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1.
Clin Oral Investig ; 28(6): 352, 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38822874

ABSTRACT

BACKGROUND: The relationship between tooth colour and individual satisfaction in oral aesthetics has long been a topic of interest. In this study, we utilized the fuzzy analytic hierarchy process (FAHP) to investigate the impacts of sex and age on tooth colour preference. The findings of this study should provide a scientific basis for oral aesthetic practice. METHODS: In the current study, a random selection method was employed, and a survey was completed by 120 patients. To obtain tooth colour data, standard tooth colour charts were used. Smile photos were taken as template images using a single-lens reflex camera. The FAHP was utilized to conduct a weight analysis of tooth colour preferences among patients of different sexes and age groups. RESULTS: There were significant differences in tooth colour preference based on sex and age. Men tend to prefer the B1 colour, while women may prioritize the aesthetic effects of other colours. Additionally, as patients age, their preferences for tooth colour become more diverse. These findings offer valuable insights for oral aesthetics practitioners, enabling them to better address the aesthetic needs of patients across different sexes and ages. This knowledge can aid in the development of more personalized treatment plans that align with patients' expectations. CONCLUSION: In this study, we utilized scientific analysis methods to quantify the popularity of different tooth colours among various groups of people. By doing so, we established a scientific foundation for clinical practice. The findings of this study offer valuable insights for oral aesthetic research, enhancing our understanding of tooth colour. Additionally, these findings have practical applications in the field of oral medicine, potentially improving patients' quality of life and overall oral health.


Subject(s)
Esthetics, Dental , Humans , Female , Male , Adult , Middle Aged , Sex Factors , Age Factors , Color , Surveys and Questionnaires , Smiling , Aged , Adolescent , Photography, Dental , Tooth , Patient Preference
2.
Org Biomol Chem ; 22(19): 3986-3994, 2024 05 15.
Article in English | MEDLINE | ID: mdl-38695061

ABSTRACT

Algae-based marine carbohydrate drugs are typically decorated with negative ion groups such as carboxylate and sulfate groups. However, the precise synthesis of highly sulfated alginates is challenging, thus impeding their structure-activity relationship studies. Herein we achieve a microwave-assisted synthesis of a range of highly sulfated mannuronate glycans with up to 17 sulfation sites by overcoming the incomplete sulfation due to the electrostatic repulsion of crowded polyanionic groups. Although the partially sulfated tetrasaccharide had the highest affinity for the receptor binding domain (RBD) of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant, the fully sulfated octasaccharide showed the most potent interference with the binding of the RBD to angiotensin-converting enzyme 2 (ACE2) and Vero E6 cells, indicating that the sulfated oligosaccharides might inhibit the RBD binding to ACE2 in a length-dependent manner.


Subject(s)
Angiotensin-Converting Enzyme 2 , Antiviral Agents , Microwaves , Polysaccharides , SARS-CoV-2 , SARS-CoV-2/drug effects , Antiviral Agents/pharmacology , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Chlorocebus aethiops , Angiotensin-Converting Enzyme 2/metabolism , Angiotensin-Converting Enzyme 2/antagonists & inhibitors , Angiotensin-Converting Enzyme 2/chemistry , Vero Cells , Polysaccharides/chemistry , Polysaccharides/pharmacology , Polysaccharides/chemical synthesis , Humans , Animals , Spike Glycoprotein, Coronavirus/antagonists & inhibitors , Spike Glycoprotein, Coronavirus/metabolism , Spike Glycoprotein, Coronavirus/chemistry , Hexuronic Acids/chemistry , Hexuronic Acids/pharmacology , Hexuronic Acids/chemical synthesis , Sulfates/chemistry , Sulfates/pharmacology , Sulfates/chemical synthesis , COVID-19 Drug Treatment , Structure-Activity Relationship
3.
Clin Exp Neuroimmunol ; 15(1): 55-60, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38595690

ABSTRACT

We report a rare case of paraneoplastic neurological syndrome with dual seropositivity of anti-aquaporin-4 and myelin oligodendrocyte glycoprotein antibodies in a 40 year-old woman with metastatic triple-negative breast cancer. She received multiple lines of anti-neoplastic treatment, including immunotherapy with pembrolizumab, as well as cytotoxic chemotherapy. Paraneoplastic meningoencephalomyelitis developed 2 years after diagnosis of breast cancer and 1 year after discontinuation of immunotherapy with pembrolizumab. She first developed longitudinally extending transverse myelitis followed by left optic neuritis and meningoencephalitis with new enhancing lesions in the brain and spinal leptomeninges. Cerebrospinal fluid analysis during both episodes showed normal glucose and protein, and elevated white blood cell count. Cytology was negative for malignancy. Cerebrospinal fluid was positive for neuromyelitis optica immunoglobulin G antibody anti-aquaporin-4, and autoimmune myelopathy panel was positive for myelin oligodendrocyte glycoprotein antibody. The patient had significant clinical and radiographic improvement after completion of five cycles of plasmapheresis followed by intravenous immunoglobulin. She did not have recurrence of paraneoplastic syndrome with maintenance rituximab every 6 months and daily low-dose prednisone. She succumbed to progressive systemic metastatic disease 4.5 years after her breast cancer diagnosis. This case shows that these antibodies can occur concurrently and cause clinical features, such as both neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody disease, in a patient with a singular type of cancer. We highlight the importance of testing for paraneoplastic etiology in cancer patients with radiographic menigoencephalomyelitis or meningitis with atypical symptoms of meningeal carcinomatosis and/or cerebrospinal fluid profile negative for leptomeningeal carcinomatosis.

4.
BMC Oral Health ; 24(1): 488, 2024 Apr 24.
Article in English | MEDLINE | ID: mdl-38658882

ABSTRACT

BACKGROUND: Orthodontics is a common treatment for malocclusion and is essential for improving the oral health and aesthetics of patients. Currently, patients often rely on the clinical expertise and professional knowledge of doctors to select orthodontic programs. However, they lack their own objective and systematic evaluation methods to quantitatively compare different programs. Therefore, there is a need for a more comprehensive and quantitative approach to selecting orthodontic treatment plans, aiming to enhance their scientific validity and effectiveness. METHODS: In this study, a combination of the analytic hierarchy process (AHP) and semantic analysis was used to evaluate and compare different orthodontic treatment options. An AHP model and evaluation matrix were established through thorough research and semantic analysis of patient requirements. This model considered various treatment factors. Expert panels were invited to rate these factors using a 1-9 scale. The optimal solution was determined by ranking and comparing different orthodontic treatment plans using the geometric mean method to calculate the weights of each criterion. RESULTS: The research indicates a higher preference for invisible correction compared to other orthodontic solutions, with a weight score that is 0.3923 higher. Factors such as comfort and difficulty of cleaning have been given significant attention. CONCLUSION: The Analytic Hierarchy Process (AHP) method can be utilized to effectively develop orthodontic treatment plans, making the treatment process more objective, scientific, and personalized. The design of this study offers strong decision support for orthodontic treatment, potentially improving orthodontic treatment outcomes in clinical practice and ultimately enhancing oral health and patients' quality of life.


Subject(s)
Malocclusion , Orthodontics, Corrective , Humans , Orthodontics, Corrective/methods , Malocclusion/therapy , Patient Care Planning , Decision Making , Clinical Decision-Making , Decision Support Techniques
5.
Curr Med Sci ; 44(2): 328-332, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38517677

ABSTRACT

OBJECTIVE: This study aimed to investigate the incidence of enteral nutrition intolerance (ENI) in patients with sepsis and explore potential risk factors. METHODS: A case-control study was conducted in patients with sepsis who were receiving enteral nutrition (EN) at a tertiary hospital in China. The included patients were divided into the ENI group and the non-ENI group. Univariate and multivariate analyses were performed to identify the risk factors for ENI. RESULTS: A total of 859 patients were included in the study. Among them, 288 (33.53%) patients experienced symptoms of ENI, including diarrhea, vomiting, bloating, and gastric retention. Logistic regression analysis revealed that the Acute Physiology and Chronic Health Evaluation H (APACHE H) score, thoracocentesis, and usage of cardiotonic drugs (namely, inotropes) were independent predictors of the ENI. CONCLUSION: The incidence of ENI is relatively high in patients with sepsis, especially in those who have higher APACHE H scores, have undergone thoracocentesis, and have received inotropes.


Subject(s)
Enteral Nutrition , Sepsis , Humans , Case-Control Studies , Nutritional Status , Sepsis/complications , Sepsis/epidemiology , Risk Factors
6.
BMC Public Health ; 24(1): 460, 2024 Feb 14.
Article in English | MEDLINE | ID: mdl-38355487

ABSTRACT

BACKGROUND: The COVID-19 pandemic has imposed unprecedented stress and challenges upon medical staff, potentially resulting in posttraumatic growth (PTG). This scoping review aims to synthesize the existing knowledge on PTG among medical staff during the pandemic by identifying its current status and potential influencing factors. The findings may provide a foundation for future research and interventions to enhance the medical staff's psychological resilience and well-being. METHODS: Literature was systematically searched on PTG among medical staff during the COVID-19 pandemic from 01 January 2020 to 31 December 2022. The following databases were searched: PubMed, Web of Science, Embase, CINAHL, PsycINFO, Cochrane Library, China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Service System (SinoMed), and Wanfang Data. Eligibility criteria included: (1) medical staff as research subjects; (2) a focus on "posttraumatic growth" or "alternative posttraumatic growth" related to the COVID-19 outbreak and pandemic; (3) discussion of the situation and influencing factors of PTG; and (4) study types, such as qualitative, quantitative, and mixed methods. Two researchers independently selected and extracted study characteristics (study design, study population, region, measurement instruments, and primary outcomes) from the included literature. The data were synthesized qualitatively and descriptively. RESULTS: Thirty-six papers from 12 countries met the inclusion criteria. Moderate PTG levels were observed among healthcare workers during the COVID-19 pandemic, with emphasis on "interpersonal relationships," "changes in life philosophy," and "growth in personal competence." Influencing factors included trauma exposure, sociodemographics, psychological characteristics (resilience and positive qualities), coping, and social support. CONCLUSIONS: This review discovered moderate PTG levels among medical staff during the COVID-19 pandemic, with critical areas in interpersonal relationships, life philosophy, and personal competence. The identified influencing factors can inform future research and interventions to enhance healthcare workers' psychological resilience and well-being.


Subject(s)
COVID-19 , Posttraumatic Growth, Psychological , Resilience, Psychological , Humans , Pandemics , Medical Staff
7.
Small ; 20(15): e2306237, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38009589

ABSTRACT

Manganese-based materials are regarded as the most prospective cathode materials because of their high natural abundance, low toxicity, and high specific capacity. Nevertheless, the low conductivity, poor cycling performance, and controversial energy storage mechanisms hinder their practical application. Here, the MnS0.5Se0.5 microspheres are synthesized by a two-step hydrothermal approach and employed as cathode materials for aqueous zinc-ion batteries (AZIBs) for the first time. Interestingly, in-depth ex situ tests and electrochemical kinetic analyses reveal that MnS0.5Se0.5 is first irreversibly converted into low-crystallinity ZnMnO3 and MnOx by in situ electrooxidation (MnS0.5Se0.5-EOP) during the first charging process, and then a reversible co-insertion/extraction of H+/Zn2+ occurs in the as-obtained MnS0.5Se0.5-EOP electrode during the subsequent discharging and charging processes. Benefiting from the increased surface area, shortened ion transport path, and stable lamellar microsphere structure, the MnS0.5Se0.5-EOP electrodes deliver high reversible capacity (272.8 mAh g-1 at 0.1 A g-1), excellent rate capability (91.8 mAh g-1 at 2 A g-1), and satisfactory cyclic stability (82.1% capacity retention after 500 cycles at 1 A g-1). This study not only provides a powerful impetus for developing new types of manganese-based chalcogenides, but also puts forward a novel perspective for exploring the intrinsic mechanisms of in situ electrooxidation behavior.

8.
Molecules ; 28(6)2023 Mar 08.
Article in English | MEDLINE | ID: mdl-36985464

ABSTRACT

In this work, CuS, Cu7S4, Cu9S5, Cu7.2S4, and Cu2S with the same morphology were successfully synthesized by the hydrothermal method. According to the calculation, their galvanostatic charge-discharge (GCD) curves were 43.29 (CuS), 86.3 (Cu7S4), 154 (Cu9S5), 185.4 (Cu7.2S4), and 206.9 F/g (Cu2S) at the current density of 1 A/g. The results showed that the energy storage capacity of copper sulfide with the same morphology increased with the increase of the copper sulfide stoichiometric coefficient. At the second part of this work, the agglomerated cuprous sulfide and the microporous cuprous sulfide were successfully prepared, respectively. In addition, the porous spherical cuprous sulfide was annealed to get nano cuprous sulfide. It is found that the specific capacity of the agglomerated structure is the highest, which had reached 206.9 F/g at the current density of 1 A/g, and 547.9 F/g at the current density of 10 A/g after activation.

9.
J Colloid Interface Sci ; 641: 831-841, 2023 Jul.
Article in English | MEDLINE | ID: mdl-36966572

ABSTRACT

Mo-based heterostructures offer a new strategy to improve the electronics/ion transport and diffusion kinetics of the anode materials for sodium-ion batteries (SIBs). MoO2/MoS2 hollow nanospheres have been successfully designed via in-situ ion exchange technology with the spherical coordination compound Mo-glycerates (MoG). The structural evolution processes of pure MoO2, MoO2/MoS2, and pure MoS2 materials have been investigated, illustrating that the structureofthenanospherecan be maintained by introducing the S-Mo-S bond. Based on the high conductivity of MoO2, the layered structure of MoS2 and the synergistic effect between components, as-obtained MoO2/MoS2 hollow nanospheres display enhanced electrochemical kinetic behaviors for SIBs. The MoO2/MoS2 hollow nanospheres achieve a rate performance with 72% capacity retention at a current of 3200 mA g-1 compared to 100 mA g-1. The capacity can be restored to the initial capacity after a current returns to 100 mA g-1, while the capacity fading of pure MoS2 is up to 24%. Moreover, the MoO2/MoS2 hollow nanospheres also exhibit cycling stability, maintaining a stable capacity of 455.4 mAh g-1 after 100 cycles at a current of 100 mA g-1. In this work, the design strategy for the hollow composite structure provides insight into the preparation of energy storage materials.

10.
Small ; 19(15): e2207975, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36631278

ABSTRACT

Transition metal selenides anodes with fast reaction kinetics and high theoretical specific capacity are expected to solve mismatched kinetics between cathode and anode in Li-ion capacitors. However, transition metal selenides face great challenges in the dissolution and shuttle problem of lithium selenides, which is the same as Li-Se batteries. Herein, inspired by the density functional theory calculations, heterogeneous can enhance the adsorption of Li2 Se relative to single component selenide electrodes, thus inhibiting the dissolution and shuttle effect of Li2 Se. A heterostructure material (denoted as CoSe2 /SnSe) with the ability to evolve continuously (CoSe2 /SnSe→Co/Sn→Co/Li13 Sn5 ) is successfully designed by employing CoSnO3 -MOF as a precursor. Impressively, CoSe2 /SnSe heterostructure material delivers the ultrahigh reversible specific capacity of 510 mAh g-1 after 1000 cycles at the high current density of 4 A g-1 . In situ XRD reveals the continuous evolution of the interface based on the transformation and alloying reactions during the charging and discharging process. Visualizations of in situ disassembly experiments demonstrate that the continuously evolving interface inhibits the shuttle of Li2 Se. This research proposes an innovative approach to inhibit the dissolution and shuttling of discharge intermediates (Li2 Se) of metal selenides, which is expected to be applied to metal sulfides or Li-Se and Li-S energy storage systems.

11.
Org Lett ; 24(45): 8381-8386, 2022 11 18.
Article in English | MEDLINE | ID: mdl-36346693

ABSTRACT

Pseudomonas aeruginosa is a leading cause of urinary tract, pulmonary, and wound infections and is becoming increasingly resistant to antibiotics. Here, we report the iodonium- and gold(I)-promoted bimodal glycosylation of glycosyl (Z)-ynenoates for highly ß-selective promoter-controlled synthesis and antigenic evaluation of a series of 1,2-cis-ß-linked mannuronic acid alginate glycans of P. aeruginosa up to a 24-mer, which represents the longest polymannuronic acid synthesized to date. By screening the six synthetic mannuronic acid alginate glycans with the mouse serum antibodies, we identified the mannuronic acid tetrasaccharide as the optimal antigen epitope for the development of vaccines against P. aeruginosa.


Subject(s)
Pseudomonas Infections , Pseudomonas aeruginosa , Mice , Animals , Pseudomonas Infections/prevention & control , Alginates , Hexuronic Acids
12.
J Colloid Interface Sci ; 611: 183-192, 2022 Apr.
Article in English | MEDLINE | ID: mdl-34952272

ABSTRACT

With the fast development of flexible wearable electronics, mobile electronic equipment, electric tool and electric vehicles, high specific capacity, superior cycle stability and excellent fast-charge performance are required for lithium-ion batteries (LIBs). Nevertheless, commercial graphite with the limited theoretical capacity (372 mAh g-1) and short lifespan is difficult to satisfy the requirements of the new generation of LIBs. In this work, the three-dimensional flexible molybdenum oxynitride (MNO) thin films with non-binder were prepared by magnetron sputtering approach. The charge transfer resistance and Li-ion diffusion coefficient were measured by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and the results show that molybdenum nitride is helpful to increase the diffusion and electron transfer of Li-ion. The MNO thin film annealed at 300 °C with irregular aggregate matrix structure shows a discharge capacity of 413 mAh g-1 after 180 cycles at 1 A g-1. The outstanding rate performance and cycle stability suggest that these binder-free thin film electrodes, especially nitrides, offer great opportunity for energy storage systems with fast-charge capabilities.

13.
Front Chem ; 8: 599981, 2020.
Article in English | MEDLINE | ID: mdl-33282842

ABSTRACT

Hierarchically nanoporous carbon materials (HNCMs) with well-defined morphology and excellent electrochemical properties are promising in fabrication of energy storage devices. In this work, we made a comparative study on the supercapacitive performances of HNCMs with different morphologies. To this end, four types of HNCMs with well-defined morphologies including submicrospheres (HNCMs-S), hexagonal nanoplates (HNCMs-N), dumbbell-like particles (HNCMs-D), and hexagonal microprisms (HNCMs-P) were successfully synthesized by dual-template strategy. The relationship of structural-electrochemical property was revealed by comparing the electrochemical performances of these HNCMs-based electrodes using a three-electrode system. The results demonstrated that the HNCMs-S-based electrode exhibited the highest specific capacitance of 233.8 F g-1 at the current density of 1 A g-1 due to the large surface area and well-defined hierarchically nanoporous structure. Moreover, the as-prepared HNCMs were further fabricated into symmetrical supercapacitor devices (HNCMs-X//HNCMs-X) using KOH as the electrolyte and their supercapacitive performances were checked. Notably, the assembled HNCMs-S//HNCMs-S symmetric supercapacitors displayed superior supercapacitive performances including high specific capacitance of 55.5 F g-1 at 0.5 A g-1, good rate capability (retained 71.9% even at 20 A g-1), high energy density of 7.7 Wh kg-1 at a power density of 250 W kg-1, and excellent cycle stability after 10,000 cycles at 1 A g-1. These results further revealed the promising prospects of the prepared HNCMs-S for high-performance energy storage devices.

14.
Org Lett ; 22(22): 8780-8785, 2020 11 20.
Article in English | MEDLINE | ID: mdl-33119312

ABSTRACT

Helicobacter pylori, the most common cause of chronic gastritis, peptic ulcers, and gastric cancers, infects around half of the world's population. Although the drawbacks of antibiotic-based combination therapy are emerging, no effective vaccine is available to prevent H. pylori infections. Here, we describe the total synthesis of the unique α-(1→3)-linked tri-d-glycero-d-manno-heptose antigen from the lipopolysaccharide of H. pylori serogroups O3 and O6 and strains MO19, D2, D4, and D5 based on de novo synthesis of the differentially protected d-glycero-d-manno-heptosyl building blocks. Immunization of mice with the semisynthetic glycoconjugate elicited a very robust T-cell-dependent antigen-specific immune response, resulting in very high titers of IgG1 and IgG2b protective antibody isotypes. The postimmune sera recognized H. pylori NCTC 11637 and bound strongly to the surface of the intact bacteria.


Subject(s)
Helicobacter pylori/immunology , Heptoses/chemical synthesis , Lipopolysaccharides/chemistry , Animals , Glycoconjugates/chemistry , Helicobacter pylori/chemistry , Heptoses/immunology , Mice , Molecular Structure , Vaccines/immunology
15.
Org Lett ; 22(20): 8018-8022, 2020 10 16.
Article in English | MEDLINE | ID: mdl-32991182

ABSTRACT

Synthesis of bacterial cell surface l-glycero-d-manno-heptose (l,d-Hep)- and d-glycero-d-manno-heptose (d,d-Hep)-containing higher carbon sugars is a challenging task. Here, we report a convenient and efficient approach for the synthesis of the l,d-Hep and d,d-Hep building blocks. Using l-lyxose and d-ribose as starting materials, this approach features diastereoselective Mukaiyama-type aldol reactions as the key steps. On the basis of the synthetic l,d-Hep and d,d-Hep building blocks, we achieved the first stereoselective synthesis of the unique α-l,d-Hep-(1→3)-α-d,d-Hep-(1→5)-α-Kdo core trisaccharide of the lipopolysaccharide of Vibrio parahemolyticus O2.


Subject(s)
Heptoses/chemical synthesis , Lipopolysaccharides/chemical synthesis , Trisaccharides/chemical synthesis , Vibrio/chemistry , Heptoses/chemistry , Lipopolysaccharides/chemistry , Molecular Structure , Trisaccharides/chemistry
16.
Front Chem ; 8: 409, 2020.
Article in English | MEDLINE | ID: mdl-32457879

ABSTRACT

Li metal batteries have been considered as the most promising batteries with high energy density for cutting-edge electronic devices such as electric vehicles, autonomous aircrafts, and smart grids. However, Li metal anode faces the issues of safety and capacity deterioration, which are closely related to Li dendrite growth. In this paper, we review the main strategies to improve the performance of Li metal anode. Due to Li dendrite's catastrophic influence, suppression of Li dendrite growth is prerequisite for each strategy. Apart from Li dendrite, interfacial resistance between electrolyte and electrode, ionic conductivity of electrolytes, mechanical strength, and volume fluctuation of Li metal anode are also discussed in these strategies. We outline these strategies based on the classifications of constructing solid electrolyte interphase, engineering of solid-state electrolyte and adopting matrix for Li metal anode. Each strategy is illustrated and discussed in detail by exemplification. For better understanding, some important theories related to Li metal anode have been also introduced. Finally, the outlooks for future research of Li metal anode are presented.

17.
J Colloid Interface Sci ; 573: 232-240, 2020 Aug 01.
Article in English | MEDLINE | ID: mdl-32278954

ABSTRACT

In this paper, double-layered mesopore-rich hollow carbon microspheres (DHCM) were prepared by a Stöber method using tetraethyl orthosilicate, resorcinol and formaldehyde as precursor materials, and further utilized as carbon sources to prepare the boron and nitrogen co-doped double-layered mesopore-rich hollow carbon microspheres (B, N-DHCM) by hydrothermal approach utilizing ammonium tetraborate tetrahydrate (NH4B5O8·4H2O) as boron and nitrogen sources. Compared with the undoped DHCM, the as-obtained B, N-DHCM displays improved capacitive properties with a high specific capacitance (221.5 F g-1 at 1 A g-1), good rate performance (104.1 F g-1 at 20 A g-1) and superior cycle life (91% of capacitance retention at 3 A g-1 after 10,000 cycles). The outstanding capacitive performances result from the synergistic effect of the unique double-layered mesopore-rich hollow structure contributing to the rate property and cycle stability and the modification of B and N co-doping providing pseudocapacitance for the enhancement of specific capacitance. Therefore, the excellent capacitive behaviors render the B, N-DHCM promising electrode materials for application in supercapacitors and other energy storage systems.

18.
Front Chem ; 8: 232, 2020.
Article in English | MEDLINE | ID: mdl-32296683

ABSTRACT

Polymer electrolytes for Li metal batteries (LMBs) should be modified to improve their ionic conductivity and stability against the lithium electrode. In this study, graphene oxide (GO) was modified by ion liquid (IL), and the IL modified GO (GO-IL) had been used as a filler for polyethylene oxide (PEO). The obtained solid polymer electrolyte (SPE) is of high ionic conductivity, low crystallinity and excellent stability against the lithium electrode. The PEO/GO-IL was characterized by various techniques, and its structure and performance were analyzed in detail. By addition of 1% GO-IL, the ionic conductivity of the PEO/GO-IL SPE reaches 1.8 × 10-5 S cm-1 at 25°C, which is 10 times higher than PEO (1.7 × 10-6 S cm-1), and the current density for stable Li plating/stripping in PEO/GO-IL can be increased to 100 µA cm-2 at 60°C. LiFePO4/Li cell (using PEO/GO-IL SPE) tests indicated that the initial discharge capacity can reach ~145 mA h g-1 and capacity retention can maintain 88% even after 100 cycles at a rate of 0.1C and at 60°C. Our creative work could provide a useful method to develop SPEs with excellent performance, thus accelerating the commercial application of LMBs.

19.
Front Chem ; 8: 150, 2020.
Article in English | MEDLINE | ID: mdl-32185164

ABSTRACT

In this study, two kinds of composites with the structure of graphene oxide (GO) sheets wrapped magnetic nanoparticles were investigated on their regeneration. The composites have a similar core-shell structure, but the interactions between the core and shell are quite different, which are electrostatic and covalent. They were characterized by scanning/transmission electron microscopy, power X-ray diffraction, and vibrating sample magnetometer analysis. Their morphologies and structures of the samples had been revealed using methylene blue and Pb(II) as adsorbates during regeneration. The results showed that the composites with covalent bonding interaction could maintain a stable core-shell structure and present a good regeneration performance for adsorption-desorption of methylene blue and Pb(II). The composites with electrostatic interaction could approximately preserve its core-shell structure and could be recyclable for adsorption-desorption of methylene blue, however, they would disintegrate its core-shell structure during adsorption/desorption of Pb(II), thus greatly decreasing their regeneration performance. The regeneration mechanisms of the composites were analyzed, which could provide a useful theoretical guide to design the GO sheets wrapped magnetic nanoparticles composites.

20.
Nanomicro Lett ; 12(1): 16, 2020 Jan 04.
Article in English | MEDLINE | ID: mdl-34138066

ABSTRACT

Carbon quantum dots (CQDs) as a new class of emerging materials have gradually drawn researchers' concern in recent years. In this work, the graphitic CQDs are prepared through a scalable approach, achieving a high yield with more than 50%. The obtained CQDs are further used as structure-directing and conductive agents to synthesize novel N,S-CQDs/NiCo2S4 composite cathode materials, manifesting the enhanced electrochemical properties resulted from the synergistic effect of highly conductive N,S-codoped CQDs offering fast electronic transport and unique micro-/nanostructured NiCo2S4 microspheres with Faradaic redox characteristic contributing large capacity. Moreover, the nitrogen-doped reduced graphene oxide (N-rGO)/Fe2O3 composite anode materials exhibit ultrahigh specific capacity as well as significantly improved rate property and cycle performance originating from the high-capacity prism-like Fe2O3 hexahedrons tightly wrapped by highly conductive N-rGO. A novel alkaline aqueous battery assembled by these materials displays a specific energy (50.2 Wh kg-1), ultrahigh specific power (9.7 kW kg-1) and excellent cycling performance with 91.5% of capacity retention at 3 A g-1 for 5000 cycles. The present research offers a valuable guidance for the exploitation of advanced energy storage devices by the rational design and selection of battery/capacitive composite materials.

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