Efficient algorithms to enumerate isomers and diamutamers with more than one type of substituent

In this paper we describe numeric as well as symbolic algorithms for the enumeration of substitutional isomers with an unlimited number of different achiral substituents. We consider three different scenarios: first, the enumeration of diamutamers with a given set of ligand types and ligand multiplicity, second, the enumeration of diamutamer libraries with a given ligand assortment pattern, and, third, the enumerations of libraries with diamutamers exhibiting a limited number of ligands.     

连续波锁模Pr3+:YLF激光器

本文报导了采用氩离子激光器来泵浦Pr³⁺:YLF晶体,应用声光调制器实现了主动锁模;同时应用振动─高反射平面镜也实现了被动锁模,两种锁模均得到了ps光脉冲.据作者了解这是这种晶体材料的第一次锁模运转.     

Electrical properties of NbO in high magnetic fields

The resistivity and Hall coefficients of polycrystalline samples, single crystals, and doped specimens of NbO_x (0.98 ? x ? 1.02) were measured in magnetic fields up to 160 kG at 4.2, 78, and 295 K. The material is found to be an excellent conductor. The results are interpreted in terms of a nearly free electron model in which holes and electrons contribute jointly to conduction processes. Orbital switching, magnetic breakdown effects, and perturbations arising from impurities are invoked to explain the observed magneto-resistance anomalies.