Publications by authors named "Bingwen Hu"

75 Publications

Structural characterization and statistical properties of jammed soft ellipsoid packing.

Soft Matter 2021 Mar;17(10):2963-2972

Shanghai Key Laboratory of Magnetic Resonance, Institute of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, P. R. China.

The jamming transition and jammed packing structures of hydrogel soft ellipsoids are studied using magnetic resonance imaging techniques. As the packing fraction increases, the fluctuation of local free volume decreases and the fluctuation of particle deformation increases. Effective thermodynamic quantities are obtained by characterizing these fluctuations using k-gamma distributions based on an underlying statistical model for granular materials. Surprisingly, the two granular temperatures measuring the relative fluctuations of both free volume and particle deformation remain basically unchanged as the packing fraction increases. The total configurational entropy is also approximately constant for packing with different packing fractions. The significantly different behaviors of these effective thermodynamic quantities compared with hard sphere systems are further attributed to a statistically affine structural transformation of the packing structures along with particle deformations when the packing fraction changes.
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http://dx.doi.org/10.1039/d0sm01699cDOI Listing
March 2021

Operando EPR and EPR Imaging Study on a NaCrO Cathode: Electronic Property and Structural Degradation with Cr Dissolution.

J Phys Chem Lett 2021 Jan 7;12(2):781-786. Epub 2021 Jan 7.

Shanghai Key Laboratory of Magnetic Resonance, State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200062, P.R. China.

NaCrO is a potential cathode material for sodium-ion batteries due to its low cost, safety, and high power. It is necessary to further understand its electronic property during cycling in advance of practical application. In this work, operando EPR is carried out to monitor the evolution of the electronic structure for NaCrO cycled between 2.2-3.6 V and 2.2-4.5 V. We discover that electronic delocalization takes place at the early stage of charge, which may account for the excellent rate performance. In addition, via EPR imaging, an EPR signal associated with the irreversible phase transition at 3.8 V is located in the electrolyte, which is then attributed to the Cr ions dissolved with the surface reconstruction. These findings may help researchers to better design and modify the Cr-based cathode materials.
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http://dx.doi.org/10.1021/acs.jpclett.0c03327DOI Listing
January 2021

Restraining Oxygen Loss and Boosting Reversible Oxygen Redox in a P2-Type Oxide Cathode by Trace Anion Substitution.

ACS Appl Mater Interfaces 2021 Jan 30;13(1):360-369. Epub 2020 Dec 30.

Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, P. R. China.

Oxygen redox has recently emerged as a lever to boost the specific energy density of layered sodium transition metal oxide cathode materials. However, the oxygen redox reaction is universally confronted with concomitant issues such as irreversible lattice oxygen loss and parasitical electrolyte degradation, thus debilitating cycling stability. Herein, a novel F-substituted layered structure P2-NaLiMnOF cathode is designed, which exhibits superb capacity retention (183.6 mAh g after 50 cycles at 0.05C, 87.8% of the highest discharge capacity) and rate capability (105.5 mAh g at 5C) in Na half-cells. Such results are nontrivial as this system only contains the low-cost Mn transition metal element. Moreover, by systematic bulk/surface spectroscopy evidence (hard and soft X-ray absorption spectroscopy, electron paramagnetic resonance, and operando differential electrochemical mass spectrometry), we explicitly corroborate that the irreversible oxygen evolution and notorious Jahn-Teller distortion are effectively subdued by trace F-substitution. In addition, a higher oxygen vacancy formation energy for the F-substituted structure was demonstrated via density functional theory calculations. Anionic substitution could therefore be an impactful solution to boost reversible oxygen redox chemistry for layered sodium oxide cathodes.
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http://dx.doi.org/10.1021/acsami.0c16236DOI Listing
January 2021

Superionic Conductors Bulk Interfacial Conduction.

J Am Chem Soc 2020 Oct 7;142(42):18035-18041. Epub 2020 Oct 7.

School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, and in situ Center for Physical Sciences, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.

Superionic conductors with ionic conductivity on the order of mS cm are expected to revolutionize the development of solid-state batteries (SSBs). However, currently available superionic conductors are limited to only a few structural families such as garnet oxides and sulfide-based glass/ceramic. Interfaces in composite systems such as alumina in lithium iodide have long been identified as a viable ionic conduction channel, but practical superionic conductors employing the interfacial conduction mechanism are yet to be realized. Here we report a novel method that creates continuous interfaces in the bulk of composite thin films. Ions can conduct through the interface, and consequently, the inorganic phase can be ionically insulating in this type of bulk interface superionic conductors (BISCs). Ionic conductivities of lithium, sodium, and magnesium ion BISCs have reached 1.16 mS cm, 0.40 mS cm, and 0.23 mS cm at 25 °C in 25 μm thick films, corresponding to areal conductance as high as 464 mS cm, 160 mS cm, and 92 mS cm, respectively. Ultralow overpotential and stable long-term cycling for up to 5000 h were obtained for solid-state Li metal symmetric batteries employing Li ion BISCs. This work opens new structural space for superionic conductors and urges for future investigations on detailed conduction mechanisms and material design principles.
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http://dx.doi.org/10.1021/jacs.0c07060DOI Listing
October 2020

Deciphering the Origin of High Electrochemical Performance in a Novel Ti-Substituted P2/O3 Biphasic Cathode for Sodium-Ion Batteries.

ACS Appl Mater Interfaces 2020 Sep 6;12(37):41485-41494. Epub 2020 Sep 6.

Shanghai Key Laboratory of Magnetic Resonance, State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, 200062 Shanghai, P. R. China.

The layered Mn-based oxides (NaMnO), which is one of the most promising cathode families for rechargeable sodium-ion batteries, have received considerable attention because of their tunable electrochemical performances and low costs. Herein, a novel P2/O3 intergrown Li-containing NaLiMnTiO cathode material prepared by Ti-substitution into Mn-site is reported. Benefiting from the synergistic effects of the biphasic composite structure and inactive d element substitution, this P2/O3 electrode exhibits high initial charge/discharge capacity and excellent cycling performance. The combination of different characterization techniques including solid-state NMR, electron paramagnetic resonance, X-ray adsorption spectroscopy, and high-resolution transmission electron microscopy gives insights into the local electronic environment, the redox chemistry, and also the microstructure rigidity of these cathode materials upon cycling. On the basis of comprehensive comparison with the Ti-free P2/O3-NaLiMnO, the observed improvement on the electrochemical performance is primarily attributed to the mitigation of notorious Mn/Mn redox and the enhanced stability of the oxygen charge compensation behavior. From the viewpoint of structure evolution, Ti-substitution restrains the Li loss and irreversible structural degradation during cycling. This study provides an in-depth understanding of the electronic and crystal structure evolutions after inactive d element substitution and may shed light on the rational design of high-performance P2/O3 biphasic Mn-based layered cathodes.
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http://dx.doi.org/10.1021/acsami.0c11427DOI Listing
September 2020

Cu-Doped P2-NaMnCuO Sodium-Ion Battery Cathode with Enhanced Electrochemical Performance: Insight from Water Sensitivity and Surface Mn(II) Formation Studies.

ACS Appl Mater Interfaces 2020 Aug 23;12(31):34848-34857. Epub 2020 Jul 23.

State Key Laboratory of Precision Spectroscopy, Shanghai Key of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, PR China.

Sodium-ion batteries (SIBs) show great application prospects in large-scale energy storage. P2-type manganese-based layered oxides have received special attention by virtue of their high theoretical capacity, low cost, and environmental friendliness. However, water sensitivity and limited cycling stability hinder their application, especially since the underlying mechanisms for the above two issues are still unclear. In this work, copper substitution is used to suppress the Jahn-Teller effect of Mn and affect the corresponding lattice structure. The water sensitivity and charge compensation mechanism were carefully investigated. Results demonstrate that water sensitivity of the electrode is related to the order of Na/vacancy in the Na interlayers since water molecules are more easily inserted into the charged state electrodes, but the tendency for the water uptake does not increase with Na extraction. Furthermore, Mn forms on the surface of electrodes in the initial discharge process, and the redox reaction in the bulk is predominantly between Mn and Mn. Cu-substituted in TM layer affects the arrangement of Na/vacancy and suppresses the Mn formation on the NaMnCuO electrode that results in superior air stability and better storage properties.
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http://dx.doi.org/10.1021/acsami.0c07244DOI Listing
August 2020

Revealing the Formation of Well-Dispersed Polystyrene@ZIF-8 Core-Shell Nanoparticles by Analytical Ultracentrifugation.

Langmuir 2020 Jul 17;36(29):8589-8596. Epub 2020 Jul 17.

State Key Laboratory of Precision Spectroscopy, Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China.

Significant progress has been made in the synthesis and application of core-shell nanoparticles in the past decade. But particle agglomerations are hard to avoid as the formation mechanisms of core-shell nanoparticles are still vague and not clear even for the simplest and most straightforward hard-templating method. Here, analytical ultracentrifugation (AUC) is applied to investigate the formation of polystyrene@ZIF-8 core-shell nanoparticles, as a model to understand the hard-templating method. It has been found that the concentration of the ZIF-8 precursor influences both the ZIF-8 shell formation and the agglomeration of the polystyrene (PS) template. An overdiluted ZIF-8 precursor is not suitable for ZIF-8 shell formation, while a highly concentrated ZIF-8 precursor causes strong aggregation of the PS core. By applying the optimal precursor concentration identified by AUC, well-dispersed polystyrene@ZIF-8 core-shell nanoparticles can be obtained.
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http://dx.doi.org/10.1021/acs.langmuir.0c01467DOI Listing
July 2020

Unsupervised Eyeglasses Removal in the Wild.

IEEE Trans Cybern 2020 Jun 8;PP. Epub 2020 Jun 8.

Eyeglasses removal is challenging in removing different kinds of eyeglasses, e.g., rimless glasses, full-rim glasses, and sunglasses, and recovering appropriate eyes. Due to the significant visual variants, the conventional methods lack scalability. Most existing works focus on the frontal face images in the controlled environment, such as the laboratory, and need to design specific systems for different eyeglass types. To address the limitation, we propose a unified eyeglass removal model called the eyeglasses removal generative adversarial network (ERGAN), which could handle different types of glasses in the wild. The proposed method does not depend on the dense annotation of eyeglasses location but benefits from the large-scale face images with weak annotations. Specifically, we study the two relevant tasks simultaneously, that is, removing eyeglasses and wearing eyeglasses. Given two face images with and without eyeglasses, the proposed model learns to swap the eye area in two faces. The generation mechanism focuses on the eye area and invades the difficulty of generating a new face. In the experiment, we show the proposed method achieves a competitive removal quality in terms of realism and diversity. Furthermore, we evaluate ERGAN on several subsequent tasks, such as face verification and facial expression recognition. The experiment shows that our method could serve as a preprocessing method for these tasks.
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http://dx.doi.org/10.1109/TCYB.2020.2995496DOI Listing
June 2020

Simple Transformation of Covalent Organic Frameworks to Highly Proton-Conductive Electrolytes.

ACS Appl Mater Interfaces 2020 Feb 6;12(7):8198-8205. Epub 2020 Feb 6.

College of Materials Science and Engineering , Huaqiao University , Xiamen 361021 , China.

We report the rational design and implementation of a new class of gel guest-assisted, ionic covalent organic framework (COF) membranes that exhibit superior H conduction. The as-synthesized COFs are postmodified via a lithiation (or sodiation) treatment. The hydrophilic Li or Na ions in the COFs form a dense and extensive hydrogen-bonding network of HO molecules with mobile H at the periphery, thereby transforming COFs into H conductors. Then, the ionic COFs are assembled into a flexible H conductor membrane via a gelation process, where the organic gel provides both mechanical strength and additional H carriers for fast H conduction. The final COF-based membrane exhibits an excellent H conductivity of 1.3 × 10 S cm at 313 K and 98% relative humidity, which are the highest values of the COF-based H conductors reported until now and are even comparable with those of the typical commercial Nafion membrane. We anticipate that the two-in-one strategy would open up a porous COF-driven new molecular framework and membrane architectural design/opportunity for development of next-generation ionic conductors.
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http://dx.doi.org/10.1021/acsami.9b19953DOI Listing
February 2020

High Ethylene Selectivity in Methanol-to-Olefin (MTO) Reaction over MOR-Zeolite Nanosheets.

Angew Chem Int Ed Engl 2020 Apr 18;59(15):6258-6262. Epub 2020 Feb 18.

Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, North Zhongshan Road 3663, Shanghai, 200062, China.

Precisely controlled crystal growth endows zeolites with special textural and catalytic properties. A nanosheet mordenite zeolite with a thickness of ca. 11 nm, named as MOR-NS, has been prepared using a well-designed gemini-type amphiphilic surfactant as bifunctional structure-directing agent (SDA). Its benzyl diquarternary ammonium cations structurally directed the formation of MOR topology, whereas the long and hydrophobic hexadecyl tailing group prevented the extensive crystal growth along b axis. This kind of orientated crystallization took place through the inorganic-organic interaction between silica species and SDA molecules present in the whole process. The thin MOR nanosheets, with highly exposed (010) planes and 8-membered ring (MR) windows, exhibited a much improved ethylene selectivity (42.1 %) for methanol-to-olefin (MTO) reactions when compared with conventional bulk MOR crystals (3.3 %).
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http://dx.doi.org/10.1002/anie.202000269DOI Listing
April 2020

A rings-in-pores net: crown ether-based covalent organic frameworks for phase-transfer catalysis.

Chem Commun (Camb) 2020 Jan 12;56(4):595-598. Epub 2019 Dec 12.

Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.

We herein present a new family of crown ether-based covalent organic frameworks (CE-COFs) for the first time. The CE-COFs show excellent phase-transfer catalytic performance in various nucleophilic substitution reactions.
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http://dx.doi.org/10.1039/c9cc07639eDOI Listing
January 2020

Unveiling the benefits of potassium doping on the structural integrity of Li-Mn-rich layered oxides during prolonged cycling by dual-mode EPR spectroscopy.

Phys Chem Chem Phys 2019 Nov;21(43):24017-24025

Shanghai Key Laboratory of Magnetic Resonance, State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200062, P. R. China.

The oxygen redox process in Li- and Mn-rich layered oxides will inevitably lead to the generation of oxygen vacancies on the surface and their subsequent injection into the bulk lattice, which incurs poor kinetics, capacity decrease, and voltage fading. Herein, this predicament is effectively alleviated by bulk doping of K+, which is intrinsically stable in the lattice to inhibit the generation of oxygen vacancies in the deep delithiated state. More importantly, the benefits of K+ doping on the structural reversibility during prolonged cycling were studied by electron paramagnetic resonance (EPR) spectroscopy in both perpendicular and parallel polarization modes and high-resolution transmission electron microscopy. The results elucidate that the migration of transition-metal ions and oxygen vacancies and the reduction of Mn-ions are mitigated after K+ doping. Consequently, the growth of Li-poor nanovoids in the bulk lattice is greatly diminished and the structural transition from layered to spinel phases is effectively delayed.
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http://dx.doi.org/10.1039/c9cp04204kDOI Listing
November 2019

Monitoring the evolution of local oxygen environments during LiCoO charging via ex situO NMR.

Chem Commun (Camb) 2019 Jul 12;55(52):7550-7553. Epub 2019 Jun 12.

Shanghai Key Laboratory of Magnetic Resonance, State Key Laboratory of Precision Spectroscopy, School of Physics and Materials Science, East China Normal University, Shanghai 200062, China.

LiCoO has been labelled with O from O-enriched water, and then examined viaLi, O and Co solid-state NMR at different charge states. The results reveal the atomic-level environment evolution during the phase transitions, and O NMR is found to be more sensitive to the subtle structural changes.
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http://dx.doi.org/10.1039/c9cc03304aDOI Listing
July 2019

Low-temperature pseudomorphic transformation of polyhedral MIL-88A to lithium ferrite (LiFeO) in aqueous LiOH medium toward high Li storage.

Nanoscale 2019 Jun;11(24):11892-11901

College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310036, PR China.

The ability to develop novel nanomaterials, and to precisely manufacture their functional structures at the nano- and microscales would benefit many emerging device applications. Herein, as a first example, we describe the exploration of feasibility for the morphological replacement of an iron-based MOF bearing trimeric FeIII-O clusters, MIL-88A preform, with a polyhedral architecture of around 0.4 × 1.2 μm by a lithium ferrite (LiFe3O5) phase via solid-liquid pseudomorphic transformation reactions in biologically and environmentally favourable aqueous lithium hydroxide (LiOH). The reaction proceeds at 170 °C, and the overall reaction can be described as Fe3O(H2O)2(FMA)3(OH)·nH2O (MIL-88A) + 7OH- + Li+ → LiFe3O5 + 3FMA2- + (n + 6) H2O (FMA = fumarate). It was proposed that through the coordination substitution of a MOF ligand by OH-, follow-up dehydration and dehydroxylation, and final H+/Li+ ionic exchange, the monolithiated iron oxides formed thermodynamically at comparatively low temperatures, which transcribe the global nanostructure morphologies of the polyhedral MOF preforms with the hexagonal symmetry, but were composed of interconnected LiFe3O5 particles (about 16 nm) that crystallize in a typical magnetite-type cubic (Fd3[combining macron]m) structure. Given the characteristic texture and structure of the Li-Fe oxide replica, cubic LiFe3O5 was preferentially employed as a new type of electrode material in rechargeable lithium cells. Notably, from the electrochemical evaluation, this metal oxide system exhibits decent anodic performances by undergoing a nine-electron conversion reaction, showing a substantially high specific capacity with an average potential of 0.8 V versus lithium metal, a long service life (700 cycles), and exceptional high-rate capability (up to 2.0 A g-1). The synthetic paradigms demonstrated that the MIL-88A to LiFe3O5 conversion may be transferable to other advanced inorganic-based electrodes from the parent metal compound such as LiFeO2, LiMn2O4 or LiCoO2 toward sustainable energy fields.
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http://dx.doi.org/10.1039/c9nr03006aDOI Listing
June 2019

A comprehensive study on the generation of reactive oxygen species in Cu-Aβ-catalyzed redox processes.

Free Radic Biol Med 2019 05 5;135:125-131. Epub 2019 Mar 5.

State Key Laboratory of Precision Spectroscopy, East China Normal University, North Zhongshan Road 3663, Shanghai, 200062, China; Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Dongchuan Road 500, Shanghai, 200241, China. Electronic address:

In the amyloid plaques, a signature of AD, abnormally high Cu concentrations are found bound to Aβ. Most of previous studies reported that Cu-Aβ could contribute to oxidative stress, as HO and •OH are catalytically generated by Cu-Aβ with the assistance of biological reductant, with only one recent report stated that free O is also generated in the Cu-Aβ catalyzed processes, where an indirect technique was applied. To comprehensively investigate the free radicals produced during this Cu-Aβ-mediated process with a biological reductant, DNA-cleavage assay, an indirect method, and two direct methods including electron paramagnetic resonance (EPR) spectroscopy and transient absorption spectroscopy (TAS), both having qualitative and quantitative power, were employed in this work. All the experimental results obtained from the three methods demonstrated that Cu-Aβ in the biological reducing environment was not only able to catalyze the production of HO and •OH, but also to generate free O. The results further indicated that O was the precursor of HO and •OH. It is also important to note that the results obtained from EPR spectroscopy and TAS provided direct evidence for the presence of O and •OH. By virtue of the direct techniques, we also found that the longest peptide fragments of Aβ, Aβ, and Aβ produced the least radicals with a lowest rate. More interestingly, the fibrillar forms of Aβ generated less O and •OH compared with oligomeric and monomeric forms.
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http://dx.doi.org/10.1016/j.freeradbiomed.2019.02.030DOI Listing
May 2019

One-Pot Synthesis of Co-Based Coordination Polymer Nanowire for Li-Ion Batteries with Great Capacity and Stable Cycling Stability.

Nanomicro Lett 2018 8;10(2):19. Epub 2017 Dec 8.

State Key Laboratory of Precision Spectroscopy, Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, East China Normal University, Shanghai, 200062 People's Republic of China.

Nanowire coordination polymer cobalt-terephthalonitrile (Co-BDCN) was successfully synthesized using a simple solvothermal method and applied as anode material for lithium-ion batteries (LIBs). A reversible capacity of 1132 mAh g was retained after 100 cycles at a rate of 100 mA g, which should be one of the best LIBs performances among metal organic frameworks and coordination polymers-based anode materials at such a rate. On the basis of the comprehensive structural and morphology characterizations including fourier transform infrared spectroscopy, H NMR, C NMR, and scanning electron microscopy, we demonstrated that the great electrochemical performance of the as-synthesized Co-BDCN coordination polymer can be attributed to the synergistic effect of metal centers and organic ligands, as well as the stability of the nanowire morphology during cycling.
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http://dx.doi.org/10.1007/s40820-017-0177-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6199072PMC
December 2017

High-fidelity spectroscopy reconstruction in accelerated NMR.

Chem Commun (Camb) 2018 Sep;54(78):10958-10961

Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen 361005, China.

Non-uniform sampling significantly accelerates the data acquisition time in NMR spectroscopy, but spectra must be reconstructed with appropriate methods. A high-fidelity reconstruction method is proposed to preserve low-intensity spectral peaks and provide stable reconstruction under different sampling trials.
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http://dx.doi.org/10.1039/c8cc06132gDOI Listing
September 2018

Reduction of the C cross-polarization experimental time for pharmaceutical samples with long T by ball milling in solid-state NMR.

Solid State Nucl Magn Reson 2018 10 4;94:20-25. Epub 2018 Aug 4.

State Key Laboratory of Precision Spectroscopy & Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, East China Normal University, Shanghai, 200062, China. Electronic address:

Many pharmaceutical samples have notably long H T (proton spin-lattice relaxation time), leading to lengthy experiments lasting several days in solid-state NMR studies. In this work, we propose the use of ball milling on the pharmaceutical samples to reduce the H T, which also leads to enhanced sensitivity in {H}-C Cross-Polarization (CP) experiments due to reduced particle sizes and increased surface areas of the samples. Experimentally, we determined that depending on the substrates and milling time, the signal-to-noise ratio (S/N) of a 1D C CP spectrum can be increased by a factor of 3-6, which means that the experimental time can be shortened by a factor of 9-36. Furthermore, the application of simple ball-milling within a short time avoids the amorphization of the studied samples such that no signal due to amorphous state is observed in the C CP spectrum. This simple ball milling method used for sensitivity enhancement can be further applied in the SS-NMR studies of pharmaceutical samples.
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http://dx.doi.org/10.1016/j.ssnmr.2018.08.001DOI Listing
October 2018

N overtone nuclear magnetic resonance of rotating solids.

J Chem Phys 2018 Aug;149(6):064201

Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, East China Normal University, Shanghai 200062, China.

By irradiating and observing at twice the N Larmor frequency, overtone (OT) nuclear magnetic resonance (NMR) is capable of obtaining N spectra without first-order quadrupolar broadening. Direct excitation and detection of the usually "forbidden" double-quantum transition is mediated by the perturbation from the large quadrupole interaction to the spin states quantized by the Zeeman interaction. A recent study [L. A. O'Dell and C. I. Ratcliffe, Chem. Phys. Lett. , 168 (2011)] has shown that N NMR under magic-angle spinning (MAS) can yield high-resolution spectra with typical second-order quadrupolar line shapes allowing the measurement of N chemical shift and quadrupolar coupling parameters. This article has also shown that under MAS the main N peak is shifted by twice the sample spinning frequency with respect to its static position. We present the theory of N NMR of static or rotating samples and the physical picture of the intriguing spinning-induced shift in the second case. We use perturbation theory for the case of static samples and Floquet theory for rotating samples. In both cases, the results can be described by a so-called OT parameter that scales down the N radio-frequency () excitation and signal detection. This OT parameter shows that the components of the field, which are transverse and longitudinal with respect to the magnetic field, are both effective for N excitation and signal detection. In the case of MAS at angular frequency , the superposition of the excitation and detection components in the OT parameter makes either the +2 or -2 term the dominant N signal, depending on the sense of sample spinning with respect to the magnetic field. This leads to an apparent N signal shifted at twice the spinning frequency. The features of N NMR spectra for both static and rotating samples are illustrated with simulations. The spinning induced shift and its dependence on the spinning direction are confirmed experimentally by reversing the spinning direction and the field of the 36 T series-connected hybrid magnet at the US National High Magnetic Field Laboratory.
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http://dx.doi.org/10.1063/1.5044653DOI Listing
August 2018

Indirect detection of broad spectra in solid-state NMR using interleaved DANTE trains.

J Magn Reson 2018 Sep 10;294:101-114. Epub 2018 Jul 10.

Univ. Lille, CNRS, UMR 8181-UCCS, Unité de Catalyse et de Chimie du Solide, F-59000 Lille, France; Institut Universitaire de France, 1, rue Descartes, 75231 Paris, France. Electronic address:

We analyze the performances and the optimization of H-{I} HMQC experiments using basic and interleaved DANTE schemes for the indirect detection of nuclei I = 1/2 or 1 exhibiting wide lines dominated by chemical shift anisotropy (CSA) or quadrupole interaction, respectively. These sequences are first described using average Hamiltonian theory. Then, we analyze using numerical simulations (i) the optimal lengths of the DANTE train and the individual pulses, (ii) the robustness of these experiments to offset, and (iii) the optimal choice of the defocusing and refocusing times for both H-{I} J- and D-HMQC sequences for Pt (I = 1/2) and N (I = 1) nuclei subject to large CSA and quadrupole interaction, respectively. These simulations are compared to H-{N} D-HMQC experiments on γ-glycine and L-histidine.HCl at B = 18.8 T and MAS frequency of 62.5 kHz. The present study shows that (i) the optimal defocusing and refocusing times do not depend on the chosen DANTE scheme, (ii) the DANTE trains must be applied with the highest rf-field compatible with the probe specifications and the stability of the sample, (iii) the excitation bandwidth along the indirect dimension of HMQC sequence using DANTE trains is inversely proportional to their length, (iv) interleaved DANTE trains increase the excitation bandwidth of these sequences, and (v) dephasing under residual H-H and H-I dipolar couplings, as well as N second-order quadrupole interaction, during the length of the DANTE scheme attenuate the transfer efficiency.
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http://dx.doi.org/10.1016/j.jmr.2018.07.005DOI Listing
September 2018

Uniform signal enhancement in MAS NMR of half-integer quadrupolar nuclei using quadruple-frequency sweeps.

J Magn Reson 2018 Aug 15;293:92-103. Epub 2018 Jun 15.

National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, 430071 Wuhan, China. Electronic address:

We introduce two MAS schemes that allow manipulating the satellite-transition (ST) populations of half-integer quadrupolar nuclei, and which both exhibit improved robustness to the quadrupolar coupling constant (C). These schemes, called quadruple frequency sweep (QFS) or quadruple WURST (QWURST) are the sums of two DFS or four WURST to efficiently invert the ST populations of nuclei subject to large or small quadrupole interactions, simultaneously. These quadruple sweeps methods only require 6% more rf-power than the double sweeps ones. We demonstrate, both numerically and experimentally, that the QFS and QWURST schemes benefit from robustness to C and rf amplitude and offset and hence achieve uniform enhancement of the CT signal for Al nuclei subject to different quadrupole interactions. Although the version of QFS with repetitive accumulation can achieve higher enhancement in the S/N of the Al MAS spectrum, the final sensitivity gains mainly depend on the longitudinal relaxation time of different Al sites. We also confirm that these schemes provide an improved acceleration of the P-{Al} coherence transfer in PT-J-HMQC experiments.
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http://dx.doi.org/10.1016/j.jmr.2018.06.005DOI Listing
August 2018

Computer-aided diagnosis of prostate cancer using a deep convolutional neural network from multiparametric MRI.

J Magn Reson Imaging 2018 12 16;48(6):1570-1577. Epub 2018 Apr 16.

Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China.

Background: Deep learning is the most promising methodology for automatic computer-aided diagnosis of prostate cancer (PCa) with multiparametric MRI (mp-MRI).

Purpose: To develop an automatic approach based on deep convolutional neural network (DCNN) to classify PCa and noncancerous tissues (NC) with mp-MRI.

Study Type: Retrospective.

Subjects: In all, 195 patients with localized PCa were collected from a PROSTATEx database. In total, 159/17/19 patients with 444/48/55 observations (215/23/23 PCas and 229/25/32 NCs) were randomly selected for training/validation/testing, respectively.

Sequence: T -weighted, diffusion-weighted, and apparent diffusion coefficient images.

Assessment: A radiologist manually labeled the regions of interest of PCas and NCs and estimated the Prostate Imaging Reporting and Data System (PI-RADS) scores for each region. Inspired by VGG-Net, we designed a patch-based DCNN model to distinguish between PCa and NCs based on a combination of mp-MRI data. Additionally, an enhanced prediction method was used to improve the prediction accuracy. The performance of DCNN prediction was tested using a receiver operating characteristic (ROC) curve, and the area under the ROC curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Moreover, the predicted result was compared with the PI-RADS score to evaluate its clinical value using decision curve analysis.

Statistical Test: Two-sided Wilcoxon signed-rank test with statistical significance set at 0.05.

Results: The DCNN produced excellent diagnostic performance in distinguishing between PCa and NC for testing datasets with an AUC of 0.944 (95% confidence interval: 0.876-0.994), sensitivity of 87.0%, specificity of 90.6%, PPV of 87.0%, and NPV of 90.6%. The decision curve analysis revealed that the joint model of PI-RADS and DCNN provided additional net benefits compared with the DCNN model and the PI-RADS scheme.

Data Conclusion: The proposed DCNN-based model with enhanced prediction yielded high performance in statistical analysis, suggesting that DCNN could be used in computer-aided diagnosis (CAD) for PCa classification.

Level Of Evidence: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1570-1577.
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http://dx.doi.org/10.1002/jmri.26047DOI Listing
December 2018

Green and Rational Design of 3D Layer-by-Layer MnO Hierarchically Mesoporous Microcuboids from MOF Templates for High-Rate and Long-Life Li-Ion Batteries.

ACS Appl Mater Interfaces 2018 May 18;10(17):14684-14697. Epub 2018 Apr 18.

State Key Laboratory of Precision Spectroscopy, Shanghai Key Laboratory of Magnetic Resonance, Institute of Functional Materials, School of Physics and Materials Science , East China Normal University , Shanghai 200062 , P. R. China.

Rational design and delicate control on the textural properties of metal-oxide materials for diverse structure-dependent applications still remain formidable challenges. Here, we present an eco-friendly and facile approach to smartly fabricate three-dimensional (3D) layer-by-layer manganese oxide (MnO ) hierarchical mesoporous microcuboids from a Mn-MOF-74-based template, using a one-step solution-phase reaction scheme at room temperature. Through the controlled exchange of metal-organic framework (MOF) ligand with OH in alkaline aqueous solution and in situ oxidation of manganese hydroxide intermediate, the Mn-MOF-74 template/precursor was readily converted to MnO or δ-MnO counterpart consisting of primary nanoparticle and nanosheet building blocks, respectively, with well-retained morphology. By X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy, high-resolution TEM, N adsorption-desorption analysis and other techniques, their crystal structure, detailed morphology, and microstructure features were unambiguously revealed. Specifically, their electrochemical Li-ion insertion/extraction properties were well evaluated, and it turns out that these unique 3D microcuboids could achieve a sustained superior lithium-storage performance especially at high rates benefited from the well-orchestrated structural characteristics (MnO microcuboids: 890.7, 767.4, 560.1, and 437.1 mAh g after 400 cycles at 0.2, 0.5, 1, and 2 A g, respectively; δ-MnO microcuboids: 991.5, 660.8, 504.4, and 362.1 mAh g after 400 cycles at 0.2, 0.5, 1, and 2 A g, respectively). To our knowledge, this is the most durable high-rate capability as well as the highest reversible capacity ever reported for pure MnO anodes, which even surpass most of their hybrids. This facile, green, and economical strategy renews the traditional MOF-derived synthesis for highly tailorable functional materials and opens up new opportunities for metal-oxide electrodes with high performance.
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http://dx.doi.org/10.1021/acsami.8b00953DOI Listing
May 2018

Custom-Made Ceria Nanoparticles Show a Neuroprotective Effect by Modulating Phenotypic Polarization of the Microglia.

Angew Chem Int Ed Engl 2018 05 14;57(20):5808-5812. Epub 2018 Apr 14.

Key Laboratory of Smart Drug Delivery, Ministry of Education, School of Pharmacy, Fudan University, Shanghai, 201203, China.

The neuroprotective effect of ceria nanoparticles in the context of brain disorders has been explained by their antioxidant effect. However, the in-depth mechanism remains unknown. As resident immune cells in the brain, microglia exert a variety of functional reprogramming termed as polarization in response to stress stimuli. Herein, custom-made ceria nanoparticles were developed and found to scavenge multiple reactive oxygen species with extremely high efficiency. These nanoparticles drove microglial polarization from a pro-inflammatory phenotype to an anti-inflammatory phenotype under pathological conditions. Pretreatment of these nanoparticles changed the microglial function from detrimental to protective for the neuronal cells by blocking the pro-inflammatory signaling. This work not only helps to elucidate the mechanism of ceria-nanoparticle-mediated neuroprotection but also provides a new strategy to rebalance the immuno-environment by switching the equilibrium of the phenotypic activation of microglia.
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http://dx.doi.org/10.1002/anie.201802309DOI Listing
May 2018

Exploring the Capacity Limit: A Layered Hexacarboxylate-Based Metal-Organic Framework for Advanced Lithium Storage.

Inorg Chem 2018 Mar 27;57(6):3126-3132. Epub 2018 Feb 27.

State Key Laboratory of Precision Spectroscopy, Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science , East China Normal University , Shanghai 200062 , China.

Our previous work suggested that more carboxylate groups might lead to higher energy density for metal-organic frameworks. In this study, we synthesized a layered metal-organic framework (MOF) Ni-BHC by use of 1,2,3,4,5,6-benzenehexacarboxylic acid. After evacuation by thermal treatment, this MOF was employed as an anode for lithium storage. For its rich lithiation sites as well as layered fast-kinetics structure, it delivers a superior reversible capacity of 1261.3 mA h g at 100 mA g, far exceeding the performance of previously reported MOF-based anode materials. Density functional theory calculation and O soft X-ray absorption spectroscopy suggest that the luxuriant carboxylate-metal units play an important part in the electrochemical process.
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http://dx.doi.org/10.1021/acs.inorgchem.7b02939DOI Listing
March 2018

Understanding the Mechanical Properties and Structure Transition of Antheraea pernyi Silk Fiber Induced by Its Contraction.

Biomacromolecules 2018 06 23;19(6):1999-2006. Epub 2018 Feb 23.

State Key Laboratory of Molecular Engineering of Polymers, Laboratory of Advanced Materials and Department of Macromolecular Science , Fudan University , Shanghai 200433 , People's Republic of China.

Like most major ampullate silks of spider, the length of Antheraea pernyi silkworm silk can shrink to a certain degree when the fiber is in contact with water. However, what happens in terms of molecule chain level and how it correlates to the mechanical properties of the silk during its contraction is not yet fully understood. Here, we investigate the water-induced mechanical property changes as well as the structure transition of two kinds of A. pernyi silk fiber, which are forcibly reeled from two different individuals (silkworm a and silkworm b; the silk fiber from either one represents the lower and upper limit of the distribution of mechanical properties, respectively). The tensile test results present that most of the mechanical parameters except the post-yield modulus and breaking strain for both silk fibers have the same variation trend before and after their water contraction. Synchrotron FTIR and Raman spectra show that the native filament from silkworm a contains more α-helix structures than that in silkworm b filament, and these α-helices are partially converted to β-sheet structures after the contraction of the fibers, while the order of both β-sheet and α-helix slightly increase. On the other side, the content and orientation of both secondary structural components in silkworm b fiber keep unchanged, no matter if it is native or contracted. C CP/MAS NMR results further indicate that the α-helix/random coil to β-sheet conformational transition that occurred in the silk of silkworm a corresponds the Ala residues. Based upon these results, the detailed structure transition models of both as-reeled A. pernyi silk fibers during water contraction are proposed finally to interpret their properties transformation.
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http://dx.doi.org/10.1021/acs.biomac.7b01691DOI Listing
June 2018

Ultrathin Cobalt-Based Metal-Organic Framework Nanosheets with Both Metal and Ligand Redox Activities for Superior Lithium Storage.

Chemistry 2017 Nov 17;23(63):15984-15990. Epub 2017 Oct 17.

State Key Laboratory of Precision Spectroscopy, Shanghai Key Laboratory of Magnetic Resonance, Institute of Functional Materials, School of Physics and Materials Science, East China Normal University, Shanghai, 200062, P. R. China.

The controllable synthesis and structural tailoring of nanostructured metal-organic frameworks (MOFs) is of huge significance in boosting their potential for rechargeable batteries. We herein present the facile synthesis of cobalt-based ultrathin metal-organic framework nanosheets (referred to as "u-CoTDA") by using 2,5-thiophenedicarboxylic (H TDA) as the organic building block through a one-pot ultrasonic method for the first time. The obtained u-CoTDA exhibits high reversible capacity (790 mAh g after 400 cycles at 1 A g ) and excellent rate capability (694 mAh g at 2 A g ), which outperforms its bulk counterpart. Moreover, the detailed lithiation/delithiation processes of u-CoTDA were studied by the combination of Co K-edge X-ray absorption near edge structure (XANES), O K-edge soft X-ray spectroscopy (sXAS) and electron paramagnetic resonance (EPR) techniques, which demonstrate that both the Co centers and organic ligands of u-CoTDA are involved in the reduction/oxidation processes.
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http://dx.doi.org/10.1002/chem.201703077DOI Listing
November 2017

Ultrathin Manganese-Based Metal-Organic Framework Nanosheets: Low-Cost and Energy-Dense Lithium Storage Anodes with the Coexistence of Metal and Ligand Redox Activities.

ACS Appl Mater Interfaces 2017 Sep 25;9(35):29829-29838. Epub 2017 Aug 25.

State Key Laboratory of Precision Spectroscopy, Shanghai Key Laboratory of Magnetic Resonance, Institute of Functional Materials, School of Physics and Materials Science, East China Normal University , Shanghai 200062, P.R. China.

We herein demonstrate the fabrication of Mn- and Ni-based ultrathin metal-organic framework nanosheets with the same coordination mode (termed "Mn-UMOFNs" and "Ni-UMOFNs", respectively) through an expedient and versatile ultrasonic approach and scrutinize their electrochemical properties as anode materials for rechargeable lithium batteries for the first time. The obtained Mn-UMOFNs with structure advantages over Ni-UMOFNs (thinner nanosheets, smaller metal-ion radius, higher specific surface area) exhibit high reversible capacity (1187 mAh g at 100 mA g for 100 cycles), excellent rate capability (701 mAh g even at 2 A g), rapid Li diffusion coefficient (2.48 × 10 cm s), and a reasonable charge-discharge profile with low average operating potential at 0.4 V. On the grounds of the low-cost and environmental benignity of Mn metals and terephthalic acid linkers, our Mn-UMOFNs show alluring promise as a low-cost high-energy anode material for future LIBs. Furthermore, the lithiation-delithiation chemistry of Mn-UMOFNs was unequivocally studied by a combination of magnetic measurements, electron paramagnetic resonance, and synchrotron-based soft X-ray spectroscopy (O K-edge and Mn L-edge) experiments, the results of which substantiate that both the aromatic chelating ligands and the Mn centers participate in lithium storage.
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http://dx.doi.org/10.1021/acsami.7b09363DOI Listing
September 2017

Highly reversible lithium storage in cobalt 2,5-dioxido-1,4-benzenedicarboxylate metal-organic frameworks boosted by pseudocapacitance.

J Colloid Interface Sci 2017 Nov 18;506:365-372. Epub 2017 Jul 18.

State Key Laboratory of Precision Spectroscopy, Shanghai Key Laboratory of Magnetic Resonance, Institute of Functional Materials, School of Physics and Materials Science, East China Normal University, Shanghai 200062, PR China.

Exploiting novel metal-organic frameworks (MOFs) as electrode materials with superior rate capabilities and understanding their electrochemical behaviour in detail are crucial for boosting the application of MOFs in the field of energy storage. Herein, we prepared Co(DOBDC) (DOBDC=2,5-dioxido-1,4-benzenedicarboxylate) via a hydrothermal method and explored its electrochemical performance as an anode material for lithium-ion batteries. The as-prepared Co(DOBDC) MOF exhibits a reversible capacity of 526.1mAhg after 200 charge/discharge cycles at a current density of 500mAg and also demonstrates an impressive rate capability, with a high capacity of 408.2mAhg at a high current density of 2Ag. Furthermore, synchrotron-based soft X-ray absorption spectroscopy (sXAS) and electron paramagnetic resonance (EPR) spectroscopy have been applied to investigate the spin state of cobalt in the electrodes at different states of charge. Our results suggest that localized electrons in high-spin (S=3/2) Co in pristine Co(DOBDC) are gradually delocalized after discharging. It was also found that the high rate capability of Co(DOBDC) is mainly ascribed to an ultrafast ion intercalation pseudocapacitance process, which results from its unique microporous architecture and adequate specific surface that offers sufficient electrode/electrolyte contact and benefits fast Li ion diffusion.
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http://dx.doi.org/10.1016/j.jcis.2017.07.063DOI Listing
November 2017