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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Insect Biochemistry 19 (1989), S. 269-276 
    ISSN: 0020-1790
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Horseradish peroxidase (HRPO) was used as a probe to quantitate aflatoxin B1 by a homogeneous immunoassay. The conjugation of AFB1 to HRPO resulted in 54% loss of enyzme activity. In the presence of AFB1 specific antibodies, the HRPO-AFB1 conjugate showed reversal of its lost enzyme activity by 12%. This positive modulatory effect of antibody on the enzyme activity was used as an analytical tool to quantitate AFB1. The homogeneous assay carried out with free AFB1 and HRPO-AFB1 conjugate in the presence of antibodies indicated poor linearity as compared to the heterogeneous assay. It was observed that the number of HRPO-lysine residues involved in AFB1 conjugation were 6–8. The low level of modulation of enzyme activity by antibody with respect to HRPO-AFB1 conjugate, could possibly be attributed to the limited number of lysine residues in the HRPO molecule and its proximity to the active site of the enzyme. Thus, HRPO was found to be limiting as an enzyme with respect to the homogeneous enzyme immunoassay for AFB1 analysis. The antibodies raised were specific for AFB1, and showed excellent linearity even at high dilution for the detection of AFB1 by ELISA indicating that antibodies per se were not the limiting factor.
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  • 3
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Abstract We have deduced the steady-state lithospheric geotherm at c. 1 Ga in the south Indian shield area using the available data on the concentration of radioactive elements, and the P-T conditions of Proterozoic mantle xenoliths in the south Indian kimberlites as constraints. The geotherm was adjusted back to 2.5 Ga by keeping the surface temperature constant and calculating the temperature change at the top of convecting upper mantle. The reduced or mantle heat flux, which was treated as an adjustable parameter, was 20.9–21.3 mW/m2 at 1–2.5 Ga. Comparison of the calculated steady-state geotherm with the available P-T data of the Archaean (c. 2.5 Ga) charnockites and granulites from southern India suggests that the granulite facies metamorphism in this region had resulted from a major thermal perturbation, which was c. 400° C at 25 km.Seismic tomographic and gravity data essentially preclude any significant magma underplating of the granulitic crust in southern India. Previous workers have suggested that the formation of charnockites in this region was associated with copious CO2 influx from a deep-seated source, possibly the mantle. In this work, we have evaluated both the transient and steady-state thermal effects of the heat convected by CO2 outgassing from upper mantle. It is shown that the thermobarometric array of charnockites and granulites can be produced by the convective perturbation of the steady-state geotherm, and that a flux of CO2 of ±90 mol/m2 yr (corresponding to Darcy velocity of ±0.30 cm/yr) for a period of ±30 Ma was needed to produce the required perturbation. This is c. 150 times the average CO2 flux through the tectonically active area of the Earth's crust at the present time. There is, however, an uncertainty of a factor of 3 in this value.Seismic tomographic and gravity data independently suggest thickening of the crust beneath the granulite terrane compared with the adjacent Dharwar craton. This suggests thermal perturbation due to overthrusting as a major potential cause for the granulite facies metamorphism in south India. Overthrusting of a 30–35-km-thick thrust block was needed to produce the required thermal effect. The estimated thickness of the original crust from geobarometric and seismic tomographic data south of the orthopyroxene isograd or ‘transition zone’is compatible with the emplacement of a thrust block of this magnitude. However, the latter fails to match the estimated pre-uplift crustal thickness at the transition zone, if it is assumed that the crust has not thinned by non-erosional processes since the Archaean. Thus, we propose a combination of overthrusting and CO2 fluxing from a deep-seated source as the cause for the formation of charnockites in this zone. The required focusing of CO2 in this case is c. 40% of that estimated in the model where CO2 fluxing was considered to be the sole reason for thermal perturbation. This combined thrusting—CO2 fluxing model also helps explain the development of patchy charnockites in the transition zone from amphibolite facies rocks.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-0972
    Keywords: Aflatoxin ; Aspergillus ; coconut milk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Most agricultural commodities are susceptible to Aspergillus sp. infestation and aflatoxin elaboration. A simple test-tube screening procedure using fresh coconut milk agar medium (CMAM), for identifying toxigenic strains of Aspergillus sp., based on u.v. fluorescence (365 nm) and visual detection has been proposed and evaluated.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-1650
    Keywords: Aquifer ; water table ; transient recharge ; drain ; analytical solution ; prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract Recharging of aquifers due to irrigation, seepage from canal beds and other sources leads to the growth of water table near to the ground surface causing problems like water logging and increase of salinity in top soils in many regions of the world. This problem can be alleviated if proper knowledge of the spatio — temporal variation of the water table is available. In this paper an analytical solution for the water table fluctuation is presented for a 2-D aquifer system having inclined impervious base with a small slope in one — direction and receiving time varying vertical recharge. Application of the solution in estimation of water table fluctuation is demonstrated with the help of an example problem.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Competing ortho interactions, involving the C=X and the ortho-methyl substituent on the 3-phenyl moiety, resulting in the eliminations of ·CH3 and ·OH/·SH from the molecular ions of 2-substituted-3-(2-methylphenyl)-4(3H)-quinazolinones and their thio analogues, were observed. An intramolecular aromatic substitution of the heteroatom of C=X at the ortho-carbon of the 3-phenyl moiety ejecting the methyl group and a hydrogen transfer from the same ortho-methyl substituent to the heteroatom of C=X resulting in the expulsion of ·XH are envisaged for the dual ortho interaction. Another expected fragmentation process observed in these compounds is the transfer of the aryl group from the 3-position of the heterocycle to the heteroatom of C=X leading to the elimination of ArX· from the molecular ions. The proposed fragmentation processes and the ion structures are supported by high-resolution data, B/E and B2/E linked-scan spectra, collisionally activated decomposition B/E spectra and deuterium isotopic labelling.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A cycloreversal reaction, leading to aroyl cations, is the major process in 2-aryl-4H-3,1-benzoxazin-4-ones under electron impact conditions. The ortho interaction of the methoxy and the nitro groups in the 2-phenyl moieties in these compounds present the most abundant ions at m/z 119 and 134, respectively, in their mass spectra as a result of the transfer of a hydrogen atom from the former and an oxygen atom from the latter to the imine nitrogen of the heterocycle. The ion structures and the mechanisms for the proposed fragmentations are based on high-resolution data, B/E and B2/E linked-scan spectra, collision-activated decomposition-B-/E linked-scan spectra and deuterium labelling.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: N-(2-Propynyl)anilines undergo amino-Claisen rearrangement to a minor extent in the ion source, losing a molecule of HCN under electron impact conditions. However, metastable molecular ions with energies closer to threshold undergo Claisen rearrangement giving rise to more abundant [M - HCN]+· ions in the first field-free region. Loss of a hydrogen from the molecular ion gives rise to the base peak in the mass spectrum of N-(2-propynyl)aniline. The hydrogen that is expelled for the formation of the [M - H]+ ion is observed to be from the amino nitrogen, propargylic carbon and the ortho-carbon of the ring. The last process leads to a cyclic fragment involving intramolecular aromatic substitution. Double oxygen migration from the nitro group to the triple bond, due to the ortho effect, yields an abundant ion at m/z 105 in N-(2-propynyl)-o-nitroaniline. The proposed fragmentation pathways and ion structures are substantiated by high-resolution data, B/E and B2/E linked-scan spectra, collisionally activated dissociation-B/E linked-scan spectra and deuterium isotopic labelling.
    Additional Material: 4 Ill.
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  • 10
    ISSN: 1573-1650
    Keywords: analytical solution ; ground-water ; recharge basin ; transient recharge ; water-table
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract An analytical solution of the linearized Boussinesq equation is developed to predict the formation of a ground-water mound in an aquifer system in response to localized time-varying recharge. The recharge is applied from a centrally located circular basin. The solution is obtained using an eigenvalue-eigenfunction method. The solution for a constant recharge rate is shown as a special case of the solution for a time-varying recharge rate. Application of the solution to predict ground-water mound formation is demonstrated by a numerical example. Effects of variation in the rate of reachrge, size of recharge basin and the saturated hydraulic conductivity on the growth of the water-table are also investigated.
    Type of Medium: Electronic Resource
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