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Optimization of a Modified QuEChERS Method of Experimental Design for Vitamin B2, B3, B6 and B9 in Powder Formula Milk by HPLC/DAD Thi, Ngoc-Van Nguyen; Duong, Ngan Tuyet; Pham, Thanh Tuan; Duong, Chau Ngoc; Thi, Cam-Thuy Le; Pham, Kieu Bich; Nguyen, Kien Trung
Science and Technology Indonesia Vol. 9 No. 4 (2024): October
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2024.9.4.893-903

Abstract

The purpose of this work is to use HPLC/DAD to ascertain the best extraction and cleanup conditions for various forms of vitamin B in powder formula milk. The QuEChERS method’s key variables were optimized using a Box-Behnken design with 3-level 4-variable and Minimum-Run Resolution IV Screening Design. Following the selection of the best experimental setup, the suggested approach was applied to quantify four vitamins B (B2, B3, B6, and B9) in powder formula milk matrix by HPLC/PDA in accordance with AOAC and ICH guidelines. When taking into account the performance standards given in this guideline, the approach presented recovery between 83.55 and 108.43 for 4 B vitamins, which is adequate. The intra-day and inter day percentage relative standard deviations were 1.66 to 2.75% and 0.47 to 4.78%, respectively. Furthermore, the technique enabled the determination of low detection limits in less than 25 minutes of analytical time. The proposed method’s excellent accuracy, precision, and efficiency made it acceptable for regular B vitamin analysis when applied to powder formula milk samples. The findings confirmed that the modified QuEChERS technique is appropriate for routinely assessing B vitamin levels in powder formula milk matrix.
Consolidation Behavior of Soft Soil Treated with PVDs and Vacuum-Surcharge Preloading Le, Nghia Trong; Nguyen, Kien Trung; Nguyen, Minh Trung
Civil Engineering Journal Vol. 11 No. 7 (2025): July
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2025-011-07-024

Abstract

Prefabricated vertical drain (PVD) combined with vacuum-surcharge preloading is a widely used ground improvement technique to accelerate the dissipation of excess pore water pressure and reduce the soil compressibility. However, difficulties in the numerical simulations of water dissipation and equivalent permeability of soil with PVDs in three-dimensional (3D) and two-dimensional (2D) settings cause substantial deviation of numerical results from observational data. Moreover, the optimum length of PVDs has not been well documented. Accordingly, this work analyzes a project in Dong Nai, Vietnam, where a 37-meter-thick soft soil was treated with PVDs and vacuum-surcharge preloading. In this work, the field observations and finite element method with consolidation theory were used to analyze the ground settlements, lateral displacements, and excess pore water pressure. The observed and simulated data shows that (i) the rate of settlements in the first 60 days of increasing preloading pressure is about 2.1 times faster than that in the next 110 days of constant preloading pressure, (ii) at 170 days, the ground-surface lateral displacement at the toe of the embankment is around 50 mm and reaches its maximum value of 150 mm at 1.55 m depth, and (iii) the dissipation of pore water pressure is closely correlated with the settlement rate. Moreover, back analysis indicates that a permeability conversion ratio from 1.872 to 4.538 should be applied to achieve the same degree of consolidation between 3D and 2D models. Lastly, the optimum length of PVDs in this project is 28 m, around 76% of the fully penetrated length into the soft layer.
Effect of Spatial Variability of Soil Shear Strength on the Displacement of an Axially Loaded Pile Le, Dung Van; Nguyen, Kien Trung
Civil Engineering Journal Vol. 12 No. 3 (2026): March
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2026-012-03-02

Abstract

This manuscript studies the influence of spatial heterogeneity in soil effective cohesion c' on the displacement of an axially loaded pile under static compression. The Monte Carlo method was used to perform statistical evaluation, while the K-Means clustering technique was employed to reduce the necessary number of simulations without compromising the accuracy and reliability of the analysis results. In this study, a two-dimensional correlated random field of c' was generated using the spectral method, assuming a Gaussian distribution with a coefficient of variation of 10%. The spatial correlation lengths of the scaled model were set to 80 mm and 19.4 mm in the horizontal and vertical directions, respectively. The static pile loading process was simulated using the finite element method implemented in the commercial software PLAXIS, with six loading stages ranging from 20 N to 120 N. The influence of soil effective cohesion randomness on pile displacements was evaluated based on statistical data obtained from the numerical simulation of 1000 realizations of random fields. The generated correlated random fields were verified to follow a normal distribution. Meanwhile, the pile displacements at different loading levels tend to follow normal distribution as well, except at the 40 N loading stage, where a deviation from normality was observed. Compared with the homogeneous soil model with a mean value of c', up to 63% of the simulation cases exhibit pile displacement exceeding the allowable limit. Moreover, the effectiveness of the K-means clustering technique in reducing the number of required realizations, and thus the computational workload, was evaluated. The pile displacement results show that when the number of representative clusters reaches 100 or more, the subset data cover more than 98.2% of the full data set, i.e., data from 1000 realizations.