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ABSTRACT: In this paper, a C-F bond activation reaction of a chloro-bridged iridium(iii) dimer (dfppy)(2)Ir(μ-Cl)(2)Ir(dfppy)(2) () (dfppy denotes 2-(4,6-difluorophenyl)pyridyl) in the presence of sodium methoxide has been reported, leading to the formation of a heteroleptic cyclometalated iridium(iii) fluorophenylpyridine complex . HPLC-mass analysis confirmed the release of formaldehyde in the product mixture. When sodium benzyloxide was used as the base, complex was also generated with the release of a benzaldehyde derivative. Complex has been fully characterized by (1)H-NMR, (19)F-NMR and X-ray crystallographic methods, confirming the partial loss of one of the fluorine atoms on one of the cyclometalated phenylpyridyl ligands. Photophysical studies of complex show that it has a similar absorption spectrum to that of Ir(iii)(dfppy)(3). However, the emission spectrum shows a red shift maximum emission band at 478 nm due to the loss of a single fluorine atom, highlighting the critical effect of fluorine on the photoluminescence of these Ir(iii) complexes. Finally, intensive mechanistic studies including HPLC-mass analysis, (1)H-NMR, and (19)F-NMR studies demonstrate that the formation of complex should involve a critical β-hydride elimination of Ir(iii)-alkoxide intermediate and the participation of Ir-hydride and/or Ir-fluoride intermediates.
Dalton Transactions 01/2013; · 3.84 Impact Factor
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ABSTRACT: We present decentralized rollout sampling policy iteration (DecRSPI) - a new
algorithm for multi-agent decision problems formalized as DEC-POMDPs. DecRSPI
is designed to improve scalability and tackle problems that lack an explicit
model. The algorithm uses Monte- Carlo methods to generate a sample of
reachable belief states. Then it computes a joint policy for each belief state
based on the rollout estimations. A new policy representation allows us to
represent solutions compactly. The key benefits of the algorithm are its linear
time complexity over the number of agents, its bounded memory usage and good
solution quality. It can solve larger problems that are intractable for
existing planning algorithms. Experimental results confirm the effectiveness
and scalability of the approach.
03/2012;
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ABSTRACT: In the title compound, [Ir(C(11)H(6)F(2)N)(2)(C(7)H(6)NO)(H(2)O)]·CH(3)OH, the Ir(III) ion adopts an octa-hedral geometry, and is coordinated by two 3,5-difluoro-2-(pyridin-2-yl)phenyl ligands, one mol-ecule of water and one benzamidate anion. The two 2-(4,6-difluoro-phen-yl)pyridyl ligands are arranged in a cis-C,C' and trans-N,N' fashion. Additionally, there is a bystanding methanol mol-ecule outside the coordination sphere of the Ir(III) ion. In the crystal, mol-ecules of the title compound are linked by O-H⋯O and O-H⋯N hydrogen bonds. One F atom of each ligand is equally disordered over two sites. The C atom of the solvent molecule is likewise disordered over two sites in a 0.589 (11):0.411 (11) ratio.
Acta Crystallographica Section E Structure Reports Online 03/2012; 68(Pt 3):m310. · 0.35 Impact Factor
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ABSTRACT: The most-popular strategy to improve the cycling stability and rate performance of the sulfur electrode in lithium-sulfur (Li-S) batteries is to astrict the sulfur in a conducting medium by using complicated chemical/physical processing. Lithium sulfide (Li(2)S) has been proposed as an alternative electrode material to sulfur. However, for its application, it must meet challenges such as high instability in air together with all of the drawbacks of a sulfur-containing electrode. Herein, we report the feasibility of using Li(2)S, which was obtained by electrochemical conversion of commercial molybdenum disulfide (MoS(2)) into Li(2)S and metallic molybdenium (Mo) at low voltages, as a high-performance active material in Li-S batteries. Metallic Mo prevented the dissolution of lithium polysulfides into the electrolyte and enhanced the conductivity of the sulfide electrode. Therefore, the in situ electrochemically prepared Li(2)S/Mo composite exhibited both high cycling stability and high sulfur utilization.
Chemistry - An Asian Journal 02/2012; 7(5):1013-7. · 4.50 Impact Factor
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ABSTRACT: It has been a very long history for human to resist diseases. During this period, a large number of drugs that could kill or inhibit the growth of microbe has been discovered, most of which were natural products. However, there may still be a large amount of antimicrobial medicines in natural compounds which have not been found yet. The ways of screening for antimicrobial always cost a long time and need a lot of manpower before. However, in recent years, a lot of new antimicrobial targets, antimicrobial drugs and screening methods which are simpler, faster and more efficient have been invented. In this paper the newly discovered targets, natural products and representative technologies were reviewed, which were expected to make some contributions to the research and development of medicines.
Combinatorial chemistry & high throughput screening 01/2012; 15(4):306-15. · 2.46 Impact Factor
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Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology 12/2011; 46(12):765.
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ABSTRACT: To evaluate the snail control effect of a film covering method in fish ponds and ditches.
Two fish ponds and 2 ditches with Oncomelania snails were selected as pilots, and 1 fish pond as Group A1 and I ditch as Group B1 received niclosamide spraying + film covering, and another fish pond as Group A2 and another ditch as Group B2 received niclosamide spraying only. The snail control effects were observed at 15, 30, 90 d and 360 d after the test, and the fish and other aquatic were also observed.
In Group A1, the adjusted mortality rates of snails were 92.31%, 99.36% and 100% at 15, 30 d and 90 d after the test, respectively; in Group B1, the adjusted mortality rates of snails were 91.45%, 95.84% and 100% at 15, 30 d and 90 d after the test, respectively; and there was no death of fish. The densities of snails were 0 and 0.07 snails/0.1 m2 one year after the test, respectively. In Group A2, the adjusted mortality rates of snails were 75.36%, 72.59% and 65.76% at 15 d, 30 d and 90 d after the test, respectively; in Group B2, the adjusted mortality rates of snails were 70.36%, 72.87% and 75.82% at 15, 30 d and 90 d after the test, respectively; and there was death of fish. The densities of snails were 0.11 snails/0.1 m2 and 0.13 snails/0.1 m2 one year after the test, respectively.
In ponds and ditches with snails, the niclosamide spraying + film covering method is very effective and safe.
Zhongguo xue xi chong bing fang zhi za zhi = Chinese journal of schistosomiasis control. 12/2011; 23(6):695-6, 707.
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Advanced Materials 11/2011; 23(43):5081-5. · 13.88 Impact Factor
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ABSTRACT: Novel sulfur/polythiophene composites with core/shell structure composites were synthesized via an in situ chemical oxidative polymerization method with chloroform as a solvent, thiophene as a reagent, and iron chloride as an oxidant at 0 °C. Different ratios of the sulfur/polythiophene composites were characterized by elemental analysis, FTIR, XRD, SEM, TEM, and electrochemical methods. A suitable ratio for the composites was found to be 71.9% sulfur and 18.1% polythiophene as determined by CV and EIS results. Conductive polythiophene acts as a conducting additive and a porous adsorbing agent. It was uniformly coated onto the surface of the sulfur powder to form a core/shell structure, which effectively enhances the electrochemical performance and cycle life of the sulfur cells. The initial discharge capacity of the active material was 1119.3 mA h g−1, sulfur and the remaining capacity was 830.2 mA h g−1 sulfur after 80 cycles. After a rate test from 100 to 1600 mA g−1 sulfur, the cell remained at 811 mA h g−1 sulfur after 60 cycles when the current density returned to 100 mA g−1 sulfur. The sulfur utilization, the cycle life, and the rate performance of the S−PTh core/shell electrode in a lithium−sulfur battery improved significantly compared to that of the pure sulfur electrode. The pore and thickness of the shell affected the battery performance of the lithium ion diffusion channels.
03/2011;
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ABSTRACT: Energy storage was realized on the interfaces between Fe and Li3PO4 nanograins in situ fabricated by discharging commercial LiFePO4 to 0.005 V vs Li+/Li. X-ray diffraction and high-resolution transmission electron microscopy indicate that both the metallic Fe and Li3PO4 nanocrystallites are stable up to 4.2 V. The solid electrolyte interphase layer on the nanocomposite does not decompose until 1.7 V according to infrared spectroscopic analysis. The Fe/Li3PO4 nanocomposite stores up to 220 mAh g−1 of lithium without any electrochemical reactions. This is a purely lithium storage behavior distinct from that on the electrodes of supercapacitors or traditional secondary batteries.
02/2011;
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ABSTRACT: We investigated an environmentally friendly leaching process for the recovery of cobalt and lithium from the cathode active materials of spent lithium-ion batteries. The easily degradable organic acid DL-malic acid (C(4)H(5)O(6)) was used as a leaching reagent. The structural, morphology of the cathode materials before and after leaching were characterized by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The amount of Co and Li present in the leachate was determined by atomic absorption spectrophotometry (AAS). Conditions for achieving a recovery of more than 90 wt.% Co and nearly 100 wt.% Li were determined experimentally by varying the concentrations of leachant, time and temperature of the reaction as well as the initial solid-to-liquid ratio. We found that hydrogen peroxide in a DL-malic acid solution is an effective reducing agent because it enhances the leaching efficiency. Leaching with 1.5M DL-malic acid, 2.0 vol.% hydrogen peroxide and a S:L of 20 g L(-1) in a batch extractor results in a highly efficient recovery of the metals within 40 min at 90 °C.
Waste Management 12/2010; 30(12):2615-21. · 2.43 Impact Factor
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ABSTRACT: In this work, a hydrometallurgical process based on leaching is applied to recover cobalt and lithium from spent lithium ion batteries (LIBs). Citric acid and hydrogen peroxide are introduced as leaching reagents and the leaching of cobalt and lithium with a solution containing C(6)H(8)O(7) x H(2)O is investigated. When both C(6)H(8)O(7) x H(2)O and H(2)O(2) are used an effective recovery of Li and Co as their respective citrates is possible. The leachate is characterized by scanning electron micrography (SEM) and X-ray diffraction (XRD). The proposed procedure includes the mechanical separation of metal-containing particles and a chemical leaching process. Conditions for achieving a recovery of more than 90% Co and nearly 100% Li are achieved experimentally by varying the concentrations of leachant, time and temperature of the reaction as well as the starting solid-to-liquid ratio. Leaching with 1.25 M citric acid, 1.0 vol.% hydrogen peroxide and a S:L of 20 g L(-1) with agitation at 300 rpm in a batch extractor results in a highly efficient recovery of the metals within 30 min of the processing time at 90 degrees C. This hydrometallurgical process is found to be simple, environmentally friendly and adequate for the recovery of valuable metals from spent LIBs.
Journal of hazardous materials 11/2009; 176(1-3):288-93. · 4.14 Impact Factor
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ABSTRACT: The bioleaching mechanism of Co and Li from spent lithium-ion batteries by mixed culture of sulfur-oxidizing and iron-oxidizing bacteria was investigated. It was found that the highest release of Li occurred at the lowest pH of 1.54 with elemental sulfur as an energy source, the lowest occurred at the highest pH of 1.69 with FeS(2). In contrast, the highest release of Co occurred at higher pH and varied ORP with S + FeS(2), the lowest occurred at almost unchanged ORP with S. It is suggested that acid dissolution is the main mechanism for Li bioleaching independent of energy matters types, however, apart from acid dissolution, Fe(2+) catalyzed reduction takes part in the bioleaching process as well. Co(2+) was released by acid dissolution after insoluble Co(3+) was reduced into soluble Co(2+) by Fe(2+) in both FeS(2) and FeS(2) + S systems. The proposed bioleaching mechanism mentioned above was confirmed by the further results obtained from the experiments of bioprocess-stimulated chemical leaching and from the changes in structure and component of bioleaching residues characterized by XPS, SEM and EDX.
Bioresource technology 09/2009; 100(24):6163-9. · 4.25 Impact Factor
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ABSTRACT: Binary room-temperature complex electrolytes have been synthesized based on lithium bis(trifluoromethane sulfone) imide [
, LiTFSI] and organic molecules with amide (acylamino) groups such as ethyleneurea, acetamide, etc. The thermal properties
and electrochemical performances of the complex systems are evaluated with differential scanning calorimetry (DSC), ac impedance
spectroscopy, cyclic voltammetry (CV), and in a test electric double layer capacitor, respectively. DSC analysis shows that
the eutectic temperatures of most complex systems are below 0°C. The ionic conductivities of these complex systems exceed
at room temperature. Analysis of their CV behavior indicates that the electrochemical stability windows of these electrolytes
are over 4 V. These complex systems prove to be promising candidates of electrolytes for supercapacitor and other electrochemical
devices.
Journal of The Electrochemical Society. 09/2005; 152(10):A1979-A1984.
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ABSTRACT: A novel room-temperature molten salt electrolyte based on urea and lithium bis(trifluoromethane sulfone)imide (LiN(SO2CF3)2, LiTFSI) has been synthesized and characterized by differential scanning calorimetry (DSC), Raman spectroscopy, ac impedance, and cyclic voltammetry. This electrolyte appears as a liquid at room temperature, though it is composed of two solids. DSC shows that its eutectic temperature is about −37.60 °C. Strong interactions between the two components observed by Raman spectroscopy weaken the bonding between the anions and the cations of LiTFSI, leading to the formation of a eutectic molten salt. The conduction behavior and the electrochemical window of this electrolyte have been evaluated by ac impedance spectroscopy and cyclic voltammetry, respectively.
09/2001;
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ABSTRACT: Binary room temperature complex electrolytes based on lithium bis(trifluoromethane sulfone) imide (LiN(SO2CF3)2, LiTFSI) and organic molecules with acylamino (amide) groups, such as ethyleneurea, acetamide, etc., have been synthesized and evaluated with differential scanning calorimetry (DSC) and ac impedance spectroscopy. Most of the complex systems with proper molar ratio have excellent thermal stability and electrochemical performance. Infrared (IR) and Raman spectroscopic studies have been carried out to understand the formation these electrolytes. It is shown that the organic compounds with amide group can coordinate with the Li+ cation and the TFSI− anion via their polar groups (the CO and NH groups). Such strong interactions lead to the dissociation of LiTFSI and the breaking of the hydrogen bonds among the organic molecules, resulting in the formation of the complex systems. In order to have a comprehensive understanding of the above interactions and the structure–activity relationship of these complex systems, the Mulliken charges on the O and N atoms, the equilibrium configuration and the bonding energy of the systems have been determined by quantum chemistry calculations with non-local density function theory (DFT). The calculations indicate that the structure and the substitution group of organic molecules influence the charge density and coordination strength of the carbonyl oxygen of these molecules. In addition, the strength of hydrogen bonding between the organic molecules influences the physico-chemical properties of the complex electrolyte.
Vibrational Spectroscopy 44(2):297-307. · 1.65 Impact Factor
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ABSTRACT: Two novel iridium(III) complexes containing 2-(4,6-difluorophenyl)pyridyl cyclometalating ligand and amidate ancillary ligands were synthesized and characterized by NMR and X-ray crystallographic methods. Photophysical properties including UV–vis absorption and photoluminescence spectra were studied, indicating that the electronic properties of the amidate ancillary ligand exhibit a significant effect on the emitting excited states of these iridium(III) amidate complexes and thus lead to different emission colors.Graphical abstractTwo new photoluminescent iridium(III) 2-(4,6-difluorophenyl)pyridyl complexes containing N-phenylbenzamidate and N-phenylacetamidate ancillary ligands were synthesized and characterized. Photophysical property studies show that the electronic properties of amidate ancillary ligand exhibit a critical effect on the emission color of the Ir(III) amidate complexes.Research highlights► Ir(III) 2-(4,6-difluorophenyl)pyridyl complexes with amidate ancillary ligand. ► Tuning emission color by simply altering the structure of amidate ligand. ► Amidate ligands affect the energy level of emitting excited states. ► Amidate ligands affect inter-ligand energy transfer.
Inorganic Chemistry Communications 14(9):1414-1417. · 1.97 Impact Factor
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ABSTRACT: A two-dimensional thermal model was presented to predict the temperature distribution of cylindrical 8-Ah Ni/MH battery. Under the forced convection, the temperature rise of the battery is up to about 37, 42 and 51 °C, and the temperature profiles become non-uniformed at the end of 1C, 2C and 4C rate charge, respectively. It is indicated that the increase of the convection coefficient can decrease the battery temperature, however, lead seriously to the less uniform temperature profile across the battery. The numerical studies indicate that the increase of thermal conductivity can improve the uniformity of temperature profile to some extends. The battery temperature increases obviously when charged at higher rates. Overcharge can result in an increasingly higher temperature rise and a steeper temperature gradient within a battery.
Journal of Power Sources.
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ABSTRACT: We propose an online algorithm for planning under uncertainty in multi-agent settings modeled as DEC-POMDPs. The algorithm helps overcome the high computational complexity of solving such problems offline. The key challenges in decentralized operation are to maintain coordinated behavior with little or no communication and, when communication is allowed, to optimize value with minimal communication. The algorithm addresses these challenges by generating identical conditional plans based on common knowledge and communicating only when history inconsistency is detected, allowing communication to be postponed when necessary. To be suitable for online operation, the algorithm computes good local policies using a new and fast local search method implemented using linear programming. Moreover, it bounds the amount of memory used at each step and can be applied to problems with arbitrary horizons. The experimental results confirm that the algorithm can solve problems that are too large for the best existing offline planning algorithms and it outperforms the best online method, producing much higher value with much less communication in most cases. The algorithm also proves to be effective when the communication channel is imperfect (periodically unavailable). These results contribute to the scalability of decision-theoretic planning in multi-agent settings.
Artificial Intelligence.
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ABSTRACT: TiO2 electrodes are coated with NiO by DC magnetron sputtering, and their structural, optical and electrochemical performance has been investigated. X-ray diffractometry (XRD), UV–vis spectrophotometry, scanning electron microscopy (SEM), AC impedance, and linear sweep voltammetry (LSV) are used to characterize the TiO2/NiO electrodes. Their performance is evaluated with a computer controlled electrochemical workstation in combination with three conventional electrodes. The experimental results indicate that the surface modification of TiO2 electrodes with sputtered NiO reduces trap sites on TiO2 and improves the electrochemical performance of dye-sensitized solar cells (DSSCs). Sputtering NiO for 7 min, which is about 21 nm thick, on 6.5 μm thick TiO2 greatly improves the DSSC parameters, and the conversion efficiency increases from 3.21 to 4.16%. Mechanisms of the influence of the NiO coating on electrochemical performance are discussed.
Applied Surface Science.
