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We provide a highly sensitive and selective assay to detect [Hg.sup.2+] in aqueous solutions using gold nanoparticles modified with quaternary ammonium group-terminated thiols at room temperature. The mechanism is the abstraction of thiols by [Hg.sup.2+] that led to the aggregation of nanoparticles. With the assistance of solar light irradiation, the detection limit can be as low as 30 nM, which satisfies the guideline concentration of [Hg.sup.2+] in drinking water set by the WHO. In addition, the dynamic range of detection is wide (3 x [10.sup.-8]-1 x [10.sup.-2] M). This range, to our best knowledge, is the widest one that has been reported so far in gold nanoparticle (AuNP)-based assays for [Hg.sup.2+]. 10.1021/ac1021503

The self-consistent-charges density-functional tight-binding (SCC-DFTB) method is used to investigate the behavior of ammonium cyanate in the solid state under high pressure. The results have shown that the transformation of ammonium cyanate into urea is strongly exothermic.

A new method was used to prepare thermally stable zirconia-based mesoporus materials by using zirconium sulfate as the zirconium source and cetyltrimethylammonium (CTMA) ion as the pore-directing agent with the aid of NaCl salt. It was found that a portion of the surfactant and sulfate ions were removed during the post-treatment which prevented the remaining sulfate groups from being reduced by the hydrogen-rich surfactant during the calcination process.

The ionization degrees of tetramethyl, tetraethyl, tetrapropyl and tetrabutylammonium dodecylsulfate micelles are investigated by applying the hypothesis that the aggregation number at a given temperature is determined solely by C(sub aq).

The first example of conversion of dinitrogen to ammonia mediated by a molecular sieve is discussed. The high porosity and facile electron transport properties of ammonia make it an ideal candidate for a catalytic support material for nitrogen reduction and incorporation reactions.

The optical and electronic properties of the J-aggregate of the dye THIATS (triethylammonium salt of 3,3'-bis[3-sulfopropyl]-5,5'-dichloro-9-ethylthiacarbocyanine) by application of the excitons theory is explained. This application is observed at the temperature range 5 to 130K and at room temperature.

Conductivity, density and adiabatic compressibility of dodecyldimethylbenzylammonium chloride in aqueous solution, under different range of temperatures are studied using the results of conductometric and densitometric measurements. The results displayed a shallow minimum of the critical micelle concentration (cmc) values at twenty-five degree centigrade, whereas the ionization degree of micelles increased and the standard free energy of micellization decreased with the increase in temperature.

The impact of remote intramolecular hydrogen bonds (HBs) in phenols and benzylammonium cations on the dissociation enthalpies of their O-H and C-N bonds is studied. The thermochemistries of the HBs and hydrogen bond acceptors (HBAs) are reflected in the transition states for hydrogen atom abstraction from phenols by free radicals and the fragmentation of ring-substituted ions to form the benzyl cations has shown similar intramolecular HB effects.

The secondary ammonium/crown ether binding motifs have helped in studying a series of self-sorting systems ranging from simple four-component mixtures through sequence-specific pseudorotaxanes to multiply threaded complexes. The error-correction steps during the self-assembly of multiply threaded pseudorotaxanes are monitored by electrospray mass spectrometry, when a mixed-flow microreactor is coupled to the ion source to cover second time scales.

The electrical performance at high temperature and low relative humidity of proton-conducting Nafion-based membranes is improved by preparing new materials based on Nafion 117 (N117) neutralized with triethylammonium ([TEA].sup.+]) and doped with the ionic liquid (IL) trifluoromethanesulfonate of triethylammonium (TEA-TF). The studies have shown that the lower water uptake, the improved thermal and mechanical stability and the good conductivity has made [[N117.sup.x-][([TEA.sup.+]).sub.x]/[(TEA-TF).sub.y]] a promising membrane to improve for application in proton exchange membrane fuel cells operating under anhydrous conditions at high temperatures.

Several measurements are conducted to explain the different mechanisms that are observed in the external and the internal guest binding of the highly charged supramolecular host in water. Enthalpy and entropy are shown to be the main causes of the external and internal binding respectively.

The application of a chiral supramolecular assembly for the enantioselective catalysis of the aza-Cope rearrangement of allyl enammonium cations is discussed. The discussed enantioselectivity is shown to highly increase with a decrease in the temperatures.

The synthesis and characterization of single-walled carbon nanotubes (SWNTs) filled with a zinc-containing quaternary ammonium based ionic liquid (ChZnCl3) inside is reported. The versatility of ionic liquids and the unique phase transition observed inside the SWNTs provide a new opportunity for modulation of the electronic properties of carbon nanotubes.

The exposure of alkylamine (AA) surfactants to C[O.sub.2] has resulted in the formation of alkylammonium-alkylcarbamate (AAAC) molecular pairs. Temperature-resolved powder x-ray diffraction of AAACs has shown anisotropic thermal expansion occurring along the a-direction of the unit cell.

Sum frequency generation vibrational spectroscopy is used for studying the gas-liquid interface of room-temperature ammonium and pyrrolidinium ionic liquids. The chain length dependence studies have shown that the contribution of the N[C[H.sub.3] vibration is masked by the chain for lengths of four carbons and more.

The synthesis and the phase equilibria measurements of quaternary ammonium salt ethyl(2-hydroxyethyl)dimethylammonium bis(trifluoromethylsulfonyl)imide ([C.sub.2]N[Tf.sub.2]) with water or aromatic hydrocarbons are described. The ionic liquid is found to be polar in nature and is capable of undergoing many interactions.

Differential scanning calorimetry and infrared spectroscopy of thin films are used for studying the thermodynamic properties of the ammonium nitrate/ammonium sulfate/water system at low temperatures. Phase diagram theory and Alkemade lines are used for predicting the solids that are stable at equilibrium for all concentrations and the decomposition of a solid is observed at low temperatures.

The thermotropic liquid-crystalline (LC) bicontinuous cubic ([Cub.sub.bi]) phases of ammonium salts have functioned as ion conductors by forming nano-ion channels. The studies have shown that the alignment free [Cub.sub.bi] phases have higher ionic conductivities than the non-aligned columnar phases.

The structure of N,N-dimethylethylenediammonium pentachloroantimonate(III), [[(C[H.sub.3]).sub.2]NH[(C[H.sub.2]).sub.2]N[H.sub.3]][Sb[Cl.sub.5]], NNDP, was investigated in the diamond-anvil cell. A crystallographic study of the behavior of NNDP is undertaken both to low temperature and high pressures to determine whether the structural evolution is due solely to the removal of thermal energy as temperature is decreased or whether the reduction of interatomic distances plays a dominant role.

The influence of deuteration on the crystal structure of the ammoniumzinc(II) Tutton salt and its deuterated analogue is studied. Results suggest, when the structures are compared at 298 and 110 K, then the Zn(H2O)6(super 2+) ions experience a slightly stronger compression along the Zn-O(9) direction and that the strains along Zn-O(7) and Zn-O(8) are nearly equal at 298 K than at low temperatures.

Reaction rates for the conservation of ice nanocrystals 3-D arrays, to the hemi- and monohydrates of ammonia, are determined for temperatures in the range 100 to 128 K. A diffusion coefficient for ammonia in the amorphous 'hemihydrate' is determined as 2.8 * 10(super -19) cm(super 2/s) at 102 K with E(sub a) = 15 Kcal/mol.