Blue superradiance from neat semiconducting alternating copolymer films

Blue superradiant emission in thin polymer films with a low energy threshold, as reported here, offers hope for the possible development of solid-state electrically pumped polymer lasers The absorbance, emission, and fluorescence spectra of the blue-light emitting copolymer poly[dimethylsilylene-p-phenylene-vinylene-(2,5-di-n-octyl-p-phenylene)-vinytene-p-phenylene] are presented and discussed. It is suggested that lasing in the superradiant regime occurs as a result of the combination of optically induced net gain and waveguiding in the thin film

Factors promoting staying at work in people with chronic nonspecific musculoskeletal pain:a systematic review

Purpose: To identify determinants for staying at work (SAW) in workers with chronic musculoskeletal pain (CMP). Method: A systematic review of factors that promote SAW in workers with CMP. We searched the databases of PubMed, EMBASE, PsycInfo, CINAHL and the Cochrane Library. We included studies reporting on working subjects without present CMP-related sick leave. A quality assessment of GRADE criteria and evidence synthesis was performed. Results: We identified five cross-sectional studies and two qualitative studies reporting on factors associated with SAW in workers with CMP. Consistent association with SAW was found for low perceived physical disability and low emotional distress (low-level evidence). Duration of pain, catastrophizing, self-esteem and marital status were not associated with SAW (low-level evidence). Qualitative studies indicated that personal adjustments and workplace interventions are important determinants for SAW (evidence not graded). Conclusions: No high-level evidence for SAW determinants for workers with CMP was identified. Future interventions aimed at promoting SAW could consider reducing perceived physical disability and emotional distress, and promoting adjustment latitude at work, support from supervisors, and the workers' motivation and self-management skills. Further research is required because knowledge of SAW in workers with CMP is scarce, and the relevance of the subject is high

LEDs based on conjugated PPV block copolymers

A way to control the bandgap in semi-conducting polymers is by preparing polymers with a partially conjugated backbone. In our laboratory, three conjugated copolymers containing PPV trimers as light emitting chromophores have been synthesized, which emit in the blue, green and orange wavelength region. The copolymers have a well defined conjugated backbone consisting of regularly alternating terphenylene and p-phenylene-vinylene blocks. The desired control of conjugation length is achieved through steric interaction induced by the side-chains in the terphenyl blocks of the copolymer. In this paper we evaluate the electrical and optical properties of LED devices based on these conjugated PPV block copolymers

Phosphorus supplementation to natural pasture grazing for beef cows in the Western Highveld region of South Africa

Simmentaler cows grazing Cymbopogon-Themeda veld in the western Highveld region of South Africa (1985/86-1989/90) received three levels of phosphorus (P) supplementation. Dicalcium phosphate content of the supplement was manipulated to give intakes of 8 (CS), 4 (HS) or 0 (ZS) g P/cow/day during summer. All cows received supplemental P (10 g/cow/day) during winter (1986-1989). In 1990, supplemental P (10 (CW), 5 (HW) or 0 (ZW) g P/cow/day) was given in a winter maintenance supplement (protein, energy and minerals). Rainfall was above average during the trial period. Reproductive performance was not influenced by P supplementation. Mean livemass of the CS group was greatest (p 0.05) by P supplementation. Cow mass was ffected by winter P supplementation (p < 0.05). Both CW and HW displayed improved (p < 0.01) condition scores and higher (p < 0.01) bone P content than ZW. Fatalities (4) occurred in ZW due to P deficiency (74.5 mg P/cm 3 bone), and deficiency symptoms were manifested in the entire group. Both summer and winter veld is deficient in P, which makes continuous supplementation a recommended practice in this area. (South African Journal of Animal Science, 2000, 30(1): 43-52