Changes in Fatty Acids,Tocochromanols, Carotenoids and Chlorophylls Content During Flaxseed Development

A comparative study was performed to determine tocopherols, tocotrienols, fatty acids, and pigments content during the development of three varieties of flaxseed (H52, O116 and P129). Seed samples were collected at regular intervals from 7 to 56 days after flowering (DAF). The highest content of chlorophyll (89.72–130.5 mg/kg oil) was detected at 7 DAF. The maximum level of carotenoids (52.10–65.55 mg/kg oil) was reached at 21 DAF. During seed development, unsaturated fatty acids are the major component, reaching 85% of the total fatty acids while saturated fatty acids content were about 15%. The maximum level of γ-tocopherol (585 mg/kg oil) was reached at 42 DAF in P129 variety. These results may be useful for evaluating the flaxseed quality and determining its optimal harvest period.     

Biofilm formation,virulence gene and multi-drug resistance in Salmonella Kentucky isolated in Tunisia

Food-borne diseases caused by Salmonella enterica are a significant public health concern around the world. Since 2002, S. enterica serovar Kentucky has shown an increase in several countries with the concurrent emergence of multidrug-resistant isolates. The spread of such strains in the environment poses a major public health problem. A total of 57 Salmonella Kentucky strains isolated from different sources during the period 2005 to 2008 in Tunisia, were characterized by their antimicrobial and mercury resistance profiles; ability to form a biofilm; virulence invA/spvC genes and quorum sensing sdiA gene. A total of 10.6% of the isolates demonstrated multidrug-resistance against 3 to 13 antibiotics with ciprofloxacin resistance occurring in 33% of human isolates. In addition, 37% of the isolates exhibited minimum inhibitory concentrations value to mercuric chloride, ranging from 8 to 32 μg ml^?1 and were considered as resistant strains. The majority of strains tested were able to form a biofilm, especially for environmental and animal derived isolates. Therefore, the biofilm seems to comprise a normal and favorable capability in the life of Salmonella Kentucky in the environment. Interestingly, all the isolates possessed the sdiA gene, 87.7% of isolates possessed the invA gene, and no isolate harbored the spvC gene.The emergence of resistance to ciprofloxacin in human Salmonella Kentucky isolates, added to the presence of invA and sdiA genes, and the production of biofilm could be the decisive factors in the dissemination of S. Kentucky strains on a large scale.     

Policosanol distribution and accumulation in developing corn kernels

Policosanol is a mixture of long-chain primary aliphatic alcohols. The policosanol composition of whole corn kernel was determined in three varieties of corn (Astro, GH2547, Local). The total policosanol content of GH2547 (20.5 mg/kg of dry weight) was higher than those of Local (16.6 mg/kg) and Astro (15.2 mg/kg). The major policosanol components of whole corn kernel were dotriacontanol, triacontanol and tetracosanol. The distribution of policosanol in the germ, endosperm and pericarp of corn kernels was also determined. Corn pericarp had higher contents of policosanols (72.7–110.9 mg/kg) than the endosperm (4.0–16.2 mg/kg) and germ (19.3–37.1 mg/kg) fractions. Corn pericarp policosanol was mainly triacontanol (33.63–46.29 mg/kg), dotriacontanol (22.31–39.46 mg/kg) and octacosanol (8.13–14.0 mg/kg). In contrast, the corn germ fraction contained mostly dotriacontanol (more than 50%) and no triacontanol. The main components of corn endosperm policosanol were triacontanol and hexacosanol. The level of tetracosanol was highest in the germ fraction and lowest in the endosperm fraction. The greatest change in policosanol content (expressed as mg/100 g of oil) occurred during the early stages of corn kernel development. Although the structures of the alcohol constituents of policosanol are similar, their patterns of accumulation were different. The highest levels of octacosanol and dotriacontanol were detected at 20 days after pollination (DAP) followed by a rapid decrease between 20 and 30 DAP. Triacontanol levels decreased rapidly between 10 and 40 DAP, and then remained nearly constant.     

The Effects of Essential Oils Addition on the Quality of Wild and Farmed Sea Bream (<Emphasis Type="BoldItalic">Sparus aurata</Emphasis>) Stored in Ice

The preservative effect of laurel (Laurus nobilis) and cumin (Cuminum cyminum) essential oils (EOs) on fresh vacuum-packed (VP) wild and farmed sea bream (Sparus aurata) fillets was evaluated during ice storage by microbiological, physicochemical and electrophoretic analyses. In the present study, wild (W) and farmed (F) fillet treatment included the following lots: control vacuum-packaged samples (WV and FV), VP with added EOs (0.5% v/w) of cumin (WVC and FVC), and of laurel (WVL and FVL). Wild and cultured fish were found to differ significantly in their muscle proximate compositions irrespective of fillet treatments with particularly higher fat and carbohydrate contents in farmed sea bream (4.82 and 0.32 g/100 g, respectively, vs. 1.53 and 0.22 g/100 g in wild fish). The treatment of wild and farmed sea bream fillets with laurel or with cumin EOs induced a decrease in bacterial growth by ca. 0.5 to 1 log cfu/g and in lipid oxidation by ca. 40% of TBA value, extending the shelf life of fish fillets by approximately 5 days of ice storage. However, the addition of EOs to VP fillets resulted in a reduced liquid holding capacity (LHC) throughout ice storage suggesting an early proteolysis initiation confirmed by the myofibrillar and sarcoplasmic electrophoretic profiles. Laurel and cumin EOs as natural and efficient antibacterial and antioxidant compounds can be used in conjunction with VP to enhance ice-stored sea bream quality.     

一种基于二进小波变换的图像边缘检测方法

边缘检测是图像处理和计算机视觉领域最活跃的研究课题之一。传统边缘检测方法对噪声非常敏感,针对该问题在传统边缘检测算法分析的基础上,提出了一种基于二进小波变换的图像边缘检测方法。首先,对原图像进行二进小波分解,然后对低频子图像用直方图均衡化来进行增强,对增强后的低频子图像用二进小波变换模极大值点方法进行边缘检测得到边缘图像。实验结果表明,这种边缘检测方法明显优于对原图像直接使用传统边缘检测算子或二进小波变换模极大值点的边缘检测方法。     

Influence of grafting with acrylic acid on the dyeing properties of polyamide 6.6 fibres

Polyamide 6.6 fibres were modified for the improvement of dyeing affinity using a graft copolymerisation method. These fibres were grafted with acrylic acid as monomer. The influence of the chemical modification of polyamide 6.6 fibres on the dyeing properties was investigated using a cationic dye (Red Astrazon 5BL). It was shown that the dye uptake of the modified fibres was greater than that of the unmodified fibres. The kinetic study of the cationic dye used at various grafting percentages showed an improvement of the dye build‐up rate, such as its exhaustion. In addition, an increase in the adsorption of the dye quantity fixed on the surface layer of the fibre made up of the grafted molecules was announced. Colour fastness to washing was improved with the grafting percentage. The modelling of the adsorption isotherms using Langmuir, Freundlich and Jossen relations allows the determination of isotherm constants. The results obtained from this modelling study show the existence of several models corresponding to various percentages of grafting.     

The synthesis and optical properties of novel fluorescent iminocoumarins and bis-iminocoumarins: Investigations in the series of urea derivatives

The condensation of 3-cyano-7-diethylamino-iminocoumarin with various isocyanates and diisocyanates as C-electrophiles gave a new series of N-substituted iminocoumarins and bis-iminocoumarins. The ten compounds obtained were characterized using IR, ¹H NMR, ¹³C NMR, elemental analysis and mass spectrometry. Their optical properties, studied in dichloromethane by UV/vis absorption and fluorescence spectroscopy, were found to depend strongly upon the nature of the substituent borne by the imino group. For the sake of comparison, the optical properties of selected compounds were also analyzed in ethanol. Of the iminocoumarins studied, the alkylurea derivatives displayed the most interesting spectroscopic characteristics and may be of potential use as novel fluorescent probes in media of various polarity.     

Wear behavior of Al–Cu and Al–Cu/SiC components produced by powder metallurgy

In the present study, the dry sliding wear behavior of some powder metallurgy (P/M) Al–Mg–Cu alloys with different weight percentage of Cu (0, 1, 2, 3, 4, and 5 wt%) and corresponding metal matrix composites reinforced with 5 or 10 vol% silicon carbide particles (SiC) have been carried using pin-on-disk apparatus. The tested specimens were tested against hardened steel disk as a counter face at room conditions (∼20 °C and ∼50% relative humidity). The normal load was 40 N and sliding velocity of counter face disk was 150 rpm (0.393 m/s) and total testing time of 60 min, which corresponds to a distance of 1414 m. Generally, both hardness and wear resistance were enhanced by the addition of Cu and/or SiC to the Al-4 wt% Mg alloy. The formations of mechanically mixed layer (MML) as a result of material transfer from counter face disk to the samples and vice versa were observed in all tested specimens.     

Synthesis of a novel luminescent copolymer based on bisphenol A

A new luminescent copolymer (BPAEt₂‐BP; Scheme 1 ), with short alternating divinylbiphenyl units and O‐diethylated bisphenol A (BPAEt₂), was synthesized via the Wittig reaction. The polymer is fully soluble in common organic solvents and has a number‐average molecular weight of 4600 g mol^?1 with a polydispersity index of 1.79. The structure of the polymer was confirmed by ¹H NMR, ¹³C NMR, FTIR and Raman analysis. Thermal analysis of the polymer showed good stability up to 280 °C. Furthermore, polymer film absorbs at 360 nm and emits in the blue at 426 and 451 nm. The band‐gap calculated from the UV‐vis spectrum was about 2.80 eV. A single‐layer device of the configuration indium tin oxide (ITO)/BPAEt₂‐BP/Al has a relatively low turn‐on voltage of 3 V. Copyright © 2005 Society of Chemical Industry     

Relationship between Riser and Downcomer Gas Holdups in Semi‐batch Circulating Bubble Columns

Gas holdups were measured in a circulating bubble column (CBC) using air‐water system with various additives. The liquid volume in the gas separator affected downcomer gas holdup up to volume ratio equal to 6%. Presence of surface active agents, alcohols, solid particles had little effects on the gas holdups ?_gd — a?_gr relationships. The gas holdups relationships are theoretically related by a single parameter model ?_gd = a?_gr — a + 1, and empirically by two parameter model ?_gd = a?_gr — constant. The theoretical model yielded a values ? 0.45, while the empirical model yielded a values ? 1.16. Analogy between the two models (Contreras et al., 1998) will lead to incorrect conclusions.