Low Nickel Content Research Articles

Metal-Supported Solid Oxide Co-Electrolysis Cells

Achieving a net-zero greenhouse gas emissions economy by 2050 is an ambitious target for the European Union to mitigate climate change. The development of carbon-neutral fuels with high energy-density is essential for the de-fossilization of the heavy transportation sector. Solid Oxide Electrolyser (SOE) technology could play a crucial role in Power-to-X applications aimed at facilitating the development of such fuels. Solid Oxide Electrolysis Cells (SOECs) boast high efficiencies in converting renewable electricity into chemical energy, in form of hydrogen or other high energy-density fuels. Most established SOEC configurations are electrolyte- or fuel-electrode-supported. Recently, Metal-Supported SOECs (MS-SOECs) have attracted great attention thanks to their cheaper materials and superior mechanical properties compared to traditional ceramic configurations.The European E-TANDEM project aims to enable the production of a carbon-neutral diesel-like e-fuel for the marine and heavy-duty transport sectors. Said e-fuel is produced from H2O, CO2, and renewable power in a once-through hybrid-catalytic process that integrates three sub-processes: electrocatalysis for e-syngas (H2+CO) production, thermocatalysis for hydrocarbon synthesis from syngas, molecular chemocatalysis to oxo-functionalize the hydrocarbons. In this study, the focus is on the first step of the conversion. High-temperature co-electrolysis of H2O and CO2 through MS-SOECs is investigated.Three SOECs were tested, denoted as cells A, B, C. State-of-the-art (SoA) ceramic Ni/YSZ (Nickel/Yttria Stabilized Zirconia) fuel-electrode-supported cell, used as reference.One type of MS-SOEC fabricated at DTU Energy, with metal/ScYSZ (Scandia-doped YSZ) fuel electrode infiltrated with Ni/GDC (Gadolinium-doped Ceria) (percolating nickel content).Another type of MS-SOEC fabricated at DTU Energy, with metal/LSFNT (lanthanum-strontium-iron-nickel titanate) fuel electrode, infiltrated with Ni/GDC (low nickel content, not percolating). The durability of these cells in co-electrolysis mode was investigated. The cells were tested under constant current density (0.5 A/cm2) for 500 hours. Mass spectroscopy was used (with cells B and C) to measure the outlet fuel composition throughout the tests.The tests were carried out at 650 °C and 1 atm, with a fuel electrode inlet gas mixture of 10:47:43 H2:H2O:CO2, and H2O-CO2 conversion of 37% (by Faraday equation). Under thermodynamic equilibrium conditions, the mixture gives a syngas H2/CO ratio of ca. 2 and negligible methane content, which is suitable for downstream e-fuel synthesis in the E-TANDEM framework.During test of cell A, the measurement of the lambda sensor placed downstream of the cell confirms that the outlet fuel composition corresponds to equilibrium, meaning that the desired syngas was obtained. With cells B and C, the outlet gas composition was measured by mass spectroscopy. The outlet H2/CO ratio was 2.17 with cell B, meaning that the outlet syngas composition was close to equilibrium, and 1.32 with cell C, meaning that it deviated from equilibrium. These findings demonstrate that the SoA fuel electrode, rich in nickel, promotes RWGS (Reversed Water Gas Shift) reaction, which leads to the equilibrium distribution of H2, H2O, CO, CO2. On the other hand, the much lower amount of nickel present in the fuel electrode of cell C is not sufficient to catalyse the RWGS to the extent of reaching the equilibrium composition.Cell A started the 500h durability test from 1237 mV and showed a degradation of 332 mV/1000h or 26.8%/1000h. Cell B started from 1322 mV and degraded with an average rate of 238 mV/1000h or 18%/1000h. Cell C showed a worse initial performance (1608 mV) and the degradation rate was significantly higher, 948 mV/1000h or 59%/1000h.Electrochemical Impedance Spectroscopy (EIS) was periodically carried out to follow the trends of resistance contributions of the cells. It revealed that for all cells the increase in total resistance was mainly attributed to polarization contributions. Cell A showed a small increase in ohmic resistance, which instead slightly decreased in cell B, i.e. there was an activation, and remained stable in cell C until an increased degradation after ca. 300 h of operation.Scanning Electron Microscopy (SEM) characterization was carried out to assess the long-term operation impact on the cells’ microstructure. SEM showed that, both in cells B and C, a dense chromia scale protected from corrosion the metal in the support and the fuel electrode. Signs of chromium migration via evaporation and precipitation in the fuel electrode were observed in cell C as agglomeration of chromia at the interface between electrolyte and fuel electrode. This work has been funded by the European Union under grant number 101083700 (E-TANDEM). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them.

Effects of heat treatment on the microstructure and corrosion behavior of manganese aluminum bronzes

Abstract Due to a much lower nickel content, manganese aluminum bronzes (MAB) are a cost-effective alternative to nickel aluminum bronzes (NAB). When the material is processed, different microstructures are observable in the material which have an impact on the corrosion resistance of MAB alloys. MAB samples were annealed at 900 °C and quenched in water. After that, annealing treatments at 600, 500, 400 and 300 °C for up to 24 h were performed and the samples were again quenched in water. Metallographic sections were prepared from all samples and potentiostatic corrosion tests at different potentials were performed in synthetic seawater. It was found that the sample annealed at 900 °C and quenched in water as well as those samples which underwent a second annealing treatment at low temperatures for shorter times exhibited a greater corrosion tendency than those undergoing a second annealing treatment at higher temperatures. X-ray diffraction measurements revealed that phase transformations and changes in grain size occurred during the annealing treatments. The increase in corrosion resistance as a result of annealing at higher temperatures is probably due to the strong intergrowth of the phases that are formed.

Behaviour of eccentrically loaded concrete-filled rectangular ferritic stainless steel tubular slender columns: Numerical modelling and design

Ferritic stainless steel achieves a lower and steady price level due to low nickel content compared to duplex and austenitic stainless steels. Accordingly, the combination of ferritic stainless steel tube and concrete will have better application prospects in corrosive marine environments. However, the structural application of concrete-filled ferritic stainless steel tube (CFFSST) members is still limited due to the absence of performance data and design guidelines. Accordingly, this paper aims to comprehensively investigate the behaviour of eccentrically loaded concrete-filled rectangular ferritic stainless steel tubular (CFRFSST) slender columns using the nonlinear finite element (FE) method, and develop a suitable design method. Two different material models were introduced to simulate corner and flat regions of rectangular ferritic stainless steel tube. Good consistency was found between the simulation and experimental results against the failure mode, ultimate load and moment, and axial load versus mid-height deflection curves for eccentrically loaded CFRFSST slender columns. This is followed by the mechanism analysis and parameter study of the studied CFRFSST columns, which revealed that the longitudinal stress and Mises stress show significant changes perpendicular to the loading line direction, while there is almost no change along the loading line direction. In addition, the initial stiffness and ultimate load increased by increasing the cross-sectional aspect ratio, yield stress and concrete strength, while they decreased as the eccentricity ratio, slenderness ratio and width-to-thickness ratio increased. The outputs of the FE analysis and existing experimental results were used to examine the applicability of current design codes for designing the studied CFRFSST columns. The results demonstrated an unexpected deviation generated in the design predictions. At the end, a new design method for eccentrically loaded CFRFSST slender columns was proposed which achieved better predictive consistency.

Why are oceanic arc basalts Ca-rich and Ni-poor? Insights from olivine-hosted melt inclusions from Kibblewhite Volcano in the Kermadec arc

Ankaramites, which are clinopyroxene-rich basalts with primitive whole-rock compositions (Mg# >65), are common in oceanic arcs and are characterized by high whole-rock CaO/Al2O3 (>1.0) ratios and olivine crystals with anomalously low nickel contents (<0.2 wt% NiO). These geochemical characteristics cannot be explained by the melting of ordinary mantle peridotite. However, their origin is critical for understanding the formation of primary magmas in oceanic arcs. Here, we investigated olivine-hosted melt inclusions (MIs) from ankaramites and magnesian andesites of the Kibblewhite Volcano in the Kermadec arc. The MIs from the ankaramites have similar major and trace element characteristics to the host rocks, indicating that the ankaramites did not result from an accumulation of mafic minerals but rather represent the primary magma in the Kibblewhite Volcano. The MIs from the magnesian andesites were hosted in forsteritic olivine xenocrysts with a wide range of NiO contents (Fo90–92; 0.13–0.39 wt% NiO) and have similar major element compositions to the ankaramites but exhibit a wide range of CaO/Al2O3 (0.85–1.54). The trace element characteristics of the MIs from the magnesian andesites do not match those of the host rocks, indicating that they are not primary melts of the magnesian andesites but primitive basaltic melts generated before the magnesian andesites formed.Interestingly, the CaO/Al2O3 ratio of MIs from the magnesian andesites was negatively correlated with the NiO content of their host olivines. This correlation suggests that the composition of the primary basaltic magmas of the Kibblewhite Volcano changed continuously from peridotite-derived to ankaramitic. This correlation could not be explained by grain-scale process, crustal anatexis, or contribution of slab-derived carbonate-rich fluids. Instead, we propose that this correlation can be explained by the interaction of the ascending primary basaltic melts with the lithospheric mantle. During melt-mantle interaction, the assimilation of clinopyroxene and fractionation of olivine and orthopyroxene caused the CaO/Al2O3 ratio to increase in the melt and the Ni content to decrease. Furthermore, because the magnesian andesites have low CaO/Al2O3 ratios and could be derived from a clinopyroxene-poor mantle lithology, the interaction between the melt and mantle may also be closely related to the origin of the magnesian andesites at Kibblewhite Volcano. This interpretation provides a new perspective on the origin of the oceanic arc ankaramites and why primary andesitic and basaltic magmas coexist in the Kibblewhite Volcano.

Influence of laser powder bed fusion and ageing heat treatment parameters on the phase structure and physical behavior of Ni-rich nitinol parts

This paper examines the effect of ageing temperatures (400, 500, & 600 °C) and times (30, 60, & 90 min) on Ni-rich NiTi samples produced via the Laser Powder Bed Fusion (L-PBF) technique. Variations in the process parameters of the L-PBF which were examined included laser power at 150W and 180W, and the scanning strategy at 500 mm/s and 1000 mm/s. Ageing heat treatment enabled setting the functional properties of phase change temperatures, stress-strain response, and phase change enthalpies. Samples aged at 400 °C were found to have much higher austenitic finish temperature (40–60 °C) whereas those aged at 600 °C had near-zero or sub-zero Af temperatures. This was due to the lower nickel concentration resulting from the higher heat treatment temperature. Samples heat-treated at 500 °C exhibited Af temperature which was near to the room temperature and showed co-existence of both austenitic and martensitic phases. It was also found that the crystallite size increased from 6 to 22 nm for an ageing temperature of 400 °C, to between 38 and 48 nm for an ageing temperature of 600 °C. The highest microhardness value of 380HV was recorded from the lower heat treatment temperature and the lowest microhardness of 270HV was recorded for samples heat-treated at 600 °C. This decrease in the microhardness values is attributed to the increased crystallite size of the aged samples at higher temperatures. This work identifies for the first time the novel ability to control NiTi phase change temperature and mechanical properties using ageing heat treatments which is critical for the materials application for personalised stents. Higher heat treatment temperatures were found to lead to larger crystallite sizes.

New experimental findings on the separation of cobalt and nickel from an ammonia-ammonium-based leach liquor using ammonium-saponified Cyanex 272

There is a need to improve cobalt and nickel recovery from industrial waste streams such as secondary leach solutions and rechargeable battery leach solutions due to the increasing economic value of these critical metals. Ammonia is an important lixiviant due to its limited environmental impact compared to acid based lixiviants, however, the subsequent selective extraction of cobalt and nickel from the leach liquor is a major challenge. This study presents new experimental findings on the treatment of a Base metal Refinery (BMR) secondary leach liquor that contains high concentrations of ammonia and ammonium sulphate, and low concentrations of cobalt (∼442 mg/L) and nickel (∼1624 mg/L) using partially saponified Cyanex 272. New knowledge that can be applied in the treatment of ammonia based leachates from various industrial wastes that contain residual cobalt and nickel is presented herein. The investigation was conducted through the determination of the optimum extraction temperature, percentage saponification, and organic to aqueous ratios. Partial saponification of Cyanex 272 increased ammonia-metal complex stability at the interphase and this limited cobalt extraction between 30 °C and 50 °C. However, a high cobalt extraction percentage, and a high separation factor of 94.07 %, and 1189.76 respectively were achieved at 60 °C, 20 % saponification, and 0.5 O/A loadings in a single contact. A second-stage batch extraction produced a nickel aqueous stream with no cobalt. Stripping of the loaded organic phase with dilute sulphuric acid produced a pure cobalt aqueous stream. Further, the extractant was successfully regenerated post stripping. Overall, partial ammonium-saponification increased the extent of cobalt extraction, and selectivity. The novel process conditions reported herein can be used to design sustainable cobalt-nickel separation processes.

Failure analysis on fracture causes of stainless-steel studs in seawater system of nuclear power plants

Nine of the twelve B8M stainless steel studs on the flange of a seawater pipeline isolation valve of a nuclear power plant were encountered with premature fracture during service. To find out the cause of the fracture failure, the fracture studs were comprehensively detected and analyzed by means of appearance morphology analysis, chemical composition analysis, mechanical properties testing, microstructure testing, and fracture micro-area analysis. The results show that the main reasons are as follows: (1) The solid solution temperature of the raw materials for processing bolts is low, so the carbides are not fully dissolved and distributed in a mesh along the grain boundary. Thus, the chromium-poor near the grain boundary forms, resulting in the mechanical properties of the bolts weakening. According to the experiment, it was found that the corrosion resistance of the bolts is weak due to the low nickel content. Carbon easily precipitates at the grain boundary and forms Cr23C6 with chrome, which weakens the bonding strength of the grain boundary and causes the bolt to break along the grain.

Postprocessing of tungsten carbide‐nickel preforms fabricated via binder jetting of sintered‐agglomerated powder

AbstractThis study binder jets a tungsten carbide‐nickel (WC‐Ni) sintered‐agglomerated composite powder, and postprocesses the preforms using an initial sintering step followed by a hot isostatic pressing (HIP) step. The effects of sintering temperatures, sintering durations, and HIP temperatures on notable properties (e.g., porosity, microstructure, hardness, and oxidation behavior) are quantified. The highest average relative density produced in this study was 96.8%, and volumetric shrinkage of these coupons was about 64%. Microstructural characterization shows that the WC grains are homogenously distributed throughout the nickel matrix and grow to an average diameter of 1.6 (a 60% increase) during processing. X‐ray diffraction patterns indicate that no unwanted products were formed. Processed coupons achieved a maximum hardness of 54 Rockwell C, limited by their internal porosity. Oxidation tests result in the production of WO3 and NiWO4 at temperatures above 600°C. Methodologies and results from this study can be leveraged to additively manufacture highly dense, geometrically complex WC‐Ni parts with small carbide grains, low nickel content, desirable microstructure, and suitable functional properties.

Easy and Scalable Syntheses of Li1.2Ni0.2Mn0.6O2

Solid-state and sol-gel syntheses were selected as easy and scalable methods to prepare a lithium-rich cathode material for lithium-ion batteries. Among the extended family of layered oxides, Li1.2Ni0.2Mn0.6O2 was chosen for its low nickel content and the absence of cobalt. Both synthesis methods involved two heating steps at different temperatures, 600 and 900 °C. The first step is needed to decompose the metal acetates, which were selected as precursors, and the second step is needed to crystallise the material. To obtain a material with well-defined defects, the rate of heating and cooling was carefully controlled. The materials were characterised by X-ray diffraction, SEM coupled with EDS analysis, and thermal analysis and were finally tested as cathodes in a lithium semi cell. The solid-state synthesis allowed us to obtain better structural characteristics with respect to the sol-gel one in terms of a well-formed hexagonal layer structure and a reduced Li+/Ni2+ disorder. On the other hand, the sol-gel method produced a material with a higher specific capacity. The performance of this latter material was then evaluated as a function of the discharge current, highlighting its good rate capabilities.

Abstract 084: Intracranial Onyx Resolute Stenting In Idiopathic Intracranial Hypertension Patient With Pre‐existing Nickel Allergy: Case Report

Introduction Idiopathic intracranial hypertension (IIH) is a pathology involving an increase in intracranial pressure leading to symptoms including papilledema, tinnitus, and elevated cerebrospinal fluid opening pressure. Recent research has identified venous sinus stenosis as a cause of IIH, a common treatment of which is venous stenting and angioplasty. An adverse event of this procedure is in‐stent stenosis (ISS), due to either neointimal hyperplasia or hypersensitivity to an element in the stent. There has been speculation regarding whether nickel in intracranial stents is a cause of concern, due to its potential to cause a Type IV hypersensitivity reaction and ISS, which is an indicator of future stroke. The purpose of this case report is to determine if the cobalt‐based alloy Onyx Resolute intracranial stents can safely treat IIH in patients with allergic contact dermatitis to nickel. Methods We present a 38‐year old woman who presented with migraines and IIH with papilledema and severe pulsatile tinnitus. Headaches had been present for 5‐10 years. Ophthalmology consult revealed bilateral papilledema, upon which an MRI and MRV revealed venous stenosis. There was a 17mmHg pressure gradient measured in the patient. Patient could not tolerate acetazolamide, with kidney stones and loss of sheen in hair. Cerebral angiogram indicated right transverse‐sigmoid junction stenosis and atretic left venous sinus. The patient had an Onyx Resolute stent placed in the right transverse sigmoid junction. The Onyx Resolute stent is a Zotarolimus‐eluting stent made up of a cobalt‐based shell and a platinum‐Iridium core and is not recommended for patients with a hypersensitivity to nickel, cobalt, or chromium, but has a lower nickel content than a self‐expanding stent. Results Patient underwent cerebral angiogram, revealing right transverse‐sigmoid junction stenosis with a 17mmHg pressure gradient. Stenting and angioplasty were performed; this reduced the venous sinus pressure in the R transverse sinus (pre‐stenotic segment) from 43 mm Hg to 24 mm Hg with resolution of the R transverse‐sigmoid junction pressure gradient. Patient was treated with prasugrel (Effient) for one month. At the one‐month follow‐up, the patient reported an improvement of symptoms, with near‐resolution of her prior headaches in terms of severity and frequency following her procedure. Visual acuity is at baseline, pending formal follow‐up assessment for papilledema. Follow‐up CT Head Venogram with and without contrast showed a patent R transverse to sigmoid venous stent. The patient was continued on aspirin 81mg daily and prasugrel 5mg daily and is to continue follow‐up with yearly ophthalmologic exams. Conclusion Although there is speculation regarding the use of metal intracranial stents in patients allergic to nickel, our patient has shown that it is safe to use the Onyx Resolute intracranial stent despite a pre‐existing nickel hypersensitivity.

Electrogenerative Process as an Alternate Technique for Nickel Recovery from Its Sulphate Solution at Low Concentration

In this study, a static batch reactor equipped with three-dimensional (3-D) carbon felt (CF) as cathode material was fully optimized to recover a low nickel concentration from its sulphate solution. Nickel recovery was performed using several nickel concentrations ranging from 50, 100, 250, 400 and 500 mg/L. Moreover, within 30 min of electrogenerative operation, it was discovered that the recovery of nickel achieved &gt; 90 % in acidic conditions. At last, the deposition of nickel into CF was further investigated by scanning electron microscopy (SEM) to visualize the surface morphology of nickel on CF.

Application of vacuum membrane distillation process for lithium recovery in spent lithium ion batteries (LIBs) recycling process

The feasibility of using vacuum membrane distillation (VMD) for lithium recovery by concentrating the discharged leachate from spent lithium ion batteries (LIBs) recycling process was evaluated. The performance of VMD was compared with that of direct contact membrane distillation (DCMD) in terms of water flux, concentration rate, membrane wetting, and economic feasibility. VMD achieved a higher volume concentration factor (VCF) of 45 compared to the VCF of 25 achieved by DCMD in the LiCl feed solution. In the Li2SO4 feed solution, VMD and DCMD were concentrated to VCF15 and VCF 17, respectively, before wetting occurred. The stability of the MD process was verified using feed solutions containing nickel and manganese, which are cathode materials that can cause scaling even at low concentrations. Low concentrations of nickel and manganese did not significantly affect the maximum VCF or wetting; however, high concentrations of nickel and manganese affected the stability of the MD process. VMD exhibited a higher flux and 32 % lower thermal energy consumption than DCMD. Furthermore, the expected cost of Li2CO3 production with VMD for leachate concentration was $8.31–10.65/kg. The VMD concentration process is a feasible option for recovering lithium from the discharged leachate from spent LIBs recycling process.

Extraction of ferronickel concentrate from laterite nickel ore by reduction roasting-magnetic separation using spent cathode carbon

Laterite nickel ores are the most important raw materials in nickel production, but processing laterite nickel ores with a low nickel content is difficult. Annually, the aluminum electrolysis industry produces a large amount of spent cathode carbon containing toxic substances, such as fluorine and cyanide, but a considerable amount of it cannot be effectively utilized. The purpose of the present study is to prepare ferronickel concentrates by reduction roasting–magnetic separation using spent cathode carbon as a reducing agent. Different factors affecting the agglomeration and growth of metal particles are studied. The migration of fluorine and the aggregation behavior of iron and nickel after the addition of spent cathode carbon and CaO are studied. Results show that the nickel grade in the ferronickel concentrate is 5.4 wt%, the nickel recovery rate is 84.80%, the iron grade is 67.93 wt%, and the iron recovery rate is 89.91%. Efficient recovery and utilization of nickel and iron in laterite nickel ores are realized. Waste utilization of spent cathode carbon thus provides a new method for the treatment of spent cathode carbon.

Modification of NMC811 with titanium for enhanced cycling and high-voltage stability

LiNi1-x-yMnxCoyO2 (NMC) with a nickel content of ≥80% is currently considered one of the most promising lithium-ion battery cathode materials for applications that require both a high energy density and reasonable costs. However, its widespread use has so far been limited by its inherently lower structural stability and higher surface reactivity compared to NMC materials with a lower nickel content. Here, we explore wet-chemical titanium-based bulk and surface modifications to improve the cycling and high-voltage stability of NMC811. We find that both doping and coating with titanium improve cycling stability. For example, the capacity retention of graphite/NMC811 full cells cycled for 200 cycles between 2.8 and 4.4 V at C/3 improves from 86.1% for the pristine NMC811 to 89.4% and 91.5% for the doped and coated samples, respectively. Combining doping and coating in a two-step process results in a material with the most balanced properties in terms of capacity, cycling stability, rate performance, and high-voltage stability.

Catalytically Active and Carbon-Resistive Anode Catalyst for Solid-Oxide Fuel Cells Operated at Low Temperatures (500–600 °C)

The development of active catalysts is always challenging in the field of energy devices. In this work, Li-doped, Ni–Cu-based, and Ni-free nanocomposite anode catalysts are synthesized and studied for solid-oxide fuel cells (SOFCs) operated at a low temperature using hydrogen and biogas as fuels. The catalysts with compositions Ni0.6Li0.2Cu0.2-oxide/La0.2Ce0.8O2-δ (NLC622-LDC), Ni0.2Li0.2Cu0.6-oxide/La0.2Ce0.8O2-δ (NLC226-LDC), and Ni0.0Li0.2Cu0.8-oxide/La0.2Ce0.8O2-δ (NLC028-LDC) are synthesized using the glycerol-assisted gel combustion route (GGCR). The structural analysis revealed the cubic structure of metallic oxide materials such as NiO and CuO phases while the cubic fluorite structure of CeO2 as an ionic oxide phase. The optical band gaps (Eg’s) of anode catalysts NLC622-LDC, NLC226-LDC, and NLC028-LDC are found to be 2.08, 2.29, and 2.37 eV, respectively. Furthermore, the anode catalyst with a higher nickel concentration shows better electrical conductivity and a lower activation energy of 3.47 S cm–1 and 0.67 eV at 600 °C, respectively, as compared to those of a nickel-free anode catalyst with lower nickel content. The electrochemical behavior of nanocomposites is studied at 600 °C using Nyquist plots. Electrochemical impedance analysis is carried out to see the effect of hydrocarbon fuel like biogas at the anode side. Finally, the electrochemical performance of NiLiCu-LDC catalyst-based fuel cells is tested under hydrogen and biogas fuels. Overall, the fuel cell based on the NLC622-LDC anode catalyst has higher OCV and power density with both fuels, hydrogen and biogas. Therefore, NLC622-LDC is a highly catalytically active anode catalyst which demonstrated significantly better performance for SOFCs operated at a low temperature (500–600 °C) without any carbon resistance.

Association between prenatal exposure to trace elements mixture and visual acuity in infants: A prospective birth cohort study

BackgroundPrenatal environmental factors may affect the development of the offspring and can bring long lasting consequences to the offspring's health. To date, only few studies have reported inconclusive association between prenatal single trace element exposure and visual acuity, and no studies have investigated the association between prenatal exposure to trace elements mixture and visual acuity in infants. MethodsIn the prospective cohort study, grating acuity in infants (12 ± 1 months) was measured by Teller Acuity Cards II. Concentrations of 20 trace elements in maternal urine samples collected in early-trimester were measured by Inductively Coupled Plasma Mass Spectrometry. Elastic net regression (ENET) was applied to select important trace elements. Nonlinear associations of the trace elements levels with abnormal grating were explored using the restricted cubic spline (RCS) method. The associations between selected individual elements and abnormal grating acuity were further appraised using the logistic regression model. Then Bayesian Kernel Machine Regression (BKMR) was used to estimate the joint effects of mixture and interactions between trace elements combining with NLinteraction. ResultsOf 932 mother-infant pairs, 70 infants had abnormal grating acuity. The ENET model produced 8 trace elements with non-zero coefficients, including cadmium, manganese, molybdenum, nickel, rubidium, antimony, tin and titanium. RCS analyses identified no nonlinear associations of the 8 elements with abnormal grating acuity. The single-exposure analyses using logistic regression revealed that prenatal molybdenum exposure possessed a significantly positive association with abnormal grating acuity (odds ratio [OR]: 1.44 per IQR increase, 95% confidence interval [CI]: 1.05, 1.96; P = 0.023), while prenatal nickel exposure presented with a significantly inverse association with abnormal grating acuity (OR: 0.64 per IQR increase, 95% CI: 0.45, 0.89; P = 0.009). Similar effects were also observed in BKMR models. Moreover, the BKMR models and NLinteraction method identified potential interaction between molybdenum and nickel. ConclusionsWe established that prenatal exposure to high concentration of molybdenum and low concentration of nickel was associated with the increased risk of abnormal visual acuity. Potential interaction may exist between molybdenum and nickel on abnormal visual acuity.

Onsite detection of cadmium and nickel using gold nanospheres and nanotriangles capped with Cyclea peltata phytochemicals

Small-sized gold nanospheres and nanotriangles (CPAuNPs) were synthesized to visually identify low concentrations of cadmium and nickel (20 ppm) in polluted water samples. Three factors i.e Cyclea peltata extract concentration (X1), temperature (X2), pH (X3) and agitation speed (X4) were optimized for maximum CPAuNPs synthesis by central composite design. The optimized conditions were found to be CP extract concentration of 24.20%, pH of 7.68 and agitation speed of 43 RPM at which maximum yield of 0.412 g/L was obtained with a fold increase of 1.42 as compared to unoptimized conditions. Gold nanospheres were in the size range of 25–36 nm and nano triangles of 100–140 nm with zetapotential of −31.8 mV. The synthesized CPAuNPs demonstrated good selectivity for visual detection of cadmium and nickel at ppm levels, where the colour of CPAuNPs changed from pink to purple. Upon interaction of CPAuNPs with Cd+3 and Ni+2 in the varied concentration ranges, a maximum red shift was seen at 20 ppm, which confirmed agglomeration. The variation in absorbance ratio (A640nm/A523nm) for Cd+3 and (A610nm,/A523nm) for Ni+2 showed linearity upto 50 ppm with respect to increased concentration in both the cases with R2 = 0.926 in case of Cd+3 and R2 = 0.950 for Ni+2. Hence, a portable low-cost detection kit for specific heavy metals could be constructed, employing this plant reduced nanospheres, for on-site detection sensing of cadmium and nickel in industrial effluents upto 20 ppm limits.

The influence of Ni on the composition, structure and properties of Ti-Cr-N coatings

The influence of nickel on the structure and properties of Ti-Cr-N ion-plasma coatings obtained by arc-PVD method has been studied. With a nickel content of up to 11.9 at. %, the coating consists of Cr2N, Ti1 – xCrxN, and metallic Ni. Upon further increase in Ni concentration in the coating, intermetallic compound Ni3Ti is formed. The structure of the coatings was studied using the transmission electron microscopy. The coatings of Ti-Cr-N system are characterized by a columnar structure, in the columns of which Ti1 - xCrxN and Ti1 - yCryN (x &gt; y) sublayers, being several nanometers thick and containing variable concentration of titanium and chromium, as well as Cr2N sublayers of about 25 nm are formed due to the complete solubility of TiN and Cr2N and the planetary rotation of the substrates, resulting in layer-by-layer stacking of the components of the evaporated cathodes. This structure remains intact in coatings of Ti-Cr-N-Ni system with a low nickel concentration (on the order of tenths of at. %). However, upon that, the column size refinement and an increase in biaxial compressive stresses from 6.7 to 9.7 GPa are observed, which results in an increase in hardness from 30 to 42 GPa. The coatings with a high nickel content are characterized by a multilayer architecture with an equiaxed polycrystalline structure of nanograins in layers. As Ni concentration increases, the hardness of the coating decreases to 16.7 GPa, which is associated with an increase in the fraction of relatively soft nickel in the coating and a decrease in macrostresses to -0.6 GPa. Upon that, the wear intensity increases from 3·10-15 to 5·10-15 m3/(N·m). The studied coatings of Ti–Cr–N and Ti–Cr–N–Ni systems are resistant to adhesive and cohesive destruction. With an increase in the nickel content upon measuring scratching, the destruction of the coatings occurs exclusively due to the plastic deformation.

A Hydrothermal Phase Diagram for the Low-Temperature Synthesis of Nonstoichiometric Nickel Ferrite Nanoparticles

Corrosion products in pressurized water reactors are challenging to study in situ, yet understanding their properties is key to improving reactor performance and radiation reduction. In this study, a hydrothermal synthesis technique was used to produce nickel ferrite (NiFe2O4) particles from goethite (α-FeOOH) and nickel nitrate hexahydrate [Ni(NO3)2 6H2O] in the presence of sodium hydroxide (NaOH). X-ray diffraction was used for phase identification, with scanning electron microscopy used for particle shape and size analysis. By varying the [Ni]:[Fe] ratio of the precursors and synthesis temperature between 100°C to 250°C, a phase diagram was developed to determine the stability field in both composition and temperature for obtaining a single-phase, nonstoichiometric nickel ferrite product. The compositional boundaries of the single-phase region of the diagram are a function of temperature, consistent with the increased solubility and reaction rates at temperatures above 125°C. The single-phase nickel ferrite encompasses [Ni]:[Fe] ratios in a very narrow range at 150°C, only 0.35 to 0.375, but widens as a function of temperature and reaches its greatest breadth at 250°C. At this temperature, a single-phase product is obtained for a range of starting compositions from 0.30 to 0.425. Outside of this window, additional nanoparticles are obtained whose identity and composition vary with both temperature and starting mixture. On the lower nickel content side of the single-phase region, the mixture contains either unreacted goethite (for temperatures below 200°C) or hematite (α-Fe2O3) at 200°C or higher. On the Ni-rich side of the single-phase region, theophrastite [β-Ni (OH)2] was obtained along with the nickel ferrite, at all temperatures studied. The single-phase window was widest at 250°C, resulting in nickel ferrites with a Ni mole fraction between 0.23 and 0.31.

Influence of temperature and stress state on the TWIP behavior of 201LN and 316LV austenitic stainless steels

The present results analyzed deformation behavior under tension and compression of two different austenitic stainless steels: AISI 201LN, with low nickel content and stabilized with Mn and N; and AISI 316LV, stabilized with Ni and with low content of interstitial atoms. Mechanical tests were performed at a strain rate of 10−3 s−1 and at temperatures varying from −100 to 600 °C to yield comparable values of the stacking fault energy (SFE). The resulting microstructure was analyzed by X-ray diffraction and EBSD. The stress-strain curves were analyzed using the Kocks-Mecking (K-M) approach. For comparable stacking fault energies, temperature enhances the thermal activation effects that led to lower fraction of mechanical twins in the 201LN compared with the 316LV. The crystallographic re-orientation followed the flow rule irrespective of the temperature and deformation mechanism: tension and compression experiments showed the ⟨111⟩ or ⟨110⟩ orientation with the tension axis, respectively. In tension, the dislocation storage and recovery factors of the K-M model were larger than in the compression and the amount of stored dislocations and crystallite size reflect these effects. In the compression, the TWIP effect was reduced for the 316LV and suppressed for the 201LN.