Thin films comprising nitrogen-doped ultrananocrystalline diamond/hydrogenated amorphous-carbon(UNCD/a-C:H)composite films were experimentally investigated.The prepared films were grown on Si substrates by the coaxial...Thin films comprising nitrogen-doped ultrananocrystalline diamond/hydrogenated amorphous-carbon(UNCD/a-C:H)composite films were experimentally investigated.The prepared films were grown on Si substrates by the coaxial arc plasma deposition method.They were characterized by temperature-dependent capacitance-frequency measurements in the temperature and frequency ranges of 300-400 K and 50 kHz-2 MHz,respectively.The energy distribution of trap density of states in the films was extracted using a simple technique utilizing the measured capacitance-frequency characteristics.In the measured temperature range,the energy-distributed traps exhibited Gaussian-distributed states with peak values lie in the range:2.84×10^(16)-2.73×10^(17)eV^(-1)cm^(-3)and centered at energies of 120-233 meV below the conduction band.These states are generated due to a large amount of sp^(2)-C andπ-bond states,localized in GBs of the UNCD/a-C:H film.The attained defect parameters are accommodating to understand basic electrical properties of UNCD/a-C:H composite and can be adopted to suppress defects in the UNCD-based materials.展开更多
Background:Intestinal schistosomiasis due to Schistosoma mansoni was first reported in Oman in 1979.We describe the trend in parasitological and serological prevalence of human infection with S.mansoni in the endemic ...Background:Intestinal schistosomiasis due to Schistosoma mansoni was first reported in Oman in 1979.We describe the trend in parasitological and serological prevalence of human infection with S.mansoni in the endemic area over the period 1982–2014,and the compliance of data generated by the national monitoring and evaluation system with schistosomiasis elimination criteria set by the Ministry of Health of Oman.Methods:Parasitological and serological assessments were carried out on population(mainly children)living in the area at risk for schistosomiasis in Dhofar,the country’s only endemic Governorate,for a period of over 30 years.Kato-Katz thick smear and Indirect Haemagglutination Assay were the techniques employed.Results:Data indicate a progressive decline in prevalence of S.mansoni throughout the 1980s and the 1990s,a recrudescence in the early 2000s,and a more marked decrease following the implementation of six rounds of mass treatment with praziquantel from 2007 to 2013.Latest parasitological prevalence(2011)was 0%,while latest serological prevalence(2014)was 0.11%.Conclusion:Transmission of schistosomiasis has reached very low levels in Oman.Elimination criteria established by the Ministry of Health of Oman(parasitological prevalence≤1%and serological prevalence≤5%)have been met since 2008.Further investigations are required to assess whether interruption of transmission has been achieved in some or all foci,in view of the establishment of a formal verification process under the auspices of WHO.展开更多
文摘Thin films comprising nitrogen-doped ultrananocrystalline diamond/hydrogenated amorphous-carbon(UNCD/a-C:H)composite films were experimentally investigated.The prepared films were grown on Si substrates by the coaxial arc plasma deposition method.They were characterized by temperature-dependent capacitance-frequency measurements in the temperature and frequency ranges of 300-400 K and 50 kHz-2 MHz,respectively.The energy distribution of trap density of states in the films was extracted using a simple technique utilizing the measured capacitance-frequency characteristics.In the measured temperature range,the energy-distributed traps exhibited Gaussian-distributed states with peak values lie in the range:2.84×10^(16)-2.73×10^(17)eV^(-1)cm^(-3)and centered at energies of 120-233 meV below the conduction band.These states are generated due to a large amount of sp^(2)-C andπ-bond states,localized in GBs of the UNCD/a-C:H film.The attained defect parameters are accommodating to understand basic electrical properties of UNCD/a-C:H composite and can be adopted to suppress defects in the UNCD-based materials.
基金Field activities reported in this article were implemented by the Ministry of Health of Oman over a period of 33 years,through national budget allocations.
文摘Background:Intestinal schistosomiasis due to Schistosoma mansoni was first reported in Oman in 1979.We describe the trend in parasitological and serological prevalence of human infection with S.mansoni in the endemic area over the period 1982–2014,and the compliance of data generated by the national monitoring and evaluation system with schistosomiasis elimination criteria set by the Ministry of Health of Oman.Methods:Parasitological and serological assessments were carried out on population(mainly children)living in the area at risk for schistosomiasis in Dhofar,the country’s only endemic Governorate,for a period of over 30 years.Kato-Katz thick smear and Indirect Haemagglutination Assay were the techniques employed.Results:Data indicate a progressive decline in prevalence of S.mansoni throughout the 1980s and the 1990s,a recrudescence in the early 2000s,and a more marked decrease following the implementation of six rounds of mass treatment with praziquantel from 2007 to 2013.Latest parasitological prevalence(2011)was 0%,while latest serological prevalence(2014)was 0.11%.Conclusion:Transmission of schistosomiasis has reached very low levels in Oman.Elimination criteria established by the Ministry of Health of Oman(parasitological prevalence≤1%and serological prevalence≤5%)have been met since 2008.Further investigations are required to assess whether interruption of transmission has been achieved in some or all foci,in view of the establishment of a formal verification process under the auspices of WHO.
