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51.
The acoustical insertion losses produced by a balcony-like structure in front of a window are examined experimentally. The results suggest that the balcony ceiling is the most appropriate location for the installation of artificial sound absorption for the purpose of improving the broadband insertion loss, while the side walls are found to be the second best. Results also indicate that the acoustic modes of the balcony opening and the balcony cavity resonance in a direction normal to the window could have a great impact on the one-third octave band insertion losses. The maximum broadband road traffic noise insertion loss achieved is about 7 dB. 相似文献
52.
A full ligand-field energy matrix diagonalization treatment for 3d 1 ions in tetragonal symmetry is developed on the basis of the two spin?Corbit coupling parameter model, and the contributions of the spin?Corbit coupling of the ligand ions to the optical and electron paramagnetic resonance spectra are included. Spin Hamiltonian parameters of the tetragonal ${\rm V}^{4+}$ center in $\hbox{K}_2\hbox{SO}_4 {-} \hbox{Na}_2\hbox{SO}_4{-}\hbox{ZnSO}_4$ glass are calculated from the complete energy matrix diagonalization and the perturbation theory methods. The results calculated by both methods are not only close to each other but also in good agreement with the experimental values. Furthermore, the compressed defect structure of the ${\rm (VO_6)^{8-}}$ cluster is discussed. 相似文献
53.
David W. K. Yeung 《Annals of Operations Research》2014,220(1):181-204
Adoption of environment-preserving production technique plays a key role to effectively solving the continual worsening global industrial pollution problem. Due to the global nature of environmental effects and trade, unilateral response on the part of one nation is often ineffective. Cooperation in environmental management holds out the best promise of effective action. For cooperation over time to be credible, a dynamic consistency condition which requires the agreed-upon optimality principle to remain in effect throughout the collaboration duration has to hold. In this paper, we present a cooperative dynamic game of collaborative environmental management with production technique choices. A dynamically consistent cooperative scheme is derived. It is the first time that dynamically consistent solution is obtained for dynamic games in collaborative environmental management with production technique choices. The analysis widens the scope of study in global environmental management. 相似文献
54.
Hai-Yang Cheng C. Y. Cheung Wai Bong Yeung 《Zeitschrift fur Physik C Particles and Fields》1989,43(3):391-400
Using the recently proposed higher-order chiral Lagrangians determined from the integration of nontopological chiral anomalies, we calculate corrections to the current-algebra analysis ofK→3Π decay amplitudes expanded in powers of the Dalitz variables. Effects of quartic-derivative weak chiral Lagrangians are determined through the use of short-distance effective weak Hamiltonian and the factorization method. We find that (1) the constant and linear terms in the amplitude for ΔI=1/2K→3Π are in excellent agreement with experiment; the previous discrepancy of (20–35)% between current algebra and data is thus accounted for by the higher-order effective Lagrangians, (2) the penguin interaction does not play an essential role in the ΔI=1/2 rule, for otherwise it will lead to a large disagreement for the constant and linear terms, (3) one of the two quadratic terms in the ΔI=1/2 process, which arise from the quartic chiral Lagrangians, is in accord with data within experimental errors, while the other is off by four standard deviations, (4) the linear term in the ΔI=3/2 transitions is in good agreement with experiment and contributions from quadratic terms are sizable. 相似文献
55.
An improved synthesis of chiral diols via the asymmetric catalytic hydrogenation of prochiral diones
The rates of the asymmetric hydrogenation of prochiral diketones catalyzed by Ru(BINAP) catalysts were substantially accelerated in the presence of small amounts of a strong acid. 相似文献
56.
The real-time digestion of entrapped single-DNA molecules by λ-exonuclease in nanoporous alumina membranes was observed using an epifluorescence microscope. The alumina membrane provides pL (∼10−12 L) containers for confining single-DNA molecules without immobilization. When one end of the DNA molecule was inserted into a nanopore, it was possible to monitor the digestion process outside, near and inside the pore, where the individual DNA molecules exhibited different characteristic digestion modes. The digestion rates calculated from the decrease in fluorescence intensity showed different values according to the location of the individual molecules. Entrapment rather than immobilization allows the DNA strand to be fully exposed to the enzyme and the reaction buffer. These results confirm that the enzymatic digestion of DNA molecules is affected by their three-dimensional (3D) environment. 相似文献
57.
An efficient palladium-catalyzed cyanation of aryl chlorides is established. In the presence of a highly effective Pd/CM-phos catalyst, cyanation of aryl chlorides proceeds at 70 °C in general, which is the mildest reaction temperature achieved so far for this process. Common functional groups such as keto, aldehyde, ester, nitrile and -NH(2), and heterocyclic coupling partners including N-H indoles are well tolerated. Moreover, a sterically hindered nonactivated ortho,ortho-disubstituted electrophile is shown to be a feasible coupling partner in cyanation. 相似文献
58.
He H Lo PC Yeung SL Fong WP Ng DK 《Chemical communications (Cambridge, England)》2011,47(16):4748-4750
A series of unsymmetrical distyryl BODIPYs have been prepared which function as highly potent photosensitisers with in vitro IC(50) values as low as 15 nM. Their cellular uptake, subcellular localisation and photocytotoxicity depend greatly on the styryl substituents. 相似文献
59.
60.
Wai‐Yeung Wong Suk‐Yue Poon Jian‐Xin Shi Kok‐Wai Cheah 《Journal of polymer science. Part A, Polymer chemistry》2006,44(16):4804-4824
A series of blue‐light‐emitting oligo(fluorenyleneethynylenesilylene)s (OFESs) of the general formula HC?CRC?C(EC?CRC?C)mEC?CRC?CH (E = SiPh2, SiMe2, or SiMe2? SiMe2; m = 0–2; R = 9,9‐dihexylfluorene‐2,7‐diyl) and their phosphorescent platinum‐containing oligoynes and polyynes were synthesized and characterized. The solution properties and regiochemical structures of this new structural class of organosilicon‐based polyplatinayne polymers {trans‐[? Pt(PBu3)2C ?CRC?C(EC?CRC?C)mEC?CRC?C? ]n} were studied with IR and NMR (1H, 13C, 29Si, and 31P) spectroscopy. The optical absorption and photoluminescence spectra of these metallopolymers were examined and compared with their discrete oligomeric model complexes. Our studies led to a novel approach of using the sp3‐silyl moiety as a conjugation interrupter to limit the effective conjugation length in metal polyynes, which could boost the phosphorescence decay rates essential for light‐energy harvesting from the triplet excited state. The influence of the heavy platinum atom and the group 14 silyl unit possessing different side‐group substituents on the thermal and phosphorescence properties was investigated in detail. We also established the goal of studying the evolution of the lowest singlet and triplet excited states with chain length m of OFESs and the nature of E in these metallopolymers. This work indicated that the phosphorescence emission efficiency harnessed through the heavy‐atom effect of platinum in the main chain did not change very much with oligomer chain length m but generally decreased with the E group in the order SiMe2 > SiMe2? SiMe2 > SiPh2. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4804–4824, 2006 相似文献