Diamond D5 is a hyperdiamond structured as coalesced C20 and C28 small fullerenes, in the ratio 2:1, and having up to 90?% pentagonal rings while the others being hexagonal. Design of several precursors, intermediates, and crystal networks was performed using our original software programs CVNet and Nano-Studio. Energetic data, calculated at DFT and DFTB levels of theory revealed a stability of these structures close to that of classical diamond. A lonsdaleite-like structure is also discussed. The topology of these networks is described in terms of the net parameters and the net characteristics in crystallographic terms. 相似文献
Certain purchasing groups do not flourish. A supposed reason for this is a creeping dissatisfaction among various members of a group with the allocation of the cooperative gains. In this paper, we analyze unfairness resulting from using the commonly used Equal Price (EP) method for allocating gains under the assumption of continuous quantity discounts. We demonstrate that this unfairness is caused by neglecting a particular component of the added value of individual group members. Next, we develop two fairness ratios and tie these to fairness properties from cooperative game theory. The ratios show among other things that being too-big a player in a purchasing group can lead to decreasing gains. They can be used to assess if EP is an unfair method in specific situations. Finally, we discuss measures a purchasing group could consider in order to attenuate perceived unfairness. Thereby, the group may improve its stability and prosperity. 相似文献
Various aryl carboxamides with alkoxy substituents at the ortho-position, applicable as direct intermediates toward novel ligands, were synthesised via aminocarbonylation of aryl-iodides (2-iodoanisole, 5-chloro-7-iodo-8-methoxy-quinoline, and 5-chloro-7-iodo-8-benzyloxy-quinoline) in the presence of in situ generated palladium(0) catalysts. Simple primary and secondary amines as well as aminoacid esters were used as N-nucleophiles. The optimization of the reaction conditions allowed the preferential formation of carboxamides or ketocarboxamides by simple or double carbon monoxide insertion, respectively. A strong dependence of the chemoselectivity on carbon monoxide pressure was observed. 相似文献
Bergenia species (Saxifragaceae) are important sources of herbal medicines in Asia, mainly in Russia. Various plant parts are valued for their antibacterial, anti-inflammatory, antioxidant sand adaptogenic effect, and used for the dissolution of kidney and bladder stones. In this study a rapid reversed phase liquid chromatography (RP-HPLC) method has been developed for rapid screening and identifying of the main active components in leaf samples of Bergenia accessions. The main goal of this study was to develop an efficient method for the simultaneous identification and detection of arbutin, bergenin and gallic acid from Bergenia leaf samples, which were extracted with a methanolic solvent mixture [methanol:water = 1:1 (v/v)]. Chromatographic separations were performed on a reversed phase Luna C18(2)-HST HPLC column. This chromatographic system provided increased speed and efficiency for separations, without the need for ultra-high pressures. Reversed phase HPLC coupled with diode array detector method was used for the analysis. The method was validated using ICH guidelines. The level of gallic acid was significantly higher in Bergenia crassifolia samples compared to Bergenia cordifolia. However, the samples of the two Bergenia species did not differ substantially regarding the concentrations of arbutin and bergenin. The novel method proved to be fast and allowed sufficient separation and quantification of arbutin, bergenin and gallic acid, the most important bioactive compounds of Bergenia leaves; thus facilitating rapid screening and quality assessment of Bergenia samples of various botanical and geographical origins.
MDS codes are codes meeting the Singleton bound. Both for theory and practice, these codes are very important and have been studied extensively. Codes near this bound, but not attaining it, have had far less attention. In this paper we study codes that almost reach the Singleton bound. 相似文献