Liquid Nitrogen

Several critical variables associated with successful cryopreservation of oyster embryos (Crassostrea gigas) were examined. These were 1) embryo developmental stage, 2) kind and concentration of cryoprotectant, 3) equilibration time, and 4) freezing rate. The percentage of survival was scored as the number of recovered embryos that swam actively 12 h after thawing and had developed into veliger stage. The oyster

The results of investigation of the spectral characteristics of radiation in the presence of the photonic flame effect recently discovered experimentally are presented. Radiation from a ruby laser operating in the Q-factor modulation regime with a generation wavelength of 694.3 nm is focused near the oriented surface of a globular photon crystal (artificial opal with a globule size of 230 nm) placed on a copper cold guide whose temperature is close to the liquid-nitrogen boiling point (77 K). The spectrum of long-term afterglow (with a duration of about several seconds when the duration of a pump pulse is equal to 20 ns) appearing in the photonic flame effect is detected using a fiber optic minispectrometer and consists of several comparatively narrow lines whose intensity strongly varies with the pumping power. A similar glow is observed in opal samples filled with acetone or ethanol.

Limited recovery of islets post-cryopreservation influences graft survival and transplantation efficiency during diabetes treatment. As curcumin, a potent antioxidant/radical scavenging compound, protects islets against beta cell toxins, we hypothesized that inclusion of curcumin during cryopreservation or during post-thaw culture or both may rescue islets from cryoinjury. To test the effect of curcumin inclusion on islet recovery murine islets were isolated by the collagenase digestion, cultured for 48 h, cryopreserved using dimethylsulphoxide as cryoprotectantwith or without curcumin (10 μM)and then slow cooled to −40°C before immersing them in liquid nitrogen for 7 days. Following rapid thawing with sucrose gradient and 24 h post-thaw culturein presence or absence of curcumin (10 μM)islet viability and functionality were determined. Islet recovery in curcumin treated groups was significantly higher than in groups where islets were cryopreserved without curcumin. Islets cryopreserved with curcumin also showed more intact islets as well as better morphology as compared to islets cryopreserved without curcumin. Curcumin treated islets also showed significant inhibition of ROS generation as compared to islets cryopreserved without curcumin. Glucose responsiveness and insulin secretion in islets cryopreserved with curcumin was equal to that of the freshly isolated islets as against islets cryopreserved without curcumin. Elevated level of Hsp 70 and HO-1 were observed in islets cryopreserved with curcumin and may contribute to curcumin-induced islet rescue. Hence, we conclude that inclusion of curcumin into cryopreservation medium inhibits ROS generation and corresponding islet damage and dysfunction.

This paper presents a voltage sag compensator, which uses a flywheel energy storage system with superconducting magnetic axial thrust bearing (SMB) and a permanent magnet radial bearing (PMB). The SMB was built with Nd-Fe-B magnet and YBCO superconducting blocks, refrigerated with liquid Nitrogen. The magnets are assembled with magnetic flux shapers in order to increase the levitation force and the stiffness. The radial PMB is used to positioning the vertically arranged switched reluctance machine (SRM) used as motor/generator. Simulations of the power electronics and SRM show that the system can work up to 30,000 rpm supplying the required energy during disturbances.

Mono Lake is a closed-basin, alkaline, hypersaline lake located at the western edge of the Great Basin in eastern California. We studied the distribution of arsenic (As) species in the water column of Mono Lake between February and November, 2002. This period captured the seasonal progression from winter mixing, through summer thermal stratification, to autumn overturn. Arsenic speciation was determined by ion chromatography-inductively coupled-plasma-mass spectrometry of samples preserved in the field by flashfreezing in liquid nitrogen. We found that arsenic speciation was dominated (Ͼ90%) by arsenate when oxygen was detectable. Once levels fell below 6 mol/L O 2 , arsenic speciation shifted to dominance by reduced species. Arsenate and arsenite co-occurred in a transition zone immediately below the base of the oxycline and low but significant concentrations of arsenate were occasionally detected in sulfidic hypolimnion samples. Thio-arsenic species were the dominant form of As found in sulfidic waters. Maxima of thio-arsenic species with stoichiometries consistent with mono-, di-and trithio-arsenic occurred in succession as sulfide concentration increased. A compound with a stoichiometry consistent with trithio-arsenic was the dominant As species (ϳ50% of total As) in high sulfide (2 mmol/L) bottom water. Lower concentrations of total As in bottom water relative to surface water suggest precipitation of As/S mineral phases in response to sulfide accumulation during prolonged anoxia.

catalysts characterized by a wide copper content (0.25 < Cu wt% < 9.0) has been discussed. X-ray absorption near edge spectroscopy, electron spin resonance, and near infrared diffuse reflectance spectroscopy (NIR DRS) techniques and IR spectroscopy of adsorbed NO and CO, have been used to demonstrate that the key mechanism of the oxychlorination reaction is the reduction of CuCl 2 to CuCl following the path 2CuCl 2 + C 2 H 4 → C 2 H 4 Cl 2 + 2CuCl. This reaction holds for the cupric ions in the supported amorphous CuCl 2 phase, with its activity enhanced by a very high degree of dispersion as demonstrated by chemisorption measurements (up to 72%). In contrast Cu(II) cations forming the surface copper aluminate phase are unreactive toward ethylene. A detailed analysis of the IR spectra obtained at liquid nitrogen temperature allows extraction of important information on catalyst support: (i) Cl − anions are hosted on the support surface and their presence enhances the Brønsted acidity of the surface >Al-OH groups; and (ii) >Al 3+ coordinative unsaturated Lewis acidic sites are present on the catalyst. These results point out the possible determinant role of the support in side reactions and coking that are responsible for loss of selectivity and, respectively, catalyst decay during industrial runs.

Beef and beef fat control composites (CC) were prepared for a large multi-year study of conjugated linoleic acid (CLA) and trans-vaccenic acid (TVA) in beef. Raw ground beef and beef suet were each frozen in liquid nitrogen, ground to a fine powder, dispensed into subsamples, and stored at − 60°C under nitrogen. The CCs, reference materials (beef/pork fat; meat homogenate), and standards prepared at two concentrations of CLA and TVA added to a total lipid extract of beef (differing by 0.27 g/100 g CLA and 1.2432 g/100 g TVA) were analyzed via alkaline saponification of lipids, derivatization to fatty acid methyl esters, and GC. CLA and TVA recoveries from the standards were 95-113% (CLA) and 103-106% (TVA). Fatty acids quantified in the reference materials were within the certified ranges. Relative standard deviations (n = 3 in each of 5 assay batches) were b 5% (TVA) and b 10% (CLA) for both CCs, at both laboratories.

The effects of cryogenic cooling on cutting forces in the milling process of AISI 304 stainless steel were investigated experimentally. Cryogenic cooling was achieved by spraying liquid nitrogen to tool, chips and material interfaces using a pipe with an internal diameter of 1 mm; the flow rate of liquid nitrogen was 5.2 L/min; two cutting directions (climbing and conventional milling), two machining conditions (dry and cryogenic cooling) and four cutting speeds (80, 120, 160 and 200 m/min) were used in the milling process. Cryogenic cooling and cutting speed are found to be effective on cutting forces. Cutting forces and torque in cryogenic milling are higher than those in dry milling. Cutting force is increased as the cutting speed is increased. Tool fritter around insert nose radius is the main problem of climb milling method in cryogenic cooling at low cutting speeds.

By internal oxidation of AgMg- and PdMg-alloys small precipitates ofMgO are formed within the Ag- or Pd-matrix. Thetotal area of the metal/oxide interface produced this way becomes severalsquare meters in one cubic centimeter of metal. Segregation of oxygen at theinterface is determined by desorption of gaseous oxygen for theAg/MgO-interface and by trapping of hydrogen for the Pd/MgO-interface. At673 to 873

Current generation high-temperature superconducting (HTS) power transmission cables use liquid nitrogen as a coolant that circulates along the cable. In this work, the use of axial conduction-cooling in attaining HTS temperatures in transmission lines is proposed. Liquid coolant use is envisioned only at periodic length intervals along the transmission lines, in combination with insulation and copper. The proposed concept is feasible due to the high thermal conductivity of pure copper at cryogenic temperatures. A basic design for the insulated cable is proposed and a detailed numerical simulation of heat transfer in such a cable is carried out for various case studies considering the superconducting materials MgB 2 and BSCCO-2223.

The objective was to compare the use of powdered coconut water (ACP-109c; ACP Biotecnologia, Fortaleza, CE, Brazil) and Tris extenders for recovery and cryopreservation of epididymal sperm from agouti. The caudae epididymus and proximal ductus deferens from 10 sexually mature agoutis were subjected to retrograde washing using ACP-109c (ACP Biotecnologia) or Tris. Epididymal sperm were evaluated for motility, vigor, sperm viability, membrane integrity, and morphology. Samples were centrifuged, and extended in the same diluents plus egg yolk (20%) and glycerol (6%), frozen in liquid nitrogen, and subsequently thawed at 37°C for 1 min, followed by re-evaluation of sperm characteristics. The two extenders were similarly efficient for epididymal recovery, with regard to the number and quality of sperm recovered. However, for both extenders, sperm quality decreased (P Ͻ 0.05) after centrifugation and dilution. After sperm cryopreservation and thawing, there were (mean Ϯ SEM) 26.5 Ϯ 2.6% motile sperm with 2.6 Ϯ 0.2 vigor in the ACP-109c (ACP Biotecnologia) group, which was significantly better than 9.7 Ϯ 2.6% motile sperm with 1.2 Ϯ 0.3 vigor in Tris. In conclusion, agouti epididymal sperm were successfully recovered using either ACP-109c (ACP Biotecnologia) or Tris extenders; however, ACP-109c (ACP Biotecnologia) was a significantly better extender for processing and cryopreserving these sperm.

Over the past years, there have been a number of serious explosions in air industry, which have resulted in workers injuries and fatalities. At the same time, there has been an increase in the use of air separation products for industrial activities.

In this paper we report a simple tuning methodology of high temperature superconducting (HTS) microstrip filters. In order to establish this new tuning approach a 5 pole lumped element HTS bandpass filter, centre frequency 800 MHz, narrowband (bandwidth, 7.6 MHz), is designed and fabricated on a 2 inch (diameter) YBa 2 Cu 3 O 6.94 thin film of thickness 700 nm and lanthanum aluminate (LaAlO 3 ) substrate of 0.5 mm thickness. The filter was etched using conventional photolithography and a wet chemical etching process. The 5 pole lumped element filter is tested in an integrated RF-cryocooler measurement system at 65 K and also in liquid nitrogen (77 K). We demonstrate a 19.3 MHz downward shift of the centre frequency of the 5 pole filter response. This is achieved by overlaying two layers of thin dielectric tape (PTFE) (50.0 µm thickness, permittivity 3.2) over the conducting patterned part of the filter surface. A full wave electromagnetic analysis of the dielectric environment of this tuning arrangement matches the measured response closely. To improve the passband response, the filter is tuned in liquid nitrogen, placing pieces of sapphire rods over the resonators of the filter layout.

To remove the environmental and safety hazards associated with power transformers, the authors have investigated the use of liquid nitrogen as a replacement for transformer oil. This paper details tests performed to determine new design rules and efficiency expectations of liquid nitrogen filled power transformers (Enviro-Transformers). The tests include dielectric strength testing of liquid nitrogen and mechanical strength testing of

Objective: To evaluate long-term outcome of autotransplantation of cryopreserved hemi-ovaries into ewes. Design: Animal study. Setting: University fertility center, Hospices Civils de Lyon; and Ecole Nationale Vétérinaire de Lyon. Patients(s): Grivette ewes. Intervention(s): Six hemi-ovaries from 6 ewes aged 6 to 12 months were frozen with a slow cooling protocol using 2 M of dimethyl sulfoxide as cryoprotectant. After dissection of the medulla, the hemi-ovarian cortex was stored at Ϫ196°C in liquid nitrogen. Freezing procedure was performed with a programmable freezer. Semiautomatic seeding was performed before crystallization. Four to 6 weeks after the first laparotomy, the left ovary was removed and the frozen-thawed hemi-ovary was sutured. Main Outcome Measure(s): Mean plasma concentrations of FSH, LH, and progesterone after autotransplantation of frozen-thawed hemi-ovary. Ultrasonography was done to confirm pregnancy. Blood samples were collected weekly to measure FSH, LH, and progesterone. After the first birth, the autografted ovary was removed for histologic examination. Result(s): Plasma progesterone concentration increased in a regular manner in all ewes except one 4 weeks after the graft. Concentrations of FSH and LH did not reach the menopausal level. Four pregnancies occurred, from which 6 lambs were born. The first delivery of a normal lamb occurred after 135 days of gestation; the lamb died immediately after birth. The second delivery of two normal lambs occurred after 130 days of gestation. A caesarean section was performed on the third pregnant ewe the 110th days of gestation because the ewe had a vaginal prolapsus. The two normal lambs and the ewe died after surgery. The fourth birth of a normal lamb occurred after 132 days of gestation. Histologic examination of the grafted frozen-thawed ovary showed a regressing corpus luteum and few primordial and antral follicles. Conclusion(s): These four pregnancies in a ewe model may indicate that women who undergo preservation of their ovaries before chemotherapy or radiotherapy can have successful pregnancy. (Fertil Steril 2002;77: 403-8.

Egg yolk is one of the most widely used cryoprotective components for sperm preservation and a wide range of factors affect its action on sperm motility, viability and fertilizing ability. The aim of this experiment was to determine the effect of different species egg yolk, namely the domestic chicken (Gallus gallus domesticus), the goose (Anatidae anser), turkey (Meleagris gallopavo), duck (Anatidae anas platyrhynchos), Japanase quail (Coturmix japonica) and chucker (Alectoris chukar) on sperm quality following cryopreservation of ram semen. Ejaculates were collected using the artificial vagina from three Karayaka rams and spermatological characteristics assessed for the pooled semen. Semen samples were evaluated as split ejaculates in the trial and samples extended with a Tris-citric acid-glucose extender containing the different avian egg yolk (15%) and glycerol (5%). The semen straws were equilibrated at 4 • C for 2 h, frozen in liquid nitrogen vapour (for 15 min at −120 • C) and stored in liquid nitrogen (−196 • C). After thawing (37 • C for 30 s), sperm motility, viability, abnormal acrosome and membrane integrity (HOST) were evaluated. Results showed chucker egg yolk to have the best cryoprotective effect in terms of the highest sperm motility (54.0%), compared to the other five avian egg yolks (p < 0.05) evaluated. Sperm frozen in chucker egg yolk also showed a higher percentage viability (59%), than sperm stored in quail and turkey egg yolk (p < 0.05). The percentage of acrosomal abnormalities after thawing was lower in the chucker egg yolk, than the other species (p < 0.05). There was no significant difference in sperm membrane integrity between the egg yolks, except for the quail (p < 0.05). Results suggest that chucker egg yolk could be used as an alternative for chicken egg yolk, in a semen extender in cryopreservation, but it warrants further evaluation in fertility trials.

FullereneC 60 thin films on glass substrate (around 2000 thickness) were prepared by thermal evaporation technique. The structural, Surface morphology and optical properties of the film were studied. Optical properties in the spectral range 200 nm to 900 nm of Fullerene C 60 film is investigated by spectrophotometer at different temperature i.e.; room temperature and liquid nitrogen temperature (77K). Optical band gap at room temperature is found to be 2.30 eV, which goes on decreasing and reaches to 2.27 at 77K. Result indicates that C 60 film become more conducting at low temperature. Thickness and refractive index of film was calculated by ellipsometry. From the X ray analysis we have calculated the grain size, dislocation density, number of crystallite per unit area, and strain of the film. The surface morphology of film was analyzed by scanning electron microscope (SEM).

The principal resolution limitation in electron cryomicroscopy of frozen-hydrated biological samples is radiation damage. It has long been hoped that cooling such samples to just a few kelvins with liquid helium would slow this damage and allow statistically better-deWned images to be recorded. A new "G2 Polara" microscope from FEI Company was used to image various biological samples cooled by either liquid nitrogen or liquid helium to »82 or »12 K, respectively, and the results were compared with particular interest in the doses (10-200 e ¡ /Å 2 ) and resolutions (3-8 nm) typical for electron cryotomography. Simple dose series revealed a gradual loss of contrast at »12 K through the Wrst several tens of e ¡ /Å 2 , after which small bubbles appeared. Single particle reconstructions from each image in a dose series showed no diVerence in the preservation of medium-resolution (3-5 nm) structural detail at the two temperatures. Tomographic reconstructions produced with total doses between 10 and 350 e ¡ /Å 2 showed better results at »82 K than »12 K for every dose tested. Thus disappointingly, cooling with liquid helium is actually disadvantageous for cryotomography. 

Herbal and aromatic plants are attracting more attention among contemporary plant researchers because some human diseases resulting from bacterial antibiotic resistances have gained worldwide concern. A number of methods are available and are being developed for the isolation of nucleic acids from plants. Because plants contain high amounts of many different substances, it is unlikely that just one nucleic acid isolation method suitable for all plants can ever exist. Therefore, we developed 4 modified new methods that produced good quality DNA from these plants. This article deals with modern approaches in determining genetic variability, in which three categories of genetic markers are applied by morphological, biochemical and molecular. Furthermore, the aim is to assess the available genetic diversity for each species; to provide more accurate and detailed information than is available using classical phenotypic data in this subject. Various types of plant materials and a number of different protocols for the isolation of DNA were tested in order to obtain good quality DNA for PCR reactions. Ten populations of different aromatic and medicinal plants from Turkey were tested in the study. The number of plants examined for each population varied from two to five. When fresh or frozen leaves of plants collected in autumn were used for the isolation of DNA, no positive result in PCR reaction was obtained regardless of the isolation protocol being used. Four different DNA methods were compared for the isolation of DNA from the different plant homogenates, namely the CTAB, Plant Genomic DNA Purification Kit, and EZ1 Nucleic acid isolation methods and DNA extraction with phenol purification and liquid nitrogen method.

The stability of phenolic compounds of three strawberry cultivars was evaluated for changes during prefreezing treatments, storage and various freezing and thawing conditions. Polyphenol content was determined by HPLC-DAD-FL. The sum of assayed polyphenolic (proanthocyanidin and monomeric flavan-3-ols, anthocyanins, ellagic acid, p-coumaric acid) represented 2858.4 mg/kg in Kent, 2893.1 mg/ kg in Elkat, and 2438.0 mg/kg in Senga Sengana. After freezing, 4.5-33.6% of polyphenols were lost; protective effects of prefreezing treatments were seen on anthocyanidins and proanthocyanidins: ascorbic acid was the most effective pretreatment, allowing retention of 3.9-27.5% of anthocyanins, and almost total recovery (3.9-23.9%) when associated with liquid nitrogen freezing. Pectin and sugar only allowed retention of 3.0-25.1% and 5.5-25.4% of the antocyanins, respectively. Thawing of the strawberries in a microwave oven (instead of 20 h at 20 C) had a further positive effect on retention of anthocyanins, proanthocyanins, (þ)-catechin and ellagic acid.

Pre-fermentation cold maceration of must by the direct addition of two cryogens was studied. The experiments were conducted on Sangiovese grape from a typical Chianti vineyard in the year 2001 with two cryogens (solid state carbon dioxide and liquid nitrogen) and at various temperatures (from 5 to +5 C) in 500-L batches for 48 h. The wines obtained were characterized by chemical analyses and sensory evaluation, and higher quality resulted as seen from the analytical and sensory characteristics with higher extraction of polyphenolic compounds at lower cold maceration temperature. Liquid nitrogen was more effective than solid carbon dioxide at the same temperature. Proportional increase of wine quality with lower cold maceration temperature was observed for solid carbon dioxide. Further investigation is needed to establish the management protocol, a proper engineering of this technique, and to evaluate its economical advantages.

For environmental considerations, the substitution of the conventionally used oil-based grinding fluids has nowadays become strongly recommended. Although several alternatives have been proposed, cryogenic cooling by liquid nitrogen is the non-polluting coolant that has been given relatively more attention because of its very low temperature. In this investigation, in order to contribute to developing this promising cooling mode, its beneficial effects on the ground surface integrity of the AISI 304 stainless steel and their consequences on the fatigue lifetime are explored. Results of this investigation show that grinding under cryogenic cooling mode generates surfaces with lower roughness, less defects, higher work hardening and less tensile residual stresses than those obtained on surfaces ground under oilbased grinding fluid. These surface enhancements result into substantial improvements in the fatigue behaviour of components ground under this cooling mode. An increasing rate of almost 15% of the endurance limit at 2 · 10 6 cycles could be realized. SEM analyses of the fatigue fracture surfaces have shown that the fatigue cracks observed on the specimens ground under cryogenic cooling are shorter (i.e., 30-50 lm) than those generated under oil-based cooling mode (i.e., 150-200 lm). The realized improvements in the surface integrity and in the fatigue behaviour are thought to be related to the reduction of the grinding zone temperature observed under cryogenic cooling, as no significant differences between the grinding force components for both cooling modes have been observed.

Pollination effectiveness was evaluated for pollen (pollinia) from two Dendrobium hybrids, ‘Sena Red’ and ‘Mini WRL’, submitted to cryopreservation using a vitrification protocol. Parameters evaluated included pollinia exposure to a previtrification solution (PVS2) under ice (0 °C) or room (27 ± 2 °C) temperatures from 1 to 4 hours before cryopreservation (LN). On removal from cryopreservation, pollinia were used to pollinate flowers of the same hybrids to verify viability and germination. All pollinia showed high percentages of germination (greater than 80%) after crosses were performed, except for pollinia from Dendrobium ‘Sena Red’ submitted to 3 hours of precooling (0 °C) in PVS2 followed by LN (60%) and for pollinia submitted to PVS2 for 3 hours at room temperature with no precooling (70%). Capsules were formed for both hybrids and seeds were successfully produced. The seed viability test revealed high viability (90% to 95%) for all treatments for both hybrids. Seeds observed u...

We have studied two samples of synthetic sapphire. Sample 1 was used as a window in a cryostat and was subjected to liquid nitrogen temperature for a long time (two years). Sample 2 was stored at room temperature. Under identical conditions, three types of Raman spectra were measured on Sample 1 in the wave number range 100–800cm−1. In the spectra

We have optimized a simple and rapid method for isolating milligram quantities of high quality DNA from polysaccharide- and polyphenolic-rich tissue such as sugarcane, lettuce and strawberry. The protocol utilizes fresh tissue without making use of liquid nitrogen or freeze-drying for initial grinding of the tissue and it significantly minimize the use of lab materials. At least one hundred samples can be processed daily by one person. The isolated DNA is essentially free of polysaccharides, polyphenols, RNA and other major contaminants, as judged by: its clear color, its viscosity, A260/A280 ratio, digestibility with restriction enzymes, and suitability for Restriction Fragment Length Polymorphism (RFLP)- and Polymerase Chain Reaction (PCR)-based techniques.

The present work was aimed to study the effect of various grinding agents and detergents on the amount and purity of
the extracted DNA from diverse plant samples. Agents supporting grinding process were liquid nitrogen, acid washed
sand and glass beads, along with a number of concentrations of two detergents i.e. SDS (Sodium Dodecyl Sulphate)
and CTAB (Cetyltrimethylammonium bromide). Six plants species Croton (Codiaeum variegatum), Tomato
(Lycopersicon esculentum), Orchid (Orchis militaris), Date palm (Phoenix dactylifera L.), Pineapple (Ananas
cosmosus) and Aloe (Aloe vera); were selected for DNA isolation and these plant species differ in their leaf texture as
well as polysaccharides and phenolics content. The results obtained showed the presence of linear relationship between
detergent and yield of the DNA with a little influence on the purity. The type of grinding agent did not significantly
affect the purity of the extracted DNA but the amount of extracted DNA is greatly influenced. The purest DNA samples
of all six plants species were selected and subjected to PCR amplification.

The behavior HTS materials and devices at overload currents is determined in a very high level by cooling, particularly, by the transient heat transfer from HTS device to liquid nitrogen. Recently we observed sharp peaks in the voltage during rectangular current pulse. In the present paper we explain these peaks by analysis of transient regimes in liquid nitrogen. The sharp peak in the voltage is occurring after temperature exceeds certain level before nucleate boiling starts. Basing on measurements of the voltage and temperature of HTS tapes during current overload and numerical analysis of the process we estimated overheat temperatures of nitrogen in transient regimes. Influence of covers of HTS tapes on overheat temperature of nitrogen is discussed. Experimental data and theoretical calculations' are compared.

While microspheres have been recognized as a legitimate insulation material for decades, actual use in full-scale cryogenic storage tanks has not been demonstrated until now. The performance and life-cycle-cost advantages previously predicted have now been proven. Most bulk cryogenic storage tanks are insulated with either multilayer insulation (MLI) or perlite. Microsphere insulation, consisting of hollow glass bubbles, combines in a single material the desirable properties that other insulations only have individually. The material has high crush strength, low density, is noncombustible, and performs well in soft vacuum. These properties were proven during recent field testing of two 22,700-L (6,000-gallon) liquid nitrogen tanks, one insulated with microsphere insulation and the other with perlite. Normal evaporation rates (NER) for both tanks were monitored with precision test equipment and insulation levels within the tanks were observed through view ports as an indication of in...

Aerogel based insulation systems for ambient pressure environments were developed for liquid hydrogen (LH2) tank applications. Solutions to thermal insulation problems were demonstrated for the Space Shuttle External Tank (ET) through extensive testing at the Cryogenics Test Laboratory. Demonstration testing was performed using a 1/10th scale ET LH2 intertank unit and liquid helium as the coolant to provide the 20 K cold boundary temperature. Cryopumping tests in the range of 20K were performed using both constant mass and constant pressure methods. Long-duration tests (up to 10 hours) showed that the nitrogen mass taken up inside the intertank is reduced by a factor of nearly three for the aerogel insulated case as compared to the un-insulated (bare metal flight configuration) case. Test results including thermal stabilization, heat transfer effectiveness, and cryopumping confirm that the aerogel system eliminates free liquid nitrogen within the intertank. Physisorption (or adsorption) of liquid nitrogen within the fine pore structure of aerogel materials was also investigated. Results of a mass uptake method show that the sorption ratio (liquid nitrogen to aerogel beads) is about 62 percent by volume. A novel liquid nitrogen production method of testing the liquid nitrogen physical adsorption capacity of aerogel beads was also performed to more closely approximate the actual launch vehicle cooldown and thermal stabilization effects within the aerogel material. The extraordinary insulating effectiveness of the aerogel material shows that cryopumping is not an open-cell mass transport issue but is strictly driven by thermal communication between warm and cold surfaces. The new aerogel insulation technology is useful to solve heat transfer problem areas and to augment existing thermal protection systems on launch vehicles. Examples are given and potential benefits for producing launch systems that are more reliable, robust, reusable, and efficient are outlined.

Edible ®lms are thin materials based on a biopolymer. The objectives of this work were to determine the water vapor permeability and the mechanical and thermal properties of edible ®lms based on bovine hide and pigskin gelatins. These ®lms were prepared with 1 g of gelatin/ 100 ml of water; 15±65 g sorbitol/100 g gelatin; and at natural pH. The samples were conditioned at 58% relative humidity and 228C for 4 days before testing. The mechanical properties were determined by the puncture test and the water vapor permeability by gravimetric method at 228C. For DSC analysis, samples were conditioned over silica gel for 3 weeks. Samples (t10 mg) were heated at 58C/min, between 2150 and 1508C in a DSC TA 2010. A second scan was run after cell cooling with liquid nitrogen. As expected, the puncture force decreased and the puncture deformation and water vapor permeability increased with the sorbitol content. The origin of gelatin was important only above 25 g sorbitol/100 g gelatin. The DSC traces obtained in the ®rst scan of samples with 15±35 g sorbitol/100 g gelatin, showed a well visible glass transition followed by a sol±gel transition. However, with the increase of sorbitol concentration, the glass transition became broader, typical of the system presenting a phase separation. The model of Couchman and Karazs for ternary system, was used to predict the Tg values as a function of sorbitol concentration. q (P.J.A. Sobral).

Multiple size group (MUSIG) model combined with a three-dimensional two-fluid model were employed to predict subcooled boiling flow of liquid nitrogen in a vertical upward tube. Based on the mechanism of boiling heat transfer, some important bubble model parameters were amended to be applicable to the modeling of liquid nitrogen. The distribution of different discrete bubble classes was demonstrated numerically and the distribution patterns of void fraction in the wall-heated tube were analyzed. It was found that the average void fraction increases nonlinearly along the axial direction with wall heat flux and it decreases with inlet mass flow rate and subcooled temperature. The local void fraction exhibited a U-shape distribution in the radial direction. The partition of the wall heat flux along the tube was obtained. The results showed that heat flux consumed on evaporation is the leading part of surface heat transfer at the rear region of subcooled boiling. The turning point in the pressure drop curve reflects the instability of bubbly flow. Good agreement was achieved on the local heat transfer coefficient against experimental measurements, which demonstrated the accuracy of the numerical model.

The USDA-ARS National Clonal Germplasm Repository (NCGR) stores the global diversity of Humulus for the US Plant Germplasm System as trellised plants in a field genebank. In vitro storage and cryopreservation are now considered excellent ways to provide medium and long-term storage for plant collections. Developing a new cryopreservation or cold storage protocol for every accession or genus of large multi-crop collections can be a very time consuming and long-term activity. We propose that standard cold storage and cryopreservation techniques used for other temperate crop genera would be successful for additional crops with few modifications. This study was initiated to determine if a large collection of hops germplasm could be successfully stored with techniques developed for unrelated genera. In this study we characterized the response of diverse Humulus genotypes to in vitro storage under low light at 4 degree C following techniques used for strawberry and mint plants, and cryopr...

The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original docum and are linked to publications on ResearchGate, letting you access and read them immediately. Plant biotechnology, a major component of agricultural biotechnology, deals with various aspects of plant tissue culture, genetic transformation, and molecular biology techniques. Tissue culture methods offer a rich scope for creation, conservation, and utilization of genetic variability for the improvement of field, fruit, vegetable, and forest crops, and medicinal/aromatic plants. Micropropagation technology ensures true to type, rapid and mass multiplication of plants that possesses special significance in vegetatively propagated plant species. This technology has witnessed a huge expansion globally, with an estimated global market of 15 billion US$/annum for tissue-culture products. Some basic techniques of tissue culture, such as anther/microspore culture, somaclonal variation, embryo culture, and somatic hybridization, are being exploited to generate useful genetic variability for obtaining incremental improvement in commercial cultivars. Production of secondary metabolites, such as food flavors, food colors, dyes, perfumes, drugs, and scented oils used in aromatherapy, through cell cultures and hairy root cultures, are leading examples of molecular farming. Cryopreservation of germplasm at the cell/tissue/organ levels, in liquid nitrogen at −196 • C, is highly rewarding for establishing germplasm banks, especially for vegetatively propagated crops and rare, endangered plant species. During the past 15 years, remarkable achievements have been made in the production, characterization, field evaluation, and release of transgenic varieties/hybrids in several crops. Transgenic varieties/hybrids of maize, cotton, soybean, potato, tomato, and papaya are now being commercially grown on about 134 million hectares spread across 25 countries. Research in genomics allows high-resolution genetic analysis for physical mapping and positional gene cloning of useful genes for crop 153 154 S. S. Gosal et al. improvement. Molecular (DNA) markers help in precise characterization of germplasm, construction of saturated linkage maps, and DNA fingerprinting of crop varieties. Molecular markers are now increasingly being used for marker-assisted gene pyramiding and alien gene introgression. Current research, involving large-scale DNA sequencing, microarrays, and robotics, is heading towards gene revolution and nanobiotechnology.