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121.
Livraghi S Corazzari I Paganini MC Ceccone G Giamello E Fubini B Fenoglio I 《Chemical communications (Cambridge, England)》2010,46(44):8478-8480
A safe UV filter may be obtained by inhibiting the photo-generation of free radicals through modification of the surface of TiO(2) nanoparticles with carbon. 相似文献
122.
L. Elviri F. Speroni M. Careri A. Mangia L. Sanità di Toppi M. Zottini 《Journal of chromatography. A》2010,1217(25):4120-4126
Reversed-phase liquid chromatography (RPLC) and electrospray (ESI)-linear ion trap (LIT) mass spectrometry was applied to the direct characterization of in vivo S-nitrosylated (SNO) phytochelatins (PCs) expressed in cadmium-stressed Arabidopsis thaliana cells. Cys-nitrosylation is under discussion as in vivo redox-based post-translational modification of proteins and peptides in plants in which the –NO group is involved as signal molecule in different biological functions. The gas-phase ion chemistry of in vivo and in vitro generated SNO-PCs was compared with the aim of evaluating NO binding stability and improving MS knowledge about peptide nitrosation. Using RPLC separation and ESI-LIT-MS, mono-nitrosylated PCs were identified in in vivo cadmium treated A. thaliana cells without derivatization. The in vivo binding of the NO group to PC2, PC3 and PC4 resulted to occur selectively on only one cystein residue. The fragmentation pathway energies of the in vitro GSNO-generated NO-PCs with respect to the in vivo NO-PCs were investigated, suggesting the presence of a different internal stability for these molecules. By carrying out MS2 experiments on these quasi-symmetric peptides, the different stability degree of the NO group was demonstrated to be correlated with the PC chain length. In addition, the data obtained highlight a putative role of the adjacent Glu/Cys motif in the gas-phase stability of the NO-containing molecule. 相似文献
123.
El-Ghayoury A Mézière C Simonov S Zorina L Cobián M Canadell E Rovira C Náfrádi B Sipos B Forró L Batail P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(47):14051-14059
We report on the acid ethylenedithiotetrathiafulvaleneamidoglycine (EDT-TTF-CO-NH-CH(2)-CO(2)H; 1; EDT-TTF=ethylenedithiotetrathiafulvalene) and the 1:1 adduct [(EDT-TTF)(·+)-CO-NH-CH(2)-(CO(2))(-)][(EDT-TTF)-CO-NH-CH(2)-(CO(2)H)]·CH(3)OH (2), a new type of hydrogen-bonded, 1:1 acid/zwitterion hybrid embrace of redox peptidics into a two-dimensional architecture, an example of a system deliberately fashioned so that oxidation of π-conjugated cores toward the radical-cation form would interfere with the activity of the appended ionizable residues in the presence of a templating base during crystal growth. First-principles calculations demonstrate that, notwithstanding preconceived ideas, a metallic state is more stable than the hole-localized alternatives for a neat 1:1 neutral acid/zwitterion hybrid. The inhomogeneous Coulomb field associated with proton-shared, interstacks O-H···O hydrogen bonds between the ionizable residues distributed on both sides of the two-dimensional π-conjugated framework leads, however, to a weak hole localization responsible for the activated but high conductivity of 1 S cm(-1). This situation is reminiscent of the role of the environment on electron transfer in tetraheme cytochrome c, in which the protonation state of a heme propionate becomes paramount, or ion-gated transport phenomena in biology. These observations open rather intriguing opportunities for the construction of electronic systems at the interface of chemistry and biology. 相似文献
124.
Parracino A Gajula GP di Gennaro AK Neves-Petersen MT Rafaelsen J Petersen SB 《Journal of fluorescence》2011,21(2):663-672
Medical interest in nanotechnology originates from a belief that nanoscale therapeutic devices can be constructed and directed
towards its target inside the human body. Such nanodevices can be engineered by coupling superparamagnetic nanoparticle to
biomedically active proteins. We hereby report the immobilization of a PhEst, a S-formylglutathione hydrolase from the psychrophilic
P. haloplanktis TAC125 onto the gold coated surface of modified superparamagnetic core-shell nanoparticles (Fe3O4@Au). The synthesis of the nanoparticles is also reported. S-formylglutathione hydrolases constitute a family of ubiquitous
enzymes which play a key role in formaldehyde detoxification both in prokaryotes and eukaryotes. PhEst was originally annotated
as a putative feruloyl esterase, an enzyme that releases ferulic acid (an antioxidant reactive towards free radicals such
as reactive oxygen species) from polysaccharides esters. Dynamic light scattering, scanning electron microscopy with energy
dispersive X-ray spectroscopy, UV–visible absorption spectroscopy, fluorescence spectroscopy, magnetic separation technique
and enzyme catalytic assay confirmed the chemical composition of the gold covered superparamagnetic nanoparticles, the binding
and activity of the enzyme onto the nanoparticles. Activity data in U/ml confirmed that the immobilized enzyme is approximately
2 times more active than the free enzyme in solution. Such particles can be directed with external magnetic fields for bio-separation
and focused towards a medical target for therapeutical as well as bio-sensor applications. 相似文献
125.
Leo Liberti Nenad Mladenović Giacomo Nannicini 《Mathematical Programming Computation》2011,3(4):349-390
Finding good (or even just feasible) solutions for Mixed-Integer Nonlinear Programming problems independently of the specific
problem structure is a very hard but practically important task, especially when the objective and/or the constraints are
nonconvex. With this goal in mind, we present a general-purpose heuristic based on Variable Neighborhood Search, Local Branching,
a local Nonlinear Programming algorithm and Branch-and-Bound. We test the proposed approach on MINLPLib, comparing with several
existing heuristic and exact methods. An implementation of the proposed heuristic is freely available and can employ all NLP/MINLP
solvers with an AMPL interface as the main search tools. 相似文献
126.
We study quantum learning algorithms for quantum measurements. The optimal learning algorithm is derived for arbitrary von Neumann measurements in the case of training with one or two examples. The analysis of the case of three examples reveals that, differently from the learning of unitary gates, the optimal algorithm for learning of quantum measurements cannot be parallelized, and requires quantum memories for the storage of information. 相似文献
127.
Mohamed Saïdi 《Mathematische Zeitschrift》2014,277(1-2):361-372
We show the existence of group-theoretic sections of the “étale-by-geometrically abelian” quotient of the arithmetic fundamental group of hyperbolic curves over $p$ -adic local fields relative to a proper and flat model which are non-geometric, i.e., which do not arise from rational points. 相似文献
128.
In this paper, we characterize all the finite dimensional algebras that are derived equivalent to an m?cluster tilted algebra of type $\mathbb{A}$ . These algebras are gentle, and we show that the derived class of such an algebra is completely determined by the rank of its Grothendieck group and the dimension of its first Hochschild cohomology group. 相似文献
129.
130.