Adsorption of BTX (benzene, toluene, o-xylene, and p-xylene) from aqueous solutions by modified periodic mesoporous organosilica

AbstractThe capacity of a periodic mesoporous organosilica (PMO) to adsorb the aromatic compounds benzene, toluene, o-, and p-xylenes (BTX), which are usually present in produced waters, was investigated under both column and batch processes. The PMO was synthesized by condensation of 1,4 bis(triethoxisilyl)benzene (BTEB) under acidic conditions by using structure-directing agent (SDA) Pluronic P123 in the presence of KCl. Thermogravimetric analysis showed that the presence of the surfactant decreases the thermal stability of the PMO. The small-angle X-ray diffraction pattern, as well as the nitrogen adsorption/desorption isotherm measurements, revealed that the synthesized material has a crystalline structure, with hexagonally-ordered cylindrical mesopores. The adsorption kinetics study indicated an adsorption equilibrium time of 50min and also showed that the data best fitted the pseudo-first order kinetic model. The intraparticle diffusion model was also tested and pointed to the occurrence of such process in all cases. Both Langmuir and Temkin models best represented the adsorption isotherms of toluene; Langmuir and Redlich–Peterson models best represented the data obtained for the other compounds. Adsorption capacity decreases in the order benzene>o-xylene>p-xylene>toluene. Satisfactory results were observed in the application of the synthesized PMO for the removal of BTX from aqueous solution

Dynamic blockage of drippers as a function of the application of super simple phosphate and nítric acid in localized irrigation

O superfosfato simples (SS) é uma alternativa aos adubos fosfatados que são utilizados via fertirrigação, como o ácido fosfórico, que provoca acidificação do bulbo úmido no solo, e o monofosfato de amônio purificado, que apresenta maior preço. No entanto, não se conhece o efeito de tal adubo no funcionamento de emissores, principalmente nos gotejadores, nem se é possível controlar o entupimento por SS por meio de aplicações de ácido. Assim, desenvolveu-se este trabalho com o objetivo de avaliar a possibilidade da utilização do superfosfato simples via gotejamento, como alternativa ao uso de outros adubos fosfatados, e a tentativa de controle do entupimento utilizando ácido nítrico. O trabalho foi desenvolvido em bancada de ensaios de gotejadores, localizada no Laboratório de Hidráulica da ESALQ/USP. Foram aplicadas doses de 50; 75 e 100% da solubilidade do superfosfato simples (SS), em 26 tubogotejadores de diferentes marcas comerciais, e ao fim de 360 horas de irrigação, foi aplicado ácido nítrico com pH 2, na tentativa de desentupir os gotejadores mais sensíveis. Diante dos resultados, foi possível inferir que o uso do superfosfato simples pode ser feito via fertirrigação, e o ácido nítrico, aplicado segundo esta metodologia, não proporcionou a desobstrução dos emissores.The super simple phosphate (SS) is an alternative to the phosphorous fertilizers which are used through fertigation, as the phosphoric acid, which triggers acidification of the wetted volume in the soil, and the monophosfato of purified ammonium, that has a higher price. However, the effect of such fertilizer in the emitters function, mainly in the drippers, is not known neither if it is possible to control the blockage for SS through acid applications. Thus, this study was developed in order to evaluate the possibility of the use of super simple phosphate trough drip irrigation, as an alternative to the use of other phosphorous fertilizers, and the attempt of controlling the blockage with nitric acid. The work was carried out in bench of drippers rehearsals, located at the Hydraulic laboratory in ESALQ-USP. Doses of 50; 75 and 100% of the super simple phosphate (SS) were applied in 26 emitter tubes with different commercial marks, and after 360 hours the nitric acid with a pH of 2 was applied, in the attempt of clearing the most sensitive drippers to the blockage. With the results it was possible to infer that: the use of super simple phosphate can be done by fertigation without causing damages to the system and the nitric acid, applied according to this methodology, did not provide the clearance of the emitters

Crises social sensing: Longitudinal monitoring of social perceptions of systemic risk during public health crisis

Monitoring how different people – as ‘social sensors’ – evaluate and respond to crisis such as pandemics, allows tailoring crisis communication to the social perceptions of the situation, at different moments. To gather such evidence, we proposed a index of social perceptions of systemic risk (SPSR), as an indicator of a situational threat compromising risks to physical health, psychological health, the economy, social relations, health system, and others. This indicator was the core of a social sensing approach applied to crisis situations, implemented during the COVID-19 pandemic through a content analysis of more than 130.000 public comments from Facebook™ users, in COVID-19 related publications. This content coding allowed creating a SPSR index monitored during a one-year descriptive longitudinal analysis. This index correlated with co-occurring events within the social system, namely epidemiological indicators across measurement cycles (e.g. new deaths; cumulative number of infection cases; Intensive Care Unit hospitalizations) and tended to reflect the epidemiological situation severity (e.g. with the highest level registered during the worst pandemic wave). However, discrepancies also occurred, with high SPSR registered in a low severity situation, i.e. low number of hospitalizations and deaths (e.g. school year beginning), or low SPSR in a high severity situation (e.g. 2nd pandemic wave during Christmas), showing other factors beyond the epidemiological situation contributing to the social perceptions. After each ‘crisis period’ with SPSR peaking, there was a ‘restoration period’, consistently decreasing towards average levels of the previous measurement cycle. This can either indicate social resilience (recovery and resources potentiation) or risk attenuation after a high-severity period. This study serves as preliminary proof of concept of a crises social sensing approach, enabling monitoring of social system dynamics for various crisis types, such as health crisis or the climate crisis.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

Symbolic powers of monomial ideals and Cohen-Macaulay vertex-weighted digraphs

In this paper we study irreducible representations and symbolic Rees algebras of monomial ideals. Then we examine edge ideals associated to vertex-weighted oriented graphs. These are digraphs having no oriented cycles of length two with weights on the vertices. For a monomial ideal with no embedded primes we classify the normality of its symbolic Rees algebra in terms of its primary components. If the primary components of a monomial ideal are normal, we present a simple procedure to compute its symbolic Rees algebra using Hilbert bases, and give necessary and sufficient conditions for the equality between its ordinary and symbolic powers. We give an effective characterization of the Cohen--Macaulay vertex-weighted oriented forests. For edge ideals of transitive weighted oriented graphs we show that Alexander duality holds. It is shown that edge ideals of weighted acyclic tournaments are Cohen--Macaulay and satisfy Alexander dualityComment: Special volume dedicated to Professor Antonio Campillo, Springer, to appea

Precipitation influence on the runoff of a small-watershed in the Federal District, Brazil

O conhecimento do escoamento superficial é importante para o dimensionamento de obras hidráulicas e para a conservação da água e do solo. O volume de água escoado superficialmente depende de fatores de natureza edafoclimática e fisiográfica da região. O objetivo deste estudo foi verificar a influência relativa do total precipitado (P), da precipitação antecedente (PA) e da intensidade de precipitação (IP) na ocorrência de eventos de escoamento superficial (Es), na microbacia do Córrego Capetinga, situada no Centro-Oeste do Brasil, região de cerrado. Foram analisados os dados de P, PA e IP obtidos durante seis anos hidrológicos, iniciando em 1º de julho de 1996 e terminando em 30 de junho 2002. Foram somente considerados valores de Es maiores ou iguais a 0,1 mm, oriundos de hidrógrafas geradas a partir dos dados de linígrafo instalado na saída da bacia. Um conjunto de 187 dados de P, PA, IP e Es foram submetidos à análise de regressão linear múltipla. Os resultados mostraram que as variáveis independentes P, PA e IP têm dupla e tríplice interação, influenciando na variável dependente Es. Por intermédio dos valores absolutos dos coeficientes de regressão, constatou-se que IP foi mais importante do que PA na estimativa da variável Es. O valor do coeficiente de escoamento superficial total médio sugere que a microbacia possui boas condições de infiltração de água no solo.The knowledge of surface runoff is important for adequate hydraulic structures designing and for soil water conservation. The total volume of water from surface runoff is dependent of local edaphic, climatic and physiographic conditions. The objective of this study was to find out the relative importance of rainfall amount (P) and intensity (IP) and antecedent precipitation (PA) on total runoff (Es) provided by the "Capetinga" stream watershed, located in Brazil mid-west savannah region. It was analyzed watershed data for a six years period beginning on July 1st, 1996, and ending on June 30th, 2002. It was considered only Es events greater or equal to 0.1 mm, measured with a stream gage located at the watershed outlet. A set of 187 P, PA, IP and Es events were submitted to a linear multiple regression analysis. The results showed that the independent variable P, PA and IP had two and three-factor interactions, influencing the dependent variable Es. Regression coefficients of absolute values evidenced that IP was more important than PA to estimate de independent variable Es. The average total runoff coefficient value suggests that the watershed has a good condition of soil water infiltration

Occurrence of fungi in rubber seeds

A cultura de seringueira (Hevea brasiliensis (Willd. ex-A Juss.) Muell. Agr.) no Brasil vem-se expandindo muito nos últimos anos e a sua multiplicação ocorre através de clones enxertados e de sementes. Dada a importância da cultura da seringueira no País e a limitada disponibilidade de referências bibliográficas de fungos transmitidos por suas sementes, desenvolveu-se este trabalho. As amostras de sementes de seringueira procedentes dos Estados do Pará e Bahia, no período de janeiro a junho de 1981, foram enviadas ao laboratório de Fitopatologia do Centro Nacional de Recursos Genéticos - CENARGEN - e submetidas aos seguintes testes de sanidade: método do papel de filtro, plaqueamento em ágar com dois tipos de exposições luminosas: luz negra e fluorescente, e exame direto. Dentre os fungos observados nas sementes de seringueira, diversos são conhecidos como patógenos deste hospedeiro, como é o caso do Colletotrichum gloeosporioides (Penz) Sacc., Phytophthora sp., Botryodiplodia sp, Phomopsis heveae (Petch) Boedijn, Dothiorella gregaria Sacc., Phyllosticta heveae (Zimm) e Alternaria sp. Os fungos saprófitos mais observados foram o Fumago sp. e o Aspergillus spp.The area under the rubber crop (Hevea brasiliensis (Willd ex-A. Juss.) Muell. Arg.) in Brazil has increased greatly in recent years and its multiplication is done through drafting clones and seeds. This work was carried out because the rubber crop is very important in the country and the bibliographical references to seed-borne fungi diseases is very limited. The rubber seed samples from Pará and Bahia states, in January to June of 1981, were examined in January to June 1981 at the Plant Pathology Laboratory of the National Center of Genetic Resources - CENARGEN. All of them underwent the following tests: blotter test, agar test, both with two kinds of lights: ultraviolet and fluorescent, and the direct examination test. Among many of fungi observed in the rubber seed are known as pathogens of rubber crop, such as: Colletotrichum gloeosporioides (Penz) Sacc, Phytophthora sp., Botryodiplodia sp, Phomopsis heveae (Petch) Boedijn, Dothiorella gregaria Sacc., Phyllosticta heveae Zimm., Alternaria sp. The raprophyte fungi which were most detected were Fumago sp. and Aspergillus spp

Secondary metabolites from the sponges Aplysina fistularis and Dysidea sp. and the antituberculosis activity of 11-ketofistularin-3

The present investigation reports the isolation of aeroplysinin-2, 2-(3,5-dibromo-4-methoxyphenyl)-N,N,N-trimethyletanamonium, 7,9-dibromo-10-hydroxy-8-methoxy-1-oxa-2-azaspiro[4.5]deca-2,6,8-trien-3-carboxylic acid and its methyl ester, 11-oxoaerothionin, aerothionin, 11-keto-12-hydroxyaerothionin, 11-ketofistularin-3 and fistularin-3 from Aplysina fistularis, as well as of furodysinin lactone and 9α,11α-epoxicholest-7-en-3β,5α,6α,10-tetrol-6-acetate from Dysidea sp. Although the extracts of both sponges displayed antituberculosis activity, only 11-ketofistularin-3 isolated from A. fistularis displayed antimycobacterial activity against Mycobacterium tuberculosis H34Rv, with MIC at 16 μg/mL and SI of 40, a result that reinforce that fistularin-3 derivatives are interesting leads for the development of antituberculosis drugs.American Society of Pharmacognosy FoundationFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)BIOTA/FAPESP - BIOprospecTAUSP - PIBIC/CNPqFAPES