Polymerized mixed aggregates containing gadolinium complex and CCK8 peptide

Two novel amphiphilic unimers containing an aliphatic hydrophobic chain (PDA) with two C≡C triple bonds and hydrophilic heads presenting the chelating agent DTPAGlu and the CCK8 bioactive peptide, respectively, have been prepared by solid phase synthesis. Aggregates obtained by mixing together PDA-DTPAGlu, or its Gd(III) complex, and PDA-L2-CCK8 in 70/30 molar ratio before and after a polymerization process carried out by UV irradiation have been structurally characterized by means of small angle neutron scattering. The relaxivity properties of aggregates containing Gadolinium complexes have also been investigated. Elongated mixed micelles have been observed, in which the relaxivity value r _1p for each Gadolinium complex, measured at 20 MHz and 298 K, is around 12 mM^–1 s^–1.     

Hydrophilic alcohol ethoxylates as efficiency boosters for microemulsions

Highly amphiphilic polyalkane-PEO diblock copolymers drastically increase the solubilization capacity of surfactants in microemulsions if they are used in small quantities as additive to the surfactant. This effect goes along with an additional reduction of the already very low interfacial tension between water and oil. Lamellar phases, which usually develop when the surfactant becomes more efficient, are suppressed to a large extent. In this work we use another type of additive, namely hydrophilic alcohol ethoxylates. These amphiphiles are identical with the previously used block copolymers with respect to the hydrophilic moiety. However, they contain only small hydrocarbon groups ranging from C8 to C18. A typical example from the hydrophilic alcohol ethoxylates is C12E100. Both additive types increase surfactant efficiency equally with respect to mass fraction in the mixture. Because the alcohol ethoxylate additives decorate the surfactant film only on the aqueous side, they influence the curvature of the surfactant membrane or, in other words, the temperature behavior of the microemulsion. Together with nonionic surfactants, however, the shift of the one-phase region to higher temperatures is only a few degrees Celsius. Just as with the polyalkane-PEO block copolymers, the hydrophilic alcohol ethoxylates suppress lamellar phases. This behavior is especially pronounced if the hydrophobic groups are small or the PEO chains are long. We found that hydrophobic units as short as C 8 are sufficient to largely anchor the PEO chains at the interface. If C12 or C18 hydrocarbon unit are used instead, the PEO chains are fully interfacially active, even if the hydrophilic chain contains up to about 500 EO units. We applied the new additives in bicontinuous and in droplet microemulsions and used nonionic, as well as ionic, surfactants, namely C10E4 and AOT. In contrast to polyalkane-PEO blockcopolymers the new additives are easy to synthesize and are commercially available. Therefore, they might be interesting in applications.     

Highly Asymmetric Phase Diagram of a Poly(1,2‐octylene oxide)–Poly(ethylene oxide) Diblock Copolymer System Comprising a Brush‐Like Poly(1,2‐octylene oxide) Block

The phase diagram of a series of poly(1,2‐octylene oxide)–poly(ethylene oxide) (POO–PEO) diblock copolymers is determined by small‐angle X‐ray scattering. The Flory–Huggins interaction parameter was measured by small‐angle neutron scattering. The phase diagram is highly asymmetric due to large conformational asymmetry that results from the hexyl side chains in the POO block. Non‐lamellar phases (hexagonal and gyroid) are observed near f_PEO = 0.5, and the lamellar phase is observed for f_PEO ≥ 0.5.

     

Just noticeable differences of open quotient and asymmetry coefficient in singing voice

This study aims to explore the perceptual relevance of the variations of glottal flow parameters and to what extent a small variation can be detected. Just Noticeable Differences (JNDs) have been measured for three values of open quotient (0.4, 0.6, and 0.8) and two values of asymmetry coefficient (2/3 and 0.8), and the effect of changes of vowel, pitch, vibrato, and amplitude parameters has been tested. Two main groups of subjects have been analyzed: a group of 20 untrained subjects and a group of 10 trained subjects. The results show that the JND for open quotient is highly dependent on the target value: an increase of the JND is noticed when the open quotient target value is increased. The relative JND is constant: ΔO_q/O_q = 14% for the untrained and 10% for the trained. In the same way, the JND for asymmetry coefficient is also slightly dependent on the target value–an increase of the asymmetry coefficient value leads to a decrease of the JND. The results show that there is no effect from the selected vowel or frequency (two values have been tested), but that the addition of a vibrato has a small effect on the JND of open quotient. The choice of an amplitude parameter also has a great effect on the JND of open quotient.     

Turbidimetrischer Alcianblau-Test zur Messung von Glykosaminoglykan (GAG)-Abbauprodukten im menschlichen Urin

Ohne Zusammenfassung

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Turbidimetric alcian blue test for the determination of glycosaminoglycan degradation products in human urine

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Diese Untersuchungen wurden von der Deutschen Forschungsgemeinschaft unterstüzt.     

Zur Kenntnis der Schmelzdiagramme gesättigter Fettsäuren

Zusammenfassung Im Schmelzdiagramm von Palmitinsäure: Stearinsäure wurde auf mikroskopischem Wege das Auftreten dreier Mischkristallphasen festgestellt, wovon die Mischphase des mittleren Konzentrationsbereiches nicht wie bisher in der Regel üblich als Verbindung, sondern als stabilisierte Zwischenphase betrachtet wird. Der für das genannte System gefundene Aufbau des Diagramms gilt im allgemeinen für alle Systeme geradzahliger gesättigter Fettsäuren, die sich in ihrer Kettenlänge um 2 bis 4 C-Atome unterscheiden.

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Summary By microscopic procedure the fusion diagram of palmitic acid: stearic acid was shown to contain three mixed crystal phases. The mixed crystal phase of the middle concentration ranges is to be considered not a compound, as was the former belief, but rather as a stabilized intermediate phase. The structure of the diagram found for this particular system holds in general for all systems of even-numbered saturated fatty acids, which differ by 2 to 4 carbon atoms in their chain lengths.

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Résumé On montre microscopiquement, dans le diagramme de fusion acide stéarique-acide palmitique, l'existence de trois sortes de cristaux mixtes dont la phase mixte du domaine de concentration intermédiaire est considérée comme une phase stable intermédiaire, mais pas comme un composé, étant jusqu'ici considérée en règle générale. La structure trouvée pour le diagramme ci-dessus s'accorde, en général, avec tous les systèmes d'acides gras saturés à nombre pair qui diffèrent par deux à quatre atomes de carbone.

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Herrn Universitätsprofessor Dr.L. Ebert zum 60. Geburtstag gewidmet.