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991.
Dr. Thiruvancheril G. Gopakumar Dr. Matthias Bernien Holger Naggert Dr. Francesca Matino Christian F. Hermanns Dr. Alexander Bannwarth Svenja Mühlenberend Alex Krüger Dennis Krüger Fabian Nickel Waldemar Walter Prof. Dr. Richard Berndt Prof. Dr. Wolfgang Kuch Prof. Dr. Felix Tuczek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(46):15702-15709
Submono‐, mono‐ and multilayers of the Fe(II) spin‐crossover (SCO) complex [Fe(bpz)2(phen)] (bpz=dihydrobis(pyrazolyl)borate, phen=1,10‐phenanthroline) have beenprepared by vacuum deposition on Au(111) substrates and investigated with near edge X‐ray absorption fine structure (NEXAFS) spectroscopy and scanning tunneling microscopy (STM). As evidenced by NEXAFS, molecules of the second layer exhibit a thermal spin crossover transition, although with a more gradual characteristics than in the bulk. For mono‐ and submonolayers of [Fe(bpz)2(phen)] deposited on Au(111) substrates at room temperature both NEXAFS and STM indicate a dissociation of [Fe(bpz)2(phen)] on Au(111) into four‐coordinate complexes, [Fe(bpz)2], and phen molecules. Keeping the gold substrate at elevated temperatures ordered monolayers of intact molecules of [Fe(bpz)2(phen)] are formed which can be spin‐switched by electron‐induced excited spin‐state trapping (ELIESST). 相似文献
992.
Ligia Maria Moretto Francesca Montagner Renzo Ganzerla Paolo Ugo 《Analytical and bioanalytical chemistry》2013,405(11):3603-3610
Voltammetry of microparticles is applied to characterise and to identify solid analytes of interest in the field of cultural heritage. Nafion® is used for the immobilisation of solid microparticles onto the surface of a glassy carbon electrode by exploiting the deposition onto the electrode surface of a micro-volume of a suspension of the microsample in polymeric solution. Cyclic voltammetry and square wave voltammetry are applied to characterise and to identify the microparticles immobilised in the Nafion® coating. The analyte studied in this work is Prussian Blue as a typical inorganic pigment, with a relatively simple electrochemical behaviour. The proposed method is applied to a sample of Venetian marmorino plaster. The performance of Nafion® for this analysis is compared with that of the polymer Paraloid B72. Figure
From sampling the pigment in the work of art to recording the voltammetric signal with Nafion coated electrodes 相似文献
993.
Alan E. Enciso Francesca Lorandi Arshad Mehmood Marco Fantin Grzegorz Szczepaniak Benjamin G. Janesko Krzysztof Matyjaszewski 《Angewandte Chemie (International ed. in English)》2020,59(35):14910-14920
A facile and efficient two‐step synthesis of p‐substituted tris(2‐pyridylmethyl)amine (TPMA) ligands to form Cu complexes with the highest activity to date in atom transfer radical polymerization (ATRP) is presented. In the divergent synthesis, p‐Cl substituents in tris(4‐chloro‐2‐pyridylmethyl)amine (TPMA3Cl) were replaced in one step and high yield by electron‐donating cyclic amines (pyrrolidine (TPMAPYR), piperidine (TPMAPIP), and morpholine (TPMAMOR)) by nucleophilic aromatic substitution. The [CuII(TPMANR2)Br]+ complexes exhibited larger energy gaps between frontier molecular orbitals and >0.2 V more negative reduction potentials than [CuII(TPMA)Br]+, indicating >3 orders of magnitude higher ATRP activity. [CuI(TPMAPYR)]+ exhibited the highest reported activity for Br‐capped acrylate chain ends in DMF, and moderate activity toward C?F bonds at room temperature. ATRP of n‐butyl acrylate using only 10–25 part per million loadings of [CuII(TPMANR2)Br]+ exhibited excellent control. 相似文献
994.
Marina Piscopo Gian Carlo Tenore Rosaria Notariale Viviana Maresca Maria Maisto Francesca de Ruberto 《Natural product research》2020,34(18):2607-2611
AbstractIn this paper we report for the first time a method for the extraction of the protein fraction from Feijoa sellowiana Berg. fruit and its electrophoretic analysis. In addition we analyzed the protein fraction for its antioxidant activity and its effectiveness against different Gram-positive and Gram-negative bacteria both as American type culture collection (ATCC) standard and clinically isolated strains. Both antimicrobial and antioxidant activity resulted stronger respect to that previously obtained for the acetonic extract from the same fruit. Further, we study both activities also on the product of in vitro gastrointestinal digestion of F. sellowiana fruit proteins. The results showed that in vitro gastrointestinal digestion increased 10 fold the antioxidant activity, while the antimicrobial activity, tested only on ATCC strains, resulted from 2 to 4 fold increased. MTT assays showed the non-toxicity of these proteins both before and after digestion. 相似文献
995.
Francesca Rigano Marianna Oteri Giuseppe Micalizzi Domenica Mangraviti Paola Dugo Luigi Mondello 《Journal of separation science》2020,43(9-10):1773-1780
In a previous article, Rigano et al. established a new linear retention index system for the identification of triacylglycerols by liquid chromatography methods only on the basis of the retention behavior and independently from many experimental parameters. In that work, a database of 209 compounds was built, but only 54 of them, typical of vegetable oils, were confirmed by mass spectrometry. The aim of the present research is to extend the applicability of the novel approach to more complex samples, such as fish lipid extracts, and assess the complementarity between mass spectromtery and retention information to achieve univocal identification. With this purpose, a new software was implemented to make the identification process easy and automatic as in gas chromatography‐mass spectrometry where the retention index filter is added in the spectral search to discriminate between compounds with similar mass spectrometry spectra. A total of 69 species were identified and, thanks to their baseline separation obtained by an ultra high performance liquid chromatography method, a semiquantification was also performed. The species under investigation were Dicentrarchus labrax, coming from aquaculture and the wild. Some differences in their native lipid composition were observed, probably related to a different diet. A major number of samples would be necessary to confirm such a preliminary finding. 相似文献
996.
Dr. Martina Torelli Prof. Francesca Terenziani Dr. Alessandro Pedrini Dr. Francesca Guagnini Dr. Ilaria Domenichelli Prof. Chiara Massera Prof. Enrico Dalcanale 《ChemistryOpen》2020,9(2):261-268
The eligibility of tetraquinoxaline cavitands (QxCav) as molecular grippers relies on their unique conformational mobility between a closed (vase) and an open (kite) form, triggered in solution by conventional stimuli like pH, temperature and ion concentration. In the present paper, the mechanochemical conformational switching of ad hoc functionalized QxCav covalently embedded in an elastomeric polydimethylsiloxane and in a more rigid polyurethane matrix is investigated. The rigid polymer matrix is more effective in converting mechanical force into a conformational switch at the molecular level, provided that all four quinoxaline wings are covalently connected to the polymer. 相似文献
997.
Francesca Munari Carlo G. Barracchia Cinzia Franchin Francesca Parolini Stefano Capaldi Alessandro Romeo Luigi Bubacco Michael Assfalg Giorgio Arrigoni Mariapina D'Onofrio 《Angewandte Chemie (International ed. in English)》2020,59(16):6607-6611
In the brain of individuals with Alzheimer's disease, the regulatory protein ubiquitin is found conjugated to different lysine residues of tau protein assembled into pathological paired helical filaments. To shed light on the hitherto unexplored ubiquitination‐linked conformational transitions of tau, the availability of in vitro ubiquitin conjugation methods is of primary importance. In our work, we focused on the four‐repeat domain of tau and assembled an enzymatic machinery formed by UBE1, Ubc13, and CHIP enzymes. The enzymatic reaction resulted in monoubiquitination at multiple sites, reminiscent of the ubiquitination pattern observed in vivo. We further exploited chemoselective disulfide coupling reactions to construct three tau regioisomers with site‐specific monoubiquitination. Protein aggregation experiments revealed that the multiple enzyme‐derived products were unable to convert into amyloid fibrils, while the semisynthetic conjugates exhibited diverse capability to form filaments. This study contributes novel insight into the effects of a key post‐translational modification on aberrant protein self‐assembly. 相似文献
998.
Maria Pia Lenza Iker Oyenarte Dr. Tammo Diercks Jon Imanol Quintana Dr. Ana Gimeno Dr. Helena Coelho Ana Diniz Dr. Francesca Peccati Sandra Delgado Alexandre Bosch Dr. Mikel Valle Dr. Oscar Millet Prof. Dr. Nicola G. A. Abrescia Dr. Asís Palazón Dr. Filipa Marcelo Dr. Gonzalo Jiménez-Osés Prof. Dr. Jesús Jiménez-Barbero Dr. Ana Ardá Dr. June Ereño-Orbea 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):23971-23979
The glycan structures of the receptor binding domain of the SARS-CoV2 spike glycoprotein expressed in human HEK293F cells have been studied by using NMR. The different possible interacting epitopes have been deeply analysed and characterized, providing evidence of the presence of glycan structures not found in previous MS-based analyses. The interaction of the RBD 13C-labelled glycans with different human lectins, which are expressed in different organs and tissues that may be affected during the infection process, has also been evaluated by NMR. In particular, 15N-labelled galectins (galectins-3, -7 and -8 N-terminal), Siglecs (Siglec-8, Siglec-10), and C-type lectins (DC-SIGN, MGL) have been employed. Complementary experiments from the glycoprotein perspective or from the lectin's point of view have permitted to disentangle the specific interacting epitopes in each case. Based on these findings, 3D models of the interacting complexes have been proposed. 相似文献
999.
Novel carbon nanotube composites by grafting reaction with water-compatible redox initiator system 总被引:1,自引:0,他引:1
Giuseppe Cirillo Tommaso Caruso Silke Hampel Diana Haase Francesco Puoci Manfred Ritschel Albrecht Leonhardt Manuela Curcio Francesca Iemma Vyacheslav Khavrus Mandy Grobosch Nevio Picci 《Colloid and polymer science》2013,291(3):699-708
Multi-walled carbon nanotubes were chemically functionalized with methacrylic acid and methacrylated bovine serum albumin by free radical grafting reaction to obtain novel nanocomposites. The nanotubes were synthesized by aerosol-assisted chemical vapor deposition, and then the monomers were directly grafted by the action of hydrogen peroxide/ascorbic acid redox pair which allows operating in water-compatible and eco-friendly environment without the generation of any toxic reaction by-product. A multi-technique approach was used to evaluate the effectiveness of the grafting process employing Fourier transform infrared, Raman, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and thermogravimetric analyses. Considering the high importance of methacrylate polymers and bovine serum albumin, the proposed nanocomposites could be of great applicability in biomedical and pharmaceutical fields. 相似文献
1000.
In this paper a new class of nonstationary subdivision schemes is proposed to construct functions having all the main properties of B-splines, namely compact support, central symmetry and total positivity. We show that the constructed nonstationary subdivision schemes are asympotically equivalent to the stationary subdivision scheme associated with a B-spline of suitable degree, but the resulting limit function has smaller support than the B-spline although keeping its regularity. 相似文献