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Sample records for calcium hydroxide solutions

  1. Conversion coatings prepared or treated with calcium hydroxide solutions

    NASA Technical Reports Server (NTRS)

    Minevski, Zoran (Inventor); Clarke, Eric (Inventor); Maxey, Jason (Inventor); Nelson, Carl (Inventor); Eylem, Cahit (Inventor)

    2002-01-01

    A conversion coating process that forms a stable and corrosion-resistant oxide layer on metal or metal oxide substrates or layers. Particularly, the conversion coating process involves contacting the metal or metal oxide substrate or layer with the aqueous calcium hydroxide solutions in order to convert the surface of the substrate to a stable metal oxide layer or coating. According to the present invention, the calcium hydroxide solution is prepared by removing carbon dioxide from water or an aqueous solution before introducing the calcium hydroxide. In this manner, formation of calcium carbonate particles is avoided and the porosity of the conversion coating produced by the calcium hydroxide solution is reduced to below about 1%.

  2. Calcium hydroxide poisoning

    MedlinePlus

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  3. Ion Association versus Ion Interaction Models in Examining Electrolyte Solutions: Application to Calcium Hydroxide Solubility Equilibrium

    ERIC Educational Resources Information Center

    Menéndez, M. Isabel; Borge, Javier

    2014-01-01

    The heterogeneous equilibrium of the solubility of calcium hydroxide in water is used to predict both its solubility product from solubility and solubility values from solubility product when inert salts, in any concentration, are present. Accepting the necessity of including activity coefficients to treat the saturated solution of calcium…

  4. 21 CFR 184.1205 - Calcium hydroxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium hydroxide. 184.1205 Section 184.1205 Food... Specific Substances Affirmed as GRAS § 184.1205 Calcium hydroxide. (a) Calcium hydroxide (Ca(OH)2, CAS Reg. No. 1305-62-0) is also known as slaked lime or calcium hydrate. It is produced by the hydration...

  5. 21 CFR 582.1205 - Calcium hydroxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium hydroxide. 582.1205 Section 582.1205 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1205 Calcium hydroxide. (a) Product. Calcium hydroxide. (b) Conditions of use....

  6. Synthesis, Thermodynamic, and Kinetics of Rubidium Jarosite Decomposition in Calcium Hydroxide Solutions

    NASA Astrophysics Data System (ADS)

    Perez-Labra, Miguel; Romero-Serrano, Antonio; Salinas-Rodriguez, Eleazar; Avila-Davila, Erika O.; Reyes-Perez, Martin

    2012-08-01

    Rubidium jarosite was synthesized as a single phase by precipitation from aqueous solution. X-ray diffraction and scanning electron microscopy energy-dispersive spectrometry analysis showed that the synthetic product is a solid rubidium jarosite phase formed in spherical particles with an average particle size of about 35 μm. The chemical analysis showed an approximate formula of Rb0.9432Fe3(SO4)2.1245(OH)6. The decomposition of jarosite in terms of solution pH was thermodynamically modeled using FACTSage by constructing the potential pH diagram at 298 K (25 °C). The E-pH diagram showed that the decomposition of jarosite leads to a goethite compound (FeO·OH) together with Rb+ and {{SO}}4^{2 - } ions. The experimental Rb-jarosite decomposition was carried out in alkaline solutions with five different Ca(OH)2 concentrations. The decomposition process showed a so-called "induction period" followed by a progressive conversion period where Rb+ and {{SO}}4^{2 - } ions formed in the aqueous solutions, whereas calcium was incorporated in the solid residue and iron gave way to goethite. The kinetic analysis showed that this process can be represented by the shrinking core chemically controlled model with a reaction order with respect to Ca(OH)2 equals 0.4342 and the calculated activation energy is 98.70 kJ mol-1.

  7. Investigation of early growth of calcium hydroxide crystals in cement solution by soft x-ray transmission microscopy

    SciTech Connect

    Harutyunyan, V. S.; Kirchheim, A. P.; Monteiro, P. J. M.; Aivazyan, A. P.; Fischer, P.

    2009-02-02

    Research on cement hydration was performed at the full-field soft transmission X-ray microscope XM-1 located at beamline 6.1.2 at the Advanced Light Source (ALS) in Berkeley CA which is operated by the Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California. A series of works [1-3] has been conducted using this microscope for the in situ observation and qualitative analysis of through-solution hydration products and products of topochemical reactions, which form in cementitious aqueous solutions. This paper studies the precipitation of the calcium hydroxide (CH) crystals from the cement solution. The analysis of successive images of the hydration process provides critical quantitative information about the growth rate of calcium hydroxide (CH) crystals, the supersaturation ratio, and the kinetic and diffusion coefficients of the growth process. ASTM Type II portland cement and 6% C{sub 4}A{sub 3}{bar S} admixture were mixed in aqueous solution and saturated with respect to CH and gypsum. The C{sub 4}A{sub 3}{bar S} admixture was included in the experimental program because of the general research program on expansive cements, and adding C{sub 4}A{sub 3}{bar S} to portland cement is an efficient method of generating ettringite and significant early-age expansion. The solution/solid materials ratio was 10 cm{sup 3}/g, which is higher than the one existing in regular concrete and mortars; to compensate for this dilution, the solution was originally saturated with CH and gypsum. To allow sufficient transmission of the soft X-rays, a small droplet was taken from the supernatant solution and assembled in the sample holder, and then squeezed between two silicon nitride windows for the analysis. The X-ray optical setup of the microscope XM-1 is described elsewhere [2]. In this experiment, a wavelength of 2.4 nm (516.6 eV) was used. The radiation transmitting the sample was detected using an X-ray CCD camera, with a resolution of 35 nm provided

  8. 21 CFR 582.1205 - Calcium hydroxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Calcium hydroxide. 582.1205 Section 582.1205 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE General Purpose...

  9. 21 CFR 872.3250 - Calcium hydroxide cavity liner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Calcium hydroxide cavity liner. 872.3250 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3250 Calcium hydroxide cavity liner. (a) Identification. A calcium hydroxide cavity liner is a device material intended to be applied to the interior of...

  10. 21 CFR 872.3250 - Calcium hydroxide cavity liner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Calcium hydroxide cavity liner. 872.3250 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3250 Calcium hydroxide cavity liner. (a) Identification. A calcium hydroxide cavity liner is a device material intended to be applied to the interior of...

  11. 21 CFR 872.3250 - Calcium hydroxide cavity liner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Calcium hydroxide cavity liner. 872.3250 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3250 Calcium hydroxide cavity liner. (a) Identification. A calcium hydroxide cavity liner is a device material intended to be applied to the interior of...

  12. 21 CFR 872.3250 - Calcium hydroxide cavity liner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Calcium hydroxide cavity liner. 872.3250 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3250 Calcium hydroxide cavity liner. (a) Identification. A calcium hydroxide cavity liner is a device material intended to be applied to the interior of...

  13. Analysis of barium hydroxide and calcium hydroxide slurry carbonation reactors

    SciTech Connect

    Patch, K.D.; Hart, R.P.; Schumacher, W.A.

    1980-05-01

    The removal of CO/sub 2/ from air was investigated by using a continuous-agitated-slurry carbonation reactor containing either barium hydroxide (Ba(OH)/sub 2/) or calcium hydroxide (Ca(OH)/sub 2/). Such a process would be applied to scrub /sup 14/CO/sub 2/ from stack gases at nuclear-fuel reprocessing plants. Decontamination factors were characterized for reactor conditions which could alter hydrodynamic behavior. An attempt was made to characterize reactor performance with models assuming both plug flow and various degrees of backmixing in the gas phase. The Ba(OH)/sub 2/ slurry enabled increased conversion, but apparently the process was controlled under some conditions by phenomena differing from those observed for carbonation by Ca(OH)/sub 2/. Overall reaction mechanisms are postulated.

  14. Antimicrobial Activity of Calcium Hydroxide in Endodontics: A Review

    PubMed Central

    Shalavi, S; Yazdizadeh, M

    2012-01-01

    The purpose of endodontic therapy is to preserve the patient's natural teeth without compromising the patient's local or systemic health. Calcium hydroxide has been included in several materials and antimicrobial formulations that are used in several treatment modalities in endodontics, such as inter-appointment intracanal medicaments. The purpose of this article was to review the antimicrobial properties of calcium hydroxide in endodontics. Calcium hydroxide has a high pH (approximately 12.5-12.8) and is classified chemically as a strong base. The lethal effects of calcium hydroxide on bacterial cells are probably due to protein denaturation and damage to DNA and cytoplasmic membranes. Calcium hydroxide has a wide range of antimicrobial activity against common endodontic pathogens but is less effective against Enterococcus faecalis and Candida albicans. Calcium hydroxide is also a valuable anti-endotoxin agent. However, its effect on microbial biofilms is controversial. PMID:23323217

  15. 21 CFR 872.3250 - Calcium hydroxide cavity liner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Calcium hydroxide cavity liner. 872.3250 Section 872.3250 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3250 Calcium hydroxide cavity liner....

  16. Calcium hydroxide-based root canal sealers: a review.

    PubMed

    Desai, Shalin; Chandler, Nicholas

    2009-04-01

    The aim of this review was to consider laboratory experiments and clinical studies of calcium hydroxide-based root canal sealers. An extensive search of the endodontic literature was made to identify publications related to calcium hydroxide-based root canal sealers. The articles were assessed for the outcome of laboratory and clinical studies on their biological properties and physical characteristics. Comparative studies with other sealers were also considered. Several studies were evaluated covering different properties of calcium hydroxide-based sealers including physical properties, biocompatibility, leakage, adhesion, solubility, antibacterial properties, and periapical healing effect. Calcium hydroxide-based root canal sealers have a variety of physical and biological properties. Comparative studies reveal their mild cytotoxicity, but their antibacterial effects are variable. Further research is required to establish the tissue healing properties of calcium hydroxide in root canal sealers. PMID:19345790

  17. Thermochemistry of calcium oxide and calcium hydroxide in fluoride slags

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, S.; Mitchell, A.

    1990-08-01

    Calcium oxide activity in binary CaF2-CaO and ternary CaF2-CaO-Al2O3 and CaF2-CaO-SiO2 slags has been determined by CO2-slag equilibrium experiments at 1400 °C. The carbonate ca-pacity of these slags has also been computed and compared with sulfide capacity data available in the literature. The similarity in trends suggests the possibility of characterizing carbonate capacity as an alternative basicity index for fluoride-base slags. Slag-D2O equilibrium experi-ments are performed at 1400°C with different fluoride-base slags to determine water solubility at two different partial pressures of D2O, employing a new slag sampling technique. A novel isotope tracer detection technique is employed to analyze water in the slags. The water solubility data found show higher values than the previous literature data by an order of magnitude but show a linear relationship with the square root of water vapor partial pressure. The activity of hydroxide computed from the data is shown to be helpful in estimating water solubility in in-dustrial electroslag remelting (ESR) slags.

  18. Biocompatibility of Intracanal Medications Based on Calcium Hydroxide

    PubMed Central

    Andolfatto, Carolina; da Silva, Guilherme Ferreira; Cornélio, Ana Livia Gomes; Guerreiro-Tanomaru, Juliane Maria; Tanomaru-Filho, Mario; Faria, Gisele; Bonetti-Filho, Idomeo; Cerri, Paulo Sérgio

    2012-01-01

    Objective. The aim of this study was to evaluate the rat subcutaneous tissue reaction to calcium hydroxide-based intracanal medicaments, UltraCal XS (calcium hydroxide, barium sulphate, aqueous matrix), Hydropast (calcium hydroxide, barium sulphate, and propyleneglycol), and Calen (Calcium hydroxide, zinc oxide, colophony, and polyethyleneglycol), used as a control. Methods. Forty-eight rats (Rattus Norvegicus Holtzman) were distributed in three groups: Calen, UltraCal XS, and Hydropast. Polyethylene tubes filled with one of the medicaments were implanted in the dorsal subcutaneous. After 7 and 30 days, the implants were removed and the specimens were fixed and embedded in paraffin. Morphological and quantitative analyses were carried out in the HE-stained sections. The numerical density of inflammatory cells in the capsule was evaluated and statistical analyses were performed (P ≤ 0.05). Results. At 7 days, all materials induced an inflammatory reaction in the subcutaneous tissue adjacent to the implants. In all groups, a significant reduction in the number of inflammatory cells and giant cells was verified in the period of 30 days. Conclusion. These results indicate that the calcium hydroxide-based medicaments evaluated present biocompatibility similar to Calen. PMID:23320187

  19. Effect of Calcium Hydroxide on the Fracture Resistance of Dentin

    PubMed Central

    Whitbeck, Evan R.; Quinn, George D.; Quinn, Janet B.

    2011-01-01

    An increased incidence of fracture has been reported in teeth where root canals were treated with calcium hydroxide. Edge chipping is one test used to measure the resistance of brittle materials to fracture. Presently, no studies have reported on edge chipping in teeth. This study evaluated the fracture resistance of human dentin exposed to calcium hydroxide for up to 60 days using the edge chipping method. Twelve recently extracted teeth were divided into a control group and three experimental groups with varying calcium hydroxide exposures. All teeth underwent pulpectomy via standard protocol. It was expected that the edge chip resistance would decrease as a function of exposure, but the results showed the converse. Chip resistance may reflect both the fracture resistance and the hardness of dentin, a quasi brittle material. PMID:26989596

  20. LIGNOSULFONATE-MODIFIED CALCIUM HYDROXIDE FOR SULFUR DIOXIDE CONTROL

    EPA Science Inventory

    The article discusses the use of lignosulfonate-modified calcium hydroxide Ca(OH)2 for sulfur dioxide (SO2) control. The limestone injection multistage burner (LIMB) process is currently being developed at the U.S. EPA as a low cost retrofittable technology for controlling oxides...

  1. INFLUENCE OF IODOFORM ON ANTIMICROBIAL POTENTIAL OF CALCIUM HYDROXIDE

    PubMed Central

    Estrela, Carlos; Estrela, Cyntia Rodrigues de Araújo; Hollanda, Augusto César Braz; Decurcio, Daniel de Almeida; Pécora, Jesus Djalma

    2006-01-01

    The purpose of this research was to verify the influence of Iodoform on antimicrobial potential of calcium hydroxide. S. aureus, E. faecalis, P. aeruginosa, B. subtilis, C. albicans were the biological indicators. The substances tested were: calcium hydroxide + saline; calcium hydroxide + Iodoform + saline; Iodoform + saline. For the agar diffusion test, 18 Petri plates with 20 ml of BHI agar were inoculated with the microbial suspensions. Fifty-four cavities were made and filled with the substances tested. The diameters of microbial inhibition were then measured. In direct exposure test, 162 #50 sterile absorbent paper points were immersed in the experimental suspensions for 5 min, and covered with the pastes. At intervals of 24, 48 and 72 hours, the paper points were immersed in 10 ml of Letheen Broth, followed by incubation at 37°°C for 48h. Microbial growth was evaluated by turbidity of the culture medium. A 0.1 ml inoculum obtained from the Letheen Broth was transferred to 7 ml of BHI, and incubated at 37°°C for 48h. Bacterial growth was again evaluated by turbidity of the culture medium. The calcium hydroxide associated with the saline or the iodoform plus saline showed antimicrobial effectiveness in both experimental methods. The iodoform paste presented antimicrobial ineffectiveness for the agar diffusion test on all biological microorganisms and for the direct exposure test on B. subtilis and on the mixture. PMID:19089027

  2. 40 CFR 415.310 - Applicability; description of the calcium hydroxide production subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... calcium hydroxide production subcategory. 415.310 Section 415.310 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Hydroxide Production Subcategory § 415.310 Applicability; description of the calcium hydroxide production subcategory. The provisions of this subpart are applicable to...

  3. Evaluation of calcium ion release and change in pH on combining calcium hydroxide with different vehicles

    PubMed Central

    Grover, Charu; Shetty, Neeta

    2014-01-01

    Introduction: Intracanal medicaments have traditionally been used in endodontics to disinfect root canals between appointments. Calcium hydroxide is widely used as an intracanal medicament for disinfection and to promote periapical healing. It is stable for long periods, harmless to the body, and bactericidal in a limited area. The efficacy of calcium hydroxide as a disinfectant is dependent on the availability of the hydroxyl ions in the solution that depends on the vehicle in which the calcium hydroxide is carried. In general, three types of vehicles are used: Aqueous, viscous or oily. Some in vitro studies have shown that the type of vehicle has a direct relationship with the concentration and the velocity of ionic liberation as well as with the antibacterial action when the paste is carried into a contaminated area. Aim of the Study: To evaluate the calcium ion release and measure the change in pH of the environment that occurred when calcium hydroxide was combined with different vehicles (distilled water, propylene glycol, calcium hydroxide containing gutta-percha points and chitosan) over different time periods. Materials and Methods: Forty single rooted mandibular first premolar teeth were decoronated for this study. Working length was established and the root canals were enlarged and irrigation accomplished with 2 ml of NaOCl solution after every file. The teeth were then randomly divided into four groups. The canals were then packed with different preparations of calcium hydroxide using the following vehicles-distilled water, propylene glycol, gutta-percha points and chitosan. Calcium ion release in different groups was analyzed using an ultraviolet spectrophotometer at 220 nm. The change in pH of was determined using a pH meter. Results were statistically evaluated using one-way ANOVA test. Result: For calcium ion release, Group 2 showed cumulative drug release of 81.97% at the end of 15 days, whereas Group 1, 3 and 4 showed a release of 99.53, 17.98, 74

  4. The effect of radiopacifiers agents on pH, calcium release, radiopacity, and antimicrobial properties of different calcium hydroxide dressings.

    PubMed

    Ordinola-Zapata, Ronald; Bramante, Clovis Monteiro; García-Godoy, Franklin; Moldauer, Bertram Ivan; Gagliardi Minotti, Paloma; Tercília Grizzo, Larissa; Duarte, Marco Antonio Hungaro

    2015-07-01

    The aim of this study was to evaluate the antimicrobial activity, pH level, calcium ion release, and radiopacity of calcium hydroxide pastes associated with three radiopacifying agents (iodoform, zinc oxide, and barium sulfate). For the pH and calcium release tests, 45 acrylic teeth were utilized and immersed in ultrapure water. After 24 h, 72 h, and 7 days the solution was analyzed by using a pH meter and an atomic absorption spectrophotometer. Polyethylene tubes filled with the pastes were used to perform the radiopacity test. For the antimicrobial test, 25 dentin specimens were infected intraorally in order to induce the biofilm colonization and treated with the pastes for 7 days. The Live/Dead technique and a confocal microscope were used to obtain the ratio of live cells. Parametric and nonparametric statistical tests were performed to show differences among the groups (P < 0.05). The pH analysis at 7 days showed significant differences (P < 0.05) among the groups. No differences among the pastes were found in the calcium release test on the 7th day (P > 0.05). The calcium hydroxide/iodoform samples had the highest radiopacity and antimicrobial activity against the biofilm-infected dentin in comparison to the other pastes (P < 0.05). Calcium hydroxide mixed with 17% iodoform and 35% propylene glycol into a paste had the highest pH, calcium ion release, radiopacity, and the greatest antimicrobial action versus similar samples mixed with BaSO4 or ZnO. PMID:25990864

  5. The effects of lithium hydroxide solution on alkali silica reaction gels created with opal

    SciTech Connect

    Mitchell, Lyndon D.; Beaudoin, James J.; Grattan-Bellew, Patrick

    2004-04-01

    The reaction of Nevada opal with calcium hydroxide, potassium hydroxide and lithium hydroxide solutions was investigated. In addition, opal was exposed to a combined solution of these three hydroxides. The progress of the three reactions was followed using X-ray diffraction (XRD), {sup 29}Si nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). The XRD results indicated the presence of a low-angle peak exclusive to the lithium-based reactions. The NMR results suggested a change in the silicate structure in the presence of lithium. These techniques indicated that the reaction of the alkali with the opal starting material is inhibited and perhaps stopped in the presence of lithium hydroxide. SEM revealed that the morphology of the reaction products on the surface of the reacted opal grains is markedly different invariably. It was concluded that evidence to support the theory of a protective layer exists and that the nature of the layer varies with ion type.

  6. Effects of calcium hydroxide and calcium chloride addition to bentonite in iron ore pelletization.

    PubMed

    Tugrul, Nurcan; Derun, Emek Moroydor; Pişkin, Mehmet

    2006-10-01

    Pyrite ash is created as waste from the roasting of pyrite ores during the production of sulphuric acid. These processes generate great amounts of pyrite ash waste that is generally land filled. This creates serious environmental pollution due to the release of acids and toxic substances. Pyrite ash waste can be utilized in the iron production industry as a blast furnace feed to process this waste and prevent environmental pollution. The essential parameters affecting the pelletization process of pyrite ash were studied using bentonite as a binder. Experiments were then carried out using bentonite and a mixture of bentonite with calcium hydroxide and calcium chloride in order to make the bentonite more effective. The metallurgical properties of pyrite ash, bentonite, calcium hydroxide, calcium chloride, a mixture of these and sintered pellets were studied using X-ray analysis. The crushing strength tests were carried out to investigate the strength of pyrite ash waste pellets. The results of these analyses showed that pyrite ash can be agglomerated to pellets and used in the iron production industry as a blast furnace feed. The crushing strength of the pellets containing calcium hydroxide and calcium chloride in addition to bentonite was better than the strength of pellets prepared using only bentonite binder. PMID:17121116

  7. Calcium hydroxide-based root canal sealers: an updated literature review.

    PubMed

    Mohammadi, Zahed; Karim Soltani, Mohammad; Shalavi, Sousan; Yazdizadeh, Mohammad; Jafarzadeh, Mansour

    2014-05-01

    Calcium hydroxide was originally introduced to the field of endodontics by Herman in 1920 as a pulp-capping agent. Sealers play an important role in sealing the root canal system with the entombment of remaining microorganisms and filling inaccessible areas of prepared canals. This article reviews sealing ability, biocompatibility, antibacterial activity, solubility, and toxicity of calcium hydroxide based root canal sealers. PMID:24841038

  8. Properties and applications of calcium hydroxide in endodontics and dental traumatology.

    PubMed

    Mohammadi, Z; Dummer, P M H

    2011-08-01

    Calcium hydroxide has been included within several materials and antimicrobial formulations that are used in a number of treatment modalities in endodontics. These include, inter-appointment intracanal medicaments, pulp-capping agents and root canal sealers. Calcium hydroxide formulations are also used during treatment of root perforations, root fractures and root resorption and have a role in dental traumatology, for example, following tooth avulsion and luxation injuries. The purpose of this paper is to review the properties and clinical applications of calcium hydroxide in endodontics and dental traumatology including its antibacterial activity, antifungal activity, effect on bacterial biofilms, the synergism between calcium hydroxide and other agents, its effects on the properties of dentine, the diffusion of hydroxyl ions through dentine and its toxicity. Pure calcium hydroxide paste has a high pH (approximately 12.5-12.8) and is classified chemically as a strong base. Its main actions are achieved through the ionic dissociation of Ca(2+) and OH(-) ions and their effect on vital tissues, the induction of hard-tissue deposition and the antibacterial properties. The lethal effects of calcium hydroxide on bacterial cells are probably due to protein denaturation and damage to DNA and cytoplasmic membranes. It has a wide range of antimicrobial activity against common endodontic pathogens but is less effective against Enterococcus faecalis and Candida albicans. Calcium hydroxide is also an effective anti-endotoxin agent. However, its effect on microbial biofilms is controversial. PMID:21535021

  9. ASSOCIATION OF CALCIUM HYDROXIDE AND METRONIDAZOLE IN THE TREATMENT OF DOG'S TEETH WITH CHRONIC PERIAPICAL LESION

    PubMed Central

    Panzarini, Sônia Regina; Souza, Valdir; Holland, Roberto; Dezan, Eloi

    2006-01-01

    One of the primary objectives of endodontic treatment of teeth with pulp necrosis is the elimination of microorganisms from the root canal system, as effectively as possible, especially in cases with chronic periapical lesions. AIM: The purpose of this study was to analyze the response of the periapical tissue of dogs' teeth with chronic periapical lesions to endodontic treatment performed with utilization of metronidazole, calcium hydroxide, and an association of both as root canal dressings. METHODOLOGY: Forty root canals were submitted to pulpectomy and the root canals were kept exposed to the oral environment for 6 months. Then, they were submitted to biomechanical preparation and divided into 4 study groups with 10 specimens: group I – no root canal dressing; group II – calcium hydroxide; group III – metronidazole; group IV – calcium hydroxide associated to metronidazole. After 15 days, the root canals were filled with Fill Canal sealer. After 90 days, the animals were killed and the especimens processed for histological analysis. RESULTS: Calcium hydroxide dressing provided a significantly better outcome compared to other experimental groups (α = 0.01). Also, the results of the association of metronidazole and calcium hydroxide were similar to those observed for the metronidazole group. The worst results were obtained by the no root canal dressing group. CONCLUSION: The use of metronidazole alone or associated with Calcium hydroxide, did not improve periapical healing when compared to Calcium hydroxide dressing. PMID:19089054

  10. Evaluation of calcium ion, hydroxyl ion release and pH levels in various calcium hydroxide based intracanal medicaments: An in vitro study

    PubMed Central

    Fulzele, Punit; Baliga, Sudhindra; Thosar, Nilima; Pradhan, Debaprya

    2011-01-01

    Aims: Evaluation of calcium ion and hydroxyl ion release and pH levels in various calcium hydroxide based intracanal medicaments. Objective: The purpose of this study was to evaluate calcium and hydroxyl ion release and pH levels of calcium hydroxide based products, namely, RC Cal, Metapex, calcium hydroxide with distilled water, along with the new gutta-percha points with calcium hydroxide. Materials and Methods: The materials were inserted in polyethylene tubes and immersed in deionized water. The pH variation, Ca++ and OH- release were monitored periodically for 1 week. Statistical Analysis Used: Statistical analysis was carried out using one-way analysis of variance and Tukey's post hoc tests with PASW Statistics version 18 software to compare the statistical difference. Results: After 1 week, calcium hydroxide with distilled water and RC Cal raised the pH to 12.7 and 11.8, respectively, while a small change was observed for Metapex, calcium hydroxide gutta-percha points. The calcium released after 1 week was 15.36 mg/dL from RC Cal, followed by 13.04, 1.296, 3.064 mg/dL from calcium hydroxide with sterile water, Metapex and calcium hydroxide gutta-percha points, respectively. Conclusions: Calcium hydroxide with sterile water and RC Cal pastes liberate significantly more calcium and hydroxyl ions and raise the pH higher than Metapex and calcium hydroxidegutta-percha points. PMID:22346155

  11. Toxicity of Calcium Hydroxide Nanoparticles on Murine Fibroblast Cell Line

    PubMed Central

    Dianat, Omid; Azadnia, Sina; Mozayeni, Mohammad Ali

    2015-01-01

    Introduction: One of the major contributing factors, which may cause failure of endodontic treatment, is the presence of residual microorganisms in the root canal system. For years, most dentists have been using calcium hydroxide (CH) as the intracanal medicament between treatment sessions to eliminate remnant microorganisms. Reducing the size of CH particles into nanoparticles enhances the penetration of this medicament into dentinal tubules and increases their antimicrobial efficacy. This in vitro study aimed to compare the cytotoxicity of CH nanoparticles and conventional CH on fibroblast cell line using the Mosmann’s Tetrazolium Toxicity (MTT) assay. Methods and Materials: This study was conducted on L929 murine fibroblast cell line by cell culture and evaluation of the direct effect of materials on the cultured cells. Materials were evaluated in two groups of 10 samples each at 24, 48 and 72 h. At each time point, 10 samples along with 5 positive and 5 negative controls were evaluated. The samples were transferred into tubes and exposed to fibroblast cells. The viability of cells was then evaluated. The Two-way ANOVA was used for statistical analysis and the level of significance was set at 0.05. Results: Cytotoxicity of both materials decreased over time and for conventional CH was lower than that of nanoparticles. However, this difference was not statistically significant (P>0.05). Conclusion: The cytotoxicity of CH nanoparticles was similar to that of conventional CH. PMID:25598810

  12. Sodium-hydroxide solution treatment on sandstone cores

    SciTech Connect

    Lee, S.J.

    1984-01-01

    This research was performed to study the effect of sodium hydroxide solution on the sandstone core samples and to develop a method whereby the permeability of the samples could be increased by the injection of sodium hydroxide solution. This work should provide the first step in developing a technique that can be used in the stimulation of oil and gas wells. A series of tests was conducted in which sodium hydroxide solution with concentrations ranging from 0.25 N to 2.00 N was injected into a number of Berea sandstone cores. The tests were conducted at room temperature and at 180{degree}F. In some cases the core sample were damaged by the injection of fresh water which resulted in a marked reduction in the permeability of the cores prior to the injection of sodium hydroxide solution. Based on laboratory testing with measurements of uniaxial compressive strength, SEM examination and X-ray analysis, it was found that sodium hydroxide interacted with sandstone to promote (1) partial dissolution of the sandstone minerals; (2) sandstone weight loss; (3) increased porosity; (4) weakening of the sandstone cores; and (5) changes in permeability. The interaction increased with increasing temperature and increasing sodium hydroxide concentration. However, at concentrations higher than 1.00 N, the degree of increase in permeability was not as large even though the sandstone weight loss and the increase in porosity did increase.

  13. Comparison of Antifungal Activity of 2% Chlorhexidine, Calcium Hydroxide, and Nanosilver gels against Candida Albicans

    PubMed Central

    Mozayeni, Mohammad Ali; Hadian, Ali; Bakhshaei, Pedram; Dianat, Omid

    2015-01-01

    Objectives: Residual microorganisms in the root canal system (RCS) after endodontic therapy such as Candida albicans are a major cause of endodontic failure. Calcium hydroxide (CH) and chlorhexidine (CHX) have suitable antimicrobial activity against bacteria and can be used as intracanal medicaments. Nanosilver has also shown antimicrobial activity against microorganisms. This study aimed to compare the antifungal effect of calcium hydroxide, 2% chlorhexidine and nanosilver gels on Candida albicans. Materials and Methods: Eighty-one single-rooted teeth were selected. After root canal preparation, the teeth were contaminated. After culture, the teeth were randomly divided into 4 groups. In experimental groups, 24 teeth were selected and completely filled with CH, 2% CHX and nanosilver gels in each group. Nine teeth were selected in the control group and filled with saline solution. After 1, 3, and 7 days, samples were obtained by #30 sterile paper points, and #2 and #4 Gates Glidden drills and cultured on solid Sabouraud agar. Results: The results demonstrated that CH and 2% CHX had equal antifungal effects on samples taken by paper point and #2 Gates Glidden drill at all time points. Both CH and 2% CHX were more effective than nanosilver at all time periods. There was no statistically significant difference between medicaments in samples taken by #4 Gates Glidden drill. Conclusion: CH and 2% CHX gels have significantly higher antifungal activity than nanosilver gel. Also, CH and 2% CHX gels are equally effective against Candida albicans. PMID:26056520

  14. A titration model for evaluating calcium hydroxide removal techniques

    PubMed Central

    PHILLIPS, Mark; McCLANAHAN, Scott; BOWLES, Walter

    2015-01-01

    Objective Calcium hydroxide (Ca(OH)2) has been used in endodontics as an intracanal medicament due to its antimicrobial effects and its ability to inactivate bacterial endotoxin. The inability to totally remove this intracanal medicament from the root canal system, however, may interfere with the setting of eugenol-based sealers or inhibit bonding of resin to dentin, thus presenting clinical challenges with endodontic treatment. This study used a chemical titration method to measure residual Ca(OH)2 left after different endodontic irrigation methods. Material and Methods Eighty-six human canine roots were prepared for obturation. Thirty teeth were filled with known but different amounts of Ca(OH)2 for 7 days, which were dissolved out and titrated to quantitate the residual Ca(OH)2 recovered from each root to produce a standard curve. Forty-eight of the remaining teeth were filled with equal amounts of Ca(OH)2 followed by gross Ca(OH)2 removal using hand files and randomized treatment of either: 1) Syringe irrigation; 2) Syringe irrigation with use of an apical file; 3) Syringe irrigation with added 30 s of passive ultrasonic irrigation (PUI), or 4) Syringe irrigation with apical file and PUI (n=12/group). Residual Ca(OH)2 was dissolved with glycerin and titrated to measure residual Ca(OH)2 left in the root. Results No method completely removed all residual Ca(OH)2. The addition of 30 s PUI with or without apical file use removed Ca(OH)2 significantly better than irrigation alone. Conclusions This technique allowed quantification of residual Ca(OH)2. The use of PUI (with or without apical file) resulted in significantly lower Ca(OH)2 residue compared to irrigation alone. PMID:25760272

  15. Calcium hydroxide pulpotomy with a light-cured cavity-sealing material after two years.

    PubMed

    Gruythuysen, R J; Weerheijm, K L

    1997-01-01

    In this follow-up study a light-cured glass ionomer lining cement was evaluated as a cavity-sealing material in calcium hydroxide pulpotomies in primary molars after one and two years. The pulpotomy dressing was a suspension of pure calcium hydroxide with either tap water or sterile saline. The success rate of the pulpotomies after one year was 87.7 percent and after two years 80.4 percent (clinically and radiographically). This result was only influenced by the type of restoration (amalgam versus stainless steel crown). The results of the present investigation compare favorably with those of other published studies of pulpotomy of primary molars using calcium hydroxide as the wound dressing. PMID:9328675

  16. Simultaneous sulfur dioxide and nitrogen dioxide removal by calcium hydroxide and calcium silicate solids.

    PubMed

    Nelli, C H; Rochelle, G T

    1998-09-01

    At conditions typical of a bag filter exposed to a coal-fired flue gas that has been adiabatically cooled with water, calcium hydroxide and calcium silicate solids were exposed to a dilute, humidified gas stream of nitrogen dioxide (NO2) and sulfur dioxide (SO2) in a packed-bed reactor. A prior study found that NO2 reacted readily with surface water of alkaline and non-alkaline solids to produce nitrate, nitrite, and nitric oxide (NO). With SO2 present in the gas stream, NO2 also reacted with S(IV), a product of SO2 removal, on the exterior of an alkaline solid. The oxidation of S(IV) to S(VI) by oxygen reduced the availability of S(IV) and lowered removal of NO2. Subsequent acidification of the sorbent by the removal of NO2 and SO2 facilitated the production of NO. However, the conversion of nitrous acid to sulfur-nitrogen compounds reduced NO production and enhanced SO2 removal. A reactor model based on empirical and semi-empirical rate expressions predicted rates of SO2 removal, NO2 removal, and NO production by calcium silicate solids. Rate expressions from the reactor model were inserted into a second program, which predicted the removal of SO2 and NOx by a continuous process, such as the collection of alkaline solids in a baghouse. The continuous process model, depending upon inlet conditions, predicted 30-40% removal for NOx and 50-90% removal for SO2. These results are relevant to dry scrubbing technology for combined SO2 and NOx removal that first oxidizes NO to NO2 by the addition of methanol into the flue duct. PMID:9775761

  17. Nonsurgical management of large periapical lesion in mature and immature teeth using different calcium hydroxide formulations: case series.

    PubMed

    Kumar, G Vinay; Hegde, Reshma S; Moogi, Prashant P; Prashant, B R; Patil, Basanagouda

    2013-01-01

    This case series evaluates the effectiveness of different calcium hydroxide formulations with various vehicles in management of large periapical lesion in mature and immature teeth. This will help clinicians to make informed judgments about which formulations of calcium hydroxide should be used for specific endodontic procedures. PMID:24858773

  18. 75 FR 28608 - Calcium Hydroxide; Receipt of Application for Emergency Exemption, Solicitation of Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-21

    ... exemption request from the Hawaii Department of Agriculture to use the pesticide calcium hydroxide (CAS No... determines that emergency conditions exist which require the exemption. The Hawaii Department of Agriculture... as part of this request. As part of this request, the Hawaii Department of Agriculture asserts...

  19. [Comprehensive endodontic treatment with the use of depo- and galvanophoresis with copper hydroxide-calcium].

    PubMed

    Rumiantsev, V A; Opeshko, V V; Tubaeva, E A; Stapanian, Z V; Chakhkieva, F D; Kop'ev, D A; Ovcharenko, O S

    2007-01-01

    In the blind and randomized study in cases of routine endodontic treatment of 460 teeth in 372 patients high efficacy of additional use of depo- and galvanophoresis with copper hydroxide-calcium according to the technique modified by the authors. PMID:17828063

  20. Pseudo-hydroxide extraction in the separation of sodium hydroxide from aqueous solutions using alkyl phenols

    SciTech Connect

    Kang, Hyun Ah; Moyer, Bruce A

    2006-01-01

    Pseudo-hydroxide extraction of sodium hydroxide from aqueous solution using four alkyl phenols of nearly identical molecular weight in 1-octanol at 25 degrees C was examined to understand the effect of alkyl substituents. The order of extraction strength among the four alkyl phenols tested was 4-tert-octylphenol. 3,5-di-tertbutylphenol. 2,4-di-tert-butylphenol. 2,6-di-tert-butyl-4-methylphenol. A good correlation with phenol pK(a) was observed, indicating that extraction strength is determined by phenol acidity, as modified by steric effects in proximity to the phenol - OH group. The effective partition ratios (P-eff) of two phenols from 1 M NaOH solution were determined, showing that the phenols remain predominantly in the 1-octanol phase even when converted to their sodium salts. However, the hydrophobicity of the tested phenols may not be sufficient for process purposes. The equilibrium constants for the governing extraction equilibria were determined by modeling the data using the program SXLSQI, supporting the cation-exchange extraction mechanism. The proposed mechanism consists of two simple sets of equilibria for a. Ion-pair extraction to give Na+OH- ion pairs and corresponding free ions in 1-octanol the phase and b. Cation exchange by monomeric phenol molecules (HAs) to form monomeric organic-phase Na(+)A(-) ion pairs and corresponding free organic-phase ions.

  1. Comparative Performance of Mineral Trioxide Aggregate Versus Calcium Hydroxide as a Direct Pulp Capping Agent.

    PubMed

    Jefferies, Steven R

    2016-03-01

    Vital pulp therapy is the general concept involved in the "regenerative" restorative treatment of the reversibly injured dental pulp with the intention of maintaining its vitality in a restored, functioning tooth. While this procedure has been attempted with various materials and techniques over a period of several centuries, the advent of hard-setting calcium hydroxide materials in the late 1950s made the procedure of direct pulp capping a more routine and relatively predictable procedure. More recently, in the mid 1990s, a new type of water-based, "hydraulic-type," calcium silicate-based cement, mineral trioxide aggregate (MTA), was introduced to dentistry as a possible alternative to the established standard of hard-setting calcium hydroxide. Over the last two decades, a slowly growing body of pre-clinical and human clinical studies evaluating and comparing these two materials has developed. Most recently, a number of well-designed, randomized controlled studies and resultant systematic reviews have been completed and published regarding the comparative efficacy of calcium hydroxide versus MTA for direct pulp capping. This Critical Appraisal considers and reviews some of the more recently published reports which provide a more definitive answer to this clinical research question. PMID:26876369

  2. Alcohol dispersions of calcium hydroxide nanoparticles for stone conservation.

    PubMed

    Rodriguez-Navarro, Carlos; Suzuki, Amelia; Ruiz-Agudo, Encarnacion

    2013-09-10

    Alcohol dispersions of Ca(OH)2 nanoparticles, the so-called nanolimes, are emerging as an effective conservation material for the consolidation of stone, mortars, and plasters present in old masonry and/or mural paintings. To better understand how this treatment operates, to optimize its performance and broaden its applications, here we study the nano and microstructural characteristics, carbonation behavior, and consolidation efficacy of colloidal alcohol dispersions of Ca(OH)2 nanoparticles produced by both homogeneous (commercial nanolime) and heterogeneous phase synthesis (aged slaked lime and carbide lime putties). We observe that the alcohol not only provides a high colloidal stability to Ca(OH)2 particles, but also affects the kinetics of carbonation and CaCO3 polymorph selection. This is due to the pseudomorphic replacement of Ca(OH)2 particles by calcium alkoxides upon reaction with ethanol or 2-propanol. The extent of this replacement reaction depends on Ca(OH)2 size and time. Hydrolysis of alkoxides speeds up the carbonation process and increases the CaCO3 yield. The higher degree of transformation into calcium alkoxide of both the commercial nanolime and the carbide lime fosters metastable vaterite formation, while calcite precipitation is promoted upon carbonation of the aged slaked lime due its lower reactivity, which limits calcium alkoxide formation. A higher consolidation efficacy in terms of strength gain of treated porous stone is achieved in the latter case, despite the fact that the carbonation is much faster and reaches a higher yield in the former ones. Formation of alkoxides, which has been neglected in previous studies, needs to be considered when applying nanolime treatments. These results show that the use Ca(OH)2 nanoparticle dispersions prepared with either aged slaked lime or carbide lime putties is an economical and effective conservation alternative to commercial nanolimes produced by homogeneous phase synthesis. Ultimately, this

  3. Calcium hydroxide mixed with camphoric p-monochlorophenol or chlorhexidine in delayed tooth replantation.

    PubMed

    Trevisan, Carolina Lunardelli; Panzarini, Sônia Regina; Brandini, Daniela Atili; Poi, Wilson Roberto; Luvizuto, Eloá Rodrigues; Dos Santos, Cláudia Letícia Vendrame; Saito, Célia Tomiko Hamada Matida

    2011-11-01

    This study evaluated the repair process after delayed replantation of rat teeth, using calcium hydroxide (Ca(OH)2) mixed with camphorated p-monochlorophenol (CMCP), chlorhexidine 2% (CHX), or saline as temporary root canal dressing to prevent and/or control inflammatory radicular resorption. Thirty Wistar rats (Rattus norvegicus albinos) had their right upper incisor extracted, which was bench-dried for 60 minutes. The dental papilla, the enamel organ, the dental pulp, and the periodontal ligament were removed. The teeth were immersed in 2% acidulated-phosphate sodium fluoride solution for 10 minutes. The root canals were dried with absorbent paper cones and divided into 3 groups of 10 animals according to root canal dressing used: group 1: Ca(OH)2 + saline, group 2: Ca(OH)2 + CMCP, and group 3: Ca(OH)2 + CHX 2%. Before replanting, the teeth sockets were irrigated with saline. Histological analysis revealed the presence of inflammatory resorption, replacement resorption, and ankylosis in all 3 groups. Statistical analysis showed a significant difference between group 3 and the other groups. The use of Ca(OH)2 mixed with CMCP or CHX did not show an advantage over the use of Ca(OH)2 mixed with saline in preventing and/or controlling inflammatory resorption in delayed replantation of rat teeth. PMID:22067873

  4. Anaerobic tissue-dissolving abilities of calcium hydroxide and sodium hypochlorite.

    PubMed

    Yang, S F; Rivera, E M; Baumgardner, K R; Walton, R E; Stanford, C

    1995-12-01

    Closed root canals likely have an oxygen-free environment; most bacteria in canals are anaerobic. These bacteria and other debris are difficult to remove. Unknown is tissue dissolution with chemicals under these anaerobic conditions. This study evaluated and compared dissolving properties of calcium hydroxide (Ca(OH)2) and sodium hypochlorite (NaOCl) on bovine pulp tissue in aerobic and anaerobic environments. Sixty bovine pulp specimens were dried, then randomly divided into six groups. Groups A and B were immersed in Ca(OH)2 + water solution, whereas group C and D were in 2.5% NaOCl. Groups E and F (controls) specimens were placed in distilled water. Groups A, C, and E were incubated anaerobically, and groups B, D, and F were incubated under regular atmospheric conditions, all for 7 days. Percentages of weight loss were compared between groups. Results showed the following: (a) both chemicals partially dissolved pulp tissue, (b) anaerobic environment did not alter tissue-dissolving properties of Ca(OH)2 or NaOCl, and (c) Ca(OH)2 and NaOCl were equal and more effective than water. PMID:8596083

  5. The use of calcium hydroxide, antibiotics and biocides as antimicrobial medicaments in endodontics.

    PubMed

    Athanassiadis, B; Abbott, P V; Walsh, L J

    2007-03-01

    Bacteria have been implicated in the pathogenesis and progression of pulp and periapical diseases. The primary aim of endodontic treatment is to remove as many bacteria as possible from the root canal system and then to create an environment in which any remaining organisms cannot survive. This can only be achieved through the use of a combination of aseptic treatment techniques, chemomechanical preparation of the root canal, antimicrobial irrigating solutions and intracanal medicaments. The choice of which intracanal medicament to use is dependent on having an accurate diagnosis of the condition being treated, as well as a thorough knowledge of the type of organisms likely to be involved and their mechanisms of growth and survival. Since the disease is likely to have been caused by the presence of bacteria within the root canal, the use of an antimicrobial agent is essential. Many medicaments have been used in an attempt to achieve the above aims but no single preparation has been found to be completely predictable or effective. Commonly used medicaments include calcium hydroxide, antibiotics, non-phenolic biocides, phenolic biocides and iodine compounds. Each has advantages and disadvantages, and further research is required to determine which is best suited for root canal infections. PMID:17546863

  6. Carbonation as a binding mechanism for coal/calcium hydroxide pellets. [Quarterly] technical report, March 1, 1993--May 31, 1993

    SciTech Connect

    Lytle, J.; Hackley, K.; Dagamac, M.; Berger, R.; Schanche, G.

    1993-09-01

    This research is an investigation of calcium hydroxide, a sulfur-capturing sorbent, as a binder for coal fines. The reaction of carbon dioxide with calcium hydroxide, referred to as carbonation, is being studied as a method of improving pellet quality. Carbonation forms a cementitious matrix of calcium carbonate. The effect of particle size and compaction pressure on pellet strength was studied using a laboratory hydraulic press. Particle distributions with mean sizes of 200, 90 and 40 microns were tested. The results indicate that pellet strength increased with decreasing particle size and increasing compaction pressure when calcium hydroxide was used as a binder. Pellets containing 10 wt% calcium hydroxide increased in strength by approximately 40% when air dried for one day. This increase in strength is attributed to carbonation of the calcium hydroxide via atmospheric carbon dioxide. Corn starch, an adhesive binder, was tested at the finest particle size. Pellet strength did not increase as a function of increasing compaction pressure. At the finest particle size and highest compaction pressure (18,750 psi), dried pellets formed with 2 wt% corn starch were equivalent in strength to pellets containing 5 wt% calcium hydroxide.

  7. Efficacy of the NaviTip FX irrigation needle in removing calcium hydroxide from root canal

    PubMed Central

    Bramante, Clovis M.; Pinheiro, Bethânia C.; Garcia, Roberto B.; Bramante, Alexandre S.; Bernardineli, Norberti; de Moraes, Ivaldo G.; Húngaro-Duarte, Marco A.

    2012-01-01

    Objective: To evaluate the effectiveness of the NaviTip FX, brush-covered irrigation needle, in removing calcium hydroxide from the root canal. Study Design: Thirty single-rooted teeth were randomly divided into three groups: A - irrigation with a hypodermic needle inserted as far as possible without binding and activation with #30 K-type file; B - Irrigation with a hypodermic needle without activation; C - irrigation with NaviTip FX needle. Sodium hypoclorite 1% was used in irrigation. The root canals were examined trough scanning electron microscopy. Calcium hydroxide removal was recorded at 1, 5, and 10mm from the working length (WL) and the data were analysed using one-way ANOVA test (p<0.05). Results: NaviTip FX and hypodermic needle activated with #30K-type file showed lower score at 10 and 5mm with no significant difference between them. Comparison within groups did not show significant differences. All groups showed significantly better smear layer removal at 5 and 10 mm from the WL. Conclusion: The apical third (1mm) of the root canal was found to be the most critical site for Ca(OH)2 removal. Key words:Calcium hydroxide, irrigation, scanning electron microscope, NaviTip FX. PMID:24558560

  8. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    DOEpatents

    Rau, Gregory Hudson

    2012-05-15

    A system is described for forming metal hydroxide from a metal carbonate utilizing a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate, in particular water-insoluble calcium carbonate or magnesium carbonate, is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide. Among other uses, the metal hydroxide formed can be employed to absorb acid gases such as carbon dioxide from a gas mixture. The invention can also generate hydrogen and oxidative gases such as oxygen or chlorine.

  9. Clinical outcome of direct pulp capping with MTA or calcium hydroxide: a systematic review and meta-analysis

    PubMed Central

    Zhu, Chenxi; Ju, Bin; Ni, Rong

    2015-01-01

    Direct pulp capping is one of the most common dental practices in endodontic therapy. This systematic review and meta-analysis aim to determine whether the effect of mineral trioxide aggregate (MTA) and calcium hydroxide for direct pulp capping is different, as measured by the clinical and radiographic analysis. The study list was obtained by searching PubMed, Springer Link, Scopus and Cochrane Database. Only those papers that met the inclusion criteria were analyzed. The results indicated that four studies met the inclusion criteria. Statistically significant difference was found between the success rates of MTA and calcium hydroxide treated teeth that needed direct pulp capping (P=0.002). Clinical assessments of the MTA versus calcium hydroxide for direct pulp capping suggested that MTA was superior to calcium hydroxide in direct pulp capping resulting in a lower failure rate (risk difference 0.1 [95% CI 0.04 to 0.16]). In conclusion, MTA has a higher clinical success rate for direct pulp capping comparing to calcium hydroxide, and might be a suitable replacement for calcium hydroxide. PMID:26770296

  10. Ions Release and pH of Calcium Hydroxide-, Chlorhexidine- and Bioactive Glass-Based Endodontic Medicaments.

    PubMed

    Carvalho, Ceci Nunes; Freire, Laila Gonzales; Carvalho, Alexandre Pinheiro Lima de; Duarte, Marco Antonio Húngaro; Bauer, José; Gavini, Giulio

    2016-01-01

    This study evaluated pH and release of calcium, sodium and phosphate ions from different medications in human dentin. Fifty premolars were prepared and randomly divided into groups: (CHX) - 2% chlorhexidine gel; (CHX + CH) - CHX + calcium hydroxide PA; (CH) - CH + propylene glycol 600; (NPBG) - experimental niobium phosphate bioactive glass + distilled water; (BG) - bioactive glass (Bio-Gran) + distilled water. The specimens were immersed in deionized water and the pH variations were measured. The quantification of ions in the solutions was made by inductively coupled plasma - atomic emission spectroscopy (ICP/AES) at 10 min, 24 h, 7, 14, 21 and 30 days. The results were analyzed by ANOVA and Tukey`s test, with a significance level of 5%. CH had the highest level of calcium ions release at 30 days, while CHX and BG released more sodium ions. BG, NPBG and CHX released a higher amount of phosphate ions. The pH of CH was significantly higher compared with the other groups. CH favored the greatest increase of pH and calcium ions release. The bioactive glasses released more sodium and phosphate ions and presented an alkaline pH immediately and after 30 days. PMID:27224568

  11. Coprecipitation with calcium hydroxide for determination of iron in fish otoliths by collision cell ICP-MS.

    PubMed

    Daniels, Stephanie L; Arslan, Zikri

    2007-05-01

    A method has been described for the determination of iron from fish otoliths containing high levels of calcium by collision cell technology (CCT) ICP-MS. Iron (Fe) in otolith solutions was quantitatively coprecipitated with small amounts of calcium hydroxide by adding 1.0 M sodium hydroxide solution. The performance of CCT-ICP-MS pressurized with He/H(2) cell gas was investigated on the elimination of Ca-based spectral interferences at m/z 54, 56 and 57. Molecular ion interferences at m/z 54 and 56 were reduced by 2 orders of magnitude. However, the interferences at m/z 57 increased by the same amount in the presence of Ca in solutions owing to the formation of (40)Ca(16) OH(+) through reactions with H(2) in collision cell, indicating that (57)Fe was not suitable for the determination of Fe from otoliths. Results for (56)Fe suffered significantly from interferences of Ca-based molecular ions when the Ca concentration in solution exceeded 100 microg ml(-1), for which matrix-matched calibration was required for accurate determination. CCT with the aid of He/H(2) cell gas proved to be very effective in eliminating the interferences ((40)Ar(14)N(+) and (40)Ca(14)N(+)) at m/z 54. Presence of Ca up to 300 microg ml(-1) had virtually no effect on the ion signals of (54)Fe, which with low background signals, afforded accurate determination of Fe from otoliths by using aqueous external standards. PMID:17294508

  12. METHOD FOR RECOVERING PLUTONIUM VALUES FROM SOLUTION USING A BISMUTH HYDROXIDE CARRIER PRECIPITATE

    DOEpatents

    Faris, B.F.

    1961-04-25

    Carrier precipitation processes for separating plutonium values from aqueous solutions are described. In accordance with the invention a bismuth hydroxide precipitate is formed in the plutonium-containing solution, thereby carrying plutonium values from the solution.

  13. Carbonation acceleration of calcium hydroxide nanoparticles: induced by yeast fermentation

    NASA Astrophysics Data System (ADS)

    Lopez-Arce, Paula; Zornoza-Indart, Ainara

    2015-09-01

    Carbonation of Ca(OH)2 nanoparticles and consolidation of limestone are accelerated by high humidity and a yeast fermentation system that supplies a saturated atmosphere on CO2, H2O vapor and ethanol during 28 days. Nanoparticles were analyzed by X-ray diffraction and differential thermal analyses with thermogravimetry. Spectrophotometry, scanning electron microscopy analyses, and hydric and mechanical tests were also performed in stones specimens. Samples exposed to the yeast environment achieve 100 % relative CaCO3 yield, whereas at high humidity but without the yeast and under laboratory environment, relative yields of 95 % CaCO3 and 15 % CaCO3 are, respectively, reached, with white crusts and glazing left on the stone surfaces when the nanoparticles are applied at a concentration of 25 g/l. The largest increase in the drilling resistance and surface hardness values with slight increase in the capillarity absorption and desorption coefficients and with lesser stone color changes are produced at a concentration of 5 g/l, in the yeast system environment. This especially happens in stone specimens initially with bimodal pore size distributions, more amounts of pores with diameters between 0.1 and 1 µm, higher open porosity values and faster capillary coefficients. An inexpensive and reliable method based on water and yeast-sugar solution is presented to speed up carbonation of Ca(OH)2 nanoparticles used as a consolidating product to improve the mechanical properties of decayed limestone from archaeological and architectural heritage.

  14. Effects of calcium hydroxide addition on the physical and chemical properties of a calcium silicate-based sealer

    PubMed Central

    KUGA, Milton Carlos; DUARTE, Marco Antonio Hungaro; SANT'ANNA-JÚNIOR, Arnaldo; KEINE, Kátia Cristina; FARIA, Gisele; DANTAS, Andrea Abi Rached; GUIOTTI, Flávia Angélica

    2014-01-01

    Recently, various calcium silicate-based sealers have been introduced for use in root canal filling. The MTA Fillapex is one of these sealers, but some of its physicochemical properties are not in accordance with the ISO requirements. Objective The aim of this study was to evaluate the flowability, pH level and calcium release of pure MTA Fillapex (MTAF) or containing 5% (MTAF5) or 10% (MTAF10) calcium hydroxide (CH), in weight, in comparison with AH Plus sealer. Material and Methods The flowability test was performed according to the ISO 6876:2001 requirements. For the pH level and calcium ion release analyses, the sealers were placed individually (n=10) in plastic tubes and immersed in deionized water. After 24 hours, 7 and 14 days, the water in which each specimen had been immersed was evaluated to determine the pH level changes and calcium released. Flowability, pH level and calcium release data were analyzed statistically by the ANOVA test (α=5%). Results In relation to flowability: MTAF>AH Plus>MTAF5>MTAF10. In relation to the pH level, for 24 h: MTAF5=MTAF10=MTAF>AH Plus; for 7 and 14 days: MTAF5=MTAF10>MTAF>AH Plus. For the calcium release, for all periods: MTAF>MTAF5=MTAF10>AH Plus. Conclusions The addition of 5% CH to the MTA Fillapex (in weight) is an alternative to reduce the high flowability presented by the sealer, without interfering in its alkalization potential. PMID:25025558

  15. Carbonation as a binding mechanism for coal/calcium hydroxide pellets. Final technical report, 1 September, 1992--31 August, 1993

    SciTech Connect

    Rapp, D.; Lytle, J.; Hackley, K.; Dagamac, M.; Berger, R.; Schanche, G.

    1993-12-31

    This research was an investigation of calcium hydroxide, a sulfur-capturing sorbent, as a binder for coal fines. The reaction of carbon dioxide with calcium hydroxide, referred to as carbonation, was studied as a method for improving pellet quality. Carbonation forms a cementitious matrix of calcium carbonate. Research has demonstrated that calcium hydroxide is a viable binder for coal fines and that a roller-and-die pellet mill is an effective method of pellet formation. From a minus 28 mesh preparation plant fine coal sample, a roller-and-die pellet mill produced strong pellets when 5 and 10% calcium hydroxide was used as a binder. The pellets containing 10% calcium hydroxide strengthened considerably when air cured. This increase in strength was attributed to carbonation via atmospheric carbon dioxide. Pellets containing 10 wt% calcium hydroxide were produced using an extruder but pellets formed in this manner were much weaker than pellets produced with the roller-and-die mill. In tests performed using a laboratory hydraulic press, the effect of particle size and compaction pressure on pellet strength was studied. Particle distributions with mean sizes of 200, 90 and 40 microns were tested. The results indicate that pellet strength increased with decreasing particle size and increasing compaction pressure when calcium hydroxide was used as a binder. Pellets containing 10 wt% calcium hydroxide increased in strength by approximately 40% when air dried for one day. As above, this increase in strength was attributed to carbonation of the calcium hydroxide via atmospheric carbon dioxide.

  16. Cellulose aerogels from aqueous alkali hydroxide-urea solution.

    PubMed

    Cai, Jie; Kimura, Satoshi; Wada, Masahisa; Kuga, Shigenori; Zhang, Lina

    2008-01-01

    Highly porous and strong cellulose aerogels were prepared by gelation of cellulose from aqueous alkali hydroxide/urea solution, followed by drying with supercritical CO2. Their morphology, pore structure, and physical properties were characterized by scanning and transmission electron microscopy, X-ray diffraction, nitrogen adsorption measurements, UV/Vis spectrometry, and tensile tests. The cellulose hydrogel was composed of interconnected about 20 nm wide. By using supercritical CO2 drying, the network structure in the hydrogel was well preserved in the aerogel. The results are preliminary but demonstrate the ability of this method to give cellulose aerogels of large surface areas (400-500 m2 g(-1)) which may be useful as adsorbents, heat/sound insulators, filters, catalyst supports, or carbon aerogel precursors. PMID:18605678

  17. Efficacy of different techniques for removal of calcium hydroxide-chlorhexidine paste from root canals.

    PubMed

    Camargo, Carlos Henrique Ribeiro; Leal, Flávia Martins; Silva, Gleyce Oliveira; de Oliveira, Tatiana Rocha; Madureira, Paloma Grasso; Camargo, Samira Esteves Afonso

    2016-01-01

    The purpose of this study was to evaluate the efficacy of different techniques for removal of combined calcium hydroxide [Ca(OH)2] and chlorhexidine paste from root canals. Fifty single-rooted human teeth were prepared by oscillatory and rotary systems and filled with a paste of Ca(OH)2 and 2% chlorhexidine gel. After incubation for 14 days, the specimens were divided into 5 groups (n = 10), and the medication was removed by 1 of 5 different procedures. In group 1 (control), removal procedures involved a master apical file, foraminal debridement, and 5 mL of saline solution applied with the NaviTip irrigation needle. Group 2 was treated the same as group 1, but in addition 0.5 mL of 17% ethylenediaminetetraacetic acid was used for 3 minutes. In group 3, ultrasonic agitation was performed for 1 minute. Group 4 was treated as group 2, but the NaviTip FX needle was used for irrigation. In group 5, a master apical file, foraminal debridement, and 3-minute application of 5 mL of citric acid were used. After the root-cleaning procedures, the crowns were removed at the cementoenamel junction, and the roots were split longitudinally into halves. The success of intracanal medicament removal was observed under stereoscopic microscope and scanning electron microscope. Remnants of Ca(OH)2 were found in all experimental groups, regardless of the removal technique used. There was no statistically significant difference in cleanliness in the apical third of the root canal among groups 1, 2, and 3. Group 4 showed the best and group 5 the worst results with statistically significant differences. Overall, the NaviTip FX irrigation needle technique was more efficient in removing a Ca(OH)2-chlorhexidine paste from the root canal. PMID:26943099

  18. 40 CFR 721.10018 - Calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Calcium hydroxide oxide silicate (Ca6... New Uses for Specific Chemical Substances § 721.10018 Calcium hydroxide oxide silicate (Ca6(OH)2O2... substance identified as calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3) (PMN P-01-442; CAS No....

  19. 40 CFR 721.10018 - Calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Calcium hydroxide oxide silicate (Ca6... New Uses for Specific Chemical Substances § 721.10018 Calcium hydroxide oxide silicate (Ca6(OH)2O2... substance identified as calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3) (PMN P-01-442; CAS No....

  20. [Effects of the treatment of coffee pulp, fresh or ensilaged, with calcium hydroxide, on its nutritive value].

    PubMed

    Gómez-Brenes, R; Bendaña, G; González, J M; Jarquín, R; Braham, J E; Bressani, R

    1988-03-01

    This study was carried out to determine the effects of the addition of calcium hydroxide on the chemical composition and nutritive value of fresh or ensilaged coffee pulp. Fresh or ensilaged pulp were mixed with 1, 2 and 3% of calcium hydroxide. The process was carried out during 0 and 16 hr, after which time the treated pulp was sun-dried for 36 hr until moisture content reached 12%. These samples were then analyzed for their proximate chemical composition and for some minerals (Ca, P, Na, K), as well as for caffeine, tannins and chlorogenic and caffeic acids content. Diets were then prepared from these materials, containing 15% protein and 15 or 30% fresh or ensilaged coffee pulp, and offered to weanling rats during six weeks. Information required on weight gain, food conversion, apparent digestibility and toxicity of the diets was recorded. Results of the chemical analysis revealed that the main changes found in both types of pulp as a result of the calcium hydroxide treatment were the following: a decrease in ether extract (from 4.0 to 2.5 g/100 g), crude fiber (from 18.3 to 11.9 g/100 g) and protein content (from 12.3 to 8.6 g/100 g) in an inverse relation to the amount of calcium hydroxide used. The amount of ash increased, fluctuated between 5.5 and 15.4%, depending on the amount of calcium hydroxide used. The latter affected the Ca:P ratio in the diets, where an average ratio of 7.2:1 was found in the control pulp (0% calcium hydroxide) and 59.0:1 in those treated with the highest amount of calcium hydroxide (3%). Regarding the caffeine, tannins and chlorogenic and caffeic acids contents, calcium hydroxide was effective in decreasing only tannins, more so in the fresh than in the ensilaged pulp; the decrease was in direct proportion to the amount of calcium hydroxide added and to the length of the Ca(OH)2 treatment. The results of the biological assays showed that the addition of Ca(OH)2 in either of the two time periods used and at either of the

  1. [Study of some physical and biological properties of an endodontic sealer composed of calcium hydroxide].

    PubMed

    Birman, E G; Sampaio, J M; Magalhães, J; Sato, E

    1990-01-01

    The authors present a study of the physical and biological properties of a new endodontic cement known as Sealapex. In its composition the presence of calcium hydroxide is introduced in order to induce calcification of the periapical tissue. Our results using glass round cover slips implanted on the subcutaneous tissue of mice indicated a persistent foreign body reaction (60 days). The physical properties studied compared to N-Rickert ciment indicated, a decreased leakage. Adhesivity tests didn't give us significant values. Laboratorial studies and clinical trials are necessary to a complete acceptance of this new ciment in endodontic treatment. PMID:2135327

  2. Improving the quality of rice straw by urea and calcium hydroxide on rumen ecology, microbial protein synthesis in beef cattle.

    PubMed

    Polyorach, S; Wanapat, M

    2015-06-01

    Four rumen-fistulated beef cattle were randomly assigned to four treatments according to a 4 × 4 Latin square design to study the influence of urea and calcium hydroxide [Ca(OH)2 ] treatment of rice straw to improve the nutritive value of rice straw. Four dietary treatments were as follows: untreated rice straw, 50 g/kg urea-treated rice straw, 20 g/kg urea + 20 g/kg calcium hydroxide-treated rice straw and 30 g/kg urea + 20 g/kg calcium hydroxide-treated rice straw. All animals were kept in individual pens and fed with concentrate at 0.5 g/kg of BW (DM), rice straw was fed ad libitum. The experiment was conducted for four periods, and each period lasted for 21 days. During the first 14 days, DM feed intake measurements were made while during the last 7 days, all cattle were moved to metabolism crates for total faeces and urine collections. The results revealed that 20 g/kg urea + 20 g/kg calcium hydroxide-treated rice straw improved the nutritive value of rice straw, in terms of dry matter intake, digestibility, ruminal volatile fatty acids, population of bacteria and fungi, nitrogen retention and microbial protein synthesis. Based on this study, it could be concluded that using urea plus calcium hydroxide was one alternative method to improve the nutritive value of rice straw, rumen ecology and fermentation and thus a reduction of treatment cost. PMID:25244259

  3. Form and stability of aluminum hydroxide complexes in dilute solution

    USGS Publications Warehouse

    Hem, John David; Roberson, Charles Elmer

    1967-01-01

    Laboratory studies of solutions 4.53 x 10 -4 to 4.5 x 10 -5 molal (12.2-1.2 ppm) in aluminum, in 0.01 molal sodium perchlorate, were conducted to obtain information as to the probable behavior of aluminum in natural water. When the solutions were brought to pH 7.5-9.5 and allowed to stand for 24 hours, a precipitate was obtained which was virtually amorphous as shown by X-rays, and which had a solubility equivalent to that of boehmite. This precipitate had a hydrolysis constant (*Ks4) of 1.93 x 10 -13a. When solutions were allowed to stead at this pH range for 10 days, their precipitates gave the X-ray pattern of bayerite (*Ks4 = 1.11 > (10- 4). These hydrolysis constants were obtained at 25?C. and corrected to zero ionic strength and are in close agreement with other published values. The predominant dissolved form in this pH range is Al(OH) -4. Below neutral pH (7.0) the dissolved aluminum species consist of octahedral units in which each aluminum ion is surrounded by six water molecules or hydroxide ions. Single units such as Al(OH2)6 + 3 and AlOH(OH2)5+2 are most abundant below pH 5.0, and where the molar ratio (r) of combined hydroxide to total dissolved aluminum is low. When r is greater than 1.0, polymerization of the octahedral units occurs. When r is between 2.0 and 3.0, solutions aged for 10 days or more contained colloidal particles between 0.10 and 0.45 ? in diameter. Particles whose diameters were greater than 0.10 ? were identified by X-ray diffraction as gibbsite. Particles smaller than 0.10 ? were also present and were shown by means of the electron microscope to have a hexagonal crystal pattern. Structured material consisting of sheets of coalesced six-membered rings of aluminum ions held together by double OH bridges has a distinctive kinetic behavior. This property was used to determine amounts of polymerized material in solutions having r between 1.0 and 3.0 after aging times ranging from a few hours to more than 4 months. Aging increased the

  4. Absorption of chlorine into aqueous bicarbonate solutions and aqueous hydroxide solutions

    SciTech Connect

    Ashour, S.S.; Rinker, E.B.; Sandall, O.C.

    1996-03-01

    Removal of chlorine from certain gas streams may be of industrial importance for certain chemical processes. The absorption of Cl{sub 2} into aqueous bicarbonate and aqueous hydroxide solutions was studied both experimentally and theoretically. The rate coefficient of the reaction between Cl{sub 2} and OH{sup {minus}} was estimated over the temperature range of 293--312 K and fitted by the Arrhenius equation: k{sub 24} = 3.56 {times} 10{sup 11} exp({minus}1,617/T). If Cl{sub 2} were assumed to react only with water and OH{sup {minus}} in an aqueous bicarbonate solution, the predicted absorption rate would be much lower than that experimentally measured. This suggests that Cl{sub 2} reacts with HCO{sub 3}{sup {minus}} in an aqueous bicarbonate solution. The rate coefficient of the reaction between Cl{sub 2} and HCO{sub 3}{sup {minus}} was estimated over the temperature range of 293--313 K and fitted by the Arrhenius equation: k{sub 21} = 5.63 {times} 10{sup 10} exp({minus}4,925/T). More importantly, under absorption conditions, the amount of hydroxide consumed for absorbing a specific amount of Cl{sub 2} into an aqueous hydroxide solution is almost twice the amount of bicarbonate consumed for absorbing the same amount of Cl{sub 2} into an aqueous bicarbonate solution.

  5. Concentration of hydrogen ions in several calcium hydroxide pastes over different periods of time.

    PubMed

    Vianna, Morgana Eli; Zilio, Danila M; Ferraz, Caio Cezar Randi; Zaia, Alexandre Augusto; de Souza-Filho, Francisco José; Gomes, Brenda Paula Figueiredo de Almeida

    2009-01-01

    The purpose of this in vitro study was to measure the concentration of hydrogen ions (pH) of calcium hydroxide [(Ca(OH)2] pastes combined with different vehicles over 7 periods of time. The Ca(OH)2 was manipulated with the following vehicles: i: sterile water; ii: iodoform plus sterile water; iii: local anesthetics (Lydocaine 2% with 1: 100,000 epinephrine); iv: polyethyleneglycol; v: glycerin; vi: 2.0% chlorhexidine gel; vii: camphorated paramonochlorophenol (CMCP); viii: (CMCP) + glycerin; and ix: polyethyleneglycol plus CMCP. The pastes were made on a glass plate to toothpaste consistency and the pH was measured at the following times: 5 min, 1, 24, 48 h; 7, 14 and 28 days. The data were statistically analyzed (Kruskal-Wallis at p<0.05). At 5 min, 1 and 24 h, the pH of all tested pastes ranged from 13.05 to 11.16. At 48 h and 7 days the pH of all tested pastes ranged from 11.66 to 8.92. At 14 and 28 days almost all pastes had pH means lower than 10. In conclusion, the mean pH of all tested calcium hydroxide pastes decreased with the time. Pastes made with aqueous vehicles (especially with sterile water), followed by oily vehicles (especially with CMCP + glycerin), held the highest pH means over the periods of time tested. PMID:20126906

  6. Calcium sulphate in ammonium sulphate solution

    USGS Publications Warehouse

    Sullivan, E.C.

    1905-01-01

    Calcium sulphate, at 25?? C., is two-thirds as soluble in dilute (o.i mol per liter) and twice as soluble in concentrated (3 mois per liter) ammonium sulphate solution as in water. The specific electric conductivity of concentrated ammonium sulphate solutions is lessened by saturating with calcium sulphate. Assuming that dissociation of ammonium sulphate takes place into 2NH4?? and SO4" and of calcium sulphate into Ca and SO4" only, and that the conductivity is a measure of such dissociation, the solubility of calcium sulphate in dilute ammonium sulphate solutions is greater than required by the mass-law. The conductivity of the dilute mixtures may be accurately calculated by means of Arrhenius' principle of isohydric solutions. In the data obtained in these calculations, the concentration of non-dissociated calcium sulphate decreases with increasing ammonium sulphate. The work as a whole is additional evidence of the fact that we are not yet in possession of all the factors necessary for reconciling the mass-law to the behavior of electrolytes. The measurements above described were made in the chemical laboratory of the University of Michigan.

  7. Corrosion of zirconium alloys in concentrated lithium hydroxide solutions

    NASA Astrophysics Data System (ADS)

    Müller, S.; Lanzani, L.

    2013-08-01

    The accelerated corrosion of two alloys used as fuel cladding material, such as Zircaloy-4 and Zr-1%Nb has been studied in concentrated lithium hydroxide (LiOH) solutions at high temperature and pressure. Zr-2.5%Nb pressure tube material (PT) was also tested in order to analyze the influence of the amount of β-Zr phase on the accelerated corrosion of the Zr-Nb alloys. The microstructure of Zircaloy-4 consisted of α-Zr equiaxed grains whereas that of Zr-2.5%Nb (PT) and Zr-1%Nb alloys showed a two phase (α-Zr + β-Zr) microstructure. Autoclaving tests were performed in LiOH solutions with concentrations ranging from 0.1 M to 1 M for 16 h at 343 °C, and also in steam at 400 °C. The extent of corrosion was evaluated through the weight gain and visual appearance of the oxide. Measurements included hydrogen uptake and oxide thickness. Optical microscopy observations of the hydride distribution were also made on the specimens. Results showed that Zircaloy-4 suffered accelerated corrosion at 0.7 M and 1 M LiOH concentrations with high hydrogen uptakes (˜50%). For these LiOH concentrations, although the Zr-2.5%Nb (PT) and Zr-1%Nb alloys showed weight gains higher than the threshold value established for the "transition", their hydrogen uptakes were low (˜1%). This behavior indicates that at the early stages of the corrosion process in these solutions, an oxide barrier layer may be present at the metal/oxide interface of these Zr-Nb alloys. The lower amount of β-Zr phase in Zr-1%Nb improves the characteristics of the oxide layer in relation to that formed on Zr-2.5%Nb and does not affect the hydrogen uptake.

  8. Application of the SCC-DFTB method to hydroxide water clusters and aqueous hydroxide solutions.

    PubMed

    Choi, Tae Hoon; Liang, Ruibin; Maupin, C Mark; Voth, Gregory A

    2013-05-01

    The self-consistent charge density functional tight binding (SCC-DFTB) method has been applied to hydroxide water clusters and a hydroxide ion in bulk water. To determine the impact of various implementations of SCC-DFTB on the energetics and dynamics of a hydroxide ion in gas phase and condensed phase, the DFTB2, DFTB2-γ(h), DFTB2-γ(h)+gaus, DFTB3-diag, DFTB3-diag+gaus, DFTB3-Full+gaus, and DFTB3-3OB implementations have been tested. Energetic stabilities for small hydroxide clusters, OH(-)(H2O)n, where n = 4-7, are inconsistent with the results calculated with the B3LYP and second order Møller-Plesset (MP2) levels of ab initio theory. The condensed phase simulations, OH(-)(H2O)127, using the DFTB2, DFTB2-γ(h), DFTB2-γ(h)+gaus, DFTB3-diag, DFTB3-diag+gaus, DFTB3-Full+gaus and DFTB3-3OB methods are compared to Car-Parrinello molecular dynamics (CPMD) simulations using the BLYP functional. The SCC-DFTB method including a modified O-H repulsive potential and the third order correction (DFTB3-diag/Full+gaus) is shown to poorly reproduce the CPMD computational results, while the DFTB2 and DFTB2-γ(h) method somewhat more closely describe the structural and dynamical nature of the hydroxide ion in condensed phase. The DFTB3-3OB outperforms the MIO parameter set but is no more accurate than DFTB2. It is also shown that the overcoordinated water molecules lead to an incorrect bulk water density and result in unphysical water void formation. The results presented in this paper point to serious drawbacks for various DFTB extensions and corrections for a hydroxide ion in aqueous environments. PMID:23566052

  9. CALCIUM HYDROXIDE AND CALCIUM CARBONATE PARTICLE SIZE EFFECTS ON REACTIVITY WITH SULFUR DIOXIDE

    EPA Science Inventory

    The paper reports results of measurements of the effect of in situ calcium-based sorbent particle size upon reactivity with 3000 ppm SO2 in an 1100 c drop-tube furnace, using on-line collection of the reacted sorbent with a particle cascade impactor. Significant agglomeration occ...

  10. The Influence of Dentine on the pH of Calcium Hydroxide, Chlorhexidine Gel, and Experimental Bioactive Glass-Based Root Canal Medicament

    PubMed Central

    Nunes Carvalho, Ceci; Gonzales Freire, Laila; Pinheiro Lima de Carvalho, Alexandre; Luiz Siqueira, Evandro; Bauer, José; Cunha Gritti, Giovana; Pereira de Souza, Juliana; Gavini, Giulio

    2015-01-01

    Objectives. To evaluate the influence of dentine on the pH of different medications in standardized simulated canals. Materials and Methods. Forty resin blocks were divided into groups with and without dentine powder, as follows: 2% chlorhexidine gel; 2% chlorhexidine gel associated with calcium hydroxide PA; calcium hydroxide PA delivered in propylene glycol 600; and NPG delivered in distilled water. The dentine powder was obtained from the root dentine of bovine teeth and added to the medications. The simulated canals were placed in containers with 1.5 mL of deionized water and pH was monitored in multiple intervals, up to 30 days. The mean pH values were calculated and submitted to statistical analysis using paired Student's t-test and ANOVA complemented by the Tukey test (p < 0.05). Results. There was no statistical difference between the groups with and without dentine powder (p > 0.05). The pH values of calcium hydroxide were significantly higher than those of NPG in the first 24 hours (p < 0.05). After 7 days, both behaved in a similar manner. Conclusion. The addition of dentine powder to the medications evaluated did not alter the pH of the external solution in any of the time points tested. PMID:26347249

  11. [Growth and metabolism of calcium in rats chronically poisoned with aluminium hydroxide].

    PubMed

    Mahieu, S; Calvo, M L; Millen, N; Gonzalez, M; Contini, M C

    1998-01-01

    The effects of aluminum on growth have been studied in rats chronically poisoned with aluminum hydroxide (80 mg/kg b.w.-i.p.-three times a week, during 6 months) and in control rats, between 3 and 26 weeks of age. The growth data was evaluated according to Parks 'theory of feeding an growth. At the end of the poisoning period, the calcium metabolism was studied through a balance of calcium and the determination of bone Ca++ accretion and resorption rates with the aid of 45Ca++. The parathyroid glands function was studied using an indirect method. Treated rats showed a significant decrease in asymptotic weights and in the initial efficiency of food conversion into biomass regarding controls. No differences were observed in food intake between both group. Aluminum affected neither the peak growth rate nor the time necessary to attain maturity. The calcium balance in treated rats was significantly less than in the control group. This was accompanied by a significant increase in the calcium excreted by faces, caused perhaps by a less intestinal absorption. An important amount of aluminum on the surface of the trabecular bone and a reduction in the skeletal Ca++ mass, was observed in all treated rats. Nevertheless there are no differences in the latter when expressed for 100 g of body weight. The rate of skeletal Ca++ accretion was found to be significantly decreased in treated group with respect to controls, without any changes in the bone Ca resorption rate. The reduction in bone turnover revealed by the decrease of Vo+/Vo- was accompanied by less recovery velocity of calcemia in the aluminum treated group, being indirectly related to the parathyroid gland response to calcium depletion. In the model that we studied the decreased bone turnover could have been caused by deposits of aluminum in bone; however there could exist associated factors such as dysfunction in the secretion of PTH, or less affinity between its receptors at the bone level. PMID:9504191

  12. Polymer Coated CaAl-Layered Double Hydroxide Nanomaterials for Potential Calcium Supplement

    PubMed Central

    Kim, Tae-Hyun; Lee, Jeong-A; Choi, Soo-Jin; Oh, Jae-Min

    2014-01-01

    We have successfully prepared layered double hydroxide (LDH) nanomaterials containing calcium and aluminum ions in the framework (CaAl-LDH). The surface of CaAl-LDH was coated with enteric polymer, Eudragit®L 100 in order to protect nanomaterials from fast dissolution under gastric condition of pH 1.2. The X-ray diffraction patterns, Fourier transform infrared spectroscopy, scanning electron and transmission electron microscopy revealed that the pristine LDH was well prepared having hydrocalumite structure, and that the polymer effectively coated the surface of LDH without disturbing structure. From thermal analysis, it was determined that only a small amount (less than 1%) of polymer was coated on the LDH surface. Metal dissolution from LDH nanomaterials was significantly reduced upon Eudragit®L 100 coating at pH 1.2, 6.8 and 7.4, which simulates gastric, enteric and plasma conditions, respectively, and the dissolution effect was the most suppressed at pH 1.2. The LDH nanomaterials did not exhibit any significant cytotoxicity up to 1000 μg/mL and intracellular calcium concentration significantly increased in LDH-treated human intestinal cells. Pharmacokinetic study demonstrated absorption efficiency of Eudragit®L 100 coated LDH following oral administration to rats. Moreover, the LDH nanomaterials did not cause acute toxic effect in vivo. All the results suggest the great potential of CaAl-LDH nanomaterials as a calcium supplement. PMID:25490138

  13. Kinetics of pyrite oxidation in sodium hydroxide solutions

    NASA Astrophysics Data System (ADS)

    Ciminelli, V. S. T.; Osseo-Asare, K.

    1995-08-01

    The kinetics of pyrite oxidation in sodium hydroxide solution were investigated in a stirred reactor, under temperatures ranging from 50 °C to 85 °C, oxygen partial pressures of up to 1 atm, particle size fractions from -150 + 106 to -38 + 10µm (-100 + 150 mesh to -400 mesh + 10 µ), and pH values of up to 12.5. The surface reaction is represented by the rate equation:- dN/dt = Sbk″pO0.5 2[oH- 0.25/(1 + k‴ pO2 0.5) where N represents moles of pyrite, S is the surface area of the solid particles, k″ and k″ are constants, b is a stoichiometric factor, pO2 is the oxygen partial pressure, and [OH-] is the hydroxyl ion concentration. The corresponding fractional conversion ( X) vs time behavior follows the shrinking particle model for chemical reaction control: 1 - (1 - X)1/3 = k ct The rate increases with the reciprocal of particle size and has an activation energy of 55.6 kJ/mol (13.6 kcal/mol). The relationship between reaction rate and oxygen partial pressure resembles a Langmuir-type equation and thus suggests that the reaction involves adsorption or desorption of oxygen at the interface. The square-root rate law may be due to the adsorption of a dissociated oxygen molecule. The observed apparent reaction order with respect to the hydroxyl ion concentration is a result of a complex combination of processes involving the oxidation and nydrolysis of iron, oxidation and hydrolysis of sulfur, and the oxygen reduction.

  14. Histological response of human pulps capped with calcium hydroxide and a self-etch adhesive containing an antibacterial component

    PubMed Central

    Parthasarathy, Ambalavanan; Kamat, Sharad B.; Kamat, Mamta; Kidiyoor, Krishnamurthy Haridas

    2016-01-01

    Aim: To compare human pulp tissue response following direct pulp capping with calcium hydroxide and a self-etch adhesive containing antibacterial component. Materials and Methods: Sixty-six erupted sound premolars scheduled to be extracted for orthodontic reasons were selected from 17 human subjects. Pulp exposures were made. Direct pulp capping was then performed using calcium hydroxide and a self-etch adhesive containing antibacterial component in its primer. The teeth were then restored with composite resin. Two teeth were maintained intact as a control group. After 7 and 30 days, teeth were extracted and processed for light microscopic examination using a histological scoring system. The teeth were divided into four groups (N = 16) according to the pulp capping materials used and their days of extraction. The results were then statistically analyzed by Mann-Whitney U-test. Results: After the 7-day observation period, the inflammatory reaction to the self-etch adhesive containing antibacterial component group was significantly less severe than that in the calcium hydroxide group (P < 0.05). After the 30-day observation period, the inflammatory reaction was slight in both groups, but specimens with dentin bridge formation in the self-etch adhesive group were significantly less common than those in the calcium hydroxide group (P < 0.05). PMID:27217644

  15. [Treatment of Baume class IV pulp diseases with calcium hydroxide: a clinical experimental study in Dakar].

    PubMed

    Gaye, F; Mbaye, M; Diop-Thiaw, F; Ndiaye, D

    2001-09-01

    The calcium hydroxide used as intracanalar temporary medication in modern endodontics, is the aim of this clinical and radiographic appraisal of endodontic treatment during two sessions (HESS J. C. and all. 1990); on 22 mature permanent teeth with peri apical lesion. In this second Dakar serial study, the mediate disinfection during 6 weeks in average, was followed by a root canal filling for: 11 mono-radicular teeth by compactage of gutta percha, adjusted monocone for 11 pluri-radicular teeth; and so by definitive coronal restoration. The direct magistral preparations used in this study are not expensive, but simple and efficient; our endodontic processing (pre-treatment and treatment) end up at clinical silence and radiographic apical healing in 90.91% of cases after 9 months for 66.67% of root canal filling located at the safety apical limit. PMID:11813684

  16. [Clinical and laboratory rationale for galvanophoresis of hydroxide copper-calcium by root canals treatment].

    PubMed

    Rumiantsev, V A; Bordina, G E; Ol'khovskaia, A V; Opeshko, V V; Nekrasov, A V

    2015-01-01

    Double blind study presents clinical and laboratory estimation of root canal system (RC) cleaning by endodontic treatment of apical periodontitis by means of galvanophoresis of hydroxide copper-calcium (GP HCC). In 60 patients the amount and composition of RC fluid from incisors and canines by GP HCC were estimated within 2 weeks with three different galvano-pair and the efficiency of RC decontamination were compared by standard report irrigation and GP HCC. The intensity of electroosmotic allocation of RC liquid by GP HCC is gradually increased at 4-5 day, and then slowly reduced at 10-12 day. The RC liquid contained proteins and carbohydrates - typical rests of pulp and biofilm. GP HCC suppresses aerobic and anaerobic microflora in RC 65.5% more effectively than standard irrigation and may be seen as an alternative method of endodontic treatment of apical periodontitis. PMID:25909607

  17. Microstructure of amorphous aluminum hydroxide in belite-calcium sulfoaluminate cement

    SciTech Connect

    Song, Fei; Yu, Zhenglei; Yang, Fengling; Lu, Yinong Liu, Yunfei

    2015-05-15

    Belite-calcium sulfoaluminate (BCSA) cement is a promising low-CO{sub 2} alternative to ordinary Portland cement. Herein, aluminum hydroxide (AH{sub 3}), the main amorphous hydration product of BCSA cement, was investigated in detail. The microstructure of AH{sub 3} with various quantities of gypsum was investigated via scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The AH{sub 3} with various morphologies were observed and confirmed in the resulting pastes. Particular attention was paid to the fact that AH{sub 3} always contained a small amount of Ca according to the results of EDS analysis. The AH{sub 3} was then characterized via high resolution transmission electron microscopy (HRTEM). The results of HRTEM indicated that Ca arose from nanosized tricalcium aluminate hexahydrate which existed in the AH{sub 3}.

  18. Pulpectomy: immediate root canal filling with calcium hydroxide. Concept and procedures.

    PubMed

    Leonardo, M R; Leal, J M; Simões Filho, A P

    1980-05-01

    From the clinical aspect the endodontic treatment is divided into two groups: (1) teeth with pulp vitality (biopulpectomy) and (2) pulpless teeth (necropulpectomy). The authors point out the necessity of knowing the clinical pathologic conditions and the macroscopic aspect of the dental pulp before endodontic treatment. They describe the clinical procedures that must be performed in cases when the tooth presents pulp vitality (biopulpectomy), emphasizing (1) the necessity of a field of operation in an aseptic condition; (2) the necessity of a noninjuring instrumentation; (3) the use of cytophylactic substances and not cytotoxic substances; and (4) the use of a root canal--filling technique that respects the limits of the pulp stump, employing calcium hydroxide, a substance that maintains its vitality and induces and accelerates the apical closure by hard-tissue deposition. PMID:6929467

  19. A Comparative Analysis of Antimicrobial Property of Wine and Ozone with Calcium Hydroxide and Chlorhexidine

    PubMed Central

    Ebenezar, A. V. Rajesh; Anand, Nirupa; Mary, A.Vinita; Mony, Bejoy

    2015-01-01

    Background The antibacterial properties of wine and ozone have been established but their antibacterial efficacies against endodontic pathogens are yet to be ascertained. Aim The purpose of this study is to comparatively evaluate the antibacterial property of ozonated water, white wine (14%) and de-alcoholised white wine. Materials and Methods S.mutans and E.faecalis were subcultured and inoculated in a nutrient broth for 24 hours. The following groups were formulated: Group 1A:2% Chlorhexidine (Control group); Group 1B:White wine; Group 1C:Dealcoholised white wine; Group 1D:Ozonated water; Group 2A: Ca(OH)2 + Chlorhexidine (Control group); Group 2B: White wine + Ca(OH)2; Group 2C:De-alcoholised White wine + Ca(OH)2 + chlorhexidine; Group 2D:White wine + Ca(OH)2 + chlorhexidine and group 2E: Dealcoholised white wine + Ca(OH)2 + chlorhexidine. The samples were allowed to diffuse into the culture medium for two hours, later the S. mutans were streaked on to the blood agar medium and the E. faecalis were streaked on to the Muller Hilton agar medium and incubated for 48 hours at 370C the zone of inhibition was measured after 48 hours. Results There was no growth of microorganisms seen with ozonated water. Chlorhexidine showed large zone of inhibition compared to the other groups. White wine has better antimicrobial property than de-alcoholised white wine, but when mixed with calcium hydroxide the dealcoholised white wine has better action against the microorganisms. Conclusion Ozonated water has the best antibacterial property and the antibacterial action of Calcium hydroxide is enhanced when it is mixed with de-alcoholised white wine. PMID:26266206

  20. Effect of calcium hydroxide on mechanical strength and biological properties of bioactive glass.

    PubMed

    Shah, Asma Tufail; Batool, Madeeha; Chaudhry, Aqif Anwar; Iqbal, Farasat; Javaid, Ayesha; Zahid, Saba; Ilyas, Kanwal; Bin Qasim, Saad; Khan, Ather Farooq; Khan, Abdul Samad; Ur Rehman, Ihtesham

    2016-08-01

    In this manuscript for the first time calcium hydroxide (Ca(OH)2) has been used for preparation of bioactive glass (BG-2) by co-precipitation method and compared with glass prepared using calcium nitrate tetrahydrate Ca(NO3)2·4H2O (BG-1), which is a conventional source of calcium. The new source positively affected physical, biological and mechanical properties of BG-2. The glasses were characterized by Fourier transform infrared (FTIR), X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA-DSC), BET surface area analysis and Knoop hardness. The results showed that BG-2 possessed relatively larger surface properties (100m(2)g(-1) surface area) as compared to BG-1 (78m(2)g(-1)), spherical morphology and crystalline phases (wollastonite and apatite) after sintering at lower than conventional temperature. These properties contribute critical role in both mechanical and biological properties of glasses. The Knoop hardness measurements revealed that BG-2 possessed much better hardness (0.43±0.06GPa at 680°C and 2.16±0.46GPa at 980°C) than BG-1 (0.24±0.01 at 680°C and 0.57±0.07GPA at 980°C) under same conditions. Alamar blue Assay and confocal microscopy revealed that BG-2 exhibited better attachment and proliferation of MG63 cells. Based on the improved biological properties of BG-2 as a consequent of novel calcium source selection, BG-2 is proposed as a bioactive ceramic for hard tissue repair and regeneration applications. PMID:27068802

  1. Kinetics and Mechanism of Calcium Hydroxide Conversion into Calcium Alkoxides: Implications in Heritage Conservation Using Nanolimes.

    PubMed

    Rodriguez-Navarro, Carlos; Vettori, Irene; Ruiz-Agudo, Encarnacion

    2016-05-24

    Nanolimes are alcohol dispersions of Ca(OH)2 nanoparticles used in the conservation of cultural heritage. Although it was believed that Ca(OH)2 particles were inert when dispersed in short-chain alcohols, it has been recently shown that they can undergo transformation into calcium alkoxides. Little is known, however, about the mechanism and kinetics of such a phase transformation as well as its effect on the performance of nanolimes. Here we show that Ca(OH)2 particles formed after lime slaking react with ethanol and isopropanol and partially transform (fractional conversion, α up to 0.08) into calcium ethoxide and isopropoxide, respectively. The transformation shows Arrhenius behavior, with apparent activation energy Ea of 29 ± 4 and 37 ± 6 kJ mol(-1) for Ca-ethoxide and Ca-isopropoxide conversion, respectively. High resolution transmission electron microscopy analyses of reactant and product phases show that the alkoxides replace the crystalline structure of Ca(OH)2 along specific [hkl] directions, preserving the external hexagonal (platelike) morphology of the parent phase. Textural and kinetic results reveal that this pseudomorphic replacement involves a 3D diffusion-controlled deceleratory advancement of the reaction front. The results are consistent with an interface-coupled dissolution-precipitation replacement mechanism. Analysis of the carbonation of Ca(OH)2 particles with different degree of conversion into Ca-ethoxide (α up to 0.08) and Ca-isopropoxide (α up to 0.04) exposed to air (20 °C, 80% relative humidity) reveals that Ca-alkoxides significantly reduce the rate of transformation into cementing CaCO3 and induce the formation of metastable vaterite, as opposed to stable calcite which forms in untransformed Ca(OH)2 samples. Similar effects are obtained when a commercial nanolime partially transformed into Ca-ethoxide is subjected to carbonation. Such effects may hamper/delay the strengthening or consolidation effects of nanolimes, thus having

  2. The study of modified calcium hydroxides with surfactants for acid gas removal during incineration.

    PubMed

    Tseng, H H; Wey, M Y; Lu, C Y

    2002-01-01

    The primary objective of the present work is to use additives to extend the sulfation reaction of the calcium hydroxide (Ca(OH)2) used to control SO2 emission from incineration processes. There are two reasons for adding surfactants (surface-active agent): (1) to provide an appropriate dispersion of the Ca(OH)2', thus preventing particle agglomeration due to humidity; (2) to alter the sulfation reaction environment by adsorbing heterogeneous materials on the surface of the Ca(OH)2 to extend the adsorption equilibrium. A dry scrubber integrated with a fabric filter was employed to study the effect of surfactants on the removal efficiency of acid gas in the flue gas with Ca(OH)2 as the sorbent. The operating parameters evaluated include: (1) the different surfactants (calcium lignosulfonate, sodium lignosulfonate, alkyl naphthalene sodium sulfonate and beta-naphthalene sodium sulfonate condensates) and (2) the composition of acid gas (i.e. sulfur dioxide (SO2), nitrogen oxide (NO) and hydrogen chloride (HCl)). The results show that modified Ca(OH)2 with surfactants could effectively decrease the emission of acid gas during incineration. Different additives had individual absorption efficiencies on different acid gases. On the whole, sodium lignosulfonate and beta-naphthalene sodium sulfonate condensates had better sorption capacity for SO2 and NO, but not for HCl. In addition, when SO2 coexisted with NO and HCl, the concentration of NO and HCl will result in decrease or increase of the removal efficiency of SO2. PMID:11924579

  3. Coronal Discoloration Induced by Calcium-Enriched Mixture, Mineral Trioxide Aggregate and Calcium Hydroxide: A Spectrophotometric Analysis

    PubMed Central

    Esmaeili, Behnaz; Alaghehmand, Homayoun; Kordafshari, Tavoos; Daryakenari, Ghazaleh; Ehsani, Maryam; Bijani, Ali

    2016-01-01

    Introduction: The aim of this study was to compare the discoloration potential of calcium-enriched mixture (CEM) cement, white mineral trioxide aggregate (WMTA) and calcium hydroxide (CH), after placement in pulp chamber. Methods and Materials: Access cavities were prepared in 40 intact maxillary central incisors. Then, a 2×2 mm box was prepared on the middle third of the inner surface on the buccal wall of the access cavity. The specimens were randomly assigned into four groups; the boxes in the control group were left empty, in groups 1 to 3, the boxes were filled with CH, WMTA and CEM cement, respectively. The access cavities and the apical openings were sealed using resin modified glass ionomer (RMGI). The color measurement was performed with a spectrophotometer at the following intervals: before (T0), immediately after placement of the filling material (T1), one week (T2), 1 month (T3), 3 months (T4) and 5 months (T5) after filling of the box and finally immediately after removing the material from the boxes (T6). Color change (ΔE) values were calculated using the sample Kolmogorov-Smirnov test to determine the normal distribution of data, followed by ANOVA, repeated measured ANOVA and post-hoc Tukey’s tests. Results: All materials led to clinically perceptible crown discoloration after 1 week. The highest ΔE value belonged to WMTA group. Discoloration induced by CEM cement was not significantly different from CH or the control group (P>0.05). Conclusion: CEM cement may be the material of choice in the esthetic region, specifically pertaining to its lower color changing potential compared to WMTA. PMID:26843873

  4. Aqueous and surface chemistry of calcium-metal hydroxides in high pH environments

    SciTech Connect

    Cocke, D.L.; Mollah, M.Y.A.; Hess, T.R.; Lin, T.C.

    1997-08-01

    There is considerable interest in the chemistry associated with hazardous waste treatment by cement. The hydration of Portland cement is retarded in presence of zinc, cadmium and lead ions. Mixed hydroxides of calcium, zinc, cadmium and lead have been recently identified in the high pH environments of hydrating cement. FTIR, XRD, SEM, and SPM have been used to characterize these systems. A chemical equilibrium model of the early hydration of a zinc-doped cement/water system, Na-K-Ca-ZnH-SO{sub 4}-OH-Zn(OH){sub 2}-Zn(OH){sub 3}-Zn(OH){sub 4}-H{sub 2}O, has been developed to better understand the mechanism of the surface formation of calcium hydroxyzincate (CHZ). The model is based on Pitzer`s semi-empirical method for calculation of ion-activity coefficients at high ionic strength. The Pitzer parameters for Na{sup +}-Zn{sup 2+}, Na{sup +}-Zn{sup 2+}-SO{sub 4}{sup 2{minus}} and K{sup +}-Zn(OH){sub 4}{sup 2{minus}} have been evaluated, and the results successfully predict the equilibria (solubilities) of Na{sub 2}SO{sub 4}-ZnSO{sub 4}-H{sub 2}O, NaOH-Zn(OH){sub 2}-H{sub 2}O and KOH-ZnO-H{sub 2}O systems. The chemical model clearly demonstrates that the formation of CHZ on the calcium-silica-hydrate (C-S-H) surface is critically controlled by the Ca{sup 2+} ion concentration as well as pH of the pore water system. The results of this study suggest that the growth of CHZ is preceded by surface complex formation. Sequential charge control and sequential structure development have been used to discuss the surface selectivity of these compounds and their control of cement hydration.

  5. An empirical model to estimate density of sodium hydroxide solution: An activator of geopolymer concretes

    NASA Astrophysics Data System (ADS)

    Rajamane, N. P.; Nataraja, M. C.; Jeyalakshmi, R.; Nithiyanantham, S.

    2016-02-01

    Geopolymer concrete is zero-Portland cement concrete containing alumino-silicate based inorganic polymer as binder. The polymer is obtained by chemical activation of alumina and silica bearing materials, blast furnace slag by highly alkaline solutions such as hydroxide and silicates of alkali metals. Sodium hydroxide solutions of different concentrations are commonly used in making GPC mixes. Often, it is seen that sodium hydroxide solution of very high concentration is diluted with water to obtain SHS of desired concentration. While doing so it was observed that the solute particles of NaOH in SHS tend to occupy lower volumes as the degree of dilution increases. This aspect is discussed in this paper. The observed phenomenon needs to be understood while formulating the GPC mixes since this influences considerably the relationship between concentration and density of SHS. This paper suggests an empirical formula to relate density of SHS directly to concentration expressed by w/w.

  6. Textural properties of synthetic nano-calcite produced by hydrothermal carbonation of calcium hydroxide

    NASA Astrophysics Data System (ADS)

    Montes-Hernandez, G.; Fernández-Martínez, A.; Charlet, L.; Tisserand, D.; Renard, F.

    2008-05-01

    The hydrothermal carbonation of calcium hydroxide (Ca(OH) 2) at high pressure of CO 2 (initial P=55 bar) and moderate to high temperature (30 and 90 °C) was used to synthesize fine particles of calcite. This method allows a high carbonation efficiency (about 95% of Ca(OH) 2-CaCO 3 conversion), a significant production rate (48 kg/m 3 h) and high purity of product (about 96%). However, the various initial physicochemical conditions have a strong influence on the crystal size and surface area of the synthesized calcite crystals. The present study is focused on the estimation of the textural properties of synthesized calcite (morphology, specific surface area, average particle size, particle size distribution and particle size evolution with reaction time), using Rietveld refinements of X-ray diffraction (XRD) spectra, Brunauer-Emmett-Teller (BET) measurements, and scanning electron microscope (SEM) and transmission electron microscope (TEM) observations. This study demonstrate that the pressure, the temperature and the dissolved quantity of CO 2 have a significant effect on the average particle size, specific surface area, initial rate of precipitation, and on the morphology of calcium carbonate crystals. In contrast, these PT x conditions used herein have an insignificant effect on the carbonation efficiency of Ca(OH) 2. Finally, the results presented here demonstrate that nano-calcite crystals with high specific surface area ( SBET=6-10 m 2/g) can be produced, with a high potential for industrial applications such as adsorbents and/or filler in papermaking industry.

  7. Electronic and optical properties of magnesium and calcium hydroxides: the role of covalency and many-body effects

    NASA Astrophysics Data System (ADS)

    Karazhanov, Smagul Zh; Pishtshev, Aleksandr; Klopov, M.

    2015-09-01

    Magnesium and calcium hydroxides X(OH)2 (X = Mg, Ca) are multifunctional materials that have many important applications in industry, technology, and research. In solid-state electronics, the emerging applications of these compounds are related to photovoltaic devices. In the present paper we review electronic properties of X(OH)2, band gaps, work function, and features of chemical bonding and discuss theoretically predicted exciton effects.

  8. Tissue Reaction to Different Types of Calcium Hydroxide Paste in Rat.

    PubMed

    Zarei, Mina; Javidi, Maryam; Gharechahi, Maryam; Kateb, Moaied; Zare, Reza; Kelagari, Ziba Shirkhani

    2016-01-01

    The purpose of this study was to compare the biocompatibility of two types of calcium hydroxide paste in subcutaneous tissue in rat. Twenty-two Wistar rats were divided into 4 experimental (n=5 each) and one control (n=2) group. A polyethylene tube filled with either Dentsply or Sure-Paste was implanted in each rat in the experimental groups, while an empty polyethylene tube was used in the control group. After 15 or 60 days, the animals were sacrificed and histopathological examination carried out. Tissue reaction was assessed by inflammatory cell infiltration using a 4-point scoring system, ranging from 0 to 3. Data were analyzed with the Kruskal-Wallis, Wilcoxon, and McNemar tests. Both types of paste induced an inflammatory response at each time point, although the intensity varied. A significant reduction in the number of inflammatory cells was observed at 60 days. Dentsply appeared to induce a more marked inflammatory response at both time points, although the difference was not significant. These results suggest that both types of paste are biocompatible with subcutaneous tissue in rat. PMID:27320294

  9. Dual nutraceutical nanohybrids of folic acid and calcium containing layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Hyun; Oh, Jae-Min

    2016-01-01

    Dual nutraceutical nanohybrids consisting of organic nutrient, folic acid (FA), and mineral nutrient, calcium, were prepared based on layered double hydroxide (LDH) structure. Among various hybridization methods such as coprecipitation, ion exchange, solid phase reaction and exfoliation-reassembly, it was found that exfoliation-reassembly was the most effective in terms of intercalation of FA moiety between Ca-containing LDH layers. X-ray diffraction patterns and infrared spectra indicated that FA molecules were well stabilized in the interlayer space of LDHs through electrostatic interaction. From the atomic force and scanning electron microscopic studies, particle thickness of LDH was determined to be varied with tens, a few and again tens of nanometers in pristine, exfoliated and reassembled state, respectively, while preserving particle diameter. The result confirmed layer-by-layer hybrid structure of FA and LDHs was obtained by exfoliation-reassembly. Solid UV-vis spectra showed 2-dimensional molecular arrangement of FA moiety in hybrid, exhibiting slight red shift in n→π* and π→π* transition. The chemical formulae of FA intercalated Ca-containing LDH were determined to Ca1.30Al(OH)4.6FA0.74·3.33H2O and Ca1.53Fe(OH)5.06FA2.24·9.94H2O by inductively coupled plasma-atomic emission spectroscopy, high performance liquid chromatography and thermogravimetry, showing high nutraceutical content of FA and Ca.

  10. Evaluation of formocresol, calcium hydroxide, ferric sulfate, and MTA primary molar pulpotomies

    PubMed Central

    Yildiz, Esma; Tosun, Gul

    2014-01-01

    Objective: The aim of this study is to evaluate four different pulpotomy medicaments in primary molars. Materials and Methods: A total of 147 primary molars with deep caries were treated with four different pulpotomy medicaments (FC: formocresol, FS: ferric sulfate, CH: calcium hydroxide, and MTA: mineral trioxide aggregate) in this study. The criteria for tooth selection for inclusion were no clinical and radiographic evidence of pulp pathology. During 30 months of follow-up at 6-month intervals, clinical and radiographic success and failures were recorded. The differences between the groups were statistically analyzed using the Chi-square test and Kaplan-Meier analysis. Results: At 30 months, clinical success rates were 100%, 95.2%, 96.4%, and 85% in the FC, FS, MTA, and CH groups, respectively. In radiographic analysis, the MTA group had the highest (96.4%), and the CH group had the lowest success rate (85%). There were no clinical and radiographic differences between materials (P > 0.05). Conclusions: Although there were no differences between materials, only in the CH group did three teeth require extraction due to further clinical symptoms of radiographic failures during the 30-month follow-up period. None of the failed teeth in the other groups required extraction during the 30-month follow-up period. PMID:24966776

  11. In Vitro Comparison of the Effectiveness of Chlorhexidine and Two Calcium Hydroxide Formulations on Enterococcus Faecalis

    PubMed Central

    Sharifian, Mohammad Reza; Shokouhinejad, Noushin; Aligholi, Marzieh; Emaneini, Mohammad; Katebi, Arash; Assadian, Hadi

    2008-01-01

    INTRODUCTION: The aim of this in vitro study was to compare the effectiveness of three intracanal medicaments in disinfecting the root canal and dentin of experimentally infected human teeth with Enterococcus faecalis (EF). MATERIALS AND METHODS: One hundred extracted human single-rooted teeth were used. After root canal preparation, teeth were mounted in epoxy resin. Following sterilization, the teeth were infected for 28 days with EF. Then root canals were filled with one of three different disinfectants: viscous 2% Chlorhexidine (CHX), calcium hydroxide paste (CH) or a mixture of CH and CHX (n=30 in each group). Antimicrobial assessments were performed at 1, 3 and 7 days (n=10 in each time period). Microbial samples were obtained from root canals before and after the experiment. Also dentin samples were examined. The data was analyzed using Two- Way ANOVA test. RESULTS: The findings showed that there was no difference between experimental groups at different time periods. The mixture of CH/CHX in 7 days was able to eliminate EF completely from root canal system. The most elimination of EF was from dentinal tubules. CONCLUSION: According to the results of this in vitro study, viscous 2% CHX, mixture of CH with distilled water and 2% CHX are all effective disinfectants. PMID:24146671

  12. Antimicrobial Activity of Calcium Hydroxide and Betamethasone on Enterococcus faecalis; An in vitro Assessment

    PubMed Central

    Tabrizizadeh, Mahdi; Rasti, Mojtaba; Ayatollahi, Fatemeh; Mossadegh, Mohammad Hossein; Zandi, Hengameh; Dehghan, Farzad; Mousavi, Zohreh

    2015-01-01

    Introduction: Calcium hydroxide (CH) is one of the most common intracanal medications. Corticosteroids (CS) are used in endodontics because of their anti-inflammatory activity. This study aimed to evaluate the antimicrobial effect of CH+betamethasone and CH+saline against Enterococcus faecalis (E. faecalis) using agar diffusion test and measuring the microbial zone of inhibition (ZOI). Methods and Materials: Four plates containing Mueller-Hinton broth and E. faecalis culture media, were prepared. In each plate, 5 holes (5×3 mm) were created and a creamy mixture of CH+betamethasone was inserted into the holes (10 holes for each material). Two holes with ampicillin disks and two empty holes were used as negative and positive controls, respectively. Plates were incubated for 24 h and then the diameter of microbial ZOI was measured. The pH of each mixture was measured by pH meter. Data were analyzed using the Mann-Whitney U test. Results: The mean diameter of ZOI for CH+betamethasone and CH+saline was 3.4 and 3 mm, respectively. The difference was not significant (P=0.143). The pH was 12.5 for CH+saline and 12.3 CH+betamethasone, respectively. Conclusion: The mixture of CH+betamethasone had good antimicrobial effects against E. faecalis. Further studies are needed to confirm the value of this mixture in clinical settings. PMID:26213541

  13. Nestin expressions of exposed pulp after direct pulp capping by calcium hydroxide and platelet rich plasma

    PubMed Central

    Puspita, Sartika; Utoro, Totok; Haniastuti, Tetiana

    2016-01-01

    Objective: The aim of this study was to evaluate nestin expression of pulp tissue following direct pulp capping with platelet-rich plasma (PRP). Materials and Methods: The thirty sound teeth from Sprague-Dawley rats were used and divided into two groups: Groups 1, teeth were capped with calcium hydroxide/Ca(OH)2 (n = 15) and Group 2 with PRP (n = 15). After 1st, 7th, and 21st days, respectively, 5 teeth each group (American Dental Association 41) were processed for light microscopic examination. Expressions of nestin were assessed by immunohistochemical techniques. Results: Nestin expression of Ca(OH)2 on the distance place of exposure at 1st and 7th days were 80% and at 21st day were 60%. Nestin expression of PRP on the distance place at 1st day was 80%, 7th 100%, and 21st day was 80%. At day 21 observation, Kruskal–Wallis test shows nestin expression was increased significantly in PRP groups (P < 0.05), but it was not increase significantly compare with Ca(OH)2. Conclusion: PRP had ability as a direct pulp capping material to induce nestin expression. PMID:27403050

  14. Biocompatibility of a calcium hydroxide-propolis experimental paste in rat subcutaneous tissue.

    PubMed

    Mori, Graziela Garrido; Rodrigues, Sindineia da Silva; Shibayama, Sheila Tieko; Pomini, Marcelo; do Amaral, Cristhiane Olivia Ferreira

    2014-01-01

    Intracanal medications are fundamental for disinfection of the root canal system and participate in periapical repair, so their biocompatibility is of utmost importance to avoid tissue damage. This study evaluated the biocompatibility of a experimental paste of calcium hydroxide and propolis in the subcutaneous tissue of rats. The study was conducted on 15 male Wistar rats. Two incisions were made on the dorsal region of each animal for introduction of 4 tubes: one tube was empty; one contained zinc oxide-eugenol cement, and the two other tubes were filled with experimental paste. After 7, 14 and 30 days, the animals were euthanized and the specimens were subjected to histotechnical preparation. The hematoxylin and eosin-stained histological sections were analyzed by light microscopy. Scores were established according to the inflammatory process and statistically compared by the Tukey test (α = 5%). The analysis of histological sections showed non-significant or mild inflammatory reaction in the connective tissue in contact with the empty tubes in all study periods while the contact of subcutaneous tissue with zinc oxide-eugenol elicited moderate or severe inflammation similarly without significant difference among the study periods. The connective tissue was moderately inflamed at 7 days when contacting the experimental paste, but the inflammatory process was non-significant or mild at 14 and 30 days. The experimental paste was biocompatible with the tissues after 14 days of subcutaneous implantation. PMID:25140713

  15. Accidental injury of the inferior alveolar nerve due to the extrusion of calcium hydroxide in endodontic treatment: a case report.

    PubMed

    Shin, Yooseok; Roh, Byoung-Duck; Kim, Yemi; Kim, Taehyeon; Kim, Hyungjun

    2016-02-01

    During clinical endodontic treatment, we often find radiopaque filling material beyond the root apex. Accidental extrusion of calcium hydroxide could cause the injury of inferior alveolar nerve, such as paresthesia or continuous inflammatory response. This case report presents the extrusion of calcium hydroxide and treatment procedures including surgical intervention. A 48 yr old female patient experienced Calcipex II extrusion in to the inferior alveolar canal on left mandibular area during endodontic treatment. After completion of endodontic treatment on left mandibular first molar, surgical intervention was planned under general anesthesia. After cortical bone osteotomy and debridement, neuroma resection and neurorrhaphy was performed, and prognosis was observed. But no improvement in sensory nerve was seen following surgical intervention after 20 mon. A clinician should be aware of extrusion of intracanal medicaments and the possibility of damage on inferior alveolar canal. Injectable type of calcium hydroxide should be applied with care for preventing nerve injury. The alternative delivery method such as lentulo spiral was suggested on the posterior mandibular molar. PMID:26877992

  16. Accidental injury of the inferior alveolar nerve due to the extrusion of calcium hydroxide in endodontic treatment: a case report

    PubMed Central

    2016-01-01

    During clinical endodontic treatment, we often find radiopaque filling material beyond the root apex. Accidental extrusion of calcium hydroxide could cause the injury of inferior alveolar nerve, such as paresthesia or continuous inflammatory response. This case report presents the extrusion of calcium hydroxide and treatment procedures including surgical intervention. A 48 yr old female patient experienced Calcipex II extrusion in to the inferior alveolar canal on left mandibular area during endodontic treatment. After completion of endodontic treatment on left mandibular first molar, surgical intervention was planned under general anesthesia. After cortical bone osteotomy and debridement, neuroma resection and neurorrhaphy was performed, and prognosis was observed. But no improvement in sensory nerve was seen following surgical intervention after 20 mon. A clinician should be aware of extrusion of intracanal medicaments and the possibility of damage on inferior alveolar canal. Injectable type of calcium hydroxide should be applied with care for preventing nerve injury. The alternative delivery method such as lentulo spiral was suggested on the posterior mandibular molar. PMID:26877992

  17. Evaluation of sealing ability, pH and flow rate of three calcium hydroxide-based sealers.

    PubMed

    Siqueira, F J; Fraga, R C; Garcia, P F

    1995-10-01

    Three endodontic sealers containing calcium hydroxide (Sealapex, Sealer 26 and Apexit) and a zinc oxide-eugenol cement (Grossman's sealer) were examined for sealing ability, release of hydroxyl ions and flow rate. Dye penetration test was used to assess the sealing ability of the endodontic sealers. The pH test was accomplished to evaluate the release of hydroxyl ions from sealers and the pH readings were done at intervals of 30 min, 60 min and 7 days. In the flow test the sealers were placed between two glass slabs and a weight of 500 g was placed on the top of the glass. The diameters of the formed discs were recorded. The results revealed no statistically significant difference between apical seal provided by the four sealers. All of the calcium hydroxide based sealers alkalinized the surrounding medium. Sealer 26 cement presented significantly superior flow rate when compared with the other cements. These findings indicated that endodontic sealers containing calcium hydroxide presented satisfactory physicochemical properties when compared with a zinc oxide-eugenol sealer commonly used in endodontics. PMID:8625936

  18. Apexification of an Immature Permanent Incisor with the Use of Calcium Hydroxide: 16-Year Follow-Up of a Case

    PubMed Central

    Silveira, Camila Maggi Maia; Sebrão, Cátia Cilene Nass; Vilanova, Larissa Soares Reis; Sánchez-Ayala, Alfonso

    2015-01-01

    Apexification is a process of forming a mineralized apical barrier and had been performed by using calcium hydroxide paste, due to its biological and healing performances in cases of existent trauma. This clinical report aims to report the results of a 16-year follow-up study of an apexification treatment applied to nonvital tooth 22 of a healthy 8-year-old male after a trauma. Clinical inspection of the tooth showed fractures of the incisal edge and mesial angle, absence of coronal mobility, and negative pulp vitality under cold testing. Radiographic analysis of the root revealed incomplete apex formation. The possibility of fracture into the root or luxation injury was rejected, and the diagnosis of pulp necrosis was verified. Apexification by calcium hydroxide and subsequent endodontic treatment were planned. Initial formation of the mineralized apical barrier was observed after 3 months, and the barrier was considered to be completed after 8 months. Clinical, radiographic, and CBCT examinations after 16 years verified the success of the treatment, although the choice of calcium hydroxide for apexification treatment is discussed. PMID:26171256

  19. Layered double hydroxide stability. 2. Formation of Cr(III)-containing layered double hydroxides directly from solution

    NASA Technical Reports Server (NTRS)

    Boclair, J. W.; Braterman, P. S.; Jiang, J.; Lou, S.; Yarberry, F.

    1999-01-01

    Solutions containing divalent metal [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+] chlorides and CrCl3 6H2O were titrated with NaOH to yield, for M(II) = Zn, Co, and Ni, hydrotalcite-like layered double hydroxides (LDHs), [[M(II)]1-z[Cr(III)]z(OH)2][Cl]z yH2O, in a single step, without intermediate formation of chromium hydroxide. Analysis of the resultant titration curves yields solubility constants for these compounds. These are in the order Zn < Ni approximately Co, with a clear preference for formation of the phase with z = 1/3. With Mg2+ as chloride, titration gives a mixture of Cr(OH)3 and Mg(OH)2, but the metal sulfates give Mg2Cr(OH)6 1/2(SO4) by a two-step process. Titrimetric and spectroscopic evidence suggests short-range cation order in the one-step LDH systems.

  20. Aluminum hydroxide nucleation kinetics and mechanism during the electrodialysis decomposition of aluminate solutions

    NASA Astrophysics Data System (ADS)

    Lainer, Yu. A.; Gorichev, I. G.; Todorov, S. A.

    2008-08-01

    The kinetic laws of the electrodialysis decomposition of strong aluminate solutions are considered. Mathematical simulation is performed using the equations of the heterogeneous kinetics of aluminum hydroxide precipitation for the electrodialysis of aluminate solutions, and this simulation shows that the nature of the limiting stage is related to the instantaneous nucleation during the three-dimensional coalescence of particles. The electrodialysis precipitate is analyzed, and the possible commercial application of the decomposition of strong aluminate solutions by electrodialysis is considered.

  1. Device to generate high purity hydroxide solution in-line for ion chromatography.

    PubMed

    Masunaga, Hiroto; Higo, Yuji; Ishii, Mizuo; Maruyama, Noboru; Yamazaki, Shigeo

    2016-05-01

    Herein, we report a new device that generates a high-purity hydroxide solution in line. The device's container has three compartments that are isolated from each other by two cation exchange (CE) membranes. In each end of the container, an electrode is installed. The three compartments are filled with ion exchange resins. A bipolar boundary is a composite boundary comprising anion- and cation-exchangers. This device has two bipolar boundaries, which are used to separate the location of hydroxide solution generation from the location where water is electrolyzed. Therefore, it can produce high-purity hydroxide solutions that are free from gases and anionic impurities. The hydroxide solution is generated on the basis of an electrokinetic phenomenon at the surfaces of ion-exchange resins and membranes in an electric field; NaOH concentration can be controlled at rates from 0.01 to 100mM per 1mL/min by adjusting the electrical current (0-200mA) applied to the device. As the generated solution is used as an eluent for a suppressed anion chromatography, the electrical conductivity of the effluent from the suppressor is as low as that of ultra-pure water. Thus, the noise of the base-line electrical conductivity is improved, and so the detection limit of anions on the sub-ng/mL order can be achieved. PMID:27063368

  2. Vibrational dynamics of aqueous hydroxide solutions probed using broadband 2DIR spectroscopy

    SciTech Connect

    Mandal, Aritra; Tokmakoff, Andrei

    2015-11-21

    We employed ultrafast transient absorption and broadband 2DIR spectroscopy to study the vibrational dynamics of aqueous hydroxide solutions by exciting the O–H stretch vibrations of the strongly hydrogen-bonded hydroxide solvation shell water and probing the continuum absorption of the solvated ion between 1500 and 3800 cm{sup −1}. We observe rapid vibrational relaxation processes on 150–250 fs time scales across the entire probed spectral region as well as slower vibrational dynamics on 1–2 ps time scales. Furthermore, the O–H stretch excitation loses its frequency memory in 180 fs, and vibrational energy exchange between bulk-like water vibrations and hydroxide-associated water vibrations occurs in ∼200 fs. The fast dynamics in this system originate in strong nonlinear coupling between intra- and intermolecular vibrations and are explained in terms of non-adiabatic vibrational relaxation. These measurements indicate that the vibrational dynamics of the aqueous hydroxide complex are faster than the time scales reported for long-range transport of protons in aqueous hydroxide solutions.

  3. Vibrational dynamics of aqueous hydroxide solutions probed using broadband 2DIR spectroscopy.

    PubMed

    Mandal, Aritra; Tokmakoff, Andrei

    2015-11-21

    We employed ultrafast transient absorption and broadband 2DIR spectroscopy to study the vibrational dynamics of aqueous hydroxide solutions by exciting the O-H stretch vibrations of the strongly hydrogen-bonded hydroxide solvation shell water and probing the continuum absorption of the solvated ion between 1500 and 3800 cm(-1). We observe rapid vibrational relaxation processes on 150-250 fs time scales across the entire probed spectral region as well as slower vibrational dynamics on 1-2 ps time scales. Furthermore, the O-H stretch excitation loses its frequency memory in 180 fs, and vibrational energy exchange between bulk-like water vibrations and hydroxide-associated water vibrations occurs in ∼200 fs. The fast dynamics in this system originate in strong nonlinear coupling between intra- and intermolecular vibrations and are explained in terms of non-adiabatic vibrational relaxation. These measurements indicate that the vibrational dynamics of the aqueous hydroxide complex are faster than the time scales reported for long-range transport of protons in aqueous hydroxide solutions. PMID:26590536

  4. Vibrational dynamics of aqueous hydroxide solutions probed using broadband 2DIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Mandal, Aritra; Tokmakoff, Andrei

    2015-11-01

    We employed ultrafast transient absorption and broadband 2DIR spectroscopy to study the vibrational dynamics of aqueous hydroxide solutions by exciting the O-H stretch vibrations of the strongly hydrogen-bonded hydroxide solvation shell water and probing the continuum absorption of the solvated ion between 1500 and 3800 cm-1. We observe rapid vibrational relaxation processes on 150-250 fs time scales across the entire probed spectral region as well as slower vibrational dynamics on 1-2 ps time scales. Furthermore, the O-H stretch excitation loses its frequency memory in 180 fs, and vibrational energy exchange between bulk-like water vibrations and hydroxide-associated water vibrations occurs in ˜200 fs. The fast dynamics in this system originate in strong nonlinear coupling between intra- and intermolecular vibrations and are explained in terms of non-adiabatic vibrational relaxation. These measurements indicate that the vibrational dynamics of the aqueous hydroxide complex are faster than the time scales reported for long-range transport of protons in aqueous hydroxide solutions.

  5. Intra-canal calcium hydroxide removal by two rotary systems: A comparative study

    PubMed Central

    Dadresanfar, Bahare; Abbas, Fateme Mashhadi; Bashbaghi, Hamide; Miri, Shima Sadat; Ghorbani, Farshid

    2015-01-01

    Aim: The presence of calcium hydroxide (Ca(OH)2) in the root canal interferes with the apical root canal sealing and may result in periapical lesions in the long run. The present study was aimed to compare the efficacy of two rotary systems of Race and Mtwo in the removal of Ca (OH)2 aqueous-based from distobuccal canals of human maxillary molars. Materials and Methods: A total of 44 distobuccal root canals of human maxillary molars were randomly distributed into two groups of 20 canals each and two control groups. Specimens in each group were instrumented with similar master apical rotary (MAR) and flexible files according to the manufacture's guidelines. The Ca (OH)2 paste was placed in canals using # 20 lentulo and radiographs were taken from the two dimensions. The roots were incubated for 1 week at 37°C and 100% humidity and Ca (OH)2 was removed from canals by MAR, afterward. Then, the roots were longitudinally split in halves by diamond disk and chisel without entering the root canals. Photos were taken from the canals’ walls by a stereomicroscope with × 10 magnification. Next, according to a defined scoring system, photos were scored by four endodontists, so that scores 1 and 2 (nonvisible remnants or scattered remnants of Ca(OH)2) were considered as acceptable and scores 3 and 4 (distinct mass or densely-packed mass of Ca(OH)2) were regarded as nonacceptable. Results: The obtained findings indicated that in coronal, middle, and apical portions of the root canal, 45, 60, and 65% of Mtwo specimens and 40, 50, and 55% of specimens prepared by the Race system acquired an acceptable score (1 and 2), respectively. Moreover, the results showed no significant difference between the two groups (P > 0.05). Conclusions: Both Mtwo and Race rotary systems with acceptable removal efficiency (score 1 and 2) were similarly able to remove Ca(OH)2 PMID:26069416

  6. A novel approach for stabilizing fresh urine by calcium hydroxide addition.

    PubMed

    Randall, Dyllon G; Krähenbühl, Manuel; Köpping, Isabell; Larsen, Tove A; Udert, Kai M

    2016-05-15

    In this study, we investigated the prevention of enzymatic urea hydrolysis in fresh urine by increasing the pH with calcium hydroxide (Ca(OH)2) powder. The amount of Ca(OH)2 dissolving in fresh urine depends significantly on the composition of the urine. The different urine compositions used in our simulations showed that between 4.3 and 5.8 g Ca(OH)2 dissolved in 1 L of urine at 25 °C. At this temperature, the pH at saturation is 12.5 and is far above the pH of 11, which we identified as the upper limit for enzymatic urea hydrolysis. However, temperature has a strong effect on the saturation pH, with higher values being achieved at lower temperatures. Based on our results, we recommend a dosage of 10 g Ca(OH)2 L(-1) of fresh urine to ensure solid Ca(OH)2 always remains in the urine reactor which ensures sufficiently high pH values. Besides providing sufficient Ca(OH)2, the temperature has to be kept in a certain range to prevent chemical urea hydrolysis. At temperatures below 14 °C, the saturation pH is higher than 13, which favors chemical urea hydrolysis. We chose a precautionary upper temperature of 40 °C because the rate of chemical urea hydrolysis increases at higher temperatures but this should be confirmed with kinetic studies. By considering the boundaries for pH and temperature developed in this study, urine can be stabilized effectively with Ca(OH)2 thereby simplifying later treatment processes or making direct use easier. PMID:27055084

  7. Mineral Trioxide Aggregate vs. Calcium Hydroxide in Primary Molar Pulpotomy: A Systematic Review

    PubMed Central

    Shirvani, Armin; Hassanizadeh, Raheleh; Asgary, Saeed

    2014-01-01

    Introduction: The aim of this quantitative systematic review/meta-analysis was to compare the treatment outcomes of mineral trioxide aggregate (MTA) and calcium hydroxide (CH) in pulpotomy of human primary molars. The focused PICO question was “in case of pulp exposure in vital primary molars, how does MTA pulpotomy compare to CH in terms of clinical/radiographic success?” Methods and Materials: We retrieved published randomized clinical trials (RCTs) of at least 6-month duration; our search included articles published up to March 2013 in five following databases: PubMed (Medline), Cochrane database of systematic reviews, Science Citation Index, EMBASE, and Google Scholar. Mantel Haenszel and Inverse Variance-weighted methods were applied by STATA; the relative risk (RR) was calculated with 95% confidence intervals (CI). Results: A total of 282 English articles were collected. Two authors independently screened the articles and five RCTs were selected; data extraction and quality assessment were then carried out. Four RCTs were appropriate for meta-analysis according to their follow-up times by Mantel Haenszel method. Statistically significant difference was found between success rate of MTA compared to CH, with RR=0.08 (95% CI, 0.02-0.39), RR=0.19 (95% CI, 0.08-0.46), and RR=0.38 (95% CI, 0.21-0.68) for 6-, 12-, and 24-month follow-ups, respectively. A significant difference was also observed for all included RCTs after analyses using the Inverse Variance-weighted method (RR=0.44; 95% CI, 0.27-0.72). Conclusions: Systematic review/meta-analysis of included RCTs revealed that for pulpotomy of vital primary molars, MTA has better treatment outcomes compared to CH. PMID:24688575

  8. Effect of smear layer removal on the diffusion of calcium hydroxide through radicular dentin.

    PubMed

    Foster, K H; Kulild, J C; Weller, R N

    1993-03-01

    Forty single-rooted teeth were sectioned transversely through the cementoenamel junction and instrumented to a size #50 K-Flex file at the working length by saline irrigation. Each root was placed in a dilution vial containing 10 ml of normal saline, and the pH and Ca2+ levels were recorded after 24 h. The roots in group 1 then received a final irrigation with 20 ml of normal saline. Group 2 received a final irrigation with 10 ml of 17% ethylenediaminetetraacetic acid followed by 10 ml of 5.25% NaOCl to remove the smear layer. Group 3 was irrigated in the same manner as group 2, but calcium hydroxide (CH) was placed into the root canal. Group 4 was irrigated with 20 ml of NaOCl, and CH was placed into the root canal. The pH and Ca2+ levels were recorded at 1, 3, 5, and 7 days. After 7 days a 3- x 3- x 1-mm external defect was created in the coronal one third of the root surface. The pH and Ca2+ levels were subsequently recorded at 1, 3, and 7 days. Groups 3 and 4 demonstrated significantly higher H+ and Ca2+ levels than did groups 1 and 2 three days after CH placement and at all subsequent intervals. Group 3 demonstrated significantly higher H+ and Ca2+ readings at some but not all intervals. The results demonstrated that CH diffuses from the root canal to the exterior surface of the root and that the removal of the smear layer may facilitate this diffusion. PMID:8509752

  9. A novel approach for stabilizing fresh urine by calcium hydroxide addition

    PubMed Central

    Randall, Dyllon G.; Krähenbühl, Manuel; Köpping, Isabell; Larsen, Tove A.; Udert, Kai M.

    2016-01-01

    In this study, we investigated the prevention of enzymatic urea hydrolysis in fresh urine by increasing the pH with calcium hydroxide (Ca(OH)2) powder. The amount of Ca(OH)2 dissolving in fresh urine depends significantly on the composition of the urine. The different urine compositions used in our simulations showed that between 4.3 and 5.8 g Ca(OH)2 dissolved in 1 L of urine at 25 °C. At this temperature, the pH at saturation is 12.5 and is far above the pH of 11, which we identified as the upper limit for enzymatic urea hydrolysis. However, temperature has a strong effect on the saturation pH, with higher values being achieved at lower temperatures. Based on our results, we recommend a dosage of 10 g Ca(OH)2 L−1 of fresh urine to ensure solid Ca(OH)2 always remains in the urine reactor which ensures sufficiently high pH values. Besides providing sufficient Ca(OH)2, the temperature has to be kept in a certain range to prevent chemical urea hydrolysis. At temperatures below 14 °C, the saturation pH is higher than 13, which favors chemical urea hydrolysis. We chose a precautionary upper temperature of 40 °C because the rate of chemical urea hydrolysis increases at higher temperatures but this should be confirmed with kinetic studies. By considering the boundaries for pH and temperature developed in this study, urine can be stabilized effectively with Ca(OH)2 thereby simplifying later treatment processes or making direct use easier. PMID:27055084

  10. Sulfur removal from Gediz lignite using aqueous sodium hydroxide solutions under mild oxidative conditions

    SciTech Connect

    Yaman, S.; Kuecuekbayrak, S.

    1999-11-01

    Sulfur removal from a high-sulfur Turkish lignite (Gediz) using aqueous sodium hydroxide solutions having dissolved oxygen was investigated under mild oxidative conditions. Effects of the parameters such as sodium hydroxide/lignite weight ratio, temperature, and partial pressure of oxygen were investigated within the ranges of 0.05--0.8, 423--498 K, and 1--2 MPa, respectively. Optimum values of these parameters were determined regarding sulfur removal and coal recovery. Influences of dry oxidation of the lignite sample as a pretreatment at 573 K and subsequent washing of some treated lignite samples with 1 N HCl were investigated.

  11. Kinetics of leaching of the aluminum hydroxide in bauxites by alkaline solutions at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Burtsev, A. V.; Lainer, Yu. A.; Gorichev, I. G.; Kipriyanov, N. A.; Izotov, A. D.

    2011-11-01

    The kinetics of leaching of the aluminum hydroxide from the gibbsite bauxites of Guinea (Kindia deposit) is studied under atmospheric conditions. The activation energy of the process is found to be 34.75 kJ/mol, which indicates that the process proceeds in a kinetic mode. The leaching of the aluminum hydroxide from bauxite in an alkaline solution is simulated using acid-base equilibria (ion exchange) and the electrochemical theory of the structure of a double electrical layer (Gram-Parsons theory).

  12. Anodic dissolution and protection of aluminum alloy 7075 in hydroxide solutions

    SciTech Connect

    McCafferty, E.; Trzaskoma-Paulette, P.

    1997-03-01

    Dissolution of Al 7075 (UNS A97075) in sodium hydroxide (NaOH) solutions results in formation of a black, loosely adherent film of corrosion products that provides partial protection in the aqueous environment. Optical and scanning microscopy showed the reaction product film is a bilayer, with a thin, adherent inner layer and a thicker, more fragile outer layer. The reaction mechanism involves the dissolution of aluminum followed by formation of a precipitated film. Corrosion protection at moderate hydroxide concentrations is provided by the use of a partially fluorinated amino-surfactant or a silicon nitride (Si{sub 3}N{sub 4}) coating prepared by ion beam-assisted deposition.

  13. Elimination of intracanal infection in dogs' teeth with induced periapical lesions after rotary instrumentation: influence of different calcium hydroxide pastes.

    PubMed

    Soares, Janir Alves; Leonardo, Mário Roberto; da Silva, Léa Assed Bezerra; Tanomaru Filho, Mário; Ito, Izabel Yoko

    2006-06-01

    The aim of this study was to evaluate the antiseptic efficacy of rotary instrumentation associated with calcium hydroxide-based pastes prepared with different vehicles and antiseptics. Chronic periapical lesions were experimentally induced in 72 premolar root canals of four dogs. Under controlled asepsis, after initial microbiological sampling (A1), the root canals were instrumented using the ProFile system in conjunction with 5.25% sodium hypochlorite and the intracanal medication was placed. Four experimental groups were formed according to the pastes used: group 1- Calen (n=18), group 2- Calen+CPMC (n=20), group 3- Ca(OH)(2) p.a.+ anaesthetic solution (n=16) and group 4- Ca(OH)(2) p.a.+ 2% chlorhexidine digluconate (n=18). After 21 days, the pastes were removed; the canals were emptied and 96 hours later a second microbiological sample was obtained (A2). The incidence of positive microbiological cultures and the number of cfus in stages A1 and A2 were compared statistically by the Wilcoxon test while the influence of the different treatments in intracanal infection was evaluated by Kruskal-Wallis test at 5% significance level (p<0.05). Large numbers of strict and facultative anaerobes, and viridans group streptococci were found in 100% of root canals of A1 samples. Among A2 samples, all treatments showed significant reduction of cfus and positive cultures (p<0.05), but only groups 3 and 4 showed 100% of root canals free of microorganisms. Rotary instrumentation plus NaOCl 5.25% associated with intracanal medication produced a drastic reduction or elimination of intracanal microbiota, whose performance was not influenced by the nature of the vehicle or the antiseptic added to the Ca(OH)(2) p.a. PMID:19089068

  14. ELIMINATION OF INTRACANAL INFECTION IN DOGS' TEETH WITH INDUCED PERIAPICAL LESIONS AFTER ROTARY INSTRUMENTATION: INFLUENCE OF DIFFERENT CALCIUM HYDROXIDE PASTES

    PubMed Central

    Soares, Janir Alves; Leonardo, Mário Roberto; da Silva, Léa Assed Bezerra; Tanomaru, Mário; Ito, Izabel Yoko

    2006-01-01

    The aim of this study was to evaluate the antiseptic efficacy of rotary instrumentation associated with calcium hydroxide-based pastes prepared with different vehicles and antiseptics. Chronic periapical lesions were experimentally induced in 72 premolar root canals of four dogs. Under controlled asepsis, after initial microbiological sampling (A1), the root canals were instrumented using the ProFile system in conjunction with 5.25% sodium hypochlorite and the intracanal medication was placed. Four experimental groups were formed according to the pastes used: group 1- Calen (n=18), group 2- Calen+CPMC (n=20), group 3- Ca(OH)2 p.a.+ anaesthetic solution (n=16) and group 4- Ca(OH)2 p.a.+ 2% chlorhexidine digluconate (n=18). After 21 days, the pastes were removed; the canals were emptied and 96 hours later a second microbiological sample was obtained (A2). The incidence of positive microbiological cultures and the number of cfus in stages A1 and A2 were compared statistically by the Wilcoxon test while the influence of the different treatments in intracanal infection was evaluated by Kruskal-Wallis test at 5% significance level (p<0.05). Large numbers of strict and facultative anaerobes, and viridans group streptococci were found in 100% of root canals of A1 samples. Among A2 samples, all treatments showed significant reduction of cfus and positive cultures (p<0.05), but only groups 3 and 4 showed 100% of root canals free of microorganisms. Rotary instrumentation plus NaOCl 5.25% associated with intracanal medication produced a drastic reduction or elimination of intracanal microbiota, whose performance was not influenced by the nature of the vehicle or the antiseptic added to the Ca(OH)2 p.a. PMID:19089068

  15. Effect of Calcium Hydroxide, Chlorhexidine Digluconate and Camphorated Monochlorophenol on the Sealing Ability of Biodentine Apical Plug

    PubMed Central

    Srivastava, Harshit; Prasad, Ashwini B; Raisingani, Deepak; Soni, Dileep

    2016-01-01

    Introduction Teeth with immature apex are managed by establishing an apical plug using various materials and techniques. However, the use of previously placed intracanal medicament may affect the sealing ability of permanent filling material used as an apical plug. Aim To evaluate the effect of removal of previously placed Calcium Hydroxide, Chlorhexidine Digluconate and Camphorated Monochlorophenol as an intracanal medicament on the sealing ability of the Biodentine as an apical plug. Materials and Methods A total of 72 recently extracted human permanent teeth with single root were selected and stored in saline at room temperature. The crown portion of each tooth was removed at the level of cemento enamel junction; 14mm root length was taken as standard length. All the roots were submerged in 20% sulphuric acid up to 3 mm from the apex, for four days for root resorption. One sample was cut longitudinally to look for root resorption under stereo microscope. The canal preparation was done; the roots were kept in moist gauze after instrumentation. A total of 71 roots were randomly divided into three groups. GROUP 1:Calcium hydroxide paste, GROUP 2: Chlorhexidine digluconate, GROUP 3: Camphorated Monochlorophenol (CMCP). The medicaments were removed with stainless steel hand files and 0.5% sodium hypochlorite irrigation. After removal of medicament Biodentine was placed in apical third of resorbed roots and the remaining portion of the canals was filled with gutta-percha. All the 71 roots were analysed with fluid filtration method for evaluating microleakage. Results Comparing all the three groups statistically there was no significant difference. The mean values were found more for group 1 followed by group 2 & 3. Conclusion All the groups showed microleakage. Calcium hydroxide showed the maximum microleakage followed by Chlorhexidine digluconate and least with CMCP. PMID:27504409

  16. Effect of calcium hydroxide on the bond strength of two bioactive cements and SEM evaluation of failure patterns.

    PubMed

    Centenaro, Carolina Fabiana; Santini, Manuela Favarin; da Rosa, Ricardo Abreu; Nascimento, Angela Longo do; Kuga, Milton Carlos; Pereira, Jefferson Ricardo; Só, Marcus Vinícius Reis

    2016-05-01

    The aim of this study was to assess the effect of calcium hydroxide on bond strength of two bioactive cements. One-mm thick longitudinal slabs of root dentin were obtained from freshly extracted human monorradicular teeth (n = 60). Simulated root perforations (1 mm in diameter) were prepared in radicular dentin. Thereafter, the specimens were randomly divided into two groups (n = 30), according to the repair material: MTA (n = 30) and Biodentine (BD) (n = 30). Next, the specimens in each group were further randomly divided into 4 equal subgroups (n = 15) according to the prior use of Ca(OH)2: MTA/Ca(OH)2 and BD/Ca(OH)2 groups: perforations were filled with calcium hydroxide [Ca(OH)2] and after 7 days, it was removed, and MTA and BD groups: calcium hydroxide dressing were not used. Push-out test was performed at a crosshead speed of 1 mm/min. Bond strength values were compared statistically using Kruskal-Wallis test and Dunn's post-test at a significance level of 5%. The failure analysis was performed using a stereoscopic and classified as adhesive, cohesive and mixed. The push-out bond strength of MTA and BD was not affected by the prior use of Ca(OH)2 (p > 0.05). BD yielded higher push-out bond strength values compared with those of MTA, regardless of the use of Ca(OH)2 (p < 0.05). Mixed failures were predominant in all groups. Ca(OH)2 placement for perforations sealing does not alter the bond strength of MTA and BD to the root dentin. BD presented higher bond strength values than MTA. SCANNING 38:240-244, 2016. © 2015 Wiley Periodicals, Inc. PMID:26331376

  17. The effect of nonsetting calcium hydroxide on root fracture and mechanical properties of radicular dentine: a systematic review.

    PubMed

    Yassen, G H; Platt, J A

    2013-02-01

    The aim of this review was to identify and analyse all studies related to the effect of nonsetting calcium hydroxide [Ca(OH)(2)] on root fracture and various mechanical properties of radicular dentine. A PubMed search was conducted using the keywords 'calcium hydroxide' and 'dentistry' combined with MeSH terms 'tooth fractures' or 'mechanical phenomena' or 'compressive strength'. The search was expanded by including Embase and Web of Science databases, using the keywords 'calcium hydroxide' and 'root' and 'fracture'. The search was supplemented by checking the reference lists from each selected article. Each study had to meet the following criteria to be selected for review: (i) Inclusion of at least one experimental group with root or radicular dentine either filled with or exposed to nonsetting Ca(OH)(2); (ii) inclusion of at least one appropriate control group; and (iii) a minimum of five samples per experimental group. Only articles written in English were included. Of the 16 studies selected initially, 12 in vitro studies fulfilled the selection criteria for inclusion in the final review. No clinical studies that directly supported the correlation between Ca(OH)(2) intracanal dressing and root fracture were found in the literature. However, the majority of in vitro studies showed reduction in the mechanical properties of radicular dentine after exposure to Ca(OH)(2) for 5 weeks or longer. Conversely, the data were inconclusive regarding whether Ca(OH)(2) exposure for 1 month or less had a negative effect on the mechanical properties of radicular dentine. PMID:22970899

  18. Antioxidant and cytoprotective activities of Piper betle, Areca catechu, Uncaria gambir and betel quid with and without calcium hydroxide

    PubMed Central

    2013-01-01

    Background Betel quid chewing is a popular habit in Southeast Asia. It is believed that chewing betel quid could reduce stress, strengthen teeth and maintain oral hygiene. The aim of this study was to investigate the antioxidant and cytoprotective activities of each of the ingredients of betel quid and compared with betel quid itself (with and without calcium hydroxide). The correlation of their cytoprotective and antioxidant activities with phenolic content was also determined. Methods Five samples (betel leaf, areca nut, gambir, betel quid and betel quid containing calcium hydroxide) were extracted in deionized distilled water for 12 hours at 37°C. Antioxidant activities were evaluated for radical scavenging activity using DPPH assay, ferric reducing activity using FRAP assay and lipid peroxidation inhibition activity using FTC assay. Total phenolic content (TPC) was determined using Folin-Ciocalteu procedure. Phenolic composition was analyzed using LC-MS/MS. Cytoprotective activity towards human gingival fibroblast cells was examined using MTT assay. Results Among the ingredients of betel quid, gambir demonstrated the highest antioxidant (DPPH - IC50 = 6.4 ± 0.8 μg/mL, FRAP - 5717.8 ± 537.6 μmol Fe(II)/mg), total phenolic content (TPC - 1142.5 ± 106.8 μg TAE/mg) and cytoprotective (100.1 ± 4.6%) activities. Betel quid when compared with betel quid containing calcium hydroxide has higher antioxidant (DPPH - IC50 =59.4 ± 4.4 μg/mL, FRAP - 1022.2 ± 235.7 μmol Fe(II)/mg), total phenolic content (TPC - 140.0 ± 22.3 μg TAE/mg), and cytoprotective (113.5 ± 15.9%) activities. However, all of the five samples showed good lipid peroxidation inhibition compared to vitamin E. LC-MS/MS analysis revealed the presence of quinic acid as the major compound of gambir and betel quid. A positive correlation was observed between TPC and radical scavenging (r = 0.972), reducing power (r = 0.981) and cytoprotective

  19. Detection of copper ions from aqueous solutions using layered double hydroxides thin films deposited by PLD

    NASA Astrophysics Data System (ADS)

    Vlad, A.; Birjega, R.; Matei, A.; Luculescu, C.; Nedelcea, A.; Dinescu, M.; Zavoianu, R.; Pavel, O. D.

    2015-10-01

    Layered double hydroxides (LDHs) thin films with Mg-Al were deposited using pulsed laser deposition (PLD) technique. We studied the ability of our films to detect copper ions in aqueous solutions. Copper is known to be a common pollutant in water, originating from urban and industrial waste. Clay minerals, including layered double hydroxides (LDHs), can reduce the toxicity of such wastes by adsorbing copper. We report on the uptake of copper ions from aqueous solution on LDH thin films obtained via PLD. The obtained thin films were characterized using X-ray Diffraction, Atomic Force Microscopy, and Scanning Electron Microscopy with Energy Dispersive X-ray analysis. The results in this study indicate that LDHs thin films obtained by PLD have potential as an efficient adsorbent for removing copper from aqueous solution.

  20. Structure and properties of alizarin complex formed with alkali metal hydroxides in methanol solution.

    PubMed

    Jeliński, Tomasz; Cysewski, Piotr

    2016-06-01

    Quantum chemical computations were used for prediction of the structure and color of alizarin complex with alkali metal hydroxides in methanolic solutions. The color prediction relying on the single Gaussian-like band once again proved the usefulness of the PBE0 density functional due to the observed smallest color difference between computed and experimentally derived values. It was found that the alkali metal hydroxide molecules can bind to the two oxygen atoms of both hydroxyl groups of alizarin or to one of these atoms and the oxygen atom from the keto group in a complex with three methanol molecules. This means that two electronic transitions need to be taken into account when considering the spectra of the studied complexes. The resulting bond lengths and angles are correlated with the properties of the alkali metal atoms. The molar mass, the atomic radius, and the Pauling electronegativity of studied metals are quite accurate predictors of the geometric properties of hydroxide complexes with alizarin in methanol solution. Graphical abstract The spectra of the neutral and monoanionic form of alizarin together with color changes resulting from addition of different metal hydroxides and represented in CIE color space. PMID:27178415

  1. Antibiofilm efficacy of photoactivated curcumin, triple and double antibiotic paste, 2% chlorhexidine and calcium hydroxide against Enterococcus fecalis in vitro.

    PubMed

    Devaraj, Sharmila; Jagannathan, Nithya; Neelakantan, Prasanna

    2016-01-01

    Root canal disinfection is one of the most important factors governing success of root canal treatment, especially when regenerative strategies are used. This study evaluated the efficacy of 5 intracanal medicaments against mature biofilms of Enterococcus fecalis in vitro: Light activated curcumin, triple antibiotic paste (TAP), double antibiotic paste (DAP), chlorhexidine, calcium hydroxide. Untreated teeth with biofilms served as controls. Confocal microscopy was used to analyse the biofilm mass and percentage of live/dead bacteria within the root canal as well as dentinal tubules. Dentinal shavings obtained from the root canal walls (at 200 and 400 microns depth) were used to quantify the colony forming units/mL. The results showed that light activated curcumin and triple antibiotic paste brought about complete disruption of the biofilm structure (P < 0.05) while chlorhexidine and calcium hydroxide were not significantly different from the control (P > 0.05). Light activated curcumin brought about the highest percentage of dead cells at both depths, but this was not significantly different from triple antibiotic paste (P > 0.05). Curcumin, TAP and DAP brought about a significant reduction of CFU/mL at both depths compared to the control and other groups (P < 0.05). Light activated curcumin brought about a 7 log reduction of bacteria at both depths. PMID:27097667

  2. Revascularization of an Immature Tooth with Apical Periodontitis Using Calcium Hydroxide: A 3-year Follow-up

    PubMed Central

    Silva, Mauro Henrique Chagas; Campos, Celso Neiva; Coelho, Marcelo Santos

    2015-01-01

    Root canal treatment of teeth presenting immature development is a great challenge for both the patient and the professional. The thinness of the root canal walls of immature teeth may lead to root fracture and thus the outcomes of such treatments are uncertain. Revascularization is based on root canal decontamination followed by the induction of blood migration from the periapical tissues and the development of new vascular tissue in the canal space. The principle of disinfection in regenerative endodontics is that it should be achieved with minimum root canal instrumentation; an intracanal medication is used to inhibit bacterial growth and appropriate sealing of the coronal portion is performed. The American Association of Endodontists (AAE) considerations for regenerative endodontics include calcium hydroxide as an alternative intracanal dressing. This material has also been claimed to diminish the possibility of dental staining during revascularization procedures. The relatively new treatment protocol has been widely reported in the last few years; however it should be performed only when other alternatives are not reasonable. This case report presents a 3-year follow-up of a case of revascularization of a maxillary central incisor using calcium hydroxide as a root canal disinfection dressing. PMID:26962377

  3. Antibiofilm efficacy of photoactivated curcumin, triple and double antibiotic paste, 2% chlorhexidine and calcium hydroxide against Enterococcus fecalis in vitro

    PubMed Central

    Devaraj, Sharmila; Jagannathan, Nithya; Neelakantan, Prasanna

    2016-01-01

    Root canal disinfection is one of the most important factors governing success of root canal treatment, especially when regenerative strategies are used. This study evaluated the efficacy of 5 intracanal medicaments against mature biofilms of Enterococcus fecalis in vitro: Light activated curcumin, triple antibiotic paste (TAP), double antibiotic paste (DAP), chlorhexidine, calcium hydroxide. Untreated teeth with biofilms served as controls. Confocal microscopy was used to analyse the biofilm mass and percentage of live/dead bacteria within the root canal as well as dentinal tubules. Dentinal shavings obtained from the root canal walls (at 200 and 400 microns depth) were used to quantify the colony forming units/mL. The results showed that light activated curcumin and triple antibiotic paste brought about complete disruption of the biofilm structure (P < 0.05) while chlorhexidine and calcium hydroxide were not significantly different from the control (P > 0.05). Light activated curcumin brought about the highest percentage of dead cells at both depths, but this was not significantly different from triple antibiotic paste (P > 0.05). Curcumin, TAP and DAP brought about a significant reduction of CFU/mL at both depths compared to the control and other groups (P < 0.05). Light activated curcumin brought about a 7 log reduction of bacteria at both depths. PMID:27097667

  4. Evaluation of the Magnesium Hydroxide Treatment Process for Stabilizing PFP Plutonium/Nitric Acid Solutions

    SciTech Connect

    Gerber, Mark A.; Schmidt, Andrew J.; Delegard, Calvin H.; Silvers, Kurt L.; Baker, Aaron B.; Gano, Susan R.; Thornton, Brenda M.

    2000-09-28

    This document summarizes an evaluation of the magnesium hydroxide [Mg(OH)2] process to be used at the Hanford Plutonium Finishing Plant (PFP) for stabilizing plutonium/nitric acid solutions to meet the goal of stabilizing the plutonium in an oxide form suitable for storage under DOE-STD-3013-99. During the treatment process, nitric acid solutions bearing plutonium nitrate are neutralized with Mg(OH)2 in an air sparge reactor. The resulting slurry, containing plutonium hydroxide, is filtered and calcined. The process evaluation included a literature review and extensive laboratory- and bench-scale testing. The testing was conducted using cerium as a surrogate for plutonium to identify and quantify the effects of key processing variables on processing time (primarily neutralization and filtration time) and calcined product properties.

  5. A NEW PROCESS DEVELOPED FOR SEPARATION OF LIGNIN FROM AMMONIUM HYDROXIDE PRETREATMENT SOLUTIONS

    SciTech Connect

    Sherman, S.; Gorensek, M.; Milliken, C.

    2010-12-14

    A method is described for separating lignin from liquid solutions resulting from the pretreatment of lignocellulosic materials such as switchgrass with ammonium hydroxide. The method involves a sequence of steps including acidification, evaporation, and precipitation or centrifugation that are performed under defined conditions, and results in a relatively pure, solid lignin product. The method is tested on ammonium hydroxide solutions containing lignin extracted from switchgrass. Experimental results show that the method is capable of recovering between 66-95% of dissolved lignin as a precipitated solid. Cost estimates of pilot-scale and industrial-scale expressions of the process indicate that breakeven lignin prices of $2.36/kg and $0.78/kg, respectively, may be obtainable with this recovery method.

  6. Removal of Lead Hydroxides Complexes from Solutions Formed in Silver/Gold: Cyanidation Process

    NASA Astrophysics Data System (ADS)

    Parga, José R.; Martinez, Raul Flores; Moreno, Hector; Gomes, Andrew Jewel; Cocke, David L.

    2014-04-01

    The presence of lead hydroxides in "pregnant cyanide solution" decreases the quality of the Dore obtained in the recovery processes of gold and silver, so it is convenient to remove them. The adsorbent capacity of the low cost cow bone powder was investigated for the removal of lead ions from a solution of lead hydroxide complexes at different initial metal ion concentrations (10 to 50 mg/L), and reaction time. Experiments were carried out in batches. The maximum sorption capacity of lead determined by the Langmuir model was found to be 126.58 mg/g, and the separation factor R L was between 0 and 1, indicating a significant affinity of bone for lead. Experimental data follow pseudo-second order kinetics suggesting chemisorption. It is concluded that cow bone powder can be successfully used for the removal of lead ions, and improves the quality of the silver-gold cyanides precipitate.

  7. Calcium hydroxide nanoparticles for the conservation of cultural heritage: new formulations for the deacidification of cellulose-based artifacts

    NASA Astrophysics Data System (ADS)

    Poggi, G.; Toccafondi, N.; Melita, L. N.; Knowles, J. C.; Bozec, L.; Giorgi, R.; Baglioni, P.

    2014-03-01

    Alkaline earth metal hydroxide nanoparticles dispersions have demonstrated to be efficient for the preservation of cellulose-based artifacts, providing a stable neutral environment and, if in excess, turning into mild alkaline species. New formulations tailored for specific conservation issues have been recently obtained via a solvothermal reaction, starting from bulk metal, and short chain alcohols. Using this synthetic procedure, stable, and high concentrated calcium hydroxide nanoparticles dispersions can be obtained. The characterization of nanoparticles was carried out by dynamic light scattering, transmission electron microscopy and X-ray powder diffraction and showed that the dispersed systems are particularly suitable for the application on porous substrates. In a direct application of this technology, acidic paper and canvas samples were artificially aged after deacidification using calcium hydroxide nanoparticles dispersed in short chain alcohols. Cellulose viscosimetric polymerization degree (DPv), cellulose pyrolysis temperature, and samples' pH were evaluated upon the aging and in terms of protective action arising from the applied treatment. In particular, determinations of DPv clearly showed that the degradation of acidic paper and canvas samples proceeds at higher rates with respect to deacidified samples. These evidences were also confirmed by the thermogravimetric analysis of samples, in which the benefits due to the deacidification treatments are measured in terms of pyrolysis temperature of cellulose. These new formulations of nanoparticles dispersions expand the palette of available tools for the conservation of cellulose-based works of art, such as easel paintings, and manuscripts, potentially opening the way for the intervention on parchment and leather, whose preservation is a particularly challenging task.

  8. Comparison of the adjuvant activity of aluminum hydroxide and calcium phosphate on the antibody response towards Bothrops asper snake venom.

    PubMed

    Olmedo, Hidekel; Herrera, María; Rojas, Leonardo; Villalta, Mauren; Vargas, Mariángela; Leiguez, Elbio; Teixeira, Catarina; Estrada, Ricardo; Gutiérrez, José María; León, Guillermo; Montero, Mavis L

    2014-01-01

    The adjuvanticity of aluminum hydroxide and calcium phosphate on the antibody response in mice towards the venom of the snake Bothrops asper was studied. It was found that, in vitro, most of the venom proteins are similarly adsorbed by both mineral salts, with the exception of some basic phospholipases A2, which are better adsorbed by calcium phosphate. After injection, the adjuvants promoted a slow release of the venom, as judged by the lack of acute toxicity when lethal doses of venom were administered to mice. Leukocyte recruitment induced by the venom was enhanced when it was adsorbed on both mineral salts; however, venom adsorbed on calcium phosphate induced a higher antibody response towards all tested HPLC fractions of the venom. On the other hand, co-precipitation of venom with calcium phosphate was the best strategy for increasing: (1) the capacity of the salt to couple venom proteins in vitro; (2) the venom ability to induce leukocyte recruitment; (3) phagocytosis by macrophages; and (4) a host antibody response. These findings suggest that the chemical nature is not the only one determining factor of the adjuvant activity of mineral salts. PMID:23506358

  9. Analysis of the reaction of subcutaneous tissues in rats and the antimicrobial activity of calcium hydroxide paste used in association with different substances

    PubMed Central

    MIDENA, Raquel Zanin; GARCIA, Roberto Brandão; CAVENAGO, Bruno Cavalini; MARCIANO, Marina Angélica; MINOTTI, Paloma Gagliardi; ORDINOLA-ZAPATA, Ronald; WECKWERTH, Paulo Henrique; de ANDRADE, Flaviana Bombarda; DUARTE, Marco Antonio Hungaro

    2015-01-01

    The aim of this study was to evaluate the subcutaneous tissue response in rats and the antimicrobial activity of intracanal calcium hydroxide dressings mixed with different substances against E. faecalis. Fifty four rats were divided into three experimental groups according to the vehicle in the calcium hydroxide treatment: 0.4% chlorohexidine in propylene glycol (PG), Casearia sylvestris Sw in PG and calcium hydroxide+PG (control group). The pastes were placed into polyethylene tubes and implanted into the subcutaneous tissue. After 7, 14 and 30 days, the samples were processed and histologically evaluated (hematoxylin and eosin). The tissue surface in contact with the material was analyzed, and the quantitative analysis determined the volume density occupied by the inflammatory infiltrate (giant cells, polymorphonuclear cells and mononuclear cells), fibroblasts, collagen fibers and blood vessels. For the antimicrobial analysis, 20 dentin blocks infected with E. faecalis were treated with calcium hydroxide pastes in different vehicles; 0.4% chlorhexidine in PG, PG, extract from Casearia sylvestris Sw in PG and a positive control (infection and without medication) for 7 days. The efficiency of the pastes was evaluated by the live/dead technique and confocal microscopy. The results showed that 0.4% chlorhexidine induced a higher inflammatory response than the other groups. The Casearia sylvestris Sw extract showed satisfactory results in relation to the intensity of the inflammatory response. In the microbiological test, there were no statistical differences between the evaluated intracanal dressings and the percentage of bacterial viability was between 33 and 42%. The control group showed an 86% viability. Antimicrobial components such as chlorhexidine or Casearia sylvestris Sw did not improve the antimicrobial activity against E. faecalis in comparison to the calcium hydroxide+PG treatment. In addition, the incorporation of chlorhexidine in the calcium hydroxide

  10. Analysis of the reaction of subcutaneous tissues in rats and the antimicrobial activity of calcium hydroxide paste used in association with different substances.

    PubMed

    Midena, Raquel Zanin; Garcia, Roberto Brandão; Cavenago, Bruno Cavalini; Marciano, Marina Angélica; Minotti, Paloma Gagliardi; Ordinola-Zapata, Ronald; Weckwerth, Paulo Henrique; Andrade, Flaviana Bombarda de; Duarte, Marco Antonio Hungaro

    2015-10-01

    The aim of this study was to evaluate the subcutaneous tissue response in rats and the antimicrobial activity of intracanal calcium hydroxide dressings mixed with different substances against E. faecalis. Fifty four rats were divided into three experimental groups according to the vehicle in the calcium hydroxide treatment: 0.4% chlorohexidine in propylene glycol (PG),Casearia sylvestris Sw in PG and calcium hydroxide+PG (control group). The pastes were placed into polyethylene tubes and implanted into the subcutaneous tissue. After 7, 14 and 30 days, the samples were processed and histologically evaluated (hematoxylin and eosin). The tissue surface in contact with the material was analyzed, and the quantitative analysis determined the volume density occupied by the inflammatory infiltrate (giant cells, polymorphonuclear cells and mononuclear cells), fibroblasts, collagen fibers and blood vessels. For the antimicrobial analysis, 20 dentin blocks infected with E. faecalis were treated with calcium hydroxide pastes in different vehicles; 0.4% chlorhexidine in PG, PG, extract from Casearia sylvestris Sw in PG and a positive control (infection and without medication) for 7 days. The efficiency of the pastes was evaluated by the live/dead technique and confocal microscopy. The results showed that 0.4% chlorhexidine induced a higher inflammatory response than the other groups. The Casearia sylvestris Sw extract showed satisfactory results in relation to the intensity of the inflammatory response. In the microbiological test, there were no statistical differences between the evaluated intracanal dressings and the percentage of bacterial viability was between 33 and 42%. The control group showed an 86% viability. Antimicrobial components such as chlorhexidine or Casearia sylvestris Sw did not improve the antimicrobial activity against E. faecalis in comparison to the calcium hydroxide+PG treatment. In addition, the incorporation of chlorhexidine in the calcium hydroxide

  11. The influence of aliphatic amines, diamines, and amino acids on the polymorph of calcium carbonate precipitated by the introduction of carbon dioxide gas into calcium hydroxide aqueous suspensions

    NASA Astrophysics Data System (ADS)

    Chuajiw, Wittaya; Takatori, Kazumasa; Igarashi, Teruki; Hara, Hiroki; Fukushima, Yoshiaki

    2014-01-01

    The influence of aliphatic organic additives including amines, diamines and amino acids, on the polymorph of calcium carbonate (CaCO3) precipitated from a calcium hydroxide (Ca(OH)2) suspensions and carbon dioxide gas (CO2) was studied by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The amorphous calcium carbonate, vaterite, aragonite and calcite were observed for the precipitated samples with organic additives. While the precipitation without organic additive, only the stable phase; calcite was obtained. The observed crystal phases were related with the alkyl chain length in the aliphatic part of additives. These results suggested that hydrophobic interactions due to the van der Waals force between organic additives and surface of inorganic precipitates could not be ignored. We concluded that covering or adsorbing of these organic additives on the precipitates surfaces retarded the successive dissolution/recrystallisation process in the aqueous systems. The results revealed that not only the polar interaction from the hydrophilic functional groups, as the former reports proposed, but also the van der Waals interactions from the hydrophobic alkyl groups played the important role in the phase transformation of CaCO3.

  12. Orthophosphate and metaphosphate ion removal from aqueous solution using alum and aluminum hydroxide.

    PubMed

    Georgantas, D A; Grigoropoulou, H P

    2007-11-01

    The removal of orthophosphates (10(-2) kg P m(-3)), condensed phosphates (10(-2) kg P m(-3)), and mixtures of both (5 x 10(-3) kg P m(-3) as orthophosphate and 5 x 10(-3) kg P m(-3) as metaphosphate) in aqueous solution is studied using alum and aluminum hydroxide. The effects of coagulant dose, pH, temperature, aging of aluminum hydroxide, and presence of different ions are investigated. On the basis of the experimental results, alum is much more efficient in phosphorus removal than aluminum hydroxide even if, in both cases, at the conditions studied, the active coagulant form is Al(OH)(3). The differences then could be due to the higher activity of the in situ formed hydroxide. Orthophosphates and metaphosphates seem to have similar behavior vs pH variation: maximum removal is achieved at pH values 5-6 in all cases. On the other hand, in the simultaneous presence of both P forms, orthophosphate and metaphosphate ions have different affinities for the surface sites of aluminum hydroxide, since for both alum and aluminum hydroxide, orthophosphates are preferentially removed compared to metaphosphates, due probably to orientation effects and the charge per P atom. The presence of sodium, potassium, magnesium, sulfate, chloride, and magnesium, at the concentrations studied and for a pH value of 6, does not influence P removal. Temperature variation, between 25 and 60 degrees C, does not affect alum efficiency but both P forms are increasingly removed with increasing temperature, probably due to polymer Al(OH)(3) breaking, producing new surfaces for adsorption. Aging decreases sorption capacity of Al(OH)(3), while crystallites of increasing size are formed. Finally adsorption of both P forms is best described by the Freundlich isotherm [[K(F)=(49.1-69.1) x 10(-3) (m(3)kg(-1))(1/N), 1/N: 0.14-0.19 for T=25-60 degrees C] and [ K(F)=(1.58-2.79) x 10(-3) (m(3)kg(-1))(1/N), 1/N: 2.17-2.47 for T=25-60 degrees C] for orthophosphate and metaphosphate, respectively. PMID

  13. 40 CFR 721.10018 - Calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10018 Calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3). (a) Chemical substance and significant new uses subject to reporting. (1) The...

  14. THE COMPARISON OF SEVERAL STANDARD MATERIALS AND TECHNIQUES FOR THE WARREN-AVERBACH DETERMINATION OF MICRO-STRUCTURE CHARACTERISTICS OF CALCIUM HYDROXIDE SORBENT MATERIALS

    EPA Science Inventory

    The paper gives results of a comparison of several standard materials and techniques for the Warren-Averbach determination of microstructure characteristics of calcium hydroxide--Ca(OH)2--sorbent materials. The comparison is part of an investigation of the injection of dry Ca(OH)...

  15. An in Vitro Evaluation of Antimicrobial Efficacy of 2% Chlorhexidine Gel, Propolis and Calcium Hydroxide Against Enterococcus faecalis in Human Root Dentin

    PubMed Central

    T S, Ashwini; Patil, Chetan R

    2014-01-01

    Aim: To evaluate in vitro the antimicrobial efficacy of 2% Chlorhexidine gel, Propolis and Calcium hydroxide against Enterococcus faecalis in human root dentin. Methodology: One hundred and twenty human extracted anterior teeth were decoronated below CEJ and the apical part of root was removed to obtain 6mm of middle of the root. GG no 3 was used to standardize the internal diameter of root canal. Dentin blocks were infected with E faecalis for 21 d. They were assigned into four groups (n = 30).Group 1, Saline (negative control); Group 2, Propolis; Group 3, 2% CHX; Group 4, Calcium hydroxide, At the end of 1, 3, and 5 days an assessment of microbial cells was carried out at a depth of 400 μm and colony counts were calculated.The data were analysed statistically with one-way analysis of variance followed by Scheffe multiple comparison test (p < 0.05). Results: The number of colony-forming units was significantly lower in all experimental groups compared to the control group – Saline. 2% Chlorhexidinegluconate produced better antimicrobial efficacy (100%) on day 1, 3 and 5. Propolis (66.37%) had greater antimicrobial activity than Calcium hydroxide (50.89%) on day 1 but there was no significant difference in their antimicrobial activities on day 3 and day 5. Conclusion: 2% Chlorhexidine gel showed the maximum antimicrobial activity against E faecalis and Calcium hydroxide the least. Propolis can be used as an effective alternative intracanal medicament. PMID:25584319

  16. Evaluation of the antibacterial activities of calcium hydroxide, chlorhexidine, and camphorated paramonochlorophenol as intracanal medicament. A clinical and laboratory study.

    PubMed

    Barbosa, C A; Gonçalves, R B; Siqueira, J F; De Uzeda, M

    1997-05-01

    The antibacterial activities of camphorated paramonochlorophenol, chlorhexidine, and calcium hydroxide were compared using a clinical and laboratory evaluation. In the clinical experiment, root canals that yielded positive cultures a week after complete chemomechanical preparation and camphorated paramonochlorophenol dressing were medicated with one of the three substances tested. Postmedication samples were taken from the canal 1 week later. In the laboratory experiment, the agar diffusion test was used to evaluate the inhibitory activity of the medicaments against bacteria commonly found in endodontic infections. The results of the clinical evaluation showed that all medicaments were effective in reducing or eliminating the endodontic microbiota, as demonstrated by the incidence of negative cultures. There was no statistically significant difference among the medicaments tested. In the laboratory evaluation, camphorated paramonochlorophenol showed the largest zones of bacterial inhibition against all bacterial strains tested. PMID:9545931

  17. Assessment of the Potential of CFC (Calcium hydroxide Flagyl Ciprofloxacin) for the Rapid Disinfection of Resilon and Gutta-Percha

    PubMed Central

    Hamza, Mariam Omer Bin; Gufran, Khalid

    2015-01-01

    Introduction Obturating materials exposed to the dental operating environment has been shown to be contaminated, making rapid chair side disinfection mandatory to ensure the sterility of the root canals. Objective The purpose of this study was to investigate the effectiveness of CFC (combination of Calcium hydroxide, Flagyl and Ciprofloxacin) for the rapid disinfection of Gutta-percha and Resilon cones. Materials and Methods Seventy new Gutta-percha and Resilon cones were randomly selected, contaminated with Enterococcus faecalis and divided into 4 group according to the irrigant used for disinfection {Group I: 5.25% Sodium Hypochlorite (NaOCl), Group II: MTAD, Group III: 2% Chlorhexidine (CHX), Group IV: CFC (a combination of Calcium hydroxide, Flagyl and Ciprofloxacin)}. All the samples were placed in a centrifuge tube with BHI broth after being washed with sterile water. The samples were then incubated for 7 days at 37oC. Samples were randomly plated on Mac Conkey agar plate and the colony count was recorded and the observations were drawn. Results A 5.25% NaOCl required 1 minute exposure for effective disinfection of all the samples. MTAD could eliminate E.faecalis from gutta-percha samples in 30 seconds whereas it required 1 minute of exposure for Resilon cones. Both 2% CHX and CFC could not disinfect the samples with 1 minute exposure and a minimum of 5 minute exposure was required. Conclusion A 5.25% NaOCl and Biopure MTAD required less chair side time to disinfect all the samples effectively when compared with 2% CHX and CFC. PMID:26557614

  18. Clinical and radiographical evaluation of the healing of large periapical lesions using triple antibiotic paste, photo activated disinfection and calcium hydroxide when used as root canal disinfectant

    PubMed Central

    Varughese, Jolly M.; Thomas, Kunjamma; Abraham, Aby; James, Elizabeth P.; Maroli, Ramesh K.

    2014-01-01

    Objectives: To evaluate clinically and radio graphically, the healing following nonsurgical treatment of periapical lesions when Photo Activated Disinfection(PAD), triple antibiotic paste and calcium hydroxide was used as root canal disinfectant. Material and Methods: Sixty patients (20 for PAD, 20 for triple antibiotic paste, 20 for calcium hydroxide) with periapical lesions in the maxillary and mandibular anterior region were selected from the outpatient section of the Department of Conservative Dentistry & Endodontics, Govt. Dental College, Kozhikode to participate in this study. The patients were selected with a preoperative score of 4 or 5. There were no significant differences for the PAI Scores between the three groups at the start of the experiment .Intracanal disinfection was done in the three groups followed by obturation. The patients recalled at 3,6,12,18 months interval. Results: At 18 months follow up 15 % of cases failed in calcium hydroxide group,5% in triple antibiotic paste and no failure cases were seen in PAD group. Success criteria were divided into strict and loose, while the former had statistically significant p value the latter did not. Kruskal-Wallis Test showed an increased mean value for PDT and a significant change in p value. Bonferroni post hoc test was done to compare if there is any significant change between groups. Only significant change was found between calcium hydroxide and photoactivated disinfection . Conclusion: PAD was more effective intracanal disinfectant at 6,12 and 18 months. Key words:Calcium, hydroxide, photo activated disinfection, triple antibiotic paste, root canal disinfection PMID:25136422

  19. Hydrothermal modification of titanium surface in calcium solutions.

    PubMed

    Hamad, Kenichi; Kon, Masayuki; Hanawa, Takao; Yokoyama, Ken'ichi; Miyamoto, Youji; Asaoka, Kenzo

    2002-05-01

    Hydrothermal modification of a titanium surface in calcium solutions was performed. The apatite precipitation on the modified surface in Hanks' solution, as a simulated body fluid, was evaluated and the surface microstructure changes after the modification were characterized by thin-film X-ray diffractometry (TF-XRD) and X-ray photoelectron spectroscopy (XPS). Hydrothermal modification in CaO solution enhanced the precipitation of apatite on the titanium surface. High pH, high pressure and high temperature of the CaO solution increased the thickness of the surface-modified layer and enhanced the synthesis of calcium titanate which possibly promoted the precipitation of apatite in Hanks' solution. Hydrothermal modification in CaCl2 solution, on the other hand, showed reverse effects. The modification of titanium in CaO solution with hydrothermal treatment is expected to result in excellent osteointegration and can be easily performed by using an autoclave, a clinical apparatus widely used. PMID:11962668

  20. Effect of cetyl trimethyl ammonium bromide concentration on structure, morphology and carbon dioxide adsorption capacity of calcium hydroxide based sorbents

    NASA Astrophysics Data System (ADS)

    Hlaing, Nwe Ni; Vignesh, K.; Sreekantan, Srimala; Pung, Swee-Yong; Hinode, Hirofumi; Kurniawan, Winarto; Othman, Radzali; Thant, Aye Aye; Mohamed, Abdul Rahman; Salim, Chris

    2016-02-01

    Calcium hydroxide (Ca(OH)2) has been proposed as an important material for industrial, architectural, and environmental applications. In this study, calcium acetate was used as a precursor and cetyl trimethyl ammonium bromide (CTAB) was used as a surfactant to synthesize Ca(OH)2 based adsorbents for carbon dioxide (CO2) capture. The effect of CTAB concentration (0.2-0.8 M) on the structure, morphology and CO2 adsorption performance of Ca(OH)2 was studied in detail. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), BET surfaced area and thermogravimetry-differential thermal analysis (TG-DTA) techniques. The phase purity, crystallite size, Brunauer-Emmett-Teller (BET) surface area and CO2 adsorption performance of Ca(OH)2 precursor adsorbents were significantly increased when the concentration of CTAB was increased. XRD results showed that pure Ca(OH)2 phase was obtained at the CTAB concentration of 0.8 M. TGA results exhibited that 0.8 M of CTAB-assisted Ca(OH)2 precursor adsorbent possessed a residual carbonation conversion of ∼56% after 10 cycles.

  1. Effect of Calcium Hydroxide on the Push-out Bond Strength of Endodontic Biomaterials in Simulated Furcation Perforations

    PubMed Central

    Ghasemi, Negin; Reyhani, Mohammad Forough; Salem Milani, Amin; Mokhtari, Hadi; Khoshmanzar, Faezeh

    2016-01-01

    Introduction: The aim of this in vitro study was to evaluate the effect of calcium hydroxide (CH) on push-out bond strength of white mineral trioxide aggregate (WMTA) and calcium-enriched mixture (CEM) cement in simulated furcation perforations. Methods and Materials: Furcation perforations, measuring 1.3 mm in diameter and 2 mm in height, were created in 80 human mandibular first molars. The teeth were then divided into 4 groups (n=20). In groups 1 and 3 CH was placed in the perforation for one week, before placement of WMTA and CEM. In groups 2 and 4 perforations were repaired without placement of CH. In groups 1 and 2 the perforation sites were repaired with WMTA and CEM cement was used in groups 3 and 4. After 7 days, the push-out test was carried out using a universal testing machine. Data were analyzed with two-way ANOVA. The level of significance was set at 0.05. Results: The maximum and minimum bond strength values were recorded in the WMTA/CH (13.08±1.8 MPa) and CEM cement groups (8.03±0.98 MPa), respectively. There were significant differences in resistance to dislodgement between the WMTA/CH and other groups (P<0.05). Conclusion: Placement of CH before placement of WMTA in furcation perforation improves the push-out bond strength of this material. PMID:27141214

  2. Early age hydration of calcium sulfoaluminate (synthetic ye'elimite, C{sub 4}A{sub 3}S{sup ¯}) in the presence of gypsum and varying amounts of calcium hydroxide

    SciTech Connect

    Hargis, Craig W.; Kirchheim, Ana Paula; Monteiro, Paulo J.M.; Gartner, Ellis M.

    2013-06-15

    Suspensions of synthetic ye'elimite (C{sub 4}A{sub 3}S{sup ¯}) in a saturated gypsum (CS{sup ¯}H{sub 2}) and calcium hydroxide (CH) solution were examined in-situ in a wet cell by soft X-ray transmission microscopy and ex-situ by scanning electron microscopy. The most voluminous hydration product observed was ettringite. Ettringite commonly displayed acicular, filiform, reticulated, and stellate crystal habits. Additionally, pastes with C{sub 4}A{sub 3}S{sup ¯}, 15% CS{sup ¯}H{sub 2}, and varying amounts of CH were prepared and examined with X-ray diffraction (XRD) and isothermal calorimetry. The XRD experiments showed that increasing CH content caused more solid solution (SO{sub 4}{sup 2−}/OH{sup −}) AFm phases to form at early ages (< 1 d) and more monosulfate to form at later ages (> 1 d). Calorimetry indicated that the increased production of solid solution AFm was accompanied with an increase in the initial (< 30 min) rate of heat evolution, and increasing CH generally reduced the time till the second maximum rate of heat evolution due to the formation of ettringite and monosulfate.

  3. Laboratory Synthesized Calcium Oxide and Calcium Hydroxide Grains: A Candidate to Explain the 6.8 Micron Band

    NASA Technical Reports Server (NTRS)

    Kimura, Yuki; Nuth, Joseph A., III

    2005-01-01

    We will demonstrate that CaO and Ca(OH)2 are excellent candidates to explain the 6.8 microns feature, which is one of the most obscure features in young stellar objects. We discuss the condensation of CaO grains and the potential formation of a Ca(OH)2 surface layer. The infrared spectra of these grains are compared with the spectra of fifteen young stellar objects. We note that CaO-rich grains are seen in all meteoritic CAIs (calcium-aluminum-rich inclusions) and the 6.8 micron feature has only been observed in young stellar objects. Therefore, we consider CaO grains to be a plausible candidate to explain the 6.8 microns feature and hypothesize that they are produced in the hot interiors of young stellar environments.

  4. Effect of controlled deactivation on the thermochemical characteristics of hydrogen adsorption on skeletal nickel from sodium hydroxide-water solutions

    NASA Astrophysics Data System (ADS)

    Prozorov, D. A.; Lukin, M. V.; Ulitin, M. V.

    2013-04-01

    Differential heats of adsorption in a wide range of surface coverage and maximum amounts of adsorbed hydrogen are determined by adsorption calorimetry on partially deactivated skeletal nickel from aqueous solutions of sodium hydroxide. The effect of the composition of solutions on the values of limiting adsorption and adsorption equilibria of individual forms of hydrogen is shown.

  5. Study on anisotropic silicon etching characteristics in various surfactant-added tetramethyl ammonium hydroxide water solutions

    NASA Astrophysics Data System (ADS)

    Yang, Chii-Rong; Yang, Cheng-Hao; Chen, Po-Ying

    2005-11-01

    Three ion-typed surfactants, including anionic sodium dihexyl sulfosuccinate (SDSS), cationic ammonium salt of poly(ethylene glycol) (ASPEG) and non-ionic poly(ethylene glycol) (PEG), were added to 10 wt% tetramethyl ammonium hydroxide water (TMAHW) solutions to evaluate the silicon anisotropic etching properties of the (1 0 0) silicon plane without agitation and no isopropyl alcohol (IPA) additive. The results indicate that the wetting capacity of the etchants cause the efficacies of the etchants on the roughness reduction to follow the order cationic ASPEG, non-ionic PEG, pure solution and anionic SDSS in TMAHW solutions, especially at high etching temperatures. Moreover, the chemical activities of the etchants cause the efficacies of the etchants on the etching rates to follow the order anionic SDSS, pure solution, cationic ASPEG and non-ionic PEG in TMAHW solutions at a given etching temperature. The cationic ASPEG has a reasonable etching rate of 0.7 µm min-1 and the lowest surface roughness of 4 nm in TMAHW solutions at an etching temperature of 100 °C. ASPEG and PEG in TMAHW solutions markedly affect aluminum passivation. The undercutting of the convex corners in PEG-added TMAHW solutions can be drastically reduced without using corner compensation; the undercutting ratio obtained using a PEG surfactant is about 45% lower than that obtained in pure TMAHW solution. This finding reveals that non-ionic PEG should be added to TMAHW solutions when accurate profiles are required without extremely deep etching. This study also demonstrated that non-ionic PEG is more appropriate than IPA for anisotropic silicon TMAHW etching.

  6. Effect of aging on aluminum hydroxide complexes in dilute aqueous solutions

    USGS Publications Warehouse

    Smith, Ross Wilbert; Hem, John David

    1972-01-01

    Aqueous aluminum solutions containing 4?10 -5 mole/liter aluminum and a constant total ionic strength of 10 -2, but with varying ratios of hydroxide to aluminum (OH:Al), were prepared. Progress of these solutions toward equilibrium conditions over aging periods of as much as 2 years was studied by determining the composition and pH of the solutions at various time intervals. The solutions, after mixing, were supersaturated with respect to both crystalline and amorphous forms of aluminum oxides and aluminum hydroxides. The compositions of the solutions were determined by use of a timed colorimetric analytical procedure which allowed the estimation of three separate forms of aluminum that have been designated Al a, Al b, and Al c. Form Al a appeared to be composed of monomeric species such as Al(H20)6+3, Al(OH)(H20)5+2, Al(OH)2(H20)4 +I and Al(OH)4-. Form Al b was polynuclear material containing perhaps 20-400 aluminum atoms per structure. It appeared to be a metastable material. Form Al c was composed of relatively large, microcrystalline, clearly solid AI(OH)3 particles. For each OH :Al ratio, the concentration of Al a remained constant with aging time, Al b decreased, and Al c increased. It appeared that Al b particles were increasing in size and ultimately were converted to Al c particles. After a few weeks' aging, Al c particles had the structure of gibbsite. In all solutions, equilibrium was only very slowly achieved, and the time required depended on the OH:Al ratio and how rapidly the solution was initially prepared (mixing time). Lower ratios caused a slower approach to equilibrium; sometimes equilibrium was not achieved even after several years' aging. The more slowly base was initially added (to obtain the proper OH:Al ratio), the more slowly was equilibrium approached. Ultimate equilibrium values of dissolved aluminum concentration and pH were consistent with known thermodynamic data on monomeric aluminum species. From data determined during the aging

  7. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    DOEpatents

    Rau, Gregory Hudson

    2014-07-01

    A system for forming metal hydroxide from a metal carbonate utilizes a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide.

  8. Predictive Mechanical Characterization of Macro-Molecular Material Chemistry Structures of Cement Paste at Nano Scale - Two-phase Macro-Molecular Structures of Calcium Silicate Hydrate, Tri-Calcium Silicate, Di-Calcium Silicate and Calcium Hydroxide

    NASA Astrophysics Data System (ADS)

    Padilla Espinosa, Ingrid Marcela

    Concrete is a hierarchical composite material with a random structure over a wide range of length scales. At submicron length scale the main component of concrete is cement paste, formed by the reaction of Portland cement clinkers and water. Cement paste acts as a binding matrix for the other components and is responsible for the strength of concrete. Cement paste microstructure contains voids, hydrated and unhydrated cement phases. The main crystalline phases of unhydrated cement are tri-calcium silicate (C3S) and di-calcium silicate (C2S), and of hydrated cement are calcium silicate hydrate (CSH) and calcium hydroxide (CH). Although efforts have been made to comprehend the chemical and physical nature of cement paste, studies at molecular level have primarily been focused on individual components. Present research focuses on the development of a method to model, at molecular level, and analysis of the two-phase combination of hydrated and unhydrated phases of cement paste as macromolecular systems. Computational molecular modeling could help in understanding the influence of the phase interactions on the material properties, and mechanical performance of cement paste. Present work also strives to create a framework for molecular level models suitable for potential better comparisons with low length scale experimental methods, in which the sizes of the samples involve the mixture of different hydrated and unhydrated crystalline phases of cement paste. Two approaches based on two-phase cement paste macromolecular structures, one involving admixed molecular phases, and the second involving cluster of two molecular phases are investigated. The mechanical properties of two-phase macromolecular systems of cement paste consisting of key hydrated phase CSH and unhydrated phases C3S or C2S, as well as CSH with the second hydrated phase CH were calculated. It was found that these cement paste two-phase macromolecular systems predicted an isotropic material behavior. Also

  9. New uses for calcium chloride solution as a mounting medium.

    PubMed

    Herr, J M

    1992-01-01

    Fresh cross sections of stems (Psilotum nudum, Coleus blumei, and Pelargonium peltatum) and roots (Setcreasea purpurea) 120 microns thick were fixed in FPA50 (formalin: propionic acid: 50% ethanol, 5:5:90, v/v) for 24 hr and stored in 70% ethanol. The sections were transferred to water and then to 1% phloroglucin in 20% calcium chloride solution plus either hydrochloric, nitric, or lactic acid in the following ratios of phloroglucin-CaCl2 solution:acid: 25:4, 20:2, or 15:5. The sections were mounted on slides either in one of the three mixtures or in fresh 20% calcium chloride solution. A rapid reaction of the acid-phloroglucin with lignin produced a deep red color in tracheary elements and an orange-red color in sclerenchyma. Fixed and stored leaf pieces from Nymphaea odorata were autoclaved in lactic acid, washed in two changes of 95% ethanol, transferred to water, and treated with the three acid-phloroglucin-calcium chloride mixtures. The abundant astrosclereids stained an orange-red color similar to that of sclerenchyma in the sections. In addition, a new method is reported for specifically staining lignified tissues. When sections or leaf pieces are stained in aqueous 0.05% toluidine blue O, then placed in 20% calcium chloride solution, all tissues destain except those with lignified or partially lignified cell walls. Thus, toluidine blue O applied as described becomes a reliable specific test for lignin comparable to the acid-phloroglucin test. PMID:1377501

  10. Effect of addition of lycopene to calcium hydroxide and chlorhexidine as intracanal medicament on fracture resistance of radicular dentin at two different time intervals: An in vitro study

    PubMed Central

    Madhusudhana, Koppolu; Archanagupta, Kasamsetty; Suneelkumar, Chinni; Lavanya, Anumula; Deepthi, Mandava

    2015-01-01

    Background: Long-term use of intracanal medicaments such as calcium hydroxide (CH) reduces the fracture resistance of dentin. The present study was undertaken to evaluate the fracture resistance of radicular dentin on long-term use of CH, chlorhexidine (CHX) with lycopene (LP). Aim: To compare the fracture resistance of radicular dentin when intracanal medicaments such as CH, CHX with LP were used for 1-week and 1-month time interval. Settings and Design: Sixty single-rooted extracted human permanent premolars were collected, and complete instrumentation was done. Samples were divided into three groups based on intracanal medicament used. Materials and Methods: Group 1 - no medicament was placed (CON), group 2 - mixture of 1.5 g of CH and 1 ml of 2% CHX (CHCHX), group 3 - mixture of 1.5 g of CH, 1 ml of CHX and 1 ml of 5% LP solution (CHCHXLP). After storage period of each group for 1-week and 1-month, middle 8 mm root cylinder was sectioned and tested for fracture resistance. Statistical Analysis: Results were analyzed using paired t-test. Results: At 1-month time interval, there was a statistically significant difference in fracture resistance between CHCHX and CHCHXLP groups. Conclusion: Addition of LP has not decreased the fracture resistance of radicular dentin after 1-month. PMID:26069405

  11. Chemically and compositionally modified solid solution disordered multiphase nickel hydroxide positive electrode for alkaline rechargeable electrochemical cells

    DOEpatents

    Ovshinsky, Stanford R.; Corrigan, Dennis; Venkatesan, Srini; Young, Rosa; Fierro, Christian; Fetcenko, Michael A.

    1994-01-01

    A high capacity, long cycle life positive electrode for use in an alkaline rechargeable electrochemical cell comprising: a solid solution nickel hydroxide material having a multiphase structure that comprises at least one polycrystalline .gamma.-phase including a polycrystalline .gamma.-phase unit cell comprising spacedly disposed plates with at least one chemical modifier incorporated around the plates, the plates having a range of stable intersheet distances corresponding to a 2.sup.+ oxidation state and a 3.5.sup.+, or greater, oxidation state; and at least one compositional modifier incorporated into the solid solution nickel hydroxide material to promote the multiphase structure.

  12. Mineral trioxyde aggregate versus calcium hydroxide in apexification of non vital immature teeth: Study protocol for a randomized controlled trial

    PubMed Central

    2011-01-01

    Background Pulp necrosis is one of the main complications of dental trauma. When it happens on an immature tooth, pulp necrosis implies a lack of root maturation and apical closure. A therapy called apexification is required to induce the formation of a calcified apical barrier allowing a permanent and hermetic root filling. The aim of this prospective randomized clinical trial is to compare Mineral Trioxide Aggregate(MTA)with Calcium Hydroxide(CH)as materials used to induce root-end closure in necrotic permanent immature incisors. Methods/Design This study, promoted by AP-HP, was approved by the ethics committee(CPP Paris Ile de France IV). 34 children aged from 6 to 18 years and presenting a non-vital permanent incisor are selected. Prior to treatment, an appropriate written consent has to be obtained from both parents and from children. Patients are then randomly assigned to either the MTA(experimental)or CH(control)groups. Recalls are performed after 3, 6 and 12 months to determine the presence or absence of a calcified apical barrier through the use of clinical and radiographic exams. Additional criteria such as clinical symptoms, apical radiolucencies, periapical index(PAI)are also noted. Trial registration ClinicalTrials.gov no. NCT00472173 (First inclusion: May 10, 2007; Last inclusion: April 23, 2009; study completed: April 15, 2010) PMID:21752247

  13. Effect of treating sugarcane bagasse with urea and calcium hydroxide on feed intake, digestibility, and rumen fermentation in beef cattle.

    PubMed

    Gunun, Nirawan; Wanapat, Metha; Gunun, Pongsatorn; Cherdthong, Anusorn; Khejornsart, Pichad; Kang, Sungchhang

    2016-08-01

    Four beef cattle with initial body weight of 283 ± 14 kg were randomly allocated according to a 4 × 4 Latin square design to study on the effect of feeding sugarcane bagasse (SB) treated with urea and/or calcium hydroxide (Ca(OH)2) on feed intake, digestibility, and rumen fermentation. The treatments were as follows: rice straw (RS), untreated SB (SB), 4 % urea-treated SB (SBU), and 2 % urea + 2 % Ca(OH)2-treated SB (SBUC), respectively. The results revealed that cattle fed with SBU and SBUC had higher feed intake and apparent digestibility. Ammonia nitrogen and blood urea nitrogen were increased in cattle fed with SB as roughage source (P < 0.05). Feeding SBU and SBUC to cattle resulted in higher propionic acid and lower acetic acid, acetic to propionic ratio, and methane production (P < 0.05). Moreover, the number of fungi was increased in SBU- and SBUC-fed groups while protozoa population was unchanged. This study concluded that the nutritive value of SB was improved by urea and/or Ca(OH)2 treatment, and feeding treated SB could increase feed intake, digestibility, and rumen fermentation. This study suggested that SB treated with 2 % urea + 2 % Ca(OH)2 could be used as an alternative roughage source for ruminant feeding. PMID:27139254

  14. The effects of calcium hydroxide on hydrogen chloride emission characteristics during a simulated densified refuse-derived fuel combustion process.

    PubMed

    Chiang, Kung-Yuh; Jih, Jer-Chyuan; Lin, Kae-Long

    2008-08-30

    This study investigated the effects of different calcium hydroxide (Ca(OH)(2)) addition methods on the potential for hydrogen chloride (HCl) formation in a simulated densified refuse-derived fuel (RDF-5) with single metal combustion system. These experiments were conducted at 850 degrees C with the Ca(OH)(2) spiked in the RDF-5 production or injection in the flue gas treatment system. The results indicated that the potential for HCl formation was decreased significantly by Ca(OH)(2) spiked in the RDF-5 production or injection in the flue gas treatment system. However, the Ca(OH)(2) injection method in the flue gas for HCl emission reduction was better than other method. According to the relationship between the HCl emission and amount of Ca(OH)(2) injected or spiked, it is interesting to find that when the Ca(OH)(2) injected or spiked ranged from 0% to 5%, the potential for HCl formation in the single metal combustion system decreases significantly with increasing Ca(OH)(2) injected or spiked ratio. A corresponding increase in the amount of CaCl(2) partitioned to the fly ash was observed. However, with the ratio of Ca(OH)(2) higher than 5%, the amount of HCl formation showed that no further significant variation occurred with increasing Ca(OH)(2) spiked ratio. PMID:18272287

  15. Retrievabilty of calcium hydroxide intracanal medicament with Chitosan from root canals: An in vitro CBCT volumetric analysis

    PubMed Central

    Vineeta, Nikhil; Gupta, Sachin; Chandra, Aditi

    2014-01-01

    Aim: This study compared the amount of aqueous-based and oil-based calcium hydroxide [Ca(OH)2 ] remaining in the canal, after removal with two different chelators 17% EDTA and 0.2% Chitosan in combination with ultrasonic agitation. Materials and Methods: Cleaning and shaping of root canals of 28 mandibular premolar was done and canals were filled either with Metapex or Ca(OH)2 mixed with distilled water. Volumetric analysis was performed utilizing cone beam-computed tomography (CBCT) after 7 days of incubation. Ca(OH)2 was removed using either 17% EDTA or 0.2% Chitosan in combination with ultrasonic agitation. Volumetric analysis was repeated and percentage difference was calculated and statistically analysed using Kruskal-Wallis and Mann-Whitney U test. Results: Both the chelators failed to remove aqueous-based as well as oil-based Ca(OH)2 completely from the root canal. Aqueous-based Ca(OH)2 was easier to be removed than oil-based Ca(OH)2. 0.2% Chitosan was significantly more effective for removal of oil-based Ca(OH)2 (P < 0.01) while both 17% EDTA and 0.2% Chitosan were equally effective in removing aqueous-based Ca(OH)2 . Conclusion: Combination of 0.2% Chitosan and ultrasonic agitation results in lower amount of Ca(OH)2 remnants than 17% EDTA irrespective of type of vehicle present in the mix. PMID:25298647

  16. Structural properties and adsorption capacity of holocellulose aerogels synthesized from an alkali hydroxide-urea solution

    NASA Astrophysics Data System (ADS)

    Kwon, Gu-Joong; Kim, Dae-Young; Hwang, Jae-Hyun; Kang, Joo-Hyon

    2014-05-01

    A tulip tree was used to synthesize a holocellulose aerogel from an aqueous alkali hydroxide-urea solution with the substitution of an organic solvent followed by freeze-drying. For comparison, the synthesized holocellulose aerogels were divided into two groups according to the source of the hydrogel, an upper suspended layer and a bottom concentrated layer of the centrifuged solution of cellulose and NaOH/urea solvents. We investigated the effects of the temperature of the pre-cooled NaOH/urea solution ( i.e., dissolution temperature) on the pore structure and the adsorption capacity of the holocellulose aerogel. A nano-fibrillar network structure of the holocellulose aerogel was observed, with little morphological difference in pore structure for different dissolution temperatures. Both micropores and mesopores were observed in the holocellulose aerogel. The specific surface area of the holocellulose aerogel was generally greater at lower dissolution temperatures. In a series of adsorption tests using methylene blue, the holocellulose aerogel showed the greatest adsorption capacity at the lowest dissolution temperature tested (-2°C). However, the dissolution temperature generally had little effect on the adsorption capacity. The holocellulose aerogel produced from the upper suspended layer of the centrifuged hydrogel solution showed a greater porosity and adsorption capacity than the one produced from the bottom concentrated layer. Overall, the aerogel made by utilizing a delignified tulip tree display a high surface area and a high adsorption property, indicating its possible application in eco-friendly adsorption materials.

  17. Effect of calcium hydroxide and triple antibiotic paste as intracanal medicaments on the incidence of inter-appointment flare-up in diabetic patients: An in vivo study

    PubMed Central

    Pai, Swathi; Vivekananda Pai, A. R.; Thomas, Manuel S.; Bhat, Vishal

    2014-01-01

    Aim: To evaluate and compare the effect of antibacterial intracanal medicaments on inter-appointment flare-up in diabetic patients. Materials and Methods: Fifty diabetic patients requiring root canal treatment were assigned into groups I, II, and III. In group I, no intracanal medicament was placed. In groups II and III, calcium hydroxide and triple antibiotic pastes were placed as intracanal medicaments, respectively. Patients were instructed to record their pain on days 1, 2, 3, 7, and 14. Inter-appointment flare-up was evaluated using verbal rating scale (VRS). Results: Overall incidence of inter-appointment flare-up among diabetic patients was found to be 16%. In group I, 50% of the patients and in group II, 15% of the patients developed inter-appointment flare-up. However, no patients in group III developed inter-appointment flare-up. The comparison of these results was found to be statistically significant (P = 0.002; χ2 = 12.426). However, with respect to intergroup comparison, only the difference between groups I and III was found to be statistically significant (P = 0.002; χ2 = 12.00). Conclusions: Calcium hydroxide and triple antibiotic paste are effective for managing inter-appointment flare-ups in diabetic patients. Triple antibiotic paste is more effective than calcium hydroxide in preventing the occurrence of flare-up in diabetic patients. PMID:24944440

  18. Microelectrophoretic study of calcium oxalate monohydrate in macromolecular solutions

    NASA Technical Reports Server (NTRS)

    Curreri, P. A.; Onoda, G. Y., Jr.; Finlayson, B.

    1987-01-01

    Electrophoretic mobilities were measured for calcium oxalate monohydrate (COM) in solutions containing macromolecules. Two mucopolysaccharides (sodium heparin and chondroitin sulfate) and two proteins (positively charged lysozyme and negatively charged bovine serum albumin) were studied as adsorbates. The effects of pH, calcium oxalate surface charge (varied by calcium or oxalate ion activity), and citrate concentration were investigated. All four macromolecules showed evidence for adsorption. The macromolecule concentrations needed for reversing the surface charge indicated that the mucopolysaccharides have greater affinity for the COM surface than the proteins. Citrate ions at high concentrations appear to compete effectively with the negative protein for surface sites but show no evidence for competing with the positively charged protein.

  19. Electrochemical cell with calcium anode

    DOEpatents

    Cooper, John F.; Hosmer, Pamela K.; Kelly, Benjamin E.

    1979-01-01

    An electrochemical cell comprising a calcium anode and a suitable cathode in an alkaline electrolyte consisting essentially of an aqueous solution of an hydroxide and a chloride. Specifically disclosed is a mechanically rechargeable calcium/air fuel cell with an aqueous NaOH/NaCl electrolyte.

  20. Polymerization of calcium caseinates solutions induced by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Lacroix, M.; Jobin, M.; Mezgheni, E.; Srour, M.; Boileau, S.

    1998-06-01

    Solutions of calcium caseinate (5%) combined with propylene glycol (PG) or triethylene glycol(TEG) (0, 2.5% and 5%) and used for the development of edible films and coatings, were irradiated at doses between 0 to 128 kGy. Solutions were chromatographed through toyopearl HW 55F resin to observe the effect of irradiation on cross-link reactions. In unirradiated calcium caseinate solutions, two peaks could be observed (fractions 30 and 37) while samples irradiated at 64 kGy and 128 kGy showed one shifted peak at fraction 32 and 29 respectively. No effect of the plasticizers was observed. According to proteins standards of knowed molecular weights, the molecular weight of calcium caseinate increased approximately 10 times when irradiated at 128 kGy and 5 times when irradiated at 64 kGy. The physico-chemical properties of bio-films prepared with the irradiated solutions, demonstrated that tensile strength at break increased with increase of irradiation dose. A maximum dose was obtained at 16 kGy.

  1. Removal of trivalent chromium from aqueous solution using aluminum oxide hydroxide.

    PubMed

    Bedemo, Agaje; Chandravanshi, Bhagwan Singh; Zewge, Feleke

    2016-01-01

    Water is second most essential for human being. Contamination of water makes it unsuitable for human consumption. Chromium ion is released to water bodies from various industries having high toxicity which affects the biota life in these waters. In this study aluminum oxide hydroxide was tested for its efficiency to remove trivalent chromium from aqueous solutions through batch mode experiments. Chromium concentrations in aqueous solutions and tannery waste water before and after adsorption experiments were determined using flame atomic absorption spectrometry. The effects of pH, contact time, initial concentration and adsorbent dosage on the adsorption of Cr(III) were studied. The study revealed that more than 99 % removal of Cr(III) was achieved over wide range of initial pH (3-10). The optimum conditions for the removal of Cr(III) were found to be at pH 4-6 with 40 g/L adsorbent dose at 60 min of contact time. The adsorption capacity was assessed using Langmuir and Freundlich isotherms. The equilibrium data at varying adsorbent dose obeyed the two isotherms. The adsorbent was found to be efficient for the removal of Cr(III) from tannery waste effluent. PMID:27547663

  2. The efficacy of the self-adjusting file and ProTaper for removal of calcium hydroxide from root canals

    PubMed Central

    FARIA, Gisele; KUGA, Milton Carlos; RUY, Alessandra Camila; ARANDA-GARCIA, Arturo Javier; BONETTI-FILHO, Idomeo; GUERREIRO-TANOMARU, Juliane Maria; LEONARDO, Renato Toledo

    2013-01-01

    Objective The goal of this study was to evaluate the efficacy of the Self-Adjusting File (SAF) and ProTaper for removing calcium hydroxide [Ca(OH)2] from root canals. Material and Methods Thirty-six human mandibular incisors were instrumented with the ProTaper system up to instrument F2 and filled with a Ca(OH)2-based dressing. After 7 days, specimens were distributed in two groups (n=15) according to the method of Ca(OH)2 removal. Group I (SAF) was irrigated with 5 mL of NaOCl and SAF was used for 30 seconds under constant irrigation with 5 mL of NaOCl using the Vatea irrigation device, followed by irrigation with 3 mL of EDTA and 5 mL of NaOCl. Group II (ProTaper) was irrigated with 5 mL of NaOCl, the F2 instrument was used for 30 seconds, followed by irrigation with 5 mL of NaOCl, 3 mL of EDTA, and 5 mL of NaOCl. In 3 teeth Ca(OH)2 was not removed (positive control) and in 3 teeth canals were not filled with Ca(OH)2 (negative control). Teeth were sectioned and prepared for the scanning electron microscopy. The amounts of residual Ca(OH)2 were evaluated in the middle and apical thirds using a 5-score system. Results None of the techniques completely removed the Ca(OH)2 dressing. No difference was observed between SAF and ProTaper in removing Ca(OH)2 in the middle (P=0.11) and the apical (P=0.23) thirds. Conclusion The SAF system showed similar efficacy to rotary instrument for removal of Ca(OH)2 from mandibular incisor root canals. PMID:24037074

  3. Structural and nano-mechanical properties of Calcium Silicate Hydrate (C-S-H) formed from alite hydration in the presence of sodium and potassium hydroxide

    SciTech Connect

    Mendoza, Oscar; Giraldo, Carolina; Camargo, Sergio S.

    2015-08-15

    This research evaluates the effect of sodium and potassium hydroxide on the structure and nano-mechanical properties of Calcium Silicate Hydrate (C-S-H) formed from the hydration of pure alite. Monoclinic (MIII) alite was synthesized and hydrated, using water-to-alite ratios of 0.5 and 0.6 and additions of 10% NaOH and KOH by weight of alite. Based on results of X-ray diffraction, isothermal calorimetry, thermogravimetric analysis, Nuclear Magnetic Resonance and nanoindentation, two different effects of the alkaline hydroxides on the hydration reaction of alite, both at early and later ages, can be identified: (i) a differentiated hydration process, attributed to an enhancement in calcium hydroxide (CH) precipitation and a stimulation of the C-S-H nuclei; and (ii) an increase in the elastic modulus of the C-S-H aggregations, attributed to an electrostatic attraction between positive charges from the alkaline cations and negative charges from the C-S-H structure.

  4. [Adsorption of Phosphate by Lanthanum Hydroxide/Natural Zeolite Composites from Low Concentration Phosphate Solution].

    PubMed

    Lin, Jian-wei; Wang, Hong; Zhan, Yan-hui; Chen, Dong-mei

    2016-01-15

    A series of composites of lanthanum hydroxide/natural zeolite ( La( OH) 3/NZ composites) were prepared by co-precipitation method, and these composites were used as adsorbents to remove phosphate from aqueous solution. The phosphate adsorption capacities of different composites prepared with different precipitated pH values were compared in batch mode. The adsorption characteristics of phosphate from aqueous solution on the La(OH)3/NZ composite prepared with the precipitated pH value of 11 was investigated using batch experiments. The results showed that the La(OH)3/NZ composite prepared with the precipitated pH values of 5-7 and 13 had a low adsorption capacity for phosphate in aqueous solution, while the La( OH) 3/NZ composites prepared with the precipitated pH values of 9-12 exhibited much higher phosphate adsorption capacity. The phosphate adsorption capacity of the La (OH)3/NZ composite increased with the increase of the precipitated pH value from 9 to 11, but remained basically unchanged with the increase of the precipitated pH value from 11 to 12. The equilibrium adsorption data of phosphate from aqueous solution on the La ( OH ) 3/NZ composite prepared with the precipitated pH value of 11 could be described by the Langmuir isotherm model with the predicted maximum phosphate adsorption of 44 mg x g(-1) (phosphate solution pH 7 and 30 degrees C). The kinetic data of phosphate adsorption from low concentration phosphate solution on the La(OH)3/NZ composite prepared with the precipitated pH value of 11 well followed a pseudo-second-order model. The presence of Cl- and SO4(2-) in low concentration phosphate solution had no negative effect on phosphate adsorption onto the La(OH)3/NZ composite prepared with the precipitated pH value of 11, while the presence of HCO3- slightly inhibited the adsorption of phosphate. Coexisting humic acid had a negative effect on the adsorption of phosphate at low concentration on the La(OH)3/NZ composite prepared with the

  5. Enhancing removal efficiency of anionic dye by combination and calcination of clay materials and calcium hydroxide.

    PubMed

    Vimonses, Vipasiri; Jin, Bo; Chow, Christopher W K; Saint, Chris

    2009-11-15

    We explored a feasible approach to enhance removal capacity of three natural clays for removing anionic dye from aqueous solution. Optimal mixing proportions of the clay materials and temperature range for the calcination were investigated. We found that the removal efficiency can be improved significantly when the clay materials were mixed at certain ratio with the addition of lime and the mixed clay materials were calcined 100-300 degrees C. Batch experiments were conducted to study the effects of initial concentration, material dosage, contact time and pH on dye elimination. Kinetic study showed that more than 80% dye removal took place in 5 min. A high removal capacity (>575 mg g(-1)) of the mixed clay materials can be achieved at a low adsorbent dose. The mixed clay materials can be easily recovered by thermal treatment. The recovered mixtures demonstrated an enhanced removal capability after a few cycles of removal and regeneration. The results revealed that use of these clay materials could develop a low-cost treatment process for industrial wastewater. PMID:19604637

  6. Removal of ash from Indian Assam coking coal using sodium hydroxide and acid solutions

    SciTech Connect

    Kumar, M.; Shankar, R.H.

    2000-03-01

    Mineral matter (ash) removal from Assam coking coal by leaching with different concentrations of sodium hydroxide and acid (HCl, H{sub 2}SO{sub 4}, HNO{sub 3}, and HF) solutions has been investigated at a temperature of 75 C. The parameters tested were concentration of NaOH, type of acid, concentration of acids, and number of acid leaching steps. Total ash removed increased with increase of NaOH and acid concentrations up to the range studied. For the same experimental conditions, treatment of caustic leached coal in HCl acid resulted in better demineralization than in H{sub 2}SO{sub 4} or HNO{sub 3} acid. In the NaOH-HNO{sub 3} leaching method, a higher concentration (>20%) of HNO{sub 3} acid had an adverse effect on the de-ashing of coal. The NaOH-HF leaching process has been found to be the most effective method of coal de-ashing. The two acid treatment steps (HCl-H{sub 2}SO{sub 4}/HCl-HNO{sub 3}) after caustic leaching are the next most effective methods of coal de-ashing. The removal of mineral matter (including S) from coal is expected to decrease the graphite reactivity and thus the atmospheric pollution (due to the generation of smaller quantities of CO and SO{sub 2} gases).

  7. Thermal, solution and reductive decomposition of Cu-Al layered double hydroxides into oxide products

    SciTech Connect

    Britto, Sylvia; Vishnu Kamath, P.

    2009-05-15

    Cu-Al layered double hydroxides (LDHs) with [Cu]/[Al] ratio 2 adopt a structure with monoclinic symmetry while that with the ratio 0.25 adopt a structure with orthorhombic symmetry. The poor thermodynamic stability of the Cu-Al LDHs is due in part to the low enthalpies of formation of Cu(OH){sub 2} and CuCO{sub 3} and in part to the higher solubility of the LDH. Consequently, the Cu-Al LDH can be decomposed thermally (150 deg. C), hydrothermally (150 deg. C) and reductively (ascorbic acid, ambient temperature) to yield a variety of oxide products. Thermal decomposition at low (400 deg. C) temperature yields an X-ray amorphous residue, which reconstructs back to the LDH on soaking in water or standing in the ambient. Solution decomposition under hydrothermal conditions yields tenorite at 150 deg. C itself. Reductive decomposition yields a composite of Cu{sub 2}O and Al(OH){sub 3}, which on alkali-leaching of the latter, leads to the formation of fine particles of Cu{sub 2}O (<1 {mu}m). - Graphical abstract: SEM image of (a) the Cu{sub 2}O-Al(OH){sub 3} composite obtained on reductive decomposition of CuAl{sub 4}-LDH and (b) Cu{sub 2}O obtained on leaching of Al(OH){sub 3} from (a).

  8. Equilibrium and kinetics of color removal from dye solutions with bentonite and polyaluminum hydroxide.

    PubMed

    Kacha, S; Derriche, Z; Elmaleh, S

    2003-01-01

    Wastewater from the textile industry contains soluble dyes that are toxic and particularly difficult to remove. A promising low-cost treatment, however, is use of polyaluminum hydroxide associated with bentonite. At suitable conditions, this process is able to efficiently remove color from solutions containing mixtures of soluble acid azo dyes and produce easily settleable sludge. The removal mechanism, which is believed to involve adsorption or precipitation and weak pH variations, is not well understood. With the overall reaction being second order, two elementary first-order reactions could be assumed. The equilibrium removal is a decreasing function of the temperature. However, this effect is weak and decreases when the dye concentration increases. At usual values of concentration in textile wastewater, this effect can be neglected. The resulting solid compound is particularly resistant to mechanical stress. Moreover, color was significantly released at pH greater than 8. Sodium ions have no influence on the compound stability, which reinforces the assumption of the involvement of an adsorption process. PMID:12683459

  9. STABILITY OF DOW CORNING Q2-3183A ANTIFOAM IN IRRADIATED HYDROXIDE SOLUTION

    SciTech Connect

    White, T; Crawford, C; Burket, P; Calloway, B

    2009-10-19

    Researchers at the Savannah River National Laboratory (SRNL) examined the stability of Dow Corning Q2-3183A antifoam to radiation and aqueous hydroxide solutions. Initial foam control studies with Hanford tank waste showed the antifoam reduced foaming. The antifoam was further tested using simulated Hanford tank waste spiked with antifoam that was heated and irradiated (2.1 x 10{sup 4} rad/h) at conditions (90 C, 3 M NaOH, 8 h) expected in the processing of radioactive waste through the Waste Treatment and Immobilization Plant (WTP) at Hanford. After irradiation, the concentration of the major polymer components polydimethylsiloxane (PDMS) and polypropylene glycol (PPG) in the antifoam was determined by gel permeation chromatography (GPC). No loss of the major polymer components was observed after 24 h and only 15 wt% loss of PDMS was reported after 48 h. The presence of degradation products were not observed by gas chromatography (GC), gas chromatography mass spectrometry (GCMS) or high performance liquid chromatography mass spectrometry (HPLC-MS). G values were calculated from the GPC analysis and tabulated. The findings indicate the antifoam is stable for 24 h after exposure to gamma radiation, heat, and alkaline simulated waste.

  10. Effect of competing amines on the removal of tetramethylammonium hydroxide from solution using ion exchange.

    PubMed

    Citraningrum, H M; Liu, Jhy-Chern

    2016-01-01

    Tetramethylammonium hydroxide (TMAH, TMA(+)) has been widely used as the photoresist developer in semiconductor and thin film transistor liquid crystal display manufacturing. In this study, TMAH-containing wastewater was treated by ion exchange method. Strong acid cation exchange resin was used. A kinetics study revealed that the ion exchange reaction reached equilibrium within 20 min and it could be described by a pseudo-second-order model. To assess the effects of competing ions, wastewater was spiked with three different amines, namely ethylamine (EA(+)), diethylamine (DEA(+)), and triethylamine (TEA(+)). TMAH uptake decreased when in the presence of amines, and it decreased in the order EA(+) < DEA(+) < TEA(+). It could be attributed to different proton affinity (PA) and the strength of affinity between amine molecules and resin matrix, as found from the ab initio calculation values and Langmuir isotherm parameters. However, the interaction energy between sulphonic acid groups and interfering amines in solution using density functional theory (DFT) calculation resulted in a different trend compared with that of PA. The difference might be caused by stabilization of amines by resin matrix and different molecular structures. PMID:27438252

  11. Influence and hydrolysis kinetics in titanyl sulfate solution from the sodium hydroxide molten salt method

    NASA Astrophysics Data System (ADS)

    Wang, Weijing; Chen, Desheng; Chu, Jinglong; Li, Jie; Xue, Tianyan; Wang, Lina; Wang, Dong; Qi, Tao

    2013-10-01

    Hydrated titanium dioxide (HTD) was precipitated by thermal hydrolysis in purified titanyl sulfate solution (TSS) obtained through the sodium hydroxide molten salt clean method. Various factors including the stirring speed and initial concentrations of TiOSO4, sulfuric acid, and sodium ion were studied. The main influence factors in the hydrolysis process were the initial concentrations of TiOSO4 and sulfuric acid. Contrary to the ferrous ion, the sodium ion improved the ionic activity of Ti4+, but did not decrease the crystal size. The Boltzman growth model (x=A2+(A1-A2)/{1+exp[(t-t0)/dt)]}, which focuses on two main parameters (CTiOSO4 and CH2SO4), fits the hydrolysis process well with R2>0.97. An increase in sulfuric acid concentration negatively affected the hydrolysis rates and the value of A2, while t0 increased. An increase in titanyl sulfate concentration directly reduced the hydrolysis rates and particle size of HTD, contrary to the trend for the value of t0. A simulation software called 1stopt was used to observe the relationship between Z (A1, A2, t0, dt) and a, b (CTiO2 and CH2SO4).

  12. Novel technique for phosphorus recovery from aqueous solutions using amorphous calcium silicate hydrates (A-CSHs).

    PubMed

    Okano, Kenji; Uemoto, Masahide; Kagami, Jumpei; Miura, Keiichi; Aketo, Tsuyoshi; Toda, Masaya; Honda, Kohsuke; Ohtake, Hisao

    2013-05-01

    A novel technique for phosphorus (P) recovery from aqueous solutions was developed using amorphous calcium silicate hydrates (A-CSHs). A-CSHs, which have a high Ca/Si molar ratio of 2.0 or greater, could be synthesized using unlimitedly available, inexpensive materials such as siliceous shale and calcium hydroxide. A-CSHs showed high performance for P recovery from an anaerobic sludge digestion liquor (ASDL) and the synthetic model liquor (s-ASDL) containing 89 mg PO4-P/L. After 20 min mixing, 1.5 g/L A-CSHs could remove approximately 69 and 73% PO4-P from ASDL and s-ASDL, respectively. By contrast, autoclaved lightweight concrete particles, which contained crystalline calcium silicate hydrates as a principal component, removed only 10 and 6% PO4-P from ASDL and s-ASDL, respectively, under the same experimental conditions. When A-CSHs were washed with deionized water to remove free Ca(OH)2, P removability was significantly improved (up to 82%) despite the reduction in the amount of Ca(2+) released. Unlike in the case of Ca(OH)2, no significant carbonate inhibition was observed with P removal by A-CSHs. Moreover, P removed by A-CSHs showed better settleability, filterability, and dewaterability than P precipitated with conventional CaCl2 and Ca(OH)2. The present study demonstrated that A-CSHs have great potential as a novel, beneficial material for P recovery and recycling. PMID:23497975

  13. The effects of calcium hydroxide-treated whole-plant and fractionated corn silage on intake, digestion, and lactation performance in dairy cows.

    PubMed

    Cook, D E; Bender, R W; Shinners, K J; Combs, D K

    2016-07-01

    The objective of this trial was to evaluate, in dairy cattle, the effects of calcium hydroxide treatment of whole-plant corn and a treatment applied to the bottom stalk fraction of the corn plant, achieved by harvesting corn in 2 crop streams. The treatments were calcium hydroxide-treated corn silage (TRTCS), toplage supplemented with calcium hydroxide-treated stalklage (TPL), a positive control of brown midrib corn silage (BMR), and a negative control of conventional whole-plant corn silage (WPCS). The toplage was harvested at a height of 82 cm with 2 of the 6 rows set as ear-snapping to incorporate higher tissues into the stalklage. Stalklage was harvested at 12 cm, and other corn silages were harvested at 27 cm. Sixteen pens, each with 8 Holstein cows averaging 70±25 d in milk and 46±11 kg of milk d(-1), were assigned 4 per treatment in a completely randomized design. The diet was approximately 40% corn silage, 20% alfalfa silage, and 40% concentrate on a dry matter basis. A 2-wk covariate period with conventional corn silage was followed by an 8-wk treatment period in which the 4 corn silage treatments were the only effective difference in diets. Cows fed TPL and TRTCS consumed more (1.9 and 1.4 kg of organic matter d(-1), respectively) than did cows fed WPCS. Milk yield was greater for cows fed BMR, TPL, and TRTCS. Cows fed BMR and TPL produced 2.9 and 2.7 kg d(-1), respectively, more energy-corrected milk (ECM) than cows fed WPCS, and cows fed TRTCS had the greatest ECM production (4.8 kg of ECM d(-1) greater than cows fed WPCS). No differences in body weight or body condition scored were observed. Milk fat concentration was similar among treatments and milk protein concentration was reduced for TRTCS. Starch and neutral detergent fiber digestibility were greater for cows fed TRTCS. PMID:27157570

  14. Comparative Evaluation of Propolis, Metronidazole with Chlorhexidine, Calcium Hydroxide and Curcuma Longa Extract as Intracanal Medicament Against E.faecalis– An Invitro Study

    PubMed Central

    Nair, Rashmi; Asrani, Hemant

    2015-01-01

    Introduction The increase of potential side effects and safety concerns of conventional medicaments have led to the recent popularity of herbal alternative medications. The herbal products are known for its high antimicrobial activity, biocompatibility, anti-inflammatory and antioxidant properties. Aim The purpose of this study was to investigate and compare the effectiveness of Propolis, Metronidazole with Chlorhexidine gel, Curcuma Longa and Calcium Hydroxide for elimination of E.faecalis bacteria in extracted teeth samples. Materials and Methods Ninety extracted single rooted intact teeth were taken for the study. Decoronation, removal of apices and chemomechanical preparation was done for all samples. These sterilized samples were then contaminated with pure culture of E.faecalis under laminar flow. The samples were incubated for a period of 21 days. The infected samples were assigned to 5 groups: Group I- Propolis; Group II- Metronidazole with Chlorhexidine gel; Group III- Calcium hydroxide; Group IV- Curcuma Longa; and control group- Saline. Efficacy of newer intracanal medicaments against E.faecalis were carried out in the samples at the end of 1, 2 & 5 days for each group with the help of colorimeter. Student paired t-test, ANOVA and multiple tukey test were used for statistical analysis. Results The value of optical density was statistically significant in all groups when compared to that of control group. Group I (Propolis) produced better antimicrobial efficacy followed by Chlorhexidine Metronidazole combination, Curcuma Longa and Calcium hydroxide. Conclusion Within the limitations of this study, it can be concluded that Propolis showed better antimicrobial properties against E.faecalis than other medicaments. PMID:26673857

  15. Antibacterial effect of calcium hydroxide combined with chlorhexidine on Enterococcus faecalis: a systematic review and meta-analysis

    PubMed Central

    SAATCHI, Masoud; SHOKRANEH, Ali; NAVAEI, Hooman; MARACY, Mohammad Reza; SHOJAEI, Hasan

    2014-01-01

    Objective Enterococcus faecalis (E. faecalis) is the most frequently isolated strain in failed endodontic therapy cases since it is resistant to calcium hydroxide (CH). Whether a combination of CH and chlorhexidine (CHX) is more effective than CH alone against E. faecalis is a matter of controversy. Thus, the aim of this study was to conduct a systematic review and meta-analysis of the literature. Material and Methods A comprehensive search in PubMed, EMbase, EBSCOhost, The Cochrane Library, SciELO, and BBO databases, Clinical trials registers, Open Grey, and conference proceedings from the earliest available date to February 1, 2013 was carried out and the relevant articles were identified by two independent reviewers. Backward and forward search was performed and then inclusion and exclusion criteria were applied. The included studies were divided into "comparisons" according to the depth of sampling and dressing period of each medicament. Meta-analysis was performed using Stata software 10.0. The level of significance was set at 0.05. Results Eighty-five studies were retrieved from databases and backward/forward searches. Fortyfive studies were considered as relevant (5 in vivo, 18 in vitro, 18 ex vivo, and 4 review articles). Nine studies were included for meta-analysis. Inter-observer agreement (Cohen kappa) was 0.93. The included studies were divided into 21 comparisons for meta-analysis. Chi-square test showed the comparisons were heterogeneous (p<0.001). Random effect model demonstrated no significant difference between CH/CHX mixture and CH alone in their effect on E. faecalis (p=0.115). Conclusions According to the evidence available now, mixing CH with CHX does not significantly increase the antimicrobial activity of CH against E. faecalis. It appears that mixing CH with CHX does not improve its ex vivo antibacterial property as an intracanal medicament against E. faecalis. Further in vivo studies are necessary to confirm and correlate the findings of

  16. The electrokinetic behavior of calcium oxalate monohydrate in macromolecular solutions

    NASA Technical Reports Server (NTRS)

    Curreri, P. A.; Onoda, G. Y., Jr.; Finlayson, B.

    1988-01-01

    Electrophoretic mobilities were measured for calcium oxalate monohydrate (COM) in solutions containing macromolecules. Two mucopolysaccharides (sodium heparin and chrondroitin sulfate) and two proteins (positively charged lysozyme and negatively charged bovine serum albumin) were studied as adsorbates. The effects of pH, calcium oxalate surface charge (varied by calcium or oxalate ion activity), and citrate concentration were investigated. All four macromolecules showed evidence for chemical adsorption. The macromolecule concentrations needed for reversing the surface charge indicated that the mucopopolysacchrides have greater affinity for the COM surface than the proteins. The amount of proteins that can chemically adsorb appears to be limited to approximately one monomolecular layer. When the surface charge is high, an insufficient number of proteins can chemically adsorb to neutralize or reverse the surface charge. The remaining surface charge is balanced by proteins held near the surface by longer range electrostatic forces only. Citrate ions at high concentrations appear to compete effectively with the negative protein for surface sites but show no evidence for competing with the positively charged protein.

  17. Calcium hydroxide poisoning

    MedlinePlus

    Wax PM, Yarema M. Corrosives. In: Shannon MW, Borron SW, Burns MJ, eds. Haddad and Winchester's Clinical ... ed. Philadelphia, PA: Elsevier Saunders; 2007:chap 98. Wax PM, Young A. Caustics. In: Marx JA, Hockberger ...

  18. Aluminum Hydroxide and Magnesium Hydroxide

    MedlinePlus

    Aluminum Hydroxide, Magnesium Hydroxide are antacids used together to relieve heartburn, acid indigestion, and upset stomach. They ... They combine with stomach acid and neutralize it. Aluminum Hydroxide, Magnesium Hydroxide are available without a prescription. ...

  19. Comparative efficacy of photo-activated disinfection and calcium hydroxide for disinfection of remaining carious dentin in deep cavities: a clinical study

    PubMed Central

    Sharma, Sidhartha; Shah, Naseem

    2014-01-01

    Objectives To comparatively evaluate the efficacy of photo-activated disinfection (PAD), calcium hydroxide (CH) and their combination on the treatment outcome of indirect pulp treatment (IPT). Materials and Methods Institutional ethical clearance and informed consent of the patients were taken. The study was also registered with clinical registry of India. Sixty permanent molars exhibiting deep occlusal carious lesion in patients with the age range of 18 - 22 yr were included. Clinical and radiographic evaluation and set inclusion and exclusion criteria's were followed. Gross caries excavation was accomplished. In group I (n = 20) PAD was applied for sixty seconds. In group II (n = 20), CH was applied to the remaining carious dentin, while in group III (n = 20), PAD application was followed by CH placement. The teeth were permanently restored. They were clinically and radiographically followed-up at 45 day, 6 mon and 12 mon. Relative density of the remaining affected dentin was measured by 'Radiovisiography (RVG) densitometric' analysis. Results Successful outcome with an increase in radiographic grey values were observed in all three groups. However, on inter-group comparison, this change was not significant (p > 0.05). Conclusions PAD and CH both have equal disinfection efficacy in the treatment of deep carious dentin. PAD alone is as effective for treatment of deep carious lesion as calcium hydroxide and hence can be used as an alternative to CH. They can be used independently in IPT, since combining both does not offer any additional therapeutic benefits. PMID:25110643

  20. Analysis of the healing process in delayed tooth replantation after root canal filling with calcium hydroxide, Sealapex and Endofill: a microscopic study in rats.

    PubMed

    Negri, Márcia Regina; Panzarini, Sônia Regina; Poi, Wilson Roberto; Sonoda, Celso Koogi; Gulinelli, Jéssica Lemos; Saito, Célia Tomiko Matida Hamata

    2008-12-01

    The major concern in the therapeutics of tooth replantation refers to the occurrence of root resorption and different approaches have been proposed to prevent or treat these complications. The purpose of this study was to evaluate tissue response to delayed replantation of anterior rat teeth treated endodontically using calcium hydroxide, Sealapex, and Endofill without the placement of gutta-percha cones. Thirty rats had their right upper incisor extracted and maintained in dry storage for 60 min. After removal of the dental papilla, enamel organ, pulp tissue, and periodontal ligament remnants, the teeth were immersed in 2% sodium fluoride phosphate acidulated, pH 5.5, for 10 min. The root canals were dried with absorbent paper points and the teeth were assigned to three groups (n = 10) according to the filling material. Group I - calcium hydroxide and propyleneglycol paste, Group II - Sealapex, and Group III - Endofill. The sockets were irrigated with saline and the teeth were replanted. Replacement resorption, inflammatory resorption and ankylosis were observed in all groups. Although the occurrence of inflammatory resorption was less frequent in Group I, there were no statistically significant differences among the groups. It may be concluded that compared to the paste, filling the root canals with Sealapex and Endofill sealers without the placement of gutta-percha cones did not provide better results. PMID:19021658

  1. IGA of alloy 600 in high-temperature solutions of sodium hydroxide contaminated with carbonate. Final report. [PWR

    SciTech Connect

    Roberge, R.; Bandy, R.; van Rooyen, D.

    1983-05-01

    Alloy 600 was tested in sodium hydroxide contaminated with sodium carbonate at 300/sup 0/C and 315/sup 0/C to examine its resistance to intergranular attack (IGA) under controlled cathodic and anodic potentials. Specimens of alloy 600 were studied as C-rings under constant deflection, wires under constant load and wires without any applied tensile stress. The material was mainly used in its mill annealed condition, although some specimens were studied as solution annealed and solution annealed plus sensitized. Unlike the last two metallurgical states, the mill annealed alloy 600 material was rather sensitive to stress corrosion cracking (SCC) in a range of anodic potentials.

  2. Chemical comminution of coal in pressurized binary system of carbon-dioxide and sodium-hydroxide solution

    SciTech Connect

    Mamaghani, A.H.

    1988-01-01

    Chemical comminution of coal involves introduction of reactive chemical agent into a coal seam converting the monolithic coal into a particulate slurry of coal particles. A pressurized binary system of carbon dioxide and sodium hydroxide solution and a pressurized system of carbon dioxide and water were used as the chemical reagents and their comminution ability were studied under different conditions of reactor pressure, reagent concentration, reaction time, and reactor temperature. These variables showed significant effects on the fragmentation rates. It was shown that comminution rates increased with a rise in reactor pressure and temperature. The maximum comminution rates were obtained around 7 molar sodium hydroxide concentration. The activation energy of the chemical comminution was calculated to be around 4650 calories per gram mole. The comminution rates ranged from 0.5 to 355.0 cm{sup 2}/hr-g. The Iowa coal proved to react better with these systems than Ohio coal.

  3. Depolarization-induced contractile activity of smooth muscle in calcium-free solution.

    PubMed

    Mangel, A W; Nelson, D O; Rabovsky, J L; Prosser, C L; Connor, J A

    1982-01-01

    In calcium-free solution, strips of cat intestinal muscle developed slow, rhythmic electrical potential changes that triggered contractions. Some strips failed to develop spontaneous electrical activity in calcium-free solution but responded with contractions to depolarization by direct electrical stimulation or by treatment with barium chloride, potassium chloride, or acetylcholine. Similar results were obtained with segments of cat stomach, colon, esophagus, bladder, uterus, and vena cava, as well as with rabbit vena cava. In calcium-free saline, rat small intestinal muscle showed fast electrical activity with accompanying development of a tetanuslike contraction. After 60 min in calcium-free solution, cat small intestinal muscle retained 17.7% of its original concentration of calcium. It is concluded that in some smooth muscles, depolarization-triggered release of intracellular calcium does not require an associated influx of calcium. PMID:7058877

  4. Theoretical investigation on the mechanism and dynamics of oxo exchange of neptunyl(VI) hydroxide in aqueous solution.

    PubMed

    Yang, Xia; Chai, Zhifang; Wang, Dongqi

    2015-03-21

    Four types of reaction mechanisms for the oxo ligand exchange of monomeric and dimeric neptunyl(VI) hydroxide in aqueous solution were explored computationally using density functional theory (DFT) and ab initio classical molecular dynamics. The obtained results were compared with previous studies on the oxo exchange of uranyl hydroxide, as well as with experiments. It is found that the stable T-shaped [NpO3(OH)3](3-) intermediate is a key species for oxo exchange in the proton transfer in mononuclear Path I and binuclear Path IV, similar to the case of uranyl(VI) hydroxide. Path I is thought to be the preferred oxo exchange mechanism for neptunyl(VI) hydroxide in our calculations, due to the lower activation energy (22.7 and 13.1 kcal mol(-1) for ΔG(‡) and ΔH(‡), respectively) of the overall reaction. Path II via a cis-neptunyl structure assisted by a water molecule might be a competitive channel against Path I with a mononuclear mechanism, owing to a rapid dynamical process occurring in Path II. In Path IV with the binuclear mechanism, oxo exchange is accomplished via the interaction between [NpO2(OH)4](2-) and T-shaped [NpO3(OH)3](3-) with a low activation energy for the rate-determining step, however, the overall energy required to fulfill the reaction is slightly higher than that in mononuclear Path I, suggesting a possible binuclear process in the higher energy region. The chemical bonding evolution along the reaction pathways was discussed by using topological methodologies of the electron localization function (ELF). PMID:25706188

  5. Autopsy results of a case of ingestion of sodium hydroxide solution.

    PubMed

    Emoto, Yuko; Yoshizawa, Katsuhiko; Shikata, Nobuaki; Tsubura, Airo; Nagasaki, Yasushi

    2016-01-01

    Sodium hydroxide is a strongly corrosive alkali. We describe herein a case of suicide by ingestion of sodium hydroxide. A man in his 80s was found dead with a mug and a bottle of caustic soda. Macroscopically, liquefaction and/or disappearance of esophagus, trachea and lung tissue and a grayish discoloration of the mucosa of the stomach were seen along with blackish brown coloration of the skin, mouth, and oral cavity. The contents of the gastrointestinal tract showed a pH level of 7-8 on pH indicator strips. Histopathologically, liquefactive necrosis of remnant lung tissue and the stomach were seen. As biological reactions such as vasodilatation and inflammation were not detected in these organs, only a short number of hours must have passed between ingestion and death. This human case provides valuable information concerning the direct irritation induced by systemic exposure to corrosive substances. PMID:26989301

  6. Synthesis and characterization of cadmium-calcium hydroxyapatite solid solutions

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Zhu, Yi-nian; Dai, Liu-qin

    2014-06-01

    A series of cadmium-calcium hydroxyapatite solid solutions was prepared by an aqueous precipitation method. By various means, the characterizations confirmed the formation of continuous solid solutions over all ranges of Cd/(Cd+Ca) atomic ratio. In the results, both lattice parameters a and c display slight deviations from Vegard's rule when the Cd/(Cd+Ca) atomic ratio is greater than 0.6. The particles change from smaller acicular to larger hexagonal columnar crystals as the Cd/(Cd+Ca) atomic ratio increases from 0-0.60 to 0.60-1.00. The area of the phosphate peak for symmetric P-O stretching decreases with the increase in Cd/(Cd+Ca) atomic ratio, and the peak disappears when the Cd/(Cd+Ca) atomic ratio is greater than 0.6; the two phosphate peaks of P-O stretching gradually merge together for the Cd/(Cd+Ca) atomic ratio near 0.60. These variations can be explained by a slight tendency of larger Cd ions to occupy M(2) sites and smaller Ca ions to prefer M(1) sites in the structure.

  7. Antimicrobial effect of calcium hydroxide as an intracanal medicament in root canal treatment: a literature review - Part II. in vivo studies

    PubMed Central

    2015-01-01

    The first part of this study reviewed the characteristics of calcium hydroxide (Ca(OH)2) and summarized the results of in vitro studies related to its antimicrobial effects. The second part of this review covers in vivo studies including human clinical studies and animal studies. The use of Ca(OH)2 as an intracanal medicament represented better histological results in animal studies. However, human clinical studies showed limited antimicrobial effects that microorganisms were reduced but not eliminated through the treatment, and that some species had resistance to Ca(OH)2. Most of clinical outcome studies supported that there is no improvement in healing of periapical lesions when Ca(OH)2 was applied between appointments. Further studies are required for the antimicrobial effects of Ca(OH)2, and search for the ideal material and technique to completely clean infected root canals should be continued. PMID:25984470

  8. A prospective clinical trial on the influence of a triamcinolone/demeclocycline and a calcium hydroxide based temporary cement on pain perception

    PubMed Central

    2012-01-01

    Introduction The aim of this clinical trial was to compare the degree of short term post-operative irritation after application of a triamcinolone/demeclocycyline based or a calcium hydroxide based provisional cement. Methods A total of 109 patients (55 female and 54 male; mean age: 51 ± 14 years) with primary or secondary dentinal caries were randomly assigned to the two treatment groups of this biomedical clinical trial (phase III). Selection criteria were good systemic health and treated teeth, which were vital and showed no symptoms of pulpitis. Up to three teeth were prepared for indirect metallic restorations, and the provisional restorations were cemented with a triamcinolone/demeclocycyline (Ledermix) or a calcium hydroxide (Provicol) based material. The intensity of post-operative pain experienced was documented according to the VAS (4, 12, 20, 24, and 82 h) and compared to VAS baseline. Results A total of 159 teeth were treated (Ledermix: 83 teeth, Provicol: 76 teeth). The minor irritation of the teeth, experienced prior to treatment, was similar in both groups; however, 4 h after treatment this value was significantly higher in the Provicol group than in the Ledermix group (p < 0.005, t-test). After 12 h, the difference was no longer significant. The number of patients taking analgesics for post-treatment pain was higher in the Provicol group (n = 11/53) than in the Ledermix group (n = 3/56). Conclusions The patients had no long term post-operative pain experience in both groups. However, within the first hours after cementation the sensation of pain was considerably higher in the Provicol group than in the Ledermix group. PMID:22414157

  9. Calcium Binding to Amino Acids and Small Glycine Peptides in Aqueous Solution: Toward Peptide Design for Better Calcium Bioavailability.

    PubMed

    Tang, Ning; Skibsted, Leif H

    2016-06-01

    Deprotonation of amino acids as occurs during transfer from stomach to intestines during food digestion was found by comparison of complex formation constants as determined electrochemically for increasing pH to increase calcium binding (i) by a factor of around 6 for the neutral amino acids, (ii) by a factor of around 4 for anions of the acidic amino acids aspartic and glutamic acid, and (iii) by a factor of around 5.5 for basic amino acids. Optimized structures of the 1:1 complexes and ΔHbinding for calcium binding as calculated by density functional theory (DFT) confirmed in all complexes a stronger calcium binding and shorter calcium-oxygen bond length in the deprotonated form. In addition, the stronger calcium binding was also accompanied by a binding site shift from carboxylate binding to chelation by α-amino group and carboxylate oxygen for leucine, aspartate, glutamate, alanine, and asparagine. For binary amino acid mixtures, the calcium-binding constant was close to the predicted geometric mean of the individual amino acid binding constants indicating separate binding of calcium to two amino acids when present together in solution. At high pH, corresponding to conditions for calcium absorption, the binding affinity increased in the order Lys < Arg < Cys < Gln < Gly ∼ Ala < Asn < His < Leu < Glu< Asp. In a series of glycine peptides, calcium-binding affinity was found to increase in the order Gly-Leu ∼ Gly-Gly < Ala-Gly < Gly-His ∼ Gly-Lys-Gly < Glu-Cys-Gly < Gly-Glu, an ordering confirmed by DFT calculations for the dipeptides and which also accounted for large synergistic effects in calcium binding for up to 6 kJ/mol when compared to the corresponding amino acid mixtures. PMID:27159329

  10. Recovery of acids and sodium hydroxide from solutions of sodium sulfate and sodium chloride with the use of bipolar membranes

    SciTech Connect

    Bobrinskaya, G.A.; Pavlova, T.V.; Shatalov, A.Ya.

    1985-09-01

    The authors examined the kinetic laws governing the electrodialysis recovery of hydrochloric acid and sulfuric acid, as well as sodium hydroxide, from 1M sodium chloride and 0.5 M sodium sulfate solutions and from a mixture of these salts with the use of the MB-1, MB-2, and MB-3 bipolar membranes. Kinetic plots of the current density and the concentration of the acid and the base in the chambers next to the bipolar membranes during the electrodialysis treatment of 1M sodium chloride, 0.5 M sodium sulfate, and solutions are presented. It was established that it is better to use the MB-3 membrane for the electrodialysis conversion of sodium chloride and sodium sulfate into acids and sodium hydroxide owing to the high rate and current efficiency and low expenditure of electrical energy and degree of contamination of the products obtained by the salts. It was also established that the resistance of the MB-1 and MB-2 bipolar membranes is almost an order of magnitude higher than that of the MB-3 membrane.

  11. Forty-Five Degree Micromirror Fabrication Using Silicon Anisotropic Etching with Surfactant-Added Tetramethylammonium Hydroxide Solution

    NASA Astrophysics Data System (ADS)

    Yagyu, Hiroyuki; Yamaji, Tadahiro; Nishimura, Makoto; Sato, Kazuo

    2010-09-01

    Flat and smooth 45° micromirrors were successfully fabricated on a 4-in. silicon wafer by means of wet anisotropic etching at the industrially practical temperature of 80 °C using tetramethylammonium hydroxide (TMAH) solution with added NCW-1002, a nonionic surfactant with little environmental load. The effects of the TMAH concentration and the amount of NCW-1002 added were extensively investigated, and it was found that a high TMAH concentration (25 wt %) and a very low amount of NCW-1002, approximately 10 vol ppm, are the optimum conditions to fabricate optically smooth and geometrically flat micromirrors. The mechanism underlying the effects of the concentration of the surfactant is discussed in relation to the clouding point of the surfactant-added TMAH solution.

  12. A balanced salt solution that prevents agglomeration of nano iron oxo-hydroxides in serum-free cellular assays

    NASA Astrophysics Data System (ADS)

    Pereira, Dora I. A.; Lederer, Bianca; Powell, Jonathan J.

    2015-01-01

    Nano iron oxo-hydroxides have numerous and increasing applications in biology and medicine. Assessment of their uptake and toxicity often requires cell culture but maintaining iron oxides uniformly nano-dispersed in such conditions can be challenging. We describe a balanced salt solution (BSS) compatible with cellular assays for use in such investigations. We determined hydrodynamic particle size and dispersibility of nano iron in BSS. The BSS, containing 130 mM NaCl, 10 mM KCl, 1 mM MgSO4, 5 mM glucose and 1.8 mM CaCl2 in 10 mM PIPES buffer (pH 7.4), was capable of maintaining nanoparticulate tartrate-modified Fe(III) oxo-hydroxide (i.e. nano Fe) mono-disperse (≥95% nanoparticulate) with a mean hydrodynamic particle diameter of 6.1 ± 0.3 nm. This size was similar to the native form of the nano Fe material (i.e. as synthesized) with a mean hydrodynamic particle diameter of 4.3 ± 0.1 nm in water. Furthermore, we show that BSS also adequately maintains nano Fe dispersion when supplemented with inhibitors of particle uptake or lysosomal acidification, namely chloropromazine and monensin, and when used at pHs 6.5 or 5.8. In conclusion, we provide a method for nanodispersion of iron oxo-hydroxides that is suitable for short term (1-3 h) cellular exposure investigations.

  13. Nanostructuring of nickel hydroxide via a template solution approach for efficient electrochemical devices.

    PubMed

    Guo, Li; Ren, Yi; Liu, Junyi; Chiam, Sing Yang; Chim, Wai Kin

    2014-07-01

    Nanostructuring is a key approach in enhancing the performance of electrochemical devices. In this work, nanostructuring is achieved by the electrodeposition of nickel hydroxide nanowire arrays, with both open-ended and close-ended structures, through anodized aluminium oxide (AAO) templates that are directly fabricated on indium tin oxide/glass substrates. The open-ended and close-ended nanostructures are compared together with identically fabricated thin films to show the effects of nanostructuring. Open-ended nanowire arrays demonstrated the best electrochemical activity with superior transmittance modulation and faster activation, while the thin film showed the worst performance. In comparing with the close-ended structures, enhanced performance is observed for the open-ended structures despite the use of less material for the latter. This demonstrates that in designing nanostructures or porous materials, it is important for the porosity to have both interconnectivity and exposure to the electrolyte in electrochemical reactions. PMID:24634166

  14. First evidence on phloem transport of nanoscale calcium oxide in groundnut using solution culture technique

    NASA Astrophysics Data System (ADS)

    Deepa, Manchala; Sudhakar, Palagiri; Nagamadhuri, Kandula Venkata; Balakrishna Reddy, Kota; Giridhara Krishna, Thimmavajjula; Prasad, Tollamadugu Naga Venkata Krishna Vara

    2015-06-01

    Nanoscale materials, whose size typically falls below 100 nm, exhibit novel chemical, physical and biological properties which are different from their bulk counterparts. In the present investigation, we demonstrated that nanoscale calcium oxide particles (n-CaO) could transport through phloem tissue of groundnut unlike the corresponding bulk materials. n-CaO particles are prepared using sol-gel method. The size of the as prepared n-CaO measured (69.9 nm) using transmission electron microscopic technique (TEM). Results of the hydroponics experiment using solution culture technique revealed that foliar application of n-CaO at different concentrations (10, 50, 100, 500, 1,000 ppm) on groundnut plants confirmed the entry of calcium into leaves and stems through phloem compared to bulk source of calcium sprayed (CaO and CaNO3). After spraying of n-CaO, calcium content in roots, shoots and leaves significantly increased. Based on visual scoring of calcium deficiency correction and calcium content in plant parts, we may establish the fact that nanoscale calcium oxide particles (size 69.9 nm) could move through phloem tissue in groundnut. This is the first report on phloem transport of nanoscale calcium oxide particles in plants and this result points to the use of nanoscale calcium oxide particles as calcium source to the plants through foliar application, agricultural crops in particular, as bulk calcium application through foliar nutrition is restricted due to its non-mobility in phloem.

  15. Comparisons of kinetics, thermodynamics and regeneration of tetramethylammonium hydroxide adsorption in aqueous solution with graphene oxide, zeolite and activated carbon

    NASA Astrophysics Data System (ADS)

    Chang, Shenteng; Lu, Chungsying; Lin, Kun-Yi Andrew

    2015-01-01

    Graphene oxide (GO), sodium Y-type zeolite (NaY) and granular activated carbon (GAC) are selected as adsorbents to study their kinetics, thermodynamics and regeneration of tetramethylammonium hydroxide (TMAH) adsorption from water. The adsorption kinetics follows the pseudo-second-order rate law while the adsorption thermodynamics shows an exothermic reaction with GO and GAC but displays an endothermic reaction with NaY. The adsorbed TMAH can be readily desorbed from the surface of GO and NaY by 0.05 M NaCl solution. A comparative study on the cyclic TMAH adsorption with GO, NaY and GAC is also conducted and the results reveal that GO exhibits the greatest TMAH adsorption capacity as well as superior reversibility of TMAH adsorption over 10 cycles of adsorption and desorption process. These features indicate that GO is a promising and efficient adsorbent for TMAH removal in wastewater treatment.

  16. Magnesium Hydroxide

    MedlinePlus

    Magnesium hydroxide is used on a short-term basis to treat constipation.This medication is sometimes prescribed ... Magnesium hydroxide come as a tablet and liquid to take by mouth. It usually is taken as ...

  17. Aluminum Hydroxide

    MedlinePlus

    Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

  18. Chemiluminescence flow biosensor for glucose using Mg-Al carbonate layered double hydroxides as catalysts and buffer solutions.

    PubMed

    Wang, Zhihua; Liu, Fang; Lu, Chao

    2012-01-01

    In this work, serving as supports in immobilizing luminol reagent, catalysts of luminol chemiluminescence (CL), and buffer solutions for the CL reaction, Mg-Al-CO(3) layered double hydroxides (LDHs) were found to trigger luminol CL in weak acid solutions (pH 5.8). The silica sol-gel with glucose oxidase and horseradish peroxidase was immobilized in the first half of the inside surface of a clear quartz tube, and luminol-hybrid Mg-Al-CO(3) LDHs were packed in the second half. Therefore, a novel CL flow-through biosensor for glucose was constructed in weak acid solutions. The CL intensity was linear with glucose concentration in the range of 0.005-1.0mM, and the detection limit for glucose (S/N=3) was 0.1 μM. The proposed biosensor exhibited excellent stability, high reproducibility and high selectivity for the determination of glucose and has been successfully applied to determine glucose in human plasma samples with satisfactory results. The success of this work has broken the bottleneck of the pH incompatibility between luminol CL and enzyme activity. PMID:22770831

  19. Low temperature solution deposition of calcium phosphate coatings for orthopedic implants

    SciTech Connect

    Campbell, A.A.; Graff, G.L.

    1994-04-01

    Calcium phosphate coatings were grown from aqueous solution onto a derivatized self-assmebled monolayer (SAM) which was covalently bound to a titanium metal substrate. The SAM molecules provided an idea connection between the metal surface and the calcium phosphate coating. The trichlorosilane terminus of the SAM molecule insured covalent attachment to the surface, while the functionalized ``tail`` induced heterogeneous nucleation of the calcium phosphate coating from supersaturated solutions. This low temperature process allowed for uniform coatings to be produced onto complex-shaped and/or microporous surfaces and provided better control of phase purity.

  20. Calcium

    MedlinePlus

    ... of calcium dietary supplements are carbonate and citrate. Calcium carbonate is inexpensive, but is absorbed best when taken ... antacid products, such as Tums® and Rolaids®, contain calcium carbonate. Each pill or chew provides 200–400 mg ...

  1. Pulp response to high fluoride releasing glass ionomer, silver diamine fluoride, and calcium hydroxide used for indirect pulp treatment: An in-vivo comparative study

    PubMed Central

    Korwar, Atish; Sharma, Sidhartha; Logani, Ajay; Shah, Naseem

    2015-01-01

    Aims and Objectives: The study aims at determining pulp response of two high fluoride releasing materials silver diamine fluoride (SDF) and Type VII glass ionomer cement (GIC) when used as indirect pulp treatment (IPT) materials. Materials and Methods: Deep Class V cavities were made on four first premolars indicated for extraction for orthodontic reasons. SDF, Type VII GIC, and calcium hydroxide base are given in three premolars, and one is kept control. Premolars were extracted 6 weeks after the procedure and subjected to histopathological examination to determine the pulp response. The results were analyzed using Chi-square test. Results: No inflammatory changes were observed in any of the groups. Significantly more number of specimens in SDF and Type VII GIC groups showed tertiary dentin deposition (TDD) when compared to control group. No significant difference was seen in TDD when intergroup comparison was made. Odontoblasts were seen as short cuboidal cells with dense basophilic nucleus in SDF and Type VII GIC group. Conclusion: The study demonstrated TDD inducing ability of SDF and Type VII GIC and also established the biocompatibility when used as IPT materials. PMID:26321822

  2. Hydrothermal treatment of naturally contaminated maize in the presence of sodium metabisulfite, methylamine and calcium hydroxide; effects on the concentration of zearalenone and deoxynivalenol.

    PubMed

    Rempe, Inga; Kersten, Susanne; Valenta, Hana; Dänicke, Sven

    2013-08-01

    Fusarium toxin-contaminated ground maize was hydrothermally treated in the presence of different combinations of chemicals in order to simultaneously reduce zearalenone (ZEA) and deoxynivalenol (DON) concentrations. Treatments were carried out in a laboratory conditioner at 80 °C and 17 % moisture. Six different treatments were performed, consisting of 3 doses of methylamine (MMA; 2.5, 5 and 10 g/kg maize) at a constant dose of 5 g sodium metabisulfite (SBS)/kg, either with or without the addition of 20 g calcium hydroxide (Ca(OH)2)/kg. The used maize was contaminated with approximately 45.99 mg DON/kg and 3.46 mg ZEA/kg. Without the addition of Ca(OH)2, DON reductions reached approximately 82% after 1-min treatment and the toxin disappeared nearly completely after 10 min when 2.5 or 5 g MMA were applied. ZEA concentrations were only marginally affected. In the presence of Ca(OH)2, reductions in DON concentrations were lower, but were enhanced by increasing doses of MMA. ZEA concentrations were reduced by 72, 85 and 95% within the first 5 min of the treatment at MMA dosages of 2.5, 5 and 10 g/kg maize, respectively. The application of SBS in combination with a strong alkaline during hydrothermal treatment seems to be a promising approach to simultaneously decontaminate even high amounts of DON and ZEA in ground maize and may contribute to reduce the toxin load of diets. PMID:23536360

  3. Dentinal tubule disinfection with 2% chlorhexidine, garlic extract, and calcium hydroxide against Enterococcus faecalis by using real-time polymerase chain reaction: In vitro study

    PubMed Central

    Eswar, Kandaswamy; Venkateshbabu, Nagendrababu; Rajeswari, Kalaiselvam; Kandaswamy, Deivanayagam

    2013-01-01

    Aim: To compare the efficacy of garlic extract with 2% chlorhexidine (CHX) and calcium hydroxide Ca(OH)2 in disinfection of dentinal tubules contaminated with Enterococcus faecalis by using real-time polymerase chain reaction (PCR). Materials and Methods: Agar diffusion test was done to evaluate the minimum inhibitory concentration of garlic extract against E. faecalis. Forty human extracted mandibular premolar teeth were selected for this study, access cavity was prepared and cleaning and shaping was done. Middle third of the root was cut using a rotary diamond disc. The teeth specimens were inoculated with E. faecalis for 21 days. Specimens were divided into four groups---Group 1: 2% CHX, Group 2: Garlic extract, Group 3: Ca(OH)2, and Group 4: Saline (negative control). The intracanal medicaments were packed inside the tooth specimens and incubated for 5 days. The dentinal chips were collected at 400 μm depth using a Gates-Glidden drill, following which DNA isolation was done. The specimens were analyzed using real-time PCR. The results were then statistically analyzed using one-way analysis of variance, followed by post hoc Tukey's honestly significant difference (HSD) multiple comparison of means. Results: Threshold cycle (Ct) values of 2% CHX was found to be 32.4, garlic extract to be 27.5, and Ca(OH)2 to be 25.6. Conclusion: A total of 2% CHX showed the maximum efficacy against E. faecalis, followed by garlic extract and Ca(OH)2. PMID:23833449

  4. Influence of porosity and relative humidity on consolidation of dolostone with calcium hydroxide nanoparticles: Effectiveness assessment with non-destructive techniques

    SciTech Connect

    Lopez-Arce, P.; Gomez-Villalba, L.S.; Pinho, L.; Fernandez-Valle, M.E.; Alvarez de Buergo, M.; Fort, R.

    2010-02-15

    Slaked lime (Ca(OH){sub 2}) nanoparticles were exposed at 33% and 75% relative humidity (RH) to consolidate dolostone samples used in historical buildings. Non-destructive techniques (NDT) were applied to determine the chemical, morphological, physical and hydric properties of the stone samples, before and after 20 days treatment. Morphological and mineralogical characterisation of the nanoparticles was performed. 75% RH favors the consolidation process studied under Environmental Scanning Electron Microscopy (ESEM-EDS), spectrophotometry, capillarity, water absorption under vacuum, ultrasound velocity, Nuclear Magnetic Resonance (imaging and relaxometry) and Optical Surface Roughness analyses. At 75% RH the nanoparticles fill the pores and inter-crystalline dolomite grain contacts but do not favor calcite re-crystallization as it occurs at 33% RH. The ESEM, XRD and TEM analyses under 75% RH reveal the fast transformation of portlandite (Ca(OH){sub 2}) into vaterite (CaCO{sub 3}), monohydrocalcite (CaCO{sub 3} . H{sub 2}O) and calcite (CaCO{sub 3}), and eventually the physical and hydric properties of the stones significantly improve. New insights are provided for the assessment of consolidation effectiveness of porous carbonate stones with calcium hydroxide nanoparticles under optimum RH conditions combining several NDT.

  5. Cd immobilization in a contaminated rice paddy by inorganic stabilizers of calcium hydroxide and silicon slag and by organic stabilizer of biochar.

    PubMed

    Bian, Rongjun; Li, Lianqing; Bao, Dandan; Zheng, Jinwei; Zhang, Xuhui; Zheng, Jufeng; Liu, Xiaoyu; Cheng, Kun; Pan, Genxing

    2016-05-01

    A field experiment was conducted in a Cd-contaminated rice paddy field to evaluate the effect of inorganic and organic metal stabilizers on Cd mobility and rice uptake. A dose of inorganic stabilizer of calcium hydroxide (CH), silicon slag (SS), and wheat straw biochar (BC) was amended respectively to topsoil before rice transplanting. Rice production was managed with the same water regime and fertilization practices consistently between treatments including a control without amendment. Samples of topsoil and rice plant were collected at rice harvest to analyze the Cd mobility and uptake by rice. Without affecting rice grain yield, the stabilizers significantly decreased CaCl2-extractable Cd in a range of 44 to 75 % compared to the control, corresponding to soil pH changes under the different treatments. Accordingly, Cd concentrations both in rice tissue and in rice grain were very significantly decreased under these treatments. The decrease in rice Cd uptake was correlated to the decrease in extractable Cd, which was again correlated to soil pH change under the different treatments, indicating a prevalent role of liming effect by the amendments. While applied at a large amount in a single year, organic stabilizer of BC decreased Cd extractability by up to 43 % and Cd rice uptake by up to 61 %, being the most effective on Cd immobilization. However, the long-term effect on soil health and potential tradeoff effects with different stabilizers deserve further field monitoring studies. PMID:26865487

  6. The enhancement effect of pre-reduction using zero-valent iron on the solidification of chromite ore processing residue by blast furnace slag and calcium hydroxide.

    PubMed

    Li, Jinchunzi; Chen, Zhonglin; Shen, Jimin; Wang, Binyuan; Fan, Leitao

    2015-09-01

    A bench scale study was performed to assess the effectiveness of the solidification of chromite ore processing residue (COPR) by blast furnace slag and calcium hydroxide, and investigate the enhancement effect of pre-reduction using zero-valent iron (ZVI) on the solidification treatment. The degree of Cr immobilization was evaluated using the Toxicity Characteristic Leaching Procedure (TCLP) as well as the solid waste-extraction procedure for leaching toxicity-sulfuric acid & nitric acid method (Chinese standard HJ/T299-2007). Strength tests and semi-dynamic leaching tests were implemented to investigate the potential for reusing the final treatment product as a readily available construction material. The experimental results showed that the performance of pre-reduction/solidification (S/S) was superior to that of solidification alone. After pre-reduction, all of the S/S treated COPR samples met the TCLP limit for total Cr (5 mg L(-1)), whereas the samples with a COPR content below 40% met the pollution control limit of bricks and building block products (Chinese standard HJ/T 301-2007) produced with COPR for total Cr (0.3 mg L(-1)). At the same time, all of the S/S treated specimens tested were suitable for utilization at certain levels. PMID:25929874

  7. Clinical and radiographic assessment of mineral trioxide aggregate and calcium hydroxide as apexification agents in traumatized young permanent anterior teeth: A comparative study

    PubMed Central

    Damle, S. G.; Bhattal, Hiteshwar; Damle, Dhanashree; Dhindsa, Abhishek; Loomba, Ashish; Singla, Sumit

    2016-01-01

    Background: To evaluate and compare the efficacy of mineral trioxide aggregate (MTA) and traditionally used calcium hydroxide (Ca(OH)2) in inducing root end formation of immature roots of traumatized young permanent anterior teeth. Materials and Methods: The study was carried out on 22 nonvital, immature permanent maxillary incisors. Samples were allotted into two groups - Group I MTA and Group II Ca(OH)2 Success rate was determined based upon the time duration required for apical barrier formation. The canals were obturated using gutta-percha points in MTA group, after 24 h, whereas in Ca(OH)2 group, obturation was carried out after radiographic confirmation of the apical barrier. The clinical and radiographic evaluation was carried out at a follow-up periods of 3, 6, and 9 months and statistical analysis was carried out by SPSS version 15.0 statistical analysis software (Chi-square test and fisher exact test). Results: In MTA Group, barrier formation was observed in 90.90% of the patients after 9 months whereas in Ca(OH)2 Group, the same was observed in 81.81%. The mean time required for barrier formation in MTA group was 4.90 months and 5.33 months in Ca(OH)2 group. Conclusion: MTA and Ca(OH)2, as medicaments for apexification, were comparable in terms of the evaluation parameters. However, MTA was beneficial in terms of immediate obturation of immature roots with wide open apices. PMID:27274351

  8. Oriented single crystalline TiO 2 nano-pillar arrays directly grown on titanium substrate in tetramethylammonium hydroxide solution

    NASA Astrophysics Data System (ADS)

    Dong, Xiang; Tao, Jie; Li, Yingying; Zhu, Hong

    2010-02-01

    Oriented single crystalline titanium dioxide (TiO 2) nano-pillar arrays were directly synthesized on the Ti plate in tetramethylammonium hydroxide (TMAOH) solution by one-pot hydrothermal method. The samples were characterized respectively by means of field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). Results showed that the TiO 2 nano-pillar with a tetrahydral bipyramidal tip grew vertically on the titanium substrate. HRTEM and Raman results confirmed that the TiO 2 nano-pillar arrays were single crystalline anatase. The controls of morphology, size, and orientation of the nano-pillar could be achieved by varying the solution concentration and hydrothermal temperature. Furthermore, the special morphology of the TiO 2 nano-pillar arrays was caused by the selectively absorption of the tetramethylammonium (TMA) through hydrogen bonds on the lattice planes parallel to (0 0 1) of anatase TiO 2. Less grain boundaries and direct electrical pathway for electron transferring were crucial for the superior photoelectrochemical properties of the single anatase TiO 2 nano-pillar arrays. This approach provides a facile in situ method to synthesize TiO 2 nano-pillar arrays with a special morphology on titanium substrate.

  9. Iron oxide and hydroxide precipitation from ferrous solutions and its relevance to Martian surface mineralogy

    NASA Technical Reports Server (NTRS)

    Posey-Dowty, J.; Moskowitz, B.; Crerar, D.; Hargraves, R.; Tanenbaum, L.

    1986-01-01

    Experiments were performed to examine if the ubiquitousness of a weak magnetic component in all Martian surface fines tested with the Viking Landers can be attributed to ferric iron precipitation in aqueous solution under oxidizing conditions at neutral pH. Ferrous solutions were mixed in deionized water and various minerals were added to separate liquid samples. The iron-bearing additives included hematite, goethite, magnetite, maghemite, lepidocrocite and potassium bromide blank at varying concentrations. IR spectroscopic scans were made to identify any precipitates resulting from bubbling oxygen throughout the solutions; the magnetic properties of the precipitates were also examined. The data indicated that the lepidocrocite may have been preferentially precipitated, then aged to maghemite. The process would account for the presumed thin residue of maghemite on the present Martian surface, long after abundant liquid water on the Martian surface vanished.

  10. Iron oxide and hydroxide precipitation from ferrous solutions and its relevance to Martian surface mineralogy

    NASA Astrophysics Data System (ADS)

    Posey-Dowty, J.; Moskowitz, B.; Crerar, D.; Hargraves, R.; Tanenbaum, L.; Dowty, E.

    1986-04-01

    Experiments were performed to examine if the ubiquitousness of a weak magnetic component in all Martian surface fines tested with the Viking Landers can be attributed to ferric iron precipitation in aqueous solution under oxidizing conditions at neutral pH. Ferrous solutions were mixed in deionized water and various minerals were added to separate liquid samples. The iron-bearing additives included hematite, goethite, magnetite, maghemite, lepidocrocite and potassium bromide blank at varying concentrations. IR spectroscopic scans were made to identify any precipitates resulting from bubbling oxygen throughout the solutions; the magnetic properties of the precipitates were also examined. The data indicated that the lepidocrocite may have been preferentially precipitated, then aged to maghemite. The process would account for the presumed thin residue of maghemite on the present Martian surface, long after abundant liquid water on the Martian surface vanished.

  11. 21 CFR 184.1763 - Sodium hydroxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... hydroxide is prepared commercially by the electrolysis of sodium chloride solution and also by reacting... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium hydroxide. 184.1763 Section 184.1763 Food... GRAS § 184.1763 Sodium hydroxide. (a) Sodium hydroxide (NaOH, CAS Reg. No. 1310-73-2) is also known...

  12. Two competitive nucleation mechanisms of calcium carbonate biomineralization in response to surface functionality in low calcium ion concentration solution

    PubMed Central

    Deng, Hua; Wang, Shuo; Wang, Xiumei; Du, Chang; Shen, Xingcan; Wang, Yingjun; Cui, Fuzhai

    2015-01-01

    Four self-assembled monolayer surfaces terminated with –COOH, –OH, –NH2 and –CH3 functional groups are used to direct the biomineralization processes of calcium carbonate (CaCO3) in low Ca2+ concentration, and the mechanism of nucleation and initial crystallization within 12 h was further explored. On −COOH surface, nucleation occurs mainly via ion aggregation mechanism while prenucleation ions clusters may be also involved. On −OH and −NH2 surfaces, however, nucleation forms via calcium carbonate clusters, which aggregate in solution and then are adsorbed onto surfaces following with nucleation of amorphous calcium carbonate (ACC). Furthermore, strongly negative-charged −COOH surface facilitates the direct formation of calcites, and the −OH and −NH2 surfaces determine the formation of vaterites with preferred crystalline orientations. Neither ACC nor crystalline CaCO3 is observed on −CH3 surface. Our findings present a valuable model to understand the CaCO3 biomineralization pathway in natural system where functional groups composition plays a determining role during calcium carbonate crystallization. PMID:26814639

  13. Two competitive nucleation mechanisms of calcium carbonate biomineralization in response to surface functionality in low calcium ion concentration solution.

    PubMed

    Deng, Hua; Wang, Shuo; Wang, Xiumei; Du, Chang; Shen, Xingcan; Wang, Yingjun; Cui, Fuzhai

    2015-09-01

    Four self-assembled monolayer surfaces terminated with -COOH, -OH, -NH2 and -CH3 functional groups are used to direct the biomineralization processes of calcium carbonate (CaCO3) in low Ca(2+) concentration, and the mechanism of nucleation and initial crystallization within 12 h was further explored. On -COOH surface, nucleation occurs mainly via ion aggregation mechanism while prenucleation ions clusters may be also involved. On -OH and -NH2 surfaces, however, nucleation forms via calcium carbonate clusters, which aggregate in solution and then are adsorbed onto surfaces following with nucleation of amorphous calcium carbonate (ACC). Furthermore, strongly negative-charged -COOH surface facilitates the direct formation of calcites, and the -OH and -NH2 surfaces determine the formation of vaterites with preferred crystalline orientations. Neither ACC nor crystalline CaCO3 is observed on -CH3 surface. Our findings present a valuable model to understand the CaCO3 biomineralization pathway in natural system where functional groups composition plays a determining role during calcium carbonate crystallization. PMID:26814639

  14. Solvation of Dimethyl Succinate in a Sodium Hydroxide Aqueous Solution. A Computational Study

    SciTech Connect

    Sun, Xiuquan; Chang, Tsun-Mei; Cao, Yang; Niwayama, Satomi; Hase, William L.; Dang, Liem X.

    2009-05-07

    Molecular dynamics simulations were carried out to study dimethyl-succinate/water/NaOH solutions. The potential of mean force method is used to determine the transport mechanism of a dimethyl-succinate (a diester) molecule across the aqueous/vapor interface. The computed number density profiles show a strong propensity for the diester molecules to congregate at the interface with the solubility of the diester increasing with increasing NaOH concentration. It is observed that the major contribution to the interfacial solvation free energy minimum is from van der Waals interactions. Thus, even at higher NaOH concentrations, the increasing electrostatic interaction between the diester and ions is not large enough to overcome the Lennard-Jones (LJ) interactions to favor the solvation of diester in bulk solutions. The calculated solvation free energies are found to be -2.6 ~ -3.5 kcal/mol in variant concentrations of NaOH aqueous solutions. These values are in qualitative agreement with the corresponding experimental measurements. The computed surface potential indicates that the contribution of diester molecules to the total surface potential is about 25%, with the major contribution from interfacial water molecules. This work was supported by the US Department of Energy (DOE) Office of Basic Energy Sciences, Chemical Sciences program. Pacific Northwest National Laboratory is operated by Battelle for DOE.

  15. Effects of oxytetracycline in propylene glycol, oxytetracycline in saline solution, and propylene glycol alone on blood ionized calcium and plasma total calcium in sheep.

    PubMed

    Button, C; Mülders, M S

    1984-08-01

    Intravenous injection of oxytetracycline HC1 (OTC) in propylene glycol (PG), OTC in saline solution, and PG alone in sheep had no significant (P less than 0.01) effects on total plasma calcium concentrations over a 60-minute period. In contrast, ionized calcium concentrations in whole blood were significantly (P less than 0.01) depressed for approximately 3 minutes after OTC in PG and OTC in saline solution, IV. A slight depression of ionized calcium concentrations was noticed after injection of PG alone. Seemingly, calcium chelation by OTC may be a major factor in the collapse syndrome of ungulates given preparations containing OTC by rapid IV injection. PMID:6476580

  16. The thermodynamic characteristics of complex formation between calcium ions and L-leucine in aqueous solution

    NASA Astrophysics Data System (ADS)

    Kurochkin, V. Yu.; Chernikov, V. V.; Orlova, T. D.

    2011-04-01

    Complex formation of L-leucine with calcium ions in aqueous solution was studied by potentiometric titration at 298.15 K and ionic strength values I = 0.5, 1.0, and 1.5 (KNO3). The formation of the CaL+ and CaHL2+ complex particles was established and their stability constants were determined. The enthalpies of protolytic equilibria of leucine and formation of calcium ion complexes with leucine were determined calorimetrically at 298.15 K and I = 0.5 (KNO3). The thermodynamic characteristics of complex formation between calcium ions and L-leucine were calculated.

  17. Kinetic-limited etching of magnesium doping nitrogen polar GaN in potassium hydroxide solution

    NASA Astrophysics Data System (ADS)

    Jiang, Junyan; Zhang, Yuantao; Chi, Chen; Yang, Fan; Li, Pengchong; Zhao, Degang; Zhang, Baolin; Du, Guotong

    2016-01-01

    KOH based wet etchings were performed on both undoped and Mg-doped N-polar GaN films grown by metal-organic chemical vapor deposition. It is found that the etching rate for Mg-doped N-polar GaN gets slow obviously compared with undoped N-polar GaN. X-ray photoelectron spectroscopy analysis proved that Mg oxide formed on N-polar GaN surface is insoluble in KOH solution so that kinetic-limited etching occurs as the etching process goes on. The etching process model of Mg-doped N-polar GaN in KOH solution is tentatively purposed using a simplified ideal atomic configuration. Raman spectroscopy analysis reveals that Mg doping can induce tensile strain in N-polar GaN films. Meanwhile, p-type N-polar GaN film with a hole concentration of 2.4 × 1017 cm-3 was obtained by optimizing bis-cyclopentadienyl magnesium flow rates.

  18. Magnetic nanomaterial derived from graphene oxide/layered double hydroxide hybrid for efficient removal of methyl orange from aqueous solution.

    PubMed

    Yang, Zhe; Ji, Shanshan; Gao, Wei; Zhang, Chao; Ren, Lulu; Tjiu, Weng Weei; Zhang, Zheng; Pan, Jisheng; Liu, Tianxi

    2013-10-15

    Magnetic hybrid nanomaterials composed of reduced graphene oxide, zero-valent nickel, and NiAl-mixed metal oxides (rGO/Ni/MMO) have been synthesized by calcining graphene oxide (GO)/layered double hydroxide (LDH) hybrid in nitrogen atmosphere. Structural characterizations demonstrate that with the presence of GO substrate, NiAl-LDHs can be reduced into zero-valent Ni and NiAl-MMOs during calcination. Transmission electron microscopy (TEM) is used to investigate the morphology of the as-prepared hybrid nanomaterials, demonstrating that the introduction of GO substrate prevents the aggregation of LDHs. Magnetism characterization proves the ferromagnetic property of rGO/Ni/MMO hybrid. This magnetic hybrid nanomaterial exhibits excellent adsorption ability toward methyl orange (MO) in aqueous solutions. The kinetics of the adsorption process and the adsorption isotherm are investigated. The MO removal process is found to obey the Redlich-Peterson isotherm model, and its kinetics follows pseudo-second-order rate equation. In addition, the magnetic hybrid also exhibits good recycle ability for MO removal. This novel magnetic hybrid nanomaterial derived from GO/LDH hybrid demonstrates great potential in the applications of water treatment. PMID:23928490

  19. Calcium

    MedlinePlus

    ... body stores more than 99 percent of its calcium in the bones and teeth to help make and keep them ... in the foods you eat. Foods rich in calcium include Dairy products such as milk, cheese, and yogurt Leafy, green vegetables Fish with soft bones that you eat, such as canned sardines and ...

  20. Potassium hydroxide clay stabilization process

    SciTech Connect

    Sydansk, R.

    1981-07-28

    An aqueous solution having potassium hydroxide dissolved therein is injected into a subterranean sandstone formation containing water-sensitive fine particles, including clays. Potassium hydroxide stabilizes the fine particles for a substantial period of time thereby substantially preventing formation permeability damage caused by encroachment of aqueous solutions having a distinct ionic makeup into the treated formation.

  1. Pulpal responses to bacterial contamination following dentin bridging beneath hard-setting calcium hydroxide and self-etching adhesive resin system.

    PubMed

    Kitasako, Yuichi; Ikeda, Masaomi; Tagami, Junji

    2008-04-01

    To evaluate the pulp healing to bacterial contamination beneath a hard-setting calcium hydroxide (DY: Dycal, L.D. Caulk Co.) and a self-etching adhesive resin (2V: Clearfil Liner Bond 2V, Kuraray Medical Inc.) following dentin bridge formation. Class V cavities were prepared on 30 monkey teeth, and the pulps were exposed with a carbide bur through the cavity floor. Each exposed pulp was capped with either DY or 2V. The cavities were restored with a hybrid resin composite. The resin composite was removed at 180 days after capping, and then cavities were left open to the oral environment for 2 weeks to obtain bacteria contamination DY (BDY) and 2V (B2V; n = 10). A non-bacterial-contaminated group capped with DY was used as control. After bacterial challenges, inflammatory cell infiltration, incidence and differentiation of dentin bridges were evaluated histologically. There were significant differences in the presence of inflammatory cell infiltration among all groups (P < 0.05). No moderate or severe inflammatory reaction was found in Group DY. Group BDY showed moderate or severe inflammatory cell infiltration in 50%, and showed four necrotic specimens. Although no statistically significant difference was found in the formation and differentiation of dentin bridges among all groups, tunnel defects in dentin bridges were detected in 70% (DY), 80% (BDY), and 50% (B2V). Group B2V showed a significantly lower presence of inflammatory cell infiltration than Group BDY (P < 0.05). Bonding agent is supposed to seal the exposure site, and the remaining bonding agent on the cavities was effective as the barrier in the dentin bridges after bacterial challenges. PMID:18352925

  2. Management of Cyst-like Periapical Lesions by Orthograde Decompression and Long-term Calcium Hydroxide/Chlorhexidine Intracanal Dressing: A Case Series.

    PubMed

    Santos Soares, Suelleng Maria Cunha; Brito-Júnior, Manoel; de Souza, Flávia Kelly; Zastrow, Eduardo Von; Cunha, Carla Oliveira da; Silveira, Frank Ferreira; Nunes, Eduardo; César, Carlos Augusto Santos; Glória, José Cristiano Ramos; Soares, Janir Alves

    2016-07-01

    Cyst-like periapical lesions should be treated initially with conservative nonsurgical procedures. In this case series, we describe the clinical and radiographic outcomes of large cyst-like lesions that were treated by orthograde decompression and long-term intracanal use of calcium hydroxide [Ca(OH)2] mixed with 2% chlorhexidine digluconate. Ten cases of cyst-like periapical lesions involving 15 teeth from 10 patients were selected. Maximal radiographic diameters of the lesions ranged from 11 to 28 mm. Nonsurgical procedures were performed, including apical patency, orthograde puncture of cyst-like exudates, chemomechanical preparation, and placement of intracanal Ca(OH)2/CHX dressings, which were periodically replaced during 6-10 months. The root canals were then filled with gutta-percha and sealer. The follow-up periods ranged from 6 to 24 months, and the outcome was classified as healed, healing, or failure. Nine lesions drained copious exudates after canal patency. One lesion only drained bloody serous exudate after periapical overinstrumentation. In 9 patients, intracanal exudation ceased in the first follow-up visit. At the 24-month follow-up, 6 lesions (60.0%) had healed, and 3 lesions (30.0%) were healing, with the corresponding patients being without clinical signs or symptoms. The case of treatment failure was submitted to surgical treatment. Microscopically, the lesion appeared to be an apical cyst with exuberant extraradicular bacterial biofilms attached to the sectioned root apex. This case series supports the use of nonsurgical methods to resolve larger cyst-like periapical lesions. PMID:27325458

  3. Simplified regional citrate anticoagulation using a calcium-containing replacement solution for continuous venovenous hemofiltration.

    PubMed

    Zhang, Ling; Liao, Yujie; Xiang, Jin; Qin, Wei; Wu, Xiaodong; Tang, Yi; Yang, Yingying; Chen, Zhiwen; Fu, Ping

    2013-06-01

    Regional citrate anticoagulation (RCA) is not widely used because it requires complex therapeutic modalities, a specialized calcium-free replacement solution, and continuous intravenous calcium infusion. We designed a simplified protocol for RCA using a commercial calcium-containing replacement solution for continuous venovenous hemofiltration (CVVH). Thirty-six patients were treated with RCA-based pre-dilution CVVH using a calcium-containing replacement solution (ionized calcium 1.50 mmol/L). We pumped a 4 % trisodium citrate solution into the arterial line of extracorporeal circulation at a starting rate of 200 mL/h while adjusting the rate to achieve a post-filter ionized calcium level of between 0.25 and 0.5 mmol/L. The initial blood flow was set at 150 mL/min. The replacement solution was delivered at 35 mL/kg/h. We measured the serum and effluent citrate concentration during CVVH at 0, 24, 48, and 72 h. The mean hemofilter survival was 61.3 ± 21.6 h (range 14-122 h). The mean 4 % trisodium citrate solution pumped was 207 (190-230) mL/h, and the mean pre-filter and post-filter ionized calcium levels were 0.96-1.02 and 0.34-0.38 mmol/L, respectively. Ninety-two, 63, and 48 % of the hemofilters were patent at 24, 48, and 72 h. The mean serum citrate concentration was not significantly different at 24, 48, and 72 h. No bleeding episodes were found, and no patient showed the symptoms and signs of hypocalcemia or citrate toxicity. Our simplified RCA protocol using a calcium-containing replacement solution for CVVH is effective and safe, and obviates the need for a separate peripheral or central venous catheter for continuous intravenous calcium infusion. PMID:23271571

  4. Phase Stability of Chromium(III) Oxide Hydroxide in Alkaline Sodium Phosphate Solutions

    SciTech Connect

    S.E. Ziemniak; E.P. Opalka

    2003-07-08

    Grimaldiite ({alpha}-CrOOH) is shown to transform to a sodium-chromium(III)-hydroxyphosphate compound (SCHP) in alkaline sodium phosphate solutions at elevated temperatures via CrOOH(s) + 4Na{sup +} + 2HPO{sub 4}{sup 2-} = Na{sub 4}Cr(OH)(PO{sub 4}){sub 2}(s) + H{sub 2}O. X-ray diffraction analyses indicate that SCHP possesses an orthorhombic lattice having the same space group symmetry (Ibam, No.72) as sodium ferric hydroxyphosphate. A structurally-consistent designation for SCHP is Na{sub 3}Cr(PO{sub 4}){sub 2} {center_dot} NaOH; the molar volume of SCHP is estimated to be 1552 cm{sup 3}. The thermodynamic equilibrium for the above reaction was defined in the system Na{sub 2}O-P{sub 2}O{sub 5}-Cr{sub 2}O{sub 3}-H{sub 2}O for Na/P molar ratios between 2.0 and 2.4. On the basis of observed reaction threshold values for sodium phosphate concentration and temperature, the standard molar entropy (S{sup o}), heat capacity (C{sub p}{sup o}) and free energy of formation ({Delta}G{sub f}{sup o}) for SCHP were calculated to be 690 J/(mol-K), 622 J/(mol-K) and -3509.97 kJ/mol, respectively.

  5. Friction and wear of iron and nickel in sodium hydroxide solutions

    NASA Technical Reports Server (NTRS)

    Rengstorff, G. W. P.; Miyoshi, K.; Buckley, D. H.

    1982-01-01

    A loaded spherical aluminum oxider rider was made to slide, while in various solutions, on a flat iron or nickel surface reciprocate a distance of 1 cm. Time of experiments was 1 hr during which the rider passed over the rider passed over the center section of the track 540 times. Coefficients of friction were measured throughout the experiments. Wear was measured by scanning the track with a profilometer. Analysis of some of the wear tracks included use of the SEM (scanning electron microscrope) and XPS (X-ray photoelectron spectroscopy). Investigated were the effect of various concentractions of NaOH and of water. On iron, increasing NaOH concentration above 0.01 N caused the friction and wear to decrease. This decrease is accompanied by a decrease in surface concentration of ferric oxide (Fe2O3) while more complex iron-oxygen compounds, not clearly identified, also form. At low concentrations of NaOH, such as 0.01 N, where the friction is high, the wear track is badely torn up and the surface is broken. At high concentration, such as 10 N, where the friction is low, the wear track is smooth. The general conclusion is that NaOH forms a protective, low friction film on iron which is destroyed by wear at low concentrations but remains intact at high concentrations of NaOH. Nickel behaves differently than iron in that only a little NaOH gives a low coefficient of friction and a surface which, although roughened in the wear track, remains intact.

  6. Friction and wear of iron and nickel in sodium hydroxide solutions

    NASA Technical Reports Server (NTRS)

    Rengstorff, G. P.; Miyoshi, K.; Buckley, D. H.

    1983-01-01

    A loaded spherical aluminum oxider rider was made to slide, while in various solutions, on a flat iron or nickel surface reciprocate a distance of 1 cm. Time of experiments was 1 hr during which the rider passed over the center section of the track 540 times. Coeficients of friction were measured throughout the experiments. Wear was measured by scanning the track with a profilometer. Analysis of some of the wear tracks included use of the SEM (scanning electron microscope) and XPS (X-ray photoelectron spectroscopy). Investigated were the effect of various concentrations of NaOH and of water. On iron, increasing NaOH concentration above 0.01 N caused the friction and wear to decrease. This decrease is accompanied by a decrease in surface concentration of ferric oxide (Fe2O3) while more complex iron-oxygen compounds, not clearly identified, also form. At low concentrations of NaOH, such as 0.01 N, where the friction is high, the wear track is badly torn up and the surface is broken. At high concentration, such as 10 N, where the friction is low, the wear track is smooth. The general conclusion is that NaOH forms a protective, low friction film on iron which is destroyed by wear at low concentrations but remains intact at high conentrations of NaOH. Nickel behaves differently than iron in that only a little NaOH gives a low coefficient of friction and a surface which, although roughened in the wear track, remains intact. Previously announced in STAR as N83-10171

  7. Determination of trace vitamin C by ion-pair HPLC with UV detection in calcium gluconate and vitamin C compound oral solution.

    PubMed

    Hu, Liandong; Li, Li; Luo, Zhaoliang; Yang, Jianxue; Liu, Wei

    2012-02-01

    A sensitive and specific reversed-phase high-performance liquid chromatographic method with ultraviolet detection was developed for the determination of vitamin C, using tetrabutylammonium hydroxide as an ion-pair reagent in a compound oral solution containing 100 mg/mL calcium gluconate and 1.25 mg/mL vitamin C. The aqueous phase contained 0.005 mol/L tetrabutylammonium hydroxide and the mobile phase consisted of a mixture of the aqueous phase-methanol (80:20, v/v, pH 6.0 adjusted by phosphoric acid). The linearity, sensitivity and specificity, accuracy, and stability of the procedure were evaluated. The calibration curves for vitamin C were linear in the range of 10.0-100.0 µg/mL. The percentage coefficient of variation of the quantitative analysis of the vitamin C in the products analysis was within 5%. The method was successfully applied to determine the stability of vitamin C in the compound oral solution. It was found that the vitamin C peak was symmetrical and the column efficiency was high. The method is simple and suitable for stability testing of a low concentration of vitamin C preparation. PMID:22298758

  8. New treatment method for boron in aqueous solutions using Mg-Al layered double hydroxide: Kinetics and equilibrium studies.

    PubMed

    Kameda, Tomohito; Oba, Jumpei; Yoshioka, Toshiaki

    2015-08-15

    Mg-Al layered double hydroxides (LDHs) intercalated with NO3(-) (NO3 · Mg - Al LDHs) and with Cl(-) (Cl · Mg - Al LDHs) were found to take up boron from aqueous solutions. Boron was removed by anion exchange of B(OH)4(-) in solution with NO3(-) and Cl(-) intercalated in the interlayer of the LDH. Using three times the stoichiometric quantity of NO3 · Mg-Al LDH, the residual concentration of B decreased from 100 to 1.9 mg L(-1) in 120 min. Using five times the stoichiometric quantity of Cl · Mg - Al LDH, the residual concentration of B decreased from 100 to 5.6 mg L(-1) in 120 min. It must be emphasized that, in both cases, the residual concentration of B was less than the effluent standards in Japan (10 mg L(-1)). The rate-determining step of B removal by the NO3 · Mg - Al and Cl · Mg - Al LDHs was found to be chemical adsorption involving anion exchange of B(OH)4(-) with intercalated NO3(-) and Cl(-). The removal of B was well described by a pseudo second-order kinetic equation. The adsorption of B by NO3 · Mg - Al LDH and Cl · Mg - Al LDH followed a Langmuir-type adsorption. The values of the maximum adsorption and the equilibrium adsorption constant were 3.6 mmol g(-1) and 1.7, respectively, for NO3 · Mg - Al LDH, and 3.8 mmol g(-1) and 0.7, respectively, for Cl · Mg-Al LDH. The B(OH)4(-) in B(OH)4 · Mg - Al LDH produced by removal of B was found to undergo anion exchange with NO3(-) and Cl(-) in solution. The NO3 · Mg - Al and Cl · Mg - Al LDHs obtained after this regeneration treatment were able to remove B from aqueous solutions, indicating the possibility of recycling NO3 · Mg - Al and Cl · Mg - Al LDHs for B removal. PMID:25827268

  9. A study of the electrochemistry of nickel hydroxide electrodes with various additives

    NASA Astrophysics Data System (ADS)

    Zhu, Wen-Hua; Ke, Jia-Jun; Yu, Hong-Mei; Zhang, Deng-Jun

    Nickel composite electrodes (NCE) with various additives are prepared by a chemical impregnation method from nitrate solutions on sintered porous plaques. The electrochemical properties, such as utilization of active material, swelling and the discharge potential of the nickel oxide electrode (NOE) are determined mainly through the composition of the active material and the characteristics of nickel plaques. Most additives (Mg, Ca, Sr, Ba, Zn, Cd, Co, Li and Al hydroxide) exert effects on the discharge potential and swelling of the NOE. Chemical co-precipitation with the addition of calcium, zinc, magnesium and barium hydroxide increases the discharge potential by more than 20 mV, but that with zinc hydroxide results in an obvious decrease of active-material utilization and that with calcium and magnesium hydroxide produces a larger increase of electrode thickness. The effects of anion additives are also examined. Less than 1% mol of NiS in the active material increases the discharge potential. Cadmium, cobalt and zinc hydroxide are excellent additives for preventing swelling of the NCE. Slow voltammetry (0.2 mV s -1) in 6 M KOH is applied to characterize the oxygen-evolving potential of the NCE. The difference between the oxygen-evolution potential and the potential of the oxidation peak for the NCE with additives of calcium, lithium, barium and aluminium hydroxide is at least + 60 mV.

  10. Calcium

    MedlinePlus

    ... milligrams) of calcium each day. Get it from: Dairy products. Low-fat milk, yogurt, cheese, and cottage ... lactase that helps digest the sugar (lactose) in dairy products, and may have gas, bloating, cramps, or ...

  11. Comparison of surface properties between kaolin and metakaolin in concentrated lime solutions.

    PubMed

    Konan, K L; Peyratout, C; Smith, A; Bonnet, J-P; Rossignol, S; Oyetola, S

    2009-11-01

    The surface adsorption of calcium hydroxide onto kaolin and metakaolin was investigated by monitoring with atomic emission spectroscopy and pH measurements the amounts of ions left in solution after exposing clays to calcium hydroxide solutions of various concentrations. Both clays adsorb calcium and hydroxyl ions but differently. Kaolin adsorbs calcium hydroxide not only at the edges of the clay particles but also onto the basal faces. The adsorbed hydrated calcium ions form a layer on the clay particle surfaces, preventing further dissolution of the clay mineral platelet. Metakaolin shows high pozzolanic activity, which provides the quick formation of hydrated phases at the interfaces between metakaolin and lime solutions. The nature of the hydration products has been investigated using X-ray diffraction (XRD) and differential thermal analysis (DTA). The most important hydrated phases like CSH (hydrated calcium silicate) and C(2)ASH(8) (gehlenite) have been identified. PMID:19682702

  12. CO2 Extraction from Ambient Air Using Alkali-Metal Hydroxide Solutions Derived from Concrete Waste and Steel Slag

    NASA Astrophysics Data System (ADS)

    Stolaroff, J. K.; Lowry, G. V.; Keith, D. W.

    2003-12-01

    enacting the scheme is presented, along with capital and operational cost estimates. The system is found to be profitable for carbon credits above \\5/ton; C. Many findings in this research apply to a more general set of systems which capture CO_2$ from the air for sequestration. The metal-hydroxide solution in these systems is regenerated on site, allowing application of this scheme on as large a scale as needed. Implications of this study's findings for these more general carbon-capture systems is discussed.

  13. Calcium Fluoride Precipitation and Deposition From 12 mmol/L Fluoride Solutions With Different Calcium Addition Rates

    PubMed Central

    Markovic, M; Takagi, S; Chow, LC; Frukhtbeyn, S

    2009-01-01

    The effects of different Ca-addition rates on calcium fluoride (CaF2) precipitation and deposition were investigated in 12 mmol/L sodium fluoride solutions to which 0.1 mol/L calcium chloride solution was continuously added at average rates of (5, 7.5, 10, 12.5, 15 or 20) mmol L−1 min−1. The changes in ionic fluoride and calcium concentrations, as well as turbidity, were continuously recorded by F and Ca electrodes, and a fiber optic based spectrophotometer, respectively. The F− concentration decreased and turbidity increased with time indicating precipitation of CaF2. For the systems with Ca-addition rates of (5, 7.5, 10, 12.5, 15, and 20) mmol L−1 min−1, the 1 min CaF2 depositions in the model substrate (cellulose filter paper, pores 0.2 µm) expressed as mean ± SD of deposited F per substrate surface area were (3.78 ± 0.31, 11.45 ± 0.89, 9.31 ± 0.68, 8.20 ± 0.56, 6.63 ± 0.43, and 2.09 ± 0.28) µg/cm2, respectively (n = 10 for each group). The 1-min F depositions did not show positive correlation to Ca-addition rates. The lowest 1-min F deposition was obtained in the systems with the highest Ca-addition rate of 20 mmol L−1 min−1 for which CaF2 precipitation rate reached the maximum value of 0.31 mmol L−1 s−1 almost immediately after beginning of reaction (6 s). The largest 1-min F depositions were obtained from the systems with Ca addition rates of (7.5 to 12.5) mmol L−1 min−1 in which CaF2 precipitation rates continuously increased reaching the maximum values of (0.13 to 0.20) mmol L−1 s−1 after (18 to 29) s, respectively. The 1-min F depositions were greatly enhanced in comparison with the control F solutions that did not have continuous Ca-addition. This indicates that continuous Ca addition that controls the rate of CaF2 formation could be a critical factor for larger F depositions from F solutions. The efficacy of conventional F mouthrinses could be improved with addition of a substance that continuously releases Ca.

  14. A prospective, open, comparative study of 5% potassium hydroxide solution versus cryotherapy in the treatment of genital warts in men*

    PubMed Central

    Camargo, Caio Lamunier de Abreu; Belda, Walter; Fagundes, Luiz Jorge; Romiti, Ricardo

    2014-01-01

    BACKGROUND Genital warts are caused by human papillomavirus infection and represent one of the most common sexually transmitted diseases. Many infections are transient but the virus may recur, persist, or become latent. To date, there is no effective antiviral treatment to eliminate HPV infection and most therapies are aimed at the destruction of visible lesions. Potassium hydroxide is a strong alkali that has been shown to be safe and effective for the treatment of genital warts and molluscum contagiosum. Cryotherapy is considered one of the most established treatments for genital warts. No comparative trials have been reported to date on the use of potassium hydroxide for genital warts. OBJECTIVE A prospective, open-label, randomized clinical trial was conducted to compare topical potassium hydroxide versus cryotherapy in the treatment of genital warts affecting immunocompetent, sexually active men. METHODS Over a period of 10 months, 48 patients were enrolled. They were randomly divided into two groups and selected on an alternative basis for either potassium hydroxide therapy or cryotherapy. While response to therapy did not differ substantially between both treatment modalities, side effects such as local pain and post-treatment hypopigmentation were considerably more prevalent in the groups treated using cryotherapy. RESULT In our study, potassium hydroxide therapy proved to be at least as effective as cryotherapy and offered the benefit of a better safety profile. CONCLUSION Topical 5% potassium hydroxide presents an effective, safe, and low-cost treatment modality for genital warts in men and should be included in the spectrum of therapies for genital warts. PMID:24770498

  15. The Use of Light/Chemically Hardened Polymethylmethacrylate, Polyhydroxyethylmethacrylate, and Calcium Hydroxide Graft Material in Combination With Polyanhydride Around Implants in Minipigs: Part I: Immediate Stability and Function

    PubMed Central

    Hasturk, Hatice; Kantarci, Alpdogan; Ghattas, Mazen; Schmidt, Marcella; Giordano, Russell A.; Ashman, Arthur; Diekwisch, Thomas G.; Van Dyke, Thomas

    2015-01-01

    Background The present study is designed as a proof-of-concept study to evaluate light/chemical hardening technology and a newly formulated polymethylmethacrylate, polyhydroxyethylmethacrylate, and calcium hydroxide (PPCH) plus polyanhydride (PA) (PPCH-PA) composite graft material as a bone substitute compared to positive and negative controls in a minipig model. Methods PPCH-PA (composite graft); PPCH alone (positive control), PA alone (positive control), and no graft (negative control) were compared. Four mandibular premolar teeth per quadrant were extracted; a total of 48 implants were placed into sockets in three minipigs. Abutments were placed protruding into the oral cavity 4 mm in height for immediate loading. Crestal areas and intrabony spaces were filled with PPCH-PA, PPCH, or PA using a three-phase delivery system in which all graft materials were hardened by a light cure. In the negative control group, implant sites were left untreated. At 12 weeks, block sections containing implants were obtained. Evaluations included periodontal probing, pullout-force load, and stability measurements to determine implant stability, radiographs to examine bone levels, and scanning electron microscopy (SEM)–energy-dispersed spectroscopy to determine bone-to-implant contact. Results Probing measurements did not reveal any pathologic pocket formation or bone loss. Radiographs revealed that immediate implant placement and loading resulted in bone at or slightly apical to the first thread of the implant in all groups at 12 weeks. Stability test values showed a relative clinical stability for all implants (range: −7 to +1); however, implants augmented with PPCH-PA exhibited a statistically significantly greater stability compared to all other groups (P <0.05). The newly formed bone in PPCH-PA–treated sites was well organized with less marrow spaces and well-distributed osteocytes. SEM revealed a tighter implant–socket interface in the PPCH-PA group compared to other

  16. Spectroscopic and electrochemical studies of selected lanthanides and actinides in concentrated aqueous carbonate and carbonate-hydroxide solutions and in molten dimethyl sulfone

    SciTech Connect

    Varlashkin, P.G.

    1985-03-01

    Electrochemical and spectroscopic studies of neptunium, plutonium, americium, californium, and terbium in concentrated aqueous carbonate and carbonate-hydroxide solutions have been carried out. Changes in the absorption spectra of Np(VII), Np(V), Pu(VI), Pu(V), Am(VI), and Am(V) in concentrated Na/sub 2/CO/sub 3/ solution and in the formal potentials of the Np(VI)/Np(V) and Pu(VI)/Pu(V) couples as a function of pH were observed. Heptavalent neptunium in concentrated Na/sub 2/CO/sub 3/ solution could only be producted at pH values close to or greater than 14. Plutonium(VII) in 2 M Na/sub 2/CO/sub 3/ solution could only be produced at hydroxide ion concentrations in excess of about 2.5 M. The complexation of Np(VII) and Pu(VII) in Na/sub 2/CO/sub 3/-NaOH solution seems to be mainly by hydroxide ions. Neptunium(IV) and plutonium(IV) are insoluble in Na/sub 2/CO/sub 3/ solution above ca. pH 11-12. Neptunium(III) in carbonate solution is rapidly oxidized by water to Np(IV). Plutonium(III) is insoluble in Na/sub 2/CO/sub 3/ solution. In K/sub 2/CO/sub 3/ solution Pu(III) is stable to oxidation by water but is very sensitive to air oxidation. The redox properties of Cf(III) in Na/sub 2/CO/sub 3/ and K/sub 2/CO/sub 3/ solutions at pH values from 8 to 14 were investigated. The oxidation of terbium(III) in K/sub 2/CO/sub 3/-KOH solution was studied. Spectroscopic and electrochemical studies of cerium, samarium, europium, ytterbium, uranium, neptunium, plutonium, and americium in molten dimethyl sulfone (DMSO/sub 2/) at 400 K were performed. Differences in the DMSO/sub 2/ solution absorption spectra of trivalent Sm, Eu, and Yb and divalent Eu compared with those in aqueous solution were observed. Complexation effects on the spectra of Ce(III), Ce(IV), U(VI), Np(VI), Pu(VI), and Am(VI) are more noticeable in poorly coordinating DMSO/sub 2/ than they are in water. 123 references, 54 figures, 11 tables.

  17. Precipitation of calcium carbonate in aqueous solutions in presence of ethylene glycol and dodecane.

    NASA Astrophysics Data System (ADS)

    Natsi, Panagiota D.; Rokidi, Stamatia; Koutsoukos, Petros G.

    2015-04-01

    The formation of calcium carbonate (CaCO3) in aqueous supersaturated solutions has been intensively studied over the past decades, because of its significance for a number of processes of industrial and environmental interest. In the oil and gas production industry the deposition of calcium carbonate affects adversely the productivity of the wells. Calcium carbonate scale deposits formation causes serious problems in water desalination, CO2 sequestration in subsoil wells, in geothermal systems and in heat exchangers because of the low thermal coefficient of the salt. Amelioration of the operational conditions is possible only when the mechanisms underlying nucleation and crystal growth of calcium carbonate in the aqueous fluids is clarified. Given the fact that in oil production processes water miscible and immiscible hydrocarbons are present the changes of the dielectric constant of the fluid phase has serious impact in the kinetics of calcium carbonate precipitation, which remains largely unknown. The problem becomes even more complicated if polymorphism exhibited by calcium carbonate is also taken into consideration. In the present work, the stability of aqueous solutions supersaturated with respect to all calcium carbonate polymorphs and the subsequent kinetics of calcium carbonate precipitation were measured. The measurements included aqueous solutions and solutions in the presence of water miscible (ethylene glycol, MEG) and water immiscible organics (n-dodecane). All measurements were done at conditions of sustained supersaturation using the glass/ Ag/AgCl combination electrode as a probe of the precipitation and pH as the master variable for the addition of titrant solutions with appropriate concentration needed to maintenance the solution supersaturation. Initially, the metastable zone width was determined from measurements of the effect of the solution supersaturation on the induction time preceding the onset of precipitation at free-drift conditions. The

  18. Aluminum Hydroxide

    MedlinePlus

    ... penicillamine (Cuprimine, Depen), prednisone (Deltasone, Orasone), products containing iron, tetracycline (Sumycin, Tetracap, and others), ticlopidine (Ticlid), and vitamins.be aware that aluminum hydroxide may interfere with other medicines, making them less effective. Take your other medications 1 ...

  19. NICKEL HYDROXIDES

    SciTech Connect

    MCBREEN,J.

    1997-11-01

    Nickel hydroxides have been used as the active material in the positive electrodes of several alkaline batteries for over a century. These materials continue to attract a lot of attention because of the commercial importance of nickel-cadmium and nickel-metal hydride batteries. This review gives a brief overview of the structure of nickel hydroxide battery electrodes and a more detailed review of the solid state chemistry and electrochemistry of the electrode materials. Emphasis is on work done since 1989.

  20. Swelling/deswelling mechanism of calcium alginate gel in aqueous solutions.

    PubMed

    Saitoh, S; Araki, Y; Kon, R; Katsura, H; Taira, M

    2000-12-01

    To elucidate the mechanism of dimensional changes in alginate impression in solutions, the relationship between the ion concentrations in three types of solutions (nonelectrolyte and monovalent and divalent metallic salts) and change in gel volume was examined. The gel in the monovalent metallic salt solution expanded and a decrease in monovalent cation and an increase in Ca2+ were observed. This suggests that the crosslinking density of the gel reduced due to dissociation of Ca2+ from the calcium alginate gel. In divalent metallic salt solutions, the shrinkage occurred according to crosslinking of unreacted residue. In the nonelectrolytic solution, gel, neither ethylene glycol nor acetonitrile showed any volume changes, while that in glutaraldehyde contracted. It is speculated that the former two solutions were affected by the fact that the gel has no semipermeability, and that the latter result was due to chemical interaction between the gel and solution. PMID:11816370

  1. Efficient Sorption and Removal of Perfluoroalkyl Acids (PFAAs) from Aqueous Solution by Metal Hydroxides Generated in Situ by Electrocoagulation.

    PubMed

    Lin, Hui; Wang, Yujuan; Niu, Junfeng; Yue, Zhihan; Huang, Qingguo

    2015-09-01

    Removal of environmentally persistent perfluoroalkyl acids (PFAAs), that is, perfluorooctanesulfonate (PFOS) and perfluorocarboxylic acids (PFCAs, C4 ∼ C10) were investigated through sorption on four metal hydroxide flocs generated in situ by electrocoagulation in deionized water with 10 mM NaCl as supporting electrolyte. The results indicated that the zinc hydroxide flocs yielded the highest removal efficiency with a wide range concentration of PFOA/PFOS (1.5 μM ∼ 0.5 mM) at the zinc dosage <150 mg L(-1) with the energy consumption <0.18 Wh L(-1). The sorption kinetics indicated that the zinc hydroxide flocs had an equilibrium adsorbed amount (qe) up to 5.74/7.69 mmol g(-1) (Zn) for PFOA/PFOS at the initial concentration of 0.5 mM with an initial sorption rate (v0) of 1.01 × 10(3)/1.81 × 10(3) mmol g(-1) h(-1). The sorption of PFOA/PFOS reached equilibrium within <10 min. The sorption mechanisms of PFAAs on the zinc hydroxide flocs were proposed based on the investigation of various driving forces. The results indicated that the hydrophobic interaction was primarily responsible for the PFAAs sorption. The electrocoagulation process with zinc anode may have a great potential for removing PFAAs from industrial wastewater as well as contaminated environmental waterbody. PMID:26244813

  2. Collapse of sodium polyacrylate chains in calcium salt solutions

    NASA Astrophysics Data System (ADS)

    Schweins, R.; Huber, K.

    The sodium salt of polyacrylic acid (NaPA) precipitates in the presence of Ca^{2+}-ions. This phase behaviour can be represented by a phase diagram where the critical NaPA concentration is plotted versus the critical Ca^{2+} concentration resulting in a straight line as a phase boundary. The location of this phase boundary is influenced by the presence of an inert monovalent salt like NaCl. The present contribution focuses on the coil dimensions of NaPA chains in dilute aqueous solution corresponding to the one phase region of such a phase diagram. A variety of parameters with which the size and shape of the polyelectrolyte chains can be modulated are revealed. Approaching the phase boundary by decreasing the NaPA concentration at a constant Ca^{2+} content leads to a collapse of the NaPA chains. Combined static and dynamic light scattering suggests a compact spherical shape as the final state of this transition, both in 0.1 M NaCl and in 0.01 M NaCl. In the lower NaCl concentration, indication is presented for the existence of a cigar or pearl necklace like intermediate. Most strikingly, the collapsed chains can be reexpanded by increasing the concentration of inert NaCl at constant content of NaPA and Ca^{2+}. Clearly, excessive Na+-ions displace the Ca^{2+}-ions from the NaPA chains.

  3. Simulation of carbon dioxide absorption by sodium hydroxide solution in a packed bed and studying the effect of operating parameters on absorption

    SciTech Connect

    Yazdanbakhsh, Farzad; Soltani Goharrizi, Ata'ollah; Hashemipour Rafsanjani, Hassan

    2007-07-01

    Available in abstract form only. Full text of publication follows: In this study. simulation of carbon dioxide absorption by Sodium Hydroxide solution in a packed bed has been investigated. At first, mass and energy balances were applied around a differential height of the bed. So, the governing equations were obtained. Surface renewal theory by Danckwerts was used to represent the mass transfer operation Finally, by changing the operating parameters like solvent temperature, inlet gas composition pressure and height of the bed, the effect of these parameters on the absorption and the composition of carbon dioxide in exit stream have been investigated. (authors)

  4. Structural Properties of the Cr(III)-Fe(III) (Oxy)hydroxide Compositional Series: Insights for a Nanomaterial "Solid Solution"

    SciTech Connect

    Michel, Y.; Michel, F; Zhang, L; Harrington, R; Parise, J; Reeder, R

    2010-01-01

    Chromium(III) (oxy)hydroxide and mixed Cr(III)-Fe(III) (oxy)hydroxides are environmentally important compounds for controlling chromium speciation and bioaccessibility in soils and aquatic systems and are also industrially important as precursors for materials and catalyst synthesis. However, direct characterization of the atomic arrangements of these materials is complicated because of their amorphous X-ray properties. This study involves synthesis of the complete Cr(III)-Fe(III) (oxy)hydroxide compositional series, and the use of complementary thermal, microscopic, spectroscopic, and scattering techniques for the evaluation of their structural properties. Thermal analysis results show that the Cr end member has a higher hydration state than the Fe end member, likely associated with the difference in water exchange rates in the first hydration spheres of Cr(III) and Fe(III). Three stages of weight loss are observed and are likely related to the loss of surface/structural water and hydroxyl groups. As compared to the Cr end member, the intermediate composition sample shows lower dehydration temperatures and a higher exothermic transition temperature. XANES analysis shows Cr(III) and Fe(III) to be the dominant oxidation states. XANES spectra also show progressive changes in the local structure around Cr and Fe atoms over the series. Pair distribution function (PDF) analysis of synchrotron X-ray total scattering data shows that the Fe end member is nanocrystalline ferrihydrite with an intermediate-range order and average coherent domain size of 27 {angstrom}. The Cr end member, with a coherent domain size of 10 {angstrom}, has only short-range order. The PDFs show progressive structural changes across the compositional series. High-resolution transmission electron microscopy (HRTEM) results also show the loss of structural order with increasing Cr content. These observations provide strong structural evidence of chemical substitution and progressive structural

  5. Surface reaction characteristics at low temperature synthesis BaTiO 3 particles by barium hydroxide aqueous solution and titanium tetraisopropoxide

    NASA Astrophysics Data System (ADS)

    Zeng, Min

    2011-05-01

    Well-crystallized cubic phase BaTiO 3 particles were prepared by heating the mixture of barium hydroxide aqueous solution and titania derived from the hydrolysis of titanium isopropoxide (TTIP) at 328 K, 348 K or 368 K for 24 h. The morphology and size of obtained particles depended on the reaction temperature and the Ba(OH) 2/TTIP molar ratio. By the direct hydrolytic reaction of titanium tetraisopropoxide, the high surface area titania (TiO 2) was obtained. The surface adsorption characteristics of the titania particles had been studied with different electric charges OH - ions or H + ions. The formation mechanism and kinetics of BaTiO 3 were examined by measuring the concentration of [Ba 2+] ions in the solution during the heating process. The experimental results showed that the heterogeneous nucleation of BaTiO 3 occurred on the titania surface, according to the Avrami's equation.

  6. Dehydration and crystallization of amorphous calcium carbonate in solution and in air

    PubMed Central

    Ihli, Johannes; Wong, Wai Ching; Noel, Elizabeth H.; Kim, Yi-Yeoun; Kulak, Alexander N.; Christenson, Hugo K.; Duer, Melinda J.; Meldrum, Fiona C.

    2014-01-01

    The mechanisms by which amorphous intermediates transform into crystalline materials are poorly understood. Currently, attracting enormous interest is the crystallization of amorphous calcium carbonate, a key intermediary in synthetic, biological and environmental systems. Here we attempt to unify many contrasting and apparently contradictory studies by investigating this process in detail. We show that amorphous calcium carbonate can dehydrate before crystallizing, both in solution and in air, while thermal analyses and solid-state nuclear magnetic resonance measurements reveal that its water is present in distinct environments. Loss of the final water fraction—comprising less than 15% of the total—then triggers crystallization. The high activation energy of this step suggests that it occurs by partial dissolution/recrystallization, mediated by surface water, and the majority of the particle then crystallizes by a solid-state transformation. Such mechanisms are likely to be widespread in solid-state reactions and their characterization will facilitate greater control over these processes. PMID:24469266

  7. The use of physiological solutions or media in calcium phosphate synthesis and processing.

    PubMed

    Tas, A Cuneyt

    2014-05-01

    This review examined the literature to spot uses, if any, of physiological solutions/media for the in situ synthesis of calcium phosphates (CaP) under processing conditions (i.e. temperature, pH, concentration of inorganic ions present in media) mimicking those prevalent in the human hard tissue environments. There happens to be a variety of aqueous solutions or media developed for different purposes; sometimes they have been named as physiological saline, isotonic solution, cell culture solution, metastable CaP solution, supersaturated calcification solution, simulated body fluid or even dialysate solution (for dialysis patients). Most of the time such solutions were not used as the aqueous medium to perform the biomimetic synthesis of calcium phosphates, and their use was usually limited to the in vitro testing of synthetic biomaterials. This review illustrates that only a limited number of research studies used physiological solutions or media such as Earle's balanced salt solution, Bachra et al. solutions or Tris-buffered simulated body fluid solution containing 27mM HCO3(-) for synthesizing CaP, and these studies have consistently reported the formation of X-ray-amorphous CaP nanopowders instead of Ap-CaP or stoichiometric hydroxyapatite (HA, Ca10(PO4)6(OH)2) at 37°C and pH 7.4. By relying on the published articles, this review highlights the significance of the use of aqueous solutions containing 0.8-1.5 mMMg(2+), 22-27mM HCO3(-), 142-145mM Na(+), 5-5.8mM K(+), 103-133mM Cl(-), 1.8-3.75mM Ca(2+), and 0.8-1.67mM HPO4(2-), which essentially mimic the composition and the overall ionic strength of the human extracellular fluid (ECF), in forming the nanospheres of X-ray-amorphous CaP. PMID:24389317

  8. Production of edible carbohydrates from formaldehyde in a spacecraft. pH variations in the calcium hydroxide catalyzed formose reaction. Final Report, 1 Jul. 1973 - 30 Jun. 1974. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Weiss, A. H.; Kohler, J. T.; John, T.

    1974-01-01

    The study of the calcium hydroxide catalyzed condensation of formaldehyde was extended to a batch reactor system. Decreases in pH were observed, often in the acid regime, when using this basic catalyst. This observation was shown to be similar to results obtained by others using less basic catalysts in the batch mode. The relative rates of these reactions are different in a batch reactor than in a continuous stirred tank reactor. This difference in relative rates is due to the fact that at any degree of advancement in the batch system, the products have a history of previous products, pH, and dissolved catalyst. The relative rate differences can be expected to yield a different nature of product sugars for the two types of reactors.

  9. Freezing of snow layers saturated with a calcium chloride aqueous solution

    NASA Astrophysics Data System (ADS)

    Sugawara, M.; Tago, M.; Nozawa, R.; Beer, H.

    2002-09-01

    This paper provides a basic information to control snow layers on roads or runways in order to maintain road safety. The snow saturated with a calcium chloride aqueous solution is initially in the thermodynamic equilibrium at the desired concentration and temperature. Since the snow layer bottom is quickly cooled by maintaining a fixed cooling wall temperature, the aqueous solution in the snow layer will freeze gradually upwards without natural convection in the layer due to the stable density distribution. It is seen that the temperature/concentration and the freezing volume fraction are affected by the cooling wall temperature and the initial concentration in the layer. A simple idealized numerical model predicts well the freezing behavior of the snow layer saturated with the aqueous solution.

  10. Calcium and ascorbic acid affect cellular structure and water mobility in apple tissue during osmotic dehydration in sucrose solutions.

    PubMed

    Mauro, Maria A; Dellarosa, Nicolò; Tylewicz, Urszula; Tappi, Silvia; Laghi, Luca; Rocculi, Pietro; Rosa, Marco Dalla

    2016-03-15

    The effects of the addition of calcium lactate and ascorbic acid to sucrose osmotic solutions on cell viability and microstructure of apple tissue were studied. In addition, water distribution and mobility modification of the different cellular compartments were observed. Fluorescence microscopy, light microscopy and time domain nuclear magnetic resonance (TD-NMR) were respectively used to evaluate cell viability and microstructural changes during osmotic dehydration. Tissues treated in a sucrose-calcium lactate-ascorbic acid solution did not show viability. Calcium lactate had some effects on cell walls and membranes. Sucrose solution visibly preserved the protoplast viability and slightly influenced the water distribution within the apple tissue, as highlighted by TD-NMR, which showed higher proton intensity in the vacuoles and lower intensity in cytoplasm-free spaces compared to other treatments. The presence of ascorbic acid enhanced calcium impregnation, which was associated with permeability changes of the cellular wall and membranes. PMID:26575708