Controlled Heat Treatment Research Articles

Investigation of the antioxidant capacity of caramels: Combination of laboratory assays and C. elegans model

Abstract Caramel is one of the most current additive/ingredient obtained by controlled heat treatment of carbohydrates. A combination of in vitro and in vivo methods showed that aromatic caramels and caramel colours are antioxidant. The highest value is obtained for Class III caramel colours for in vitro TEAC and KRL tests (401 µmol Trolox equivalent/g and 5 366 mg gallic acid equivalent/100 g, respectively). In in vivo test, caramels also increase the resistance of C. elegans to oxidant attack, with until 40% live worms after 18 h of treatment in the presence of caramels against no live worms after 12 h of treatment without. In conclusion, this study explore benefit effect of caramels and showed an antioxidant activity linked to their color intensity. The molecules involved remain to be explored.

Evidence for pore water composition controlling carbonate morphology in concrete and the further effect of gamma radiation

Radiation, heat and carbonation can all affect the performance of concrete structures. This study applies either a1.5 MGy gamma radiation dose or thermal treatment at 60°C, followed by an accelerated carbonation period. In comparison to a control sample, irradiation and heat treatment lead to an increase in the carbonation depth which correlates with an increase in crack depth induced by restrained drying-induced shrinkage. When compared to thermally treated samples, there is greater variability in the crack depth of irradiated samples which we ascribe to a radiation-induced change in the mechanical properties of the cement paste. X-ray diffraction is used to identify the calcium carbonate polymorphs that form as result of carbonation. The dominant phase in the control sample is vaterite whereas the dominant phase in both the irradiated and thermally treated samples is calcite. Gamma irradiation leads to a greater calcite:vaterite ratio than thermal treatment. The sequential application of gamma radiation/heat treatment followed by a carbonation period rules out radiolytically producedalcium peroxide octahydrate as the cause of the polymorph switch as it is too short-lived. A new mechanism is hypothesised, where elemental substitution into the calcium carbonate lattice results in deformation and so alters the morphology of the calcium carbonate, leading to the formation of a different polymorph.

Phosphorization Engineering on Metal-Organic Frameworks for Quasi-Solid-State Asymmetry Supercapacitors.

Porous carbon and metal oxides/sulfides prepared by using metal-organic frameworks (MOFs) as the precursors have been widely applied to the realm of supercapacitors. However, employing MOF-derived metal phosphides as positive and negative electrode materials for supercapacitors has scarcely been reported thus far. Herein, two types of MOFs are used as the precursors to prepare CoP and FeP4 nanocubes through a two-step controllable heat treatment process. Due to the advantages of composition and structure, the specific capacitances of FeP4 and CoP nanocubes reach 345 and 600 F g-1 at the current density of 1 A g-1 , respectively. Moreover, a quasi-solid-state asymmetric supercapacitor is assembled based on charge matching principle by employing CoP and FeP4 nanocubes as the positive and negative electrodes, respectively, which exhibits a high energy density of 46.38Wh kg-1 at the power density of 695 W kg-1 . Furthermore, a solar-charging power system is assembled by combining the quasi-solid-state asymmetric supercapacitor and monocrystalline silicon plates, substantiating that the device can power the toy electric fan. This work paves a practical way toward the rational design of quasi-solid-state asymmetry supercapacitors systems affording favorable energy density and long lifespan.

Co2(OH)3Cl and MOF mediated synthesis of porous Co3O4/NC nanosheets for efficient OER catalysis

Functional nanosheets have attracted great attention due to their potential applications in catalysis chemistry and material science. Herein, Co3O4 nanoparticles interconnecting with nitrogen-doped carbon architectures (denoted as Co3O4/NC) was developed on nickel foam surface by a two-step solvothermal process and followed by calcination. A metal organic framework (MOF) of laminar CoMOF-NH2 was synthesized firstly by in-situ transformation of Co2(OH)3Cl array. Then, porous Co3O4/NC nanosheets were obtained by controlled heat treatment of CoMOF-NH2. The Co3O4/NC supported by nickel foam can be directly used as self-supported electrodes for electrocatalysis without any binders. As-synthesized Co3O4/NC acts as effective catalysis for oxygen evolution reaction (OER). Interestingly, the optimized electrochemical efficiency for OER was achieved by Co3O4/NC nanosheet with overpotentials of 235 mV and 264 mV offering current densities of 10 mA/cm2 and 100 mA/cm2, respectively. It also has a relatively low Tafel slope, which indicates the fast electron transfer kinetics of the catalyst. So Co3O4/NC nanosheet has great potential in replacing precious metal electrocatalysts in OER application.

Spray‐Dried TiO2(B)‐Containing Photocatalytic Glass‐Ceramic Nanobeads

AbstractGlass‐ceramic nanospheres of molar composition 0.83 SiO2 · 0.17 TiO2 are produced by the sol‐gel spray‐drying method followed by controlled heat treatments up to 1200 °C. TiO2(B) and anatase nanocrystals are precipitated in the glassy matrix: the latter phase gradually predominates with increasing ceramization temperature and time, in parallel to an overall increase in crystal sizes. The nanospheres exhibit evident photocatalytic activity under UV‐A irradiation, especially at annealing stages involving a comparatively higher amount of TiO2(B) and smaller crystals. The occurrence of TiO2(B) in this simplified binary glass‐ceramic material underlines the key role of this phase in the dynamics of crystallizing TiO2‐bearing silicate melts.

Porous silicon carbide structures with anisotropic open porosity for high- temperature cycling applications

We have prepared porous silicon carbide by a novel two-step template method. Graphite/SiC composites of required size and shape are first fabricated by hot pressing at 2125 °C, followed by the removal of the graphite template by controlled heat treatment. The anisotropy in the composite structure is restored after the removal of the template and porous SiC with anisotropic properties is obtained. The composite can be easily machined by electrical discharge machining because of the presence of graphite, and porous SiC can be obtained by heat treatment, solving the inherent difficulty in the machining of SiC. The mechanical properties, thermal conductivity, and thermal shock resistance of porous SiC have been studied in both directions. The material shows good thermal shock resistance in the perpendicular to pressing direction even at 1400 °C. Hence porous SiC suitably machined preserving the proper direction can be a potential candidate for thermal cycling applications.

Improving the accuracy of axisymmetric parts by applying controlled heat treatment

The article discusses the technology of thermal power treatment of long, non-rigid parts of the “shaft” type. The design of the device for thermal-power deformation of the shaft and the principle of its operation are given. The device is equipped with a three-circuit automatic control system. The control system allows you to control the forces for axial deformation and the temperature of heating and cooling. The developed technology allows us to solve the problem of maintaining the straightness of the shaft during operation.

Structural, optical, and dielectric properties of Bi2O3-K2O-TiO2-P2O5 glasses and related glass-ceramics

ABSTRACT The glasses in the Bi2O3-K2O-TiO2-P2O5 system were elaborated by the conventional quenching method. Their structure was studied by Raman spectroscopy, and additional information is determined from density measurements and thermal analysis. The optical absorption of the glasses is investigated and it is found that the optical gap and the Urbach energy decrease and increase, respectively, with increasing Bi2O3 content. The crystallization of the glasses was performed under controlled heat treatments to develop glass-ceramics. Their dielectric constants are carried out by impedance spectroscopy. The variations of the permittivity (ϵr) and the dielectric loss (tanδ) versus frequency and temperature are determined. It is evidenced that the introduction of Bi2O3 in the glasses diminished the dispersion at low frequencies. The presence of bismuth oxide in the materials is also beneficial since it allowed the formation of glass-ceramics with high dielectric constant and low dielectric loss.

Controlled Heat and Humidity-Based Treatment for the Reuse of Personal Protective Equipment: A Pragmatic Proof-of-Concept to Address the Mass Shortage of Surgical Masks and N95/FFP2 Respirators and to Prevent the SARS-CoV2 Transmission.

Background: The coronavirus infectious disease-2019 (COVID-19) pandemic has led to an unprecedented shortage of healthcare resources, primarily personal protective equipment like surgical masks, and N95/filtering face piece type 2 (FFP2) respirators.Objective: Reuse of surgical masks and N95/FFP2 respirators may circumvent the supply chain constraints and thus overcome mass shortage. Methods, design, setting, and measurement: Herein, we tested the effects of dry- and moist-air controlled heating treatment on structure and chemical integrity, decontamination yield, and filtration performance of surgical masks and FFP2 respirators.Results: We found that treatment in a climate chamber at 70°C during 1 h with 75% humidity rate was adequate for enabling substantial decontamination of both respiratory viruses, oropharyngeal bacteria, and model animal coronaviuses, while maintaining a satisfying filtering capacity.Limitations: Further studies are now required to confirm the feasibility of the whole process during routine practice.Conclusion: Our findings provide compelling evidence for the recycling of pre-used surgical masks and N95/FFP2 respirators in case of imminent mass shortfall.

Sublethal mechanical shear stress increases the elastic shear modulus of red blood cells but does not change capillary transit velocity.

Blood exposure to supraphysiological shear stress within mechanical circulatory support is suspected of reducing red blood cell (RBC) deformability and being primal in the pathogenesis of several secondary complications. No prior works have explored RBC dynamics with the resolution required to determine shear elastic modulus, and/or cell capillary velocity, following exposure to mechanical stresses. Healthy RBCs were exposed to 0, 5, 50, and 100Pa in a Couette shearing system. For comparison, blood was also exposed to heat treatment-a method that predictably increases RBC rigidity. Shear modulus assessment required aspiration of single RBCs through narrow micropipettes at known suction force. Cell transit velocities were measured within microchannels in regions of fully developed flow. Supraphysiological shear stress increased the elastic shear modulus by 39% and 69% following exposure to 50 and 100Pa, respectively. Cell transit velocity, however, did not change following shear, with concurrent decreases in cell volume likely nullifying increased shear modulus-friction interactions. Differences observed were consistent with our internal control (heat treatment), supporting that cell mechanics are significantly impaired following supraphysiological-sublethal shear exposure. Given mechanical circulatory support operates at shear stresses consistent with the present study, it is plausible that these devices induce fundamental impairment to the material properties of RBCs.

A Facile Route to Synthesis of Ferromagnetic and Antiferromagnetic Phases of Iron Oxide Nanoparticles by Controlled Heat Treatment of Ferritin

Magnetic nanoparticles of ferromagnetic and antiferromagnetic phases were synthesized from controlled heat treatment of dry ferritin powder in a bottom-up approach. Heat treatment paves the way for synthesis of Fe2O3 solid phase from iron molecular complexes stored in the cavity of ferritin; the strong increase (~ 150 times) in saturation magnetization is a sign of the presence of ferromagnetic exchange coupling which exists only in solid phase. In this experimental study, vibrating sample magnetometer (VSM) was used to study magnetic induction. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed for analysis of structure and morphology of the samples. Differential scanning calorimetry (DSC) was used to search for indicators of structural phase transformation through scanning of temperature. The nanoparticle size with highly narrow distribution (mean size ~ 6 nm) was observed by SEM for sample annealed at 430 °C. As indicated by XRD measurements, the majority phase of Fe2O3 nanoparticles was amorphous up to 500 °C, whereas DSC demarcates the crystalline phase transition temperature at 545 °C. The annealing temperature range from 400 to 500 °C was found to be suitable for growing ferromagnetic nanoparticles endowed with high saturation magnetization and low coercivity. At higher range of annealing temperature (500–700 °C), XRD confirms the presence of α-Fe2O3 (haematite) phase which is an antiferromagnetic crystalline system with weak magnetization. A systematic decline of magnetization on increasing the annealing temperature beyond 500 °C was attributed to finite size effects and increased purity of antiferromagnetic phase.

Selectively modified nanostructured fluorcanasite glass-ceramic with enhanced micromechanical properties

We report for the first time, synthesis of mesoporous nano-fluorcanasite (n-FC) glass-ceramic from selective glass melting composition using controlled heat treatment and subsequent ball milling. Particle size analysis along with FE-SEM studies confirmed successful synthesis of n-FC particulates with interpenetrating lath like microstructure. XRD study established presence of fluorcanasite, frankamenite, fluorapatite, and xonotlite phases. Pore volume analysis and characteristic adsorption/desorption isotherms of n-FC particulates revealed mesoporous nature with pore diameters in the range of 3 to 15 nm. Interestingly, TEM studies also indicated polycrystalline and mesoporous nature of n-FC particulates and the corresponding ‘d’-spacing values were in good agreement with XRD result. FT-IR spectroscopy further indicated presence of characteristic bands at defined peak positions and crystalline nature of n-FC. Finally, nanoindentation studies indicated enhanced mechanical performance of synthesised n-FC. Overall, our study has established a successful route to synthesise mesoporous nano-fluorcanasite, with favouring microstructure for potential use as bioactive reinforcement.

Investigation of Crystallization and Mechanical Characteristics of Glass and Glass-Ceramic with the Compositions xFe2O3-35SiO2-35B2O3-10Al2O3-(20−x) Na2O

Glass samples with the compositions xFe2O3-35SiO2-35B2O3-10Al2O3-(20 − x) Na2O (0 ≤ x ≤ 1 mol.%) were designed and assembled by melting quenching technique. These samples were investigated by XRD, optical, mechanical, thermal, and FT-IR spectroscopy studies. FT-IR spectra reveal that these glasses are built up of BO3, BO4, and octahedral [FeO6]. The present glasses exhibited the increase in density, thermal parameter values, ultrasonic velocities, elastic moduli, optical band gap (Eopt), and refractive index of the prepared glasses. The corresponding glass-ceramic of these glasses was prepared by controlling heat treatment and investigated with XRD, mechanical, SEM, and TEM. The present glass-ceramics exhibited the increase in density, ultrasonic velocities, and elastic moduli; these values are larger than those of the parent glasses. XRD exhibited the crystalline phases of selected glass-ceramics samples. The transmission electron microscope (TEM) exhibited the grain size of glass-ceramics in nano-size and range between 63.9 and 165 nm. The scanning electron microscope (SEM) exhibited backscattered electron images of the produced glass-ceramics. It is observed that crystalline texture contains relatively large interstitial pores, demonstrating the residual glassy matrix.

Low-cycle fatigue properties of CoCrFeMnNi high-entropy alloy compared with its conventional counterparts

The behavior of CrCoFeMnNi high-entropy alloy (Cantor) during cyclic deformation at room temperature was compared with those of a twinning-induced plasticity (TWIP) steel and 304 stainless steel (SS304). The three materials with similar grain sizes (~65 μm) were made by controlled heat treatment and tested to evaluate tensile and low-cycle fatigue (LCF) properties. The tensile strength and ductility of Cantor were much lower than those of TWIP steel and SS304. Cantor and TWIP steel revealed cyclic hardening and then softening; SS304 showed secondary hardening at the latest stage of cyclic deformation due to formation of α′-martensite, which led to a significant decrease in its LCF life. At high total strain amplitudes >0.4% LCF life was longer in Cantor than in SS304, but shorter than in TWIP steel. However, at total strain amplitudes ≤0.4%, Cantor showed the shortest LCF life. It was found that the Coffin-Manson plot of Cantor followed the trend of TWIP steel rather than that of SS304. Microstructural analysis of the Cantor with increasing cycles revealed the formation of twins and well-defined cell structures, the latter of which is the evidence of wavy slip.

Electrospinning Induced Orientation of Protein Fibrils.

Amyloid-like fibrils are prepared from protein in the lab by controlled heat treatments, yet these must be further assembled to match the desirable mechanical and structural properties of biological fibers. Here, β-lactoglobulin fibrils were incorporated into poly(ethylene oxide) fibers of 40-180 nm diameter by electrospinning. Protein fibrils presented as short segments dispersed within electrospun fibers, with no change in fibril diameter after electrospinning. Imaging analysis revealed fibrils were aligned within 20° relative to the fiber long axis, and alignment was further confirmed by polarized FTIR and anisotropic SAXS/WAXS scattering patterns. The elastic modulus of fibers increased with protein fibril content from 0.8 to 2 GPa, which is superior to reported values of silk, collagen, and gelatin. The present setup allows for manufacture of large quantities of polymeric fibers containing protein fibrils with varied diameter and mechanical strength, endowing great potential for a variety of applications.

Formation of Li3B7O12 and O2BF4 phases from glass system of 0.5LiF-0.5B2O3 containing P2O5 and their structural properties

Borate glass containing lithium fluoride doped with different ratios of phosphate units was produced by conventional melting–annealing technique. Moreover, the produced samples were subjected to two steps of controlled heat treatment in order to achieve the glass–ceramic derivatives (nucleation and crystal growth regimes). Thermal expansion technique revealed that the nucleation temperature for the studied glasses is around 340 °C and the softening temperature (crystal growth) is around 432 °C to form glass–ceramic samples. Li3B7O12 phase was observed as primary phase for the glass–ceramic samples. Also, other crystalline phases such as LiPO3 and O2BF4 were formed. Structural changes of both of the glass and the glass–ceramics were investigated through the Fourier transform infrared technique (FTIR). The active range in the FTIR which distinguishes the glass and the crystalized sample is lying from 400 to 1250 cm−1. The presence of LiF in B2O3 network changes the characteristic units of BO3 and BO4 units into BO2F and BO3F units, respectively.

Balancing strength and ductility by controllable heat-treatment twinning in a near β-Ti alloy

A new thermomechanical process was applied to a near-β Ti-5Al-5Mo-5V-1Cr-1Fe alloy to induce twinning. The resulting combination of ultrafine grains and heat-treatment twins endowed the alloy with excellent tensile strength (1544MPa) and elongation (13%). β-Field cross-rolling formed micro-sized β grains, and ultrafine α particles precipitated from pre-existing dense dislocation structures and martensites. α-Twinning occurred during heat treatment and continuously evolved with the ongoing heat treatment time. A precisely controlled heat treatment time enabled the distribution of nanosized twins throughout the α laths, simultaneously improving strength and ductility. The results of this study pave the way for the development of customised titanium alloys with significantly improved mechanical properties.

In-situ preparation and mechanical property analysis of SiC/SiBCN(O) nanocomposites

In this paper, the dense SiC/SiBCN(O) nanocomposite without obvious crack and/or void was prepared by employing SiBCN(O) amorphous ceramics as starting material. Via controlling heat treatment time of the raw material at 1400 °C, nano β-SiC grains were in situ generated and uniformly dispersed within the amorphous SiBCN(O) ceramic matrix, and the target materials were thus obtained, which may provide a new strategy for fabricating the dense SiBCN(O) based nanocomposties. The influence of dwelling time on chemical composition, grain precipitation and mechanical properties of the materials were also investigated. The experimental results showed that the prepared SiC/SiBCN(O) nanocomposite was dense and pore/crack free, and with the increase in holding time at 1400 °C, the chemical composition of the materials became more uniform and its mechanical properties were significantly improved as well. Particularly, after holding at 1400 °C for 8 h,a number of β-SiC particles with an average size of 28 nm were in-situ precipitated and homogeneously dispersed in the amorphous SiBCN(O) matrix, compared with their counterpart experienced 2 h heat treatment, its nano-hardness, micro-region elastic modulus, flexural stress and elastic modulus were enhanced from ~5 GPa, ~50 GPa, ~40 MPa and ~10.7 GPa, to ~25 GPa, ~190 GPa, ~145 MPa and ~22 GPa, respectively.

Gamma irradiation and crystallization effects on the photoluminescence properties of soda lime fluorophosphates host glass activated with Ce4+, Dy3+ or Pr3+ ions

Selected rare –earth ions –doped in host Na2O–CaF2 – P2O5 glass were prepared by melting – annealing technique. Multi – characterization of the studied doped (CeO2–Pr2O3 – Dy2O3) glasses and their glass – ceramic derivatives were carried out. Optical, photoluminescence, FTIR spectral analysis were measured before and after gamma irradiation. Optical and PL spectra reveal absorption and emission bands which are characteristic for the specific rare earth doped ions which exhibit distinct shielding behavior in CeO2 – doped glass and limited changes by gamma irradiation with the rest of the rare earth – doped glasses. FTIR spectra show characteristic vibrational bands due to main (PO4) groups with the possibility of (PO3F) units and the rare –earth dopants show minor effects on the IR spectra. Gamma irradiation causes a distinct decrease of the intensities of all the IR vibrational bands due to some suggested changes in the bond angles or bond lengths of the network vibrational units. The diffraction patterns due to the phases of the defined crystalline units in the glass – ceramic crystalline phases formed upon controlled heat treatment indicate the formation two sodium phosphate and sodium fluorophosphates phases beside calcium phosphate phase. The crystallization process is assumed to depend on the phase separation process accomplished by the presence of P2O5 and CaO facilitating the latter crystallization process. The calculated optical parameters are found to depend on the structural arrangements in the glass network and their variations through the introduction of the rare – earth dopant and the formation of non-bridging oxygens.

Interaction Mediator Assisted Synthesis of Mesoporous Molybdenum Carbide: Mo-Valence State Adjustment for Optimizing Hydrogen Evolution.

To overcome inherent limitations of molybdenum carbide (MoxC) for hydrogen evolution reaction (HER), i.e., low density of active site and nonideal hydrogen binding strength, we report the synthesis of valence-controlled mesoporous MoxC as a highly efficient HER electrocatalyst. The synthesis procedure uses an interaction mediator (IM), which significantly increases the density of active site by mediating interaction between PEO-b-PS template and Mo source. The valence state of Mo is tuned by systematic control of the environment around Mo by controlled heat treatment under air before thermal treatment at 1100 °C. Theoretical calculations reveal that the hydrogen binding is strongly influenced by Mo valence. Consequently, MoxC achieves a significant increase in HER activity (exceeding that of Pt/C at high current density ∼35 mA/cm2 in alkaline solution). In addition, a volcano-type correlation between HER activity and Mo valence is identified with various experimental indicators. The present strategies can be applied to various carbide and Mo-based catalysts, and the established Mo valence and HER relations can guide development of highly active HER electrocatalysts.