Acidic fluxes

K2S2O7 300 Ft or porcelain Acid flux for insoluble oxides and oxide-containing samples... 

Naturally, the flux employed will depend upon the nature of the insoluble substance. Thus acidic materials are attacked by basic fluxes (carbonates, hydroxides, metaborates), whilst basic materials are attacked by acidic fluxes (pyroborates, pyrosulphates, and acid fluorides). In some instances an oxidising medium is useful, in which case sodium peroxide or sodium carbonate mixed with sodium peroxide or potassium nitrate may be used. The vessel in which fusion is effected must be carefully chosen platinum crucibles are employed for... 

Ketogenesis is regulated at three cmcial steps (1) control of free fatty acid mobihzation from adipose tissue (2) the activity of carnitine palmitoyltransferase-1 in hver, which determines the proportion of the fatty acid flux that is oxidized rather than esteri-fied and (3) partition of acetyl-CoA between the pathway of ketogenesis and the citric acid cycle. 

For dissolving particularly difficult metal oxides, the acidic flux potassium pyrosulfate (K2S207) may be used. 

The relative humidity thus measured was 32% and the carbon dioxide concentration was 360 ppm. Trade (B) is a blowup of the 2060-2260 cm l region, where absorption due to CO and N2O can be recognized. Typical background concentrations of CO (0.28 ppm), N2O (0.45 ppm) and as well CH4 (1.6 ppm) were measured. In addition, a trace amount of HCl (0.12 ppm) was detected, as will be described in detail in subsequent paragraphs. This contaminant resulted from acid fluxed soldering being conducted in the room. 

Type 2 diabetes is characterized by tissue resistance to the action of insulin combined with a relative deficiency in insulin secretion. A given individual may have more resistance or more beta-cell deficiency, and the abnormalities may be mild or severe. Although insulin is produced by the beta cells in these patients, it is inadequate to overcome the resistance, and the blood glucose rises. The impaired insulin action also affects fat metabolism, resulting in increased free fatty acid flux and triglyceride levels and reciprocally low levels of high-density lipoprotein (HDL). 

Table 15.2 shows that for estradiol, the ER during electroporation (8.7) was greater than during iontophoresis (2.5, P < 0.05). In contrast, the apparent L-glutamic acid fluxes were... 

In the Front Range of the Rocky Mountains, the N enrichment of alpine catchments from increased atmospheric N deposition from agricultural and urban development on the plains is an important environmental and resource issue (Williams et al., 1996). The difference in N content (about 0.5-1.0% for terrestrially derived DOM vs. about 2-3% for microbially derived DOM) could be significant in terms of estimating the contribution of dissolved fulvic acid flux to the yield of N from alpine and subalpine catchments in the Rocky Mountains. The example for this alpine catchment illustrates the potential usefulness of the fluorescence index in field studies addressing applied issues related to environmental management. 

Milner, J. L., B. Vink, and J. M. Wood. 1987. Transmembrane amino acid flux in bacterial cells. CRC Critical Reviews in Biotechnology 5 1—47. 

Soft-soldering of copper, iron, steel, and brass objects of large size is usually accomplished by the use of a burner or hand torch, with an acid flux—frequently a concentrated aqueous solution of zinc chloride and ammonium chloride (2 1 ratio)—brushed onto the hot metal concurrently with the addition of solder. Initially, heat should be applied around the area to be soldered but not directly on the region to be soldered. If the region to be soldered is heated too much without the application of flux, an oxide coating will form that can make proper surface adhesion impossible. The surfaces to be joined should be pretinned if possible, and excess solder is shaken off or wiped off with a cloth. The two surfaces to be joined are then placed in contact and heated with the torch until the solder begins to flow more solder is then added as required, and the pieces are allowed to cool undisturbed. The finished work should be washed thoroughly with water to remove the flux. 

The conventional synthesis of rare earth borates, such as solid-state reaction between rare earth oxides and boric acid, flux-aided solid-state reaction at temperatures above 1000 °C, and milling, leads to a poor crystalline integrity and damaged luminescent properties. Other methods like coprecipitation methods through wet process (Boyer et al., 1999) are also studied. 

Different fluxes can be used. Basic fluxes employed for the attack of acidic materials include carbonates, hydroxides, peroxides, and borates. Oyrosulfates can be used as acidic flux. If an oxidizing flux is required, sodium peroxide can be used. As an alternative, small quantities of alkali nitrates or chlorates can be mixed with sodium carbonate. Basic and acidic fluxes are dissolved in an acid or basic medium, respectively. 

Cotner, J. B., and Gardner, W. S. (1993). Heterotrophic bacterial mediation of ammonium and dissolved free amino-acid fluxes in the Mississippi River plume. Mar. Ecol. Prog. Ser. 93, 75—87. 

The Metallurgy of Iron. The ores of iron are usually first roasted, in order to remove water, to decompose carbonates, and to oxidize sulfides. They are then reduced with coke, in a structure called a blast furnace (Fig. 26-2). Ores containing limestone or magnesium carbonate are mixed with an acidic flux (containing an, excess of silica), such as sand or clay, in order to make a liquid slag. Limestone is used as flux for ores containing an excess o silica. The mixture of ore, flux, and coke is introduced at the top of the blast furnace, and pre heated air is blown in at the bottom through tuyeres. As the solid... 

All leachate flows were set at 0.2 ml/min. Acetic acid strengths of 0.05 N and 0.20 N were used to create acid fluxes of 1.0 and 2.0 meq/g/day. Leachates from the columns were collected in Erlenmeyer flasks. Leachate was filtered through a 0.45 /xm filter, and the metal concentrations determined. 

Pt Acidic flux for silicates and oxides where alkali metals are to be determined... 

Potassium pyrosulfate is a potent acidic flux that is particularly useful for attacking the more intractable metal oxides. Fusions with this reagent are performed at about 400°C at this temperature, the slow evolution of the highly acidic sulfur trioxide takes place ... 

Acidic flux A salt that exhibits acidic properties in the molten state used to convert refractory substances into water-soluble products. 

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