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61.
This paper deals with the photoluminescence temperature dependence of the zero-phonon lines of Cr(3+) ions in an yttrium aluminium garnet (YAG) matrix. Experimental data were analysed in the framework of electron-phonon coupling in the quadratic approximation and it was found that Cr(3+) ions in the YAG matrix are strongly coupled with lattice vibrations, with a Debye temperature of about 550 K and a value of the quadratic coupling constant of 0.65. The analysis of both homogeneous and inhomogeneous contributions to the photoluminescence linewidth is performed and the results obtained are compared with previously reported data for Fe(3+):YAG and discussed with respect to the different dependences of the two transition metal ions on the crystal field. 相似文献
62.
Highly stable gel electrolytes for dye solar cells based on chemically engineered polymethacrylic hosts 总被引:1,自引:0,他引:1
De Gregorio GL Agosta R Giannuzzi R Martina F De Marco L Manca M Gigli G 《Chemical communications (Cambridge, England)》2012,48(25):3109-3111
Four different species of ionically conductive polymers were synthesized and successfully implemented to formulate novel quasi-solid electrolytes for dye solar cells. A power conversion efficiency superior to 85% of the correspondent liquid electrolyte as well as an excellent cell's stability was demonstrated after 500 days of storage. 相似文献
63.
Jennilee M. A. Gavina Jessica Priem Carla M. Wood Chao Wu Xiao Yong-Lai Feng 《Analytical and bioanalytical chemistry》2013,405(8):2643-2651
Consumption and nutritional supplementation of soy and soy-based products have been linked to health benefits such as lower cholesterol and triglyceride levels, and decreased incidence of cardiovascular disease and diabetes. In this study, we have developed a sensitive, specific, and robust method using high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) for determination of serum isoflavones. A new highly efficient pentafluorophenyl phase core–shell column was first used to separate all isoflavones within 3 min, a separation time which is comparable to ultra-pressure liquid chromatography (UPLC) and micro-HPLC. A two-enzyme hydrolysis system with sulfatase and β-glucuronidase has also been developed to improve the efficiency of deconjugation of conjugated isoflavones in serum. The corresponding conjugated isoflavones were used to evaluate recoveries. In addition to duplicates, the method of standard addition was also applied in sample analysis for quality control. The developed method was applied to the analysis of 32 serum samples and was shown to be specific, sensitive and reproducible. 相似文献
64.
Manca P Pilo MI Sanna G Zucca A Bergamini G Ceroni P 《Chemical communications (Cambridge, England)》2011,47(12):3413-3415
Two Ru(2+) complexes containing terpyridine ligands appended with terthiophene units connected by a methyleneoxy or an alkynyl bridge show very different luminescent behaviours: the former is non-luminescent at 298 K owing to a photoinduced energy transfer process to the terthiophene moiety, while the latter exhibits an extraordinary long excited state lifetime because of an energy reservoir effect. 相似文献
65.
Bonniard L Kahlal S Diallo AK Ornelas C Roisnel T Manca G Rodrigues J Ruiz J Astruc D Saillard JY 《Inorganic chemistry》2011,50(1):114-124
Density functional theory (DFT) calculations on the model [{FeCp(dpe)}(2){1,4-C(6)H(4)(CN)(2)}](2+) (3(2+); dpe = diphosphinoethane) of salts of the cations [{FeCp(dppe)}(2){1,4-C(6)H(4)(CN)(2)}](2+) (1(2+); dppe = 1,2-bis[diphenyldiphosphino]ethane) and [{FeCp*(CO)(2)}(2){1,4-C(6)H(4)(CN)(2)}](2+) (2(2+)), for which the X-ray crystal structures have been determined, as well as on its isomer [{FeCp(dpe)}(2){1,3-C(6)H(4)(CN)(2)}](2+) (4(2+)) and on the related complex [{FeCp(dpe)}(3){1,3,5-C(6)H(3)(CN)(3)}](3+) (5(2+)), indicate that the highest occupied molecular orbitals (HOMOs) of these compounds are localized on the metal centers with negligible participation of the C(6) ring. Thus, the poly(nitrile)phenylene ligand efficiently quenches the electronic communication between the metal centers. This is at variance with the related isoelectronic polyacetylene phenylene complexes, in which the iron centers have been shown to be electronically coupled. Consistently, apart from the case of 3(3+), which shows some degree of delocalization, all of the oxidized forms of 3(2+), 4(2+), and 5(2+) can be described as class II, localized mixed-valent species, in agreement with the electrochemical data showing two close oxidation potentials around 1 V vs FeCp*(2). This is at variance with the p-phenylene-bridged biethynyldiiron analogue, for which extended electronic delocalization was earlier shown to provide greater degree of delocalization of the mixed valency. Time-dependent DFT calculations on 3(2+), 4(2+), and 5(2+) indicate that the lowest-energy absorption band is associated with metal-to-ligand charge-transfer transitions involving the metallic HOMOs and the two lowest unoccupied molecular orbitals that derive from the lowest π*(phenylene) orbitals with some π*(CN) bonding admixture. 相似文献
66.
Joke Vandenbergh Jeroen Dergent Bert Conings T.V.V. Gopala Krishna Wouter Maes Thomas J. Cleij Laurence Lutsen Jean Manca Dirk J.M. Vanderzande 《European Polymer Journal》2011,(9):1827-1835
Two hydrophilic branched oligo(ethylene glycol)-substituted PPV derivatives, poly(2,5-bis(1,3-bis(triethoxymethoxy)propan-2-yloxy)-1,4-phenylene vinylene) (BTEMP-PPV) and poly(2-methoxy-5-(1,3-bis(triethoxymethoxy)propan-2-yloxy)-1,4-phenylene vinylene) (MTEMP-PPV), are presented. Polymerizations have been performed via the dithiocarbamate precursor route, using lithium hexamethyldisilazide (LHMDS) as a base, to obtain high molecular weight precursor polymers. After thermal conversion of the precursor polymers into the fully conjugated systems, the solubility of the polymers has been examined. The polar nonionic side chains of MTEMP-PPV and BTEMP-PPV render the PPV backbone soluble in a variety of solvents, including alcohols and even water, making these polymers suitable candidates to be used in optoelectronic devices that can be processed from environmentally friendly solvent systems. 相似文献
67.
68.
Roberto Ambra Sonia Manca Guido Leoni Barbara Guantario Raffaella Canali Raffaella Comitato 《Molecules (Basel, Switzerland)》2021,26(1)
We previously demonstrated that apoptosis induced by tocotrienols (γ and δT3) in HeLa cells is preceded by Ca2+ release from the endoplasmic reticulum. This event is eventually followed by the induction of specific calcium-dependent signals, leading to the expression and activation of the gene encoding for the IRE1α protein and, in turn, to the alternative splicing of the pro-apoptotic protein sXbp1 and other molecules involved in the unfolded protein response, the core pathway coping with EndoR stress. Here, we showed that treatment with T3s induces the expression of a specific set of miRNAs in HeLa cells. Data interrogation based on the intersection of this set of miRNAs with a set of genes previously differentially expressed after γT3 treatment provided a few miRNA candidates to be the effectors of EndoR-stress-induced apoptosis. To identify the best candidate to act as the effector of the Xbp1-mediated apoptotic response to γT3, we performed in silico analysis based on the evaluation of the highest ∆ in Gibbs energy of different mRNA–miRNA–Argonaute (AGO) protein complexes. The involvement of the best candidate identified in silico, miR-190b, in Xbp1 splicing was confirmed in vitro using T3-treated cells pre-incubated with the specific miRNA inhibitor, providing a preliminary indication of its role as an effector of EndoR-stress-induced apoptosis. 相似文献
69.
Guglielmo DAmico Montserrat Guillen Raimondo Manca 《Insurance: Mathematics and Economics》2009,45(2):173-179
In this paper a stochastic model for disability insurance contracts is presented. The model is based on a discrete time non-homogeneous semi-Markov process to which the backward recurrence time process is joined. This permits us to study in a more complete way the disability evolution and to face the duration problem in a more effective way. The model is applied to a sample of contracts drawn at random from a mutual insurance company. 相似文献
70.
Manufacturing of multilayer thin films deposited on a glass substrate can be accomplished by means of pulsed laser sources.
Thermal and optical nonlinearities are induced during transient heating, since the response of weakly absorbing thin films
depends on the temperature. The heat source can either directly impinge the film surface,␣front treatment, or the glass substrate,
back treatment. In this paper a one-dimensional conjugate non-linear thermal-optical time dependent problem is numerically
analysed. The investigation is accomplished in order to compare the two processes. For a Nd-YAG laser with wavelength of 1064
nm, a a-Si/TCO and Al/a-Si/TCO multilayers are investigated. Results are presented in form of spatial and temporal temperature
profiles as well as absorbed heat transfer rates inside the layers. The accomplished analysis clearly shows that the back
treatment is more efficient in terms of manufacturing process, oriented to the production of photovoltaic cells.
Received on 4 November 1997 相似文献