The influence of iron content on the biofouling resistance of 90/10 copper‐nickel alloys

A series of 90/10 cupronickel alloys containing iron at levels between 0% and 5% were immersed in the sea in Chichester Harbour. Samples were retrieved over a 14‐month period and subjected to scanning electron microscopy, energy dispersive X‐ray analysis and X‐ray photoelectron spectroscopy. The alloy with no iron corroded very rapidly and showed little, if any, colonisation. The 0·5% Fe and 1·5% Fe alloys developed microfouling communities dominated by the diatom Amphora, while the 2·5% and 5% Fe‐containing materials showed not only diatoms but also macro‐fouling in the form of barnacle settlement. However, the very loosely adherent nature of the iron and nickel‐rich corrosion products of these high iron alloys resulted in very poor tenacity of adhesion by the macrofouling. However, thick films of diatoms of lower copper tolerance became well established on the iron‐rich alloys. The alternative anti‐fouling mechanisms of the 90/10 copper‐nickels are discussed.     

Molecular dissection of the role of histidine in nickel hyperaccumulation in Thlaspi goesingense (Hálácsy)

To understand the role of free histidine (His) in Ni hyperaccumulation in Thlaspi goesingense, we investigated the regulation of His biosynthesis at both the molecular and biochemical levels. Three T. goesingense cDNAs encoding the following His biosynthetic enzymes, ATP phosphoribosyltransferase (THG1, GenBank accession no. AF003347), imidazoleglycerol phosphate dehydratase (THB1, GenBank accession no. AF023140), and histidinol dehydrogenase (THD1, GenBank accession no. AF023141) were isolated by functional complementation of Escherichia coli His auxotrophs. Northern analysis of THG1, THD1, and THB1 gene expression revealed that each gene is expressed in both roots and shoots, but at the concentrations and dosage times of Ni treatment used in this study, these genes failed to show any regulation by Ni. We were also unable to observe any increases in the concentration of free His in root, shoot, or xylem sap of T. goesingense in response to Ni exposure. X-ray absorption spectroscopy of root and shoot tissue from T. goesingense and the non-accumulator species Thlaspi arvense revealed no major differences in the coordination of Ni by His in these tissues. We therefore conclude that the Ni hyperaccumulation phenotype in T. goesingense is not determined by the overproduction of His in response to Ni.     

Do high-nickel leaves shed by the nickel hyperaccumulator Alyssum murale inhibit seed germination of competing plants?

Elemental allelopathy suggests that nickel (Ni)-rich leaves shed by hyperaccumulators inhibit the germination and growth of nearby plant species. Here, the germination of eight herbaceous species following addition of Alyssum murale biomass or Ni(NO3)2, with the same Ni level added to soil, was assessed. The distribution of Ni in soil was tested by determining Ni phytoavailability and speciation over time. Phytoavailable Ni in soil amended with biomass declined rapidly over time due to Ni binding to iron (Fe)/manganese (Mn) oxides in the soil. No significant effects on seed germination were observed. Unlike the Ni complex in Alyssum biomass, more Ni remained soluble and phytoavailable in soil amended with Ni(NO3)2, thus significantly inhibiting seed germination. High-Ni leaves shed by hyperaccumulators did not appear to create a 'toxic zone' around the plants and inhibit germination or growth of competing plants. The lack of an allelopathic effect was probably related to low Ni availability.     

Synthesis and electrochemical studies of octahedral nickel β-diketonate complexes

The reaction of [Ni(tmhd)₂] and [Ni(dbm)₂] with N-donor chelating ligands in dichloromethane and acetone, respectively, yields the complexes [Ni(tmhd)₂(L-L)] (L-L = 2,2′-bpy 1, phen 2 and dmae 3) and [Ni(dbm)₂(L-L)] (L-L = 2,2′-bpy 4, phen 5, dmae 6). UV-Vis spectroscopy shows very strong bands in the UV region consistent with ligand centred π → π^∗ transitions. The electrochemical studies of 1-6 reveal oxidation to Ni(III). The [Ni(tmhd)₂(L-L)] 1-3 are more easily oxidized by ca. 300 mV and are quasi-reversible whereas for the [Ni(dbm)₂(L-L)] series only complex 6 shows significant reversibility. X-ray crystallographic studies have been conducted in the case of [Ni(dbm)₂(phen)] 5 and [Ni(dbm)₂(dmae)] 6. The structures both show that the nickel metal centre is octahedral with an O₄N₂ coordination environment. In the structures the β-diketonate ligands exhibit a cis-arrangement, with the metal displaced out of the planar chelate ring.     

Stabilization of monovalent nickel in aqueous solutions by complexation with the β-isomer of C-5,12-racemic-1,4,5,7,7,8,11,12,14,14-decamethyl-1,4,8,11-tetraazacyclotetradecane

The monovalent nickel complex formed by the reduction of the β-isomer of the complex of C-5,12- racemic-1,4,5,7,7,8,11,12,14,14-decamethyl-1,4,8,11- tetraazacyclotetradecane nickel(II), NiL₁²⁺ in 0.1 M HCO₂Na, pH 7.6, has a half-life longer than 90 h. The redox potential of the couple NiL₁⁺/NiL₁²⁺ is −0.94 V vs. Ag/AgCl. The absorption spectrum of NiL₁⁺ consists of a band with λ_max = 335 nm and ϵ_max = 2200 M⁻¹ cm⁻¹. For the analogous complex with C-5,12-racemic-5,7,7,12,14,14-hexamethyl-1,4, 8,11-tetraazacyclotetradecane, L₂, the half-life time of NIL₂⁺ is less than 1 min and the redox potential is −1.44 V vs. Ag/AgCl. These results are similar to those reported earlier for the analogous nickel complexes with the meso-isomers of the ligands. The results thus indicate that both the kinetic and thermodynamic stabilization of monovalent nickel by N-methylation of tetraazamacrocyclic ligands is not significantly affected by the configuration of the ligand.     

Characteristics of a nickel–albumin binding assay for assessment of myocardial ischaemia

Background: The aim of this study was to describe a method to measure ischaemia-induced alterations of the binding capacity of serum albumin to exogenous nickel.

Methods: We measured the levels of cardiac troponin I (cTnI), serum albumin, ischaemia-modified albumin (IMA) measured by a cobalt–albumin binding assay (CABA), and a nickel–albumin binding assay (NABA) in the following groups: myocardial infarction (n?=?32) and non-ischaemic chest pain (n?=?64).

Results: IMA, cTnI and NABA levels were higher in the myocardial infarction group. NABA presented a higher ability to discriminate myocardial ischaemia than CABA.

Conclusions: Patients with myocardial infarction have reduced nickel binding to human serum albumin, and NABA may have an important role as an early marker of myocardial ischaemia.     

Finite element modeling of superelastic nickel–titanium orthodontic wires

Thanks to its good corrosion resistance and biocompatibility, superelastic Ni–Ti wire alloys have been successfully used in orthodontic treatment. Therefore, it is important to quantify and evaluate the level of orthodontic force applied to the bracket and teeth in order to achieve tooth movement. In this study, three dimensional finite element models with a Gibbs-potential-based-formulation and thermodynamic principles were used. The aim was to evaluate the influence of possible intraoral temperature differences on the forces exerted by NiTi orthodontic arch wires with different cross sectional shapes and sizes. The prediction made by this phenomenological model, for superelastic tensile and bending tests, shows good agreement with the experimental data. A bending test is simulated to study the force variation of an orthodontic NiTi arch wire when it loaded up to the deflection of 3 mm, for this task one half of the arch wire and the 3 adjacent brackets were modeled. The results showed that the stress required for the martensite transformation increases with the increase of cross-sectional dimensions and temperature. Associated with this increase in stress, the plateau of this transformation becomes steeper. In addition, the area of the mechanical hysteresis, measured as the difference between the forces of the upper and lower plateau, increases.     

A DFT overview of high-valent iron, cobalt and nickel tetraamidomacrocyclic ligand (TAML) complexes: the end of innocence?

Amidato-N ligands are normally viewed as classic, strongly sigma-donating, innocent ligands. However, when coordinated to high-valent transition metal centers, tetraamidomacrocyclic ligands are often substantially non-innocent, i.e., exhibit radical character involving the amido pi-systems. Even the so-called MAC* ligand, generally considered to be an innocent ligand, is non-innocent in several of its known complexes.     

Physical parameter-based allocation for the energy consumption of pyro-metallurgical system—a case study on nickel production in China

Purpose

The objectives of this study were to establish an allocation model for the energy consumption of pyro-metallurgical system based on the physical relationship between the input and output, apply the established model to nickel production in China and compare the difference between the allocation results derived from the established model and the traditional models.

Methods

The basic methodological idea of this study is that the energy input of a multi-output pyro-metallurgical process should be allocated according to how the energy input is consumed in the process. The energy consumption of pyro-metallurgical system was decomposed into different categories (e.g. energy absorption of chemical reaction and energy loss), and these categories were classified into two groups, i.e. the categories of energy consumption dependent on the product ratio (PRDE) and the categories of energy consumption independent on the product ratio (PRIE); then, the allocation basis for each category of energy consumption was determined through the physical relationship between the energy input and metal output. The allocation for the energy consumption of nickel production in China was carried out; the system boundary includes two sub-systems (i.e. Ni–Cu coproduction system and Ni refining system), and the energy consumption of the coproduction system should be allocated; the basic data required by the allocation model and the compilation of LCI were mainly obtained from literature.

Results and discussion

The energy consumption of the processes of mining, drying, converting and floating-grinding belongs to PRIE following the principle of mass-based allocation, and the corresponding allocation factors are 64, 64, 69 and 69 %, respectively. The categories of energy consumption involved in the smelting process (the key process for demonstrating the allocation model) include both PRIE and PRDE, and the aggregated allocation factor was calculated as 56 %. The allocation result derived from the established model is lower than the results derived from the mass-based model and the market value-based model, because that, through the desulphurization reactions that occurred in the smelting process, the chemical states of copper and nickel are transformed from copper pyrite (CuFeS₂) and nicopyrite ((Fe,Ni)₉S₈) into cuprous sulphide (Cu₂S) and nickel sulphide (Ni₃S₂), and copper compound releases more sulphur atoms than nickel compound. When analyzing a single pyro-metallurgical process, the result of allocation is sensitive to basis selection; however, when comparing two or more pyro-metallurgical processes, the comparison result of allocation is relatively insensitive to basis selection.

Conclusions

The energy input of pyro-metallurgical system is consumed in different physical-chemical ways; the decomposition of energy consumption is significant for choosing allocation bases; the basis of mass can only be used for the allocation of PRIE, and choosing the same allocation basis for different cases without a systematic analysis will be inappropriate. The requirement of some nontraditional extra inventory data is the major limitation of the established model. This study mainly focused on how nickel production system consumes the energy input, and the energy consumption patterns of other production systems should be taken into account in future studies.

     

Synthesis of mixed sphere β-diketonate nickel(II) complexes

Complexes of the type [Ni(β-diketonate)(L L)_1,2] (LL = diphosphine, (2), en or dipy, (3)) have been synthesized from [Ni(β-diketonate)₂] (1) and the free ligand under stoichiometric conditions in ethanol. Complexes 2 are square-planar species, while compounds 3 are hexacoordinate complexes, all being quite stable toward ligand disproportionation. The ligand-set {P₂O₂^-} appears to be particularly stable in the nickel(II) coordination sphere and turns out to exert a fairly strong average ligand field.     

Does the lichen mat alleviate the effects of wet deposited nickel on soil microorganisms and Scots pine (Pinus sylvestris L.) seedlings?

A field experiment was conducted in a dry heath forest dominated by Scots pine (Pinus sylvestris L.) and a mat-forming lichen (Cladina stellaris (Opiz) Brodo) to assess the effect of wet-deposited nickel (Ni) on pine seedlings and soil microorganisms, and to explore whether an intact lichen mat could act as a buffer against heavy metal deposits. Pine seedlings were planted in quadrats covered by a natural lichen layer and in quadrats from which the lichen layer had been completely removed. The quadrats were exposed to four levels of Ni deposition: 0 (i.e., distilled water), 10, 100 and 1000 mg m^–2 year^–1 in two growing seasons. Increasing Ni deposition led to an increase in the Ni content of the needles, roots and the soil organic layer. The lichen mat reduced Ni flow to the organic soil layer, but had no significant, reducing effect on needle or root Ni concentration. The most severe Ni treatment had detrimental effects on seedling growth and increased peroxidase activity in the previous years needles. Removal of the lichen layer did not increase susceptibility of seedlings to Ni. Values of maximal carbon use efficiency (Max) and metabolic quotient (qCO₂) of the soil microorganisms indicated protective value of the lichen mat to soil microorganisms at the highest Ni treatment. Skimming per se decreased basal respiration, qCO₂ and concentrations of potassium in the soil and also increased the lag period of the microorganisms as a response to in situ substrate addition.     

Effect of cortisone on the developmental pattern of the neutral and the acid β-galactosidases of the small intestine of the rat

1. The developmental pattern and effect of cortisone on acid beta-galactosidase and neutral beta-galactosidase were studied in postnatal rats by a recently proposed method for their independent determination. 2. After birth the acid beta-galactosidase activity increases in the ileum, whereas it decreases slightly in the jejunum. On day 16 after birth the activity in the ileum decreases and in 20-day-old rats activity in both parts of the intestine decreases to adult values. In suckling animals the activity in the ileum exceeds the jejunal activity severalfold and in adult animals the activity in the jejunum is slightly higher than that in the ileum. 3. Neutral beta-galactosidase activity is high after birth and decreases in both jejunum and ileum after day 20 after birth. In 12-20-day-old rats activity in both parts is essentially the same, but in adult animals jejunal activity exceeds ileal activity four-to five-fold. 4. Cortisone (0.5, 2.0 or 5.0mg/100g body wt. daily for 4 days) does not influence the activity of either enzyme in 60-day-old rats. Acid beta-galactosidase activity is decreased after cortisone treatment in 8-, 12-, 16-and 18-day-old rats, with sensitivity to cortisone increasing with the approach of weaning. No effect of cortisone on acid beta-galactosidase is seen in 8-day-old rats. Neutral beta-galactosidase activity is increased in the ileum of 8-, 12-, 16- and 18-day old rats, but only in the jejunum of 8-and 12-day-old rats.     

Structural diversity of neutral bis-(β-iminoaldehyde) complexes of nickel(II)

Series of Ni^II and Cu^II complexes with dianionic [N₂O₂] ligands were synthesized and characterised applying spectroscopic and X-ray diffraction techniques. The ligands were obtained by 1:2 condensation of ethylene- and propylenediamine with malonic aldehyde derivatives (R² = H, R¹ = H or OCH₃). Although the molecular formulae of the complexes are quite similar, the X-ray investigations have proved a significant structural diversity in the solid state. Among others, we found some simple nearly planar molecules stacked in the crystal lattice with electron density of six-membered rings delocalised over the chelate rings as well as some very complex polymeric or nickel acetate bridged trinuclear complexes. The coordination of the nickel ion by surrounding oxygen and nitrogen atoms is square-planar in the simplest case and octahedral in the most complex one. Small topological differences in similar molecules generate completely different crystal structures.From magnetic studies, a small, negative value of J obtained confirms the occurrence of weak antiferromagnetic interactions between the Ni^II ions in polymeric chain of the propylenediamine dialdehyde substituted derivative.     

Spectroscopic investigation of nickel cation binding with adenine mononucleotides: stability and structure of the 1:2 complex with adenosine 5′-monophosphate

 The interaction of Ni(II) ions with adenine mononucleotides (5′-AMP, 3′-AMP, 2′-AMP, 2′,3′-cAMP, 3′,5′-cAMP) was studied in aqueous solution using Raman spectroscopy and ¹³C and ³¹P NMR paramagnetic relaxation measurements. Macrochelate structures were observed to form for all non-cyclic AMPs, with increasing stability in the series: 3′-AMP < 2′-AMP < 5′-AMP. N7 of adenine was found to be the key site of the Ni(II)-adenine interaction for all non-cyclic AMPs. For 2′-AMP, an alternative binding to the pyrimidine ring may also exist. The dependence of Raman spectra on AMP and Ni(II) concentration confirmed the existence of a stable 1 : 2 Ni(II)-(5′-AMP) complex, besides the 1 : 1 complexes. In this complex, the adenine moieties of both 5′-AMP molecules are situated close to Ni(II), and their relative orientations with respect to the cation are very similar. The paramagnetic relaxation enhancements of the carbons indicate that the nickel ion is not located in the plane of the adenine units, but that the line connecting Ni(II) and N7 deviates strongly from the adenine planes. Phosphates are outer-sphere coordinated by the cation. Findings from both methods have led us to propose possible global architectures of the complex. Received: 26 June 1998 / Accepted: 22 July 1998     

Association of the subunits of the calcium-independent receptor of α-latrotoxin

CIRL-1 also called latrophilin 1 or CL belongs to the family of adhesion G protein-coupled receptors (GPCRs). As all members of adhesion GPSR family CIRL-1 consists of two heterologous subunits, extracellular hydrophilic p120 and heptahelical membrane protein p85. Both CIRL-1 subunits are encoded by one gene but as a result of intracellular proteolysis of precursor, mature receptor has two-subunit structure. It was also shown that a minor portion of the CIRL-1 receptor complexes dissociates, producing the soluble receptor ectodomain, and this dissociation is due to the second cleavage at the site between the site of primary proteolysis and the first transmembrane domain. Recently model of independent localization p120 and p85 on the cell surface was proposed. In this article we evaluated the amount of p120-p85 complex still presented on the cellular membrane and confirmed that on cell surface major amount of mature CIRL-1 presented as a p120-p85 subunit complex.