410 research outputs found
Frequency-Rank Correlations of Rhodopsin Mutations with Tuned Hydropathic Roughness Based on Self-Organized Criticality
The behavior of disease-linked mutations of membrane proteins is especially
simple in rhodopsin, where they are well-studied, as they are responsible for
retinitis pigmentosa, RP (retinal degeneration). Here we show that the
frequency of occurrence of single RP mutations is strongly influenced by their
posttranslational survival rates, and that this survival correlates well (82%)
with a long-range, non-local hydropathic measure of the roughness of the water
interfaces of ex-membrane rhodopsin based on self-organized criticality (SOC).
It is speculated that this concept may be generally useful in studying survival
rates of many mutated proteins
Polarized inclusive leptoproduction, , and the hadron helicity density matrix, : possible measurements and predictions
We discuss the production of hadrons in polarized lepton nucleon interactions
and in the current jet fragmentation region; using the QCD hard scattering
formalism we compute the helicity density matrix of the hadron and show how its
elements, when measurable, can give information on the spin structure of the
nucleon and the spin dependence of the quark fragmentation process. The cases
of vector mesons and baryons are considered in more details
and, within simplifying assumptions, some estimates are given.Comment: 17 pages + 4 figures, plain LATeX, figures appended as uuencoded,
compressed postscript fil
Ethyl 2-[(carbamothioylamino)imino]propanoate
The title compound, C6H11N3O2S, consists of a roughly planar molecule (r.m.s deviation from planarity = 0.077 Å for the non-H atoms) and has the S atom in an anti position to the imine N atom. This N atom is the acceptor of a strongly bent internal N—H⋯N hydrogen bond donated by the amino group. In the crystal, molecules are arranged in undulating layers parallel to (010). The molecules are linked via intermolecular amino–carboxyl N—H⋯O hydrogen bonds, forming chains parallel to [001]. The chains are cross-linked by Ncarbazone—H⋯S and C—H⋯S interactions, forming infinite sheets
Mixed metal node effect in zeolitic imidazolate frameworks
We synthesized two series of bimetallic (zinc and cobalt) zeolitic imidazolate frameworks (ZIF-62) under different solvothermal conditions. It is found that the structure of the derived ZIF crystals is highly sensitive to synthesis conditions. One series possesses the standard ZIF-62 structure, whereas the other has a mixed structure composed of both the standard structure and an unknown one. The standard series exhibits a slight negative deviation from linearity of melting temperature (T(m)) and glass transition temperature (T(g)) with the substitution of Co for Zn. In contrast, the new series displays a stronger negative deviation. These negative deviations from linearity indicate the mixed metal node effect in bimetallic ZIF-62 due to the structural mismatch between Co(2+) and Zn(2+) and to the difference in their electronic configurations. The new series involves both cobalt-rich and zinc-rich phases, whereas the standard one shows one homogeneous phase. Density functional theory calculations predict that the substitution of Co for Zn increases the bulk modulus of the ZIF crystals. This work indicates that the structure, melting behaviour, and mechanical properties of ZIFs can be tuned by metal node substitution and by varying the synthetic conditions. Both series of ZIFs have higher glass forming abilities due to their higher T(g)/T(m) ratios (0.77–0.84) compared to most good glass formers
Single spin asymmetries in QCD
Measurements of single transverse spin asymmetries in high energy inclusive
processes have always shown unexpected and challenging results. Several cases
are considered and discussed within a QCD approach which couples perturbative
dynamics to new non perturbative partonic information; the aim is that of
developing a consistent phenomenological description of these unusual single
spin phenomena, based on a generalized QCD factorization scheme.Comment: 14 pages, lectures delivered at School on "Symmetries and Spin",
Praha-SPIN-2001, Prague, July 15 - July 28, 200
- …