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  • 1
    Electronic Resource
    Electronic Resource
    Adrenal Medullary Transplants Increase Spinal Cord Cerebrospinal Fluid Catecholamine Levels and Reduce Pain Sensitivity (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 56 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Previous work in this laboratory has shown that adrenal medullary transplants into the spinal cord subarachnoid space can reduce pain sensitivity. This analgesia most likely results from the release of neuroactive substances, particularly catecholamines and opioid peptides, from the transplanted cells into the CSF of the spinal cord, since it can be attenuated or blocked by α-adrenergic or opiate antagonists. The purpose of the present study was to more directly measure the release of catecholamines from adrenal medullary transplants in the spinal cord CSF using a spinal superfusion technique. CSF samples from rats with 6-month-old transplants were assayed for catecholamines using HPLC with electrochemical detection. Results indicated that norepinephrine levels were increased threefold, and epinephrine levels nearly 100-fold, in animals with adrenal medullary transplants compared with control transplanted animals. There was no apparent increase in dopamine levels. Furthermore, the increased levels of total catecholamines were correlated with decreased pain sensitivity. Results of this study indicate that adrenal medullary transplants can survive for long periods in the rat spinal CSF and continue to release high levels of catecholamines. Together, the release of catecholamines and opioid peptides from adrenal medullary transplants may provide the ideal combination for the reduction of pain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb08195.x
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  • 2
    Electronic Resource
    Electronic Resource
    Induction of Nitric Oxide Synthase in Rat C6 Glioma Cells (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 62 (1994), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: We have examined the induction of nitric oxide syhthase (NOS) activity in the rat astrocyte-derived C6 glioma cell line. In contrast to the previous results with primary astrocyte cultures, incubation of C6 cells with bacterial endotoxin lipopolysaccharide (LPS; 1 μg/ml for 24 h) did not stimulate NO2 production. However, addition of either tumor necrosis factor-a (TNF-α) or interferon-γ (IFN-γ), cytokines that by themselves had no effect on NOS activity, imparted LPS responsiveness onto these cells in a dose-dependent manner (EC50 values of 39 ng/ml of TNF-α and 9.4 U/ml of IFN-γ), and the effect of TNF-α could be further potentiated (twofold) by the presence of interleukin-1β. The simultaneous presence of TNF-α and IFN-γ yielded a greater response than either cytokine alone; however, the respective EC50 values were not affected. A cytoplasmic extract from induced C6 cells catalyzed the Ca2+-independent conversion of l-arginine to l- citrulline, with an apparent Km of 51.2 nM, and this activity could be blocked by l-arginine analogues in the potency order amino 〉 methyl 〉 nitroarginine. Immunoblot analysis revealed an apparent molecular mass of 125 kDa for the NOS protein induced in C6 cells. These results indicate that the combination of LPS plus cytokines can induce NOS activity in C6 glioma cells with properties similar to those of the enzyme expressed in primary astrocyte cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1994.62010315.x
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  • 3
    Electronic Resource
    Electronic Resource
    Reactions of N and NO on Pt(335) (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 9569-9576 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: As part of a study of species important in automotive exhaust chemistry, the reactivity of atomic N and NO on Pt(335) at low temperature has been studied. The atomic N was produced by dissociating adsorbed NO with a 76 eV electron beam. Cross sections for electron-stimulated desorption and dissociation are estimated for NO on terrace and step sites. Terrace NO is at least five times more likely to desorb than to dissociate. Step NO has a lower desorption cross section than terrace NO, but probably a higher dissociation cross section. Temperature-programmed desorption was used to monitor desorption, dissociation, and the formation of N2 and N2O from adsorbed N and NO. Five distinct desorption states of N2 formed by NO dissociation are identified. The dominant N2 peak (435 K) comes from electron-dissociated step NO; its desorption temperature is higher than the N2 peaks from electron-dissociated terrace NO. Coadsorbed N and NO react to form N2O even below 100 K, with an activation barrier of ∼6 kcal/mol. Only terrace NO participates in this reaction; step NO does not react to form N2O. This site dependence resembles that for CO oxidation on Pt(112) and Pt(335) and can be rationalized with simple steric considerations. All of the forms of atomic N participate in N2O formation, but that formed by the dissociation of step NO exhibits the lowest reaction temperature. Hence, the same N atoms that only recombine to form N2 at 435 K, react with NO to form N2O at 100 K. We found no evidence for an NO reaction with N atoms to form N2 and adsorbed O, or for NO formation from the recombination of adsorbed N and adsorbed O2. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475254
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  • 4
    Electronic Resource
    Electronic Resource
    CO on Pt(335): Electric field screening on a stepped surface (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 2711-2718 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We compare CO's response to electric fields at edge and terrace sites on the stepped Pt(335) surface. The comparison is made at zero frequency and at the frequency of the C–O stretch vibration. Atop-bonded CO is observed with reflection–absorption ir spectroscopy (RAIRS), electroreflectance vibrational spectroscopy (EVS), and high-resolution electron energy loss spectroscopy (HREELS). Coadsorbed H or O is used to control the CO adsorption site. With both RAIRS and HREELS the measured vibrational cross-section of atop CO at the step edge is 2.0±0.2 times greater than for CO on the terrace. The vibrational Stark effect—the change of CO's vibrational frequency with externally applied electrostatic field—is also a factor 2.0±0.2 larger for atop CO at the step edge than it is for atop CO on the terrace. Because the vibrational cross section varies as the square of the field while the Stark effect is linear, a model in which CO responds to the screened local field at a single point cannot simultaneously explain the observed site dependence of both the vibrational Stark effect and the vibrational cross section. The most plausible explanation is that CO's response to electric fields is nonlocal. A simple model is presented that can account for our data. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470505
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  • 5
    Electronic Resource
    Electronic Resource
    Coadsorption of hydrogen and CO on Pt(335): Structure and vibrational Stark effect (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 4277-4287 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have studied CO and H coadsorbed on the stepped Pt(335) surface in vacuum to learn about their interaction at steps and to compare with previous electrochemical studies. Both electroreflectance and conventional reflectance absorption vibrational spectra were obtained of atop bonded CO. Its stretch vibrational frequency ν, Stark tuning rate (dν/dE), and integrated absorbance S were all studied as functions of CO and H coverage. With CO only on step edges, S for atop CO decreases to zero with increasing H coverage. The CO affected by H is in a mixed phase and is bridge bonded. Atop CO's (dν/dE) decreases with increasing CO coverage but is unaffected by coadsorbed H. In the low CO coverage limit (dν/dE)=88±9 cm−1/(V/A(ring)), in agreement with theory and with previous measurement. The standard model of dipole–dipole screening is unable to explain the CO coverage dependence of both (dν/dE) and S. The vibrational polarizability of CO increases with coverage. We also compare our results with spectroelectrochemical data from CO on Pt(335) in aqueous electrolyte. Our measured (dν/dE) is too small to explain the variation of CO's ν with electrode potential φ in the electrochemical experiments if (dE/dφ) in the double-layer is taken from conventional models. The effect of coadsorbed H is also different; in vacuum H has no effect on CO's (dν/dE) but in electrolyte, at low CO coverage, (dν/dφ) drops to zero at the potential where H adsorption begins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467478
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  • 6
    Electronic Resource
    Electronic Resource
    Preparation and Synchrotron X-ray Specular Reflectivity Study of Langmuir-Blodgett Films of the Phthalocyanine [(C6H13)3SiO(SiPcO)2H] (1995)
    s.l. : American Chemical Society
    Langmuir 11 (1995), S. 4549-4553 
    Details
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/la00011a059
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  • 7
    Electronic Resource
    Electronic Resource
    Gas-Sensing Mechanism of Phthalocyanine Langmuir-Blodgett Films (1994)
    s.l. : American Chemical Society
    Langmuir 10 (1994), S. 790-796 
    Details
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/la00015a032
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  • 8
    Electronic Resource
    Electronic Resource
    Thermally stable spin valve films with synthetic antiferromagnet pinned by NiMn for recording heads beyond 20 Gbit/in.2 (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5720-5722 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The thermal stability of spin valve films with synthetic antiferromagnet (SAF) pinned by antiferromagnetic IrMn, NiO, and NiMn layers were studied. The SAF layer enhances the thermal stability in general; however, the blocking temperature (and the blocking temperature distribution) of the antiferromagnet is still important for the magnetic rigidity of the pinned layer. Once the temperature reaches the blocking temperature the SAF layer can go into either the spin flip or flop state, depending upon the magnetic moment ratio of the reference layer and pinned layers. The GMR linear head response can be distorted for nonlinearity. The NiMn pinned SAF structure shows magnetic and thermal stability which makes it practical for the real products. A high GMR of 11% can be obtained in both bottom and top NiMn SAF spin valves by advanced processes. Recording heads were built using such stacks which demonstrated recording areal density of 20 Gbit/in.2 and beyond. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372500
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  • 9
    Electronic Resource
    Electronic Resource
    A study on pinned layer magnetization processes in different antiferromagnetic coupling systems of spin-valves (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5729-5731 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper we report on magnetization reversal processes of pinned layers in different ferromagnetic and anti-ferromagnetic bilayer and spin-valve structures by observing hysteresis, switching field distribution (SFD), and time-dependent effects. The fact that time-dependent coercivity Hc tendency is more pronounced in ordered AF materials than that of disordered AF materials implies a spin reversal of some AF grains with locally low pinning field and low blocking temperature. We propose a simple qualitative model to explain our results in terms of a distribution of the pinning reversal field and temperature in AF layer, which may be due to a grain size distribution in the AF layer and an incomplete and inhomogeneous phase transformation in some ordered AF materials. High resolution electron microscopy (HREM) results reveal that lattice spacing does change from place to place in AF region of some ordered AF materials. The evidence indicates an incomplete and inhomogeneous phase transformation in the ordered AF systems, supporting the results of the magnetization reversal process study. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372503
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  • 10
    Electronic Resource
    Electronic Resource
    Nondestructive determination of beryllium outdiffusion in AlGaAs/GaAs heterojunction bipolar transistor structures by low-temperature photoluminescence (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 4267-4272 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this work, low-temperature photoluminescence (PL) is used for the investigation of beryllium (Be) dopant outdiffusion in AlGaAs/GaAs single-heterojunction bipolar transistors (HBTs). Near the typical emission peak at ∼1.92 eV which is due to the band-to-band transition from AlGaAs emitter, an additional emission peak is found in the PL spectrum. This peak is found to be caused by the Be-related transition from AlGaAs emitter due to the Be outdiffusion from the GaAs base to the AlGaAs emitter. The concentration of Be outdiffused into the emitter can be estimated from the energy separation between these two emission peaks in AlGaAs range based on the band gap narrowing effect. The measured dc current gain and the emitter-base turn-on voltage of the HBTs fabricated on different wafers with different growth conditions were found to correlate well with the PL results. Our results demonstrate that low temperature PL technique is an efficient method in identifying Be outdiffusion in HBTs and is useful in HBT growth and device structure optimization. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371356
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