Optoelectronic properties of natural cyanin dyes.

An integrated theoretical/experimental study of the natural cyanin dye is presented in terms of its structural and optoelectronic properties for different gas-phase and prototypical device configurations. Our microscopic analysis reveals the impact of hydration and hydroxylation reactions, as well as of the attached sugar, on ground and optically excited states, and it illustrates the visible-light harvesting capability of the dye. Our optical experiments at different and controlled pH concentrations allow for a direct comparison with theoretical results. We analyze the many different contributions to photocurrent of the various portions of a prototypical device and, as a proof of principle, we propose the addition of specific ligands to control the increase of the photocurrent yield in the cyanin-based electrochemical device.

Invasive group A streptococcal infections in a large tertiary center: epidemiology, characteristics and outcome.

BACKGROUND: Invasive group A streptococcal (GAS) infections are increasing alarmingly worldwide. PATIENTS AND METHODS: To determine the clinical and epidemiologic characteristics of invasive GAS in a large tertiary medical center, we retrospectively surveyed microbiology and medical records of patients with invasive GAS infections (isolation of Group A Streptococcus from a normally sterile site) treated in our hospital from January 1995 to December 1997. RESULTS: 70 patients with a median age of 48 years (range 2 months-88 years) were identified. Of the 70 identified, 53 (76%) were adults (age > or = 19 years). The most common co-morbid diseases for invasive GAS in adults were diabetes mellitus, congestive heart failure (CHF), malignancy and immunosuppression. A probable port of entry was identified in 31 (44%) of the cases. In children, varicella lesions were the major port of entry. Overall mortality rate was 17%: The difference in mortality between pediatric and adult cases was significant (0/17 vs 12/53, respectively; p = 0.03). Toxic shock syndrome (TSS) and necrotizing fasciitis were identified in 8.6% and 5.7% of the cases, respectively, with mortalities of 83.3% and 25%. Hyponatremia and hypocalcemia were more frequently observed among the severely ill. CONCLUSION: Invasive GAS infections tend to have an unexpected course and a broad clinical spectrum, ranging from local skin or pharyngeal involvement to deeply invasive fasciitis with TSS and high mortality. The elderly and those with underLying medical conditions are at utmost rsk for invasive GAS. Clear-cut guidelines for early therapeutic strategy, i.e. antibiotic administration and preemptive hospital admission are needed for community-based physicians.