LN2 Tank Research Articles

Effect of pressurant flow rate and ullage conditions on mass transfer and thermal stratification in a partially filled LN2 tank

Experimental and numerical computations have been carried out to investigate the evolution of pressure and temperature in the liquid nitrogen (LN2) tank pressurized with gaseous nitrogen (GN2). A parametric study has been carried out to study the effect of ullage volume and pressurant gas (GN2) flow rate (0.25–2 g/s) and temperature (250–350 K) on the pressure evolution and thermal stratification in the tank during active pressurization from 1 bar to 3 bar. Experiments are conducted in a small range of mass flow rates at a given pressurant gas temperature (302 K). The numerical simulations are validated with the experiments and a parametric study has been performed. It has been observed that pressurization time varies linearly with the liquid depth. Thermally stratified mass in LN2 increases with the decrease in pressurant mass flow rate for a given pressure rise. Numerical simulations revealed that mass condensed during the pressurization is a weak function of ullage depth and temperature but a strong function of the mass flow rate. The pressurant gas requirement follows the correlation of Ludwig and Dreyer (2014) for relatively higher mass flow rates. The pressurant gas temperature has a strong influence on the flow pattern in the ullage. The pressurant gas flows along the wall and reaches the interface without disturbing the bulk vapor. Heat transfer at the interface is dominated by the heat carried by the pressurant than by transfer from the bulk vapor.

Effect of exposed-to-air frequency of cryopreserved embryo on clinical outcomes of vitrified-warmed embryo transfer cycles: a retrospective analysis of 9,200 vitrified-warmed transfer cycles

BackgroundCryopreservation of embryos plays a major role in the in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) treatment. However, the storage condition of the cryopreserved embryo can change temporarily due to repeated retrieval of the embryo from the liquid nitrogen (LN2) tank during the practical application during cryopreservation. Whether the implantation potential of a cryopreserved embryo will be damaged when the cane containing it is temporarily exposed to air due to the transfer between the LN2 tank and LN2 container is yet to be elucidated. Also, whether the exposed-to-air frequency (EAF) of cryopreserved embryos influences the clinical outcomes is unclear.ObjectiveTo investigate whether the EAF of cryopreserved embryo affects the clinical outcomes of vitrified-warmed embryo transfer.MethodsA total of 9200 vitrified-warmed embryo transfer cycles were included in this study. All cycles were divided into five groups according to different EAFs (2, 4, 6, 8, or ≥ 10). Post-warming survival rates and clinical outcomes, including implantation, clinical pregnancy and live birth rates were investigated. Kruskal–Wallis test and Pearson’s chi-squared tests were used to compare the patient characteristics and clinical outcomes among the five groups. Furthermore, multivariate logistic regression analyses were conducted to investigate the association between EAF and clinical outcomes.ResultsNo significant differences were observed in the positive HCG rate, implantation rate and live birth rate (P > 0.05) among five EAF groups with respect to D3 embryo, D5 blastocyst and D6 blastocyst. Post-warmed survival rate of D3 embryos (P = 0.015) differed significantly among the five EAF groups, but it was not EAF-dependent. Although clinical pregnancy was different among the five groups with respect to D5 blastocyst (P = 0.042), multivariate logistic regression analysis adjusted for confounding variables suggested that EAF did not adversely affect clinical pregnancy or live birth.ConclusionThese findings indicated that human vitrified embryos in the open system could be repeatedly retrieved from the LN2 tank without affecting the implantation potential of the embryo.

The dynamic performance of a compact LN2 depressurization cryocooling system

Liquid nitrogen (LN2) has been widely used as a cooling medium. A compact LN2 depressurization cryocooling system can be used as a portable cooling unit to satisfy flexible cooling requirements. A prototype of this cryocooling system which was mainly composed of a LN2 tank, a LN2 pump, a heat exchanger and a vacuum pump was built and tested. In the test, the lowest cooling temperature could reach below 65 K, and the average temperature of 0.95 m3 LN2 dropped from 73.5 K to 68.1 K after 6814 s of running. The average refrigeration power reached 1326 W at 65 K. Meanwhile, the system operation process was simulated through theoretical analysis and modeling. Simulation results were nearly consistent with experimental results and the dynamic operating characteristics were well captured. For the experimental apparatus, the LN2 supplement and shutdown of the liquid-ring pump affect the system cooling performance, and modeling results show that the cooling efficiency decreases with the LN2 volume flow rate V̇LN2 increasing whenV̇LN2 > 0.9 m3/h.

Effects of glucose and trehalose on tris-citric acid-egg yolk-fructose diluents for semen cryopreservation in goat.

This study aimed to examine the impacts of the wide range of concentrations of glucose and trehalose on the tris-citric acid-egg yolk-fructose (TCEF) extenders for cryopreservation of goat semen. The sperm sample was pooled, washed, and diluted in control (TCEF without glucose and trehalose), TCEF + glucose (75, 150, 450, and 900 mm), and TCEF + trehalose (75, 150, 450, and 900 mm). After equilibrations, the semen straws were frozen under LN2 in the LN2 tank. After LN2 storage, the straws were thawed at 37°C for 30 seconds. The sperm parameters of all study groups were checked after equilibration and freezing. After equilibration, the progressive motility (PM), total motility (TM), and viability of sperm in G-75, G-150, G-450, T-75, T-150, and T-450 were not significantly different (p < 0.05) from those in control. After cryopreservation and thawing, the PM, TM, and plasma membrane integrity (PMI) of T-150 were significantly higher (p < 0.05) than in control, G-75, G-900, T-75, and T-900. The viability of sperm in T-150 was substantially higher (p < 0.05) than in the control, whereas there was no significant difference among the control, G-75, G-900, T-75, and T-900. However, the acrosome integrity (AI) of sperm in G-900 was significantly decreased (p < 0.05) compared to the control, G-75, G-150, G-450, T-75, T-150, and T-450. According to the findings, the supplementation of 150 mm trehalose in the TCEF diluent was more efficient for sperm cryopreservation in the buck as reflected by PM, TM, viability, PMI, and AI.

Frozen Semen Quality of Kolbroek Boars Concerning Glutathione Concentrations

Glutathione(GSH) is an antioxidant that is being studied for its ability to improvecellular responses to semen preservation challenges. The research goal aimed toevaluate the impact of introducing different glutathioneconcentrations to boar semen freezing extender (0, 1, 5, and 10 mM) onthe Kolbroek boar sperm's quality after being frozen and thawed. For 2 h, thecollected sperm-rich fraction was chilled at 17°C. Following the 1 h ofequilibration, fraction B: Control (egg yolk 20% + BTS 72% + glycerol 8%), 1 mM(egg yolk 20% + BTS 70% + glycerol 8% + GSH 2%), 5 mM (egg yolk 20% + BTS 62 + 8%glycerol + GSH 10%) and 10 mM (egg yolk 20% + BTS 52% + glycerol 8% + GSH 20%)was added into the semen samples. Following that, 0.5 mL straws with thediluted, cooled semen samples were submerged in liquid nitrogen (LN2)vapor and then stored inside the LN2 tank (-196°C). After thawing(37°C), parameters of boar sperm motility, velocity, morphology and viability,membrane permeability, and Malondialdehyde content were assessed and recorded.Using the analysis of variance, the data were examined. The results revealed adifference in total motility (%) on fresh semen as compared to post-thawedcontrol and GSH treatments. A significant difference was revealed in spermprogressive motility (%) in fresh semen (27.07±4.5). Significant differenceswere recorded in live sperm morphology and viability on fresh semen (81.8±2.8%)compared to control, 1, 5, and 10 mM. In the10 mM diluted semen (78.5±6.8), the proportion of sperm with an intact plasmamembrane integrity was highest (P<0.05), while the percentage in the1 mM diluted semen (73.0±2.7) was lower. Malondialdehyde levels were lowest (P<0.05)in the group receiving 5 mM treatment. In conclusion, 5 mM of GSH is therequired amount to be added to the freezing extender while cryopreserving semenfrom Kolbroek boars.

Comparison of Temperature Equilibrium Rate and Cell Growth/Viability Under Air Circulation in Cryogenic Storage Container

Abstract With advances in biotechnology, the field of cryopreservation has been continuously developed and improved. Typical cryo-container was designed with minimal flow to avoid possible structural defects in LN2 tank, which has a higher thermal conductivity than vapor nitrogen tank. If cells are placed in typical cryo-container and stored in VN2 tank, cross-contamination can be prevented, but the cell viability after thawing may be reduced. The structure of typical cryo-containers is not optimized for vaporized nitrogen to flow quickly into the container and its circulation well. Therefore, we proposed new cryo-container models that can maintain mechanical strength while optimizing the fluid flow structure, and performed thermal–structural coupled field analysis on cryo-containers. We confirmed the cryo-containers by comparing the equivalent stress distributions formed around through holes and evaluating thermal equilibrium in the cryogenic steady-state through flow analysis. Prototype cryo-containers and typical cryo-containers were placed in VN2 tank for a period of time to observe temperature changes. As a result, the time it takes to reach the temperature equilibrium has been reduced to 55% level compared with the typical cryo-containers. Additionally, C2C12 and hADMSC cells were checked after storage under two temperature conditions (−80 and −196 °C). In both cell, viability, adhesion, and relative cell proliferation were improved by up to 15–20% in new containers compared to typical products. The developed container is expected to maintain stability well by being applied to storage and transportation of advanced medicines that require cryopreservation.

Preliminary design of a helium cryogenic system for SAND detector at LBNF-DUNE near site

The Long-Baseline Neutrino Facility (LBNF) is providing a helium cryogenic system to support the superconducting solenoid magnet of the System for on-Axis Neutrino Detection (SAND) for the Deep Underground Neutrino Experiment (DUNE) Near Site at Fermilab in Batavia, IL. The design started in 2020 and construction is set to begin in the mid 2020‘s.The helium cryogenic system primarily consists of a helium refrigerator system, distribution valve boxes, vacuum-jacketed helium and nitrogen transfer lines, warm gaseous helium transfer system, instruments and control system, and gaseous helium storage tanks. It is designed to provide supercritical helium at around 3 bara and 5 K with expansion from 3 to 1.2 bara in the SAND cryostat and 70K forced cold gas helium to cool the thermal shields of the SAND cryostat. The SAND superconductive magnet is indirectly cooled through a liquid helium thermosiphon cycle. A pair of 3 kA leads is cooled by the gas helium vaporized from the liquid helium reservoir in the cryostat turret. The helium system will share the liquid nitrogen tank and liquid nitrogen phase separator with the Near Site Liquid Argon system. The helium recycle compressor system, GHe tanks and LN2 tank will be located on the Surface. The cryogenic facilities including refrigerator cold box, valve boxes and LN2 phase separator will be located on the shaft cryo-mezzanine in the underground cavern. The shaft connecting surface and cavern is more than 60 meter deep. The helium vacuum-jacketed transfer line between the cold box and the SAND magnet is more than 50 meter long. This paper presents the preliminary design of the helium cryogenic system including the design scheme, process flow diagram, heat load estimates, layout plan and so on.

Analysis of a newly developed hybrid pneumatic powertrain configuration for transit bus applications

In the current study, a new hybrid compressed natural gas, liquid nitrogen-based powertrain configuration is developed and analyzed for more environmentally-benign transit buses. The conceptual design extracts power from high-pressure nitrogen via three-stage expansion air motors. When the high-pressure LN2 tank level is critically low, a hydraulic pump powered via a CNG-based internal combustion engine is utilized to repressurize the liquid nitrogen. At the end of the expansion process, low-pressure nitrogen is condensed via a helium-based cryocooler system and stored in a low-pressure tank. The performance of the present conceptual system is evaluated via energy and exergy approaches. The power requirements, fuel consumption ratios and CO2 emission ratios are presented with respect to driving modes. The utilization of different fuel types as a secondary energy source for the powertrain is comparatively evaluated. The effects of various design and operational parameters on the system performance are investigated through parametric studies. The proposed system can operate with energy and exergy efficiencies of 46.6% and 67.5%, respectively while emitting 0.0768 kg CO2 eq per kilometer in city driving at a speed of 40 km/h (11.11 m/s).

Simulation on chill-down behavior and induced thermal stress of a cryogenic tank during LN2 filling

In order to illustrate the relevance between the chill-down and the thermal stress characteristics of cryogenic tanks during filling, a unidirectional thermal-structural numerical method is introduced in this paper. Aiming at the filling process of a LN2 tank, the flow field, temperature distribution and the cooling behavior of the tank wall are calculated in detail through a two-dimensional CFD model. Based on the temperature data of CFD calculations, time-ordered static structural analyses of the thermal deformation and thermal stress of the tank wall were conducted by a finite element model. Results show that, the degree of the thermal deformation is positively related to the cooling degree of the tank. The thermal stress concentrated area does not depend on the distribution of the thermal deformation, but is consistent with the position of the liquid level where exists the remarkable temperature gradient. For the bottom filling process of the target tank, the thermal stress is most serious at the beginning filling stage and the maximum appears at the tank bottom. By comparing with the experimental data, this numerical method is verified to be a useful tool for the evaluation, design, and safe operation of cryogenic tanks.

Coupling optimization of composite insulation and vapor-cooled shield for on-orbit cryogenic storage tank

The long-term storage of cryogenic propellants on orbit under thermal and pressure control is a promising enabling technology for future space exploration. Composite insulation composed of polyurethane foam (Foam), variable density multilayer insulation (VD-MLI), and a vapor-cooled shield (VCS) is considered as an effective passive thermal control method for such missions. This paper presents a theoretical model that considers three heat transfer mechanisms simultaneously within the VD-MLI and convective heat transfer inside the VCS, to predict and optimize the thermal performance of the insulation combination. The model is validated by experimental data. The influences of VCS position and warm boundary temperature (heat flux) on the thermal insulation performance are investigated for LH2, LN2, LO2, and LCH4 tanks. The temperature profiles within the insulation material with or without VCS are compared. In addition, the contributions from the VCS to reduce the heat flux into the tank are evaluated. The conclusions are valuable for the optimal design of future composite insulation with Foam/VCS/VD-MLI for cryogenic storage tanks on orbit.

A new, simple and efficient liquid nitrogen free method to cryopreserve mouse spermatozoa at −80 °C

The mouse is widely used for biomedical research and an increasing number of genetically altered models are currently generated, therefore centralized repositories are essentials to secure the important mouse strains that have been developed.We have previously reported that spermatozoa of wild type and mutant strains frozen using standard laboratory protocols can be transported in dry ice (−79 °C) for 7 days and safely stored in a −80 °C freezer for up to two years. The objective of this new study was to compare the effects of the freezing techniques using LN2 or -80 °C freezer on fertility of frozen-thawed mouse spermatozoa. After thawing, sperm fertility was comparable (P > 0,05) between the LN2 and the −80 °C samples for at least 1 year. Furthermore, we showed that it is possible to freeze and store mouse semen directly at −80 °C and eventually transfer it to LN2 irrespective of storage time. This study is relevant because it shows for the first time that mouse spermatozoa can be efficiently frozen and stored at −80 °C with no use of liquid nitrogen for a long period of time. A new, simple, efficient and flexible, liquid nitrogen free, method was developed for freezing and maintaining spermatozoa of wild type and mutant C57BL/6N lines. Lines on this genetic background are used in collaborative research infrastructures for systematic phenotyping, e.g. the International Mouse Phenotyping Consortium (IMPC) and therefore largely cryopreserved in repositories like EMMA/Infrafrontier. The importance of this finding will be especially useful for small laboratories with no or limited access to liquid nitrogen and for laboratories generating many mouse mutant lines by CRISPR/Cas9 who do not want to saturate the limited space of a LN2 tank, using a more accessible −80 °C freezer. This study underlines, once more, that mouse spermatozoa are very resistant and can be frozen, transported, shared and stored at −80 °C for a long time without a significant loss of viability. This new approach simplifies the freezing process and facilitates the long term storage of mouse spermatozoa at −80 °C, always allowing the transfer to LN2 for indefinite storage without noticeable detrimental effects.

Long term maintenance of frozen mouse spermatozoa at −80 °C

Maintaining mouse stocks as frozen materials offers both ethical and economical advantages over live animal breeding if the lines are not actively used. The European Mouse Mutant Archive (EMMA) promotes the archiving and distribution of important mouse models for biomedical research through the cryopreservation of their embryos and gametes. Embryo freezing in liquid nitrogen (LN2) at −196 °C has traditionally been the method of choice for archiving mouse lines. However, sperm freezing is emerging as a more convenient alternative due to the application of innovative cryopreservation and recovery protocols. In addition, frozen spermatozoa are less sensitive to post-freezing temperature fluctuations.We have previously reported that spermatozoa frozen using standard laboratory protocols can be safely stored in a −80 °C freezer or in dry ice (−79 °C) for at least seven days. We now report the extension of this period of maintenance at −80 °C up to two 2 years both for wild type and mutant strains, indicating that once frozen, mouse spermatozoa are quite resistant and can be transported, shared and stored at −80 °C for a long time without a significant loss of viability. The importance of this finding will be especially relevant for small laboratories with no constant access to liquid nitrogen and for labs generating many mouse mutant lines by CRISPR/Cas9 who do not want to saturate the limited space of a LN2 tank, using a more accessible −80 °C freezer.

Performance of thermodynamic vent system for cryogenic propellant storage using different control strategies

The performance of the thermodynamic vent systems (TVS) is significantly influenced by the operating parameters, initial condition, and geometry of the tank. This paper presents an experimental investigation on the effects of operating parameters on liquid nitrogen tank pressure control including different throttling modes and control strategies. Two control strategies were implemented experimentally on a TVS-equipped LN2 tank. The first strategy involves starting the pump and vent valve simultaneously once the ullage pressure increases to the upper limit of the control band. The second strategy involves operating the pump based on the ullage pressure, while the vent valve is controlled based on both the ullage pressure and bulk-liquid temperature. The results showed that the pressure-drop rate under the gas–liquid throttling mode was found to be approximately 1.95 times higher than that under the liquid-only throttling mode. The temperature increase rates of the ullage and liquid in the first strategy are slightly slower than those in the second strategy, whereas the average mass lost in the first strategy is approximately 3.25 times that in the second strategy for the same operation time. In addition, the effect of a noncondensable gas on the TVS performance was comparatively investigated.

Preliminary study on effects of bovine frozen semen storage using a liquid nitrogen-independent method on the quality of post-thaw spermatozoa

Frozen semen of eight bulls was used to assess effects of storage temperature and length of storage time on frozen-thawed bovine sperm quality. In experiment 1, 25 straws of frozen semen of each bull were allocated to 3 groups. The control was still maintained in liquid nitrogen (LN2). The rest were abruptly moved from LN2 to −80°C and −30°C mechanical freezers, respectively. After thawing, it was found that the sperm motility, vitality and membrane integrity were comparable (P>0.05) between the control and the −80°C samples and were significantly inferior (P<0.001) in the −30°C samples, irrespective of storage time (1-day, 1-week and 1-month). In experiment 2, two out of the three parts (16–18 straws) of frozen semen of each bull were rapidly removed from LN2 and further kept in the freezer (−80°C). One day before being thawed, half of the samples in the freezer were promptly put back to LN2. The results showed that the frozen-thawed sperm quality was not significantly affected (P>0.05) both by storage temperature (−196°C, −80°C and −80 & −196°C) and storage time [day-2, day-8 (1-week) and day-31 (1-month)]. At the same storage times, the quality measures at different temperatures were not significantly different from one another (P>0.05). In conclusion, a −80°C mechanical freezer was as effective as LN2 in preserving in vitro quality of frozen-thawed bovine spermatozoa throughout 1-month of storage. When required for use, frozen semen stored in the freezer could be thawed immediately or transferred to the LN2 tank for thawing elsewhere.

Study on the Operation Safety of HTS Current Leads in EAST Device

The experimental advanced superconducting tokamak (EAST) device providing excitation currents to the superconducting magnet system using 13 pairs of high temperature superconducting (HTS) current leads. It is the first fusion experimental device using HTS current leads in the world. However, there are some problems on the HTS current leads during the operation process since 2006. These problems are the key risks to the operation safety of the HTS current leads and EAST tokamak. Some solutions have been putted forward. Supercritical helium (SHe) leakage was found in the HTS current leads in 2011. It led a vacuum degeneration in the cryostat where the HTS current leads were installed. A new connecting structure between the HTS module and low temperature superconducting wires has been used to eliminate the SHe leakage problem. The flow of liquid nitrogen (LN2) cooling loops has been modified to guarantee the existence of LN2 in the cylinders at the middle of the current leads. It can avoid the quench in the HTS current leads due to the loss of coolant. And the measurement sensors have been increased to reliably monitor the temperature in the LN2 tanks to ensure the existence of LN2 in the LN2 cylinder. A water cooling structure has been added in the room temperature terminal of the toroidal field HTS current leads to avoid a temperature fast rise incident on the warm end of the resistive heat exchanger and the returning nitrogen gas under large transmission current. The operation safety of the HTS current leads in EAST device has been improved after the upgrade.

Effect of Microbial Contamination Induced during the Preservation of Ova via Vitrification (Open System)

The cryopreservation of sperm, embryos and, oocytes plays an important and increasing role in assisted reproduction, due to improvements of old, and introduction of new technologies. In parallel, concerns are increasing about the technical and biological safety of this procedures.Cryopreservation of embryos is an established tool in human assisted reproductive technologies, and the clinical application of oocyte and ovarian tissue cryopreservation is increasing worldwide. Vitrification is a cryopreservation technique that leads to a glass-like solidification, with rapid cooling of cells or tissues. Today vitrification is seen as the future of cryopreservation of human oocytes and embryos, owing to improved survival rates and clinical outcomes.The aim of this study is to investigate the hypothetical risk of disease transmission through LN2 during the vitrification procedure if the cells are directly plunged into accidentally contaminated LN2. The need to guarantee the absolute sterility of LN2 for vitrification purposes is considered a critical problem.In this study we used different kind of microbes to infect group of mice oocyte stored in the same LN2 tank. The results of this study demonstrate absence of cross infection between samples during the cryopreservation and vitrification procedures. Although the microbes have grown in different kind of media such as embryo culture media or nutrient agar media to provide ideal environment for bacterial growing and more even the vitrification seems cause degeneration microbes. However, Safe and successful cryopreservation of oocytes requires screening of patients for infectious diseases, and application of the appropriate sanitary and cryoprocedures to ensure high postthaw survival of gametes and to minimize the risk of disease transmission to recipients.

An efficient and mass reproducible method for vitrifying mouse embryos on a paper in cryotubes

To date, the most successful and popular vitrification method is based on the minimum volume cooling (MVC) concept, in which embryos are vitrified in a very small volume of vitrification solution (VS) and then stored in cryotubes in liquid nitrogen (LN2). Unfortunately, these methods need special devices and may not be suitable for vitrifying a large number of embryos. Theoretically, more embryos in VS on a paper (MVC concept) in cryotubes can be vitrified effectively. Therefore, this study directly vitrifies mouse embryos on a Kimwipes tissue in an 1.8mL cryotube. The ICR 2-celled to blastocyst embryos were used for testing this procedure. In Treatment 1, embryos transferred with 1–2μL of VS into a cryotube. Treatment 2 was similar to Treatment 1 except that the cryotube was filled with LN2. Treatment 3 was identical to Treatment 1 except that a small piece (5mm2) of a sterilized Kimwipes tissue was placed on the top of VS. Treatment 4 was identical to Treatment 3 except for the cryotube being filled with LN2. After each treatment, the cryotubes were capped and transferred to a LN2 tank. After warming, the recovered embryos were cultured in KSOM+AA for 1–3days. There were no differences in the recovery rate, overnight survival rate, blastocyst rate, and birth rate after embryo transfer among all treatment groups. Our results demonstrated an alternative simple, efficient, and mass reproducible method for vitrifying mouse embryos using papers as a vehicle and cryotubes as a container.

The relationship between pregnancy and oxidative stress markers on patients undergoing IVF/IUI

The effects of oxidative stress (OS) on female reproductive functions are not clear; however OS is believed to play an important role in endometriosis, PCOS, and unexplained infertility. The aim of this study was to investigate the impact of reproductive hormones on OS markers on women undergoing hormonal stimulation for IVF or IUI cycles. This is a prospective IRB approved study. Blood samples obtained from 15 patients undergoing ovarian stimulation with rFSH or hMG were divided into two groups. Grp-1 was baseline blood collected on day-2-3 of women cycle. Grp-2 is blood collected at the end of FSH/hMG injection. Serum was collected and stored in LN2 tanks at -196oC until analysis. Standard IVF and IUI procedures were followed. The serum levels of Superoxide Dismutases (SOD), and Interleukin-6 (IL-6) were measured by ELISA kits (Cayman Chemical); the Glutathione Peroxidase (GPx) was spectrophotometically measured (ZeptoMetrix Co.). Student's t-test was used for statistical analysis. The mean age of patients was (33.3 ± 3.4 yrs) and etiology of infertility was endometriosis (n = 7), PCOS (n = 2), and unexplained (n = 6). Results in Table-1 show a significant positive correlation between levels of E2 and that of SOD, GPx and IL-6. Pregnancies were recorded among 7 of the 15 couples. Interleukin-6 was significantly (P=0.02) higher in pregnant than non-pregnant group. SOD and GPx levels was not different between pregnant and non-pregnant groups.Tabled 1Oxidative Stress Markers & Estradiol levels in Serum of Women Before & After Hormonal Stimulations (Mean ± SEM)ParametersBeforeAfter StimulationP valueSOD (U/mL)141.0 ± 36.0178.6 ± 102.60.043GPx mU/mL464.5 ± 140604.1 ± 1100.022IL-6 (pg/ml)3.4 ± 2.315.5 ± 3.80.029E228.2 ± 10.1907.2 ± 430 Open table in a new tab The results of our study indicated that ovarian stimulation has an impact on the production of SOD, GPx and IL-6. The increased level of Interleukin-6 activity among pregnant patients is suggestive of its role in enhancing implantation.

105 CRYOPRESERVATION OF VENDA COCK SPERMATOZOA: EFFECT OF CRYOPROTECTANT FOLLOWING ANALYSIS BY COMPUTER-ASSISTED SPERM ANALYSIS

The choice of ideal permeable cryoprotectant for cock semen equilibration and freezing is critical. The aim of this study was to compare three different cryoprotectants [dimethyl sulfoxide (DMSO), ethylene glycol (EG), and propanediol (PND)] following cryopreservation. The abdominal massaging technique was used for semen collection from 5 Venda cocks. Individual ejaculates were diluted with modified Kobidil+ (mK+) extender (fraction A) at a ratio of 1:2 and equilibrated for 2 h at 5°C. Semen samples of 5 μL were taken at 0, 60, and 120 min and evaluated by CASA for spermatozoa motility parameters (rapid, medium slow, static, NPM and PM) and velocity. Semen was further diluted at 1:1 volume ratio with mK+ supplemented with 8% DMSO, EG and PND (fraction B), and equilibrated for additional 2h at 5°C and evaluated at 60 and 120 min for motility and velocity. Cooled semen were then transferred into 0.25-mL straws and placed into a programmable freezer. The temperature of the chamber was decreased in a stepwise manner, from 5°C to -20°C, at the rate of 1°C/min until it reached the target temperature. The straws were exposed to liquid nitrogen (LN2) vapor and then plunged into LN2 (-196°C). The semen straws were stored into LN2 tank at -196°C. After 3 months of storage, semen straws were thawed at 5°C and evaluated by CASA for spermatozoa motility and velocity. Data were analyzed by ANOVA. There were no significance differences between DMSO and EG regarding the survival and motility rate of frozen/thawed semen; however, these parameters were lower compared with the fresh semen. The PND was not a suitable cryoprotectant to cryopreserve Venda spermatozoa. In conclusion, ethylene glycol was found to be a suitable cryoprotectant to cryopreserve spermatozoa of South African Venda cocks. Department of Agriculture Forestry and Fisheries, NRF,ARC, Department of Science &amp; Technology.

Cord blood: from garbage to life-saving source.

Cord blood: from garbage to life-saving source.