Calorimetry Data Research Articles

Non-destructive evaluation of the curing of a polybenzoxazine nanocomposite blend for space applications using fluorescence spectroscopy and predictive mechanical modelling

In this study, we employ fluorescence spectroscopy to monitor the curing process of a novel polybenzoxazine (PBZ) resin blend containing a polyhedral oligomeric silsesquioxane (POSS) reagent in a non-destructive way and compare it with the differential scanning calorimetry data. Our resin blend has been carefully selected for study on the International Space Station in 2024 as part of the Euro Materials Ageing 1 Programme (AO-2020-EMA) supported by the European Space Agency (ESA) and the French Space Agency (CNES). Computational simulations of PBZ-POSS blend composites are investigated to determine their effective mechanical responses based on constituent micro-stresses with periodic boundary conditions and continuum-based analytical micromechanical models. Further investigations are focused on the development of different representative volume element models, including periodic, non-periodic, and overlap inclusions, and the comparison with experimental data. Fluorescence spectroscopy and computational and analytical methods can offer a non-destructive approach to gaining insights into polymerisation processes and effective mechanical responses.

Impact of heat-set and cold-set gelling polysaccharides on potato protein gelation: Gellan gum, agar, and methylcellulose

The plant-based meat market is growing due to concerns about the sustainability of the modern food system. Plant-based meats are often constructed from blends of food biopolymers, such as plant proteins and polysaccharides. This study characterizes the thermal setting properties of potato protein (10%) and polysaccharide (2 wt%) mixtures containing polysaccharides with different reversible gelling behaviors: agar (cold set); gellan gum (cold set); or methyl cellulose (heat set). Each sample was heated above the thermal denaturation temperature of the potato proteins to promote protein unfolding, aggregation, and network formation. The addition of the polysaccharides tended to increase the complex shear modulus of the biopolymer blends before heating but increase or decrease it after heating depending on polysaccharide type. The shear modulus and hardness of the gels formed after heating tended to increase after addition of the cold-set polysaccharides but decrease after the addition of the heat-set polysaccharides, especially at refrigerator temperatures. Differential scanning calorimetry data showed that the potato proteins underwent irreversible denaturation after heating for all samples. Zeta-potential analysis showed that the potato proteins and all polysaccharides were negatively charged under the pH conditions used. There was greater water loss during heating for the composite gels containing methyl cellulose, which may have been due to its increase hydrophobicity at high temperatures. Appearance and microstructure analysis showed that phase-separation occurred after mixing the polysaccharides with the potato proteins, which was attributed to a segregation mechanism. The knowledge obtained from this study may help the food industry to optimize protein-polysaccharide blends to create gels with characteristics and structures that can mimic different plant-based meat products.

Change in the Kinetic Regime of Aggregation of Yeast Alcohol Dehydrogenase in the Presence of 2-Hydroxypropyl-β-cyclodextrin.

Chemical chaperones are low-molecular-weight compounds that suppress protein aggregation. They can influence different stages of the aggregation process-the stage of protein denaturation, the nucleation stage and the stage of aggregate growth-and this may lead to a change in the aggregation kinetic regime. Here, the possibility of changing the kinetic regime in the presence of a chemical chaperone 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD) was investigated for a test system based on the thermally induced aggregation of yeast alcohol dehydrogenase (yADH) at 56 °C. According to differential scanning calorimetry data, 2-HP-β-CD did not affect the stage of the protein molecule unfolding. Dynamic light scattering data indicated changes in the aggregation kinetics of yADH during the nucleation and aggregate growth stages in the presence of the chaperone. The analysis of kinetic curves showed that the order of aggregation with respect to protein (nc), calculated for the stage of aggregate growth, changed from nc = 1 to nc = 2 with the addition of 100 mM 2-HP-β-CD. The mechanism of 2-HP-β-CD action on the yADH thermal aggregation leading to a change in its kinetic regime of aggregation is discussed.

The Fragility of Glassy Corn Starches

The fragility m of starches derived from corn and waxy corn, dried at various temperatures are computed with different water contents and heating rates (1,3,5,7,10, and 15 K/min) using Differential Scanning Calorimetry (DSC) data. Three theoretical approaches namely, Augis & Bennett, Lasocka and Vogel-Fulcher-Tammanni (VFT) are utilized to fit the DSC gelatinization transition temperature, TgT data to calculate the fragility m. The fragility m at a 7 K/min heating rate, with water contents from 30 to 90% at drying temperature 20 °C for corn starch is in the range 41 to 68, whereas at drying temperature of 100 °C for the same corn starch remains constant around 42. The waxy corn starch having water contents 50 to 90% and at drying temperatures 70 °C and 90 °C, the fragility m is unstable. On the whole, fragility m is in between 39 and 63 and according to the Angell’s criterion (16<m<100) the corn starches are intermediately strong glasses.

Bayesian Regression Quantifies Uncertainty of Binding Parameters from Isothermal Titration Calorimetry More Accurately Than Error Propagation.

We compare several different methods to quantify the uncertainty of binding parameters estimated from isothermal titration calorimetry data: the asymptotic standard error from maximum likelihood estimation, error propagation based on a first-order Taylor series expansion, and the Bayesian credible interval. When the methods are applied to simulated experiments and to measurements of Mg(II) binding to EDTA, the asymptotic standard error underestimates the uncertainty in the free energy and enthalpy of binding. Error propagation overestimates the uncertainty for both quantities, except in the simulations, where it underestimates the uncertainty of enthalpy for confidence intervals less than 70%. In both datasets, Bayesian credible intervals are much closer to observed confidence intervals.

Validation of a musculoskeletal model for simulating muscle mechanics and energetics during diverse human hopping tasks.

Computational musculoskeletal modelling has emerged as an alternative, less-constrained technique to indirect calorimetry for estimating energy expenditure. However, predictions from modelling tools depend on many assumptions around muscle architecture and function and motor control. Therefore, these tools need to continue to be validated if we are to eventually develop subject-specific simulations that can accurately and reliably model rates of energy consumption for any given task. In this study, we used OpenSim software and experimental motion capture data to simulate muscle activations, muscle fascicle dynamics and whole-body metabolic power across mechanically and energetically disparate hopping tasks, and then evaluated these outputs at a group- and individual-level against experimental electromyography, ultrasound and indirect calorimetry data. Comparing simulated and experimental outcomes, we found weak to strong correlations for peak muscle activations, moderate to strong correlations for absolute fascicle shortening and mean shortening velocity, and strong correlations for gross metabolic power. These correlations tended to be stronger on a group-level rather than individual-level. We encourage the community to use our publicly available dataset from SimTK.org to experiment with different musculoskeletal models, muscle models, metabolic cost models, optimal control policies, modelling tools and algorithms, data filtering etc. with subject-specific simulations being a focal goal.

Computed Protein-Protein Enthalpy Signatures as a Tool for Identifying Conformation Sampling Problems.

Understanding the thermodynamic signature of protein-peptide binding events is a major challenge in computational chemistry. The complexity generated by both components possessing many degrees of freedom poses a significant issue for methods that attempt to directly compute the enthalpic contribution to binding. Indeed, the prevailing assumption has been that the errors associated with such approaches would be too large for them to be meaningful. Nevertheless, we currently have no indication of how well the present methods would perform in terms of predicting the enthalpy of binding for protein-peptide complexes. To that end, we carefully assembled and curated a set of 11 protein-peptide complexes where there is structural and isothermal titration calorimetry data available and then computed the absolute enthalpy of binding. The initial "out of the box" calculations were, as expected, very modest in terms of agreement with the experiment. However, careful inspection of the outliers allows for the identification of key sampling problems such as distinct conformations of peptide termini not being sampled or suboptimal cofactor parameters. Additional simulations guided by these aspects can lead to a respectable correlation with isothermal titration calorimetry (ITC) experiments (R2 of 0.88 and an RMSE of 1.48 kcal/mol overall). Although one cannot know prospectively whether computed ITC values will be correct or not, this work shows that if experimental ITC data are available, then this in conjunction with computed ITC, can be used as a tool to know if the ensemble being simulated is representative of the true ensemble or not. That is important for allowing the correct interpretation of the detailed dynamics of the system with respect to the measured enthalpy. The results also suggest that computational calorimetry is becoming increasingly feasible. We provide the data set as a resource for the community, which could be used as a benchmark to help further progress in this area.

Phase transitions, thermal, vibrational (FT-IR and Raman) and optical characterizations, dielectric relaxation and electrical conductivity of a cobalt (II) based hybrid material

The combination of various organic molecules and inorganic fragments into a single hybrid crystalline lattice has sparked much attention for the potential physical properties and applications. The present investigation addresses the characterization of a novel crystalized compound, formulated as (C7H11N2)2CoCl4. In order to characterize the various types of intermolecular interactions in the title compound, the interaction variability of the two independent cations and four chloride atoms is checked via Hirshfeld surface analysis. Indeed, phase structures were characterized using thermogravimetric analysis, differential scanning calorimetry, Infrared and Raman data. Furthermore, UV−vis and PL measurements revealed a semiconductor character of the obtained compound. The calculated direct and indirect band gaps (Egd, Egi) were predicted to be 1.45 and 1.56 eV, respectively. In addition, a phase transition was discovered by thermal analysis at 390 K, and comprehensive dielectric research showed a good agreement with thermal data. Impedance spectroscopy measurements were used to study the electrical and dielectric characteristics of the title compound over a wide range of frequencies and temperatures, 40 Hz–10 MHz and 313–483 K, respectively. The Nyquist plot (Z" versus Z′) from the complex impedance spectrum revealed semicircular arcs described by a Cole-Cole model. Using the Z-view software, a series of Nyquist representations were built and fitted to an equivalent circuit that reflected the behavior of this material. The thermal evolution of the conductivity follows an Arrhenius-type behavior. Also, the real and imaginary parts of dielectric permittivity of (C7H11N2)2CoCl4 at different frequencies were discussed. The presence of grain and grain boundaries is confirmed by the modulus investigations. Electric and dielectric analyses highlight the good protonic conduction of this material.

Thermal, mechanical and electrical performance of structural epoxy resins filled with carbon nanofibers

Carbon nanofibers (CNFs) were heat-treated at 1100 °C (CNF1100) and 2500 °C (CNF2500), respectively, and embedded as fillers at different mass percentages into an epoxy mixture. The paper aims at evaluating, through a comparison between the two different types of resulting nanocomposites, the influence of the CNF heat treatment on the thermal, mechanical, and electrical performance of the formulated samples. Thermogravimetric analysis (TGA) showed oxidative stability in the air of CNF2500 approximately 200 °C higher than the CNF1100 ones. The first oxidation stage of the resins embedding the two typologies of CNFs falls between 380 and 480 °C. This means that the temperature of the heat treatment of the nanofiller does not influence the temperature at which the thermodegradation of the nanocomposites starts. Differential Scanning Calorimetry (DSC) data show that the highest degree of cure (DC) was recorded for the epoxy samples filled with CNF2500. CNF thermal treatment increases the direct current (dc) conductivity of the nanocomposite by 3 orders of magnitude around the electrical percolation threshold (EPT) and increases the storage modulus of the CNF2500-based resins up to 60 °C compared with the unfilled resin. The peculiar wall structure of CNF1100 determines a further slight enhancement. Tunneling Atomic Force Microscopy (TUNA) reveals that the CNFs are evenly distributed on the nanodomains showing higher electric current values for samples loaded with CNF2500.

Synthesis and characterization of granite dust microparticles reinforced bio-benzoxazine composites

In the current work, an effort has been made to create polymer composite materials using polybenzoxazine (PBz), which is synthesis from sustainable natural ingredients like furfurylamine (Fu), cardanol (Ca) and reinforced with granite dust made from industrial waste. Varied analytical approaches were used to examine the thermal, morphological, chemical structure, flame retardant and electrical properties of Ca-Fu-PBZ composites reinforced with granite dust at varied weight percentages (5, 10, 15 and 20 wt%). According to the weight percentage concentration of granite dust, the differential scanning calorimetry (DSC) data suggest that the value of Tg increased from 105 to 139°C. A pure Ca-Fu-PBZ benzoxazine matrix was found to have a dielectric constant of 3.97 at 1 MHz. Whereas 5, 10 and 20 wt percentages of reinforced Ca-Fu-PBZ composites with granite dust had dielectric constants of 3.54, 3.05, 2.51 and 2.02 at 1 MHz, respectively. For granite dust reinforced Ca-Fu-PBZ polybenzoxazine composites, the value of the limiting oxygen index (LOI) determined for the char yield obtained thermogravimetric analysis (TGA) shows greater values than those of the neat Ca-Fu-PBZ matrices. Using water contact angle, the hydrophobic behavior of polybenzoxazine composites reinforced with granite dust was investigated, and it was concluded that the hydrophobic behavior increased with the weight % of granite dust. Data from several investigations show that the thermally stable electrical insulation applications can employ the granite dust reinforced sustainable cardanol-furfurylamine based polybenzoxazine composites as potting compounds, sealants and composites.

Thermal hazard assessment of one-step synthesis pentazolate anion by calorimetry data

Thermal hazard assessment of one-step synthesis pentazolate anion by calorimetry data

Modelling the Decamerisation Cycle of PRDX1 and the Inhibition-like Effect on Its Peroxidase Activity.

Peroxiredoxins play central roles in the detoxification of reactive oxygen species and have been modelled across multiple organisms using a variety of kinetic methods. However, the peroxiredoxin dimer-to-decamer transition has been underappreciated in these studies despite the 100-fold difference in activity between these forms. This is due to the lack of available kinetics and a theoretical framework for modelling this process. Using published isothermal titration calorimetry data, we obtained association and dissociation rate constants of 0.050 µM-4·s-1 and 0.055 s-1, respectively, for the dimer-decamer transition of human PRDX1. We developed an approach that greatly reduces the number of reactions and species needed to model the peroxiredoxin decamer oxidation cycle. Using these data, we simulated horse radish peroxidase competition and NADPH-oxidation linked assays and found that the dimer-decamer transition had an inhibition-like effect on peroxidase activity. Further, we incorporated this dimer-decamer topology and kinetics into a published and validated in vivo model of PRDX2 in the erythrocyte and found that it almost perfectly reconciled experimental and simulated responses of PRDX2 oxidation state to hydrogen peroxide insult. By accounting for the dimer-decamer transition of peroxiredoxins, we were able to resolve several discrepancies between experimental data and available kinetic models.

Self-pressurized rapid freezing at arbitrary cryoprotectant concentrations.

Self-pressurized rapid freezing (SPRF) has been proposed as a simple alternative to traditional high pressure freezing (HPF) protocols for vitrification of biological samples in electron microscopy and cryopreservation applications. Both methods exploit the circumstance that the melting point of ice reaches a minimum when subjected to pressure of around 210 [MPa], however, in SPRF its precise quantity depends on sample properties and hence, is generally unknown. In particular, cryoprotective agents (CPAs) are expected to be a factor; though eschewed by many SPRF experiments, vitrification of larger samples notably cannot be envisaged without them. Thus, in this study, we address the question of how CPA concentration affects pressure inside sealed capillaries, and how to design SPRF experiments accordingly. By embedding a fiber-optic probe in samples and performing Raman spectroscopy after freezing, we first present a direct assessment of pressure buildup during SPRF, enabled by the large pressure sensitivity of the Raman shift of hexagonal ice. Choosing dimethyl sulfoxide (DMSO) as a model CPA, this approach allows us to demonstrate that average pressure drops to zero when DMSO concentrations of 15 wt % are exceeded. Since a trade-off between pressure and DMSO concentration represents an impasse with regards to vitrification of larger samples, we introduce a sample architecture with two chambers, separated by a partition that allows for equilibration of pressure but not DMSO concentrations. We show that pressure and concentration in the fiber-facing chamber can be tuned independently, and present differential scanning calorimetry (DSC) data supporting the improved vitrification performance of two-chamber designs. Lay version of abstract for "Self-pressurized rapid freezing at arbitrary cryoprotectant concentrations" Anyone is familiar with pipes bursting in winter because the volume of ice is greater than that of liquid water. Less well known is the fact that inside a thick-walled container, sealed and devoid of air bubbles, this pressure buildup will allow a fraction of water to remain unfrozen if the sample is also cooled sufficiently rapidly far below the freezing point. This phenomenon has already been harnessed for specimen preparation in microscopy, where low temperatures are useful to immobilize the sample, but harmful if ice-formation occurs. However, specimen preparation cannot always rely on this pressure-based effect alone, but sometimes requires addition of chemicals to inhibit ice-formation. Not enough is known directly about how these chemicals affect pressure buildup: Indeed, rapid cooling below the freezing point is only possible for small sample volumes, typically placed inside sealed capillaries, so that space is generally insufficient to accommodate a pressure sensor. By means of a compact sensor, based on an optical fiber, laser and spectrometer, we present the first direct assessment of pressure inside sealed capillaries. We show that addition of chemicals reduces pressure build-up and present a two-chambered capillary to circumvent the resulting trade-off. Also, we present evidence showing that the two-chambered capillary design can avoid ice-formation more readily than a single-chambered one. This article is protected by copyright. All rights reserved.

The Effect of Baghouse Dust from Secondary Aluminum Processing Waste on Cement Hydration and Mechanical Properties

This work studies the mechanical and chemical effects of utilizing baghouse dust (BHD) from secondary aluminum processing waste as a cement additive for potential use in concrete materials. The baghouse dust was added to cement pastes at replacements of 4 % and 8 % by cement mass. In addition, a combination of BHD and silica fume at different blended ratios were added to the cement mixture as a combined additive. Some reference proportions were also prepared for a comprehensive comparison. Unconfined compressive strength and the chemical composition of the extracted pore solution of the abovementioned hardened cement pastes were investigated. In addition, the effect of BHD on the hydration characteristics of the cement paste was also observed through isothermal calorimetry. It was found that an 8 % substitution of cement by BHD resulted in increased compressive strength after 1 day and 3 days of curing and a reduction of less than 2 % at 7 days of curing. Comparatively, samples with 8 % silica fume resulted in a strength increase of 17 %. As such, it was concluded that BHD addition of up to 8 % was not detrimental to concrete strength but did not improve performance either. This finding was supported by isothermal calorimetry data, which showed that the addition of BHD and the addition of silica fume both increased the initial peak of hydration and accelerated the hydration process but did not significantly impact the total energy of hydration over a period of 7 days. Finally, the high chloride content in BHD may promote corrosion in steel bars and increase concrete scaling potential.

Observation and modeling of the thermal runaway of high-capacity pouch cells due to an internal short induced by an indenter

Owing to the complexity of coupling mechanical and electrical solvers for finite element analysis (FEA) of mechanical abuse of a battery, the simulation should be performed by incorporating a local short circuit model activated based on the status of battery elements. However, the approach should also consider various other conditions of the battery simulated, such as the initial state of charge (SOC), for precise simulations of the internal short. This study proposes an approach developed with a mechanical model and single-particle battery model, along with a reaction kinetics model for thermal abuse using LS-DYNA. Several key parameters were selected, such as the activation criteria, kinetic abuse and element integration points during the internal short circuit induced by the indenter. The impact of these key parameters in the FEA on thermal runaway response for various initial SOCs from 25to 100 % were analyzed. The FEA results obtained were compared against experimental results with various parameters such as activation criterion of internal short, kinetic abuse based on accelerating rate calorimetry (ARC) data. Finally, the root causes of the discrepancy between the FEA and experimental results are discussed regarding integration point what solver can make difference during calculation.

Synthesis of lignin nanoparticles from Oxytenanthera abyssinica by nanoprecipitation method followed by ultrasonication for the nanocomposite application

Lignin nanoparticles (LNPs) have a wide range of potential uses in the biomedical and environmental fields. They are used to prepare antioxidants, food packaging material, energy storage, cosmetics, thermal/light stabilizers, reinforced materials, and drug delivery. In this study, LNPs were prepared from soda lignin obtained from Oxytenanthera abyssinica using dioxane, acetone, ethanol, and acid-base solvents through the nanoprecipitation method, followed by an ultrasonic process. These methods produced four different LNPs with yields in the range of 28.5% to 88.9%. Scanning electron microscope (SEM) showed that the spherical-shaped LNPS (100–400 nm) were obtained using the acetone solvent, while irregularly shaped LNPs were formed by dioxane (150–400 nm), ethanol (40–200 nm) and acid-base (100–800 nm) solvents. The maximum zeta potential of the LNPAS samples was |-35.1 mV|, determined by the dynamic light scattering (DLS), with a particle size distribution between 91.28 and 458.7 nm. According to the energy-dispersive X-ray spectrometer (EDX) results, the sample contains the elements C, O, Si, Na, and Mo. X-ray powder diffraction (XRD) analysis showed very small crystallinity sizes ranging from 0.31 to 0.35 nm. Proton nuclear magnetic resonance (H-NMR) and Fourier transformation infrared Spectroscopy (FTIR) were used to find the functional groups in the synthesized LNPs. The Thermogravimetric analysis (TGA) peak showed that LNPS was thermally stable, and rapid mass loss occurred between 300 and 415 °C. Differential Scanning Calorimetry (DSC) data shows that the highest exothermic peaks are obtained at 345.2 °C. Synthesis of LNPs by dissolving isolated soda lignin in acetone, ethanol, dioxane, and acid-base solvents was quickly recovered, cheap, and eco-friendly. The synthesized are free of sulfur; they do not use toxic solvents such as Tetrahydrofuran (THF), Dimethyl sulfoxide (DMSO), and Dimethylformamide (DMF). Thus, they provide benefits for high-value-added Nanocomposite applications such as bio-based nonmaterial and food packaging materials. Acid-base nanoprecipitation procedure is the best approach regarding stability and size, but the acetone nanoprecipitation method is preferable regarding shape.

Impact of methods for data selection on the day-to-day reproducibility of resting metabolic rate assessed with four different metabolic carts

Background and aimsAccomplishing a high day-to-day reproducibility is important to detect changes in resting metabolic rate (RMR) and respiratory exchange ratio (RER) that may be produced after an intervention or for monitoring patients' metabolism over time. We aimed to analyze: (i) the influence of different methods for selecting indirect calorimetry data on RMR and RER assessments; and, (ii) whether these methods influence RMR and RER day-to-day reproducibility. Methods and resultsTwenty-eight young adults accomplished 4 consecutive RMR assessments (30-min each), using the Q-NRG (Cosmed, Rome, Italy), the Vyntus CPX (Jaeger-CareFusion, Höchberg, Germany), the Omnical (Maastricht Instruments, Maastricht, The Netherlands), and the Ultima CardiO2 (Medgraphics Corporation, St. Paul, Minnesota, USA) carts, on 2 consecutive mornings. Three types of methods were used: (i) short (periods of 5 consecutive minutes; 6–10, 11–15, 16–20, 21–25, and 26–30 min) and long time intervals (TI) methods (6–25 and 6–30 min); (ii) steady state (SSt methods); and, (iii) methods filtering the data by thresholding from the mean RMR (filtering methods). RMR and RER were similar when using different methods (except RMR for the Vyntus and RER for the Q-NRG). Conversely, using different methods impacted RMR (all P ≤ 0.037) and/or RER (P ≤ 0.009) day-to-day reproducibility in all carts. The 6–25 min and the 6–30 min long TI methods yielded more reproducible measurements for all metabolic carts. ConclusionThe 6–25 min and 6–30 min should be the preferred methods for selecting data, as they result in the highest day-to-day reproducibility of RMR and RER assessments.

Fast heating inhibits endothermic solid-solid polymorphic transition giving a melting of low temperature polymorph with the next cold crystallization

Heating at the rate of several hundred Kelvin per second in fast scanning calorimetry (FSC) experiments was found to change the route of polymorphic transformation. Upon the increase of the heating rate first the endothermic solid-state polymorphic transition is hindered to give a consecutive melting of low-temperature form and crystallization of high temperature polymorph. At higher heating rates, only melting of low-temperature polymorph is observed much below an equilibrium melting point. This thermal behavior with depression of final melting point by 30 K was observed for tert‑butylthiacalix[4]arene tetrasubstituted with (ethoxycarbonyl)methoxy groups (1), which does not sublimate at heating. A similar shift of the endothermic solid-state polymorphic transition by temperature at fast heating was found for caffeine (2), however the melting of low-temperature polymorph is not observed due to sublimation of the compound at elevated temperatures. The heating rates, at which a significant depression of the melting points of 1 and 2 may be expected in absence of sublimation, were calculated using equations of thermal kinetics derived from the data of conventional differential scanning calorimetry. The results give a practical guide for the preparation of glassy forms of the substances capable of endothermic solid-solid transition below melting point of high-temperature form.

Alternative alkali activator from pulp mill waste – One-part blast furnace slag mortar activated with recovery boiler fly ash

Alternative alkali activators are a growing research area in the field of alkali-activated materials (AAMs) because conventional chemical-based activators, such as sodium hydroxide and sodium silicate, have a large environmental footprint and high costs. Industrial residues are widely studied as substitutional cementitious materials in concrete and precursors in AAMs but not much as activators. In the present study, sodium rich waste from pulp mill was used as an alkali source in AAMs. Recovery boiler fly ash (RBA) is dust-like waste fraction removed from flue gases of recovery boiler by electrostatic precipitators. It consists mainly of alkalis, sulfate, and carbon while sodium sulfate is the main phase. This work utilized RBA as a sole one-part alkali activator for a precursor mixture containing 95 wt% of blast furnace slag and 5 wt% of cement, and the results were compared with two references, one without activator and the other activated with commercial sodium sulfate. The setting properties and strength gain were comparable between the RBA-activated and commercial activator-activated samples. Calorimetry data showed also similar reactivity between them, and X-ray diffractometry, thermogravimetric analysis, and scanning electron microscopy measurements revealed that the same phases were formed. The main issue was the microcracking of the paste samples when using RBA as an activator. Results confirm the earlier findings from the literature, the activator dosage did not greatly impact the properties: in this study, the initial proportion of 1% or 3% Na2O was the most suitable.

Precious metal amorphous AgAuSi: Alloy design by swapping gold for silver

To expand the basis for property-oriented material design, complex relationships between chemistry, atomistic structure, and properties of sputter-deposited AgxAu85-xSi15 alloys are investigated using versatile experimental methods. According to differential scanning calorimetry and X-ray diffraction data, the alloys are amorphous within a wide compositional range of 20 ≤ x ≤ 60 at%. However, high-resolution transmission electron microscopy revealed noticeable amounts of crystallites in limiting compositions with x = 20 at% and x = 60 at%. Glass transition and crystallization temperatures grow with increasing Ag content, while room-temperature resistivity and temperature coefficient of resistance are shown to be highly sensitive to the amount of crystalline phase. Neither the existence of nanocrystallites nor the substitution of Ag by Au affected significantly the mechanical properties. All compositions exhibit similar nanoindentation hardness of about 4.3 GPa, Young’s modulus of about 55 GPa, and macroscopic elastic limit of about 2%. The unique combination of high hardness, high elastic strain but low Young’s modulus together with the expected chemical inertness inherited from noble metals makes this alloy family suitable for biomedical applications in form of coatings or in jewelry if an economic bulk production route will be developed.