75 research outputs found
Performance Analysis of DTC-SVM Sliding Mode Controllers-Based Parameters Estimator of Electric Motor Speed Drive
This paper is concerned with a framework which unifies direct torque control space vector modulation (DTC-SVM) and variable structure control (VSC). The result is a hybrid VSC-DTC-SVM controller design which eliminates several major limitations of the two individual controls and retains merits of both controllers. It has been shown that obtained control laws are very sensitive to variations of the stator resistance, the rotor resistance, and the mutual inductance. This paper discusses the performances of adaptive controllers of VSC-DTC-SVM monitored induction motor drive in a wide speed range and even in the presence of parameters uncertainties and mismatching disturbances. Better estimations of the stator resistance, the rotor resistance, and the mutual inductance yield improvements of induction motor performances using VSC-DTC-SVM, thereby facilitating torque ripple minimization. Simulation results verified the performances of the proposed approach
Panniculite au cours dâun traitement dâune dermatomyosite par du mĂ©thotrexate
La panniculite est une manifestation rare au cours des dermatomyosites (DM). Lâapparition dâune panniculite au cours dâun traitement par du mĂ©thotrexate (MTX) est exceptionnelle et nâa Ă©tĂ© dĂ©crite que dans 3 cas. Nous rapportons lâobservation dâune patiente ĂągĂ©e de 50 ans atteinte dâune DM diagnostiquĂ©e en 1997 et traitĂ©e par une corticothĂ©rapie avec une Ă©volution favorable aux plans clinique et biologique. A lâoccasion dâune rechute 2 ans plus tard, la corticothĂ©rapie a Ă©tĂ© majorĂ©e et du mĂ©thotrexate Ă une dose hebdomadaire de 7,5 mg a Ă©tĂ© rajoutĂ©. LâĂ©volution Ă©tait rapidement favorable. Dix huit mois plus tard, la patiente prĂ©sentait de multiples nodules sous cutanĂ©s siĂ©geant aux 4 membres et aux fesses, dont lâexamen anatomopthologique concluait Ă une panniculite. Il nâexistait aucun signe dâĂ©volutivitĂ© de la DM. La dose de prĂ©dnisone a Ă©tĂ© augmentĂ©e Ă 0,5 mg/kg/j toujours en association au MTX mais sans aucune amĂ©lioration. Le MTX a Ă©tĂ© arrĂȘtĂ© et les lĂ©sions cutanĂ©es ont complĂštement disparu en 2 mois sans aucune rĂ©cidive avec un recul actuel de 42 mois. Notre observation est particuliĂšre par la survenue dâune panniculite chez une patiente ayant une DM traitĂ©e par du MTX et illustre la difficultĂ© diagnostique. Cette entitĂ© doit ĂȘtre connue malgrĂ© son caractĂšre exceptionnel puisque lâarrĂȘt du MTX induit en gĂ©nĂ©ral la disparition des nodules sous cutanĂ©s.Pan African Medical Journal 2016; 2
Green and Fast Extraction of Chitin from Waste Shrimp Shells: Characterization and Application in the Removal of Congo Red Dye
Due to their detrimental and carcinogenic effects, synthetic organic dyes pose significant environmental and health risks. Consequently, addressing the bioremediation of industrial wastewater containing these organic dyes has become an urgent environmental concern. The adsorption using low-cost and green materials is one of the best alternative techniques for the removal of dyes. This study aims to investigate the use of chitin to eliminate Congo red (CR), an anionic dye, from wastewater. The chitin was produced from shrimp shell in a quick and environmentally friendly manner by utilizing a co-solvent (glycerol/citric acid (GLC)). The resulting adsorbent was characterized through various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and FT-IR spectroscopy. The effectiveness of CR removal with chitin was studied with respect to contact time, adsorbent dose, initial pH, equilibrium isotherms, and kinetic and thermodynamic parameters. It was observed that variations in the dye concentration and pH significantly influenced the removal of CR with chitin. Under optimal operating conditions (pH = 7, contact time = 130 min, temperature = 50 °C), the adsorption capacity reached 29.69 ± 0.2 mg/g. The experimental data revealed that CR adsorption onto a chitin adsorbent is better represented by a Langmuir isotherm
Combined Neutrase-Alcalase Protein Hydrolysates from Hazelnut Meal, a Potential Functional Food Ingredient
Consumers\u27 interest in functional foods has significantly increased in the past few years. Hazelnut meal, the main valuable byproduct of the hazelnut oil industry, is a rich source of proteins and bioactive peptides and thus has great potential to become a valuable functional ingredient. In this study, hazelnut protein hydrolysates obtained by a single or combined hydrolysis by Alcalase and Neutrase were mainly characterized for their physicochemical properties (SDS-PAGE, particle size distribution, Fourier-transform infrared (FTIR) spectroscopy, molecular weight distribution, etc.) and potential antiobesity effect (Free fatty acid (FFA) release inhibition), antioxidant activity (DPPH and ABTS methods), and emulsifying properties. The impact of a microfluidization pretreatment was also investigated. The combination of Alcalase with Neutrase permitted the highest degree of hydrolysis (DH; 15.57 \ub1 0.0%) of hazelnut protein isolate, which resulted in hydrolysates with the highest amount of low-molecular-weight peptides, as indicated by size exclusion chromatography (SEC) and SDS-PAGE. There was a positive correlation between the DH and the inhibition of FFA release by pancreatic lipase (PL), with a significant positive effect of microfluidization when followed by Alcalase hydrolysis. Microfluidization enhanced the emulsifying activity index (EAI) of protein isolates and hydrolysates. Low hydrolysis by Neutrase had the best effect on the EAI (84.32 \ub1 1.43 (NH) and 88.04 \ub1 2.22 m2/g (MFNH)), while a negative correlation between the emulsifying stability index (ESI) and the DH was observed. Again, the combined Alcalase-Neutrase hydrolysates displayed the highest radical scavenging activities (96.63 \ub1 1.06% DPPH and 98.31 \ub1 0.46% ABTS). FTIR results showed that the application of microfluidization caused the unfolding of the protein structure. The individual or combined application of the Alcalase and Neutrase enzymes caused a switch from the ÎČ-sheet organization of the proteins to α-helix structures. In conclusion, hazelnut meal may be a good source of bioactive and functional peptides. The control of its enzymatic hydrolysis, together with an appropriate pretreatment such as microfluidization, may be crucial to achieve the best suitable activity
Water-soluble polysaccharides from Opuntia stricta Haw. fruit peels: Recovery, identification and evaluation of their antioxidant activities
Opuntia stricta Haw. is considered as one of the most common cactus plant growing in Tunisia. Extracting valuable compounds from its fruit peel, considered as by-product, is drawing more and more attention, making it on the verge of commercialization. Water-soluble polysaccharides were extracted from Opuntia stricta Haw. peels, and their chemical composition assessed using thin layer chromatography. The antioxidant activities of the extracted polysaccharides were assessed using 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity, total antioxidant activity and reducing power capacity. The extraction yield of water-soluble polysaccharides was 7.53±0.86%. The chemical composition revealed the presence of rhamnose, arabinose, glucose, mannose, galactose and galacturonic acid. The infra-red spectroscopic analysis showed a similar structure to that of Opuntia ficus-indica polysaccharide peels. Additionally, the extracted polysaccharides exhibited high antioxidant activities. In fact, the free radical scavenging activity (half inhibition concentration = 6.5 mg ml-1 with 94.9% inhibition at 50 mg ml-1), the total antioxidant activity (100 Όg ascorbic acid equivalent at 50 mg polysaccharides) and the reducing power capacity (absorbance 700 nm = 0.7 at 50 mg ml-1), appeared to be interesting compared to natural and synthetic antioxidants. Therefore, water-soluble polysaccharides from Opuntia stricta Haw. fruit peels could be a natural alternative to replace synthetic antioxidants
Interactions between Hazelnut (Corylus avellana L.) Protein and Phenolics and In Vitro Gastrointestinal Digestibility
In this study, we investigated the formation of proteinâphenolic complexes from dephenolized hazelnut meal protein isolates (dHPI) and hazelnut skin phenolic extracts (HSE) and their effects on the bioaccessibility of both hazelnut proteins and phenolics. The dHPIâHSE complexes were of considerable size and were dependent on HSE concentration due to aggregation. Although catechin was the main component of HSE, it did not cause aggregation, except for a slight rise in particle size. According to fluorescence quenching, the hazelnut proteinâphenolic extract complex had a linear SternâVolmer plot expressing static quenching between 0â0.5 mM concentration; the interaction was mainly dependent on hydrogen bonding and van der Waals forces (ÎH < 0 and ÎS < 0), and the reaction was spontaneous (ÎG < 0). According to Fourier transform infrared (FTIR) spectroscopy results, higher phenolic extract concentration caused an increase in irregular structures in hazelnut protein, while the lowest catechin and phenolic concentration altered the regular structure. Skin extracts did not alter the digestibility of dephenolized proteins, but dephenolization reduced the degree of hydrolysis by pancreatin. The formation of the proteinâphenolic complex had a beneficial effect on the bioaccessibility of hazelnut skin phenols, predominantly those on the galloylated form of the catechins, such as gallocatechin gallate and epigallocatechin gallate. Thus, the bioaccessibility and antioxidant activity analysis results showed that proteinâphenolic complexes obtained from hazelnut meal and skin may promote the transition of phenolic compounds from the gastrointestinal tract without degradation
Pulmonary Hyalinising Granuloma: A report of two cases
ABSTRACT: Pulmonary hyalinising granuloma (PHG) is a rare fibrosclerosing inflammatory lung condition of unknown aetiology. It is characterised by solitary or multiple pulmonary nodules that are usually found incidentally while imaging the chest for other reasons. We report two cases of histologically proven PHG diagnosed at the Royal Hospital, Muscat, Oman. The first case was a 71-year-old male patient who presented in 2010 with a dry cough, weight loss and bilateral pulmonary nodules. The second case was a 58-year-old male patient who presented in 2012 and was found to have incidental bilateral pulmonary nodules on chest X-ray. Both patients were started on prednisolone and on follow-up the PHG nodules remained stable. Although there is no definitive treatment, PHG generally has an excellent prognosis.Keywords: Granuloma; X-Ray Computed Tomography; Multiple Pulmonary Nodules; Lung; Case Report; Oman
Effects of playing surface on physical, physiological and perceptual responses to a repeated sprint ability test: natural grass versus artificial turf
Purpose: The effect of playing surface on physical performance during a repeated sprint ability (RSA) test, and the mechanisms for any potential playing-surface-dependent effects on RSA performance, is equivocal. The purpose of this study was to investigate the effect of natural grass (NG) and artificial turf (AT) on physical performance, ratings of perceived exertion (RPE), feeling scale (FS) and blood biomarkers related to anaerobic contribution [lactate (Lac)], muscle damage [creatine kinase (CK) and lactate dehydrogenase (LDH)], inflammation [c-reactive protein (CRP)] and immune function [neutrophils (NEU), lymphocytes (LYM) and monocytes (MON)] in response to a RSA test. Methods: Nine male professional football players from the same regional team completed two sessions of RSA testing (6 à 30 s interspersed by 35 s recovery) on NG and AT in a randomized order. During the RSA test, total (sum of distances) and peak (highest distance covered in a single repetition) distance covered were determined using a measuring tape and the decrement in sprinting performance from the first to the last repetition was calculated. Before and after the RSA test, RPE, FS, and blood [Lac], [CK], [LDH], [CRP], [NEU], [LYM] and [MON] were recorded in both NG and AT conditions. Results: Although physical performance declined during the RSA blocks on both surfaces (p=0.001), the distance covered declined more on NG (15%) compared to AT [11%; p=0.04, ES=-0.34, 95% CI (-1.21, 0.56)] with a higher total distance covered (+6 ± 2%) on AT [p=0.018, ES=1.15, 95% CI (0.16, 2.04)]. In addition, lower RPE [p=0.04, ES=-0.49, 95% CI (-1.36, 0.42)] and blood [Lac], [NEU] and [LYM] [p=0.03; ES=-0.80, 95% CI (-1.67, 0.14); ES=-0.16, 95% CI (-1.03, 0.72) and ES=-0.94, 95% CI (-1.82, 0.02), respectively)] and more positive feelings [p=0.02, ES=0.81, 95%CI (-0.13, 1.69)] were observed following the RSA test performed on AT compared to NG. No differences were observed in the remaining physical and blood markers. Conclusion: These findings suggest that RSA performance is enhanced on AT compared to NG. This effect was accompanied by lower fatigue perception and blood [Lac], [NEU] and [LYM], and a more pleasurable feeling. These observations might have implications for physical performance in intermittent team sports athletes who train and compete on different playing surfaces
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