Number of results to display per page
Search Results
632. Adsorbents for iron removal obtained from vermiculite
- Creator:
- Węgrzyn, Agnieszka, Chmielarz, Lucjan, Zjeżdżalka, Paweł, Andrzej Kowalczyk, Jabłońska, Magdalena, Baldrich Tolosa, Xavier, and Michalik, Marek
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, vermikulit, adsorpce, vermiculite, adsorption, acid treatment, iron removal, 7, and 551
- Language:
- English
- Description:
- In presented work, raw, expanded and acid treated vermiculites were used as low-cost and active adsorbents for reducing of environmental pollution with heavy metals. Acid treatment was performed at elevated temperature (95°C) for 2 and 24 h in solution of HNO3. Adsorption capacity towards Fe3+ was studied in column, semi-batch and batch mode. It was shown that all samples are effective in removal of heavy metals; however adsorption mechanism is based not only on ion exchange of interlayer cations but also precipitation/deposition processes. Starting material and modified samples as well as spent adsorbents were characterized with respect to the vermiculite structure using X-ray diffraction method., Agnieszka Węgrzyn, Lucjan Chmielarz, Paweł Zjeżdżalka, Andrzej Kowalczyk, Magdalena Jabłońska, Xavier Baldrich Tolosa and Marek Michalik., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
633. Adsorpcia arzeničnanov na pôdach: štúdium rýchlosti adsorpcie a adsorpčných izoteriem
- Creator:
- Hiller, Edgar
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- adsorption, freundlich isotherm, arsenates, kinetic equation, adsorpcia, Freundlichova izoterma, arzeničnany, and rýchlostná rovnica
- Language:
- Slovak
- Description:
- Kinetic and equilibrium studies of adsorption of arsenates As(V) were investigated in four soils from Slovakia. Using experimentally obtained adsorption isotherms of arsenates, the effect of selected soil properties on its adsorption was studied. The rate of As(V) adsorption was evaluated by three simple kinetic models: Elovich equation, modified Freundlich isotherm and pseudo-second order equation. It can be stated from experimentally obtained and calculated data that an increase in the initial As(V) concentration in solution resulted in a drop in the rate of As(V) adsorption and an increase in the time necessary for an attainment of the adsorption equilibrium. Results from equilibrium studies of As(V) adsorption fitted well to the Freundlich isotherm. The comparison of Freundlich coefficient kF with selected soil properties showed that capacity of particular soil for As(V) retention increased with increasing calcium carbonate content in given soil. The relation between CaCO3 content and kF coefficient was supported by highly positive correlation of dependence kF vs CaCO3, with R2 = 0.868. and Na štúdium rýchlosti adsorpcie arzeničnanov As(V) a ich adsorpčných izoteriem boli použité štyri vzorky pôd. Pomocou experimentálne získaných adsorpčných izoteriem As(V) bol sledovaný aj vplyv niektorých pôdnych vlastností na rozsah adsorpcie As(V). Rýchlosť adsorpcie As(V) bola zhodnotená použitím troch jednoduchých rýchlostných rovníc: Elovichovej rovnice, modifikovanej Freundlichovej izotermy a kinetickej rovnice pseudo-druhého poriadku. Namerané a vypočítané výsledky zo štúdia rýchlosti adsorpcie dokumentujú, že s rastúcou počiatočnou koncentráciou As(V) vo vodnom roztoku sa adsorpčná rýchlosť znížila a čas potrebný na dosiahnutie adsorpčnej rovnováhy sa zvýšil. Experimentálne získané adsorpčné izotermy As(V) veľmi dobre vyhovovali Freundlichovej adsorpčnej izoterme. Zo sledovaných chemických a fyzikálnych vlastností pôd mal na koeficient kF najväčší vplyv obsah uhličitanu vápenatého (CaCO3). Vzťah medzi obsahom CaCO3 a koeficientom kF sa potvrdil vysoko pozitívnou koreláciou (R2 = 0,868).
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
634. Adsorption of phenol and aniline by original and quaternary ammonium salts-modified montmorillonite
- Creator:
- Kostelníková, Hana, Petr Praus, and Turicová, Martina
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, adsorpce, montmorillonit, fenoly, anilin, adsorption, montmorillonite, phenols, aniline, intercalation, quaternary ammonium salts, 7, and 551
- Language:
- English
- Description:
- Adsorption of phenol and aniline onto original and with quaternary ammonium salts (QASs)-modified montmorillonite was described by sorption isotherms of type III and II, respectively. For the montmorillonite (MMT) modification - hydrophobisation, cetyltrimethyl- ammonium (CTMA) and tetramethylammonium (TMA ) cations were used. In comparison with phenol, aniline was adsorbed largely on original MMT but less on modified one. XRD pa tterns indicated that both aromatic compounds were intercalated in the MMT interlayer be ing perpendicularly oriented to silicate sheets. Alkyl chains of CTMA and TMA probably act as organic "pillars" stabilising the MMT tabular structure against exfoliation due to the intercalation with phenol and aniline of high concentrations., Hana Kostelníková, Petr Praus and Martina Turicová., and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
635. Adsorptive removal of aromatic compound by montmorillonite: application of factorial design analysis
- Creator:
- Geyikçi, Feza and Çoruh, Semra
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, montmorillonit, montmorillonite, factorial design analysis, phenol adsorption, 7, and 551
- Language:
- English
- Description:
- Phenolic compounds are common pollutants found particularly in the effluents from petroleum and petrochemical, coal conversion, and phenol producing industries. Due to their toxicity and carcinogenity, water and wastewater containing phenolic compounds must be treated before being used and discharged for receiving water bodies. There is a growing interest in using low-cost and commercially available materials for the adsorption of organic compounds. Clay minerals have great potential to remove phenols in water due to efficient sorbents which can be used as alternative adsorbents to replace the costly activated carbon. They are widely applied in many fields of adsorption technology including the removal of amines, metals, ketones, phosphates, chlorophyll, non-ionic contaminants, and organic pigments/dyes. Montmorillonitic smectites, {(Na,Ca)0.33(Al,Mg)2(Si4O10)-(OH)2.nH2O} are one of the natural clay minerals that have specific surface chemical properties. In this study, a factorial experimental design technique was used to investigate the adsorption of phenol from water solution on montmorillonite. Factorial design of experiments is employed to study the effect of three factors: pH (2.0 and 8.0), montmorillonite dosage (0.1 and 1.0 g/L) and initial low and high concentration (10 and 100 mg/L). The efficiency of phenol adsorption was determined after 60 min of treatment. Main effects and interaction effects of three factors were analyzed by using statistical techniques. A regression model was found to fit the experimental data very well. Through using the Student’s t-test, analysis of variance, F-test and lack of fit to define most important process variables affecting the percentage phenol adsorption., Feza Geyikçi and Semra Çoruh., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
636. Advanced genetic algorithms for engineering design problems
- Creator:
- Roupec, Jan
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- genetic algorithm, stochastic heuristic optimisation methods, evolutionary computing, and genetic operators
- Language:
- English
- Description:
- The study is analogy of the natural evolution and the technical object design dates back more than 50 years. The genetic algorithm (GA) is considered to be a stochastic heuristic (or meta-heuristic) optimisation method. The best use of GA can be found in solving multidimensional optimisation problems, for which analytical solutions are unknown (or extremely complex) and efficient numerical methods are also not known. GAs are inspired by adaptive and evolutionary mechanisms of live organisms, but they do not copy the natural process precisely. The paper describes the main terms, principles and original implementation details of GA. The main goal of this paper is to help readers to use proper GAs on the field of technical object design. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
637. Advanced Glycation End Products and Nutrition
- Creator:
- Marica Krajčovičová-Kudláčková, Katarína Šebeková, and Schinzel, R.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, Ne-carboxymethyllysine, Fructose, Vegetarian diet, Advanced glycation end products, 14, and 612
- Language:
- English
- Description:
- Advanced glycation end products (AGEs) may play an important adverse role in process of atherosclerosis, diabetes, aging and chronic renal failure. Levels of Ne-carboxymethyllysine and fluorescent AGE values were estimated in two nutritional population groups - alternative group (vegetarians - plant food, milk products, eggs) and traditional group (omnivorous subjects). Vegetarians have a significantly higher carboxymethyllysine content in plasma and fluorescent AGE values. Intake of proteins, lysine and monosaccharides as well as culinary treatment, consumption of food AGEs (mainly from technologically processed products) and the routes of Maillard reaction in organism are the substantial sources of plasma AGEs. Vegetarians consume less proteins and saccharides. Lysine intake is significantly reduced (low content in plant proteins). Subjects on alternative nutrition do not use high temperature for culinary treatment and consume low amount of technologically processed food. Fructation induced AGE fluorescence is greater as compared with that induced by glucose. It is due to higher participation of a more reactive acyclic form of fructose. Intake of vegetables and fruit with predominance of fructose is significantly higher in vegetarians. Comparison of nutrition and plasma AGEs in vegetarian and omnivorous groups shows that the higher intake of fructose in alternative nutrition of healthy subjects may cause an increase of AGE levels., M. Krajčovičová-Kudláčková, K. Šebeková, R. Schinzel., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
638. Advanced glycation end-product pentosidine accumulates in various tissues of rats with high fructose intake
- Creator:
- Mikulíková, K., Adam Eckhardt, Jaroslav Kuneš, Josef Zicha, and Ivan Mikšík
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, kardiovaskulární fyziologie, kolagen, cardiovascular physiology, collagen, AGEs (advanced glycation end-products), pentosidine, elastin, glycation, 14, and 612
- Language:
- English
- Description:
- The slowly metabolized proteins of the extracellular matrix, typically collagen and elastin, accumulate reactive metabolites through uncontrolled non-enzymatic reactions such as glycation or the products arising from the reaction of unsaturated long chain fatty acid metabolites (possessing aldehydic groups). A typical example of these non-enzymatic changes is the formation of advanced glycation end-products (AGEs), resulting from the reaction of carbohydrates with the free amino group of proteins. The accumulation of AGEs and the resulting structural alterations cause altered tissue properties (increased stiffness, reduced elasticity) that contribute to their reduced catabolism and to their aging. Posttranslational nonenzymatic modifications of the proteins of the extracellular matrix (the formation of a typical AGE product - pentosidine) were studied in three types of tissue of three rat strains subjected to a high-fructose diet. Chronic (three-week) hyperglycemia (resulting from fructose loading) caused a significant increase in pentosidine concentration mainly in the aorta and skin of the three rat strains (Lewis, Wistar and hereditary hypertriglyceridemic rats)., K. Mikulíková, A. Eckhardt, J. Kuneš, J. Zicha, I. Mikšík., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
639. Advanced glycation end-product pentosidine is not a relevant marker of disease activity in patients with rheumatoid arthritis
- Creator:
- Ladislav Šenolt, Martin Braun, Jiří Vencovský, Liliana Šedová, and Karel Pavelka
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, revmatologie, revmatoidní artritida, matrix, rheumatology, rheumatoid arthritis, pentosidine, advanced glycation end-product (AGE), cartilage oligomeric matrix protein (COMP), anti-CCP antibodies, 14, and 612
- Language:
- English
- Description:
- Advanced glycation end-product (AGE) pentosidine has previously been demonstrated in different tissues and body fluids. It was suggested as a novel marker for evaluating the pathologic activity in rheumatoid arthritis (RA). In this study we analyzed the relation between pentosidine and markers of inflammation, cartilage turnover, immune response, and disease status of RA. Using HPLC, we analyzed pentosidine in serum and synovial fluid from 39 patients with RA and in serum from 38 healthy controls. Cartilage oligomeric matrix protein (COMP) and antibodies to CCP (anti-CCP) were measured by ELISA. Clinical disease status was assessed by Disease Activity Score 28 (DAS 28) and functional status by Health Assessment Questionnaire (HAQ). We demonstrated significantly higher serum levels of pentosidine in RA patients in comparison with controls. Pentosidine in serum significantly correlated with pentosidine in synovial fluid. Serum pentosidine levels were associated with erythrocyte sedimentation rate (p<0.03) but not with CRP, COMP, anti-CCP antibodies, DAS 28, or HAQ. In contrast to previous studies, we could not show any correlation of pentosidine levels with inflammatory status, clinical disease activity, markers of immune response, or cartilage breakdown. However, AGEs can be suggested as important players participating in joint destruction rather than markers of disease activity., L. Šenolt, M. Braun, J. Vencovský, L. Šedová, K. Pavelka., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
640. Advanced Glycation End-Products and Advanced Oxidation Protein Products in Patients with Diabetes Mellitus
- Creator:
- Marta Kalousová, Jan Škrha, and Tomáš Zima
- Format:
- print, bez média, and svazek
- Type:
- article, studie, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, Advanced glycation end-products, Advanced oxidation protein products, Diabetes mellitu, Oxidative stress, 14, and 612
- Language:
- English
- Description:
- Accelerated glycoxidation takes part in the development of diabetic complications. We determined advanced glycation end-products (AGEs) and advanced oxidation protein products (AOPP) in the sera of 52 patients with diabetes mellitus (DM) - 18 with DM Type 1 and 34 with DM Type 2 and examined their relationship to the compensation of the disease. AGEs were estimated spectrofluorimetrically (350 nm/440 nm) whereas AOPP were determined spectro-photometrically (340 nm). AGEs were elevated only in DM Type 2 (DM2 5.11±1.15x103 AU/g vs controls 4.08±0.71x103 AU/g, p<0.001, vs DM1 4.14±0.86x103 AU/g, p<0.005, DM1 vs controls were not significant). AOPP were elevated significantly in both types of DM with higher levels in DM Type 2 (DM2 157.50±75.15 mmol/l vs healthy subjects 79.80±23.72 mmol/l, p<0.001, vs DM1 97.50±30.91 mmol/l, p<0.005, DM1 vs controls p<0.05). There was a tight correlation between AGEs and AOPP in both types of DM (DM1 r=0.75, DM2 r=0.47 (p<0.05)) and both AGEs and AOPP correlated with triglycerides. In DM Type 1 only, AGEs correlated with HbA1c r=0.47 (p<0.05) and with blood glucose. Slight but not significant differences in AGEs and AOPP levels were observed in patients with or without diabetic complications. Oxidative stress is increased in both types of DM, more in Type 2 where it contributes to the formation of glycoxidation products., M. Kalousová, J. Škrha, T. Zima., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public