Z \to b\bar b in a composite model of fermions

A composite model of fermions is proposed to explain the “anomaly” in $Z \to b\bar b$ and, to a lesser extent, in $Z \to c\bar c$ It contains a nonsequential fourth family whose mass of one member (the charge ? 1/3 quark) is constrained to be between 47 GeV and 49 GeV. The charge + 2/3 quark is constrained to lie between 67 GeV and 107 GeV. This opens up the exciting prospect for nearfuture discoveries at LEP2 and possibly at the Tevatron.     

Synthesis and X-ray structure of p-tolyl phenylthioglyoxylate

The title compound (C₁₅H₁₂O₂S) is triclinic witha=7.077(10),b=8.825(2),c=11.068(2) Å, =106.66(3)^o, Z=2, and space group P. The significant structural features lies in the two carbonyl groups of the thioglyoxylate which are oriented antiperiplanar to each other [–168.2(2)^o]. The central C(8)–C(9) bond is 1.553(3) Å. The phenyl rings are twisted with respect to the carbonyl groups. Short contacts are present between S and O(1) [2.652(2) Å] and also between S and O(2) [2.758(2) Å].     

Chemical constituents from the leaves of Manglietia phuthoensis and their effects on osteoblastic MC3T3-E1 cells

Two new phenyl glycosides, mangliesides A and B (1, 2), a new ionol glycoside, manglieside C (3), two new lignan glycosides, mangliesides D and E (4, 5), were isolated from the leaves of Manglietia phuthoensis, along with two known lignans, 3-methoxymagnolol (6) and obovatol (7). Their structures were established by means of 1D and 2D NMR, electrospray ionization (ESI)-MS and HR-ESI-MS experiments. Among them, compounds 2 and 5 significantly (p<0.05) increased the growth and differentiation of osteoblastic MC3T3-E1 cells in vitro.     

A Frustrated and Confused Lewis Pair

We report a new class of frustrated Lewis pairs (FLPs) by the hydroboration of bulky isocyanates ^iPr2ArNCO (^iPr2Ar=2,6‐iPr₂C₆H₃) and ^Ph2tBuArNCO (^Ph2tBuAr=2,6‐Ph₂‐4‐tBuC₆H₂) with Piers’ borane (HB(C₆F₅)₂). While hydroboration of smaller isocyanates such as ^iPr2ArNCO leads to isocyanate—N/B FLP adducts, hydroboration of the bulkier ^Ph2tBuArNCO allows isolation of the substrate‐free aminoborane with a short, covalent N?B bond. This confused FLP reversibly binds unsaturated substrates such as isocyanates and isocyanides, suggesting the intermediacy of a “normal” FLP along the reaction pathway, supported by high‐level DFT studies and variable‐temperature NMR spectroscopy. These results underscore the possibility of FLP behavior in systems that possess no obvious frustrated Lewis acid–base interaction.     

Even and Odd Charge Coherent States: Higher-Order Nonclassical Properties and Generation Scheme

We examine the higher-order nonclassical properties of the even and odd charge coherent states as well as proposing a scheme to generate these states whose modes can freely travel in open space. We show that the even and odd charge coherent states exhibit both higher-order antibunching and higher-order squeezing. While the two-mode higher-order antibunching occurs in any order and essentially depends on the charge number, the two-mode higher-order squeezing appears only in the even orders. We also prove that these states are genuinely entangled, and they can be generated by means of cross-Kerr media, beam splitters, phase shifts and threshold detectors. We find that the fidelity and the corresponding success probability to generate these states are dependent on the correlative parameters.     

Dynamically consistent discrete metapopulation model

In this paper we construct nonstandard difference schemes, which are dynamically consistent with a metapopulation model formulated by Keymer et al. in 2000, i.e. preserve all dynamical properties of the differential equations of the model. These properties are: monotone convergence, boundedness, local asymptotic stability and especially, global stability of equilibria and non-periodicity of solutions. Numerical examples confirm the obtained theoretical results of the properties of the constructed difference schemes.     

Synthese und Struktur von Mo2NCl7

Synthesis and Structure of Mo₂NCl₇ The reaction of VN with MoCl₅ at 175 °C in a sealed glass ampoule yields the molybdenum(V) nitride chloride Mo₂NCl₇ in form of air sensitive black crystals with the triclinic space group P1¯ and a = 905.7(8); b = 975.4((6); c = 1283.4(8) pm, α = 103.13(4)°; β = 109.83(5)° und γ = 98.58(5)°. The crystal structure is built up from dinuclear units [Mo₂N₂Cl₇]^3— and [Mo₂Cl₇]³⁺, which are connected by asymmetric nitrido bridges to form endless chains. Within both dinuclear units the Mo atoms are bridged by three Cl atoms resulting in a Mo‐Mo distance of 349.2(3) pm in the unit [Mo₂N₂Cl₇]^3—. In case of [Mo₂Cl₇]³⁺, however, a shorter Mo‐Mo distance of 289.4(3) pm is observed, which can be interpreted by a single bond. Correspondingly a reduced magnetic moment of 0.95 B.M. per Mo atom is observed.     

Size- and shape-dependent effective conductivity of porous media with spheroidal gas-filled inclusions

Porous media containing gas-filled inclusions embedded in a solid phase constitute an important class of natural or artificial materials of both theoretical and practical interest. In these materials, thermal conductivity is one of the most important properties. In a variety of situations of practical interest, when the characteristic size of gas-filled inclusions is comparable with the mean free path of gas molecules and when the slip flow regime is considered, the behavior of gas near solid surfaces cannot be described by classical thermal conductivity equations. In fact, the boundary conditions at the solid surfaces must be modified by considering that the temperature and normal heat flux simultaneously suffer a discontinuity. The first purpose of the present work is to develop an efficient and accurate micromechanical model capable of estimating the effective conductivity of porous materials while taking into account the discontinuities of the temperature and normal heat flux across solid surfaces and the non-spherical form of gas-filled inclusions. The second purpose of the present work is to study the dependencies of the effective conductivity on the size and shape of gas-filled inclusions. By applying the micromechanical model based on the differential scheme and by using the solution results obtained for auxiliary dilute problem accounting for modified boundary conditions on surface solids, the closed-form expression for the effective conductivity is obtained. Numerical results are provided to illustrate the dependence of the effective conductivity on the size and shape of gas-filled inclusions in the case of randomly oriented inclusions.     

Growth of carbon nanotubes on stainless steel substrates by DC-PECVD

We report on the fabrication of carbon nanotubes (CNTs) on Ni-coated stainless steel (SUS) substrates by using dc plasma enhanced chemical vapor deposition. The synthesized CNTs have the diameter of about 30 nm and the length of about 1.2 μm. To verify the effects of SUS substrates on the growth of CNTs, CNTs had also been grown on Ni-coated Si substrates. CNTs grown on the SUS substrates were more uniform compared with those grown on the Si substrates. Field emission properties of the CNT films were measured in the diode configuration, and the turn-on electric field of 3.87 V/μm and field enhancement factor β of about 1737 were obtained from the synthesized CNTs at the gap of 500 μm between the SUS substrate and the anode. These results have not only clarified the effects of the substrate on the growth of CNTs, but also shown the potential of CNTs in field emission applications, especially CNT-based cold-cathode X-ray tubes.