Composition and physicochemical properties of Combretum collinum,Combretum micranthum,Combretum nigricans,and Combretum niorense seeds and seed oils from Burkina Faso

Combretum collinum, Combretum micranthum, Combretum nigricans, and Combretum niorense are abundant unconventional seed oils of the African savannah. In this study, the proximate, mineral, amino acid, fatty acid, and triacylglycerol compositions of the four seed oils were quantified, and the oxidative and physicochemical properties were investigated. The amino acid, fatty acid, and triacylglycerol compositions were determined by using high performance liquid chromatography (HPLC) and gas chromatography respectively. Carbohydrates (57.35%–64.20%) followed by crude oils (20.07%–22.60%), proteins (11.95%–15.86%), and ashes (3.78%–6.19%) were the main constituents of the four seed species. The highest ash, crude fat, and protein contents were found in C. collinum, C. nigricans, and C. niorense, respectively. All four seed species were rich in Ca, K and Mg, and poor in methionine, cysteine, and lysine. The four seed oils had high saponification values (198.46–202.71 mgKOH/g), low acidity (1.12–2.26 mg of KOH/g of oil), and peroxide values (1.19–1.98 mEqO₂/kg of oil). The seed oils of C. micranthum and C. collinum exhibited the highest thermal oxidative stability (8.10 and 9.79 h at 160°C). Oleic (40.49%–56.69%), palmitic (15.17%–24.27%) and linoleic (9.49%–14.50%) acids were the predominant fatty acids of the four seed oils. The results showed that the four seed species and seed oils had good chemical composition and physicochemical properties making them suitable for food and non-food application.     

Re-examination of the structural properties of solid solutions SrxCa1−xCO3

We have re-examined the evolution of orthorhombic cell parameters as a function of the substitution parameter x in solid solutions Sr_xCa_1−xCO₃ in order to clarify contradictory results found in the literature. Calcium carbonate has been synthesized in the presence of Sr²⁺ ions (Sr/Ca molar ratio ranging from 10⁻² to 1), using experimental conditions that previously allowed us to obtain monophasic aragonite. The precipitates obtained have been analysed using powder X-ray diffractometry (XRD) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The powder XRD data confirm the occurrence of purely monophasic strontian-aragonites. Moreover, the cell parameters as well as the substitution parameter x have been refined for 0 < x < 0.5 against powder XRD data through Rietveld refinement. On the other hand, x was deduced from chemical analysis by ICP-AES. The agreement between both techniques is very satisfactory. The evolution of the cell parameters as a function of x is found to be linear within the studied range, this feature being confirmed for the overall domain (0 ≤ x ≤ 1) if one takes into account the cell parameters of aragonite CaCO₃ and strontionite SrCO₃. This result, that is consistent with the existence of continuous solid solutions obeying the Vegard's law in the Sr_xCa_1−xCO₃ system, contradicts previously published assertions.     

Aflatoxins levels in dried fruits and nuts from Rabat-Salé area, Morocco

The occurrence of aflatoxins (AFs) in dried fruits and nuts available in Rabat-Salé area (Morocco) was surveyed in this study. One hundred samples of dried fruits and nuts, purchased from retail shops and local markets from January to October 2006, were analyzed for AFs content by immunoaffinity (IAC) clean-up with liquid chromatography and fluorescence detection. Results showed that the incidences of total aflatoxins (AFT) and aflatoxin B1 (AFB1) in peanut, dried raisins, dried figs, walnut, and pistachio were 5%, 20%, 30%, 30% and 45% and 5%, 20%, 5%, 30% and 45%, respectively. The highest contamination levels of AFB1 were found in one walnut sample (2500 μg/kg) and one pistachio sample (1430 μg/kg). 5%, 20% and 20% of samples of pistachio, walnut and dried raisins exceeded the maximum tolerable limit (2 μg/kg) set for AFB1 by EU regulations. While 15% of dried figs samples were above the maximum limit (4 μg/kg) set by EU regulations for AFT. The present paper is the first report on the natural occurrence of AFs in dried fruits and nuts available in Rabat-Salé area in Morocco.     

A control synthesis approach for time discrete event systems

In this paper, we introduce a control synthesis method for discrete event systems whose behavior is dependent on explicit values of time. Our goal is to control the occurrence dates of the controllable events so that the functioning of the system respects given specifications. The system to be controlled is modeled by a time Petri net. In a previous work we proposed a systematic method to build the timed automaton which models the exact behavior of a time Petri net. Furthermore, the forbidden behaviors of the system are modeled by forbidden timed automaton locations. This paper focuses on the control synthesis method, which consists in computing new firing conditions for the timed automaton transitions so that the forbidden locations are no longer reachable.     

A global survey of effects of genotype and environment on selenium concentration in lentils (Lens culinaris L.): Implications for nutritional fortification strategies

Lentils (Lens culinaris L.) are an important protein and carbohydrate food, rich in essential dietary components and trace elements. Selenium (Se) is an essential micronutrient for human health. For adults, 55 μg of daily Se intake is recommended for better health and cancer prevention. Millions of people around the world have Se-deficient diets and biofortification may be an effective solution. The total Se concentration of lentils grown in six major lentil-producing countries were analysed to determine the potential for Se biofortification in these regions. The highest Se concentrations based on location means were found in lentils from Nepal (180 μg/kg) and southern Australia (148 μg/kg) while the lowest were those from Syria (22 μg/kg), Morocco (28 μg/kg), northwestern USA (26 μg/kg), and Turkey (47 μg/kg). Significant location effects within a country were observed for Nepal and Australia. All values were lower than previous published data for Saskatchewan grown lentils (425–672 μg/kg). Lentils originating from Australia, Nepal, or Canada could be considered good sources of Se, as consumption of 50 g would provide 13–61% of the recommended dietary allowance (RDA). Our findings indicate lentil may be appropriate as a target crop for Se biofortification and investigated as a food-based solution for populations with Se deficiencies.     

Variable range hopping conduction in n-CdSe samples at very low temperature

We reanalyzed experimental data already published in Friedman J R, Zhang Y, Dai P, et al. Phys Rev B, 1996, 53(15):9528. Variable range hopping(VRH) conduction in the insulating three-dimensional n-CdSe samples has been studied over the entire temperature range from 0.03 to 1 K. In the absence of a magnetic field, the low temperature conductivity σ of the three samples(A, B and C) obeys the Mott VRH conduction with an appropriate temperature dependence in the prefactor(σ=σ₀ exp[-(T₀/T)^p with p≈0.25). This behavior can be explained by a VRH model where the transport occurs by hopping between localized states in the vicinity of the Fermi level, E_F, without creation of the Coulomb gap(CG). On the contrary, no Efros-Shklovskii VRH is observed, suggesting that the density is constant in the vicinity of the E_F.     

The membrane fouling simulator: a suitable tool for prediction and characterisation of membrane fouling.

A new tool--the Membrane Fouling Simulator (MFS)--is developed to measure membrane fouling (pressure drop increase) in a small and simple system, representative for spiral wound membranes applied in water treatment. With the MFS, fouling development can be monitored systematically by (i) pressure drop, (ii) in situ and non-destructive (visual) observations using the sight glass and (iii) analysis of coupons sampled from the membrane sheet in the MFS. A comparison study of the MFS with spiral wound membrane elements (test rigs and a full scale installation) showed the same fouling. The MFS provided reproducible data. The small size and low water and chemical use of the MFS facilitate to perform systematic parallel studies. With the MFS, fouling of membranes applied in water treatment can be characterised.     

Modern concept of acoustic emission (AE) coupled with electrochemical measurements for monitoring the elastomer-coated carbon steel damage in phosphoric acid medium

Elastomer coatings (rubber) are industrially used to protect phosphoric acid storage tanks against corrosion. Rubber constitutes a barrier against the penetration of H₃PO₄ to metallic surface. Coatings damage induces both acid infiltration and steel corrosion. In this concept, acoustic emission (AE) monitoring technique could be used for the detection of coatings damage as well as for steel corrosion under the coating. In the present work AE was coupled to electrochemical measurements (EM) for rubber damage evaluation and steel corrosion on three types of steels (XC48, E20 and A60) at room temperature in concentrated phosphoric acid (30% P₂O₅) contaminated by Cl⁻, F⁻, SO₄²⁻. Electrochemical behaviour of steels was studied and characterized by potentiodynamic curves and polarization resistance measurement. A good correlation between acoustic emission and polarization resistance or corrosion potential measurements was found during stages of coatings damage and steels corrosion. The majority of AE activity recorded during experiments is related to hydrogen bubbles release. The release of hydrogen bubbles gives rise to two populations of signals: one impulsive and another one resonant.     

Distance determination in heterogeneous DNA model systems by pulsed EPR

Many biological systems, especially those based on nucleic acids, are structurally heterogeneous in solution. We demonstrate here the ability to measure multiple distances, of between 2 and 7 nm, from a heterogeneous mixture of double-spin-labeled DNA duplexes. We have constructed a DNA distance ruler based on the attachment of nitroxide spin labels to 2'-amino-modified nucleosides. The distribution of distances between the spin labels was obtained by Tikhonov regularization analysis of the dipolar coupling evolution data measured by using the electron paramagnetic resonance method, pulsed-electron double resonance (PELDOR). Optimization of the conditions and techniques used in the preparation of the samples has allowed us to increase the sensitivity and reduce aggregation artifacts. As a result, we have been able to demonstrate deconvolution of distances from structurally heterogeneous samples and show the limits of the technique by examining data derived from up to five DNA duplexes, in a single mixture, in which the concentration of each species was as low as 5 microM.