Diffusion Structural Analysis Study of Titania Films Deposited by Sol-Gel Technique on Silica Glass

The diffusion structural analysis (DSA) was used to characterize microstructure changes of hydrous titania gel films under in situ conditions of heating. TG and DTA were used in order to elucidate the processes controlling the formation of anatase film during heating of hydrous titania gel film. The annealing of porosity and near surface structure defects of the dehydrated titania films was indicated by DSA in the temperature range 255–700°C as the decrease of radon release rate. It was demonstrated that the annealing was enhanced on heating in oxygen in comparison with heating in argon. The DSA experimental results were compared with model curves describing the radon diffusion mobility and the annealing of radon diffusion paths.     

STM/AFM studies of the evolution of morphology of electroplated Ni/W alloys

The surface morphology evolution of Ni/W alloys was studied, as a function of the alloy composition. Using the modified plating baths developed in our laboratory recently, electroplated Ni/W alloys with different W content, in the range of 7–67 atom percent (a/o), can be obtained. This was found to lead to different structures, ranging from polycrystalline fcc-Ni type structure to amorphous, followed by orthorhombic with increasing W content in the alloy. Powder XRD was studied to determine the crystal structures. Ex situ STM, AFM and SEM were used to study in detail the surface morphologies of the different alloys, and their evolution with increasing W content.

The important findings are that a mixture of two crystalline forms can give rise to an amorphous structure. Hillocks that are usually a characteristic of epitaxial growth can also exist in the amorphous alloys. Oriented scratches caused by stress can also be formed.

Up to 20 a/o of W is deposited in the alloys in crystalline form, with the fcc-Ni type structure. Between 20 and about 40 a/o an amorphous structure is observed, and above that an orthorhombic crystal structure is seen, which is characteristic of the NiW binary alloy. Careful choice of the composition of the plating bath allowed us to deposit an alloy containing 67 a/o W, which corresponds to the composition NiW₂.     

On the evaluation of the nonisothermal kinetic parameters of (GeS2)0.3(Sb2S3)0.7 crystallization using the IKP method

The isoconversional method suggested by Friedman and the invariant kinetic parameters method (IKP) were used in order to examine the kinetics of the nonisothermal crystallization of (GeS₂)_0.3(Sb₂S₃)_0.7. The objective of the paper is to show the usefulness of the IKP method both for determining the activation parameters as well as the model of the investigated process. It was shown that the kinetic triplet [(E, A, f(α), where E is the activation energy, A is the preexponential factor, and f(α) is the differential function of conversion], which results through the application of the IKP method, depends on the set of kinetic models considered. For different sets of kinetic models, proportional values of f(α) are obtained. A criterion for the selection of this set, the use of which lead to the true kinetic triplet corresponding to the analyzed process (E = 163.2 kJ mol^?1; A = 2.47 × 10¹² min^?1 and the Avrami‐Erofeev model, A_m, for m = 2.5–2.6 was suggested. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 309–315, 2004     

Stereochemistry of new nitrogen containing heterocyclic aldehyde. VII. Potentiometric, conductometric and thermodynamic studies of novel quinoline azodyes and their metal complexes with some transition metals

A novel series of quinoline azodyes (5-(4'-derivatives phenyldiazo)-8-hydroxy-7-quinolinecarboxaldehyde)) (HL1-HL5) has been prepared and characterized by elemental analyses, 1H-NMR and IR spectra. The IR spectral data indicate that the compounds can exist in two resonance structures. Proton-ligand dissociation constants of quinoline azodyes and their subsituted derivatives, and metal-ligand stability constants of their complexes with bivalent (Mn2+, Co2+, Ni2+, Cu2+) metal ions have been determined potentiometrically in 0.1 m KCl and 40% (v/v) dimethylformamide (DMF)-water mixture. The influence of substituents on the dissociation and stability constants was examined on the basis of the electron repelling property of the substituent. The order of the stability constants of the formed complexes was found to be Mn2+ < Co2+ < Ni2+ < Cu2+. The effect of temperature was studied and the corresponding thermodynamic parameters (deltaG, deltaH, deltaS) were derived and discussed. The stoichiometries of these complexes were determined conductometrically and indicated the formation of 1:1 and 1:2 (metal:ligand) complexes was indicated.     

Spectral Studies on Some Pyrimidine Derivatives in Different Solvents

The electronic absorption spectra of 2-aminopyrimidine (compound I), 2-amino-4-methylpyrimidine (compound II), 2-amino-4,6-dimethylpyrimidine (compound III), 2-amino-4,6-dimethoxypyrimidine (compound IV), 4-amino-2,6-dimethylpyrimidine (compound V), and 4,5-diamopyrimidine (compound VI) have been measured in water and in a series of different organic solvents. The solvent effects on the spectra are discussed and the solvent induced spectral shifts are analyzed in terms of different solute–solvent interaction mechanisms, using the multiple linear regression technique.     

Separation of peptides and proteins by capillary electrophoresis using acidic buffers containing tetraalkylammonium cations and cyclodextrins

A method for improving separations of peptides and other positively charged species in capillary zone electrophoresis with untreated capillaries using acidic buffers containing tetraalkylammonium cations is described. Tetramethylammonium and tetrabutylammonium cations dynamically modify the capillary surface, leading to a reversal in the direction of the electroosmotic flow. As a result, the adsorption of positively charged peptides and proteins is minimized, and resolution and peak capacity are improved as the migration of cationic analytes is counterbalanced by the electroosmotic flow. The combining effect of reversing electroosmotic flow and cyclodextrin inclusion complexation on separations of closely related peptides and a protein mixture, as well as tryptic digest of hemoglobin is demonstrated.     

PHOTOCHEMISTRY OF ALL-TRANS- AND 13-CIS-14,15-DIDEUTERIORETINAL

Abstract— All- trans - and 13- cis -14,15-dideuterioretinal were synthesized and their solution photochemistry examined. Quantum yields of trans → cis or cis → trans photoisomerization and the number and ratio of primary photoproducts, determined by high pressure liquid chromatographic analysis, are essentially identical to that of their corresponding retinal isomer. The C-14, C-15 carbon-hydrogen modes play no particularly important role in the deactivation of electronically excited linear polyenes related to retinal.     

The effect of implementation of the ISO 9000 on customer complaints; a 5-year follow-up study in a regional laboratory.

Although the importance of quality management in the medical laboratory has been emphasized, we are unaware of any interventional studies demonstrating benefits of implementation of recommendations of the International Standards Organization (ISO). In the following 5-year follow-up study, we implemented quality management as stipulated by the ISO, received a certificate of approval, and determined how the program affected customer complaints. From 1997 to 2001 there was only a slight decrease in the number of customer complaints, but a significant continuing downward trend in the proportion of justified complaints (chi-squared test, p<0.001). In fact in 2001 the proportion of justified complaints had decreased by nearly 80% (relative risk, 0.22; 95% confidence interval, 0.09–0.52)), to only 10.9% of the total complaints. We conclude that the use of the ISO 9000 along with good laboratory practice resulted in a significant decrease in the proportion of justified complaints.     

Asymmetric conjugate additions of chiral phosphonamide anions to alpha,beta-unsaturated carbonyl compounds. A versatile method for vicinally substituted chirons

Reactions of anions derived from chiral nonracemic allyl, crotyl, and cinnamyl bicyclic C(2)-symmetrical phosphonamides with alpha, beta-unsaturated cyclic ketones, esters, lactones, and lactams take place at the gamma-position of the reagents. The products are diastereomerically pure or enriched beta-substituted carbonyl compounds. The method also provides easy access to vicinal substitution of as many as three stereogenic centers including in some cases quaternary carbon atoms, in a one-pot sequence.