Nickel Cations Research Articles

Seasonal controls on stream metal(loid) signatures in mountainous discontinuous permafrost

We assess physical and chemical processes driving seasonal fluctuations in dissolved (<0.45 μm) trace metal(loid) concentrations in subarctic streams in discontinuous permafrost. Our analysis integrates multiple years of stream hydrometric and geochemical data with geochemical analyses of bedrock, permafrost, and active-layer samples. Three principal flow regimes govern stream hydrology: winter baseflow, spring freshet, and summer high flows. Metal(oid) concentrations in streams respond seasonally to these flow regimes. Baseflows are dominated by discharge of circumneutral-pH groundwater draining fractured bedrock. This discharge acts as a source of metals found as oxyanions or neutrally charged complexes, such as uranium and molybdenum. High stream flows are associated with peak concentrations of aluminium, cobalt, copper, iron, nickel, titanium, and vanadium. Concentrations of the metal cations aluminium, cobalt, copper, nickel, and titanium peak during freshet, when infiltration of snowmelt through organic-rich and moderately acidic soils favors their complexation with dissolved organic carbon. Concentrations of vanadium peak during summer high flows, likely reflecting flow through mineral soils in the active layer and involving reductive dissolution of iron(III)-(oxyhydr)oxides. The seasonal variation of arsenic concentrations is complex; at the majority of catchments it is sourced from shallow flowpaths in the active layer, but it can also be locally associated with discharge of deeper bedrock groundwater, which is spatially constrained by the presence of permafrost. Based on our analysis, we present a conceptual model that describes the flowpaths and processes governing metal(loid) release to streams in discontinuous permafrost. This model provides a framework upon which we consider changes in metal(loid) export into water resources in the context of thawing permafrost.

Maize cob-derived activated carbon as an adsorbent for the removal of nickel (II) cation from aqueous solution: optimization and kinetic studies

Adsorption performance of maize cob-derived activated carbon (MCAC) for the removal of nickel (II) from solution was investigated in the present study. The MCAC was prepared by adsorbent chemical activation method. Afterwards, the MCAC was characterized and utilized as the adsorbent for batch adsorption process. Initial adsorbate concentration, contact time and adsorbent dosage were considered as the independent variables for the adsorption process. The experiments were designed based upon central composite design (CCD) of response surface methodology with the aid of Design Expert. The experimental data were fitted into a model using MATLAB regression analysis, and the developed model was later simulated to obtain the operation parameters that will give the optimum removal efficiency. The analysis of variance (ANOVA) revealed that all the considered independent process variables had significant effect on the adsorption process. The simulated response from MATLAB gave 97.113% removal efficiency of nickel (II) on experimental validation at optimum conditions of 9.75 mg/L initial nickel (II) concentration, 120 min contact time and 0.803 g adsorbent dosage. This result correlates with CCD that predicted 97.6154% nickel (II) removal efficiency. The experimental data were observed to be best fitted to pseudo-second-order kinetic model which showed that the process is chemisorption controlled. Hence, it may be concluded from the present data that MCAC is highly effective for the removal of Ni(II) from aqueous solution and the highly generated agricultural waste (Maize cob) can the easily modified as a adsorbent.

Preparation of amide oxime type surfactants and the chelation of copper and nickel cations

Preparation of amide oxime type surfactants and the chelation of copper and nickel cations

Free‐Standing Tunnel‐Structured MnO2 Nanorods‐Doped with Nickel and Cobalt Cations as Bifunctional Electrocatalysts for Zn–Air Batteries

AbstractThe rational design of the electrocatalysts is paramount to alleviating the global energy and environment crisis. Despite a bright future of MnO2 shown in energy storage and conversion, the intrinsic low electrical conductivity glooms its application in electrocatalytic reactions like oxygen reduction/evolution reactions (ORR/OER). The doping strategy is applied to equip the self‐supported MnO2 with enhanced ORR/OER and zinc‐air battery performance. In this work, a class of free‐standing MnO2 nanorods arrays on carbon paper‐doped with either cobalt or nickel cations are engineered through a simple hydrothermal method. The substitutional doping by Co or Ni that partly replaces the Mn ions in the [MnO6] octahedra brings about the Jahn–Teller distortion that exhibits excellent catalytic performance for ORR and OER. Indeed, the ORR performance reveals that the doping resulted in more positive half‐wave potential (by &gt;20 mV), higher limiting current densities, and an electron transfer number close to four. As for the OER, the doping not only decreases the overpotential at 10 mA cm−2 but also brings about an enhancement in the current density at 1.76 V six times greater than with the undoped MnO2 catalyst. An optimal concentration of 0.25 in the molar ratio Co/Mn or Ni/Mn is discovered based on the ORR/OER bifunctionality. Homemade rechargeable Zn–air aqueous batteries assembled with doped MnO2 deliver higher peak power density, higher specific capacity, lower charge voltage, lower charge/discharge voltage, and robust stability.

Fe3O4@SiO2@NiAl-LDH microspheres implication in separation, kinetic and structural properties of phenylalanine dehydrogenase

Fe3O4@SiO2@NiAl-LDH three-components microsphere contains a Fe3O4@SiO2 magnetic core and a layered double hydroxide with nickel cation provide the binding ability to (His)-tagged-protein and exhibits high performance in protein separation and purification. The morphology and chemistry of the synthesized Fe3O4@SiO2@NiAl-LDH microspheres were characterized by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), vibrating sample magnetometer (VSM), Dynamic light scattering (DLS). Purified enzyme was assesed with SDS-PAGE (sodium dodecyl sulfate–polyacrylamide gel electrophoresis and intrinsic fluorescence spectroscopy. In this study, the separation of phenylalanine dehydrogenase (PheDH) by Fe3O4@SiO2@NiAl -LDH was performed and the effect of microsphere was investigated on the kinetic and structural properties of PheDH. After purification, kinetic parameters such as Km, Vmax, Kcat, kcat/Km, optimum temperature, thermal stability, and and activation energy were evaluated and compared according to the mentioned methods. The interaction between the enzyme and the microsphere displayed a high performance in protein binding capacity. The results also revealed that the kinetic parameters of the enzyme changed in a dose-dependent manner in the presence of a microsphere. Moreover, the results of intrinsic fluorescence and Circular Dichroism (CD) confirmed the structural changes of the protein in the interaction with the microsphere.

Can Metal Cations Electrocatalyze Sulfur Redox Reaction and Suppress Polysulfide Shuttle?

AbstractIn lithium‐sulfur (Li−S) batteries, sulfur undergoes various changes. It switches between cyclic structure and linear structure. The charge on the sulfur varies between a neutral state and a negative charge‐bearing state. Due to these changes, the sulfur/polysulfide dissolves in the battery electrolyte. Furthermore, the kinetics of the sulfur redox reaction is sluggish. Therefore, a material that can suppress sulfur/polysulfide dissolution and electrocatalyze sulfur redox reaction is needed. We hypothesize that the polysulfide dissolution can be suppressed if the host exhibits polyvalent electrostatic attraction. Polysulfide is a negative charge‐bearing molecule; hence the host must comprise multiple positive charges. Nickel cations with other heteroatoms have been explored as a host in Li−S batteries. The heteroatoms impart additional interactions. The easier way to circumvent the effect of heteroatoms is the addition of metal salts. However, metal salts can either exhibit monovalent or divalent attraction with polysulfides. Those interactions are weak and we must have polyvalent interaction. Towards this objective, we have designed and synthesized a material that comprises multiple divalent cations that is also devoid of heteroatoms. The Li−S batteries fabricated using the metal cation immobilized graphene showed a maximum specific capacity of 1022 mAh/g at 0.1 C rate. Among the metal cations, nickel cations showed better performance than cobalt cations. Thus, we demonstrate that metal cations immobilized on Graphene can efficiently electrocatalyze the sluggish sulfur redox reaction and suppress the polysulfide dissolution.

MICROBIAL BIOREMOVAL OF DIVALENT TOXIC METALS

The problems of polymetallic wastewater treatment from mining enterprises as well as the accumulation of organic waste are acute worldwide. The application of any existing methods of wastewater purification is ineffective and impossible due to the huge volumes and high concentrations of metals. Similarly, modern methods are ineffective for the treatment of huge amounts of organic waste. Therefore, there is a necessity to develop novel environmental biotechnologies providing the simultaneous degradation of organic waste and detoxification of toxic metals. The purpose of the work was to theoretically substantiate and experimentally confirm the possibility of toxic divalent cations removal using dissimilatory sulfate reduction via anaerobic fermentation of ecologically hazardous model organic waste. Colorimetric and potentiometric methods were used for pH and redox potential measurement; volumetric and chromatographic methods – to control volume and composition of synthesized gas; permanganate method – to determine the concentration of dissolved organic carbon (DOC); photocolorimetric method via the qualitative reaction with Nessler’s reagent was used to determine the concentration of ammonium ions. The Co2+ and Ni2+ content in medium was determined by a colorimetric method with 4-(2-pyridylazo)resorcinol (PAR). Fermentation parameters were calculated with the use of mathematical and statistical ones. Modified Postgate B medium with different sources of carbon and energy (potatoes, alanine, and meat) was used for cultivation of dissimilatory sulfate reducing bacteria. The anaerobic microbiome obtained from the sludge of methane tanks showed high efficiency to remove Co2+ and Ni2+ from the liquid medium. The highest efficiency (100% in 9 days) was observed when alanine was used as a source of carbon and energy. The slowest metal precipitation process occurred using meat (20 days). Also, the use of a protein substrate did not provide the expected alkalinization of the medium, which could significantly accelerate the process of metal precipitation. The precipitation of cobalt and nickel cations during the hydrogen fermentation of potato starch was complicated by acidification of the medium, but it was equally effective when the pH was adjusted. The proposed approach, the slow dissimilatory sulfate reduction, due to the sparingly soluble calcium sulfate as electron acceptor, can be used as a basis for the development of new biotechnologies for the treatment of wastewater contaminated with divalent heavy metals with the simultaneous treatment of ecologically hazardous compounds.

Effect of sodium and yttrium co-doping on electrochemical performance of LiNi0.8Co0.15Al0.05O2 cathode material for Li-ion batteries: Computational and experimental investigation

LiNi0.8Co0.15Al0.05O2 (NCA) has attracted a lot of attention owing to its high voltage, specific energy density, and specific capacity. However, the cycle durability of the NCA material is still a challenge. Oxygen evolution, migration of nickel cations to the lithium layers (cation mixing), and the destruction of the layered structure of NCA are the most important reasons for thermal and structural instability, reducing capacity, and increasing impedance. Doping is one of the most effective ways to improve the thermal and structural stability of the NCA. In this study, the addition of sodium (Na) on Li-site and yttrium (Y) on metal-site, as well as the simultaneous addition of these elements to NCA material, were investigated experimentally and theoretically. For the first time, we proposed a framework for parameterization of the structural and thermal stability of NCA during the lithiation/delithiation process in terms of first-principle density functional theory (DFT) calculations. It is shown that variation in the Bulk modulus can reflect structural responses, and the calculated Bader charge on oxygen atoms is directly connected to thermal stability concerns. The computational results confirmed the positive effect of Na+ and Y3+ on the structural and thermal stability of the NCA cathode systematically. Following those outcomes, different percentages of the dopants were added to the cathode material experimentally, and electrochemical tests such as cyclability, electrochemical impedance spectroscopy, cyclic voltammetry, and rate capability were performed. The electrochemical tests revealed that in single-doped samples, the optimal amount of Na+ and Y3+ was 0.5 % (mol%), and in co-doped samples, 0.5 % of each dopant (0.5Na-0.5Y-NCA) produced the best results. The optimal 0.5Na-0.5Y-NCA sample retained 92.34 % of its capacity after 100 charge and discharge cycles at a rate of 0.5C, compared to 67.11 % for the pristine NCA. The cooperative addition of sodium and yttrium with different mechanisms such as reducing released oxygen, reducing the formation of insulating compounds, increasing the diffusion coefficient, reducing charge transfer resistance, and improving structural and thermal stability demonstrated synergistic effects on stabilizing the layered structure and improving cycling performance. The underlying mechanisms of observed experimental improvements were interpreted and discussed according to computational outcomes.

Preparation of Some Complexes of Nickel (II) and Copper (II) Metals with Macrocyclic Ligand, 1,7,10,16- tetraaza-8, 9, 17, 18-dibenzo - 3,4,5,12,13,14 -Difuranyl Cyclo Octadeca - 1, 6, 10, 15-Tetraene

The complexes of Nicke l(II) and Copper(II) salts have been prepared with the macrocyclic ligand-1,7,10,16-tetraaza-8, 9, 17, 18-di benzo - 3,4,5,12,13,14-difuranylcyclooctadeca- 1, 6, 10, 15-tetraene. On the basis of characterization of compledxes formed with the macrocyclic ligand by usual physico-chemical methods such as elemental analysis, mea- surement of electrical conductance, magnetic moment and electronic tran- sition spectra of the complexes and I.R. spectral behaviour of both the ligand and the complexes. All the complexes of both the metals have been found to be non-electrolyte, mono-meric, paramagnetic with octahedral geometryy . The general molecular formula of the complexes have been found to be [M(L) (X)2] Where M= Nickel(II) and Copper(II) Cations, L= macrocyclic ligand and X= monodentate anion.

Competition between the Ni and Fe Redox in the O3-NaNi1/3Fe1/3Mn1/3O2 Cathode Material for Na-Ion Batteries

Sodium-ion batteries are attracting great attention due to their low cost and abundance of sodium. The O3-type NaNi1/3Fe1/3Mn1/3O2 layered oxide material is a promising candidate for positive electrodes (cathodes) in Na-ion batteries. However, its stable electrochemical performance is restricted by the upper voltage limit of 4.0 V (vs Na/Na+), which allows for reversibly removing 0.5–0.55 Na+ per formula unit, corresponding to the capacity of 120–130 mAh·g–1. Further reduction of sodium content inevitably accelerates capacity degradation, and this issue calls for a detailed study of the redox reactions that accompany the electrochemical (de)intercalation of a large amount of sodium. Here, we present operando and ex situ studies using powder X-ray diffraction and X-ray absorption spectroscopy combined with 57Fe Mössbauer spectroscopy. Our approach reveals the sequence of the redox transitions that occur during the charge and discharge of O3-NaNi1/3Fe1/3Mn1/3O2. Our data show that in addition to nickel and iron cations oxidizing to M+4, a part of iron transforms into the “3 + δ” state owing to the fast electron exchange Fe3+ + Fe4+ ↔ Fe4+ + Fe3+. This process freezes upon cooling the material to 35 K, producing Fe4+ cations, some of which occupy tetrahedral positions.

Preparation of some Complexes of Nickel(II) and Copper (II) Metals with Macrocyclic Ligand, 1,7,9,15 tetra-aza-3,5,11,13 difurano-cyclo-1,6,9,14-hexa-deca tetra ene

The complexes of Nickel(II) and Copper(II) metals have been prepared with the macrocyclic ligand-1,7,9, 15-tetra-aza-3, 5,11,13- - difurano-cyclo-1,6,9,14-hexa deca tetra-ene. The complexes of both the metals have been characterised by usual physico-chemical methods such as elemental analysis, measurement of electrical conductance, magnetic moment and electronic transition spectra of the complexes and I.R. spectral behaviour of both ligands and the complexes. All the complexes of both the metals have been found to be non-electrolyte, mono-meric, paramagnetic with octahedral geometryy . T he general molecular formula of the complexes have been found to be [M(L) (X)2] Where M= Nickel(II) and Copper(II) Cations, L= ligand and X= monodentate anions.

MOLECULAR DYNAMICS SIMULATION OF MOLTEN NiF&lt;sub&gt;2&lt;/sub&gt;: STRUCTURE AND TRANSPORT PROPERTIES

Computer modeling of molten nickel fluoride was carried out using classical molecular dynamics in the temperature range 1750–1900 K. The density of crystalline NiF2 with a relative error of less than 1% verified the parameters of the pair potential obtained in the framework of the quantum-chemical approximation. The calculated radial distribution functions and coordination numbers for the Ni–F pair indicate a distorted octahedral environment of the nickel cation in the melt. In this case, a slight decrease in the nearest cation-anion distance was found in comparison with solid nickel fluoride. It is shown that the curve of the radial distribution function for the fluorine-fluorine pair near the main peak splits into two maxima. The position of the first peak at 2.67 Å is characterized by a coordination number of 5.1 and describes neighboring anions in a distorted octahedron. Whereas, the second maximum can be associated with fluorine anions located along the F–Ni–F line with a peak position at 3.83 Å, which indicates a decrease in a similar distance compared to the crystal. The coefficients of self-diffusion of ions and the viscosity of the NiF2 melt at different temperatures were calculated.

Investigation of the mechanism of nickel hydroxide formation from nickel nitrate

Nickel hydroxides are widely used as electrochemically active substances in alkaline batteries and hybrid supercapacitors; they can be used for electrocatalysis, in electrochemical sensors, and as pigments. Knowledge of the formation mechanism of nickel hydroxides is necessary for developing and optimizing targeted synthesis methods. The thermal effects of processes in the formation of nickel hydroxide from nitrate were studied by the calorimetry method. The mechanism of precipitate formation was investigated by the method of simultaneous potentiometric (with a glass universal electrode) and conductometric titration. The nickel content in the samples obtained at the determined NaOH/Ni2+ ratios was investigated by the chemical method of trilonometry after preliminary dissolution. Calorimetric investigations showed that the reaction of nickel nitrate with NaOH was exothermic with ΔНreaction=‒28328.5 J/mol. The exothermic nature of the NaOH dilution process was revealed with ΔНdilution =‒2454 J/mol. According to the results of potentiometric titration, the formation of a basic salt of the NiOHNO3 type was not detected. Analysis of the results of conductometric titration revealed a two-stage chemical mechanism for the formation of nickel hydroxide from nitrate. At the first stage, which had a high rate, due to the liquid-phase reaction of the nickel cation with the hydroxyl anion, a primary precipitate of the composition Ni(OH)1.87(NO3)0.13 was formed. In the second stage, as a result of a slow topochemical reaction of the primary precipitate with hydroxyl anions, nitrate ions were displaced from the precipitate to form nickel hydroxide. These data are confirmed by the analysis of precipitate obtained at NaOH/Ni2+ ratios of 1.87 and 2.2: the Ni content was 52.95 % and 55.63 %, corresponding to the formulas Ni(OH)1.87(NO3)0.13∙0.68H2O and Ni(OH)2∙0.71H2O. This clearly indicated that the primary precipitate was nitrate-doped α-Ni(OH)2 and the final precipitate corresponded to the α-modification of nickel hydroxide

Improved Electrochemical Hydrogen Peroxide Detection Using a Nickel(II) Phthalimide-Substituted Porphyrazine Combined with Various Carbon Nanomaterials.

A metal-free porphyrazine derivative with peripheral phthalimide substituents was metallated with a nickel(II) ion. The purity of the nickel macrocycle was confirmed using HPLC, and characterized by MS, UV-VIS, and 1D (1H, 13C) and 2D (1H-13C HSQC, 1H-13C HMBC, 1H-1H COSY) NMR techniques. The novel porphyrazine was combined with various carbon nanomaterials, such as carbon nanotubes-single walled (SWCNTs) and multi-walled (MWCNTs), and electrochemically reduced graphene oxide (rGO), to create hybrid electroactive electrode materials. The carbon nanomaterials' effect on the electrocatalytic properties of nickel(II) cations was compared. As a result, an extensive electrochemical characterization of the synthesized metallated porphyrazine derivative on various carbon nanostructures was carried out using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). An electrode modified with carbon nanomaterials GC/MWCNTs, GC/SWCNTs, or GC/rGO, respectively, was shown to have a lower overpotential than a bare glassy carbon electrode (GC), allowing for the measurement of hydrogen peroxide in neutral conditions (pH 7.4). It was shown that among the tested carbon nanomaterials, the modified electrode GC/MWCNTs/Pz3 exhibited the best electrocatalytic properties in the direction of hydrogen peroxide oxidation/reduction. The prepared sensor was determined to enable a linear response to H2O2 in concentrations ranging between 20-1200 µM with the detection limit of 18.57 µM and sensitivity of 14.18 µA mM-1 cm-2. As a result of this research, the sensors produced here may find use in biomedical and environmental applications.

(R,R)-Tartrate as a polytopic ligand for UO22+: Mono- and diperiodic coordination polymers including di- and tetranuclear subunits

(R,R)-Tartaric acid (H4tart) has been reacted with uranyl nitrate hexahydrate under solvo-hydrothermal conditions, in the presence of either [Ni(R,S-Me6cyclam)]2+ (R,S-Me6cyclam = 7(R),14(S)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane), quinH+ (quinuclidinium), or [Ni(bipy)3]2+ (bipy = 2,2ʹ-bipyridine), to give three complexes characterized by their crystal structure. [H2NMe2]2[(UO2)2(Htart)2(HCOO)2Ni(R,S-Me6cyclam)]⋅2H2O (1) crystallizes as a monoperiodic coordination polymer in which dimeric [UO2(Htart)]22– subunits are linked by nickel(II) cations. The structure of the dimers matches that expected from solution experiments but not previously found in the solid state. Both [Hquin][(UO2)2(tart)(CH3COO)] (2) and [Ni(bipy)3][(UO2)2(tart)(CH3COO)]2 (3) crystallize as diperiodic networks based on tetranuclear [(UO2)2(tart)(CH3COO)]22– subunits which contain a central U2O2 ring involving μ2-bridging alkoxide groups. Further chelation of the two lateral uranyl cations by the carboxylate groups of adjacent subunits yields a sql-type network. Due to the different bulk of the counterions, the layers are quasi-planar in 2 and corrugated in 3. Comparison of these polynuclear subunits with those formed by the related ligands citrate, R,S-malate and R-citramalate shows that while the dimeric form is common to all, the tetranuclear subunit is specific to the tartrate ligand.

Photo- And Ionochromic Diarylethenes with Receptor Fragments in The Thiazole Bridge

Diarylethenes containing coumarin and thiophene substituents in the thiazole bridge and quinoline receptor fragments were synthesized. 2-Chloroquinoline diarylethenes form colored cyclic hexadiene forms under UV light, which undergo reverse isomerization when exposed to visible light. 2-Hydroxyquinoline diarylethenes are nonphotochromic. The ionochromic effects of interaction with fluoride anions and copper(II) and nickel(II) cations were studied.

Binding of His-tagged molecules to giant vesicles via anchor lipids.

Giant unilamellar vesicles (GUVs) are versatile biomimetic membrane compartments made of a lipid bilayer. For the biofunctionalization of the membranes, proteins can be attached peripherally to membranes using anchor lipids. One such anchor lipid is the 1,2-dioleoyl-sn-glycero-3-[(N-(5-amino-1-carboxypentyl) iminodiacetic acid) succinyl] (DGS-NTA) lipid, which has a head group that can bind to metal cations and subsequently to proteins via a six-histidine (6H) chain. The proteins are tagged with fluorescent molecules to visualize them in the confocal microscope. We use two molecules with a 6H tag - fluorescein isothiocyanate (FITC) and green fluorescent protein (GFP). The binding affinity of the protein to the NTA lipid is affected by the size of the molecule and the choice of the metal cation in the head group. In this study, we use a microfluidic device to expose the GUVs with NTA lipids to a constant His-tagged fluorophore concentration in the exterior solution. The equilibrium dissociation constant for the NTA chelated to divalent nickel cation (Ni2+) is measured to be 37.5 nM for 6H-GFP and 18.5 nM for 6H-FITC (Soft matter, 2022, 18, 6372). We also establish a DGS-NTA lipid system that chelates to trivalent cobalt cation (Co3+) and compare it to the Ni2+ system. We achieve such a system without oxidizing reagents, keeping the lipids and the protein unaffected.

Selective Dual-Ion Modulation in Solid-State Magnetoelectric Heterojunctions for In-Memory Encryption.

Nanoionic technologies are identified as a promising approach to modulating the physical properties of solid-state dielectrics, which have resulted in various emergent nanodevices, such as nanoionic resistive switching devices and magnetoionic devices for memory and computing applications. Previous studies are limited to single-type ion manipulation, and the investigation of multiple-type ion modulation on the coupled magnetoelectric effects, for developing information devices with multiple integrated functionalities, remains elusive. Here, a dual-ion solid-state magnetoelectric heterojunction based on Pt/HfO2- x /NiOy /Ni with reconfigurable magnetoresistance (MR) characteristics is reported for in-memory encryption. It is shown that the oxygen anions and nickel cations can be selectively driven by voltages with controlled polarity and intensity, which concurrently change the overall electrical resistance and the interfacial magnetic coupling, thus significantly modulate the MR symmetry. Based on this device, a magnetoelectric memory prototype array with in-memory encryption functionality is designed for the secure storage of image and digit information. Along with the advantages including simple structure, multistate encryption, good reversibility, and nonvolatile modulation capability, this proof-of-concept device opens new avenues toward next-generation compact electronics with integrated information functionalities.

Synthesis, crystal structure and thermal properties of tetra-kis-(3-methyl-pyridine-κN)bis-(thio-cyanato-κN)nickel(II).

Reaction of Ni(NCS)2 with 3-methyl-pyridine in water leads to the formation of crystals of the title compound, [Ni(NCS)2(C6H7N)4]. All of them are of poor quality and non-merohedrally twinned but a refinement using data in HKLF-5 format leads to a reasonable structure model and reliability factors. The crystal structure of the title compound consists of discrete complexes, in which the nickel cations are sixfold coordinated by two terminal N-bonded thio-cyanate anions and four 3-methyl-pyridine ligands within slightly distorted octa-hedra. One of the 3-methyl-pyridine ligands is disordered and was refined using a split model. The discrete complexes are arranged into layers. X-ray powder diffraction proves that pure samples have been obtained, and in the IR spectrum, the CN stretching vibration is observed at 2072 cm-1, in agreement with the presence of only terminally coordinated thio-cyanate anions. Comparing the calculated powder pattern with those of the residues obtained by solvent removal from several solvates already reported in the literature proves that, in each case, this crystalline phase is formed. Assessing the crystal structures of the solvates in comparison with that of the ansolvate reveals some similarities.

Диагностика вредных примесей в водных средах с помощью спектроскопических методов и алгоритмов машинного обучения

The results of the development of a method for diagnosing 8-component aqueous solutions containing lithium, ammonium, iron (III), nickel, copper and zinc cations, as well as sulfate and nitrate anions, by IR absorption spectra and optical density spectra using artificial neural networks are presented. The application of artificial neural networks to the obtained arrays of spectroscopic data made it possible to ensure the simultaneous determination of the studied ions in a multicomponent mixture with an accuracy that satisfies the needs of environmental monitoring of natural and waste waters, as well as diagnostics of technological environments.