Yield Management: Editorial Introduction

“Yield Management, which involves the allocation of seats to different classes of customers (paying different prices) has produced significant improvements in load factors and revenues for airlines and represents a major success for OR”?Ormerod¹     

Abnormal solvent effects on hydrogen atom abstraction. 2. Resolution of the curcumin antioxidant controversy. The role of sequential proton loss electron transfer

The rates of reaction of 1,1-diphenyl-2-picrylhydrazyl (dpph*) radicals with curcumin (CU, 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione), dehydrozingerone (DHZ, "half-curcumin"), and isoeugenol (IE) have been measured in methanol and ethanol and in two non-hydroxylic solvents, dioxane and ethyl acetate, which have about the same hydrogen-bond-accepting abilities as the alcohols. The reactions of all three substrates are orders of magnitude faster in the alcohols, but these high rates can be suppressed to values essentially equal to those in the two non-hydroxylic solvents by the addition of acetic acid. The fast reactions in alcohols are attributed to the reaction of dpph* with the CU, DHZ, and IE anions (see J. Org. Chem. 2003, 68, 3433), a process which we herein name sequential proton loss electron transfer (SPLET). The most acidic group in CU is the central keto-enol moiety. Following CU's ionization to a monoanion, ET from the [-(O)CCHC(O)-](-) moiety to dpph* yields the neutral [-(O)CCHC(O)-]* radical moiety which will be strongly electron withdrawing. Consequently, a phenolic proton is quickly lost into the alcohol solvent. The phenoxide anion so formed undergoes charge migration to produce a neutral phenoxyl radical and the keto-enol anion, i.e., the same product as would be formed by a hydrogen atom transfer (HAT) from the phenolic group of the CU monoanion. The SPLET process cannot occur in a nonionizing solvent. The controversy as to whether the central keto-enol moiety or the peripheral phenolic hydroxyl groups of CU are involved in its radical trapping (antioxidant) activity is therefore resolved. In ionizing solvents, electron-deficient radicals will react with CU by a rapid SPLET process but in nonionizing solvents, or in the presence of acid, they will react by a slower HAT process involving one of the phenolic hydroxyl groups.     

Solvolysis of para-substituted cumyl chlorides. Brown and Okamoto's electrophilic substituent constants revisited using continuum solvent models

Brown and Okamoto (J. Am. Chem. Soc. 1958, 80, 4979) derived their electrophilic substitutent constants, sigma(p)+, from the relative rates of solvolysis of ring-substituted cumyl chlorides in an acetone/water solvent mixture. Application of the Hammett equation to the rates for the meta-substituted cumyl chlorides, where there could be no resonance interaction with the developing carbocation, gave a slope, rho(+) = -4.54 ( identical with 6.2 kcal/mol free energy). Rates for the para-substituted chlorides were then used to obtain sigma(p)+ values. We have calculated gas-phase C-Cl heterolytic bond dissociation enthalpy differences, Delta BDE(het) (= BDE(het)(4-YC(6)H(4)CMe(2)Cl) - BDE(het)(C(6)H(5)CMe(2)Cl)), for 16 of the 4-Y substituents employed by Brown and Okamoto. The plot of Delta BDE(het) vs sigma(p)+ gave rho(+) (SD) = 16.3 (2.3) kcal/mol, i.e., a rho(+) value roughly 2.5 times greater than experiment. Inclusion of solvation (water) energies, calculated using three continuum solvent models, reduced rho(+) and SD. The computationally least expensive model used, SM5.42R (Li et al. Theor. Chem. Acc. 1999, 103, 9) gave the best agreement with experiment. This model yielded rho(+) (SD) = 7.7 (0.9) kcal/mol, i.e., a rho(+) value that is only 24% larger than experiment.     

Microcalorimetric Investigation of Influence of Fungicide SYP-L190 on Growth Metabolism of Tetrahyrnena therrnophila and Bacillus thuringiensis

Flumorph (SYP‐L190) is a new systemic fungicide with good protective, curative and antisporulant activities but no phytotoxicity to certain plants. Its performance on the environmental ecosystem is unknown. Tetrahymena thermophila and Bacillus thuringiensis are two of biological indicators for the aquatic and soil environmental ecosystem respectively. Microcalorimetric technique based on the heat output was applied to evaluate the influence of fungicide flumorph (SYP‐L190) on the two microorganisms. The thermogenic curves and corresponding thermodynamic and thermokinetic parameters were obtained. SYP‐L190 at a concentration of 50–100 µg·mL^?1 had 5% –10% inhibitory ratios aganist Tetrahymena thermophila and was used as a protection reagent, while at a concentration of 100–200 µg·mL^?1 SYP‐L190 had 10% –20% inhibitory ratios and was used as a therapy reagent. The metabolic thermogenic curves of Bacillus thuringiensis contained bacterial growth phase and sporulation phase. The SYP‐L190 at a concentration of 0–200 µg·mL^?1 had no influence on bacterial growth phase, but led to a little lag of the sporulation phase with a constant heat output. Hormesis was obviously observed in present study.     

Fundamental aspects of quantum Brownian motion

With this work we elaborate on the physics of quantum noise in thermal equilibrium and in stationary nonequilibrium. Starting out from the celebrated quantum fluctuation-dissipation theorem we discuss some important consequences that must hold for open, dissipative quantum systems in thermal equilibrium. The issue of quantum dissipation is exemplified with the fundamental problem of a damped harmonic quantum oscillator. The role of quantum fluctuations is discussed in the context of both, the nonlinear generalized quantum Langevin equation and the path integral approach. We discuss the consequences of the time-reversal symmetry for an open dissipative quantum dynamics and, furthermore, point to a series of subtleties and possible pitfalls. The path integral methodology is applied to the decay of metastable states assisted by quantum Brownian noise.     

电磁理论中算符的一些性质

在本文中,把在不均匀各向异性介质中的麦克斯韦方程看作算符,它定义在一个有界区域,可以被理解为微波技术中的谐振腔。但在这腔中充填着铁氧体,等离子体或其他各向异性介质,这些介质在应用中日益重要。文中证明了在某些μ、ε和边界条件下,算符成为对称。而对称性和自伴性在本征函数展开中带来很多方便;此外我们推导了本征振动的正变性和互易定理。如果不满足对称性,引入伴谐振腔的概念,所谓伴谐振腔在几何形状上和原来的腔相同,但ε、μ和边界条件不一样。它和自伴谐振腔在正交性和互易定理上有某些相似之处。     

Diffusion theory of the positive column with two-stage ionization and collisional deexcitation

The diffusion theory of the low pressure positive column is extended to account for collisional deexcitation as well as for two-stage ionization by electron impact. This extension results in the equationn″(ξ)+n′(ξ)/ξ+n(ξ)+vn ²(ξ)[1+μn(ξ)]^-1=0, which is solved numerically for the value ofξ ₁ which satisfies the boundary conditionn(ξ ₁)=0 for different values of the parametersν andμ.     

关于波导管的格林张量函数

本文以本征函数展开的方法,研究了波导管中格林函数的一般性质和形式。为了得到波导管的本征函数(简正波)和格林张量函数的一些关系,我们首先对格林函数作富氏变换,它的象函数在各向同性介质波导中以并矢形式作为最简单的表达方法,而在充有各向异性介质波导中可以表为ABA⁺e^-ikz₀的形式,这里A是坐标矩阵。用这种方法详细推导了均匀各向同性介质波导中的并矢格林函数。 关键词：