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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5452-5452 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Cubic Laves phase alloy YFe2 forms four types of hydrides, YFe2Hx: β1, β2 (hexagonal) of 1.2〈x〈1.6, γ (hexagonal) of 2.8〈x〈3.45, and δ (orthorhombic) of 3.7〈x. The β1 and β2 hydrides are formed in the hydrogen absorption below and above 500 K. The deuterides YFe2Dx have been prepared by deuterium absorption at various temperatures for YFe2 powders of diameters less than 0.3 mm. The formed samples are mixtures of main and extra deuteride phases. The x-ray and magnetization measurements in a magnetic field of 10.6 kOe showed five types of ferromagnetic deuterides with Curie temperatures of about 100 K (δ1), 300 K (δ2), 380 K (γ), 300–380 K (β1), and 540 K (amorphous). The extrapolated values of magnetization at 0 K are 3.5μB/YFe2Dx. The crystal structures are as follows: δ1, hexagonal, a=0.57 nm, c=2.74 nm; δ2, cubic, a=0.79 nm; γ, hexagonal, a=0.56 nm, c=2.63 nm; and β, hexagonal (a=0.53 nm, c=0.87 nm)–(a=0.51 nm, c=0.82 nm). © 1996 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 1040-1042 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Room-temperature vibronic pulsed laser action in trivalent chromium-activated forsterite (Cr3+:Mg2SiO4) is reported for the first time. The free-running laser emission is centered at 1235 nm of the broad 4T2→4A2 fluorescence band, and has a bandwidth of ∼22 nm.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1771-1775 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Resonant tunneling bipolar transistors (RBTs) using InAlAs/InGaAs heterostructures were fabricated. These devices are bipolar transistors which use a resonant tunneling barrier as a minority-carrier injector. The RBT exhibits a collector current peak as a function of the base-emitter voltage at room temperature. The peak-to-valley ratio of the collector current is 3.5, and the peak collector current density is 5.7×104 A/cm2. The common-emitter current gain reaches a value of 24. These InAlAs/InGaAs RBTs characteristics are much better than those of AlGaAs/GaAs RBTs. We measured the microwave characteristics of the InAlAs/InGaAs RBT at room temperature, and obtained a cutoff frequency of 12.4 GHz. An equivalent circuit analysis and device simulation yielded an estimated resonant tunneling barrier response time of 1.4 ps.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3403-3405 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Inelastic scattering of neutrons has been used to study the magnetic excitations in Fe-doped Mn3Si at 7 K. Mn3Si is an incommensurate antiferromagnet with magnetic Bragg points of the form (h,k,l)±(δ,δ,δ) with δ=0.425. Its magnetic excitations are qualitatively similar to those of the γ-Mn alloys, or of the itinerant antiferromagnet, chromium. The addition of 5 at. % of iron causes the value of δ to change to 1/2, so that the material becomes a commensurate antiferromagnet, greatly simplifying the shape of the excitation spectrum. In addition the low Néel temperature (23 K) permits measurements to be extended to energies of several times kTN. Constant energy scans through a magnetic Bragg point are qualitatively consistent with the spin-wave dispersion relation forming a "cone'' around the magnetic Bragg point. Low-energy scans (1 meV≤ΔE≤4 meV) are centered on the Bragg point and flat-topped, while at higher energies (5 meV≤ΔE≤15 meV) the peak is clearly resolved as double. A fit using a damped-harmonic oscillator cross section suggests that the slope of the dispersion relation increases with energy, and that the excitations are highly damped.
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  • 5
    Publication Date: 2015-09-19
    Description: VOLUME 285 (2010) PAGES 5907–5916PAGE 5914:The phase contrast images representing “EXT1+/+ + LIF” and “EXT−/− + HEP” ESCs were switched inadvertently. The corrected Fig. 6D is shown. This correction does not affect the interpretation of the results or the conclusions of this work.jbc;290/38/23023/FU1F1FU1
    Print ISSN: 0021-9258
    Electronic ISSN: 1083-351X
    Topics: Biology , Chemistry and Pharmacology
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  • 6
    Publication Date: 2013-03-16
    Description: Replacement of a specific amino acid residue in a protein with nonnatural analogues is highly challenging because of their cellular toxicity. We demonstrate for the first time the replacement of all arginine (Arg) residues in a protein with canavanine (Can), a toxic Arg analogue. All Arg residues in the 5-base specific (UACAU) mRNA interferase from Bacillus subtilis (MazF-bs(arg)) were replaced with Can by using the single-protein production system in Escherichia coli. The resulting MazF-bs(can) gained a 6-base recognition sequence, UACAUA, for RNA cleavage instead of the 5-base sequence, UACAU, for MazF-bs(arg). Mass spectrometry analysis confirmed that all Arg residues were replaced with Can. The present system offers a novel approach to create new functional proteins by replacing a specific amino acid in a protein with its analogues.
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    Electronic ISSN: 1083-351X
    Topics: Biology , Chemistry and Pharmacology
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  • 7
    Publication Date: 2014-04-05
    Description: The cellular cues that regulate the apoptosis of intestinal stem cells (ISCs) remain incompletely understood, yet may play a role in diseases characterized by ISC loss including necrotizing enterocolitis (NEC). Toll-like receptor-4 (TLR4) was recently found to be expressed on ISCs, where its activation leads to ISC apoptosis through mechanisms that remain incompletely explained. We now hypothesize that TLR4 induces endoplasmic reticulum (ER) stress within ISCs, leading to their apoptosis in NEC pathogenesis, and that high ER stress within the premature intestine predisposes to NEC development. Using transgenic mice and cultured enteroids, we now demonstrate that TLR4 induces ER stress within Lgr5 (leucine-rich repeat-containing G-protein-coupled receptor 5)-positive ISCs, resulting in crypt apoptosis. TLR4 signaling within crypts was required, because crypt ER stress and apoptosis occurred in TLR4ΔIEC-OVER mice expressing TLR4 only within intestinal crypts and epithelium, but not TLR4ΔIEC mice lacking intestinal TLR4. TLR4-mediated ER stress and apoptosis of ISCs required PERK (protein kinase-related PKR-like ER kinase), CHOP (C/EBP homologous protein), and MyD88 (myeloid differentiation primary response gene 88), but not ATF6 (activating transcription factor 6) or XBP1 (X-box-binding protein 1). Human and mouse NEC showed high crypt ER stress and apoptosis, whereas genetic inhibition of PERK or CHOP attenuated ER stress, crypt apoptosis, and NEC severity. Strikingly, using intragastric delivery into fetal mouse intestine, prevention of ER stress reduced TLR4-mediated ISC apoptosis and mucosal disruption. These findings identify a novel link between TLR4-induced ER stress and ISC apoptosis in NEC pathogenesis and suggest that increased ER stress within the premature bowel predisposes to NEC development.
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    Topics: Biology , Chemistry and Pharmacology
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  • 8
    Publication Date: 2013-09-28
    Description: Our previous studies on a β1,6-N-acetylglucosaminyltransferase, GnT-IX (GnT-Vb), a homolog of GnT-V, indicated that the enzyme has a broad GlcNAc transfer activity toward N-linked and O-mannosyl glycan core structures and that its brain-specific gene expression is regulated by epigenetic histone modifications. In this study, we demonstrate the existence of an endogenous inhibitory factor for GnT-IX that functions as a key regulator for GnT-IX enzymatic activity in Neuro2a (N2a) cells. We purified this factor from N2a cells and found that it is identical to ectonucleotide pyrophosphatase/phosphodiesterase 3 (ENPP3), as evidenced by mass spectrometry and by the knockdown and overexpression of ENPP3 in cultured cells. Kinetic analyses revealed that the mechanism responsible for the inhibition of GnT-IX caused by ENPP3 is the ENPP3-mediated hydrolysis of the nucleotide sugar donor substrate, UDP-GlcNAc, with the resulting generation of UMP, a potent and competitive inhibitor of GnT-IX. Indeed, ENPP3 knockdown cells had significantly increased levels of intracellular nucleotide sugars and displayed changes in the total cellular glycosylation profile. In addition to chaperones or other known regulators of glycosyltransferases, the ENPP3-mediated hydrolysis of nucleotide sugars would have widespread and significant impacts on glycosyltransferase activities and would be responsible for altering the total cellular glycosylation profile and modulating cellular functions.
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  • 9
    Publication Date: 2013-11-16
    Description: Heregulin signaling is involved in various tumor proliferations and invasions; thus, receptors of heregulin are targets for the cancer therapy. In this study we examined the suppressing effects of extracellular domains of ErbB2, ErbB3, and ErbB4 (soluble ErbB (sErbB)) on heregulin β signaling in human breast cancer cell line MCF7. It was found that sErbB3 suppresses ligand-induced activation of ErbB receptors, PI3K/Akt and Ras/Erk pathways most effectively; sErbB2 scarcely suppresses ligand-induced signaling, and sErbB4 suppresses receptor activation at ∼10% efficiency of sErbB3. It was revealed that sErbB3 does not decrease the effective ligands but decreases the effective receptors. By using small interfering RNA (siRNA) for ErbB receptors, we determined that sErbB3 suppresses the heregulin β signaling by interfering ErbB3-containing heterodimers including ErbB2/ErbB3. By introducing the mutation of N418Q to sErbB3, the signaling-inhibitory effects were increased by 2–3-fold. Moreover, the sErbB3 N418Q mutant enhanced anticancer effects of lapatinib more effectively than the wild type. We also determined the structures of N-glycan on Asn-418. Results suggested that the N-glycan-deleted mutant of sErbB3 suppresses heregulin signaling via ErbB3-containing heterodimers more effectively than the wild type. Thus, we demonstrated that the sErbB3 N418Q mutant is a potent inhibitor for heregulin β signaling.
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  • 10
    Publication Date: 2013-11-24
    Description: Dendritic cell inhibitory receptor 2 (DCIR2) is a C-type lectin expressed on classical dendritic cells. We recently identified the unique ligand specificity of mouse DCIR2 (mDCIR2) toward biantennary complex-type glycans containing bisecting N-acetylglucosamine (GlcNAc). Here, we report the crystal structures of the mDCIR2 carbohydrate recognition domain in unliganded form as well as in complex with an agalactosylated complex-type N-glycan unit carrying a bisecting GlcNAc residue. Bisecting GlcNAc and the α1-3 branch of the biantennary oligosaccharide asymmetrically interact with canonical and non-canonical mDCIR2 residues. Ligand-protein interactions occur directly through mDCIR2-characteristic amino acid residues as well as via a calcium ion and water molecule. Our structural and biochemical data elucidate for the first time the unique binding mode of mDCIR2 for bisecting GlcNAc-containing glycans, a mode that contrasts sharply with that of other immune C-type lectin receptors such as DC-SIGN.
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