Correlation Factor R2 Research Articles

Geographical specificity of metabolomic traits among Amomum villosum Lour. Fruits from different areas in China

Amomum villosum Lour. is a common functional food that promote intestinal health. Yangchun City is considered the best habitat for A. villosum among all producing areas in China. However, no studies have shown a difference between Yangchun and other producing areas in terms of the metabolic profiles of A. villosum fruits. The current study analyzed the metabolic profiles of A. villosum fruit samples cultivated in five representative producing areas, and explored the associations with environmental factors. A total of 969 metabolites were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the potential biomarker clusters re-composed with 5 metabolites (indole-5-carboxylic acid, glutaric acid, afzelechin, 3-hydroxyanthranilic acid, and adenosine 5-diphosphate) (AUCs = 0.813–1.0) were shown to distinguish samples from different areas. OPLS-DA was performed to identify region-specific metabolites in each producing area. For the geo-authentic area (Yangchun), the prominent metabolites were mainly related to anti-inflammatory effects. Moreover, 11 environmental factors were significantly associated with the metabolites in A. villosum fruits (p < 0.05), and latitude was the highest correlation factor (r2 = 0.351, p = 0.004). This work provides a practical strategy for detecting adulterations of the geo-authentic habitat of A. villosum, and offers a scientific basis for the assessment of habitat suitability and introduction of high-quality A. villosum.

Structural Heterogeneity and “Crystallinity” Indices of Natural Kaolinites

To overcome the existing uncertainty in the interpretation of “crystallinity” indices of kaolinites, HI [Hinckley, 1963], IK [Stoch, Sikora, 1966; Stoch, 1974], QF [Range, Weiss, 1969], AGFI [Aparicio, Galán, 1999; Aparicio et al., 2006], WIRI [Chmielová, Weiss, 2002], their values obtained for a representative collection of 30 kaolinite samples were compared with the results of modeling the corresponding X-ray diffraction patterns. It is shown that all the studied samples consist of a mixture of almost defect-free high ordered HOK and defective low-ordered LOK kaolinite phases, and that there are relationships between the HOK content and the values of the “crystallinity” indices, which are described by different regression equations. The relationship is most pronounced for HOK and the Hinckley index, HI, which is described by the quadratic equation HOK (%) = 12.236 HI2 + 25.464 HI ‒ 1.2622 with the correlation factor R2 = 0.993. The resulting equations can be used to find concentrations of HOK and LOK in natural kaolinites. Comparison of structural parameters of defective kaolinites obtained by modeling of their X-ray diffraction patterns with those of Expert System [Plançon, Zacharie 1990] showed that the latter sometimes predicts: 1) single-phase highly defective kaolinites, while their diffraction pattern modeling establishes a mixture of HOK and LOK phases; and 2) in two-phase samples, the content of the low-defect phase (ldp) is greater than 100%.

Novel cells integrated biosensor based on superoxide dismutase on electrospun fiber scaffolds for the electrochemical screening of cellular stress

A novel electrochemical biosensor was developed to monitor fibroblast cells stress levels for the first time in situ under external stimuli based on the recognition of superoxide anion released upon cell damage. The biosensor comprised metallized polycaprolactone electrospun fibers covered with zinc oxide for improved cell adhesion and signal transduction, whilst stable bioconjugates of mercaptobenzoic acid-functionalized gold nanoparticles/superoxide dismutase were employed as recognition bioelements. Biosensors were first tested and optimized for in situ generated superoxide detection by fixed potential amperometry at +0.3 V, with minimal interferences from electroactive species in cell culture media. L929 fibroblast cells were then implanted on the optimized biosensor surface and the biosensor morphologically characterized by scanning electron microscopy (SEM) and fluorescence microscopy, which illustrated the network-type pattern of fibroblasts adjacent to the fiber scaffold. Fibroblast stress was induced by zymosan and monitored at the cells integrated biosensor using fixed potential amperometry (CA) with a sensitivity of 26 nA cm-2 μg mL-1 zymosan and electrochemical impedance spectroscopy (EIS), with similar sensitivity of the biosensor considering the Rs and Z’ parameters of around 0.13 Ω cm2 μg-1 mL and high correlation factors R2 of 0.9994. The obtained results underline the applicability of the here developed biosensor for the electrochemical screening of the fibroblast cells stress. The concept in using low-cost biocompatible polymeric fibers as versatile scaffolds for both enzyme immobilization and cell adhesion, opens a new path in developing biosensors for the in-situ investigation of a variety of cellular events.

Estimation of Nine Organic Volatile Impurities in Bulk Dapagliflozin propandiol hydrate and Dosage forms from different sources using a new developed HS-GC-FID method

As a part of impurity profiling, we aimed in this work to determine the content of organic volatile impurities (OVIs), commonly known as residual solvents (RSs), in different sources of dapagliflozin propandiol monohydrate as raw materials and marketed film-coated tablets. For that, a novel HS-GC-FID method has been developed and validated for determination of methanol, ethanol, ether, acetonitrile, dichloromethane, n-hexane, ethyl acetate, tetrahydrofuran and toluene. Dimethyl sulfoxide DMSO was used us diluent. The separation was achieved on Agilent DB-624 (30m, 0.530mm, 3.0µm) column and nitrogen as carrier gas with a total run time of 20 minutes. Solvents peaks indicate high resolution. Correlation factor R2 was estimated for each solvent and values ranged from 0.9990 to 0.9995. Estimation of limit of detection of these nine solvents showed that developed method was more sensitive than published method. The percentage recoveries calculated and the values ranged from 100.2% to 111.54%. The methods has been found to be simple, very sensitive, rugged, reliable and reproducible for the quantitation of these solvents in different sample of dapagliflozin raw materials and marketed tablets. Ethanol (class 3) and n-hexane (class 2) were detected in unacceptable level in some marketed samples.

Validation of a rail temperature model with experimental measurements

Rail temperature is a key factor when studying the effects of thermal buckling. Many models have been developed to simulate rail temperatures under various weather conditions. This work is based on the model developed by the Chungnam National University (CNU), which includes the shadow effect on the rail and the solar position to improve the temperature prediction during several periods of the day, validates it with experimental data, and compares it with a finite element model. Furthermore, a python library is developed based on the lumped thermal model with small adaptations, called railtemp. The python package has slightly better performance over the original CNU model, reaching a correlation factor R2 of 0.947 and a root mean square error of 2.6°C. Furthermore, a new proposal is presented to determine the temperatures on rail tracks based on air temperature.

Comparison of sorption efficiency of natural and MnO2 coated zeolite for copper removal from model solutions

Removal of heavy metals from the environment is important for living beings. The present work investigates the applicability of the natural and MnO2 - coated zeolite as sorbent for the removal of copper from synthetic solutions. Batch experiments were carried out to identify the influence of initial pH and concentration in the process of adsorption. A maximum removal efficiency of Cu(II) was observed in 10 mg/L for natural (95.6%) and modified (96.4%) zeolite, where the values was almost identical, but at concentration of 500 mg/L was the removal efficiency of modified zeolite three times higher. Based on the correlation factors R2, the Langmuir isotherms better describe the decontamination process than Freundlich. The optimum pH value was set at 5.0.

Water Phase Inclination Theory for Hydraulic Conductivity Determination of Vadose Zones in Shallow Water Table Systems

Water Phase Inclination is an innovative theory for hydraulic conductivity and determination of vadose zone overlying shallow water table systems. It was originated and analytically derived from Darcy's Law and based on some physio-mechanical properties of soil. Al-Musayab area of 176 Km2 at Mesopotamian region, mid-Iraq was undertaken as a case study. It consists of unconsolidated quaternary deposits and is usually finer-grained than the underlying pebbly sandstone with Mediterranean weather. The Experimental part was divided into field tests which include double ring infiltrometer tests, water table depth measurements and sampling of 32 undisturbed soil samples of surface layers scattered over the study area Whereas lab tests include; the falling and constant head permeability, grain size distribution (sieve and hydrometer analysis), soil specific gravity, direct shear tests and the measuring of Water Phase Inclinations. Angle \emptyset a glassy infiltration box is an experimental device that was manufactured to measure the Water Phase Inclination angle and aquifer simulation. It is found a generalized linear relationship between  and the angle of internal friction which is valid for   23.37 with correlation factor R² = 0.99 and both angles depend on soil texture. The k values estimated by WPI theory and that measured by traditional techniques offer a linear relationship with acceptable Root Mean Square Error equals 0.0642 &lt; 0.1 the max allowable limit and correlation factor R² = 0.96, pointing out to the reliability and stability of the Water Phase Inclination results.

Reverse engineering for estimation of shear modulus for yarn models in finite element modelling for ballistic impact

In finite element (FE) modelling of ballistic performance of fabric, shear moduli of continuous yarn models are usually specified based on approximations and assumptions, despite their significant influence on energy absorption and yarn failure time in a ballistic impact event. This paper applies reverse engineering method for estimating shear modulus G13 of a continuous multifilament yarn model for simulating the ballistic behaviour of the yarn or its fabric. A ballistic event of Dyneema® SK65 yarn model impacted by a projectile travelling at 477 m/s is used to illustrate the establishment of the methodology. The procedure starts by relating G13 and transverse wave velocity (ut) through regression whose correlation factor R2 is 0.999. ut is calculated by the classical Smith equations. The regressed relation and the availability of ut value enable the calculation of G13. The simulated results of the Dyneema® yarn model with such estimated G13 show healthy agreements to the analytical and experimental counterparts in terms of ut and the slope angle of fabric deflection θ. The reverse engineering method has been used for obtaining G13 successfully for yarn models of other materials, e.g. Kevlar KM2 and Zylon®, in simulating their transverse deflection behaviour under the ballistic impact.

A PSO-ANN Intelligent Hybrid Model to Predict the Compressive Strength of Limestone Fillers Roller Compacted Concrete (RCC) to Build Dams

The compressive strength of the roller-compacted concrete (RCC) is an essential indicator of quality when designing dams. RCC is optimized in most cases through experimental studies conducted vigorously. This study aims at developing a smart system to predict the compressive strength of the limestone fillers RCC that is used to build dams. The prediction is made base on the following parameters: the maximum diameter of the aggregates, the compactness of the granular mixture, the rates of both cement and limestone fillers, water/cement ratio and the RCC age. The cement strength is taken in to consideration using a corrective equation. Two metaheuristic systems are developed: artificial neural networks (ANN), and a hybrid system consisting of an ANN optimized by a particle swarm optimization (PSO) algorithm. An experimental database is built containing 500 vectors taken from RCC formulations given by lab activity reports about 04 dam projects. The best results were achieved through the PSO-ANN hybrid system. This prediction system is validated by an experimental study conducted on 20 RCC formulations, and a comparison was made with the Laboratoire Central des Ponts et Chaussees (LCPC) method. The prediction resulting from the PSO-ANN system is of a good accuracy level with a correlation factor R2 = 0.85 and a low root mean squared error of 1.45. Finally, a user interface based on the model developed is created.

Hemostatic wound dressings based on drug loaded electrospun PLLA nanofibrous mats

Novel wound dressings were prepared using electrospun nanofibrous PLLA mats loaded with aluminum chloride (AlCl3), gentamicin sulphate (GS) and/or lidocaine hydrochloride (LHc) as a hemostatic, antibiotic, and local anesthetic drug, respectively. Structural characterization of the prepared mats was performed using FTIR spectroscopy, whereas morphological characteristics were determined using SEM micrographs of the fibers. For mats loaded with AlCl3, the majority of the fibers diameters were in the range [400–500 nm]. The wettability of the mats was investigated using contact angles method. Hemostasis tests have shown that all the prepared mats have better hemostatic efficiency than gauze bandage. However, mats loaded with only AlCl3 30%w/w have the best hemostatic performance with a decrease in blood clotting time of 80% and an increase in blood absorption capacity of 178% in comparison with gauze bandage. GS release kinetics in PBS solution was investigated. The experimental results showed that the release kinetics follows Korsmeyer-Peppas model with a correlation factor R2 = 0.999 and n = 0.1.

Tuning of hydrogen peroxide etching during the synthesis of silver nanoparticles. An application of triangular nanoplates as plasmon sensors for Hg2+ in aqueous solution

Abstract A simple method to prepare silver nanoparticles (AgNPs) with different shapes and dimensions was optimized by using a one-step reduction method with NaBH4, TSC and PVP, with H2O2 acting as an oxidation agent, to etch the nanoparticles and produce different morphologies. A series of AgNPs were obtained with different colours, including yellow to green and passing through orange, red, violet and blue, that exhibited different localized surface plasmon resonance (LSPR) as analysed by UV–visible spectroscopy. The dimensions and morphologies of the nanostructures were characterized in detail by scanning electron microscopy (SEM) and dynamic light scattering (DLS) techniques. The characterizations showed different trends in the morphologies, starting from spherical to not well-defined structures, triangular nanoplates, hexagonal nanoplates and ultimately once again showing quasi-spherical shapes. The triangular nanoplates were tested as plasmon sensors for mercury ions in aqueous solution, and they showed an LSPR-blueshift with a change in colour from blue to violet. When a calibration curve was measured in the concentration range from 0.14 to 0.5 mg l−1, the nanoparticles showed good linearity between the Hg2+ concentration in the solutions and the LSPR blueshift, with a correlation factor R2 of 0.9978 and an LOD of 0.013 mg l−1 (64.9 nM).

Thermochemical study for remediation of highly concentrated acid spill: Computational modeling and experimental validation

The release of concentrated acid solutions by chemical accidents is disastrous to our environmental integrity. Alkaline agents applied to remedy the acid spill catastrophe may lead to secondary damages such as vaporization or spread out of the fumes unless substantial amount of neutralization heat is properly controlled. Using a rigorous thermodynamic formalism proposed by Pitzer to account short-range ion interactions and various subsidiary reactions, we develop a systematic computational model enabling quantitative prediction of reaction heat and the temperature change over neutralization of strongly concentrated acid solutions. We apply this model to four acid solutions (HCl, HNO3, H2SO4, and HF) of each 3 M-equivalent concentration with two neutralizing agents of calcium hydroxide (Ca(OH)2) and sodium bicarbonate (NaHCO3). Predicted reaction heat and temperature are remarkably consistent with the outcomes measured by our own experiments, showing a linear correlation factor R2 greater than 0.98. We apply the model to extremely concentrated acid solutions as high as 50 wt% where an experimental approach is practically restricted. In contrast to the extremely exothermic Ca(OH)2 agent, NaHCO3 even lowers solution temperatures after neutralization reactions. Our model enables us to identify a promising neutralizer NaHCO3 for effectively controlling concentrated acid spills and may be useful for establishment of proper strategy for other chemical accidents.

Batch Adsorption of Synthetic Dye by Maclura Pomifera, a New Eco-Friendly Waste Biomass: Experimental Studies and Modeling

Abstract The removal of Methylene blue (MB) from aqueous medium using alkaline modified Maclura pomifera (NaOH-MMP) has been studied in this work. Results showed that a pH value of 6 was favorable for the adsorption of MB. Rate constants of pseudo-first-order, pseudo-second-order and nth kinetic model were determined to analyze the dynamic of the adsorption process; they showed that adsorption kinetics followed a pseudo-second-order and nth kinetic models. The Sips isotherm model was found to be the most relevant to describe MB sorption onto NaOH-MMP with a correlation factor R2 &gt; 0.999. The adsorption capacity of NaOH-MMP was found to be 160 mg g−1 at 25 °C, confirming its biosorbent efficiency for the removal of MB dye from aqueous solutions. Thermodynamic parameters indicated that the MB adsorption onto adsorbent was feasible in nature, spontaneous, and exothermique.

Influence of linearity in Weibull plot on accuracy of parameter estimation

Abstract This paper deals with influence of linearity in Weibull plot on accuracy of parameter estimation. Random numbers were generated as fracture probability, and transformed into virtual strength data at given Weibull parameters (m = 20, β= 100 MPa). The data was analyzed by Weibull plot method to estimate its Weibull parameters (m*, β*). This type of numerical simulation was repeated 1000 times at the number of specimens between 5 and 100. Comparison between the estimated Weibull parameters (m*, β*) and the given Weibull parameters (m = 20, β= 100 MPa) shows us that parameter estimation by Weibull plot method has sufficient accuracy when the square of correlation factor R2 ≥ 0.90 in Weibull plot.

The Determination of Dendrite Coherency Point Characteristics Using Three New Methods for Aluminum Alloys

The aim of this work is to give an overview of existing methods and to introduce three new methods for the determination of the Dendrite Coherency Point (DCP) for AlSi10Mg alloys, as well as to compare the acquired values of DCP based on a thermal analysis and on the analysis of cooling curves working with only one thermocouple. Additionally, the impact of alloying and contaminant elements on the DCP will be also studied. The first two proposed methods employ the higher order derivatives of the cooling curves. The DCP was determined as the crossing point of the second and third derivative curves plotted versus time (method 1) or that of the temperature (method 2) with the zero line just after the maximum liquidus temperature. The third proposed method is based on the determination of the crossing point of the third solid fraction derivative curve with the zero line, corresponding to a minimum of the second derivative. A Taguchi design for the experiments was developed to study the DCP values in the AlSi10Mg alloy. The DCP temperature values of the test alloys were compared with the DCP temperatures predicted by the previous methods and the influence of the major and minor alloying elements and contaminants over the DCP. The new processes obtained a correlation factor r2 from 0.954 and 0.979 and a standard deviation from 1.84 to 2.6 °C. The obtained correlation values are higher or similar than those obtained using previous methods with an easier way to define the DCP, allowing for a better automation of the accuracy of DCP determination. The use of derivative curves plotted versus temperature employed in the last two proposed methods, where the test samples did not have an influence over the registration curves, is proposed to have a better accuracy than those of the previously described methods.

Colorimetric detection of amoxicillin based on querecetagetin coated silver nanoparticles

A different approach to the molecular recognition events consists in synthesis and conjugating silver nanoparticles with flavonoid quercetagetin isolated from T. erecta. In this article we are reporting rapid and feasible procedure for the synthesis of querecetagetin stabilized silver nanoparticle (Qt AgNPs). These nanoparticles were characterized by UV–vis spectroscopy, FTIR, and AFM techniques. The average size of the querecetagetin coated silver nanoparticles was found to be in the range from 25 to 45 nm and are highly robust. Querecetagetin coated silver nanoparticle selectively recognize amoxicillin producing a bathochromic shift along with color change from yellow to reddish. The detection limit was calculated using standard deviation of blank and slope of regression line and was found to be 4.46 μM with a correlation factor R2 equal to 0.993. The binding stoichiometry between Qt AgNPs and amoxicillin was found to be 1:2 (Qt AgNPs: amoxicillin) as revealed by Job‘s plot. The Qt AgNPs interact selectively with amoxicillin in human blood plasma and tap water sample showing that the ingredients of tap water and blood plasma are inert towards the interaction of Qt AgNPs with amoxicillin.Photophysical events were examined using UV–vis, FTIR spectroscopy and, AFM techniques.

High efficiency of methylene blue removal using a novel low-cost acid treated forest wastes, Cupressus semperirens cones: Experimental results and modeling

ABSTRACTThe removal of methylene blue (MB) from aqueous solutions using sulfuric acid modified Cupressus semperirens cones (H2SO4-CSC), was investigated. Results showed that a pH value of 12 was favorable for the adsorption of MB and that the moisture and ash yields are suitable for industrial exploitation. A high porosity value was found, 68.1%. In agreement with its low content of basicity compared to its acidity, the H2SO4-CSC absorbent had an acidic behavior. Rate constants of pseudo-first-order, pseudo-second-order, and nth kinetic model were determined to analyze the dynamic of the biosorption process; they showed that adsorption kinetics followed a pseudo-second-order and nth kinetic models. Ionic strength was shown to have a negative impact on the biosorption of MB onto H2SO4-CSC. The Sips isotherm model was found to be the most relevant to describe MB biosorption onto H2SO4-CSC with a correlation factor R2 > 0.999. The biosorption capacity of H2SO4-CSC was found to be 460 mg g−1 at 10°C and 590 mg g−1 at 25°C, confirming biosorbent efficiency for the removal of MB dye from aqueous solutions. Thermodynamic parameters indicated that the biosorption process of MB was endothermic and more effective at high temperatures. The values of ΔG° and ΔH° confirmed that the biosorption of MB onto H2SO4-CSC was spontaneous and endothermic in nature. An irregular increase in randomness at the H2SO4-CSC–solution interface during the biosorption process was suggested by the positive values of ΔS°.

The comminution energy-size reduction of the Bond Mill and its relation to Vickers Hardness

The results of Bond Work index (BWi) tests of five materials with five closing screen size (P1) of 63o 500 µm are documented. These are normalized to eliminate the effect of material present finer than the closing screen sizes and test sample apparent densities. Analysis of normalized test results show, with a correlation factor R2 of 0.9956, that the revolutions required in all the Bond Work index mill tests conducted (29–419 revolutions) corresponds to a specific grinding energy per Bond Mill revolution of 0.0823 kWh/ton for a material corrected to a tapped apparent density of 1 t/m3 and for material present finer than the closing screen size. Conversion of this value to operation of the mill for the Bond Work index test results in a value of 194 ∗ 10−7 kWh/mill revolution.It is demonstrated that the indicated specific grinding energy of the Bond Mill revolution is not a precise value. An exponential function with a perfect correlation is presented relating the final required number of Bond Work index test mill revolutions required with the P1 values for sample materials tested.A perfect correlation with an exponential relation to the evolution of the specific grinding energy with change in closing screen size is presented. This relation is interpreted as a measure of the reduction in grinding efficiency with increase in fineness of grinding.It also shown that there is an exponential relation with a R2 correlation factor of 0.9900 between experimental specific grinding energy of a mono-mineralogical material normalized for <P1 content and apparent density to the root of its VH at a given P1. Most if not all the deviations between the calculated specific grinding energy based on P1 values and the sample Vickers Hardness correlates with the differences between the experimental and corrected mill revolutions applied to compensate for the <P1 fines contents of the test samples.

Removal of tiemonium methylsulfate, from aqueous solutions using activated carbon prepared from date stones

ABSTRACTThe retention of a pharmaceutical compound, tiemonium methylsulfate (TIM), from aqueous solutions by adsorption onto activated carbon prepared from date stones (AC–DS) was investigated. Physical and chemical characteristics of this material were also determined. Results showed that pH 8 was optimal for TIM adsorption. Among the kinetic models considered, the pseudo-second-order model was the most appropriate to describe experimental data. Regarding adsorption isotherms, it was shown that the Sips model accurately describe the sorption of TIM onto AC–DS with a correlation factor R2 > 0.98. The adsorption capacity of AC–DS was found to be 42.2 mg g−1 at 10°C and 60.5 mg g−1 at 25°C, confirming its efficiency for the removal of this compound from aqueous solutions. The values of ΔG0 and ΔH0 confirmed that the adsorption of TIM onto AC–DS was spontaneous and endothermic in nature and hence more effective at high temperatures. An irregular increase in the randomness was suggested at the AC–DS solution interface during the adsorption process for positive values of ΔS0.

CO2 Gasification of Sugar Cane Bagasse: Quantitative Understanding of Kinetics and Catalytic Roles of Inherent Metallic Species

A total of 18 chars from the pyrolysis of six trios of sugar cane bagasses (SCBs; original, water-washed, and acid-washed) were gasified with CO2 at 900 °C, aiming at a quantitative description of the rate of gasification catalyzed by inherent metallic species and a correlation of the catalytic activity and its change during the gasification with the metallic species composition. The measured kinetics was described quantitatively over a range of char conversion, 0–0.999, by a model that assumed progress in parallel of the catalytic gasification and non-catalytic gasification, together with the presence of a catalytic precursor and three to four types of catalysts having different activities and deactivation characteristics. A series of regression analyses was scrutinized and reached expression of initial catalytic activity as a linear function of Na, K, Ca, Fe, and Si concentrations in the char with a correlation factor (r2) of >0.98. The catalyst precursor contributed fully by water-soluble Na, K, and Ca...