Resistencia a los sulfatos de cementos portland con diversos contenidos de C3A

Not availableLa resistencia del cemento portland al ataque de los sulfatos depende, en su mayor parte, de su contenido en aluminato tricálcico, debido a que este compuesto forma, con el sulfato cálcico, una sal doble (3CaO . AI203. 3CaS04.3O-3IH2O), yendo acompañada la reacción por un aumento considerable de volumen. Si se forma esta sal durante el periodo de endurecimiento del cemento, las tensiones provocadas por los cambios de volumen pueden ser suficientemente elevadas para determinar la desintegración del hormigón. Sin embargo, cuanto mayor sea la cantidad de aluminato tricálcico formado durante el periodo inicial de endurecimiento, tanto menor será la posibilidad de que produzcan daños durante la fase final de curado, debido a que la cantidad de aluminato tricálcico que queda libre va siendo progresivamente menor, hasta que no queda nada en forma capaz de reaccionar con el sulfato cálcico

Voltammetric Determination of Thymol in Oregano Using CeO<inf>2</inf>-Modified Electrode in Brij® 35 Micellar Medium

© 2016 Springer Science+Business Media New YorkGlassy carbon electrode (GCE) modified with CeO2 nanoparticles dispersed in 0.01 M Brij® 35 (CeO2-Brij® 35/GCE) has been developed for the determination of thymol in micellar medium. Scanning electron microscopy (SEM) data confirm immobilization of the nanomaterial on the electrode surface. The electrooxidation of thymol on CeO2-Brij® 35/GCE is an irreversible diffusion-controlled process with participation of two electrons and two protons. Differential pulse voltammetry has been used for the quantification of thymol. The linear dynamic range of the thymol determination is 0.700–10.1 and 10.1–606 μM with the limits of detection and quantification 0.20 and 0.65 μM, respectively. The approach developed has been applied for the quantification of thymol in oregano spices using preliminary micellar extraction with Brij® 35. The results of voltammetric determination are in good agreement with the data of standard spectrophotometric method

Voltammetric Determination of Thymol in Oregano Using CeO<inf>2</inf>-Modified Electrode in Brij® 35 Micellar Medium

© 2016, Springer Science+Business Media New York.Glassy carbon electrode (GCE) modified with CeO2 nanoparticles dispersed in 0.01 M Brij® 35 (CeO2-Brij® 35/GCE) has been developed for the determination of thymol in micellar medium. Scanning electron microscopy (SEM) data confirm immobilization of the nanomaterial on the electrode surface. The electrooxidation of thymol on CeO2-Brij® 35/GCE is an irreversible diffusion-controlled process with participation of two electrons and two protons. Differential pulse voltammetry has been used for the quantification of thymol. The linear dynamic range of the thymol determination is 0.700–10.1 and 10.1–606 μM with the limits of detection and quantification 0.20 and 0.65 μM, respectively. The approach developed has been applied for the quantification of thymol in oregano spices using preliminary micellar extraction with Brij® 35. The results of voltammetric determination are in good agreement with the data of standard spectrophotometric method

Gas Chromatographic Determination of Diacetylmorphine with Mass Spectrometric Detection

The possibility of determining diacetylmorphine traces in various matrices by gas chromatography with mass spectrometric detection is demonstrated. Diacetylmorphine can be reliably determined by gas chromatography-mass spectrometry in the range 0.02-7.5 μg/mL. A procedure is developed for the quantitative determination of diacetylmorphine and its concomitants, including acetylated opioid derivatives, in forensic samples. The detection limit for diacetylmorphine without preconcentration is 0.01 μg/mL. The detection limit in the selective-ion monitoring mode with preconcentration is 1 × 10 -4 ×g/mL

Voltammetric Determination of Thymol in Oregano Using CeO<inf>2</inf>-Modified Electrode in Brij® 35 Micellar Medium

© 2016, Springer Science+Business Media New York.Glassy carbon electrode (GCE) modified with CeO2 nanoparticles dispersed in 0.01 M Brij® 35 (CeO2-Brij® 35/GCE) has been developed for the determination of thymol in micellar medium. Scanning electron microscopy (SEM) data confirm immobilization of the nanomaterial on the electrode surface. The electrooxidation of thymol on CeO2-Brij® 35/GCE is an irreversible diffusion-controlled process with participation of two electrons and two protons. Differential pulse voltammetry has been used for the quantification of thymol. The linear dynamic range of the thymol determination is 0.700–10.1 and 10.1–606 μM with the limits of detection and quantification 0.20 and 0.65 μM, respectively. The approach developed has been applied for the quantification of thymol in oregano spices using preliminary micellar extraction with Brij® 35. The results of voltammetric determination are in good agreement with the data of standard spectrophotometric method

Determination of the antioxidant capacity of the micellar extracts of spices in Brij® 35 medium by differential pulse voltammetry

© 2016, Pleiades Publishing, Ltd.It was established that the micellar extracts of spices are electrochemically active on a glassy carbon electrode modified with cerium dioxide nanoparticles in a 0.02 M Brij® 35 in the presence of a phosphate buffer solution (pH 7.4) under the conditions of differential pulse voltammetry. The number of oxidation steps and their potentials vary over a wide range depending on the type of spice. A number of the oxidation peaks of the micellar extracts of spices were identified based on the oxidation potentials of the following individual antioxidants: gallic acid, ferulic acid, p-coumaric acid, caffeic acid, rosmarinic acid, thymol, eugenol, vanillin, syringaldehyde, capsaicin, rutin, quercetin, catechin, tannin, and curcumin. The contribution of the main antioxidants to the amperometric response of the extracts was confirmed by the standard addition method. A procedure for the voltammetric determination of the antioxidant capacity of the extracts of spices based on the oxidation of their antioxidants was developed. The antioxidant capacity of spices was evaluated from the total area of the oxidation steps in units of gallic acid, whose analytical range, detection limit, and determination limit were 50–2490, 11.9, and 39.6 μM, respectively. Twenty types of spices were analyzed. Positive correlations of the antioxidant capacity with the ferric reducing power and the antioxidant activity (r = 0.8971 and 0.9127, respectively at rcrit = 0.497) were found

АНАЛИТИЧЕСКИЕ ВОЗМОЖНОСТИ СИСТЕМЫ ДВУХ АМПЕРОМЕТРИЧЕСКИХ БИОСЕНСОРОВ В ОПРЕДЕЛЕНИИ НЕКОТОРЫХ ПЕСТИЦИДОВ

The array of two amperometric biosensors based on the immobilized enzymes  cholinesterase  and cysteindesulfgidrase was proposed for the determination of triazine herbicides. The array is composed of 4 screen-printed electrodes made of platinum paste with the immobilized cholinesterase and cysteindesulfgidrase. The analytical characteristics of the determination of triazine herbicide propazine using the proposed biosensing system are evaluated. The liner concentration range is 1·10-5-1·10-10  mol/l for cholinesterase and 1·10-6-5·10-10 mol/l for cysteindesulfgidrase biosensor, and RSD does not exceed 0.057. Lower limit of detection for propazine is 9·10-11 for cholinesterase and 7·10-11  mol / l for cysteindesulfgidrase biosensors.Key words: biosensor, cholinesterase, cysteinedesulfhydrase,  platinum screen-printed electrodes,  triazine herbicides(Russian)DOI: http://dx.doi.org/10.15826/analitika.2013.17.2.014R.M. Varlamova, E.P. Medyantseva, G.R. Sahapova , H.C. Budnikov  Kazan (Volga Region) Federal University, A.M. Butlerov Institute of Chemistry, Kazan, Russian FederationДля определения гербицидов триазинового ряда предложена система двух амперометрических биосенсоров на единой подложке на основе иммобилизованных ферментов – холинэстеразы и цистеиндесульфгидразы. Основой биосенсоров служило устройство, состоящее из 4 печатных электродов, на рабочую поверхностью которых из платиносодержащей пасты иммобилизуется холинэстераза и цистеиндесульфгидраза. На примере пропазина показана возможность и оценены аналитические характеристики определения триазиновых гербицидов с помощью предлагаемой системы биосенсоров. Линейная зависимость между величиной тока и концентрацией пропазина наблюдается в интервалах концентраций 1·10-6-1·10-10 моль/л для холинэстеразного и 1·10-6-5·10-10 для цистеиндесульфгидразного биосенсоров с  погрешностью (Sr) не более 0.057. Нижняя граница определяемых концентраций для  пропазина составляет 9·10-11 для холинэстеразного и 7·10-11 моль/л для ЦДГ биосенсоров.Ключевые слова:биосенсор, холинэстераза, цистеиндесульфгидраза, платиновые screen-printed электроды,  триазиновые гербицидыDOI: http://dx.doi.org/10.15826/analitika.2013.17.2.01

Boosting the Power Generation in Wind and Hydro Power Production

When approaching a conventional wind turbine, the air flow is slowed down and widened. This results in a loss of turbine efficiency. In order to exploit wind or water flow power as effectively as possible, it was suggested that the turbine should be placed inside a shroud, which consists of 4 wing-shaped surfaces. Two internal air foils improve the turbine performance by speeding up the flow acting on the turbine blades, two external wings create a field of low pressure behind the turbine, thus, helping to draw more mass flow to the turbine and avoid the loss of efficiency due to flow deceleration. The system accumulates kinetic energy of the flow in a small volume where the smaller (and therefore, cheaper) turbine can be installed. A smaller system can be installed inside the bigger one, which would help to accumulate even more kinetic energy on the turbine. This method implies kinetic energy summation with local flow redistribution. Both experiments and CFD simulations demonstrate a significant increase in velocity and generated mechanical power in comparison to those for a bare turbine

АМПЕРОМЕТРИЧЕСКИЕ МОНОАМИНОКСИДАЗНЫЕ БИОСЕНСОРЫ НА ОСНОВЕ ГРАФИТОВЫХ ЭЛЕКТРОДОВ И ОКСИДА ГРАФЕНА КАК МОДИФИКАТОРА ПОВЕРХНОСТИ ДЛЯ ОПРЕДЕЛЕНИЯ НЕКОТОРЫХ АНТИДЕПРЕССАНТОВ Э.П.Медянцева, Д.В.Брусницын, Р.М.Варламова, Р.Р.Ситдикова, А.Н.Галявина

Novel monoamine oxidase amperometric biosensors based on screen-printed graphite electrodes modified with nanostructured material graphene oxide (GO) was developed for the determination of antidepressants («Melipraminum», «Coaxil» and «Fenazepam»).Response of the biosensor created is based on a combination of monoamine oxidase biochemical action towards biogenic amines (dopamine, serotonin) and electrochemical oxidation of hydrogen peroxide (a product of the enzymatic reaction) as well as the inhibition effect of the studied antidepressants of the immobilized enzyme. Тhe analytic signal is hydrogen peroxide oxidation current at potentials 0.7-0.75 V.The usage of chitosan acetate solution as a dispersant for carbon nanotubes and graphene oxide provides a more pronounced analytical biosensor signals compared to suspension in DMF. The antidepressants under investigation were determined within the wide range concentration of 1·10-4 - 1·10-8 M. The analytical capabilities of the GO-based biosensor with biosensor modified with carbon nanotubes in chitosan have been compared. GO-modified biosensor had certain advantages over biosensors modified with carbon nanotubes, in particular the higher sensitivity coefficient and lower detection limit.The application of acid-base titration as a reference method for determination on example of imipramine has shown the absence of systematic error in measurements using the developed biosensors.The biosensors developed can be applied for the control for residual amounts of drugs in biological fluids (urine) at 9·10-9 M as well as contents of active substance in pharmaceutical dosage forms.Keywords: biosensor, graphene oxide, carbon nanotubes, chitosan, antidepressants, monoamine oxidase, biological fluid (Russian)DOI: http://dx.doi.org/10.15826/analitika.2014.18.4.011 E.P. Medyantseva, D.V. Brusnitsyn, R.M. Varlamova, R.R. Sitdikova, A.N. Galiavina, G.K. BudnikovKazan` Federal University, Kazan`, Russian FederationREFERENCES1. Pietracci E. Simultaneous determination of new-generation antidepressants in plasma by gas chromatography–mass spectrometry. Forensic Toxicol., 2013, vol. 31, pp.124-132.2. Fernandez-Navarro J. J., Ruiz-Angel M. J., Garcıa-Alvarez-Coque M. C. Reversed-phase liquid chromatography without organic solvent for determination of tricyclic antidepressants. J. Sep. Sci., 2012, vol. 35, pp. 1303-1309.3. Davarani S., Najarian A., Nojavan S.М. Electromembrane extraction combined with gas chromatography for quantification of tricyclic antidepressants in human body fluids. Anal. Chim. Acta., 2012, vol. 725, pp. 51-56.4. Wang S. Development of enzyme-linked immunosorbent assay (ELISA) for the detection of neomycin residues in pig muscle, chicken muscle, egg, fish, milk and kidney. Meat Science, 2009, vol. 82, pp. 53-58.5. Liu S. Electrochemical immunosensor for salbutamol detection based on CS-Fe3O4-PAMAM-GNPs nanocomposites and HRP-MWCNTs-Ab bioconjugates for signal amplification. Sens. Actuators B, 2011, vol. 156, pp. 71-78.6. Song C. Rapid and sensitive detection of β-agonists using a portable fluorescence biosensor basedon fluorescent nanosilica and a lateral flow test strip. Biosens. Bioelectron., 2013, vol. 50, pp. 62-65.7. Mashkovskii M.D. Lekarstvennye sredstva. V 2 kn. Kn. 1 [Drug substance. Vol. 1]. M.: Novaia Volna, 2002, 540 p. (in Russian).8. Brondani D. Biosensor based on platinum nanoparticles dispersed in ionic liquid and laccase for determination of adrenaline. Sens. Actuators B, 2009, vol. 140, pp. 252-260.9. Djane D.J. Amperometric biosensor based on monoamine oxidase (MAO) immobilized in sol/gel film for benzydamine determination in pharmaceuticals. J. of Pharmaceutical and Biomedical Anal., 2003, vol. 33, pp. 983-990.10. Yang H. Reusable sensor based on high magnetization carboxyl-modified graphene oxide with intrinsic hydrogen peroxide catalytic activity for hydrogen peroxide and glucose detection. Biosens. Bioelectron., 2013, vol. 41, pp. 172-179.11. Chen B., Ma M., Su X. An amperometric penicillin biosensor with enhanced sensitivity based on co-immobilization of carbon nanotubes, hematein, and ß-lactamase on glassy carbon electrode. Anal. Chim. Acta, 2010, vol. 674, pp. 89-95.12. Olivé-Monllau R., Munoz-Pascual F.X., Baldrich E. Characterization and optimization of carbon nanotube electrodes produced by magnetic entrapment: Application to paracetamol detection. Sens. Actuators B, 2013, vol. 185, pp. 685-693.13. Shahrokhian S., Rastgar S. Electrochemical deposition of gold nanoparticles on carbon nanotube coated glassy carbon electrode for the improved sensing of tinidazole. Electrochim. Acta, 2012, vol. 78, pp. 422-429.14. Unnikrishnan B., Mani V., Chen S.-M. Highly sensitive amperometric sensor for carbamazepine determination based on electrochemically reduced graphene oxide–single-walled carbon nanotube composite film. Sensors and Actuators B, 2012, vol. 173, pp. 274-280.15. Wu C. Electrochemical sensor for toxic ractopamine and clenbuterol based on the enhancement effect of graphene oxide. Sensors and Actuators B, 2012, vol. 168, pp. 178 -184.16. Fanjul-Bolado P. Manufacture and evaluation of carbon nanotube modified screen-printed electrodes as electrochemical tools. Talanta, 2007, vol. 74, pp. 427-433.17. Li X., Jiang X. Electrostatic layer-by-layer assembled multilayer films of chitosan and carbon nanotubes. New Carbon Materials, 2010, vol. 25, no. 3, pp. 237-240.18. Gorkin V.Z. Aminoksidazy i ikh znachenie v meditsine [Aminoksidazes and their importance in medicine]. M.: Medicina, 1981. 336 p. (in Russian).19. Medyantseva E.P., Varlamova R.M., Gimaletdinova D.A., Budnikov G.K., Fattakhova A.N. [An amperometric monoamine oxidase biosensor for determining some antidepressants]. Zhurn. analit. khimii [Journal of Analytical Chemistry], 2008, vol. 63, no. 3, pp. 275-279 (in Russian).20. Medyantseva E.P., Varlamova R.M., Gimaletdinova D.A., Fattakhova A.N. Budnikov G.K. [The conditions of functioning of the amperometric biosensor based on monoamine oxidase]. Uchjonye zapiski Kaz. gos. un-ta. Estestvennye nauki [Proceedings of the Kazan State University. Natural science], 2006, vol. 148, no. 2, pp. 21-29 (in Russian).21. Danilova L.А. Analizy krovi i mochi [Blood and urine tests]. SPb.: Salit-Medkniga, 2003. 128 p. (in Russian).22. Shaidarova L.G., Romanova E.I., Chelnokova I.A., Gedmina A.V., Budnikov G.K. [Joint voltammetric determination of dopamine and uric acid at an electrode modified with self-assembled monolayer of cystamine with gold nanoparticles]. Zhurn. prikladn. khimii [J. of Applied Chem], 2011, vol.84, no. 2, pp. 222-228 (in Russian).23. Kushmanova O.D., Ivchenko G.M. Rukovodstvo k laboratornym zaniatiiam po biologicheskoi khimii [Guide to laboratory studies on biological chemistry]. M.: Medicina, 1983, 272 p. (in Russian).24. Berezov Т.Т., Korovkin B.F. Biologicheskaia khimiia [Biological chemistry]. М.: Medicine, 1998, 704 p. (in Russian).25. European pharmacopoeia 7.0, European Directorate for the Quality of Medicines HealthCare, 2010, vol. 2, pp. 2231-2232.Предложено использовать наноструктурированный материал оксид графена (ГО) в качестве модификатора поверхности планарных печатных графитовых электродов как основы амперометрических биосенсоров с иммобилизованной моноаминоксидазой для определения антидепрессантов («Мелипрамин», «Коаксил» и «Феназепам»). Функционирование предлагаемых биосенсоров основано на ингибирующей способности антидепрессантов воздействовать на каталитическую активность иммобилизованного фермента. Сопоставлены аналитические возможности предлагаемых биосенсоров c биосенсорами на основе электродов, модифицированных углеродными нанотрубками в хитозане и ДМФА. Предложенные биосенсоры можно использовать для контроля как остаточных количеств лекарственных препаратов в биологических жидкостях (урина) на уровне 9·10-9 М, так и лекарственного вещества в лекарственных формах.Ключевые слова: биосенсор, оксид графена, углеродные нанотрубки, хитозан, антидепрессанты, моноаминоксидаза, биологическая жидкостьDOI: http://dx.doi.org/10.15826/analitika.2014.18.4.011 ЛИТЕРАТУРА1. Simultaneous determination of new-generation antidepressants in plasma by gas chromatography–mass spectrometry / E. Pietracci [et al.] // Forensic Toxicol. 2013. V. 31. P. 124-132.2. Fernandez-Navarro J. J., Ruiz-Angel M. J., Garcıa-Alvarez-Coque M. C. Reversed-phase liquid chromatography without organic solvent for determination of tricyclic antidepressants // J. Sep. Sci. 2012. V. 35. P. 1303-1309.3. Davarani S., Najarian A., Nojavan S.М. Electromembrane extraction combined with gas chromatography for quantification of tricyclic antidepressants in human body fluids // Anal. Chim. Acta. 2012. V. 725. P. 51-56.4. Development of enzyme-linked immunosorbent assay (ELISA) for the detection of neomycin residues in pig muscle, chicken muscle, egg, fish, milk and kidney / S. Wang  [et al.] // Meat Science. 2009. V. 82. P. 53-58.5. Electrochemical immunosensor for salbutamol detection based on CS-Fe3O4-PAMAM-GNPs nanocomposites and HRP-MWCNTs-Ab bioconjugates for signal amplification  / S. Liu  [et al.] // Sens. Actuators B. 2011. V. 156. P. 71-78.6. Rapid and sensitive detection of β-agonists using a portable fluorescence biosensor basedon fluorescent nanosilica and a lateral flow test strip / C. Song [et al.] // Biosens. Bioelectron. 2013. V. 50. P. 62-65.7. Лекарственные средства. В 2 кн. Кн 1. / М.Д. Машковский; отв. ред. С.Б. Дивов. М.: Новая Волна, 2002. 540 с.8. Biosensor based on platinum nanoparticles dispersed in ionic liquid and laccase for determination of adrenaline / D. Brondani [et al.] // Sens. Actuators B. 2009. V. 140. P. 252-260.9. Amperometric biosensor based on monoamine oxidase (MAO) immobilized in sol/gel film for benzydamine determination in pharmaceuticals / D.J. Djane [et al.] // J. of Pharmaceutical and Biomedical Anal. 2003. V. 33. P. 983-990.10. Reusable sensor based on high magnetization carboxyl-modified graphene oxide with intrinsic hydrogen peroxide catalytic activity for hydrogen peroxide and glucose detection / H. Yang [et al.] // Biosens. Bioelectron. 2013. V. 41. P. 172-179.11. Chen B., Ma M., Su X. An amperometric penicillin biosensor with enhanced sensitivity based on co-immobilization of carbon nanotubes, hematein, and ß-lactamase on glassy carbon electrode // Anal. Chim. Acta. 2010. V. 674. P. 89-95.12. Olivé-Monllau R., Munoz-Pascual F.X., Baldrich E. Characterization and optimization of carbon nanotube electrodes produced by magnetic entrapment: Application to paracetamol detection // Sens. Actuators B. 2013. V. 185. P. 685-693.13. Shahrokhian S., Rastgar S. Electrochemical deposition of gold nanoparticles on carbon nanotube coated glassy carbon electrode for the improved sensing of tinidazole // Electrochim. Acta. 2012. V. 78. P. 422-429.14. Unnikrishnan B., Mani V., Chen S.-M. Highly sensitive amperometric sensor for carbamazepine determination based on electrochemically reduced graphene oxide–single-walled carbon nanotube composite film // Sensors and Actuators B. 2012. V. 173. P. 274-280.15. Electrochemical sensor for toxic ractopamine and clenbuterol based on the enhancement effect of graphene oxide / C. Wu [et al.] // Sensors and Actuators B. 2012. V. 168. P. 178-184.16. Manufacture and evaluation of carbon nanotube modified screen-printed electrodes as electrochemical tools / P. Fanjul-Bolado [et al.] // Talanta. 2007. V. 74. P. 427-43317. Li X., Jiang X. Electrostatic layer-by-layer assembled multilayer films of chitosan and carbon nanotubes // New Carbon Materials. 2010. V. 25, № 3. P. 237-240.18. Горкин В.З. Аминоксидазы и их значение в медицина. М.: Медицина, 1981. 336 с.19. Амперометрический моноаминоксидазный биосенсор для определения некоторых антидепрессантов / Э.П. Медянцева [и др.] // Журн. аналит. химии. 2008. Т. 63, №3. С. 302-307.20. Условия функционирования амперометрического биосенсора на основе моноаминоксидазы / Э.П. Медянцева [и др.] // Учёные записки Каз. гос. ун-та. Естественные науки. 2006. Т. 148, № 2. С. 21-29.21. Данилова Л. А. Анализы крови и мочи. СПб.: Салит-Медкнига, 2003. 128 с.22. Совместное вольтамперометрическое определение дофамина и мочевой кислоты на электроде, модифицированном самоорганизующимся монослоем цистамина с наночастицами золота / Л.Г. Шайдарова [и др.] // Журн. прикладн. химии. 2011. Т. 84, вып. 2. С. 222-228.23. Кушманова О.Д., Ивченко Г.М. Руководство к лабораторным занятиям по биологической химии. М.: Медицина, 1983. 272 с.24. Березов Т.Т., Коровкин Б.Ф. Биологическая химия. М.: Медицина, 1998. 704 с.25. European pharmacopoeia 7.0, European Directorate for the Quality of Medicines HealthCare, 2010, V. 2, P. 231-2232