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Sand bioconsolidation through the precipitation of calcium carbonate by two ureolytic bacteria

Shirakawa, Márcia Aiko; Kaminishikawahara, Katia Kaori; John, Vanderley Moacyr; Kahn, Henrique; Futai, Marcos Massao
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
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66.45%
Two ureolytic strains, B. sphaericus LMG 22257 and Bacillus sp (I-001), were tested for their ability to consolidate sand by submitting them to two days` treatment using 10(7) viable cell concentrations of inocula and medium precipitation with calcium ions. The results showed that B. sphaericus LMG 22257 induced greater calcium carbonate formation. Both strains produced calcite and were able to consolidate sand. Tensile strength of consolidated sand was not a function of the amount of precipitated CaCO(3) but a linear function of the ratio bioconsolidation index (BC) defined as the ratio of CaCO(3) volume to initial sand porosity. A simple model to estimate the engineering benefits of consolidation is proposed. (C) 2011 Elsevier B.V. All rights reserved.

Surface modification of metals by calcium carbonate thin films on a layer-by-layer polyelectrolyte matrix

RAMOS, Ana P.; DORO, Fabio G.; TFOUNI, Elia; GONCALVES, Rogeria R.; ZANIQUELLI, Maria E. D.
Fonte: ELSEVIER SCIENCE SA Publicador: ELSEVIER SCIENCE SA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.59%
A multilayer organic film containing poly(acrylic acid) and chitosan was fabricated on a metallic support by means of the layer-by-layer technique. This film was used as a template for calcium carbonate crystallization and presents two possible binding sites where the nucleation may be initiated, either calcium ions acting as counterions of the polyelectrolyte or those trapped in the template gel network formed by the polyelectrolyte chains. Calcium carbonate formation was carried out by carbon dioxide diffusion, where CO, was generated from ammonium carbonate decomposition. The CaCO3 nanocrystals obtained, formed a dense, homogeneous, and continuous film. Vaterite and calcite CaCO3 crystalline forms were detected. (c) 2007 Elsevier B.V All rights reserved.

Influence of the type of phospholipid head and of the conformation of the polyelectrolyte on the growth of calcium carbonate thin films on LB/LbL matrices

Ramos, Ana Paula; Espimpolo, Daniela Mica; Zaniquelli, Maria Elisabete Darbello
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.68%
Calcium carbonate is one of the most important biominerals, and it is the main constituent of pearls, seashells, and teeth. The in vitro crystallization of calcium carbonate using different organic matrices as templates has been reported. In this work, the growth of calcium carbonate thin films on special organic matrices consisting of layer-by-layer (LbL) polyelectrolyte films deposited on a pre-formed phospholipid Langmuir-Blodgett (LB) film has been studied. Two types of randomly coiled polyelectrolytes have been used: lambda-carrageenan and poly(acrylic acid). A precoating comprised of LB films has been prepared by employing a negatively charged phospholipid, the sodium salt of dimyristoilphosphatidyl acid (DMPA), or a zwitterionic phospholipid, namely dimyristoilphosphatidylethanolamine (DMPE). This approach resulted in the formation of particulate calcium carbonate continuous films with different morphologies, particle sizes, and roughness, as revealed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The crystalline structure of the calcium carbonate particles was analyzed by Raman spectroscopy. The randomly coiled conformation of the polyelectrolytes seems to be the main reason for the formation of continuous films rather than CaCO3 isolated crystals. (C) 2012 Elsevier B.V. All rights reserved.; FAPESP; Fapesp; CNPq; CNPq

Carbon isotope fractionation during calcium carbonate precipitation induced by urease-catalysed hydrolysis of urea

Millo, Christian; Ader, M.; Dupraz, S.; Guyot, F.; Thaler, C.; Foy, E.; Menez, B.
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.51%
Stable carbon isotopic fractionation during calcium carbonate precipitation induced by urease-catalysed hydrolysis of urea was experimentally investigated in artificial water at a constant temperature of 30 degrees C. Carbon isotope fractionation during urea hydrolysis follows a Rayleigh distillation trend characterized by a C-13-enrichment factor of -20 to -22 parts per thousand. CaCO3 precipitate is up to 17.9 parts per thousand C-13-depleted relative to the urea substrate (-48.9 +/- 0.07 parts per thousand). Initial CaCO3 precipitate forms close to isotopic equilibrium with dissolved inorganic carbon. Subsequent precipitation occurs at -2 to -3 parts per thousand offset from isotopic equilibrium, suggesting that the initial delta C-13 value of CaCO3 is reset through dissolution followed by reprecipitation with urease molecules playing a role in offsetting the delta C-13 value of CaCO3 from isotopic equilibrium. Potentially, this isotopic systematics may provide a tool for the diagnosis of ureolytically-formed carbonate cements used as sealing agent. Moreover, it may serve as a basis to develop a carbon isotope tool for the quantification of ureolytically-induced CO2 sequestration. Finally, it suggests carbon isotope disequilibrium as a hallmark of past enzymatic activity in ancient microbial carbonate formation. (C) 2012 Elsevier B.V. All rights reserved.; Centre de Recherches sur le Stockage Geologique du CO; Centre de Recherches sur le Stockage Geologique du CO; ANR (French National Agency for Research); ANR (French National Agency for Research)

"Uma abordagem de parâmetros da biomineralização em um sistema constituído por carbonato de cálcio"; Biomineralization parameters in calcium carbonate system

Paula, Silvia Maria de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 12/05/2006 PT
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66.66%
Conchas do molusco Physa sp., um gastrópode (caracol) comum de aquários de água doce, serviram como modelo para o estudo de alguns aspectos envolvidos na biomineralização. A concha calcária é constituída por cristais de carbonato de cálcio depositados em associação com uma matriz orgânica. Os componentes cristalinos e a matriz, foram estudados por microscopia eletrônica de transmissão e de varredura, e caracterizados por métodos espectroscópicos e analíticos. A constituição cristalina, em geral, assemelha-se àquela existente na maioria dos moluscos, enquanto a camada nacarada, interna da concha, apresenta comparativamente maiores variações. A matriz orgânica consta de um componente insolúvel, essencialmente constituído por polissacarídeos, enxofre e fósforo; e outro componente solúvel, com predominância de serina, glicina, ácido aspártico e ácido glutâmico. A análise feita por ativação de nêutrons demonstrou maior concentração de cálcio, sódio e estrôncio; estes elementos estão geralmente relacionados à presença de aragonita, em outras conchas de moluscos. O estudo qualitativo da fase cristalina foi realizado por difração eletrônica e por espectroscopia de infravermelho. Para análise quantitativa...

Interaction of naproxen with calcium carbonate: physicochemical characterization and in vitro drug release studies

Paroha,Shweta; Dubey,Ravindra Dhar; Mallick,Subrata
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
Relevância na Pesquisa
66.68%
Interaction and physicochemical characterization of dispersions of naproxen in calcium carbonate after freeze-drying the wet-state equilibrated mixture have been investigated by analytical methods. The FT-IR study revealed the acid-base reaction between naproxen and calcium carbonate. The DSC study indicated physical interaction and significantly diminished crystallinity of naproxen in the formulation containing higher quantities of calcium carbonate. Furthermore, the SEM study showed the reduced particle size and loss of crystalline morphology in the same sample. Drug release increased with the increase of calcium carbonate in the formulations. Formulation of naproxen with calcium carbonate in 1:2 ratio allowed its dissolution to the greatest extent (94.96%) while other compositions, 1:0.5 and 1:1, showed 80.86% and 78.30% release, respectively.

Calcium carbonate mediates higher lignin peroxidase activity in the culture supernatant of Streptomyces Viridosporus T7A

MACEDO,J. M. B.; GOTTSCHALK,L. M. F.; BON,E. P. S.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/1999 EN
Relevância na Pesquisa
66.51%
Lignin peroxidase (LiP) production has been extensively studied due to the potential use of this enzyme in environmental pollution control. Important aspects of the production of the enzyme by S. viridosporus T7A which have been studied include the improvement of yield and enzyme stabilization. In experiments performed in agitated flasks containing culture media composed of yeast extract as the source of nitrogen, mineral salts and different carbon sources, the use of glucose resulted in the highest values for LiP activity (350 U/L), specific LiP activity (450 U/g) and productivity (7 U/L/h). As the profile obtained with glucose-containing medium suggested enzyme instability, the effect of calcium carbonate was evaluated. The addition of CaCO3 in two different concentrations, 0.5% and 5.0%, resulted in higher values of maximum LiP activity, 600 and 900 U/L, respectively. The presence of this salt also anticipated enzyme activity peaks and allowed the detection of higher enzyme activities in the extracellular medium for longer periods of time. These results indicate a positive effect of calcium carbonate on LiP production, which is extremely relevant for industrial processes.

Mechanical properties of polypropylene/calcium carbonate nanocomposites

Eiras,Daniel; Pessan,Luiz Antonio
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
Relevância na Pesquisa
66.59%
The aim of this work was to study the influence of calcium carbonate nanoparticles in both tensile and impact mechanical properties of a polypropylene homopolymer. Four compositions of PP/CaCO3 nanocomposites were prepared in a co-rotational twin screw extruder machine with calcium carbonate content of 3, 5, 7 and 10 wt. (%) The tests included SEM analyzes together with EDS analyzer and FTIR spectroscopy for calcium carbonate, tensile and impact tests for PP and the nanocomposites. The results showed an increase in PP elastic modulus and a little increase in yield stress. Brittle-to-ductile transition temperature was reduced and the impact resistance increased with the addition of nanoparticles. From the stress-strain curves we determined the occurrence of debonding process before yielding leading to stress softening. Debonding stress was determined from stress-strain curves corresponding to stress in 1% strain. We concluded that the tensile properties depend on the surface contact area of nanoparticles and on their dispersion. Finally we believe that the toughening was due to the formation of diffuse shear because of debonding process.

Influence of calcium carbonate nanoparticles on the crystallization of olypropylene

Eiras,Daniel; Pessan,Luiz Antonio
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
Relevância na Pesquisa
66.64%
The aim of this work was to study the influence of calcium carbonate nanoparticles in crystallization process of polypropylene. Four compositions of PP/CaCO3 nanocomposites were prepared in a co-rotational twin screw extruder machine with calcium carbonate content of 3, 5, 7 and 10 wt. (%). The tests included SEM analyzes for calcium carbonate, differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) for the nanocomposites. The results showed an increase in PP crystallization temperature and crystallinity degree, and a reduction in spherullites size. The formation of PP β phase was confirmed by DSC and WAXD results. Finally from DSC analyses under isothermal conditions it was confirmed that calcium carbonate nanoparticles have a nucleation effect in polypropylene crystallization process by reducing the half crystallization time and increasing the kinetic constant (k).

Development and characterization of a novel bioresorbable and bioactive biomaterial based on polyvinyl acetate, calcium carbonate and coralline hydroxyapatite

Aragón,Javier; González,Ramón; Fuentes,Gastón; Palin,Luca; Croce,Gianluca; Viterbo,Davide
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2011 EN
Relevância na Pesquisa
66.4%
Coralina® HAP-200 (coralline hydroxyapatite obtained by hydrothermal treatment of marine corals) and POVIAC® (polymeric matrix based on PVAc), commercial trade marks were mixed with a natural product from the Cuban sea costs, i.e. calcium carbonate from Porites Porites coral, to obtain a novel bioactive composite with potential use as bone restoration material. The samples were characterized by physical-chemical (FTIR, XRD, SEM, EDS) and mechanical studies. It was shown that there is no chemical interaction between the inorganic filler and the polymer matrix, each conserving the original properties of the raw materials. The studied formulation had a compressive strength similar to that reported for trabecular bone. Scanning electron microscopy examination revealed that the addition of CaCO3 induces a change on the morphologic structure of the composite obtained after 30 days of SBF immersion. These composites generate novel biomaterials capable of promoting the deposition of a new phase, a Ca-P layer due to the bioactivity of a Ca2+ precursors.

Characterization of calcium carbonate obtained from oyster and mussel shells and incorporation in polypropylene

Hamester,Michele Regina Rosa; Balzer,Palova Santos; Becker,Daniela
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2012 EN
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66.59%
There is a high content of calcium carbonate in mussel and oyster shells, which can be used in the formulation of medicine, in construction or as filler in polymer materials. This work has as its main objective to obtain calcium carbonate from mussel and oyster shells and used as filler in polypropylene compared their properties with polypropylene and commercial calcium carbonate composites. The shellfish was milling and heated at 500 ºC for 2 hours. The powder obtained from shellfish were characterized by scanning electron microscopy (SEM), X-ray fluorescence, particle size distribution and abrasiveness and compared with commercial CaCO3 and mixed with polypropylene. The thermal and mechanical properties of polypropylene with CaCO3 obtained from oyster and mussel shells and with commercial CaCO3 were analysed. The results showed that CaCO3­ can be obtained from oyster and mussel shell and is technically possible to replace the commercial CaCO3 for that obtained from the shells of shellfish in polypropylene composites.

Effect of gastric acid suppression with pantoprazole on the efficacy of calcium carbonate as a phosphate binder in haemodialysis patients

Cervelli, M.; Shaman, A.; Meade, A.; Carroll, R.; McDonald, S.
Fonte: Blackwell Publishing Asia Publicador: Blackwell Publishing Asia
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
66.56%
AIM:   Metallic phosphate binders require acidity to dissociate to the free metallic ion and bind phosphorus. Altered gastric acidity may, therefore, influence phosphate-binding efficacy. We evaluated the clinical effect of pantoprazole on the efficacy of calcium carbonate phosphate binders in haemodialysis patients. METHODS:   The study had two parts: a cross-sectional study (n = 67), and an interventional, crossover, double-blind, randomized, placebo-controlled trial in 26 patients given pantoprazole 40 mg daily or placebo for two consecutive 6-week periods. RESULTS:   The cross-sectional study showed no difference between those on and off acid suppressants in phosphate (1.43 ± 0.45 vs 1.46 ± 0.31 mmol/L, P = 0.782) or other parameters except age (72.2 ± 9.8 vs 63.8 ± 14.8 years, P = 0.01). In the interventional study, phosphate was higher during pantoprazole than placebo (1.59 ± 0.3 vs 1.42 ± 0.3 mmol/L, P = 0.005). Serum calcium (2.37 ± 0.2 vs 2.46 ± 0.2 mmol/L, P = 0.012) and ionized calcium (1.17 ± 0.1 vs 1.22 ± 0.1 mmol/L, P = 0.013) were lower during pantoprazole treatment. CaxPO(4) (3.76 ± 0.7 vs 3.48 ± 0.7 mmol(2) /L(2) ...

Effect of calcium (II) and iron (II) on the precipitation of calcium carbonate and iron carbonate solid solutions and on scale inhibitors retention

Alsaiari, Hamad Amer
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
66.78%
Mineral scale formation is important to many areas of science and engineering, from drinking water treatment to oceanography to oil and gas production. In some cases mineral deposition is beneficial, as in water treatment for heavy metal or arsenic removal, and sometimes it is deleterious, as occurs in oil and gas production due to co-produced water. In either case, understanding the mechanisms of precipitation and inhibition is critical. Work in this thesis has focused on the impact of metal ions on mineral scale formation, and control. The results reveal that the addition of metal ions in the pill solution significantly improved the retention of scale inhibitors. Both BHPMP and DTPMP returns were significantly extended by the addition of Ca 2+ and Fe 2+ Also trace levels of Zn 2+ significantly enhanced the performance and retention of both BHPMP and DTPMP. The enhanced scale inhibition may be caused by a complex of metal ions with amine group of polyamino- polyphosphonates. It is known that the effectiveness of inhibitors varies upon the type of scale formed where it has been mentioned in the literature that common calcium carbonate inhibitors are not effective for preventing iron carbonate. Therefore, this work was also intended to investigate the impact of calcium and iron ions in the co-precipitation of iron-calcium carbonate solid solutions (Fe x Ca 1-x CO 3 ). Three different experimental methods were applied to investigate and predict the precipitation of Fe x Ca 1-x CO 3 : Free drift...

Consolidation of degraded ornamental porous limestone stone by calcium carbonate precipitation induced by the microbiota inhabiting the stone

Jim??nez-L??pez, Concepci??n; Rodr??guez-Navarro, Carlos; Pi??ar, Guadalupe; Carrillo-Ros??a, Javier; Rodr??guez Gallego, Manuel; Gonz??lez-Mu??oz, Teresa
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.51%
El art??culo original ha sido publicado por Chemosphere, de la Editorial Elsevier, disponible en: http://www.elsevier.com/wps/find/journaldescription.cws_home/362/description#description http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V74-4NF2NCX-1&_user=654849&_coverDate=08%2F31%2F2007&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_acct=C000035398&_version=1&_urlVersion=0&_userid=654849&md5=a44718f997b5057999cd6a5f100b7289&searchtype=a; Although it has already been shown that calcareous stone can be consolidated by using a bacterially-inoculated culture media, a more user-friendly method is the in situ application of a sterile culture media that is able to activate, among the microbial community of the stone, those bacteria with a potential for calcium carbonate precipitation. In order to test this new method for stone consolidation, non-sterilized decayed porous limestone was immersed in sterile nutritional media. Results were compared to those of the runs in which stone sterilized prior to the treatment was used. The effects of the microbial community on stone consolidation were determined by recording the evolution of the culture media chemistry. The treated stones were tested for mechanical resistance and porosity. Results demonstrate that the tested media were able to activate bacteria from the microbial community of the stone. As a consequence of the growth of these bacteria...

Bioprecipitation of Calcium Carbonate Crystals by Bacteria Isolated from Saline Environments Grown in Culture Media Amended with Seawater and Real Brine

Silva-Castro, Gloria Andrea; Uad, Imane; Gonz??lez-Mart??nez, A.; Rivadeneyra, Almudena; Gonz??lez L??pez, Jes??s; Rivadeneyra, Mar??a Angustias
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.68%
The precipitation of calcium carbonate and calcium sulphate by isolated bacteria from seawater and real brine obtained in a desalination plant growth in culture media containing seawater and brine as mineral sources has been studied. However, only bioprecipitation was detected when the bacteria were grown in media with added organic matter. Biomineralization process started rapidly, crystal formation taking place in the beginning a few days after inoculation of media; roughly 90% of total cultivated bacteria showed. Six major colonies with carbonate precipitation capacity dominated bacterial community structure cultivated in heterotrophic platable bacteria medium. Taxonomic identification of these six strains through partial 16S rRNA gene sequences showed their affiliation with Gram-positive Bacillus and Virgibacillus genera. These strains were able to form calcium carbonate minerals, which precipitated as calcite and aragonite crystals and showed bacterial fingerprints or bacteria calcification. Also, carbonic anhydrase activity was observed in three of these isolated bacteria. The results of this research suggest that microbiota isolated from sea water and brine is capable of precipitation of carbonate biominerals, which can occur in situ with mediation of organic matter concentrations. Moreover...

Suppression of parathyroid hormone and bone resorption by calcium carbonate and calcium citrate in postmenopausal women

Thomas, S.; Need, A.; Tucker, G.; Slobodian, P.; O'Loughlin, P.; Nordin, B.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
66.8%
This study was conducted to compare the suppressive effects of calcium carbonate and calcium citrate on bone resorption in early postmenopause. Calcium citrate is thought to be better absorbed. We therefore tested the hypothesis that calcium as citrate is more effective than calcium as carbonate in suppressing parathyroid hormone (PTH) and C-terminal telopeptide. Twenty-five healthy postmenopausal women were recruited in this double blind crossover study. The subjects were randomly allocated to receive either 1,000 mg of elemental calcium as carbonate or 500 mg of calcium as citrate. They were given the alternate calcium dose 1 week later. Serum measurements of total and ionized calcium, phosphate, PTH, and CrossLaps were repeated 12 hours after each dose. Analysis of variance found no significant difference between measures for the two salts. Tests for equivalence indicated that 500 mg of calcium citrate may be superior to 1,000 mg of calcium carbonate in raising serum total and ionized calcium (P = 0.04 and 0.05, respectively). For all parameters measured, 500 mg of calcium citrate was at least as beneficial as 1,000 mg of calcium carbonate. Calcium citrate is at least as effective as calcium carbonate in suppressing PTH and C-terminal telopeptide cross-links...

Calcium acetate versus calcium carbonate in the control of hyperphosphatemia in hemodialysis patients

d'Almeida Filho,Eufrônio José; Cruz,Elisa de Albuquerque Sampaio da; Hoette,Marcos; Ruzany,Frederico; Keen,Luana Neves Lopes; Lugon,Jocemir Ronaldo
Fonte: Associação Paulista de Medicina - APM Publicador: Associação Paulista de Medicina - APM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2000 EN
Relevância na Pesquisa
66.75%
CONTEXT: Hyperphosphatemia has an important role in the development of bone and mineral abnormalities in end-stage renal disease (ESRD). OBJECTIVE: To compare the phosphorus binding power and the hypercalcemic effect of calcium acetate and calcium carbonate in hemodialysis patients. TYPE OF STUDY: Crossover, randomized, double-blind study. PLACE: A private hospital dialysis center. PARTICIPANTS: Fifty-two patients who were undergoing regular hemodialysis three times a week ([Ca++] dialysate = 3.5 mEq/L). PROCEDURES: Half of the patients were started on 5.6 g/day of calcium acetate and, after a 2 week washout period, received 6.2 g/day of calcium carbonate. The other half followed an inverse protocol. MAIN MEASUREMENTS: Clinical interviews were conducted 3 times a week to monitor for side effects. Determinations of serum urea, calcium, phosphorus, hematocrit, Kt/V and blood gas analysis were obtained before and after each treatment. RESULTS: Twenty-three patients completed the study. A significant increase in calcium plasma levels was only observed after treatment with calcium carbonate [9.34 mg/dl (SD 0.91) vs. 9.91 mg/dl (SD 0.79), P < 0.01]. The drop in phosphorus levels was substantial and significant for both salts [5.64 mg/dl (SD 1.54) vs. 4.60 mg/dl (SD 1.32)...

Stress development during drying of calcium carbonate suspensions containing carboxymethylcellulose and latex particles

Wedin, Par; Martinez, Carlos J; Lewis , Jennifer A; Daicic , John; Bergstrom , Lennart
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
66.54%
Stress development during drying of coatings produced from aqueous dispersions of calcium carbonate particles in the presence and absence of organic binders was studied using a controlled-environment stress apparatus that simultaneously monitored drying s

The effect of soluble organic additives on the stress development during drying of calcium carbonate suspensions

Wedin, Par; Lewis , Jennifer A; Bergstrom , Lennart
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
66.45%
The effect of polymer, plasticizer, and surfactant additives on stress development during drying of calcium carbonate particulate coatings was studied using a controlled-environment apparatus that simultaneously monitors drying stress, weight loss, and re

Preparation of ultra-fine calcium carbonate by a solvent-free reaction using supersonic airflow and low temperatures

Cai,Yan-Hua; Ma,Dong-Mei; Peng,Ru-Fang; Chu,Shi-Jin
Fonte: South African Journal of Chemistry Publicador: South African Journal of Chemistry
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
Relevância na Pesquisa
66.51%
The treatment of calcium chloride with sodium carbonate under solvent-free conditions with a supersonic airflow and at a low heating temperature leads to the synthesis of ultra-fine calcium carbonate. The reaction not only involves mild conditions, a simple operation, and high yields but also gives a high conversion rate.