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891.
The lower critical solution temperature (LCST) of cyclotriphosphazenes and polyphosphazenes grafted with a hydrophilic poly(ethylene glycol) (PEG) and a hydrophobic amino acid ester (AAE) as side groups could be quantitatively correlated with the overall hydrophobicity given by linear combination of the logarithmic partition coefficients of the corresponding free PEG and AAE measured in the 1-octanol/water system. Thus the LCSTs of phosphazenes were found to be well described as a linear function of a new parameter Pt defined as linear combination of the logarithmic partition coefficients of the free side groups, Kpeg and Kaae: where x is the mole fraction of PEG. The LCST of cyclotriphosphazenes has shown to be more sensitive to change in hydrophobicity than polyphosphazenes, indicating that the nature of the molecular structure plays an important role in determining their LCST. The additivity of the logarithms of the two partition coefficients for the parameter may indicate that the contribution of each constituent is independent, providing a facile method for prediction of the LCST of thermosensitive polymers. 相似文献
892.
Substrate Hunting for the Myxobacterial CYP260A1 Revealed New 1α‐Hydroxylated Products from C‐19 Steroids
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Dr. Michael Lisurek Prof. Dr. Jens Peter von Kries Dr. Josef Zapp Prof. Dr. Rita Bernhardt 《Chembiochem : a European journal of chemical biology》2016,17(1):90-101
Cytochromes P450 catalyze a variety of synthetically useful reactions. However, it is difficult to determine their physiological or artificial functions when a plethora of orphan P450 systems are present in a genome. CYP260A1 from Sorangium cellulosum So ce56 is a new member among the 21 available P450s in the strain. To identify putative substrates for CYP260A1 we used high‐throughput screening of a compound library (ca. 17 000 ligands). Structural analogues of the type I hits were searched for biotechnologically relevant compounds, and this led us to select C‐19 steroids as potential substrates. We identified efficient surrogate redox partners for CYP260A1, and an Escherichia coli‐based whole‐cell biocatalyst system was developed to convert testosterone, androstenedione, and their derivatives methyltestosterone and 11‐oxoandrostenedione. A detailed 1H and 13C NMR characterization of the product(s) from C‐19 steroids revealed that CYP260A1 is the very first 1α‐steroid hydroxylase. 相似文献
893.
Jesuí Vergílio Visentainer Maximiliano D’Addio Noffs Patricia de Oliveira Carvalho Vanessa Vivian de Almeida Cláudio Celestino de Oliveira Nilson Evelázio de Souza 《Journal of the American Oil Chemists' Society》2007,84(6):543-547
Lipid content and fatty acid composition were determined in edible meat of fifteen marine fish species caught on the Southeast
Brazilian coast and two from East Antarctic. Most of the fish had lipid amounts lower than 10% of their total weight. Palmitic
acid (C16:0) predominated, accounting for 54–63% of the total amount of saturated fatty acids. Oleic acid (C18:1n-9) was the
most abundant (49–69%) monounsaturated fatty acid, and docosahexaenoic acid (DHA) was the predominant polyunsaturated fatty
acid (PUFA), accounting for 31–84% of n-3 PUFA. n-3 PUFA level were highest in Antarctic fish meat, comprising 45% of the
total fatty acid content, which consisted of mainly EPA (16.1 ± 1.5 g/100 g lipids) and DHA (24.8 ± 2.4 g/100 g lipids). The
amounts of EPA + DHA in g/100 g of lipids on the Southeast Brazilian coast and Antarctic fish species investigated were found
to be similar: 42.0 ± 1.7 for Bonito cachorro, 41.0 ± 2.3 for Atum, and 39.4 ± 1.8 for peixe porco, respectively. All the
studied species exhibited an n-3/n-6 ratio higher than 3, which confirms the great importance of Southeast Brazilian coast
fish as a significant dietary source of n-3 PUFA. 相似文献
894.
B. Louis C. Detoni N.M.F. Carvalho C.D. Duarte O.A.C. Antunes 《Applied Catalysis A: General》2009,360(2):218-225
Mononuclear Cu(II) complexes have been synthesized, and their structure thoroughly characterized by electrospray ionization mass spectrometry (ESI-MS). These 2,2′-bipyridine and 1,10-phenantroline mononuclear Cu(II) complexes have been tested as catalysts in the partial oxidation of tetralin (1,2,3,4-tetrahydronaphthalene), using hydrogen peroxide as oxidant in acetonitrile/water as solvent.The complexes [Cu(bipy)3]Cl2·6H2O (1), [Cu(bipy)2Cl]Cl·5H2O (2), [Cu(bipy)Cl2] (3), [Cu(phen)3]Cl2·6H2O (4), [Cu(phen)2Cl]Cl·5H2O (5), [Cu(phen)Cl2] (6) were able to oxidize tetralin at room temperature, at high degrees of conversion (62.1% with 2) into α-tetralol and α-tetralon at 91% selectivity (81% in 1-tetralon).Depending on nature and number of ligands (bipyridine or phenantroline) surrounding Cu2+ cation, one was able to tailor both the activity toward tetralin oxidation, and the selectivity toward 1-tetralol and 1-tetralone products, but also to raise the yield in valuable α-tetralone. 相似文献
895.
Violeta Gulbiniene Greta Balciuniene Justina Petroniene Rita Viliene Irena Dumalakiene Ingrida Pilypiene Diana Ramasauskaite 《International journal of molecular sciences》2022,23(6)
Preterm premature rupture of membranes (PPROM) interrupts normal lung development, resulting in neonatal respiratory morbidity. Although post-PPROM risks have been researched, only a few studies have investigated noninvasively obtained amniotic fluid (AF) to predict neonatal outcomes. In this study, we aimed to determine whether epidermal growth factor (EGF) in vaginally-collected AF is a significant predictor of neonatal respiratory outcomes after PPROM. We analyzed EGF in vaginally-obtained AF from 145 women with PPROM at 22–34 weeks of gestation. The following neonatal outcomes were included: respiratory distress syndrome, surfactant need, duration and type of respiratory support, and bronchopulmonary dysplasia. We found that EGF concentration was associated with gestational age, and its medians were lower in neonates with respiratory morbidities than unaffected ones. EGF concentrations gradually declined, the lowest being in the most clinically ill patients. EGF < 35 pg/mL significantly predicted the odds of severe respiratory outcomes. EGF in noninvasively collected AF may be a reliable predictor for respiratory outcomes of preterm neonates with PPROM before 34 weeks of gestation. The results of our study may have implications for further research both in noninvasive amniotic fluid analysis and the management of patients after PPROM. 相似文献
896.
Rita Almeida Ribeiro 《Computer-Aided Civil and Infrastructure Engineering》1999,14(2):155-162
This article presents an application relevant to civil engineering that deals with the classification of the thermal quality of buildings using a fuzzy multiple‐attribute decision support tool. The aim of the article is to demonstrate the potential and flexibility of using these types of tools in the civil engineering arena. The application selected follows the Portuguese standards for classifying building insulation construction projects. 相似文献
897.
Daniela Nunes Rogério Colaço António Pereira Gonçalves Patrícia Almeida Carvalho 《Materials Characterization》2009,60(12):1607-1612
Magnetic domain configurations in YFe11Ti aggregates have been investigated by magnetic force microscopy. Single domain behaviour, stripe/maze domains, wavy domain structures and reverse spike domains have been observed. Domain wall energy of 6 mJ/m2 has been estimated based on the scale of the micromagnetic configurations. 相似文献
898.
Packet retransmission strategies are presented for 2x2 MIMO spatial multiplexing systems. Antennas for retransmission are selected to maximize an approximation of the throughput of the system. A sign change or conjugate operation is allowed for retransmitted packets. The proposed scheme performs selection of retransmission antennas based on the CSI at the receiver: only 1 bit of feedback is additionally required, along with the acknowledgement bits. When 2 packets are decoded with errors, retransmission follows a space time block code structure, allowing a seamless switching between spatial multiplexing and space time block coding. 相似文献
899.
Using the coherent optical frequency domain reflectometry technique, a non-invasive study has been made of the distributed gain in two pumping schemes for thulium-doped fibre amplifiers. The compared schemes employed 800+1050 nm or 800+1400 nm pump wavelengths, and it was concluded that the former is advantageous over the latter primarily due to the ground-state absorption and pumping mechanism. 相似文献
900.
In this paper we present results on the optimization of an pinpii‘n’ type a-Si:H based three color detector with voltage controlled spectral sensitivity. The sensor element was fabricated on a glass covered with Indium Tin Oxide (ITO) and consists of a p-i-n a-SiC:H multilayer structure which faces the incident illumination, followed by a-SiC:H(-p)/a-SiC:H(-i)/a-Si:H(-i′)/a-SiC:H(-n′)/ITO heterostructure, that allows the optically addressed readout.Results show that this approach leads to regionally different collection parameters resulting in multispectral photodiodes. In the polychromatic operation mode different sensitivity ranges are programmed by switching between different biases so that the basic colors can be resolved with a single device. Positive bias is needed under blue irradiation and moderated reverse bias under green. The threshold voltage between green and red sensitivity depends on the thickness of the bottom a-SiC:H (-i) layer, and corresponds to the complete confinement of the absorbed green photons across the pinpi sequence. As the thickness of the a-Si:H i'-layer increases, the self-reverse effect due to the front absorption will be balanced by the decrease of the self-forward effect due to the back absorption shifting the threshold voltage to lower reverse bias.The various design parameters are discussed and supported by a 2D numerical simulation. 相似文献