Band gap engineering and photoluminescence tuning in halide double perovskites.

Halide double perovskites (HDPs) present a convenient alternative to the unstable and toxic lead halide perovskites for various optoelectronic applications. Because of their compositional and structural tunability, many HDP phases have been synthesized in the past decades. While efficient photovoltaic applications remain largely out of reach for the HDP phases due to their wide band gaps and structures with pseudoisolated metal centers, their electronic structures favor light conversion applications. Since the field of HDP witnesses rapid growth and development, this article is aimed at providing a brief snapshot of the recent advances on all-inorganic HDPs, primarily focusing on the relationship between their compositions and optical properties, and some aspects of their applications for visible light conversion.

U(V) Stabilization via Aliovalent Incorporation of Ln(III) into Oxo-salt Framework.

Pentavalent uranium compounds are key components of uranium's redox chemistry and play important roles in environmental transport. Despite this, well-characterized U(V) compounds are scarce primarily because of their instability with respect to disproportionation to U(IV) and U(VI). In this work, we provide an alternate route to incorporation of U(V) into a crystalline lattice where different oxidation states of uranium can be stabilized through the incorporation of secondary cations with different sizes and charges. We show that iriginite-based crystalline layers allow for systematically replacing U(VI) with U(V) through aliovalent substitution of 2+ alkaline-earth or 3+ rare-earth cations as dopant ions under high-temperature conditions, specifically Ca(UVIO2)W4O14 and Ln(UVO2)W4O14 (Ln=Nd, Sm, Eu, Gd, Yb). Evidence for the existence of U(V) and U(VI) is supported by single-crystal X-ray diffraction, high energy resolution X-ray absorption near edge structure, X-ray photoelectron spectroscopy, and optical absorption spectroscopy. In contrast with other reported U(V) materials, the U(V) single crystals obtained using this route are relatively large (several centimeters) and easily reproducible, and thus provide a substantial improvement in the facile synthesis and stabilization of U(V).

Phosphorescence in Mn4+-Doped R+/R2+ Germanates (R+ = Na+ or K+, R2+ = Sr2+).

Single crystals of three new compounds, Na0.36Sr0.82Ge4O9 (1, proposed composition), Na2SrGe6O14 (2), and K2SrGe8O18 (3), were obtained and characterized using single-crystal X-ray diffraction. Their structures contain three-dimensional (3D) anionic frameworks built from GeO4 and GeO6 polyhedra. The presence of octahedral Ge4+ sites makes the new phases suitable for Mn4+ substitution to obtain red-emitting phosphors with a potential application for light conversion. Photoluminescence properties of Mn4+-substituted Na2SrGe6O14 (2) and K2SrGe8O18 (3) samples were studied over a range of temperatures, and red light photoluminescence associated with the electronic transitions of tetravalent manganese was observed. The Na2SrGe6O14 (2) phase was also substituted with Pr3+ on the mixed Na-Sr site similar to the previously studied Na2CaGe6O14:Pr3+. The red emission peak of the Pr3+ activator occurs at a shorter wavelength (610 nm) compared to that of Mn4+ (662-663 nm). Additionally, second harmonic generation (SHG) data were collected for the noncentrosymmetric Na2SrGe6O14 (2) phase, indicating weak SHG activity. Diffuse reflectance spectroscopy and density of states calculations were performed to estimate the band gap values for pristine Na2SrGe6O14 (2) and K2SrGe8O18 (3) phases.

Alternative ways to optimize treatment for retinal vein occlusion with peripheral capillary non-perfusion: a pilot study.

PURPOSE:: We compared the efficacy and safety of ranibizumab versus ranibizumab plus scatter laser photocoagulation (SLP) in patients with chronic post-central retinal vein occlusion (CRVO) macular edema (ME). METHODS:: This prospective non-randomized pilot study included 250 patients with peripheral retinal ischemia and CRVO-related ME. The mean follow-up period was 24.5 ± 6.5 months. The clinical assessments conducted included best corrected visual acuity, optical coherence tomography, and multi-field fluorescein angiography with measurement of the ischemic area. The study population comprised two comparable patient groups with peripheral retinal ischemia that received different treatments for post-CRVO ME: ranibizumab with peripheral SLP of capillary non-perfusion areas (Group 1); and Lucentis® monotherapy (Group 2). Data analyses were performed using Statistica 7 software suite and included the estimation of х ± δ values and their dispersion and covariation coefficients at different stages of the study. RESULTS:: Clinically significant retinal ischemia was detected in 175 (70%) patients, occupying an average of 435.12 ± 225.13 mm2, i.e., 167.15 ± 45.16 optic disc areas. Peripheral ischemia was found in 125 patients, representing 50% of all patients with CRVO and 71.4% of all patients with ischemic CRVO. The mean number of ranibizumab injections in patients who underwent SLP was 3.5 ± 1.6. Patients treated with ranibizumab monotherapy for 24 months received 10.6 ± 2.5 injections. Functional and anatomic results were comparable in the two groups. CONCLUSIONS:: The combination of ranibizumab injections and peripheral SLP in capillary non-perfusion areas can significantly decrease the number of injections and reduce neovascular complications.

Alternative ways to optimize treatment for retinal vein occlusion with peripheral capillary non-perfusion: a pilot study / Opções alternativas para otimizar o tratamento da oclusão da veia retiniana sem perfusão capilar periférica (um estudo piloto)

ABSTRACT Purpose: We compared the efficacy and safety of ranibizumab versus ranibizumab plus scatter laser photocoagulation (SLP) in patients with chronic post-central retinal vein occlusion (CRVO) macular edema (ME). Methods: This prospective non-randomized pilot study included 250 patients with peripheral retinal ischemia and CRVO-related ME. The mean follow-up period was 24.5 ± 6.5 months. The clinical assessments conducted included best corrected visual acuity, optical coherence tomography, and multi-field fluorescein angiography with measurement of the ischemic area. The study population comprised two comparable patient groups with peripheral retinal ischemia that received different treatments for post-CRVO ME: ranibizumab with peripheral SLP of capillary non-perfusion areas (Group 1); and Lucentis® monotherapy (Group 2). Data analyses were performed using Statistica 7 software suite and included the estimation of х ± δ values and their dispersion and covariation coefficients at different stages of the study. Results: Clinically significant retinal ischemia was detected in 175 (70%) patients, occupying an average of 435.12 ± 225.13 mm2, i.e., 167.15 ± 45.16 optic disc areas. Peripheral ischemia was found in 125 patients, representing 50% of all patients with CRVO and 71.4% of all patients with ischemic CRVO. The mean number of ranibizumab injections in patients who underwent SLP was 3.5 ± 1.6. Patients treated with ranibizumab monotherapy for 24 months received 10.6 ± 2.5 injections. Functional and anatomic results were comparable in the two groups. Conclusions: The combination of ranibizumab injections and peripheral SLP in capillary non-perfusion areas can significantly decrease the number of injections and reduce neovascular complications.

RESUMO Objetivo: A investigação centra-se na terapia de edema macular pós-oclusão da veia retiniana central (OVCR) em casos com isquemia retiniana periférica. O objetivo foi comparar a eficácia e a segurança do tratamento com ranibizumab vs ranibizumab + fotocoagulação com laser de dispersão (SLP) em pacientes com edema macular crônico secundário a oclusão da veia retiniana central isquêmica. Métodos: O estudo prospectivo não-randomizado incluiu 250 pacientes com isquemia retiniana periférica e edema macular relacionados a oclusão da veia retiniana central. O tempo médio de seguimento foi de 24,5 ± 6,5 meses. A avaliação clínica incluiu acuidade visual melhor corrigida, tomografia de coerência óptica (OCT) e angiografia por fluoresceína multi-campo com a medição da área de isquemia. A população estudada foi constituída por dois grupos de pacientes comparáveis com o oclusão da veia retiniana central isquêmica, que receberam tratamento diferente. Em nossa prática anterior, utilizamos ranibizumab (Lucentis®) em monoterapia (de acordo com a licença do medicamento) para edema macular pós-oclusão da veia retiniana central com isquemia retiniana periférica (Grupo 2). Mais recentemente, começamos a combinar ranibizumab com SLP periférica de áreas não perfusão capilar (Grupo 1). As análises de dados foram realizadas com o software Statistica 7 e incluíram a estimação dos valores de х ± δ e seus coeficientes de dispersão e covariân cia em diferentes estágios do estudo. Resultados: Identificou-se isquemia retiniana clinicamente significativa em 175 (70%) pacientes, atingindo uma média de 435,12 ± 225,13 mm2, ou seja, 167,15 ± 45,16 áreas de disco óptico. Isquemia periférica foi encontrada em 125 casos, representando 50% de todos os pacientes com oclusão da veia retiniana central e 71,4% de todos os pacientes com oclusão da veia retiniana central isquêmica. O número médio de injeções de rani bizumab em pacientes com SLP foi de 3,5 ± 1,6. Os pacientes tratados com ranibizu mab em monoterapia durante 24 meses receberam 10,6 ± 2,5 injeções. Os resultados funcionais e anatômicos foram comparáveis nos dois grupos. Conclusões: A combinação de injeções de ranibizumab com SLP periférica em áreas de não-perfusão capilar pode diminuir significativamente o número de injeções e reduzir as complicações neovasculares.