Microwave-Assisted Lipase Covalent Immobilization and Improved Its Thermal Stability Using Alcohols to Quench Excessive Activated Groups on Support Surface

2009 ◽  
Vol 42 (6) ◽  
pp. 441-446 ◽  
Author(s):  
Zhiqiang Du ◽  
Anming Wang ◽  
Cheng Zhou ◽  
Shemin Zhu ◽  
Shubao Shen
Keyword(s):  
Thermal Stability ◽  
Covalent Immobilization ◽  
Support Surface ◽  
Microwave Assisted

scholarly journals The influence of the nature and textural properties of different supports on the thermal behavior of Keggin type heteropolyacids

2006 ◽  
Vol 71 (3) ◽  
pp. 235-249 ◽  
Author(s):  
Alexandru Popa ◽  
Viorel Sasca ◽  
Mircea Stefanescu ◽  
Erne Kis ◽  
Radmila Marinkovic-Neducin
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Thermal Behavior ◽  
Solid Phase ◽  
Textural Properties ◽  
Nitrogen Adsorption ◽  
Active Phase ◽  
Support Surface ◽  
Sem Images ◽  
The Stability

In order to obtain highly dispersed heteropolyacids (HPAs) species, H3PMo12O40 and H4PVMo11O40 were supported on various supports: silica (Aerosil - Degussa and Romsil types) and TiO2. The structure and thermal decomposition of supported and unsupported HPAs were followed by different techniques (TGA-DTA, FTIR, XRD, low temperature nitrogen adsorption, scanning electron microscopy). All the supported HPAs were prepared by impregnation using the incipient wetness technique with a 1:1 mixture of water-ethanol. Samples were prepared with different concentrations to examine the effect of loading on the thermal behavior of the supported acid catalysts. The thermal stability was evaluated with reference to the bulk solid acids and mechanical mixtures. After deposition on silica types supports, an important decrease in thermal stability was observed on the Romsil types and a small decrease on the Aerosil type. The stability of the heteropolyacids supported on titania increased due to an anion-support interaction, as the thermal decomposition proceeded in two steps. The structure of the HPAs was not totally destroyed at 450 ?C as some IR bands were still preserved. A relatively uniform distribution of HPAs on the support surface was observed for all compositions of the active phase. No separate crystallites of solid phase HPAs were found in the SEM images.

scholarly journals Microwave-assisted synthesis of high thermal stability and colourless polyimides containing pyridine

2019 ◽  
Vol 6 (6) ◽  
pp. 190196 ◽  
Author(s):  
Kai Cheng ◽  
Jie-pin Hu ◽  
Yan-cheng Wu ◽  
Chu-qi Shi ◽  
Zhi-geng Chen ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Synthesis Method ◽  
Optical Transmittance ◽  
Aromatic Diamine ◽  
Microwave Assisted Synthesis ◽  
Step Method ◽  
Light Emitting ◽  
Microwave Assisted ◽  
One Step ◽  
Biphenyltetracarboxylic Dianhydride

A novel aromatic diamine containing pyridyl side group, 4-pyridine-4,4-bis(3,5-dimethyl-5-aminophenyl)methane (PyDPM), was successfully synthesized via electrophilic substitution reaction. The polyimides (PIs) containing pyridine were obtained via the microwave-assisted one-step polycondensation of the PyDPM with pyromellitic dianhydride (PMDA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3′,4,4′-diphenylether tetracarboxylic dianhydride (ODPA) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA). Contrarily to the reported similar PIs, these PIs exhibit much higher thermal stability or heat resistance, i.e. high glass transition temperatures ( T g s) in the range of 358–473°C, and the decomposition temperatures at 5% weight loss over 476°C under nitrogen. They can afford flexible and strong films with tensile strength of 82.1–93.3 MPa, elongation at break of 3.7%–15.2%, and Young's modulus of 3.3–3.8 GPa. Furthermore, The PI films exhibit good optical transparency with the cut-off wavelength at 313–366 nm and transmittance higher than 73% at 450 nm. The excellent thermal and optical transmittance can be attributed to synthesis method and the introduction of pyridine rings and ortho-methyl groups. The inherent viscosities of PIs via one-step method were found to be 0.58–1.12 dl g −1 in DMAc, much higher than those via two-step method. These results indicate these PIs could be potential candidates for optical substrates of organic light emitting diodes (OLEDs).

Immobilization of modified penicillin G acylase on Sepabeads carriers

2009 ◽  
Vol 63 (2) ◽  
Author(s):  
Milena Žuža ◽  
Nenad Milosavić ◽  
Zorica Knežević-Jugović
Keyword(s):  
Thermal Stability ◽  
Hydrolytic Activity ◽  
Covalent Immobilization ◽  
Stability Study ◽  
Penicillin G Acylase ◽  
Penicillin G ◽  
Chemically Modified ◽  
Modified Enzyme ◽  
Derivatives Of ◽  
Thermal Stability Study

AbstractAn approach to stable covalent immobilization of chemically modified penicillin G acylase from Escherichia coli on Sepabeads® carriers with high retention of hydrolytic activity and thermal stability is presented. The two amino-activated polymethacrylate particulate polymers with different spacer lengths used in the study were Sepabeads® EC EA and Sepabeads® EC HA. The enzyme was first modified by cross-linking with polyaldehyde derivatives of starch in order to provide it with new useful functions. Such modified enzyme was then covalently immobilized on amino supports. The method seems to provide a possibility to couple the enzyme without risking a reaction at the active site which might cause the loss of activity. Performances of these immobilized biocatalysts were compared with those obtained by the conventional method with respect to activity and thermal stability. The thermal stability study shows that starch-PGA immobilized on Sepabeads EC-EA was almost 4.5-fold more stable than the conventionally immobilized one and 7-fold more stable than free non-modified PGA. Similarly, starch-PGA immobilized on Sepabeads EC-HA was around 1.5- fold more stable than the conventionally immobilized one and almost 9.5-fold more stable than free non-modified enzyme.

Improving thermal stability of KSrPO4:Tb3+ phosphors prepared by microwave assisted sintering

2013 ◽  
Vol 35 (12) ◽  
pp. 2102-2106 ◽  
Author(s):  
Yu-Ming Peng ◽  
Yan-Kuin Su ◽  
Ru-Yuan Yang
Keyword(s):  
Thermal Stability ◽  
Microwave Assisted ◽  
Thermal Stability Of

Fabrication of a magnetic nanoparticle embedded NH2-MIL-88B MOF hybrid for highly efficient covalent immobilization of lipase

RSC Advances ◽  
2016 ◽  
Vol 6 (71) ◽  
pp. 66385-66393 ◽  
Author(s):  
Arpita Samui ◽  
Angshuman Ray Chowdhuri ◽  
Triveni Kumar Mahto ◽  
Sumanta Kumar Sahu
Keyword(s):  
Thermal Stability ◽  
Magnetic Nanoparticle ◽  
Immobilized Lipase ◽  
Metal Organic Framework ◽  
Covalent Immobilization ◽  
Lipase Immobilization ◽  
Highly Efficient ◽  
Amine Functionalized ◽  
Magnetic Metal ◽  
Metal Organic

We demonstrate an approach to synthesize an amine-functionalized magnetic metal-organic framework (MOF) for lipase immobilization. The activity of immobilized lipase is enhanced by different parameters like pH, temperature and thermal stability.

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