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The ability of several high-[kappa] materials to recover from the Fowler-Nordbeim stress-induced degradation is analyzed. The study of various structural differences in the dielectrics and charge centroids show that high temperature annealing can help in a complete recovery of the stress-induced damage in Hf[O.sub.2] molecules.

A peculiar selectivity toward four-membered ring formation of functionalized aminophosphonates over that of six-membered ring formation during synthesis of azaheterocyclic phosphonates is unraveled both on theoretical and experimental bases. Ab initio calculations predict higher reaction barriers for the gamma-anion due to restricted rotation about the C-N bond and due to highly strained transition states during ring closure.

The discovery of four new polymorphs of oxalyl dihydrazide, obtained by crystallization from solution under different conditions, including the use of different crystallization solvents is reported. The range of different hydrogen-bonding arrangements displayed by the different polymorphs, together with the fact that the N-H bonds of the N[H.sub.2] groups adopt different orientations with respect to the molecular plane, lead to several possible geometric permutations for hydrogen-bonding arrangements in the solid state.

Abstract -- Interaction in the system of 3-(2-hydroxy-3-sulfo-5-nitrophenylazo)pentadion-2,4 ([H.sub.2]L) and cationic surface-active substances (CSASs: cetylpyridinium chloride (CPCl), cetylpyridinium bromide (CPBr), and cetyltrimethylammonium bromide (CTABr)) is studied in the presence and [...]

The synthesis and characterization of a series of novel biscapped and monocapped tris(dioxime) Mn(II) complexes is examined. The X-ray crystal structure of the first cationic tris(dioxime) Mn(II) complex [Mn(CDOH)[sub.3]BPh]OH (CDO[H.sub.2] = 1,2-cyclohexanedione dioxime) reveals a distorted trigonal prismatic coordination geometry, with the MN(II) being bonded by six imine-N donors, and the structure can be considered as being the clathrochelate with the hydroxide counterion as a 'cap'.

The complex formed between 1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid and [Nd.sup.3+] at pH 7.5 is found to be a dinuclear dimer in the solid state, in which the alcoholic OH groups are deprotonated, and the alkoxo oxygens are coordinated to both [Nd.sup.3+] in a bridging position. Results of NMR studies of the [La.sup.3+] complex, the number and multiplicity of signals, and values of coupling constants are in agreement with the dinuclear dimer structure of the complex in solution.

Uniform [Zn.sub.x][Cd.sub.1-x]Se nanocrystals are prepared at the artificially designed water-oil interface using [Na.sub.2]-Se[O.sub.3], Cd{N[O.sub.3]}[.sub.2] and Zn{[N[O.sub.2]}[.sub.2] as precursors. The coating of a Si[O.sub.2] shell could transform the hydrophobic particles into hydrophilic particles, which could make the synthesis of various nanocrystals more simple and flexible.

DFT(PW91/TZP) calculations, including full geometry optimizations are carried out on iron(III)-nitro porphyrins, a class of intriguing and reactive molecules, and certain porphyrin analogues. It is observed that all the Fe(III)-nitro porphyrins studied exhibit extremely high adiabatic electron affinities, most notably through oxygen-atom transfer from the nitro group, but also by forming dinitro and nitro-nitrosyl complexes.

The experimental and computational results for the two-step redox system [[[Cl.sub.5]Os(NO)].sup.n-] n = 1-3 are discussed in comparison to the related one-step redox systems [[[Cl.sub.5]Ru(NO)].sup.n-] and [[[Cl.sub.5]Ir(NO)].sup.n-] (n = 1,2). In all three states of [[[Cl.sub.5]Os(NO)].sup.n-], the N bonded form is preferred over the NO-side-on bonded alternative.

Abstract -- Optical and colorimetric characteristics of 1-nitroso-2-naphthol-3,6-disulfonic acid (nitroso-R-salt) are studied in aqueous solutions at pH 4-10. Equations of calibration plots are obtained as the colorimetric functions of the [...]

A study to show that the polycationic H-bonded chains of dabcoH[Br.sup.6] are transformed into a different structure of H-bonded cations and anions by modest pressure of about 0.4 Gpa was conducted. The low-pressure triggering of this transformation has suggested that it is a possible source of defects in the real structure at normal conditions, where they can be responsible for anomalous dielectric properties, including relaxor-like behavior of NH...N hydrogen-bonded compounds.

A thorough investigation is performed of the temperature dependence of the emission lifetimes of the complexes for more thoroughly understanding the temperature-dependent behavior. Macrocyclic complexes of the type trans-(Cr(N4)(CN2)(super +), demonstrate significant variation in their room-temperature excited-state behavior, namely, the lifetimes of the (super 2)E(sub g) (O(sub h) excited states are 336, 23 and 0.24 mus, respectively.

The Fe(lll)-coordination chemistry of neuromelanin building-block compounds 5,6-dihydroxyindole (DHI), 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and 5,6-dihydroxyindole-N-methyl-indole (Me-DHI) and the neurotransmitter dopamine are explored in aqueous solution by anaerobic pH-dependent spectrophotometric titrations. Oxidation studies reveal that iron accelaretes the air oxidation of DHI and DHICA>.

The N-H...O hydrogen bonds are analyzed for formamide dimer and its simple fluorine derivatives representing a wide spectrum of more or less covalent interactions. An analysis of the interaction energy components for the systems considered indicates that the covalent character of the hydrogen bond is manifested by a markedly increased contribution of the delocalization term relative to the electrostatic interaction energy.

Multidimensional Frank-Condon simulations of the resonance enhanced multiphoton ionization (REMPI) and mass-analyzed threshold ionization (MATI) spectra of phenol-nitrogen are obtained from CASSCF, MRCI, and SACCI optimized geometries. Results are unsatisfactory in the REMPI simulations as the transitions associated with intermolecular modes are widely underestimated and much less intense than those associated with intramolecular modes.

Potential energy surfaces (PES) for rotation about the N-C(sp(supper 3)) or N-C(aryl) bond and energies of stationary points on PES for rotation about the C(sp(supper 2))-N bond are reported for methylthiourea, ethylthiourea, isopropylthiourea, tert-butylthiourea, and phenylurea, using the MP2/aug-ccpVDZ method. Results show conformational preferences and rational barriers in thiourea groups are compared with those found for urea groups.

Detailed analysis of Raman and Raman optical activity (ROA) of L-alanine zwitterion (ALAZW) revealed that shapes of the spectral bands are to a large extent determined by the rotation of the NH(sub 3)(supper +), CO(sub 2)(supper -), and CH(sub 3) groups. Experimental Raman and ROA spectra of four model dipeptides of different rigidities indicate that the broadening of spectral lines could be used as a general site-specific indicator of molecular rigidity or flexibility.

The relative stabilities of nonisomers, twenty-two species of nitrogen cage molecules, and the geometries and varieties of energies are investigated. The findings suggest that pentagons play an important role in the stability of a cage molecule, whereas the three-membered rings play the second one, and the layers in nitrogen cage molecules contribute to the relative stabilities.

The ion complexes NO3(super -)(HNO3)(sub n), n = 1-3, is studied by using ab initio calculations at the B3YLP/aug-cc-pVTZ level of theory. The calculations have shown small differences of energy in the variation of the two nitrate groups from planarity to an almost perpendicular form for n = 1 and in all the cases, binding energies close to that of covalent compounds are estimated.

The kinetics and mechanisms of the reactions of piperidine, pyrrolidine, and oxazolidine nitroxides with HO(sub 2)(super .)/O(sub 2)(super .-), (super .)NO2 and CO(sub 3)(super .-) radicals are reported along with the importance of target-oriented nitroxides. The results have not indicated any correlation between the kinetics of the removal of these radicals by nitroxides and their protective activity against biological oxidative stress and emphasize the importance of target-oriented nitroxides.

The photophysical properties of norfloxacin (NFX) and its derivatives are studied to evaluate the role of the free carboxylic acid and the nonprotonated piperazinyl group in the behavior of the 1,4-dihydro-4-oxoquinoline ring. Steady state and time-resolved fluorescence measurements at different pHs provide clear favorable evidence for singlet excited-state deactivation of NFX and its N(4')methyl derivative pefloxacin (PFL) through intramolecular electron transfer from the N(4') atom to the ring.

N,N-bis(salicyclidene)hydrazine (LI), a bis-2-hydroxybenzene-type ligand H2L, its tert-butyl derivative (LII) and the corresponding Zn(super 2+) complexes are synthesized and the photoreactions of the compounds in solution are studied. The observed weak but strongly Stokes shifted fluorescence signal of the ligands LI or LII is due to excited-state intramolecular proton transfer from the phenolic hydroxy group to the nitrogen of the methine bond, which is also indicated by quenching by water.

Abstract -- The extraction of nitrophenols with polymethine dyes of the common formula [R.sub.1]-(CH=CH)[.sub.3]-[R.sub.2], indolium and benzothiazolium derivatives was studied. The effect of the acidity of the solution, the nature [...]

Hugoniot equation-of-state data of shock compressed beta-Si4Al2O2N6 are determined to a pressure of 120 GPa. A comparison of the Hugoniot data and recovered samples suggests that the high-pressure CaTi2O4-type phase is not quenchable and quenched as an amorphorus phase although a large hysteresis is detected in the release path.

The cell surface post-translationally modified forms of a G-protein-coupled receptor (GPCR), the human bradykinin B2 receptor, is studied by examining the role of N-glycosylation in the dimerization of the human bradykinin B2 receptor. The results show that receptor sialylation and N-glycosylation participate with disulfide bonding in the stabilization of the cell surface human B2 receptor dimers.

N-(2-Mercaptopropionyl)gycine (tiopronin)-coated silver nanoparticles (average diameter of metal core=5 nm) were prepared by a modified Brust method. It is found that increasing the particular layer contributes to florescence enhancement.

The supramolecular assembly and spectroscopic and luminescent properties of gold (I) compounds with diphosphines and N,N'-bis-4-methylpyridyl oxalamide are reported. The disphosphines complexes form the rectangular structures with four gold (I) ions at the corners.

An experimental and computational document states that helices can influence the pK(sub a) of residues located at the N-terminus, but the real nature of this perturbation remains unclear. The origin of the effect of 3(sub10-) and alpha-polyalanine helices on the pKa of an N-terminal cysteine residue is examined in gas phase as well as in aqueous solution by means of density functional theory.

The enatiomeric synthesis of 7-methoxy-D-tryptophan ethyl ester was completed by combination of the Larock heteroannulation process with a Schollkopf-based chiral auxiliary in good yield. This ester was hen employed in the first regiospecific, stereospecific total synthesis of (+)-12-methoxy-N(sub a)-methylvellosimine, (+)-12-methoxyaffinisine, (--)fuchsiaefoline, and 12-methoxy-N(sub b)-methylvoachalotine in excellent overall yield.

An investigation is conducted on electromigration in Cu single single Damascene line capped with amorphous a-SiC(sub x)N(sub y)H(sub z) and fabricated with various T-based lines. The result is consistent with the dominant diffusion path being along the Cu/a-SiC(sub x)N(sub y)H(sub z) interface in the samples.

Epitaxial growth on 4H-SiC (0001) substates with 4 degree and 8 degree off-cut angles is investigated. Both growth rate and nitrogen doping show a dependence on the Ci/Si ration and off-cut angle.

The adsorption of the N atom on the M(111) (M = Cu, Ag, Au) surfaces is investigated by means of quantum chemical calculations using both cluster and slab models. Optimized results indicate that the basis set of the N atom has a distinct effect on the adsorption energy but an indistinct one on the equilibrium distance.

The study is carried out to investigate the mechanism of the photolysis of 2, 3-diazabicyclo[2.2.2]oct-2-ene (DBO) under direct and triplet sensitized irradiation. The high fluorescence yield and the extraordinarily long lifetime of the singlet excited DBO are due to the presence of relatively high barriers, both for the intersystem crossing and for C-N cleavage.

Three different polymers containing the N,N',N''-chelate ligand tris[2-(1-vinylimidazolyl)]phosphine are prepared. All three polymeric Cu complexes are found to efficiently promote the hydrolysis of activated phosphoesters with the relative activity being dependent on the nature of the polymer and the substrate.

A series of adducts involving the interaction of trimeric perfluoro-o-phenylene mercury and 1,1,5,5-tetramethylpentamethylene nitroxide (TEMPO) or 2-(phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (NIT-Ph) nitronyl radicals and their crystal structures are investigated. The magnetic susceptibility measurements carried out on these adducts suggest that trimeric perfluoro-o-phenylene mercury does not mediate significant coupling between organic radicals coordinated on either side of the trinuclear core.

An investigation of the surface morphology of CrN layers grown on MgO(001) as a function of deposition temperature T(sub s) between 600 and 800 degree Celsius and layer thickness t=75-230 nm by ultrahigh vacuum (UHV) sputter deposition is presented. The root-mean-square surface roughness for 230-nm-thick layers decreases from 18.8 to 9.3 to 1.1 nm as T(sub s) is raised from 600 to 700 to 800 degree Celsius.

A short temporal electrical impulse is generated during the nitridation of mixtures of titanium and titanium nitride by a high temperature moving reaction front. The generation of an electric field during a rapid high-temperature nitridation is most probably due to the different diffusion velocities of charge carriers through the growing titanium nitride shell during the initial stage of the reaction.

GaN(sub y)As(sub 1-x-y)Bi(sub x) alloy are grown by molecular-beam epitaxy using solid Ga, Bi, and As sources and nitrogen radicals generated from nitrogen gas in rf plasma. The photoluminescence (PL) spectra reveal that the PL peak energy of GaN(sub y)As(sub 1-x-y)Bi(sub x) alloy decreased with increasing GaBi and GaN molar fractions.

The temperature effect on the final vibrational state distributions for N2B was examined further for N2H+ and N2D+ recombination. The measured rate coefficient for dissociative recombination (DR) of N2H(super +) and HCO(super +) ions exhibit behavior with little temperature dependence.

The molecular and electronic structures and electron transport characteristics of a Co complex are investigated using ab initio density functional theory (DFT). The calculation shows that the extended molecule D(sub 2d) symmetrical structure with two ligands perpendicular to each other and the Co atom locates at the center of a distorted octahedron formed by six donor N atoms.

High quality (Q), freestanding, narrow beam supported film acoustic-wave resonators (FBARs) fabricated with silicon micromachining is described. The Al/ZnO/Al type FBAR is preferred to the Al/ZnO/Al/Si(sub x)N(sub y) type for wide bandwidth filters as the former type has larger electromechanical coupling constant and high Q factor.

A computational study of the N((super 4)S)+CH2Cl reaction is conducted. The results concluded that the reaction starts from the interaction of the nitrogen and carbon atoms, leading to the formation of an initial intermediate (NHCH2Cl), which is relatively stable.

A brief description on a preliminary theoretical study on the SiCN(super +)/SiNC(super +) + H2O reactions is presented. The results provide useful mechanistic information for the analogous ion-molecule reactions of the monovalent silicon-bearing ions.

Abstract -- A catalytic kinetic method (CKM) is presented for the determination of mercury(II) based on its catalytic effect on the rate of substitution of N-methylpyrazinium ion (Mp[z.sup.+]) onto hexacyanoferrate(II). [...]

A mixture of the tungsten allylimido complexes Cl(sub 4)(RCN)W[NC(sub 3)H(sub 5)] was examined as a single-source precursor for growth of tungsten nitride (WN(sub x)) or carbonitride [WN(sub x)C(sub y)] thin films. The nitrogen content was found to support the significance of facile N-C bond cleavage in the film growth.

The Al(super 3+) cation can be stabilized in the gas phase using ligands, which have the ability to act as powerful sigma electron donors and electron acceptors. The results suggest that chain or ring compounds containing the -C triple bond N group might act as successful sequestering agents for Al(super 3+) from aqueous solutions.

A demonstration of the stepwise double addition to the nitrido ligand bound in trans-[Os(super IV)(tpy)(CL)2(N)]PF6(trans-[Os(super VI) triple bond N](super +) is presented. The reactions exhibit new derivatiztion of the nitrido ligand on Os(super VI) equivalent N with its implied synthetic utility.

The reactions of tetrakis(dimethylamido)titanium, with alkyltrichlorosilane self-assembled monolayers terminated by -OH, -NH(sub 2), and -CH(sub 3) groups are investigated with X-ray photoelectron spectroscopy. The results show that it is possible to attach a transition metal coordination complex from the vapor phase to a surface with an appropriately functionalized self-assembled monolayer.

A new series of azulene-substituted aromatic amines and diamines with amphoteric redox behavior, N,N-di(6-azulenyl)-p-toluidenes and N,N,N',N'-tetra(6-azulenyl)-p-phenylenediamines are designed and synthesized. Azulene-substituted aromatic amines exhibit facile electrochemical oxidation owing to the amine substituent and also show electrochemical reduction because of the generation of an anion radical stabilized by the resonance effect between the two 6-azulenyl groups.

The viability of hydroxylamines as nucleophiles in transition-metal-catalyzed allylic substitution was examined. It was found that the oxygen atom of hydroxylamines having an N-electron-withdrawing substituent acts as a reactive nucleophile.