The magnetic field-induced changes in the conductivity of metals are the subject of intense interest, both for revealing new phenomena and as a valuable tool for determining their Fermi surface. Here we report a hitherto unobserved magnetoresistive effect in ultra-clean layered metals, namely a negative longitudinal magnetoresistance that is capable of overcoming their very pronounced orbital one. This effect is correlated with the interlayer coupling disappearing for fields applied along the so-called Yamaji angles where the interlayer coupling vanishes. Therefore, it is intrinsically associated with the Fermi points in the field-induced quasi-one-dimensional electronic dispersion, implying that it results from the axial anomaly among these Fermi points. In its original formulation, the anomaly is predicted to violate separate number conservation laws for left- and right-handed chiral (for example, Weyl) fermions. Its observation in PdCoO2, PtCoO2 and Sr2RuO4 suggests that the anomaly affects the transport of clean conductors, in particular near the quantum limit.

The purpose of this study was to evaluate dentin bond strengths and to observe the adhesive-dentin interface after acid-base challenge using fluoride-free and fluoride-releasing self-etching adhesive systems; Clearfil SE Bond (SE), FL-Bond (FL) and FL-Bond II(FL II). Fifteen dentin surfaces from human molars were ground and bonded with one of three adhesive systems. The microtensile bond strength (µTBS) test was performed at a crosshead speed of 1 mm/min. The interface of the bonded specimens after acid-base challenge were also examined by a SEM.The µTBS of SE were significantly higher than those of FL and FL II (p<0.05), however, there were no significant differences between FL and FL II (p>0.05). An acid-base resistant zone (ABRZ) was observed in all the groups, however, formation of the ABRZ was material dependent. Fluoride-release from the adhesive is a key factor to create thick ABRZ.

Dentin bonding systems have been dramatically simplified and improved during the recent decades. Monomer penetration into dentin and its polymerization in situ creates a hybrid layer, which is essential to obtain good bonding to dentin. Moreover, the presence of an acid-base resistant zone below the hybrid layer has been documented with self-etching adhesive systems in an artificial secondary caries attack. When ultrastructure of the acid-base resistant zone is assessed by SEM and TEM observations, formation of the acid-base resistant zone is considered to be due to the monomer penetration potential and fluoride release in the adhesive systems. Natural dentin has a limited potential to resist an acid attack of secondary caries; however, the acid-base resistant zone does not purely consist of dentin in morphology, it is rather a combination of dentin and the adjacent hybrid layer. Therefore, the reinforced dentin has been called ''Super Dentin'' bearing the ability to prevent primary and secondary caries. Prospectively, the great potential of adhesive technology in creation of the ''Super Dentin'' would lead to the development of new materials for mechanical, chemical and biological protection of the dental structures. #

Resistance and magnetic torque measurements are reported in a layered organic superconductor, β"-(BEDT-TTF)4[(H3O)Ga(C2O4)3]C6H5NO2 with Tc=4.8 K, where BEDT-TTF stands for bis(ethylenedithio)tetrathiafulvalene. Because of the large anion between the BEDT-TTF conducting layers, the superconductivity of this salt is highly anisotropic. In magnetic fields parallel to the conducting layers for T = 0.4 K, the magnetic torque shows a large diamagnetic signal associated with hysteresis up to ∼21 T, suggesting the upper critical field Hc2 > ∼ 21 T at 0.4 K. The large reduction of the diamagnetic signal is observed above 16 T, which shows a Fulde and Ferrell, and Larkin and Ovchinnikov (FFLO) phase transition. For T = 0.5 K, the interlayer resistance has non-zero value in a wide field region up to Hc2, arising from the Josephson vortex dynamics. Successive dips in the second derivative curves of the resistance are observed between 16 T and Hc2, which are ascribed to the commensurability effect between the Josephson vortex lattice and the order parameter oscillation of the FFLO phase. The commensurability effect is observed only in nearly parallel fields, showing that the FFLO phase is stable in a very limited field angle region. The temperature-field phase diagram is determined.