Some observations on the accumulation potential in adsorptive stripping voltammetry

A newly named parameter, “initial scan potential”, the potential from which the voltammetric scan starts rather than the widely accepted accumulation potential, has been found to be responsible for some of the important features of voltammograms obtained in the adsorptive stripping voltammetry (AdSV) of some organochlorine compounds (DDT, Dieldrin, 2,4- dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid). The experimental evidence reported strongly confirms the nonfaradaic nature of the preconcentration step in adsorptive stripping voltammetry.     

The determination of periodate by infrared spectroscopy

An infrared method has been developed to determine periodate on the microgram scale. Periodate is precipitated in slightly acid solution with tetraphenylarsonium chloride and in presence of perchlorate as carrier. The precipitate is mixed with powdered potassium bromide and pressed into a disc. The base-line absorbance of the periodate band at 11.68 μ is calculated in order to find the concentration of periodate from a calibration curve. No interference is caused by perchlorate, permanganate, perrhenate, chlorate, iodate or bromate.     

The determination of nitrate by infrared spectroscopy

Summary Nitrate may be determined by precipitation with nitron acetate and determination of the absorbance at 7.3 in a potassium bromide disc. The results are reproducible at milligram levels with a standard deviation of around ±5%. The presence of twice the amount of nitrite, perchlorate, bromate, chlorate, chromate, periodate or iodide has no significant effect on the determination.

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Zusammenfassung Nach Fällung mit Nitronacetat läßt sich Nitrat durch Messung der Absorption bei 7,3 in Kaliumbromid bestimmen. Die Resultate sind im Milligramm-Maßstab mit einer Standardabweichung von etwa ±5% reproduzierbar. Die gleichzeitige Anwesenheit der doppelten Menge Nitrit, Perchlorat, Bromat, Chlorat, Chromat, Perjodat oder Jodid hat keinen merklichen Einfluß auf die Bestimmung.

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Résumé On peut doser les nitrates par précipitation par l'acétate de nitron et mesure de l'absorption à 7,3 sur pastille en bromure de potassium. Les résultats sont reproductibles à l'échelle du milligramme avec une déviation standard de ±5% environ. La présence d'une quantité double de nitrites, perchlorates, bromates, chlorates, chromates, periodates ou iodures ne produit pas d'effet important sur le dosage.

     

A thermal decomposition study of some nickel(II)thioureachloride complexes

TG/DTA and Thermal Degradation Mass spectrometry (TDMS) data are presented for a series of nickel(II)thiourea chloride complexes: NiL₄Cl₂:L=thiourea or methyl-, dimethyl-, tetramethyl-, di-n-butyl, naphthyl-, ethylene- or allylthiourea. Two different thermal decomposition mechanisms are proposed for these complexes, and it is apparent that the thermal decomposition mechanism adopted by a particular complex depends on the structure of the relevant thiourea ligand and not on the nature of the halide ligand or on the existence of geometrical isomerism for these complexes.

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Zusammenfassung Durch TG, DTA und thermodegradative Massenspektrometrie (TDMS) von Nickel(II)-thioharnstoff-chlorid-Komplexen, NiL₄Cl₂ (L=Thioharnstoff oder Methyl-, Dimethyl-, Tetramethyl-, Di-n-butyl-, Naphthyl-, Vinyl- oder Allylharnstoff), erhaltene Daten werden angegeben. Zwei verschiedene Mechanismen werden für die thermische Zersetzung vorgeschlagen. Es ist offensichtlich, daß der Mechanismus, nach der die thermische Zersetzung eines gegebenen Komplexes verläuft, von der Struktur des relevanten Thioharnstoffliganden und nicht von der Natur des Halidliganden oder vom Vorliegen einer geometrischen Isomerie abhängt.

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/ - NiL₄Cl₂, L= , -, -, -, ---, -, - . . , .

     

Multifunctional Reagents for Quantitative Proteome‐Wide Analysis of Protein Modification in Human Cells and Dynamic Profiling of Protein Lipidation During Vertebrate Development

Novel multifunctional reagents were applied in combination with a lipid probe for affinity enrichment of myristoylated proteins and direct detection of lipid‐modified tryptic peptides by mass spectrometry. This method enables high‐confidence identification of the myristoylated proteome on an unprecedented scale in cell culture, and allowed the first quantitative analysis of dynamic changes in protein lipidation during vertebrate embryonic development.     

Determination of human immunodeficiency virus-1 protease inhibitors in patient serum using free solution capillary zone electrophoresis.

The goal of this study was to develop a fast, inexpensive and quantitative method for serum determination of the human immunodeficiency virus protease inhibitors Crixivan (C), Viracept (V), Invirase (I) or Fortovase (F), and Norvir (N), using common conditions for isolation and analysis. The best separation procedure developed thus far involves uncoated silica capillary and a buffer containing formic acid and acetonitrile. This procedure allows us to analyze three drugs (C, V and I or F) in 15 min. Norvir requires different analytical conditions. These four drugs are isolated from patient sera with a mixture of ethyl acetate and hexane. Sensitivity of the capillary zone electrophoresis protocols is sufficient for the detection of these pharmacological agents at the lowest clinically relevant concentrations (0.1 microgram/ml).     

Towards quantification of the role of materials innovation in overall technological development

This article presents a method for quantitatively assessing the role of materials innovation in overall technological development. The method involves classifying the technical changes underlying the overall innovation process first within a set of functional categories and then within each category as a hierarchical array of technical changes. It is specifically found that about 2/3 of the total progress in computation over the past 40 years has been due to materials/process innovations. More speculatively, materials/process innovation contributes at least 20% of the progress in all areas and the relative contribution of materials/process innovation to overall technological progress has grown in the past few decades. © 2012 Wiley Periodicals, Inc. Complexity, 2012