Gallium ions

Imaging SIMS. Steeds et al. (1999) included this technique in their study of the distribution of boron introduced into diamond, where it is a well-established dopant that controls the electrical conductivity. SIMS was performed with a field-emission liquid gallium ion source interfaced to a magnetic sector mass spectrometer capable of about 0.1 pm spatial resolution. 

Gallium hydroxide is amphoteric, and is a much stronger acid than aluminum hydroxide. For Ga(OH)3 the first acid dissociation constant is 1.4 x 10-7 [for Al(OH)3 the value is 2 x 10-11].1 Polymerization occurs in aqueous Ga3+ solutions to which OH- is added,533 but this tendency is less than in the case of aluminum solutions (Section 25.1.5.1). The formation constants of mononuclear hydroxo complexes of Ga, including Ga(OH)4, and the hydrolysis constants of gallium ions have been measured by a competing ligand technique.534... 

Since ionic radii and valences of iron and chromium ions are similar to gallium ion, substitution of these cations with gallium ion may result in powders with similar crystal structure and properties to LSGM. Moreover, LaFe03- and LaCr03-based oxides are candidate cathode and anode materials for SOFC, respectively. 

Metallic gallium and its salts have little or no toxicity, compared to the very toxic thallium salts. The toxicity of the aluminum ion is controversial. The gallium ion has been investigated as a possible antitumor agent, but no clinically useful compounds have been produced, see also Inorganic Chemistry Mendeleev, Dimitri Semiconductors. 

One such approach has recently been developed and shown to enable high-resolution NSOM fluorescence and force measurements on viable cultured human arterial smooth muscle (HASM) cells under buffered conditions [28,29], This approach takes advantage of the nanofabrication capabilities of focused ion beam (FIB) milling to sculpt a light delivery structure into the end of a conventional AFM probe. The FIB technique, which utilizes a focused beam of gallium ions to mill samples with nanometer resolution, was first used by van Hulst and co-workers to modify conventional NSOM probes [30]. They demonstrated an improvement in single molecule fluorescence measurements using... 

The alumino and gallophosphates were formed [7] in the systems amine-Al(Ga)203—P205—H20 using the same way of the synthesis and the same range of temperatures and pressure. However, the introduction of phosphoric acid in the synthesis lowered the pH of the solutions to a neutral or weakly acidic medium which favours higher coordinations for aluminium and gallium ions. The combined effect of pH and of the shape of the amines lead to ca two hundred structure types. 

Nazarenko, V. A., and Nevskaya, E. M. Chemistry of the reactions between the ions of multivalent elements and organic reagents. XVII. Interaction of aluminum and gallium ions with methylthymol blue. J. Anal Chim. USSR 24(6), 670-673 (1969). 

In this work, a fusion protein has been engineered from maltose binding protein (pmal) and human metallothionein (MT). The fusion protein (pmal-MT) has been expressed in E. coli, and purified with an amylose column. The purified fusion protein was immobilized on a solid matrix, and its characteristics as metal binding ligand have been studied. We have found that the pmal-MT ligand efficiently binds gallium ion, one of the valuable rare metals desired to be recovered from aqueous solution [3]. Different binding mechanisms for two metal ions have been elucidated based on HSAB (hard and soft acids and bases) theory [4]. 

We have found that metallothionein, which selectively binds cadmium ion in vivo, binds gallium ion. The number of the gallium ion bound to one molecule of metallothionein, 26.6, was about twice as large as that of cadmium ion. The results of adsorption experiments to BSA, and the adsorption of various metal ions show that metallothionein selectively binds gallium ion. The specificity is very high because other metals which as similar ionic radius did not bound to the metallothinein as shown in Table 1. 

As elucidated from the adsorption experiment on BSA, adsorption of gallium ion by simple ion-exchange effect is negligible. The characteristics of metal ions such as ionic radius and hardness/softness, and the conformation of the metallothionein probably affect the selectivity of metal adsorption. The understanding of the mutual interactions among those factors would be a key dictor in designing the protein-based ligand suitable for a specific metal ion. 

Terashima, M., Oka, N., Sei, T. and Yoshida, H., Adsorption of cadmium ion and gallium ion to immobilized metallothionein fusion protein, Biotechnol. Progress, in press (2002)... 

Properties of doped oxides are summarized in Table X. The fraction of added lithium ions which is not extracted from the dehydrated solid by boiling water is considered as dissolved into the lattice of nickel oxide (80). It appears that the maximum solubility of lithium in nickel oxide is 2 at. % Li in these experiments (Table X). Because of the low temperature of firing (250°), lithium ions are most probably located in the surface layers of the oxide lattice. The amount of dissolved gallium ions is not known. 

Surface areas of pure or doped nickel oxides are not very different (Table X). It seems, however, that incorporation of lithium increases slightly the surface area of the solid and that incorporation of gallium ions has the opposite effect. 

Removal of lattice oxygen from the surface of nickel oxide in vcumo at 250° or incorporation of gallium ions at the same temperature [Eq. (14)] causes the reduction of surface nickel ions into metal atoms. Nucleation of nickel crystallites leaves cationic vacancies in the surface layer of the oxide lattice. The existence of these metal crystallites was demonstrated by magnetic susceptibility measurements (33). Cationic vacancies should thus exist on the surface of all samples prepared in vacuo at 250°. However, since incorporation of lithium ions at 250° creates anionic vacancies, the probability of formation of vacancy pairs (anion and cation) increases and consequently, the number of free cationic vacancies should be low on the surface of lithiated nickel oxides. Carbon monoxide is liable to be adsorbed at room temperature on cationic vacancies and the differences in the chemisorption of this gas are related to the different number of isolated cationic vacancies on the surface of the different samples. 

The competing ligand system alizarin-3-sulphonic acid-OH" has been used to determine formation constants of mononuclear hydroxo-complexes of Ga at 25 °C, and the hydrolysis constants of gallium ions at I = 0.1—l.O.519... 

A voltaic cell containing a standard Fe /Fe electrode and a standard Ga /Ga electrode is constructed, and the circuit is closed. Without consulting the table of standard reduction potentials, diagram and completely describe the cell from the following experimental observations, (i) The mass of the gallium electrode decreases, and the gallium ion concentration increases around that elec-... 

IR measurements on doped Si and shown that the subsurface mobile carriers can be probed by their response to an IR near-field with a spatial resolution of 30nm [48]. The group of Havenith presented a scanning near-field infrared microscopy (SNIM) system this is an IR s-SNOM set-up based on a continuous-wave optical parametric oscillator (OPO) as an excitation source with a much wider tunability compared to the usually applied CO2 lasers [49]. With this set-up, a subsurface pattern of implanted gallium ions in a topographically fiat silicon wafer was imaged with a lateral resolution of <30 nm. 

Gallium ions form coloured complexes with a number of triphenylmethane chelating reagents besides Eriochrome Cyanine R. Pyrocatechol Violet (PV) gives with Ga and diphenylguanidine a ternary complex, extractable into n-butanol-CHCh (1-fl) mixture (e=1.08-10 ) [32]. In another extractive spectrophotometric method with PV,... 

Kazansky V B, Subbotina I R, van Santen R A and Hensen E J M (2004), DRIETS study of the chemical state of modifying gallium ions in reduced Ga/ZSM-5 prepared by impregnation. I. Observation of gallium hydrides and application of CO adsorption as a molecular probe for reduced gallium ions , J Catal, 221, 263. 

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