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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 4393-4397 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A procedure for operating an Eigler-style, low temperature scanning tunneling microscope (STM) at variable temperatures has been developed. A critical exchange gas pressure regime was found to allow for controlled variation of the STM temperature while it is encapsulated in a liquid helium Dewar. The sensitivity of various parameters to the ability to generate stable variable temperatures above 4 K is discussed. © 2001 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 54 (1992), S. 120-123 
    ISSN: 1432-0630
    Keywords: 72.70 ; 73.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We report on temperature (77 to 300 K) and voltage dependent low frequency (100 Hz to 100 kHz) noise behavior of InGaAs/InP photodiodes in non-equilibrium steady state. In addition to common white, 1/f, and Lorentz noise we are able to observe for the first time minima and maxima in the photocurrent noise spectra. The recombination of a pair of free carriers through a recombination center at the heterointerface provides the correlation between the electron and hole ensembles necessary to explain the observed noise reduction.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 50 (1997), S. 569-586 
    ISSN: 1572-8943
    Keywords: crystal structure ; metal(II) picolinate and quinaldinate ; thermal degradation of imidazole and pyrazole complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Complexes of the type M(Pa)2(HAz)2 and M(QA)2(HAz)2 (M=cobalt(II) and nickel(II); HPa=picolinic acid, HQa=quinaldic acid; HAz=azoles like imidazole (Him), pyrazole (HPz), benzimidazole (HBzIm) etc.) show a similar thermal behaviour. In the first step of decomposition the corresponding azolinium picolinates or quinaldinates (H2AzPa, H2AzQa) are split off with formation of polymeric mixed ligand complexes M(Pa)(Az) or M(Qa)(Az). X-ray analysis of Co(Qa)2(HBzIm)2 XIIIa illustrates a proton transfer and a subsequent thermal removal of benzimidazolinium quinaldinate (H2BzImQa): Hydrogen bridges from pyrrole nitrogen of the benzimidazole to the non-coordinated oxygen of the quinaldinate predetermine the thermal initiated proton transfer. The high volatility of the heterocyclic acids and the nitrogen coordination are responsible for the formation of the mixed ligand complex Co(Qa)(BzIm) XIVa. Exceptions are the complexes M(Pa)2(HPz)2 XIa-b and M(Qa)2(HIm)2 XVIIa-b. Pyrazole is eliminated from the complexes XIa-b with formation of the solvent-free inner complex M(Pa)2 XIIa-b. From compounds XVIIIa-b quinaldic acid or their decomposition products are split off and a high temperature modification of M(Im)2 XVIIIa-b is formed at elevated temperature. XVIIIa-b are decomposed to the cyanides M(CN)2 similarly to the thermal behaviour of Cu(Im). In the first step the thermal degradation of imidazole and pyrazole adducts of copper(II) picolinates and quinaldinates is characterized by the elimination of azoles. The reason for this thermal behaviour is the weaker coordination of the azole heterocycles in copper chelate compounds.
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  • 4
    ISSN: 1432-1858
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Technology
    Notes: Abstract  Microsystems recently have been introduced as tools for screening in modern chemistry, biochemistry and biology. It has been shown that new microsystems can be implemented in the biomedical laboratory by using the microsystemic approach for the sample carrier – the miniaturized microtiter plate (“the nanotiter plate”) – or the production of nanodroplets with ink jetters and to integrate those systems in macrodevices like xyz tables and detection devices like CCD-cameras. We show in this paper that decisive problems of the approach – the evaporation problem and the problem of chemical/biochemical/biological compatibility of the assays and the used materials can be solved successfully. It is possible to realize chemical synthesis in miniaturized flow systems and to perform isothermal amplification of RNA in silicon wafers. Furthermore real high throughput screening with in vivo systems can be performed and all relevant parameters as evaporation, pipetting and detection can be controlled on reasonable time scales.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 239-253 
    ISSN: 1572-8943
    Keywords: complexes ; coordination chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Das Zersetzung Verhalten der Komplexverbindungen vom Typ C0D2I2 (P = acetylaceton, Benzoylaceton;I = Imidazol oder Derivate) erfolgt stufenweise. Im Falle vonD = Acetylaceton erfolgt zuerst eine Eliminierung von Acetylaceton wärend beiD = Benzoylaceton zuerst ein Heteroligand eine Abspaltung erfährt. Bei einer unsubstituiertenΒ-Position von Nickelacyclen des Typs (bipy)Ni(CH2CH2CH2COO) erfolgt eine thermisch induzierteΒ-Hydrideliminierung unter Ringspaltung und Freisetzung von CO2. Im Gegensatz zur hohen thermischen Stabilität des Trimesityl Aluminium erfahren die Zwischenverbindungen Almes2Cl und AlmesCl2 mit abnehmenden Mesityl- bzw. zunehmenden Chlorgehalt einen wessentlich früheren thermischen Zerfall. Bei zunehmenden Kovalenzgrad ist hier ein Einfluss der veränderten Polarisation anzunehmen. Der thermische Abbau der prinzipiell wasserhaltig kristallisierenden Nickelchelate von alkylsubstituierten Chinolin-8-ol beginnt jeweils mit der Dehydratisierung. In Abhängigkeit von der Kettenlänge und der Position der Substitution am Chinolin schliesst sich der thermische Abbau der Chelatliganden ein- bzw. mehrstufig an.
    Notes: Abstract The behaviour of complexes of the type MeD2I2 (Me=Co,D = acetylacetone or benzoylacetone,I = imidazole and derivatives in the course of the stepwise thermal degradation is different. In the case ofD = acetylacetone in the first step acetylacetone is split off. At D = benzoylacetone the decomposition starts with the partial elimination of the heterocyclic ligands. InΒ-position unsubstituted nickelacyclic complexes from type (bipy)Ni(CH2CH2CH2COO) decompose by a reductive elimination and separating of CO2 forming a ‘(bipy)Ni’-intermediate. A single reductive decoupling is hindered by blocking up theΒ-position. Opposite to the high thermal stability of the trimesityl aluminium the intermediates Almes2Cl and AlmesCl2 show with decreasing amounts of mesityl groups and increasing content of halogene, respectively, a significant decreasing thermal stability. The thermal degradation of nickelchelates of alkylsubstituted chinolin-8-ol starts with the dehydration followed by a different separation of the ligands as a function of the chain-length and the position of the substituents of the ligands.
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  • 6
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We analyze the dependence of heavy quark free energies on the baryon chemical potential μb in 2-flavor QCD by performing a 6th order Taylor expansion in the chemical potential which circumvents the sign problem. The bare quark mass at $\hat m / T = 0.4$ corresponds to a pion mass of about 770 MeV and is thus not in the range of physical quark masses but the quark mass dependence is known to be small above Tc. At Nτ = 4 the lattices are coarse, however, we are using improved (p4 staggered) fermions. The Taylor expansion coefficients of color singlet and color averaged free energies are calculated and from this the expansion coefficients for the corresponding screening masses are determined. We find that for small μb the free energies of a static quark-antiquark pair decrease in a medium with a net excess of quarks and that screening is well described by a screening mass which increases with increasing μb. The μb-dependent corrections to the screening masses are well described by perturbation theory for T ≳ 2Tc. In particular, we find for all temperatures above Tc that the expansion coefficients for singlet and color averaged screening masses differ by a factor 2.PACS. 11.15.Ha, 11.10.Wx, 12.38Gc, 12.38.Mh
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 492 (1982), S. 52-62 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Behaviour of Cobalt(II) and Iron(III) in Case of Liquid-liquid Extraction by Pyridyl Substituted Benzene SulfonamidesPyridyl substituted benzene sulfonamides N 3 NHSO2R and N 2 NHSO2R which may be used as models of sulfonamide based metal extractants (LIX 34 et. al.) were studied as to their coordinative behaviour towards cobalt(II) and iron(III).The structure of Co(N 3 NSO2R)2 is distorted tetrahedral. Considering bond lengths and angles π-backdonation between cobalt and the nitrogen atoms is indicated which creates a higher effective charge on the central atom than in normal cobalt(II) complexes. Therefore, when observing normal conditions, Co(N 3 NSO2R)2 is not oxidized but reduced. Co(N 2 NSO2R)2 is a sulfonamide bridged tetramer with pentacoordinate cobalt(II).Iron(III) forms the low-spin complex salts [Fe(N 3 NHSO2R)2 (N 3 NSO2R)](NO3)2 · xH2O and [Fe(N 2 NHSO2R)2(N 2 NSO2R)](NO3)2 · xH2O which are insoluble in organic solvents. This is the reason why the copper(II)-iron(III) separation by sulfonamide based metal extractants proceeds without problems.
    Notes: Als Modelle für die in der Patentliteratur empfohlenen Metallextraktionsmittel auf Sulfonamidbasis (LIX 34 u.a.) werden pyridylsubstituierte Benzensulfonamide N 3 NHSO2R und N 2 NHSO2R auf ihr komplexchemisches Verhalten gegenüber Cobalt(II) und Eisen(III) untersucht.Co(N 3 NSO2R)2 hat eine stark verzerrte tetraedrische Struktur. Auf Grund der Strukturdaten wird eine π-Rückgabebindung vom Cobalt zum Amidstickstoff diskutiert, die eine gegenüber normalen Cobalt(II)-Komplexen erhöhte effektive Ladung des Zentralatoms erzeugt. Deshalb gelingt es unter normalen Bedingungen nicht, Co(N 3 NSO2R)2 zu oxidieren, wohl aber zu reduzieren. Co(N 2 NSO2R)2 ist tetramer, über Sulfonamidbrücken wird die Koordinationszahl 5 erreicht.Eisen(III) bildet die Komplexsalze [Fe(N 3 NHSO2R)2(N 3 NSO2R)](NO3)2 · xH2O und [Fe(N 2 NHSO2R)2(N 2 NSO2R)](NO3)2 · xH2O, die zum Low-Spin-Typ gehören und in organischen Lösungsmitteln nicht löslich sind. Darin liegt die Erklärung für den Befund, daß im Falle der Metallextraktionsmittel auf Sulfonamidbasis die Kupfer(II)-Eisen(III)-Trennung keine Probleme bringt.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 532 (1986), S. 65-72 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Redox Series Based on Transition Metal Complexes of Heterocyclic ArenesulfonylhydrazonesHeterocyclic bidentate arenesulfonylhydrazones (2-acetylpyridine-p-toluenesulfonylhydrazone = APSH—H, 2-acetylquinoline-p-toluenesulfonylhydrazone = ACSH—H) with transition metal ions afford tetrahedral 1,2-complexes MII(APSH)2 and MII(ACSH)2. In most cases the E-isomers of APSH- and ACSH- are coordinated, five-membered chelate rings are formed with the pyridine and hydrazone nitrogen atoms as donor atoms. In the complexes Zn(APSH)2 and Cu(APSH)2 probably the Z-isomer of APSH- is present with the pyridine and the sulfonylamide nitrogen atoms as a donor set, yielding a six-membered chelate ring. These proposals are based on the magnetic moments, the ligand field spectra, and the binding energies (ESCA).Normally the complexes MII(APSH)2 and MII(ACSH)2 are reduced in two reversible steps. For Fe(APSH)2 and Fe(ACSH)2 a third anodic wave, but for Cu(APSH)2 only one wave is observed. Relations between redox properties and structure of the new complexes are discussed, and the redox series are compared with that of the M(dipy)3n+-type complexes.
    Notes: Heterocyclisch substituierte, zweizählige Arensulfonylhydrazone (2-Acetylpyridin-p-toluensulfonylhydrazon = APSH—H, 2-Acetylchinolin-p-toluensulfonylhydrazon = ACSH—H) bilden mit übergangsmetallionen 1,2-Komplexe MII (APSH)2 und MII (ACSH)2 mit tetraedrischer Struktur. In den meisten Fällen koordinieren die Liganden APSH- und ACSH- als E-Isomere. Es entstehen fünfgliedrige Chelatringe mit dem Pyridin- und dem Hydrazonstickstoff als Donatoratomen. In den Komplexen Zn(APSH)2 und Cu(APSH)2 liegen wahrscheinlich die Z-Isomeren vor, die mit dem Pyridin- und dem Sulfonylamidstickstoff als Donatoratomen sechsgliedrige Chelatringe bilden. Die Strukturdiskussion wird auf der Basis der magnetischen Momente, der Ligandenfeldspektren und der ESCA-Daten geführt.Die Komplexe MII (APSH)2 und MII (ACSH)2 werden normalerweise in zwei reversiblen Stufen reduziert. Beim Eisen kommt eine anodische dazu, nur eine Stufe wird bei Cu(APSH)2 beobachtet. Es wurden Zusammenhänge zwischen Komplexstruktur und Redoxverhalten diskutiert und Vergleiche mit den Redoxserien von Chelaten des Typs M (dipy)3n+ gezogen.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 525 (1985), S. 179-191 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thermal Behavior and Thermochromism of Transition Metal Complexes of Pyridyl Substituted SulfonamidesThe thermal behavior of 1,2-complexes of nickel(II), copper(II) and cobalt(II) with pyridyl substituted sulfonamides (N1NHSO2PhH, N2NHSO2PhH, N3NHSO2PhH and N1SO2NHPhH) is studied between 20° and 600°C by TG, DTG, and DTA and more precisely characterized by identification of volatile decomposition products.In general the thermal decomposition starts by the reaction of one of the ligands with coordinated water or with the water vapor of air. Undecomposed N1NHSO2PhH and N3NHSO2PhH pass over to the vapor-phase, in the other cases the elimination is connected with a hydrolytic cleavage of the ligand. The thermal decomposition of Ni(N1NSO2PhH)2(NH3)2 is initiated by a transamidation.A study of Ni(N1NSO2PhH)2 demonstrates the influence of reaction conditions on the course of thermal decomposition. As far as milligram amounts are used, hydrolysis by the water vapor of air is dominating; but sulfur dioxide is eliminated when working in a preperative scale.The thermochromism of Ni(N2NSO2PhMe)2(H2O)2 goes back to the reversible transition of coordination water to lattice water. This is the first example of isomerism of the Lifschitz-type in the field of neutral chelates.
    Notes: Das thermische Verhalten von 1,2-Komplexen des Nickel(II), Kupfer(II) und Cobalt(II) mit pyridylsubstituierten Sulfonamiden (N1NHSO2PhH, N2NHSO2PhH, N3NHSO2PhH und N1SO2NHPhH)2 wird im Temperaturbereich von 20 bis 600°C mittels TG, DTG und DTA untersucht und durch die Identifizierung flüchtiger Abbauprodukte genauer charakterisiert.Die thermische Zersetzung beginnt im allgemeinen mit der Reaktion eines der Liganden mit dem Koordinationswasser oder dem Wasserdampf der Luft. N1NHSO2PhH, z. T. auch N3NHSO2PhH gehen dabei unzersetzt in die Gasphase über, in den anderen Fällen ist die Eliminierung mit einer hydrolytischen Spaltung der Liganden verbunden. Der thermische Abbau von Ni(N1NSO2PhH)2(NH3)2 wird durch eine Umamidierung eingeleitet.Am Beispiel von Ni(N1NSO2PhH)2 wird der Einfluß der Reaktionsbedingungen auf den Verlauf des thermischen Abbaus nachgewiesen. Beim Einsatz von Milligrammengen dominiert die Hydrolyse durch den Wasserdampf der Luft; bei präparativen Ansätzen dagegen die Eliminierung von Schwefeldioxid.Die Thermochromie des Komplexes Ni(N2NSO2PhMe)2(H2O)2 geht auf den reversiblen Übergang von Koordinationswasser in Gitterwasser zurück. Damit ist der Nachweis von Isomeren des Lifschitz-Typs auch für den Fall von Innerkomplexen erbracht.
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  • 10
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Azomethine and Oxime Groups as Constituents of Chelating Sulfonamides and Their Specific Influence on the Structure of 3d-Element ComplexesBidentate azomethine or oxime substituted sulfonamides with the donor set Nsp2\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm N}\limits^ \ominus $\end{document}N (SI—H, SA—H, TABO—H, OAS—H, D—H) form neutral 1,2-complexes which are stable to oxidation. The structure of the cobalt(II) compounds remarkably depends on the type of the ligand. The oximes yield planar low-spin complexes, but the azomethines tetrahedral high-spin ones, Evidently the planar species are stabilized by a system of intramolecular hydrogen bonds including the hydroxy groups of the oxime ligators.In the octahedral chelates Ni(PCSI)2 and Co(PCSI)2 p-toluensulfonamido-o-phenylene-2-pyridine aldimine (PCSI—H) has the function of a tridentate ligand, but is only bidentate in Fe(PCSI)2 and Mn(PCSI)2. In the latter case no coordination of the sulfonamido group is observed which is normal for iron(II) and manganese(II).The tricyclic tetradentate ligend bis[o-(p-toluenesulfonamido)benzophenonen]-ethylendiimirie (SBEI-2) forms the planar chelate Ni(SBE1);in Co(SBE1) und Cu(SBE1) the coordination sphere is tetrahedrally distorted.The discussion of the molecular structure of the new complexes is basod on VIS/NIR spectra, polarographic half-wave potentials, ESCA data, and the ESR spectra of some copper(II) complexes.
    Notes: Potentiell zweizählige azomethin- bzw. oximsubstituierte Sulfonamide mit dem Donatoratomsatz Nsp2\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm N}\limits^ \ominus $\end{document}N (SI—H, SA—H, TABO—H, OAS—H, D—H) bilden mit Cobalt(II), Nickel(II) und Kupfer(II) neutrale, oxidationsstabile 1,2-Komplexe. Die Struktur der Cobalt(II)- und Nickel(II)- Verbindungen hängt deutlich vom Liganden ab. Die Oxime ergeben durchweg planare Low-spin-Komplexe, die Azomethine dagegen tetraedrische High-spin-Komplexe. Die planaren Species werden durch intramolekulare Wasserstoffbindungssysteme stabilisiert, die nur im Falle der oximhaltigen Liganden möglich sind.p-Toluensulfonamido-o-phenylen-2-pyridinaldimin (PCSI—H) fungiert in den oktaedrischen Komplexen Ni(PCSI)2 und Co(PCSI)2 dreizählig, in der tetraedrischen Verbindungen Mn(PCSI)2 und Fe(PCSI)2 dagegen nur zweizählig, da sich die Sulfonamidgruppierung nicht an der Koordination beteiligt. Der tricyclisch vierzählige Ligand Bis[o-(p-toluensulfonamido)benzophenon-ethylendiimin(SBEI—H2)] bildet den planaren Komplex Ni(SBEI); in Co(SBEI) und Cu(SBEI) ist die Koordinationsphäre tetraedrisch verzerrt.Es werden die VIS/NIR-Spektren, polarographische Halbstufenpotentiale, ESCA-Daten und die ESR-Spektren einiger Kupfer(II)-Komplexe mitgeteilt und als Basis der Strukturdiskussion benutzt.
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