C-13 and H-1 NMR Study of Alkyl and Aryl-Substituted 1-(4′-Dimethylaminobenzylideneamino)pyridinium Perchlorates

C-13 and H-1 NMR spectra of some 1-(4′-dimethylaminobenzylideneamino)pyridinium perchlorates show that the angle of twist of the pyridine ring in unsubstituted, 1, and 2-alkyl substituted compounds 2–5 is comparable. However, it is considerably increased in 2,6-dialkyl derivatives. As seen from the spectral data, pyridine and phenyl rings in 2,6-diphenyl derivative 15 are not coplanar. The effect of 4-alkyl substituent is of hyperconjugative chacter. In general, the amount of the positive charge at C-4 in 2,6-dialkyl substituted salts is higher as compared to 2-monosubstituted compounds.     

The influence of fast neutron irradiation on the IR optical properties of NTD-Silicon

Optical IR measurements of NTD-Si are presented for different fast neutron doses. The exponential dependence of the divacancy concentration and the near-edge absorption as a function of fast neutron flux is reported. Silicon one-phonon absorption, caused by the irradiation, is also increasing with the rising percentage of fast neutrons in the flux     

Algebraic index theorem

We prove the Atiyah-Singer index theorem where the algebra of pseudodifferential operators is replaced by an arbitrary deformation quantization of the algebra of functions on a symplectic manifold.Partially supported by NSF Grant DMS-9101817.     

The magnetic field,force and inductance of the system consisting of a thin ellipsoidal coil and a ferromagnetic ellipsoid

The method of separation of variables has been applied to determine the magnetic field of the system consisting of a thin ellipsoidal coil and a ferromagnetic ellipsoid of revolution. The inductance and the force acting between the coil and the ellipsoid are also examined.     

Separation of mixtures of sodium and potassium ions by charge mosaic dialysis

Charge mosaic membranes contain a mixture of anionic and cationic elements separated by thin neutral regions. In order to maintain eloctroneutrality, the overall flux of salts from electrolytic solutions through such membranes must occur with equal transport of cationic and anionic charge. The flux rate depends on the resistivities of the exchange elements and the solution composition. It is shown that Na⁺ and K⁺ can have vastly different relative transport rates depending on the selection of the membrane formulation and the receiver composition. The effect is attributed to ionic polarization of the membrane.     

Separation techniques in speciation analysis for organometallic species

A comprehensive review of the state-of-the-art of the separation of various organically-bound metals and metalloids for speciation analysis is presented. Recent developments in chromatographic (gas, liquid and supercritical fluid), electrophoretic (free-flow and gel) and fractionation techniques are discussed, followed by a survey of pertinent applications to speciation analysis for organometals and metalloids. The required sample characteristics for a given separation technique are specified and appropriate derivatization procedures are characterized. Methods applicable to the speciation of organic species of a particular element in various matrices are critically evaluated.List of abbreviations APS ammonium pentanesulfonate - CCC counter current chromatography - CZE capillary zone electrophoresis - DBT dibutyltin - DCyT dicyclohexyltin - DDTC diethyldithicarbamate - DEAE diethylaminoethyl gel (anion exchanger) - DEL diethyllead - DET diethyltin - DMA dimethylarsinic acid - DMGe dimethylgermanium - DMHg dimethylmercury - DML dimethyllead - DMSb dimethylstibinic acid - DMT dimethyltin - DPhT diphenyltin - DPrT dipropyltin - EDTA ethylenediaminetetraacetate - FFF field flow fractionation - GC gas chromatography - HEPES 4-(2-hydroxyethyl)-1-piperazine-ethanesulfonic acid - HPLC high performance liquid chromatography - ICP inductively coupled plasma - IEC ion exchange chromatography - IIC ion interaction chromatography - LC liquid chromatography - MBT monobutyltin - MCyT monocyclohexyltin - MEA monoethylarsinic acid - MEHg monoethylmercury - MEL monoethyllead - MET monoethyltin - MIP microwave induced plasma - MMA monomethylarsonic acid - MMGe monomethylgermanium - MMHg monomethylmercury - MML monomethyllead - MMSb monomethylstibonic acid - MMT monomethyltin - MPhHg monophenylmercury - MPhT monophenyltin - MPrT monopropyltin - MS mass spectrometry - NAA neutron activation analysis - NaBS sodium 1-butanesulfonate - NaDS sodium dodecylsulfonate - NaPS sodium pentanesulfonate - PAGE polyacrylamide gel electrophoresis - PAR 4-(2-pyridylazo)resorcinol - PIXE proton induced X-ray emission - QF quartz furnace - RPC reversed phase partition chromatography - SDS sodium dodecyl sulfate - SEC size exclusion chromatography - SFC supercritical fluid chromatography - TBAP tetrabutylammonium phosphate - TAL tetraalkyllead - TBT tributyltin - TCyT tricyclohexyltin - TeEL tetraethyllead - TEL triethyllead - TeML tetramethyllead - TET triethyltin - TGME thioglycolic methyl ester - THF tetrahydrofuran - TMA trimethylarsinic acid - TMAH tetramethylammonium hydroxide - TMGe trimethylgermanium - TML trimethyllead - TMT trimethyltin - TPhT triphenyltin - TPrT tripropyltin - Tris tris(hydroxymethyl)aminomethane