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31.
Suppliers network in the global context under price discounts and uncertain fluctuations of currency exchange rates have become critical in today’s world economy. We study the problem of suppliers’ selection in the presence of uncertain fluctuations of currency exchange rates and price discounts. We specifically consider a buyer with multiple sites sourcing a product from heterogeneous suppliers and address both the supplier selection and purchased quantity decision. Suppliers are located worldwide and pricing is offered in suppliers’ local currencies. Exchange rates from the local currencies of suppliers to the standard currency of the buyer are subject to uncertain fluctuations overtime. In addition, suppliers offer discounts as a function of the total quantity bought by the different customer’ sites over the time horizon irrespective of the quantity purchased by each site. 相似文献
32.
Yufeng Jiang Ramzi Chakroun Peiyang Gu Andr H. Grschel Thomas P. Russell 《Angewandte Chemie (International ed. in English)》2020,59(31):12751-12755
Soft polymeric Janus nanoparticles (JNPs), made from polystyrene‐b‐poly(butadiene)‐b‐poly(methylmethacrylate), PS‐PB‐PMMA, triblock terpolymers, assemble into a monolayer at the water–oil interface to reduce interfacial tension. The extent to which the polymer chains can deform influences the packing density of the JNPs at the interface. The longer the polymer chains are relative to the core, the softer are the JNPs, resulting in a JNPs assembly with a lower initial lateral packing density. The interfacial activity of JNPs can be further tuned by complexation of the PMMA chains with lithium ions that are introduced into the water phase. This work provides a fundamental understanding of soft JNPs packing at the water–oil interface and provides a strategy to tailor the areal density of soft JNPs at liquid–liquid interface, enabling the design of smart responsive structured‐liquid systems. 相似文献
33.
G. Mastrocinque A. Chakroun L. Doyennette H. Gueguen M. Margottin-Maclou L. Henry 《Chemical physics letters》1976,39(2):347-349
V-V transfer rates from CO (υ = 1) to 14N2 and 15N2 are determined from 100 to 700 K using the laser fluorescence method. The great effect of the energy level gap between the colliding partners is dramatically demonstrated. Theoretical considerations explain the observed difference. 相似文献
34.
Ramzi Ksouri 《Applied Categorical Structures》2016,24(3):283-314
We define the notion of duality categories as generalization of duality groups. Two examples are treated. The first is the Serre duality in the categories of strict polynomial functors. The second concerns finite complexes. We show in particular that finite Tits buildings are duality categories. 相似文献
35.
Densities, viscosities, and ionic conductivities were measured for the binary mixtures containing the ionic liquid N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide and methanol over the entire range of compositions at the temperature
varying from 253.15 to 318.15 K. The densities and viscosities decrease monotonously with temperature and the content of ionic
liquids (ILs). Furthermore, excess isobaric expansion coefficient has been calculated from the experimental densities. The
dependence of temperature on the viscosity has been fitted to the Arrhenius law with high precision. The dependence of temperature
on the ionic conductivity has also been gauged by both of the Arrhenius and Vogel–Tamman–Fulcher (VTF) equations. In fact,
the shape of the curves shows that the temperature dependence of the conductivity does not follow a simple Arrhenius law,
but a better fitting of experimental results is achieved using the VTF model. Additionally, the effects of ILs concentration
on the viscosity and the conductivity have been examined using the Walden rule, which shows that the variation of conductivity
is inversely proportional to viscosity. Excess molar volumes and viscosity deviations for all mixtures are evaluated and well
fitted to the Redlich–Kister polynomial expansions. Physicochemical properties show two clearly distinguished behaviors corresponding
to ILs-rich and methanol-rich regions, with distinct transport and volumetric properties. The obtained results are discussed
in terms of dipolar interactions and hydrogen bonding establishment between ions of ILs and the methanol molecules. 相似文献
36.
Dalençon S Youcef RA Pipelier M Maisonneuve V Dubreuil D Huet F Legoupy S 《The Journal of organic chemistry》2011,76(19):8059-8063
The asymmetric synthesis of novel cyclohexene nucleoside analogues 12 and 15 is described. An enantiospecific Diels-Alder reaction between (E,E)-diene 2 and (+)-5-(d-mentyloxy)-2(5H)-furanone 3 provided the cycloadduct isomer 4. Three additional steps yielded amine 8 allowing the constructions of the thymine and adenine moieties to afford intermediates 11 and 14, respectively. Amination or cyclization and removal of the protecting groups occurred in one step in the presence of ammonia, giving the target six-membered ring nucleosides. 相似文献
37.
Miiller W Avdeev M Zhou Q Kennedy BJ Sharma N Kutteh R Kearley GJ Schmid S Knight KS Blanchard PE Ling CD 《Journal of the American Chemical Society》2012,134(6):3265-3270
As compared to 3d (first-row) transition metals, the 4d and 5d transition metals have much more diffuse valence orbitals. Quantum cooperative phenomena that arise due to changes in the way these orbitals overlap and interact, such as magnetoelasticity, are correspondingly rare in 4d and 5d compounds. Here, we show that the 6H-perovskite Ba(3)BiIr(2)O(9), which contains 5d Ir(4+) (S = 1/2) dimerized into isolated face-sharing Ir(2)O(9) bioctahedra, exhibits a giant magnetoelastic effect, the largest of any known 5d compound, associated with the opening of a spin-gap at T* = 74 K. The resulting first-order transition is characterized by a remarkable 4% increase in Ir-Ir distance and 1% negative thermal volume expansion. The transition is driven by a dramatic change in the interactions among Ir 5d orbitals, and represents a crossover between two very different, competing, ground states: one that optimizes direct Ir-Ir bonding (at high temperature), and one that optimizes Ir-O-Ir magnetic superexchange (at low temperature). 相似文献
38.
Madeeha Aslam Fozia Fozia Anadil Gul Ijaz Ahmad Riaz Ullah Ahmed Bari Ramzi A. Mothana Hidayat Hussain 《Molecules (Basel, Switzerland)》2021,26(20)
Green synthesis of silver nanoparticles (AgNPs) employing an aqueous plant extract has emerged as a viable eco-friendly method. The aim of the study was to synthesize AgNPs by using plant extract of Sanvitalia procumbens (creeping zinnia) in which the phytochemicals present in plant extract act as a stabilizing and reducing agent. For the stability of the synthesized AgNPs, different parameters like AgNO3 concentration, volume ratios of AgNO3, temperature, pH, and contact time were studied. Further, AgNPs were characterized by UV–visible spectroscopy, FT-IR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy), and EDX (Energy Dispersive X-ray Spectrometer) analysis. FT-IR analysis showed that the plant extract contained essential functional groups like O–H stretching of carboxylic acid, N–H stretching of secondary amides, and C–N stretching of aromatic amines, and C–O indicates the vibration of alcohol, ester, and carboxylic acid that facilitated in the green synthesis of AgNPs. The crystalline nature of synthesized AgNPs was confirmed by XRD, while the elemental composition of AgNPs was detected by energy dispersive X-ray analysis (EDX). SEM studies showed the mean particle diameter of silver nanoparticles. The synthesized AgNPs were used for photocatalytic degradation of Orange G and Direct blue-15 (OG and DB-15), which were analyzed by UV-visible spectroscopy. Maximum degradation percentage of OG and DB-15 azo dyes was observed, without any significant silver leaching, thereby signifying notable photocatalytic properties of AgNPs. 相似文献
39.
[reaction: see text] The design and development of an effective protocol for the palladium-catalyzed cross-coupling of (E)- and (Z)-heptenyldimethylsilanols with organo-triflates and nonaflates is described. Optimization of this coupling focused on the issues of both reactivity and stability of the psuedohalides in the presence of the nucleophilic fluoride promoter for the coupling. The crucial role of varying amounts of water to modulate the reactivity of the fluoride ion is highlighted. 相似文献
40.
W. Nachit S. Touhtouh Z. Ramzi M. Zbair A. Eddiai M. Rguiti 《Molecular Crystals and Liquid Crystals》2016,627(1):170-175
ABSTRACTNanotechnology is all about making products from very small constituents, components or subsystems to gain greatly enhanced material properties and functionality. Nanocrystalline anatase TiO2 was prepared by a facile sol–gel route at a temperature of 50°C under mild conditions. Titanium tetraisopropoxide (TTIP) was used as a titanium precursor, and 2-propanol was used as a solvent. XRD, TEM, SEM, FT-IR and BET were applied to characterize the crystal phase. The Crystalline size of TiO2 powder has been obtained with diameter < 30 nm for anatase at 500°C using an acid. 相似文献