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Purpose Scale-down devices (SDD) are designed to simulate large-scale thawing of protein drug substance, but require only a fraction of the material. To evaluate the performance of a new SDD that aims to predict thawing in large-scale 2 L bottles, we characterised 3D temperature profiles and changes in concentration and density in comparison to 125 mL and 2 L bottles. Differences in diffusion between a monoclonal antibody (mAb) and histidine buffer after thawing were examined. Methods Temperature profiles at six distinct positions were recorded with type T thermocouples. Size-exclusion chromatography allowed quantification of mAb and histidine. Polysorbate 80 was quantified using a fluorescent dye assay. In addition, the solution’s density at different locations in bottles and the SDD was identified. Results The temperature profiles in the SDD and the large-scale 2 L bottle during thawing were similar. Significant concentration gradients were detected in the 2 L bottle leading to marked density gradients. The SDD slightly overestimated the dilution in the top region and the maximum concentrations at the bottom. Fast diffusion resulted in rapid equilibration of histidine. Conclusion The innovative SDD allows a realistic characterisation and helps to understand thawing processes of mAb solutions in large-scale 2 L bottles. Only a fraction of material is needed to gain insights into the thawing behaviour that is associated with several possible detrimental limitations.

Indonesian red betel (Piper crocatum) has been used traditionally to cure wounds and to prevent diseases as well as an antiseptic, while the leaves were also reported to inhibit the growth of bacteria. On the other hand, polyvinyl alcohol (PVA) is a suitable biomaterial with a wide range of applications after being transformed into hydrogels. This paper reports on the encapsulation of P. crocatum extract in PVA hydrogel synthesized by the freeze-thaw method with varying compositions and its characterizations. The internal morphology of the composite hydrogels did show some phase separation between the liquid and solid phases, while the analysis of the Fourier-transform infrared spectra confirmed that the P. crocatum extract was successfully encapsulated in the hydrogels. The hydrogels were amorphous due to the scattering of the liquid trapped within the pores. The extract was stable within the range of the room to body temperature since no significant mass decomposition of the extract was observed. The compressive modulus and the fracture stress of the composite hydrogel decreased as the fraction of extract increased due to the unfrozen ethanol fraction during the freeze-thaw process. The composite hydrogels loaded by P. crocatum extract possessed antibacterial activity against Staphylococcus aureus (gram-positive) and Pseudomonas aeruginosa (gram-negative). The release of extract from the hydrogels was immediate release following the pseudo-fickian diffusion for most of the composite hydrogels. This report thus suggests that the composite hydrogels are potential antibacterial products and can be applied for a biomedical device that requires antibacterial activity.

This research aims to evaluate the influences of the freeze–thaw (F-T) effect on the energy dissipation mechanism and damage evolution characteristics of muddy siltstones containing initial damage. At first, four initial damage levels were achieved by applying different impact loads to the intact rock, and the damage stresses for levels I, II, III, and IV initial damage were 9.80 Mpa, 17.00 Mpa, 23.34 Mpa, and 32.54 Mpa, respectively. Then dynamic compression tests were conducted on the muddy siltstones containing initial damage after 0, 5, 10, 15, 20, 25, 30, and 40 F-T cycles in the temperature range from −20 to 20 °C. The damage variable of the muddy siltstones was determined by studying energy distribution during fracture of the rock. The damage evolution characteristics of the muddy siltstone containing initial damage under the F-T effect were explored combined with the fractal theory. Test results show that (1) the dynamic compressive strength of the muddy siltstones decreases exponentially with the increasing number of F-T cycles; the dynamic compressive strength of muddy siltstone with different initial damage decreased by 54.9%, 48.4%, 39.4%, 42.5%, and 44.5% after 40 freeze-thaws, respectively, compared with that of intact. (2) The absorbed energy, reflected energy, and transmitted energy of the muddy siltstones subject to different levels of initial damage exhibit step-like changes under the effect of F-T cycles and the rate of decrease in absorbed energy decreases in the late stage of F-T cycles. (3) Both the damage variable and the fractal dimension of the muddy siltstones show an increasing trend with an increase in the number of F-T cycles, and it is more difficult for damage to become superimposed as the damage accumulates to that range causing fatigue (the damage variables ranged from 0.73 to 0.97) while the fractal dimension of the fracture surfaces in the rock still increases. (4) With the gradual increase in the damage variable, the energy absorption density of the rock is negatively correlated with the fractal dimension of the rock fragments.

Arboviruses are viral pathogens transmitted by blood-borne vectors that impose a great social and economic burden globally. Most clinical surveillance of arbovirus outbreaks underestimates the true prevalence as a large proportion of cases exhibit no or only mild clinical symptoms (i.e., are subclinical). Reports of urinary shedding of several arboviruses such as Dengue (DENV), yellow fever (YFV), and Zika (ZIKV) viruses suggest the possibility of utilizing wastewater surveillance to assess the prevalence of arboviral outbreaks. To determine the feasibility of wastewater surveillance, we investigated the decay of representative arboviruses (including DENV-2, DENV-3, YFV, and ZIKV) along with murine hepatitis virus (MHV) as a surrogate for human coronavirus within a wastewater matrix at 6, 25, or 37 °C using RT-qPCR. DENV-2, DENV-3, YFV, ZIKV, and MHV experienced a one log10reduction within 3.95-6.21 days at 25 °C and within 2.60-5.12 days at 37 °C, while incubation at 6 °C did not indicate substantial decay within 21 days. Our work suggests that these arboviruses or their RNA could persist sufficiently in wastewater over a range of temperatures, supporting the potential for wastewater-based surveillance of arboviral outbreaks. Ministry of Education (MOE) National Research Foundation (NRF) Singapore-MIT Alliance for Research and Technology (SMART) This research was supported by the National Research Foundation, Prime Minister’s Office, Singapore, under its Campus for Research Excellence and Technological Enterprise (CREATE) program, through Intra-CREATE Thematic Grant (Cities) Grant NRF2019-THE001-0003 to J.T. and E.J.A., the Singapore-MIT Alliance for Research and Technology (SMART) Antimicrobial Resistance Interdisciplinary Research Group (AMR IRG), and funding from the Singapore Ministry of Education and National Research Foundation through an RCE award to the Singapore Centre for Environmental Life Sciences Engineering (SCELSE).

Freezing and thawing plasma samples is known to perturb metabolite stability. However, no study has systematically tested how different freezing and thawing methods affect plasma metabolite levels. The objective of this study was to isolate the effects of freezing from thawing on mouse plasma metabolite levels, by comparing a matrix of freezing and thawing conditions through 10 freeze–thaw cycles. We tested freezing with liquid nitrogen (LN2), at −80 °C, or at −20 °C, and thawing quickly in room temperature water or slowly on ice. Plasma samples were extracted and the relative abundance of 87 metabolites was obtained via liquid chromatography–mass spectrometry (LC–MS). Observed changes in metabolite abundance by treatment group correlated with the amount of time it took for samples to freeze or thaw. Thus, snap-freezing with LN2 and quick-thawing with water led to minimal changes in metabolite levels. Conversely, samples frozen at −20 °C exhibited the most changes in metabolite levels, likely because freezing required about 4 h, versus freezing instantaneously in LN2. Overall, our results show that plasma samples subjected to up to 10 cycles of LN2 snap-freezing with room temperature water quick-thawing exhibit remarkable metabolomic stability.

The Helankou rock as the relics carrier in Ningxia, China, have been suffering from serious weathering caused by variable environmental conditions. To study the freeze-thaw damage characteristics of Helankou relics carrier rocks, three dry-wet conditions (i.e., drying, pH = 2 and pH = 7) together with freeze-thaw experiments have been carried out at 0, 10, 20, 30, and 40 cycles. Additionally, a series of triaxial compression tests have been carried out at four different cell pressures of 4 MPa, 8 MPa, 16 MPa, and 32 MPa in tandem with a non-destructive acoustic emission technique. Subsequently, the rock damage variables were identified based on elastic modulus and acoustic emission ringing counts. It has been revealed that the acoustic emission positioning points reflected that the cracks would be concentrated near the surface of main fracture at higher cell pressures. Notably, the rock samples at 0 freeze-thaw cycles failed in pure shear. However, both shear slip and extension along the tensile cracks were observed at 20 freeze-thaw cycles, while tensile-oblique shear failure occurred at 40 freeze-thaw cycles. Not surprisingly, the decreasing order of deterioration inside the rock was observed to be (drying group) > (pH = 7 group) > (pH = 2 group). The peak values of damage variables in these three groups were also found to be consistent with the deterioration trend observed under freeze-thaw cycles. Finally, the semi-empirical damage model could rigorously ascertain stress and deformation behavior of rock samples, thus providing theoretical basis to establish a protection framework for Helankou relics.

This paper presents laboratory data from tests on four fine-grained soils: reconstituted Kaolinite, destructured Bothkennar clay, reconstituted Bothkennar clay, and reconstituted Gault clay. The soil samples were conditioned in an oedometer cell while being subjected to varying numbers of freezing and thawing cycles. The influence of freeze-thaw cycles on key soil parameters, including the hydraulic conductivity, Atterberg limits, compression and swelling index was studied. The experimental results were then compared with the analysis of a previously published database of hydraulic conductivity measurements on fine-grained soils called FG/KSAT-1358. The paper demonstrates that while multiple cycles of freezing and thawing affect some of the studied soil parameters, such as the Atterberg limits and the compression characteristics, the effects on the hydraulic conductivity transformation model parameters, linking the water content ratio to hydraulic conductivity are less apparent. The results are useful for geotechnical and pavement engineers when making assessments of freeze-thaw effects on subgrade materials in cold regions.

At 10:05 a.m. on 4 February 2022, the perilous rock mass Yizhuxiang in Leizu Town, Yuan’an County, Hubei Province, China collapsed on a large scale. The Yizhuxiang collapse was about 35 m in length, 52 m in height, and 29 m in maximum thickness. The volume of the collapse was 5.32 × 104 m3. It threatened the transport of the national trunk road, destroyed the branch road and some cement mixing station workshops, and caused serious economic losses. The rock mass exposed in the collapse was dolomite with developed joint fractures. Under the effects of mining and unloading, fractures occurred in the rock mass; the top of the rock mass was bent and deformed towards the free face; and tension cracks were formed on the rear edge. The safety ore pillar directly below the collapsed body was compressed and deformed under the action of gravity, thus accelerating the internal deformation of the rock mass and leading to the formation of multiple dominant joints inside the rock mass. In the winter of 2021, the weather was extreme, with heavy snowfall and low temperatures. Under the effects of freeze–thaw, the strength of the rock mass declined and the tension cracks further expanded so that the rock mass experienced an accelerated deformation and finally collapsed. Causes of the collapse include mining activity beneath the collapsed mass and heightened extreme weather. The cause of the landslide disaster in this area is, however, freeze–thaw, which deserves the attention of scholars and the vigilance of the local government.

Objective Coagulation tests are sensitive to pre-analytical variables. The aim of our study is to identify the effect of transportation and freeze-thaw status on for Factor VIII, Factor IX, Anti-thrombin III, Protein S, Protein C, Prothrombin time (PT) and Activated partial thromboplastin time (aPTT). Materials and methods The study was performed on 102 plasma samples obtained from 34 healthy volunteers. The samples were divided into three groups. Group A was analyzed whereas group B, C were frozen at −20°C. After 24 h, group B and C were transported for 2 h. Following the transfer, group B was analyzed and C was frozen at −20°C. After 24 h, group C was analyzed. Analyses of samples were performed in Thrombolyzer-XRM for PT, aPTT, Factor VIII, Factor IX, Anti-thrombin III, Protein C and Protein S. Results There were significant variations for PT, aPTT, Protein S, Factor VIII and Factor IX for group A&B and A&C comparisons in different stability criteria approaches. In significant change limit and percentage change calculations Protein S, Factor VIII and IX showed significant differences. For acceptable change limit approach, aPTT and Factor IX showed significant changes. Conclusion Laboratories should take precautions for transportation and freeze-thaw cycles to prevent inaccurate results., Amaç Koagulasyon testleri analiz öncesi değişkenlere karşı duyarlıdır. Çalışmamızın amacı, donma-çözünme ve taşıma etkisinin Faktör VIII, Faktör IX, Anti-trombin III, Protein S, Protein C, Protrombin zamanı (PT) ve Aktive parsiyel thromboplastin zamanı (aPTT) sonuçlarına etkisini araştırmaktır. Gereç ve Yöntem Çalışma 34 sağlıklı gönüllüden elde edilen 102 plazma örneğinde gerçekleştirildi. Örnekler 3 gruba ayrıldı: Grup A örnekleri hemen analiz edilirken Grup B ve Grup C örnekleri −20°C’de donduruldu. 24 saat sonra Grup B ve Grup C örnekleri 2 saat süre boyunca taşındı. Taşınmanın ardından, Grup B örnekleri analiz edilirken Grup C örnekleri tekrar −20°C’de donduruldu. 24 saat sonra Grup C örnekleri analiz edildi. Örneklerden Thrombolyzer-XRM cihazında, PT, aPTT, Faktör VIII, Faktör IX, Anti-trombin III, Protein C ve Protein S testleri çalışıldı. Sonuçlar Farklı stabilite kriterleri yaklaşımlarına göre PT, aPTT, Protein S, Faktör VIII and Faktör IX sonuçlarında Grup A&B ve A&C karşılaştırmalarında önemli farklılıklar elde edildi. Anlamlı değişim sınırı ve yüzde değişim hesaplamalarında Protein S, Faktör VIII and Faktör IX sonuçlarında, kabul edilebilir değişim sınırı yaklaşımında ise aPTT ve Faktör IX sonuçlarında anlamlı farklılıklar bulundu. Tartışma Laboratuvarlar yanlış sonuçları önlemek için örneklerin taşınma ve donma-çözünme döngüleri için önlemler almalıdır.

This research will help to improve our understanding of the fracture properties of ECC at low temperatures (long-term low temperatures, freeze–thaw) and evaluate the safety properties of ECC under low-temperature conditions. Three levels of saturation (saturated, semi-saturated, and dry), four target temperatures (20, 0, −20, and −60 °C), and the effect of the coupled of the two on the mode I fracture properties of ECC were investigated. Then, we compared and analyzed the fracture properties of ECC loaded at 20 and −20 °C, after different freeze–thaw cycles (25, 50, 100 cycles), which were compared with saturated specimens without freeze–thaw at the four target temperatures to analyze the differences in low-temperature and freeze–thaw failure mechanisms. Temperatures and saturation have a significant effect on the fracture properties. Low temperatures and freeze–thaw treatments both decreased the nominal fracture energy of ECC. Distinct differences in matrix and fiber-matrix interface damage mechanisms have been discovered. Low temperatures treatment transforms ECC from a ductile to a brittle fracture mode. However, even after 100 freeze–thaw cycles, it remains ductile fractured. This study complements the deficiencies of ECC in low-temperature theoretical and experimental applications, and it sets the stage for a broad range of ECC applications.

Graphene can effectively improve the mechanical and electrical properties of cement-based materials due to its excellent tensile strength, thermal conductivity and electrical conductivity. In this paper, the effects of freeze–thaw on the conductivity and sensing properties of graphene-based cement materials were investigated. After the preparation of graphene-based cement materials, they were subjected to different times of freeze–thaw action. The experiments were designed to analyze the influence of freeze–thaw on the electrical conductivity, humidity sensitivity, thermosensitivity and pressure sensitivity of graphene-based cement composites. The results show that the influence of freeze–thaw on the electrical conductivity of graphene is mainly manifested in the influence on the resistivity and the extension of the polarization time, and the influence on the percolation transition zone is small. After freeze–thaw, the polarization time of the specimen decreases with the increase of the relative water content. The temperature has a great influence on the polarization effect of graphene-based cement composites and the composites with graphene content of the zone B still show satisfactory pressure-sensitive property after freeze–thaw.

To improve the high brittleness of recycled aggregate concrete containing iron ore tailings (TRAC), the feasibility of adding polypropylene fiber (PPF) to TRAC was studied by performing a compression stress–strain curve test, scanning electron microscope characterization, and a freeze–thaw cycle test. The results indicated that PPF had a beneficial impact on reducing the brittleness of TRAC. With the increase in PPF content, the peak strain increased, the elastic modulus decreased, and the peak stress and energy absorption capacity increased at first and then decreased. Furthermore, the microstructure investigation revealed that the interface friction between the PPF, aggregate, and cement matrix was the main source of energy dissipation. When the load acted on the concrete, the stress was dispersed to the fiber monofilaments, thus effectively enhancing the peak stress and peak strain of concrete and suppressing the generation and development of cracks in the concrete. In terms of freeze–thaw resistance, adding a small amount of PPF could reduce the negative effects of the freeze–thaw process on the cement matrix. On the premise of ensuring strength, the waste utilization should be as high as possible. Therefore, it was suggested that the content of PPF in fiber-reinforced tailings recycled aggregate concrete (TRAC-PP) should be 0.6%.

Keratins are highly attractive for medical applications due to their inherent self-assemblies characteristics and biocompatibility. However, nearly all researches have focused on the properties of hybrid hydrogels which was prepared from human hair keratin with other materials, and the preparation methods and properties of pure keratin hydrogels are rarely studied. Thus, we extracted keratins from rabbit hair, and a low concentration and high purity RHK hydrogel was then prepared by a simple freeze–thaw cycle and used to study gelation and the optical properties. The results indicated that RHK keratin hydrogel is a reversible thixotropic system and elastic modulus the storage modulus (G′) substantially improves with freeze–thaw cycles. The systematic assessments including microstructural observation, porosity, and the secondary structure confirmed that the structure and properties of keratin hydrogels can be changed by controlling freeze–thaw cycles. Meanwhile, it is found that RHK hydrogel had high optical transmittance, and still maintained its fluorescent properties, which would be useful to observe the wound healing and locate the drug delivery process.

Carbon dioxide (CO2) is both a primary greenhouse gas and a readily available energy source. In this study, a new underground coal permeability enhancement technique utilizing cryogenic liquid CO2 (L-CO2) cyclic injection is proposed. The key parameters that determine the feasibility of this technique are cycle period and cycle number within a fixed working period. The optimal value of these two parameters mainly depends on the pore structure evolution law of coal cores before and after cryogenic L-CO2 cyclic freeze–thaw. Accordingly, nuclear magnetic resonance (NMR) was employed to study the evolution characteristics of the fracture networks and pore structures in coal cores subjected to different freeze–thaw cyclic modes. The results demonstrated that the amplitude and width of all peaks of the T2 spectra of the three coal cores (lignite, gas coal, and 1/3 coking coal) increased with an increase in the number of injection cycles. Additionally, as the number of freeze–thaw cycles (Nc) increased, the total porosity and effective porosity of the coal cores increased linearly before stabilizing, while the residual porosity first steadily diminished and afterwards became constant. Furthermore, the variation in the total porosity and residual porosity of the coal cores continuously diminished with an increase in the level of metamorphism. The NMR permeability of the coal cores showed a similar pattern to the porosity. Accordingly, the optimal parameters for cryogenic L-CO2 cyclic injection during a complete working time were determined to be Nc = 4 and Pc = 30 min. A field test demonstrated that after L-CO2 cyclic freeze–thaw treatment, the average gas drainage concentration of a single borehole in the test region increased by 1.93 times, while the pure flow of a single gas drainage borehole increased by 2.21 times. Finally, the gas attenuation coefficient decreased from 0.036 to 0.012. We concluded that the proposed permeability enhancement technique transformed coal seams from hard-to-drain to drainable.

Three-dimensional concrete printing (3DCP) is becoming more common in the construction industry nowadays; however, the aspect of durability of printed concrete is not well-studied yet. Frost resistance is a very important factor for durability of concrete structures located in northern regions. Since air-entraining agents (AEAs) are widely used in conventional concrete, this paper focuses on exploring the potential of using AEAs in 3D concrete as well—the main objective is to determine how it affects fresh and hardened properties, including frost resistance of 3D concrete. Three different mixes were printed and cast—the dry mix consisted of ordinary Portland cement (OPC), limestone filler (LF), sand, as well as viscosity modifying agent (VMA) and superplasticizer (SP). Two mixes contained different amounts of AEA, the third one was used as reference. First, fresh state properties were tested—air content, density, and mini cone flow test. Second, 28-day compressive and flexural strength tests were carried out; bulk and particle densities were also determined. Next, both cast and printed concrete samples were subject to freeze–thaw cycles according to provisions of CEN/TS 12390-9, mass loss due to surface scaling was determined for each sample. As a result, printed concrete samples containing AEA in the amount of 0.06% of binder mass showed the highest frost resistance—addition of AEA decreased both flexural and compressive strength of this printed concrete mix by 30–40%. To conclude, the obtained results give an insight of how addition of AEA to printed concrete mix affects its properties both in long and short term. Further research of certain aspects, for instance, the air void system and pore distribution is needed to gain a deeper understanding on how to increase durability of 3D concrete.

Understanding the interactions between ground freeze-thaw, groundwater flow, and solute transport is imperative for evaluating the fate of contaminants in permafrost regions. However, predicting solute migration in permafrost-affected groundwater systems is challenging due to the inherent interactions and coupling between subsurface mass and energy transport processes. To this end, we developed a numerical model that considers coupled groundwater flow, subsurface heat transfer, and solute transport, including water-ice phase change, solute-dependent porewater freezing, and temperature-dependent solute reaction rates. As an illustrative example, we present simulations to investigate the potential for contamination from a municipal wastewater lagoon in the Canadian sub-arctic. Two-dimensional groundwater models assuming varying permafrost conditions were developed to evaluate possible contaminant migration scenarios associated with groundwater flow from the lagoon to a river, including the transport of conservative, degradable, and sorbing solutes. Model results reveal important transport mechanisms controlling the behavior of aqueous contaminants in permafrost landscapes as well as the hydrogeologic factors affecting reactive transport in cold regions. Seasonal freeze-thaw episodically restricts connectivity of transport pathways, which attenuates both transport and reaction rates. However, elevated solute concentrations can depress the freezing temperature of porewater and produce thaw-induced solute transport. Both thermally driven and solute-enhanced thaw can decrease ice content in permafrost, which can have significant implications for solute migration. Therefore, thermo-hydrogeologic process controlling reactive transport in cold-region groundwater systems must be considered when quantitatively assessing the impact of changing environmental conditions on contaminant hydrogeology.

Large quantities of organic matter are stored in frozen soils (permafrost) within the Qinghai–Tibetan Plateau (QTP). The most of QTP regions in particular have experienced significant warming and wetting over the past 50 years, and this warming trend is projected to intensify in the future. Such climate change will likely alter the soil freeze–thaw pattern in permafrost active layer and toward significant greenhouse gas nitrous oxide (N2O) release. However, the interaction effect of warming and altered soil moisture on N2O emission during freezing and thawing is unclear. Here, we used simulation experiments to test how changes in N2O flux relate to different thawing temperatures (T5–5°C, T10–10°C, and T20–20°C) and soil volumetric water contents (VWCs, W15–15%, W30–30%, and W45–45%) under 165 F–T cycles in topsoil (0–20 cm) of an alpine meadow with discontinuous permafrost in the QTP. First, in contrast to the prevailing view, soil moisture but not thawing temperature dominated the large N2O pulses during F–T events. The maximum emissions, 1,123.16–5,849.54 μg m–2 h–1, appeared in the range of soil VWC from 17% to 38%. However, the mean N2O fluxes had no significant difference between different thawing temperatures when soil was dry or waterlogged. Second, in medium soil moisture, low thawing temperature is more able to promote soil N2O emission than high temperature. For example, the peak value (5,849.54 μg m–2 h–1) and cumulative emissions (366.6 mg m–2) of W30T5 treatment were five times and two to four times higher than W30T10 and W30T20, respectively. Third, during long-term freeze–thaw cycles, the patterns of cumulative N2O emissions were related to soil moisture. treatments; on the contrary, the cumulative emissions of W45 treatments slowly increased until more than 80 cycles. Finally, long-term freeze–thaw cycles could improve nitrogen availability, prolong N2O release time, and increase N2O cumulative emission in permafrost active layer. Particularly, the high emission was concentrated in the first 27 and 48 cycles in W15 and W30, respectively. Overall, our study highlighted that large emissions of N2O in F–T events tend to occur in medium moisture soil at lower thawing temperature; the increased number of F–T cycles may enhance N2O emission and nitrogen mineralization in permafrost active layer.

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.

Dacarbazine (DTIC) is an antitumor agent that has limited clinical applications due to its insolubility, instability and toxicity to normal cells. One possibility to achieve controlled release is PVA-based NPs. This work presents electrospun NPs that combines PVA and DTIC. The results showed that DTIC NPs had mean particle sizes of 458.2 ± 113.6 nm, suggested the presence of DTIC in an amorphous state and showed a burst in vitro drug release followed by constant release. The cytotoxicity evaluation showed that DTIC NPs were effective against glioblastoma cells. This study indicates that the formulated NPs improved DTIC solubility and efficacy. yes

Lime and cement are quite compatible for stabilizing clayey soils; changes in a thermal regime may inversely affect the advantages of stabilized soil. The present study interprets changes in the mechanical behaviour of frozen and unfrozen Himalayan soil samples through an unconfined compressive strength test. The soil was treated with ground eggshell powder (3%-9%) and alkali activator (Sodium chloride) (2%-6%); it was reinforced with arbitrarily distributed polypropylene fibers (0.05%-0.15%). Standard 7, 14 and 21-day-old soil specimens were tested in unfrozen conditions, while fresh 21-day-old soil specimens were tested after 3, 5 and 10 freeze-thaw cycles. The design of the experiments was based on the Taguchi technique and arranged in an orthogonal array. The results of the research clearly show that poultry waste (eggshell powder) and alkaline soil stabilizer improved the strength behaviour of the subject soil. On the other hand, the polypropylene fibers played an important role in changing the brittle behaviour of the stabilized soil to ductile behaviour. The sudden collapse of a structure may be avoided by using polypropylene fibers.

The textural properties of a rock and the characteristics of its pore network are intrinsic variables to consider when investigating the resistance of rock to weathering. To establish the influence of these variables on the effectiveness and progression of weathering processes, two lithotypes of a limestone were analyzed with respect to their texture and porosity, and to their performance during artificial weathering experiments. The studied rock is Vicenza Stone, a bioclastic limestone with heterogeneous texture, variable grain size from fine to coarse, and high levels of open porosity (27–28%). Two sets of samples were obtained from a quarry, defining coarse-grained (CGV) and fine-grained (FGV) lithotypes of Vicenza Stone. Multiple techniques (optical microscopy, scanning electron microscopy, image analysis, mercury intrusion porosimetry, hygroscopicity, ultrasound, and water absorption) were used to characterize the texture and porosity of the limestone. The sample sets were subjected to freeze–thaw (UNI 11186:2008, Cultural heritage—Natural and artificial stone—Methodology for exposure to freeze-thawing cycles, 2008) and salt-crystallization (partial continuous immersion method with a Na2SO4-saturated saline solution) weathering experiments to investigate the processes and progression of mechanical and chemical weathering. Differences in freeze–thaw-induced micro-cracks and in the deposition of secondary micrite between the lithotypes show that the CGV has an overall higher susceptibility to freeze–thaw weathering than FGV. Salt-weathering processes induced micro-crack formation, material dissolution, and secondary precipitation, suggesting the simultaneous occurrence of mechanical stress and chemical dissolution–precipitation processes. FGV is more prone to salt-induced weathering than CGV, whereas CGV is susceptible to the wide thermal excursions of freeze–thaw weathering.

The bonding surface structure generated by the repair of concrete structures has been paid more attention as a weak point. The effects of old concrete age, interface roughness, and freeze-thawing (F-T) attack on adhesive interface are comprehensively investigated. In this study, six kinds of interface roughness and five different old concrete age are designed. The interfacial bonding property is mainly evaluated by splitting tensile strength (fts). Fractal analysis was used to characterize the interface roughness using laser scanning data. In general, the fts increased with the increasing value of interface fractal dimension. The relationship between fts and fractal dimension value was further analyzed, considering the old concrete ages and the F-T cycles. The results show that the effect of roughness on the bonding property of new-to-old concrete is more significant than the age of old concrete, and the influence of the F-T cycles on the bonding surface is mainly reflected in the initial stage of the F-T deterioration process. The relative dynamic elasticity modulus decreased obviously under F-T cycles, especially for the specimens with low interface roughness. In combination with the results of two non-destructive methods (ultrasonic non-destructive test and relative dynamic elastic modulus test), the larger roughness and the smaller age of old concrete can improve the bond performance.

Background Both RNA-Seq and sample freeze-thaw are ubiquitous. However, knowledge about the impact of freeze-thaw on downstream analyses is limited. The lack of common quality metrics that are sufficiently sensitive to freeze-thaw and RNA degradation, e.g. the RNA Integrity Score, makes such assessments challenging. Results Here we quantify the impact of repeated freeze-thaw cycles on the reliability of RNA-Seq by examining poly(A)-enriched and ribosomal RNA depleted RNA-seq from frozen leukocytes drawn from a toddler Autism cohort. To do so, we estimate the relative noise, or percentage of random counts, separating technical replicates. Using this approach we measured noise associated with RIN and freeze-thaw cycles. As expected, RIN does not fully capture sample degradation due to freeze-thaw. We further examined differential expression results and found that three freeze-thaws should extinguish the differential expression reproducibility of similar experiments. Freeze-thaw also resulted in a 3′ shift in the read coverage distribution along the gene body of poly(A)-enriched samples compared to ribosomal RNA depleted samples, suggesting that library preparation may exacerbate freeze-thaw-induced sample degradation. Conclusion The use of poly(A)-enrichment for RNA sequencing is pervasive in library preparation of frozen tissue, and thus, it is important during experimental design and data analysis to consider the impact of repeated freeze-thaw cycles on reproducibility. Graphical abstract

The present study investigated the resistance of concrete blended with ground granulated blast furnace slag (GGBS) and ferronickel slag (FNS) to cycles of freeze and thaw. The replacement ratio of the binders was 0%, 50 wt% of GGBS and 30 wt% of GGBS + 20 wt% of FNS for O100, OG50 and OG30F20, respectively. Specimens consisted of cement paste and concrete kept at 0.45 water/binder ratio. After 28 days of curing, specimens were subjected to freeze and thaw cycles (300) for measuring the variation of strength, weight loss and fundamental transverse frequency. Simultaneously mercury intrusion porosimetry was performed to examine the pore structure modifications at 28 days. The hydration products for cement paste cured at each determined age were characterized by X-ray diffraction and the content of CH and CSH was obtained from thermogravimetric analysis (TGA). As a result, the ternary blended concrete specimens showed lower deterioration degree when subjected to the freeze and thaw cycles. This may be due to a latent hydraulic and/or pozzolanic reaction producing more CSH in the matrix, which in turn increases the volume of small pores. The increased content of C–S–H gel for OG30F20 was confirmed by TGA, accounting for 69.9%. However, the binder system consisting of ordinary Portland cement and GGBS did not exhibit higher resistance to the given deleterious environment, presumably due to a delayed hydration process.

The stability of the active pharmaceutical ingredients (API) and the final product is one of the most important factors in the design and development of drug forms. The storage conditions stated on the product label arise from the evaluation of the scientific data extracted from stability studies. In this study, the effect of ointment base excipients on stability was conducted, besides the effect of freeze-thaw tests on product stability. Dexketoprofen trometamol which is a highly soluble active substance in the water was selected as a model drug within the scope of this study. It was formulated as a semi-solid dosage form with different types of bases (an oil-based, a water-based, and emulsion-based ointment excipients). The stability tests in long-term and accelerated conditions were performed on each product at certain periods. The commercial product of dexketoprofen trometamol (Dexalgin gel) was also evaluated. The loss of API in the ointment with high oil content was higher than the others in both long term and accelerated stability test conditions. The active ingredient loss was higher than 5% even after the first freeze-thaw process for all formulation including commercial product in gel form. After two cycle-freeze-thaw processes, the amount of API was dramatically changed (from 18% of degradation in even commercial gel products, which were the most stable formulation in this study). It was presented that freeze-thaw processes were much more crucial than the two-month storage in high temperatures (i.e. 40°C).

In the last decades, liposomes acquired a striking success in the biomedical field thanks to their biocompatibility and drug delivery ability. Many liposomal drug formulations have been already approved by the Food and Drug Administration (FDA) and used for the treatment of a wide range of pathologies with or without further engineering. Their clinical application requires strict compliance with high standard quality rules, and it is crucial to employ storage methods that do not affect the integrity of the vesicles and preventing the leakage of their cargo. In this work, the design of a suitable formulation for freeze-drying had been investigated for two different liposomes, DOPC-DOTAP and the PEGylated counterpart, DOPC-DOTAP-DSPE-PEG. The role of various cryoprotectants was evaluated paying attention to their ability to preserve the structural integrity of liposomes. At first, the study was focused on freezing and two methodologies were investigated, quenching in liquid nitrogen and shelf-ramped freezing. This analysis showed that the disaccharides (cellobiose, glucose, lactose, sucrose, and trehalose) and the polyol (mannitol) protected successfully the integrity of liposomes, while during the process, in the presence of a surfactant, liposomes were strongly damaged and fragmented by the ice crystals. Furthermore, the choice of the rate of freezing depended on the different compositions of the lipid bilayer. Finally, the effects of lyophilization on liposomes with and without additives were studied; cellobiose, lactose and trehalose showed encouraging results for the maintenance of the morpho-functional parameters of liposomes during the entire freeze-drying process.

Freeze-thaw cycles have significant influences on slope erosion processes. In this study, simulated rainfall laboratory experiments were implemented to investigate erosion processes and the relationship between the soil loss rate and hydraulics conditions under different thawed depths and rainfall intensities. The results indicated that linear regression could be used to describe the relationship between the soil loss rate and runoff time. Soil loss rate, as measured by the curve slope k (represented the increase rate in the soil loss rate), generally increased with runoff time over different thawed depths across all rainfall intensities. The k values generally increased with rainfall intensity from 0.6 to 1.2 mm/min, with the exception of the 4 cm thawed slope, for which the k values initially increased before decreasing with rainfall intensity from 0.6 to 1.2 mm/min. The mean soil loss rate and range also increased with thawed depth under the same rainfall intensity. Finally, the interaction of rainfall intensity and thawed depth had the greatest effect on soil loss rate, while stream erosion power was the hydraulic parameter that exhibited the best soil loss rate prediction performance. The results presented herein improve the understanding of the response of freeze-thaw/water compound erosion to hydraulic conditions.

The monitoring of the freeze/thaw dynamic of high-latitude Earth regions is of paramount importance for the study of the carbon cycle and the climate changes. Current approaches essentially rely on the use of active and passive microwave remote sensing, while limited work has been dedicated to study the potential of the Global Navigation Satellite System Reflectometry technique based on spaceborne platforms. In this contribution, reflectivity values derived from the TechDemoSat-1 data have been collected and elaborated, to be compared against the SMAP freeze/thaw product. The proposed analysis indicates a significant seasonal cycle of freeze/thaw state in the calibrated reflectivity, thus opening new perspectives for the bistatic L-band high-resolution satellite monitoring of the freeze/thaw state.

&Tau, he present study investigates the pore structure and transport properties of carbon nanotube-modified cementitious mortars after exposure to freeze-thaw cycles and immersion to sulfate ion solution (sulfate attack) and compares them to those of un-exposed mortars. The effect of parameters related to carbon nanotube content (within the range of 0.2&ndash, 0.8 wt.%) and type of dispersant (superplasticizer/surfactant) are investigated. It is found that carbon nanotube inclusion results, overall, in a significant drop of the total porosity before exposure. Results demonstrate that environmental exposure leads to a reduction of the fraction of small diameter pores and a respective increase in capillary porosity for both dispersive agents compared to un-exposed specimens. Diffusion coefficients of nano-modified specimens are lower compared to those of un-modified mortars, both before exposure and after sulfate attack. In the case of freeze-thaw cycling, the diffusion coefficients were found to be higher in carbon nanotube-modified mortars when surfactants were used as dispersants, although with improved gas permeability values.

Wintergreen fern Polystichum acrostichoides has fronds that are photosynthetically active year-round, despite diurnal and seasonal changes in soil moisture, air temperature and light availability. This species can fix much of its annual carbon during periods when the deciduous canopy is open. Yet, remaining photosynthetically active year-round requires the maintenance of photosynthetic and hydraulic systems that are vulnerable to freeze–thaw cycles. We aimed to determine the anatomical and physiological strategies P. acrostichoides uses to maintain positive carbon gain, and the coordination between the hydraulic and photosynthetic systems. We found that the first night below 0 °C led to 25 % loss of conductivity (PLC) in stipes, suggesting that winter-induced embolism occurred. Maximum photosynthetic rate and chlorophyll fluorescence declined during winter but recovered by spring, despite PLC remaining high; the remaining hydraulic capacity was sufficient to supply the leaves with water. The onset of colder temperatures coincided with the development of a necrotic hinge zone at the stipe base, allowing fronds to overwinter lying prostrate and maintain a favourable leaf temperature. Our conductivity data show that the hinge zone did not affect leaf hydraulics because of the flexibility of the vasculature. Collectively, these strategies help P. acrostichoides to survive in northeastern forests., Wintergreen ferns, such as Polystichum acrostichoides, retain their fronds throughout the year despite freezing temperatures and drastic seasonal changes in soil moisture and light intensity. We monitored photosynthetic capacity and the functional status of the vascular system for over a year and found that despite losing over 60 % of their water transport capacity from freeze–thaw induced cavitation, photosynthesis recovered in the spring. We found that localized, frost-triggered frond flexibility allows this species to lay flat on the ground and maintain warmer leaf temperatures, a process facilitated by highly flexible vascular bundles that bend without disrupting the water conducting pathway.

Late embryogenesis abundant (LEA) group 1 (LEA_1) proteins are intrinsically disordered proteins (IDPs) that play important roles in protecting plants from abiotic stress. Their protective function, at a molecular level, has not yet been fully elucidated, but several studies suggest their involvement in membrane stabilization under stress conditions. In this paper, the soybean LEA_1 protein PM1 and its truncated forms (PM1-N: N-terminal half, PM1-C: C-terminal half) were tested for the ability to protect liposomes against damage induced by freeze-thaw stress. Turbidity measurement and light microscopy showed that full-length PM1 and PM1-N, but not PM1-C, can prevent freeze-thaw-induced aggregation of POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) liposomes and native thylakoid membranes, isolated from spinach leaves (Spinacia oleracea). Particle size distribution analysis by dynamic light scattering (DLS) further confirmed that PM1 and PM1-N can prevent liposome aggregation during freeze-thaw. Furthermore, PM1 or PM1-N could significantly inhibit membrane fusion of liposomes, but not reduce the leakage of their contents following freezing stress. The results of proteolytic digestion and circular dichroism experiments suggest that PM1 and PM1-N proteins bind mainly on the surface of the POPC liposome. We propose that, through its N-terminal region, PM1 functions as a membrane-stabilizing protein during abiotic stress, and might inhibit membrane fusion and aggregation of vesicles or other endomembrane structures within the plant cell.

Corneal penetration is a key rate limiting step in the bioavailability of topical ophthalmic formulations that incorporate poorly permeable drugs. Recent advances have greatly aided the ocular delivery of such drugs using colloidal drug delivery systems. Ribavirin, a poorly permeable BCS class-III drug, was incorporated in bioadhesive multiple W/O/W microemulsion (ME) to improve its corneal permeability. The drug-loaded ME was evaluated regarding its physical stability, droplet size, PDI, zeta potential, ultrastructure, viscosity, bioadhesion, in vitro release, transcorneal permeability, cytotoxicity, safety and ocular tolerance. Our ME possessed excellent physical stability, as it successfully passed several cycles of centrifugation and freeze&ndash, thaw tests. The formulation has a transparent appearance due to its tiny droplet size (10 nm). TEM confirmed ME droplet size and revealed its multilayered structure. In spite of the high aqueous solubility and the low permeability of ribavirin, this unique formulation was capable of sustaining its release for up to 24 h and improving its corneal permeability by 3-fold. The in vitro safety of our ME was proved by its high percentage cell viability, while its in vivo safety was confirmed by the absence of any sign of toxicity or irritation after either a single dose or 14 days of daily dosing. Our ME could serve as a vehicle for enhanced ocular delivery of drugs with different physicochemical properties, including those with low permeability.

Background Frequent freeze-thaw phenomena, together with widely used deicing salt and intense acid precipitation, often occur in northeastern China, causing damage to various aspects of plants, such as the permeability of biological membranes, osmotic adjustment, and photosystems. Aiming to explore the resistance of alfalfa to freezing-thawing (F), acid precipitation (A) and deicing salt (D), this study used Medicago sativa cv. Dongmu-70 as the experimental material, and the contents of malondialdehyde (MDA), soluble protein, soluble sugars, proline and chlorophyll were evaluated. Results As the temperature decreased, the MDA content in the seedlings of the group under combined stress (A-D-F) increased and was significantly higher than that of group F (by 69.48 ~ 136.40%). Compared with those in the control (CK) group, osmotic substances such as soluble sugars and proline in the treatment groups were higher, while the soluble protein content was lower. The chlorophyll contents in the seedlings of the treatment groups were lower than those of the CK group; however, the chlorophyll content displayed a non-significant change during the free-thaw cycle. Conclusion Injury to the permeability of the biological membranes and photosystems of alfalfa results from stress. Moreover, alfalfa maintains osmotic balance by adaptively increasing the potential of osmotic substances such as soluble sugars and proline. Furthermore, the influence of stress from freezing-thawing and deicing salt is highly substantial, but the combined stresses of acid precipitation with the two factors mentioned above had little effect on the plants.

Sterilisation and preservation of vesicle formulations are important considerations for their viable manufacture for industry applications, particular those intended for medicinal use. Here, we undertake an initial investigation of the stability of hybrid lipid-block copolymer vesicles to common sterilisation and preservation processes, with particular interest in how the block copolymer component might tune vesicle stability. We investigate two sizes of polybutadiene-block-poly(ethylene oxide) polymers (PBd12-PEO11 and PBd22-PEO14) mixed with the phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) considering the encapsulation stability of a fluorescent cargo and the colloidal stability of vesicle size distributions. We find that autoclaving and lyophilisation cause complete loss of encapsulation stability under the conditions studied here. Filtering through 200 nm pores appears to be viable for sterilisation for all vesicle compositions with comparatively low release of encapsulated cargo, even for vesicle size distributions which extend beyond the 200 nm filter pore size. Freeze-thaw of vesicles also shows promise for the preservation of hybrid vesicles with high block copolymer content. We discuss the process stability of hybrid vesicles in terms of the complex mechanical interplay between bending resistance, stretching elasticity and lysis strain of these membranes and propose strategies for future work to further enhance the process stability of these vesicle formulations.

Freeze–thaw problems need to be solved urgently for the construction of projects in the alpine mountain areas. Freeze–thaw cycle tests with different cycles were carried out after water filled in the crack. Combined with the theory of frost heaving mechanics and fracture mechanics, the failure modes and mechanical characteristics of crack growth are analyzed after the freeze–thaw cycle test. The research results showed the crack growth increase with the number of freezing–thawing cycles. Cracked rock failure types are divided into four types. The Poisson's ratio, elastic modulus of rock and water-ice medium, and the equivalent volume expansion coefficient of water–ice medium determine the size of frost heaving force generated in fractured rock. The upper-saturated crack of limestone and red sandstone produces pure mode-I fracture under the action of the freeze–thaw cycle. The cracks in the fractured rock mass will extend along the direction of this structural plane when there is a visible weak structural surface in the rock mass. These research results can provide a reference for the freezing and thawing splitting effect caused by rainwater infiltration in mountainous alpine areas.

Freeze-thaw cycles impact the amount of aggregation observed in antibodies and Fc-fusion proteins. Various formulation strategies are used to mitigate the amount of aggregation that occurs upon putting a protein solution through a freeze-thaw cycle. Additionally, low pH solutions cause native antibodies to unfold, which are prone to aggregate upon pH neutralization. There is great interest in the mechanism that causes therapeutic proteins to aggregate since aggregate species can cause unwanted immunogenicity in patients. Herein, an increase in aggregation is reported when the pH is adjusted from pH 3 up to a pH ranging from pH 4 to pH 7 during the thaw process of a frozen antibody solution. Raising the pH during the thaw process caused a significant increase in the percent aggregation observed. Two antibodies and one Fc-fusion protein were evaluated during the pH jump thaw process and similar effects were observed. The results provide a new tool to study the kinetics of therapeutic protein aggregation upon pH increase. Keywords: Monoclonal antibodies, Freeze–thaw, Protein aggregation, Protein stability

PVA hydrogels obtained by freeze-thaw technique find important applications in regenerative medicine and controlled drug delivery technologies. The novelty of this contribution is the establishment of the cross-dependency of kinetics and thermodynamics parameters of swelling and dissolution of PVA hydrogels with the freeze-thaw process main variables. The work also establishes cross-correlations between the freeze-thaw process conditions, the gel microstructure and the properties of obtained hydrogel/hydrosoluble PVA materials. The conditions of the freeze-thaw process were selected by following an experimental design. The time evolution of the water up-take of PVA hydrogels was measured and used as main raw data generator. A 4-D surface response of the swelling and dissolution parameters in the space of freeze-thaw process variables was obtained and analyzed in terms of the resulting hydrogel and hydrosoluble polymeric structures. The 4-D surface response in the space of freeze-thaw process variables can predict very precisely the swelling and dissolution of PVA systems and their conditions for developing fully crosslinked hydrogel networks to fully hydrosoluble polymeric bodies. Fil: Daza Agudelo, Jorge Ivan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Badano, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Rintoul, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina

In outdoor applications, textile reinforced cementitious composites (TRCs) are susceptible to varying weathering conditions. To guarantee their performance during the entire life-time, it is necessary to evaluate the long-term behaviour. In this paper, the mechanical behaviour of reference specimens is compared to aged specimens, which are subjected to heat-rain and/or freeze-thaw cycles. Results show that subjection to heat-rain cycles leads to a larger degradation of the tensile behaviour compared to subjection to freeze-thaw cycles. Besides the macroscopic tensile behaviour, also the cracking behaviour is evaluated. Analysis shows that cracks are formed at lower stress levels after being subjected to environmental loading.

Composite cements offer low carbon alternatives to conventional CEM I. These binders also generally tend to perform better than CEM I in aggressive chemical environments. However, their freeze-thaw resistance, evident through surface scaling and internal damage is usually impaired. Postulated theories on freeze-thaw induced damage do not fully explain the origin of this weakness in composite cement concretes. This paper systematically presents the phase assemblage changes associated with the freeze-thaw of concrete specimen made from composite cements with and without limestone. The freeze-thaw test was performed on concrete according to CIF method based on CEN/TR 15177 and the corresponding cement pastes characterized by X-ray powder diffraction (XRD) and thermogravimetric analysis (TGA). In all investigated composite cements, portlandite was already depleted after the 7d capillary suction. The implications of this and other modified assemblages during the conditioning and the freeze-thaw test are consequently discussed.

Scientific and technological researches are devoted to obtain materials capable of retaining different kinds of pollutants, contributing to contamination solutions. In this context, hydrogels have emerged as great candidates because of their excellent absorption properties as well as good mechanical, thermal and chemical properties. More specifically, ferrogels (magnetic gels) present the extra advantage of being easily manipulated by a permanent magnet. Here, we present the results derived from the application of ferrogels as efficient tools to extract heavy metal pollutants from wastewater samples. The gels were prepared following the method of freezing and thawing of a polyvinyl alcohol aqueous solution with magnetic nanoparticles coated with polyacrylic acid. Ferrogels were fully characterized and their ability to retain Cu2+ and Cd2+, as model heavy metals, was studied. Thus kinetics and mechanisms of adsorption were evaluated and modeled. The concentration of MNPs on the PVA matrix was key to improve the adsorption capability (approximately the double of retention is improved by the MNPs addition). The adsorption kinetics was determined as pseudo-second order model, whereas the Langmuir model was the most appropriate to explain the behavior of the gels. Finally reuse ability was evaluated to determine the real potential of these materials, the ferrogels demonstrated high efficiency up to about five cycles, retaining about 80–90% of their initial adsorption capability. All the results indicated that the materials are promising candidates able to compete with the commercial technology regarding to water remediation. Fil: Areal, Maria Pia. Universidad Nacional de Mar del Plata; Argentina Fil: Arciniegas Vaca, Magda Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: Horst, María Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Lassalle, Verónica Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Sánchez, Francisco Homero. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina Fil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: Gonzalez, Jimena Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina

Cold recycling mixtures with foamed asphalt is one of the green and environmental-friendly construction technology in pavement rehabilitation. Most of the pavement recycling materials could be utilized with this kind of technology. Water, cement, aggregate and foamed asphalt will be added into the recycling asphalt pavement materials at the room temperature during the production of cold recycling mixtures. However, adding water into the mixtures may have a negative effect on the adhesion among foamed asphalt, new aggregate and recycling asphalt pavement materials. Especially in cold regions, the existence of excessive water in the mixtures may introduce the freeze-thaw durability issues during the winter-spring cycle. Therefore, it is important to clarify this durability issue of the foamed asphalt cold recycling mixtures in cold regions. In this study, an expressway pavement rehabilitation project with foamed asphalt cold recycling mixtures in the north of China had been selected to be test road. After initial material design in lab, the foamed asphalt cold recycling mixtures had been paved as the base layer. Then the field coring had been conducted, at the end of curing time and also after a freeze-thaw cycle. The performance tests on these coring samples indicate that the effect of freeze-thaw on the durability of the foamed asphalt cold recycling mixtures can not be neglected. The indirect tensile strength at dry and wet conditions, the modulus, and the fracture properties of the foamed asphalt cold recycling mixtures all had an obvious deterioration after undergoing the winter-spring cycle. Therefore, more structural frozen-resistant protection behaviors and advanced material design should be researched in the future.

Freeze-thaw weathering changes the pore structure, permeability, and groundwater transportation of rock material. Meanwhile, the change in rock material structure deduced by frost heaving deteriorates mechanical properties of rock material, leading to instability and insecurity of mine slopes in cold regions. In this paper, rock-like specimens containing prefabricated cracks at different angles and having undergone various freeze-thaw cycles are used as the object. Their pore structure, compressive mechanical properties, strain energies, failure characteristics, and the connection between pore structure and mechanical properties are analyzed. Results show that the porosity, spectrum area of mesopores, and spectrum area of macropores increase with the increase in freeze-thaw cycles, while crack angle shows no obvious influence on pore structure. Peak stress and elastic modulus drop with the increase in freeze-thaw cycles, while peak strain shows an increasing trend. Peak stress and elastic modulus decrease in the beginning, and then increase with the increase in crack angle, while peak strain shows a reverse trend. Elastic strain energy and pre-peak strain energy drop with the increase in freeze-thaw cycles. Elastic strain energy decreases first, and then increases with the increase in crack angle. The correlation between the spectrum area of macropores and elastic modulus is the strongest among different pores. Elastic modulus and peak stress decrease with the increase in macropore spectrum area, and peak strain increases with the increase in macropore spectrum area.

The design of concrete durability is normally based on the assessment of its performance when subject to a single deterioration mechanism. In reality, concrete structures are subject to varying environmental exposure conditions which often results in multi-deterioration mechanisms occurring. The Nordic climate, with cold harsh winters, poses a severe challenge to the long-term durability of concrete. The most common deterioration mechanisms are freeze-thaw damage, carbonation and chloride induced corrosion. Research is now more focused on the assessment of coupled deterioration mechanisms. For instance, evaluating how cracks resulting from freeze-thaw influence chloride ingress, or how carbonation changes the surface properties and thereby influencing freeze-thaw scaling and chloride penetration. This paper presents the results of research projects at VTT focusing on coupling deterioration mechanisms. These research projects have built on several decades of concrete durability research at VTT, including 15 years of field station studies. The durability of the concretes has been assessed using both accelerated laboratory testing and also from in situ exposure results from field stations. This research has contributed to the development of concrete performance models and service life tools, supporting a holistic approach for deterioration assessment.

This paper presents the results of an experimental program aimed at the assessment of the freeze–thaw (F–T) resistance of concrete based on the evaluation of fracture tests accompanied by acoustic emission measurements. Two concretes of similar mechanical characteristics were manufactured for the experiment. The main difference between the C1 and C2 concrete was in the total number of air voids and in the A300 parameter, where both parameters were higher for C1 by about 35% and 52%, respectively. The evaluation of the fracture characteristics was performed on the basis of experimentally recorded load–deflection and load–crack mouth opening displacement diagrams using two different approaches: linear fracture mechanics completed with the effective crack model and the double-K model. The results show that both approaches gave similar results, especially if the nonlinear behavior before the peak load was considered. According to the results, it can be stated that continuous AE measurement is beneficial for the assessment of the extent of concrete deterioration, and it suitably supplements the fracture test evaluation. A comparison of the results of fracture tests with the resonance method and splitting tensile strength test shows that all testing methods led to the same conclusion, i.e., the C1 concrete was more F–T-resistant than C2. However, the fracture test evaluation provided more detailed information about the internal structure deterioration due to the F–T exposure.

Storing platelet-rich plasma (PRP) for future use is a compelling approach, presuming the retention of biological properties is maintained. However, certain factors in PRP preparations have deleterious effects for the treatment of certain musculoskeletal conditions. The purpose of this study was to measure and compare matrix metalloproteinase protein (MMP) concentrations between fresh and freeze-thawed leukocyte-rich PRP (LR-PRP) inactivated (LR-I) and activated (LR-A) preparations, and leukocyte-poor PRP (LP-PRP) inactivated (LP-I) and activated (LP-A) preparations. A volume of 60 mL of whole blood was drawn from 19 healthy donors. LP-I and LR-I samples were processed using a manual extraction and centrifugation methodology. LP-A and LR-A products were activated with 10% CaCl2 and recombinant thrombin. Blood fractions were either immediately assayed and analyzed or stored at −80 °C for 24, 72 and 160 h. Multiplex immunoassay was used to measure MMP-1, MMP-2, MMP-3, MMP-9, MMP-10, and MMP-12. MMP-1 concentrations increased in LR-A (p &lt, 0.05) and MMP-9 significantly increased in LR-I (p &lt, 0.05), while MMP-2 significantly decreased in LR-I (p &lt, 0.05) and MMP-3 concentrations significantly decreased in LR-A (p &lt, 0.05). MMP-12 concentrations also significantly decreased in LR-I (p &lt, 0.05) from baseline concentrations. There were no significant differences between LP-A and LP-I preparations and MMP concentrations. MMP-10 concentrations in all PRP samples compared to each freezing time point were also not significantly different. MMPs regulate components of the extracellular matrix (ECM) in the remodeling phase of musculoskeletal injury. In this study, we observed a significant increase and decrease in MMP concentrations in response to a single freeze–thaw cycle in inactivated PRP and activated PRP preparations. This evidence contributes to the growing body of literature on the optimization of PRP preparation and storage strategies prior to delivery. Our findings suggest that specific PRP preparations after a single freeze–thaw may be more advantageous for certain musculoskeletal applications based on the presence of MMP concentrations.

The use of waste materials in concrete production is important because of the recycling of these materials. In this context, the use of both geopolymer binder and recycled concrete aggregate (RCA) becomes important. For this purpose, in this study, ground granulated blast furnace slag (GGBFS) based geopolymer concrete containing RCA was designed and freeze–thaw (F-T) and sulfate resistance of these samples were determined. In the production of geopolymer concrete, three different binder contents (300, 400 and 500 kg/m3) and five different ratios of RCA (0, 25, 50, 75 and 100%) were used. Samples that completed curing period were exposed to 100F-T cycles and two sulfate solutions (3% MgSO4 and 1.5% Na2SO4 + 1.5% MgSO4). Compressive strength, ultrasonic pulse velocity (UPV), weight change and sorptivity values ​​of these samples were determined. At the same time, these results were interpreted together with microstructure analysis (SEM and EDS). An exponential relationship was found between Ca/Si and Si/Al ratios of the samples and their compressive strength. Increasing in Ca/Si ratio and decreasing in Si/Al ratio caused an increase in compressive strength. As the binder content amount increased, the resistance of the samples against F-T cycles and sulfate solutions increased. With the increasing RCA ratio in the samples, there were increases in strength losses, but these losses were low and indicated that RCA was suitable for use in geopolymer concrete production. © 2021 Elsevier Ltd

Genetically modified autologous T cells have become an established immunotherapy in the fight against cancer. The manufacture of chimeric antigen receptor (CAR) and αβ-T cell receptor (TCR) transduced T cells poses unique challenges, including the formulation, cryopreservation and fill–finish steps, which are the focus of this review. With an increasing number of marketing approvals for CAR-T cell therapies, comparison of their formulation design and presentation for administration can be made. These differences will be discussed alongside the emergence of automated formulation and fill-finish processes, the formulation design space, Monte Carlo simulation applied to risk analysis, primary container selection, freezing profiles and thaw and the use of dimethyl sulfoxide and alternative solvents/excipients as cryopreservation agents. The review will conclude with a discussion of the pharmaceutical solutions required to meet the simplification of manufacture and flexibility in dosage form for clinical treatment.

SARS-CoV-2 RNA in wastewater settled solids is associated with COVID-19 incidence in sewersheds and therefore, there is a strong interest in using these measurements to augment traditional disease surveillance methods. A wastewater surveillance program should provide rapid turn around for sample measurements (ideally within 24 hours), but storage of samples is necessary for a variety of reasons including biobanking. Here we investigate how storage of wastewater solids at 4°C, -20°C, and -80°C affects measured concentrations of SARS-CoV-2 RNA. We find that short term (7-8 d) storage of raw solids at 4°C has little effect on measured concentrations of SARS-CoV-2 RNA, whereas longer term storage at 4°C (35-122 d) or freezing reduces measurements by 60%, on average. We show that normalizing SARS-CoV-2 RNA concentrations by concentrations of pepper mild mottle virus (PMMoV) RNA, an endogenous wastewater virus, can correct for changes during storage as storage can have a similar effect on PMMoV RNA as on SARS-CoV-2 RNA. The reductions in SARS-CoV-2 RNA in solids during freeze thaws is less than those reported for the same target in liquid influent by several authors.

To solve the problem of black ice, many studies are being carried out. The key in recent days is enhancing the thermal conductivity of concrete. In this study, to improve the thermal conductivity, silicon carbide was used to substitute 50% and 100% of the fine aggregate. In addition, steel fiber is not only for enhancing the mechanical properties but could enhance thermal conductive material. Hence, the arched-type steel fiber was used up to a 1% volume fraction in this study. Furthermore, graphite was used for 5% of the volume fraction for enhancing the thermal conductivity. However, thermal damage would occur due to the difference in thermal conductivity between materials. Therefore, the thermal durability must be verified first. The target application of the concrete in this study was its use as road paving material. To evaluate the thermal durability, freeze–thaw and rapid cyclic thermal attacks were performed. The thermal conductivity of the specimens was increased with the increase in thermal conductive materials. Graphite has already been reported to have a negative effect on mechanical properties, and the results showed that this was the case. However, the steel fiber compensated for the negative effect of graphite, and the silicon carbide provided a filler effect. Graphite also had a negative effect on the freeze–thaw and rapid cyclic thermal attack, but the steel fiber compensated for the reduction in thermal durability. The silicon carbide also helped to improve the thermal durability in the same way as steel fiber. Comprehensively, the steel fiber enhanced all of the properties of the tests. Using 100% silicon carbide was considered the acceptable range, but 50% of silicon carbide was the best. Graphite decreased all the properties except for the thermal conductivity. Therefore, the content of graphite or using other conductive materials used should be carefully considered in further studies.

The present work investigates the effect of freeze–thaw cycles on the porosity of three mixtures of road concrete containing blast furnace slag in comparison with two mixtures made with conventional materials. The main technique used in our investigations is nuclear magnetic resonance (NMR) relaxometry. This permitted the extraction of information with respect to the freeze–thaw effect on pore-size distribution, which influences both the mechanical strength and the molecular transport through the material. Moreover, by using this technique, the structure of the air voids was analyzed for the entire pore system in the cement paste and the aggregate particles. The samples under study were first dried in a vacuum oven and then saturated with water or cyclohexane where the distribution of the transverse relaxation times of the protons was recorded. The NMR relaxation measurements were performed on samples extracted from specimens maintained at 300 freeze–thaw cycles and on control samples extracted from specimens kept in water during the freeze–thaw period. Scanning Electron Microscopy (SEM) was used to analyze the microstructure of concrete samples in order to obtain information about the pore sizes and the distance between them. The results from the NMR relaxation measurements were consistent with those obtained by using standard techniques for determining the porosity and the freeze–thaw resistances. The investigations made it possible to establish the optimal composition of blast furnace slag that can be incorporated into road concrete compositions. This non-invasive technique can also complete standard techniques for assessing the porosity and the progress of internal cracks during the freeze–thaw test.