Optical spectroscopy of Nd ions in a nanostructured glass matrix

This paper presents the optical characterization of Nd³⁺ ions in nanostructured SiO₂-Na₂CO₃-Al₂O₃-B₂O₃ (SNAB) CdS glass, synthesized by fusion. Radiative properties of the glass were determined by absorption, luminescence spectroscopy and lifetime measurements. Nd³⁺ emission enhancement and quenching were investigated in the presence of CdS nanocrystals. Nd³⁺-emission quenching was attributed to upconversion mechanisms and nonradiative processes such as multiphonon decay and energy transfer, while the Nd³⁺-emission enhancement was due to energy transfer from the CdS nanocrystals. Changes in the chemical environment around CdS nanocrystals were also confirmed by Judd-Ofelt calculations.     

High Quantum Efficiency of Nd3+ Ions in a Phosphate Glass System using the Judd–Ofelt Theory

The optical properties of trivalent neodymium embedded in a P₂O₅–Al₂O₃–Na₂O–K₂O phosphate glass system, synthesized by the fusion method, are studied. Absorption, luminescence, lifetime, and Raman spectroscopy measurements were performed and the Judd–Ofelt theory was applied to determine optical parameters such as the quantum efficiency and the stimulated emission cross section of the Nd³⁺-doped glass system. This structure has high quantum efficiency at low Nd³⁺ concentrations, comparable to the efficiency of a commercial YAG:Nd³⁺ crystal. We discuss the mechanisms responsible for the high quantum efficiency observed in the proposed phosphate glass system.     

Effects of angiotensin II receptor blockers in the coronary arteries of hypertensive rats: Analysis of elemental distribution using LEXRF

Hypertension is one of the major public health problems worldwide. It can cause severely alterations in artery structure and function such as vascular remodeling. Angiotensin II (Ang II) has been linked to vascular dysfunction. It has been shown that blockade of the Ang II type 1 receptor with an Ang II receptor blocker (ARBs) may reverse vascular pathology independently of blood pressure lowering. There is therefore a special interest in establishing whether antihypertensive treatment may correct in part or completely the structural and functional alterations of arteries. Several studies have shown regression of structural remodeling or of functional alterations of small arteries in spontaneously hypertensive rats (SHR) treated with ARBs agents. However, its efficiency was not verified at elemental level in the literature. Knowledge of the elemental distribution in tissues has a great importance in the study of diseases, because chemical imbalance can alter biological functions. Elemental semiquantitative microanalysis in the coronary artery of normotensive, SHRs, and SHRs rats treated with ARBs (losartan and olmesartan) was performed using low energy X-ray fluorescence maps acquired on TwinMic X-ray spectromicroscopy station, located at the Elettra synchrotron radiation facility. Morphological changes in coronary samples were also investigated. The results demonstrate that despite the antihypertensive agents used belong to the same class, their capacities to revert chemical and structural changes in the coronary arteries caused by hypertension are different.