Nickel

The current investigation proposes a novel method for simultaneous assessment of the electrochemical and structural fatigue properties of nickel-titanium shape memory alloy (NiTi SMA) wires. The design and layout of an in situ electrochemical cell in a custom-made bending rotation fatigue (BRF) test rig is presented. This newly designed test rig allows performing a wide spectrum of experiments for studying the influence of fatigue on corrosion and vice versa. This can be achieved by performing ex situ and∕or in situ measurements. The versatility of the combined electrochemical∕mechanical test rig is demonstrated by studying the electrochemical behavior of NiTi SMA wires in 0.9% NaCl electrolyte under load. The ex situ measurements allow addressing various issues, for example, the influence of pre-fatigue on the localized corrosion resistance, or the influence of hydrogen on fatigue life. Ex situ experiments showed that a pre-fatigued wire is more susceptible to localized corrosion. The synergetic effect can be concluded from the polarization studies and specifically from an in situ study of the open circuit potential (OCP) transients, which sensitively react to the elementary repassivation events related to the local failure of the oxide layer. It can also be used as an indicator for identifying the onset of the fatigue failure.

Nickel ingested with food can elicit either systemic cutaneous or gastrointestinal symptoms causing a systemic nickel allergy syndrome (SNAS) that can be treated with tolerance by oral ingestion of the metal. It has been suggested that interleukins 2 (IL-2) and 10 (IL-10) are involved in the mechanisms underlying oral tolerance. We evaluated the clinical efficacy of oral desensitization therapy in SNAS consisting in the administration of nickel sulphate. Because nickel allergy prevalently affects women, only female subjects (N = 22) were recruited. Oral nickel desensitizing therapy was associated with low-nickel diet for three months. Before and after therapy, clinical conditions were evaluated, and circulating cytokines IL-2 and IL-10 were measured. After the two-year treatment, visual analogue scale (VAS) scores for symptoms were significantly reduced (P less than 0.001). Patients were released by either cutaneous or gastrointestinal symptoms and by tolerating nickel-containing fo...

A series of plasmid vectors, pRSET A, B, and C, have been developed for high-level protein expression in prokaryotes and have been characterized. Based upon the T7 RNA polymerase-driven pET system, the pRSET vectors encode recombinant proteins as fusions with a multifunctional leader peptide containing a hexahistidyl sequence for purification on Ni(2+)-affinity resins, a tyrosine residue for radioiodination, and an enterokinase proteolytic cleavage site for leader peptide removal. Monoclonal antibodies (MAbs) to two epitopes on the leader peptide, which also contains amino acids 1-12 of the T7 gene 10 major capsid protein, were developed and provide for universal immunological detection of pRSET-expressed fusion proteins. Subcloning of protein-encoding DNA is facilitated by an 11-site polylinker which is offset for all three ribosomal reading frames, and an f1(+) origin of DNA replication permits single-stranded DNA synthesis for site-directed mutagenesis protocols. Representative fusion proteins overexpressed in Escherichia coli were successfully purified under both denaturing and nondenaturing conditions by single-step Ni2+ affinity chromatography. Purification was independent of recombinant protein solubility in sonicated or freeze-thawed E. coli lysates. Isolation of MAbs for selective recognition of either of two leader peptide epitopes was demonstrated by immunoprecipitation, but this selectivity was less evident under conditions for Western blotting. In combining the utility of T7 RNA polymerase-directed expression with several recent advances in protein purification and detection, the pRSET vectors will serve as a powerful resource for a variety of studies in protein biochemistry.

... The spectra are quite similar to that obtained in Nujol mull, This strongly indicates that in the non.aqueous solveuts the pendanl acetic acid group of I Cu(HL') 1" ' is not deproton+ ated and is coordinated to the metal ion, likewise in the solid state, In the spectra of I CuL" ] + in the ...

Metallic allergens such as nickel are among the most common causes of allergic contact dermatitis (ACD), but frequencies of contact dermatitis to these allergens may vary in different areas. This study aimed to determine the frequencies of ACD caused by three common metallic allergens: nickel sulfate; potassium dichromate; and cobalt chloride. Data for 1137 patients with clinical diagnoses of contact dermatitis and/or atopic dermatitis evaluated by patch testing in Iran during a 5-year period were retrospectively studied to establish the frequencies of hypersensitivity to these metallic allergens. A total of 313 patients (27.5%) gave positive patch test results for at least one metallic allergen. Allergy to nickel (229 cases, 20.0%) was the most commonly observed, followed by allergy to cobalt (90 cases, 8.0%) and allergy to chromium (70 cases, 6.2%). Nickel allergy was significantly more frequent in females and in subjects aged <40 years, whereas chromium hypersensitivity was more common in males and in subjects aged >40 years. Sensitivity to nickel or chromium was a risk factor for cobalt allergy. Nickel was most commonly identified as a metallic allergen in Iran and tended to affect women aged <40 years. Regulations pertaining to nickel release may decrease the frequency of nickel hypersensitivity in Iran.

The frequency of sensitization to contact allergens varies in different countries because of both genetic and, more importantly, allergen exposure variations. The objective is to determine the frequency of sensitization to contact allergens in Iranian patients with dermatitis. 250 patients with a clinical diagnosis of contact dermatitis and/or atopic dermatitis were evaluated with a 28-allergen screening series recommended by the German Contact Dermatitis Research Group from September 2002 to April 2004 in Tehran, Iran. The patches were applied on the back of the patients, removed after 24 hr and the readings were taken on 24 hr, 48 hr and 72 hr after application. 126 patients (50.4%) showed at least 1 positive reaction, and 23 patients (9.2%) had more than 2 positive reactions. 189 (84.4%) of 224 positive reactions had past and/or present clinical relevance. The 5 most common allergens were nickel sulfate 70 (28.0%), cobalt chloride 32 (12.8%), para-tertiarybutyl phenol formaldehyde resin 20 (8.0%), potassium dichromate 13 (5.2%) and colophony 13 (5.2%). Contact allergy to nickel sulfate was significantly more common in female patients and in patients under 40 years of age (P < 0.05). Nickel sulfate is the most common contact allergen in Iran, mostly affecting women and younger patients probably because of more exposure.

This study investigated the acute toxicity of nickel (Ni) to cardinal tetra (Paracheirodon axelrodi), within the three main water types of the Amazon basin: black (Rio Negro), white (Rio Solimões) and clear (Rio Tapajós) during the wet and dry season at pH 7 (representative of white and clear rivers) and pH 4 (representative of black waters). The influence of dissolved organic carbon (DOC) quality on Ni toxicity within the three waters was also explored via the use of DOC isolates. Differences in water chemistry, DOC quality and ion concentrations were shown between waters and between seasons. Toxicity of Ni was shown to vary between river waters, seasons, and pHs. Ni was significantly less toxic during the dry season at pH 4 in all three river waters; for example, black water during the wet season had an LC50 of 9.72 mg Ni/L compared to 41.5 mg Ni/L during the dry season. At pH 7, contrasting effects in toxicity between seasons were shown between black and clear waters (black: wet ...

We demonstrate a 2.5-fold coercivity reduction in FePt based exchange coupled composite bit patterned media (ECC-BPM) by coupling a lower anisotropy Co/Pd-Co/Ni-multilayer system to the top of a high anisotropy FePt L10 film. Furthermore the tight switching field distribution (SFD) of the lower anisotropy system reduces the SFD of the ECC-BPM composite system compared to a single layer FePt film.

Nitinol alloys are rapidly being utilized as the material of choice in a variety of applications in the medical industry. It has been used for self-expanding stents, graft support systems, and various other devices for minimally invasive interventional and endoscopic procedures. However, the biocompatibility of this alloy remains a concern to many practitioners in the industry due to nickel sensitivity

A new Ni(II) optical chemical sensor (optode) based on immobilizing of 2-amino-1-cyclopentene -1-dithiocarboxylic acid (ACDA) to transparent acetyl cellulose film was developed. The sensor was fabricated by binding ACDA to a cellulose acetate film that had previously been ...

A novel ionic liquid modified NiO/CNTs carbon paste electrode (IL/NiO/CNTCPE) had been fabricated by using hydrophilic ionic liquid 1-methyl-3-butylimidazolium chloride [MBIDZ]Cl as a binder. The cyclic voltammogram showed an irreversible oxidation peak at 0.61 V (vs. Ag/AgCl(sat)), which corresponded to the oxidation of morphine. Compared to common carbon paste electrode, the electrochemical response was greatly improved for morphine electrooxidation. This modified electrode exhibited a potent and persistent electron mediating behavior followed by well separated oxidation peaks of morphine and diclofenac. Detection limit of morphine was found to be 0.01 μM using square wave voltammetry (SWV) method. The proposed sensor was successfully applied for the determination of morphine in human urine and pharmaceutical samples.

Introduced approximately two decades ago, macrocyclic deprotonated tetraamido (4N) and, nearly a decade earlier, acyclic diamidodialkoxido or diamidophenolato (2N/2O) ligand systems have been used, among other things, for the synthesis of a wide variety of high-valent ...

In this work, spinel based zinc, nickel and zinc-nickel ferrites were synthesized and modified with oxidatively polymerized polyaniline-phosphate. The corrosion protection behavior of these polymer modified ferrites was investigated after formulating with acrylic primer and subsequent coating on carbon steel panels. Salt spray test revealed that among all the anticorrosion pigments, polyaniline modified zinc-nickel ferrites showed significantly improved anticorrosion properties.

Page 1. 6342 J. Am. Chem. SOC. 1991, 113, 6342-6343 Coupled CH Bond Heterolysis and Tautomerism in a Nickel Macrocyclic Complex with a Thiolate Ligand Jonathan J. Wilker, Andrew Gelasco, Michelle A. Pressler, Roberta 0. Day, and Michael J. Maroney* ...