RESUMO
Photosystem I (PSI) achieves photo-induced charge separation with outstanding internal quantum efficiency and has been used to improve the performance of various photoelectrochemical systems. Herein, we describe a fast and versatile technique to assemble composite films containing PSI and a chosen intrinsically conductive polymer (ICP). A mixture of PSI and a Friedel-Crafts catalyst (FeCl3) is drop cast atop a substrate of choice. Contact with ICP monomer vapor at low temperature stimulates polymer growth throughout PSI films in minutes. We assess the effects of PSI loading on the rapid vapor-phase growth of poly(3,4-ethylenedioxythiophene) (PEDOT) within and above PSI multilayer films, and characterize the resulting film's thickness, electrochemical capacitance, and photocatalytic response. Composite films generate cathodic photocurrent when in contact with an aqueous redox electrolyte, confirming retention of the photocatalytic activity of the polymer-entrapped PSI multilayer assembly.
RESUMO
A prostate cancer screening study of 315 asymptomatic men comparing digital rectal examination and transrectal ultrasound identified 23 cancers, for a detection rate of 7.3%. Of the cancers 17 (5.4%) were diagnosed by digital rectal examination. Contrary to the experience of others, this was a higher rate than achieved by transrectal ultrasound (14 cases or 4.4%). Systematic multiple needle biopsies of both lobes with ultrasound guidance were routinely performed. As a result of this technique 7 of 23 cancers (30%) were fortuitously diagnosed. In addition, only unilateral disease was suspected in 4 of 7 patients with bilateral disease on biopsy. Digital rectal examination and transrectal ultrasound identified the same number of patients with small (less than 1.5 cm.) cancers, contrary to other reports that found transrectal ultrasound to be superior. Digital rectal examination is considered an effective screening examination, equivalent to transrectal ultrasound and preferable because of lower cost. An algorithm for screening is outlined with digital rectal examination and prostate specific antigen determinations.
