Ionic‐Liquid‐Derived,Water‐Soluble Ionic Cellulose

A new type of water‐soluble ionic cellulose was obtained by means of the dissolution of cellulose in dimethylimidazolium methylphosphite at elevated temperatures over 120 °C. FTIR spectroscopy, ¹H and ¹³C NMR spectroscopy, and elemental analysis results revealed that the repeating unit of the water‐soluble cellulose consists of a dialkylimidazolium cation and a phosphite anion bonded to cellulose. The degree of phosphorylation on the cellulose chain was between 0.4 and 1.3 depending on the reaction temperature and time. With an increasing degree of phosphorylation, water solubility was increased. Scanning electron microscopy and X‐ray diffraction analyses revealed that the cellulose crystalline phase in the parent crystalline cellulose changed to an amorphous phase upon transformation into ionic cellulose. Thermogravimetric analysis showed the prepared phosphorylated cellulose was stable over 250 °C and a substantial amount of residue remained at 500 °C.     

Monomer–Dimer Equilibrium for the 5′–5′ Stacking of Propeller‐Type Parallel‐Stranded G‐Quadruplexes: NMR Structural Study

Guanine‐rich sequence motifs, which contain tracts of three consecutive guanines connected by single non‐guanine nucleotides, are abundant in the human genome and can form a robust G‐quadruplex structure with high stability. Herein, by using NMR spectroscopy, we investigate the equilibrium between monomeric and 5′–5′ stacked dimeric propeller‐type G‐quadruplexes that are formed by DNA sequences containing GGGT motifs. We show that the monomer–dimer equilibrium depends on a number of parameters, including the DNA concentration, DNA flanking sequences, the concentration and type of cations, and the temperature. We report on the high‐definition structure of a simple monomeric G‐quadruplex containing three single‐residue loops, which could serve as a reference for propeller‐type G‐quadruplex structures in solution.     

Crystal and molecular structures of selected oxidative nitration products of aminopyrazine and 2-amino-3-hydroxypyridine

2,3,5,6-Tetraoxopiperazine (I), ammonium 2,3,5,6-tetraoxo-4-nitropyridinate crystal hydrate (II), co-crystallized dimethylammonium 2,3,5,6-tetraoxo-4-nitropyridinate and dimethylammonium chloride (III), and ammonium 2,6-dioxo-3,5-dinitropyridinate (IV) were isolated in the crystalline state and studied by X-ray diffraction. All heterocycles are planar and nonaromatic. They consist of two conjugated moieties linked together by C-C single bonds. The short C...O contacts (2.841–3.048 Å), which link the molecules to form zigzag two-dimensional chains, make a considerable contribution to the formation of the crystal structure of I, whereas hydrogen bonds that form three-dimensional networks play the most important role in the formation of the crystals of II–IV.     

Generalized Differentiation of a Class of Normal Cone Operators

This paper investigates generalized differentiation of normal cone operators to parametric smooth-boundary sets in Asplund spaces. We obtain formulas for computing the Fréchet and Mordukhovich coderivatives of such normal cone operators. We also give several examples to illustrate how the formulas can be used in practical calculations and applications.     

Steady-state skill levels of workers in learning and forgetting environments: A dynamical system analysis

This article presents a study on the long-term (i.e., steady-state, convergence) characteristics of workers’ skill levels under learning and forgetting in processing units in a manufacturing environment, in which products are produced in batches. Assuming that all workers already have the basic knowledge to execute the jobs, workers learn (accumulate their skill) while producing units within a batch, forget during interruptions in production, and relearn when production resumes. The convergence properties in the paper are examined under assumptions of an infinite time horizon, a constant demand rate, and a fixed lot size. Our work extends the steady-state results of Teyarachakul, Chand, and Ward (2008) to the learning and forgetting functions that belong to a large class of functions possessing some differentiability conditions. We also discuss circumstances of manufacturing environments where our results would provide useful managerial information and other potential applications.     

New inequalities for q-ary constant-weight codes

Using double counting, we prove Delsarte inequalities for \(q\) -ary codes and their improvements. Applying the same technique to \(q\) -ary constant-weight codes, we obtain new inequalities for \(q\) -ary constant-weight codes.     

Optimal resource acquisition policy for a newsvendor under supply risk

We consider a single-period manufacturing problem involving uncertainty in the availability of a production resource. The resource is stochastically available at the regular cost, but by paying a premium it is possible to reserve and hence guarantee any desired level of the resource in advance. Given the resource consumption rates for a number of products, the manufacturer needs to determine the optimal forward purchase quantity of the resource such that expected profit from selling the products is maximized. The problem is formulated as an extension of the traditional multi-item newsvendor problem. A computational optimization procedure is developed for solving the problem. We find that depending on the profit margins associated with the products, the optimal reservation amount of the resource may increase or decrease as the supply variability increases. The demand volatilities of products are observed to influence the forward purchase quantity of the resource in a similar manner.     

Raman characterization of localized CdS nanostructures synthesized by UV irradiation in sol–gel silica matrices

A new technique of UV irradiation has been used for the first time to create microstructures of CdS nanoparticles in bulk xerogels. Porous silica matrices, which were first soaked in a solution containing CdS precursors, were subjected to irradiation using a nanopulsed ArF laser with a wavelength of 193 nm and a repetition rate of 10 Hz. Resonant micro‐Raman spectra, recorded using the 325‐nm line of a He‐Cd laser (with a continuous power less than 0.5 mW so as to avoid the thermal formation of nanoparticles) made it possible to identify CdS nanoparticles within the inscribed yellow zones and also to estimate the average particle size (3.6 to 8.0 nm, depending on the number of UV pulses used). The emission of CdS particles embedded in the silica matrix under excitation at 351.1 nm was studied by photoluminescence spectroscopy. It was then possible to show the effect of the number of pulses on the electronic structure of the nanocrystals. Finally, Raman spectra were used to monitor the structural changes in the silica matrix caused by the irradiation. It was found that the pulsed UVirradiation resulted in a local densification of the matrix, which was compensated for by a depolymerization process of the Si O Si network. In spite of this pulsed irradiation and the resulting structural depolymerization, no apparent ablation or cracking of the samples was observed. Copyright © 2010 John Wiley & Sons, Ltd.     

Capillary electrochromatography with contactless conductivity detection for the determination of some inorganic and organic cations using monolithic octadecylsilica columns

A fast separation of alkali and alkaline earth metal cations and ammonium was carried out by capillary electrochromatography on monolithic octadecylsilica columns of 15 cm length and 100 μm inner diameter using water/methanol mixtures containing acetic acid as mobile phase. On-column contactless conductivity detection was used for quantification of these non-UV-absorbing species. The method was also extended successfully to the determination of small amines as well as of amino acids, and the separation selectivity was optimized by varying the composition of the mobile phase. Detection limits of about 1 μM were possible for the inorganic cations as well as for the small amines, while the amino acids could be quantified down to about 10 μM. The separation of 12 amino acids was achieved in the relatively short time of 10 min.