scholarly journals Glacial and Periglacial Transformation of Palaeokarst in the Lublin-Volhynia Region (Se Poland, NW Ukraine) on the Base of TL Dating

2007 ◽  
Vol 27 (-1) ◽  
pp. 41-46 ◽  
Author(s):  
Radosław Dobrowolski ◽  
Stanisław Fedorowicz
Keyword(s):  
Genetic Relationship ◽  
Experimental Investigations ◽  
Considerable Influence ◽  
Freezing And Thawing ◽  
Tl Dating ◽  
Freeze Thaw ◽  
Se Poland ◽  
Repeated Freezing ◽  
Formation Conditions ◽  
Close Genetic Relationship

Glacial and Periglacial Transformation of Palaeokarst in the Lublin-Volhynia Region (Se Poland, NW Ukraine) on the Base of TL Dating Distinctly diverse results of TL dating are obtained for the deposits with similar lithofacial features but filling morphologically differentiated karst palaeoforms (dolines, pipes, pockets). The infillings of dolines and pipes are mostly of the Saalian age. Based on sedimentological analysis, their formation conditions are related to sub- or/and terminoglacial environment. The age obtained for all infillings of pockets is underestimated in comparison with lithostratigraphic data. A close genetic relationship between these forms and periglacial conditions seems to indicate that the reduction of TL signal is mostly influenced by the disintegration of grains resulted from the repeated freezing and thawing of glaciogenic deposits. A considerable influence of frost weathering on the decrease of thermoluminescence intensity of mineral grains is indirectly confirmed by the results of experimental investigations consisting in the repeated TL measurements of pockets' infillings after successive freeze-thaw cycles.

scholarly journals Mechanical Properties of Sandstone Cement-Stabilized Macadam

2019 ◽  
Vol 9 (17) ◽  
pp. 3460 ◽  
Author(s):  
Qiang Du ◽  
Ting Pan ◽  
Jing Lv ◽  
Jie Zhou ◽  
Qingwei Ma ◽  
...  
Keyword(s):  
Cement Content ◽  
Influence Factors ◽  
Road Construction ◽  
Experimental Investigations ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Test Pieces ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Brazilian Splitting

Application of sandstone in cement-stabilized macadam (CSM) is an effective way to utilize sandstone. To determine the feasibility of using sandstone as a CSM aggregate, a series of experimental investigations, such as unconfined compressive strength (UCS) tests, Brazilian splitting tests and freeze-thaw cycle tests, were conducted on sandstone cement-stabilized macadam (SCSM). Three mixed variables, covering the cement content, aggregate type and curing period, were set as influence factors. The testing results indicated that the UCS, indirect tensile strength (ITS) and frost resistance property of the test-pieces increased with cement content and curing age. Considering the asphalt pavement design specifications for China, the UCS and ITS values of the SCSM complied with the requirements of light traffic road construction before freeze-thaw cycles. However, the SCSM subjected to freezing and thawing meets the requirements only when the cement content is 4.5%. Therefore, it is noteworthy that CSM containing sandstone aggregates should be applied with caution in cold region because of insufficient freeze resistance.

FREEZE-THAW EFFECTS ON GRANULAR STRUCTURE REORGANIZATION FOR SOIL MATERIALS OF VARYING TEXTURE AND MOISTURE CONTENT

1988 ◽  
Vol 68 (3) ◽  
pp. 485-494 ◽  
Author(s):  
S. PAWLUK
Keyword(s):  
Moisture Content ◽  
Lacustrine Sediments ◽  
Field Capacity ◽  
Granular Structure ◽  
Glacial Till ◽  
Microstructural Development ◽  
Clay Loam ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Repeated Freezing

Repeated freezing and thawing of glacial till cores of clay loam texture results in the formation of granic and metafragmic microfabrics. These units of fabric are best developed near the surface of cores kept at moisture levels between field capacity and saturation. Well-sorted lacustrine sediments with fewer voids tend to form banded fabrics. Many of the morphological features such as vesicles, metavughs and desiccation cracks commonly attributed to freeze-thaw processes are evident in all materials tested. Discrete units of fabric observed in this study are very similar to units of fabric observed in the Ah horizons of Black Chernozemic and Cryosolic soils. Results of this investigation strongly support earlier research which suggests that frost processes are major contributors to their microstructural development. Key words: Granic, freeze-thaw, microfabrics

Inactivation of a Cold-Induced Putative RNA Helicase Gene of Listeria monocytogenes Is Accompanied by Failure To Grow at Low Temperatures but Does Not Affect Freeze-Thaw Tolerance

2010 ◽  
Vol 73 (8) ◽  
pp. 1474-1479 ◽  
Author(s):  
REHA O. AZIZOGLU ◽  
S. KATHARIOU
Keyword(s):  
Listeria Monocytogenes ◽  
Normal Growth ◽  
Rna Helicase ◽  
Soft Agar ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Transposon Insertion ◽  
Helicase Gene ◽  
Repeated Freezing ◽  
Cold Sensitive

Freeze-thaw tolerance (cryotolerance) of Listeria monocytogenes is markedly influenced by temperature of growth of the bacteria, and may involve responses to low-temperature stresses encountered during freezing and thawing. A cold-sensitive mariner-based transposon mutant of L. monocytogenes F2365 was found to harbor a single insertion in LMOf2365_1746, encoding a putative RNA helicase, and earlier shown by other investigators to be induced during 4°C growth of L. monocytogenes. The mutant had normal growth at 37°C but completely failed to grow at either 4 or 10°C, and had impaired growth and reduced swarming on soft agar at 25°C. However, the mutation had no discernible influence on the ability of the bacteria to tolerate repeated freezing and thawing after growth at either 25 or 37°C. The findings suggest that the transposon insertion in the putative helicase gene, in spite of the severely cold-sensitive phenotype that accompanies it, does not affect the ability of the bacteria to cope with cold-related stresses encountered during repeated freezing and thawing.

Freeze/thaw stability of transferrin, and reference values obtained with kinetic nephelometry.

1984 ◽  
Vol 30 (1) ◽  
pp. 114-115 ◽  
Author(s):  
L Stoddard ◽  
W Dennis ◽  
R M Parvin ◽  
O W van Assendelft
Keyword(s):  
Reference Values ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Normal Reference ◽  
Repeated Freezing ◽  
Blood Specimens ◽  
Normal Adults

Abstract To determine whether transferrin is stable to repeated freezing and thawing, we used blood specimens from 100 normal adults. Their transferrin concentrations were determined by a laser kinetic nephelometric immunoassay. The sera were stored at 4 degrees C and analyzed the next day (day 1). Specimens 1-25 were stored at -20 degrees C and assayed again on days 3, 4, 8, 16, 22, and 43. Specimens 26-100 were stored at 4 degrees C and analyzed again on day 2. Transferrin proved to be stable to repeated freezing and thawing. Normal reference values with respect to sex and age are given, as determined with the Baker 420 Immunological Nephelometer.

scholarly journals PSIV-25 Effect of Various Handling Methods of Plasma and Serum Samples on Pregnancy Associated Glycoprotein Concentrations

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 289-290
Author(s):  
Grace M Wesson ◽  
Lohana Fernandez ◽  
Rebecca K Poole ◽  
Gessica A Franco ◽  
Sydney T Reese ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Plasma Samples ◽  
Freezing And Thawing ◽  
Serum Samples ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Repeated Freezing ◽  
Pregnancy Status ◽  
Handling Methods

Abstract Pregnancy associated glycoproteins (PAG) can be used as a biomarker for early pregnancy diagnosis, so accurate and consistent PAG detection is critical. The objective of this study was to determine if plasma and serum PAG concentrations were altered when centrifugation occurred at different times post-collection, when subjected to repeated freezing and thawing, and when monoclonal antibodies were kept in frequently or infrequently opened containers. Plasma (n = 4) and serum (n = 4) samples were collected from two open cows and two pregnant cows 28 days after artificial insemination. Pregnancy status was determined via transrectal ultrasonography. Plasma and serum samples were evenly separated and either centrifuged on the day of collection, or placed at 4°C and centrifuged the next day. An in-house PAG ELISA was performed on all samples before freezing (NOTHAW), after being frozen for one week (INTACT), after one freeze/thaw cycle (THAW1), two freeze/thaw cycles (THAW2), and three freeze/thaw cycles (THAW3). Data were analyzed using one-way ANOVA (GLM procedure, SAS 9.4). All samples from open cows were below the baseline of the assay. For pregnant cows, plasma samples had greater PAG concentrations than serum samples (11.84 vs 3.30 ± 0.66 ng/mL, respectively, P < 0.05). No differences were observed for day of centrifugation in both plasma and serum samples (P = 0.50 and P = 0.60, respectively) and in handling of monoclonal antibodies (P = 0.90). Freezing and thawing did not impact PAG concentrations in plasma samples (P = 0.19), but did alter serum concentrations (P = 0.01). Specifically, THAW1 (1.98 ng/mL) and THAW2 (1.42 ng/mL) serum PAG concentrations were lower compared to NOTHAW, THAW3, and INTACT samples (4.66, 4.85, and 3.57 ng/mL, respectively). Based on these data, plasma yields more consistent results than serum, even after several freeze-thaw cycles, and handling of monoclonal antibodies or time of centrifugation has no significant effect on measured PAG.

scholarly journals Freeze-Thaw Splitting Strength Analysis of PAC Based on the Gray-Markov Model

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Baoyang Yu ◽  
Zongguang Sun ◽  
Lin Qi
Keyword(s):  
Markov Model ◽  
Strength Analysis ◽  
Rapid Decline ◽  
Water Stability ◽  
Freezing And Thawing ◽  
Sem Images ◽  
Freeze Thaw ◽  
Split Ratio ◽  
Repeated Freezing ◽  
Markov Method

In this study, a freeze-thaw split test was carried out to simulate the frost-heaving behavior of permeable asphalt concrete (PAC). Furthermore, the water stability problems caused by spalling and loosening were studied. Through a comparative analysis of the freeze-thaw split ratio of porosities of 19%, 21%, and 24%, the PAC porosity with excellent water stability was determined to be 19–21%. Scanning electron microscopy (SEM) images of PAC with the three porosity values after repeated freezing and thawing verified that the porosities were greater than 24% and the asphalt film peeling area was the largest, resulting in the rapid decline of the PAC freeze-thaw split ratio. The Gray-Markov model was used to predict the water stability of the mixture with a porosity of 21%. Based on the results, a Gray-Markov method for evaluating the PAC water stability in seasonally frozen areas was introduced.

scholarly journals Experimental Investigation of the Variation of Concrete Pores under the Action of Freeze-Thaw Cycles by Using X-Ray CT

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Jie Yuan ◽  
Yang Liu ◽  
Hongxia Li ◽  
Baokun Zhang
Keyword(s):  
Experimental Investigation ◽  
Image Analysis ◽  
Failure Process ◽  
Statistical Characteristics ◽  
Freezing And Thawing ◽  
X Ray ◽  
Freeze Thaw ◽  
Complete Disintegration ◽  
Repeated Freezing ◽  
Extent Of Damage

The variation of concrete pores under the action of freeze-thaw cycles was investigated experimentally by using the X-ray CT. Firstly, the statistical characteristics of pores of concrete specimens were obtained by using the X-ray image analysis. Secondly, the variation of porosity and pore volume of concrete pores were analyzed and discussed by comparing with above characteristics. Thirdly, the failure process of the concrete specimens acted by the freeze-thaw cycles was investigated by scanning the interior of concrete specimens. The results showed that the pore volumes of concrete pores whose volumes were located at the interval [0.5 mm3, 20 mm3] have no big variation in both the amounts and volume of concrete pores, while others were found to have huge change during the process of experiment. The extent of damage acted by the repeated freezing and thawing gradually ranged from surface to complete disintegration of the interior of concrete specimens after 30 cycles of freeze-thaw acting.

Static Properties of Silty Soil Subjected to Repeated Freezing and Thawing

2013 ◽  
Vol 639-640 ◽  
pp. 925-929
Author(s):  
Han Yan ◽  
Jian Kun Liu ◽  
Tian Liang Wang
Keyword(s):  
Water Content ◽  
Ductile Failure ◽  
Friction Angle ◽  
Confining Pressure ◽  
Static Properties ◽  
Freezing And Thawing ◽  
Coefficient Of Consolidation ◽  
Freeze Thaw ◽  
Silty Soil ◽  
Repeated Freezing

In order to deeply comprehend the static properties of silty soil subjected to repeated freezing and thawing in deep seasonal frozen area, the static properties were studied on silty soil under different freeze-thaw cycles, coefficient of consolidation, water content and confining pressure. The results showed that stress-strain relationship of silty soil was work-hardening, and mainly in a ductile failure state. Correlation analysis results showed that there were good relationships between static properties, such as static modulus and static strength, and freeze-thaw cycles, coefficient of consolidation, water content and confining pressure. The cohesion decreased with in creasing of the number of freeze-thaw cycles, but there was no changing law for the internal friction angle.

Evaluation of Sample Handling in Relation to Levels of Tissue Inhibitor of Metalloproteinases-1 Measured in Blood by Immunoassay

2003 ◽  
Vol 18 (3) ◽  
pp. 170-176 ◽  
Author(s):  
M.N. Holten-Andersen ◽  
A.-S. Schrohl ◽  
N. Brünner ◽  
H.J. Nielsen ◽  
C.K. Høgdall ◽  
...  
Keyword(s):  
Plasma Samples ◽  
Tissue Inhibitor Of Metalloproteinases ◽  
Freezing And Thawing ◽  
Blood Samples ◽  
Sample Handling ◽  
Freeze Thaw ◽  
Archival Material ◽  
Repeated Freezing ◽  
Edta Plasma ◽  
Preanalytical Conditions

Background The possible effect of preanalytical conditions such as blood sample preparation and handling on TIMP-1 levels in blood needs thorough investigation. Materials and Methods Blood was collected in dry tubes and tubes containing EDTA and kept at 4°C or 20°C for 1, 3, 8, 24 or 72 hours before processing into serum or EDTA plasma. In addition, serum and EDTA plasma samples were frozen and thawed 1–8 times. TIMP-1 was measured by ELISA. Results Time to processing for up to 72 hours did not significantly affect TIMP-1 levels in serum. In EDTA plasma, TIMP-1 levels were stable for up to eight hours; however, if samples were kept for 24 hours or longer the TIMP-1 levels increased (p<0.0001). Repeated freezing and thawing had a significant effect on TIMP-1 levels in serum (p=0.04). In plasma, repeated freezing and thawing for up to six times did not influence TIMP-1. However, in plasma samples exposed to seven or eight freeze/thaw cycles TIMP-1 levels decreased, although not significantly (p=0.23). Conclusions Handling and processing of blood samples is crucial for TIMP-1 measurement by immunoassay. In serum, TIMP-1 levels are unaffected by time to processing. Plasma samples should be processed within eight hours to avoid a TIMP-1 increase. For the measurement of TIMP-1 in archival material, serum should not be used because TIMP-1 levels are significantly affected by repeated freezing and thawing; archival plasma can readily be used provided that samples have not been frozen and thawed more than six times.

scholarly journals The Effect of Repeated Freeze-thaw Cycles on the Biomechanical Properties of Canine Cortical Bone

2000 ◽  
Vol 13 (02) ◽  
pp. 59-64 ◽  
Author(s):  
C. P. Boutros ◽  
M. Kasra ◽  
M. D. Grynpas ◽  
D. R. Trout
Keyword(s):  
Cortical Bone ◽  
Biomechanical Properties ◽  
Freezing And Thawing ◽  
Destructive Testing ◽  
Torsional Strain ◽  
Three Point Bending ◽  
Freeze Thaw ◽  
Repeated Freezing ◽  
Non Destructive ◽  
Time Of Collection

SummaryAs orthopaedic investigations have become more intricate, bone specimens have sometimes undergone multiple freeze-thaw cycles prior to biomechanical testing. The purpose of this study was to determine if repeated freezing and thawing affected the mechanical properties of canine cortical bone. Six pairs of third-metacarpal bones were tested in three-point bending and six pairs of femurs were tested in torsion. At the time of collection, one member of each pair was tested destructively. The other member was tested nondestructively at the time of collection and after each of five freeze-thaw cycles, followed by destructive testing after the fifth cycle. For destructive tests, the material properties (modulus, maximum stress, maximum strain and absorbed energy) of a specimen at the time of collection were compared to those of the corresponding contralateral specimen that had undergone five freeze-thaw cycles. For repeated nondestructive tests, the modulus of a specimen at the time of collection was compared to modulus of the same specimen at each of the five thaw intervals. During destructive testing, there was a significant (p = 0.02) decrease (20%) in maximum torsional strain. Other changes in bending and torsional destructive properties were not statistically significant. During repeated nondestructive testing, there were solitary significant (p < 0.05) increases (8% and 9%, respectively) in both bending and torsional modulus. However, these isolated changes were not correlated to the number of freeze-thaw cycles. The pattern of alterations in destructive and non-destructive biomechanical properties was most consistent with varying specimen dehydration at each thaw interval. Despite using accepted methods to maintain specimen hydration, repeated freezing, thawing, handling and testing of cortical bone increased the risk of moisture loss. Unless stringent efforts are made to ensure proper hydration, the mechanical properties of canine cortical bone will be altered by repeated freezing and thawing, affecting the results of studies utilizing this technique.The effect of five freeze-thaw cycles on paired canine cortical bone specimens was evaluated using destructive and repeated non-destructive three-point bending and torsion tests. A significant decrease in destructive torsional strain and isolated significant increases in nondestructive bending and torsional modulus were most consistent with varying specimen dehydration at each thaw interval.

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