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  • 1
    Electronic Resource
    Electronic Resource
    Internal friction and Young's modulus of SrBi2Ta2O9 ceramics (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 1453-1457 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The internal friction (IF) and the Young's modulus of SrBi2Ta2O9 (SBT) ceramics were measured by using the reed vibration method in the temperature range from 100 to 600 K with kilo-hertz frequencies. A high IF peak associated with a modulus defect appeared around 500 K, which was assumed to be due to the migration of oxygen vacancies with the activation energy U of about 0.95 eV. The mechanism of the IF peak was discussed in detail. At 570 K, an IF peak due to the viscous motion of domain walls near the Curie temperature was found. Below room temperature, a low IF peak with a modulus defect was found with peak temperature of 200–250 K, which varied for tens of degrees in different samples. This peak was due to the depinning process of 90° domain walls from oxygen vacancies. These results can be helpful in explaining the excellent fatigue resistance property of SBT thin films at room temperature. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372034
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of heavy metal remediation using mineral apatite (1997)
    Springer
    Water, air & soil pollution 98 (1997), S. 57-78 
    Details
    ISSN: 1573-2932
    Keywords: acid mine drainage ; desorption ; phosphate rock ; pollution control ; remediation technology ; soil and groundwater contamination ; sorption ; TLCP ; toxic metals ; waste management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The current study investigated the sorption and desorption of dissolved lead (Pb), cadmium (Cd) and zinc (Zn) from aqueous solutions and a contaminated soil by North Carolina mineral apatite. Aqueous solutions of Pb, Cd, and Zn were reacted with the apatite, followed by desorption experiments under a wide variety of pH conditions ranging from 3 to 12, including the extraction fluids used in the Toxicity Characteristic Leaching Procedure (TCLP) of the United States Environmental Protection Agency (US EPA). The sorption results showed that the apatite was very effective in retaining Pb and was moderately effective in attenuating Cd and Zn at pH 4–5. Approximately 100% of the Pb applied was removed from solutions, representing a capacity of 151 mg of Pb/g of apatite, while 49% of Cd and 29% of Zn added were attenuated, with removal capacities of 73 and 41 mg g−1, respectively. The desorption experiments showed that the sorbed Pb stayed intact where only 14–23% and 7–14% of the sorbed Cd and Zn, respectively, were mobilized by the TCLP solutions. The apatite was also effective in removing dissolved Pb, Cd, and Zn leached from the contaminated soil using pH 3–12 solutions by 62.3–99.9, 20–97.9, and 28.6–98.7%, respectively. In particular, the apatite was able to reduce the metal concentrations in the TCLP-extracted soil leachates to below US EPA maximum allowable levels, suggesting that apatite could be used as a cost-effective option to remediating metal-contaminated soils, wastes, and/or water. The sorption mechanisms are variable in the reactions between the apatite and dissolved Pb, Cd, and Zn. The Pb removals primarily resulted from the dissolution of the apatite followed by the precipitation of hydroxyl fluoropyromorphite. Minor otavite precipitation was observed in the interaction of the apatite with aqueous Cd, but other sorption mechanisms, such as surface complexation, ion exchange, and the formation of amorphous solids, are primarily responsible for the removal of Zn and Cd.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02128650
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  • 3
    Electronic Resource
    Electronic Resource
    EVALUATION OF HEAVY METAL REMEDIATION USING MINERAL APATITE (1997)
    Springer
    Water, air & soil pollution 98 (1997), S. 57-78 
    Details
    ISSN: 1573-2932
    Keywords: acid mine drainage ; desorption ; phosphate rock ; pollution control ; remediation technology ; soil and groundwatercontamination ; sorption ; TLCP ; toxic metals ; waste management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The current study investigated the sorption and desorption of dissolved lead (Pb), cadmium (Cd) and zinc (Zn) from aqueous solutions and a contaminated soil by North Carolina mineral apatite. Aqueous solutions of Pb, Cd, and Zn were reacted with the apatite, followed by desorption experiments under a wide variety of pH conditions ranging from 3 to 12, including the extraction fluids used in the Toxicity Characteristic Leaching Procedure (TCLP) of the United States Environmental Protection Agency (US EPA). The sorption results showed that the apatite was very effective in retaining Pb and was moderately effective in attenuating Cd and Zn at pH 4–5. Approximately 100% of the Pb applied was removed from solutions, representing a capacity of 151 mg of Pb/g of apatite, while 49% of Cd and 29% of Zn added were attenuated, with removal capacities of 73 and 41 mg g-1, respectively. The desorption experiments showed that the sorbed Pb stayed intact where only 14–23% and 7–14% of the sorbed Cd and Zn, respectively, were mobilized by the TCLP solutions. The apatite was also effective in removing dissolved Pb, Cd, and Zn leached from the contaminated soil using pH 3–12 solutions by 62.3–99.9, 20–97.9, and 28.6–98.7%, respectively. In particular, the apatite was able to reduce the metal concentrations in the TCLP-extracted soil leachates to below US EPA maximum allowable levels, suggesting that apatite could be used as a cost-effective option to remediating metal-contaminated soils, wastes, and/or water. The sorption mechanisms are variable in the reactions between the apatite and dissolved Pb, Cd, and Zn. The Pb removals primarily resulted from the dissolution of the apatite followed by the precipitation of hydroxyl fluoropyromorphite. Minor otavite precipitation was observed in the interaction of the apatite with aqueous Cd, but other sorption mechanisms, such as surface complexation, ion exchange, and the formation of amorphous solids, are primarily responsible for the removal of Zn and Cd.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026425931811
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  • 4
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    Distribution of postsynaptic density (PSD)-95 and Ca2+/calmodulin-dependent protein kinase II at the PSD (2009)
    Society for Neuroscience
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © Society for Neuroscience, 2003. This article is posted here by permission of Society for Neuroscience for personal use, not for redistribution. The definitive version was published in Journal of Neuroscience 23 (2003): 11270-11278.
    Description: Postsynaptic densities (PSDs) contain proteins that regulate synaptic transmission. We determined the positions of calcium/calmodulin-dependent protein kinase II (CaMKII) and PSD-95 within the three-dimensional structure of isolated PSDs using immunogold labeling, rotary shadowing, and electron microscopic tomography. The results show that all PSDs contain a central mesh immediately underlying the postsynaptic membrane. Label for PSD-95 is found on both the cytoplasmic and cleft sides of this mesh, averaging 12 nm from the cleft side. All PSDs label for PSD-95. The properties of CaMKII labeling are quite different. Label is virtually absent on the cleft sides of PSDs, but can be heavy on the cytoplasmic side at a mean distance of 25 nm from the cleft. In tomograms, CaMKII holoenzymes can be visualized directly, appearing as labeled, tower-like structures reflecting the 20 nm diameter of the holoenzyme. These towers protrude from the cytoplasmic side of the central mesh. There appears to be a local organization of CaMKII, as judged by fact that the nearest-neighbor distances are nearly invariant over a wide range of labeling density for CaMKII. The average density of CaMKII holoenzymes is highly variable, ranging from zero to values approaching a tightly packed state. This variability is significantly higher than that for PSD-95 and is consistent with an information storage role for CaMKII.
    Description: This work was supported by National Institute of Neurological Disorders and Stroke Grants RO1 NS-27337 and RO1 NS-35083 (J.L.).
    Keywords: Postsynaptic density ; CaMKII ; PSD ; PSD-95 ; Electron microscopy ; Tomography
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 5
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    Palmitoylation regulates glutamate receptor distributions in postsynaptic densities through control of PSD95 conformation and orientation (2016)
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of National Academy of Sciences of the United States of America for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 113 (2016): E8482-E8491, doi: 10.1073/pnas.1612963113.
    Description: PSD95 and SAP97 are homologous scaffold proteins with different N-terminal domains, possessing either a palmitoylation site (PSD95) or an L27 domain (SAP97). Here, we measured PSD95 and SAP97 conformation in vitro and in postsynaptic densities (PSDs) using FRET and electron microscopy, and examined how conformation regulated interactions with AMPA-type and NMDAtype glutamate receptors (AMPARs/NMDARs). Palmitoylation of PSD95 changed its conformation from a compact to an extended configuration. PSD95 associated with AMPARs (via TARP subunits) or NMDARs (via GluN2B subunits) only in its palmitoylated and extended conformation. In contrast, SAP97 in its extended conformation associates with NMDARs but not with AMPARs. Within PSDs, PSD95 and SAP97 were largely in the extended conformation, but had different orientations. PSD95 oriented perpendicular to the PSD membrane, with its palmitoylated, N-terminal domain at the membrane. SAP97 oriented parallel to the PSD membrane, likely as a dimer through interactions of its N-terminal, L27 domain. Changing PSD95 palmitoylation in PSDs altered PSD95 and AMPAR levels but did not affect NMDAR levels. These results indicate that in PSDs, PSD95 palmitoylation, conformation and its interactions are dynamic when associated with AMPARs, and more stable when associated with NMDARs. Altogether, our results are consistent with differential regulation of PSD95 palmitoylation in PSDs resulting from the clustering of palmitoylating and depalmitoylating enzymes into AMPAR nanodomains segregated away from NMDAR nanodomains.
    Description: This work was supported by the U.S. National Institutes of Health under grant numbers NS043782, MH081251 and DA019695 (WNG) and NINDS intramural funds (TSR). This project was also supported by the National Center for Research Resources and the National Center for Advancing Translational Sciences of the National Institutes of Health through Grant Number UL1 RR024999 (O.J.).
    Description: 2017-06-12
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 6
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    Temperature behavior of electron-acceptor transitions and oxygen vacancy recombinations in ZnO thin films (2010)
    American Institute of Physics
    Details
    Publication Date: 2010-01-15
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics
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  • 7
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    Palmitoylation regulates glutamate receptor distributions in postsynaptic densities through control of PSD95 conformation and orientation (2016)
    National Academy of Sciences
    Details
    Publication Date: 2016-12-12
    Description: Postsynaptic density protein 95 (PSD95) and synapse-associated protein 97 (SAP97) are homologous scaffold proteins with different N-terminal domains, possessing either a palmitoylation site (PSD95) or an L27 domain (SAP97). Here, we measured PSD95 and SAP97 conformation in vitro and in postsynaptic densities (PSDs) using FRET and EM, and examined how conformation regulated interactions with AMPA-type and NMDA-type glutamate receptors (AMPARs/NMDARs). Palmitoylation of PSD95 changed its conformation from a compact to an extended configuration. PSD95 associated with AMPARs (via transmembrane AMPAR regulatory protein subunits) or NMDARs [via glutamate ionotropic receptor NMDA-type subunit 2B (GluN2B) subunits] only in its palmitoylated and extended conformation. In contrast, in its extended conformation, SAP97 associates with NMDARs, but not with AMPARs. Within PSDs, PSD95 and SAP97 were largely in the extended conformation, but had different orientations. PSD95 oriented perpendicular to the PSD membrane, with its palmitoylated, N-terminal domain at the membrane. SAP97 oriented parallel to the PSD membrane, likely as a dimer through interactions of its N-terminal L27 domain. Changing PSD95 palmitoylation in PSDs altered PSD95 and AMPAR levels but did not affect NMDAR levels. These results indicate that in PSDs, PSD95 palmitoylation, conformation, and its interactions are dynamic when associated with AMPARs and more stable when associated with NMDARs. Altogether, our results are consistent with differential regulation of PSD95 palmitoylation in PSDs resulting from the clustering of palmitoylating and depalmitoylating enzymes into AMPAR nanodomains segregated away from NMDAR nanodomains.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 8
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    Interfacial coupling-induced distinct magnetic structure in La1/2Sr1/2CoO2.5+δ/La2/3Sr1/3MnO3/ La1/2Sr1/2CoO2.5+δ heterostructure (2019)
    American Institute of Physics
    Details
    Publication Date: 2019-03-01
    Electronic ISSN: 2158-3226
    Topics: Physics
    Published by American Institute of Physics
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  • 9
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    PSD-95 family MAGUKs are essential for anchoring AMPA and NMDA receptor complexes at the postsynaptic density (2015)
    National Academy of Sciences
    Details
    Publication Date: 2015-11-24
    Description: The postsynaptic density (PSD)-95 family of membrane-associated guanylate kinases (MAGUKs) are major scaffolding proteins at the PSD in glutamatergic excitatory synapses, where they maintain and modulate synaptic strength. How MAGUKs underlie synaptic strength at the molecular level is still not well understood. Here, we explore the structural and functional roles of MAGUKs at hippocampal excitatory synapses by simultaneous knocking down PSD-95, PSD-93, and synapse-associated protein (SAP)102 and combining electrophysiology and transmission electron microscopic (TEM) tomography imaging to analyze the resulting changes. Acute MAGUK knockdown greatly reduces synaptic transmission mediated by α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPARs) and N-methyl-d-aspartate receptors (NMDARs). This knockdown leads to a significant rise in the number of silent synapses, diminishes the size of PSDs without changes in pre- or postsynaptic membrane, and depletes the number of membrane-associated PSD-95–like vertical filaments and transmembrane structures, identified as AMPARs and NMDARs by EM tomography. The differential distribution of these receptor-like structures and dependence of their abundance on PSD size matches that of AMPARs and NMDARs in the hippocampal synapses. The loss of these structures following MAGUK knockdown tracks the reduction in postsynaptic AMPAR and NMDAR transmission, confirming the structural identities of these two types of receptors. These results demonstrate that MAGUKs are required for anchoring both types of glutamate receptors at the PSD and are consistent with a structural model where MAGUKs, corresponding to membrane-associated vertical filaments, are the essential structural proteins that anchor and organize both types of glutamate receptors and govern the overall molecular organization of the PSD.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 10
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    Two-dimensional electron gas at manganite buffered LaAlO3/SrTiO3 (001) interface by spin coating chemical methods (2018)
    American Institute of Physics
    Details
    Publication Date: 2018-08-13
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Published by American Institute of Physics
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