cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.8091440
title: TiO2-MEDIATED PHOTOCATALYSIS AT THE NANOPARTICULATE STATE: REVIEW OF THE REACTIVITY BY THE TRAPPING CONCEPT AND SOME APPLICATIONS IN ANALYTICAL CHEMISTRY

description: TiO2 has been used as a white pigment and studied since the first decades of the XX century for the undesirable chalking of outdoor paintings exposed to sunlight. Since the first report of Honda and Fujishima (1972) of the water splitting by the harvesting of sunlight on a n-type single crystal TiO2 electrode, the engagement of researchers with the field has grown steadily. TiO2-photocatalysis has joined the group of advanced oxidation processes for potential new water and wastewater treatments but, despite of its high chemical and photochemical stability and the great oxidizing power of its photogenerated holes, photons in UVA spectral region are needed to accomplish the high band gap, limiting the yield of sun-driven environmental applications. Nevertheless, this shortcoming has not restricted benchtop research and small and medium scale applications also relying on artificial UV sources, especially nowadays that highly-efficient UVA-LEDs are available. Herein, we review the fundamental aspects and the practical attributions of the trapping model in the charge transfer kinetics of photogenerated holes in nanoparticulate TiO2. Regarding to new practical uses, we focus our attention on some ingenious applications of this photocatalyst in the field of analytical chemistry, covering also subjects never reviewed before.
DOI: 10.6084/m9.figshare.8091440.v1
title: TiO2-MEDIATED PHOTOCATALYSIS AT THE NANOPARTICULATE STATE: REVIEW OF THE REACTIVITY BY THE TRAPPING CONCEPT AND SOME APPLICATIONS IN ANALYTICAL CHEMISTRY

description: TiO2 has been used as a white pigment and studied since the first decades of the XX century for the undesirable chalking of outdoor paintings exposed to sunlight. Since the first report of Honda and Fujishima (1972) of the water splitting by the harvesting of sunlight on a n-type single crystal TiO2 electrode, the engagement of researchers with the field has grown steadily. TiO2-photocatalysis has joined the group of advanced oxidation processes for potential new water and wastewater treatments but, despite of its high chemical and photochemical stability and the great oxidizing power of its photogenerated holes, photons in UVA spectral region are needed to accomplish the high band gap, limiting the yield of sun-driven environmental applications. Nevertheless, this shortcoming has not restricted benchtop research and small and medium scale applications also relying on artificial UV sources, especially nowadays that highly-efficient UVA-LEDs are available. Herein, we review the fundamental aspects and the practical attributions of the trapping model in the charge transfer kinetics of photogenerated holes in nanoparticulate TiO2. Regarding to new practical uses, we focus our attention on some ingenious applications of this photocatalyst in the field of analytical chemistry, covering also subjects never reviewed before.
DOI: 10.6084/m9.figshare.8195135
title: PREPARATION AND CHARACTERIZATION OF A QUERCETIN-TETRAETHYL ETHER-BASED PHOTOPROTECTIVE NANOEMULSION

description: Although Quercetin absorbs in the UVA/UVB electromagnetic region, it is limited for applications as a UV filter due to its low lipophilicity and capacity to penetrate the epidermis. In order to overcome this limitation, we synthetized and evaluated the photo protective properties of a derivative obtained from Quercetin. The derivative was prepared by alkylation of Quercetin with iodoethane and characterized by IR and NMR spectroscopy. The in vitro Solar Protection Factor was determined by the Mansur method and the cytotoxicity was evaluated using hepatocellular cell (Hep G2) cells. Finally, Quercetin and the corresponding derivative were incorporated in nanoemulsions. Nanoemulsions with particles sizes between 53 and 73 nm were obtained, and polydispersity indexes were around 0.1, indicating good homogeneity of the nanoemulsion particles. The cell viability study for the Quercetin derivative indicated a very low cytotoxicity profile. The chemical modification of Quercetin resulted in a promising compound with improved properties desirable for skin penetration and incorporation into sunscreen formulations.
DOI: 10.6084/m9.figshare.8195135.v1
title: PREPARATION AND CHARACTERIZATION OF A QUERCETIN-TETRAETHYL ETHER-BASED PHOTOPROTECTIVE NANOEMULSION

description: Although Quercetin absorbs in the UVA/UVB electromagnetic region, it is limited for applications as a UV filter due to its low lipophilicity and capacity to penetrate the epidermis. In order to overcome this limitation, we synthetized and evaluated the photo protective properties of a derivative obtained from Quercetin. The derivative was prepared by alkylation of Quercetin with iodoethane and characterized by IR and NMR spectroscopy. The in vitro Solar Protection Factor was determined by the Mansur method and the cytotoxicity was evaluated using hepatocellular cell (Hep G2) cells. Finally, Quercetin and the corresponding derivative were incorporated in nanoemulsions. Nanoemulsions with particles sizes between 53 and 73 nm were obtained, and polydispersity indexes were around 0.1, indicating good homogeneity of the nanoemulsion particles. The cell viability study for the Quercetin derivative indicated a very low cytotoxicity profile. The chemical modification of Quercetin resulted in a promising compound with improved properties desirable for skin penetration and incorporation into sunscreen formulations.
DOI: 10.6084/m9.figshare.8195249
title: EVALUATION OF COCAINE SAMPLES SEIZED IN THE STREETS OF THE STATE OF RIO DE JANEIRO, BRAZIL

description: Fifty-two samples of street cocaine seized in the state of Rio de Janeiro, from May 2016 to April 2017, were evaluated according to their purity, presence of inorganic and sugar diluents and concentration of pharmacologically active adulterants. Cocaine contents, as well as the adulterants caffeine, lidocaine and phenacetin, were evaluated by gas chromatography coupled with mass spectrometry. The samples were screened by Raman spectroscopy for the presence of inorganic diluents and carbohydrates. The main diluents were calcium carbonate and sodium bicarbonate, which were found in 93% and 71% of the cocaine hydrochloride samples, respectively. Caffeine was found in 91% of the cocaine hydrochloride samples, while phenacetin was found in all freebase cocaine samples. Freebase cocaine samples were majorly composed of pharmacological active compounds (adulterants), unlike cocaine hydrochloride samples, which were majorly composed of inorganic compounds (diluents). It could be observed, by Raman Spectroscopy associated to multivariate analysis, similarities on cocaine hydrochloride composition according to certain criminal gangs. The percentage of pharmacological active compounds varied significantly on the analyzed samples, showing that these adulterants are indiscriminately added to street cocaine, what may increase consumers’ health risks.
DOI: 10.6084/m9.figshare.8195249.v1
title: EVALUATION OF COCAINE SAMPLES SEIZED IN THE STREETS OF THE STATE OF RIO DE JANEIRO, BRAZIL

description: Fifty-two samples of street cocaine seized in the state of Rio de Janeiro, from May 2016 to April 2017, were evaluated according to their purity, presence of inorganic and sugar diluents and concentration of pharmacologically active adulterants. Cocaine contents, as well as the adulterants caffeine, lidocaine and phenacetin, were evaluated by gas chromatography coupled with mass spectrometry. The samples were screened by Raman spectroscopy for the presence of inorganic diluents and carbohydrates. The main diluents were calcium carbonate and sodium bicarbonate, which were found in 93% and 71% of the cocaine hydrochloride samples, respectively. Caffeine was found in 91% of the cocaine hydrochloride samples, while phenacetin was found in all freebase cocaine samples. Freebase cocaine samples were majorly composed of pharmacological active compounds (adulterants), unlike cocaine hydrochloride samples, which were majorly composed of inorganic compounds (diluents). It could be observed, by Raman Spectroscopy associated to multivariate analysis, similarities on cocaine hydrochloride composition according to certain criminal gangs. The percentage of pharmacological active compounds varied significantly on the analyzed samples, showing that these adulterants are indiscriminately added to street cocaine, what may increase consumers’ health risks.
DOI: 10.6084/m9.figshare.8987333.v1
title: IN-SITU MAGNETOMETRY FOR ELECTRODEPOSITED MATERIALS CHACTERIZATION

description: We have recently made studies of electrodeposits of Co onto graphene attached to different substrates, successfully performed via in-situ magnetization measurements. The magnetic analysis of deposits as a function of time lapse, indicate that Co grows with different magnetic characteristics from the beginning to the end of each run, independent of the substrate over which the graphene has been deposited on. In this technical note, we use these results and some obtained in several previous researches developed in our laboratory during the last 20 years, to show that the association of in-situ magnetometry with electrodeposition processes can be a powerful tool to understand the dynamics of the electrochemistry involved, as well as the physics of the magnetic materials fabricated. The Electrochemical Alternating Gradient Force Magnetometer (EC-AGFM) is appropriate for: (i) studying the magnetic properties of the electrodeposits either during deposition or dissolution; (ii) evaluating the electrodeposition dynamics via the sample’s magnetic response; (iii) scrutiny of the electrodeposits as they undergo chemical changes (oxidation, etc.); (iv) studying the deposited materials from the atomic level up to bulk; v) studying the effects of addition of trace amounts of anions in the solution and their impact on the magnetic properties of metal adatoms.
DOI: 10.6084/m9.figshare.8987333
title: IN-SITU MAGNETOMETRY FOR ELECTRODEPOSITED MATERIALS CHACTERIZATION

description: We have recently made studies of electrodeposits of Co onto graphene attached to different substrates, successfully performed via in-situ magnetization measurements. The magnetic analysis of deposits as a function of time lapse, indicate that Co grows with different magnetic characteristics from the beginning to the end of each run, independent of the substrate over which the graphene has been deposited on. In this technical note, we use these results and some obtained in several previous researches developed in our laboratory during the last 20 years, to show that the association of in-situ magnetometry with electrodeposition processes can be a powerful tool to understand the dynamics of the electrochemistry involved, as well as the physics of the magnetic materials fabricated. The Electrochemical Alternating Gradient Force Magnetometer (EC-AGFM) is appropriate for: (i) studying the magnetic properties of the electrodeposits either during deposition or dissolution; (ii) evaluating the electrodeposition dynamics via the sample’s magnetic response; (iii) scrutiny of the electrodeposits as they undergo chemical changes (oxidation, etc.); (iv) studying the deposited materials from the atomic level up to bulk; v) studying the effects of addition of trace amounts of anions in the solution and their impact on the magnetic properties of metal adatoms.
DOI: 10.6084/m9.figshare.8987336.v1
title: THERMOGRAVIMETRIC AND FTIR ANALYZES OF CORN COB PYROLYSIS

description: Charcoal has a large share in the Brazilian market. The production is carried out by pyrolysis of biomass at different temperatures, between 300 and 500 °C. In this study, the corn cob pyrolysis was investigated using thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Samples after pyrolysis were compared with raw biomass to evaluate changes in fuel characteristics. In DTG curves a reduction in the number of degradation peaks in the carbonized material was observed. The FTIR spectra allowed to identify the aromatic ring of the lignin in the charcoals structure, indicating the presence of this compound even in charcoals produced with a temperature of 500 °C. It can be concluded that the temperature of 400 °C was enough to completely degrade the hemicellulose and cellulose of the biomass, resulting the final product (charcoal) less reactive or thermally more resistant than the in natura corn cob.
DOI: 10.6084/m9.figshare.8987336
title: THERMOGRAVIMETRIC AND FTIR ANALYZES OF CORN COB PYROLYSIS

description: Charcoal has a large share in the Brazilian market. The production is carried out by pyrolysis of biomass at different temperatures, between 300 and 500 °C. In this study, the corn cob pyrolysis was investigated using thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Samples after pyrolysis were compared with raw biomass to evaluate changes in fuel characteristics. In DTG curves a reduction in the number of degradation peaks in the carbonized material was observed. The FTIR spectra allowed to identify the aromatic ring of the lignin in the charcoals structure, indicating the presence of this compound even in charcoals produced with a temperature of 500 °C. It can be concluded that the temperature of 400 °C was enough to completely degrade the hemicellulose and cellulose of the biomass, resulting the final product (charcoal) less reactive or thermally more resistant than the in natura corn cob.
DOI: 10.6084/m9.figshare.19945218.v1
title: SYNTHESIS AND THEORETICAL STUDY OF HPW CATALYSTS SUPPORTED ON NIOBIA CALCINATED AT 500 AND 600 ºC

description: Keggin heteropolyacids (HPW) supported on niobia have been considered for both homogeneous and heterogeneous catalysis due to its special features, like the strong Brönsted acidity, low volatility, high activity and high selectivity for various reactions in comparison with mineral acids. Literature reports many different preparation methods for these catalysts through the addition of HPW solutions, in either water or acid, over niobia under stirring. However not much is known about the way how HPW interacts with the support, neither how the temperature influences this interaction. In order to contribute to expand the knowledge on this field we report here a new way of preparing HPW supported catalysts over niobia calcined at 500 and 600 ºC, followed by a theoretical study meant to check the influence of the temperature increase on the adsorption behavior of the catalysts over the support. Our proposed method showed to be an efficient alternative for impregnation of HPW over niobia, while the theoretical results suggest that pseudohexagonal and orthorhombic are the most likely crystalline forms for these catalysts.
DOI: 10.6084/m9.figshare.19945218
title: SYNTHESIS AND THEORETICAL STUDY OF HPW CATALYSTS SUPPORTED ON NIOBIA CALCINATED AT 500 AND 600 ºC

description: Keggin heteropolyacids (HPW) supported on niobia have been considered for both homogeneous and heterogeneous catalysis due to its special features, like the strong Brönsted acidity, low volatility, high activity and high selectivity for various reactions in comparison with mineral acids. Literature reports many different preparation methods for these catalysts through the addition of HPW solutions, in either water or acid, over niobia under stirring. However not much is known about the way how HPW interacts with the support, neither how the temperature influences this interaction. In order to contribute to expand the knowledge on this field we report here a new way of preparing HPW supported catalysts over niobia calcined at 500 and 600 ºC, followed by a theoretical study meant to check the influence of the temperature increase on the adsorption behavior of the catalysts over the support. Our proposed method showed to be an efficient alternative for impregnation of HPW over niobia, while the theoretical results suggest that pseudohexagonal and orthorhombic are the most likely crystalline forms for these catalysts.
DOI: 10.6084/m9.figshare.9696773
title: Analysis of the chemical reactivity of indaziflam herbicide and its metabolites through global and local reactivity descriptors

description: In the present work, the chemical reactivity of indaziflam N-[(1R,2S)-2,3-dihydro-2,6-dimethyl-1H-inden-1 yl]-6-[(1R)-1-16 fluoroethyl]-1,3,5-triazine-2,4-diamine so called indaziflam (IND) and its metabolites: triazine indanone (ITI), indaziflam carboxylic acid (ICA) and fluoroethyldiaminotriazine (FDAT) was analyzed. The calculations were performed at the X/6 311++G(2d,2p) (where X=B3LYP, M06, M06L and wB97XD) level of theory, in the aqueous phase. The results indicate that ITI is the more reactive followed by ICA, IND and FDAT. The distribution of the active sites was determined evaluating the Fukui function employing the frozen core and finite difference approximations. For electrophilic attacks, IND shows the more reactive zone on the benzene ring, ITI and ICA on the nitrogen atom in the central section and FDAT on its nitrogen atoms. The more nucleophilic sites for IND are observed on the carbon atoms of triazine, on the carbonyl group for ITI, on the carboxylic group for ICA, and on the nitrogen atoms of triazine for FDAT. For free radical attacks case, the more reactive sites for IND are on the benzene and triazine rings, on the carbonyl group, nitrogen of the central section, and nitrogen atoms of triazine, for ITI, carboxylic group for ICA, and on the nitrogen atoms of triazine ring for FDAT.
DOI: 10.6084/m9.figshare.9696773.v1
title: Analysis of the chemical reactivity of indaziflam herbicide and its metabolites through global and local reactivity descriptors

description: In the present work, the chemical reactivity of indaziflam N-[(1R,2S)-2,3-dihydro-2,6-dimethyl-1H-inden-1 yl]-6-[(1R)-1-16 fluoroethyl]-1,3,5-triazine-2,4-diamine so called indaziflam (IND) and its metabolites: triazine indanone (ITI), indaziflam carboxylic acid (ICA) and fluoroethyldiaminotriazine (FDAT) was analyzed. The calculations were performed at the X/6 311++G(2d,2p) (where X=B3LYP, M06, M06L and wB97XD) level of theory, in the aqueous phase. The results indicate that ITI is the more reactive followed by ICA, IND and FDAT. The distribution of the active sites was determined evaluating the Fukui function employing the frozen core and finite difference approximations. For electrophilic attacks, IND shows the more reactive zone on the benzene ring, ITI and ICA on the nitrogen atom in the central section and FDAT on its nitrogen atoms. The more nucleophilic sites for IND are observed on the carbon atoms of triazine, on the carbonyl group for ITI, on the carboxylic group for ICA, and on the nitrogen atoms of triazine for FDAT. For free radical attacks case, the more reactive sites for IND are on the benzene and triazine rings, on the carbonyl group, nitrogen of the central section, and nitrogen atoms of triazine, for ITI, carboxylic group for ICA, and on the nitrogen atoms of triazine ring for FDAT.
DOI: 10.6084/m9.figshare.19945219
title: SYNTHESIS OF MESOPOROUS γ-ALUMINA AND ITS CATALYTIC PERFORMANCE IN DICHLOROPROPANOL CYCLIZATION

description: This paper discusses the synthesis and resulting catalytic performance of mesoporous alumina using aluminum isopropoxide as the aluminum source, and synthesized organosiloxane KH560-540 as template. The effects of the hydrothermal conditions, as well as the amount of templating agent at pH values of 5-9 on the structure of the synthesized mesoporous alumina were investigated by nitrogen adsorption-desorption methods, XRD and electron microscopy. Alumina from a rod-like scaffold structure was obtained, and the specific surface area was as high as 508 m2 g-1. Also, the coordination state of aluminum before and after calcination was analyzed by 27Al-NMR spectroscopy. The role of the templating agent in the synthesis process was determined. The synthesis mechanism of mesoporous alumina prepared by a KH560-540 template was also proposed. The acidity of samples that were synthesized by different templating agents were compared to NH3-TPD, and the content of Si in each sample was tested by ICP-OES, the results show that the silicon content has little effect on the acidity of the sample. Finally, we used the synthesized mesoporous alumina to catalyze the cyclization of dichloropropanol to epichlorohydrin, which showed excellent catalytic performance:dichlorohydrin conversion is up to 96% and epichlorohydrin yield of nearly 92%.
DOI: 10.6084/m9.figshare.19945219.v1
title: SYNTHESIS OF MESOPOROUS γ-ALUMINA AND ITS CATALYTIC PERFORMANCE IN DICHLOROPROPANOL CYCLIZATION

description: This paper discusses the synthesis and resulting catalytic performance of mesoporous alumina using aluminum isopropoxide as the aluminum source, and synthesized organosiloxane KH560-540 as template. The effects of the hydrothermal conditions, as well as the amount of templating agent at pH values of 5-9 on the structure of the synthesized mesoporous alumina were investigated by nitrogen adsorption-desorption methods, XRD and electron microscopy. Alumina from a rod-like scaffold structure was obtained, and the specific surface area was as high as 508 m2 g-1. Also, the coordination state of aluminum before and after calcination was analyzed by 27Al-NMR spectroscopy. The role of the templating agent in the synthesis process was determined. The synthesis mechanism of mesoporous alumina prepared by a KH560-540 template was also proposed. The acidity of samples that were synthesized by different templating agents were compared to NH3-TPD, and the content of Si in each sample was tested by ICP-OES, the results show that the silicon content has little effect on the acidity of the sample. Finally, we used the synthesized mesoporous alumina to catalyze the cyclization of dichloropropanol to epichlorohydrin, which showed excellent catalytic performance:dichlorohydrin conversion is up to 96% and epichlorohydrin yield of nearly 92%.
DOI: 10.6084/m9.figshare.10026311
title: HDL-PARTICLES SEPARATION EMPLOYING DIFFERENT PRECIPITATING AGENTS: FUNCTIONAL PROPERTIES OF THE IMPACT OF CHEMICAL PRECIPITATION ON LIPOPROTEIN PARTICLE-SIZE AND PARAOXONASE-1-ACTIVITY

description: First-generation methods used to quantify HDL-cholesterol have been used for decades. Therefore, first-generation precipitatingreagents still in use, the chemical impact on HDL-particles functionality (structure/activity-relationship) is not well-documented. The study aim was to identify the most efficient precipitating-reagent for lipoprotein separation to be used in the HDL functionalevaluation. A cross-sectional design with convenience sampling was conducted. Plasma samples from 40 individuals, both genders, were evaluated. Biochemical analysis was performed after using different chemical precipitants (e.g. polyethylene glycol - PEG (P1), phosphotungstic-acid (P2), and dextran-sulfate/MgCl2 (P3)) to evaluate HDL-particle-size and PON1-activity. Parametric and non-parametric tests were performed using GraphPad-Prism 5.01 (USA). Differences were considered significant when a p-value &lt; 0.05 were obtained. The PON1-activity comparison differed after NaCl stimulation (p &lt; 0.001, paired t-test) and among chemical precipitant treatments. The PON1-activity differed after sample precipitation with P1 when compared to P2, and P3 (p &lt; 0.05; ANOVA), before and after stratification for dyslipidemia group. The HDL particle-size comparison did not differ, but on the other hand, polydispersity differed after sample precipitation with P3 when compared to P1 or P2 (p &lt; 0.05; ANOVA). Dextran- Sulfate/MgCl2 was a better chemical precipitant for PON1-activity, and PEG for HDL-particle-size, respectively. The HDL functional