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This work aimed to develop a simple and rapid spectrophotometric method for the analysis of erythromycin in pharmaceutical dosage forms. Direct UV and first derivative measurements at the wavelengths of 285 and 300 nm, respectively, in combination with standard addition method gave promising results. In both techniques, methanol was used as a solvent and dibasic potassium phosphate buffer (pH 8) was used to hydrolyze erythromycin stearate to erythromycin. Both the direct UV and first derivative measurements using standard addition method illustrated excellent linearity in the concentration range of 3-15 mg/mL (r2 > 0.98 and > 0.99, respectively) with good precision (%RSD < 0.65%). The limits of detection (LOD) of direct UV and first derivative measurements were 0.08 and 1.37 mg/mL, respectively, and the limits of quantitation (LOQ) were 0.24 and 4.17 mg/mL, respectively. However, the first derivative measurement showed better % mean recovery (97.6% and 106.5% for brand A and B, respectively, %RSD < 3.34%) than the direct UV measurement (66.03% and 43.80% for brand A and B, respectively, %RSD up to 47.39%). Thus, the first derivative measurement using standard addition method was valuable for analyzing erythromycin in dosage forms, which excipients strongly interfere the UV absorbance of the drug.

Abstract Context The relationship of maternal and infant 25-hydroxyvitamin D concentration [25(OH)D] with infant growth is unclear. Objective Our objective was to explore whether 25(OH)D in pregnancy, umbilical cord blood (UCB), or in infancy was associated with infant growth. Design This study involved 798 healthy infants and their mothers in Finland. We assessed 25(OH)D during pregnancy, from UCB at birth, and from the infant at the age of 12 months. Main Outcome Measures Infant length, weight, length-adjusted weight, and head circumference at 6 and 12 months and midupper-arm circumference at 12 months. Results Of the mothers and infants, 96% and 99% were vitamin D sufficient [25(OH)D ≥50 nmol/L], respectively. Mothers with pregnancy 25(OH)D >125 nmol/L had the shortest, lightest (in weight), and thinnest (in length-adjusted weight) infants at 6 months (P for all < 0.05). For each 10 nmol/L higher UCB 25(OH)D, the infants were 0.03 SD score (SDS) shorter at 6 months (95% CI −0.05 to −0.01), adjusted for birth size, infant 25(OH)D, and parental height. Higher UCB 25(OH)D associated with smaller head circumference at 6 and 12 months (P for all <0.05) but attenuated after adjustments. Mothers with pregnancy 25(OH)D >125 nmol/L had the thinnest infants at 12 months (P = 0.021). For each 10 nmol/L higher infant 25(OH)D, the infants were 0.03 SDS lighter (−0.05 to −0.01) and 0.03 SDS thinner (−0.05 to 0.00) at 12 months. Conclusions Our results suggest that high pregnancy, cord blood, and infant vitamin D concentration may have disadvantageous effects on infant growth. We investigated the effect of 25-hydroxyvitamin D concentration in pregnancy, cord blood, and infancy on postnatal growth and found that higher vitamin D status predicts slower infant growth.

The computer-aided cooling curve analysis (CA-CCA) was employed to investigate the solidification behavior of Al-Ce-Mg-xCe ( x  = 0, 0.5, 1.0, 1.5, and 3.0 mass %) alloys. Field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques were used, along with the liquidus projection of ternary Al-Cu-Mg and Al-Cu-Ce phase diagrams, to evaluate the microstructure and predict the sequence of main reactions involved in the solidification of alloys. According to the results, Al 2 CuMg, Al 2 Cu, Al 15 (CuFeMn) 3 Si 2 , and Mg 2 Si were found to be the main compounds present in the microstructure of Al 2024 alloy. The addition of Ce up to 1.5 mass % resulted in the formation of AlCeCuSi, Al 8 CeCu 4 , and Al 24 Cu 8 Ce 3 Mn compounds in the microstructure. Further addition of Ce up to 3.0 mass % promoted the formation of a new Ce-rich phase (Al 4 Ce) in the microstructure. The formation temperature (range) and reactions during which the Ce-rich compounds are formed were also suggested. The formation of Al 4 Ce compound in the microstructure of 3 mass % Ce-containing samples suppressed the nucleation and growth temperatures of the Al 2 Cu eutectic, prolonged the solidification time, significantly reduced the solidification end temperature, and increased the alloy solidification range.

This work demonstrates simple and reliable spectrophotometric methods for the simultaneous determination of paracetamol (PAR) and meloxicam (MEL) in mixture I as well as PAR and domperidone (DOM) in mixture II in bulk form and laboratory-made tablets. Successful determination of mixture I was accomplished using direct zero-order spectrophotometry at 361 nm for MEL and first-order derivative ( 1 D) spectrophotometry by measuring the peak at 342 nm and the trough at 262 nm for MEL and PAR respectively. On the other hand, a ratio difference method was suggested for the analysis of mixture II. The difference between the ratio spectra amplitudes at 256 and 288 nm were recorded for PAR determination, and 216 and 288 nm for DOM quantitation using 50 µg/mL DOM and PAR respectively as divisors. The efficacy of the proposed procedures was assessed using ICH criteria for linearity, ranges, precision, accuracy, detection, and quantitation limits. With regard to mixture I, the calibration curves showed linearity in the ranges of 3–30 µg/mL for MEL (zero-order method) and 2.5–30 and 3–15 µg/mL for MEL and PAR, respectively (first-order method), with correlation values of at least 0.9991.Whereas for mixture II, with correlation coefficients of 0.9999, the calibration curves for PAR and DOM were linear in the ranges of 3–70 and 2.5–15 µg/mL, respectively.The established procedures were used to analyze the combinations in the lab-prepared pills, and assay results were compared with reported methods. Greenness of the devised spectrophotometric procedures was assessed using the Analytical Eco-Scale and the Analytical Greenness metric (AGREE).

Formoterol fumarate dihydrate ( FFD ) is a long-acting β 2 agonist, while Fluticasone propionate ( FP ) is a synthetic glucocorticoid receptor agonist. Both are used to manage chronic asthma and chronic obstructive pulmonary disease. The objective of this work is the quantitative analysis of the two drugs concurrently in their pure raw powder and medication dosage form, synthetic laboratory mixtures by three simple, precise, sensitive, and accurate spectrophotometric techniques operating on ratio spectra with the advantages of low-cost, high sensitivity, and no previous separation. Method (I) is based on the ratio subtraction method, which allows FP to be determined without the interference of FFD at its λ max of 236 nm. Method (II) is the first derivative of the ratio spectra, which enabled the measurement of peak amplitude of D 1 spectra at 233.2 nm for FP and 301.0 nm for FFD. Method (III) is the ratio difference spectrophotometry, where the difference in values between (214.4 and 236.0 nm) was calculated for the determination of FP; and the difference of peak amplitudes at 270.0 and 290.0 nm for the estimation of FFD. The linearity of the calibration curve considered the range of concentrations of 2.0–12.0 and 2.5–25.0 µg/mL for FFD and FP, respectively. The accuracy and precision of the three achieved methods have been assayed to verify their validation according to ICH guidelines. They were 100.1 ± 1.3, 101.5 ± 0.5, and 101.2 ± 1.2 for FP, and 99.2 ± 1.6 and 100 ± 2 related to FFD. Regarding precision, the relative standard deviation was not more than 1.5%. The specificity of the three methods was estimated through their determination in various synthetic laboratory mixes. Additionally, the obtained results by the suggested procedures are compared statistically to those obtained by the reported HPLC technique. Another statistical comparison was done using a one-way ANOVA test; all of them showed no discernible differences. The three methods are specific, simple, and do not require sophisticated instruments. They can be employed in quality control laboratories for routine assays of two drugs in pure raw powder, synthetic laboratory-prepared mixes, and medication dosage forms quantitatively, and have been successfully utilized and validated.

This paper proposes and validates an automatic control tuning methodology based on initial frequency response. This approach facilitates the design of robust PID controllers for overdamped systems characterized by S-shaped step responses. In the prior autotuner, which is inherently robust, the critical frequency value is determined via the relay test, while process frequency response and its derivative at this frequency are found using the sine test. Our novel approach offers a fully automated calculation for these parameters based solely on the step response test (i.e., minimal information from the process), eliminating the need for additional calculations by relay and sine tests. For this aim, it estimates these values employing the first order plus dead time models. Firstly, five step response methods are introduced to ascertain the model parameters. Secondly, three alternative estimation methods for the critical frequency of the system are proposed through (i) solving a nonlinear equation, (ii) employing a linear approximation, and (iii) using a power regression. Lastly, the model parameters are then employed to calculate the system frequency response and its derivative at the critical frequency. The remaining design steps are the same as in the initial robustness-based autotuner. In the simulation studies, two types of overdamped systems are considered. The critical frequency estimation values obtained from three estimation methods are compared to each other. Additionally, the impact of the step response methods and the proposed estimation methods within the novel approach on system response and control signal are investigated. The designed controllers use a new approach to the initial autotuner and are implemented on a two-tank liquid-level system. The experimental outcomes are in accordance with the simulation results, confirming the validity and compatibility of the findings. Quantitative performance metrics are used to evaluate the effectiveness of the designs comprehensively.

The plastic scintillation optical fiber (PSOF) detector, characterized by its large contact area with measurement targets, effectively detects and quantifies radiation in diverse radiation-contaminated areas and liquid environments. While it is extensively utilized for measuring alpha, beta, gamma, and neutron radiations, comprehensive documentation on the spectrum measurement and energy calibration methods for gamma nuclides has not been reported. Accurate energy calibration is crucial for the precise quantification of radiation doses from various sources. The pulse-height spectrum produced by the PSOF detector does not display a Compton maximum because of the significant Gaussian energy broadening. Additionally, this spectrum compresses as the distance increases between the radiation source and the light measurement device. In this study, the energy spectrum of a PSOF for gamma nuclides was characterized by energy calibrations using Compton edge (CE). The CE channel in the measurement spectrum of the PSOF detector for three gamma nuclides was identified using the first-order differentiation method. This technique was successfully applied to spectra measured at various radiation source positions to determine the attenuation coefficients. The proposed energy calibration method allows for the conversion of pulse-height spectra obtained from alpha, beta, and neutron radiation measured with PSOF detectors into energy spectra.

In this research, the application of the first order derivative spectra was employed to determine the levels of caffeine (CAF) and chlorogenic acids (CGA) in defective (immature, black, and sour) and nondefective coffee beans without using extraction or background correction techniques. The extreme points of first order derivate spectra of these compounds were at the wavelength of 260 and 292 nm enable to quantify the contents of CAF and CGA, respectively. The level of CAF and CGA in coffee beans determined by this method is ranged from 1.2 ± 0.12–1.46 ± 0.47% and 4.04 ± 0.44–4.43 ± 0.43%, respectively. The study results also indicated total contents of CAF and CGA levels discriminate the defective and nondefective coffee beans with higher CAF and CGA contents being observed in defective coffee beans. As the method is extremely rapid, easy, and inexpensive and also requires minimal sample preparation for the quantification of CAF and CGA contents in coffee, it could be a valuable quality control technique. First order derivative spectra to determine CGA and CAF in coffee beans.

Superpixel segmentation can benefit from the use of an appropriate method to measure edge strength. In this paper, we present such a method based on the first derivative of anisotropic Gaussian kernels. The kernels can capture the position, direction, prominence, and scale of the edge to be detected. We incorporate the anisotropic edge strength into the distance measure between neighboring superpixels, thereby improving the performance of an existing graph-based superpixel segmentation method. Experimental results validate the superiority of our method in generating superpixels over the competing methods. It is also illustrated that the proposed superpixel segmentation method can facilitate subsequent saliency detection.