Crystal structures and hydrogen bonding in the anhydrous tryptaminium salts of the isomeric (2,4-dichlorophenoxy)acetic and (3,5-dichlorophenoxy)acetic acids

The anhydrous salts of 1H-indole-3-ethanamine (tryptamine) with isomeric (2,4-dichlorophenoxy)acetic acid (2,4-D) and (3,5-dichlorophenoxy)acetic (3,5-D), C10H13N2+ (C8H5Cl2O3)-, [(I) and (II), respectively] have been determined and their one-dimensional hydrogen-bonded polymeric structures are described. In the crystal of (I),the aminium H-atoms are involved in three separate inter-species N-H...O hydrogen-bonding interactions, two with carboxyl O-atom acceptors and the third in an asymmetric three-centre bidentate carboxyl O,O' chelate [graph set R2/1(4)]. The indole H-atom forms an N-H...O~carboxyl~ hydrogen bond, extending the chain structure along the b axial direction. In (II), two of the three aminium H-atoms are also involved in N-H...O(carboxyl) hydrogen bonds similar to (I) but with the third, a three-centre asymmetric interaction with carboxyl and phenoxy O-atoms is found [graph set R2/1(5)]. The chain polymeric extension is also along b. There are no pi--pi ring interactions in either of the structures. The aminium side chain conformations differ significantly between the two structures, reflecting the conformational ambivalence of the tryptaminium cation, as found also in the benzoate salts.

Anodized nanoporous WO3 Schottky contact structure for hydrogen and ethanol sensing

This paper reports the development of nanoporous tungsten trioxide (WO3) Schottky diode-based gas sensors. Nanoporous WO3 films were prepared by anodic oxidation of tungsten foil in ethylene glycol mixed with ammonium fluoride and a small amount of water. Anodization resulted in highly ordered WO3 films with a large surface-to-volume ratio. Utilizing these nanoporous structures, Schottky diode-based gas sensors were developed by depositing a platinum (Pt) catalytic contact and tested towards hydrogen gas and ethanol vapour. Analysis of the current–voltage characteristics and dynamic responses of the sensors indicated that these devices exhibited a larger voltage shift in the presence of hydrogen gas compared to ethanol vapour at an optimum operating temperature of 200 °C. The gas sensing mechanism was discussed, associating the response to the intercalating H+ species that are generated as a result of hydrogen and ethanol molecule breakdowns onto the Pt/WO3 contact and their spill over into nanoporous WO3.

Charge mediated semiconducting-to-metallic phase transition in molybdenum disulfide monolayer and hydrogen evolution reaction in new 1T′ phase

The phase transition of single layer molybdenum disulfide (MoS2) from semiconducting 2H to metallic 1T and then to 1T′ phases, and the effect of the phase transition on hydrogen evolution reaction (HER) are investigated within this work by density functional theory. Experimentally, 2H-MoS2 has been widely used as an excellent electrode for HER and can get charged easily. Here we find that the negative charge has a significant impact on the structural phase transition in a MoS2 monolayer. The thermodynamic stability of 1T-MoS2 increases with the negative charge state, comparing with the 2H-MoS2 structure before phase transition and the kinetic energy barrier for a phase transition from 2H to 1T decreases from 1.59 to 0.27 eV when 4e– are injected per MoS2 unit. Additionally, 1T phase is found to transform into the distorted structure (1T′ phase) spontaneously. On their activity toward hydrogen evolution reaction, 1T′-MoS2 structure shows comparable hydrogen evolution reaction activity to the 2H-MoS2 structure. If the charge transfer kinetics is taken into account, the catalytic activity of 1T′-MoS2 is superior to that of 2H-MoS2. Our finding provides a possible novel method for phase transition of MoS2 and enriches understanding of the catalytic properties of MoS2 for HER.

Multifunctional SA-PProDOT binder for lithium ion batteries

An environmentally benign, highly conductive, and mechanically strong binder system can overcome the dilemma of low conductivity and insufficient mechanical stability of the electrodes to achieve high performance lithium ion batteries (LIBs) at a low cost and in a sustainable way. In this work, the naturally occurring binder sodium alginate (SA) is functionalized with 3,4-propylenedioxythiophene-2,5-dicarboxylic acid (ProDOT) via a one-step esterification reaction in a cyclohexane/dodecyl benzenesulfonic acid (DBSA)/water microemulsion system, resulting in a multifunctional polymer binder, that is, SA-PProDOT. With the synergetic effects of the functional groups (e.g., carboxyl, hydroxyl, and ester groups), the resultant SA-PProDOT polymer not only maintains the outstanding binding capabilities of sodium alginate but also enhances the mechanical integrity and lithium ion diffusion coefficient in the LiFePO4 (LFP) electrode during the operation of the batteries. Because of the conjugated network of the PProDOT and the lithium doping under the battery environment, the SA-PProDOT becomes conductive and matches the conductivity needed for LiFePO4 LIBs. Without the need of conductive additives such as carbon black, the resultant batteries have achieved the theoretical specific capacity of LiFePO4 cathode (ca. 170 mAh/g) at C/10 and ca. 120 mAh/g at 1C for more than 400 cycles.

Effects of metal ion concentration on electrodeposited CuZnSn film and its application in kesterite Cu2ZnSnS4solar cells

In this study, effects of concentrations of Cu(II), Zn(II) and Sn(II) ions in the electrolytic bath solution on the properties of electrochemically deposited CuZnSn (CZT) films were investigated. Study of the composition of a CZT film has shown that the metallic content (relative atomic ratio) in the film increased linearly with increase in the metal ion concentration. It is the first time that the relationship of the compositions of the alloy phases in the co-electrodeposited CZT film with the concentration of metal ions has been revealed. The results have confirmed that the formation and content of Cu6Sn5 and Cu5Zn8 alloy phases in the film were directly controlled by the concentration of Cu(II). SEM measurements have shown that Sn(II) has significant impact on film morphology, which became more porous as a result of the larger nucleation size of tin. The changes in the surface properties of the films was also confirmed by chronoamperometry characteristic (i–t) deposition curves. By optimization of metal ion concentrations in the electrolyte solution, a copper-poor and zinc-rich kesterite Cu2ZnSnS4 (CZTS) film was synthesized by the sulfurization of the deposited CZT film. The solar cell with the CZTS film showed an energy conversion efficiency of 2.15% under the illumination intensity of 100 mW cm 2.

Patenting free energy: The BlackLight litigation and the hydrogen economy

Legal Context In the wake of the Copenhagen Accord 2009 and the Cancun Agreements 2010, a number of patent offices have introduced fast-track mechanisms to encourage patent applications in relation to clean technologies - such as those pertaining to hydrogen. However, patent offices will be under increasing pressure to ensure that the granted patents satisfy the requisite patent thresholds, as well as to identify and reject cases of fraud, hoaxes, scams, and swindles. Key Points This article examines the BlackLight litigation in the United States, the United Kingdom, and the European Patent Office, and considers how patent offices and courts deal with patent applications in respect of clean energy and perpetual motion machines. Practical Significance The capacity of patent offices to grant sound and reliable patents is critical to the credibility of the patent system, particularly in the context of the current focus upon promoting clean technologies.

Clinoenstatite coatings have high bonding strength, bioactive ion release, and osteoimmunomodulatory effects that enhance in vivo osseointegration

A number of coating materials have been developed over past two decades seeking to improve the osseointegration of orthopedic metal implants. Despite the many candidate materials trialed, their low rate of translation into clinical applications suggests there is room for improving the current strategies for their development. We therefore propose that the ideal coating material(s) should possess the following three properties: (i) high bonding strength, (ii) release of functional ions, and (iii) favourable osteoimmunomodulatory effects. To test this proposal, we developed clinoenstatite (CLT, MgSiO3), which as a coating material has high bonding strength, cytocompability and immunomodulatory effects that are favourable for in vivo osteogenesis. The bonding strength of CLT coatings was 50.1 ± 3.2 MPa, more than twice that of hydroxyapatite (HA) coatings, at 23.5 ± 3.5 MPa. CLT coatings released Mg and Si ions, and compared to HA coatings, induced an immunomodulation more conducive for osseointegration, demonstrated by downregurelation of pro-inflammatory cytokines, enhancement of osteogenesis, and inhibition of osteoclastogenesis. In vivo studies demonstrated that CLT coatings improved osseointegration with host bone, as shown by the enhanced biomechanical strength and increased de novo bone formation, when compared with HA coatings. These results support the notion that coating materials with the proposed properties can induce an in vivo environment better suited for osseointegration. These properties could, therefore, be fundamental when developing high-performance coating materials.

Pt/WO3 nanoplatelet/SiC Schottky diode based hydrogen gas sensor

This paper presents the fabrication and study of a Schottky diode based on Pt/WO3 nanoplatelet/SiC for H2 gas sensing applications. The nanostructured WO3 films were synthesized from tungsten (sputtered on SiC) via an acidetching method using a 1.5 M HNO3 solution. Scanning electron microscopy of the developed films revealed platelet crystals with thicknesses in the order of 20-60 nm and lengths between 100-700 nm. The current-voltage characteristic and dynamic response of the diodes were measured in the presence of air and 1% H2 gas balanced in air from 25 to 300°C. Upon exposure to 1% H2, voltage shifts of 0.64, 0.93 and 1.14 V were recorded at temperatures of 120, 200 and 300°C, respectively at a constant forward bias current of 500 μA.

The three-dimensional hydrogen-bonded structures in the ammonium and sodium salt hydrates of 4-aminophenylarsonic acid

The structures of two hydrated salts of 4-aminophenylarsonic acid (p-arsanilic acid), namely ammonium 4-aminophenylarsonate monohydrate, NH4(+)·C6H7AsNO3(-)·H2O, (I), and the one-dimensional coordination polymer catena-poly[[(4-aminophenylarsonato-κO)diaquasodium]-μ-aqua], [Na(C6H7AsNO3)(H2O)3]n, (II), have been determined. In the structure of the ammonium salt, (I), the ammonium cations, arsonate anions and water molecules interact through inter-species N-H...O and arsonate and water O-H...O hydrogen bonds, giving the common two-dimensional layers lying parallel to (010). These layers are extended into three dimensions through bridging hydrogen-bonding interactions involving the para-amine group acting both as a donor and an acceptor. In the structure of the sodium salt, (II), the Na(+) cation is coordinated by five O-atom donors, one from a single monodentate arsonate ligand, two from monodentate water molecules and two from bridging water molecules, giving a very distorted square-pyramidal coordination environment. The water bridges generate one-dimensional chains extending along c and extensive interchain O-H...O and N-H...O hydrogen-bonding interactions link these chains, giving an overall three-dimensional structure. The two structures reported here are the first reported examples of salts of p-arsanilic acid.

Directional synthesis of tin oxide@graphene nanocomposites via a one-step up-scalable wet-mechanochemical route for lithium ion batteries

Directional synthesis of SnO2@graphene nanocomposites via a one-step, low-cost, and up-scalable wetmechanochemical method is achieved using graphene oxide and SnCl2 as precursors. The graphene oxides are reduced to graphene while the SnCl2 is oxidized to SnO2 nanoparticles that are in situ anchored onto the graphene sheets evenly and densely, resulting in uniform SnO2@graphene nanocomposites. The prepared nanocomposites possess excellent electrochemical performance and outstanding cycling in Li-ion batteries.

Mobile gene silencing in Arabidopsis is regulated by hydrogen peroxide

In plants and nematodes, RNAi can spread from cells from which it is initiated to other cells in the organism. The underlying mechanism controlling the mobility of RNAi signals is not known, especially in the case of plants. A genetic screen designed to recover plants impaired in the movement but not the production or effectiveness of the RNAi signal identified RCI3, which encodes a hydrogen peroxide (H2O2)-producing type III peroxidase, as a key regulator of silencing mobility in Arabidopsis thaliana. Silencing initiated in the roots of rci3 plants failed to spread into leaf tissue or floral tissue. Application of exogenous H2O2 reinstated the spread in rci3 plants and accelerated it in wild-type plants. The addition of catalase or MnO2, which breaks down H2O2, slowed the spread of silencing in wild-type plants. We propose that endogenous H2O2, under the control of peroxidases, regulates the spread of gene silencing by altering plasmodesmata permeability through remodelling of local cell wall structure, and may play a role in regulating systemic viral defence.

Ortho-Dihydroxyl-9,10-anthraquinone dyes as visible-light sensitizers that exhibit a high turnover number for hydrogen evolution

Pt/TiO2 sensitized by the cheap and organic ortho-dihydroxyl-9,10-anthraquinone dyes, such as Alizarin and Alizarin Red, achieved a TON of approximately 10 000 (TOF > 250 h−1 for the first ten hours) during >80 hours of visible light irradiation (>420 nm) for photocatalytic hydrogen evolution when triethanolamine was used as the sacrificial donor. The stability and activity enhancements can be attributed to the two highly serviceable redox reactions involving the 9,10-dicarbonyl and ortho-dihydroxyl groups of the anthracene ring, respectively

Pre-lithiation of onion-like carbon/MoS2 nano-urchin anodes for high-performance rechargeable lithium ion batteries

Hybrid urchin-like nanostructures composed of a spherical onion-like carbon (OLC) core and MoS2 nanoleaves were synthesized by a simple solvothermal method followed by thermal annealing treatment. Compared to commercial MoS2 powder, MoS2/OLC nanocomposites exhibit enhanced electrochemical performance as anode materials of lithium-ion batteries (LIBs) with a specific capacity of 853 mA h g−1 at a current density of 50 mA g−1 after 60 cycles, and a moderate initial coulombic efficiency of 71.1%. Furthermore, a simple pre-lithiation method based on direct contact of lithium foil with MoS2/OLC nano-urchins was used to achieve a very high coulombic efficiency of 97.6% in the first discharge/charge cycle, which is at least 26% higher compared to that of pristine MoS2/OLC nano-urchins. This pre-lithiation method can be generalized to develop other carbon-metal sulfide nanohybrids for LIB anode materials. These results may open up a new avenue for the development of the next-generation high-performance LIBs.

Unimolecular reaction chemistry of a charge-tagged beta-hydroxyperoxyl radical

β-Hydroxyperoxyl radicals are formed during atmospheric oxidation of unsaturated volatile organic compounds such as isoprene. They are intermediates in the combustion of alcohols. In these environments the unimolecular isomerization and decomposition of β-hydroxyperoxyl radicals may be of importance, either through chemical or thermal activation. We have used ion-trap mass spectrometry to generate the distonic charge-tagged β-hydroxyalkyl radical anion, ˙CH2C(OH)(CH3)CH2C(O)O−, and investigated its subsequent reaction with O2 in the gas phase under conditions that are devoid of complicating radical–radical reactions. Quantum chemical calculations and master equation/RRKM theory modeling are used to rationalize the results and discern a reaction mechanism. Reaction is found to proceed via initial hydrogen abstraction from the γ-methylene group and from the β-hydroxyl group, with both reaction channels eventually forming isobaric product ions due to loss of either ˙OH + HCHO or ˙OH + CO2. Isotope labeling studies confirm that a 1,5-hydrogen shift from the β-hydroxyl functionality results in a hydroperoxyalkoxyl radical intermediate that can undergo further unimolecular dissociations. Furthermore, this study confirms that the facile decomposition of β-hydroxyperoxyl radicals can yield ˙OH in the gas phase.

Hydrogen-bonded supramolecular polymers as self-healing hydrogels: Effect of a bulky adamantyl substituent in the ureido-pyrimidinone monomer

In an attempt to generate supramolecular assemblies able to function as self-healing hydrogels, a novel ureido-pyrimidinone (UPy) monomer, 2-(N ′-methacryloyloxyethylureido)-6-(1-adamantyl)-4[1H]-pyrimidinone, was synthesized and then copolymerized with N,N-dimethylacrylamide at four different feed compositions, using a solution of lithium chloride in N,N-dimethylacetamide as the polymerization medium. The assembling process in the resulting copolymers is based on crosslinking through the reversible quadruple hydrogen bonding between side-chain UPy modules. The adamantyl substituent was introduced in order to create a “hydrophobic pocket” that may protect the hydrogen bonds against the disruptive effect of water molecules. Upon hydration to equilibrium, all copolymers generated typical hydrogels when their concentration in the hydrated system was at least 15%. The small-deformation rheometry showed that all hydrated copolymers were hydrogels that maintained a solid-like behavior, and that their extrusion through a syringe needle did not affect significantly this behavior, suggesting a self-healing capacity in these materials. An application as injectable substitutes for the eye's vitreous humor was proposed