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1.
Proc Biol Sci ; 290(2010): 20230957, 2023 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-37909073

RESUMO

Recent studies have suggested the presence of moonlight mediated behaviour in avian aerial insectivores, such as swifts. Here, we use the combined analysis of state-of-the-art activity logger data across three swift species, the common, pallid and alpine swifts, to quantify flight height and activity in responses to moonlight-driven crepuscular and nocturnal light conditions. Our results show a significant response in flight heights to moonlight illuminance for common and pallid swifts, i.e. when moon illuminance increased flight height also increased, while a moonlight-driven response is absent in alpine swifts. We show a weak relationship between night-time illuminance-driven responses and twilight ascending behaviour, suggesting a decoupling of both crepuscular and night-time behaviour. We suggest that swifts optimize their flight behaviour to adapt to favourable night-time light conditions, driven by light-responsive and size-dependent vertical insect stratification and weather conditions.


Assuntos
Aves , Voo Animal , Animais , Voo Animal/fisiologia , Aves/fisiologia , Insetos
2.
Molecules ; 26(20)2021 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-34684680

RESUMO

A series of fourteen 2-aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones was prepared at room temperature by T3P-mediated cyclization of N-phenyl-C-aryl imines with thionicotinic acid, two difficult substrates. The reactions were operationally simple, did not require specialized equipment or anhydrous solvents, could be performed as either two or three component reactions, and gave moderate-good yields as high as 63%. This provides ready access to N-phenyl compounds in this family, which have been generally difficult to prepare. As part of the study, the first crystal structure of neutral thionicotinic acid is also reported, and showed the molecule to be in the form of the thione tautomer. Additionally, the synthesized compounds were tested against T. brucei, the causative agent of Human African Sleeping Sickness. Screening at 50 µM concentration showed that five of the compounds strongly inhibited growth and killed parasites.


Assuntos
Tiazinas , Trypanosoma brucei brucei/efeitos dos fármacos , Anidridos/química , Animais , Antiprotozoários/síntese química , Antiprotozoários/farmacologia , Organofosfonatos/química , Tiazinas/síntese química , Tiazinas/farmacologia
3.
J Am Chem Soc ; 142(18): 8211-8222, 2020 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-32281385

RESUMO

The synthesis of two-dimensional (2D) zeolites has garnered attention due to their superior properties for applications that span catalysis to selective separations. Prior studies of 2D zeolite catalysts demonstrated enhanced mass transport for improved catalyst lifetime and selectivity. Moreover, the significantly higher external surface area of 2D materials allows for reactions of bulky molecules too large to access interior pores. There are relatively few protocols for preparing 2D materials, owing to the difficultly of capping growth in one direction to only a few unit cells. To accomplish this, it is often necessary to employ complex, commercially unavailable organic structure-directing agents (OSDAs) prepared via multistep synthesis. However, a small subset of zeolite structures exist as naturally layered materials where postsynthesis steps can be used to exfoliate samples and produce ultrathin 2D nanosheets. In this study, we selected a common layered zeolite, the MWW framework, to explore methods of preparing 2D nanosheets via one-pot synthesis in the absence of complex organic templates. Using a combination of high-resolution microscopy and spectroscopy, we show that 2D MMW-type layers with an average thickness of 3.5 nm (ca. 1.5 unit cells) can be generated using the surfactant cetyltrimethylammonium (CTA), which operates as a dual OSDA and exfoliating agent to affect Al siting and to eliminate the need for postsynthesis exfoliation, respectively. We tested these 2D catalysts using a model reaction that assesses external (surface) Brønsted acid sites and observed a marked increase in the conversion relative to three-dimensional MWW (MCM-22) and 2D layers prepared from postsynthesis exfoliation (ITQ-2). Collectively, our findings identify a facile and effective route to directly synthesize 2D MWW-type materials, which may prove to be more broadly applicable to other layered zeolites.

4.
Clin Infect Dis ; 66(7): 1120-1121, 2018 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-29300859

RESUMO

Zikavirus (ZIKV) is an emerging viral pathogen that continues to spread throughout different regions of the world. Herein we report a case that provides further evidence that ZIKV transmission can occur through breastfeeding by providing a detailed clinical, genomic, and virological case-based description.


Assuntos
Aleitamento Materno/efeitos adversos , Transmissão Vertical de Doenças Infecciosas , Leite Humano/virologia , Infecção por Zika virus/transmissão , Adulto , Feminino , Genoma Viral , Humanos , Lactente , Mães , Reação em Cadeia da Polimerase em Tempo Real , Venezuela , Zika virus/genética , Zika virus/isolamento & purificação
5.
Oecologia ; 188(3): 683-693, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30094635

RESUMO

Animals living on the earth's surface are protected from the damaging effects of solar ultraviolet (UV) radiation by melanin pigments that color their integument. UV levels that reach the earth's surface vary spatially, but the role of UV exposure in shaping clinal variations in animal pigmentation has never been tested. Here, we show at a continental scale in Europe that golden eagles Aquila chrysaetos reared in territories with a high solar UV-B radiation exposure deposit lower amounts of the sulphurated form of melanin (pheomelanin) in feathers and consequently develop darker plumage phenotypes than eagles from territories with lower radiation exposure. This clinal variation in pigmentation is also explained by terrestrial γ radiation levels in the rearing territories by a similar effect on the pheomelanin content of feathers, unveiling natural radioactivity as a previously unsuspected factor shaping animal pigmentation. These findings show for the first time the potential of solar and terrestrial radiations to explain pigmentation phenotype diversity in animals, including humans, at large spatial scales.


Assuntos
Águias , Pigmentação , Animais , Cor , Europa (Continente) , Plumas , Humanos , Melaninas
6.
Inorg Chem ; 56(6): 3214-3226, 2017 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-28277679

RESUMO

A series of rhenium tricarbonyl complexes coordinated by asymmetric diimine ligands containing a pyridine moiety bound to an oxazoline ring were synthesized, structurally and electrochemically characterized, and screened for CO2 reduction ability. The reported complexes are of the type Re(N-N)(CO)3Cl, with N-N = 2-(pyridin-2-yl)-4,5-dihydrooxazole (1), 5-methyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (2), and 5-phenyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (3). The electrocatalytic reduction of CO2 by these complexes was observed in a variety of solvents and proceeds more quickly in acetonitrile than in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The analysis of the catalytic cycle for electrochemical CO2 reduction by 1 in acetonitrile using density functional theory (DFT) supports the C-O bond cleavage step being the rate-determining step (RDS) (ΔG⧧ = 27.2 kcal mol-1). The dependency of the turnover frequencies (TOFs) on the donor number (DN) of the solvent also supports that C-O bond cleavage is the rate-determining step. Moreover, the calculations using explicit solvent molecules indicate that the solvent dependence likely arises from a protonation-first mechanism. Unlike other complexes derived from fac-Re(bpy)(CO)3Cl (I; bpy = 2,2'-bipyridine), in which one of the pyridyl moieties in the bpy ligand is replaced by another imine, no catalytic enhancement occurs during the first reduction potential. Remarkably, catalysts 1 and 2 display relative turnover frequencies, (icat/ip)2, up to 7 times larger than that of I.

7.
Physiol Plant ; 156(1): 29-39, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26362993

RESUMO

Plants with the crassulacean acid metabolism (CAM) express high-metabolic plasticity, to adjust to environmental stresses. This article hypothesizes that irradiance and nocturnal temperatures are the major limitations for CAM at higher latitudes such as the Azores (37°45'N). Circadian CAM expression in Ananas comosus L. Merr. (pineapple) was assessed by the diurnal pattern of leaf carbon fixation into l-malate at the solstices and equinoxes, and confirmed by determining maximal phosphoenolpyruvate carboxylase (PEPC) activity in plant material. Metabolic adjustments to environmental conditions were confirmed by gas exchange measurements, and integrated with environmental data to determine CAM's limiting factors: light and temperature. CAM plasticity was observed at the equinoxes, under similar photoperiods, but different environmental conditions. In spring, CAM expression was similar between vegetative and flowering plants, while in autumn, flowering (before anthesis) and fructifying (with fully developed fruit before ripening) plants accumulated more l-malate. Below 100 µmol m(-2) s(-1) , CAM phase I was extended, reducing CAM phase III during the day. Carbon fixation inhibition may occur by two major pathways: nocturnal temperature (<15°C) inhibiting PEPC activity and l-malate accumulation; and low irradiance influencing the interplay between CAM phase I and III, affecting carboxylation and decarboxylation. Both have important consequences for plant development in autumn and winter. Observations were confirmed by flowering time prediction using environmental data, emphasizing that CAM expression had a strong seasonal regulation due to a complex network response to light and temperature, allowing pineapple to survive in environments not suitable for high productivity.


Assuntos
Ananas/fisiologia , Regulação da Expressão Gênica de Plantas , Malatos/metabolismo , Ananas/efeitos da radiação , Ciclo do Carbono , Clima , Meio Ambiente , Flores/fisiologia , Flores/efeitos da radiação , Luz , Fotoperíodo , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Transpiração Vegetal/fisiologia , Estações do Ano , Temperatura , Fatores de Tempo
8.
Angew Chem Int Ed Engl ; 55(3): 1113-7, 2016 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-26636667

RESUMO

While momentum transfer from active particles to their immediate surroundings has been studied for both synthetic and biological micron-scale systems, a similar phenomenon was presumed unlikely to exist at smaller length scales due to the dominance of viscosity in the ultralow Reynolds number regime. Using diffusion NMR spectroscopy, we studied the motion of two passive tracers--tetramethylsilane and benzene--dissolved in an organic solution of active Grubbs catalyst. Significant enhancements in diffusion were observed for both the tracers and the catalyst as a function of reaction rate. A similar behavior was also observed for the enzyme urease in aqueous solution. Surprisingly, momentum transfer at the molecular scale closely resembles that reported for microscale systems and appears to be independent of swimming mechanism. Our work provides new insight into the role of active particles on advection and mixing at the Ångström scale.

9.
Pediatr Blood Cancer ; 61(5): 827-32, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24376241

RESUMO

BACKGROUND: The aim of this paper is to describe the results of acute lymphoblastic leukemia (ALL) treatment in Nicaragua from 1995 to 2005 in the context of an international cooperation program. PROCEDURES: Patients <18 years with ALL were treated with two consecutive protocols (1995 and 2000). After a steroid prophase, a three-drug induction was administered in protocol 1995, and a four-drug induction, including asparaginase, was administered in protocol 2000. In protocol 2000, a modified BFM phase IB with cyclophosphamide, 6-mercaptopurine and cytosine arabinoside was administered to patients at high risk (HR), who also received IV methotrexate (500 mg/m(2)) in the consolidation phase. Reinduction consisted of dexamethasone, vincristine, doxorubicin, cytosine arabinoside, and 6-thioguanine administered over 7 (protocol 1995) or 4 (protocol 2000) weeks; reinduction was repeated twice for patients at HR. Maintenance consisted of p.o. 6-mercaptopurine and methotrexate, and vincristine and dexamethasone pulses were added in the 2000 study. The total duration of therapy was 24 months. RESULTS: In total, 540 patients were treated. Overall, 7% of patients died during induction, and 9% abandoned treatment. At 5 and 10 years from diagnosis, event-free survival (EFS) rates of 38.1% and 36.6%, respectively, and overall survival rates of 48.0% and 39.6%, respectively, were obtained, considering abandonment as an event. CONCLUSIONS: In our experience, a 10-year EFS of 36.6% was achieved in a country with limited resources. Factors limiting a higher success rate were treatment abandonment and a high relapse rate.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Recidiva Local de Neoplasia/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Adolescente , Criança , Pré-Escolar , Feminino , Seguimentos , Humanos , Lactente , Cooperação Internacional , Masculino , Recidiva Local de Neoplasia/mortalidade , Nicarágua , Leucemia-Linfoma Linfoblástico de Células Precursoras/mortalidade , Prognóstico , Taxa de Sobrevida , Fatores de Tempo
10.
Rev Peru Med Exp Salud Publica ; 41(1): 46-53, 2024 May 27.
Artigo em Espanhol, Inglês | MEDLINE | ID: mdl-38808844

RESUMO

OBJECTIVE.: Motivation for the study. Dengue prevention and control is based on the control of its vector. This study was conducted because of the need to know the costs associated with Aedes aegypti control in a region that carries out planned vector control activities. Main findings. The costs incurred in dengue vector control in the Loreto region in 2017 and 2018 amounted to PEN 4,066,380.25 and PEN 3,807,858.73, respectively. Implications. Knowing the cost of vector control activities will allow us to better plan these activities and have a basis for cost-effectiveness studies with other methods of prevention and control of dengue. To estimate the costs incurred in the control of Aedes aegypti in the Loreto region, during the years 2017 and 2018. MATERIALS AND METHODS.: We conducted a partial retrospective economic evaluation of the costs of Aedes aegypti control of the Regional Health Directorate Loreto, during the implementation of the Regional Plan for Surveillance and Control of Aedes aegypti. Documentation such as plans, intervention reports and payment slips were reviewed, and interviews were conducted with professional personnel involved in vector control, on the costs of control interventions. RESULTS.: We found that the costs incurred in dengue vector control in the Loreto Region in the two years were: PEN 3,807,858 and PEN 4,066,380 during 2017 and 2018, respectively (USD 1,175,264 and USD 1,1210,232 at the 2017 and 2018 exchange rate). However, the effect of control activities is short-lived. CONCLUSIONS.: The high cost involved in vector control with the methods currently used and the short duration of its effect make it unsustainable. Studies should be conducted in order to find other more efficient methods for dengue control.


OBJETIVO.: Motivación para realizar el estudio. La prevención y control del dengue se basa en el control de su vector. Este estudio se realizó por la necesidad de conocer los costos asociados al control Aedes aegypti en una región que realiza actividades planificadas de control vectorial. Principales hallazgos. Los costos incurridos en el control del vector del dengue en la región Loreto en los años 2017 y 2018, ascienden a 4,066,380.25 y 3,807,858.73 PEN, respectivamente. Implicancias. Conocer el costo de las actividades de control vectorial nos permitirá planificar mejor estas actividades y tener una base para estudios de costo efectividad con otros métodos de prevención y control del dengue. Estimar los costos incurridos en el control del Aedes aegypti en la región Loreto, en los años 2017 y 2018. MATERIALES Y MÉTODOS.: Se realizó una evaluación económica retrospectiva parcial de los costos del control del Aedes aegypti de la Dirección Regional de Salud Loreto, durante la ejecución del Plan Regional de Vigilancia y Control de Aedes aegypti. Se revisó documentación como planes, informes de intervenciones y planillas de pago y se realizaron entrevistas al personal profesional implicado en el control vectorial, sobre los costos de las intervenciones de control. RESULTADOS.: Se halló, que los costos incurridos en el control del vector del dengue en la Región Loreto en los dos años estudiados ascienden a: 3,807,858 PEN y 4,066,380 PEN durante el 2017 y 2018, respectivamente (1´175,264 USD y 1´1210,232 USD al tipo de cambio del 2017 y 2018). Sin embargo, el efecto de las actividades de control es de corta duración. CONCLUSIONES.: El alto costo que implica el control vectorial con los métodos usados actualmente y la corta duración de su efecto lo hace insostenible. Se deben realizar estudios para hallar otros métodos más eficientes para el control del dengue.


Assuntos
Aedes , Dengue , Controle de Mosquitos , Mosquitos Vetores , Animais , Dengue/prevenção & controle , Dengue/economia , Dengue/transmissão , Peru , Controle de Mosquitos/economia , Controle de Mosquitos/métodos , Estudos Retrospectivos , Humanos , Custos e Análise de Custo
11.
J Neurol Surg Rep ; 85(2): e59-e65, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38742141

RESUMO

Introduction Hydrocephalus is a condition characterized by the abnormal accumulation of cerebrospinal fluid within the brain's ventricular system. It can stem from obstructive and nonobstructive causes. Pregnancy introduces physiopathological changes that may heighten the risk of developing or worsening symptomatic hydrocephalus. Nevertheless, comprehensive reports on this aspect, especially regarding surgical interventions, remain scarce. Case Report A young woman with a history of recurrent headaches experienced a worsening of her symptoms at the onset of her pregnancy. A magnetic resonance imaging (MRI) in the first trimester revealed increased ventricular dilation, indicating an obstructive cause due to aqueduct stenosis. During a neurosurgical board meeting, treatment options were discussed, considering the identifiable obstruction, the heightened intra-abdominal pressure associated with pregnancy, and the risk of ventricular shunt dysfunction. The patient underwent an endoscopic third ventriculostomy (ETV) without complications, leading to both symptom relief and a successful conclusion to the pregnancy. Discussion Neurosurgical procedures in pregnant women are uncommon due to the increased risks to both the mother and the fetus. However, when performed by a qualified multidisciplinary team, they can lead to positive outcomes. In cases of hydrocephalus during pregnancy, ETV appears to be a viable alternative for surgical intervention, particularly when hydrocephalus becomes symptomatic and an obstructive cause is identified, whether in patients with existing shunts or those with newly developed hydrocephalus.

12.
Arch Biochem Biophys ; 539(2): 133-41, 2013 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-23999492

RESUMO

Previous analysis of carotenoids extracted from the burgundy plumage of the Pompadour Cotinga (Xipholena punicea) revealed six novel keto-carotenoid pigments with methoxyl groups in the C3-position of one or both ß-rings. High performance liquid chromatography (HPLC), mass spectrometry, chemical analysis and, in some instances (1)H NMR spectroscopy were employed to determine the structures of the molecules. Further analysis by NMR was precluded due to lack of material. The recent acquisition of multiple feathers from X. punicea specimens has made it possible to complete this work using correlated homonuclear spectroscopy (COSY), nuclear overhauser effect spectroscopy (NOESY) and (1)H NMR. These new data conclusively confirm the structures of the six methoxy-carotenoids suggested by the earlier work. In addition, the resonance positions of the protons from the novel 3-methoxy-4-keto-ß-ring and 2,3-didehydro-3-methoxy-4-keto-ß-ring moieties are reported here for the first time.


Assuntos
Carotenoides/análise , Plumas/química , Passeriformes , Animais , Carotenoides/isolamento & purificação , Carotenoides/metabolismo , Cromatografia Líquida de Alta Pressão , Plumas/metabolismo , Masculino , Espectrometria de Massas , Ressonância Magnética Nuclear Biomolecular
13.
PLoS One ; 18(1): e0279914, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36652424

RESUMO

We studied the physicochemical characteristics and mycobiota associated to five key historic documents from Costa Rica, including the Independence Act of Costa Rica from 1821. We used nondestructive techniques (i.e., ATR-FTIR and XRF) to determine paper and ink composition. Results show that some documents are composed of cotton-based paper, whereas others were made of wood cellulose with an increased lignin content. We also determined that the ink employed in some of the documents is ferrogallic. Cultivation and molecular techniques were used to characterize the fungi inhabiting the documents. In total, 22 fungal isolates were obtained: 15 from the wood-cellulose-based documents and seven from the other three cotton-based. We also tested the cellulolytic activity of the recovered fungi; 95% of the fungi presented cellulolytic activity correlated to their ability to cause deterioration of the paper. Results suggest that cotton-based paper is the most resistant to fungal colonization and that most of the isolates have cellulolytic activity. This work increases the knowledge of the fungal diversity that inhabits historic documents and its relationship with paper composition and provides valuable information to develop strategies to conserve and restore these invaluable documents.


Assuntos
Celulose , Fungos , Costa Rica , Lignina , Madeira
14.
Acta Crystallogr E Crystallogr Commun ; 79(Pt 3): 221-225, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36909997

RESUMO

The title sulfones, 2,3-diphenyl-2,3-di-hydro-4H-1,3-benzo-thia-zine-1,1,4-trione, C20H15NO3S, and 2,3-diphenyl-2,3-di-hydro-4H-pyrido[3,2-e][1,3]thia-zine-1,1,4-trione, C19H14N2O3S, crystallize in space group P21/n with two mol-ecules in each of the asymmetric units and have almost identical unit cells and extended structures. In both structures, the thia-zine rings exhibit a screw-boat pucker. The inter-molecular inter-actions observed are C-H⋯O-type hydrogen bonds and parallel partial π-π stacking between the fused aromatic rings (benzo- or pyrido-) of the core of the mol-ecules within each asymmetric unit, and also connecting to mol-ecules with translational periodicity in the a-axis direction in what can be described as columns (two per asymmetric unit) of stacked mol-ecules with alternating chirality. The pendant phenyl groups of both mol-ecules do not participate in aromatic ring inter-actions.

15.
J Hum Kinet ; 82: 51-59, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36196353

RESUMO

We analyzed the Smart Groin Trainer device's validity and reliability to measure the isometric hip adduction strength during the adductor squeeze strength test. Fifteen professional soccer players (25.33±4.06 years) and fifteen university students (21.60±1.76 years) participated in this study. All participants performed the squeeze strength test using two portable dynamometers: Smart Groin Trainer and Globus Ergometer. Three maximal isometric hip adduction contractions lasting 5s, interspersed by 3min rest intervals, were performed. Reliability was analyzed with intraclass correlation coefficients, standard error of measurements, and minimal detectable change. The absolute percent error and inter-device accuracy were also analyzed. Correlation analysis assessed the inter-device concurrent validity. The results found no significant differences (p>0.05) between devices in the squeeze strength test values in soccer players and university students. Inter-device comparisons revealed excellent levels of reliability and accuracy in soccer players. Concurrent validity measures revealed strong inter-device relationships in soccer players (r=0.89) and very strong relationships in university students (r=0.99). Intra-device analysis using the Smart Groin Trainer showed excellent relative and absolute reliability in tested soccer players. Our data demonstrated excellent levels of agreement between both dynamometers during the squeeze strength test, suggesting the Smart Groin Trainer as a valid, reliable, and accurate device to measure isometric hip adduction strength.

16.
Zookeys ; 1040: 1-24, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34140821

RESUMO

Given the potential interest in targeting Solenocera acuminata in a new deep-sea fishery in the Colombian Caribbean, biological information is needed to support the management of this species. The objective of this study is to provide biological information about size structure, size at sexual maturity, morphometric relationships, abundances and spatial and bathymetric distribution of S. acuminata in the Colombian Caribbean. Specimens of S. acuminata were collected during four deep-sea prospecting surveys in the Colombian Caribbean Sea, which were conducted between Punta Gallinas and the Gulf of Uraba. A total of 87 exploratory fishing trawls were made between 100 and 550 m depth. Sexual dimorphism was evident, with males being smaller than females. The size at sexual maturity of the females was 95.2 mm total length (23.82 mm CL). Relatively high biomass values were found in the northern zone of the Colombian Caribbean, between Santa Marta and Riohacha. In the southern zone, higher biomass was found between Cartagena and Morrosquillo Gulf. The biomass of S. acuminata was higher at night (mean 1.82 kg/km2) than during daylight (mean 0.15 kg/km2). This species was distributed between 150 and 400 m depth and the highest biomass was associated with depths between 330 and 380 m. Before starting a new fishery, more research is needed to understand the life cycle parameters of deep-sea resources, such as growth, reproduction, recruitment, mortality, spawning areas and times, nursery areas and associated biodiversity.

17.
Sci Total Environ ; 797: 149228, 2021 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-34346385

RESUMO

Wastewaters contaminated with nitrogenous pollutants, derived from anthropogenic activities, have exacerbated our ecosystems sparking environmental problems, such as eutrophication and acidification of water reservoirs, emission of greenhouse gases, death of aquatic organisms, among others. Wastewater treatment facilities (WWTF) combining nitrification and denitrification, and lately partial nitrification coupled to anaerobic ammonium oxidation (anammox), have traditionally been applied for the removal of nitrogen from wastewaters. The present work provides a comprehensive review of the recent biotechnologies developed in which nitrogen-removing processes are relevant for the treatment of both wastewaters and gas emissions. These novel processes include the anammox process with alternative electron acceptors, such as sulfate (sulfammox), ferric iron (feammox), and anodes in microbial electrolysis cells (anodic anammox). New technologies that couple nitrate/nitrite reduction with the oxidation of methane, H2S, volatile methyl siloxanes, and other volatile organic compounds are also described. The potential of these processes for (i) minimizing greenhouse gas emissions from WWTF, (ii) biogas purification, and (iii) air pollution control is critically discussed considering the factors that might trigger N2O release during nitrate/nitrite reduction. Moreover, this review provides a discussion on the main challenges to tackle towards the consolidation of these novel biotechnologies.


Assuntos
Compostos de Amônio , Purificação da Água , Anaerobiose , Reatores Biológicos , Biotecnologia , Desnitrificação , Ecossistema , Nitrogênio , Oxirredução , Águas Residuárias
18.
Chem Sci ; 12(3): 969-975, 2020 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-34163863

RESUMO

Although synthetic organic electrochemistry (EC) has advanced significantly, net redox neutral electrosynthesis is quite rare. Two approaches have been employed to achieve this type of electrosynthesis. One relies on turnover of the product by the reactant in a chain mechanism. The other involves both oxidation on the anode and reduction on the cathode in which the radical cation or the radical anion of the product has to migrate between two electrodes. Herein, a home-built electrochemistry/mass spectrometry (EC/MS) platform was used to generate an N-cyclopropylaniline radical cation electrochemically and to monitor its reactivity toward alkenes by mass spectrometry (MS), which led to the discovery of a new redox neutral reaction of intermolecular [3 + 2] annulation of N-cyclopropylanilines and alkenes to provide an aniline-substituted 5-membered carbocycle via direct electrolysis (yield up to 81%). A chain mechanism, involving the regeneration of the substrate radical cation and the formation of the neutral product, is shown to be responsible for promoting such a redox neutral annulation reaction, as supported by experimental evidence of EC/MS.

19.
ACS Omega ; 5(9): 4668-4672, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32175513

RESUMO

The reaction of molybdenum(II) and chromium(II) acetates with squaric acid in degassed and deionized water under hydrothermal conditions at 150 °C is described. The products have been formulated as M2(µ-OH)2(µ-C4O4)2(H2O)4·2H2O, where M = Cr (1) and Mo (2), based on combustion elemental analysis, infrared spectroscopy, magic angle spinning (MAS) solid-state carbon-13 nuclear magnetic resonance (NMR), and single-crystal X-ray diffraction. The edge-shared bioctahedral structures involve doubly bridging hydroxide ligands and µ-squarate ligands. The chromium compound lacks a direct metal-metal-bonding interaction, while in contrast the molybdenum compound contains a Mo-Mo bond [2.491(2) Å]. The nature of the Mo-Mo-bonding interaction is compared with that of other similar d3-d3 dimers.

20.
J Colloid Interface Sci ; 571: 348-355, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32209489

RESUMO

This study explores the use of differential heating of magnetic nanoparticles with different sizes and compositions (MFe2O4 (M = Fe, Co)) for heteroplexed temporal controlled release of conjugated fluorophores from the surface of nanoparticles. By exploiting these differences, we were able to control the amount of hysteretic heating occurring with the distinct sets of magnetic nanoparticles using the same applied alternating magnetic field radio frequency (AMF-RF). Using thermally labile retro-Diels-Alder linkers conjugated to the surface of nanoparticles, the fluorescent payload from the different nanoparticles disengaged when sufficient energy was locally generated during hysteretic heating. 1H, 13C NMR, ESI-MS, and SIMS characterized the thermally responsive fluorescent cycloadducts used in this study; the Diels Alder cycloadducts were modeled using density functional theory (DFT) computations. The localized point heating of the different nanoparticle compositions drove the retro-Diels-Alder reaction at different times resulting in higher release rates of fluorophores from the CoFe2O4 compared to the Fe3O4 nanoparticles.

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