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The rheological properties of poly(trimethylene naphthalene-2,6-dicarboxylate) (PTN) were studied using a dynamic stress rheometer with oscillatory parallel plates. The influence of temperature and molecular weight on the storage modulus, loss modulus, and complex viscosity was investigated. It was possible to express the temperature dependence of the shift factors a T with the Arrhenius equation; the activation energy was found to be 85 kJ/mol. A comparison of molecular weight determined: (a) by rheological measurements and (b) by Mark–Houwink–Sakurada equation showed excellent agreement.

After a total monitored operational timescale of almost five years on long-term installations, both in the laboratory and in four nuclear power plants, evidence can be put forward that the DC-potential drop method is now, at its current stage of development, suitable for inspecting and monitoring material regions such as, e.g. weld seams in pipework, for crack initiation and crack growth at power plant temperatures. This function can be performed with reliability and high sensitivity. The inspection and monitoring of cracks on the internal surface of the pipework can also be carried out from the external surface. The studies have shown that the method is basically able to monitor the growth of cracks found at discontinuous intervals using permanently installed potential probes, i.e. from plant inspection to plant inspection, while a transition to continuous monitoring is possible at any time. Thus a measure of redundancy can be provided for conventional ultrasonic and radiographic inspection, in particular for difficult to check austenitic weld seams. The method can also be seen as an alternative to the conventional techniques. When necessary, the cracks found can be measured more accurately than was previously possible with conventional ultrasonic and radiographic inspections. The total exposure to radiation can be reduced in comparison to other methods of inspection.

Poly(trimethylene terephthalate) was synthesized on a semi-technical scale following the trans-esterification route. Ester exchange as well as polycondensation were catalyzed by titanium tetrabutylate. The polymer formed shows a remarkable degree of whiteness, contrary to poly(ethylene terephthalate) when synthesized with the aid of titanium compounds. Polymers having molar masses up to 70000 (weight average) were obtained suitable for melt spinning. The Mark-Houwink parameters for solutions in 1,1,2,2-tetrachloroethane/phenol (1 : 1, w/w) were determined using static light scattering as a calibration. The melt volume index (235°C, 1.2 kg) was typically in the range 20–30 mL/10 min for a polymer having a weight-average molar mass of 50000–60000 g mol−1. Poly(trimethylenterephthalat) wurde durch Umesterung von Dimethylterephthalat und Polykondensation im halbtechnischen Masstab hergestellt. Als Katalysator fur beide Reaktionsschritte wurde Titantetrabutylat eingesetzt. Die erhaltenen Polymeren mit gewichtsmittleren Molekulargewichten von bis zu 70000 konnen aus der Schmelze versponnen werden und zeigen, im Gegensatz zu mit Titanverbindungen hergestelltem Poly(ethylenterephthalat), einen bemerkenswerten Weisheitsgrad. Die Mark-Houwink-Parameter in 1,1,2,2-Tetrachlorethan/Phenol-Losung (1 : 1, w/w) wurden mit Kalibrierung durch statische Lichtstreuung bestimmt. Die MVI-Werte (235°C, 1,2 kg) lagen typischerweise zwischen 20 und 30 mL/10 min bei Polymeren mit einer gewichtsmittleren Molmasse von 50000–60000 g mol−1.

The present article addresses the dilute solution behavior of two different polyelectrolyte systems: Aqueous solutions of quaternized poly(2-vinylpyridines) and of polyacrylic acids. Firstly, it is demonstrated that the dimensions of the chains for all investigated polyelectrolytes are described by a model that explicitly considers (i) an excluded volume comprising contributions of the electrostatic interactions via the effective charge density, and (ii) the intrinsic excluded volume in terms of the Flory interaction parameter. The effect of the chain hydrophobicity and the type of counterions on the coil dimension of the chains and the effective charge density is discussed. The latter is compared with results obtained from osmotic pressure measurements and conductometry. The second part of the review is devoted to an investigation of the phase behavior of the two systems. For quaternized poly-2-vinylpyridines phase transitions are induced by addition of inert salt, typically Nal and are denoted as salting out and salting in. The phase behavior is assumed not to be influenced by ion specific interactions other than the Flory excluded volume parameter. Contrary, in case of polyacrylic acid highly specific interactions, such as complexation, between the polyion and bivalent earth alkaline cations may cause a precipitation of the polyelectrolyte. The precipitation point depends on both, the concentration of the polyions and the counter ions. Investigation of the coil dimensions by means of combined static and dynamic light scattering reveals a coil collapse towards spherical particles. Possible transition states along this shrinking process are discussed.

In the developed form described the direct current potential drop method is a reliable and relatively accurate procedure for the measuring and surveillance of surface cracks in metallic materials. There are also significant possibilities in practice of surveying cracks on the inaccessible side of the structure. The basis for the improvement in accuracy, in particular for short cracks, is firstly an improved measuring technique and secondly calibration curves determined using an electrolytic tank. Practical experience gained in conventional plants is to date positive. The opportunity exists of benefitting from the advantages that would be brought about by an increased use of the potential drop method in plant surveillance. In nuclear plants specifically this would achieve a reduction in the testing personnel's exposure to radiation.

Planar laser-induced predissociative fluorescence is applied to image state-specific densities of OH and hot O(2) inside an internal-combustion car engine. Improved instrumentation is described. It includes better imaging optics and a spectrometer that permits desired molecular quantum states to be selected and identified in real time. The OH (nu'' = 0) images are cleanly separated from the isooctane fuel and they display a thin superequilibrium region at the flame front. In contrast, vibrationally excited O(2) (nu'' = 6 or nu'' = 7) is uniformly distributed behind the front. Uneven and broken flame fronts are commonly observed.

Oppositely charged polyelectrolytes interact in solution, forming polyelectrolyte complexes, which often appear as gel-like precipitates. This kind of complex formation was studied by means of calorimetric and rheological measurements. The enthalpy effects, though being fairly small, give some information about the binding strength of counterions to the macroion. We studied the system poly(p-styrene sulfonate)/poly(trimethylammonium-2-ethyl methacrylate) (PSS-PTMA), varying systematically the low molar mass counterions of PSS. In every case, the maximum of enthalpy was found around a 1:1 (mol:mol monomer units) composition of the complexes, with the shape of enthalpy versus composition-curve indicating a stoichiometric interaction. The maximum enthalpy decreased with increasing atomic mass of the counterion when the alkaline metal salts of PSS were used and no change was made on the side of the cationic polyelectrolyte. The salts of the alkaline earth metals gave a distinctly higher enthalpy. On the contrary, viscosity measurements showed a very broad minimum as a function of composition, indicating that the formation of non-stoichiometric complexes is also occurring. The conclusion of these observations is that the complex formation is stoichiometric with respect to the monomeric units, but not necessarily stoichiometric with respect to the entire macromolecules.

Elasticity measurements performed on well-defined poly(dimethylsiloxane) networks (PDMS) reveal that there is a direct proportionality between the small-strain modulus, G, and the chemical network density, vch, only at high network densities, whereas G is quite constant and in the order of the plateau modulus, G N o , at low network densities. This indicates that topological interactions, e. g. entanglements, contribute to the modulus in a certain range of network densities.

The subject of this work is to determine the dynamic and static elastic properties of polymer networks and to compare the experimental results with theoretical predictions. It is found that poly(dimethylsiloxane) (PDMS) networks on the one hand and polyisoprene (IR) and natural rubber (NR) networks on the other hand show different behaviour in frequency dependence of the storage modulusG′ is observed in the range 10−3 − 1 Hz, contrary to IR or NR. The reason for this is the absence of entanglements in PDMS. Comparing the measured static moduli with those calculated by rubber elasticity theory, we found that the front factorA· /0 is near to 0.5 in case of PDMS, but near to I for IR/NR networks. Both parts of the front factor may possibly cause this difference. As the PDMS chains possess a relatively high mobility we can assume that fluctuations of the junction points are less restricted than in IR/NR. This causes a structure factor A smaller than 1 in agreement with Flory's recent theory. According to James and Guth, the network chains tend to contract during the crosslinking process. This will be more likely in the networks of entanglement-free, highly mobile PDMS chains than in IR or NR rubbers. Hence the memory term /0 is smaller for PDMS than for IR/NR. Both alternative explanations are based on the different mobility of the chains considered. It may be assumed that the front factor is influenced by both effects and not only by the fluctuations of crosslinks.

Ellipsometry has been used to study oxygen chemisorption and corrosive oxidation of aluminium single crystals in the pressure and temperature ranges 10 −9 −10 −2 Torr and 295–800 K respectively. Two oxidation stages have been identified. A fast initial stage was found to correspond to initial chemisorption and incorporation of oxygen and ends with the formation of a thin oxide layer via nucleation. An anomalous decrease in the ellipsometric parameter Ψ occurs during this stage. The second, slow stage corresponds to the growth of a parallel-sided oxide film; changes in both Δ and Ψ can be described classically using the Drude equations. In this region both logarithmic (500–600 K) and parabolic (650–800 K) oxidation kinetics were observed on the (111) surface. Logarithmic kinetics were accompanied by a pressure dependence of p 0.5 with oxide growth in the thickness range 5–20 A. Parabolic growth exhibited an activation energy of 113 ± 5 kJ mol −1 with film growth in the range 15–45 A.

Zum Einflus der Bandbreite und der Mittenfrequenz von Ultraschallimpulsen auf den Nachweis und die Bewertung von Fehlstellen in schallstreuenden Werkstoffen werden sowohl theoretische Grundlagen als auch Versuchsergebnisse vorgestellt. Beide weisen an Modellfehlern nach, das optimale Frequenzbereiche fur die Prufung im Ubergangsbereich von Reflexion zu Streuung existieren, sofern die Streuung der Werkstoffe im Rayleigh-Bereich liegt. Diese Bereiche lassen sich mit der CS-Technik (controlled signals) gezielt zur Anhebung der Signal/Rausch-Verhaltnisse, sowie zu einer verbesserten Fehlerbewertung ausnutzen. Die sich hieraus ergebende Vorgehensweise zur Optimierung der Impulsparameter bei der Prufung schallstreuender Werkstoffe wird vorgestellt und diskutiert. Basic Aspects to Improve Ultrasonic Signals by Means of the CS- Technique for Testing Coarse Grained Materials The influences of band width and centre frequency of ultrasonic pulses on the detection and evalution of defects in coarse grained materials are discussed. Theoretical calculations and experiments with artificial defects demonstrate the existence of optimum frequency ranges, within the transition range from reflection to scattering. By applying CS-pulses (controlled signals) these frequency ranges can be used in order to improve the signal-noise ratio. Guide-lines to optimize the pulses in ultrasonic testing of coarse grained materials are presented and discussed.

Effects of two different periods of fasting were studied on glucose tolerance and insulin response to glucose in genetically diabetic KK and nondiabetic C57BL/6J mice. Blood sugar levels of the KK mice did not differ markedly from those of the C57BL/6J mice at the fed state or after 8 h fasting. They were, however, significantly higher in the KK mice when fasted for 18 h. The serum IRI levels, which were at least twice as high in the KK mice, decreased more markedly after 18 h fasting. The KK mice showed impaired glucose tolerance after 8 h fasting, which became more pronounced after 18 h fasting. The insulin response to glucose in the KK mice was not altered after an 8-hour fast; it was, however, diminished greatly after an 18-hour fast. These data suggest that prolonged fasting is necessary to detect the diabetic traits in the KK mice. The C57BL/6J mice showed neither impaired glucose tolerance nor diminished insulin response to glucose at both periods of fasting. Studies with the F1 hybrids (KK male X C57BL/6J female), which carry half of the diabetic genes, suggest that the mode of inheritance of diabetes in the KK mice might be polygenic.

Improvements in ultrasonic testing of sound-scattering materials could be achieved if optimum pulse parameters for a particular material could be determined. This paper describes a theoretical model which shows optimum test frequencies exist in the scattering to reflection transition range of reflectors, and experimental measurements of the signal-to-noise ratio for several materials are presented which are in good agreement with this model.

The fabrication of photomasks for integrated optical (i.o.) components presents the particular difficulty of an extreme aspect ratio. It is shown that this problem can often be solved by a synthesizing procedure using a photorepeater. This method is demonstrated for two different versions of i.o. directional couplers (total length 20 mm, width of waveguides 3 μ, width of coupling gap between waveguides 3 μ). Single characteristic parts of the masks, which are composed on the reticle, are joined together by a step-and-repeat process. Residual imperfections of junctions can be neglected for diffused waveguides. Further advantages of the method (constant width of the waveguide and of the separating gap along the total length) are explained. Finally, the i.o. directional couplers produced are examined, and some of their characteristic parameters are described.

Zur Bestimmung der Grose von Korrosionsrissen bei der manuellen Ultraschallprufung wird ein Mehrfrequenzenverfahren erfolgreich eingesetzt. Dieses liefert – unabhangig von der absoluten Echoamplitude (Reflexionsfaktor) des Risses und ohne Einschrankungen hinsichtlich der axialen Auflosung – selbst bei geneigten Fehlern Genauigkeiten in der Tiefenbestimmung, die bisher speziell bei kleinen Ristiefen unter 2 mm nicht realisierbar waren. Beispiele werden vorgestellt und praktische Anwendungen diskutiert. Investigations to Determine the Size of Corrosion Cracks For determining the size of corrosion cracks with ultrasound a multifrequency test method is described. By applying this procedure corrosion cracks of a size smaller than 2 mm are correctly evaluated independent of their position and of the reflection factor. Examples are presented and discussed for some practical applications.

Es werden Untersuchungsergebnisse vorgestellt, die belegen, das Verfahren der Korrelationsanalyse (matched filter) in der Lage sind, die Nachweisempfindlichkeit von Reflektoren in schallstreuenden Werkstoffen zu verbessern. Es wird ein neues Konzept zur praktischen Durchfuhrung von Korrelationsanalysen erarbeitet, bei dem die Korrelationsfunktion bereits in CS-Sendeimpulsen enthalten ist. Die Messungen ergeben, das sich die Ergebnisse praktisch nicht von der wesentlich aufwendigeren empfangsseitigen Korrelationsanalyse unterscheiden. Als wesentlicher Vorteil ergibt sich, das die Prufgeschwindigkeit gegenuber der ublichen Ultraschallprufung nicht verringert wird. Application of cross correlation to grain scattering materials using controlled ultrasonic signals Investigations are presented which show, that cross correlation analysis (matched filter) enables to increase the flaw detection sensitivity of reflectors in grain scattering materials. The practical application of cross correlation techniques can drastically be simplified by using controlled signals which already include the correlation function. Measurements prove, that the results are in good agreement with the usual, more expensive correlation techniques. The main advantage is, that cross correlation with aid of CS-pulses can be achieved with the same speed as in conventional ultrasonic testing.

In earlier publications, we reported that the Japanese KK mouse develops human diabetic-like microangiopathy, namely glomerulosclerosis, retinopathy and peripheral gangrene due to small blood vessel disease. These studies were confirmed by other investigators. Diabetic glomerulosclerosis, which involves an excessive deposition of mesangial matrix, is a consistently demonstrable pathologic disorder in KK mice as early as 2 months of age. In older KK mice, the marked increase in the mesangial matrix results in the formation of glomerular nodules. Exudativelike glomerular lesions were also observed in these mice.

Serum alanine concentration was determined in nonpregnant and pregnant normal control Swiss albino (SA) and genetically diabetic KK mice. The serum alanine levels were significantly lower in nonpregnant KK than in nonpregnant SA mice. Fasting elicited hypoglycemia, hypoinsulinemia and hypoalaninemia in both groups of pregnant mice. Oral administration of alanine in nonpregnant and pregnant mice resulted in a significant rise in blood sugar levels within 15 min in both groups. However, the initial blood sugar response to oral alanine was greater in pregnant than in nonpregnant mice. This increase in blood sugar response to exogenous alanine appears to be mediated by glucagon. The data suggest that pregnancy elicits hypoglycemia, hypoinsulinemia and hypoalaninemia in both nondiabetic and diabetic mice.

In previous communications, we described specific glomerular changes in genetically diabetic KK mice (1–4). These changes include an increase in mesangial matrix and thickening of the glomerular basement membrane. Increase in the mesangium was found as early as two months of age, which gradually progressed with aging (3–4). Similar findings were described by other investigators.

By applying the CS-technique it is possible to consider and to balance frequency dependent transfer functions of workpieces leading in many cases to optimized test conditions. The application of this technique to scattering materials is demonstrated regarding both the improvement of the signal-to-noise ratio and the improvement of the axial resolution. Some results are presented and discussed.