scholarly journals CARACTERIZAÇÃO ESTRUTURAL DO COMPÓSITO PANI-MAGNETITA COM POTENCIAL APLICABILIDADE EM SENSOR ELETROQUÍMICO

Química Nova ◽  
2021 ◽  
Author(s):  
Caroline Zanotto ◽  
Patrícia Marques ◽  
Eryza Castro
Keyword(s):  
Synthetic Route ◽  
Waste Generation ◽  
New Materials ◽  
Electrochemical Tests ◽  
A Value ◽  
Potential Applicability ◽  
Oxide Particles ◽  
Stable Material

STRUCTURAL CHARACTERIZATION OF THE PANI-MAGNETITE COMPOSITE WITH POTENTIAL APPLICABILITY IN ELECTROCHEMICAL SESNOR. This study presents the production of a composite formed between polyaniline and magnetite (Pani-Mag) through an easy and more economical synthetic route, which satisfactorily contemplates the principles of green chemistry. The production of new materials for technological application also needs to be focused on less waste generation, and greater sustainability. FTIR and DRX analyzes confirm that the interactions between the polymeric phases and the oxide particles occurred in a synergistic way. Saturation magnetization has a value of 33.5 emu g-1, being compatible with reference values in the literature for Pani-Mag composites. The electrochemical tests indicate an electrochemically stable material with the potential to be applied as an electrochemical sensor in the determination of ascorbic acid in solution.

scholarly journals Corrosion of Biocompatible Mg66+xZn30-xCa4 (x=0.2) Bulk Metallic Glasses

2016 ◽  
Vol 61 (2) ◽  
pp. 807-810 ◽  
Author(s):  
R. Nowosielski ◽  
K. Cesarz-Andraczke ◽  
P. Sakiewicz ◽  
A. Maciej ◽  
A. Jakóbik-Kolon ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
X Ray Diffraction ◽  
Electrochemical Tests ◽  
Simulated Environment ◽  
Corrosion Studies ◽  
Physiological Fluid

Abstract The aim of this paper was to investigate the corrosion resistance of Mg66Zn30Ca4 and Mg68Zn28Ca4 metallic glasses and evaluate the ability of this amorphous alloy use for medical applications as biodegradable medical implants. Taking into account the amount of Mg, Zn, Ca elements dissolved in multielectrolyte physiological fluid (MPF) from Mg66+xZn30-xCa4 (x=0.2) alloys the daily dose of evolved ions from alloys components was determined. Additional goal of the paper was determination of corrosion rate (Vcorr) and amount of hydrogen evolved from amorphous magnesium alloys in simulated environment of human body fluids during 24h immersion and during electrochemical tests. Corrosion studies were done in the multielectrolyte physiological fluid (MPF) at 37°C. The amount of hydrogen evolved [ml/cm2] and corrosion rate Vcorr [mm/year] of amorphous Mg66Zn30Ca4 and Mg68Zn28Ca4 alloys were compared. The work also presents characterization of Mg-based bulk metallic glasses structure in the form of 2 mm thickness plates. Samples structure was analyzed by means of X-ray diffraction. Fracture and surface morphology of magnesium alloy samples were identified using scanning electron microscopy.

scholarly journals Use of Dispersive Liquid-Liquid Microextraction and UV-Vis Spectrophotometry for the Determination of Cadmium in Water Samples

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
J. Pérez-Outeiral ◽  
E. Millán ◽  
R. Garcia-Arrona
Keyword(s):  
Water Samples ◽  
Limit Of Detection ◽  
Experimental Conditions ◽  
Cadmium Determination ◽  
A Value ◽  
Relative Standard ◽  
Potential Applicability ◽  
Dispersive Liquid Liquid Microextraction ◽  
Liquid Microextraction

A simple and inexpensive method for cadmium determination in water using dispersive liquid-liquid microextraction and ultraviolet-visible spectrophotometry was developed. In order to obtain the best experimental conditions, experimental design was applied. Calibration was made in the range of 10–100 μg/L, obtaining good linearity (R2 = 0.9947). The obtained limit of detection based on calibration curve was 8.5 μg/L. Intra- and interday repeatability were checked at two levels, obtaining relative standard deviation values from 9.0 to 13.3%. The enrichment factor had a value of 73. Metal interferences were also checked and tolerable limits were evaluated. Finally, the method was applied to cadmium determination in real spiked water samples. Therefore, the method showed potential applicability for cadmium determination in highly contaminated liquid samples.

scholarly journals Electrochemical Characterization of Gelatine Derived Ceramics

2014 ◽  
Vol 14 (4) ◽  
pp. 75-81 ◽  
Author(s):  
A.P. Nowak ◽  
K. Trzciński ◽  
A. Lisowska-Oleksiak
Keyword(s):  
Raman Spectroscopy ◽  
Cyclic Voltammetry ◽  
Cluster Size ◽  
Weight Ratio ◽  
Electrochemical Characterization ◽  
New Materials ◽  
Capacity Fading ◽  
Cyclic Polarization ◽  
Electrochemical Tests

Abstract New materials obtained by pyrolysis of gelatine (G) and poly(1,2-dimethylsilazane) (PSN) (weight ratio: G/PSN 70/30) at temperatures 700 and 900 °C were characterized by SEM and Raman spectroscopy. The presence of ceramics influences on the cluster size of the materials. Electrochemical tests were performed by cyclic voltammetry and galvanostatic cyclic polarization. The capacity of G/PSN was 464 and 527 mAh/g for materials pyrolysed at 700 and 900 °C. The capacity fading was 1 % after 17th cycle for G/PSN at 900 °C. This value is higher of 185 mAh/g in comparison to capacity of gelatine pyrolysed at the same conditions.

DESIGN AND VIBRATIONS IN THE ROTARY HAMMER

10.6036/10297 ◽  
2021 ◽  
Vol DYNA-ACELERADO (0) ◽  
pp. [ 5 pp]-[ 5 pp]
Author(s):  
BEATRIZ IVORRA ZARAGOZA ◽  
SILVIA NUERE MENÉNDEZ-PIDAL ◽  
SARA GOMEZ MARTIN ◽  
JUAN DAVID CANO MORENO ◽  
MIGUEL BERZAL RUBIO
Keyword(s):  
Occupational Diseases ◽  
Construction Sector ◽  
New Materials ◽  
Pneumatic Hammer ◽  
Vibration Syndrome ◽  
A Value ◽  
Materials Used ◽  
Damping Of Vibrations ◽  
Better Than

The vibrations generated by manual machines can cause occupational diseases with both vascular and osteoarticular affectations, also known as hand-arm vibration syndrome. The pneumatic rotary hammer is one of these machines, widely used in the construction sector. In the bibliography consulted, it is found that the transmission of vibrations from the handle to the hand-arm system depends on both the composition of the material and the design of the handle. Although there are already improvements in this damping of vibrations received through the handles, there is a great field for its optimization, redesign and the search for new materials not yet used in the handles of pneumatic hammers. This article presents a methodology for the study of new materials used in the grip, including the analysis of the design, real tests for the characterization of the materials and their simulation by finite elements. The results obtained show that the design is a decisive factor for both vibration damping and weight. The redesigned grip that generates more damping at 33 seconds with a weight of 0.51kg is the "R1" with a value of 0.6346% better than the original grip, "Segeda original", with a weight of 0.55kg and with a damping value of 0.605%. Keywords: industrial design, pneumatic hammer, handle, elastomers, vibrations

Chemical Synthesis and Characterization of Carbon Supported Palladium Electro-Catalysts

2017 ◽  
Vol 16 (05n06) ◽  
pp. 1750007
Author(s):  
J. J. Acosta ◽  
P. C. Favilla ◽  
J. R. Collet-Lacoste
Keyword(s):  
Structure Type ◽  
X Ray Diffraction ◽  
Initial Concentration ◽  
Type Formula ◽  
A Value ◽  
Transmission Electron ◽  
Initial Ph ◽  
Modified Polyol Method

The aim of this work is to present the results obtained for the synthesis of Pd NPs by the modified-polyol method with Vulcan XC-72R as support. Two different ways were used to synthesize catalysts: (a) Maintaining the initial pH of the synthesis equal to 12 and changing the initial concentration of the precursor to obtain an overall 10 wt.% nominal Pd load; (b) Fixing the initial concentration of the precursor at 2[Formula: see text]mM whilst changing the initial pH of the synthesis at different values to obtain an overall 10[Formula: see text]wt.% nominal Pd load. Catalysts were characterized using X-ray diffraction (XRD), Transmission electron microscopy (HRTEM, TEM, STEM) and cyclic voltammetry (CV). This work shows that the density of NPs generated during the nucleation process is a consequence of the fluctuation of the concentration. The standard deviation of the diameters varied linearly with the mean volume for values between 0.5[Formula: see text]mM and 6[Formula: see text]mM, demonstrating that there was a clear separation between nucleation and growth processes. The final mean diameter strongly depends on the initial pH of the synthesis for the same initial concentration of the precursor; mean diameters are smaller for basic media. The analysis of the voltammograms allowed the determination of the coverage fraction of oxygen on Pd, obtaining a value of 0.51 with a structure type [Formula: see text]. The coverage value found for CO is 0.71 with a structure type [Formula: see text]CO.

scholarly journals Effect of Cassava (Manihot esculenta Crantz: Euphorbiaceae) Starch on the Stabilization of Malagasy Lateritic Soil

2020 ◽  
Vol 2 (4) ◽  
pp. 467-481
Author(s):  
Harinivo Olsynthique Razanajatovo ◽  
Serge Ravelomanantsoa ◽  
Elise Octavie Rasoazanany ◽  
Aristote Matondo ◽  
Colette Masengo Ashande ◽  
...  
Keyword(s):  
Building Materials ◽  
Soil Stabilization ◽  
Raw Materials ◽  
Cassava Starch ◽  
Lateritic Soil ◽  
Manihot Esculenta Crantz ◽  
A Value ◽  
Physico Chemical

Laterite is one of the most widespread raw materials, especially in Madagascar. Its valorization as a building material would help to solve many socio-economic problems in Madagascar as well as in Africa. The use of this type of material fits well within the framework of high environmental quality, since the process uses an abundant material that does not require too much energy for its manufacture because it is dried in the open air. The aim of this work was to stabilize the laterite with cassava starch. The valorization of the latter would contribute to the development of new building materials. The study focuses on the mechanical characterization of specimens made with Vontovorona laterite in different proportions, which goes hand in hand with the determination of the physico-chemical parameters of the starch. To make specimens, we used techniques such as extraction, sieving, heating, laterite-stabilizing dosage, mixing, rotting, moulding, clamping, demoulding, drying. The results obtained show that the best stabilizing material is obtained if 15% of starch is mix to lateritic soil. The compressive strength in the dry state of the test specimens (samples) gave a significantly interesting result with a value of 54.8 bars (85% laterite with 15% starch). Thus the use of starch as a stabilizer in construction gave satisfactory results. This eco-friendly process, simple in its steps and practice, should be popularized among artisanal brick makers. Thus, replacing proportions of the Portland cement in soil stabilization with Cassava starch will reduce the overall environmental impact of the stabilization process. 

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

Characterization of Impressed Current Technique to Model Corrosion of Reinforcement in Concrete

2020 ◽  
Vol 11 (1) ◽  
pp. 93-99
Author(s):  
Abu Zakir Morshed ◽  
Sheikh Shakib ◽  
Tanzim Jahin
Keyword(s):  
Immersion Time ◽  
Chloride Content ◽  
Engineering Science ◽  
Coastal Regions ◽  
Faraday’S Law ◽  
Current Technique ◽  
Corrosion Cell ◽  
Impressed Current

Corrosion of reinforcement is an important durability concern for the structures exposed to coastal regions. Since corrosion of reinforcement involves long periods of time, impressed current technique is usually used to accelerate the corrosion of reinforcement in laboratories. Characterization of impressed current technique was the main focus of this research,which involved determination of optimum chloride content and minimum immersion time of specimens for which the application of Faraday’s law could be efficient. To obtain optimum chloride content, the electrolytes in the corrosion cell were prepared similar to that of concrete pore solutions. Concrete prisms of 200 mm by 200 mm by 300 mm were used to determine the minimum immersion time for saturation. It was found that the optimum chloride content was 35 gm/L and the minimum immersion time for saturation was 140 hours. Accounting the results, a modified expression based on Faraday’s law was proposed to calculate weight loss due to corrosion. Journal of Engineering Science 11(1), 2020, 93-99

The Determination of Sense via Deleuze and Blanchot: Paradoxes of the Habitual, the Immemorial, and the Eternal Return

2008 ◽  
Vol 2 (2) ◽  
pp. 155-177 ◽  
Author(s):  
Eugene Brently Young
Keyword(s):  
Eternal Return

Eternal return is the paradox that accounts for the interplay between difference and repetition, a dynamic at the heart of Deleuze's philosophy, and Blanchot's approach to this paradox, even and especially through what it elides, further illuminates it. Deleuze draws on Blanchot's characterisations of difference, forgetting, and the unlivable to depict the ‘sense’ produced via eternal return, which, for Blanchot, is where repetition implicates or ‘carries’ pure difference. However, for Deleuze, difference and the unlivable are also developed by the living repetition or ‘contraction’ of habit, which results in his distinctive characterization of ‘force’, ‘levity’, and sense in eternal return.

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