Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 55
Filtrar
Más filtros

Banco de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Nature ; 633(8031): 798-803, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39261737

RESUMEN

Materials with electromechanical coupling are essential for transducers and acoustic devices as reversible converters between mechanical and electrical energy1-6. High electromechanical responses are typically found in materials with strong structural instabilities, conventionally achieved by two strategies-morphotropic phase boundaries7 and nanoscale structural heterogeneity8. Here we demonstrate a different strategy to accomplish ultrahigh electromechanical response by inducing extreme structural instability from competing antiferroelectric and ferroelectric orders. Guided by the phase diagram and theoretical calculations, we designed the coexistence of antiferroelectric orthorhombic and ferroelectric rhombohedral phases in sodium niobate thin films. These films show effective piezoelectric coefficients above 5,000 pm V-1 because of electric-field-induced antiferroelectric-ferroelectric phase transitions. Our results provide a general approach to design and exploit antiferroelectric materials for electromechanical devices.

2.
Phys Rev Lett ; 133(6): 066503, 2024 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-39178458

RESUMEN

Topotactic reduction utilizing metal hydrides as reagents has emerged as an effective approach to achieve exceptionally low oxidization states of metal ions and unconventional coordination networks. This method opens avenues to the development of entirely new functional materials, with one notable example being the infinite-layer nickelate superconductors. However, the reduction effect on the atomic reconstruction and electronic structures-crucial for superconductivity-remains largely unresolved. We designed two sets of control Nd_{0.8}Sr_{0.2}NiO_{2} thin films and used secondary ion mass spectroscopy to highlight the absence of reduction-induced hydrogen intercalation. X-ray absorption spectroscopy revealed a significant linear dichroism with dominant Ni 3d_{x2-y2} orbitals on superconducting samples, indicating a Ni single-band nature of infinite-layer nickelates. Consistent with the superconducting T_{c}, the Ni 3d orbitals asymmetry manifests a domelike dependence on the reduction duration. Our results unveil the critical role of reduction in modulating the Ni-3d orbital polarization and its impact on the superconducting properties.

3.
Sensors (Basel) ; 23(6)2023 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-36991805

RESUMEN

Traces of mercury ions in environmental water can harm humans and animals. Paper-based visual detection methods have been widely developed for the rapid detection of mercury ions; however, existing methods are not sensitive enough to be used in real environments. Here, we developed a novel, simple and effective visual fluorescent sensing paper-based chip for the ultrasensitive detection of mercury ions in environmental water. CdTe-quantum-dots-modified silica nanospheres were firmly absorbed by and anchored to the fiber interspaces on the paper's surface to effectively avoid the unevenness caused by liquid evaporation. The fluorescence of quantum dots emitted at 525 nm can be selectively and efficiently quenched with mercury ions, and the ultrasensitive visual fluorescence sensing results attained using this principle can be captured using a smartphone camera. This method has a detection limit of 2.83 µg/L and a fast response time (90 s). We successfully achieved the trace spiking detection of seawater (from three regions), lake water, river water and tap water with recoveries in the range of 96.8-105.4% using this method. This method is effective, low-cost, user-friendly and has good prospects for commercial application. Additionally, the work is expected to be utilized in the automated big data collection of large numbers of environmental samples.

4.
Phys Rev Lett ; 129(23): 235701, 2022 Dec 02.
Artículo en Inglés | MEDLINE | ID: mdl-36563221

RESUMEN

Understanding the behavior of defects in the complex oxides is key to controlling myriad ionic and electronic properties in these multifunctional materials. The observation of defect dynamics, however, requires a unique probe-one sensitive to the configuration of defects as well as its time evolution. Here, we present measurements of oxygen vacancy ordering in epitaxial thin films of SrCoO_{x} and the brownmillerite-perovskite phase transition employing x-ray photon correlation spectroscopy. These and associated synchrotron measurements and theory calculations reveal the close interaction between the kinetics and the dynamics of the phase transition, showing how spatial and temporal fluctuations of heterointerface evolve during the transformation process. The energetics of the transition are correlated with the behavior of oxygen vacancies, and the dimensionality of the transformation is shown to depend strongly on whether the phase is undergoing oxidation or reduction. The experimental and theoretical methods described here are broadly applicable to in situ measurements of dynamic phase behavior and demonstrate how coherence may be employed for novel studies of the complex oxides as enabled by the arrival of fourth-generation hard x-ray coherent light sources.

5.
Nature ; 534(7606): 231-4, 2016 06 09.
Artículo en Inglés | MEDLINE | ID: mdl-27279218

RESUMEN

Fuel cells convert chemical energy directly into electrical energy with high efficiencies and environmental benefits, as compared with traditional heat engines. Yttria-stabilized zirconia is perhaps the material with the most potential as an electrolyte in solid oxide fuel cells (SOFCs), owing to its stability and near-unity ionic transference number. Although there exist materials with superior ionic conductivity, they are often limited by their ability to suppress electronic leakage when exposed to the reducing environment at the fuel interface. Such electronic leakage reduces fuel cell power output and the associated chemo-mechanical stresses can also lead to catastrophic fracture of electrolyte membranes. Here we depart from traditional electrolyte design that relies on cation substitution to sustain ionic conduction. Instead, we use a perovskite nickelate as an electrolyte with high initial ionic and electronic conductivity. Since many such oxides are also correlated electron systems, we can suppress the electronic conduction through a filling-controlled Mott transition induced by spontaneous hydrogen incorporation. Using such a nickelate as the electrolyte in free-standing membrane geometry, we demonstrate a low-temperature micro-fabricated SOFC with high performance. The ionic conductivity of the nickelate perovskite is comparable to the best-performing solid electrolytes in the same temperature range, with a very low activation energy. The results present a design strategy for high-performance materials exhibiting emergent properties arising from strong electron correlations.

6.
Ecotoxicol Environ Saf ; 239: 113628, 2022 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-35576801

RESUMEN

Fomesafen is the most widely used herbicide in the soybean field. However, there are urgent practical challenges with the long-term persistence of fomesafen in soil and its effects on the subsequent crops in agricultural production. Therefore, pot experiments were conducted to study the effects of fomesafen residues (0-0.05 mg kg-1) on growth, photosynthetic characteristics, and the antioxidant defense system of sugar beet seedlings. The results showed that with the increase of fomesafen residues, the phytotoxicity index increased, while the plant height, leaf area, root length, root volume, and dry weight of sugar beet decreased. Photosynthetic pigment content, net photosynthetic rate (Pn), maximum photosynthetic efficiency (Fv/Fm), and actual photosynthetic efficiency (Y(II)) declined with a dose-dependent manner of fomesafen, but the intercellular CO2 concentration (Ci) and non-photochemical quenching coefficient (NPQ) increased under fomesafen. On the other hand, the residues of fomesafen increased the content of malondialdehyde (MDA) and membrane permeability by aggravating oxidative stress and triggering the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and polyphenol oxidase (PPO). In addition, sugar beet seedlings were significantly sensitive to fomesafen as the concentration of fomesafen in the soil was up to 0.025 mg kg-1. In conclusion, the present study showed that fomesafen residues in the soil could affect the morphophysiology and photosynthetic performance of sugar beet. This study is beneficial for understanding the effects of the herbicide fomesafen residues on non-target crops.


Asunto(s)
Beta vulgaris , Herbicidas , Benzamidas , Clorofila/farmacología , Herbicidas/toxicidad , Fotosíntesis , Hojas de la Planta , Plantones , Suelo/química , Azúcares
7.
Ecotoxicol Environ Saf ; 238: 113587, 2022 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-35512468

RESUMEN

Fomesafen herbicide application has become major pollution in the growth and production of crops. Spraying fomesafen on the target crops may drift out to non-target crops. In northeast China, sugar beets are always planted adjacent to soybeans. Salicylic acid (SA) plays an important role in crop growth and alleviating abiotic stress, however, the role of SA in relieving fomesafen stress in sugar beet growth has rarely been investigated. Therefore, a pot study was conducted to elucidate the effects of different concentrations (0.025, 0.25, 0.5, 1, 5, and 10 mM) of SA on morphological parameters, photosynthetic performance, and antioxidant defense system in sugar beet seedlings under fomesafen (22.5 g a.i. ha-1) stress. The results showed that fomesafen stress inhibited the growth of sugar beet seedlings, and photosynthetic performance, while increased membrane lipid peroxidation and oxidative stress. However, exogenous SA alleviated the fomesafen stress and increased plant height, biomass, photosynthetic pigment contents, net photosynthetic rate (Pn), and photochemical efficiency of PSⅡ (Fv/Fm) in sugar beet leaves. Meanwhile, exogenous SA maintained the cell membrane integrity by reducing the content of malondialdehyde (MDA) and electrolyte permeability and regulating the activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and polyphenol (PPO). Therefore, it is concluded that exogenous SA ameliorated the adverse effects of fomesafen on the growth of sugar beet seedlings, with a pronounced effect at 1 mM SA. The present study results may have useful implications in managing other plants that are poisoned by herbicides.


Asunto(s)
Antioxidantes , Beta vulgaris , Antioxidantes/metabolismo , Benzamidas , Beta vulgaris/metabolismo , Clorofila/metabolismo , Fotosíntesis , Hojas de la Planta/metabolismo , Ácido Salicílico/metabolismo , Ácido Salicílico/farmacología , Plantones , Azúcares/metabolismo
8.
Ecotoxicol Environ Saf ; 248: 114295, 2022 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-36402074

RESUMEN

This sugar beet acts as a soil remediator in areas where there are high levels of boron (B) in the soil, since it has a high requirement of boron (B) for growth, and has strong resistance to high B levels. Although B toxicity in different plants has been widely researched, little is known about the response of photosystem II (PSII) activity in sugar beet leaves to B toxicity at present. To clarify the growth and photosynthetic physiological response of sugar beet to B toxicity, the effects of different concentrations of H3BO3 (0.05, 1.5, 2.5,3.5 mM) on the growth, photosynthetic characteristics and antioxidant defense system of sugar beet seedlings were investigated by hydroponic experiments. In the present study, high B stress inhibited the growth of sugar beet and significantly decreased the biomass of the plants. There was a remarkable increase in the accumulation of B in the shoots, which affected photosynthesis and decreased the photosynthetic pigments. As B toxicity increased, leaf PSII activities and maximum photochemical efficiency of PSII (Fv/Fm) showed a tendency to decrease; at the same time, the photosynthetic performance index based on absorbed light energy (PIABS) decreased as well. Meanwhile, the energy allocation parameters of the PSII reaction center were changed, the light energy utilization capacity and the energy used for electron transfer were reduced and the thermal dissipation was increased at the same time. Furthermore, B toxicity decreased catalase (CAT) activity, increased peroxidase (POD) and superoxide dismutase (SOD) activities, and increased malondialdehyde (MDA) accumulation. According to the results obtained in this study, high B concentrations reduced the rate of photosynthesis and fluorescence, thus weakened antioxidant defense systems, and therefore inhibited the growth of sugar beet plants. Thus, in high B areas, sugar beet possesses excellent tolerance to high B levels and has a high B translocation capacity, so it can be used as a phytoremediation tool. This study provides a basis for the feasibility of sugar beet resistant to high B environments.


Asunto(s)
Beta vulgaris , Complejo de Proteína del Fotosistema II , Boro/toxicidad , Antioxidantes , Verduras , Suelo , Azúcares
9.
Sensors (Basel) ; 19(7)2019 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-30986986

RESUMEN

Tracking maneuvering targets is a challenging problem for sensors because of the unpredictability of the target's motion. Unlike classical statistical modeling of target maneuvers, a simultaneous optimization and feedback learning algorithm for maneuvering target tracking based on the Elman neural network (ENN) is proposed in this paper. In the feedback strategy, a scale factor is learnt to adaptively tune the dynamic model's error covariance matrix, and in the optimization strategy, a corrected component of the state vector is learnt to refine the final state estimation. These two strategies are integrated in an ENN-based unscented Kalman filter (UKF) model called ELM-UKF. This filter can be trained online by the filter residual, innovation and gain matrix of the UKF to simultaneously achieve maneuver feedback and an optimized estimation. Monte Carlo experiments on synthesized radar data showed that our algorithm had better performance on filtering precision compared with most maneuvering target tracking algorithms.

10.
Pediatr Hematol Oncol ; 32(2): 92-8, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24684295

RESUMEN

Hyperbilirubinemia is prevalent in newborns and multiple factors are responsible for the occurrence of neonatal hyperbilirubinemia. G6PD (Glucose-6-Phosphate Dehydrogenase) deficiency is recognized as one of the risk factors. However, many pediatricians did not take into account the probable effect of G6PD-deficiency when severe neonatal hyperbilirubinemia occurred. The aim of the present study was to perform a meta-analysis to investigate whether G6PD-deficiency increases the risk of hyperbilirubinemia and phototherapy in newborn. We searched PubMed and Embase databases for eligible articles according to explicit study inclusion and exclusion criteria. Risk ratios (RRs) and 95% confidence interval (CI) were selected as the evaluation indexes. Cochrane Q and I(2) test were utilized to assess the heterogeneity among studies. A total of five cohort studies were included in this meta-analysis. There were 21,585 participants enrolled in these studies including 877 newborns with hyperbilirubinemia and 261 newborns receiving phototherapy. Comparison of the incidence of hyperbilirubinemia in newborns with G6PD-deficiency to the ones with normal G6PD in each study yielded a pooled RR of 3.92 (95% CI, 2.13-7.20; P <.0001). The pooled RR of receiving phototherapy in G6PD-deficiency neonates is 3.01 (95% CI, 2.20-4.12; P <.0001) when compared to G6PD normal neonates. This study revealed a significant correlation between G6PD-deficiency and neonatal hyperbilirubinemia, as well as G6PD-deficiency and phototherapy. G6PD-deficient newborns have higher risk of hyperbilirubinemia and phototherapy than the ones with normal G6PD. Monitoring the level of G6PD in newborns is important for predicting the occurrence of hyperbilirubinemia.


Asunto(s)
Deficiencia de Glucosafosfato Deshidrogenasa , Hiperbilirrubinemia , Trastornos de la Nutrición del Lactante , Fototerapia , Femenino , Deficiencia de Glucosafosfato Deshidrogenasa/epidemiología , Deficiencia de Glucosafosfato Deshidrogenasa/terapia , Humanos , Hiperbilirrubinemia/epidemiología , Hiperbilirrubinemia/terapia , Trastornos de la Nutrición del Lactante/epidemiología , Trastornos de la Nutrición del Lactante/terapia , Recién Nacido , Masculino
11.
Pak J Med Sci ; 31(5): 1172-5, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26649008

RESUMEN

OBJECTIVE: To evaluate the therapeutic effects of probiotics on neonatal jaundice and the safety. METHODS: Sixty-eight neonates with jaundice were divided into a control group and a treatment group (n=34) randomly, and treated by blue light phototherapy and that in combination with probiotics. The serum bilirubin levels were detected before and 1, 4, 7 days after treatment. The time when therapy showed effects and jaundice faded, clinical outcomes as well as adverse reactions were recorded. The categorical data were expressed as (±s) and compared by t test. The numerical data were expressed as (case, %) and compared by χ² test. P<0.05 was considered statistically significant. RESULTS: Serum bilirubin levels of the two groups were similar before treatment (P>0.05). The levels significantly decreased 1, 4 and 7 days after treatment (P<0.05), but there was no significant inter-group difference on the post-treatment 1st day (P>0.05). The treatment group underwent more significant decreases on the 4th and 7th days than the control group did (P=0.002, 0.001). In the treatment group, the therapy exerted effects on (1.0±0.5) d and jaundice faded on (3.8±1.7) d, which were (2.6±0.6) d and (5.3±2.1) d respectively in the control group (P=0.001, 0.002). The effective rate of the treatment group significantly exceeded that of the control group (P=0.002). There were no obvious adverse reactions in either group. CONCLUSIONS: Probiotics lowered the serum bilirubin levels of neonates with jaundice rapidly, safely and significantly, and accelerated jaundice fading as well. This method is worthy of application in clinical practice.

12.
Sci Rep ; 14(1): 23948, 2024 10 14.
Artículo en Inglés | MEDLINE | ID: mdl-39397085

RESUMEN

This study investigates whether duration of working hours affect residents' preferences for the micro-features of Small Urban Green Spaces (SUGS), and explores differences across genders and visitation purposes. Little is known about this subject, yet it is crucial for creating more equitable green spaces. In phase 1, participants (n = 209; 30.9 ± 6.73 years, 59.3%male) were categorized by average daily working hours (0-8 h, 8-10 h, 10 h+), and rated 41 micro-feature images on their importance for visiting SUGS. Phase 2 included the top ten features ranked from phase 1, with participants (n = 256; 30.8 ± 5.12 years, 35.2% female) completing the Kano model survey to identify and explain the importance of features and different types of needs. Findings reveal a clear trend: extended work hours pivot resident preferences towards green space attributes promoting physical activity. For residents of 0-8 h valued aesthetic elements like sculptures and vegetation, while lighting became paramount for those with 8-10 h, and for those working over 10 h prioritized facilities for active engagement, such as playground equipment and slow runway. These distinctions provide valuable guidance for designing SUGS with diverse feature combinations that cater to the needs of residential areas with varying socio-economic backgrounds and occupational lifestyles, thereby enhancing urban livability.


Asunto(s)
Población Urbana , Humanos , Femenino , Masculino , Adulto , Encuestas y Cuestionarios , Ejercicio Físico , Parques Recreativos , Ciudades , Adulto Joven , Planificación Ambiental
13.
Environ Pollut ; 351: 124041, 2024 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-38685552

RESUMEN

The use of surfactants is crucial for the prevention and control of coal dust pollution in coal mining operation areas, yet there still exist many challenges in the control of coal dust pollution. In this paper, the green biomass-based amino acid surfactant sodium myristoyl glutamate (SMG) and the anionic surfactant sodium α-alkenyl sulfonate (AOS) were selected to investigate the improvement of coal dust wettability by single and binary solutions from the macroscopic and microscopic perspectives. Molecular simulations were used to reveal the microscopic mechanism of the wettability of coal dust by the different solutions. Experimental measurements showed that the contact angle of the AOS + SMG aqueous solution was as low as 13.8° on a coal surface. Coating the coal dust with the AOS + SMG solution reduced the surface tension by 12.02% compared to coating the coal with a single component solution. Additionally, the use of the binary AOS + SMG solution increased the hydrophilic group content in the coating by 11.77% compared to a single component solution, and the linkage between hydrophilic groups was enhanced, which pulls the water molecules to wet the coal dust. These research results should provide a new way to promote more environmentally friendly coal dust pollution control technology.


Asunto(s)
Carbón Mineral , Polvo , Tensoactivos , Polvo/análisis , Tensoactivos/química , Aminoácidos/química , Humectabilidad , Alcanosulfonatos/química , Minas de Carbón , Contaminación Ambiental/prevención & control
14.
Rev Sci Instrum ; 95(3)2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38441429

RESUMEN

Superconducting magnets are widely used in nuclear fusion reactors, high-energy particle accelerators, steady-state high magnetic fields, etc. Higher magnetic fields and higher operating temperatures are two application trends. High temperature superconducting (HTS) materials are the only choice for high temperature and high field magnets in the future. The first- and second-generation HTS materials have a typical tape structure; their critical performance is magnetic field angle and temperature dependent. A new test facility is developed for an experimental study on the an-isotropic critical current. The field angle can be changed from 0° to 360° with a resolution of 1°. The rotation deviation angle is measured to be 0.2° when the upper part rotates 90°. The temperature can be changed from 4.2 to 80 K. The temperature errors are ±50, ±80, and ±135 mK for 4.2-20, 20-40, and 40-80 K, respectively. The angle dependence of critical current (Ic) of the tested rare-earth barium copper oxide tape within 0°-30° is strong. From 30° to 90°, the sample Ic almost does not change with the magnetic field angle. The implementation of the project will not only promote the structural optimization of HTS tapes but also promote the miniaturization and economical application of HTS magnets.

15.
Microsyst Nanoeng ; 10(1): 130, 2024 Sep 19.
Artículo en Inglés | MEDLINE | ID: mdl-39300103

RESUMEN

The first-order antisymmetric (A1) mode lamb wave resonator (LWR) based on Z-cut LiNbO3 thin films has attracted significant attention and is widely believed to be a candidate for next-generation reconfigurable filters with high frequency and large bandwidth (BW). However, it is challenging for traditional interdigitated electrodes (IDTs) based LWR filters to meet the requirement of a clean frequency spectrum response and enough out-of-band (OoB) rejection. To solve the problem, we propose LWRs with checker-shaped IDTs for the design of filters that meet the Wi-Fi 6E standard. By taking advantage of checker-shaped IDTs with unparalleled boundaries, the fabricated 6-GHz resonators successfully suppress higher-order A1 spurious modes, demonstrating a spurious-free impedance response and a high figure-of-merit (FOM) up to 104. Based on the demonstrated checker-shaped electrode design, the filter features a center frequency (f0) of more than 6 GHz, a 3 dB BW exceeding 620 MHz, and an excellent OoB rejection >25 dB, consistent with the acoustic-electric-electromagnetic (EM) multi-physics simulations. Furthermore, through the capacitance-inductance matching network technology, the filter's voltage standing wave ratio (VSWR) is successfully reduced below 2, showing an excellent 50 Ω impedance matching. This study lays a foundation for ultra-high-frequency and ultra-wideband filters for the Wi-Fi 6/6E application.

16.
Behav Sci (Basel) ; 13(9)2023 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-37754015

RESUMEN

Mild cognitive impairment (MCI) is a syndrome that occurs in the preclinical stage of Alzheimer's disease. Early intervention can be effective in preventing Alzheimer's disease, but further research is needed on intervention methods. To identify interventions that are more suitable for Chinese characteristics and to investigate the effects of motor-cognitive intervention on the cognitive functions of older adults with MCI, we screened 103 community-dwelling older adults with MCI aged 65 years and older in Qingdao, Shandong, China; divided them into an intervention group and a control group; and administered a motor-cognitive intervention to the intervention group for 12 weeks. The study used the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) to assess the initial cognitive level of the MCI participants and detect the effects of the intervention. We found that the cognitive abilities of the intervention group were significantly improved at the end of the intervention, as well as at the end of the follow-up, compared with the control group. The results of the current study suggest that the motor-cognitive intervention we used may improve the cognition of older people with MCI in the Chinese community.

17.
Environ Sci Pollut Res Int ; 30(48): 106378-106389, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37728677

RESUMEN

The increase in temperature caused by global climate change has promoted the salinization of wetlands. Inland saline-alkaline wetlands have an environment of over-humidity and shallow water and are hot spots for CH4 emissions. However, there are few reports on the effect of salinity on CH4 emissions in inland saline-alkaline wetlands. This study conducted simulation experiments of increased salinity to investigate the impact of salinity, habitat, and their interactions on CH4 emissions, as well as to examine the response of methanogenic archaea to salinity. Overall, salinity inhibited CH4 emissions. But there were different responses in the three habitat soils. Salinity decreased the relative abundance of methanogenic archaea and changed the community structure. In addition, salinity changed soil pH and dissolved organic carbon (DOC) and ammonium (NH4+) concentrations, which were significantly correlated with methanogenic archaea. Our study showed that salinity changed the soil physicochemical properties and characteristics of the methanogenic archaeal community, affecting CH4 emissions.


Asunto(s)
Archaea , Humedales , Metano , Salinidad , Ecosistema , Suelo/química , Dióxido de Carbono/análisis
18.
Adv Mater ; 35(42): e2305383, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37578079

RESUMEN

The heterogeneous nature, local presence, and dynamic evolution of defects typically govern the ionic and electronic properties of a wide variety of functional materials. While the last 50 years have seen considerable efforts into development of new methods to identify the nature of defects in complex materials, such as the perovskite oxides, very little is known about defect dynamics and their influence on the functionality of a material. Here, the discovery of the intermittent behavior of point defects (oxygen vacancies) in oxide heterostructures employing X-ray photon correlation spectroscopy is reported. Local fluctuations between two ordered phases in strained SrCoOx with different degrees of stability of the oxygen vacancies are observed. Ab-initio-informed phase-field modeling reveals that fluctuations between the competing ordered phases are modulated by the oxygen ion/vacancy interaction energy and epitaxial strain. The results demonstrate how defect dynamics, evidenced by measurement and modeling of their temporal fluctuations, give rise to stochastic properties that now can be fully characterized using coherent X-rays, coupled for the first time to multiscale modeling in functional complex oxide heterostructures. The study and its findings open new avenues for engineering the dynamical response of functional materials used in neuromorphic and electrochemical applications.

19.
Front Chem ; 10: 1062118, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36523747

RESUMEN

Diacylglycerols (DAGs) are important lipid mediators in cellular signaling transduction and metabolism. Imbalanced production or consumption of DAGs has a negative impact on the physiological functions of the body. However, comprehensive monitoring of structurally diverse DAGs remains a daunting task due to the rapid metabolism and ion suppression characteristics in biofluids. These bottlenecks call for developing a method that enables sensitive quantification of DAGs in biological sample. In this work, a straightforward charge derivatization strategy was developed to insert a series of structure analogs charge label, i.e., N, N-dimethylglycine (DMG) and N, N-dimethylalanine (DMA), on the free hydroxyl group of the DAGs. Owing to the existence of tertiary amino groups in charge label, the mass spectrometry ionization response of the derivatized DAGs was significantly increased in comparison with traditional metal ion adducts. After charge derivatization, the specific neutral loss diagnostic ions (DMG, 103 Da and DMA, 117 Da) were captured by mass spectrometry. Then, the DMG/DMA-oriented paired multiple reaction monitoring methods based on the characteristic diagnostic ions of the derivatized DAGs have been developed as sensitive methods for the detection (detection limit = 16 aM) and quantification (quantification limit = 62.5 aM) of DAGs in serum. Moreover, the tagged 1,2-DAGs and 1,3-DAGs sn-isomers have been well separated on the reversed-phase column in combination with ultra-performance liquid chromatography. Finally, metabolic characterizations of the tagged DAGs were further explored in L-Arginine-induced acute pancreatitis mice and resveratrol treated model mice. The results indicated that 1,2-DAGs were increased in the serum of model mice relative to normal controls and resveratrol significantly altered this metabolic abnormality. The currently established DMG/DMA-oriented paired charge derivatization strategy is promising for depicting DAGs changes more accurately in metabolic studies of lipid-related diseases and accurately evaluating drug treatment strategies.

20.
Artículo en Inglés | MEDLINE | ID: mdl-35958909

RESUMEN

Renal fibrosis could lead to chronic kidney disease (CKD) developing into the end-stage with its pathological manifestation is the deposition of extracellular matrix (ECM). Danggui Shaoyao San (DSS) is one of the widely used herbal formulas in ancient China, which has been proven to have efficacy in the treatment of CKD. The experiment employed TGF-ß1 to stimulate the NRK-52E cells to establish a renal fibrosis model. With rapamycin (RAPA) used as the positive control, we detected the expression of fibronectin (FN), caspase-3, and autophagy-related proteins in the NRK-52E cells treated with DSS by Western blot and immunofluorescence assay. In order to further verify autophagy-promoting effects of DSS, we adopted 3-MA to inhibit autophagy. The experiment has found that DSS can lower the protein levels of FN and caspase-3 in the NRK-52E cells induced by TGF-ß1. After TGF-ß1 stimulation, the expression of LC3 II/I and Beclin 1 has decreased, and the protein levels of mTOR and p62 have increased. Consistent with rapamycin, DSS has significantly reduced these effects of TGF-ß1. It has also been found that DSS can increase the expression of LC3 II/I and Beclin 1 proteins and can reduce the level of mTOR in cells treated with 3-MA, suggesting that DSS can promote autophagy. In conclusion, DSS has been proved to reduce the apoptosis and fibrosis of NRK-52E cells induced by TGF-ß1, which may be achieved by promoting autophagy.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA