Linear codes from support designs of ternary cyclic codes

Designs, Codes and Cryptography - For a long time, the literature has demonstrated that designs and codes are exciting topics for combinatorics and coding theory. Linear codes and t-designs are, in...     

Simultaneous quantification of levofloxacin,pefloxacin, ciprofloxacin and moxifloxacin in microvolumes of human plasma using high‐performance liquid chromatography with ultraviolet detection

Levofloxacin, pefloxacin, ciprofloxacin and moxifloxacin are four fluoroquinolones used in the treatment of serious bacterial infections. The antibacterial activity of fluoroquinolones is concentration dependent. Therefore, therapeutic drug monitoring in daily clinical practice is warranted to ensure the therapy's efficacy and prevent bacterial resistance. The purpose of the present study was to develop a method using high‐pressure liquid chromatography with an ultraviolet detector for simultaneous quantification of these four fluoroquinolones in human plasma. A 50 μL aliquot of plasma was precipitated by 200 μL of methanol using gatifloxacin as internal standard. The chromatographic separation was performed on a Kinetex XB‐C₁₈ column using a mobile phase composed of a mixture of orthophosphoric acid 0.4% (v/v), acetonitrile and methanol at a flow rate of 1.2 mL/min. Dual UV wavelength mode was used, with levofloxacin and moxifloxacin monitored at 293 nm, and pefloxacin and ciprofloxacin monitored at 280 nm. The calibration was linear over the ranges of 0.125–25 mg/L for levofloxacin, 0.1–20mg/L for moxifloxacin and 0.05‐10 mg/L for both pefloxacin and ciprofloxacin. Inter‐ and intra‐day trueness and precision were <13% for all the compounds under study. The proposed method was simple, reliable, cost‐effective and suitable for therapeutic drug monitoring or pharmacokinetics studies.     

Good polynomials for optimal LRC of low locality

Designs, Codes and Cryptography - According to a magnific method due to I. Tamo and A. Barg, a class of polynomials over finite fields, called good polynomials, was introduced and used to construct...     

Price coordination in distribution channels: A dynamic perspective

In this study, we investigate two important questions related to dynamic pricing in distribution channels: (i) Are coordinated pricing decisions efficient in a context where prices have carry-over effects on demand? (ii) Should firms practice a skimming or a penetration strategy if they choose to coordinate or to decentralize their activities? To answer these questions, we consider a differential game that takes place in a bilateral monopoly where the past retail prices paid by consumers contribute to the building of a reference price. The latter is used by consumers as a benchmark to evaluate the value of the product, and by firms to decide whether to adopt a skimming or a penetration strategy.     

Synthesis and coordination chemistry of ferrocenyl-1,2,3-triazolyl ligands

"Click" reactions between ethynylferrocene and mono-, bis-, and tris-azido aromatic derivatives yielded mono-, bis-, and tris-1,2,3-ferrocenyltriazoles (1, 2, and 3, respectively) as orange crystals. The X-ray crystal structure of the monoferrocenyltriazole compound 1 was solved with two nearly identical molecules within the asymmetric unit. In both molecules, the two Cp rings make a tilt angle of 2.1(3) degrees [0.7(3) degrees], and they are roughly eclipsed with a twist angle of 2.4(3) degrees [1.8(3) degrees]. Reaction of 1 with [PdCl2(PhCN)2] in dimethylsulfoxide (DMSO) yielded orange crystals of [PdCl2L2] (4; L=1), for which the X-ray crystal structure shows trans coordination to the nitrogen atom close to the ferrocene substitution. The Pd atom is located on an inversion center and displays a nearly perfect square planar environment. In DMSO-d6, 4 reversibly dissociates to regenerate 1, whose (1)H NMR spectrum is then observed. The 1H NMR study also shows that progressive addition of PdCl2 or [PdCl2(NCR)2] (R=Me or Ph) to DMSO-d6 solutions of 1 reversibly leads to the formation of 4 and the addition of excess PdII is necessary to lead to the complete disappearance of the signals of 1. The cyclic voltammograms of 1, 2, and 3 show the reversible oxidation wave of the ferrocenyl group, and that of 4 shows that this wave appears with increased intensity tentatively attributable to redox-catalyzed oxidation.     

Reactivity of an aminopyridine [LMnII]2+ complex with H2O2. Detection of intermediates at low temperature

In the present work we report the reactivity of [LMnII]2+ toward addition of hydrogen peroxide (H2O2) in acetonitrile solution, where L is a pentadentate polypyridine ligand. Formation of peroxo complexes is evidenced by low-temperature UV-visible spectroscopy, ESI-mass spectrometry, and EPR spectroscopy using parallel as well as perpendicular mode detection. The influence of the medium (basicity, water content) on the formation of various species is investigated. In basic nonanhydrous medium the fate of the reaction mixture solution is the formation of the di-mu-oxo mixed-valent Mn(III)Mn(IV) dinuclear complex. In acidic medium the building of the oxo bridges is avoided and the reaction mixture evolves toward oxidation of the ligand L. This reaction route offers new opportunities for the study of oxidation reactivity of Mn (hydro)peroxo complexes.     

Cooperative Advertising in a Marketing Channel

This paper examines dynamic advertising and promotion strategies in a marketing channel where the retailer promotes the manufacturer product and the manufacturer spends on advertising to build a stock of goodwill. We assume that sales depend on goodwill and promotion activities and that there are decreasing marginal returns to goodwill. Two scenarios are studied. First, the manufacturer and retailer determine noncooperatively their respective strategies. Second, the game is played à la Stackelberg with the manufacturer as the leader who supports partially the cost of the promotion activities of the retailer. In both cases, stationary Markovian strategies are characterized. These scenarios are examined also in the absence of decreasing marginal effect of goodwill on sales. The results show that, whether or not the goodwill stock has a decreasing marginal effect on sales, the cooperative advertising program is a coordinating mechanism in the marketing channel, i.e., both players receive higher payoffs.     

Characterization and Catalytic Properties of Aerogel Chromium Oxide Supported by Alumina or Silica

Alumina or silica supported chromium oxide catalysts prepared by sol-gel technique have been investigated by X-ray diffraction, BET analysis, combined diffuse reflectance spectroscopy, EPR and reduction-extraction by ethane 1,2 diol. The results reveal the presence of Cr³⁺, Cr⁵⁺ and Cr⁶⁺ ions. Chromium species Cr⁶⁺ are isolated and atomically dispersed on the alumina support as free chromate CrO ₄ ^2– while on silica, dichromate or polychromate species like Cr₂O ₇ ^2– or Cr₃O ₁₀ ^2– predominate. Chromium oxide exhibits a better catalytic properties for paraxylene partial oxidation, when it is supported on alumina. The difference of oxidation states and degree of oligomerisation of chromium on the two supports affects the catalytic properties.     

Dual role of price and myopia in a marketing channel

In this paper we study a dynamic two-player channel where the manufacturer controls the wholesale price and the investment in quality and the retailer chooses the retail price. We consider that the retail price affects both the demand and the perceived quality of the brand and that its variations contribute to the building of an internal reference price. One of the model’s distinctive features is that it accounts for the two meanings of price, i.e., its classical objective measure of the cost of acquiring a particular quantity of the product, and its subjective roles as an assessment of the quality of the product and an evaluation of gains or losses (deal vs. sacrifice) resulting from buying a “cheap” or an “expensive” product. This dual computation is done with respect to the internal reference price.