Increase Of Freeze-thaw Cycles Research Articles

Seminal plasma miR-122-3p and miR-141-5p stability and its diagnosis value for idiopathic asthenospermia

To explore the stability of seminal plasma miR-122-3p and miR-141-5p and their diagnostic value for idiopathic asthenospermia. Seminal plasma miR-122-3p and miR-141-5p with various incubation time, freeze-thaw cycles and incubation time were analyzed. Real-time fluorescence quantitative polymerase chain reaction (RT-PCR) was used to detect the content of miR-122-3p and miR-141-5p, with U6 snRNA as the reference. The idiopathic asthenospermia group was further divided into grade I and II based on the progressive motility percent, and the content of miR-122-3p and miR-141-5p in the two grades were compared. No difference was detected after incubation at room temperature and 4 degrees Celsius. But seminal plasma miR-122-3p and miR-141-5p have decreased along with the increase in freeze-thaw cycles increases. RT-PCR assayed showed that the miR-122-3p content in the idiopathic asthenospermia group was significantly lower than the control group, while miR-141-5p was significantly higher. The difference in both miR-122-3p and miR-141-5p content was statistically significant (P < 0.05). A significant difference in miR-122-3p and miR-141-5p content between a and b groups was also detected (P < 0.05). The AUC-ROC of miR-122-3p was 0.88. At the cutoff value of 1.02, the sensitivity and specificity was 83% and 84%, respectively. At the cutoff of 2.95, the AUC-ROC of miR-141-5p was 0.88. The sensitivity and specificity was 84% and 70%, respectively. MiR-122-3p and miR-141-5p in seminal plasma are stable and have certain value for the diagnosis of idiopathic asthenospermia.

Immobilization of sulfate waste simulate in polymer–cement composite based on recycled expanded polystyrene foam waste: Evaluation of the final waste form under freeze–thaw treatment

A new polymer–cement composite matrix for solidification and stabilizing of low‐ and intermediate level radioactive sulfate waste, containing high concentration of sulfate as sodium salt (113.16 g/L), had been developed at the inorganic applied chemistry unit, radioisotope department, Egyptian atomic energy authority. The proposed composite is based on ordinary Portland cement and expanded polystyrene recycled from foam wastes. The integrity of the reached final waste forms (polymer–cement composite immobilizing sulfate wastes simulate) was evaluated after subjecting to freeze–thaw (FT) treatment. The cycling was performed for the final waste form at the end of 28 days curing period between (−20°C ± 1) and (60°C ± 1) for 180 days. Mass changes, compressive strength, porosity, and bulk density were determined for the solid blocks at the end of definite increasing FT cycles. To evaluate the changes in the internal structure accompanied the FT cycling, Fourier‐transform infrared, X‐ray diffraction, thermogravimetry, and scanning electron microscopy tools were used. Based on the data obtained, it could be stated that the proposed polymer–cement composite can withstand the aggressive conditions exist during the disposal process and candidate it can be used adequately for incorporating the sulfate waste concentrate originated from the boiling water reactors. POLYM. COMPOS., 38:637–645, 2017. © 2015 Society of Plastics Engineers

The effects of polymers and fly ash on unconfined compressive strength and freeze-thaw behavior of loose saturated sand

Constructions over soft and loose soils are one of the most frequent problems in many parts of the world. Cement and cement-lime mixture have been widely used for decades to improve the strength of these soils with the deep soil mixing method. In this study, to investigate the freeze-thaw effect of sand improved by polymers (i.e., styrene-acrylic-copolymer-SACP, polyvinyl acetate-PVAc and xanthan gum) and fly ash, unconfined compression tests were performed on specimens which were exposed to freeze-thaw cycles and on specimens which were not exposed to freeze-thaw cycles. The laboratory test results concluded that the unconfined compressive strength increased with the increase of polymer ratio and curing time, whereas, the changes on unconfined compressive strength with increase of freeze-thaw cycles were insignificant. The overall evaluation of results has revealed that polymers containing fly ash is a good promise and potential as a candidate for deep soil mixing application.

Assessing frost resistance of concrete by impact-echo method

This paper presents the results of an analytical and experimental programme to study the validity of measuring P-wave speed reduction by the impact-echo method as an alternative to the conventional resonance method for evaluating the frost resistance of concrete. It was found that, when subjected to freeze–thaw cycles, the relative dynamic moduli of elasticity (Ed) of concrete obtained from the two methods are in good agreement when the relative Ed is above 60%. The experimental results also show that the decrease of P-wave speed of concrete correlates well with the degradation of the relative Ed with increasing freeze–thaw cycles, implying that frequent monitoring of the in-place P-wave speed can be used to track the deterioration of real concrete structures. This potential utilisation may not be limited just to concrete structures in freezing and thawing environments, but could also be applied to those subjected to extreme environmental conditions.

Rapid Stabilization of Sands with Deep Mixing Method Using Polyester

Rapid stabilization of weak soils is one of the important and current topics in geotechnical researches such as military application and stabilization of landslides. Deep mixing is an improvement method applied in the form of creating mixed columns which involves in-situ mixing of soil and lime or Portland cement with special equipment. The aim of this study was to evaluate the feasibility of utilizing polymers as a binder for rapid stabilization of sandy soils with deep mixing method. For this purpose, a series of unconfined compression tests were conducted on three dierent sandy soils improved with polyester. In the experiments, polyester was used at three dierent ratios of 10%, 20% and 30% and samples cured for 3 hour, 1, 3, 7 and 28 days. The laboratory test results of 3 hours samples showed that soils mixed with adequate polyester could reach a similar strength range of 28 days cured soils improved with cement or lime which was reported in the literature. The unconfined compressive strength increased with the increasing polyester ratio, effective diameter, and relative density and curing period, whereas, the changes on unconfined compressive strength were insignificant with the increase of freeze-thaw cycles. The overall evaluation of results has revealed that polyester is a good promise and a potential candidate for rapid deep mixing applications.

Effect of multiple freeze–thaw cycles on the quality of chicken breast meat

The objective of this study was to determine the effects of repeated freeze–thaw cycles (0–6) on any physico-chemical changes and lipid and protein oxidation in chicken breast. The results showed that meat colour, a∗ (redness) and b∗ (yellowness) values decreased while L∗ values (lightness) increased with increasing cycle numbers. Increasing freeze–thaw cycles resulted in a greater degree of lipid and protein oxidation, as evidenced by higher contents of malondialdehyde and carbonyl compounds, and lower contents of sulfhydryl groups. Differential scanning calorimetry profiles and SDS–PAGE banding patterns of myofibrillar proteins indicated slight denaturation of myosin and actin with repeated freeze–thaw cycles. The structural changes occurring in proteins caused by oxidation directly affected the ability of muscles to retain water, as confirmed by the nuclear magnetic resonance relaxometery profile. In conclusion, multiple freeze–thaw cycles increased lipid and protein oxidation and decreased water holding capacity and colour stability of broiler chicken breast.

Influence of Freeze-Thaw Cycles on Bonded Interface Performance between CFRP and High Strength Concrete

The bonded joints between carbon fiber reinforced polymer (CFRP) and high strength concrete subjected to different freeze-thaw cycles were studied and the results were analyzed. The test results indicate that with the increase of freeze-thaw cycles, effective bond length, ultimate bond load and ultimate global slip response will decrease. But it has little effects on initial stripping load. The failure modes change from adhesive debonding to shear failure of concrete.

Effect of Freeze-Thaw on Water Stability of Aggregates in a Black Soil of Northeast China

Soil aggregate stability, an important index of the physical characteristics of a soil, can provide a good indication of a soil's erodibility, and deserves special consideration in regions with cold climate. The objective of this study was to study the effect of freeze-thaw on soil water-stable aggregates in the black soil region of Northeast China. Samples of a typical black soil in the region were collected to measure water-stable aggregates after freeze-thaw under different conditions (i.e., initial moisture contents, freeze-thaw cycles and freezing temperatures) by wet-sieving into eight particle size groups (> 10, 10–6, 6–5, 5–3, 3–2, 2–1, 1–0.5, and 0.5–0.25 mm). Freeze-thaw had the most effect on aggregate stability when the samples had an initial moisture content of 400 g kg−1. The water-stable aggregates of the four larger particle size groups (> 5, 5–3, 3–2, and 2–1 mm) reached a peak stability value, but those of the two smaller particle size groups (1–0.5 and 0.5–0.25 mm) reached a minimum value when the soil moisture content was 400 g kg−1. Water-stable aggregates of the four larger particle size groups decreased while those of the two smaller particle size groups increased with the increase of freeze-thaw cycles. As temperatures fell, the water-stable aggregates of the four larger particle size groups decreased while those of the two smaller particle size groups increased.

Tensile behavior of FRP and hybrid FRP sheets in freeze–thaw cycling environments

This study presents the results of an experimental investigation of the freeze–thaw (FT) resistance, including the hybridization of fibers, of carbon, basalt and glass fiber-reinforced polymer (CFRP, BFRP and GFRP) sheets commonly used in civil engineering practice. Coupon tests were conducted to investigate the tensile properties of FRP sheets and their corresponding epoxy resins and dry fiber sheets after up to 300 FT cycles. Sustained loading was included in the testing to reflect the behavior of FRP sheets in real structures. The test results indicate that (1) BFRP and hybrid FRP sheets have better FT resistance than CFRP and GFRP sheets, and the hybridization of fibers can contribute to the stability of the tensile properties of these materials after FT exposure; (2) the tensile properties of the resin matrix deteriorate significantly with increasing FT cycles; (3) further degradation of the tensile properties of FRP sheets is caused by sustained loading during FT cycling; and (4) the tensile behavior of dry glass fiber sheets is more sensitive to FT cycling than dry carbon and basalt fiber sheets. Lastly, the degradation mechanism of FRP sheets in FT environments is discussed.

Effect of freeze–thaw cycles on the molecular weight and size distribution of gluten

Freezing processing is widely used in food industry, but some key scientific issue is still unclear. In this paper, the effects of freeze–thaw cycles on the molecular weight, radius of gyration, free amino group content, free sulphydryl group content and molecular conformation of gluten were investigated by size-exclusion chromatography in conjunction with multi-angle laser light scattering (SEC–MALLS), spectrophotometry and atomic force microscopy (AFM). The results showed that during the freeze–thaw cycles (frozen at −18°C with cycling to 0°C for 12h and then back to −18°C per 10days) the molecular weight and radius of gyration of the gluten proteins decreased with the increase in freeze–thaw cycles, implying a depolymerisation in the high-molecular-weight fraction of the gluten. The free amino group content changed only slightly, and the free sulphydryl group content of the gluten increased from 9.8μmol/g for the control to 13.87μmol/g for the gluten stored for 120days and submitted to 12 times freeze–thaw cycling, indicating that the depolymerisation of the gluten during freeze–thaw cycling was due to the breakage of disulphide bonds. AFM images showed that the gluten chain formed a fibril-like branched network which was weakened with increasing freeze–thaw cycles storage time. Some aggregation of the gluten chains was also observed in the AFM images.

Influence of repeated freeze-thaw on dynamic modulus and damping ratio properties of silty sand

Under repeated freezing and thawing in deep seasonal frozen regions, the stability and strength of the soil are imposed in the form of large uneven settlement, instability and strength reduction, which affect the normal operation of railway lines. This study is to obtain the influencing rules of freeze-thaw on the dynamic properties(dynamic strain, confining pressure and compactness) of silty sand. Based on an amount of inner tests, the dynamic modulus and damping ratio properties of silty soil subjected to repeated freeze-thaw cycles were deeply researched and analyzed. The results are as follows: At the same dynamic strain, the relationship of dynamic stress and freeze-thaw cycles presents negative correlation, and the relationship of dynamic stress, confining pressure and compactness present positive correlation. The dynamic modulus double decreases while the damping ratio double increases with incremental increase in dynamic strain. The dynamic modulus sharply decreases while the damping ratio increases with incremental increase in freeze-thaw cycles, and then the changes level off after six freeze-thaw cycles. The dynamic modulus increases while the damping ratio decreases as the confining pressure and compactness increase at the same strain level.

Experimental Study on Frost Resistance Properties of Pumice Mixed Aggregate Concrete

Different amount of pumice were used to replace gravel to make mixed aggregate concrete, the fast freeze-thaw cycle test were conducted and the influence of pumice rate substitution to the frost resistance properties of concrete were studied.The mass loss rate, strength loss and relative dynamic elastic modulus were regarded as the evaluation index of frost resistance properties of concrete. Results showed that the mass loss rate and strength loss rate gradually decreased and the relative dynamic elastic modulus gradually increased with the increase of pumice rate, the mass loss rate, strength loss rate and the relative dynamic elastic modulus gradually decreased with the increase of freeze-thaw cycles. Polypropylene fibers could reduce the strength loss rate, improved the relative dynamic elastic modulus, but had little effect to improve the mass loss. Through the frost resistance, the frost resistance of concrete improved with the increase of pumice content, at the same time, polypropylene fiber also could improve the frost resistance of concrete.

Performance Deterioration of High Strength Concrete under Mixed Erosion and Freeze-Thaw Cycling

The mechanical properties of high strength concrete(HSC) were experimentally investigated under mixed erosion and freeze-thaw cycling according to ASTM C666(Procedure B), the erosion solution was mixed by weight of 3% sodium chloride and 5% sodium sulfate. The mass loss, relative dynamic modulus of elasticity, compressive strength, elastic modulus and other relative data were measured. The results showed that with the increasing number of freeze-thaw cycles, the surface scaled more seriously; the mass loss, compressive strength and elastic modulus continued to decrease; the relative dynamic modulus of elasticity increased slightly in the first 225 freeze-thaw cycles, then decreased in the following 75 cycles; the corresponding strain to peak stress decreased with the increase of freeze-thaw cycles. After 200 cycles, the rate of deterioration of concrete accelerated obviously.

Performance Comparison between High Strength Concrete and Ordinary Concrete under Mixed Erosion and Freeze-Thaw Cycling

: Performance of high strength concrete and ordinary concrete under alternating action of mixed erosion and freeze-thaw cycling were compared. The erosion solution was mixed by weight of 3% sodium chloride and 5% sodium sulfate. Results showed that, after 200 freeze-thaw cycles, the effect of surface scaling of ordinary concrete was more significant than that of high strength concrete, and the mass loss rate of ordinary concrete was much higher; The relative dynamic modulus of elasticity of high strength concrete slightly increased by 2.99%, while that of ordinary concrete decreased more than 13%. Compressive strength and elastic modulus of high strength and ordinary concrete behaved almost in the same way in the first 50 freeze-thaw cycles, with the increase of freeze-thaw cycles in the following test, the compressive strength and elastic modulus of ordinary concrete showed larger reductions than these of high strength concrete. As the freeze-thaw cycles increased, the corresponding strain to the peak stress of high strength concrete decreased, but it increased for ordinary concrete.

Degradation of bond between steel bar and freeze-thaw concrete after electrochemical chloride extraction

The effect of electrochemical chloride extraction (ECE) on bond strength between steel bar and freeze-thaw concrete contaminated by chloride was experimentally investigated for beam specimens with dimensions of 100 mm×100 mm×400 mm. During the experiment, 3% NaCl (vs mass of cement, mass fraction) was mixed into concrete to simulate chloride contamination, and the specimens experienced 0, 25, 50, 75 freeze-thaw cycles before ECE. In the process of ECE, different current densities and durations were adopted. It is indicated that the bond strength between reinforcement and concrete decreases with the increase of freeze-thaw cycles; the more the current and the electric quantity of ECE are, the more the loss of bond strength is; and the largest loss is up to 58.7%. So, it is important to choose proper parameters of ECE for the reinforced concrete structures contaminated by chloride and subjected to freeze-thaw cycles.

Environmental Effects on Durability of Aggregates Stabilized with Cementitious Materials

The present study focuses on investigating the effect of freeze–thaw (FT) cycles, referred to as environmental effect in this paper, on aggregates stabilized with various stabilizing agents, namely, cement kiln dust (CKD), Class C fly ash (CFA), and fluidized bed ash (FBA). Cylindrical specimens were compacted and cured for 28 days in a moist room with a constant temperature and controlled humidity. After curing, specimens were subjected to 0, 8, 16, and 30 FT cycles, and then tested for resilient modulus ( Mr ) . Results showed that Mr values of stabilized specimens decreased with increasing FT cycles up to 30. The reasons for such changes are explained by the increase in moisture content during thawing and the formation of ice lenses within the pores during freezing, causing distortion of the matrix of particles. It was also found that the decrease in Mr values varied with the type of stabilizing agents. The CKD-stabilized Meridian and Richard Spur aggregates exhibited a higher reduction in Mr values th...

The effect of metal ions on lipid oxidation, colour and physicochemical properties of cuttlefish ( Sepia pharaonis) subjected to multiple freeze–thaw cycles

The effects of different metal ions at various concentrations (0, 5, 25 ppm) on lipid oxidation, discolouration and physicochemical properties of muscle protein in cuttlefish ( Sepia pharaonis) subjected to multiple freeze–thaw cycles, were investigated. Lipid oxidation of all treatments increased as the freeze–thaw cycle increased. However, the rate of the TBARS increases varied, depending on concentration, type and valency of the metal ion. Fe(II) induced lipid oxidation most effectively and its prooxidative effect was in a concentration-dependent manner. Cu(I), Cu(II) and Cd(II) showed negligible effects on lipid oxidation. The increased lipid oxidation of cuttlefish with added iron was coincidental with the increase in b* values (yellowness), especially with increasing freeze–thaw cycles. Cu(I) and Cu(II) altered cuttlefish protein sulfhydryl content and the protein solubility decreased with a concomitant increase in the disulfide bond content. The oxidative changes of proteins were observed only when a concentration of metal ions of 25 ppm was used. Those changes were more intense with increasing freeze–thaw cycles. The Ca 2+, Mg 2+, and Mg 2+–Ca 2+–ATPase activities of cuttlefish natural actomyosin decreased markedly in the presence of copper, whereas the Mg 2+–EGTA–ATPase was increased. SDS-PAGE revealed that Cu(I) and Cu(II) induced the polymerization of muscle proteins stabilised by disulfide bond formation. However, Fe(II), Fe(III) and Cd(II) exhibited no pronounced effect on the oxidation of cuttlefish muscle proteins. Therefore, copper mainly caused the oxidation of protein, while iron induced lipid oxidation and the formation of a yellow colour in cuttlefish muscle, particularly with multiple freeze–thaw cycles.

Processing Technology Comparison of Physicochemical and Functional Properties of Cassava Starch Extracted from Fresh Root and Dry Chips

AbstractStarch was extracted from dry chips of three varieties of cassava using wet milling and dry milling methods. The physicochemical and functional properties were compared with those from fresh root. The starch obtained exhibited lower peak viscosities, breakdowns and setbacks, and higher pasting and peak temperatures than that from fresh root. Most thermal properties (onset and peak temperatures of gelatinization and retrogradation; conclusion temperatures, enthalpies and peak height indices of retrogradation; and degree of retrogradation) were found to be higher than those of fresh‐root starch. Moreover, swelling power, paste clarity and freeze‐thaw stability of the former were inferior to those of the latter. Both types of starches exhibited increased rate of syneresis with increase in freeze‐thaw cycles. Differences observed in properties of starches derived from dry chips by wet and dry millings were very minimal. No indication of major change in granule structure was noted for dry‐chip starch that would alter the properties relative to fresh root starch. Higher fiber content and annealing due to exposure to heat and moisture of the former accounted for most of the variations of properties as compared to the latter. With the advanced technology used in starch manufacturing industry today it would be possible to obtain starch from dry chips with similar quality from fresh root. This would enable the industry to overcome the cycle of glut and low season, and allow them to remain open for longer period of time in a year.

Physicochemical and enzymatic changes of cod muscle proteins subjected to different freeze-thaw cycles

The effects of freeze–thaw cycles on the physicochemical and enzymatic changes of cod muscle proteins were investigated. The activities of α-glucosidase and β-N-acetyl-glucosaminidase increased as the the number of freeze–thaw cycles increased. A loss of Ca2+-ATPase and Mg2+-Ca2+-ATPase activities was observed, while Mg2+-EGTA-ATPase activity increased, especially after one cycle of freezing–thawing, with a concomitant decrease in Ca2+ sensitivity. The surface sulphhydryl group content decreased with increasing freeze–thaw cycles, while no changes in total sulphhydryl group content were found. The surface hydrophobicity of actomyosin did not change significantly with the number of freeze–thaw cycles. The loss of protein solubility increased with increasing freeze–thaw cycles. However, no cross-linked proteins induced by formaldehyde were found. The results revealed that freeze–thaw cycles directly affected the physicochemical and enzymatic properties of cod muscle proteins. © 2000 Society of Chemical Industry