Columnar mesomorphism from hemi-disklike metallomesogens derived from 2,6-bis[3',4',5'-tri(alkoxy)phenyliminomethyl]pyridines (L): crystal and molecular structures of [M(L)Cl2] (M=Mn,Ni, Zn)

Four new series of non-disklike complexes of general formula [MCl(2)(L(n))] based upon substituted 2,6-bis(3',4',5'-trialkoxyphenyliminomethyl)pyridine ligands (L(n)) and with M=Zn(II), Co(II), Mn(II), and Ni(II) have been prepared and examined for liquid crystallinity. A complete analysis of the thermal behavior by polarized-light optical microscopy, differential scanning calorimetry, and small-angle Xray scattering revealed a rich and varied mesomorphism. Moreover, the high thermal stability of the compounds leads to rather extended mesomorphic ranges. The nature and thermal stability of each mesophase depend on both the length of the six terminal alkoxy chains, n (n=8, 10, 12, 14, 16), and on the metal ions. As demonstrated by small-angle Xray diffraction experiments, the mesomorphism of these complexes is solely of the columnar type. One compound shows an oblique columnar phase, while most of them show a hexagonal columnar phase, Col(h), and several types of rectangular columnar phase, Col(r). Xray single-crystal structures obtained for three methoxy derivatives confirm the 1:1 metal-ligand stoichiometry of the complexes, in which the metal is pentacoordinate with a distorted, trigonal bipyramidal geometry. The crystalline structures also reveal the existence of some columnar organization in the solid state, the columns resulting from an alternated stacking of the complexes in one direction. By combining these results with those obtained from dilatometry experiments, a model for the molecular organization within the mesophases is proposed in which an antiparallel arrangement of the metallomesogens is retained in the mesophase.     

Jaumann transport in relativistic continuum mechanics

We define the Jaumann derivative of a tensor field in relativity by a formal generalization of a stress rate in viscoelasticity. A tensor field is said to be Jaumann transported iff its Jaumann derivative vanishes. It is found that the gravitational potentials are Jaumann transported identically. The concept of a complete rotation tensor has been introduced to study the Jaumann derivative with respect to a null vector field. This provides a characterization of the integrability of a hypersurface orthogonal congruence. A perfect fluid collapsing by neutrino emission and undergoing Jaumann transport with respect to the neutrino flow is found to be compatible with that of a catastrophic collapse. The circumstances leading to the existence of ghost neutrinos are cited. The degeneracy of the Kerr-Newman black hole into the Reissner-Nordstrom black hole is expressed in terms of the Jaumann propagation.     

Measurement of the elasticity and ultrasound velocities of steel

This paper describes two pieces of equipment designed to provide data on the elastic moduli and ultrasound velocities of steel at both sub-zero and elevated temperatures. Typical results are given for various steels and the advantages and accuracies of each method are outlined. A possible use of ultrasound velocity as a practical indication of temperature is suggested.     

Neuroprotective effects of edaravone-administration on 6-OHDA-treated dopaminergic neurons

Background

A recent human clinical trial of an Alzheimer's disease (AD) vaccine using amyloid beta (Aβ) 1–42 plus QS-21 adjuvant produced some positive results, but was halted due to meningoencephalitis in some participants. The development of a vaccine with mutant Aβ peptides that avoids the use of an adjuvant may result in an effective and safer human vaccine.

Results

All peptides tested showed high antibody responses, were long-lasting, and demonstrated good memory response. Epitope mapping indicated that peptide mutation did not lead to epitope switching. Mutant peptides induced different inflammation responses as evidenced by cytokine profiles. Ig isotyping indicated that adjuvant-free vaccination with peptides drove an adequate Th2 response. All anti-sera from vaccinated mice cross-reacted with human Aβ in APP/PS1 transgenic mouse brain tissue.

Conclusion

Our study demonstrated that an adjuvant-free vaccine with different Aβ peptides can be an effective and safe vaccination approach against AD. This study represents the first report of adjuvant-free vaccines utilizing Aβ peptides carrying diverse mutations in the T-cell epitope. These largely positive results provide encouragement for the future of the development of human vaccinations for AD.     

The unprecedented reaction of dimethylsulfonium methylide with Michael acceptors: synthesis of 1-substituted vinyl silanes and styrenes

Rather than the usual cyclopropanation, conditions for an unprecedented elimination reaction from the adduct of dimethylsulfonium methylide and various Michael acceptors have been established leading to functionalized 1-substituted alkenes. In silyl substituted substrates (2a and 2h), where a facile Peterson-type olefination is possible from the adduct; elimination took place instead to give functionalized 1-substituted vinyl silanes. Aryl substituted Michael acceptors (2b-e, 2g and 2i-k) also underwent a similar kind of olefination to give 1-substituted styrene derivatives with moderate yields along with a side product, which arose by nucleophilic demethylation from the adduct of dimethylsulfonium methylide and arylidene malonates. Hammett studies revealed that selectivity for olefination vs. demethylation increases as the aryl substituent becomes more electron deficient. Alkylidene malonates (2f and 2l) with a beta-alkyl substituent did not favour the olefination process. Sequential addition of Michael acceptors and alkyl halides to a mixture of dimethylsulfonium methylide and sodium dimsylate provided olefination followed by alkylation on the active methine group. A mechanistic pathway has been formulated from the studies of a few sulfonium methylides.     

A novel reaction of dimethylsulfonium methylide with Michael acceptors: application to the synthesis of difficultly accessible vinyl silanes and styrenes

Rather than the usual cyclopropanation and Peterson-type olefination, conditions for a novel elimination reaction from the adduct of dimethylsulfonium methylide and 2-silylalkylidene/arylidene malonate/cyanoacetate/phosphonoacetate leading to geminally substituted vinyl silanes or styrenes, respectively, have been established.     

Laser Spectroscopy of the CCO Radical in the 0.77-μm Region: Analysis of theÃ(020)κΠ andÃΠi(001) States

TheÃ(020)κ³Π–X³Σ⁻(000) andóΠ_i(001)–X³Σ⁻(000) bands of the CCO radical have been investigated by laser spectroscopy with two types of tunable laser system. An analysis was made simultaneously for both the bands to establish line assignments and determine molecular constants for both theÃ(020) andÃ(001) states. A coupling constant between these two states was also determined by assuming the interaction to be of Fermi type.     

Crystal base andq-vertex operators

Theq-deformed vertex operators of Frenkel and Reshetikhin are studied in the framework of Kashiwara's crystal base theory. It is shown that the vertex operators preserve the crystal structure, and are naturally labeled by the global crystal base. As an application the one point functions are calculated for the associated elliptic RSOS models, following the scheme of Kang et al. developed for the trigonometric vertex models.Dedicated to Huzihiro Araki     

Magnetic properties of Mn3B4 under high magnetic field

The magnetic properties of antiferromagnetic compound Mn₃B₄ were examined using pulsed magnetic field up to 470 kOe. It was found that Mn₃B₄ shows a clear metamagnetic transition under 360 kOe at 4.2K. The present results are not explained by the magnetic structure proposed by Neov and a modified magnetic structure is proposed to understand the present magnetization curve. The magnetic phase diagram in the H-T plane is shown.     

Crystal and molecular structure of iso-grayanotoxin II

The crystal and molecular structure of a grayanotoxin derivative, iso-grayanotoxin II, is presented. The crystal is orthorhombic, space group . The molecule is based on a tetracyclic structure consisting of two five-membered, one six-membered, and one seven-membered rings with various conformations.