Global Weak Solutions for a Parabolic System Modeling a One-Dimensional Miscible Flow in Porous Media

We consider an initial boundary value problem for a nonlinear differential system of two equations. Such a system is formed by the equations of compressible miscible flow in a one-dimensional porous medium. No assumption about the mobility ratio is involved. Under some reasonable assumptions on the data, we prove the existence of a global weak solution. Our basic approach is the semi-Galerkin method. We use the technique of renormalized solutions for parabolic equations in the derivation ofa prioriestimates.     

Synthesis of fused ring heterocycles from aromatic amines with hydroximoyl chlorides

Substituted 2-arylbenzimidazoles, 2-arylbenzoxazoles and 2-arylbenzothiazoles were obtained in good yield by the reaction of hydroximoyl chlorides with ortho-substituted aromatic amines. The benzo moiety of the benzimidazoles was shown by nmr to be symmetrical, indicating that the N-H group proton of the imidazole ring is exchanging with the water protons in the DMSO-d₆ solvent.     

Study of Langmuir and Langmuir-Blodgett films of odorant-binding protein/amphiphile for odorant biosensors

To make ultrathin films for the fabrication of artificial olfactory systems, odorant biosensors, we have investigated mixed Langmuir and Langmuir-Blodgett films of odorant-binding protein/amphiphile. Under optimized experimental conditions (phosphate buffer solution, pH 7.5, OBP-1F concentration of 4 mg L(-1), target pressure 35 mN m(-1)), the mixed monolayer at the air/water interface is very stable and has been efficiently transferred onto gold supports, which were previously functionalized by self-assembled monolayers (SAMs) with 1-octadecanethiol (ODT). Atomic force microscopy and electrochemical impedance spectroscopy were used to characterize mixed Langmuir-Blodgett (LB) films before and after contact with a specific odorant molecule, isoamyl acetate. AFM phase images show a higher contrast after contact with the odorant molecule due to the new structure of the OBP-1F/ODA LB film. Non-Faradaic electrochemical spectroscopy (EIS) is used to quantify the effect of the odorant based on the electrical properties of the OBP-1F/ODA LB film, as its resistance strongly decreases from 1.18 MOmega (before contact) to 25 kOmega (after contact).     

Reactions with hydrazidoyl halides. IV. Synthesis of thiazolo[3,2-a]benzimidazoles,imidazo[2,1-6]thiazoles and pyrazolo[4,3-b]thiazines

Hydrazidoyl halides were condensed with 2-mercaptobenzimidazole yielding 4a-c and 7a,b which were cyclized to the corresponding 2-arylhydrazonothiazolo[3,2-a]benzimidazol-3-ones 5a,b and 3-substituted 2-arylazo thiazolo[3,2-a]benzimidazoles 8a,b respectively. Imidazo[2,1-b]thiazoles were obtained by the reaction of hydrazidoyl halides with 2-mercapto-4,5-dihydroimidazole. Also, hydrazidoyl halides 6a,b were reacted with 3-amino-4-mercapto-5-phenylpyrazole to give pyrazolo[4,3-b]thiazines 15a,b . The structures of the products were assigned on the basis of their elemental analysis and spectral data.     

Adsorption of Bovine Serum Albumin onto Polystyrene Latex Particles Bearing Saccharidic Moieties

The adsorption of bovine serum albumin (BSA) onto polystyrene latexes bearing various amounts of sugar moieties has been investigated as a function of pH and ionic strength and the results were compared to those for bare polystyrene latexes having negative surface charges. The functionalized latexes were produced by seeded copolymerization of (0.3 μm) liposaccharidic monomer onto polystyrene particles obtained by soap-free emulsion polymerization of styrene using potassium persulfate as initiator. At first, the electrophoretic mobility behavior of the various latexes was examined as a function of pH: a significant decrease was observed in the case of saccharide-containing latex particles compared to the bare particles. The adsorption of BSA onto these latexes exhibited a reduced amount of adsorbed BSA for those latex particles bearing saccharide groups. This adsorbed amount depends on the yield of saccharidic monomer incorporated onto the surfaces of the latex particles.     

Polymethylmethacrylate derivatives Eudragit E100 and L100: Interactions and complexation with surfactants

Precipitation or coprecipitation of polyelectrolytes has been largely investigated. However, the precipitation of polyelectrolytes via addition of charged and non‐charged surfactants has not been systematically studied and reported. Consequently, the aim of this work is to investigate the effect of different surfactants (anionic, cationic, non‐charged and zwitterionic) on the precipitation of cationic and anionic polymethylmethacrylate polymers (Eudragit). The surfactants effect has been investigated as a function of their concentration. Special attention has been dedicated to the CMC range and to the colloidal characterization of the formed dispersions. Moreover, the effect of salt (NaCl) and pH was also addressed. It is pointed out that non‐ionic and zwitterionic surfactants do not interact with charged Eudragit E100 and L100. For oppositely charged Eudragit E100/SDS and Eudragit L100/CTAB, precipitation occurs, and the obtained dispersions have been characterized in terms of particle size distribution and zeta potential. It was established that the binding of SDS molecules to Eudragit E100 polymer chains is made through the negative charges of the surfactant heads under the CMC value whereas binding of CTAB to Eudragit L100 chains is made at a CTAB concentration 5 times above its CMC. For Eudragit E100/SDS system, a more acidic medium induces aggregation. A same result was observed for the Eudragit L100/CTAB at a more basic pH. Moreover, it was observed that increasing salt concentration (higher than 100 mM) led to aggregation as generally observed for polycations/anionic surfactant systems.     

A Convenient Synthesis of Some New 1,3,4‐Thiadiazoles,Thiazoles, Pyrazolo[1,5‐a]pyrimidines,Pyrazolo[5,1‐c]triazine,and Thieno[3,2‐d]pyrimidines Containing 5‐Bromobenzofuran Moiety

1,3,4‐Thiadiazoles, pyrazolo[1,5‐a]pyrimidines, pyrazolo[5,1‐c]triazine, and thieno[3,2‐d]pyrimidines were synthesized from 1‐(5‐bromobenzofuran‐2‐yl)ethanone. The structures of the newly synthesized compounds were elucidated by elemental analysis, spectral data, chemical transformation, and alternative synthesis route whenever possible.     

Useful Precursors for Synthesis of Some New Azolo[3,4‐d]pyridiazines,Azolo[1,5‐a]pyrimidines,Azolo[5,1‐c]triazines,Pyrazoles, and Benzo[b][l,4]diazepine

Pyrazolo[3,4‐d]pyridazines, isoxazolo[3,4‐d]pyridazines, azolo[1,5‐a]pyrimidines, azolo[5,1‐c]triazines, pyrazoles, and benzo[b][l,4]diazepine were synthesized from the appropriate hydrazonoyl halides, hydroximoyl halides, heterocyclic amines, diazotized heterocyclic amines, arenediazonium chlorides, and o‐phenylenediamines with appropriate of sodium 3‐(5‐bromobenzofuran‐2‐yl)‐3‐oxoprop‐1‐en‐1‐olate or 1‐(5‐bromobenzofuran‐2‐yl)‐3‐(dimethylamino)prop‐2‐en‐1‐one. The newly synthesized compounds were elucidated by elemental analyses, spectral data, and alternative synthesis whenever possible.     

Tailoring of carboxyl‐decorated magnetic latex particles using seeded emulsion polymerization

In this research, submicron and carboxyl‐functionalized magnetic latex particles were elaborated by using seeded emulsion polymerization technique in presence of oil‐in‐water (o/w) magnetic emulsion as seed. The polymerization conditions were optimized in order to get well‐defined latex particles with magnetic core and polymer shell bearing carboxylic (–COOH) functionality. Starting from (o/w) magnetic emulsion as seed, synthesis process was performed by copolymerization of styrene (St) monomer with the cross‐linker divinylbenzene (DVB) in presence of 4,4′‐azobis(4‐cyanopentanoic acid) (ACPA) as a carboxyl‐bearing initiator. The prepared magnetic latex particles were first characterized in terms of particle size, chemical composition, morphology, magnetic properties, magnetic content, and colloidal stability using various techniques, e.g. particle size analyzer using dynamic light scattering (DLS) technique, Fourier transform infrared, transmission electron microscopy, vibrating sample magnetometer, thermogravimetric analysis, and zeta potential measurements as a function of pH of the dispersion media, respectively. The prepared magnetic latex particles were then used as second seed for further functionalization with methacrylic acid (MAA) in order to enhance carboxylic groups on the magnetic particle's surface. The results showed that final magnetic latex particles possessed spherical morphology with core‐shell structure and enriched carboxylic acid functionality. More importantly, they exhibited superparamagnetism with high magnetic content (58.42 wt%) and high colloidal stability, which considered as the main requirements for their application in the biomedical diagnostic domains. Copyright © 2017 John Wiley & Sons, Ltd.     

Synthesis of quantum dot-tagged submicrometer polystyrene particles by miniemulsion polymerization

Submicrometer fluorescent polystyrene (PS) particles have been synthesized via miniemulsion polymerization using CdSe/ZnS core-shell quantum dots (QDs). The influence of QD concentration, QD coating (either trioctylphosphine oxide (TOPO)-coated or vinyl-functionalized), and surfactant concentration on the polymerization kinetics and the photoluminescence properties of the prepared particles has been analyzed. Polymerization kinetics were not altered by the presence of QDs, whatever their surface coating. Latexes exhibited particle sizes ranging from 100 to 350 nm, depending on surfactant concentration, and a narrow particle size distribution was obtained in all cases. The fluorescence signal of the particles increased with the number of incorporated TOPO-coated QDs. The slight red shift of the emission maximum was correlated with phase separation between PS and QDs, which occurred during the polymerization, locating the QDs in the vicinity of the particle/water interface. QD-tagged particles displayed higher fluorescence intensity with TOPO-coated QDs compared to those with the vinyl moiety. The obtained fluorescent particles open up new opportunities for a variety of applications in biotechnology.