Converting levulinic acid (LA) to fuel precursors such as gama-valerolactone (GVL) and valeric acid (VA) via an efficient and low-cost method is of great significance. Herein, a series of ...free-standing electrodes consisting of metallic metals supported by carbon felts (CFs) were fabricated via a facile electro-deposition process. The resulting M/CFs (M = Pb, Cd, Co, Ni, Cu and Bi) electrodes were evaluated for electrocatalytic hydrogenation (ECH) of LA. The electrocatalytic activity of the electrodes was extensively studied by various electrochemical methods including cyclic voltammetry, linear sweep voltammetry and chronoamperometry measurements. The products of the ECH processes were analyzed by gas chromatography-mass spectrometry. Of all the prepared samples, the Pb/CFs and Cd/CFs electrodes showed superior performance for ECH of LA. The selectivity of VA reached up to 91.7% when the Pb/CFs was used and the conversion of LA reached to 57.2% using the Cd/CFs electrode, rendering them as one of the best electrodes for ECH reported in the literature. The effects of applied potentials on the ECH process were investigated. To further optimize the ECH performance of the Pb/CFs electrodes, several key parameters including deposition time, pH value of the electrolyte and reaction time were studied. When the electrodeposition time was 600 s and the concentration of sulfuric acid in the electrolyte was 0.5 M, the complete transformation of 0.2 M of LA was achieved after 6 h. This study may afford an alternative way to the conversion of LA to GVL or VA.
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•Self-standing M/CFs (M = Pb, Cd, Co, Cu, Ni and Bi) electrodes were studied for ECH of LA.•The Pb/CFs and Cd/CFs showed superior performance on activity and product selectivity.•The applied potentials affected the product distribution of the ECH processes.•The Pb/CFs exhibited the largest VA selectivity of 91.7%.•The effects of deposition time, pH value of the electrolyte and reaction time were explored.
Malate exudation through wheat (Triticum aestivum L) aluminium‐activated malate transporter 1 (TaALMT1) confers Al3+ tolerance at low pH, but is also activated by alkaline pH, and is regulated by and ...facilitates significant transport of gamma‐aminobutyric acid (GABA, a zwitterionic buffer). Therefore, TaALMT1 may facilitate acidification of an alkaline rhizosphere by promoting exudation of both malate and GABA. Here, the performance of wheat near isogenic lines ET8 (Al+3‐tolerant, high TaALMT1 expression) and ES8 (Al+3‐sensitive, low TaALMT1 expression) are compared. Root growth (at 5 weeks) was higher for ET8 than ES8 at pH 9. ET8 roots exuded more malate and GABA at high pH and acidified the rhizosphere more rapidly. GABA and malate exudation was enhanced at high pH by the addition of aluminate in both ET8 and transgenic barley expressing TaALMT1. Xenopus laevis oocytes expressing TaALMT1 acidified an alkaline media more rapidly than controls corresponding to higher GABA efflux. TaALMT1 expression did not change under alkaline conditions but key genes involved in GABA turnover changed in accordance with a high rate of GABA synthesis. We propose that TaALMT1 plays a role in alkaline tolerance by exuding malate and GABA, possibly coupled to proton efflux.
Aluminium‐activated malate transporter 1 in wheat roots is activated by high pH and enhanced by aluminate to release gamma‐aminobutyric acid and malate, which facilitates rhizosphere acidification and tolerance to high pH.
Este artigo é resultado de um projeto de pesquisa que buscou observar o uso da máquina retórica e poética da Antiguidade durante o conturbado período pombalino português e seu impacto na América ...Portuguesa. Entendemos que a Primeira Modernidade utilizou-se dos elementos discursivos legados pela Antiguidade como instrumento de construção prática e simbólica de um enunciado acerca dos conflitos que se desenrolavam nas colônias, e usamos como exemplo de análise e observação deste fenômeno o proêmio do poema O Uraguay, do autor luso-brasileiro Basílio da Gama.
A stereoselective approach to C-3′ methyl attached γ-lactam derivatives as the precursors of pyroglutamate core of oxazolomycins is described. The synthesis started from d-xylose and utilized ...3,3-heterosigmatropic rearrangement. The key lactamization was achieved with intramolecular aldol reaction and ring-closing metathesis. The accomplished stereoselective aldol cyclization was elucidated with Zimmerman-Traxler transition state models. Stereoselectivity of the aldol reaction was explained as a consequence of chelation and bridgehead atoms linkage. The present work also encompasses proposed structures of (E)- and (Z)- generated enolates during intramolecular aldol reaction. Although stereocenters were not formed during ring-closing metathesis, a stereospecific reduction of prepared double bond functionality was successfully accomplished.
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•Synthesis of γ-lactam derivatives as the precursors of pyroglutamate core of oxazolomycins was succesfully accomplished.•The key lactamization was achieved with intramolecular aldol reaction and ring-closing metathesis.•The stereoselective aldol cyclization was elucidated via Zimmerman-Traxler transition state models.
Gama-butirolakton (GBL) je zaradi lahke dostopnosti in nizke cene priljubljena rekreativna droga v nočnih klubih. Gre za prekurzor endogenega nevrotransmiterja, gama-hidroksibutirata (GHB), ki deluje ...kot agonist na receptorje GABAB in GHB v centralnem živčnem sistemu (CŽS). V nižjih odmerkih inhibira izločanje dopamina, povzroča evforične učinke in niža centralno inhibicijo. Višji odmerki spodbujajo izločanje opioidom podobnih substanc in povzročijo hitro depresijo CŽS. Odvisnost nastopi po nekaj tednih do mesecih vsakodnevne uporabe. Odtegnitev načeloma oponaša klinično sliko odtegnitve od alkohola in/ali benzodiazepinov. Predstavljamo primer odtegnitvenega sindroma od GBL, ki se je pokazal z razvojem delirija, zmedenostjo, halucinacijami in agitacijo. Zdravljenje vključuje visoke odmerke benzodiazepinov, po potrebi pa tudi barbiturate, antikonvulzive in antipsihotike.
ENTREVISTA COM JOÃO MALAIA Fortes, Rafael; Malaia, Joõo
Recorde, revista de história do esporte,
07/2021, Letnik:
14, Številka:
2
Journal Article
Odprti dostop
Joao Malaia is an assistant professor in the History Department at the Federal University of Santa Maria (Santa Maria, Brazil). In this interview, which took place through a videoconference on ...September 30, 2021, he speaks about his academic career, debates over his PhD dissertation, research interests, sport and general archives, sport history and economic history. A minha passagem pelo grupo de estudos Sport9 foi o momento em que, naquele processo todo, eu realmente entendi o que era ser pesquisador. A bolsa de posdoc era um terço do que eu ganhava dando aula nos colégios e cursinhos, entāo foi bem complicado, inclusive no aspecto familiar, de gerenciar os custos.
En este artículo se presenta una propuesta de automatización de un reactor discontinuo para la elaboración de polímeros por adición, en el cual tiene lugar una reacción química de carácter exotérmico ...generada en el proceso de polimerización. Se propone controlar la temperatura del producto mediante una estrategia de control de gama partida con controladores en cascada considerando el lazo de temperatura del producto como lazo primario y el de la temperatura de la camisa como lazo secundario. Se realiza el modelamiento fenomenológico del reactor a partir de balances de materia y energía para obtener la función de transferencia del sistema y estimar los parámetros de los controladores. Los resultados obtenidos en la simulación y el control del proceso evidencian el buen desempeño del sistema trabajando con el set-point de temperatura del proceso entre 92 °C y 96 °C; además, en este rango se observa una mejora significativa en la conversión monómero-polímero del producto.
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•GABA treatment enhanced lipid biosynthesis under salinity stress with fulvic acid.•GABA decreased ROS levels of QLY-1 under salinity stress with fulvic acid.•GABA regulated calcium ...signalling in QLY-1 under salinity stress with fulvic acid.•Calcium promoted lipid synthesis by regulating GABA shunt.
In this study, the cross-talk between gama-aminobutyric acid (GABA) and calcium ion (Ca2+) signalling in the regulation of lipid production and cell growth in microalgae under fulvic acid and salinity stress (FA-salinity treatment) was investigated. GABA enhanced the lipid content and lipid productivity rate considerably, which were 1.27 and 1.29 times higher than those of the control, respectively. The levels of biosynthetic gene transcription, GSH, Ca2+ and cellular GABA were promoted by GABA addition, but decreased the ROS levels. Furthermore, the application of Ca2+ also increased lipid synthesis by regulating ROS and GABA signalling and lipogenesis-related genes. These results indicated that cytosolic GABA and Ca2+ levels exert crucial cross-talk in the modulation of cell growth and lipid accumulation induced by FA-salinity treatment. Collectively, this study demonstrated the beneficial effects caused by induction of the combination of chemical compounds on lipid production and provided new insights into lipid synthesis in microalgae.
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