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Spontaneous crystallization of metals under extreme conditions is a unique phenomenon occurring under far-from-equilibrium conditions that could enable the development of revolutionary and disruptive metastable metals with unusual properties. In this work, the formation of the hexagonal close-packed nickel (hcp-Ni) metastable phase during spontaneous crystallization is studied using non-equilibrium molecular dynamics (MD) simulations, with the goal of maximizing the fraction of this metastable phase in the final state. We employ Bayesian optimization (BO) with the Gaussian processes (GPs) regression as the surrogate model to maximize the hcp-Ni phase fraction, where temperature and pressure are control variables. MD simulations provide data for training the GP model, which is then used with BO to predict the next simulation condition. Such BO-guided active learning leads to a maximum hcp-Ni fraction of 43.38% in the final crystallized phase within 40 iterations when a face-centered cubic crystallite serves as the seed for crystallization from the amorphous phase. When an hcp seed is used, the maximum hcp-Ni fraction in the final crystal increases to 58.25% with 13 iterations. This study shows the promise of using BO to identify the process conditions that can maximize the rare phases. This method can also be generally applicable to process optimization to achieve target material properties. [ABSTRACT FROM AUTHOR]

In the present work, Zinc ferrite composites with Mango starch (MS) and carboxymethyl mango starch (CMMS) were synthesized for the removal of Ni (II) ions from aqueous solutions. Composites prepared were characterized by Fourier Transform Infrared (FTIR) Spectroscopy, X-Ray Diffraction (XRD) analysis, pH of point zero charge (pHzpc), Scanning Electron Microscopy (SEM), and BET. Batch adsorption technique was used to study effect of various parameters such as pH, adsorbent dose, contact time, concentration, and temperature for removal of Ni (II) ions from aqueous solutions. The optimum time, pH, adsorbent dose and temperature required for ZFN@ MS and ZFN@ CMMS in this study was 110 min., 7 & 8, 0.1 g and 308 K, respectively. Out of various adsorption isotherms, Freundlich isotherm model fitted best with adsorption data. Maximum adsorption capacity for removal of Ni (II) were found to be 65.3 and 208.3 mg/g, respectively by using Zinc ferrite@ MS and Zinc ferrite@ CMMS adsorbents. Lagergren Pseudo second order model best fitted with results which indicated that the process of adsorption was chemical in nature. The value of adsorption energy for ZFN@ MS was 50 kJ/mol and for ZFN@ CMMS, it was 31.62 kJ/mol. Thermodynamic study revealed that process was endothermic and non-spontaneous in nature. Regeneration studies were conducted for five cycles where Zinc ferrite@ MS showed 71% regeneration efficiency and Zinc ferrite@ CMMS showed 78% regeneration efficiency for nickel ion removal from aqueous solution. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Unsymmetric sulfides and selenides have great applications in the pharmaceutical field. Herein, we describe the reductive coupling reaction of xanthate esters with sulfur‐containing and selenium‐containing compounds (thio(seleno)sulfonates and disulfides(selenides)) under the nickel‐catalyzed condition. It provides a mild and effective method for the synthesis of unsymmetric sulfides and selenides which has the advantages of mild reaction conditions, high yields and a wide range of substrates. [ABSTRACT FROM AUTHOR]

Two coordination complexes [Ni(Hpydco)2(bpy)] (1) and [Ni(pydco)(phen)(H2O)2]·4.5H2O 0.5CH3OH (2) have been synthesized using a mixed-ligand system including pyridine-2,5-dicarboxylic acid N-oxide (H2pydco) as an O-donor ligand and 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) as a chelating N-donor ligand and NiCl2.6H2O as a source for Ni ions. The crystal structures of 1 and 2 form discrete complexes in which extensive π−π stacking interactions between aromatic rings of the N-donor ligands resulted in the formation of one dimensional (1D) chain-like structures. The chains are connected by hydrogen bonds to expand the structures into 2D-supramolecular networks. Hirshfeld surface analysis and Density Functional Theory (DFT) calculations were included to rationalize the relative strength of the π-stacking assemblies observed in both complexes. [ABSTRACT FROM AUTHOR]

Water purity plays a key role in medical applications such as clinical diagnosis, drug delivery, sterilization, and patient management. One of the most important medical treatments in which the quality of water is very important is hydrotherapy. Most of the patients have weakened immune systems due to existing infections, making them highly vulnerable to new infections from contaminated water in hydrotherapy pools. Therefore, the hydrotherapy water should be tested to ensure the safety of the patients' lives. In this research, a fiber optic bilayer sensor consisting of silver, copper, platinum, nickel, and gold as the metal layer, and scandium oxide as the second layer, has been numerically simulated to test water purity for hydrotherapy applications. The proposed configuration gives water purity detection with a maximum sensitivity of 4594.0°/RIU for Ni/Sc2O3 while the contacting length is considered as 10 mm, which is much higher than the conventional sensor. It is a topic of interest to researchers in related areas. Ag/Sc2O3 exhibits the highest figure of merit value compared to other materials. At the second part of the study, the effect of a silver-aluminum alloy has been investigated to enhance the quality factor of the winner structure (Ag/Sc2O3). The most efficient silver-aluminum combination ratio is found to be 0.1:0.9, which enhances the sensor quality factor from 40.50 to 60.45 (RIU−1) in aqueous media, while the refractive index of water changes from 1.33 to 1.34. [ABSTRACT FROM AUTHOR]

An electrochemical approach was used to synthesise nickel iron sulphide (NiFeS) materials in this work. The prepared NiFeS underwent a thorough investigation, which included analyses of its optical, electrical, structural, morphological, elemental, and functional group properties. Cubic crystal formations with prominent peaks were visible from the structural pattern. Nanoflakes and pebbles were visible, and their elements were determined through elemental dispersive X-ray diffractometer (EDX) spectrum. The film's crystallinity increased after incorporating carbon ions and its optical properties improved, with energy band gap values ranging from 1.50 eV to 1.15 eV as the peaks became more distinct. The materials produced could be utilised in the production of solar cells and optoelectronic devices. The electrical conductivity diminishes with increasing thickness. Carbon ion radiation increases carrier concentration, which increases electrical conductivity. NiFeS was irradiated using 500 keV carbon C++ ions beam irradiation NiFeS without irradiation has a bandgap of 1.50 eV, while the irradiated material had bandgaps between 1.35-1.15 eV. The film's crystallinity was enhanced by incorporating carbon ions Nanogels and nanoflakes were seen in the micrographs of the unirradiated materials. [ABSTRACT FROM AUTHOR]

Monolithic TS-1 can solve the problem of industrial separation caused by TS-1 powder, However, the influence of the support on the internal structure of TS-1 remains to be studied. The support capable of regulating the internal structure of TS-1 is required. In this article, using Polyacrylonitrile (PAN) as carbon and nitrogen source, nitrogen-doped carbon layer decorated nickel foam (NC@HNF) was synthesized by CSD (Chemical Solid Deposition) method for the first time, which can be stable in nitrogen atmosphere at 550 °C for 6 h. The monolithic TS-1 was successfully synthesized by loading TS-1 particles on NC@HNF, and the N atom doped in NC@HNF can effectively regulate the internal structure of TS-1. By optimizing the growth temperature and time of nitrogen-doped carbon layer, the support with both high carbon order degree and high nitrogen content was obtained, and the further obtained monolithic TS-1 had smaller particle size and higher content of Lewis acid, showing excellent catalytic performance in the propylene epoxidation reaction. The pyridine nitrogen in NC@HNF can promote the dehydration condensation of Si − OH and Ti − OH, effectively reducing the energy barrier of the dehydration condensation process and allowing more Ti − OH to enter the MFI topological framework of TS-1, which was confirmed by simulation. [ABSTRACT FROM AUTHOR]

The hydrogenation reaction of guaiacol in the gas phase at 300 °C and atmospheric pressure of hydrogen was investigated over Ni-based catalysts supported on niobium oxide (Nb2O5) and exfoliated potassium hexaniobate (Nb-exf). The catalysts were prepared by two different methods: photodeposition (pd) and incipient wetness impregnation (im) and were characterized by N2 adsorption–desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption of ammonia (NH3-TPD) analyses. XRD analysis showed that all catalysts exhibited approximately the same crystallite size of the metallic nickel (15 nm). Regarding the catalytic tests, guaiacol was mainly converted to catechol (59.5–80.6%) and phenol (4.4–14.2%) regardless of the catalyst. Small amounts of benzene were only observed over Ni(im)/Nb2O5. The catalytic experiments showed that the main reaction pathway is the conversion of guaiacol through demethylation reaction producing catechol followed by phenol formation via dehydroxylation reaction. Ni(im)/Nb2O5 was tested for catalytic upgrading of pyrolysis vapor of different biomasses (lignin, microalgae, and malt residue), and it was able to reduce the yield of oxygenated products. The catalytic upgrading of pyrolysis vapor of microalgae using a catalyst-to-biomass weight ratio (C:B) of 3:1 showed the highest selectivity of hydrocarbons (57.44%). The catalyst concentration and the biomass used in the test showed a high influence on the product distribution. [ABSTRACT FROM AUTHOR]

Electronic waste (e-waste) illegally disposal in Thailand is becoming more widespread. A sustainable metal recovery technology is needed. A phytotechnology called "phytomining" of metals such as nickel (Ni) is a promising technology providing a sustainable solution to the growing e-waste problems. This study investigated the ability of Acacia species in association with e-waste site isolated, plant growth-promoting rhizobacteria (PGPR), Bacillus amyloliquefaciens. Acacia mangium accumulated higher Ni in their tissues when Ni concentrations in soil were lower than 200 mg kg−1. The inoculation of PGPR B. amyloliquefaciens enhanced Ni uptake and accumulation in the leaves, stem, and root. The results showed that the highest Ni concentration was found in the root ash (825.50 mg kg−1) when inoculated plants were grown in soil containing 600 mg kg−1 Ni. Hence, the Ni recovery process and mass balance were performed on root ashes. The highest Ni recovery was 91.3% from the acid (H2SO4) leachate of the ash of inoculated plant treated with 600 mg kg−1 Ni. This demonstrates the feasibility of PGPR-assisted phytomining from Ni-contaminated soil. Phytomining of Ni from any e-waste contaminated sites using Acacia mangium in combination with B. amyloliquefaciens can promote plant growth and improve the uptake of Ni. Phytomining from electronic waste is an appealing technology that can provide a long-term waste management strategy while valuable trace metals can be recovered. In this study, we evaluated the nickel phytomining ability of Acacia mangium in association with PGPR Bacillus amyloliquefaciens. The results from this study showed that Ni recovery from phytomass using A. mangium with B. amyloliquefaciens can be further improved leading to a sustainable waste management strategy. [ABSTRACT FROM AUTHOR]

The solvent extraction of cobalt (II) and nickel (II) from a sulfate medium using di (2-ethylhexyl) phosphoric acid (D2EHPA) dissolved in chloroform was studied in the absence and presence of the synergic agent 1-octanol according to the following parameters: pH, concentrations of the extractant and 1-octanol. The extraction reaction of cobalt (II) and nickel (II) with the synergistic mixture was determined using slope analysis in the presence of 1-octanol. The extraction curves show several species of complexes that depend on the concentration of 1-octanol. For very weak concentrations, the extracted complexes are ML2(org). For high concentrations, the extracted complexes are ML2(org)(1-octanol)(org) and ML2(org) (1-octanol)3(org) (M = Co, Ni). A mechanism and structure for the metal-extractant complex formed during the synergistic extraction were suggested. [ABSTRACT FROM AUTHOR]

We show that powder pressed specimens of nickel can be sintered to 99.96% density by injecting electrical current, without the use of a furnace. Full sintering could be accomplished in 10 to 52 s by changing the current rate from 5 to 1 A/s. In all instances, the samples sintered abruptly at a current density of ∼20 A mm−2. The grain size of the sintered samples was somewhat larger than the nickel powder particle size (∼60 μm vs. 40 μm). Tensile testing yielded a yield strength of 98 MPa, ultimate tensile stress of 323 MPa, and ductility of ∼17%. Four in‐operando measurements are reported: (i) sintering, (ii) the change in resistance with current density, (iii) the temperature, and (iv) electroluminescence. The change in resistance during flash sintering exhibited a high peak followed by a steep decline in resistance; the transient is attributed to the breakdown of particle–particle interface resistance. The same cycle repeated with the flash‐sintered, dense sample, did not show the spike, and gave reproducible results. The resistance data for these latter cycles, when viewed as a function of temperature exhibited sigmoidal behavior: initially lower, and then higher than the literature values. This unusual behavior reflects the influence of defects generated during flash. We have also measured the endothermic enthalpy, expressed by the difference between the in situ input electrical energy and the radiation, convection, and specific heat losses. Dividing by the formation energy of Frenkel pairs yields the concentration of defects, estimated to be 0.3–0.4 mol %. These concentrations are far above thermal equilibrium; it is concluded that flash of metals is a far from equilibrium phenomenon. [ABSTRACT FROM AUTHOR]

Decarboxylative cross‐coupling is a significant method in organic synthesis where inexpensive and stable carboxylic acids are used as substrates for the construction of C−C and C‐heteroatom bonds. First‐row 3d transition metals including nickel have recently been recognized as advantageous alternative to noble metals in transition metal catalysed decarboxylative couplings. In this review, Ni‐based catalysts for C−C (Csp3/Csp2/Csp) and C‐heteroatom (C−N, C−P, C−S, C−Si) cross‐couplings are summarized and most of the strategies find applications in the synthesis and modification of biologically important molecules. Importantly, Ni‐dual catalysis under photocatalytic and electrochemical conditions form the state of the art research in the field. This is the first review reported exclusively on Ni‐catalysed decarboxylative cross‐coupling and cover reports from 2009 to present. [ABSTRACT FROM AUTHOR]

Olefin hydrogenation is one of the most important transformations in organic synthesis. Electrochemical transition metal‐catalyzed hydrogenation is an attractive approach to replace the dangerous hydrogen gas with electrons and protons. However, this reaction poses major challenges due to rapid hydrogen evolution reaction (HER) of metal‐hydride species that outcompetes alkene hydrogenation step, and facile deposition of the metal catalyst at the electrode that stalls reaction. Here we report an economical and efficient strategy to achieve high selectivity for hydrogenation reactivity over the well‐established HER. Using an inexpensive and bench‐stable nickel salt as the catalyst, this mild reaction features outstanding substrate generality and functional group compatibility, and distinct chemoselectivity. In addition, hydrodebromination of alkyl and aryl bromides could be realized using the same reaction system with a different ligand, and high chemoselectivity between hydrogenation and hydrodebromination could be achieved through ligand selection. The practicability of our method has been demonstrated by the success of large‐scale synthesis using catalytic amount of electrolyte and a minimal amount of solvent. Cyclic voltammetry and kinetic studies were performed, which support a NiII/0 catalytic cycle and the pre‐coordination of the substrate to the nickel center. [ABSTRACT FROM AUTHOR]

Upgrading CO2 to value‐added chiral molecules via catalytic asymmetric C−C bond formation is a highly important yet challenging task. Although great progress on the formation of centrally chiral carboxylic acids has been achieved, catalytic construction of axially chiral carboxylic acids with CO2 has never been reported to date. Herein, we report the first catalytic asymmetric synthesis of axially chiral carboxylic acids with CO2, which is enabled by nickel‐catalyzed dynamic kinetic asymmetric reductive carboxylation of racemic aza‐biaryl triflates. A variety of important axially chiral carboxylic acids, which are valuable but difficult to obtain via catalysis, are generated in an enantioconvergent version. This new methodology features good functional group tolerance, easy to scale‐up, facile transformation and avoids cumbersome steps, handling organometallic reagents and using stoichiometric chiral materials. Mechanistic investigations indicate a dynamic kinetic asymmetric transformation process induced by chiral nickel catalysis. [ABSTRACT FROM AUTHOR]

Olefin hydrogenation is one of the most important transformations in organic synthesis. Electrochemical transition metal‐catalyzed hydrogenation is an attractive approach to replace the dangerous hydrogen gas with electrons and protons. However, this reaction poses major challenges due to rapid hydrogen evolution reaction (HER) of metal‐hydride species that outcompetes alkene hydrogenation step, and facile deposition of the metal catalyst at the electrode that stalls reaction. Here we report an economical and efficient strategy to achieve high selectivity for hydrogenation reactivity over the well‐established HER. Using an inexpensive and bench‐stable nickel salt as the catalyst, this mild reaction features outstanding substrate generality and functional group compatibility, and distinct chemoselectivity. In addition, hydrodebromination of alkyl and aryl bromides could be realized using the same reaction system with a different ligand, and high chemoselectivity between hydrogenation and hydrodebromination could be achieved through ligand selection. The practicability of our method has been demonstrated by the success of large‐scale synthesis using catalytic amount of electrolyte and a minimal amount of solvent. Cyclic voltammetry and kinetic studies were performed, which support a NiII/0 catalytic cycle and the pre‐coordination of the substrate to the nickel center. [ABSTRACT FROM AUTHOR]

Upgrading CO2 to value‐added chiral molecules via catalytic asymmetric C−C bond formation is a highly important yet challenging task. Although great progress on the formation of centrally chiral carboxylic acids has been achieved, catalytic construction of axially chiral carboxylic acids with CO2 has never been reported to date. Herein, we report the first catalytic asymmetric synthesis of axially chiral carboxylic acids with CO2, which is enabled by nickel‐catalyzed dynamic kinetic asymmetric reductive carboxylation of racemic aza‐biaryl triflates. A variety of important axially chiral carboxylic acids, which are valuable but difficult to obtain via catalysis, are generated in an enantioconvergent version. This new methodology features good functional group tolerance, easy to scale‐up, facile transformation and avoids cumbersome steps, handling organometallic reagents and using stoichiometric chiral materials. Mechanistic investigations indicate a dynamic kinetic asymmetric transformation process induced by chiral nickel catalysis. [ABSTRACT FROM AUTHOR]

Surface chemical etching for the in situ growth of metal–organic materials and electrochemical reconstruction are expected to efficiently improve the catalytic performance of oxygen evolution reactions (OERs). In this work, 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM]HSO4) was used to chemically etch the surface structure of nickel foams (NFs) and form metal–organic thin films in situ at the surface of the NF ([BMIM]–SO4–Ni@NF). Anion HSO4− in [BMIM]HSO4 chemically etched the NF surface to provide bivalent nickels (Ni2+). Ni2+ and [BMIM]HSO4 formed a [BMIM]–SO4–Ni coating in situ on the surface of the modified NF. During the OER process, nitrogen and sulfur leached out from the surface of [BMIM]–SO4–Ni@NF, along with the reconstruction of [BMIM]–SO4–Ni@NF to C–NiOOH@NF. C–NiOOH@NF possessed a hierarchical and defective nanoflower structure and enlarged the electrochemical active surface area and surface-active sites for OER activity. The effect of [BMIM]HSO4 on the performance of oxygen evolution reactions (OERs) was investigated. The results indicated that [BMIM]HSO4 modification promoted the formation of γ-NiOOH and significantly improved the OER performance of NFs. The OER performance was obtained at a [BMIM]HSO4 mass concentration ([BMIM]HSO4%) of 2.4%. However, high [BMIM]HSO4% results in the damage of the NF frame structure and a high content of carbon doping, leading to a reduction in OER activity. [ABSTRACT FROM AUTHOR]

Biocarbon catalysts for reverse water‐gas shift reaction (RWGS) were produced from pyrolyzed fern and willow impregnated with iron and nickel nitrates. This reaction can partake during Fischer‐Tropsch synthesis (FTS) by consuming CO2 and lowering both the H2/CO ratio and the efficiency in the production of fuels. RWGS has attracted much attention to widespread utilization of CO2 through the production of syngas. The catalysts were therefore tested in a fixed‐bed reactor at 400 °C as it is the maximal temperature for FTS and high RWGS. They showed high selectivity towards CO (>84 %) and fair conversion (<17 %) compared to rust (81 %, 30 %, respectively) and Fe‐impregnated alumina (100 %, 8 %). No loss in selectivity and conversion was observed for a longer residence time (288 h). Biomass inherent metals could provide reactive gas adsorption sites that improve conversion by dispersing electrons which reduces adsorption and dissociation energy barriers. K, Mg and Ca in fern biocarbon catalysts may be related to the higher CO2 uptake compared to willow catalysts. Electron deficient sites produced by reduction of biocarbon oxygen functional groups may facilitate CO2 uptake and activation. Ni‐impregnated fern‐based biocarbon showed the highest activity, due to the synergetic effect of the inherent metals, O vacancies and strong metal‐carbon interactions. [ABSTRACT FROM AUTHOR]

Because internal alkenes are more challenging synthetic targets than terminal alkenes, metal‐catalyzed olefin mono‐transposition (i.e. positional isomerization) approaches have emerged to afford valuable E‐ or Z‐ internal alkenes from their complementary terminal alkene feedstocks. However, the applicability of these methods has been hampered by lack of generality, commercial availability of precatalysts, and scalability. Here, we report a nickel‐catalyzed platform for the stereodivergent E/Z‐selective synthesis of internal alkenes at room temperature. Commercial reagents enable this one‐carbon transposition of terminal alkenes to valuable E‐ or Z‐internal alkenes via a Ni−H‐mediated insertion/elimination mechanism. Though the mechanistic regime is the same in both systems, the underlying pathways that lead to each of the active catalysts are distinct, with the Z‐selective catalyst forming from comproportionation of an oxidative addition complex followed by oxidative addition with substrate and the E‐selective catalyst forming from protonation of the metal by the trialkylphosphonium salt additive. In each case, ligand sterics and denticity control stereochemistry and prevent over‐isomerization. [ABSTRACT FROM AUTHOR]

Because internal alkenes are more challenging synthetic targets than terminal alkenes, metal‐catalyzed olefin mono‐transposition (i.e. positional isomerization) approaches have emerged to afford valuable E‐ or Z‐ internal alkenes from their complementary terminal alkene feedstocks. However, the applicability of these methods has been hampered by lack of generality, commercial availability of precatalysts, and scalability. Here, we report a nickel‐catalyzed platform for the stereodivergent E/Z‐selective synthesis of internal alkenes at room temperature. Commercial reagents enable this one‐carbon transposition of terminal alkenes to valuable E‐ or Z‐internal alkenes via a Ni−H‐mediated insertion/elimination mechanism. Though the mechanistic regime is the same in both systems, the underlying pathways that lead to each of the active catalysts are distinct, with the Z‐selective catalyst forming from comproportionation of an oxidative addition complex followed by oxidative addition with substrate and the E‐selective catalyst forming from protonation of the metal by the trialkylphosphonium salt additive. In each case, ligand sterics and denticity control stereochemistry and prevent over‐isomerization. [ABSTRACT FROM AUTHOR]

The production of hydrogen-rich gas used in fuel cell-powered cars from steam reforming and sorption-enhanced steam reforming of ethanol was studied over nickel-impregnated mesoporous carbon catalyst in conventional and microwave heated reactor systems. Two important process intensification methods, sorption-enhanced reforming and microwave heating, were investigated to obtain a sustainable and energy-efficient system. Higher hydrogen yield was observed in the microwave heated system compared to the conventional heated system. With an increase in the reaction temperature, the hydrogen yield and hence the hydrogen concentration were increased in both systems. Sorption-enhanced steam reforming resulted in very high hydrogen purity, higher than 97 %, containing no carbon monoxide and carbon dioxide before the breakthrough point in the microwave system at 500 °C. The outperformance of the microwave system compared to the conventional system was proved in terms of the hydrogen yield and purity. • Nickel impregnated mesoporous carbon catalyst has a high microwave absorption capacity in the microwave system. • Higher hydrogen yield and purity were achieved in the microwave system. • Sorption-enhanced results revealed very high H 2 purity in the MW reactor at 500 °C during the first 25 min of the reaction. • The enhancement in hydrogen yield and purity in the MW system are evidence of its superiority to the conventional system. [ABSTRACT FROM AUTHOR]

Bioaccessibility of metals from substances and alloys is increasingly used as part of the assessment to predict potential toxicity. However, data are sparse on the metal bioaccessibility from nanoparticle (NP) size metal substances. This study examines nickel ion release from metallic nickel and nickel oxide micron particles (MPs) and NPs in simulated biological fluids at various timepoints including those relevant for specific routes of exposure. The results suggest that MPs of both metallic nickel and nickel oxide generally released more nickel ions in acidic simulated biological fluids (gastric and lysosomal) than NPs of the same substance, with the largest differences being for nickel oxide. In more neutral pH fluids (interstitial and perspiration), nickel metal NPs released more nickel ions than MPs, with nickel oxide results showing a higher release for MPs in interstitial fluid yet a lower release in perspiration fluid. Various experimental factors related to the particle, fluid, and extraction duration were identified that can have an impact on the particle dissolution and release of nickel ions. Overall, the results suggest that based on nickel release alone, nickel NPs are not inherently more hazardous than nickel MPs. Moreover, analyses should be performed on a case-by-case basis with consideration of various experimental factors and correlation with in vivo data. [ABSTRACT FROM AUTHOR]

Hydrogen, one of the most promising forms of new energy sources, due to its high energy density, low emissions, and potential to decarbonize various sectors, has attracted significant research attention. It is known that electrocatalytic hydrogen production is one of the most widely investigated research directions due to its high efficiency in the conversion of electricity to H2 gas. However, given the limited reserves and high cost of precious metals, the search for non-precious metal-based catalysts has been widely explored, for example, transition metal phosphides, oxides, and sulfides. Despite this interest, a detailed survey unveils that the surface and internal structures of the alternative catalysts, including their surface reconstruction, composition, and electronic structure, are poorly studied. As a result, a disconnection in the structure–property relationship severely hinders the rational design of efficient and reliable non-precious metal-based catalysts. In this review, by focusing on Ni5P4, a bifunctional catalyst for water splitting, we systematically summarize the material motifs pertaining to the different synthetic methods, surface characteristics, and hydrolysis properties. It is believed that a cascaded correlation may provide insights toward understanding the fundamental catalytic mechanism and design of robust alternative catalysts for hydrogen production. [ABSTRACT FROM AUTHOR]

The effects of adding nickel on the phase transition temperature, microstructure, and mechanical properties of medium-carbon spring steel have been investigated. The results show that adding nickel reduces the martensite start (Ms) temperature, improves hardenability, and refines the sub-microstructure of the martensite, thereby improving yield stress. The yield strength of martensitic steel increases by approximately 100 MPa due to a synergistic combination of grain refinement strengthening and dislocation strengthening, with an increase in the nickel content from 0 wt.% to 1 wt.%. The cryogenic impact toughness of martensitic steel also improved with a higher nickel content due to packet and block refinement and an increase in the proportion of high-angle grain boundaries (HAGBs). [ABSTRACT FROM AUTHOR]

Mining activities have increased the potential risks of metal pollution to the groundwater resources in arid areas across the globe. Therefore, this study aimed to examine the health risk associated with nickel (Ni) in the groundwater sources of a mining-impacted area, South Khorasan, Eastern Iran. A total of 110 stations were included in the study, comprising 62 wells, 40 qanats, and 8 springs in summer, 2020. Initially, the collected samples were tested for temperature, pH, and electrical conductivity (EC). Subsequently, the samples were filtered and treated with nitric acid (HNO3) to measure the concentration of Ni using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Hazard quotient (HQ) and non-carcinogenic risk assessments were employed to evaluate the potential risks of Ni to the inhabitants. The findings revealed that the concentration of Ni ranged from 0.02 to 132.39 μg l−1, and only two stations exhibited Ni concentrations above the WHO standards (20 μg l−1). The results demonstrated that 98.21% of the sampled locations had HQ values below one, indicating negligible risk, while 1.78% of the stations exhibited HQ values of one or higher, representing a high non-carcinogenic risk for water consumers. Overall, the concentration of nickel in the groundwater of South Khorasan exceeded the World Health Organization (WHO) limit solely in the Halvan station, posing a non-carcinogenic risk for the residents in that area, and therefore, additional efforts should be made to provide healthier groundwater to consumers in this region. [ABSTRACT FROM AUTHOR]

Nickel (Ni) is a heavy metal that adversely affects the growth of different crops by inducing oxidative stress and nutrient imbalance. The role of rhizobacteria (RB) is vital to resolve this issue. They can promote root growth and facilitate the uptake of water and nutrients, resulting in better crop growth. On the other hand, γ-aminobutyric acid (GABA) can maintain the osmotic balance and scavenge the reactive oxygen species under stress conditions. However, the combined effect of GABA and RB has not been thoroughly explored to alleviate Ni toxicity, especially in fenugreek plants. Therefore, in the current pot study, four treatments, i.e., control, A. fabrum (RB), 0.40 mM GABA, and 0.40 mM GABA + RB, were applied under 0Ni and 80 mg Ni/kg soil (80Ni) stress. Results showed that RB + 0.40 mM GABA caused significant improvements in shoot length (~ 13%), shoot fresh weight (~ 47%), shoot dry weight (~ 47%), root length (~ 13%), root fresh weight (~ 60%), and root dry weight (~ 15%) over control under 80 Ni toxicity. A significant enhancement in total chlorophyll (~ 14%), photosynthetic rate (~ 17%), stomatal CO2 concentration (~ 19%), leaves and roots N (~ 10 and ~ 37%), P (~ 18 and ~ 7%) and K (~ 11 and ~ 30%) concentrations, while a decrease in Ni (~ 83 and ~ 49%) concentration also confirmed the effectiveness of RB + 0.40 mM GABA than control under 80Ni. In conclusion, fabrum + 0.40 mM GABA can potentially alleviate the Ni toxicity in fenugreek plants. The implications of these findings extend to agricultural practices, environmental remediation efforts, nutritional security, and ecological impact. Further research is recommended to elucidate the underlying mechanisms, assess long-term effects, and determine the practical feasibility of using A. fabrum + 0.40GABA to improve growth in different crops under Ni toxicity. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Unsymmetrical diarylamines are crucial components in many pharmaceuticals and functional materials. In this study, we introduce an efficient Chan‐Lam cross‐coupling method that utilizes phenylboronic acids and aryl azides as coupling agents in a redox‐neutral environment, enabled by a synergistic nickel/photoredox catalytic system. This approach leverages a proton‐coupled electron transfer mechanism to bypass the typical nitrene pathway associated with aryl azides, which is prone to intramolecular rearrangement, C—H amination, and reductive hydrogenation. Notably, our method exhibits broad compatibility with a variety of functional groups, including those derived from pharmaceuticals, demonstrating its versatile potential in organic synthesis and drug modification. [ABSTRACT FROM AUTHOR]

This article provides an overview of the progress and challenges in the field of nickel-catalyzed C–H activation. It emphasizes the importance of this process in converting readily available chemicals into valuable small molecules. The authors compare nickel and palladium catalysts, discussing their reactivity and mechanistic features. The article also highlights the need for further research to understand the mechanisms involved and to develop more efficient transformations. It explores the use of different bases and directing groups, as well as the thermochemical properties and selectivity of the reactions. The text includes examples of primary C-H activation reactions and discusses recent developments in this area. It also addresses the limitations and future directions for research, such as the preference for methyl groups and the exploration of more remote C-H groups. [Extracted from the article]

This article explores the nickel-catalyzed transesterification of methyl esters, which is an important process in synthetic chemistry. The authors discuss the challenges of activating esters for cross-coupling reactions and the development of a reversible transformation using a nickel catalyst and SIPr. They also investigate the optimization of the reaction and the identification of effective ligands for different types of esters. The goal is to develop a transesterification method that is different from traditional acid- and base-mediated pathways. The article presents the development of a catalytic transesterification reaction using methyl esters and aliphatic alcohols, with optimized conditions and successful formation of diverse esters. The reaction is advantageous because it only produces methanol as waste and does not require the use of acids or bases. Mechanistic studies suggest that the cleavage of the C(acyl)-O bond is reversible, and ongoing research is being conducted on the use of methyl esters as cross-coupling electrophiles. [Extracted from the article]

The present study proposes La and Sr‐containing La1−xSrxNi0.8Zr0.2O3 (x=0.1, 0.2, 0.4, 0.6, 0.8) perovskites as potential catalysts for bi‐reforming of methane (BRM) with CO2 and steam to produce hydrogen rich syngas. The catalysts were prepared by sol‐gel method and characterized using various techniques such as XRD, H2‐TPR, BET, CO2‐TPD and CHNS analysis. The characterization studies revealed that metal‐support interaction increased with the increase in the composition of Sr and the reduction behavior of Ni found to vary with the addition of Sr. The total energy calculations reveal that the addition of Sr to the LNZ system shirnks the volume due to low atomic and high ionic radii of Sr over La, which increases the total energy of system driving towards instability with increasing doping concentration of Sr. CO2‐TPD results suggest that a small amount of Sr can change the basicity of the support. The BRM activity results revealed that La0.8Sr0.2Ni0.8Zr0.2O3 perovskite is the most promising and active catalyst. The proposed catalysts are found to be advantageous w.r.t less carbon deposition due to the increased dispersion, small crystalline size, and required basicity of the support. The disclosed catalyst has shown excellent stability for a studied period of 100 h. [ABSTRACT FROM AUTHOR]

A series of nickel hydroxyapatite catalysts were synthesized by the co‐precipitation method followed by calcination and reduction. These catalysts were employed for the aqueous phase hydrogenation of glucose to sorbitol. The Ni‐HAP catalyst with comparatively high surface area and acid‐base strength gave high sorbitol selectivity in 1 h. Ni‐HAP‐4 catalyst with moderate Ni (3.5 wt. %) content having smaller and highly dispersed nickel particles gives an excellent yield of sorbitol, 97 % in 1 h. The Ni‐HAP‐4 catalyst works well with other polar protic solvents. Different characterization techniques like XRD, TEM, SEM‐EDS, BET, NH3‐TPD, and CO2‐TPD were employed to analyze the Ni‐HAP‐4 catalyst. [ABSTRACT FROM AUTHOR]

A 3D hierarchical nickel--iron hexacyanoferrate electrocatalyst was successfully grown on nickel foam using an energy-efficient in situ self-assembly method. The as-prepared NiFeHCF@NF electrode has good morphology and intimate contact with the NF compared to electrodes from the co-precipitation method. The well-designed NiFeHCF@NF nanostructure delivers prominent performances that require overpotentials as low as 210 and 125 mV@10 mA cm-2 for the OER and HER in 1 M KOH, respectively. Tafel slope and electrochemical impedance studies further revealed favourable kinetics during electrolysis. Hence, an NiFeHCF@NF--NiFeHCF@NF water electrolyser only required 1.56 V@10 mA cm-2 with an ~2.5% potential loss. Furthermore, the synergistic effect of iron and nickel with ferrocyanide improved the structural stability and promoted the generation of active phases during the OER/HER, resulting in outstanding durability for 150 h. Moreover, the novel all-in-one strategy can be used to explore other bifunctional and cost-efficient electrocatalysts for various applications. The solar-based water electrolysis and environmental assessment confirmed the practical use of NiFeHCF@NF for eco-friendly industrial hydrogen production. [ABSTRACT FROM AUTHOR]

2,5-Furandicarboxylic acid (FDCA) is an important bio-derived monomer to produce poly(ethylene 2,5- furandicarboxylate) (PEF), known for its superior gas barrier properties in comparison with the widely used poly(ethylene terephthalate) (PET). Among the various synthesis routes to FDCA, electrocatalytic oxidation of furan precursors is an attractive choice due to its great energy efficiency with hydrogen as the coproduct. With the aim of efficiently producing FDCA and H2, we employed an electrodeposition and subsequent oxidation method to synthesize nickel--copper alloy catalysts for the electrolysis of 2,5-bis (hydroxymethyl)furan (BHMF). The optimized Ni7Cu3 catalyst exhibited a remarkable FDCA yield of 99.8% at nearly complete conversion of BHMF. In situ Raman spectroscopy revealed that Ni3+ species served as the active sites during the BHMF oxidation. Surface copper oxide facilitated the maintenance of the high valence state of Ni3+ during the reaction. The superior electrical conductivity of Cu compared to Ni boosted the transport of electrons from reactant molecules through the catalytic layer and collector to the outer circuit. The addition of nickel not only enhanced the catalytic activity of copper foam but also contributed to slowing down of the leaching of copper during electrolysis. This work provides novel insights into the mechanistic elucidation of alloy catalysts for biomass electrooxidation. [ABSTRACT FROM AUTHOR]

Ein einkerniges, T‐förmiges Palladium(I)‐d9‐ Metalloradikal (3), stabilisiert durch einen sterisch anspruchsvollen PNP‐Liganden mit Carbazolgerüst, wurde durch die Reduktion des Chloridokomplexes oder thermische Pd−C‐Bindungshomolyse des entsprechenden Neopentylkomplexes erhalten. Unter CO‐Druck bildete sich der Pd(I)‐Carbonylkomplex, der durch Röntgenbeugung strukturell charakterisiert wurde. Die Delokalisierung des ungepaarten Elektrons zum Carbonylkohlenstoff hin wurde durch EPR‐Spektroskopie nachgewiesen und durch DFT‐ und ab initio Methoden theoretisch modelliert. Das teilweise reduzierte und radikalisierte CO reagierte langsam mit Di(tert‐butyl)disulfid unter homolytischer S−S‐Spaltung und C−S‐Bindungsbildung zu dem entsprechenden Metallothioester. [ABSTRACT FROM AUTHOR]

Although cobalt oxides show great promise as supercapacitor electrode materials, their slow kinetics and low conductivity make them unsuitable for widespread application. We developed Ni and Cu-doped Co3O4 nanoparticles (NPs) via a simple chemical co-precipitation method without the aid of a surfactant. The samples were analyzed for their composition, function group, band gap, structure/morphology, thermal property, surface area and electrochemical property using X-ray diffraction (XRD), ICP-OES, Fourier transform infrared (FTIR) spectroscopy, Ultraviolet-visible (UV-Vis), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and/or Differential thermal analysis (DTA), Brunauer-Emmett-Teller (BET), and Impedance Spectroscopy (EIS), Cyclic voltammetry (CV), respectively. Notably, for the prepared sample, the addition of Cu to Co3O4 NPs results in a 11.5-fold increase in specific surface area (573.78 m2 g-1) and a decrease in charge transfer resistance. As a result, the Ni doped Co3O4 electrode exhibits a high specific capacitance of 749 Fg-1, 1.75 times greater than the pristine Co3O4 electrode's 426 F g-1. The electrode's enhanced surface area and electronic conductivity are credited with the significant improvement in electrochemical performance. The produced Ni doped Co3O4 electrode has the potential to be employed in supercapacitor systems, as the obtained findings amply demonstrated. [ABSTRACT FROM AUTHOR]

The influence of the transition alloying element nickel and the alkaline earth element strontium on the microstructure and tensile properties of squeeze cast Al−Si‐Cu alloy under as‐cast condition at elevated temperature of 100 °C, 200 °C and 300 °C is investigated in comparison with the conventional Al−Si‐Cu alloy (A380). Aluminum alloy A380 is alloyed and modified with 2 wt% additional nickel (Ni) and 0.02 wt% strontium (Sr). Squeeze casting is employed to cast the modified A380 under an applied pressure of 90 MPa. The results of tensile testing at the selected elevated temperatures indicate that the Ni and Sr containing A380 alloy exhibits a significantly improvement on tensile properties, specifically ultimate tensile strength and yield strength with 10 %‐30 % increases. The as‐cast microstructures of both the conventional and Ni and Sr‐containing alloys are observed by an optical microscope and further analyzed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The presence of Ni‐containing intermetallic phases with Ni addition, and the modified eutectic Si phase with refined morphologies due to the Sr addition should be responsible for the considerable enhancement on the as‐cast strengths of the squeeze cast Ni‐ and Sr‐containing alloy over those of the conventional A380 alloy. [ABSTRACT FROM AUTHOR]

Brass alloys contain the dangerous element lead. Material engineering is carried out to reduce the lead element in brass alloys and add nickel elements as a substitute for lead elements by the casting process. The phenomenon analyzed in this study explains comparing the accuracy level of OES and EDX test results on nickel dissolution in brass casting, especially in adding nickel elements. So that researchers can compare the decrease in the percentage of nickel element composition in the OES test results. At the same time, there is an increase in nickel element composition in the EDX test results. The brass dissolution process uses an electric furnace with an initial temperature of 526 °C. Elemental nickel was introduced into brass solution and dissolved elemental nickel at 978 °C for 120 min for a variation of 1 %, 2 %, 3 %, and for 180 min for a variation of 4 %. The composition of alloying elements is tested using OES and EDX. The dissolution process of brass with the addition of nickel elements tested with OES decreased from 1 % nickel elements to 0.650 %, 2 % to 1.630 %, 3 % to 2.046 %, and 4 % to 2.810 %. Meanwhile, from the EDX test results, there was an increase in the composition of nickel elements from nickel 1 % to 1.41 %, 2 % to 2.57 %, 3 % to 3.41 %, and 4 % to 4.49 %. Brass alloys with nickel elements added decreased due to slag produced during the dissolution process of nickel elements in molten brass from the test results using OES. EDX testing results in an increase in the percentage of nickel elemental composition. The results of the OES test validation of the mechanical properties of adding nickel elements to brass alloys can be considered because the material's strength is still under the reference UNS C89550. This research contribution resulted in an effective and efficient test method with OES to analyze the elemental composition in brass alloys to which nickel elements have been added. [ABSTRACT FROM AUTHOR]

Background Industrial facilities are not located uniformly across communities in the United States, but how the burden of exposure to carcinogenic air emissions may vary across population characteristics is unclear. We evaluated differences in carcinogenic industrial pollution among major sociodemographic groups in the United States and Puerto Rico. Methods We evaluated cross-sectional associations of population characteristics including race and ethnicity, educational attainment, and poverty at the census tract level with point-source industrial emissions of 21 known human carcinogens using regulatory data from the US Environmental Protection Agency. Odds ratios and 95% confidence intervals comparing the highest emissions (tertile or quintile) to the referent group (zero emissions [ie, nonexposed]) for all sociodemographic characteristics were estimated using multinomial, population density–adjusted logistic regression models. Results In 2018, approximately 7.4 million people lived in census tracts with nearly 12 million pounds of carcinogenic air releases. The odds of tracts having the greatest burden of benzene, 1,3-butadiene, ethylene oxide, formaldehyde, trichloroethylene, and nickel emissions compared with nonexposed were 10%-20% higher for African American populations, whereas White populations were up to 18% less likely to live in tracts with the highest emissions. Among Hispanic and Latino populations, odds were 16%-21% higher for benzene, 1,3-butadiene, and ethylene oxide. Populations experiencing poverty or with less than high school education were associated with up to 51% higher burden, irrespective of race and ethnicity. Conclusions Carcinogenic industrial emissions disproportionately impact African American and Hispanic and Latino populations and people with limited education or experiencing poverty thus representing a source of pollution that may contribute to observed cancer disparities. [ABSTRACT FROM AUTHOR]

Ni nanowire array electrodes with an extremely large surface area were made through an electrochemical reduction process utilizing an anodized alumina template with a pore length of 320 µm, pore diameter of 100 nm, and pore aspect ratio of 3200. The electrodeposited Ni nanowire arrays were preferentially oriented in the (111) plane regardless of the deposition potential and exhibited uniaxial magnetic anisotropy with easy magnetization in the axial direction. With respect to the magnetic properties, the squareness and coercivity of the electrodeposited Ni nanowire arrays improved up to 0.8 and 550 Oe, respectively. It was also confirmed that the magnetization reversal was suppressed by increasing the aspect ratio and the hard magnetic performance was improved. The electrocatalytic performance for hydrogen evolution on the electrodeposited Ni nanowire arrays was also investigated and the hydrogen overvoltage was reduced down to ~0.1 V, which was almost 0.2 V lower than that on the electrodeposited Ni films. Additionally, the current density for hydrogen evolution at −1.0 V and −1.5 V vs. Ag/AgCl increased up to approximately −580 A/m2 and −891 A/m2, respectively, due to the extremely large surface area of the electrodeposited Ni nanowire arrays. [ABSTRACT FROM AUTHOR]

For practicable elastomeric polyethylene, achieving high catalyst thermal stability and activity, along with precise control of polymer properties such as branching density, molecular weights, and distribution, is crucial but challenging. In this study, two sets of symmetrical α-diimine nickel complexes, each comprising four nickel bromide or chloride complexes, were synthesized and investigated their performance for ethylene polymerization under various reaction conditions. Upon activation with either Et2AlCl or MMAO cocatalysts, these complexes displayed not only high activity but also generated high molecular weight polyethylenes with controlled polydispersity and a substantial number of branches. The catalyst with the least steric hindrance displayed the remarkable high activity (up to 1.2×107 g·mol−1·h−1). Notably, nickel bromides demonstrated higher activity compared to their chloride counterparts. The investigation into the effect of reaction temperature on catalytic performance revealed that NiBrMe-MMAO system displayed high thermal stability (activity up to 2.51×106 g·mol−1·h−1 at 100 °C) and consistently yielded high polymer molecular weights with narrow polydispersity over a broad temperature range of 30–100 °C. Of significant note, mechanical analysis of the resulting polyethylene demonstrated excellent ultimate tensile strength and high strain at break. Particularly, the polyethylene sample prepared at 100 °C exhibited ultimate tensile strength up to 10 MPa with 1863% maximum strain at break and a strain recovery of up to 54.9% after ten cycles at a fixed strain of 300%, indicating excellent material properties of prepared thermoplastic polyethylene elastomers (TPE). [ABSTRACT FROM AUTHOR]

Recovery of nickel and cobalt from laterite ores is important to meet the demand for these metals. In this work, a process was developed for the separation of metal ions from synthetic sulfate leach liquor of laterite ores containing Fe(III), Al(III), Ni(II), Co(II), Ca(II), Mg(II), and Mn(II). First, Fe(III) and Al(III) were removed by precipitation of their hydroxides by adjusting solution pH and then Mn(II) was removed from the filtrate by oxidative precipitation with NaClO. Sequentially, Co(II) and Ni(II) from the filtrate containing Mg(II) and Ca(II) were separated by selective precipitation of CoS and NiS by adding Na2S solution, leaving Ca(II) and Mg(II) in the filtrate. The mixed precipitates of CoS and NiS were completely dissolved by 0.1 M HCl solution containing NaClO. Co(II) can be separated from Ni(II) present in the HCl solution by either oxidative precipitation with NaClO or selective extraction with saponified Cyanex 272. Optimum conditions for these procedures were obtained. Continuous experiments indicated that the purity of Co(II) and Ni(II) solutions was higher than 99%. [ABSTRACT FROM AUTHOR]

This study focuses on the use of H‐ZSM‐5 catalyst modified with transition metals for the conversion of ethanol into liquid fuel hydrocarbons. The HZSM‐5 catalyst was synthesized hydrothermally, and the transition metal (0.5 wt%) was incorporated by the incipient wetness impregnation method. The synthesized catalysts were tested in a fixed‐bed reactor at varying weight hourly space velocities (WHSVs) and temperatures to investigate their effects on the selectivity of the liquid hydrocarbon product. The pure and metal‐doped catalysts were characterized using XRD, FTIR, SEM–EDX, PSD, BET, N2 adsorption–desorption, and NH3‐TPD. The metal species were evenly dispersed on the catalyst support without affecting the porous framework significantly. The modification did not alter the morphology of the catalyst; however, the particle size was altered slightly. The pore distribution plot confirms the hierarchical porous framework of the catalyst. This unique feature facilitates internal diffusion and accelerates mass transfer, improving the selectivity and distribution of the liquid product. The catalytic evaluation showed ethanol conversion of more than 97% for all catalysts tested. A low space velocity (5 h−1) favored gaseous (C1‐C4) hydrocarbons, but more liquid products (C5+) were generated at 12 h−1 (at 350 and 400 °C), with metal‐doped catalysts showing higher selectivity (> 79%). In comparison with the unmodified catalysts, the metal‐doped catalysts enhanced the production of aromatics (benzene), with Ni/HZSM‐5 showing higher selectivity (> 4%). This study showed that the synthesized catalysts are active in the selective production of liquid hydrocarbon and improve the transformation of ethanol to fuel‐range hydrocarbons. [ABSTRACT FROM AUTHOR]

The ASTM International standard test method for freshwater mussels (E2455‐13) recommends 4‐week toxicity testing with juveniles to evaluate chronic effects on survival and growth. However, concerns remain that the method may not adequately address the sensitivity of mussels to longer term exposures (>4 weeks), particularly in relation to potential reproductive impairments. No standard method directly evaluates toxicant effects on mussel reproduction. The objectives of the present study were to (1) evaluate toxicity endpoints related to reproduction in fatmucket (Lampsilis siliquoidea) using two common reference toxicants, potassium chloride (KCl) and nickel (Ni); (2) evaluate the survival and growth of juvenile fatmucket in standard 4‐week and longer term (12‐week) KCl and Ni tests following a method refined from the standard method; and (3) compare the sensitivity of the reproductive endpoints with the endpoints obtained from the juvenile mussel tests. Reproductive toxicity tests were conducted by first exposing female fatmucket brooding mature larvae (glochidia) to five test concentrations of KCl and Ni for 6 weeks. Subsamples of the glochidia were then removed from the adults to determine three reproductive endpoints: (1) the viability of brooded glochidia; (2) the viability of free glochidia in a 24‐h exposure to the same toxicant concentrations as their mother; and (3) the success of glochidia parasitism on host fish. Mean viability of brooded glochidia was significantly reduced in the high KCl concentration (26 mg K/L) relative to the control, with a 20% effect concentration (EC20) of 14 mg K/L, but there were no significant differences between the control and any Ni treatment (EC20 > 95 µg Ni/L). The EC20s for viability of free glochidia after the additional 24‐h exposure and parasitism success were similar to the EC20s of brooded glochidia. The EC20s based on the most sensitive biomass endpoint in the 4‐week juvenile tests were 15 mg K/L and 91 µg Ni/L, similar to or greater than the EC20s from the reproductive KCl and Ni tests, respectively. When exposure duration in the juvenile tests was extended from 4 to 12 weeks, the EC20s decreased by more than 50% in the KCl test but by only 8% in the Ni test. Overall, these results indicate that a standard 4‐week test with juvenile mussels can prove effective for estimating effects in chronic exposures with different life stages although a longer term 12‐week exposure with juvenile mussels may reveal higher sensitivity of mussels to some toxicants, such as KCl. Environ Toxicol Chem 2024;43:1097–1111. © 2024 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Background Occupational exposure to metals such as nickel, chromium and cobalt can be associated with contact dermatitis, which can adversely affect an individual's health, finances and employment. Despite this, little is known about the incidence of metal-related occupational contact dermatitis over prolonged periods of time. Objectives To investigate the medically reported trends in the incidence of work-related contact dermatitis attributed to nickel, chromium and cobalt in the UK. Methods Incidence and trends in cases of occupational contact dermatitis caused by nickel, chromium or cobalt between 1996 and 2019 (inclusive), reported to the EPIDERM surveillance scheme, were investigated and compared with trends in the incidence of occupational contact dermatitis attributed to agents other than the aforementioned metals. A sensitivity analysis restricting the study cohort to cases attributed to only one type of metal was also conducted. Results Of all cases reported to EPIDERM during the study period, 2374 (12%) were attributed to nickel, chromium or cobalt. Cases predominantly comprised females (59%), with a mean (SD) age (males and females) of 38 (13) years. Cases were most frequently reported in manufacturing, construction, and human health and social activity industries. The most frequently reported occupations were hairdressing, and sales and retail (assistants, cashiers and checkout operators). The highest annual incidence rate of contact dermatitis was observed in females (2.60 per 100 000 persons employed per year), with the first and second peak seen in those aged 16–24 and ≥ 65 years, respectively. A statistically significant decrease in the incidence of occupational contact dermatitis attributed to metals over the study period was observed for all occupations (annual average change –6.9%, 95% confidence interval –7.8 to –5.9), with much of the decrease occurring between 1996 and 2007. Similar findings were obtained in the sensitivity analyses. Conclusions Over a period of 24 years, there has been a statistically significant decline in the incidence of metal-related occupational contact dermatitis in the UK. This could be attributed not only to improvements in working conditions, which have reduced metal exposure, but could also be due to the closure of industries in the UK that might have generated cases of contact dermatitis owing to metal exposure. [ABSTRACT FROM AUTHOR]

An electrolyte based on the deep eutectic solvent reline (a mixture of choline chloride and urea) was used for electrodeposition of coatings containing nickel and cerium. It was shown that a decrease in temperature and an increase in the concentration of cerium(III) ions in the plating bath lead to an increase in the content of cerium in the electrodeposits. Under certain conditions of electrolysis, it was possible to prepare coatings that contain nanocrystalline nickel with the inclusion of up to 40–59 wt.% cerium. The kinetics and reaction mechanism of hydrogen evolution on electrodeposited coatings in an aqueous alkaline medium of 1 M NaOH were studied in detail using the methods of Tafel analysis and electrochemical impedance spectroscopy. It was stated that a significant increase in the electrocatalytic activity of the electrodeposited material is observed with an increase in the content of cerium in the coating. A possible mechanism of the process (Volmer-Heyrovsky reaction pathway) was proposed and equivalent circuits were developed that adequately describes the registered impedance hodographs. A comparison of the results obtained in this work with literature data showed that the coating fabricated in reline-based electrolytes exhibit a higher content of cerium, and therefore a higher electrocatalytic activity towards the hydrogen evolution reaction than coatings produced from electrolytes based on ethaline (a eutectic mixture of choline chloride and ethylene glycol). [ABSTRACT FROM AUTHOR]

The nickel element doped holmium oxide (Ho2O3:Ni) transparent magneto‐optical ceramics were fabricated by vacuum sintering and the dopant impacts on structure features and Faraday effects were investigated. The starting oxide powders were synthesized by pyrolyzing the resulting layered holmium‐based hydroxide nanosheets prepared from a chemical precipitation route using the sodium hydroxide as precipitant at the freezing temperature. Upon high‐temperature sintering, the Nii••${\mathrm{Ni}}_i^{ \bullet \bullet }$ defect is introduced by Ni2+ substitution for Ho3+ to form the interstitial solid solution. The 1 at.% Ni2+ doped Ho2O3 ceramic sample exhibits an in‐line transmittance of ∼70.04% at 1 550 nm with a relative density of ∼99.88%, while more Ni2+ incorporation (e.g., 2‒5 at.%) even leads to a completely opaque state. The magneto‐optical transparent Ho2O3:1%Ni ceramic developed in this work has Verdet constants of ∼−195, −65, and −29 rad/(T·m) at 635, 1 064, and 1 550 nm, respectively, which are ∼1.8‐fold higher than the commercial terbium gallium garnet crystal or ∼1.4‐fold higher than the pure Ho2O3 ceramic. This material also possesses relatively large figure of merit of ∼14.6°/T at 1 064 nm and relatively high thermal conductivity of ∼7.5 W/(m·K) at room temperature. [ABSTRACT FROM AUTHOR]

The corrosion behavior and mechanism of nickel slag on semi‐rebonded magnesia‐chrome brick are investigated. The variations in the specimens before and after corrosion were studied using microstructure, phase composition, and thermodynamic simulations. The results reveal that at high temperatures, the metal oxides in nickel slag easily react with Cr2O3 to generate Cr‐spinel, and the isolation layer forms a continuous phase on the surface of the refractory. The appearance of the isolation layer causes the nickel slag corrosion process on semi‐rebonded magnesia‐chrome brick to shift from direct to indirect corrosion controlled by ion diffusion, effectively blocking the continuous penetration of Ca2+ and Si4+ in the slag inside the refractories. As a result, the semi‐rebonded magnesia‐chrome brick resists nickel slag corrosion extremely well. [ABSTRACT FROM AUTHOR]

In this study, a series of nickels supported on gamma alumina with a metal dosage ranging from 0.5 to 3 wt.% were prepared and employed as the catalysts. The effect of nickel dosage on material properties, reaction performance, and catalyst deactivation was investigated. At a low dosage, the nickel-free having low metal-support interaction contributed significantly to the total active site. The basicity of the material was enhanced along with the increase in nickel loading. The presence of active metal showed a great impact at the beginning leading to big improvements in feedstock conversion. However, beyond a nickel dosage of 2 wt.%, further additions did not noticeably influence the reaction performance. Regarding catalyst deactivation, different carbon species were observed on catalyst surface, depending on the nickel dosage. Catalysts with less than 2 wt.% nickel exhibited amorphous carbon as the dominant morphology on the spent catalyst. In contrast, catalysts with 2Ni/Al2O3 and 3Ni/Al2O3 compositions showed graphitic carbon as the main side product. These findings provide insights into the relationship between nickel dosage, catalyst properties, and catalytic performance in methane dry reforming. By understanding the effects of nickel loading on material properties and reaction behavior, researchers can optimize catalyst design and develop more efficient and stable catalysts for sustainable syngas production. [ABSTRACT FROM AUTHOR]

Processing CO2 into value–added chemicals and fuels stands as one of the most crucial tasks in addressing the global challenge of the greenhouse effect. In this study, we focused on the complex (dpp–bian)NiBr2 (where dpp–bian is di‐isopropylphenyl bis‐iminoacenaphthene) as a precatalyst for the electrochemical reduction of CO2 into CH4 as the sole product. Cyclic voltammetry results indicate that the realization of a catalytically effective pattern requires the three–electron reduction of (dpp–bian)NiBr2. The chemically reduced complexes [K(THF)6]+[(dpp–bian)Ni(COD)]− and [K(THF)6]+[(dpp–bian)2Ni]− were synthesized and structurally characterized. Analyzing the data from the electron paramagnetic resonance study of the complexes in solutions, along with quantum–chemical calculations, reveals that the spin density is predominantly localized at their metal centers. The superposition of trajectory maps of the electron density gradient vector field ∇ρr ${\nabla \rho \left({\bf r}\right)}$ and the electrostatic force density field Fesr ${{{\bf F}}_{{\rm e}{\rm s}}\left({\bf r}\right)}$ per electron, as well as the atomic charges, discloses that, within the first coordination sphere, the interatomic charge transfer occurs from the metal atom to the ligand atoms and that the complex anions can thus be formally described by the general formulae (dpp–bian)2−Ni+(COD) and (dpp–bian)2−Ni+. It was also shown that the reduced nickel complexes can be oxidized by formic acid; resulting from this reaction, the two–electron and two–proton addition product dpp–bian–2H is formed. [ABSTRACT FROM AUTHOR]