Calcium stability

Although CCP represents only about 6% of the dry weight of the casein micelle, it plays an essential role in its structure and properties and hence has major effects on the properties of milk it is the integrating factor in the casein micelle without it, milk is not coagulable by rennet and its heat and calcium stability properties are significantly altered. In fact, milk would be a totally different fluid without colloidal calcium phosphate. 

Calcium chloride Skeletal muscle spasms Calcium stabilizes excitable membranes appears to decrease excitability threshold in peripheral nerves and skeletal muscle 2°/o aqueous solution from positive pole ... 

The typical process for producing a 42% high-fructose syrup is shown in Figure 21.8.32 A starch solution at about 35% solids and a pH of about 6.5 is drawn into a steam jet at 180°F (82°C) in the presence of a calcium-stabilized, thermostable alpha-amylase. The slurry is maintained at this temperature through a series of loops for 3-5 minutes and then cooled to 95°C (200°F) in a secondary reactor, where further alpha-amylase additions occur. A holding time of up to 120 minutes in the secondary reactor produces a solution of approximately 12 DE. The pH is adjusted to about 4.3... 

The basic elements of a SOFC are (1) a cathode, typically a rare earth transition metal perovskite oxide, where oxygen from air is reduced to oxide ions, which then migrate through a solid electrolyte (2) into the anode, (3) where they combine electrochemically with to produce water if hydrogen is the fuel or water and carbon dioxide if methane is used. Carbon monoxide may also be used as a fuel. The solid electrolyte is typically a yttrium or calcium stabilized zirconia fast oxide ion conductor. However, in order to achieve acceptable anion mobility, the cell must be operated at about 1000 °C. This requirement is the main drawback to SOFCs. The standard anode is a Nickel-Zirconia cermet. 

Musci and Berliner (1985b) concluded that apo-a-lactalbumin is more efficient as the modifier protein in the lactose synthase system than is the Ca(II)-bound form. They found that Vniax for the apo form shows a 3.5-fold increase over that for the Ca(II)-bound form, but there is no difference in (app.) between the two forms. They also confirmed that calcium stabilizes the protein against thermal denaturation (see Section IX,E), but that zinc is crucial in shifting the protein toward the apo-like form that is optimally active in lactose synthase. Their model is summarized schematically in Fig. 9. 

ExtraceHuiar calcium provides calcium ion for the maintenance of intracellular calcium, bone mineralization, blood coagulation, and plasma membrane potential. Calcium stabilizes the plasma membranes and influences permeability and excitability. A decrease in the serum free calcium concentration causes increased neuromuscular excitability and tetany an increased concentration reduces neuromuscular excitability. 

How does calcium act at the molecular level to stabilize cell membranes Probably it interacts with phospholipids in the membrane to limit ion permeability since phospholipid must be included in artificial membranes in order for calcium to have a stabilizing effect (13, 14). However, there is no firm evidence that calcium stabilizes native biological membranes by interacting with phospholipids, and the structural or functional impact of calcium on various biological membranes is impossible to predict based on lipid composition (15). 

The reactions between cerium trichloride and oxide ions were initially studied in the pure KCl-NaCl equimolar mixture at 1000 K by the method of potentiometric titration using a calcium-stabilized zirconia membrane electrode. The titration curves clearly demonstrated the existence of the soluble cerium oxychloride CeO+ and precipitated cerium oxide ... 

Metal halides have also been used as CVD precursors to YBCO films by Ottosson et al. at the University of Uppsala [I87. The sublimation temperatures of the YCI3, Bah. and CuCI precursors were 820°C, 950 C, and 340 C. respectively. These were used in combination with gaseous H2O/O2 at 20Torr in the deposition chamber to grow c-axis oriented YBCO films in situ on calcium stabilized zirconia substrates at 750-950°C. The YBCO films exhibited 7 . = 40 K [187]. 

The tubular design is probably the best-known design. It has been developed by Westinghouse (now Siemens Power generation) [8]. The first concept that was pursued by Westinghouse consisted of an air electrode supported fuel cell tube. In earlier days the tubes were made from calcium-stabilized zirconia on which the active cell components were sprayed. Nowadays this porous supported tube (PST) is replaced by a doped lanthanum manganite (LaMn) air electrode tube (AES) that increases the power density by about 35 %. The LaMn tubes are extruded and sintered and serve as the air electrode. The other cell components are deposited on this construction by plasma spraying. 

D. Calcium stabilizes cardiac cell membranes in hyperkalemic states. 

Stabilities determined in this way are dramatically dependent upon conditions. Buffer type, pH, and ionic strength can have major effects, as well as agents such as substrate, product, cofactors, and metal ions (especially calcium). Stability comparisons made between enzymes on this basis must be regarded as approximations only, and the conditions carefully defined. 

Hidaka et al. [77] reported that amphoteric Af-(2-hydroxyethyl)- -(2-hydroxyalkyl)-P-alanines s cmc values greatly depend on the nature of the electrolytes added to its nearly neutral aqueous solution, and that the cmc value decreased in the following order NaCl > CaClj > Na2S04. Also, their calcium stability is superior to that of A-dodecyl-P-alanines. The effect of pH on this amphoteric amino acid surfactant was smdied in the presence of 0.1 M NaCl [78] and the results showed that the cmc value increased on the acidic side below the isoelectric point pi = 6.8 and remained almost unchanged on the alkaline side. Examination of the configuration with molecular models indicates that the cationic ionization of the amino group on the acidic side probably takes place within the micelle, whereas under alkaline circumstances the anionic ionization of the carbonyl group occurs on the micellar surface. This makes the electrostatic potential for ionization different on the acidic and alkaline sides. 

---