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Aluminium production needs the most energy‐intensive technologies among all the metal processing sectors. During the process of aluminium profile extrusion, the whole production line needs bulk electricity, and the mold inside the extrusion equipment needs robust cold energy for rapid cooling of the metal surface. This paper presents a new combo‐transmission that can simultaneously deliver cold energy together with electricity to the aluminium profile extrusion line. Thanks to the superiority of virtually zero loss and compact size, the powerful superconducting cable is used to replace the conventional copper cable. The entire superconducting cable assembly is fully installed into a cryogenic pipeline and cooled by liquid nitrogen at 77 K. In addition to keeping a favourable cryogenic environment for the superconducting cable, liquid nitrogen can also provide a large amount of cold energy for cooling the metal surface. For a typical 100 MN aluminium extrusion production line, the design and optimization of 10 kA class superconducting cable with the pipeline cooling system for aluminium production are presented in detail. The simulation results and comparisons show that the total energy loss of superconducting transmission is about 46% of conventional copper cable, and the energy saved in a year can be up to about 240.6 MWh. Moreover, the net profit increases almost linearly along with the increases of the extrusion speed when the liquid nitrogen cooling is applied to the 100 MN production line. For the case of 23% increase in extrusion speed, the net profit can be up to 1.48 M$ in a year. Overall, the novel design, technical evaluation, and economic analysis of the combo‐transmission system (cold energy + electricity) can provide a promising solution for future high‐dense aluminium production sectors.

Background: The five antigens of the Yt blood group system are located on the membrane GPI‐linked erythrocyte acetylcholinesterase (AChE‐E), which is implicated in a range of clinical issues, including sleep apnoea and neurotoxin poisoning. Conformational changes associated with different Yt antigens, as well as the storage of red cells, may affect AChE‐E activity. Direct analysis of AChE‐E presents unique challenges that may be overcome by electrochemical measurement using low‐cost electron‐mediated screen‐printed carbon electrodes (SPCEs) under suitable amperometric conditions. Aims: We present the electrochemical analysis of AChE‐E activity of five different Yt phenotypes, the effect on AChE‐E of red cell refrigeration over a four‐week timeframe and storage by freezing. The efficacy of electron‐mediated SPCEs is examined in relation to the potential interferences and electrode‐fouling. Methods: SPCEs containing the electron mediator (cobalt phthalocyanine) were manufactured on a plastic substrate, each in association with a screen‐printed Ag/AgCl counter/reference electrode in a two‐electrode format. Whole blood samples were initially washed to remove butyrylcholinesterase and resuspended in PBS. AChE‐E activity was assessed at 37⁰C using chronoamperometry at + 0 mV following the addition of acetylthiocholine chloride to the cell suspension. Ten Yt(a+b‐) and four Yt(a‐b+) donor samples were tested after collection and at two and four weeks storage at 4⁰C. Five Yt(a+b‐) and twenty Yt(a‐b+) were tested following freezing in liquid nitrogen. Samples with confirmed rare Yt phenotypes were evaluated to determine if the phenotype effected AChE‐E activity. The assay longevity and electrode viability were examined using eight of the samples representing the different Yt phenotypes over an extended duration of measurement. Results: SPCEs gave a consistent response in all samples tested without evidence of interference or fouling by the adherence of the cells to the electrode surface. The sensors were shown to operate continuously for a minimum of 60 minutes until the substrate became limiting. The reproducibility of the sensors (six replicates each of five samples) was 14% (RSD), which is typical for SPCEs in biological samples. An optimal assay duration of 120 seconds was selected. Compared to fresh samples, storage by freezing resulted in a loss of approximately 40% AChE‐E activity in Yt(a+b‐), whereas Yt(a‐b+) samples showed a 40% increase in enzyme activity. These differences occurred despite the almost identical conformation of the Yta and Ytb AChE‐E structure as studied by molecular dynamic calculations. Samples stored at 4⁰C showed a significant deterioration in AChE‐E activity within the first 14 days; a reduction of 35% for Yt(a+b‐) and 28% for Yt(a‐b+) (P < 0.01), followed by no significant change between 14 and 28 days of storage. The effect of rare Yt phenotypes was examined using stored frozen samples. AChE‐E activity differed markedly when compared to Yt(a+b‐); 82% higher in Yt(a‐b+) samples, 39% in YTLI– and 210% in YTOT–. An exception was YTEG–, which remained comparable to Yt(a+b‐). Summary/Conclusions: Mediated SPCEs were used effectively in the electrochemical measurement of AChE‐E activity, showing their potential for rapid low‐cost analysis of red cells. We showed that the activity of the enzyme was reduced with refrigeration, although the consequences of freezing were more varied in terms of Yt phenotype.

With the increasing popularity and burgeoning progress of space technology, the development of ultralow-temperature flexible functional materials is a great challenge. Herein, we report a highly emissive organic crystal combining ultralow-temperature elasticity and self-waveguide properties (when a crystal is excited, it emits light from itself, which travels through the crystal to the other end) based on a simple single-benzene emitter. This crystal displayed excellent elastic bending ability in liquid nitrogen (LN). Preliminary experiments on optical waveguiding in the bent crystal demonstrated that the light generated by the crystal itself could be confined and propagated within the crystal body between 170 and -196 °C. These results not only suggest a guideline for designing functional organic crystals with ultralow-temperature elasticity but also expand the application region of flexible materials to extreme environments, such as space technology.

The purpose of the study was to explore the microscopic and mesoscopic damage mechanisms of water‐bearing coal mass in the freeze‐thaw process with liquid nitrogen. For this purpose, by using a Zeiss microscope, a nonmetal ultrasonic velocity detector and a nuclear magnetic resonance (NMR) spectrometer, the changes in the structures of surface fractures and pores before and after coal masses with different moisture contents when subjected to freeze‐thaw treatment with liquid nitrogen (FTTLN) were tested. The result showed that under the freeze‐thaw effect of liquid nitrogen, the structures of surface fractures and internal pores of coal mass were both changed. Upon increasing the moisture content of the coal, the width of surface fractures increased; the surface fractures showed significant fractal characteristics: The higher the moisture content of the coal, the greater the rate of change of fractal dimension after FTTLN; the ultrasonic wave velocity in the coal mass gradually decreased after FTTLN, and the greater the moisture content, the more significant the decrease in ultrasonic wave velocity; under the freeze‐thaw effect of liquid nitrogen, the pore structure in the coal mass was transformed from micropores and small pores to mesopores and macropores and certain new micropores and small pores were generated. Upon increasing the moisture content of the coal mass, the peak area of micropores and small pores and their proportion decreased at first and then increased (reaching the minimum at 9.12% of moisture content); the peak area, peak area proportion, and porosity of mesopores and macropores always increased. The damage factor attained based on the width of fractures, longitudinal wave velocity, fractal dimension of surface fractures, and porosity was favorably correlated with the moisture content: With increasing moisture content, the coal mass became more severely damaged.

In recent years, liquid nitrogen (LN2) fracturing technology has been applied in coalbed methane (CBM) development. However, the impact of the liquid nitrogen freeze‐thaw process on the pore structure of anthracite coal has not yet been systematically investigated. In this study, nuclear magnetic resonance (NMR) analysis and scanning electron microscopy (SEM) imaging of coal samples after treatment with liquid nitrogen for different freezing times and freeze‐thaw cycles were performed to study the pore structure damage of anthracite subjected to the liquid nitrogen freeze‐thaw process as well as the variation in the porosity, fracture evolution, and permeability. The results show that the LN2 freeze‐thaw process can enlarge the pore size, enhance the pore connectivity, and form a fracture network on the surface of coal samples, which increases the total porosity, residual porosity, effective porosity, and permeability. This study provides a theoretical value for LN2 fracturing in the development of CBM.

Cryogenic nitrogen fracturing is an attractive method for stimulating underground reservoir, since it could favorably induce complex fracture due to the huge temperature difference with lower injection pressure and with the replacement of current water‐based fracturing fluid. However, the concern about whether cryogenic nitrogen would be overheated remains unrevealed in the engineering environment with large wellbore length. In addition, reservoir stimulation results are also related with the pressure state at bottom hole. Therefore, in this study, a mathematical model was proposed to predict the radial heat transfer and its influence on vertical pressure transmission in the wellbore with cryogenic nitrogen as fracturing fluid. The model fully couples the heat transfer, hydraulics, and the compressibility of nitrogen, and then, the calculation results were presented and analyzed through a case study. According to the results, the temperature of nitrogen increases too fast under conventional engineering conditions, and it changes into gaseous state at the depth lower than 100 m. Finally, the temperature difference between nitrogen and formation rock becomes too minimal to induce thermal stress at bottom hole. Due to the fast temperature increase, the density of nitrogen decreases too much, and the vertical pressure increasing rate by liquid nitrogen (1.66 MPa/km) is merely 18.2% that in carbon dioxide fracturing (9.13 MPa/km). The results indicate that utilization of special casing with much larger thermal resistance is an indispensable approach to realize the feasibility and advantages of cryogenic nitrogen fracturing.

RATIONALE Biobanks of patient tissues have emerged as essential resources in biomedical research. Optimal cutting temperature compound (OCT) blends have shown to provide stability to the embedded tissue and are compatible with spectroscopic methods, such as infrared (IR) and Raman spectroscopy. Data derived from omics-methods are only useful if tissue damage caused by storage in OCT blends is minimal and well understood. In this context, we investigated the suitability of OCT storage for heart tissue destined for liquid chromatography/tandem mass spectrometry (LC/MS/MS) lipidomic studies. METHODS To determine the compatibility of OCT storage with LC/MS/MS lipidomics studies. The lipid profiles of macaque heart tissue snap-frozen in liquid nitrogen or stored in an OCT blend were evaluated. RESULTS We have evaluated a lipid extraction protocol suitable for OCT-embedded tissue that is compatible with LC/MS/MS. We annotated and evaluated the profiles of 306 lipid species from tissues stored in OCT or liquid nitrogen. For most of the lipid species (95.4%), the profiles were independent of the storage conditions. However, 4.6% of the lipid species; mainly plasmalogens, were affected by the storage method. CONCLUSIONS This study shows that OCT storage is compatible with LC-MS/MS lipidomics of heart tissue, facilitating the use of biobanked tissue samples for future studies.

The waterless fracturing method with liquid nitrogen (LN2) as the fracturing fluid has been proposed and successfully applied in coalbed methane (CBM) production in recent years. The temperature of the coal reservoir sharply decreases, causing damage to the pore structure of the coal reservoir due to the ultralow temperature of LN2 during fracturing. Thus, in this paper, infrared thermal imaging (ITI) and nuclear magnetic resonance (NMR) were used to measure the temperature distribution and pore evolution law of anthracite coal. The results demonstrate that the temperature of the coal sample after being frozen by LN2 was far less than 0°C, which causes the internal water of the coal sample to freeze and turn into ice and produce a frost‐heave force. In addition, the temperature of the coal samples was not fixed but fluctuated, which led to the formation of a temperature gradient and induced thermal stress. The T2 spectra variation showed that LN2 freeze‐thaw cycles can promote the development of pores in coal samples and enhance the connectivity of pores. Some of the micropores gradually connect and expand to form a large number of mesopores and macropores under the influence of frost‐heave force and thermal stress. The total porosity, residual porosity, and effective porosity increase with the number of LN2 freeze‐thaw cycles. The NMR imaging directly reflects the change characteristics of the internal pore structure before and after LN2 freeze‐thaw, which provide a new way to reveal the pore evolution law of anthracite. These results show that LN2 freeze‐thaw cycles can damage the pore structure of anthracite coal, and a large number of mesopores and macropores are formed to provide channels for CBM migration, which improves the efficiency of LN2 fracturing.

Purpose: To develop an autonomous, in-bore, MR-compatible cryostat cooled with liquid nitrogen that provides full-day operation, and to demonstrate that the theoretical signal-to-noise benefit can be achieved for 13C imaging at 3 T (32.13 MHz). Methods: The cryogenic setup uses a vacuum-insulated fiberglass cryostat, which indirectly cools a cold finger where the RF coil is attached. The cryostat was evacuated before use and had a reservoir of liquid nitrogen for full-day operation. A 30 × 40 mm2 copper coil was mounted inside the cryostat with a 3-mm distance to the sample. Two examples of in vivo experiments of rat brain metabolism after a hyperpolarized [1-13C]pyruvate injection are reported. Results: A coil Q-factor ratio of Q88K/Q290K = 550/280 was obtained, and the theoretical SNR enhancement was verified with MR measurements. We achieved a coil temperature of 88 K and a preamplifier temperature of 77 K. A 2-fold overall SNR enhancement was achieved, compared with the best case at room temperature. The thermal performance of the coil was adequate for in vivo experiments, with an autonomy of 5 hours consuming 6 L of LN2, extendable to over 12 hours by LN2 refilling. Conclusion: Cryogenic surface coils can be highly beneficial for 13C imaging, provided that the coil-to-sample distance remains short. An autonomous, in-bore cryostat was developed that achieved the theoretical improvement in SNR.

Organic single crystals with elastic bending capability and potential applications in flexible devices and sensors have been elucidated. Exploring the temperature compatibility of elasticity is essential for defining application boundaries of elastic materials. However, related studies have rarely been reported for elastic organic crystals. Now, an organic crystal displays elasticity even in liquid nitrogen (77 K). The elasticity can be maintained below ca. 150 °C. At higher temperatures, the heat setting property enables us to make various shapes of crystalline fibers based on this single kind of crystal. Through detailed crystallographic analyses and contrast experiments, the mechanisms behind the unusual low-temperature elasticity and high-temperature heat setting are disclosed.

Purpose Raman scattering spectra can be thought of as the "fingerprints" of the investigated material. The purpose of this work was to link the absorbed doses of irradiated radiochromic film at the micrometer level with changes in their Raman spectra. Methods Raman spectra of irradiated GAFCHROMIC EBT3 film with doses ranging from 0 to 40 Gy were acquired. The excitation wavelengths used in the experiments (457.9 and 647.1 nm) coincided with electronic transitions of the active layer of the film. The effect of resonance Raman scattering enhanced Raman peaks in the resonance region. Spectra were taken in the range of room temperature to around the temperature of liquid nitrogen (-190°C). Results The Raman peak intensity redistribution is shown for films with different absorbed doses. The ratio of intensities of the 1445 cm-1 band with respect to the 1330 cm-1 band increases with the increase in absorbed dose. This allows building a dose calibration curve for the film. Conclusion The dose distribution of the irradiated film can be identified based on the intensity ratio of the 1445 and 1330 cm-1 bands by means of Raman mapping. This is a noninvasive and computerized readout method which provides micrometer resolution results for the film surface. This is beneficial in the use of radiochromic films as dosimeters for high-precision radiotherapies.

Stored biological materials should have minimal pre‐analytical variations in order to provide researchers with high‐quality samples that will give reliable and reproducible results, yet methods of storage should be easy to implement, with minimal cost and health hazard. Frozen tissue samples are a valuable biological resource. Here we compare different methods, such as liquid nitrogen (LN) or dry ice (DI), to a cheap and safe alternative using an aluminum platform (AP). Murine fresh liver and pancreas tissues were used with varying lengths of warm ischemia time. Quality assessment was based on histological evaluation, DNA and RNA extraction and quantification, and RNA degradation analysis, as well preservation of antigens for immunofluorescence, in a blinded manner. Both in superficial and deep tissue sections, based on histological assessment, AP is superior to DI, or as good as LN techniques in terms of presence of ice crystals, cutting artifacts, and overall quality/structural preservation. DNA and RNA were successfully extracted in reasonable quantities from all freezing techniques, but RNA degradation was seen for pancreas samples across all techniques. Immunofluorescence with cytokeratin8 (CK‐8), alpha smooth muscle actin (αSMA), CD3, and B220 shows equally good outcomes for AP and LN, which are better than DI. The aluminum platform is a cheap, yet reliable method to freeze samples, rapidly preserving histological, antigenic, and DNA/RNA quality. Wider testing is required across different sample types. © 2020 The Authors. Basic Protocol: Flash‐freezing fresh tissue with aluminum platform Alternate Protocol 1: Freezing fresh tissue with liquid nitrogen Alternate Protocol 2: Freezing fresh tissue with dry ice

Premise New sequencing technologies have facilitated genomic studies in green microalgae; however, extracting high-quality DNA is often a bottleneck for long-read sequencing. Methods and results Here, we present a low-cost, highly transferrable method for the extraction of high-molecular-weight (HMW), high-purity DNA from microalgae. We first determined the effect of sample preparation on DNA quality using three homogenization methods: manual grinding using a mini-pestle, automatic grinding using a vortex adapter, and grinding in liquid nitrogen. We demonstrated the versatility of grinding in liquid nitrogen followed by a modified cetyltrimethylammonium bromide (CTAB) extraction across a suite of aquatic- and desert-evolved algal taxa. Finally, we tested the protocol's robustness by doubling the input material to increase yield, producing per sample up to 20 μg of high-purity DNA longer than 21.2 kbp. Conclusions All homogenization methods produced DNA within acceptable parameters for purity, but only liquid nitrogen grinding resulted in HMW DNA. The optimization of cell lysis while minimizing DNA shearing is therefore crucial for the isolation of DNA for long-read genomic sequencing because template DNA length strongly affects read output and length.

Background: The effect of freezing (in liquid nitrogen at -196 °C , at -80 °C and at -20 °C) on the food matrix structure and the consequent effect on the bioaccessibility of total polyphenol content (TPC) and antioxidant activity (AA) of beetroot was investigated by an in vitro digestion method. The in vitro digestion involved incubation in simulated saliva followed by incubation in simulated gastric juice. Bioaccessibility of bioactive compounds was evaluated by measuring the TPC and the AA during in vitro digestion in both the beetroot matrix and the gastric juice.; Results: Release of TPC and AA of beetroot was higher in frozen samples (55 ± 5% for TPC and 68 ± 5% for AA) than in the fresh beetroot sample (∼46% for TPC and ∼53% for AA). The mass transfer kinetics were described by using a Weibull model with mean relative errors lower than 8.5% contributing to a better understanding of the influence of freezing on the bioaccessibility of bioactive compounds.; Conclusions: From the treatments tested in this study, freezing with liquid nitrogen resulted in the greatest increase in bioaccessibility of the antioxidant and phenolic compounds of beetroots. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.

Rutile, TiO2 is increasingly oxygen‐deficient on heating in air above ~700°C. The weight loss is generally too small for accurate measurement, but the electrical properties of quenched samples provide a sensitive qualitative indicator of oxygen content since their conductivity can vary by many orders of magnitude. The oxygen lost at high temperature is fully recovered if samples are cooled slowly. With rapid quenching, by dropping samples into liquid N2, the oxygen stoichiometry at high temperature is preserved to ambient and the resulting materials are kinetically stable but thermodynamically metastable. The lattice parameters of quenched samples showed an unusual dependence on quench temperature and, by implication, on oxygen stoichiometry. Lattice parameters increased with a small oxygen loss, δ; chemical expansion of the lattice occurred and is attributed to reduction in average Ti oxidation state and increase in Ti–O bond lengths. At higher δ, lattice parameters started to decrease giving a chemical contraction effect attributed to partial collapse of columns of edge‐sharing TiO6 octahedra in the rutile structure and elimination of oxygen vacancies by crystallographic shear plane formation. Oxygen‐deficient samples quenched from above 700°C were n‐type, as were samples annealed and measured at 650 and 700°C. Samples measured at 450‐500°C were p‐type and believed to be slightly oxygen‐rich; it is suggested that holes located on oxide ions at or near the sample surface arose from redox electron transfer between underbonded surface oxide ions and adsorbed O2 molecules. Samples annealed between 550 and 600°C showed cross‐over between n‐ and p‐type behavior.

Parahydrogen is a potentially significant source of hyperpolarization. However, a heat exchanger at an ultralow temperature, which is normally sustained wastefully using liquid nitrogen, is essential for the generation of hyperpolarized parahydrogen. In order to cut down on the use of liquid nitrogen, we employed a cryogenic storage dewar as the key component of our home-built parahydrogen generator, which lasted over 20 days with a single filling. Small concentrations of an unsaturated compound in a mixture were identified by hydrogenation in a principle-based experiment involving the use of hyperpolarization and phase difference. Less than 1 μl of styrene in 1 ml of chloroform was identified in a single scan with a 43 MHz benchtop nuclear magnetic resonance (NMR) spectrometer following hydrogenation with 50% parahydrogen. This method can potentially undergo a significant development through the use of high-field NMR techniques, higher parahydrogen concentrations, and increased scan times for data collection, among others. Because hydrogenation with parahydrogen induces a phase reversal during attachment to unsaturated CC bonds, it may be possible to detect many other unsaturated bonds in organic molecules. All in all, this study not only broadens the research on parahydrogen-based unsaturated-bond detection, but also facilitates the use of hyperpolarization by a broader range of researchers through the introduction of a long-lasting home-built parahydrogen generator.

Freezing preservation is one of the most effective methods used to maintain the flavour and nutritional value of fruit. This research studied the effects of different freezing conditions, -20 °C, -40 °C, -80 °C, and immersion in liquid nitrogen, on quality changes of freeze-thawed blueberries. The water distribution estimates of blueberries were measured based on low-field nuclear magnetic resonance (LF-NMR) analysis. The pectin content, drip loss, and fruit texture were also detected to evaluate quality changes in samples.; Results: The freezing curves of blueberry showed super-cooling points at -20 °C and - 40 °C, whereas super-cooling points were not observed at -80 °C or in liquid nitrogen. After freeze-thaw treatment, the relaxation time of the cell wall water (T21 ), cytoplasm water and extracellular space (T22 ), and vacuole water (T23 ) were significantly shortened compared to fresh samples, which suggested a lower liquidity. Although the freezing speed for samples immersed in liquid nitrogen was faster than other treatments, samples treated at -80 °C showed better quality regarding vacuole water holding, drip loss, and original pectin content retention.; Conclusion: This study contributed to understanding how freezing temperature affects the qualities of blueberries. The super-fast freezing rate might injure fruit, and an appropriate freezing rate could better preserve blueberries. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.

The open-circuit voltage (VOC ) of perovskite solar cells (PSCs) is reported to be significantly weakened by carrier loss at the film surface. Here, the moisture condensation at only the upper surface of perovskite films is controlled by constructing an ultralow surface temperature. Then, type-I band alignment can be formed at the surface grain boundaries due to the etching effect of trace amounts of condensed moisture. The beneficially constructed surface type-I band alignment can effectively repel carriers and return them to the inside of the grain, significantly avoiding the carrier loss at films surface. As a result, a superior carrier lifetime exceeding 2.5 µs is obtained and the VOC of PSC is remarkably boosted from 1.07 to 1.17 V. The minimum VOC deficit of only 0.39 V enables a substantial gain in power conversion efficiency (PCE) from 20.2% to 22.4% in one-step spin-coating methods. Moreover, this innovation is versatile and a champion PCE of 23.2% is also achieved in two-step spin-coating methods.

When measured at low temperature (79 K), the photoluminescence (PL) spectra from silicon wafers containing a diffused heavily doped layer exhibit a second peak due to band gap narrowing in the diffused region. This work aims to decompose this peak into components arising from the various doping concentrations within the diffused layer. Whilst the peak position of silicon band-to-band PL spectra changes significantly with the doping concentration in silicon, the shape of the spectra also varies strongly with doping concentrations due to the broadening effects of band-filling and band-tail states. By measuring PL spectra on a range of uniformly heavily doped wafers, we show that these changes in spectral position and shape can be accurately modelled for doping concentrations above 1 × 1019 cm−3 using simple parameterisations, with minimal impact of variations in excitation intensity or injection level. This allows the PL spectra for a range of arbitrary doping concentrations to be reconstructed. We then show that the PL spectra from a thermally boron-diffused wafer, in which the boron concentration changes with depth, can be reconstructed based on a superposition of PL spectra arising from the layers of different doping beneath the surface. Furthermore, the scaling factor for each layer can be accurately estimated based on the doping profile and the fraction of incident light absorbed in the layer.

The construction of liquid nitrogen gas storages and engineering structures in cold regions exposed reinforced concrete structures to low temperatures. This paper investigates the compressive strength of normal-weight concrete under low temperatures to −165°C through a 174-specimen test program. The key parameters studied in this test program included low temperature T ranging from −165 to +20°C, water/cement ratio ranging from 0.33 to 0.57, and water content Wc ranging from 0 to 6%. Their influences on the compressive strength of the concrete under low temperature were highlighted and analyzed. With the scanning electron microscope (SEM), the influence of these parameters on the microstructures of the concrete under low temperature was observed and presented. These test data and SEM analyses revealed the failure mechanism and provided proofs on the improvements of the compressive strength of the concrete under low temperature. Based on these test data, a mathematical model has developed to describe the relationship between the increasing factor of the compressive strength of the concrete under low temperatures and the influencing parameters of T, w/c ratio, and Wc. Finally, design equations are provided to predict the increasing factor of the compressive strength of the concrete under low temperature.

One of the best preservation method for long-term storage is drying. In this work, the influence of different drying methods on aroma and sensory profile of shiitake mushroom was evaluated. The drying methods tested were: convective drying (CD), freeze-drying (FD), vacuum-microwave drying (VMD), and a combination of convective pre-drying and vacuum-microwave finish-drying (CPD-VMFD).; Results: The volatile composition of fresh and dried shiitake mushrooms was analysed by SPME, GC-MS and GC-FID, and showed the presence of 71 volatile compounds, most of them present in all dried samples but with quantitative variation. The major volatile compounds in fresh shiitake were 1-octen-3-ol (20.2%), 2-octanone (20.7%), 1,2,4-trithiolane (9.8%), and 1,2,3,5,6-pentathiepane (8.2%). Drying of shiitake mushrooms caused significant losses of C8 compounds and cyclic sulfur compounds, such as 1,2,4-trithiolane (V31) and 1,2,4,5-tetrathiane (V57). Samples dried at CD 80 °C implied a relative short drying time (120 min), had the highest contents of total volatiles (1594 μg 100 g-1 ) and cyclic sulfur compounds (e.g. V57 126 μg 100 g-1 ), and the highest intensity of most of the key positive sensory attributes, such as inner colour (7.0), fresh shiitake flavour (6.7), and sponginess (6.2).; Conclusion: The best dehydration methods, resulting in the highest total concentrations of volatile compounds and high intensity of key sensory attributes were FD (if vacuum and liquid nitrogen facilities are available) and CD at 80 °C (for companies with vacuum and liquid nitrogen facilities). © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.

An energy-dispersive system is described for elemental mapping by X-ray fluorescence spectrometry. The present study describes the design of an X-ray fluorescence spectrometer and presents its performance in elemental mapping applications. The spectrometer is based on a new ring-shaped collimator with a pinhole in the center of it and a ring-shaped Am-241 isotope mounted in the collimator as a source for excitation of X-ray fluorescence. The photons were detected by high-resolution Si (Li) detector coupled to a multi-channel analyser and cooled by liquid nitrogen. In this study, we used two samples; one of them was made from pure elemental powders, and the second one was a piece of a stone and three types of maps were plotted. In the maps type one, the areas of the elements were shown with a single color. These maps only show the location of the elements in the sample. In the maps type two, the area of each element was shown with different colors because of the count (intensity) related to the area. In the third type of the maps for each element, depending on the elements' position on the sample, the counts were plotted in three dimensions. The areas with higher intensity have greater height, and areas with lower intensity have lower altitude. These two last types of maps provide information about the homogeneity or heterogeneity of the elemental distribution in the samples. The spectrometer can perform non-destructive analyses of samples and objects in the air. Copyright © 2017 John Wiley & Sons, Ltd.

Ultralow-density transparent porous bulk materials with densities of 5 mg cm−3 or less have only been obtained by supercritical drying. In this work, a simple method is reported for obtaining ultralow-density transparent porous beads with a diameter of several millimeters. In the method, a boehmite nanofiber dispersion (BNF sol) is dripped directly into liquid nitrogen and the beads are vacuum-dried. Normally, porous materials obtained via freeze drying exhibit strong light scattering due to structural nonuniformity and are not transparent. However, using dilute BNF as a skeleton structure suppressed the inhomogeneity due to aggregation during the dispersion medium crystallization. The lowest bulk density of the cryogel was 1.1 mg cm−3, and the visible light transmittance reached 90 %. By dispersing functional materials into the BNF sol before freezing, composite materials were obtained. The facile method can be expected to develop the field of functional porous materials.

Contents The objective was to assess the effect of cooling to different subzero temperatures around ice formation (−5°C) on dog sperm cryosurvival and plasma membrane fluidity. Semen was centrifuged, and sperm were resuspended in a Tris-egg yolk medium (3% glycerol). Diluted sperm were cooled from 22 to 5°C, and then, a Tris-egg yolk medium containing 7% glycerol was added (final concentration of 5% glycerol and 200 × 106 cells/ml). Sperm were packaged in 0.5-ml plastic straws, and equilibration was done 16 hr at 5°C before freezing. I. Straws (n = 47) at 5°C were exposed to nitrogen vapours to determine the freezing point. II. Other straws (from different ejaculates) processed as mentioned, were further cooled to −3, −5 or −7°C and immediately rewarmed in a water bath at 37°C. Motility, plasma membrane functionality and acrosome integrity were assessed. III. Other straws (from different ejaculates) processed as mentioned were further cooled to −3 or −5°C, frozen over nitrogen vapours and stored in liquid nitrogen for one month. Straws were thawed in a water bath at 38°C for 30 s. Motility, plasma membrane functionality, plasma membrane integrity, acrosome integrity, capacitation status and plasma membrane fluidity were assessed. Ice nucleation temperature was −14.3 ± 2.05°C (mean ± SD); cooling to +5, −3, −5 and −7°C, without freezing, produces no differences on sperm quality between target temperatures; cooling to +5, −3, and −5°C produced no differences on sperm survival and plasma membrane fluidity after freeze–thawing. In conclusion, cooling of dog spermatozoa to different subzero temperatures did not improve sperm cryosurvival and had no effect on plasma membrane fluidity after thawing.

SUMMARYBackground In the last few decades, various red blood cell (RBC) freezing techniques have been developed and improved to enable the preservation of erythrocytes for future use in pre-transfusion tests in reference immunohaematology laboratories. However, not all these techniques have been sufficiently evaluated for the preservation of blood group antigens. Objectives In this study, we evaluated the antigenic pattern of RBCs preserved by droplet freezing in liquid nitrogen in a blood bank context. Methods Blood samples were evaluated for the reactivity of blood group antigens after droplet freezing using the non-permeable cryoprotective agent polyvinylpyrrolidone (PVP) and sucrose–dextrose (S + D) solutions. Results No qualitative changes were observed in RBC reactivity after freezing and thawing for the antigens Fyb, Leb, C, E, Cw, Lua, Lub, Kpa, Kpb and Dia. However, cryopreservation using PVP resulted in a significant increase in reactivity of Fyb antigen on comparing fresh and frozen samples (P < 0·001). Conclusion The establishment of detailed protocols for cryopreservation of RBCs, which take into account the maintenance of antigenic characteristics, is necessary to increase security in pre-transfusion testing using frozen RBCs.

Janus particles with asymmetric crystals show great importance in optoelectronics and photocatalysis, but their synthesis usually requires complicated procedures. Here, an unexpected Janus vitrification phenomenon is observed in a droplet caused by the Leidenfrost effect at a cryogenic temperature, which is commonly regarded as symmetric. The Leidenfrost phenomenon levitates the droplet when it comes in contact with liquid nitrogen causing different cooling conditions on the droplet's top and bottom surfaces. It induces asymmetric crystallization in the droplet, forming a Janus vitrified particle with an asymmetric crystallization borderline after cooling, as further evidenced by cryotransmission electron microscopy (cryo-TEM) experiments. Theoretical analysis and experimental study indicate that the position of the asymmetric crystallization borderline is determined by the droplet radius and density, and the observation window of asymmetric crystallization borderline is determined by the chemical concentration. The finding reveals the asymmetric crystallization phenomenon in droplet vitrification for the first time, and provides a new insight for creating Janus particles through the Leidenfrost phenomenon.

Conventional adhesives often encounter interfacial failure in humid conditions due to small droplets of water condensed on surface, but spider silks can capture prey in such environment. Here a robust spider-silk-inspired wet adhesive (SA) composed of core-sheath nanostructured fibers with hygroscopic adhesive nanosheath (poly(vinylpyrrolidone)) and supporting nanocore (polyurethane) is reported. The wet adhesion of the SA is achieved by a unique dissolving-wetting-adhering process of core-sheath nanostructured fibers, revealed by in situ observations at macro- and microscales. Further, the SA maintains reliable adhesion on wet and cold substrates from 4 to -196 °C and even tolerates splashing, violent shaking, and weight loading in liquid nitrogen (-196 °C), showing promising applicability in cryogenic environments. This study will provide an innovative route to design functional wet adhesives.

We evaluated tools and methods for in situ freezing of cores in unconsolidated subsurface media. Our approach, referred to as cryogenic core collection (C3), has key aspects that include downhole circulation of liquid nitrogen (LN) via a cooling system, strategic use of thermal insulation to focus cooling into the core, and controlling LN back pressure to optimize cooling. Two cooling systems (copper coil and dual-wall cylinder) are described. For both systems, the time to freeze a single 2.5-foot (76-cm) long by 2.5-inch (63-mm) diameter core is 5 to 7 min. Frozen core collection rates of about 30 feet/day (10 m/day) were achieved at two field sites, one impacted by petroleum-based light nonaqueous phase liquids (LNAPLs) and the other by chlorinated solvents. Merits of C3 include (1) improved core recovery, (2) potential control of flowing sand, and (3) improved preservation of critical sediment attributes. Development of the C3 method creates novel opportunities to characterize sediment with respect to physical, chemical, and biological properties. For example, we were able to resolve water, LNAPL, and gas saturations above and below the water table. By eliminating drainage of water, gas and LNAPL saturations in the range of 6 to 23% and 1 to 3% of pore space, respectively, were measured in LNAPL-impacted intervals below the water table.

Rationale Stable isotope analysis can be used to obtain information on olive ridley sea turtles in the Mexican Central Pacific (MCP). Tissue samples such as scale, muscle, and blood are usually not analyzed immediately and are preserved in different substances such as ethanol, formalin, sodium chloride, the ideal being liquid nitrogen. Due to logistical reasons, the latter preservation method cannot always be used. The objective of the present study was to evaluate the efficiency of dimethyl sulfoxide (DMSO) as a preservation agent for later stable isotope analysis. Methods Forty-eight paired scale samples of olive ridley were collected in MCP waters and preserved in DMSO and liquid nitrogen. We determined their δ13C and δ15N values using a Carlo Erba 1108 elemental analyzer coupled to a ThermoFinnigan Delta Plus XP isotope ratio mass spectrometer (precision ±0.2‰ for each stable isotope). The mean isotopic ratios of each preservation method were compared. Results Significant differences were observed between the isotopic ratios of samples in the two preservatives. Samples preserved in DMSO resulted in more negative isotopic values than those in liquid nitrogen, and a correction factor was calculated. The correction factors were 2.1‰ for δ13C values and 0.8‰ for δ15N values. Conclusions DMSO is not equivalent to liquid nitrogen for the preservation of olive ridley scales to be used for isotopic analysis. If DMSO has to be used for logistical reasons a replicate sample should also be collected to be able to estimate a correction factor. Copyright © 2016 John Wiley & Sons, Ltd.

Liquid fuel fires occurring during industrial processes are serious safety concerns around the world due to their devastating impact on lives, the environment and property. In this study, a liquid nitrogen delivery system was set up to extinguish the oil pool fires in open space. Effects of liquid nitrogen flow rate, pipe diameter, and liquid nitrogen release distance on the suppression process were analyzed according to the mass loss, burning rate and temperature variations. When liquid nitrogen release distance was 0.50 m and pipe diameter was 0.04 m, fire extinguishing time was the shortest 1.6 s and the temperature decrease rate above the liquid fuel surface reached 275°C/s. Fuel surface cooling and blow off process were revealed through the experiments as two kinds of fire extinguishing mechanisms. Based on the flame images captured by high speed camera, the flame expansion phenomenon might occur early in liquid nitrogen injection, especially the situation of the higher flow rate of liquid nitrogen. Three approaches (ground fixed system, moving transportation, and directional transportation of liquid nitrogen) are provided for fire extinguishment of large scale fires. The results obtained provide important reference for the conduct of fire extinguishment for fires. © 2016 American Institute of Chemical Engineers Process Saf Prog, 2016

Liquid nitrogen for liquid fuel fires extinguishing is still a new and hot topic. Fire extinguishment behaviors of liquid nitrogen are not yet fully understood, and the related research is still in its infancy. In this article, a flexible liquid nitrogen jet system was set up to examine the process of liquid nitrogen interacting with the pool fire in an open space. The main objective of this article is to compare the extinguishment behaviors of vertical/horizontal jet of liquid nitrogen for extinguishing oil pool fires by the measurements of weight, thermocouples temperature, and infrared thermal image. As a result, experiment discovered that liquid nitrogen has a satisfactory performance for the pool firefighting. And the horizontal jet of liquid nitrogen is more effective than the vertical jet in terms of fire extinguishing time and the required amount of liquid nitrogen. The shape of fire flame during the period of horizontal liquid nitrogen jet was completely different from that during the period of vertical liquid nitrogen jet. The fire extinguishing mechanism of vertical/horizontal liquid nitrogen jet was revealed, respectively. © 2016 American Institute of Chemical Engineers Process Saf Prog, 2016

Contents To support conservation strategies in wild species, simple but highly reproducible procedures of sperm cryopreservation are required for an application under field conditions. We used epididymal sperm of the domestic cat to optimize a sperm freezing procedure for felid species, particularly questioning the demand for sperm cooling to 4°C. We equilibrated sperm during slow cooling to only 15 or 10°C in a Tes–Tris–fructose extender with final concentrations of 4.7% (v/v) glycerol and 10% (v/v) of the water-soluble fraction of hen's egg yolk (low-density lipoproteins). Subsequently, sperm were frozen over liquid nitrogen. Total and progressive motility (mean ± SD) after thawing was 60.7 ± 8.6% and 53.9 ± 9.6% in samples cooled to 15°C or 61.6 ± 9.5% and 55.3 ± 9.9% in samples cooled to 10°C. Therefore, a one-step addition of glycerol to sperm at room temperature together with the freezing extender, the use of cryovials (loaded with diluted sperm aliquots of 300 μl), an equilibration period of 40 min comprising slow cooling to 15°C at a rate of approximately −0.14 K/min before rapid freezing over liquid nitrogen, yielded satisfying results. Cooling, freezing and thawing rates were exactly characterized as a prerequisite for further optimization and to provide a repeatable protocol to other practitioners.

A method involving comprehensive two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry was developed and applied to the analysis of nitrogenous organic compounds present in mainstream cigarette smoke trapped on self-designed equipment. The samples were prepared using low-temperature solvent extraction under liquid nitrogen and analyzed by comprehensive two-dimensional gas chromatography with high-resolution time-of-flight mass spectrometry. Important experimental parameters, such as the type and volume of the extraction solvent and flow rate of smoking, were optimized to improve the analysis parameter. The results indicated that 180 mL of diethyl ether in the low-temperature solvent extraction apparatus system with a 4 mL/min smoke flow rate were the optimal conditions. Then, 85 nitrogenous organic compounds were identified and quantified using a mass spectral library search, accurate mass ion and N-rules of a molecular formula for nitrogen compounds. Finally, a comparison of the low temperature solvent extraction method and Cambridge filter pad method indicated that more peaks, a higher peak volume and better repeatability were obtained using the low-temperature solvent extraction method.

High-quality Gd60Co15Al25 microwires with an average diameter of 40 µm were successfully fabricated by the melt-extraction method. The as-cast microwires undergo a second-order paramagnetic to ferromagnetic (PM–FM) transition at ∼100 K. Large values of the magnetic entropy change (−ΔSM ∼9.73 J kg−1 K−1) and the refrigerant capacity (RC ∼732 J kg−1) are achieved for a field change of 5 T. A careful analysis of critical exponents near the PM–FM transition indicates the significant effects of structural disorder on the long-range ferromagnetic interaction and the magnetocaloric response of the microwires. The excellent magnetocaloric properties make the Gd60Co15Al25 microwires very promising for use in magnetic refrigerators operating in the liquid nitrogen temperature range.

This article is focused on the study of cooling rate effects on the thermal, structural, and microstructural properties of hydroxyapatite (HAp) obtained from bovine bone. A three-step process was used to obtain BIO-HAp: hydrothermal, calcinations, and cooling. Calcined samples in a furnace and cooling in air (HAp-CAir), water (HAp-CW), and liquid nitrogen (HAp-CN2), as well as an air cooled sample inside the furnace (HAp-CFAir), were studied. According to this study, the low cooling rate that was achieved for air cooled samples inside the furnace produce single crystal BIO-HAp with better crystalline quality; other samples exhibited polycrystalline structures forming micron and submicron grains. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2015.

Rationale The separation and purification of oxygen–argon mixtures are critical in the high-precision analysis of Δ17O and δ(O2/Ar) for geochemical applications. At present, chromatographic methods are used for the separation and purification of oxygen–argon mixtures or pure oxygen, but these methods require the use of high-purity helium as a carrier gas. Considerable interest has been expressed in the development of a helium-free cryogenic separation of oxygen–argon mixtures in natural air samples. Methods The precise and simplified cryogenic separation of oxygen–argon mixtures from natural air samples presented here was made possible using a single 5A (30/60 mesh) molecular sieve column. The method involves the trapping of eluted gases using molecular sieves at liquid nitrogen temperature, which is associated with isotopic fractionation. We tested the proposed method for the determination of isotopic fractionations during the gas exchange between water and atmospheric air at equilibrium. The dependency of fractionation was studied at different water temperatures and for different methods of equilibration (bubbling and stirring). Isotopic and molecular fractionations during gas desorption from molecular sieves were studied for different amounts and types of molecular sieves. Results Repeated measurements of atmospheric air yielded a reproducibility (±SD) of 0.021 ‰, 0.044 ‰, 15 per meg and 1.9 ‰ for δ17O, δ18O, Δ17O and δ(O2/Ar) values, respectively. We applied the method to determine equilibrium isotope fractionation during gas exchange between air and water. Consistent δ18O and Δ17O results were obtained with the latest two studies, whereas there was a significant difference in δ18O values between seawater and deionized water. Conclusions We have revised a helium-free, cryogenic separation of oxygen–argon mixtures in natural air samples for isotopic and molecular ratio analysis. The use of a single 13X (1/8" pellet) molecular sieve yielded the smallest isotopic and molecular fractionations, and this fractionation by molecular sieves can be corrected by the amount of molecular sieve used in the experiment. The reproducibility of the method was tested by the measurement of the oxygen isotope ratios of dissolved oxygen at equilibrium with atmospheric air. We confirmed that the choice of methods for making air-equilibrated water was not related to the magnitude of isotope fractionation, whereas there was a difference between seawater and deionized water. Copyright © 2015 John Wiley & Sons, Ltd.

We report herein the results of our investigations on the synthesis of transition-metal dichalcogenide (TMDC) semiconductor layered materials of MoS2, WS2, MoSe2, and WSe2 by the rapid quenching method. The bulk powders were added to deionized water in a polypropylene tube and subsequently flushed with argon gas. Thirty rapid freezing (30 s in a liquid nitrogen bath) and heating (20 min in an oil bath at 60 °C) cycles were then carried out. The reaction product was obtained in a yield in excess of 60 wt.-%, which indicates that the method can be utilized on an industrial scale for the production of 2D nanosheets. The as-synthesized products were then characterized by TEM, which revealed nanosheet-like morphologies. Raman spectroscopy confirmed the high quality of the nanosheet samples. The exfoliated samples also showed good electrochemical performance. Of the TMDC samples investigated, the WSe2 nanosheets were found to give the best performance due to their uniform morphology, large surface area, and fewest number of defects.

Summary The study of environmental samples requires a preservation system that stabilizes the sample structure, including cells and biomolecules. To address this fundamental issue, we tested the cell alive system (CAS)-freezing technique for subseafloor sediment core samples. In the CAS-freezing technique, an alternating magnetic field is applied during the freezing process to produce vibration of water molecules and achieve a stable, super-cooled liquid phase. Upon further cooling, the temperature decreases further, achieving a uniform freezing of sample with minimal ice crystal formation. In this study, samples were preserved using the CAS and conventional freezing techniques at 4, −20, −80 and −196 (liquid nitrogen) °C. After 6 months of storage, microbial cell counts by conventional freezing significantly decreased (down to 10.7% of initial), whereas that by CAS-freezing resulted in minimal. When Escherichia coli cells were tested under the same freezing conditions and storage for 2.5 months, CAS-frozen E. coli cells showed higher viability than the other conditions. In addition, an alternating magnetic field does not impact on the direction of remanent magnetization in sediment core samples, although slight partial demagnetization in intensity due to freezing was observed. Consequently, our data indicate that the CAS technique is highly useful for the preservation of environmental samples.

Microwave resonator measurements were performed on high-performance microwave ceramics Ba(Zn1/3Ta2/3)O3 (BZT) and Ba(Zn1/3Nb2/3)O3 (BZN) containing additives commonly used by commercial manufacturers (i.e., Co, Mn, and Ni). We find that the loss tangent, even in ambient magnetic fields, is dominated by electron paramagnetic resonance (EPR) absorption by exchange-coupled 3d electrons in transition metal clusters at cryogenic temperatures. The large orbital angular momentum in Co2+ and Ni2+ ions of L = 3 causes strong anisotropic-broadened dipolar interactions that extend EPR losses to zero applied field. This effect is greatest in BZN with Co concentrations greater than 0.5 mol%, dominating the losses at liquid nitrogen temperatures (77 K) and below. In samples containing Mn2+ ions with L = 0, the dipolar interactions and associated EPR losses in ambient fields are smaller. We show the magnetic-field-dependent changes in the EPR losses (i.e., tan δ) and magnetic reactive response (i.e., μr) are from the same mechanism, as they follow the Kramers–Kronig relation. Finally, we note that these materials can make ultra-high Q passive microwave devices with externally controlled transfer functions, as the quality factor (Q) of the composition Ba(Co1/15Zn4/15Nb2/3)O3 at 77 K can be tuned from 1 100 to 12 000 at 10 GHz by applying practical magnetic fields.

Controlled rate freezing (CRF) of biopolymer scaffolds may increase reproducibility of microstructure compared to analog processes. Freezing of collagen-glycosaminoglycan (CG) scaffolds by CRF with liquid nitrogen at chamber cooling rates of −80°C, −40°C, −20°C, or −10°C/min, was compared to submersion in 95% ethanol at −55°C. Cooling rates of −80°C/min or −40°C/min generated scaffolds with pore areas and pore fractions that were comparable to scaffolds frozen in ethanol. Test and control scaffolds were populated with human dermal fibroblasts and keratinocytes to generate engineered skin substitutes (ESS), and evaluated for surface hydration and mitochondrial metabolism. ESS with scaffolds frozen by CRF at −80°C/min or −40°C/min were comparable to, or better than ESS with control scaffolds (p

Background Adding dimethyl sulfoxide (DMSO) to hematopoietic progenitor cells (HPCs) causes an exothermic reaction, potentially affecting their viability. The freezing method might also influence this. The aim was to investigate the effect of 1) precooling of DMSO and plasma (D/P) and white blood cell (WBC)-enriched product, 2) DMSO concentration of D/P, 3) freezing program, and 4) storage method on WBC quality. Study Design and Methods WBC-enriched product without CD34+ cells was used instead of HPCs. This was divided into six or eight portions. D/P (20 or 50%; precooled or room temperature [RT]) was added to the WBC-enriched product (precooled or RT), resulting in 10% DMSO, while monitoring temperature. The product was frozen using controlled-rate freezing (“fast-rate” or “slow-rate”) and placed in vapor-phase or liquid nitrogen. After thawing, WBC recovery and viability were determined. Results Temperature increased most for precooled D/P to precooled WBC-enriched product, without influence of 20 or 50% D/P, but remained for all variations below 30°C. WBC recovery for both freezing programs was more than 95%. Recovery of WBC viability was higher for slow-rate freezing compared to fast-rate freezing (74% vs. 61%; p

In this study, size-exclusion chromatography and high-resolution atomic absorption spectrometry methods have been developed and evaluated to test the stability of proteins during sample pretreatment. This especially includes different storage conditions but also adsorption before or even during the chromatographic process. For the development of the size exclusion method, a Biosep S3000 5 μm column was used for investigating a series of representative model proteins, namely bovine serum albumin, ovalbumin, monoclonal immunoglobulin G antibody, and myoglobin. Ambient temperature storage was found to be harmful to all model proteins, whereas short-term storage up to 14 days could be done in an ordinary refrigerator. Freezing the protein solutions was always complicated and had to be evaluated for each protein in the corresponding solvent. To keep the proteins in their native state a gentle freezing temperature should be chosen, hence liquid nitrogen should be avoided. Furthermore, a high-resolution continuum source atomic absorption spectrometry method was developed to observe the adsorption of proteins on container material and chromatographic columns. Adsorption to any container led to a sample loss and lowered the recovery rates. During the pretreatment and high-performance size-exclusion chromatography, adsorption caused sample losses of up to 33%.

Background An optimal cooling rate is critical for cryopreserving cord blood stem cells, so it is generally achieved by using controlled-rate freezers (CRFs). The cooling rate can be interrupted by many factors during cooling; therefore, a proper response to the interruption in cryopreservation is crucial to prevent the loss of valuable cells. Study Design and Methods Cord blood samples (n = 6) containing 10% dimethyl sulfoxide were cooled from 4 to −80°C using a CRF. At different temperatures during cooling, cells were transferred either to liquid nitrogen vapor phase (LNVP) directly or a −80°C mechanical freezer where they were stored for 18.1 ± 0.6 hours before transferring to LNVP. The cells were stored in LNVP for 127 ± 48.1 hours before postthaw recovery, viability, and survival of total nucleated cells and/or CD45+ cells, CD34+ cells, and colony-forming unit–granulocyte-macrophage (CFU-GM) were assessed. Results For all types of postthaw evaluations, there were no significant differences when cells were transferred to a −80°C freezer before LNVP, regardless of the temperature at which cooling was interrupted. In contrast, there were significant differences when cells were transferred to LNVP directly, but the differences were determined by the type of assays and how viability was calculated. Conclusions Cord blood samples can be transferred to a −80°C freezer anytime during controlled-rate cooling, but should only be transferred to LNVP when the samples have been cooled to −40°C or lower. Percent postthaw survival of CFU-GM should be routinely assessed when controlled-rate cooling is interrupted.

The CdTe thin and thick films were obtained by the close spaced vacuum sublimation technique on a glass substrate under the following growth conditions: the evaporator temperature was 620 °C; and the substrate temperature was varied in the range from 250 °C to 550 °C. High purity CdTe powder was used as a charge for evaporation. The Raman spectra were measured using TRIAX 320 and TRIAX 550 spectrometers at room temperature. The 488-nm line and 514.5-nm line of an Ar+ laser and a 785-nm diode laser were used as excitation sources. The signal was collected by the liquid nitrogen cooled charge-coupled-device (CCD) detector. A number of intense Raman peaks at 140, 167, 190, 271, 332 and 493 cm-1 were observed and were interpreted as TO (140 cm-1), 1LO (167 cm-1), 2LO (332 cm-1), 3LO (493 cm-1) phonon modes and plasmon-phonon mode (190 cm-1). The presence of several phonon replicas in the Raman spectra confirms high crystal quality of the samples. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)