Atomic level analysis of biomolecules by the scanning atom probe

Utilizing the unique features of the scanning atom probe (SAP) the binding states of the biomolecules, leucine and methionine, are investigated at atomic level. The molecules are mass analyzed by detecting a single atom and/or clustering atoms field evaporated from a specimen surface. Since the field evaporation is a static process, the evaporated clustering atoms are closely related with the binding between atoms forming the molecules. For example, many thiophene radicals are detected when polythiophene is mass analyzed by the SAP. In the present study the specimens are prepared by immersing a micro cotton ball of single walled carbon nanotubes (SWCNT) in the leucine or methionine solution. The mass spectra obtained by analyzing the cotton balls exhibit singly and doubly ionized carbon ions of SWCNT and the characteristic fragments of the molecules, CH₃, CHCH₃, C₄H₇, CHNH₂ and COOH for leucine and CH₃, SCH₃, C₂H₄, C₄H₇, CHNH₂ and COOH for methionine.     

Quantitative structure-activity studies of octopaminergic agonists and antagonists against Locusta migratoria using similarity indexes

The quantitative structure-activity relationship of 39 octopamine (OA) agonists and 12 antagonists against the thoracic nerve cord of the migratory locust, Locusta migratoria L. was analyzed using atom based rigid fit method or flexible fitting offered by PowerFit 1.0 from MicroSimulation. For OA agonists, the more similar to reference compound NC (24) the structure of test compound, the higher the activity, whereas for OA antagonists it was not the case. Antagonists may not interact with the same part of the membrane with which the agonists interact. Taken the part of the membrane with which the agonist interacts as the true receptor, the antagonist may well interact with an area surrounding the receptor including the ionophore.     

Fällung nichtionogener Tenside durch Polymersäuren. Zusatzeffekt anorganischer Salze und Säure

Zusammenfassung Zusatz von Säure oder anorganischen Salzen, insbesondere von mehrwertigen Kationen, bewirkt die Fällung nichtionogener Tenside vom Typus des Polyoxyäthylens aus Wasser in Gegenwart von Polymersäuren wie Polyakrylsäure und Polymethakrylsäure, und zwar der Wirkung nach zunehmend mit der Temperatur. Die nichtionogenen Tenside bilden wasserlösliche Komplexe mit diesen Polymersäuren, und die Kationen und H⁺ veranlassen Kontraktion der Komplexe und führensomit zu ihrer Fällung. Die Rolle der Gegenionen (Anionen) ist bei hohen Salzkonzentrationen nicht zu vernachlässigen. Der Komplex von Polymersäure und nichtionogenen Tensiden mit län geren Polyoxyäthylenketten ist auf die Fällung hin sichtlich ihrer Zusätze weniger von Einfluß.

---

Summary Addition of acid or inorganic salts, particularly of polyvalent cations, causes precipitation of nonionic surfactants of the polyoxyethylene type from water in the presence of polymeric acids, such as polyacrylic and polymethacrylic acids. The precipitation takes place more remarkably at higher temperature. The non-ionics form water-soluble complexes with these polymeric acids, and the cations and H+ give rise to contraction of the complexes, thus leading them to precipitation. The counterions (anions) also play some part in the precipitation reaction at high salt concentrations. The complex of polymeric acid and nonionics with longer polyoxyethylene chains is less affected by these additives on precipitation.

---

---

Mit 9 Abbildungen     

ac ionic conductivity of hollandite type compounds from 100 Hz to 37.0 GHz

The frequency- and temperature-dependences of a.c. ionic conductivity of one-dimensional super-ionic conductors K-priderites with a hollandite type structures were investigated from 100 Hz to 37.0 GHz. Four kinds of K-priderite, K_1.6Mg_0.8Ti_7.2O₁₆, (K_1.3, Li_0.1) Mg_0.7Ti_7.3O₁₆, K_1.6Al_1.6Ti_6.4O₁₆ and (K_1.3, Li_0.2) Al_1.5Ti_6.5O₁₆, were studied. An equivalent circuit to combine the data of the complex conductivity at low and high frequencies was proposed. The data of complex conductivity at low frequencies can be analyzed in terms of the moving box model proposed by Beyeler et al. The transport of K⁺ ions at low frequencies is characterized by the cooperative motion of the K⁺ ions with various mobilities and is accompanied with the polarization of the K⁺ ions in the channels. The ion transport across intrinsic barriers at or above microwave frequencies is characterized by the frequency-independent ionic conductivity and is interpreted by the configurational model proposed by Beyeler et al. The height of intrinsic barriers is related to the lattice constants of a crystal.     

PTX phase equilibrium study of new solid solution systems,Cd1−xMxS (M = Mg,Ca, Sr)

Pressure, temperature, and composition phase equilibrium diagrams of new solid solution systems of the Cd_1?xM_xS (M = Mg, Ca, Sr) type were investigated using the quenching method. The stable region for the rock-salt-type phase is widely extended toward the high-temperature/low-pressure region by substituting 10–20 mole% of Cd with Ca or Sr. Temperature and composition phase diagrams for each solid solution system were obtained at 2 GPa. The rock-salt-type phase stability is discussed in view of these phase relations.