On the synthesis of poly(ε-caprolactam)—poly(butadiene-co-acrylonitrile) block copolymers for the reaction injection molding process

The liquid rubbers Hycar ATBN and HTBN were used in the preparation of poly(ε-caprolactam)—poly(butadiene-co-acrylonitrile) block copolymers intended for reaction injection molding by the anionic polymerization of ε-caprolactam. The conversion of Hycar end groups to polymerization growth centers and the conditions of polymerization influence the crystallization, morphology, and mechanical properties of the product through its molecular structure. The contribution of individual reactions to this molecular structure is discussed.     

Free-radical ring-opening polymerization of 2-(o-chlorophenyl)-4-methylene-1,3-dioxolane

2-(o-chlorophenyl)-4-methylene-1,3-dioxolane was synthesized and polymerized in presence of AIBN or by use of benzoin methyl ether as photosensitizer. Based on the analysis of the resulting polymers, a polymerization mechanism was proposed.     

Herstellung von Fahrbenzin aus Kohle oder Erdgas

Production of petrol from coal and natural gas . This article assumes an adequate knowledge of the Fischer-Tropsch process in its original form and as its modern variant, the Synthol process, and adopts the view that coal hydrogenation will only become implementable on an industrial scale in the early 1990. In detail, it considers the integration of the Mobil MTG process in the proven area of methanol production; operation of pilot plant has shown that this process is indeed suitable for industrial scale operation. The production of methanol from natural gas and coal is discussed, as is the subsequent conversion of methanol to petrol; emphasis is placed on the best possible integration of all process plant. Apart from the conventional steam reforming route for methanol production from natural gas, the alternative approach of combing a steam reforming plant with an autothermal cleavage step is also considered; the latter leads to a significant increase in efficiency and a reduction in investment costs. It is also shown for coal as raw material that simultaneous generation of petrol and SNG has considerable advantages of a thermal and financial nature. The principal process steps are described after the manner of keywords and the product costs are presented as functions of the various raw material costs.     

Properties of magnetic poly(glycidyl methacrylate) and poly(N-isopropylacrylamide) microspheres

Iron oxide colloids were prepared by coprecipitation of Fe(II) and Fe(III) salts in alkaline media and stabilized by perchloric acid, oleic acid, or poly(acrylic acid). In an attempt to obtain magnetic polymer microspheres differing in size, dispersion polymerization of glycidyl methacrylate (GMA) in ethanol containing HClO₄-stabilized magnetite, dispersion copolymerization of GMA and 2-hydroxyethyl methacrylate (HEMA) in toluene/2-methylpropan-1-ol mixture in the presence of oleic acid-coated magnetite, and inverse suspension copolymerization of N-isopropylacrylamide (NIPAAm) and N,N′-methylenebisacrylamide (MBAAm) in cyclohexane in the presence of poly(acrylic acid)-coated maghemite were compared. The microspheres were characterized by morphology, size, polydispersity, and some magnetic properties.     

"Multicolor" electrochemical labeling of DNA hybridization probes with osmium tetroxide complexes

Labeling of oligonucleotide reporter probes (RP) with electroactive markers has frequently been utilized in electrochemical detection of DNA hybridization. Osmium tetroxide complexes with tertiary amines (Os,L) bind covalently to pyrimidine (predominantly thymine) bases in DNA, forming stable, electrochemically active adducts. We propose a technique of electrochemical "multicolor" DNA coding based on RP labeling with Os,L markers involving different nitrogenous ligands (such as 2,2' -bipyridine, 1,10-phenanthroline derivatives or N,N,N',N'-tetramethylethylenediamine). At carbon electrodes the Os,L-labeled RPs produce specific signals, with the potentials of these differing depending on the ligand type. When using Os,L markers providing sufficiently large differences in their peak potentials, parallel analysis of multiple target DNA sequences can easily be performed via DNA hybridization at magnetic beads followed by voltammetric detection at carbon electrodes. Os,L labeling of oligonucleotide probes comprising a segment complementary to target DNA and an oligo(T) tail (to be modified with the osmium complex) does not require any organic chemistry facilities and can be achieved in any molecular biological laboratory. We also for the first time show that this technology can be used for labeling of oligonucleotide probes hybridizing with target DNAs that contain both purine and pyrimidine bases.     

Chiral separation of alkylamine antihistamines in pharmaceuticals by capillary isotachophoresis with charged cyclodextrin

Cyclodextrin-mediated capillary isotachophoresis (ITP) in cationic regime of the separation was developed for the separation and quantitation of alkylamine antihistamine dimethindene (DIM) and pheniramine (PHM) enantiomers in various pharmaceutical preparations (capsules, oral drops, gel, granulated powder). Several electrolyte systems of different compositions and pH were examined. The optimized chiral ITP electrolyte system was consisted of 10 mmol/L potassium acetate adjusted to pH 4.8 with acetic acid, containing 4 mmol/L negatively charged CE-β-CD (chiral selector) as the leading electrolyte with electroosmotic flow (EOF) suppressing additive, 0.2% (w/v) methylhydroxyethylcellulose (m-HEC), and 5 mmol/L β-alanine as the terminating electrolyte. The proposed electrophoretic method was successfully validated. It was convenient for the sensitive, simple, rapid, and highly reproducible assay of these antihistamine enantiomers. The calibration graphs relating the ITP zone length to the concentration of DIM and PHM enantiomers were rectilinear (r = 0.999) in the range 40.0-200.0 mg/L of each enantiomer. The relative standard deviations (RSD) were 0.75% for DIM(1), 0.63% for DIM(2), 1.05% for PHM(1), and 0.83% for PHM(2) (n = 6) when determining 100 mg/L DIM and PHM, respectively, standard solutions. According to the validation procedure based on the standard addition technique the recoveries were 97.66-98.34%. Good quantitation was obtained in short analysis time (a single analysis took about 12 min). The minimal sample pretreatment and low running costs make the proposed ITP method a good alternative to commonly used analytical methods (CZE, HPLC). The obtained results suggest that the proposed method is suitable for routine assay of dimethindene and pheniramine enantiomers in various pharmaceuticals.     

Partial Evaporation of Strontium Zirconate During Atmospheric Plasma Spraying

Perovskite-type SrZrO₃ has been investigated as a candidate material for thermal barrier coating application. During plasma spraying of SrZrO₃, SrO volatilized more than ZrO₂ and the coating composition deviates from initial stoichiometry. In this investigation, partial evaporation was investigated by spraying SrZrO₃ powders into water. The influences of spraying current, distance and particle size of the powder on the partial evaporation were also investigated in a quantitative way. With optimized spraying parameters, stoichiometric SrZrO₃ coating was produced by adding an excess amount of Sr in the precursors before plasma spraying to compensate for the volatilized component.     

Wind-Induced Peak Bending Moments in Low-Rise Building Frames

We present a procedure for estimating peaks of non-Gaussian processes representing fluctuating internal forces induced by wind in low-rise building frames. The procedure is designed for inclusion in computer programs that use surface pressure databases to obtain peak internal forces in frames. In general, the processes of interest are non-Gaussian, and we apply translation models to estimate the distribution of their peaks. To illustrate the procedure we calibrate a translation model to the record of a 1 h time history of the bending moment at the upwind bent of a low-rise frame.     

Properties of yeast free bread produced by supercritical fluid extrusion (SCFX) and vacuum baking

A novel technology, supercritical fluid extrusion (SCFX), allows for continuous production of yeast-free dough leavened via incorporation of supercritical carbon dioxide (SC-CO₂). In this study, an optimum dough formulation, SCFX leavened dough production and baking procedures were developed. A premixed dough was leavened by 1% (feed basis) SC-CO₂ injection in a twin screw extruder at 37 °C. Specific mechanical energy input was 18 kW h/ton. SCFX leavened dough and bread density, moisture content, bake loss, texture profile analysis (TPA) and stress relaxation were evaluated and compared to conventional yeast leavened breads throughout 5-day storage. A combination of vacuum and conventional baking yielded the lowest SCFX leavened bread density of 0.19 g/cm³ and crumb hardness comparable to conventional yeast leavened and commercial products. This approach could be beneficial for a continuous production of consistent ready-to-bake dough and breads having equivalent quality to commercial products but produced in shorter time and without ethanol emission issues.

Industrial relevance

The dough leavening process in conventional bread production is an industrial hurdle for a number of reasons. First, it is very time consuming. Dough leavening through yeast fermentation can take up to eight hours, which is not conducive to high production rates. This long waiting period also means a great deal of storage space is required to produce a large amount of dough. This storage environment must be carefully controlled in terms of temperature, humidity, and air conditions in order to maintain optimal yeast fermentation, which can also be very costly. Finally, the emission of ethanol, a significant byproduct of yeast fermentation, must be controlled according to the EPA clean air act. Expensive catalytic converters must be installed and maintained in commercial bread production facilities.Bread produced by super critical fluid extrusion (SCFX) overcomes these problems. Total dough production time is less than an hour, and with the proper baking equipment, the entire process can be made continuous. This means constant output, less downtime, and none of the costly storage space used for conventional dough proofing. Furthermore, since there is no yeast being used, there is no ethanol being produced. This means no harmful volatile organic emissions and no expensive catalytic converter. Coupled with vacuum baking, this process results in bread with qualities similar to commercially produced bread in significantly less time.