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A novel material, designated Ru/ZrO2@C(MIL), was prepared by thermal transformation of metal organic framework (MOF), MIL-140C-10, in which 10 % of the conventional biphenyl-dicarboxylate linkers had been substituted with bipyridyl-dicarboxylate linkers, thereby providing sites for Ru coordination with the framework. This MOF precursor was compositionally and morphologically transformed when heated, at 500 °C, in a mixture of H2 and CO2 (3:1). The transformation afforded a high surface area product (114 m2/g) with exceptional stability and high Ru metal dispersion which was very effective as catalyst for the hydrogenation of CO2 to CH4, giving a CH4 production of 53 mol/g Ru/h (at 350 °C, 40 bar and WHSV 344 L/h/g cat.). TEM results show that the active form of the catalyst was a partially degraded (‘unzipped’) MOF structure where Ru° and ZrO2 nanoparticles (2−5 and 10−20 nm diameter, respectively) were dispersed upon carbonaceous ribbons.

Summary Transition metal-based nanomaterials represent an emerging class of highly active and low-cost precatalysts for the oxygen evolution reaction (OER) in alkaline electrolyzers. However, most OER precatalysts undergo slow or incomplete self-reconstructions to generate real active sites, which is a time-consuming process for achieving high OER performance. Thus, we report a new class of OER precatalysts that can achieve highly active OER species by a rapid and deep self-reconstruction (denoted by SELF-RECON). The precatalysts with a core-shell structure comprising NiMoO4 (core) and NiFe/NiFeOx nanoparticles in N-doped amorphous carbons (shell) (denoted by NiMoFeO@NC), can realize rapid MoO42− dissolution and fast formation of NiOOH with Fe incorporation simultaneously. In situ Raman spectroscopy together with electron microscopy, X-ray photoelectron spectroscopy, and electrochemical tests indicate that the obtained NiFeOOH/NiFe-LDH after SELF-RECON behave as the real active species that outperform NiMoFeO@NC, with ultralow overpotentials and extraordinary long-term stability.

It is widely acknowledged that the integrity of the fiber-to-matrix interface inherent to carbon fiber reinforced composites has scope for improvement. One promising and highly-researched strategy is the use of surface manipulation of carbon fibers to enhance their mechanical performance under shear. The complexity of commonly used surface treatments, such as plasma and oxidative etching, Requires modification of existing manufacturing infrastructure and thus their broad adoption in a manufacturing context has been limited. Herein we show that simply impregnating the carbon fibers with aryl diazonium salts and subjecting them to external stimuli, such as mild heating (100 °C), can induce surface modification which can deliver improvements of up to 150% in interfacial shear strength (IFSS) in epoxy resins. Interrogation of the fiber-to-matrix interface using molecular dynamics simulations suggests that the surface grafted molecules imparts a ‘dragging effect’ though the polymer phase and that the surface concentration of these compounds is critical to enhancing IFSS. This process obviates the practical limitations of current functionalization procedures for carbon fibers and requires infrastructure that is already routinely available on fiber manufacturing lines.

This paper investigates fifteen fiber types against two epoxy resin systems and the effects of altering electrochemical oxidization conditions and sizing deposition ratio on interfacial shear strength (IFSS). Oxidization current was altered between 0, 2, and 3.4 A while sizing deposition ratio was altered between unsized, 1:10, 1:15 and 1:20 parts sizing to water. Desized fibers were also compared against pristine unsized fibers. Results show, a correlation between increasing current and IFSS, however sizing has an optimal ratio for best performance. Improvements through oxidization are attributed to the introduction of oxygenated functional groups on the fiber surface while improvements due to sizing are attributed to the promotion of a chemically active intermediate layer between the fiber and resin. Fiber roughness was seen to play no effect on IFSS. Desized fibers and unsized fibers had similar IFSS results however characterisation shows chemical composition of the fiber surfaces to be very different.

Silicon-based impurities are ubiquitous in natural graphite. However, their role as a contaminant in exfoliated graphene and their influence on devices have been overlooked. Herein atomic resolution microscopy is used to highlight the existence of silicon-based contamination on various solution-processed graphene. We found these impurities are extremely persistent and thus utilising high purity graphite as a precursor is the only route to produce silicon-free graphene. These impurities are found to hamper the effective utilisation of graphene in whereby surface area is of paramount importance. When non-contaminated graphene is used to fabricate supercapacitor microelectrodes, a capacitance value closest to the predicted theoretical capacitance for graphene is obtained. We also demonstrate a versatile humidity sensor made from pure graphene oxide which achieves the highest sensitivity and the lowest limit of detection ever reported. Our findings constitute a vital milestone to achieve commercially viable and high performance graphene-based devices., Silicon-based contaminants are ubiquitous in natural graphite, and they are thus expected to be present in exfoliated graphene. Here, the authors show that such impurities play a non-negligible role in graphene-based devices, and use high-purity parent graphite to boost the performance of graphene sensors and supercapacitor microelectrodes.

International audience; While peak fitting of spectra/data is frequently performed in science, recent reports suggest that the quality of peak fitting in the scientific literature is often inadequate. Here, we describe a new statistical tool for determining the quality of fitting protocols, illustrating this capability with X-ray photoelectron spectroscopy (XPS) data. This tool, box plots of random starting conditions and their results, helps identify local minima in the multidimensional fit space of the fit parameters. Ideally, there should be a single global minimum for a fitting protocol such that different, reasonable starting conditions lead to the same result. To determine whether a fit space contains multiple local minima, a series of reasonable starting conditions is randomly chosen for the fit. If the boxes in the box plot of the peak areas of these multiple fits are narrow, the different possibilities converge to a single global minimum. Conversely, if the boxes are wide, multiple local minima are present. This method is related to the mathematical concept of ‘disproof by contradiction’. Our approach is demonstrated with four- and ten-component fits to a moderately complex C 1s XPS narrow scan. The results from our analysis compare favorably to those of traditional Monte Carlo analyses and uniqueness plots, where box plots are also applied to the Monte Carlo results, and each of these statistical tools performs a different function/probes a fit space/protocol differently.

The real-time dissolution of the single-phase compositionally complex alloy (CCA), Al1.5TiVCr, was studied using an inline inductively coupled plasma method. Compositionally complex alloys (CCAs), a term encompassing high entropy alloys (HEAs) or multi-principal element alloys (MPEAs), are—in general—noted for their inherently high corrosion resistance. In order to gain an insight into the dissolution of Al1.5TiVCr alloy, atomic emission spectroelectrochemistry was utilised in order to measure the ion dissolution of the alloy during anodic polarisation. It was revealed that incongruent dissolution occurred, with preferential dissolution of Al, and essentially no dissolution of Ti, until the point of alloy breakdown. Results were correlated with X-ray photoelectron spectroscopy, which revealed a complex surface oxide inclusive of unoxidised metal, and metal oxides in disproportion to the bulk alloying element ratio.

As a group of subject-matter experts in X-ray photoelectron spectroscopy (XPS) and other material characterization techniques from different countries and institutions, we write this document to raise awareness of an epidemic of poor and incorrect materials data analysis in the literature. This issue is a growing problem with many causes and very undesirable consequences. It contributes to what has been called a "reproducibility crisis", which is a recent concern of the U.S. National Academies of Science (Baker,2016; Harris, 2017; NASE&M, 2019).

Summary Effective design of bifunctional catalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is important but remains challenging. Herein, we report a three-dimensional (3D) hierarchical structure composed of homogeneously distributed Ni-Fe-P nanoparticles embedded in N-doped carbons on nickel foams (denoted as Ni-Fe-P@NC/NF) as an excellent bifunctional catalyst. This catalyst was fabricated by an anion exchange method and a low-temperature phosphidation of nanotubular Prussian blue analogue (PBA). The Ni-Fe-P@NC/NF displayed exceptional catalytic activity toward both HER and OER and delivered an ultralow cell voltage of 1.47 V to obtain 10 mA cm−2 with extremely excellent durability for 100 h when assembled as a practical electrolyser. The extraordinary performance of Ni-Fe-P@NC/NF is attributed to the abundance of unsaturated active sites, the well-defined hierarchical porous structure, and the synergistic effect between multiple components. Our work will inspire more rational designs of highly active non-noble electrocatalysts for industrial energy applications., Graphical Abstract, Highlights • Nanotubular Prussian blue analogue as a precursor is synthesized by anion exchange • The catalyst exhibits excellent catalytic activity for hydrogen and oxygen production • The catalyst-based electrolyser has a low cell voltage of 1.47 V to obtain 10 mA cm−2 • The electrolyser shows an extremely excellent durability for 100 h at 50 mA cm−2, Catalysis; Materials Chemistry; Nanomaterials; Energy Materials

Efficient storage of solar and wind power is one of the most challenging tasks still limiting the utilization of the prime but intermittent renewable energy sources. The direct storage of concentrated solar power in renewable fuels via thermochemical splitting of water and carbon dioxide on a redox material is a scalable approach with up to 54% solar-to-fuel conversion efficiency. Despite progress, the search for earth-abundant materials that can provide and maintain high H2 and CO production rates over long period of high-temperature cycles continues. Here, we report a strategy to unlock the use of manganese, the 12th most abundant element in the Earth's crust, for thermochemical synthesis of solar fuels, achieving superior thermochemical stability, oxygen exchange capacity, and up to seven times higher mass-specific H2 and CO yield than cerium dioxide. We observe that incorporation of a small fraction of cerium ions in the manganese (II,III) oxide crystal lattice drastically increases its oxygen ion mobility, allowing its reduction from oxide to carbide during methane partial oxidation with simultaneous Ce exsolution. High CO2 and H2O splitting rates are achieved by re-oxidation of the carbide to manganese (II) oxide with simultaneous reincorporation of the cerium ions. We demonstrate that the oxide to carbide reaction is highly reversible achieving remarkable CO2 splitting rates over 100 thermochemical cycles of methane partial oxidation and CO2 splitting, and preserving the initial oxygen exchange capacity of 0.65 molO m o l M n − 1 and 89% of the fuel production rates. Due to this extraordinarily high reversible oxygen exchange capacity, the 3% Ce-doped manganese oxide achieves an average mass-specific CO yield for CO2 splitting of 17.72 mmolCO g−1, which is significantly higher than that previously achieved in thermochemical redox cycles. More generally, these findings suggest that incorporation of small soluble amounts of cerium in earth-abundant transition metal oxides like manganese oxide is a powerful approach to enable solar thermochemical fuel synthesis.

International audience; Colored and color-changing materials are central to perception and interaction in nature and have been exploited in an array of modern technologies such as sensors, visual displays and smart materials. Attempts to introduce color into carbon fiber materials have been limited by deleterious impacts on fiber properties, and the extension of colored fibers towards 'smart composites' remains in its infancy. We present carbon fibers incorporating structural color, similar to that observed on the surface of soap bubbles and various insects and birds, by modifying the fiber surface through in situ polymerization grafting. When dry, the treated fibers exhibit a striking blue color, but when exposed to a volatile solvent, a cascade of colors across the visible region is observed as the film first swells and then shrinks as the solvent evaporates. The treated fibers not only possess a unique color and color-changing ability, but can also be reversibly formed into complex shapes and bear significant loads even without being encased in a supporting polymer. The tensile strength of treated fibers shows a statistically significant increase (+12%) and evaluation of the fiber-to-matrix adhesion of these polymers to an epoxy resin shows more than 300% improvement over control fibers. This approach creates a new platform for the multifaceted advance of smart composites.

Metal halide perovskite solar cells (PSC) exhibit outstanding power conversion efficiencies when fabricated as mm-sized devices, but creation of high-performing large-area PSCs that are stable under operating conditions on a sufficiently long timescale still presents a significant challenge. We demonstrate herein that modification of the interface between the perovskite and a spiro-OMeTAD hole-transporting material with commercially available para-substituted benzenethiol molecules facilitates fabrication of cm-sized PSCs with both improved efficiency and stability. Comprehensive analysis using specialised and conventional physical characterisation techniques has been undertaken to demonstrate that band alignment at the perovskite surface can be tuned to improve the solar cell efficiency via adsorption of benzenethiols with a significant dipole moment. Moreover, modification of the perovskite with cyano-substituted benzenethiol enhances charge extraction and reduces charge recombination in the devices. These effects enable improvements in the power conversion efficiency of PSCs from 19.0 to 20.2% and from 18.5 to 19.6% under 1 sun AM 1.5G irradiation with 0.16 and 1.00 cm2 apertures, respectively. Most importantly, benzenethiol-modified perovskite solar cells retain more than 80% of the initial performance after 185 h of continuous operation at 50% relative humidity and 50 °C device temperature under 1 sun irradiation, while devices with no interfacial modification undergo continuous deterioration down to 35% of the initial efficiency. These significant improvements are provided by a very simple and highly reproducibile modification procedure that can be readily adopted in other types of PSCs.

Hydrogen at present is mainly produced from fossil fuels for use in ammonia synthesis, the petrochemical industry, and chemical production. In the future, hydrogen will be increasingly used as an energy vector. Although water electrolysis to produce hydrogen with renewable electricity offers a clean process, the approach is energy intensive, requiring a large renewable resource footprint. Methanol-water co-electrolysis can reduce the energy input by > 50%; its electrochemical oxidation poses complex issues such as poisoning of the catalyst, sluggish oxidation kinetics, and degradation over time. The addition of nano-sized SnO2 to PtRu/C catalyst, to reduce noble metal loading, has been shown here to reduce catalyst leaching and increase the chemical, micro-structural, and performance stability of the methanol-water co-electrolysis process during extended periods of testing. The electrochemical characterization, analysis of the methanol solution, and exit gases, post-cell testing, revealed complete oxidation of methanol with little performance degradation. This is further supported by the stability of the catalyst composition and structure as revealed by the post-mortem XRD and XPS analysis of the cell. The energy balance calculations show that methanol-water co-electrolysis can significantly reduce the renewable energy footprint, and the process can become carbon neutral if bio-methanol is used with renewable electricity.

Coupling TiO2 with WO3 to develop photocatalytic heterojunctions is one of the most widely used strategies to realize their superior photoactivity. However, the interfacial charge transfer in these heterojunctions is not efficient to achieve an optimized activity. For the first time, the present study reports a facile hydrolysis-hydrothermal approach, whereby ultradispersed TiO2 nanocrystals and WO3 nanorods are concurrently anchored onto reduced graphene oxide (rGO) and formed a novel Z-scheme heterojunction photocatalyst TiO2/rGO/WO3 (TRW). Transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence spectra (PL) are employed to characterize TRW. Control experiments indicate that, in the synthesis process, glucose and the by-product sodium chloride from the hydrolysis reactions are critical for forming highly dispersed and uniform-sized TiO2 nanocrystals and WO3 nanorods. Compared with TiO2/WO3 nanocomposites, TRW shows enhanced activity for bacterial inactivation under simulated solar light. As confirmed by electrochemical characterizations and the reactive oxygen species, rGO in TRW suppresses the recombination of electron-hole pairs and boosts the O2 reduction reactions during photocatalytic process. Z-scheme electron transfer in TRW is proposed based on surface redox reactions and XPS analysis after light irradiation. This study could provide a new clue for designing graphene-based heterojunction photocatalysts for environmental applications.

Influence of the conditions for aerobic oxidation of Mn2+(aq) catalysed by the MnxEFG protein complex on the morphology, structure and reactivity of the resulting biogenic manganese oxides (MnOx ) is explored. Physical characterisation of MnOx includes scanning and transmission electron microscopy, and X-ray photoelectron and K-edge Mn, Fe X-ray absorption spectroscopy. This characterisation reveals that the MnOx materials share the structural features of birnessite, yet differ in the degree of structural disorder. Importantly, these biogenic products exhibit strikingly different morphologies that can be easily controlled. Changing the substrate-to-protein ratio produces MnOx either as nm-thin sheets, or rods with diameters below 20 nm, or a combination of the two. Mineralisation in solutions that contain Fe2+(aq) makes solids with significant disorder in the structure, while the presence of Ca2+(aq) facilitates formation of more ordered materials. The (photo)oxidation and (photo)electrocatalytic capacity of the MnOx minerals is examined and correlated with their structural properties.

Thiol groups can undergo a large variety of chemical reactions and are used in solution phase to conjugate many bioactive molecules. Previous research on solid substrates with continuous phase glow discharge polymerization of thiol-containing monomers may have been compromised by oxidation. Thiol surface functionalization via glow discharge polymerization has been reported as requiring pulsing. Herein, continuous phase glow discharge polymerization of allyl mercaptan (2-propene-1-thiol) was used to generate significant densities of thiol groups on a mixed macrodiol polyurethane and tantalum. Three general classes of chemistry are used to conjugate proteins to thiol groups, with maleimide linkers being used most commonly. Here the pH specificity of maleimide reactions was used effectively to conjugate surface-bound thiol groups to amine groups in collagen. XPS demonstrated surface-bound thiol groups without evidence of oxidation, along with the subsequent presence of maleimide and collagen. Glow discharge reactor parameters were optimized by testing the resistance of bound collagen to degradation by 8 M urea. The nature of the chemical bonding of collagen to surface thiol groups was effectively assessed by colorimetric assay (ELISA) of residual collagen after incubation in 8 M urea over 8 days and after incubation with keratinocytes over 15 days. The facile creation of useable solid-supported thiol groups via continuous phase glow discharge polymerization of allyl mercaptan opens a route for attaching a vast array of bioactive molecules. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1940-1948, 2017.

We have found demonstrated that the use of tetrahydrofuran (THF) as a solvent to produce dispersed, water soluble fullerenes results in significant oxidation and degradation of the fullerene cage, which has not been reported previously. We also report a new finding that the use of N, N-dimethylformamide (DMF) can also generate stabilised fullerene (C60) nanoparticle dispersions in aqueous solutions including water and phosphate buffered saline (PBS) buffer. We compare this new DMF method with the well-known THF method following an extensive chemical and physical analysis of the resulting nanoparticles. The exact mechanism of action behind this oxidation and degradation is unknown, however, the role of peroxides is likely. The method of solvent exchange based on the use of DMF results in the formation of fullerene nanoparticle agglomerates that are highly stable in PBS and water, while the THF agglomerates are only stable in water. However, caution should be applied when using these approaches due to the significant degradation of the fullerene cage observed when using various techniques such as dynamic light scattering (DLS), matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR) and cryo transmission electron microscopy (cryo-TEM). Our results show that the solvent exchange technique using THF results in partial oxidation and degradation of C60, interestingly, the DMF evaporative method results in greater oxidation and degradation of C60 but significantly enhanced colloidal stability in buffer.

Reproducible and in-depth studies of the electrochemical graphite intercalation and oxidation processes were carried out with the use of an electrochemical Tee-cell setup. The electrochemical method allowed simpler and greater controllability over the level of oxidation/functionalization, relative to the commonly employed chemical oxidation approach (e.g. the modified Hummers method). Extensive characterization was carried out to understand the properties of the electrochemically-derived graphite oxide (EGrO), and it was found that the abundance of each functionality was highly dependent on the electrochemical reaction time or the concentration of the electrolyte (perchloric acid) employed. Notably, the amount of oxygen functional groups on EGrO could be as high as 30 wt%, but the degree of oxidation did not proceed beyond the generation of carbonyl species. The controllable oxidation level of the EGrO makes it an attractive precursor for many applications, such as electronics and nanocomposites.

The electrochemical performance of porous silicon (pSi) stabilized via thermal decomposition of acetylene gas is investigated for the first time. In this study, pSi undergoes two thermal treatments at either 525 or 800 °C, which result in hydrogen-terminated thermally hydrocarbonized pSi (THCpSi) and hydroxyl-terminated thermally carbonized pSi (TCpSi), respectively, the latter upon dipping in hydrofluoric acid to activate the surface termination. Electrochemical characterization, using cyclic voltammetry, chronocoulometry, and electrochemical impedance spectroscopy in the presence of several redox pairs, [Fe(CN) 6 ] 3/4− , [Ru(NH 3 ) 6 ] 2/3+ , and hydroquinone/quinone, is used to demonstrate the versatility and high stability to degradation of carbon-stabilized pSi nanostructures and their excellent electrochemical performance. Added to the large surface area, adjustable pore morphology and tailorable surface chemistry of THCpSi and TCpSi, these nanostructures demonstrate fast electron-transfer kinetics, providing key advantages over conventional carbon electrodes. The versatile surface chemistry of THCpSi and TCpSi offer various possibilities to introduce multiple functional groups depending on the nature of the bioreceptor to be immobilized. For proof of principle, the use of a THCpSi-based immunosensor to detect MS2 bacteriophage is demonstrated by means of electrochemical impedance spectroscopy, showing a detection limit of 4.9 pfu mL −1 . Carbon-stabilized pSi structures represent a new class of nanostructured electrodes for biosensing applications Refereed/Peer-reviewed

The carbon 1s photoelectron spectrum is the most widely fit and analyzed narrow scan in the x-ray photoelectron spectroscopy (XPS) literature. It is, therefore, critically important to adopt well-established protocols based on best practices for its analysis, since results of these efforts affect research outcomes in a wide range of different application areas across materials science. Unfortunately, much XPS peak fitting in the scientific literature is inaccurate. In this guide, we describe and explain the most common problems associated with C 1s narrow scan analysis in the XPS literature. We then provide an overview of rules, principles, and considerations that, taken together, should guide the approach to the analysis of C 1s spectra. We propose that following this approach should result in (1) the avoidance of common problems and (2) the extraction of reliable, reproducible, and meaningful information from experimental data.

The polymerisation and attachment of a covalent sizing to the surface of carbon fibres is demonstrated using an electrochemical surface treatment. This treatment proceeds in an aqueous environment at a constant potential of −1 V in 2 min, and thus is within the window of current industrial surface treatments (2–4 min). This treatment demonstrates the ability to significantly increase the tensile strength (up to 25%), Young’s modulus (up to 15%) and interfacial shear strength (IFSS, up to 199%) in an epoxy resin. Optimisation of this process gave similar improvements in carbon fibre properties and IFSS at lower monomer concentrations (0.2 M and 0.5 M vs 1.0 M). This treatment is demonstrated on both bundles of fibres and woven fabrics and the woven fabrics are able to be reversibly moulded into different shapes by simply wetting the surface with an appropriate solvent and allowing to dry.

This study was undertaken to understand the extent and nature of problems in x-ray photoelectron spectroscopy (XPS) data reported in the literature. It first presents an assessment of the XPS data in three high-quality journals over a six-month period. This analysis of 409 publications showing XPS spectra provides insight into how XPS is being used, identifies the common mistakes or errors in XPS analysis, and reveals which elements are most commonly analyzed. More than 65% of the 409 papers showed fitting of XP spectra. An ad hoc group (herein identified as "the committee") of experienced XPS analysts reviewed these spectra and found that peak fitting was a common source of significant errors. The papers were ranked based on the perceived seriousness of the errors, which ranged from minor to major. Major errors, which, in the opinion of the ad hoc committee, can render the interpretation of the data meaningless, occurred when fitting protocols ignored underlying physics and chemistry or contained major errors in the analysis. Consistent with other materials analysis data, ca. 30% of the XPS data or analysis was identified as having major errors. Out of the publications with fitted spectra, ca. 40% had major errors. The most common elements analyzed by XPS in the papers sampled and researched at an online database, include carbon, oxygen, nitrogen, sulfur, and titanium. A scrutiny of the papers showing carbon and oxygen XPS spectra revealed the classes of materials being studied and the extent of problems in these analyses. As might be expected, C 1s and O 1s analyses are most often performed on sp2-type materials and inorganic oxides, respectively. These findings have helped focus a series of XPS guides and tutorials that deal with common analysis issues. The extent of problematic data is larger than the authors had expected. Quantification of the problem, examination of some of the common problem areas, and the development of targeted guides and tutorials may provide both the motivation and resources that enable the community to improve the overall quality and reliability of XPS analysis reported in the literature Refereed/Peer-reviewed

The objective of the study was to determine optimum inlet and outlet air temperatures of spray process for producing co-microcapsules containing omega-3 rich tuna oil and probiotic bacteria L. casei. These co-microcapsules were produced using whey protein isolate and gum Arabic complex coacervates as shell materials. Improved bacterial viability and oxidative stability of omega-3 oil were used as two main criteria of this study. Three sets of inlet (130°C, 150°C, and 170°C) and outlet (55°C, 65°C, and 75°C) air temperatures were used in nine combinations to produce powdered co-microcapsule. The viability of L. casei, oxidative stability of omega-3 oil, surface oil, oil microencapsulation efficiency, moisture content, surface elemental composition and morphology of the powdered samples were measured. There is no statistical difference in oxidative stability at two lower inlet air temperatures (130°C and 150°C). However, there was a significant decrease in oxidative stability when higher inlet tempe...

The modification of carbon fibre surfaces has been achieved using a novel combination of low power microwave irradiation (20 W) in both an ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and an organic solvent (1,2-dichlorobenzene). The use of the ionic liquid was superior to the organic solvent in this application, resulting in a higher density of surface grafted material. As a consequence, carbon fibres treated in the ionic liquid displayed improved interfacial adhesion in the composite material (+28% relative to untreated fibres) compared to those treated in organic solvent (+18%). The methodology presented herein can be easily scaled up to industrially relevant quantities and represent a drastic reduction in both reaction time (30 min from 24 h) and energy consumption, compared to previously reported procedures. This work opens the door to potential energy and time saving strategies which can be applied to carbon fibre manufacture for high performance carbon fibre reinforced composites.

The use of light-weight magnesium (Mg) alloys as engineering materials has been hampered in part due to their poor corrosion performance. This work aims to address the corrosion issue of Mg by introducing a functional protective coating system consisting of an intermediate active metallic film (anodic with respect to Mg) and an outer passive coating to slow the rate of dissolution of the intermediate active metallic film; which is akin to the protective surface coating system utilised for galvanised steel. If the outer passive coating is damaged or loses its integrity, the active (i.e. anodic) coating is expected to electrochemically sacrifice itself to impose protection upon the underlying Mg substrate. This work represents a novel corrosion protection system for Mg, and is demonstrated herein for a lanthanum based coating system upon commercial Mg-alloy AZ91D.

Omega-3 fatty acids and probiotic bacteria were co-encapsulated in a single whey protein isolate (WPI)–gum Arabic (GA) complex coacervate microcapsule. Tuna oil (O) and Lactobacillus casei 431 (P) were used as models of omega-3 and probiotic bacteria, respectively. The co-microcapsules (WPI-P-O-GA) and L. casei containing microcapsules (WPI-P-GA) were converted into powder by using spray and freeze drying. The viability of L. casei was significantly higher in WPI-P-O-GA co-microcapsules than in WPI-P-GA. The oxidative stability of tuna oil was significantly higher in spray dried co-capsules than in freeze dried ones.

Colistin is often the only effective antibiotic against the respiratory infections caused by multidrug-resistant Gram-negative bacteria. However, colistin-resistant multidrug-resistant isolates have been increasingly reported and combination therapy is preferred to combat resistance. In this study, five combination formulations containing colistin (COL) and rifampicin (RIF) were prepared by spray drying. The lowest minimum inhibitory concentration (MIC) value against Pseudomonas aeruginosa PAO1 was measured for the formulation of COL/RIF = 4:1 with relatively high emitted doses (over 80%) and satisfactory fine particle fractions (over 60%). Data from X-ray photoelectron spectroscopy (XPS) and nano-time-of-flight secondary ion mass spectrometry (ToF-SIMS) showed the surfaces of particles were mainly covered by rifampicin even for the formulation with a mass ratio of COL/RIF = 4:1. Because colistin is hygroscopic and rifampicin is hydrophobic, moisture absorption of combination formulations was significantly lower than the pure colistin formulation in the dynamic vapour sorption results. To investigate the dissolution characteristics, four dissolution test methods (diffusion Franz cell, modified Franz cell, flow-through and beaker methods) were employed and compared. The modified Franz cell method was selected to test the dissolution behaviour of aerosolised powder formulations to eliminate the effect of membrane on dissolution. The results showed that surface enrichment of hydrophobic rifampicin neither affected aerosolisation nor retarded dissolution rate of colistin in the combination formulations. For the first time, advanced surface characterisation techniques of XPS and ToF-SIMS have shown their capability to understand the effect of surface composition on the aerosolisation and dissolution of combination powders. Refereed/Peer-reviewed

A recently established means of surface functionalization of unsized carbon fibres for enhanced compatibility with epoxy resins was optimised and evaluated using interfacial shear stress measurements. Interfacial adhesion has a strong influence on the bulk mechanical properties of composite materials. In this work we report on the optimisation of our aryl diazo-grafting methodology via a series of reagent concentration studies. The fibres functionalised at each concentration are characterised physically (tensile strength, modulus, coefficient of friction, and via AFM), and chemically (XPS). The interfacial shear strength (IFSS) of all treated fibres was determined via the single fibre fragmentation test, using the Kelly–Tyson model. Large increases in IFSS for all concentrations (28–47%) relative to control fibres were observed. We show that halving the reagent concentration increased the coefficient of friction of the fibre and the interfacial shear strength of the composite while resulting in no loss of the key performance characteristics in the treated fibre.

The tethering of an amphiphilic molecule to the surface of carbon fiber resulted in significant (+283%) improvements in interfacial shear strength. Molecular dynamics simulations revealed that lateral association of hydrophobic sections lead to a ‘hooked’ conformation through which polymer chains become entangled. Further simulations indicated that a small molecule, forced into this conformation via two covalent attachment points to the fiber surface (similar to a ‘horseshoe’), would provide similar adhesion improvements and confirm this conformational effect on interfacial phenomena. This prediction was confirmed by the synthesis and grafting of such a molecule to a carbon fiber surface, giving an almost identical improvement in interfacial adhesion (+276%). This work validates the use of molecular dynamics to inform molecular architectural design and demonstrates the translation of molecular conformation and shape at a composite interface from nano-to macroscale.

This guide deals with methods to control surface charging during XPS analysis of insulating samples and approaches to extracting useful binding energy information. The guide summarizes the causes of surface charging, how to recognize when it occurs, approaches to minimize charge buildup, and methods used to adjust or correct XPS photoelectron binding energies when charge control systems are used. There are multiple ways to control surface charge buildup during XPS measurements, and examples of systems on advanced XPS instruments are described. There is no single, simple, and foolproof way to extract binding energies on insulating material, but advantages and limitations of several approaches are described. Because of the variety of approaches and limitations of each, it is critical for researchers to accurately describe the procedures that have been applied in research reports and publications.

XPS is widely used to identify and quantify the elements present at the surface of polymeric materials. The energy distribution of photoelectrons emitted from these elements contains information about their chemical state, potentially allowing the analyst to identify and quantify specific functional groups. These functional groups may originate from the synthesis and processing of the polymers, from postsynthetic modifications such as surface grafting, or indeed may be unrelated to the polymer (additives and contaminants). Extracting reliable and meaningful information from XPS data is not trivial and relies on careful and appropriate experimentation, including experimental design, sample preparation, data collection, data processing, and data interpretation. Here, the authors outline some of these challenges when performing XPS analysis of polymers and provide practical examples to follow. This guide will cover all relevant aspects over the course of a typical experiment, including tips and considerations when designing the experiment, sample preparation, charge neutralization, x-ray induced sample damage, depth profiling, data analysis and interpretation, and, finally, reporting of results. Many of these topics are more widely applicable to insulating organic materials, and the recommendations of this guide will help to ensure that data is collected and interpreted using current best practices.

Paper and cellulosic films are used in many designs of low-cost diagnostics such as paper-based blood grouping devices. A major issue limiting their commercialization is the short stability of the functional biomolecules. To address this problem, the effect of relative humidity (RH) and bovine serum albumin (BSA) on the antibody bioactivity and the surface chemical composition of a paper blood typing biodiagnostic were studied. An IgM blood typing antibody was physisorbed from solution onto paper - with or without BSA pretreatment, and aged for periods up to 9 weeks at room temperature and under different RH conditions. The blood typing efficiency of the antibodies and the substrate surface chemical composition were analyzed by image analysis and X-ray photoelectron spectroscopy (XPS), respectively. This study tests two hypotheses. The first is that the hydroxyl groups in paper promote antibody denaturation on paper; the second hypothesis is that proteins such as BSA can partially block the hydroxyl groups with paper, thus preserving antibody bioactivity. Results show that high RH is detrimental to antibody longevity on paper, while BSA can block hydroxyl groups and prolong antibody longevity by almost an order of magnitude – regardless of humidity. This study opens up new engineering concepts to develop robust and marketable paper diagnostics. The simplest is to store paper and antibody based diagnostics in moisture proof packages.

This study aimed to assess the robustness of using a spray drying approach and formulation design in producing inhalable phage powders. Two types of Pseudomonas phages, PEV2 (Podovirus) and PEV40 (Myovirus) in two formulations containing different amounts of trehalose (70% and 60%) and leucine (30% and 40%) were studied. Most of the surface of the produced powders was found to be covered in crystalline leucine. The powders were stored at 4 °C and 20 °C under vacuum. The phage stability and in vitro aerosol performance of the phage powders were examined on the day of production and after 1, 3 and 12 months of storage. A minor titer loss during production was observed for both phages (0.2–0.8 log10 pfu/ml). The storage stability of the produced phage powders was found to be phage and formulation dependent. No further reduction in titer occurred for PEV2 powders stored at 4 °C across the study. The formulation containing 30% leucine maintained the viability of PEV2 at 20 °C, while the formulation containing 40% leucine gradually lost titer over time with a storage reduction of ∼0.9 log10 pfu/ml measured after 12 months. In comparison, the PEV40 phage powders generally had a ∼ 0.5 log10 pfu/ml loss upon storage regardless of temperature. When aerosolized, the total in vitro lung doses of PEV2 were of the order of 107 pfu, except the formulation containing 40% leucine stored at 20 °C which had a lower lung dose. The PEV40 powders also had lung doses of 106–107 pfu. The results demonstrate that spray dried Myoviridae and Podoviridae phage in a simple formulation of leucine and trehalose can be successfully stored for one year at 4 °C and 20 °C with vacuum packaging. The University of Sydney; Australian Research Council; National Institute of Allergy and Infectious Diseases of the National Institutes of Health; National Health and Medical Research Council Centre of Research Excellence in Tuberculosis Control

The possibility of efficient water electrooxidation sustained by continuous (re)generation of catalysts derived from the oxidative electrodeposition of transition-metal contaminants is examined herein for three natural water samples from Australia and China. The metal composition of the solutions has been determined by inductively coupled plasma optical emission spectrometry, and a range of strategies to produce water-splitting catalysts by means of in situ electrodeposition have been applied. The performance of the resulting electrocatalysts is below the state-of-the-art level owing to large amounts of impurities in the solutions and non-optimal concentrations of naturally available catalyst precursors. Nevertheless, these studies have identified the FePb-based system as a rare example of an electrocatalyst for water oxidation that forms in situ and maintains reasonable activity (≥4.5 mA cm-2 at an overpotential of 0.8 V) in weakly acidic solutions (pH 2.9).

Complex molecules have been successfully grafted onto the surface of unsized carbon fibre, a heterogeneous material which is a challenge to functionalise. The in situ generation of highly reactive phenyldiazo-species from their corresponding anilines was employed to achieve this task. The success of an initial proof-of-concept study (bearing a nitro moiety) supported by X-ray Photoelectron Spectroscopy (XPS) and physical characterisation, led to the design and synthesis of a more complex compound possessing a pendant amine moiety which could theoretically react with an epoxide based resin. After attachment to unsized oxidised fibres, analysis by XPS of the resulting fibres (fluorine used as an XPS tag) indicated a marked difference in functionalisation success which was attributed to steric factors, shown to be critical in influencing the attachment of the phenyldiazo-intermediate to the carbon fibre surface. Analysis of key fibre performance parameters of these fibres showed no change in elastic modulus, strength, surface topography or microscopic roughness when compared to the control unsized oxidised fibres. The functionalised fibres did however show a large increase in coefficient of friction. Single fibre fragmentation tests indicated a marked increase in interfacial shear strength, which was attributed to the pendent amine functionalities interacting with the epoxy resin.

Development of extremely low density graphene elastomer (GE) holds the potential to enable new properties that traditional cellular materials cannot offer, which are promising for a range of emerging applications, ranging from flexible electronics to multifunctional scaffolds. However, existing graphene foams with extremely low density are generally found to have very poor mechanical resilience. It is scientifically intriguing but remains unresolved whether and how the density limit of this class of cellular materials can be further pushed down while their mechanical resilience is being retained. In this work, a simple annealing strategy is developed to investigate the role of intersheet interactions in the formation of extreme-low-density of graphene-based cellular materials. It is discovered that the density limit of mechanically resilient cellular GEs can be further pushed down as low as 0.16 mg cm-3 through thermal annealing. The resultant extremely low density GEs reveal a range of unprecedented properties, including complete recovery from 98% compression in both of liquid and air, ultrahigh solvent adsorption capacity, ultrahigh pressure sensitivity, and light transmittance.

This study has investigated the surface coating efficiency and powder flow improvement of a model cohesive acetaminophen powder by high-shear processing with pharmaceutical lubricants through 2 common equipment, conical comil and high-shear mixer. Effects of coating materials and processing parameters on powder flow and surface coating coverage were evaluated. Both Carr's index and shear cell data indicated that processing with the lubricants using comil or high-shear mixer substantially improved the flow of the cohesive acetaminophen powder. Flow improvement was most pronounced for those processed with 1% wt/wt magnesium stearate, from "cohesive" for the V-blended sample to "easy flowing" for the optimally coated sample. Qualitative and quantitative characterizations demonstrated a greater degree of surface coverage for high-shear mixing compared with comilling; nevertheless, flow properties of the samples at the corresponding optimized conditions were comparable between 2 techniques. Scanning electron microscopy images demonstrated different coating mechanisms with magnesium stearate or l-leucine (magnesium stearate forms a coating layer and leucine coating increases surface roughness). Furthermore, surface coating with hydrophobic magnesium stearate did not retard the dissolution kinetics of acetaminophen. Future studies are warranted to evaluate tableting behavior of such dry-coated pharmaceutical powders. Refereed/Peer-reviewed

Paper has been used to engineer many types of bio-diagnostics. A major issue to most paper-based bio-diagnostics is the biomolecule instability causing the short shelf-life of the diagnostics. Commercial papers contain various polymeric additives. Polyamidoamine-epichlorohydrin (PAE), a polyelectrolyte typically used as wet-strength agent, is commonly used in filter papers and paper towels, which are often used as substrate in bioactive paper. However, the effect of cellulose or polymeric additives on antibody bioactivity is unknown. This limits paper optimization for diagnostic applications. In this study, model papers were made with and without PAE addition. IgM Anti-A blood typing antibody was physisorbed and dried on paper, aged for up to 9 weeks at different relative humidity (RH) conditions and the antibody activity was measured. The antibody bioactivity was represented as blood typing efficiency measured by image analysis. The surface chemical composition was measured using X-ray photoelectron spectroscopy (XPS). Antibody bioactivity loss was promoted by elevated RH, corresponding to increased paper water content. PAE significantly reduces the paper water content under ambient environment. Antibody bioactivity is higher on paper made with PAE under the high humidity conditions (57.6%-84.3% RH). However, under conditions of humidity saturation (100%RH), PAE shows little effect on reducing paper water content nor on protecting antibody bioactivity. These results demonstrate the water content of paper to be associated with antibody bioactivity loss.

Hypothesis The amount and distribution of slip agents, erucamide, and behenamide, on the surface of high-density polyethene, is determined by integral characteristics of slip agent structure and polymer morphology. A suite of surface analysis techniques was applied to correlate physicochemical properties with slip-additive migration behaviour and their surface morphology. The migration, surface morphology and physicochemical properties of the slip additives, crystallinity and orientation of polyethene spherulites and interaction between slip additives and high-density polyethene influence the surface characteristics. Experimental The high-density polyethene closures were produced with erucamide and behenamide separately and stored until they produced required torque. Surface composition was determined employing spectroscopy and gas chromatography. The distribution of additives was observed under optical, scanning electron and atomic force microscopes. The surface energy, crystallinity and application torque were measured using contact angle, differential scanning calorimeter and a torque force tester respectively. Results and discussion Each slip additive produced a characteristic amide peak at 1645 cm−1 in infrared spectroscopy and peaks of oxygen and nitrogen in X-ray photoelectron spectroscopy, suggesting their presence on the surface. The erucamide produced placoid scale-like structures and behenamide formed denticulate structures. The surface erucamide and behenamide responsible for reducing the torque was found to be 15.7 µg/cm2 and 1.7 µg/cm2.

The performance of composite laminates depends on the adhesion between the fibre reinforcement and matrix, with the surface properties of the fibres playing a key role in determining the level of adhesion achieved. For this reason it is important to develop an in-depth understanding of the surface functionalities on the reinforcement fibres. In this work, multi-scale surface analysis of carbon fibre during the three stages of manufacture; carbonisation, electrolytic oxidation, and epoxy sizing was carried out. The surface topography was examined using scanning electron microscopy (SEM), which revealed longitudinal ridges and striations along the fibre-axis for all fibre types. A small difference in surface roughness was observed by scanning probe microscopy (SPM), while the coefficient of friction measured by an automated single fibre tester showed 51% and 98% increase for the oxidised and sized fibres, respectively. The fibres were found to exhibit heterogeneity in surface energy as evidenced from SPM force measurements. The unsized fibres were much more energetically heterogeneous than the sized fibre. A good correlation was found between fibre properties (both physical and chemical) and interlaminar shear strength (ILSS) of composites made from all three fibre types.

For many respiratory infections caused by multidrug-resistant Gram-negative bacteria, colistin is the only effective antibiotic despite its nephrotoxicity. A novel inhaled combination formulation of colistin with a synergistic antimicrobial component of rifampicin was prepared via co-spray drying, aiming to deliver the drug directly to the respiratory tract and minimize drug resistance and adverse effects. Synergistic antibacterial activity against Acinetobacter baumannii was demonstrated for the combination formulation with high emitted doses (96%) and fine particle fraction total (FPFtotal; 92%). Storage of the spray-dried colistin alone formulation in the elevated relative humidity (RH) of 75% resulted in a substantial deterioration in the aerosolization performance because the amorphous colistin powders absorbed significant amount of water up to 30% by weight. In contrast, the FPFtotal values of the combination formulation stored at various RH were unchanged, which was similar to the aerosolization behavior of the spray-dried rifampicin-alone formulation. Advanced surface chemistry measurements by XPS and ToF-SIMS demonstrated a dominance of rifampicin on the combination particle surfaces, which contributed to the moisture protection at the elevated RH. This study shows a novel inhalable powder formulation of antibiotic combination with the combined beneficial properties of synergistic antibacterial activity, high aerosolization efficiency, and moisture protection.