Other Inorganic Solutions

The etching processes in all alkali hydroxides are similar to those in a KOH solution, namely, free H2O and OH are the active agents. It has been suggested that the difference among solutions such as NaOH, LiOH, NH4OH, RbOH and CsOH is mainly 

FIGURE 7.16. (100) silicon etch rate with respect to the initial NH4OH concentration in water. After Schnakenberg et aV  

FIGURE 7.17. Etch rate of a silicon wafer as a function of the pH of an aqueous solution of NH, and NaOH at 70°C. After van den Meerakker and van den Straaten. (Reproduced by permission of The Electrochemical Society, Inc.) 

Formation of pyramidal hillocks bounded by (111) crystal planes on the (100) wafer is a problem in NH4OH solutions for all concentrations, temperatures, stirring 

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Plasmids can be introduced into ceUs by several methods. The most common method is transformation, where the recipient ceUs are made competent to receive DNA by washing with a solution of or other inorganic ions. Then the naked DNA is added direcdy a fraction of the ceUs take... 

Other Inorganics. Inorganic species in solution have been studied very effectively by Raman spectroscopy. Work in this area includes the investigation of coordination compounds (qv) of fluorine (qv) (40), the characterization of low dimensional materials (41) and coordinated ligands (42), and single-crystal studies (43). Several compilations of characteristic vibrational frequencies of main-group elements have been pubflshed to aid in the identification of these species (44,45). 

Most acids are corrosive to aluminium-base materials. The oxidising action of nitric acid at concentrations above about 80%, however, causes passivation of aluminium. Very dilute and very concentrated sulphuric acid dissolves aluminium only slowly. Figures 4.4 and 4.5 give corrosion data at various concentrations for these two acids. The corrosion rates of aluminium in other inorganic acids in dilute solution are shown in Fig. 4.6. Boric acid also exerts little attack on aluminium, while a mixture of chromic and phosphoric acids can be used for the quantitative removal of corrosion products from aluminium without attacking the metal. 

A process involving water electrolysis is the production of heavy water. During cathodic polarization the relative rates of deuterium discharge and evolution are lower than those of the normal hydrogen isotope. Hence, during electrolysis the solution is enriched in heavy water. When the process is performed repeatedly, water with a D2O content of up to 99.7% can be produced. Electrochemical methods are also used widely in the manufacture of a variety of other inorganic and organic substances. 

The development of synthetic routes to new polyphosphazene structures began in the mid 1960 s (2-4). The initial exploratory development of this field has now been followed by a rapid expansion of synthesis research, characterization, and applications-oriented work. The information shown in Figure 3 illustrates the sequence of development of synthetic pathways to polyphosphazenes. It seems clear that this field has grown into a major area of polymer chemistry and that polyphosphazenes, as well as other inorganic macromolecules, will be used increasingly in practical applications where their unique properties allow the solution of difficult engineering and biomedical problems. 

Other inorganic and organic compounds are brought into solution by the decomposition of their parent materials. Rocks and minerals will be decomposed by physical, biological, and chemical mechanisms. Enzymes released into the soil solution by microorganisms will decompose insoluble organic... 

The birth of a crystal and its growth provide an impressive example of nature s selectivity. In qualitative analytical chemistry inorganic solutes are distinguished from each other by a separation scheme based on the selectivity of precipitation reactions. In natural waters certain minerals are being dissolved, while others are being formed. Under suitable conditions a cluster of ions or molecules selects from a great variety of species the appropriate constituents required to form particular crystals. 

Kit solution for the determination of toxic anions (e.g., arsenate, arsenite, azide, or cyanide) and other inorganic and organic anions with indirect UV detection... 

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