cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.6857921.v1
title: Protección de acero para instrumentos quirúrgicos con recubrimientos duros en base carbono tipo DLC

description: ABSTRACT Martensitic stainless steels can be used in different applications such as surgical instruments where a good wear and corrosion resistance are required. Surface modification treatments such as nitriding improve the mechanical properties of these steels, however; they affect the corrosion resistance. For this reason, the DLC (Diamond Like Carbon) coatings deposition can be convenient. The wear and corrosion behaviour was studied in duplex samples (nitrided and PACVD coated) and they were compared with nitrided and only coated samples and with those without treatment, only heat treated (quench and tempering). The coatings were analyzed by Raman spectroscopy and EDS. Pin on disk tests were performed and the adhesion was evaluated using Scratch Test and Rockwell C Indentation. The nanohardness was measured with a Berkovich indenter. The corrosion tests for surgical instruments (according to the Standard ASTM F 1089 -02) and Spray Salt Fog tests were carried out. In the DLC coatings, the ID/IG ratio was 0.8 and the hydrogen content was calculated and resulted to be about 20 %. The coating thickness was 2 µm and the hardness reached 24 GPa. The nitrided layer thickness was 10 µm. The duplex and coated samples presented low friction coefficient and the wear volume loss was undetectable. The coatings had good corrosion behaviour in the corrosion tests. Nevertheless, the nitrided sample presented a corroded region in the copper sulfate and boil tests. The duplex samples had better adhesion than the coated samples in scratch test and indentation Rockwell C.
DOI: 10.6084/m9.figshare.6857915
title: Characterization of additives in NR formulations by TLC-IR (UATR)

description: Abstract It is a well-established fact that rubber accelerator is essential to provide solution in different sectors. However, there is a reversal process which can reduce the material performance. Sulfur accelerators donors and organic peroxides have been presented as a solution to the problem. The methodology development that can separate or characterize those components is a challenge and still allows gaps, explained by the application of conventional technique to reach this goal. This study aimed at contributing to the use of off-line coupling of thin layer chromatography (TLC)/infrared spectroscopy (IR) by Universal Attenuated Total Reflection (UATR) for analysis of N-cyclohexyl-2-benzotiazolsulfenamide (CBS), tetraethylthiuram disulfide (TMTD) and dicumyl peroxide (DCP), in natural poly-cis-isoprene (NR) formulations, containing naphthenic oil. The best results were obtained for the plasticizer and DCP, in formulations that had a greater proportion of these compounds. The separation of CBS and TMTD was made with less effectiveness, due to bands overlapping.
DOI: 10.6084/m9.figshare.6857912
title: Rolling contact fatigue of quenched TiN coated SAE 1050 steel

description: ABSTRACT The use of ceramic coatings of the nitride, carbide, or diamond type on steel substrates promotes the improvement of tribology properties. Nevertheless, high hardness gradients and adhesion problems may deteriorate the performance of these coatings when subjected to Rolling Contact Fatigue (RCF). Some studies on steels with ceramic coatings were carried out on steels that sustain hardness at elevated temperature. In the present study, a low cost steel, SAE 1050 was used with a combined surface treatment consisting of a TiN Physical Vapor Deposited (PVD) coating plus a subsequent induction hardening, in order to give the coating high substrate hardness, necessary to withstand the contact stresses. The proposed treatment sequence (different to that usually employed as quenching + PVD), was intended to sustain the high hardness of the quenched steel, even though the consequences on the previous PVD coating are unknown. The tests to evaluate RCF were carried out with a washer type fatigue tester in which a disc sample is rotated under load against a thrust bearing acting as a counterpart. All the system is lubricated by immersion in ISO VG 100 industrial oil. The RCF life values for the individual tests were statistically analyzed and the wear tracks were studied by optical and scanning electron microscopy. Also mappings by X-ray dispersive spectroscopy (EDS) were carried out. The proposed sequence for the surface treatment allowed to obtain some of the typical improvements for coatings as for example those related to low friction, adhesion and abrasion resistance, without impairing the RCF resistance. These benefits are possible even tough plain medium carbon steel was used. X ray diffraction analyses were also carried out in order to evaluate the coating degradation after quenching.
DOI: 10.6084/m9.figshare.6857912.v1
title: Rolling contact fatigue of quenched TiN coated SAE 1050 steel

description: ABSTRACT The use of ceramic coatings of the nitride, carbide, or diamond type on steel substrates promotes the improvement of tribology properties. Nevertheless, high hardness gradients and adhesion problems may deteriorate the performance of these coatings when subjected to Rolling Contact Fatigue (RCF). Some studies on steels with ceramic coatings were carried out on steels that sustain hardness at elevated temperature. In the present study, a low cost steel, SAE 1050 was used with a combined surface treatment consisting of a TiN Physical Vapor Deposited (PVD) coating plus a subsequent induction hardening, in order to give the coating high substrate hardness, necessary to withstand the contact stresses. The proposed treatment sequence (different to that usually employed as quenching + PVD), was intended to sustain the high hardness of the quenched steel, even though the consequences on the previous PVD coating are unknown. The tests to evaluate RCF were carried out with a washer type fatigue tester in which a disc sample is rotated under load against a thrust bearing acting as a counterpart. All the system is lubricated by immersion in ISO VG 100 industrial oil. The RCF life values for the individual tests were statistically analyzed and the wear tracks were studied by optical and scanning electron microscopy. Also mappings by X-ray dispersive spectroscopy (EDS) were carried out. The proposed sequence for the surface treatment allowed to obtain some of the typical improvements for coatings as for example those related to low friction, adhesion and abrasion resistance, without impairing the RCF resistance. These benefits are possible even tough plain medium carbon steel was used. X ray diffraction analyses were also carried out in order to evaluate the coating degradation after quenching.
DOI: 10.6084/m9.figshare.6857915.v1
title: Characterization of additives in NR formulations by TLC-IR (UATR)

description: Abstract It is a well-established fact that rubber accelerator is essential to provide solution in different sectors. However, there is a reversal process which can reduce the material performance. Sulfur accelerators donors and organic peroxides have been presented as a solution to the problem. The methodology development that can separate or characterize those components is a challenge and still allows gaps, explained by the application of conventional technique to reach this goal. This study aimed at contributing to the use of off-line coupling of thin layer chromatography (TLC)/infrared spectroscopy (IR) by Universal Attenuated Total Reflection (UATR) for analysis of N-cyclohexyl-2-benzotiazolsulfenamide (CBS), tetraethylthiuram disulfide (TMTD) and dicumyl peroxide (DCP), in natural poly-cis-isoprene (NR) formulations, containing naphthenic oil. The best results were obtained for the plasticizer and DCP, in formulations that had a greater proportion of these compounds. The separation of CBS and TMTD was made with less effectiveness, due to bands overlapping.
DOI: 10.6084/m9.figshare.6857909
title: Caracterización de daño por “b-value” de eventos de emisión acústica en ensayos de rotura de roca andesita

description: ABSTRACT Acoustic emission is a phenomenon that produces elastic waves when materials are subjected to tension. These waves spread towards the material surface where they are received by sensors that convert them into electrical signals for further analysis. In this work, acoustic emission signals were analysed in order to evaluate the amount of accumulated damage in a material when it is subjected to tensions that make it to fracture. The Gutenberg-Richter law predicts a potential behaviour, given by b-value, between the cumulative number of acoustic emission events and the amplitude of them. Taking account of acoustic emission signals obtained in previous works, in andesite samples subjected to uniaxial compression up to break, an analysis of the progress of b-value was done in order to characterize the material damage occurred. A b-value of b = 1.105 was obtained with a good correlation coefficient of 0.995. The value obtained from the b-value is the expected value that ranges between 0.5 and 1.5. The analysis of the signals allowed to correlate the change of the b-value with the relative maximum values of the acoustic emission parameters.
DOI: 10.6084/m9.figshare.6857903
title: Nafion/sulfonated poly(indene) polyelectrolyte membranes for fuel cell application

description: Abstract Sulfonated poly(indene) (SPInd), with 35% and 45% degree of sulfonation, was blended with Nafion to prepare blended membranes with 10, 15 and 20 wt.% of SPInd. Membranes were evaluated by infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy and X-ray diffraction. Water uptake (WU), ion exchange capacity (IEC) and through-plane proton conductivity were measured. The membranes presented similar thermal stability to Nafion. WU was slightly higher for Nafion/SPInd membranes (19-21% at RT and 40-44% at 90 °C) compared with recast Nafion (16% and 34%, respectively), and IEC values showed a similar trend. Blended Nafion membranes had increased proton conductivity of 2.41 x 10-2 and 2.37 x 10-2 Scm-1 (20 wt. % of SPInd 35% and 45%, respectively), compared with 1.16 x 10-2 Scm-1 for recast Nafion. The results show that the addition of SPInd to Nafion is a potential route towards improving the performance of Nafion in proton conductivity for use in fuel cells devices.
DOI: 10.6084/m9.figshare.6857909.v1
title: Caracterización de daño por “b-value” de eventos de emisión acústica en ensayos de rotura de roca andesita

description: ABSTRACT Acoustic emission is a phenomenon that produces elastic waves when materials are subjected to tension. These waves spread towards the material surface where they are received by sensors that convert them into electrical signals for further analysis. In this work, acoustic emission signals were analysed in order to evaluate the amount of accumulated damage in a material when it is subjected to tensions that make it to fracture. The Gutenberg-Richter law predicts a potential behaviour, given by b-value, between the cumulative number of acoustic emission events and the amplitude of them. Taking account of acoustic emission signals obtained in previous works, in andesite samples subjected to uniaxial compression up to break, an analysis of the progress of b-value was done in order to characterize the material damage occurred. A b-value of b = 1.105 was obtained with a good correlation coefficient of 0.995. The value obtained from the b-value is the expected value that ranges between 0.5 and 1.5. The analysis of the signals allowed to correlate the change of the b-value with the relative maximum values of the acoustic emission parameters.
DOI: 10.6084/m9.figshare.6857903.v1
title: Nafion/sulfonated poly(indene) polyelectrolyte membranes for fuel cell application

description: Abstract Sulfonated poly(indene) (SPInd), with 35% and 45% degree of sulfonation, was blended with Nafion to prepare blended membranes with 10, 15 and 20 wt.% of SPInd. Membranes were evaluated by infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy and X-ray diffraction. Water uptake (WU), ion exchange capacity (IEC) and through-plane proton conductivity were measured. The membranes presented similar thermal stability to Nafion. WU was slightly higher for Nafion/SPInd membranes (19-21% at RT and 40-44% at 90 °C) compared with recast Nafion (16% and 34%, respectively), and IEC values showed a similar trend. Blended Nafion membranes had increased proton conductivity of 2.41 x 10-2 and 2.37 x 10-2 Scm-1 (20 wt. % of SPInd 35% and 45%, respectively), compared with 1.16 x 10-2 Scm-1 for recast Nafion. The results show that the addition of SPInd to Nafion is a potential route towards improving the performance of Nafion in proton conductivity for use in fuel cells devices.
DOI: 10.6084/m9.figshare.6857900
title: Effect of disinfection techniques on physical-mechanical properties of a microwave-activated acrylic resin

description: Abstract The effects of disinfection by microwave irradiation and immersion in peracetic acid on the physical-mechanical properties of a microwave-activated acrylic resin were evaluated. Specimens of acrylic resin were divided into a control group (specimens not disinfected) and 2 test groups subjected to one disinfection method: microwave irradiation at 850 W for 1 minute or immersion in 50 mL of 0.2% peracetic acid for 5 minutes. Specimens were submitted to Knoop hardness, flexural strength, flexural modulus, Izod impact, water sorption and solubility, glass transition temperature, and degree of conversion tests. Microwave disinfection significantly increased the mean Knoop hardness, Izod impact strength, water sorption, water solubility and glass transition temperature, whereas the flexural properties remained unaffected. Microwave disinfection increased the degree of conversion. Peracetic acid disinfection showed no changes in any properties. Both disinfection techniques did not adversely affect the evaluated properties.
DOI: 10.6084/m9.figshare.6857900.v1
title: Effect of disinfection techniques on physical-mechanical properties of a microwave-activated acrylic resin

description: Abstract The effects of disinfection by microwave irradiation and immersion in peracetic acid on the physical-mechanical properties of a microwave-activated acrylic resin were evaluated. Specimens of acrylic resin were divided into a control group (specimens not disinfected) and 2 test groups subjected to one disinfection method: microwave irradiation at 850 W for 1 minute or immersion in 50 mL of 0.2% peracetic acid for 5 minutes. Specimens were submitted to Knoop hardness, flexural strength, flexural modulus, Izod impact, water sorption and solubility, glass transition temperature, and degree of conversion tests. Microwave disinfection significantly increased the mean Knoop hardness, Izod impact strength, water sorption, water solubility and glass transition temperature, whereas the flexural properties remained unaffected. Microwave disinfection increased the degree of conversion. Peracetic acid disinfection showed no changes in any properties. Both disinfection techniques did not adversely affect the evaluated properties.
DOI: 10.6084/m9.figshare.6857888
title: Surface treated bagasse fiber ash on rheological, mechanical properties of PLA/BFA biocomposites

description: Abstract The use of silica based bagasse fiber ash (BFA) as a reinforcing filler in polylactic acid (PLA) biocomposites was examined. The effects of surface-treated BFA on the rheological, swelling behavior, and mechanical properties and water absorption of biocomposites were studied. BFA was treated using a silane coupling agent (Bis-[3-(triethoxysilyl)-propy]-tetrasulfide). Composites with BFA were varied from 5 to 25wt.%. The PLA/BFA composite melts were pseudoplastic non -Newtonion fluid and exhibited a shear thinning behavior. The viscosity of the surface-treated BFA biocomposites was higher than that of the untreated. The viscosity of the composites decreased with increasing BFA content and shear rate. The extrudate swell of the composites increased with increasing shear rate, whereas it decreased with increasing BFA content and die temperature. The extrudate swell tended to be suppressed when surface-treated BFA was used. Silane treated BFA composites showed improvement in their mechanical properties, and exhibited significantly reduced water absorption.
DOI: 10.6084/m9.figshare.6857891
title: Temporal Variability of Solar Radiation During the GOAmazon 2014/15 Experiment

description: Abstract The present work studied the temporal variability of the three components of solar irradiation (global, direct and diffuse) at the Manacapuru region, 66 km distant from Manaus-AM, within the scope of the GOAmazon 2014/15 project, analyzing data for the years of 2014 and 2015. Also it was analyzed the cloud cover data and precipitation. In general, the cloud cover for both years were similar and their typical values are 20-25% (dry season) and 35-40% (wet period). The typical values of global, direct and diffuse solar irradiance were presented for different time scale (hourly and seasonal) as well as variations for the years 2014 and 2015 (interannual scale). The interrelationships amongst the 3 components for hourly and monthly values were presented and it can be noticed that global and direct solar irradiances were directly related although both were inversely correlated with the diffuse solar irradiance. Finally, the ENSO 2015 event was discussed and how it was impacted, the measurements as it had lower cloud cover and rain the higher aerosol concentration.
DOI: 10.6084/m9.figshare.6857888.v1
title: Surface treated bagasse fiber ash on rheological, mechanical properties of PLA/BFA biocomposites

description: Abstract The use of silica based bagasse fiber ash (BFA) as a reinforcing filler in polylactic acid (PLA) biocomposites was examined. The effects of surface-treated BFA on the rheological, swelling behavior, and mechanical properties and water absorption of biocomposites were studied. BFA was treated using a silane coupling agent (Bis-[3-(triethoxysilyl)-propy]-tetrasulfide). Composites with BFA were varied from 5 to 25wt.%. The PLA/BFA composite melts were pseudoplastic non -Newtonion fluid and exhibited a shear thinning behavior. The viscosity of the surface-treated BFA biocomposites was higher than that of the untreated. The viscosity of the composites decreased with increasing BFA content and shear rate. The extrudate swell of the composites increased with increasing shear rate, whereas it decreased with increasing BFA content and die temperature. The extrudate swell tended to be suppressed when surface-treated BFA was used. Silane treated BFA composites showed improvement in their mechanical properties, and exhibited significantly reduced water absorption.
DOI: 10.6084/m9.figshare.6857891.v1
title: Temporal Variability of Solar Radiation During the GOAmazon 2014/15 Experiment

description: Abstract The present work studied the temporal variability of the three components of solar irradiation (global, direct and diffuse) at the Manacapuru region, 66 km distant from Manaus-AM, within the scope of the GOAmazon 2014/15 project, analyzing data for the years of 2014 and 2015. Also it was analyzed the cloud cover data and precipitation. In general, the cloud cover for both years were similar and their typical values are 20-25% (dry season) and 35-40% (wet period). The typical values of global, direct and diffuse solar irradiance were presented for different time scale (hourly and seasonal) as well as variations for the years 2014 and 2015 (interannual scale). The interrelationships amongst the 3 components for hourly and monthly values were presented and it can be noticed that global and direct solar irradiances were directly related although both were inversely correlated with the diffuse solar irradiance. Finally, the ENSO 2015 event was discussed and how it was impacted, the measurements as it had lower cloud cover and rain the higher aerosol concentration.
DOI: 10.6084/m9.figshare.6857885
title: UATR and NIRA evaluation in the quantification of ATBC in NC blends

description: Abstract The paint industry requires rapid and accurate methodologies of raw materials qualitiy controls. For example, the evaluation of the suitable ratio of binary mixtures of polymer/plasticizer such as nitrocellulose (NC)/acetyl tributyl citrate (ATBC) must be done, since this ratio is directly related to the performance of the final product. However, there is a small number of quantitative methodologies of such control in the literature. In this context, in this paper, the applicability of Infrared Fourier Transform Spectroscopy (FT-IR) techniques by using universal total attenuated reflection (UATR), in the middle infrared (MIR), and the reflectance analysis in the near infrared region (NIRA) is evaluated for the quantification of plasticizer ATBC in mixtures with NC. MIR and NIR methodologies presented good results such as: practicality of not requiring refined sample preparation, analysis time about 30 min and good accuracy, suitable data for using in the quality control laboratories of paint industry.
DOI: 10.6084/m9.figshare.6857885.v1
title: UATR and NIRA evaluation in the quantification of ATBC in NC blends

description: Abstract The paint industry requires rapid and accurate methodologies of raw materials qualitiy controls. For example, the evaluation of the suitable ratio of binary mixtures of polymer/plasticizer such as nitrocellulose (NC)/acetyl tributyl citrate (ATBC) must be done, since this ratio is directly related to the performance of the final product. However, there is a small number of quantitative methodologies of such control in the literature. In this context, in this paper, the applicability of Infrared Fourier Transform Spectroscopy (FT-IR) techniques by using universal total attenuated reflection (UATR), in the middle infrared (MIR), and the reflectance analysis in the near infrared region (NIRA) is evaluated for the quantification of plasticizer ATBC in mixtures with NC. MIR and NIR methodologies presented good results such as: practicality of not requiring refined sample preparation, analysis time about 30 min and good accuracy, suitable data for using in the quality control laboratories of paint industry.
DOI: 10.6084/m9.figshare.6857879
title: Chitosan and gum arabic nanoparticles for heavy metal adsorption

description: Abstract Chitosan (CT) is a polysaccharide with the ability to adsorb metals on its surface. In this work, CT-based nanoparticles (NPs) are produced by complex formation with gum arabic (GA) to increase their adsorbent potential for removal of heavy metals in aqueous medium. Adsorption efficiency is evaluated as a function of NP composition and polysaccharide concentration. NPs are sized from 250 to 375 nm at a zeta potential up to -25 mV, suggesting stability to adsorb metals. In particular, CTGA56 and CTGA80 NPs adsorbed a substantially higher amount of copper ions than pure CT. Adsorption kinetics studies showed that the reaction process followed a pseudo second-order model and the adsorption isotherm results fit a Langmuir model, highlighting the monolayer adsorption process with prominent adsorption capacity. These findings indicate the adsorbent potential of CTGA NPs and suggest that these particles can be used for removal of metal ions from contaminated water sources.