Vanadium-based polyanionic compounds as cathode materials for sodium-ion batteries:Toward high-energy and high-power applications

Sodium ion batteries(SIBs)have been regarded as one of the alternatives to lithium ion batteries owing to their wide availability and significantly low cost of sodium sources.However,they face serious challenges of low energy&power density and short cycling lifespan owing to the heavy mass and large radius of Na⁺.Vanadium-based polyanionic compounds have advantageous characteristic of high operating voltage,high ionic conductivity and robust structural framework,which is conducive to their high energy&power density and long lifespan for SIBs.In this review,we will overview the latest V-based polyanionic compounds,along with the respective characteristic from the intrinsic crystal structure to performance presentation and improvement for SIBs.One of the most important aspect is to discover the essential problems existed in the present V-based polyanionic compounds for high-energy&power applications,and point out most suitable solutions from the crystal structure modulation,interface tailoring and electrode configuration design.Moreover,some scientific issues of V-based polyanionic compounds shall be also proposed and related future direction shall be provided.We believe that this review can serve as a motivation for further development of novel V-based polyanionic compounds and drive them toward high energy&power applications in the near future.     

Total synthesis of TRADD death domain with arginine N-GlcNAcylation by hydrazide-based native chemical ligation

TNFR1-associated death domain protein(TRADD)with arginine N-GlcNAcylation is a novel and structurally unique posttranslational modification(PTM)glycoprotein that blocks the formation of death-inducing signaling complex(DISC),orchestrating host nuclear factorκB(NF-κB)signaling in entero-pathogenic Escherichia coli(EPEC)-infected cells.This particular glycosylated modification plays an extremely vital role for the effective colonization and pathogenesis of pathogens in the gut.Herein we describe the total synthesis of TRADD death domain(residues 195-312)with arginine235 NGlcNAcylation(Arg-GIcNAc TRADD(195-312)).Two longish peptidyl fragments of the wild-type primary sequence were obtained by robust,microwave-assisted,highly efficient,solid-phase peptide synthesis(SPPS),the N-GlcNAcylated sector was built by total synthesis and attached specifically to resinbound peptide with an unprotected ornithine residue via silver-promoted on-resin guanidinylation,ArgGlcNAc TRADD(195-312)was constructed by hydrazide-based native chemical ligation(NCL).The facile synthetic strategy is expected to be generally applicable for the rapid synthesis of other proteins with Arg-GIcNAc modification and to pave the way for the related chemically biological study.     

Steam activation of Fe-N-C catalyst for advanced power performance of alkaline hydrazine fuel cells

Alkaline hydrazine liquid fuel cells(AHFC) have been highlighted in terms of high power performance with non-precious metal catalysts.Although Fe-N-C is a promising non-Pt electrocatalyst for oxygen reduction reaction(ORR),the surface density of the active site is very low and the catalyst layer should be thick to acquire the necessary number of catalytic active sites.With this thick catalyst layer,it is important to have an optimum pore structure for effective reactant conveyance to active sites and an interface structure for faster charge transfer.Herein,we prepare a Fe-N-C catalyst with magnetite particles and hierarchical pore structure by steam activation.The steam activation process significantly improves the power performance of the AHFC as indicated by the lower IR and activation voltage losses.Based on a systematic characterization,we found that hierarchical pore structures improve the catalyst utilization efficiency of the AHFCs,and magnetite nanoparticles act as surface modifiers to reduce the interracial resistance between the electrode and the ion-exchange membrane.     

Combined QSAR/QSPR,Molecular Docking,and Molecular Dynamics Study of Environmentally Friendly PBDEs with Improved Insulating Properties

To improve the insulating properties of polybrominated diphenyl ethers(PBDEs), we studied the molecular structures and energy gap(Eg) values of 209 PBDEs using a three-dimensional quantitative structure-activity relationship(3D-QSAR) model, molecular docking, and molecular dynamics. We also analyzed the interaction mechanisms of PBDEs using a 2D-QSAR model, molecular substitution characteristics, and molecular docking. The 3D-QSAR model showed that the 2-, 4-, 5-, and 6-positions significantly influenced the PBDE insulating properties. Using BDE-34 as a template molecule, we designed six derivatives with 0.47%-28.44% higher insulation tlian BDE-34. Compared with BDE-34, the stability and flame retardancy of the above six derivatives were not adversely affected. These derivatives, except for 2,6-cyanomethyl-BDE, 2-cyanomethyl-BDE, and 2-aniinomethyl-BDE, were more toxic and biodegradable than BDE-34, but showed weaker bioaccumulation and migration abilities than BDE-34. Mechanism analysis showed that the highest occupied orbital energy, the most negative charge, and the dipole moment were the main quantitative parameters that aflected the PBDE insulating properties. PBDE insulation gradually decreased as the number of Br atoms increased. The level of similarity between the substitution patterns on the two benzene rings was significantly correlated with PBDE insulation, with hydrophobic groups having a more significant efiect on PBDE insulation.     

Novel fusiform core-shell-MOF derived in tact metal@carb on composite:An efficient cathode catalyst for aqueous and solid-state Zn-air batteries

Owing to the varied mechanisms of ORR/OER,exploiting cost-effective bifunctional catalysts with robust ORR/OER activities and excellent performances in Zn-air batteries is still a challenge.In this work,the Co/CoO@NSC bifunctional catalyst is obtained by using Zn-MOF@Co-MOF as self-template.The Co/CoO@NSC composite has interconnected porous architecture with in tact metal@carb on structure,exhibiting superior electrocatalytic activities toward ORR and OER that can be comparable with the Pt/C and RuO₂ catalysts,respectively.The Co/CoO@NSC-based aqueous Zn-air battery achieves a high specific capacity(759.7 mAh/g)and energy density(990.5 Wh/kg),and ultra-long rechargeable property(more than 400 h/1200 cycles).The Co/CoO@NSC-based solid-state Zn-air battery also delivers an excellent performance with a long cycle life(more than 143 h/858 cycles).Most importantly,the newly synthesized and recharged Co/CoO@NSC-based solid-state Zn-air battery can be used to light up a 2 V LED lamp for more than 28 h,demonstrating the superior practicability as rechargeable power source.     

Ultra-small nanodots coated with oligopeptides providing highly negative charges to enhance osteogenic differentiation of hBMSCs better than osteogenic induction medium

For bone regenerative engineering,it is a promising method to form skeletal tissues differentiating from human bone morrow mesenchyme stem cells(hBMSCs).However,it is still a critical challenge to efficiently control ostogenesis and clearly reveal the influence factor.To this end,the fluorescent gold nanodots(Au NDs) with highly negative charges as osteogenic induction reagent are successfully synthesized,which display better than commercial osteogenic induction medium through the investigations of ALP activity(2.5 folds) and cytoskeleton staining(1.5 folds).Two kinds of oligopeptides with different bio-structures(cysteine,Cys and glutathione,GSH) are selected for providing surficial charges on Au NDs.It is revealed that Au-Cys with more negative charges(-51 mV) play better role than Au-GSH(-19 mV) in osteogenic differentiation,when both of them have same size(~2 nm),sphere shape and show similar cell uptake amount.To explore deeply,osteogenesis related signaling pathways are monitored,revealing that the enhancement of osteogenic differentiation was through autophagy signaling pathway triggered by Au-Cys.And the promotion of highly negative charges in osteogenic diffe rentiation was further proved via sliver nanodots(Ag NDs,Ag-Cys and Ag-GSH) and carbon nanodots(CDs,Cys-CDs and GSH-CDs).This work indicates part of insights during hBMSCs differentiation and provides a novel strategy in osteogenic differentiation process.     

Miniaturized electrochemical sensors and their point-of-care applications

Most of the current analytical methods depend largely on laboratory-based analytical techniques that require expensive and bullky equipment,potentially incur costly testing,and involve lengthy detection processes.With increasing requirements for point-of-care testing(POCT),more attention has been paid to miniaturized analytical devices.Miniaturized electrochemical(MEC)sensors,including different material-based MEC sensors(such as DNA-,paper-,and screen electrode-based),have been in strong demand in analytical science due to their easy operation,portability,high sensitivity,as well as their short analysis time.They have been applied for the detection of trace amounts of target through measuring changes in electrochemical signal,such as current,voltage,potential,or impedance,due to the oxidation/reduction of chemical/biological molecules with the help of electrodes and electrochemical units.MEC sensors present great potential for the detection of targets including small organic molecules,metal ions,and biomolecules.In recent years,MEC sensors have been broadly applied to POCT in various fields,including health care,food safety,and environmental monitoring,owing to the excellent advantages of electrochemical(EC)technologies.This review summarized the state-of-the-art advancements on various types of MEC sensors and their applications in POCT.Furthermore,the future perspectives,opportunities,and challenges in this field are also discussed.     

Recent progress of thin-film photovoltaics for indoor application

Indoor photovoltaics have attracted increasing attentions owing to their great potential in supplying energy for low power devices under indoor light in our daily life.The third generation thin-film solar cells,including dye-sensitized solar cells,perovskite solar cells and organic solar cells,have made rapid progress from the aspect of materials design to photovoltaic performance.This review provides an overview on the recent advances in the development of indoor photovoltaic technologies based on the third generation solar cells.The design principles of advanced thin-film indoor photovoltaics were also summarized according to the characteristics of indoor light and the advantages of the third generation solar cells.Finally,after summarizing the current research progress,the perspective on this topic is provided.     

C-S coupling with nitro group as leaving group via simple inorganic salt catalysis

An efficient and practical synthetic protocol to synthesize nonsymmetrical aryl thioethers by nucleophilic aromatic substitution(S_NAr)reaction of nitroarenes by thiols with potassium phosphate as the catalyst is described.Various moderate to strong electron-withdrawing functional groups are tolerated by the system to provide thioethers in a good to excellent yields.We also showed that the present method allows access to 3 drug examples in a short reaction time.Finally,mechanistic studies suggest that the reaction may form the classic Meisenheimer complex through a two-step additionelimination mechanism.     

Visualizing phase transition of upper critical solution temperature (UCST) polymers with AIE

The stimuli-responsive polymers with upper critical solution temperatures(UCST) are highly attractive for drug delivery applications. However, the phase transition process of UCST polymer is usually characterized by turbidity measurement and electron microscopy, which are significantly restricted by low sensitivity and static observation. In contrary, the fluorescence technique has significant advantages in terms of high sensitivity, easy operation, and dynamic observation. However, the conventional fluorophores suffer from the drawbacks of aggregation-caused quenching(ACQ) after being encapsulated by UCST polymers, which are not suitable for direct visualization of the phase transition process. To tackle this challenge, we herein developed a series of UCST polymers based on polyacrylamides decorated with bile acid and aggregation-induced emission(AIE)-active tetraphenylethene(TPE) groups, which can be used for direct fluorescence monitoring of the phase transition process. Moreover, the AIE-active UCST polymers can serve as drug carriers, which can not only monitor the drug release process under thermal stimuli, but also verify the drug release by fluorescence recovery after thermal stimuli. It is expected that the AIE-active UCST polymers with self-monitoring ability are promising for biomedical applications.     

硫逐磷酸酯和二硫代磷酸酯的电喷雾电离质谱lectrosprayIon

研究了9种硫逐磷酸酯及二硫代磷酸酯的电喷雾电离 (ESI)质谱并归纳了谱图特征。根据碰撞诱导解离 (CID)的结果 ,讨论了其在ESI质谱的规律。     

有机锡化合物的电喷雾电离质谱

报道了一系列有机锡ＲＲＰ（Ｓ）ＳＳｎ（Ｃｙ）３化合物的电喷雾电离质谱（ＥＳＩ－ＭＳ）及碰撞诱导解离质谱（ＣＩＤ－ＭＳ）,总结了其谱图特征,讨论了其碎裂机理,为该类化合物的鉴定提供了依据。     

Electron-impact induced oxygen migration in the mass spectra of β-ketoalkylidenephosphoranes

The mass spectra of six β-ketoalkylidenephosphoranes have been examined. The spectra all exhibit an electron-impact induced migration of oxygen to phosphorus reminiscent of their thermal decomposition.     

Letter: intercluster chemistry of protonated and sodiated betaine dimers upon collision induced dissociation and electron induced dissociation

The collision induced dissociation and electron induced dissociation spectra of the [2M + H](+) and [2M + Na](+) clusters of the zwitterionic amino acid, betaine (M), have been examined in a hybrid linear ion trap Fourier transform ion cyclotron resonance mass spectrometer. Intercluster reactions are observed in the collision induced dissociation spectra of [2M + H](+) and [2M + Na](+) and in the electron induced dissociation spectrum of [2M + H](+).     

Aromatic Fused [30] Heteroannulenes with NIR Absorption and NIR Emission: Synthesis,Characterization, and Excited‐State Dynamics

Two hitherto unknown planar aromatic [30] fused heterocyclic macrocycles (1.1.0.1.1.0), with NIR absorption in free‐base form and protonation‐induced enhanced NIR emission, have been synthesized from easy to make precursors. The induced correspondence of fusion on the macrocyclic structure, electronic absorption, and emission spectra have been highlighted.     

Electronic spectra of adenine and guanine: Assignments and effects of solution environment

The results obtained by us on the ultraviolet absorption and fluorescence spectra of adenine and guanine and partially those of 8-azaguanine and 8-bromoguanine have been discussed and interpreted with the help of molecular orbital calculations. Effects of oxygenation and nitrogenation on the spectra and possible tautomerisations of molecules induced by oxygen and UV irradiation have mainly been the subjects of interest. Oscillations observed in the absorption spectra of guanine in aqueous solutions under UV irradiation have been interpreted in terms of the tautomerisation of the molecule following its slow complexation with the dissolved oxygen. This complexation of oxygen with guanine in DNA may cause lethal damage to biological systems including carcinogenesis.     

The modern mass spectrometer—a complete chemical laboratory

Using nitrobenzene as an example, various ways in which a contemporary mass spectrometer can be utilized to yield a wealth of information about the compound studied are reviewed. Applying a variety of different techniques and procedures, in addition to the conventional low resolution mass spectrum, the following nitrobenzene spectra have been obtained: collision induced dissociation mass spectrum, mass analysed ion kinetic energy spectra, collision induced dissociation mass analysed ion kinetic energy spectra, spectra obtained at constant B/E, spectra obtained at constant B²/E, high voltage scans of metastable ion fragmentation processes, consecutive fragmentations in different field free regions, charge exchange mass spectra, charge stripping mass spectra, doubly charged ion mass spectra, chemical ionization mass spectra, negative ion mass spectra, negative ion mass analysed ion kinetic energy spectra, negative ion mass analysed ion kinetic energy collision induced dissociation spectra, charge inversion spectra, etc. The complementary types of information available from the above studies are discussed to show the unique versatility of mass spectrometry as a technique for the examination of organic compounds.     

The infrared spectra (500–140 cm−1) of some diazine complexes of first transition series metal(II) ions

Thirty complexes of some diazines, i.e. pyrazine, pyrimidine and pyridazine, with metal(II) ions of the first transition series have been prepared and their infrared spectra determined. Assignments for metal-ligand modes are proposed on the basis of the band shifts induced by deuteration of pyrazine and by the effects of metal ion and halide substitution. The structural implications of the spectra are discussed.     

Redox dependent conformational changes in the mixed valence form of the cytochrome c oxidase from p. The reorganization of glutamic acid 278 is coupled to the electron transfer from/to heme a and the binuclear center. denitrificans

In this work we present the separation of FTIR difference signals induced by electron transfer to/from the redox centers of the cytochrome c oxidase from P. denitrificans and compare electrochemically induced FTIR difference spectra with those induced by CO photolysis. FTIR difference spectra of rebinding of CO to the half reduced (mixed valence) form of the cytochrome c oxidase after photolysis reflect the conformational changes induced by the rebinding of CO and by electron transfer reactions from heme a3 to heme a and further on to CUA. During this process, heme a3 (and CUB) are oxidized, whereas heme a and CuA are reduced. By subtracting these difference spectra from an electrochemically induced FTIR difference spectrum, where all four cofactors are reduced, the contributions for heme a3 (and CuB) could be separated. Correspondingly, the spectral contributions of heme a and CuA have been separated. The comparison of these spectra with the spectra calculated for the hemes on the basis of their redox dependent changes previously published in Hellwig et al., (Biochemistry 38, (1999) 1685-1694) show a high degree of similarity, except for additional signals coupled to the reorganization of the binuclear center upon CO rebinding. The separated spectra clearly show that the signals attributed to Glu278, an amino acid discussed to be crucial for proton pumping, is coupled to electron transfer to/from heme a and the binuclear heme a3-CuB center.     

Thioflavin T: Electronic Circular Dichroism and Circularly Polarized Luminescence Induced by Amyloid Fibrils

The circularly polarized luminescence (CPL) spectrum of thioflavin T (ThT) bound to insulin amyloid fibrils has been measured for the first time. It has been found that the samples exhibiting induced circular dichroism (CD) retain the optical activity in the CPL spectra, with the same sign of the rotatory strength. The fluorescence dissymmetry factor is substantial (of the order of magnitude 10^?2). Unlike in the corresponding CD and absorption spectra, there is no shift of the CPL band with respect to the fluorescence band. It has been verified that the measured CPL spectra are free from artifacts from circularly polarized scattering of emitted light by conducting additional measurements in a medium with a refractive index similar to insulin (methylsalicylate). The CD and CPL spectra have been interpreted by means of density functional calculations carried out for ThT in its ground and first excited states in different dielectric environments and for ThT interacting with an aromatic ring. It has been found that the presence of an aromatic ring close to the ThT molecule induces Cotton effects of the same order of magnitude as the stabilization of one enantiomeric conformer. Thus, it is expected that both mechanisms contribute to the induced CD and CPL effect to a similar degree.