4-(2-Hydroxyaryl)-1,2,3-thiadiazoles as a Source of 2-Benzofuranthiolates

Following the Hurd-Mori procedure, 4-(2-hydroxyaryl)-1,2,3-thiadiazoles were synthesized from o-hydroxyacetophenones. Treatment of the products with bases gives 2-benzofuranthiolates which can be involved in alkylation and arylation reactions.     

Electron transition in intercalated disulfide CuCrS<Subscript>2</Subscript>

Electrical, resonant, and magnetic properties of intercalated copper chromium disulfide CuCrS₂ are studied. It is established that CuCrS₂ is an antiferromagnetic semiconductor with Néel temperature T_N=40.7 K and an effective magnetic moment of 4.3µ_B. Anomalies in the electrical, magnetic, and resonant properties of CuCrS₂ are found at T_c=110 K, which suggest an electron transition accompanied by alteration of the valences of the 3d-metal ions.     

Carbon nanotube "T Junctions": formation pathways and conductivity

Using tight-binding molecular dynamics we simulate the formation of single wall carbon nanotube T junctions via the fusing of two nanotubes. We propose energetically efficient pathways for this process in which all atoms maintain their sp(2) arrangements throughout. Recent experimental advances have greatly increased the plausibility of synthesizing T junctions as proposed in the simulations. We further report I-V characteristics of the formed junctions.     

A new method for [c,d]pyridine peri-annelation: synthesis of azapyrenes from phenalenes and their dihydro derivatives

An effective synthesis of various azapyrenes from phenalenes and their dihydro derivatives has been developed using 1,3,5-triazines in polyphosphoric acid (PPA).     

Phosphoric acid cation exchanger based on immobilized <Emphasis Type="Italic">cis</Emphasis>-calix[4]resorcinolarene

New phosphoric acid cation exchanger was synthesized on the basis of immobilized calix[4] resorcinolarene and its service characteristics were determined.     

Macroion effective charge in complex plasmas with regard to microion correlations

In the present paper, features of high-charged macroions screening by microions are analysed in classical asymmetrically charged complex plasmas. We consider a two-component electroneutral system of classical macroions and oppositely charged microions in a spherically symmetrical electroneutral Wigner–Seitz cell with a central macroion in its centre. The present paper is devoted to a problem of a relation between the effective macroion charge and an initial one with regard to a non-linear screening effect and microions correlations. We show how this relation changes with the number of the central macroion charge value on the rise. Characteristics of two different parts of the relation between the effective charge and the initial one are calculated.     

GC–MS Studies of Thiophenes in the Supercritical Fluid CO2 and Solvent Extracts of Tagetes patula L.

The intact plant parts and genetically modified hairy root clone #TpA6 of Tagetes patula were extracted with supercritical fluid CO₂ extraction (SFE) and a conventional solvent extraction. SFE optimization included the variation of fluid CO₂ pressure, dynamic time, and the addition of methanol modifier co-solvent. The four characteristic thiophene metabolites, 5-(3-buten-1-ynyl)-2,2′-bithienyl (BBT), 2,2′:5′,2″-terthiophene (α-T), 5-(4-acetoxy-1-butynyl)-2,2′-bithienyl (BBTOAc), and 5-(3,4-diacetoxy-1-butynyl)-2,2′-bithienyl [BBT(OAc)₂], were analysed by GC–MS. The proposed SFE method allowed the selective extraction of thiophenes in 60 min dynamic time with supercritical CO₂ without modifier co-solvent, at 30 MPa and 40 °C. The SFE and the reference solvent extraction yielded similar results. The SFE of intact roots and flowers yielded 717 ± 31.3 and 480 ± 26.6 μg g^?1 α-T, respectively, while the leaves did not contain considerable amounts of thiophenes. Remarkable amounts of BBT, BBTOAc, and BBT(OAc)₂ were characteristic of the SFE of hairy root cultures.     

Heat capacity and thermal conductivity of Fe x Mn1 − x S single crystals

This paper reports on the results of investigations of the thermal properties and thermal conductivity of single crystals of homogeneous solid solutions Fe _x Mn_{1 ? x} S with a cubic NaCl structure, which have been prepared by the cation substitution for divalent manganese ions in manganese monosulfide. It has been revealed that the heat capacity and thermal conductivity exhibit anomalies in the range of the magnetic transition. The cation substitution is accompanied by an increase in the phase transition temperature.     

Towards a full reference library of MS(n) spectra. II: A perspective from the library of pesticide spectra extracted from the literature/Internet

To gain perspective on building full transferable libraries of MS(n) spectra from their diverse/numerous collections, a new library was built from 1723 MS(>1) spectra (mainly MS2 spectra) of 490 pesticides and related compounds. Spectra acquired on different types of tandem instruments in various experimental conditions were extracted from 168 literature articles and Internet sites. Testing of the library was based on searches where 'unknown' and reference spectra originated from different sources (mainly from different laboratories) were cross-compared. The NIST 05 MS2 library was added to the reference spectra. The library searches were performed with all the test spectra or were divided into different subsamples containing (a) various numbers of replicate spectra of test compounds or (b) spectra acquired from different instrument types. Thus, the dependence of true/false search (identification) result rates on different factors was explored. The percentage of 1st rank correct identifications (true positives) for the only 'unknown' mass spectrum and two and more reference spectra and matching precursor ion m/z values was 89%. For qualified matches, above the cut-off match factor, that rate decreased to 80%. The corresponding rates based on the best match for two and more 'unknown' and reference spectral replicates were 89-94%. For quadrupole instruments, the rates were even higher: 91-95% (one 'unknown' spectrum) and 90-100% (two and more such spectra). This study shows that MS2 spectral libraries generated from the numerous literature/Internet sources are not less efficient for the goal of identification of unknown compounds including pesticides than very common EI-MS1 libraries and are almost as efficient as the most productive from current MS2 spectral databases. Such libraries may be used as individual reference databases or supplements to large experimental spectral collections covering many groups of abundant compounds and different types of tandem mass spectrometers.     

Magnetic resonance in a Cu-Cr-S structure

A layered Cu-Cr-S structure composed of single-crystal CuCrS₂ layers and thin CuCr₂S₄ plates embedded in them has been investigated by the magnetic resonance and scanning electron microscopy methods. The Curie temperature and saturation magnetization of the spinel phase of the investigated samples have been determined. The thickness of the CuCr₂S₄ layers has been estimated. The dependence of the growncrystal topology on synthesis conditions has been established. An interpretation of the anomalous behavior of the magnetostatic oscillation intensity is offered.