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  • Articles: DFG German National Licenses  (290)
  • 2015-2019
  • 1995-1999  (290)
  • 1960-1964
  • 1925-1929
  • 1830-1839
  • 1996  (290)
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  • Articles: DFG German National Licenses  (290)
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  • 2015-2019
  • 1995-1999  (290)
  • 1960-1964
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 43 (1996), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . In vitro excystation of Spironucleus muris cysts, purified by sequential sucrose and Percoll gradients from mouse feces, was studied. Three in vitro excystation procedures, used for Giardia, were assessed to determine the most useful method. Excystation was monitored by light microscopy and subsequently characterized by transmission and scanning electron microscopy. Spironucleus muris excysted routinely at a level greater than 90% when induced in Hanks’ balanced salt solution containing sodium bicarbonate at pH 2.0 and transferred to Tyrodes’ salt solution as an excystation medium. Similarly, high rates of excystation were recorded after induction of S. muris cysts in 0.1 M potassium phosphate buffer (pH 7.0) with sodium bicarbonate and excystation in trypticase-yeast extract-iron medium (TYI medium) or phosphate-buffered saline. A lower rate and percentage of excystation were observed after induction of S. muris cysts in an aqueous hydrochloric acid solution (pH 2.0) followed by excystation in TYI medium. All excystation methods produced extremely active S. muris trophozoites with normal morphology. Nonexcysting S. muris cysts have a wall composed of an outer fibrous and an inner membranous portion. Following induction, numerous vesicles appeared in the peritrophic space. Excystation began by the cyst wall opening at one pole, and the anterior part of the trophozoite protruding from the cyst wall. The trophozoite emerged progressively from the cyst wall and the empty cyst wall appeared to collapse. Excysted trophozoites exhibited normal morphological features of S. muris trophozoites isolated from the mouse intestine.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: Gy mouse ; Inorganic phosphate ; Sodium-gradient-dependent phosphate transport ; Brush border membrane ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The X-linkedGy mutation is closely linked, but not allelic, toHyp and is characterized by rickets, hypophosphatemia, decreased renal tubular maximum for phosphate (Pi) reabsorption (TmP) and a specific reduction in renal brush-border membrane (BBM) Na+-Pi cotransport.Gy mice, like their normal littermates, respond to a low-Pi diet with an increase in BBM Na+-Pi cotransport, but fail to show an adaptive increase in TmP. Using an antibody raised against the NH2 terminal peptide of the rat renal-specific Na+-Pi cotransporter (NaPi-2) and a NaPi-2 cDNA probe, we examined the effect of theGy mutation and low-Pi diet (0.03% Pi) on NaPi-2 protein and mRNA abundance. The reduction in BBM Na+-Pi cotransport inGy mice (51 ± 5 % of normal,P 〈 0.05) was associated with a decrease in NaPi-2 protein (46 ± 12% of normal,P 〈 0.05) and mRNA abundance (76 ± 5%,P 〈 0.05). The low-Pi diet elicited a two- to three-fold increase in Na+-Pi cotransport in both normal andGy mice that was accompanied by a large increase in NaPi-2 protein (10.2-fold in normal and 16.9-fold inGy mice) and a modest increase in NaPi-2 mRNA (1.3-fold in both mouse strains,P 〈 0.05). The present data demonstrate that (1) the renal defect in BBM Pi transport inGy mice can be ascribed to a deficit in NaPi-2 protein and mRNA abundance, (2) both normal andGy mice respond to low Pi with an adaptive increase in NaPi-2 protein that exceeds the increase in Na+-Pi cotransport activity and NaPi-2 mRNA, (3) the adaptive increase in NaPi-2 protein and mRNA are not sufficient for the overall increase in TmP following Pi restriction.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2013
    Keywords: Key wordsGy mouse ; Inorganic phosphate ; Sodium-gradient-dependent phosphate transport ; Brush border membrane ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The X-linked Gy mutation is closely linked, but not allelic, to Hyp and is characterized by rickets, hypophosphatemia, decreased renal tubular maximum for phosphate (Pi) reabsorption (TmP) and a specific reduction in renal brush-border membrane (BBM) Na+-Pi cotransport. Gy mice, like their normal littermates, respond to a low-Pi diet with an increase in BBM Na+-Pi cotransport, but fail to show an adaptive increase in Tmp. Using an antibody raised against the NH2 terminal peptide of the rat renal-specific Na+-Pi cotransporter (NaPi-2) and a NaPi-2 cDNA probe, we examined the effect of the Gy mutation and low-Pi diet (0.03% Pi) on NaPi-2 protein and mRNA abundance. The reduction in BBM Na+-Pi cotransport in Gy mice (51 ± 5% of normal, P 〈 0.05) was associated with a decrease in NaPi-2 protein (46 ± 12% of normal, P 〈 0.05) and mRNA abundance (76 ± 5%, P 〈 0.05). The low-Pi diet elicited a two- to three-fold increase in Na+-Pi cotransport in both normal and Gy mice that was accompanied by a large increase in NaPi-2 protein (10.2-fold in normal and 16.9-fold in Gy mice) and a modest increase in NaPi-2 mRNA (1.3-fold in both mouse strains, P 〈 0.05). The present data demonstrate that (1) the renal defect in BBM Pi transport in Gy mice can be ascribed to a deficit in NaPi-2 protein and mRNA abundance, (2) both normal and Gy mice respond to low Pi with an adaptive increase in NaPi-2 protein that exceeds the increase in Na+-Pi cotransport activity and NaPi-2 mRNA, (3) the adaptive increase in NaPi-2 protein and mRNA are not sufficient for the overall increase in TmP following Pi restriction.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0044-2313
    Keywords: Gadolinium sesquihalide ; interstitial carbon units ; crystal structure ; electronic structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [Gd4(C2)](Cl, I)6, ein interstitiell stabilisiertes, heteroleptisches Gadoliniumsesquihalogenid[Gd4(C2)](Cl, I)6 erhält man aus CsI, Gd, GdCl3 und C2I4 in verschweißten Niob-Ampullen bei 1000/800°C in Form von schwarzen, glänzenden Nadeln. Die Kristallstruktur (tetragonal; P4/mbm; Z = 2; a = 1347,5(1); c = 1212,5(1) pm) ist ähnlich wie jene von Na[Mo4]O6 bzw. [Sc4B]Cl6. Trans-kantenverknüpfte [Gd6]-Oktaeder verlaufen parallel [001]. Sie enthalten interstitielle C2-Einheiten, Jedes dritte Oktaeder enthält fehlgeordnete C2-Einheiten, senkrecht zu jenen in den benachbarten [Gd6(C2)]-Oktaedern. Diese sind daher entlang der (pseudo)-C4-Achse gestaucht. Rechnungen zur elektronischen Struktur zeigen, daß insgesamt 13 Elektronen zur Auffüllung aller Metall-Metall-bindenden Zustände für eine „leere“ [Gd4]Cl6-Struktur nötig wären. Die Einlagerung der C2-Dimeren verändert die Bindungsverhältnisse in [Gd4(C2)]X6 (X = Cl, I) erheblich. Die formale Ladung von -6 der C2-Einheit wird durch das Aufsplitten der πg-Zustände reduziert, Gd—Gd und Gd—C-bindende Zustände werden besetzt und bindende dx2-y2-Orbitale kombinieren zu den am niedrigsten liegenden nicht besetzten Zuständen.
    Notes: [Gd4(C2)](Cl, I)6 is obtained from CsI, Gd, GdCl3 and C2I4 in sealed niobium containers at 1000/800°C as black, shiny needles. The crystal structure (tetragonal, P4/mbm, Z = 2, a = 1347.5(1), c = 1212.5(1) pm) is similar to that of Na[Mo4]O6 and [Sc4B]Cl6. It may be regarded as being built from octahedra sharing common trans edges running in the [001] direction. The octahedra contain C2 units as interstitials. Every third octahedron contains a disordered C2 unit perpendicular to those in the two neighboring [Gd6(C2)] octahedra and is therefore compressed in the direction of the (pseudo) C4 axis. Calculations of the electronic structure of an “empty” [Gd4]Cl6 structure reveals a total of 13 electrons necessary to occupy all metal-metal bonding states. The incorporation of a carbon dimer substantially alters the bonding conditions for [Gd4(C2)]X6 (X = Cl, I). The formal charge of -6 of the C2 unit is significantly reduced as πg states split up, Gd—Gd and Gd—C bonding states are occupied and bonding dx2—y2 orbitals combine to form the lowest unoccupied energy states.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 3425-3437 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The generation of harmonics by interaction of an ultrashort laser pulse with a step boundary of a plane overdense plasma layer is studied at intensities Iλ2=1017–1019 W cm−2 μm2 for normal and oblique incidence and different polarizations. Fully relativistic one-dimensional particle-in-cell (PIC) simulations are performed with high spectral resolution. Harmonic emission increases with intensity and also when lowering the plasma density. The simulations reveal strong oscillations of the critical surface driven by the normal component of the laser field and by the ponderomotive force. It is shown that the generation of harmonics can be understood as reflection from the oscillating surface, taking full account of retardation. Describing the oscillations by one or more Fourier components with adjustable amplitudes, model spectra are obtained that well reproduce the PIC spectra. The model is based on relativistic cold plasma equations for oblique incidence. General selection rules concerning polarization of odd and even harmonics depending on incident polarization are derived. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Reliable operation of discharges with negative central magnetic shear has led to significant increases in plasma performance and reactivity in both low confinement, L-mode, and high confinement, H-mode, regimes in the DIII-D tokamak [Plasma Physics and Controlled Nuclear Fusion Research 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. 1, p. 159]. Using neutral beam injection early in the initial current ramp, a large range of negative shear discharges have been produced with durations lasting up to 3.2 s. The total noninductive current (beam plus bootstrap) ranges from 50% to 80% in these discharges. In the region of shear reversal, significant peaking of the toroidal rotation [fφ(0)∼30–60 kHz] and ion temperature [Ti(0)∼15–22 keV] profiles are observed. In high-power discharges with an L-mode edge, peaked density profiles are also observed. Confinement enhancement factors up to H≡τE/τITER-89P∼2.5 with an L-mode edge, and H∼3.3 in an edge localized mode (ELM)-free H mode, are obtained. Transport analysis shows both ion thermal diffusivity and particle diffusivity to be near or below standard neoclassical values in the core. Large pressure peaking in the L mode leads to high disruptivity with βN≡βT/(I/aB)≤2.3, while broader pressure profiles in the H mode gives low disruptivity with βN≤4.2. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 2197-2202 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Etching of SiO2 with CF4 in three types of high density–low pressure (5×1011 cm−3, 1–10 mTorr) etch tools: electron cyclotron resonance (ECR), inductively coupled (ICP), and helicon (HRF) is described. Although the physical processes that produce the plasma in the three types of sources are quite different, the etch rate processes are identical when viewed from the wafer sheath boundary. Measurements demonstrate that if sufficient fluorine is present, the etch rate limiting step depends only on the ion energy flux to the wafer, rather than on the details of the chemical species. Etch rate control depends only on the wafer bias power. Experimental results are device independent so the etch rate in high density–low pressure plasma sources does not depend on the plasma source power. Major differences in tool etch rate characteristics are more likely determined by tool wall material (and wall chemistry) and tool geometry rather than the physical process that is used to produce the plasma. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The confinement and the stability properties of the DIII-D tokamak [Plasma Physics and Controlled Nuclear Fusion Research 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. 1, p. 159] high-performance discharges are evaluated in terms of rotational and magnetic shear, with an emphasis on the recent experimental results obtained from the negative central magnetic shear (NCS) experiments. In NCS discharges, a core transport barrier is often observed to form inside the NCS region accompanied by a reduction in core fluctuation amplitudes. Increasing negative magnetic shear contributes to the formation of this core transport barrier, but by itself is not sufficient to fully stabilize the toroidal drift mode (trapped-electron-ηi mode) to explain this formation. Comparison of the Doppler shift shear rate to the growth rate of the ηi mode suggests that the large core E×B flow shear can stabilize this mode and broaden the region of reduced core transport. Ideal and resistive stability analysis indicates the performance of NCS discharges with strongly peaked pressure profiles is limited by the resistive interchange mode to low βN≤2.3. This mode is insensitive to the details of the rotational and the magnetic shear profiles. A new class of discharges, which has a broad region of weak or slightly negative magnetic shear (WNS), is described. The WNS discharges have broader pressure profiles and higher β values than the NCS discharges, together with high confinement and high fusion reactivity. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 4751-4753 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recently, Valentini [Phys. Plasmas 3, 1459 (1996)] investigated the influence of collisions on the space charge formation and derived a modified Bohm criterion accounting for collisions in the sheath. It is shown that this derivation is wrong and is based on a misinterpretation of the plasma sheath concept. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 2960-2965 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design of a low-temperature scanning tunneling microscope is described. The microscope can be operated in ultrahigh vacuum in the temperature range between 15 and 300 K. The main features are a scanner which is based on the Besocke "beetle'' design principle combined with a spring suspension of the microscope and complete surrounding of the whole microscope by a 4 K radiation shield. The microscope can be extended to work as a force microscope using the optical lever detection technique for force measurement. It is demonstrated that this comparatively small and reliable setup is well suited to study the adsorption of single atoms and molecules at low temperatures. Moreover, examples of lateral and vertical manipulation of atoms and molecules are shown to demonstrate the performance of the system. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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