Dipyridamole stress echocardiography for risk stratification in hypertensive patients with chest pain

BACKGROUND: The noninvasive prognostic assessment of coronary artery disease (CAD) in hypertensive patients represents an unresolved task to date. In this study, we investigated the value of dipyridamole stress echocardiography in risk stratification of hypertensive patients with chest pain and unknown CAD. METHODS AND RESULTS: Dipyridamole stress echocardiography was performed in 257 hypertensives (110 men; age, 63+/-9 years) complaining of chest pain and without a history of CAD. No major complications occurred. Four tests were interrupted prematurely because of side effects, with 98. 4% feasibility of test. A positive echocardiographic response was found in 72 patients (27 during the low-dose [0.56 mg/kg]). During the follow-up (32+/-18 months), 27 cardiac events occurred: 3 deaths, 8 infarctions, and 16 cases of unstable angina. Moreover, 27 patients underwent coronary revascularization. At multivariate analysis, the positive echocardiographic result (OR, 5.5; 95% CI, 1.4 to 16.6) was the only predictor of hard cardiac events (death, infarction). Considering spontaneous cardiac events (death, infarction, and unstable angina) as end points, the positive echocardiographic result (OR, 4.2; 95% CI, 1.8 to 9.6) and family history of CAD (OR, 4.2; 95% CI, 1.5 to 6. 9) were independently associated with prognosis. The 3-year survival rates for the negative and the positive populations were, respectively, 97% and 87% (P=0.0019) considering hard cardiac events and 96% and 74% (P=0.0000) considering spontaneous cardiac events. CONCLUSIONS: Dipyridamole stress echocardiography is safe, highly feasible, and effective in risk stratification of hypertensives with chest pain and unknown CAD. At present, it represents an attractive option for prognostic assessment of this clinically defined population.     

PEM fuel cell testing by electrochemical impedance spectroscopy

Nowadays, proton exchange membrane fuel cells (PEMFC) are candidate as middle term power sources for automotive, stationary generation and portable power applications. In order to introduce these devices into the market an improvement in their performances seems necessary, as well as the development of an effective control system able to find their optimal operating conditions. This paper deals with electrochemical impedance spectroscopy (EIS) using an effective tool, where a cost-effective measurement hardware has been developed creating a software to analyze the results. Both single fuel cells and stacks have been tested in various operating conditions. This experimental approach allows to highlight variations of model parameters and to perform a further analysis of the processes occurring in a fuel cell through electrical circuit models. A special attention is given to the experimental results, in order to address fuel cell malfunctions using the EIS approach as an effective diagnostic method.     

Application of foliar urea to grapevines: productivity and flavour components of grapes

Urea is a non-electrically charged nitrogen (N) molecule suitable for foliar application, since it easily penetrates the epicuticular waxes and the cutin layer of leaves. Several field trials have been conducted to understand how foliar application of urea to grapevines may affect yield and grape composition compared to other N fertilisers. The effectiveness of foliar application of urea to change the flavour components of grapes depends on the N status of the grapevines related to crop load and the timing of the foliar application, which could also play a key role in basal bud fertility and stored N reserves. The application of foliar urea to grapevines may affect the concentration of N, volatile compounds, and phenolic substances in grapes without influencing yield and its components in the short term. During alcoholic fermentation, grape N concentration favours the production of non-volatile and volatile compounds that affect wine attributes, aroma, bitterness, and astringency. Other N-compounds such as biogenic amines may also be formed in wines which can be toxic to the consumer. Gene expression related to grapevine N metabolism and the identification of putative chemical markers in red and white wines after foliar N application deserves further investigation. This review aimed to evaluate the factors involved in N uptake by leaves after foliar urea fertilisation, to summarise effects on grapevine yield components and grape composition and to provide also research options for future studies in this area.     

Spin-Crossover Grafted Monolayer of a Co(II) Terpyridine Derivative Functionalized with Carboxylic Acid Groups

The synthesis and characterization of a new Co(II) spin-crossover (SCO) complex based on 4′-(4-carboxyphenyl)−2,2′:6′,2″-terpyridine ligand are reported. This complex can be successfully grafted on silver surface maintaining the SCO behavior. Thus, atomic force microscopy (AFM), matrix assisted laser desorption ionization – time-of-flight mass spectrometry (MALDI-TOF MS), Raman spectroscopy, and XPS measurements, upon surface deposition, evidence the formation of a monolayer of intact molecules grafted through carboxylate groups to the Ag surface. Three different techniques: Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS), supported by first-principles calculations, confirm that the deposited molecules undergo a gradual spin transition with temperature. This phenomenon is unprecedented for a monolayer of molecules directly grafted onto a metallic surface from solution.