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71.
Sulphur-headgroup organic molecules have been chemisorbed on Cu(1 0 0) as self-assembled monolayers (SAMs) in highly-ordered two-fold symmetry structures, and the electronic states induced at the interface have been measured by photoemission: a close similarity of the main interface states for methane-thiolate and mercaptobenzoxazole on Cu(1 0 0) in the same p(2 × 2)-phase is observed. The bonding states for methane-thiolate/Cu(1 0 0) in the p(2 × 2) and c(2 × 2) structures have been compared to ab-initio calculation of the total density of states (DOS) for the S/Cu(1 0 0) system in the same phases. The major role of the S-Cu bonding to determine the density of state evolution at the interface is brought to light. The observed differences in the two phases depend mainly on the charge distribution associated to the different molecular packing, with a minor role of the radical group. 相似文献
72.
Paolo Matteini Giovanni Agati Patrizia Pinelli Andrea Goti 《Monatshefte für Chemie / Chemical Monthly》2011,45(2):885-893
Abstract
The interaction of the model flavonoid glycoside rutin with the flavonoid reagent diphenylborinic acid 2-aminoethyl ester (DPBA) was investigated using a combination of HPLC–DAD–ESI–MS analysis, UV–visible spectroscopy, and semiempirical calculations. Mass spectra and spectroscopic data made it possible to describe the complexation pathway as addition of diphenylboron groups to the two available 3′,4′-o-diphenolic and the 5-hydroxy-4-keto coordinating sites of rutin. Semiempirical calculations were carried out to obtain the conformation of the most stable DPBA/rutin adducts. The results showed that a number of complexation dynamics can occur as a function of the characteristics of the medium (type and pH of the solvent) and of the amount of DPBA. This work suggests the possibility of substantially improving existing procedures for recognition of flavonoid compounds by choice of suitable experimental conditions. 相似文献73.
Patrizia Trovalusci Danilo Capecchi Giuseppe Ruta 《Archive of Applied Mechanics (Ingenieur Archiv)》2009,79(11):981-997
This paper presents an overview of the origin of multiscale approaches in mechanics. While the pioneer molecular models of
linear elastic bodies by Navier, Cauchy and Poisson were contradicted by experiments, the phenomenological energetic approach
by Green still seems suitable for simple materials only. Voigt’s molecular model, here reinterpreted in the light of contemporary
mechanics, reconciled the two approaches providing a conceptual guideline for developing constitutive models based on a direct
link between continuum and discrete solid mechanics. Such a theoretical background proves to be especially suitable for new
complex materials. An example referred to masonry-like materials is given. 相似文献
74.
75.
Romana Krištof Suzana Košenina Benjamin Zorko Jasmina Kožar Logar 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(2):675-679
The aim of the research was to obtain first results of tritium in the organic matter of environmental samples in the vicinity of Kr?ko NPP. The emphasis was on the layout of suitable sampling network of crops and fruits in nearby agricultural area. Method for determination of tritium in organic matter in the form of Tissue Free Water Tritium (TFWT) and Organically Bound Tritium (OBT) has been implemented. Capabilities of the methods were tested on real environmental samples and its findings were compared to modeled activities of tritium from atmospheric releases and literature based results of TFWT and OBT. 相似文献
76.
77.
Borghetti P Goldoni A Castellarin-Cudia C Casalis L Herberg F Floreano L Cossaro A Verdini A Gebauer R Ghosh P Sangaletti L 《Langmuir : the ACS journal of surfaces and colloids》2010,26(24):19007-19013
The role of potassium in the formation of synthetic eumelanin aggregates is investigated by atomic force microscopy and soft-X-ray spectroscopy. Control over the thin film granularity is achieved by using K salts, in both drop casting and electrodeposition of eumelanin thin films. Further control over orientation is made possible by a suitable choice of the substrate: evidence of self-assembly is found for thin films deposited on gold. Finally, it is shown that the potassium content affects not only the samples morphology, but also the low-lying states in the valence band, where a transfer of spectral weight across the HOMO-LUMO gap is observed, disclosing possible applications of this multifunctional biomacromolecule. 相似文献
78.
Ujević I Ninčević-Gladan Z Roje R Skejić S Arapov J Marasović I 《Molecules (Basel, Switzerland)》2010,15(10):6835-6849
This is the first study that presents concentrations of domoic acid detected in the whole shellfish tissue from breeding and harvesting areas along the Croatian coast of the Adriatic Sea during the period 2006 to 2008. Shellfish sample analyses after SAX cleaning procedures, using a UV-DAD-HPLC system, showed the presence of domoic acid in four species. The most prevalent of those species were the blue mussel (Mytilus galloprovincialis), followed by European flat oyster (Ostrea edulis), Mediterranean scallop (Pecten jacobaeus) and proteus scallop (Flexopecten proteus). Domoic acid, a potentially lethal phycotoxin that causes amnesic shellfish poisoning (ASP), was detected for the first time in January 2006 with the highest value of 6.5486 μg g?1 in whole shellfish tissue. Pseudo-nitzschia spp. bloom events preceded these high domoic acid concentrations. According to this study, retention of domoic acid in the blue mussel M. galloprovincialis is more than 42 days. This investigation indicates the first presence of domoic acid in Croatian shellfish, but in concentrations under the regulatory limit (20 μg g?1), therefore shellfish consumption was not found to endanger human health. 相似文献
79.
Francesca Tessore Dr. Elena Cariati Prof. Franco Cariati Prof. Dominique Roberto Prof. Renato Ugo Prof. Patrizia Mussini Prof. Cristiano Zuccaccia Dr. Alceo Macchioni Prof. 《Chemphyschem》2010,11(2):495-507
A series of 4‐X‐1‐methylpyridinium cationic nonlinear optical (NLO) chromophores (X=(E)‐CH?CHC6H5; (E)‐CH?CHC6H4‐4′‐C(CH3)3; (E)‐CH?CHC6H4‐4′‐N(CH3)2; (E)‐CH?CHC6H4‐4′‐N(C4H9)2; (E,E)‐(CH?CH)2C6H4‐4′‐N(CH3)2) with various organic (CF3SO3?, p‐CH3C6H4SO3?), inorganic (I?, ClO4?, SCN?, [Hg2I6]2?) and organometallic (cis‐[Ir(CO)2I2]?) counter anions are studied with the aim of investigating the role of ion pairing and of ionic dissociation or aggregation of ion pairs in controlling their second‐order NLO response in anhydrous chloroform solution. The combined use of electronic absorption spectra, conductimetric measurements and pulsed field gradient spin echo (PGSE) NMR experiments show that the second‐order NLO response, investigated by the electric‐field‐induced second harmonic generation (EFISH) technique, of the salts of the cationic NLO chromophores strongly depends upon the nature of the counter anion and concentration. The ion pairs are the major species at concentration around 10?3 M , and their dipole moments were determined. Generally, below 5×10?4 M , ion pairs start to dissociate into ions with parallel increase of the second‐order NLO response, due to the increased concentration of purely cationic NLO chromophores with improved NLO response. At concentration higher than 10?3 M , some multipolar aggregates, probably of H type, are formed, with parallel slight decrease of the second‐order NLO response. Ion pairing is dependent upon the nature of the counter anion and on the electronic structure of the cationic NLO chromophore. It is very strong for the thiocyanate anion in particular and, albeit to a lesser extent, for the sulfonated anions. The latter show increased tendency to self‐aggregate. 相似文献
80.
Amol Date Patrizia Pasini Sylvia Daunert 《Analytical and bioanalytical chemistry》2010,398(1):349-356
Bacterial whole-cell biosensing systems provide important information about the bioavailable amount of target analytes. They
are characterized by high sensitivity and specificity/selectivity along with rapid response times and amenability to miniaturization
as well as high-throughput analysis. Accordingly, they have been employed in various environmental and clinical applications.
The use of spore-based sensing systems offers the unique advantage of long-term preservation of the sensing cells by taking
advantage of the environmental resistance and ruggedness of bacterial spores. In this work, we have incorporated spore-based
whole-cell sensing systems into centrifugal compact disk (CD) microfluidic platforms in order to develop a portable sensing
system, which should enable the use of these hardy sensors for fast on-field analysis of compounds of interest. For that,
we have employed two spore-based sensing systems for the detection of arsenite and zinc, respectively, and evaluated their
analytical performance in the miniaturized microfluidic format. Furthermore, we have tested environmental and clinical samples
on the CD microfluidic platforms using the spore-based sensors. Germination of spores and quantitative response to the analyte
could be obtained in 2.5–3 h, depending on the sensing system, with detection limits of 1 × 10−7 M for arsenite and 1 × 10−6 M for zinc in both serum and fresh water samples. Incorporation of spore-based whole-cell biosensing systems on microfluidic
platforms enabled the rapid and sensitive detection of the analytes and is expected to facilitate the on-site use of such
sensing systems. 相似文献