Structural and elastic properties of defect chalcopyrite HgGa2S4 under high pressure

In this work, we focus on the study of the structural and elastic properties of mercury digallium sulfide (HgGa2S4) at high pressures. This compound belongs to the family of AB(2)X(4) ordered-vacancy compounds and exhibits a tetragonal defect chalcopyrite structure. X-ray diffraction measurements at room temperature have been performed under compression up to 15.1 GPa in a diamond anvil cell. Our measurements have been complemented and compared with ab initio total energy calculations. The axial compressibility and the equation of state of the low-pressure phase of HgGa2S4 have been experimentally and theoretically determined and compared to other related ordered-vacancy compounds. The pressure dependence of the theoretical cation-anion and vacancy-anion distances and compressibilities in HgGa2S4 are reported and discussed in comparison to other related ordered-vacancy compounds. Finally, the pressure dependence of the theoretical elastic constants and elastic moduli of HgGa2S4 has been studied. Our calculations indicate that the low-pressure phase of HgGa2S4 becomes mechanically unstable above 13.8 GPa. (C) 2013 Elsevier B. V. All rights reserved.This study was supported by the Spanish government MEC under Grants No: MAT2010-21270-C04-01/03/04 and CTQ2009-14596-C02-01, by the Comunidad de Madrid and European Social Fund (S2009/PPQ-1551 4161893), by MALTA Consolider Ingenio 2010 Project (CSD2007-00045), by Generalitat Valenciana (GVA-ACOMP-2013-1012), and by the Vicerrectorado de Investigacion y Desarrollo of the Universidad Politecnica de Valencia (UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11). E.P-G., A. M., and P.R-H. acknowledge computing time provided by Red Espa ola de Supercomputacion (RES) and MALTA-Cluster. J.A.S. acknowledges Juan de la Cierva fellowship program for financial support.Gomis Hilario, O.; Santamaría-Pérez, D.; Vilaplana Cerda, RI.; Luna Molina, R.; Sans, JA.; Manjón Herrera, FJ.; Errandonea, D.... (2014). Structural and elastic properties of defect chalcopyrite HgGa2S4 under high pressure. Journal of Alloys and Compounds. 583:70-78. https://doi.org/10.1016/j.jallcom.2013.08.123S707858

Electronic structure, linear, nonlinear optical susceptibilities and birefringence of CuInX2 (X = S, Se, Te) chalcopyrite-structure compounds

The electronic structure, linear and nonlinear optical properties have been calculated for CuInX2 (X=S, Se, Te) chalcopyrite-structure single crystals using the state-of-the-art full potential linear augmented plane wave (FP-LAPW) method. We present results for band structure, density of states, and imaginary part of the frequency-dependent linear and nonlinear optical susceptibilities. We find that these crystals are semiconductors with direct band gaps. We have calculated the birefringence of these crystals. The birefringence is negative for CuInS2 and CuInSe2 while it is positive for CuInTe2 in agreement with the experimental data. Calculations are reported for the frequency-dependent complex second-order non-linear optical susceptibilities . The intra-band and inter-band contributions to the second harmonic generation increase when we replace S by Se and decrease when we replace Se by Te. We find that smaller energy band gap compounds have larger values of in agreement with the experimental data and previous theoretical calculations.Comment: 17 pages, 6 figure

Lattice dynamics study of HgGa2Se4 at high pressures

We report on Raman scattering measurements in mercury digallium selenide (HgGa2Se4) up to 25 GPa. We also performed, for the low-pressure defect-chalcopyrite structure, lattice-dynamics ab initio calculations at high pressures which agree with experiments. Measurements evidence that the semiconductor HgGa2Se4 exhibits a pressure-induced phase transition above 19 GPa to a previously undetected structure. This transition is followed by a transformation to a Raman-inactive phase above 23.4 GPa. On downstroke from 25 GPa until 2.5 GPa, a broad Raman spectrum was observed, which has been attributed to a fourth phase, and whose pressure dependence was followed during a second upstroke. Candidate structures for the three phases detected under compression are proposed. Finally, we also report and discuss the decomposition of the sample by laser heating at pressures close to 19 GPa. As possible products of decomposition, we have identified at least the formation of trigonal selenium nanoclusters and cinnabar-type HgSe.This study was supported by the Spanish government MEC under Grant No. MAT2010-21270-004-01/03/04, by MALTA Consolider Ingenio 2010 project (CSD2007-00045), by Generalitat Valenciana through project GVA-ACOMP-2013-012, and by the Vicerrectorado de Investigacion y Desarrollo of the Universidad Politecnica de Valencia (UPV2011-0966 and UPV2011-0914). E.P.-G., J.L.-S., A.M., and P.R.-H. acknowledge computing time provided by Red Espanola de Super-computacion (RES) and MALTA-Cluster.Vilaplana Cerda, RI.; Gomis Hilario, O.; Manjón Herrera, FJ.; Ortiz, HM.; Pérez González, E.; López Solano, J.; Rodríguez Hernández, P.... (2013). Lattice dynamics study of HgGa2Se4 at high pressures. Journal of Physical Chemistry C. 117(30):15773-15781. https://doi.org/10.1021/jp402493rS15773157811173

Protocolo de estudo para a utilização da técnica seldi tof ms (surface-enhanced laser desorption/ionizatio time-of-flight mass spectrometry), no rastreamento de biomarcadores circulantes no sangue de doadores de órgãos para transplante de pâncreas

Introduction: pancreas-kidney simultaneous transplantation is the only capable method to maintaining an euglycemia prolonged state in a type 1 diabetic patients who attend with renal failure. However, this procedure is associated with a high mortality rate due to postoperative complications and early loss of pancreatic and kidney grafts. The main cause of pancreatic graft failure, is the consequent loss cause technical dysfunction, suffering and graft thrombosis, commonly associated with clinical and biological characteristics of organ donors, as well as cellular acute rejection. By the time, donor organs criteria for selection is based on age, the serum sodium value, vasoactive drugs use and the hemodynamic changes during the capture, also the serum creatinine levels, is used to assessment of renal function. These changes characteristics are well known, that related the quality of grafts for transplantation and probably reflect a systemic metabolic and protein profile of the donor at the time of supply the organs for transplants, which has not yet been determined or associated with functioning grafts . Objectives: To present a study protocol identyfing systemic proteomic profiles of organ donors, relating it to the clinical criteria and comparing this profile to the clinical outcome of recipients of these grafts. Methods: 31 different donors, blood samples of different organs were analyzed in the state of São Paulo, subjecting them to proteomic analysis using the technique SELDI-TOF-MS (Surface Enhanced Laser Desorption-/ Ionization Time-Of-Flight Mass Spectrometry), evaluating 41 different analytes (cytokines and chemokines) standardized by HCYTOMAG KIT-60K-PX29 / PX30-HCYTMAG-60K / 60K-HCYTMAG-PX38 / PX41 HCYTMAG-60K-Milliplex®, determining in this way these donors profile, tabulating this information later to establish a large-scale 48 comparison of these profiles, with clinical data from donors and recipients and the evolution of the respective organs. Results: The IL4, IL10, IL 13, IL 1b, IL 9, IL 2 and TNF ?, showed very low doses of all 31 samples. Interleukins SDC40L, eotaxin, IP 10, MCP 1, RANTES, MDC, and IL 6, unlike the previous ones, were very high in all samples. Conclusions: This study showed that it was possible to establish a proteomic profile of donor organs that can lead to a comparative analysis with the clinical data of donors and the results of the receptors, indicating a new prevention line against adverse events, mostly related to rejection and the survival of grafts and recipients.O transplante simultâneo pâncreas-rim é o único método capaz de manter um estado prolongado de euglicemia nos doentes diabéticos tipo 1 que cursam com insuficiência renal. No entanto, este procedimento está associado a uma alta taxa de mortalidade devido às complicações pós-operatórias e à perda precoce dos enxertos pancreáticos e renais. A principal causa de falência os enxertos pancreáticos é a perda técnica consequente à disfunção, ao sofrimento e à trombose do enxerto, comumente associadas às características clínicas e biológicas dos doadores de órgãos, bem como rejeição celular aguda. Até o momento são utilizados critérios para escolha dos doadores de órgãos baseados na iadade, no valor do sódio sérico, no uso de drogas vasoativas, nas alterações hemodinâmicas no momento da captação e na avaliação da função renal através dos níveis de creatinina sérica. Estas características bem conhecidas são alterações que estão relacionadas à qualidade dos enxertos para transplante e, provavelmente, refletem um perfil metabólico e proteico sistêmico dos doadores, no momento da oferta de órgãos para transplantes, que ainda não foi determinado ou associado com o funcionamento dos enxertos. Objetivos: Apresentar um protocolo de estudo para identificar perfis proteômicos sistêmicos dos doadores de órgãos, relacionando-o com os critérios clínicos e comparando este perfil à evolução clínica dos receptores destes enxertos. Métodos: Foram analisadas 31 amostras de sangue de diferentes doadores de órgãos diferentes, no estado de São Paulo, submetendo-as às análises proteômica, através da técnica SELDI-TOF-MS (Surface-Enhanced Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry), avaliando 41 analitos diferentes (citocinas e quimiocinas) padronizados pelo KIT HCYTOMAG-60K-PX29/HCYTMAG-60K- xii PX30/HCYTMAG-60K-PX38/HCYTMAG-60K-PX41 Milliplex?, determinando, dessa maneira, o perfil desses doadores, tabulando essas informações, para posteriormente estabelecer em larga escala uma comparação desses perfis com os dados clínicos dos doadores e com a evolução dos receptores dos respectivos órgãos. Resultados: Nota-se que a IL4, IL10, IL 13, IL 1b, IL 9, IL 2 e TNF ?, apresentaram dosagens muito baixas em todas as 31 amostras. As Interleucinas SDC40L, EOTAXINA, IP 10, MCP 1, RANTES, IL 6 e MDC, ao contrário das anteriores, estiveram muito elevadas em todas as amostras. Conclusões: este estudo mostrou que foi possível estabelecer um perfil proteômico dos doadores de órgãos que poderá contribuir para uma análise comparativa com os dados clínicos dos doadores e com os resultados dos receptores, indicando uma nova linha de prevenção de eventos adversos, principalmente relacionados a rejeição e a sobrevida dos enxertos e dos receptores.Dados abertos - Sucupira - Teses e dissertações (2013 a 2016