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Mn2+ coordinated by orthophosphate (Pi), metabolites, or peptides acts as a superoxide dismutase (SOD), and these Mn antioxidant complexes are universally accumulated in extremely radiation-resistant cell types across the tree of life. This behavior prompted design of decapeptide DP1 (DEHGTAVMLK) as a Mn2+ ligand, and development of a highly potent Mn2+-antioxidant (MDP) containing [Pi] = 25 mM, and [DP1] = 3 mM, the ratio found in the radioresistant bacterium Deinococcus radiodurans, with [Mn2+] = 1 mM. MDP is an exceptional antioxidant, both in vitro and in vivo, and has reinvigorated the development of radiation-inactivated whole-cell vaccines. This study investigates the nature of the active Mn2+ complex in MDP. We measure the affinity of DP1 for the substitutionally labile Mn2+ ion using isothermal-titration calorimetry (ITC) and use changes in the Mn2+ solution EPR spectrum to determine affinities of Mn2+ for DP1 and for Pi, and to monitor Mn2+ ligation while titrated with the fixed Pi/DP1 ratio of MDP, 25/3, using ENDOR/ESEEM to characterize DP1 ligation to Mn2+. In parallel, 1H NMR of DP1 was used to monitor binding interactions between Pi and DP1, and DP1 binding to the diamagnetic Ca2+. We report: i) DP1 forms an extremely weak, dynamic Mn2+ complex (Ka ≈ 40 M-1) ii) Mn2+ binds Pi much more strongly (Ka ≈ 390 M-1) as shown previously, but iii) DP1 and Pi jointly bind to Mn2+ in MDP to form a ternary Mn2+ (Pi) (DP1) complex with greater formation-constant than Pi alone (Ka app ≈ 670 M-1). It is this ternary complex that is the superb antioxidant in MDP. [ABSTRACT FROM AUTHOR]

Using solid waste-based materials, such as recycled building aggregate (RCA), preparing 3D-printed materials can reduce costs but increase the water–cement ratio of the printed material, which reduces its mechanical performance. In order to solve the problem of mechanical properties decline caused by an increase in the w/c ratio, this experiment found that adding calcined salt mud (CSM) to the printing materials and changing the water-to-cement ratio from 0.37 to 0.4 CSM can ensure that the compressive strength of the printing materials remains basically unchanged. Moreover, through TG, SEM, and other microscopic data, it can be seen that calcium hydroxide in CSM can not only participate in the synergistic reaction of ethylene/vinyl acetate copolymer (EVA) and dust ash (DA), produce more NaOH, and promote the hydration of granulated blast furnace slag (GBFS) but also promote the formation of ettringite together with SO42− in solution, optimizing pore size distribution. [ABSTRACT FROM AUTHOR]

This study examines the impact of sodium citrate and a plasticizing additive, along with their sequential introduction into a cement slurry or concrete mix, on the heat evolution of the cement slurry, the microstructure, phase composition of the cement paste, and the compressive strength of fine-grained concrete. The binder used in this research was a blended binder consisting of 90% Portland cement and 10% calcium aluminate cement. This type of binder is characterized by an increased heat evolution and accelerated setting time. The addition of sodium citrate at 5% of the binder mass alters the phase composition of newly formed compounds by increasing the quantity of AFt and AFm phases. The presence of sodium citrate significantly delays the hydration process of tricalcium silicate by a factor of 3.3. Initially, it accelerates belite hydration by 31.6%, but subsequently slows it down, with a retardation of 43.4% observed at 28 days. During the hardening process, the hydration of tricalcium aluminate and tetracalcium aluminoferrite is accelerated throughout the hardening process, with the maximum acceleration occurring within the first 24 h. During the first 24 h of hydration, the dissolution rates of tricalcium aluminate and tetracalcium aluminoferrite were 40.7% and 75% faster, respectively. Sodium citrate enhances heat evolution during the initial 24 h by up to 4.3 times and reduces the induction period by up to 5 times. Furthermore, sodium citrate promotes early strength development during the initial curing period, enhancing compressive strength by up to 6.4 times compared to the reference composition. [ABSTRACT FROM AUTHOR]

This paper examines the properties of sewage sludge ashes (SSAs) from the incineration of sewage sludge with added limestone for toxic gas treatment. It also evaluates the potential valorization of SSA in cement composites as supplementary cementitious materials (SCMs). The work involves a thorough characterization of four SSAs, including physical, chemical, and mineralogical properties. It also includes assessing the behavior of SSA in water solution through electrical conductivity measurements. The reactivity of ashes was evaluated using the R3 method and mechanical properties. The results revealed that all SSAs present comparable mineralogical and chemical properties, with varying proportions. Major elements such as Ca, Si, Fe, P, and S are predominant in the ashes, with traces of heavy metals. In an aqueous solution, a gradual formation of ettringite was detected only for two SSA. The heavy metal leachability was negligible, confirming that SSA is a non-hazardous waste. Finally, the reactivity and strength activity index assessments revealed a low and slow reactivity of SSA compared to metakaolin or slag. The SSA that favored ettringite formation in aqueous solution presented the lowest compressive strength at 28 days after incorporation in mortar. Despite originating from different incineration sites, these ashes fall under the same category of SCM reactivity.

The rise in early-age temperature concrete structures, driven by the exothermic reactions during cement hydration, significantly increases the risk of thermal cracking. To address this issue, the construction industry employs several strategies, including the partial substitution of cement with ground granulated blast furnace slag (GGBS) due to its lower heat of hydration. Accurately predicting the hydration temperature of concrete is critical for preventing thermal cracking. This task becomes more complex, with fluctuating ambient temperatures influencing hydration kinetics and heat dissipation. Previous studies often assume adiabatic or isothermal conditions, thus overlooking the impact of ambient temperature variations. This paper presents an innovative finite element modelling (FEM) approach to simulate the hydration temperature progression in in situ concrete slabs, incorporating the effects of ambient temperature fluctuations. Isothermal calorimetry curves were adjusted using the Arrhenius-based approach to express the cement hydration rate as a function of ambient temperature. The FEM outcomes, validated with semi-adiabatic calorimetry tests, demonstrate the model’s capability to forecast temperature development in in situ concrete under varying ambient conditions. Additionally, the study examines the influence of partial cement replacement with GGBS on thermal behaviour, revealing that while GGBS effectively reduces thermal reactions at higher contents, its efficacy diminishes with rising ambient temperatures.

This paper presents an experimental approach to the study of the compressive strength, isothermal calorimetry and life cycle assessment (LCA) of alkali-activated pastes based on soda–lime–silica glass, established to investigate the effect of the nature and proportion of the activator. Four different activators are compared: Portland cement, sodium silicate, sodium carbonate (at four percentages by weight: 5, 10, 15 and 25 wt% relative to glass) and sodium hydroxide (3.5 wt%). Portland cement and sodium carbonate were added in dry form (powder), while sodium hydroxide (pellets) and silicate were used in solution. At room temperature, glass exhibited slow reaction kinetics, with mechanical performance increasing significantly beyond 28 days of curing. The nature of the activator had a direct impact on the mechanical performance of the activated glass. Cement-activated pastes and those containing 25 wt% of sodium carbonate developed strength at an early age (0–7 days). The other activators showed lower strength development before 28 days of reaction. While a higher activator content improved short-term performance, it also increased the environmental impact, primarily due to the activator. The LCA, conducted on 11 indicators, revealed that the environmental impact was largely driven by the type and amount of activator used. A performance impact indicator (PII) related to global warming was introduced to compare pastes with different performance values. At an early age (0–28 days), the PII was lower when the activator level was high but decreased over time as the strength improved. In terms of long-term performance (360 days), hydroxide and sodium carbonate (10 wt%) achieved compressive strengths of 91 and 74 MPa, respectively. These systems offered a balance between high performance and a reduced environmental impact, making them of interest for sustainable applications. [ABSTRACT FROM AUTHOR]

The paper deals with analyzes of Isothermal Conduction Calorimetry response obtained during the alkaline activation of four types of precursors (metakaolin, slag and two kinds of waste ceramic powders) to geopolymers. The first two precursors are traditionally used, while the latter two are emerging materials and knowledge of their alkaline activation might have high importance in the recycling of Construction and Demolition Waste. The studied precursors differ each to other not only in the chemical composition, but also in the phase composition—the waste ceramic precursors are highly crystalline. It was found that the total reaction heat evolved in the geopolymerization is directly proportional to the amorphous matter content as well as to the compressive strength of the activated product. This finding can be used as fast evaluation tool in searching of new potential geopolymer precursors. The dissolution and polycondensation steps were observed in all experiments and their kinetics was described by Jander's equation. While the rate of dissolution step is not dependent on temperature, the polycondensation has been accelerated by the higher temperature. The level of the rate acceleration was described by apparent activation energy; these findings can be useful in tuning of geopolymers curing procedure. [ABSTRACT FROM AUTHOR]

The rise in early-age temperature concrete structures, driven by the exothermic reactions during cement hydration, significantly increases the risk of thermal cracking. To address this issue, the construction industry employs several strategies, including the partial substitution of cement with ground granulated blast furnace slag (GGBS) due to its lower heat of hydration. Accurately predicting the hydration temperature of concrete is critical for preventing thermal cracking. This task becomes more complex, with fluctuating ambient temperatures influencing hydration kinetics and heat dissipation. Previous studies often assume adiabatic or isothermal conditions, thus overlooking the impact of ambient temperature variations. This paper presents an innovative finite element modelling (FEM) approach to simulate the hydration temperature progression in in situ concrete slabs, incorporating the effects of ambient temperature fluctuations. Isothermal calorimetry curves were adjusted using the Arrhenius-based approach to express the cement hydration rate as a function of ambient temperature. The FEM outcomes, validated with semi-adiabatic calorimetry tests, demonstrate the model's capability to forecast temperature development in in situ concrete under varying ambient conditions. Additionally, the study examines the influence of partial cement replacement with GGBS on thermal behaviour, revealing that while GGBS effectively reduces thermal reactions at higher contents, its efficacy diminishes with rising ambient temperatures. [ABSTRACT FROM AUTHOR]

This paper examines the properties of sewage sludge ashes (SSAs) from the incineration of sewage sludge with added limestone for toxic gas treatment. It also evaluates the potential valorization of SSA in cement composites as supplementary cementitious materials (SCMs). The work involves a thorough characterization of four SSAs, including physical, chemical, and mineralogical properties. It also includes assessing the behavior of SSA in water solution through electrical conductivity measurements. The reactivity of ashes was evaluated using the R3 method and mechanical properties. The results revealed that all SSAs present comparable mineralogical and chemical properties, with varying proportions. Major elements such as Ca, Si, Fe, P, and S are predominant in the ashes, with traces of heavy metals. In an aqueous solution, a gradual formation of ettringite was detected only for two SSA. The heavy metal leachability was negligible, confirming that SSA is a non-hazardous waste. Finally, the reactivity and strength activity index assessments revealed a low and slow reactivity of SSA compared to metakaolin or slag. The SSA that favored ettringite formation in aqueous solution presented the lowest compressive strength at 28 days after incorporation in mortar. Despite originating from different incineration sites, these ashes fall under the same category of SCM reactivity. [ABSTRACT FROM AUTHOR]

Introduction. Requirements, applied to materials used for 3D construction printing, can be met by adding modifiers at the stage of designing fine-grained concrete compositions. Natural zeolites can be considered highly effective finely dispersed additives capable of adjusting properties of concrete mixtures, that are particularly relevant for remote development areas having deposits of this mineral raw material.Materials and methods. Research works and experimental data are reviewed to analyze the use of zeolites as a mineral additive in construction. Zeolites can partially, to different extents, replace cement in concrete to optimally meet the requirements of construction 3D printing. The setting time, the density and the dynamic shear stress of various compositions of concrete mixtures, as well as the density, ultimate compressive and bending strength values were determined for mature concrete. Results of strength and calorimetric testing were used to evaluate the activity of zeolite.Results. The best performance was demonstrated by the specimens with 5–15 % zeolite content by the cement weight. The information is provided about the time it takes for the density of concrete mixture to become critical to ensure its suitability for a 3D printer, which is reduced by 60 to 80 minutes for compositions with the 5–15 % zeolite content compared to the controlling composition, provided that and the mixture suitability period can be optimized by choosing the concentration of zeolite. The initial density of the concrete mixture, evaluated using the Vicat cone penetrometer, did not demonstrate any great changes when the share of zeolite was increased.Conclusions. Zeolite improves mechanical characteristics of fine-grained concrete and adjusts the setting time depending on the concentration of the mineral filler. Hence, zeolite can be considered as an effective component of concretes suitable for additive technologies.

Portland cement has a limited shelf life because of the prehydration that can occur during storage. One approach to mitigating strength losses observed for concrete is to pretreat cement with a protective coating to slow the advance of prehydration. This study compared cement pretreatments with alkyl ketene dimer (AKD) wax and a combination of AKD + paraffin wax to a more traditional pretreatment approach using oleic acid. After exposing the treated cements to elevated temperature and humidity conditions, paste and mortar calorimetry tests showed improved resistance to prehydration reactions. The cements aged up to 12 weeks under the accelerated regime showed strength improvement for the mortars made with AKD and AKD + paraffin-treated cements relative to the mortars made with oleic acid-treated cement and mortars made with untreated cement. The wax can be added during clinker milling and additionally functions as a grinding aid.

This research investigates the impact of solution concentration and solution-to-binder ratio (S/B) on the volume changes in alkali-activated slags with sodium hydroxide at 20 °C. Autogenous and thermal strains are monitored with a customized testing device in which thermal variations are controlled. Consequently, both the autogenous strain and coefficient of thermal expansion (CTE) are determined. Heat flow and internal relative humidity (IRH) are also monitored in parallel, making this research a multifaceted study. The magnitudes of autogenous strain and CTE are higher than those of ordinary Portland cement paste. Decreasing the solution concentration or S/B generally decreases the autogenous strain (swelling and shrinkage) and the CTE. The shrinkage amounted to 87 to 1981 µm/m, while the swelling reached between 27 and 295 µm/m and was only present in half of the compositions. The amplitude of the CTE, which increases up to 55 µm/m/°C for some compositions while the CTE of OPC remains between 20 and 25 µm/m/°C, can be explained by the high CTE of the solution in comparison with water. The IRH of paste cannot explain the autogenous strain's development alone. Increasing S/B eliminates the self-desiccation-related decrease. [ABSTRACT FROM AUTHOR]

Aβ peptides are known to bind neural plasma membranes in a process leading to the deposit of Aβ-enriched plaques. These extracellular structures are characteristic of Alzheimer's disease, the major cause of late-age dementia. The mechanisms of Aβ plaque formation and deposition are far from being understood. A vast number of studies in the literature describe the efforts to analyze those mechanisms using a variety of tools. The present review focuses on biophysical studies mostly carried out with model membranes or with computational tools. This review starts by describing basic physical aspects of lipid phases and commonly used model membranes (monolayers and bilayers). This is followed by a discussion of the biophysical techniques applied to these systems, mainly but not exclusively Langmuir monolayers, isothermal calorimetry, density-gradient ultracentrifugation, and molecular dynamics. The Methodological Section is followed by the core of the review, which includes a summary of important results obtained with each technique. The last section is devoted to an overall reflection and an effort to understand Aβ-bilayer binding. Concepts such as Aβ peptide membrane binding, adsorption, and insertion are defined and differentiated. The roles of membrane lipid order, nanodomain formation, and electrostatic forces in Aβ–membrane interaction are separately identified and discussed. [ABSTRACT FROM AUTHOR]

Regulatory cystathionine β-synthase (CBS) domains are widespread in proteins; however, difficulty in structure determination prevents a comprehensive understanding of the underlying regulation mechanism. Tetrameric microbial inorganic pyrophosphatase containing such domains (CBS-PPase) is allosterically inhibited by AMP and ADP and activated by ATP and cell alarmones diadenosine polyphosphates. Each CBS-PPase subunit contains a pair of CBS domains but binds cooperatively to only one molecule of the mono-adenosine derivatives. We used site-directed mutagenesis of Desulfitobacterium hafniense CBS-PPase to identify the key elements determining the direction of the effect (activation or inhibition) and the "half-of-the-sites" ligand binding stoichiometry. Seven amino acid residues were selected in the CBS1 domain, based on the available X-ray structure of the regulatory domains, and substituted by alanine and other residues. The interaction of 11 CBS-PPase variants with the regulating ligands was characterized by activity measurements and isothermal titration calorimetry. Lys100 replacement reversed the effect of ADP from inhibition to activation, whereas Lys95 and Gly118 replacements made ADP an activator at low concentrations but an inhibitor at high concentrations. Replacement of these residues for alanine increased the stoichiometry of mono-adenosine phosphate binding by twofold. These findings identified several key protein residues and suggested a "two non-interacting pairs of interacting regulatory sites" concept in CBS-PPase regulation. [ABSTRACT FROM AUTHOR]

Portland cement has a limited shelf life because of the prehydration that can occur during storage. One approach to mitigating strength losses observed for concrete is to pretreat cement with a protective coating to slow the advance of prehydration. This study compared cement pretreatments with alkyl ketene dimer (AKD) wax and a combination of AKD + paraffin wax to a more traditional pretreatment approach using oleic acid. After exposing the treated cements to elevated temperature and humidity conditions, paste and mortar calorimetry tests showed improved resistance to prehydration reactions. The cements aged up to 12 weeks under the accelerated regime showed strength improvement for the mortars made with AKD and AKD + paraffin-treated cements relative to the mortars made with oleic acid-treated cement and mortars made with untreated cement. The wax can be added during clinker milling and additionally functions as a grinding aid. [ABSTRACT FROM AUTHOR]

Background: Relapse of Candida albicans urinary tract infection (UTI) is frequent despite appropriate treatment, as commonly used antifungals such fluconazole and flucytosine are only fungistatics. To improve treatment of Candida UTI and decrease relapses, understanding the long-term metabolic activity and survival of C. albicans in urine containing antifungals at minimal inhibitory concentration (MIC) is needed. Methods: we monitored the survival, metabolic activity and consumption of glucose and proteins by C. albicans using conventional methods and isothermal microcalorimetry (IMC). We also investigated the influence of dead Candida cells on the growth of their living counterparts. Results: For 33 days, weak activity was observed in samples containing antifungals in which C. albicans growth rate was reduced by 48%, 60% and 88%, and the lag increased to 172 h, 168 h and 6 h for amphotericin, flucytosine and fluconazole, respectively. The metabolic activity peaks corresponded to the plate counts but were delayed compared to the exhaustion of resources. The presence of dead cells promoted growth in artificial urine, increasing growth rate and reducing lag in similar proportions. Conclusions: Even with antifungal treatment, C. albicans relapses are possible. The low metabolic activity of surviving cells leading to regrowth and chlamydospore formation possibly supported by autophagy are likely important factors in relapses. [ABSTRACT FROM AUTHOR]

Repair materials for concrete infrastructure applications are designed to minimize closure time and subsequent effect on traffic. Available material choices are typically limited to expensive prepackaged materials or high-early-strength (HES) concrete mixtures. HES concrete mixtures are often designed with high paste content and limited inclusion of supplementary cementitious materials so to promote higher early-age strengths. The traditional approval for HES concrete mixtures has relied on testing the strength of concrete cylinders cured at room temperature. This practice has often resulted in the overdesign of these HES mixtures, primarily because it fails to consider the higher temperatures that typically develop during the in situ curing. Moreover, as highlighted in several reports by state agencies, the high cement content and the near absence of proper curing practices have likely contributed to the premature failure of some of these mixtures. In this study, isothermal calorimetry was explored as a potential tool to quickly evaluate HES concrete formulations in terms of early-age mechanical performance. It was found that this test method, when combined with maturity, can provide reasonable estimations of the concrete strength development for isothermal and nonisothermal curing conditions up to 8 h after the initial mix. The proposed test method can be used as a first step in the optimization of HES concrete mixtures and can help predicting the time to reopening for in situ conditions. [ABSTRACT FROM AUTHOR]

Using solid waste-based materials, such as recycled building aggregate (RCA), preparing 3D-printed materials can reduce costs but increase the water–cement ratio of the printed material, which reduces its mechanical performance. In order to solve the problem of mechanical properties decline caused by an increase in the w/c ratio, this experiment found that adding calcined salt mud (CSM) to the printing materials and changing the water-to-cement ratio from 0.37 to 0.4 CSM can ensure that the compressive strength of the printing materials remains basically unchanged. Moreover, through TG, SEM, and other microscopic data, it can be seen that calcium hydroxide in CSM can not only participate in the synergistic reaction of ethylene/vinyl acetate copolymer (EVA) and dust ash (DA), produce more NaOH, and promote the hydration of granulated blast furnace slag (GBFS) but also promote the formation of ettringite together with SO42− in solution, optimizing pore size distribution.

The amyloidogenic Aβ peptides are widely considered as a pathogenic agent in Alzheimer's disease. Aβ(1-42) would form aggregates of amyloid fibrils on the neuron plasma membranes, thus perturbing neuronal functionality. Conflicting data are available on the influence of bilayer order on Aβ(1-42) binding to membranes. In the present study, a biophysical approach was used in which isothermal calorimetry and surface pressure measurements were applied to explore the interaction of Aβ(1-42) in either monomeric, oligomeric, or fibrillar form with model membranes (bilayers or monolayers) in the liquid-ordered state that were either electrically neutral or negatively charged. In the latter case, this contained phosphatidic acid, cardiolipin, or ganglioside. The calorimetric studies showed that Aβ(1-42) fibrils, oligomers, and monomers could bind and/or be inserted into bilayers, irrespective of electric charge, in the liquid-ordered state, except that monomers could not interact with electrically neutral bilayers. The monolayer studies in the Langmuir balance demonstrated that Aβ(1-42) aggregation hindered peptide insertion into the monolayer, hindered insertion in the decreasing order of monomer > oligomer > fibril, and that lipid composition did not cause large differences in insertion, apart from a slight facilitation of monomer and oligomer insertion by gangliosides. [ABSTRACT FROM AUTHOR]

This study investigates the suitability of heat conduction calorimeters for determining the specific heat capacity of solid and liquid substances. Accurate and precise measurements were obtained for various substances, including water, ethylene glycol, the ionic liquid [EMIM][TCM], and copper, with relative standard deviations averaging less than 1%. Measurements on [EMIM][DCA] indicated a systematic deviation from the literature values. The study highlights the repeatability of the measurement method, which worked well for both temperature increases and decreases, as well as for the mean of the two. The influence of sample size on the results when it came to liquids was also investigated, revealing that large sample sizes led to underpredictions; while, small sizes yielded the opposite effect. The best results were obtained with half-filled vials; a similar filling level as was used in the electrical calibrations of the calorimeters with heaters in the vials. Additionally, no significant differences were observed among the eight calorimeters of the I-Cal Flex instrument, and different baseline calculation methods had negligible impact on the results. Overall, this study illustrates how a heat conduction calorimeter can be utilized for accurate and precise heat capacity measurements for both solid and liquid substances. [ABSTRACT FROM AUTHOR]

The durability of mass concrete structures may be compromised due to stresses and cracking induced by temperature rise due to cement hydration and concrete’s insulating capacity. Delayed ettringite formation and thermal cracking may occur when maximum temperatures and maximum temperature differences are greater than the allowable limits. Through a real-world case study in Douglasville, Georgia, this work investigates how modeling, construction decisions, and thermal limits influence the construction decisions of a mass concrete footing and abutment wall. Thermal control measures deemed necessary to satisfy thermal limit criteria for the abutment wall construction included precooling the concrete using liquid nitrogen and post-cooling the abutment wall using internal cooling pipes. Both measures, however, increased the cost and complexity of construction. The footing also required pre-cooling of the concrete even though it was not classified as mass concrete. In this work, the temperature development of the footing and the wall is modeled through a progressive approach based on laboratory-scale isothermal calorimetry. Based on the modeling, alternative design and construction options to satisfy thermal limits imposed by several Department of Transportation (DOT) guidelines, but at lower cost and complexity, are considered. A performance-based temperature difference limit (PBTDL) that considers a certain project’s mechanical performance and material properties is introduced as an alternative to the current difference limit prescribed by DOTs, which in certain cases can be inflexible, overly conservative, and overly simplified. The analysis also investigates the geometric hard limit specified by certain DOTs to classify mass concrete. The investigation shows that the cost and complexity of mass concrete construction can be significantly reduced with progressive modeling, performance-based decision-making, and a holistic outlook on the mass concrete problem.

This study aims to develop an ambient-cured nano-engineered one-part alkali-activated materials with excellent thermal characteristics using graphene nanoplatelets (GNPs) and ternary precursors. Their compressive strength, thermal properties, microstructure, pore structure were characterised through visual observation, isothermal calorimetry, TGA, XRD, SEM/EDS and X-ray μCT after high temperature exposure to 200–800 °C. The research findings indicated high strength characteristics of the developed AAM (∼80 MPa) at ambient condition, which could further reach to approx. 100 MPa after being heated up to 400 °C. GNPs provided nucleation effects for promoting geopolymerisation and crystallisation. As observed from X-ray CT, a high extent of severe cracks initiated from the core and propagated towards the surface. From SEM/EDS analysis, high Na/Al and Na/Si ratios or low Si/Al and Ca/Si ratios highly correlated to thermal stability. Overall, the research outcomes implied the promising use of the nano-engineered AAMs for thermal energy storage (TES) at 400 °C.

This study examines the impact of particle size on the setting behavior of tricalcium silicate powders. The setting behavior was evaluated using ISO 6876 indentation testing and isothermal induction calorimetry techniques. The objective was to compare the outcomes obtained from these methods and establish a correlation between particle size and setting characteristics. The cement pastes were manually mixed with a water-to-solid ratio of 0.66 for conducting indentation tests according to ISO 6876, while calorimetry measurements were performed using isothermal (conduction) calorimetry at room temperature. The findings demonstrate a significant influence of smaller particle sizes on accelerating the hydration process of cement pastes, resulting in a reduction of setting time by up to 24%. Moreover, the final setting times obtained through the indentation method closely approximate the inflection points of the acceleration curves acquired by calorimetry, with time deviations of less than 12% regardless of particle size. [ABSTRACT FROM AUTHOR]

Cementitious materials can be treated with organosilicon compounds (silanes) to achieve a water‐repellent effect. However, the influence of silanes on cement hydration is still not fully understood. For this reason, we studied the hydration of the main Portland cement phase (C3S ‐ tricalcium silicate) and the interaction with iBTES (isobutyltriethoxysilane), iOTES (isooctyltriethxysilane) and nOTES (n‐octyltriethoxysilane) by isothermal calorimetry and in‐situ X‐ray diffraction (XRD). The results show that C3S hydration is initially retarded and subsequently accelerated by iBTES and iOTES. In addition to the hydration process, the crystal growth of the portlandites (calcium hydroxide) is also affected by the silanes. The XRD results indicate that the portlandites grow significantly more plate‐like. In this context, the influence of the silanes on the portlandite crystallization was therefore also recorded in a special experimental setup. From the scanning electron microscope images it can be shown that all portlandite crystals grown in the presence of silanes have a platelike morphology. This is due to the fact that the hexagonal surfaces of the portlandite are covered by silanes and thus the growth direction of the crystals is affected. The modified portlandite crystals indicate that silanes also influence the microstructure of the cement paste and therefore its chemical and mechanical properties. [ABSTRACT FROM AUTHOR]

In this study we focus on the development of plastic shrinkage and capillary pore pressure on mortars containing metakaolin and limestone powder as cement replacement. Isothermal calorimetry was also used to compliment the early age properties of the investigated mortars. Strength development and phase assemblage using thermal analysis were also investigated. Five different replacement levels of metakaolin and LSP and two different amounts of SP were used. Our data show that the shrinkage strain values increased as the amount of SCMs increased, while capillary pressure showed a mixed trend. The hydration kinetics did not appear to be influenced much from the SCMs used. Strength development improved in general when metakaolin was used while decreasing when LSP was added, as already expected. The TGA data show an increase in the consumption of portlandite as the amount of SCMs was increased. [ABSTRACT FROM AUTHOR]

Self‐heating during storage of biomass in piles causes material losses, leads to emissions to air, and poses a risk of fire. There are different techniques to assess a biomass material's propensity for self‐heating, some of these are briefly reviewed. One of these techniques is isothermal calorimetry, which measures thermal power from materials and produces time‐resolved curves. A recently developed and published test standard, ISO 20049‐1:2020, describes how the self‐heating of pelletized biofuels can be determined by means of isothermal calorimetry and how thermal power and the total heat produced during the test should be measured by isothermal calorimetry. This paper supports interpretation of the result obtained by isothermal calorimetry; the mentioned standard provides examples of peak thermal power and total heat but does not provide any assistance on how the result from isothermal measurements should be interpreted or how the result from measurements on different samples could be compared. This paper addresses the impact of different types of reactions, peak thermal power, total heat released (heat of reaction), activation energy, heat conductivity, and pile size on the temperature development in a generic pile of biomass. This paper addresses important parameters when the result from isothermal calorimetry is evaluated. The most important parameter, with respect to temperature development in large piles, was found to be the total heat released. It was also proposed that safe storage times, that is, the time until a run‐away of the temperature in the pile, could be ranked based on the time to the peak thermal power. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the heat generated during the hydration process in cementitious composites containing multi-walled carbon nanotubes (MWCNTs). The cumulative heat release and heat flow of these cementitious composites were measured over a period of 168 h using isothermal calorimetry. Three different MWCNT dosages, 0.05 wt%, 0.1 wt%, and 0.2 wt%, along with two different sonication times for the solution, which were 20 min and 60 min, were applied in the experimental program. The results reveal that the incorporation of MWCNTs and the use of a naphthalene-based superplasticizer to disperse the nanotubes generally led to a reduction in heat emission during the early stages of hydration, a lower first peak value in the initial stage of hydration, and a significant delay in the acceleration period compared with the reference sample lacking this superplasticizer. Furthermore, the results demonstrate that both the dosage of multi-walled carbon nanotubes (MWCNTs) and the sonication time have an impact on the heat emission and hydration process since the same amount of superplasticizer was applied to all pastes. An increase in the MWCNT dosage led to a decrease in the rate of hydration heat at the main peak for all pastes. Additionally, longer sonication times resulted in lower values of heat generated, reduced main peak values in the heat rate evolution, and generally extended delays in the occurrence of the main peak. [ABSTRACT FROM AUTHOR]

The influence of Fe 2 O 3 on the hydration kinetics of tricalcium aluminate (C 3 A) was studied in order to clarify the mechanism of improving hydration resistance of CaO by in-situ synthesized tricalcium aluminate. The Krstulovic-Dabic model was used to investigate the hydration processes of Fe 2 O 3 -C 3 A solid solution and calculate the corresponding kinetic parameters. The hydration products were analyzed by the X-ray diffraction and scanning electron microscope. The results indicated that the Krstulovic-Dabic model simulated the hydration processes of Fe 2 O 3 -C 3 A solid solution at different stages effectively. The hydraulic activity of Fe 2 O 3 -C 3 A solid solution decreased with the addition of Fe 2 O 3. Reasonable amount of Fe 2 O 3 addition reduced the hydration rate in the initial stage of Fe 2 O 3 -C 3 A solid solution hydration, while the hydration rate of Fe 2 O 3 -C 3 A solid solution was increased with excessive amount Fe 2 O 3. The hydration process was controlled by multiple mechanisms due to an incomplete layer of hydration products was formed on the surface. [ABSTRACT FROM AUTHOR]

The papain-like protease (PLpro) of SARS-CoV-2 (COVID-19) is a high-profile drug target for treating COVID-19 due to its critical role in making essential proteins crucial in viral replication and host immune sensing. The development of small molecule inhibitors of PLpro is an area of ongoing research and interest. To investigate the development of PLpro inhibitors, a series of novel flavanone derivatives were designed using in silico docking against the papain-like protease of COVID-19. The most promising targets were synthesized and structurally characterized by NMR and mass spectrometry. Using isothermal calorimetry studies, two synthesized derivatives were found to bind PLpro in the low micromolar to nanomolar range.

In the recent century, geopolymer materials have grown significantly due to their unique properties applicable in many different fields. In the present work, the heat evolution, thermal and mechanical behavior of inorganic geopolymer composites (IPCs), based on solid solution of feldspathic minerals (pegmatite and granite) or sand quartz that were altered by a low fraction (15–20 mass%) of calcined clay (metakaolin or calcined halloysite). The isothermal calorimeter tests revealed that the heat flow evolution (dQ/dt) of mix design of different compositions was low compared to standard geopolymer materials due to low reactivity in alkaline medium of solid solution used. It was also found that the integrated heat flow during the geopolymerization decreases with the crystallinity of solid solution. The thermogravimetric analysis of all the samples revealed two main changes, before 120 °C and between 700 and 890 °C. The changes are attributed to the loss of water molecules and crystallization of albite and nepheline, respectively with an overall loss of mass which varies from 14.0 to 21.6%. The heating microscope up to 1200 °C shows a shrinkage of 50% for D3C4 and R2C1 samples. The study of mechanical and physical behaviors of geopolymer composites with different compositions showed that samples based on pegmatite and MK developed higher strengths (42.11 MPa and 106.75 MPa for flexural and compression) associated with lower water absorption (7.01%). The high strengths obtained were due to the combination of denser and homogeneous microstructure of IPCs. These materials are potential candidates for eco-friendly construction materials. [ABSTRACT FROM AUTHOR]

Cement production contributes significantly to carbon dioxide emissions. Alkali-activated materials offer an environmentally friendly alternative due to their comparable strength, durability and low-carbon emissions while utilizing wastes and industrial by-products. Wood ash is a waste material that shows promising results as a partial replacement for Portland cement and precursors in alkali-activated systems. The aim of this study was to examine the effect of ground wood ash on the mechanical properties of alkali-activated mortars. Wood ash was incorporated as a 0 wt%, 10 wt% and 20 wt% partial replacement for ground granulated blast furnace slag (GGBFS). The wood ashes were ground in a planetary ball mill for 10 and 20 min. Sodium silicate (Na2SiO3), sodium carbonate (Na2CO3), and sodium hydroxide (NaOH) were used as alkali activators. The results demonstrated that ground wood ash improved the mechanical properties of alkali-activated systems compared to untreated wood ash. However, the incorporation of wood ash increased the porosity of the binder matrix. [ABSTRACT FROM AUTHOR]

A comprehensive experimental program has been performed to characterize the hydration and engineering property evolution of a class G oil well cement under various curing temperatures from 30 to 90 °C. The progress of hydration was monitored by isothermal calorimetry (atmospheric pressure); the viscosity evolution was measured using a high temperature and high pressure consistometer (up to 200 MPa); the ultrasonic property development was evaluated by an ultrasonic cement analyzer (up to 100 MPa). Test results indicate that the influences of curing temperature and pressure on the hydration, viscosity and ultrasonic property development can be modeled by a scale factor method that is similar to the maturity method used in the concrete industry. However, the key parameters of the scale factor model, namely the apparent activation energy and the apparent activation volume of cement showed obvious variations with test method and curing condition. The test results indicate that the curing temperature has a stronger effect on cement hydration rate than viscosity and ultrasonic property development rate, while the curing pressure has a much stronger influence on cement slurry properties before setting (viscosity) than after setting (ultrasonic property). [ABSTRACT FROM AUTHOR]

Background: HDL possesses anti-inflammatory properties, however, the exact mechanism is not fully understood. Endotoxin is a potent inducers of TLR4 signaling, leading to inflammatory mediators’ release. It has been estimated that TLR4 recognizes about 5% of circulating lipopolysaccharide whereas 95% is cleared by plasma lipoproteins, mainly HDL. ApoM is required for HDL biogenesis and 95% of plasma ApoM is found associated with HDL, both are significantly reduced during sepsis. Aim: The aim of this study is to investigate whether ApoM binds endotoxin and contributes to anti-inflammatory activity of HDL. Methods: Isothermal Titration Calorimetry (ITC) was used to determine the binding of ultrapure E. coli LPS to the recombinant ApoM protein. Purified human HDL and recombinant ApoM was used to investigate LPS neutralization using human and murine macrophages and computational simulation was performed. Result: ApoM shows high affinity for E. coli LPS, forming 1:1 complexes with Kd values below 1 μΜ, as revealed by ITC. The binding process is strongly exothermic and enthalpy-driven (ΔrH = −36.5 kJ/mol), implying the formation of an extensive network of interactions between ApoM and LPS in the bound state. Computational simulation also predicted high-affinity binding between ApoM and E. coli LPS and the best scoring models showed E. coli LPS docking near the calyx of ApoM without blocking the pocket. The biological significance of this interaction was further demonstrated in macrophages where purified HDL neutralized an E. coli LPS effect and significantly reduced TNFα release from human THP-1 cells. Conclusion: ApoM binds LPS to facilitate endotoxin neutralization and clearance by HDL.

Achieving the correct sulfate balance in limestone calcined clay cements (LC3) to control aluminate hydration is critical for early hydration and property development, but the role of the calcined kaolin (metakaolin) fraction relative to other compositional variables has not been previously well-explored. In addition, little published research has investigated the influence of water-to-solid ratio (w/s) and superplasticizers in this context. This study assesses the influence and quantifies the relative significance of compositional predictors on the sulfate balance and cumulative heat evolved by 24 h for LC3 through a stepwise regression model. Sulfate balance was defined as the time difference between the sulfate depletion point and the time of maximum of alite peak obtained from a time derivative of data obtained through isothermal calorimetry. A methodology based on Kernel smoothing was used to precisely identify these events. The first 24 h of hydration of some LC3 pastes was also monitored via in-situ X-ray diffraction to develop linkages between LC3 composition and hydrated phase assemblage. The statistical analysis identified the metakaolin fraction as particularly significant for the sulfate balance. The results suggest that the metakaolin fraction influences the sulfate balance of LC3 both directly and through its interactions with other constituent materials such as limestone.

Partial replacement of ordinary portland cement (OPC) with supplementary cementitious materials (SCMs) is a ubiquitous and effective approach to design concrete mixtures with lower embodied carbon and improved durability compared to plain OPC concrete mixtures. However, the global supply of common industrial SCMs, like fly ash (a byproduct of coal combustion) and blast-furnace slag (a byproduct of steelmaking), is dwindling due to global decarbonization efforts and sustained demand from the concrete industry. The newly standardized ASTM C1897 rapid, relevant, and reliable (R3) test is an effective screening method to measure the chemical reactivity of potential SCMs. However, the sample quantity requirements impede the rapid-throughput screening of new SCM sources that may currently be available only in small quantities. The objective of the current study is to design and validate a small-scale modified R3 test to enable standardized characterization and rapid-throughput screening of novel SCMs. The results substantiate that the ASTM C1897 R3 bound water method can be performed with sufficient accuracy at a much smaller scale (i.e., 0.01 g of SCM per test) using the thermogravimetric method developed and validated herein.

Weakly coordinating anions (WCAs) have attracted much attention in recent years due to their ability to stabilise highly reactive cations. It may well be argued, however, that a profound understanding of what truly defines a WCA is still lacking, and systematic studies to unravel counterion effects are scarce. In this work, we investigate a supramolecular pseudorotaxane formation reaction, subject to a selection of anions, ranging from strongly to weakly coordinating, which not only aids in fostering our knowledge about anion coordination properties, but also provides valuable theoretical insight into the nature of the mechanical bond. We employ state-of-the-art DFT-based methods and tools, combined with isothermal calorimetry and 1 H NMR experiments, to compute anion-dependent Gibbs free association energies Δ G a , as well as to evaluate intermolecular interactions. We find correlations between Δ G a and the anions' solvation energies, which are exploited to calculate physico-chemical reaction parameters in the context of coordinating anions. Furthermore, we show that the binding situation within the (pseudo)rotaxanes can be mostly understood by straight-forward electrostatic considerations. However, quantum-chemical effects such as dispersion and charge-transfer interactions become more and more relevant when WCAs are employed. [ABSTRACT FROM AUTHOR]

Peanut (Arachis hypogaea L.) skins are primarily an industrial by-product with only small quantities utilized in animal feed or dropped directly. Due to peanut skins being a rich source of phenolic compounds with antioxidant activity and low cost, they have a great potential utility as food preservative. Herein, the chemical composition and antioxidant activity of extracts obtained from peanut skins prepared with 95% ethanol by ultrasound extraction also needed to be established. The crude peanut skin extracts of extraction yield, total phenols and flavonoids, DPPH scavenging activity, ferrous-ion chelating activity, reducing power, Trolox equivalent antioxidant capacity (TEAC) and accelerated oxidation of button mushroom (Agaricus bisporus) and sacha inchi (Plukenetia volubilis L.) oil were evaluated. To understand the actual antioxidant effects of peanut skin extracts, the button mushroom and sacha inchi oil were added in various doses of peanut skin extracts under air and pure oxygen ambient with the isothermal temperature of 30 and 60.5 °C by conducting isothermal calorimeter (TAM Air) analyses, respectively. Overall, the peanut skin extracts displayed beneficial antioxidant properties in button mushrooms and sacha inchi oil, which could be used as a natural antioxidant of agricultural waste reduction and added value to circular economy and sustainable development in food industries for SDG12 by responsible consumption and production. [ABSTRACT FROM AUTHOR]

The suitability of the rapid, relevant, and reliable (R3) heat of hydration and bound water tests for measuring the reactivity of various supplementary cementitious materials (SCMs) and their blends with calcium hydroxide (CH) was investigated in this study. These tests have been recently standardized in current standards. The test was carried out on pastes of fly ash (FA), slag (S), kaolinitic calcined clay (K), limestone (LS), and their blends. A detailed analysis of the heat of hydration and bound water measurements specified according to the R3 test was carried out. A good correlation was found between the two types of test results and also between the reactivity test results versus strength activity index measured using cement mortar compressive strength. The formation of hydration products in the R3 test paste specimens was also studied using X-ray diffraction (XRD). The hydration products for SCMs formed in the test were similar to those reported in cement systems. It was seen that the interactions in the blended SCMs with CH were also similar to those reported in cement pastes. Further, the microstructure of the specimen was studied using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis, and the overall hydration of various SCMs was studied. The influence of the proportions of the SCMs in the blended SCMs and that of fineness were also investigated. The applicability and limitations of this test method for SCMs and their blends were discussed. [ABSTRACT FROM AUTHOR]

Oxidative stability and antioxidant properties significantly impact the quality, shelf-life, and nutritional value of food. However, current methods for studying lipid oxidation and antioxidants face limitations including a lack of real-time monitoring, difficulties in complex food matrix assessment, limited sensitivity, and mechanistic insights. Invasive sample preparation and reliance on model systems further compound these challenges. Overcoming these limitations is essential for advancing food preservation and product development strategies. This review discusses the use of isothermal calorimetry (IC) in food science, particularly for studying lipid oxidation and antioxidant properties. It explains how IC heat flow data can provide valuable kinetic information, revealing the mechanisms of antioxidant action. Moreover, the review evaluates the advantages and limitations of IC in food science, providing insights into its potential for future research and applications. IC enables real-time monitoring of lipid oxidation and antioxidant activity, offering valuable insights into their behavior in the presence of food-based oxidizable substrates. By measuring heat flow over time and applying appropriate data analysis, IC can generate key kinetic parameters that describe the rates of oxidation and the rate constants of both oxidation and inhibition reactions. Additionally, kinetic modeling allows for the assessment of antioxidant efficiency (A.E.) and oxidizability index (O.I.), which are especially useful for complex food matrices such as emulsions, encapsulated powders, and natural extracts. While IC provides direct measurement, high sensitivity, and long-term thermal stability, challenges include the non-specificity of heat flow and the requirement for specialized expertise to set up and interpret experiments accurately. [Display omitted] • Isothermal calorimetry proves to be a reliable technique to study lipid oxidation. • Isothermal calorimetry data provides valuable kinetic information revealing the mechanisms of oxidation reactions. • Kinetic modeling of isothermal calorimetry data allows for the assessment of antioxidant efficiency and oxidizability index. [ABSTRACT FROM AUTHOR]