Light-Assisted Li-O2 Batteries with Lowered Bias Voltages by Redox Mediators.

The enormous overpotential caused by sluggish kinetics of the oxygen reduction reaction and the oxygen evolution reaction prevents the practical application of Li-O2 batteries. The recently proposed light-assisted strategy is an effective way to improve round-trip efficiency; however, the high-potential photogenerated holes during the charge would degrade the electrolyte with side reactions and poor cycling performance. Herein, a synergistic interaction between a polyterthiophene photocatalyst and a redox mediator is employed in Li-O2 batteries. During the discharge, the voltage can be compensated by the photovoltage generated on the photoelectrode. Upon the charge with illumination, the photogenerated holes can be consumed by the oxidization of iodide ions, and thus the external circuit voltage is compensated by photogenerated electrons. Accordingly, a smaller bias voltage is needed for the semiconductor to decompose Li2 O2 , and the potential of photogenerated holes decreases. Finally, the round-trip efficiency of the battery reaches 97% with a discharge voltage of 3.10 V and a charge voltage of 3.19 V. The batteries show stable operation up to 150 cycles without increased polarization. This work provides new routes for light-assisted Li-O2 batteries with reduced overpotential and boosted efficiency.

Enzyme-Inspired Room-Temperature Lithium-Oxygen Chemistry via Reversible Cleavage and Formation of Dioxygen Bonds.

Li-O2 batteries are promising energy storage systems due to their ultra-high theoretical capacity. However, most Li-O2 batteries are based on the reduction/oxidation of Li2 O2 and involve highly reactive superoxide and peroxide species that would cause serious degradation of cathodes, especially carbon-based materials. It is important to explore lithium-oxygen reactions and find new Li-O2 chemistry which can restrict or even avoid the negative influence of superoxide/peroxide species. Here, inspired by enzyme-catalyzed oxygen reduction/oxidation reactions, we introduce a copper(I) complex 3 N-CuI (3 N=1,4,7-trimethyl-1,4,7-triazacyclononane) to Li-O2 batteries and successfully modulate the reaction pathway to a moderate one on reversible cleavage/formation of O-O bonds. This work demonstrates that the reaction pathways of Li-O2 batteries could be modulated by introducing an appropriate soluble catalyst, which is another powerful choice to construct better Li-O2 batteries.

Fabricating Ir/C Nanofiber Networks as Free-Standing Air Cathodes for Rechargeable Li-CO2 Batteries.

Li-CO2 batteries are promising energy storage systems by utilizing CO2 at the same time, though there are still some critical barriers before its practical applications such as high charging overpotential and poor cycling stability. In this work, iridium/carbon nanofibers (Ir/CNFs) are prepared via electrospinning and subsequent heat treatment, and are used as cathode catalysts for rechargeable Li-CO2 batteries. Benefitting from the unique porous network structure and the high activity of ultrasmall Ir nanoparticles, Ir/CNFs exhibit excellent CO2 reduction and evolution activities. The Li-CO2 batteries present extremely large discharge capacity, high coulombic efficiency, and long cycling life. Moreover, free-standing Ir/CNF films are used directly as air cathodes to assemble Li-CO2 batteries, which show high energy density and ultralong operation time, demonstrating great potential for practical applications.

PAN@ZIF-67-Derived "Gypsophila"-Like CNFs@Co-CoO Composite as a Cathode for Li-O2 Batteries.

CNFs@Co-CoO (CNFs = carbon nanofibers) composite showing "gypsophila"-like morphology was designed and prepared for the first time with in situ grown PAN@ZIF-67 (PAN = polyacrylonitrile) as the precursor. Benefiting from its unique morphology, hierarchically porous structure, and high-activity Co-CoO catalyst centers, the composite shows a better electrochemical performance than pure CNFs as a cathode for Li-O2 batteries.

An Extremely Simple Method for Protecting Lithium Anodes in Li-O2 Batteries.

Rechargeable Li-O2 batteries have aroused much attention for their high energy density as a promising battery technology; however, the performance of the batteries is still unsatisfactory. Lithium anodes, as one of the most important part of Li-O2 batteries, play a vital role in improving the cycle life of the batteries. Now, a very simple method is introduced to produce a protective film on lithium surface via chemical reactions between lithium metals and 1,4-dioxacyclohexane. The film is mainly composed of ethylene oxide monomers and endows Li-O2 batteries with enhanced cycling stability. The film could effectually reduce the morphology changes and suppress the parasitic reactions of lithium anodes. This simple approach provides a new strategy to protect lithium anodes in Li-O2 batteries.

Targeting cannabinoid receptor-2 pathway by phenylacetylamide suppresses the proliferation of human myeloma cells through mitotic dysregulation and cytoskeleton disruption.

Cannabinoid receptor-2 (CB2) is expressed dominantly in the immune system, especially on plasma cells. Cannabinergic ligands with CB2 selectivity emerge as a class of promising agents to treat CB2-expressing malignancies without psychotropic concerns. In this study, we found that CB2 but not CB1 was highly expressed in human multiple myeloma (MM) and primary CD138+ cells. A novel inverse agonist of CB2, phenylacetylamide but not CB1 inverse agonist SR141716, inhibited the proliferation of human MM cells (IC50 : 0.62 ∼ 2.5 µM) mediated by apoptosis induction, but exhibited minor cytotoxic effects on human normal mononuclear cells. CB2 gene silencing or pharmacological antagonism markedly attenuated phenylacetylamide's anti-MM effects. Phenylacetylamide triggered the expression of C/EBP homologous protein at the early treatment stage, followed by death receptor-5 upregulation, caspase activation, and ß-actin/tubulin degradation. Cell cycle related protein cdc25C and mitotic regulator Aurora A kinase were inactivated by phenylacetylamide treatment, leading to an increase in the ratio inactive/active cdc2 kinase. As a result, phosphorylation of CDK substrates was decreased, and the MM cell mitotic division was largely blocked by treatment. Importantly, phenylacetylamide could overcome the chemoresistance of MM cells against dexamethasone or melphalan. Thus, targeting CB2 may represent an attractive approach to treat cancers of immune origin.

The First Introduction of Graphene to Rechargeable Li-CO2 Batteries.

The utilization of the greenhouse gas CO2 in energy-storage systems is highly desirable. It is now shown that the introduction of graphene as a cathode material significantly improves the performance of Li-CO2 batteries. Such batteries display a superior discharge capacity and enhanced cycle stability. Therefore, graphene can act as an efficient cathode in Li-CO2 batteries, and it provides a novel approach for simultaneously capturing CO2 and storing energy.

Synthesis, structural characterization, and electrochemical properties of dinuclear Ni/Mn model complexes for the active site of [NiFe]-hydrogenases.

Four new dinuclear Ni/Mn model complexes RN(PPh2)2Ni(µ-SEt)2(µ-Cl)Mn(CO)3 (7, R = p-MeC6H4CH2; 8, R = EtO2CCH2) and RN(PPh2)2Ni(µ-SEt)2(µ-Br)Mn(CO)3 (9, R = p-MeC6H4CH2; 10, R = EtO2CCH2) have been prepared via the four separated step-reactions involving six new precursors RN(PPh2)2 (1, R = p-MeC6H4CH2; 2, R = EtO2CCH2), RN(PPh2)2NiCl2 (3, R = p-MeC6H4CH2; 4, R = EtO2CCH2), and RN(PPh2)2Ni(SEt)2 (5, R = p-MeC6H4CH2; 6, R = EtO2CCH2). The Et3N-assisted aminolysis of Ph2PCl with p-MeC6H4CH2NH2 or EtO2CCH2NH2·HCl in CH2Cl2 gave the azadiphosphine ligands 1 and 2 in 38% and 53% yields, whereas the coordination reaction of 1 or 2 with NiCl2·6H2O in CH2Cl2/MeOH afforded the mononuclear Ni dichloride complexes 3 and 4 in 59% and 78% yields, respectively. While thiolysis of 3 or 4 with EtSH under the assistance of Et3N in CH2Cl2 produced the mononuclear Ni dithiolate complexes 5 and 6 in 64% and 68% yields, further treatment of 5 and 6 with Mn(CO)5Cl or Mn(CO)5Br resulted in formation of the dinuclear Ni/Mn model complexes 7-10 in 31-73% yields. All the new compounds 1-10 have been structurally characterized, while model complexes 7 and 9 have been found to be catalysts for HOAc proton reduction to hydrogen under CV conditions.

Application of 5V spinel material LiNi0.5Mn1.5O4 in Li-ion batteries: single crystalline or polycrystalline?

The 5V spinel LiNi0.5Mn1.5O4 cathode materials with different morphology were prepared by a solid state calcination method and characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP), field emission scanning electron microscope (FE-SEM). Electrochemical properties of cathode material were investigated by electrochemical impedance spectroscopy (EIS), galvanostatic intermittent titration technique (GITT) and electrochemical performance tests. Compared with polycrystalline morphology (PLNMO), LiNi0.5Mn1.5O4 material with single crystalline morphology (SLNMO) proved smaller electrochemical polarization or voltage difference, lower internal resistance, faster lithium-ion diffusivity, arising from higher Mn3+ content. Differential scanning calorimetry (DSC) showed that SLNMO was more stable than PLNMO at full charged state with organic electrolyte, which exhibited initial discharge capacity of 140.2 mA h g-1 at 0.1C, coulombic efficiency of 96.1%, and specific capacity retention of 89.2% after 200 cycles at 2.5C, a little inferior to that of 91.7% for PLNMO.

Identification and characterization of human apurinic/apyrimidinic endonuclease-1 inhibitors.

The repair of abasic sites that arise in DNA from hydrolytic depurination/depyrimidination of the nitrogenous bases from the sugar-phosphate backbone and the action of DNA glycosylases on deaminated, oxidized, and alkylated bases are critical to cell survival. Apurinic/apyrimidinic endonuclease-1/redox effector factor-1 (APE-1; aka APE1/ref-1) is responsible for the initial removal of abasic lesions as part of the base excision repair pathway. Deletion of APE-1 activity is embryonic lethal in animals and is lethal in cells. Potential inhibitors of the repair function of APE-1 were identified based upon molecular modeling of the crystal structure of the APE-1 protein. We describe the characterization of several unique nanomolar inhibitors using two complementary biochemical screens. The most active molecules all contain a 2-methyl-4-amino-6,7-dioxolo-quinoline structure that is predicted from the modeling to anchor the compounds in the endonuclease site of the protein. The mechanism of action of the selected compounds was probed by fluorescence and competition studies, which indicate, in a specific case, direct interaction between the inhibitor and the active site of the protein. It is demonstrated that the inhibitors induce time-dependent increases in the accumulation of abasic sites in cells at levels that correlate with their potency to inhibit APE-1 endonuclease excision. The inhibitor molecules also potentiate by 5-fold the toxicity of a DNA methylating agent that creates abasic sites. The molecules represent a new class of APE-1 inhibitors that can be used to probe the biology of this critical enzyme and to sensitize resistant tumor cells to the cytotoxicity of clinically used DNA damaging anticancer drugs.

Biomimetic models for the active site of [Fe]hydrogenase featuring an acylmethyl(hydroxymethyl)pyridine ligand.

The first acylmethyl(hydroxymethyl)pyridine ligand-containing [Fe]hydrogenase model complexes 2-4 have been synthesized starting from the nucleophilic substitution reaction of 2-(4-MeC(6)H(4)SO(3)CH(2))-6-HOCH(2)C(5)H(3)N with Na(2)Fe(CO)(4). While the reaction course for producing complex 3 via the highly unstable intermediate complex 1 is monitored by in situ IR spectroscopy, the isolated model complexes 2-4 are fully characterized.

Redox mediators for high-performance lithium-oxygen batteries.

Aprotic lithium-oxygen (Li-O2) batteries are receiving intense research interest by virtue of their ultra-high theoretical specific energy. However, current Li-O2 batteries are suffering from severe barriers, such as sluggish reaction kinetics and undesired parasitic reactions. Recently, molecular catalysts, i.e. redox mediators (RMs), have been explored to catalyse the oxygen electrochemistry in Li-O2 batteries and are regarded as an advanced solution. To fully unlock the capability of Li-O2 batteries, an in-depth understanding of the catalytic mechanisms of RMs is necessary. In this review, we summarize the working principles of RMs and their selection criteria, highlight the recent significant progress of RMs and discuss the critical scientific and technical challenges on the design of efficient RMs for next-generation Li-O2 batteries.

Synthesis and structural characterization of some new porphyrin-fullerene dyads and their application in photoinduced H2 evolution.

The [3 + 2] cycloaddition reaction of C(60) with ethyl isonicotinoylacetate in the presence of piperidine in PhCl at room temperature or in the presence of Mn(OAc)(3) in refluxing PhCl gave the pyridyl-containing dihydrofuran-fused C(60) derivative (4-C(5)H(4)N)C(O)═C(C(60))CO(2)Et (1), whereas the phenyl-containing C(60) derivative PhC(O)═C(C(60))CO(2)Et (2) was similarly prepared by [3 + 2] cycloaddition reaction of C(60) with ethyl benzoylacetate in the presence of piperidine or Mn(OAc)(3). More interestingly, one of the new porphyrin-fullerene dyads, i.e., [4-C(5)H(4)NC(O)═C(C(60))CO(2)Et]·ZnTPPH (3, ZnTPPH = tetraphenylporphyrinozinc), could be prepared by coordination reaction of the pyridyl-containing C(60) derivative 1 with equimolar ZnTPPH in CS(2)/hexane at room temperature. In addition, the ß-keto ester-substituted porphyrin derivative H(2)TPPC(O)CH(2)CO(2)Et (4) was prepared by a sequential reaction of HO(2)CCH(2)CO(2)Et with n-BuLi in 1:2 molar ratio followed by treatment with H(2)TPPC(O)Cl in the presence of Et(3)N and then hydrolysis with diluted HCl, whereas the porphyrinozinc derivative ZnTPPC(O)CH(2)CO(2)Et (5) could be prepared by coordination reaction of 4 with Zn(OAc)(2) in refluxing CHCl(3)/MeOH. Particularly interesting is that the second new porphyrin-fullerene dyad H(2)TPPC(O)═C(C(60))CO(2)Et (6) could be prepared by [3 + 2] cycloaddition reaction of 4 with C(60) in the presence of piperidine in PhCl at room temperature. In addition, treatment of 6 with Zn(OAc)(2) in refluxing CHCl(3)/MeOH afforded the third new dyad ZnTPPC(O)═C(C(60))CO(2)Et (7). All the new compounds 1-7 were characterized by elemental analysis and various spectroscopic methods and particularly for 2, 3, and 5 by X-ray crystallography. The five-component system consisting of an electron donor EDTA, dyad 3, an electron mediator methylviologen (MV(2+)), the catalyst colloidal Pt, and a proton source HOAc was proved to be effective for photoinduced H(2) evolution. A possible pathway for such a type of H(2) evolution was proposed.

Residue preference mapping of ligand fragments in the Protein Data Bank.

The interaction between small molecules and proteins is one of the major concerns for structure-based drug design because the principles of protein-ligand interactions and molecular recognition are not thoroughly understood. Fortunately, the analysis of protein-ligand complexes in the Protein Data Bank (PDB) enables unprecedented possibilities for new insights. Herein, we applied molecule-fragmentation algorithms to split the ligands extracted from PDB crystal structures into small fragments. Subsequently, we have developed a ligand fragment and residue preference mapping (LigFrag-RPM) algorithm to map the profiles of the interactions between these fragments and the 20 proteinogenic amino acid residues. A total of 4032 fragments were generated from 71 798 PDB ligands by a ring cleavage (RC) algorithm. Among these ligand fragments, 315 unique fragments were characterized with the corresponding fragment-residue interaction profiles by counting residues close to these fragments. The interaction profiles revealed that these fragments have specific preferences for certain types of residues. The applications of these interaction profiles were also explored and evaluated in case studies, showing great potential for the study of protein-ligand interactions and drug design. Our studies demonstrated that the fragment-residue interaction profiles generated from the PDB ligand fragments can be used to detect whether these fragments are in their favorable or unfavorable environments. The algorithm for a ligand fragment and residue preference mapping (LigFrag-RPM) developed here also has the potential to guide lead chemistry modifications as well as binding residues predictions.

[Investigation on a seasonal influenza accompanying with the first locale novel A/H1N1 influenza outbreak in China].

OBJECTIVE: To timely summarize past experience and to provide more pertinent reference for control and prevention in A/H1N1 cases in influenza season. METHODS: During May 25 to 31, 2009, 2 secondary community cases caused by a influenza A/H1N1 imported case. In the close contacts of 3 A/H1N1 cases, 14 had some aspirator symptoms onset, such as fever (> or = 37.5 degrees C), cough, sore throat and etc. Laboratory tests excluded the infection of A/H1N1 influenza. For throat swab test for the 14 cases, 7 were tested for seasonal influenza virus. A face-to-face or telephone interview was conducted by CDC staff to collect information of 62 close contacts. RESULTS: Of 14 fever cases, there was no significant by differences by age[15-age group: 19.2% (5/26), over 25-age group: 25.0% (9/36); chi(2) = 0.287, P = 0.592]; by sex group [24.0% (6/25) for male and 21.6% (8/37) for female; chi(2) = 0.048, P = 0.826], by working units [dressing and design, photograph, saleroom and others, consumer group: 42.1% (8/19), 27.3% (3/11), 12.5% (2/16) and 6.3% (1/16); chi(2) = 7.653, P = 0.054], by dormitory style [dormitory style = 33.3% (4/12), non-dormitory style = 29.4% (10/34); chi(2) = 0.699, P = 0.403]. All the cases had fever (37.5 - 37.9 degrees C), no case had diarrhea. One in 3 A/H1N1 cases had diarrhea. All the 14 cases were negative result for A/H1N1 RNA. Six from 7 cases were positive for seasonal influenza test. CONCLUSION: This was a seasonal influenza outbreak happened in the close contacts of first confirmed A/H1N1 cases in community in mainland China. It showed that we should exclude the seasonal influenza in the investigation of A/H1N1 cases in the seasonal influenza period in some time. It is necessary to take effective measure to strengthen the control and prevention of seasonal influenza.

Verifying the Rechargeability of Li-CO2 Batteries on Working Cathodes of Ni Nanoparticles Highly Dispersed on N-Doped Graphene.

Li-CO2 batteries could skillfully combine the reduction of "greenhouse effect" with energy storage systems. However, Li-CO2 batteries still suffer from unsatisfactory electrochemical performances and their rechargeability is challenged. Here, it is reported that a composite of Ni nanoparticles highly dispersed on N-doped graphene (Ni-NG) with 3D porous structure, exhibits a superior discharge capacity of 17 625 mA h g-1, as the air cathode for Li-CO2 batteries. The batteries with these highly efficient cathodes could sustain 100 cycles at a cutoff capacity of 1000 mA h g-1 with low overpotentials at the current density of 100 mA g-1. Particularly, the Ni-NG cathodes allow to observe the appearance/disappearance of agglomerated Li2CO3 particles and carbon thin films directly upon discharge/charge processes. In addition, the recycle of CO2 is detected through in situ differential electrochemical mass spectrometry. This is a critical step to verify the electrochemical rechargeability of Li-CO2 batteries. Also, first-principles computations further prove that Ni nanoparticles are active sites for the reaction of Li and CO2, which could guide to design more advantageous catalysts for rechargeable Li-CO2 batteries.

Metal-CO2 Batteries on the Road: CO2 from Contamination Gas to Energy Source.

Rechargeable nonaqueous metal-air batteries attract much attention for their high theoretical energy density, especially in the last decade. However, most reported metal-air batteries are actually operated in a pure O2 atmosphere, while CO2 and moisture in ambient air can significantly impact the electrochemical performance of metal-O2 batteries. In the study of CO2 contamination on metal-O2 batteries, it has been gradually found that CO2 can be utilized as the reactant gas alone; namely, metal-CO2 batteries can work. On the other hand, investigations on CO2 fixation are in focus due to the potential threat of CO2 on global climate change, especially for its steadily increasing concentration in the atmosphere. The exploitation of CO2 in energy storage systems represents an alternative approach towards clean recycling and utilization of CO2 . Here, the aim is to provide a timely summary of recent achievements in metal-CO2 batteries, and inspire new ideas for new energy storage systems. Moreover, critical issues associated with reaction mechanisms and potential directions for future studies are discussed.

The First Example of Hetero-Triple-Walled Metal-Organic Frameworks with High Chemical Stability Constructed via Flexible Integration of Mixed Molecular Building Blocks.

An unprecedented 3D hetero-triple-walled metal-organic framework is obtained by straightforward elaboration of the mixed molecular building block (MBB) strategy. In this approach, multiple individual flexible and rigid MBBs are integrated into one composite building block as separate layers, which are of the same shape but different sizes. This MOF shows exceptional water stability and the application of Li-ion battery electrodes.

Rechargeable Li-CO2 batteries with carbon nanotubes as air cathodes.

Rechargeable Li-CO2 batteries offer great promise by combining carbon capture and energy technology. However, the discharge product Li2CO3 is difficult to decompose upon recharging. In this work, carbon nanotubes (CNTs) with high electrical conductivity and porous three-dimensional networks were firstly explored as air cathodes for rechargeable Li-CO2 batteries.