NH4HCO3 Solution Research Articles

A flow EPR study of deformation and orientation characteristics of erythrocyte ghosts: effects of lysing and resealing conditions.

The effects of various conditions in lysing and resealing the red cell membrane on the degree of ghost deformation and orientation in flow are investigated using the flow EPR and spin-label method. The relatively low deformability of the standard ghost, which is lysed and resealed, respectively, in hypotonic and isotonic NaCl-Tris buffer, is markedly enhanced by the presence of Mg-ATP, chlorpromazine, or Ca2+ ion during resealing. The effect is concentration dependent, and there is an optimal level for each treatment. Chlorpromazine and Ca2+ are also effective when added to the resealed ghosts. Mg2+ ion shows an opposite effect reducing the ghost deformability in flow at all concentrations. An isotonic lysis in NH4HCO3 solution with less osmotic stress substantially raises ghost deformability above that of the standard ghosts. These results are interpreted on the basis of a misalignment between the bilayer leaflets that is probably brought about during hypotonic lysis and its recovery to the nearly normal bilayer state by the agents used during or after resealing. The novel finding of deformability enhancing effect of calcium is assumed to be caused by the electrostatic expansion of the inner layer relative to the outer leaflet. The explanations are supported by the resealed ghost shapes observed before and after the treatments; shape recovery from the monoconcave spheroid toward biconcave discoid is observed in most cases concomitantly with improvements of flow characteristics.

Formation and Thermal Decomposition of Al(NH<sub>4</sub>)CO<sub>3</sub>(OH)<sub>2</sub> Acicular Microcrystals

In order to prepare acicular particles of Al(NH4)CO3(OH)2 (AACH), ammonium alum (AA) and NH4HCO3 (AHC) solutions were mixed at room temperature, and the precipitate was aged in the mother liquor at 60°-120°C in a closed vessel. Effects of ageing conditions on kind of products and their shape and size were investigated. AACH was formed with an excessive amount of AHC over the stoichiometry. Insufficient amounts of AHC produced boehmite. The AACH particles were single crystalline and acicular or lath-like, and long and short axes corresponded to crystallographic c and a axes, respectively. The length of particles was increased by the addition of acid solution such as H2SO4, HCl and HNO3 to the mother liquor in which the precipitates were aged. The AACH particles seemed to be formed from the reaction of amorphous substances, which formed at room temperature, with the ageing solution during ageing at temperatures of 60°-120°C. Gamma-Al2O3 particles obtained by thermal decomposition of AACH particles at 1000°C possessed acicular shape of the parent crystals.

Ascorbic Acid Retention and Organoleptic Quality of Green Vegetables Cooked by Several Techniques Using Ammonium Bicarbonate1

Five fresh green vegetables were cooked in small amounts of water (control), small amounts of water to which ammonium bicarbonate (NH4HCO3) had been added, and four of the five were also cooked in large amounts of water. Samples were analyzed for pH, titratable acidity, reduced and dehydro ascorbic acid, and color difference. The addition of NH4HCO3 to small amounts of water was found to be a more effective method of preserving color and ascorbic acid than the use of large amounts of water.Four commercially frozen green vegetables were cooked by package directions (control), in NH4HCO3 solution, and three of the four in ammonium bicarbonate ‐ calcium acetate (NH4HCO3 ‐ CaAc2) solution. The vegetables were analyzed for the same parameters described for fresh vegetables. Use of NH4HCO3 was again found to be an effective method for retention of color during cooking. The addition of CaAc2 prevented some of the adverse effects of the NH4HCO3 on firmness of the vegetables. Ascorbic acid losses were unaffected by either NH4HCO3 treatment.