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1.
An automatic measurement and data handling system for activation analysis is described. The system comprises five automatic -spectrometers with sample changers, a central computer with four workstations and two communication networks, one to connect the gamma-spectrometers with the central computer and another to provide communication from the workstations to the central computer. The software comprises programs for control of the -spectrometers, communication between the different units, data handling and storage, interpretation of -spectra, calculation of element concentrations and creating reports. 相似文献
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A new oscillating capillary viscometer has been developed and used for measuring viscoelastic flow properties of dilute polymer solutions. These flow properties are determined from measurements of the pressure to volume flow relationships for sinusoidal flow in cylindrical glass capillaries. The theory for this measurement procedure is based upon the known theory for oscillatory flow of a viscoelastic fluid in circular tubes and which is presented with a few supplementations in this paper.The oscillatory flow is generated by a piezoelectric driver which is dipped directly into the aqueous solution. The advantage of this driver is that the excitation voltage for the piston is a direct measure of the motion of the piston. Changes in pressure are measured with a sensitive low-pressure quartz tranducer.The viscometer was tested with aqueous glycerol solutions and a gelatin gel. The viscoelastic flow properties of dilute polymer solutions (gelatin, gelatin/color-coupler, polyacrylamide) were then investigated in the frequency range 5 Hz to 150 Hz at very small volume flow amplitudes. The results presented illustrate the suitability of the method. The results are also evaluated with regard to the stabilizing action of slightly viscoelastic gelatinous coating liquids in the high-speed coating process in the manufacture of photographic materials. 相似文献
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The system described for electrochemical analysis includes ensemble averaging, boxcar integration and background subtraction. A digital storage oscilloscope interfaced to a microcomputer provides these data-processing techniques for the differential pulse polarographic determination of molybdenum. The system is easily interfaced to the polarograph. An approximately four-fold improvement in the detection limit for molybdenum — to 2.7 × 10-4 ppm — was achieved by using a combination of ensemble averaging and background subtraction. 相似文献
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《Thermochimica Acta》1987,119(1):59-79
The undisturbed temperature equilibration of the vessel in an isoperibol calorimeter must follow an exponential time function. Any caloric effect within this vessel must cause a deviation of this function. A mathematical relation has been derived for linking the extent of this caloric effect and the integral of the temperature-time function.This algorithm has been utilized for a computer program capable for an automatic acquisition of the data of an appropriate digital temperature meter and for the automatic calculation of the calorimetric results.In two different calorimetric units these arrangements have been applied for the following determinations: -specific heat capacities of liquid samples -heats of chemical reactions -reaction rates -heats of vaporization of liquid samples. 相似文献
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Summary A high performance liquid chromatography system for the analysis of photosynthetic pigments is presented. The method employs an octadecylsilica stationary phase, a programmed quaternary mobile phase consisting of mixtures of methanol, acetonitrile, water and hexane, and a photodiode array detector. Carotenoids and chlorophylls are rapidly analysed in a single chromatographic separation. Thecis-trans isomers of most carotenoids are separated by this method. 相似文献
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An automatic data acquisition system was developed for two Mettler Vacuum Recording Thermoanalyzers, Model TA-I, using a Hewlett-Packard 9825S calculator. The interface with the thermoanalyzers is unique in the way that it is independent of and has a wider dynamic range than the six-channel strip chart recorder supplied with the instrument. The data acquisition system permits data from two TA-Is simultaneously in operation to be collected and stored in a magnetic tape cartridge.To facilitate rapid analysis of the acquired data, five computer programs were also developed for use with a Hewlett-Packard 9872A plotter. This data reduction system would (1) plot the thermograms (DTA, TG, DTG) including the % weight changes as a function of temperature or time, (2) label the thermograms, (3) record the experimental conditions, (4) correct the thermogravimetric data for effect due to buoyancy, if desired, (5) locate and mark the peak minima and maxima on DTA and DTG curves, and (6) tabulate the % weight change between two temperatures or time. 相似文献
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James S. Prell Jeremy T. O’Brien Evan R. Williams 《Journal of the American Society for Mass Spectrometry》2010,21(5):800-809
Three different commonly used infrared photodissociation (IRPD) spectroscopy acquisition and analysis methods are described, and results from these methods are compared using the same dataset for an extensively hydrated metal cation, La3+(H2O)36. Using the first-order laser-induced photodissociation rate constant as an IRPD intensity has several advantages over photodissociation yield and depletion/appearance methods in that intensities can be more directly compared with calculated infrared absorption spectra, and the intensities can be readily corrected for changes in laser power or irradiation times used for optimum data acquisition at each frequency. Extending IRPD spectroscopy to large clusters can be complicated when blackbody infrared radiative dissociation competes strongly with laser-induced photodissociation. A new method to obtain IRPD spectra of single precursor ions or ensembles of precursor ions that is nearly equivalent to the photodissociation rate constant method for single precursor ions is demonstrated. The ensemble IRPD spectra represent the “average” structure of clusters of a given size range, and this method has the advantage that spectra with improved signal-to-noise ratios can be obtained with no increase in data acquisition time. Results using this new method for a precursor ensemble consisting of La3+(H2O)35–37 are compared with results for La3+(H2O)36. 相似文献
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《Journal of Polymer Science.Polymer Physics》2017,55(10):804-813
We explore the physics of an atomic force microscopy (AFM) cantilever tip interacting with a generalized viscoelastic sample containing an arbitrary number of characteristic times, when the cantilever's base is driven with constant velocity toward the sample. This mode of operation, often called static force spectroscopy (SFS), can be harnessed to thoroughly analyze time‐dependent viscoelastic information frequently overlooked in experiments. We generalize the solution of previous authors who have studied the standard linear solid model, and offer a solution applicable to any linear viscoelastic model. This generalization is crucial for the prediction of the model's response over wide ranges of time‐scale. As a demonstration, successful predictions of harmonic functions (e.g., loss tangent) over a wide frequency range are obtained through analysis of simulated SFS results. In addition, we show that analysis through the generalized solution and previous expressions is no longer valid when the force does not grow linearly in time, so we also deliver an alternate route for extracting the viscoelastic information, which does not rely on the force linearity assumption. Despite the large amount of theoretical content (included for theoretical rigor's sake), the practical user can also benefit from the new procedures offered and the corresponding explanations. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 804–813 相似文献
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Mikhail M. Savitski Frank Fischer Toby Mathieson Gavain Sweetman Manja Lang Marcus Bantscheff 《Journal of the American Society for Mass Spectrometry》2010,21(10):1668-1679
Quantitative mass spectrometry-based proteomic assays often suffer from a lack of robustness and reproducibility. We here
describe a targeted mass spectrometric data acquisition strategy for affinity enriched subproteomes—in our case the kinome—that
enables a substantially improved reproducibility of detection, and improved quantification via isobaric tags. Inclusion mass
lists containing m/z, charge state, and retention time were created based on a set of 80 shotgun-type experiments performed under identical experimental
conditions. For each target protein, peptides were selected according to their frequency of observation and isobaric tag for
relative and absolute quantitation (iTRAQ) reporter ion quality. Retention times of selected peptides were aligned using similarity
driven pairwise alignment strategy yielding <1 min standard deviation for 4 h gradients. Multiple fragmentation of the same
peptides resulted in better statistics and more precise reporter ion based quantification without any loss in coverage. Overall,
24% more target proteins were quantified using the targeted data acquisition approach, and precision of quantification improved
by >1.5-fold. We also show that a combination of higher energy collisional dissociation (HCD) with collisional induced dissociation
(CID) outperformed pulsed-Q-dissociation (PQD) on the OrbitrapXL. With the CID/ HCD based targeted data acquisition approach
10% more quantifiable target proteins were identified and a 2-fold increase in quantification precision was achieved. We have
observed excellent reproducibility between different instruments, underlining the robustness of the approach. 相似文献
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Summary Several micro-techniques for the removal of solvent from dilute solutions of volatile compounds have been compared. Large
solute losses were experienced when the conventional blow-down technique was applied. Better yields could be obtained with
static evaporation procedures, as long as an effective reflux was maintained. However, careful optimization of the vessel
design and operating conditions is necessary. The most efficient volume reduction technique was shown to be chromatographic
evaporation. Quantitative recoveries were obtained for the compounds tested and the process was significantly faster than
static concentration. Moreover, operating conditions (gas flow, temperature) are less critical. With modifications, the principle
can be used for the concentration of large sample volumes down to a few microliters. 相似文献
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Target transformation factor analysis is applied to typical data from gas chromatography—mass spectrometry and solid-probe mass spectrometry to determine rapidly the number of components in unresolved or partially resolved peaks. This technique allows the detection of hidden impurities which often make interpretation or quantification impossible. The error theory of Malinowski is used to assess the reliability of the results. The totally automated system uses a commercially available g.c.—m.s. data system interfaced to a large computer, and the number of components under a peak can be determined routinely and rapidly. 相似文献
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John P. Elder 《Thermochimica Acta》1985,95(1):33-40
FORTRAN software is described which enables the generation of rate of weight change data (DTG) from percentage weight change measurements (TG), obtained under non-isothermal conditions. The program also transposes this information into the dimensionless extent and rate of reaction at unit temperature intervals by means of a cubic spline interpolation. A simple search routine identifies all DTG spikes in the thermogravimetric record, and the temperature and extent of reaction at which the rate attains its maximum value. This total information serves as input data for the kinetic analysis software to be discussed in part II of this communication. An example of the application of this program to the pyrolysis of bituminous coal is presented. 相似文献
16.
Conditions for masking sulfite ions with formaldehyde in the iodometric analysis of sulfur-containing mixtures are discussed.
The use of dilute formaldehyde solution for these purposes offers some advantages in comparison to the regularly used commercial
37% reagent. The solutions of the recommended concentrations (1–2% of formaldehyde) appeared to be stable for 6 years at least,
which simplified the analysis and reduced the consumption of the reagent. 相似文献
17.
Shi Qiao Xiaowei Shi Rui Shi Man Liu Ting Liu Kerong Zhang Qiao Wang Meicun Yao Lantong Zhang 《Analytical and bioanalytical chemistry》2013,405(21):6721-6738
The detection of drug metabolites, especially for minor metabolites, continues to be a challenge because of the complexity of biological samples. Imperatorin (IMP) is an active natural furocoumarin component originating from many traditional Chinese herbal medicines and is expected to be pursued as a new vasorelaxant agent. In the present study, a generic and efficient approach was developed for the in vivo screening and identification of IMP metabolites using liquid chromatography-Triple TOF mass spectrometry. In this approach, a novel on-line data acquisition method mutiple mass defect filter (MMDF) combined with dynamic background subtraction was developed to trace all probable urinary metabolites of IMP. Comparing with the traditionally intensity-dependent data acquisition method, MMDF method could give the information of low-level metabolites masked by background noise and endogenous components. Thus, the minor metabolites in complex biological matrices could be detected. Then, the sensitive and specific multiple data-mining techniques extracted ion chromatography, mass defect filter, product ion filter, and neutral loss filter were used for the discovery of IMP metabolites. Based on the proposed strategy, 44 phase I and 7 phase II metabolites were identified in rat urine after oral administration of IMP. The results indicated that oxidization was the main metabolic pathway and that different oxidized substituent positions had a significant influence on the fragmentation of the metabolites. Two types of characteristic ions at m/z 203 and 219 can be observed in the MS/MS spectra. This is the first study of IMP metabolism in vivo. The interpretation of the MS/MS spectra of these metabolites and the proposed metabolite pathway provide essential data for further pharmacological studies of other linear-type furocoumarins. 相似文献
18.
An improved methodology for adsorption characterization of unmodified and modified silica gels 总被引:2,自引:0,他引:2
An improvement in the adsorption characterization of the surface and structural properties of unmodified and modified mesoporous silica gels is presented. This improvement was achieved by selection of proper macroporous silica as the reference solid for adsorption characterization of porous silica gels. Experimental illustration is provided for unmodified and n-octyl-modified silica gels of different bonding density. The surface and structural properties of these silica gels were characterized by utilizing the standard adsorption data for both unmodified and octyl-modified LiChrospher Si-1000 macroporous silica gels. It was shown that the standard nitrogen adsorption data have an appreciable influence on the analysis of the pore size and surface properties of silica gels. This analysis can be improved by selecting the reference solid of the surface properties close to those of the silica gel studied. 相似文献
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An improved sodium dodecyl sulfate-polyacrylamide gel electrophoresis system for the analysis of membrane protein complexes 总被引:1,自引:0,他引:1
Membrane protein complexes such as the reaction center complexes of oxygenic photosynthesis or the complex I of mitochondira are composed of many subunit polypeptides. To analyze their polypeptide compositions by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), a wide range of molecular sizes has to be resolved, especially in the low molecular mass range. We have improved the traditional Tris/HCI buffer systems adopting a Tris/2-(N-morpholino)ethanesulfonic acid (MES) buffer system containing 6 M urea. This gel system was used with an 18-24% acrylamide gradient for the separation of polypeptides with molecular masses from below 5 kDa to over 100 kDa. This buffer system can also be applied to the usual uniform concentration of acrylamide gel and also to minislab gels. 相似文献