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Phase recognition in SEM-EDX chemical maps using positive matrix factorization
Get PDFImages from scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) are informative and useful to understand the chemical composition and mixing state of solid materials. Positive matrix factorization (PMF) is a multivariate factor analysis technique that has been used in many applications, and the method is here applied to identify factors that can describe common features between elemental SEM-EDX maps. The procedures of converting both graphics and digital images to PMF input files are introduced, and the PMF analysis is exemplified with an open-access PMF program. A case study of oxygen carrier materials from oxygen carrier aided combustion is presented, and the results show that PMF successfully groups elements into factors, and the maps of these factors are visualized. The produced images provide further information on ash interactions and composition of distinct chemical layers. The method can handle all types of chemical maps and the method is not limited solely to SEM-EDX although these images have been used as an example. The main characteristics of the method are: • Adapting graphics and digital images ready for PMF analysis. • Conversion between 1-D and 2-D datasets allows visualization of common chemical maps of elements grouped in factors. • Handles all types of chemical mappings and large data sets
Relaxation of Stress Propagation in Alloying-Type Sn Anodes for K-Ion Batteries
No full textAlloying-type metallic tin is perceived as a potential anode material for K-ion batteries owing to its high theoretical capacity and reasonable working potential. However, pure Sn still face intractable issues of inferior K+ storage capability owing to the mechanical degradation of electrode against large volume changes and formation of intermediary insulating phases K4Sn9 and KSn during alloying reaction. Herein, the TiC/C–carbon nanotubes (CNTs) is prepared as an effective buffer matrix and composited with Sn particles (Sn–TiC/C–CNTs) through the high-energy ball-milling method. Owing to the conductive and rigid properties, the TiC/C–CNTs matrix enhances the electrical conductivity as well as mechanical integrity of Sn in the composite material and thus ultimately contributes to performance supremacy in terms of electrochemical K+ storage properties. During potassiation process, the TiC/C–CNTs matrix not only dissipates the internal stress toward random radial orientations within the Sn particle but also provides electrical pathways for the intermediate insulating phases; this tends to reduce microcracking and prevent considerable electrode degradation
Quasi-monotone convergence of plurisubharmonic functions
Get PDFThe complex Monge-Amp\ue8re operator has been defined for locally bounded plurisubharmonic functions by Bedford-Taylor in the 80\u27s. This definition has been extended to compact complex manifolds, and to various classes of mildly unbounded quasi-plurisubharmonic functions by various authors. As this operator is not continuous for the L1-topology, several stronger topologies have been introduced over the last decades to remedy this, while maintaining efficient compactness criteria. The purpose of this note is to show that these stronger topologies are essentially equivalent to the natural quasi-monotone topology that we introduce and study here
Sorption of Cs, Ba, Co, and Eu onto biotite: experiments and modelling
Get PDFThe sorption of 134Cs, 133Ba, 60Co and 152Eu, all at about [~10-8 M] onto biotite mineral was studied using the batch method with S: L = 1:50 at three different ionic strengths (0.001, 0.01 and 0.1M NaClO4) and five different pH (5,6,7,8,9) at 25\ub0C for up to two months in an inert atmosphere glovebox. The results revealed that the sorption of all metals was dependent on both pH and ionic strength. \ua0At 25\ub0C, the measured sorption distribution coefficients (Rd -values) for 0.001 M were (pH 5-9): (Cs) 0.6-1.2, (Ba) 0.3-8.3, (Co) 0.01-1.9 and (Eu) 2.7-18 m3/kg, respectively. For I = 0.01 M, the corresponding results were (Cs) 0.1-0.7, (Ba) 0.01-4.4, (Co) 0.01-7.5 and (Eu) 0.2-4.3 m3/kg, respectively. For I= 0.1M, the corresponding results were (Cs) 0.01-0.2, (Ba) 0.03-0.4, (Co) 0.01-4.7 and (Eu) 2.1-6.7 m3/kg.\ua0The surface acidity constants for the amphoteric surface site of biotite mineral were determined with the continuous potentiometric titration on a biotite suspension to pKa1= 0.30 and pKa2 = 0.20. These acidity constants were obtained by fitting titration data through the use of PHREEQC and PYTHON code optimization routines.\ua0The biotite size fraction of 0.25-0.5 mm was characterized for acidic site density (ASD), cation exchange capacity (CEC) and the specific surface area (SSA) and were determined to be 6.7mmol/m2, 1.01 \ua00.03 meq/100g and 0.47 m2/g by using tritium uptake, ammonium acetate (NH4Ac), and Kr-BET adsorption methods, respectively.\ua0\ua0To model the experimental sorption data, PHREEQC geochemical modelling software coupled with PYTHON code optimization routines was used. The results shows that a two-step protolysis (2-pKa) non-electrostatic model (NEM) representing edge site with one additional ion-exchange site representing basal plane site is sufficient to reproduce the data for all four metals
Recycling of CIGS solar cells: environmentally friendly approaches for silver and indium recovery
Get PDFThe increase in electricity produced by solar energy is expected to create an end-of-life photovoltaics (PV) waste problem in the following decades, while their manufacturing waste is already a reality. However, their recycling is still at a primitive stage. Among the other PV types, Copper Indium Gallium diSelenide (CIGS) thin film technology can achieve high energy conversion efficiencies, while consuming small amounts of materials. However, the use of critical, precious and toxic elements in this PV technology is a considerable drawback due to risk on sustainable material supply and environmental concerns. Thus, the waste should be treated properly. The scientific literature on waste recycling of indium (In) and silver (Ag) from CIGS solar cells, which is very limited, suggests that their dissolution is accomplished through leaching in acid solutions with high concentrations and, many times, at high temperatures. However, such conditions are not environmentally friendly and can also be costly for the industry. Another challenge on the recycling is the contamination issues from other elements that are usually ignored when recycling of real CIGS PV is investigated.The main focus of this thesis is the recycling of Ag and In (although other elements are studied as well) from flexible CIGS solar cells, using mild leaching conditions. Two processes were tested, both at room temperature: a) a method for leaching of the cell with nitric acid (HNO3) of relatively low concentrations for recovery of Ag and In and b) a method for recovery of Ag and Indium Tin Oxide (ITO) particles using ultrasonic (US) assisted leaching. 100% recovery of Ag and 85% of In was achieved within 24 h when leaching with 2 M HNO3 and surface area to liquid ratio (A:L) equal to 1:3 cm2/ml. However, these results were improved with the second method for a complete recovery of both Ag 95 wt% pure and ITO 70.5 wt% pure. For that, a two-step US-leaching process with 0.1 M HNO3 and A:L equal to 1:3 cm2/ml was used. Both methods offer the advantage of achieving 100% recovery of Ag using relatively benign conditions. Especially the improved US-leaching approach opens up a new path for possible direct reuse of the Ag and ITO particles in the manufacturing of new PVs, after further purification, with an impressively low need for chemicals
Fluorescent Molecular Photoswitches for the Generation of All-Optical Encryption Keys
Get PDFHerein, we report a tri-component photochromic molecular cocktail that can be used to encrypt and decrypt information. The time-dependent fluorescent response of this cocktail is highly non-linear with respect to the set of inputs used (concentrations of the three photochromic components, excitation- and emission wavelengths), a property required for the generation of so-called encryption keys. The all-optical system can generate more than 80 million unique fluorescence responses by applying different input combinations and is operated using a conventional fluorimeter
Application of Biomass-Based Nanomaterials in Energy
Get PDFThe utilization of biomass as a sustainable and renewable resource for nanomaterial synthesis has received considerable attention in recent years. Through the efficient utilization of biomass waste, opportunities for energy production, energy conversion, and the fabrication of nanomaterials can be maximized. The combination of biomass-based nanomaterials with additional nanomaterials makes the composite system have more remarkable performance, which further facilitates the transformation procedure of biomass-based nanomaterials for applications. This comprehensive review provides an overview of the preparation and applications of biomass-based nanomaterials. The preparation section covers a range of methods for synthesizing biomass-based nanomaterials, including biomass-based carbonaceous nanomaterials, biomass-based carbon nitride nanomaterials, nanomaterials derived from biomass templates, biomass-based nanomaterials as carriers, and the use of biomass for metal ion reduction. The applications section explores the diverse applications of biomass-based nanomaterials, such as hydrogen production, carbon dioxide reduction, batteries, and supercapacitors. The unique properties and advantages of biomass-based nanomaterials in each application are discussed. The conclusion summarizes the current progress and presents future perspectives for the development and utilization of biomass-based nanomaterials. This review emphasizes the potential of biomass as a valuable and sustainable source for nanomaterial synthesis, opening up promising opportunities in various fields
Low-Cost Ball-Pen Gap Waveguide With Nearly Zero Friction for Sliding Movements
No full textThis letter presents a novel easy-to-manufacture ball-pen gap waveguide (GW) by utilizing commercial low-cost ball pens to have mechanical reconfigurability. The proposed ball-pen GW consists of a perforated bottom metal plate with ball pens\u27 tips inserted and a flat top plate. Compared with the other noncontact GWs with bed-of-pins structures obtained by milling, the realization of the new ball-pen GW requires only drilling holes on the bottom plate for inserting ball-pen tips to obtain the electromagnetic bandgap property, making it low cost. The more important advantage of the ball-pen GW is to make use of the balls of the ball-pen tips to realize smooth low-friction sliding movements for the mechanical reconfiguration. For the sake of verification, a double 90 degrees bend of the ball-pen GW has been designed, manufactured, and measured. Both simulated and measured results demonstrate its excellent transmission performance and the movable property
Bulky Substituents Promote Triplet-Triplet Annihilation Over Triplet Excimer Formation in Naphthalene Derivatives
Get PDFVisible-to-ultraviolet (UV) triplet-triplet annihilation photochemical upconversion (TTA-UC) has gained a lot of attention recently due to its potential for driving demanding high-energy photoreactions using low-intensity visible light. The efficiency of this process has rapidly improved in the past few years, in part thanks to the recently discovered annihilator compound 1,4-bis((triisopropylsilyl)ethynyl)naphthalene (N-2TIPS). Despite its beneficial TTA-UC characteristics, the success of N-2TIPS in this context is not yet fully understood. In this work, we seek to elucidate what role the specific type and number of substituents in naphthalene annihilator compounds play to achieve the characteristics sought after for TTA-UC. We show that the type of substituent attached to the naphthalene core is crucial for its performance as an annihilator. More specifically, we argue that the choice of substituent dictates to what degree the sensitized triplets form excimer complexes with ground state annihilators of the same type, which is a process competing with that of TTA. The addition of more bulky substituents positively impacts the upconverting ability by impeding excimer formation on the triplet surface, an effect that is enhanced with the number of substituents. The presence of triplet excimers is confirmed from transient absorption measurements, and the excimer formation rate is quantified, showing several orders of magnitude differences between different derivatives. These insights will aid in the further development of annihilator compounds for solar energy applications for which the behavior at low incident powers is of particular significance
Dietary biomarkers-an update on their validity and applicability in epidemiological studies
Get PDFThe aim of this literature review was to identify and provide a summary update on the validity and applicability of the most promising dietary biomarkers reflecting the intake of important foods in the Western diet for application in epidemiological studies. Many dietary biomarker candidates, reflecting intake of common foods and their specific constituents, have been discovered from intervention and observational studies in humans, but few have been validated. The literature search was targeted for biomarker candidates previously reported to reflect intakes of specific food groups or components that are of major importance in health and disease. Their validity was evaluated according to 8 predefined validation criteria and adapted to epidemiological studies; we summarized the findings and listed the most promising food intake biomarkers based on the evaluation. Biomarker candidates for alcohol, cereals, coffee, dairy, fats and oils, fruits, legumes, meat, seafood, sugar, tea, and vegetables were identified. Top candidates for all categories are specific to certain foods, have defined parent compounds, and their concentrations are unaffected by nonfood determinants. The correlations of candidate dietary biomarkers with habitual food intake were moderate to strong and their reproducibility over time ranged from low to high. For many biomarker candidates, critical information regarding dose response, correlation with habitual food intake, and reproducibility over time is yet unknown. The nutritional epidemiology field will benefit from the development of novel methods to combine single biomarkers to generate biomarker panels in combination with self-reported data. The most promising dietary biomarker candidates that reflect commonly consumed foods and food components for application in epidemiological studies were identified, and research required for their full validation was summarized