Commensurate-Incommensurate Magnetic Phase Transition in Magnetoelectric Single Crystal LiNiPO4_4

Neutron scattering studies of single-crystal LiNiPO$_4$ reveal a spontaneous first-order commensurate-incommensurate magnetic phase transition. Short- and long-range incommensurate phases are intermediate between the high temperature paramagnetic and the low temperature antiferromagnetic phases. The modulated structure has a predominant antiferromagnetic component, giving rise to satellite peaks in the vicinity of the fundamental antiferromagnetic Bragg reflection, and a ferromagnetic component giving rise to peaks at small momentum-transfers around the origin at $(0,\pm Q,0)$. The wavelength of the modulated magnetic structure varies continuously with temperature. It is argued that the incommensurate short- and long-range phases are due to spin-dimensionality crossover from a continuous to the discrete Ising state. These observations explain the anomalous first-order transition seen in the magnetoelectric effect of this system

Étude par diffraction des rayons X des vernis rouges des sigillées du sud de la Gaule. Les ateliers de la Graufesenque

La Graufesenque (Millau, Aveyron) 1$^{\rm rst}$ and 2$^{\rm nd}$, centuries AC Sigillata red slips have been studied by x-ray diffraction at ESRF and on a conventional diffractometer. Although x-ray diffraction is a non-destructive characterisation technique adapted to surface study, it has not been used so mutch for Sigillata slip characterisation. The poor quality of the slip surface can be an explanation. In this work we demonstrate that it is possible to get good quality diffraction diagrams on 20-120 AC Sigillata slips. The results confirm the productions homogeneity and the hypothesis about a non-local clay used for the slips. On a counterpart, the late (second half of 2$^{\rm nd}$ century AC) Sigillata study needs because of their crackled surface a high quality beam, which can only be accessible on a synchrotron installation. These productions seems to be more heterogeneous: some Sigillata present similar diffraction diagrams for the slip and ceramic body (same clay?), some others present results similar to the precedent production period ones.Les vernis rouges de poteries sigillées (I$^{\rm er}$ et II$^{\rm e}$ siècles) de la Graufesenque (Millau, Aveyron) ont été étudiés par diffraction des rayons X à la fois à l'ESRF et sur une installation classique de laboratoire. Bien que la diffraction des rayons X soit une technique adaptée à l'étude des surfaces, cette technique a jusqu'à présent assez peu servi dans l'examen de ces objets. Ceci peut en partie s'expliquer par le mauvais état de surface de certains vernis. Dans ce travail, nous montrons que moyennant quelques précautions, il est possible d'obtenir sur une installation classique de bons diffractogranunes des vernis des sigillées datés entre 20 et 120 ap. J.C. Les résultats confirment l'homogénéité de ces productions et l'hypothèse selon laquelle ces vernis n'ont pas été fabriqués à partir des argiles locales du jurassique environnant le site. Par contre, l'étude des sigillées tardives de la deuxième moitié du II$^{\rm e}$ siècle, dont les vernis sont très écaillés, nécessite une qualité de faisceau inaccessible sur une installation classique, et ne peut être réalisée que sur une source de lumière de type synchrotron. Ces productions semblent plus hétérogènes : certaines sigillées tardives ont un vernis qui pourrait avoir été élaboré à partir de l'argile locale, tandis que d'autres ont encore le vernis des sigillées de la période précédente

Metal nanoparticles in contemporary potters’ master pieces: Lustre and red “pigeon blood” potteries as models to understand the ancient pottery

International audienceReduction of metal precursors within the molten glaze is a rather complex route to obtain coloured glaze. " Sang de boeuf " , " pigeon blood " or " flammé" first discovered glazes by the Chinese potters of the Song Dynasty (10 th c.) are produced by atmosphere controlled firing of copper-containing glaze on porcelain and stoneware body. Lustre pottery, an Abbasid potters' innovation (9 th c.), offers to the eyes of the connoisseur an iridescent reflection, which is only visible at specular position. For centuries connoisseurs' interest in these objects has been continuous and the development of transmission electronic microscopy (TEM) associated with energy-dispersive X-ray spectroscopy (TEM-EDX) allows us an in depth study of the micro and nano-structure of these objects. A porcelain with red " pigeon blood " decor made by the late famous French-American potter Fance Franck, and lustre stonewares made by the French potter Eva Haudum, have been investigated by TEM-EDX and nanochemical analysis in order to better understand the key parameters controlling the microstructure and the colour of glazes. Although some authors assigned the red colour of pigeon-blood to Cu 2 O, our results clearly demonstrate that the colour only arises from Cu° nanoparticles. Phase separation of the glassy phase was observed close to the surface. Concerning the lustrewares, analysis confirmed that the alternating reducing and oxidizing conditions during the firing lead well to the formation of metal-free/metal-rich alternate layers in the lustre decor

Prevalence of metabolic syndrome in patients menopausal

El síndrome metabólico implica la asociación en un mismo individuo de dislipidemia, Diabetes Mellitus 2 o intolerancia a la glucosa, hipertensión arterial y exceso de peso u obesidad. La resistencia a la insulina juega un papel central en la génesis de este síndrome y se considera causante del inicio del proceso de aterosclerosis. Esto sumado a la pérdida del efecto protector de los estrógenos durante la menopausia puede llevar a la formación de placa ateromatosa y secundariamente el desarrollo de la enfermedades cardiocerebro vasculares y sus posibles secuelas. El objetivo del presente trabajo es determinar la prevalencia de síndrome metabólico en las pacientes menopáusicas y posibles factores relacionados, mediante un Estudio de tipo corte transversal, a través de la revisión de historias clínicas de las pacientes que acudieron a la consulta de Ginecología Endocrinológica en el Hospital Militar Central entre el 13 de marzo de 2013 y el 31 de diciembre de 2014. Resultados: En total 81 mujeres menopáusicas fueron incluidas en el estudio. La media de edad fue de 58.6 ± 10.3 años. El promedio de edad de la última regla fue de 10.3 años. La prevalencia de síndrome metabólico fue del 23.5%. Se encontró antecedente personal de Hipertensión arterial en 44.4%, Diabetes Mellitus en 25.6%, Hipercolesterolemia en 60.0% e Hipertrigliceridemia en 46.9% de los casos. También se documentó que 50% presentan niveles de HDL <50mg/dl, 46.9% triglicéridos ≥150mg/dl, 44.4% tensión arterial ≥130/85mmHg, 25.6% glicemia 100mg/dl y 22.2% IMC ≥30. Se evidenció que el 82.7% de las pacientes presentan algún tipo de dislipidemia como diagnóstico final. El 59.2% de la población estudiada presentan sobrepeso y obesidad, de las cuales el 35.8% presentan sobrepeso y el 23.4% obesidad. El análisis bivariado en busca de factores de riesgo mostró una diferencia estadísticamente significativa con el estrato socioeconómico <3 (p = 0.011), antecedente familiar de hipertensión arterial (p = 0.117) y de Diabetes Mellitus (p = 0.157). De acuerdo al modelo multivariado final, la variable que aumentan el riesgo de síndrome metabólico fue el estrato socioeconómico (OR 4.7; IC 95% 1.03 – 22.11). En conclusión el síndrome metabólico es una enfermedad de presentación alta en pacientes menopáusicas, con mayor riesgo en pacientes de estrato socioeconómico bajo y antecedente de patologías de base con HTA y diabetes mellitus que facilitan la instauración del mismo, por lo que estas pacientes se benefician de intervenciones tempranas y un manejo multidisciplinario para la prevención de enfermedades cardiovasculares secundarias al mismo.Metabolic syndrome involves the association in the same individual of dyslipidemia, Diabetes Mellitus 2 or glucose intolerance, hypertension and overweight or obese. The insulin resistance plays a central role in the genesis of this syndrome and to be causing the start of the process of atherosclerosis. This coupled with the loss of the protective effect of estrogen during menopause can lead to the formation of atheromatous plaque and secondly the development of vascular diseases cardiocerebro and its possible consequences. The aim of this study was to determine the prevalence of metabolic syndrome in postmenopausal patients and possible related factors, using a cross-sectional study type, through review of medical records of patients who attended the Gynecological Endocrinology in Central Military hospital between March 13, 2013 and December 31, 2014. Results: A total of 81 postmenopausal women were included in the study. The mean age was 58.6 ± 10.3 years. The average age of the last menstrual period was 10.3 years. The prevalence of metabolic syndrome was 23.5%. Personal history of arterial hypertension in 44.4%, 25.6% diabetes mellitus, hypercholesterolemia and hypertriglyceridemia in 60.0% was found in 46.9% of cases. Was also documented that 50% have levels of HDL <50mg / dl, triglycerides 46.9% ≥150mg / dl, 44.4% blood pressure ≥130 / 85mmHg, 25.6% glucose 100 mg / dl and 22.2% BMI ≥30. It showed that 82.7% of patients have some type of dyslipidemia as a final diagnosis. 59.2% of the study population were overweight or obese, of which 35.8% were overweight and 23.4% obese. The bivariate analysis in search of risk factors showed a statistically significant difference with socioeconomic <3 strata (p = 0.011), family history of hypertension (p = 0.117) and diabetes mellitus (p = 0.157). According to the final multivariate model, the variable that increase the risk of metabolic syndrome was socioeconomic status (OR 4.7, 95% CI 1.03 - 22.11). In conclusion, the metabolic syndrome is a disease of high presentation menopausal patients with increased risk in patients of low socioeconomic status and history of underlying conditions with hypertension and diabetes mellitus that facilitate the establishment of the same, so these patients benefit from early interventions and a multidisciplinary approach for the prevention of cardiovascular disease secondary to it

Polarization-optical observation of ferroelastic domains in the incommensurate phase of BaMnF 4

The 1st direct observation by means of polarized light microscopy of the ferroelastic domains of the incommensurate phase (av. monoclinic symmetry) of BaMnF4 is reported