768 research outputs found

    Modified discrete Fourier transform algorithm for protection of shunt compensated distribution line

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    Introduction. The response time of the relay plays vital role when fault occurs on the line. Various algorithms are adopted to increase the sampling rate of the relay which, in turn, improves the response time. Methods. Discrete Fourier transform and modified discrete Fourier transform are the two algorithms used to calculate the fundamental frequency phasor of the signal required by the relay to initiate trip command. It is known that discrete Fourier transform takes four to five cycles to produce the fundamental frequency phasor but it fails to deal with the decaying DC component. On the other hand, modified discrete Fourier transform improves the response time by removing the decaying DC component along with the other harmonics in just one cycle and a few samples. The aim of this paper is to cover discrete Fourier transform and modified discrete Fourier transform algorithms to analyze the performance of the three overcurrent and one earth fault relaying scheme for different types of faults occurring in the distribution system. Methodology. The concept of three overcurrent and one earth fault scheme is also explained in this paper for protection of shunt-compensated distribution system. The scheme is designed for variable power factor. MATLAB/Simulink is used as the software tool to validate the results obtained for various types of faults occurring in the system. The results are represented graphically to illustrate the time of response of the protection scheme when shunt compensators are connected at the receiving end of distribution network.Вступ. Час спрацювання реле відіграє життєво важливу роль при виникненні несправності на лінії. Для збільшення частоти дискретизації реле застосовуються різні алгоритми, що, своєю чергою, покращує час спрацювання. Методи. Дискретне перетворення Фур’є та модифіковане дискретне перетворення Фур’є – це два алгоритми, які використовуються для розрахунку вектора основної частоти сигналу, необхідного для реле подачі команди на відключення. Відомо, що для отримання вектора основної частоти дискретного перетворення Фур’є потрібно від чотирьох до п'яти циклів, але воно не справляється з постійною складовою струму, що згасає. З іншого боку, модифіковане дискретне перетворення Фур’є покращує час спрацювання, видаляючи постійну складову струму, що згасає, разом з іншими гармоніками всього за один цикл і кілька вибірок. Мета цієї статті полягає в тому, щоб охопити алгоритми дискретного перетворення Фур’є та модифікованого дискретного перетворення Фур’є для аналізу характеристик трьох схем реле максимального струму та однієї схеми захисту від замикань на землю для різних типів несправностей, що виникають у розподільчій системі. Методологія. У статті  пояснюється також концепція трьох схем перевантаження по струму і однієї схеми замикання на землю для захисту розподільчої системи з паралельною компенсацією. Схема розрахована на змінний коефіцієнт потужності. MATLAB/Simulink використовується як програмний інструмент для перевірки результатів, отриманих для різних типів відмов, що виникають у системі. Результати представлені графічно, щоб проілюструвати час спрацьовування схеми захисту, коли шунтуючі компенсатори підключені на приймальному кінці розподільної мережі

    ONE FACTOR RESPONSE SURFACE METHODOLOGY (RSM) FOR THE OPTIMIZATION OF ORAL VENLAFAXINE HCL CONTROLLED RELEASE ORGANOGEL

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    Objective: The aim of this study was to develop the oral Venlafaxine HCl controlled-release organogel (organogel–CR) by using one-factor response surface methodology (RSM). Methods: In this study, Drug-excipient compatibility was evaluated by FT-IR. A total of 14 experimental runs were carried out employing the detailed conditions designed by a single factor completely randomized design based on the response surface methodology was used to check the concentration effect of 12-Hydroxy stearic acid (12-HSA) at different cooling rates on drug release at 10 h (Q10) and after 12 h (Q12). Multiple linear regression analysis, analysis of variance (ANOVA) and graphical representation of the influence factor were performed by using design expert 12. The developed organogel was also evaluated for viscosity, strength, transition temperature, diffusivity and Scanning electron microscopy (SEM). Prepared organogel was filled in the capsule and investigated for weight variation, drug content, erosion of organogel and In vitro drug release study. Results: FT-IR results showed that there was no chemical interaction between the drug and excipients. The SEM photograph indicates that the developed organogel was highly viscous with 3D network structure. The experimental confirmation tests showed a correlation between the predicted and experimental responses (R2 = 0.9937 and 0.9709). The results of ANOVA suggested that calculated F values of all dependent variables are greater than tabulated values. The optimal point obtained was located in the valid region and the optimum in vitro release of the predicted batch containing 7.9% concentration of 12-HSA with gradual cooling rate. To validate the evolved mathematical models, a checkpoint was selected and its desirability value was found to be 0.866. Conclusion: Oral controlled release Venlafaxine HCl organogel fix the problem of repeated dosing and patient noncompliance

    Effect of Calorie Restriction on Circadian Rhythms of Glycolytic Enzymes in Mice

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    Multicellular and unicellular organisms have all proven to exhibit circadian rhythms which persist over approximately 24 hours. This internal time keeping system is responsible for regulating the body\u27s biological functions. It has been known that calorie restriction effects circadian rhythms by causing a response in clock gene expression. These clock genes react to food intake and become either upregulated or downregulated accordingly. With glycolysis being a biological pathway that occurs in most organisms, measuring glycolytic gene expression in the liver tissue of young male mice becomes of interest. More specifically, hexokinase, PFK-1, and pyruvate kinase are the enzymes of interest. By analyzing the expression of key regulatory glycolytic genes in the liver tissue of mice, the importance of how diet effects circadian rhythm will be revealed. Results have shown that calorie restriction has some effect on circadian rhythms of glycolytic gene expression. We propose that if calorie restriction effects the circadian rhythms in the expression of glycolytic genes, then a down regulation in the profiles of ad libitum mice will be seen and an upregulation of calorie restricted mice\u27s genes will be shown.https://engagedscholarship.csuohio.edu/u_poster_2016/1008/thumbnail.jp

    Endogenous transforming growth factor β1 suppresses inflammation and promotes survival in adult CNS

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    Transforming growth factor β1 (TGFβ1) is a pleiotropic cytokine with potent neurotrophic and immunosuppressive properties that is upregulated after injury, but also expressed in the normal nervous system. In the current study, we examined the regulation of TGFβ1 and the effects of TGFβ1 deletion on cellular response in the uninjured adult brain and in the injured and regenerating facial motor nucleus. To avoid lethal autoimmune inflammation within 3 weeks after birth in TGFβ1-deficient mice, this study was performed on a T- and B-cell-deficient RAG2-/- background. Compared with wild-type siblings, homozygous deletion of TGFβ1 resulted in an extensive inflammatory response in otherwise uninjured brain parenchyma. Astrocytes increased in GFAP and CD44 immunoreactivity; microglia showed proliferative activity, expression of phagocytosis-associated markers [αXβ2, B7.2, and MHC1 (major histocompatibility complex type 1)], and reduced branching. Ultrastructural analysis revealed focal blockade of axonal transport, perinodal damming of axonal organelles, focal demyelination, and myelin debris in granule-rich, phagocytic microglia. After facial axotomy, absence of TGFβ1 led to a fourfold increase in neuronal cell death (52 vs 13%), decreased central axonal sprouting, and significant delay in functional recovery. It also interfered with the microglial response, resulting in a diminished expression of early activation markers [ICAM1 (intercellular adhesion molecule 1), α6β1, and αMβ2] and reduced proliferation. In line with axonal and glial findings in the otherwise uninjured CNS, absence of endogenous TGFβ1 also caused an ∼10% reduction in the number of normal motoneurons, pointing to an ongoing and potent trophic role of this anti-inflammatory cytokine in the normal as well as in the injured brain. Copyright © 2007 Society for Neuroscience

    Thermal, structural and degradation properties of an aromatic-aliphatic polyester built through ring-opening polymerisation

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    The novel biodegradable aromatic–aliphatic polyester, poly(2-(2-hydroxyethoxy)benzoate), was explored through thermal analysis, X-ray diffraction, dynamic mechanical analysis and comparative bio and catalysed degradation.</p

    Inhibition of Neuromuscular Contractions of Human and Rat Colon by Bergamot Essential Oil and Linalool: Evidence to Support a Therapeutic Action

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    Bergamot essential oil (BEO) added to food and drink promotes a citrus flavour. Folklore suggests benefits on gastrointestinal functions but with little supporting evidence. BEO and major constituents (linalool, limonene, linalyl acetate) were therefore examined for any ability to influence neuromuscular contractions of human and rat colon. Circular muscle strips (macroscopically-normal human colon obtained following ethical approval at cancer surgery; Sprague–Dawley rats) were suspended in baths (Krebs solution; 37 °C; 5% CO2 in O2) for measurement of neuronally-mediated contractions (prevented by tetrodotoxin or atropine) evoked by electrical field stimulation (5 Hz, 0.5 ms pulse width, 10s/minute, maximally-effective voltage), or contractions evoked by KCl (submaximally-effective concentrations). BEO and each constituent concentration dependently inhibited neuronally-mediated and KCl-induced contractions. In human: apparent pIC50 for BEO (volume/volume Krebs), respectively, 3.8 ± 0.3 and 4.4 ± 0.3; Imax 55.8% ± 4.2% and 37.5% ± 4.2%. For the constituents, the rank order of potency differed in human (linalool &gt; limonene &gt;&gt; linalyl-acetate) and rat colon (linalyl-acetate &gt; limonene = linalool), but rank order of efficacy was similar (linalool &gt;&gt; (BEO) = linalyl-acetate &gt;&gt; limonene). Thus, linalool had high efficacy but greater potency in human colon (Imax 76.8% ± 6.9%; pIC50 6.7 ± 0.2; n = 4) compared with rat colon (Imax 75.3% ± 1.9%; pIC50 5.8 ± 0.1; n = 4). The ability of BEO and linalool to inhibit human colon neuromuscular contractility provides a mechanism for use as complementary treatments of intestinal disorders

    Dually sensitive dextran-based micelles for methotrexate delivery

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    Temperature-sensitive polymeric micelles were prepared from dextran grafted with poly(N-isopropylacrylamide) (PNIPAAm) or polyethylene glycol methyl ether (PEGMA) via controlled radical polymerization and evaluated as delivery systems of the anticancer drug methotrexate (MTX). Polymer-grafting was carried out after introduction of initiating groups onto the polysaccharide backbone, without the need for protection of hydroxyl groups and avoiding the use of toxic solvents. Temperature-responsive dextran-based copolymers were designed to exhibit self-aggregation behaviour, affinity for MTX and high cellular internalization. In addition, some grafted polymers incorporated 2-aminoethyl methacrylate to reinforce MTX encapsulation in the micelles by means of ionic interactions. Dextran-based micelles were cytocompatible and had an appropriate size to be used as drug carriers. MTX release was dependent on the pH and temperature. The combination of poly(2-aminoethylmethacrylate) and PNIPAAm with the dextran backbone permitted the complete release of MTX at normal physiological temperature. Co-polymer micelles were highly internalized by tumour cells (CHO-K1) and, when loaded with MTX, led to enhanced cytotoxicity compared to the free drug
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