147 research outputs found

    Large phase-transition-induced magnetic anisotropy change in (Co/Pt)2/VO2 heterostructure

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    We report the phase-transition controlled magnetic anisotropy modulation in the (Co/Pt)2/VO2 heterostructure, where VO2 is introduced into the system to applied an interfacial strain by its metal-insulator transition. A large reversible modulation of the perpendicular magnetic anisotropy (PMA) reaching 38 kJ/m3 is observed during this process. The calculated energy density variation of interfacial anisotropy reaches 100 mJ/m2, which shows significant advantage over traditional modulation strategies. Further experimental results including magnetization change versus temperature, strain buffered modulation and pre-strained sample comparison prove that the interfacial coupling between VO2 and PMA layers plays a crucial role in this modulation. This work, demonstrating the great potential of phase-transition material in efficient magnetic anisotropy modulation, would benefit the exploration for low-power consumption devices

    Annealing Effect on Photovoltaic Performance of CdSe Quantum-Dots-Sensitized TiO2 Nanorod Solar Cells

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    Large area rutile TiO₂ nanorod arrays were grown on F:SnO₂ (FTO) conductive glass using a hydrothermal method at low temperature. CdSe quantum dots (QDs) were deposited onto single-crystalline TiO₂ nanorod arrays by a chemical bath deposition (CBD) method to make a photoelectrode. The solar cell was assembled using a CdSe-TiO₂ nanostructure as the photoanode and polysulfide solution as the electrolyte. The annealing effect on optical and photovoltaic properties of CdSe quantum-dotssensitized TiO₂ nanorod solar cells was studied systematically. A significant change of the morphology and a regular red shift of band gap of CdSe nanoparticles were observed after annealing treatment. At the same time, an improved photovoltaic performance was obtained for quantum-dots-sensitized solar cell using the annealed CdSe-TiO₂ nanostructure electrode. The power conversion efficiency improved from 0.59% to 1.45% as a consequence of the annealing effect. This improvement can be explained by considering the changes in the morphology, the crystalline quality, and the optical properties caused by annealing treatment

    Anderson localization for CMV matrices with Verblunsky coefficients defined by the hyperbolic toral automorphism

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    In this paper, we prove the large deviation estimates and Anderson localization for CMV matrices on 2(Z+)\ell^2(\mathbb{Z}_+) with Verblunsky coefficients defined dynamically by the hyperbolic toral automorphism. Part of positivity results on the Lyapunov exponents of Chulaevsky-Spencer and Anderson localization results of Bourgain-Schlag on Schr\"{o}dinger operators with strongly mixing potentials are extended to CMV matrices

    High-Performance Self-Powered Photodetectors Based on ZnO/ZnS Core-Shell Nanorod Arrays

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    In recent years, there is an urgent demand for high-performance ultraviolet photodetectors with high photosensitivity, fast responsivity, and excellent spectral selectivity. In this letter, we report a self-powered photoelectrochemical cell-type UV detector using the ZnO/ZnS core-shell nanorod array as the active photoanode and deionized water as the electrolyte. This photodetector demonstrates an excellent spectral selectivity and a rapid photoresponse time of about 0.04 s. And the maximum responsivity is more than 0.056 (A/W) at 340 nm, which shows an improvement of 180 % compared to detectors based on the bare ZnO nanorods. This improved photoresponsivity can be understood from the step-like band energy alignment of the ZnO/ZnS interface, which will accelerate the separation of photoexcited electron-hole pairs and improve the efficiency of the photodetector. Considering its uncomplicated low-cost fabrication process, and environment-friendly feature, this self-powered device is a promising candidate for UV detector application

    End-of-treatment anti-HBs levels and HBeAg status identify durability of HBsAg loss after PEG-IFN discontinuation

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    BackgroundHepatitis B surface antigen (HBsAg) loss, namely, the functional cure, can be achieved through the pegylated interferon (PEG-IFN)-based therapy. However, it is an unignorable fact that a small proportion of patients who achieved functional cure develop HBsAg reversion (HRV) and the related factors are not well described.MethodsA total of 112 patients who achieved PEG-IFN-induced HBsAg loss were recruited. HBV biomarkers and biochemical parameters were examined dynamically. HBV RNA levels were assessed in the cross-sectional analysis. The primary endpoint was HRV, defined as the reappearance of HBsAg after PEG-IFN discontinuation.ResultsHRV occurred in 17 patients during the follow-up period. Univariable analysis indicated that hepatitis B e antigen (HBeAg) status, different levels of hepatitis B surface antibody (anti-HBs), and hepatitis B core antibody (anti-HBc) at the end of PEG-IFN treatment (EOT) were significantly associated with the incidence of HRV through using the log-rank test. Additionally, time-dependent receiver operating characteristic (ROC) analysis showed that the anti-HBs was superior to anti-HBc in predictive power for the incidence of HRV during the follow-up period. Multivariable Cox proportional hazard analysis found that anti-HBs ≥1.3 log10IU/L (hazard ratio (HR), 0.148; 95% confidence interval (CI), 0.044-0.502) and HBeAg negativity (HR, 0.183; 95% CI, 0.052-0.639) at EOT were independently associated with lower incidence of HRV. Cross-sectional analysis indicated that the HBV RNA levels were significantly correlated with the HBsAg levels in patients with HRV (r=0.86, p=0.003).ConclusionsEOT HBeAg negativity and anti-HBs ≥1.3 log10IU/L identify the low risk of HRV after PEG-IFN discontinuation

    Global, regional, and national burden of headache disorders, 1990–2023: a systematic analysis for the Global Burden of Disease Study 2023

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    Background: The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2023 estimates health loss from migraine, tension-type headache, and medication-overuse headache. This study presents updated results on headache-attributed burden from 1990 to 2023, along with clinical and public health implications. Methods: Data on the prevalence, incidence, or remission of migraine, tension-type headache, and medication-overuse headache were extracted from published population-based studies. We used hierarchical Bayesian meta-regression modelling to estimate global, regional, and country-level prevalence of headache disorders. For the first time in GBD 2023, age-specific and sex-specific estimates of time in symptomatic state were applied by meta-analysing individual participant data from 41 653 individuals from the general populations of 18 countries from all parts of the world. Disability weights were applied to calculate years lived with disability (YLDs). Since medication-overuse headache is a sequela of a mistreated primary headache (due to medication overuse), its burden was reattributed to migraine or tension-type headache, informed by a meta-analysis of three longitudinal studies. Findings: In 2023, 2·9 billion individuals (95% uncertainty interval 2·6–3·1) were affected by headache disorders, with a global age-standardised prevalence of 34·6% (31·6–37·5) and a YLD rate of 541·9 (373·4–739·9) per 100 000 population, with 487·5 (323·0–678·8) per 100 000 population attributed to migraine. The prevalence rates of these headache disorders have remained stable over the past three decades. YLD rates due to headache disorders were more than twice as high in females (739·9 [511·2–1011·5] per 100 000) as in males (346·1 [240·4–481·8] per 100 000). Medication-overuse headache contributed 58·9% of the YLD estimates for tension-type headache in males and 56·1% in females, as well as 22·6% of the YLD estimates for migraines in males and 14·1% in females. Interpretation: Headache disorders, in particular migraine, continue to be a major global health challenge, emphasising the need for effective management and prevention strategies. Much headache-attributed burden could be averted or eliminated by avoiding overuse of medication (including over-the-counter medication), underscoring the importance of public education

    Annealing Effect on SB2S3-TiO2 Nanostructures for Solar Cell Applications

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    Nanostructures composited of vertical rutile TiO₂ nanorod arrays and Sb₂S₃ nanoparticles were prepared on an F:SnO₂ conductive glass by hydrothermal method and successive ionic layer adsorption and reaction method at low temperature. Sb₂S₃-sensitized TiO₂ nanorod solar cells were assembled using the SB₂S₃-TiO₂ nanostructure as the photoanode and a polysulfide solution as an electrolyte. Annealing effects on the optical and photovoltaic properties of SB₂S₃-TiO₂ nanostructure were studied systematically. As the annealing temperatures increased, a regular red shift of the bandgap of Sb₂S₃ nanoparticles was observed, where the bandgap decreased from 2.25 to 1.73 eV. At the same time, the photovoltaic conversion efficiency for the nanostructured solar cells increased from 0.46% up to 1.47% as a consequence of the annealing effect. This improvement can be explained by considering the changes in the morphology, the crystalline quality, and the optical properties caused by the annealing treatment

    Reversible Control of the Magnetization of Fe₃O₄ via Lithium Ions

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    In this report, a reversible control of Fe₃O₄ saturated magnetization by Li ions is demonstrated. A miniature Li ion battery (LIB) was assembled using a Fe₃O₄ nanoparticle layer as the active cathode. A stable magnetism modulation is realized by a nondestructive electrochemical process in which the lithium insertion results in a valence change and partial redistribution of Fe cations in the crystal structure. The relation between the discharge voltage and the chemical phases were studied by ex situ X-ray diffraction and magnetic measurement. In a suitable discharge potential range, a reversible control of Fe₃O₄ saturated magnetization was obtained without structural damage to the magnetic electrode. The experimental results indicate by further optimizing the LIB\u27s performance, a large reversible change in magnetization could be realized at room temperature, suggesting the potential for future practical applications
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