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1.
Gastroenterol Hepatol ; 47(7): 774-792, 2024.
Artículo en Inglés, Español | MEDLINE | ID: mdl-38218430

RESUMEN

It is widely acknowledged that inflammatory bowel disease (IBD) is associated with a high prevalence of sexual dysfunction (SD). However, there is a notable paucity of specific literature in this field. This lack of information impacts various aspects, including the understanding and comprehensive care of SD in the context of IBD. Furthermore, patients themselves express a lack of necessary attention in this area within the treatment of their disease, thus creating an unmet need in terms of their well-being. The aim of this position statement by the Spanish Working Group on Crohn's Disease and Ulcerative Colitis (GETECCU) is to provide a review on the most relevant aspects and potential areas of improvement in the detection, assessment, and management of SD in patients with IBD and to integrate the approach to sexual health into our clinical practice. Recommendations are established based on available scientific evidence and expert opinion. The development of these recommendations by GETECCU has been carried out through a collaborative multidisciplinary approach involving gastroenterologists, gynecologists, urologists, surgeons, nurses, psychologists, sexologists, and, of course, patients with IBD.


Asunto(s)
Colitis Ulcerosa , Enfermedad de Crohn , Disfunciones Sexuales Fisiológicas , Humanos , Enfermedad de Crohn/complicaciones , Enfermedad de Crohn/terapia , Colitis Ulcerosa/complicaciones , Colitis Ulcerosa/terapia , Disfunciones Sexuales Fisiológicas/etiología , Disfunciones Sexuales Fisiológicas/terapia , España , Femenino , Masculino , Disfunciones Sexuales Psicológicas/etiología , Disfunciones Sexuales Psicológicas/terapia , Sexualidad , Enfermedades Inflamatorias del Intestino/complicaciones , Enfermedades Inflamatorias del Intestino/terapia , Salud Sexual
2.
Antioxidants (Basel) ; 12(12)2023 Dec 13.
Artículo en Inglés | MEDLINE | ID: mdl-38136224

RESUMEN

Inflammatory Bowel Diseases (IBD) are a group of chronic, inflammatory disorders of the gut. The incidence and activity of IBD are determined by both genetic and environmental factors. Among these factors, polymorphisms in genes related to autophagy and the consumption of non-steroidal anti-inflammatory drugs (NSAIDs) have been consistently associated with IBD. We show that NSAIDs induce mitochondrial stress and mitophagy in intestinal epithelial cells. In an altered mitophagy context simulating that observed in IBD patients, NSAID-induced mitochondrial stress leads to the release of mitochondrial components, which act as Danger Associated Molecular Patterns with pro-inflammatory potential. Furthermore, colonic organoids from Crohn's disease patients and healthy donors show activation of the mitochondrial Unfolded Protein Response (UPRmt) upon treatment with ibuprofen. Finally, colon biopsies from Crohn's disease patients in remission or with low-to-moderate activity also show expression of genes involved in UPRmt, while patients with severe activity show no increase compared to healthy donors. Our results suggest the involvement of mitochondria in the mechanisms triggering inflammation in IBD after NSAID use. Moreover, our results highlight the clinical relevance of mitochondrial stress and activation of the UPRmt pathway in the pathophysiology of Crohn's disease.

3.
J Cancer Surviv ; 14(5): 757-767, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32458248

RESUMEN

PURPOSE: We studied the influence of oncology and primary care provider (PCP) recommendations on caregiver intentions to restart vaccines (e.g., catch-up or boosters) after cancer treatment. METHODS: We surveyed primary caregivers ages 18 or older with a child who had completed cancer treatment 3-36 months prior (N = 145) about demographics, child's vaccination status, and healthcare factors (e.g., provider recommendations, barriers, preferences for vaccination). We compared these factors by caregiver's intention to restart vaccines ("vaccine intention" vs. "no intent to vaccinate") using bivariate and multivariable analyses. RESULTS: Caregivers were primarily ages 30-39 years (54.9%), mothers (80.6%), college graduates (44.4%), non-Hispanic (89.2%), and married (88.2%). Overall, 34.5% of caregivers did not know which vaccines their child needed. However, 65.5% of caregivers reported vaccine intention. Fewer caregivers with no intention to vaccinate believed that vaccinating their child helps protect others (85.4 vs. 99.0%, p < 0.01), that vaccines are needed when diseases are rare (83.7 vs. 100.0%, p < 0.01), and that vaccines are safe (80.4 vs. 92.6%, p = 0.03) and effective (91.5 vs. 98.9%, p = 0.04) compared with vaccine intention caregivers, respectively. Provider recommendations increased caregivers' likelihood of vaccine intention (oncologist RR = 1.65, 95% CI 1.27-2.12, p < 0.01; PCP RR = 1.51, 95% CI 1.19-1.94, p < 0.01). CONCLUSIONS: Provider recommendations positively influence caregivers' intention to restart vaccines after childhood cancer. Guidelines are needed to support providers in making tailored vaccine recommendations. IMPLICATIONS FOR CANCER SURVIVORS: Timely vaccination after childhood cancer protects patients against vaccine-preventable diseases during survivorship. Caregivers may benefit from discussing restarting vaccinations after cancer with healthcare providers.


Asunto(s)
Supervivientes de Cáncer/estadística & datos numéricos , Conocimientos, Actitudes y Práctica en Salud , Personal de Salud/psicología , Neoplasias/terapia , Pautas de la Práctica en Medicina/estadística & datos numéricos , Vacunación/estadística & datos numéricos , Vacunas/administración & dosificación , Adolescente , Adulto , Actitud del Personal de Salud , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Intención , Masculino , Persona de Mediana Edad , Encuestas y Cuestionarios , Vacunación/psicología , Adulto Joven
4.
Inorg Chem ; 59(9): 6595-6602, 2020 May 04.
Artículo en Inglés | MEDLINE | ID: mdl-32282189

RESUMEN

AmPO4 was prepared by a solid-state reaction method, and its crystal structure at room temperature was solved by powder X-ray diffraction combined with Rietveld refinement. The purity of the monazite-like phase was confirmed by spectroscopic (high-resolution solid-state 31P NMR and Raman) and microscopic (SEM-EDX and TEM) techniques. The thermal and self-irradiation stability have been studied. The compound is stable under argon and air atmosphere at least up to 1773 K. It remains crystalline under self-irradiation for circa two months, with a crystallographic volume swelling of ∼1.5%, and then is amorphizing over a year. However, microcrystals are present in the amorphous material even after a two year period of time. All these characteristics are discussed in relation to the potential application of AmPO4 as a stable form of Am in radioisotope power sources for space exploration and of behavior of the monazites under irradiation.

5.
J Pediatr Gastroenterol Nutr ; 71(2): 243-245, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32304559

RESUMEN

"The IBD Classroom in Nature" is an initiative that combines training and leisure activities in an ideal environment where families and patients can interact with each other. The objective of the present study was to quantify the effect that "The IBD Classroom in Nature" had on the health-related quality-of-life of patients with Inflammatory bowel disease (IBD). We conducted a prospective, analytical study with a pre-post design to demonstrate the impact on health-related quality-of-life (measured with the IMPACT-III questionnaire) of 3 days together in the context of The IBD Classroom in Nature. The study included 13 patients with IBD with a mean age of 12.3 years (interquartile range 11.9-14.5). After "The IBD Classroom in Nature" there was an improvement in the IMPACT-III score with significant improvements in the emotional functioning and body image domains. The present study objectively shows the beneficial effect of group activities focused on the most diverse aspects of their disease.


Asunto(s)
Colitis , Enfermedades Inflamatorias del Intestino , Niño , Humanos , Estudios Prospectivos , Calidad de Vida , Encuestas y Cuestionarios
6.
Solid State Nucl Magn Reson ; 105: 101638, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31810014

RESUMEN

We present the study of the phosphorus local environment by using 31P MAS NMR in a series of seven double monophosphates MIIMIV(PO4)2 (MII and MIV being divalent and tetravalent cations, respectively) of yavapaiite and low-yavapaiite type crystal structures. Solid-state and cluster DFT calculations were found to be efficient for predicting the 31P isotropic chemical shift and chemical shift anisotropy. To achieve this performance, however, a proper computational optimisation of the experimental structural data was required. From the three optimisation methods tested, the full optimisation provided the best reference structure for the calculation of the NMR parameters of the studied phosphates. Also, a better prediction of the chemical shifts was possible by using a correction to the GIPAW calculated shielding.

7.
Health Educ Res ; 34(4): 400-414, 2019 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-31329867

RESUMEN

Hispanics have the lowest colorectal cancer (CRC) screening rates of all racial/ethnic groups and comprise the largest proportion of low-income manual laborers in the nation. We partnered with businesses to implement a community health worker (CHW)-led intervention among Hispanic workers in service-related and manual labor occupations, which often pay low wages and do not provide health insurance. CHWs measured knowledge, screening adherence and perceptions of CRC risk before and after educational interventions via interview. CHWs provided fecal immunochemical tests (FITs) to participants aged ≥50 years. Chi-square tests and logistic regression identified pre-intervention predictors of CRC knowledge of all participants and adherence among eligible participants. Adherence among participants increased from 40% (n = 307) pre-intervention to 66% post-intervention. Knowledge about CRC was associated with age ≥50 years (OR = 8.90 [95% CI = 2.61-30.35]; ref = 18-30) and perceived personal risk for CRC (Likely, OR = 3.06 [95% CI = 1.40-6.67]; ref = Not likely). Insurance status was associated with screening adherence pre-intervention (OR = 3.00 [95% CI 1.10-8.12]; ref = No insurance). Improvement in adherence post-intervention was associated with income between $25 000 and ≥$55 000 (OR = 8.49 [95% CI 1.49-48.32]; ref = $5000-<$10 000). Community-based health programs can improve CRC screening adherence among Hispanic workers in service-related and manual labor positions, but lowest-income workers may need additional support.


Asunto(s)
Neoplasias Colorrectales/diagnóstico , Neoplasias Colorrectales/etnología , Detección Precoz del Cáncer , Hispánicos o Latinos , Tamizaje Masivo , Cooperación del Paciente/etnología , Pobreza , Adolescente , Adulto , Agentes Comunitarios de Salud , Femenino , Educación en Salud , Encuestas Epidemiológicas , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Sangre Oculta
8.
Inorg Chem ; 58(14): 9118-9126, 2019 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-31246454

RESUMEN

Both AmAlO3 and PuAlO3 perovskites have been synthesized and characterized using powder X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and 27Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR). AmAlO3 perovskite showed a rhombohedral configuration (space group R3̅c) in agreement with previous studies. The effect of americium α-decay on this material has been followed by XRD and 27Al MAS NMR analyses. In a first step, a progressive increase in the level of disorder in the crystalline phase was detected, associated with a significant crystallographic swelling of the material. In a second step, the crystalline AmAlO3 perovskite was progressively converted into amorphous AmAlO3, with a total amorphization occurring after 8 months and 2 × 1018 α-decays/g. For the first time, PuAlO3 perovskite was synthesized with an orthorhombic configuration (space group Imma), showing an interesting parallel to CeAlO3 and PrAlO3 lanthanide analogues. High-temperature XRD was performed and showed a Imma → R3̅c phase transition occurring between 473 and 573 K. The thermal behavior of R3̅c PuAlO3 was followed from 573 to 1273 K, and extrapolation of the data suggests that cubic plutonium perovskite should become stable at around 1850 K (R3̅c → Pm3̅m transition).

9.
J Community Health ; 44(2): 256-264, 2019 04.
Artículo en Inglés | MEDLINE | ID: mdl-30306449

RESUMEN

In the United States, Latinos are more likely to be uninsured and diagnosed with later stage cancer than non-Hispanic whites. Promotoras (lay health educators) help improve cancer knowledge and facilitate access to cancer screenings. We tested a promotora led workplace-based intervention to improve knowledge of and adherence to breast, cervical, and colorectal cancer screening among Latino employees in service or manual labor jobs. Latinos 18 and older from Salt Lake County, Utah were enrolled from January 2015 to February 2016. N = 265 completed pre- and post-intervention surveys that measured knowledge of and adherence to breast, cervical, and colorectal cancer screenings. Demographic, economic, and cancer factors of participants who completed the intervention were compared to those who were incomplete. Changes in knowledge and adherence were calculated using McNemar's tests. Logistic regression compared outcomes by select demographic, economic and cancer factors. More participants were older, spoke Non-English languages, were single/widow(er)s, worked part-time, and had an immediate family member with cancer compared to those who did not complete the study (all p < 0.05). Knowledge of the age to begin cancer screenings increased significantly from baseline to follow-up for cervical (65.1-77.7%), breast (67.2-81.7%), and colorectal cancer (49.8-80.7%), all p ≤ 0.001. Knowledge of the frequency of cervical (34.0-46.5%) and colorectal (72.1-84.5%) screening increased from baseline to follow-up, both p < 0.001. Adherence to fecal immunochemical tests (FIT) for colorectal cancer increased from baseline to follow-up (13.8-56.9%, p < 0.001). Promotora led workplace-based interventions can strengthen community capacity for educating and supporting Latino employees in preventing breast, cervical, and colorectal cancer.


Asunto(s)
Neoplasias de la Mama/prevención & control , Neoplasias Colorrectales/prevención & control , Detección Precoz del Cáncer/estadística & datos numéricos , Conocimientos, Actitudes y Práctica en Salud , Hispánicos o Latinos/estadística & datos numéricos , Neoplasias del Cuello Uterino/prevención & control , Adulto , Neoplasias de la Mama/etnología , Neoplasias Colorrectales/etnología , Empleo , Femenino , Promoción de la Salud/métodos , Hispánicos o Latinos/psicología , Humanos , Tamizaje Masivo , Pacientes no Asegurados/estadística & datos numéricos , Persona de Mediana Edad , Utah , Neoplasias del Cuello Uterino/etnología , Lugar de Trabajo
10.
Inorg Chem ; 57(24): 15350-15360, 2018 Dec 17.
Artículo en Inglés | MEDLINE | ID: mdl-30475605

RESUMEN

Because of its sensitivity to the atomic scale environment, solid-state NMR offers new perspectives in terms of structural characterization, especially when applied jointly with first-principles calculations. Particularly, challenging is the study of actinide-based materials because of the electronic complexity of the actinide cations and to the hazards due to their radioactivity. Consequently, very few studies have been published in this subfield. In the present paper, we report a joint experimental-theoretical analysis of thorium tetrafluoride, ThF4, containing a closed-shell actinide (5f0) cation. Its crystalline structure has been revisited in the present work using powder neutron diffraction experiments. The 19F NMR parameters of the seven F crystallographic sites have been modeled using an empirical superposition model, periodic first-principles calculations, and a cluster-based all-electron approach. On the basis of the atomic position optimized structure, a complete and unambiguous assignment of the 19F NMR resonances to the F sites has been obtained.

11.
J Community Health ; 43(4): 756-760, 2018 08.
Artículo en Inglés | MEDLINE | ID: mdl-29453619

RESUMEN

This pilot study aims to improve HPV vaccination for college aged males at a student health center. The first part of the study consisted of a focus group that assessed the barriers and facilitators of HPV vaccination among healthcare providers and clinic staff (N = 16). Providers reported missed opportunities for HPV vaccination. For the second part of the study, providers and staff reviewed medical records of patients ages 18-26 with student health insurance and with < 3 doses of the HPV vaccine at baseline (12/1/2014 to 7/31/2015) and follow-up (12/1/2015 to 7/31/2016). A computer-automated EMR alert was generated in the medical record of eligible male patients (N = 386). Z-scores were estimated for two-sample proportions to measure change in HPV vaccine rates at baseline and follow-up for males and females. HPV vaccine initiation rates increased among males (baseline: 5.2% follow-up: 25.1%, p < 0.001). This study shows that EMR alerts improved HPV vaccine initiation rates among insured college-aged males.


Asunto(s)
Registros Electrónicos de Salud/organización & administración , Infecciones por Papillomavirus/prevención & control , Vacunas contra Papillomavirus/administración & dosificación , Servicios de Salud para Estudiantes/organización & administración , Adolescente , Adulto , Humanos , Masculino , Salud del Hombre , Proyectos Piloto , Adulto Joven
12.
Inorg Chem ; 57(3): 1535-1544, 2018 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-29327923

RESUMEN

For nuclear fuel related applications, the oxygen stoichiometry of mixed oxides U1-yMyO2±x is an essential property as it affects fuel properties and may endanger the safe operation of nuclear reactors. A careful review of the open literature indicates that this parameter is difficult to assess properly and that the nature of the defects, i.e., oxygen vacancies or UV, in aliovalent cation-doped UO2 is still subject to controversy. To confirm the formation of UV, we have investigated the room-temperature stable U1-yLayO2±x phase using several experimental methods (e.g., XRD, XANES, and NMR) confirmed by theoretical calculations. This paper presents the experimental proof of UV and its effect we identified in both electronic and local structure. We observe that UV is formed in quasi-equimolar proportion as LaIII in U1-yLayO2±x (y = 0.06, 0.11, and 0.22) solid solutions. The fluorite structure is maintained despite the cationic substitution, but the local structure is affected as variations of the interatomic distances are found. Therefore, we provide here the definitive proof that the substitution of UIV with LaIII is not accommodated by the creation of O vacancies as has often been assumed. The UO2 fluorite structure compensates the incorporation of an aliovalent cation by the formation of UV in quasi-equimolar proportions.

13.
Sci Rep ; 7(1): 12269, 2017 09 25.
Artículo en Inglés | MEDLINE | ID: mdl-28947745

RESUMEN

The detailed characterization of local order and disorder in isometric A2B2O7 crystalline pyrochlores is of significant importance in view of their wide range and sensitive technological applications. Nevertheless, much remains to be understood concerning their atomic scale structures. Here we specifically pinpoint local order and disorder in four stoichiometric Ln2Zr2O7 (Ln = La, Nd, Sm and Eu) pyrochlores using a combination of three standard easily available laboratory techniques: XRD, 17O solid-state MAS NMR and Raman spectroscopy. The evolution of the oxygen sub-lattice identifies specific features (extra 17O NMR signals and Raman bands) which undoubtedly reveal local oxygen order and disorder in these stoichiometric long range ordered crystalline pyrochlores. These results complete the understanding of the atomic scale in these stoichiometric pyrochlores necessitating the need for new microscopic structural models.

14.
J Community Health ; 42(5): 911-920, 2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28393294

RESUMEN

PURPOSE: Rural and highly religious Intermountain West states demonstrate low levels of HPV vaccination uptake. The Intermountain West HPV Vaccination Coalition (IWHVC) was formed to improve HPV vaccination by enhancing collaborations between cancer centers, health departments, health clinics, religious groups, and community organizations. Coalition members' perceptions and experiences are described within. METHODS: A cross-sectional online survey was distributed to the IWHVC. N = 86 responded to the online survey. Six subsequent focus groups were conducted (N = 36). Participant demographics, barriers, and facilitators of HPV vaccination were summarized. The first three focus groups were coded in an iterative manner based on a coding scheme. The final three focus groups were selectively coded for content related to five themes: barriers and facilitators to HPV vaccination, how the coalition has been useful, future directions of the coalition, and how to engage religious communities. RESULTS: Participants suggested that HPV vaccination should occur in a doctor's office (70.9%), public health clinic (64.0%), or at a community health fair (58.1%). Perceived barriers included a lack of education/low knowledge about the HPV vaccine (55.8%), concerns about sexuality/promiscuity (44.2%), and not knowing the vaccine is recommended for boys (38.4%). Participants stressed the importance of gaining buy-in from religious leaders, and felt the coalition helped them advocate for HPV vaccination through networking, idea and information sharing, and voicing their community's needs. Future goals emphasized targeted outreach, sustainable funding, expanded environmental scans, gaining religious support, and policy reforms. CONCLUSIONS: Targeted coalition work builds community capacity and coordinates HPV vaccination efforts. A community driven coalition approach could help improve HPV vaccination in other rural and highly religious regions.


Asunto(s)
Educación en Salud , Infecciones por Papillomavirus/prevención & control , Vacunas contra Papillomavirus , Vacunación/estadística & datos numéricos , Adulto , Estudios Transversales , Femenino , Grupos Focales , Educación en Salud/métodos , Educación en Salud/organización & administración , Accesibilidad a los Servicios de Salud , Humanos , Masculino , Persona de Mediana Edad , Noroeste de Estados Unidos , Religión , Población Rural , Sudoeste de Estados Unidos
15.
Cienc. enferm ; 22(3): 77-84, set. 2016. tab
Artículo en Español | LILACS | ID: biblio-839757

RESUMEN

Objetivo: Conocer la asociación entre el nivel socioeconómico que presentaban los pacientes diagnosticados de dolor crónico que acudían a la Unidad del Dolor y su adaptación al dolor crónico en términos de dolor, discapacidad y estado de ánimo. Material y método: Se realizó un estudio correlacional con una muestra de pacientes con dolor crónico que acudían a la Unidad del Dolor del Hospital Carlos Haya de Málaga. Mediante el uso de autoinformes que fueron administrados de forma oral, se midieron las siguientes variables: el nivel socioeconómico, el dolor, la discapacidad y el estado de ánimo. Se aplicó un ANOVA para comparar a los pa cientes en función del nivel socioeconómico (NSE). Resultados: El grupo NSE bajo, formado mayoritariamente por mujeres (85,7%), presentaban un dolor más incapacitante para las actividades de la vida diaria y consumían más medicación. Conclusión: Los resultados revelan que las condiciones socioeconómicas pueden suponer un factor de riesgo de una experiencia más desadaptativa del dolor crónico.


Objective: To determine the association between the socioeconomic status of patients diagnosed with chronic pain entering the Pain Unit and their adaptation to chronic pain in terms of pain, disability and mood. Method: This is a cross-sectional study of 133 chronic pain patients attending the Pain Unit at the Carlos Haya Hospital in Málaga. By means of oral self-reports the following variables were measured: socioeconomic level, pain and discomfort, disability and mood. An ANOVA test was used to compare patients according to their Socioeconomic Status (SES). Results: The low SES group had more disabling pain for daily activities and took more medication. The low NSE group consisted mainly of women (85.7%). Conclusion: The results reveal that socioeconomic conditions may be a risk factor for more disabling chronic pain.


Asunto(s)
Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Anciano , Anciano de 80 o más Años , Dolor Crónico/epidemiología , Dolor Crónico/psicología , Clínicas de Dolor , Adaptación Psicológica , Afecto , Análisis de Varianza , Dolor Crónico/enfermería , Evaluación de la Discapacidad , Distribución por Sexo , Clase Social , Factores Socioeconómicos , Encuestas y Cuestionarios
16.
Sci Rep ; 6: 25499, 2016 05 05.
Artículo en Inglés | MEDLINE | ID: mdl-27149700

RESUMEN

Safe management of high level nuclear waste is a worldwide significant issue for which vitrification has been selected by many countries. There exists a crucial need for improving our understanding of the ageing of the glass under irradiation. While external irradiation by ions provides a rapid simulation of damage induced by alpha decays, short lived actinide doping is more representative of the reality. Here, we report radiological NMR experiments to compare the damage in International Simplified Glass (ISG) when irradiated by these two methods. In the 0.1 mole percent (244)Cm doped glass, accumulation of high alpha decay only shows small modifications of the local structure, in sharp contrast to heavy ion irradiation. These results reveal the ability of the alpha particle to partially repair the damage generated by the heavy recoil nuclei highlighting the radiation resistance of nuclear glass and the difficulty to accurately simulate its behaviour by single ion beam irradiations.

17.
Inorg Chem ; 54(11): 5358-65, 2015 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-25984750

RESUMEN

Uranium-plutonium mixed oxide containing 30% of plutonium is a candidate fuel for several fast neutron and accelerator driven reactor systems. In this work, a detailed structural investigation on sol-gel synthesized stoichiometric U0.7Pu0.3O2.00 and substoichiometric U0.7Pu0.3O2-x, using X-ray diffraction (XRD), oxygen 17 magic angle spinning nuclear magnetic resonance ((17)O MAS NMR) and X-ray absorption spectroscopy is described. As observed by XRD, the stoichiometric U0.7Pu0.3O2.00 is monophasic with a lattice parameter in good agreement with Vegard's law, while the substoichiometric U0.7Pu0.3O2-x material is biphasic. Solid solution ideality in terms of a random distribution of metal atoms is proven for U0.7Pu0.3O2.00 with (17)O MAS NMR. X-ray absorption near-edge structure (XANES) spectroscopy shows the presence of plutonium(III) in U0.7Pu0.3O2-x. Extended X-ray absorption fine-structure (EXAFS) spectroscopy indicates a similar local structure around both cations, and comparison with XRD indicates a close similarity between uranium and plutonium local structures and the long-range ordering.

18.
Inorg Chem ; 54(7): 3552-61, 2015 Apr 06.
Artículo en Inglés | MEDLINE | ID: mdl-25798917

RESUMEN

The crystal structure of trisodium uranate, which forms following the interaction between sodium and hyperstoichiometric urania, has been solved for the first time using powder X-ray and neutron diffraction, X-ray absorption near-edge structure spectroscopy, and solid-state (23)Na multiquantum magic angle spinning nuclear magnetic resonance. The compound, isostructural with Na3BiO4, has monoclinic symmetry, in space group P2/c. Moreover, it has been shown that this structure can accommodate some cationic disorder, with up to 16(2)% sodium on the uranium site, corresponding to the composition α-Na3(U1-x,Nax)O4 (0 < x < 0.18). The α phase adopts a mixed valence state with the presence of U(V) and U(VI). The two polymorphs of this compound described in the literature, m- and ß-Na3(U1-x,Nax)O4, have also been investigated, and their relationship to the α phase has been established. The completely disordered low-temperature cubic phase corresponds to a metastable phase. The semiordered high-temperature ß phase is cubic, in space group Fd3̅m.

19.
Inorg Chem ; 53(13): 6928-33, 2014 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-24926812

RESUMEN

A massive interest has been generated lately by the improvement of solid-state magic-angle spinning (MAS) NMR methods for the study of a broad range of paramagnetic organic and inorganic materials. The open-shell cations at the origin of this paramagnetism can be metals, transition metals, or rare-earth elements. Actinide-bearing compounds and their 5f unpaired electrons remain elusive in this intensive research area due to their well-known high radiotoxicity. A dedicated effort enabling the handling of these highly radioactive materials now allows their analysis using high-resolution MAS NMR (>55 kHz). Here, the study of the local structure of a series of actinide dioxides, namely, ThO2, UO2, NpO2, PuO2, and AmO2, using solid-state (17)O MAS NMR is reported. An important increase of the spectral resolution is found due to the removal of the dipolar broadening proving the efficiency of this technique for structural analysis. The NMR parameters in these systems with numerous and unpaired 5f electrons were interpreted using an empirical approach. Single-ion model calculations were performed for the first time to determine the z component of electron spin on each of the actinide atoms, which is proportional to the shifts. A similar variation thereof was observed only for the heavier actinides of this study.

20.
Solid State Nucl Magn Reson ; 45-46: 1-10, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22591998

RESUMEN

Dipolar-Heteronuclear Multiple Quantum Correlation (D-HMQC) experiment based on SR4(2)(1) recoupling was shown as a very efficient probe of spatial proximities in ordered or disordered materials. As crystalline sodium silicates have been extensively studied using 1D and 2D MAS NMR experiments and DFT calculations, they have been used as candidate model systems to perform this D-HMQC experiment. In this work, we demonstrate that the combination of (29)Si and (23)Na NMR at high magnetic field and DFT calculations makes it possible to revisit the assignment of the NMR signature of the δ-Na(2)Si(2)O(5) polymorph. A D-HMQC experiment performed on this crystalline sample reveals lineshape distortions on the (23)Na powder patterns extracted from the 2D correlation. Numerical simulations showed that these distortions result from an effect of the relative orientation between the (23)Na quadrupolar tensor and the (23)Na-(29)Si dipolar vector at the origin of the magnetization transfer.

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