TiO2-LiF composite coating for improving NCM622 cathode cycling stability: one-step construction.

The Ni-rich NCM622 is a promising cathode material for future high energy lithium ion batteries, but unstable electrochemical performance of NCM622 hinder its large scale commercial application. The cycling peformance of nickel-rich LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode materials can be improved by surface coating. Here, a one-step approach based on TiF4 is used to successfully manufacture modified NCM622 cathode materials with a TiO2-LiF coating. The TiO2-LiF coated NCM622 preserves 79.7% capacity retention which is higher than the pure NCM622 (68.9%) at 1C after 200 cycles within 2.7-4.3 V. This material serves as the cathode for lithium-ion batteries (LIBs). The uniform TiO2-LiF coating layer can alleviate structural degradation brought on by unfavorable side reactions with the electrolyte has been validated. TiO2-LiF coated on NCM622 cathode materials can be modified easily by one-step approach.

Mechanistic insights into aggregation process of graphene oxide and bacterial cells in microbial reduction of ferrihydrite.

Microbial reduction of ferrihydrite is prevalent in natural environments and plays an important role in reductive dissolution of Fe(III) minerals. With consistent release of anthropogenic graphene oxide (GO) into water bodies, new changes in the Fe(III)-reducing microorganisms/ferrihydrite binary system demand attention. Herein, we focused on the interaction of GO and bacterial cells in view of colloidal stability and interfacial forces, and on the consequences for microbial ferrihydrite reduction. The results showed that the addition of GO decreased the bioreduction efficiency of ferrihydrite down to 1/15 of the control. Meanwhile, the GO nanosheets were found not depositing on ferrihydrite but spontaneously aggregating with Shewanella spp., the representative dissimilatory Fe(III) reduction bacterial species. Using the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory and atomic force microscopy (AFM), the aggregation process can be interpreted in three steps according to the interaction energy calculation, namely, colloidal instability, reversible aggregation and irreversible aggregation. The motility of living cells seems the reason inducing the colloidal instability between GO and bacteria. While, the aggregation remains reversible even the secondary minimum achieved at the separation distance of 8.74-9.24 nm from XDLVO. When the separation distance <5.74-6.01 nm, the adhesion work predominates and causes irreversible aggregation, validated by AFM. Additionally, the probable ecological risks raised by this aggregation behavior for the imbalance of iron biogeochemical cycle were demonstrated.

High-performance Ti-doped ZnS thin film anode for lithium-ion batteries.

Thin film microbattery is urgently needed to provide a long-term stable on-chip power for various kinds of microdevices or microsystems. Anode is a core component in thin film lithium ion microbattery, however, previous researches mostly focused on metal oxide or Si-based thin film anodes, and the reports of metal sulfide thin film anodes are limited. Herein, we present a new type of Ti-doped ZnS thin film fabricated by radio frequency (RF) magnetron co-sputtering. The Ti doping is designed to enhance the overall electrical conductivity of the ZnS thin film, since the insulation of ZnS is one of the major barriers to deliver its lithium storage performance. As an anode applied in lithium ion battery, the Ti-doped ZnS thin film exhibits good cycling stability up to 500 cycles at a current density of 1.0 A·g-1, and remains a higher specific capacity of 463.1 mAh·g-1than that of the pure ZnS thin film, showing its better electrochemical reaction reversibility. The rate capability and EIS measurements manifest the more favorable electrochemical reaction kinetics of the Ti-doped ZnS thin film, moreover, the CV tests at various scan rates indicate the improved Li+diffusion kinetics in the electrode after Ti doping.

Reductive site-selective atypical C,Z-type/N2-C2 cleavage allows C-terminal protein amidation.

Biomolecule environments can enhance chemistries with the potential to mediate and modulate self-modification (e.g., self-cleavage). While these enhanced modes are found in certain biomolecules (e.g., RNA ribozymes), it is more rare in proteins. Targeted proteolytic cleavage is vital to physiology, biotechnology, and even emerging therapy. Yet, purely chemically induced methods for the site-selective cleavage of proteins remain scarce. Here, as a proof of principle, we designed and tested a system intended to combine protein-enhanced chemistry with tag modification to enable synthetic reductive protein chemistries promoted by diboron. This reductively driven, single-electron chemistry now enables an operationally simple, site-selective cleavage protocol for proteins directed to readily accessible dehydroalanine (Dha) residues as tags under aqueous conditions and in cell lysates. In this way, a mild, efficient, enzyme-free method now allows not only precise chemical proteolysis but also simultaneous use in the removal of affinity tags and/or protein-terminus editing to create altered N- and C-termini such as protein amidation (─CONH2).

Digital Microfluidic Thermal Control Chip-Based Multichannel Immunosensor for Noninvasively Detecting Acute Myocardial Infarction.

Rapid and automated detection of acute myocardial infarction (AMI) at its developing stage is very important due to its high mortality rate. To quantitatively diagnose AMI, Myo, CK-MB, and cTnI are chosen as three biomarkers, which are usually detected through an immunosorbent assay, such as the enzyme-linked immunosorbent assay. However, the approach poses many drawbacks, such as long detection time, the cumbersome process, the need for professionals, and the difficulty of realizing automatic operation. Here, a multichannel digital microfluidic (DMF) thermal control chip integrated with a sandwich-based immunoassay strategy is proposed for the automated, rapid, and sensitive detection of AMI biomarkers. A miniaturized temperature control module is integrated on the back of the DMF chip, meeting the temperature requirement for the immunoassay. With this DMF thermal control chip, sample and reagent consumption are reduced to several microliters, significantly alleviating reagent consumption and sample dependence, and the automated and multichannel detection of biomarkers can be achieved. In this work, the simultaneously noninvasive detection of the human serum sample containing the three biomarkers of AMI is also achieved within 30 min, which improves the diagnostic accuracy of AMI. Due to the features of automation and miniaturization, the multichannel immunosensor can be used in community hospitals to increase the speed of diagnosis of patients with various acute diseases.

Two-dimensional ZnS@N-doped carbon nanoplates for complete lithium ion batteries.

Metal sulfides are promising anode materials for lithium ion batteries because of the high specific capacities and better electrochemical kinetics comparing to their oxide counterparts. In this paper, novel monocrystalline wurtzite ZnS@N-doped carbon (ZnS@N-C) nanoplates, whose morphology and phase are different from the common ZnS particles with cubic phase, are successfully synthesized. The ZnS@N-C nanoplates exhibit long cycle life with a high reversible specific capacity of 536.8 mAh · g-1after 500 cycles at a current density of 500 mA · g-1, which is superior to the pure ZnS nanoplates, illustrating the obvious effect of the N-doped carbon coating for mitigating volume change of the ZnS nanoplates and enhancing the electronic conductivity during charge/discharge processes. Furthermore, it is revealed that the ZnS single crystals with wurtzite phase in the ZnS@N-C nanoplates are transformed to the polycrystalline cubic phase ZnS after charge/discharge processes. In particular, the ZnS@N-C nanoplates are combined with the commercial LiNi0.6Co0.2Mn0.2O2cathode to fabricate a new type of LiNi0.6Co0.2Mn0.2O2/ZnS@N-C complete battery, which exhibits good cycling durability up to 120 cycles at a charge/discharge rate of 1 C after the prelithiation treatment on the ZnS@N-C anode, highlighting the potential of the ZnS@N-C nanoplates anode material applied in lithium ion battery.

LanCLs add glutathione to dehydroamino acids generated at phosphorylated sites in the proteome.

Enzyme-mediated damage repair or mitigation, while common for nucleic acids, is rare for proteins. Examples of protein damage are elimination of phosphorylated Ser/Thr to dehydroalanine/dehydrobutyrine (Dha/Dhb) in pathogenesis and aging. Bacterial LanC enzymes use Dha/Dhb to form carbon-sulfur linkages in antimicrobial peptides, but the functions of eukaryotic LanC-like (LanCL) counterparts are unknown. We show that LanCLs catalyze the addition of glutathione to Dha/Dhb in proteins, driving irreversible C-glutathionylation. Chemo-enzymatic methods were developed to site-selectively incorporate Dha/Dhb at phospho-regulated sites in kinases. In human MAPK-MEK1, such "elimination damage" generated aberrantly activated kinases, which were deactivated by LanCL-mediated C-glutathionylation. Surveys of endogenous proteins bearing damage from elimination (the eliminylome) also suggest it is a source of electrophilic reactivity. LanCLs thus remove these reactive electrophiles and their potentially dysregulatory effects from the proteome. As knockout of LanCL in mice can result in premature death, repair of this kind of protein damage appears important physiologically.

Interfacial Mechanical Strength Enhancement for High-Performance ZnS Thin-Film Anodes.

Thin-film lithium-ion microbatteries with a high energy density and long lifespan are exceedingly desired for developing self-powered integrated micro-nano devices and systems. However, exploring high-performance thin-film anodes still remains a challenge. Herein, a double-layer-structure diamond-like carbon-ZnS (DLC-ZnS) thin-film anode fabricated by radio frequency magnetron sputtering exhibits high specific capacity and good cycling stability up to 1000 cycles, superior to the pure ZnS thin-film anode. To understand the mechanism, the bimodal amplitude modulated-frequency modulated atomic force microscopy was used to explore the mechanical properties of the thin films, and the DLC layer shows significantly higher Young's modulus than the ZnS thin film. The DLC interface with a high Young's modulus can effectively buffer the mechanical stress originating from the huge volume changes of the ZnS layer during lithiation/delithiation processes; therefore, the DLC interface maintains the higher mechanical integrity of the DLC-ZnS thin film and improves the utilization of ZnS. In addition, the electrochemical kinetics of the DLC-ZnS and ZnS thin films were also investigated by electrochemical methods. Electrochemical impedance spectroscopy tests indicate the obstacle of the DLC interface to Li+ ion diffusion in the initial charge/discharge processes; however, the DLC-ZnS thin film exhibits lower total resistance than the ZnS thin film afterward. In particular, galvanostatic intermittent titration technique tests were performed to find out the differences between the two thin films during the galvanostatical charge/discharge processes. The results demonstrate the obviously enhanced conversion reaction reversibility and decreased alloy reaction polarization of the DLC-ZnS thin film; therefore, it delivers higher reversible capacity.

Interaction between Biocompatible Graphene Oxide and Live Shewanella in the Self-Assembled Hydrogel: The Role of Physicochemical Properties.

Understanding the interaction of graphene materials with bacterial cells is crucial for exploiting their environmental applications. Meanwhile, knowledge on the mechanism of graphene oxide (GO) action to bacteria is still incomplete. This study focused on the inter-relationship of biocompatible GO and the well-known dissimilatory metal-reducing bacteria Shewanella, in view of the biographene hydrogel (BGH), a self-assembly of GO and live bacteria. The results showed that, among various inter-related physicochemical properties of GO, the sheet area determined the bacterial survival and the gelation potential with the same Shewanella strain. For the biocompatible GO sheet above 0.30 µm2, the larger the GO, the higher the speed of BGH assembling. Only 22 h was needed to obtain BGH using GO with an average area of 1.83 µm2 (maximum in this study). The GO oxidation degree was found to be another critical factor affecting whether BGH formed or not, with a referential threshold of C/O > 1.75. Finally, surface force of GO was detected and correlated with the bacterial adhesion behavior for the first time, confirming that the large GO in the low oxidation state has high resultant force to attract bacteria. All these findings pave a promising way to develop a GO-bacteria complex like BGH to treat industrial wastewater in the future.

Binder-free C@NiCo2O4 on Ni foam with ultra-stable pseudocapacitive lithium ion storage.

Carbon-coated nickel cobaltate on nickel foam (C@NCO@NF) with stable pseudocapacitive lithium storage capacity was prepared via a two-step strategy. NiCo hydroxide was initially grown on Ni foam via electrodeposition. Subsequent glucose soaking and annealing converted the intermediate into C@NCO@NF. Carbon coating could significantly improve the cycling stability and rate performance of the binder-free anode. The C@NCO@NF electrode could stably deliver a reversible capacity of 513 mAh · g-1 after 500 cycles at a current density of 500 mA · g-1. It could even stably cycle at a high current density of 5000 mA · g-1 for 3000 cycles, with a reversible capacity of 115 mAh · g-1. Kinetic analysis revealed that surface-controlled pseudocapacitance plays a dominant role in the lithium ion storage. Improved electrochemical performance is attributed to the synergetic effect of pseudocapacitance and carbon coating.

MoPer1 is required for growth, conidiogenesis, and pathogenicity in Magnaporthe oryzae.

BACKGROUND: GPI-anchoring is a prevalent Glycosylphosphatidylinositol modification process of posttranslational protein and is necessary for cell wall integrity in eukaryotes. To date, the function of GPI anchored-related protein remains unknown in phytopathogenic fungi. RESULTS: We here characterized the functions of MoPer1, a homolog of Saccharomyces cerevisiae ScPer1, from the rice blast fungus Magnaporthe oryzae. Transcriptional analysis demonstrated that MoPER1 was significantly upregulated during conidiation and infection. We found that the ∆Moper1 mutant was defective in conidiation and appressoria formation, and MoPer1 was involved in osmotic stress response and maintaining the cell wall integrity. Pathogenicity assays indicated that deletion of MoPEP1 significant reduction in virulence. Microscopic examination of the lesions revealed that the invasive hyphae of ∆Moper1 mutants were mostly restricted to the primary infected leaf sheath cells. CONCLUSIONS: Our results indicated that MoPer1 is necessary for growth, conidiogenesis, and pathogenicity of the fungus. Our study facilitated to deep elucidate the pathogenic molecular mechanism of M. oryzae, and also provided a very helpful reference value for developing effective fungicide pointed at as the gene for target.

Ultrafine Mo-doped SnO2 nanostructure and derivative Mo-doped Sn/C nanofibers for high-performance lithium-ion batteries.

Tin-based materials have been intensively studied as attractive candidates for high-capacity and long-cycle-life anodes in Li-ion batteries (LIBs) owing to their low cost and high energy density. However, they all suffer from severe structural decay during the lithium ion insertion/extraction process, which results in deterioration in the overall performance of the batteries. To mitigate this problem, we have synthesized a Mo-doped SnO2 nanostructure via a facile hydrothermal method, which then fragmented into ultrafine particles after dozens of cycles. The fracture-resistant size and ample contact with Super-P and Li2O greatly improved the electrochemical kinetics and cyclability to deliver a reversible capacity of 670 mA h g-1 after 700 cycles, which demonstrated the potential suitability of Mo-doped SnO2 nanoparticles as a long-cycle-life anode material. Then, the compounds were uniformly dispersed in carbon nanofibers and reduced in situ to prepare a free-standing anode via electrospinning and carbonization. When used directly as an anode in LIBs (without a polymeric binder or conductive agent, as well as a current collector), the nanofiber membrane anode delivered comparable cycling performance and capacity to that of a slurry-coated electrode.

Metal-binding properties of an Hpn-like histidine-rich protein.

The Hpn-like protein (Hpnl), a histidine- and glutamine-rich protein, is critical for Helicobacter pylori colonization in human gastric muscosa. In this study, the thermodynamic properties of Ni(II), Cu(II), Co(II), and Zn(II) toward Hpnl were studied by isothermal titration calorimetry (ITC). We found that Hpnl exhibits two independent binding sites for Ni(II) as opposed to one site for Cu(II), Co(II), and Zn(II). Protease digestion and chemical denaturation analysis further revealed that Ni(II) confers a higher stability upon Hpnl than other divalent metal ions. The potential Ni(II) binding sites are localized in the His-rich domain of Hpnl as confirmed by mutagenesis in combination with modification of histidine residues of the protein. We also demonstrated that the single mutants (H29A and H31A) and tetrameric mutant (H29-32A) cut nearly half of the binding capacity of Hpnl towards nickel ions, whereas other histidine residues (His30, 32, 38, 39, 40, and 41) are nonessential for nickel coordination. Escherichia coli cells that harbored H29A, H31A, and H29-32A mutant genes exhibited less tolerance toward high concentrations of extracellular nickel ions than those with the wild-type gene. Our combined data indicated that the conserved histidine residues, His29 and His31 in the His-rich domain of Hpnl, are critical for nickel binding, and such a binding is important for Hpnl protein to fulfill its biological functions.

Polymeric architectures of bismuth citrate based on dimeric building blocks.

Four bismuth complexes, (H2En)[Bi2(cit)2(H2O)4/3]·(H2O) x (1), (H2En)3[Bi2(cit)2Cl4]·(H2O) x (2), (HPy)2[Bi2(cit)2(H2O)8/5]·(H2O) x (3) and (H2En)[Bi2(cit)2](H2O) x (4) [cit = citrate4-; En = ethylenediamine; Py = pyridine] have been synthesized and crystallized. The crystal structures reveal that the basic building blocks in all of these complexes are bismuth citrate dimeric units which combine to form polymeric architectures. The embedded protonated ethylenediamine and pyridine moieties in the polymeric frameworks have been identified by X-ray crystallography and solid-state cross polarization/magic angle spinning (CP/MAS) 13C NMR. Based on the framework of complex 1, a structural model of a clinically used antiulcer drug, ranitidine bismuth citrate (RBC) was generated. The behavior of the protonated amine-bismuth citrate complexes in acidic aqueous solution has been studied by electrospray ionization-mass spectrometry (ESI-MS). ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.1007/s11426-010-4113-x and is accessible for authorized users.

Binding of Ni2+ to a histidine- and glutamine-rich protein, Hpn-like.

Hpn-like (Hpnl) protein, encoded by the hpnl gene in Helicobacter pylori and featuring a histidine-rich and two glutamine-rich motifs, can render nickel tolerance to H. pylori when the external nickel level reaches toxic limits. We found that the recombinant Hpnl exists as an oligomer in the native state and binds to two molar equivalents of nickel ions per monomer with a dissociation constant of 3.8 microM. Nickel could be released from Hpnl either at acidic pH (pH(1/2) 4.6) or in the presence of chelate ligands, such as EDTA (t(1/2) = 220, 355, and 716 min at pH 6.0, 7.0, and 7.5, respectively). Our combined spectroscopic data show that nickel ion coordinates to a nitrogen of a histidine residue possibly with a coordination number of four (square-planar geometry) or five. The growth of Escherichia coli cells with or without the hpnl gene implied a protective role of Hpnl under higher concentrations of external nickel ions. Hpnl may serve a role in binding/storage or detoxification of excess nickel ions.

Inhibition of urease by bismuth(III): implications for the mechanism of action of bismuth drugs.

Bismuth compounds are widely used for the treatment of peptic ulcers and Helicobacter pylori infections. It has been suggested that enzyme inhibition plays an important role in the antibacterial activity of bismuth towards this bacterium. Urease, an enzyme that converts urea into ammonia and carbonic acid, is crucial for colonization of the acidic environment of the stomach by H. pylori. Here, we show that three bismuth complexes exhibit distinct mechanisms of urease inhibition, with some differences dependent on the source of the enzyme. Bi(EDTA) and Bi(Cys)(3) are competitive inhibitors of jack bean urease with K(i) values of 1.74 +/- 0.14 and 1.84 +/- 0.15 mM, while the anti-ulcer drug, ranitidine bismuth citrate (RBC) is a non-competitive inhibitor with a K (i) value of 1.17 +/- 0.09 mM. A (13)C NMR study showed that Bi(Cys)(3) reacts with jack bean urease during a 30 min incubation, releasing free cysteines from the metal complex. Upon incubation with Bi(EDTA) and RBC, the number of accessible cysteine residues in the homohexameric plant enzyme decreased by 5.80 +/- 0.17 and 11.94 +/- 0.13, respectively, after 3 h of reaction with dithiobis(2-nitrobenzoic acid). Kinetic analysis showed that Bi(EDTA) is both a competitive inhibitor and a time-dependent inactivator of the recombinant Klebsiella aerogenes urease. The active C319A mutant of the bacterial enzyme displays a significantly reduced sensitivity toward inactivation by Bi(EDTA) compared with the wild-type enzyme, consistent with binding of Bi(3+) to the active site cysteine (Cys(319)) as the mechanism of enzyme inactivation.

Synthesis, characterization and DNA-binding properties of La(III) complex of chrysin.

A novel La(III) complex of chrysin (5,7-dihydroxyflavone) was synthesized and characterized by UV, IR, 1H NMR, thermogravimetry/differential thermal analysis (TG/DTA) and elementary analyses. The interactions of the La(III) complex and chrysin with calf thymus DNA were investigated by spectrophotometric methods and viscosity measurements. The intrinsic binding constants of La(III) complex and chrysin are 1.29 x 10(6) and 5.44 x 10(5) M(-1), respectively. Experimental results indicated that La(III) complex and chrysin can both bind to DNA by intercalation modes, but the binding affinity of La(III) complex is much higher than that of chrysin. Comparative antitumor activities of La(III) complex and chrysin were tested by MTT and SRB methods. The results show that at the concentration of 10 microM for chrysin and La(III) complex, the inhibitory ratios of La(III) complex against the tested tumor cells were higher than those of chrysin.

Application of artificial neural networks in multivariable optimization of an on-line microwave FIA system for catalytic kinetic determination of iridium(III).

A new rapid, selective and sensitive on-line microwave flow injection-kinetic method was developed for spectrophotometric determination of micro amounts of Ir(III), based on its catalytic effect on the m-acetylchlorophosphonazo (CPA-mA) and KIO(4) reaction in NaOH media. An on-line microwave oven was employed to accelerate the reaction. The reaction was followed spectrophotometrically by measuring the decrease of the absorbance of CPA-mA at 580 nm. The effect of five variables for the determination of Ir(III) was optimized by means of a multilayer artificial neural network using extended delta-bar-delta (EDBD) algorithms. Under the optimum experimental conditions, Ir(III) could be determined in the range 0.060-0.60 micro gZZZ;mL(-1) with detection limit of 0.02 micro gZZZ;mL(-1) and the sampling frequency of 34 h(-1). The proposed method was applied to the determination of micro amounts of Ir(III) in refined ore and secondary alloy with the recoveries from 91.4% to 109%.