Trapped electrons in substoichiometric MoO3 observed by X-ray electron spectroscopy

Substoichiometric amorphous thin films of MoO₃ in both the transparent and absorptive forms have been studied by X-ray electron spectroscopy. The transparent films can be colored blue (absorptive) electrically or by UV irradiation. The electron distribution curve of the blue film exhibits a small band near the Fermi edge which is absent in the transparent sample. This new band is attributed to electrons trapped in positively charged anion vacancies in the substoichiometric MoO₃ lattice. This model provides an interpretation of the electrical conductivity and color of the films.     

Studies on the solvent extraction of yttrium thenoyltrifluoroacetonate

Studies of extractions of yttrium from aqueous solution into chloroform, benzene, methyl isobutyl ketone, and mixtures of these solvents, containing thenoyltrifluoroacetone are described. The effects of reagent concentration, added n-butylamine, and added fluoride were investigated. Values of pH$\text{1}\text{2}$ and P_e were determined, and identifications of the involved species are suggested.     

Characterization of dynamic and steady-state protein phosphorylation using a fluorescent phosphoprotein gel stain and mass spectrometry

Protein phosphorylation plays a vital role in the regulation of most aspects of cellular activity, being key to propagating messages within signal transduction pathways and to modulating protein function. Pro-Q Diamond phosphoprotein gel stain is suitable for the fluorescence detection of phosphoserine-, phosphothreonine-, and phosphotyrosine-containing proteins directly in sodium dodecyl sulfate (SDS)-polyacrylamide gels. The technology is especially appropriate for profiling steady-state and dynamic phosphorylation on a proteome-wide scale, as demonstrated through detection of the native phosphorylation of cardiac mitochondrial phosphoproteins and changes in this profile arising from the activity of a protein kinase. For example, Pro-Q Diamond phosphoprotein gel stain was employed to demonstrate that among the 46 subunits of the mitochondrial respiratory chain complex, NADH:ubiquinone oxidoreductase (complex I), a 42 kDa subunit is phosphorylated in the steady-state. However, exposure of mitochondria to cAMP-dependent protein kinase increases phosphorylation of this 42 kDa subunit and results in de novo phosphorylation of an 18 kDa subunit as well. Since Pro-Q Diamond dye binds to phosphorylated residues noncovalently, the staining technology is fully compatible with modern microchemical analysis procedures, such as peptide mass profiling by matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry and post-source decay analysis of peptide phosphorylation.     

Pre-resonance Raman intensity studies of TCNQ and TCNQ−

Pre-resonance Raman spectra have been obtained for TCNQ and LiTCNQ in acetonitrile solution using an Ar⁺—Kr⁺ laser and a tunable rhodamine 6G dye laser. Using the theory of Albrecht and Hutley, we have calculated frequency factors for the intensity variations for several symmetric vibrational modes of each molecule. The observed spectra for TCNQ and LiTCNQ with violet, blue, and green excitation give evidence for B-type resonance enhancement due to vibronic mixing between at least two violet and ultraviolet transitions. The Raman spectra for LiTCNQ with yellow, orange, and red excitation show A-type enhancement due to a single electronic excitation in the near infrared.     

Synthesis of 2,3,4,5-tetranitropyrrole

Dealkylation of 1-tert-butyl-2,3,4-trinitropyrrole in boiling trifluroacetic acid gave 2,3,4-trinitropyrrole, the structure of which was confirmed by X-ray crystallography. Treatment of this trinitropyrrole with nitric acid/oleum briefly at 60° gave 2,3,4,5-tetranitropyrrole.     

Synthesis of 8,9-dialkoxy-substituted tetrahydrobenz[h] isoquinolines

6,7-Dimethoxy-2-naphthylethylamine, prepared by the diborane reduction of 6,7-dimethoxy-2-naphtlialeneacetamide, underwent a Pictet-Spengler cyclization to form 8,9-dimethoxy-1,2,3,4-tetrahydrobenz[h]isoquinoline. This compound is identical with that obtained by reduction of the corresponding dihydrobenzisoquinoline prepared from formamide cyclization. 6,7-Dialkoxy-2-naphthaleneacetic acids, the key intermediates for the preparation of these amides, were obtained from 6,7-dialkoxy-2-acetonaphthones by a modified Willgerodt reaction.     

A system for defining reference materials applicable to all food matrices

Recently the subcommittee on Food Definition of the AOAC INTERNATIONAL Task Force on Methods for Nutrition Labeling proposed a Food Matrix Organizational System [4] to systematically judge the applicability of collaboratively studied methods over a range of food matrices. This system describes a food matrix by its location in one of nine sectors in a triangle, with each point of the triangle defined as representing 100% and the opposite side representing 0% of the normalized contents of each of three major components of FAT, PROTEIN and CARBOHYDRATE. Foods falling within the same sector would be chemically similar and thus should behave in a similar analytical manner. This same scheme can be used to select one or two food matrices representing each sector, for development of a series of reference materials representing all foods. The list of 5250 foods contained in the USDA Nutrient Data Base for Standard Reference has been sorted and matched to this schematic to determine the scope of the selection process. In addition the list of foods in the USDA Data Base for Food Consumption Surveys has been examined. Results and progress of this selection process are reported.     

Rapid activation analysis of trace vanadium in tissue using 3.8-minute vanadium-52

Submicrogram amounts of vanadium in rat liver tissue have been analyzed by rapid activation analysis. A 5-min radiochemical separation coupled with γ-ray spectrometry permitted utilization of the 3.8-min vanadium-52 radioisotope. With this procedure the lower limit of detection at a thermal neutron flux of 10¹² n/cm²/sec was about 3·10^-9 g of vanadium.     

Detection of phosphoproteins on electroblot membranes using a small-molecule organic fluorophore

A new formulation of the small-molecule organic fluorophore, Pro-Q Diamond dye, has been developed that permits rapid and simple detection of phosphoproteins directly on polyvinylidene difluoride (PVDF) or nitrocellulose membranes (electroblots). Protein samples are first separated by electrophoresis and then electroblotted to membranes, stained and destained, in an analogous manner as typically performed with Amido Black or Ponceau S dye staining of total protein profiles. After staining, blots are imaged using any of a variety of laser-based gel scanners, xenon-arc lamp-based gel scanners or charge-coupled device (CCD) camera-based imaging devices equipped with UV trans- or epi-illumination. The uncomplicated and reliable staining protocol delivers results in as little as 1 h and the limit of detection for the stain is typically 2-4 ng of phosphoprotein with a linear dynamic range of approximately 15-fold. Compared with traditional radiolabeling and antibody-based approaches, the new method offers significant advantages, including avoidance of radioactivity, no need for expensive antibodies, no requirement for blocking unoccupied sites on the membrane with protein or detergent solutions, no sequence context-specific binding to phosphorylated amino acid residues and the ability to analyze the native, steady-state phosphorylation of proteins obtained directly from tissue specimens or body fluids. Pro-Q Diamond dye binds directly and exclusively to the phosphate moiety, allowing it to detect the broadest spectrum of phosphorylated proteins possible. The stain binds noncovalently to phosphoproteins and is thus fully compatible with matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) or Edman sequencing. The blot stain is also compatible with standard colorimetric, fluorogenic, and chemiluminescent detection techniques employed in immunoblotting.