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PurposeScience, technology, engineering, mathematics and medicine (STEMM) workplaces worldwide remain stubbornly resistant to gender equality initiatives. Leaders are vital to driving change, but the extent to which their capabilities lead to change remains unknown. This article examines STEMM leaders' gender competence to achieving transformative changes in gender inequality.Design/methodology/approachThis article examines the capability of STEMM leaders to act as change agents through an in-depth, qualitative analysis of perceptions of gender inequality, sexual harassment, sex discrimination and gender bias within their organisations. Findings are analysed using a customised tripartite gender competence schema, comprising commitment, knowledge and method (or know-how).FindingsThe findings suggest that while STEMM leaders may express a commitment to addressing gender inequality, misapprehensions about the nature and scope of the problem are likely to hamper efforts. Two key misapprehensions standout: a tendency to frame gender inequality in primarily numerical terms; and recourse to blaming external factors beyond STEMM for gender inequality in STEMM.Originality/valueThis article makes an original contribution by examining the gender competence of leaders in STEMM organisations, which has not been previously researched. The findings extend understanding of the salience of leaders' capabilities to lead change by identifying key gaps and misapprehensions in STEMM leaders' understanding of the nature and scope of the problem.

The use of various aspects of food processing, including the direct inclusion of nano-additives, are rapidly increasing in the field of nanotechnology to enhance the desired qualities in food production, use and storage. The important role of the human gut microbiota is well understood, including its influence on many physiological functions and its alterations, which play an essential role in various human diseases. Research exploring the effect of engineered and naturally occurring nanoparticles (NPs) in the gastrointestinal tract (GIT) of humans on commensal and pathogenic microorganisms is lacking and scarce. Studies should focus on the complex human gut microbiome when investigating the influence of NPs within a human body. Various materials, such as titanium dioxide, silver, silicon dioxide, iron dioxide and zinc oxide, show great potential in affecting the microbiota and causing clinical disorders including colitis, obesity, and immunological dysfunction. This review reports the influence of such nano- food additives towards the gut microbiota (GM), as well as methods to track and monitor the NPs in vivo using techniques such as electron microscopy after interaction with NPs and in vitro gut models currently used to examine the influence of NPs with GM, as well as their limitations.

Environmental monitoring is necessary to ensure the overall health and conservation of an ecosystem. However, ecosystems (e.g. air, water, soil), are complex, involving numerous processes (both native and external), inputs, contaminants, and living organisms. As such, monitoring an environmental system is not a trivial task. The data obtained from natural systems is often multifaceted and convoluted, as a multitude of inputs can be intertwined within the matrix of the information obtained as part of a study. This means that trends and important results can be easily overlooked by conventional and single dimensional data analysis protocols. Recently, chemometric methods have emerged as a powerful method for maximizing the details contained within a chemical data set. Specifically, chemometrics refers to the use of mathematical and statistical analysis methods to evaluate chemical data, beyond univariant analysis. This type of analysis can provide a quantitative description of environmental measurements, while also having the capacity to reveal previously overlooked trends in data sets. Applying chemometrics to environmental data allows us to identify and describe the inter-relationship of environmental drivers, sources of contamination, and their potential impact upon the environment. This review aims to provide a detailed understanding of chemometric techniques, how they are currently used in environmental monitoring, and how these techniques can be used to improve current practices. An enhanced ability to monitor environmental conditions and to predict trends would be greatly beneficial to government and research agencies in their ability to develop environmental policies and analytical procedures.

Flexible crystals are an emerging class of material with unique properties and a range of potential applications. Their relatively recent development means that mechanical characterisation protocols have not yet been widely established. There is a lack of quantitative flexibility measurements, such as the elastic modulus (Young's modulus), reported in the literature. In this work, we investigate amplitude modulated-frequency modulated atomic force microscopy (AM-FM AFM) as a fast, versatile method for measuring the elastic modulus of single flexible crystals. Specifically, the elastic modulus of single crystals of copper(ii) acetylacetonate (Cu(acac)2) was measured. The elastic modulus for Cu(acac)2 was found to be 4.79 ± 0.16 GPa. Importantly, this technique was able to map the variation in mechanical properties over the surface of the material with nanoscale resolution, showing some degree of correlation between surface morphology and elastic modulus. Additionally, the distribution of elastic modulus values can be measured at different locations on the crystal, giving a statistically robust distribution, which cannot be achieved using other methods.

Gastrointestinal (GIT) diseases have risen globally in recent years, and early detection of the host’s gut microbiota, typically through fecal material, has become a crucial component for rapid diagnosis of such diseases. Human fecal material is a complex substance composed of undigested macromolecules and particles, and the processing of such matter is a challenge due to the unstable nature of its products and the complexity of the matrix. The identification of these products can be used as an indication for present and future diseases; however, many researchers focus on one variable or marker looking for specific biomarkers of disease. Therefore, the combination of genomics, transcriptomics, proteomics and metabonomics can give a detailed and complete insight into the gut environment. The proper sample collection, sample preparation and accurate analytical methods play a crucial role in generating precise microbial data and hypotheses in gut microbiome research, as well as multivariate data analysis in determining the gut microbiome functionality in regard to diseases. This review summarizes fecal sample protocols involved in profiling coeliac disease.

For many years, an extensive array of chemometric methods have provided a platform upon which a quantitative description of environmental conditions can be obtained. Applying chemometric methods to environmental data allows us to identify and describe the interrelations between certain environmental drivers. They also provide an insight into the interrelationships between these drivers and afford us a greater understanding of the potential impact that these drivers can place upon the environment. However, an effective marriage of these two systems has not been performed. Therefore, it is the aim of this review to highlight the advantages of using chemometrics and sensors to identify hidden trends in environmental parameters, which allow the state of the environment to be effectively monitored. Despite the combination of chemometrics and sensors, to capture new developments and applications in the field of environmental sciences, these methods have not been extensively used. Importantly, although different parameters and monitoring procedures are required for different environments (e.g., air, water, soil), they are not distinct, separate entities. Contemporary developments in the use of chemometrics afford us the ability to predict changes in different aspects of the environment using instrumental methods. This review also provides an insight into the prevailing trends and the future of environmental sensing, highlighting that chemometrics can be used to enhance our ability to monitor the environment. This enhanced ability to monitor environmental conditions and to predict trends would be beneficial to government and research agencies in their ability to develop environmental policies and analysis procedures.

Polymer contamination is a major pollutant in all waterways and a significant concern of the 21st Century, gaining extensive research, media, and public attention. The polymer pollution problem is so vast; plastics are now observed in some of the Earth's most remote regions such as the Mariana trench. These polymers enter the waterways, migrate, breakdown; albeit slowly, and then interact with the environment and the surrounding biodiversity. It is these biodiversity and ecosystem interactions that are causing the most nervousness, where health researchers have demonstrated that plastics have entered the human food chain, also showing that plastics are damaging organisms, animals, and plants. Many researchers have focused on reviewing the macro and micro-forms of these polymer contaminants, demonstrating a lack of scientific data and also a lack of investigation regarding nano-sized polymers. It is these nano-polymers that have the greatest potential to cause the most harm to our oceans, waterways, and wildlife. This review has been especially ruthless in discussing nano-sized polymers, their ability to interact with organisms, and the potential for these nano-polymers to cause environmental damage in the marine environment. This review details the breakdown of macro-, micro-, and nano-polymer contamination, examining the sources, the interactions, and the fates of all of these polymer sizes in the environment. The main focus of this review is to perform a comprehensive examination of the literature of the interaction of nanoplastics with organisms, soils, and waters; followed by the discussion of toxicological issues. A significant focus of the review is also on current analytical characterisation techniques for nanoplastics, which will enable researchers to develop protocols for nanopolymer analysis and enhance understanding of nanoplastics in the marine environment.

Highly controlled deposition of exfoliated transition metal dichalcogenide (TMD) suspensions onto substrates is an important step for the creation of efficient and scalable energy, electronic, optical and sensing units. Traditional methods such as drop casting and spin coating generally result in non-uniform deposition. Some methods also require the incorporation of surfactants or initiator molecules, which contaminate the particles and require extra processing steps. Here we present a facile method for controlled and patterned deposition of films made of exfoliated TMDs over large areas. A liquid–liquid interface is achieved directly from the nanoflake suspension in dimethyl formamide, without addition of any surfactants or chemical modifiers. We demonstrate the reliable and large scale patterning of macroscopic uniform films from exfoliated TMDs, through the use of hydrophobically patterned substrates. Microcharacterisations show that the TMD nanoflakes assemble through edge-to-edge arrangement into densely-packed thin films. Additionally, heterofilms were also successfully demonstrated using the same liquid–liquid interface method, through simply mixing exfoliated MoS2 and WS2 suspensions together before film assembly. This fast approach to TMD thin film assembly provides a future platform for reliable controlled deposition and co-patterning of 2D materials on a large scale compatible with industrial standards.

There is ongoing interest in exploring new two-dimensional materials and exploiting their functionalities. Here, a top-down approach is used for developing a new morphology of ultrathin nanosheets from highly ordered bismuth sulfide crystals. The efficient chemical delamination method exfoliates the bulk powder into a suspension of corrugated ultrathin sheets, despite the fact that the Bi2S3 fundamental layers are made of atomically thin ribbons that are held together by van der Waals forces in two dimensions. Morphological analyses show that the produced corrugated sheets are as thin as 2.5 nm and can be as large as 20 μm across. Determined atomic ratios indicate that the exfoliation process introduces sulfur vacancies into the sheets, with a resulting stoichiometry of Bi2S2.6. It is hypothesized that the nanoribbons were cross-linked during the reduction process leading to corrugated sheet formation. The material is used for preparing field effect devices and was found to be highly p-doped, which is att...

This communication describes an infinite 1D ribbon metal–organic framework (MOF) that crystallizes to produce large channels (13.4 × 17.5 A) and exhibits strong aggregation enhanced fluorescence emission. The network is composed of tetrapyridine tetraphenylethene molecules coordinating to ZnCl2 nodes. When activated, the network exhibits enhanced turn-on fluorescence in response to methyl-substituted volatile organic compounds (VOCs) and quenching in response to nitro-substituted VOCs. This MOF shows potential as a valuable sensor due to its high surface area, highly fluorescent TPE moiety, and significant response to VOCs.

This paper reports a highly selective nitrite ion receptor based on an AIE-active tetraphenylethene-bearing amino functionality. In water, the receptor has been shown to be selective for nitrite ion (NO2−) over other anions (NO2−, CH3COO−, NO3−, CO32−, S2O32−, SO42−, HSO3−, and Cl−), with pronounced changes in absorption characteristics i.e. red-shift of ∼30 nm. The visual observation of colour change, shift in absorption, and enhancement of emission, clearly show that this receptor is very selective and sensitive to nitrite ions.

Planar 2D materials are possibly the ideal channel candidates for future field effect transistors (FETs), due to their unique electronic properties. However, the performance of FETs based on 2D materials is yet to exceed those of conventional silicon based devices. Here, a 2D channel thin film made from liquid phase exfoliated molybdenum oxide nanoflake inks with highly controllable substoichiometric levels is presented. The ability to induce oxygen vacancies by solar light irradiation in an aqueous environment allows the tuning of electronic properties in 2D substoichiometric molybdenum oxides (MoO3−x). The highest mobility is found to be ≈600 cm2 V−1 s−1 with an estimated free electron concentration of ≈1.6 × 1021 cm−3 and an optimal IOn/IOff ratio of >105 for the FETs made of 2D flakes irradiated for 30 min (x = 0.042). These values are significant and represent a real opportunity to realize the next generation of tunable electronic devices using electronic inks.

Novel ultrafine lamellar (α + β) microstructures comprising ultrafine (∼200–300 nm) α-laths and retained β phases were created via promoting in situ decomposition of a near α′ martensitic structure in Ti–6Al–4V additively manufactured by selective laser melting (SLM). As a consequence, the total tensile elongation to failure reached 11.4% while maintaining high yield strength above 1100 MPa, superior to both conventional SLM-fabricated Ti–6Al–4V containing non-equilibrium acicular α′ martensite and conventional mill-annealed Ti–6Al–4V. The formation and decomposition of α′ martensite in additively manufactured Ti–6Al–4V was studied via specially designed experiments including single-track deposition, multi-layer deposition and post-SLM heat treatment. The essential SLM additive manufacturing conditions for Ti–6Al–4V including layer thickness, focal offset distance and energy density, under which a near α′ martensitic structure forms in each layer and then in situ transforms into ultrafine lamellar (α + β) structures, were determined. This is the first fundamental effort that has realized complete in situ martensite decomposition in SLM-fabricated Ti–6Al–4V for outstanding mechanical properties.

This work focuses on three 2-D MOFs based on the ligand tetrapyridyltetraphenylethylene (tppe) with the metal ions manganese(II), nickel(II) and copper(II). These networks are all highly microporous with rhomboid channels measuring ∼14 × 17 A giving approximately 49% solvent accessible void space. These voids are filled with ordered tetrachloroethylene (TCE) molecules that act as structure directing agents, and the structures remain porous even after removal of TEC molecules. The networks were characterised via single crystal X-ray diffraction, powder XRD, TGA, FTIR, fluorescence spectroscopy, and elemental analysis. Gas absorption measurements on the desolvated networks indicate that the networks are moderately selective, and their behaviour was typical of similar MOF networks. The Ni2+ based tppe-MOF exhibited greater capacity to absorb polar gases despite structural similarities to the other networks.

Grinding-assisted sonication exfoliation of stratified materials such as MoS2 is a widely used method for the preparation of their single- and few-layer thick flakes. This work introduces a two-solvent step approach utilizing a separate solvent during the grinding phase, while implementing ethanol during exfoliation. It is found that the grinding solvent played a critical role, determining exfoliation yield, flake dimensions, and morphology, highlighting the importance of such parameters in the process. Furthermore, it is found that the commonly used N-methyl-2-pyrrolidone (NMP) leads to persistent residues on the exfoliated flakes, which may alter the properties of the flakes and interfere with the development of electronic devices and other applications. A solvent residue free exfoliation method is presented herein, which may be advantageous for future studies.

The removal of H2S gas molecules from an environment with other gas species is an important technological challenge for a number of applications. In this work, we developed a nanocomposite catalytic membrane made of polydimethylsiloxane (PDMS) with different weight concentrations of silver (Ag) nanoparticles to reactively remove H2S from CH4 and CO2 gas streams. PDMS was chosen as a model base polymer as Ag nanoparticles could be well dispersed into its matrix. At a small Ag nanoparticles loading of 1%, the catalytic membranes were able to remove more than 60% of H2S gas molecules. The characterization revealed that the exposure to H2S gas molecules transformed the Ag nanoparticles into a catalytic nanocompound made of Ag and Ag2S. The nanocompound then catalytically decomposed H2S, while it had much smaller effect on CO2 and almost no effect on CH4 gas species. The presented nanocomposite system demonstrates the ability to efficiently remove H2S from mixed gas streams and offers a plethora of environmental, agricultural, biotechnology and energy conversion applications.

Two novel solution-processable small organic molecules, 4,9-bis(4-(diphenylamino)phenyl)-2,7-dioctylbenzo[3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone (S6) and 4,9-bis(benzo[b]thiophen-2-yl)-2,7-dioctylbenzo[3,8]phenanthroline-1,3,6,8 (2H,7H)-tetraone (S7), have been successfully designed, synthesized, characterized, and applied in solution-processable photovoltaic devices. S6 and S7 contain a common electron-accepting moiety, naphthalene diimide (NDI), with different electron-donating moieties, triphenylamine (S6) and benzothiophene (S7), and are based on a donor–acceptor–donor structure. S7 was isolated as black, rod-shaped crystals. Its triclinic structure was determined by single crystal x-ray diffraction (XRD): space group $$P\bar{1}$$ , Z = 2, a = 9.434(5) A, b = 14.460(7) A, c = 15.359(8) A, α = 67.256(9) degrees, β = 80.356(11) degrees, γ = 76.618(10) degrees, at 150 Kelvin (K), R = 0.073. Ultraviolet–visible absorption spectra revealed that use of triphenylamine donor functionality with the NDI acceptor unit resulted in an enhanced intramolecular charge transfer (ICT) transition and reduction of the optical band gap compared with the benzothiophene analogue. Solution-processable inverted bulk heterojunction devices with the structure indium tin oxide/zinc oxide (30 nm)/active layer/molybdenum trioxide (10 nm)/silver (100 nm) were fabricated with S6 and S7 as donors and (6,6)-phenyl C70-butyric acid methyl ester (PC70BM) as acceptor. Power conversion efficiencies of 0.22% for S6/PC70BM and 0.10% for S7/PC70BM were achieved for the preliminary photovoltaic devices under simulated AM 1.5 illumination (100 mW cm−2). This paper reports donor–acceptor–donor modular small organic molecules, with NDI as central accepting unit, that have been screened for use in solution-processable inverted photovoltaic devices.

A new platform described as the liquid metal/metal oxide (LM/MO) framework is introduced. The constituent spherical structures of these frameworks are made of micro- to nanosized liquid metal spheres and nanosized metal oxides, combining the advantages of both materials. It is shown that the diameters of the spheres and the stoichiometry of the structures can be actively controlled. Additionally, the liquid suspension of these spheres demonstrates tuneable plasmon resonances. These spherical structures are assembled to form LM/MO frameworks which are capable of demonstrating high sensitivity towards low concentrations of heavy metal ions, and enhanced solar light driven photocalalytic activities. These demonstrations imply that the LM/MO frameworks are a suitable candidate for the development of future high performance electronic and optical devices.

A liquid-based organic solvent-assisted grinding and sonication method was adopted for the formation of two dimensional (2D) moderately hydrated α -MoO 3 nanoflake suspensions, with a flake thickness in the order of ∼1.4 nm. This thickness is equal to the largest unit cell parameter of α -MoO 3 . The implemented method had the advantage of simplicity and resulted in a high yield of nanoflakes that were highly crystalline across the planes. This method can be incorporated into 2D semiconducting material-enabled devices. Conductometric transduction templates based on drop-casted thin films of these 2D α -MoO 3 flakes were developed for H 2 gas sensing. The sensors showed large responses to H 2 gas with response and recovery time in the order of seconds. The impressive operation of these devices was attributed to the 2D flake-like structure of the thin films.

It is important for gas permeable membranes, employed in many industrial applications, to have a high permeability as the cost of many processes such as gas separation and sensing directly depend on it. Polydimethylsiloxane (PDMS) has been a widely utilized polymer within permeable membranes as it possesses high intrinsic flux. However, little attention has been placed on the effect of crosslinking temperatures during synthesis. In this work, PDMS membranes were prepared using a range of crosslinking temperatures and evaluated for their gas permeation towards CO 2 , N 2 and CH 4. The investigation of the effect of the crosslinking temperature on gas permeation of PDMS membranes revealed an optimum temperature of 75 °C at which the permeability increased (for N 2 from 360 to 590 Barrer, for CO 2 from 3190 to 3970 Barrer, and for CH 4 from 850 to 1000 Barrer). The vibrational and electron beam spectroscopy studies show that at this optimum temperature the structure of polymer chains is relaxed due to the reduction of the crosslinking density and an enhancement in the fractional free volume (FFV) within the polymer matrix, allowing more efficient diffusion of the gas molecules. Eventually, we demonstrate the extraordinary capability of the membranes crosslinked at 75 °C by incorporating them in sensing systems. Remarkably the sensors’ response with and without the presence of the improved membrane are nearly the same for CO 2 and only show a 30% decrease for CH 4 . This experiment depicts the strong potential of the developed membrane for efficient, passive and low cost gas phase separation of selected gas species.

Two-dimensional (2D) transition metal dichalcogenide semiconductors offer unique electronic and optical properties, which are significantly different from their bulk counterparts. It is known that the electronic structure of 2D MoS2, which is the most popular member of the family, depends on the number of layers. Its electronic structure alters dramatically at near atomically thin morphologies, producing strong photoluminescence (PL). Developing processes for controlling the 2D MoS2 PL is essential to efficiently harness many of its optical capabilities. So far, it has been shown that this PL can be electrically or mechanically gated. Here, we introduce an electrochemical approach to actively control the PL of liquid-phase-exfoliated 2D MoS2 nanoflakes by manipulating the amount of intercalated ions including Li(+), Na(+), and K(+) into and out of the 2D crystal structure. These ions are selected as they are crucial components in many bioprocesses. We show that this controlled intercalation allows for large PL modulations. The introduced electrochemically controlled PL will find significant applications in future chemical and bio-optical sensors as well as optical modulators/switches.

One-dimensional (1D), single-phase (0 0 2) crystalline zinc oxide (ZnO) nanorod (NR) based conductometric sensors have been developed and investigated toward ethanol (C 2 H 5 OH) vapor. The ZnO NRs were chemically deposited onto conductometric transducer of alumina substrates employing a simple hydrothermal method. To facilitate the nucleation of ZnO NRs for oriented growth from the substrate, a seed layer of ZnO nanoparticles was pre-deposited employing filtered cathodic vacuum arc (FCVA) deposition technique onto the substrate containing pre-patterned interdigital electrodes (IDTs). Micro-characterization studies revealed that the NRs have a single crystal 1D structure with an average diameter of 30–50 nm. The developed sensors were exposed toward ethanol of different concentrations at temperature up to 330 °C. An optimum sensor operational temperature was found between 280 and 310 °C. At this temperature range, high sensitivity, fast response and fast recovery in conjunction with a stable baseline occur. The long-term stability test of the developed sensors confirmed that they are highly stable with only less than 3% variation of the dynamic performances (baseline resistance, sensitivity, response and recovery time).

A simple technique to fabricate nanostructured WO3 thin films onto conductomeric transducers has been employed for ethanol sensing application. Initially, pure tungsten (W) thin films were deposited onto the substrate employing RF sputterer and followed by an etching process. Three types of etching agent were used: nitric (HNO3), sulphuric (H2SO4), and phosphoric (H3PO4) acid. It was found that the surface morphology and crystallinity of the WO3 films were heavily dependant to the etchants employed during the fabrication process. The developed sensors were tested towards ethanol vapor of different concentrations (10–200 ppm) at temperatures between room and 450 °C. The sensors showed stable and reproducible response at optimum operating temperatures. High sensor response towards vaporized ethanol as well as fast τres and τrec was observed during the “adsorption” and “desorption” interval. The recorded maximum response for these devices when exposed towards 100 ppm ethanol was measured to be 8 (Ro = 4.6 kΩ), 5.8 (Ro = 22.5 GΩ), and 5 (Ro = 0.29 MΩ) for HNO3, H3PO4, and H2SO4, respectively. The optimum operating temperatures were determined to be 400, 300–380, and 360 °C for the sensors developed using HNO3, H3PO4, and H2SO4, respectively.

We report on ethanol (C 2 H 5 OH) vapour sensing devices based on nanostructured cupric oxide (CuO) and cuprous oxide (Cu 2 O) thin films, which are deposited using RF sputtering at relatively low temperature and power conditions: at 120 °C, single stoichiometry CuO and Cu 2 O films are deposited using the sputtering power of 200 and 250 W, respectively. At such sputtering conditions CuO films exhibit smaller nanocrystallite base dimensions (∼30 nm), in comparison to Cu 2 O films (∼85 nm), which significantly enhance surface area to volume ratio. Both nanostructured CuO and Cu 2 O gas sensors are able to detect ethanol vapour as low as several ppm and at relatively low operating temperatures of 180 and 260 °C, respectively. The sensors showed high sensitivity and repeatability, as well as fast response and recovery towards ethanol vapour.

Herein, we present the novel synthesis of tetrahedrite copper antimony sulfide (CAS) nanocrystals (Cu12Sb4S13), which display strong absorptions in the visible and NIR. Through ligand tuning, the size of the Cu12Sb4S13 NCs may be increased from 6 to 18 nm. Phase purity is achieved through optimizing the ligand chemistry and maximizing the reactivity of the antimony precursor. We provide a detailed investigation of the optical and photoelectrical properties of both tetrahedrite (Cu12Sb4S13) and famatinite (Cu3SbS4) NCs. These NCs were found to have very high absorption coefficients reaching 10(5) cm(-1) and band gaps of 1.7 and 1 eV for tetrahedrite and famatinite NCs, respectively. Ultraviolet photoelectron spectroscopy was employed to determine the band positions. In each case, the Fermi energies reside close to the valence band, indicative of a p-type semiconductor. Annealing of tetrahedrite CAS NC films in sulfur vapor at 350 °C was found to result in pure famatinite NC films, opening the possibility to tune the crystal structure within thin films of these NCs. Photoelectrochemistry of hydrazine free unannealed films displays a strong p-type photoresponse, with up to 0.1 mA/cm(2) measured under mild illumination. Collectively these optical properties make CAS NCs an excellent new candidate for both thin film and hybrid solar cells and as strong NIR absorbers in general.

A series of ruthenium(II) polypyridyl complexes, with novel silane functionalisation, [Ru(bipy)2(bipy-sil)](PF6)2 (3), [Ru(bipy-sil)2Cl2] (6), and [Ru(bipy-sil)2(NCS)2] (7) have been synthesised and tested as chromophores (dyes) in TiO2 and WO3 based dye-sensitised solar cells (DSSCs). The performance of the respective DSSCs were compared to analogous dyes with ionic carboxylate ([Ru(bipy)2(dcbipy)](PF6)2 (1), [Ru(dcbipy)2Cl2] (4), [Ru(dcbipy)2(NCS)2] (5)) or phosphonate ([Ru(bipy)2(dpipy)](PF6)2 (2)) linking groups. The covalent silane–metal oxide linkage offers much needed improvement to the operating conditions, and lifetime of DSSCs, in terms of pH range and choice of solvent. UV–Vis spectroscopy of the deep-red solutions showed that the bis-bipy-sil complexes absorbed more visible light than the tris-bipy complex, as indicated by the presence of two absorption bands and higher e values. The UV–Vis spectrum of (3) contained a single broad absorption at 400–600 nm with: λmax = 457 nm; e = 10 520 ± 440 L mol−1 cm−1, whereas two intense broad absorption bands were observed for novel bis-bipy-sil complexes (6): 340–370 nm (λmax(1) = 365 nm, e(1) = 12 716 ± 180 L mol−1 cm−1); and 440–540 nm (λmax(2) = 485 nm, e(2) = 11 070 ± 150 L mol−1 cm−1), and (7): 340–400 nm (λmax = 371 nm, e(1) = 20 690 ± 485 L mol−1 cm−1), and 460–530 nm (λmax = 500 nm and e(2) = 20 750 ± 487 L mol−1 cm−1). The bands in (7) being significantly more defined. A 10-fold improvement in the efficiency of the bipy-sil TiO2-based DSSCs was observed from (3) to (6) to (7). This performance was lower than that of the commercial N3 dye, [Ru(dcbipy)2(NCS)2] (5), but the current of (7) on WO3, was comparable to that of the carboxylate system (4). There is considerable potential for further improvement by modification of the silyl linker, reducing the long non-conjugated propyl chain between the amide group and the silatrane (bipy-sil), to a short, conjugated link. During an extensive synthetic study, the most promising strategy was identified as direct linkage, the formation of a direct Si–C bond, using butyllithium with 4,4′-dibromo-2,2′-bipyridine and either trimethylsilane or 1-ethoxysilatrane, provided that the product can be captured and stabilised prior to binding to a metal oxide coated DSSC substrate.

This comprehensive review surveys developments over the past decade in the field of naphthalene diimides (NDIs). It explores their application toward: supramolecular chemistry; sensors; host–guest complexes for molecular switching devices, such as catenanes and rotaxanes; ion-channels by ligand gating; gelators for sensing aromatic systems; catalysis through anion−π interactions; and NDI intercalations with DNA for medicinal applications. We have also explored new designs, synthesis, and progress in the field of core-substituted naphthalene diimides (cNDIs), and their implications in areas such as artificial photosynthesis and solar cell technology. Also presented are some interesting synthetic routes and procedures that can be used toward further development of NDI-bearing compounds for future applications. Finally, we conclude with our views on NDI chemistry for future research endeavors, and we outline what we believe are the key obstacles that need to be overcome for NDIs to see real world applications.

Few-layer two-dimensional (2D) molybdenum oxide nanoflakes are exfoliated using a grinding assisted liquid phase sonication exfoliation method. The sonication process is carried out in five different mixtures of water with both aprotic and protic solvents. We found that surface energy and solubility of mixtures play important roles in changing the thickness, lateral dimension, and synthetic yield of the nanoflakes. We demonstrate an increase in proton intercalation in 2D nanoflakes upon simulated solar light exposure. This results in substoichiometric flakes and a subsequent enhancement in free electron concentrations, producing plasmon resonances. Two plasmon resonance peaks associated with the thickness and the lateral dimension axes are observable in the samples, in which the plasmonic peak positions could be tuned by the choice of the solvent in exfoliating 2D molybdenum oxide. The extinction coefficients of the plasmonic absorption bands of 2D molybdenum oxide nanoflakes in all samples are found to be high (ε10(9) L mol(-1) cm(-1)). It is expected that the tunable plasmon resonances of 2D molybdenum oxide nanoflakes presented in this work can be used in future electronic, optical, and sensing devices.

Cosmetic foundation powders are one of the most commonly used cosmetic products in modern society. In recent years, the so-called mineral-based foundation products have become increasing popular in the cosmetic consumer market and can demand a premium price from the consumer. Manufacturers and suppliers often refer to mineral foundations as being 'chemical free', implying that these materials contain no potential skin irritants. However, there are no laws determining the use of the term 'mineral cosmetic' and interpretation of the use of the term is at the discretion of the manufacturer. In this study, wavelength-dispersive X-ray fluorescence spectrometry has been employed for multi-elemental analysis of 39 mineral and traditional ingredient cosmetic powders. Quantitative measurements were obtained for Al, Bi, Ca, Fe, K, Mg, Si, Ti and Zn. Using cluster analysis and principal components analysis, we could clearly identify the samples as being of traditional or mineral formulation, and in the case of the mineral samples, specific manufacturers could be distinguished. Of the samples examined, samples from two suppliers marketed as mineral-based were determined as being indistinguishable from traditional formulations.

α- and β-Phase MoO3 are synthesized using an electrodeposition method on fluorine-doped tin oxide (FTO) glass substrates from sodium-molybdate (Na2MoO4) solutions. We show that it is possible to obtain both α- and β-MoO3 by manipulating the cyclic voltammetry (CV) parameters during electrodeposition. Raman spectroscopy, X-ray diffraction, and scanning electron microscopy indicate that the applied potential range and sweep rate are strongly influential on the phase obtained and the surface morphology of the electrodeposited thin films. Gasochromic measurements were carried out on the annealed samples by exposing them to H2 gas. It was revealed that α-MoO3 thin films provided better response to H2 interaction than β-MoO3 films did. Additionally, porous films provided significantly larger responses than smooth films.

Ab initio calculations carried out on the Tb analogue of the single-molecule magnet family Na9[Ln(W5O18)2] (Ln = Nd, Gd, Ho and Er) have allowed interpretation of the inelastic neutron scattering spectra. The combined experimental and theoretical approach sheds new light on the sensitivity of the electronic structure of the Tb(iii) ground and excited states to small structural distortions from axial symmetry, thus revealing the subtle relationship between molecular geometry and magnetic properties of the two isostructural species that comprise the sample.

Highly dispersed gold nanoparticles (AuNPs) supported on nitrogen-doped multiwalled carbon nanotubes (NCNTs) were synthesized using an electrochemical method. Size of AuNPs and their dispersion profile were tuned in a facile manner by controlling the applied potential and deposition time. The structure of the films was characterized using SEM, HRTEM, XRD and Raman spectroscopy. Electron microscopy revealed that the nanoparticles were deposited homogeneously on the outer surface of the NCNTs in high density. The average dimensions of the AuNPs could be tuned by varying the applied voltage and the duration of the electrochemical process. The XRD patterns confirmed the presence of metallic fcc gold along with disordered graphitic phases. The Raman spectroscopy showed that NCNTs possess 3–5 at.% nitrogen with a heterogeneous distribution profile, which is consistent with nitrogen incorporation in both graphitic and pyridinic moieties within the carbon sp 2 network of disordered NCNTs. SERS enhancement was also observed for AuNPs/NCNTs prepared at 10 V/20 min condition. Conductometric gas sensors were developed from the thin films of AuNPs/NCNTs nanocomposites and evaluated towards H 2 gas. The sensors were exposed to different concentrations of H 2 in synthetic air at room temperature. The highest sensitivity of 75% was measured towards 1% H 2 when average size of AuNPs on NCNTs is about 4–6 nm.

The synthesis and crystal structure elucidation of two novel polymeric copper(II) complexes has led us to propose a mechanism for the formation of 2-picolinic acid (pic) from di-2-pyridyl ketone (dpk) and benzoic acid from acetophenone. During studies into the interaction of copper ions with the dpk-acetophenone system, two complexes Na2(NCS)2(H2O)[Cu(pic)2] (1) and Na2(H2O)2[Cu(pic)2(NCS)2] (2) which contain pic coordinated to copper were isolated. The occurrence of (1) and (2) has led us to consider the Baeyer–Villiger rearrangement as a possible mechanism for the formation of (1) and (2).

Exothermic chemical reactions that are coupled to Bi2Te3 porous layers, which are deposited onto terracotta or alumina (Al2O3) substrates, are used to produce self-propagating thermal waves that are guided along the surface. Nitrocellulose is used as the highly reactive chemical. Bi2Te3 is employed because of its large Seebeck coefficient and high electrical conductivity. For the Al2O3 based structures, the thermal conduction of the substrate results in strong oscillations of the output signals. Such thermopower waves produce a power as large as 10 mW and voltages as high as 150 mV. The power per mass ratio of the developed system is quite remarkable, namely, on the order of 1 kW kg(-1). Depending on the thermal conductivity of the substrate used, the wave front average propagation velocity is either slow (ca. 0.009 m s(-1) for terracotta) or much faster (on the order of 0.4 m s(-1) for Al2O3). We have used a mathematical model based on two coupled heat transport equations, in conjunction with the chemical reaction equation, to predict the behavior of the system, which describes the average propagation velocity and the time between oscillation peaks.

In this paper, we report the development of novel Pt/nanostructured RuO2/SiC Schottky diode based sensors for hydrogen gas applications. The nanostructured ruthenium oxide thin films were deposited on SiC substrates using radio frequency sputtering technique. Scanning electron microscopy revealed the sputtered RuO2 layer consists of nano-cubular structures with dimensions ranging between 10 and 50 nm. X-ray diffraction confirmed the presence of tetragonal ruthenium (IV) oxide, with preferred orientation along the (101) lattice plane. The current-voltage characteristics of the sensors were investigated towards hydrogen gas in synthetic air at different temperatures from 25 °C to 240 °C. The dynamic responses of the sensors were studied at an optimum temperature of 240 °C and a voltage shift of 304 mV was recorded toward 1% hydrogen gas.

In this work, molybdenum trioxide (MoO3) nanostructured films were deposited onto quartz substrates via thermal evaporation of MoO3 powder. Subsequently, a catalytic palladium (Pd) layer was deposited onto MoO3 layer by e-beam evaporation. Scanning electron microscopy (SEM) revealed MoO3 nanorods grown in various directions and X-ray diffraction (XRD) confirmed the growth of orthorhombic MoO3. Optical hydrogen (H2) sensing performance of nanostructured Pd/MoO3 films were investigated at a concentration between 0.06-1%. It was observed that the nanostructured films exhibited excellent gasochromic characteristics and remarkable absorbance changes in near infrared (NIR) wavelength range (750-1000 nm) when exposed to H2. Pd/MoO3 T90% response and recovery towards 0.06% H2 were 150 and 300 s, respectively. The film operating temperature was also found as low as 120 °C.

Pt/nanostructured WO3/SiC Schottky diodes were fabricated and applied for hydrogen gas sensing applications. The nanostructured WO3 films were synthesized from tungsten coated SiC substrates via an acid-etching method using a 1.5 M HNO3 solution for 1hr, 2hrs and 3hrs duration. Scanning electron microscopy of the developed films revealed platelet crystals with thicknesses in the order of 2Q-60 nm and lengths between 10Q-700 nm. X-ray diffraction analysis revealed that the rate of oxidation of tungsten increases as the duration of acid-etching increases. The devices were tested towards hydrogen gas balanced in air at different temperatures from 25c to 200c. At 200c, voltage shifts of 0.45 V, 0.93 V and 2.37 V were recorded for devices acid-etched for 1 hr, 2 hrs and 3 hrs duration, respectively upon exposure to 1% hydrogen, under a constant forward bias current of 500 nA.

The supramolecular interactions of the planar guanidinium cation ( C ( NH 2 ) 3 + ) with benzenesulphonate (1), -phosphonate (2) and -arsonate (3) anions, and several of their 3- and 4-nitro-substituted derivatives is reported. In all cases well-defined crystalline materials, containing hydrogen-bonded networks with quasi-hexagonal sheet lattices were formed. However, the unsubstituted sulphonate (1) formed a 1:1 guanidinium:sulphonate bilayer structure, whilst the unsubstituted phosphonate (2) and arsonate (3) formed 2:1 guanidinium:phosphonate/arsonate single-layer structures with water occluded within the crystal voids. The additional H-bonding interactions resulting in distortion of the crystal voids in (2)/(3) as compared to the symmetrical hexagonal-form in (1). In the case of the nitro-substituted sulphonate derivatives, the 1:1 bilayer structure of the parent (1) was retained for the 3-nitrobenzenesulphonate (4), but transformed to a 1:1 single-layer system for the 4-nitrobenzenesulphonate (6). The reverse was observed for the nitrated phosphonic acids, whereby the 4-nitrobenzenephosphonate anion in (5) caused little disruption to the 2:1 single-layered structure and quasi-hexagonal sheet seen in (2), but the 3-nitrobenzenephosphonate caused a breakdown of the network forming a new, complex ribbon system (7). The greater complexity of the P/As (−2) structures compared to the S (−1) structure is attributed to the higher charge on the former anions providing additional opportunities for H-bonding. The observation of such interactions clearly indicates the likelihood of such species interacting with biologically-important arginine residues in vivo with concomitant unintended, but likely, toxic consequences.

Nanosturctured WO 3 films were synthesized via anodization at elevated temperature. Nitric acid (HNO 3 ) and sulfuric acid (H 2 SO 4 ) were employed for the first time. Different nanostructured morphologies were observed. The novel conductometric H2 gas sensor has been developed based on these WO3 films. The sensor with anodized WO3 film in HNO 3 exhibited high sensitivity towards H2 as low as 0.06% at relatively low operating temperature (120 °C).

Complexes containing di(2-pyridyl) ketone (dpk) as a bi- (N,N) and tridentate (N,N,O) ligand have been synthesised1,2 and characterized by spectral and structural studies. Products 1 and 2 are polymorphs of the polymeric copper(I) complex [Cu(dpk)(NCS)]n containing dpk with thiocyanate anions which bridge to form a one-dimensional continuous polymer chain. The novel dinuclear copper(II) complex [Cu2(dpk·acetone) 2(NCS)2] (3) was formed when 1 and 2 were allowed to stand in the supernatant. In this instance it appears that a transition-metal- promoted aldol condensation has occurred between the solvent acetone and the ketone carbonyl of dpk to produce the novel ligand, dpk·acetone. Product 3 contains two five-coordinate copper(II) ions, both with trigonal bipyramidal coordination, bridged through deprotonated hydroxy groups on each dpk·acetone. A chemical rationalisation for the formation of 3 is proposed. The dinuclear copper(I) complex [Cu2(dpk)2I 2] (4) is also reported, which contains two four-coordinate copper(I) ions that are bridged together through iodide ions.

Energetic deposition of high speed steel (HSS) films has been performed using a filtered cathodic vacuum arc system fitted with a AISI M2 HSS cathode. The mechanical properties and microstructure of the films were investigated as a function of the deposition energy. The stoichiometry and microstructure of the deposited films were different to that of the cathode and a dependence on the deposition energy was found. Films deposited at low deposition energies (< 100 eV) exhibited reduced concentrations of Mo and W and a smaller average crystallite size than the M2 HSS cathode. These films were found to be significantly harder than the M2 HSS cathode, possibly due to their smaller average crystallite size. A HSS film consisting of an amorphous phase with isolated crystals of bcc Fe was produced using high deposition energy and the deposition rate was found to decrease, likely due to sputtering.

In this work, MoO 3 was thermally evaporated onto gold interdigital fingers on quartz substrates and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The deposited MoO 3 consist of stratified long rectangles (average length of 50 μm width of 5 μm and thickness of 500 nm) which are predominantly orthorhombic (α-MoO 3 ). Each of these plates was composed of many nano-thick layers (average ∼30 nm) placed by Van der Waals forces on top of each other forming lamellar patterns. The devices were used as sensors and exhibited considerable change in surface conductivity when exposed to NO 2 and H 2 gases at elevated temperature of 225 °C. The structural and gas sensing properties of thermally evaporated MoO 3 thin films were investigated.

The synthesis and crystal structure elucidation of a novel dinuclear heteroleptic copper(II) complex has led to an alternative mechanism in the formation of covalent hydrates. During further studies on the synthesis and properties of [Cu(2)(ophen)(2)] (1), a dinuclear complex of copper(I) with 1 H-[1,10]-phenanthrolin-2-one (Hophen), two intermediates/alternative products 2 and 3 were isolated. The dinuclear, antiferromagnetic complex [Cu(2)(ophen)(2)(phen)(2)](NO(3))(2)9H(2)O (3, phen=1,10-phenanthroline) contains two five-coordinate copper(II) ions, both with trigonal-bipyramidal coordination, which are bridged together through deprotonated hydroxyl groups with a Cu--Cu non-bonding distance of 3.100 A. Complex [Cu(phen)(2)(H(2)O)](NO(3))(2) (2) is a polymorph of a previously reported material. The occurrence of 2 and 3 has led us to propose a variation to the Gillard mechanism for the formation of covalent hydrates in bidentate N-heterocycles in which the attacking nucleophile may be the deprotonated form of 2, [Cu(phen)(2)(OH)](-), rather than free OH(-).

Optical gas sensing performance of nanoporous TiO2 films coated with catalytic Pd layer was investigated for low concentration H2 sensing. Nanoporous TiO2 films were obtained from anodization of DC sputtered titanium (Ti). The Ti films were deposited onto quartz and subsequently anodized at room temperature and annealed at 800°C. Highly homogeneous arrays of nanopores having diameters in the range of 15-25nm were observed. It was found that the Pd/TiO2 nanoporous films show remarkable optical absorbance response towards H2 as low as 0.06%. The optimum operating temperature of the nanoporous films for H2 sensing was found to be very low (60°C).

The structural, optical, and gas-sensing properties of spray pyrolysis deposited Cu doped ZnO thin films were investigated. Gas response of the undoped and doped films to NO2 (oxidizing) gas shows an increase and decrease in resistance, respectively, indicating p-type conduction in doped samples. The UV-Vis spectra of the films show decrease in the bandgap with increasing Cu concentration in ZnO. The observed p-type conductivity is attributed to the holes generated by incorporated Cu atoms on Zn sites in ZnO thin films. The X-ray diffraction spectra showed that samples are polycrystalline with the hexagonal wurtzite structure and increasing the concentration of Cu caused a decrease in the intensity of the dominant (002) peak. The surface morphology of films was studied by scanning electron microscopy and the presence of Cu was also confirmed by X-ray photoelectron spectroscopy. Seebeck effect measurements were utilized to confirm the p-type conduction of Cu doped ZnO thin films.

Anodization at elevated temperatures in nitric acid has been used for the production of highly porous and thick tungsten trioxide nanostructured films for photosensitive device applications. The anodization process resulted in platelet crystals with thicknesses of 20-60 nm and lengths of 100-1000 nm. Maximum thicknesses of approximately 2.4 microm were obtained after 4 h of anodization at 20 V. X-ray diffraction analysis revealed that the as-prepared anodized samples contain predominantly hydrated tungstite phases depending on voltage, while films annealed at 400 degrees C for 4 h are predominantly orthorhombic WO3 phase. Photocurrent measurements revealed that the current density of the 2.4 microm nanostructured anodized film was 6 times larger than the nonanodized films. Dye-sensitized solar cells developed using these films produced 0.33 V and 0.65 mA/cm2 in open- and short-circuit conditions.

Ti films sputtered on transparent fluorine-doped tin oxide glass substrates were anodized in fluoride-containing organic electrolyte in the presence of H2O. In this work, anodic TiO2 nanotubes (ATNs) as long as 9.2 ± 0.3 μm were obtained with high growth rate of 0.64 ± 0.3 μm min−1. We demonstrated the optimum anodization conditions for ATN growth on foreign substrates, were within the range of 0.3–0.5% (wt) NH4F, with 3–5% (vol) H2O at 60 V. XPS and ICP-MS were utilized to elucidate the increase of thickness and volume expansion obtained from the sputtered Ti film to their ATN forms. The ATN films exhibited excellent uniformity and adhesion to the substrates. Keywords: Anodic TiO2 nanotubes, Volume expansion, TCO, Sputtered Ti