Melting Point Research Articles

Anion‐repulsive polyoxometalate@MOF‐modified separators for dendrite‐free and high‐rate lithium batteries

AbstractCommercial polyolefin separators in lithium batteries encounter issues of uncontrolled lithium‐dendrite growth and safety incidents due to their low Li+ transference numbers () and low melting points. To address these challenges, this study proposes an innovative approach by upgrading conventional separators through the incorporation of metal‐organic framework (MOF)‐confined polyoxometalate (POM). The presence of POM restricts anion diffusion through electrostatic repulsion while facilitating Li+ transport within MOF nanochannels through their affinity for lithium ions. Moreover, MOF confinement effectively mitigates the acidification of electrolytes induced by POM. As a proof‐of‐concept, the polypropylene separators decorated with phosphotungstic acid@UIO66 (denoted as PW12@UIO66‐PP) exhibit remarkable lithium‐ion conductivity of 0.78 mS cm−1 with a high of 0.75 at room temperature. The modified separators also display excellent thermal stability, preventing significant shrinkage even at 150°C. Furthermore, Li symmetric cells employing PW12@UIO66‐PP separators exhibit stable cycling for 1000 h, benefiting from rapid Li‐ion transport and uniform deposition. Additionally, the modified separator shows promising adaptability to industrial manufacturing of lithium‐ion batteries, as evidenced by the assembly of a 4 Ah NCM811/graphite pouch cell that retains 97% capacity after 350 cycles at C/3, thus highlighting its potential for practical applications.

LiTFSI salt concentration effect for well‐balanced ion transport and physical properties in nanocellulose‐reinforced PEO#600 solid electrolytes

AbstractPoly(ethylene oxide) (PEO) with an oxygen group serves as a reactive site for the pathway of lithium‐ion transport. Reducing the PEO crystal domain in solid electrolytes is an extremely efficient approach for enhancing the mobility of ions. The present study applied various EO/Li molar ratios to modify the physical and electrochemical properties of PEO nanocomposite reinforced by nanocellulose. An elevated lithium salt concentration causes a gradual decline in crystallinity and mechanical strength. The electrochemical performance of the 13 EO/Li molar ratio voltammogram and charge–discharge shows efficient Li‐ion transport with 5.6 × 10−4 S/cm conductivity at room temperature and 131 mA h g−1 initial discharge capacity. The shifting glass transition and melting point at lower temperatures (−40.5 to −44.5°C and 45.3–43.8°C) suggest greater ion mobility throughout the large non‐crystalline structure. Lithium ions are limited by membrane weakening and re‐crystallization caused by high lithium salt (EM_11) concentrations. EM_13 has the highest specific capacity, operating voltage, and lithium transfer number depends on balanced electrochemical performance and physical features. XPS surface chemistry analysis explains LiF, Li2CO3, and Li2O solid electrolyte interfaces (SEI) in EM samples. A lower Li2O (11.62 at.%) than LiF (38.4 at.%) after cycling enhances Li‐ion diffusion and cell reversibility.

Investigation on titanium wire melting through high-frequency induction heating for additive manufacturing process

ABSTRACT A high-frequency induction heating (HFIH) system is a novel and clean heat source that can potentially melt high melting point material to develop the wire feed-based additive manufacturing (AM) process. The present study establishes the optimised coil parameters, including coil geometry for melting the titanium wire using induction heating. A fully coupled electromagnetic-thermal-fluid flow model is established to analyse the temperature profile of the wire. The wire feed velocity (0.012 m/s) is incorporated in the coupled model using the deformed mesh method. Optimised wire diameter and coil parameters, such as a three-turn helical coil with a circular cross-section, coil turn spacing of 1.5 mm, and a coupling distance of 4 mm, melt the 3.6 mm titanium wire rapidly and create the molten droplet. The results suggest that the optimised coil parameters improve the magnetic flux density, which enhances joule heating in the wire. However, the conical-spiral coil geometry of the three-turn fails to melt the wire completely. In contrast, the helical coil of the three-turn melts the wire completely. The maximum velocity of the molten metal is found as 0.25 m/s. Effectively, the heat transfer and material flow analysis drives to develop the potential additive manufacturing system.

On the Electrochemical Properties of Poly(Vinylidene Fluoride)/Polythiophene Blends Doped with Lithium‐Based Salt

AbstractIn this study, polymer blends of polythiophene (PTH) and poly(vinylidene fluoride) (PVDF) are investigated by focusing on their structural and electrochemical characteristics. These blends displayed immiscibility confirmed through field emission scanning electron microscopy (FE‐SEM) and interaction assessments. PTH's role as a plasticizer is evident, diminishing crystallinity. A rise in PTH level led to a lower glass transition temperature and a higher melting point, suggesting reduced intermolecular forces and increased polymer chain flexibility. Conversely, a dispersed phase presence elevated the melting point, restricting chain movement and crystallization. The thermal properties of blends are enhanced by increased PTH content. Applying the Vogel–Tammann–Fulcher model to ionic conductivity measurements, it observed a direct relationship between temperature and free volume, impacting conductivity and ion transport numbers. Certain materials exhibit increased activation energies, indicating substantial thermodynamic barriers to local motion. Higher PTH content within the PVDF matrix notably increased the lithium ion transfer number from 0.22 to 0.71, a change tied to the C–S–C structure of polythiophene. However, elevated PTH levels also led to diminished negative charge transfer and ionic conductivity in the PTH‐PVDF blend compared to pure PVDF, likely due to an ionic conduction hindrance.

Recent Advances in Additive Friction Stir Deposition: A Critical Review.

Additive friction stir deposition (AFSD) is a novel solid-state additive manufacturing method developed on the principle of stirring friction. Benefits from its solid-phase properties, compared with traditional additive manufacturing based on melting-solidification cycles, AFSD solves the problems of porosity, cracks, and residual stress caused by the melting-solidification process, and has a significant improvement in efficiency. In AFSD, the interaction between feedstocks and high-speed rotating print heads suffers severe plastic deformation at high temperatures below the melting point, ending up in fine, equiaxed recrystallized grains. The above characteristics make components by AFSD show similar mechanical behaviors to the forged ones. This article reviews the development of AFSD technology, elaborates on the basic principles, compares the macroscopic formability and material flow behavior of AFSD processes using different types of feedstocks, summarizes the microstructure and mechanical properties obtained from the AFSD of alloys with different compositions, and finally provides an outlook on the development trends, opportunities, and challenges to the researchers and industrial fields concerning AFSD.

Synthesis, characterization, and biological potential of 2-thiophene carbaldehyde o-phenylenediamine Schiff base and its Cr(II), Mn(II), and Fe(II) Complexes

A Schiff base was produced through the chemical reaction of 2-thiophene carbaldehyde with o-phenylenediamine. The corresponding metal (II) chlorides were refluxed with the Schiff base to produce the complexes of Cr (II), Mn (II), and Fe (II). These complexes were then characterized by elemental analysis, FT-IR, atomic absorption spectroscopy, solubility, melting/decomposition temperature, and magnetic susceptibility. The vibrational peak at 1622 cm̄1 in the FT-IR spectral data of the Schiff base was ascribed to the vibration frequencies of azomethine u(C=N). But in the complexes, it was discovered that the azomethine band shifted between 1614 and 1659 cm̄1 , suggesting that they were involved in the complexes’ creation. The complexes’ measured absorption bands in the range of 713–769 cm1 were attributed to the M–N bond, indicating the occurrence of metal–nitrogen bonds. The complexes exhibit non-electrolyte properties attributed to their low molar conductance values ranging from 8.00 to 29 Ohm̄1 cm̄ ²mol̄¹. The determination of the melting point of the Schiff base yielded 120 °C, while the decomposition temperature fell within the range of 149–160 °C for the complexes, indicating their thermal stability. Analysis of magnetic susceptibility indicated an octahedral geometry for all the complexes, with values ranging from 2.24 to 3.12 BM. The elemental should analysis of both the Schiff base and its metal (II) complexes for C, H, and N indicated a close agreement between observed and calculated percentages, suggesting a consistent 1:2 metal-Schiff base ratio across all complexes. The qualitative analysis of the compounds confirmed the presence of chloride, which was quantified and determined to range from 4.62% to 7.90%. The prepared Schiff base and its metal (II) complexes underwent evaluation for their antibacterial efficacy against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa, as well as their antifungal properties against Candida albicans and Aspergillus niger. The results of the experiments indicated that the metal complexes displayed notable antimicrobial effects.

An experimental and comparative study on passive and active PCM cooling of a battery with/out copper mesh and investigation of PCM mixtures

The carbon emission contribution to global warming accelerated both research on and transition to electric vehicles (EVs). Drivers demand high power, fast acceleration and less charging times. All these demands require high C rate charging/discharging demands from batteries. The rate of heat generation is exponentially proportional to C rates which decreases battery lifetime and may lead to thermal runaway. However, a battery thermal management system decreases thermal runaway risk and decelerates battery degradation via controlling battery temperature. In this paper, we first document the thermal conductivity enhancement via copper foam into phase change material (PCM) domain to uncover their possible use in EV thermal management applications. Maximum 15.93 times increment is achieved with a specific copper foam. Then, physical properties and behaviors of distinct PCM mixtures are documented. Homogeneity of mixtures is associated with the chemistry of PCMs and the mixture melting point is proportional to the volume weighted average of melting temperatures. The results document that the PCM with relatively lower melting point is beneficial when end of discharge temperatures considered, except for high discharge rate of 2C. Temperature uniformity across the battery increases with relatively higher melting point PCM. Experiments also document that the amount of PCM volume lost via insertion of copper foam yields higher end of discharge temperatures. Overall, both PCM and copper foam enhances temperature homogeneity and their benefit becomes more sensible during drive cycles relative to continuous charge/discharge use cases.

Enhanced Stability of Melt-Processable Organic-Inorganic Hybrid Manganese Halides for X-Ray Imaging.

Mn-based metal halides scintillators with high photoluminescence quantum yield (PLQY) have recently emerged as promising large-size candidates for X-ray imaging but still remains as difficult challenge in stability and high processing temperatures. Here, three manganese halides are designed by introducing branched chains into organic cations and extending the carbon chains, namely (i-PrTPP)2MnBr4, (i-BuTPP)2MnBr4 and (i-AmTPP)2MnBr4, successfully lowered the melting point of manganese halides to 120.2 °C. Three materials show striking light yields of 59000, 40000, and 52000 photons MeV-1, respectively. The lowest detection limits are 42.30, 50.92, and 45.71 nGy s-1, respectively. Meanwhile, compared to their counterparts with linear carbon chains, the introduction of branched chains has significantly enhanced the stability of the scintillators in the glass state. A transparent glass has been prepared using a melt-quenching method, which exhibited 80% transmittance at 400-700nm. The glass is utilized for X-ray imaging, achieving a high spatial resolution up to 46.6 lp mm-1. This result provides a new approach to enhancing the performance of such scintillator materials.

Thermal analysis and modeling of phase equilibria in the NaCl–NaBr–Na2WO4 system

The phase complex of a three-component system of sodium chlorides, bromides and tungstates was studied for the first time using experimental and theoretical methods. It was found that the liquidus surface of the system consists of the crystallization fields of NaBr, Na2WO4, Na3ClWO4 compounds and NaClxBr1–x solid solutions. The differential thermal method of physico-chemical analysis (DTA) revealed the compositions and melting points of eutectic in the quasi–binary and three–component systems NaBr–Na3ClWO4 and NaCl–NaBr–Na2WO4, respectively. To establish the nature of the physico-chemical interaction in the system, three compositions were studied in the secondary triangle NaCl–NaBr–Na3ClWO4 by the DTA method, thermal effects of tertiary crystallization were not recorded on the DTA curves of these compositions, which is proof of the absence of a non-invariant composition in the NaCl–NaBr–Na3ClWO4 simplex. To determine the composition and melting point of the nonvariant composition located in the NaBr–Na2WO4–Na3ClWO4 simplex, a polythermal section located in the field of crystallization of sodium bromide and a nonvariant section emerging from the crystallization pole of sodium bromide passing through the point of joint crystallization of sodium chloride and the compound, with a constant decrease in the content of sodium bromide in the studied compositions before the onset of non-invariant crystallization process. The composition of the three-component eutectic of ED in molar percentages, crystallizing at 560оC with the following component content, has been determined: 7.5% NaCl; 38.5% NaBr; 54% Na2WO4. Based on data on the melting temperatures of the initial salts, compositions and crystallization temperatures of two- and three-component systems, a 3D-model of the “composition–temperature” phase complex in the temperature range 500–700оC was formed using theoretical methods. On the basis of the model, the isotherms of the liquidus surface and the T–x diagram of the polythermal section for which experimental studies were conducted was constructed. Also, as an example of using a 3D-model, the composition of the equilibrium phases released during cooling of an arbitrarily selected figurative point in the temperature range from 700 to 500оC. was calculated.

Nanoimprinting of Crosslinked Polyurethane / Polycaprolactone Blends: Scratch Recovery of Surface Topographies.

Scratch recovery of micro-nano-patterned polymer surfaces extends the service life of products that require tunable surface properties and contributes to more sustainable development. Scratch recovery has been widely studied in bulk and 4D-printed polymers via intrinsic self-healing mechanisms. Existing studies on self-healing of micro/nano-scale polymeric surfaces are limited to the recovery of controlled tensile or compressive strain. Scratch recovery requires material transport to close the gap created by a scratch. Here, for the first time, scratch recovery of thermally nanoimprinted polymer surfaces in a heterogeneous polymer is reported. A blend of Polyurethane (TPU) and poly(caprolactone) (PCL) with selectively crosslinked TPU imparts shape-memory properties, and the uncrosslinked PCL retains chain mobility for molecular diffusion during scratch recovery. Scratch recovery of nanoimprinted micro-pillars has been achieved spontaneously and completely by heat and without any pressure input. The healing temperature is determined to be the melting point of PCL at 60°C. Rapid recovery is also achieved at 60 s with complete closure of scratch width of 5µm and topography recovery of the nanoimprinted micro-pillars.

Examining the Influence of Silver(I) Ion Coordination Environment in Ionic Liquids on Olefin-Paraffin Separations using Inverse Gas Chromatography.

Silver(I) ions (Ag+) undergo selective π-complexation with olefins and have been employed as separation media for the isolation of olefins from structurally similar paraffins. Ionic liquids (ILs) possess minimal vapor pressures, exceptional thermal stabilities, low melting points, as well as provide a favorable environment for π-complexation between Ag+ ions and olefins. The development of molecular drivers capable of highly selective olefin/paraffin separation systems with Ag+-containing ILs necessitates a comprehensive understanding of all factors that affect olefin solubility and selectivity. This study examines how coordinating different ligand species to Ag+ ions produces separation media with varying interaction strengths to olefins. Four coordination compounds, (4,4'-dimethyl-2,2'-bipyridine)silver(I) bis[(trifluoromethyl)sulfonyl]imide ([Ag+(DMBP)][NTf2-]), bis(pyridine)silver(I) [NTf2-] ([Ag+(Py)2][NTf2-]), bis(2,6-lutidine)silver(I) [NTf2-] ([Ag+(Lut)2][NTf2-]), and (triphenylphosphine)silver(I) [NTf2-] ([Ag+(PPh3)][NTf2-]) were dissolved in the 1-decyl-3-methylimidazolium [NTf2-] ([DMIM+][NTf2-]) IL and employed as stationary phases for inverse gas chromatography. Ligand coordination to the Ag+ ion was observed to modulate interactions of unsaturated hydrocarbons. The [Ag+(Py)2][NTf2-] complex offered the greatest olefin retention among the coordination complexes reaching 54% of the 1-octene retention factor of the uncoordinated [Ag+][NTf2-]. Hydrogen (H2) exposure studies showed ligand-dependent rates of reduction from Ag+ ion to elemental silver (Ag0). The [Ag+(PPh3)][NTf2-] complex exhibited superior stability, compared to the neat [Ag+][NTf2-] salt, reducing the retention factor of 1-octene by 15.3% and 19.4%, respectively, after 200 h of H2 exposure at 70 °C. The results from this study show that coordination complexes with Ag+ ions are useful in highly selective and efficient petroleum processing systems.

Analysis of differential scanning calorimetry data for aged plutonium.

Differential scanning calorimetry data for samples of a 52 year old plutonium alloy with 3.3 at. % Ga that were heated beyond the melting point is analyzed using transition state theory to find activation energies for the δ to ɛ and ɛ to liquid phase transitions. A Bayesian statistical method involving a Gaussian process model is used to find mean values and confidence intervals for the activation energies. The activation energy for the δ to ɛ phase transition increases by 3.3 ± 3.8% per decade, relative to the case when all age related plutonium lattice point defects have been removed through annealing. The corresponding increase in activation energy for the ɛ to liquid transition is shown to be 7.1 ± 1.8% per decade. It is postulated that the change in activation energy with age for both phase transitions is caused, in part, by the accumulation of the same type of lattice point defects associated with the observed increase in elastic bulk modulus over time.

Numerical Analysis of a Two-Layer PCM Based Battery Thermal Management System for Different Material Properties

The design and numerical analysis of the two-layer PCM (Phase Change Material)-based thermal management system for a 18650-type lithium-ion battery have been performed. In relation to simulation, the coefficient of thermal conductivity and melting temperature of the first layer of PCMs are varied. Other parameters are made identical to that of the next layer's parameters in order that the generation of two different layers of PCMs can be attained: PCM-1 and PCM-2. To obtain a more realistic approach in the numerical analysis, the battery thermal model was created in the COMSOL-MATLAB interface using the experimental internal resistance data obtained for 18650 type Li-ion batteries in the literature. While a cheaper and more accessible material with a thermal conductivity of 0.2 W/mK and a melting point of 50 °C was used in the PCM-2 layer, the thermal conductivity was changed to 0.2; 1 and 5 W/mK in the PCM-1 layer; and the melting point was changed to 30, 40 and 50 °C. In this way, for PCM layers with different thickness (tpcm), the system was optimized at two different discharge rates, 5C and 7C. As a result of the numerical analysis, it was determined that the optimum tpcm, kpcm,1 and Tm values for the 5C discharge rate were 2 mm, 0.2 W/mK and 40 °C, respectively; and the optimum tpcm, kpcm,1 and Tm values for the 7C discharge rate were 4 mm, 5 W/mK and 40 °C, respectively.

Study of mechanical and thermophysical properties of Ni3Ti

Abstract This research assesses the thermophysical and ultrasonic characteristics of the intermetallic compound Ni3Ti, which has a hexagonal crystalline structure. The selected material exhibits many noteworthy characteristics, including the shape memory effect, a high melting point, extremely elastic qualities, etc. The Lennard-Jones potential model has been used to calculate the higher-order elastic constants. The mechanical properties of the material, which provide details regarding its stability and intrinsic qualities, are computed using the second-order elastic constants. Additionally, we have computed the thermal conductivity at 300 K, specific heat, ultrasonic velocities, and Debye temperature. Ultimately, the ultrasonic attenuation is determined using all of the available parameters. The obtained results agree with the data available in the literature.

Predicting potential hard materials in Nb[sbnd]B ternary boride: First-principles calculations

To identify potential superhard materials, we conducted a comprehensive theoretical investigation of the thermodynamic and kinetic stability, mechanical properties, electronic structure, Debye temperatures and melting point of sixteen ternary transition metal borides NbTMBx (x = 1, 2, 4 and TM = Ti, V, Fe, Co, Ni, Zr, Ru, Hf, W, Os) using first-principles methods. Our findings indicate that, with the exception of NbFeB, NbRuB, and NbWB, all other borides exhibit both thermodynamic and kinetic stability. Notably, NbTiB4, NbVB4, NbZrB4 and NbHfB4 demonstrate superior hardness and enhanced resistance to deformation, with NbTiB4 showing an impressive hardness value of 40.84 GPa, positioning it as a promising candidate for superhard materials. Both NbVB4 and NbTiB4 have very high Debye temperatures and melting points and can be used in high temperature environments. We further explored the mechanical properties of NbTiB4 at elevated temperatures by employing a combination of first-principles and quasi-static methods. Our analysis reveals that the elastic constants and moduli of NbTiB4 decrease with increasing temperature. Additionally, bonding analysis indicates that all NbB ternary borides exhibit hybridization involving metallic, ionic, and covalent interactions, resulting in the formation of exceptionally strong covalent bonds between boron atoms.

Solid Forms of Bio-Based Monomer Salts for Polyamide 512 and Their Effect on Polymer Properties.

Polyamides' properties are greatly influenced by the polymerization process and the type of feedstock used. The solid forms of nylon salts play a significant role in determining the final characteristics of the material. This study focuses on the long-chain bio-nylon 512. Firstly, we systematically investigated the possible solid forms of the nylon 512 salt, including crystal forms and morphologies, by massive experimental screening, single-crystal X-ray diffraction, Hirshfeld surface analysis, and TG-DSC measurements. The regulation and control of the various solid forms were achieved through solid-state transformations (SSTs) and solution-mediated phase transformations (SMPTs). Our findings shows that the nylon 512 salt exists in two crystal forms (anhydrate and dihydrate) and four morphologies (needle-like, plate-like, rod-like, and massive block crystal). Many factors will influence the formation of these solid forms, such as water activity, temperature, solvent, and ultrasonic physical fields. We can choose the right factors to regulate this as needed. On this basis, we studied the effects of different solid forms (crystal forms and morphologies) on the properties of the resulting polyamides prepared using direct solid-state polymerization (DSSP). The solid form of the salt had many effects on the polymer, including its structure, melting point, and mechanical properties. The polyamide obtained through DSSP of the anhydrate salt exhibited a higher melting point (204.22 °C) and greater elastic modulus (3.366 GPa) compared to that of the dihydrate salt, especially for the anhydrate salt of plate-like crystals.

Synthesis, Characterization and Antimicrobial Activity of Mixed Antibiotic-Vitamin Metal Complexes Involving Metronidazole and Vitamin B1 (Thiamine)

Antimicrobial resistance (AMR) poses a critical threat to global health, making it imperative to develop novel therapeutic strategies. This study focuses on the synthesis and characterization of mixed antibiotic-vitamin metal complexes involving metronidazole and vitamin B1. Metal complexes, known for their unique structural properties, were synthesized with Nickel, Zinc, and Iron salts to enhance the biological efficacy of the parent antibiotics. These complexes were analyzed using various physicochemical methods, including ultraviolet-visible and infrared spectroscopy, and were evaluated for their solubility, elemental composition, and melting points. The antimicrobial activity of the synthesized complexes was tested against bacterial strains such as Streptococcus feacalis, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus, as well as fungal strains like Aspergillus niger and Candida albicans. The results demonstrated that the metal complexes exhibited enhanced antibacterial and antifungal properties compared to the free ligands. Specifically, the zinc and nickel complexes showed significant inhibition against Klebsiella pneumoniae and Aspergillus niger, respectively. This study highlights the potential of metal complexes as promising agents to combat AMR, providing a foundation for future research into drug development and clinical applications.

Enzymatic interesterification of perilla seed oil and palm stearin: A sustainable approach to develop a novel zero-trans-fat margarine rich in omega-3 fatty acids.

The study focuses on developing a novel perilla seed oil (PeO)-based polyunsaturated fatty acid-rich margarine fat analogue using enzymatic interesterification. PeO is a rich source of omega-3 fatty acids, however, has limited application due to susceptibility to oxidative and thermal degradation. Moreover, low consumption of omega-3 fatty acids in modern diets serves as a major cause for increased prevalence of cardiovascular diseases. The stability of such oils can be improved by techniques like blending and interesterification. However, blending lacks uniformity, which can be overcome by interesterification. The process conditions, namely, enzyme load, temperature, substrate molar ratio, and reaction time, were systematically optimized using response surface methodology. The optimized interesterified fat was characterized for fatty acid and triacylglyceride (TAG) composition. The physicochemical and functional properties, along with oxidative stability, were also evaluated to determine its overall quality. The structured lipid with zero trans and low saturated fat was developed with 50:50 substrate molar ratio of PeO and palm stearin at 54°C within 5.4h at 6.2% w/w concentration of TLIM enzyme. It exhibited 23.8% degree of interesterification, 435.5g hardness, and 33°C slip melting point. The TAG profile of the resulting fat was significantly modified with increased triunsaturated TAGs like LnLnLn and LnLnL but reduced trisaturated TAGs like PPP. The interesterification process lowered tocopherol composition by 3%. The acid, peroxide, IP (Induction Period), and p-anisidine values of PeO significantly enhanced. The thermal behavior of the developed fat was also modified. The textural properties of margarine developed from optimized fat were comparable to commercial margarine, revealing the application of PeO in healthy margarine formulation.

Beef tallow/high oleic sunflower oil shortenings produced by chemical interesterification optimized by response surface methodology (RSM): Effect of processing conditions on physical properties

AbstractResponse surface methodology (RSM) was used to obtain two shortenings (IEA and IEB) by chemical interesterification (CI) of beef tallow (BT) and high oleic sunflower oil (HOSFO) with melting points of 35.5°C and 38.5°C, higher OOO and SOO contents, and lower PPP, SOS, POS, and POP percentages than BT. The maximum percentage of HOSFO in the formulations and the optimum time, temperature, and catalyst concentrations to achieve the desired physicochemical properties for the shortenings were determined from the model. The shortenings were characterized, and the effects of processing and storage conditions were explored. HPLC/MS analysis showed that the mono and di‐unsaturated triacylglycerols (TAGs) had unsaturated fatty acids at the sn‐2 position. The changes in chemical composition due to the interesterification process were mostly differences in percentages more than in the type of TAGs present. IEA and IEB showed profiles of solid fat content versus temperature and G' values similar to those reported for soft and firm margarine, respectively. Under static cooling conditions, for BT, BA, BB, and IEB, the α‐form was the main polymorph, whereas the β′‐tendency increased with increasing temperature and slow cooling rate. IEA crystallized in the β′‐form between 20 and 32°C. Under dynamic cooling conditions, nucleation was impeded at fast cooling rate and promoted at slow rate as evidenced by induction times of crystallization. Interesterification decreased the MP, increased the β′ tendency that lasted at least 8 months at 25°C, and improved the nutritional value of shortening making them suitable as trans‐fat alternatives.

Nonstoichiometry Promoted Solventless Recrystallization of a Thick and Compact CsPbBr3 Film for Real-Time Dynamic X-Ray Imaging.

Inorganic CsPbBr3 perovskite emerges as a promising material for the development of next-generation X-ray detectors. However, the formation of a high-quality thick film of CsPbBr3 has been challenging due to the low solubility of its precursor and its high melting point. To address this limitation, a nonstoichiometry approach is taken that allows lower-temperature crystallization of the target perovskite under the solventless condition. This approach capitalizes on the presence of excess volatile PbBr2 within the CsPbBr3 film, which induces melting point depression and promotes recrystallization of CsPbBr3 at a temperature much lower than its melting point concomitant with the escape of PbBr2. Consequently, thick and compact films of CsPbBr3 are formed with grains ten times larger than those in the pristine films. The resulting X-ray detector exhibits a remarkable sensitivity of 4.2 × 104 µC Gyair -1 cm-2 and a low detection limit of 136 nGyair s-1, along with exceptional operational stability. Notably, the CsPbBr3-based flat-panel detector achieves a high resolution of 0.65 lp pix-1 and the first demonstration of real-time dynamic X-ray imaging for perovskite-based devices.