Bioactive Phytochemicals from Wild Arbutus unedo L. Berries from Different Locations in Portugal: Quantification of Lipophilic Components

The lipophilic composition of wild Arbutus unedo L. berries, collected from six locations in Penacova (center of Portugal), as well as some general chemical parameters, namely total soluble solids, pH, titratable acidity, total phenolic content and antioxidant activity was studied in detail to better understand its potential as a source of bioactive compounds. The chemical composition of the lipophilic extracts, focused on the fatty acids, triterpenoids, sterols, long chain aliphatic alcohols and tocopherols, was investigated by gas chromatography–mass spectrometry (GC–MS) analysis of the dichloromethane extracts. The lipophilic extractives of the ripe A. unedo berries ranged from 0.72% to 1.66% (w/w of dry weight), and consisted mainly of triterpenoids, fatty acids and sterols. Minor amounts of long chain aliphatic alcohols and tocopherols were also identified. Forty-one compounds were identified and among these, ursolic acid, lupeol, α-amyrin, linoleic and α-linolenic acids, and β-sitosterol were highlighted as the major components. To the best of our knowledge the current research study provides the most detailed phytochemical repository for the lipophilic composition of A. unedo, and offers valuable information for future valuation and exploitation of these berries.     

Electrochemical hydrodehalogenation of polychloromethanes at silver and carbon electrodes

The reductive dehalogenation of CCl₄, CHCl₃, CH₂Cl₂ and CH₃Cl has been investigated by cyclic voltammetry and controlled-potential electrolysis at Ag, glassy carbon (GC) and graphite electrodes in dimethylformamide (DMF) + 0.1 M Et₄NClO₄ in the absence and presence of a proton donor. In particular, the study was focused in the evaluation of the intermediates and final products of the reduction process and how their distribution could be affected by tuning relevant chemical and electrochemical parameters. In general, depending on the value of the applied potential, all polychloromethanes (PCMs) can be partially or completely dechlorinated, methane being exclusively formed in the latter case. The nature of the electrode material and the proton availability of the medium affect drastically the distribution of reduction products. The results point out that at both types of electrode, reduction of PCMs takes place through two competing reaction pathways both leading to methane. One reaction route involves a sequence of reductive dehalogenation steps, with the removal of one chlorine atom at a time, whereas the other is based on hydrogenolysis of carbenes and bypasses the intermediacy of partially dechlorinated PCMs. The presence of a proton source affects substantially the hydrodehalogenation efficiency, enhancing the concentration of intermediate PCMs and the final yield of methane. The silver electrode exhibits an extraordinary electrocatalytic effect resulting in remarkable positive shifts of the reduction potentials of all PCMs with respect to GC. The Ag surface strongly affects the kinetics of the dissociative electron transfer to CH_nCl_(4−n) (n = 0–3) as well as the reactivity of the intermediate radicals, carbanions and carbenes.     

Diffusion soldering using a Gallium metallic paste as solder alloy: study of the phase formation systematics

In this work preliminary results are reported on the characterization of Pb-free joints produced by using a diffusion soldering method at a process temperature of 700 °C during 20 min. The solder alloy is a metallic paste involving Ga and Al and Ni powder, and the substrates are Cu and Ni. The dissolution and diffusion-reaction processes, which take place at the interfaces of the interconnection zone, have been investigated by means of SEM and EPMA. A solid solution and intermetallic compounds (IMCs) with high melting point form as layers almost free from defect, allowing service temperatures about 500 °C higher than the process temperature. The phase stability sequence starting from the Ni to the Cu interface is the following: α′-Ni₃Ga, γ-Cu₉Ga₄, β-Cu₃Ga and (Cu) solid solution of the Ga–Cu system. The relative reaction front displacement of the layers and the implications of the present findings for the applicability of the diffusion-soldering method are also discussed.     

A new look at the long-term performance of general solar thermal systems

This work addresses the problem of evaluating the long-term performance of solar thermal systems, which is quantified through the monthly or seasonal/annual solar fraction. It is shown that for a general solar system it may be expressed as a function of monthly utilizabilities, calculated for two different temperature (radiation) levels, which correspond to minimum and maximum operating temperatures. Both systems without storage and with storage are considered. Examples for solar cooling and solar cogeneration systems are shown.     

A Direct Solver for 2D Non-Stationary Boltzmann-Poisson Systems for Semiconductor Devices: A MESFET Simulation by WENO-Boltzmann Schemes

We present preliminary results of a high order WENO scheme applied to deterministic computations for two dimensional formulation of the transients for the Boltzmann-Poisson system describing electron transport in semiconductor devices. The collisional term models optical-phonon interactions which become dominant under strong energetic conditions corresponding to nanoscale active regions under applied bias. We treat the Boltzmann Transport equation in a spherical coordinate system for the wave-vector space. The problem is three dimensional in the wave-vector space and two dimensional in the physical space, plus the time variable driving to steady states. The new formulation avoids the singularity due to the spherical coordinate system.     

Analysis of the T cell receptor repertoire in rheumatoid arthritis

BACKGROUND AND AIMS OF THE STUDY: Valve repair, where suitable, is the preferred option in patients who require mitral surgery. A number of studies have shown excellent long-term results, but most were undertaken in tertiary referral centers with a high throughput of patients. METHODS: We present our experience in 60 patients, aged 60 +/- 14 years, undergoing repair between 1984 and 1993. Most patients (83%) were in New York Heart Association (NYHA) class II or III at the time of surgery; 27% had concomitant ischemic heart disease. Almost all (98%) had posterior leaflet repair and 18% had anterior leaflet repair. Eight surgeons each performed a mean of 7.5 operations during this period. RESULTS: The 30-day mortality rate was 3.3%. There were seven late deaths. Five patients underwent reoperation for mitral regurgitation (two early, three late). At six years, 60% of patients were alive, or free of stroke or reoperation. Late follow up was obtained in 45 of 47 surviving patients: 95% were in NYHA class I or II; one-third were on anticoagulants for atrial fibrillation; 90% had mild (or less) mitral regurgitation on echocardiography. CONCLUSIONS: These data show that most patients have a very good outcome from valve repair surgery and encourage the trend towards operating earlier in the course of the disease. Adverse outcomes occurred mainly in patients who were highly symptomatic at the time of surgery. The high proportion of patients on postoperative anticoagulants underscores the importance of operating before atrial fibrillation becomes permanent.     

Performance of several Cr and Yb analytical techniques applied to samples of different biological origin (digesta or faeces)

This paper compares the performance, in terms of Cr (liquid phase marker) and Yb (solid phase marker) recovery from spiked samples, of five mineralization procedures applied to faeces, whole duodenal digesta, particulate and liquid phases of duodenal digesta, whole ruminal digesta and ruminal fluid from cattle. Two Holstein–Friesian heifers, fitted with permanent ruminal and duodenal cannulae, and fed twice daily on barley straw and a concentrate (15:85), were used as sample donors. Cr and Yb were added to the samples at 5, 25, 125 and 625 µg g^?1 dry matter, and analyzed by atomic absorption spectrometry. There were differences in marker recovery (p = 0.0481) depending on the mineralization procedure utilized but their performance was not affected by marker type (p = 0.6143). The interaction between type of sample and digestion procedure was statistically significant (p = 0.0290) and the results showed that homogeneous samples (whole duodenal digesta, the particulate phase of duodenal digesta and faeces) allowed the more even distribution of the marker and an easier and more complete mineralization. In contrast, heterogeneous samples (whole rumen digesta and rumen fluid) resulted in either a lesser attachment of markers to the particles and/or incomplete mineralization of the samples, which resulted in a higher variability between procedures. The interaction between type of sample and marker was also significant (p = 0.0426), with Cr recovery being more affected by type of sample than Yb. Copyright © 2004 Society of Chemical Industry