Covalent Immobilization of Subtilisin A onto Thin Films of Maleic Anhydride Copolymers

Enzymes cleaving the biopolymer adhesives of fouling organisms are attracting attention for the prevention of biofouling. We report a versatile and robust method to confine the serine protease Subtilisin A (or Subtilisin Carlsberg) to surfaces to be protected against biofouling. The approach consists of the covalent immobilization of the protease onto maleic anhydride copolymer thin film coatings. High‐swelling poly(ethylene‐alt‐maleic anhydride) (PEMA) copolymer layers permitted significantly higher enzyme loadings and activities than compact poly(octadecene‐alt‐maleic anhydride) (POMA) films. Substantial fractions of the immobilized, active enzyme layers were found to be conserved upon storage in deionized water for several hours. Ongoing studies explore the potentialities of the developed bioactive coatings to reduce the adhesion of various fouling organisms.

     

1H NMR assignment of oligomeric grafts of maleic anhydride‐grafted polyolefin

The ¹ H NMR assignment of oligomeric grafts of maleic anhydride (MA)‐grafted polyolefin (PO), MA‐g‐PO hereafter, was experimentally demonstrated for the first time using NMR spectroscopy. ¹³ C DEPT, ¹ H‐¹ H DQF‐COSY, and ¹ H T₂‐edited spectroscopy of MA‐g‐PO proved that peaks of the intermediate methine protons of succinic anhydride oligomeric grafts, which are nearly tetrameric, are observed at 2.5–3.5 ppm and show broadening. Copyright © 2012 John Wiley & Sons, Ltd.     

Influence of the Comonomer on the Dissociation of Some Alternating Maleic Acid Copolymers

Five alternating copolymers of maleic acid with N-vinylpyrrolidone, vinyl acetate, styrene, 2-vinylnaphthalene, and vinyl cyclohexane were used in order to study the influence of the comonomer on the polyelectrolyte behavior. The dissociation of the maleic acid copolymers was investigated by electrochemical methods in pure water and in the presence of supporting electrolytes. The conformational modifications during the dissociation were directly investigated by viscosimetry and fluorescence probing. The shape of the potentiometric and conductometric titration curves was influenced by the comonomer structure. In salt-free solution, only the first dissociation step was observed. The addition of univalent counterions permitted the evidencing of the second ionization step only for the copolymers with hydrophilic comonomers, but the addition of divalent counterions permitted the evidencing of the second ionization step for all five copolymers. The apparent dissociation constants increase with the increase of the comonomer hydrophobicity. A conformational transition was evidenced especially in the case of the maleic acid-2-vinylnaphthalene copolymer.     

Effect of maleic anhydride and liquid natural rubber as compatibilizers on the mechanical properties and impact resistance of the NR‐NBR blend

The degree of compatibilization between natural rubber (NR) and acrylonitrile‐butadiene rubber (NBR) was investigated by two different methods. NBR was chemically modified with maleic anhydride in a screw twin mixer with and without reaction initiator, benzoyl peroxide. Also, the effects of molecular weight of liquid natural rubber (LNR) as a compatibilizer were studied. The degree of compatibilization between NBR and NR is determined indirectly through measurements of mechanical properties and impact resistance. The maleic anhydride and benzoyl peroxide concentrations influence the mechanical properties and impact resistance of the blends. Also, the mechanical properties of the blends showed that the molecular weight of LNR played an important role in determing their performance. Copyright © 2004 John Wiley & Sons, Ltd.     

Diphenylarsinoderivate des Maleinsäureanhydrids und verwandte Verbindungen. Kristall- und Molekülstruktur des 2,3-Bis(diphenylstibino)maleinsäureanhydrids

The unusual properties of bis(diphenylphosphino)maleic anhydride and similar ditertiary phosphines has prompted the synthesis of analogous arsines and stibines. Bis(diphenylarsino)maleic anhydride,-maleic thioanhydride and-N-methyl maleic imide, bis(diphenylstibino)maleic anhydride (5) and-maleic thioanhydride are obtained as crystalline yellow or red compounds by the reaction of the corresponding 2,3-dichloromaleic acid derivatives with diphenyl(trimethylsilyl)arsine and-stibine resp. The uv/vis spectra and characteristic i.r. bands of selected compounds are given and compared with those of the corresponding phosphines. The strong shift of _C=C to lower wavenumbers observed in all compounds has caused the determination of crystal and molecular structure of5 by x-ray diffraction. Bond distances and angles are given. The complex formation of the new diarsine ligands has been examined by the preparation of Ni-, Cr- and Mo-carbonyl derivatives. As the first organylsulfane substituted maleic acid derivatives bis(phenylthio)maleic thioanhydride,-N-methyl-maleic imide and-maleic acid dimethylester are synthesized and described.

     

Effect of Cr and Co Promoters Addition on Vanadium Phosphate Catalysts for Mild Oxidation of n-Butane

In this study, Cr and Co promoted, as well as unpromoted vanadium phosphate (VPO) catalysts were synthesized by the reaction of V2O5 and o-H3PO4 in organic medium followed by calcination in n-butane/air environment at 673 K. The physico-chemical properties and the catalytic behavior were affected by the addition of Cr and Co dopants. H2-TPR was used to investigate the nature of oxidants in the unpromoted and promoted catalysts. The results showed that both the Cr and Co promoters remarkably lowered the temperature of the reduction peak associated with V5 . The amount of oxygen species originated from the active phase, V4 , removed was significantly increased for Co and Cr-promoted catalysts. Both Cr and Co dopants improve strongly the n-butane conversion without sacrificing the MA selectivity. A good correlation was observed between the amount of oxygen species removed from V4 phase and the activity for n-butane oxidation to maleic anhydride. This suggested that V4 -O was the center for the activation of n-butane.     

3-氨丙基三乙氧基硅烷对溶胶-凝胶法苯乙烯-顺丁烯二酸酐共聚物/SiO_2杂化材料的制备与性能的影响

用３ 氨丙基三乙氧基硅烷（ＡＰＴＥＳ）作为偶联剂，通过溶胶 凝胶（Ｓｏｌ Ｇｅｌ）过程制得两相以共价键结合的透明苯乙烯 顺丁烯二酸酐共聚物／ＳｉＯ２杂化材料．通过ＦＴＩＲ分析等证实了材料有机相与无机相间是以共价键结合的．分析了材料热处理温度和分别用盐酸或氨水作催化剂时对材料溶胶分数的影响、偶联剂及其用量对溶胶 凝胶体系凝胶时间的影响、并研究了杂化材料中无机含量对材料折射率和Ｔｇ的影响     

pH/temperature - sensitive imprinted ionic poly(N-tert-butylacrylamide-co-acrylamide/maleic acid) hydrogels for bovine serum albumin

In this study, we have prepared pH/temperature-sensitive imprinted ionic poly(N-tert-butylacrylamide-co-acrylamide/maleic acid) [P(TBA-co-AAm/MA)] hydrogels for bovine serum albumin (BSA) by using molecular imprinting method. BSA adsorption from aqueous BSA solutions was investigated with two types of hydrogel systems prepared by non-imprinted and imprinted methods. Hydrogels imprinted with BSA showed higher adsorption capacity and specificity for BSA than hydrogels prepared by the usual procedure. At all studied conditions, the highest BSA adsorption was observed in the hydrogel imprinted with 8.63 wt.-% BSA. In addition, the imprinted hydrogels exhibited both for good selectivity BSA and high adsorption rate depending on the number of BSA-sized cavities. Adsorption studies showed that other stimuli, such as pH, temperature and initial BSA concentration also influenced the BSA adsorption capacity of both non-imprinted and imprinted hydrogels.     

Crystal structure of triaquamaleatostrontium(II) monohydrate, [Sr(C4H2O4)(OH2)3]·H2O

[Sr(C₄H₂O₄)(OH₂)₃]·H₂O is monoclinic, P2₁/n, witha=11.476(2),b=7.027(1),c=12.344(2) Å, =115.74(3)°,V=896.67 ų,Z=4. The Sr atom is surrounded by nine oxygen atoms which come from four different maleate anions and three water molecules. The Sr–O distances range from 2.546(2) to 2.808(2) Å. The C–O distances are equal within the standard deviation 1.263(3) to 1.258(3) Å). In the maleate anion, the planes that contain the carboxylate groups form an angle of 74.44(9)°. Both carboxylate groups deviate significantly from planarity. The different coordination modes of the carboxylate group and the extensive hydrogen bonding present are responsible for the polymeric nature of the structure.