Application of amorphous carbon based materials as antireflective coatings on crystalline silicon solar cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)We report on the investigation of the potential application of different forms of amorphous carbon (a-C and a-C:H) as an antireflective coating for crystalline silicon solar cells. Polymeric-like carbon (PLC) and hydrogenated diamond-like carbon films were deposited by plasma enhanced chemical vapor deposition. Tetrahedral amorphous carbon (ta-C) was deposited by the filtered cathodic vacuum arc technique. Those three different amorphous carbon structures were individually applied as single antireflective coatings on conventional (polished and texturized) p-n junction crystalline silicon solar cells. Due to their optical properties, good results were also obtained for double-layer antireflective coatings based on PLC or ta-C films combined with different materials. The results are compared with a conventional tin dioxide (SnO(2)) single-layer antireflective coating and zinc sulfide/magnesium fluoride (ZnS/MgF(2)) double-layer antireflective coatings. An increase of 23.7% in the short-circuit current density, J(sc), was obtained using PLC as an antireflective coating and 31.7% was achieved using a double-layer of PLC with a layer of magnesium fluoride (MgF(2)). An additional increase of 10.8% was obtained in texturized silicon, representing a total increase (texturization + double-layer) of about 40% in the short-circuit current density. The potential use of these materials are critically addressed considering their refractive index, optical bandgap, absorption coefficient, hardness, chemical inertness, and mechanical stability. (C) 2011 American Institute of Physics. [doi:10.1063/1.3622515]1104Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Brazilian financial research agency MCTConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Prevalence of asymptomatic urethritis by Chlamydia trachomatis and Neisseria gonorrhoeae and associated risk factors among males living with HIV-1

ABSTRACT Objectives The increase in HIV transmissibility in non-ulcerative sexually transmitted infection is already well-established. It is estimated that symptomatic carriers of N. gonorrhoeae and C. trachomatis have a relative risk of 4.8-fold and 3.6-fold, respectively, for the sexual acquisition of HIV. This type of evaluation for asymptomatic urethritis is necessary to reinforce strategies to combat HIV transmission. This study aims to assess the prevalence of patients with asymptomatic urethritis among men diagnosed with HIV-1 and determine the risk factors associated with this infection. Methods We enrolled a total of 115 male patients aged 18 years or older who have been diagnosed with HIV infection and have no symptoms of urethritis or other sexually transmitted infections and who have been evaluated between May and August 2015 in a follow-up visit at the Immunology Outpatient Clinic of a Brazilian University Hospital. Results Four asymptomatic patients were positive for C. trachomatis and were considered asymptomatic carriers of urethritis. Prevalence was 3.47%. Patients who were positive for C. trachomatis urethritis had a lower mean age (p = 0.015). Conclusion The presence of asymptomatic sexually transmitted infection is a challenge in clinical practice. We recommend that, in outpatient practice, the habit of inquiring on previous sexual behavior to obtain more information about risks and associations with asymptomatic sexually transmitted infection, a routine physical examination and complementary tests to detect STI pathogens should be performed to discard these conditions. The development of rapid tests for this purpose should also be encouraged

Optical polarimetry: Methods, Instruments and Calibration Techniques

In this chapter we present a brief summary of methods, instruments and calibration techniques used in modern astronomical polarimetry in the optical wavelengths. We describe the properties of various polarization devices and detectors used for optical broadband, imaging and spectropolarimetry, and discuss their advantages and disadvantages. The necessity of a proper calibration of the raw polarization data is emphasized and methods of the determination and subtraction of instrumental polarization are considered. We also present a few examples of high-precision measurements of optical polarization of black hole X-ray binaries and massive binary stars made with our DiPol-2 polarimeter, which allowed us to constrain the sources of optical emission in black hole X-ray binaries and measure orbital parameters of massive stellar binaries.Comment: 33 pages, 14 figure; to be published in Astrophysics and Space Science Library 460, Astronomical Polarisation from the Infrared to Gamma Ray