Magnetite, a model system for mixed-valence oxides, does not show charge ordering

We have investigated the charge ordering (CO) in magnetite below the Verwey transition. A new set of half-integer and mixed-integer superlattice reflections of the low-temperature phase have been studied by x-ray resonant scattering. None of these reflections show features characteristic of CO. We demonstrate the absence of CO along the c axis with the periodicity of either the cubic lattice q=(001) or the doubled cubic lattice q=(001/2). This result suggests that the Verwey transition is caused by strong electron-phonon interaction instead of an electronic ordering on the octahedral Fe atoms.     

Development of a laser photothermoacoustic frequency-swept system for subsurface imaging: theory and experiment

In conventional biomedical photoacoustic imaging systems, a pulsed laser is used to generate time-of-flight acoustic information of the subsurface features. This paper reports the theoretical and experimental development of a new frequency-domain (FD) photo-thermo-acoustic (PTA) principle featuring frequency sweep (chirp) and heterodyne modulation and lock-in detection of a continuous-wave laser source at 1064 nm wavelength. PTA imaging is a promising new technique which is being developed to detect tumor masses in turbid biological tissue. Owing to the linear relationship between the depth of acoustic signal generation and the delay time of signal arrival to the transducer, information specific to a particular depth can be associated with a particular frequency in the chirp signal. Scanning laser modulation with a linear frequency sweep method preserves the depth-to-delay time linearity and recovers FD-PTA signals from a range of depths. Preliminary results performed on rubber samples and solid tissue phantoms indicate that the FD-PTA technique has the potential to be a reliable tool for biomedical depth-profilometric imaging.     

A solid-phase approach towards the development of 3-aza-6,8-dioxabicyclo[3.2.1]octane scaffolds

The development of new strategies for solid-phase synthesis of 3-aza-6,8-dioxabicyclo[3.2.1]octane scaffolds, named BTKa, is described. The preparation was made possible by the combination of three components: amines, alpha-halo-acetophenones, and sugar or tartaric acid derivatives. By anchoring each of the three components it was possible to synthesize BTKa compounds either as amino alcohols or amido esters. The compatibility of the protocols with different classes of amines and substituted alpha-halo-acetophenones was demonstrated.     

Experimental observation of the alpha relaxation in supercooled water

Intermediate scattering functions for density fluctuation in D2O contained in pores of a Vycor glass have been measured using an improved neutron spin-echo spectrometer at two supercooled temperatures. The measurements cover the time range from 1 to 2300 ps with the Q range spanning the first diffraction peak of water. The time correlation functions can be fitted to a stretched exponential relaxation function with a Q-dependent amplitude. Both the stretch exponent and the relaxation time peak approximately at the Q value corresponding to the first diffraction peak, confirming the validity of the mode coupling idea in supercooled water.     

Ugi four-component condensation with two cleavable components: the easiest synthesis of 2,N-diarylglycines

The Ugi four-component condensation between anilines, aromatic aldehydes, isocyanides, and α-oxoacids afforded the expected adducts which were cleaved in mild conditions to give 2,N-diarylglycines in high yields.     

Cosmic-muon results from the NUSEX experiment

Summary Muon underground data collected in the NUSEX experiment at Mont Blanc have been analysed concerning the following topics: I) vertical muon intensity, II) prompt muon flux, III) muons from the direction of Cygnus X-3. Preliminary results from the analysis of more than 20 000 muons are presented and discussed.

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Riassunto Gli eventi di muoni rivelati sottoterra nell'esperimento NUSEX al Monte Bianco sono stati analizzati per studiare I) l'intensità verticale dei muoni, II) il flusso di muoni pronti, III) l'eccesso di muoni dalla direzione di Cygnus X-3. In questo lavoro sono presentati c discussi i risultati preliminari ottenuti dal'lanalisi di piú di 20.000 eventi.

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Резюме Был проведен анализ данных, собранных в экспеимемнте NUSEX на Мон Блане. Анализировались следующие вопросы: 1) интенсивность вертикальных мюонов, 2) поток мгновенных (быстрых) мюонов, 3) мюоны, движущиеся в направлении от Лебедь X-3. Приводятся и обсуждаются предварительные результаты анализа для более, чем 20 000 муонов.

     

Gas-chromatography–mass spectrometry analysis of dimethyl fumarate in consumer products

Two methods for the analysis of dimethyl fumarate (DMF) on silica gel, leather and other similar products are presented. The methods are based on solvent extraction or head space solid phase microextraction coupled with gas-chromatography–mass spectrometry. The methods are developed in order to satisfy the mandatory requirements of the European Community and with the aim to have easy and reliable methods to provide rapid responses.     

A Survey of Calculator Usage in High Schools

This survey investigated the current status of calculator use in classrooms and schools. The results indicated that the prevailing policy in the sample of high schools is to allow the use of calculators during classroom learning activities and tests. Scientific calculators are more frequently used than graphing calculators in algebra I and geometry; whereas, graphing calculators are more frequently used in algebra II and precalculus/trigonometry. At the time of this survey, school policies regarding the use of graphing calculators with symbolic algebra capabilities were still not determined.     

Future teachers’ professional knowledge on argumentation and proof: a case study from universities in three countries

In this paper, qualitative results of a case study about the professional knowledge in the area of argumentation and proof of future teachers from universities in three countries are described. Based on results of open questionnaires, data about the competencies these future teachers have in the areas of mathematical knowledge and knowledge of mathematics pedagogy are presented. The study shows that the majority of the future teachers at the participating universities situated in Germany, Hong Kong and Australia, were not able to execute formal proofs, requiring only lower secondary mathematical content, in an adequate and mathematically correct way. In contrast, in all samples there was evidence of at least average competencies of pedagogical content reflection about formal and pre-formal proving in mathematics teaching. However, it appears that possessing a mathematical background as mandated for teaching and having a high affinity with proving in mathematics teaching at the lower secondary level are not a sufficient preparation for teaching proof.     

An alternative approach toward 2-aryl-2H-pyrazolo[4,3-c]-quinolin-3-ones by a multistep synthesis

A series of 2-aryl-2H-pyrazolo[4,3-c]quinolin-3-ones derivatives 6 and 7 was conveniently prepared. A multistep synthesis was carried out starting from dichloro- and bromoanilines (1a-b) and diethyl 2-(ethoxymethylene)malonate using a slightly modified Gould-Jacobs reaction. In this work we present a novel chlorination strategy to prepare quinoline derivatives 4 in excellent yields as key intermediates in the synthesis of the target compounds. Several reaction conditions were evaluated to optimize the formation of pyrazoloquinolinone nucleus. Differences in chemical behavior of both chloroquinolinones 4a-b with aryl and benzyl-hydrazines are also discussed.