Sodium structural stability

The use of alkali and alkaline earth group metal ions, especially those of sodium, potassium, magnesium, and calcium, for maintenance of electrolyte balance and for signaling and promotion of enzyme activity and protein function are not discussed in this text. Many of these ions, used for signaling purposes in the exciting area of neuroscience, are of great interest. In ribozymes, RNAs with catalytic activity, solvated magnesium ions stabilize complex secondary and tertiary molecular structure. Telomeres, sequences of DNA at the ends of chromosomes that are implicated in cell death or immortalization, require potassium ions for structural stabilization. 

R.A. Varin, Ch. Chiu, Structural stability of sodium borohydride (NaBH ) during controlled mechanical milling , J. Alloys Compd. 397 (2005) 276-281. 

Asymmetric Membrane Studies. In light of the results presented in the preceding two sections, plus those found in the literature (21-26,28), the decision was made to commence the asymmetric membrane studies with SPSF-Na(0.A2). The selection of the sodium salt polymer was based on the desire to limit ion exchange in desalination. The selection of D.S. of 0.A2 represents a compromise of hydrophilic/hydrophobic balance and structural stability. The exploration of asymmetric membranes cast from the pol3rmers of other salts and various D.S. values is planned for the future. 

Cass, A. and M. E. Sumner. 1982. Soil pore structural stability and irrigation water quality I-Empirical sodium stability model. Soil Sci. Soc. Am. J. 46 503-506. 

Several studies since then have supported this suggestion, and now it is widely accepted that conformational change/structural perturbation is a prerequisite for amyloid formation. Structural perturbation involves destabilization of the native state, thus forming nonnative states or partially unfolded intermediates (kinetic or thermodynamic intermediates), which are prone to aggregation. Mild to harsh conditions such as low pH, exposure to elevated temperatures, exposure to hydrophobic surfaces and partial denaturation using urea and guanidinium chloride are used to achieve nonnative states. Stabilizers of intermediate states such as trimethylamine N-oxide (TMAO) are also used for amyloidogenesis. However, natively unfolded proteins, such as a-synuclein, tau protein and yeast prion, require some structural stabilization for the formation of partially folded intermediates that are competent for fibril formation. Conditions for partial structural consolidation include low pH, presence of sodium dodecyl sulfate (SDS), temperature or chemical chaperones. 

Sodium ATPase pumping—Structure stabilization—Electrostatic effects on the reduction potential of distant centers... 

A novel Zn" complex bearing a mercaptoethyl group (98), the structure of which was determinated by X-ray crystallography, promoted the hydrolysis of sodium bis(p-nitrophenyl) hydrogenphosphate BNP. The rate of Zn" -promoted hydrolysis increases with the increase in pH, indicating that zinc-bound hydroxide is an active species for the hydrolysis of BNP". The major role of the thiolate coordination is structural stabilization rather then enzymatic activity... 

Sodium carboxymethyl cellulose (CMC, cellulose gum) is an anionic, water-soluble polymer (Figure 5.13). It is stable in a pH range of 4 to 10 and is compatible with most monovalent and divalent salts, as well as most anionic and nonionic materials. However, it is generally incompatible with cationic species due to its anionic nature. The structural stability of dispersions induced by CMC is highly dependent upon the concentration of the polymer. CMC is used as a thickener in toothpastes, skin creams, lotions, and food applications. The degree of... 

Blood Pressure and the Sodium lon/Potassium Ion Ratio Lewis Structures of Polyatomic Ions Lewis Structure, Stability, Multiple Bonds, and Bond Energies Lewis Structures and Resonance Lewis Structures and Exceptions to the Octet Rule... 

Of considerable importance are the structural motifs termed telomeres that have been identified at the ends of chromosomal DNA. Such motifs provide chromosomal stability and have been implicated in cell replications and a putative role in the mechanism of aging. Such structures (illustrated in Figure 6) are formed when four guanine bases form stable four-stranded helices. Such tetrads are stabilized principally by potassium ion, although sodium ion stabilization has also been characterized." " A cubic coordination motif is generated by the eight 06 atoms from the guanine bases. 

J. P. Quirk, Some physico-chemical aspects of soil structural stability—A review, in Modification of Soil Structure (W. W. Emerson, R. D. Bond, and A. R. Dexter, eds.) Wiley, Chichester, U.K., 1978. Y. Chen and A. Banin, Scanning electron microscope (SEM) observations of soil structure changes induced by sodium-calcium exchange in relation to hydraulic conductivity, Soil Sci. 120 428 (1975). Y. Chen, J. Tarchitzky, J. Brouwer, J. Morin, and A. Banin, Scanning electron microscope observations on soil crusts and their formation, Soil Sci. 130 49 (1980). 

Walter D, Karyasa IW (2005) Synthesis and characterization of cobalt monosilicide (CoSi) with CsQ structure stabilized by a f -SiC matrix. Z anorg allgem Chem 631 1285-1288 Sato-Sorensen Y (1983) Phase transitions and equations of state forthe sodium htilides NaF, NaCl, NaBr, and Nal. J Geophys Res 888 3543-3548... 

Alak and Armstrong (107,108,112,113) investigated the influence of different silicas and binders on the separation behavior of P-cyclodextrin TLC plates. Besides nine racemates, three diastereomeric compounds and six structural isomers were separated. Wilson (109) impregnated silica plates with a 1% solution of P-CD in ethanol-dimethylsulfoxide (80 20 by volume) racemic mandelic acid was barely separated, and the antipode separation of P-blockers was not possible. Armstrong et al. (110) were the first to describe application of P-cyclodextrin as a chiral eluent additive for separations on reversed-phase TLC plates. The success of separation was strongly dependent on type and quantity of modifier applied, but above all on the concentration of P-CD. The low solubility of 3-CD in water (0.017 M, 2S C) can be improved by addition of urea sodium chloride stabilizes the binder of the RP plates. Compared to 3-CD bonded phases, a reversed retention behavior was noticed, the D-enantiomer eluting above the L-isomer. The separation of steroid epimers and other diastereomeric classes of compounds is also possible with this technique. Hydroxypropyl and hydroxyethyl P-... 

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