specific catalytic activity
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2021 ◽  
Vol 16 (2) ◽  
pp. 153-158
Author(s):  
Antônio Jussiê da Silva Solino ◽  
Juliana Santos Batista Oliveira ◽  
Sergio Augusto Cesnik ◽  
Kátia Regina Freitas Schwan-Estrada

Rare earth elements have been tested in control of plant diseases. Lanthanum (La) was tested in the control of Alternaria solani (in vitro) and tomato early blight (in vivo) using the concentration 0; 0.1; 0.2; 0.4 and 0.8 g L-1. In vitro, the concentration were diluted in V8 culture medium and evaluated for mycelial growth rate index (MGRI) and pathogen sporulation. In vivo, 24 hours after the application of concentration was inoculate the pathogen and 24 hours after the inoculation, leaflets were collected for quantification, the specific catalytic activity and guaiacol peroxidase. The severity of tomato early blight were also analyzed. As 0.27 and 0.28 g L-1 reduces 28% and 50% the MGRI and the sporulation, respectively. Peroxidase and catalase activity was increased by 298% and 151% in tomato treated with 0.5 and 0.4 g L-1de La, respectively. In vivo reduces AUDPC 70% when was applied 0.27 g L-1 La. Lanthanum can be used as resistance inducer in controlling tomato early blight.



2021 ◽  
Author(s):  
Yongseon Kim ◽  
Gregory Collinge ◽  
Mal Soon Lee ◽  
Konstantin Khivantsev ◽  
Sung June Cho ◽  
...  

The analogy between single atom catalysts (SACs) and molecular catalysts predicts that the specific catalytic activity of these systems is constant. We provide evidence that this prediction is not necessarily true. As a case in point, we show that the specific activity over ceria5 supported single Pd atoms linearly increases with metal atom density, originating from the cumulative enhancement of lattice oxygen mobility. The long-range electrostatic fingerprints (~1.5 nm) around each Pd site overlap with each other as surface Pd density increases, resulting in the observed deviation from constant specific activity. These cooperative effects exhaust previously active O atoms above a certain Pd density, leading to their permanent 10 removal and consequent drop in reaction rate. The findings of our combined experimental and computational study show that the specific catalytic activity of reducible oxide-supported single atom catalysts can be tuned by varying the surface density of single metal atoms.



2021 ◽  
Author(s):  
Yongseon Kim ◽  
Gregory Collinge ◽  
Mal Soon Lee ◽  
Konstantin Khivantsev ◽  
Sung June Cho ◽  
...  

The analogy between single atom catalysts (SACs) and molecular catalysts predicts that the specific catalytic activity of these systems is constant. We provide evidence that this prediction is not necessarily true. As a case in point, we show that the specific activity over ceria5 supported single Pd atoms linearly increases with metal atom density, originating from the cumulative enhancement of lattice oxygen mobility. The long-range electrostatic fingerprints (~1.5 nm) around each Pd site overlap with each other as surface Pd density increases, resulting in the observed deviation from constant specific activity. These cooperative effects exhaust previously active O atoms above a certain Pd density, leading to their permanent 10 removal and consequent drop in reaction rate. The findings of our combined experimental and computational study show that the specific catalytic activity of reducible oxide-supported single atom catalysts can be tuned by varying the surface density of single metal atoms.



2020 ◽  
Vol 36 (3) ◽  
pp. 369-400 ◽  
Author(s):  
Suja George ◽  
Dhiraj Mehta ◽  
Virendra Kumar Saharan

AbstractFluorosis is a major scourge in many countries caused by prolonged consumption of drinking water with high fluoride content found in groundwater resources. Hydroxyapatite (Hap) and its composite forms are excellent biomaterials that recently gained attention as efficient adsorbents, owing to its physical and chemical nature as it can substitute both cationic and anionic complexes present in an aqueous solution in its atomic arrangement. Its biological nature, biocompatibility and biodegradability along with its chemical characteristics such as crystallinity, stability, ion adsorption capability and highly specific catalytic activity make it suitable for a variety of applications especially in water treatment for fluoride removal. This review describes various techniques for synthesis of a wide variety of biogenic, synthetic, composite and modified forms of Hap for application in water defluoridation. Hap derived from natural sources or synthesized using conventional methods, hydrothermal, sol-gel or advanced sonication-cum-precipitation technique varied in terms of its crystallinity, structure, size, etc., which affect the fluoride removal capacity. The advantage and disadvantages of various synthesis methods, process parameters and product characteristics have been compiled, which may help to identify a suitable synthesis method for a desired Hap product for potential application and future perspectives in water treatment.



2020 ◽  
Vol 2 (2) ◽  
pp. 669-678 ◽  
Author(s):  
Yuichi Negishi ◽  
Nobuyuki Shimizu ◽  
Kanako Funai ◽  
Ryo Kaneko ◽  
Kosuke Wakamatsu ◽  
...  

A Pt17 cluster was precisely loaded on γ-alumina and the resulting Pt17/γ-Al2O3 exhibited high catalytic activity for CO and C3H6 oxidation.





ACS Catalysis ◽  
2017 ◽  
Vol 7 (5) ◽  
pp. 3434-3445 ◽  
Author(s):  
Manuel J. S. Farias ◽  
William Cheuquepán ◽  
Auro A. Tanaka ◽  
Juan M. Feliu


2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Bi Bi Zainab Mazhari ◽  
Dayanand Agsar ◽  
M. V. N. Ambika Prasad

Paper biosensor was developed using Tyr-AuNps bioconjugate produced byStreptomycesfor the detection of phenol from the effluent of wine, paper, and plastic industries. Among three filter papers assessed, Whatman number 2 filter paper was proved to be the best paper base for the development of biosensor. Tyrosinase and gold nanoparticles being produced by a single novel isolateStreptomyces tuirusDBZ39 proved to be efficient bioconjugate for the detection of phenol constituents, due to its biocompatibility. The substrate specific catalytic activity of the tyrosinase and unique Surface Plasmon Resonance attribute of gold nanoparticles are the cause for efficient detection of phenol constituents from the effluent of wine, paper, and plastic industries in 3 min. The different types and quantity of phenolic constituents in various industrial effluents, such as phenol in wine, dopamine in paper, and catechol in plastic effluents, were accurately detected by the bioconjugate. The efficacy of tyrosinase in the detection of phenol constituents was expected to be enhanced by the gold nanoparticles because of their electron, optical, and magnetic properties. This novel paper strip biosensor could be cost-effective and efficient means of future devices for the detection of phenolic pollutants from any environmental samples.





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