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1.
Equine embryos recovered on Day 6 after ovulation were cooled to +4 degrees C, or frozen with AFP alone or together with glycerol. Twenty embryos (140-200 microm in diameter) were randomly assigned to 6 treatment groups. In the first 3 groups, the embryos were cooled from room temperature to +4 degrees C at a rate of 3 degrees C/min and warmed again at a rate of 32 degrees C/min in a programmable freezer. In the second 3 groups, the embryos were frozen using a standard protocol, stored in liquid nitrogen for 5-7 days and then thawed in a 37 degrees C waterbath. After cooling/warming or freezing/thawing all the embryos were stained with DAPI. The percentage of dead cell area was significantly lower in the cooling groups than in the freezing groups and no significant differences were apparent between the cryoprotectants used in the study.  相似文献   

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The pearlitic hardenability of a high-purity Fe-0.8 pct C alloy and zone-refined iron binary alloys containing Mn, Ni, Si, Mo, or Co was studied by means of hot-stage microscopy. The binary alloys were carburized in a gradient furnace to produce eutectoid compositions, thus eliminating proeutectoid phases. A special technique based on hot-stage microscopy was used to study the effect of cooling rate (10°F/min to 25,000°F/min) on the transformation of austenite and provided data for the construction of continuous cooling-transformation diagrams. From these diagrams critical cooling rates were obtained for hardenability calculations. It was found that molybdenum is the most effective element, followed by Si, Ni, Co, and Mn, in suppressing the pearlite transformation,i.e., in increasing the hardenability of the alloys studied. The alloying additions were grouped into two classes according to their effect on hardenability: α-stabilizers (Mo and Si) and γ-stabilizers (Ni, Co, Mn), with the α-stabilizers being the more effective in improving hardenability. This paper is based on a presentation made at a symposium on “Hardenability” held at the Cleveland Meeting of The Metallurgical Society of AIME, October 17, 1972, under the sponsorship of the IMD Heat Treatment Committee.  相似文献   

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The effect of cyclosporine (CsA) on fertility has assumed greater importance with the increasing numbers of pediatric transplantations being performed all over the world. Conflicting reports on the effects of CsA on sex hormones are available. This experimental animal study was designed to examine the effect of CsA on testicular weight, sperm counts, seminiferous tubular diameter (STD), testicular morphology, DNA flowcytometry, sex hormone levels, and fertility in male rats. Those rats who received CsA (20 mg/kg per day) showed significant reductions in testicular weight (P < 0.05), sperm count (P < 0.01), Johnsen score (P < 0.05), STD (P < 0.01), serum testosterone levels (P < 0.05), haploid cell population (P < 0. 001) in the testis, and fertility (P < 0.001) compared to those receiving CsA 10 mg/kg per day and control rats. These findings will have an important bearing for children receiving cyclosporine for long periods to guide the physician in optimally adjusting long-term treatment.  相似文献   

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指出当前该厂轧钢生产中,轧辊作为大型工具在降低成本中的重要性。简要分析高温应力掰棍的力学原理,指出高温对轧辊寿命的影响,提出采取优化冷却水控制提高轧辊寿命的措施。并描述轧辊与坯料氧化铁皮之间磨损带来的轧辊缺陷,以及该厂BD2轧辊毛刺与氧化铁皮的关系。对冷却控制和减少氧化铁皮给出一些预防措施。  相似文献   

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吕勇  裴翠红 《包钢科技》2002,28(3):80-83
通过对包钢炼铁厂二烧车间工艺改造后的生产实践和测试数据作分析讨论,说明机上冷却工艺有利于除尘系统的正常工作,有利于简化除尘设备改善环境;是烧结行业保护环境的发展方向.  相似文献   

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In adult and neonatal goats, we chronically implanted thermodes on the ventrolateral (VLM) medullary surface to create reversible neuronal dysfunction and thereby gain insight into the role of superficial VLM neurons in control of breathing in anesthetized, awake and asleep states. Consistent with data of others, cooling caudal area M and rostral area S caused sustained apnea under anesthesia. However, in the awake and NREM sleep states, cooling at this site caused only a modest reduction in breathing, indicating that neurons at this site are not critical for respiratory rhythm in these states. Moreover, data in the awake state over multiple conditions suggest neurons at this site do not integrate all intracranial and carotid chemoreception. The data suggest though that neurons at this site have a facilitatory-like effect on breathing both unrelated and related to intracranial chemoreception. We believe that this facilitation serves a function similar to the facilitation provided by the carotid chemoreceptors and by sources associated with wakefulness. Accordingly, elimination/attenuation of any one of these three influences (caudal M rostral S VLM, wakefulness, carotid chemoreception) results in a slight decrease in breathing, removal of two of the three results in a greater decrease in breathing, and removal of all three results in sustained apnea.  相似文献   

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Red blood cells from HBSAg-positive blood were washed in the Fenwal Elutramatic, Haemonetics Processor 15, or the IBM Blood Processor with sodium chloride solutions, or in the Huggins Cytoglomerator with sugar solutions. The Fenwal Elutramatic and IBM Blood Processor were the most efficient washing systems, the Haemonetics Processor 15 was less efficient, and the Huggins Cytoglomerator was the least efficient in removing the HBSAg. Washing to remove the HBSAg from red blood cells containing 40 per cent W/V glycerol in an ionic medium was more efficient than washing HBSAg from liquid-stored red blood cells or red blood cells containing 20 per cent W/V glycerol. The original and modified dilution/agglomeration wash cycles used in the Huggins Cytoglomerator were not able to remove the HBSAg from units of blood that were radioimmune assay (RIA) positive and counterelectrophoresis (CEP) negative. Freezing had no effect on the removal of the HBSAg in vitro, whereas the concentration of 40 per cent W/V glycerol in the red blood cells that were washed did. HBSAg was not found in the amorphous debris remaining in the polycarbonate disposable bowl used in the Haemonetics Processor 15 or in the microaggregates remaining in washed red blood cells.  相似文献   

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Based on the galvannealed phase transformation theory,the phase and powder level of a galvannealed coating produced on one of the galvanizing lines at Baosteel*s cold-rolling plant were analyzed under different conditions before and after a technical innovation was introduced.After the introduction of the technical innovation,heating and cooling abilities of the galvannealing furnace were strengthened,galvanizing speed increased from 75 to 100 m/min,and the galvannealing target temperature could be reached more quickly.As such,the 8,phase was more uniform and dense,and the coating's anti-powdering ability was increased.Although the galvanizing time was slightly shortened,this had no negative effect on the anti-powdering ability of the galvannealed coating.  相似文献   

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Metallurgical and Materials Transactions A - The effect of variations in cooling rate on the morphology and kinetics of pearlite was studied and was contrasted with the isothermal and isovelocity...  相似文献   

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Conducted 3 polydipsia experiments with a total of 26 female Sprague-Dawley rats, 6 of which were implanted with thermodes and thermistors and 2 of which were implanted with thermistors alone in the medial preoptic area or posterior hypothalamus. A cold (5.C) ambient temperature reduced the amount of water consumed by food-deprived Ss tested with a VI schedule of reinforcement, while a warm (30.C) ambient increased water intake. Response rate in the cold was twice that in a neutral temperature. A hot (38.C) ambient suppressed the rate of responding and drinking. Cooling the hypothalamus substantially reduced water intake in a neutral ambient temperature. Ambient temperature affected the volume of a drink but not the frequency of drinking, while hypothalamic cooling affected both volume and frequency. Water temperature had little effect on polydipsia although less cold water was consumed than warm water. It is concluded that schedule-induced polydipsia is a temperature-dependent phenomenon. (39 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

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OBJECTIVE: To evaluate seminal oxidative stress in men after vasectomy reversal and to determine whether seminal oxidative stress could predict fertility after vasectomy reversal. DESIGN: Measurement of seminal reactive oxygen species (ROS) and total antioxidant capacity (TAC) in normal donors, men who were fertile after vasectomy reversal, and men who were infertile after vasectomy reversal. SETTING: A male infertility clinic of a tertiary care center. PATIENT(S): Thirty men who underwent vasectomy reversal and 17 normal donors. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Semen characteristics, seminal ROS, and TAC were measured with chemiluminescence assays in samples from donors and reversal patients. RESULT(S): Mean adjusted seminal ROS (log [ROS+1]) was higher in infertile reversal patients (2.38+/-0.25) than in normal donors (1.30+/-0.14). Seminal ROS was also higher in all (fertile and infertile reversal combined) reversal patients than in donors. Total antioxidant capacity did not differ between groups. The ROS-TAC score, a composite index of seminal oxidative stress, was a significant predictor of fertility. A ROS-TAC score of 45 or greater had a positive predictive value of 73% in predicting fertility. CONCLUSION(S): Seminal oxidative stress is associated with vasectomy reversal. The ROS-TAC score is a possible predictor of infertility after vasectomy reversal.  相似文献   

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OBJECTIVE: To evaluate the influence of cryopreservation temperature on human sperm motility and morphology. DESIGN: Controlled study, investigator was blinded to the type of cryopreservation. SETTING: University-based andrology laboratory. PATIENT(S): Sixteen semen samples with normal motility and sperm count from men after a fertility work up. INTERVENTION(S): Semen aliquots were either stored in a mechanical freezer at -70 degrees C or in liquid nitrogen at -196 degrees C for 7 days or 3 months. Test yolk buffer was used as a cryoprotectant. With use of a programmable freezing unit, all samples were cooled at a controlled rate. MAIN OUTCOME MEASURE(S): Sperm motility and morphology. RESULT(S): After 7 days of cryopreservation, there was a greater decrease in sperm motility among specimens maintained at -70 degrees C than among those maintained at -196 degrees C (47% versus 39% decrease). The difference in sperm motility was even greater after 3 months of cryopreservation (72% versus 39% decrease). No difference in postthaw sperm morphology was detected among sperm preserved at -70 degrees C versus -196 degrees C. CONCLUSION(S): Sperm cryopreservation at -196 degrees C is superior to cryopreservation at -70 degrees C. Sperm can be stored at -70 degrees C for a short period of time with a relatively modest loss of motility.  相似文献   

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《Acta Metallurgica Materialia》1993,41(10):2933-2937
A critical area in nanocrystalline materials research is development of grain growth relations for controlled, uniform heating or cooling. Theoretical relations describing nonisothermal coarsening are derived in terms of classical isothermal materials properties. An effective temperature is defined as the temperature at which equivalent coarsening occurs to that predicted during the heating or cooling period. This parameter is only a function of the endpoint temperatures and the activation energy for grain growth. Simplifications of the equations for grain size and effective temperature are derived and their implications discussed.  相似文献   

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