Magnesium Sulfate Solution Research Articles

Toxicity characteristics and durability of concrete containing coal ash as substitute for cement and river sand

The main aim of this study was to investigate the toxicity characteristics and durability of concrete containing bottom ash (BA) and fly ash (FA), as partial or total replacement of fine aggregate and Ordinary Portland cement (OPC), respectively. Concrete mixtures were prepared containing 0, 20, 50, 75 and 100% of BA as a substitute for river sand and 20% of FA as a replacement for OPC. Tests carried out were Toxicity Characteristics Leaching Procedure (TCLP), sulfate and acid attack (change in compressive strength, microstructure and weight) and elevated temperature effects (loss in compressive strength and mass as well as change in pulse velocity). Results showed that submerging coal ash concrete (CAC) mixtures in 5% sulfuric acid solution resulted in less reduction of compressive strength and mass loss compare to that of the control concrete. Moreover, sulfate resistance tests on concrete mixtures indicated that there were no mass loss and no reduction in compressive strength of all the mixtures after submersion in 5% magnesium sulfate solution. CAC showed higher weight loss and greater compressive strength reduction at elevated temperatures. From TCLP results, it is concluded that none of the elements leached higher than the maximum concentration of contaminants for toxicity characteristics. It indicates that transportation, disposal and utilization of BA and FA as clean construction material’s replacement could be utilized to reduce their environmental problems, increase efficiency and reduced unit cost production of concrete.

Effect of calcination temperature of magnesium silicate on the properties of magnesium phosphate cement

This study reports the use of magnesium silicate (M-S-H) for magnesium phosphate cement (MPC) formulation and aims to study the effect of calcination temperature of the magnesium silicate on mechanical properties and setting time of the MPC. Synthetic magnesium silicate was obtained by precipitation method using solutions of magnesium sulfate and sodium silicate with a molar ratio of Mg/Si = 1. MPC mortars were prepared with a mass ratio of magnesium silicate to potassium phosphate of M-S-H/KH2PO4 = 1. Results showed that mortars prepared with magnesium silicate calcined at temperatures above 700 °C did not set into hardened cement. However, calcination of magnesium silicate at temperature below 700 °C and particularly at 600 and 650 °C enhances the mechanical performance of the cement due to improving the availability of magnesium from magnesium silicate powder to react with phosphate for cement phase formation (K-struvite). MPCs with an optimal compressive strength up to 39 MPa at 28 days were obtained with magnesium silicate calcined at 600 and 650 °C.

Synthesis and magnetic properties of Mg doped SnO2 thin films: experimental and Ab-initio study

Mg-doped tin oxide (SnO2) thin films were deposited using spray pyrolysis technique with an aqueous solution of SnCl2 and magnesium sulfate (Mg (SO4)·7H2O) on a heated glass substrate. In this work, the effect of Mg doping on the structural, optical and electrical properties of SnO2 was investigated in some detail by X-ray diffraction, UV–Vis spectroscopy and Hall Effect measurements. The XRD diffractograms demonstrate that SnO2 crystallized in tetragonal rutile structure with preferential orientation along (110) plane. The average transmittance in the visible range was increased from 65 to 78% and the values of energy band gap were found in the range of 3.62–3.87 eV. The lowest resistivity [1.021 × 101 (Ω.cm)] was obtained for the film doped with 5 at% Mg. The electronic structure and optical properties of the rutile structure Sn1−xMgxO2 were obtained by ab initio calculations using the Korringa-Kohn-Rostoker method (KKR) combined with the Coherent Potential Approximation (CPA), as well as CPA confirms our results.

Magnesium in Pain Research: State of the Art.

Magnesium has been shown to produce an antinociceptive effect on animal models of neuropathic and inflammatory pain. It has also been shown to exert an analgesic effect on humans in conditions presenting acute (postoperative pain) and chronic (neuropathic) pain. As it is known that magnesium is a physiological antagonist of the N-methyl-Daspartate (NMDA) receptor ion channel, and that the NMDA receptor plays a key role in central sensitization, the primary mechanism through which magnesium produces its analgesic effect is believed to be blockade of the NMDA receptor in the spinal cord. In addition, magnesium blocks calcium channels and modulates potassium channels. The activation of the nitric oxide (NO) pathway could have an important role in the antinociceptive effects of systemic magnesium sulfate in the somatic, but not in the visceral model of inflammatory pain. Although it is known for some time that intramuscular, intravenous and subcutaneous injections of magnesium sulfate in humans, and intraperitoneal injection in rodents produce local pain sensation, the mechanism of this action was elucidated only recently. It was demonstrated that subcutaneous injection of an isotonic, pHadjusted (7.4) solution of magnesium sulfate (6.2%) to rats produces local peripheral pain via activation of peripheral TRPA1, TRPV1, TRPV4 and NMDA receptors and peripheral production of NO. In animal models of pain, magnesium has been shown to exert both antinociceptive and pronociceptive effects by acting on different ion channels and NO pathways, however, the precise mechanisms remain to be elucidated.

Experimental evaluation of the influence of separate administration of memantine, amantadine and solutions of magnesium sulfate on the microcirculation in the vessels of the posterior pole of the eye after a concussion

For the first 3 hours after simulation of eye contusion in rabbits or 60 minute ischemia with subsequent reperfusion a. ophthalmica in rats, are characterized by hypoperfusion the posterior pole of eyeball. It was manifested by reliable de-escalation of microcirculation factor relatively to its baseline values on average by 8,2 times (injury) and by 39,2 times (reperfusion), respectively. Separate administration of memantine and solutions of amantadine or magnesium sulfate amortized rapid deterioration of blood supply to the eye. By the ability to improve the microcirculation of the eye in the acute post-reperfusion period a single intravenous infusion of amantadine sulfate solution (5 mg/kg intravenously (i/v)) is by 1,5 and 1,4 times better than memantine at a dose of 20 mg/kg intragastric (i/g), or magnesium sulfate (250 mg/kg i/v). In the eye contusion of rabbits, memantine oral administration or intravenous administration of amantadine sulfate in doses of 20 and 2,5 mg/kg contributed to the restoration of blood supply to the eye. This was evidenced by the growth rate relatively to the control of microcirculation pathology groups on average by 4,5 and 6,3 times with the prevalence of the drug "PK-Merz" over the drug "Mema" by 28,5 % on the value of the stimulating effects on blood flow. Improved perfusion of posterior pole of the eyeball against the background of studied modulators of the NMDA-receptor activity (memantine ("Mema") solutions amantadine ("PK-Merz") and magnesium sulfate) underlies their neuroretinoprotective effect.

Durability properties of a non-cement binder made up of pozzolans with sodium hydroxide

The durability property of a mortar is the second most important concerns next to its strength. This study investigates some durability properties of a Non-cement binder (Non-cem). The Non-cem was produced from pozzolans such as slag, palm oil fuel ash, and rice husk ash alongside a 2.5M sodium hydroxide solution. The mortar of Non-cem was tested for its compressive strength, water absorption, porosity, chloride penetration, sulfate, corrosion, and thermal resistance (heated at 700°C for 2h) as well as compared to that of ordinary Portland cement (OPC) mortar. The results reveal that Non-cem mortar gains compressive strength of 42.84MPa (93.36% of OPC) at 28days. Water absorption and porosity at 28days are found to be 8.1% and 16.3% for Non-cem mortar whereas 6.2% and 13.5% for OPC mortar, respectively. The chloride penetration of Non-cem and OPC mortars are found to be 11.5mm and 10.1mm respectively at 28days. The sulfate resistance of Non-cem mortar is much higher than that of OPC (i.e., the reduction in compressive strength of Non-cem and OPC mortars were 12.6% and 14.1% respectively because of immersion in 5% magnesium sulfate solution after one month). In case of corrosion resistance, cracks are shown in OPC mortars earlier than Non-cem mortars and in case of thermal resistance of Non-cem mortars lose their strengths by 19.21% whereas OPC mortars lose their strengths by 32.87%. These test results indicate that Non-cem could be used as an alternative of cement.

ПОРІВНЯЛЬНА ОЦІНКА ВЕЛИЧИНИ АНТИАПОПТОТИЧНОГО ЕФЕКТУ СЕРЕД МОДУЛЯТОРІВ АКТИВНОСТІ NMDA-РЕЦЕПТОРІВ В УМОВАХ МОДЕЛЬНОЇ ПЕРЕХІДНОЇ ІШЕМІЇ РЕПЕРФУЗІЇ ОКА ЗА ДАНИМИ ПРОТОКОВО-ЦИТОМЕТРИЧНОГО АНАЛІЗУ

Модельна 60 хв. ішемія-реперфузія ока у щурів супроводжується активацією апоптотичних процесів в сітківці, про що достеменно свідчить збільшення в середньому в 20,22 раза пулу клітин, які перебувають у фазі SUB-G0G1, тобто мають ознаки фрагментації ядерної ДНК, що анонсує апоптоз. Однократна внутрішньовенна інфузія в лікувальному режимі через 30 хв після накладання лігатур розчинів амантадину або магнію сульфату, дозами 5 та 250 мг/кг відповідно, а також мемантин перорально з розрахунку 20 мг/кг, сприяють зменшенню відносної кількості ретиноцитів, які перебувають фазі SUB-G0G1 клітинного циклу, проявляючи тим самим антиапоптотичну дію. За спроможністю в умовах даної патології знижувати процес фрагментації ядерної ДНК, застосування розчину амантадину сульфату вірогідно переважає терапію розчином магнію сульфату або мемантином в середньому на 24,1 та 52,0 % відповідно.

防治七叶皂苷钠静滴后不良反应的护理体会

目的：观察艾条灸配合25%的硫酸镁液无菌湿敷辅与中医护理健康教育在防治七叶皂苷钠静滴后不良反应的临床效果。方法：将122例患者按编号随机分为对照组和研究组，对照组采用常规50%的温硫酸镁液湿敷并辅与中医护理健康教育，而研究组采用艾条灸配合25%硫酸镁注射液无菌湿敷并辅与中医护理健康教育。结果：研究组的患者在疗效、敷药次数、患者满意度及护理人员满意度方面明显优于对照组。结论：七叶皂苷钠静滴后出现的不良反应，应用艾条灸配合25%的硫酸镁注射液无菌湿敷，防治效果好。 Objective: To observe the clinical and adverse effect of seven sodium aescinate injection with moxa stick moxibustion, 25% magnesium sulfate solution wet compressing and Chinese medicine nursing health education. Methods: 122 patients were divided into control group and treatment group, and the control group was treated with normal 50% magnesium sulfate solution and treatment group was treated with 25% magnesium sulfate solution, both groups also took Chinese medicine nursing health education. Results: The efficacy, number of medication, satisfaction of patients and medical workers were better in treatment group significantly. Conclusion: With the adverse effect of seven sodium aescinate injection, moxa stick moxibustion and 25% magnesium sulfate solution wet functions better for treatment and prevention.

STUDY OF THE RESTORATION FEATURES OF SOILS THAT WERE INFLUENCED BY FORMATION WATERS

The article presents the studies results on the restoration of saline soils affected by formation waters. Soil restoration was carried out using solutions of various water-soluble salts. The author determined that treatment of saline soils with a solution of magnesium sulfate at a concentration of 0,3 mol/dm3 helps to decrease the content of chlorides, sodium, calcium, while the content of magnesium and sulfates increases, but the total content of toxic salts in the soil decreases by 60,9%.

Influence of Cement Type and Water-to-Cement Ratio on the Formation of Thaumasite

Cement mortar prisms were prepared with three different cement types and different water-to-cement ratios plus 30% mass of limestone filler. After 28 days of curing in water at room temperature, these samples were submerged in 2% magnesium sulfate solution at 5°C and the visual appearance and strength development for every mortar were measured at intervals up to 1 year. Samples selected from the surface of prisms after 1-year immersion were examined by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The results show that mortars with sulfate resisting Portland cement (SRC) or sulphoaluminate cement (SAC) underwent weaker degradation due to the thaumasite form of sulfate attack than mortars with ordinary Portland cement (OPC). A lower water-to-cement ratio leads to better resistance to the thaumasite form of sulfate attack of the cement mortar. A great deal of thaumasite or thaumasite-containing materials formed in the OPC mortar, and a trace of thaumasite can also be detected in SRC and SAC mortars. Therefore, the thaumasite form of sulfate attack can be alleviated but cannot be avoided by the use of SAC or SRC.

Activation Energy Parameters for Hydrodynamic Permeability of Binary Aqueous Solutions of Divalent Transition Metal Sulphates and Magnesium Sulphate Through an Inorganic Membrane of Aluminium Oxide

Activation Energy Parameters for Hydrodynamic Permeability of Binary Aqueous Solutions of Divalent Transition Metal Sulphates and Magnesium Sulphate Through an Inorganic Membrane of Aluminium Oxide

The effects of nano- and micro-particle additives on the durability and mechanical properties of mortars exposed to internal and external sulfate attacks

In this study, the effects of micro-silica (MS), nano-silica (NS), class C fly ash (FA), and metakaolin (MK) on the durability and mechanical properties of mortars exposed to internal and external sulfate attacks were investigated. For that purpose, mortars were produced from 3 different sands with different ratios of sulfate ions to generate conditions for an internal sulfate attack. Standard curing procedures were applied to all mortar samples for 23weeks. Furthermore, mortar samples prepared from Sand A, which had the lowest sulfate content, were kept in sodium sulfate and magnesium sulfate solutions to produce an external sulfate attack. When all test results were evaluated together, the most significant contribution to durability and strength among the admixtures was observed to be from NS, which demonstrated an average improvement of 2–10% over MS, which had the second most significant contribution for mortar samples exposed to the most severe internal and external sulfate attacks. When all mixing ratios and tests were considered, the least significant contribution to durability and strength was determined to be from metakaolin. Additionally, when the test data for all days were compared, magnesium sulfate was found to be approximately 1–10% more destructive in comparison to sodium sulfate.

Assessment of Mechanical Properties and Damage of High Performance Concrete Subjected to Magnesium Sulfate Environment

Sulfate attack is one of the most important problems affecting concrete structures, especially magnesium sulfate attack. This paper presents an investigation on the mechanical properties and damage evolution of high performance concrete (HPC) with different contents of fly ash exposure to magnesium sulfate environment. The microstructure, porosity, mass loss, dimensional variation, compressive strength, and splitting tensile strength of HPC were investigated at various erosion times up to 392 days. The ultrasonic pulse velocity (UPV) propagation in HPC at different erosion time was determined by using ultrasonic testing technique. A relationship between damage and UPV of HPC was derived according to damage mechanics, and a correlation between the damage of HPC and erosion time was obtained eventually. The results indicated that (1) the average increasing amplitude of porosity for HPCs was 34.01% before and after exposure to magnesium sulfate solution; (2) the damage evolution of HPCs under sulfate attack could be described by an exponential fitting; (3) HPC containing 20% fly ash had the strongest resistance to magnesium sulfate attack.

Effect of internal sulfate attack on the properties of sulfate-resisting cement and alkali-activated slag

This work aims at studying the effect of internal sulfate attack on the properties of sulfate-resisting cement (SRC) and alkali-activated slag (AAS). Blast-furnace slag was activated by 3% sodium hydroxide (NaOH) and 3% sodium silicate (Na2SiO3) by weight of slag. Magnesium sulfate (MgSO4) solution with concentration of 0, 4, 12, and 20 wt.% was mixed with AAS and SRC at water to cement ratio (W/C) of .25. The results showed that the AAS setting times decrease with MgSO4%. As the MgSO4% increases up to 12%, the SRC setting times are elongated, and then shortened at 20%. The compressive strength of SRC decreases with the increase of MgSO4%. In contrast, the AAS compressive strength increases with MgSO4% up to 12%, then decreases at 20%. Drying shrinkage reduction and increment were observed when SRC and AAS were mixed with MgSO4. These results were confirmed by X-ray diffraction, Fourier transformer infrared spectroscopy, and thermogravimetric (TG/DTG) analyses. The results proved that, the AAS can be beneficially used in cement concrete containing high sulfate concentration with better performance than SRC.

Deterioration of Travertine Samples Due to Magnesium Sulfate Crystallization Pressure: Examples from Iran

In order to assess the resistance of travertine against salt crystallization, 15 travertine samples were selected from Iran’s mines. Petrographic, physical and mechanical properties of the travertine samples were determined, and then salt crystallization test was carried out by using magnesium sulfate (MgSO4) solution up to 60 cycles. Dry weight increment, dry weight loss, Brazilian tensile strength (BTS), point load strength index and P-wave velocity were calculated at 10, 20, 30, 40, 50 and 60 number of cycles. Two weathering forms (granular disintegration, and alveolaring) were observed in the samples as a result of salt crystallization pressure. Onyx travertine samples were more resistant than travertine samples. It was found out that the deterioration rate at elementary cycles was lower. The results showed that durability of samples has a positive relationship with initial BTS and a negative relationship with initial effective porosity. It was concluded non-destructive tests are good technique for assessment of travertine deterioration in salt crystallization test.

Higher-order stimulated Raman scattering in an aqueous solution of magnesium sulfate pumped by 532 nm laser pulses

We report on the generation of higher-order stimulated Raman scattering (SRS) in a saturated aqueous solution of MgSO4, pumped by a 532 nm frequency-doubled Nd:YAG laser operating with multiple longitudinal modes. The first- (∼561.4 nm), second- (∼594 nm), and third-order (∼630 nm) Stokes components of SRS were observed, and were attributed to the symmetric vibrations of the [SO4] tetrahedral structural groups. Two possible physical mechanisms for generating higher-order SRS were analyzed. The results point to an efficient method for generating new laser wavelengths from a liquid blended media system through a higher-order nonlinear SRS process.

Influence of curing duration on thaumasite formation of Portland-limestone cement pastes

Extensive researches have been carried out on the conventional sulfate attack, while it has been found that the thaumasite form of sulfate attack (TSA), sulfate attack at low temperature, has just been discovered and its mechanism is not well understood so far. In this study, the sulfate attack of cement paste incorporating 30% mass of limestone powder was investigated. After 20 °C water cured for 7, 14, and 28 days, respectively, 20 mm cube specimens were exposed in a 5% magnesium sulfate solution at (6 ±1) °C for periods up to 240 days. Their appearance change, compressive strength development were examined at different storage time, and selected paste samples were examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results indicate that all Portland-limstone cement pastes suffer from appearance deterioration to some extent. The compressive strength of cement paste initially increases and after 120 days decreases with increasing exposed period. In addition, the cement paste with short curing time is more susceptible to sulfate attack, which directly leads to the formation of non-binder thaumasite crystal accompanied by the formation of ettringite, gypsum and brucite, and becomes a white, mushy, and incohesive matrix. Additionally, the extent of sulfate attack is greater and the formation of thaumasite is observed earlier for shorter curing time.

Inhomogeneity of the density of Parascaris spp. eggs in faeces of individual foals and the use of hypothesis testing for treatment decision making

Faecal egg counts (FEC) are used widely for monitoring of parasite infection in animals, treatment decision-making and estimation of anthelmintic efficacy. When a single count or sample mean is used as a point estimate of the expectation of the egg distribution over some time interval, the variability in the egg density is not accounted for. Although variability, including quantifying sources, of egg count data has been described, the spatiotemporal distribution of nematode eggs in faeces is not well understood. We believe that statistical inference about the mean egg count for treatment decision-making has not been used previously. The aim of this study was to examine the density of Parascaris eggs in solution and faeces and to describe the use of hypothesis testing for decision-making. Faeces from two foals with Parascaris burdens were mixed with magnesium sulphate solution and 30 McMaster chambers were examined to determine the egg distribution in a well-mixed solution. To examine the distribution of eggs in faeces from an individual animal, three faecal piles from a foal with a known Parascaris burden were obtained, from which 81 counts were performed. A single faecal sample was also collected daily from 20 foals on three consecutive days and a FEC was performed on three separate portions of each sample. As appropriate, Poisson or negative binomial confidence intervals for the distribution mean were calculated. Parascaris eggs in a well-mixed solution conformed to a homogeneous Poisson process, while the egg density in faeces was not homogeneous, but aggregated. This study provides an extension from homogeneous to inhomogeneous Poisson processes, leading to an understanding of why Poisson and negative binomial distributions correspondingly provide a good fit for egg count data. The application of one-sided hypothesis tests for decision-making is presented.

Sulfate Resistance of Alkali Activated Cements

One of the most important questions of concrete durability is increasing of corrosion resistance of cement stone and materials on his basis. Perspective way of solving such problems is using of alkali activated binders.Two cement systems were investigated to obtain different materials for different application - geocement system for repair materials and protective coatings and fly ash alkali activated hybrid cement for corrosion resistant common cements and concretes.It was studied sulfate resistance of fly ash alkali activated cements after 3 years of storing in aggressive environments like 5 and 10 % solutions of sodium sulfate, 2 and 4 % solutions of magnesium sulfate and sea salt solution. It was shown that fly ash containing cements are characterized by high corrosion resistance (coefficient of corrosion resistance after 3 years of storing in aggressive environment is in the ranges 0.8...1.0) comparing with clinker cements (0.45...0.88). Shown, that high sulfate resistance of cements under study in time is caused by graduate structure development and crystallization of new formations with compacting structure of material that effect on service properties of materials.High corrosion resistance of geocement compositions (coefficient of corrosion resistance 0.9-1.05) in sulfate environment is possible because of formation of faujasite, chabasite, mordenite and nozean phases in the structure of materials. Optimal composition of geocement compositions were developed according mathematical planning of experiments and tested.

Fly Ash Slag Geopolymer Concrete: Resistance to Sodium and Magnesium Sulfate Attack

AbstractThis study evaluated the performance of geopolymer concretes based on a binary mixture of fly ash (FA) with blast furnace slag (GBFS) in an 80/20 ratio and activated with a mixture of sodium silicate and sodium hydroxide. FA/GBFS and portland cement (OPC) concretes were immersed in 5% by weight sodium sulfate and magnesium sulfate solutions. Volumetric expansion and mechanical resistance loss were measured, and the reaction products were characterized by X-ray diffraction and scanning electron microscopy. The highest levels of deterioration were found in the probes exposed to MgSO4, indicating the higher aggressiveness of this solution. After aging for 360 days in MgSO4, the FA/GBFS concrete expanded by 0.04% and decreased its mechanical resistance by 33%, compared to 0.08 and 48%, respectively, for similarly treated OPC concretes. However, the same exposure to Na2SO4 increased the observed FA/GBFS resistance while reducing the mechanical resistance of OPC by 30%. This relates to their respective ...