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  • 1
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand exchange ; Amino acid enantiomers ; DL-aspartic acid ; Pseudomonas dacunhae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of the D and L enantiomers of eighteen essential α amino acids has been investigated by ligand-exchange chromatography (LEC). The effect of column temperature on the retention times and resolution of individual amino acid enantiomers has been studied by varying the temperature from 25 to 50 °C for a mobile phase containing Cu2+ ions. By use of a temperature of 50 °C and Zn2+ in the mobile phase, eight of the eighteen amino acid enantiomers can be resolved sufficiently well for practical application. Only phenylalamine, tyrosine, and tryptophan can be separated by use of Ni2+ as complexation metal at 50 °C. LEC has been used to monitor the decarboxylation of racemic DL-aspartic acid byPseudomonas dacunhae. Analysis of DL amino acid enantiomers in different media was performed at column temperatures of 30 and 50°C by addition of 0.125 mM Cu2+ to the aqueous mobile phase. It was found that the analytical performance is most dependent on the identity of the metal used for complexation; the concentration of the metal was of secondary importance and the column temperature less important still.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 1230-1235 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This work designs and implements an inexpensive and simple double-crystal monochromator, which yields a high performance at a bending magnet x-ray beamline. A primary feature of the proposed monochromator is that the offset between the incident and monochromatic exit of the x-ray beam can be adjusted to cover a wide energy range with a short X–Y traveling stroke. Such a short range of X–Y strokes can reduce the monochromator's overall size and, also, increase the stability of motions. Meanwhile, in this monochromator, instead of using a complicated hardware linkage mechanism, a software program is developed to effectively control the X–Y stage for positioning the second crystal in a fixed exit configuration, alleviating mechanic motion errors to maintain the parallelism of the two crystals. The entire software control mechanical linkage offers a relatively inexpensive and simple assembly monochromator that is more flexible than the commercially available one. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: In this work, a 1 m long Sasaki-type elliptically polarizing undulator (EPU) prototype with 5.6 cm period length is used to examine the mechanical design feasibility as well as magnetic field performance. The magnetic field characteristics of the EPU5.6 prototype at various phase shifts and gap motion are described. The field errors from mechanical tolerances, magnet block errors, end field effects and phase/gap motion effects are analysed. The procedures related to correcting the field with the block position tuning, iron shimming and the trim blocks at both ends are outlined.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2013-08-31
    Description: A complete documentation of the software developed in the Communication and Signal Processing Laboratory (CSPL) during the period of July 1985 to March 1986 is provided. Utility programs and subroutines that were developed for a user-friendly image and speech processing environment are described. Additional programs for data compression of image and speech type signals are included. Also, programs for the zero-memory and block transform quantization in the presence of channel noise are described. Finally, several routines for simulating the perfromance of image compression algorithms are included.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NAS 1.26:180306 , TR-86-30 , NASA-CR-180306
    Format: application/pdf
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A 4-m-long elliptically polarizing undulator (EPU5.6) device with an Apple-II structure is installed in the Synchrotron Radiation Research Center storage ring. This is the longest EPU device with an Apple-II structure worldwide. The errors of the magnet construction and the assembly process are among the several factors that can degrade the spectral performance. This study describes the mechanical design concept and construction that reduce magnetic field errors to keep high performance of the magnet. The electron orbit distortion in various polarization radiation modes is discussed with reference to a global feedback system and a feed forward table with following gap and phase. The beam dynamic effects are also investigated when the phase and magnetic gap are changed. © 2002 American Institute of Physics.
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  • 6
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A special theoretical concept involving the harmonic magnetic-field measurement and analysis method using a fixed angle Hall probe was developed at the Synchrotron Radiation Research Center (SRRC) for measuring as well as analyzing the triple bending achromat magnets of the storage ring. The method can be used to simulate the harmonic magnetic-field calculation of the two-dimensional (2D) "magnet'' program. This method has a quite simple mechanism. The Hall plate was fixed at a 0° angle with respect to the horizontal plane of magnet to measure only the vertical field. Additionally, the 2D nonlinear least-square fitting was used to fit the mapping data so as to find the normal and skew multipole field strength. If necessary, the angle of Hall probe could be rotated 90° precisely for measuring the horizontal field. Consequently, the skew dipole field could be obtained. A real-time Hall-probe automatic magnetic-field measurement system was also developed for fulfilling the concept of the harmonic field measurement. Some special mapping trajectories for different kinds of magnets were discussed to match this special theoretical concept with the analysis methodology. This was done so as to obtain the reliable and accurate harmonic field strength. The accuracy and precision of the harmonic field strength measurement and analysis of this method being better than ±0.01% was confirmed by experimental results.
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  • 7
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: From the Gong-Shy-Tyan (GST) Stream and the Tanshui River, Taiwan, eels ranged from 5.53 cm t.l. (elvers) to 72.5 cm t.l. Anguilla japonica accounted for 93-99%, A. marmorata 1-7% and A. bicolor pacifica less than 1% of all eels caught. Mean eel lengths increased from 10 cm t.l. at the downstream sites to 50 cm t.l. at the upstream sites. Females made up 92.8% of the sex-determined eels. Population density, averaged approximately 0.14 eel m−2 (2.42 g m−2) and 0.25 eel m−2 (0.92 g m−2) in downstream sites of the GST and Tanshui River, respectively, and decreased substantially with upstream distance. Eels were rarely found in the heavily polluted and dam constructed areas in the midstream site of the Tanshui River.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A three-orthogonal-Hall-probe assembly with an `on the fly' mapping method has been developed to characterize an elliptically polarizing undulator (EPU). The underlying design concept is that it can measure the three real field components without any field correction under a reliable and synchronization measurement method. Therefore, the relative central position shift, orthogonal angle and the planar Hall effect error between the three Hall probes should be calibrated and readjusted. Experimental results demonstrate that this method can yield an r.m.s. reproducibility of 10 G cm for the three field components and 2 G for the peak field strength. Under precision conditions this system can completely measure the three on-axis field components within 2 min for a 4 m-long EPU.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1301-1311 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effects of various reaction variables on the stability of acrylic latices in a semibatch reactor were investigated by measuring the amount of coagulum formed and particle volume changes caused by limited flocculation. The amount of coagulum could be reduced signif-icantly with an increase in the level of sodium lauryl sulfate (SLS) in the monomer emulsion feed. An increase in the amount of SLS in the initial reactor charge resulted in an increase in the particle volume change due to limited flocculation later in the process. The larger the ratio of methyl methacrylate (MMA) to butyl acrylate (BA) in the copolymer, the greater the amount of coagulum produced. Both coagulum and particle volume change increased with an increase in the electrolyte concentration. Within the range studied (500-800 rpm), the agitation speed was not important to the coagulation process. Experimental data also indicated that the polymer particles could lose their stability rapidly above 40% total solids content because of the crowding effect. © 1996 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 989-1001 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The stability of latex particles in the semibatch emulsion polymerization of butyl acrylate (BA) in the presence of 0-10% acrylic acid (AA) was investigated. The amount of coagulum (i.e., large flocs caused by intensive coagulation) can be greatly reduced by an increase in the concentration of sodium lauryl sulfate (SLS) in the monomer emulsion feed. On the other hand, increasing the concentration of SLS in the initial reactor charge can result in an increase in the percentage of the particle volume change (i.e., a measure of the degree of limited flocculation) later in the process. Both the scrap and percentage of the particle volume change increase with an increase in the electrolyte concentration. Both the coagulation and secondary nucleation process can result in a significant deviation from the Novak model. Experimental data also show that latex particles comprising pure BA can lose their stability rapidly at higher total solids content because of the crowding effect. Incorporation of only 5% AA into the emulsion polymers greatly improves the latex stability. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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