Zur unverträglichkeit von polymergemischen. III. Lichtstreuungsmessungen an hochmolekularen polystyrolen in polymethylmethacrylat/benzol

Polystyrenes of high molecular weight were investigated by means of light scattering in the isorefractive polymer/solvent mixture polymethylmethacrylate/benzene. It was found, that the second osmotic virial coefficient, A₂, was strongly dependent on the molecular weight and the concentration of polymethylmethacrylate (PMMA) but neglegibly on the molecular-weight of polystyrenes (PS) or on the temperature between 20 and 60°C. A plot of A₂/A vs. c_PMMA/c_Θ revealed that all points fall on a common line for all molecular weights of PS and PMMA. Herein A means the second osmotic virial coefficient of PS in pure benzene, c_PMMA the concentration of PMMA, and c_Θ the concentration of PMMA at the Θ-point (A₂ + 0). This result could be theoretically interpreted in terms of the STOCKMAYER light scattering theory for multicomponent systems. The radii of gyration of PS in PMMA/benzene decrease with increasing concentration of PMMA. Furthermore, these radii increase slightly with increasing molecular weight of PMMA at the Θ-point. The coil dimensions, however, are generally bigger than those found in binary Θ-systems. For the measured radii of gyration of PS in PMMA/benzene a common line for all molecular weights of PS and PMMA could be found by normalizing with respect to both the radii of gyration and the concentration of PMMA.     

Analyse von polystyrolharzen mit funktionellen gruppen mittels IR-spektroskopie und pyrolyse-gaschromatographie-massenspektroskopie

Styrene-divinylbenzene copolymers having functional groups ? CH₂X [X?H, Cl, J, OCOCH₃, OH, OC₂H₅, NH₂, NHC₂H₅, N(C₂H₅)₂, CN, C(?NOH)NH₂, NCS, COC₂H₅, (CH₂)₃CH₃] in para position were analysed qualitatively by the combination of infrared data with results of curiepyrolysis-gaschromatography-mass spectroscopy. The determination of structure was possible in all examples by direct or indirect statements at least of one of both methods. Some evidences were completed by a “thermolysis” at 400°C.     

Über die verträglichkeit von copolymeren mit den entsprechenden homopolymeren

Two polymers being generally incompatible, it was interesting to examine if compatibility of two homopolymers can be realized by addition of a corresponding: graft, block, or random copolymer. Our study was limited to two systems of atactic polymers: polystyrene-polymethacrylate and polystyrene-1,4 cis polyisopren, mainly because no crystallisation is observed in this case at common temperatures. For mixtures of copolymers and homopolymers in the solid state, it is possible by examination of films, obtained by solution evaporation, to determine the limits of the compatibility region and the most important corresponding parameters, that is composition of the mixture, molecular weight, and structure of the copolymer. Ternary diagrams, for mixtures of two homopolymers and a copolymer, show that only block copolymers are able to achieve better compatibility, especially if their composition is near 50:50 and if molecular weight of the homopolymers is lower than those of block copolymers. Graft and random copolymers however have practically less or no effect on compatibility. Further for the system polystyrene–polyisopren and the corresponding block-copolymer, the relation between compatibility and shock resistance has been shown.     

Der Nachweis von Heparin in den basophilen Leukocyten

Ohne Zusammenfassung     

Der Nachweis von Calcium-Phosphat in der Herzmuskulatur mittels Röntgenmikroanalyse

Zusammenfassung Die Herzmuskulatur von myopathischen Hamstern wurde mittels energiedispersiver Röntgenmikroanalyse untersucht. Das integrale Röntgenspektrum ergab hohe peaks im Bereiche der K-Linie des Phosphors und des Calciums. Für diese beiden Elemente wurde anschließend mit line scan die Lokalisation im Gewebe ermittelt. Es wurde dabei für beide Elemente eine hohe Zählrate im Bereich von lichtmikroskopisch sichtbaren Mineralsalzablagerungen gemessen. Aus den Untersuchungen geht hervor, daß es mit der energiedispersiven Röntgenmikroanalyse in kurzer Zeit möglich ist, eindeutige Aufschlüsse über Ablagerungen von Elementen mit einer Ordnungszahl größer als 11 im Gewebe zu erhalten.

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The detection of calcium phosphate in the myocardium by X-ray microanalysis

Summary The myocardia of myopathic hamsters were examined by means of energy-dispersive X-ray microanalysis. The integrated X-ray spectrum exhibits high peaks in the range of the K-lines for phosphate and for calcium. The localization of these elements in the tissue was subsequently established by line scan. A high counting rate for both elements was detected in the area of the mineral salt deposits visible by light microscopy. The studies establish the possibility of detecting deposits of foreign substances consisting of elements with a higher number than 11 in the table of elements quickly and accurately by energy-dispersive X-ray microanalysis.

     

Nachweis von Reticulocyten und plastische Darstellung der Blutzellen mittels Reflexionskontrast

Zusammenfassung Mit dem Reflexionskontrastverfahren, als Zusatzeinrichtung eines Auflichtmikroskops, lassen sich in Giemsa- oder Pappenheim-gefärbten Blutausstrichen Reticulocyten von reifen Erythrocyten unterscheiden. Das Oberflächenrelief der roten Blutzellen ist quantitativ analysierbar und ist bei Schrägbeleuchtung, nach Dezentrierung der Zentralblende, plastisch sichtbar. Reticulocyten sind um etwa 15% größer, zeigen seltener Abweichungen von der Kreisform und eine weniger tiefe zentrale Eindellung als reife Erythrocyten. In supravital mit Brillantkresylblau gefärbten Präparaten sind im Reflexionskontrast um 72% mehr Erythrocyten als Reticulocyten zu diagnostizieren als im Hellfeld.     

Die chemische heterogenität von copolymerisaten. 4. Experimentelle untersuchungen zur verträglichkeit

Two chemically homogeneous methyl methacrylate/butyl acrylate copolymers form optically homogeneous (i.e. clear) mixtures in bulk only if the difference in their methyl methacrylate content does not exceed 10–20 mole-%. As torsional vibration experiments show, the mechanical homogeneity limit occurs at the same difference in the methyl methacrylate content. In inhomogeneous systems of two homogeneous copolymers these are found two corresponding damping maxima. Electron micrographs show the presence of structures of the order of magnitude of 30 Å even in some optically or mechanically homogeneous systems. The phase size increase suddenly near the turbidity limit. In mixtures of three components, the copolymer with a composition which lies in the middle does not aid compatibility. In copolymers with broad continuous chemical distributions microphases are formed from mutually compatible macromolecules. Optical and mechanical homogeneity or inhomogeneity is then a question of the size of the individual microphases. Suppression of transfer reactions in the polymer leads to an increase in the size of the microphases, while the size decreases when these reactions are encouraged. In agreement with this, graft copolymerization has a homogenizing effect. Preliminary experiments on copolymers of other monomers indicate that these observations are generally valid.     

Proliferationsbestimmung beim Mammakarzinom durch den immunhistochemischen Nachweis von Ki-67

Gene expression profiling has demonstrated the prognostic relevance of genes associated with proliferation in breast cancer. The immunohistochemical marker Ki-67 enables routine assessment of proliferation activity in pathology. In a number of retrospective but only few prospective studies the prognostic relevance of Ki-67 in breast cancer could be shown. Although there is no standardized approach with regard to which area of a histological section and how many cells should be counted in a quantitative or semiquantitative fashion as well as to the threshold, Ki-67 is broadly applied in breast pathology. This can be explained by the good reproducibility of the degree of proliferation assessed by Ki-67, at least in the low and high ranges, the possibility to substantiate grading and better practicability in core biopsies in comparison to mitotic counting. In neoadjuvant therapy of hormone receptor positive breast cancer, Ki-67 can probably predict the efficacy of pure hormone receptor blockade without chemotherapy.     

Über den ersten Nachweis von Trichinella spiralis (Owen) in Afghanistan

Ohne ZusammenfassungMit 5 TextabbildungenHerrn Professor Dr. Dr. R. Lehmensick danke ich herzlich für die freundliche Durchsicht des Manuskriptes.     

Nachweis des di-2-cyanoisopropylperoxides bei der zersetzung von azoisobuttersäuredinitril in gegenwart von sauerstoff

Di-2-cyanoisopropylperoxide is formed when azobisisobutyronitrile is decomposed under oxygen in isobutyronitrile as a solvent. The yield amounts to ca. 5%. Thermal decomposition of the peroxide occurs with measurable rate only above 120°C by a first order reaction. The energy of activation in cumene as a solvent was found to be 37.9 kcal · mole^?1. The rate constant of the decomposition reaction at 140°C amounts to 0.057 h^?1 in cumene, to 0.073 h^?1 in tert-butylbenzene, to 0.18 h^?1 in chlorobenzene, and to 0.23 h^?1 in o-dichlorobenzene.     

Nachweis einer Fructokinase und ihre Bedeutung für den Stoffwechsel von Pseudomonas syringae pv. phaseolicola

The plant pathogenic Pseudomonas syringae pv. phaseolicola possesses a fructokinase which is epigenetically regulated. The k_M values for fructose and ATP are 0.56 and 0.53 mM, respectively. About 23% of the activity observed with ATP was obtained with equimolar amounts of ITP. CTP, GTP, UTP, PEP and acetl-P were ineffective, Fructokinase is responsible for the conversion of fructose to fructose-6-phosphate. In this way,. fructose, which is formed intracellulary during the growth in a sucrose or mannose containing medium, can be metabvolized via fructose-6-phosphate.     

Nachweis des M-Proteins von Streptococcus pyogenes auf der Zelloberfläche durch Immun-Gefrierätzung

By combination of indirect immunoferritin technique and freeze-etching (immuno freeze-etching) M-protein of Streptococcus pyogenes was demonstrated on the surface of the bacterial cells. The distribution of the ferritin particles shows that the antigen is bound on thread-like structures. The results correspond to the localization of the M-protein observed in ultrathin sections from the same material.     

Erfahrungen über den Nachweis von Bact. coli im Wasser mit Membranfilter

Zusammenfassung Membranfilter nachZsigmondy-Bachmann von 4 cm Durchmesser eigneten sich im Stefi-Apparat zur Abfilterung von Colikeimen aus Wasserproben. Nach Auflage der Filter auf Endoplatten entwickeln sich die Keime zu zählbaren Kolonien mit typischem Fuchsinglanz.Vergleichsbestimmungen mit dem Anreicherungsverfahren nachEijkman erweisen die Zuverlässigkeit der neuen Filtermethode und ihre Vorzüge. Sie ist insbesondere für Serienuntersuchungen auf Bact. coli wegen ihrer Schnelligkeit, Zuverlässigkeit und ihres sparsamen Materialverbrauchs zu empfehlen.