Synthesis of CaNb2O6 with a Rynersonite-like Structure: Morphology, Rietveld Refinement, Optical, and Vibrational Properties.

In this study, we report the easy and low-cost synthesis of calcium niobate (CaNb2O6) with the isomorphic structure of the Rynersonite mineral for CaTa2O6. The samples were prepared by the ball milling method at room temperature at a synthesis time of 0.5, 1, 2, 3, and 4 h. The structural analysis by XRD, Rietveld refinement, and vibrational Raman spectroscopy confirms all diffraction peaks and active mode characteristics of the pure phase of CaNb2O6 for the 3-h and 4-h samples, with a crystallite size of 22.5 and 23.2 nm, respectively. The optical band gap obtained was 3.18(2) eV (3-h sample), lower than the optical band gap for niobium oxide, characteristic of materials with strong photon absorption in the UVA region of the spectrum. The surface analysis by scanning electron microscopy reveals the obtention of several agglomerates of irregular particles ranging in the submicro and micro scales. Therefore, the present approach successfully obtained calcium niobate with the formula CaNb2O6 at a short synthesis time and room temperature.

[HIV/AIDS: expression of nursing students imaginary through photography]. / VIH/sida: Expresión del imaginario de los estudiantes de enfermería a través de a fotografía.

INTRODUCTION: Caring for people with HIV is an exercise of reflection and self-analysis in relation to our own beliefs about it. Along with the personal and social values, future nursing professional' beliefs have an important paper in the field of stigmatized diseases such as HIV infection, and may have an impact on nursing care. The aim of this study is to deeply know the meaning of the possibility of living with HIV among nursing students, bringing us a closer understanding of the subjective beliefs that give meaning to the act of caring. METHODOLOGY: Qualitative study with a phenomenological approach. Data collection was done through photographs and reflective stories. RESULTS: Living with HIV would change their lives, associating it to illness and fear of social rejection. Planning the future appears difficult, generating kind of uncertainty. However, some light of hope and social change is also observed. CONCLUSION: The possibility of acquiring HIV is lived as a negative experience associated with old fashioned experiences. It is necessary to facilitate forms of expression to visualize the internal processes of the opinions and invite discussion and permeation to other perspectives that may have an impact, direct or indirect, in nursing care.

Powder neutron diffraction of Tl2BeF4 at six temperatures from room temperature to 1.5 K.

The structure of thallium fluoroberyllate, Tl2BeF4, has been analysed by the Rietveld method on neutron diffraction patterns collected at 1.5, 50, 100, 150, 200 and 300 K, with the aim of detecting low-temperature instabilities. Atomic parameters based on the isomorphic beta-K2SO4 crystal in the paraelectric phase were used as the starting model at room temperature; no evidence for any phase transition has been detected at lower temperature. The structure was determined in the orthorhombic space group Pnma. All the atoms (except one F atom) occupy sites with m symmetry. We have compared the structure with those of other compounds of the beta-K2SO4 family, at room temperature, in order to gain insight into their observed instabilities. The irregular coordination of the cations may indicate stereochemical activity of the TlI lone pair but does not indicate a possible structural instability.