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1.
Article in English | MEDLINE | ID: mdl-37694359

ABSTRACT

Circular RNAs (circRNAs) have been reported to participate in the development of various diseases. In this study, we investigated the potential mechanism underlying the role of circRNAs in atherosclerosis. Human umbilical vein endothelial cells (HUVECs) were treated with 100µg/mL oxidized low-density lipoprotein (ox-LDL) to simulate atherosclerosis. We observed that hsa_circ_0006867 (circ_0006867), a circRNA markedly increased in ox-LDL-treated endothelial cells, acted as a molecular sponge of miR-499a-3p and regulated its expression. This interaction led to changes in the downstream target gene ADAM10, thus affecting cell apoptosis and migration. Thus, our study suggests that circ_0006867 regulates ox-LDL-induced endothelial injury via the circ_0006867/miR-499a-3p/ADAM10 axis, indicating its potential as an exploitable therapeutic target for atherosclerosis.

2.
Medicine (Baltimore) ; 101(33): e29994, 2022 Aug 19.
Article in English | MEDLINE | ID: mdl-35984125

ABSTRACT

Changes in the ST-segment in aVR of electrocardiogram have been used to predict the morbidity of left main and/or 3-vessel disease (LM/3-VD) in patients with acute coronary syndrome (ACS). However, the association with patient prognosis has rarely been reported. A total of 274 patients diagnosed with ACS were retrospectively evaluated following allocation into 1 of 3 groups: the ST-segment elevation (STE) group ≥ 0.05 mV, ST-segment depression (STD) group ≥ 0.05 mV, and the Isoelectric group in aVR. A comparison of clinical characteristics, coronary angiography results, major adverse cardiovascular events (MACE), and GRACE risk score was made. Patients in the STE and STD groups were older and had a lower LVEF, a greater number of MACE and higher GRACE risk score, compared with patients in the isoelectric group. Patients in the STE group had significantly greater morbidity due to LM/3-VD than did the non-STE groups. In addition, as the amplitude of STE in aVR increased, the number of MACE, GRACE risk score, and the incidence of LM/3-VD increased. Furthermore, after adjusting for other clinical factors, multivariate statistical results indicated that STE ≥ 0.05 mV in aVR was the only predictor of LM/3-VD, whereas STD ≥ 0.05 mV was not. It was found that STE or STD ≥ 0.05 mV in aVR was an independent predictor of MACE. STE ≥ 0.05 mV in aVR is associated with LM/3-VD. Furthermore, ST-segment deviation in aVR may have prognostic value of MACE and associated with higher GRACE risk scores in patients with ACS.


Subject(s)
Acute Coronary Syndrome , Coronary Artery Disease , Sexually Transmitted Diseases , Acute Coronary Syndrome/diagnosis , Arrhythmias, Cardiac , Coronary Angiography/methods , Coronary Artery Disease/diagnosis , Electrocardiography/methods , Humans , Prognosis , Retrospective Studies
3.
Iran J Basic Med Sci ; 25(6): 781-788, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35949313

ABSTRACT

Objectives: Lysine-specific demethylase1 (LSD1), an important class of histone demethylases, plays a crucial role in regulation of mammalian biology. The up-regulated LSD1 expression was frequently associated with progress and oncogenesis of multiple human cancers, including non-small cell lung cancer (NSCLC). Therefore, inhibition of LSD1 may provide an attractive strategy for cancer treatment. We investigated the effect of sanguinarine against lung cancer cells as a natural alkaloid LSD1 inhibitor. Materials and Methods: The inhibition properties of sanguinarine to the recombinant LSD1 were evaluated by a fluorescence-based method. Subsequently, assays such as viability, apoptosis, clonogenicity, wound healing, and transwell were performed on H1299 and H1975 cells after treatment with sanguinarine. Results: Upon screening our in-house natural chemical library toward LSD1, we found that sanguinarine possessed a potent inhibitory effect against LSD1 with the IC50 value of 0.4 µM in a reversible manner. Molecular docking simulation suggested that sanguinarine may inactivate LSD1 by inserting into the binding pocket of LSD1 to compete with the FAD site. In H1299 and H1975 cells, sanguinarine inhibited the demethylation of LSD1, validating its cellular activity against the enzyme. Further studies showed that sanguinarine exhibited a strong capacity to suppress colony formation, inhibit migration and invasion, as well as induce apoptosis of H1299 and H1975 cells. Conclusion: Our findings present a new chemical scaffold for LSD1 inhibitors, and also provide new insight into the anti-NSCLC action of sanguinarine.

4.
J Healthc Eng ; 2022: 8575305, 2022.
Article in English | MEDLINE | ID: mdl-35313511

ABSTRACT

With the continuous development of internet information computing, the continuous improvement of medical and health systems, and the continuous increase of medical big data, traditional operating room care also needs to be further optimized. Medical big data is a forum data set for medical industry healthcare, electronic medical record information, clinical case record information, medical financial data, remote patient monitoring data, clinical decision support data, medical insurance data set, online consulting platform, and so on. Gastrointestinal tumors are currently one of the largest malignant tumors. Compared with ordinary patients, the presence of fear, depression, irritability, and other unhealthy emotions in patients with gastrointestinal tumors will reduce the therapeutic effect. Without careful care, the use of chemotherapy and other treatments makes patients vulnerable to various side effects. This article aims to study the use of medical big data intelligent algorithms to perform detailed care for patients during gastrointestinal tumor surgery and analyze the effects of care. This paper proposes an improved DNN algorithm; the DNN algorithm is to use several weight coefficient matrices and bias vectors to perform a series of linear operations and activation operations with the input value vector, starting from the input layer, backward calculation layer by layer, until the operation reaches the output layer, and the output result is obtained. This algorithm is used to study the theory, use mathematical formulas for method calculation and model design, and use the model to carry out detailed nursing experiments in the relevant operating room. The results of the experiment show that patients who have performed detailed care have a 27.2% improvement in treatment and rehabilitation effects than those who have not, and the level of detailed care has an obvious positive relationship with the rate of condition conversion. In the end, the hospital's detailed care quality evaluation index, which is QEI, increases by 1 point, which can increase the rate of condition conversion by 0.4.


Subject(s)
Decision Support Systems, Clinical , Gastrointestinal Neoplasms , Algorithms , Big Data , Gastrointestinal Neoplasms/surgery , Humans , Operating Rooms
5.
IEEE Trans Pattern Anal Mach Intell ; 44(10): 6024-6042, 2022 10.
Article in English | MEDLINE | ID: mdl-34061739

ABSTRACT

We present the first systematic study on concealed object detection (COD), which aims to identify objects that are visually embedded in their background. The high intrinsic similarities between the concealed objects and their background make COD far more challenging than traditional object detection/segmentation. To better understand this task, we collect a large-scale dataset, called COD10K, which consists of 10,000 images covering concealed objects in diverse real-world scenarios from 78 object categories. Further, we provide rich annotations including object categories, object boundaries, challenging attributes, object-level labels, and instance-level annotations. Our COD10K is the largest COD dataset to date, with the richest annotations, which enables comprehensive concealed object understanding and can even be used to help progress several other vision tasks, such as detection, segmentation, classification etc. Motivated by how animals hunt in the wild, we also design a simple but strong baseline for COD, termed the Search Identification Network (SINet). Without any bells and whistles, SINet outperforms twelve cutting-edge baselines on all datasets tested, making them robust, general architectures that could serve as catalysts for future research in COD. Finally, we provide some interesting findings, and highlight several potential applications and future directions. To spark research in this new field, our code, dataset, and online demo are available at our project page: http://mmcheng.net/cod.


Subject(s)
Algorithms , Image Interpretation, Computer-Assisted , Animals , Image Interpretation, Computer-Assisted/methods
6.
IEEE Trans Pattern Anal Mach Intell ; 44(8): 4339-4354, 2022 08.
Article in English | MEDLINE | ID: mdl-33600309

ABSTRACT

In this article, we conduct a comprehensive study on the co-salient object detection (CoSOD) problem for images. CoSOD is an emerging and rapidly growing extension of salient object detection (SOD), which aims to detect the co-occurring salient objects in a group of images. However, existing CoSOD datasets often have a serious data bias, assuming that each group of images contains salient objects of similar visual appearances. This bias can lead to the ideal settings and effectiveness of models trained on existing datasets, being impaired in real-life situations, where similarities are usually semantic or conceptual. To tackle this issue, we first introduce a new benchmark, called CoSOD3k in the wild, which requires a large amount of semantic context, making it more challenging than existing CoSOD datasets. Our CoSOD3k consists of 3,316 high-quality, elaborately selected images divided into 160 groups with hierarchical annotations. The images span a wide range of categories, shapes, object sizes, and backgrounds. Second, we integrate the existing SOD techniques to build a unified, trainable CoSOD framework, which is long overdue in this field. Specifically, we propose a novel CoEG-Net that augments our prior model EGNet with a co-attention projection strategy to enable fast common information learning. CoEG-Net fully leverages previous large-scale SOD datasets and significantly improves the model scalability and stability. Third, we comprehensively summarize 40 cutting-edge algorithms, benchmarking 18 of them over three challenging CoSOD datasets (iCoSeg, CoSal2015, and our CoSOD3k), and reporting more detailed (i.e., group-level) performance analysis. Finally, we discuss the challenges and future works of CoSOD. We hope that our study will give a strong boost to growth in the CoSOD community. The benchmark toolbox and results are available on our project page at https://dpfan.net/CoSOD3K.


Subject(s)
Algorithms , Image Interpretation, Computer-Assisted , Semantics
7.
Article in English | MEDLINE | ID: mdl-33861691

ABSTRACT

Existing RGB-D salient object detection (SOD) models usually treat RGB and depth as independent information and design separate networks for feature extraction from each. Such schemes can easily be constrained by a limited amount of training data or over-reliance on an elaborately designed training process. Inspired by the observation that RGB and depth modalities actually present certain commonality in distinguishing salient objects, a novel joint learning and densely cooperative fusion (JL-DCF) architecture is designed to learn from both RGB and depth inputs through a shared network backbone, known as the Siamese architecture. In this paper, we propose two effective components: joint learning (JL), and densely cooperative fusion (DCF). The JL module provides robust saliency feature learning by exploiting cross-modal commonality via a Siamese network, while the DCF module is introduced for complementary feature discovery. Comprehensive experiments using 5 popular metrics show that the designed framework yields a robust RGB-D saliency detector with good generalization. As a result, JL-DCF significantly advances the SOTAs by an average of ~2.0% (F-measure) across 7 challenging datasets. In addition, we show that JL-DCF is readily applicable to other related multi-modal detection tasks, including RGB-T SOD and video SOD, achieving comparable or better performance.

8.
J Thorac Dis ; 13(2): 831-836, 2021 Feb.
Article in English | MEDLINE | ID: mdl-33717556

ABSTRACT

BACKGROUND: The aim of this study was to summarize the clinical experience of extracorporeal cardiopulmonary resuscitation (ECPR) in the treatment of adult patients with refractory cardiac arrest. METHODS: The clinical data of 12 cases of adult patients with cardiac arrest hospitalized between June 2015 and September 2019 who were unable to achieve return of spontaneous circulation effectively with conventional cardiopulmonary resuscitation (CCPR) and were treated with ECPR technology were retrospectively analyzed. The group included six males and six females aged between 18 and 69 years. All the patients underwent veno-arterial extracorporeal membrane oxygenation (V-A ECMO) support with the adoption of femoral artery and vein catheterization. RESULTS: The duration of cardiopulmonary resuscitation (CPR) for the 12 patients was 32-125 min, and the ECMO duration was 2-190 h. Four patients were successfully weaned from ECMO and survived until hospital discharge. The other eight patients died in hospital; hemodynamic collapse (four patients) in the early stage of ECMO and severe neurological complications (three patients) were the main causes of death. CONCLUSIONS: Single-center data showed that ECPR provided a new rescue alternative for some patients with reversible refractory cardiac arrest. We have demonstrated that the success rate of treatment could be improved by selecting suitable patients and reducing the CPR duration as much as possible.

9.
IEEE Trans Med Imaging ; 39(8): 2626-2637, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32730213

ABSTRACT

Coronavirus Disease 2019 (COVID-19) spread globally in early 2020, causing the world to face an existential health crisis. Automated detection of lung infections from computed tomography (CT) images offers a great potential to augment the traditional healthcare strategy for tackling COVID-19. However, segmenting infected regions from CT slices faces several challenges, including high variation in infection characteristics, and low intensity contrast between infections and normal tissues. Further, collecting a large amount of data is impractical within a short time period, inhibiting the training of a deep model. To address these challenges, a novel COVID-19 Lung Infection Segmentation Deep Network (Inf-Net) is proposed to automatically identify infected regions from chest CT slices. In our Inf-Net, a parallel partial decoder is used to aggregate the high-level features and generate a global map. Then, the implicit reverse attention and explicit edge-attention are utilized to model the boundaries and enhance the representations. Moreover, to alleviate the shortage of labeled data, we present a semi-supervised segmentation framework based on a randomly selected propagation strategy, which only requires a few labeled images and leverages primarily unlabeled data. Our semi-supervised framework can improve the learning ability and achieve a higher performance. Extensive experiments on our COVID-SemiSeg and real CT volumes demonstrate that the proposed Inf-Net outperforms most cutting-edge segmentation models and advances the state-of-the-art performance.


Subject(s)
Coronavirus Infections/diagnostic imaging , Pneumonia, Viral/diagnostic imaging , Supervised Machine Learning , Tomography, X-Ray Computed/methods , Algorithms , Betacoronavirus , COVID-19 , Humans , Lung/diagnostic imaging , Pandemics , SARS-CoV-2
10.
Preprint in English | bioRxiv | ID: ppbiorxiv-993386

ABSTRACT

A novel coronavirus (2019-nCoV) outbreak has caused a global pandemic resulting in tens of thousands of infections and thousands of deaths worldwide. The RNA-dependent RNA polymerase (RdRp, also named nsp12), which catalyzes the synthesis of viral RNA, is a key component of coronaviral replication/transcription machinery and appears to be a primary target for the antiviral drug, remdesivir. Here we report the cryo-EM structure of 2019-nCoV full-length nsp12 in complex with cofactors nsp7 and nsp8 at a resolution of 2.9-[A]. Additional to the conserved architecture of the polymerase core of the viral polymerase family and a nidovirus RdRp-associated nucleotidyltransferase (NiRAN) domain featured in coronaviral RdRp, nsp12 possesses a newly identified {beta}-hairpin domain at its N-terminal. Key residues for viral replication and transcription are observed. A comparative analysis to show how remdesivir binds to this polymerase is also provided. This structure provides insight into the central component of coronaviral replication/transcription machinery and sheds light on the design of new antiviral therapeutics targeting viral RdRp. One Sentence SummaryStructure of 2019-nCov RNA polymerase.

11.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-828695

ABSTRACT

OBJECTIVE@#To study the significance of the level of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) in serum and bronchoalveolar lavage fluid (BALF), Acute Physiology and Chronic Health Evaluation II (APACHE II) score, and Sequential Organ Failure Assessment (SOFA) score in evaluating the conditions and prognosis of children with severe pneumonia.@*METHODS@#A total of 76 children with severe pneumonia who were admitted from August 2017 to October 2019 were enrolled as the severe pneumonia group. According to the treatment outcome, they were divided into a non-response group with 34 children and a response group with 42 children. Ninety-four children with common pneumonia who were admitted during the same period of time were enrolled as the common pneumonia group. One hundred healthy children who underwent physical examination in the outpatient service during the same period of time were enrolled as the control group. The serum level of sTREM-1, APACHE II score, and SOFA score were measured for each group, and the level of sTREM-1 in BALF was measured for children with severe pneumonia. The correlation of the above indices with the severity and prognosis of severe pneumonia in children was analyzed.@*RESULTS@#The severe pneumonia group had significantly higher serum sTREM-1 level, APACHEII score, and SOFA score than the common pneumonia group and the control group (P0.05).@*CONCLUSIONS@#The level of sTREM-1 in serum and BALF and SOFA score can be used to evaluate the severity and prognosis of severe pneumonia in children.


Subject(s)
Child , Humans , APACHE , Bronchoalveolar Lavage Fluid , Organ Dysfunction Scores , Pneumonia , Prognosis , ROC Curve , Sepsis , Triggering Receptor Expressed on Myeloid Cells-1
12.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-802165

ABSTRACT

Objective:To study the protective effect of dihydroartemisinin (DHA) on adjuvant-induced arthritis (AIA) and collagen-induced arthritis (CIA) in rats, in order to explore its possible mechanism. Method:Wistar rats were randomly divided into eight groups, namely AIA control group, AIA model group, AIA DHA group and AIA methotrexate group, CIA control group, CIA model group, CIA DHA group and CIA methotrexate group. To establish adjuvant-induced arthritis (AIA) model, rheumatoid arthritis rats were induced through intradermal injection with 0.1 mL Freund's complete adjuvant (FCA) into right postpedes except for the control group. To establish the model of collagen-induced arthritis (CIA), except for control group, the caudal root of rats was immunized subcutaneously with 0.2 mL of emulsion containing 1 g·L-1 of Collagen type Ⅱ (CⅡ). One week later, CⅡ emulsion was injected for the second time. After the rheumatoid arthritis model was successfully established and the administration with DHA (30 mg·kg-1·d-1), the anti-inflammatory effect of DHA on AIA/CIA rats was observed, including the arthritis index (AI), paw swelling degree and effect of DHA on immune organ index of AIA/CIA rats. Interleukin (IL)-6 levels in serum was detected by enzyme-linked immunosorbent assay (ELISA) and pathological sections of ankle joints of AIA/CIA rats. RAW264.7 macrophage cells were cultured in vitro and treated with DHA at various doses (0.5, 1, 2, 4, 8, 16 μmol·L-1) for 24 h, and the cell viability was detected by methyl thiazolyl tetrazolium(MTT) assay. Lipopolysaccharides (LPS) group, LPS+DHA groups (0.5, 1, 2 μmol·L-1) and control group were established. The level of IL-6 was detected by enzyme-linked immunosorbent assay(ELISA). The protein expression levels of nuclear transcription factor-κB p65 (NF-κB p65) was tested by Western blot. Result:Compared with control group, the paw swelling, AI, spleen index and IL-6 levels of model group were significantly increased (PPPPPPPP-1) groups had a remarkable effect on the cell viability (PP-1. The level of IL-6 and the protein expression of NF-κB p65 in LPS group were higher than those of control group. Compared with LPS group, DHA (0.5 μmol·L-1) groups could significantly reduce the secretion of IL-6 (PκB p65. Conclusion:DHA can alleviate the ankle joint lesion on rheumatoid arthritis rats. Its mechanism may be related to NF-κB signal pathway.

13.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-905714

ABSTRACT

Objective:To compare the clinical efficacy of rehabilitation training at different stages on patients with anterior talofibular ligament injury after conservative treatment. Methods:From October 2017 to October 2018, 58 patients with anterior talofibular ligament injury were divided into six-week rehabilitation group (n = 29) and twelve-week rehabilitation group (n = 29), according to the time they began rehabilitation after injury. Visual Analogue Score (VAS) and American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot function scoring system were used to evaluate ankle function before rehabilitation, and two weeks, four weeks and eight weeks after rehabilitation, respectively. Results:Two weeks, four weeks and eight weeks after rehabilitation, the scores of VAS and AOFAS improved in both groups (|t| > 4.137, P < 0.001), the scores of VAS were lower (|t| > 3.110, P < 0.01), and the scores of AOFAS were higher (|t| > 3.016, P < 0.01) in the six-week rehabilitation group than in the twelve-week rehabilitation group. Conclusion:It is suggested to begin rehabilitation within six weeks for patients with anterior talofibular ligament injury after conservative treatment.

14.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-905708

ABSTRACT

Objective:To investigate the effect of cardiopulmonary rehabilitation on motor function recovery in stroke patients. Methods:From February, 2018 to February, 2019, 100 stroke patients in convalescence stage were enrolled in this study. They were divided into control group (n = 50) and observation group (n = 50). The control group received routine rehabilitation, while the observation group received cardiopulmonary rehabilitation in addition. They were assessed with Fugl-Meyer Assessment (FMA), Self-rating Anxiety Scale (SAS), Self-rating Depression Scale (SAS) and pulmonary function test before and after treatment. Results:After treatment, the scores of FMA increased in both groups (t > 2.459, P < 0.05), which were higher in the observation group than in the control group (t = 2.678, P = 0.005); the scores of SAS and SDS decreased in both groups (t > 2.009, P < 0.05), which were lower in the observation group than in the control group (t > 3.261, P < 0.01); most of the forced vital capacity (FVC), the forced expiratory volume in 1 second (FEV1) and FEV1/FVC increased in both groups (t > 2.249, P < 0.05), which were higher in the observation group than in the control group (t > 2.147, P < 0.05). Conclusion:Cardiopulmonary rehabilitation could further promote the recovery of motor function of stroke patients, and improve the emotion and pulmonary function.

15.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-905681

ABSTRACT

Objective:To investigate the feasibility of movement posture and electromyography based upper-limb motor function assessment system in the assessment of upper-limb motor function for stroke patients. Methods:From January, 2018 to March, 2019, ten stroke patients were recruited from Nanjing Tongren Hospital. According to the predesigned rehabilitation movements, movement posture and surface electromyography data during rehabilitation movement implementation were collected, and the upper-limb motor function of stroke patients were evaluated using movement posture and electromyography based upper-limb motor function assessment system. Further comparisons were also made with single movement posture or electromyography based assessment system. Meanwhile, the validity of the proposed assessment system was verified. All the patients were assessed with Fugl-Meyer Assessment-Upper Extremities (FMA-UE). Results:Positive correlations were shown between movement posture and electromyography based upper-limb motor function assessment system and scores of FMA-UE (r = 0.891, P = 0.001), and better validities were achieved than single movement posture (r = 0.758, P = 0.011) or electromyography (r = 0.697, P = 0.025) based assessment. Conclusion:Movement posture and electromyography based upper-limb motor function assessment system can effectively evaluate the upper-limb motor function of stroke patients.

16.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-773144

ABSTRACT

In this study,in order to detect the antimicrobial activity of artemisinin and its derivatives artesunate and dihydroartemisinin,two methods including broth dilution and plate punching method were used to detect the antibacterial activity against gram-negative bacteria(Escherichia coli)and gram-positive bacteria(Staphylococcus aureus)of artemisinin,dihydroartemisinin and artesunate at various concentrations within 5 mmol·L~(-1)and at four time points(8,16,24,32 h).Two antibacterial positive drugs,streptomycin against E.coli and penicillin against S.aureus,were used as positive controls.Plate punching method showed that,unlike the results of 5 mmol·L~(-1)dihydroartemisinin or artesunate,no inhibition zone was detected at the same concentration of artemisinin after 24 h-treatment against E.coli.Broth dilution method showed that,the antibacterial activity of dihydroartemisinin against E.coli.was stronger than those of both artesunate and artemisinin;IC_(50)at24 h-treatment was 155.9μmol·L~(-1)for dihydroartemisinin,370.0μmol·L~(-1)for artesunate and none for artemisinin.Interestingly,dihydroartemisinin and artesunate showed the strongest antibacterial activity between 16-24 h,while artemisinin showed relatively stronger antibacterial activity between 8-16 h.Dihydroartermisinin showed no antibacterial activity against S.aureus.Above all,the antibacterial activity of artemisinins against E.coli is dihydroartemisinin>artesunate>artemisinin.Artemisinin and its derivatives have showed different antibacterial kinetics,and no antibacterial activity against S.aureus.has been detected with dihydroartemisinin.


Subject(s)
Anti-Bacterial Agents , Pharmacology , Artemisinins , Pharmacology , Artesunate , Pharmacology , Escherichia coli , Microbial Sensitivity Tests , Staphylococcus aureus
18.
ACS Appl Mater Interfaces ; 5(22): 12120-6, 2013 Nov 27.
Article in English | MEDLINE | ID: mdl-24191701

ABSTRACT

LiMn1-xFexPO4/C (x = 0 and 0.3) with a uniform carbon coating and interspersed carbon particles was prepared by a high-energy ball-milling (HEBM)-assisted solid-state reaction. The as-synthesized LiMn0.7Fe0.3PO4/C delivered an excellent rate performance as a LiMnPO4 class of materials. Specifically, the specific discharge capacity was 164 mAh/g (96% of theoretical value) at the 0.05 C rate and 107 mAh/g at the 5 C rate (1 C = 170 mA/g). Electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) measurements indicated improvements in the transport of electrons and Li(+) as well as the emergence of a single-phase region in lithium extraction and insertion reactions.

19.
ACS Nano ; 7(12): 10870-8, 2013 Dec 23.
Article in English | MEDLINE | ID: mdl-24256545

ABSTRACT

TiO2 nanoparticles aggregated into a regular ball-in-ball morphology were synthesized by hydrothermal processing and converted to carbon-encapsulated F-doped Li4Ti5O12 (LTO) composites (C-FLTO) by solid state lithiation at high temperatures. Through the careful control of the amount of carbon precursor (D(+)-glucose monohydrate) used in the process, LTO encapsulated with a continuous layer of nanoscale carbon was formed. The carbon encapsulation served a dual function: preserving the ball-in-ball morphology during the transformation from TiO2 to LTO and decreasing the external electron transport resistance. The fluoride doping of LTO not only increased the electron conductivity of LTO through trivalent titanium (Ti(3+)) generation, but also increased the robustness of the structure to repeated lithiation and delithiation. The best-performing composite, C-FLTO-2, therefore delivered a very satisfying performance for a LTO anode: a high charge capacity of ∼158 mA h g(-1) at the 1 C rate with negligible capacity fading for 200 cycles and an extremely high rate performance up to 140 C.

20.
Nanoscale ; 5(17): 7890-6, 2013 Sep 07.
Article in English | MEDLINE | ID: mdl-23851576

ABSTRACT

Two-dimensional nanosheets can leverage on their open architecture to support facile insertion and removal of Li(+) as lithium-ion battery electrode materials. In this study, two two-dimensional nanosheets with complementary functions, namely nitrogen-doped graphene and few-layer WS2, were integrated via a facile surfactant-assisted synthesis under hydrothermal conditions. The layer structure and morphology of the composites were confirmed by X-ray diffraction, scanning electron microscopy and high-resolution transmission microscopy. The effects of surfactant amount on the WS2 layer number were investigated and the performance of the layered composites as high energy density lithium-ion battery anodes was evaluated. The composite formed with a surfactant : tungsten precursor ratio of 1 : 1 delivered the best cyclability (average of only 0.08% capacity fade per cycle for 100 cycles) and good rate performance (80% capacity retention with a 50-fold increase in current density from 100 mA g(-1) to 5000 mA g(-1)), and may find uses in power-oriented applications.


Subject(s)
Electric Power Supplies , Graphite/chemistry , Lithium/chemistry , Electrochemical Techniques , Ions/chemistry , Metals/chemistry , Oxides/chemistry
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