Rental price and rental duration under retail competition

Consider a retailer that rents products to customers for a pre-specified rental duration. By considering the dynamics of uncertain rental demand and return processes, we first present a base model that is intended to analyze the impact of rental duration on the stocking level, the rental price, and the retailer’s profit. Due to the complexity of the base model, we develop an approximation scheme to obtain tractable results. Also, we apply the base model to analyze a situation in which a retailer enters a revenue sharing agreement with a distributor. Moreover, we expand our base model to address the issue of competition in rental duration and rental price. The analysis of our competitive model in a duopolistic environment suggests that the market equilibrium depends on the market potential and the rental duration sensitivity. Furthermore, we establish conditions under which one firm will charge a lower rental price while the other firm will offer a longer rental duration in equilibrium.     

Asymmetric multicomponent reactions: diastereoselective synthesis of substituted pyrrolidines and prolines

A novel diastereoselective synthesis of substituted pyrrolidines has been developed. Asymmetric multicomponent reactions of optically active phenyldihydrofuran, N-tosyl imino ester, and silane reagents in a one-pot operation afforded highly substituted pyrrolidine derivatives diastereoselectively. The reaction is quite efficient and constructed up to three stereogenic centers in a single operation.     

The Binomial k‐Clique

A finite collection C of k‐sets, where is called a k‐clique if every two k‐sets (called lines) in C have a nonempty intersection and a k‐clique is a called a maximal k‐clique if and C is maximal with respect to this property. That is, every two lines in C have a nonempty intersection and there does not exist A such that , and for all . An elementary example of a maximal k‐clique is furnished by the family of all the k‐subsets of a ‐set. This k‐clique will be called the binomial k‐clique. This paper is intended to give some combinatorial characterizations of the binomial k‐clique as a maximal k‐clique. The techniques developed are then used to provide a large number of examples of mutually nonisomorphic maximal k‐cliques for a fixed value of k.     

Pharmacokinetic Analysis of Ursolic Acid in Alstonia scholaris R. Br. by High-Performance Thin-Layer Chromatography

JPC – Journal of Planar Chromatography – Modern TLC - A simple and rapid high-performance thin-layer chromatographic method has been established and validated for determination of...     

Variational functions of the padé type—application to the ground state of the helium atom

It is shown that trial functions involving Padé approximants yield satisfactory results for the ground state of the helium atom. In particular, the five-parameter form reproduces the best variational function of the type Ψ = e^–zs?(u) obtained numerically, to a remarkable extent.     

A NEW GLOW PEAK, IN RHODOPSEUDOMONAS SPHAEROIDES

Abstract— A new glow peak at 120 K has been observed in Rhodopseudomanas sphaeroides and in its carotenoidless green mutant. This peak (labelled Z_n ), which is composed of two peaks at 120 and 150 K, appears when the bacteria are illuminated with white light while being cooled to 77 K and then warmed in darkness at a heating rate of 10 K per min. Delayed light emission and prompt fluorescence spectra show peaks around 530, 610 and 660 nm. The action spectra of light emission show a major peak at 410 nm and a smaller peak around 545 nm. The pigment responsible for the light emission is also leached out in the suspension medium. The chromophore responsible for the light emission appears to be magnesium protoporphyrin IX, not bacteriochlorophyll.     

The platinum-20% rhodium electrode in potentiometry

The performance of a platinum-20% rhodium alloy indicator electrode is studied in a number of potentiometric redox and acid-base titrations and compared with that of the conventional platinum electrode. The potential breaks obtained with the alloy electrode are always smaller than those obtained with the platinum electrode. The end-points are also usually indicated later than the true end-points. The bimetallic electrode system comprising platinum and platinum-rhodium electrodes gives a peak at the correct end-point even with 0.001N concentration titrations, where the ordinary potentiometric systems do not always give good results.     

发展中国家化学实验教学的现代化——挑战与机会

在多数发展中国家,中学及大专院校的化学实验教学呈现一幅沉闷景象。近30年来实验课在很多国家一直不太景气,尽管科研和生产实验室中使用计算机化数据处理支持的复杂的高科技仪器已是很平常的事情,但学生实验室却穷得连pH计、比色计这样最简单的仪器也没有。     

Simultaneous CO concentration and temperature measurements using tunable diode laser absorption spectroscopy near 2.3 μm

Simultaneous measurements of carbon monoxide (CO) mole fraction and temperature using tunable diode laser absorption spectroscopy (TDLAS) near 2.3 μm are reported. The measurement method uses ro-vibrational transitions [R(27): v″ = 1 → v′ = 3] and [R(6): v″ = 0 → v′ = 2] in the first overtone band of CO near 2.3 μm (~4,278 cm^?1). The measurements were performed in the post flame environment of fuel rich premixed ethylene–air flames with a N₂ co-flow, stabilized over a water cooled McKenna burner. Non-uniformity in the temperature and CO mole fraction, along the absorption line of sight, in the mixing layer of the co-flow, was considered during data analysis. The TDLAS based temperature measurements (±80 K) were in good agreement with those obtained using N₂ vibrational coherent anti-Stokes Raman scattering (±20 K), and the CO mole fraction measurements were in good agreement with the equilibrium values, for equivalence ratios lower than 1.8. A signal to noise ratio of 45 was achieved at an equivalence ratio of 1 for a CO concentration of 0.8 % at 1,854 K.     

Reductive Studies on 3-Oxidopyrylium-alkene [5 + 2] Cycloadducts: Access to Some Hydroxy Cycloheptenoids

The scope of nickel boride as a versatile reducing reagent is extended to the 3-oxidopyrylium-alkene [5 + 2] cycloadducts. In this report, we demonstrate that nickel boride is capable of one-pot 1,2- and 1,4-reduction of enones present in the cycloadducts in good yields. Subsequent elaboration of the cycloadducts towards synthesis of functionalized cycloheptenoid derivatives devoid of the oxa-bridge is also explored.