551 research outputs found
Catalytic conversion of caffeine into molecules of valuable interest via N-demethylation reaction
This work aims to apply catalytic processes to promote the conversion of caffeine into valuable dimethylxanthines via N-demethylation reaction. Thus, we seek to evaluate the products formed and propose the reactions involved and their mechanisms. Reaction conditions were evaluated including different concentrations of Fenton reagent and ascorbic acid to evaluate caffeine oxidation. Theobromine, paraxanthine, and theophylline formation was proven by HPLC-DAD and mass spectrometry analysis evidencing the N-demethylation reactions, via radicals, with about 1 % yield. These results open the way for new N-demethylation reaction routes to be studied with applications for caffeine and other biomolecules in diverse areas such as biochemistry and medicinal chemistry.
Application of the Fenton catalysis as alternative to promote the conversion of caffeine in other xanthines by N-demethylation. In this scenario was verified the capability of ascorbic acid in promoting same reaction, both environmentally friendly processes. This work investigates the possibility of using a well known biocompound as a precursor to obtain value added molecules.This study was financially supported by the Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) –
Finance Code 001 and by CIMO (UIDB/00690/2020) through
FEDER under Program PT2020. In addition, the authors acknowledge
Central de Análise e Prospecção Química – CAPQ and
Laboratório Central de Biologia Molecular (LCBM), Chemistry
Department/UFLA for their technical support. Jose L. Diaz De
Tuesta acknowledges the financial support through the program
of Atracción al Talento of Comunidad de Madrid (Spain) for
the individual research grant 2022-T1/AMB-23946.info:eu-repo/semantics/publishedVersio
Kinetic insights on wet peroxide oxidation of caffeine using EDTA-functionalized low-cost catalysts prepared from compost generated in municipal solid waste treatment facilities
Nowadays, sorted organic fraction of municipal solid waste is typically treated by
anaerobic digestion processes, resulting therein a solid stream, further processed to
obtain compost, whose production is higher than the existing demand as fertilizer.
The current work proposes an alternative strategy for the recovering of compost
through the production of low-cost catalysts by calcination (1073 K) and sulfuric acid
treatments, followed by sequential functionalization with tetraethyl orthosilicate (TEOS)
and ethylenediamine tetraacetic acid (EDTA). Activity and stability of the catalysts are
assessed in the wet peroxide oxidation of synthetic wastewater effluents contaminated
with caffeine, a model micro-pollutant, achieving its complete removal after 6 h at 353–
383 K and catalyst loads of 0.5–2.5 g L−1. The increase of the catalytic activity of the
materials upon functionalization with TEOS and EDTA is demonstrated and a kinetic
modeling of caffeine degradation and hydrogen peroxide consumption with the best
catalyst is assessed by pseudo-first power-law rate equations.This work was financially supported by project ‘‘VALORCOMP - Valorización de compost y otros desechos procedentes de la fracción orgánica de los residuos municipales’’, 0119_VALORCOMP_2_P, through FEDER under Program INTERREG; and CIMO (UIDB/00690/2020) through FEDER under Program PT2020.info:eu-repo/semantics/publishedVersio
Application of catalysts developed from compost derived from municipal solid waste in the removal of caffeine by wet peroxide oxidation
Nowadays, waste management through mechanical biological treatment (MBT) consists
on the use of the separated organic fraction of municipal solid waste (MSW) to feed anaerobic
digestion processes, resulting therein a solid stream, further processed to compost, which can
be used as fertilizer. Currently, the production of compost from MBT is higher than the existing
demand, and the expected developments on up-coming directives ruling “End-of-waste” criteria
are leading to barriers on the use of waste-derived fertilizers (European Commision, 2013). In
this context, the current work proposes an alternative strategy to the valorisation of compost,
through the production of low-cost materials to be applied in the catalytic wet peroxide
oxidation (CWPO) of synthetic wastewater effluents contaminated with caffeine, used as a
model pollutant of emerging concern. Caffeine is the most consumed psychoactive drug
worldwide. It is one of the components of painkillers, medication against migraine, fatigue,
drowsiness and breathing problems. Its consumption is also associated with an overall lower
risk of malignant growth like hepatocellular, endometrial or colorectal cancer (Ganzenko et al.,
2015). However, the effect of caffeine and its environmental degradation products on aquatic
living species is not properly known. Caffeine, is a world wide consumed psychoactive drug,
in a way that becomes a persistent compound and cannot be efficiently removed by municipal
wastewater treatment facilities (Ganzenko et al., 2015). As a consequence, caffeine and its
metabolites are present in the effluents of wastewater treatment plants (Gracia-Lor et al., 2017).This work was financially supported by project “VALORCOMP -
Valorización de compost y otros desechos procedentes de la fracción orgánica de los residuos
municipales”, 0119_VALORCOMP_2_P, and project “AIProcMat@N2020 - Advanced
Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020”,
reference NORTE-01-0145-FEDER-000006, supported by NORTE 2020, under the Portugal
2020 Partnership Agreement, through FEDER, and Project Associate Laboratory LSRE-LCM
- UID/EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC).info:eu-repo/semantics/publishedVersio
Cyanobacterial diversity in microbial mats from the hypersaline lagoon system of Araruama, Brazil: An in-depth polyphasic study
Microbial mats are complex, micro-scale ecosystems that can be found in a wide range of environments. In the top layer of photosynthetic mats from hypersaline environments, a large diversity of cyanobacteria typically predominates. With the aim of strengthening the knowledge on the cyanobacterial diversity present in the coastal lagoon system of Araruama (state of Rio de Janeiro, Brazil), we have characterized three mat samples by means of a polyphasic approach. We have used morphological and molecular data obtained by culture-dependent and -independent methods. Moreover, we have compared different classification methodologies and discussed the outcomes, challenges, and pitfalls of these methods. Overall, we show that Araruama's lagoons harbor a high cyanobacterial diversity. Thirty-six unique morphospecies could be differentiated, which increases by more than 15% the number of morphospecies and genera already reported for the entire Araruama system. Morphology-based data were compared with the 16S rRNA gene phylogeny derived from isolate sequences and environmental sequences obtained by PCR-DGGE and pyrosequencing. Most of the 48 phylotypes could be associated with the observed morphospecies at the order level. More than one third of the sequences demonstrated to be closely affiliated (best BLAST hit results of ≥99%) with cyanobacteria from ecologically similar habitats. Some sequences had no close relatives in the public databases, including one from an isolate, being placed as "loner" sequences within different orders. This hints at hidden cyanobacterial diversity in the mats of the Araruama system, while reinforcing the relevance of using complementary approaches to study cyanobacterial diversity. © 2017 Ramos, Castelo-Branco, Leão, Martins, Carvalhal-Gomes, Sobrinho da Silva, Mendonça Filho and Vasconcelos.This work was supported by the Biogeochemical Project
(AMPETRO 14777—Cooperation term 0050.0023165.06.4)
of the GSE (Sedimentology Management) Network of
PETROBRAS, by the Brazilian National Research Agency—
CNPq and by the Research Agency of Rio de Janeiro
State—FAPERJ. It was also funded by Portuguese National
Funds through FCT—Fundação para a Ciência e a Tecnologia,
grants SFRH/BD/80153/2011 to VR, IF/01358/2014 to PL,
and UID/Multi/04423/2013 and by the Structured Program of
R&D&I INNOVMAR—Innovation and Sustainability in the
Management and Exploitation of Marine Resources (reference
NORTE-01-0145-FEDER-000035, Research Line NOVELMAR),
funded by the Northern Regional Operational Program
(NORTE2020) through the European Regional Development
Fund (ERDF)
MELHORIA NA EFICIÊNCIA DA CLARIFICAÇÃO DE SUCO DE MARACUJÁ PELA COMBINAÇÃO DOS PROCESSOS DE MICROFILTRAÇÃO E ENZIMÁTICO
Este trabalho teve como objetivo a obtenção de suco
clarificado de maracujá, utilizando a técnica de
microfiltração. Introduziu-se a etapa de tratamento
enzimático antes da microfiltração, visando aumentar
a eficiência do processo pela redução da viscosidade
e do teor de polpa do suco. Foram testadas três
diferentes enzimas hidrolíticas em três níveis de
concentração. Os resultados não mostraram
diferenças significativas quanto ao Brix, pH e acidez
das amostras de suco hidrolisado em relação ao suco
integral. Observou-se efeito positivo da ação das
enzimas na redução da viscosidade e do teor de polpa.
A microfiltração foi realizada em sistema de membrana
tubular com tamanho médio de poro equivalente a
0,3 µm e pressão transmembrana de 1,5 bar. O suco
permeado apresentou-se límpido, isento de polpa e com
qualidade e sanidade microbiológica. Tais resultados
comprovaram a eficiência da microfiltração para
clarificação e estabilização de sucos de frutas.
IMPROVEMENT IN THE EFFICIENCY OF PASSION FRUIT JUICE
CLARIFICATION BY THE COMBINATION OF MICROFILTRATION AND
ENZYMATIC PROCESSES
Abstract
This work had as objective the obtention of clarified passion fruit juice by using the
microfiltration technique. A step of enzymatic treatment was introduced before
microfiltration, aiming to enhance process efficiency by reduction of viscosity and
pulp content of the juice. Three different hidrolytic enzymes were tested in three
concentration levels. The results didnt demonstrate significant differences in Brix,
pH and acidity of the hidrolyzed juice samples in relation to the concentrated juice.
Positive effect was observed in the action of the enzymes in the reduction of
viscosity and pulp content. The microfiltration was realized in a tubular membrane
system with average size of the pore equivalent to 0.3 m and transmembrane
pressure of 1.5 bar. The permeate juice was clear, free from pulp and with good
micribiological quality. Such results proved the efficiency of microfiltration for
clarification and stabilization of fruit juices
Scattering theory and ground-state energy of Dirac fermions in graphene with two Coulomb impurities
We study the physics of Dirac fermions in a gapped graphene monolayer containing two Coulomb impurities. For the case of equal impurity charges, we discuss the ground-state energy using the linear combination of atomic orbitals (LCAO) approach. For opposite charges of the Coulomb centers, an electric dipole potential results at large distances. We provide a nonperturbative analysis of the corresponding low-energy scattering problem
Deficiências de kacronutrientes e de boro em seringueira (Hevea brasiliensis L.)
In order to obtain: a) a clear picture of the deficiencies symptoms of N, P, K, Ca, Mg, S and B; b) the lack of the elements on the dry matter production; c) concentration of the macro and micronutrients on the leaves, stems and roots. Young rubber plants (Hevea brasiliensis L.), were cultivated in nutrients solutions, in which one the following elements were omitted at once: N, P, K, Ca, Mg, S and B. Clear out symptoms were obtained for all macronutrients and boron. The growth rate of the rubber plants were drastically affected by lack of N, K followed by other nutrients. The omission of P from the nutrient solution did not affected the growth of the plants. The levels detected by chemical analysis of the leaves from with symptoms of deficiency and without symptoms of deficiency plants were: N% = 1.94 and 3.40: P% =0.14 and 0.25; K% = 0.79 and 2.22; Ca% = 0.59 and 1.28; Mg% = 0.26 and 0.50; S% = 0.10 and 0.10; B ppm = 31-3 and 171.8.Plantas de seringueira (Hevea brasiliensis L.) foram cultivadas em casa de vegetação, em quartzo moído, irrigado com soluções nutritivas, e submetidas aos seguintes tratamentos: completo, omissão de N, omissão de P, omissão de Ca, omissão de Mg, omissão de S e omissão de B, com o objetivo de: (a) obter sintomas de deficiências de macronutrientes e de boro; (b) analisar o crescimento das plantas através da produção de matéria seca; (c) determinar a concentração de macro e micronutrientes nas folhas, caule e raízes das plantas cultivadas nos diversos tratamentos. Os sintomas visuais de deficiência foram identificados e descritos. As plantas foram coletadas e separadas em raiz, caule e folhas, e determinaram-se os teores de macro e micronutrientes . Os resultados mostraram: - foram identificados sintomas de deficiências para todos os tratamentos com omissão de nutrientes (N, P, K, Ca, Mg, S e B); - a omissão de N, K, Mg ou B da solução nutritiva diminuiu o crescimento das plantas; - as concentrações dos elementos nas folhas de plantas com sintomas e sem sintomas de deficiência foram, respectivamente: N% = 1,94 e 3,40; P% = 0,14 e 0,25; K% = 0,79 e 2,22; Ca% = 0,59e 1,28; Mg% = 0,26 e 0,50; S% = 0,10 e 0,10; Bppm = 31 ,3 e 171,8
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