Isothermal Step Research Articles

Analyzing the Debinding Step of Ti64 Parts Fabricated by 3D Printing Extrusion

The aim of this work is to analyze the effect of the heating rate used during the debinding step on the consolidation of parts fabricated by additive manufacturing using the 3D printing extrusion of Ti64 samples. The cylindrical samples print by extruding MIM pellets of Ti64 mixed with a binder. Dilatometry tests follow the densification of the samples by using three different heating rates during the heating stage. All the samples then undergo the same thermal cycle of sintering. SEM and XRD analyze the microstructure. Microhardness and compression tests evaluate the mechanical properties of the sintered samples. We analyze the corrosion behavior under Hank’s solution. The results indicated that the heating rate used during the debinding step affects the densification by reducing this as the heating rate increases. After sintering, a lower relative density is reached, resulting in decreased mechanical properties and corrosion resistance. The Young’s modulus and yield strength correspond well with those of the Ti64 samples prepared by other techniques with similar porosities. Despite the remaining porosity, the parts fabricated by SLM had worse corrosion behavior than ours. The main conclusion is that the isothermal step during debinding is not necessary to ensure complete binder elimination, which will reduce the process time and thus, the fabrication costs of parts by this technique.

One-Step Molten-Salt-Assisted Approach for Direct Preparation and Regeneration of LiNi0.6Co0.2Mn0.2O2 Cathode.

Single-crystal lithium-nickel-manganese-cobalt-oxide (SC-NMC) is attracting increasing attention due to its excellent structural stability. However, its practical production faces challenges associated with complex precursor preparation processes and severe lithium-nickel cation mixing at high temperatures, which restricts its widespread application. Here, a molten-salt-assisted method is proposed using low-melting-point carbonates. This method obviates the necessity for precursor processes and simplified the synthetic procedure for SC-NMC down to a single isothermal sintering step. Multiple characterizations indicate that the acquired SC-LiNi0.6Mn0.2Co0.2O2 (SC-622) exhibits favorable structural capability against intra-granular fracture and suppressive Li+/Ni2+ cation mixing. Consequently, the SC-622 exhibits superior electrochemical performance with a high initial specific capacity (174 mAhg-1 at 0.1C, 3.0-4.3V) and excellent capacity retention (87.5% after 300 cycles at 1C). Moreover, this molten-salt-assisted method exhibits its effectiveness in directly regenerating SC-622 from spent NMC materials. The recovered material delivered a capacity of 125.4 mAhg-1 and retained 99.4% of the initial capacity after 250 cycles at 1 C. This work highlights the importance of understanding the process-structure-property relationships and can broadly guide the synthesis of other SC Ni-rich cathode materials.

Optimizing Size and Number Density of Al3Zr Dispersoids in Al–Zn–Mg–Cu Alloys

The formation and temporal evolution of Al3Zr dispersoids in an Al–Zn–Mg–Cu alloy is investigated by in situ small‐angle X‐ray scattering during different homogenization treatments. The aim is to determine the most effective homogenization parameters for obtaining a high number density and small size of the dispersoids. Nucleation of the dispersoids is found to start above 400 °C and is boosted after isothermal holding at 425 °C. Regardless of the detailed homogenization profile, coarsening of the dispersoids is not observed below 450 °C. The results demonstrate that decreasing the heating rate, prolonging the first isothermal step, or increasing the number of steps are all beneficial regarding an increase of both, the volume fraction, and the number density of the dispersoids. Among the four investigated homogenization profiles, the one with decreasing the heating rate shows the highest impact.

Harnessing Viscoelasticity to Suppress Irreversibility Buildup in a Colloidal Stirling Engine.

Typically, the rate at which a heat engine can produce useful work is constrained by the buildup of irreversibility with increasing operating speed. Here, using a recently developed reservoir engineering technique, we designed and quantified the performance of a colloidal Stirling engine operating in a viscoelastic bath. While the bath acts like a viscous fluid in the quasistatic limit, and the engine's performance agrees with equilibrium predictions, on reducing the cycle time to the bath's structural relaxation time, the increasingly elastic response of the bath aids suppress the buildup of irreversibility. We show that the elastic energy stored during the isothermal compression step of the Stirling cycle facilitates quick equilibration in the isothermal expansion step. This results in equilibriumlike efficiencies even for cycle times shorter than the equilibration time of the colloidal particle.

Exploring 4D microstructural evolution in a heavily deformed ferritic alloy

We present a multi-scale study of recrystallization annealing of an 85% cold rolled Fe-3%Si alloy using a combination of dark field X-ray microscopy (DFXM), synchrotron X-ray diffraction (SXRD), and electron backscatter diffraction (EBSD). The intra-granular structure of the as-deformed grain reveals deformation bands separated by ≈ 3–5°misorientation. We monitor the structural evolution of a recrystallized grain embedded in bulk, from the early stages of recrystallization to 65% overall recrystallization through isothermal annealing steps. Results show that the recrystallized grain of interest (GOI) grows much faster than its surroundings yet remains constant in size as the recrystallization proceeds. Isolated dislocations embedded within the volume of the recrystallized GOI are investigated.

Synthesis, protection performance, and failure analysis of α-Al2O3/Mo(Si,Al)2 coatings

To prepare the advanced cooling structure of hollow turbine blades, molybdenum metal core (MMC) has been proposed as a substitute for ceramic core substrate, but the protective coating needs to be redesigned to resist ablation during the shell burning process and erosion during the casting process. To this end, in this study, an α-Al2O3/Mo(Si,Al)2 barrier coating is fabricated on a molybdenum surface utilizing a two-step pack cementation process, which includes first siliconizing and then aluminizing, combined with pre-oxidation treatments. The pre-oxidation behavior of the new Mo(Si,Al)2 coating under isothermal oxidation (at 1300 °C) and step oxidation and its protection performance during the superalloy casting process are comprehensively examined. The results indicate that the as-deposited coating consists of an outer Mo(Si,Al)2 layer and an inner Al8Mo3 layer. After pre-oxidation, an admixture (SiO2▪Al2O3) monolayer is first formed on the surface of MMC. Then, internal Al2O3 emerges in the lower part of (SiO2▪Al2O3) mixture. Finally, the SiO2 → Al2O3 displacement reaction encapsulates MMC with an exclusive α-Al2O3 layer. Besides, the step oxidation process can obviously enhance the formation of external α-Al2O3 compared to the isothermal oxidation process. Unfortunately, after pre-oxidation treatment, a bulge arises at the interface of Mo(Si,Al)2 and Al8Mo3. The buckled coating induces partially destruction of the MMC coating by the alloy melt, whereas the intact coating can protect MMC during the casting process. Furthermore, the interfacial gap of MMC varies with the addition of alumina.

Nucleic Acid Detection through RNA-Guided Protease Activity in Type III-E CRISPR-Cas Systems.

RNA-guided protease activity was recently discovered in the type III-E CRISPR-Cas systems (Craspase), providing a novel platform for engineering a protein probe instead of the commonly used nucleic acid probe in nucleic acid detection assays. Here, by adapting a fluorescence readout technique using the affinity- and fluorescent protein dual-tagged Csx30 protein substrate, we have established an assay monitoring Csx30 cleavage by target ssRNA-activated Craspase. Four Craspase-based nucleic acid detection systems for genes from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), norovirus, and the influenza virus (IFV) were reconstituted with demonstrated specificity. The assay could reliably detect target ssRNAs at concentrations down to 25 pM, which could be further improved approximately 15 000-fold (ca. 2 fM) by incorporating a recombinase polymerase isothermal preamplification step. Importantly, the species-specific substrate cleavage specificity of Craspase enabled multiplexed diagnosis, as demonstrated by the reconstituted composite systems for simultaneous detection of two genes from the same virus (SARS-CoV-2, spike and nsp12) or two types of viruses (SARS-CoV-2 and IFV). The assay could be further expanded by diversifying the fluorescent tags in the substrate and including Craspase systems from various species, thus potentially providing an easily adaptable platform for clinical diagnosis.

Fabrication and Optimization of 3D-Printed Silica Scaffolds for Neural Precursor Cell Cultivation.

The latest developments in tissue engineering scaffolds have sparked a growing interest in the creation of controlled 3D cellular structures that emulate the intricate biophysical and biochemical elements found within versatile in vivo microenvironments. The objective of this study was to 3D-print a monolithic silica scaffold specifically designed for the cultivation of neural precursor cells. Initially, a preliminary investigation was conducted to identify the critical parameters pertaining to calcination. This investigation aimed to produce sturdy and uniform scaffolds with a minimal wall-thickness of 0.5 mm in order to mitigate the formation of cracks. Four cubic specimens, with different wall-thicknesses of 0.5, 1, 2, and 4 mm, were 3D-printed and subjected to two distinct calcination profiles. Thermogravimetric analysis was employed to examine the freshly printed material, revealing critical temperatures associated with increased mass loss. Isothermal steps were subsequently introduced to facilitate controlled phase transitions and reduce crack formation even at the minimum wall thickness of 0.5 mm. The optimized structure stability was obtained for the slow calcination profile (160 min) then the fast calcination profile (60 min) for temperatures up to 900 °C. In situ X-ray diffraction analysis was also employed to assess the crystal phases of the silicate based material throughout various temperature profiles up to 1200 °C, while scanning electron microscopy was utilized to observe micro-scale crack formation. Then, ceramic scaffolds were 3D-printed, adopting a hexagonal and spherical channel structures with channel opening of 2 mm, and subsequently calcined using the optimized slow profile. Finally, the scaffolds were evaluated in terms of biocompatibility, cell proliferation, and differentiation using neural precursor cells (NPCs). These experiments indicated proliferation of NPCs (for 13 days) and differentiation into neurons which remained viable (up to 50 days in culture). In parallel, functionality was verified by expression of pre- (SYN1) and post-synaptic (GRIP1) markers, suggesting that 3D-printed scaffolds are a promising system for biotechnological applications using NPCs.

Characterisation of micro polymer inclusion beads by thermogravimetric analysis

In this study micro polymer inclusion beads (μPIBs), containing di-(2-ethylhexyl)phosphoric acid (D2EHPA) as the extractant and poly(vinyl chloride) (PVC) or poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) as the base polymer, were characterised by thermogravimetric analysis (TGA) for the first time and their extraction performance for La3+ was assessed. μPIBs are a novel polymer-based extracting material fabricated via a recently developed phase inversion microfluidic method. However, since the μPIBs are formed under aqueous conditions and D2EHPA can be slightly water soluble at pH values higher than its pKa of 2.8, the final composition could differ from the theoretical one because of D2EHPA leaching during fabrication. Hence, a TGA method was developed to determine the exact composition of μPIBs, using polymer inclusion membranes (PIMs) of known composition as reference materials. For μPIBs and PIMs containing PVDF-HFP as the base polymer, a linear temperature ramp of 10 °C min−1 was applied and the mass loss of D2EHPA and PVDF-HFP was observed at temperatures up to 270 and 400 °C, respectively. PVDF-HFP-based μPIBs fabricated to theoretically incorporate 40, 50 and 60 wt% D2EHPA were found to contain 40.2, 48.9, and 59.6% of D2EHPA, respectively. In the case of PVC-based μPIBs and PIMs, an isothermal step at 220 °C held for 35 min was required to separate the degradation features of D2EHPA and PVC. PVC-based μPIBs with intended D2EHPA concentrations of 40, 50 and 60 wt% were determined to contain 41.4, 49.6, and 60.8% D2EHPA, respectively. Thus, the TGA degradation profiles indicated that PVC- or PVDF-HFP-based μPIBs underwent negligible D2EHPA leaching during fabrication. TGA studies involving the PVC-based μPIBs revealed that Na+, extracted by D2EHPA during the fabrication process, slowed the thermal degradation of D2EHPA at 220 °C and this affected the accuracy of the composition assessment. Moreover, the presence of Na+ in both PVC- and PVDF-HFP-based μPIBs was found to have a negative impact on the extraction of La3+ which could be overcome by washing the μPIBs with 1 M sulfuric acid after fabrication to remove the Na+.

Complementary use of thermogravimetric analysis and oven to assess the composition and bound CO2 content of recycled concrete aggregates

The carbonation of recycled concrete aggregates (RCA) has emerged as a possible significant carbon sink to mitigate the increase of CO2 concentration in atmosphere and global warming. A reliable determination of bound CO2 content is thus needed to optimize carbonation processes but there is no real consensus on the existing quantification methods, mainly based on thermal decomposition of calcium carbonate. With the aim of developing a relevant quantification method of bound CO2 during the carbonation of RCA, an experimental study based on the combination of two main techniques – thermogravimetric analysis (TGA) and high-temperature oven – was performed at different scales: paste, mortar, and concrete. XRD analyses allowed highlighting the overlaps between the decomposition of portlandite and calcium carbonate polymorphs during linearly increasing temperatures. Oven and TGA with isothermal steps were found to provide consistent and complementary data on RCA composition and their bound CO2 content from initially dried specimens.

Application of distributed activation energy model to predict hydrothermal carbonization kinetics of lignocellulosic biomass

Hydrothermal carbonization (HTC) has been established as one of the most promising techniques for producing biofuels from high moisture containing organic samples such as, biomass. However, limited progress is observed in terms of the kinetic modeling of this process. Existing kinetic models involve mechanistic and experimental shortcomings due to the nature of the non-isothermal and isothermal subsequent steps involved in the process. To address these limitations, a distributed activation energy model (DAEM) was applied to predict HTC kinetics of lignocellulosic biomass. The DAEM considered the non-isothermal temperature profile of the reactor to account for the considerable devolatilization taking place during the transient step of heating. A micro-kinetic reactor was fabricated to facilitate kinetic experiments to estimate the DAEM parameters- mean activation energy, standard deviation, and pre-exponential factor. These parameters were found to be 96.03 kJ mol−1, 3 kJ mol−1, and 5 × 108s − 1 respectively, based on experiments at final HTC temperatures of 190 °C and 210 °C for lignocellulosic biomass. Furthermore, the parameters were used to accurately predict HTC kinetics at 230 °C using the estimated parameters at 190 °C and 210 °C. The obtained results would be valuable inputs for reactor design and large-scale simulations for HTC of lignocellulosic biomass.

Material processing conditions effect on the thermokinetics of end of life tyres

ABSTRACT In this work, end of life tyres (ELTs) samples were subjected to pyrolysis in a dynamic thermogravimetry set-up under various heating rates between 5°C and 25°C min−1. The experimental design involved dried and non-dried sample results in an isothermal step within the heating program, to be able to compare the data against non-dried samples, to further investigate the effect of drying on the results obtained. The drying of the samples resulted in an increase in the onset temperature by some 30°C. However, cryomilling the ELTs samples showed a great effect in reducing the onset of the degradation curve by about 10°C amongst the same set of experiments. The type of sample, in terms of size and processing/milling condition, had a significant impact on the heat flow properties and calorimetry reported. The exothermic region for the original shavings resulted in an enthalpy of −48 J g−1, whilst the cutting mill samples exhibited an enthalpy increase to −184 J g−1. However, the cryomilled samples showed an enthalpy increase estimated at 139 J g−1.

Recent applications of the Successive Self-nucleation and Annealing thermal fractionation technique

Successive Self-nucleation and Annealing (SSA) is a thermal fractionation technique that is performed by Differential Scanning Calorimetry (DSC). The combination of non-isothermal and isothermal steps applied during SSA achieves efficient molecular segregation during polymer crystallization. Such molecular segregation magnifies the effect of defects in polymer chain crystallization, thereby providing information on chain structure. The technique was created and implemented by Müller and co-workers in 1997, becoming a powerful resource for studying ethylene/α-olefin copolymers. The different variables to design the SSA protocol: fractionation window, fractionation time, scanning rate, sample mass, and the first self-nucleation temperature to be applied (Ts, ideal), have been previously reviewed, together with the different applications of SSA. SSA versatility, simplicity (when properly applied), and short times to produce results have allowed its use to study novel and more complex polymeric systems. This review article explores the most recent applications of SSA of the past decade. First, the principles of the technique are briefly explained, covering all the relevant variables. Next, we have selected different cases that show how SSA is employed in various novel fields, such as studying intermolecular interactions and topological effects in homopolymers; supernucleation and antinucleation effects in nanocomposites, including the pre-freezing phenomenon; crystallization modes in random copolymers; solid-solid transitions; miscibility, co-crystallization and composition in blends; evaluation of polymer synthesis variables; and the novel information that could be gained by using fast scanning chip-based calorimetry. Finally, we offer a perspective on SSA, a technique that has become a powerful method for studying the distribution of defects affecting crystallization in semi-crystalline polymers.

Effect of adding CsI on properties of Ge20Sb10Se65Te5 glass

The mechanical and thermal properties of (100-x)Ge20Sb10Se65Te5-xCsI(x = 0, 1, 2, 3, 4) glass was studied. It is found that with increase of CsI, the short-wave cut-off wavelength of infrared transmittance moves from 1000 nm to 900 nm, and the long-wave cut-off wavelength reaches 20 μm. The glass transition temperature decreases from 531 K to 521 K. The crystallization peak temperature Tp decreases from 709 K to 670 K. The Vicker′s hardness decreases from 142HV to 134HV. The fracture toughness increases from o.48 to 0.57. The specific heat capacities were measured by the isothermal step method and it shows that the specific heat for the sample with CsI is larger than that without CsI. For 96Ge20Sb10Se65Te5-4CsI glass, the transmittance changes from 70 % to 53 % if the treatment temperature is between 280 °C and 310 °C. When it is kept at 310 °C for 40 h, the Vicker′s hardness and fracture toughness of the glass can reach 160.56 kgf⋅mm−2 and 0.82 kgf⋅mm−1/2, respectively.

Diagnostics of COVID-19 Based on CRISPR-Cas Coupled to Isothermal Amplification: A Comparative Analysis and Update.

The emergence of the COVID-19 pandemic prompted fast development of novel diagnostic methods of the etiologic virus SARS-CoV-2. Methods based on CRISPR–Cas systems have been particularly promising because they can achieve a similar sensitivity and specificity to the benchmark RT-qPCR, especially when coupled to an isothermal pre-amplification step. Furthermore, they have also solved inherent limitations of RT-qPCR that impede its decentralized use and deployment in the field, such as the need for expensive equipment, high cost per reaction, and delivery of results in hours, among others. In this review, we evaluate publicly available methods to detect SARS-CoV-2 that are based on CRISPR–Cas and isothermal amplification. We critically analyze the steps required to obtain a successful result from clinical samples and pinpoint key experimental conditions and parameters that could be optimized or modified to improve clinical and analytical outputs. The COVID outbreak has propelled intensive research in a short time, which is paving the way to develop effective and very promising CRISPR–Cas systems for the precise detection of SARS-CoV-2. This review could also serve as an introductory guide to new labs delving into this technology.

Microwave-Assisted Water Extraction of Aspen (Populus tremula) and Pine (Pinus sylvestris L.) Barks as a Tool for Their Valorization.

The barks of aspen (Populus tremula) and pine (Pinus sylvestris) are byproducts of wood processing, characterized by their low economic value. In the present study, microwave-assisted one-cycle water extraction was explored as a tool for the valorization of this biomass as a source of biologically active compounds. The microwave extractor of the original construction equipped with a pressurized extraction chamber and a condenser section was used. The microwave-assisted extraction (MAE), specially including dynamic dielectric heating up to 70 °C followed by 30 min of isothermal heating, promoted the isolation of salicin from aspen bark, allowing for the obtention of a two-times-higher free salicin concentration in water extracts (−14% vs. 7%) reached by multi-cycle accelerated solvent extraction (ASE), which is an advanced technique used as a reference. The MAE of pine bark with dynamic heating up to 90–130 °C, avoiding the isothermal heating step, allowed for the obtention of a 1.7-times-higher concentration of proantocyanidin dimers-tetramers, a 1.3-times-higher concentration of catechin and a 1.2-times-higher concentration of quinic acid in water extracts in comparison to a more time- and solvent-consuming ASE performed at the same temperature. The biological activity of the obtained extracts was characterized in terms of their ability to inhibit xahntine oxidase enzyme, which is a validated target for the therapeutic treatment of hyperuricemia.

Advantages of MW-assisted water extraction, combined with steam explosion, of black alder bark in terms of isolating valuable compounds and energy efficiency

“Green” extraction of black alder bark using deionized water as an alternative to organic solvents and microwave (MW) - induced heating instead of convective/conductive heating was studied. An extractor of original construction with the MW capacity of 2.4 kW, equipped with a pressurized extraction chamber (V = 1350 cm3) and a condenser section, was used. The MW-assisted heating of the suspension up to the desirable temperature was performed with a uniform high rate of ~ 30 ℃ min−1. The yield of the black alder bark water extracts obtained by MW-assisted extraction varied from 15.4% to 26.4% (on bark dry matter) increasing with increasing extraction temperature (70–150 ℃) and increasing duration of the isothermal step of extraction (0–30 min). The electricity consumption per dry weight of obtained products needed for MW-assisted heating of the substrate containing suspension varied from 6.2 to 32.0 kWh kg−1 being higher at higher extraction temperature and longer duration of isothermal heating step. UHPLC-ESI-MS/MS, GC-FID, Py-GS/MS/FID, UV spectroscopy methods revealed that the main constituents of the obtained black alder bark water extracts were diarylheptanoids, condensed tannins, carbohydrates, organic acids, flavonoids, lignin related phenols. The MW-induced depolymerization of alder bark cell wall constituents (hemicellulose, lignin) evidenced by Py-GC/MS/FID, GC-FID, wet chemistry analyses of extracts and bark residues after extraction, resulted in the disruption of the bark cell wall and isolation of metabolites bound within it by microwaves-assisted extraction (MAE). Therefore, the black alder bark water extracts, obtained by MAE at 70–110 ℃, compared to those isolated by advanced accelerated solvent extraction (ASE) at a given temperature, have higher diversity and higher contents of different groups of phenolic extractives, including a higher content of their major class in alders – diarylheptanoids. The increase of the extraction temperature above 110 ℃ and the duration of extraction up to 30 min led to an increase of the content of carbohydrates and noticeable decrease of phenolics content in extracts, including the dominating diarylheptanoid - oregonin. The content of oregonin, having a high antioxidant activity and valuable biological activities, was in focus of our research and practical interest. MAE with dynamic heating to 90 ℃ without keeping of isothermal heating is the most attractive for obtaining of oregonin-enriched extracts, containing up to 57% of oregonin, in contrast to ASE water extracts with the maximum oregonin content of 39%. In this regime, two-fold less energy consumption (7 vs 15 kWh kg−1) and two and a half times more productivity (1.5 vs 0.6)% min−1 was achieved in comparison to the case of the ASE method used as reference.

High-Strength Liquid Crystal Polymer-Graphene Oxide Nanocomposites from Water.

We report on the morphology and mechanical properties of nanocomposite films derived from aqueous, hybrid liquid crystalline mixtures of rodlike aggregates of a sulfonated, all-aromatic polyamide, poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT), and graphene oxide (GO) platelets. An isothermal step at 200 °C facilitates in situ partial thermal reduction of GO to reduced GO (rGO) in nanocomposite films. X-ray scattering studies reveal that PBDT-rGO nanocomposites exhibit both higher in-plane alignment of PBDT (the order parameter increases from 0.79 to 0.9 at 1.8 vol % rGO) and alignment along the casting direction (from 0.1 to 0.6 at 1.8 vol % rGO). From dynamic mechanical thermal analysis, the interaction between PBDT and rGO causes the β-relaxation activation energy for PBDT to increase with rGO concentration. Modulus mapping of nanocomposites using atomic force microscopy demonstrates enhanced local stiffness, indicating reinforcement. From stress-strain analysis, the average Young's modulus increases from 16 to 37 GPa at 1.8 vol % rGO and the average tensile strength increases from 210 to 640 MPa. Despite polymer alignment along the casting direction, an average transverse tensile strength of 230 MPa is obtained.

4D microstructural evolution in a heavily deformed ferritic alloy: A new perspective in recrystallisation studies

We present a multiscale study on the recovery and recrystallisation of a heavily deformed (85% reduction in size) Fe–Si–Sn alloy using a combination of dark field X-ray microscopy (DFXM), synchrotron X-ray diffraction (SXRD) and electron backscatter diffraction (EBSD). By utilizing DFXM, we focus on a grain within the high stored energy (HSE) regions, and track it through consecutive isothermal annealing steps. The intra-granular structure of the as-deformed grain reveals deformation bands separated by ≈3–5∘ misorientation. During the early stages of annealing, cells with 2–5∘ misorientation form while new nuclei appear. The recrystallized grains nucleate near prior grain boundaries, having a typical internal angular spread of <0.05∘. The SXRD results suggest no significant macroscopic texture change after annealing for 1400s at 610∘C in the HSE regions. All results indicate that higher misorientation zones such as grain boundaries or junction points of deformation bands are preferential nucleation regions.

Step-scan differential calorimetry of protein denaturation: Modeling and experiment

Calorimetric step-scan curves of the reversible protein denaturation were modeled numerically. The quasi-equilibrium denaturation regime can be realized if the duration of isothermal steps is long enough so that the system is able to settle to equilibrium. We show the changes in the real and imaginary parts of the complex heat capacity during the denaturation process depending on the kinetic regime of denaturation. The practical application of the step-scan method for denaturation of lysozyme in water has revealed the negative temperature coefficient of the excess heat capacity of lysozyme. In the case of denaturation of lysozyme in glycerol studied by fast scanning calorimetry, the step-scan technique can be used to improve the quality of the baseline and reveal a heat capacity step after during denaturation.