Rare decay modes of the K-mesons in the chiral lagrangian

The decays K_S → γγ, K_L → γγ and K_L → μ⁺μ⁻ are studied within the framework of chiral lagrangians. The one loop contribution to K_S → γγ turns out to be finite, giving an unambiguous prediction. The results also indicate that the long-distance dispersive part of K_L → μ⁺μ⁻ is the dominant one. As for K_L → γγ, a possible difficulty is pointed out with the recently published value ϑ ⋍ 20° for the η − η′ mixing angle.     

Quantitative XPS — multiline approach

The algorithm for quantitative XPS analysis developed some years ago has been extended by a new presentation of the fundamental parameters and by using as many lines as possible from each element under investigation. It now gives the opportunity to reduce the influences of statistical (from measurement) and systematic errors (from fundamental parameters) on quantitative analysis results.     

Isomorphism in quasiperiodic structures

Quasicrystalline alloys of the Al-T systems (with T a 3d transition metal or alloy) have been prepared by rapid quenching from the melt and neutron diffraction patterns have been measured. Isomorphicities in the structure have been observed for alloys with T within the composition ranges of α-Mn solid solution or of σ-phases.     

General results on glueball masses in QCD

A number of authors have investigated mass inequalities for mesons and baryons in QCD. These provide rigorous non-perturbative constraints on the mass spectrum. Similar inequalities for glueballs are investigated. For nonzero spin J, in the large-N_c approximation, m_J⁻⩾m_J⁺ is found. (For J = 0, the existence of a gluon condensate can modify this statement.) There are also constraints on how fast m_J can grow with J. For example, for m_J = a + bJ^α, 0 ⩽ α ⩽ 1 is found, a result consistent with Regge behaviour.     

Adaptive coordination assemblies based on a flexible tetraazacyclododecane ligand for promoting carbon dioxide fixation

Coordination hosts based on flexible ligands have received increasing attention due to their inherent adaptive cavities that often show induced-fit guest binding and catalysis like enzymes. Herein, we report the controlled self-assembly of a series of homo/heterometallic coordination hosts (Me₄enPd)_2n(ML)_n [n = 2/3; M = Zn(ii)/Co(ii)/Ni(ii)/Cu(ii)/Pd(ii)/Ag(i); Me₄en: N,N,N′,N′-tetramethylethylenediamine] with different shapes (tube/cage) from a flexible tetraazacyclododecane-based pyridinyl ligand (L) and cis-blocking Me₄enPd(ii) units. While the Ag(i)-metalated ligand (AgL) gave rise to the formation of a (Me₄enPd)₄(ML)₂-type cage, all other M(ii) ions led to isostructural (Me₄enPd)₆(ML)₃-type tubular complexes. Structural transformations between cages and tubes could be realized through transmetalation of the ligand. The buffering effect on the ML panels endows the coordination tubes with remarkable acid–base resistance, which makes the (Me₄enPd)₆(ZnL)₃ host an effective catalyst for the CO₂ to CO₃²⁻ conversion. Control experiments suggested that the integration of multiple active Zn(ii) sites on the tubular host and the perfect geometry match between CO₃²⁻ and the cavity synergistically promoted such a conversion. Our results provide an important strategy for the design of adaptive coordination hosts to achieve efficient carbon fixation.

A series of coordination hosts were prepared and their applications in CO₂ fixation were studied.     

Modified constructions of binary sequences using multiplicative inverse

Two new families of finite binary sequences are constructed using multiplicative inverse. The sequences are shown to have strong pseudorandom properties by using some estimates of certain exponential sums over finite fields. The constructions can be implemented fast since multiplicative inverse over finite fields can be computed in polynomial time.     

Dynamic Behavior of Lambda-Type Three-Level Atoms and Two-Mode Cavity Field

A system comprising of Lambda-type three-level atoms and the two-mode cavity field is considered in this paper. Under the adiabatical approximation and the large detuning condition, the effective Hamiltonian of the system in the interaction picture can be given out. If the two identical three-level atoms pass through the cavity in turn, the entangled state atoms can be generated. When the interaction time is taken to an appropriate value, the maximally entangled states are created. At the same time, the dynamic behaviors of the system are studied in detail.     

Critical behaviour of elastically coupled systems with spatially anisotropic critical fluctuations

The spatial anisotropy of critical fluctuations has strong influence on the temperature dependence of the elastic constants of an elastic medium coupled magneto- or electrostrictive to the order parameter. Under pinned boundary conditions we find for uniaxial dipolar systems of hexagonal and trigonal symmetry a second order phase transition, where only c₁₁ and c₁₂ show critical behaviour. For other symmetries a first order transition is expected. At an uniaxial Lifshitz point only c₃₃ becomes critical and the phase transition remains of second order for any symmetry.     

Electrical resistivity in intermetallic equiatomic RPt compounds with R  La,Pr, Nd,Gd, Tb,Dy, Ho and Er

We present the electrical resistivity measurements of equiatomic RPt compounds, with R  La, Pr, Nd, Gd, Tb, Dy, Ho and Er, which crystallize into two different orthorhombic structures. The different contributions to the total resistivity were separated. From the phonon contribution ϱ_p we estimated the Debye temperature θ_D of the different compounds. Except for GdPt, the increase of the magnetic resistivity above T_c arise from crystal field effects which are larger than those calculated in the point charge model. The paramagnetic Curie temperature and the saturated magnetic resistivity follow approximately the de Gennes law and allowed us to estimate effective mass and the exchange constant through the series.