For zinc oxide

Economic Aspects. Table 3 shows that mbber production is the largest market for zinc oxide the downturn in 1980 resulted from a drop in tire production because of the production trend to smaller tires, more importation of tires, and a recession. The drop in paint usage reflects the trend to water-base paints, which originally contained no zinc oxide. However, its growing use in such paints is based upon improved formulations based on zinc oxide. The increased use in agriculture is a result of the realization of the importance of zinc as a trace element. The rise in use of zinc-oxide-coated paper for photocopying is followed by a slackening in use because of a shift to plain-paper copiers. 

The test methods for zinc oxide impression pastes are outlined in ADA specification no. 16 and Federal specification U-1-500. 

The absorption spectrum of this nonstoichiometric phase forms the basis for the formerly much-used qualitative test for zinc oxide yellow when hot, white when cold . Alternatively, anion sites can be left vacant, e.g. ... 

Anodic photo currents for zinc oxide, 470 Anodic potential, oxidation of the polymer and, 395 Antimony... 

Brauer, G. M., McLaughlin, R. Huget, E. F. (1968). Alumimun oxide as a reinforcing agent for zinc oxide eugenol-o-ethoxybenzoic acid cements. 

If coefficients of ionization y and reflection of of atoms for zinc oxide film are known, we have... 

This conclusion is in agreement with experiments in which a smootb quartz and cellulose were used as substrates. For above materials the transfer of excitation energy of the dye into the substrate is low which is confirmed by intensive luminescence of adsorbed tripaflavine. Note, that the activation energy of emission of singlet oxygen is close for zinc oxide oxidized by oxygen atoms, quartz and cellulose and amounts to 5-10 kcal/mol [83]. 

Figure 22 shows the spectrum in the OH region for zinc oxide after admission of butene-1 at a pressure of about 8 mm (14). Spectrum (a), taken after 8 min exposures, shows two features (1) the strong surface hydroxyl band at 3615 cm-1 is shifted about 5 cm-1 to lower frequencies (2) a new band appears at 3587 cm-1. This new band, clearly an OH, appears to arise from dissociation of the adsorbed butene. Spectrum (b) shows the same region after exposure to the gas phase for 1 hr. It is clear that the OH band formed from butene grows with time detailed studies, however, reveal that there is little change after the first 20 min. Spectrum (c) was taken after 20 min evacuation. Two features are evident (1) in the absence of the gas phase the hydroxyl band of the zinc oxide has shifted back to its previous position (2) the OH band formed from butene is reduced somewhat in intensity. Spectrum (d) was taken after degassing for 90 min ... 

Figure 24 shows the cfs-butene isomerization over zinc oxide as a function of time at room temperature (7/). On a per unit area basis the initial rate at room temperature is 4 X 1010 molecules/sec cm2, a rate roughly one third that reported for alumina (69). Since the activation energy for alumina is less than that found for zinc oxide, this means that zinc oxide is comparable (on a per unit area basis) to alumina as an isomerization catalyst at slightly higher temperatures. 

Oxide zinc minerals activation using CuS04. The use of CUSO4 for zinc oxide activation and flotation is based on two different processes ... 

Cocoa butter needed for zinc oxide suppositories = 24 - 0.72 = 23.28 g... 

The electronic microscopy method on the EM-125 (fig. 1) for definition of ZnCFO particles size and characteristic of its surface was applied. Known zinc oxide was chosen as the object of comparison. The electronic photos of powders testify, that new composite and zinc oxide have external similarity under the form of particles, wide range on dispersiveness (0,4-6,0 microns for zinc oxide, fig. la 0,3-6,0 microns for ZnCFO, fig. lb) also contain as crystal as amorphous phases in their structure. 

Photopotential as a fimction of wave length of photons for zinc oxide and cadmium selenide electrodes in aqueous solutions X. = photon wave length. [From Williams, I960.]... 

Chinese white chem A term used in the paint industry for zinc oxide and kaolin used as a white pigment. Also known as zinc white. chTn nez wTt chinic acid See quinic acid. kin ik as ad chinoldine See quinoidine. ki noT.den chinone See quinone. kin on ... 

The 2003 AGGIE threshold limit value-time-weighted average (TLV-TWA) for zinc oxide fume is 5 mg/m with a short-term exposure limit (STEL) of lOmg/m the dust has a TLV-TWA of lOmg/m. ... 

Voltz and Weller 14S) measured the activity of chromic oxide for hydro-gen-deuterium exchange at —78° and —195°, after pretreatment at 5(X)° in an atmosphere of oxygen or hydrogen. They found the catalytic activity of the reduced state to be higher than that of the oxidized state, although the latter had a higher concentration of defects (positive holes) responsible for electrical conductivity. The relation between catalytic activity and conductivity is thus opposite to that for zinc oxide, although in both cases the activity appears to increase with the electron concentration. The interpretation advanced earlier for zinc oxide has also been extended to chromic oxide (Baker and Jenkins, 14S). 

In the absence of the dye the photocurrent is observed only in relatively short-wavelength light in the region of intrinsic absorption of semiconductors and is caused by photoexcitation of the electron-hole system of the semiconductor (cf. Part III). For zinc oxide (Eg = 3.2 eV) this region corresponds to wavelengths shorter than 400 nm for gallium phosphide (Eg = 2.2 eV), shorter than 550 nm. 

Flo. 1. Proposed energy-level diagram for zinc oxide. 

Morrison (31) has compared measurements of the Hall effect and of the resistance. The Hall voltage is inversely proportional to the average concentration of carriers in the material (24), and so, for zinc oxide, will be inversely proportional to the concentration of carriers in the large grains (Fig. 2) of the material. Figure 3 shows an example in which the resistance and the inverse of the Hall voltage measured on a sintered sample of zinc oxide are plotted as functions of the time. This illustrates that the number of carriers in the bulk of the sample may remain relatively constant, while the conductance varies widely, all at constant temperature. 

Further Comparison with Experiment. The model proposed here explains qualitatively most of the conductivity measurements reported to date for zinc oxide at temperatures between 20 and 500°C. It indicates why no simple correlation exists in certain cases. The time dependent reactions involving chemisorption and those attributed to O— levels can become hopelessly complex if measurements are made without proper consideration of the past history of the sample, the time factor, the temperature changes, and the oxygen pressure. 

A slurry of zinc powder in aqueous KOH was pumped through the cyclindrical cell whose outer surface comprised the air electrode and for which the negative current collector was an axial brass rod. The slurry was recirculated through the cell several times until an acceptable percentage of the theoretical capacity had been utilized (i.e. for zinc oxidation to soluble zincate). For recharge, the zincate ion was reduced to zinc powder either externally or in an electrolysis cell connected to the system. In this context... 

Direct evidence for the formation of allylic species on a solid surface was given by Dent and Kokes (21) for zinc oxide by using labeled propene, as expressed in Eqs. (10) and (11). In the IR absorption spectra, an O—D... 

Table 2.5. Fit parameters according to (2.24) for zinc oxide [67] in comparison with that of phosporous- and boron-doped silicon [103]...

Stromeyer analyzed the odd yellow zinc carbonate. What he discovered was a new element—cadmium. The cadmium caused the zinc carbonate to turn yellow when heated. The name cadmium comes from the ancient term for zinc oxide, cadmia. Zinc oxide is still available in pharmacies today. It is sold under the name of calamine lotion. Calamine lotion is a popular remedy for stopping the itch of sunburn or bug bites. 

Zinc oxides is mainly used in the rubber industry in which it serves as an activator in the vulcanization process. Its low hardness and high compatibility with polymers are important for its utilization in chemical materials. In its utilization in paints, its tendency to form zinc soaps, which hinder the attack of coatings by fungus and improve the aging resi.stance (UV-absorption), is important. Further application fields for zinc oxide are in copier paper, glues, pharmaceutical products, cosmetic products and dental cements. 

The American Conference of Governmental Industrial Hygienists threshold limit value-time-weighted average (TLV - TWA) for zinc chloride (as fume) is 1 mgm . The TLV - TWA for zinc oxide (as fume) is 5 mgm . ... 

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