Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Self-organization of comblike copolymers with end-functionalized side chains: A cellular-automaton-based simulation (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 11069-11079 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Using the cellular-automaton-based simulation technique, we study the processes of self-organization in the systems of comblike copolymers with strongly attracting groups located at the ends of side chains. It is found that at a certain critical association energy, dependent both on polymer volume fraction and on the chemical composition of the copolymers, a micellar phase is nucleated. For the combs with large linear grafting density, a weak extension of the macromolecules is observed as attraction between end groups is increased. We find that the micelle formation observed in the sufficiently dense systems is mainly a result of intermolecular association. From the analysis of the static structure factors and snapshot pictures, it is concluded that the system is spatially inhomogeneous on the intermediate length scales related to the average intermicellar distances. Strong attraction stabilizes the aggregates (multiplets) that serve as junction points of a temporary network (micellar gel). We observe the formation of a specific space-filling weblike network in which strongly attracting side-chain ends group into multiplets which are wrapped by neutral polymer sections connecting these multiplets. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481747
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Accurate calibration technique for a resonant-mass gravitational wave detector (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 4282-4285 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The methodology for accurately calibrating the Niobe resonant-mass gravitational wave detector is presented. The transducer is based on a low noise resonant microwave cavity transducer that converts the displacement of the resonating mass to microwave energy. The calibration technique consists of a one off measurement of the microwave frequency versus resonant-mass displacement characteristic. To measure this accurately, known static forces were applied to the resonant mass and the change in the transducer microwave frequency was recorded. With the aid of finite element analysis and accurate measurements of the resonant-mass characteristics, the deflection due to the known force was calculated. The calculated deflections were verified coarsely with measurements from a calibrated linear variable differential transformer. Typically, the detector operates with a 1 mK noise temperature. A best noise temperature of 890 μK between 1300 and 2000 Universal Time Coordinate (UTC) for day 60 in 1997 is reported. The transducer has been upgraded with a new microwave amplifier, which has a measured electronic noise floor 40 dB lower than the previous amplifier, which is only 10 dB above the quantum limit. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1319982
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Characterization of nanostructured metal films by picosecond acoustics and interferometry (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 4852-4858 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Picosecond interferometry is used to study the acoustics waves created by heating Pt films with a subpicosecond laser pulse. Both the period of the initial oscillations in the metal film and the amplitude of the sound wave in the substrate are measured quantitatively. The platinum films are roughened by irradiation with energetic ions. The amplitude of the sound wave is doubled at those irradiation levels where the platinum coverage has been reduced by about one-half. A theory for the amplitude of the launched acoustic wave predicts that the acoustic amplitude is proportional to the mean square film thickness. Thus changes in the morphology of a partially perforated metal film can be observed using a simple, nondestructive optical technique. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1406543
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Dewetting and nanopattern formation of thin Pt films on SiO2 induced by ion beam irradiation (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 7777-7783 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dewetting and nanopattern formation of 3–10 nm Pt thin films upon ion irradiation is studied using scanning electron microscopy (SEM). Lateral feature size and the fraction of exposed surface area are extracted from SEM images and analyzed as functions of ion dose. The dewetting phenomenon has little temperature dependence for 3 nm Pt films irradiated by 800 keV Kr+ at temperatures ranging from 80 to 823 K. At 893 K, the films dewet without irradiation, and no pattern formation is observed even after irradiation. The thickness of the Pt films, in the range 3–10 nm, influences the pattern formation, with the lateral feature size increasing approximately linearly with film thickness. The effect of different ion species and energies on the dewetting process is also investigated using 800 keV Kr+ and Ar+ irradiation and 19.5 keV He+, Ar+, Kr+, and Xe+ irradiation. The lateral feature size and exposed surface fraction scale with energy deposition density (J/cm2) for all conditions except 19.5 keV Xe+ irradiation. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1372623
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Thermal conductivity of amorphous carbon thin films (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 6317-6320 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thermal conductivities Λ of amorphous carbon thin films are measured in the temperatures range 80–400 K using the 3ω method. Sample films range from soft a-C:H prepared by remote-plasma deposition (Λ=0.20 W m−1 K−1 at room temperature) to amorphous diamond with a large fraction of sp3 bonded carbon deposited from a filtered-arc source (Λ=2.2 W m−1 K−1). Effective-medium theory provides a phenomenological description of the variation of conductivity with mass density. The thermal conductivities are in good agreement with the minimum thermal conductivity calculated from the measured atomic density and longitudinal speed of sound. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1314301
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    The charge of glass and silica surfaces (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 6716-6721 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a method of calculating the electric charge density of glass and silica surfaces in contact with aqueous electrolytes for two cases of practical relevance that are not amenable to standard techniques: surfaces of low specific area at low ionic strength and surfaces interacting strongly with a second anionic surface. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1404988
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Annealing thin colloidal crystals with optical gradient forces (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 7570-7573 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We describe methods for annealing colloidal crystals using scanned optical tweezers. Tweezer-induced excitations drive a well-localized region of the colloidal lattice out of thermal equilibrium with its supporting fluid. Subsequent plastic and elastic relaxation of defects yields large defect-free domains. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1359741
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Nanoscale pattern formation in Pt thin films due to ion-beam-induced dewetting (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 3215-3217 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Atomic force microscopy is used to characterize the evolution of film morphology produced by heavy-ion bombardment. Pt films, 3 and 5 nm thick, are deposited on SiO2 substrates and subsequently bombarded by 800 keV Kr+. Ion doses of 〉2×1014 initiate pattern formation and the dewetting of Pt films from the substrate. The film morphology becomes increasingly disconnected with increasing dose; at the highest doses, (∼2×1016 cm−2), isolated nanoparticles are formed with a uniform spacing. The results are explained by the nucleation of bare substrate patches and subsequent coarsening of the morphology by the molten zones created by individual Kr+ impacts. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126633
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Relationships between superoxide levels and delayed calcium deregulation in cultured cerebellar granule cells exposed continuously to glutamate (2004)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 90 (2004), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The relationship is investigated between superoxide levels in single cultured rat cerebellar granule neurons exposed continuously to glutamate in low KCl medium and the deregulation of cytoplasmic Ca2+. Cells that maintain a regulated cytoplasmic-free Ca2+ and mitochondrial polarization in the presence of glutamate show no increase in superoxide levels until the onset of cytoplasmic Ca2+ deregulation. Oxidative stress of mitochondrial origin is readily detectable, as the inhibitors rotenone and antimycin A markedly increase superoxide levels with no effect on cytoplasmic-free Ca2+. The potent cell-permeant superoxide dismutase/catalase mimetic manganese tetrakis (N-ethylpyridinium-2yl) porphyrin, MnTE-PyP, abolishes the deregulation-related increase in superoxide but has no effect on deregulation itself. A combination of catalase with the free radical scavenger 4-hydroxy-TEMPO also fails to reduce deregulation. Following the loss of Ca2+ homeostasis nuclei undergo condensation; this morphological change is not inhibited by MnTE-PyP and cannot account for the increased ethidium fluorescence. Phospholipase A2 inhibitors decrease the deregulation-related increase in superoxide without protecting against deregulation. In conclusion, our study indicates that deregulation is not caused by NMDA receptor-mediated oxidative stress as NMDA receptor activation does not increase superoxide levels until the onset of deregulation. Furthermore, the majority of superoxide is produced in the cytoplasm rather than in mitochondria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.2004.02516.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Presenilin-1 and intracellular calcium stores regulate neuronal glutamate uptake (2004)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 88 (2004), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Glutamate uptake by high affinity glutamate transporters is essential for preventing excitotoxicity and maintaining normal synaptic function. We have discovered a novel role for presenilin-1 (PS1) as a regulator of glutamate transport. PS1-deficient neurons showed a decrease in glutamate uptake of approximately 50% compared to wild-type neurons. Gamma-secretase inhibitor treatment mimicked the effects of PS1 deficiency on glutamate uptake. PS1 loss-of-function, accomplished by PS1 deficiency or γ-secretase inhibitor treatment, caused a corresponding decrease in cell surface expression of the neuronal glutamate transporter, EAAC1. PS1 deficiency is known to reduce intracellular calcium stores. To explore the possibility that PS1 influences glutamate uptake via regulation of intracellular calcium stores, we examined the effects of treating neurons with caffeine, thapsigargin, and SKF-96365. These compounds depleted intracellular calcium stores by distinct means. Nonetheless, each treatment mimicked PS1 loss-of-function by impairing glutamate uptake and reducing EAAC1 expression at the cell surface. Blockade of voltage-gated calcium channels, activation and inhibition of protein kinase C (PKC), and protein kinase A (PKA) all had no effect on glutamate uptake in neurons. Taken together, these findings indicate that PS1 and intracellular calcium stores may play a significant role in regulating glutamate uptake and therefore may be important in limiting glutamate toxicity in the brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2003.02279.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...