WTC2005-63330 THE EFFECT OF DIFFERENT LUBRICATION REGIMES AND LUBRICANTS ON THE FRICTION HARD-ON-HARD TOTAL HIP REPLACEMENTS

ABSTRACT The wear of hip replacements can be dependent on serum protein levels and the swing-phase load during the gait cycle. We hypothesise that these effects may be associated with changes in the lubrication and friction of the joint. The aim of this study was to assess the effect of the lubrication regime and lubricant on the friction of metal-on-metal (MOM) and ceramic-on-ceramic (COC) THRs. Increasing the swing-phase load led to decreased fluid film thickness and an increase in friction, in both MOM and COC bearings. Increasing the protein concentration of the lubricant, decreased the friction of MOM THRs. Friction testing of COC bearings demonstrated an increase in friction as the protein concentration increased. The change in lubricating film thickness explains differences in friction and wear as the swing-phase load is changed for a given lubricant. However, when we change the lubricant composition, protein boundary lubrication effects dominate, this influences friction and wear differently in MOM and COC THRs. INTRODUCTION It has been shown previously that the wear of metal-on-metal (MOM) bearings is dependent on the swing phase load during the gait cycl

Development of monogenic lines of rice for blast resistance

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Identification of blast resistance genes in elite indica-type varieties of rice (Oryza sativa L.)

Seven blast resistance genes- Pi20, Pita, Pik (one of Pik alleles, Pik, Pik-h, Pik-m, and Pik-p), Pib, Pik-s, Piz-t, and Pia- were identified in International rice Research Institute (IRRI)- bred rice varieties through genetic analysed based on a differential system. Segregation analyses were performed using BCF populations derived from crosses of six varieties (IR34, IR36, IR60, IR74, IR46 and IR64) with a susceptible Indica-type variety C)39, and allelism tests using F populations derived from crossed of nine varieties (IR34, IR24, IR36, IR60, PSB Rcl, IR74, IR56, IR70, and IR64) with differential varieties carrying known blast resistance genes. Selected Philippine blast isolates of Pyricularia grisea (Cooke) Sacc. with known avirulence were used in the analyses. The genotype for blast resistance of each variety was identified based on a gene-for-gene relationship between resistance in rice and avirulence in the blast pathogen. Among the genes identified, Pib and Pik-s or Pik were detected in nearly all IRRI varieties used. Some genes that were not estimated from the reaction patterns of IRRI varieties in the previous analysis due to the masking effect of Pita, Pik, and Pi20 were also identified