Water-soluble nanodiamond

Reduction of the graphenic edges of annealed nanodiamond by sodium in liquid ammonia leads to a nanodiamond salt that reacts with either alkyl or aryl halides by electron transfer to yield radical anions that dissociate spontaneously into free radicals and halide. The free radicals were observed to add readily to the aromatic rings of the annealed nanodiamond. Nanodiamonds functionalized by phenyl radicals were sulfonated in oleum, and the resulting sulfonic acid was converted to the sodium salt by treatment with sodium hydroxide. The solubility of the salt in water was determined to be 248 mg/L. Nanodiamond functionalized by carboxylic acid groups could be prepared by reacting 5-bromovaleric acid with the annealed nanodiamond salt. The solubility of the sodium carboxylate in water was found to be 160 mg/L.     

Hetero-oligophenylene-based AIEE material as a multiple probe for biomolecules and metal ions to construct logic circuits: application in bioelectronics and chemionics

New hetero-oligophenylene derivative (2) was synthesized which exhibits aggregation-induced emission enhancement (AIEE) in H(2)O/THF (80:20). The aggregates serve as a biological probe for three different proteins, that is bovine serum albumin (BSA), cytochrome?c, and lysozyme, and DNA in contrasting modes. Further, among 29 metal ions tested, the contrasting fluorescence behavior of aggregates of 2 is observed with only Pb(2+) and Pd(2+) ions. Multiple output logic circuits based upon the fluorescence behavior between BSA and cytochrome?c and between Pb(2+) and Pd(2+) ions are constructed.     

High internal phase CO2-in-water emulsions stabilized with a branched nonionic hydrocarbon surfactant

A nonionic-methylated branched hydrocarbon surfactant, octa(ethylene glycol) 2,6,8-trimethyl-4-nonyl ether (5b-C12E8) emulsifies up to 90% CO2 in water with polyhedral cells smaller than 10 microm, as characterized by optical microscopy. The stability of these concentrated CO2/water (C/W) emulsions increases with pressure and in some cases exceeds 24 h. An increase in pressure weakens the attractive van der Waals interactions between the CO2 cells across water and raises the disjoining pressure. It also enhances the solution of the surfactant tail and drives the surfactant from water towards the water-CO2 interface, as characterized by the change in emulsion phase behavior and the decrease in interfacial tension (gamma) to 2.1 mN/m. As the surfactant adsorption increases, the greater tendency for ion adsorption is likely to increase the electrostatic repulsion in the thin lamellae and raise the disjoining pressure. As pressure increases, the increase in disjoining pressure and decrease in the capillary pressure (due to the decrease in gamma) each favor greater stability of the lamellae against rupture. The electrical conductivity is predicted successfully as a function of Bruggeman's model for concentrated emulsions. Significant differences in the stability are observed for concentrated C/W emulsions at elevated pressure versus air/W or C/W foams at atmospheric pressure.     

Eulerian–Lagrangian simulations of unsteady gas–liquid flows in bubble columns

We studied the dynamics of gas–liquid flows in a rectangular bubble column using Eulerian–Lagrangian simulations. Three-dimensional, unsteady simulations were performed to simulate the dynamic characteristics of the oscillating bubble plume. The effect of superficial gas velocity and aerated liquid height-to-column width (H/W) ratio on the dynamic and time-averaged flow properties was studied and the simulated results were validated using wall pressure and voidage fluctuation measurements. The effect of lift force and numerical diffusion on the dynamic and time-averaged properties is discussed in detail. Further, the results obtained using the Eulerian–Lagrangian simulations were compared with the Eulerian–Eulerian simulations. The bubble scale information, which is otherwise lost in the Eulerian–Eulerian simulations, was validated using the voidage fluctuation measurements. Such experimentally validated Eulerian–Lagrangian models will be useful for the simulation of mass transfer and reactions in bubble columns.     

A single molecule switch based on two Pd nanocrystals linked by a conjugated dithiol

Tunneling spectroscopy measurements have been carried out on a single molecule device formed by two Pd nanocrystals (dia. ∼5 nm) electronically coupled by a conducting molecule, dimercaptodiphenylacetylene. TheI-V data, obtained by positioning the tip over a nanocrystal electrode, exhibit negative differential resistance (NDR) on a background M-I-M characteristics. The NDR feature occurs at ∼0.67 V at 300 K and shifts to a higher bias of 1.93 V at 90 K. When the tip is held in the middle region of the device, a Coulomb blockade region is observed (±∼0.3 V)     

Distinction between normal and leukemic bone marrow by water protons nuclear magnetic resonance relaxation times

Pulsed nuclear magnetic resonance studies have been carried out on bone marrow of normal human subjects and patients with leukemia: chronic myeloid leukemia (CML) and acute myeloid leukemia (AML). It was observed that the proton spin-lattice relaxation time (T₁) value was discriminatory in the normal and leukemic cases with a statistical significance of (p < 0.01). Ouabain treatment of cells did not show any perceptible change of T₁ value when compared with the nontreated cells, indicating that the concomitant cation effluxes do not affect spin-lattice relaxation time. The water contents of normal, leukemic, and ouabain treated cells were in the range 60%–80%. Higher Fe levels were encountered in the normal than the leukemic samples, while levels of Zn, Cu, Mn, Co, and Ni were elevated in the leukemic samples compared with the normals. Despite the T₁ differences observed, the multiparameter studies do not uniquely pinpoint factors responsible for the elevation of T₁ in the malignant state.     

Übergangsmetallchalkogenverbindungen. Spectrophotometric evidence for the existence of MoO3Se2− and WO3Se2− in aqueous solution. Electronic Spectra of the Ions MeOxSe4−x2− (Me = Mo,W)

A spectrophotometric investigation of the reaction between MeO₄^2? (Me?Mo, W) and gaseous H₂Se leading to the identification of the unknown monoselenoanions of molybdenum(VI) and tungsten(VI) is reported. The electronic spectra agree well with the theoretically predicted ones. Further a comparative study of the spectra of different seleno- and thio-anions was made. The first band in the electronic spectra of MoO₃Se^2? and WO₃Se^2? is due to the Se → metal charge transfer transition.     

Übergangsmetallchalkogenverbindungen. Evidence for the existence of new Thioanions of Vanadium and Rhenium by their electronic spectra

The reaction of MO (M = V, Re) with H₂S investigated by spectrophotometry, indicated the existence of two new thioanions VO₂S and ReOS. Their spectra are compared with known relationships in those of the thioanions of molybdenum and tungsten. A proposal for the electronic spectrum of VO₃S^3? is given.     

Resonance raman spectra and quantum yields of MoS42−

Resonance Raman scattering of MoS₄^2? was studied in aqueous solution by irradiating its strong 4700 Å absorption band with five different lines of an Ar⁺ laser. The vibrational structure of the resonance spectra is discussed. Cross sections and quantum yields for the total scattered radiation were determined using NO₃^? as an internal standard.