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We report new nanocomposites with poly(benzoxazine-co-epoxy) matrix reinforced with 1 wt% graphene. Curabox 24-111, a benzoxazine resin was copolymerised with Epilok 60-566, a mixture of epoxy resins. Copolymerisation was also carried out in the presence of different graphene powders, namely, Nanene-001 and Nanene-002, used as single fillers and as mixture (relative weight ratio 70:30 or 30:70). DSC results showed the addition of either single filler caused a delay in polymerisation and an increase in the exothermic peak temperature of the curing reaction with a related reduction in ΔH Total. compared to the neat copolymer. Copolymerisation showed a 38% reduction and 24% increase in tensile modulus (E) compared to the neat polybenzoxazine and epoxy polymer, with a respective 18% and 30% reduction in tensile strength (TS). Nanocomposites with 0.7wt% Nanene-002 + 0.3 wt% Nanene-001 showed the highest increase of 35% in TS, a 1.6% reduction in E and 36% increase in elongation at break (EB) compared to the neat copolymer matrix. Samples with 1 wt% Nanene-001 showed the largest reduction of 21% in E, a 27% increase in TS and a 45% increase in EB. Additionally, TGA thermographs showed a 22°C increase in the onset of degradation (300°C–322°C) improving the materials thermal stability.

Multiple studies have reported the observation of electro-synaptic response in different metal/insulator/metal devices; however, most of them analysed large (>1 µm2) devices that do not meet the integration density required by the industry (1010 devices/mm2). Some studies employed a scanning tunnelling microscope (STM) to explore nano-synaptic response in different materials, but in this setup there is a nanogap between the insulator and one of the metallic electrodes (i.e. the STM tip), which is not present in real devices. Here we show how to use a conductive atomic force microscope (CAFM) to explore the presence and quality of nano-synaptic response in confined areas

Graphene is a highly desirable material for a variety of applications; in the case of nanocomposites, it can be functionalized and added as a nanofiller to alter the ultimate product properties, such as tensile strength. However, often the material properties of the functionalized graphene and the location of any chemical species, attached via different functionalization processes, are not known. Thus, it is not necessarily understood why improvements in product performance are achieved, which hinders the rate of product development. Here, a commercially available powder containing few-layer graphene (FLG) flakes is characterized before and after plasma or chemical functionalization with either nitrogen or oxygen species. A range of measurement techniques, including tip-enhanced Raman spectroscopy (TERS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and NanoSIMS, were used to examine the physical and chemical changes in the FLG material at both the micro- and nanoscale. This is the first reported TERS imaging of commercially available FLG flakes of submicron lateral size, revealing the location of the defects (edge versus basal plane) and variations in the level of functionalization. Graphene-polymer composites were then produced, and the dispersion of the graphitic material in the matrix was visualized using ToF-SIMS. Finally, mechanical testing of the composites demonstrated that the final product performance could be enhanced but differed depending on the properties of the original graphitic material.

Energy filtering has been a long-sought strategy to enhance a thermoelectric material's figure of merit zT through improving its power factor. Here we show a composite of multi-layer graphene nanoplatelets (GNP) and n-type Mg3Sb2 leads to the expression of an energy filtering like effect demonstrated by an increase in the material's Seebeck coefficient and maximum power factor, without impact on the material's carrier concentration. We analyse these findings from the perspective of a heterogeneous material consisting of grain and grain boundary phases, instead of a more traditional and common analysis that assumes a homogeneously transporting medium. An important implication of this treatment is that it leads to the development of an interfacial Seebeck coefficient term, which can explain the observed increase in the material's Seebeck coefficient. The contribution of this interfacial Seebeck coefficient to the overall Seebeck coefficient is determined by the relative temperature drop across the grain boundary region compared to that of the bulk material. In Te doped Mg3Sb2 we show the introduction of GNP increases the interfacial thermal resistance of grain boundaries, enhancing the contribution of the interfacial Seebeck coefficient arising from grain boundaries to the overall Seebeck coefficient. Without significant detriment to the electrical conductivity this effect results in a net increase in maximum power factor. This increased interfacial thermal resistance also leads to the synergistic reduction of the total thermal conductivity. As a result, we enhance zT of the Mg3Sb2 to a peak value of 1.7 near 750 K. Considering the two-dimensional nature of the grain boundary interface, this grain boundary engineering strategy could be applied to a few thermoelectric systems utilizing various two-dimensional nanomaterials.

This Research Article discusses the growth of polycrystalline, self-supporting ZnO nanofibers, which can detect nitrogen dioxide (NO2) gas down to 1 part per billion (ppb), one of the smallest detection limits reported for NO2 using ZnO. A new and innovative method has been developed for growing polycrystalline ZnO nanofibers. These nanofibers have been created using core-shell electrospinning of inorganic metal precursor zinc neodecanoate, where growth occurs at the core of the nanofibers. This process produces contamination-free, self-supporting, polycrystalline ZnO nanofibers of an average diameter and grain size 50 and 8 nm, respectively, which are ideal for gas sensing applications. This process opens up an exciting opportunity for creating nanofibers from a variety of metal oxides, facilitating many new applications especially in the areas of sensors and wearable technologies.

A series of boronic acid-containing saccharide receptors was synthesised via copper catalysed azide–alkyne cycloaddition (CuAAC) reactions. Their saccharide binding capacity was studied by 1H and 11B NMR spectroscopy titrations and isothermal titration calorimetry (ITC) techniques. Fluorescent sensors were generated by linking a phenylboronic acid (PBA) receptor with fluorophores via a triazole-linker. Fluorescence titrations with fructose revealed that the substitution pattern about the PBA influences the fluorescence response to saccharides. Titrations studied by 1H NMR spectroscopy suggested that fructose binding is enhanced when the aromatic ring bearing the boronic acid has the triazole-containing substituent at the ortho position. No evidence of either a dative N–B bond or solvent insertion (between B and N) was observed by 11B NMR spectroscopy. These results demonstrate that synthetic accessible triazole receptors may allow rapid sensor synthesis, screening and discovery.

This Research Article discusses the growth of polycrystalline, self-supporting ZnO nanofibers, which can detect nitrogen dioxide (NO

Background: There is limited data on the effects of Childhood Maltreatment (CM) on pediatric mood disorders in general and pediatric Bipolar Disorder (BD) in particular. We aimed to compare clinical and family characteristics of youth with CM and Mood Disorder Not Otherwise Specified (MD) to youth with CM and BD and to follow the youth with MD longitudinally to determine their course of illness. Methods: Twenty-two youths (ages 8-18 years) with mood symptoms (11 with BD and 11 with MD) and histories of CM prior to the age of 5 years were assessed using a structured clinical interview. A follow-up assessment was conducted with 8 of the 11 parents of youth with MD. Results: 11 subjects (5 females, mean age 13 ± 2.4 sd) met DSMIV-TR criteria for BD and 11 subjects (4 females, mean age 12.5 ± 3.1 sd) met DSM-IV-TR criteria for MD. BD subjects had a higher number of lifetime major depressive episodes (BD=18.9 versus MD=4, z(20)=-2.5, p=0.01) and lifetime manic episodes (BD=17.7 MD=0.3, z(19)=-5.1,p

Sulfur dioxide (SO2) emission has become a crucial problem, especially in developing countries since it is one of the main reasons for the formation of acid precipitation and the secondary formation of fine particulate matter (PM2.5). Wet magnesia desulfurization stands out as a widely used practical approach for the control of SO2 due to its high removal efficiency, low operating cost and potential valuable by-products. However, the effluent of magnesium sulfite (main by-product) can reemit SO2 and cause water pollution. Thus, it is important, but challenging, to enhance the oxidation rate to improve the utilization of MgSO4 for sustainable resources and meanwhile downsize the absorbing tower. Herein, we report a series of graphitic carbon nitride (g-C3N4)-assembled transition metal catalysts (M–C3N4) for the first time via a facile and environmentally friendly synthetic route as a new generation of catalysts for the oxidation of magnesium sulfite. We have performed both theoretical evaluation and deep experimental validation of the series of M–C3N4 materials, and in particular, the cobalt–C3N4 material since it possesses the best catalytic activity reported to date, which is comparable to that of aqueous precious metal benchmarks but only with a 2.4 wt% cobalt loading. Additionally, the ability to recycle the Co–C3N4 complex is investigated to facilitate its practical application. This fabrication method is expected to provide a new concept for the construction of multifunctional nanocomposites for a large variety of industrially relevant desulfurization applications.

The development of piezoelectric layered materials may be one of the key elements enabling expansion of nanotechnology, as they offer a solution for the construction of efficient transducers for a wide range of applications, including self-powered devices. Here, we investigate the piezoelectric effect in multilayer (ML) stepped MoS2 flakes obtained by liquid-phase exfoliation, which is especially interesting because it may allow the scalable fabrication of electronic devices using large area deposition techniques (e.g. solution casting, spray coating, inkjet printing). By using a conductive atomic force microscope we map the piezoelectricity of the MoS2 flakes at the nanoscale. Our experiments demonstrate the presence of electrical current densities above 100 A cm−2 when the flakes are strained in the absence of bias, and the current increases proportional to the bias. Simultaneously collected topographic and current maps demonstrate that the edges of stepped ML MoS2 flakes promote the piezoelectric effect, where the largest currents are observed. Density functional theory calculations are consistent with the ring-like piezoelectric potential generated when the flakes are strained, as well as the enhanced piezoelectric effect at edges. Our results pave the way to the design of piezoelectric devices using layered materials.

Chemical and electrochemical reduction methods allow the dispersion, processing, and/or functionalization of discrete sp

We demonstrate a wavelength-tunable graphene-synchronized all-fiber laser with Yb and Er cavities spanning 1040–1080 and 1535–1560 nm, corresponding to ~2750–3200 cm−1 frequency detuning. We apply the laser to coherent anti-Stokes Raman spectroscopy.

A series of boronic acid-containing saccharide receptors was synthesised via copper catalysed azide–alkyne cycloaddition (CuAAC) reactions. Their saccharide binding capacity was studied by 1H and 11B NMR spectroscopy titrations and isothermal titration calorimetry (ITC) techniques. Fluorescent sensors were generated by linking a phenylboronic acid (PBA) receptor with fluorophores via a triazole-linker. Fluorescence titrations with fructose revealed that the substitution pattern about the PBA influences the fluorescence response to saccharides. Titrations studied by 1H NMR spectroscopy suggested that fructose binding is enhanced when the aromatic ring bearing the boronic acid has the triazole-containing substituent at the ortho position. No evidence of either a dative N–B bond or solvent insertion (between B and N) was observed by 11B NMR spectroscopy. These results demonstrate that synthetic accessible triazole receptors may allow rapid sensor synthesis, screening and discovery.

Gold nanoparticles (AuNPs) can be evenly deposited on single-walled carbon nanotubes (SWCNTs) via the reduction of the highly stable complex, chloro(triphenylphosphine) gold(I), with SWCNT anions ('nanotubides'). This methodology highlights the unusual chemistry of nanotubides and provides a blueprint for the generation of many other hybrid nanomaterials.

Strategies for forming liquid dispersions of nanomaterials typically focus on retarding reaggregation, for example via surface modification, as opposed to promoting the thermodynamically driven dissolution common for molecule-sized species. Here we demonstrate the true dissolution of a wide range of important 2D nanomaterials by forming layered material salts that spontaneously dissolve in polar solvents yielding ionic solutions. The benign dissolution advantageously maintains the morphology of the starting material, is stable against reaggregation and can achieve solutions containing exclusively individualized monolayers. Importantly, the charge on the anionic nanosheet solutes is reversible, enables targeted deposition over large areas via electroplating and can initiate novel self-assembly upon drying. Our findings thus reveal a unique solution-like behaviour for 2D materials that enables their scalable production and controlled manipulation.

Chemical charging of single-walled carbon nanotubes (SWCNTs) and graphenes to generate soluble salts shows great promise as a processing route for electronic applications, but raises fundamental questions. The reduction potentials of highly-charged nanocarbon polyelectrolyte ions were investigated by considering their chemical reactivity towards metal salts/complexes in forming metal nanoparticles. The redox activity, degree of functionalisation and charge utilisation were quantified via the relative metal nanoparticle content, established using thermogravimetric analysis (TGA), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and X-ray photoelectron spectroscopy (XPS). The fundamental relationship between the intrinsic nanocarbon electronic density of states and Coulombic effects during charging is highlighted as an important area for future research.

Richard McCreery opened the discussion of the paper by Robert Dryfe: You stated that Ru(hexamine) shows a depression of the outer sphere ET rate, on graphene, possibly due to the proximity of its redox potential to the Dirac point. If so, then other redox systems with different Es should show an increasing kinetic trend as the potential moves from the Dirac point. Has anyone observed such a trend?

Previously, reduced single-walled carbon nanotube anions have been used for effective processing and functionalization. Here we report individually separate and distinct (that is, discrete) single-walled carbon nanotube cations, directly generated from a pure anode using a non-aqueous electrochemical technique. Cyclic voltammetry provides evidence for the reversibility of this nanoion electrochemisty, and can be related to the complex electronic density of states of the single-walled carbon nanotubes. Fixed potentiostatic oxidation allows spontaneous dissolution of nanotube cations ('nanotubium'); Raman spectroscopy and transmission electron microscopy show that sequential fractions are purified, separating amorphous carbon and short, defective single-walled carbon nanotubes, initially. The preparation of nanotubium, in principle, enables a new family of nucleophilic grafting reactions for single-walled carbon nanotubes, exploited here, to assemble nanotubes on amine-modified Si surfaces. Other nanoparticle polyelectrolyte cations may be anticipated.

The dissolution of single-walled carbon nanotubes (SWCNTs) remains a fundamental challenge, reliant on aggressive chemistry or ultrasonication and lengthy ultracentrifugation. In contrast, simple nonaqueous electrochemical reduction leads to spontaneous dissolution of individualized SWCNTs from raw, unprocessed powders. The intrinsic electrochemical stability and conductivity of these nanomaterials allow their electrochemical dissolution from a pure SWCNT cathode to form solutions of individually separate and distinct (i.e., discrete) nanotube anions with varying charge density. The integrity of the SWCNT sp² framework during the charge/discharge process is demonstrated by optical spectroscopy data. Other than a reversible change in redox/solvation state, there is no obvious chemical functionalization of the structure, suggesting an analogy to conventional atomic electrochemical dissolution. The heterogeneity of as-synthesized SWCNT samples leads to the sequential dissolution of distinct fractions over time, with fine control over the electrochemical potential. Initial preferential dissolution of defective nanotubes and carbonaceous debris provides a simple, nondestructive means to purify raw materials without recourse to the usual, damaging, competitive oxidation reactions. Neutral SWCNTs can be recovered either by electroplating at an anode or by reaction with a suitable electrophile.

Single-walled carbon nanotubes (SWNTs) are a fundamental family of distinct molecules, each bearing the possibility of different reactivities due to their intrinsically distinct chemical properties. SWNT syntheses generate a heterogeneous mixture of species with varying electronic character, lengths, diameters and helicities, (n,m), as well as other amorphous, graphitic and metal catalyst impurities. In recent years, selective syntheses and post-synthetic separation strategies have advanced, driven by the requirement for pure SWNTs displaying particular features. Covalent surface modifications are widely-used to adapt SWNTs for specific applications with modified solubility, compatibility and specific functionalities. In many cases, such reactions have been found to be selective, illuminating the fundamentally distinct chemistry of each (n,m) species. This differential reactivity has found immediate utility in facilitating the sorting of nanotubes according to specific diameter, electronic properties and, most importantly, helicity. In this tutorial review, we discuss a wide range of selective reactions, the mechanisms that are thought to govern selectivity, and the challenges of separating, characterising and regenerating the modified SWNTs.

Single-walled carbon nanotubes (SWNTs) are a fundamental family of distinct molecules, each bearing the possibility of different reactivities due to their intrinsically distinct chemical properties. SWNT syntheses generate a heterogeneous mixture of species with varying electronic character, lengths, diameters and helicities, (n,m), as well as other amorphous, graphitic and metal catalyst impurities. In recent years, selective syntheses and post-synthetic separation strategies have advanced, driven by the requirement for pure SWNTs displaying particular features. Covalent surface modifications are widely-used to adapt SWNTs for specific applications with modified solubility, compatibility and specific functionalities. In many cases, such reactions have been found to be selective, illuminating the fundamentally distinct chemistry of each (n,m) species. This differential reactivity has found immediate utility in facilitating the sorting of nanotubes according to specific diameter, electronic properties and, most importantly, helicity. In this tutorial review, we discuss a wide range of selective reactions, the mechanisms that are thought to govern selectivity, and the challenges of separating, characterising and regenerating the modified SWNTs.

Nitrogen-14 and -15 NMR studies of imido (NR)-ligands have been made for 37 complexes of Ta, Mo, W, Re and Os, including bent NR ligands, with evidence of bent–linear fluxionality in solution, in concert with an OR or a second NR ligand. A striking difference from diazenido (NNR) or nitrosyl ligands is the small difference in nitrogen shift for linear and bent NR ligands, the latter appearing across the whole range for NR ligands of the metals studied (with R = H, Me, Et, But, CH2But, aryl or SiMe3) in complexes with co-ordination numbers ranging from four to seven, and OR, Cl, F, NHR, NR2, N(SiMe3)2, S2CNEt2, phosphine, diphosphine or oxo coligands. This range, δN–90 to 156, resembles that of linear ligating nitrogen in N2 and NO ligands; the shielding is higher than in nitrides, with low-energy n(N)→π* paramagnetic circulations, and lower than in bridging imides and amides. The deshielding on bending is much smaller than for NNR or NO ligands because the imido lowest-unoccupied molecular orbitals (LUMOs), mainly π*(MN) and σ*(MN), are higher-lying than the π*(NN) and π*(NO) LUMOs. Another difference in the imido ligand is the closer parallelism of the nitrogen and the metal shielding, both of which increase with (σ+π)-acceptor ability of the coligands (increasing the ligand-field splitting). In the [WCl4(NC6H4X-4)(thf)](thf = tetrahydrofuran) series, similarly, the nitrogen shielding increases in the sequence X = OMe < Me < H < F < Cl < NO2, with increase in (σ+π)-acceptor ability of the aromatic group. The overall pattern of imido-nitrogen shielding, including the periodicity of the metal dependence (the shielding increasing down the group of the metal, but decreasing across the row) thus resembles that of other π-donor ligands such as oxo and fluoro but differs from that of π-acceptor nitrogen ligands, such as N2, NNR or NO.

The clusters [Os3(CO)10(dppm)](dppm = Ph2PCH2PPh2) and [Os3(CO)10(dmpm)](dmpm = Me2PCH2PMe2) react with trimethylamine N-oxide in acetonitrile solution to give [Os3 CO)9-(dppm)(MeCN)](1) and [Os3(CO)9(dmpm)(MeCN)](2) respectively. The acetonitrile ligand of (1) and (2) is readily displaced by other two-electron donor ligands to give [Os3(CO)9(dppm)L][L = PPh3, P(OMe)3, or ButNC] and [Os3(CO)9(dmpm)L][L = P(OMe)3 or C2H4]. Thermolysis of [Os3(CO)9(dmpm)(C2H4)] or [Os3(CO)10(dmpm)] gives the cyclometallated product [Os3H (CO)9-(Me2PCHPMe2)]. The acetonitrile complex (1) also reacts with HX (X = Cl or SR, R = alkyl) to give clusters of general formula [Os3H(X)(CO)8(dppm)], whereas for X = OH or OMe the only product isolated is [Os3H(CO)8{Ph2PCH2PPh(C6H4)}]. The dmpm derivative (2) reacts similarly with HCl and RSH. The cluster [Os3H(OH)(CO)8(dppm)], which can be prepared from [Os2H-(OH)(CO)10] and dppm, was found to have a different structure from [Os3H(Cl)(CO)8(dppm)]. All the products were characterised by i.r. and n.m.r. spectroscopy. The structures of [Os3H(CO)9-(Me2PCHPMe2)] and [Os3H(OH)(CO)8(dppm)] were confirmed by X-ray crystallography.

Coherent Raman scattering (CRS) [1] is a nonlinear microscopy technique, which can enhance the Raman intensity by orders of magnitude compared to conventional spontaneous Raman measurements, ultimately reaching video-rate imaging speeds [1]. However, it comes at the cost of an increased experimental complexity. In particular, it requires synchronized ultra-fast lasers, where two ps pulses (pump and Stokes) are used to set up and detect a vibrational coherence within the sample [1,2]. This, together with the high cost and large footprint, still prevents CRS instrumentation from being translated to clinical environments.

The clusters [Os3(CO)10(dppm)](dppm = Ph2PCH2PPh2) and [Os3(CO)10(dmpm)](dmpm = Me2PCH2PMe2) react with trimethylamine N-oxide in acetonitrile solution to give [Os3 CO)9-(dppm)(MeCN)](1) and [Os3(CO)9(dmpm)(MeCN)](2) respectively. The acetonitrile ligand of (1) and (2) is readily displaced by other two-electron donor ligands to give [Os3(CO)9(dppm)L][L = PPh3, P(OMe)3, or ButNC] and [Os3(CO)9(dmpm)L][L = P(OMe)3 or C2H4]. Thermolysis of [Os3(CO)9(dmpm)(C2H4)] or [Os3(CO)10(dmpm)] gives the cyclometallated product [Os3H (CO)9-(Me2PCHPMe2)]. The acetonitrile complex (1) also reacts with HX (X = Cl or SR, R = alkyl) to give clusters of general formula [Os3H(X)(CO)8(dppm)], whereas for X = OH or OMe the only product isolated is [Os3H(CO)8{Ph2PCH2PPh(C6H4)}]. The dmpm derivative (2) reacts similarly with HCl and RSH. The cluster [Os3H(OH)(CO)8(dppm)], which can be prepared from [Os2H-(OH)(CO)10] and dppm, was found to have a different structure from [Os3H(Cl)(CO)8(dppm)]. All the products were characterised by i.r. and n.m.r. spectroscopy. The structures of [Os3H(CO)9-(Me2PCHPMe2)] and [Os3H(OH)(CO)8(dppm)] were confirmed by X-ray crystallography.