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Catalytic Calcination of Calcium Carbonate

Description: The calcination of calcium carbonate in a cement or a lime kiln uses approximately two to four times the theoretical quantity of energy predicted from thermodynamic calculation depending upon the type of the kiln used (1.4 x 10^6 Btu/ton theoretical to 6 x 10^6 Btu/ton actual). The objective of this research was to attempt to reduce the energy required for the calcination by 1. decreasing the calcination temperature of calcium carbonate, and/or 2. increasing the rate of calcination at a specific temperature. Assuming a catalytic enhancement of 20 percent in the industrial applications, an energy savings of 300 million dollars annually in the United States could be reached in the cement and lime industries. Three classes of compounds to date have shown a positive catalytic effect on the calcination of calcium carbonate. These include alkali halides, phospho- and silico-molybdate complexes, and the fused carbonates system.
Date: August 1985
Creator: Safa, Ali Ibrahim, 1953-
Partner: UNT Libraries

Response of Freshwater and Saltwater Toxicity Test Species to Calcium and Salinity Concentrations Encountered in Toxicity Tests

Description: The responses of freshwater (Daphnia magna. Pimephales promelas) and saltwater (Mysidopsis bahia. Cyprinodon variegatus) toxicity test species to elevated calcium concentrations and changing salinity conditions were investigated. The use of salinity as a criterion for selection between saltwater and freshwater test species was investigated by conducting both calcium and salinity toxicity tests. Salinity was determined to be an inappropriate criterion under conditions encountered in this study.
Date: 1989
Creator: Price, Edmund E., 1954-
Partner: UNT Libraries

Final technical report for contract year November 9, 1947 to November 9, 1948

Description: Report describing processes to prepare metallic calcium of a very high purity. Report details promising methods for electrolyte purification. Methods of chemical analysis for nitrogen are also improved upon and spectrochemical methods and standards established for twelve other specified elements.
Date: 1948
Creator: Brown, H. & Woodberry, P.
Partner: UNT Libraries Government Documents Department

Effect of Calcium Channel Antagonists and Other Agents on Olfactory Reception

Description: The role of Ca++ in olfactory responses was investigated with inorganic and organic calcium channel antagonists. Electrophysiological responses to odorants were recorded from frog olfactory mucosa before and after aerosol application of different agents. Electroolfactogram responses were blocked by certain inorganic ions with the order of effectiveness Zn++ >Ln+++>Cd++>Ca++>Co++>Sr++>Mg++. Ba++ potentiated olfactory responses, and is known to potentiate calcium channel-mediated responses in other tissues. Certain local anesthetics which are thought to act through calcium channel blockade were inhibitory to olfactory responses, with the order of effectiveness being dibucaine>tetracaine>procaine. These data support the idea that Ca++ is involved in olfaction, perhaps acting as a current carrier and/or a second messenger. Preliminary experiments on channel localization were performed using a silicon-labeled amine. Attempts to localize the silicon label were inconclusive, although silicon was detected in the olfactory tissue.
Date: August 1985
Creator: Rosick, Edward R. (Edward Rudolph)
Partner: UNT Libraries

Calcium Silicates: Glass Content and Hydration Behavior

Description: Pure, MgO doped and B2C3 doped monocalcium, dicalcium, and tricalcium silicates were prepared with different glass contents. Characterization of the anhydrous materials was carried out using optical microscopy, infrared absorption spectroscopy, and X-ray powder diffraction. The hydration of these compounds was studied as a function of the glass contents. The hydration studies were conducted at 25°C. Water/solid ratios of 0.5, 1, 10, and 16 were used for the various experiments. The hydration behavior was monitored through calorimetry, conductometry, pH measurements, morphological developments by scanning electron microscopy, phase development by X-ray powder diffraction, and percent combined water by thermogravimetry. A highly sensitive ten cell pseudo-adiabatic microcalorimeter was designed and constructed for early hydration studies. Conductometry was found to be of great utility in monitoring the hydration of monocalcium silicate and the borate doped dicalcium silicates.
Date: August 1987
Creator: Zgambo, Thomas P. (Thomas Patrick)
Partner: UNT Libraries


Description: In reduction reactions of CeO/sub 2/, with calcium and a CaCl/sub 2/ flux, the use of vibrational energy was shown to have a marked effect on the yield of coalesced metal. Buttons of 40 to 50% theoretical yield were obtained from the vibrated reductions. As the flux concentration is decreased, the slag becomes more viscous containing undissolved CaO. The undissolved CaO present prevents the metal from completely coalescing, but the metal can be recovered from the slag and coalesced under CaCl/sub 2/ containing a small amount of calcium to reduce any oxide skin present. Cerium pellet yields of 50 to 60% metal were obtained by the procedure and were not difficult to handle in air. Cerium was used as a stand-in material for plutonium. (B.O.G.)
Date: February 13, 1956
Creator: Tolley, W. B.
Partner: UNT Libraries Government Documents Department

Calcium Aluminates Synthesis, Characterization, and Hydration Behavior

Description: The hydration behavior of the calcium aluminates as a function of the glass content, the curing temperature, and the water-solid ratio was investigated. In order to keep them from influencing the results, the free-lime content and the surface area of all samples were kept constant, whenever possible. Samples were hydrated with a water-solid ratio of 10/1 for periods of 1 to 90 days. Three curing temperatures were studied; 2°C, 25°C, and 50°C. Samples were hydrated in tightly sealed polyethylene containers to prevent reactions with atmospheric carbon dioxide. The hydration was followed by X-ray diffraction and thermal analysis. Only two samples, Hexacalcium Tetra-alumino Magnesium Silicate and Tricalcium Magnesium Dialuminate, were successfully prepared in an amorphous form. These compounds were used to investigate the effect of glass content on the hydration behavior. Results indicate that when the glass content is increased a corresponding increase is found in the percent combined water. Samples hydrated at 25°C were influenced by changes in the glass content to a greater degree than were those hydrated at either 2°C or 50°C. The effect of the water-solid ratio on the hydration behavior of the calcium aluminates was studied using the compounds; Hexacalcium Tetra-Alumino Magnesium Silicate/ and Dodecacalcium Hepta-Aluminate. In general, samples that were hydrated with large water-solid ratios reacted more completely than did those hydrated with small water-solid ratios. The presence of sufficient water to theoretically hydrate the samples to completion did not guarantee that the sample would do so. The curing temperature influenced the hydration behavior to a greater degree than did the glass content or the water-solid ratio. Increasing the curing temperature not only increased the rate of hydration, but, in some cases, also changed the hydration products.
Date: December 1984
Creator: Griffin, Joseph George
Partner: UNT Libraries

New Manufacturing Method for Paper Filler and Fiber Material

Description: The use of fillers in printing and writing papers has become a prerequisite for competing in a global market to reduce the cost of materials. Use of calcium carbonates (ranging from 18% to 30%) as filler is a common practice in the paper industry but the choices of fillers for each type of papers vary widely according to its use. The market for uncoated digital printing paper is one that continues to introduce exciting growth projections and it is important to understand the effect that different types of calcium carbonates have on the paper properties made of 100% eucalyptus pulp. The current study is focused on selecting the most suitable market available calcium carbonate for the production of uncoated Eucalyptus digital printing paper, targeting a potential filler increase of 5% above the currently used filler content. We made hand sheets using 13 different varieties of widely used calcium carbonates [Nine samples of PCC (two rhombic and seven scalenohedral, covering a wide particle size range from 1.2 {micro}m to 2.9 {micro}m), and four samples of GCC (three anionic and one cationic, with a particle size range from 0.7 {micro}m to 1.5 {micro}m)] available in the market followed by a 12” pilot plant paper machine run. The detailed analysis on the main structural, optical and strength properties of the hand sheets found that the most suitable calcium carbonate for uncoated Eucalyptus digital printing paper production is scalenohedral PCC, with a particle size of 1.9 {micro}m for its positive effects on thickness, stiffness, brightness and opacity of paper.
Date: June 26, 2011
Creator: Doelle, Klaus
Partner: UNT Libraries Government Documents Department

Calcium/metal Sulfide Battery Development Program. Progress Report, October 1979 - September 1980

Description: A Ca-Al-Si/FeS2 cell has been developed and has exhibited reasonably stable capacity through 3200 h of operation. This system is expected to be capable of meeting the ultimate performance goals (i.e., 160 W.h/kg) of this development program. Further tests of this cell system in the coming year will better define its ultimate performance capabilities.
Date: March 1981
Creator: Barney, Duane L.; Roche, M. F.; Preto, S. K.; Ross, L. E.; Otto, N. C. & Martino, F. J.
Partner: UNT Libraries Government Documents Department

Recovery of lime from coal gasifier waste containing calcium sulfide

Description: Calcium-based materials hold great promise as sorbents for reduced sulfur compounds at high temperature. Such materials are needed for hot gas clean up or for direct addition to coal gasifiers in several types of integrated coal gasification, combined-cycle (IGCC) power generation systems under development. However, their use has been hindered by the lack of a suitable regeneration process for converting CaS back to CaO. Recently, it was discovered in the laboratory that CaS particles can be converted rapidly and almost completely to CaO by a cyclic process which exposures the material alternately and repeatedly to oxidation and reduction at 900 to 1,100 C. During oxidation with air a small portion of CaS is converted to CaSO{sub 4} which upon treatment with a reducing gas is converted to CaO. By repeating the cycle numerous times, individual particles are converted completely to CaO. Such a process can be carried out in a fluidized bed reactor which either has both oxidizing and reducing zones or is supplied with gas that is alternately oxidizing and reducing. The cyclic oxidation/reduction process for converting CaS to CaO has been demonstrated with a thermogravimetric analysis (TGA) systems, and the results are reported below. The effects of temperature and gas composition on the overall rate of conversion are indicated as well as the effect of subjecting typical sorbent materials to repeated sulfidation and regeneration.
Date: October 1, 1995
Creator: Jagtap, S.B. & Wheelock, T.D.
Partner: UNT Libraries Government Documents Department

The Analysis of TBP Process Streams for Calcium with the Flame Photometer

Description: Summary: A method was found for determining calcium concentrations in TBP process streams in spite of serious interferences bysodium, ferrous, uranyl, sulfate, phosphate, and sulfamate ions as well as by TBP. The precision attainable varied from sample to sample, depending upon its composition. In general, errors of 20% or greater occurred. The smallest determinable amount of calcium was about 10 mg/1.
Date: February 20, 1953
Creator: Brite, D. W.
Partner: UNT Libraries Government Documents Department

Biomimetic Nanocomposites of Calcium Phosphate and Self-Assembling Triblock and Pentablock Copolymers

Description: In an effort to mimic the growth of natural bone, self-assembling, micelle and gel-forming copolymers were used as a template for calcium phosphate precipitation. Because of the cationic characteristics imparted by PDEAEM end group additions to commercially available Pluronic{reg_sign} Fl27, a direct ionic attraction mechanism was utilized and a polymer-brushite nanocomposite spheres were produced. Brushite coated spherical micelles with diameters of {approx}40 nm, and agglomerates of these particles (on the order of 0.5 {mu}m) were obtained. Thickness and durability of the calcium phosphate coating, and the extent of agglomeration were studied. The coating has been shown to be robust enough to retain its integrity even below polymer critical micelle concentration and/or temperature. Calcium phosphate-polymer gel nanocomposites were also prepared. Gel samples appeared as a single phase network of agglomerated spherical micelles, and had a final calcium phosphate concentration of up to 15 wt%. Analysis with x-ray diffraction and NMR indicated a disordered brushite phase with the phosphate groups linking inorganic phase to the polymer.
Date: August 9, 2006
Creator: Enlow, Drew Lenzen
Partner: UNT Libraries Government Documents Department

Final report for grant number DE-FG02-06ER64244 to the University of Idaho (RW Smith)-coupling between flow and precipitation in heterogeneous subsurface environments and effects on contaminant fate and transport

Description: Engineered remediation strategies for inducing mineral precipitation in the subsurface typically involve the introduction of at least one reactant either by direct injection or by in situ generation. The localization of reactant sources means a wide range of saturation states and ion ratios will be created as reactants are mixed: These conditions together can result in a wide range of precipitation rates, as well as impact which mineral phase precipitates. This is potentially important for the capacity of the precipitates to take up of trace metal contaminants, for their long term stability. Aragonite, for example, is able to sequester a larger amount of Sr than calcite. However, aragonite is less stable under typical groundwater conditions, and so may release sequestered Sr over time as the aragonite transforms to a more stable phase. In addition, previous experimental studies have indicated that other system constituents may influence calcium carbonate precipitation and consequently the Sr uptake potential of a system. For example, dissolved organic carbon (at levels typical of groundwaters) can suppress crystal growth. As a result, the continuous nucleation of small crystals, rather than growth of existing crystals, may be the dominant mode of precipitation. This has the potential for greater uptake of Sr because the smaller crystal sizes associated with nucleated calcite may more readily accommodate the distortion resulting from substitution of the larger Sr ion for Ca ions than can larger crystals. However, these smaller crystals may also be less stable and over the long term release Sr as a result of Ostwald ripening. To better understand the formation and composition of relevant calcium carbonate mineral phases two related series of mineral precipitation experiments were conducted. The first series of experiments, conducted using a Continuously Stirred Tank Reactor (CSTR) operated at steady state rates of precipitation was focused on understanding ...
Date: June 18, 2010
Creator: Smith, Robert W.; Beig, Mikala S.; Gebrehiwet, Tsigabu; Corriveau, Catherine E.; Redden, George & Fujita, Yoshiko
Partner: UNT Libraries Government Documents Department

Role of Calcium and Phospholipids in Transepithelial Sodium Ion and Water Transport in Amphibian Epithelia

Description: The present investigation is concerned with determining the role of calcium, phospholipids, and phospholipid metabolites on transepithelial sodium and water transport in response to antidiuretic hormone (ADH). These studies utilize the frog skin for determining sodium transport and amphibian urinary bladder for water flow measurements and scanning electron microscopy of cell surface morphology. The results demonstrate that phospholipids and phospholipid metabolites containing arachidonic acid stimulate transepithelial sodium transport through amiloride sensitive channels and the action of these lipids involves the synthesis of prostaglandins. These lipids also inhibited the increase in water flow induced by ADH, and this effect was prevented with prostaglandin synthesis inhibitors. Prostaglandins alter intracellular calcium concentrations and agents effecting calcium metabolism alter cell surface morphology and the changes in surface substructure induced by ADH. These observations support the hypothesis that alterations in membrane permeability to water and ions may involve metabolism of membrane phospholipids and prostaglandin biosynthesis.
Date: August 1983
Creator: Tarapoom, Nimman
Partner: UNT Libraries

Analysis of the Trypanosoma brucei Genome and Identification and Characterization of a Gene Family Encoding Putative EF-Hand Calcium-Binding Proteins

Description: The flagellum of Trypanosoma brucei contains a family of antigenically related EF-hand calcium-binding proteins which are called the calflagins. Genomic Southern blots indicated that multiple copies of calflagin genes occur in T brucei. All of the copies were contained in a single 23 kb Xhol-Xhol fragment. Genomic fragments of 2.5 and 1.7 kb were cloned that encoded calflagin sequences. Two new members of the calflagin family were found from genomic clone sequences. The deduced amino acid sequences of the genomic clones showed the calflagin genes were arranged tandemly along the genomic fragments and were similar to previously described calflagins. The calflagin genes were related by two unrelated 3' flanking sequences. An open reading frame that was unrelated to any calflagin was found at the 5' end of the 2.5 kb genomic fragment. Each encoded protein (~24,000u) contained three EF-hand calcium-binding motifs and one degenerate EF-hand motif. In general, variability among the T. brucei calflagins is greater than related proteins in T. lewisii and T. cruzi. This variability results from amino acid substitutions at the amino and carboxy termini, and duplication of internal segments.
Date: May 1998
Creator: DeFord, James H. (James Henry), 1956-
Partner: UNT Libraries

Roles of Calcium Ions and Cyclic AMP in Olfactory Transduction

Description: The roles of Ca2 + and cAMP in olfactory transduction were explored using agents which affect calcium channels and second messenger systems. These agents were applied at certain calculated final concentrations onto olfactory epithelia of urethane-anesthetized frogs (Sana PiPlens) by two-sec aerosol spray. During extracellular recording, saturated vapors of isoamyl acetate were delivered every 100 sec in 0.3 sec pulses to produce an electroolfactogram (EOG). Inorganic cations that block inward calcium currents inhibit EOG responses with the following rank order: (La3+) > (Zn2+, Cd2+) > (Al3+, Ca2+, Sr2+) > (Co2+). Application of 7.5 mM La3+ eradicates £0G's, while Ba2+ (which can carry more current that Ca2+) initially produces significant enhancement (F=43.04, p<0.001, df=19). Magnesium ion has no effect on EOG's at 7.5 mM, while 1.5 X 10"4M Ca2+ is significantly inhibitory (F=5.74; p=0.0355; df=12). Control aerosol sprays of distilled water depress EOG's by an average of 5%. The organic calcium channel antagonists diltiazem and verapamil inhibit EOG's by 17% and 36X, respectively, at a concentration of 1.5 X 10~*M. Verapamil produces significant inhibition (F=17.17; p=0.002; df=ll) at 1.5 X 10" 5 M, while the 1,4-dihydropyridine calcium channel antagonists, nicardipine and nifedipine, do not inhibit beyond 1% DMSO controls. Several calmodulin antagonists decrease EOG's, but without correlation to their anti-calmodulin potency. Application of 1.5 X 10"*M chlorpromazine and N-(6-aminohexyl)-5-chloro-l-naphthalenesulfonamide inhibit EOG's by 31% and 27%, respectively, while trifluoperazine inhibits by 23%. Dibutyryl cAMP, a lipophilic mimic of cAMP, produces 54% inhibition at 1.5 X 10" *M. Dibutyryl cGMP, cGMP, cAMP, and adenosine all decrease EOG's by less than 15% compared to distilled water controls. Forskolin, a reversible activator of adenylate cyclase, inhibits EOG's by 57% at 1.5 X 10"5M, which is significant beyond the 1% DMSO controls (F=17.17; p=0.002; df=ll). These data support the hypothesis that Ca2+ participates in olfactory transduction. ...
Date: December 1986
Creator: Winegar, Bruce D. (Bruce David)
Partner: UNT Libraries

Secretory pathway Ca2+/Mn2+-ATPase isoform 2 and lactation: specific localization of plasmalemmal and secretory pathway Ca2+ pump isoforms in the mammary gland

Description: The supply of calcium to the developing neonate via milk is an important physiological process. Until recently the mechanism for the enrichment of milk with calcium was thought to be almost entirely mediated via the secretory pathway. However, recent studies suggest that a specific isoform of the plasma membrane calcium ATPase, PMCA2, is the primary mechanism for calcium transport into milk, highlighting a major role for apical calcium transport. We compared the expression of the recently identified secretory calcium ATPase, SPCA2, and SPCA1, in the mouse mammary gland during different stages of development. SPCA2 levels increased over 35 fold during lactation, while SPCA1 increased only a modest two fold. The potential importance of SPCA2 in lactation was also highlighted by its localization to luminal secretory cells of the mammary gland during lactation, while SPCA1 was expressed throughout the cells of the mammary gland. We also observed major differences in the localization of PMCA2 and PMCA1 during lactation. Using the SCp2 mouse mammary epithelial cell 3D culture model, differences in the sub-cellular distribution of PMCA2 and PMCA1 were clear. These studies highlight the likely specific roles of PMCA2 and SPCA2 in lactation, and link the recently characterized SPCA2 calcium pump to the supply of calcium into milk and the regulation of Golgi resident enzymes important in lactation. They also indicate that calcium transport into milk is a complex interplay between apical and secretory pathways.
Date: April 9, 2008
Creator: Faddy, Helen M.; Smart, Chanel E.; Xu, Ren; Lee, Genee Y.; Kenny, Paraic A.; Feng, Mingye et al.
Partner: UNT Libraries Government Documents Department

Enhanced Hydrogen Production Integrated with CO2 Separation in a Single-Stage Reactor

Description: Hydrogen production from coal gasification can be enhanced by driving the equilibrium limited Water Gas Shift reaction forward by incessantly removing the CO{sub 2} by-product via the carbonation of calcium oxide. This project aims at using the OSU patented high-reactivity mesoporous precipitated calcium carbonate sorbent for removing the CO{sub 2} product. Preliminary experiments demonstrate the show the superior performance of the PCC sorbent over other naturally occurring calcium sorbents. Gas composition analyses show the formation of 100% pure hydrogen. Novel calcination techniques could lead to smaller reactor footprint and single-stage reactors that can achieve maximum theoretical H{sub 2} production for multicyclic applications. Sub-atmospheric calcination studies reveal the effect of vacuum level, diluent gas flow rate, thermal properties of the diluent gas and the sorbent loading on the calcination kinetics which play an important role on the sorbent morphology. Steam, which can be easily separated from CO{sub 2}, is envisioned to be a potential diluent gas due to its enhanced thermal properties. Steam calcination studies at 700-850 C reveal improved sorbent morphology over regular nitrogen calcination. A mixture of 80% steam and 20% CO{sub 2} at ambient pressure was used to calcine the spent sorbent at 820 C thus lowering the calcination temperature. Regeneration of calcium sulfide to calcium carbonate was achieved by carbonating the calcium sulfide slurry by bubbling CO{sub 2} gas at room temperature.
Date: September 30, 2005
Creator: Iyer, Mahesh; Gupta, Himanshu; Wong, Danny & Fan, Liang-Shih
Partner: UNT Libraries Government Documents Department