Internal extraction structure

Kordosky, G. A. Virnig, M. J. Mattison, P. Beta-diketone copper extractants structure and stability. International Solvent Extraction Conference, Cape Town, South Africa, Mar. 17-21, 2002, 360-365. 

In another application electrospinning [189] of PS-fo-P4VP(PDP)i.o supra-molecules was used to produce internally structured fibers with diameters in the range of 200-400 nm. Due to the block copolymer sample selected, self-assembly resulted in spherical P4VP(PDP) domains with the well-known internal lamellar structure. After the PDP was extracted from the fibers using methanol, porous fibers were obtained [190]. With this method, the thickness of the fibers can be tuned by adjusting the spinning conditions, and the size and nature of the pores can be controlled by the choice of block copolymer and amount of amphiphile. 

Ris. H., and Malecki. M. (199,3). High resolution field emission scanning electron microscope imaging of internal cell structures after Epon extraction from sections A new approach to correlative ultrastructural and immunocytochemical studies. 7. Stnia. Bio Ill, 148-157. 

By the 1980s most of the aluminosilicate zeolites currently used industrially were known, and the emphasis shifted to the study of these materials using a range of powerful new techniques that came of age at this time. These included, in particular, solid state NMR, X-ray and neutron powder diffraction analysis, high resolution electron microscopy and computational methods. All were ideal for the study of structural details of solids that were rarely available, and never used in industrial applications, other than as microcrystalline powders. All these techniques are applicable to the bulk of the solid - this in turn makes up the (internal) surface, which is accessible to adsorbed molecules. Since the techniques are able to operate under any conditions of gas pressure, they may be used to extract structural details in situ under the operating conditions of ion exchange, adsorption and catalysis. In particular, zeolitic systems have proved ideal for the study, understanding and subsequent improvement of solid acid catalysts. 

Nuclear Data Sheets, Academic Press, San Diego, Calif., TvaluatedNuclear Structure Data File (ENSDF), a computer database of nuclear stmcture data evaluated by an international network of evaluators, is maintained at the National Nuclear Data Center, Brookhaven National Laboratory. NUDNTis a computer database of decay data extracted from the ENSDF. 

To create our terminology containing both internal terms and external terms we semiautomatically extract terms from available external resources (e.g., MeSH, EMTREE, UniProt). Then we fit the extracted terms to our data structure and preserve the reference to the source system because sometimes terms are very specific to certain databases. We refer to the terms specific to a database as local terms. These local terms are stored in a dedicated data structure, the Metastore. It must be noted that we refer to accession codes and identifiers used in databases such as UniProt, RefSeq, and GO as local terms (see Tables 31.1 and 31.2). 

If all nuclei are assigned and the spectral parameters for the conformational analysis are extracted, a conformation is calculated - usually by distance geometry (DG) or restrained molecular dynamics calculations (rMD). A test for the quality of the conformation, obtained using the experimental restraints, is its stability in a free MD run, i.e. an MD without experimental restraints. In this case, explicit solvents have to be used in the MD calculation. An indication of more than one conformation in fast equilibrium can be found if only parts of the final structure are in agreement with experimental data [3]. Relaxation data and heteronuclear NOEs can also be used to elucidate internal dynamics, but this is beyond the scope of this article. 

The urine samples were analyzed using a modified version of a published method.8 The method involved fortification of the urine samples with an internal standard 3,4,5-trichloro-2-pyridinyl, which is a structural isomer of the 3,5,6-TCP metabolite of chlorpyrifos hydrolysis of labile acid conjugates to 3,5,6-TCP solvent extraction derivitization to the f-butyl-dimethylsilyl ester of 3,5,6-TCP and subsequent negative-ion chemical ionization gas chromatography/mass spectrometry (GC/MS) analysis. Creatinine was determined in urine using a modification of a method of Fabiny and Erting-shausen.9... 

It is critical when performing quantitative GC/MS procedures that appropriate internal standards are employed to account for variations in extraction efficiency, derivatization, injection volume, and matrix effects. For isotope dilution (ID) GC/MS analyses, it is crucial to select an appropriate internal standard. Ideally, the internal standard should have the same physical and chemical properties as the analyte of interest, but will be separated by mass. The best internal standards are nonradioactive stable isotopic analogs of the compounds of interest, differing by at least 3, and preferably by 4 or 5, atomic mass units. The only property that distinguishes the analyte from the internal standard in ID is a very small difference in mass, which is readily discerned by the mass spectrometer. Isotopic dilution procedures are among the most accurate and precise quantitative methods available to analytical chemists. It cannot be emphasized too strongly that internal standards of the same basic structure compensate for matrix effects in MS. Therefore, in the ID method, there is an absolute reference (i.e., the response factors of the analyte and the internal standard are considered to be identical Pickup and McPherson, 1976). 

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