Removal of chlorinated solvents from carbonate-buffered water by zero-valent iron

The performance of a ground level reactive cell, filled with Fe⁰, designed for the treatment of water contaminated by chlorinated solvents, having a total input concentration of approximately 2 mg 1⁻¹ of the principal contaminants trichloroethene and perchloroethene, was tested at the Milovice site in the Czech Republic. A residence time of 1.62 days in the box was sufficient to reduce concentrations to a fraction less than 0.015 of the initial concentration. However, incomplete degradation of cis-1,2-DCE was observed. Reactions approximated first-order kinetics. The principal changes of concentrations of inorganic dissolved species in the reactive cell occurred for Ca²⁺, HCO ₃ ⁻ , NO ₃ ⁻ (decreased) and for Fe (initially increased, then decreased). Changes for Ca²⁺ and HCO ₃ ⁻ were caused by the precipitation of secondary carbonate mineral phases such as aragonite and siderite with the minor presence of green rust-CO₃. Concentration changes were gradual, along the complete length of the cell with a maximum at the inlet zone. The observations were attributed to minor increases of pH and slow kinetics of precipitation in the carbonate-buffered system. The average porosity loss was estimated to be approximately 2.7 % of the initial porosity per year, suggesting the long-term function of the permeable reactive barrier.      

Detecting cross talk between two halves of a phospholipid bilayer

One of the most challenging questions that relates to the structure and function of biological membranes is whether the two halves of the bilayer "talk" to each other. In this letter, we show how the perturbation of the lateral organization of one leaflet of a fluid phospholipid bilayer by an external agent also alters the lateral organization of the adjoining leaflet. In addition, we show that the energy involved in such "cross talk" corresponds to ca. 100 cal/mol of phospholipid. These findings provide a basis for expecting similar cross talk to exist in cell membranes.     

Ion mobility-mass spectrometry

This review article compares and contrasts various types of ion mobility-mass spectrometers available today and describes their advantages for application to a wide range of analytes. Ion mobility spectrometry (IMS), when coupled with mass spectrometry, offers value-added data not possible from mass spectra alone. Separation of isomers, isobars, and conformers; reduction of chemical noise; and measurement of ion size are possible with the addition of ion mobility cells to mass spectrometers. In addition, structurally similar ions and ions of the same charge state can be separated into families of ions which appear along a unique mass-mobility correlation line. This review describes the four methods of ion mobility separation currently used with mass spectrometry. They are (1) drift-time ion mobility spectrometry (DTIMS), (2) aspiration ion mobility spectrometry (AIMS), (3) differential-mobility spectrometry (DMS) which is also called field-asymmetric waveform ion mobility spectrometry (FAIMS) and (4) traveling-wave ion mobility spectrometry (TWIMS). DTIMS provides the highest IMS resolving power and is the only IMS method which can directly measure collision cross-sections. AIMS is a low resolution mobility separation method but can monitor ions in a continuous manner. DMS and FAIMS offer continuous-ion monitoring capability as well as orthogonal ion mobility separation in which high-separation selectivity can be achieved. TWIMS is a novel method of IMS with a low resolving power but has good sensitivity and is well intergrated into a commercial mass spectrometer. One hundred and sixty references on ion mobility-mass spectrometry (IMMS) are provided.     

Crab-Eating Monkey Acidic Chitinase (CHIA) Efficiently Degrades Chitin and Chitosan under Acidic and High-Temperature Conditions

Chitooligosaccharides, the degradation products of chitin and chitosan, possess anti-bacterial, anti-tumor, and anti-inflammatory activities. The enzymatic production of chitooligosaccharides may increase the interest in their potential biomedical or agricultural usability in terms of the safety and simplicity of the manufacturing process. Crab-eating monkey acidic chitinase (CHIA) is an enzyme with robust activity in various environments. Here, we report the efficient degradation of chitin and chitosan by monkey CHIA under acidic and high-temperature conditions. Monkey CHIA hydrolyzed α-chitin at 50 °C, producing N-acetyl-d-glucosamine (GlcNAc) dimers more efficiently than at 37 °C. Moreover, the degradation rate increased with a longer incubation time (up to 72 h) without the inactivation of the enzyme. Five substrates (α-chitin, colloidal chitin, P-chitin, block-type, and random-type chitosan substrates) were exposed to monkey CHIS at pH 2.0 or pH 5.0 at 50 °C. P-chitin and random-type chitosan appeared to be the best sources of GlcNAc dimers and broad-scale chitooligosaccharides, respectively. In addition, the pattern of the products from the block-type chitosan was different between pH conditions (pH 2.0 and pH 5.0). Thus, monkey CHIA can degrade chitin and chitosan efficiently without inactivation under high-temperature or low pH conditions. Our results show that certain chitooligosaccharides are enriched by using different substrates under different conditions. Therefore, the reaction conditions can be adjusted to obtain desired oligomers. Crab-eating monkey CHIA can potentially become an efficient tool in producing chitooligosaccharide sets for agricultural and biomedical purposes.     

Ultrasonic synthesis,crystal structure,luminescent, and magnetic properties of a new metal–organic complex based on Ce(IV)–Sr(II)

Research on Chemical Intermediates - This paper presents the sonochemical synthesis of a new hetero-metallic inorganic complex, formulated as [(Sr(OH2)5Ce(dipic)3Sr(OH2)6][Ce(dipic)3]·6H2O...     

Determination of Plant Thiols by Liquid Chromatography Coupled with Coulometric and Amperometric Detection in Lettuce Treated by Lead(II) Ions

The main aim of this paper is to utilize high performance liquid chromatography with electrochemical detection for determination of thiols content in plants tissues of lettuce treated with lead(II) ions (0, 0.5 and 1 mM). We used two HPLC‐ED instruments: HPLC coupled with one channel amperometric detector and HPLC coupled with twelve channel coulometric detector to detect simultaneously twelve thiols. The detection limits of thiols measured by CoulArray detector were about two magnitudes lower in comparison to those measured by Coulochem III detector and were from tens to hundreds pM. Under the optimal conditions, we utilized HPLC‐CoulArray detector for analysis of tissues from lettuce plants. In addition, distribution and accumulation of lead ions with high spatial resolution was monitored using laser induced breakdown spectroscopy.     

Gluing Langmuir-Blodgett monolayers onto hydrocarbon surfaces

This paper describes a new approach for modifying hydrophobic surfaces that is based on the use of ionically cross-linked (i.e., "glued") Langmuir-Blodgett monolayers. Specifically, this work shows how monolayers of 5,11,17,23,29,35-hexa(trimethylammonium methyl)-37,38,39,40,41,42-hexakis-n-hexadecyloxy-calix[6]arene (1a), which have been ionically cross-linked with poly(4-styrene-sulfonate) (PSS, MW 30,000-50,000), can be deposited onto silylated silicon wafers with their polar headgroups extending outward into air. This work also demonstrates the feasibility of using glued monolayers of 1a as "anchors" for attaching alternating layers of poly(diallyldimethylammonium) [PDADMA] and PSS ions onto these same hydrocarbon surfaces.     

Cubic octanuclear aluminum fluoride phosphonate

A crystalline complex [Al8F12{(CH3)2C(NH3)PO3}12] (1) was isolated from the supernatant of the hydrothermal reaction of gibbsite Al(OH)3 with 1-amino-1-methyl-ethylphosphonic acid (AIPA) and the HF mineralizer. The single-crystal X-ray diffraction analysis revealed a highly symmetrical cubic Al8F12 core with aluminum atoms at the corners, bridging fluorides spanning all edges, and 12 bidentate bridging phosphonate ligands completing the octahedral coordination sphere of aluminum centers. The stability of the complex in solution was established by electrospray mass spectrometry and the high molecular symmetry (Th) was reflected in the appearance of single resonances in the 1H, 19F, and 31P NMR spectra.     

Lateral Vortex Dynamics behind Ahmed body

The flow-field in the wake of Ahmed body was studied experimentally. The study is oriented on unsteady behavior of the lateral vortex pair arising in the wake as well as on the wake itself. The time-mean characteristics of the wake flow are presented. The dynamical behavior of the longitudinal vortex pair is studied in details. The Stereo Time-Resolved PIV method was applied in the wake plane perpendicular to the mean flow. Two variants of Ahmed Body with slat angle 25 and 35 degrees are investigated respectively. Comparison shows considerable differences in the vortex pair topology and dynamics of the cases in question. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Quantification of purine basis in their mixtures at femto‐molar concentration levels using FT‐SERS

Surface‐enhanced Raman scattering spectroscopy represents one of the unique techniques for studying nanoscale objects, and its distinctive properties can be used in the process of further analysis. The careful evaluation of the particular influence of selected key‐role experimental parameters (e.g. pH value of measured sample mixture, size and distribution of used nanoparticles) and the influence of reduction agent used in the process of formation of desired nanoparticle objects presents an important task in the further study of surface‐enhanced Raman scattering effect. A broad study of these experimental parameters was performed in this paper. The main aim of the presented work was to a demonstrate an application potential of selected experimental conditions in the determination of three purine bases: adenine, xanthine, and hypoxanthine. The resulting limits of detection are at femtomolar concentration levels for all three studied compounds. Copyright © 2011 John Wiley & Sons, Ltd.