Calcium Hydroxide Suspension Research Articles

The influence of cavitation on the phase-disperse state of hydrated calcium oxide

The effect of cavitation phenomena excited by ultrasonic radiation and in a jet-type hydrodynamic cavitator on the change in the phase-dispersed state of hydrated calcium oxide was investigated. The influence of the conditions of cavitation activation of calcium hydroxide on the sedimentation stability of its suspension was established. Based on the analysis of the intensity of sedimentation of Ca(OH)2 particles after cavitation treatment of calcium hydroxide suspension, the probable course of this process in different time periods is proposed. According to the Stokes equation, the distribution of particles by dispersion was calculated, and the dynamics of particle size changes depending on the specific energy introduced into the suspension by cavitation devices were determined. It was established that after cavitation activation, Ca(OH)2 particles acquire a charge, due to which the phase state of calcium hydroxide changes, and its reactivity will increase.

Kinetics and structure analysis of CO2 mineralization for recycled concrete aggregate (RCA)

CO2 mineralization of solid waste in the construction industry for green concrete production is a promising approach for economically storing CO2 and recycling solid waste. Recent investigations have underscored the significance of CO2 sequestration and the augmentation of RCA performance engendered by the holistic reaction processes. While there is a pronounced interest in the optimization of macroscopic reaction conditions (e.g., temperature, pressure, etc.), the exploration and enhancement of the reaction kinetics stage often remains under explored. This study employed a reaction kinetics model to quantify the reaction rate unveiled two distinct reaction stages within the mineralization reaction. Early evaporation and pore formation established the groundwork for the diffusion mechanism of gas product layers in the middle and later stages, emphasizing the crucial role of water in connecting solid ion leaching and gas dissolution-diffusion in the reaction. The water content of the reaction has an optimal value (4%–6%), smaller particle size correlates with a higher optimal water content. Pre-soaking with a calcium hydroxide (CH) solution or suspension was employed to improve mineralization reaction kinetics, resulting in RCA with improved pore characteristics and strength. The crushing index decreased by 28.8% and 21.8%, the water absorption rate decreased by 11.1% for both coarse and fine RCA, and the cumulative total porosity of fine RCA decreased by 17.6%. This research aims to broaden the applications of waste concrete in the CO2 capture, utilization and storage (CCUS) industry and produce low-cost, extensively processed, and high-strength RCA products while contributing to sustainable CO2 management.

Sensory and aroma impact of mitigation strategies against sunburn in Riesling

Climate change is an environmental challenge that impacts the wine industry due to frequent sunburn damage triggered by heat waves, sun radiation and severe water deficits. This leads to severe yield losses and sensory changes in the resulting wines, presumably caused by climate-induced off-flavours. This study aims to develop viticultural and oenological strategies to mitigate sunburn damage in the highly sensitive variety Riesling and its detrimental sensory properties. In 2020, we combined the timing and intensity of defoliation measures with the application of kaolin and calcium hydroxide suspensions, reflecting a portion of the solar radiation. Seven treatments were replicated in three field experiments. Grapes from each field replication were maintained as a fermentation replication and, therefore, separately vinified following a standardised protocol. Replicates, including field and fermentation replicates, were further used as sensory replications. Descriptive analysis (DA) and temporal dominance of sensations (TDS) revealed a significant sensory impact of experimental trials in eight of twelve attributes. Additionally, wines were analysed by gas chromatography-mass spectrometry. The early sun exposition treatment with partial defoliation of the grape zone after flowering, followed by a second defoliation at berry closure, reduced fruity aroma but increased smoky notes due to enhanced 4-vinylguajacol formation as well as the intensity of the atypical ageing note (ATA) reminiscent of acacia blossom, naphthalene and fusel alcohols. Applying kaolin or calcium hydroxide particles on the berry skin slightly mitigated these unpleasant effects and even increased fruitiness and sweetness. Late defoliation at berry closure diminished the green note, which was most prominent in the non-defoliated control. Further smokiness and ATA intensities were lowered, in contrast to their rise due to early defoliation. However, late defoliation increased 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), causing the petrol off-flavour. TDS analysis revealed a higher fruity and sweet dominance during the first 10 seconds due to early defoliation, while late defoliation fostered dominant and lingering sourness. In conclusion, early defoliation, which lowers sunburn incidence due to an early adaptation towards sun exposure, increases smoky and ATA flavours and diminishes fruitiness. These detrimental sensory effects could be significantly mitigated by applying reflecting particles of kaolin and calcium hydroxide on berry skins.

Influence of Citric Acid-Assisted Impregnation of Recycled Aggregate on the Properties of the Resultant Concrete.

The paper presents the results of tests on concrete with recycled aggregate impregnated with the use of citric acid. Impregnation was carried out in two stages, with a suspension of calcium hydroxide in water (so-called milk of lime) or diluted water glass used as the second impregnant. The mechanical properties of the concrete were carried out: compressive strength, tensile strength and resistance to cyclic freezing. In addition, concrete durability parameters such as water absorption, sorptivity and torrent air permeability were investigated. The tests showed that this type of impregnation did not improve most of the parameters of concrete with impregnated recycled aggregate. The mechanical parameters after 28 days were significantly lower compared to the reference concrete, although after a longer curing period, these differences decreased significantly for some series. The durability parameters of the concrete with impregnated recycled aggregate also deteriorated compared to the reference concrete with the exception of air permeability. The results of the tests carried out indicate that impregnation using water glass in combination with citric acid gives the best results in most cases and that the order in which the impregnation solutions are applied is very important. Tests also showed that the effectiveness of impregnation is very much influenced by the value of the w/c ratio.

Use of eggshell waste: A green and effective method for the synthesis of pure calcium hydroxide suspensions

This paper presents a rapid method to obtain pure suspensions of Ca(OH)2 dispersed in 2-propanol. To this aim eggshell wastes (CaCO3) were decarbonated to calcium oxide (CaO) followed by sonication-assisted hydrolysis in water/2-propanol to form calcium hydroxide (Ca(OH)2). An important advantage of the method is that it does not require chemical reagents due to the high purity of eggshell in CaCO3. Moreover, CaO is fully converted into Ca(OH)2 which means that purification steps are not needed, as occurs in conventional routes of synthesis. To assess the reliability of the synthetic procedure, the purity and amount of Ca(OH)2 were studied by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and thermal analysis (TG). In addition, the morphology and crystallite size were examined by transmission electron microscopy (TEM) and X-ray diffraction (XRD) using Rietveld refinement method. It was found that sonicated Ca(OH)2 suspensions (5 g/L) were composed of particles that ranged in size from several nanometers to few micrometers. Finally, the suitability of Ca(OH)2 from eggshell to reinforce architectural stone was also studied by microscopy examination, colour change tests, surface hardness and surface erosion measurements. All tests confirmed the consolidation effectiveness was comparable to conventional nanolime treatments and surface erosion was visibly reduced.

Evaluation of the stability of heavy metal-containing sediments obtained in the wastewater treatment processes with the use of various precipitating agents

The article presents the results of research on the leachability of selected heavy metals (cadmium, nickel, chromium, cobalt, lead, and copper) from solid waste obtained in laboratory processes involved in the industrial treatment of wastewater generated in metal surface treatment plants. The test sludges were precipitated using sodium hydroxide solution, calcium hydroxide suspension, 45% solution sodium trithiocarbonate (Na2CS3), 15% solution trimercapto-s-triazine, sodium salt (TMT), and 40% solution sodium dimethyldithiocarbamate (DMDTC). The precipitates were treated with artificial acid rain and artificial salt water. After 1, 7, 14, and 21 days of leaching, the concentration of Cd, Co, Cr, Cu, Pb, and Ni in the leachate was determined. Artificial acid rain leached Ni and Cd to a maximum concentration of 724 mg/L and 1821 mg/L, respectively, from the sludge obtained after the application of Na2CS3, while artificial salt water leached Ni in the maximum amount of 466 mg/L and Cd—max. 1320 mg/L. When Ca(OH)2/NaOH was used, the leaching of Cr reached a similar level for both leaching agents, i.e., the maximum for artificial acid rain was 72.2 mg/L and the maximum for artificial salt water 71.8 mg/L. The use of Na2CS3 or Ca(OH)2/NaOH poses a risk of some heavy metals entering the environment, which may have a negative impact on living organisms, whereas the sludges obtained with the use of DMDTC and TMT as precipitants were the most stable under the experimental conditions and did not pose a potential environmental hazard.

Reaction of Carbon Dioxide Gas Absorption with Suspension of Calcium Hydroxide in Slurry Reactor

Chemical phenomena involving three phases (solid, liquid, and gas) are often found in the industry. Carbonate (CaCO3) is widely used in industries as a powder-making material in the cosmetic industry, a pigment in the paint industry, and filler in the paper and rubber industry. This research aim to study the ordering process carbonate deposits (CaCO3) from the absorption process of CO2 gas with Ca(OH)2 suspension. The absorption reaction of CO2 gas with Ca(OH)2 suspension was carried out in a stirred slurry tank reactor. Initially, the reactor containing water was heated to a certain temperature, then Ca(OH)2 was added to the reactor. Furthermore, CO2 gas with a certain flow rate and temperature (according to the reactor temperature) is flown with the help of a gas distributor. Samples were taken every 1 min until the concentration of Ca(OH)2 could not be detected (completely reacted). The variables in this study were: stirrer rotation speed (5.66711.067 rps), CO2 gas flow rate (34.0127–60.5503 c/s), and temperature (30–50°C). The mass transfer coefficient and the reaction rate coefficient were determined by minimizing Sum of Squares of Errors (SSE). This experimental process follows a dynamic regime. A dimensionless number relationship for the gas-liquid mass transfer for the value range is Re1 = 18928.76-38217.20, Sh = 0.07928 Reg0.4383 Rel0.4399 Sc0.6415 with an error of 5.19%. The dimensionless number relationship for solid-liquid mass transfer is Sh = 0.0001179 Reg0.4674 Rel0.5403 Sc1.444 with an error of 7.31%. The relationship between the reaction rate constant and the temperature in the 30-50 °C range can be approximated by the Arrhenius equation, namely kr = 1771000 e-2321.4/T cm3/mgmol/s with an error of 3.63%. Doi: 10.28991/ESJ-2023-07-02-02 Full Text: PDF

A new method to rapidly evaluate the activity of volcanic ash materials

A new method of preliminary determination of pozzolanic activity, total dissolved solids (TDS) method, was proposed and experimental investigation was carried out on fly ash (FA). The electrical conductivity, TDS, pH and hydration temperature parameters of FA and calcium hydroxide (CH) suspension were investigated. First-order derivation of TDS was performed, dividing steady-state and unsteady-state dissolution regions. Results suggested that the first-order derivation of TDS can measure the dissolution rate, and was a potential method for evaluating solubility. The first derivative of TDS indicated that the system gradually changes from the unsteady state to the steady state stage. The concept of TDS loss rate was proposed mainly to avoid the effect of CH in the CH-FA–CSH–CAH system, and to highlight the effect of the gelation products generated by the pozzolanic reaction on TDS. The higher the loss rate of TDS, the stronger its pozzolanic activity.

A resource efficient and environmentally safe charge structure for mining in an open-pit

Purpose. The purpose is to reduce mineral losses during the explosive destruction of rocks and environmental pollution by harmful gases and fine particulate matter. Methods. To achieve the objectives of the study, methods of physicochemical analysis and mechanics of continuous media have been used. The method of physico-chemical analysis has been used to determine the quantitative and qualitative characteristics of the composition of the well stemming depending on the parameters of the well, the type of explosive, the amount and type of harmful gases formed during the explosion. Methods of solid medium mechanics have been used to establish the patterns of pressure waves during an explosion depending on the characteristics of the gap filler between the charge and the well wall. To solve the problem of the behavior of a two-layer medium during the loading of a cylindrical cavity by a nonstationary load, a numerical method based on the finite-difference McCormack predictor-corrector scheme has been used. Findings. A resource-saving and environmentally friendly charge structure for rock mining by explosion was developed. The design of the charge involves the formation of a gap between the charge and the wall of the borehole, and filling it with a suspension of calcium hydroxide or a suspension of calcium carbonate. Originality. SThe dependences of the volume of harmful gases (NO2, CO2, CO) formed during the explosive destruction of rocks and the magnitude of the pressure peak in the area close to the charge on the chemical composition of the filler of the radial gap between the charge and the well wall have been set. Practical implications. Developed charge design allows to neutralize the harmful gases formed during the explosion, to reduce the pressure peak in the area of the rock massif close to the charge, and can be widely used in non-metallic quarries that extract minerals for the production of crushed stone.

Influence of fluoride preparations for the prevention of dental caries on the enamel solubility

The aim of the study is to evaluate the effectiveness of a number of popular fluorine-containing caries prophylactic drugs by determining the level of solubility of tooth enamel in laboratory conditions. For testing fluorine-containing preparations, three observation groups were formed: Group I - using the preparation with the content of fluorides 4%; Group II - with a preparation for deep fluoridation of enamel, consisting of a liquid saturated with fluorine, copper and magnesium, as well as a suspension of calcium hydroxide; Group III - with a three-component gel based on carboxymethyl cellulose (CMC) the content of fluorides 1.5%. The study was carried out by using the method of «enamel windows» and modeling in the laboratory the processes of both natural and pathological solubility of tooth enamel and determining the level of its solubility by analyzing the decalcifying solution of the oral fluid for the content of calcium and phosphorus ions in it. In the course of the study of fluorinated karyoprophylactic preparations on the enamel surface, according to the observation group, the most active karyoprophylactic fluorinated compositions were identified. The data obtained from laboratory studies allow us to formulate clear recommendations for practical health care for the most effective use of the properties of the tested fluorine-containing drugs for prophylactic purposes or in relation to the therapy of focal demineralization of enamel: to obtain the most effective result of the prevention of dental caries in the conditions of practical dental treatment, we recommend applying gel fluoride preparations, and in the treatment of initial caries of the enamel of the teeth, give preference to systems for deep fluoridation of the enamel of the teeth.

Synthesis of biocompatible calcium-phosphate compositions in ultrasound field

Introduction reflects the great interest of practical restorative medicine in artificial structures that mimic the structure and properties of natural bone tissue that are made from biocompatible composite materials suitable for restoring the integrity of bone elements of the musculoskeletal system. The Introduction also contains the physicochemical foundations and approaches to a new ultrasonic technologies providing accelerated production of a biocompatible composite material, precisely hydroxyapatite particles in a collagen matrix. Experimental part contains a description of methods and equipmets for accelerated production of a hydroxyapatite suspension in the field of a hydroacoustic emitter, which ensures that the cavitation threshold at room temperature is exceeded, at which intense acoustic vortex microflows provide a decrease in diffusion restrictions, accelerating the interaction between reacting components. The reaction is carried out with the simultaneous supply of an aqueous solution of calcium monophosphate hydrate and a suspension of calcium hydroxide. The resulting finished product is separated using an ultrasonic self-cleaning filter, where the same, by nature, microflows allow the implementation of a continuous accelerated separation of synthesized particles in an ultrasonic self-cleaning filter of the installation, where, after separation, the precipitate is also subjected to cleaning. The resulting particles of hydroxyapatite mixed with the solution collagen and homogenized in an ultrasonic field at frequency of 22 kHz and an energy density in the reaction volume from 1 to 10 W / cm3. Obtained homogenate can be easily used to create various implant designs with predetermined sizes and shapes and after freezedrying was transformed in biocompatible composite with a porous structure. To control biocompatibility, samples of this composite in form of thin plate was sewed under the skin into the scruff of white lab rats. A suspension of hydroxyapatite mechanically combined with the collagen during 30 s homogenization by ultrasound at frequency of 22 kHz and at energy density of 3 W / cm3, form a complex that is freeze-dried, after which it can be used to form the biocomposite body with porous structure and with given dimensions and shapes. Subcutaneous implantation of plates of a calcium-phosphate biocomposite with a biodegradable polymer collagen, into the scruff of a laboratory white mouse showed its good biocompatibility with tissues of a living organism, without causing either immediate or delayed adverse events in them.

Properties of fine Sr2+-substituted hydroxyapatite synthesized using ultrasonication

This study investigated the properties of fine Sr2+-substituted hydroxyapatite (SrHAp) synthesized using ultrasonication. SrHAp was synthesized by the addition of phosphoric acid solution to an ultrasonicated calcium hydroxide suspension containing strontium hydroxide. The X-ray diffraction peaks for SrHAp were shifted to low angle with increasing Sr/(Ca + Sr) atomic ratio. X-ray diffraction, energy dispersive X-ray spectroscopy and inductively coupled plasma spectroscopy measurements confirmed that HAp and strontium apatite (Sr10(PO4)6(OH)2;SrAp) formed a complete solid solution. When the Sr/(Ca + Sr) atomic ratio was 0.3 or less, the (Ca + Sr)/P atomic ratio was 1.67 or less, and the specific surface area was also large. The bending strength of a SrHAp sintered body was increased and the bending strength of the SrAp sintered body became 40 MPa when the Sr/(Ca + Sr) atomic ratio was above 0.3. The ethanol conversion rate using SrAp as catalyst was 7% for 1 hour and was 40% of HAp reagent. However, selectivity of SrAp from ethanol to butanol was 70%.

Characterization of novel calcium hydroxide-mediated highly porous chitosan-calcium scaffolds for potential application in dentin tissue engineering.

The aim of this study was to develop a highly porous calcium-containing chitosan scaffold suitable for dentin regeneration. A calcium hydroxide (Ca[OH]2 ) suspension was used to modulate the degree of porosity and chemical composition of chitosan scaffolds. The chitosan solution concentration and freezing protocol were adjusted to optimize the porous architecture using the phase-separation technique. Scanning electron microscopy/energy-dispersive spectroscopy demonstrated the fabrication of a highly porous calcium-linked chitosan scaffold (CH-Ca), with a well-organized and interconnected porous network. Scaffolds were cross-linked on glutaraldehyde (GA) vapor. Following a 28-day incubation in water, cross-linked CH scaffold had no changes on humid mass, and CH-Ca featured a controlled degradability profile since the significant humid mass loss was observed only after 21 (26.0%) and 28 days (42.2%). Fourier-transform infrared spectroscopy indicated the establishment of Schiff base on cross-linked scaffolds, along with calcium complexation for CH-Ca. Cross-linked CH-Ca scaffold featured a sustained Ca2+ release up to 21 days in a humid environment. This porous and stable architecture allowed for human dental pulp cells (HDPCs) to spread throughout the scaffold, with cells exhibiting a widely stretched cytoplasm; whereas, the cells seeded onto CH scaffold were organized in clusters. HDPCs seeded onto CH-Ca featured significantly higher ALP activity, and gene expressions for ALP, Col1, DMP-1, and DSPP in comparison to CH, leading to a significant 3.5 times increase in calcium-rich matrix deposition. In sum, our findings suggest that CH-Ca scaffolds are attractive candidates for creating a highly porous and bioactive substrate for dentin tissue engineering.

ОЧИСТКА ГАЛЬВАНОСТОКОВ ПРЕДПРИЯТИЯ «ТХИЕН МИ» (ВЬЕТНАМ) С ИСПОЛЬЗОВАНИЕМ ОПИЛОК И ИОННОГО ОБМЕНА

The technology for wastewater treatment of galvanic production was developed for «Thien Mi» LLC, Vinh Fuk, Socialist Republic of Vietnam. Initially, a characteristic of the existing method for the extraction of heavy metal ions from electroplating is given. It was revealed that the treatment of wastewater from galvanic plants with a suspension of calcium hydroxide leads to the formation of a large volume of galvanic sludge and an insufficient degree of purification from heavy metal ions. The possibility of sorption purification of the galvanic drains of the named enterprise using the sawdust of acacia (Acacia auriculiformis) as a sorption material was investigated. The adsorption isotherms of Cu2+, Ni2+, and Zn2+ ions with native sawdust of acacia were constructed. Sorption material was processed with weakly concentrated solutions of sulfuric acid, which leads to an increase of more than 4 times in the sorption capacity of the mentioned ITMs. The post-treatment of galvanic solutions from heavy metal ions was carried out using the Lewatit Monoplus TP 207 ion-exchange resin. The toxicity of the initial galvanic drains was investigated after each cleaning step using standard test objects Paramecium caudatum and Daphia magna. As a result of the studies, sorption and ion-exchange methods are recommended for the treatment of wastewater of galvanic production of small volumes, which can significantly reduce the concentration of heavy metal ions in purified solutions.

Antibacterial power effectiveness of calcium hydroxide and propolis mixture on Fusobacterium nucleatum bacteria

Background: Calcium hydroxide is a root canal dressing material that is widely used in dentistry because of its ability to regenerate hard tissue and eliminate bacteria. According to Ferreira et al. (2015), Fusobacterium nucleatum was found in 90% of teeth that had a root canal treatment done using calcium hydroxide as an intracanal medication. Due to this shortcoming of the antibacterial power of calcium hydroxide, additional research on alternative ingredients that can be combined with calcium hydroxide to improve its antibacterial power is necessary. Propolis is a natural material that has high antibacterial power and has long been used in dentistry. The addition of propolis to calcium hydroxide is expected to improve the antibacterial power of calcium hydroxide without eliminating its function in terms of regenerating hard tissue. Purpose: To find out how effective is the antibacterial power of a combination of calcium hydroxide and propolis against Fusobacterium nucleatum. Methods: The research was carried out using 4 treatment groups consisting of 6 samples for each group. Group 1 is given a combination of calcium hydroxide and propolis with a ratio of 1:1, group 2 with a ratio of 1:1.5, group 3 with a ratio of 1:2, and group 4 is a positive control of calcium hydroxide and sterile aquadest suspension. Each sample was put into a test tube containing BHIB and a suspension of Fusobacterium nucleatum, incubated at 37ºC for 24 hours, and vortexed for 1 minute. A total of 0.1 ml of bacterial inoculum was taken from each sample and then put into the MHA and grown for 24 hours. The number of Fusobacterium nucleatum colonies grown on MHA was calculated and expressed using the Colony Forming Unit (CFU). Results: There were fewer colonies of Fusobacterium nucleatum in the treatment group compared to the control group. Conclusion: The combination of calcium hydroxide and propolis has an effective antibacterial power against Fusobacterium nucleatum which the ratio of 1:2 is more effective than ratio of 1:1,5 and 1:1.

Research of textural and structural features of refractory gold-bearing ores

The article studies the material and mineralogical composition of the refractory gold-bearing ores of the weathering crust of one of the deposits in Eastern Siberia. It is revealed that, according to the textural and structural features, ores are multi-mineral and have significant differences in the composition of the detrital, granular material and the loose component. All ore is saturated with iron hydroxides and limonite crusts with clay components. The results of the analysis showed that large classes contain an insignificant amount of a valuable component. Increased gold content is noted starting from -4 + 0 mm size. In the free state are about 3-5%. Processing of these types of raw materials is a rather complicated task. Analysis of the enrichment methods showed that the use of new solvents of noble metals with their subsequent concentration is promising. Of practical interest are alkaline solutions obtained by dissolving sulfur in an aqueous suspension of calcium hydroxide. The reagent is non-toxic and environmentally friendly. Leaching was carried out in a wide range of concentrations of the solvent used. The optimum solvent concentrations and the duration of the leaching process for extracting the valuable component into the filtrate were determined to be 97–98%. Chemical analysis of cakes showed that the reagent does not enter into chemical interaction with other elements that make up the ore. As well as the content of elemental sulfur in dump cakes averages 0.64%, that is, it corresponds to a content in the raw material of up to 0.8%. At the same time, cakes are not environmentally harmful and can be stored on special platforms.

The CRATI Project: New Insights on the Consolidation of Salt Weathered Stone and the Case Study of San Domenico Church in Cosenza (South Calabria, Italy)

This paper presents the results of a laboratory experimentation carried out on stone materials in the framework of the CRATI project (Knowledge and Restoration through Advanced Integrated Technologies) aimed at testing new products with consolidating properties by means of an integrated methodological approach. After the preliminary characterization of stone materials collected in the pilot site, the second stage of the activities within the project were focused on the formulation and testing of products for the conservation of the same materials against decay, especially salt crystallization, one of the most aggressive and common degrading processes. The San Domenico Church, located in the old town of Cosenza (Calabria, Southern Italy) has been chosen as the pilot site and for the in situ tests. Several specimens with the same features of the stone materials used in San Domenico church were collected from a historical quarry near the city of Cosenza. These specimens were treated and then artificially degraded by salt crystallization tests in order to evaluate their susceptibility to weathering intensity. Three different consolidating products were used; respectively, two commercial and another one formulated in laboratory: (a) a suspension of nanosilica (Nano Estel®); (b) a suspension of nanolime (CaLoSiL®), and (c) a suspension of nano calcium-hydroxide dispersed in isopropyl alcohol and then mixed with diammonium hydrogen phosphate. A systematic approach, including minero-petrographic, geochemical and physico-mechanical techniques, was applied to evaluate (a) the nature and main features of materials; (b) the efficacy of consolidating treatments, and (c) the resistance of treated stone to the salt crystallization processes. The tested products demonstrated a significant efficiency to consolidate and protect stone material samples, enhancing their resistance to salt crystallization. Thus, such a case history may be useful in order to plan appropriate restoration interventions that consider the interactions between the building stone and the protective/consolidating product.

APPLICATION OF ANTISEPTIC AND OSTEOPLASTIC DRUG FOR DESTRUCTIVE PERIODONTITIS TREATMENT

Introduction: Treatment of destructive forms of chronic periodontitis is extremely topical. Its relevance is associated with the features of treatment, which depends on the stage of the exacerbation process. The issue of the problem is also in the fact that the destructive seat of periodontitis is a source of chronic infection. The aim: The task of the research was to evaluate the conservative treatment of chronic destructive forms of periodontitis with a dental kit "Cupratin", developed for professional usage in dental practice. Materials and methods: "Cupratin" is a complex medicament based on suspensions of calcium hydroxide, copper-calcium hydroxide and powder, which contains hydroxide aluminosilicate and calcium sulphate, radiopaque filler. It has bactericidal and osteoplastic effect. The treatment involved 44 patients (44 teeth) in the age group of 37 to 50 years suffering from chronic granulating periodontitis without concomitant diseases. Patients were divided into two groups: investigated and control. In the main group of patients, a suspension on the basis of copper-calcium was used for treatment (root canals were filled with "Cupratin" as a temporary filling material). Obturation of canals was preceded by chemical and mechanical treatment. The medical material was in direct contact with periodontal tissues for 20-55 days. Intraoral X-ray radiography was taken from the patients within the intervals of 3 and 6 months. Results and conclusions: Positive results were obtained, which were characterized by the disappearance of subjective symptoms, intensive bone tissue reconstruction in the site of destruction and a decrease in the size of the destruction respectively.

Synthesizing Alkaline Earth Metal Hydroxides Nanoparticles through an Innovative, Single-Step and Eco-Friendly Method

The objective of this paper is to introduce a patented and eco-friendly method to synthesize aqueous suspension of all types of alkaline-earth metal hydroxides nanoparticles (NPs). This method is based on an ion exchange process; the exchange takes place at ambient temperature/pressure, starts from cheap or renewable reagents and, in one single step, results in the creation of the crystalline desired nanoparticles in only a few minutes. In terms of structural and morphological features, the synthesized nanoparticles are characterized by means of XRD-Rietveld refinement, FTIR, and TEM. In particular, we obtained pure and crystalline magnesium and calcium hydroxide suspensions, showing the typical brucite crystal structure with a hexagonal lamellar morphology and dimensions generally <100 nm. With respect to the strontium and barium hydroxide suspensions, we observed different kinds of hydroxides (either anhydrous and hydrate forms), characterized by orthorhombic or monoclinic crystal lattices with rod-like nanostructured morphologies. Despite the different morphologies, all synthesized nanoparticles appear constituted by a superimposition of primary nanoparticles, of dimensions ranging from a few to 15 nm, correlated to the increase in the atomic number of the alkaline earth metal.

Clinical evaluation of oily calcium hydroxide suspension alone and in combination with β-tricalcium phosphate in the treatment of periodontal intrabony defects

Background: An oily calcium hydroxide suspension (OCHS) has been proved to be efficient in promoting bone regeneration in periodontal intrabony defects. However, the outcome of regenerative therapy using an OCHS as an adjunct to open-flap debridement is believed to be compromised by its low consistency. Thus, the present study was carried out to evaluate an OCHS alone and in combination with β-tricalcium phosphate (β-TCP) as a bone graft material in the treatment of periodontal intrabony defects. Materials and Methods: Twenty-six intrabony defects in 10 patients were divided into experimental and control sites. The experimental sites were debrided and grafted with a combination of OCHS and β-TCP. The control sites were debrided and grafted with OCHS alone. Probing pocket depth (PPD), clinical attachment level (CAL), and gingival margin position were recorded at baseline and at 3, 6, and 9 months. Results: No differences in any of the investigated parameters were observed at the baseline between the two groups. At 9 months postoperatively, the experimental group showed a reduction in mean PPD from 7.56 ± 1.15 to 4.19 ± 1.42 mm (P Conclusion: Overall, both therapies led to significant PPD reduction and CAL gain. The combination of an OCHS and β-TCP as a bone graft material was more effective in terms of improving clinical parameters than OCHS alone.