Optical and electrical properties of porous gallium arsenide

Photoluminescence (PL), Raman scattering, and carrier transport have been studied for the first time in porous GaAs prepared on (111) oriented wafers of n-type crystalline GaAs (faces A and B). Peaks of the main PL band from faces A and B were observed at 1.82 and 1.88 eV, respectively. The electron drift mobility was found to be ～4×10^?4 cm² V^?1 s^?1. The nanocrystallite size in porous GaAs was determined both from PL spectra and from the Raman shift. The obtained values are close or equal to 6–8 nm.     

Cover Image,Volume 98, Issue 10

The cover image, by Vessela Kancheva et al., is based on the Research Article Protective effects of new antioxidant compositions of 4‐methylcoumarins andrelated compounds with DL‐α‐tocopherol and L‐ascorbic acid, DOI: 10.1002/jsfa.8892 .

     

Spheroid Formation and Peritoneal Metastasis in Ovarian Cancer: The Role of Stromal and Immune Components

Ovarian cancer (OC) is one of the most common gynecological cancers, with the worst prognosis and the highest mortality rate. Peritoneal dissemination (or carcinomatosis) accompanied by ascites formation is the most unfavorable factor in the progression and recurrence of OC. Tumor cells in ascites are present as either separate cells or, more often, as cell aggregates, i.e., spheroids which promote implantation on the surface of nearby organs and, at later stages, metastases to distant organs. Malignant ascites comprises a unique tumor microenvironment; this fact may be of relevance in the search for new prognostic and predictive factors that would make it possible to personalize the treatment of patients with OC. However, the precise mechanisms of spheroid formation and carcinomatosis are still under investigation. Here, we summarize data on ascites composition as well as the activity of fibroblasts and macrophages, the key stromal and immune components, in OC ascites. We describe current knowledge about the role of fibroblasts and macrophages in tumor spheroid formation, and discuss the specific functions of fibroblasts, macrophages and T cells in tumor peritoneal dissemination and implantation.     

Modification of the electrical and optical properties of hydrated vanadium pentoxide as a result of proton electromigration

Variation of the optical and electrical properties of films of hydrated vanadium pentoxide under the action of an applied electric field was studied. The samples exhibited an “internal” electrochromic effect caused by a redistribution of hydrogen ions in the film, rather than by their penetration from outside (electrolyte). The process of cathodic polarization at a current of I～10^?5 A for t～10 min is accompanied by a local increase in the hydrogen concentration (confirmed by direct measurements of the ionic conductivity), leading to a change in the optical properties. This is manifested by an increase in the transmission coefficient in the longwave spectral region and by a shift of the absorption edge (at hν=2.3 eV) toward greater wavelengths. According to the IR spectroscopy data, this is also accompanied by some increase in the water content in colored regions of the V₂O₅·nH₂O film.