scholarly journals The Study of Laccase Immobilization Optimization and Stability Improvement on CTAB-KOH Modified Biochar

2021 ◽  
Author(s):  
Zhaobo Wang ◽  
Dajun Ren ◽  
Shan Jiang ◽  
Hongyan Yu ◽  
Yaohui Cheng ◽  
...  
Keyword(s):  
Enzyme Stability ◽  
Kinetic Studies ◽  
Relative Activity ◽  
Industrial Applications ◽  
Common Method ◽  
Adsorption Method ◽  
Experimental Conditions ◽  
K Value ◽  
Modified Biochar ◽  
Laccase Immobilization

Abstract Background: Although laccase has a good catalytic oxidation ability, free laccase shows a poor stability. Enzyme immobilization is a common method to improve enzyme stability and endow the enzyme with reusability. Adsorption is the simplest and common method. Modified biochar has attracted great attention due to its excellent performance. Results: In this paper, cetyltrimethylammonium bromide (CTAB)-KOH modified biochar (CKMB) was used to immobilize laccase by adsorption method (laccase@CKMB). Based on the results of the single-factor experiments, the optimal loading conditions of laccase@CKMB were studied with the assistance of Design-Expert 12 and response surface methods. The predicted optimal experimental conditions were laccase dosage 1.78 mg/mL, pH 3.1 and 312 K. Under these conditions, the activity recovery of laccase@CKMB was the highest, reaching 61.78 %. Then, the CKMB and laccase@CKMB were characterized by TGA, FT-IR, XRD, BET and SEM, and the results showed that laccase could be well immobilized on CKMB, the maximum enzyme loading could reach 57.5 mg/g. Compared to free laccase, the storage and pH stability of laccase@CKMB was improved greatly. The laccase@CKMB retained about 40 % of relative activity (4 ℃, 30 days) and more than 50 % of relative activity at pH 2-6. In addition, the laccase@CKMB indicated the reusability up to 6 reaction cycles while retaining 45.1 % of relative activity. Moreover, the thermal deactivation kinetic studies of laccase@CKMB showed a lower k value (0.00275 min-1) and higher t1/2 values (252.0 min) than the k value (0.00573 min-1) and t1/2 values (121.0 min) of free laccase. Conclusions: We explored scientific and reasonable immobilization conditions of laccase@CKMB, and the laccase@CKMB possessed relatively better stabilities, which gave the immobilization of laccase on this cheap and easily available carrier material the possibility of industrial applications.

scholarly journals The study of laccase immobilization optimization and stability improvement on CTAB-KOH modified biochar

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Zhaobo Wang ◽  
Dajun Ren ◽  
Shan Jiang ◽  
Hongyan Yu ◽  
Yaohui Cheng ◽  
...  
Keyword(s):  
Enzyme Stability ◽  
Kinetic Studies ◽  
Relative Activity ◽  
Industrial Applications ◽  
Common Method ◽  
Adsorption Method ◽  
Experimental Conditions ◽  
K Value ◽  
Modified Biochar ◽  
C 30

Abstract Background Although laccase has a good catalytic oxidation ability, free laccase shows a poor stability. Enzyme immobilization is a common method to improve enzyme stability and endow the enzyme with reusability. Adsorption is the simplest and common method. Modified biochar has attracted great attention due to its excellent performance. Results In this paper, cetyltrimethylammonium bromide (CTAB)-KOH modified biochar (CKMB) was used to immobilize laccase by adsorption method (laccase@CKMB). Based on the results of the single-factor experiments, the optimal loading conditions of laccase@CKMB were studied with the assistance of Design-Expert 12 and response surface methods. The predicted optimal experimental conditions were laccase dosage 1.78 mg/mL, pH 3.1 and 312 K. Under these conditions, the activity recovery of laccase@CKMB was the highest, reaching 61.78%. Then, the CKMB and laccase@CKMB were characterized by TGA, FT-IR, XRD, BET and SEM, and the results showed that laccase could be well immobilized on CKMB, the maximum enzyme loading could reach 57.5 mg/g. Compared to free laccase, the storage and pH stability of laccase@CKMB was improved greatly. The laccase@CKMB retained about 40% of relative activity (4 °C, 30 days) and more than 50% of relative activity at pH 2.0–6.0. In addition, the laccase@CKMB indicated the reusability up to 6 reaction cycles while retaining 45.1% of relative activity. Moreover, the thermal deactivation kinetic studies of laccase@CKMB showed a lower k value (0.00275 min− 1) and higher t1/2 values (252.0 min) than the k value (0.00573 min− 1) and t1/2 values (121.0 min) of free laccase. Conclusions We explored scientific and reasonable immobilization conditions of laccase@CKMB, and the laccase@CKMB possessed relatively better stabilities, which gave the immobilization of laccase on this cheap and easily available carrier material the possibility of industrial applications.

scholarly journals The Study of Laccase Immobilization Optimization and Stability Improvement on CTAB-KOH Modified Biochar

2021 ◽  
Author(s):  
Zhaobo Wang ◽  
Dajun Ren ◽  
Zihang Li ◽  
Hongyan Yu ◽  
Shuqin Zhang ◽  
...  
Keyword(s):  
Kinetic Studies ◽  
Relative Activity ◽  
Industrial Applications ◽  
Adsorption Method ◽  
Experimental Conditions ◽  
K Value ◽  
Modified Biochar ◽  
Ft Ir ◽  
Laccase Immobilization ◽  
Reaction Cycles

Abstract Background: In this paper, cetyltrimethylammonium bromide (CTAB)-KOH modified biochar (CKMB) was used to immobilize laccase by adsorption method (laccase@CKMB). Based on the results of the single-factor experiments, the optimal loading conditions of laccase@CKMB were studied with the assistance of Design-Expert 12 and response surface methods. Results: The predicted optimal experimental conditions were laccase dosage 1.78 mg/mL, pH 3.1 and 312 K. Under these conditions, the activity recovery of laccase@CKMB was the highest, reaching 61.78 %. Then, the CKMB and laccase@CKMB were characterized by TGA, FT-IR, XRD, BET and SEM, and the results showed that laccase could be well immobilized on CKMB, the maximum enzyme loading could reach 57.5 mg/g. Compared to free laccase, the storage and pH stability of laccase@CKMB was improved greatly. The laccase@CKMB retained about 40 % of relative activity (4 ℃, 30 days) and more than 50 % of relative activity at pH 2-6. In addition, the laccase@CKMB indicated the reusability up to 6 reaction cycles while retaining 45.1 % of relative activity. Moreover, the thermal deactivation kinetic studies of laccase@CKMB showed a lower k value (0.00275 min-1) and higher t1/2 values (252.0 min) than the k value (0.00573 min-1) and t1/2 values (121.0 min) of free laccase. Conclusions: In summary, we explored scientific and reasonable immobilization conditions of laccase@CKMB, and the laccase@CKMB possessed relatively better stabilities, which gave the immobilization of laccase on this cheap and easily available carrier material the possibility of industrial applications.

scholarly journals α-Cellulose Fibers of Paper-Waste Origin Surface-Modified with Fe3O4 and Thiolated-Chitosan for Efficacious Immobilization of Laccase

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 581
Author(s):  
Gajanan S. Ghodake ◽  
Surendra K. Shinde ◽  
Ganesh D. Saratale ◽  
Rijuta G. Saratale ◽  
Min Kim ◽  
...  
Keyword(s):  
Enzyme Immobilization ◽  
Photoelectron Spectroscopy ◽  
Cellulose Fibers ◽  
Relative Activity ◽  
Significant Activity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Laccase Immobilization ◽  
Surface Modified

The utilization of waste-paper-biomass for extraction of important α-cellulose biopolymer, and modification of extracted α-cellulose for application in enzyme immobilization can be extremely vital for green circular bio-economy. Thus, in this study, α-cellulose fibers were super-magnetized (Fe3O4), grafted with chitosan (CTNs), and thiol (-SH) modified for laccase immobilization. The developed material was characterized by high-resolution transmission electron microscopy (HR-TEM), HR-TEM energy dispersive X-ray spectroscopy (HR-TEM-EDS), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) analyses. Laccase immobilized on α-Cellulose-Fe3O4-CTNs (α-Cellulose-Fe3O4-CTNs-Laccase) gave significant activity recovery (99.16%) and laccase loading potential (169.36 mg/g). The α-Cellulose-Fe3O4-CTNs-Laccase displayed excellent stabilities for temperature, pH, and storage time. The α-Cellulose-Fe3O4-CTNs-Laccase applied in repeated cycles shown remarkable consistency of activity retention for 10 cycles. After the 10th cycle, α-Cellulose-Fe3O4-CTNs possessed 80.65% relative activity. Furthermore, α-Cellulose-Fe3O4-CTNs-Laccase shown excellent degradation of pharmaceutical contaminant sulfamethoxazole (SMX). The SMX degradation by α-Cellulose-Fe3O4-CTNs-Laccase was found optimum at incubation time (20 h), pH (3), temperatures (30 °C), and shaking conditions (200 rpm). Finally, α-Cellulose-Fe3O4-CTNs-Laccase gave repeated degradation of SMX. Thus, this study presents a novel, waste-derived, highly capable, and super-magnetic nanocomposite for enzyme immobilization applications.

Heat Transfer and Pressure Drop for Flow Boiling of Water in Narrow Vertical Rectangular Channels

2003 ◽  
Author(s):  
Jianyun Shuai ◽  
Rudi Kulenovic ◽  
Manfred Groll
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Boiling ◽  
Bubbly Flow ◽  
High Heat ◽  
Flow Patterns ◽  
Industrial Applications ◽  
Heat Fluxes ◽  
Experimental Conditions ◽  
Rectangular Channels

Flow boiling in small-sized channels attracted extensive investigations in the past two decades due to special requirements for transfer of high heat fluxes from narrow spaces in various industrial applications. Experiments on various aspects of flow boiling in narrow channels were carried out and theoretical attempts were undertaken. But these investigations showed large differences, e.g. up till now the knowledge on the development of flow patterns in small non-circular flow passages is very limited. This paper deals with investigations on flow boiling of water in two rectangular channels with dimensions (width×depth) 2.0×4.0 mm2 and 0.5×2.0 mm2 (corresponding hydraulic diameters are 2.67 mm and 0.8 mm). The pressure at the test section exit is atmospheric. For steady-state experimental conditions the effects of heat flux, mass flux and inlet subcooling on the boiling heat transfer coefficient and the pressure drop are investigated. Flow patterns and the transition of flow patterns along the channel axis are visualized and documented with a video-camera. Bubbly flow, slug flow and annular flow are distinguished in both channels. Preliminary flow pattern maps are generated.

scholarly journals Fault Diagnosis of Rotating Machinery under Noisy Environment Conditions Based on a 1-D Convolutional Autoencoder and 1-D Convolutional Neural Network

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 972 ◽  
Author(s):  
Xingchen Liu ◽  
Qicai Zhou ◽  
Jiong Zhao ◽  
Hehong Shen ◽  
Xiaolei Xiong
Keyword(s):  
Neural Network ◽  
Fault Diagnosis ◽  
Convolutional Neural Network ◽  
Industrial Applications ◽  
Experimental Result ◽  
Noisy Environment ◽  
Experimental Conditions ◽  
Global Average ◽  
Noisy Input ◽  
Convolutional Autoencoder

Deep learning methods have been widely used in the field of intelligent fault diagnosis due to their powerful feature learning and classification capabilities. However, it is easy to overfit depth models because of the large number of parameters brought by the multilayer-structure. As a result, the methods with excellent performance under experimental conditions may severely degrade under noisy environment conditions, which are ubiquitous in practical industrial applications. In this paper, a novel method combining a one-dimensional (1-D) denoising convolutional autoencoder (DCAE) and a 1-D convolutional neural network (CNN) is proposed to address this problem, whereby the former is used for noise reduction of raw vibration signals and the latter for fault diagnosis using the de-noised signals. The DCAE model is trained with noisy input for denoising learning. In the CNN model, a global average pooling layer, instead of fully-connected layers, is applied as a classifier to reduce the number of parameters and the risk of overfitting. In addition, randomly corrupted signals are adopted as training samples to improve the anti-noise diagnosis ability. The proposed method is validated by bearing and gearbox datasets mixed with Gaussian noise. The experimental result shows that the proposed DCAE model is effective in denoising and almost causes no loss of input information, while the using of global average pooling and input-corrupt training improves the anti-noise ability of the CNN model. As a result, the method combined the DCAE model and the CNN model can realize high-accuracy diagnosis even under noisy environment.

scholarly journals Optimization, equilibrium and kinetic studies of Zn2+ and Ni2+ adsorption from aqueous solutions using composite adsorbent

2018 ◽  
Vol 67 (3) ◽  
pp. 279-290 ◽  
Author(s):  
Haider M. Zwain ◽  
Mohammadtaghi Vakili ◽  
Irvan Dahlan
Keyword(s):  
Contact Time ◽  
Coal Fly Ash ◽  
Sol Gel ◽  
Freundlich Isotherm ◽  
Kinetic Studies ◽  
Isotherm Models ◽  
Experimental Conditions ◽  
Palm Oil Fuel Ash ◽  
Composite Adsorbent ◽  
Oil Fuel

Abstract A novel RHA/PFA/CFA composite adsorbent was synthesized from rice husk ash (RHA), palm oil fuel ash (PFA), and coal fly ash (CFA) by modified sol-gel method. Effect of different parameters such as adsorbent dosage, contact time, and pH were studied using batch experiment to optimize the maximum zinc (Zn2+) and nickel (Ni2) adsorption conditions. Results showed that the maximum adsorption condition occurred at adsorbent amount of 10 g/L, contact time of 60 min, and pH 7. At this condition, the removal efficiencies were 81% and 61% for Zn2+ and Ni2+, in which the adsorption capacities (qmax) were 21.74 mg/g and 17.85 mg/g, respectively. Adsorption behavior of RHA/PFA/CFA composite adsorbent was studied through the various isotherm models at different adsorbent amounts. The results indicated that the Freundlich isotherm model gave an excellent agreement with the experimental conditions. Based on the results obtained from the kinetic studies, pseudo-second-order was suitable for the adsorption of Ni2+ and Zn2+, compared to the pseudo-first-order model. The results presented in this study showed that RHA/PFA/CFA composite adsorbent successfully adsorbed Zn2+ and Ni2.

scholarly journals Be Aware of Aggregators in the Search for Potential Human ecto-5′-Nucleotidase Inhibitors

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 1876 ◽  
Author(s):  
Lucas Viviani ◽  
Erika Piccirillo ◽  
Arquimedes Cheffer ◽  
Leandro de Rezende ◽  
Henning Ulrich ◽  
...  
Keyword(s):  
Drug Discovery ◽  
Kinetic Studies ◽  
Enzyme Concentration ◽  
Experimental Conditions ◽  
Time Aggregation ◽  
Compound C ◽  
Promising Target ◽  
Ic50 Values ◽  
Potential Inhibitors ◽  
Triton X

Promiscuous inhibition due to aggregate formation has been recognized as a major concern in drug discovery campaigns. Here, we report some aggregators identified in a virtual screening (VS) protocol to search for inhibitors of human ecto-5′-nucleotidase (ecto-5′-NT/CD73), a promising target for several diseases and pathophysiological events, including cancer, inflammation and autoimmune diseases. Four compounds (A, B, C and D), selected from the ZINC-11 database, showed IC50 values in the micromolar range, being at the same time computationally predicted as potential aggregators. To confirm if they inhibit human ecto-5′-NT via promiscuous mechanism, forming aggregates, enzymatic assays were done in the presence of 0.01% (v/v) Triton X-100 and an increase in the enzyme concentration by 10-fold. Under both experimental conditions, these four compounds showed a significant decrease in their inhibitory activities. To corroborate these findings, turbidimetric assays were performed, confirming that they form aggregate species. Additionally, aggregation kinetic studies were done by dynamic light scattering (DLS) for compound C. None of the identified aggregators has been previously reported in the literature. For the first time, aggregation and promiscuous inhibition issues were systematically studied and evaluated for compounds selected by VS as potential inhibitors for human ecto-5′-NT. Together, our results reinforce the importance of accounting for potential false-positive hits acting by aggregation in drug discovery campaigns to avoid misleading assay results.

The influence of experimental conditions on the assessment of the toxicity of 2,4-dichlorophenol to anaerobic degradative bacteria

2002 ◽  
Vol 45 (10) ◽  
pp. 61-63 ◽  
Author(s):  
N. Nitayapat ◽  
I.A. Watson-Craik
Keyword(s):  
Steady State ◽  
Incubation Temperature ◽  
Anaerobic Bacteria ◽  
Relative Activity ◽  
Experimental Conditions ◽  
Fermentative Bacteria ◽  
Two Temperatures

The toxicity of 2,4-dichlorophenol (2,4-DCP) to anaerobic bacteria in refuse cultures was investigated at two temperatures (30 and 37°C) and after two different exposure periods to the toxicants. It was shown that at 0.52mM 2,4-DCP the time of exposure of microorganisms to 2,4-DCP affected the relative activity (Av) of the production of methane. Av values at the beginning of the steady-state phase were lower than those recorded two weeks later. The incubation temperature selected also critically affected the assessment of anaerobic toxicity; at 37°C an imbalance of the activities of fermentative bacteria and acetogens with those of methanogens was observed.

scholarly journals Non-Precious Electrodes for Practical Alkaline Water Electrolysis

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1336 ◽  
Author(s):  
Alejandro N. Colli ◽  
Hubert H. Girault ◽  
Alberto Battistel
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Renewable Energy Sources ◽  
Water Electrolysis ◽  
Industrial Applications ◽  
Alkaline Water Electrolysis ◽  
Stainless Steel 316L ◽  
Experimental Conditions ◽  
Alkaline Water ◽  
Cell Components

Water electrolysis is a promising approach to hydrogen production from renewable energy sources. Alkaline water electrolyzers allow using non-noble and low-cost materials. An analysis of common assumptions and experimental conditions (low concentrations, low temperature, low current densities, and short-term experiments) found in the literature is reported. The steps to estimate the reaction overpotentials for hydrogen and oxygen reactions are reported and discussed. The results of some of the most investigated electrocatalysts, namely from the iron group elements (iron, nickel, and cobalt) and chromium are reported. Past findings and recent progress in the development of efficient anode and cathode materials appropriate for large-scale water electrolysis are presented. The experimental work is done involving the direct-current electrolysis of highly concentrated potassium hydroxide solutions at temperatures between 30 and 100 °C, which are closer to industrial applications than what is usually found in literature. Stable cell components and a good performance was achieved using Raney nickel as a cathode and stainless steel 316L as an anode by means of a monopolar cell at 75 °C, which ran for one month at 300 mA cm−2. Finally, the proposed catalysts showed a total kinetic overpotential of about 550 mV at 75 °C and 1 A cm−2.

Wear Quantification

1999 ◽  
Vol 122 (3) ◽  
pp. 650-656 ◽  
Author(s):  
A. Ravikiran
Keyword(s):  
Wear Rate ◽  
Material Properties ◽  
Industrial Applications ◽  
Improved Method ◽  
Experimental Conditions ◽  
General Consensus ◽  
Benchmark Tests ◽  
Pin On Disc ◽  
Improve Correlation ◽  
The Way

Tribology literature shows considerable scatter in the wear rate of materials obtained by pin-on-disc type of studies. The general consensus thus far has been that this scatter is due to variations in the material properties and experimental conditions used by different investigators. However, the present paper shows that the scatter can also arise from the way wear is quantified by popular methods such as by m3/m, m3/Nm and so on. Therefore, an improved method of wear quantification indicated as “wear index” (WI) a non-dimensional quantity, has been proposed and it is expected to reduce scatter that arises from the way wear is quantified. Evidence for the improvement has been provided from the results obtained from the experiments reported in this paper as well as those reported by different researchers. Besides reducing scatter, WI is expected to improve correlation in the wear values between laboratory benchmark tests and actual industrial applications, and also that between different investigators. Hence WI is expected to enhance the general understanding on tribology. [S0742-4787(00)01103-6]

Sign in / Sign up

Export Citation Format

Share Document