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The evaluation of nano-priming effect with galactomannan stabilized Phyto-complexed calcium hydroxide (Ca(OH)2), selenium oxyanion‑calcium hydroxide SeO-(Ca(OH)2), and selenium‑calcium hydroxide Se-(Ca(OH)2) nanocomposites was carried out in Vigna radiata (Green gram) seeds. The green source Cassia angustifolia seed rich in galactomannan and other phytoconstituents was detected experimentally and characterized with GC–MS, UV, FT-IR, NMR, XRD, and SEM studies. The highly active galactomannan and other biomolecules, enable their terminal oxygen and hydroxide groups to bind with calcium and selenium ions through bidentate and monodentate chelation, followed by bio-reduction. On the mild-thermal agitation, bio-stabilized (Ca(OH)2), SeO-(Ca(OH)2), and Se-(Ca(OH)2) nanocomposite coated with seed-derived biomolecules were precipitated under an alkaline condition. The size and morphological parameters of bio-fabricated nanocomposites were characterized to exhibit the spherical and hexagonal shape in nanoscale images of size 17.9 nm for (Ca(OH)2), 56.2 nm for SeO-(Ca(OH)2), and 69.3 nm Se-(Ca(OH)2). The sub-standard seed lot of Vigna radiata (Green gram) seeds (71%) was examined using synthesized nanocomposites at various concentrations, and the obtained physiological parameters in seedlings were compared with hydro-primed seeds. The nano-priming action of all the Phyto-complexed nanocomposites was predicted with a positive response, where the porous Se-(Ca(OH)2) possess high efficacy interaction on seed embryos and beneficially results at 90% germination.

Calcium hydroxide nanoparticles dispersed in ethanol or 2-propanol have been proposed for deacidification treatments of cellulose-based supports and are currently adopted by many paper and painting...

The development of inexpensive and environmentally friendly graphene-like carbon is critical for its integration into industrial products. This work highlights the production of graphene-like carbon structures from calcium hydroxide. The chemical vapor deposition conditions to grow graphitic carbon on a calcium hydroxide catalyst are reported. Acetylene, steam, and calcium hydroxide are used to grow a crumpled carbon morphology. The crumpled carbon resulted in a high surface area of 1276 m2/g and high electrical conductivity (>105 S/m). Additionally, the significance and origin of the C 1s X-ray photoelectron spectroscopy (XPS) π–π* plasmon loss peak as it is related to high electrical conductivity is reported. A unique mechanism for the catalytic process involving calcium acetylide is proposed. Several deposition times, steam concentration, and catalyst morphology were tested to synthesize a variety of carbon morphologies from calcium-based materials. Crumpled carbon, hollow nanospheres, bamboo-like carbon nanotubes, multi-walled carbon nanotubes, and graphene fiber morphologies were all formed using calcium-based catalysts. Multiple reaction conditions, a scaled reaction (300 g), and catalyst recyclability were investigated. Calcium-based materials were then used as catalysts for the growth of other graphene-like carbons.

The accelerated chemical-industry has caused a rapid increase of calcium-containing alkali wastes, containing a large amount of calcium, magnesium, aluminum, and iron ions and caused a great risk to environment. Anaerobic digestion or dark fermentation is one of the most promising technologies to recover biogas, such as methane and hydrogen. Nevertheless, the hydrolysis processes of lignocellulosic biomass and waste activated sludge were the rate-limiting step of the biochemical reactions, which focused on pretreatment to improve the biodegradability of substrate. In addition, when some easily acidified wastes, such as kitchen residue, fruit and vegetable waste, and high concentration organic wastewater, are used as substrate to produce hydrogen and methane, volatile fatty acid accumulation often occurs, causing the process instability. Thus, this paper reviewed the main roles of calcium-based alkali materials such as calcium oxide, calcium peroxide and calcium hydroxide on the substrate pretreatment for obtaining high biodegradability, while others (e.g. calcium carbonate, lime and red muds) used as additives for maintaining process stability, thereby increasing biogas yield from anaerobic digestion and dark fermentation.

Over 200 million people in over 35 countries are affected by excessive fluoride in their waters. For people that do not have access to a centralized water treatment plant, there is a need for an on-site defluoridation system that requires no special operational expertise, does not use hazardous chemicals, and is sustainable by the local population. 8 different calcium phosphate precipitation systems were analyzed and tested for fluoride removal effectiveness. An effective system would have final fluoride concentrations less than 1.5 mg/L and final solutions with pH within drinkable limits. Phosphoric acid with the addition of a calcium carbonate source was found to have a 99.8% fluoride removal rate. Monosodium phosphate with addition of slaked lime was also found to be effective with a 99.98% fluoride removal rate. An optimal slaked lime to monosodium phosphate ratio that achieved effective fluoride removal and neutral pH was found. With 0.45 g of Ca(OH)2 and 1 g of NaH2PO4, initial fluoride concentrations up to 100 mg/L or more could be reduced to near zero concentrations, and a volume of approximately 337 mL of water with a concentration of 5 mg/L F- could to be reduced to less than 1.5 mg/L F-.

This research work presents an optimum setting at which the production of calcium citrate malate would have the highest yield. The factors that were varied are temperature and the concentrations of citric acid and malic acid. Duck eggshells were used as the source of calcium. The temperature settings were at room temperature (25°C) and at 80°C, the concentrations of citric acid at 1.5 M and 1.7 M and that of malic acid at 2.2 M and at 2.5 M. Using 23 factorial design of experiment (8 settings), the main effects and the interaction effects were plotted to derive an empirical model to predict the yield of calcium citrate malate. Furthermore, a comparison of x-ray diffraction graphs was conducted to evaluate the final product.

In this study, lime (calcium hydroxide) treatment (LT) was applied as an alkaline pretreatment subsequent to hydrothermal treatment (HT) in terms of fermentable sugar and bioethanol production from acacia wood. To maximize the hydrolysis of cellulose and hemicellulose, the condition of 200 °C for 10 min of HT was selected for subsequent lime treatment. The optimum conditions of LT were established to be a ratio of calcium hydroxide to hydrothermally treated acacia biomass of 12.2%, temperature of 70.9 °C, and reaction time of 23.5 h using a response surface methodology, and the maximum glucose yield by prediction and experiment were determined to be 74.4% and 73.5%, respectively. Further mechanical refining accelerated the access of the enzyme to glucan, resulting in an increase in glucose conversion (80.5%). Although the glucose yield by LT was 21.5% higher than that of HT, the ethanol yield was 33.5% lower due to the negative effect of residual calcium ions on yeast fermentation.

O objetivo deste trabalho é verificar a capacidade do hidróxido de cálcio em manter o canal asséptico após a realização do preparo químico-mecânico em dentes com necrose pulpar e presença de lesão periapical. Nestas condições, foram selecionados 19 pacientes e realizado teste bacteriológico durante o tratamento endodôntico. Dentes com culturas negativas após o prepara químico-mecânico, 80% mantiveram-se negativos após a remoção do hidróxido de cálcio utilizado como medicação de demora, e 100% negativo após uso do PMCC. Dessa forma nota-se que o PMCC, assim como o hidróxido de cálcio, manteve a desinfeção obtida durante o prepara químico-mecânico, podendo ser utilizado como medicação intracanal em dentes com polpa necrosada. The purpose of this study is to evaluate calcium hydroxide as a root canal dressing in presence of a picai lesion due to pulpal necrosis, after chemomechanical preparation. Culture test were done in 19 patients in wich 80% of ali teeth treated with calcium hydroxide remained negative and 100% treated with PMCC. Under the present experimental conditions, PMCC as well as calcium hydroxide mantained the desinfection status pursued during chemomechanical preparation and therefore is indicated as an intracanal medicament in such cases.

Magnesium oxide (MgO) nanoparticles have been widely used in a variety of applications because of their good surface reactivity. Magnesium oxide from bittern has a larger surface area compared to magnesium oxide from calcined magnesite and magnesium ions precipitation from bittern using sodium hydroxide has higher purity than using calcium hydroxide or ammonium hydroxide. In this research, sodium hydroxide was added to a bittern solution obtaining magnesium hydroxide precipitate, followed by the calcination process to produce magnesium oxide. Nano magnesium oxide was synthesized by the ultrasonic destruction process using ethanol and 2-propanol as media. In this study, sonication time and particle concentration effect on the ultrasonic destruction process were investigated. During the process, the sonication time was varied between 8, 16, 32, 64, and 128 minutes while the magnesium oxide concentration was varied between 1 %, 2 %, and 3 %. Increasing sonication time and particle concentration will decrease the particle size. The previous study shows that particles with very small sizes tend to have an agglomeration effect. The aim of this work is to optimize nano magnesium oxide production from bittern. Surfactant addition was also studied to prevent agglomeration between particles. Four types of surfactant namely anionic (sodium lauryl sulfate), cationic (cetyl tri-methyl-ammonium bromide), amphoteric (fatty acid amido alkyl betaine), and non-ionic (nonylphenol 10 ethoxylated) with a concentration of 1 % and a volume of 0.125 ml were added during the second ultrasonic destruction process. All types of surfactants have a positive effect to prevent agglomeration during the ultrasonic destruction process, with the amphoteric surfactant having the highest performance, Наночастицы оксида магния (MgO) широко используются в различных областях благодаря высокой поверхностной реакционной способности. Оксид магния из соляного раствора имеет большую площадь поверхности по сравнению с оксидом магния из кальцинированного магнезита, а осаждение ионов магния из соляного раствора с использованием гидроксида натрия имеет более высокую чистоту, чем при использовании гидроксида кальция или гидроксида аммония. В данном исследовании для получения оксида магния гидроксид натрия добавляли в соляной раствор для осаждения гидроксида магния с последующим прокаливанием. Нанооксид магния синтезировали методом ультразвуковой деструкции с использованием сред этанола и 2-пропанола. В данной работе было исследовано влияние времени ультразвуковой обработки и концентрации частиц на процесс ультразвуковой деструкции. Во время процесса время ультразвуковой обработки варьировалось в пределах 8, 16, 32, 64 и 128 минут, концентрация оксида магния – 1 %, 2 % и 3 %. Увеличение времени ультразвуковой обработки и концентрации частиц приводит к уменьшению размера частиц. Предыдущее исследование показало, что частицы очень малого размера имеют тенденцию к агломерации. Целью данной работы является оптимизация производства нанооксида магния из соляного раствора. Также изучали добавление поверхностно-активных веществ для предотвращения агломерации частиц. Во время второго процесса ультразвуковой деструкции добавляли четыре типа поверхностно-активных веществ: анионное (лаурилсульфат натрия), катионное (цетримониум бромид), амфотерное (амидоалкилбетаин жирных кислот) и неионное (этоксилированный нонилфенол 10) с концентрацией 1 % и объемом 0,125 мл. Все типы поверхностно-активных веществ оказывают положительное влияние на предотвращение агломерации в процессе ультразвуковой деструкции, причем амфотерное поверхностно-активное вещество обладает самой высокой эффективностью, Наночастки оксиду магнію (MgO) широко використовуються в різних областях завдяки високій поверхневій реакційній здатності. Оксид магнію з соляного розчину має більшу площу поверхні в порівнянні з оксидом магнію з кальцинованого магнезиту, а осадження іонів магнію з соляного розчину з використанням гідроксиду натрію має більш високу чистоту, ніж при використанні гідроксиду кальцію або гідроксиду амонію. У даному дослідженні для отримання оксиду магнію гідроксид натрію додавали в соляний розчин для осадження гідроксиду магнію з подальшим прожарюванням. Нанооксид магнію синтезували методом ультразвукової деструкції з використанням середовищ етанолу і 2-пропанолу. У даній роботі було досліджено вплив часу ультразвукової обробки і концентрації часток на процес ультразвукової деструкції. Під час процесу час ультразвукової обробки варіювався в межах 8, 16, 32, 64 і 128 хвилин, концентрація оксиду магнію – 1 %, 2 % і 3 %. Збільшення часу ультразвукової обробки і концентрації часток призводить до зменшення розміру часток. Попереднє дослідження показало, що частки дуже малого розміру мають тенденцію до агломерації. Метою даної роботи є оптимізація виробництва нанооксиду магнію з соляного розчину. Також вивчали додавання поверхнево-активних речовин для запобігання агломерації часток. Під час другого процесу ультразвукової деструкції додавали чотири типи поверхнево-активних речовин: аніонну (лаурилсульфат натрію), катіонну (цетримоніум бромід), амфотерну (амідоалкілбетаїн жирних кислот) і неіонну (етоксильований нонілфенол 10) з концентрацією 1 % і об'ємом 0,125 мл. Всі типи поверхнево-активних речовин чинять позитивний вплив на запобігання агломерації в процесі ультразвукової деструкції, причому амфотерна поверхнево-активна речовина володіє найвищою ефективністю

Thermally-induced reaction between liquid sodium (Na(l)) and calcium hydroxide (Ca(OH)2(s)) was investigated as one of the possible component reactions when Na(l) was reacted with concrete materials under a postulated severe accidental condition in a sodium-cooled fast reactor. The Na(l)–Ca(OH)2(s) reaction was traced using a differential scanning calorimetry (DSC), placed in an argon substituted glove box. An exothermic DSC peak appeared in the temperature range of 550–700 K was attributed to the Na(l)–Ca(OH)2(s) reaction to form a mixed phase comprised of calcium oxide (CaO(s)), sodium hydroxide (NaOH(s,l)) and sodium oxide (Na2O(s)). Based on morphological analyses of reacting system, a physico-geometrical reaction model was proposed: the reaction initiates at the initial contact area of Na(l) and Ca(OH)2(s) and proceeds by the movement of the reaction interface toward Ca(OH)2(s), where the product layer is composed of CaO(s), NaOH(s,l), and Na2O(s). Therefore, the Na(l) diffusion through the product layer is the necessary process to promote the reaction between Na(l) and Ca(OH)2(s), for which a significant influence of the melting of NaOH(s) that has on the overall kinetic behavior is expected. This melting occurs midway through the Na(l)–Ca(OH)2(s) reaction at 594 K. The overall Na(l)–Ca(OH)2(s) reaction was analyzed kinetically using the DSC curves recorded at different heating rates. A partially overlapping two-step reaction feature was evidenced, in which the primary and secondary reaction steps were characterized by the apparent activation energy values of 128 and 138 kJ mol−1, respectively. The multistep feature of the Na(l)–Ca(OH)2(s) reaction could result from the melting of NaOH(s) in the product layer.

Many SCR catalysts without V species are developed and used for the NO abatement. The content of Ca in the real flue gas will result in the deactivation of catalysts. In this work, the effect of Ca(OH)2 on the denitration performance of the Fe–Ce/TiO2 catalyst for SCR reaction was explored. The BET, XRD, XPS, NH3-TPD, Py-IR, UV–Vis DRS, H2-TPR, and SEM–EDS mapping techniques were used to characterize the evolution of active species and the surface properties over the studied catalysts. The gained results demonstrate that the Ca(OH)2 results in serious deactivation of Fe–Ce/TiO2 catalyst for NH3-SCR reaction and the degree of deactivation is closely related to the loading of Ca(OH)2. Such serious deactivation caused by Ca(OH)2 is attributed to the smaller surface area, the declined redox ability and surface acidity, the lower content of Ce3+ and Fe3+, as well as the less surface adsorbed oxygen species. Moreover, the addition of Ca(OH)2 leads to poor dispersion of Ce and Fe species over the catalyst surface, which may also be responsible for the fall of the catalytic performance of the catalyst.

Objectives: This study compared the clinical and radiographic effects of two medicaments. Subjects and Methods: Endodontic treatment was performed on 26 pulpally involved primary molars in 4 to 7 years old children suffering from badly decayed or carious primary teeth which indicated for root canal treatment. Two medicaments (3Mix and ZOE) on the pulpectomized teeth comprised 2 main groups. The root canals were obturated with zinc oxide eugenol mix in the first group and a mixture of calcium hydroxide, zinc oxide, and 10% sodium fluoride solution in the second group , using hand-operated lentulo-spirals. The teeth were evaluated clinically and radiographically at different intervals (3 months,6 months, 12 months). Results: In the first group, pulpectomy with zinc oxide eugenol gave raise a 92.3% success rate, while the second group with triple antibiotic paste was 84.6%.Conclusion: Shows that ZnOE offers good clinical and radiographical results when compared with Tiple mix paste but with no statistically significant differences.

Livestock farming is affected by the occurrence of infectious diseases, but outbreaks can be prevented by proper sanitary control measures. Calcium hydroxide (Ca(OH)2), commonly called slaked lime, powder is traditionally used as a disinfectant to prevent infectious diseases in livestock. Since Ca(OH)2 can inactivate a wide variety of pathogens, has a small environmental impact, does not require a disinfection tank (i.e., can be spread directly on the ground) and is produced inexpensively worldwide, it is used for the prevention of epidemics on farms worldwide. Water is essential for the strong alkalinity that underlies its disinfecting effect, but it is unknown how much water is required under field conditions. In addition, Ca(OH)2 reacts with carbon dioxide in the environment, reducing its pH, but it is unclear how long its degradation takes under actual field use. Thus, we measured the water adsorption ability of Ca(OH)2-based disinfectants and its relation to disinfectant activity, as assessed by colony counts and live/dead staining and observation. We found that 15–20% (w/w) water in Ca(OH)2 was necessary for disinfection to occur in practice. Moreover, we found that the pH of Ca(OH)2 decreased within about two weeks to one month under actual use in practical conditions and lost its ability to disinfect. We further showed that granules prepared from Ca(OH)2 and zeolite maintained high alkalinity more than twice as long as calcium powder. These findings will help to establish a suitable method of applying Ca(OH)2 to protect farms from infectious diseases.

This study reports a facile method to synthesize the calcium silicate-based cement with an enhanced radiopacifying performance. Sr-substituted Ca3SiO5 (Ca3−xSrxSiO5, x = 0.0 ~ 0.2) was prepared by solid-state reaction, and its phase, hydration behavior, and radiopacity were investigated and compared with those of 10 wt% Bi2O3-added Ca3SiO5. A nearly single-phase Ca3SiO5 was synthesized at 1400 °C and the solubility limit of Sr into Ca3SiO5 was approximately 3.3 mol % (x = 0.1). The Sr substitution did not affect the size and morphology of Ca3SiO5 powder. The extent of hydration was slightly delayed in Sr-substituted Ca3SiO5, but the hydration products were the same composing of fiber-like calcium silicate hydrate (C–S–H) and plate-like calcium hydroxide (Ca(OH)2). The radiopacity of Ca3SiO5 was significantly enhanced with Sr substitution and it was slightly higher than that of Bi2O3-added Ca3SiO5 at a similar concentration. Consequently, Sr-substituted Ca3SiO5 can be a promising dental root canal filling material with an improved radiopacifying property.

In this work, optimal and waste-free technologies were proposed for the production of nanocrystalline cellulose (NCC) and its composites with inorganic pigment, as well as semi-finished products containing aggregates of nanoparticles. The following optimal hydrolysis conditions were found: concentration of sulfuric acid 40 wt%, temperature 80°C, duration 1 h, acid/cellulose ratio 7. After hydrolysis stage, the hydrolyzed cellulose was washed, diluted with water and disintegrated to isolate individual nanoparticles. Then, the diluted NCC dispersion was evaporated to obtain a commercial product - concentrated NCC paste. In order to obtain a composite, the acid in the unwashed hydrolyzed cellulose was neutralized with calcium hydroxide to precipitate a white pigment, calcium sulfate. In addition, the spent acid and acidic washings were collected and treated with hydroxylapatite (HAP) to produce a valuable by-product, superphosphate (SUP), the sale of which significantly reduces the cost of the primary product, NCC. Contaminated water collected after washing, neutralization and evaporation was purified and returned to the technological cycle. To reduce the cost of production, such expensive process steps as disintegration and evaporation of diluted dispersion were eliminated, which made it possible to obtain cheap semi-finished products containing NCC aggregates or composite of NCC with inorganic calcium sulfate particles.

This work aims to investigate the coexistence of the poly(phospho-siloxo) networks and calcium phosphates on the compressive strengths of the acid-based geopolymers obtained at room temperature. Waste fired brick and phosphoric acid were used as an aluminosilicate and chemical reagent, respectively. Calcium aluminate hydrate was prepared by mixing calcium hydroxide from the calcined eggshell and calcined bauxite. Calcium silicate hydrate was obtained by the mixture of rice husk ash and calcium hydroxide. The molar ratios CaO/Al2O3 and CaO/SiO2 in the calcium aluminate and calcium silicate hydrates are equals to 1.0. The X-ray patterns of the acid-based geopolymers indicate the broad hump structure between 18 and 38°(2θ). In addition to this broad band, those from the mixture of calcium sources show the reflection peaks of monetite and brushite. The compressive strength of the reference is 56.43 MPa. Those obtained with the addition of 10, 20, 40 and 50 g of calcined eggshell are 30.15, 22.85, 21.16 and 13.47 MPa, respectively. The ones from calcium aluminate hydrate are 32.62, 31.58, 17.83 and 16.33 MPa, respectively. Whereas those containing calcium silicate hydrate are 44.02, 42.71, 40.19 and 18.59 MPa, respectively. This work demonstrates that the formation of calcium phosphates in the structure of the acid-based geopolymers decreases the poly(phospho-siloxo) chains and therefore reduces their compressive strengths. The moderate addition of calcium silicate hydrate reduces slightly the compressive strengths of the acid-based geopolymers which can be comparable to the one of CEM II 42.5R.

Palm oil boiler ash is the waste from the palm oil boiler combustion which contains a lot of silicates. In addition, palm oil boiler ash also contains inorganic cations such as potassium and sodium. Palm oil boiler ash is pozzolanic material, which is a non-binding material such as cement, but contains active Silica Oxide (SiO2) compounds which when reacted with free lime or calcium hydroxide (Ca (OH2)) and water will form materials such as cement, namely calcium Silica Hydrate. In this study, we will use palm oil boiler ash waste which has been stated to have good soil improvement results as a mixture of peat soil improvement in the hope of getting better improvement results from previous studies in terms of California Bearing Ratio values. The boiler ash to be used is a variation of the mixture of 0%, 5%, 10% and 15% to the weight of the soil sample and using 28 days treatment. The California Bearing Ratio value of the original peat soil is 0.247%, the percentage of 5% increases to 0.433%, at the percentage of 10% is 0.629% and at the percentage of 15% is 0,729%.

The aim of this paper is as follows: (I) determination of physical and chemical characteristics of the wine; (II) determination of the possibility of neutralizing and improving the characteristics of oxidized wines. Two types of wine (red and white) of the individual manufacturer from at south from river Ibar in the territory of Kosovo and Metohia were analyzed. Experimentally determined physico-chemical characteristics are density and quantity of the following: alcohol; extract; reducing sugars; ash; total acids; volatile acids; total; and free sulfur dioxide. Neutralization of oxidized wines (reduction of quantity of volatile acids) was carried out using chemical reagents (sodium hydrogen carbonate, calcium carbonate, calcium oxide, calcium hydroxide) and biological material (corn flour). By using sodium hydrogen carbonate to neutralize oxidized wines, the amount of volatile acids is reduced by 57% in red wine and 54.6% in white. By using corn flour, the content of volatile acids in red wine is reduced by 56% and in white by 54%, which is confirmed by the traditional experience of application of corn pistes during distillation. The methods of classical analytical chemistry were used to perform the experimental part of this paper.

Decontamination of pathogens on surfaces of substances is very important for controlling infectious diseases. In the present experiments, we tested various disinfectants in aqueous phase as well as on plastic surface carrying a viral inoculum, through dropping and wiping decontamination techniques, comparatively, so as to evaluate virucidal efficacies of those disinfectants toward an avian coronavirus (infectious bronchitis virus: IBV). We regard this evaluation system applicable to SARS-CoV-2. The disinfectants evaluated were 0.17% food additive glade calcium hydroxide (FdCa(OH)2) solution, sodium hypochlorite at 500 or 1,000 ppm of total chlorine (NaClO-500 or NaClO-1,000, respectively), NaClO at 500 ppm of total chlorine in 0.17% FdCa(OH)2 (Mix-500) and quaternary ammonium compound (QAC) diluted 500-fold in water (QAC-500). In the suspension test, all solutions inactivated IBV inoculum that contained 5% fetal bovine serum (FBS) under detectable level within 30 sec. In the carrier test, all solutions, except NaClO-500, could inactivate IBV with 0.5% FBS on a carrier to undetectable level in the wiping-sheets and wiped-carriers. We thus conclude that suspension and carrier tests should be introduced to evaluate disinfectants for the field usage, and that this evaluation system is important and workable for resultful selection of the tested disinfectants against avian coronavirus and SARS-CoV-2 on surfaces, particularly on plastic fomite.

Objective of this study is to evaluate clinically and radiographically the calcium – hydroxide formocresol mix as a root filling material in primary teeth . Materials & Methods: The study was performed on 75 primary molars of patients aged from 4-8 years that indicated for pulpectomy. The teeth were divided randomly into 3 main equal groups. Each group formed of 25 primary molars. Group A: 25 children teeth in which zinc oxide and eugenol (ZO/E) was used as filling material . Group B: 25 children teeth in which calcium hydroxide formocresol mix was used as a filling material. Group C : 25 children teeth In which matapex was used as filling material . The teeth were assessed clinically and radiographically at 5 different intervals (preoperative, 24 hours, 6 weeks , 3 months and 6 month postoperative), using standard clinical and radiographic criteria. Results: It was found that Maetapex offers best clinical and radiographical results when compared with ZO/E and calcium hydroxide fromocresol mix . ZO/E (group A) showed (84%) success rate, while the Calcuim hydroxide fromocresol mix (group B) showed a higher success rate (88%) than (ZO/E) . Metapex (group c) show best success rate of all groups (94%) while failure rate showed (16%) , (12% ) and (6%) respectively. Conclusion: Metapex is the best material as root filling material with a high success rate and showing competitive properties to ZO/E and Calcium hydroxide formocresol mix . calcium hydroxide formocresol mix shows better result than ZO/E .

Precipitation of calcium deficient hydroxyapatite nanoparticles in an environmentally benign manner by using only dilute solutions of calcium hydroxide and phosphoric acid without pH adjustment and addition of other chemicals, and water, being the only by-product was investigated by using continuous flow Vortex Reactor (VR) and Semi-Batch Reactor (SBR). The effect of hydrodynamics by changing the Reynolds number of the jets providing residence times of 8.4 ms to 4.37 s for VR, and by changing the stirrer speed between 100 rpm (Re = 2656) and 1000 rpm (Re = 26560) for SBR, on the particle size, particle size distribution, and morphology of the particles was investigated for both systems. It has been shown that it is possible to produce pure phase hydroxyapatite nanoparticles in the desired morphology by changing production system, without resorting to additives. While VR produced rod-like particles with the crystallite size around 4 nm, SBR produced spherical particles with the crystallite size of around 5 nm.

The purpose of this study was to evaluate the cleanliness of root canal walls and dentinal tubules after attempting to remove the calcium hydroxide dressing with different irrigant solutions and the use of nonactivated irrigation or passive ultrasonic irrigation (PUI).After root canal instrumentation, 80 single-rooted teeth were filled with calcium hydroxide mixed with propylene glycol and 0.1% rhodamine B dye and inserted into canals with a Lentulo spiral. The calcium hydroxide dressing was initially removed with 10 mL saline solution and reinstrumentation with the master apical file. Then, the samples were randomly assigned into 8 experimental groups (n = 10) according to the irrigant solution with or without PUI: 2.5% sodium hypochlorite, 17% ethylenediaminetetraacetic acid + 1.25% sodium lauryl ether sulfate (EDTA-T), 37% phosphoric acid, or 70% ethanol. A final flush with 5 mL saline solution was performed. The percentage of clean root canal walls and the depth of clean dentinal tubules were measured with images of confocal laser scanning microscopy. The groups were compared using the 2-way analysis of variance test with the Bonferroni post hoc test for depth analysis and the Kruskal-Wallis with Dunn post hoc test for the perimeter analysis.Irrigation with 70% ethanol presented a significantly higher percentage of clean root canal walls and a higher depth of clean dentinal tubules when compared with irrigation with 2.5% sodium hypochlorite and 17% EDTA-T for both irrigation methods (P.05). No differences were observed between nonactivated irrigation or PUI protocols (P.05).Seventy percent ethanol enhanced calcium hydroxide removal from the apical root third compared with 2.5% sodium hypochlorite or 17% EDTA-T.

The extract of Myracrodruon urundeuva Allemao (aroeira), as a vehicle, associated with calcium hydroxide (CH) paste was evaluated based on cell viability, antimicrobial action, calcium ion release, and pH variation. Calcium hydroxide with propylene glycol was used as control. The pH variation was measured at 3, 24, 72, 168, 140, 360, and 720 h and calcium ion release was measured on days 7, 15, and 30. Cell viability was assessed with NIH/3T3 cells using MTT and crystal violet assays, after 24, 48, and 72 h. Antibacterial activity was determined by the disc diffusion method, while microbial reduction (Enterococcus faecalis) was evaluated using the time-kill test. The CH paste formulated with aroeira showed antibacterial activity against Enterococcus faecalis and further did not interfere with pH, calcium ion release, or cell viability; moreover, the formulation had antimicrobial activity and could serve as a vehicle for CH paste.

The aim of this article was to investigate the unknown radiopacity performances of OrthoMTA and RetroMTA via means of a contemporary image analyzing methods and energy dispersive X-ray spectroscopy. Three commercial hydraulic calcium silicate-based cements and a calcium hydroxide-based paste were used. Pure-grade zirconium oxide, bismuth oxide, zinc oxide, barium sulfate, and calcium hydroxide were as references. An energy-dispersive X-ray spectroscopy instrument was used for the elemental analysis. Radiographic image data was obtained according to the International Organization for Standardization 6876-2012 specifications. The region of interest was determined for each specimen. Mean (±SD) grey values of the X-ray image data was measured with an image analyzing software. The calibration curve was created by curve-plotting software and the mean grey-values were matched versus Al values (mm Al). Data were analyzed with one-way ANOVA followed by Tukey's multiple comparison test. Spectroscopic characterization of the commercial materials was shown with assigned Carbon, oxygen, aluminum, silicon, calcium, zinc, zirconium, barium, tungsten, bismuth, and sulfur elements. The major radiopacifier/s of OrthoMTA is Bi, of RetroMTA is Zr, of BioDentine are Ba and Zr, and of ProCal is Ba. The radiopacity values of all commercial materials are significantly different (p .05). The rank of the radiopacity values: RetroMTA (3.36 ± 0.29mmAl) OrthoMTA (2.56 ± 0.19mmAl) BioDentine (2.02 ± 0.12mmAl) ProCal (1.46 ± 0.60mmAl). The study reported that the radiopacity values and spectral characterization of RetroMTA and OrthoMTA cements. The pixel-based and reproducible method could be used universally to the quantification of the radiodensity of digitally collected X-ray data.

La elevada incidencia del Enterococcus faecalis en procedimientos odontológicos es un tópico de interés para el área de la salud, esta bacteria resiste a varios antimicrobianos y su proliferación aumenta debido a su baja susceptibilidad a sustancias de uso convencional como el hidróxido de calcio, convirtiéndose en una de las principales causas del fracaso de los tratamientos de conducto. La presente investigación evaluó la susceptibilidad in vitro del Enterococcus faecalis cepa ATCC-29212 frente a la combinación de sustancias y antibióticos con el hidróxido de calcio. Se utilizó la técnica de difusión en agar, inoculando el microorganismo en cajas de Petri con agar Cerebro Corazón (BHI), tratado con discos de papel filtro impregnados con 1µl de cada tratamiento por triplicado; T1 (Hidróxido de Calcio + propilenglicol), T2 (Hidróxido de Calcio + paramonoclorofenol), T3 (Hidróxido de Calcio + ampicilina gentamicina + propilenglicol), T4 (Hidróxido de Calcio + Solución Salina Fisiológica), Control positivo (medicamento comercial a base de Hidróxido de Calcio), se incubó a 35°C durante 24h, los halos formados alrededor de cada disco fueron medidos y comparados con la escala de Duraffourd y procesados mediante ANOVA de un factor. Se obtuvo una medida del halo de inhibición de 22,50±3,3 mm, con el tratamiento T3, siendo sumamente sensible. Concluyendo que este resultó el más efectivo en comparación el resto de las pruebas in vitro en comparación con el resto de los fármacos investigados.

Isoconversional methods combined with thermogravimetry were applied to investigate the decomposition kinetics of bastnaesite concentrates with different amounts of calcium hydroxide added. The apparent activation energy was calculated, and the results indicate that the overall reaction involves more than one single step. The reaction with a lower content ( 15 wt%) involves another step which denotes the decomposition of newly formed calcium carbonate during roasting. The activation energy increases with increasing amount of calcium hydroxide in the lower range (0–15 wt%). This is due to the resistance of calcium hydroxide to heat and mass transport. However, more calcium can promote the decomposition reaction more effectively and thus reduce the activation energy. Nonlinear fitting was performed by fitting the experimental data to Avrami-Erofeev model to determine the reaction model and pre-exponential factor. The theoretical models were proven to be reliable for kinetic prediction.

The hydrothermal dissolution of a Brazilian glauconitic siltstone, known as Verdete, in the presence of calcium hydroxide was studied using conventional and rotary furnaces. The objective was to as...

The purpose of this study was to compare to evaluate the post operative pain with different calcium hydroxide formulations when used as intracanal medicament in root canal which was evaluated by VAS scale. Materials and Methods: The 150 subjects were randomly assigned to four groups and one control group depending upon the intracanal medicament: Group 1: Calcium hydroxide paste (Ivoclar) was used as intracanal medicament, Group 2: Calcium hydroxide paste with iodoform (Metapex) was used as intracanal medicament, Group 3: Calcium hydroxide points (Hygenic) was used as intracanal medicament, Group 4: Calcium hydroxide paste using chitosan (0.2%) as vehicle was used as intracanal medicament, Group 5: Control group containing dry sterile cotton. The incidence and intensity of preoperative pain and experienced post operative pain (on 6th, 12th, 24th hour and 48th hour) after first visit of treatment were assessed according to patient’s recordings in visual analogue scale. Results: The medicament causing least operative pain are ranked according to superiority as Calcium hydroxide paste > Calcium hydroxide points > Calcium hydroxide with chitosan > calcium hydroxide with iodoform Conclusion: At 6th postoperative hour, least post operative pain was recorded by the calcium hydroxide points and high post operative pain in calcium hydroxide with iodine (Metapex). At 12th, 24th, 48th postoperative hour least post operative pain was recorded by calcium hydroxide paste (Apexcal). Keywords: Calcium hydroxide medicament, Calcium hydroxide points.

CO2 absorbents were introduced into anesthesia practice in 1924 and are essential when using a circle system to minimize waste by reducing fresh gas flow to allow exhaled anesthetic agents to be rebreathed. For many years, absorbent formulations consisted of calcium hydroxide combined with strong bases like sodium and potassium hydroxide. When Sevoflurane and Desflurane were introduced, the potential for toxicity (compound A and CO, respectively) due to the interaction of these agents with absorbents became apparent. Studies demonstrated that strong bases added to calcium hydroxide were the cause of the toxicity, but that by eliminating potassium hydroxide and reducing the concentration of sodium hydroxide to

The production of soda ash by the Solvay method is accompanied by the formation of wastewater, much of which is the distiller liquid containing up to 100 g/L calcium chloride and up to 50 g/L sodium chloride. A highly efficient electrochemical method was proposed to treat the distiller liquid to form calcium hydroxide, sodium hydroxide, and hydrochloric acid. The proposed process consists of two stages. At the first stage, the distiller liquid is treated with alkali to produce calcium hydroxide and a filtrate containing sodium chloride. At the second stage, the filtrate is processed in a membrane electrolyzer to obtain solutions of sodium hydroxide and hydrochloric acid. It was shown that the process of treating the distiller liquid with alkali should be carried out at a CaCl2 : NaOH molar ratio of 1 : 1.25. The processing of the filtrate in the membrane electrolyzer makes it possible to obtain sodium hydroxide at a concentration of up to 4320 g/L and hydrochloric acid at a concentration of 148 g/L.

Made available in DSpace on 2021-06-25T10:35:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-09-01 Aim: The aim of this study to evaluate the effects of 10% alpha-tocopherol (10AT) or 20% alpha-tocopherol (20AT) incorporation on biological compatibility, pH, and calcium release of calcium hydroxide (CH) paste associated with 2% chlorhexidine digluconate (CHX). Materials and Methods: Four groups were evaluated: CH, CH-CHX, CH-CHX-10AT, and CH-CHX-20AT. For biological compatibility test, polyethylene tubes containing several pastes were implanted in Wistar rats' subcutaneous tissue (n = 28). After 48 h and 7, 14, and 21 days postimplantation, the specimens were removed and subjected to histologic and histomorphometric analysis. The number of inflammatory cells was evaluated. For pH and calcium release analysis, the pastes were placed individually (n = 10) in plastic tubes and immersed in deionized water. The calcium release and pH changes were evaluated in 24 and 48 h and 7, 14, and 21 days. All data were submitted to Kruskal-Wallis test (α = 0.05). Results: Concerning biological compatibility, all materials shown a similar decidual response (P > 0.05). In the first hours, there was as increase in the number of inflammatory cells, inducing an expressive inflammatory response. After 14 days, inflammation reaction decreased and collagen fiber was organized for the tested pastes (P = 0.05). The pH analysis of the groups maintained the same relationship during the different periods evaluated: the CH and CH-CHX groups showed higher values and were similar to each other (P > 0.05), followed by the CH-CHX-10AT and CH-CHX-20 AT groups. Regarding the amount of calcium ions, in the initial (24 hours) and final (21 days) periods, the groups did not present differences between them (P > 0.05). Conclusion: The 10AT or 20AT, as an antioxidant agent, incorporation to CH and 2% CHX paste negatively affected biological and physicochemical properties. Department of Restorative Dentistry School of Dentistry Araraquara Sao Paulo State University - UNESP Department of Basic Sciences Araçatuba Dental School Sao Paulo State University - UNESP Department of Restorative Dentistry School of Dentistry Araraquara Sao Paulo State University - UNESP Department of Basic Sciences Araçatuba Dental School Sao Paulo State University - UNESP

AIM To evaluate the in vitro effect of the novel adhesive monomer CMET, a calcium salt of 4-methacryloxyethyl trimellitate (4-MET), on the proliferation, mineralization and differentiation of odontoblast-like cells, comparing with 4-MET, calcium hydroxide (CH) and mineral trioxide aggregate (MTA). METHODOLOGY Rat odontoblast-like MDPC-23 cells were cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with 5% foetal bovine serum. The powder of four tested materials (CMET, 4-MET, CH and MTA) was first dissolved in distilled water (dH2O) and then was diluted by DMEM to yield final concentrations. Solvent (dH2O) was used as a control. Cell viability was assessed using CCK-8 assay. Real-time RT-PCR was used to quantify the mRNA expression of odontogenic markers, cytokines and integrins. Mineralization inducing capacity was evaluated by alkaline phosphatase (ALPase) activity and alizarin red S staining. Statistical analyses were performed using one-way anova and post hoc Tukey's HSD test, with the significance level at 1%. RESULTS Cell viability was significantly greater in the CMET- (83 to 828 mmol L-1), CH- and MTA-treated (low concentrations) groups than that in the control group (P

The interaction between dacitic tuff and calcium hydroxide under hydrothermal conditions has been investigated. At a ratio of CaO/SiO2 = 0.3–1.5 : 1 and at a ratio between the liquid phase and the solid phase amounting to 10 : 1, after 2 h at 220°C, calcium hydroxide is completely bound. As a result of the destruction of potassium feldspar in tuff, potassium can be transformed into a plant-digestible form.

Concentration of Ca(OH)2 stabilized urine by reverse osmosis (RO) has the potential to cause CaCO3 scaling on the membranes. The aim of this research was to determine whether the addition of carbonate salts could be used to precipitate CaCO3 prior to RO concentration and how to accurately dose the salts. Dosing of NaHCO3 or Na2CO3 reduced the calcium concentration to 11. This is the pH threshold for enzymatic urea hydrolysis in urine, but above the operating pH range of most membranes. However, the pH could be decreased by adding an acid. Measuring conductivity as a proxy for the calcium concentration was found to be an effective method to determine the dose of salt required. Simulations with other carbonate-producing salts (KHCO3, MgCO3, and NH4HCO3) were also shown to be effective. However, NH4HCO3 ($0.53 m−3 urine) was the only other salt comparable in cost to NaHCO3 ($0.49 m−3 urine) and resulted in a final pH within the normal operating range of membranes. The addition of NH4HCO3 would add extra N to the urine rather than sodium ions when dosing NaHCO3. The choice of salt will ultimately depend on what liquid fertilizer composition is desired. HIGHLIGHTS NaHCO3 addition can reduce calcium concentrations in stabilized urine to 0.18 mmol L−1.; NaHCO3 dosing is preferred to Na2CO3 as additional Na+ ions and costs are minimized.; pH is not a good parameter to control NaHCO3 dosing, but conductivity is.; Acid addition or dosing NH4HCO3 can achieve desired pH values.; Additional pre-treatment would increase cost of fertilizer product by 0.13%.

The test method AAR-8 is intended to be used for assessing the potential amount of alkalis released by aggregates in field concrete in the long-term. This is done by measuring the amounts of sodium and potassium ions released from the fine graded (< 4 mm) aggregate immersed in (0.7 M) KOH and NaOH solutions, respectively, at elevated temperature when in contact with excess calcium hydroxide. It is of great importance to realise that this accelerated test method must be considered as a mere indication of potential (maximum) alkali release by the aggregates, rather than a quantification used for the alkali inventory calculations.

The vast amount of carpet waste produced from the manufacturing processes is dumped in landfills, causing environmental issues and problems. In addition to recycling and reuse processes, the conversion of carpet waste into a higher value-added product is an interesting option to manage carpet waste with the most benefits and values. This work highlights the conversion of industrial carpet waste into alternative adsorbents for dye removal. The pre-consumer carpet waste was pyrolyzed at different temperatures ranging from 500 to 900 °C under argon flow. Due to the high fraction of calcium carbonate (CaCO3) filled in the adhesive layer in carpet, CaCO3 was acquired at 500 and 600 °C, while the calcium hydroxide (Ca(OH)2) with a hexagonal platelet-shaped crystal began to form at 700 °C. In addition to CaCO3 and Ca(OH)2, carbon was also found in the samples due to the carbonization of the polymeric fibers and backings. The specific surface area increased with increasing pyrolysis temperature ranging from 15 to 26 m2 g−1 with a predominance of mesopores. Potential utilization as dye adsorbents was evaluated using methylene blue (cationic dye) and methyl orange (anionic dye) at concentrations of 10, 15, and 20 mg L−1. Among all samples, the carpet waste pyrolyzed at 900 °C showed the highest adsorption efficiency of about 100% for methylene blue and 93–99% for methyl orange at the dye concentration of 10–20 mg L−1. The lower adsorption efficiency of methyl orange was due to the effect of electrostatic interaction between the dye molecules and adsorbent surface. The results in this work offer useful information for converting carpet waste into alternative dye adsorbents towards sustainable water management.

Carbon capture and storage (CCS) is an attractive area of research in such fields as CO2 mineral carbonation, global warming and sustainable energy systems. In this study, carbonation efficiency for aqueous mineral carbonation (MC) was achieved through two steps, which include leaching of calcium from cement kiln dust (CKD) followed by the reaction of pure CO2 with the calcium hydroxide precipitates formed by the hydroxylation using NaOH. Response surface methodology (RSM) with a Box-Behnken design (BBD) was applied to optimize the calcium leaching yield, while the carbonation efficiency from CKD was assessed using RSM with central composite design (CCD). Optimization of calcium leaching is highly important, as it is a rate-limiting reaction step in MC and also influences and enhances carbonation efficiency. Different parameters including acid concentration (HNO3), leaching temperature, leaching time, and dose of CKD sample were considered in order to optimize the maximum yield of Ca leaching from the CKD sample. In addition, different CO2 flow rates and temperatures were used as parameters for optimizing carbonation efficiency. Two quadratic regression models were developed for each process, i.e. calcium leaching and carbonation. For calcium leaching, a maximum of 98.55% calcium was extracted under the optimal set of acid concentration 4.13 M, 90 °C, 28 min leaching time, and 13.8 g of CKD sample. For carbonation, the maximum carbonation efficiency of 89.2% was achieved for a CO2 flow rate of 1163 cm3/min at 90 °C. Calcium leaching results indicate that the leaching yield was significantly affected by all the input parameters except leaching time. For carbonation, both factors affected the carbonation efficiency, with the effect temperature shown to be greater than that of the CO2 flow rate. Additionally, the predicted results agreed well with the experimental values for both calcium leaching and carbonation processes, with errors of less than 1% and 5%, respectively.

A study was carried out to investigate the combined effect of released ions in the pulp by pH regulator and mineral surface on dolomite flotation. The tests were carried out using a dolomite sample in a bench flotation cell with automatic froth remover. Zeta potential measurements, solution conductivity and FTIR analysis were done to support the interpretation of the results. The main reagents used for pH adjustment in the alkaline range (calcium hydroxide, sodium hydroxide, and sodium carbonate) were compared using amine or sodium oleate as collector. Dolomite is a sparingly soluble-type calcium mineral (as calcite, apatite, fluorite and scheelite), releasing differ ent amounts of calcium and magnesium ions in the pulp. Amine adsorbs mainly by a chemical complexation mechanism between the molecular specie RNH2 with calcium and magnesium ions present on the dolomite surface. In this system calcium hydroxide must be used because in addition to adjusting the pH it is a calcium ion supplier, thus increasing the collector adsorption. In turn, in the dolomite flotation with oleate, the pH must be regulated with soda ash that precipitates Ca2+ and Mg2+ as carbonate al lowing for higher adsorption of the collector.

The connective tissue sheaths of paravertebral tendons (peritenons) of white laboratory rats treated with silicon dioxide and hyaluronic acid were studied. It was found that peritenones are natural composites with orthogonal anisotropy with a developed system of interstitial porous membranes that regulate tissue hydrodynamic flows. The extracellular matrix of peritenons contains carbonate-hydroxyapatite and calcium hydroxide in the amorphized state. Silicon dioxide and hyaluronate form hydrophobic silicate and hyaluronate coatings of collagen fibrils (encapsulation), strengthen bonds in Amides I, II, III, reduce the intensity of the bands of bound hydroxyl and stretching vibration bands of phosphate groups, which indicates the replacement of OH groups with carbonate ions and the suppression synthesis of hydroxyapatite. A key mechanism for reducing the intensity of apatitogenesis is the encapsulation of collagen fibrils, accompanied by screening the centers of epitaxial interactions that are structured during heterogeneous nucleation of calcium phosphates. In SBF biomimetic fluid, the deforming effect of modifying agents is leveled, but hydration and decomposition of fibrillar collagen increase. Moreover, against the background of excess supply of exogenous phosphates and carbonates from SBF, apatitogenesis in peritenons is carried out mainly by the mechanism of homogeneous nucleation.

Early-age carbonation can make a significant difference in the formation of hydration products in cement-based materials and alter the microstructural and mechanical performances. To understand in detail the impacts and their contribution to cement hydration, dry-mix cement pastes were exposed to instant carbonation with 0.04 %, 1%, 3%, 10 %, 20 % CO2 concentrations for 2 h prior to further water curing. By increasing the CO2 concentration, an increment in strength gain of samples at 2 h (right after early carbonation) as well as being prolonged by water curing at 1, 3, 7 days was noticed. This agrees with TGA and XRD results, demonstrating that the increases in CO2 concentration resulted in a higher carbonation reaction and hydration degree. 29Si NMR results also indicate that the higher the CO2 concentration the lower the calcium to silica ratio (Ca/Si); thus, there is a higher degree of polymerization to promote early hydration. It can be concluded that early carbonation of 2 h in particular with a high CO2 concentration can be beneficial for further cement hydration due to the consumption of calcium hydroxide (CH) and nuclei site effect of calcite crystals, resulting in better microstructural properties and mechanical performance.

Pimelic acid and calcium hydroxide were used to attach calcium pimelate to the surface of graphene oxide. The additive was mixed with isotactic polypropylene granulate. Neat polypropylene and polypropylene with functionalized graphene oxide was extruded into fibers under laboratory conditions. The gravity spun fibers containing different concentration of the additive and the fibers taken at various velocities were obtained. Morphology and elemental composition of functionalized graphene oxide were studied by means of scanning electron microscopy and energy dispersive X-ray spectroscopy. The structure of fibers was examined by means of differential scanning calorimetry and wide-angle X-ray scattering. The ability of calcium pimelate supported on the surface of the graphene oxide to nucleate the β-form of polypropylene was revealed. A considerable amount of the β-form crystals was obtained in the gravity spun fibers. In the fibers taken at moderate and higher velocities the β-form disappeared. The structure of the fibers extruded with the additive was similar to the structure of the fibers extruded from neat polypropylene. At moderate velocities, the content of mesophase in the structure was high. At higher velocities, the crystalline structure built only from α-form crystals was obtained. The paper presents a discussion of the changes observed in the fiber structure in connection with polypropylene nucleation.

Many studies on calcium hydroxide [Ca(OH)2] as a chemical heat storage material have been conducted. Generally, calcium hydroxide undergoes a dehydration reaction (heat storage operation) efficiently at about 400 °C or higher. In this study, we aimed to lower the dehydration reaction temperature and increase the dehydration reaction rate to expand the applicability of calcium hydroxide as a chemical heat storage material. For the purpose of improving the dehydration reactivity, calcium hydroxide with added lithium compounds was prepared, and the dehydration/hydration reactivities were evaluated. From the results, it was confirmed that the addition of the lithium compounds lowered the dehydration reaction temperature of calcium hydroxide and enhanced the reaction rate. The dehydration reaction of Ca(OH)2 with Li compounds proceeded efficiently even at 350 °C, and the reversibility of the dehydration/hydration reaction was confirmed. The reason for the improvement of the calcium hydroxide dehydration reactivity upon the addition of a lithium compound was examined from the viewpoint of its crystal structure. It was presumed that when lithium ions enter the calcium hydroxide crystals, the crystals became fragile and the dehydration reaction was accelerated.

The removal of Cr, sulfates and Chemical Oxygen Demand (COD) from industrial tannery wastewater by chemical precipitation was carried out using Calcium oxide (CaO) and Calcium hydroxide (Ca(OH)2). Different doses of alkalis, ranging from deficiency to excess hydroxyl species over the stoichiometric necessary, were used to remove theoretically the 100% of Cr [0.3–3.2 g alkali·(g Cr3+)−1]. The precipitation was carried out at room temperature, 10 min of vigorous stirring, 200 r⋅min−1 and a settling time of 24 h, followed by separation and characterization of liquid product. As result of addition of alkalis, pH underwent increase as did the alkali concentration. The removal of Cr, and sulfates also increased as alkali concentration did, although for first species the changes at higher alkali contents were less evident. COD removal on the other hand, did not follow a unique trend, instead exhibited a maximum. Based on our results, selection of a specific dose of alkali was carried out taking as reference the efficiency on total chromium removal, keeping the pH in the range 7 to 9 to ensure Cr precipitation as chromium hydroxide. With those conditions, jar test was used to produce enough liquid product in order to determine the removal percent of several other species. The removal percent of the species was as follows: Cr, SO42−, ZnSO4, FeSO4, CN−1, NiSO4, Fe2[Fe(CN)6] at 99.8%, 66.9%, 99.6%, 21.4%, 70.9%, 52.8% and 76.4% with CaO, and 99.8%, 61.6%, 99.9%, 7.1%, 84.0%, 54.4% and 90.5% with Ca(OH)2, respectively.

The investigation herein reports on the development of bioparticles by mixing calcium pectate with chitosan in order to chelate Cu+2 from water polluted with heavy metals. Calcium pectate was used to synthesize these bioparticles. The pectate was obtained from orange albedo, which was in turn obtained from shredded and dry biomass, treated with an acidulated solution in order to eliminate the pectin (Ps). The first treatment given to the biomass was with a sodium hydroxide solution (NaOH), in order to de-methoxylate the pectin. Subsequently, the biomass was treated with ethyl alcohol and calcium hydroxide (Ca(OH)2) to a temperature of 80 - 90°C, to renew the pectin. This improved the mechanical stability that this constituent requires. Experimental results of the Cu+2 ions are expressed as a withholding rate percentage in time.

Chemical science 11(9), 2350 - 2355 (2020). doi:10.1039/C9SC06224F, Using the mechanosynthesis of the calcium urea phosphate fertilizer cocrystal as a model, we provide a quantitative investigation of chemical autocatalysis in a mechanochemical reaction. The application of in situ Raman spectroscopy and synchrotron X-ray powder diffraction to monitor the reaction of urea phosphate and either calcium hydroxide or carbonate enabled the first quantitative and in situ study of a mechanochemical system in which one of the products of a chemical reaction (water) mediates the rate of transformation and underpins positive feedback kinetics. The herein observed autocatalysis by water generated in the reaction enables reaction acceleration at amounts that are up to 3 orders of magnitude smaller than in a typical liquid-assisted mechanochemical reaction., Published by RSC, Cambridge

Purpose This study aims to retard the setting reaction of CSC by mixing it with 2% chlorhexidine gel (CHX) which will be used as an intracanal medicament, and to evaluate the removal of the experimental medicaments from the root canal. Materials and Methods White Portland cement, white ProRoot MTA and Biodentine were mixed with 2% CHX. The setting time, flowability and film thickness of the CSC/CHX mixture (experimental medicaments) were assessed and measured following the standards of ISO specification. Calcium ion release was measured using ICP-OES, while pH was tested using a pH meter. Moreover, twenty single-rooted teeth were filled with the experimental medicaments for seven days, then the medicaments were removed and the samples analyzed using SEM. Calcium hydroxide paste was used as a control. Results The setting time of the experimental medicaments was inhibited until 84 days. The calcium ion release of the experimental medicaments was significantly higher compared to the control over the period of 14 days (P 0.05). However, the flowability of the experimental medicaments was significantly higher than the control (P

International audience; Calcium oxide, calcium hydroxide and calcium carbonate were tested for the CO2/CH4 reaction in a dielectric barrier discharge plasma reactor under humid conditions. It appeared that the presence of water in the gas stream enhanced slightly the selectivity to CO and H2 syngas on each support (2 to 5 %), contrary to the selectivities to CxHy that decreased (0.5 to 2 %). The water showed little effect on oxygenates selectivities (in the order of 0.1%) compared to dry treatment. The three materials were characterized by thermogravimetric analysis and infrared spectroscopy prior and after, dry and humid, plasma treatments. Addition of humidity in the plasma gas stream led to the formation of calcium hydroxide on the surface of CaO and enhanced the carbonation of Ca(OH)2. We showed that the carbonation of Ca(OH)2, H2O proceeded through simultaneous CO2 capture and H2O release, highlighting an oscillating behavior.

This paper studies of the use of nanocrystalline cerium dioxide with artificially formed bone tissue defects. The results of morphometry confirmed the antialterative effect in the early stages of the reparative process of damaged bone tissue. When using calcium hydroxide with nanodispersed cerium dioxide, the nature of osteogenesis should be characterized as activated. In case of damage to the dentin of the roots of the teeth, dentinogenesis in presence of CeO2 occurs with the formation of a combined dentin and bone regenerates. Little or no studies of dentinogenesis in presence of CeO2 were performed by other researchers.

Introduction: A pivotal issue to achieve success in the treatment of the root canal is root canal disinfection. One of the most important bacteria that infect the root canal is Enterococcus faecalis. This study seeks to examine the effectiveness of 3 methods for disinfecting the root canal: photodynamic therapy, modified triple antibiotic paste (MTAP), and calcium hydroxide. Methods: Sixty-two single-rooted extracted anterior teeth were collected. After cleaning and disinfecting the teeth, their crowns were cut at the CEJ point. The root canals were shaped to the working length up to file F3 ProTaper (F1, F2, F3). EDTA 17% and sodium hypochlorite 2.5% were used for 5 minutes to wash and remove the smear layer, and then the apical foramen was sealed using composite. After that, the teeth were sterilized in an autoclave at 121°C for 15 minutes. Then 10 samples were taken randomly as the negative control. The remaining samples were immersed and cultivated in a suspension containing E. faecalis for 21 days. Then the samples were divided into 5 groups: 2 positive control groups, 1 group treated with the antibiotic paste with the concentration of 1 mg/mL, 1 group treated with calcium hydroxide, and 1 group treated with photodynamic therapy. Then, to collect the biofilm, the ProTaper file F4 was used. After that, the microbial suspension was provided and counting the colonies was carried out to compare the groups. Results: The findings indicated that the amount of CFU/mg of MTAP samples, including clindamycin, metronidazole, ciprofloxacin in the concentration of 1 mg/mL and photodynamic therapy and calcium hydroxide was lower than that in the control group. Antibiotic paste cleansed the root canal up to 99.9%. Photodynamic therapy reduced the amount of CFU/mg to 98.8%, and calcium hydroxide reduced the amount of CFU/mg to 94.13%. Conclusion: Using photodynamic therapy causes a reduction in the biofilm and inhibits the growth of the E. faecalis bacterium. In addition, in this study, MTAP with a concentration of 1 mg/mL was used, which expunged the bacteria completely. Meanwhile, calcium hydroxide had the weakest effect of all on the E. faecalis bacterium.

High-quality Al2O3 porous ceramic planar membranes suffer from severe deformation and cracking, which occur during sintering process. This study reports on solving this problem, by introducing calcium hydroxide powder in the alumina slurry. Phase-inversion tape-casting technology, applied during molding, and sintering at 1550 °C, favored an in-situ expansion reaction, which effectively suppressed deformation, and well-formed and crack-free calcium hexaluminate porous planar membranes were obtained. The produced membranes had a low thermal conductivity (0.69 W·m−1 K−1 at 85 °C), ascribed to the in-situ formed plate-like structure of calcium hexaluminate (CA6) and to the high porosity. After hydrophobic modification, the membranes were applied in membrane distillation processing. High rejection rate (>99.9%) and water flux (19.8 L·m-2 h−1) were achieved at 85 °C, using a 4 wt% NaCl solution as a feed solution.