GLORIA

GEOMAR Library Ocean Research Information Access

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
Materialart
Sprache
Erscheinungszeitraum
  • 1
    Online-Ressource
    Online-Ressource
    International Union of Crystallography (IUCr) ; 2018
    In:  Journal of Synchrotron Radiation Vol. 25, No. 5 ( 2018-09-01), p. 1395-1399
    In: Journal of Synchrotron Radiation, International Union of Crystallography (IUCr), Vol. 25, No. 5 ( 2018-09-01), p. 1395-1399
    Kurzfassung: This work reports an unconventional defect engineering approach using synchrotron-radiation-based X-rays on ceria nanocrystal catalysts of particle sizes 4.4–10.6 nm. The generation of a large number of oxygen-vacancy defects (OVDs), and therefore an effective reduction of cations, has been found in CeO 2 catalytic materials bombarded by high-intensity synchrotron X-ray beams of beam size 1.5 mm × 0.5 mm, photon energies of 5.5–7.8 keV and photon fluxes up to 1.53 × 10 12 photons s −1 . The experimentally observed cation reduction was theoretically explained by a first-principles formation-energy calculation for oxygen vacancy defects. The results clearly indicate that OVD formation is mainly a result of X-ray-excited core holes that give rise to valence holes through electron down conversion in the material. Thermal annealing and subvalent Y-doping were also employed to modulate the efficiency of oxygen escape, providing extra control on the X-ray-induced OVD generating process. Both the core-hole-dominated bond breaking and oxygen escape mechanisms play pivotal roles for efficient OVD formation. This X-ray irradiation approach, as an alternative defect engineering method, can be applied to a wide variety of nanostructured materials for physical-property modification.
    Materialart: Online-Ressource
    ISSN: 1600-5775
    Sprache: Unbekannt
    Verlag: International Union of Crystallography (IUCr)
    Publikationsdatum: 2018
    ZDB Id: 2021413-3
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    In: Physical Review B, American Physical Society (APS), Vol. 81, No. 4 ( 2010-1-11)
    Materialart: Online-Ressource
    ISSN: 1098-0121 , 1550-235X
    RVK:
    Sprache: Englisch
    Verlag: American Physical Society (APS)
    Publikationsdatum: 2010
    ZDB Id: 1473011-X
    ZDB Id: 2844160-6
    ZDB Id: 209770-9
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 9, No. 1 ( 2019-05-29)
    Kurzfassung: Ultraviolet (UV) light irradiation on CeO 2 nanocrystals catalysts has been observed to largely increase the material’s catalytic activity and reactive surface area. As revealed by x-ray absorption near edge structure (XANES) analysis, the concentration of subvalent Ce 3+ ions in the irradiated ceria samples progressively increases with the UV-light exposure time. The increase of Ce 3+ concentration as a result of UV irradiation was also confirmed by the UV-vis diffuse reflectance and photoluminescence spectra that indicate substantially increased concentration of oxygen vacancy defects in irradiated samples. First-principle formation-energy calculation for oxygen vacancy defects revealed a valence-hole-dominated mechanism for the irradiation-induced reduction of CeO 2 consistent with the experimental results. Based on a Mars-van Krevelen mechanism for ceria catalyzed oxidation processes, as the Ce 3+ concentration is increased by UV-light irradiation, an increased number of reactive oxygen atoms will be captured from gas-phase O 2 by the surface Ce 3+ ions, and therefore leads to the observed catalytic activity enhancement. The unique annealing-free defect engineering method using UV-light irradiation provides an ultraconvenient approach for activity improvement in nanocrystal ceria for a wide variety of catalytic applications.
    Materialart: Online-Ressource
    ISSN: 2045-2322
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2019
    ZDB Id: 2615211-3
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2016-02, No. 31 ( 2016-09-01), p. 2059-2059
    Kurzfassung: With continuous increase in transistor count and clock frequency, the power density of current Si integrated circuits has reached a level that calls for a revolutionary change in transistor technology. High hole mobility Ge and high electron mobility InGaAs have been considered to be the most promising channel materials for p-channel and n-channel MOSFETs, respectively. Selective-area growth (SAG) on nano-trenches has been quite popular in integrating III-V materials with Si substrates. Since there exists a high lattice mismatch between III-V materials and Si, obtaining defect-free epilayer is still a great challenge. In this work, we demonstrate selective area growth of InGaAs on Ge trenches aiming at integrating n-channel InGaAs FinFETs and p-channel Ge FinFETs side by side on a Si substrate for CMOS applications. The Ge templates, which were grown on Si by chemical vapor deposition, were prepared by etching through an oxide mask using a dilute H 2 O 2 solution to create Ge linear trench structures with embedded {111} facets at the bottom of the trenches for facilitating the regrowth of III-V materials. The III-V materials were selectively grown on the patterned Ge templates by metal-organic vapor phase epitaxy. An InGaP buffer layer, which has a wide bandgap and is beneficial for electrical isolation between the channel and substrate, was grown onto the Ge trenches. Undoped InGaAs was grown on InGaP as the n-channel material. High resolution transmission microscopy investigations show that very few dislocations are present near the Ge/InGaP interface in the trenches. It is found that In content of InGaP increases from 50 % to about 70 % with growth as evidenced by energy-dispersive x-ray spectroscopy (EDX). Interestingly, composition grading is also observed on the subsequently grown InGaAs. It begins from an In 0.21 Ga 0.79 As layer, which has good lattice match to the In 0.7 Ga 0.3 P layer beneath, then changes to the nominal In 0.71 Ga 0.29 As layer near the top of the fin. The strain in InGaAs is partially released through the generation of dislocations near the InGaAs/InGaP interface, leading to a nearly defect-free region at the top of the fin. A growth mechanism is proposed to account for the correlation between strain accommodation, composition grading, and defects generation.
    Materialart: Online-Ressource
    ISSN: 2151-2043
    Sprache: Unbekannt
    Verlag: The Electrochemical Society
    Publikationsdatum: 2016
    ZDB Id: 2438749-6
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    In: Chemistry of Materials, American Chemical Society (ACS), Vol. 29, No. 13 ( 2017-07-11), p. 5537-5549
    Materialart: Online-Ressource
    ISSN: 0897-4756 , 1520-5002
    Sprache: Englisch
    Verlag: American Chemical Society (ACS)
    Publikationsdatum: 2017
    ZDB Id: 1500399-1
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Online-Ressource
    Online-Ressource
    Optica Publishing Group ; 2021
    In:  Optics Letters Vol. 46, No. 2 ( 2021-01-15), p. 416-
    In: Optics Letters, Optica Publishing Group, Vol. 46, No. 2 ( 2021-01-15), p. 416-
    Kurzfassung: An integrated optical chip that minimizes the size of the energy-tuning single-resonance-mode x-ray monochromator system into a 3 c m × 5 c m silicon wafer is proposed. A Fabry–Perot x-ray resonator and two back-reflecting Si mirrors are employed on the wafer as the optical components, where Si(12 4 0) back reflection is used for both Fabry–Perot resonance and re-diffraction of the x-ray beams from the resonator in the incident direction. We can achieve an energy bandwidth of 3.4 meV in single-mode x rays and tune the energy by temperature variation. Such Si chips can be readily employed at the synchrotron beamlines and conventional x-ray laboratories for high-resolution investigations.
    Materialart: Online-Ressource
    ISSN: 0146-9592 , 1539-4794
    Sprache: Englisch
    Verlag: Optica Publishing Group
    Publikationsdatum: 2021
    ZDB Id: 243290-0
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    In: Geriatrics & Gerontology International, Wiley, Vol. 19, No. 1 ( 2019-01), p. 56-60
    Kurzfassung: This study aimed to evaluate the association between tamoxifen use and hip fractures in older women with breast cancer in Taiwan. Methods We carried out a retrospective nationwide case–control study using the database of the Taiwan National Health Insurance Program. A total of 762 female patients with breast cancer aged ≥65 years newly diagnosed with hip fractures from 2000 to 2011 were identified for inclusion in the study. Additionally, 7620 female patients with breast cancer aged ≥65 years without hip fractures were randomly selected as controls. Patients were defined as having used tamoxifen if they had an existing prescription for tamoxifen before the index date. Patients were defined as having never used tamoxifen if they had never been given a prescription for tamoxifen before the index date. We used an unconditional logistic regression model to calculate the odds ratio and 95% confidence interval for the association between tamoxifen use and risk of hip fractures. Results After adjustment for confounding variables, compared with patients who did not use tamoxifen, the adjusted odds ratio of hip fracture was 2.29 for those who had used tamoxifen (95% confidence interval 1.92, 2.72). Furthermore, adjusted odds ratios were 2.74 (95% confidence interval 2.19, 3.42) among patients with a cumulative duration of tamoxifen use of 〉 3 years. Conclusion Tamoxifen use is associated with increased risk of hip fractures among older women with breast cancer in Taiwan. Geriatr Gerontol Int 2019; 19: 56–60 .
    Materialart: Online-Ressource
    ISSN: 1444-1586 , 1447-0594
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2019
    ZDB Id: 2078308-5
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    In: Family Practice, Oxford University Press (OUP), Vol. 35, No. 2 ( 2018-03-27), p. 166-171
    Materialart: Online-Ressource
    ISSN: 0263-2136 , 1460-2229
    Sprache: Englisch
    Verlag: Oxford University Press (OUP)
    Publikationsdatum: 2018
    ZDB Id: 1484852-1
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    In: Medicine, Ovid Technologies (Wolters Kluwer Health), Vol. 98, No. 40 ( 2019-10), p. e17238-
    Kurzfassung: Arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis due to its higher patency and lower infection rate. However, its suboptimal maturation rate is a major weakness. Although substantial risk factors for AVF maturation failure have been disclosed, modifiable risk factors remain unknown. During the AVF maturation process, an elevated luminal pressure is required for outward remodeling; however, excessively high luminal pressure may also be detrimental to AVF maturation, which remains to be defined. We hypothesized that higher AVF luminal pressure is harmful to its maturation, and investigate its potential as a modifiable factor to improve AVF maturation. Methods and analysis: This prospective study includes patients undergoing surgical creation for a native AVF. The exclusion criteria were as follows: age 〈 20 years, inability to sign an informed consent, and failure to create a native AVF due to technical difficulties. Demographic and laboratory profiles will be collected before AVF surgery. Vascular sonography will be performed within 1 week of AVF creation to measure the diameters, flow rates, and flow volumes of AVF and its branched veins. The pressure gradient within AVF will be estimated from the blood flow rates using the modified Bernoulli equation. The primary outcome is spontaneous AVF maturation defined as provision of sufficient blood flow for hemodialysis within 2 months of its creation without any interventional procedures. The secondary outcome is assisted AVF maturation, which is defined as AVF maturation within 2 months from its creation aided by any interventional procedure before the successful use of AVF. Discussion: While contemporary theory for AVF maturation failure focuses on disturbed wall shear stress, complicate assumptions and measurement preclude its clinical applicability. AVF luminal pressure, which may be manipulated pharmaceutically and surgically, may be a target to improve the outcome of AVF maturation. Trial registration: This study has been registered at the protocol registration and results system. The Protocol ID: NCT04017806.
    Materialart: Online-Ressource
    ISSN: 0025-7974 , 1536-5964
    Sprache: Englisch
    Verlag: Ovid Technologies (Wolters Kluwer Health)
    Publikationsdatum: 2019
    ZDB Id: 2049818-4
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 10, No. 1 ( 2020-07-22)
    Kurzfassung: While the patency of vascular access is essential for hemodialysis patients, optimal pharmaceutical treatment to maintain arteriovenous fistula (AVF) patency remains lacking. As cardiovascular diseases are highly prevalent in patients with end-stage renal disease, various cardiovascular medications have also been used to maintain AVF patency. However, previous studies revealed inconsistent therapeutic effects and a comprehensive evaluation of this issue is needed. The present retrospective, longitudinal cohort study included patients receiving successful AVF creation. The evaluated cardiovascular medications included antiplatelet agents, antihypertensive agents, nitrates and nitrites, statins, dipyridamole, and pentoxifylline. The outcome was AVF primary patency. All laboratory data and medication profiles were recorded at baseline and followed at 3-month interval, until the end of the 2-year study period. Cox proportional regression model with time-dependent covariates was used to evaluate the risk for AVF patency loss. A total of 349 patients were included in the present study, in which 57% were men and the mean age was 65 ± 14 years. Among the included patients, 40% used antiplatelet agents, 27% used dipyridamole and 36% used statins at baseline. Of all the evaluated cardiovascular medications, only dipyridamole showed significant association with a higher risk for loss of AVF patency. To evaluate the effect of combination of antiplatelet agents and dipyridamole, the patients were classified into four groups, I: combine use of antiplatelet agents and dipyridamole, II: antiplatelet only, III: dipyridamole only; IV: none of both were used. Of the four groups, group IV exhibited highest AVF patency (52.4%), which was followed by group III (42.7%), group II (40%), and group I (28.6%), respectively. Compared with group IV, only group I showed a significantly higher risk for AVF patency loss. None of the cardiovascular medications evaluated in the present study showed a beneficial effect on AVF patency. Furthermore, dipyridamole showed an association with a higher risk of AVF patency loss. We do not suggest a beneficial effect of dipyridamole on maintaining AVF patency, particularly in combination with antiplatelet agents.
    Materialart: Online-Ressource
    ISSN: 2045-2322
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2020
    ZDB Id: 2615211-3
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...