Combined Surfactant and Enzyme-Assisted Extraction of Pectin from Hawthorn (Crataegus monogyna Jacq.) Fruits

Introduction. Commercial pectin is usually obtained from apples or citrus fruits. However, some wild fruits, such as hawthorn, are also rich in pectin with valuable nutritional and medical properties. The research objective was to study and improve the process of combined surfactant and enzyme-assisted extraction of pectin from hawthorn fruits. Study objects and methods. The study involved a 1% solution of Polysorbate-20 surfactant and a mix of two enzymes, namely cellulase and xylanase, in a ratio of 4:1. The response surface methodology with the Box-Behnken experimental design improved the extraction parameters. The experiment featured three independent variables – temperature, time, and solvent-to-material ratio. They varied at three levels: 20, 40, and 60°C; 120, 180, and 240 min; 15, 30, and 45 mL per g. Their effect on the parameters on the pectin yield was assessed using a quadratic mathematical model based on a second order polynomial equation. Results and discussion. The response surface methodology made it possible to derive a second order polynomial regression equation that illustrated the effect of extraction parameters on the yield of polyphenols. The regression coefficient (R2 = 98.14%) and the lack-of-fit test (P > 0.05) showed a good accuracy of the model. The optimal extraction conditions were found as follows: temperature = 41°C, time = 160 min, solvent-to-material ratio = 32 mL per 1 g. Under the optimal conditions, the predicted pectin yield was 14.9%, while the experimental yield was 15.2 ± 0.4%. The content of galacturonic acid in the obtained pectin was 58.5%, while the degree of esterification was 51.5%. The hawthorn pectin demonstrated a good complex-building ability in relation to ions of copper (564 mg Cu2+/g), lead (254 mg Pb2+/g), and cobalt (120 mg Co2+/g). Conclusion. Combined surfactant and enzyme-assisted extraction made improved the extraction of pectin from hawthorn fruits. The hawthorn pectin can be used to develop new functional products.

Evaluation of Calibration Equations by Using Regression Analysis: An Example of Chemical Analysis

A calibration curve is used to express the relationship between the response of the measuring technique and the standard concentration of the target analyst. The calibration equation verifies the response of a chemical instrument to the known properties of materials and is established using regression analysis. An adequate calibration equation ensures the performance of these instruments. Most studies use linear and polynomial equations. This study uses data sets from previous studies. Four types of calibration equations are proposed: linear, higher-order polynomial, exponential rise to maximum and power equations. A constant variance test was performed to assess the suitability of calibration equations for this dataset. Suspected outliers in the data sets are verified. The standard error of the estimate errors, s, was used as criteria to determine the fitting performance. The Prediction Sum of Squares (PRESS) statistic is used to compare the prediction ability. Residual plots are used as quantitative criteria. Suspected outliers in the data sets are checked. The results of this study show that linear and higher order polynomial equations do not allow accurate calibration equations for many data sets. Nonlinear equations are suited to most of the data sets. Different forms of calibration equations are proposed. The logarithmic transformation of the response is used to stabilize non-constant variance in the response data. When outliers are removed, this calibration equation’s fit and prediction ability is significantly increased. The adequate calibration equations with the data sets obtained with the same equipment and laboratory indicated that the adequate calibration equations differed. No universe calibration equation could be found for these data sets. The method for this study can be used for other chemical instruments to establish an adequate calibration equation and ensure the best performance.

Optimization of Anthocyanin Extraction from Cockspur Coral (Erythrina Crista-Galli L.) Petals with Microwave-Assisted Extraction (MAE) using Response Surface Methodology

Cockspur coral (Erythrina crista-galli L) petals are flowers that contain anthocyanins and active compounds of flavonoids and tannins. This study aims to determine the optimum conditions for the anthocyanin extraction process of cockspur coral petals using Microwave-Assisted Extraction (MAE), analyzed through the Response Surface Method (RSM). This process uses ethanol-hydrochloric acid solvents and a Box-Behnken experimental design involving three factors, namely the solvent ratios (w/v) (1:5, 1:15, and 1:25), microwave powers (300, 450, and 600 watts), and extraction times (3, 9, and 15 minutes). As a result, the second-order polynomial model was enhanced and sufficient to explain the variation of the data that denoted the significant correlation with the independent variables and the response. Derringer's desired function methodology was used for optimizing studies and generated ideal conditions for each or combined an independent variable. The optimum anthocyanin extract of 5.82 mg/L was obtained at a power condition of 325,5 Watts, an extraction time of 3.05 minutes, and a solvent ratio of 20.5. Meanwhile, the operating conditions at a power of 310.8 Watts, a time of 14.94 minutes, and a solvent ratio of 24.96 resulted in the optimum color intensity (IC) of 1040.26. In the meantime, the optimum antioxidant activity was obtained at a power of 585.97 Watts, a time of 4.93 minutes, and a solvent ratio of 5.43 with IC50 of 0.115.

Dissolution of Silk Fibroin in Mixtures of Ionic Liquids and Dimethyl Sulfoxide: On the Relative Importance of Temperature and Binary Solvent Composition

We studied the dependence of dissolution of silk fibroin (SF) in mixtures of DMSO with ionic liquids (ILs) on the temperature (T = 40 to 80 °C) and DMSO mole fraction (χDMSO = 0.5 to 0.9). The ILs included BuMeImAcO, C3OMeImAcO, AlBzMe2NAcO, and Bu4NAcO; see the names and structures below. We used design of experiments (DOE) to determine the dependence of mass fraction of dissolved SF (SF-m%) on T and χDMSO. We successfully employed a second-order polynomial to fit the biopolymer dissolution data. The resulting regression coefficients showed that the dissolution of SF in BuMeImAcO-DMSO and C3OMeImAcO-DMSO is more sensitive to variation of T than of χDMSO; the inverse is observed for the quaternary ammonium ILs. Using BuMeImAcO, AlBzMe2NAcO, and molecular dynamics simulations, we attribute the difference in IL efficiency to stronger SF-IL hydrogen bonding with the former IL, which is coupled with the difference in the molecular volumes and the rigidity of the phenyl ring of the latter IL. The order of SF dissolution is BuMeImAcO-DMSO > C3OMeImAcO-DMSO; this was attributed to the formation of intramolecular H-bonding between the ether oxygen in the side chain of the latter IL and the relatively acidic hydrogens of the imidazolium cation. Using DOE, we were able to predict values of SF-m%; this is satisfactory and important because it results in economy of labor, time, and material.

A Discussion on Sea Level Rise, Rate Ad Acceleration. Venice as a Case Study

The paper discusses the equations used to represent the sea level rise, and in particular the second-order polynomial, generally preferred because its second-order coefficient is related to acceleration. The long series of the sea level rise in Venice offers a particularly useful case study from 1350 to 2016, because it may be equally represented, at the same level of explained variance, by an exponential or a quadratic best-fit equation. The first-order and the second-order derivatives respectively represent the rate and the acceleration of sea level rise. The derivatives obtained from the second-order polynomial representation generate a linear rate and a constant acceleration, while those derived from an exponential preserve the exponential character. The two rates (i.e. from the quadratic and the exponential equations), and the two accelerations are characterized by different equations and different plots, but their average values are the same. The second-order polynomial with constant acceleration is in line with a climate with constant forcing factors; the exponential with a dynamic condition with increasing forcing factors and acceleration. Mathematical formulae and physical consequences are discussed in the framework of different scenarios. Finally, the trend-forecast extrapolation is discussed and applied to the case study of Venice. It is shown that, in the most optimistic assumption of forcing increasing at unchanged rate, the sea level in Venice will rise by 33.8 ± 4 cm over this century, that may be compared to the 31 cm of the similar, most optimistic prediction made by IPCC for business-as-usual.

Convergence of undulatory swimming kinematics across a diversity of fishes

Fishes exhibit an astounding diversity of locomotor behaviors from classic swimming with their body and fins to jumping, flying, walking, and burrowing. Fishes that use their body and caudal fin (BCF) during undulatory swimming have been traditionally divided into modes based on the length of the propulsive body wave and the ratio of head:tail oscillation amplitude: anguilliform, subcarangiform, carangiform, and thunniform. This classification was first proposed based on key morphological traits, such as body stiffness and elongation, to group fishes based on their expected swimming mechanics. Here, we present a comparative study of 44 diverse species quantifying the kinematics and morphology of BCF-swimming fishes. Our results reveal that most species we studied share similar oscillation amplitude during steady locomotion that can be modeled using a second-degree order polynomial. The length of the propulsive body wave was shorter for species classified as anguilliform and longer for those classified as thunniform, although substantial variability existed both within and among species. Moreover, there was no decrease in head:tail amplitude from the anguilliform to thunniform mode of locomotion as we expected from the traditional classification. While the expected swimming modes correlated with morphological traits, they did not accurately represent the kinematics of BCF locomotion. These results indicate that even fish species differing as substantially in morphology as tuna and eel exhibit statistically similar two-dimensional midline kinematics and point toward unifying locomotor hydrodynamic mechanisms that can serve as the basis for understanding aquatic locomotion and controlling biomimetic aquatic robots.

Optimization of rosmarinic acid extraction from lemon balm (Melissa officinalis)

The aim of this study was optimization of rosmarinic acid extraction from lemon balm (Melissa officinalis). The optimal conditions for the extraction of rosmarinic acid from lemon balm were determined using response surface methodology (RSM). A center composide design (CCD) was used to investigate the effects of three independent variables, namely solid-liquid radio, solvent composition (%) and extraction temperature (°C). Dependent variable was yield of rosmarinic acid. A second-order polynomial model was used for predicting the response. Optimized conditions for rosmarinic acid were: PEME 1:29 (w/v), temperature 66 °C a % propan-2-ol 34 %. The experimental values agreed with predicted within a 95 % confidence interval. Yield of rosmarinic acid extraction by these optimized conditions was achieved 72.6 mg of rosmarinic acid / g of dry extraction matter.

Kirchhoff-Love Plate Theory: First-Order Analysis, Second-Order Analysis, Plate Buckling Analysis, and Vibration Analysis Using the Finite Difference Method

This paper presents an approach to the Kirchhoff-Love plate theory (KLPT) using the finite difference method (FDM). The KLPT covers the case of small deflections, and shear deformations are not considered. The FDM is an approximate method for solving problems described with differential equations. The FDM does not involve solving differential equations; equations are formulated with values at selected points of the structure. Generally in the case of KLPT, the finite difference approximations are derived based on the fourth-order polynomial hypothesis (FOPH) and second-order polynomial hypothesis (SOPH) for the deflection surface. The FOPH is made for the fourth and third derivative of the deflection surface while the SOPH is made for its second and first derivative; this leads to a 13-point stencil for the governing equation. In addition, the boundary conditions and not the governing equations are applied at the plate edges. In this paper, the FOPH was made for all of the derivatives of the deflection surface; this led to a 25-point stencil for the governing equation. Furthermore, additional nodes were introduced at plate edges and at positions of discontinuity (continuous supports/hinges, incorporated beams, stiffeners, brutal change of stiffness, etc.), the number of additional nodes corresponding to the number of boundary conditions at the node of interest. The introduction of additional nodes allowed us to apply the governing equations at the plate edges and to satisfy the boundary and continuity conditions. First-order analysis, second-order analysis, buckling analysis, and vibration analysis of plates were conducted with this model. Moreover, plates of varying thickness and plates with stiffeners were analyzed. Finally, a direct time integration method (DTIM) was presented. The FDM-based DTIM enabled the analysis of forced vibration of structures, with damping taken into account. In first-order, second-order, buckling, and vibration analyses of rectangular plates, the results obtained in this paper were in good agreement with those of well-established methods, and the accuracy was increased through a grid refinement.

Effects of the adjacent channels on IP3 and IP5 of RF amplifier

This paper discusses the impact of the adjacent channels on the 1-dB compression point, the IP3 and the IP5 of Radio Frequency (RF) amplifier by n-tone test. By combining the theoretical derivation and software simulation, the model analysis for the third/five order polynomial nonlinear amplifier has been achieved. Moreover, the control variable method is adopted to draw the curves for the input/output signals. The research shows that the 1-dB compression point, the IP3 and the IP5 drop as n increases, and they all have symmetry for a given n. The fifth-order polynomial nonlinear amplifier model is proposed, the research shows that the adjacent channels have a great impact on the 1-dB compression point, the IP3 and the IP5 of the desired channel. This effect must be taken into account in actual RF amplifier designs and wireless communication architectures.

A Semi-Analytical Model for Gravitational Microlensing

<p>This thesis describes the theory and implementation of a semi-analytical model for gravitational microlensing. Gravitational microlensing is observed when a distant background `source' star comes into close alignment with an intermediate `lens' star. The gravitational eld of the lens de ects the paths of light emitted from the source, which causes an increase in its observed brightness. As the alignment of the two stars changes with time, the apparent magni cation of the source follows a well de ned `lightcurve'. A companion body (such as a planet) orbiting the lens star can introduce large deviations from the standard lightcurve, which can be modelled to determine a mass ratio and separation for the companion(s). This provides a means to detect extrasolar planets orbiting the lens star. We show, from basic principles, the development of the standard model of a mi- crolensing event, including the e ect of multiple lens masses and orbital motion. We discuss the two, distinctly di erent, numerical approaches that are used to calculate theoretical lightcurves using this model. The `ray shooting' approaches are discussed with reference to the previously developed modelling code (MLENS), which implemented them. This is followed by a comprehensive description of the `semi-analytical' approaches used in the new software (mlens2) developed during this thesis programme; a key feature of these techniques is the determination of the source magni cation from the roots of a high order polynomial. We also discuss the process of nding the best- t model for an observed microlensing event, with respect to the mlens2 software package. Finally, we demonstrate the capabilities of our semi-analytical model by generating theoretical lightcurves for the microlensing events OGLE-2005-BLG-390 and OGLE-2006-BLG-109 and comparing them to the observational data and published models.</p>