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排序方式: 共有191条查询结果,搜索用时 46 毫秒
91.
Alissandratos A Baudendistel N Hauer B Baldenius K Flitsch S Halling P 《Chemical communications (Cambridge, England)》2011,47(2):683-685
The enzyme catalysed esterification of starch and fatty acids with terminal triple bonds is described. This material can be used as an acceptor for azide containing molecules, through azide/alkyne cycloaddition. The potential is illustrated by the production of fluorescently-labelled starch, and a biotinylated derivative which can bind streptavidin. 相似文献
92.
93.
Ioannis Matiatos Apostolos Alexopoulos 《Isotopes in environmental and health studies》2013,49(4):512-529
The present study examines the isotopic and hydrochemical composition of 18 inland spring waters and 3 coastal karstic spring waters, covering the period between October 2005 and March 2008. The stable isotopes (18O, 2H) processing has revealed the absence of significant evaporation phenomena and that the origin of fresh water samples is meteoric. Using 18O values in rainfall waters, an average line of isotopic depletion with altitude has been constructed, extracting a rate of?0.45‰/100 m as typical for the study area. Furthermore, the mean altitude of recharge of the springs has been estimated by plotting the groundwater sampling points on a δ18O versus altitude diagram. Hydrochemistry results have shown that the dissolution of carbonate, flysch and ophiolitic formations defines the hydrochemical characteristics of groundwater. Moreover, seawater intrusion in the coastal area is significantly high, causing the water in the three karstic springs to be brackish. 相似文献
94.
Degradation of 4-hydroxybenzoic acid by combined ultrasound irradiation and catalytic wet peroxide oxidation 总被引:5,自引:0,他引:5
Nikolopoulos AN Igglessi-Markopoulou O Papayannakos N 《Ultrasonics sonochemistry》2004,11(3-4):183-186
The aim of this study is to explore the potential benefits from the combined use of ultrasound irradiation and catalytic wet peroxide oxidation for the degradation of 4-hydroxybenzoic acid (4-HBA). The target compound degradation was studied under direct and indirect sonication, while silent conditions were employed as reference. The catalyst, a mixed (Al-Fe) pillared clay named FAZA, was in the form of powder and of extrudates. In the case of extrudates it was observed that ultrasound improves the catalyst performance due to reduction of diffusion resistance, thereby increasing the conversion after 4 h by 12-15 times. Increasing the initial concentration of 4-HBA was found to lead to lower conversion. The combined ultrasonic/catalytic process appears very promising for environmental applications. 相似文献
95.
Dr. Daniel Fankhauser Dr. Apostolos Alissandratos Dr. Mantas Liutkus Prof. Christopher J. Easton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(69):17487-17494
Aliphatic γ-chloro-α-amino acids incorporated in place of their canonical analogues through cell-free protein synthesis act as heat-labile linkers, offering a useful strategy for the straightforward production of target peptides as fusion proteins, from which the targets are readily released. Until now, the natural abundance of aliphatic amino acids in peptides has limited the scope of the method, as it leads to undesired cleavage sites in synthesized products, but here the authors report the development of a new cleavable chloro amino acid that incorporates in place of the relatively rare amino acid methionine, thus greatly expanding the scope of producible targets. This new strategy is employed for simplified peptide synthesis with a methionine-free fusion partner, allowing single-site incorporation of the cleavable linker for clean release and easy purification of the target peptide. Its utility is demonstrated through the straightforward preparation of two peptides reported to be challenging targets and not accessible through standard solid-phase chemical methodologies, as well as analogues. 相似文献
96.
Synthesis via ATRP,kinetics study and characterization (molecular‐morphological) of 3‐Arm star diblock copolymers of the (PS‐b‐P2VP)3 type
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George Polymeropoulos Dimitrios Moschovas Anastasia Kati Apostolos Karanastasis Styliani Pelekanou Panagiotis Christakopoulos Georgios Sakellariou Apostolos Avgeropoulos 《Journal of polymer science. Part A, Polymer chemistry》2015,53(1):23-32
The synthesis of five homopolymers (PS)3 and the corresponding diblock copolymer 3‐arm stars of the (PS‐b‐P2VP)3 type is reported through atom transfer radical polymerization. Such star homo‐ and copolymers are prepared without any addition of solvent (bulk polymerization). The kinetics study results lead to the ability of predicting the best polymerization time with high values of monomer to polymer conversion, sufficient polydispersity indices and average molecular weights. Molecular characterization through size exclusion chromatography, viscometry, low‐angle laser light scattering, proton and carbon nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR, respectively) verified the successful synthesis of both homopolymer and copolymer 3‐arm star‐like architectures. Furthermore, the morphological characterization of the final copolymers is reported through transmission electron microscopy studies verifying the self‐assembly without any indication of homopolymer or Cu(I) traces. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 23–32 相似文献
97.
Nikolaos Chalmpes Dimitrios Moschovas Iosif Tantis Athanasios B. Bourlinos Aristides Bakandritsos Renia Fotiadou Michaela Patila Haralambos Stamatis Apostolos Avgeropoulos Michael A. Karakassides Dimitrios Gournis 《Molecules (Basel, Switzerland)》2021,26(6)
Hypergolic systems rely on organic fuel and a powerful oxidizer that spontaneously ignites upon contact without any external ignition source. Although their main utilization pertains to rocket fuels and propellants, it is only recently that hypergolics has been established from our group as a new general method for the synthesis of different morphologies of carbon nanostructures depending on the hypergolic pair (organic fuel-oxidizer). In search of new pairs, the hypergolic mixture described here contains polyaniline as the organic source of carbon and fuming nitric acid as strong oxidizer. Specifically, the two reagents react rapidly and spontaneously upon contact at ambient conditions to afford carbon nanosheets. Further liquid-phase exfoliation of the nanosheets in dimethylformamide results in dispersed single layers exhibiting strong Tyndall effect. The method can be extended to other conductive polymers, such as polythiophene and polypyrrole, leading to the formation of different type carbon nanostructures (e.g., photolumincent carbon dots). Apart from being a new synthesis pathway towards carbon nanomaterials and a new type of reaction for conductive polymers, the present hypergolic pairs also provide a novel set of rocket bipropellants based on conductive polymers. 相似文献
98.
Christina Miskaki Ioannis Moutsios Gkreti-Maria Manesi Konstantinos Artopoiadis Cheng-Yen Chang Egor A. Bersenev Dimitrios Moschovas Dimitri A. Ivanov Rong-Ming Ho Apostolos Avgeropoulos 《Molecules (Basel, Switzerland)》2020,25(23)
The synthesis of two (2) novel triblock terpolymers of the ABC type and one (1) of the BAC type, where A, B and C are chemically different segments, such as polystyrene (PS), poly(butadiene) (PB1,4) and poly(dimethylsiloxane) (PDMS), is reported; moreover, their corresponding molecular and bulk characterizations were performed. Very low dimensions are evident from the characterization in bulk from transmission electron microscopy studies, verified by small-angle X-ray data, since sub-16 nm domains are evident in all three cases. The self-assembly results justify the assumptions that the high Flory–Huggins parameter, χ, even in low molecular weights, leads to significantly well-ordered structures, despite the complexity of the systems studied. Furthermore, it is the first time that a structure/properties relationship was studied for such systems in bulk, potentially leading to prominent applications in nanotechnology and nanopatterning, for as low as sub-10 nm thin-film manipulations. 相似文献
99.
Apostolos Avgeropoulos Sofia Rangou Vahik Krikorian Edwin L. Thomas 《Macromolecular Symposia》2008,267(1):16-20
Synthesis of 2nd generation dendritic polymeric materials via anionic polymerization procedures in combination with chlorosilane chemistry, consisting either from one polydienic segment (homopolymers) or from two chemically different polydienic components (copolymers), is described. The polydienes used were poly(butadiene) (PB) with ∼90% 1,4-isomerism and poly(isoprene) (PI) with increased 3,4-isomerism (∼60%). Molecular characterization of intermediate products and the final dendritic materials was made with Gel Permeation Chromatography (GPC), Membrane and Vapour Pressure Osmometry (MO and VPO respectively), Gas Chromatography –Mass Spectroscopy (GC-MS) and 1H-Nuclear Magnetic Resonance (1H-NMR) Spectroscopy, leading to the conclusion that they can be considered model polymers. Morphological studies solely with Transmission Electron Microscopy (TEM) have been conducted on two of the four synthesized copolymer samples exhibiting microphase separation between the two polydiene segments. 相似文献
100.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献