the effect of an electroless ni-cu-p coating on the fatigue behavior of quenched and tempered ck45 steel has been investigated. the fatigue tests under rotating bending conditions have been conducted in three different conditions of uncoated, as-deposited and shot peened prior to the coating deposition. the results indicate that plating of the base steel leads to a fatigue life reduction. the d...

The spermatozoon is the most diverse cell type known and this diversity is considered to reflect differences in sperm function. How the diversity in sperm morphology arose during speciation and what role the different specializations play in sperm function, however, remain incompletely characterized. This work reviews the hypotheses proposed to explain sperm morphological evolution, with a focu...

Freeze-storage of epididymal sperm is an important technique for the preservation of gametes in animals, including those becoming extinct. We froze canine sperm recovered from the cauda epididymis and investigated the fertility. The qualities of sperm from the cauda epididymis before freezing were: mean sperm motility, 89.4 +/- 1.6 (SE) %; sperm viability, 89.1 +/- 1.1%; and these were signific...

Tightly bonding of bioactive coating is the first crucial need for orthopaedic implants. This study describes a novel and convenient technique to prepare bioactive coating with high adhesion on orthopaedic substitutes made of polymeric matrix. Here, a chemical corrosion method has been adopted to fabricate a coating on the surface of injection-moulded polyamide66 (PA66) substrates by corrosive ...

In polyandrous species, sperm morphometry and sperm velocity are under strong sexual selection. Although several hypotheses have been proposed to explain the role of sperm competition in sperm trait variation, this aspect is still poorly understood. It has been suggested that an increase in sperm competition pressure could reduce sperm size variation or produce a diversity of sperm to maximize ...

the objective of this study was to evaluate the importance of environmental and genetic factors affecting semen quality; sperm volume (sv), sperm concentration (spco), total sperm (ts), fresh sperm motility (fsm), total fresh motile sperm (tfms), post thaw sperm motility (ptsm), total post thaw motile sperm (tptms), number of produced payout (npp), number of fresh motile sperm in each milt ejac...

Past studies have suggested that mouse sperm surface galactosyltransferase may participate during fertilization by binding N-acetylglucosamine (GlcNAc) residues in the zona pellucida. In this paper, we examined further the role of sperm surface galactosyltransferase in mouse fertilization. Two reagents that specifically perturb sperm surface galactosyltransferase activity both inhibit sperm-zon...

Spermatozoa are amongst the most variable cells, and three factors are thought to account for this variation in design: fertilization mode, phylogeny, and postcopulatory sexual selection. In addition, it has long been assumed that a tradeoff exists between sperm size and number, and although postcopulatory sexual selection affects both traits, empirical evidence for a tradeoff has so far been e...

BACKGROUND The aim of this study was to determine if only sperm with double stranded DNA could bind to the human zona pellucida (ZP). METHODS Sperm samples from 124 infertile men with a range of semen abnormalities were studied. Oocytes that had failed to fertilize in IVF or ICSI were used for the sperm-ZP binding test. A group of four oocytes were incubated for 2 h with 2 x 10(6)/ml motile s...

Sperm competition is generally thought to drive the evolution of sperm miniaturization. Males gain advantage by transferring more sperm, which they produce by dividing limited resources into ever smaller cells. Here, we describe the opposite effect of size on the competitiveness of amoeboid sperm in the hermaphroditic nematode Caenorhabditis elegans. Larger sperm crawled faster and displaced sm...