11B MAS NMR spectroscopic study of structural relaxation, aging, and memory effect at the atomic scale in a borosilicate glass

Relaxation kinetics of boron coordination environments in a borosilicate glass in response to temperature jumps has been monitored using (11)B magic-angle spinning (MAS) NMR spectroscopy. The relaxation time scale of the BO4/BO3 ratio is found to be closely comparable with those of the bulk properties, namely, refractive index and viscosity, showing a close connection with one another. Samples partially equilibrated at a low temperature, when subjected to a positive temperature jump, display an initial rapid decrease followed by an increase in the BO4/BO3 ratio. This reversal in the trend of the variation of the BO4/BO3 ratio has been interpreted to be the signature of a memory effect, and the implications are discussed within the framework of the potential energy landscape model of glassy dynamics.     

Radiation induced in-situ generation of conductivity in the blends of polyaniline-base with chlorinated-polyisoprene

Radiation induced acid doping of PANI to generate electrical conductivity was achieved by radiation induced HCl release from chlorinated-polyisoprene (ClPIP). Blends of PANI with ClPIP were prepared by mechanical mixing/grinding in the composition range of 9–43% ClPIP by weight and pelletized under 10 t press. The pellets were irradiated in ⁶⁰Co Gammacell in air at room temperature to doses up to 300 kGy. The maximum electrical conductivity increase was observed for the blend PANI43 which changed from 10^?10 to 10^?4 S cm^?1 when it was irradiated to 300 kGy dose. Radiation induced changes on the blends were also studied by UV–vis spectroscopy using reflection technique and FTIR spectroscopy. The broad absorption band in the visible range (630 nm) increased by increasing irradiation dose. The band (1110 cm^?1) in the IR spectra which is indicative of conductivity showed linear correlation with irradiation dose.     

Synthesis,Crystal Structure and Spectroscopic Characterization of {6-[2-(2-chlorophenyl)-1,3-thiazol-4-yl]-2-oxo-1,3-benzothiazol-3(2<Emphasis Type="Italic">H</Emphasis>)-yl}acetic acid

Abstract  

The title compound {6-[2-(2-chlorophenyl)-1,3-thiazol-4-yl]-2-oxo-1,3-benzothiazol-3(2H)-yl}acetic acid was prepared and characterized by elemental analyses, FT-IR, ¹H NMR spectroscopy, X-ray diffraction. A quantum-chemical calculation was performed using the CNDO method. In the title compound, C₁₈H₁₁ClN₂O₃S₂, the crystal structure is stabilized by intermolecular hydrogen bonds (C–H···O=C) to form centrosymmetric R₂² R_{2}^{2} (16) dimers and the C–H···O, O–H···N, and C–H···N interactions generating the graph set motifs R₂² R_{2}^{2} (9) and R₂² R_{2}^{2} (22).     

Fluctuating in the hopping rate of CuO thin films with respect to substrate temperature

Electrical transport properties in CuO thin films processed using d.c. magnetron sputtering technique is investigated to understand the correlation between the processing conditions and electrical properties. It is identified that the temperature dependent conductivity of the investigated films is controlled by the multi-phonon hopping conduction mechanism. A detailed analysis in terms of carrier hopping parameters is used to correlate electrical transport properties with the d.c. magnetron sputtering conditions.     

Research activity and the state of astrosciences in Turkey

Conclusions The above analysis on the macro characteristics of research activity indicates that, in spite of the observed low level of national research output, research in astrosciences has shown quite a rapid progress in the last two decades. The productivity of astronomers — now about 0·3 publications/researcher per year — can be improved by making the scientific environment more conductive to research.     

Iron(III) chloride-catalyzed convenient one-pot synthesis of β-acetamido carbonyl compounds

A one-pot multi-component reaction of aldehydes, enolizable ketones or 1,3-dicarbonyls, acetonitrile/benzonitrile, and acetyl chloride is described for the preparation of β-acetamido carbonyl compounds using FeCl₃·6H₂O as a mild, inexpensive, and highly efficient catalyst. The effect of substrate as well as substituent for multi-component reaction versus Knoevenagel condensation is also illustrated. The key features of this methodology are operational simplicity, mild reaction conditions, and good yields.     

Reaction of zinc enolates derived from 1-aryl-2,2-dibromoalkan-1-ones with tetramethyl 2,2′-(1,4-phenylenedimethylidene)dimalonate,dimethyl 3,3′-(1,4-phenylene)bis(2-cyanoacrylate), and 2,2′-(1,4-phenylenedimethylidene)-bis(malononitrile)

Zinc enolates derived from 1-aryl-2,2-dibromoalkanones reacted with tetramethyl 2,2′-(1,4-phenylenedimethylidene)dimalonate, dimethyl 3,3′-(1,4-phenylene)bis(2-cyanoacrylate), and 2,2′-(1,4-phenylenedimethylidene)bis(malononitrile) to give, respectively, tetramethyl 3,3′-(1,4-phenylene)bis(2-alkyl-2-aroylcyclopropane-1,1-dicarboxylates), dimethyl 3,3′-(1,4-phenylene)bis(2-alkyl-2-aroyl-1-cyanocyclopropane-1-carboxylates), and 3,3′-(1,4-phenylene)bis(2-alkyl-2-aroylcyclopropane-1,1-dicarbonitriles) as a single stereoisomer.     

Isomerization of N,N,N′-trifluoroalkylamidines

Conclusions The syn-isomers of N,N,N-trifluorobutyramidine and N,N,N-trifluoromonochloroacetamidine are isomerized in the presence of HCl to the anti-form. The isomerization of the syn-isomer of N,N,N-trifluoromonochloroacetamidine also proceeds in the presence of ethanol.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2159–2160, September, 1973.