Phase behaviour of PMMA-b-PHEMA with solvents methanol and THF: modelling and comparison to the experiment.

Self-consistent field theory is used to model the self-assembly of a symmetric PMMA-block-PHEMA in the presence of two solvents, methanol and tetrahydrofuran (THF). The model predictions are compared to our experimental results of solvent-vapour annealing of thin polymer films, where the sequence of cylinder to gyroid (or micelles) to lamellar phases was found upon increasing the methanol-THF ratio and for particular extents of film swelling. The Hansen solubility parameters are used to estimate the Flory-Huggins interaction parameters (χ) needed in the theoretical model. However, because enacting the experimental range of high (χ)N values is computationally prohibitive, the use of moderate (χ)N values is compensated by employing larger values of the solvent-to-polymer size ratio (α). This approach is validated by showing that the predicted phase diagrams exhibit qualitatively similar trends whether (χ)N or α is increased. Using such an approach, the theory predicts a cylinder to gyroid to lamellar transition on increasing the THF-methanol ratio, a trend consistent with that observed in the experiments.

Enhanced diastolic filling performance with lifelong physical activity in aging mice.

PURPOSE: The purpose of this study was to investigate the age-related changes in diastolic filling parameters in the aging hearts of active C57Bl/6J mice throughout the life span to indicate optimal age periods for improvements in resting diastolic parameters. METHODS: Fourteen C57Bl/6J mice (seven males and seven females) were individually housed at 8 wk of age in cages with a running wheel, magnetic sensor, and digital odometer. Duration, distance, and running velocity were recorded daily. Fourteen additional mice C57Bl/6J mice (seven males and seven females) were placed in individual cages without running wheels at 8 wk of age. Pulsed-wave Doppler transmitral inflow recordings with a SONOS 5500 ultrasound and 15-6L ultrasound probe were used to image the left ventricle every 4 wk throughout the life span. RESULTS: Peak E wave filling velocities were significantly greater by the start of the second quarter of the life span in the mice with access to running wheels (P < 0.0001). Peak E wave velocities improved in both groups during the first half of the life span (P < 0.0001) and declined throughout the second half of the life span (P < 0.0001). Early-to-late (E:A) filling ratio was significantly greater for the physically active mice by the start of the second quarter of the life span (P < 0.0001) and continued throughout most of the remainder of the life span (P < 0.0001). No differences were observed between the two groups of mice with peak A wave filling velocities (P > 0.05). Similar findings were observed when corrected for resting heart rate. CONCLUSIONS: Lifelong physical activity resulted in greater diastolic filling parameters by the second quarter of the life span, highlighting the clinical importance of regular aerobic activity in young adulthood as a mechanism for improved left ventricular performance with aging.

Basal cell carcinoma: an infrequent pedal reality.

The authors intend to present a more detailed look at the basal cell carcinoma, both clinically and histologically. An in-depth treatment approach, case presentation, and literature review is provided in order to aid the practicing physician to better understand and treat this cutaneous malignancy. Through describing the variety of appearances of the basal cell carcinoma, the practitioner, hopefully, will be made more aware of the very real possibility of carcinoma in the differential diagnosis of dermatologic lesions.

In vivo and in vitro study of 48V uptake in developing rat molar enamel.

The uptake of 48V in developing rat molar enamel was studied in vivo and in vitro using autoradiographic and quantitative methods. It was shown that the uptake of 48V in enamel is less than in bone and dentin, and that plasma protein binding of 48V is primarily responsible for the limited uptake in enamel.