Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 24
Filtrar
1.
Small ; : e2312136, 2024 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-38482968

RESUMEN

The extraction of ammonia (NH3 ) through electrocatalytic nitrate reduction reaction (NO3 - RR) represents a sustainable avenue in NH3 generation and utilization. However, the catalytic efficiency of the NO3 - RR is hindered by the sluggish kinetics. This study first theoretically found that phosphide-based heterostructure can alter the adsorption structure of intermediates in the nitrate-to-ammonia process, thereby achieving precise regulation of the energy barrier in the rate-determining step. Based on theoretical design, a novel Co-doped Fe2 P@NiP2 heterojunction catalyst is successfully synthesized, which deliver a notable NH3 yield rate of 0.395 mmol h-1  cm-2 at -0.7 V versus RHE, as well as a remarkable ammonia Faraday efficiency of 97.2% at -0.6 V versus RHE. Experimental and theoretical results further confirm that redistributing electrons and shifting the center of the d-band upwards through interfacial doping modulate intermediates adsorption strength and inhibition of hydrogen evolution, leading to excellent performance in NO3 - -to-NH3 . Further integrating the Co-Fe2 P@NiP2 catalyst into a Zn-nitrate battery exhibits a substantial voltage output of 1.49 V and a commendable power density of 13.2 mW cm-2 . The heteroatom-doped heterojunction strategy provides a versatile route for developing advanced catalysts, thereby broadening the horizons of electrocatalytic methodologies for nitrate reduction and ammonia synthesis.

2.
Small ; 19(30): e2302266, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37178389

RESUMEN

Electroreduction of nitrate to ammonia reaction (NO3 - RR) is considered as a promising carbon-free energy technique, which can eliminate nitrate from waste-water also produce value-added ammonia. However, it remains a challenge for achieving satisfied ammonia selectivity and Faraday efficiency (FE) due to the complex multiple-electron reduction process. Herein, a novel Tandem electrocatalyst that Ru dispersed on the porous graphitized C3 N4 (g-C3 N4 ) encapsulated with self-supported Cu nanowires (denoted as Ru@C3 N4 /Cu) for NO3 - RR is presented. As expected, a high ammonia yield of 0.249 mmol h-1  cm-2 at -0.9 V and high FENH3 of 91.3% at -0.8 V versus RHE can be obtained, while achieving excellent nitrate conversion (96.1%) and ammonia selectivity (91.4%) in neutral solution. In addition, density functional theory (DFT) calculations further demonstrate that the superior NO3 - RR performance is mainly resulted from the synergistic effect between the Ru and Cu dual-active sites, which can significantly enhance the adsorption of NO3 - and facilitate hydrogenation, as well as suppress the hydrogen evolution reaction, thus lead to highly improved NO3 - RR performances. This novel design strategy would pave a feasible avenue for the development of advanced NO3 - RR electrocatalysts.

3.
Int J Clin Pract ; 2022: 3356431, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36263235

RESUMEN

Background: Cervical cancer, especially in underdeveloped areas, poses a great threat to human health. In view of this, we stratified the age and social demographic index (SDI) based on the epidemiological development trend and attributable risk of cervical cancer in countries and regions around the world. Methods: According to the data statistics of the global burden of disease database (GBD) in the past 30 years, we adopted the annual percentage change (EAPCs) to evaluate the incidence trend of cervical cancer, that is, incidence rate, mortality, and disability adjusted life expectancy (DALY). Meanwhile, we investigated the potential influence of SDI on cervical cancer's epidemiological trends and relevant risk factors for cervical cancer-related mortality. Results: In terms of incidence rate and mortality, the high SDI areas were significantly lower than those of low SDI areas. The incidence and mortality in women aged 20 to 39 were relatively stable, whereas an upward trend existed in patients aged 40 to 59. The global cervical cancer incidence rate increased from 335642 in 1990 to 565541 in 2019 (an increase of 68.50%, with an average annual growth rate of 2.28%), while the age-standardized incidence rate (ASIR) showed a slight downward trend of 14.91/100000 people (95% uncertainty interval [UI], 13.37-17.55) in 1990 to 13.35/100,000 persons (95% UI, 11.37-15.03) in 2019. The number of annual deaths at a global level increased constantly and there were 184,527 (95% UI, 164,836-218,942) deaths in 1990 and 280,479 (95% UI, 238,864-313,930) deaths in 2019, with an increase of 52.00%(average annual growth rate: 1.73%). The annual age-standardized disability adjusted annual life rate showed a downward trend (decline range: 0.95%, 95% confidence interval [CI], from -1.00% to - 0.89%). In addition, smoking and unsafe sex were the main attributable hazard factors in most GBD regions. Conclusions: In the past three decades, the increase in the global burden of cervical cancer is mainly concentrated in underdeveloped regions (concentrated in low SDI). On the contrary, in countries with high sustainable development index, the burden of cervical cancer tends to be reduced. Alarmingly, ASIR in areas with low SDI is on the rise, which suggests that policy makers should pay attention to the allocation of public health resources and focus on the prevention and treatment of cervical cancer in underdeveloped areas, so as to reduce its incidence rate, mortality, and prognosis.


Asunto(s)
Carga Global de Enfermedades , Neoplasias del Cuello Uterino , Humanos , Femenino , Años de Vida Ajustados por Calidad de Vida , Neoplasias del Cuello Uterino/epidemiología , Salud Global , Factores de Riesgo , Incidencia
4.
Psychol Health Med ; 26(10): 1206-1218, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-32735455

RESUMEN

At present, it is rare for studies to be performed on the impact of self-perceptions of aging on the compliance behaviour of elderly people.The present study explored the relationship between self-perceived of aging level and compliance behavior among asample of elderly Chinese hypertension patients. Participants (N=1129) were recruited from four community health service centres and two township hospitals in Suzhou. Self-perceptions of aging represent an independent risk factor for compliance behaviour in elderly patients with hypertension. Self-perceptions of aging had acute/chronic timeliness (OR=0.793), periodic timeliness (OR=1.439), emotional representation (OR=0.735), positive results (OR=1.322), and identity latitude (OR=0.995). Gender (OR=1.390), age (OR=1.982), residence (OR=7.037), hypertension grade (OR=0.598), sleep (OR=1.709), number of hospital admissions in a year (OR=2.757), number of daily uses of antihypertensive drugs (OR=0.338), and frequency of blood pressure measurement (OR=0.387) were independent factors affecting the compliance behavior of elderly patients with hypertension. The results suggest that self-perceptions of aging can be used as an indirect index to monitor the compliance behaviour of the elderly. In the future medical staff should combine the characteristics of the elderly patients with hypertension, which would help them to establish a positive self-perception of aging, thus improving their compliance behaviour, and the levels of health and literacy.


Asunto(s)
Hipertensión , Anciano , Envejecimiento , Antihipertensivos , Humanos , Hipertensión/tratamiento farmacológico , Hipertensión/epidemiología , Cooperación del Paciente , Autoimagen
5.
Angew Chem Int Ed Engl ; 58(4): 1094-1099, 2019 Jan 21.
Artículo en Inglés | MEDLINE | ID: mdl-30447094

RESUMEN

The uncontrolled growth of Li dendrites upon cycling might result in low coulombic efficiency and severe safety hazards. Herein, a lithiophilic binary lithium-aluminum alloy layer, which was generated through an in situ electrochemical process, was utilized to guide the uniform metallic Li nucleation and growth, free from the formation of dendrites. Moreover, the formed LiAl alloy layer can function as a Li reservoir to compensate the irreversible Li loss, enabling long-term stability. The protected Li electrode shows superior cycling over 1700 h in a Li|Li symmetric cell.

6.
J Am Chem Soc ; 139(25): 8440-8443, 2017 06 28.
Artículo en Inglés | MEDLINE | ID: mdl-28598601

RESUMEN

As promising high-capacity cathode materials for Na-ion batteries, O3-type Na-based metal oxides always suffer from their poor air stability originating from the spontaneous extraction of Na and oxidation of transition metals when exposed to air. Herein, a combined structure modulation is proposed to tackle concurrently the two handicaps via reducing Na layers spacing and simultaneously increasing valence state of transition metals. Guided by density functional theory calculations, we demonstrate such a modulation can be subtly realized through cosubstitution of one kind of heteroatom with comparable electronegativity and another one with substantially different Fermi level, by adjusting the structure of NaNi0.5Mn0.5O2 via Cu/Ti codoping. The as-obtained NaNi0.45Cu0.05Mn0.4Ti0.1O2 exhibits an increase of 20 times in stable air-exposure period and 9 times in capacity retention after 500 cycles, and even retains its structure and capacity after being soaked in water. Such a simple and effective structure modulation reveals a new avenue for high-performance O3-type cathodes and pushes the large-scale industrialization of Na-ion batteries a decisive step forward.

7.
Phys Chem Chem Phys ; 18(14): 9326-33, 2016 Apr 14.
Artículo en Inglés | MEDLINE | ID: mdl-26996438

RESUMEN

Energy storage devices are more important today than any time before in human history due to the increasing demand for clean and sustainable energy. Rechargeable batteries are emerging as the most efficient energy storage technology for a wide range of portable devices, grids and electronic vehicles. Future generations of batteries are required to have high gravimetric and volumetric energy, high power density, low price, long cycle life, high safety and low self-discharge properties. However, it is quite challenging to achieve the above properties simultaneously in state-of-the-art single metal ion batteries (e.g. Li-ion batteries, Na-ion batteries and Mg-ion batteries). In this contribution, hybrid-ion batteries in which various metal ions simultaneously engage to store energy are shown to provide a new perspective towards advanced energy storage: by connecting the respective advantages of different metal ion batteries they have recently attracted widespread attention due to their novel performances. The properties of hybrid-ion batteries are not simply the superposition of the performances of single ion batteries. To enable a distinct description, we only focus on dual-metal-ion batteries in this article, for which the design and the benefits are briefly discussed. We enumerate some new results about dual-metal-ion batteries and demonstrate the mechanism for improving performance based on knowledge from the literature and experiments. Although the search for hybrid-ion batteries is still at an early age, we believe that this strategy would be an excellent choice for breaking the inherent disadvantages of single ion batteries in the near future.

8.
Angew Chem Int Ed Engl ; 54(19): 5757-61, 2015 May 04.
Artículo en Inglés | MEDLINE | ID: mdl-25783632

RESUMEN

Rechargeable magnesium batteries have attracted recent research attention because of abundant raw materials and their relatively low-price and high-safety characteristics. However, the sluggish kinetics of the intercalated Mg(2+) ions in the electrode materials originates from the high polarizing ability of the Mg(2+) ion and hinders its electrochemical properties. Here we report a facile approach to improve the electrochemical energy storage capability of the Li4 Ti5 O12 electrode in a Mg battery system by the synergy between Mg(2+) and Li(+) ions. By tuning the hybrid electrolyte of Mg(2+) and Li(+) ions, both the reversible capacity and the kinetic properties of large Li4 Ti5 O12 nanoparticles attain remarkable improvement.


Asunto(s)
Suministros de Energía Eléctrica , Técnicas Electroquímicas , Litio/química , Magnesio/química , Óxidos/química , Titanio/química , Electrodos
9.
Artículo en Inglés | MEDLINE | ID: mdl-35849722

RESUMEN

Manganese-based layered oxides are one of the most promising cathodes for Na-ion batteries, but the prospect of their practical application is challenged by high sensitivity to ambient air. The stacking structure of materials is critical to the aging mechanism between layered oxides and air, but there remains a lack of systematic study. Herein, comprehensive research on model materials P-type Na0.50MnO2 and O-type Na0.85MnO2 reveals that the O-phase displays a much higher dynamic affinity toward moisture air compared to P-type compounds. For air-exposed O-type material, Na+ ions are extracted from the crystal lattice to form alkaline species at the surface in contact with air, accompanying by the increase of the valence state of transition metals. The series of undesired reactions result in an increase of interfacial resistance and huge capacity loss. Comparatively, the insertion of H2O into the Na layer is the main reaction during air-exposure of P-type material, and the inserted H2O can be extracted by high-temperature treatment. The H2O de/insertion process not only causes no performance degradation but also can enlarge the interlayer distance. With these understandings, we further propose a washing-resintering strategy to recover the performance of aged O-type materials and an aging strategy to build high-performance P-type materials.

10.
Front Pharmacol ; 13: 861183, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35910349

RESUMEN

Objective: Osteoarthritis (OA) is a degenerative joint disease. Excessive nitric oxide (NO) mediates the chondrocyte inflammatory response, apoptosis, and extracellular matrix (ECM) degradation during the occurrence and development of OA. NO in chondrocytes is mainly produced by inducible nitric oxide synthase (iNOS). The aim of this study was to design and synthesize an iNOS dimerization inhibitor and evaluate its effects on chondrocyte inflammation and articular cartilage injury in OA via in vitro and in vivo experiments. Design: The title compound 22o was designed, synthesized, and screened based on a previous study. The effects of different concentrations (5, 10, and 20 µM) of compound 22o on chondrocyte inflammatory response and ECM anabolism or catabolism were evaluated by Western blot and real-time quantitative reverse transcription-polymerase chain reaction using the rat chondrocyte model of IL-1ß-induced OA. Furthermore, different doses (40 and 80 mg/kg) of compound 22o were administered by gavage to a rat OA model induced by anterior cruciate ligament transection (ACLT), and their protective effects on the articular cartilage were evaluated by histopathology and immunohistochemistry. Results: Compound 22o showed effective iNOS inhibitory activity by inhibiting the dimerization of iNOS. It inhibited the IL-1ß-induced expression of cyclooxygenase-2 (COX-2) and matrix metalloproteinase 3 (MMP3) in the chondrocytes, decreased NO production, and significantly increased the expression levels of the ECM anabolic markers, aggrecan (ACAN), and collagen type II (COL2A1). Gavage with compound 22o was found to be effective in the rat OA model induced by ACLT, wherein it regulated the anabolism and catabolism and exerted a protective effect on the articular cartilage. Conclusions: Compound 22o inhibited the inflammatory response and catabolism of the chondrocytes and reduced articular cartilage injury in the rat OA model, indicating its potential as a disease-modifying OA drug.

11.
Acta Biochim Biophys Sin (Shanghai) ; 43(1): 69-78, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-21173058

RESUMEN

MicroRNAs (miRNAs) are non-coding, single-stranded RNAs of approximately 22 nt and constitute a novel class of gene regulators that are found in both plants and animals. Several studies have demonstrated that serum miRNAs could serve as potential biomarkers for the detection of various cancers and other diseases. A few documents regarding the stability of liver cancer-related miRNAs in serum are available. A systemic analysis of the stability of miRNA in serum is quite necessary. The purpose of this study was to evaluate the stability of miRNAs from three different sources, cultured liver cancer Huh-7 cell line, clinical liver cancer, and serum under different experimental conditions, including different temperature, time duration, pH values, RNase A digestion, DNase I digestion, and various freeze-thaw cycles. The qRT-PCR analysis demonstrated that liver cancer-related miRNAs were detectable under each of test conditions, indicating that miRNAs were extremely stable and resistant to destruction and degradation under harsh environmental conditions. However, ribosomal RNA was fragile and easily degraded by demonstrating sharp decrease of relative expression under the non-physiological test conditions. We also established a robust procedure for serum RNA extraction, which is greatly important not only for the miRNA profiling studies but also for the disease prognosis based on abnormal miRNA expression.


Asunto(s)
Neoplasias Hepáticas/genética , MicroARNs/genética , Estabilidad del ARN , Biomarcadores de Tumor/análisis , Línea Celular Tumoral , Humanos , MicroARNs/sangre , MicroARNs/aislamiento & purificación , ARN Neoplásico/aislamiento & purificación , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa
12.
Front Plant Sci ; 12: 791343, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-35069648

RESUMEN

Peatlands are characterized by their large carbon storage capacity and play an essential role in the global carbon cycle. However, the future of the carbon stored in peatland ecosystems under a changing climate remains unclear. In this study, based on the eddy covariance technique, we investigated the net ecosystem CO2 exchange (NEE) and its controlling factors of the Hongyuan peatland, which is a part of the Ruoergai peatland on the eastern Qinghai-Tibet Plateau (QTP). Our results show that the Hongyuan alpine peatland was a CO2 sink with an annual NEE of -226.61 and -185.35 g C m-2 in 2014 and 2015, respectively. While, the non-growing season NEE was 53.35 and 75.08 g C m-2 in 2014 and 2015, suggesting that non-growing seasons carbon emissions should not be neglected. Clear diurnal variation in NEE was observed during the observation period, with the maximum CO2 uptake appearing at 12:30 (Beijing time, UTC+8). The Q10 value of the non-growing season in 2014 and 2015 was significantly higher than that in the growing season, which suggested that the CO2 flux in the non-growing season was more sensitive to warming than that in the growing season. We investigated the multi-scale temporal variations in NEE during the growing season using wavelet analysis. On daily timescales, photosynthetically active radiation was the primary driver of NEE. Seasonal variation in NEE was mainly driven by soil temperature. The amount of precipitation was more responsible for annual variation of NEE. The increasing number of precipitation event was associated with increasing annual carbon uptake. This study highlights the need for continuous eddy covariance measurements and time series analysis approaches to deepen our understanding of the temporal variability in NEE and multi-scale correlation between NEE and environmental factors.

13.
Mol Biol Rep ; 37(3): 1253-9, 2010 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19301144

RESUMEN

Structural differences in oligosaccharides on mammalian zona pellucida 3(ZP3) from different species may determine whether or not spermatozoa being able to bind to ZP. We reported here that by microinjecting the siRNA interference recombinant construct pGenesil-ZP31 encoding a Lagurus zp3 (lzp3) hairpin dsRNA of 21 bp into the inmatured oocytes of Lagurus lagurus, distributed in northern region of Xingjiang, to disturb its fertility. Results of in vitro fertilization after in vitro maturation of the immature oocytes of Lagurus lagurus showed that the fertilization rate of the transgenic oocytes carried pGenesil-ZP31 was decreased greatly (2.82%) compared to the oocytes carried pGenesil-HK (15.71%), suggesting that the transgenic RNAi-mediated silencing of lzp3 in Lagurus lagurus oocytes results in decreased fertilization ability. These results proved that LZP3 of Lagurus lagurus, like other mammalians, is essential for the recognition between oocyte and spermatozoa.


Asunto(s)
Arvicolinae/metabolismo , Fertilización/genética , Glicoproteínas de Membrana/deficiencia , Oocitos/metabolismo , Receptores de Superficie Celular/deficiencia , Animales , China , Cartilla de ADN/genética , Proteínas del Huevo/genética , Proteínas del Huevo/metabolismo , Fertilización In Vitro , Inmunohistoquímica , Secuencias Invertidas Repetidas/genética , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Microinyecciones , Interferencia de ARN , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Glicoproteínas de la Zona Pelúcida
14.
ACS Appl Mater Interfaces ; 11(25): 22067-22073, 2019 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-31013426

RESUMEN

As high capacity cathodes, O3-type Na-based oxides always suffer from a series of monoclinic transitions upon sodiation/desodiation, mainly caused by Na+/vacancy ordering and Jahn-Teller (J-T) distortion, leading to rapid structural degradation and serious performance fading. Herein, a simple modulation strategy is proposed to address this issue based on refrainment of electron localization in expectation to alleviate the charge ordering and change of electronic structure, which always lead to Na+/vacancy ordering and J-T distortion, respectively. According to density functional theory calculations, Fe3+ with slightly larger radius is introduced into NaNi0.5Mn0.5O2 with the intention of enlarging transition metal layers and facilitating electronic delocalization. The obtained NaFe0.3Ni0.35Mn0.35O2 exhibits a reversible phase transition of O3hex-P3hex without any monoclinic transitions in striking contrast with the complicated phase transitions (O3hex-O'3mon-P3hex-P'3mon-P3'hex) of NaNi0.5Mn0.5O2, thus excellently improving the capacity retention with a high rate kinetic. In addition, the strategy is also effective to enhance the air stability, proved by direct observation of atomic-scale ABF-STEM for the first time.

15.
Yao Xue Xue Bao ; 43(2): 150-6, 2008 Feb.
Artículo en Zh | MEDLINE | ID: mdl-18507341

RESUMEN

This study is to investigate the protective effect of urantide against myocardial ischemia injury in mice and its mechanism. The ischemic model was made by using subcutaneous injection of isoproterenol (Iso) in mice, the change of ST segment of electrocardiogram (ECG) was observed, and the activitise of lactate dehydrogenase (LDH) and nitric oxide synthetase (NOS), the contents of malonaldehyde (MDA) and nitric oxide (NO) in serum were measured. The histopathological changes of myocardium were observed by using HE staining. The anoxia/reoxygenation (A/R) model of myocardial cells on neonatal Sprague-Dawley rats was established. Methyl thiazolyl tetrazolium (MTT) assay and confocal microscopy were respectively used to measure the viability and intracellular Ca2+ concentration in myocardial cells exposed to A/R. LDH activity and cTnI content in the cell culture medium were assayed for the evaluation of myocardial cells injury. The results revealed that urantide in the range of 3 - 30 microg kg(-1) iv markedly inhibited Iso-induced raise of the ST segment of ECG; 10 and 30 microg kg(-1) significantly reduced the increases of MDA content and LDH activity in mice serum, remarkably raised the activity of NOS and the content of NO. Urantide (10 and 30 microg kg(-1)) also significantly ameliorated myocardial ischemic injury. On the A/R model of myocardial cells, urantide (1 x 10(-6) - 1 x 10(-9) mol L(-1)) could evidently inhibit the increases of cTnI content, reduce the rise of intracellular Ca2+ concentration. Urantide (1 x 10(-6) - 1 x 10(-7)) mol L(-1) increased the viability of myocardial cells injured by A/R and cut down LDH activity in the cell culture medium. Therefore urantide has significant protective effect against myocardial ischemia or A/R injury via the inhibition of Ca2+ overload and the augmentation of NO synthesis.


Asunto(s)
Calcio/metabolismo , Cardiotónicos/farmacología , Isquemia Miocárdica , Óxido Nítrico Sintasa/sangre , Fragmentos de Péptidos/farmacología , Urotensinas/farmacología , Animales , Células Cultivadas , Electrocardiografía , Femenino , Isoproterenol , L-Lactato Deshidrogenasa/sangre , Masculino , Malondialdehído/sangre , Ratones , Isquemia Miocárdica/sangre , Isquemia Miocárdica/inducido químicamente , Isquemia Miocárdica/patología , Miocardio/patología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Óxido Nítrico/sangre , Ratas , Ratas Sprague-Dawley , Troponina I/metabolismo
16.
Sci Adv ; 4(3): eaar6018, 2018 03.
Artículo en Inglés | MEDLINE | ID: mdl-29536049

RESUMEN

As one of the most fascinating cathode candidates for Na-ion batteries (NIBs), P2-type Na layered oxides usually exhibit various single-phase domains accompanied by different Na+/vacancy-ordered superstructures, depending on the Na concentration when explored in a limited electrochemical window. Therefore, their Na+ kinetics and cycling stability at high rates are subjected to these superstructures, incurring obvious voltage plateaus in the electrochemical profiles and insufficient battery performance as cathode materials for NIBs. We show that this problem can be effectively diminished by reasonable structure modulation to construct a completely disordered arrangement of Na-vacancy within Na layers. The combined analysis of scanning transmission electron microscopy, ex situ x-ray absorption spectroscopy, and operando x-ray diffraction experiments, coupled with density functional theory calculations, reveals that Na+/vacancy disordering between the transition metal oxide slabs ensures both fast Na mobility (10-10 to 10-9 cm2 s-1) and a low Na diffusion barrier (170 meV) in P2-type compounds. As a consequence, the designed P2-Na2/3Ni1/3Mn1/3Ti1/3O2 displays extra-long cycle life (83.9% capacity retention after 500 cycles at 1 C) and unprecedented rate capability (77.5% of the initial capacity at a high rate of 20 C). These findings open up a new route to precisely design high-rate cathode materials for rechargeable NIBs.

17.
Chem Commun (Camb) ; 53(12): 1957-1960, 2017 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-28119964

RESUMEN

A novel P2-type Na2/3Ni1/6Mg1/6Ti2/3O2 material is explored as an anode for sodium-ion batteries (SIBs) for the first time. It delivers a reversible capacity of 92 mA h g-1 with a safe average storage voltage of approximately 0.7 V in a sodium half-cell, and exhibits good cycle stability (ca. 87.4% capacity retention for 100 cycles) at a cut-off voltage of 0.2-2.5 V, indicating its superiority as a promising candidate anode material for SIBs.

18.
Adv Mater ; 29(19)2017 May.
Artículo en Inglés | MEDLINE | ID: mdl-28295700

RESUMEN

Sodium-ion batteries (SIBs) have been considered as potential candidates for stationary energy storage because of the low cost and wide availability of Na sources. O3-type layered oxides have been considered as one of the most promising cathodes for SIBs. However, they commonly show inevitable complicated phase transitions and sluggish kinetics, incurring rapid capacity decline and poor rate capability. Here, a series of sodium-sufficient O3-type NaNi0.5 Mn0.5-x Ti x O2 (0 ≤ x ≤ 0.5) cathodes for SIBs is reported and the mechanisms behind their excellent electrochemical performance are studied in comparison to those of their respective end-members. The combined analysis of in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, and scanning transmission electron microscopy for NaNi0.5 Mn0.2 Ti0.3 O2 reveals that the O3-type phase transforms reversibly into a P3-type phase upon Na+ deintercalation/intercalation. The substitution of Ti for Mn enlarges interslab distance and could restrain the unfavorable and irreversible multiphase transformation in the high voltage regions that is usually observed in O3-type NaNi0.5 Mn0.5 O2 , resulting in improved Na cell performance. This integration of macroscale and atomicscale engineering strategy might open up the modulation of the chemical and physical properties in layered oxides and grasp new insight into the optimal design of high-performance cathode materials for SIBs.

19.
Sci Total Environ ; 607-608: 253-261, 2017 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-28692895

RESUMEN

Volatile Organic Compounds (VOCs) source profiles of on-road vehicles were widely studied as their critical roles in VOCs source apportionment and abatement measures in megacities. Studies of VOCs source profiles from on-road motor vehicles from 2001 to 2016 were summarized in this study, with a focus on the comparisons among different studies and the potential impact of different factors. Generally, non-methane hydrocarbons dominated the source profile of on-road vehicle emissions. Carbonyls, potential important components of vehicle emission, were seldom considered in VOCs emissions of vehicles in the past and should be paid more attention to in further study. VOCs source profiles showed some variations among different studies, and 6 factors were extracted and studied due to their impact to VOCs source profile of on-road vehicles. Vehicle types, being dependent on engine types, and fuel types were two dominant factors impacting VOCs sources profiles of vehicles. In comparison, impacts of ignitions, driving conditions and accumulated mileage were mainly due to their influence on the combustion efficiency. An opening and interactive database of VOCs from vehicle emissions was critically essential in future, and mechanisms of sharing and inputting relative research results should be formed to encourage researchers join the database establishment. Correspondingly, detailed quality assurance and quality control procedures were also very important, which included the information of test vehicles and test methods as detailed as possible. Based on the community above, a better uncertainty analysis could be carried out for the VOCs emissions profiles, which was critically important to understand the VOCs emission characteristics of the vehicle emissions.

20.
Adv Mater ; 28(33): 7243-8, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27305570

RESUMEN

A subzero-temperature cathode material is obtained by nucleating cubic prussian blue crystals at inhomogeneities in carbon nanotubes. Due to fast ionic/electronic transport kinetics even at -25 °C, the cathode shows an outstanding low-temperature performance in terms of specific energy, high-rate capability, and cycle life, providing a practical sodium-ion battery powering an electric vehicle in frigid regions.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA