363 research outputs found

    Simple Combined Model for Nonlinear Excitations in DNA

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    We propose a new simple model for DNA denaturation bases on the pendulum model of Englander\cite{A1} and the microscopic model of Peyrard {\it et al.},\cite{A3} so called "combined model". The main parameters of our model are: the coupling constant kk along each strand, the mean stretching y∗y^\ast of the hydrogen bonds, the ratio of the damping constant and driven force γ/F\gamma/F. We show that both the length LL of unpaired bases and the velocity vv of kinks depend on not only the coupling constant kk but also the temperature TT. Our results are in good agreement with previous works.Comment: 6 pages, 10 figures, submitted to Phys. Rev.

    Co-doping red-emitting Sr2Si5N8:Eu2+ into yellow-emitting phosphor-packaging for enhancing the optical properties of the 8500 K remote-phosphor packaging wleds

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    In the last decades, WLEDs attract more and more consideration in both academic and industrial purposes because of its advantages such as fast response time, environment friendliness, small size, long lifetime, and high efficiency. In this research, by doping the red-emitting Sr2Si5N8:Eu2+ phosphor particles into yellow-emitting YAG:Ce phosphor-packaging, a new recommendation for enhancing the optical properties (color uniformity, color rendering index, and lumen output) of the 8500 K remote-phosphor packaging WLEDs is presented, investigated, and demonstrated. By using Mat Lab and Light Tools software based on Mie Theory, the obtained results show that the optical properties of the 8500 K remote-phosphor packaging WLEDs significantly depended on Sr2Si5N8:Eu2+ concentration. The results have provided a potential practical recommendation for manufacturing remote-phosphor W-LEDs.Web of Science1341034102

    The clinical features of osteogenesis imperfecta in Vietnam

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    Purpose Osteogenesis imperfecta (OI) has not been studied in a Vietnamese population before. The aim of this study was to systematically collect epidemiological information, investigate clinical features and create a clinical database of OI patients in Vietnam for future research and treatment strategy development. Method Participants underwent clinical and physical examinations; also medical records were reviewed. Genealogical information was collected and family members’ phenotypical manifestations recorded. Cases were classified according to the Sillence classification. Results In total, 146 OI patients from 120 families were studied: 46 with OI Type I, 46 with Type III and 54 with Type IV. Almost patients had skeletal deformations. One hundred and forty-two had a history of fractures, 117 blue sclera, 89 dentinogenesis imperfecta and 26 hearing loss. The total number of fractures was 1,932. Thirty-four patients had intra-uterine fractures and nine had perinatal fractures. Surgery was performed 163 times in 58 patients; 100 osteosyntheses and 63 osteotomies. Bisphosphonate treatment was used in 37 patients. The number of affected individuals and predominance of severe forms of OI indicate that the disease is under diagnosed in Vietnam, especially in cases without a family history or with mild form of OI. Deformities appeared in all patients with different severity and localisation, affecting mostly the lower limbs. OI medical and surgical treatment rates are low and in most cases surgery was performed due to fractures. Conclusions Compared to previous studies, our results indicate a lower OI prevalence and greater severity of symptoms in the Vietnamese population when compared with other areas. Further investigation, improved diagnosis and treatment are needed to increase the patients’ quality of life
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