cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.14303825.v1
title: Optimization of Alkaline, Acidic, Ionic Liquid and Oxidative Pretreatments for Coconut Waste Conversion into Fermentable Sugars

description: Cocos nucifera L. is a palm tree of paramount importance in the food and chemistry industries, although over 50% of its biomass is discarded as waste. The aim of the study is to investigate different pretreatments in to coconut husks (CH), based on acid, alkaline, ionic liquid (IL), and peroxidative, in order to produce fermentable sugars. Severity factors were calculated for pretreatments; values ranged from 0.3 to 1.7 for peroxide, from 0.01 to 1.4 for alkaline, from 1.4 to 2.8 for acid and from 2.0 to 3.0 for ionic liquid. Pretreatments were optimized (time and temperature) to maximize the sugar yield and to remove the total lignin after acid hydrolysis. Reducing sugar yield (70%) was higher when CH waste was alkaline-pretreated for 2 h at 76.21 °C. The highest lignin removal rate was recorded when alkaline (21.4%) and peroxide solutions (27.2%) were used. The IL did not increase sugar yield and was not effective in lignin removal. These outcomes were confirmed through infrared spectroscopy, whereas scanning electron microscopy showed increased biomass porosity during alkaline, acid and peroxide pretreatments. The IL showed little and non-significant changes. The crystallinity index notably increased after each pretreatment; besides, it was directly associated with sugar content.
DOI: 10.6084/m9.figshare.14303823.v1
title: In silico Risk Assessment Studies of New Psychoactive Substances Derived from Amphetamines and Cathinones

description: The amount and variety of new psychoactive substances (NPS) are expanding, and there are difficulties in assessing their risks. In this regard, in silico methods are potentially useful to predict NPS properties faster and at a lower cost. In this work a quantitative structure-activity relationship (QSAR) model was used to verify the risk of drugs derived from amphetamines and cathinones. A dataset of 26 derivatives with in vitro affinity for norepinephrine transporter (NET) was selected. To ensure reproducibility of the results, only geometric molecular descriptors (AM1 (Austin model 1) level) obtained from the platform ChemDes and ordered predictors selection (OPS) were used. The model presents good internal statistics (n = 23; coefficient of determination (R2) = 0.914). The small number of samples was divided into seven training sets (n = 17) and seven test sets (n = 6). The average R2pred = 0.754 showed that the model has good predictive capacity. Based on the tests, this model can accurately predict the risk range of three previously selected derivatives: methedrone (low), ethcathinone (medium), and methamphetamine (high), even when only data referring to NET are employed. We used these data to create a simple free program in Java that focuses on the risk assessment of recreational drugs belonging to this class of compounds.
DOI: 10.6084/m9.figshare.14303821.v1
title: Assessment of Reaction Parameters in the Polymeric Carbon Nitride Thermal Synthesis and the Influence in Photocatalytic Hydrogen Production

description: In this work, the reaction parameters for polymeric carbon nitride synthesis by thermal polycondensation were assessed, such as type of precursor, heating rate and time of thermal treatment, in order to obtain crystalline materials with high photocatalytic performance. All synthesized materials were tested as photocatalysts in hydrogen production using ethylenediaminetetraacetic acid (EDTA) as a sacrificial reactant under visible light irradiation (λ ≥ 420 nm). The synthesis condition capable to obtain the material that reached the best performance in photocatalytic hydrogen production was using thiourea as the precursor, due to the band gap narrowing and charge recombination suppression; an intermediate heating rate (5 ºC min-1) and a longer thermal treatment time (6 h) that yielded a better crystalline solid. The combination of these effects led the S-doped polymeric carbon nitride (SPCN4 sample) to a higher photocatalytic activity, reaching the maximum hydrogen production rate of 214.75 µmol g-1 h-1.
DOI: 10.6084/m9.figshare.14303819.v1
title: Simple GFAAS Method for Determination of Pb, As, and Cd in Cannabidiol Extracts Used for Therapeutic Purposes

description: Cannabis sativa has many promising medicinal applications for the mitigation, or even cure, of chronic diseases. The high bioaccumulation potential of C. sativa enables its use for the phytoremediation and detoxification of soil, may increase the levels of inorganic elements in products such as cannabidiol (CBD) extracts being necessary the evaluation/monitoring of the level of inorganic components, mainly the toxic species in these formulations. An analytical method employing graphite furnace atomic absorption spectrometry (GFAAS) was developed for the quantification of Pb, As, and Cd in commercial CBD extracts and homemade samples. The alkaline solubilization was employed in agreement with the external analytical curve, in a robust method. The limits of quantification were 0.26 (Pb), 0.067 (As), and 0.011 µg g-1 (Cd), with satisfactory accuracy (80-120%) and relative standard deviation (RSD) values &lt; 7%. The CBD extracts presented levels of Pb, As and Cd below the maximum limits established by regulatory agencies.
DOI: 10.6084/m9.figshare.14303817.v1
title: Exploratory Analysis of the Distribution of Lignin and Cellulose in Woods by Raman Imaging and Chemometrics

description: The determinations of cellulose and lignin are important in wood analysis from both perspectives: chemistry composition, commercial and industrial application of woods. In this context, Raman image spectroscopy was applied in the determination of cellulose and lignin distribution in wood surfaces of Swietenia macrophylla King (Mahogany) and Eucalyptus hybrid (E. urophylla × E. camaldulensis). The relative concentration maps were obtained by applying a multivariate curve resolution procedure. The estimated Raman spectra for cellulose and lignin agrees with the ones available in the literature. The cellulose concentration maps showed similar variations for both studied species with an average value of nearly 85% as obtained by the reference method. The lignin concentration maps were somewhat different. The Eucalyptus hybrid presents a broader distribution (20 to 45%) while for Mahogany it is nearly constant, around 25%, with localized regions presenting contents of 45 to 65% of lignin. The reference method showed that the mean lignin content of both species is 27%. The cellulose and lignin concentration maps agree with the biological functions of the anatomic structures observed in the images.
DOI: 10.6084/m9.figshare.14303813.v1
title: Mapping Ethanol Production Sources in Brazil Through Stable Isotopes

description: Ethanol is a biofuel produced in Brazil through fermentation of sugarcane, requiring vast plantation areas and water availability. The present work aimed at testing isotopic markers as tools for ethanol source appointment or certification of origin. For this, oxygen and hydrogen isotopic patterns were determined in plant-water, soil-water, rainwater, and water from reservoirs and some rivers in four sugarcane crop areas. The isotopic fingerprint of carbon and hydrogen in ethanol produced in the respective mills was also determined. Samples were collected in 2011 and 2012 in crop areas of the state of Amazonas (North), Mato Grosso (Center-West), São Paulo (Southeast) and Rio Grande do Sul (South). The substantial and complex influence of the hydrological cycle on the ethanol δD and the small δ13C variations constrain the use of isotopes for the intended objectives.
DOI: 10.6084/m9.figshare.14303811.v1
title: Adsorption of Transition Metal Chlorides by Silica with Grafted 1-n-Propyl-3-Methylimidazolium Chloride

description: Silica with grafted 1-n-propyl-3-methylimidazolium chloride was investigated as adsorbent for the removal of cobalt(II), copper(II), zinc(II), cadmium(II) and mercury(II) chlorides from alcoholic and aqueous solutions. The adsorption proceeds via the formation of metal-chloride anionic complexes detained near the grafted organic cations as counterions. This conclusion is corroborated by the electronic and Raman spectra. The high removal degrees of the metal chlorides from solutions are easily reached. The adequate models of adsorption equilibria consider dissociation and auto-complexation of chlorides in solutions and formation of tri- and tetrachlorometallate anions in the solid phase. Also, the equilibrium constants for the CoCl2 and CuCl2 adsorption by several materials containing grafted organic cations and chloride counterions were recalculated in the framework of this model. The weak dependence of equilibrium constants on the nature of immobilized cations and carriers agrees with the established chemistry of metal chlorides fixation.
DOI: 10.6084/m9.figshare.14303809.v1
title: Multiple Dynamics of Hydrazone Based Compounds

description: Hydrazone derivatives of 2-quinolinecarboxaldehyde and 6-bromo-2-pyridinecarboxaldehyde were synthesized by sequence reactions with hydrazine derivatives. These compounds exhibited E/Z isomerization upon irradiation using a mercury lamp (250 W). The configurational changes were monitored by 1H nuclear magnetic resonance (NMR), UV-Vis and fluorescence spectroscopy. Data of concentration of the E/Z isomers versus time showed first order kinetics with constants ranging from 0.024 to 0.0799 min-1. The Z isomers were isolated by chromatographic methods and characterized by 1H NMR, UV-Vis and fluorescence spectroscopy and X-ray diffraction. The Z compounds are stable even in solution for several months. Such stability is due to a thermodynamic stabilization by the formation of an intramolecular hydrogen bond in the Z structure, which is not seen in the E configuration. Furthermore, some of the compounds were used as ligands for various metal centers (Zn2+, Co2+ and Hg2+) and their electronic properties were studied including measurements of cyclic voltammetry. The compounds studied herein allow their use as dynamic systems in dynamic combinatorial chemistry as their properties can be modulated by light, heat and the presence of metal centers. Besides, obtaining a metastable state (Z-isomer) allows the use of these compounds as photo-brakes, and therefore they can be implemented as molecular machines.
DOI: 10.6084/m9.figshare.14303807.v1
title: Investigation of the Environmental Transport of Human Pharmaceuticals to Surface Water: A Case Study of Persistence of Pharmaceuticals in Effluent of Sewage Treatment Plants and Hospitals in Malaysia

description: The present work reports the occurrence and monitoring of 11 pharmaceuticals (i.e., caffeine, prazosin, enalapril, carbamazepine, nifedipine, gliclazide, levonorgestrel, simvastatin, hydrochlorothiazide, diclofenac-Na and mefenamic acid) in surface water and in the influent and effluent of sewage treatment plants (STPs) and hospitals (HSPs). A total of 105 water samples were analyzed using solid-phase extraction combined with liquid chromatography-time-of-flight/mass spectrometry (SPE-LC-TOF/MS). The mean concentrations of the detected pharmaceuticals in STP influent and effluent ranged from &lt; limit of quantification (LOQ) to 3909 ng L−1 and 12 to 577 ng L−1, respectively. The mean concentrations of the detected pharmaceuticals in the hospital influent and effluent ranged from 28 to 1644 ng L−1 and 20 to 1540 ng L−1, respectively. The highest concentration detected in the sampling points was 9099 ng L−1 for caffeine in influent STP. The presence of prazosin has never been reported before in literature. In this study, prazosin was detected in all studied samples, and the highest concentration was 525 ng L−1 in influent STP. Chemometric analysis was used to assess the presence of pharmaceuticals in samples.
DOI: 10.6084/m9.figshare.14303805.v1
title: Structure of Humic Substances from Some Regions of the Amazon Assessed Coupling 3D Fluorescence Spectroscopy and CP/PARAFAC

description: The Amazon rainforest presents one of the greater biodiversity in the world and a huge and dynamic carbon reservoir, both in the vegetation and in the soil pools, so it is an attractive subject of study. In the present paper, humic acids from a toposequence of an Oxisol-Spodosol system associated with kaolin was studied using fluorescence emission-excitation matrix combined with parallel factor analysis. The combined techniques allowed to assess the intensities of the two different fluorophores associated with humic acid with core consistency diagnoses of 84.2%. The results for the Humiluvic Spodosol seem to corroborate the model of the supramolecular structure of humic acid, because the intensity ratio of fluorophores does not remain in the profile. Therefore, the use of these combined techniques can provide information about the transformation processes of humic substances in soils, becoming an interesting analytical tool for studying these substances of different soils.
DOI: 10.6084/m9.figshare.14303801.v1
title: Preliminary Investigation of Medicinal Herb Adulteration Using Comprehensive Two-Dimensional Gas Chromatography and Chemometric Analysis

description: Anise is frequently found among the ingredients described in the label of cosmetic products. However, the use of fennel instead of anise may occur due to the lower price of fennel. The main differences in volatile profile of anise and fennel fruits were, for the first time, evaluated using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection (GC×GC/TOFMS) and chemometric analysis. Aproximately 950 peaks were found in chromatograms of each sample and Fisher ratio appointed 31 volatile analytes as the most discriminating between anise and fennel samples. These 31 compounds were used in principal component analysis and canonical discriminant analysis that designated seven compounds (estragole, methyl eugenol, 4,5-dehydro-isolongifolene, calamenene, linalool, β-ocimene and fenchol) as the most important to verify the use of fennel or anise in personal care products. Among these seven compounds, thrree coeluted with other compounds and were correctly identified only with the use of GC×GC/TOFMS.
DOI: 10.6084/m9.figshare.14303800.v1
title: Brazilian Federal District Cocaine Chemical Profiling - Mass Balance Approach and New Adulterant Routinely Quantified (Aminopyrine)

description: From a set of 159 samples seized by Brazilian Federal Police between 2010 to 2013 in the Federal District, the major component chemical profiling routine analyses revealed the presence of cocaine with purity range of 5.5 to 99.9% (mean 69.8%). Most cocaine base samples show moderately and not oxidized levels, whereas cocaine hydrochloride samples exhibit moderate to high oxidation degrees. More than 40% of the analyzed samples did not have any adulterant. Phenacetin was the most abundant adulterant (24% average purity). Aminopyrine, a new adulterant, was identified and quantified only in cocaine base samples, mainly as a trace adulterant but also as a major compound. In most samples adulterated with aminopyrine, phenacetin was also identified as a major adulterant, suggesting a possible association of the two pharmaceuticals in the cutting process. Aminopyrine was not detected in 2010 seizures, but became a common adulterant throughout the years of 2011 to 2013. A mass balance approach analysis also established that adulterants are responsible for only 12% of the mass of all seizures (i.e., 84 kg), whereas 77% (i.e., 553 kg) is due to alkaloids (cocaine and cis/trans-cinnamoylcocaine), contributing to provide forensic intelligence information to police investigators.
DOI: 10.6084/m9.figshare.14303794.v1
title: TiO2 Supported on HZSM-11 Zeolite as Efficient Catalyst for the Photodegradation of Chlorobenzoic Acids

description: The photocatalytic decomposition of 2-, 3- and 4-chlorobenzoic acids (2CB, 3CB and 4CB, respectively) with TiO2 loaded on HZSM-11 zeolite was investigated. The optimum decomposition rate of 2CB was obtained with TiO2/HZSM-11(30%) (TiO2 30 wt.%) catalyst at a concentration of 1 mg mL-1. 2CB and 3CB decompose at similar rates, but 4CB remains adsorbed on TiO2/HZSM-11(30%) without further degradation. This absorption is attributed to the relative positions of Cl and COOH groups on 4CB. However, this compound can be partially degraded and/or removed from aqueous solutions by TiO2/HZSM-11(50%) catalyst or HZSM-11 zeolite. TiO2/HZSM-11(30%) is stable; it retains its photocatalytic properties after nine cycles, can be easily removed and immediately reused. These are important advantages of TiO2/HZSM-11(30%) over unsupported TiO2, making it a good photocatalyst for the treatment of polluted water. On the other hand, HZSM-11 could be used to selectively adsorb 4CB, thus becoming an alternative method of environmental remediation.
DOI: 10.6084/m9.figshare.14303789.v1
title: The Multiple Faces of Eugenol. A Versatile Starting Material and Building Block for Organic and Bio-Organic Synthesis and a Convenient Precursor Toward Bio-Based Fine Chemicals

description: Phenylpropenes are produced by plants as part of their defense strategy against microorganisms and animals, and also as floral attractants of pollinators. Eugenol, the main component of clove’s essential oil, is an inexpensive and easily available phenylpropene that has been known by humankind since antiquity, and used as a medicinal agent, but also for food flavoring and preservation. The review includes the most relevant results obtained during the last 15 years with regard to the synthetic uses of eugenol. Discussed here are the multiple applications of eugenol in organic synthesis, including its use as starting material or building block for the total synthesis of natural products, their analogs and derivatives, as well as other structurally interesting or bioactive compounds. The preparation technologically relevant macrocycles and polymeric derivatives of eugenol, is included, and the impact of biotechnology on the use of eugenol as feedstock for biotransformations, leading to other valuable small molecules is also addressed.
DOI: 10.6084/m9.figshare.14303786.v1
title: Synthesis of Nano-Pore Size Ag(I)-Imprinted Polymer for the Extraction and Preconcentration of Silver Ions Followed by Its Determination with Flame Atomic Absorption Spectrometry and Spectrophotometry Using Localized Surface Plasmon Resonance Peak of Silver Nanoparticles

description: Silver ion imprinted polymer (IIP) was synthesized in the presence of Ag(I)-N,N’‑bis(salicylidene)ethylenediamine (salen) complex using 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, and 2,2-azobis(isobutyronitrile) (AIBN) as the initiator. The Ag(I)-imprinted polymer (IIP) particles were characterized by SEM (scanning electron microscope), FTIR (Fourier transform infrared spectroscopy) and BET/BJH (Brunauer-Emmett-Teller/Barrett-Joyner-Halenda) analysis. The imprinted Ag(I) ions were completely removed by leaching the IIP with thiourea (0.5 mol L-1). The polymer was employed as a selective sorbent for extraction and separation of the trace amounts of the Ag(I) ions. The preconcentrated ion was determined via the flame atomic absorption spectrometry (FAAS) or it was reduced to silver nanoparticles and quantified by spectrophotometry based on its localized surface plasmon resonance peak (LSPRP). The figures of merit of both methods were compared. Under the optimized conditions, a sample volume of 80 mL resulted in an enhancement factor of 312. The detection limit (3Sb/m) and the relative standard deviation (n = 10) at 10 µg L-1 level for FAAS were found to be 0.06 µg L-1, 2.9%, whereas for the LSPRP method they were 0.5 µg L-1 and 10.3%, respectively. The methods were successfully applied to the determination of silver in radiology film, hair, nails, and water samples.
DOI: 10.6084/m9.figshare.14303784.v1
title: Straightforward and Clean Ultrasound-Promoted Synthesis of 2-(4,5-Dihydro‑1H‑pyrazol-1-yl)pyrimidines

description: A series of twelve novel 2-(pyrazol-1-yl)pyrimidine derivatives was easily obtained under ultrasonic conditions by the cyclocondensation reaction of 1-carboxamidino-pyrazoles with 4-methoxyvinyl-trifluoromethyl ketones using ethanol as an environment-friendly solvent in the presence of potassium hydroxide. Comparison of the ultrasound-promoted reaction with classical methodology shows that the former is faster and gives better yield. The products were isolated in excellent purity grades without purification by chromatography or recrystalization.
DOI: 10.6084/m9.figshare.14303783.v1
title: Novel and Fast Microwave-Assisted Synthesis of Carbon Quantum Dots from Raw Cashew Gum

description: Carbon quantum dots (C-dots) with average size of 9 nm were synthesized from an aqueous solution of raw cashew gum (RCG) using a novel and fast microwave-assisted technique which involves two steps. In the first step (partial depolymerization in solution) some monomer units are formed through the autohydrolysis of CG and a small amount of 5-hydroxymethyl furfural can be obtained. The second step involves polycondensation/polymerization to give rise to a polyfuranic structure followed by aromatization/carbonization and nuclear burst. At the end of the process a composite of partially depolymerized CG and C-dot was formed. A mechanism involved in microwave-assisted two-steps synthesis was suggested. Although no passivation reagent was used, an intensely blue photoluminescent material in UV light was obtained. C-dot was characterized by spectroscopy in the medium infrared, thermal analysis, gel permeation chromatography, transmission electron microscopy, zeta potential, and photoluminescence.
DOI: 10.6084/m9.figshare.14303780.v1
title: Recovery Process Development for the Rare Earths from Permanent Magnet Scraps Leach Liquors

description: The current study deals with the recovery process development for the rare earths (REs), i.e., dysprosium (Dy) and neodymium (Nd), metals from permanent magnet scraps leach liquors. Its main objective is the recovery of the rare earths (Dy and Nd) from permanent magnet scraps (PMSs). Introdutory experiments were carried out to get leach liquor solution: oxidation/roasting, acid leaching, and precipitation methods implemented for PMSs dissolution. The obtained PMSs leach liquor was diluted ten times and used for present study. Di-2-ethylhexyl phosphoric acid (D2EHPA) was used as an extractant for recovery of the REs and kerosene as diluent system. The present study optimized the various experimental parameters such as the time influence on extraction process, influence of pH, extractant concentration, separation factors calculated, scrubbing, stripping, maximum loading capacity of the extractant, and various phase ratios as well as phase ratios influence on present metals separations. Loading capacity of D2EHPA and selective stripping process were developed for targeted metal ions by using various mineral acids such as hydrochloric, sulfuric and nitric acids. The metal content analysis in the aqueous samples was determined with inductively coupled plasma optical emission spectrometer (ICP OES) for sensitive and accurate data.