Synthesis and investigation of cobalt chalcogenide clusters with thienyl phosphine ligands as new acceptor materials for P3HT.

Cobalt selenide clusters with 2-bromo-5-diethylphosphinothiophene (1) and 2-bromo-5-diphenylphosphinothiophene (2) ligands are described. The phosphine ligands are obtained via lithium halogen exchange of 2,5-dibromothiophene followed by addition of chlorodiethylphosphine and chlorodiphenylphosphine, respectively. The prepared phosphine ligands are then sequentially reacted with elemental selenium followed by dicobalt octacarbonyl to yield Co6Se8(P(Et)2(C4H2SBr))6 (3) or Co6Se8(P(Ph)2(C4H2SBr))6 (4), respectively. The two new cobalt selenide clusters were characterized by UV-visible spectroscopy, Fourier-transform infrared spectroscopy, cyclic voltammetry, powder X-ray diffraction, and elemental analysis. Emission spectra were recorded for the addition of, Co6Se8(PEt3)6 (5), 3, and 4 to a 0.004 wt% solution of poly-3-hexyl thiophene (P3HT) in toluene to investigate the charge transport of the system. The quenching of the polymers' emission follows first-order like decay for each cluster. Clusters 3 and 4 are approximately twice as efficient at quenching the emission than cluster 5 with 4 being slightly more efficient than 3. Simple mixtures of 3, 4 or 5 and P3HT were spun cast from toluene into thin films and atomic force microscopy displayed relatively uniform dispersion of 3 and network-like formation of 4 in contrast to the phase separation of 5 in the polymer films.

The manganese stabilizing protein (MSP) and the control of O2 evolution in the unicellular, diazotrophic cyanobacterium, Cyanothece sp. ATCC 51142.

The unicellular diazotrophic cyanobacterium, Cyanothece sp. ATCC 51142 temporally separates N2 fixation from photosynthesis. To better understand the processes by which photosynthesis is regulated, we have analyzed Photosystem (PS) II O2 evolution and the PSII lumenal proteins, especially the Mn stabilizing protein (MSP). We describe a procedure using glycine betaine to isolate photosynthetic membranes from Cyanothece sp. that have high rates of PSI and PSII activity. Analysis with these membranes demonstrated similar patterns of O2 evolution in vivo and in vitro, with a trough at the time of maximal N2 fixation and with a peak in the late light period. The pattern of PSI activity was also similar in vivo and in vitro. We cloned the genes for MSP (psbO) and the 12 kDa protein (psbU) and analyzed their transcriptional properties throughout the diurnal cycle. We suggest that the changes in PSII activity in Cyanothece sp. were due to conformational changes in a highly flexible MSP, a suggestion which can now be studied in a chimera. The Cyanothece sp. psbO gene has been transformed into Synechocystis sp. PCC 6803; MSP and O2 evolution in the resulting transformant had properties that were similar to those in Cyanothece sp., providing additional confirmation for the properties of Cyanothece sp. MSP.

Remotely pollable Geiger-Müller detector for continuous monitoring of iodine-131 therapy patients.

UNLABELLED: In many countries, patients treated with therapeutic amounts of (131)I are hospitalized because of radiation safety considerations. To determine when they can return home, radiation levels are intermittently monitored at bedside using a handheld Geiger-MIller (GM) counter, although this procedure can be cumbersome and inexact. METHODS: We have developed and tested a remotely pollable system for continuous radiation monitoring of (131)I therapy inpatients, using readily available hardware and standard telephone lines. The remote detector system, consisting of a palmtop IBM-compatible personal computer, specialized software, PCMCIA modem and miniature serial port-based GM detector, is placed opposite the patient's bed at a fixed distance, and continuous 1-min acquisitions are started. Initially and at least twice daily, the remote palmtop is contacted by modem, and all interval data are uploaded onto the operator's base computer over the telephone line, including measurements taken with the patient in a predetermined standardized position. Continuous minute-to-minute data may be viewed in native form or can be imported into graphing and spreadsheet programs. Points acquired with the patient in standardized position are specially marked to highlight the constant geometry used. The ratio of initial counting rate to administered dose is used to estimate residual (131)I body burden by proportionality. Display of data as a semilogarithmic plot facilitates extrapolation of the activity curves and prediction of the patient's earliest time of discharge. RESULTS: We have characterized the remote GM detector system to confirm accuracy, counting rate linearity and reliability of data transfer. We describe examples that illustrate the applicability and usefulness of this method for remote monitoring of inpatient (131)I therapy levels. CONCLUSION: Monitoring patients with the described remotely pollable GM detector is an accurate and easy-to-implement technique that could conceivably lead to shortened hospital stays for (131)I therapy inpatients. Continuous quantitative data obtained are useful for kinetic and dosimetric analyses, which may be applied to study other gamma-emitting radiopharmaceuticals as well. The flexibility of the technique may permit its use in the monitoring of therapy on an outpatient basis, where allowed.

Sixth and eighth graders and acquired immunodeficiency syndrome: the results of focus group analysis.

OBJECTIVE: To determine young adolescents' range of factual knowledge and beliefs about human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) among those who have received AIDS education. DESIGN: Focus group analysis. SETTING: Urban middle school. PARTICIPANTS: Two male and two female groups consisting of 4-7 students each, ages 11-15 years. RESULTS: The predominant responses in all four groups relating to factual knowledge of HIV transmission and mechanisms of prevention were correct. However, responses indicated that factual information had not been integrated into students' plans for situations involving relationships and sexual activity. All four groups shared the image of AIDS as a disease of adults. The girls frequently gave responses which included discussion and use of condoms, whereas only a few boys could realistically visualize using condoms. Many students, predominantly boys, identified with media figures such as Magic Johnson and saw themselves to be at risk for HIV, but the girls almost exclusively saw Magic Johnson as a rich, famous person and did not identify with him. Students gave suggestions about ways to improve AIDS education and recommended that AIDS education begin in the early grades. CONCLUSION: Standard AIDS education may be effective in teaching factual information about AIDS, but it may have little effect on students' future behavior. The format of AIDS education may need to be modified to better address adolescents' beliefs and behaviors regarding HIV and AIDS.