The process of the epoxy-bonded Sm_2TM_(17) magnets includes:(1)after melting,the ingots are treated by solid soluiion,and then aged and pulverized;(2)the obtained alloy powder is mixed with epoxy resin bind- er;(3)th...The process of the epoxy-bonded Sm_2TM_(17) magnets includes:(1)after melting,the ingots are treated by solid soluiion,and then aged and pulverized;(2)the obtained alloy powder is mixed with epoxy resin bind- er;(3)the mixture is pressed in a magnetic field;(4)the compacts are cured.When the SmCo_(4.9)Fe_(2.7)Cu_(0.54)Zr_(0.13) alloy is heat treated and pressed with optimum pressing parameters,the high quality bonded magnets with B_r=8250 G,_iH_c=13000 Oe,and(BH)_(max)=16MGOe can be obtained.The stability of the magnets is studied also.The irreversible loss of O.C.(open circuit)remanence B_r in the temperature range between 25 and 150℃,is less than 4%.The average temperature coefficient at temperatures between 25 and 70℃ is-0.03%/℃.The magnets obtained have heat resistance up to 130℃ even in long-term service, and have good corrosion resistance in acid,alkali and salt solutions.展开更多
Aim: To compare the recovery rate of morphologically normal and chromatin condensed spermatozoa from native se-men samples using the SpermPrep^(TM) filtration columns and Percoll gradient centrifugation and to determi...Aim: To compare the recovery rate of morphologically normal and chromatin condensed spermatozoa from native se-men samples using the SpermPrep^(TM) filtration columns and Percoll gradient centrifugation and to determine the influenceof the two processing techniques on fertilization and pregnancy rates in an IVF-ET program. Methods: Sixteen se-men samples obtained from patient's husband were included in this study. Each was divided into two aliquots. The firstaliquot was processed with SpermPrep^(TM) filtration columns and the second, Percoll gradient centrifugation. Smears weremade before and after semen processing with both methods for the evaluation of chromatin condensation (chromomycineCMA3) as well as morphology (strict criteria) of spermatozoa. One hundred and seventy oocytes were retrieved fromthe patients and the oocytes from each patient were subdivided into two sets : one set was inseminated using spermatozoaprocessed with SpermPrep^(TM) and the other inseminated after semen processing with Percoll gradient centrifugation. Re-sults: The Percoll method yielded a significantly higher percentage of chromatin condensed (90.8 ±6.5% vs 82.3±8.8%, P = 0.017) and morphologically normal spermatozoa (12.9±7.4% vs 6.9±4.8%, P =0.001) in com-parison to SpermPrep^(TM). Whereas, sperm count recovery rate was significantly higher after the use of SpermPrep^(TM) thanafter the Percoll gradient centrifugation. The fertilization rate was similar between the two methods. Conclusion:Semen processing with Percoll should be recommended for intracytoplasmic sperm injection as the natural selection isbypassed and the SpermPrep^(TM) technique could be recommended for IVF and IUI programs as the sperm concentrationplays a more significant role in these procedures.展开更多
文摘The process of the epoxy-bonded Sm_2TM_(17) magnets includes:(1)after melting,the ingots are treated by solid soluiion,and then aged and pulverized;(2)the obtained alloy powder is mixed with epoxy resin bind- er;(3)the mixture is pressed in a magnetic field;(4)the compacts are cured.When the SmCo_(4.9)Fe_(2.7)Cu_(0.54)Zr_(0.13) alloy is heat treated and pressed with optimum pressing parameters,the high quality bonded magnets with B_r=8250 G,_iH_c=13000 Oe,and(BH)_(max)=16MGOe can be obtained.The stability of the magnets is studied also.The irreversible loss of O.C.(open circuit)remanence B_r in the temperature range between 25 and 150℃,is less than 4%.The average temperature coefficient at temperatures between 25 and 70℃ is-0.03%/℃.The magnets obtained have heat resistance up to 130℃ even in long-term service, and have good corrosion resistance in acid,alkali and salt solutions.
文摘Aim: To compare the recovery rate of morphologically normal and chromatin condensed spermatozoa from native se-men samples using the SpermPrep^(TM) filtration columns and Percoll gradient centrifugation and to determine the influenceof the two processing techniques on fertilization and pregnancy rates in an IVF-ET program. Methods: Sixteen se-men samples obtained from patient's husband were included in this study. Each was divided into two aliquots. The firstaliquot was processed with SpermPrep^(TM) filtration columns and the second, Percoll gradient centrifugation. Smears weremade before and after semen processing with both methods for the evaluation of chromatin condensation (chromomycineCMA3) as well as morphology (strict criteria) of spermatozoa. One hundred and seventy oocytes were retrieved fromthe patients and the oocytes from each patient were subdivided into two sets : one set was inseminated using spermatozoaprocessed with SpermPrep^(TM) and the other inseminated after semen processing with Percoll gradient centrifugation. Re-sults: The Percoll method yielded a significantly higher percentage of chromatin condensed (90.8 ±6.5% vs 82.3±8.8%, P = 0.017) and morphologically normal spermatozoa (12.9±7.4% vs 6.9±4.8%, P =0.001) in com-parison to SpermPrep^(TM). Whereas, sperm count recovery rate was significantly higher after the use of SpermPrep^(TM) thanafter the Percoll gradient centrifugation. The fertilization rate was similar between the two methods. Conclusion:Semen processing with Percoll should be recommended for intracytoplasmic sperm injection as the natural selection isbypassed and the SpermPrep^(TM) technique could be recommended for IVF and IUI programs as the sperm concentrationplays a more significant role in these procedures.
