A Discrete Bochner�CMartinelli Formula

In the even dimensional case the discrete Dirac equation may be reduced to the so-called discrete isotonic Dirac system in which suitable Dirac operators appear from both sides in half the dimension. This is an appropriated framework for the development of a discrete Martinelli–Bochner formula for discrete holomorphic functions on the simplest of all graphs, the rectangular \mathbbZ^m{\mathbb{Z}^m} one. Two lower-dimensional cases are considered explicitly to illustrate the closed analogy with the theory of continuous variables and the developed discrete scheme.     

Surface-functionalized Carbon Black as Catalyst for the Direct Production of Hydrogen Peroxide by the Oxidation of Hydroxylamine

Carbon black (CB) without micropores was functionalized by mixed acid and used to explore the surface chemistry effect on the production of hydrogen peroxide (H₂O₂). The CB materials were characterized by N₂ adsorption‐desorption, XRD, SEM, FTIR, and TPD. The results of different characterization methods indicated that both the textural features and the surface chemical properties of CB were significantly modified by the acidic treatment. The catalytic performance of the modified CBs for hydroxylamine (NH₂OH) oxidation increased with increasing the surface oxygen‐containing species. The yield of H₂O₂ approached 30% with the corresponding concentration of 73.9 mmol·L^?1 (w=0.25%) over the most promising CB catalyst, which was much superior to the results obtained on supported noble metals. Correlations between catalytic activity and concentration of different surface functional groups on the CB samples confirmed that the quinonoid species might be the active species.     

Fast multidimensional localized parallel NMR spectroscopy for the analysis of samples

A parallel localized spectroscopy (PALSY) method is presented to speed up the acquisition of multidimensional NMR (nD) spectra. The sample is virtually divided into a discrete number of nonoverlapping slices that relax independently during consecutive scans of the experiment, affording a substantial reduction in the interscan relaxation delay and the total experiment time. PALSY was tested for the acquisition of three experiments 2D COSY, 2D DQF‐COSY and 2D TQF‐COSY in parallel, affording a time‐saving factor of 3–4. Some unique advantages are that the achievable resolution in any dimension is not compromised in any way: it uses conventional NMR data processing, it is not prone to generate spectral artifacts, and once calibrated, it can be used routinely with these and other combinations of NMR spectra. Copyright © 2010 John Wiley & Sons, Ltd.     

Density functional study for the polymerization of ethylene monomer using a new nickel catalyst

The present computational study was designed to study the polymerization of ethylene catalyzed by a new Ni‐based PymNox organometallic compound. Recently, we have synthesized and tested the behavior of this type of catalyst in olefin polymerization. It has been experimentally observed that the unsubstituted catalyst Ni2 (aldimino PymNox catalyst ) is less active than the methyl substituted Ni1 (acetaldimino PymNox catalyst ) analogue. The reactivity of both catalysts was examined using density functional theory (DFT) models. Our results indicate that the methyl substituted Ni1 introduces some additional steric hindrance that probably renders a more suitable catalyst conformation for the monomer incorporation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1160–1165, 2010     

A Novel Method for Fabrication of a Glass-Electrode-Based Lipase Sensor

Lipase is one of the hydrolases. It catalyzes the hydrolysis of triglycerides, liberating fat acids. Based on its catalysis and the response of a glass electrode to the acids, a glass-electrode-based lipase sensor can be fabricated1, which has great potential in clinical medicine for the detection of blood fat in human serum samples.The immobilization of lipase on the bulb of a glass electrode is the key to the development of the sensor. In addition to its response time, which has a lot to do …     

Probabilistically induced domain decomposition methods for elliptic boundary-value problems

Monte Carlo as well as quasi-Monte Carlo methods are used to generate only few interfacial values in two-dimensional domains where boundary-value elliptic problems are formulated. This allows for a domain decomposition of the domain. A continuous approximation of the solution is obtained interpolating on such interfaces, and then used as boundary data to split the original problem into fully decoupled subproblems. The numerical treatment can then be continued, implementing any deterministic algorithm on each subdomain. Both, Monte Carlo (or quasi-Monte Carlo) simulations and the domain decomposition strategy allow for exploiting parallel architectures. Scalability and natural fault tolerance are peculiarities of the present algorithm. Examples concern Helmholtz and Poisson equations, whose probabilistic treatment presents additional complications with respect to the case of homogeneous elliptic problems without any potential term and source.     

Stress Inhomogeneity in Powder Specimens Tested in the Jenike Shear Cell: Myth or Fact?

In the mechanical characterization of powders using the direct shear testers such as the Jenike shear cell, the existence of a uniform or well‐defined stress field in a powder specimen is assumed. This assumption has not been subjected to any serious scrutiny in the literature. In this study, the normal stress variation in a silica powder was locally determined by locating a pressure‐sensitive TekScan pad at the bottom section of a Jenike shear cell. A computer simulation of the consolidation and pre‐shearing stages of the Jenike test procedure was performed using the Discrete Element Method (DEM). The paper presents both experimental and computational evidence for the existence of a complex stress field in the powder specimen, thus clearly invalidating the long‐standing stress homogeneity assumption in the direct shear testing of powders. The implications of the stress inhomogeneity in terms of the accuracy of the material properties extracted from the Jenike test are also presented.     

Synthesis of new amphiphilic and lypophilic polymer networks containing 2‐methyl‐ and 2‐nonyl‐2‐oxazoline by the macroinitiator method

New amphiphilic and lypophilic polymer networks were obtained by the copolymerization of 2‐methyl‐2‐oxazoline (MeOXA), and/or 2‐nonyl‐2‐oxazoline (NoOXA) and 2,2′‐tetramethylenebis(2‐oxazoline) (BisOXA), respectively, initiating the copolymerization by random copolymers of chloromethylstyrene and methyl methacrylate or of chloromethylstyrene and styrene (macroinitiator method). Potassium iodide was used as an activator agent and the reaction was carried out in benzonitrile at 110 °C. In general, the polymer gels were obtained with a yield of 62 to 88%. The networks were characterized by high‐resolution magic angle spinning (HRMAS) NMR spectroscopy and by its absorption of polar and nonpolar solvents. In the case of amphiphilic polymer networks, the absorption of solvents depends on the molar ratio of 2‐methyl‐ to 2‐nonyl‐2‐oxazoline inside the polymer network favoring the absorption of polar solvents with a higher content of 2‐methyl‐2‐oxazoline. These gels showed a maximal swelling degree of 13 mL of water, 20 mL of methanol, and 13 mL of chloroform, respectively, per g of polymer. The lypophilic polymer networks containing only 2‐nonyl‐2‐oxazoline showed a maximal swelling degree of 8 mL of toluene, 14 mL of chloroform, and 2 mL of methanol, respectively, per g of the lypophilic network. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 122–128, 2005