Lower Temperature Research Articles

Research on Support Structure of Rectangular Cryogenic Infrared Lens with Large Aperture

This paper presents the design and optimization of a composite flexible support structure aimed at addressing the challenges associated with maintaining the positional accuracy and surface integrity of large-aperture cryogenic infrared lenses with long focal lengths. The primary objective of the structure is to maintain precise lens alignment while preserving the surface shape under operational conditions. The design complexities and underlying principles of the flexible support structure are systematically explored. A mechanical model of the flexible support structure was derived based on its structural characteristics, and the equilibrium equation was established to ensure the lens meets thermal deformation requirements in various directions. Optimization of key design parameters was conducted for a lens operating at 200 K, measuring 304 mm × 230 mm. The gravitational deformation of the optimized lens exhibited a root mean square (RMS) surface accuracy of 7.72 nm in the X direction, 7.08 nm in the Y direction, and 9.60 nm in the Z direction for lens surface 1. For lens surface 2, RMS values were 8.62 nm in the X direction, 8.41 nm in the Y direction, and 9.64 nm in the Z direction. At 200 K and lower temperatures, the RMS values of lens surfaces 1 and 2 were 2.41 nm and 2.74 nm, respectively, with a first-order mode frequency of 143.37 Hz.

Ecological conditions of vineyards and the polymorphism of Saccharomyces cerevisiae strains as a prerequisite of terroir identification

Aim. The aim of the study was to assess whether the ecological conditions for vineyards and the phylogenetic analysis of Saccharomyces cerevisiae wine yeast strains isolated from several locations in the Odesa and Mykolayiv regions could be used for terroir identification. Methods. The study employed microbiological, analytical, expedition, cartographic, and comparative assessment methods. Phylogenetic analysis was conducted using the MEGA software program, and VIN-CAD-UKR software was used for the vineyard cadastre and the ampelecological characteristics data management. Results. The study highlighted differences in the ecological conditions of vineyards in the Odesa and Mykolayiv regions and within the Tairovo and Izmail territorial communities in the Odesa region, focusing on soil and microclimatic characteristics. Saccharomyces cerevisiae strains isolated in 2012 and 2013, years with varying weather conditions in temperature and precipitation, were primarily clustered by the year of isolation. Two notable exceptions included a strain isolated from the Isabela variety belonging to a hybrid group (direct producer, contrary to other varieties, which mainly represent Vitis vinifera or its hybrids with Vitis riparia, Vitis amurensis, Vitis berlandieri) and a strain isolated from the Odesa Black variety inoculated at the beginning of fermentation with a commercial strain of wine yeast. The 2013 isolates, collected under conditions of higher precipitation and lower temperature in the first half of the growing season, showed a more differentiated clustering pattern, with two strains isolated from the Sukholymansky White variety forming a distinct cluster, while the rest grouped together, irrespective of the region, formed of isolation. Conclusions. Phylogenetic analysis of 64 strains of Saccharomyces cerevisiae isolated from 36 technical grape varieties based on the ITS1_5.8S_ITS2 nucleotide sequence demonstrated that the year of isolation (reflecting agroclimatic factors) was the primary influence on sample clustering. These factors, as components of the ecological conditions of terroir, form the foundation for terroir identification.

Effects of Red Vinasse on Physicochemical Qualities of Blue Round Scad (Decapterus maruadsi) During Storage, and Shelf Life Prediction

A fish processed with red vinasse is a type of Fujian cuisine with regional characteristics. In order to monitor the effect of red vinasse on storage quality and shelf life of blue round scad (Decapterus maruadsi) during storage, the changes in fat content, thiobarbituric acid reactive substances (TBARS), composition of polyunsaturated fatty acids (PUFAs), pH value, texture, and sensory quality were studied at different storage temperatures (4 °C, 25 °C, and 37 °C). By analyzing the correlation between changes in sensory qualities and physical and chemical indexes, a first-order kinetic model and the Arrhenius equation were used to build a shelf-life prediction model for blue round scad during storage. The results showed that processing with red vinasse can significantly reduce the malondialdehyde (MDA) production and the decrease in PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (p < 0.05) during storage. Based on partial least squares regression (PLSR), the storage temperature and time have a significant impact on the PUFA composition in blue round scad, which changed less when the samples were stored at 4 °C and 25 °C, and they had better nutritional composition of fatty acids at lower temperatures. Among the PUFAs, DHA (C22:6n-3) and EPA (C20:5n-3) had higher relative contents and significantly decreased during storage (p < 0.05). Additionally, the processing with red vinasse can slow down the increase in total volatile basic nitrogen (TVB-N) value and pH of blue round scad, maintain the appropriate hardness, elasticity, cohesion and chewability, and improve the overall sensory quality of the fish. In addition, according to the results of model prediction based on TBARS value, the storage shelf life of blue round scad with red vinasse added was 55 d, 2.7 d and 28 h at 4 °C, 25 °C and 37 °C, respectively. The accuracy of the forecast model was high, and the relative errors of the measured values and predicted values were less than 10%. Thus, it not only provided a theoretical basis for the processing and application of red vinasse to Chinese traditional food, but also provided innovative ideas for the safe storage and high-value utilization of blue round scad.

Structural Insights into Cold-Active Lipase from Glaciozyma antarctica PI12: Alphafold2 Prediction and Molecular Dynamics Simulation.

Cold-active enzymes have recently gained popularity because of their high activity at lower temperatures than their mesophilic and thermophilic counterparts, enabling them to withstand harsh reaction conditions and enhance industrial processes. Cold-active lipases are enzymes produced by psychrophiles that live and thrive in extremely cold conditions. Cold-active lipase applications are now growing in the detergency, synthesis of fine chemicals, food processing, bioremediation, and pharmaceutical industries. The cold adaptation mechanisms exhibited by these enzymes are yet to be fully understood. Using phylogenetic analysis, and advanced deep learning-based protein structure prediction tool Alphafold2, we identified an evolutionary processes in which a conserved cold-active-like motif is presence in a distinct subclade of the tree and further predicted and simulated the three-dimensional structure of a putative cold-active lipase with the cold active motif, Glalip03, from Glaciozyma antarctica PI12. Molecular dynamics at low temperatures have revealed global stability over a wide range of temperatures, flexibility, and the ability to cope with changes in water and solvent entropy. Therefore, the knowledge we uncover here will be crucial for future research into how these low-temperature-adapted enzymes maintain their overall flexibility and function at lower temperatures.

Structural modification of high carbon Co−Cr−Mo alloy via chemical etching to enhance hydroxyapatite coating performance

AbstractNumerous papers have been reported on surface treatment of metallic implant to facilitate positive interaction between the implant and hard tissue interface. In this paper, surface treatment such as chemical etching was done on the biomedical grade cobalt‐based alloy prior to hydroxyapatite coating deposition to enhance its biocompatibility. The objective is to investigate which temperature possesses the positive effect in adhesion strength of hydroxyapatite coating without detrimental the surface hardness. Observation showed that acid etched at the highest temperature (80 °C) has successfully roughen the substrate surface from 0.168 μm ±0.1 μm to 1.383 μm ±0.2 μm. Vickers hardness measurement on surface treated at 80 °C exhibit an increment of surface hardness which is about 39 % compared to surface treated at lower temperature. The highest thickness of hydroxyapatite coating layer (~57 μm) was evidently formed on the substrate etched at 80 °C with minimal cracks and no delamination. This phenomenon happened due to chemical reaction were rigorously attack on the substrate surface have provide more micro‐pits, pores and deeper craters that trap more efficiently of hydroxyapatite particles for thicker and dense coating formation. It is worth to note that too long acid soaking will also detrimental the material properties.

Tensile strain-induced disorder and weak localization in SrRuO3 thin films on (100) KTaO3 substrates

Abstract SrRuO3 (SRO) thin (∼12 nm) films have been grown on KTaO3 (001) substrates by RF magnetron sputtering. The as-prepared films are under enormous in-plane tensile strain, which corresponds to the elastic energy of ∼1.5 MJ. Annealing in oxygen at 900 °C for 6 h relaxes strain, partially lowering the elastic energy. The surface topography shows a transition from granularity as the Ar+O2 pressure increases from 5 mTorr to 200 mTorr, with a simultaneous change in the average surface roughness from 4 nm to 0.8 nm. Annealing transforms the topography to island-type and enhances surface roughness. The films deposited at 5 mTorr are semiconducting, and annealing further enhances the resistivity. The ρ-T of films grown at 200 mTorr shows a metallic behavior with an inflection in the ρ-T at TC ∼ 150 K, FM transition. The low-temperature resistivity upturn shows the disordered nature of these films. The eq. ρ T = 1 σ 0 + a T 1 2 + a 1 T p 2 + b T α (p = 2 & α = 2) describes the transport behavior from 2 K to 300 K of 5 mTorr deposited films. In the 200 mTorr deposited film, the above eq. is valid at T < 95 K with p = 2 and α = 1.5. At TC < T ≤ 300 K, the ρ-T follows eq. ρ T = ρ 0 + ρ 1 T α with α = 1.3 and 1.5 for the as-grown and annealed films. The lower temperature ρ-T upturn appears to have contributions from the disorder-enhanced renormalized e-e interaction (REEI) and weak localization (WL) effects. The magnetoresistance behavior supports a substantial WL effect in the films grown at 200 mTorr. Our results establish a strong correlation between the nature of strain, surface topography, and carrier transport mechanisms.

Synthesis and Mechanistic Study of Naphthalimide Derivative Formation via Cu-Mediated Ullmann-Type Reactions.

Cu-mediated Ullmann-type coupling reactions are fundamental to organic synthesis, garnering significant academic and industrial interest since their inception. Optimizing reaction parameters, particularly temperature control, is crucial for maximizing efficiency while maintaining high yields. Bidentate ligands, such as amino acids, have demonstrated potential in facilitating these reactions at lower temperatures (<100 °C). This study explores the Cu-catalyzed Ullmann-type coupling of naphthalimide derivatives with amino acid substitutions. Naphthalimide dyes, known for their diverse applications in bioimaging, solar cells, medicine, and sensors, were selected for their potent anticancer properties. The synthesized compounds were characterized by using 1H NMR, ESI-MS, and melting point analyses. Compounds with significant steric hindrance exhibited lower yields, leading to the development of a novel catalytic system employing l-carnosine as a bidentate ligand, which significantly improved yields. Mechanistic insights, derived from density functional theory calculations, identified "L-complex 3" as the most stable and reactive intermediate during oxidative addition to aryl halides. The oxidative addition transition state "OX1-TS" was found to be the most favorable, with a relatively low energy barrier of 6.13 kcal/mol, suggesting that this step, despite being the rate-limiting stage, is energetically accessible. In contrast, reductive elimination was facilitated by a Cu(III) penta-coordinated intermediate, with a barrier of just 8.34 kcal/mol, making it a more straightforward process. Theoretical findings aligned closely with experimental data, reinforcing the oxidative addition/reductive elimination pathway as the operative mechanism for this reaction.

A Special Kind of Interplanetary Coronal Mass Ejections

Abstract It is generally believed that Coronal mass ejections (CMEs) have magnetic flux rope structures because of their helical shapes. However, only about 30-40% of interplanetary CMEs (ICMEs) have a local magnetic flux rope structure. The usually explanations are that the spacecraft only crossed the flank of the ropes and failed to detect the complete magnetic flux rope structure, or some processes destruct these magnetic flux rope structure. Several studies suggest that some ICMEs inherently possess disordered magnetic fields and consequently exhibit no magnetic flux-rope structures. We introduce a special kind of ICMEs. They have low magnetic field magnitude and stable magnetic field direction, relatively fast expansion speed, lower proton temperature and density. Their all three measured magnetic field components are relatively stable. We want to know whether these ICMEs also have magnetic flux rope structures or not. We identified 20 special ICMEs and analyzed their evolution based on their observed characteristics. We took a special ICME as example, which had apparent rope configuration at 1 AU but evolved to a special ICME at 5.4 AU, to illustrated that this kind of ICMEs may come from magnetic clouds (MCs) whose rope structure had been being stretched due to expansion. We inferred that the missing of obvious flux rope structure may be due to the expansion of MCs, not the flank crossing effect. However, more than 50% of the events were associated with dominant x-component of the magnetic filed, which indicates a leg crossing. Therefore, the detection of part of these special ICMEs may also be results of leg crossing effect.

Effect of ambient conditions in friction surfacing

AbstractFriction surfacing (FS) is a solid-state deposition process in which layers are deposited on a substrate surface by frictional heat and severe plastic deformation of a consumable stud material below its melting temperature. Bonding occurs due to accelerated diffusion. The deposition of several layers on top of each other is referred to as multi-layer FS (MLFS), a promising candidate for additive manufacturing (AM) as it offers advantages over fusion-based AM. In this study, the MLFS process for the precipitation-hardenable alloy AA2024 is investigated regarding the influence of environmental process conditions, i.e., preheating of the substrate like other AM processes as well as underwater and room temperature experiments. The influence of ambient conditions on the process behavior, the layer geometries, the microstructure, and the mechanical properties is shown. Preheating the substrate leads to an overall higher process temperature (424.1 °C), resulting in thinner and wider layers, larger grains, an overaged microstructure, and a smooth hardness transition in the MLFS stacks from top (140 HV0.1) to bottom (95 HV0.1). The lower the process temperatures, e.g., for underwater FS (326.5 °C), the thicker and less wide the layers and the smaller the grains. The hardness shows a periodic pattern at the layer interface, which is more pronounced at lower process temperatures, i.e., the hardness values range from 100 HV0.1 to 150 HV0.1.

Superelastic behavior of novel Ni-Ti-Co shape memory alloys for seismic applications

Abstract Ni-Ti-Co is a new shape memory alloy (SMA) that has higher strength and lower superelastic temperature range than traditional binary Ni-Ti SMA. In this paper, the superelastic properties of Ni-Ti-Co bars that are important for seismic applications were studied and compared with those of Ni-Ti bars. The superelastic behavior, strength, strain recovery, low-cycle fatigue characteristics, and fracture strains of Ni-Ti-Co and Ni-Ti SMA with different heat treatment strategies and testing temperatures from -40℃ to 50℃ were investigated with seismic applications in mind. The effect of low-cycle fatigue loading and temperature variation on the superelasticity degradation of Ni-Ti-Co SMA were evaluated. The results showed that the yield strength of Ni-Ti-Co SMA at room temperature was 1.41 ~ 1.74 times that of the Ni-Ti SMA. Ni-Ti-Co SMA exhibited 100% strain recovery when unloaded from 5% strain in a temperature range from -40℃ to room temperature; while at 50℃, a residual strain of 0.6% was observed when unloaded from 5% strain. For comparison, the Ni-Ti SMA lost superelasticity when the temperature was reduced to 0℃. When subjected to low-cycle fatigue loading, the stability of the superelasticity behavior (maintaining yield stress, energy dissipation and strain recovery) of Ni-Ti-Co SMA at -40℃ was better than that at room temperature and 50℃. In particular, the superelasticity of Ni-Ti-Co SMA at -40℃ was even superior to that of the Ni-Ti SMA at 0℃. At -40℃, the Ni-Ti-Co SMA showed no loss in yield stress, damping ratio and recovery strain during the first 100 cycles of fatigue loading. Moreover, from 100th to 471st cycle, at which fracture occurred, the strain recovery of Ni-Ti-Co SMA showed almost no degradation.&amp;#xD;

Role of Metal-Oxide Interfaces in Methanol Decomposition: Reaction of Methanol on CeO2/Ag(111) Inverse Model Catalysts.

Metal-oxide interfaces play a critical role in catalytic processes, such as methanol adsorption and decomposition reactions. In this work, we investigated methanol reactions on the inverse model CeO2/Ag(111) catalyst surfaces, i.e., submonolayer CeO2 films on Ag(111), under ultrahigh vacuum (UHV) conditions to specially address the role of CeO2-Ag interface in the catalytic methanol decomposition reactions. Using scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and synchrotron radiation photoemission spectroscopy (SRPES), we found that, at the submonolayer ceria coverages, the CeO2 nanoislands exhibit a hexagonal CeO2(111) lattice with fully oxidized Ce4+ on Ag(111). At higher ceria coverages, multilayer ceria nanoislands form on the Ag(111) surface instead of a well-ordered film. A combination of temperature-programmed desorption (TPD) and SRPES reveals that methanol adsorbs dissociatively on the CeO2/Ag(111) surfaces at 110 K, resulting in the formation of methoxy groups. These methoxy groups subsequently decompose via two pathways: (i) interaction with lattice oxygen to produce formate species at 230 K, which then decompose to CO, and (ii) direct dehydrogenation of methoxy to formaldehyde. Notably, the surface with submonolayer CeO2 film on Ag(111) demonstrates low-temperature reactivity (440 K) for methoxy dehydrogenation to formaldehyde, which occurs at a much lower temperature, compared to the surface of multilayer CeO2 on Ag(111) surface (530 K). This finding emphasizes that the CeO2-Ag(111) interfaces provide unique active sites for methoxy dehydrogenation reactions.

Validation of livability environmental limits to heat and humidity.

Rising global temperatures, driven by climate change, pose a threat to human health and regional livability. Empirical data and biophysical model derived estimates suggest that the critical environmental limits (CEL) for livability are dependent on ambient temperature and humidity. We use a well-validated, physiology-based, six-cylinder thermoregulatory model (SCTM) to independently derive CELs during sustained minimal, light, and moderate activity across a broad range of ambient temperatures and humidity levels and compare to published data. The activity and environments were considered livable if predicted core temperatures did not reach 38±0.25°C within six hours. The outcomes for minimal activity revealed CELs ranging from 34°C/95% RH to 50°C/5% RH. Corresponding dry heat losses ranged from 14 W·m-2 and -72 W·m-2 (negative = heat gain) and evaporative heat losses ranged from 39 W·m-2 to 104 W·m-2. The wet bulb temperature (Twb) at the CELs ranged from 33.3 to 20.9°C. Activity shifted CELs toward lower temperatures and humidities. Importantly, our predicted CELs largely agree with observed livability CELs from physiology and those from a biophysical model. The physiology-grounded SCTM has utility for assessing the impact of climate change on regional livability.

Two-Step Chemical Vapor Deposition for Fabrication of FAPbI3 Single-Crystal Microsheets with High Exciton Binding Energy.

Hybrid perovskites exhibit highly efficient optoelectronic properties and find widespread applications in areas such as solar cells, light-emitting diodes, photodetectors, and lasers. Here, we report the innovative synthesis of formamidinium lead iodide (FAPbI3) single-crystal microsheets via a two-step chemical vapor deposition (CVD) method. The microsheets exhibit hexagonal and trapezoidal shapes, with hexagonal FAPbI3 growing parallel to the substrate and trapezoidal FAPbI3 growing perpendicular to the substrate. The dominant role of single-exciton recombination in the photoluminescence (PL) of these microsheets is observed, especially pronounced at low temperatures, attributed to the relatively large exciton binding energies of the samples. Calculations reveal exciton binding energies as high as 110.8 meV for hexagonal and 133.3 meV for trapezoidal FAPbI3 single-crystal microsheets, attributed to reduced rotational freedom of the formamidinium (FA) ions. Further investigation into low-temperature phase transitions indicates lower transition temperatures (around 100 K) for these microsheets, suggesting reduced FA ion rotational freedom and consequently higher exciton binding energies.

Computational Investigation of the Operating Mechanism of the Ranque–Hilsch Vortex Tube

Abstract The Ranque–Hilsch vortex tube is a device that splits an incoming flow into two outgoing streams, but with the peculiar property that one stream exits at a lower total temperature than the incoming flow and the other at a higher total temperature. This temperature separation is accomplished without any moving parts, electronics or external power supplied to the device. Despite the passage of nearly a century since discovery of the effect, there remains a dearth of understanding regarding the mechanism responsible for the phenomenon. In fact, the literature contains competing theories with little evidence providing support. A promising technique to discern the responsible mechanisms for the energy transfer from the ultimately cold stream to the ultimately hot stream is to define a stream tube in a computational simulation of the flow that propagates upstream from the exits such that the stream tube interface separates the hot flow from the cold flow. In this article, we apply this method to a three-dimensional, full-volume analysis of the flow within a vortex tube using a computational simulation that was thoroughly validated against experiments on a physical replica of the computational geometry. In this novel study, the integral form of the energy equation was used to quantify all forms of the energy transfer within the vortex tube. The results demonstrate that the phenomenon of temperature separation is attributable primarily to viscous work in the radial direction due to the circumferential flow, with a lesser contribution from heat transfer in the radial direction.

Nanodomains and Their Temperature Dependence in a Phosphonium-Based Ionic Liquid: A Single-Molecule Tracking Study.

Ionic liquids (ILs) exhibit a unique nanoscale structure (i.e., nanodomains) characterized by their organization into distinct domains. We present evidence of nanodomains in trihexyl(tetradecyl)phosphonium chloride, [P66614][Cl], using single-molecule tracking (SMT) and the maximum entropy method (MEM) to analyze single-molecule trajectories. The diffusion properties of ATTO 647N were assessed as the temperature of [P66614][Cl] increased from 20 °C (4020 cP), 35 °C (1239 cP), 45 °C (599 cP) to 50 °C (439 cP). The MEM analysis revealed a distinct two-population distribution of diffusion coefficients representing nanodomains in [P66614][Cl] at 20 °C (4020 cP). The slow population accounts for 16%, with a diffusion coefficient of 0.104 μm2/s, while the fast population constitutes 84% with a diffusion coefficient of 0.634 μm2/s. Two diffusing populations were also measured for the chemically different probes ATTO 647N, DiD, and Nile Blue chloride in [P66614][Cl] at 20 °C. In contrast, only a single fast population was measured in [P66614][Cl] at 50 °C. At a similar viscosity (640 cP) but a lower temperature of 20 °C, trihexyl(tetradecyl)phosphonium bis[(trifluoromethyl)-sulfonyl]imide, [P66614][NTf2], also showed only a single diffusing population. The elimination of the slow population and the presence of a single diffusing population in [P66614][Cl] as the temperature increases and the viscosity decreases is consistent with liquid-liquid phase separation (LLPS) as a mechanism of nanodomain formation. In addition, the measurement of two diffusing populations for three fluorophores with different chemical structures is also consistent with a physical mechanism, and not a chemical mechanism, for nanodomain formation.

VP28 interacts with PmRab7 irrespective of its nucleotide state.

In shrimp aquaculture, white spot syndrome virus (WSSV) infections severely impact production. Previous research highlighted the crucial role of the Penaeus monodon Rab7 (PmRab7) protein in WSSV entry, specifically its interaction with the viral envelope protein VP28. PmRab7 exists in two conformations: GDP-bound (inactive) and GTP-bound (active). This study, using ELISA and isothermal titration calorimetry (ITC), reveals that the PmRab7-VP28 interaction occurs irrespective of the nucleotide binding state of PmRab7. Comparing the binding affinity between VP28 and different PmRab7 conformations, including wild-type (WT, 22.5 nM), a fast nucleotide exchange (L129F, 128 nM), a GDP-bound form (T22N, 334 nM), and a favorably GTP-bound form (Q67L, 1990 nM), PmRab7-WT exhibits the strongest binding affinity, especially at a lower temperature (25°C). The binding of PmRab7-WT and VP28 in the presence of excess nucleotide (WT with excess GDP, 924 nM, and WT with excess GTP, 826 nM) shows a 2-fold higher binding affinity than in the absence (WT, 1920 nM) indicating that the addition of excess nucleotide for PmRab7-WT enhanced the affinity for VP28. Together, these findings support the potential of PmRab7-WT as a promising therapeutic candidate for WSSV control in shrimp. Furthermore, from an industrial point of view, the ITC platform developed to study the VP28-PmRab7 interactions provides a high-throughput method for screening additives for shrimp feed that can inhibit this interaction.

A highly visible-transparent thermochromic smart window with broadband infrared modulation for all-season energy savings

Abstract Thermochromic smart windows effectively reduce the energy consumption for building through passive light modulation including the transmission of visible (TVis), near-infrared (TNIR), and the emissivity of mid-infrared (εMIR) in response to the ambient temperature change. However, thermochromic windows that maintain high TVis while modulating TNIR and εMIR simultaneously are highly desirable but still challenging. Here, we develop a thermochromic smart window based on a two-way shape memory polymer to enable reversible transformation and achieve TNIR modulation of 44.0% and εMIR modulation of 76.5% while maintaining high TVis (&amp;gt;50%). Compared to traditional windows based on silica glass, this device shows 4°C lower temperature in summer daytime, 2°C higher in winter daytime, and 1°C higher in spring nighttime. It is expected that our device can achieve greater annual energy savings in comparison with commercial glass anywhere in the world and promote the progress of thermochromic windows for energy-efficient buildings.

Design and utilisation of a novel poly imino-phosphorane composite for the effective removal of Pb2+ and Cr3+ ions from contaminated water sources

ABSTRACT This study introduces a novel chitosan-immobilised imino-phosphorane composite (Chi-iph) for the efficient removal of lead (Pb2+) and chromium (Cr3+) from wastewater. The successful synthesis of Chi-iph was confirmed using FT-IR, XPS, BET, EDX, TGA, 1H-NMR, 13C-NMR, EI/MS, and ICP-OES analyses. Various experimental parameters such as pH, equilibrium time, metal concentration, adsorbent dose, temperature, and eluents were optimised to enhance the adsorption performance. At 25°C, with pH values of 5.5 for Pb2+ and 4.5 for Cr3+, an initial concentration of 200 mg/L, and an agitation time of 20 min, the maximum adsorption capacities were 55 mg/g for Pb2+ and 45 mg/g for Cr3+. Kinetic modelling demonstrated that the pseudo-first-order model best predicted the adsorption process, yielding capacities of 56.65 mg/g for Pb2+ and 46.38 mg/g for Cr3+. Isotherm analysis showed that the Langmuir model was a better fit than the Freundlich model, with theoretical capacities of 56.81 mg/g for Pb2+ and 44.64 mg/g for Cr3+. The Dubinin–Radushkevich (D-R) isotherm revealed adsorption energy (E) values of 9.45 kJ/mol for Pb2+ and 8.64 kJ/mol for Cr3+, indicating a chemisorption process. Theoretical saturation capacities (qD) were 56.28 mg/g for Pb2+ and 45.58 mg/g for Cr3+. Temkin isotherm results, with bT values of 9.71 and 8.53 kJ/mol for Pb2+ and Cr3+ respectively, aligned closely with the D-R model, further confirming chemisorption. Thermodynamic studies indicated that the adsorption process is exothermic, spontaneous, and more favourable at lower temperatures. Complete desorption of the heavy metals was achieved using 1 M HNO₃, allowing for efficient metal recovery. In a practical application, the Chi-iph composite removed 11.5 mg/L of Pb2+ and 7.01 mg/L of Cr3+ from contaminated wastewater, demonstrating its potential for environmental remediation. The composite’s performance aligns with WHO and FAO guidelines, making it suitable for treating wastewater before disposal into marine environments.

Study on the Formation and Mechanical Stability of Retained Austenite in Complex Phase Steel with High Formability

Herein, a 1300 MPa grade complex phase steel with high formability (CH) is developed, which is achieved through the formation of cementite during pretreatment and the control of austempering temperature to enhance the stability of retained austenite (RA). Due to the insufficient diffusion of Mn during cementite dissolution, Mn enrichment enhances the mechanical stability of austenite, thereby increasing austenite content at room temperature. As the austempering temperature increases from 340 °C to 400 °C, the RA content increases, but its stability decreases significantly. Compared with the content of RA, its stability is more critical for enhancing plasticity. RA formed at lower austempering temperatures is highly stable, enlarging the strain range of the transformation‐induced plasticity effect and improving material plasticity. The experimental steel achieves optimal plasticity while maintaining strength when overaged at 360 °C. Specifically, the yield strength is 963 MPa, the ultimate tensile strength is 1394 MPa, and the total elongation is 14.0%.

A Numerical Study of the Thermochemical and Aerodynamic States of H2‐intensive Direct Reduction Shaft Furnace

In the urgent pursuit of deep decarbonization, the steel industry has paid significant attention to the hydrogen‐intensive direct reduction process, where the H2‐to‐CO (volume) ratio of feed gas for the shaft furnace (SF) is increased compared to the current level. In this work, the reduction process of iron oxide pellets in the SF is investigated numerically to clarify how the in‐furnace thermochemical and aerodynamic states are affected by increasing hydrogen content, with the goal to provide guidelines for more efficient operations of the unit. Multiscale modeling is conducted to investigate the complicated gas–solid countercurrent reactive flows in the SF where the reduction behavior of an individual iron oxide pellet is described using a three‐interface unreacted shrinking core model. The results show that an increase in the hydrogen content leads to a lower temperature level and hence a deteriorated thermochemical state. It also induces a lower gas pressure drop over the in‐furnace packed bed.