Intra-elemental photoelectron line intensities and their significance to quantitative analysis

Intraelemental relative photoelectron line intensities for 20 pure elements obtained under ultrahigh vacuum (5·10^?9 torr) and high resolution with cleaned surfaces are presented. Theoretical and experimental aspects of relative photoelectron line intensities as well as other characteristics of significance to quantitative analysis are discussed. Experimental data are related to theoretical results and compared with other recent work.     

Amperometric detection for liquid chromatographic separation of polynuclear hydrocarbons

Oxidative electrochemical detection is used for liquid chromatographic separation of polynuclear aromatic hydrocarbons (PAH's). The amperometric response is shown to be dependent on the working potential, ionic strength, flow rate, pH, temperature and pretreatment of the glassy carbon electrode surface. These experimental factors were optimized by choosing the maximum signal-to-noise ratio for anthracene and benz(a)-anthracene. The figures of merit (sensitivity, limit of detection and linear dynamic range) of six PAH's are reported and compared with ultraviolet absorption detection. Varying the applied potential gives the capability for selective detection.     

Tungstate sulfuric acid (TSA)/KMnO4 as a novel heterogeneous system for rapid deoximation

Neat chlorosulfonic acid reacts with anhydrous sodium tungstate to give tungstate sulfuric acid (TSA), a new dibasic inorganic solid acid in which two sulfuric acid molecules connect to a tungstate moiety via a covalent bond. A variety of oximes were oxidized to their parent carbonyl compounds under mild conditions with excellent yields in short times by a heterogeneous wet TSA/KMnO4 in dichloromethane system.     

Provably recursive functions of constructive and relatively constructive theories

In this paper we prove conservation theorems for theories of classical first-order arithmetic over their intuitionistic version. We also prove generalized conservation results for intuitionistic theories when certain weak forms of the principle of excluded middle are added to them. Members of two families of subsystems of Heyting arithmetic and Buss-Harnik’s theories of intuitionistic bounded arithmetic are the intuitionistic theories we consider. For the first group, we use a method described by Leivant based on the negative translation combined with a variant of Friedman’s translation. For the second group, we use Avigad’s forcing method.     

An efficient and facile synthesis of 3-amino-5-chromenyl-butenolides from 3-formyl chromone, dialkyl acetylenedicarboxylate, and primary amines

A three-component reaction of 3-formyl chromones, dialkyl acetylenedicarboxylate, and isocyanides in the presence of $\text{ POCl}_{3}$ was used as a highly efficient and practical approach for the synthesis of 3-amino-5-chromenyl-butenolides. High yields and high bond forming efficiency, and simple operations are the advantages of this method. Graphical abstract      

A dynamic pricing approach for returned products in integrated forward/reverse logistics network design

During the last decade, the stringent pressures from environmental and social requirements have spurred an interest in designing a reverse logistics network. In this paper, we address the problem of designing and planning a multi-echelon, multi-period, multi-commodity and capacitated integrated forward/reverse logistics network. Returned products are categorized with respect to their quality levels, and a different acquisition price is offered for each return type. Furthermore, the reservation incentive of customers, the expected price of customers for one unit of used product described by uniform distribution, is applied to model the customers’ return willingness. Due to the fact that the remaining worthwhile value in the used products is the corporation’s key motivation for buying them from customers, a dynamic pricing approach is developed to determine the acquisition price for these products and based on it determine the percentage of returned products collected from customer zones. The used products’ acquisition prices at each time period are determined based on the customers’ return willingness by each collection center.     

Lagrangian Description of World-Line Deviations

We introduce a Lagrangian which can be varied to give both the equation of motion and world-line deviations of spinning particles simultaneously.     

Role of sodium decoration on the methane storage properties of BC3 nanosheet

First-principles calculations including dispersion correction are carried out to investigate pristine and Na-decorated graphene-like BC₃ (h-BC₃) for their application as methane storage materials. Structural optimization shows that the methane is physisorbed on the pristine sheet via van der Waals forces with adsorption energy of ?2.7 kcal/mol. It was found that unlike the pristine graphene, sodium decorated sheet can effectively interact with the CH₄ molecule, so that each metal atom bound on sheet may adsorb up to four CH₄. Furthermore, no bond dissociation was observed for the adsorption of CH₄ on Na-decorated h-BC₃, which means that decorated sheet can act as a storage device for methane safety storage. The results indicate that decoration of the Na atom on surface of sheet induces significant changes in electronic properties of the sheet and its E _g is unchanged after adsorption of CH₄ molecules. Theoretical methane storage capacity of Na-decorated BC₃ nanosheet could approach 18.1 wt%.     

Preparation and Characterization of DGEBA/EPN Epoxy Blends with Improved Fracture Toughness

The physical and mechanical properties of blends composed of two kinds of epoxy resins of different numbers of functional groups and chemical structure were studied.One of the resins was a bifunctional epoxy resin based on diglycidyl ether ofbisphenol A and the other resin was a multifunctional epoxy novolac resin.Attempt was made to establish a correlation between the structure and the final properties of cured epoxy samples.The blend samples containing high fraction of multifunctional epoxy resin showed higher solvent resistance and lower flexural modulus compared with the blends containing high fraction of bifunctional epoxy resin.The epoxy blends showed significantly higher ductility under bending test than the neat epoxy samples.The compressive modulus and strength increased with increasing of multifunctional epoxy in the samples,probably due to enhanced cross-link density and molecular weight.Morphological analysis revealed the presence of inhomogeneous sub-micrometer structures in all samples.The epoxy blends exhibited significantly higher fracture toughness (by 23％ at most) compared with the neat samples.The improvement of the fracture toughness was attributed to the stick-slip mechanism for crack growth and activation of shear yielding and plastic deformation around the crack growth trajectories for samples with higher content of bifunctional epoxy resin as evidenced by fractography study.