Does chiral symmetry breaking cause the Nucleon-Delta mass difference?

We critically review recent calculations of the Nucleon-Delta mass splitting in the QCD sum rule approach. Some calculations indicate aN-Δ mass splitting already to zeroth order QCD, i.e., only due to the chiral symmetry breaking quark condensate. We show that there is no indication of a mass splitting to zeroth order if optimal interpolating fields are used for theN and Δ, where optimal fields are those for which the continuum contribution is minimal.     

Mitigation of cellulose recalcitrance to enzymatic hydrolysis by ionic liquid pretreatment

Efficient hydrolysis of cellulose-to-glucose is critically important in producing fuels and chemicals from renewable feedstocks. Cellulose hydrolysis in aqueous media suffers from slow reaction rates because cellulose is a water-insoluble crystalline biopolymer. The high-crystallinity of cellulose fibrils renders the internal surface of cellulose inaccessible to the hydrolyzing enzymes (cellulases) as well as water. Pretreatment methods, which increase the surface area accessible to water and cellulases are vital to improving the hydrolysis kinetics and conversion of cellulose to glucose. In a novel technique, the microcrystalline cellulose was first subjected to an ionic liquid (IL) treatment and then recovered as essentially amorphous or as a mixture of amorphous and partially crystalline cellulose by rapidly quenching the solution with an antisolvent. Because of their extremely low-volatility, ILs are expected to have minimal environmental impact. Two different ILs, 1-n-butyl-3-methylimidazolium chloride (BMIMC1) and 1-allyl-3-methylimidazolium chloride (AMIMC1) were investigated. Hydrolysis kinetics of the IL-treated cellulose is significantly enhanced. With appropriate selection of IL treatment conditions and enzymes, the initial hydrolysis rates for IL-treated cellulose were up to 90 times greater than those of untreated cellulose. We infer that this drastic improvement in the "overall hydrolysis rates" with IL-treated cellulose is mainly because of a significant enhancement in the kinetics of the "primary hydrolysis step" (conversion of solid cellulose to soluble oligomers), which is the rate-limiting step for untreated cellulose. Thus, with IL-treated cellulose, primary hydrolysis rates increase and become comparable with the rates of inherently faster "secondary hydrolysis" (conversion of soluble oligomers to glucose).     

Low-energy modes and Debye behavior in a colloidal crystal

We study the vibrational spectrum and the low-energy modes of a three-dimensional colloidal crystal using confocal microscopy. This is done in a two-dimensional cut through a three-dimensional crystal. We find that the observed density of states is incompatible with the standard Debye form in either two or three dimensions. These results are confirmed by numerical simulations. We show that an effective theory for the projections of the modes onto the two-dimensional cut describes the experimental and simulation data in a satisfactory way.     

8-羟基喹啉过渡金属配合物电子光谱和二阶非线性光学性质的 DFT研究

使用含时密度泛函理论(TDDFT)B3LYP方法计算了IB, IIB, VIIIB过渡金属与8-羟基喹啉络合(MQ)后, 配合物的电子光谱以及二阶非线性光学性质. 结果表明, 掺杂过渡金属后, 形成络合物的能隙值减小100～150 kJ/mol, 最大吸收波长红移150～200 nm左右. 电子从基态到激发态的跃迁主要为p→p*, n→p*跃迁, 属于LLCT, MLCT过程. IB的络合物MQ以及VIIIB的络合物MQ3表现出良好的非线性光学性质.     

“下愚”最智 “上智”最愚

历代反动派总是宣扬孔老二“上智与下愚不移”的唯心论说教,把它作为“剥削有理”、“压迫有理”的根据。林彪这个地主资产阶级的代理人,为了篡党夺权,复辟资本主义,建立林家法西斯王朝,也鼓吹“上智下愚”的谬论。他把自己吹成“生而知之”的“天才”,以“至贵”、超人自居,污蔑劳动人民“愚昧”、“落后”,只会说“恭喜发财”,只能想“油盐酱醋柴”。     

Photoinduced intramolecular charge separation in donor/acceptor-substituted bicyclohexylidene and bicyclohexyl

The photophysical properties of a bicyclohexylidene (1DA) and a bicyclohexyl (2DA) substituted with an anilino electron donor and a dicyanoethylene electron acceptor have been studied. Quenching of local donor emission is observed for these compounds as well as quenching of the "pseudo-local" acceptor emission. Transient absorption spectra show dialkylanilino-type radical-cation and dicyanoethylene-type radical-anion absorptions. These results show that intramolecular charge separation takes place in 1DA and 2DA. This was corroborated by time-resolved microwave conductivity measurements from which large excited-state dipole moments were found for both 1DA and 2DA. Time-resolved fluorescence spectroscopy revealed that in the charge-separated state in cyclohexane for 2DA, molecular folding takes place on a nanosecond timescale. For 1DA in cyclohexane, either charge separation takes place in a (fully) folded conformation or very rapid (subnanosecond timescale) folding takes place subsequent to charge separation. In addition to this difference in conformational behavior, the presence of the exocyclic double bond between the cyclohexyl-type rings results in efficient quenching of the anilino donor triplet state and acceleration of the charge recombination rate by a factor of 20.     

Isothermal and non-isothermal melting of the binary solution inside an emulsion

The aim of the present paper is to study the melting process inside an emulsion using the non-equilibrium model of microscopic heat transfer between the emulsifying medium and the dispersed droplet of binary solution (DSC). DSC experiments are used to validate the numerical results. The effects of the heating rate, mass fraction of the dispersed saline binary solution, initial mass fraction of the solute and the sample mass on the kinetics of the melting process are examined.