cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.14278942
title: DEVELOPMENT OF AN ANALYTICAL METHOD FOR THE DETERMINATION OF LEAD BASED ON LOCAL SURFACE PLASMON RESONANCE OF SILVER NANOPARTICLES

description: Lead is environmental pollutant that even in low trace is harmful for human health and wildlife. In this study we presented a colorimetric method for determination of Pb2+ in water by aggregation of silver nanoparticles capped citrate in the presence of deferoxamine as chelating agent. Silver nanoparticles were prepared by reduction of AgNO3 with NaBH4. In the presence of Pb2+, mixture of silver nanoparticles capped citrate and deferoxamine aggregated and color of solution changed from light yellow to violet that depends on Pb2+ concentration. As a result of aggregation, local surface plasmon resonance (LSPR) band of silver nanoparticles around 440 nm decreases and a new band appears at 580 nm that depend on Pb2+ concentration. Under optimized conditions, linear relation of concentration of Pb2+ and absorbance ratio (A580/A440), was from 0.19 to 1.29 µmol L-1 and limit of detection of 0.056 µmol L-1 was found. Control experiments with the addition of 10 other metal ions (Ni2+, Cu2+, Ca2+, Al3+, Co2+, K+, Ba2+, Zn2+, Mg2+, Hg2+) did not result in a distinct change in the color or in the absorption spectra. This approach was successfully tested for determination of Pb2+ in well and tap water.
DOI: 10.6084/m9.figshare.14278940
title: PLATINUM(II) COMPLEXES CONJUGATED AND ANALOGOUS TO O-GLYCOSIDES: SYNTHESIS, STRUCTURAL CHARACTERIZATION AND ANTITUMOR ACTIVITY

description: The synthesis, characterization, cytotoxicity and antitumor activity of platinum(II) complexes coordinated to O-glycoside and analogous is reported. Through the acute toxicity tests, it was possible to fit the complexes into categories according to the OECD protocol. The cis-[PtCl2(C6H14S2O2)-κ2S] complex was classified in category 3 and the cis-[PtCl2(C26H38O12S2)-κ2S] complex was classified in category 4. This result demonstrates the lower toxicity achieved by the glycoside in comparison with its analogous system. Evaluations of tumor masses extracted from mice inoculated with Ehrlich carcinoma demonstrated percent inhibition similar to cisplatin and synthesized platinum complexes. Cisplatin showed 59% inhibition, while cis-[PtCl2(C6H14S2O2)-κ2S] and cis-[PtCl2(C26H38O12S2)-κ2S] complexes presented 57% and 59%, respectively. Although the glycosidic compounds exhibit tumor activity, reported in the literature, the presence of platinum ion was shown to be determinant for antitumor action according with the compounds tested, since the glycosidic ligand presented tumor inhibition of only 38%, with a similar antitumor activity in relation to cisplatin.
DOI: 10.6084/m9.figshare.14278942.v1
title: DEVELOPMENT OF AN ANALYTICAL METHOD FOR THE DETERMINATION OF LEAD BASED ON LOCAL SURFACE PLASMON RESONANCE OF SILVER NANOPARTICLES

description: Lead is environmental pollutant that even in low trace is harmful for human health and wildlife. In this study we presented a colorimetric method for determination of Pb2+ in water by aggregation of silver nanoparticles capped citrate in the presence of deferoxamine as chelating agent. Silver nanoparticles were prepared by reduction of AgNO3 with NaBH4. In the presence of Pb2+, mixture of silver nanoparticles capped citrate and deferoxamine aggregated and color of solution changed from light yellow to violet that depends on Pb2+ concentration. As a result of aggregation, local surface plasmon resonance (LSPR) band of silver nanoparticles around 440 nm decreases and a new band appears at 580 nm that depend on Pb2+ concentration. Under optimized conditions, linear relation of concentration of Pb2+ and absorbance ratio (A580/A440), was from 0.19 to 1.29 µmol L-1 and limit of detection of 0.056 µmol L-1 was found. Control experiments with the addition of 10 other metal ions (Ni2+, Cu2+, Ca2+, Al3+, Co2+, K+, Ba2+, Zn2+, Mg2+, Hg2+) did not result in a distinct change in the color or in the absorption spectra. This approach was successfully tested for determination of Pb2+ in well and tap water.
DOI: 10.6084/m9.figshare.14278937
title: DURABILITY OF HDPE GEOMEMBRANES: AN OVERVIEW

description: The polymer demand for geotechnical applications has been growing. The geomembrane is a geosynthetic, manufactured, polymeric product and is often specified in environmental projects. Geomembranes started to be used in the 1930s but became more widespread in the 1940s. In the 1970s, geomembranes began to be specified for landfills. Over the past forty years, millions of square meters of HDPE geomembrane have been used in different applications. One of the most important issues for HDPE geomembranes is durability, involving very long-term property requirements. A rupture in the liner that has a geomembrane may provide losses in terms of human lives, environmental impacts, and financial costs. This paper summarizes the mechanisms and concepts involved in the HDPE geomembrane aging and describes the important contributions of laboratory and field studies over the years around the world. Different conditions and exposures drive the HDPE geomembrane behavior, including field temperature conditions and contact with different chemical substances. Accelerated laboratory testing with HDPE geomembrane simulating field boundary conditions is critical to ensure proper use of this geosynthetic in the future.
DOI: 10.6084/m9.figshare.14278940.v1
title: PLATINUM(II) COMPLEXES CONJUGATED AND ANALOGOUS TO O-GLYCOSIDES: SYNTHESIS, STRUCTURAL CHARACTERIZATION AND ANTITUMOR ACTIVITY

description: The synthesis, characterization, cytotoxicity and antitumor activity of platinum(II) complexes coordinated to O-glycoside and analogous is reported. Through the acute toxicity tests, it was possible to fit the complexes into categories according to the OECD protocol. The cis-[PtCl2(C6H14S2O2)-κ2S] complex was classified in category 3 and the cis-[PtCl2(C26H38O12S2)-κ2S] complex was classified in category 4. This result demonstrates the lower toxicity achieved by the glycoside in comparison with its analogous system. Evaluations of tumor masses extracted from mice inoculated with Ehrlich carcinoma demonstrated percent inhibition similar to cisplatin and synthesized platinum complexes. Cisplatin showed 59% inhibition, while cis-[PtCl2(C6H14S2O2)-κ2S] and cis-[PtCl2(C26H38O12S2)-κ2S] complexes presented 57% and 59%, respectively. Although the glycosidic compounds exhibit tumor activity, reported in the literature, the presence of platinum ion was shown to be determinant for antitumor action according with the compounds tested, since the glycosidic ligand presented tumor inhibition of only 38%, with a similar antitumor activity in relation to cisplatin.
DOI: 10.6084/m9.figshare.14278944
title: CELLULOSE NANOFIBERS FROM CASSAVA AGRO-INDUSTRIAL WASTE AS REINFORCEMENT IN PVA FILMS

description: Cellulose nanofibers (CNF) have been applied in composite systems due to the abundance of raw material, excellent mechanical and thermal properties. In this work, CNF was prepared from agroindustrial waste and used in specified amounts in polyvinyl alcohol (PVA) composites. The FTIR spectra of CNF, chemically purified cellulose (CPC) and Cassava Agro-industrial Waste (CAW) indicate the removal of hemicellulose and lignin. The increase of the crystallinity phase in CNF was observed, by XRD analysis and neither is observed the transition from cellulose I to II. Thermogravimetric analysis showed displacement that the initial degradation of the CNF over 43 °C degradation proceeds at single step. The chemical and dimensional homogeneity of CNF can be observed with the calculation of the crystalline phase content obtained by deconvoluted dTG curve and XRD spectra, obtaining 80% crystallinity by both techniques. SEM micrographs showed fibers with diameters of 22.30 ± 1.52 nm. An increase in the mechanical properties of PVA was observed with the addition of CNF. With 2.5% CNF in the PVA, the elastic module increased by approximately three times, with the addition of 10% CNF, a saturated system with poor mechanical properties was observed.
DOI: 10.6084/m9.figshare.14278946
title: BIOACESSIBILITY OF ZINC, CALCIUM AND PHOSPHORUS IN SOYBEAN EXTRACT AND COW, GOAT, SHEEP MILK SAMPLES

description: This work describes the bioaccessibility in vitro simulated gastric digestion for levels of Zn, Ca, and P in milk and soybean extract samples. Total and dialyzed levels were determined by ICP OES. According to results of the dialyzed samples, it can be concluded that in 250 mL of milk (a glass) the body can be absorb about 1.2 ± 0.2 mg, 14.8 ± 1.2 mg, 4.5 ± 0.8 mg, 2.2 ± 0.4 mg and 4.9 ± 0.6 mg of Zn; 2079 ± 133 mg, 305 ± 4 mg, 2396 ± 16 mg, 2444 ± 54 mg, and 1527 ± 71 mg of Ca; and 2023 ± 275 mg, 811 ± 14 mg, 2688 ± 39 mg, 5089 ± 474 mg and 3467 ± 63 mg of P for raw sheep’s milk, soybean, raw cow’s milk, UHT goat’s milk, and UHT cow’s milk, respectively. These results correspond to approximately 45, 118, and 267% of diary human needed of Zn, Ca, and P, respectively. Accuracy was verified using CRM (NIST 8435) for total levels, and dialyzed samples were compared with FAAS, statistically evaluated by Student’s t-test. Results confirmed the methodology efficiency and allowed an estimate of the bioacessibility of nutrients.
DOI: 10.6084/m9.figshare.14278946.v1
title: BIOACESSIBILITY OF ZINC, CALCIUM AND PHOSPHORUS IN SOYBEAN EXTRACT AND COW, GOAT, SHEEP MILK SAMPLES

description: This work describes the bioaccessibility in vitro simulated gastric digestion for levels of Zn, Ca, and P in milk and soybean extract samples. Total and dialyzed levels were determined by ICP OES. According to results of the dialyzed samples, it can be concluded that in 250 mL of milk (a glass) the body can be absorb about 1.2 ± 0.2 mg, 14.8 ± 1.2 mg, 4.5 ± 0.8 mg, 2.2 ± 0.4 mg and 4.9 ± 0.6 mg of Zn; 2079 ± 133 mg, 305 ± 4 mg, 2396 ± 16 mg, 2444 ± 54 mg, and 1527 ± 71 mg of Ca; and 2023 ± 275 mg, 811 ± 14 mg, 2688 ± 39 mg, 5089 ± 474 mg and 3467 ± 63 mg of P for raw sheep’s milk, soybean, raw cow’s milk, UHT goat’s milk, and UHT cow’s milk, respectively. These results correspond to approximately 45, 118, and 267% of diary human needed of Zn, Ca, and P, respectively. Accuracy was verified using CRM (NIST 8435) for total levels, and dialyzed samples were compared with FAAS, statistically evaluated by Student’s t-test. Results confirmed the methodology efficiency and allowed an estimate of the bioacessibility of nutrients.
DOI: 10.6084/m9.figshare.14278949
title: EXTRACTION OF MONOMERS OF HYDROLYSABLE TANNINS FROM PODS OF Libidibia ferrea (Mart. ex Tul.) L. P. QUEIROZ: EFFECTS OF SOLVENT AND AMOUNT OF DRUG USING RESPONSE-SURFACE METHODOLOGY AND DESIRABILITY PROFILE

description: In this study was evaluated the influence of the extraction factors on the extract’s properties to improve the recovery of high concentrations of the phytochemicals important for the biological activities from pods of Libidibia ferrea (Mart. ex Tul.) L. P. Queiroz. The extracts were obtained by turbo-extraction and a factorial design 32 was used to study the importance of the drug amount (5, 10 or 15 g) and the solvent (Ethanol 40, 60 or 80%, v/v) on the variables of response, and the optimization was performed by Response Surface Methodology (RSM) and Desirability profile. Mathematical models were fitted according to experimental data and the validated equations were used to generate RSM for each dependent variable (dry residue; total polyphenol content; content of gallic acid and ellagic acid; and, efficiency of extraction). The factors studied within the applied experimental field presented different influence profiles for the responses, and significant interactions between linear and quadratic terms. The statistical analysis showed high R2 &gt; 0.99. The RSM and Desirability (&gt; 0.95) allowed to show that the optimum conditions to produce extractive solutions of Libidibia ferrea with high efficiency for ellagic acid and gallic acid were 15 g and ethanol 40%.
DOI: 10.6084/m9.figshare.14278944.v1
title: CELLULOSE NANOFIBERS FROM CASSAVA AGRO-INDUSTRIAL WASTE AS REINFORCEMENT IN PVA FILMS

description: Cellulose nanofibers (CNF) have been applied in composite systems due to the abundance of raw material, excellent mechanical and thermal properties. In this work, CNF was prepared from agroindustrial waste and used in specified amounts in polyvinyl alcohol (PVA) composites. The FTIR spectra of CNF, chemically purified cellulose (CPC) and Cassava Agro-industrial Waste (CAW) indicate the removal of hemicellulose and lignin. The increase of the crystallinity phase in CNF was observed, by XRD analysis and neither is observed the transition from cellulose I to II. Thermogravimetric analysis showed displacement that the initial degradation of the CNF over 43 °C degradation proceeds at single step. The chemical and dimensional homogeneity of CNF can be observed with the calculation of the crystalline phase content obtained by deconvoluted dTG curve and XRD spectra, obtaining 80% crystallinity by both techniques. SEM micrographs showed fibers with diameters of 22.30 ± 1.52 nm. An increase in the mechanical properties of PVA was observed with the addition of CNF. With 2.5% CNF in the PVA, the elastic module increased by approximately three times, with the addition of 10% CNF, a saturated system with poor mechanical properties was observed.
DOI: 10.6084/m9.figshare.14278949.v1
title: EXTRACTION OF MONOMERS OF HYDROLYSABLE TANNINS FROM PODS OF Libidibia ferrea (Mart. ex Tul.) L. P. QUEIROZ: EFFECTS OF SOLVENT AND AMOUNT OF DRUG USING RESPONSE-SURFACE METHODOLOGY AND DESIRABILITY PROFILE

description: In this study was evaluated the influence of the extraction factors on the extract’s properties to improve the recovery of high concentrations of the phytochemicals important for the biological activities from pods of Libidibia ferrea (Mart. ex Tul.) L. P. Queiroz. The extracts were obtained by turbo-extraction and a factorial design 32 was used to study the importance of the drug amount (5, 10 or 15 g) and the solvent (Ethanol 40, 60 or 80%, v/v) on the variables of response, and the optimization was performed by Response Surface Methodology (RSM) and Desirability profile. Mathematical models were fitted according to experimental data and the validated equations were used to generate RSM for each dependent variable (dry residue; total polyphenol content; content of gallic acid and ellagic acid; and, efficiency of extraction). The factors studied within the applied experimental field presented different influence profiles for the responses, and significant interactions between linear and quadratic terms. The statistical analysis showed high R2 &gt; 0.99. The RSM and Desirability (&gt; 0.95) allowed to show that the optimum conditions to produce extractive solutions of Libidibia ferrea with high efficiency for ellagic acid and gallic acid were 15 g and ethanol 40%.
DOI: 10.6084/m9.figshare.14278954
title: IMPLEMENTATION OF THE CLAYFF FORCE FIELD IN GROMACS: AN APPLICATION IN KAOLINITE STRUCTURE

description: Molecular dynamics techniques are increasingly being used for material science studies, being a theoretical approach based on molecular mechanics studies. GROMACS is a free software that allows the development of simulations of various types of molecules, from biological molecules to inorganic structures associated with the area of materials, requiring the system parameterization according to the force fields used in the simulation. ClayFF is a force field used for crystalline clay structures and has been applied in several articles published in scientific journals. The objective of this work was to present a didactic approach to the implementation of ClayFF in GROMACS and the force field was used to simulate a kaolinite structure as an example, demonstrating the implementation for students and researchers in the field.
DOI: 10.6084/m9.figshare.14278951
title: INCORPORATION OF ESSENTIAL OILS FROM Piper aduncum INTO FILMS MADE FROM ARROWROOT STARCH: EFFECTS ON THEIR PHYSICOCHEMICAL PROPERTIES AND ANTIFUNGAL ACTIVITY

description: Starch is a promising source of biopolymers and the incorporation of essential oils (EOs) into it can improve some biological properties of films. This study aimed at developing and characterizing barrier, biodegradability and optical properties of biopolymeric films made from arrowroot starch and at incorporating EOs from Piper aduncum leaves and inflorescences in order to analyze their antifungal activity against Rhizopus microsporus and Colletotrichum gloeosporioides. The casting method was used for developing arrowroot starch films and incorporating EOs into them. Resulting films exhibited satisfactory barrier properties, low water vapor permeability (WVP), transparency and good barrier property against UV-vis light, besides being 100% biodegradable. In addition, films enriched with EOs at 0.75% and 1.0% revealed promising antifungal activity. Results showed, for the first time, that arrowroot starch enriched with EOs from P. aduncum can potentially be used as an active film due to its excellent physicochemical properties and antimicrobial activity.
DOI: 10.6084/m9.figshare.14278953
title: THEORETICAL STUDIES ON DIACETONEDIPEROXIDE DERIVATIVES AND COMPARISONS WITH OTHER MULTI-PEROXIDIC COMPOUNDS

description: Diacetonediperoxide (DADP) derivatives were investigated with density functional theory (DFT) methods at the DFT-B3LYP and M06-2X/6-311++G (d, p) levels and were also compared with other multi-peroxidic compounds. The investigated derivatives were 3,6-dimethyl-3,6-diamine-1,2,4,5-tetraoxane (DADPNH2), 3,6-dimethyl-3,6-dinitro-1,2,4,5-tetraoxane (DADPNO2), and 3,6-dimethyl-3,6-bis(trifluoromethyl)-1,2,4,5-tetraoxane (DADP3F). The investigations were focused on detonation performance and stability which were determined according to geometrical and electronic structure. The results of the simulation revealed that DADP derivatives are less sensitive than some other organic peroxidic compounds. In addition, detonation performance, including explosion heat (Q), detonation velocity (D), and detonation pressure (P), was estimated according to density and heat of formation using EXPLO 5 software. The results revealed that DADPNO2 has better detonation performance (Q = 5543 kJ kg-1, P = 23.7 GPa, D = 7631 m s-1) compared with traditional explosive 2,4,6-trinitrotoluene (TNT; Q = 5418 kJ kg-1, P = 19.0 GPa, D = 6950 m s-1). Therefore, it is a novel candidate for use as an energetic material.
DOI: 10.6084/m9.figshare.14278953.v1
title: THEORETICAL STUDIES ON DIACETONEDIPEROXIDE DERIVATIVES AND COMPARISONS WITH OTHER MULTI-PEROXIDIC COMPOUNDS

description: Diacetonediperoxide (DADP) derivatives were investigated with density functional theory (DFT) methods at the DFT-B3LYP and M06-2X/6-311++G (d, p) levels and were also compared with other multi-peroxidic compounds. The investigated derivatives were 3,6-dimethyl-3,6-diamine-1,2,4,5-tetraoxane (DADPNH2), 3,6-dimethyl-3,6-dinitro-1,2,4,5-tetraoxane (DADPNO2), and 3,6-dimethyl-3,6-bis(trifluoromethyl)-1,2,4,5-tetraoxane (DADP3F). The investigations were focused on detonation performance and stability which were determined according to geometrical and electronic structure. The results of the simulation revealed that DADP derivatives are less sensitive than some other organic peroxidic compounds. In addition, detonation performance, including explosion heat (Q), detonation velocity (D), and detonation pressure (P), was estimated according to density and heat of formation using EXPLO 5 software. The results revealed that DADPNO2 has better detonation performance (Q = 5543 kJ kg-1, P = 23.7 GPa, D = 7631 m s-1) compared with traditional explosive 2,4,6-trinitrotoluene (TNT; Q = 5418 kJ kg-1, P = 19.0 GPa, D = 6950 m s-1). Therefore, it is a novel candidate for use as an energetic material.
DOI: 10.6084/m9.figshare.14278955
title: DIRECTED EVOLUTION OF ENZYMES: SMALL CHANGES, BETTER BIOCATALYSTS

description: Biocatalysis is now a mature field, both in the laboratory and industrial scale. This approach counts on enzyme high selectivity, biodegradability, elegant control over the outcome of reaction conditions and as a possible solution to address some challenges in Green Chemistry faced by synthetic organic chemists. However, many wild-type ready-to-use enzymes were not designed to accommodate the organic substrates needed by today’s demands. Or they do not fit a predefined optimum process condition or even, useful reactions are not accessible because there is no enzyme counterpart for metallo- and organocatalysts. This review will give a brief introduction on the protein engineering tools (directed evolution, rational design, and semi-rational design) and will focus on directed evolution of enzymes, their impact in chemistry with examples from production of commodity chemicals to pharmaceutical intermediates and its potential as a tool to achieve greener chemistry criteria will be discussed.
DOI: 10.6084/m9.figshare.14278955.v1
title: DIRECTED EVOLUTION OF ENZYMES: SMALL CHANGES, BETTER BIOCATALYSTS

description: Biocatalysis is now a mature field, both in the laboratory and industrial scale. This approach counts on enzyme high selectivity, biodegradability, elegant control over the outcome of reaction conditions and as a possible solution to address some challenges in Green Chemistry faced by synthetic organic chemists. However, many wild-type ready-to-use enzymes were not designed to accommodate the organic substrates needed by today’s demands. Or they do not fit a predefined optimum process condition or even, useful reactions are not accessible because there is no enzyme counterpart for metallo- and organocatalysts. This review will give a brief introduction on the protein engineering tools (directed evolution, rational design, and semi-rational design) and will focus on directed evolution of enzymes, their impact in chemistry with examples from production of commodity chemicals to pharmaceutical intermediates and its potential as a tool to achieve greener chemistry criteria will be discussed.
DOI: 10.6084/m9.figshare.14278958
title: SYNTHESIS AND CHARACTERIZATION OF ENVIRONMENTALLY FRIENDLY QUANTUM DOTS, A SIMPLE WAY TO EXEMPLIFY AND EXPLORE NANOSCIENCE AND NANOTECHNOLOGY IN UNDERGRADUATE EDUCATION

description: Nanotechnologies and nanomaterials are very current and interesting topics and can be used as interdisciplinary tools in education. They can be used to work in a practical and interesting way with lots of subjects. In chemistry teaching it can be particularly important to consolidate the nanomaterials, nanotechnology and characterization teaching. Among the nanomaterials, quantum dots (QDs) can be highlighted due to their interesting optical and electronical properties. Some of the topics that can be discussed related to them are the nanoparticles synthesis, spectroscopies and optical characterization, X-ray diffractometry and structural characterization, surface ligands, semiconductor materials, electronic transition, solid crystalline structure, colloidal synthesis, among many other subjects. The application of the experiment of synthesis and characterization of environmentally friendly quantum dots to students of the discipline “Solid State Chemistry” of the chemistry undergraduate course, allowed the contact of students with materials of great technological interest. Being a material widely studied by various research groups around the world. The experiment proved to be an interesting way to introduce students to a material of great technological interest, in a simple and accessible way. It aroused the interest of the students while allowing the practical application of the acquired knowledge.