52 results on '"Yunchao Li"'
Search Results
2. A high-performance biochar produced from bamboo pyrolysis with in-situ nitrogen doping and activation for adsorption of phenol and methylene blue
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Yunchao Li, Bo Xing, Zhenhao Li, Yan Ding, and Shurong Wang
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Environmental Engineering ,General Chemical Engineering ,technology, industry, and agriculture ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Biochemistry ,chemistry.chemical_compound ,Adsorption ,020401 chemical engineering ,chemistry ,Specific surface area ,Desorption ,Biochar ,Urea ,Phenol ,0204 chemical engineering ,0210 nano-technology ,Pyrolysis ,Methylene blue ,Nuclear chemistry - Abstract
Nitrogen doping is a promising method for the preparation of functional carbon materials. In this study, a nitrogen-doped porous coral biochar was prepared by using bamboo as raw material, urea as nitrogen source, and KHCO3 as green activator through in-situ pyrolysis. The structure of the obtained biochar was characterized by various techniques including nitrogen adsorption and desorption, Raman spectroscopy, X-ray photoelectron spectrometer, and etc. The adsorption properties of nitrogen-doped biochar were evaluated with phenol and methylene blue probes. The results showed that the nitrogen source ratio had a significant effect on the evolution of pore structure of biochar. Low urea addition ratio was beneficial to the development of pore structures. The optimum specific surface area of nitrogen-doped biochar could be up to 1693 m2·g-1. Nitrogen doping can effectively improve the adsorption capacity of biochar to phenol and methylene blue. Biochar prepared at 973.15 K with low urea addition ratio exhibited the highest adsorption capacity for phenol and methylene blue, and the equilibrium adsorption capacity was 169.0 mg·g-1 and 499.3 mg·g-1, respectively. By comparing the adsorption capacity of various adsorbents in related fields, it is proved that the nitrogen-doped biochar prepared in this study has a good adsorption effect.
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- 2020
3. Nitrogen-Rich D-π-A Structural Carbon Quantum Dots with a Bright Two-Photon Fluorescence for Deep-Tissue Imaging
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Jia Zhu, Yiran Zhang, Jiangbing Zhou, Louzhen Fan, Xiaohong Li, Fanglong Yuan, Shixin Zhou, and Yunchao Li
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Materials science ,business.industry ,Biochemistry (medical) ,Biomedical Engineering ,Absorption cross section ,Deep tissue imaging ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Two photon fluorescence ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,Biomaterials ,Nitrogen rich ,Two-photon excitation microscopy ,Carbon quantum dots ,Optoelectronics ,Spatiotemporal resolution ,0210 nano-technology ,business - Abstract
Two-photon fluorescent (TPF) probes, which allow imaging of biological events in a high spatiotemporal resolution, are in great demand. Recently, carbon quantum dots (CQDs) have emerged as a promising class of TPF probes. Unfortunately, the use of the existing CQDs has been limited by their weak TPF capacities. Herein, we report the first facile and large-scale synthesis of nitrogen-rich CQDs (NRCQDs) based on a donor-π-acceptor (D-π-A) strategy. The resulting NRCQDs demonstrated a tremendous TPF capacity with a two-photon absorption cross section (TPACS) and quantum yield (QY) up to 61 200 Göppert-Mayer (GM) units and 63%, respectively, which is greater than those that could be achieved by the existing TPF carbon probes. Structural and optical analyses of NRCQDs revealed that the great TPF capacity is contributed by the nitrogen-rich D-π-A structure as well as the high crystallinity, large plane, rigid, graphitic nitrogen-doped π-conjugated system. We further demonstrated that NRCQDs allow imaging of live cells as well as live liver tissues at depths of up to 440 μm. Our results suggest NRCQDs as a robust TPF probe that can be potentially used for a variety of biological applications.
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- 2022
4. Red-Emissive Carbon Quantum Dots for Nuclear Drug Delivery in Cancer Stem Cells
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Yang Zhang, Louzhen Fan, Xiaohong Li, Yunchao Li, Shixin Zhou, Wen Su, Fanglong Yuan, and Ruihua Guo
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Cell Survival ,Transplantation, Heterologous ,Mice, Nude ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,HeLa ,Mice ,Cancer stem cell ,Neoplasms ,Quantum Dots ,medicine ,Animals ,Humans ,General Materials Science ,Doxorubicin ,Viability assay ,Physical and Theoretical Chemistry ,Cell Nucleus ,Drug Carriers ,Microscopy, Confocal ,biology ,Chemistry ,021001 nanoscience & nanotechnology ,biology.organism_classification ,Carbon ,0104 chemical sciences ,Transplantation ,Drug delivery ,Cancer cell ,Neoplastic Stem Cells ,Cancer research ,0210 nano-technology ,HeLa Cells ,medicine.drug - Abstract
Large doses of anticancer drugs entering cancer cell nuclei are found to be effective at killing cancer cells and increasing chemotherapeutic effectiveness. Here we report red-emissive carbon quantum dots, which can enter into the nuclei of not only cancer cells but also cancer stem cells. After doxorubicin was loaded at the concentration of 30 μg/mL on the surfaces of carbon quantum dots, the average cell viability of HeLa cells was decreased to only 21%, while it was decreased to 50% for free doxorubicin. The doxorubicin-loaded carbon quantum dots also exhibited a good therapeutic effect by eliminating cancer stem cells. This work provides a potential strategy for developing carbon quantum-dot-based anticancer drug carriers for effective eradication of cancers.
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- 2020
5. Colloidal CdxM1–xTe Nanowires from the Visible to the Near Infrared Region: N,N-Dimethylformamide-Mediated Precise Cation Exchange
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Sheng Huang, Xiaoli Zhang, Jiatao Zhang, Haizheng Zhong, Yunchao Li, Zahid Nazir, Yu Chen, and Dong Li
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Materials science ,Band gap ,business.industry ,Nanowire ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Toluene ,0104 chemical sciences ,Nanomaterials ,Ion ,Solvent ,Colloid ,chemistry.chemical_compound ,Semiconductor ,chemistry ,Physical chemistry ,General Materials Science ,Physical and Theoretical Chemistry ,0210 nano-technology ,business - Abstract
Cation exchange has been a successful methodology for tuning the bandgaps of nanomaterials, while the most popular protocol in the toluene/methanol system lacks precise compositional control due to its inherent poor solvent compatibility. We herein report an alternative cation exchange route in N,N-dimethylformamide (DMF) solvent for converting preformed colloidal CdTe nanowires into CdxM1-xTe (M = Pb2+, Zn2+, Ag+, Hg2+) nanowires with good batch-to-batch reproducibility. The resulting CdxM1-xTe nanowires show a tunable bandgap from 2.26 to 0.63 eV, and the energy levels of these nanowires can be finely tuned. Furthermore, a comparative study for the cation exchange of CdTe nanowires with Pb2+ ions in toluene/methanol and DMF illustrated that the reduction of Cd2+ extraction and the Pb2+ introduction barrier accounts for precise compositional control. The cation exchange reaction in the DMF phase provides an efficient way to obtain nanomaterials with precise composition control. Moreover, these available high-quality colloidal semiconductor nanowires also pave the way for near-infrared device exploration.
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- 2019
6. Biomass derived N-doped biochar as efficient catalyst supports for CO2 methanation
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Kaige Wang, Shurong Wang, Lingjun Zhu, Yunchao Li, Prasert Reubroycharoen, Nakorn Tippayawong, Xiaoliu Wang, Yingying Liu, Pruk Aggarangsi, and Qiu Kunzan
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Process Chemistry and Technology ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Nitrogen ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,Methanation ,Biochar ,Urea ,Chemical Engineering (miscellaneous) ,0210 nano-technology ,Selectivity ,Waste Management and Disposal ,Pyrolysis ,Nuclear chemistry ,Space velocity - Abstract
N-doped biochar with a high nitrogen content and tuned pore structure was obtained from Pinus sylvestris by an in-situ pyrolysis process with simultaneous doping nitrogen and activation where urea was used as a nitrogen precursor and NaHCO3 was employed as the activator. To test the feasibility of N-doped biochars obtained under different pyrolysis temperatures as catalyst supports, a series of Ru catalysts were prepared for use in the methanation and the catalysts were labelled as Ru/N-ABC-x, where x represented the pretreatment temperatures(500, 600 and 700 °C). Besides, the catalytic test of Ru/ABC which was prepared under the same conditions without N modification was also conducted for comparison. The probe reaction test of CO2 methanation showed that the Ru/N-ABC-600 catalyst with the highest pyridinic-N (37.7%) content had superior or comparable catalytic performance to Ru/N-ABC-500 and Ru/N-ABC-700 prepared from N-doped biochar with different pyridinic-N content. A high CO2 conversion of 93.8% with a CH4 selectivity of 99.7% was achieved on Ru/N-ABC-600 under the optimum reaction conditions (380 °C, 1 MPa, n(H2)/n(CO2) of 4, with a gas hourly space velocity of 6000 mL·g-1·h-1). This work provides an effective strategy for the utilization of biochar to develop highly active catalysts for CO2 methanation.
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- 2019
7. Glucose oxidase decorated fluorescent metal-organic frameworks as biomimetic cascade nanozymes for glucose detection through the inner filter effect
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Yunchao Li, Louzhen Fan, Xiaohong Li, Mincong Yu, Wenjie Jing, Fanbo Kong, and Sijia Tian
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02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,Glucose Oxidase ,Biomimetics ,Specific surface area ,Electrochemistry ,Environmental Chemistry ,Humans ,Glucose oxidase ,Spectroscopy ,Metal-Organic Frameworks ,Detection limit ,biology ,Chemistry ,Substrate (chemistry) ,Hydrogen Peroxide ,021001 nanoscience & nanotechnology ,Fluorescence ,Combinatorial chemistry ,0104 chemical sciences ,Glucose ,Linear range ,biology.protein ,Metal-organic framework ,0210 nano-technology ,Selectivity - Abstract
Metal-organic frameworks (MOFs) as a peroxidase mimic have been integrated with glucose oxidase (GOx) to achieve one-step glucose detection. However, limited by the loading amount of GOx, the performances of the developed glucose sensing assays still remain to be further improved to meet sensing requirements in diverse biological samples. Herein, with Fe3+ as the metal ion and 2-amino-benzenedicarboxylic acid as a ligand, a fluorescent Fe-based organic framework (NH2-MIL-101) with peroxidase-like activity was synthesized. Due to the large specific surface area (791.75 m2 g-1), 68 μg mg-1 GOx could be immobilized through the amidation coupling reaction, and the product was designated GOx@NH2-MIL-101. With OPD as the substrate, Gox@NH2-MIL-101 achieved highly efficient biomimetic cascade catalysis for one-step glucose detection through an inner filter effect: upon reacting with glucose, GOx@NH2-MIL-101 catalytically oxidized glucose using dissolved O2, and the produced H2O2 concurrently oxidized o-phenylenediamine (OPD) to oxidized OPD (oxOPD), accompanied by the fluorescence of GOx@NH2-MIL-101 at 456 nm being quenched and that of oxOPD at 565 nm being enhanced. With the fluorescent ratio F565/F456 used as a readout signal, a wide linear range of 0.1-600 μM was obtained, and the detection limit was 0.0428 μM. Based on the excellent selectivity and high stability of GOx@NH2-MIL-101, the developed assay was successfully applied to glucose detection in human serum and saliva, presenting potential applications in diverse biological samples and even medical diagnosis.
- Published
- 2021
8. Ag@SiO2 nanoparticles performing as a nanoprobe for selective analysis of 2-aminoanthracene in wastewater samples via metal-enhanced fluorescence
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Xiaohong Li, Louzhen Fan, Yue Zhang, Yunchao Li, Tian Jin, Yilei Li, and Wenjie Jing
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Detection limit ,Chemistry ,Metal ions in aqueous solution ,010401 analytical chemistry ,Nanoparticle ,Nanoprobe ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,Analytical Chemistry ,Linear range ,Surface plasmon resonance ,0210 nano-technology ,Selectivity - Abstract
Due to severely overlapping emission and or/ excitation spectra of polycyclic aromatic hydrocarbons (PAHs), the specifically recognizing PAHs by the fluorescent technique is still a challenge. Here, synthesized Ag@SiO2 nanoparticles with 40 ± 4 nm Ag core and 7 ± 1 nm SiO2 shell performing as a nanoprobe could selectively recognize 2-aminoanthracene (2-AA) via metal-enhanced fluorescence (MEF) within 2 min. The sensing mechanism was based on the facts: (1) there was a perfect spectral overlap between the local surface plasmon resonance (LSPR) peak of Ag@SiO2 and the absorptive peak of 2-AA, and (2) 2-AA could interact with Ag@SiO2 nanoparticles through hydrogen bonds between –NH2 in 2-AA and –OH in SiO2 shell. As a result, with Ag@SiO2 nanoparticles as a nanoprobe, a fluorescent assay for detecting 2-AA was developed with a linear range from 1 nM to 800 nM, which exhibited an excellent selectivity over possible PAHs, dyes and metal ions. The detection limit was 1 nM. Finally, the developed assay was applied to analyse 2-AA in industrial wastewater samples, which were highly consistent with that of high performance liquid chromatography (HPLC). This study presents a feasible assay for detecting 2-AA for environmental monitoring and toxic evaluating.
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- 2019
9. Highly efficient and stable white LEDs based on pure red narrow bandwidth emission triangular carbon quantum dots for wide-color gamut backlight displays
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Fanglong Yuan, Xiaohong Li, Haizheng Zhong, Yunchao Li, Louzhen Fan, Ping He, Shihe Yang, and Zifan Xi
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Materials science ,Photoluminescence ,business.industry ,02 engineering and technology ,Backlight ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,law.invention ,Full width at half maximum ,Gamut ,Quantum dot ,law ,Optoelectronics ,General Materials Science ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,Electrical efficiency ,Light-emitting diode ,Diode - Abstract
High-performance white light-emitting diodes (WLEDs) hold great potential for the next-generation backlight display applications. However, achieving highly efficient and stable WLEDs with wide-color-gamut has remained a formidable goal. Reported here is the first example of pure red narrow bandwidth emission triangular CQDs (PR-NBE-T-CQDs) with photoluminescence peaking at 610 nm. The PR-NBE-T-CQDs synthesized from resorcinol show high quantum yield (QY) of 72% with small full width at half maximum of 33 nm. By simply controlling the reaction time, pure green (PG-) NBE-T-CQDs with high QY of 75% were also obtained. Highly efficient and stable WLEDs with wide-color-gamut based on PR- and PG-NBE-T-CQDs was achieved. This WLED showed a remarkable wide-color gamut of 110% NTSC and high power efficiency of 86.5 lumens per Watt. Furthermore, such WLEDs demonstrate outstanding stability. This work will set the stage for developing highly efficient, low cost and environment-friendly WLEDs based on CQDs for the next-generation wide-color gamut backlight displays.
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- 2019
10. Bis(trimethylsilyl) 2-fluoromalonate derivatives as electrolyte additives for high voltage lithium ion batteries
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Yunchao Li, Xiao-Guang Sun, Albina Y. Borisevich, Craig A. Bridges, Harry M. Meyer, Charl J. Jafta, Mariappan Parans Paranthaman, Hailong Lyu, and Sheng Dai
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Materials science ,Trimethylsilyl ,Renewable Energy, Sustainability and the Environment ,Scanning electron microscope ,Inorganic chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Malonate ,chemistry ,Electrode ,Lithium ,Graphite ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,0210 nano-technology ,Ethylene carbonate - Abstract
Three trimethylsilyl based malonate esters, bis(trimethylsilyl) 2-methyl-2-fluoromalonate (BTMSMFM), bis(trimethylsilyl) 2-ethyl-2-fluoromalonate (BTMSEFM) and bis(trimethylsilyl) 2-propyl-2-fluoromalonate (BTMSPFM), have been used as additives in 1.0 M LiPF6/ethylene carbonate (EC)-dimethyl carbonate (DMC)-diethyl carbonate (DEC) (1-1-1, by v) baseline electrolyte for LiNi0.80Co0.15Al0.05O2 (NCA) based high voltage lithium ion batteries. The NCA half-cells with 5 wt% BTMSMFM exhibit higher capacity retention than that in the baseline electrolyte at different upper cut off voltages, that is, 4.2, 4.3, 4.4 and 4.5 V vs. Li/Li+. Scanning electron microscope (SEM) show that the additive successfully prevents the formation of thick solid electrolyte interphase (SEI) films on the surface of the NCA electrodes. X-ray diffraction (XRD) further reveals that the crystal structure of NCA is also maintained in the electrolyte with 5 wt% BTMSMFM at high cut off voltages. Besides beneficial to NCA cathode, the BTMSMFM additive also ensures better cycling performance of the graphite based half-cells and NCA/graphite full-cells, and thus is a promising additive for application in rechargeable lithium ion batteries.
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- 2019
11. Thioflavin T specifically brightening 'Guanine Island' in duplex-DNA: a novel fluorescent probe for single-nucleotide mutation
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Tian Jin, Yunchao Li, Wei Zhou, Xiaohong Li, Ze Yu, Louzhen Fan, and Ge Ma
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Guanine ,Stereochemistry ,Stacking ,02 engineering and technology ,medicine.disease_cause ,Polymorphism, Single Nucleotide ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,chemistry.chemical_compound ,Electrochemistry ,medicine ,Environmental Chemistry ,A-DNA ,Benzothiazoles ,Spectroscopy ,Fluorescent Dyes ,Mutation ,Base Sequence ,Hydrogen bond ,010401 analytical chemistry ,DNA ,Mercury ,021001 nanoscience & nanotechnology ,Fluorescence ,0104 chemical sciences ,chemistry ,Thioflavin ,0210 nano-technology - Abstract
Here, we found that Thioflavin T (ThT) could specifically bind with a G-GGG unit (named as "Guanine Island") in double stranded DNA (ds-DNA). Through stacking with G base via hydrogen bonds, the rotation of ThT was restricted and concurrently its planarization was enforced. Such a binding mode produced a significantly enhanced ThT fluorescence. Based on this discovery, with ThT as a lighting-up probe for "Guanine Island" in ds-DNA, the fluorescent detection of single-nucleotide mutation (C mutation) was investigated. With C base in target DNA mutating to G, A or T and further hybridizing with a probe DNA containing a GGG unit at the mutated point, ds-DNA including G-GGG, A-GGG or T-GGG islands was formed, respectively. After binding with ThT, C mutation was clearly recognized. With C mutating to G as an example, the detection limit was as low as 3 nM. Importantly, the developed assay could be applied to recognize C mutating to G in a DNA sequence related to dilated cardiomyopathy for diluted human serum. As a sensing unit ("Guanine Island" in ds-DNA lighting up ThT), it is expected to be applied for various biological or environmental systems.
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- 2019
12. Carbon quantum dots: an emerging material for optoelectronic applications
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Yunchao Li, Ting Yuan, Xiaohong Li, Yuxin Shi, Louzhen Fan, Shihe Yang, Ting Meng, and Ping He
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Materials science ,business.industry ,Photodetector ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Nanomaterials ,Carbon quantum dots ,Materials Chemistry ,Optoelectronics ,0210 nano-technology ,business ,Phosphorescence ,Lasing threshold - Abstract
As an emerging class of luminescent nanomaterials, carbon quantum dots (CQDs) have recently shown enormous potential for optoelectronic applications on account of their characteristic broad emission, tunable fluorescence emission, high thermal stability, and low cytotoxicity. In this review, we will update the latest research progress achieved in CQDs, including their synthesis, optical properties, luminescence mechanism, and applications in optoelectronics. Mainly reviewed here are their room temperature phosphorescence, delayed fluorescence properties, as well as their optoelectronic applications including light-emitting diodes, lasing, solar cells, and photodetectors. Finally, current problems and challenges of CQD-based optoelectronics applications are discussed with an eye on future development. We hope that this review will provide critical insights to inspire new exciting discoveries in the area of CQDs from both fundamental and practical standpoints so that the realization of their potential in the optoelectronic areas can be facilitated.
- Published
- 2019
13. A colorimetric immuno-microarray for the quantitation and direct visualization of illicit drugs in body fluids
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Lingling Zhang, Xiaochun Li, Hua-Zhong Yu, and Yunchao Li
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Analyte ,Microarray ,02 engineering and technology ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,Lab-On-A-Chip Devices ,Electrochemistry ,Environmental Chemistry ,Humans ,Spectroscopy ,Volume concentration ,Detection limit ,Immunoassay ,Chromatography ,Chemistry ,Illicit Drugs ,010401 analytical chemistry ,021001 nanoscience & nanotechnology ,16. Peace & justice ,0104 chemical sciences ,Body Fluids ,Visual recognition ,Competitive immunoassay ,Colorimetry ,0210 nano-technology - Abstract
The design and testing of integrated colorimetric microarray immunochips (immuno-microarrays) are reported for the quantitation and direct visual determination of multiple illicit drugs (e.g., morphine, cocaine and amphetamine) in body fluids. Such an immuno-microarray platform utilizes a competitive immunoassay format, which is based on silver staining for quantitative detection and multicolor staining for direct visualization (i.e., qualitative identification) of analytes present in the sample. Under optimized conditions, the dynamic response ranges of 3.7–1000, 1.1–300 and 1.5–300 ng mL−1 were achieved for amphetamine, cocaine, and morphine, respectively, which are wider towards low concentrations than those of standard enzyme-linked immunosorbent assay (ELISA) tests. The limits of detection (LODs) for morphine, cocaine, and amphetamine were determined to be 1.5 ± 0.1, 1.1 ± 0.1 and 3.7 ± 0.2 ng mL−1, respectively in oral fluids, which meet government regulations for law enforcement. The obvious advantages of multiplexing, simultaneous visual recognition, and accurate quantitation make the on-site detection feasible, confirming that such a colorimetric immuno-microarray holds promise for practical applications.
- Published
- 2020
14. Fe-N/C single-atom nanozyme-based colorimetric sensor array for discriminating multiple biological antioxidants
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Louzhen Fan, Yunchao Li, Xiaohong Li, Fanbo Kong, Xiangkun Cui, Wenjie Jing, and Wei Wei
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Antioxidant ,medicine.medical_treatment ,02 engineering and technology ,Ascorbic Acid ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Colorimetry (chemical method) ,Antioxidants ,Analytical Chemistry ,chemistry.chemical_compound ,Sensor array ,Electrochemistry ,medicine ,Environmental Chemistry ,Humans ,Spectroscopy ,Chromatography ,ABTS ,Glutathione ,Buffer solution ,021001 nanoscience & nanotechnology ,Ascorbic acid ,0104 chemical sciences ,chemistry ,Uric acid ,Colorimetry ,0210 nano-technology ,Oxidation-Reduction - Abstract
Identifying the species and concentrations of antioxidants is really important because antioxidants play important roles in various biological processes and numerous diseases. Compared with an individual sensor detecting a single antioxidant with limited specificity, a sensor array could simultaneously identify various antioxidants, in which 3-5 types of nanomaterials with peroxidase-like activity are absolutely necessary. Herein, as a single-atom nanozyme, Fe-N/C with oxidase-mimicking activity was applied to construct a triple-channel colorimetric sensor array: (1) Fe-N/C catalytically oxidized three substrates 3,3',5,5'-tetramethylbenzidine (TMB), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and o-phenylenediamine (OPD) to produce blue oxidized TMB (oxTMB), green oxidized ABTS (oxABTS) and yellow oxidized OPD (oxOPD), respectively; (2) with oxTMB, oxABTS and oxOPD as three sensing channels, a colorimetric sensor array was constructed for simultaneously discriminating glutathione (GSH), l-cysteine (l-Cys), ascorbic acid (AA), uric acid (UA), and melatonin (MT), even quantifying concentrations (with GSH as a model analyst). The performance of the sensor array was validated through accurately identifying 15 blind samples containing GSH, l-Cys, AA, UA and MT in buffer solution and human serum samples, and also in binary and ternary mixtures. This work proved that fabricating a single nanozyme-based sensor array was a simplified and reliable strategy for simultaneously probing multiple antioxidants.
- Published
- 2020
15. Insights into the Competition between K+ and Pb2+ Binding to a G-Quadruplex and Discovery of a Novel K+–Pb2+–Quadruplex Intermediate
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Yi Lu, Xiaohong Li, Ze Yu, Yunchao Li, Wei Zhou, Ge Ma, and Louzhen Fan
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Chemistry ,Stereochemistry ,media_common.quotation_subject ,010401 analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,G-quadruplex ,01 natural sciences ,Competition (biology) ,0104 chemical sciences ,Surfaces, Coatings and Films ,Materials Chemistry ,heterocyclic compounds ,sense organs ,Physical and Theoretical Chemistry ,skin and connective tissue diseases ,0210 nano-technology ,media_common - Abstract
Numerous studies have reported cation-dependent stability and topological changes of G-quadruplexes (G4s), but competitions between cations at different concentrations for binding with G4s and thei...
- Published
- 2018
16. Tire-derived carbon for catalytic preparation of biofuels from feedstocks containing free fatty acids
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Zachary D. Hood, Miaofang Chi, Abdou Lachgar, Hui Wang, Samuel F. Evans, Yunchao Li, M. Parans Paranthaman, Shiba P. Adhikari, and Amit K. Naskar
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Materials Science (miscellaneous) ,Sonication ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,lcsh:Chemical technology ,01 natural sciences ,complex mixtures ,Catalysis ,medicine ,Organic chemistry ,lcsh:TP1-1185 ,chemistry.chemical_classification ,Process Chemistry and Technology ,fungi ,Fatty acid ,Microporous material ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Fuel Technology ,chemistry ,Biofuel ,Yield (chemistry) ,Ferric ,lipids (amino acids, peptides, and proteins) ,0210 nano-technology ,Carbon ,medicine.drug - Abstract
The utilization of waste feedstocks rich in free fatty acids (FFAs) improves biofuel production on the basis of economics and sustainability. However, converting these feedstocks to usable biofuel poses inherent problems in terms of the FFA to biofuel conversion yield and the catalyst lifetime. Here, we report novel ferric sulfate impregnated carbon derived from waste tires as highly active catalysts for FFA to biofuel conversion. Our approach takes advantage of facile synthesis methods involving sonication and dehydration processes to create materials that are useful for the efficient catalytic conversion of FFAs to advanced biofuels. Esterification of FFAs to fatty acid methyl esters was achieved at 65 °C and atmospheric pressure with >98% yield even in the presence of triglycerides. These catalysts maintained similar activity after four successive uses, which indicates that the active catalytic sites are effectively supported by the three-dimensional meso/microporous architecture of the tire-derived carbon. Keywords: Biofuels, Solid acid catalyst, Recycled tires, Free fatty acids, Esterification
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- 2018
17. Engineering triangular carbon quantum dots with unprecedented narrow bandwidth emission for multicolored LEDs
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Louzhen Fan, Zifan Xi, Mingxing Jin, Anmin Chen, Fanglong Yuan, Shihe Yang, Zhibin Wang, Xiaohong Li, Ting Yuan, Laizhi Sui, Zhan'ao Tan, and Yunchao Li
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Materials science ,Science ,General Physics and Astronomy ,chemistry.chemical_element ,Quantum yield ,02 engineering and technology ,Astrophysics::Cosmology and Extragalactic Astrophysics ,010402 general chemistry ,01 natural sciences ,Luminance ,General Biochemistry, Genetics and Molecular Biology ,Article ,Narrow bandwidth ,law.invention ,law ,lcsh:Science ,Astrophysics::Galaxy Astrophysics ,Diode ,Multidisciplinary ,business.industry ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,0104 chemical sciences ,Full width at half maximum ,chemistry ,Carbon quantum dots ,Optoelectronics ,lcsh:Q ,0210 nano-technology ,business ,Carbon ,Light-emitting diode - Abstract
Carbon quantum dots (CQDs) have emerged as promising materials for optoelectronic applications on account of carbon’s intrinsic merits of high stability, low cost, and environment-friendliness. However, the CQDs usually give broad emission with full width at half maximum exceeding 80 nm, which fundamentally limit their display applications. Here we demonstrate multicolored narrow bandwidth emission (full width at half maximum of 30 nm) from triangular CQDs with a quantum yield up to 54–72%. Detailed structural and optical characterizations together with theoretical calculations reveal that the molecular purity and crystalline perfection of the triangular CQDs are key to the high color-purity. Moreover, multicolored light-emitting diodes based on these CQDs display good stability, high color-purity, and high-performance with maximum luminance of 1882–4762 cd m−2 and current efficiency of 1.22–5.11 cd A−1. This work will set the stage for developing next-generation high-performance CQDs-based light-emitting diodes., Carbon quantum dots have promising advantages such as high stability, low cost and environment-friendliness, but their broad emission band limits their application in displays. Here Yuan et al. synthesize these dots showing tunable emission color, high fluorescence and a narrow FWHM of only 30 nanometers.
- Published
- 2018
18. Precursor reactivity differentiation for single-step preparation of Ag2Se@Ag2S core–shell nanocrystals with distinct absorption and emission properties enabling sensitive near-infrared photodetection
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Cai Wenhao, Shilin Tang, Chuansheng He, Dong Li, Louzhen Fan, and Yunchao Li
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Materials science ,Mechanical Engineering ,Quantum yield ,02 engineering and technology ,Photodetection ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,Nanomaterials ,Full width at half maximum ,Nanocrystal ,Mechanics of Materials ,General Materials Science ,Reactivity (chemistry) ,0210 nano-technology ,Absorption (electromagnetic radiation) - Abstract
To obtain dual active near-infrared (NIR) nanomaterial with strong absorption and emission properties, we report herein a novel precursor reactivity differentiation strategy, i.e., utilizing 1-octadecene (ODE)–Se having the ability to react with Ag salts much stronger and faster than ODE–thiourea, for single-step preparation of Ag2Se@Ag2S nanocrystals (NCs). With this strategy, we were able to synthesize high-quality Ag2Se@Ag2S NCs with both excellent NIR absorption and emission properties. Particularly, these nanocrystals possess a rather strong and sharp excitonic absorption peak with a full width at half maximum less than 70 nm and a maximum fluorescence quantum yield as high as 24.3%. Their appealing optical properties and structural features were founded to be highly dependent on the Se to S precursor ratio in the reaction solutions, owing to such a ratio exerting a direct influence on the core sizes and shell thicknesses of the as-formed NCs. Taking advantage of their remarkable NIR absorption properties, self-powered photoelectrochemical-type photodetectors based on the as-prepared Ag2Se@Ag2S NCs were successfully fabricated, which demonstrate a much better response performance and photostability in comparison with those based on Ag2Se NCs.
- Published
- 2018
19. Carbon/tin oxide composite electrodes for improved lithium-ion batteries
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Amit K. Naskar, M. Parans Paranthaman, Richard J. Lee, Alan M. Levine, Sheng Dai, Yunchao Li, and Jinshui Zhang
- Subjects
Battery (electricity) ,Materials science ,General Chemical Engineering ,Oxide ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Tin oxide ,01 natural sciences ,0104 chemical sciences ,Anode ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Materials Chemistry ,Electrochemistry ,Lithium ,0210 nano-technology ,Tin ,Carbon ,Ball mill - Abstract
Tin and tin oxide-based electrodes are promising high-capacity anodes for lithium-ion batteries. However, poor capacity retention is the major issue with these materials due to the large volumetric expansion that occurs when lithium is alloyed with tin during lithiation and delithiation process. Here, a method to prepare a low-cost, scalable carbon and tin(II) oxide composite anode is reported. The composite material was prepared by ball milling of carbon recovered from used tire powders with 25 wt% tin(II) oxide to form lithium-ion battery anode. With the impact of energy from the ball milling, tin oxide powders were uniformly distributed inside the pores of waste-tire-derived carbon. During lithiation and delithiation, the carbon matrix can effectively absorb the volume expansion caused by tin, thereby minimizing pulverization and capacity fade of the electrodes. The as-synthesized anode yielded a capacity of 690 mAh g−1 after 300 cycles at a current density of 40 mA g−1 with a stable battery performance. A method to prepare low-cost carbon/tin (II) oxide (SnO) composite by ball milling is reported. SnO powders are uniformly distributed inside the carbon matrix, which could effectively absorb the volume expansion of Sn and alleviate capacity fade. The anode yields a capacity of 690 mAh g−1 after 300 cycles.
- Published
- 2018
20. K+ Concentration-Dependent Conformational Change of Pb2+-Stabilized G-quadruplex
- Author
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北京师范大学化学学院,北京, Xiaohong Li, Ze Yu, Yunchao Li, Mingfu Ye, and 安徽工业大学化学与化工学院,安徽 马鞍山
- Subjects
Crystallography ,Conformational change ,Chemistry ,010401 analytical chemistry ,02 engineering and technology ,K concentration ,Physical and Theoretical Chemistry ,021001 nanoscience & nanotechnology ,0210 nano-technology ,G-quadruplex ,01 natural sciences ,0104 chemical sciences - Published
- 2018
21. Conversion of Waste Tire Rubber into High-Value-Added Carbon Supports for Electrocatalysis
- Author
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Amit K. Naskar, Mariappan Parans Paranthaman, Miaofang Chi, Xuan Yang, Zachary D. Hood, and Yunchao Li
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Electrocatalyst ,Pulp and paper industry ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Natural rubber ,chemistry ,visual_art ,Value (economics) ,Materials Chemistry ,Electrochemistry ,visual_art.visual_art_medium ,0210 nano-technology ,Carbon - Published
- 2018
22. Quantitative comparison of three representative staining methods for the development of multichannel colorimetric biochips
- Author
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Xiaoyi Gao, Hua-Zhong Yu, Mingxi Geng, Yunchao Li, and Jiale He
- Subjects
Chromatography ,biology ,medicine.diagnostic_test ,General Chemical Engineering ,010401 analytical chemistry ,General Engineering ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Horseradish peroxidase ,0104 chemical sciences ,Analytical Chemistry ,Staining ,Silver stain ,chemistry.chemical_compound ,chemistry ,Immunoassay ,biology.protein ,medicine ,Alkaline phosphatase ,Multiple tumors ,Formazan ,0210 nano-technology ,Biochip - Abstract
Assay staining is an essential step to produce visual signals for the development of colorimetric biochips; it is, therefore, of practical importance to evaluate the conventionally adopted staining methods in terms of their quantitative performance in screening immunoassay biochips. Particularly, we have performed a systematic comparison of the color development speed, sensitivity, response range, and aging effects of three common staining protocols, i.e., gold nanoparticle-catalyzed silver deposition (silver staining), horseradish peroxidase (HRP)-catalyzed oxidation of tetramethylbenzidine (TMB staining), and alkaline phosphatase (ALP)-catalyzed reduction of tetrazolium salt (TAS staining). Our results have revealed that silver staining can afford the best screening performance in terms of sensitivity, response range, and aging effect. In comparison, TMB staining is fast in producing quantitative results (5–10 min). TAS staining can provide easily saturated signals with a low background, which is suitable for semi-quantitative or qualitative on-site applications. More importantly, we have demonstrated that the three staining methods can be adapted to the same biochip to fabricate “multichannel” colorimetric biochips for screening multiple tumor markers simultaneously.
- Published
- 2018
23. Lithium malonatoborate additives enabled stable cycling of 5 V lithium metal and lithium ion batteries
- Author
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Sheng Dai, Gabriel M. Veith, Xiao-Guang Sun, Mariappan Parans Paranthaman, Dale K. Hensley, Yunchao Li, Katie L. Browning, and Jihua Chen
- Subjects
Materials science ,Passivation ,Renewable Energy, Sustainability and the Environment ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,Corrosion ,chemistry.chemical_compound ,chemistry ,Electrode ,General Materials Science ,Lithium ,Graphite ,Electrical and Electronic Engineering ,0210 nano-technology ,Ethylene carbonate - Abstract
A series of lithium difluoro-2-fluoro-2-alkyl-malonatoborate salts have been used as additives in conventional 1.0 M LiPF6/ethylene carbonate (EC)-dimethyl carbonate (DMC)-diethyl carbonate (DEC) (1-1-1, by v) electrolyte for high voltage LiNi0.5Mn1.5O4 (LNMO) based lithium metal and lithium ion batteries. Cyclic voltammograms (CVs) reveal that the electrolytes with additives can significantly suppress the co-intercalation of solvents into the graphene layers during the first cycle due to their sacrificial reductions on the surface of the graphite electrode above 1.0 V vs Li/Li+. In addition, CVs reveal that the electrolyte without additive suffers from extensive electrolyte oxidation on the surface of the LNMO electrode during the first cycle, resulting in the biggest increase of the total cell impedance. Furthermore, electrochemical floating test shows less oxidation current in the electrolytes with additives at voltages above 5.0 V, proving good passivation by the additives. More importantly, the presence of additives can effectively increase the first cycle coulombic efficiencies and cycling stability in the LNMO based lithium metal and lithium ion batteries. Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) show that with additives compact solid electrolyte interphase (SEI) and thinner passivation layer are formed on the surfaces of the graphite and LNMO electrode, respectively. Finally, these salt additives can better protect the current collector from corrosion, further confirming their effectiveness in conventional electrolytes for high-voltage lithium metal and lithium ion batteries.
- Published
- 2017
24. Novel Acid Catalysts from Waste‐Tire‐Derived Carbon: Application in Waste–to‐Biofuel Conversion
- Author
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Miaofang Chi, Yunchao Li, Zachary D. Hood, Amit K. Naskar, M. Parans Paranthaman, Legna Figueroa-Cosme, Shiba P. Adhikari, Younan Xia, Abdou Lachgar, and Marcus W. Wright
- Subjects
chemistry.chemical_classification ,Materials science ,food.ingredient ,chemistry.chemical_element ,Sulfuric acid ,02 engineering and technology ,General Chemistry ,Sulfonic acid ,010402 general chemistry ,021001 nanoscience & nanotechnology ,complex mixtures ,01 natural sciences ,Soybean oil ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Oleic acid ,food ,chemistry ,Leaching (chemistry) ,Biofuel ,Organic chemistry ,0210 nano-technology ,Carbon - Abstract
Many inexpensive biofuel feedstocks, including those containing free fatty acids (FFAs) in high concentrations, are typically disposed of as waste due to our inability to efficiently convert them into usable biofuels. Here we demonstrate that carbon derived from waste tires could be functionalized with sulfonic acid (-SO3H) to effectively catalyze the esterification of oleic acid or a mixture of fatty acids to usable biofuels. Waste tires were converted to hard carbon, then functionalized with catalytically active -SO3H groups on the surface through an environmentally benign process that involved the sequential treatment with L-cysteine, dithiothreitol, and H2O2. When benchmarked against the same waste-tire derived carbon material treated with concentrated sulfuric acid at 150 °C, similar catalytic activity was observed. Both catalysts could also effectively convert oleic acid or a mixture of fatty acids and soybean oil to usable biofuels at 65 °C and 1 atm without leaching of the catalytic sites.
- Published
- 2017
25. Sustainable Potassium-Ion Battery Anodes Derived from Waste-Tire Rubber
- Author
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Ryan A. Adams, Anjela Arora, Kokouvi Akato, Vilas G. Pol, Richard J. Lee, Amit K. Naskar, Yunchao Li, Mariappan Parans Paranthaman, and Alan M. Levine
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,Metallurgy ,Potassium-ion battery ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Anode ,Natural rubber ,visual_art ,Materials Chemistry ,Electrochemistry ,visual_art.visual_art_medium ,0210 nano-technology - Published
- 2017
26. Systematic truncating of aptamers to create high-performance graphene oxide (GO)-based aptasensors for the multiplex detection of mycotoxins
- Author
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Xiaochen Hu, Louzhen Fan, Hua-Zhong Yu, Jiale He, Xinglin Wang, Yunchao Li, Xiaoyi Gao, and Xiaohong Li
- Subjects
Aflatoxin B1 ,Aptamer ,Oxide ,Nanotechnology ,02 engineering and technology ,Biosensing Techniques ,01 natural sciences ,Biochemistry ,Rapid detection ,Fluorescence ,Analytical Chemistry ,law.invention ,Single test ,chemistry.chemical_compound ,law ,Limit of Detection ,Electrochemistry ,Environmental Chemistry ,Multiplex ,Spectroscopy ,Fluorescent Dyes ,Detection limit ,Base Sequence ,Chemistry ,Graphene ,010401 analytical chemistry ,DNA ,Aptamers, Nucleotide ,021001 nanoscience & nanotechnology ,Ochratoxins ,0104 chemical sciences ,Nucleic Acid Conformation ,Graphite ,0210 nano-technology ,Target binding - Abstract
Graphene oxide (GO)-based aptasensors are currently one of the most popular sensing platforms for the simple and rapid detection of various targets. Unfortunately, the GO-based aptasensors with long aptamer strands typically show unsatisfactory performance resulting from insignificant structural transformations upon target binding. We report herein the utilization of an aptamer-truncating strategy to combat such a challenge. Taking a pre-selected anti-aflatoxin B1 (AFB1) aptamer (P-AFB1-50) as a trial system, we sequentially remove the extraneous nucleotides within the aptamer by means of circular dichroism (CD) spectroscopy and binding affinity analysis. Particularly, the ratio of the quenching constants between the GO sheets and the truncated aptamers (labelled with fluorophores) in the absence and presence of the target was determined for each of the truncated aptamers to evaluate the optimal sequence. As a result, the truncated aptamer comprising 40 nucleotides was confirmed to show the highest FL output and the best detection limit upon conjugation with GO sheets. More importantly, we demonstrated that this truncating strategy is versatile, i.e., it can be easily extended to other aptamer systems (anti-ochratoxin A (OTA) aptamer, P-OTA-61, as an example) for extraneous nucleotide identification. Impressively, the two optimal truncated aptamers can work together on GO sheets to achieve a simultaneous detection of two different mycotoxins (i.e., AFB1 and OTA) in one single test. Essentially, this research opens a new avenue for the design and testing of aptamer-/GO-based-sensing platforms for rapid, low-cost and multiplex quantification of analytical targets of interest.
- Published
- 2019
27. Electroluminescent Warm White Light‐Emitting Diodes Based on Passivation Enabled Bright Red Bandgap Emission Carbon Quantum Dots
- Author
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Fanglong Yuan, Yunchao Li, Haoran Jia, Louzhen Fan, Xiaohong Li, Zhibin Wang, Zhan'ao Tan, Ting Yuan, and Shihe Yang
- Subjects
Materials science ,Photoluminescence ,Passivation ,Band gap ,General Chemical Engineering ,General Physics and Astronomy ,Medicine (miscellaneous) ,Quantum yield ,02 engineering and technology ,Electroluminescence ,010402 general chemistry ,01 natural sciences ,Biochemistry, Genetics and Molecular Biology (miscellaneous) ,Spectral line ,electroluminescence ,high quantum yield ,General Materials Science ,warm white light‐emitting diodes ,lcsh:Science ,Diode ,Full Paper ,business.industry ,General Engineering ,Full Papers ,021001 nanoscience & nanotechnology ,carbon quantum dots ,0104 chemical sciences ,Excited state ,Optoelectronics ,lcsh:Q ,0210 nano-technology ,business ,red fluorescence - Abstract
The development of efficient red bandgap emission carbon quantum dots (CQDs) for realizing high‐performance electroluminescent warm white light‐emitting diodes (warm‐WLEDs) represents a grand challenge. Here, the synthesis of three red‐emissive electron‐donating group passivated CQDs (R‐EGP‐CQDs): R‐EGP‐CQDs‐NMe2, ‐NEt2, and ‐NPr2 is reported. The R‐EGP‐CQDs, well soluble in common organic solvents, display bright red bandgap emission at 637, 642, and 645 nm, respectively, reaching the highest photoluminescence quantum yield (QY) up to 86.0% in ethanol. Theoretical investigations reveal that the red bandgap emission originates from the rigid π‐conjugated skeleton structure, and the ‐NMe2, ‐NEt2, and ‐NPr2 passivation plays a key role in inducing charge transfer excited state in the π‐conjugated structure to afford the high QY. Solution‐processed electroluminescent warm‐WLEDs based on the R‐EGP‐CQDs‐NMe2, ‐NEt2, and ‐NPr2 display voltage‐stable warm white spectra with a maximum luminance of 5248–5909 cd m−2 and a current efficiency of 3.65–3.85 cd A−1. The warm‐WLEDs also show good long‐term operational stability (L/L 0 > 80% after 50 h operation, L 0: 1000 cd m−2). The electron‐donating group passivation strategy opens a new avenue to realizing efficient red bandgap emission CQDs and developing high‐performance electroluminescent warm‐WLEDs.
- Published
- 2019
28. Diameter- and Length-controlled Synthesis of Ultrathin ZnS Nanowires and Their Size-Dependent UV Absorption Properties, Photocatalytical Activities and Band-Edge Energy Levels
- Author
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Xiaohong Li, Simeng Hao, Guanjie Xing, Louzhen Fan, Xiaoli Liu, and Yunchao Li
- Subjects
Materials science ,General Chemical Engineering ,Exciton ,Nanowire ,02 engineering and technology ,010402 general chemistry ,medicine.disease_cause ,Electrochemistry ,01 natural sciences ,Article ,lcsh:Chemistry ,medicine ,size-controlled synthesis ,General Materials Science ,Absorption (electromagnetic radiation) ,ultrathin semiconductor nanowires ,business.industry ,Thermal decomposition ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Semiconductor ,lcsh:QD1-999 ,size-dependent optoelectronic properties ,Photocatalysis ,Optoelectronics ,0210 nano-technology ,business ,Ultraviolet - Abstract
Benefiting from their ultra-small diameters and highly structural anisotropies, ultrathin semiconductor nanowires (USNWs) are well-known for their fascinating physical/chemical properties, as well as their promising applications in various fields. However, until now, it remains a challenge to synthesize high-quality USNWs with well-controlled diameters and lengths, let alone the exploration of their size-dependent properties and applications. To solve such a challenge, we report herein a ligand-induced low-temperature precursor thermolysis route for the controlled preparation of ultrathin ZnS nanowires, which is based on the oriented assembly of the in-situ formed ZnS clusters/tiny particles. Optimized synthetic conditions allowed the synthesis of ZnS nanowires with a diameter down to 1.0 nm and a length approaching 330 nm. The as-prepared ultrathin ZnS nanowires were then intensively examined by morphological, spectroscopic and electrochemical analytical means to explore their size-dependent optical absorption properties, photocatalytic activities and band-edge energy levels, as well as their underlying growth mechanism. Notably, these USNWs, especially for the thinnest nanowires, were identified to possess an excellent performance in both the selective absorption of ultraviolet (UV) light and photocatalytic degradation of dyes, thus enabling them to serve as longpass ultraviolet filters and high-efficiency photocatalysts, respectively. For the ultrathin ZnS nanowires with a diameter of 1.0 nm, it was also interesting to observe that their exciton absorption peak positions were kept almost unchanged during the continuous extension of their lengths, which has not been reported previously.
- Published
- 2019
29. Effect of Quenching Conditions on the Microstructure and Mechanical Properties of 51CrV4 Spring Steel
- Author
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Lin Zhang, Dehai Gong, Xiaojun Wang, Engang Wang, Xixi Ren, and Yunchao Li
- Subjects
lcsh:TN1-997 ,carbides ,Materials science ,Bainite ,quenching ,51CrV4 ,02 engineering and technology ,01 natural sciences ,Indentation hardness ,Spring steel ,0103 physical sciences ,Ultimate tensile strength ,General Materials Science ,Composite material ,Ductility ,lcsh:Mining engineering. Metallurgy ,010302 applied physics ,Quenching ,Metals and Alloys ,martensite ,021001 nanoscience & nanotechnology ,Microstructure ,hardness ,Martensite ,0210 nano-technology ,strength ,spring steel - Abstract
51CrV4 steel is extensively used in large-size damping springs for trains and vehicles. Quenching conditions play an important role in performance enhancement. The present work investigated the effects of various oil-bath temperatures and out-of-oil temperatures on the microstructure and the mechanical properties of this steel. The morphological examination focused on both the quenched martensite and the tempered troostite. Tensile and hardness tests were carried out to evaluate the mechanical properties. The results showed that a coarsening of the martensite occurred at a high oil-bath temperature. In addition, the size and fraction of bainite islands also increased with the increase of oil-bath temperature. In contrast, the carbide size and the intercarbide spacing both increased with the increase of oil-bath temperature. Thus, the tensile strength and the hardness both decreased with increasing oil-bath temperature in accordance with the Hall-Petch relationship. Correspondingly, the ductility increased as the oil-bath temperature increased. At a relatively high out-of-oil temperature, the martensite underwent an auto-tempering process, which led to the precipitation of many tiny carbide particles in the as-quenched martensite laths. This auto-tempering effect enhanced the width of large-sized carbides and reduced their length in the final microstructure. The intercarbide spacings increased with increasing out-of-oil temperature. As the oil-bath temperature increased, the tensile strength and hardness decreased, and the ductility increased. The fracture morphology was examined to explain the results of mechanical properties.
- Published
- 2018
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30. Controlled synthesis of mesoporous codoped titania nanoparticles and their photocatalytic activity
- Author
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Jinshui Zhang, M. Paranthaman, J. E. Mathis, Yunchao Li, and Michelle K. Kidder
- Subjects
Fluid Flow and Transfer Processes ,Titania nanoparticles ,Anatase ,Materials science ,Mechanical Engineering ,Dispersity ,Nanoparticle ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Catalysis ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Transition metal ,Ceramics and Composites ,Photocatalysis ,Electrical and Electronic Engineering ,0210 nano-technology ,Mesoporous material ,Micro spheres ,Biotechnology - Abstract
The photocatalytic (PC) activity of anatase titania nanoparticles can be improved through codoping with transition metals and nitrogen. In addition, the PC activity can also be improved by creating monodisperse, mesoporous nanoparticles of titania. The question naturally arose as to whether combining these two characteristics would result in further improvement in the PC activity or not. Herein, we describe the synthesis and photocatalytic characteristics of codoped, monodisperse anatase titania. The transition metals tested in the polydisperse and the monodisperse forms were Mn, Co, Ni, and Cu. In each case, it was found that the monodisperse version had a higher PC activity compared to the corresponding polydisperse version.
- Published
- 2016
31. Controlled calcination of ZnSe and ZnTe nanospheres to prepare visible-light catalysts with enhanced photostability and photoactivity
- Author
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Wanting Yang, Xiaohong Li, Xiaoli Liu, Yunchao Li, Dong Li, Shilin Tang, and Louzhen Fan
- Subjects
Materials science ,Mechanical Engineering ,Nanotechnology ,02 engineering and technology ,Crystal structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Catalysis ,law.invention ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Mechanics of Materials ,law ,Photocatalysis ,General Materials Science ,Calcination ,Irradiation ,0210 nano-technology ,Absorption (electromagnetic radiation) ,Methylene blue ,Visible spectrum - Abstract
To obtain cheap, low-toxic, efficient and robust visible-light photocatalyst, a controlled calcination strategy is proposed for converting unstable ZnX (X=Se, Te) nanospheres (NSs) to ZnX–ZnO hybrid nanospheres (HNSs) with an appropriate composition and structure. Under such a conception, ZnSe–ZnO HNSs with various compositions were prepared by calcining ZnSe NSs under different conditions. Their morphology, composition, crystal structure, and optical absorption property were found to be highly dependent on their calcination condition. When serving as the catalyst for photodegrading organic dyes, they exhibited an attractive composition/structure-dependent photocatalytic activity and enhanced photostability. Particularly, the HNSs prepared by calcining at 500 °C for 4.0 h demonstrated the highest photocatalytic activity and excellent photostability, only taking 4.5 and 5.5 h to degrade 97.3 % methylene blue (MB) and 93 % ethyl violet (EV), respectively, under visible irradiation. The reason why such HNSs possessed the best photocatalytic performance was then intensively explored from different points of view. Moreover, we also extended this calcination protocol to prepare ZnTe–ZnO HNSs, whose photocatalytic performance was proven to be much better than that of pure ZnTe NSs as expected. We believe the strategy for fabricating such hybrid nanospheres and the exploration on their excellent photocatalytic performance will definitely benefit the preparation of high-efficient visible-light catalyst as well as the better understanding of its composition/structure-dependent photocatalytic activity.
- Published
- 2016
32. Na+-Induced Conformational Change of Pb2+-Stabilized G-Quadruplex and Its Influence on Pb2+ Detection
- Author
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Yunchao Li, Ze Yu, Louzhen Fan, Xiaohong Li, Wei Zhou, and Juan Han
- Subjects
Conformational change ,Circular dichroism ,Chemistry ,Analytical chemistry ,Native Polyacrylamide Gel Electrophoresis ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Mass spectrometry ,G-quadruplex ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,Analytical Chemistry ,Crystallography ,Desorption ,0210 nano-technology ,Spectroscopy - Abstract
Here, we first find that Na+ can induce Pb2+-stabilized T30695 undergoing conformational transition from partly parallel to completely parallel, and further forming a dimeric G-quadruplex, which was characterized by circular dichroism (CD) spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and native polyacrylamide gel electrophoresis (PAGE). Thermal denaturation experiments show that the transforming process is a thermodynamics-driven process. Furthermore, the presence of Na+ further improves the binding efficiency of Pb2+-stabilized T30695 with the fluorescent probe (such as ZnPPIX). Based on the fact, with a partially hybridized double-stranded DNA (ds-DNA) containing T30695 as a sensing probe and ZnPPIX as a fluorescence probe, the effect of Na+ on Pb2+ detection is subsequently investigated. The presence of Na+ (varied from 0.3 mM to 500 mM) simultaneously increases the read-out and background fluorescence, which results in a decreased signal-to...
- Published
- 2016
33. Thermoreversible Morphology and Conductivity of a Conjugated Polymer Network Embedded in Block Copolymer Self-Assemblies
- Author
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Zhe Zhang, Kunlun Hong, Youngkyu Han, Bobby G. Sumpter, Gregory S. Smith, Jan-Michael Y. Carrillo, Changwoo Do, Yunchao Li, Michael Ohl, and Mariappan Parans Paranthaman
- Subjects
Materials science ,Polymers ,Thiophenes ,02 engineering and technology ,Molecular Dynamics Simulation ,Conductivity ,Conjugated system ,010402 general chemistry ,01 natural sciences ,Polyethylene Glycols ,Biomaterials ,X-Ray Diffraction ,Phase (matter) ,Scattering, Small Angle ,Polymer chemistry ,Side chain ,Copolymer ,General Materials Science ,chemistry.chemical_classification ,Electric Conductivity ,Temperature ,General Chemistry ,Polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Dielectric spectroscopy ,Solutions ,Neutron Diffraction ,Chemical engineering ,chemistry ,Dielectric Spectroscopy ,Self-assembly ,0210 nano-technology ,Biotechnology - Abstract
Self-assembly of block copolymers provides numerous opportunities to create functional materials, utilizing self-assembled microdomains with a variety of morphology and periodic architectures as templates for functional nanofillers. Here new progress is reported toward the fabrication of thermally responsive and electrically conductive polymeric self-assemblies made from a water-soluble poly(thiophene) derivative with short poly(ethylene oxide) side chains and Pluronic L62 block copolymer solution in water. The structural and electrical properties of conjugated polymer-embedded self-assembled architectures are investigated by combining small-angle neutron and X-ray scattering, coarse-grained molecular dynamics simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporating them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellar-to-lamellar phase transition defines the embedded conjugated polymer network. As a result, the conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. This study shows promise for enabling more flexibility in processing and utilizing water-soluble conjugated polymers in aqueous solutions for self-assembly based fabrication of stimuli-responsive nanostructures and sensory materials.
- Published
- 2016
34. Aptamer-Based K+ Sensor: Process of Aptamer Transforming into G-Quadruplex
- Author
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Xiaohong Li, Juan Han, Yunchao Li, Dongju Zhang, and Louzhen Fan
- Subjects
Spectrometry, Mass, Electrospray Ionization ,Circular dichroism ,Aptamer ,Electrospray ionization ,Analytical chemistry ,02 engineering and technology ,010402 general chemistry ,G-quadruplex ,Mass spectrometry ,01 natural sciences ,Phase Transition ,Materials Chemistry ,Physical and Theoretical Chemistry ,Fluorescent Dyes ,Chemistry ,Native gel electrophoresis ,Circular Dichroism ,Aptamers, Nucleotide ,021001 nanoscience & nanotechnology ,Small molecule ,0104 chemical sciences ,Surfaces, Coatings and Films ,G-Quadruplexes ,Crystallography ,Spectrometry, Fluorescence ,Potassium ,0210 nano-technology ,Single strand - Abstract
G-rich aptamers have been widely applied to develop various sensors for detecting proteins, small molecules, and cations, which is based on the target-induced conformational transfer from single strand to G-quadruplex. However, the transforming process is unclear. Here, with PW17 as an aptamer example, the forming process of G-quadruplex induced by K(+) is investigated by circular dichroism spectroscopy, electrospray ionization mass spectroscopy, and native gel electrophoresis. The results demonstrate that PW17 undergoes a conformational transforming process from loose and unstable to compact and stable G-quadruplex, which is strictly K(+) concentration-dependent. The process contains three stages: (1) K(+) (0.5 mM) could induce PW17 forming a loose and unstable G-quadruplex; (2) the compact and stable K(+)-stabilized G-quadruplex is almost formed when K(+) is equal to or larger than 7 mM; and (3) when K(+) ranges from 0.5 mM to 7 mM, the transformation of K(+)-stabilized PW17 from loose and unstable to compact and stable occurs. Interestingly, dimeric G-quadruplex through 5'-5' stacking is involved in the forming process until completely formed at 40 mM K(+). Moreover, the total process is thermodynamically controlled. With PW17 as a sensing probe and PPIX as a fluorescent probe for detection of K(+), three linear fluorescent ranges are observed, which corresponds to the three forming stages of G-quadruplex. Clarifying the forming process provides a representative example to deeply understand and further design aptamer-based biosensers and logic devices.
- Published
- 2016
35. Tire-derived carbon composite anodes for sodium-ion batteries
- Author
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Richard J. Lee, Arumugam Manthiram, Sang Ok Kim, M. Parans Paranthaman, Sheng Dai, Yunchao Li, Amit K. Naskar, Kokouvi Akato, Alan M. Levine, and Jinshui Zhang
- Subjects
Materials science ,Waste management ,Renewable Energy, Sustainability and the Environment ,Sodium ,Composite number ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Energy storage ,0104 chemical sciences ,Anode ,Chemical engineering ,chemistry ,Tire recycling ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,0210 nano-technology ,Current density ,Carbon - Abstract
Hard-carbon materials are considered as one of the most promising anodes for the emerging sodium-ion batteries. Here, we report a low-cost, scalable waste tire-derived carbon as an anode for sodium-ion batteries (SIBs). Tire-derived carbons obtained by pyrolyzing acid-treated tire at 1100 °C, 1400 °C and 1600 °C show capacities of 179, 185 and 203 mAh g −1 , respectively, after 100 cycles at a current density of 20 mA g −1 in sodium-ion batteries with good electrochemical stability. The portion of the low-voltage plateau region in the charge-discharge curves increases as the heat-treatment temperature increases. The low-voltage plateau is beneficial to enhance the energy density of the full cell. This study provides a new pathway for inexpensive, environmentally benign and value-added waste tire-derived products towards large-scale energy storage applications.
- Published
- 2016
36. Monodispersed Li 4 Ti 5 O 12 with Controlled Morphology as High Power Lithium Ion Battery Anodes
- Author
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Mark Watson, Guoyi Fu, Stephen Harrison, Yunchao Li, and M. Parans Paranthaman
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,Scanning electron microscope ,Inorganic chemistry ,Energy Engineering and Power Technology ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,Electrochemistry ,01 natural sciences ,Lithium-ion battery ,Cathode ,0104 chemical sciences ,Anode ,law.invention ,Biomaterials ,Chemical engineering ,law ,Electrode ,Materials Chemistry ,0210 nano-technology - Abstract
Monodispersed Li4Ti5O12 (LTO) nanoparticles with controlled microstructure were successfully synthesized by a combination of hydrolysis and hydrothermal method followed by a post-annealing process. The scanning electron microscopy images showed that particles with a size of 30-40 nm were precisely controlled throughout the synthesis process. The electrochemical tests of the as-prepared LTO electrodes in a half-cell proved its high rate performance and outstanding cyclability which benefits from the preserved well-controlled nanoparticle size and morphology. LTO electrodes were also tested in a full cell configuration in pairing with LiFePO4 cathodes, which demonstrated a capacity of 147.3 mAh g-1. In addition, we have also demonstrated that LTO materials prepared using lithium salts separated from geothermal brine solutions had good cyclability. These demonstrations provide a promising way for making low-cost, large-scale LTO electrode materials for energy storage applications.
- Published
- 2016
37. Highly Water-soluble and Surface Charge-tunable Fluorescent Fullerene Nanoparticles: Facile Fabrication and Cellular Imaging
- Author
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Zifei Wang, Fanglong Yuan, Louzhen Fan, Hongtao Yu, Zetan Fan, Xiaohong Li, Yunchao Li, Rongbin Xie, and Hong Fan
- Subjects
Fullerene ,Materials science ,Fabrication ,General Chemical Engineering ,Nanoparticle ,Quantum yield ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,Electrochemistry ,Hydrothermal synthesis ,Surface charge ,0210 nano-technology ,Luminescence - Abstract
Water-soluble and surface charge-tunable amine-functionalized polyhydroxylated fullerene nanoparticles with a strong green emission were synthesized by grinding and hydrothermal treatment. The quantum yield of the nanoparticles was as high as 17%, which is the highest value recorded for fluorescent fullerene materials. The amine-functionalized polyhydroxylated fullerene nanoparticles with high surface charge were found to easily penetrate into breast cancer cells, HeLa cells and cardiac progenitor stem cells, opening up great opportunities for their bio-medical applications.
- Published
- 2016
38. Graphene quantum dots as smart probes for biosensing
- Author
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Yanting Liu, Zifei Wang, Rongbin Xie, Louzhen Fan, Xiaohong Li, Wei Zhou, and Yunchao Li
- Subjects
Materials science ,Photoluminescence ,Graphene ,business.industry ,General Chemical Engineering ,General Engineering ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Photobleaching ,0104 chemical sciences ,Analytical Chemistry ,Highly sensitive ,law.invention ,law ,Quantum dot ,Electrochemiluminescence ,Optoelectronics ,Electrochemical biosensor ,0210 nano-technology ,business ,Biosensor - Abstract
In recent years, graphene quantum dots (GQDs) have attracted tremendous attention for their potential for biological, optoelectronic and energy-related applications, owing to their excellent biocompatibility, low cytotoxicity, stable photoluminescence (PL) and resistance to photobleaching. Among these applications, GQD-based biosensors are rapidly developed due to their particular PL, electrochemiluminescence (ECL) and electrochemical properties, which are highly sensitive to minute perturbations. In this review, recent exciting progress in GQD-based biosensors, such as PL sensors, ECL sensors and electrochemical sensors is highlighted. First, the synthesis and the fundamental properties of GQDs are briefly introduced. Then, emerged applications of PL, ECL and electrochemical biosensors are mainly addressed. Finally, their future potential developments are discussed and speculated.
- Published
- 2016
39. One-pot and high-yield preparation of ultrathin β-PbO nanowires and nanosheets for high-capacity positive electrodes in lead-acid batteries
- Author
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Chuansheng He, Yunchao Li, Simeng Hao, Guanjie Xing, Min Huang, Xiaohong Li, and Louzhen Fan
- Subjects
Materials science ,Passivation ,Mechanical Engineering ,Thermal decomposition ,Metals and Alloys ,Nanowire ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Anode ,Nanomaterials ,Chemical engineering ,Mechanics of Materials ,Yield (chemistry) ,Electrode ,Materials Chemistry ,0210 nano-technology ,Lead–acid battery - Abstract
To obtain high-capacity electrode materials and meanwhile actualize the reuse of scrap lead paste, a novel alkylamine-mediated thermolysis route is proposed herein for one-pot preparation of high-quality PbO nanomaterials, relying on the thermal decomposition of lead carboxylate in hot solvent in the presence of hexadecylamine (HDA). This synthetic route allows us to produce uniform PbO nanowires with a diameter of 7.1 nm and a length beyond 10 μm, and nanosheets and nanorings with a lateral size of ca. 310 nm on a gram scale, by simply tuning the alkylamine content or reaction time. In particular, we have employed various means to unveil the key role of HDA, i.e., precursor activation and surface passivation function, in the controlled preparation of such PbO nanomaterials. Impressively, when serving as the positive active materials for lead acid batteries (LABs), the anodes based on PbO nanowires displayed an excellent discharge performance: its discharge capacity and active material utilization ratios could reach 164.3 mA h/g and 68.5% respectively even at a discharge current density as high as 50 mA/g, which are superior to most of the previously-reported values. Such an excellent discharge performance was speculated to result from the synergization effect of the large ECSA, small charge transfer resistance and highly active exposed facets associated with the PbO nanowires.
- Published
- 2020
40. Exonuclease I-Hydrolysis Assisted Electrochemical Quantitation of Surface-Immobilized DNA Hairpins and Improved HIV-1 Gene Detection
- Author
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Xiaoyi Gao, Yunchao Li, Hua-Zhong Yu, Xinglin Wang, and Jiale He
- Subjects
Models, Molecular ,Surface Properties ,Immobilized Nucleic Acids ,02 engineering and technology ,Biosensing Techniques ,Electrochemistry ,Mole fraction ,01 natural sciences ,Redox ,Analytical Chemistry ,chemistry.chemical_compound ,Hydrolysis ,Base Sequence ,Chemistry ,010401 analytical chemistry ,Inverted Repeat Sequences ,021001 nanoscience & nanotechnology ,Combinatorial chemistry ,0104 chemical sciences ,Exodeoxyribonucleases ,Yield (chemistry) ,Electrode ,DNA, Viral ,HIV-1 ,Nucleic Acid Conformation ,0210 nano-technology ,Biosensor ,DNA - Abstract
The complete formation of stem-loop (i.e., hairpin) configuration on chip surface is of particular importance for the application of hairpin DNA (hpDNA) in building biosensors for various analytes with optimized performance. We report herein a convenient electrochemical protocol for evaluating the yield of hairpin DNA conformations upon self-assembly on electrode surface. As of the different hydrolysis capability of Exonuclease I (Exo I) toward single-stranded DNA (ssDNA) and hpDNA, we can selectively remove ssDNA from electrode but retain hpDNA strands; based on the changes in the cyclic voltammetric (CV) responses using [Ru(NH3)6]3+ as redox indicators, we can then determine the fraction of hairpin configurations in mixed DNA self-assembled monolayers (SAMs). It was discovered that the molar fraction of hairpin configuration formed on the surface is considerably lower than that in the binary deposition solution (containing both ssDNA and hpDNA). The accuracy of the Exo I-assisted electrochemical quantit...
- Published
- 2018
41. Synthesis and characterization of substituted garnet and perovskite-based lithium-ion conducting solid electrolytes
- Author
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Ayyakkannu Manivannan, M. Parans Paranthaman, Dominique E. Williams, Chetan Dhital, Karim Zaghib, Yunchao Li, Maria Abreu-Sepulveda, and Ashfia Huq
- Subjects
Materials science ,General Chemical Engineering ,Inorganic chemistry ,General Engineering ,Analytical chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Arrhenius plot ,0104 chemical sciences ,law.invention ,chemistry ,law ,Impurity ,Phase (matter) ,Ionic conductivity ,General Materials Science ,Calcination ,Lithium ,0210 nano-technology ,Perovskite (structure) ,Monoclinic crystal system - Abstract
Titanium, tantalum-substituted Li7La3Zr2-xAxO12 (LLZO, A = Ta, Ti) garnets, and chromium-substituted La(2/3)-xLi3xTi1-yCryO3 (LLTO) perovskites were prepared by a conventional solid-state reaction and the Pechini processes. The desired crystal phases were obtained by varying the calcination temperature and time, as well as the substitution concentration. All samples indicated decomposition of the precursors when heated above 750 °C and formation of the desired phase after heat treatment at higher temperatures. Neutron diffraction data shows the formation of a predominant cubic phase in the case of Ta-LLZO, and monoclinic phase with minor impurity phases for Cr-LLTO. Ionic conductivity for Ti-LLZO (Li7La3Zr1.4Ti0.6O12), Ta-LLZO (Li6.03La3Zr1.533Ta0.46O12), and Cr-LLTO (La(2/3)-xLi3xTi0.9Cr0.1O3) at room temperature were found to be 5.21 × 10−6, 1.01 × 10−6, and 1.2 × 10−4 S cm−1, respectively. The activation energies of the compounds were determined from the Arrhenius plot and were 0.44 eV (Ti0.6-LLZO), 0.54 eV (Ta0.5-LLZO), and 0.20 eV (Cr0.1-LLTO).
- Published
- 2015
42. Conduction below 100 °C in nominal Li6ZnNb4O14
- Author
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Lance W. Gill, Yunchao Li, Arumugam Manthiram, Yangyang Wang, Gabriel M. Veith, Alexei P. Sokolov, Miaofang Chi, Edward W. Hagaman, Cheng Ma, Mariappan Parans Paranthaman, Sheng Dai, and John B. Goodenough
- Subjects
Battery (electricity) ,Materials science ,Mechanical Engineering ,Analytical chemistry ,02 engineering and technology ,Electrolyte ,Conductivity ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Thermal conduction ,01 natural sciences ,Spectral line ,0104 chemical sciences ,Adsorption ,Mechanics of Materials ,Particle ,General Materials Science ,0210 nano-technology ,Porosity - Abstract
The increasing demand for a safe rechargeable battery with a high energy density per cell is driving a search for a novel solid electrolyte with a high Li+ or Na+ conductivity that is chemically stable in a working Li-ion or Na-ion battery. Li6ZnNb4O14 (LZNO) has been reported to exhibit a σ Li > 10−2 S cm−1 at 250 °C, but to disproportionate into multiple phases on cooling from 850 °C to room-temperature. An investigation of the room-temperature Li-ion conductivity in a porous pellet of a multiphase product of a nominal LZNO composition is shown to have bulk σ Li ≈ 3.3 × 10−5 S cm−1 at room-temperature that increases to 1.4 × 10−4 S cm−1 by 50 °C. 7Li MAS NMR spectra were fitted to two Lorentzian lines, one of which showed a dramatic increase with increasing temperature. A test for water stability indicates that Li+ may move to the particle and grain surfaces to react with adsorbed water as occurs in the garnet Li+ conductors.
- Published
- 2015
43. Revealing and Resolving the Restrained Enzymatic Cleavage of DNA Self-Assembled Monolayers on Gold: Electrochemical Quantitation and ESI-MS Confirmation
- Author
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Yunchao Li, Xinglin Wang, Hua-Zhong Yu, Xiaoyi Gao, and Mingxi Geng
- Subjects
Spectrometry, Mass, Electrospray Ionization ,Stereochemistry ,DNA, Single-Stranded ,02 engineering and technology ,Cleavage (embryo) ,01 natural sciences ,Ruthenium ,Analytical Chemistry ,chemistry.chemical_compound ,Hydrolysis ,Coordination Complexes ,Enzymatic hydrolysis ,Nucleotide ,Electrodes ,chemistry.chemical_classification ,Chemistry ,010401 analytical chemistry ,Self-assembled monolayer ,Electrochemical Techniques ,021001 nanoscience & nanotechnology ,Combinatorial chemistry ,0104 chemical sciences ,Exodeoxyribonucleases ,Nucleic acid ,Gold ,0210 nano-technology ,Biosensor ,Oxidation-Reduction ,DNA - Abstract
Herein we report a combined electrochemical and ESI-MS study of the enzymatic hydrolysis efficiency of DNA self-assembled monolayers (SAMs) on gold, platform systems for understanding nucleic acid surface chemistry and for constructing DNA-based biosensors. Our electrochemical approach is based on the comparison of the amounts of surface-tethered DNA nucleotides before and after Exonuclease I (Exo I) incubation using electrostatically bound [Ru(NH3)6]3+ as redox indicators. It is surprising to reveal that the hydrolysis efficiency of ssDNA SAMs does not depend on the packing density and base sequence, and that the cleavage ends with surface-bound shorter strands (9-13 mers). The ex-situ ESI-MS observations confirmed that the hydrolysis products for ssDNA SAMs (from 24 to 56 mers) are dominated with 10-15 mer fragments, in contrast to the complete digestion in solution. Such surface-restrained hydrolysis behavior is due to the steric hindrance of the underneath electrode to the Exo I/DNA binding, which is essential for the occurrence of Exo I-catalyzed processive cleavage. More importantly, we have shown that the hydrolysis efficiency of ssDNA SAMs can be remarkably improved by adopting long alkyl linkers (locating DNA strands further away from the substrates).
- Published
- 2017
44. Optical disc technology-enabled analytical devices: from hardware modification to digitized molecular detection
- Author
-
Yunchao Li, Xiaochun Li, Hua-Zhong Yu, and Samuel Weng
- Subjects
Computer science ,business.industry ,Reading (computer) ,010401 analytical chemistry ,Microfluidics ,02 engineering and technology ,Substrate (printing) ,021001 nanoscience & nanotechnology ,01 natural sciences ,Biochemistry ,Signal ,0104 chemical sciences ,Analytical Chemistry ,Software ,Computer data storage ,Electrochemistry ,Environmental Chemistry ,0210 nano-technology ,Biochip ,business ,Optical disc ,Spectroscopy ,Computer hardware - Abstract
Beyond their essential applications in portable data storage for the past 30 years, optical discs and corresponding recording/reading technologies have been extensively explored with the ultimate goal of creating novel analytical tools for on-site chemical analysis and point-of-care (POC) medical diagnosis. In particular, the disc media (CD, DVD, and BD) are proven to be inexpensive and versatile substrate materials for the preparation of various biochips and microfluidic systems; conventional computer drives and disc players are widely adapted for biochip signal reading and microscopic imaging. Herein we provide an overview of such optical disc technology-enabled analytical devices, e.g., integrated systems developed from specifically fabricated analog disks, modified optical drives, or adapted software algorithms.
- Published
- 2016
45. Ultrastable and Low-Threshold Random Lasing from Narrow-Bandwidth-Emission Triangular Carbon Quantum Dots
- Author
-
Louzhen Fan, Yunchao Li, Xiaohong Li, Zhaona Wang, Xiaoyu Shi, Shihe Yang, Fanglong Yuan, and Zifan Xi
- Subjects
Materials science ,business.industry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Narrow bandwidth ,Carbon quantum dots ,Optoelectronics ,0210 nano-technology ,business ,Lasing threshold - Published
- 2018
46. Bright Multicolor Bandgap Fluorescent Carbon Quantum Dots for Electroluminescent Light-Emitting Diodes
- Author
-
Xiaohong Li, Louzhen Fan, Zhibin Wang, Fanglong Yuan, Shihe Yang, Zhan'ao Tan, and Yunchao Li
- Subjects
Materials science ,business.industry ,Band gap ,Mechanical Engineering ,Quantum yield ,02 engineering and technology ,Electroluminescence ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Fluorescence ,Luminance ,0104 chemical sciences ,law.invention ,Mechanics of Materials ,law ,Monochrome ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Light-emitting diode ,Diode - Abstract
Multicolor bandgap fluorescent carbon quantum dots (MCBF-CQDs) from blue to red with quantum yield up to 75% are synthesized using a solvothermal method. For the first time, monochrome electroluminescent light-emitting diodes (LEDs) with MCBF-CQDs directly as an active emission layer are fabricated. The maximum luminance of blue LEDs reaches 136 cd m-2 , which is the best performance for CQD-based monochrome electroluminescent LEDs.
- Published
- 2016
47. Membrane-Based Gas Separation Accelerated by Hollow Nanosphere Architectures
- Author
-
Kimberly M. Nelson, Jennifer A. Schott, Shannon M. Mahurin, Sheng Dai, Mariappan Parans Paranthaman, Yunchao Li, Xiao-Guang Sun, Jinshui Zhang, and Wangcheng Zhan
- Subjects
Materials science ,Mechanical Engineering ,chemistry.chemical_element ,02 engineering and technology ,Microporous material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Membrane ,chemistry ,Chemical engineering ,Mechanics of Materials ,Mechanical strength ,Copolymer ,Molecule ,Coupling (piping) ,General Materials Science ,Gas separation ,Composite material ,0210 nano-technology ,Carbon - Abstract
The coupling of hollow carbon nanospheres with triblock copolymers is a promising strategy to fabricate mixed-matrix membranes. This is because the symmetric microporous shells combine with the hollow space to promote gas transport, and the unique soft-rigid molecular structure of triblock copolymers can accommodate a high loading of fillers without a significant loss of mechanical strength.
- Published
- 2016
48. Sustainable Waste Tire Derived Carbon Material as a Potential Anode for Lithium-Ion Batteries
- Author
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Richard J. Lee, Skyler L. Wistrom, Amit K. Naskar, Yunchao Li, Jianlin Li, Joseph S. Gnanaraj, Jonathan Lyle Wistrom, M. Parans Paranthaman, Kokouvi Akato, and Alan M. Levine
- Subjects
Materials science ,lithium-ion batteries ,lcsh:TJ807-830 ,Geography, Planning and Development ,lcsh:Renewable energy sources ,chemistry.chemical_element ,02 engineering and technology ,Management, Monitoring, Policy and Law ,010402 general chemistry ,Combustion ,01 natural sciences ,Graphite ,disordered carbon microstructure ,lcsh:Environmental sciences ,lcsh:GE1-350 ,Supercapacitor ,Renewable Energy, Sustainability and the Environment ,business.industry ,lcsh:Environmental effects of industries and plants ,Fossil fuel ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Anode ,battery grade carbon ,Surface coating ,lcsh:TD194-195 ,chemistry ,Chemical engineering ,surface coating ,0210 nano-technology ,business ,Pyrolysis ,Carbon ,pouch cells ,waste tires - Abstract
The rapidly growing automobile industry increases the accumulation of end-of-life tires each year throughout the world. Waste tires lead to increased environmental issues and lasting resource problems. Recycling hazardous wastes to produce value-added products is becoming essential for the sustainable progress of society. A patented sulfonation process followed by pyrolysis at 1100 °, C in a nitrogen atmosphere was used to produce carbon material from these tires and utilized as an anode in lithium-ion batteries. The combustion of the volatiles released in waste tire pyrolysis produces lower fossil CO2 emissions per unit of energy (136.51 gCO2/kW·, h) compared to other conventional fossil fuels such as coal or fuel&ndash, oil, usually used in power generation. The strategy used in this research may be applied to other rechargeable batteries, supercapacitors, catalysts, and other electrochemical devices. The Raman vibrational spectra observed on these carbons show a graphitic carbon with significant disorder structure. Further, structural studies reveal a unique disordered carbon nanostructure with a higher interlayer distance of 4.5 Å, compared to 3.43 Å, in the commercial graphite. The carbon material derived from tires was used as an anode in lithium-ion batteries exhibited a reversible capacity of 360 mAh/g at C/3. However, the reversible capacity increased to 432 mAh/g at C/10 when this carbon particle was coated with a thin layer of carbon. A novel strategy of prelithiation applied for improving the first cycle efficiency to 94% is also presented.
- Published
- 2018
49. Rhodamine-Functionalized Graphene Quantum Dots for Detection of Fe(3+) in Cancer Stem Cells
- Author
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Louzhen Fan, Nicolas H. Voelcker, Shixin Zhou, Xiaohong Li, Yunchao Li, Ruihua Guo, Guo, Ruihua, Zhou, Shixin, Li, Yunchao, Li, Xiaohong, Fan, Louzhen, and Voelcker, Nicolas H
- Subjects
cancer stem cells ,detection ,Quantum yield ,Apoptosis ,Biocompatible Materials ,02 engineering and technology ,Photochemistry ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,Drug Delivery Systems ,law ,Rhodamine B ,Electrochemistry ,General Materials Science ,Microscopy, Confocal ,Cell Differentiation ,021001 nanoscience & nanotechnology ,Fluorescence ,3. Good health ,Neoplastic Stem Cells ,Graphite ,0210 nano-technology ,inorganic chemicals ,Materials science ,Biocompatibility ,Cell Survival ,Iron ,Nanotechnology ,010402 general chemistry ,Rhodamine ,Microscopy, Electron, Transmission ,Nanosensor ,Quantum Dots ,Biomarkers, Tumor ,Humans ,Cell Lineage ,Cell Proliferation ,graphene quantum dots ,Graphene ,Rhodamines ,Water ,rhodamine B derivative ,0104 chemical sciences ,Pancreatic Neoplasms ,chemistry ,Fe3+ ,Solubility ,Quantum dot ,HeLa Cells - Abstract
A turn-on orange-red fluorescent nanosensor based on rhodamine B derivative-functionalized graphene quantum dots (RBD-GQDs) has been successfully synthesized for Fe3+ detection with high sensitivity and selectivity. By connecting with GQDs, the water solubility, sensitivity, photostability, and biocompatibility of RBD are drastically improved. The most distinctive feature of the RBD-GQDs, which sets them apart from other previously reported fluorophores or GQDs, is that they with the detection limits as low as 0.02 μM are demonstrated as a Fe3+ turn-on fluorescent nanosensor in cancer stem cells. Fe3+ binding to such GQDs (RBD-GQDs-Fe3+) with orange-red fluorescence of 43% quantum yield were demonstrated to be the biomarkers for cancer stem cell imaging. Refereed/Peer-reviewed
- Published
- 2015
50. 53% Efficient Red Emissive Carbon Quantum Dots for High Color Rendering and Stable Warm White‐Light‐Emitting Diodes
- Author
-
Louzhen Fan, Xiaohong Li, Shihe Yang, Zifei Wang, Fanglong Yuan, Yunchao Li, and Haizheng Zhong
- Subjects
Materials science ,business.industry ,Mechanical Engineering ,Quantum yield ,Phosphor ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,medicine.disease_cause ,01 natural sciences ,0104 chemical sciences ,Rendering (computer graphics) ,Color rendering index ,Optics ,Mechanics of Materials ,Carbon quantum dots ,High color ,medicine ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Ultraviolet ,Diode - Abstract
Red emissive carbon quantum dots (R-CQDs) with quantum yield of 53% is successfully prepared. An ultraviolet (UV)-pumped CQD phosphors-based warm white light-emitting diode (WLED) is realized for the first time and achieves a color rendering index of 97. This work provides a new avenue for the exploration of low cost, environment-friendly, and high-performance CQD phosphors-based warm WLEDs.
- Published
- 2017
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