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  • 1
    Electronic Resource
    Electronic Resource
    Use of derived derivative thermogravimetric curves in the compositional study of two-component oxide systems (1978)
    Springer
    Journal of thermal analysis and calorimetry 13 (1978), S. 499-508 
    Details
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé Les méthodes thermogravimétriques (TG) permettent de suivre les réactions entre deux oxydes lorsque celles-ci s'accompagnent d'une variation pondérale et conduisent à la formation de composés nouveaux. Cependant, lors de la préparation des catalyseurs, les matériaux de départ ne sont pas, en général, des oxydes. Les méthodes les plus couramment employées sont la coprécipitation ou le malaxage des oxydes précipités. Les courbes TG et TGD des mélanges sont alors de nature complexe, pour diverses raisons, parmi celles-ci la formation de composés nouveaux. L'interprétation de la courbe TGD conventionnelle d'un tel prélèvement et l'identification des domaines de température correspondant à une activité thermique nouvelle quelconque, présentent des problèmes. On propose dans cet article d'utiliser la dérivée de la courbe thermogravimétrique dérivée pour de telles études. Cette courbe indique les différences entre le comportement thermique expérimental du composite et son comportement théorique calculé à partir de celui de ses constituants. Les régions oú une activité thermique nouvelle se manifeste sont faciles à déceler et à interpréter. Les deux systèmes suivants sont décrits: MgO-Cr2O3 et MgO-Fe2O3.
    Abstract: Zusammenfassung Reaktionen zwischen zwei Oxiden, welche unter Gewichtsänderungen zur Bildung neuer Verbindungen führen, können durch TG-Methoden untersucht werden. Jedoch sind bei der Herstellung von Katalysatoren die Ausgangsstoffe in den meisten Fällen keine Oxide. Die üblichen Methoden der Mitfällung oder des Knetens der gefällten Oxide werden eingesetzt. In solchen Fällen sind die TG- und DTG-Kurven der Zusammensetzungen aus verschiedenen Gründen von komplexer Art, eingeschlossen die Bildung neuer Verbindungen. Die Deutung der konventionellen DTG-Kurve einer solchen Probe und die Identifizierung der Temperatubereiche neuer thermischer Effekte stellt in diesem Falle Probleme dar. Für solche Untersuchungen wird der Einsatz einer derivierten DTG-Kurve, wie im Artikel beschrieben, vorgeschlagen. Diese Kurve zeigt die Differenzen zwischen dem experimentellen thermischen Verhalten der Zusammensetzungen gegenüber dem theoretischen thermischen Verhalten, das aus seinen Bestandteilen errechnet worden ist. Die Bereiche einer neuen thermischen Aktivität können leicht entdeckt und gedeutet werden. Zwei Systeme, MgO-Cr2O3 und MgO-Fe2O3 werden beschrieben.
    Notes: Abstract Reaction between two oxides leading to the formation of a new compound through a change in weight can be studied by TG methods. However, for catalyst preparations, in most of the cases the starting materials are not oxides. The more common methods of coprecipitation or kneading of the precipitated oxides are employed. In such cases the TG and DTG curve of the composites are of a complex nature for several possible reasons including the formation of new compounds. The interpretation of the conventional DTG curve of such a sample and identification of temperature regions for any new thermal activity thus presents problems. For such studies the use of a derived derivative thermogravimetric curve is suggested as described in this paper. This curve indicates the differences between the experimental thermal behaviour of the composite vis-a-vis theoretical thermal behaviour of the composite computed from the thermal behaviour of its constituents. The regions of a new thermal activity can be readily located and interpretated. Two systems are described, MgO-Cr2O3 and MgO-Fe2O3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01912389
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetometer Array Study in North-Northeast Brazil: Conductivity Image Building and Functional Induction Modes (1998)
    Springer
    Pure and applied geophysics 152 (1998), S. 349-375 
    Details
    ISSN: 1420-9136
    Keywords: Key words: Electromagnetic induction, magnetovariational fields, geomagnetic deep sounding, conductivity anomalies, intracratonic basin, magmatic activity.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —Magnetovariational fields recorded by an array of magnetometers in the equatorial region of north-northeast Brazil are analyzed to infer the configuration of internal induced currents in and around the extensive intracratonic Parnaíba basin. Only nighttime magnetovariational fields were used because of the prevailing uniform source field conditions. For periods exceeding 40 min. the vertical fields at all inland sites are dominated by the effects of electric currents originating in the northeast, in the deep Atlantic Ocean. Below this period, although best developed in the 12–15 min. period range, the anomalous signatures are principally controlled by two distinct continental current paths. The first is associated with a N60°E trending graben-like structure in the southeastern part of the basin (named the Parnaíba Basin Conductivity Anomaly—PBCA) and the second appears as a subsurface sedimentary channel, from the NW corner of the array to the central part of the basin. This is named the LINK anomaly, as it connects the northwestern Marajó basin with the Parnaíba basin. While the PBCA is shown to highlight the importance of basement tectonics in the geological evolution of the Parnaíba basin, the LINK anomaly provides strong geophysical evidence of the direction of the sea intrusion into the region of the basin and possibly indicates the connectivity of the Parnaíba basin to the adjoining Amazon basin through the Marajó basin. Frequency and polarization dependence suggest that the induction response of individual structures is not determined by the local conductivity alone but also by their interconnectivity as well as by their linkage to the continental shelf and deep oceanic region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050158
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  • 3
    Electronic Resource
    Electronic Resource
    Phosphate sorption isotherms in relation to P nutrition of wheat (Triticum aestivum) (1996)
    Springer
    Nutrient cycling in agroecosystems 47 (1996), S. 99-106 
    Details
    ISSN: 1573-0867
    Keywords: dry matter yield ; fertilizer efficiency factor (C) ; maximum buffer capacity (MBC) ; maximum obtainable yield (MOY) ; modified Mitscherlich yield equation ; solution P concentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The phosphate sorption isotherms are needed to explain differential plant responses to P fertilization in soils. Laboratory and greenhouse experiments investigated the use of phosphorus sorption isotherms in relation to P fertilizer requirement of wheat in ten benchmark soils of Punjab, India. The modified Mitscherlich Equation (3) was used to describe plant response observed in different soils. Maximum obtainable yield (MOY) ranged from 11.6 g pot−1 in Gurdaspur (I) sandy clay loam to 7.0 g pot−1 in Nabha sandy clay loam. Response to P applied @ 25 mg P kg−1 soil was maximum (77%) in Bathinda sand and minimum in Chuharpur clay loam (33%). The response curvature varied from 3.74 × 10−2 in Nabha sandy clay loam to 4.43 × 10−2 in Kanjli sandy loam. The soil solution P required to produce optimum yield (90% MOY) varied from 1.61 µg ml−1 in Bathinda sand to 0.10 µg ml−1 in Sadhugarh clay. Dry matter yield obtained at 0.2 µg ml−1 solution P concentration ranged from 55% in Bathinda sand to 85% of MOY in Gurdaspur (II) clay loam. At the same solution P concentration (0.1 µg P ml−1), dry matter yield was 91% in Sadhugarh clay, 80% in Gurdaspur (II) clay loam and, 43% of MOY in Bathinda sand and eventually coincided with the decreasing maximum buffer capacity (MBC) in these soils. At the same level of sorbed P (100 mg P kg−1 soil) the yield was observed to be inversely proportional to MBC. The study, therefore, concludes that, soils should be grouped according to their P sorption characteristics and MBC before using critical soil solution P as a criterion for obtaining optimum yields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01991541
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  • 4
    Electronic Resource
    Electronic Resource
    Tropospheric vorticity responses to the solar magnetic sector structure and geomagnetic disturbances (1981)
    Springer
    Pure and applied geophysics 119 (1981), S. 893-900 
    Details
    ISSN: 1420-9136
    Keywords: Geomagnetic disturbance ; Solar magnetic sector ; Solar-weather relationship ; Vorticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The responses of the Vorticity Area Index (VAI) at 500 mb to large geomagnetic disturbances and to magnetic sector boundary crossings are evaluated for the periods 1947–57 and 1963–74, during which time the geomagnetic response to sector structure were known to be distinctly different. Results indicate that the nature of the VAI response to geomagnetic disturbances is markedly similar between the two subsets. The response does not vanish even when only those geomagnetic disturbances not related to sector boundary passage are used in the analysis, which suggests that enhanced geomagnetic activity can independently influence the lower atmosphere. Unlike the geomagnetic disturbance-related effects the sector-related effects have varied with time in a very complex manner. In view of this it is concluded that geomagnetic disturbances, whose effects have shown pronounced consistency, may prove a better solar signal in future sun-weather studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00878957
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  • 5
    Electronic Resource
    Electronic Resource
    Geomagnetic solar and lunar daily variations at Alibag, India (1984)
    Springer
    Pure and applied geophysics 122 (1984), S. 89-109 
    Details
    ISSN: 1420-9136
    Keywords: Solar daily variation ; Lunar daily variation ; Solar-cycle modulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Geomagnetic solar and lunar daily variationsS andL, at Alibag, India are derived, by the well-known Chapman-Miller method, from the series of homogeneous mean hourly magnetic data of the years 1932 to 1972. The data for all the three elements — declinationD and horizontal and vertical intensitiesH andZ — are analysed, by dividing the data suitably for a study of the seasonal variations, the effect of the changes in the solar and magnetic activities onS andL, the oceanic dynamo contribution toL, and their interactions with each other. The main results are as follows. (i) ForS the daily pattern and its seasonal progression conform to the type expected from a northern-hemisphere station. On the other hand, the amplitudes of all the four harmonics ofL systematically have higher values in winter, and inD andZ the harmonics show large phase differences between summer and winter. The pattern ofL in winter suggests that the lunar current system consists of a single set of vortices in the summer hemisphere rather than the conventional vortices, one set in each of the hemispheres. (ii) Solar-cycle modulation on the solar ranges as well as on the amplitudes of the first three harmonics ofS is greater than that expected solely from the increase in E-region conductivity, whereas the corresponding modulation onL is comparable to that on the E-region conductivity. (iii) With increasing magnetic activity the first harmonic ofS shows an increase, and the first three harmonics ofL indicate a general decrease, in amplitude. (iv) Of the variability inS 96%, but inL only 32%, is found to be accounted for by the combined effect of the variations in the solar and magnetic activities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00879651
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  • 6
    Electronic Resource
    Electronic Resource
    On the universal time component in the daily variation of the geomagnetic disturbance field (1974)
    Springer
    Pure and applied geophysics 112 (1974), S. 456-463 
    Details
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The magnitude of the universal time (UT) component in the daily variation of geomagnetic disturbance which depends on the position of the earth's magnetic axis relative to the sunearth system is evaluated at two low-latitude stations, Alibag in the northern hemisphere and Hermanus in the southern hemisphere. To provide better resolution on time scale, mean hourly values of horizontal intensity are used rather than indexK of magnetic activity. During solstices the UT component has a mean amplitude of 6.8 γ at Alibag and 3.0 γ at Hermanus with maximum contribution near the predicted time of 0430 UT in June and 1630 UT in December. It is found that the UT component makes a significant contribution to the daily variation of disturbance field during equinoxes but the part dependent on the angle between the earth's magnetic axis and the sun-earth line is found to be larger during September than in March, suggesting an asymmetry in the incident solar wind. This is possibly due to the varying heliographic latitude of the earth and the asymmetry in activity in the two hemispheres of the sun.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876153
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  • 7
    Electronic Resource
    Electronic Resource
    Sorption of phosphorus by the iron oxide-impregnated filter paper (Pi soil test) embedded in soils (1990)
    Springer
    Plant and soil 126 (1990), S. 287-294 
    Details
    ISSN: 1573-5036
    Keywords: extraction by embedding strips ; in situ evaluation ; iron oxide paper (Pi) strips ; moisture effect on P extracted ; Pi soil P test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Incubation experiments were carried out to evaluate the feasibility of extracting phosphorus from soil by embedding iron oxide-impregnanted filter paper strips (Pi strips) in soils having a wide range in pH, texture, and extractable-P contents. Under flooded conditions, the amount of P extracted by the Pi strips increased with the period of submergence and embedding time of the Pi strips. Under unsaturated conditions, the Pi strips were found to extract P from soils over a wide range in moisture conditions; however, keeping the soil at moisture level between saturation and field capacity was found to result in maximal sorption of P by the strips. An embedding time of 16 h was found to be adequate. Phosphorus extracted by embedding Pi strips in soil columns for 16 h at field capacity moisture level correlated significantly with P extracted by shaking the soil with 0.01 M CaCl2 solution and a Pi strip for 16 h in the laboratory (r=0.94**). The P extracted by embedding Pi strips correlated best with Bray 1 P in acid soils (r=0.97**) and with Olsen P in alkaline and calcareous soils (r=0.96**). The results of the studies demonstrate the feasibility of developing a nondestructive method of monitoring changes in plant-available P in situ under field conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012831
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of sulphur fertilization on the nitrogen-sulphur relationships in alfalfa (Medicago sativa L. Pers.) (1976)
    Springer
    Plant and soil 45 (1976), S. 75-80 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Distribution of different nitrogen and sulphur fractions and N:S ratios in alfalfa (Medicago sativa L. Pers.) without and with S fertilization has been studied with a green house experiment. With increasing rates of applied S, the concentrations of total N, protein N, total S, protein S and total soluble S in the plant increased but those of non-protein N fractions (total soluble N, amino acid N, amide N, nitrate N) decreased. Thus the adequate supply of S in alfalfa increases the protein synthesis by accelerating protein metabolism. Sulphur application narrowed total N:total S ratios and widened protein N:protein S ratios. The data indicate that one part sulphur was required for every 11 to 12 parts of nitrogen to insure maximum production of protein. re]19750305
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011130
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  • 9
    Electronic Resource
    Electronic Resource
    Thermoanalytical study of the solid state reaction between hydrated ZnO and Fe2O3 (1980)
    Springer
    Journal of thermal analysis and calorimetry 18 (1980), S. 5-13 
    Details
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé Les oxydes hydratés formés lors de l'addition du bicarbonate d'ammonium à une solution de Zn(NO3)2 et de Fe(NO3)2 suivie du séchage du précipité à 110°, sont l'hydroxy-carbonate de zinc(I) et le gel de l'oxyde de fer(III) (II). On a utilisé une nouvelle technique de thermogravimétrie en dérivation, ainsi que les méthodes d'ATD et TGD conventionnelles, pour étudier la réaction entre (I) et (II) dans le système à deux composants. Un mélange de (I) et de (II), soumis au broyage, donne environ 16 p.c. de ferrite de zinc «précurseur», tandis qu'un échantillon préparé par coprécipitation à partir de la solution des nitrates mixtes et séchage à 110°, en donne environ 70 p.c. La formation du spinelle de ferrite de zinc décrite comme ayant lieu, dans des cas similaires, à des températures faibles, paraît être en rapport avec la formation du «précurseur» ainsi qu'avec la réactivité et la température de la transformation de phase de Fe2O3.
    Abstract: Zusammenfassung Die durch Zugabe von Ammoniumbicarbonat zu einer Lösung von Zn(NO3)2 und Fe(NO3)3 und Trocknung des Niederschlags bei 110° gebildeten hydratisierten Oxide sind Zinkhydroxycarbonat (I) bzw. Eisen(III)oxidgel (II). Eine neue derivierte derivative thermogravimetrische Kurve wurde gemeinsam mit den konventionellen DTA und DTG Methoden zum Studium der Reaktion zwischen (I) und (II) in Zweikomponentensystemen eingesetzt. Das Gemisch von (I) und (II) ergibt beim Mahlen etwa 16% Zinkferrit »Prekursor«. In einer durch Mitfällung der gemischten Nitrate und Trocknung bei 110° erhaltenen Probe wurde fast 70 % »Prekursor« gebildet. Die Bildung von Zinkferritspinell, über dessen Entstehung in solchen Fällen bei niedrigen Temperaturen berichtet wird, scheint mit der Bildung des »Prekursors« verbunden zu sein, sowie mit der Reaktivität und der Phasenübergangstemperatur in Fe2O3.
    Notes: Abstract The hydrated oxides which are formed by the addition of ammonium bi-carbonate to a solution of Zn(NO3)2 and Fe(NO3)3, and drying the precipitates at 110° are zinc hydroxy carbonate(I) and iron(III) oxide gel(II), respectively. A new, derived derivative thermogravimetric curve along with conventional DTA and DTG methods have been used to study the reaction between (I) and (II) in two components system. A mixture of (I) and (II) subjected to grinding yields about 16% zinc ferrite ‘precursor’. In a sample prepared by coprecipitation from the mixed nitrate solution and drying at 110°, nearly 70% ‘precursor’ is formed. The formation of zinc ferrite spinel reported to take place at low temperature in such cases appears to be related with the formation of the ‘precursor’, and reactivity and phase transformation temperature in Fe2O3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01909448
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  • 10
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    Geophysical Constraints on the Seismotectonics of the Sikkim Himalaya (2014)
    Seismological Society of America (SSA)
    Details
    Publication Date: 2014-10-04
    Description: The role of transverse lineaments is often invoked in strain partitioning to generate strike-slip-dominated earthquakes in the Sikkim Himalaya, including the recent M w  6.9 earthquake of 18 September 2011. An integration of seismicity clusters and crustal structures in conjunction with gravity modeling helps to develop a unified seismotectonic model for the Sikkim Himalaya, where transverse lineaments appear to have little role in strain concentration. Instead, deflection of the arc normal slips by rigid eclogitized Indian crust in the 40–60 km depth range is the primary source to generate strike-slip-dominated, large-magnitude earthquakes. The clustering of relatively deep aftershocks and main event near the southern edge of the eclogitized lower crust is a clear manifestation of this deformation. This transcurrent deformation also reorients foliation planes in the low-velocity block immediately above to inflict anisotropy and promote strike-slip-dominated moderate-magnitude earthquakes in the 20–40 km depth range. The low-angle northeast-dipping detachment in the 10–12 km depth range forms a localized asperity that produces low-magnitude earthquakes beneath the Lesser Himalayan duplex. It is surmised that the competent and strong eclogitic layer in the lower crust serves as a repository of high stresses during an earthquake buildup cycle, wherein the fluid pressure in the fractured rock matrix above plays a key role in the earthquake generating process.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America (SSA)
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