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The preparation of poly(vinyl alcohol) (PVA) hydrogels was succeeded via the freeze-thawing (F/T) method by varying the synthesis parameter conditions. The swelling capacity and long-term stability of the hydrogels were determined as a function of time at pH 2.1, 5.5 and 7.4 and found to be mainly affected by the synthesis parameter conditions. These studies showed that the swelling ratio generally increased with a low number of F/T cycles (2 and 3), high freezing temperature (- 5 and - 16 degrees C) and freeze-dried of drying type for all three pH mediums. The dried hydrogels at room temperature were found to be more stable hydrogels. In addition, the drug release studies of salicylic acid as a drug model were investigated at pH 7.4 and displayed controlled release for 120 h. The release kinetic studies obtained from drug release data demonstrated that the PVA hydrogel fits well into the Higuchi model. The release mechanism of PVA hydrogel was also determined as super case II type. WOS:000702600200001 2-s2.0-85116300994

In order to research the compressive strength and freeze-thaw durability of recycled aggregate concrete (RAC) under the combined actions of high temperature and freeze thawing recycle, a total of 2...

Reliable transportation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) patient samples from a swabbing station to a diagnostics facility is essential for the generation of accurate results. Therefore, cooling or freezing the samples is recommended in case of longer transportation times. In this study, the impact on SARS-CoV-2 detectability by reverse transcriptase PCR was assessed after prolonged unfrozen storage or repetitive freeze-thawing of SARS-CoV-2 samples. SARS-CoV-2–positive patient swabs stored in viral transport medium were exposed to different temperatures (4°C, 25°C, and 35°C) and to repetitive freeze-thawing, to assess the effect of storage conditions on reverse transcriptase PCR detection. SARS-CoV-2 RNA was still reliably detected by reverse transcriptase PCR after 21 days of storage in viral transport medium, even when the samples had been stored at 35°C. The change of Ct value per day was 0.023 to 0.046 (±0.018 to 0.019). In addition, viral RNA was still detected after 15 freeze-thaw cycles, with a change of Ct value of 0.106 to 0.197 (±0.009 to 0.061) per freeze-thaw cycle. However, compared with storage at 4°C, RNA was significantly less detectable when stored at 25°C or 35°C, or after repeated freeze-thawing. The results of this study indicate that viral RNA levels, as measured by reverse transcriptase PCR assays, are significantly, but not substantially, altered by prolonged unrefrigerated storage of up to 21 days at temperatures ranging up to 35°C or after repeated freeze-thaw cycles.

The aim of this study was to produce a high yield of direct hydrolysis of glucose from a cotton towel and wheat straw by microwave-assisted (MW) treatment. To this effect, a freeze-thawing with 3% NaOH was added before MW treatment. Multiple MW parameters were tested. For the towel, the highest glucose yield of 42.4% based on freeze-thawing with 3% NaOH-treated sample was observed after MW treatment at 200 °C for 30 s with 2% sulfuric acid as a catalyst. This corresponded to a 44.4% yield based on the cellulose content of treated samples, which was 1.3-fold higher than that of samples treated only by MW at 200 °C for 7 min with 1% sulfuric acid as a catalyst (maximum glucose yield in our previous report). For wheat straw, the highest glucose yield of 27.0% based on freeze-thawing with 3% NaOH-treated sample, and 41.9% based on the treated sample cellulose content were observed after MW treatment at 200 °C for 3 min with 0.5% sulfuric acid as a catalyst. Under the optimum conditions, the glucose yield was 40.5% from raw towel and 14.7% from wheat straw. Combined severity parameter analysis revealed that the addition of freeze-thawing with NaOH before the MW treatment increased the glucose yield and reduced the severity of the treatment conditions. In conclusion, freeze-thawing using 3% NaOH before MW treatment is effective for the direct hydrolysis of glucose from towels and wheat straw.

The aim of this study was to evaluate the effect of hydrated carbon 60 fullerene (C(60)HyFn) on ram semen quality during cryopreservation. Three ejaculates from each of seven Akkaraman rams were collected using an artificial vagina during the nonbreeding season and pooled. Pooled semen samples were divided into 10 equal parts and diluted with tris + egg yolk extender not containing (control) and containing 100, 200, 400, and 800 nM and 1, 5, 10, 20, and 40 mu M C(60)HyFn at 37 degrees C. After addition of 5% glycerol and an equilibration process for 3 hours, the samples were frozen in 0.25-mL straws in an automatic freezing device at -140 degrees C and stored in a liquid nitrogen container. Straws were thawed 24 hours after freezing and analyzed immediately with no incubation period. Motility, kinematic parameters, abnormality, vitality, hypo-osmotic swelling test (HOST), and oxidative stress levels were analyzed in thawed semen. Compared with the control, 200, 400, and 800 nM and 1 and 5 mu M C(60)HyFn doses increased motility and HOST values and decreased the dead sperm rate. When compared with the control, addition of C(60)HyFn significantly decreased malondialdehyde levels (between 200 nM and 40 mu M doses) and significantly increased glutathione peroxidase (between 800 nM and 40 mu M doses) and catalase (between 1 and 40 mu M doses) activities. In conclusion, results of this study show that the C(60)HyFn nanoparticles are nontoxic to ram semen and their supplementation in the extender is beneficial to sperm motility and membrane integrity after freeze-thawing.

This research was investigated to enhance the efficiency of enzymatic hydrolysis on wheat straw via freeze-thawing pretreatment, and to find the physicochemical structural changes after this pretreatment. Results show that, this pretreatment enhances the enzymatic hydrolysis efficiency of cellulose and hemicellulose, and hemicellulose is more susceptible to this pretreatment. The highest enzymatic hydrolysis efficiency of cellulose and hemicellulose was 57.06% and 70.66% occurred on -80℃, 24 h and -10℃, 24 h pretreated samples, with an improvement of 2.23 and 3.13 folds of control. SEM images exhibited that transverse cracks appeared before longitudinal cracks as pretreated conditions aggravated, and holes can be found on every sample after this pretreatment. FTIR and XRD analysis implied that freeze-thawing pretreatment had effect both on the crystalline and amorphous regions, and disrupted the hydrogen bonds among them. This study provided a physical pretreatment method to improve the efficiency of enzymatic hydrolysis on wheat straw.

To improve the pasting and gelling behaviors of waxy maize starch, an aqueous dispersion with or without xanthan gum was subjected to partial gelatinization (5 ℃ above the onset melting temperature of starch) and freeze-thawing treatment. After the treatments, starch granules were slightly deformed, with partial loss of birefringence, and tended to aggregate. The relative crystallinity and thermal stability of waxy maize starch crystals decreased by the treatments. These changes indicated that the treatment affected the inner structure and chain arrangement of the granules. The treated waxy maize starches, however, showed a higher overall pasting viscosity with shorter and more cohesive pastes than that of the native starch. The treated starches formed rigid gels with increased stability against freeze-thawing. The addition of small amounts of xanthan gum enhanced the effects of the treatments.

This work presents a study on the fracturing behaviour of a quartz tempered clay-based ceramic subjected to damage in freeze-thaw cycles. X-ray micro-computed tomography (micro-CT) provided high-resolution imaging of the ceramic before and during the freeze-thaw treatment, allowing to analyse a fully water-saturated sample using a special thermal stage designed to keep the sample frozen during analyses. Micro-CT 3D renderings showed the internal features of the specimen (i.e., quartz grain distribution), the increment of fracture count and size, and the detachment of ceramic and/or temper fragments from the edges of the sample over the cycles. Selected 2D micrographs, before and after freeze-thawing treatment, were analysed using the MATLAB toolbox FracPaQ. This software provided detailed data on fracture length, intensity, density, orientation and connectivity, and enabled to interpret the process of fracture initiation and propagation inside the material. These results showed that the temper plays a crucial role in ceramic fracturing behaviour under freeze- thawing conditions, as damage propagation is influenced by quartz grain distribution and orientation within the material. The study described in this work, not only offers new insights into the fracture dynamics of freeze-thawed clay-based ceramics, but also presents a new methodological approach to quantitatively measure fracture damage in porous materials.

A simple fluorescence-based cell-free DNA (CFD) assay has been previously developed that can directly measure nucleic acids without prior DNA extraction and amplification. However, studies on fluorescence-based CFD are lacking. In particular, there is no known information regarding the stability with regard to pre-analytical storage conditions in relation to time and temperature, or on the influence of freeze-thawing. Plasma was directly assayed to measure CFD using PicoGreen™ reagent. Standard linearity and accuracy were confirmed using salmon sperm DNA. Whole blood was left at room temperature (RT) and at 4˚C, and then plasma was separated. The CFD was also measured using thawed plasma after 1 week of freezing. As a correlation with a sperm DNA concentration, CFD demonstrated linearity over a wide range of concentrations, with a 0.998 correlation coefficient. The CFD level showed a change of up to 2.5 µg/ml according to pre-analytical storage time, and the changes were not consistent over time. The CFD values at RT after 1 h were similar to the baseline values, and the relative standard deviation was lowest under this condition. The CFD values between 4˚C and RT were similar over all time periods assessed. After freeze-thawing, the change in CFD value was reduced compared to that before freezing. The present study showed that CFD measurements using plasma processed within 1 h were optimal. Additionally, the effects of substantial changes according to storage conditions were reduced after freeze-thawing, and thus studies using stored samples is viable and relevant.

The objective of this study was to optimize fabrication variables that affected desirable properties of dressings. Boesenbergia rotunda extract incorporated PVA hydrogels for wound dressings were fabricated by freeze-thaw method. The fabrication variables including PVA concentration (15, 17.5 and 20 % w/w), freeze-thaw cycle (2, 3 and 4 cycles) and extract loading (30, 40 and 50 % w/w) were studied and optimized. Effects of variables on the hydrogel wound dressing properties were determined by using Box-Behnken design and response surface method. Hydrogel properties such as tensile strength, elongation at break, Young’s Modulus, water content, swelling and erosion were measured and used as the designed responses. From statistical data analysis (p , the polynomial quadratic equation which indicated the significant effects of fabrication variables on the hydrogel properties was generated. In conclusion, desirable B. rotunda extract loaded PVA hydrogel dressing was favorably designed. The optimized PVA concentration, freeze-thaw cycle and extract loading were 17.07 % w/w, 3.86 cycles and 50 % w/w, respectively.

Clinical metabolomics has utility as a screen for inborn errors of metabolism (IEM) and variant classification in patients with rare disease. It is important to understand and characterize preanalytical factors that influence assay performance during patient sample testing. To evaluate the impact of extended thawing of human EDTA plasma samples on ice prior to extraction as well as repeated freeze–thaw cycling of samples to identify compounds that are unstable prior to metabolomic analysis. Twenty-four (24) donor EDTA plasma samples were collected and immediately frozen at − 80 °C. Twelve samples were thawed on ice and extracted for analysis at time 0, 2, 4, and 6 h. Twelve other donor samples were repeatedly thawed and frozen up to four times and analyzed at each cycle. Compound levels at each time point/freeze–thaw cycle were compared to the control samples using matched-paired t tests to identify analytes affected by each condition. We identified 1026 biochemicals across all samples. Incubation of thawed EDTA plasma samples on ice for up to 6 h resulted in

This work aimed at evaluating the potential of using natural deep eutectic systems (NADES) as cryoprotectant agents (CPAs). Several combinations between natural primary metabolites that have been identified in animals that live in extreme cold climates were prepared. All systems showed very little cytoxicity towards L929 cells at concentrations high as 1–2 M. Moreover, this cell line was highly tolerant to 10% (w/v) of NADES when compared to Me2SO. To test NADES as CPAs, two cell lines were used, L929 and HacaT cells. After freeze/thawing cycle, it was possible to observe that for L929 cells, NADES presented similar behaviour to Me2SO. For Hacat cell line a significant improvement on post-thawing recovery was observed. Moreover, the results presented herein showed that NADES do not need to be removed from the freezing media after thawing the cells, which is a great advantage of these materials. Additionally, we have shown that NADES can act as CPA when cells are frozen at −20 °C. In overall, the results demonstrate the high potential of NADES to be used in cryobiology as alternative CPAs.

In vitro toxicological experiments were performed on an endothelial cell line exposed to different doses of spherical nanoparticles of cadmium and/or of lead sulfides with mean diameter 37 ± 5 nm and 24 ± 4 nm, respectively. Toxic effects were estimated by Luminescent Cell Viability Assay, endothelin-1 concentration and cell size determination. Some dose-response relationships were typically monotonic (well approximated with hyperbolic function) while others were bi- or even 3-phasic and could be described within the expanded hormesis paradigm. The combined toxicity type variated depending on the effect it was assessed by. © The Author(s) 2021.

*Dursun, Şükrü ( Aksaray, Yazar ), This study aimed to evaluate the comparative effects of taxifolin hydrate and trehalose on the quality of frozen-thawed ram spermatozoa for the first time. Ejaculates collected from six mature rams were pooled, and divided to eight equal aliquots to extend them with different concentrations of glycerol (%5 and %3), taxifolin hydrate (10, 100, and 500 μM), and trehalose (60 mM) as eight groups (G5T0, G5T10, G5T100, G5T500, G3T0, G3T10, G3T100, and G3T500). After freeze-thawing process of cryopreservation, microscopic and oxidative stress parameters, and gene expression levels were investigated for understanding of possible impacts of taxifolin hydrate and trehalose. The study showed that G3T10 resulted in the highest post-thawed viability and mitochondrial activity. Moreover, all extenders with taxifolin hydrate reduced DNA fragmentation in comparison to G5T0, but DNA damage was prevented at the highest rate in presence of G5T10. The level of LPO significantly decreased in the groups G5T500 and G3T100, and the expression levels of NQO1, GCLC, and GSTP1 genes significantly increased in the groups G5T100, G5T500, G3T10, and G3T100 compared to the group G5T0. Finally, co-supplementation of tris-based extender having 3% glycerol with 60 mM trehalose and 10 μM taxifolin hydrate in cryopreservation extender may be recommended to improve the quality of post-thawed ram spermatozoa. However, further in vivo and in vitro studies are suggested to evaluate fertility rates of frozen-thawed ram spermatozoa co-supplemented with trehalose and taxifolin hydrate.

Proteins are unstable molecules that may be severely injured by stresses encountered during freeze-thawing. Despite this, the selection of freeze-thaw conditions is currently empirical, and this results in reduced process control. Here we propose a mathematical model that takes into account the leading causes of protein instability during freeze-thawing, i.e. cold denaturation and surface-induced unfolding, and may guide the selection of optimal operating conditions. It is observed that a high cooling rate is beneficial for molecules that are extremely sensitive to cold denaturation, while the opposite is true when ice-induced unfolding is dominant. In all cases, a fast thawing rate is observed to be beneficial. The simulation outputs are confirmed by experimental data for myoglobin and lactate dehydrogenase, suggesting that the proposed modeling approach can reproduce the main features of protein behavior during freeze-thawing. This approach can therefore guide the selection of optimal conditions for protein-based formulations that are stored in a frozen or freeze-dried state.

The purpose of this study is to evaluate the rock in the extreme regions by conducting a field study and laboratory tests on three rocks of diorite, andesite, grano-diorite around Sejong Station in Antarctica. The King George Island, the research area, is mostly covered by glaciers and partially exposed bedrock along the coast. Around the coastal area and Sejong-bong, andesites, diorites, grano-diorites are distributed and were measured rebound values using Silver Schmidt hammer. This hammer, unlike conventional Schmidt value’s R, calculates Q values using input and output energy. As a result of field study, the average Q value of diorite was estimated 76, which is high compared others, and andesite was estimated 67, which is low compared others, grano-diorite was estimated 72, which is widely scattered. Freeze-Thawing test was performed based on ASTM C-666, KS F 2456. The temperature range of freeze-thawing test is from -20 ℃ to 20 ℃ referred to the published papers, and all rocks are completely saturated without humidity. The temperature holding time was set to 2 hours for temperature inside rock to -20 ℃ when the atmosphere temperature is -20 ℃. The freeze-thawing test was carried out every 20 cycles for porosity, absorption, and slaking durability. The laboratory tests were performed 200 times in total. As a result, up to 100 cycles, the porosity and absorption were not significantly different. Since then, they increased slightly. However, the slaking tended to increase gradually from the 0 cycle. In order to accurately assess the weathering of the three rocks, continuous freeze-thawing tests should be conducted. Acknowledgement : This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MIST (2019R1F1A1048854)

Highlights • Ultrasound freeze-thawing pretreatments improved the vacuum freeze-drying. • Pretreatment reduced the drying time and energy consumption. • Pretreatment changed the microstructure to various extent. • Ultrasound pretreatment retained most of the quality characteristics. • Pretreatment had no effect on the function groups and structure of pectin., Vacuum freeze-drying is a new and high technology on agricultural product dehydrating dry, but it faces the high cost problem caused by high energy consumption. This study investigated the effect of ultrasound (US), freeze-thawing (including the freeze-air thawing (AT), freeze-water thawing (WT), freeze-ultrasound thawing (UST), and freeze-air ultrasound thawing (AT + US)) pretreatments on the vacuum freeze-drying efficiency and the quality of dried okra. The results indicated that the application of ultrasound and different freeze-thawing pretreatments reduced the drying time by 25.0%–62.50% and the total energy consumption was 24.28%–62.35% less. The AT pretreatment reduced the time by of okra slices by 62.50% and the total energy consumption was 62.35% less. The significant decrease in drying time was due to a change in the microstructure caused by pretreatment. Besides, the okra pretreated with the US retained most of the quality characteristics (flavor, color, hardness, and frangibility) among all methods, while, AT + US had the most changeable characteristics in quality, which is deprecated in our study. The okra pretreated with the US and AT, separately, had the best dry matter content loss (9.008%, 5.602%), lower chlorophyll degradation (5.05%, 5.44% less), and higher contents of total phenolics, total flavonoids, and pectin, with strong antioxidant capacity, compared to other methods. The pretreatments did not have a large effect on the functional groups and the structure of pectin, but slightly affected the viscosity. It can be concluded that AT and US pretreatment methods are better than others.

The association of muscle fiber characteristics (MFC) with freeze-thawed meat quality was investigated using four different cuts (loin, M. longissimus thoracis; tenderloin, M. psoas major; top round, M. semimembranosus; eye of round, M. semitendinosus) obtained from beef carcasses (n = 10; Hanwoo steer; 28 months of age). Tenderloin had higher (P .05) composition of muscle fiber type I than the others. Its quality traits except cooking loss were not affected by freeze-thawing (P .05). However, top round having lower type I and higher type IIX compositions showed lower water-holding capacity and larger discoloration (P .01) than other beef cuts after freeze-thawing. Increased tenderness after freeze-thawing was observed only for loin (P .01) which had relatively larger size of type I fibers. In conclusion, individual muscle has different susceptibilities to freezing due to their different MFC. Considering different MFC by meat type when freezing meat will help to prevent excessive deterioration of meat quality.

*Dursun, Şükrü ( Aksaray, Yazar ), Cryoprotectants are known to have protective effects against cryodamage to spermatozoa. In this study, the cryoprotective effects of two cryoprotectants (glycerol, ethylene glycol) and cryoprotectants/trehalose combinations on frozen-thawed ram spermatozoa were investigated at the ultrastructural level. For this purpose, ejaculates collected from Konya Merino rams were pooled and diluted with a tris-based extender containing additives, including 5% glycerol, 3% glycerol +60 mM trehalose, 1.5% glycerol +100 mM trehalose, 5% ethylene glycol, 3% ethylene glycol +60 mM trehalose, and 1.5% ethylene glycol +100 mM trehalose. They were all cooled to 5°C and then frozen in 0.25 mL French straws in liquid nitrogen. The samples were thawed at 37°C and centrifuged to remove the diluents. Then, they were processed using a scanning transmission electron microscope. In the statistical analysis, the number of ultrastructurally cryodamaged and intact spermatozoa were counted in longitudinal and transverse ultrathin sections in all groups by electron microscopic examination. The amount of intact spermatozoa in the groups containing 5% ethylene glycol and 1.5% ethylene glycol +100 mM trehalose was found to be higher than other groups (p < 0.05). As a result, it was suggested that the groups of 5% ethylene glycol and 1.5% ethylene glycol +100 mM trehalose provided the highest protection for the ultrastructural morphology of frozen-thawed Konya Merino ram spermatozoa among the groups.

Poly(vinyl alcohol) – sodium alginate hydrogel dressing has been made by the control its fillers as well as for sodium alginate and polyvinyl alcohol in their compositions. It well done by means of freeze-thawing and gamma irradiation techniques throughout in their preparations. Its cross-linker parameters seemed by presences of the atomic bonding of C – O – H at 1090.79 cm−1, C=C bonding at 1611.59 cm−1 and C – H bonding at 1329.01 cm−1. Moreover, elongation at break, tensile strength, evaporation rate and swelling ratio of the hydrogel dressing proporsionally increase when each fillers enhanced both of them in their compositions. In the other words, both of them of fillers has been take effects to enhance their mechanical or physical properties of poly(vinyl alcohol) – sodium alginate hydrogel dressing.

Dursun, Şükrü ( Aksaray, Yazar ), The objective of this study was to compare the effects of different concentrations of two different cryoprotectants (glycerol, G and ethylene glycol, EG) and trehalose (T), added to the semen extender, on post-thaw ram sperm parameters. Ejaculates, collected from 6 Merino rams, were pooled and evaluated at 37 °C. The pooled samples were divided into six equal aliquots, and diluted in Tris-based extenders containing 5% G, 3% G + 60 Mm T, 1.5% G + 100 Mm T, 5% EG, 3% EG + 60 mM T, and 1.5% EG + 100 Mm T. Subsequently, the samples were cooled to 5 °C, frozen in 0.25-ml French straws, and stored in liquid nitrogen (LN2). Frozen samples were thawed individually, at 37 °C for 25 s in a water bath, for evaluation. Sperm motility was assessed using a phase-contrast microscope with a warm stage maintained at 37 °C. Acrosome integrity (FITC/PNA-PI), sperm viability (SYBR-14/PI), mitochondrial activity (JC-1/PI), DNA damage (COMET assay) and DNA fragmentation (TUNEL test) were determined. The group of samples diluted in an extender containing 5% of glycerol (Group 5% G) displayed higher percentages of subjective motility, viability and mitochondrial activity of sperm, compared to the other groups (P < 0.05). On the other hand, Group 3% G + 60 mM T yielded the second-best results for subjective motility, viability and mitochondrial activity of sperm, when compared to the other groups. The post-thaw sperm parameters of Group 3% G + 60 Mm T did not show any statistically significant difference from those of Group 5% G. There were no statistically significant differences between the groups for acrosome integrity (P > 0.05). The results of the COMET assay showed that the use of low concentrations of cryoprotectants in combination with trehalose decreased sperm DNA damage. Accordingly, Group 1.5% G + 100 mM T and Group 3% EG + 60 mM T benefited from a significantly stronger cryoprotective effect on DNA integrity, in comparison to Group 5% G (P < 0.05). According to the results of the TUNEL test, the combined use of low concentrations of cryoprotectants with trehalose decreased sperm DNA damage, when compared to the use of 5% glycerol, but this difference was statistically insignificant (P > 0.05). In conclusion, G and EG concentrations can be reduced by adding various amounts of T (60 mM, 100 mM) to the semen extender. The addition of 5% of glycerol and 3% G + 60 mM T to the semen extender did not yield statistically different post-thaw sperm parameters, when compared for protection against cryoinjury. Post-thaw sperm parameters can be improved by the supplementation of the semen extender with 3% G + 60 mM T. Thus, we recommend the use of freezing extenders containing low cryoprotectant concentrations (3% G) combined with trehalose to avoid the high level of toxic and osmotic damage caused by 5% G.

Physically crosslinked cryogels of carboxymethylated konjac glucomannan (CMKGM) with different molecular weights (Mw, 1.57 × 105–7.33 × 105 Da) and degrees of substitution (DS, 0.19–1.63) were fabricated by using the freeze-thaw technique. The acidification of CMKGM solution at a sufficiently low pH of 1.0 is a prerequisite to produce a cryogel. Both the Mw and DS of CMKGM significantly affected the formation and mechanical strength of the cryogels. A high DS value cannot ensure the formation of the cryogel when the Mw of CMKGM is not sufficiently high. While the cryogel from CMKGM with the highest Mw of 7.33 × 105 Da and lowest DS of 0.19 exhibited the highest gel strength, cryogels could not be effectively formed for CMKGM with a DS beyond 1 and Mw below 2.24 × 105 Da. Furthermore, the gel strength could be enhanced by increasing polysaccharide concentration, freezing time, and the number of freeze-thaw cycles or thawing at a moderate temperature (25 °C). It was demonstrated that the intermolecular multiple hydrogen bonding was the major driving force in the formation of CMKGM cryogels with negligible, if any, participation of crystalline ordered structures. Detailed hydrogen bonding patterns in the gel network were proposed. In acidic cryogels, there existed three types of hydrogen bonds formed by –COOH and –OH groups, whereas in neutral cryogels, two kinds of hydrogen bonding among -COO- and –OH groups were involved. The intermolecular multiple hydrogen bonding endows the physical hydrogels with excellent thermostability.

Development of medical products of new generations which are based on probiotic derivatives requires the determination of optimal conditions to preserve the biologically active potential of the active substances, i. e. metabolites and bacterial components. The effect of storage in a frozen state of structural and metabolic derivatives of Bifidobacterium bifidumon their antimicrobial activity was investigated. Structural components were obtained by cyclic freezing-thawing of the suspension of a probiotic strain of bifidobacteria, metabolic products were derived during the cultivation of bifidobacteria in their own disintegrant. The samples containing the probiotic structural and metabolic derivatives were filtered. The antimicrobial activity of the filtrates was determined by qualitative and quantitative methods immediately after isolation and storage for 60 days at (–23 ± 1)°C and compared with the test cultures of staphylococci, corynebacteria and Pseudomonas aeruginosa. The results of the study showed that low temperature storage allowed to preserve the antimicrobial potential of filtrates: there was no difference between the antimicrobial activity of fresh filtrates and the samples after storage in a frozen state if assessed with a qualitative method. The quantitative method enabled to reveal a statistically significant decrease in the antimicrobial activity of filtrates after storage in a frozen state. The difference between the quantitative indices of the viability of test cultures after exposure in fresh and frozen-thawed filtrates was 0.2–0.8 lg CFU/ml.  Probl Cryobiol Cryomed 2018; 28(3): 237–248

To explore the feasibility of utilizing recycled aggregate concrete (RAC) in revetment construction of the lower Yellow River, a series of mix proportions with local recycled aggregates (RA) were designed to evaluate its mechanical properties and durability. The morphology and micro-hardness of the interface transition zone (ITZ) were also characterized to explain the performance of RAC. Based on the compressive strength data of 13 groups of mixtures, which is larger than 30 MPa, and with the RA substitution rate not less than 50%, the RAC containing 50% recycled fine aggregate (RFA) (HDX50), 70% RFA (HDX70), and 50% recycled coarse aggregate (RCA) (HDC50) were selected. The experiment results suggest that the mechanical performance, frost resistance, and carbonation resistance of the selected RAC is generally poorer than that of natural aggregate concrete (NAC), but can meet the performance requirement of concrete for the revetment construction of the lower Yellow River. The comprehensive performance of these three mixtures ranks as: HDX50 &gt, HDX70 &gt, HDC50. When considering the RA substitution ratio as a priority, HDX70 would be the best choice and can be applied in the revetment engineering. A number of defects are observed on the surface of RA with old pastes attached. Furthermore, the ITZs formed around RA are loose and with low micro-hardness, which is deemed to be the dominating reasons leading to the weaker performance of RAC than that of NAC.

Granular starches of different origins (normal corn, waxy corn, potato and tapioca) dispersed in water (40% dry solids, w/v) were subjected to mild heating (1 h) at their onset temperatures (To) for melting (H), cooling (12 h at 4 °C) after the heat treatment (HC), and freeze-thawing (12 h at −20 °C and 1 h at 25 °C) after the heating and cooling (HCFT). Both mild heating and freeze-thawing induced the deformation of granule structure by releasing starch chains from granules, which could form outer layers on the surface of starch granules by drying the treated starches. The mild heating thus provided a stabilization effect against shear thinning during pasting. The HCFT-treated starches, especially, displayed the most significant changes in pasting viscosity with the greatest value of final viscosity. The gels prepared with the treated starches showed an enhanced rigidity with increased hardness and springiness.

This study investigates the effects of pulsed electric fields (PEF) and freeze thawing (FT) pretreatments on juice yield and quality from chicory by pressing (P). The four different modes (P, PEF- P, FT-P and P-PEF-P) were compared. The effects of pressing mode, PEF conditions, cossettes size on the juice yield, and total soluble matter (°Bx), conductivity, pH, turbidity in expressed juices were evaluated. The pressing kinetics for different modes were also investigated. For studied modes, the highest juice yield and kinetic rate were obtained for FT-P mode, the lowest was P mode. PEF-P and P-PEF-P modes resulted in the same juice yield, an increase of 9% higher than P mode. A 600 V/cm of intensity and 0.2 s duration were optimal PEF conditions with desired energy consumption. Moreover, cake mixing and relative small-sized cossettes allowed improving juice yield assisted by PEF-P mode. Quality analysis showed that expressed juice from smaller cossettes by PEF-P mode has lower turbidity and higher inulin content.

Microfibrillated cellulose (MFC) is continuously gaining attention due to its outstanding mechanical properties, in particular high strength-to-weight ratio. Recently, more and more studies target the production of porous materials, such as foams, out of this natural resource. Commonly, an energy-consuming freeze–drying method is utilized for producing pure MFC porous structures from water-based suspensions, which renders these products particularly unattractive for industry. Although alternatives for foam production have been proposed, using either modified MFC or with various additives, the freeze–drying step is still one of the most critical bottle-neck of MFC foam production upscaling. A novel straightforward freeze–thawing–drying procedure assisted by the common additive urea was herein proposed. Such method allows the production of mechanically stable, lightweight MFC structures under low-cost ambient conditions drying. The influence of the cellulose fibril characteristics, the suspension formulation and the process parameters on the final foam properties have been studied in terms of porosity, density and mechanical properties.

In order to investigate water and chloride ion transport in damaged concrete, three types of concrete were prepared, freeze-thawing (F-T) cycling and compressive loading were adopted to induce damage to concrete. Ultrasonic pulse velocity technique was used for evaluating the damage degree of concrete, and the defects of damaged concrete were also detected by X-CT. Water absorption and chloride ion penetrability were used for describing the transport properties of damaged concrete. Effects of damage degree on the water absorption rate and chloride ion penetrability were investigated in detail and the relationships were also established. The results show that the water absorption of concrete makes various responses to damage degree due to the difference of concrete type and damage method. For same concrete with similar damage degree, the water absorption rate of F-T damaged concrete is usually larger than that of concrete damaged by loading. The chloride ion penetrability of damaged concrete increases linearly with increasing damage degree, which is more sensitive to damage degree if the original penetrability of sound concrete is higher.

The aim of the present study was to evaluate different concentrations of royal jelly (RJ) supplemented extenders for post-thaw quality and incubation resilience of goat spermatozoa. Semen samples were collected from five goats. Pooled semen were diluted with soybean lecithin-based extender without RJ (control) or supplemented with different concentrations (0.25, 0.5 and 0.75%) of RJ (RJ0.25, RJ0.5, RJ0.75 respectively), at a final concentration of 150 x 106 spermatozoon/mL. Semen samples were assessed for sperm motility, plasma membrane integrity using hypoosmotic swelling test (HOST) damaged acrosome using FITC-Pisum sativum agglutinin (PSA-FITC) and DNA integrity using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). The addition of RJ (0.5%, 0.75%) led to higher percentages of subjective motilities (55.33 +/- 2.29%, 57.67 +/- 2.58%) compared to control and RJ0.25 groups (49.00 +/- 2,80%, 51.67 +/- 3.09%) (P < 0.05) following the freezethawing process. RJ0.5 and RJ0.75 groups had higher plasma membrane functional integrities (66.40 +/- 1.34%, 68.20 +/- 2.05%) and lower defected acrosome rates (24.60 +/- 3.36%, 23.80 +/- 2.27%) compared to the other groups (P < 0.05). DNA damaged spermatozoa in all groups were not significant (P > 0.05). In the end of incubation, motility and HOST rates of RJ0.5 (14.00 +/- 3.87%, 31.20 +/- 3.70%) and RJ0.75 (15.00 +/- 3.27%, 29.20 +/- 2.59%) groups were higher than control (8.00 +/- 2.54%, 18.20 +/- 3.11%) and RJ0.25 (9.00 +/- 2.07%, 20.60 +/- 2.88%) groups (P < 0.05). Also defected acrosome and DNA fragmation rates of RJ0.5 (32.20 +/- 1.30%, 5.4 +/- 0.55%) and RJ0.75 (29.20 +/- 1.30%, 5.80 +/- 0.45%) groups were significantly lower than control (38.80 +/- 0.84%, 7.40 +/- 1.34%) and RJ0.25 (39.80 +/- 2.05%, 7.00 +/- 1.58) groups. This study shows that RJ supplemented extenders have beneficial effect on goat sperm parameters at 0 h and 6 h of incubation.