It is likely that immobilization by covalent bonding
caused conformational changes in the three-dimensional structure of the enzyme, which hindered substrate access to the immobilized enzyme active site, consequently reducing the maximum reaction speed when compared with the free lipase (Hiol et al., 2000; Yang et al., 2010).
The enzyme immobilization in sol-gel matrix was performed by physical adsorption and covalent bonding
according to methodology by Soares et al.
Emilio Sanchez, spokesman for ForeignTRADEX serving New Mexico, Arizona, Texas and Colorado regions said the website can be used to find direct and indirect suppliers of most types of chemicals such as element of compound based chemicals, including metal, nonmetal, metallic, covalent bonding
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Specific topics include the synthesis and characterization of new fluorinated polymides, imidization of polyester-amine salt precursors to polymides, liquid crystalline structures and crystallization morphology in aromatic bismides and their blends with semicrystalline polymide, Ceramide materials for advanced high-performance and high-temperature applications, polymide matrices for carbon-to-carbon composites with turbostatic structures, molecular assembly of polymides and oligoimides with direct covalent bonding
, and electroless metallization of polymides.
Atomic structure, valence electrons, and covalent bonding
We also found that covalent bonding
of the treatment chemical to silica is preferred to just associative, i.e., hydrogen bonding.
The first volume focuses on fundamental aspects of chemical bonding, and presents such perspectives as the physical origin of covalent bonding
, the natural bond orbital (NBO) view, the valence bond perspective, the conceptual density functional theory, and relativity and chemical bonding.
Although these IR spectra themselves do not provide direct evidence for any covalent bonding
between the PNIPA hydrogel and modified silica, the results indicating the presence of ester carbonyl groups in the absence of any double bonds in the PNIPA/modified silica hydrogel suggested that the double bonds introduced on the modified silica were copolymerized with NIPA and that the modified silica was bound with PNIPA hydrogel via covalent bonding
To estimate the extent of covalent bonding
between the polymer and inorganic particles, the nanocomposite samples were extracted with THF for 7 days using a Sohxlet extractor.
4 indicates that alternating copolymer poly(styrene-maleic anhydride) (SMA) is successfully grafted onto the surface of the silica nanoparticles through covalent bonding
. The absorption band at 1720 c[m.sup.-1] in the IR spectrum is a characteristic band of [v.sub.> c=o].
The adhesion enhancement of the Cu/pp-GMA-HDPE assemblies in the presence of Ar plasma pre-activation of the HDPE substrate was attributed to the covalent bonding
of the plasma-polymerized GMA (pp-GMA) layer with the HDPE surface, the preservation of the epoxide functional groups in the pp-GMA layer, and the spatial interactions of pp-GMA chains with the evaporated Cu matrix.