Search

Copyright of Inventum. Ingenieria, Tecnologia e Investigacion is the property of Corporacion Universitaria Minuto de Dios and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cobalt molybdenum carbide supported on activated carbon was synthesized and the effect of sulfiding in catalytic activity of the glycerol trioleate deoxygenation process (DOX) was evaluated. Prior to glyceryl trioleate deoxygenation reactions, the catalyst was reduced and sulfided with CS2/H2. CoMo/CA carbide was characterized by specific area (B.E.T), X-ray diffraction (DRX), elemental analysis (CHON-S), potentiometric titration with butylamine and X-ray photoelectron spectroscopy (XPS). The surface area of the CoMo/CA carbide and the support were 246 m2/g and 881 m2/g, respectively. The XRD analysis verified the presence of the Co6Mo6C2 and metallic cobalt. XPS showed the presence at the surface of signals assignable to Mod+, Mo4+, Mo6+, Co2+, S2- and SO4 2-. The sulfided CoMo/CA carbide showed higher glyceryl trioleate deoxygenation activity than the no sulfided CoMo/CA carbide. The highest yield was obtained at 310 °C, 900 psi H2 and 2 h of reaction (conversion to 100%) and a higher selectivity to heptadecane (55%) and octadecane (45%), favoring the decarboxylation (HDCX) and decarbonylation (HDCn) than the hydrodeoxygenation (HDO). [ABSTRACT FROM AUTHOR]

Copyright of Innotec is the property of Laboratorio Tecnologico del Uruguay and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cobalt molybdenum carbide supported on activated carbon was synthesized and the effect of sulfiding in catalytic activity of the glycerol trioleate deoxygenation process (DOX) was evaluated. Prior to glyceryl trioleate deoxygenation reactions, the catalyst was reduced and sulfided with CS2/H2. CoMo/CA carbide was characterized by specific area (B.E.T), X-ray diffraction (DRX), elemental analysis (CHON-S), potentiometric titration with butylamine and X-ray photoelectron spectroscopy (XPS). The surface area of the CoMo/CA carbide and the support were 246 m2/g and 881 m2/g, respectively. The XRD analysis verified the presence of the Co6Mo6C2 and metallic cobalt. XPS showed the presence at the surface of signals assignable to Moδ+, Mo4+, Mo6+, Co2+, S2- and ... . The sulfided CoMo/CA carbide showed higher glyceryl trioleate deoxygenation activity than the no sulfided CoMo/CA carbide. The highest yield was obtained at 310 ºC, 900 psi H2 and 2 h of reaction (conversion to 100%) and a higher selectivity to heptadecane (55%) and octadecane (45%), favoring the decarboxylation (HDCX) and decarbonylation (HDCn) than the hydrodeoxygenation (HDO). [ABSTRACT FROM AUTHOR]

Copyright of Investigación e Innovación en Ingenierías is the property of Universidad Simon Bolivar and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Identifying the type and best lignocellulosic biomass pretreatment conditions for bioconversion processes requires structural and compositional changes evaluating after its application. This paper presents a review of the main methods used for pretreatments evaluation in lignocellulosic biomass, with emphasis in those used to improve biogas production. It is concluded that modern procedures that use techniques such as chromatography for quantification are more accurate, but very expensive and laborious, which is why classical methods, such as Weender and Van Soest for the analysis of structural carbohydrates and lignin, continue to be used, and potentiometry and colorimetry results attractive alternatives in other determinations. The qualitative changes of its components, such as relocation and the way in which they interact, is another important aspect when interpreting results obtained by applying pretreatments. [ABSTRACT FROM AUTHOR]

Copyright of Exploratoris: Revista de la Realidad Global is the property of PDHTech, LLC and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nowadays numerous investigations are focused on the search of new materials for the manufacture of sensors of diverse types. These materials change their properties in the presence of different chemical agents. Polyaniline (PANI) and ITO can be used as sensitive materials to detect concentrations of various ions. In this work, glass/ITO/PANI-LS and glass/ITO working electrodes were constructed for the measurement of pH with dimensions of 2.5 cm × 1.5 cm and 2.5 cm × 2.5 cm. The deposition of the PANI-LS layers was performed using the Layer-by-Layer technique. A potentiometric measurement system for pH measurement was designed, based on the use of Virtual Instrumentation techniques. The results showed that the glass/ ITO/ PANI-LS and glass/ ITO electrodes had potentiometric responses close to nernstian in a pH measurement range of 3 to 11 units. In this measurement range there was a linear relationship between the difference in voltage and pH, which is evidenced with coefficients of linear regression and correlation higher than 0.9. The results obtained experimentally are similar to those reported in the literature with other materials. [ABSTRACT FROM AUTHOR]

Different measurement systems for acid-base titrations were evaluated to determine which one had the best metrological characteristics. These systems included volumetric and gravimetric titrations, which were combined with different detection systems: (i) potentiometry, (ii) acid-base indicator, and (iii) electrolytic conductivity. This article proposes a new approach for estimating the measurement uncertainty associated with the detection of the equivalence point. The results showed that, for the determination of the equivalence point, the lowest uncertainties were obtained by the potentiometric method in comparison with the conductometric method, whose bias was 78 times higher. The potentiometric method, however, was strongly dependent on the instrument resolution and/or the titrant amount that is added close to the equivalence point. It was also found that uncertainty decreases about 40% using gravimetric methods as compared to volumetric methods. When performing bias evaluation of the measurement systems according to the ISO 33:2015 guide, results showed that, among the evaluated methods, the gravimetric method with potentiometric detection presented the best metrological characteristics, with the lowest biases and uncertainties. [ABSTRACT FROM AUTHOR]

The partial validation of the potentiometric method was conducted by means of selective electrodes for the nitrate contents quantification in samples of groundwater and wastewaters. First, the performance parameters were evaluated: linearity, sensitivity, limit of detection (LD), limit of quantification (LC), precision and matrix effect. A linear range was obtained from 0,5 to 100 mg/L of nitrate, detection limit of 0,367 mg/L and the quantification of 1,224 mg/L. The coefficient of variation is below two, which is considerably lower at nitrate concentrations above 30 mg/L. A comparison was also made between the established calibration curve and the standard addition method, displaying the matrix effect. The determination of nitrate was performed in samples of drinking water and wastewater, and did not comply with Cuban water and wastewater standards. [ABSTRACT FROM AUTHOR]

Has been prepared a sensitive electrode to the silver cation for that which was used 5-(4- dimethylaminobenzylidene)rhodanine dissolved in dibutylphthalate (DBP) and immobilized in polylvinyl chloride (PVC) on a support of conductive resin. The results show that the electrode presents a lineal answer in the range from 10-2 to 10-6 mol/L with a slope of 69,90 ± 1,73 mV.dec-1 respectively in the range of time that was analyzed. The time of answer of the electrode was determined (25 s) and the selectivity coefficient was calculated for diverse ions. This study has shown for the studied ions (Cu2+, Pb2+ and Cd2+) that the value of KABPot is in the order of 10-3 mol/L, not being strong interferents for the values obtained. [ABSTRACT FROM AUTHOR]

In this paper we report a chloride ion-selective PVC membrane, using bis (2-ethylhexyl) sebacate (DOS) as plasticizer and 2-(5-(4-nitrophenyl)furyl)-4,5-diphenyl imidazole (FFDFIN) as ionosphere. The constructed electrodes showed a fast potentiometric response to chloride in the concentration range from 10-6 to 10-2 mol ⋅ dm-3 with Nernstian slopes. In the case of electrodes prepared containing 1 and 3 wt % of the ionosphere, the lifetime of the sensor was estimated to be about 6-7 days. The lifetime of the sensor containing 7 wt % of ionosphere was about 15-18 days. The electrode containing 7 wt % of ionosphere was applied as an indicator electrode in the potentiometric titration of silver ions with NaCl. [ABSTRACT FROM AUTHOR]

The electronic properties of organic materials can be changed by the influence of different chemical agents. These changes give the possibility to use these materials in different applications like sensors. One of the organic materials studied as detection layer for this kind of sensors is polyaniline (PANI). In this work a Glass/ITO/PANI electrode of 2.5 cm x 1.5 cm x 0.25 cm was constructed using layer by layer (LbL) technique. The potentiometric response was obtained through an instrumentation amplifier (INA116), using a reference electrode (Ag/AgCl) and a work electrode of Glass/ITO/PANI. Buffer solutions with different pH values were evaluated. As results of electrodes characterization, the sensibility of the potentiometric response was -55,12 mV/pH. [ABSTRACT FROM AUTHOR]

Copyright of Comunicaçõe Geológicas is the property of Laboratorio Nacional de Energia e Geologia, I.P. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista ADM is the property of Asociacion Dental Mexicana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Avances en Ciencias e Ingeniería is the property of Avances en Ciencias e Ingenieria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of FABICIB: Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral is the property of Universidad Nacional del Litoral and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Umbral Científico is the property of Universidad Manuela Beltran and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cuantification is the aim of the Analytical Chemistry. Several analytical methods can be used by this. An usual, simple, accurate technique and non-expensive is the potentiometric method. But the halides potentiometric titration have several troubles, because a calomel or silver/silver chloride reference electrode can not be located directly in the titration vessel without serious error from the slight leakage of the chloride ions from the reference electrode, the difficulty is eliminated by immersing the reference electrode in a potassium nitrate solution, that is connected to the analyte solution by a salt bridge. In this paper we suggest to work with a silver-posai electrode, where posai is the reference electrode, but without chloride ions because the posai's potential depend on pH (pH = 4, we work). [ABSTRACT FROM AUTHOR]

This report documents the evaluation results of POSAI-316 electrode used as an alternative to conventional glass-indicator electrode to measure pH in ampiciline's potentiometric micro-titration. The results obtained showed a complete equivalency of POSAI-316 to conventional glass electrode during the titration of ampiciline (in CH3COOH ) with HClO4. [ABSTRACT FROM AUTHOR]

This report documents the evaluation results of POSAI-316 electrode used as an alternative to conventional glass-indicator electrode to measure pH in caffeine's potentiometric micro-titration. The results obtained showed a complete equivalency of POSAI-316 to conventional glass electrode during the titration of caffeine (30, 40 y 50 mg in CH3COOH) with HClO4. [ABSTRACT FROM AUTHOR]

They have been developed analytical techniques to determine an organomercurial bioactive compound that was synthesized from 3-amino-3-methylthio-(5-phenyl-[1,3,4]oxodiazol-2-yl)ethylacrilate, that presents bioactive properties. One of them is based on the potentiometric titration of the additional percloric acid that was added previously. The other technique consists on the complexometric determination of mercury with ammonia thiocyanate. They have been determined some validation parameters that prove that these techniques can be applied to the analytical control of the mentioned product. Besides they have been compared both methods statistically. As a result these techniques don't have significantly differences. [ABSTRACT FROM AUTHOR]

A potentiometric method to determine reducing sugars, avoiding the use of the traditional methylene blue indicator, was developed. A factorial design 2x3 was instrumental to assess the difference between these methods; it showed that there is no significant difference in the equivalence point detection with or without indicator, under the experimental conditions. For the second part, a simple method, tailored to non sophisticated laboratories, was developed to determine water absorption and water solubility indexes for cassava sour starches. The study allowed to identify sources of variation (pouring volume, centrifuge speed and time, and water temperature for starch solubility) that can cause lower reproducibility than expected. The procedure has the potential to become a quality control tool. [ABSTRACT FROM AUTHOR]

It has been developed an anhydrovolumetric technique by potentiometric detection for determination the purity of the 3-amino-3-methylthio-(5-phenyl-[1,3,4]oxodiazol-2-yl-ethylacrilate using percloric acid as titration agent. They have been determined validation parameters such as precision, exactness and selectivity. The referred substance is a raw material in the synthesis of other products which show antimicrobian and antifungic action. [ABSTRACT FROM AUTHOR]

Se presenta un estudio del comportamiento de un electrodo ion-selectivo de bromuro (AgBr) en una solución de iones de bromuro con valores altos de iones de cloruro. Se comparan las variaciones potenciométricas calculadas termodinámicamente con las mediciones experimentales y se describe la reversibilidad potenciométrica de la membrana AgBr según los niveles relativos de iones de cloruro sobre los iones de bromuro.