Articles
Publication Date: 2024
Optical Materials (09253467)148
We report on the nonlinear properties of the series of deep eutectic solvents (DESs) which are prepared by a certain ratio of choline chloride as the base and lactic acid as additive materials. The z-scan technique is used to characterize the nonlinear index and absorption of the solvents. Obtained results indicated a negative nonlinear index of the order of about 10−9 cm2/W for the DES solvents at 808 nm of a ∼60-mW CW laser source. It is further found that while the different ratios of lactic acid are increasingly added to the choline chloride, the nonlinear index of solvents are accordingly changed by a factor of 1.2 in magnitude. The results of the open-aperture z-scan confirmed that neither the solvents nor the lactic acid responded to the nonlinear absorption. The represented experiment suggested that with a novel look at these series of DES liquids, it is possible to improve their nonlinear properties by engineering the ratio of choline chloride and lactic acid. © 2024 Elsevier B.V.
Publication Date: 2023
Journal of Chemometrics (08869383)37(1)
In this study, the effect of different error structures on psedounivariate and multivariate analytical figures of merit in simulated data of hyphenated chromatographic systems was investigated. Different error structures (e.g., homoscedastic, heteroscedastic, and correlated) were investigated. For this purpose, five components systems at five concentration levels with three replicates were simulated. Different types of error were added to the data. Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) and Maximum Likelihood Principal Component Analysis (MLPCA-MCR-ALS) methods were used. After resolution, pseudo-univariate and multivariate analytical figures of merit were calculated and compared. As it expected, the detection limit for noisy datasets is higher than the noise-free datasets, whereas the slopes of the calibration curves are not significantly different. Comparing the results generally showed that the detection limit values in multivariable mode were better than the univariate mode. The LODs of data (pseudo-univariate and multivariate) with homoscedastic and correlated error structure by MCR-ALS and MLPCA-MCR-ALS were the same. The analysis of data with heteroscedastic error structure by MLPCA-MCR-ALS had a lower detection limit than analysis with MCR-ALS. The figures of merit obtained from WLS and OLS regression in heteroscedastic datasets were compared and better LODs were obtained after WLS method. © 2022 John Wiley & Sons Ltd.
Saeidi, H.,
Mozaffari, M.,
Ilbey, S.,
Dutz s., S.,
Zahn d., D.,
Azimi gandomani, G.,
Bock, M. Publication Date: 2023
Nanomaterials (20794991)13(2)
Magnetic nanoparticles (MNPs) have been widely applied as magnetic resonance imaging (MRI) contrast agents. MNPs offer significant contrast improvements in MRI through their tunable relaxivities, but to apply them as clinical contrast agents effectively, they should exhibit a high saturation magnetization, good colloidal stability and sufficient biocompatibility. In this work, we present a detailed description of the synthesis and the characterizations of europium-substituted Mn-Zn ferrite (Mn0.6Zn0.4EuxFe2-xO4, x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.15, herein named MZF for x = 0.00 and EuMZF for others). MNPs were synthesized by the coprecipitation method and subsequent hydrothermal treatment, coated with citric acid (CA) or pluronic F127 (PF-127) and finally characterized by X-ray Diffraction (XRD), Inductively Coupled Plasma (ICP), Vibrating Sample Magnetometry (VSM), Fourier-Transform Infrared (FTIR), Dynamic Light Scattering (DLS) and MRI Relaxometry at 3T methods. The XRD studies revealed that all main diffraction peaks are matched with the spinel structure very well, so they are nearly single phase. Furthermore, XRD study showed that, although there are no significant changes in lattice constants, crystallite sizes are affected by europium substitution significantly. Room-temperature magnetometry showed that, in addition to coercivity, both saturation and remnant magnetizations decrease with increasing europium substitution and coating with pluronic F127. FTIR study confirmed the presence of citric acid and poloxamer (pluronic F127) coatings on the surface of the nanoparticles. Relaxometry measurements illustrated that, although the europium-free sample is an excellent negative contrast agent with a high r(2) relaxivity, it does not show a positive contrast enhancement as the concentration of nanoparticles increases. By increasing the europium to x = 0.15, r(1) relaxivity increased significantly. On the contrary, europium substitution decreased r(2) relaxivity due to a reduction in saturation magnetization. The ratio of r(2)/r(1) decreased from 152 for the europium-free sample to 11.2 for x = 0.15, which indicates that Mn0.6Zn0.4Eu0.15Fe1.85O4 is a suitable candidate for dual-mode MRI contrast agent potentially. The samples with citric acid coating had higher r(1) and lower r(2) relaxivities than those of pluronic F127-coated samples.
