Search for rare and forbidden eta(') decays

We have searched for rare and forbidden decays of the eta(') meson in hadronic events at the CLEO II detector. The search is conducted on 4.80 fb(-1) of e(+)e(-) collisions at 10.6 GeV center-of-mass energy at the Cornell Electron Storage Ring. We find no signals, and set 90% confidence level upper limits of their branching fractions: B(eta(')-->e(+)e(-)eta)<2.4x10(-3), B(eta(')-->e(+)e(-)pi(0))<1. 4x10(-3), B(eta(')-->e(+)e(-)gamma)<0.9x10(-3), and B(eta(')-->e&mgr;)<4.7x10(-4). We also fit the matrix element of the eta(')-->pi(+)pi(-)eta Dalitz plot with the parametrization |M|(2) = A|1+alphay|(2), where y is a linear function of the kinetic energy of the eta, and find Re (alpha) = -0.021+/-0.025.     

Experimental validation of the differential image motion lidar concept

We have experimentally validated the concept of a differential image motion (DIM) lidar for measuring vertical profiles of the refractive-index structure characteristic C(n)(2) by building a hard-target analog of the DIM lidar and testing it against a conventional scintillometer on a 300-m horizontal path throughout a range of turbulent conditions. The test results supported the concept and confirmed that structure characteristic C(n)(2) can be accurately measured with this method.     

Angle-resonant stimulated polariton amplifier

We experimentally demonstrate resonant coupling between photons and excitons in microcavities which can efficiently generate enormous single-pass optical gains approaching 100. This new parametric phenomenon appears as a sharp angular resonance of the incoming pump beam, at which the moving excitonic polaritons undergo very large changes in momentum. Ultrafast stimulated scattering is clearly identified from the exponential dependence on pump intensity. This device utilizes boson amplification induced by stimulated energy relaxation.     

零排放燃气轮机的空气动力学特性

本文对采用二氧化碳作为基本工作流体的半闭环燃气轮机循环的空气动力学特性进行了详尽的分析.结果表明,不同工作流体的比热比值对压气机的压比、等熵效率及临界堵塞质量流量影响很大,并详细阐述了一种比热比对透平机械性能影响的修正方法,进而提出了一种零排放发动机的设计新思路,揭示了最初为空气工质而设计的压气机可以直接用于CO2零排放发动机中.     

Polystyrene/decahydronaphthalene/propane phase equilibria and polymer conformation properties from intrinsic viscosities

The influence of dissolved propane (up to 31.2 wt %) on the phase equilibria of 5 wt % polystyrene (PS) dissolved in 66/34 wt % trans/cis‐decahydronaphthalene (DHN) was measured over the temperature range of 323–423 K. A suitable temperature, pressure, and propane composition operating space was defined to measure intrinsic viscosities of a single fluid phase. Intrinsic viscosities of PS in cosolvent mixtures of propane and trans/cis‐DHN were measured between 323 and 423 K and between 70 and 208 bar. The addition of propane to the isomeric mixture of DHN resulted in a decreased solvent quality for PS, causing a contraction of the PS coil. The most dramatic decrease in solvent quality with the addition of propane occurred at 323 K and 70 bar with approximately a 36% reduction in the viscometric radius with the addition of 45 mol % propane to DHN. At 423 K, the solvent quality was less sensitive to the addition of propane and only a 13% reduction in the viscometric radius was observed at 70 bar and 45 mol % propane in DHN. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Concise,efficient and highly selective asymmetric synthesis of (+)-(3S,4R)-cisapride

A concise asymmetric synthesis of the gastroprokinetic agent (+)-(3S,4R)-cisapride {(+)-(3S,4R)-N(1)-[3′-(4″-fluorophenoxy)propyl]-3-methoxy-4-(2″′-methoxy-4″′-amino-5″′-chlorobenzamido)piperidine} from commercially available starting materials has been developed. The key step of this synthesis employs the diastereoselective conjugate addition of lithium (R)-N-benzyl-N-(α-methylbenzyl)amide to tert-butyl 5-[N-3′-(4″-fluorophenoxy)propyl-N-allylamino]pent-2-enoate and in situ enolate oxidation with (?)-camphorsulfonyloxaziridine to set the (3S,4R)-configuration found within the piperidine ring of the product. This synthesis proceeds in 9 steps from commercially available 1-(4′-fluorophenoxy)-3-bromopropane with an overall yield of 19%.