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191.
J.L. Meunier A. Morel 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(2):341-352
For the first order transition of the Ising model below , Isakov has proven that the free energy possesses an essential singularity in the applied field. Such a singularity in the
control parameter, anticipated by condensation theory, is believed to be a generic feature of first order transitions, but
too weak to be observable. We study these issues for the temperature driven transition of the q states 2D Potts model at . Adapting the droplet model to this case, we relate its parameters to the critical properties at and confront the free energy to the many informations brought by previous works. The essential singularity predicted at the
transition temperature leads to observable effects in numerical data. On a finite lattice, a metastability domain of temperatures
is identified, which shrinks to zero in the thermodynamical limit.
Received 30 March 1999 相似文献
192.
Milena Hugenschmidt Ksenia Kutonova Elvia P. Valadez Sánchez Sarah Moulai Hartmut Gliemann Stefan Bräse Christof Wöll Dagmar Gerthsen 《Particle & Particle Systems Characterization》2020,37(11):2000209
The first example of layer-by-layer growth of a metal–organic framework (MOF) directly on transmission electron microscopy (TEM) grids is described. ZIF-8 is deposited on thin amorphous carbon films and subjected to a structure analysis by (scanning) TEM ((S)TEM). This method serves as a two-in-one synthesis and TEM sample-preparation technique and allows straightforward analysis of ZIF-8 crystallites. Artifacts resulting from sample preparation are completely avoided by this approach. The morphological properties, crystal structure, and the chemical composition of the material are investigated with high spatial resolution by a variety of methods of (analytical) electron microscopy. Furthermore, the incorporation of metallic nanoparticles in ZIF-8 by integrating a corresponding step into the layer-by-layer deposition process is examined. The formation of ZIF-8 crystals on the film proceeds as under the absence of nanoparticle-forming synthesis steps. However, the nanoparticles rather cover the supporting amorphous carbon film than being incorporated in the ZIF-8 material. This information cannot be obtained from standard characterization techniques but requires the application of analytical (S)TEM techniques. 相似文献
193.
Mignani AG Ciaccheri L Ottevaere H Thienpont H Conte L Marega M Cichelli A Attilio C Cimato A 《Analytical and bioanalytical chemistry》2011,399(3):1315-1324
Because of its high price, extra virgin olive oil is frequently targeted for adulteration with lower quality oils. This paper
presents an innovative optical technique capable of quantifying and discriminating the adulteration of extra virgin olive
oil caused by lower-grade olive oils. An original set-up for diffuse-light absorption spectroscopy in the wide 400–1,700 nm
spectral range was experimented. It made use of an integrating sphere containing the oil sample and of optical fibers for
illumination and detection; it provided intrinsically scattering-free absorption spectroscopy measurements. This set-up was
used to collect spectroscopic fingerprints of authentic extra virgin olive oils from the Italian Tuscany region, adulterated
by different concentrations of olive-pomace oil, refined olive oil, deodorized olive oil, and refined olive-pomace oil. Then,
a straightforward multivariate processing of spectroscopic data based on principal component analysis and linear discriminant
analysis was applied which was successfully capable of predicting the fraction of adulterant in the mixture, and of discriminating
its type. The results achieved by means of optical spectroscopy were compared with the analysis of fatty acids, which was
carried out by standard gas chromatography. 相似文献
194.
Aleksandra Krstic Aleksandar Pavic Edina Avdovic Zoran Markovic Milena Stevanovic Isidora Petrovic 《Molecules (Basel, Switzerland)》2022,27(7)
Pancreatic carcinoma still represents one of the most lethal malignant diseases in the world although some progress has been made in treating the disease in the past decades. Current multi-agent treatment options have improved the overall survival of patients, however, more effective treatment strategies are still needed. In this paper we have characterized the anticancer potential of coumarin-palladium(II) complex against pancreatic carcinoma cells. Cells viability, colony formation and migratory potential of pancreatic carcinoma cells were assessed in vitro, followed by evaluation of apoptosis induction and in vivo testing on zebrafish. Presented results showed remarkable reduction in pancreatic carcinoma cells growth both in vitro and in vivo, being effective at micromolar concentrations (0.5 μM). Treatments induced apoptosis, increased BAX/BCL-2 ratio and suppressed the expression of SOX9 and SOX18, genes shown to be significantly up-regulated in pancreatic ductal adenocarcinoma. Importantly, treatments of the zebrafish-pancreatic adenocarcinoma xenografts resulted in significant reduction in tumor mass, without provoking any adverse toxic effects including hepatotoxicity. Presented results indicate the great potential of the tested compound and the perspective of its further development towards pancreatic cancer therapy. 相似文献
195.
Ralitsa Chimshirova Milena Popova Amina Chakir Violeta Valcheva Simeon Dimitrov Boryana Trusheva Abderrahmane Romane Vassya Bankova 《Molecules (Basel, Switzerland)》2022,27(7)
The chemical composition and antimicrobial activity of propolis from a semi-arid region of Morocco were investigated. Fifteen compounds, including triterpenoids (1, 2, 7–12), macrocyclic diterpenes of ingol type (3–6) and aromatic derivatives (13–15), were isolated by various chromatographic methods. Their structures were elucidated by a combination of spectroscopic and chiroptical methods. Compounds 1 and 3 are new natural compounds, and 2, 4–6, and 9–11 are newly isolated from propolis. Moreover, the full nuclear magnetic resonance (NMR) assignments of three of the known compounds (2, 4 and 5) were reported for the first time. Most of the compounds tested, especially the diterpenes 3, 4, and 6, exhibited very good activity against different strains of bacteria and fungi. Compound 3 showed the strongest activity with minimum inhibitory concentrations (MICs) in the range of 4–64 µg/mL. The combination of isolated triterpenoids and ingol diterpenes was found to be characteristic for Euphorbia spp., and Euphorbia officinarum subsp. echinus could be suggested as a probable and new plant source of propolis. 相似文献
196.
197.
198.
We study the breakdown of chiral invariance by calculating, in the infinite coupling, large-N limit, the generating functional of a U(N) gauge theory with one fermion, expressed on a lattice with the naive, chiral symmetric action. We compute the link integral over the gauge fields and the expression obtained after the integration over the fermions is recast under the form of a generating functional for bosonic fields. Then, a saddle-point method allows the calculation of the order parameter for which a non-zero value signals the spontaneous breakdown of chiral symmetry. The analysis of the fluctuations around the saddle point allows one to exhibit the Goldstone modes corresponding to those global symmetries of the fermionic lattice action which are simultaneously broken. 相似文献
199.
B. Gabioud J.-C. Alder C. Joseph J.-F. Loude N. Morel A. Perrenoud J.-P. Perroud M.T. Trân E. Winkelmann W. Dahme H. Panke D. Renker G. Strassner P. Truöl G.F. de Téramond 《Physics letters. [Part B]》1981,103(1):9-12
Notable improvements in the treatment of the reaction π?d→γnn, extending the validity of the calculation to lower photon energies, permit a new analysis of a high statistics photon spectrum. A precise value of the effective range parameter γnn = 2.83 ± 0.11 fm has been obtained. The theoretical uncertainty is 0.11 fm. The value of the scattering length previously extracted from the same spectrum is confirmed, with ann = ? 18.6 ± 0.5 fm. 相似文献
200.
J. Fischer P. Extermann O. Guisan R. Mermod B. Morel L. Rosselet R. Sachot P. Bloch G. Bunce B. Devaux A.M. Diamant-Berger N. Do-Duc G. Marel R. Turlay 《Physics letters. [Part B]》1978,73(3):364-368
We have observed for the first time the very rare π0 → e+e? decay. The tagged π0's come from K+ → π+π0 decays in flight. We find the branching ratio to be (2.23?1.1+2.4) × 10?7 (90% C.L.). This value is well above the QED unitary limit and comes in rough agreement with a second-order electromagnetic process mediated by vector mesons. 相似文献