Anion exchange fibers for arsenate removal derived from a vinylbenzyl chloride precursor

The preparation of anionic exchange fibers (AEFs) is described utilizing an oligomer derived from vinylbenzyl chloride as the precursor coating on a glass fiber substrate. This approach permits a significant reduction in number of synthetic steps required for commercial beads, as well as eliminating the need for solvents prior to functionalization. The amination reaction time was also substantially reduced. These fibers were characterized through a variety of techniques such as scanning electron microscopy (SEM), analytical titration, and diffuse reflectance fourier transform infrared spectroscopy (DRIFTS) of the copolymer. With respect to ion exchange properties the fibers could be regenerated for over 20 cycles with no capacity loss or physical degradation of the coating. Particular emphasis was placed on establishing conditions for the removal of arsenate from water. The design and testing of AEF filters for breakthrough experiments were carried out and compared to commercially available beads. The results indicate that AEF have a significant kinetic advantage over the anionic exchange beads, which approaches an order of magnitude improvement in lowering effluent contaminants. Copyright © 2003 John Wiley & Sons, Ltd.     

GridMass: a fast two‐dimensional feature detection method for LC/MS

One of the initial and critical procedures for the analysis of metabolomics data using liquid chromatography and mass spectrometry is feature detection. Feature detection is the process to detect boundaries of the mass surface from raw data. It consists of detected abundances arranged in a two‐dimensional (2D) matrix of mass/charge and elution time. MZmine 2 is one of the leading software environments that provide a full analysis pipeline for these data. However, the feature detection algorithms provided in MZmine 2 are based mainly on the analysis of one‐dimension at a time. We propose GridMass, an efficient algorithm for 2D feature detection. The algorithm is based on landing probes across the chromatographic space that are moved to find local maxima providing accurate boundary estimations. We tested GridMass on a controlled marker experiment, on plasma samples, on plant fruits, and in a proteome sample. Compared with other algorithms, GridMass is faster and may achieve comparable or better sensitivity and specificity. As a proof of concept, GridMass has been implemented in Java under the MZmine 2 environment and is available at http://bioinformatica.mty.itesm.mx/GridMass and MASSyPup. It has also been submitted to the MZmine 2 developing community. Copyright © 2015 John Wiley & Sons, Ltd.     

Generic Picard–Vessiot Extensions for Nonconnected Groups

Let K be a differential field with algebraically closed field of constants 𝒞 and G a linear algebraic group over 𝒞. We provide a characterization of the K-irreducible G-torsors for nonconnected groups G in terms of the first Galois cohomology H¹(K, G) and use it to construct Picard–Vessiot extensions which correspond to nontrivial torsors for the infinite quaternion group, the infinite multiplicative and additive dihedral groups and the orthogonal groups. The extensions so constructed are generic for those groups.     

Enhancement of wettability in low density polyethylene films using low pressure glow discharge N2 plasma

Low pressure glow discharge nitrogen plasma has been used to improve wettability in a low density polyethylene (LDPE) film for technical applications. The plasma treatment was carried out at a power of 300 W for different exposure times in the 1–20 min range. Wettability changes were analyzed using contact angle measurements. In addition to this, plasma‐treated samples were subjected to an aging process to determine the durability of the plasma treatment. X‐ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy were used for surface characterization. The nitrogen plasma treatment considerably reduced contact angle values thus indicating an increase in surface wettability. The spectroscopic study showed presence of oxygen‐based species on the plasma‐treated samples, which are mainly generated after the plasma treatment as a consequence of air exposure. These polar species contribute to improve surface functionalization, but this is almost lost during aging due to the hydrophobic recovery process. Microscopic studies revealed that also small changes in surface roughness occurred during the plasma treatment but these are very low compared to surface activation. The results confirmed that low pressure nitrogen can be considered as an environmentally efficient process to improve wettability in low density polyethylene films. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2390–2399, 2007     

Uranium determination at ppb levels by X-ray fluorescence after its preconcentration on polyurethane foam

A sensitive method based on the preconcentration of uranium on powdered polyurethane foam (PUF) has been developed to determinate this element in water samples by X-ray florescence. Uranium at ppb levels was sorbed as the salicylate complex on powdered PUF at pH 4.0. The resulting PUF was filtered through a filter paper and used for X-ray fluorescence measurements. For 50 μg/l of uranium the coefficient of variation for five measurements is 5% and the detection limit is 5.5 μg/l. The interference level of various ions and ligands was studied and optimum conditions were developed to determine uranium in reference materials, waste water, mine drainage, and sea water.     

Synthesis and characterization of some coumarins with two hydroxy or methoxy substituents

The first synthesis of the 6‐hydroxy‐4‐methoxycoumarin ( 5 ) was carried out in 25 % overall yield from 6‐methoxy‐4‐hydroxycoumarin ( 1 ) by hydrolysis of the methoxy group and subsequent selective methylation of the hydroxyl group at position 4. The ¹H and ¹³C NMR data of compounds 1–6 are reported.     

Composition and deployment of e-Health services over Wireless Sensor Networks

Providing necessary background for provisioning of a new generation of enriched services over Wireless Sensor Networks is the main effort that the scientific community is currently carrying out. These services have improved a great number of aspects related to pervasive systems such as saving resources, efficiency, reliability, scalability and low power consumption. In this paper, $\mu$SMS middleware, using an event-based service model, is presented. This novel approach makes up the design requirements previously mentioned by implementing a dynamic memory kernel and a variable payload multiplexing mechanism for the information events in order to provide advanced services. The results obtained over real-world deployments, especially those related with provision of e-Health services, reflect a significant improvement over other similar proposals, such as the RUNES approach: 50% lower memory overhead, 53% lower software components load time and 12% lower event’s propagation time.     

Fractional Square Functions and Potential Spaces, Ⅱ

In this paper, we study fractional square functions associated with the Poisson semigroup for Schrdinger operators. We characterize the potential spaces in the Schrdinger setting by using vertical, area and g*λ fractional square functions.