scholarly journals Preparation of a Flower-Like Immobilized D-Psicose 3-Epimerase with Enhanced Catalytic Performance

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 468 ◽  
Author(s):  
Lu Zheng ◽  
Yining Sun ◽  
Jing Wang ◽  
He Huang ◽  
Xin Geng ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Maximum Activity ◽  
Organic Component ◽  
Inorganic Component ◽  
Optimum Conditions ◽  
Thermal Stabilities ◽  
Nanometer Size ◽  
Cobalt Phosphate ◽  
Reaction Cycles

In this present study, we proposed a smart biomineralization method for creating hybrid organic–inorganic nanoflowers using a Co2+-dependent enzyme (D-psicose 3-epimerase; DPEase) as the organic component and cobalt phosphate as the inorganic component. The prepared nanoflowers have many separated petals that have a nanometer size. Under optimum conditions (60 °C and pH of 8.5), the nanoflower can display its maximum activity (36.2 U/mg), which is about 7.2-fold higher than free DPEase. Furthermore, the immobilized DPEase presents enhanced pH and thermal stabilities. The DPEase-nanoflower maintained about 90% of its activity after six reaction cycles, highlighting its excellent reusability.

Solventless synthesis of solketal with commercially available sulfonic acid based ion exchange resins and their catalytic performance

2017 ◽  
Vol 6 (1) ◽  
Author(s):  
Jesús Esteban ◽  
Félix García-Ochoa ◽  
Miguel Ladero
Keyword(s):  
Ion Exchange ◽  
Sulfonic Acid ◽  
Catalytic Performance ◽  
Maximum Activity ◽  
Ion Exchange Resins ◽  
Active Centers ◽  
Ease Of Access ◽  
Exchange Resins ◽  
Solventless Synthesis

AbstractAs a means to valorize glycerol, the synthesis of solketal through a ketalization reaction with acetone was performed. Mild solventless conditions were applied to test the activity of different commercially available sulfonic ion exchange resins that had already been used for other applications, namely: Amberlyst 35dry, Amberlyst 36dry, Purolite CT275DR, Purolite CT276 and Lewatit GF101. Thorough characterization of the resins is herein provided and discussed, including acidity, elemental analysis, thermogravimetric, 13C-NMR, surface area and pore size distribution measurements. Lewatit GF101 showed the best performance reaching a yield to solketal of 47% after 6 h of operation at 313 K using a molar excess of acetone to glycerol of 4.5 to 1, owing to a greater availability of active centers as well as the ease of access to them than in the rest of the resins. Additionally, reutilization with and without regeneration was performed in up to five cycles, showing that Purolite CT276 had the lowest relative drop of its maximum activity, despite being the least active in each of the cycles.

Three dimensional nitrogen-doped graphene hydrogels with in situ deposited cobalt phosphate nanoclusters for efficient oxygen evolution in a neutral electrolyte

2016 ◽  
Vol 1 (1) ◽  
pp. 41-44 ◽  
Author(s):  
Anthony Vasileff ◽  
Sheng Chen ◽  
Shi Zhang Qiao
Keyword(s):  
Oxygen Evolution ◽  
Three Dimensional ◽  
Catalytic Performance ◽  
Nitrogen Doped ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene ◽  
Neutral Electrolyte ◽  
Cobalt Phosphate ◽  
Excellent Catalytic Performance

Nitrogen doped graphene hydrogel electrocatalysts with in situ deposited cobalt phosphate demonstrated excellent catalytic performance toward oxygen evolution in a neutral electrolyte.

Transition metal ions regulate the catalytic performance of Ti0.8M0.2Ce0.2O2+x for the NH3-SCR of NO: the acidic mechanism

RSC Advances ◽  
2015 ◽  
Vol 5 (10) ◽  
pp. 7597-7603 ◽  
Author(s):  
Yuesong Shen ◽  
Yun Su ◽  
Yifan Ma
Keyword(s):  
Transition Metal Ions ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Acid Strength ◽  
Maximum Activity ◽  
Lewis Acid Sites ◽  
Nh3 Scr ◽  
Scr Of No ◽  
Temperature Window ◽  
Active Temperature

The maximum activity is dependent on the number of Lewis acid sites, and the active temperature window is dependent on the acid strength.

scholarly journals Cow Dung Substrate for the Potential Production of Alkaline Proteases by Pseudomonas putida Strain AT in Solid-State Fermentation

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Ponnuswamy Vijayaraghavan ◽  
Sreekumar Saranya ◽  
Samuel Gnana Prakash Vincent
Keyword(s):  
Solid State ◽  
Pseudomonas Putida ◽  
Solid State Fermentation ◽  
Maximum Activity ◽  
Protease Production ◽  
Cow Dung ◽  
Alkaline Proteases ◽  
Optimum Conditions ◽  
Potential Production ◽  
Fermentation Period

Cow dung and agroresidues were used as the substrates for the production of alkaline proteases by Pseudomonas putida strain AT in solid-state fermentation. Among the various substrates evaluated, cow dung supported maximum (1351±217 U/g) protease production. The optimum conditions for the production of alkaline proteases were a fermentation period of 48 h, 120% (v/w) moisture, pH 9, and the addition of 6% (v/w) inoculum, 1.5% (w/w) trehalose, and 2.0% (w/w) yeast extract to the cow dung substrate. The enzyme was active over a range of temperatures (50–70°C) and pHs (8–10), with maximum activity at 60°C and pH 9. These enzymes showed stability towards surfactants, detergents, and solvent and digested various natural proteins.

Application of activated carbon supported cobalt(II) tetraaminophthalocyanine towards preparation of dimethyl disulfide

2019 ◽  
Vol 23 (03) ◽  
pp. 267-278
Author(s):  
Zhiliang Cheng ◽  
Mingxing Dai ◽  
Xuejun Quan ◽  
Shuo Li ◽  
Daomin Zheng ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Supported Catalyst ◽  
Dimethyl Disulfide ◽  
Catalytic Performance ◽  
Optimum Conditions ◽  
Chemical Grafting ◽  
Ft Ir ◽  
Catalyst Dosage ◽  
Yield Formula ◽  
Application Prospects

Dimethyl disulfide (DMDS) is an important fine chemical that can be prepared by the refined Merox process of oxidation of sodium methyl mercaptide (SMM) in the presence of a catalyst. In this paper, a novel activated carbon (AC) supported cobalt(II) tetraaminophthalocyanine (AC-CoTAPc) catalyst was prepared by the chemical grafting method. EA, UV-vis, FT-IR, BET and XPS were used to characterize the structure of the new catalyst. The effects of reaction time, catalyst dosage, reaction temperature and oxygen pressure on SMM conversion per pass (CPP[Formula: see text], yield (Yield[Formula: see text] and purity of DMDS product (Purity[Formula: see text] were investigated to evaluate the catalytic performance of new AC-CoTAPc catalyst. The results show that free CoTAPc is easily dissolved in this DMDS product, which needs extra post treatment and cannot be reused. The supported catalyst AC-CoTAPc can easily solve these problems and can be properly reused four times to get Yield[Formula: see text] and CPP[Formula: see text] higher than 70% and 90%. Under optimum conditions, the Yield[Formula: see text] andCPP[Formula: see text] of the AC-CoTAPc catalyst could be as high as 87.4% and 98.1%, with a purity[Formula: see text]of DMDS product of above 99.9%. AC-CoTAPc exhibits better catalytic and reuse performance than the commercial AC-supported sulphonated cobalt(II) phthalocyanine (AC-CoPcS) catalyst and shows broad industrial application prospects.

Preparation of Sulfated Zirconia-Modified Mesoporous SBA-15 and Catalytic Performance in Synthesis of Methyl Palmitate

2011 ◽  
Vol 233-235 ◽  
pp. 1714-1717 ◽  
Author(s):  
Zhi Ming Tian ◽  
Qi Gang Deng ◽  
Le Yuan Li
Keyword(s):  
Sulfated Zirconia ◽  
Molecular Sieves ◽  
Methyl Palmitate ◽  
Nitrogen Adsorption ◽  
Average Diameter ◽  
Catalytic Performance ◽  
Hexagonal Structure ◽  
Optimum Conditions ◽  
Hydrolysis Method ◽  
Orthogonal Experiments

Sulfated zirconia-modified mesoporous SBA-15 molecular sieves(ZS/SBA-15) had been prepared by homogeneous urea hydrolysis method. The modified materials were characterized by X-ray diffraction (XRD), transmission electron micrographs (TEM), nitrogen adsorption. XRD results exhibit that ZS/SBA-15 remains the highly order mesoporous channels with hexagonal structure. The average diameter of the pore decreases from 5.60 to 4.70 nm after addition of ZrO2and SO42-to SBA-15.The acid strength(0.80<H0<0.99)on catalyst surface was determined by mean of Hammett indication method, and the total amount of acid (1.42 mmol·g-1) was estimated by TPD of NH3. The catalyst (ZS/SBA-15) show best catalytic activity in synthesis of methyl palmitate.The optimum conditions of the esterification by orthogonal experiments were studied: the molar of methanol to palmitic acid 15: 1,the amount of catalyst 0.8 g, reaction time 8h .The conversion of methyl palmitate could reach 90.3% under the optimum conditions.

Thermal Inactivation at High Temperatures and Regeneration of Green Asparagus Peroxidase

1996 ◽  
Vol 59 (10) ◽  
pp. 1065-1071 ◽  
Author(s):  
CARMEN RODRIGO ◽  
MIGUEL RODRIGO ◽  
ANDRÉS ALVARRUIZ ◽  
ANA FRÍGOLA
Keyword(s):  
Enzyme Activity ◽  
Peroxidase Activity ◽  
Thermal Inactivation ◽  
Maximum Activity ◽  
Small Samples ◽  
Inactivation Kinetics ◽  
Optimum Conditions ◽  
First Order ◽  
Kinetics Of ◽  
Green Asparagus

A spectrophotometric method was developed for determining the peroxidase activity of green asparagus in small samples. The optimum conditions for the analysis in the cuvette were 45 mM of H2O2 36 mM of guaiacol, and pH 7. The method can be used to determine enzyme activity at up to two decimal reductions. A study was performed of the regeneration and inactivation kinetics of the enzyme when heated between 90 and 125°C. Regenerated asparagus peroxidase reached its maximum activity after being stored 6 days at 25°C. The regenerated enzyme followed first-order inactivation kinetics, showing an Ea = 13.62 kcal/mol and k100°C = 2.07 min−1.

scholarly journals Gold Nanoparticles Supported on Urchin-Like CuO: Synthesis, Characterization, and Their Catalytic Performance for CO Oxidation

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 67 ◽  
Author(s):  
Feng Dong ◽  
Yuan Guo ◽  
Dongyang Zhang ◽  
Baolin Zhu ◽  
Weiping Huang ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Co Oxidation ◽  
Solution Method ◽  
Catalytic Mechanism ◽  
Gold Catalysts ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
Metallic State ◽  
Reaction Cycles ◽  
Cuo Microspheres

Gold catalysts have been studied in-depth due to their unique activities for catalytic CO oxidation. Supports have intrinsic motivation for the high activity of gold catalysts. Thermally stable urchin-like CuO microspheres, which are potential support for gold catalysts, were prepared by facile solution-method. Then gold nanoparticles were loaded on them by deposition-precipitation method. The obtained gold catalysts were characterized by SEM, XRD, TEM, BET, ICP, and XPS. Their catalytic activity for CO oxidation was also evaluated. TEM results revealed that the gold nanoparticles with small sizes were highly distributed on the CuO surface in Au1.0/CuO-300. XPS observations demonstrated that the gold species in Au1.0/CuO-300 was of metallic state. Among the as-prepared catalysts, the Au1.0/CuO-300 catalyst displayed the best performance for CO oxidation and achieved 100% CO oxidation at 80 °C. It kept 100% conversion for 20 h at a reaction temperature of 180 °C, and showed good reusability after three reaction-cycles. The possible catalytic mechanism of Au1.0/CuO-300 catalyst for CO oxidation was also briefly proposed.

Tissue and Bacterial Splitting of Sulphasalazine

1983 ◽  
Vol 64 (3) ◽  
pp. 349-354 ◽  
Author(s):  
A. K. Azad Khan ◽  
Glynis Guthrie ◽  
H. H. Johnston ◽  
S. C. Truelove ◽  
D. H. Williamson
Keyword(s):  
Azo Dyes ◽  
Enzyme System ◽  
Reductase Activity ◽  
Maximum Activity ◽  
The Other ◽  
Optimum Conditions ◽  
Anaerobic Conditions ◽  
Azo Reductase ◽  
Tissue Homogenates

1. The cleavage of sulphasalazine at the azo bond by bacterial suspensions and tissue homogenates has been studied in vitro. 2. For maximum activity the azo reductase system requires anaerobic conditions and the presence of cofactors, namely NADPH and FAD. in this respect, sulphasalazine resembles other azo dyes. 3. Under optimum conditions all the species of bacteria tested were capable of splitting sulphasalazine and there were no major differences in the degree of activity shown by different species. The enzyme system is located within the bacterial cell and does not leak out of it. 4. All the tissues tested, both human and rat, showed azo reductase activity. The liver showed a much higher activity than the other tissues.

scholarly journals Optimum conditions for Biomass and lytic enzyme production by Saccharomyces cerevisiae and removal of total solids from waste water of dairy processing

2013 ◽  
Vol 7 (3) ◽  
pp. 61-73
Author(s):  
Nadhem H. Hayder ◽  
Lamees M. R. Abbas ◽  
Reem Waled
Keyword(s):  
Waste Water ◽  
Suspended Solids ◽  
Maximum Activity ◽  
Lytic Enzyme ◽  
Optimum Conditions ◽  
Lytic Enzymes ◽  
Total Solids ◽  
Maximum Reduction ◽  
Yeast Biomass ◽  
Dairy Waste

The present study was aimed to study the optimum conditions of producing yeast biomass and lytic enzymes, and removal of total solids from dairy waste water. Results showed that dairy waste water serve as a good substrate, enabling the growth of Saccharomyces cerevisia S4, which produced a considerable amount of yeast biomass. Maximum production of biomass was 26g/l obtained after 96h fermentation, at pH6, temperature 30°C and dairy waste concentration of 2.5% w/v. The maximum activity of α-amylase and protease were (67.7, 60.2)U/mg, respectively obtained when cultured the yeast in dairy waste water 2.5%w/v at pH6 and incubated for 120h at 30°C. The maximum reduction of total suspended solids and total dissolved solids were (44.1,53.6)% respectively observed after 96h of fermentation period at 30°C.

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