RESUMEN
Livestock and poultry products are an essential human food source. However, the rapid development of the livestock sector (LS) has caused it to become a significant source of greenhouse gas (GHG) emissions. Consequently, investigating the spatio-temporal characteristics and evolution of GHG emissions is crucial to facilitate the green development of the LS and achieve "peak carbon and carbon neutrality". This study combined life cycle assessment (LCA) with the IPCC Tier II method to construct a novel GHG emissions inventory. The GHG emissions of 31 provinces in China from 2000 to 2021 were calculated, and their spatio-temporal characteristics were revealed. Then, the stochastic impacts by regression on population, affluence, and technology (STIRPAT) model was used to identify the main driving factors of GHG emissions in six regions of China and explore the emission reduction potential. The results showed that GHG emissions increased and then decreased from 2000 to 2021, following a gradual and steady trend. The peak of 628.55 Mt CO2-eq was reached in 2006. The main GHG-producing segments were enteric fermentation, slaughtering and processing, and manure management, accounting for 45.39 %, 26.34 %, and 23.08 % of total GHG emissions, respectively. Overall, the center of gravity of GHG emissions in China migrated northward, with spatial aggregation observed since 2016. The high emission intensity regions were mainly located west of the "Hu Huanyong line". Economic efficiency and emissions intensity were the main drivers of GHG emissions. Under the baseline scenario, GHG emissions are not projected to peak until 2050. Therefore, urgent action is needed to promote the low-carbon green development of the LS in China. The results can serve as scientific references for the macro-prevention and control of GHG emissions, aiding strategic decision-making. Additionally, they can provide new ideas for GHG accounting in China and other countries around the world.
Asunto(s)
Contaminantes Atmosféricos , Monitoreo del Ambiente , Gases de Efecto Invernadero , Ganado , Gases de Efecto Invernadero/análisis , China , Animales , Contaminantes Atmosféricos/análisis , Crianza de Animales Domésticos/métodos , Contaminación del Aire/estadística & datos numéricosRESUMEN
Ecosystem services (ESs) and their changes are complex processes driven by multiple factors. Understanding the trade-off and synergy between ESs and their driving factors is essential for achieving effective management of ESs and human well-being. Taking the Yangtze River Economic Belt as the research area, this study analyzed the temporal and spatial variation characteristics of four ESs including water yield, soil conservation, carbon sequestration, and food supply from 2000 to 2020. Correlation analysis and geographically weighted regression were used to identify and quantify the trade-off and synergy between ESs. On this basis, the partial least squares structural equation model was used to explore the impact of natural and human activities on ESs, and then the driving mechanism of ESs relationship change was analyzed via GeoDetector. The results showed that:â During the 20 years, the average annual carbon sequestration increased from 946.14 t·km-2 to 1 202.73 t·km-2, and the average food supply increased from 32.73×104 Yuan·km-2 to 127.22×104 Yuan·km-2. Water yield and soil conservation increased to a lesser degree. â¡ On the whole, carbon sequestration and soil conservation and food supply and water yield showed synergy, and other ESs were trade-offs. The relationship between ESs varied in different regions. ⢠Terrain and climate were important driving factors for ESs and the trade-off and synergy of multiple ESs. Among them, structural equation model results showed that climate had a positive impact on water yield (S=0.73), and terrain had a negative impact on food supply (S=-0.57). GeoDetector results revealed that the main driving factors affecting the spatial relationship between carbon sequestration and water yield were elevation (q=0.38) and precipitation (q=0.19). The results of this study can provide a scientific reference for the sustainable management of ESs in the Yangtze River Economic Belt and the realization of the coordinated development of ecological environment protection and social economy in the region.
RESUMEN
BACKGROUND: Anthocyanins have anti-inflammatory and antioxidant properties. Several studies have demonstrated that anthocyanins are associated with many chronic diseases, but few studies have focused on the relationship between anthocyanins and chronic obstructive pulmonary disease (COPD). OBJECTIVES: This survey aimed to explore the relationship between dietary anthocyanin intake and COPD in US adults over the age of 40. METHODS: A cross-sectional study from the National Health and Nutrition Examination Survey (NHANES) 2017-2018 was conducted. We used univariate and multivariate logistic regression and restricted cubic spline (RCS) to analyze the relationship between dietary anthocyanins and COPD. Subgroup and interaction analyses were adopted to assess whether there were differences in the relationship between dietary anthocyanin intake and COPD in different groups. RESULTS: A total of 2862 participants aged ≥ 40 years were analyzed, of whom 213 were diagnosed with COPD. The highest tertile of dietary anthocyanin intake was negatively correlated with COPD compared to the lowest after adjusting potential confounders (Model 1, OR = 0.414; 95% CI: (0.245, 0.699), P-trend = 0.002; Model 2, OR = 0.363; 95% CI: (0.210, 0.627), P-trend = 0.002; Model 3, OR = 0.614; 95% CI: (0.383, 0.985), P-trend = 0.040). The RCS curve showed a significant inverse linear relationship between dietary anthocyanin intake and COPD (P non-linear = 0.734). In subgroup analyses, the negative correlation between dietary anthocyanin intake and COPD existed across different subgroups. CONCLUSION: Our study indicated that higher dietary anthocyanins are a protective factor against the presence of COPD in the US aged over 40.
Asunto(s)
Antocianinas , Encuestas Nutricionales , Enfermedad Pulmonar Obstructiva Crónica , Humanos , Enfermedad Pulmonar Obstructiva Crónica/epidemiología , Antocianinas/administración & dosificación , Masculino , Femenino , Estudios Transversales , Persona de Mediana Edad , Estados Unidos/epidemiología , Adulto , Anciano , Dieta/estadística & datos numéricos , Dieta/métodos , Bases de Datos Factuales , Factores de RiesgoRESUMEN
BACKGROUND: Several studies have shown that dietary isoflavones are negatively correlated with total cholesterol and low-density lipoprotein cholesterol. However, few studies have investigated the link between dietary isoflavones and remnant cholesterol (RC). OBJECTIVES: We used the National Health and Nutrition Examination Survey (NHANES) database to explore the association between dietary isoflavone intake and RC. METHODS: A cross-sectional study was conducted with 4731 participants aged ≥ 20 years from the 2007-2008, 2009-2010, and 2017-2018 NHANES databases. We adopted univariate and multiple linear regression analysis and restricted cubic spline (RCS) to assess the relationship between dietary isoflavone intake and RC. Moreover, we conducted stratified and interaction analyses to ensure the stability of the results and identify specific populations. RESULTS: The weighted multifactor linear regression model showed a negative correlation between dietary isoflavone intake and remnant cholesterol (Model 2, ß = -0.049, 95% CI: (-0.096, -0.002), P = 0.040). The RCS analysis indicated that there was an L-shaped negative correlation between dietary isoflavone intake and RC (P-value for non-linearity was 0.0464). Stratified analyses showed the inverse relationship between dietary isoflavone intake and RC persisted in most subgroups and there was no interaction except for the recreational activity group. CONCLUSIONS: Our study found a non-linear and negative association between dietary isoflavone intake and RC in US adults, so we hypothesized that consuming an isoflavone-rich diet may help reduce blood RC and further reduce the risk of cardiovascular disease.
Asunto(s)
Colesterol , Isoflavonas , Encuestas Nutricionales , Humanos , Isoflavonas/administración & dosificación , Estudios Transversales , Masculino , Femenino , Encuestas Nutricionales/métodos , Colesterol/sangre , Adulto , Persona de Mediana Edad , Estados Unidos/epidemiología , Dieta/estadística & datos numéricos , Dieta/métodos , AncianoRESUMEN
OBJECTIVE: Smoking was a major risk factor for chronic obstructive pulmonary disease (COPD). This study plan to explore the mechanism of Polyphyllin B in lung injury induced by cigarette smoke (CSE) in COPD. METHODS: Network pharmacology and molecular docking were applied to analyze the potential binding targets for Polyphyllin B and COPD. Commercial unfiltered CSE and LPS were used to construct BEAS-2B cell injury in vitro and COPD mouse models in vivo, respectively, which were treated with Polyphyllin B or fecal microbiota transplantation (FMT). CCK8, LDH and calcein-AM were used to detect the cell proliferation, LDH level and labile iron pool. Lung histopathology, Fe3+ deposition and mitochondrial morphology were observed by hematoxylin-eosin, Prussian blue staining and transmission electron microscope, respectively. ELISA was used to measure inflammation and oxidative stress levels in cells and lung tissues. Immunohistochemistry and immunofluorescence were applied to analyze the 4-HNE, LC3 and Ferritin expression. RT-qPCR was used to detect the expression of FcRn, pIgR, STAT3 and NCOA4. Western blot was used to detect the expression of Ferritin, p-STAT3/STAT3, NCOA4, GPX4, TLR2, TLR4 and P65 proteins. 16S rRNA gene sequencing was applied to detect the gut microbiota. RESULTS: Polyphyllin B had a good binding affinity with STAT3 protein, which as a target gene in COPD. Polyphyllin B inhibited CS-induced oxidative stress, inflammation, mitochondrial damage, and ferritinophagy in COPD mice. 16S rRNA sequencing and FMT confirmed that Akkermansia and Escherichia_Shigella might be the potential microbiota for Polyphyllin B and FMT to improve CSE and LPS-induced COPD, which were exhausted by the antibiotics in C + L and C + L + P mice. CSE and LPS induced the decrease of cell viability and the ferritin and LC3 expression, and the increase of NCOA4 and p-STAT3 expression in BEAS-2B cells, which were inhibited by Polyphyllin B. Polyphyllin B promoted ferritin and LC3II/I expression, and inhibited p-STAT3 and NCOA4 expression in CSE + LPS-induced BEAS-2B cells. CONCLUSION: Polyphyllin B improved gut microbiota disorder and inhibited STAT3/NCOA4 pathway to ameliorate lung tissue injury in CSE and LPS-induced mice.
Asunto(s)
Fumar Cigarrillos , Microbioma Gastrointestinal , Lesión Pulmonar , Enfermedad Pulmonar Obstructiva Crónica , Animales , Ratones , Línea Celular , Fumar Cigarrillos/efectos adversos , Ferritinas/metabolismo , Inflamación/patología , Lipopolisacáridos/efectos adversos , Pulmón , Lesión Pulmonar/complicaciones , Lesión Pulmonar/metabolismo , Lesión Pulmonar/patología , Simulación del Acoplamiento Molecular , Enfermedad Pulmonar Obstructiva Crónica/terapia , Enfermedad Pulmonar Obstructiva Crónica/tratamiento farmacológico , ARN Ribosómico 16S , Factor de Transcripción STAT3/genética , Factor de Transcripción STAT3/metabolismoRESUMEN
Lithium (Li) metal batteries are highly sought after for their exceptional energy density. However, their practical implementation is impeded by the formation of dendrites and significant volume fluctuations in Li, which stem from the uneven distribution of Li-ions and uncontrolled deposition of Li on the current collector. Here, an amino-functionalized reduced graphene oxide covered with polyacrylonitrile (PrGN) film with an electric field gradient structure is prepared to deal with such difficulties. This novel current collector serves to stabilize Li-metal anodes by regulating Li-ion flux through vertically aligned channels formed by porous polyacrylonitrile (PAN). Moreover, the amino-functionalized reduced graphene oxide (rGN) acts as a three-dimensional (3D) host, reducing nucleation overpotential and accommodating volume expansion during cycling. The combination of the insulating PAN and conducting rGN creates an electric field gradient that promotes a bottom-up mode of Li electrodeposition and safeguards the anode from interfacial parasitic reactions. Consequently, the electrodes exhibit exceptional cycle life with stable voltage profiles and minimal hysteresis under high current densities and large areal capacities.
RESUMEN
IMPORTANCE: Autophagy is a conserved degradation process that maintains cellular homeostasis and regulates native and adaptive immunity. Viruses have evolved diverse strategies to inhibit or activate autophagy for their benefit. The paper reveals that CSFV NS5A mediates the dissociation of PP2A from Beclin 1 and the association of PP2A with DAPK3 by interaction with PPP2R1A and DAPK3, PP2A dephosphorylates DAPK3 to activate its protein kinase activity, and activated DAPK3 phosphorylates Beclin 1 to trigger autophagy, indicating that NS5A activates autophagy via the PP2A-DAPK3-Beclin 1 axis. These data highlight a novel mechanism by which CSFV activates autophagy to favor its replication, thereby contributing to the development of antiviral strategies.
Asunto(s)
Autofagia , Virus de la Fiebre Porcina Clásica , Peste Porcina Clásica , Proteínas no Estructurales Virales , Animales , Beclina-1/metabolismo , Peste Porcina Clásica/inmunología , Peste Porcina Clásica/virología , Virus de la Fiebre Porcina Clásica/fisiología , Porcinos , Replicación Viral , Proteínas no Estructurales Virales/metabolismoRESUMEN
PURPOSE: Ultrasound imaging is the preferred method for the early diagnosis of endometrial diseases because of its non-invasive nature, low cost, and real-time imaging features. However, the accurate evaluation of ultrasound images relies heavily on the experience of radiologist. Therefore, a stable and objective computer-aided diagnostic model is crucial to assist radiologists in diagnosing endometrial lesions. METHODS: Transvaginal ultrasound images were collected from multiple hospitals in Quzhou city, Zhejiang province. The dataset comprised 1875 images from 734 patients, including cases of endometrial polyps, hyperplasia, and cancer. Here, we proposed a based self-supervised endometrial disease classification model (BSEM) that learns a joint unified task (raw and self-supervised tasks) and applies self-distillation techniques and ensemble strategies to aid doctors in diagnosing endometrial diseases. RESULTS: The performance of BSEM was evaluated using fivefold cross-validation. The experimental results indicated that the BSEM model achieved satisfactory performance across indicators, with scores of 75.1%, 87.3%, 76.5%, 73.4%, and 74.1% for accuracy, area under the curve, precision, recall, and F1 score, respectively. Furthermore, compared to the baseline models ResNet, DenseNet, VGGNet, ConvNeXt, VIT, and CMT, the BSEM model enhanced accuracy, area under the curve, precision, recall, and F1 score in 3.3-7.9%, 3.2-7.3%, 3.9-8.5%, 3.1-8.5%, and 3.3-9.0%, respectively. CONCLUSION: The BSEM model is an auxiliary diagnostic tool for the early detection of endometrial diseases revealed by ultrasound and helps radiologists to be accurate and efficient while screening for precancerous endometrial lesions.
Asunto(s)
Médicos , Lesiones Precancerosas , Enfermedades Uterinas , Humanos , Femenino , Simulación por Computador , Hospitales , Hiperplasia , Lesiones Precancerosas/diagnóstico por imagenRESUMEN
Understanding the response mechanism of ecosystem services (ES) to landscape patterns is important in regional landscape planning and sustainable development. In this study, the landscape index and InVEST model were used to quantitatively analyze the spatio-temporal evolution of landscape patterns and ES in the Ganjiang River Basin of China from 1990 to 2020. Furthermore, the bivariate Moran's I method and spatial error model were used to test the spatial correlation between landscape index and ES. The results showed that (1) cropland decreased and construction land increased, and the overall landscape tended to be fragmented, the patch shape complicated, and landscape diversity increased from 1990 to 2020. Water conservation (WC) and soil conservation (SC) capacity increased by 10.56 mm and 16.24 t hm-2 a-1, respectively, whereas carbon storage (CS) decreased by 1.22 t hm-2 a-1. (2) The responses of different typical ES to landscape patterns were different in the landscape index and response degree. Typical ES negatively responded to Shannon's diversity index and patch density. WC was sensitive to the Splitting Index, whereas SC and CS were more responsive to the average patch area. (3) The overall purpose of territorial spatial planning within a basin should be to reduce the fragmentation and heterogeneity of the landscape. According to four local aggregation patterns of landscape index and ES, corresponding measures can be taken according to local conditions in different regions. These results can provide a quantitative basis for landscape management and ecological construction in the Ganjiang River Basin and scientific guidance for the Yangtze River conservation strategy.
Asunto(s)
Ecosistema , Ríos , Conservación de los Recursos Naturales , ChinaRESUMEN
The NS5A non-structural protein of classical swine fever virus (CSFV) is a multifunctional protein involved in viral genomic replication, protein translation, assembly of infectious virus particles, and regulation of cellular signaling pathways. Previous report showed that NS5A inhibited nuclear factor kappa B (NF-κB) signaling induced by poly(I:C); however, the mechanism involved has not been elucidated. Here, we reported that NS5A directly interacted with NF-κB essential modulator (NEMO), a regulatory subunit of the IκB kinase (IKK) complex, to inhibit the NF-κB signaling pathway. Further investigations showed that the zinc finger domain of NEMO and the aa 126-250 segment of NS5A are essential for the interaction between NEMO and NS5A. Mechanistic analysis revealed that NS5A mediated the proteasomal degradation of NEMO. Ubiquitination assay showed that NS5A induced the K27-linked but not the K48-linked polyubiquitination of NEMO for proteasomal degradation. In addition, NS5A blocked the K63-linked polyubiquitination of NEMO, thus inhibiting IKK phosphorylation, IκBα degradation, and NF-κB activation. These findings revealed a novel mechanism by which CSFV inhibits host innate immunity, which might guide the drug design against CSFV in the future.
Asunto(s)
Virus de la Fiebre Porcina Clásica , FN-kappa B , Animales , Porcinos , FN-kappa B/metabolismo , Virus de la Fiebre Porcina Clásica/metabolismo , Transducción de Señal , Quinasa I-kappa B/genética , Quinasa I-kappa B/metabolismo , Inmunidad InnataRESUMEN
BACKGROUND: Deep learning has been successfully applied to low-dose CT (LDCT) denoising. But the training of the model is very dependent on an appropriate loss function. Existing denoising models often use per-pixel loss, including mean abs error (MAE) and mean square error (MSE). This ignores the difference in denoising difficulty between different regions of the CT images and leads to the loss of large texture information in the generated image. PURPOSE: In this paper, we propose a new hybrid loss function that adapts to the noise in different regions of CT images to balance the denoising difficulty and preserve texture details, thus acquiring CT images with high-quality diagnostic value using LDCT images, providing strong support for condition diagnosis. METHODS: We propose a hybrid loss function consisting of weighted patch loss (WPLoss) and high-frequency information loss (HFLoss). To enhance the model's denoising ability of the local areas which are difficult to denoise, we improve the MAE to obtain WPLoss. After the generated image and the target image are divided into several patches, the loss weight of each patch is adaptively and dynamically adjusted according to its loss ratio. In addition, considering that texture details are contained in the high-frequency information of the image, we use HFLoss to calculate the difference between CT images in the high-frequency information part. RESULTS: Our hybrid loss function improves the denoising performance of several models in the experiment, and obtains a higher peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM). Moreover, through visual inspection of the generated results of the comparison experiment, the proposed hybrid function can effectively suppress noise and retain image details. CONCLUSIONS: We propose a hybrid loss function for LDCT image denoising, which has good interpretation properties and can improve the denoising performance of existing models. And the validation results of multiple models using different datasets show that it has good generalization ability. By using this loss function, high-quality CT images with low radiation are achieved, which can avoid the hazards caused by radiation and ensure the disease diagnosis for patients.
Asunto(s)
Procesamiento de Imagen Asistido por Computador , Tomografía Computarizada por Rayos X , Humanos , Tomografía Computarizada por Rayos X/métodos , Relación Señal-Ruido , Procesamiento de Imagen Asistido por Computador/métodos , AlgoritmosRESUMEN
Bismuth (Bi) has emerged as a promising candidate for sodium-ion battery anodes because of its unique layered crystal structure, superior volumetric capacity, and high theoretical gravimetric capacity. However, the large volume expansion and severe aggregation of Bi during the alloying/dealloying reactions are extremely detrimental to cycling stability, which seriously hinders its practical application. To overcome these issues, we propose an effective synthesis of composite materials, encapsulating Bi nanoparticles in N,S co-doped carbon nanoribbons and composites with carbon nanotubes (N,S-C@Bi/CNT), using Bi2S3 nanobelts as templates. The uniform distribution of Bi nanoparticles and the structure of carbon nanoribbons can reduce the diffusion path of ions/electrons, efficiently buffer the large volume change and prevent Bi from aggregating during cycles. As expected, the N,S-C@Bi/CNT electrode shows superior sodium storage performance in half cells, including a high specific capacity (345.3 mA h g-1 at 1.0 A g-1), long cycling stability (1000 cycles), and superior rate capability (336.0 mA h g-1 at 10.0 A g-1).
RESUMEN
In this study, a highly efficient phosphate adsorbent (MBC/Mg-La) based on magnetic biochar was successfully synthesized through Mg-La modification. The phosphate adsorption capacity of biochar was significantly enhanced after Mg-La modification. The adsorbent exhibited an excellent phosphate adsorption performance, particularly for treating low-concentration phosphate wastewater. Within a wide pH range, the adsorbent maintained a stable phosphate adsorption capacity. Furthermore, it showed a high adsorption selectivity for phosphate. Therefore, given the excellent phosphate adsorption performance, the adsorbent could effectively inhibit algae growth by removing phosphate from water. Furthermore, the adsorbent after phosphate adsorption can be easily recycled through magnetic separation, which can serve as a phosphorus fertilizer to promote the growth of Lolium perenne L.
Asunto(s)
Herbicidas , Contaminantes Químicos del Agua , Fosfatos , Adsorción , Fertilizantes , Fenómenos Magnéticos , CinéticaRESUMEN
Metal-Organic frameworks (MOFs) are increasingly being investigated for the synthesis of carbon-supported metal-based ultrafine nanoparticles (UNPs). However, the collapse of the carbon framework and aggregation of metal particles in the pyrolysis process have severely hindered their stability and applications. Here, we report the synchronous nucleation pseudopyrolysis of MOFs to confine Fe/FeOx UNPs in intact porous carbon nanorods (IPCNs), revealed by in situ transmission electron microscopy experiments and ex situ structure analysis. The pseudopyrolysis mechanism enables strong physical and chemical confinement effects between UNPs and carbon by moderate thermal kinetics and abundant oxygen defects. Further, this strong confinement is greatly beneficial for subsequent chemical transformations to obtain different Fe-based UNPs and excellent electrochemical performance. As a proof of concept, the as-prepared FeSe UNPs in IPCNs show superior lithium storage performance with an ultrahigh and stable capacity of 815.1 mAh g-1 at 0.1 A g -1 and 379.7 mAh g-1 at 5 A g-1 for 1000 cycles.
RESUMEN
@#Abstract:Objective To prepare human monoclonal antibody against spike protein(S protein)of severe acute respiratory syndrome coronavirus 2(SARS⁃CoV⁃2)by using single B cell,and determine its neutralizing activity. Methods Venous blood with high antibody level was collected from people immunized with inactivated SARS⁃CoV⁃2 vaccine(Vero cells) twice,of which peripheral blood mononuclear cells(PBMCs)were isolated by lymphocyte stratified fluid and used to isolate single B cell expressing S protein antibody by magnetic beads coupled with S1 protein. Variable region genes of IgG heavy chain and light chain were amplified by nested PCR after reverse transcription of single B cell,which were connected with CMV promoter,IgG leader sequence,IgG constant region and polyA sequence by overlapping PCR to construct antibody linear expression cassette. Linear expression cassette of the heavy chain and light chain from the same B cell was transfected to HEK293T cells to express human monoclonal antibody of SARS⁃CoV⁃2 S protein. Immunoreactivity was detected by immuno⁃ fluorescence while neutralizing activity by pseudovirus neutralization test. Results A total of 26 monoclonal antibodies against SARS⁃CoV⁃2 S protein were expressed,which showed heavy chain and light chain protein bands of IgG antibody at
RESUMEN
The poor conductivity, inert charge transmission efficiency, and irreversible Na+ trapping of Na2 Ti3 O7 result in retardant electrons/ions transportation and deficient sodium-ion storage efficiency, leading to sluggish reaction kinetics. To address these issues, an urchin-like Ti2 CTx /Na2 Ti3 O7 (Ti2 C/NTO) heterostructure sphere consisting of Ti2 C/NTO heterostructure nanobelts array is developed via a facile one-step in situ hydrothermal strategy. The Ti2 C/NTO heterostructure can obviously decrease Na+ diffusion barriers and increase electronic conductivity to improve reaction kinetics due to the built-in electric field effect and high-quantity interface region. In addition, the urchin-like vertically aligned nanobelts can reduce the diffusion distance of electrons and ions, provide favored electrolyte infiltration, adapt large volume expansion, and mitigate the aggregation to maintain structural stability during cycles, further enhancing the reaction kinetics. Furthermore, the Ti2 C/NTO heterostructure can effectively suppress many unwanted side reactions between reactive surface sites of NTO and electrolyte as well as irreversible trapping of Na+ . As a result, systematic electrochemical investigations demonstrate that the Ti2 C/NTO heterostructure as an anode material for record sodium-ion storage delivers the highest reversible capacity, the best cycling stability with 0.0065% decay rate for 4500 cycles at 2.0 A g-1 , and excellent rate capability of 172.1 mAh g-1 at 10.0 A g-1 .
RESUMEN
Catalysis has been regarded as an effective strategy to mitigate sluggish reaction kinetics and serious shuttle effect of Li-S batteries. Herein, a spherical structure consists of ultrathin layered Ti3C2Tx-TiN heterostructures (MX-TiN) through in-situ nitridation method is reported. Through controllable nitridation, highly conductive TiN layer grew on the surface and close coupled with interior MXene to form unique 2D heterostructures. The ultrathin heterostructure with only several nanometers in thickness enables outstanding ability to shorten electrons diffusion distance during electrochemical reactions and enlarge active surface with abundant adsorptive and catalytic sites. Moreover, the (001) surface of TiN is dominated by metallic Ti-3d states, which ensures fast transmitting electrons from high conductive MX-TiN matrix and thus guarantees efficient catalytic performance. Calculations and experiments demonstrate that polysulfides are strongly immobilized on MX-TiN, meanwhile the bidirectional reaction kinetics are catalytically enhanced by reducing the conversion barrier between liquid LiPSs and solid Li2S2/Li2S. As a result, the S/MX-TiN cathode achieves excellent long-term cyclability with extremely low-capacity fading rate of 0.022% over 1000 cycles and remarkable areal capacity of 8.27 mAh cm-2 at high sulfur loading and lean electrolytes.
RESUMEN
With the rapid advancement of urbanization and industrialization, the contradiction between the social economy and resources and the environment has become increasingly prominent. On the basis of limited land resources, the way to promote multi-objective comprehensive development such as economic, social development and ecological and environmental protection through structure and layout regulation, so as to maximize regional comprehensive benefits, is an important task of current land spatial planning. Our aim is to obtain land-use-change data in the study area using remote-sensing data inversion and multiple-model simulation. Based on land suitability evaluation, we predict and optimize the land use structure of the study area in 2030 and evaluate and compare ecosystem services. Based on remote-sensing images and eco-environmental data from 1985 to 2014 in the study area, land use/land cover change (LUCC) and future simulation data were obtained by using supervised classification, landscape metrics and the CA-Markov model. The ecosystem services were evaluated by the InVEST model. The analytic hierarchy process (AHP) method was used to evaluate the land suitability for LUCC. Finally, the LUCC in 2030 under two different scenarios, Scenario_1 (prediction) and Scenario_2 (optimization), were evaluated, and the ecosystem service functions were compared. In the last 30 years, the landscape in the study area has gradually fragmented, and the built-up land has expanded rapidly, increased by one-third, mainly at the cost of cropland, orchards and wasteland. According to the suitability evaluation, giving priority to the land use types with higher environmental requirements will ensure the study area has a higher ecosystem service value. The rapid development of urbanization has a far-reaching impact on regional LUCC. Intensive land resources need reasonable and scientific land use planning, and land use planning should be based on the suitability evaluation of land resources, which can improve the regional ecosystem service function.
Asunto(s)
Ecosistema , Urbanización , Beijing , China , Conservación de los Recursos Naturales , Desarrollo EconómicoRESUMEN
Herein, a rational design of SnS2 nanosheets confined into bubble-like carbon nanoreactors anchored on N,S doped carbon nanofibers (SnS2 @C/CNF) is proposed to prepare the self-standing electrodes, which provides tunable void space on carbon fibers for the first time by introducing hollow carbon nanoreactors. The SnS2 @C/CNF provides the stable support with greatly enhanced ion and electron transport, alleviates aggregation and volume expansion of SnS2 nanosheets, and promotes the formation of abundant exposed edges and active sites. The volume balance between SnS2 nanosheets and hollow carbon nanoreactors is reached to accommodate the expansion of SnS2 during cycles by controlling the thickness of SnO2 shells, which achieves the best space utilization. The doping of N,S elements enhances the wettability of the carbon nanofiber matrix to electrolyte and Li ions and further improves the electrical conductivity of the whole electrode. Thus, the SnS2 @C/CNF benefits greatly in structural stability and pseudocapacitive capacity for improved lithium/sodium storage performance. As a result of these improvements, the self-standing SnS2 @C/CNF film electrodes exhibit the highly stable capacity of 964.8 and 767.6 mAh g-1 at 0.2 A g-1 , and excellent capacity retention of 87.4% and 82.4% after 1000 cycles at high current density for lithium-ion batteries and sodium-ion batteries, respectively.
RESUMEN
Cobalt selenides based on the conversion reaction have been widely applied in lithium-ion batteries (LIBs) due to their high conductivity and high specific capacity. However, effectively suppressing the fast capacity fade caused by the irreversible Se/Co dissolution and serious volume change during the cycling process is still a challenge. Herein, a facile and efficient self-generated sacrificial template method is used to prepare Co0.85Se nanoparticles encapsulated in the inner wall of N-doped carbon matrix nanotubes (Co0.85Se@NCMT). In this strategy, the formation of stable Co-N/C and Se-C as well as enhancing the mechanical strength between active materials and N-doped carbon matrix nanotubes can critically affect the performance through suppressing the dissolution of Se/Co, decreasing energy band, promoting the shuttling of the ions/e- moving and mitigating the volume expansion during the charge-discharge process, which play a key role in improving the structure stability and electrochemical performance. Besides, Co0.85Se nanoparticles encapsulated in the robust carbon matrix inner wall can ensure good electron transfer and prevent the aggregation of nanoparticles, leading to superior electrochemical reversibility. Finally, carbon matrix nanotubes can provide sufficient space to effectively accommodate the volume changes of encapsulated Co0.85Se nanoparticles, thereby improving the cyclic stability. Based on the above advantages, as expected, the electrochemical investigations exhibited that the Co0.85Se@NCMT anode performs a stable reversible capacity of 462.9 mA h g-1 at a large current density of 5 A g-1 and a remarkable capacity retention of 99.5% after 800 cycles, suggesting its promising potential for the anode of LIBs.