Innovative determination of polar organophosphonate pesticides based on high‐resolution Orbitrap mass spectrometry

The determination of compounds showing a very low molecular weight (i.e. < 200 Da) can be complicated when low‐resolution mass spectrometry is used in the selected‐reaction monitoring mode, since the possible number of product ions is reduced and the obtained reactions are not selective enough to overcome background noise and/or matrix interferences. In this study, the use of high‐resolution mass spectrometry based on Exactive Orbitrap was applied for the determination of a group of polar organophosphonate pesticides and transformation products (TPs), which show the aforementioned features, in agricultural soils. Namely, glyphosate, glufosinate, ethephon and their TPs, aminomethyl phosphonic acid (AMPA), 3‐methylphosphinicopropionic acid, N‐acetyl‐glufosinate and 2‐hydroxyethylphosphonic acid were analyzed. The [M‐H]^‐ ions 168.00564, 180.04202, 142.96593, 110.00016, 151.01547, 222.05259 and 124.99982 were used, respectively, for the detection and identification of the compounds. Confirmation was carried out by using accurate mass measurements of ion fragments for each compound, from neutral losses of CO₂, H₂O and H₂CO (formaldehyde). Furthermore, the recently reported tool, relative isotopic mass defect (RΔm), was also used to support the confirmation protocol. The optimized method was fully validated at low levels, including the estimation of a not commonly used parameter: the limit of confirmation (LOC). This LOC is expressed as the lowest concentration of compound that can be confirmed using a fragment or the RΔm, and it ranged from 10 to 50 µg kg^?1 for all compounds. All the data was obtained in a single injection. Finally, the method was applied to real soil samples, and glyphosate and AMPA were found at 265 µg kg^?1 and 105 µg kg^?1, respectively. Copyright © 2012 John Wiley & Sons, Ltd.     

On the measurability of functions with quasi-continuous and upper semi-continuous vertical sections

Let f: ?² → ? be a function with upper semicontinuous and quasi-continuous vertical sections f _x (t) = f(x, t), t, x ∈ ?. It is proved that if the horizontal sections f ^y (t) = f(t, y), y, t ∈ ?, are of Baire class α (resp. Lebesgue measurable) [resp. with the Baire property] then f is of Baire class α + 2 (resp. Lebesgue measurable and sup-measurable) [resp. has Baire property].     

Covering functions by countably many functions from some families

Let $ \mathcal{A} $ be a nonempty family of functions from $ \mathbb{R} $ to $ \mathbb{R} $ . A function $ f:\mathbb{R}\to \mathbb{R} $ is said to be strongly countably $ \mathcal{A} $ -function if there is a sequence (f _n ) of functions from $ \mathcal{A} $ such that $ \mathrm{Gr}(f)\subset {\cup_n}\mathrm{Gr}\left( {{f_n}} \right) $ (Gr(f) denotes the graph of f). If $ \mathcal{A} $ is the family of all continuous functions, the strongly countable $ \mathcal{A} $ -functions are called strongly countably continuous and were investigated in [Z. Grande and A. Fatz-Grupka, On countably continuous functions, Tatra Mt. Math. Publ., 28:57–63, 2004], [G. Horbaczewska, On strongly countably continuous functions, Tatra Mt. Math. Publ., 42:81–86, 2009], and [T.A. Natkaniec, On additive countably continuous functions, Publ. Math., 79(1–2):1–6, 2011]. In this article, we prove that the families $ \mathcal{A}\left( \mathbb{R} \right) $ of all strongly countably $ \mathcal{A} $ -functions are closed with respect to some operations in dependence of analogous properties of the families $ \mathcal{A} $ , and, in particular, we show some properties of strongly countably differentiable functions, strongly countably approximately continuous functions, and strongly countably quasi-continuous functions.     

Beamforming with a circular microphone array for localization of environmental noise sources

It is often enough to localize environmental sources of noise from different directions in a plane. This can be accomplished with a circular microphone array, which can be designed to have practically the same resolution over 360°. The microphones can be suspended in free space or they can be mounted on a solid cylinder. This investigation examines and compares two techniques based on such arrays, the classical delay-and-sum beamforming and an alternative method called circular harmonics beamforming. The latter is based on decomposing the sound field into a series of circular harmonics. The performance of the two signal processing techniques is examined using computer simulations, and the results are validated experimentally.     

Toward the controlled production of oligoesters by microwave-assisted degradation of poly(3-hydroxyalkanoate)s

The degradation of poly(3-hydroxyalkanoate)s (PHAs) could be performed in a rapid, inexpensive and straightforward way via microwave irradiation with good potential for further scale-up. One such degradation was compared to that induced by conventional heating at 190 °C. The experimental results showed that PHA oligomers with varying molar masses, characterized by a terminal crotonic double bond and a carboxyl group on the other chain end, could be effectively obtained from native PHAs in the bulk by both degradation approaches. The kinetics of PHA oligomer production was monitored by size exclusion chromatography and ¹H NMR. The influence of temperature as well as microwave irradiation time and power was investigated, and the optimal conditions of degradation are described. It turned out that this treatment was much more efficient than a conventional thermally-induced degradation, as oligomers with similar molar masses were formed with an about 100 times faster rate corresponding to very short irradiation times (maximum 15 min). Two microwave-assisted procedures could be advantageously used: an irradiation with constant temperature was appropriate to afford PHA oligomers with molar masses lower than 1000 g.mol⁻¹ and high yields, while irradiation under constant power was more convenient to provide oligoesters with higher molar masses.     

Synthesis of polycyclic β-lactams. Evolution of tertiary radicals generated by Cp2TiCl from 1,5- and 1,6-epoxynitriles

Radical cyclisation induced by Cp₂TiCl of several 1,5- and 1,6-epoxynitriles derived from β-lactams gave 3-oxo-4-methyl-4-hydroxymethylcarbapenams or 4-oxo-5-methylbenzocarbacephems. Apart from these polycyclic β-lactams, the generated alkyl tertiary radicals also evolved to enamides through β-fragmentation and reduction and the tertiary homobenzyl radicals gave a 3,4-trans-6-hydroxymonolactam by hydrogen transfer.     

Novel Functional Mesoporous Materials Obtained from Nanostructured Diblock Copolymers

Summary: Novel carboxy (COOH)-functionalized mesoporous polystyrene membranes were prepared from polystyrene-block-poly(D,L-lactide) (PS-b-PLA) diblock copolymers through the selective degradation of the PLA block. The combination of atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP) techniques enabled the synthesis of nanostructured diblock copolymers possessing carboxylic acid functionality at the junction between both blocks. Such copolymers were subjected to shear flow through the use of a channel die to align their nanodomains. Under mild alkaline conditions, the quantitative hydrolysis of the polyester nanodomains afforded mesoporous materials with COOH-coated pore walls. The PS-b-PLA precursors as well as the resulting porous systems were carefully analyzed by size exclusion chromatography (SEC), ¹H NMR, scanning electron microscopy (SEM), and two-dimensional small-angle X-ray scattering (2-D SAXS). Moreover, the specific surface area and pore size distribution were determined by nitrogen sorption porosimetry.     

Nuclear spin—lattice relaxation and molecular motions in the thermotropic mesophases of p-alkoxybenzylidene—p-n-alkylanilines

Experimental results of an investigation of the proton spin—lattice relaxation in a well-known homologous series exhibiting smectic polymorphism, are presented. Explanations for striking features of T₁ and T_1D dependences on temperature, frequency and molecular orientation in terms of molecular motions are proposed.     

Enthalpies of Formation of La1−xAxMnO3±δ (A=Ca and Sr) Measured by High-Temperature Solution Calorimetry

High-temperature reaction calorimetry using molten lead borate as a solvent has been used to study the thermochemistry of La_1−xA_xMnO₃ (A=Ca and Sr, 0≤x≤1). The structural properties and the oxygen stoichiometry of the calcined powders were characterized by powder X-ray diffraction, thermogravimetry, and iodometry. The enthalpy of formation of the materials from their binary constituents has been calculated from measured enthalpy of solutions. The enthalpy of formation of La_1−xCa_xMnO₃ from the component oxides becomes more exothermic with increasing substitution level x due to the increasing valence state of Mn, and demonstrates a nearly linear dependence of the average valence state of manganese. La_1−xSr_xMnO₃ has a significantly more exothermic enthalpy of formation from the binary constituents than the Ca-substituted materials, and demonstrates a negative deviation from ideal behavior. The present thermodynamic data are discussed in relation to the Goldschmidt tolerance factor for the perovskite structure. Finally, the phase stability of Sr- and Ca-substituted LaMnO₃ is addressed in relation to the application of these materials in solid oxide fuel cells.     

Metal complexes of anxiolitic drugs. Crystal structure and electronic properties of dimeric oxalato complex of copper(II) bromazepam

Summary The title compound, has been prepared; its crystal structure, solved at room temperature, consists of dimer units bridged by oxalate lignads. Each copper ion is surrounded by two nitrogens of bromazepam and two oxygens of the oxalate ligand; a molecule of water occupies the apical site. The magnetic properties of the title compound have been investigated in the 30–300 K range. The molar magnetic susceptibility closely follows the behaviour expected for an antiferromagnetically coupled copper(II) binuclear complex with a singlet-triplet energy gap,J=–349 cm^–1.