Neuronal architectures with axo-dendritic polarity above silicon nanowires

An approach is developped to gain control over the polarity of neuronal networks at the cellular level by physically constraining cell development by the use of micropatterns. It is demonstrated that the position and path of individual axons, the cell extension that propagates the neuron output signal, can be chosen with a success rate higher than 85%. This allows the design of small living computational blocks above silicon nanowires.     

An Effective Power-Aware At-Speed Test Methodology for IP Qualification and Characterization

Advanced nanometer technologies have led to a drastic increase in operational frequencies resulting in the performance of circuits becoming increasingly vulnerable to timing variations. The increasing process spread in advanced nanometer nodes poses considerable challenges in predicting post-fabrication silicon performance from timing models. Thus, there is a great need to qualify basic building structures on silicon in terms of critical parameters before they could be integrated within a complex System-on-Chip (SoC). The work of this paper presents a configurable circuit and an associated power-aware at-speed test methodology for the purpose of qualifying basic standard cells and complex IP structures to detect the presence of timing faults. Our design has been embedded within test-chips used for the development of the 28 nm Fully Depleted Silicon On Insulator (FD-SOI) technology node. The relevant silicon results and analysis validate the proposed power-aware test methodology for qualification and characterization of IPs and provide deeper insights for process improvements.     

Transformations of (14C-lignin) cell walls of wheat by rumen microorganisms

The lower halves of apical internodes of wheat harvested at the flowering stage were labelled with [U-¹⁴C] phenylalanine (phe) or with [O¹⁴CH₃] sinapic acid (sin). Cell wall residues (CWR) and saponified residues (SR) were incubated in a fermenter simulating the rumen for 7 days with rumen fluid or without microorganisms (controls). PheCWR was labelled in all lignin units (measured as aldehydes from nitrobenzene oxidation), in phenolic acids and slightly in proteins. Labelling of pheSR was more lignin-specific. SinCWR and sinSR were specifically labelled in syringyl units of lignin. The fermentation of CWR resulted in phenylpropane-derived unit losses in the following decreasing order: ferulic acid>p-coumaric acid>syringaldehyde>vanillin>p-hydroxybenzaldehyde. If allowance is made for slight losses in controls, 61, 52, 61 and 63% of the phenylpropanes of pheCWR, sinCWR, pheSR and sinSR, respectively, were transformed into an acid-precipitable fraction, an acid-soluble fraction and ¹⁴CO_2. The comparison of pheCWR and sinCWR degradation showed that syringyl units were solubilised into acid-precipitable molecules to a greater extent than the other lignin units; demethylation of the syringyl units of lignins was also evident from the different productions of ¹⁴CO₂. Alkali-resistant lignins of SR were mainly transformed into acid-precipitable molecules and were weakly degraded. Lignin solubilisation and degradation seem to be governed by different mechanisms which depend on both cell wall structure and rumen microflora.     

Application of ATR-FTIR for a rapid and simultaneous determination of sugars and organic acids in apricot fruit

A simple, fast and accurate Fourier transform mid-infrared spectroscopy method was developed for simultaneously determining sugar and organic acid contents in apricot fruit slurries using the attenuated total reflectance. The potential of this method coupled with chemometric techniques based on partial least squares was assessed by comparison with currently used enzymatic determination of sucrose, glucose, fructose, malic acid and citric acid. Fruits of eight contrasted cultivars harvested at different ripening stages were used in this study and randomly divided in a calibration set (505 apricots) and in a validation set (252 apricots). The most suitable region was found in the range between 1500 and 900 cm⁻¹. Good prediction performances were obtained (R² ? 0.74 and RMSEP ? 18%). Results concerning the prediction of other quality traits such as firmness, skin colour, ethylene production, soluble solids content and titratable acidity were discussed.     

Urinary Mercapturic Acids as Markers for the Determination of Isothiocyanate Release from Glucosinolates in Rats Fed a Cauliflower Diet

Glucosinolates, found in plants of the genus Brassica, release physiologically active metabolites, such as isothiocyanates and nitriles, in the digestive tract under the action of plant or bacterial myrosinase. Isothiocyanates are excreted in the urine as their mercapturic acid derivatives. To study the influence of diet on isothiocyanate release, two groups of eight rats were offered either a cauliflower-based diet or a standard laboratory rat diet. After 10 days' adaptation to the diets release of allyl isothiocyanate (AITC) from a single oral dose of sinigrin, a glucosinolate commonly occurring in brassicas, was quantified. Each rat was dosed with 50 μmol of either sinigrin or AITC by stomach tube and urine was collected at 0, 2, 6, 24 and 48 h after administration. Three days later, rats which had previously received sinigrin were administered with AITC and vice versa. The concentrations of urinary mercapturic acids of isothiocyanates were determined by HPLC. Recoveries of the mercapturic acid derivative of AITC in each animal were used to estimate AITC production in sinigrin-dosed rats. Estimates of AITC release from sinigrin showed that a greater proportion of administered sinigrin was hydrolysed to AITC in cauliflower-fed rats than in rats fed a control diet (0·412 vs 0·134; P〈0·001). The approach should allow more rigorous investigation of the influence of dietary factors on glucosinolate hydrolysis in vivo. © 1997 SCI.     

Kinetic study of β‐carotene and lutein degradation in oils during heat treatment

The kinetics of trans‐β‐carotene and trans‐lutein degradation were individually investigated in palm olein and Vegetaline®, at four temperatures ranging from 120 to 180 °C. HPLC‐DAD analysis was carried out to monitor trans and cis carotenoid variations over the heating time at each temperature. In both oils, initial trans‐β‐carotene and trans‐lutein degradation rates increased with temperature. Trans‐lutein was found to degrade at a slower rate than trans‐β‐carotene, suggesting a higher thermal resistance. The isomers identified were 13‐cis‐ and 9‐cis‐β‐carotene, and 13‐cis‐, 9‐cis‐, 13'‐cis‐, and 9'‐cis‐lutein. In spite of the higher number of lutein cis isomers, their total amount was lower than that of β‐carotene cis isomers. Trans and cis carotenoids were involved in degradation reactions at rates that increased with temperature. All degradation rates were generally found to be lower in Vegetaline® than in palm olein. These results were explained by the initial composition of the two oils and especially their peroxide and vitamin E contents.     

Synthesis and characterization of fluorinated polyacrylate–cellulose acetate butyrate interpenetrating polymer networks

Fluorinated polyacrylates are highly hydrophobic and oleophobic. However, their poor mechanical properties prevent their development in many applications. Combination of a fluorinated polyacrylate network with a rigid cellulose acetate butyrate (CAB) network in an interpenetrating polymer network (IPN) architecture is an effective method for improving the mechanical properties of fluorinated polyacrylates. IPNs combining poly(3,3,4,4,5,5,6,6,7,7,8,8,8‐tridecafluorooctyl acrylate) (polyAcRf6) with CAB were prepared according to an in situ polymerization/crosslinking synthesis. CAB was crosslinked by addition between unmodified hydroxyl groups and the isocyanate of a pluri‐isocyanate crosslinker. The fluorinated network was obtained through free‐radical copolymerization of 3,3,4,4,5,5,6,6,7,7,8,8,8‐tridecafluorooctyl acrylate with poly(ethylene glycol dimethacrylate). The rates of formation of both networks were followed using Fourier transform infrared spectroscopy. Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) of IPNs show a single glass transition temperature and a single mechanical relaxation temperature, which are characteristic of a high degree of interpenetration between the partner networks. The mechanical properties of IPNs are greatly improved compared with those of the single fluorinated network. CAB/polyAcRf6 IPNs were prepared, and characterized using DSC and DMTA as well as contact angle measurements for their surface properties. As hoped, the mechanical properties of such materials are much improved compared with those of the fluorinated partner alone. Copyright © 2010 Society of Chemical Industry     

Gas-liquid mass transfer in taylor flow through a capillary

The gas-liquid mass transfer in two-phase flow through a capillary has been measured for water-air, ethanol-air and ethylene glycol-air systems. A semi-theoretical model has been developed and compared with experimental results. and a full computer simulations of the flow pattern and mass transfer using a flow simulation program have been made. The measured values are about 30% less than the calculated values.     

Iron oxide magnetic nanoparticles used as probing agents to study the nanostructure of mixed self-assembled monolayers

Self-assembled monolayers (SAMs) of organic molecules are of exceptional technological importance since they represent a convenient, flexible, and simple system for tuning the chemical and physical properties of surfaces. The fine control of surface properties is directly dependent on the structure of mixed SAMs which is difficult to characterize at the nanoscale with usual techniques such as scanning probe microscopies. In this study, we report on a general method to investigate at the nanoscale the structure of molecular patterns which consist in SAMs of two components. Iron oxide nanoparticles (NPs) have been used as probing agents to study indirectly the structure of mixed SAMs. Mixed SAMs were prepared by the replacement of mercaptododecane (MDD) adsorbed by mercaptoundecanoic acid (MUA) molecules on gold substrates. Therefore, the SAM surface displays both chelating carboxylic terminal groups and non-chelating methylene terminal groups. As NPs have been previously demonstrated to specifically interact with carboxylic acid groups, the increasing density in NPs was correlated with the evolution of the COOH/CH(3) terminal groups ratio. Therefore the structure of mixed SAMs was studied indirectly as well as the kinetic of the replacement reaction and its mechanism. With this aim, we took advantage of the SPR properties of the gold substrate and of the high refractive index of iron oxide nanoparticles to follow their assembling on mixed SAMs as a time resolved study. The high sensitivity and tuning of the SPR signal over a wide range of wavelengths are correlated with the NP density. Furthermore, SEM combined with image analysis has allowed studying the replacement rate of MDD by MUA in SAMs. We took also advantages of the magnetic properties of NPs to evaluate qualitatively the replacement of thiol molecules.