Identification of characteristic protein folding channels in a coarse-grained hydrophobic-polar peptide model

Folding channels and free-energy landscapes of hydrophobic-polar heteropolymers are discussed on the basis of a minimalistic off-lattice coarse-grained model. We investigate how rearrangements of hydrophobic and polar monomers in a heteropolymer sequence lead to completely different folding behaviors. Studying three exemplified sequences with the same content of hydrophobic and polar residues, we can reproduce within this simple model two-state folding, folding through intermediates, as well as metastability.     

Simple Twisted Group Algebras of Dimension p4 and their Semi-Centers

For a simple twisted group algebra over a group G, if G^∣ is Hall subgroup of G, then the semi-center is simple. Simple twisted group algebras correspond to groups of central type. We classify all groups of central type of order p⁴ where p is prime and use this to show that for odd primes p there exists a unique group G of order p⁴, such that there exists simple twisted group algebra over G with a commutative semi-center. Moreover, if 1 < |G| <64, then the semi-center of simple twisted group algebras over G is noncommutative and this bounds are strict.     

Entanglement of macroscopic test masses and the standard quantum limit in laser interferometry

We show that the generation of entanglement of two heavily macroscopic mirrors is feasible with state of the art techniques of high-precision laser interferometry. The basis of such a demonstration would be a Michelson interferometer with suspended mirrors and simultaneous homodyne detections at both interferometer output ports. We present the connection between the generation of entanglement and the standard quantum limit (SQL) for a free mass. The SQL is a well-known reference limit in operating interferometers for gravitational-wave detection and provides a measure of when macroscopic entanglement can be observed in the presence of realistic decoherence processes.     

Neue ternäre Arsenide des Caesiums mit Elementen der 8. Nebengruppe

New Ternary Arsenides of Cesium with 8b-Elements Cs₂PdAs₂ was prepared from the elements. It is isotypic with K₂PdAs₂ (A₂MX₂) and crystallizes orthorhombically, space group Cmcm, with the following constants: a = 706.8(4) pm; b = 1476.6(7) pm; c = 636.6(3) pm. The structure is characterized by MX₂-zigzag-ribbons surrounded by channel-like arranged alkali atoms. The new ternary compounds CsRu₂As₂ and CsRh₂As₂ are isotypic with ThCr₂Si₂ (inferred from powder photographs).     

Untersuchung der magnetischen Protonenresonanz von Kristallhydraten der Carnallit-Reihe

PMR Investigation on crystalline Carnallite Hydrates Using a wide-line spectrometer it was investigated the proton magnetic resonance of polycristalline compounds of the type MeCI · MgCI₂ · 6 H₂O with Me = K, Rb, Cs, NH₄ (carnallites) and of two extremely similar polycristalline compounds of the type Me′CI · MgCl₂·7 H₂ with vie′ = H, Li. These materials exhibit a stepwise decrease of the second moment of their proton resonance signal at increasing temperature, down to a final value which is about a quarter of the low temperature value of the second moment. This behaviour has to be interpreted to be the consequence of the transition of all water molecules into a state of rapid rotation around a fixed axis. It has to be concluded from details of the behaviour of the two heptahydrates, that they are of the type of Carnallite too (hexahydrates), one water molecule of the respective formula unit belonging to the cation (H₃O- resp. LiH₂O-carnallite).     

Zum selektiven NMR-Spinecho-Verhalten bei Systemen mit I = 1 im Festkörper am Beispiel des Kaliumoxalatmonohydrats

Investigation of the Selective N.M.R. Spin Echo Response of I = 1 Systems in Solids Demonstrated on Potassium Oxalate Monohydrate The theory of the nonselective spin echo response in solids for dipolar-coupled spins I = 1 with quadrupole interaction by BODEN et al. [5] is modified for the case of selective irradiation to only one line of the n.m.r. spectrum. The theoretical results are compared with ¹H-n.m.r. experiments on dipolar-coupled protonpairs of a (KCOO)₂ · H₂O single crystal. This is possible because in this material the interpair dipolar interaction is substantially smaller than the intrapair dipolar interaction. An echo response results which has some similarities to the behaviour of spin systems with heteronuclear coupling.     

Laser flash photolysis studies on excited singlet states of benzene,toluene, p-xylene,polystyrene, and poly-α-methylstyrene

Optical absorption spectra obtained in cyclohexane solutions of benzene, toluene, and p-xylene contain bands at 620 to 640 nm, assigned to S_n← S₁ monomer transitions. With concentrated solutions, excimer absorption spectra nave been found. With the two polymers, absorption of (intramolecular) excimers has been detected only.