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

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)

EFFECTS OF ALLOPURINOL ON RENAL FUNCTION DECLINE IN HYPERTENSIVE PATIENTS WITH CHRONIC KIDNEY DISEASES

Aim: To evaluate retrospectively the effects of allopurinol treatment on renal function decline in non-gouty hypertensive patients with moderate-to-severe CKD. Methods: We selected 22 patients treated with allopurinol (A) (100–300 mg/die) that were compared with 44 subjects not treated with this drug (B), matched with A for estimated glomerular filtration rate (eGFR), age, gender and blood pressure values. Results: After a mean follow-up period of 16 months no significant difference was observed between the two groups regarding eGFR decline (A: -6.8 ± 11.6 ml/min/1.73 m2; B: -4.2 ± 9.3 ml/min/1.73 m2). Furthermore, the percentage of subjects with a value of eGFR reduction above the median was not significantly different in the two groups (A: 59 %; B: 41 %; p = 0.16). The absence of a significant effect of allopurinol on the eGFR decline was confirmed by the multiple logistic regression analysis, where the variables associated with a greater eGFR reduction were the proteinuria and the baseline value of GFR. Conclusions: Our findings are in disagreement with previous studies showing a nephroprotective effect of allopurinol. Further studies, with a randomized controlled design, are needed to understand whether or not pharmacological treatment of asymptomatic hyperuricemia may preserve renal function

RELATIONSHIPS OF SERUM URIC ACID WITH PLASMA RENIN ACTIVITY AND PLASMA ALDOSTERONE IN UNTREATED HYPERTENSIVE SUBJECTS

In experimental studies conducted in rats, raising serum uric acid (SUA) levels resulted in stimulation of intrarenal renin expression. Studies in humans exploring the association of SUA with plasma renin activity (PRA) yielded conflicting results. Moreover, little is known about the relationship between plasma aldosterone concentration (PAC) and SUA. The aim of our study was to analyse the relationships between SUA, PRA and PAC and the influence of age and gender on these relationships in a group of subjects with primary hypertension. We enrolled 281 patients (men 59%), with untreated primary hypertension and normal renal function. The study population wad divided in two subgroups on the basis of the median value of age (47 years). Spearman’s rank-correlation analyses showed that SUA was significantly associated with PRA and with PAC in the overall study population (rho = 0.16, p = 0.007; and rho = 0.23, p < 0.001, respectively), and in the subgroup of subjectsyounger than 47 years (rho = 0.19, p = 0.02; and rho = 0.33, p < 0.001, respectively). The separate analysis by gender disclosed a statistically significant correlation between SUA and PAC in men (rho = 0.20, p = 0.01), whereas in the same gender the correlation between SUA and PRA did not reach statistical significance (rho = 0.14, p = 0.08). No significant correlations were observed between the same variables in subjects older than 47 years and in women. All the associations between SUA, PRA and PAC lost statistical significance in logistic multiple regression analyses aimed at assessing the factors independently associated with an elevation of PRA and of PAC (third tertiles of their distribution). Our results, showing significant relationships of SUA with PRA and PAC only in univariate analyses, seem to suggest that the associations previously reported in some studies between these variables, and particularly that between SUA and PRA, may be mediated by various confounding factors, such as serum creatinine and body mass index

RELAZIONE TRA ENDOTELINA-1 PLASMATICA E STIFFNESS AORTICA IN PAZIENTI IPERTESI CON MALATTIA RENALE CRONICA

Vari studi hanno dimostrato come la stiffness arteriosa aumenti con il progressivo deterioramento della funzione renale. Una correlazione inversa è stata altresì dimostrata fra livelli plasmatici di endotelina-1 (ET-1) e filtrato glomerulare (GFR). Dati sperimentali hanno evidenziato che l’infusione di ET-1 è seguita da un incremento della stiffness arteriosa ed il trattamento con antagonisti del recettore ET-A dell’ET-1 in pazienti nefropatici ha comportato una riduzione della rigidità aortica, in parte indipendentemente dagli effetti sulla pressione arteriosa. Pochi dati esistono in letteratura sulle relazioni tra distensibilità aortica e concentrazioni plasmatiche di ET-1 in pazienti con malattia renale cronica (CKD). Lo scopo del nostro studio è stato quello di valutare la relazione tra livelli circolanti di ET-1 e velocità dell’onda sfigmica (PWV) aortica in un gruppo di pazienti ipertesi con CKD. Abbiano arruolato 107 soggetti ipertesi (età media 58 ± 13 anni, 56 % uomini, GFR medio 44 ml/min/1.73 m2), con CKD stadi 1-4 (classificati in accordo con le linee guida NKF). L’ET-1 plasmatica è stata dosata mediante metodica immunoenzimatica. La PWV aortica è stata misurata mediante metodica oscillometrica automatica computerizzata (Arteriograph). Il GFR è stato stimato mediante l’equazione dello studio MDRD a 4 variabili. I pazienti (n = 46) con valori più elevati di PWV (> 12 m/sec) hanno mostrato concentrazioni plasmatiche maggiori di ET-1 rispetto ai soggetti con PWV < 12 m/sec (4.3 ± 0.9 vs 3.9 ± 0.8 pg/ml; p = 0.01 e p = 0.02, prima e dopo correzione per età, sesso e pressione arteriosa media). Una correlazione statisticamente significativa è stata osservata tra ET-1 e PWV (r = 0.34; p < 0.001). Tale associazione è rimasta significativa anche dopo correzione per vari fattori confondenti all’ analisi di regressione multipla stepwise (beta = 0.29; p = 0.001). I nostri risultati sembrano suggerire che l’influenza sfavorevole esercitata dalla riduzione della funzione renale sulla elasticità delle grandi arterie possa, almeno in parte, essere mediata da un incremento dei livelli di ET-

[PP.07.19] ASSOCIATION OF MAXIMUM SPEED OF BLOOD PRESSURE RISE DURING 24-H ABPM WITH SUBCLINICAL RENAL DAMAGE IN ESSENTIAL HYPERTENSION

Objective: Experimental studies documented that the mechanical injury of intravascular pressure on the vessel wall, which results in vascular remodelling and atherosclerosis, may be more closely associated to oscillatory than to steady laminar shear stress This suggests that the hypertensive patient's prognosis may depend not only on average BP level but also on the degree and rate of BP variation. Little is known about the relationships between early renal abnormalities and the rate of BP changes assessed by intermittent 24-h ambulatory BP monitoring (ABPM). Our study was aimed to analyse the relationships between subclinical renal damage (SRD), defined as the presence of microalbuminuria or an estimated glomerular filtration rate (eGFR) between 30-60 ml/min/1.73 m2 and the maximum speed of BP rise (Max Slope BP) during a 24-h BP recording Design and method: The study population consisted of 389 untreated essential hypertensives (mean age: 49 +/- 13 years; males 58%), which underwent 24-h ABPM, 24-h albumin excretion rate (AER) measurement and GFR estimation, using the CKD-EPI equation. The Max Slope BP was calculated as the first derivative of the curve obtained by fitting partial Fourier series to raw BP data recorded by discontinuous 24-h ABPM. Results: The Max Slope of systolic BP (SBP) was higher in subjects with SRD (n = 117) than in those without SRD (n = 272)

Soil warming, carbon–nitrogen interactions, and forest carbon budgets

Soil warming has the potential to alter both soil and plant processes that affect carbon storage in forest ecosystems. We have quantified these effects in a large, long-term (7-y) soil-warming study in a deciduous forest in New England. Soil warming has resulted in carbon losses from the soil and stimulated carbon gains in the woody tissue of trees. The warming-enhanced decay of soil organic matter also released enough additional inorganic nitrogen into the soil solution to support the observed increases in plant carbon storage. Although soil warming has resulted in a cumulative net loss of carbon from a New England forest relative to a control area over the 7-y study, the annual net losses generally decreased over time as plant carbon storage increased. In the seventh year, warming-induced soil carbon losses were almost totally compensated for by plant carbon gains in response to warming. We attribute the plant gains primarily to warming-induced increases in nitrogen availability. This study underscores the importance of incorporating carbon–nitrogen interactions in atmosphere–ocean–land earth system models to accurately simulate land feedbacks to the climate system