RESUMO
In this study, the influence of the TiCl(4) post-treatment on nanocrystalline TiO(2) films as electrodes in dye-sensitized solar cells is investigated and compared to nontreated films. As a result of this post-treatment cell efficiencies are improved, due to higher photocurrents. On a microscopic scale TiO(2) particle growth on the order of 1 nm is observed. Despite a corresponding decrease of BET surface area, more dye is adsorbed onto the oxide surface. Although it seems trivial to match this finding with the improved photocurrent, this performance improvement cannot be attributed to higher dye adsorption only. This follows from comparison between incident photon to current conversion efficiency (IPCE) and light absorption characteristics. Since the charge transport properties of the TiO(2) films are already more than sufficient without treatment, the increase in short circuit current density J(SC) cannot be related to improvements in charge transport either. Transient photocurrent measurements indicate a shift in the conduction band edge of the TiO(2) upon TiCl(4) treatment. It is concluded that the main contribution to enhanced current originates from this shift in conduction band edge, resulting in improved charge injection into the TiO(2).
RESUMO
An ocular status survey of the Samburu tribe of Kenya was carried out. There were 844 survey members in an age and sex stratified cluster sample. The prevalence of those who were found to have moderate visual loss or worse (less than 20/60 [6/18] in the better eye) was 3.8%. Those blind by USA criteria represented 1.7% of the total population. The two principal causes of blindness, cataract and corneal opacity, are both surgically amenable. A description of the Samburu people, the survey methods, and a summary of the survey findings are included.
Assuntos
Cegueira/etiologia , Catarata/complicações , Opacidade da Córnea/complicações , Adolescente , Adulto , Cegueira/epidemiologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Quênia , Masculino , Pessoa de Meia-IdadeRESUMO
A comparative retrospective study was performed on 39 patients with open-angle glaucoma in whom the right eye was subjected to Scheie's operation, the left to trabeculectomy. Trabeculectomy without the use of additional therapy or reoperation brought the intraocular pressure to under 22 mmHg in 80% of the cases compared with 74% treated by Scheie's operation. Reduction of visual acuity postoperatively was 4 times more frequent with Scheie's operation than with trabeculectomy. A report on a second group of patients in whom 47 trabeculectomies were performed is also given.
Assuntos
Glaucoma/cirurgia , Adulto , Idoso , Feminino , Glaucoma/fisiopatologia , Humanos , Pressão Intraocular , Iris/cirurgia , Quênia , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/epidemiologia , Esclera/cirurgia , Malha Trabecular/cirurgia , Acuidade VisualAssuntos
Colo Sigmoide/cirurgia , Derivação Urinária , Criança , Pré-Escolar , Creatinina/sangue , Eletrólitos/sangue , Feminino , Seguimentos , Humanos , Lactente , Masculino , Potássio/metabolismo , UrografiaRESUMO
Follow-up of 13 children who had had a ureterosigmoid anastomosis 3 1/2 to 10 years previously and whose initial urogram had been satisfactory, showed that growth was normal and that there was no serious metabolic disorder. In particular whole-body potassium did not differ significantly from normal values (as given by Langham, 1961). Asymptomatic urinary infection is the chief hazard in these cases but is difficult to diagnose and may lead to progressive dilatation of the ureters.