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Calcium Salts (calcium + salt)
Selected AbstractsCombination of a hydroxy-functional organophosphorus oligomer and a multifunctional carboxylic acid as a flame retardant finishing system for cotton: Part II.FIRE AND MATERIALS, Issue 5 2003Formation of calcium salt during laundering Abstract Multifunctional carboxylic acids, such as 1,2,3,4-butanetetracarboxylic acid (BTCA), were used to bond a hydroxy-functional organophosphorus oligomer (FR) to cotton fabric in the presence of a catalyst, such as sodium hypophosphite (NaH2PO2). Previously, it was found that the cotton fabric treated with FR and BTCA showed a high level of phosphorus retention after one home laundering cycle. However, the flame retardant properties quickly deteriorated as the number of home laundering cycles was increased. In this research, it was found that the free carboxylic acid groups bound to the cotton fabric form an insoluble calcium salt during home laundering, thus diminishing the flame retardant properties of the treated cotton fabric. It was also found that the free carboxylic acid groups on the treated cotton fabric were esterified by triethanolamine (TEA), and that the formation of calcium salt on the fabric was suppressed by the esterification of the free carboxylic acid groups by TEA. The cotton fabric treated with BTCA and the hydroxy-functional organophosphorus oligomer significantly improved its flame retardance when a new catalyst system consisting of hypophosphorous acid (H3PO2) and TEA was used in the system. Copyright © 2003 John Wiley & Sons, Ltd. [source] Interaction of heparin with Ca2+: A model study with a synthetic heparin-like hexasaccharideISRAEL JOURNAL OF CHEMISTRY, Issue 3-4 2000Jesús Angulo The binding of Ca2+ to synthetic hexasaccharide 1, containing the structural motifs of the regular region of heparin, has been investigated using NMR spectroscopy and molecular modeling. The NMR data of the calcium salt of 1 indicate the existence of specific Ca2+ binding, and molecular modeling results predict three different types of binding sites with different negative potential and preorganized geometry. The presence of Ca2+ does not seem to affect the overall helical structure of hexasaccharide 1, although it seems to have a marked influence on the flexibility of the oligosaccharide backbone. [source] Characterization of crosslinking effects on the physicochemical and drug diffusional properties of cationic hydrogels designed as bioactive urological biomaterialsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 10 2005David S. Jones This study examined the effects of concentration and type of crosslinker (tetraethyleneglycol diacrylate, TEGDA; diethyleneglycol dimethacrylate, DEGDMA; and polyethyleneglycol dimethacrylate, PEGDMA) on the mechanical and drug diffusional properties of hydrogels that had been selected as candidate coatings for bioactive medical devices. Hydrogels (dimethylaminoethylmethacrylate-covinylpyrrolidone; 1:1) were prepared by free radical polymerization and characterized using tensile analysis, dynamic contact angle analysis and analysis of swelling at pH 6.0. The release of fusidic acid and chlorhexidine was evaluated using buffered medium at pH 6.0 and, in addition, using dissolution medium that had been buffered to pH 9 in the presence and absence of elevated concentrations of calcium, representative of urinary encrustation. Crosslinker concentration, but not type, affected the advancing and receding contact angles. Conversely, both crosslinker type and concentration affected the mechanical and swelling properties of the hydrogels. Maximum swelling and elongation at break were associated with the PEGDMA-crosslinked hydrogels whereas TEGDA-crosslinked hydrogels exhibited the maximum ultimate tensile strength and Young's modulus. Drug release from all systems occurred by diffusion. The mass of chlorhexidine and fusidic acid released was dependent on crosslinker type and concentration, with hydrogels crosslinked with PEGDMA offering the greatest mass of drug released at each sampling period. The mass of fusidic acid but not chlorhexidine released at pH 9.0 in a calcium augmented medium was lower than that released in the same medium devoid of elevated calcium, due to the formation of the poorly soluble calcium salt. In conclusion, this study has uniquely examined the effects of crosslinker type and concentration on physicochemical and drug release properties essential to the clinical and non-clinical performance of bioactive hydrogels for medical device application. [source] Pentasilatricyclo[2.1.0.02,5]pentane and Its AnionCHEMISTRY - A EUROPEAN JOURNAL, Issue 34 2009Vladimir The first pentasilatricyclo[2.1.0.02,5]pentane derivative 1 has been prepared by the reaction of the calcium salt of tetrasilabicyclo[1.1.0]butan-2,4-diide with PhSiCl3. Reduction of 1 with KC8 resulted in the unexpected formation of the pentasilatricyclo[2.1.0.02,5]pentan-1-ide derivative isolated in the form of its potassium salt 2,,K+. It features an inverted tetrahedral configuration at the anionic Si center and appreciable K+, arene(Ph) , interaction, which stabilizes the anionic system. [source] Human enamel dissolution in citric acid as a function of pH in the range 2.30,pH,6.30 , a nanoindentation studyEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2003Michele E. Barbour The objective of this study was to investigate the dissolution of human enamel in citric acid solutions over a wide range of pH. The in vitro conditions are considered to be relevant to soft drink-induced enamel erosion. Nanoindentation was used to investigate changes in the nanomechanical properties of polished enamel surfaces after exposure to citric acid solutions. Solutions used had 38.1 mmol l,1 citric acid and pH greater than 2.3 but less than 6.3 (2.30 pH 6.30). Samples were exposed to rapidly stirred, constant composition solutions for 120 s. Statistically significant changes in enamel hardness and reduced elastic modulus were observed after exposure to all solutions. There was an approximately linear dependence of enamel hardness on solution pH for 2.90 pH 6.30. Below pH 2.90, enamel is thought to have reached the lowest possible hardness value. The reduction in enamel dissolution caused by an increase in pH of a soft drink is likely to be small. Product modification to reduce the erosive potential of drinks may require additional methods such as addition of calcium salts. [source] Metastatic pulmonary calcification in a dialysis patient: Case report and a reviewHEMODIALYSIS INTERNATIONAL, Issue S2 2006Christoph H. EGGERT Abstract A 19-year-old male presented with chest pain and dyspnea. He was anephric following nephrectomy for focal segmental glomerulosclerosis, had a subsequent failed transplant, and had been dialysis dependent for 3 years. Workup revealed hyperparathyroidism and an abnormal chest X-ray and computed tomography scan, significant for massive extra-skeletal pulmonary calcification. A markedly abnormal Technitium99 methylene diphosphonate (Tc99m-MDP) bone scan confirmed the clinical suspicion of metastatic pulmonary calcification. Metastatic pulmonary calcification (MPC) is common, occurring in 60% to 80% of dialysis patients on autopsy and bone scan series. It may lead to impaired oxygenation and restrictive lung disease. Typically, the calcium crystal is whitlockite rather than hydroxyapatite, which occurs in vascular calcification. Four major predisposing factors may contribute to MPC in dialysis patients. First, chronic acidosis leaches calcium from bone. Second, intermittent alkalosis favors deposition of calcium salts. Third, hyperparathyroidism tends to cause bone resorption and intracellular hypercalcemia. Finally, low glomerular filtration rate can cause hyperphosphatemia and an elevated calcium-phosphorus product. There may be other factors. Some authors suggest that the incidence of MPC in recent years may be lower due to improved dialysis techniques. The diagnosis is confirmed by biopsy, but can be suspected by typical findings on a Tc99m-MDP bone scan. Therapy is limited to ensuring adequate dialysis, correcting calcium-phosphorus product, and hyperparathyroidism; discontinuing vitamin D analogues may help. Conflicting reports show that transplantation may either improve or worsen the situation. MPC should be considered in dialysis patients who have characteristic abnormal chest radiography and/or pulmonary symptoms. [source] Presence of nanobacteria in psammoma bodies of ovarian cancer: evidence for pathogenetic role in intratumoral biomineralizationHISTOPATHOLOGY, Issue 6 2004G Hudelist Aims:, The presence of laminated, calcified extracellular debris known as psammoma bodies is a well-known histomorphological feature of ovarian adenocarcinomas and other human malignancies. Biomineralization has recently been found to be associated with a group of extremely small Gram-negative bacteria capable of precipitating calcium salts. The aim of the present study was to evaluate a possible pathogenic link between the development of psammoma bodies and nanobacteria infection. Material and results:, Immunohistochemical staining and reverse transcriptase-polymerase chain reaction (RT-PCR) were used to analyse nanobacterial protein and gene expression in eight psammona body-containing adenocarcinomas and in 10 malignant ovarian tumours without signs of biomineralization. Nanobacterial proteins were detected in eight out of eight (100%) psammoma-positive tumour samples. Conversely, none of the 10 psammoma-negative tissues (0%) was positive for nanobacterial antigens. Furthermore, nanobacterial mRNA was detectable in all of the four tissues (100%) that contained psammoma bodies, but was absent in all 10 ovarian cystadenocarcinomas (0%) that were psammoma negative. Conclusions:, We found a 100% concordance between the expression of nanobacteria and the presence of psammoma bodies in malignant ovarian tumours. Several lines of evidence suggest the involvement of these organisms in the process of biomineralization. We therefore conclude that nanobacterial infection of malignant ovarian tissue contributes to mechanisms leading to the formation of calcified deposits known as psammoma bodies. [source] Mixing calcium chloride with commercial fungicide formulations results in very slow penetration of calcium into apple fruitsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2004Thomas K. Schlegel Abstract Foliar applications of calcium salts are usually combined with fungicides. In the years 2002 and 2003, it was tested if this practice assures high rates of penetration of calcium. Amounts that penetrated in 24 h were measured at 20,°C using 45CaCl2. To ensure maximum penetration rates, humidity was maintained at 100,%. Sample size was 40 to 50 fruits, and data were presented as box plots because distribution of data was not normal. Median rates of penetration of CaCl2, measured with mixtures of fungicides and CaCl2 at 5 or 10 g l,1, respectively, were very slow, and amounted to only a few percent of the dose applied. Rates were a little higher with very young fruits (55 days after full bloom, DAFB). Adding alkyl polyglycoside surfactants at 0.2 g l,1 significantly decreased surface tensions, and increased rates of penetration by up to 15-fold. Still, total penetration of CaCl2 rarely exceeded 20,% of the dose applied (median penetration), even in the presence of an additional surfactant. In all treatments, outliers with 60 to 100,% penetration in 24 h occurred, and this was attributed to penetration into lenticels. This is expected to result in unequal concentrations of calcium in fruits, especially in the sub-epidermal layers. Addition of a suitable surfactant to mixtures of fungicides with CaCl2 is strongly recommended as it enhances wetting and greatly increases penetration rates of CaCl2. Mischen von Calciumchlorid mit Fungiziden resultiert in einer sehr langsamen Penetration von Calcium in Apfelfrüchte Zur Blattdüngung werden Calciumsalze meist mit Fungiziden gemischt. Es wurde untersucht, ob diese Praxis hohe Penetrationsraten für das ausgebrachte Calciumsalz gewährleistet. Die Penetration wurde mit 45CaCl2 bei 20,°C gemessen. Die Luftfeuchte betrug 100,%, so dass maximale Penetrationsraten erzielt wurden. Der Stichprobenumfang betrug 40 bis 50 Früchte. Die Ergebnisse werden als Box-Plots präsentiert, weil die Verteilung der Daten nicht normal war. Bei Mischungen von CaCl2 (5 bis 10 g l,1) mit Fungiziden betrugen die Mediane der Penetrationsraten von CaCl2 nur einige Prozent. Bei sehr jungen Früchten (55 Tage nach Vollblüte, DAFB) waren die Raten etwas höher als bei älteren. Durch Zugabe von Alkyl-Polyglykosiden (0.2 g l,1) wurden die Oberflächenspannungen der Lösungen verringert und die Penetration von Calcium bis zu 15fach erhöht. Trotzdem betrug die Penetration in 24 h nur selten mehr als 20,% der Dosis. In allen Behandlungen wurden Ausreißer beobachtet, bei denen die Penetration in 24 h 60 bis 100,% der Dosis betrug. Das wurde auf Infiltration von Lentizellen zurückgeführt. Dadurch dürfte die Calciumkonzentration in Früchten nach Spritzung mit CaCl2 nicht homogen sein, besonders nicht in den subepidermalen Schichten. Die Zugabe eines geeigneten Netzmittels zu Mischungen von Fungiziden mit CaCl2 wird empfohlen. Dadurch wird die Benetzung der Früchte verbessert, und die Penetrationsraten werden erhöht. [source] Surfactant assisted polymerization of tetrafluoroethylene in supercritical carbon dioxide with a pilot scale batch reactorJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2008Alberto Giaconia Abstract Chain-free radical polymerization of tetrafluoroethylene (TFE) was carried out in supercritical carbon dioxide (scCO2), at 50 °C and 121,133 bar, with tertiary -amyl-per-pivalate as a free radical initiator, using a 5-L pilot scale batch reactor. Experiments were carried out both in the absence and in the presence of perfluoropolyether (PFPE) carboxylate surfactants. Stabilizers were employed under the free acid form and as sodium and calcium salts. An expanded fibrillated poly(TFE) was obtained in all experiments. In the case of surfactant-free polymerizations, the product was mainly constituted by irregular shape macroparticles having size in the range 200,500 ,m. Quite interestingly, when the free acid surfactant was used, a clear acceleration of the polymerization rate was observed and smaller polymer particles with more regular quasi-spherical morphology were obtained. Melt fusion crystallinity of as-polymerized poly(TFE) seemed not substantially affected by the presence of the stabilizers and was rather high (80,86%) suggesting that polymerization mainly occurs at polymer particle surface. All these elements suggest that FLUOROLINK® 7004H PFPE carboxylic acid decreases coagulation of primary polymer particles leading to an increase in polymer surface area. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 257,266, 2008 [source] Calcium L -edge XANES study of some calcium compoundsJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001S. J. Naftel The Ca L3,2 -edge XANES spectra of six calcium salts have been measured in both total electron and fluorescence yields using a high-resolution spherical grating monochromator. The compounds investigated were; CaF2, CaCO3, CaCl2,2H2O, calcium phosphate, calcium glycerophosphate and calcium gluconate. We find that the fine structure of the Ca L3,2 -edges for each compound is unique and relates to the local structure of the Ca atom. The implications of these results to the study of the structure of calcium binding sites in systems of biologically interest will be discussed. [source] RHEOLOGY OF DOUBLE (W/O/W) EMULSIONS PREPARED WITH SOYBEAN MILK AND FORTIFIED WITH CALCIUMJOURNAL OF TEXTURE STUDIES, Issue 5 2010ANDRÉS L. MÁRQUEZ ABSTRACT The objective of this work was to study the rheological behavior of water-in-oil-in-water (w/o/w) emulsions prepared with soybean milk and sunflower oil, with different calcium solutions as the internal aqueous phase, in order to evaluate them as a vegetable substitute of whipped dairy cream. The obtained systems exhibited a creamy texture, which was attributed to the swelling of w/o droplets because of the osmotic gradient generated by the inclusion of soluble salts in the internal aqueous phase. A secondary factor could be the flocculation of w/o droplets due to the interaction of released calcium with soybean proteins at the interface. Consequently, the increase of calcium chloride content produced emulsions with higher consistency. A pasteurization produced flocculation and coalescence of w/o droplets only at high calcium chloride content. These double emulsions could be a potential alternative to the whipped dairy cream, because of their texture, reduced fat content and calcium contribution. PRACTICAL APPLICATIONS This article deals with the formulation of novel calcium-fortified food emulsions prepared with soybean milk and sunflower oil. Because calcium needs to be isolated from soybean milk components (proteins and phospholipids), we proposed to include calcium salts in the internal aqueous phase of a water-in-oil-in-water (w/o/w) emulsion. The practical applications of this research could include the formulation of low lipid content emulsions and the isolation of a component which is incompatible with the continuous aqueous phase. Particularly, this work leads to the understanding of how the inclusion of calcium salts in the internal aqueous phase of a w/o/w emulsion prepared with soybean milk affects the rheology and microstructure of the system. The results led to the conclusion that these emulsions can work as a whipped dairy cream substitute with vegetal components, low lipid content and important calcium contribution. [source] Ca2+ -Mediated Interaction Between Microsilica and Polycarboxylate Comb Polymers in a Model Cement Pore SolutionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010Matthias Lesti Interaction between polycarboxylate (PCE) comb polymers and microsilica suspended in a highly alkaline, Ca2+ -loaded model cement pore solution was studied via zeta potential, adsorption, and paste flow experiments. Zeta potential measurements reveal that in an alkaline suspension, microsilica possesses a negative surface charge stemming from deprotonated silanolate groups. Addition of soluble calcium salts (e.g., CaCl2) was found to cause a charge reversal to positive, owing to the adsorption of Ca2+ ions forming a monolayer on the microsilica surface. Further experiments demonstrate that through Ca2+ mediation, anionic PCE graft polymers adsorb in high amount on the microsilica surface. Polymers possessing a stronger anionic character exhibit a higher affinity to the positive microsilica surface, and consequently, exercise a more powerful dispersing effect than PCE showing less anionic character. A model summarizing the processes occurring at the surface of microsilica in this fluid system is proposed. The study suggests that the high fluidity of concrete containing microsilica depends on the effective dispersion of microsilica, and not of cement. [source] Mineral contents and distribution between the soluble and the micellar phases in calcium-enriched UHT milksJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2004Miguel Angel de la Fuente Abstract A study concerning the content of mineral elements (calcium, magnesium, sodium, potassium and phosphorus) and the distribution between the soluble and the micellar phases has been carried out on mineral,mainly calcium,enriched UHT milks. Total calcium contents were 1371,1793 mg l,1 in the 10 brands examined. Percentages of calcium in the soluble phase varied from 23.6 to 37.2%, whereas ionic calcium concentrations found were within a very wide range (44,91 mg l,1). The different forms of phosphorus were studied by 31P-NMR. Spectra indicated that the majority of the brands employed polyphosphates as stabilizers. Ingredients used to fortify these products consisted of dairy fractions and calcium salts. The modifications in salt balance as consequence of these practices are discussed. Copyright © 2004 Society of Chemical Industry [source] Management of secondary hyperparathyroidism of dialysis patientsNEPHROLOGY, Issue 2003Tadao AKIZAWA SUMMARY: Hyperphosphatemia, vitamin D deficiency, and resulted hypocalcemia have been regarded as classical pathogeneses of secondary hyperparathyroidism. These factors have been treated by the administration of phosphorus binder and vitamin D derivatives. However, these therapies have not brought about a successful result for the prevention and treatment of secondary hyperparathyroidism. The reason could be mainly attributed to the hypercalcemia that results from the administration of calcium salts as a phosphorus binder and the calcemic action of vitamin D. To prevent hypercalcemia, non-calcium containing phosphorus binder (sevelamer hydrochloride) and vitamin D analogues, which suppress PTH secretion with minimum calcemic action, have been developed. These new vitamin D analogues include 19-nor-1-alpha, 25-dihydroxyvitamin D2 (paricalcitol), 1-alpha-hydroxyvitamin D2 (doxercalciferol), 22oxa-calcitriol (maxacalcitol) and F6-calcitriol (falecalcitriol). Furthermore, calcimimetics that stimulate calcium-sensing receptor of parathyroid cells as calcium and suppress PTH secretion are now under clinical trial. Percutaneous direct injection therapy of vitamin D, vitamin D analogue or calcimimetics into parathyroid gland has also been reported. The combination of these new strategies is expected to effectively and safely suppresses secondary hyperparathyroidism that has been resistant to conventional medical treatments. [source] Phytate prevents tissue calcifications in female ratsBIOFACTORS, Issue 3 2000F. Grases The AIN-76 A, a purified rodent diet, has a propensity to cause kidney calcifications in female rats which is not observed with non-purified rodent diets, suggesting a nutritional factor that avoids these calcifications. One candidate is phytate, which inhibits crystallisation of calcium salts and is practically absent in purified diets. Therefore, the effects on calcification of kidney tissue of phytate addition to the AIN-76 A diet using female Wistar rats were studied. The rats were assigned to three groups: AIN-76 A, AIN-76 A + 1% phytate and standard nonpurified chow. Urinary phytate of the AIN-76 A fed group was undetectable. Urinary phytate of AIN-76 A + 1% phytate and standard fed groups did not differ and was significantly higher than in the AIN-76 A group. The concentrations of calcium and phosporus in kidneys were greater in the AIN-76 A group than in AIN-76 A + 1% phytate and standard groups. Only rats of the AIN-76 A group displayed mineral deposits at the corticomedullary junction. These findings demonstrated that the absence of phytate in the AIN-76 A diet is one of the causes of renal calcification in female rats. [source] Study of a myo -inositol hexaphosphate-based cream to prevent dystrophic calcinosis cutisBRITISH JOURNAL OF DERMATOLOGY, Issue 5 2005F. Grases Summary Background, Calcinosis cutis is a disorder caused by abnormal deposits of calcium phosphate in the skin and is observed in diverse disorders. Myo -inositol hexaphosphate (InsP6) is a diet-dependent molecule found in all mammalian fluids and tissues, which exhibits an extraordinary capacity as a crystallization inhibitor of calcium salts. Objectives, To establish the effects of topically administered InsP6 cream on artificially provoked dystrophic calcifications in soft tissues. Methods, Fourteen male Wistar rats were randomly assigned into two groups: control and treated groups. Rats were fed with an InsP6 -free or phytate diet. Plaque formation was induced by subcutaneous injection of 0·1% KMnO4 solution. From 4 days before plaque induction to the end of the experiment, control rats were treated topically with a standard cream, whereas treated rats were treated with the same cream with 2% InsP6 or phytate (as sodium salt). Calcification of plaques was allowed to proceed for 10 days. InsP6 in urine was determined. The plaques were excised and weighed. Results, It was found that when InsP6 was administered topically through a moisturizing cream (2% InsP6 -rich), the plaque size and weight were notably and significantly reduced compared with the control group (1·6 ± 1·1 mg InsP6 -treated, 26·7 ± 3·0 mg control). The InsP6 urinary levels for animals treated with the InsP6 -enriched cream were considerably and significantly higher than those found in animals treated topically with the cream without InsP6 (16·96 ± 4·32 mg L,1 InsP6 -treated, 0·06 ± 0·03 mg L,1 control). Conclusions, This demonstrates the important capacity of InsP6 as a crystallization inhibitor and also demonstrates that it is possible to propose topical use as a new InsP6 administration route. [source] | ||||||||||||||||