Adsorption of naphthalene and pyrene from isooctane solutions on commercial activated carbons

The adsorption of naphthalene and pyrene on two different types of commercial activated carbons was studied by batch and column experiments. Adsorption equilibrium was measured at three different temperatures. Heats of adsorption were estimated from the equilibrium results and compared to other previous reports. From the column experiments, using parameters obtained from the batch experiments and literature correlations, effective surface diffusivities were estimated for naphthalene and pyrene on both adsorbents in different feed concentrations. The corrected diffusivities, using Darken equation, appear to be almost constant for naphthalene (ca. 1.3⋅10⁻⁸ cm²/min), and for pyrene (ca. 2.3⋅10⁻¹⁰ cm²/min), in both activated carbons.     

Astrophysics from data analysis of spherical gravitational wave detectors

The direct detection of gravitational waves will provide valuable astrophysical information about many celestial objects. Also, it will be an important test to general relativity and other theories of gravitation. The gravitational wave detector SCHENBERG has recently undergone its first test run. It is expected to have its first scientific run soon. In this work the data analysis system of this spherical, resonant mass detector is tested through the simulation of the detection of gravitational waves generated during the inspiralling phase of a binary system. It is shown from the simulated data that it is not necessary to have all six transducers operational in order to determine the source’s direction and the wave’s amplitudes.     

Magnetic hyperfine field at Cr site in AgCrO2 given by Perturbed angular correlations

This work presents an electric field gradient and magnetic hyperfine field study, in the AgCrO₂ multiferroic with triangular spin lattice. The temperature dependence of the electric field gradient (efg) and magnetic hyperfine field (mhf) at Cr site was studied at isolde via perturbed angular correlation measurements with the ¹¹¹In probe, at room temperature and below the Néel temperature (T?≤?21 K) down to 12 K. The results show the presence of two distinct local environments. One axial symmetric efg with a very low mhf, and a non axially symmetric efg with a much higher one. The temperature dependences of mhf magnitude and of the angle between the mhf and the principle component of the efg are investigated.     

Structural and magnetic characterization of LaSrMnO3 thin films deposited by laser ablation on MgO substrates

La_2/3Sr_1/3MnO_3?δ thin films were deposited by laser ablation on MgO substrates under low oxygen pressure cool down. Their structural and magnetic properties are presented. The magnetic and electrical resistivity measurements indicate a reduction of the Curie and the metal–insulator transition temperatures due to the formation of magnetic inhomogeneneous films, where clusters of a metallic phase are mixed in a magnetically disordered insulating matrix. By a low-angle X-ray reflectivity study we show that the thin films are chemically inhomogeneous with an oxygen deficiency in bulk of the film when compared with the film/air interfacial region.     

Utilization of nondestructive techniques for analysis of the Martian meteorite NWA 6963 and its implications for astrobiology

Martian meteorites are excellent study materials for understanding the present and past of Mars, as they are important historical astrophysical artifacts because they possess information about Martian geological evolution and physical and chemical characteristics. In our case, we analyzed the NWA 6963 Martian meteorite classified as basaltic shergottite because of its chemical structure. A computerized microtomography (μCT) study in the NWA 6963 Martian meteorite provided us with 2D and 3D images that were extremely useful for ascertaining the internal structure of the analyzed sample and gave us the opportunity to find a crumpled material with a very peculiar structural format. In addition, it was possible to observe through the μCT that this encrusted material also has a completely different density of the meteorite. Calcium, strontium, and potassium were detected qualitatively, among others through the technique of X‐ray fluorescence.     

Tuning Local Coordination Environments of Manganese Single-Atom Nanozymes with Multi-Enzyme Properties for Selective Colorimetric Biosensing

Single-atom nanozymes (SAzymes) are promising in next-generation nanozymes, nevertheless, how to rationally modulate the microenvironment of SAzymes with controllable multi-enzyme properties is still challenging. Herein, we systematically investigate the relationship between atomic configuration and multi-enzymatic performances. The constructed Mn_SA−N₃-coordinated SAzymes (Mn_SA−N₃−C) exhibits much more remarkable oxidase-, peroxidase-, and glutathione oxidase-like activities than that of Mn_SA−N₄−C. Based on experimental and theoretical results, these multi-enzyme-like behaviors are highly dependent on the coordination number of single atomic Mn sites by local charge polarization. As a consequence, a series of colorimetric biosensing platforms based on Mn_SA−N₃−C SAzymes is successfully built for specific recognition of biological molecules. These findings provide atomic-level insight into the microenvironment of nanozymes, promoting rational design of other demanding biocatalysts.     

Microwave-assisted synthesis of 2-amino and 2-azetidinonyl 5-(2-benzoyl-phenoxymethyl) 1,3,4-oxadiazoles

A simple high yielding method for the integration of heterocyclic rings viz. 1,3,4-oxadiazole and azetidin-2-one at the benzophenone nucleus has been developed starting from substituted 2-hydroxybenzophenones, and by using mild conditions, wet solid surface, and microwave irradiation. A comparison of this microwave-accelerated reaction with conventional heating condition is also illustrated. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 15:37–42, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10210     

Comparing near infrared and Raman spectroscopy for on-line monitoring of emulsion copolymerization reactions

In this work, Raman and Near InfraRed (NIR) spectroscopies are evaluated for the monitoring of different semicontinuous emulsion homo- and co-polymerization reactions. Important process variables, namely monomer concentrations and average particle sizes, were monitored by both techniques under realistic conditions that would be found in an industrial environment (e.g. low signal/noise ratio, probe placed in the reaction medium). Results suggest that Raman and NIR are suitable for on-line monitoring of emulsion polymerization reactions and that the success of their application is mainly related to representative calibration models used for the estimation of the properties of interest.