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991.
Philipp A. Mueller Giuseppe Storti Massimo Morbidelli Charalampos A. Mantelis Thierry Meyer 《Macromolecular Symposia》2007,259(1):218-225
Summary: Experiments of methyl methacrylate dispersion polymerization are carried out in a reaction calorimeter using PDMS-mMA as surfactant. Different stabilizer concentrations from 0 to 10 wt% with respect to monomer have been considered in order to control particle morphology. The analysis by scanning electron microscopy reveals a definite decrease of the total particle surface area at decreasing stabilizer concentration. At the same time, the analysis of the polymer microstructure by gel permeation chromatography shows a trend of the average molecular weight towards smaller values. In particular, a second mode at low molecular weights has been observed leading to bimodal molecular weight distributions. The experimental results are compared with simulation results obtained through a detailed kinetic model developed in previous studies. 1 The key role of the radical exchange between continuous and dispersed phases is confirmed. 相似文献
992.
Mariano Anderle Massimo Bersani Lia Vanzetti Simone Pederzoli 《Macromolecular Symposia》2006,238(1):11-15
One of the main problems of cultural heritages in all the different forms (buildings, monuments, painting) is their deterioration caused by natural and artificial decay processes. To address the conservation issue specific studies are required to determine, for example, origin, date, materials composition, technology processes involved, etc. The use of microanalysis techniques, in particular secondary ion mass spectrometry (SIMS), in the cultural heritage area has been demonstrated extremely useful to approach and provide this kind of information and support the experts involved in studies within this area (art historians, archaeologists, curators etc.). In this work, an up to date overview of possible SIMS applications to archaeological topics is given, pointing out the peculiarity and the main limitations and drawbacks of this analytical approach. One example of SIMS application to archaeological glasses is reported. Moreover the wide technique flexibility and its strength in combination with other complementary techniques are remarked. 相似文献
993.
Pilar Lafuente Juan J. Novoa Michael J. Bearpark Paolo Celani Massimo Olivucci Michael A. Robb 《Theoretical chemistry accounts》1999,102(1-6):309-316
The model proposed by Dougherty for the design of high-spin organic systems has been studied from a quantitative point of
view using a Heisenberg Hamiltonian formalism. This analysis leads to a decomposition of the phenomenological coupling parameter,
J, into contributions from individual active orbital sites and a decomposition of the spin multiplicity into terms from the
ferromagnetic coupling unit and the spin-containing units. An analysis of the origin of quintet stability has been carried
out for four molecular systems with quintet ground states that have previously been synthesized by Dougherty and by Adam.
The results indicate that the ferromagnetic coupling unit plays the dominant role in determining high-spin stability as suggested
by Dougherty and gives some insights that may be useful in the rational design of high-spin systems.
Received: 31 July 1998 / Accepted: 21 September 1998 / Published online: 23 February 1999 相似文献
994.
Laura Andreozzi Massimo Faetti Giancarlo Galli Marco Giordano Diego Palazzuoli 《Macromolecular Symposia》2004,218(1):323-332
The possibility of achieving devices for rewritable optical storage is provided by liquid-crystalline polymers with azobenzene side groups, because they undergo photochemically induced trans-cis reversible isomerization. In this work we overview our investigations into a nematic azobenzene-polymethacrylate (PMA4) as a suitable material for optical nanowriting. Relaxation processes over different time-length scales are discussed with particular reference to understanding the interplay between homogeneity at the molecular level, bit stability and working temperature range. 相似文献
995.
996.
997.
Adriana Trapani María ngeles Esteban Francesca Curci Daniela Erminia Manno Antonio Serra Giuseppe Fracchiolla Cristbal Espinosa-Ruiz Stefano Castellani Massimo Conese 《Molecules (Basel, Switzerland)》2022,27(2)
The supply of nutrients, such as antioxidant agents, to fish cells still represents a challenge in aquaculture. In this context, we investigated solid lipid nanoparticles (SLN) composed of a combination of Gelucire® 50/13 and Precirol® ATO5 to administer a grape seed extract (GSE) mixture containing several antioxidant compounds. The combination of the two lipids for the SLN formation resulted in colloids exhibiting mean particle sizes in the range 139–283 nm and zeta potential values in the range +25.6–43.4 mV. Raman spectra and X-ray diffraction evidenced structural differences between the free GSE and GSE-loaded SLN, leading to the conclusion that GSE alters the structure of the lipid nanocarriers. From a biological viewpoint, cell lines from gilthead seabream and European sea bass were exposed to different concentrations of GSE-SLN for 24 h. In general, at appropriate concentrations, GSE-SLN increased the viability of the fish cells. Furthermore, regarding the gene expression in those cells, the expression of antioxidant genes was upregulated, whereas the expression of hsp70 and other genes related to the cytoskeleton was downregulated. Hence, an SLN formulation containing Gelucire® 50/13/Precirol® ATO5 and GSE may represent a compelling platform for improving the viability and antioxidant properties of fish cells. 相似文献
998.
Carlo Ciarrocchi Donatella Sacchi Massimo Boiocchi Maduka Lankani Weththimuni Alessio Orbelli Biroli Maurizio Licchelli 《Molecules (Basel, Switzerland)》2022,27(6)
Copper(II) azacyclam complexes (azacyclam = 1,3,5,8,12-pentaazacyclotetradecane) containing naphthyl or dansyl subunits can be prepared by template synthesis involving proper sulfonamide derivatives as locking fragments. The macrocyclic complexes are very poorly emissive due to the fluorescence-quenching behavior displayed by Cu2+ ions. However, the fluorescence can be recovered as a result of the decomposition of the complexes, which induces the release of free light-emitting subunits to the solution. This reaction takes place very slowly in neutral water but its rate is increased by the presence of sulfite. Therefore, [Cu(azacyclam)]2+ derivatives have been investigated as simple chemical probes for the fluorogenic detection of sulfite both on laboratory and real samples. Preliminary tests performed on samples of white wine provided sulfite concentration values that are in agreement with those obtained by a standard analytical method. 相似文献
999.
Benevieri Pierluigi Calamai Alessandro Furi Massimo Pera Maria Patrizia 《Journal of Dynamics and Differential Equations》2022,34(1):555-581
We extend to the infinite dimensional context the link between two completely different topics recently highlighted by the authors: the classical eigenvalue problem for real square matrices and the Brouwer degree for maps between oriented finite dimensional real manifolds. Thanks to this extension, we solve a conjecture regarding global continuation in nonlinear spectral theory that we have formulated in a recent article. Our result (the ex conjecture) is applied to prove a Rabinowitz type global continuation property of the solutions to a perturbed motion equation containing an air resistance frictional force.
相似文献1000.