Identification of odour‐active compounds in muscle of brown trout (Salmo trutta) as affected by dietary lipid sources

The effect of fatty acid composition on odour‐active compounds in brown trout (Salmo trutta) muscle was evaluated. The fillets were obtained from three groups of fish fed experimental diets containing either fish oil (FO), soybean oil (SO) or linseed oil (LO). Muscle fatty acid composition was shown to be influenced by diet. Thirty‐one odorous compounds were detected by gas chromatography/olfactometry (frequency‐of‐detection method). Most of these compounds were formed by the oxidation of unsaturated fatty acids. Independently of diet, (E)‐2‐pentenal, (E)‐2‐pentenol and (E)‐2‐hexenol contribute strongly to the odour of brown trout. (E,Z)‐2,4‐Heptadienal was detected with high frequency in fish fed diets containing high levels of n‐3 PUFAs (FO and LO groups). Hexanal, (E)‐2‐hexenal and 2‐nonanol seem to contribute most to the odour of fish fed diets containing vegetable oils. Many odorous compounds were derived from the oxidation of mono‐ and di‐unsaturated fatty acids, which could be promoted by high levels of PUFAs. © 2002 Society of Chemical Industry     

Chemical Coupling of Carbon Nanotubes and Silicon Nanoparticles for Improved Negative Electrode Performance in Lithium‐Ion Batteries

Multi‐walled carbon nanotube (MWCNT)/silicon nanocomposites obtained by a grafting technique using the diazonium chemistry are used to prepare silicon negative electrodes for lithium‐ion batteries. The covalent bonding of the two compounds is obtained via mono‐ and multi‐layers of phenyl bridges, leading to an ideal dispersion of MWCNTs and silicon nanoparticles that are bound together. The presence of MWCNTs close to silicon nanoparticles enhances the electronic pathway to the active material particles and probably helps to prevent silicon decrepitation upon repeated lithium insertion/extraction by improving the mechanical stability of the electrode at a nanoscale level. This effect results in the enhancement of cycling ability and capacity, which are demonstrated by comparing the nanocomposite electrode to a simple mixture of the two compounds. This technique can be applied to other carbon conductive additives together with silicon or other nanosized active compounds.     

Wavelength‐Emission Tuning of ZnO Nanowire‐Based Light‐Emitting Diodes by Cu Doping: Experimental and Computational Insights

The band‐gap engineering of doped ZnO nanowires is of the utmost importance for tunable light‐emitting‐diode (LED) applications. A combined experimental and density‐functional theory (DFT) study of ZnO doping by copper (Zn²⁺ substitution by Cu²⁺) is presented. ZnO:Cu nanowires are epitaxially grown on magnesium‐doped p‐GaN by electrochemical deposition. The heterojunction is integrated into a LED structure. Efficient charge injection and radiative recombination in the Cu‐doped ZnO nanowires are demonstrated. In the devices, the nanowires act as the light emitters. At room temperature, Cu‐doped ZnO LEDs exhibit low‐threshold emission voltage and electroluminescence emission shifted from the ultraviolet to violet–blue spectral region compared to pure ZnO LEDs. The emission wavelength can be tuned by changing the copper content in the ZnO nanoemitters. The shift is explained by DFT calculations with the appearance of copper d states in the ZnO band‐gap and subsequent gap reduction upon doping. The presented data demonstrate the possibility to tune the band‐gap of ZnO nanowire emitters by copper doping for nano‐LEDs.     

New insights into physiology and metabolism of Propionibacterium freudenreichii

Dairy propionibacteria are Actinobacteria, mainly isolated from dairy environments. Propionibacterium freudenreichii has been used for a long time as a ripening culture in Swiss-type cheese manufacture, and is more and more considered for its potent probiotic effects. This review summarises the knowledge on the main P. freudenreichii pathways and the main features explaining its hardiness, and focuses on recent advances concerning its applications as a cheese ripening agent and as a probiotic for human health. Propionibacteria have a peculiar metabolism, characterised by the formation of propionic acid as main fermentation end-product. They have few nutritional requirements and are able to use a variety of carbon substrates. From the sequence of P. freudenreichii CIRM-BIA1^T genome, many pathways were reconstituted, including the Wood-Werkman cycle, enzymes of the respiratory chain, synthesis pathways for all amino acids and many vitamins including vitamin B₁₂. P. freudenreichii displays features allowing its long-term survival. It accumulates inorganic polyphosphate (polyP) as energy reserve, carbon storage compounds (glycogen), and compatible solutes such as trehalose. In cheese, P. freudenreichii plays an essential role in the production of a variety of flavour compounds, including not only propionic acid, but also free fatty acids released via lipolysis of milk glycerides and methyl-butanoic acids resulting from amino acid degradation. P. freudenreichii can exert health-promoting activities, such as a bifidogenic effect in the human gut and promising immunomodulatory effects. Many P. freudenreichii properties involved in adaptation, cheese ripening, bio-preservation and probiotic effects are highly strain-dependent. The elucidation of the molecular mechanisms involved is now facilitated by the availability of genome sequence and molecular tools. It will help in the selection of the most appropriate strain for each application.     

Fruit juice-induced endothelium-dependent relaxations in isolated porcine coronary arteries: evaluation of different fruit juices and purees and optimization of a red fruit juice blend

Numerous studies have indicated that several polyphenol-rich sources such as red wine and green tea are potent inducers of endothelium-dependent relaxations in isolated arteries. As various fruits and berries are known to contain high levels of polyphenols, the aim of the present study was to assess the ability of selected pure fruit juices and purees as well as blends to cause endothelium-dependent relaxations in isolated arteries. Vascular reactivity was assessed using porcine coronary artery rings, and fruit juices, purees and blends were characterized for their content in vitamin C, total phenolic, sugar and antioxidant activity. Fruit juices and purees caused variable concentration-dependent relaxations, with blackcurrant, aronia, cranberry, blueberry, lingonberry, and grape being the most effective fruits. Several blends of red fruits caused endothelium-dependent relaxations. Relaxations to blend D involved both a NO- and an EDHF-mediated components. The present findings indicate that some berries and blends of red fruit juices are potent inducers of endothelium-dependent relaxations in the porcine coronary artery. This effect involves both endothelium-derived NO and EDHF, and appears to be dependent on their polyphenolic composition rather than on the polyphenolic content.     

Failure analysis defect location on a real case 55 nm memory using dynamic power supply emulation

Static and dynamic techniques for defect location are well established in the failure analysis flow of a failing integrated circuit. When a circuit shows an overconsumption on power supply, the useful static techniques are laser stimulation (OBIRCH, TIVA, LIVA, etc.) or photoemission. When the electrical signature is a soft fail, a functional fault or a timing issue the analyst will use dynamic techniques like dynamic laser mapping (SDL, xVM, LVI, etc.), dynamic photoemission or internal probing (Ebeam, TRE, LVP, etc.) by applying a looping test sequence which emulates the fail.In this paper we will present a real case analysis on a circuit showing a static signature (over consumption) and also a functional fault. Both static and dynamic location techniques have been used for the defect location, plus a non conventional approach by applying a clocked power supply sequence to the circuit. A comparison is done between the different signatures and we show that dynamic power supply emulation can bring some additional information on the defect location which is not detected with the conventional static/dynamic approach.     

Parametric study for dewetted Bridgman method: crystal–crucible gap dependence on the Bond and Laplace numbers and on contact angle

In order to analyze the dependence of the crystal-crucible gap on the Bo and La numbers, a parametric study has been performed for two different cases: the sum of the contact angle (θ _c) and the growth angle (α _e) is smaller or larger then 180°. The limit regimes of the main parameters ( La ? - ￥,  La ? + ￥,  Bo ? + ￥,  Bo ? 0 ) \left( {La \to - \infty ,\;La \to + \infty ,\;Bo \to + \infty ,\;Bo \to 0} \right) of the problem were first studied. Then the non-dimensional Laplace equation has been solved numerically in the axi-symmetric case for various values of the parameters and the results are presented as graphical plots. It is shown that the main variations of the gap thickness are localized in the intermediary regimes. Another interesting point is that the gap thickness ([(e)\tilde] ) (\tilde{e} ) shows a maximum when the Bo and La numbers are varied. For growing crystals with a uniform radius, since, by definition, the sensitivity to small variations in the relevant parameter is minimal at the maximum, it is advisable to work at the parameter values which yield a maximum gap size.     

Co-fired AlN–TiN assembly as a new substrate technology for high-temperature power electronics packaging

New wide-band gap semiconductors (SC) for power electronics such as SiC, GaN and diamond will allow higher power densities, leading to higher operating temperatures. However, the surrounding materials will also undergo an increase in temperature, meaning that a parallel effort is needed in SC packaging technologies research. One of the essential components, the substrate, is used to insulate electrically the SC from the rest of the system, drain the generated heat and provide a path to connect the SC to the rest of the system. Direct bonded copper (DBC) and active metal-brazed (AMB) substrates have limited temperature and cycling operation, owing to the large differences in the thermal expansion coefficients between the ceramics and the metals. In this work we propose a new and original substrate technology based on two co-sintered ceramics: an insulating ceramic (AlN) and a conductive one (TIN). The microstructure, the chemical compatibility and the electrical properties indicate that the proposed substrate could operate at a temperature above 200 °C the current substrate technologies, which makes it particularly attractive for high-temperature power electronics applications.     

Adaptation of Bacillus cereus,an ubiquitous worldwide-distributed foodborne pathogen,to a changing environment

Consequences of climate change on the ecology of pathogens are difficult to forecast. However changes affecting microorganisms will likely involve already known evolution or adaptation mechanisms. Bacillus cereus is a frequent cause of foodborne poisonings and is known as a soil borne bacterium. B. cereus may represent an interesting model to study the impact of climate change on foodborne pathogens. The B. cereus group (or B. cereus sensu lato) displays a wide diversity of strains recently distributed in seven major phylogenetic groups. B. cereus growth domains range from psychrotrophic to nearly thermophilic. Current climate selects B. cereus distribution: psychrotrophes are more common in cold areas, while mesophiles prevail in tropical soils. In response to external signals, B. cereus may adapt to changing environments by varied mechanisms. Some illustrations of the signal transduction systems (two-component systems, alternative σ factors) and of the mechanisms of B. cereus adaptation to major environmental factors (temperature, carbon source, redox potential and pH) are proposed. The environment of sporulation has an impact on spore properties; heat resistance is positively correlated with sporulation temperature. Surveillance needed to detect changes in the epidemiology of B. cereus foodborne poisonings as a consequence of climate change is discussed.     

Elaboration of Monophasic and Biphasic Calcium Phosphate Coatings on Ti6Al4V Substrate by Pulsed Electrodeposition Current

Calcium phosphate coatings on Ti6Al4V substrates are elaborated by pulsed electrodeposition. The surface morphology and chemical composition of the coatings are characterized by SEM–EDS. The obtained results are systematically confirmed at the nanometre scale using TEM. Moreover, XRD is performed in order to identify the coatings phases. The results show that pulsed electrodeposition allows uniform coatings to be obtained without the holes and craters usually observed with classical electrodeposition. After appropriate heat treatment, these coatings have a biphasic composition of stoichiometric hydroxyapatite and β‐tricalcium phosphate. Moreover, the addition of 9% H₂O₂ to the electrolyte leads to monophasic coatings made of stoichiometric hydroxyapatite. As an indication of the passive nature of the electrodeposited coating, electrochemical potentiodynamic tests are performed in physiological solution in order to determine the corrosion behaviour of these coatings.