Effects of Disodium Hydrogen Phosphate Addition and Heat Treatment on the Formation of Magnesium Silicate Hydrate Gel

The formation of magnesium silicate hydrate gel is crucial in preventing magnesia aggregates from over hydrated during the construction of refractory castables since the presence of magnesium hydroxide diminish the mechanical properties of the material. This work aimed to investigate the accelerating effects of sodium hydrogen phosphate and heat treatment on the formation of magnesium silicate hydrate gel. Time-dependent pH of magnesia - silica fume slurries with and without sodium hydrogen phosphate addition and heat treatment was measured to verify the dissolution of MgO and magnesium silicate hydrate formation. The effects of sodium hydrogen phosphate were differentiable only at small added amounts, whereas heat treatment at 50 degrees Celsius performed noticeable acceleration. This observation could be applicable in molding to maintain the stability of basic refractory castables.

The Effect of Liquid Phase Concentration on the Setting Time and Compressive Strength of Hydroxyapatite/Bioglass Composite Cement

Composite scaffolds of hydroxyapatite (HAp) nanoparticles and bioactive glass (BG) have been applied as appropriate materials for bone tissue engineering. In this study, hydroxyapatite/bioglass cement in different ratios was successfully fabricated. To prepare HAp and HAp/BG cement, synthesized HAp and HAp/BG powder were mixed in several ratios, using different concentrations of sodium hydrogen phosphate (SP) and water as the liquid phase. The liquid to powder ratio used was 0.4 mL/g. The results showed that setting time increased with BG content in the composite. The results also showed that with the addition of bioglass to the HAp structure, the density decreased and the porosity increased. It was also found that after immersion in simulated body fluid (SBF) solution, the compressive strength of the HAp and HAp/BG cements increased with BG concentration up to 30 wt.%. SEM results showed the formation of an apatite layer in all selected samples after immersion in SBF solution. At 30 wt.% BG, greater nucleation and growth of the apatite layer were observed, resulting in higher bioactivity than pure HAp and HAp/BG in other ratios.

A Novel UPLC Method for Simultaneous Estimation of Ertugliflozin and Sitagliptin in Bulk and Tablet Dosage Form

Aim: The proposed study aimed to develop a novel ultra-performance liquid chromatography (UPLC) method for the estimation of Ertugliflozin and Sitagliptin in Bulk and Tablet dosage form and validate the method in accordance with the International Conference on Harmonization guidelines. Methods: The optimized conditions for the developed UPLC method are Acquity UPLC HIBRA C18 (100mm × 2.1mm, 1.8µ) column maintained at 30°C with a mobile phase consisting of Buffer (0.01N sodium hydrogen phosphate) pH adjusted to 4.0 with dil. orthophosphoric acid: Acetonitrile in the ratio of 60:40%v/v on isocratic mode at a flow rate of 0.3mL/min. Results and conclusion: The sample was detected at 220nm. The retention time for Ertugliflozin and Sitagliptin was deemed at 1.873min and 1.260min. The developed method was validated for accuracy, precision, specificity, ruggedness, robustness, and solution stability. The method obeyed Beer’s law in the concentration range of 3.75µg/mL to 22.5µg/mL for Ertugliflozin and 25µg/mL to 150µg/mL for Sitagliptin with a correlation coefficient of 0.999 for Ertugliflozin and Sitagliptin respectively. Forced degradation studies were conducted by exposing the drug solution to numerous stress conditions such as acidic, basic, peroxide, neutral, photolytic, and thermal conditions. The net degradation was considered within the limits, indicating that the drug is stable in stressed conditions. The developed method for the estimation of Ertugliflozin and Sitagliptin can be utilized for the routine analysis of Pharmaceutical dosage form.

Comparative study of atenolol in human plasma by high performance liquid chromatography and capillary zone electrophoresis

Atenolol is a beta-blocker that is cardioselective, meaning it only affects beta receptors. It is used to treat angina pectoris and high blood pressure. The HPLC and Capillary Zone Electrophoresis analytical technique was developed for the purpose of detecting and quantifying Atenolol in human plasma, according to the study paper you're reading right now. The internal standard and atenolol were recovered from the solution after being extracted from plasma using the Liquid-Liquid Extraction method. A mobile phase of 10mM sodium hydrogen phosphate, 7.3mM Sodium Lauryl sulphate (pH=3), methanol, and acetonitrile (40:57:3, v:v:v) is used, with a flow rate of 1.0ml/min. A fluorescence detector was used to detect the isolated materials, which had an excitation wavelength of 229 nm and an emission wavelength of 298 nm. With this in view, Atenolol's and the internal norm's survival times are observed to be 5.4 and 8.3 minutes, respectively. The linear correlation coefficient (R20.9992) was found in the Atenolol calibration curve. The recovery rate for atenolol and an internal norm was estimated to be between 76 and 87 percent. Solid-phase extraction was performed on an uncoated silica capillary with a diameter of 58.5 cm 75 m, and detection was performed at 194 nm in the Capillary Zone Electrophoresis procedure. For an electrolyte solution containing 50mM H3BO3 and 50mM Na2B4O7 (50:50 V/V), atenolol was determined to be present in the solution in less than 3 minutes. Energized with a voltage of 25kV and injected with a hydrodynamic configuration for 4S. Under various conditions, this method was used to assess the stability and capability of measuring Atenolol in human plasma.

Bioanalytical Method Development of Atenolol Enantiomers: Stereoselective Behavior in Rabbit Plasma by RP-UFLC Method

Objective: The objective of the method was to develop a new, simple and reliable enantioselective Reverse Phase- Ultra Fast Liquid Chromatography (RP-UFLC) method for the separation of Atenolol enantiomers. Comprehensive study was performed by extending the work to pharmacokinetic studies using rabbit plasma. Background: Many methods were reported for enantioseparation of Atenolol enantiomers but, no attempts were made for chiral separation of Atenolol using rabbit plasma. Moreover, pharmacokinetic data to prove the efficiency of particular enantiomers in rabbit plasma was not studied. Method: In the present examination, the binary RP-UFLC technique was developed on Phenomenex® Lux cellulose i5 segment (150×4.6 mm, 5µ) using di-sodium hydrogen phosphate buffer (pH 6.8): acetonitrile (35:65 v/v) as the mobile phase. Results: The elution of Atenolol was observed at 225 nm with a stream rate of 1 mL.min-1. The described technique offered a linear relationship with a regression coefficient of r2= 0.997 and 0.996 for (R) and (S)-enantiomer respectively between the concentration range of 2-10 ng.mL-1. Atenolol enantiomers were detected at a retention time (tR) of 2.7 min and 3.10 min R and S-enantiomer respectively. The rate of recovery of both Atenolol enantiomers was observed to be (R) 98.18% and (S) 100.45% individually. USFDA guidelines May 2018, were systematically followed for bioanalytical method development and validation. Conclusion: The developed technique was applied for the separation of Atenolol enantiomers and for the pharmacokinetic determination of Atenolol enantiomers in rabbit plasma.

ПРИДАНИЕ ОГНЕЗАЩИТНЫХ СВОЙСТВ ЦЕЛЛЮЛОЗНЫМ ТЕКСТИЛЬНЫМ МАТЕРИАЛАМ С ПРИМЕНЕНИЕМ ЗОЛЬ - ГЕЛЬ ТЕХНОЛОГИИ

The article presents studies on the use of a new composition based on sodium silicate, urea and sodium hydrogen phosphate to impart fire-retardant properties to cellulosic textile materials. The influence of the concentration of the starting components, temperature, and heat treatment time on the flame retardant properties was studied. The change in the fire retardant properties of cotton fabric is given for three heat treatment modes: at 80, 90 and 100 °C. Compared to the initial fabric, the samples treated with a flame retardant have indicators of flame retardant properties. Untreated fabric with a size of 220×170 mm when tested for flammability at an ignition time of 15 s completely burns out in 60 s. In samples treated with a flame retardant, at an ignition time of 15 s, the smoldering time is practically reduced to zero. With an increase in the concentration of the flame retardant, and the temperature of the heat treatment, the loss of material strength, breaking load, and the appearance of the fabric change slightly. Using electron scanning microscopy and energy dispersive microanalysis, it was shown that pure cotton fabric contains 68.77% carbon and 31.22% oxygen; after modification, particles of sodium – 0.02%, phosphorus – 0.04% and potassium – 0.05% are formed on the surface of the treated fabric. distributed fairly unevenly. It has been shown that in cellulosic materials modified with compositions based on sodium silicate and urea, sodium hydrogen phosphate, flame retardant properties increase. The proposed composition provides the achievement of higher fire resistance. Processing can be carried out on standard equipment of finishing enterprises without the stage of high-temperature fixation of the drug.