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Gas storage and recovery processes in shales critically depend on nano-scale porosity and chemical composition, but information about the nanoscale pore geometry and connectivity of kerogen, insoluble organic shale matter, is largely unavailable. Using adsorption microcalorimetry, we show that once strong adsorption sites within nanoscale network are taken, gas adsorption even at very low pressure is governed by pore width rather than chemical composition. A combination of focused ion beam with scanning electron microscopy and transmission electron microscopy reveal the nanoscale structure of kerogen includes not only the ubiquitous amorphous phase but also highly graphitized sheets, fiber- and onion-like structures creating nanoscale voids accessible for gas sorption. Nanoscale structures bridge the current gap between molecular size and macropore scale in existing models for kerogen, thus allowing accurate prediction of gas sorption, storage and diffusion properties in shales. Engineering and Physical Sciences Research Council (EPSRC)UK Research & Innovation (UKRI)Engineering & Physical Sciences Research Council (EPSRC) [EP/M000567/1]; EPSRCUK Research & Innovation (UKRI)Engineering & Physical Sciences Research Council (EPSRC) [EP/L022494/1, EP/R024790/1]; University of Nottingham We would like to thank Dr. Elisabeth Steer at Nanoscale & Microscale Research Centre for providing training in SEM-MLA and technician team (David Mee and Dr. Jacob Uguna) at the Faculty of Engineering, University of Nottingham for assistance with hydrofluoric acid digestion. Funding: Gas Adsorption Analysis Suit equipment funded by the Engineering and Physical Sciences Research Council (EPSRC, EP/M000567/1), FIB-SEM and TEM work was supported by the EPSRC (EP/L022494/1) and the University of Nottingham. A. Khlobystov acknowledges EPSRC for funding (Established Career Fellowship EP/R024790/1), C. Vane publishes with permission of the Executive Director, British Geological Survey (UKRI).

Reactivity of a series of related molecules under the 80 keV electron beam have been investigated and correlated with their structures and chemical composition. Hydrogenated and halogenated derivatives of hexaazatrinaphthylene, coronene, and phthalocyanine were prepared by sublimation in vacuum to form solventless crystals then deposited onto transmission electron microscopy (TEM) grids. The transformation of the molecules in the microcrystals were triggered by an 80 keV electron beam in the TEM and studied using correlated selected area electron diffraction, conventional bright field imaging, and energy dispersive X-ray spectroscopy. The critical fluence (ē nm

Fringe analysis is a commonly used method to quantify soot nanostructures. However, the settings of the involved filters and their impact on the results are rarely addressed. In this study, the influence of the three filter parameters as well as two aspects of the image acquisition was assessed experimentally. For the analysis, a carbon black as well as one diesel engine and one gasoline direct injection (GDI) engine soot sample were used. Gaussian low-pass filter standard deviations larger 1.5 yielded only minor differences in fringe metrics. Standard deviations between 2.0 and 3.0 enabled realistic representation of fringes. A linear correlation was found between the white top-hat transformation disk size and all fringe analysis metrics. For realistic nanostructure representation, disk sizes of 5 px and 7 px are most suitable. Threshold values as calculated by Otsu's method generally yielded the best nanostructure representation. Any deviation distorted the extracted fringes and noticeably reduced their total number. Thus, consistent use of Otsu thresholds without alterations is advised. Deviating from the neutral electron microscope focus point by under- and over-focusing resulted in distinctive drops in both fringe lengths and Otsu thresholds. Consistent focusing with the help of fast Fourier transformations of the respective particles is vital for reliable results. The effect of reduced noise levels by repeated averaged images was found to be minor beyond the model of the camera used. The region of interest size correlated linearly with the number of extracted fringes, however, it did not affect the fringe metrics. For statistically reliable analysis, a minimum of 4000 fringes is suggested. The GDI sample exhibited the shortest fringes and the highest tortuosity. For diesel soot and carbon black, similar fringe lengths could be observed. The highest tortuosity was found for GDI soot, followed by diesel soot and carbon black.

Enzyme-based treatments are used in heritage conservation for the effective removal of glues and other damaging organic layers from the surfaces of historic and artisitc works. Despite their potential, however, the application of enzymatic treatments is currently limited due to their poor efficiency, and low operational and environmental stability. We demonstrate the use of α-amylase immobilized on gold nanoparticles to improve the efficacy of enzymatic treatments enchancing both the reactivity and the stability of the formulations. Gold nanoparticles coated with α-amylase exhibit significant advantages compared to free enzymes. We report up to 5-times greater resistance to environmental changes, up to 2-times higher efficacy towards removal of starch-based glues from textile, and deeper penetration through the fibres, without causing damage or inducing salt precipitation. These results offer exciting prospects for the development of novel enzymatic formulations, both for heritage conservation and the wider application of enzymes, such as in medicine, the detergent industry and green chemistry.

Electron energy-loss spectroscopy (EELS) is a technique that can give useful information on elemental composition and bonding environments. However in practice, the complexity of the background contributions, which can arise from multiple sources, can hamper the interpretation of the spectra. As a result, background removal is both an essential and difficult part of EELS analysis, especially during quantification of elemental composition. Typically, a power law is used to fit the background but this is often not suitable for many spectra such as in the low-loss region (< 50 eV) and when there are overlapping EELS edges. In this article, we present a series of scripts written in MATLAB v. R2019b that aims to provide statistical information on the model used to fit the background, allowing the user to determine the accuracy of background subtraction. The scripts were written for background subtraction of vibrational EELS in the ultralow-loss region near the zero-loss peak but can also be applied to other kinds of EEL spectra. The scripts can use a range of models for fitting, provided by the Curve Fitting Toolbox of MATLAB, and the user is able to precisely define the window for fitting as well as for edge integration. We demonstrate the advantages of using these scripts by comparing their background subtraction of example spectra to the most commonly used software, Gatan Microscopy Suite 3. The example spectra include those containing multiple scattering, multiple overlapping peaks, as well as vibrational EELS. Additionally, a comprehensive guide to using the scripts has been included in the Supplementary Information.

Glioblastoma is a malignant brain tumour with a median survival of 14.6 months from diagnosis. Despite maximal surgical resection and concurrent chemoradiotherapy, reoccurrence is inevitable. To try combating the disease at a stage of low residual tumour burden immediately post-surgery, we propose a localised drug delivery system comprising of a spray device, bioadhesive hydrogel (pectin) and drug nanocrystals coated with polylactic acid-polyethylene glycol (NCPPs), to be administered directly into brain parenchyma adjacent to the surgical cavity. We have repurposed pectin for use within the brain, showing in vitro and in vivo biocompatibility, bio-adhesion to mammalian brain and gelling at physiological brain calcium concentrations. Etoposide and olaparib NCPPs with high drug loading have shown in vitro stability and drug release over 120 h. Pluronic F127 stabilised NCPPs to ensure successful spraying, as determined by dynamic light scattering and transmission electron microscopy. Successful delivery of Cy5-labelled NCPPs was demonstrated in a large ex vivo mammalian brain, with NCPP present in the tissue surrounding the resection cavity. Our data collectively demonstrates the pre-clinical development of a novel localised delivery device based on a sprayable hydrogel containing therapeutic NCPPs, amenable for translation to intracranial surgical resection models for the treatment of malignant brain tumours.

Magnetosomes are nano-sized magnetic nanoparticles with exquisite properties that can be used in a wide range of healthcare and biotechnological applications. They are biosynthesised by magnetotactic bacteria (MTB) such as Magnetospirillum gryphiswaldense MSR-1 (Mgryph). However, magnetosome bioprocessing yields low quantities compared to chemical synthesis of magnetic nanoparticles. Therefore, the understanding of the intracellular metabolites and the metabolic networks related to Mgryph growth and magnetosome formation are vital to unlock the potential of this organism to develop improved bioprocesses. In this work, we investigated the metabolism of Mgryph using untargeted metabolomics. Liquid chromatography-mass spectrometry (LC-MS) was performed to profile spent medium samples of Mgryph cells grown under O2-limited (n=6) and O2-rich conditions (n=6) corresponding to magnetosome- and non-magnetosome producing cells, respectively. Cross-validated multivariate, univariate and pathway enrichment analyses were conducted to identify significantly altered metabolites and pathways. Rigorous metabolite identification was carried out using authentic standards, Mgryph-specific metabolite database and MS/MS mzCloud database. PCA and OPLS-DA showed clear separation and clustering of sample groups with cross-validation values of R2X=0.76, R2Y=0.99 and Q2=0.98 in OPLS-DA. As a result, 50 metabolites linked to 45 metabolic pathways were found significantly altered in the tested conditions including glycine, serine and threonine; butanoate; alanine, aspartate and glutamate metabolism; aminoacyl-tRNA biosynthesis and; pyruvate and citric acid cycle (TCA) metabolisms. Our findings demonstrate the potential of LC-MS to characterise key metabolites in Mgryph and will contribute to further understand the metabolic mechanisms that affect Mgryph growth and magnetosome formation.

Magnetosomes are nano-sized magnetic nanoparticles with exquisite properties that can be used in a wide range of healthcare and biotechnological applications. They are biosynthesised by magnetotactic bacteria (MTB), such as

The use of single-walled carbon nanotubes as effective nanoreactors for preparative bimolecular reactions has been demonstrated for the first time. We show that the extreme spatial confinement of guest reactant molecules inside host carbon nanotubes increases the regioselectivity for 1,4-triazole in thermally initiated azide–alkyne cycloaddition reactions. Through comparison of the internal dimensions of the nanotube and the steric bulk of the reactants, we demonstrate that the formation of the more linear 1,4-regioisomer can be enhanced by up to 55% depending on the extent of spatial restrictions imposed within the nanoreactors. Furthermore, through systematic variation of the substituents in the para-position of the alkyne reactants, we reveal the unexpected influence of the reactants’ electronic properties on the regioselectivity of reactions within nanoreactors, which act to either oppose or promote the preferential formation of the 1,4-regioisomer induced by steric effects, reflecting the unique ability of carbon nanotubes to stabilize the dipole moment of confined reactants. Thus, we show that the observed regioselectivity of azide–alkyne cycloaddition reactions confined within carbon nanotube nanoreactors reflects a subtle interplay between both steric and electronic factors.

Metal oxide microparticles with well-defined internal mesostructures are promising materials for a variety of different applications, but practical routes to such materials that allow the constitue...

A dehydrative cross-coupling of 1-phenylethanol catalysed by sugar derived, in situ formed palladium(0) nanoparticles under acidic conditions is realised. The acidic conditions allow for use of alcohols as a feedstock in metal-mediated coupling reactions via their in situ dehydration and subsequent cross-coupling. Extensive analysis of the size and morphology of the palladium nanoparticles formed in situ showed that the zero-valent metal was surrounded by hydrophilic hydroxyl groups. EDX-TEM imaging studies using a prototype silicon drift detector provided insight into the problematic role of molecular oxygen in the system. This increased understanding of the catalyst deactivation allowed for the development of the cross-coupling methodology. A 250-12,000 fold increase in molar efficiency was observed when compared to related two-step protocols that use alternative feedstocks for the palladium-mediated synthesis of stilbenes. This work opens up a new research area in which the active catalyst is formed, stabilised and regenerated by a renewable sugar.

The aim of this work is to make progress towards the development of 3D reconstruction as a legitimate alternative to traditional 2D characterisation of soot. Time constraints are the greatest opposition to its implementation, as currently reconstruction of a single soot particle takes around 5-6 hours to complete. As such, the accuracy and detail gains are currently insufficient to challenge 2D characterisation of a representative sample (e.g. 200 particles). This work is a consideration of the optimisation of the steps included within the computational reconstruction and manual segmentation of soot particles. Our optimal process reduced the time required by over 70% in comparison to a typical procedure, whilst producing models with no appreciable decrease in quality.

Two- and three-coordinate manganese m-terphenyl complexes are precatalysts for the dehydrogenation of dimethylamine-borane (Me2NH·BH3) affording one equivalent of molecular hydrogen and half an equivalent of [Me2N–BH2]2. Experimental studies into the nature of the catalyst indicate that small changes in the coordination environment give rise to significant differences in the reaction mechanism, occurring through a homogeneous mechanism for two-coordinate precatalysts, whilst for the three-coordinate species a heterogeneous mechanism takes place where nanoparticles are responsible for the catalysis.

The confinement and enhanced catalytic properties of hydroxylated group IV metal oxide nanostructures inside hollow graphitised carbon nanofibers (GNF) has been demonstrated. GNF – a structural analogue of carbon nanotubes – were effectively filled with suitable precursor molecules of metal chlorides from the gas and liquid phases. Subsequent base-catalysed hydrolysis afforded amorphous, nanostructured hydroxylated metal oxide (MOx(OH)y where M = Zr, Ti, and Hf) thin films, which coat the internal surfaces of GNF. This versatile and general strategy allows the chemical composition and morphology of the encapsulated material to be modified by varying the conditions used for hydrolysis and post-synthesis thermal treatment. The increased Lewis acidic properties and high surface area of the zirconium composite promote the catalysed hydrolysis of dimethyl nitrophenyl phosphate (DMNP) – a toxic organophosphorus chemical. A four-fold enhancement in the rate of DMNP hydrolysis relative to its separate constituent components was observed, highlighting the surprising synergistic abilities of this composite material to perform both as a ‘nano-sponge’, absorbing the harmful compounds inside the GNF, and a nanoreactor, enhancing the local concentration of organophosphate around the hydroxylated metal oxide species, leading to improved catalytic performance.

Comparison of electric discharge (ED) processed single deposit and continuum TiC-Fe cermet coatings, formed from a sacrificial powder metallurgy TiC tool electrode at negative polarity, on 304 stainless steel, provided insight into the ED coating (EDC) formation mechanism. A deposit from a single spark event was dominated by TiC, phase separated from a ∼2 wt% Fe matrix, with strongly aligned grains and banded microstructure, indicative of solidification from the coating/substrate interface. Conversely, a continuum coating, subjected to ∼200 spark events per location, exhibited a more complex, banded microstructure, with a mixture of equiaxed and columnar TiC grains within a ∼30 wt% Fe-based matrix, along with some concentrations of carbon from the oil dielectric. It is considered that each sparking event remelts previously solidified coating material, with or without further TiC particle incorporation, leading to gradual TiC dilution and the development of a TiC-Fe composite coating with increasing levels of substrate material forming the matrix.

We report on the synthesis of water-soluble gold nanoclusters capped with polyethylene glycol (PEG)-based ligands and further functionalized with folic acid for specific cellular uptake. The dihydrolipoic acid-PEG-based ligands terminated with -OMe, -NH2 and -COOH functional groups are produced and used for surface passivation of Au nanoclusters (NCs) with diameters

Despite important advances in the synthesis of inorganic perovskite nanocrystals (NCs), the long-term instability and degradation of their quantum yield (QY) over time need to be addressed to enable the further development and exploitation of these nanomaterials. Here we report stable CsPbI

Despite important advances in the synthesis of inorganic perovskite nanocrystals (NCs), the long-term instability and degradation of their quantum yield (QY) over time need to be addressed to enable the further development and exploitation of these nanomaterials. Here we report stable CsPbI3 perovskite NCs and their use in hybrid light emitting diodes (LEDs), which combine in one system the NCs and a blue GaN-based LED. Nanocrystals with improved morphological and optical properties are obtained by optimizing the post-synthesis replacement of oleic acid ligands with iminodibenzoic acid: the NCs have a long shelf-life (>2 months), stability under different environmental conditions, and a high QY, of up to 90%, in the visible spectral range. Ligand replacement enables the engineering of the morphological and optical properties of the NCs. Furthermore, the NCs can be used to coat the surface of a GaN-LED to realize a stable diode where they are excited by blue light from the LED under low current injection conditions, resulting in emissions at distinct wavelengths in the visible range. The high QY and fluorescence lifetime in the nanosecond range are key parameters for visible light communication, an emerging technology that requires high-performance visible light sources for secure, fast energy-efficient wireless transmission.

Formation of soot is a known phenomenon for diesel engines, however, only recently emerged for gasoline engines with the introduction of direct injection systems. Soot-in-oil samples from a three-cylinder turbo-charged gasoline direct injection (GDI) engine have been analysed. The samples were collected from the oil sump after periods of use in predominantly urban driving conditions with start-stop mode activated. Thermogravimetric analysis (TGA) was performed to measure the soot content in the drained oils. Soot deposition rates were similar to previously reported rates for diesel engines, i.e. 1 wt% per 15,000 km, thus indicating a similar importance. Morphology was assessed by transmission electron microscopy (TEM). Images showed fractal agglomerates comprising multiple primary particles with characteristic core-shell nanostructure. Furthermore, large amorphous structures were observed. Primary particle sizes ranged from 12 to 55 nm, with a mean diameter of 30 nm and mode at 31 nm. Particle agglomerates were measured by nanoparticle tracking analysis (NTA). The agglomerates were found to range between 42 and 475 nm, with a mean size of 132 nm and mode at 100 nm. The distribution was shifted towards larger sizes with a minor concentration of very large agglomerates observed around 382 nm. While deposition rate and agglomerate morphology were similar to diesel engines, distinctive amorphous carbon and smaller particles were observed. Hence, existing knowledge for diesel applications might not be directly transferrable.

The preparation of inorganic nanomaterials with a desired structure and specific properties requires the ability to strictly control their size, shape and composition. A series of chemical reactions with platinum compounds carried out within the 1.5 nm wide channel of single-walled carbon nanotubes (SWNTs) have demonstrated the ability of SWNTs to act as both a very effective reaction vessel and a template for the formation of nanocrystals of platinum di-iodide and platinum di-sulphide, materials that are difficult to synthesise in the form of nanoparticles by traditional synthetic methods. The stepwise synthesis inside nanotubes has enabled the formation of Pt compounds to be monitored at each step of the reaction by aberration-corrected high resolution transmission electron microscopy (AC-HRTEM), verifying the atomic structures of the products, and by an innovative combination of fluorescence-detected X-ray absorption spectroscopy (FD-XAS) and Raman spectroscopy, monitoring the oxidation states of the platinum guest-compounds within the nanotube and the vibrational properties of the host-SWNT, respectively. This coupling of complementary spectroscopies reveals that electron transfer between the guest-compound and the host-SWNT can occur in either direction depending on the composition and structure of the guest. A new approach for nanoscale synthesis in nanotubes developed in this study utilises the versatile coordination chemistry of Pt which has enabled the insertion of the required chemical elements (e.g. metal and halogens or chalcogens) into the nanoreactor in the correct proportions for the controlled formation of PtI2 and PtS2 with the correct stoichiometry.

The integrated analytical approach developed in this study offers a powerful methodology for the structural characterisation of complex molecular nanomaterials. Structures of a covalent organic framework based on boronate esters (COF-5) and a conjugated microporous polymer (Aza-CMP) have been investigated by a combination of several electron microscopy techniques elucidating the three-dimensional topology of the complex polycrystalline (COF) and non-crystalline (CMP) materials. Unexpected, aperiodic mesoporous channels of 20-50 nm in diameter were found to be penetrating the COF and CMP particles, which cannot be detected by X-ray diffraction techniques. The mesopores appear to be stable under a range of different conditions and accessible to gas molecules, exhibiting a particular bonding capability with CO2 in the case of the CMP. The mesoporosity is unrelated to the intrinsic chemical structures of the COF or CMP but rather it reflects the mechanisms of polymer particle formation in a polycondensation reaction. The mesopores may be templated by clusters of solvent molecules during the COF or CMP synthesis, leaving cavities within the polymer particles. The unexpected mesoporosity discovered in COF and CMP materials begs for re-assessment of the nature of framework materials and may open new opportunities for applications of these molecular materials in gas sorption or catalysis. We acknowledge the support of the Engineering and Physical Science Research Council (EPSRC) for funding, and the Nanoscale and Microscale Research Centre (nmRC) for access to instrumentation. We are also grateful to the Basque Science Foundation for Science (Ikerbasque), POLYMAT, the University of the Basque Country (Grupo de Investigacion GIU17/054 and SGIker), Gobierno de Espana (Ministerio de Economia y Competitividad CTQ2016-77970-R, CTQ2017-83486-P and FPU16/04162), Gobierno Vasco (BERC program). This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no 664878. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreements 722951 and 714122).

Uniform, less 10?nm sized, hollow carbon nano-shells (HCNS) have been prepared via a single-step, thermal treatment of alkanethiol stabilised Ag nanoparticles (TS-AgNP). Direct evidence for the formation of spherical HCNS from TS-AgNP is provided by in situ MEMS heating on Si3N4 supports within a TEM, and ex situ thermal processing of TS-AgNP on carbon nanotube supports. A mechanism is proposed for the thermally driven, templated formation of HCNS from the TS-AgNP stabilising layer, with Ag catalysing the graphitisation of carbon in advance of thermally induced AgNP template removal. This facile processing route provides for excellent size control of the HCNS product via appropriate AgNP template selection. However, a rapid rate of heating was found to be crucial for the formation of well-defined HCNS, whilst a slow heating rate gave a much more disrupted product, comprising predominantly lacy carbon with decreased levels of graphitic ordering, reflecting a competition between the thermal transformation of the TS-layer and the rate of removal of the AgNP template.

Metal oxide microparticles with well-defined internal mesostructures are promising materials for a variety of different applications, but practical routes to such materials that allow the constituent structural length scales to be precisely tuned have thus far been difficult to realize. Herein, we describe a novel platform methodology that utilizes self-assembled block copolymer (BCP) microparticles synthesized by dispersion polymerization in supercritical CO

The evolution of individual palladium nanoparticle (PdNP) catalysts in graphitised nanofibres (GNF) in the liquid-phase Suzuki-Miyaura (SM) reaction has been appraised. The combination of identical location-transmission electron microscopy (IL-TEM) and a nano test tube approach allowed spatiotemporally continuous observations at the single nanoparticle level, revealing that migration and coalescence is the most significant pathway to coarsening of the nanocatalyst, rather than Ostwald ripening. IL-TEM gave unprecedented levels of detail regarding the movement of PdNP on carbon surfaces at the nanoscale, including size-dependent migration and directional movement, opening horizons for the optimisation of future catalysts through surface morphology design.

The size and morphology of soot particles and agglomerates extracted from lubricating oil drawn from the sump of a diesel engine have been investigated and compared using Transmission Electron Microscopy (TEM) and Nanoparticle Tracking Analysis (NTA). Samples were prepared for electron microscopy imaging by both centrifugation and solvent extraction to investigate the impact of these procedures on the morphological characteristics, such as skeleton length and width and circularity, of the obtained soot. It was shown that centrifugation increases the extent of agglomeration within the sample, with 15% of the agglomerates above 200 nm compared to only 11% in the solvent extracted soot. It was also observed that the width of centrifugation extracted soot was typically 10 nm to 20 nm larger than that of solvent extracted soot, suggesting that centrifugation forces the individual agglomerate chains together. Moreover, centrifugation fails to extract a large percentage of particles below 50 nm, with only 4% of the agglomerates smaller than 50 nm in the centrifugation extracted soot, whereas agglomerates in this size range accounted for 19 % using solvent extraction. As TEM represents a comparatively time and cost expensive characterisation tool, unsuitable for high throughput testing required by industry, NTA was explored as a low cost, rapid alternative method for measuring particle size. It was found that results generated by NTA, within the limits of detection, correlated well with those obtained using TEM. This correlative electron microscopy and light scattering approach was further used to appraise the morphological characteristics of two commercial sources of carbon black (CB), enabling the selection of the most suitable soot surrogate, essential for the further development of oils with optimised functional properties.

The preparation of thinned lamellae from bulk samples for transmission electron microscopy (TEM) analysis has been possible in the focussed ion beam scanning electron microscope (FIB-SEM) for over 20 years via the in situ lift-out method. Lift-out offers a fast and site specific preparation method for TEM analysis, typically in the field of materials science. More recently it has been applied to a low-water content biological sample (Rubino 2012). This work presents the successful lift-out of high-water content lamellae, under cryogenic conditions (cryo-FIB lift-out) and using a nanomanipulator retaining its full range of motion, which are advances on the work previously done by Rubino (2012). Strategies are explored for maintaining cryogenic conditions, grid attachment using cryo-condensation of water and protection of the lamella when transferring to the TEM.

We report on the growth and formation of single-layer boron nitride dome-shaped nanostructures mediated by small iron clusters located on flakes of hexagonal boron nitride. The nanostructures were synthesized in situ at high temperature inside a transmission electron microscope while the e-beam was blanked. The formation process, typically originating at defective step-edges on the boron nitride support, was investigated using a combination of transmission electron microscopy, electron energy loss spectroscopy and computational modelling. Computational modelling showed that the domes exhibit a nanotube-like structure with flat circular caps and that their stability was comparable to that of a single boron nitride layer.

International audience; We investigated a range of different mesoporous NiO electrodes prepared by different research groups and private firms in Europe to determine the parameters which influence good quality photoelectrochemical devices. This benchmarking study aims to solve some of the discrepancies in the literature regarding the performance of p-DSCs due to differences in the quality of the device fabrication. The information obtained will lay the foundation for future photocatalytic systems based on sensitized NiO so that new dyes and catalysts can be tested with a standardized material. The textural and electrochemical properties of the semiconducting material are key to the performance of photocathodes. We found that both commercial and non-commercial NiO gave promising solar cell and water-splitting devices. The NiO samples which had the two highest solar cell efficiency (0.145% and 0.089%) also gave the best overall theoretical H2 conversion.

In situ-generated, glucose-derived palladium(0) nanoparticles were shown to be convenient and effective catalysts for aqueous Mizoroki–Heck, Sonogashira and Suzuki–Miyaura cross-coupling reactions. The addition of only 4–10 mol% glucose to the reaction mixture lead to a significant increase in yield of the desired products in comparison to processes that omitted the renewable sugar. Interestingly, the Mizoroki–Heck reaction was observed to proceed in good yield even as the reaction reached acidic pH levels. Extensive analysis of the size and morphology of the in situ-formed palladium nanoparticles using advanced analytical techniques showed that the zero valent metal was surrounded by hydrophilic hydroxyl groups. The increased aqueous phase affinity afforded by these groups allowed for facile recycling of the catalyst.

Geometrically complex micro-tools are manufactured via processes which can affect their cutting performances. This paper studies the effects pulsed-laser-ablation and electro-discharge-grinding on polycrystalline diamond matrices and their binder phases at nanometric scales, revealing distinct differences in the resulting substructures. The dissimilarities in micro-scale material removal phenomena of these manufacturing processes combined with their effects on the generated surface topographies and cutting-edge geometries can significantly influence the wear and cutting performance of micro-drills. A study on the micro-drilling of a ceramic matrix composite workpiece material confirms that pulsed-laser-ablation of composite diamond structures offers a step-change in the fabrication of micro-tools.

Cubic boron nitride, being only second to diamond for its hardness and possessing superior thermal stability is suitable for a wide range of applications. In particular, the versatility of this material and its polycrystalline cubic boron nitride composite form can be extended by micro processing enabling its use in advanced manufacturing applications. By employing a pulsed laser ablation technique for the micro texturing of this material, this paper presents for the first time the thermal response of polycrystalline cubic boron nitride incorporating a ceramic binder to the laser ablation process. Combined FIB/TEM/EELS/EDX techniques have been used to characterise a cubic boron nitride based material and its Titanium Carbide binder at nanometric resolutions after the surface has been ablated via an Nd Yag laser. Allotropic transformations of the cubic boron nitride into amorphous boron nitride immediately below the ablated surface and into hexagonal boron nitride down to depths exceeding 300 nm have been identified in a site exposed to high thermal excitation while the boundaries between boron nitride and the primary binder constituents remained definitive. Importantly, the structural integrity of the studied PCBN remained intact below the regions of phase transformations.

In this work, an investigation of soot-in-oil samples drawn from the oil sump of a gasoline direct injection (GDI) engine was carried out. Soot particulate was characterised in terms of size, distribution and shape of the agglomerates, and internal structure of the primary particles. The test engine was a 1.6l modern light-duty EURO IV engine operated at speed between 1600 and 3700rev/min, and torque between 30 and 120Nm. After a double oil-flushing procedure the engine was operated for 30h. Oil samples were drawn from the sump and prepared for Transmission Electron Microscopy (TEM) and High resolution TEM analysis (HRTEM) by a combination of solvent extraction, centrifugation and diethyl ether bathing. Soot agglomerates were measured in terms of their skeleton length and width, and fractal dimension. The mean skeleton length and width were 153nm and 59nm respectively. The fractal dimension was calculated using an iterative method and the mean value was found to be 1.44. The primary particles were found to be spherical in shape with some irregularities and presented an average diameter of 36nm with a mode of 32nm and standard deviation of 13nm. The majority of particles showed an inner core and outer shell similar to diesel soot, although an amorphous layer was also clearly visible.

© 2015 Published by Elsevier B.V. Catheter-associated urinary tract infection (CAUTI) is the commonest hospital-acquired infection, accounting for over 100,000 hospital admissions within the USA annually. Biomaterials and processes intended to reduce the risk of bacterial colonization of the catheters for long-term users have not been successful, mainly because of the need for long duration of activity in flow conditions. Here we report the results of impregnation of urinary catheters with a combination of rifampicin, sparfloxacin and triclosan. In flow experiments, the antimicrobial catheters were able to prevent colonization by common uropathogens Proteus mirabilis, Staphylococcus aureus and Escherichia coli for 7 to 12 weeks in vitro compared with 1-3 days for other, commercially available antimicrobial catheters currently used clinically. Resistance development was minimized by careful choice of antimicrobial combinations. Drug release profiles and distribution in the polymer, and surface analysis were also carried out and the process had no deleterious effect on the mechanical performance of the catheter or its balloon. The antimicrobial catheter therefore offers for the first time a means of reducing infection and its complications in long-term urinary catheter users.

The fabrication of complex three-dimensional gold-containing nanocomposite structures by simultaneous two-photon polymerisation and photoreduction is demonstrated. Increased salt delivers reduced feature sizes down to line widths as small as 78 nm, a level of structural intricacy that represents a significant advance in fabrication complexity. The development of a general methodology to efficiently mix pentaerythritol triacrylate (PETA) with gold chloride hydrate (HAuCl4∙3H2O) is reported, where the gold salt concentration is adjustable on demand from zero to 20 wt%. For the first-time 7-Diethylamino-3-thenoylcoumarin (DETC) is used as the photoinitiator. Only 0.5 wt% of DETC was required to promote both polymerisation and photoreduction of up to 20 wt% of gold salt. This efficiency is the highest reported for Au-containing composite fabrication by two-photon lithography. Transmission Electron Microscopy (TEM) analysis confirmed the presence of small metallic nanoparticles (5.4 ± 1.4 nm for long axis / 3.7 ± 0.9 nm for short axis) embedded within the polymer matrix, whilst X-ray Photoelectron Spectroscopy (XPS) confirmed that they exist in the zero valent oxidation state. UV-vis spectroscopy defined that they exhibit the property of localised surface plasmon resonance (LSPR). The capability demonstrated in this study opens up new avenues for a range of applications, including plasmonics, metamaterials, flexible electronics and biosensors.

© 2014 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Room temperature electroluminescence from semiconductor junctions is demonstrated. The junctions are fabricated by the exfoliation and direct mechanical adhesion of InSe and GaSe van der Waals layered crystals. Homojunction diodes formed from layers of p- and n-type InSe exhibit electroluminescence at energies close to the bandgap energy of InSe (Eg = 1.26 eV). In contrast, heterojunction diodes formed by combining layers of p-type GaSe and n-type InSe emit photons at lower energies, which is attributed to the generation of spatially indirect excitons and a staggered valence band lineup for the holes at the GaSe/InSe interface. These results demonstrate the technological potential of mechanically formed heterojunctions and homojunctions of direct-bandgap layered GaSe and InSe compounds with an optical response over an extended wavelength range, from the near-infrared to the visible spectrum. Room temperature electroluminescence from van der Waals layered semiconductor junctions is demonstrated. The junctions are fabricated by exfoliation and direct mechanical adhesion. These heterostructures are based on direct-bandgap III-VI layered crystals and have atomically flat interfaces, a well-defined band lineup, and a broad optical response from the near-infrared to the visible spectral range.

Laser ablation of diamond composites is of high interest for a wide range of industries for making high wear resistant tools/components. In this context, the paper studies the effects of pulsed laser ablation on a polycrystalline diamond composite (CMX850, average grain size 2 μm, Cobalt binder volume, circa 15%) by identifying the residual carbonic allotropes and metallic binder traces in the ablation region. For this study, grooves were first laser (DMG LASERTEC 60 HSC Q-switched Nd:YAG, pulse duration 20 μs, frequency 10 kHz) ablated into the surface of the polycrystalline diamond structure, then, by using Focused Ion Beam (FIB) techniques, a thin section across the groove was extracted, which allowed the identification of the distinct microstructural characteristics below the ablated surfaces at sites that experienced high and low laser fluence. Using Transmission Electron Microscopy (TEM) imaging and Electron Energy Loss Spectroscopy (EELS) scans, the extracted lamella revealed that amorphous carbon and graphitic structures were formed as a consequence of the ablation process and an abrupt interface graphite to polycrystalline diamond was evident showing an undisturbed polycrystalline diamond (PCD) composite substructure below the graphitic boundary. Furthermore partially evacuated pockets containing traces of the Cobalt binder were identified within the amorphic/graphitic regions of the lamella. The examination of local high and low laser fluence ablated sites has revealed that the extent of residual deposits (amorphic and graphitic carbon) is related to the level of fluence/thermal activity during ablation.

Nanoparticle Tracking Analysis (NTA) has been applied to characterising soot agglomerates of particles and compared with Transmission Electron Microscoscopy (TEM). Soot nanoparticles were extracted from used oil drawn from the sump of a light duty automotive diesel engine. The samples were prepared for analysis by diluting with heptane. Individual tracking of soot agglomerates allows for size distribution analysis. The size of soot was compared with length measurements of projected two-dimensional TEM images of agglomerates. Both the techniques show that soot-in-oil exists as agglomerates with average size of 120nm. NTA is able to measure particles in polydisperse solutions and reports the size and volume distribution of soot-in-oil aggregates; it has the advantages of being fast and relatively low cost if compared with TEM.

Gallium (Ga) helps solubilize rare-earth ions in chalcogenide glasses, but has been found to form the dominant crystallizing selenide phase in bulk glass in our previous work. Here, the crystallization behavior is compared of as-annealed 0–3000 ppmw Dy3+-doped Ge–As–Ga–Se glasses with different Ga levels: Ge16.5As(19−x)GaxSe64.5 (at.%), for x = 3 and 10, named Ga3 and Ga10 glass series, respectively. X-ray diffraction and high-resolution transmission electron microscopy are employed to examine crystals in the bulk of the as-prepared glasses, and the crystalline phase is proved to be the same: Ge-modified, face centered cubic α-Ga2Se3. Light scattering of polished glass samples is monitored using Fourier transform spectroscopy. When Ga is decreased from 10 to 3 at.%, the bulk crystallization is dramatically reduced and the optical scattering loss decreases. Surface defects, with a rough topology observed for both series of as-prepared chalcogenide glasses, are demonstrated to comprise Dy, Si, and [O]. For the first time, evidence for the proposed nucleation agent Dy2O3 is found inside the bulk of as-prepared glass. This is an important result because rare-earth ions bound in a high phonon–energy oxide local environment are, as a consequence, inactive mid-infrared fluorophores because they undergo preferential nonradiative decay of excited states.

A series of ten Co–W coatings have been electrodeposited from the same gluconate bath. The W content of the samples is found to decrease from 22.7 at.% in the first sample to 11.0 at.% in the final sample as the consequent W content of the bath is reduced. The third coating in the series with 18.0 at.% W has been investigated by SEM, TEM and XRD and microhardness testing. This is shown to have a unique, well-ordered, self-organised two-phase nanostructure of platelets parallel to the growth direction separated by a relatively thick grain boundary phase. The platelets have a very well-defined width of 4–5 nm and the interfacial phase is roughly 1 nm thick. The Gibbs free energy for a solid-solution of W in HCP Co is shown to possess spinodal chemistry between the ranges of 8 and 23 at.% W. All the coatings deposited have compositions within this range and this is proposed as a possible mechanism for the origin of the nano-platelet formation. This provides a very well-defined length scale for the lamellar nanostructure. It is shown that the resulting nanostructure is not in compositional equilibrium, but that a final equilibrium state for the self-organised nanocrystalline structure does exist and can be achieved through further W segregation, propagated by annealing at 600 °C. The hardness of the coating is found to increase with the nominal W content, and this is predicted to arise from solid-solution strengthening of the platelets rather than an increase in the area of dislocation-pinning grain boundaries. The uniformity of the underlying nanostructure is expected to significantly enhance the mechanical properties of the coating.

Effective and convenient protocols using renewable sugar-derived palladium(0) nanoparticles (PdNPs) as in situ-formed catalysts for Suzuki–Miyaura cross-coupling reactions in isopropanol under thermal and microwave heating conditions have been developed. The addition of a small amount of glucose (5 mol %) to the reaction mixture lead to an increase in yield of the cross-coupled products compared to control experiments that omitted glucose. The size and morphology of the in situ-formed PdNPs were determined by TEM, and further EF-TEM analysis showed a hydrophilic hydroxylated shell around the individual palladium particles. The polar/hydrophilic nature of the nanoparticles allowed for their facile removal from the cross-coupled product, and a significant decrease in the amount of palladium incorporated into the final product was observed, as measured by ICP-MS analysis.