Analysis of thermodynamic parameters of glass forming metallic melts

The temperature dependence of the Gibbs free energy difference (G) between the undercooled liquid and the corresponding equilibrium solid has been analysed for metallic glass forming systems in the frame of the expression obtained by expanding free energies of the undercooled liquid and solid phases in the form of Taylor's series expansion. The enthalpy difference (H) and the entropy difference (H) between the undercooled liquid and solid phases have also been analysed. The study is made for five different metallic glass forming materials, Au₇₇Ge_13.6Si_9.4, Au_53.2Pb_27.5Sb_19.3, Au_81.4Si_18.6, Mg_85.5Cu_14.5 and Mg_81.6Ga_18.4 and a very good agreement is found between calculated and experimental values of G. The ideal glass transition temperature (T _k) and the residual entropy (S _R) of these materials have also been studied due to their important role in assigning the glass formation ability of materials.The authors are grateful to Prof. P. Ramachandrarao, N. M. L. Jamshedpur and Prof. S. Lele, Department of Metallurgical Engineering, B. H. U. for their interest in the present work. The part of work was done under C. S. I. R. project and we are also thankful to C. S. I. R., New Delhi for financial support.     

Stepwise substitution of oxo-centered,trinuclear chromium(III) carboxylates with Schiff base

Oxo-centered, trinuclear, mixed-ligand complexes of chromium(III) have been synthesized by stepwise substitutions of acetate ions of [Cr₃O(OOCMe)₄(OOCR)₃] · 3MeOH (1) and the isolated products of the type [Cr₃O(OOCMe)₂ (SB)(OOCR)₃]PF₆ · 3MeOH (2), [Cr₃O(OOCMe)(SB)₂(OOCR)₃]PF₆ · 3MeOH (3) and [Cr₃O(SB)₃(OOCR)₃]PF₆ · 3MeOH (4) [where R = C₁₃H₂₇ and HSB = C₆H₄(OH)CHNC₆H₄Cl] have been characterized by a full battery of complementary physico–chemical methods including spectral (infrared, electronic, FAB mass and powder XRD) studies, elemental and thermogravimetric analyses, molar conductance and magnetic susceptibility measurements. The infrared spectra suggest the bridging nature of both carboxylate and Schiff base anions along with ν _asym(Cr₃O) vibrations in the complexes. The trinuclear nature of the complexes has been assessed from FAB mass data. Electronic spectra and magnetic moment values were consistent with chromium(III) ion present in an octahedral environment which was supported by their powder X-ray diffraction data. Cyclic voltammetric data of complex (4) indicate a reversible oxidation wave and an irreversible reduction wave in the range − 1.2–0.6 V. The decomposition pathway of all the complexes has been discussed on the basis of thermogravimetric analysis data. Conductance data indicate the monocationic nature of the complexes and their plausible structure has been established on the basis of above physico–chemical studies.     

4‐(3,17‐Dioxoandrost‐4‐en‐16‐ylidenemethyl)benzonitrile

The title compound, C₂₇H₂₉NO₂, has the outer six‐membered ring in a sofa conformation, while the central rings are in chair conformations. The five‐membered ring adopts a slightly distorted 13β,14α‐half‐chair conformation. The cyano­benzyl­idene moiety has an E configuration with respect to the carbonyl group at position 17.     

On-matrix derivatisation-extraction of precursors of nitrogen- and sulfur-mustards for verification of chemical weapons convention

Development and refinement of sample preparation protocols for retrospective detection and identification of chemical warfare agents (CWAs) and their markers is of paramount importance from verification point of view of chemical weapons convention (CWC). Precursors of nitrogen- and sulfur-mustards (NMPs and SMPs) are polar adsorptive markers of vesicant class of CWAs. Their detection in a given environmental sample may imply past contamination with mustards. For the efficient extraction of NMPs and SMPs from soil, on-matrix derivatisation-extraction (OMDEX) method was developed and optimized. The method involved trifluoroacetylation of analytes on soil itself, followed by extraction with suitable solvent. The extracted samples were analyzed by gas chromatography-mass spectrometry (GC-MS). This virtually single-step sample preparation offered better recoveries of NMPs and SMPs in comparison to conventionally used extraction, evaporation and derivatisation. The best recoveries of analytes were obtained with acetonitrile by OMDEX method. Dynamic linearity range of trifluoroacetylated (TFA) derivatives of NMPs and SMPs was 1-12 microg/L in GC-MS analysis in SIM mode. Repeatability and reproducibility of this technique containing 5 and 10 microg analytes/gm soil was <3.3% and <4.6%, respectively. OMDEX technique was finally applied for the detection of TFA derivatives of NMPs in the soil sample supplied in 16th official proficiency test conducted by OPCW in October 2004.     

Analysis of lattice thermal conductivity and phonon-phonon scattering relaxation rate: Application to Ge

The three-phonon scattering relaxation rates and their temperature exponents have been analysed in the frame of Guthrie's classification of the phonon-phonon scattering events as class I and class II events and as a result of this, a new expressionτ _3ph ^-1 =(B _N,I+B _U,Ie^-θ/αT) g(w)T ^m I ^(T)+(B _N,II+B _U,IIe^-θ/αT)g(w)T ^mII^(T) for the three phonon scattering relaxation rates has been proposed for the first time to calculate the lattice thermal conductivity of a sample. Using the expression proposed above, the lattice thermal conductivity of Ge has been analysed in the temperature range 2–1000K and result obtained shows a very good agreement with the experimental data. The percentage contributions due to three-phonon normal and umklapp processes are also reported. The role of four phonon processes is also included at high temperatures. To estimate an approximate value of the scattering strength and the phonon conductivity, the analytical expression is also obtained in the frame of the expression proposed above forτ _3ph ^-1 .     

Semistable laws on topological vector spaces

Summary In this paper we discuss three types of results: Firstly, we present two Lévy-Hinin type representations of Poisson type infinitely divisible (i.d.) laws on certain topological vector (TV) spaces; one of these complements a known representation due to Dettweiler. Secondly, we define and characterize r-semistable laws on locally convex TV spaces and also obtain good representation of their characteristic functions. Finally, we discuss the existence and the continuity of the semigroup { _tt>0} of i.d. laws on locally convex TV spaces. These complement similar known results of Siebert.The research of this author is partially supported by the Office of Naval Research under contract No. N0014-78-C-0468     

4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophen‐4‐one (CPDTO) homopolymer with side chains on every other CPDTO

A soluble 4H‐cyclopenta[2,1‐b ;3,4‐b ′]dithiophene‐4‐one (CPDTO)‐based polymer (C₆‐PCPDTO) has been synthesized from two monomers derived from nonalkylated CPDTO and didodecyl CPDTO (C₁₂‐CPDTO). Proton NMR, thermal analysis, UV–vis absorption, cyclic voltammetry, and XRD are used to characterize the polymer in solution and film. The new polymer has an optical bandgap of 1.28 eV in film, and has strong interchain interaction in chloroform solutions. The polymer contains a significant amount of homocoupled segments. The regular segments and homocoupled CPDTO segments render the polymer highly aggregating in solution. The non‐planar homocoupled C₁₂‐CPDTO segments prevent the polymer from forming regular π‐stacks, resulting in a low SCLC hole mobility (3.88 × 10^?7 cm²V^?1s^?1). CV experiments show that C₆‐PCPDTO is stable in its oxidized and reduced states. Solar cell devices were fabricated from C₆‐PCPDTO2 :PC₆₀BM blends of different weight ratios. High PC₆₀BM loading (80% or greater) was required for the devices to show measurable efficiency, indicating that the limited π‐stacking of the polymer is not sufficient to cause effective phase separation. Further development of synthetic method is still needed to eliminate structural defects so that long‐range ordered pi‐stacking can be realized in the polymer for these applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1077–1085     

Facile Syntheses of Histamine- and Imidazole-4-propionic Acid–Derived Room-Temperature Ionic Liquids

We report synthesis of histamine- and imidazole-4-propionic acid–based ionic liquids containing a variety of alkyl and aryl groups placed at the two different positions of the constituent imidazole ring in convenient steps in good yields.