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1.
J Intellect Disabil Res ; 63(9): 1111-1124, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31020725

RESUMEN

BACKGROUND: Whether individuals with autism spectrum disorder (ASD) have impairments with biological motion perception has been debated. The present study examined the ability to identify point-light-displayed (PLD) human actions in neurotypical (NT) adults and adults with ASD. METHOD: Twenty-seven adults with ASD (mean age = 28.36) and 30 NT adults (mean age = 22.45) were tested. Both groups viewed 10 different biological motion actions contacting an object/tool and 10 without making contact. Each action was presented twice, and participant's naming responses and reaction times were recorded. RESULTS: The ASD group had a significantly lower total number of correct items (M = 29.30 ± 5.08 out of 40) and longer response time (M = 4550 ± 1442 ms) than NT group (M = 32.77 ± 2.78; M = 3556 ± 1148 ms). Both groups were better at naming the actions without objects (ASD group: 17.33 ± 2.30, NT group: 18.67 ± 1.30) than those with objects (ASD group: 11.96 ± 3.57, NT group: 14.10 ± 1.97). Correlation analyses showed that individuals with higher Autism-spectrum Quotient scale scores tended to make more errors and responded more slowly. CONCLUSION: Adults with ASD were able to identify human point-light display biological motion actions much better than chance; however, they were less proficient compared with NT adults in terms of accuracy and speed, regardless of action type.


Asunto(s)
Trastorno del Espectro Autista/fisiopatología , Percepción de Movimiento/fisiología , Desempeño Psicomotor/fisiología , Adulto , Femenino , Humanos , Masculino , Adulto Joven
2.
Rhinology ; 57(4): 268-272, 2019 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-30887967

RESUMEN

BACKGROUND: Azelastine hydrochloride (azelastine) nasal spray is a histamine receptor-1 (H1) antagonist often used in treating allergic rhinitis to relieve its symptoms. However, the effects of azelastine to influence decongestion on human nasal mucosa in patients with allergic rhinitis are not yet fully explored and merit further exploration. The effects of azelastine on the vasocontractile responses generated by smooth muscles in the vascular structures of human nasal mucosa were investigated directly in vitro. METHODS: We examined the effectiveness of azelastine on isolated human nasal mucosa by testing: 1) the effect on mucosa resting tension; 2) the effect on mucosal contraction caused by 10-6 M methoxamine as a sympathetic mimetic; 3) the effect of the drugs on electrically induced mucosal contractions. RESULTS: The results indicated that addition of methoxamine to the incubation medium caused the nasal mucosa to contract in a dose-dependent manner. Addition of azelastine at doses of 10â€"6 M or above elicited a significant dilation response to 10â€"6 M methoxamine-induced mucosal contraction. Azelastine could inhibit electrical field stimulation-induced spike mucosal contraction. Moreover, increase in concentration of azelastine had minimal effect on basal tension of nasal mucosa. CONCLUSIONS: The technique in our study is simple and reproducible. Azelastine could inhibit both EFS and methoxamine-induced nasal mucosal contractions in vitro. This study highlights that although azelastine nasal spray is often used in treating allergic rhinitis to improve symptoms, nasal obstruction may be not relieved immediately due to the anti-sympathetic effect of azelastine.


Asunto(s)
Antiinflamatorios no Esteroideos , Mucosa Nasal , Ftalazinas , Rinitis Alérgica , Rinitis , Administración Intranasal , Antiinflamatorios no Esteroideos/farmacología , Antiinflamatorios no Esteroideos/uso terapéutico , Método Doble Ciego , Humanos , Mucosa Nasal/efectos de los fármacos , Rociadores Nasales , Ftalazinas/farmacología , Ftalazinas/uso terapéutico , Rinitis/tratamiento farmacológico
3.
Clin Otolaryngol ; 43(4): 1031-1035, 2018 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-29495103

RESUMEN

OBJECTIVES: Sumatriptan (Imigran) is a potent and highly selective 5-HT1 receptor agonist often used in treating acute migraine. Intranasal sumatriptan is well absorbed and is generally effective in relieving headache. However, the effects of Imigran on human nasal mucosa have rarely been well explored, to verify the effect of Imigran, which act on human nasal mucosa directly in vitro. DESIGN AND PARTICIPANTS: We examined the effectiveness of Imigran on human nasal mucosa by testing: (i) effect on human nasal mucosa resting tension; (ii) effect on contraction caused by 10-6  mol/L methoxamine as a sympathetic mimetic; and (iii) effect of the drugs on electrically induced on human nasal mucosa contractions. RESULTS: The results indicated that addition of methoxamine to the incubation medium caused the nasal mucosa to contract in a dose-dependent manner. Addition of Imigran at doses of 10-4  mol/L elicited a significant relaxation response to 10-6  mol/L methoxamine-induced contraction. Imigran could not inhibit electrical field stimulation-induced spike contraction. It also had a minimal effect on the basal tension of nasal mucosa as the concentration increased. CONCLUSIONS: The study indicated that high concentrations of Imigran had a significant spasmolytic effect by antagonising α-adreoceptors and nasal obstruction could not be released in the patient combined with acute migraine and stuffy nose by concomitant α-adrenergic agonist nasal spray plus Imigran nasal spray.

4.
Zhonghua Yu Fang Yi Xue Za Zhi ; 52(2): 145-150, 2018 Feb 06.
Artículo en Zh | MEDLINE | ID: mdl-29429268

RESUMEN

Objective: The objective was to identify the incidence of influenza-like syndromes and related health behavior factors among Beijing residents. Methods: From December 6, 2013 to January 16, 2014, we selected 150 villages or communities from 30 towns or streets as survey locations using a multi-stage random sampling method, and then conducted a cross-sectional study among 7 354 residents who aged 18 years or above and had live in Beijing for more than a half year using self-administered anonymous questionnaires, and totally 7 327 valid questionnaires are collected. The questionnaire consisted of demographic information, self-reported influenza-like syndromes in the past two weeks, and health behaviors. Multiple logistic regression models were used to identify the factors associated with self-reported influenza-like syndromes. Results: The mean (SD) age of the partcipants was 44.6 (15.2) years. Among them, 6.9% (506 cases) reported having influenza like illness during the past two weeks. The multiple logistic regression analysis indicated that regular physical exercise, optimal hand hygiene, and avoidance of going to the crowded places during respiratory infectious disease epidemics were significantly associated with a lower likelihood of reporting influenza-like syndromes, compared with those without regular physical exercises, without optimal hand hygiene, and not avoiding going to the crowded places, and the OR(95%CI) were 0.80 (0.66-0.97), 0.75 (0.57-0.99) and 0.80 (0.65-0.98), respectively. Conclusion: Personal health behaviors were associated with the incidence of respiratory infectious diseases such as influenza in Beijing, and future interventions to improve personal hygiene behaviors are needed to prevent the spread of respiratory infectious diseases.


Asunto(s)
Conductas Relacionadas con la Salud , Gripe Humana/epidemiología , Beijing , Estudios Transversales , Humanos , Incidencia , Infecciones del Sistema Respiratorio , Medio Social , Encuestas y Cuestionarios , Síndrome
5.
Proc Natl Acad Sci U S A ; 109(25): 9710-5, 2012 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-22647612

RESUMEN

The control of material interfaces at the atomic level has led to novel interfacial properties and functionalities. In particular, the study of polar discontinuities at interfaces between complex oxides lies at the frontier of modern condensed matter research. Here we employ a combination of experimental measurements and theoretical calculations to demonstrate the control of a bulk property, namely ferroelectric polarization, of a heteroepitaxial bilayer by precise atomic-scale interface engineering. More specifically, the control is achieved by exploiting the interfacial valence mismatch to influence the electrostatic potential step across the interface, which manifests itself as the biased-voltage in ferroelectric hysteresis loops and determines the ferroelectric state. A broad study of diverse systems comprising different ferroelectrics and conducting perovskite underlayers extends the generality of this phenomenon.

6.
Clin Otolaryngol ; 40(4): 355-62, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-25639297

RESUMEN

OBJECTIVE: Recent reports have identified hypercholesterolaemia as a significant risk factor for idiopathic sudden sensorineural hearing loss (ISSNHL). Therefore, we investigated whether lipid profiles and lipoprotein ratios are correlated with the prognosis of hearing recovery in ISSNHL patients. DESIGN: A retrospective cohort study. MAIN OUTCOME MEASURES: Patients with ISSNHL were classified into four groups (complete, partial, slight and no recovery) according to their degree of hearing recovery using Siegel's criteria and the Sudden Deafness Research Group (SDRG) criteria developed by the Japanese Ministry of Welfare. All patients' lipid profiles were analysed, including total cholesterol (TC), high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol and triglycerides. We calculated the ratios of TC/HDL-C and LDL-C/HDL-C and used statistical methods to evaluate correlations between lipid profiles and lipoprotein ratios and ISSNHL prognosis. RESULTS: Hearing recovery was observed in 103 (62.0%) of 166 cases using Siegel's criteria and in 114 (68.7%) of 166 cases using SDRG's criteria. Among the three recovery groups (i.e. excluding the no recovery group), the ratio of LDL-C/HDL-C was found to be associated with recovery outcome by showing the ratio on an upward trend from complete recovery to slight recovery group, and the difference is statistically significant (P = 0.016 by Siegel's criteria, P = 0.041 by SDRG's criteria). Multiple linear regression analysis further revealed a significantly higher LDL-C/HDL-C ratio in slight hearing recovery group compared with complete recovery group (P = 0.007 by Siegel's criteria, P = 0.031 by SDRG's criteria). CONCLUSION: We suggested that lipoprotein ratio of LDL-C/HDL-C may be a prognostic factor for hearing recovery in ISSNHL patients. Further studies should be conducted to determine whether hearing outcomes in ISSNHL can be improved by changing patients' lipid profiles via antilipidemic treatment.


Asunto(s)
Pérdida Auditiva Sensorineural/etiología , Pérdida Auditiva Súbita/etiología , Hiperlipidemias/complicaciones , Femenino , Pérdida Auditiva Sensorineural/clasificación , Pérdida Auditiva Súbita/clasificación , Humanos , Lipoproteínas HDL/sangre , Lipoproteínas LDL/sangre , Masculino , Persona de Mediana Edad , Pronóstico , Estudios Retrospectivos , Factores de Riesgo , Resultado del Tratamiento
7.
Rhinology ; 52(3): 208-14, 2014 09.
Artículo en Inglés | MEDLINE | ID: mdl-25271525

RESUMEN

OBJECTIVES: The frontal sinus has the most complex and variable drainage routes of all paranasal sinus regions. The goal of this study was to identify these anatomical factors and inflammation areas relating to chronic frontal sinusitis by comparing radiological presentations in patients with and without frontal sinusitis. METHODS: All adult patients with chronic rhinosinusitis who had received computed tomography (CT) scans of the nasal cavities and paranasal sinuses between October 2010 and September 2011. Logistic regression analysis was used to compare the distribution of various frontal recess cells and surrounding inflammatory conditions in patients with and without frontal sinusitis. RESULTS: Analysis of 240 sides of CT scans was performed with 66 sides excluded. The opacification of the frontal recess and sinus lateralis demonstrated a strong association with an increased presence of frontal sinusitis by multiple logistic regression models. CONCLUSION: Opacification of the frontal recess and sinus lateralis was found to be associated with a significantly increased risk of frontal sinusitis and developing severe blockage of drainage pathways. It provides evidence that mucosal inflammation disease in these two areas is a very important factor leading to chronic frontal sinusitis.


Asunto(s)
Seno Frontal/diagnóstico por imagen , Seno Frontal/patología , Sinusitis Frontal/diagnóstico por imagen , Sinusitis Frontal/patología , Membrana Mucosa/diagnóstico por imagen , Membrana Mucosa/patología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Enfermedad Crónica , Femenino , Seno Frontal/anatomía & histología , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Tomografía Computarizada por Rayos X , Adulto Joven
8.
Nano Lett ; 13(4): 1410-5, 2013 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-23418908

RESUMEN

The performance of ferroelectric devices, for example, the ferroelectric field effect transistor, is reduced by the presence of crystal defects such as edge dislocations. For example, it is well-known that edge dislocations play a crucial role in the formation of ferroelectric dead-layers at interfaces and hence finite size effects in ferroelectric thin films. The detailed lattice structure including the relevant electromechanical coupling mechanisms in close vicinity of the edge dislocations is, however, not well-understood, which hampers device optimization. Here, we investigate edge dislocations in ferroelectric BiFeO3 by means of spherical aberration-corrected scanning transmission electron microscopy, a dedicated model-based structure analysis, and phase field simulations. Unit-cell-wise resolved strain and polarization profiles around edge dislocation reveal a wealth of material states including polymorph nanodomains and multiple domain walls characteristically pinned to the dislocation. We locally determine the piezoelectric tensor and identify piezoelectric coupling as the driving force for the observed phenomena, explaining, for example, the orientation of the domain wall with respect to the edge dislocation. Furthermore, an atomic model for the dislocation core is derived.


Asunto(s)
Berilio/química , Electricidad , Compuestos Férricos/química , Nanoestructuras/química , Microscopía Electrónica de Transmisión de Rastreo , Tamaño de la Partícula , Transistores Electrónicos
9.
Rhinology ; 51(4): 376-80, 2013 12.
Artículo en Inglés | MEDLINE | ID: mdl-24260772

RESUMEN

OBJECTIVES: Histamine is an important chemical mediator in both nasal and bronchial inflammation in patients with allergic rhinitis and asthma. The effect of histamine receptor-1 antagonists on nasal mucosa in vivo is well known, however, the effect on tracheal smooth muscle has rarely been explored. The purpose of this study was to determine the effects of fexofenadine on isolated tracheal smooth muscle in vitro. METHODS: Six tracheal strips were used for each experiment, and one untreated strip served as a control. We examined the effectiveness of fexofenadine on isolated rat tracheal smooth muscle by testing the effect on: 1) tracheal smooth muscle resting tension; 2) contraction caused by 10E-6 M methacholine as a parasympathetic mimetic; and 3) electrically induced tracheal smooth muscle contractions. RESULTS: The results indicated that addition of methacholine caused the trachea to contract in a dose-dependent manner. The addition of fexofenadine at a dose of 10E-4 M elicited a significant relaxation response compared to 10E-6 M methacholine-induced contraction. There were no detectable changes in the peak tension of electrical field stimulation-induced contractions in the fexofenadine group. CONCLUSION: High concentrations of fexofenadine had an anti-cholinergic effect. In addition to diminishing histamine-mediated allergic symptoms, fexofenadine may have a potentially therapeutic implication in alleviating asthma-related symptoms due to reducing methacholine-induced contractions of tracheal smooth muscle though these aspects were not studied.


Asunto(s)
Antagonistas de los Receptores Histamínicos H1 no Sedantes/farmacología , Músculo Liso/efectos de los fármacos , Terfenadina/análogos & derivados , Tráquea/efectos de los fármacos , Animales , Estimulación Eléctrica , Contracción Muscular/efectos de los fármacos , Tono Muscular/efectos de los fármacos , Músculo Liso/fisiología , Ratas , Terfenadina/farmacología , Técnicas de Cultivo de Tejidos , Tráquea/fisiología
10.
Nano Lett ; 12(11): 5524-31, 2012 Nov 14.
Artículo en Inglés | MEDLINE | ID: mdl-22994244

RESUMEN

A new paradigm of domain wall nanoelectronics has emerged recently, in which the domain wall in a ferroic is itself an active device element. The ability to spatially modulate the ferroic order parameter within a single domain wall allows the physical properties to be tailored at will and hence opens vastly unexplored device possibilities. Here, we demonstrate via ambient and ultrahigh-vacuum (UHV) scanning probe microscopy (SPM) measurements in bismuth ferrite that the conductivity of the domain walls can be modulated by up to 500% in the spatial dimension as a function of domain wall curvature. Landau-Ginzburg-Devonshire calculations reveal the conduction is a result of carriers or vacancies migrating to neutralize the charge at the formed interface. Phase-field modeling indicates that anisotropic potential distributions can occur even for initially uncharged walls, from polarization dynamics mediated by elastic effects. These results are the first proof of concept for modulation of charge as a function of domain wall geometry by a proximal probe, thereby expanding potential applications for oxide ferroics in future nanoscale electronics.


Asunto(s)
Conductividad Eléctrica , Anisotropía , Elasticidad , Electricidad , Electrónica , Iones , Cinética , Microscopía de Fuerza Atómica/métodos , Microscopía de Sonda de Barrido/métodos , Modelos Estadísticos , Óxidos/química , Oxígeno/química , Semiconductores , Termodinámica
11.
J Nutr Health Aging ; 27(6): 487-595, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37357334

RESUMEN

OBJECTIVES: There is little evidence in the literature about the relationship between frailty and falls in older adults. Our objective was to explore the relationship between frailty and falls, and to analyze the effect factors (e.g., gender, different frailty assessment tools, areas, level of national economic development, and year of publication) of the association between frailty and falls among older adults. DESIGN: Systematic review and meta-analysis. SETTING AND PARTICIPANTS: Cohort studies that evaluated the association between frailty and falls in the older adults were included. We excluded any literature outside of cohort studies. METHODS: We did a systematic literature search of English databases PubMed, Scopus, Web of Science, EBSCOhost, and SciElO, as well as the Chinese databases CNKI, WANFANG, and VIP from 2001 until October 2022. The eligible studies were evaluated for potential bias using the Newcastle-Ottawa Scale (NOS). Study selection, data extraction and assessment of study quality were each conducted by two investigators. In Stata/MP 17.0 software, we calculated pooled estimates of the prevalence of falls by using a random-effects model, Subgroup analysis was conducted based on gender, different frailty assessment tools, areas, level of economic development, and year of publication. The results are presented using a forest plot. RESULTS: Twenty-nine studies were included in this meta-analysis and a total of 1,093,270 participants aged 65 years and above were enrolled. Among the older adults, frailty was significantly associated with a higher risk for falls, compared with those without frailty (combined RR-relative risk = 1.48, 95% CI-confidence interval: 1.27-1.73, I2=98.9%). In addition, the results of subgroup analysis indicated that men had a higher risk for falls than women among the older adults with frailty (RR 1.94, 95% CI: 1.18-3.2 versus RR 1.44, 95% CI: 1.24-1.67). Subgroup analysis by different frailty assessment tools revealed an increased risk of falls in older adults with frailty when assessed using the Frailty Phenotype (combined RR 1.32, 95%CI: 1.17-1.48), FRAIL score (combined RR 1.82, 95%CI: 1.36-2.43), and Study of Osteoporotic Fractures index (combined RR 1.54, 95%CI: 1.10-2.16). Furthermore, subgroup analysis by areas and level of national economic development found the highest fall risk in Oceania (combined RR 2.35, 95%CI: 2.28-2.43) and the lowest in Europe (combined RR 1.20, 95%CI: 1.05-1.38). Developed countries exhibited a lower fall risk compared to developing countries (combined RR 1.44, 95%CI: 1.21-1.71). Analysis by year of publication showed the highest fall risk between 2013-2019 (combined RR 1.79, 95%CI: 1.45-2.20) and the lowest between 2001-2013 (combined RR 1.21, 95%CI: 1.13-1.29). CONCLUSION: Frailty represents a significant risk factor for falls in older adults, with the degree of risk varying according to the different frailty assessment tools employed, and notably highest when using the FRAIL scale. Additionally, factors such as gender, areas, level of national economic development, and healthcare managers' understanding of frailty may all impact the correlation between frailty and falls. Thus, it's imperative to select suitable frailty diagnostic tools tailored to the specific characteristics of the population in question. This, in turn, facilitates the accurate identification of frailty in older adults and informs the development of appropriate preventive and therapeutic strategies to mitigate fall risk.


Asunto(s)
Fracturas Óseas , Fragilidad , Femenino , Humanos , Accidentes por Caídas/prevención & control , Fragilidad/epidemiología , Factores de Riesgo , Estudios de Cohortes
12.
Opt Lett ; 37(6): 1112-4, 2012 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-22446242

RESUMEN

A visible-blind UV photodetector (PD) using a double heterojunction of n-ZnO/LaAlO3 (LAO)/p-Si was demonstrated. Inserted LAO layers exhibit electrical insulating properties and serve as blocking layers for photoexcited electrons from p-Si to n-ZnO, leading to an enhanced rectification ratio and a visible-blind UV detectivity of the n-ZnO/LAO/p-Si PDs due to the high potential barrier between LAO and p-Si layers (~2.0 eV). These results support the use of n-ZnO/LAO/p-Si PDs in the visible-blind UV PDs in a visible-light environment.

13.
Phys Rev Lett ; 109(4): 047601, 2012 Jul 27.
Artículo en Inglés | MEDLINE | ID: mdl-23006107

RESUMEN

Domain walls (DWs) substantially influence a large number of applications involving ferroelectric materials due to their limited mobility when shifted during polarization switching. The discovery of greatly enhanced conduction at BiFeO(3) DWs has highlighted yet another role of DWs as a local material state with unique properties. However, the lack of precise information on the local atomic structure is still hampering microscopical understanding of DW properties. Here, we examine the atomic structure of BiFeO(3) 109° DWs with pm precision by a combination of high-angle annular dark-field scanning transmission electron microscopy and a dedicated structural analysis. By measuring simultaneously local polarization and strain, we provide direct experimental proof for the straight DW structure predicted by ab initio calculations as well as the recently proposed theory of diffuse DWs, thus resolving a long-standing discrepancy between experimentally measured and theoretically predicted DW mobilities.

14.
Phys Rev Lett ; 108(6): 067203, 2012 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-22401116

RESUMEN

Domain walls in multiferroics can exhibit intriguing behaviors that are significantly different from the bulk of the material. We investigate strong magnetoresistance in domain walls of the model multiferroic BiFeO3 by probing ordered arrays of 109° domain walls with temperature- and magnetic-field-dependent transport. We observe temperature-dependent variations in the transport mechanism and magnetoresistances as large as 60%. These results suggest that by locally breaking the symmetry of a material, such as at domain walls and structural interfaces, one can induce emergent behavior with properties that deviate significantly from the bulk.

15.
Phys Rev Lett ; 109(24): 247606, 2012 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-23368382

RESUMEN

A new orthorhombic phase of the multiferroic BiFeO3 has been created via strain engineering by growing it on a NdScO(3)(110)(o) substrate. The tensile-strained orthorhombic BiFeO3 phase is ferroelectric and antiferromagnetic at room temperature. A combination of nonlinear optical second harmonic generation and piezoresponse force microscopy revealed that the ferroelectric polarization in the orthorhombic phase is along the in-plane {110}(pc) directions. In addition, the corresponding rotation of the antiferromagnetic axis in this new phase was observed using x-ray linear dichroism.

16.
Trop Biomed ; 39(3): 434-443, 2022 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-36214441

RESUMEN

The larvae of Echinococcus (hydatidcyst) can parasitize humans and animals, causing a serious zoonotic disease-echinococcosis. The life history of Echinococcus is complicated, and as the disease progresses slowly after infection, early diagnosis is difficult to establish. Due to the limitations of imaging and immunological diagnosis in this respect, domestic and foreign scholars have established a variety of molecular detection techniques for the pathogen Echinococcus over recent years, mainly including nested polymerase chain reaction (PCR), multiplex PCR, real-time quantitative PCR, and nucleic acid isothermal amplification technology. In this article, the research progress of molecular detection technology for Echinococcus infection currently was reviewed and the significance of these methods in the detection and diagnosis of hydatid and hydatid diseases was also discussed.


Asunto(s)
Equinococosis , Echinococcus , Ácidos Nucleicos , Animales , Equinococosis/diagnóstico , Echinococcus/genética , Humanos , Reacción en Cadena de la Polimerasa Multiplex/métodos , Sensibilidad y Especificidad , Tecnología
17.
Nat Mater ; 9(4): 309-14, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20190772

RESUMEN

Multiferroics, where (anti-) ferromagnetic, ferroelectric and ferroelastic order parameters coexist, enable manipulation of magnetic ordering by an electric field through switching of the electric polarization. It has been shown that realization of magnetoelectric coupling in a single-phase multiferroic such as BiFeO(3) requires ferroelastic (71 degrees, 109 degrees) rather than ferroelectric (180 degrees) domain switching. However, the control of such ferroelastic switching in a single-phase system has been a significant challenge as elastic interactions tend to destabilize small switched volumes, resulting in subsequent ferroelastic back-switching at zero electric field, and thus the disappearance of non-volatile information storage. Guided by our phase-field simulations, here we report an approach to stabilize ferroelastic switching by eliminating the stress-induced instability responsible for back-switching using isolated monodomain BiFeO(3) islands. This work demonstrates a critical step to control and use non-volatile magnetoelectric coupling at the nanoscale. Beyond magnetoelectric coupling, it provides a framework for exploring a route to control multiple order parameters coupled to ferroelastic order in other low-symmetry materials.

18.
Phys Rev Lett ; 107(21): 217202, 2011 Nov 18.
Artículo en Inglés | MEDLINE | ID: mdl-22181917

RESUMEN

A reversal of magnetization requiring only the application of an electric field can lead to low-power spintronic devices by eliminating conventional magnetic switching methods. Here we show a nonvolatile, room temperature magnetization reversal determined by an electric field in a ferromagnet-multiferroic system. The effect is reversible and mediated by an interfacial magnetic coupling dictated by the multiferroic. Such electric-field control of a magnetoelectric device demonstrates an avenue for next-generation, low-energy consumption spintronics.

19.
Phys Rev Lett ; 106(18): 186404, 2011 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-21635110

RESUMEN

We present resonant soft x-ray scattering results from small bandwidth manganites (Pr,Ca)MnO(3), which show that the CE-type spin ordering (SO) at the phase boundary is stabilized only below the canted antiferromagnetic transition temperature and enhanced by ferromagnetism in the macroscopically insulating state (FM-I). Our results reveal the fragility of the CE-type ordering that underpins the colossal magnetoresistance effect in this system, as well as an unexpected cooperative interplay between FM-I and CE-type SO which is in contrast to the competitive interplay between the ferromagnetic metallic state and CE-type ordering.

20.
Phys Rev Lett ; 107(14): 147602, 2011 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-22107234

RESUMEN

We report direct experimental evidence for a room-temperature, ∼130 µC/cm(2) ferroelectric polarization from the tetragonal-like BiFeO(3) phase. The physical origin of this remarkable enhancement of ferroelectric polarization has been investigated by a combination of x-ray absorption spectroscopy, scanning transmission electron microscopy, and first principles calculations. A large strain-induced Fe-ion displacement relative to the oxygen octahedra, combined with the contribution of Bi 6s lone pair electrons, is the mechanism driving the large ferroelectric polarization in this tetragonal-like phase.

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