scholarly journals Novel Combination of Quaternary AgFeNi2S4 Semiconductor In Graphene-TiO2 Nanocomposite For The Enhanced Electrophotocatalytic Reduction of CO2

2021 ◽  
Author(s):  
Zambaga Otgonbayar ◽  
Won Chun Oh
Keyword(s):  
Catalytic Activity ◽  
Preparation Method ◽  
Uv Light ◽  
Pechini Method ◽  
Hydrocarbon Fuels ◽  
Working Electrode ◽  
The Stability ◽  
Reduction Of Co2 ◽  
Positive Effect ◽  
Morphological State

Abstract For reduction of CO2 into hydrocarbon fuels, a quaternary AgFeNi2S4 semiconductor combined in Graphene-TiO2 nanocomposite material was synthesized via the Pechini method. The catalytic activity of the photocatalyst for photocatalytic and electrochemical CO2 evolution into hydrocarbon fuels was tested. The methanol yield under UV light was 8.679, 6.349, and 4.136 %, and the methanol yields under visible light were 6.291, 4.738, and 2.339 %, respectively. The stability and reusability of the photocatalyst remained high after a 4-cycle recycling test without a decrease in yield of the final photocatalytic CO2 reduction product. The enhanced photoreduction of CO2 through the as-prepared ternary photocatalyst can be ascribed to the catalyst's conformation and low recombination rate. In electrochemical CO2 reduction, the Faraday efficiency is the main parameter that defines the performance of the working electrode and the evolution of methanol. The Faraday efficiency of AFNSGT ternary nanocomposite was 44.25 %; this is an increase in the value of the Faraday efficiency, which proves that the design of the new nanocomposite successfully increases the activity of the working electrode and has a positive effect on the electrochemical reduction of CO2. The photocatalytic and electrochemical CO2 reduction data show that the preparation method, morphological state, and charge carrier properties of the photocatalyst are important for the catalytic activity and efficiency of the methanol evolution pathway.

scholarly journals New Modeling of AgFeNi2S4-Graphene-TiO2 Ternary Nanocomposite Synthesized Via the Pechini Method for the Enhanced Electrophotocatalytic Reduction of CO2

2021 ◽  
Author(s):  
Zambaga Otgonbayar ◽  
Won-Chun Oh
Keyword(s):  
Catalytic Activity ◽  
Uv Light ◽  
Pechini Method ◽  
Chelating Agent ◽  
Hydrocarbon Fuels ◽  
Ternary Nanocomposite ◽  
Working Electrode ◽  
The Stability ◽  
Reduction Of Co2 ◽  
Positive Effect

Abstract For reduction of CO2 into hydrocarbon fuels, an AgFeNi2S4-Graphene-TiO2 ternary nanocomposite material was synthesized via the Pechini method. The Pechini method is based on a chelating agent which, together with ethylene glycol (C2H6O2) and citric acid (C6H8O7) as a chelating cation, can affect the structure and stability of the nanocomposite. The catalytic activity of the photocatalyst for photocatalytic and electrochemical CO2 evolution into hydrocarbon fuels was tested. The methanol yield under UV light was 8.679 %, 6.349 %, and 4.136 %, and the methanol yields under visible light was 6.291 %, 4.738 %, and 2.339 %, respectively. The stability and reusability of the photocatalyst remained high after a 4-cycle recycling test without a decrease in yield of the final photocatalytic CO2 reduction product. The enhanced photoreduction of CO2 through the as-prepared ternary photocatalyst can be ascribed to the catalyst's conformation and low recombination rate. In electrochemical CO2 reduction, the Faraday efficiency is the main parameter that defines the performance of the working electrode and the evolution of methanol. The Faraday efficiency of AFNSGT ternary nanocomposite was 44.25 %; this is an increase in the value of the Faraday efficiency, which proves that the design of the new nanocomposite successfully increases the activity of the working electrode and has a positive effect on the electrochemical reduction of CO2. The photocatalytic and electrochemical CO2 reduction data show that the preparation method, morphological state, and charge carrier properties of the photocatalyst are important for the catalytic activity and efficiency of the methanol evolution pathway. This study provides a strategy for fabrication of a new ternary nanocomposite based on 2D-structured graphene, TiO2, and a quaternary nanocomposite.

New Modeling of AgFeNi2S4-Graphene-TiO2 Ternary Nanocomposite with Chelate Compounds and Its Photocatalytic Reduction of CO2

2021 ◽  
Author(s):  
Zambaga Otgonbayar ◽  
Chong Hun Jung ◽  
Oh Won-Chun
Keyword(s):  
Catalytic Activity ◽  
Citric Acid ◽  
Solvothermal Method ◽  
High Catalytic Activity ◽  
Photogenerated Electrons ◽  
Methanol Formation ◽  
Nano Material ◽  
Chelate Compounds ◽  
The Stability ◽  
Reduction Of Co2

Abstract Herein, we synthesized the chalcogenide-quaternary nanocomposite loaded Graphene-based ternary photocatalyst via a modified solvothermal method. The preparation of quaternary nanocomposite was based on metallic citrate polymerization which used ethylene glycol (C2H6O2) and citric acid (C6H8O7) as chelate cations. The morphology and electrochemical properties of the as-prepared nano-material investigated by using a physical characterization equipment. Each result showed that the ternary photocatalyst was successfully synthesized and showed the low recombination rate of photogenerated electrons and holes, which defined the catalytic activity of the photocatalyst for CO2 evolution into hydrocarbon fuels under light irradiation. In addition, the stability and reusability of the photocatalyst were analyzed by a 6-times cycling test without loss of methanol formation by CO2 evolution. The graphene-based ternary photocatalyst offers a new nanomaterial with a new-model that protects the environment by showing high catalytic activity in reducing CO2 to methanol.

Sorbitol enhances the physicochemical stability of B12 vitamers

2020 ◽  
Vol 90 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Andrew Hadinata Lie ◽  
Maria V Chandra-Hioe ◽  
Jayashree Arcot
Keyword(s):  
Ascorbic Acid ◽  
Uv Light ◽  
Heat Exposure ◽  
Water Soluble ◽  
Uv Exposure ◽  
Physicochemical Stability ◽  
Before And After ◽  
The Stability

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

Metathesis Polymerization of Phenylacetylene by Tungsten Aryloxo Complexes

1995 ◽  
Vol 60 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Hynek Balcar ◽  
Jan Sedláček ◽  
Marta Pacovská ◽  
Vratislav Blechta
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Induction Period ◽  
Average Molecular Weight ◽  
Molar Fraction ◽  
Molar Ratio ◽  
Weight Average Molecular Weight ◽  
Polymer Yield ◽  
Positive Effect ◽  
Ligand Addition

Catalytic activity of the tungsten aryloxo complexes WCl5(OAr) and WOCl3(OAr), where Ar = 4-t-C4H9C6H4, 2,6-(t-C4H9)2C6H3, 2,6-Cl2C6H3, 2,4,6-Cl3C6H2, and 2,4,6-Br3C6H2 in polymerization of phenylacetylene (20 °C, monomer to catalyst molar ratio = 1 000) was studied. The activity of WCl5(OAr) as unicomponent catalysts increases with increasing electron withdrawing character of the -OAr ligand. Addition of two equivalents of organotin cocatalysts (Me4Sn, Bu4Sn, Ph4Sn, Bu3SnH) to WCl5(O-C6H2Cl3-2,4 ,6) has only slight positive effect (slightly higher polymer yield and/or molecular weight of poly(phenylacetylene)s was achieved). However, in the case of WOCl3(O-C6H3Cl2-2, 6) catalyst, it enhances the activity considerably by eliminating the induction period. Poly(phenylacetylene)s prepared with the catalysts studied have weight-average molecular weight ranging from 100 000 to 200 000. They are trans-prevailing and have relatively low molar fraction of monomer units comprised in cyclohexadiene sequences (about 6%).

scholarly journals Stability and ocular biodistribution of topically administered PLGA nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sean Swetledge ◽  
Renee Carter ◽  
Rhett Stout ◽  
Carlos E. Astete ◽  
Jangwook P. Jung ◽  
...  
Keyword(s):  
Uv Light ◽  
Light Exposure ◽  
Polymeric Nanoparticles ◽  
Plga Nanoparticles ◽  
Eye Disease ◽  
Control Group ◽  
Eye Tissues ◽  
Nanoparticle Morphology ◽  
The Stability

AbstractPolymeric nanoparticles have been investigated as potential delivery systems for therapeutic compounds to address many ailments including eye disease. The stability and spatiotemporal distribution of polymeric nanoparticles in the eye are important regarding the practical applicability and efficacy of the delivery system in treating eye disease. We selected poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with lutein, a carotenoid antioxidant associated with eye health, as our model ophthalmic nanodelivery system and evaluated its stability when suspended in various conditions involving temperature and light exposure. We also assessed the ocular biodistribution of the fluorescently labeled nanoparticle vehicle when administered topically. Lutein-loaded nanoparticles were stable in suspension when stored at 4 °C with only 26% lutein release and no significant lutein decay or changes in nanoparticle morphology. When stored at 25 °C and 37 °C, these NPs showed signs of bulk degradation, had significant lutein decay compared to 4 °C, and released over 40% lutein after 5 weeks in suspension. Lutein-loaded nanoparticles were also more resistant to photodegradation compared to free lutein when exposed to ultraviolet (UV) light, decaying approximately 5 times slower. When applied topically in vivo, Cy5-labled nanoparticles showed high uptake in exterior eye tissues including the cornea, episcleral tissue, and sclera. The choroid was the only inner eye tissue that was significantly higher than the control group. Decreased fluorescence in all exterior eye tissues and the choroid at 1 h compared to 30 min indicated rapid elimination of nanoparticles from the eye.

scholarly journals Inhibition or Facilitation? Contrasted Inter-Specific Interactions in Sphagnum under Laboratory and Field Conditions

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1554
Author(s):  
Chao Liu ◽  
Zhao-Jun Bu ◽  
Azim Mallik ◽  
Yong-Da Chen ◽  
Xue-Feng Hu ◽  
...  
Keyword(s):  
Field Experiment ◽  
Species Interactions ◽  
Laboratory Experiments ◽  
Resource Competition ◽  
Specific Interactions ◽  
Interaction Type ◽  
Negative Effects ◽  
Experiment Data ◽  
The Stability ◽  
Positive Effect

In a natural environment, plants usually interact with their neighbors predominantly through resource competition, allelopathy, and facilitation. The occurrence of the positive effect of allelopathy between peat mosses (Sphagnum L.) is rare, but it has been observed in a field experiment. It is unclear whether the stability of the water table level in peat induces positive vs. negative effects of allelopathy and how that is related to phenolic allelochemical production in Sphagnum. Based on field experiment data, we established a laboratory experiment with three neighborhood treatments to measure inter-specific interactions between Sphagnum angustifolium (Russ.) C. Jens and Sphagnum magellanicum Brid. We found that the two species were strongly suppressed by the allelopathic effects of each other. S. magellanicum allelopathically facilitated S. angustifolium in the field but inhibited it in the laboratory, and relative allelopathy intensity appeared to be positively related to the content of released phenolics. We conclude that the interaction type and intensity between plants are dependent on environmental conditions. The concentration of phenolics alone may not explain the type and relative intensity of allelopathy. Carefully designed combined field and laboratory experiments are necessary to reveal the mechanism of species interactions in natural communities.

SHELL MATERIAL'S PERFORMANCE OF THE MICROCAPSULE FOR ELECTROLYTIC CO-DEPOSITION

2010 ◽  
Vol 24 (15n16) ◽  
pp. 3124-3130 ◽  
Author(s):  
HUI CONG LIU ◽  
XIU QING XU ◽  
WEI PING LI ◽  
YAN HONG GUO ◽  
LI-QUN ZHU
Keyword(s):  
Composite Coating ◽  
Methyl Cellulose ◽  
Water Vapor Permeability ◽  
Core Material ◽  
Vapor Permeability ◽  
Shell Material ◽  
The Core ◽  
Surface Performance ◽  
The Stability ◽  
Positive Effect

The shell material of microcapsules has an important effect on the electrolytic co-deposition behavior, the release of core material and the surface performance of composite coating. This paper discussed the tensile property and the stability of three shell materials including polyvinyl alcohol (PVA), gelatin and methyl cellulose (MC). It is found that these three shell materials have good mechanical strength and flexibility which are favorable to electrolytic co-deposition and stability of microcapsules in composite coating and that MC has well permeability and porosity which has a positive effect on the release of the core material in composite coating. Moreover, the study of the thermal properties and water vapor permeability of the three shell materials showed that their permeability improved with increase of temperature and humidity. In addition, the composite copper coating containing microcapsules with PVA, gelatin or MC as shell material was prepared respectively.

Effect of the ionizing radiation on the catalytic activity of the BASF K-3-10 catalyst in the low-temperature conversion of carbon monoxide by water vapour. Stability of the radiation catalytic effects

1986 ◽  
Vol 51 (8) ◽  
pp. 1571-1578 ◽  
Author(s):  
Alois Motl
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Low Temperature ◽  
Catalytic Effect ◽  
Catalytic Properties ◽  
Beta Radiation ◽  
Fast Neutrons ◽  
Time Interval ◽  
The Stability ◽  
Catalytic Effects

The radiation catalytic properties of the BASF K-3-10 catalyst were studied, namely the dependence of these effects on the time interval between the catalyst irradiation and the reaction itself and also on the length of the catalyst use. The catalytic effects decrease exponentially with the interval between the irradiation and the reaction if the catalyst is kept in the presence of air. The stability of effects induced by various types of radiations increases in the sequence beta radiation - gamma radiation - fast neutrons. The radiation catalytic effect stability in the reaction increases in the same sequence.

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