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121.
Lemay SG van den Broek DM Storm AJ Krapf D Smeets RM Heering HA Dekker C 《Analytical chemistry》2005,77(6):1911-1915
We report a new technique for fabricating electrodes for electrochemical applications with lateral dimensions in the range 15-200 nm and a reproducible, well-defined geometry. This technique allows determining the electrode size by electron microscopy prior to electrochemical measurements and without contamination of the metal electrode. We measured the diffusion-limited current with stepped-current voltammetry and showed that its dependence on electrode size can be quantitatively understood if the known geometry of the electrodes is explicitly taken into account. 相似文献
122.
Sthal F Galliou S Gufflet N Mourey M 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2005,52(1):27-30
In order to predict the phase noise in crystal oscillators an enhanced phase-noise model has been built. With this model, the power spectral densities of phase fluctuations can be computed in different points of the oscillator loop. They are calculated from their correlation functions. The resonator-caused noise as well as the amplifier-caused noise are taken into account and distinguished. To validate this enhanced model, the behavior of a batch of 10 MHz quartz crystal oscillators is observed and analyzed. The tested batch has been chosen in a facility production. Their associated resonators have been selected according to the value of their resonant frequency and their motional resistance. Open-loop and closed-loop measurements are given. The phase noise of the overall oscillator working in closed loop is provided by the usual active method. Theoretical and experimental results are compared and discussed. 相似文献
123.
We described herein, the construction of an organic phase enzyme electrode (OPEE) via polyphenol oxidase (PPO) entrapment within a hydrophilic polypyrrole film electrogenerated from on a new bispyrrolic derivative (1) containing a long hydrophilic spacer. The so-called “adsorption step procedure” was adopted for the preparation of the organic phase PPO biosensor. The amperometric detection of catechol was carried out in anhydrous chloroform at −0.2 V versus Ag/AgCl. The electroanalytical parameters of the biosensor strongly depend on its configuration and on the hydration state of the enzyme matrix. The best sensitivity obtained for catechol in chloroform was 15.6 mA M−1 cm−2. 相似文献
124.
Wichard T Poulet SA Halsband-Lenk C Albaina A Harris R Liu D Pohnert G 《Journal of chemical ecology》2005,31(4):949-958
In recent years a negative influence of diatom-derived ,,,-unsaturated aldehydes (PUA) on the reproductive success of copepods and invertebrates has been suggested. Since adverse chemical properties of diatoms would question the traditional view of the marine food web, this defense mechanism has been investigated in detail, but the PUA-release by test organisms has only been determined in a few cases. The observed effects were nevertheless frequently discussed from a general point of view often leading to contradictory conclusions. We have examined the PUA-production of 50 diatom species (71 isolates) in order to provide a basis for the interpretation of laboratory and field results on the influence of diatom food on the reproductive success of their consumers. PUA-production is species and strain dependent. Thirty-six percent of the investigated species (38% of the cultivated isolates) release ,,,-unsaturated aldehydes upon cell disruption in concentrations from 0.01 to 9.8 fmol per cell. Thalassiosira rotula and Thalassiosira pacifica, major spring-bloom forming diatoms isolated from Roscoff (Bretagne, English Channel, France) and Puget Sound (Washington, USA) were among the PUA-producing strains. 相似文献
125.
Cristiano Garino Laurian Zuidmeer Justin Marsh Alison Lovegrove Maria Morati Serge Versteeg Piet Schilte Peter Shewry Marco Arlorio Ronald van Ree 《Molecular nutrition & food research》2010,54(9):1257-1265
Scope: 2S albumins are the major allergens involved in severe food allergy to nuts, seeds, and legumes. We aimed to isolate, clone, and express 2S albumin from hazelnut and determine its allergenicity. Methods: 2S albumin from hazelnut extract was purified using size exclusion chromatography and RP‐HPLC. After N‐terminal sequencing, degenerated and poly‐d(T) primers were used to clone the 2S albumin sequence from hazelnut cDNA. After expression in Escherichia coli and affinity purification, IgE reactivity was evaluated by Immunoblot/ImmunoCAP (inhibition) analyses using sera of nut‐allergic patients. Results: N‐terminal sequencing of a ~10 kDa peak from size exclusion chromatography/RP‐HPLC gave two sequences highly homologous to pecan 2S albumin, an 11 amino acid (aa) N‐terminal and a 10aa internal peptide. The obtained clone (441 bp) encoded a 147aa hazelnut 2S albumin consisting of a putative signal peptide (22 aa), a linker peptide (20 aa), and the mature protein sequence (105 aa). The latter was successfully expressed in E. coli. Both recombinant and natural 2S albumin demonstrated similar IgE reactivity in Immunoblot/ImmunoCAP (inhibition) analyses. Conclusion: We confirmed the postulated role of hazelnut 2S albumin as an allergen. The availability of recombinant molecules will allow establishing the importance of hazelnut 2S albumin for hazelnut allergy. 相似文献
126.
Serge Laplante Nathalie Souchet Piotr Bryl 《European Journal of Lipid Science and Technology》2009,111(2):135-141
Among the fat fish species available from Eastern Quebec (Canada), whole Atlantic mackerel (Scomber scombrus) and herring (Clupea harengus) represent abundant fishery resources which are currently under‐utilized. They have relatively high contents of oil and coenzyme Q10 (CoQ10) in their tissues, which could be valuable for nutraceutical applications. Therefore, two low‐temperature extraction processes were compared for the recovery of oil and CoQ10 from these resources, such as enzymatic hydrolysis using Protamex? and supercritical CO2 (SCO2) using fish lyophilizates. The results revealed that highest yields of oil and CoQ10 were obtained using the enzymatic hydrolysis process with mackerel. Whatever the process used, CoQ10 concentrations were higher in herring oil, due mainly to a more selective extraction of CoQ10 over that of the oil. The highest CoQ10 recovery rates (extraction efficiencies) were obtained using the enzymatic hydrolysis process with both types of fish, but also the SCO2 process with herring under some conditions. For mackerel, the lower CoQ10 recovery rates obtained from the SCO2 process were explained by its more important matrix effect. An economic assessment of both processes revealed that the enzymatic hydrolysis extraction process would be the most promising for up‐scaling the recovery of oil and CoQ10 from these resources. 相似文献
127.
Linear Precoders for Bit-Interleaved Coded Modulation on AWGN Channels: Analysis and Design Criteria
Simoens F. Wymeersch H. Moeneclaey M. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(1):87-99
This paper investigates linear precoding for bit-interleaved coded modulation (BICM) on additive white Gaussian noise (AWGN) channels. Concatenating a linear precoder as an inner encoder with an outer (convolutional) encoder produces a powerful code with a limited decoding complexity. Linear precoders are examined and optimized for two scenarios: using (i) a noniterative decoding strategy and (ii) an iterative decoding strategy under a perfect feedback assumption. The precoder design is based on an information-theoretical approach, on the one hand, and a pair-wise error probability (PEP) analysis, on the other hand. Both approaches render convenient precoder design rules. For a binary phase-shift keying (BPSK) signal set, the optimal precoders that result from these rules are also derived. Numerical results confirm the analytical findings and simulations illustrate the effectiveness of the approach. 相似文献
128.
In this paper, we study an E0-like combiner with memory as the keystream generator. First, we formulate a systematic and simple
method to compute correlations of the FSM output sequences (up to certain bits). An upper bound of the correlations is given,
which is useful to the designer. Second, we show how to build either a uni-bias-based or multi-bias-based distinguisher to
distinguish the keystream produced by the combiner from a truly random sequence, once correlations are found. The data complexity
of both distinguishers is carefully analyzed for performance comparison. We show that the multi-bias-based distinguisher outperforms
the uni-bias-based distinguisher only when the patterns of the largest biases are linearly dependent. The keystream distinguisher
is then upgraded for use in the key-recovery attack. The latter actually reduces to the well-known Maximum Likelihood Decoding
(MLD) problem given the keystream long enough. We devise an algorithm based on Fast Walsh Transform (FWT) to solve the MLD
problem for any linear code with dimension L and length n within time O(n+L⋅2
L
). Meanwhile, we summarize a design criterion for our E0-like combiner with memory to resist the proposed attacks. 相似文献
129.
Peng Zhu Serge Méjean Eric BlanchardRomain Jeantet Pierre Schuck 《Journal of food engineering》2011,105(3):460-467
A predictive tool (SD2P®) based on a drying by desorption method was recently developed in order to determine the key process parameters values prior to spray drying. However, the SD2P® software cannot currently take into account the risk of stickiness during the process. In the study reported here, new standardized desorption method was tested and with this new method an equation was proposed to evaluate the dry glass transition temperature (Tg) of a concentrate according to its total solid content, its viscosity and its average evaporation rate. The concentrate’s behaviour during spray drying could then be predicted on the basis of the Tg. Four validation experiments were performed using different infant formula samples; the concentrates prepared from the four infant formula powders were then spray dried using a one-stage pilot dryer. The drying parameters were predicted using the SD2P® software. The results showed that the Tg predicted using this method were 18-30 °C higher than Tg measured by DSC (Differential Scanning Calorimetry). The drying temperatures predicted by SD2P® corresponded well to the values measured and this new method can correctly predict the behaviour of a concentrate with regard to spray drying. The advantage of the method presented here is that it can easily and quickly evaluate a concentrate’s Tg range and spray drying behaviour by direct analysis of the fresh concentrate sample. 相似文献
130.
Serge Nyallang Nyamsi Mykhaylo Lototskyy Ivan Tolj 《International Journal of Hydrogen Energy》2018,43(50):22568-22583
Thermo-chemical energy storage based on metal hydrides has gained tremendous interest in solar heat storage applications such as concentrated solar power systems (CSP) and parabolic troughs. In such systems, two metal hydride beds are connected and operating in an alternative way as energy storage or hydrogen storage. However, the selection of metal hydrides is essential for a smooth operation of these CSP systems in terms of energy storage efficiency and density. In this study, thermal energy storage systems using metal hydrides are modeled and analyzed in detail using first law of thermodynamics. For these purpose, four conventional metal hydrides are selected namely LaNi5, Mg, Mg2Ni and Mg2FeH6. The comparison of performance is made in terms of volumetric energy storage and energy storage efficiency. The effects of operating conditions (temperature, hydrogen pressure and heat transfer fluid mass flow rates) and reactor design on the aforementioned performance metrics are studied and discussed in detail. The preliminary results showed that Mg-based hydrides store energy ranging from 1.3 to 2.4 GJ m?3 while the energy storage can be as low as 30% due to their slow intrinsic kinetics. On the other hand, coupling Mg-based hydrides with LaNi5 allow us to recover heat at a useful temperature above 330 K with low energy density ca.500 MJ m?3 provided suitable operating conditions are selected. The results of this study will be helpful to screen out all potentially viable hydrides materials for heat storage applications. 相似文献