Application of PDF analysis assisted by MD simulations for determination of the atomic structure and crystal habit of CdSe nanocrystals

Structure of plate-shape nanodiamonds synthesized from chloroadamantane-are they still diamonds?

Atomic structure of plate-shaped nanodiamonds synthesized from chloroadamantane was identified with application of large-Qpowder diffraction data. Both reciprocal and real space methods of experimental data analysis were applied. Theoretical atomistic models of nanodiamonds were obtained with application of molecular dynamics (MD) simulations. It was found that examined nanodiamond samples with average grain size from 1.2 up to 2.5 nm are plates build from only six hexagonal carbon layers and they are terminated by (111)B surfaces with three dangling bonds. MD simulations showed that as a result of relaxation of surface stresses there appears a complex system of compressive and tensile strains across and parallel to the surface of the plate-nanodiamonds. Identification of the internal structure of nanodiamond was performed based on the analysis of differential interatomic distance diagrams derived from pair distribution functionsG(r). Based on MD simulations an atomic model of plate-grains of diamond was elaborated. Usefulness of lattice parameters determined in a routine diffraction data analysis for characterization of nanodiamonds is questioned. As an alternative the application of the apparent lattice parameter is recommended. A dependence of the overall apparent lattice parameter 〈alp〉 on the size and shape of nanodiamond grains terminated by low index crystal faces is presented.

Impacts of different methylprednisolone administration routes in patients with sudden hearing loss or Meniere's disease

BACKGROUND

Evidence suggests that glucocorticoids are important in the treatment of sudden hearing loss (SHL) and Meniere's disease (MD). However, different glucocorticoid administration methods may have a significant impact on treatment outcomes.

OBJECTIVE

This study aimed to investigate effects of different glucocorticoid administration methods on sudden hearing loss and Meniere's disease.

METHODS

In this study, glucocorticoids were administered orally in 18 patients, by retroauricular injection in 15 patients and by intratympanic injection in 15 patients. White blood cell (WBC) count, serum K+, fasting plasma glucose (FPG), body temperature, heart rate and blood pressure were used to evaluate effects of glucocorticoids on patients with hearing loss. Visual analog scale (VAS) of pain and sleep disorders were also surveyed, and pure tone audiometry (PTA) results were compared among groups to evaluate efficacy of different glucocorticoids administration methods.

RESULT

WBC count, heart rate and blood pressure were higher in patients taking oral glucocorticoids, while body temperature, serum K+ and FPG levels did not change in all three groups. However, patients who received intratympanic injection of glucocorticoids experienced more pain, while those taking oral glucocorticoids reported more sleep impairment. Treatment efficacy on hearing loss was not significantly different among the three groups.

CONCLUSION

These findings suggest that systemic glucocorticoid administration can result in greater whole body responses than local administration, but with similar hearing treatment efficacy.