1,311 research outputs found

    Wetting of grain boundaries in ultrafine-grained copper by liquid bismuth

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    In the present work, we studied the effect of liquid Bi on the microstructure evolution of ultrafinegrained Cu at elevated temperatures

    Missed Opportunities to Improve the Health of Postpartum Women: High Rates of Untreated Hypertension in Rural Tanzania

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    Objectives To assess the prevalence of high blood pressure amongst postpartum women in rural Tanzania, and to explore factors associated with hypertension prevalence, awareness, treatment, and control. Methods 1849 women in Tanzania’s Pwani Region who delivered a child in the prior year participated in the study. We measured blood pressure, administered a structured questionnaire and assessed factors associated with the prevalence, awareness, treatment, and control of hypertension (HTN) using bivariable and multivariable logistic regressions. Findings 26.7% of women had high blood pressure and/or were taking antihypertensive medication. Women were on average 27.5 years old (range 15–54). Nearly all women (99.5%) reported contact with the health system during their pregnancy and delivery, with an average of 5.2 visits for their own care in the past year. Only 23.5% of those with HTN were aware of their diagnosis, 17.4% were taking medication, and only 10.5% had controlled blood pressure. In multivariable analysis, facility delivery, health insurance, and increased distance from a hospital were associated with increased likelihood of HTN awareness; facility delivery and hospital distance were associated with current hypertensive treatment; younger age and increased hospital distance were associated with control of HTN. Conclusion The prevalence of high blood pressure in this postpartum population was high, and despite frequent recent contacts with the health system, awareness, treatment and control of HTN were low. These findings highlight an important missed opportunity to improve women’s health during antenatal and postnatal care

    Faceting of Twin Grain Boundaries in High-Purity Copper Subjected to High Pressure Torsion

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    Gradient bandgap narrowing in severely deformed ZnO nanoparticles

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    Gradient nanostructured metallic materials with a gradual change of grain boundary and dislocation density display unprecedent mechanical properties. Herein, we uncover a gradient of point defects concentration and concomitant gradient bandgap (E g) narrowing in metal oxide nanoparticles processed by a combination of severe shearing and frictional sliding deformation. Using the valence electron-energy loss spectroscopy technique, we find a gradual decrease of E g from 2.93 eV in the interior to 2.43 eV at the edge of the high-pressure torsion processed ZnO flake-shaped particle. This work paves the way to strain engineering of gradient-structured metal oxide semiconductors for unique functional properties

    Multi-wavelength Bragg coherent X-ray diffraction imaging of Au particles

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    International audienceMulti-wavelength (mw) Bragg coherent X-ray diffraction imaging (BCDI) is demonstrated on a single Au particle. The multi-wavelength Bragg diffraction patterns are inverted using conventional phase-retrieval algorithms where the dilation of the effective pixel size of a pixelated 2D detector caused by the variation of the X-ray beam energy is mitigated by interpolating the raw data. The reconstructed Bragg electron density and phase field are in excellent agreement with the results obtained from conventional rocking scans of the same particle. Voxel sizes of about 6 3 nm 3 are obtained for reconstructions from both approaches. Phase shifts as small as 0.41 rad, which correspond to displacements of 14 pm and translate into strain resolution better than 10 À4 in the Au particle, are resolved. The displacement field changes shape during the experiment, which is well reproduced by finite element method simulations considering an inhomogeneous strained carbon layer deposited on the Au particle over the course of the measurements. These experiments thus demonstrate the very high sensitivity of BCDI and mw-BCDI to strain induced by contaminations. Furthermore, mw-BCDI offers new opportunities for in situ and operando 3D strain imaging in complex sample environments
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