Carbon Microspheres as Supercapacitors Kim, Ho; Fortunato, Maria E; Xu, Hangxun ...
Journal of physical chemistry. C,
10/2011, Volume:
115, Issue:
42
Journal Article
Peer reviewed
Carbon microstructures fabricated by ultrasonic spray pyrolysis (USP) of aqueous precursors were tested as supercapacitors. USP carbons (USP-C) possess unique physicochemical characteristics, ...including substantial microporosity and high surface concentrations of oxygenated functional groups. We find that USP-Cs have higher electrochemical double-layer capacitance compared with other carbon structures. Porous carbon microspheres prepared from USP of lithium dichloroacetate, lithium/potassium propiolate, or sucrose produce electrochemical double layer capacitors (EDLCs) that have gravimetric capacitances of 185, 341, and 360 F/g, respectively. Microstructural and chemical analyses of the carbon materials suggest that the observed capacitance is related to the effects of surface functionality.
Porous carbon microspheres impregnated with iron-based nanoparticles are prepared in a single step, continuous process using ultrasonic spray pyrolysis (USP).
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► Iron-impregnated ...carbon was prepared using ultrasonic spray pyrolysis. ► Synthesis performed using a continuous flow process with only a single heating step. ► Carbonization, porosity development, and metal impregnation occurred simultaneously. ► Materials were impregnated with reduced iron oxides, including magnetite and wustite. ► Surface areas were as high as 800
m
2/g with bulk Fe content as high as 35
wt.%.
Porous carbon microspheres impregnated with iron-based nanoparticles are prepared in a single step, continuous process using ultrasonic spray pyrolysis (USP). Precursor solutions containing a carbon source, an inorganic salt, and an iron salt are ultrasonically aerosolized and pyrolyzed. Solutions containing nitrate or chloride salts are examined. During pyrolysis, sucrose is dehydrated to carbon, and the metal salt is converted to crystalline or non-crystalline iron species, depending on processing conditions. The product’s porosity is generated from: (1) aromatization of carbon around an
in situ template, (2)
in situ gasification of isolated carbon, or (3)
in situ chemical activation of the carbon precursor. Porous carbon spheres (0.5–3
μm diameter) containing well-dispersed iron oxide nanoparticles (4–90
nm diameter), referred to here as Fe–C, are prepared. Iron loadings between 1 and 35
wt.% are achieved while maintaining well-dispersed Fe nanoparticles with as-produced surface areas up to 800
m
2/g. Post-pyrolysis heat and hydrogen treatments increase the surface area of the materials while reducing iron species. USP Fe–C materials may have useful catalytic applications due to their potential for high-loading of well-dispersed metal nanoparticles. Despite negligible surface Fe content, chromium reduction tests indicate that internal Fe sites are catalytically active.
A previously isolated indigenous strain of
Pseudomonas
sp. was used to treat effluents, a synthetic and an industrial-containing benzalkonium chloride (BAC), in continuous upflow biofilm aerobic ...reactors. The reactor used to treat the synthetic effluent was constructed from Plexiglas® and filled with hollow polyvinyl chloride (PVC) cylinders as support material, whereas the one used to treat the industrial effluent was constructed from PVC and had a high recirculation flow rate and lightweight expanded clay aggregate (LECA®) as support material. Biodegradation was evaluated by spectrophotometry, HPLC, and microbial growth. Detoxification was evaluated by using
Vibrio fisheri
,
Pseudokirchneriella subcapitata
, and
Lactuca sativa
as test organisms. Maximal BAC influent concentrations were of 383.4 and 1172.0 mg L
−1
respectively, which corresponds to a maximal organic load of 49.8 and 146.5 g BAC m
−3
day
−1
. The efficiency of the reactors was higher than 99.3% in terms of compound removal and 97.0% in terms of COD removal. Complete detoxification of the effluent was demonstrated for the synthetic effluent, whereas a toxicity removal higher than 97% was reached in the case of the industrial effluent. The promising behavior of the isolated indigenous strain to degrade BAC in continuous reactors allows us to suggest its possible use in remediation processes.
A spectral and haunting figure, Oswald Spengler, with his main work (The Decline of the West) reappears on the scene every time the present is experienced as a moment of crisis or political, ...ideological, cultural transition. Even in our own time, there are references, researches, and articles that, although in different ways, all seem to be connected by a worried regard for his diagnoses. In the two parts of this study, is made an attempt to show, however, why Spengler cannot be evoked (or dismissed) as the anti-West. Rather, it is a matter of pointing out how the mimetic blurring with the positions of the alleged prophet of doom, in the name of the West's self-love and its exceptionalism, risks confirming the prognosis of the decline, testifying to the misery, or impotence, of the critique aimed at opposing its fulfilment.
Water from six points from the Riachuelo-Matanza basin was analyzed in order to assess ibuprofen biodegradability. In four of them biodegradation of ibuprofen was proved and degrading bacterial ...communities were isolated. Biodegradation in each point could not be correlated with sewage pollution. The indigenous bacterial community isolated from the point localized in the La Noria Bridge showed the highest degradative capacity and was selected to perform batch and continuous degradation assays. The partial 16S rRNA gene sequence showed that the community consisted of Comamonas aquatica and Bacillus sp. In batch assays the community was capable of degrading 100 mg L
−1
of ibuprofen in 33 h, with a specific growth rate (μ) of 0.21 h
−1
. The removal of the compound, as determined by High performance liquid chromatography (HPLC), exceeded 99% of the initial concentration, with a 92.3% removal of Chemical Oxygen Demand (COD). In a down-flow fixed-bed continuous reactor, the community shows a removal efficiency of 95.9% of ibuprofen and 92.3% of COD for an average inlet concentration of 110.4 mg. The reactor was kept in operation for 70 days. The maximal removal rate for the compound was 17.4 g m
−3
d
−1
. Scanning electron microscopy was employed to observe biofilm development in the reactor. The ability of the isolated indigenous community can be exploited to improve the treatment of wastewaters containing ibuprofen.
Objective: to translate and culturally adapt the Risk assessment and management of exposure of health care workers in the context of covid-19 questionnaire to the Brazilian context and to develop and ...evaluate a sociodemographic and occupational characterization questionnaire to compose the adapted questionnaire. Method: five stages were conducted to adapt the Risk assessment and management of exposure of health care workers in the context of covid-19 questionnaire, namely: translation, synthesis of the translations, evaluation by a committee of judges, back translation and pre-test. As for the complementary questionnaire, it was elaborated and evaluated by a committee of judges and a pre-test was carried out. Results: the questionnaires were validated and the pre-test stage was conducted with health workers and students. Conclusion: the final version adapted to the Brazilian context was called Questionário de avaliação de risco e gestão da exposição de trabalhadores e estudantes de saúde no contexto da covid-19 and is available for use, together with the final version of the Sociodemographic and occupational questionnaire: Risk assessment and management of exposure of health care workers and students in the context of covid-19. These questionnaires may assist in mitigating the risks of infection, illness and death of health workers and students due to covid-19.
Objetivo: traduzir e adaptar culturalmente o questionário Risk assessment and management of exposure of health care workers in the context of covid-19 para o contexto brasileiro e elaborar e avaliar um questionário de caracterização sociodemográfica e ocupacional para compor o questionário adaptado. Método: cinco etapas foram realizadas para adaptação do questionário Risk assessment and management of exposure of health care workers in the context of covid-19: tradução, síntese das traduções, avaliação por comitê de juízes, retrotradução e pré-teste. Quanto ao questionário complementar, foi construído e avaliado por um comitê de juízes e realizado pré-teste. Resultados: os questionários foram validados e a etapa de pré-teste foi realizada com trabalhadores e estudantes da área de saúde. Conclusão: a versão final adaptada para o contexto brasileiro foi denominada Questionário de avaliação de risco e gestão da exposição de trabalhadores e estudantes de saúde no contexto da covid-19 e está disponibilizada para uso, juntamente com a versão final do questionário sociodemográfico e ocupacional: avaliação de risco e gestão da exposição de trabalhadores e estudantes da área de saúde no contexto da covid-19. Estes questionários podem auxiliar na mitigação dos riscos de infecção, adoecimento e morte de trabalhadores e estudantes da área de saúde pela covid-19.
Objetivo: traducir y adaptar culturalmente el cuestionario Risk assessment and management of exposure of health care workers in the context of covid-19 al contexto brasileño y elaborar y evaluar un cuestionario de caracterización sociodemográfica y ocupacional para formular el cuestionario adaptado. Método: se llevaron a cabo cinco pasos para adaptar el cuestionario Risk assessment and management of exposure of health care workers in the context of covid-19: traducción, síntesis de traducciones, evaluación por un comité de jueces, retrotraducción y pretest. En cuanto al cuestionario complementario, fue elaborado y evaluado por un comité de jueces y se realizó una prueba previa. Resultados: se validaron los cuestionarios y se realizó la etapa de pretest con trabajadores y estudiantes del área de la salud. Conclusión: la versión final adaptada al contexto brasileño se denominó Questionário de avaliação de risco e gestão da exposição de trabalhadores e estudantes de saúde no contexto da covid-19 y está disponible para su uso, junto con la versión final del Questionário de avaliação de risco e gestão da exposição de trabalhadores e estudantes de saúde no contexto da COVID-19. Estos cuestionarios pueden ayudar a disminuir los riesgos de infección, enfermedad y muerte de los trabajadores y los estudiantes del área de la salud por covid-19.
Fresh vegetables and shellfish are prone to microbial contamination through irrigation or breeding with sewage-polluted waters, as well as by infected food handlers. In this work, we studied the ...presence of human and bovine polyomaviruses and human norovirus in fresh lettuces, strawberries and oysters produced in Buenos Aires province, Argentina. In oysters, we also investigated F-specific RNA bacteriophages, indicator
Escherichia coli
(
E. coli
) and pathogen bacteria of concern (
Salmonella
spp.,
Vibrio
spp.). Within vegetables, we found viral contamination of human origin given the presence of human-associated polyomaviruses -MCPyV, HPyV6, JCPyV, and SV40- in lettuce and strawberry samples (16 and 10%, respectively), probably coming from irrigation waters and food handling. Among oysters, human (MCPyV, 4.2%) and bovine (BPyV1, 8.4%) polyomaviruses were detected even with low counts of
E. coli.
Bacteriophages (
n
= 3) and
Salmonella
spp
.
(
n
= 1) were also found, while
Vibrio
spp. was not detected. These results may indicate that the contamination in oysters comes from human and animal excreta, probably present in breeding waters. Norovirus was not detected in any food sample. To our knowledge, this is the first description of SV40 in lettuces and MCPyV and BPyV1 in oysters. The detection of different viral contaminants encourages further studies to evaluate the need for including viral indicators in microbiological standards. The identification of possible sources and routes of contamination using viral markers during routine microbiological controls, such as the polyomaviruses used in this work, would be useful to focus attention on the most hazardous stages of the food production chain.
The presence of nitrate in sources of drinking water is a matter of concern because of its potential risk for human health. In many countries like Argentina, an increasing proportion of the ...population chooses to consume bottled water, among other reasons, for lack of water access. The present study was conducted (a) to evaluate the quality of bottled waters by determining nitrate concentration, (b) to relate bottled water quality with water access, (c) to analyze public awareness about bottled water quality and consumption habits of the population in the urban area of Buenos Aires. Two locations were selected, Ciudad Autónoma de Buenos Aires (C.A.B.A.) and Malvinas Argentinas in Buenos Aires Province (PBA), with percentages of water access of 99.6% and 8.8%, respectively. Random samples from both locations (n = 100) were analyzed. A survey was conducted in order to inquire about perception of population on bottled water quality and their consumption habits. In C.A.B.A., no sample exceeded the 45 mg/L limit value in force in Argentina, while in Malvinas Argentinas, 34% of the brands analyzed showed values above it. The survey revealed that 71.7% of people consume bottled water. While people in C.A.B.A. do so mainly out of habit, safety is the priority in PBA.
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