The effect of atmospheric plasma treatment of recycled carbon fiber at different plasma powers on recycled carbon fiber and its polypropylene composites

To increase the mechanical properties of recycled carbon fiber-reinforced polypropylene (PP) composites, recycled carbon fibers (RCF) were subjected to atmospheric plasma treatment at different plasma powers (100, 200, and 300 W). The changes on surface topography and roughness of RCF were examined by atomic force microscopy. Plasma treatment of RCF increased the roughness value of RCF. The variation of surface elemental compositions and tensile strength of RCF were determined by using X-ray photoelectron spectroscopy and tensile test, respectively. Plasma-treated RCF-reinforced PP composites were fabricated using high speed thermo-kinetic mixer. Plasma treatment of RCF at 100 W increased the tensile and flexural strength values of RCF-reinforced PP composites considerably by 17 and 11%, respectively. However, plasma treatment of RCF at higher plasma powers (200 W and 300 W) decreased tensile and flexural strength values of composites because of the etching of RCF. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47131.     

Sperm storage in females of the smooth newt (Triturus v. vulgaris L.): I. Ultrastructure of the spermathecae during the breeding season

Sperm storage in cloacal spermathecae was studied in females of Triturus v. vulgaris collected early in the breeding season in southern England. Females collected in terrestrial situations, presumably unmated, were mated in the laboratory, and the ultrastructure of the transferred sperm and the spermathecae was observed at various intervals after mating. Sperm from a spermatophore cap lodged in a female's cloacal orifice can migrate into spermathecae within 1 hr after mating. Spherical structures on the axial fibers of some sperm in the cap could indicate immaturity. Disorderly clusters of sperm from the cap are still present in the cloacal chamber 12 hr after mating but are absent 24 hr after mating. During storage, sperm often are in tangled masses in the spermathecal tubules. The sperm are coated with spermathecal secretions, and some sperm nuclei were observed embedded in the spermathecal epithelium. Little evidence for spermiophagy early in the breeding season was found. During oviposition, mazes of sperm occur external to the spermathecal orifices, and sperm may be released in this condition onto eggs as they pass through the cloaca. The tangled clusters in which sperm are found from pick-up to oviposition are hypothesized as an adaptation to reduce the effectiveness of sperm competition from the ejaculates of rival males. Additional studies, using the same protocol and covering the entire cycle of sperm storage, are necessary to enable interspecific comparisons leading to phylogenetic hypotheses.     

The forestry work environment and its ergonomic requirements

The paper describes chief instruments of forest production and their ergonomic requirements. The level of mechanization in the forestry production differs from high in logging and roadbuilding to a considerably lower one in silviculture, where nursery production stands out with the level of mechanization equalling that of agriculture. Ergonomic requirements greatly depend on the attitude of a particular social environment towards work safety. Some ergonomic requirements take the form of standards, recommendations or agreements. The chain saw is characterized not only by ergonomic-technical properties but also by mass, noise and vibration. Over the past three and a half decades, each of these parameters has come to conform to stricter and stricter requirements. Mass has been reduced to less than 8 kg, noise near the cutter's ear to about 100 dB(A), and the estimated acceleration transfer to the hand/arm system (WAS) below 12.5 m/s2 (frequently even below 10 m/s2).     

Kikuchi''s histiocytic necrotizing lymphadenitis associated with ruptured silicone breast implant

Mortality rates and injuries requiring medical treatment associated with sports and exercise are generally low. However, higher injury rates are reported for athletes and members of sports clubs. This study focuses on the sport- and exercise-related injury rate for various age and sex groups in the general population and how sport and exercise injury rates compare with those for other activities. The data presented are based on telephone interviews. Of the participants (N = 6,596), 335 (5.1%) reported having sustained an injury in the previous month; 46% of injuries among males and 14% of those among females were sport or exercise related. The data show a downward trend in sport- and exercise-related injury rates with increasing age. It is concluded that, as a proportion of all injuries sustained, the sport- and exercise-related injury rate is high, particularly among males. Possible future research on sport- and exercise-related injuries is discussed.