is between 100nm and 1000nm increase. The amount of pores whose diameter is under 100nm decrease. The deteriorate degree of pore structure is deeper in salty water than in fresh water.

Experimental Research on a New-Type Concrete Antifreeze

2011 ◽  
Vol 148-149 ◽  
pp. 1209-1213
Author(s):  
Bao Min Wang ◽  
Kai Song ◽  
Ni Tu
Keyword(s):  
Compressive Strength ◽  
Loss Rate ◽  
Performance Test ◽  
Setting Time ◽  
Strength Loss ◽  
Freeze Thaw ◽  
Performance Indexes ◽  
Thaw Cycle ◽  
Basic Performance ◽  
Freeze Thaw Cycle

Basic performance test was performed on a newly-developed compound antifreeze and experiment was carried out to study the basic performance, mechanical property and durability of the concrete mixtures containing 0%, 4% and 5% antifreeze. The result shows the antifreeze may be used for the concrete construction at 20°C below zero and it has favorable performance for winter construction. When the amount to be added is 4% and 5%, the ratio of compressive strength of 28 days shall be 105% and 107% respectively; the ratio of compressive strength of 56 days shall be 114% and 112% respectively. In freeze-thaw cycle experiment, 50 times of freeze-thaw strength loss rate is 45.3% and 44.8% of the strength loss rate of the concrete without the antifreeze. The water-reducing ratio of the antifreeze, ratio of bleeding rate, air content, difference in setting time, strength ratio, ratio of shrinkage, permeated height ratio and other performance indexes all satisfy specification requirements.

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