Compositional characteristics and aromatic profile of date palm seeds from seven varieties grown in Tunisia

This paper reports a discrimination study based on the physico‐chemical characteristics, fatty acids and profile of volatile compounds of the seeds from seven date palm varieties (Phoenix dactylifera L.) grown in Tunisia. Date seeds contained 10.49–14.76% moisture; 6.28–11.2% fat (on a dry weight basis); 2.67–12.85% protein; 0.91–6.06% reducing sugar; 0.61–2.98% sucrose and 0.97–1.17% ash. Gas liquid chromatography revealed that the oil fraction of the date palm seeds contained eighteen fatty acids, with oleic acid (30.77–42.50%) and lauric acid (18.51–27.48%) as the main unsaturated and saturated ones. Volatile profile showed differences among varieties. In total, forty‐five compounds were identified, mainly alcohols, aldehydes and unsaturated hydrocarbons ones. This study provides evidence that the seeds of date may be a potential source of valuable nutrients with interesting functionality.     

Phenols,Flavonoids, and Antioxidant and Antibacterial Activity of Leaves and Stem Bark of Morus Species

Leaves and stem bark composition from Morus species (M. alba var. alba, M. alba var. rosa and M. rubra) was evaluated for its antioxidant and antimicrobial activities in order to enhance its therapeutic uses. Total phenolics and flavonoids contents were estimated in hydromethanolic and aqueous extracts. Results showed highest content in M. rubra leaves aqueous extract (1129 mg gallic acid equivalent/100 g dry weight and 816 mg gallic acid equivalent/100 g dry weight, respectively). Using 2,2-diphenyl-1-picrylhydrazyl assay, the highest antioxidant activity was obtained in aqueous stem barks extracts. M. alba var. alba has an IC₅₀ of 2.84 mg/ml and the IC₅₀ value of M. rubra was the highest (4.78 mg/ml). ABTS^.+ (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) method and reducing power assay were used to confirm the results from the 2,2-diphenyl-1-picrylhydrazyl test. All extracts expressed considerable free radical-scavenging properties. Hydromethanolic and aqueous extracts were tested against Staphylococcus aureus, Enterococcus feacalis, Staphylococcus epidermis, Escherichia coli, and Salmonella Typhimurium bacteria. Hydromethanolic stem bark extracts have the highest antimicrobial activities, and it may be a good antimicrobial agent for human gastrointestinal infections. This plant could be used as an additive to foods and also as a possible source to obtain new and effective herbal medicines to treat infections of multi-drug resistant strains of microorganisms.     

Antioxidant capacities of phenolic compounds and tocopherols from Tunisian pomegranate (Punica granatum) fruits

This article aims to determine the phenolic, tocopherol contents, and antioxidant capacities from fruits (juices, peels, and seed oils) of 6 Tunisian pomegranate ecotypes. Total anthocyanins were determined by a differential pH method. Hydrolyzable tannins were determined with potassium iodate. The tocopherol (α-tocopherol, γ-tocopherol, and δ-tocopherol) contents were, respectively, 165.77, 107.38, and 27.29 mg/100 g from dry seed. Four phenolic compounds were identified and quantified in pomegranate peel and pulp using the high-performance liquid chromatography/ultraviolet method: 2 hydroxybenzoic acids (gallic and ellagic acids) and 2 hydroxycinnamic acids (caffeic and p-coumaric acids). Juice, peel, and seed oil antioxidants were confirmed by ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) methods. The highest values were recorded in peels with 25.63 mmol trolox equivalent/100 g and 22.08 mmol TE/100 g for FRAP and ORAC assay, respectively. Results showed that the antioxidant potency of pomegranate extracts was correlated with their phenolic compound content. In particular, the highest correlation was reported in peels. High correlations were also found between peel hydroxybenzoic acids and FRAP ORAC antioxidant capacities. Identified tocopherols seem to contribute in major part to the antioxidant activity of seed oil. The results implied that bioactive compounds from the peel might be potential resources for the development of antioxidant function dietary food.     

Pomegranate (Punica granatum) juices: chemical composition, micronutrient cations, and antioxidant capacity

Abstract: Phenolics, flavonoids, anthocyanins, and tannins of pomegranate juices, obtained from 9 Tunisian ecotypes were quantified. Phenolics and flavonoids in the variety Tounsi (TN) (3299 mg gallic acid equivalents [GAE]/L and 636 mg quercetin equivalents [QE]/L of juice, respectively) were higher than in the variety Gabsi (GB) (1570 mg GAE/L and 135 mg QE/L of juice, respectively). The highest anthocyanins quantity was found in GB 2 with 156 mg cyanidin‐3‐glucoside equivalents (CGE)/L. TN 3 ecotype showed the highest tannins quantity with 2550 mg catechin equivalents (CE)/L of juice. TN 1 presented the highest radical‐scavenging activity (2, 2′‐azinobis‐3‐ethylbenzothiazoline‐6‐sulphonate [ABTS], IC₅₀ [50% inhibition concentration] = 525 mg/L), as well as the highest concentration of micronutrient cations (potassium and sodium). A high correlation (R²= 0.80) between antioxidant capacity and proanthocyanin contents was found, this suggests that proanthocyanins are the principal contributor in the antioxidant capacity of pomegranate. Our data suggest also that the high concentrations of K⁺ and Na⁺ may play a role in the adaptation of pomegranate to arid environments.     

Development of Turbulent Wakes Evolving from Asymmetric Shear Layers

ABSTRACT

This paper reports an experimental investigation on the response of a turbulent wake past an elongated flat plate to various upstream flow conditions Different tripping wires were placed on the upper side of the plate downstream the leading edge resulting in asymmetric shear layers evolving from the trailing edges. Mean flow and turbulent fields of the asymmetric wakes were compared to their symmetrical counterpart. The symmetrical wake was found to attain a self-similar state whereas asymmetric wakes continued to slowly evolve towards an expected asymptotic behavior at a rate that strongly depends on the imposed initial conditions.     

Identification and quantification of phenolic acids and flavonol glycosides in Tunisian Morus species by HPLC-DAD and HPLC–MS

The total polyphenol and flavonoids in leaves of Morus alba var. alba, Morus alba var. rosa and Morus rubra were determined and identification of their components was carried out. The total content of phenolics varied between 345.20 and 631.53 mg gallic acid equivalents (GAE)/100 g dry weight (DW) basis. The total amount of flavonoids ranged between 193.87 and 398.33 mg rutin equivalents (RE)/100 g DW. Thirteen compounds were isolated by chromatography, and their structures determined to be mainly flavonol glycosides and phenolic acids. Three novel components were identified as kaempferol-7-O-glucoside, quercetin-3-O-β-glucoside-7-O-α-rhamnoside and quercetin-3-O-rhamnoside-7-O-glucoside, for the first time from mulberry leaves. Others known compounds were also identified.     

Performance enhancement of the 3D OCDMA system by using dynamic cyclic shift and multi-diagonal codes

Photonic Network Communications - A new three-dimensional (3D) code is developed for spectral/time/spatial optical code division multiple access (OCDMA) system namely 3D dynamic cyclic...     

Relation between structure and mechanical properties (elastoplastic and fracture behavior) of hybrid organic–inorganic coating

The mechanical properties of various inorganic organic films were studied and compared in order to investigate the relation between structural modifications and the mechanical behavior. Films were prepared by a sol–gel process and spin-coated on silicon substrate. The organic–inorganic hybrid is composed of a mixture of colloidal silica and organosiloxane precursors. The functionality of the organosiloxane and the nature of its organic part have been modified to obtain a structural change. Mechanical properties were studied using nanoindentation. Analysis of the strength evolution as a function of depth of indentation shows the layer hardness and elastic modulus. Moreover, coating and interface toughness and residual stresses were determined by a time resolved study of energy dissipation during indentation. The structural changes were determined using liquid and solid ²⁹Si NMR spectroscopy. Quantity of partially and fully condensed species in the deposited sol and final solid are discussed in relation to the mechanical properties.     

Influence of the ion bombardment of O2 plasmas on low-k materials

In this study, special tests were devised in order to investigate the influence of ion bombardment on the damage induced in low-k dielectrics by oxygen plasmas. By placing a sample that suffered a lot of ion bombardment and one which suffered little ion bombardment simultaneously in the same plasma, it was possible to verify that ion bombardment in fact helped to protect the low-k film against oxygen plasma induced damage. Exhaustive analyses (ellipsometry, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, porosimetry, capacitance-voltage (C-V) measurements, water contact angle analysis) show that ion bombardment induced the formation of a denser top layer in the film, which then hampered further penetration of active oxygen species deeper into the bulk. This was further confirmed by other tests combining capacitively and inductively coupled plasmas. Therefore, it was possible to conclude that, at least for these plasmas, ion bombardment may help to reduce plasma induced damage to low-k materials.     

Molecular identification of the microbiota of French sourdough using temporal temperature gradient gel electrophoresis

The microbiota of four industrial French sourdoughs (BF, GO, VB and RF) was characterized by PCR temporal temperature gel electrophoresis (TTGE). The TTGE technique reveals differences in the 16S rDNA V6–V8 regions of these bacteria. DNA was extracted directly from sourdough samples. A specific TTGE fingerprint was determined for 30 bacterial species, including members of the genera Lactobacillus, Leuconostoc and Weissella, all known to be present in sourdough.These sourdoughs contain different species of lactic acid bacteria (LAB) depending on ecological conditions prevailing in the different sourdough fermentations. Only a few LAB species were found to be competitive and became dominant. Lactobacillus sanfranciscensis was observed as the most frequently found species. In sourdough GO, L. sanfranciscensis, Lactobacillus panis and two new species, Lactobacillus nantensis and Lactobacillus hammesii, were detected. Sourdough BF contain L. sanfranciscensis, Lactobacillus spicheri and Lactobacillus pontis. In sourdough VB, which differed in the process temperature, we identified exclusively L. sanfranciscensis and Leuconostoc mesenteroïdes subsp. mesenteroïdes. Lactobacillus frumenti, L. hammesii and Lacobacillus paralimentarius became the predominant species in sourdough RF. Compared with conventional bacteriological methods, the use of this new molecular approach to analyze the sourdough ecosystem should therefore allow a more complete and rapid assessment of its specific microbiota.