Metallic Behavior Research Articles

Valorization of low heavy metal-accumulating plants through catalytic hydrothermal liquefaction with attapulgite: Product characterization and migration behavior of heavy metals

Harmless treatment of heavy metal-accumulating plants is significant for further development and application of phytoremediation for contaminated soil remediation. In this study, hydrothermal liquefaction (HTL) of low heavy metal-accumulating plants (Jute, Solanum nigrum, and Sorghum) was conducted at different temperatures (280–360 °C) for bio-oil production. Attapulgite and Co/Attapulgite were prepared and tested in HTL process. The maximum bio-oil yield and higher heating value (HHV) was found to be 32.04% and 29.61 MJ/kg from HTL of Solanum nigrum with Co/Attapulgite at 300 °C. The improvement in quality of bio-oil was marked with decreased O/C content (0.26) and newly formed hydrocarbon fraction with the content of 6.24% with Co/Attapulgite catalyst. It was beneficial for immobilization of Mn, Zn and Cr in hydrochar with addition of catalyst. Notably, Mn and Cd were not detected in any bio-oil, and the proportion of Cr in the bio-oil obtained at 360 °C decreased to zero with Co/Attapulgite. XPS and XRD analysis indicated that Mn and Zn existed in the form of Mn3O4, Mn, ZnO and Zn(OH)2 in hydrochar. Finally, potential pathway of heavy metals migration-transformation behaviors during HTL was proposed.

Semi-Quantitative Categorization Method for the Corrosion Behavior of Metals Based on Immersion Test

Corrosion processes are complex in nature and their studies have become an interdisciplinary research field, combining fundamental sciences and engineering. As the quantification of corrosion processes is affected by many variables, standard guidelines to study such phenomena had been developed, such as ASME and ISO, and are broadly used in industry and academics. They describe methods to perform immersion test experiments and to quantify the corrosion rates of metals exposed to corrosive environments, but do not provide any guidelines for post-exposure analysis of the as-obtained corroded samples, which might provide useful information to understand the underlying physicochemical mechanisms of corrosion. This knowledge is useful for selecting optimal construction materials and developing corrosion prevention strategies. In this work, a semi-quantitative categorization method of the corrosion behavior of metals exposed to a corrosive medium based on their mass loss and aspect is presented. For each category, the mathematical aspects of gravimetric measurements of mass change rate and the analytical techniques that can be used for the characterization of materials are discussed. The following method does not intend to replace industrial standards, but to expand them in order to maximize the amount of information that can be extracted from immersion tests.

Localization of overdamped bosonic modes and transport in strange metals

The strange metal phase of correlated electrons materials was described in a recent theory by a model of a Fermi surface coupled a two-dimensional quantum critical bosonic field with a spatially random Yukawa coupling. With the assumption of self-averaging randomness, similar to that in the Sachdev-Ye-Kitaev model, numerous observed properties of a strange metal were obtained for a wide range of intermediate temperatures, including the linear in temperature resistivity. The Harris criterion implies that spatial fluctuations in the local position of the critical point must dominate at lower temperatures. For an [Formula: see text]-component boson with [Formula: see text], we use multiple graphics processing units (GPUs) to compute the real frequency spectrum of the boson propagator in a self-consistent mean-field treatment of the boson self-interactions, but an exact treatment of multiple realizations of the spatial randomness from the random boson mass. We find that Landau damping from the fermions leads to the emergence of the physics of the random transverse-field Ising model at low temperatures, as has been proposed by Hoyos, Kotabage, and Vojta. This regime is controlled by localized overdamped eigenmodes of the bosonic scalar field, also has a resistivity which is nearly linear-in-temperature, and extends into a "quantum critical phase" away from the quantum critical point, as observed in several cuprates. For the [Formula: see text] Ising scalar, the mean-field treatment is not applicable, and so we use Hybrid Monte Carlo simulations running on multiple GPUs; we find a rounded transition and localization physics, with strange metal behavior in an extended region around the transition.

Single [0001]-oriented zinc metal anode enables sustainable zinc batteries

The optimization of crystalline orientation of a Zn metal substrate to expose more Zn(0002) planes has been recognized as an effective strategy in pursuit of highly reversible Zn metal anodes. However, the lattice mismatch between substrate and overgrowth crystals has hampered the epitaxial sustainability of Zn metal. Herein, we discover that the presence of crystal grains deviating from [0001] orientation within a Zn(0002) metal anode leads to the failure of epitaxial mechanism. The electrodeposited [0001]-uniaxial oriented Zn metal anodes with a single (0002) texture fundamentally eliminate the lattice mismatch and achieve ultra-sustainable homoepitaxial growth. Using high-angle angular dark-filed scanning transmission electron microscopy, we elucidate the homoepitaxial growth of the deposited Zn following the “~ABABAB~” arrangement on the Zn(0002) metal from an atomic-level perspective. Such consistently epitaxial behavior of Zn metal retards dendrite formation and enables improved cycling, even in Zn||NH4V4O10 pouch cells, with a high capacity of 220 mAh g−1 for over 450 cycles. The insights gained from this work on the [0001]-oriented Zn metal anode and its persistently homoepitaxial mechanism pave the way for other metal electrodes with high reversibility.

A Review of Sheet Metal Forming Evaluation of Advanced High-Strength Steels (AHSS)

This paper presents a review on the formability evaluation of AHSS, enhancing necking-based failure criteria limitations. Complementary fracture/damage constitutive modeling approaches specifically tailored to formability evaluation, validated through numerical and experimental methods, are also subjects of research. AHSS are widely processed through sheet metal forming processes. Although an excellent choice when lightweight, high-strength, and ductility are critical factors, their multi-phase microstructure accentuates forming challenges. To accurately model forming behavior, necking-based failure criteria as well as direct fracture models require improvements. As a necking-based failure model, the conventional forming limit diagram/curve (FLD/FLC) presents limitations in estimating direct fracture (surface cracks, edge cracks, shear cracks), as well as deformation histories under non-linear strain paths. Thus, significant research efforts are being made towards the development of advanced fracture constitutive models capable of predicting fracture scenarios without necking, which are more frequently observed in the realm of AHSS. Scientific community research is divided into several directions aiming at improving the forming and fracture behavior accuracy of parts subjected to sheet metal forming operations. In this review paper, a comprehensive overview of ductile fracture modeling is presented. Firstly, the limitations of FLD/FLC in modeling fracture behavior in sheet metal forming operations are studied, followed by recent trends in constitutive material modeling. Afterwards, advancements in material characterization methods to cover a broad range of stress states are discussed. Finally, damage and fracture models predicting failure in AHSS are investigated. This review paper supplies relevant information on the current issues the sheet metal forming community is challenged with due to the trend towards AHSS employment in the automotive industry.

Solidification cracking susceptibility and carbide evolution behavior in ERNiMo-2 weld metal: Effect and mechanism of Si content

ERNiMo-2 wire is the matching welding filler metal for the GH3535 alloy, which is prone to occur solidification cracking during welding. Optimizing the composition of ERNiMo-2 wire is an effective way to reduce the welding solidification cracking susceptibility (WSCS) and improve the performance of GH3535 alloy welded joint. In this study, the WSCS of ERNiMo-2 wires with different Si content was evaluated by the trans-varestraint test, and the mechanism of Si affecting the weldability of ERNiMo-2 wire was revealed. The results showed that the solidification cracking temperature range (SCTR) of Si1-Si4 wires with Si content increasing is 102 °C, 123.2 °C, 119.1 °C and 116.3 °C, respectively. The existence of eutectic M2C and M6C in the form of liquid film at the end of solidification leads to partial wetting of the grain boundary, which reduces the binding force of the grain boundary and promotes crack initiation. Low solidification shrinkage, thermal shrinkage, solidification temperature range and a small amount of eutectic liquid in the mushy region make the Si1 wire have the best resistance to solidification cracking. The aforementioned factors increase with Si content, then resulting in the increase of WSCS of Si2. However, the amount and fluidity of eutectic liquid in weld metal increase when the Si content increases to Si3 and Si4, which leads to the occurrence of eutectic backfilling and decrease in WSCS of ERNiMo-2 wire.

Research on long-term migration behaviors of heavy metals after close-distance coal seam backfill mining

The backfill mining of coal-based solid waste in goaf poses a potential risk of heavy metal pollution to the groundwater environment, and the migration behavior of heavy metals differs significantly under the disturbance of backfill mining in close-distance multi-layer coal seams and single-layer coal seams. In this study, a migration model of heavy metals after solid backfilling in the goaf of shallow-buried close-distance thick coal seams was established, and the impact of the overburden damage and the layered distribution of the filling body on the long-term migration behavior of heavy metals were analyzed. The results show that the migration of heavy metals after close-distance coal seam backfill mining exhibits a higher risk of heavy metal pollution. The peak permeability of overburden after close-distance coal seam backfill mining is about 600 × 10−19 m2 higher than that after single-layer coal seam backfill mining. The migration distance of heavy metals in the floor after backfill mining of close-distance coal seams is 7.41 m farther than that of single-layer coal seam backfill mining, and its migration time of heavy metals to the surface is 27 a earlier than that of single-layer coal seam. This research provides theoretical and empirical support for the ecological risk assessment and heavy metal pollution control in close-distance coal seam backfill mining. Environmental ImplicationThe main filling material of close-distance coal seams backfill mining is coal gangue. Heavy metal elements such as Mn and Cr will be released in the underground environment for a long time, and the migration behavior of heavy metal elements will have an impact on the groundwater environment for more than 1000 years. This research provides theoretical and empirical support for the ecological risk assessment of close-distance coal seam backfill mining and the mitigation of heavy metal pollution.

Theoretical investigation of XSnH3 (X: Rb, Cs, and Fr) perovskite hydrides for hydrogen storage application

The current study investigated the structural, mechanical, electronic, and optical properties of new perovskite hydrides XSnH3 (X = Rb, Cs, and Fr) for hydrogen storage applications using a first-principles study with the GGA-PBE approach. The calculated lattice constants form optimized cubic crystal have 4.40 Å, 4.49 Å and 4.53 Å for RbSnH3, CsSnH3, and FrSnH3 hydrides, respectively. These materials were found to be thermodynamically and mechanically stable structures owing to their negative cohesive energy and elastic constants. Additionally, molecular dynamics (MD) calculations were performed to study the thermal stability of the current materials. These results indicate that the considered materials were stable and exhibited no structural deformation. The electronic band structure and density of states confirmed that the current materials exhibit metallic behavior via overlapping of the valence and conduction bands with a zero-energy band gap. It was found these compounds have anisotropic and rigid in nature. The Poisson's ratio, Pugh's ratio (B/G), and Cauchy pressure (CP) values indicate that the current compounds have ionic bonding and brittle behavior. Different optical parameters were calculated for these materials, such as the conductivity, dielectric function, loss energy, refractive index, and adsorption. Interestingly, these optical parameters indicate that XSnH3 is promising for optoelectronic, photonic, and energy storage applications. Finally, the calculated hydrogen storage capacities for RbSnH3, CsSnH3, and FrSnH3 are 1.45 wt%, 1.18 wt %, and 0.87 wt %respectively. These results show that current materials have the potential and promise for hydrogen storage applications, and devices.

Structure–Activity Relationship and Stimuli-Responsiveness Behavior of Metallosupramolecular Polymers

The widespread discourse on the circular economy has fueled a growing demand for polymeric materials characterized by mechanical robustness, sustainability, renewability, and the ability to mend defects. Such materials can be crafted using dynamic covalent bonds, albeit rarely or more efficiently through noncovalent interactions. Metal–ligand interactions, commonly employed by living organisms to adapt to environmental changes, play a pivotal role in this endeavor. Metallosupramolecular polymers (MSPs), formed through the incorporation of metal–ligand interactions, present a versatile platform for tailoring physicochemical properties. This review explores recent advancements in MSPs achieved through the assembly of (macro)monomers via reversible metal–ligand interactions. Various strategies and pathways for synthesizing these materials are discussed, along with their resulting properties. The review delves into the stimuli-responsive behavior of coordination metal–ligand polymers, shedding light on the impact of the core employed in MSPs. Additionally, it examines the influence of parameters such as solvent choice and counter-ions on the supramolecular assemblies. The ability of these materials to adapt their properties in response to changing environmental conditions challenges the traditional goal of creating stable materials, marking a paradigm shift in material design.

An environmentally benign process for effective recovery and solidification of Cr from stainless-steel slag

Stainless-steel slag is a hazardous solid that has caused severe chromium contamination globally. This study proposes an environmentally benign vitrification process for efficient recycling and solidification of Cr from stainless-steel slag using waste copper slag and coal tar residue. The transformation behaviors of heavy metals (Cr, Cu, Pb, Zn) and the Cr toxic leaching mechanism are also determined in this work. The findings indicated that compared with Cu and Fe phases, the Mg(Al,Cr)2O4 and chemically dissolved Cr phases were not easily reduced via coal tar residue, leading to the leaching of highly toxic Cr3+/Cr6+ during the toxicity characteristic leaching procedure (TCLP). Under optimal conditions, 95.56% Cr, 97.71% Fe, and 99.71% Cu could be recovered in the form of high value-added crude stainless-steel, and 99.62% Pb and 99.19% Zn could be enriched in the dust. The furnace slag TCLP result indicated that the leaching concentrations of Cr, Cu, Pb and Zn were 1.82 mg/L, 0.1 mg/L, 0.38 mg/L, and 2.58 mg/L, respectively. More importantly, the concentrations of residual Cr, Cu, Pb and Zn in the furnace slag were only 0.095 wt%, 0.028 wt%, 0.0192 wt%, and 0.011 wt%, respectively. These findings indicate that treated slag can be categorized as general solid waste, minimizing the environmental risks of heavy metals. The results of this study are significant for the sustainable development of the stainless-steel industry and copper metallurgy.

Research on the Impact Behavior of Molten Metal on the Mold Shell in Gravity Casting of Large Titanium alloy Castings

The impact behavior of molten metal on the mold shell in gravity casting of large titanium alloy castings by investment precision castings was studied. The physical and mechanical models of the impact of molten metal on the mold shell during the pouring process were constructed using numerical simulation. The effects of molten metal pouring rate and pouring weight on the maximum impact force of the mold shell were studied. The research results indicated that during the entire pouring process, the impact force of the first molten metal contacting the mold shell was higher than subsequent molten metal. The maximum impact force increased with the increase of pouring rate and pouring weight. The total impact force of the molten metal on the mold shell was composed of the instantaneous impact force converted from instantaneous impulse and itself gravity. The instantaneous impact force of the molten metal that first impacts the mold shell was much greater than its own gravity, while the impact force of the molten metal at the end of pouring was much less than its own gravity. The maximum impact force on the mold shell of a large casting with a pouring weight of 800kg was about three times higher than that of a medium-sized casting with a pouring weight of 80kg.The difference in the total impact force on the mold shell between them mainly comes from the instantaneous impact force converted from instantaneous impulse.

Effect of freeze-thaw frequency plus rainfall on As and Sb metal(loid)s leaching from the solidified/stabilized soil remediated with Fe-based composite agent

The composite agent of ferrous sulfate, fly ash, and calcium lignosulfonate (FFC) can remediate the soil contaminated by As and Sb under cyclic freeze-thaw (F-T) via stabilization/solidification (S/S). However, the impact of high-frequency F-T cycles on the leaching behavior and migration of As and Sb in FFC-treated soils remains unclear. Here the leaching concentrations, heavy metal speciation (Wenzel's method), and Hydrus-1d simulations were investigated. The results showed that FFC effectively maintained the long-term S/S efficiency of arsenic remediation subject to an extended rainfall and freeze-thaw cycles, and stabilized the easily mobile form of As. The short-term S/S effect on Sb in the remediated soils suffering from F-T cycles was demonstrated in the presence of FFC. In a 20-year span, the mobility of Sb was affected by the number of F-T cycles (FT60 > FT20 > FT40 > FT0) in soil with a depth of 100 cm. As leaching progressed, FFC slowed the upward proportion of adsorbed As fractions but converted parts of the residual Sb to the form of crystalline Fe/Al (hydro) oxide. Moreover, the adsorption rate and capacity of As also preceded that of Sb. Long-term curative effects of FFC could be observed for As, but further development of agents capable of remedying Sb under cyclic F-T and long-term rainfall was needed. The predictive results on the migration and leaching behavior of heavy metals in S/S remediated soils may provide new insight into the long-term assessment of S/S under natural conditions.

Copper-Enriched Nanostructured Conductive Thermoelectric Copper(I) Iodide Films Obtained by Chemical Solution Deposition on Flexible Substrates

The objects of our research are flexible thin-film thermoelectric materials with nanostructured CuI layers 0.5–1.0 μm thick, fabricated by the chemical solution method Successive Ionic Layer Adsorption and Reaction (SILAR) on flexible polyethylene terephthalate and polyimide substrates. These cubic γ-CuI films differ from films obtained by other chemical solution methods, such as spin-coating, sputtering, and inject printing, in their low resistivity due to acceptor impurities of sulfur and oxygen introduced into CuI from aqueous precursor solutions during SILAR deposition. Energy barriers at the boundaries of 18–22 nm CuI nanograins and a large number of charge carriers inside the nanograins determine the transport properties in the temperature interval 295–340 K characterized by transitions from semiconductor to metallic behavior with increasing temperature, which are typical of nanostructured degenerate semiconductors. Due to the resistivity of about 0.8 mΩ· m at 310 K and the Seebeck coefficient 101 μV/K, the thermoelectric power factor of the CuI film 1.0 μm thick on the polyimide substrate is 12.3 μW/(m · K2), which corresponds to modern thin-film p-type thermoelectric materials. It confirms the suitability of CuI films obtained by the SILAR method for the fabrication of promising inexpensive non-toxic flexible thermoelectric materials.

Dual quantum spin Hall insulator by density-tuned correlations in TaIrTe4.

The convergence of topology and correlations represents a highly coveted realm in the pursuit of new quantum states of matter1. Introducing electron correlations to a quantum spin Hall (QSH) insulator can lead to the emergence of a fractional topological insulator and other exotic time-reversal-symmetric topological order2-8, not possible in quantum Hall and Chern insulator systems. Here we report a new dual QSH insulator within the intrinsic monolayer crystal of TaIrTe4, arising from the interplay of its single-particle topology and density-tuned electron correlations. At charge neutrality, monolayer TaIrTe4 demonstrates the QSH insulator, manifesting enhanced nonlocal transport and quantized helical edge conductance. After introducing electrons from charge neutrality, TaIrTe4 shows metallic behaviour in onlya small range of charge densities but quickly goes into a new insulating state, entirely unexpected on the basis of the single-particle band structure of TaIrTe4. This insulating state could arise from a strong electronic instability near the van Hove singularities, probably leading to a charge density wave (CDW). Remarkably, within this correlated insulating gap, we observe a resurgence of the QSH state. The observation of helical edge conduction in a CDW gap could bridge spin physics and charge orders. The discovery of a dual QSH insulator introduces a new method for creating topological flat minibands through CDW superlattices, which offer a promising platform for exploring time-reversal-symmetric fractional phases and electromagnetism2-4,9,10.

Hydrogen in metallic alloys ─ embrittlement and enhanced plasticity: a review

Abstract The evolution of ideas concerning the nature of hydrogen embrittlement of engineering metallic materials is described based on a number of the proposed hypotheses and corresponding experiments. The main attention is paid to two of them, namely hydrogen-enhanced decohesion (HEDE) and hydrogen-enhanced localized plasticity (HELP). Recent attempts to interconnect the both models as HELP + HEDE and HELP-mediated HEDE ones are also estimated. A conclusion is made that HELP model is preferential for understanding the entire array of experimental data with a caveat that it is necessary to consider the chemical nature of hydrogen atoms and view them not only as point defects. Based on the studies of hydrogen effect on the atomic interactions in iron, nickel, titanium, and its alloys, it is shown that the electron approach to HELP phenomenon adequately describes two competitive features of hydrogen behavior in metals: increased brittleness and enhanced plasticity. Due to the increase in the concentration of free electrons, hydrogen decreases the elasticity moduli, which causes the crystal lattice to soften. For this reason, the formation of hydrogen atmospheres around the dislocations decreases the start stress of dislocation sources, as well as line tension of emitted dislocations, enhancing thereby their mobility, and weakens repulsion between dislocations in their pile-ups. The range of temperatures and strain rates in which hydrogen embrittlement occurs is controlled by the enthalpies of hydrogen atoms’ diffusion and their binding to dislocations. The resulting consequences for mechanical properties depend on the short-range atomic order, SRO, which inherently occurs in the metallic solid solutions and localizes plastic deformation both in the cases of short-range atomic ordering and of short-range atomic decomposition. Hydrogen enhances slip localization because of its different solubility in the submicrovolumes of short-range decomposed solid solutions. If SRO is absent or not remarkably formed, the hydrogen-increased concentration of free electrons results in enhanced plasticity. Available positive hydrogen effects on the plasticity of titanium β-alloys and austenitic steels are presented and interpreted.

An elastoplastic phase-field model for quasi-static fracture of nickel-based super-alloys

In the present study, an elastoplastic phase-field model of quasi-static fracture in ductile materials is proposed in the variational framework for J2 plasticity with isotropic hardening, which is suitable to describe the quasi-static behavior of metals as investigated in the performed experiments. These contributions include: (1) the free energy functions for coupling elastic response, plastic yielding and damage evolution are established. (2) The new elastic and plastic energy degradation functions are constructed to quantitatively describe the relationship between energy release and phase-field evolution of elastoplastic materials. (3) Damage evolution and plastic yielding criteria are derived. (4) From a numerical point of view, we derive the governing equations and the corresponding weak forms and the overall solution procedure for the phase-field model is given via the use of a return-mapping algorithm. This phase-field model was validated by a series of tensile experiments on Inconel 718 nickel-based super-alloys standard specimens. In order to compare the simulation results with the experimental results more comprehensively, the digital image correlation (DIC) technique is applied to experimentally investigate the specimen deformation information. In addition, to verify the potential of the model to capture complex cracks, we performed Nooru-Mohamed tests. The numerical simulation results are in good agreements with the results of previous experimental work.

Exploration of superconductivity in LK-99 synthesized under different cooling conditions

The claim of superconductivity above room temperature at ambient pressure in Cu-doped lead apatite (LK-99, Pb10-xCux(PO4)6O) has attracted considerable attention. In this paper, we present the results of synthesized LK-99 using a systematic approach based on quenching method variations. A slower cooling rate resulted in an increased LK-99 phase and a decreased Cu2S phase, with the slowest cooling method achieving the highest concentration of the LK-99 phase. Magnetic levitation was observed in certain specimens, with one end adhering to the magnet and the other end floating, which was distinguished from the Meissner effect. The majority of samples synthesized under different conditions exhibited no response to the magnet. The slowest cooled sample exhibited mostly insulating behavior. The samples synthesized in the other conditions had metallic behaviors, which contained a significant amount of Cu2S. No evidence of superconductivity was observed within the temperature range of 4 K–300 K in our samples.

Thermodynamic properties and enhancement of diamagnetism in nitrogen doped lutetium hydride synthesized at high pressure

Nitrogen doped lutetium hydride has drawn global attention in the pursuit of room-temperature superconductivity near ambient pressure and temperature. However, variable synthesis techniques and uncertainty surrounding nitrogen concentration have contributed to extensive debate within the scientific community about this material and its properties. We used a solid-state approach to synthesize nitrogen doped lutetium hydride at high pressure and temperature (HPT) and analyzed the residual starting materials to determine its nitrogen content. High temperature oxide melt solution calorimetry determined the formation enthalpy of LuH1.96N0.02 (LHN) from LuH2 and LuN to be -28.4 ± 11.4 kJ/mol. Magnetic measurements indicated diamagnetism which increased with nitrogen content. Ambient pressure conductivity measurements observed metallic behavior from 5 to 350 K, and the constant and parabolic magnetoresistance changed with increasing temperature. High pressure conductivity measurements revealed that LHN does not exhibit superconductivity up to 26.6 GPa. We compressed LHN in a diamond anvil cell to 13.7 GPa and measured the Raman signal at each step, with no evidence of any phase transition. Despite the absence of superconductivity, a color change from blue to purple to red was observed with increasing pressure. Thus, our findings confirm the thermodynamic stability of LHN, do not support superconductivity, and provide insights into the origins of its diamagnetism.

The impact of recycling polyaluminium chloride and anionic polyacrylamide water treatment residuals on heavy metal adsorption in soils: implications for stormwater bioretention systems.

Despite the high adsorption capacity of polyaluminum chloride and anionic polyacrylamide water treatment residuals (PAC-APAM WTRs) for Pb2+, Cd2+, Cu2+, and Zn2+, their influence on the adsorption behavior of heavy metals in traditional bioretention soil media remains unclear. This study investigated the impact of PAC-APAM WTRs at a 20% weight ratio on the adsorption removal of Pb2+, Cd2+, Cu2+, and Zn2+ in three types of soils. The results demonstrated improved heavy metal adsorption in the presence of PAC-APAM WTRs, with enhanced removal observed at higher pH levels and temperatures. The addition of PAC-APAM WTRs augmented the maximum adsorption capacity for Pb2+ (from 0.98 to 3.98%), Cd2+ (from 0.52 to 10.99%), Cu2+ (from 3.69 to 36.79%), and Zn2+ (from 2.63 to 13.46%). The Langmuir model better described the data in soils with and without PAC-APAM WTRs. The pseudo-second-order model more accurately described the adsorption process, revealing an irreversible chemical process, although qe demonstrated improvement with the addition of PAC-APAM WTRs. This study affirms the potential of PAC-APAM WTRs as an amendment for mitigating heavy metal pollution in stormwater bioretention systems. Further exploration of the engineering application of PAC-APAM WTRs, particularly in field conditions for the removal of dissolved heavy metals, is recommended.

Effect of Sc on the Wettability of ER5356 Welding Wires and the Porosity of Deposited Metal.

In this study, Al-Mg and Al-Mg-Sc ER5356 welding wires were adopted, and the effects of the Sc element on the wetting behavior of the molten metal and the porosity of the deposited metal were investigated. Al-Mg-Sc and Al-Mg welding wires exhibit wetting angles of 17.2 and 12.4°, respectively, and their porosities of deposited metal were 0.885 and 0.454%, respectively. Adding the Sc element to ER5356 welding wires reduced the surface tension and then increased the pore difference pressure, wettability, and spreadability of the molten pool, which is beneficial for pore overflow. Besides, adding Sc elements could increase the molten droplet size and the metallic vapor recoil for the ER5356 wire and then stabilize droplet transfer.