Modification reactions on thermotropic liquid-crystalline poly(ethylene terephthalate-co-oxybenzoate)s with bi- and trivalent 2-oxazoline couplers

Carboxy-terminated liquid-crystalline poly(ethylene terephthalate-co-oxybenzoate)s with 60 and 75 mol-% oxybenzoate units were modified with phenyl-1,4-bis(2-oxazoline) and phenyl-1,3,5-tris(2-oxazoline) in plasticorder and extruder. The modification gave rise to significant increase in molecular weights and also slight crosslinking and branching. The course of the reaction was followed by means of torque-vs.-time curves measured during the plasticorder modification. In spite of strong increase in melt viscosities the processability of the modified copolyesters was not worsened. Samples were injection-moulded and tested. Modifications improved the mechanical properties, distinctly. Especially, samples which were slightly crosslinked with phenyl-1,3,5-tris(2-oxazoline) demonstrated outstanding tensile and impact strengths. Significant differences in fracture behaviour could be evidenced by recording impact bending tests.     

Biologische Abwasserreinigungsanlagen

Biological sewage purification plants . In biological sewage purification plants the organic pollutants dissolved in the wastewater are decomposed by bacteria. For the aerobic bacterial metabolism, oxygen and, if necessary, nutrients are fed into the wastewater. For the bio-aeration step in biological sewage purification plants there has been a departure from shallow tanks (water depth 3 to 4 m) with surface aeration and a tendency to deeper tanks requiring installation of underwater pressure-aerating systems, particularly in the industrial sector. The most recent developments are characterized by above ground plant construction (tank construction) with water-depths between 15 and 30 m or by subterranean installations (pipes going down to 100 m). Decisive attempts are made to reduce the amounts of spent air, to save space, to minimize the problems of objectionable odours and sound, and to cut down investment and power costs as far as possible. In order to increase the capacity-time efficiency, to improve accomodation of sudden loading, and to increase the degree of decomposition, more attention is devoted to process control engineering aspects regarding completely mixed reaction space, cascade mode of operation, or tube characteristics. Besides air, pure oxygen is also used for aeration. For particularly critical wastewaters, activated carbon, either in powder or granular form, can be employed. For nitrogen-containing wastewaters a denitrification step is incorporated. The relevant processes and plants currently in use are discussed.     

Synthesis of N-(2-carboxy-thieno(2,3-b)pyridin-3-yl)-formamidines corresponding alkyl esters with antianaphylactic activity

A lot of N-(2-carboxy-thieno[2,3-b]pyridin-3-yl)formamidines especially in form of their amine salts--were synthesized by reaction of 3-amino-thieno[2,3-b]pyridine-2-carboxylic acids with dimethylformamide/phosphoroxide chloride or by reaction of 4-oxo-4H-pyrido[3',2':4,5]thieno[3,2-d]1,3- oxazines with amines. Carboxylic acid alkylesters of this structure were yielded from 3-amino-thieno[2,3-b]pyridine-2-carbonic acid alkylesters by reaction with dimethylformamide/phosphoroxide chloride or with N-formyl-piperidine or N-formyl-morpholine and phosphoroxide chloride. The compounds showed antianaphylactic activity.     

Messung des piezoelektrischen Effektes an stoßbelasteten Gesteinsstäben

Measurements of the piezoelectric effect of impact loaded rock bars The piezoelectric effect, which causes electric charge at the surface of impact loaded rock bars, is shown by measurements using electrodes. Moreover, electric field of this charge leads to measuring with antenna. The one-dimensional theory of elastic waves in bars is the theoretical basis of computation. The comparison of all the experimentally and numerically determined data has proven a good agreement of typical features of mechanical waves measured by used methods. The electric charge and the antenna signal are measurable on the front surface and on the lateral surfaces of samples. For using later measuring points needs a certain relation between wave length and sensor length. With respect of material of used granite samples the essential requirements are piezoelectrically active rocks. These properties dont depend on quartz content alone. So the piezoelectric effect enables to measure mechanical stress waves by transducer(antenna)which is not physically in contact with the appropriated rock sample.     

Comparison of the coupling behaviour of diisocyanate and bisoxazolines in modification of liquid crystalline poly(ethylene terephthalate-co-oxybenzoate)s

Methylene-4,4′-diphenyldiisocyanate and two different bisoxazolines were used for coupling reactions in carboxy-terminated liquid crystalline poly(ethylene terephthalate-co-oxybenzoate). In order to guarantee defined conditions, copolyesters with different carboxylic group concentrations were synthesized. The determination of the carboxylic group content is described. The coupling behaviour of both types of chain extenders has been compared. It was evidenced that the bisoxazolines reacted significantly faster than the diisocyanate. A slight excess of bisoxazoline in the reaction mixture prevented thermomechanical degradation. Depending on the amount of coupling agent added, an oxazoline termination of the copolyester was observed. Additionally, probable crosslinking reactions and the thermal stability have been discussed.     

乳清制品及其在肉制品中的应用

乳清制品作为优质的蛋白质来源受到人们的广泛关注,文中就乳清蛋白的主要生产工艺及其营养功能应用进行了分析探讨,并针对其在肉制品方面的特性进行了阐述。以国外肉制品生产企业应用乳清蛋白的典型产品为例,进一步阐述了目前乳清蛋白在我国肉制品行业应用的可行性和必然性     

Ensuring the long-term functionality of passive auto-catalytic recombiners under operational containment atmosphere conditions—An interdisciplinary investigation

In order to sustain the structural integrity of the containment and other safety relevant components i.e. to avoid a detonation of the hydrogen-air mixture generated during a severe accident in light water reactors, passive auto-catalytic recombiners (PAR) are used for hydrogen removal in many European nuclear power plants (NPP). In 1999, the German NPP Emsland (KKE) was equipped with 58 PAR of AREVA design as an internal accident management measure for a beyond-design accident. Since that time the recombiners are in a stand-by state. As the catalyst elements are exposed to various airborne substances during normal plant operation their function is controlled periodically by testing selected catalyst sheets in a specially designed device. Under the conservative test conditions during this procedure some catalyst sheets showed a delayed responding behavior. First internal analysis gave indication of a beginning fouling on the catalytic surface.The aim of a precautionary investigation performed in cooperation between KKE, Forschungszentrum Juelich and RWTH Aachen University was to characterize the composition of the fouling and to correlate it with potential sources within the containment.In the framework of the investigation the reports of the periodic inspections were analyzed and appropriate sample sheets were selected from the installation. These samples were subjected to a comprehensive chemical surface analysis in order to identify effects like thermal sintering, poisoning or a blocking of the catalytic surface (Baerns, M., 2004. Basic Principles in Applied Catalysis, Springer Verlag). Along with the chemical analysis the catalytic activity of the samples was assessed in several test series in order to correlate the chemically quantified deposition on the catalyst samples with the characteristics of the start-up and the steady-state performance of the recombination reaction. In a final step, possible sources of the fouling were analyzed with regard to their possible contribution to the phenomena. According to the results achieved, measures have been implemented at KKE in order to optimize procedures and to enhance the performance of the PARs.     

Development of low-loss sapphire mirrors

We report on the successful development of low-loss sapphire mirrors for use at a 1-mum wavelength. Methods for polishing and coating are described. The analysis of each process shows a roughness of better than 0.1 nm, a coating scattering of 1 ppm, and a surface scattering of 13 ppm. The mirrors have been characterized in a Fabry-Perot cavity, having a finesse of 100, 000. Mode doublets result from the birefringence of the coatings.