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Ohne Zusammenfassung 相似文献
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Eliton S. Medeiros Luiz H. C. Mattoso Rubens Bernardes-Filho Delilah F. Wood William J. Orts 《Colloid and polymer science》2008,286(11):1265-1272
Nanostructured films of poly(o-ethoxyaniline) (POEA) alternated with cellulose nanofibrils (CnF) were successfully produced
by self assembly (SA) at different pH values and investigated by atomic force microscopy and ultraviolet-visible spectroscopy.
Results show that it was possible to build up films by alternating POEA and CnF layers with relatively precise architectural
control by controlling the number of layers and pH. Film thickness had a dependence on pH which is a combination of the effects
of the deposited amount for each POEA layer and the pH at which the absorption of the cellulose nanofibrils was carried out.
Comparison of alternated layers of POEA and CnF with multi-immersions of POEA at different pH values, as measured by the ratio
between slopes of the straight lines of deposited amount of polymer versus the number of self-assembled layers, shows that
alternate deposition at pH 2 has a fourfold increase in the slope. Alternatively, at pH 5, there is no significant difference
whether the deposition is alternated (POEA–CnF) or not (POEA). 相似文献
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Inglesby MK Gray GM Wood DF Gregorski KS Robertson RG Sabellano GP 《Colloids and surfaces. B, Biointerfaces》2005,43(2):83-94
Surface characteristics of untreated and solvent extracted rice straw and intact rice plant stem and sheath tissue have been investigated using reflectance Fourier transform infrared spectroscopy (FTIR-ATR), electrokinetic analysis (EKA), and scanning electron microscopy (SEM). Klason lignin and Kappa numbers were determined according to TAPPI standard methods. Sohxlet extractions were performed with hexanes, ethyl acetate, chloroform, ethanol-toluene and benzene-ethanol azeotropes. The FTIR reflectance spectra showed differences between the untreated sheath and stem tissues. It was found that the functional groups of the stem interior tissues were masked by another substance, which is proposed to be potassium oxalate monohydrate. This mineral salt, readily removed by water-washing, was affected by the solvent extractions with varying results. The extracted amounts ranged from 1 to 7%. While lipid removal was detectable by the FTIR reflectance method, the streaming potential method showed only slight differences between the curves representing the zeta potential (mV) as a function of pH of the untreated versus extracted samples. Reduced values of the iso-electric points were observed for the extracted samples as compared to the untreated rice straw, indicative of more acidic surface characteristics. 相似文献
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Jewel Hossain Ramalingam Natarajan Ashish K. Banerjee Swapan Majumdar 《Tetrahedron》2017,73(22):3139-3146
Various symmetrical and unsymmetrical isoxazoline embodied chiral macroheterocycles were synthesized from carbohydrate derived oximes. Our result shows that the mode of cycloaddition is dependent on the length and tether present in alkenyl chain of sugar moiety. Thus in some cases inter- and intramolecular cycloaddition of nitrile oxide were observed with high selectivity. The cycloadducts contains two sugar units linked via macrocycles thus they are considered as pseudo-disacharides. The stereochemistry of the newly formed chiral centers was established by 2D-NMR techniques and X-ray crystallographic studies. 相似文献
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Gomes JA Gossage JL Balu H Kesmez M Bowen F Lumpkin RS Cocke DL 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(13-14):3082-3086
The theoretically predicted water-oxygen van der Waals adduct has been experimentally confirmed by vibrational characterization using matrix isolation spectroscopic studies at 10 K. Vibrational bands for asymmetric and symmetric OH-stretching for this adduct have been found at 3728 cm(-1) and 3639 cm(-1), respectively. Theoretical calculations performed with Gaussian 98 software at the MP2/6-311++G(2d,2p) level of theory support the alternative structure of the hydrated complex proposed by this study. 相似文献
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Controlled release of 2‐heptanone using starch gel and polycaprolactone matrices and polymeric films
Gregory M. Glenn Artur P. Klamczynski Justin Shey Bor‐Sen Chiou Kevin M. Holtman Delilah F. Wood Charles Ludvik Gloria DeGrandi Hoffman William J. Orts Syed Imam 《先进技术聚合物》2007,18(8):636-642
Varroa jacobsoni is a parasitic mite that is threatening the honeybee industry in many parts of the world. 2‐Heptanone, a natural product made by honeybees at low concentrations, is effective at elevated concentrations in controlling mite populations in honeybee colonies, especially when released over a 42 day period. An extrusion process was used to encapsulate 14, 18, and 25% 2‐heptanone in a polycaprolactone (PCL) matrix. Less than 18% of the 2‐heptanone was encapsulated in the PCL matrix. The high vapor permeability of PCL to 2‐heptanone resulted in a high flux rate and limited the usefulness of PCL as an encapsulation matrix for controlled‐release devices. A starch gel containing three times its weight in 2‐heptanone was prepared from starch‐based microcellular foam (MCF). The gel had compressive, tensile, and flexural strength values in the range of 0.56 to 1.9 MPa. 2‐Heptanone quickly evaporated from non‐laminated gels. However, when the gel was laminated with different polymeric films, a wide range of flux rates was obtained. The T50 for gels laminated or coated with poly(vinyl alcohol) (PVAL, 99% hydrolyzed) and ethylene‐vinyl alcohol copolymer (EVAL) was 72 and 1030 days, respectively. The most promising film was a starch/glycerol film that released 50% of the 2‐heptanone (T50) in approximately 13 days. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Paulo H. S. Picciani Bluma G. Soares Eliton S. Medeiros Fernando G. de Souza Delilah F. Wood William J. Orts Luiz H. C. Mattoso 《Macromolecular theory and simulations》2009,18(9):528-536
Fibers of poly(lactic acid) (PLA) blended with p‐toluenesulfonic acid‐doped polyaniline, PAni.TSA, were obtained by electrospinning, following a factorial design which was used mainly to study the effect of four process parameters (PLA solution concentration, PAni solution concentration, applied voltage, and flow rate) on fiber diameter. Due to the non‐Gaussian spread of the fiber diameters, probability density functions (PDF's) were used to describe them, and the main effect analysis was performed considering the most representative values of these PDF's. This study suggests that the main factor which governs the fiber dimension is the concentration of the PAni solution and its synergy with the others factors. Furthermore, in spite of the high complexity of the electrospinning process, the statistical model was able to describe the process with 95% confidence, therefore enabling one to precisely predict fiber diameter. Nanofiber formation was simulated using the results of the experimental design and validation tests were performed to minimize the fiber diameter.
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Dr. Soumya Jyoti Singha Roy Conor Loynd Delilah Jewel Sarah E. Canarelli Elise D. Ficaretta Quan A. Pham Prof. Dr. Eranthie Weerapana Prof. Dr. Abhishek Chatterjee 《Angewandte Chemie (International ed. in English)》2023,62(27):e202300961
We have developed a novel visible-light-catalyzed bioconjugation reaction, PhotoCLIC, that enables chemoselective attachment of diverse aromatic amine reagents onto a site-specifically installed 5-hydroxytryptophan residue (5HTP) on full-length proteins of varied complexity. The reaction uses catalytic amounts of methylene blue and blue/red light-emitting diodes (455/650 nm) for rapid site-specific protein bioconjugation. Characterization of the PhotoCLIC product reveals a unique structure formed likely through a singlet oxygen-dependent modification of 5HTP. PhotoCLIC has a wide substrate scope and its compatibility with strain-promoted azide-alkyne click reaction, enables site-specific dual-labeling of a target protein. 相似文献
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Arianna O. Osgood Yunan Zheng Dr. Soumya Jyoti Singha Roy Dr. Nikolaos Biris Myer Hussain Conor Loynd Delilah Jewel Dr. James S. Italia Prof. Abhishek Chatterjee 《Angewandte Chemie (International ed. in English)》2023,62(19):e202219269
Site-specific incorporation of multiple distinct noncanonical amino acids (ncAAs) into proteins in mammalian cells is a promising technology, where each ncAA must be assigned to a different orthogonal aminoacyl-tRNA synthetase (aaRS)/tRNA pair that reads a distinct nonsense codon. Available pairs suppress TGA or TAA codons at a considerably lower efficiency than TAG, limiting the scope of this technology. Here we show that the E. coli tryptophanyl (EcTrp) pair is an excellent TGA-suppressor in mammalian cells, which can be combined with the three other established pairs to develop three new routes for dual-ncAA incorporation. Using these platforms, we site-specifically incorporated two different bioconjugation handles into an antibody with excellent efficiency, and subsequently labeled it with two distinct cytotoxic payloads. Additionally, we combined the EcTrp pair with other pairs to site-specifically incorporate three distinct ncAAs into a reporter protein in mammalian cells. 相似文献
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