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901.
Alina I. Chiriac Francisco I. Javier Pastor Valentin I. Popa Magdalena Aflori Diana Ciolacu 《Cellulose (London, England)》2014,21(1):203-219
A newly identified cellulase with a high polysaccharide degrading potential and a processive mode of action, has been evaluated on cellulose fibers. Cellulase Cel9B from Paenibacillus barcinonensis is a modular endoglucanase with the domain structure GH9-CBM3c-Fn3-CBM3b, consisting of a family nine catalytic module GH9, an auxiliary module CBM3c, a fibronectin-like module Fn3, and a functional cellulose binding module CBM3b. The whole cellulase Cel9B (E1) and two truncated forms of the enzyme that consist of the catalytic module linked to the auxiliary module, GH9-CBM3c (E2), and of the cellulose binding module of the enzyme, CBM3b (CBD), were applied to softwood dissolving pulp. The changes in the supramolecular structure and morphology of the fibres after the enzymatic treatment were evaluated by viscosimetry, X-ray diffraction (XRD), thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy (SEM). XRD studies provided the crystallite size, interplanar distances and crystallinity index of the samples before and after the enzymatic treatment. The treatment with cellulases E1 and E2 decreased the degree of polymerization and increased the crystallinity index of the pulp. Both E1 and E2 had a pronounced capacity for removing fuzz and improved the smoothness and surface appearance of the fibers, as shown by SEM. On the other hand, CBD proved to be less effective under the tested conditions. Moreover, the solubility of dissolving pulp in alkaline solutions has been evaluated as an indirect measure of cellulose accessibility. A notable enhancement in alkaline solubility of the samples treated with the cellulases was observed. 相似文献
902.
Polycyclic aromatic hydrocarbons as test probes to investigate the retention behavior of 1,3‐alternate calix[4]arene silica‐bonded stationary phases
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A series of polycyclic aromatic hydrocarbons (PAHs) of different size and shape has been used to characterize the chromatographic behavior of five calix[4]arene stationary phases in 1,3‐alternate conformation synthesized in our laboratory. The selection of linear, four‐ring nonlinear, and five‐ring PAHs gave data on selectivity changes across range of the calix[4]arene columns. Retention of the 12 aromatic solutes has been evaluated at various methanol contents in the mobile phase (70–100% v/v) and column temperatures (20–45°C). The thermodynamic parameters underlying the retention mechanisms revealed that each of the five calix[4]arene columns exhibited variation in selectivity and retention of PAHs caused by enthalpy and entropy effects. The calixarene stationary phases substituted with electron‐withdrawing groups exhibit enhanced selectivity toward PAHs in comparison to the rest of the investigated columns. The observed divergences are due to differences in solute–stationary phase interactions and originate in π–π and π‐electron transfer specific to the analytes and the type of calix[4]arene functionalization at the upper rim, as well as steric and sorption phenomena. 相似文献
903.
H. Ümit Kaniskan Magdalena M. Szewczyk Zhengtian Yu Mohammad S. Eram Xiaobao Yang Keith Schmidt Xiao Luo Miao Dai Feng He Irene Zang Ying Lin Steven Kennedy Fengling Li Elena Dobrovetsky Aiping Dong David Smil Sun‐Joon Min Melissa Landon Jennifer Lin‐Jones Xi‐Ping Huang Bryan L. Roth Matthieu Schapira Peter Atadja Dalia Barsyte‐Lovejoy Cheryl H. Arrowsmith Peter J. Brown Kehao Zhao Jian Jin Masoud Vedadi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(17):5255-5259
PRMT3 catalyzes the asymmetric dimethylation of arginine residues of various proteins. It is essential for maturation of ribosomes, may have a role in lipogenesis, and is implicated in several diseases. A potent, selective, and cell‐active PRMT3 inhibitor would be a valuable tool for further investigating PRMT3 biology. Here we report the discovery of the first PRMT3 chemical probe, SGC707, by structure‐based optimization of the allosteric PRMT3 inhibitors we reported previously, and thorough characterization of this probe in biochemical, biophysical, and cellular assays. SGC707 is a potent PRMT3 inhibitor (IC50=31±2 nM , KD=53±2 nM ) with outstanding selectivity (selective against 31 other methyltransferases and more than 250 non‐epigenetic targets). The mechanism of action studies and crystal structure of the PRMT3‐SGC707 complex confirm the allosteric inhibition mode. Importantly, SGC707 engages PRMT3 and potently inhibits its methyltransferase activity in cells. It is also bioavailable and suitable for animal studies. This well‐characterized chemical probe is an excellent tool to further study the role of PRMT3 in health and disease. 相似文献
904.
Krystyna Jackowska Aleksander T. Bieguński Magdalena Tagowska 《Journal of Solid State Electrochemistry》2008,12(4):437-443
The article reviews the application of a hard template approach in the formation of conducting polymers nanostructures. The
method involves the synthesis of a polymer within the pores or channels of a template. The influence of synthesis conditions
on fundamental features of nanostructured polypyrrole, polyaniline, and their derivatives is discussed.
Dedicated to the 70th birthday of Professor Oleg Petrii. 相似文献
905.
Experimental data for the reduction of transition metal complex ions obtained recently at mercury and single-crystal gold
electrodes are reviewed. It is shown that the effective charge on the reactant is generally not the same as the nominal charge,
but that it may be found on a basis of an analysis of the kinetic data together with the appropriate double layer data. In
addition, the effective charge on the product is usually smaller than the nominal value. As a result, the analysis of the
double layer effect involves the construction of corrected Tafel plots, which differ significantly from those described in
the early work of Frumkin.
Dedicated to Professor Oleg A Petrii on the occasion of his 70th birthday and in honor of his significant contributions to
the field of electrochemistry. 相似文献
906.
Magdalena Wanat 《Linear algebra and its applications》2006,414(1):304-309
We generalize two results: Kraaijevanger’s 1991 characterization of diagonal stability via Hadamard products and the block matrix version of the closure of the positive definite matrices under Hadamard multiplication. We restate our generalizations in terms of Pα-matrices and α-scalar diagonally stable matrices. 相似文献
907.
Magdalena Zyder 《Journal of organometallic chemistry》2009,694(26):4196-4201
The two new seven-coordinate anionic complexes of molybdenum(II), binuclear [(μ-Cl)2{Mo(μ-Cl)(SnCl3)(CO)3}2]2− and mononuclear [MoCl3(GeCl3)(CO)3]2−, have been synthesized and characterized by single-crystal X-ray diffraction studies. The binuclear complex exhibits a unique mode of reactivity towards norbornene. In a strictly anhydrous atmosphere the binuclear complex effectively initiates the ring-opening metathesis polymerization reaction of norbornene, but in the presence of water norbornene is efficiently transformed to the binorbornyl ether (C7H11)2O. 相似文献
908.
Izabela Magdalena Zaleska Masaru Kitagawa Shinji Sugihara Isao Ikeda 《Journal of polymer science. Part A, Polymer chemistry》2009,47(19):5169-5179
Applications of metal‐free living cationic polymerization of vinyl ethers using HCl · Et2O are reported. Product of poly(vinyl ether)s possessing functional end groups such as hydroxyethyl groups with predicted molecular weights was used as a macroinitiator in activated monomer cationic polymerization of ε‐caprolactone (CL) with HCl · Et2O as a ring‐opening polymerization. This combination method is a metal‐free polymerization using HCl · Et2O. The formation of poly(isobutyl vinyl ether)‐b‐poly(ε‐caprolactone) (PIBVE‐b‐PCL) and poly(tert‐butyl vinyl ether)‐b‐poly(ε‐caprolactone) (PTBVE‐b‐PCL) from two vinyl ethers and CL was successful. Therefore, we synthesized novel amphiphilic, biocompatible, and biodegradable block copolymers comprised polyvinyl alcohol and PCL, namely PVA‐b‐PCL by transformation of acid hydrolysis of tert‐butoxy moiety of PTBVE in PTBVE‐b‐PCL. The synthesized copolymers showed well‐defined structure and narrow molecular weight distribution. The structure of resulting block copolymers was confirmed by 1H NMR, size exclusion chromatography, and differential scanning calorimetry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5169–5179, 2009 相似文献
909.
Jaroslaw Chojnacki Magdalena Kloskowska Urszula Wjtowicz Wieslaw Wojnowski 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(8):m349-m351
In the title mononuclear lead silanethiolates, [Pb(C12H27O3SSi)2(C10H8N2)], (I), and [Pb(C12H27O3SSi)2(C24H16N2)]·0.5C6H6, (II), the Pb atom shows a distorted square‐pyramidal coordination with a PbON2S2 core in which one S atom lies in an axial position. Intermolecular π–π and C—H...π interactions stabilize the structures. The benzene solvent molecule in (II) lies on an inversion centre. 相似文献
910.