Sintering behaviour of 3D-printed 18K 5N gold alloy by binder jetting: a preliminary study

Binder jetting is a versatile additive manufacturing technique suitable to produce alloys that are difficult to obtain by powder bed fusion techniques, such as precious metals, due to their high reflectivity and thermal conductivity. In this study, a 18K 5N gold alloy powder was employed in the printing process. Different heat treatments and densification processes were employed to achieve final-stage sintering and remove residual porosity, whilst controlling the evolution of copper oxides by reduction with hydrogen and graphite. Powder, green and sintered samples were characterised at the microstructural level by X-ray diffraction, microscopy and energy dispersive X-ray spectroscopy to assess phase transitions and secondary-phase formation. Oxide-free components with a final relative density above 90% were achieved by densification at 830 °C combined with carbon- and CO-induced reduction of tenorite and cuprite. The optimal manufacturing route was chosen to produce a bezel, as a case study for the adoption of this technique in the jewellery industry

Should reduction of increased short-term blood pressure variability be a target of antihypertensive therapy?

It has long been known that blood pressure (BP) is characterized by marked short-term fluctuations occurring within a 24-h period and also by long-term oscillations occurring over more prolonged periods of time. An increased short-term blood pressure variability (BPV) appears to importantly contribute to target organ damage and to the enhanced cardiovascular risk of hypertensive patients, over and above the effect of an increase in mean BP levels. Reducing 24-h mean BP is the main aim of antihypertensive therapy, but initial data are available that additional cardiovascular protection can be achieved by reducing BPV. However, to definitively prove the prognostic role of short-term BPV and the need for its control by treatment, evidence is still needed from intervention trials aimed at demonstrating that by reducing BPV through administration of antihypertensive drugs, a reduction in organ damage and in the rate of cardiovascular events can be obtained

Absence of an independent association between serum uric acid and left ventricular mass in Caucasian hypertensive women and men

Background and aim: Experimentally uric acid may induce cardiomyocyte growth and interstitial fibrosis of the heart. However, clinical studies exploring the relationship between serum uric acid (SUA) and left ventricular (LV) mass yielded conflicting results. The aim of our study was to evaluate the relationships between SUA and LV mass in a large group of Caucasian essential hypertensive subjects. Methods and results: We enrolled 534 hypertensive patients free of cardiovascular complications and without severe renal insufficiency. In all subjects routine blood chemistry, including SUA determination, echocardiographic examination and 24 h ambulatory blood pressure (BP) monitoring were obtained. In the overall population we observed no significant correlation of SUA with LV mass indexed for height2.7 (LVMH2.7) (r = 0.074). When the same relationship was analysed separately in men and women, we found a statistically significant correlation in female gender (r = 0.27; p < 0.001), but not in males (r = 0.042; p = NS). When we grouped the study population in sex-specific tertiles of SUA, an increase in LVMH2.7 was observed in the highest tertiles in women (44.5 \ub1 15.6 vs 47.5 16 vs 55.9 \ub1 22.2 g/m2.7; p < 0.001), but not in men. The association between SUA and LVMH2.7 in women lost statistical significance in multiple regression analyses, after adjustment for age, 24 h systolic BP, body mass index, serum creatinine and other potential confounders. Conclusions: Our findings do not support an independent association between SUA and LV mass in Caucasian men and women with arterial hypertension

Soil warming alters nitrogen cycling in a New England forest : implications for ecosystem function and structure

© The Author(s), 2011. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Oecologia 168 (2012): 819-828, doi:10.1007/s00442-011-2133-7.Global climate change is expected to affect terrestrial ecosystems in a variety of ways. Some of the more well-studied effects include the biogeochemical feedbacks to the climate system that can either increase or decrease the atmospheric load of greenhouse gases such as carbon dioxide and nitrous oxide. Less well-studied are the effects of climate change on the linkages between soil and plant processes. Here, we report the effects of soil warming on these linkages observed in a large field manipulation of a deciduous forest in southern New England, USA, where soil was continuously warmed 5°C above ambient for 7 years. Over this period, we have observed significant changes to the nitrogen cycle that have the potential to affect tree species composition in the long term. Since the start of the experiment, we have documented a 45% average annual increase in net nitrogen mineralization and a three-fold increase in nitrification such that in years 5 through 7, 25% of the nitrogen mineralized is then nitrified. The warming-induced increase of available nitrogen resulted in increases in the foliar nitrogen content and the relative growth rate of trees in the warmed area. Acer rubrum (red maple) trees have responded the most after 7 years of warming, with the greatest increases in both foliar nitrogen content and relative growth rates. Our study suggests that considering species-specific responses to increases in nitrogen availability and changes in nitrogen form is important in predicting future forest composition and feedbacks to the climate system.This work was supported by the National Institute for Climate Change Research (DOE-DE-FCO2-06-ER64157), DOE BER (DE-SC0005421) and the Harvard Forest Long-Term Ecological Research program (NSF-DEB-0620443)

Canes domésticos como reservorio de Leptospira spp y Toxoplasma gondii en una comunidad campesina del Bosque nuboso del noreste de Perú

The aim of this study was to identify the role of domestic dogs as reservoirs of Leptospira spp and Toxoplasma gondii in the Rural Community of Corosha, department of Amazonas, Peru, through the analysis of prevalence and epidemiological characteristics, as well as tenure associated with dog positivity. A survey was carried out on the dog owners and blood samples were taken. In total, 55 samples were analyzed by the Microscopic Agglutination Test (MAT) for the identification of anti-Leptospira spp antibodies and 62 samples with the Indirect Hemagglutination technique (HAI) for anti-T. gondii. The seroprevalence of Leptospira spp was 82.3%, detecting antibodies against the Grippotyphosa (58.2%), Icterohaemorrhagiae (54.6%), Pomona (40.0%), Canicola (32.7%), Bratislava (30.9%) and Georgia (21.8%) serovars. Dogs with access to the river showed a higher prevalence of Leptospira (94.9%) compared to individuals without access (68.8%) (p&lt;0.05). Likewise, 37.1% of the evaluated dogs were seropositive for T. gondii. The study reveals the circulation of Leptospira spp and T. gondii in domestic dogs of the rural community of Corosha.El objetivo del estudio fue identificar el rol de los canes domésticos como reservorios de Leptospira spp y Toxoplasma gondii en la Comunidad Campesina de Corosha, departamento de Amazonas, Perú, mediante el análisis de prevalencia y de las características epidemiológicas, así como de tenencia asociadas a la positividad de los canes. Se realizó una encuesta a los tutores de los canes y se tomaron muestras sanguíneas. En total, 55 muestras fueron analizadas por la Prueba de Aglutinación Microscópica (MAT) para la identificación de anticuerpos anti-Leptospira spp y 62 muestras con la técnica de Hemaglutinación Indirecta (HAI) para anticuerpos anti-T. gondii. La seroprevalencia de Leptospira spp fue de 82.3%, detectándose anticuerpos contra los serovares Grippotyphosa (58.2%), Icterohaemorrhagiae (54.6%), Pomona (40.0%), Canicola (32.7%), Bratislava (30.9%) y Georgia (21.8%). Los canes con acceso al río mostraron mayor prevalencia de Leptospira (94.9%) en comparación a los individuos que no tienen acceso (68.8%) (p&lt;0.05). Asimismo, 37.1% de los canes evaluados resultaron seropositivos para T. gondii. El estudio da a conocer la circulación de Leptospira spp y T. gondii en canes domésticos de la comunidad campesina de Corosha

The caregivers of persons with Alzheimer's disease: the profile of hidden sacrificeI caregivers delle persone affette da Malattia di Alzheimer: il profilo di un sacrificio nascosto

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