Investigation on Infectious Agents of Aborted Pig Fetuses and Its Correlation with PRRSV MLV Vaccine

Infectious agents causing aborted fetus problems in domestic pigs were investigated in this study. More than 10 different infectious agents were known to cause abortion in swine and the major eight viruses among them were inspected. One hundred twelve samples of aborted fetuses from nine provinces in South Korea were collected during April to November, 2013 in this study for the diagnosis of infectious agents causing abortions in pigs. Eight major infection viruses were examined in this study mainly using various diagnostic kits and reverse transcriptase polymerase chain reaction （RT-PCR）. Positive rate of the detection differed from each viruses. In this study, the main focus was the porcine reproductive and respiratory syndrome virus （PRRSV）, which took the second large portion in the positive rate of detection, and then its ORF5 gene was compared with modified live virus （MLV） vaccine strain to figure out the influence of vaccine on disease. Between four positive samples＇ sequence, two of them were 99.9%-100% similar to MLV vaccine strain and two other samples were 88.6%-92.7% similar. Similarity rate of the sequences between the vaccine and virus from aborted fetuses are very crucial, because it implies that abortion in swine can be made due to the usage of vaccine not only by the infection of field virus, and if MLV vaccine actually do have an impact on the infection, usage of the vaccine should be reconsidered.

A new strengthening mechanism driven by disruptive shear and solute segregation during warm rolling in 1.4 GPa class 12.5 wt% Al added-FeMnC ultra-lightweight steel

Novel strengthening of Fe-29.1Mn-12.5Al-1.35C-4.95Cr steel achieved by warm rolling was investi-gated.The solution-treated steel consisted of aγ-matrix containing nano-sizedκ-carbide((Fe,Mn)_(3) AlC)and elongated prior ferrite,which was transformed into FeAl-type B2 and Fe_(3) Al-type D0_(3) phases.The solution-treated steel exhibited poor strain hardening owing to glide softening associated withκ-carbide shearing by dislocations.However,after warm rolling with a reduction ratio of 30%at 300℃,the yield and tensile strengths significantly increased from 917 to 1300 MPa and 1025 to 1419 MPa,respectively.The tensile test conducted at 300℃to simulate warm rolling exhibited serrated flows,indicating dy-namic strain aging(DSA).Atom probe tomography exhibited that the C atoms inκ-carbide were swept away along the slip direction by disruptive shear during rolling at 300℃.The swept C atoms along the slip direction interacted strongly with dislocations at 300℃,with repeated pinning and breakaway of dislocations from the C atoms.This contributed to significant strengthening owing to the formation of a solute-rich atmosphere after warm rolling.The results of the tensile tests at 300℃indicated that the de-gree of strengthening was proportional to the pre-strain level.Tensile strength of 1.4 GPa can be achieved with good ductility(17%elongation)by warm rolling.This novel warm-rolling strengthening method ex-pedites the potential application of Fe-29.1Mn-12.5Al-1.35C-4.95Cr as a 1.4 GPa class ultra-lightweight steel.