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1.
a four-step synthesis of monoalkylated benzidin is reported for immunogen preparation against benzidin dye. Use of 10% H2SO4/ dioxan for N-Boc cleavage avoids the cyclisation of 4-benzidinyl butyric acid into the corresponding lactam observed with the classical TFA/ CH2Cl2 system. 相似文献
2.
Antonio Gaudiello Rejeb Hadiji 《Calculus of Variations and Partial Differential Equations》2010,39(3-4):593-619
In this paper, starting from the classical 3D micromagnetic energy, we determine, via an asymptotic analysis, the free energy of two joined ferromagnetic thin films. We distinguish different regimes depending on the limit of the ratio between the small thicknesses of the two films. 相似文献
3.
S. Ben Rejeb A. Bhouri M. Debbichi J.-L. Lazzari M. Said 《Superlattices and Microstructures》2011,50(4):277-288
Reliable and precise knowledge about the strain and composition effects on the band structure properties is crucial for the optimization of InGaN based heterostructures for electronic and optoelectronic device applications. AlInGaN as quaternary barrier material permits to control the band gap and the lattice constant independently. Using the model solid theory and the multi-band k.p interaction model, we investigate the composition effects on band offsets and band structure for pseudomorphic Ga1−xInxN/AlzInyGa1−y−zN (0 0 1) heterointerfaces having zinc-blende structure. The results show that both conduction and valence band states are strongly modified while varying In and Al contents in the well and barrier materials. Furthermore, it is found that using AlInGaN as the barrier material allows the design of heterostructures including InGaN wells with tensile, zero or compressive strain. Such results give new insights for III-nitride compounds based applications and especially may guide the design of white-light emission diodes. 相似文献
4.
In this paper, starting from the classical 3D non-convex and nonlocal micromagnetic energy for ferromagnetic materials, we determine, via an asymptotic analysis, the free energy of a multi-structure consisting of a nano-wire in junction with a thin film and of a multi-structure consisting of two joined nano-wires. We assume that the volumes of the two parts composing each multi-structure vanish with the same rate. In the first case, we obtain a 1D limit problem on the nano-wire and a 2D limit problem on the thin film, and the two limit problems are uncoupled. In the second case, we obtain two 1D limit problems coupled by a junction condition on the magnetization. In both cases, the limit problem remains non-convex, but now it becomes completely local. 相似文献
5.
V. Pichon H. Rogniaux N. Fischer-Durand S. Ben Rejeb F. Le Goffic M. -C. Hennion 《Chromatographia》1997,45(1):289-295
Summary The trace-level determination of organic pollutants in complex matrices is difficult and often not reliable because theccurrent
extraction procedures are non-selective. New extraction sorbents involving antigen-antibody interactions, called immunosorbents
(ISs), have been synthesised in order to trap a group of structurally related pollutants. The IS capacity is always high for
the analyte-antigen used to make the antibodies, but can be low for some related compounds. In this work, we show the relationship
that exists between capacity, break-through volume and recovery of analytes because of the competition between the structurally
related compounds for antibody sites. Breakthrough due to the overloading of the column should be avoided because calibration
curves are no longer linear. The capacity of two ISs, one made for trapping the triazine pesticide group and the second for
the phenylurea, group, have been optimised by selecting silica with 50 nm pore size. Calibration curves are linear for all
the compounds in a mixture of ten phenylureas up to a concentration of 5 to 10 μg L−1 for each compound when handling 50 mL water samples through a precolumn packed with 0.22 g of IS. Under these conditions,
reliable quantitative results are obtained because calibration curves are similar when compounds are alone or in a mixture.
Application to the clean-up of soil extracts illustrates the high selectivity and the high potential of these new sorbents
in environmental analysis.
Presented at the 21st ISC held in Stuttgart, Germany, 15th–20th September, 1996 相似文献
6.
Ines Ben Rejeb Lotfi Monser Mohamed Gargouri 《Applied biochemistry and biotechnology》2010,162(6):1536-1546
A new, simple, and original method is described for specific measurement of polyunsaturated fatty acid content in olive oil. This analytical system uses coupled enzymes, lipase and lipoxygenase. The system consists of lipase-catalyzed hydrolysis of triacylglycerol and subsequent lipoxygenation of liberated polyunsaturated fatty acids. The hydroperoxy-fatty acids formed were easily monitored by spectrophotometry at 234 nm. After being optimized, the method was validated in terms of linearity, precision sensitivity, and recovery. Linear calibration graph was obtained in the range 50–500 µg mL?1, with a correlation coefficient higher than 0.921 and a detection limit (S/N?=?3) of 15 µg mL?1. The precision of the method (relative standard deviation) for within and between days is better than 7% and 12%, respectively. The proposed method was successfully applied to the estimation of polyunsaturated fatty acids level in olive oil samples and results obtained were in excellent agreement with those obtained by the classical official method. The proposed method is accurate, simple, cheap, and can be satisfactorily used for routine analysis of edible oils. 相似文献
7.
We study the non-linear minimization problem on with , and : where presents a global minimum α at with . In order to describe the concentration of around , one needs to calibrate the behavior of with respect to s. The model case is In a previous paper dedicated to the same problem with , we showed that minimizers exist only in the range , which corresponds to a dominant non-linear term. On the contrary, the linear influence for prevented their existence. The goal of this present paper is to show that for , and , minimizers do exist. 相似文献
8.
Anti-fumonisin B1 polyclonal antibodies were isolated from the serum of rabbits, immobilized onto the surface of glutaraldehyde-activated silica or Sepharose CL-4B particles, and placed into empty small plastic solid-phase extraction cartridges. The immobilized antibodies were evaluated for their ability to retain fumonisin B1 and fumonisin B2. Cartridge capacity and elution conditions were determined, and the results were compared to those obtained with a commercially available cartridge. The cartridges, which were tested for their effectiveness to isolate the fumonisins from extracts of corn flour and nacho chips, detected fumonisins down to levels of about 20 ng/g. However, additional cleanup was required for detection at lower concentrations. With the use of a strong anion-exchange cartridge as a preliminary cleanup before immunoaffinity chromatography, the detection limit reached 2-5 ng/g in the products tested. The silica sorbent material exhibited strong interactions with the fumonisins, requiring acidified ethanol-water mixtures for elution and resulting in an additional degree of selectivity in isolating fumonisins from sample extracts. The silica-based immunoaffinity cartridges were successfully reused more than 10 times; the Sepharose-based cartridges were less robust. Liquid chromatography with fluorescence detection was used after prechromatographic derivatization with o-phthaldialdehyde-mercaptoethanol. 相似文献
9.
In this paper we study recurrent and almost periodic homeomorphisms on the Euclidean space Rm; we give conditions under which recurrent implies periodic. On the other hand we give properties of elements of compact groups of diffeomorphisms on manifolds. 相似文献
10.
Anne Vessires Nathalie Fischer‐Durand Franck Le Bideau Pierre Janvier Jan‐Martin Heldt Samy Ben Rejeb Grard Jaouen 《应用有机金属化学》2002,16(11):669-674
We report a new, non‐isotopic, immunoassay (CMIA) for chlortoluron, a pesticide of the phenylurea family. The novel feature of this assay is the use of metal carbonyl complexes as tracers and Fourier‐transform infrared (FT‐IR) spectroscopy as the detection method. We describe the synthesis of three tracers, derivatives of chlortoluron with an attached cyclopentadienyl manganese tricarbonyl moiety. Quantitative analysis of these tracers, by FT‐IR spectroscopy was performed by simple measurement of the absorbance peak at 2033 cm?1, characteristic of the νCO of the metal‐carbonyl unit. Immunoassays were carried out using the IgG fraction of rabbit antiserum. Standard curves obtained by CMIA for the three tracers showed the feasibility of this technique for chlortoluron assay. However, the IC50 and IC90 values obtained with the three tracers varied widely, with the long‐chain tracer 12 giving the most sensitive assay for chlortoluron, with an IC50 value of 50 pmol (21 µg l?1) and an IC90 of 6.5 pmol (2.7 µg l?1). Copyright © 2002 John Wiley & Sons, Ltd. 相似文献