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121.
Meifang Zhu Yang Liu Bin Sun Wei Zhang Xiaoli Liu Hao Yu Yu Zhang Dirk Kuckling Hans‐Juergen P. Adler 《Macromolecular rapid communications》2006,27(13):1023-1028
Summary: A series of high clay content Laponite XLS/polyacrylamide (PAAm) nanocomposite hydrogels (S‐M gels) with excellent resilience, low elastic hysteresis, and ultrahigh elongation, have been successfully synthesized. Based on our results, it is concluded that the mechanical properties of nanocomposite hydrogels probably depend to a great extent on the hydrophilicity and flexibility of the macromolecules. Moreover, it is found that the transparency during the in‐situ polymerization of S‐M gels does not change, which is quite different from clay/poly(N‐isopropylacrylamide) nanocomposite hydrogels.
122.
Leonid Unverfehrt Markus Stroebele Jochen Glaser Thorsten Langer Rolf‐Dieter Hoffmann Rainer Poettgen H.‐Juergen Meyer 《ChemInform》2011,42(36):no-no
The title compound is prepared by solid state reaction of EuF3, EuF2+x, and Li2(CN2) at 700 °C and characterized by single crystal XRD, 151Eu Moessbauer spectroscopy, and magnetic measurements. 相似文献
123.
通过电聚合沉积在基底上的聚吡咯膜容易剥离的问题可以通过粘合增强剂解决。我们设计并合成一类新化合物w-3-吡咯烷基磷酸将聚吡咯膜 通过化学键键合到金属基底上。本文描述了合成含有表面反应功能团的3-取代吡咯的过程。1-苯磺酰吡咯作为起始物经付-克反应得到3-取代吡咯。两种方法可以合成w-3-吡咯烷基磷酸酯。一种路线是:先磷酸化然后脱保护基最后还原羰基。这种方法适用于含有六个碳及以上的取代基。另一种路线是:先还原羰基然后磷酸化及脱保护。这种方法适用于短链及长链取代基。最后水解得到w-3-吡咯烷基磷酸。 相似文献
124.
The interest in understanding fundamental mechanisms underlying chromatography drastically increased over the past decades resulting in a whole variety of mostly semi-empirical models describing protein retention. Experimental data about the molecular adsorption mechanisms of lysozyme on different chromatographic ion-exchange materials were used to develop a mechanistical model for the adsorption of lysozyme onto a SP Sepharose FF surface based on molecular dynamic simulations (temperature controlled NVT simulations) with the Amber software package using a force-field based approach with a continuum solvent model. The ligand spacing of the adsorbent surface was varied between 10 and 20 Å. With a 10 Å spacing it was possible to predict the elution order of lysozyme at different pH and to confirm in silico the pH-dependent orientation of lysozyme towards the surface that was reported earlier. The energies of adsorption at different pH values were correlated with isocratic and linear gradient elution experiments and this correlation was used to predict the retention volume of ribonuclease A in the same experimental setup only based on its 3D structure properties. The study presents a strong indication for the validity of the assumption, that the ligand density of the surface is one of the key parameters with regard to the selectivity of the adsorbent, suggesting that a high ligand density leads to a specific interaction with certain binding sites on the protein surface, while at low ligand densities the net charge of the protein is more important than the actual charge distribution. 相似文献
125.
Michael Termer Christophe Carola Andrew Salazar Cornelia M. Keck Juergen Hemberger Joerg von Hagen 《Molecules (Basel, Switzerland)》2021,26(23)
Inflammation is the body’s response to infection or tissue injury in order to restore and maintain homeostasis. Prostaglandin E2 (PGE-2) derived from arachidonic acid (AA), via up-regulation of cyclooxygenase-2 (COX-2), is a key mediator of inflammation and can also be induced by several other factors including stress, chromosomal aberration, or environmental factors. Targeting prostaglandin production by inhibiting COX-2 is hence relevant for the successful resolution of inflammation. Waltheria indica L. is a traditional medicinal plant whose extracts have demonstrated COX-2 inhibitory properties. However, the compounds responsible for the activity remained unknown. For the preparation of extracts with effective anti-inflammatory properties, characterization of these substances is vital. In this work, we aimed to address this issue by characterizing the substances responsible for the COX-2 inhibitory activity in the extracts and generating prediction models to quantify the COX-2 inhibitory activity without biological testing. For this purpose, an extract was separated into fractions by means of centrifugal partition chromatography (CPC). The inhibitory potential of the fractions and extracts against the COX-2 enzyme was determined using a fluorometric COX-2 inhibition assay. The characterizations of compounds in the fractions with the highest COX-2 inhibitory activity were conducted by high resolution mass spectrometry (HPLC-MS/MS). It was found that these fractions contain alpha-linolenic acid, linoleic acid and oleic acid, identified and reported for the first time in Waltheria indica leaf extracts. After analyzing their contents in different Waltheria indica extracts, it could be demonstrated that these fatty acids are responsible for up to 41% of the COX-2 inhibition observed with Waltheria indica extract. Additional quantification of secondary metabolites in the extract fractions revealed that substances from the group of steroidal saponins and triterpenoid saponins also contribute to the COX-2 inhibitory activity. Based on the content of compounds contributing to COX-2 inhibition, two mathematical models were successfully developed, both of which had a root mean square error (RMSE) = 1.6% COX-2 inhibitory activity, demonstrating a high correspondence between predicted versus observed values. The results of the predictive models further suggested that the compounds contribute to COX-2 inhibition in the order linoleic acid > alpha linolenic acid > steroidal saponins > triterpenoid saponins. The characterization of substances contributing to COX-2 inhibition in this study enables a more targeted development of extraction processes to obtain Waltheria indica extracts with superior anti-inflammatory properties. 相似文献
126.
127.
Simon Grabowsky Peter Luger Juergen Buschmann Thomas Schneider Tanja Schirmeister Alexandre N. Sobolev Dylan Jayatilaka 《ChemInform》2012,43(42):no-no
Information on the S—O bond‐order in crystalline SO2 is derived from wavefunction refinement of high‐resolution low‐temperature XRD data. 相似文献
128.
Andreas Mautner Xiaohua Qin Barbara Kapeller Guenter Russmueller Thomas Koch Juergen Stampfl Robert Liska 《Macromolecular rapid communications》2012,33(23):2046-2052
Vinyl carbonates have recently been identified as a suitable alternative to (meth)acrylates, especially due to the low irritancy and cytotoxicity of these monomers. The drawback of some vinyl carbonates containing abstractable hydrogens arises through their moderate reactivity compared with acrylates. Within this paper, we use the thiol‐ene concept to enhance the photoreactivity of vinyl carbonates to a large extent to reach the level of those of similar acrylates. Mechanical properties of the final thiol‐ene polymers were determined by nanoindentation. Furthermore, low toxicity of all components was confirmed by osteoblast cell culture experiments. 相似文献
129.
Homogeneous Fenton reaction (H2O2/Fe2+ system) using significantly substoichiometric concentrations of H2O2 oxidant to oxidize phenol was characterized focusing on the formation of stable aromatic intermediates. Beyond the most abundant benzenediols, the pattern of aromatic intermediates was chiefly characterized by hydroxylated biphenyls and diphenyl ethers with different degrees of hydroxylation. Hydroxylated dibenzofurans (DBF), p,p′-dioxins, as well as highly condensed aromatic intermediates including polyols of polycyclic aromatic hydrocarbons (PAHs), could also be detected, but in lower concentrations. The formation of aromatic intermediates could be predicted on the basis of oxidative coupling reactions of resonance-stabilized radicals generated by the attack of the highly reactive hydroxyl radicals (OH*) on phenol. GC/MS identification of oxidative coupling intermediates was performed after derivatization of the solvent extracts. Derivatization reactions included silylation to give TMS (trimethylsilyl) ethers, as well as single-step extractive acetylation using acetic anhydride in alkaline aqueous solutions (pH 10.5) to give acetates. Solvent extraction of aqueous solutions, a prerequisite to generate TMS ethers, caused strong discrimination of polyols due to their low distribution coefficients in non-polar solvents. This discrimination could be overcome by extracting the in-situ formed acetates of the intermediates. Extractive acetylation allowed the detection of tri-, tetra-, and penta-hydroxylated aromatic intermediates generated by Fenton oxidation processes, which have been overlooked upto now. Thus, extractive acetylation to detect stable aromatic intermediates covering a wide range of hydroxylation degrees can foster the understanding, monitoring, and management of advanced oxidation processes, especially in the field of wastewater treatment. 相似文献
130.
The empirical one-parameter formula proposed by Alijah and Hinze (Philos Trans R Soc Lond A 364:2877, 2006) to estimate the off-diagonal adiabatic energy corrections has been tested systematically on the diatomic molecules for which exact data are known. It was found that the simple formula reproduces at least 90% of the energy shift. The parameter of the model, called c, is dimensionless and approximately independent of the molecule. Thus, the method can be applied to arbitrary molecules, diatomic or polyatomic, using the recommended value c = 0.11 of the parameter. 相似文献