Mesoscopic Modeling of Capillarity-Induced Two-Phase Transport in a Microfluidic Porous Structure

Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant.     

Intramolecular C-H activation by inferred terminal cobalt imido intermediates

Reaction of TpR,MeCo(I) dinitrogen complexes (R = iPr, tBu) with trimethylsilyl azide yields structurally characterized compounds that imply the formation of reactive intermediates of the type TpR,MeCo=NSiMe3. These cobalt imido species apparently abstract hydrogen from the 3-substituent of the Tp-ligand, leading to the formation of amido complexes accompanied by either Co-C bond formation (R = tBu) or C-C bond formation (R = iPr).     

Tamarindus indica mucilage and its acrylamide-grafted copolymer as flocculants for removal of dyes

The application of Tamarindus indica seed mucilage (Tam), a food grade polysaccharide, and its acrylamide grafted copolymer as flocculants was assessed for the first time for removal of various types of dyes from model textile wastewater containing azo, basic, and reactive dyes. Acrylamide grafted T. indica mucilage (Tam-g-PAM) was obtained by ceric ion initiated polymerization technique. A series of contact time experiments were conducted to assess the system variables such as concentrations of mucilage and dyes and pH. These flocculants reduce the dye concentration by flocculation and settling. The grafted copolymer, Tam-g-PAM showed better results for dye removal. The optimal flocculant concentration, which was required to effect flocculation, was independent of dye concentration within the range examined. Both the flocculants performed better for removal of azo dyes than for reactive and basic dyes.     

Moderating the nucleophilicity of the sulfide ligands in the dinuclear {Pt2S2} metalloligand system using triphenylarsine

Reaction of cis-[PtCl₂(AsPh₃)₂] with excess sodium sulfide in benzene gave the triphenylarsine analogue of the well-known metalloligand [Pt₂(μ-S)₂(PPh₃)₄] as an orange solid.The compound was characterised by detailed mass spectrometry studies, and by conversion to various alkylated and metallated derivatives.The sulfide ligands in [Pt₂(μ-S)₂(AsPh₃)₄] are less basic than the triphenylphosphine analogue, and the complex gives a relatively weak [M+H]⁺ ion in the positive-ion electrospray (ESI) mass spectrum, compared with the phosphine analogue.Methylation of an equimolar mixture of [Pt₂(μ-S)₂(PPh₃)₄] and [Pt₂(μ-S)₂(AsPh₃)₄] with MeI gave the species [Pt₂(μ-S)(μ-SMe)(AsPh₃)₄]⁺ and [Pt₂(μ-SMe)₂(PPh₃)₃I]⁺, indicating a reduced tendency for the sulfide of [Pt₂(μ-S)(μ-SMe)(AsPh₃)₄]⁺ to undergo alkylation.The lability of the arsine ligands is confirmed by the reaction of an equimolar mixture of [Pt₂(μ-S)₂(PPh₃)₄] and [Pt₂(μ-S)₂(AsPh₃)₄] with n-butyl chloride, giving [Pt₂(μ-S)(μ-SBu)(EPh₃)₄]⁺ (E = P, As), which with Me₂SO₄ gave a mixture of [Pt₂(μ-SMe)(μ-SBu)(PPh₃)₄]²⁺ and [Pt₂(μ-SMe)(μ-SBu)(AsPh₃)₃Cl]⁺.Reactivity towards 1,2-dichloroethane follows a similar pattern.The formation and ESI MS detection of mixed phosphine-arsine {Pt₂S₂} species of the type[Pt₂(μ-S)₂(AsPh₃)_n(PPh₃)_4−n] is also discussed. Coordination chemistry of [Pt₂(μ-S)₂(AsPh₃)₄] towards a range of metal-chloride substrates, forming sulfide-bridged trinuclear aggregates, has also been probed using ESI MS, and found to be similar to the phosphine analogue. The X-ray crystal structure of [Pt₂(μ-S)₂(AsPh₃)₄Pt(cod)](PF₆)₂ (cod = 1,5-cyclo-octadiene) has been determined for comparison with the (previously reported) triphenylphosphine analogue. ESI MS is a powerful tool in exploring the chemistry of this system; in some cases the derivatising agent p-bromobenzyl bromide is used to convert sparingly soluble and/or poorly ionising {Pt₂S₂} species into soluble, charged derivatives for MS analysis.     

The satellite-shaped Co-15 Polyoxotungstate, [Co6(H2O)30{Co9Cl2(OH)3(H2O)9(beta-SiW8O31)3}]5-

The 15-cobalt-substituted polyoxotungstate [Co(6)(H(2)O)(30){Co(9)Cl(2)(OH)(3)(H(2)O)(9)(beta-SiW(8)O(31))(3)}](5-) (1) has been characterized by single-crystal XRD, elemental analysis, IR, electrochemistry, magnetic measurements, and EPR. Single-crystal X-ray analysis was carried out on Na(5)[Co(6)(H(2)O)(30){Co(9)Cl(2)(OH)(3)(H(2)O)(9)(beta-SiW(8)O(31))(3)}].37H(2)O, which crystallizes in the hexagonal system, space group P6(3)/m, with a = 19.8754(17) A, b = 19.8754(17) A, c = 22.344(4) A, alpha= 90 degrees, beta = 90 degrees, gamma = 120 degrees, and Z = 2. The trimeric polyanion 1 has a core of nine Co(II) ions encapsulated by three unprecedented (beta-SiW(8)O(31)) fragments and two Cl(-) ligands. This central assembly {Co(9)Cl(2)(OH)(3)(H(2)O)(9)(beta-SiW(8)O(31))(3)}(17-) is surrounded by six antenna-like Co(II)(H(2)O)(5) groups resulting in the satellite-like structure 1. Synthesis of 1 is accomplished in a simple one-pot procedure by interaction of Co(II) ions with [gamma-SiW(10)O(36)](8-) in aqueous, acidic NaCl medium (pH 5.4). Polyanion 1 was studied by cyclic voltammetry as a function of pH. The current intensity of its Co(II) centers was compared with that of free Co(II) in solution. Our results suggest that 1 keeps its integrity in solution. Magnetic susceptibility results show the presence of both antiferro- and ferromagnetic coupling within the (Co(II))(9) core. A fully anisotropic Ising model has been employed to describe the exchange-coupling and yields g = 2.42 +/- 0.01, J(1) = 17.0 +/- 1.5 cm(-1), and J(2) = -13 +/- 1 cm(-(1). Variable frequency EPR studies reveal an anisotropic Kramer's doublet.     

Studies in spiroheterocycles. Part XVII. synthesis of novel fluorine containing spiro[indole-pyranobenzopyran] and spiro[indenopyran-indole] derivatives

An elegant one-step synthesis of two novel spiro ring systems viz: spiro[3H-indole-3,4′-(2′-amino-3′-carbonitrile-[4′H]-pyrano[3,2-c]benzopyran)]-2,5′(1H)-dione8 and spiro[(2-amino-3-carbonitrile-indeno[1,2-b]pyran)-4(5H)>3′-[3H]indole]-2′,5(1′H)-diones in 80–85% yields is described. The spiro heterocycles were prepared by the reactions of fluorine containing 3-dicyanomethylene-2H-indol-2-ones with 4-hydroxy-2H-1-benzopyran-2-one and 1H-indene-1,3(2H)-dione respectively. The synthesized compounds have been characterized on the basis of elemental analyses, ir, pmr, ¹⁹F nmr and mass spectral data.     

Fly‐Ash‐Supported Synthesis of 2‐Mercaptobenzothiazole Derivatives under Microwave Irradiation

Microwave‐assisted, solvent‐free alkylation and acylation of 2‐mercaptobenzothiazole has been attempted using silica gel, alumina, and a new solid support, fly ash. Fly ash, a waste generated at thermal power stations, could be used as solid support just as efficiently as commercial supports. The additional features of methodology include a much faster reaction, easy workup, higher yields, higher purity of the products, and an ecofriendly approach.     

Identification of markers of thermal processing (“roasting”) in aqueous extracts of Coffea arabica L. seeds through NMR fingerprinting and chemometrics

Roasting of Coffea arabica L. seeds gives rise to chemical reactions that produce more than 800 compounds, some being responsible for the desired organoleptic properties for which the beverage called “coffee” is known. In the industry, the “roasting profile,” that is, the times and temperatures applied, is key to influence the composition of roasted coffee beans and the flavour of the beverage made from them. The impact of roasting on the chemical composition of coffee has been the subject of numerous studies, including by nuclear magnetic resonance (NMR) spectroscopy. However, the roasting equipment and profiles applied in these studies are often far from real industrial conditions. In this work, the effects of two critical technological parameters of the roasting process, namely, the “development time” (the period of time after the “first crack,” a characteristic noise due to seed disruption) and the final roasting temperature on coffee extracts, were investigated. Seeds were roasted at pilot scale according to 13 industrial roasting profiles and extracted in D₂O. The extracts were analysed by ¹H NMR experiments. The NMR spectra were compared using (a) quantitative analysis of main signals by successive orders of magnitude and (b) chemometric tools (principal component analysis, partial least squares and sparse-orthogonal partial least squares analysis). This allowed to identify compounds, which may serve as markers of roasting and showed that changes in chemical composition can be detected even for slight change in final temperature (~1°C) or in total roasting time (~25 s).     

Ln0.5A0.5MnO3 (Ln=Lanthanide,A= Ca,Sr) Perovskites Exhibiting Remarkable Performance in the Thermochemical Generation of CO and H2 from CO2 and H2O

Perovskite oxides of the Ln_0.5A_0.5MnO₃ (Ln=lanthanide, A=Sr, Ca) family have been investigated for the thermochemical splitting of H₂O and CO₂ to produce H₂ and CO respectively. The amounts of O₂ and CO produced strongly depend on the size of the rare earth ions and alkaline earth ions. The manganite with the smallest rare earth possessing the highest distortion and size disorder as well as the smallest tolerance factor, gives out the maximum amount of O₂, and, hence, the maximum amount of CO. Thus, the best results are found with Y_0.5Sr_0.5MnO₃, which possesses the highest distortion and size disorder. Y_0.5Sr_0.5MnO₃ shows remarkable fuel production activity even at the reduction and oxidation temperatures as low as 1200 °C and 900 °C, respectively.