cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.11997636.v1
title: CANNABINOIDS QUANTIFICATION IN MEDICINAL Cannabis EXTRACTS BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

description: Cannabidiol (CBD) and tetrahydrocannabinol (THC) are the main active principles in the Cannabis extracts. Rich-CBD extracts are indicated to control seizures in epileptic patients, THC is indicated as antiemetic to patients in chemotherapy treatment and extracts with THC and CBD in proportions of approximately 1:1 are indicated to control spasticity in patients with multiple sclerosis. In Brazil epileptic pediatric patients are treated with imported Cannabis extracts registered as food supplement and with national not regulated Cannabis extracts. With the medical Cannabis sanitary regulation in Brazil, quality control methods will be required. A High Performance Liquid Chromatography (HPLC) method was developed and validated for five cannabinoids quantification in oily extracts and resins. The method was applied to 101 Cannabis extracts consumed by patients attended by a risk assessment program. Linearity, selectivity and precision met the validation criteria of national and international sanitary agencies. Cannabis imported oily extracts showed high CBD levels (72.53±60.63 mg mL-1) and low THC levels (1.21±1.32 mg mL-1), while national Cannabis extracts showed mainly two profiles, first composed by negative or cannabinoids traces and the second composed by THC rich extracts (9.81±13.49 mg mL-1). The HPLC method is useful to pharmaceutical production and risk assessment purposes.
DOI: 10.6084/m9.figshare.11997528
title: PRACTICAL ASPECTS OF THE ANALYSIS OF THE PROGRESSION CURVES OF FIRST AND PSEUDO-FIRST ORDER REACTIONS

description: The paper presents a simple method of determining iteratively the progression curve asymptote for first and pseudo-first order reactions. For selected student exercises, thus obtained results were compared (see Supplementary Material) with those found by means of the method of determining asymptotes experimentally. A nonlinear fitting method was additionally employed to assess the accuracy.
DOI: 10.6084/m9.figshare.11997528.v1
title: PRACTICAL ASPECTS OF THE ANALYSIS OF THE PROGRESSION CURVES OF FIRST AND PSEUDO-FIRST ORDER REACTIONS

description: The paper presents a simple method of determining iteratively the progression curve asymptote for first and pseudo-first order reactions. For selected student exercises, thus obtained results were compared (see Supplementary Material) with those found by means of the method of determining asymptotes experimentally. A nonlinear fitting method was additionally employed to assess the accuracy.
DOI: 10.6084/m9.figshare.11997765
title: INTERMOLECULAR INTERACTIONS AND THE SOLUBILITY PHENOMENON: EXPLANATIONS OF CHEMISTRY STUDENTS

description: The present study investigated the use of intermolecular interaction concepts by freshman chemistry students during general chemistry classes, explaining some of the solubility phenomenon. For this purpose, classes on the topic in question were monitored and two tests were asking for explanations for the difference in solubility of oxygen and carbon dioxide in water and in perfluorocarbons and oxygen in fresh or salt water. Students also made graphic representations showing the water - oxygen molecules interactions. An analysis of the data demonstrated that several students had difficulties in correctly identifying that intermolecular interactions are involved in these systems. The concept of polarizability, fundamental in these systems, was rarely used in their explanations. The answers also indicated extensive use of the “like dissolves like” rule to explain solubility rather than using a complete description of the interactive processes involved. Most of the students’ explanations suggest an understanding of the knowledge as data or fact reproducing information and ideas without an effective use and understanding of the chemical concepts.
DOI: 10.6084/m9.figshare.11997765.v1
title: INTERMOLECULAR INTERACTIONS AND THE SOLUBILITY PHENOMENON: EXPLANATIONS OF CHEMISTRY STUDENTS

description: The present study investigated the use of intermolecular interaction concepts by freshman chemistry students during general chemistry classes, explaining some of the solubility phenomenon. For this purpose, classes on the topic in question were monitored and two tests were asking for explanations for the difference in solubility of oxygen and carbon dioxide in water and in perfluorocarbons and oxygen in fresh or salt water. Students also made graphic representations showing the water - oxygen molecules interactions. An analysis of the data demonstrated that several students had difficulties in correctly identifying that intermolecular interactions are involved in these systems. The concept of polarizability, fundamental in these systems, was rarely used in their explanations. The answers also indicated extensive use of the “like dissolves like” rule to explain solubility rather than using a complete description of the interactive processes involved. Most of the students’ explanations suggest an understanding of the knowledge as data or fact reproducing information and ideas without an effective use and understanding of the chemical concepts.
DOI: 10.6084/m9.figshare.11997501
title: USE OF THE DENSITY FUNCTIONAL THEORY IN SPIN CROSSOVER ANALYSIS IN INORGANIC CHEMISTRY CLASSES

description: Spin crossover is a property found in some coordination compounds formed by the first series of transition metals with d4-d7 configuration. These complexes, when stimulated by an external factor (temperature, light, etc.), can be converted from their low spin states to high spin states, or vice versa. However, this issue is not addressed in the Inorganic Chemistry literature used in undergraduate courses. In this work, the Density Functional Theory is used to predict which complexes may present the Spin Cross Over property. In addition to establish a methodology to predict in which situations this process will occur, this computational tool can also be used in undergraduate or postgraduate classes to explore this property in the study of coordination compounds.
DOI: 10.6084/m9.figshare.11997501.v1
title: USE OF THE DENSITY FUNCTIONAL THEORY IN SPIN CROSSOVER ANALYSIS IN INORGANIC CHEMISTRY CLASSES

description: Spin crossover is a property found in some coordination compounds formed by the first series of transition metals with d4-d7 configuration. These complexes, when stimulated by an external factor (temperature, light, etc.), can be converted from their low spin states to high spin states, or vice versa. However, this issue is not addressed in the Inorganic Chemistry literature used in undergraduate courses. In this work, the Density Functional Theory is used to predict which complexes may present the Spin Cross Over property. In addition to establish a methodology to predict in which situations this process will occur, this computational tool can also be used in undergraduate or postgraduate classes to explore this property in the study of coordination compounds.
DOI: 10.6084/m9.figshare.11997639
title: A SET OF ELECTRONIC SHEETS FOR THE IDENTIFICATION AND QUANTIFICATION OF CONSTITUENTS OF ESSENTIAL OILS

description: The identification of essential oils constituents has been made easier and faster by the use of automatic software search engines that compare the experimental mass spectra and calculate the retention indices with those in commercial databases. However, these search engines and databases are very expensive. Electronic sheets have been assembled in a set of linked sheets, so that after some data is inserted, linear retention indices, relative response factors, normalization, area correction and absolute quantitation are calculated automatically. The set has been applied to the analysis of essential oils and volatiles in laboratory routine and substantial reduction in time-consuming and error-prone repetitive work were observed. One specific example for the analysis of an essential oil is provided. The designed electronic sheets can be a costless alternative to commercial software for data handling and identification.
DOI: 10.6084/m9.figshare.11997639.v1
title: A SET OF ELECTRONIC SHEETS FOR THE IDENTIFICATION AND QUANTIFICATION OF CONSTITUENTS OF ESSENTIAL OILS

description: The identification of essential oils constituents has been made easier and faster by the use of automatic software search engines that compare the experimental mass spectra and calculate the retention indices with those in commercial databases. However, these search engines and databases are very expensive. Electronic sheets have been assembled in a set of linked sheets, so that after some data is inserted, linear retention indices, relative response factors, normalization, area correction and absolute quantitation are calculated automatically. The set has been applied to the analysis of essential oils and volatiles in laboratory routine and substantial reduction in time-consuming and error-prone repetitive work were observed. One specific example for the analysis of an essential oil is provided. The designed electronic sheets can be a costless alternative to commercial software for data handling and identification.
DOI: 10.6084/m9.figshare.14278786
title: Non-neoplastic intracranial cystic lesions: not everything is an arachnoid cyst

description: Abstract Intracranial cystic lesions are common findings on neuroimaging examinations, arachnoid cysts being the most common type of such lesions. However, various lesions of congenital, infectious, or vascular origin can present with cysts. In this pictorial essay, we illustrate the main causes of non-neoplastic intracranial cystic lesions, discussing their possible differential diagnoses as well as their most relevant imaging aspects.
DOI: 10.6084/m9.figshare.14278787
title: PHOTOELECTROCATALYTIC CONVERSION OF CO2 AND BIOGAS INTO PRODUCTS OF ENERGY INTEREST USING Ti/TiO2 NANOSTRUCTURED SEMICONDUCTORS MODIFIED WITH COPPER

description: This work describes the superficial modification of Ti/TiO2 nanotubes by copper oxide electrochemical deposition, in different temperatures (25 and 65 ºC), and its application on the photoelectrocatalytic conversion of CO2 and biogas in products of energy interest. The different temperatures deposition resulted in the formation of different geometric forms on the surface of Ti/TiO2 nanotubes and in different photoelectrocatalytic activities. The photoelectrocatalytic conversion in 0.1 mol L-1 Na2SO4 with application of -0.1 V and UV irradiation resulted in the formation of acetone and methanol from CO2 and acetone and ethanol from biogas, being that the acetone production was higher for the semiconductor synthesized at 65 ºC, while the methanol and ethanol production was higher for the semiconductor at 25 ºC. The different characteristics observed, as well as the preferential formation of different products of photoelectrocatalytic reactions for semiconductors synthesized with different electrochemical deposition temperatures are discussed.
DOI: 10.6084/m9.figshare.14278786.v1
title: Non-neoplastic intracranial cystic lesions: not everything is an arachnoid cyst

description: Abstract Intracranial cystic lesions are common findings on neuroimaging examinations, arachnoid cysts being the most common type of such lesions. However, various lesions of congenital, infectious, or vascular origin can present with cysts. In this pictorial essay, we illustrate the main causes of non-neoplastic intracranial cystic lesions, discussing their possible differential diagnoses as well as their most relevant imaging aspects.
DOI: 10.6084/m9.figshare.14278787.v1
title: PHOTOELECTROCATALYTIC CONVERSION OF CO2 AND BIOGAS INTO PRODUCTS OF ENERGY INTEREST USING Ti/TiO2 NANOSTRUCTURED SEMICONDUCTORS MODIFIED WITH COPPER

description: This work describes the superficial modification of Ti/TiO2 nanotubes by copper oxide electrochemical deposition, in different temperatures (25 and 65 ºC), and its application on the photoelectrocatalytic conversion of CO2 and biogas in products of energy interest. The different temperatures deposition resulted in the formation of different geometric forms on the surface of Ti/TiO2 nanotubes and in different photoelectrocatalytic activities. The photoelectrocatalytic conversion in 0.1 mol L-1 Na2SO4 with application of -0.1 V and UV irradiation resulted in the formation of acetone and methanol from CO2 and acetone and ethanol from biogas, being that the acetone production was higher for the semiconductor synthesized at 65 ºC, while the methanol and ethanol production was higher for the semiconductor at 25 ºC. The different characteristics observed, as well as the preferential formation of different products of photoelectrocatalytic reactions for semiconductors synthesized with different electrochemical deposition temperatures are discussed.
DOI: 10.6084/m9.figshare.14278788
title: OPTIMIZATION AND VALIDATION OF QuEChERS BASED METHOD FOR DETERMINATION OF PRESERVATIVES IN COSMETICS BY HPLC-DAD

description: Parabens are widely used as preservatives in the last decades. Others preservatives such as 2-phenoxyethanol, which in addition to his good antimicrobial activity, has low allergenic potential as well others properties of interest to the cosmetic industry. In this work was developed a method for determination of methylparaben (MP), propylparaben (PP) and 2-phenoxyethanol (FE) in cosmetic products by HPLC-DAD using QuEChERS as sample preparation. For application in cosmetic samples, the original QuEChERS method was modified and optimized by evaluate of different solvents for extraction and sorbents for clean up step. Increases at recoveries of analytes were obtained employing acetone as solvent and PSA for clean up step, showed recoveries between 83.7% and 88.6% for all analytes. The method was validated according to ANVISA (linear range: 0.1 to 2.5 µg mL-1 for MP and PP, and 1.5 to 6.0 µg mL-1 for FE). Precision was evaluated by repeatability and intermediate precision with coefficients of variation (%) lower than 10% in all concentrations analysed, and accuracy was evaluated, with values ranging from 93.77% to 108.13%. The QuEChERS-HPLC-DAD method was tested in real samples (moisturizing cream and lotion, cleansing gel), where the concentration values were found below the maximum limit established by ANVISA.
DOI: 10.6084/m9.figshare.14278788.v1
title: OPTIMIZATION AND VALIDATION OF QuEChERS BASED METHOD FOR DETERMINATION OF PRESERVATIVES IN COSMETICS BY HPLC-DAD

description: Parabens are widely used as preservatives in the last decades. Others preservatives such as 2-phenoxyethanol, which in addition to his good antimicrobial activity, has low allergenic potential as well others properties of interest to the cosmetic industry. In this work was developed a method for determination of methylparaben (MP), propylparaben (PP) and 2-phenoxyethanol (FE) in cosmetic products by HPLC-DAD using QuEChERS as sample preparation. For application in cosmetic samples, the original QuEChERS method was modified and optimized by evaluate of different solvents for extraction and sorbents for clean up step. Increases at recoveries of analytes were obtained employing acetone as solvent and PSA for clean up step, showed recoveries between 83.7% and 88.6% for all analytes. The method was validated according to ANVISA (linear range: 0.1 to 2.5 µg mL-1 for MP and PP, and 1.5 to 6.0 µg mL-1 for FE). Precision was evaluated by repeatability and intermediate precision with coefficients of variation (%) lower than 10% in all concentrations analysed, and accuracy was evaluated, with values ranging from 93.77% to 108.13%. The QuEChERS-HPLC-DAD method was tested in real samples (moisturizing cream and lotion, cleansing gel), where the concentration values were found below the maximum limit established by ANVISA.
DOI: 10.6084/m9.figshare.14278790
title: JUDD-OFELT ANALYSIS OF Tb3+ AND UPCONVERSION STUDY IN Yb3+-Tb3+ CO-DOPED CALIBO GLASSES

description: We report on the study of the spectroscopic properties in Ytterbium-Terbium (Yb3+-Tb3+) co-doped calcium lithium borate (CaLiBO) glasses, with the study’s focus being on the upconversion process. Intensity parameters Ωλ for CaLiBO:Tb3+ are determined by the Judd-Ofelt method to be Ω2 = 15.5 × 10-20 cm2, Ω4 = 1.90 × 10-20 cm2 and Ω6 = 3.69 × 10-20 cm2. We have also obtained electric-dipole (and magnetic-dipole) radiative transition probabilities, branching ratios, and lifetime for the Tb3+:5D4 and 5D3 levels. In addition, an evaluation of the upconversion processes by luminescence and time-resolved spectroscopy were carried out. The upconversion rise and decay times, energy transfer probability from Yb3+ to Tb3+ ions, and the efficiency of the processes that depopulate the Tb3+:5D4 level after resonantly pumping the Yb3+:2F5/2 level were estimated. Our results showed that a cooperative energy transfer (CET) from two Yb3+ ions to one Tb3+ ion is the origin of the Tb3+ upconversion luminescence in the visible region. While, CET followed of the cross relaxation or/and excited state absorption is responsible for the upconversion luminescence in the ultraviolet region.
DOI: 10.6084/m9.figshare.14278793
title: ON THE INFLUENCE OF THE COMPOSITION OF Pt-Ir/C NANOWIRES ON THEIR ACTIVITY TOWARDS THE ELECTROCHEMICAL OXIDATION OF ETHANOL IN ACID MEDIA

description: Carbon-supported platinum-iridium nanowire-shape electrocatalysts containing 20% of metallic loading were synthesized by chemical reduction method using formic acid as a reducing agent and tested towards the oxidation of ethanol in acidic medium. The developed electrocatalysts were synthesized with the following compositions: Pt0.9Ir0.1/C, Pt0.8Ir0.2/C, Pt0.7Ir0.3/C, Pt0.6Ir0.4/C and Pt0.5Ir0.5/C using for comparison the commercial Pt/C Alfa Aesar catalyst. Physico-chemical characterization was performed using X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray fluorescence (XRF, for chemical composition) techniques. All the nanowires present a face-centered cubic crystalline structure of the platinum with modifications in the lattice parameter due to the inclusion of iridium. The XRF analyzes show that the theoretical compositions of the synthesized catalysts are very close to the experimental nominal values. TEM analyses showed the formation of nanowires by the synthesis method used. The electrochemical results on the oxidation of ethanol show that the addition of a second metal to the platinum in the composition of the nanowires increases the catalytic activity of the electrode. The nanowire catalysts with low Ir content (Pt0.9Ir0.1/C, Pt0.8Ir0.2/C, Pt0.7Ir0.3/C) present the best outcomes under the analyzed conditions and are promising for application as anodes in direct ethanol fuel cells.
DOI: 10.6084/m9.figshare.11997132
title: METABOLIC PROFILE OF THE POLAR EXTRACTS OF THE LEAVES, BRANCHES AND BARKS OF Copaifera multijuga HAYNE (COPAÍBA mari-mari AMAZÔNIA) BY ESI-MS

description: Copaifera multijuga Hayne is the main species of the genus in the Amazon region, being exploited for copaiba oil production mainly because of its therapeutic properties. The plant parts (leaves, branches, and barks) are widely used in folk medicine. However, they are little explored in terms of chemical composition. In this study, the polar extracts of leaves, branches, and barks of the species were analysed by direct infusion in ESI-MS with the aid of reference standards and MS2 fragmentation experiments. Twenty-six substances (carboxylic acids, flavonoids, condensed tannins, a diterpene and fifteen isomers of galoylquinic acids) were detected. Metabolic profiles were similar between extracts of leaves and branches, especially with the detection of galloylquinic acids and carboxylic acids. In bark extract, condensed tannins epicatechin-(4β-8)-epiafzelechin (dimer) and epicatechin-(4β-8)-epiafzelechin-(4β-8)-epiafzelechin (trimer) were detected. The PCA showed differences and similarities in the chemical composition of the copaíba mari-mari extracts. Thus, galloylquinic acids and flavonoids kaempferol, 7-O-methyl-kaempferol, quercetin-3-O-L-pentoside, and quercetin-3-O-L-rhamnoside are described for the first time in C. multijuga. The phytotherapeutic properties of teas of the plant parts of the species may be associated with the suggested polyphenols.
DOI: 10.6084/m9.figshare.14278793.v1
title: ON THE INFLUENCE OF THE COMPOSITION OF Pt-Ir/C NANOWIRES ON THEIR ACTIVITY TOWARDS THE ELECTROCHEMICAL OXIDATION OF ETHANOL IN ACID MEDIA

description: Carbon-supported platinum-iridium nanowire-shape electrocatalysts containing 20% of metallic loading were synthesized by chemical reduction method using formic acid as a reducing agent and tested towards the oxidation of ethanol in acidic medium. The developed electrocatalysts were synthesized with the following compositions: Pt0.9Ir0.1/C, Pt0.8Ir0.2/C, Pt0.7Ir0.3/C, Pt0.6Ir0.4/C and Pt0.5Ir0.5/C using for comparison the commercial Pt/C Alfa Aesar catalyst. Physico-chemical characterization was performed using X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray fluorescence (XRF, for chemical composition) techniques. All the nanowires present a face-centered cubic crystalline structure of the platinum with modifications in the lattice parameter due to the inclusion of iridium. The XRF analyzes show that the theoretical compositions of the synthesized catalysts are very close to the experimental nominal values. TEM analyses showed the formation of nanowires by the synthesis method used. The electrochemical results on the oxidation of ethanol show that the addition of a second metal to the platinum in the composition of the nanowires increases the catalytic activity of the electrode. The nanowire catalysts with low Ir content (Pt0.9Ir0.1/C, Pt0.8Ir0.2/C, Pt0.7Ir0.3/C) present the best outcomes under the analyzed conditions and are promising for application as anodes in direct ethanol fuel cells.
DOI: 10.6084/m9.figshare.14278794
title: MUNDAU-MANGUABA LAGOON ESTUARY COMPLEX: CHARACTERIZATION OF NATURAL ORGANIC MATTER AND INTERACTION WITH Hg2+

description: The Mundaú-Manguaba lagoon estuary complex is the most important ecosystem in the state of Alagoas, and a source of sustenance for a large number of the state’s inhabitants. However, degradation by anthropic sources has been causing impacts on this ecosystem. Understanding the characteristics of the natural organic material of the waters of the mundaú-manguaba lagoon complex is extremely important to understand the interaction dynamics of the contaminants in these lagoons. Thus, the objective of this work was to extract and characterize aquatic humic substances from the Mundau-Manguaba lagoon complex and to evaluate the interaction of this organic material with mercury ions. The profile of the aquatic humic substances of the respective lagoons evidenced the greater influence of aliphatic groups in their structures. The interactions of aquatic humic substances and mercury ions are directly related to the oxygen groups in their structures, corroborated by Principal Component Analysis. Thus, understanding the water and organic matter characteristics present in the Mundaú-Manguaba estuarine lagoon complex is fundamental for establishing strategies, seeking the preservation of this ecosystem and remediation of environmental contamination.