Selective laser fiber welding on woven polymer fabrics for biomedical applications.

Localized cartilage damage is a common problem for younger patients. This can heal, but often results in a painful condition that requires intervention. A welded-woven three-dimensional polymer fabric has been suggested as a suitable cartilage replacement because such materials closely match the mechanical properties of cartilage. However, such materials fare poorly when evaluated with respect to wear. A microscopic investigation of wear mechanisms showed that it is critical that the fibers not deflect laterally under a normal load. This observation led to the use of a new process for selective laser welding of the surface layers of three-dimensional fabrics in order to improve their wear resistance. Experimental evaluations were made in a pin-on-disc arrangement with a biomimetic loading. All materials used in the studies have previously been used in orthopedic devices or meet the requirements for United States Pharmacopeial Convention (USP) Class VI biocompatibility approval. The wear rates were significantly reduced and the lifespan of the fabrics was markedly improved due to surface welding, making this a viable option for cartilage replacement in vivo.

Influence of polar groups in binary polymer blends on positronium formation.

The present work studied the role of the polar group unconjugated oxygen on the inhibition of positronium (Ps) formation in two binary blends made from a set of chosen constituent polymers with polar and weakly polar groups (nonpolar). The polymer blend samples of PVC-EVA and PVC-SAN were investigated by coincidence Doppler broadening and positron lifetime techniques. The strong polar acetate group in the EVA contributed to positron annihilation with electrons of unconjugated oxygen (-C(+)=O(-)) as revealed by the momentum distribution curves peaking around 17 P(L) (10(-3) m(0)c). The ortho-Ps intensity indicated the unconjugated oxygen shows about a 28% Ps reduction even in the presence of a strong Ps inhibiting halogen (Cl(-)). In contrast, this effect was not seen in the PVC-SAN blends since SAN contains a weakly polar (nonpolar) acrylonitrile group (C≡N). Our results indicate the chlorine of PVC in the blends is a major contributor to Ps inhibition through the formation of a (Cl(-)-e(+)) bound state but the unconjugated oxygen in EVA of the PVC-EVA blend also plays a similar, but lesser, role.

Two new species of Rhabdias (Nematoda: Rhabditida: Rhabdiasidae) in anuran hosts from Dehradun (Uttarakhand), India.

Rhabdias himalayanus n. sp. from the lungs of Duttaphrynus himalayanus and Rhabdias dehradunensis n. sp. from the lungs of Nanorana minica from Dehradun, India are described and figured. Of the 3 previously described Indian species, Rhabdias himalayanus n. sp. is most similar to Rhabdias shortii in having a cylindrical corpus, inflated cuticle, and conical tail; it differs from R. shortii in having greater body measurements, longer esophagus, larger eggs, and a different pattern of cuticle inflation at the vulva and tail region. Rhabdias dehradunensis n. sp. is most similar to Rhabdias bulbicauda in that both possess a swollen posterior end; it differs from R. bulbicauda by having a subterminal anus, a prominent tail, and a postequatorial vulva.

Three new species of Digenea (Batrachotrematidae) in Nanorana minica (Anura, Dicroglossidae) from Uttarakhand, India.

Three new species of batrachotrematid trematodes from the small paa frog, Nanorana minica, collected in Uttarakhand, India are described and illustrated: Batrachotrema korbaensis sp. nov., Opisthioparorchis dehradunensis sp. nov. and Opisthioparorchis nanoranae sp. nov. The new species are assigned to genera based on presence or absence of cuticular spines; absent in Batrachotrema, present in Opisthioparorchis. Five species are assigned to Batrachotrema, which are separated by position of genital pore, location of testes and host; B. korbaensis differs from previously described species in that it is the only species from an anuran host with testes in the 4th quarter of the body. Ten species are assigned to Opisthioparorchis, which are separated by testes position, extent of vitellaria, and oral sucker-acetabulum ratio. O. nanoranae sp. nov. is the only species possessing tandem testes. Two species, O. dehradunensis sp. nov. and O. yaanensis, possess oblique testes, the remaining 7 species have symmetrical testes. Opisthioparorchis dehradunensis sp. nov. is distinguished from O. nanoranae sp. nov. by testes orientation; oblique in O. dehradunensis sp. nov., tandem in O. nanoranae sp. nov.

Helminth parasite communities in anuran amphibians of Kalesar Wildlife Sanctuary (Haryana), India.

Helminth parasite fauna in anuran amphibia were investigated during the general faunistic surveys of Kalesar Wildlife Sanctuary, situated in Haryana state. Three species of amphibian hosts were found to harbour 12 genera of helminth parasites. The prevalence, intensity and abundance were studied. Euphlyctis cyanophlyctis harboured maximum parasite species followed by Fejervarya limnocharis and Duttaphrynus melanostictus. In E. cyanophlyctis, among nematode parasites, the genus Camallanus was most prevalent followed by Cosmocerca and Cosmocercoides, whereas, Rhabdias and Aplectana were the least prevalent genera. Among trematode parasites, Ganeo was the most prevalent genus and least was Diplodiscus. Acanthocephalus was recovered only once and no cestode infection was found. In F. limnocharis, the most prevalent nematode genus was Oxysomatium, followed by Cosmocerca and the only trematode recorded was Ganeo, whereas, cestode Proteocephalus was also recovered once. In D. melanostictus, only two nematode genera were recovered of which Oxysomatium was dominant followed by Cosmocerca. The helminth parasite community in anuran amphibia of Kalesar WLS comprised 52.9% of nematodes, 46.2% of trematodes, 0.58% cestodes and 0.29% acanthocephala.