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BACKGROUND: Magic-based programs have been utilised to enhance well-being across various health aspects. However, there is a lack of studies on whether performing magic tricks can provide mental health benefits for older adults living in the community. Therefore, this study aims to investigate the effects of a magic-based intervention program on self-esteem, depressive symptoms, and quality of life (QOL), and to examine the relationship between these factors in older adults. METHODS: Thirty-eight participants, aged 60-90 years, were randomly assigned to either a magic intervention group or a control group. The magic intervention program, tailored for older adults, was conducted for 90 min, twice weekly, over 6 weeks. The Rosenberg Self-Esteem Scale (RSE), the 15-item Geriatric Depression Scale (GDS-15), and the World Health Organization Quality of Life-BREF scores were measured and analyzed in both groups before and after the intervention. RESULTS: The magic-based intervention significantly increased self-esteem and reduced depressive symptoms in older adults, with large effect sizes. However, no significant impact on QOL was observed. Additionally, no significant correlation was found between the improvement in self-esteem and the reduction in depressive levels. Despite this, a moderate but significant negative correlation was detected between the post-intervention scores of RSE and GDS-15 in the magic intervention group. CONCLUSIONS: The study demonstrated that the magic intervention program was beneficial in promoting mental health in community-dwelling older adults. Implementing magic programs in communities appears to be an effective approach to enhance self-esteem and alleviate depressive symptoms in the older population.
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Depresión , Vida Independiente , Humanos , Anciano , Depresión/psicología , Calidad de Vida/psicología , Salud Mental , AutoimagenRESUMEN
Because of the expected long spin-transport length of organic materials, the magnetic metal/organic interface is crucial to the application of organic spintronics. In this study, [Fe/C60]3 multilayers were fabricated for the investigation of C60-mediated magnetic interlayer coupling. [Fe/C60]3 thin films were characterized using the magneto-optical Kerr effect, transmission electron microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS). The thin films revealed in-plane magnetic anisotropy, and the magnetic coercivity (H c ) drastically decreased from 6-8 mT to 0.5 mT with the increase of C60 thickness from 0.1 nm to 5 nm. The insertion of the C60 layer considerably reduced H c because a thickness greater than 1 nm of the C60 layer is sufficient for blocking magnetic exchange coupling between Fe layers. In addition, post-annealing increased H c because of Fe inter-diffusion, which promotes magnetic exchange coupling and further Fe-C bonding, as confirmed by a comparative study of XPS C-spectra. The thermally triggered inter-diffusion between Fe and C60 layers turned the multilayers into a mixed composite film and thus caused magnetic variation. Annealing time and temperature can be used as control parameters for the tuning of magnetism in Fe-C60 composites.
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Graphene (Gr) has been demonstrated to protect metallic thin films against oxidation. Based on this idea, we propose a new method to fabricate microstructured magnetic domains using patterned single-layer Gr. In the first experiment, single-layer Gr was transferred onto a CoPd alloy film pregrown on a SiO2/Si(001) substrate. Subsequently, the single-layer Gr was patterned through electron beam lithography followed by oxygen plasma etching to expose selective micron-sized areas of CoPd. The exposed areas of CoPd were more easily oxidized compared to the areas protected by Gr, which is found to result in significant magnetic contrast between the protected and surface-oxidized areas of CoPd. In the second experiment, a lithographically-patterned Gr layer was placed between the Fe and CoPd layers to block interlayer diffusion area-selectively during sample annealing. Magnetic contrast is observed to be established between the Pd/Fe/Gr/CoPd and Pd/Fe/CoPd areas, leading to a magnetic structure that matches the pattern of the lithographed Gr. These observations demonstrate that Gr patterning is a simple and powerful method for magnetic patterning, which can be applied in the fabrication of future data-storage and spintronic devices.
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Enterovirus 71 (EV71) is responsible for the outbreaks of hand-foot-and-mouth disease in the Asia-Pacific region. To produce the virus-like particle (VLP) vaccine, we previously constructed recombinant baculoviruses to co-express EV71 P1 polypeptide and 3CD protease using the Bac-to-Bac(®) vector system. The recombinant baculoviruses resulted in P1 cleavage by 3CD and subsequent VLP assembly in infected insect cells, but caused either low VLP yield or excessive VLP degradation. To tackle the problems, here we explored various expression cassette designs and flashBAC GOLD™ vector system which was deficient in v-cath and chiA genes. We found that the recombinant baculovirus constructed using the flashBAC GOLD™ system was insufficient to improve the EV71 VLP yield. Nonetheless, BacF-P1-C3CD, a recombinant baculovirus constructed using the flashBAC GOLD(TM) system to express P1 under the polh promoter and 3CD under the CMV promoter, dramatically improved the VLP yield while alleviating the VLP degradation. Infection of High Five(TM) cells with BacF-P1-C3CD enhanced the total and extracellular VLP yield to ≈268 and ≈171 mg/L, respectively, which enabled the release of abundant VLP into the supernatant and simplified the downstream purification. Intramuscular immunization of mice with 5 µg purified VLP induced cross-protective humoral responses and conferred protection against lethal virus challenge. Given the significantly improved extracellular VLP yield (≈171 mg/L) and the potent immunogenicity conferred by 5 µg VLP, one liter High Five(TM) culture produced ≈12,000 doses of purified vaccine, thus rendering the EV71 VLP vaccine economically viable and able to compete with inactivated virus vaccines.
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Baculoviridae , Enterovirus Humano A/genética , Vacunas de Partículas Similares a Virus/metabolismo , Proteínas Virales/metabolismo , Virosomas/metabolismo , Animales , Anticuerpos Antivirales/sangre , Asia , Modelos Animales de Enfermedad , Infecciones por Enterovirus/inmunología , Infecciones por Enterovirus/prevención & control , Vectores Genéticos , Inyecciones Intramusculares , Insectos , Ratones , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Análisis de Supervivencia , Vacunas de Partículas Similares a Virus/administración & dosificación , Vacunas de Partículas Similares a Virus/genética , Vacunas de Partículas Similares a Virus/inmunología , Proteínas Virales/genética , Virosomas/administración & dosificación , Virosomas/genética , Virosomas/inmunologíaRESUMEN
Hydrogenation-induced modification of magnetic properties has been widely studied. A Mg spacer layer with high hydrogen storage stability was clamped in a Pd/Co/Mg/Fe multilayer structure to enhance its hydrogen storage stability and explore the structure's magneto-transport properties. After 1 bar hydrogen exposure, the formation of a stable MgH2 phase was demonstrated in an ambient environment at room temperature through X-ray diffraction. Lower magnetic coupling and enhanced magnetoresistance, compared to those of the as-grown sample, were observed using the longitudinal magneto-optical Kerr effect and a four-probe measurement. In this study, the hydrogenation stability of ferromagnetic multilayers was improved, and the concept of a hydrogenation-based spintronic device was developed.
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BACKGROUND: Effective therapy for COVID-19 remains limited. Hydroxychloroquine (HCQ) has been considered, but safety and efficacy concerns remain. Chitosan exhibits antiviral and immunomodulatory effects, yet how the combination of HCQ and chitosan performs in treating COVID-19 is unknown. METHODS: Male Syrian hamsters were inoculated intranasally with standardized stocks of the SARS-CoV-2 virus. Hamsters were allocated to saline (PBS), chitosan oligosaccharide (COS), HCQ, or COS + HCQ groups and received corresponding drugs. On days 1, 7, and 14 post-infection, two animals from each group were euthanized for sample collection. Viral loads were measured in lung homogenates. Biochemistry markers, cytokines, and immunoglobulins were analyzed from hamster sera. HCQ concentrations were compared between the blood, bronchoalveolar lavage, and lung tissues. All groups underwent histopathology exams of the lungs. Additional hamsters were treated with the same drugs to assess for toxicities to the heart and liver. RESULTS: Among all groups, viral loads in the COS + HCQ group were the lowest by day 8. The COS + HCQ group produced the highest interleukin (IL)-6 levels on day 4, and the highest IL-10, IgA and IgG levels on day 8. HCQ concentrations were higher in the COS + HCQ group's lungs than the HCQ group, despite having received half the dose of HCQ. Histopathology demonstrated earlier inflammation resolution and swifter viral clearance in the COS + HCQ group. There was no evidence of cardiac or hepatic injury in hamsters that received HCQ. CONCLUSION: In hamsters infected with the SARS-CoV-2 virus, the combination of intranasal COS and HCQ was associated with increased HCQ absorption in the lungs, more effective immune responses, without increasing the risk of hepatic or cardiac injuries.
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A class of 1-(4-(arylethylenylcarbonyl)phenyl)-4-carboxy-2-pyrrolidinones were designed and synthesized via Michael addition, cyclization, aldol condensation, and deprotonation to inhibit the human transmembrane protease serine 2 (TMPRSS2) and Furin, which are involved in priming the SARS-CoV-2 Spike for virus entry. The most potent inhibitor 2f (81) was found to efficiently inhibit the replication of various SARS-CoV-2 delta and omicron variants in VeroE6 and Calu-3 cells, with EC50 range of 0.001-0.026 µM by pre-incubation with the virus to avoid the virus entry. The more potent antiviral activities than the proteases inhibitory activities led to discovery that the synthesized compounds also inhibited Spike's receptor binding domain (RBD):angiotensin converting enzyme 2 (ACE2) interaction as a main target, and their antiviral activities were enhanced by inhibiting TMPRSS2 and/or Furin. To further confirm the blocking effect of 2f (81) on virus entry, SARS-CoV-2 Spike pseudovirus was used in the entry assay and the results showed that the compound inhibited the pseudovirus entry in a ACE2-dependent pathway, via mainly inhibiting RBD:ACE2 interaction and TMPRSS2 activity in Calu-3 cells. Finally, in the in vivo animal model of SARS-CoV-2 infection, the oral administration of 25 mg/kg 2f (81) in hamsters resulted in reduced bodyweight loss and 5-fold lower viral RNA levels in nasal turbinate three days post-infection. Our findings demonstrated the potential of the lead compound for further preclinical investigation as a potential treatment for SARS-CoV-2.
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COVID-19 , SARS-CoV-2 , Animales , Humanos , Furina/farmacología , Enzima Convertidora de Angiotensina 2/química , Pirrolidinonas/farmacología , Antivirales/farmacología , Glicoproteína de la Espiga del Coronavirus/metabolismo , Internalización del VirusRESUMEN
[This corrects the article DOI: 10.3389/fnagi.2022.854984.].
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Objectives: Cognitive training is one of the management options for elderly individuals who suffer from mild cognitive impairment (MCI) and an effective way to improve executive function. This study aimed to evaluate the effectiveness of a magic intervention program as a method of cognitive training in improving cognitive function and neurocognitive performance in this group. Methods: Twenty-four participants aged 60-80 years with MCI were recruited and randomly assigned to a magic intervention group or a control group. The magic intervention group received a 6-week magic intervention program. The primary endpoints were the scores for the cognitive assessment tests [e.g., Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA)] for general cognitive function. The secondary endpoints were the behavioral [e.g., accuracy and reaction times] and the electroencephalographic [e.g., event-related potential (ERP) P3 amplitudes] performance during the Flanker task to assess attention and inhibitory control. All variables were measured before and after the magic intervention. Results: The results showed that the 6-week magic intervention significantly improved the MoCA scores in the cognitive assessment tests although no significant pre-post intervention difference was observed in the MMSE scores. In terms of neurocognitive performance, the magic intervention had significantly positive effects on the accuracy, reaction times, and P3 amplitudes when performing the Flanker task. Conclusion: The results of the present study showed that the 6-week magic intervention had beneficial effects on the cognitive and electrophysiological performance in the elderly subjects with MCI. For such a group, lifestyle intervention programs that encourage participation such as the magic practice and performance may be a viable suggestion to prevent the progression of MCI to Alzheimer's disease.
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Array-patterned CoPd-based heterostructures are created through e-beam lithography and plasma pretreatment that induces oxidation with depth gradient in the CoPd alloy films, breaking the central symmetry of the structure. Effects on the magnetic properties of the follow-up hydrogenation of the thin film are observed via magneto-optic Kerr effect microscopy. The system exhibits a strong vertical and lateral antiferromagnetic coupling in the perpendicular component between the areas with and without plasma pretreatment, and asymmetric domain-wall propagation in the plasma-pretreated areas during magnetization reversal. These phenomena exhibit evident magnetic chirality and can be interpreted with the Ruderman-Kittel-Kasuya-Yosida coupling and the Dzyaloshinskii-Moriya interaction (DMI). The sample processing demonstrated in this study allows easy incorporation of lithography techniques that can define areas with or without DMI to create intricate magnetic patterns on the sample, which provides an avenue toward more sophisticated control of canted spin textures in future spintronic devices.
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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus that causes coronavirus disease 2019 (COVID-19). However, the long-term health consequences of COVID-19 are not fully understood. We aimed to determine the long-term lung pathology and blood chemistry changes in Syrian hamsters infected with SARS-CoV-2. Syrian hamsters (Mesocricetus auratus) were inoculated with 105 PFU of SARS-CoV-2, and changes post-infection (pi) were observed for 20 days. On days 5 and 20 pi, the lungs were harvested and processed for pathology and viral load count. Multiple blood samples were collected every 3 to 5 days to observe dynamic changes in blood chemistry. Infected hamsters showed consistent weight loss until day 7 pi At day 5 pi, histopathology of the lungs showed moderate to severe inflammation and the virus could be detected. These results indicate that SARS-CoV-2 has an acute onset and recovery course in the hamster infection model. During the acute onset, blood triglyceride levels increased significantly at day 3 pi During the recovery course, uric acid and low-density lipoprotein levels increased significantly, but the total protein and albumin levels decreased. Together, our study suggests that SARS-CoV-2 infection in hamsters not only causes lung damage but also causes long-term changes in blood biochemistry during the recovery process. IMPORTANCE COVID-19 is now considered a multiorgan disease with a wide range of manifestations. There are increasing reports of persistent and long-term effects after acute COVID-19, but the long-term health consequences of COVID-19 are not fully understood. This study reported for the first time the use of blood samples collected continuously in a SARS-CoV-2-infected hamster model, which provides more information about the dynamic changes in blood biochemistry during the acute and recovery phases of SARS-CoV-2 infection. Our study suggests that SARS-CoV-2 infection in hamsters not only causes lung damage but also causes long-term changes in blood biochemistry during the recovery process. The study may be used by several researchers and clinicians, especially those who are studying potential treatments for patients with post-acute COVID-19 syndrome.
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COVID-19/complicaciones , SARS-CoV-2/fisiología , Animales , COVID-19/sangre , COVID-19/inmunología , COVID-19/patología , COVID-19/virología , Cricetinae , Modelos Animales de Enfermedad , Humanos , Lipoproteínas LDL/sangre , Pulmón/inmunología , Pulmón/patología , Pulmón/virología , Masculino , Mesocricetus , Ácido Úrico/sangre , Síndrome Post Agudo de COVID-19RESUMEN
Background: Drug repurposing is a fast and effective way to develop drugs for an emerging disease such as COVID-19. The main challenges of effective drug repurposing are the discoveries of the right therapeutic targets and the right drugs for combating the disease. Methods: Here, we present a systematic repurposing approach, combining Homopharma and hierarchal systems biology networks (HiSBiN), to predict 327 therapeutic targets and 21,233 drug-target interactions of 1,592 FDA drugs for COVID-19. Among these multi-target drugs, eight candidates (along with pimozide and valsartan) were tested and methotrexate was identified to affect 14 therapeutic targets suppressing SARS-CoV-2 entry, viral replication, and COVID-19 pathologies. Through the use of in vitro (EC50 = 0.4 µM) and in vivo models, we show that methotrexate is able to inhibit COVID-19 via multiple mechanisms. Results: Our in vitro studies illustrate that methotrexate can suppress SARS-CoV-2 entry and replication by targeting furin and DHFR of the host, respectively. Additionally, methotrexate inhibits all four SARS-CoV-2 variants of concern. In a Syrian hamster model for COVID-19, methotrexate reduced virus replication, inflammation in the infected lungs. By analysis of transcriptomic analysis of collected samples from hamster lung, we uncovered that neutrophil infiltration and the pathways of innate immune response, adaptive immune response and thrombosis are modulated in the treated animals. Conclusions: We demonstrate that this systematic repurposing approach is potentially useful to identify pharmaceutical targets, multi-target drugs and regulated pathways for a complex disease. Our findings indicate that methotrexate is established as a promising drug against SARS-CoV-2 variants and can be used to treat lung damage and inflammation in COVID-19, warranting future evaluation in clinical trials.
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COVID-19 , SARS-CoV-2 , Animales , Cricetinae , Metotrexato/farmacología , Metotrexato/uso terapéutico , Antivirales/farmacología , Antivirales/uso terapéutico , Inflamación/tratamiento farmacológico , Biología ComputacionalRESUMEN
We measured the magnetic hysteresis and coercivity of individual Co and Co0.8Fe0.2 bilayer nano-sized island structures formed on Cu (111) substrate using spin-polarized scanning tunneling microscopy. From the hysteresis taken on various sizes of islands, we found that the alloyed islands are ferromagnetic with out-of-plane magnetic anisotropy, same as the pure islands. Coercivity of the alloy islands, which is dependent on their size, was significantly reduced to ≈40% of that of the pure islands. Based on the Stoner-Wohlfarth model, we evaluated the amount of magnetic anisotropic energy and anisotropy constant for both pure and alloy islands. Since tunneling spectra taken on the alloy islands show upward shifts of the valence electronic states as compared to the pure ones, fewer electrons populated in the valence band of the alloy islands are presumably responsible for the reduction in the magnetic anisotropic energy.
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All-optical switching of magnetic materials is a potential method for realizing high-efficiency and high-speed data writing in spintronics devices. The current method, which utilizes two circular helicities of light to manipulate magnetic domains, is based on femtosecond pulsed lasers. In this study, we demonstrate a new all-optical switching method using a continuous-wave Laguerre-Gaussian beam (twisted light), which allows photons to carry orbital angular momentum with discrete levels, lâ, to modify the magnetic anisotropy of an interlayer exchange coupling system. The easy axis of the heterojunction Pt(5 nm)/Co(1.2 nm)/Ru(1.4 nm)/Co(0.4 nm)/Pt(5 nm) on a SiO2/Si substrate dramatically changed after illuminating it with a laser beam carrying a sufficient quantum number of orbital angular momentum. Based on a simple numerical calculation, we deduced that the interaction between the dynamical phase rotation of the electric field and the metal surface could generate an in-plane circular current loop that consequently induces a perpendicular stray field to change the magnetic anisotropy. This finding paves the way for developments in the field of magnetic-based spintronics using light with orbital angular momentum.
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The manipulated nucleation of Fe on hexagonal close-packed (hcp) and face centered cubic (fcc) areas of an Au(111) herringbone surface was demonstrated with the combined growth methods of Xe buffer layer, seed effect and low temperature deposition. Besides the herringbone kinks, bi-layer stacking at fcc gaps was observed. This preference resulted in various nucleation patterns, such as zigzag stripes and doublet islands, by properly choosing the growth condition. The idea of nucleation control through combined growth methods can be applied in other nanopatterned templates for the fabrication of self-assembled nanostructures.
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Bovine enteric bacterial pathogens are a major cause of health decline in agricultural cattle populations. The identification of host-derived microbiota with probiotic characteristics is key for the development of treatments utilizing pathogen displacement and recolonization by commensal flora. In this study, intestinal microbiota in fecal samples from four Holstein dairy cows were analyzed using 16S ribosomal RNA gene next-generation sequencing, leading to the identification of three Lactobacillus isolates (Lactobacillus gasseri, Lactobacillus reuteri, and Lactobacillus salivarius). By taking advantage of the preferential growth in acidified culture media, bacterial characteristics examination, and restriction fragment length polymorphism analysis of 16S rRNA genes, the three lactic acid bacteria (LAB) strains were successfully isolated. The three LAB isolates possess the prerequisite growth tolerances for probiotic functionality, as well as exhibit effective antimicrobial potency against enteric bacterial pathogens of cattle, including Escherichia coli O157:H7, Mycobacterium avium subspecies paratuberculosis, and Salmonella species (Salmonella enteritidis, Salmonella typhimurium, and Salmonella Dublin). Moreover, the LAB isolates showed significant adhesion to cattle intestine, implying greater survivability potential due to their species specificity when administered in the same host species. The LAB isolates were sensitive to most antibiotics with notable resistances of L. gasseri to streptomycin and L. salivarius to kanamycin. Genes attributed to specific antibiotic resistances demonstrated a low risk of lateral transfer in a conjugation study. Our in vitro results demonstrate the promising probiotic characteristics of these newly identified Lactobacillus strains and their considerable potential to serve as probiotics feed supplements for cows.
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Novel low-pathogenic avian influenza (LPAI) H5N2 viruses hit poultry farms in Taiwan in 2003, and evolved into highly pathogenic avian influenza (HPAI) viruses in 2010. These viruses are reassortant viruses containing HA and NA genes from American-lineage H5N2 and six internal genes from local H6N1 viruses. According to a serological survey, the Taiwan H5N2 viruses can cause asymptomatic infections in poultry workers. Therefore, a development of influenza H5N2 vaccines is desirable for pandemic preparation. In this study, we employed reverse genetics to generate a vaccine virus having HA and NA genes from A/Chicken/CY/A2628/2012 (E7, LPAI) and six internal genes from a Vero cell-adapted high-growth H5N1 vaccine virus (Vero-15). The reassortant H5N2 vaccine virus, E7-V15, presented high-growth efficiency in Vero cells (512 HAU, 107.6 TCID50/mL), and passed all tests for qualification of candidate vaccine viruses. In ferret immunization, two doses of inactivated whole virus antigens (3 µg of HA protein) adjuvanted with alum could induce robust antibody response (HI titre 113.14). In conclusion, we have established reverse genetics to generate a qualified reassortant H5N2 vaccine virus for further development.
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Subtipo H5N2 del Virus de la Influenza A/inmunología , Vacunas contra la Influenza/inmunología , Vacunas contra la Influenza/aislamiento & purificación , Gripe Humana/prevención & control , Virus Reordenados/inmunología , Animales , Anticuerpos Antivirales/sangre , Chlorocebus aethiops , Hurones , Glicoproteínas Hemaglutininas del Virus de la Influenza/genética , Glicoproteínas Hemaglutininas del Virus de la Influenza/inmunología , Humanos , Subtipo H5N2 del Virus de la Influenza A/genética , Subtipo H5N2 del Virus de la Influenza A/crecimiento & desarrollo , Subtipo H5N2 del Virus de la Influenza A/aislamiento & purificación , Vacunas contra la Influenza/administración & dosificación , Vacunas contra la Influenza/genética , Neuraminidasa/genética , Neuraminidasa/inmunología , Virus Reordenados/genética , Virus Reordenados/crecimiento & desarrollo , Virus Reordenados/aislamiento & purificación , Genética Inversa , Taiwán , Resultado del Tratamiento , Vacunas de Productos Inactivados/administración & dosificación , Vacunas de Productos Inactivados/inmunología , Células Vero , Proteínas Virales/genética , Proteínas Virales/inmunologíaRESUMEN
In this study, the microscopic origin of the hydrogen effect on magnetic materials was explored through the characterization of time-dependent magnetic domain evolution. We prepared 25-nm Co30Pd70 alloy films with canted magnetic moment on SiO2/Si(001) substrates. From macroscopic Kerr hysteresis loops, considerable hydrogen-induced reduction of magnetic coercivity by a factor of 1/5 in a longitudinal direction and enhancement of magnetic remanence to saturation ratio from 60% to 100% were observed. The magnetic reversal behavior of the Co30Pd70 alloy films gradually transformed from nucleation- to domain-wall-motion dominance when H2 pressure was increased from a vacuum of 1 × 10-5 mbar to 0.8 bar. Domain size also increased considerably with H2 pressure. When H2 pressure was above 0.4 bar, the domain wall (DW) motion was clear to observe and the DW velocity was approximately 10-6-10-5 m/s. Greater hydrogen content in the Co30Pd70 alloy films promoted DW motion that was closer to the behavior of a thermally activated model. The hydrogen effects on magnetism were observed to be reversible and could have valuable future application in spintronic devices for hydrogen sensing.
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[Pd/Fe]2 multilayers were deposited on a flat MgO(001) to study the effect of hydrogen on magnetic interlayer coupling. Complex magnetic hysteresis behavior, including single, double, and triple loops, were measured as a function of the azimuthal angle in a longitudinal and transverse direction. With a combination of a 2-fold magnetic anisotropy energy (MAE) in the bottom-Fe and a 4-fold MAE in the top-Fe, the complex magnetic hysteresis behavior could be clearly explained. Two well-split hysteresis loops with almost zero Kerr remanence were measured by choosing a suitable Pd thickness and applying the magnetic field perpendicular to the easy axis of the bottom-Fe. The split double loops originated from the 90°-rotation of the top-Fe moment. On exposure to a hydrogen gas atmosphere, the separation of the two minor loops increased, indicating that Pd-hydride formation enhanced the ferromagnetic coupling between the two Fe layers. Based on these observations, we proposed that, by applying a suitable constant magnetic field, the top-Fe moment could undergo reversible 90°-rotation following hydrogen exposure. The results suggest that the Pd space layer used for mediating the magnetic interlayer coupling is sensitive to hydrogen, and therefore, the multilayer system can function as a giant magnetoresistance-type sensor suitable for hydrogen gas.
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Using x-ray magnetic spectroscopy with in-situ electrical characterizations, we investigated the effects of external voltage on the spin-electronic and transport properties at the interface of a Fe/ZnO device. Layer-, element-, and spin-resolved information of the device was obtained by cross-tuning of the x-ray mode and photon energy, when voltage was applied. At the early stage of the operation, the device exhibited a low-resistance state featuring robust Fe-O bonds. However, the Fe-O bonds were broken with increasing voltage. Breaking of the Fe-O bonds caused the formation of oxygen vacancies and resulted in a high-resistance state. Such interface reconstruction was coupled to a charge-transfer effect via Fe-O hybridization, which suppressed/enhanced the magnetization/coercivity of Fe electronically. Nevertheless, the interface became stabilized with the metallic phase if the device was continuously polarized. During this stage, the spin-polarization of Fe was enhanced whereas the coercivity was lowered by voltage, but changes of both characteristics were reversible. This stage is desirable for spintronic device applications, owing to a different voltage-induced electronic transition compared to the first stage. The study enabled a straightforward detection of the spin-electronic state at the ferromagnet-semiconductor interface in relation to the transport and reversal properties during operation process of the device.