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81.
Xin-Hai Yu Doreen Itenyo Machanje Ben-Ke Xu Yong-Fen Xu 《Journal of Macromolecular Science: Physics》2013,52(3):489-503
A new diamine monomer 2,2-bis[4-(3-aminophenoxy)phenyl]propane (3-BAPOPP) was synthesized through two steps and its melting point was determined by differential scanning calorimetry (DSC). It was then copolymerized with 4,4′-oxydianiline (44ODA) and 4,4′-oxydiphthalic anhydride (ODPA) to obtain a series of aromatic polyimide(3-BAPOPP/44ODA/ODPA-PI) films. Fourier transform infrared (FT-IR) was used to characterize the structures of the monomer and the polyimide films. Water absorption, ultraviolet-visible (UV-Vis) spectroscopy, contact angle, DSC, and thermo-gravimetric analysis (TGA) were used to characterize the properties of 3-BAPOPP/44ODA/ODPA-P films. The results showed that the PI films had low water absorption in the range of 1.5%~1.9%, low surface energy in the range of 43.3 ~43.5 mJ/m2, glass transition temperature (Tg) in the range of 192.5°C~226.1°C, and dielectric constant in the range of 2.79~3.02 at 1 MHz. The films also exhibited good thermal properties and good optical properties, with the ultra violet cut-off wavelength being in the range of 346~364 nm. 相似文献
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Dr. Patrick Bitterwolf Dr. Ahmed E. Zoheir Julian Hertel Sandra Kröll Dr. Kersten S. Rabe Prof. Christof M. Niemeyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(66):e202202157
All-enzyme hydrogel (AEH) particles with a hydrodynamic diameter of up to 120 nm were produced intracellularly with an Escherichia coli-based in vivo system. The inCell-AEH nanoparticles were generated from polycistronic vectors enabling simultaneous expression of two interacting enzymes, the Lactobacillus brevis alcohol dehydrogenase (ADH) and the Bacillus subtilis glucose-1-dehydrogenase (GDH), fused with a SpyCatcher or SpyTag, respectively. Formation of inCell-AEH was analyzed by dynamic light scattering and atomic force microscopy. Using the stereoselective two-step reduction of a prochiral diketone substrate, we show that the inCell-AEH approach can be advantageously used in whole-cell flow biocatalysis, by which flow reactors could be operated for >4 days under constant substrate perfusion. More importantly, the inCell-AEH concept enables the recovery of efficient catalyst materials for stable flow bioreactors in a simple and economical one-step procedure from crude bacterial lysates. We believe that our method will contribute to further optimization of sustainable biocatalytic processes. 相似文献
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C. Sciascia J. Crochet T. Hertel G. Lanzani 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,75(2):115-120
We study the photo-induced transmission change (ΔT/T) upon
quasi-continuum laser excitation, for different modulation frequency and
excitation intensity in films of (6, 5) enriched CoMoCat single wall
nanotubes (SWNTs) embedded in a polymeric matrix. This technique probes
long-lived excited species, with lifetime in the 1 ms–1 s domain. The
observed line-shape of ΔT/T spectra that can be assigned to a
superposition of ground state bleaching and absorption modulation. We
speculate that photo-excitation creates charges which get trapped in the
sample, acquiring ms lifetime. This causes bleaching of the ground state
absorption due to state filling and possibly a tube diameter expansion, with
consequent blue shift of the optical transition. 相似文献
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[reaction: see text] We have synthesized a series of 2,4,5-trisubstituted tetrahydropyran derivatives to determine the utility of this scaffold as a peptidomimetic platform. The key synthetic steps involved a palladium-mediated cross-coupling reaction of a dihydropyran-4-one moiety to introduce R(2) followed by a sequential regio- and diastereoselective reduction of sp(2) carbon centers. Selected compounds have shown biological activity at melanocortin receptors, indicating that this scaffold may be useful in the design of peptidomimetics relating to a tripeptide structure. 相似文献
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