Papers by Keyword: Validation

Abstract: Lattice boltzmann method (LBM) has emerged as a powerful numerical technique for simulating fluid flows due to its inherent simplicity and efficiency. In this paper we studied a convective heat transfer occurring naturally within a cubic enclosure differentially heated filled with air (Pr=0.71) to compare the obtained results with those obtained from the literature. For this a fortran code program utilized for simulating natural convective phenomena in two and three dimensions (2d and 3d LBM) considerate a single relaxation time LBM (SRT-LBM). The results are presented in terms of isotherms, velocity and average nusselt number. The verification of the lattice boltzmann method code shows a good agreement with the literature.

Abstract: Colorimetry is an analytical method based on the visualization of color changes. This method is simple, inexpensive, and efficient so that it can be applied to detect dissolved ferrous metal ions in the form of Fe (II). Fe (II) ions can form complex compounds with 1,10-phenanthroline ligands in carrageenan matrices of iota and kappa types made in the form of beads. In this study, interference testing and method validation have been conducted to optimize and evaluate beads in the colorimetric detection of Fe (II). The results exhibited that Ni (II) and Cu (II) ions as interferents lowered the color intensity of the complex compound of Fe (II) with 1,10-phenanthroline at concentrations starting from 10 mg/L. Besides, Fe (III) improved the colorimetric detection color intensity from the lowest concentration of 3 mg/L, while Mg (II), at 25 mg/L, decreased the color intensity. Furthermore, the standard curve exposed good linearity. Based on the standard deviation and the standard curve slope, the beads limit in the colorimetric detection of Fe was 0.17 mg/L. The quantification limit obtained through calculations was 0.57 mg/L. The precision could be considered good. The beads interference test for colorimetric detection of Fe (II) had good accuracy with a recovery value of 93-102%. Keywords: Bead, Colorimetric Detection, Validation, Interference Test

Abstract: Caffeine, an alkaloid compound found in coffee, is widely known for its ability to stimulate the human central nervous system. The caffeine content in Sidomulyo robusta coffee was analyzed using a gas chromatography-flame ionization detector (GC-FID) with ultrasound-assisted extraction as a preparation method using methanol solvent for 21 minutes at 32°C. A TR-1MS column (15m x 0.25 mm ID x 0.25 μm film, non-polar column 100% dimethyl poly-siloxane) was used for the GC analysis. The injector temperature was set at 260°C and the detector at 280°C. The initial oven temperature was set at 100°C, held for 1 minute, then gradually increased by 5°C/minute up to 280°C and held for 2 minutes, with the optimal flow rate condition selected at 1.2 mL/min. This method met all verification criteria and exhibited linearity in the 100–600 mg/L range with a high correlation coefficient of 0.9929, demonstrating its reliability and accuracy in determining caffeine content in coffee samples

Abstract: The aim of this work was to develop and validate RP-HPLC method for quantification of 4 major polyphenolic compounds of mulberry leaf infusion. The mulberry leaf samples were extracted by simulation of tea infusion beverage preparation. HPLC-DAD analysis combined with column C-18 150 mm x 4.6 mm, 2.7 μm was used to determine bioactive polyphenols such as chlorogenic acid, caffeic acid, rutin, and quercetin. The optimal conditions involved the flow rate of mobile phase at 0.3 ml/min with gradient elution of 0.1% formic acid in water and methanol, column temperature at 35 °C, 2 μl injection volume, and the detection wavelength at 320 nm (chlorogenic acid and caffeic acid) and 360 nm (rutin and quercetin). The retention times of chlorogenic acid, caffeic acid, rutin, and quercetin were 25.68, 28.03, 33.97 and 39.11 minutes, respectively. Analysis of four bioactive compounds was found to be linear with a correlation coefficient > 0.99 each at the tested concentration. All other validation parameters that represented accuracy and precision met the AOAC requirements. The developed analytical method was specific, robust, and accurate for simultaneous determining the stated compounds in mulberry leaf extracted with hot water. Moreover, this method could provide the chromatographic profiles of specific cultivar from specific source that could be used to control the quality of mulberry leaf tea products. Different cultivars and different origins of mulberry leaf in this study were also found to present different content of chlorogenic acid, caffeic acid, and rutin. No quercetin was found in the studied samples.

Abstract: The development of acids digestion method without heating has been done. This research was conducted by comparing the result of wet acids digestion method without heating by using Teflon method compared with international standard methods, namely US-EPA 3050b and ISO 14869-1 methods. Variations of acid or acid mixtures are performed which are sulfuric acid, a mixture of nitric acid with hydrochloric acid (aqua regia), and a mixture of nitric acid with sulfuric acid (sulfonitrate acid). The results of the digestion were analyzed using atomic absorption spectrophotometer (AAS). Method of validation was conducted by determination of linearity, precision value, limit of detection and limit of quantification. Validation of Teflon method has been done by comparing the results of Teflon method with US-EPA 3050b and ISO 14869-1 with t-test and ANOVA for each variation of the same acid or mixtures of acids. Based on the precision test, all the acid digestion treatment for the soil samples (both single and mixed acids) produced low precision of Teflon method compared to US-EPA and ISO methods. In addition, t-test and ANOVA (F-test) showed that there is significant difference in the results of digestion data analysis of the Teflon method with international standard method. The shaking time variation for the Teflon method produced significant result in nickel concentration.

Abstract: UV-Vis spectrophotometric method was validated for the stability assessment of 5% extemporaneous vancomycin eye drops in different vehicles. The eye drops were extemporaneously prepared by dissolving vancomycin in various vehicles, including sterile water for injection (SWI), 0.45% normal saline (0.45%NSS) and artificial tear. The solutions were stored at room temperature and in refrigerator for 30 days. The content of vancomycin was measured by UV-Vis spectrophotometer at 280 nm. UV-Vis Spectrophotometric method was validated according to ICH guideline. The results indicated that the method was precise and accurate. The calibration curve was linear with r² = 0.9997 in the range of 40-160 μg/mL. LOD and LOQ were 3.39 and 10.26 μg/mL, respectively. The results showed that the percentage of vancomycin residual concentation in SWI and 0.45%NSS was decreased to less than 90% after storage at room temperature for 8 days, whereas the residual concentration of vancomycin in artificial tear was less than 90 % after 10 days in room temperature. Meanwhile the percentage of vancomycin residual concentation in all formulations was remarkably decreased to less than 90% after storage in refrigerator for 17 days. The physical appearance of eye drops in artificial tear remained unchanged. However the observed color of other formulations was gradually changed to yellow in day 7 at room temperature and day 17 in refrigerator. The pH values of all preparations were within the general U.S. pharmacopeia national formulation range of 2.5-4.5. In conclusion, the eye preparations of 5%w/v vancomycin in all selected vehicle were stable for 17 days in refrigerator (2-8°C).

Abstract: An ion chromatographic method for determination of bromide and bromate in the presence of standard anions in drinking water was described. The method was based on separation on Metrosep A Supp 7-250 (250 x 4 mm) column with 3.6 mmol/L Na₂CO₃ as eluent and conductivity detection after sequential chemical and carbon dioxide suppression. The influence of flow rate and column temperature was studied and optimal experimental conditions for simultaneous determination of eight anions were chosen. Analytical characteristics of the ion chromatographic method were assessed for simultaneous determination of bromide, bromate, fluoride, chloride, nitrate, nitrite, phosphate and sulfate. The calibration curves were linear (r²=1, N=7) in the concentration ranges: 0.4-12 mg/L BrO₃^- and 0.3-11 mg/L Br^-. Recovery test was performed on a spiked certified reference material for soft drinking water. The obtained recoveries for bromate and bromide were 96.0 and 101.0 %, respectively. The repeatability and intermediate precision were between 5.1 and 0.14 % (RSD) depending on the analytes concentration. The limits of detection were 20 μg/L BrO₃^- and 10 μg/L Br^-

Abstract: Construction investments are sensitive to time and cost overruns. Delay and cost escalation are considered two threats to project success. The project objective is to develop a model to predict project cost and duration based on historical data of similar projects. Statistical regression models are developed using real data of building projects. The methodology is adopted in 3 steps: a) Data collection b) Statistical analysis using Statistical Package for Social Sciences (SPSS) software c) Interpretation of results. The real data of cost and duration of 51 building projects have been collected. In statistics, regression analysis is a statistical process for estimating the relationships among variables. It includes many techniques for modelling and analyzing several variables, when the focus is on the relationship between a dependent variable and one or more independent variables. The analysis is done using SPSS developed by IBM Corporation. The Regression models have been developed using the data collected from Noel Builders, Kakkanad, Ernakulam to predict the project cost and duration. The developed models are validated using split sample approach. The model outputs can be used by project managers in the planning phase to validate the scheduled critical path time and project budget.

Abstract: Background: While treatment monitoring of healthcare interventions is mainly conducted at the hospital, most information on a patient’s health status could be obtained from his everyday life activities. Therefore, there is a great interest in methods for long term (home) monitoring applications. However, there is still a lack of quantitative methods allowing everyday life activities monitoring such as gait analysis at home. While video-based systems have been employed given their high accuracy, they remain expensive and obtrusive with the range of motion of a patient limited to the set up measurement volume. Body worn sensors on the other hand present as an excellent opportunity to remotely and unobtrusively monitor gait characteristics not only at home, but during activities of everyday life. Technical limitations as well as changes in the patient’s gait patterns challenge the extraction of specific gait parameters. Methods: We propose a hybrid system comprising of a markerless video-based motion capturing system and a wearable sensor system with foot worn sensors. A study protocol is presented that will be used to validate the systems against each other. Discussion: This study will evaluate whether a markerless motion capturing system is feasible as a complementary tool for everyday gait analysis. Further, we will validate the accuracy of the sensor system using the video-based system as a gold standard. In the future, the combination might allow a recalibration of algorithmic sensor parameters based on deviations from the reference video-based system, and the combination of both modalities may enhance gait analysis in home monitoring.

Abstract: The problem described in the paper concerns the thermo-physical properties of the green mould material to which the cast iron is most often poured. The study includes the experiment of pouring the cast iron plate into green bentonite-sand mould. The temperature fields of casting and in different zones of the mould were recorded. The goal of the study was to determine the substitute thermo-physical properties of mould sand containing the over-moisture zone by means of simulation tests (inverse problem). An originality of the related research is an attempt to take into account the effects of the global thermal phenomena occurring in the quartz sand bonded by bentonite-water binder, by application of the substitute thermal coefficients without using the coupled modeling. In the simulation tests in order to achieve the effect of rapid heating of the mould (below temperatures 100 °C) by poured cast iron (T>1300 °C), the function of the latent heat source and the modified values of substitute thermal conductivity and substitute specific heat of the molding sand were used. In order to facilitate the solution, the mould was divided into zones, in which different starting humidity of molding sand was assumed.