Wide Variety Of Impurities Research Articles

Sources of fluids and material for gold and antimony mineralization in the Adychanskii ore region (East Yakutia, Russia)

The peculiarities of fluid inclusions; the O and C isotope composition of host rocks, vein minerals, and inclusions; and the S and Pb isotope composition of sulfides allowed us to distinguish two groups of fluids with a similar temperature, salinity, and source of the aqueous part produced upon metagenesis and mobilized during collisional events. Quartz-A precipitates from the CO2–H2O hydrocarbonate–Na fluid with a salinity of 7–10 wt % eq. NaCl at a depth of ∼6 km (290–340°C, 1550 bar). Regeneration of quartz (quartz-C), precipitation of quartz-B, and quartz-AB with carbonate and chlorite occurred at a depth from 3.5 to 1.5 km (250–380°C, 1250–900–350 bar) from CO2–CH4–N hydrous sulfate–hydrocarbonate Na–Mg fluids with Cl–, Ca, and K and a salinity of 5–10 wt % eq. NaCl, and a wide variety of impurities. The localization of veins in sinistral shear dislocations and strong heterogeneity in the P–T conditions allow us to explain the formation of fluid-2 by the postcollisional events.

Facile and Rapid Determination of Contamination in Sulphur Pesticide Formulations by Liquid Chromatography–Tandem Mass Spectrometry

Up to 7% of pesticide products in the European market are illegal, counterfeit or of poor quality. As a result, regulatory authorities are required to determine a wide variety of impurities in many different pesticide formulations. A simple, rapid and exceptionally reliable LC-MS-MS method for the determination of carbendazim residual quantities in sulphur formulations, used in organic agriculture, has been developed and validated. Linearity of response was established (R (2) = 0.9997) over a wide range of concentrations (0.01-2 microg/mL). Recovery ranged from 94% to 101%. LOD and LOQ were 0.003 microg/mL and 0.005 microg/mL, respectively, and lack of interference was confirmed.

Electronic Theory of Gettering and Passivation of Impurities in Semiconductors

ABSTRACTWe calculate the interaction (segregation) energies Egegr between the extended lattice defects (dislocations and grain boundaries) and impurity atoms in semiconductors by using a microscopic electronic theory. In particular, we use the tight-binding recursion method coupled to the generalized zeros-and poles method and investigate the interaction between the extended lattice defects and various kinds of the impurity atoms in semiconductors (Si). For the systematic understanding of the impurity gettering, we consider a wide variety of impurities, both sp-valence and transition metal impurities, Ti, V, Cr, Mn, Fe, Co, Ni and Cu. We will show that the variation of the gap states plays an important role in determining the interaction energy Esegr between the impurity atom and the extended lattice defects- We also discuss the passivation of the extended lattice defects by interstitial light impurities like hydrogen in Si crystal, we present a simple physical interpretation of the impurity gettering and passivation in semiconductors.

Characterization of reactive impurities in methanol, ethanol, and 2-propanol by monitoring the activities of added ionic probes with ion selective electrodes

The presence of reactive impurities compromises many important applications of solvents. It is shown that a wide variety of impurities can be detected and determined by adding such highly reactive probes as hydrogen, methoxide, copper(II), mercury(II), and fluoride ions and monitoring their activities over an appropriately wide range with the corresponding ion selective electrodes. The results for the alcohols show that typical reagent grades of these solvents contain amines at the 10/sup -5/ - 10/sup -4/ M (1-10 ppm) level as well as other reactive impurities. This approach is applicable to most polar solvents. It has the overriding merits that it detects impurities on the basis on their reactivities (rather than only their concentrations) and that its lower detection limit is self-adjusting in that it is lowest (most favorable) in the very solvents in which impurities are most harmful, i.e., relatively inert solvent. In such solvents, its lower detection limit can be much lower than that attainable with gas chromatography.

The magnetic disturbances associated with substitutional impurities in nickel

The disturbances in magnetization around a wide variety of impurities in nickel (Zn, Al, Ga, Si, Ge, Sn, Sb, non-transition metals; Nb, Mo, Ru, Rh, 4d elements; W, Re, 5d elements) have been measured by the neutron diffuse scattering method. This work is an extension of an earlier study (by Collins and Low) of the 3d transition elements V, Cr, Mn, Fe dissolved in nickel. Two distinct kinds of magnetization distribution have been observed. In one category (Mn, Fe, Rh) the magnetic disturbance is positive and confined to the impurity site. The other solutes lead to a widespread negative magnetic disturbance extending some five angstroms into the nickel lattice. With the exception of V, the individual scattering curves of the second class approximately superpose, when normalized at a single point. This leads to the conclusion that the spatial form of the moment disturbance in the nickel matrix is similar for Zn, Al, Ga, Si, Ge, Sn, Sb, Nb, Cr, Mo, Ru, W and Re and suggests that this wide variety of impurities affects the nickel matrix through the same mechanism. Differences between the impurities show up in the strength of the disturbances. In discussing the nature of these magnetic defects, a molecular field theory model is used to illustrate a possible mechanism for linking the spatially widespread losses of moment with a more localized driving force. A transition element solute gives rise to a widespread negative defect or to a positive disturbance confined to the solute site depending on whether or not formation takes place of the bound impurity states proposed by Friedel.

Storage battery electrolytes

Experiments have been in progress at the Bureau of Standards to determine quantitatively the effect produced by a wide variety of impurities on the rate of sulphation of storage battery plates. The method for making the determinations involves measuring the changing weight of the plates suspended in the solution. The various impurities are classified according as they affect the negative plates, the positive plates or both. A discussion is given also of certain combinations of impurities. Sodium and magnesium sulphates which are sometimes added to the electrolyte to “improve” the behavior of the battery are without effect on the rate of sulphation. It is important that some generally recognized specifications for storage battery electrolytes should be established.

Storage Battery Electrolytes

Experimtents have been int progress at the Bureau of Standards to determine quantitatively the effect produced by a wide variety of impurities on the rate of sulphation of storage battery plates. The method for making the determinations involves measuring the changing weight of the plates suspended in the solution. The various impurities are classified according as they affect the negative plates, the positive plates or both. A discussion is given also of certain combinations of impurities. Sodium and magnesium sulphates which are sometimes added to the electrolyte to ``improve'' the behavior of the battery are without effect on the rate of sulphation. It is important that some generally recognized specifications for storage battery electrolytes should be established.