Calcium salts observational study

Anionic Surfactants onto Kaolinite and lUite. In the investigation of the adsorption of sodium dodecylbenzenesulfonate (SDBS) and sodium dodecyl sulfate (SDS) onto asphalt covered kaolinite and illite surfaces, Siffert et al. [5S] observed Langmuir type I isotherms for SDS adsorption onto Na kaolinite and Na illite while the SDBS exhibited a maximum in adsorption with a decrease beginning near the CMC. Adsorption maxima were observed near the CMC for both surfactants in the Ca kaolinite and Ca illite systems. The adsorption behavior was explained as precipitation of the calcium salt of the surfactants (an idea supported by other studies), and the interaction of the aromatic ring in SDBS with the asphalt. This interaction favors desorption of the asphalt rather than adsorption of the SDBS. The amount of asphalt desorbed by SDBS was twice that desorbed by SDS. Other explanations for adsorption maxima include mixed micelle formation [55] and electrostatic repulsion of micelles from the bdayer covered surface [59]. 

The sodium and ammonium salts of PVSA are soluble in water but insoluble in organic solvents (6). The calcium salt is insoluble. Potentiometric titration studies indicate that PVSA is a strong acid that ionizes completely in water. Ion binding selectivity with alkali metals has been observed in viscosity and phase separation studies. Mark-Houwink-Sakurada (MHS) parameters ofK = 2.22 and a = 0.65 have been obtained for sodium PVSA in 0.5 M NaCl at 25°C. 

That different solvents, or mixtures of solvents, are critically associated with differences in selectivity coeflicients of calcium (or indeed all other types) of PVC ISEs based on organo-sensors is evident from Tables 3.2-3.10. It is highly desirable that the mediator should additionally function as a plasticizer for the PVC membrane. In view of the extensive use of PVC for fabricating the organic sensor type of ISEs, it is indeed fortunate that many of the necessary solvents fulfil this additional role. Thus di-octylphenyl phosphonate with, or without, a calcium salt is perfectly compatible with PVC. This requirement is rarely observed with alkan-l-ols which fail to plasticize the master membranes, and surface exudations are common (13). Despite this drawback, functional PVC ISEs can sometimes be fabricated (Tables 3.8,3.10) and extensive studies have been made on various solvents (Tables 3.2-3.10). 

The effect of two -nucleating agents, calcium salt of pimelic acid and quinacridonequinone, on the fractionated crystallization of PP microdroplets was studied. The microdroplets were produced by layer breakup on heating ultrathin films of PP/PS coextruded nanolayer films. Microdroplets produced from un-nucleated multilayered films exhibited fractionated crystallization at 110°, 90°, 60° and 40°C. PP microdroplets nucleated with Ca-Pim exhibited the P-form at 120°C in 200 nm samples while no P-peak was observed in other layer thicknesses. PP microdroplets nucleated with 0.01 wt% QQ and above showed crystallization peak for p-form of PP at 120°C for all layer thicknesses. 

A -(l-Haloalkyl)pyridinium halides have been advantageously employed in the Hantzsch multicomponent synthesis, yielding alkyl 1,4-dihydropyri-dine-3,5-dicarboxylates, which are a well-known class of calcium channel modulators (81AGE762). Tire halides readily interact with an excess of an ethyl 3-aminobut-2-enoate 82 (R = H) in dichloromethane at room temperature to afford the heterocycles 83 (R = H) in good to excellent yields (65-95%) (92T1263). Tliis observation has been exploited to perform a quantitative study of the reactivity of the salts (93CB1251).Tlie results have... 

The dehydration and interconversion reactions of the various forms of calcium sulphate [dihydrate, hemihydrate (a and 3 pseudo morphs) and anhydrous salt (hexagonal and orthorhombic structures)] have been studied by Ball et al. [281,590,591] who compared their observations with the available rate and microscopic data. The important features of the complicated behaviour found are summarized in the scheme [281]... 

Oral exposure to cyanide usually results from accidental, homicidal, or suicidal ingestion of cyanide salts. Sodium cyanide and potassium cyanide are the most frequently studied cyanide compounds. Copper cyanide, potassium silver cyanide, silver cyanide, and calcium cyanide are other compounds that humans could encounter through oral or dermal exposure. Cassava roots and certain fruit pits contain compounds that can be broken down to form cyanide. Cassava roots form the staple diet of some populations in Africa, Central and South America, and Asia. However, it must be noted that cassava roots are notoriously deficient in protein and other nutrients and contain many other compounds, in addition to cyanide, that could be responsible for some of the observed toxic effects. Thiocyanate is a metabolite of cyanide that is formed in the body after exposure to cyanide compounds. When possible, all oral exposures are expressed as mg CN/kg/day. 

The modern history of ion exchange began in about 1850 when two English chemists, Thompson(4) and Way(5), studied the exchange between ammonium ions in fertilisers and calcium ions in soil. The materials responsible for the exchange were shown later to be naturally occurring alumino-silicates 6. History records very much earlier observations of the phenomenon and, for example, Aristotle(7), in 330 BC, noted that sea-water loses some of its salt when allowed to percolate through some sands. Those who claim priority for Moses(8) should note however that the process described may have been adsorption ... 

Two examples where metal ions confer stability or increased activity in proteins are human deoxyribonuclease (rhDNase, Pulmozyme ), and Factor VIII. In the case of rhDNase, Ca2+ ions (up to 100 mM) increased the stability of the enzyme through a specific binding site (64). In fact, the removal of calcium ions from the solution with EGTA caused an increase in deamidation and aggregation. However, this effect was observed only with Ca+2 ions other divalent cations, Mg2+, Mn2+, and Zn2+, were observed to destabilize rhDNase. Similar effects were observed in Factor VIII. Ca2+ and Sr2+ ions stabilized the protein, whereas others such as Mg2+, Mn2+ and Zn2+, Cu2+, and Fe2+ destabilized the enzyme (65). In a separate study with Factor VIII, a significant increase in the aggregation rate was observed in the presence of Al3+ ions (66). The authors note that other excipients like buffer salts are often contaminated with Al3+ ions and illustrate the need to use excipients of appropriate quality in formulated products. 

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