Thermal Treatment Process Research Articles

Effect of different thermal processing methods and thermal core temperatures on the protein structure and in vitro digestive characteristics of beef

This study aimed to investigate the effect of different thermal processing treatments on the protein digestion characteristics of beef. The beef samples were subjected to different cooking methods, namely steaming, boiling, and roasting, and different core temperatures (75 °C, 80 °C, 85 °C, and 90 °C), and were subjected to in vitro gastrointestinal digestion simulation. All the thermal processing treatments increased the protein digestibility; the samples that were steamed at 85 °C (S85), boiled at 80 °C (B80), and roasted at 80 °C (R80) showed the biggest gains. The S85 released more peptide species after gastrointestinal digestion, according to peptididomic studies. These differences were closely related to protein structure. Thermal processing treatments resulted in a higher degree of proteolysis and looser protein conformation, as evidenced by decreased intrinsic fluorescence and electrophoretic band intensity, increased surface hydrophobicity, and the change in protein secondary structure from α-helix to β-sheet and random coil. Based on the results, S85 was identified as the optimal thermal processing treatment for enhancing the digestibility of beef protein. The results provide valuable insights into the nutritional qualities and digestion of heat-processed beef protein.

Exploring 99mTc-Labeled Iron-Binding Glycoprotein Nanoparticles as a Potential Nanoplatform for Sentinel Lymph Node Imaging: Development, Characterization, and Radiolabeling Studies.

Lactoferrin, an iron binding glycoprotein-based nanoparticle, has emerged as a promising platform for drug delivery and imaging. This study presents the potential use of the protein nanocarrier in tracking sentinel lymph nodes for cancer staging. Lactoferrin nanoparticles (LF-NPs) were synthesized using a thermal treatment process and optimized to obtain 60-70 nm particle size with PDI less than 0.2. The NPs were characterized microscopically and spectroscopically, ensuring a comprehensive understanding of their physicochemical properties. The LF-NPs were found to be stable in different pH conditions. Their biocompatibility was confirmed through cytotoxicity assessments on RAW 264.7 cells, and hemolysis assay and in vivo toxicity study reveal their safe profile. Additionally, LF-NPs were successfully radiolabeled with technetium-99m (>90% labeling yield). Cell uptake studies with RAW 264.7 exhibited an uptake of ∼6%. Biodistribution studies in Wistar rats shed light on their in vivo behavior and suitability for targeted drug delivery systems. These findings collectively emphasize the multifaceted utility of LF-NPs, positioning them as a promising platform for diverse biomedical innovations.

Impact of Thermal Processing on the Structure, Antioxidant Properties and Hypoglycemic Activities of Sweet Potato Polysaccharides.

In this study, three kinds of thermal treatments were applied to sweet potatoes: steaming (100 °C, 20 min), frying (150 °C, 10 min), and baking (200 °C, 30 min). We analyzed the changes in the physicochemical structure, antioxidant properties, and hypoglycemic activities of sweet potato polysaccharides between untreated and heat-treated samples. The results showed that the polysaccharides of all sweet potatoes (untreated and heat-treated) were composed of pyranose structures, had low protein content, and shared the same monosaccharide composition. Infrared spectra showed that the three thermal processing treatments had no significant effect on the functional groups or chemical bonding of sweet potato polysaccharides. In addition, all four polysaccharides exhibited dose-dependent antioxidant and hypoglycemic activities. The above experimental results suggest that thermal processing did not affect the physicochemical, antioxidant, or hypoglycemic activities of sweet potato polysaccharides.

Effect of pilot-scale high-temperature short-time processing on the retention of key micronutrients in a fortified almond-based beverage: implications for fortification of plant-based milk alternatives.

The effect of thermal processing treatments on key micronutrients in fortified almond-based beverages has not been well characterized. An almond-based beverage was produced in a pilot plant, fortified with vitamin A palmitate, vitamin D2, riboflavin (vitamin B2), calcium carbonate, and zinc gluconate, and was processed using various high-temperature short-time (HTST) pasteurization treatments. Naturally present micronutrients in the base ingredients included several B vitamins (vitamin B1 [thiamin], total vitamin B3 [sum of nicotinamide and nicotinic acid], and total vitamin B6 [sum of pyridoxal, pyridoxamine, and pyridoxine]) and minerals (magnesium, phosphorus, and potassium). The prepared almond-based beverage was homogenized and thermally processed using HTST pasteurization with a temperature range from ~94 to 116°C for a constant time of 30 s. The samples were analyzed for vitamin A palmitate, vitamin D2, target B vitamins (thiamin, riboflavin, total vitamin B3, and total vitamin B6), and minerals (magnesium, phosphorus, potassium, calcium, and zinc). The results showed that amounts of vitamin A, vitamin D2, riboflavin, and total vitamin B6 did not significantly (p > 0.05) change after the HTST treatments, whereas thiamin significantly (p < 0.05) decreased by 17.9% after HTST treatment at 116°C. Interestingly, total vitamin B3 content significantly (p < 0.05) increased by 35.2% after HTST treatment at 116°C. There was no effect of processing on the minerals that were monitored. The results from this study indicate that the majority of key micronutrients assessed in this study are stable during HTST processing of an almond-based beverage and that fortification of plant-based milk alternatives may be a viable process to enhance the micronutrient content consumers receive from these products.

Increased interlayer spacing N-doping Ti3C2Tx MXene-based mezzanine heterostructure for enhanced performance lithium/sodium storage

Structure of the electrode materials play a critical role in electrochemical performance for both lithium-ion batteries and sodium ion batteries. Herein, MXene modified by element doping and compositing metal–organic frameworks (MOF)-based Fe2O3@Carbon nanofibers (CNFs) with a mezzanine heterostructure, is constructed to achieve low interfacial impedance, high specific capacity stability in lithium/sodium storage processes. The prepared mezzanine heterostructure Fe2O3@C@N-Ti3C2Tx composite is highly conductive and mesoporous. During the nitrogen-doping thermal treatment process, the interlayer spacing of Ti3C2Tx MXene was increased, providing wider ion transport channels. Additionally, inert carbon atoms were transformed into electrochemically active nitrogen atoms, leading to the construction of more active centers and surface defects. The spatial confinement of N-Ti3C2Tx MXene during the electrochemical process, effectively mitigating volume expansion and maintaining structural stability upon applied as electrode materials. Benefitting from the unique 3D conductive network, the mezzanine heterostructure Fe2O3@C@N-Ti3C2Tx composite nanofibers exhibits excellent Li/Na storage performance. In LIBs, it delivers a capacity of 226 mAh/g at 10 A/g and retains 314 mAh/g after 2800 ultra-long cycles at 5 A/g. For SIBs, it exhibits a capacity of 135 mAh/g at 5 A/g and maintains 209 mAh/g after 3000 cycles at 2 A/g.

Preparation of novel ACMO-AA/PVDF composite membrane by one-step process and its application in removal of heavy metal ions from aqueous solutions

In this study, a simple one-step process was used to fabricate a high-efficiency 4-acryloylmorpholine-acrylic acid/polyvinylidene fluoride (ACMO-AA/PVDF) composite membrane for the adsorption of heavy metal ions. The initiation phase involved the use of the strong organic base tetramethylammonium hydroxide (TMAH) to facilitate the partial dehydrofluorination of PVDF, thereby yielding a reactive CC bond. Following this, undesirable residuals and by-products of TMAH were removed through a thermal treatment process. Subsequently, an ACMO and AA, both possessing distinctive functional groups, onto the active CC bond took place in-situ. The use of a suitable initiator (AIBN) and crosslinking agent (MBA) facilitated the copolymerization process, culminating in the production of the ACMO-AA/PVDF composite membrane with excellent capability for the adsorption of heavy metal ions. Performance evaluations confirmed the membrane high efficiency in Pb2+ removal with complete removal realized at initial Pb2+ concentrations of ≤50 mg·L–1 and presenting a maximum adsorption capacity of 1214.75 mg·g–1, as described by the Langmuir model. In complex environments with co-existing metal ions such as Cu2+, Hg2+, and Cd2+, at an each initial concentration of up to 50 mg·L–1, the membrane exhibited a Pb2+ removal rate of 93.81 %, and Hg2+ and Cu2+ removal rates of 93.75 % and 92.93 %, respectively. The results of surface morphological and microstructural analyses showed that the principal adsorption mechanism is chemical chelation. Furthermore, the membrane exhibited sustainable usability, retaining its structural integrity and adsorption efficacy over multiple regeneration cycles. This indicates that the ACMO-AA/PVDF composite membrane is a viable candidate for deep decontamination processes involving Pb2+, Hg2+, and Cu2+ in environmental remediation applications.

Annealing characteristics and mechanism interpretation of high-performance swaged W-Y2O3 alloy

The evolution of the internal microstructure of tungsten (W) alloys during thermal mechanical processing and annealing is complex. This study employs systematic annealing experiments, tensile tests, and microstructural characterization to scientifically analyze a high-performance W-Y2O3 (WYO) alloy post-swaging. The aim is to gain a thorough understanding of the microstructural basis of the material's properties and to explore the relationship between these property changes and the annealing process. We quantify the trends of low-angle grain boundaries under various annealing temperatures, revealing their strong correlation with the ductility of W alloys. Annealing swaged WYO below the recrystallization temperature effectively enhances its mechanical properties. Findings not only provide scientific support for the further application and development of W alloys but also offer valuable insights into how mechanical and thermal treatment processes can optimize material properties.

Heat and mass transport micropolar Maxwell and Williamson nanofluids flow past a perpendicular cylinder using combined convective flow

The current study aims to investigate the heat and mass transport characteristics of micropolar Maxwell and Williamson nanofluids flowing past a perpendicular cylinder under the influence of combined convective flow using the Buongiorno nanofluid model. The objective is to analyze the axisymmetric flow of these nanofluids around an orthogonal cylinder, highlighting the effects of various physical parameters on temperature profiles and velocity distributions. Maple 23 software was employed to solve the coupled nonlinear differential equations derived from appropriate similarity transformations. The numerical results are presented in tabular and graphical form to show the impacts of key parameters on the selected micropolar nanofluids. The significant outcomes show that the skin friction coefficient, as well as the Nusselt and Sherwood numbers, increase along the axial direction, indicating enhanced heat and mass transfer capabilities. Additionally, the study emphasizes the roles of micro polarity, relaxation time, and viscoelastic properties in modulating these transfer processes. These findings have significant implications for applications in biomechanics, polymer manufacturing, aerosol deposition, and thermal treatment processes, offering valuable insights for future research and industrial practices.

Формирование свойств биодеградируемых пленок на основе рыбного желатина

Nowadays in the food and nutrition industry special attention is paid to the creation of non-toxic, easily recy-clable packaging materials of a new assortment, capable of providing reliable protection of products from harmful factors. The object of the study was biodegradable film compositions based on fish gelatin and agar, with the addition of plasticizing agent - glycerol. Experimental and analytical studies were carried out using standard and original methods. Modeling of the process of thermal treatment of film compositions was carried out, the experimental dependence of moisture absorption of films on temperature (range 120-160 °C) and duration of the thermal modification process (10-30 minutes) was established. The possibility of thermal modification of biodegradable film compositions was determined. The rational mode of thermal treatment of films is the temperature interval of 140 °C for 20 minutes, which allows to keep the moisture absorption index at the maximum level (842%), exceeding the initial index by 8.4 times, during 120 hours. The established parameters of thermal structuring allow to keep organoleptic quality indicators of films at a high level and to obtain a homogeneous, porous and elastic film. Thermally modified films at temperatures of 140 and 160 °C are characterized by increased dissolution time up to 40 and 70 minutes respectively at dissolution temperature of 60 °C and up to 15 and 30 minutes respectively at dissolution temperature of 75 °C. It is shown that thermal modification of biodegradable films will contribute to compliance with safety requirements, environmental friendliness, absence of toxicity. Thermal modification allows to increase functional and technological properties of composite biodegradable films, which can be used to create a wide range of modern packaging barrier materials.

Synthesis of Molybdenum Oxide Nanofibers with Multiple Surface Facets Via Electropsinning Followed by Rapid Thermal Treatment

A MoO3 nanofiber prepared by electrospinning and subsequent heat treatment is attracting significant attention due to its structural advantages. Vibrant studies are being conducted to control its morphology and diameter to improve its properties. In this study, we demonstrated the synthesis of α-MoO3 nanofibers with multiple surface facets by controlling the heating rate and temperature in the heat treatment step for removing polymer and crystallizing MoO3 from the electrospun polymer/precursor nanofibers. The analysis results show that the faster heating rate and higher heat treatment temperature in the thermal treatment process are more favorable for forming a shape in which particles with facet planes are connected. Finally, we observed the morphological change according to the heat treatment time to confirm the effect of the heat treatment conditions on the shape of MoO3 and interpreted the results in terms of nucleation and crystal growth.

Impact of Lime Saturation Factor on Alite-Ye'Elimite Cement Synthesis and Hydration.

Alite(C3S)-Ye'elimite(C4A3$) cement is a high cementitious material that incorporates a precise proportion of ye'elimite into the ordinary Portland cement. The synthesis and hydration behavior of Alite-Ye'elimite clinker with different lime saturation factors were investigated. The clinkers were synthesized using a secondary thermal treatment process, and their compositions were characterized. The hydrated pastes were analyzed for their hydration products, pore structure, mechanical strength, and microstructure. The clinkers and hydration products were characterized using XRD, TG-DSC, SEM, and MIP analysis. The results showed that the Alite-Ye'elimite cement clinker with a lime saturation factor (KH) of 0.93, prepared through secondary heat treatment, contained 64.88% C3S and 2.06% C4A3$. At this composition, the Alite-Ye'elimite cement clinker demonstrated the highest 28-day strength. The addition of SO3 to the clinkers decreased the content of tricalcium aluminate (C3A) and the ratio of Alite/Belite (C3S/C2S), resulting in a preference for belite formation. The pore structure of the hydrated pastes was also investigated, revealing a distribution of pore sizes ranging from 0.01 to 10 μm, with two peaks on each differential distribution curve corresponding to micron and sub-micron pores. The pore volume decreased from 0.22 ± 0.03 to 0.15 ± 0.18 cm3 g-1, and the main peak of pore distribution shifted towards smaller sizes with increasing hydration time.

A novel approach for environmentally benign synthesis and solid-state polymerization of fluorinated polyimides in aqueous co-solvent

This study presents a novel approach that enables an environmentally benign water-based co-solvent synthesis of fluorinated polyimides (FPIs) using conventional fluorine-based monomers such as 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 2,2′-bis(trifluoromethyl)benzidine (TFMB). The high surface tension inherent in fluorine-based materials, which inhibits water solubility, can be overcome by mixing water with an alcohol-based solvent. The surface tension of the co-solvent decreases proportionally with the alcohol content, facilitating synthesis from fluorine-based monomers that were previously inaccessible in water. Oligomeric fluorinated poly(amic acid) salt (FPAAS) can be rapidly synthesized in aqueous solutions containing alcohol, particularly 1-propanol (PrOH). Subsequent coating and thermal treatment processes allow high molecular weight FPI films to be produced by solid-state polymerization. A comprehensive analysis of the resulting FPI films shows excellent physical properties comparable to conventionally synthesized FPI films. The 6FDA-TFMB-based FPI exhibits remarkable thermal stability up to 570 °C (Td,5%), low yellow index of 1.37, high transparency of 92.9 % and tensile strength of 116.5 MPa. The presented synthetic strategy allows the adoption of monomers with different fluorine-based substituents, thus providing insights for future aqueous synthesis. The thermal, mechanical, and optical qualities of FPIs can be utilized to create optically clear heating devices. The transparent heater, fabricated on the FPI film utilizing a laser patterning technique to create electrodes from silver nanowires, was capable of increasing the temperature up to 100 °C under a 9 V voltage application.

Interfacial design of support substrate for a continuous mesophase-templated active layer with adjustable pore size

Nano-porous active layers templated by hexagonal lyotropic liquid crystal (HLLC) offer a continuous water pathway, rendering them promising for membrane separation applications of high performance. The surface properties, such as surface roughness, hydrophilicity and pore size, of commercially available ultrafiltration membranes usually need to be optimized to better support the active layer. Here, we apply a facile yet potent thermal treatment process to a polyacrylonitrile ultrafiltration (UPAN) substrate and form a continuous HLLC separation layer. The enhancement in water filtration performance is largely influenced by the surface roughness of the substrates. As the temperature increases, the UPAN substrates become rougher due to approaching the glass transition temperature of polyacrylonitrile. This leads to a denser HLLC active layer with smaller pores. For the membranes treated at a temperature of 100 °C, their water flux reaches 17 L/m2h, which is 10 times higher than that of the membranes treated at 85 °C, and the PEG4000 rejection increases by almost 50 % from 42 % to 59 %. This heat treatment process offers a novel approach to fabricate mesophase-templated active layers with adjustable pore sizes, thus advancing membrane separation techniques.

Effects of polymer matrix and temperature on pyrolysis of tetrabromobisphenol A: Product profiles and transformation pathways

Plastics are crucial constituents in electronic waste (e-waste) and part of the issue in e-waste recycling and environmental protection. However, previous studies have mostly focused on plastic recovery or thermal behavior of flame retardants, but not both simultaneously. The present study simulated the process of e-waste thermal treatment to explore tetrabromobisphenol A (TBBPA) pyrolysis at various temperatures using polystyrene (PS), polyvinyl chloride (PVC), and e-waste plastics as polymer matrices. Pyrolysis of TBBPA produced bromophenol, bromoacetophenone, bromobenzaldehyde, and bromobisphenol A. Co-pyrolysis with the polymer matrices increased emission factors by 1 − 2 orders of magnitude. The pyrolytic products of TBBPA, TBBPA+PS, and TBBPA+PVC were mainly low-brominated bisphenol A, while that of TBBPA in e-waste plastics was consistently bromophenol. Increasing temperature drove up the proportions of gaseous and particulate products, but lowered the relative abundances of inner wall adsorbed and residual products in pyrolysis of pure TBBPA. In co-pyrolysis of TBBPA with polymer matrix, the proportions of products in different phases were no longer governed solely by temperature, but also by polymer matrix. Co-pyrolysis of TBBPA with PS generated various bromophenols, while that with PVC produced chlorophenols and chlorobrominated bisphenol A. Transformation pathways, deduced by ab initio calculations, include hydrogenation-debromination, isopropylphenyl bond cleavage, oxidation, and chlorination.

Effect of stabilization and carbonization treatment on the chemical and physical transformation of polyacrylonitrile (PAN) based electrospun carbon nanofibers

The present study delves into the production of carbon nanofibers (CNFs) utilising electrospun polyacrylonitrile (PAN) nanofiber mats, with a specific focus on the influence of oxidative stabilisation and carbonisation treatments. This research aims to thoroughly understand how variations in stabilisation time and temperature, as well as carbonisation temperature, impact the CNFs properties. These properties include fiber size, morphology, chemical and crystal structure transformation, thermal behaviour, and surface characteristics. Our methodology involved a detailed examination of the thermal treatment processes, where we observed a significant decrease in fiber size, though the surface morphology of the fibers remained largely unaffected. We employed Fourier-transform infrared (FTIR) spectroscopy to track the transformation of nitrile groups in PAN to imine groups, which indicated the progression of cyclisation reactions. Complementary analyses through differential scanning calorimetry (DSC) confirmed a high degree of these reactions, particularly at stabilisation temperatures extending to 250 °C and beyond. The cyclisation process was found to be complete during the carbonisation phase, at temperatures reaching 450 °C and above. Further, x-ray diffraction (XRD) patterns offered insight into the changes in the crystal structure, particularly in the packing of the d(002) spacing because of the stabilisation and carbonisation processes. This findings from this study not only elucidate the intricate process of CNFs production from electrospun PAN nanofiber mats but also highlight the critical factors that influence their final properties. These insights are invaluable for the development of advanced CNFs with tailored properties suitable for a range of applications, including but not limited to energy storage, electronics, and as supporting materials in various technological domains.

Modified Amber Particles as a Stabilizer to Construct Oil-in-Water Pickering Emulsions for Improved Thermal Stability of Acorus tatarinowii Essential Oil.

Lingzhu Pulvis is a classic formulation for treating febrile convulsions in children. However, Acorus tatarinowii essential oil (AT-EO) in this prescription is prone to volatilization and oxidation, compromising the efficacy and quality control of this formulation. Herein, based on the concept of "combination of medicine and adjuvant", Pickering emulsion technology was applied to enhance the stability of AT-EO using modified amber as a stabilizer. Amber was a resinous medicinal powder in Lingzhu Pulvis and was modified into a suitable stabilizer for Pickering emulsion through surface modification. A thermal stability study indicated that Pickering emulsion, stabilized by modified amber, exhibited a higher retention rate of AT-EO and lower levels of peroxide value and malondialdehyde content compared to those of the pure AT-EO group after heat treatment at 40 °C for 1, 3, and 8 h. Additionally, component analysis in content and composition revealed that the volatile components of AT-EO in the Pickering emulsion were more stable during the thermal treatment process. This study convincingly illustrates the potential of a Pickering emulsion stabilized with modified medicinal powders to improve the thermal stability of the essential oil.

Effects of thermal processing on the nutritional and antinutritional properties of African yam bean (Sphenostylis stenocarpa) seed flours

The study was carried out to evaluate the effects of thermal processing treatments on nutrient and antinutrient contents of African yam bean seed flours. The African yam bean seeds were sorted, cleaned and divided into five equal lots of one kilogram each. Four lots were processed into boiled, blanched, roasted and autoclaved African yam bean flours, while the last lot was processed raw and used as control. The flour samples obtained were analysed for proximate, mineral, vitamin and antinutrient contents using standard methods. The proximate composition of the samples revealed that the flours had a range of 6.14-11.24% moisture, 8.18-14.37% crude protein, 3.06-4.61% fat, 2.04–3.32% ash, 3.18–3.56% crude fibre, 62.90–76.98% carbohydrate and 350.57–368.50 kJ/100g energy, respectively. The mineral composition of the samples showed that the flours contained 128.81–174.16 mg/100g calcium, 88.86–212.20 mg/100g, potassium, 134.71–166.77 mg/100g phosphorus, 89.17 – 122.76 mg/100g, magnesium, 14.28–18-11 mg/100g iron and 3.24–5.59 mg/100g zinc, respectively. The vitamin composition of the flours were 1.15–1.37 mg/100g ascorbic acid, 1.15–135 mg/100g thiamine, 1.19–1.55 mg/100g niacin, 1.34–1.85 mg/100g riboflavin, 1.09–1.29 mg/100g folic acid, 1.37–1.95 mg /100g vitamin A and 1.27–1.66 mg/100g vitamin E, respectively. The results showed that the roasted and autoclaved African yam bean flours generally had higher crude protein, fat, ash, crude fibre, mineral and vitamin contents than the boiled and blanched flour samples compared to the raw sample. The antinutrient composition of the flours also showed that the levels of trypsin inhibitor activity, tannin, phytate, oxalate, saponin and haemagglutinin of the samples were significantly (p&lt;0.05) reduced by boiling, autoclaving roasting and blanching treatments compared to the raw sample. However, the study revealed that the processed African yam bean flours have the potentials to be used as nutrient dense ingredients in the preparation of a wide range of food products than the raw sample especially in both underdeveloped and developing countries where the problems of protein-energy malnutrition and micronutrients deficiencies are prevalent.

Thermally stabilized polyacrylonitrile/polyphenylene sulfide composite membranes for efficient emission control in harsh environments

In harsh and complex environments, the emission of polluted air poses significant challenges to traditional filtration systems. In contrast to conventional approaches which primarily involve the incorporation of antioxidants into filter materials, this study introduces a novel methodology. Here, we employed polyacrylonitrile (PAN) as a coating for polyphenylene sulfide (PPS) fibers. Furthermore, we innovatively utilized a needle punching process in conjunction with segmented heat treatment to manufacture PAN-PPS composite filter membranes capable of withstanding extreme environmental conditions. During the segmented heat treatment process, the molecular structure of PAN coating underwent a series of changes, ultimately transforming into a heat-resistant ring trapezoidal structure, providing protection for PPS fibers that are prone to oxidation, and thereby enhancing the structural stability of composite filter membrane. Experimental results demonstrated a significant improvement in the mechanical properties of PAN-PPS composite fabric after segmented heat treatment, with the tensile strength increasing by 71.7 % and the Young’s modulus by 91.6 %. Additionally, the flame retardancy and hydrophobic properties of composite membranes were significantly enhanced, exhibiting the excellent stability and better filtration performance in extreme environments. This approach not only addresses the challenges posed by incorporating nano antioxidants into the spinning process but also significantly enhances the high-temperature resistance of the materials. This enables PAN-PPS composite filter bags to effectively control the emission of polluted gases in extreme environments. Furthermore, the thermal treatment process of the PAN coating is easy to implement and cost-effective, providing a novel strategy for the development of extremely high-temperature resistant filtering materials. This makes it possible to explore the development of flexible, high-performance air filtering materials for extreme environments in the future.

Thermal cycle stability and microstructure of Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals

The Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) ferroelectric single crystals have been commercially available as important components in medical ultrasound transducers due to their excellent piezoelectric and electromechanical coupling performance. The variation in piezoelectric and dielectric properties of PMN-PT single crystals with ambient temperature is an important application indicator. In this work, the PMN-PT single crystals after direct current poling (DCP) and alternating current poling (ACP) were subjected to the cyclic thermal treatment process. The thermal cycling stability and microstructural changes in PMN-PT single crystals were investigated. The ACP single crystals exhibit a higher dielectric constant ε33T/ε0 (6500–7600) and piezoelectric coefficient d33 (2100–2500 pC N−1) compared to the DCP single crystals (ε33T/ε0 of 4100–5000, d33 of 1200–1300 pC N−1). Under thermal cycling at 60 °C, the DCP and ACP single crystals exhibit good thermal cycling stability after 150 cycles. Microstructural observations show that the domain structure of the DCP single crystals exhibits “staggered domain walls, inhomogeneous domain size, variety of domain structure,” while the relatively homogeneous stripe-like domains were observed in the ACP single crystals. After thermal cycling, new fine striped domains appear in both the DCP and ACP single crystals due to the instability of rotated polarization, but the piezoelectric and dielectric properties are not greatly affected. This work provides an intensive understanding of the effects of thermal cycling on the domain structure, which is useful for applications.

Mechanical Behavior and Shape‐Memory Effects of NixTi1−x Alloys with Tunable Mixing of Ni/Ti Powders by Laser‐Directed Energy Deposition

As it is known, controlling NiTi alloy's microstructure is an urgent problem in additive manufacturing, which directly affects the mechanical properties of the alloy. In laser‐directed energy deposition (LDED) technology, the simultaneous powder feeding equipment with double powder barrels can effectively control the material ratio and realize the generation of NixTi1−x alloys with different atomic ratios. First, the performance differences of NiTi alloy under different thermal treatments are explored. Based on this, the optimal thermal treatment process is used to adjust the microstructure of NiTi alloy fabricated by LDED by changing the Ni/Ti atomic ratio to improve mechanical properties. The results indicate that Ni4Ti3 precipitates can induce the R phase, change the phase transition, and improve the mechanical properties in Ni‐rich NiTi alloys. Besides, the mechanical properties of NixTi1−x alloy can be enhanced by adjusting the Ni/Ti atomic ratio to change the content of Ni4Ti3 precipitates. Ni52Ti48 alloy has a tensile strength of 771 MPa, an elongation of 11.6%, and a recovery rate of 95.2%.