11351 research outputs found
Sort by
Impact of interfacial barriers onthe oxidative stability of lipophilicbioactive compounds in oil-in-wateremulsions - The case of lutein
No full textOils, which consist of fatty acids (FA), are dispersed in the aqueous phase of food emulsions. Under food processing conditions (e.g., high heat, shear forces), and in the presence of oxygen, polyunsaturated fatty acids (PUFA) may become oxidized. It is generally accepted that the interfacial region, which is the contact region between the oil phase and the aqueous phase, represents a critical area in the emulsion system with regard to the development of oxidation. A better understanding of the relationship between the interfacial region (oil droplet size) and interfacial composition (emulsifier type) may allow the creation of stable food emulsions against oxidation. Emulsifiers work by stabilizing oils suspended in water, and this is achieved electrostatically. A part of an emulsifier is attracted to water while its other part is attracted to the oil. The effects of emulsifiers in limiting the transport of free radicals across the emulsion interface and its impact on the oxidative stability of lipophilic bioactive compounds is an area of active research. The transport of free radicals across the emulsion interface can be measured using a peroxide method. The free radicals are generated in the aqueous phase using 2,2\u27-azobis (2-amidinopropane) dihydrochloride (AAPH). The peroxide method can reveal the barrier properties of emulsifiers towards a water-soluble radical initiator (AAPH) in emulsion systems. Lutein, a xanthophyll carotenoid, was selected as a lipophilic bioactive compound (phytonutrient) model to evaluate the interfacial barrier properties of emulsifiers in an emulsion-based delivery system prepared with corn oil, which is high in PUFA. The lutein-loaded emulsions were formulated with the following emulsifiers: bovine casein; caprine casein (αs1-I); and caprine casein (as1-II). The peroxide value (PV) demonstrated that lutein-loaded emulsions stabilized with caprine casein (αs1-II) provided a significantly (p \u3c 0.05) enhanced interfacial barrier limiting the transport of peroxyl radicals across the oil-water interface. In agreement with PV measurements, chemical (color) stability results showed that lutein was most stable (p\u3c0.05) under the photo-oxidative conditions when emulsions were stabilized by caprine casein (αs1-II). The better interfacial barrier properties exhibited by caprine casein (αs1-II) can be used to create lutein-loaded emulsion formulations with improved chemical (color) stability for food and beverage applications.
Treatment and Non-Treatment Professionals in Texas: Race, Sex, Age, and Level of Education Influencing Attitudes About Addiction
No full textUsing a two-step process, attitudes about addiction among Texas professionals working primarily with youth were examined. In Step 1, researchers examined attitudes about addiction in Texas (n = 1,078), across professionals working with youth. In Step 2, researchers selected a subset of treatment and non-treatment professionals (n = 522) and tested two hypotheses related to differences in attitudes between the two professional groups. Two research questions were also explored. Step 1 analyses revealed stronger endorsement of attitudes related to the psychological and sociological models, and that demographic variables were modest but significant predictors of attitudes about addiction. Step 2 analyses revealed that professional status and demographic variables were significant predictors of attitudes about addiction. Findings have implications for treatment seeking, treatment and non-treatment professional behavior toward adolescents with substance use issues, and the need for continuing education to reduce stigma
Electrospun nanofiber composite membranes based on cellulose acetate/nano-zeolite for the removal of oil from oily wastewater
No full textEfficient separation of oil from oily wastewater is a great environmental challenge. Nano- and microfiber electrospun membranes can be used to remove oils and organics in wastewater through the nano- or microfiltration process. Due to the low degree of fouling and relatively high-water flux, electrospun membranes exhibit promising applications for wastewater treatment. This paper reports the fabrication and evaluation of electrospun membranes based on cellulose acetate (CA) and nano-zeolites. By carefully controlling different parameters, CA and CA/zeolite electrospun membranes were fabricated. Various characterization techniques were used to evaluate the electrospun membranes. The optimum CA concentration to fabricate the membrane was 16% (w/v), and 10% (w/w) nano-zeolites were successfully incorporated into the membrane. The scanning electron micrographs revealed that the fabricated membranes had a fiber diameter range of 100–3000 nm. The apparent pore sizes of the as-fabricated membranes were in micro-/submicrometer. The zeolite nanoparticles were observed to be incorporated successfully throughout the membranes and the presence of the zeolites was confirmed using the EDX spectrum and EDX elemental mapping. The resulting membranes exhibited super hydrophilicity. The final quality of filtered water was investigated by measuring the oil droplets using optical microscopy, and the absorbance of unfiltered and filtered water was measured using UV–Vis spectrophotometer. The microfiltration process allowed the water phase to pass through the CA and CA/zeolite electrospun membranes which repelled the dispersed oil droplets restricting them to stay on the surface. The oil separation efficiency was up to 97%. Owing to biodegradability, non-toxic properties, and cost-effectiveness of the fabrication process, the membranes can be potentially used in microfiltration to remove oil in oily wastewater
(R1239) A New Type II Half Logistic-G family of Distributions with Properties, Regression Models, System Reliability and Applications
Get PDFThis study proposes a new family of distributions based on the half logistic distribution. With the new family, the baseline distributions gain flexibility through additional shape parameters. The important statistical properties of the proposed family are derived. A new generalization of the Weibull distribution is used to introduce a location-scale regression model for the censored response variable. The utility of the introduced models is demonstrated in survival analysis and estimation of the system reliability. Three data sets are analyzed. According to the empirical results, it is observed that the proposed family gives better results than other existing models
(R1488) Transformation of Glucokinase under Variable Rate Constants and Thermal Conditions: A Mathematical Model
Get PDFThe glucokinase (GK) in cells plays a pivotal role in the regulation of carbohydrate metabolism and acts as a sensor of glucose. It helps us to control glucose levels during fast and food intake conditions through triggering shifts in metabolism or cell functions. Various forms of hypoglycaemia and hyperglycaemia occur due to the transformations of the gene of the Glucokinase. The mathematical modelling of enzyme dynamics is an emerging research area to serve its role in biological investigations. Thus, it is imperative to establish a mathematical model to understand the kinetics of native and denatured forms of enzyme-GK under thermal stress with respect to time. The formulation of the current model is based on the number of non-linear ordinary differential equations with suitable initial and boundary conditions. The transformations of glucokinase were studied using mathematical and computational simulations in order to estimate the concentration of native and denatured enzyme forms with respect to different rate constants and under various thermal changes. The results obtained in this model were verified with the empirical outcome of Sanchez Ruiz et al. and Weinhouse for the validity and efficacy of the formulated model
(R1519) On Some Geometric Properties of Non-null Curves via its Position Vectors in \mathbb{R}_1^3
Get PDFIn this work, the geometric properties of non-null curves lying completely on spacelike surface via its position vectors in the dimensional Minkowski 3-space \mathbb{R}_1^3 are studied. Also, we give a few portrayals for the spacelike curves which lie on certain subspaces of \mathbb{R}_1^3. Finally, we present an application to demonstrate our insights
(R1494) Approximate Solutions of the Telegraph Equation
Get PDFIn this paper the initial boundary value problems for the linear telegraph equation in one and two space dimensions are considered. To find approximate solutions, a recently proposed optimization-free approach that utilizes artificial neural networks with one hidden layer is used, in which the connecting weights from the input layer to the hidden layer are chosen randomly and the weights from the hidden layer to the output layer are found by solving a system of linear equations. One of the advantages of this method, in comparison to the usual discretization methods for the two-dimensional linear telegraph equation, is that this artificial neural network method does not require time discretization and it produces the approximate solution in a closed analytic form. A numerical study on several examples for which the exact solutions are known is conducted and the dependence of the maximum absolute error and the root-mean-square deviation error on the size of the training set and on the number of nodes in the hidden layer is explored. It is shown numerically that, in general, both errors tend to decrease with the increase of the size of the training set and the size of the hidden layer
The Overrepresentation of Youth with Disabilities in the Juvenile Justice System
Get PDFThis paper discusses the contributing factors and effects of youth[VD(1] with disabilities in the juvenile justice system. The disabilities discussed will be those of social, emotional, learning, and behavioral; presenting disconnections between these children, youth, educational system, and juvenile justice system. [VD(2] The juvenile justice system encompasses youth with behavior attributed to their disability that has been criminalized and thereby labeled as a delinquent. A juvenile delinquent is defined as a minor who…commits anti-social or criminal acts, like vandalism or violence (Dictionary.com, 2016). Such behavior could be disorderly conduct or temper tantrums that is criminalized as assault or general disruption and that typically occurs in a classroom or school setting resulting in temporary arrest or detention by police officers. Statistics, research mechanisms, and data vary state-to-state, but some federal data show that kids with disabilities are overrepresented in the state\u27s detention facilities (Mader & Butrymowicz, 2014)
Novel Model Predictive Control For Electrical Machine Drives Considering Circuit Faults
No full textElectrical machine drives play a vital role in various industrial applications. Hence, its control system design became more significant in the last decades. In various high power and high-efficiency machine drives, continuous operation necessitates despite the fault. Fault-tolerant control is an effective solution to enhance the reliability of the machine drives. Concurrently, Model Predictive Control (MPC) is an optimal control algorithm developed for constrained control of Multi-Input-Multi-Output (MIMO) systems. MPC can handle MIMO systems, which can incorporate several constraints in the form of equalities and inequalities. In this dissertation, a Novel Model Predictive Control (NMPC) for a machine drive considering a real-time fault diagnostic method for Insulated Gate Bipolar Transistor ((IGBT) faults in an inverter has been presented. The proposed NMPC method can also reduce the stator current’s steady errors and enhance the robustness of current control loops effectively under parameter mismatch and permanent magnet demagnetization.
Solutions exist that address motor and motor drive systems’ faults, such as singlephase, three-phase, and permanent magnet demagnetization faults. These solutions, however, are not satisfactory. For example, they do not address the control overshoot and fast-tracking of the drive system.
In this dissertation, a novel model predictive control (NMPC) method is the solution that assures the system’s better performance. Since there is no existing research that describes the common MPC for all the different types of faults in PMSM drives, a novel model predictive controller (NMPC) is designed for a permanent magnet synchronous motor (PMSM) drive considering single-phase fault, three-phase fault, and demagnetization fault. First, the mathematical modeling of the PMSM drive for the prefault and post-fault operation has been introduced, followed by the advancement of the NMPC employing to predict the current in a discrete-time calculation. The phase current can be estimated at the next sampling step to compensate for the current errors, with the modification of three-phase currents of the motor. Concurrently, the machine’s fault diagnosis carried out for the pre-fault and post-fault conditions using MATLAB/Simulink. Ultimately, the machine’s speed responses using traditional control methods compared with the NMPC under different speed references for different fault conditions. The proposed algorithm has been implemented using the Lucas Nulle Servo Drive system with MATLAB/Simulink. The complete analysis, simulation, and experimental results illustrate that the adoption of NMPC improves the speed-tracking performance and provides minimal fault clearance time compared to the existing controllers
Weighted Geometric Mean and its Properties
Get PDFVarious means (the arithmetic mean, the geometric mean, the harmonic mean, the power means) are often used as central tendency statistics. A new statistic of such type is offered for a sample from a distribution on the positive semi-axis, the γ-weighted geometric mean. This statistic is a certain weighted geometric mean with adaptive weights. Monte Carlo simulations showed that the γ-weighted geometric mean possesses low variance: smaller than the variance of the 0.20-trimmed mean for the Lomax distribution. The bias of the new statistic was also studied. We studied the bias in terms of nonparametric confidence intervals for the quantiles which correspond of our statistic for the case of the Lomax distribution. Deviation from the median for the γ-weighted geometric mean was measured in terms of the MSE for the log-logistic distribution and the Nakagami distri- bution (the MSE for the γ-weighted geometric mean was comparable or smaller than the MSE for the sample median)