Cations calcium

In the physical separation process, a molecular sieve adsorbent is used as in the Union Carbide Olefins Siv process (88—90). Linear butenes are selectively adsorbed, and the isobutylene effluent is distilled to obtain a polymer-grade product. The adsorbent is a synthetic 2eohte, Type 5A in the calcium cation exchanged form (91). UOP also offers an adsorption process, the Sorbutene process (92). The UOP process utilizes ahquid B—B stream, and uses a proprietary rotary valve containing multiple ports, which direct the flow of Hquid to various sections of the adsorber (93,94). The cis- and trans-isomers are alkylated and used in the gasoline blending pool. 

Application of the reaction to the 2-azidobenzoyl derivative of diethylene glycol monomethyl ether 92, in a mixture of tetrahydrofuran and diethylene glycol monomethyl ether as the nucleophile, affords 2-(2-methoxyethoxy)ethyl 2-[2-(2-methoxyethoxy)ethoxy]-37/-azepine-3-carbo-xylate (93), which displays metal cation complexing properties towards lithium, potassium, and. to a lesser extent, barium and calcium cations.198... 

Calcium cations 144,145, 311, 312 Calibration of the wavelength scale 21 Campesterol 213 Cannabinoids 288,291 Canrenone 411 Capsaicinoids 65 Carbadrine 76... 

With data averaged in point group m, the first refinements were carried out to estimate the atomic coordinates and anisotropic thermal motion parameters IP s. We have started with the atomic coordinates and equivalent isotropic thermal parameters of Joswig et al. [14] determined by neutron diffraction at room temperature. The high order X-ray data (0.9 < s < 1.28A-1) were used in this case in order not to alter these parameters by the valence electron density contributing to low order structure factors. Hydrogen atoms of the water molecules were refined isotropically with all data and the distance O-H were kept fixed at 0.95 A until the end of the multipolar refinement. The inspection of the residual Fourier maps has revealed anharmonic thermal motion features around the Ca2+ cation. Therefore, the coefficients up to order 6 of the Gram-Charlier expansion [15] were refined for the calcium cation in the scolecite. 

It should be pointed out that the addition of substances, which could improve the biocompatibility of sol-gel processing and the functional characteristics of the silica matrix, is practiced rather widely. Polyethylene glycol) is one of such additives [110— 113]. Enzyme stabilization was favored by formation of polyelectrolyte complexes with polymers. For example, an increase in the lactate oxidase and glycolate oxidase activity and lifetime took place when they were combined with poly(N-vinylimida-zole) and poly(ethyleneimine), respectively, prior to their immobilization [87,114]. To improve the functional efficiency of entrapped horseradish peroxidase, a graft copolymer of polyvinylimidazole and polyvinylpyridine was added [115,116]. As shown in Refs. [117,118], the denaturation of calcium-binding proteins, cod III parvalbumin and oncomodulin, in the course of sol-gel processing could be decreased by complexation with calcium cations. 

Calcium is produced by two methods. One method is the electrolysis of calcium chloride (Ca + 2C1 —> CaCy as the electrolyte at a temperature of 800°C, during which process metallic calcium cations (Ca ) are deposited at the cathode as elemental calcium metal. Calcium can also be produced through a thermal process under very low pressure (vacuum) in which lime is reduced by using aluminum. 

Pectins are best known for their ability to form gels (6), a property which often involves intermolecular binding mediated by calcium cations (7). The principal commercial use of pectin is in the preparation of jelly and jam products (8). Pectins provide firmness in fresh fruits and vegetables (9-11). Historically, natural tobacco pectins also have been used as binders to prepare reconstituted sheets from tobacco by-products that are then incorporated into cigarette filler or cigar wrappers (12-14). 

This result is directly proportional to the minimum number of carboxylic acid sites required to form a stable junction zone on polymers. The number of calcium cations bound must also be directly related to the stability of the junction and its thermoreversibility. Finally, it must be also pointed out that it is not the pH, but the degree of neutralization, a, which controls calcium binding. 

By drawing cubes with fluoride ions at each corner as has been done in Figure 1.39(b), you can see that there is an eightfold cubic coordination of each calcium cation. Indeed, it is possible to move the origin and redraw the unit cell so that this feature can be seen more clearly as has been done in Figure 1.39(c). The unit cell is now divided into eight smaller cubes called octants, with each alternate octant occupied by a calcium cation. 

In this section the solubilities of NaCl, CaCl2, Na2C03 and CaC03 are compared to investigate the effects of having doubly charged ions in a compound. The solubilities of the compounds are given in Table 3.17 in terms of mass % and molar concentration. Sodium and calcium cations are chosen for this comparison because they have almost identical ionic radii Na h 102 pm, Ca2+ 100 pm. 

Inserted L-rhamnopyranosyl units may provide the necessary irregularities (kinks) in the structure required to limit the size of the junction zones and produce a gel. The presence of side chains composed of D-xylosyl units may also be a factor that limits the extent of chain association. Junction zones are formed between regular, unbranched pectin chains when the negative charges on the carboxylate groups are removed (addition of acid), hydration of the molecules is reduced (addition of a cosolute to a solution of HM pectin), and/or pectinic acid polymer chains are bridged by multivalent, eg, calcium, cations. 

Organophosphates are far more resistant to hydrolysis than polyphosphates. Thus, the films they form remain intact for longer periods of time in normal water environments. Strong oxidizers in the water such as chlorine, however, rapidly degrade AMP and phosphate esters. HEDP is more resistant to oxidizers. The presence of zinc or calcium cations stabilize organophosphate protective films and prolong their lives (Roti 1985). While phosphates are more environmentally benign in many ways than hexavalent chromium... 

Fig. 8. The EF hand represents a widespread Ca2+ binding motif that was first characterized in calmodulin. Generally, EF hands are observed in pairs. Each consists of two short stretches of o-helix connected by a loop. Two possible sets of ligands have been identified through which calcium cations bind to the residues comprising the loop (see text). This figure illustrates the structural forms observed that relate to different Ca2+ binding states (PDB closed, 1GFC open, 1GLL semi-open, 1WDC). Figure from http //structbio.vanderbilt.edu.chazin/cabp database/seq.

The action of chlorine in alkaline media is much slower than that of bromine. Lewin29 reported that the rate of oxidation of D-glucose at pH 9.8 by hypobromite is 1360 times higher than that by hypochlorite at the same pH. For cellulose, the ratio is much smaller (33 to 1). The complexity of the latter system is, however, revealed by the variability of this ratio over the pH range of 8-13 at pH 6-7, the action of hypochlorite is actually slightly faster than that of hypobromite. Maltodextrins and starch have been oxidized with alkaline sodium hypochlorite. The resulting oxidized polysaccharide formed stable complexes with calcium cations.30... 

We have also recently discovered that added calcium laurate is able markedly to enhance the mechanical stability of natural rubber latex (2.). This observation is surprising, partly because of the low solubility of calcium laurate in water, and partly because calcium ions are known to be powerful destabilisers of natural rubber latex (j ). It indicates that the stabilising effect of the laurate anion is much greater than the destabilising effect of the calcium cation. 

As you recall, molecules are comprised of atoms chemically bonded into a discrete and identifiable unit. There are no ionic molecules, because every cation is attracted to every anion, so there are no identifiable ion pairs that belong exclusively to each other. Therefore, the formula of an ionic compound is an empirical formula. That is, the formula of an ionic compound lists the simplest ratio of cations to anions necessary to achieve electrical neutrality. For example, calcium oxide contains Ca2+ ions and O2- ions. While the formulas CaO and Ca202 both represent electrically neutral combination of ions, the subscripts in the latter formula have a common factor of 2. Therefore, Ca202 is not the simplest ratio of calcium cations to oxide anions. Therefore, the formulation of calcium oxide as Ca202 is incorrect. The correct empirical formula of calcium oxide is CaO. 

Myers AG, Snoeyink VL, Snyder DW. 1985. Removing barium and redium through calcium cation exchange. Am Water Works Assoc J 77 60-66. 

Some compounds contain ions that are made from more than one atom. These ions are called polyatomic ions. (The prefix poly means many. ) Calcium carbonate, CaC03, which is found in chalk, contains one calcium cation and one polyatomic anion called carbonate, C032-. 

To grow sufficient crops, you will need large amounts of calcium phosphate fertilizer. You can make this compound by combining the phosphate solution in the stream with calcium cations. Simulate this reaction in the laboratory. Design a procedure to find the mass of dry calcium phosphate precipitate. Mix 50 mL of a 0.10 mol/L aqueous solution of sodium phosphate with sufficient calcium nitrate to obtain a precipitate. Filter the precipitate, dry it, and determine its mass. 

Aluminum cation % Phosphorus cation Oxygen atom Lanthanum cation Calcium cation... 

---