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21.
甘氨酸的应用及生产技术 总被引:24,自引:3,他引:24
论述了甘氨酸的性质、应用、合成工艺及结晶研究的进展 ,并对国内外甘氨酸的生产现状和应用前景进行了分析。 相似文献
22.
23.
Yoon-Jeong Park Jin Chang Pen-Chung Chen Victor Chi-Min Yang 《Biotechnology and Bioprocess Engineering》2001,6(5):326-331
With the aim of developing a pH-sensitive controlled drug release system, a poly (L-lysine) (PLL) based cationic semi-interpenetrating polymer network (semi-IPN) has been synthesized. This cationic hydrogel
was designed to swell at lower pH and de-swell at higher pH and therefore be applicable for achieving regulated drug release
at a specific pH range. In addition to the pH sensitivity, this hydrogel was anticipated to interact with an ionic drug, providing
another means to regulate the release rate of ionic drugs. This semi-IPN hydrogel was prepared using a free-radical polymerization
method and by crosslinking of the polyethylene glycol (PEG)-methacrylate polymer through the PLL network. The two polymers
were penetrated with each other via interpolymer complexation to yield the semi-IPN structures. The PLL hydrogel thus prepared
showed dynamic swelling/de-swelling behavior in response to pH change, and such a behavior was influenced by both the concentrations
of PLL and PEG-methacrylate. Drug release from this semi-IPN hydrogel was also investigated using a model protein drug, streptokinase.
Streptokinase release was found to be dependent on its ionic interaction with the PLL backbones as well as on the swelling
of the semi-IPN hydrogel. These results suggest that a PLL semi-IPN hydrogel could potentially be used as a drug delivery
platform to modulate drug release by pH-sensitivity and ionic interaction. 相似文献
24.
25.
Shuwan Zai Ruijie Han Wangen Zhao Chuang Ma Wenliang Huang Shengzhong Liu 《Liver Transplantation》2024,14(1):2303264
Defects within perovskite have been known to act as the nonradiative recombination centers, negatively impacting the carrier transport, which degrades the photovoltaic performance of perovskite solar cells (PSCs). Therefore, preparing a high-quality perovskite film is of vital significance. To this end, a room-temperature molten salt, dimethylamine formate (DMAFa), is introduced into perovskite precursor solution to regulate the crystallization process of CsPbI3 films. DMAFa can coordinate with Pb2+ as HCOO−-Pb2+ in the early stages, then HCOO−-Pb2+ is gradually displaced by I−-Pb2+ due to its decomposition during the subsequent annealing, thus delaying the crystallization rate, meanwhile, the DMA+ can interact with the uncoordinated Pb2+ to passivate defects of perovskite films, thereby, forming a high-quality CsPbI3 film with large grain size and low-defect density. As a result of this strategy, the power conversion efficiency is increased to 20.40%, and the open-circuit voltage is up to 1.21 V. These findings indicate that the introduction of DMAFa offers a fundamental way to achieve high-performance CsPbI3 PSCs. 相似文献
26.
Jin-Woo Lee Cheng Sun Jinho Lee Dong Jun Kim Won Jung Kang Seungbok Lee Donguk Kim Jinseok Park Tan Ngoc-Lan Phan Zhengping Tan Felix Sunjoo Kim Jung-Yong Lee Xichang Bao Taek-Soo Kim Yun-Hi Kim Bumjoon J. Kim 《Liver Transplantation》2024,14(8):2303872
High power conversion efficiency (PCE), long-term stability, and mechanical robustness are prerequisites for the commercial applications of organic solar cells (OSCs). In this study, a new star-shaped trimer acceptor (TYT-S) is developed and high-performance OSCs with a PCE of 19.0%, high photo-stability (t80% lifetime = 2600 h under 1-sun illumination), and mechanical robustness with a crack-onset strain (COS) of 21.6% are achieved. The isotropic molecular structure of TYT-S affords efficient multi-directional charge transport and high electron mobility. Furthermore, its amorphous structure prevents the formation of brittle crystal-to-crystal interfaces, significantly enhancing the mechanical properties of the OSC. As a result, the TYT-S-based OSCs demonstrate a significantly higher PCE (19.0%) and stretchability (COS = 21.6%) than the linear-shaped trimer acceptor (TYT-L)-based OSCs (PCE = 17.5% and COS = 6.4%) and the small-molecule acceptor (MYT)-based OSCs (PCE = 16.5% and COS = 1.3%). In addition, the increased molecular size of TYT-S, relative to that of MYT and dimer (DYT), suppresses the diffusion kinetics of the acceptor molecules, substantially improving the photostability of the OSCs. Finally, to effectively demonstrate the potential of TYT-S, intrinsically stretchable (IS)-OSCs are constructed. The TYT-S-based IS-OSCs exhibit high device stretchability (strain at PCE80% = 31%) and PCE of 14.4%. 相似文献
27.
Tomoyuki Suehiro Chie Kojima Sayako Tsumura Atsushi Harada Kenji Kono 《Biopolymers》2010,93(7):640-648
Collagen, which is used as a biomaterial, is the most abundant protein in mammals. We have previously reported that a dendrimer modified with collagen model peptides, (Gly‐Pro‐Pro)5, formed a collagen‐like triple‐helical structure, showing thermal reversibility. In this study, various collagen‐mimic dendrimers of different generations and at different binding ratios were synthesized, to investigate the relationship between the peptide clustering effect and the higher order structure formation. The formation of the higher order structure was influenced by the binding ratios of the peptide to the dendrimer, but was not influenced by the dendrimer generation. A spacer, placed between the dendrimer terminal group and the peptide, negatively contributed to the formation of the higher order structure. The collagen model peptides were also attached to poly(allylamine) (PAA) and poly‐L ‐lysine (poly(Lys)) to compare them with the collagen‐mimic dendrimers. The PAA‐based collagen‐mimic compound, bearing more collagen model peptides than the dendrimer, exhibited a thermally stable higher order structure. In contrast, this was not observed for the collagen‐mimic polymers based on poly(Lys). Therefore, dendrimers and vinyl polymers act as a scaffold for collagen model peptides and subsequently induce higher order structures. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 640–648, 2010. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com 相似文献
28.
Crystallization of the first three domains of the human insulin-like growth factor-1 receptor. 下载免费PDF全文
N. M. McKern M. Lou M. J. Frenkel A. Verkuylen J. D. Bentley G. O. Lovrecz N. Ivancic T. C. Elleman T. P. Garrett L. J. Cosgrove C. W. Ward 《Protein science : a publication of the Protein Society》1997,6(12):2663-2666
The insulin-like growth factor-1 receptor (IGF-1R) is a tyrosine kinase receptor of central importance in cell proliferation. A fragment (residues 1-462) comprising the L1-cysteine rich-L2 domains of the human IGF-1R ectodomain has been overexpressed in glycosylation-deficient Lec8 cells and has been affinity-purified via a c-myc tag followed by gel filtration. The fragment was recognized by two anti-IGF-1R monoclonal antibodies, 24-31 and 24-60, but showed no detectable binding of IGF-1 or IGF-2. Isocratic elution of IGF-1R/462 on anion-exchange chromatography reduced sample heterogeneity, permitting the production of crystals that diffracted to 2.6 A resolution with cell dimensions a = 77.0 A, b = 99.5 A, c = 120.1 A, and space group P2(1)2(1)2(1). 相似文献
29.
Aim
Characterization of polyhydroxyalkanoates (PHA) accumulated by halophilic bacteria isolated from solar salterns.Methods and Results
Twenty‐six halophilic isolates were obtained from solar salterns of Goa, India. They were screened for accumulation of PHA by Sudan black B, Nile blue A and Nile red stains. Strains H15, H16 and H26 were selected based on their intensity of Nile blue A/Nile red fluorescence. On the basis of phenotypic and genotypic characterization, the three isolates were identified as Bacillus megaterium. Growth kinetics and polymer accumulating capacity of strain H16 were studied in E2 mineral media with 2% glucose with/without NaCl. In the absence of NaCl, strain H16 accumulated PHA to 40·0% (w/w) of cell dry weight (CDW) at 42 h of growth, whereas in presence of 5% w/v NaCl, the culture showed longer lag phase of up to 24 h and accumulated a maximum PHA of 39% (w/w) CDW at 54 h of growth. The infrared spectra of both the polymers exhibited peaks at 1733·9 cm?1 characteristic of C=O. Scans of 1H nuclear magnetic resonance (NMR) showed a doublet at 2·5 ppm corresponding to methylene group (‐CH2), the signal at 5·3 ppm corresponded to methine group (‐CH‐), and another signal at 1·3 ppm corresponded to the methyl group (‐CH3). Scans of 13C NMR showed prominent peaks at 20, 40, 67–68 and 170 ppm, indicating the polymer to be homopolymer of 3‐hydroxybutyrates. The polymer is stable up to a temperature of 160°C.Conclusion
Three moderately halophilic isolates (strain H15, H16 and H26) capable of accumulating PHA were isolated from solar salterns of Ribandar Goa, India, and identified as B. megaterium based on phenotypic and genotypic characterization. Strain H16 accumulated polyhydroxybutyrate in the presence and absence of NaCl up to 40% of its CDW.Significance and Impact of the Study
This strain would be better suited for production of PHA at industrial level due to its tolerance to high concentration of NaCl. 相似文献30.
Guiding the Selection of Processing Additives for Increasing the Efficiency of Bulk Heterojunction Polymeric Solar Cells 下载免费PDF全文
Uyxing Vongsaysy Bertrand Pavageau Guillaume Wantz Dario M. Bassani Laurent Servant Hany Aziz 《Liver Transplantation》2014,4(3)
In bulk heterojunction (BHJ) polymeric organic solar cells (OSCs), the use of processing additives in the material formulation has emerged as a promising, cost‐effective, and widely applicable method for optimizing the phase separation between the donor (D) and acceptor (A) materials, thus increasing their efficiency. So far, however, there has been no systematic approach for identifying suitable processing additives for a given D:A system. A method based on the Hansen solubility parameters (HSPs) is proposed for guiding the selection of processing additives for a given D:A combination. The method is applied to the archetypical poly(3‐hexylthiophene) (P3HT) and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) system. The HSPs of these materials are determined and used to define a set of numerical criteria that need to be satisfied by a processing additive in order for it to be effective in realizing a higher efficiency OSC. Applying the selection criteria results in the identification of three novel processing additives. OSCs made of these formulations demonstrate an increase in their short‐circuit current density (JSC) and power conversion efficiency (PCE). These results demonstrate the efficiency of these novel processing additives and show that the HSPs represent a useful tool to determine and explore new types of processing additives for BHJ‐OSCs. 相似文献