With the onging trend of weight saving in automobiles, the application of light alloys is increasing. Recently, aluminum powder metallurgy has been the subject of renewed attention due to the combination of lightweight of aluminium and the efficient material utilisation of the powder metallurgical process, which offer attractive benefits to potential end-users. This study is to explore the use of warm compaction process to aluminium powder metallurgy. This paper presents a detailed study of the effect of warm compression and sintering conditions on the resultant microstructures and mechanical properties of Al-Cu-Mg-Si PM blend.

This study was carried out to evaluate the effects of washing medium, breed and washing temperature of fresh and frozen-thawed boar sperm on mitochondrial activity and membrane integrity by flow cytometry. More than 80% of fresh sperm washed with mTLP-PVA medium at 20℃ exhibited an intact membrane and a functional mitochondrion. With frozen-thawed samples, a large number of sperm showed both damaged membrane (36.4~46.9%) and nonfunctional mitochondrion (55.1~71.1%) in the mTLP-PVA and BTS washing media at 20℃. There were no breed effects of fresh and frozen-thawed sperm on mitochondrial activity and membrane integrity. The percentages of damaged membrane of fresh and frozen sperm, respectively, were higher at 4℃ washing temperature than at 20℃ washing temperature in the mTLP-PVA medium. We found that washing medium and washing temperature of fresh and frozen-thawed boar sperm were important for the analyses of mitochondrial activity and membrane integrity by flow cytometry.

In the present study, we investigated the effects of genotypes on in vitro maturation and fertilization in porcine fresh/frozen-thawed oocytes. The porcine cumulus-oocyte complexes (COCs) were divided into four groups according to whether they were: (1) in vitro matured; (2) cryopreserved and in vitro matured; (3) in vitro fertilized and (4) cryopreserved, and in vitro fertilized. Maturation of porcine COCs was accomplished by incubation in NCSU23 medium. Immature oocytes were cryopreserved by Open Pulled Straws (OPS) method according to Vajta et al., (1998). Oocytes stained by Acetic-Orcein method were observed under the microscope. DNA extracted from the ovaries was analyzed by RAPD (random amplified polymorphic DNA) and SSCP (single strand conformational polymorphisrrt) method. The rates of oocytes maturation and fertilization were significantly high in AA genotype. The results indicated that in vitro maturation and fertilization in porcine fresh/frozen-thawed oocytes may be affected by genotypes in pigs.

Mucin coat is deposited on the embryos during passage through the oviduct in rabbit. When in vitro cultured blastocysts were transferred to the recipients, the lack of mucin coat might account in part for failure of pregnancy after transfer. The present study were carried out to investigate whether deposition of mucin coat were induced when in vitro cultured blastocysts were transferred to recipients. At 19 ～20 hours post-coitus one-cell embryos were collected by flushing oviducts. These embryos cultured for 72 hours were reached to blastocyst stage. And these blastocysts were transferred to the oviduct of asynchronized (one day later than the donors) and synchronized recipient. To confirm deposition of the mucin coat, blastocysts transferred to the oviduct were recovered at 24 and 48 hours after the transfer. Fifty eight percent of blastocysts recovered from uterus of asynchronous recipient at 24 hours after transfer and 92.9% of blastocysts recovered from uterus of synchronous recipient were 0～10 ㎛ of mucin coat thickness. And 11.8% of blastocysts of asynchronized recipients and 7.1% of blastocysts from asynchronized recipients were in 11～20 ㎛ of mucin coat thickness. When blastocysts were recovered from uterus at 48 hours after transfer, 87.0% of blastocysts from asynchronized recipients and 5.9% of blastocyst from synchronized recipients were in 0～10 ㎛ of mucin coat thickness. And 76.5% of blastocysts of synchronized recipients and 4.4% of blastocysts from asynchronized recipients were in 11～20 ㎛ of mucin coat thickness. From these results it is speculated that the low implantation rate of in vitro cultured rabbit blastocysts transferred to oviduct of recipient was caused by high degeneration of the embryo after transfer and inappropriate deposition of mucin coat.

Transgenic mice containing GH Receptor (GHR) gene fused to metallothionein promoter were analyzed to evaluate effect of GHR expression on growth in vivo. Three founder mice lines contained copies of GHR transgene and transmitted these genes into F₁ and F₂ progenies. The mRNA expression of transgene was identified using RT-PCR with GHR genes in tissues. To analyze the effects of transgenes on growth performance, body weights of pups were measured at 4, 10 and 14 weeks after birth. The body weight of transgenic mice was higher compared with that of non-transgenic control mice regardless of sex (P<0.05). Body weights between transgenic and non-transgenic mice were increased with aging. Overall, GHR transgenic mice tended to grow about 10 to 15 ％ faster than non-transgenic mice without any pathological defects.

This study was carried out to investigate the effect of cysteamine addition during in vitro maturation, fertilization and culture of porcine oocytes. Oocytes were matured for the first 22 h in mTCM -199 media supplemented with or without 150 μM cysteamine. They then were matured for an additional 22 h in mTCM-199 media without hormones supplemented with or without 150 μM cysteamine. When cumulus-oocyte complexes (COCs) were matured in the mTCM-199 media supplemented with cysteamine, the rates of GVBD and maturation (metaphase Ⅱ) were enhanced as compared to the media without the addition of cysteamine. Also, when COCs were matured in the mTCM-199 media supplemented with cysteamine, the rates of sperm penetration, male pronucleus formation, cleavage and blastocyst formation after in vitro fertilization were enhanced as compared to the media without the addition of cysteamine. In conclusion, it was suggested that oocytes matured for the first 22 h in mTCM-199 media supplemented with 150 μM cysteamine increased the rates of metaphase Ⅱ, sperm penetration, male pronucleus and blastocyst formation were higher as compared to the media without addition of cysteamine.