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71.
Antonio Da Settimo Anna Maria Marini Giampaolo Primofiore Federico Da Settimo Silvia Salerno Concettina La Motta Gianluca Pardi Pier Luigi Ferrarini Claudio Mori 《Journal of heterocyclic chemistry》2000,37(2):379-382
The synthesis of the title compounds 5H, 11H‐pyrido[2′,3′:2,3]thiopyrano[4,3‐b]indoles was accomplished by the Fischer indole cyclization of some 2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one phenylhydrazones and 7‐methyl‐2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one phenylhydrazones. The synthesis of the new 2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one, which was used as one of the starting compounds, is also described. 相似文献
72.
Poynor A. N. Cumblidge S. E. Rasera R. L. Catchen G. L. Motta A. T. 《Hyperfine Interactions》2001,136(3-8):549-553
We have measured nuclear electric–quadrupole interactions (EQI) at 181Ta impurities substituted as Hf atoms into the Zr site in Zr2Ni. Using perturbed-angular-correlation (PAC) spectroscopy, we measured the EQI over temperatures ranging from 10 to 1200
K. Over the entire range of temperature, the Zr2Ni crystal has a bct Al2Cu structure that includes a single Zr site. The crystal field symmetry surrounding this site is rather low, giving rise to
a highly asymmetric electric-field gradient tensor. At 10 K, the EQI is characterized by an angular frequency ω0=601(3) Mrad s−1, and an asymmetry parameter η=0.835(2). At 1200 K, ω0 decreases to 516(3) Mrad s−1, and η also decreases to 0.790(4). Although weak, the temperature dependence of ω0 is consistent with a (1−BT
3/2) power law, in which B=6×10−6 K−3/2. The EQI also manifests a very narrow linewidth. We observed no evidence either for magnetic ordering or for structural phase
transitions in the temperature range covered by this experiment. Moreover, the sharpness of the EQI indicates that the samples
as prepared are remarkably free of strain and defects. These results indicate that the Zr2Ni structure does not promote the formation of defects and that the power-law dependence of ω0 on T is insensitive to the asymmetric nature of the crystal.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
73.
Antonio Da Settimo Giampaolo Primofiore Anna Maria Marini Federico Da Settimo Concettina La Motta Silvia Salerno 《Journal of heterocyclic chemistry》1999,36(3):639-642
The preparation of two new heterocyclic ring systems, purinobenzodiazepine and purinobenzotriazocine derivatives by the condensation of 8-aminotheophylline or 8-hydrazinotheophylline with o-carboxybenzaldehyde or o-carboxyacetophenone is described. 相似文献
74.
In this paper we investigate via a dynamic programming approach some nonlinear stochastic control problems where the control
set is unbounded and a classical coercivity hypothesis is replaced by some weaker assumptions. We prove that these problems
can be approximated by finite fuel problems; show the continuity of the relative value functions and characterize them as
unique viscosity solutions of a quasi-variational inequality with suitable boundary conditions. 相似文献
75.
Let ? and ?′ be alternative rings. We study the additivity of n-multiplicative isomorphisms from ? onto ?′ and of n-multiplicative derivations of ?. We prove that, if ? contains a family of nontrivial idempotents satisfying Martindale's conditions, then these two maps are additives. 相似文献
76.
77.
Felipe Augusto Ferrari Fernanda Lopes Motta Reinaldo Gaspar Bastos Maria Helena Andrade Santana 《Applied biochemistry and biotechnology》2013,170(6):1491-1502
Hyaluronic acid (HA) is a biopolymer with important applications in the pharmaceutical, medical, and cosmetic fields. This work explores the potentialities of a cylindrical polyurethane foam dowel with central aeration as a novel packed bed bioreactor for the production of HA. The goals were to provide a large surface area for oxygen transfer through the patches of liquid film that form in the pores of the foam in which cell proliferation and HA production occur and to easily recover the HA produced. The resulting yields of HA/cell were higher than 1, and the produced HA was completely recovered by pressing the foam. The external conditions that inhibit catabolism, the deviation of energetic metabolism toward the production of HA, were modulated by aeration and the initial glucose concentration. The production of HA was reproducible in 12 successive fermentation cycles. These findings contribute to the development of efficient strategies for the controlled production and recovery of HA. 相似文献
78.
Europium(III) Concentration Effect on the Spectroscopic and Photoluminescent Properties of BaMoO4:Eu
Ieda L. V. Rosa Ana Paula A. Marques Marcos T. S. Tanaka Fabiana V. Motta José A. Varela Edson R. Leite Elson Longo 《Journal of fluorescence》2009,19(3):495-500
BaMoO4:Eu (BEMO) powders were synthesized by the polymeric precursor method (PPM), heat treated at 800 °C for 2 h in a heating rate
of 5 °C/min and characterized by powder X-ray diffraction patterns (XRD), Fourier Transform Infra-Red (FTIR) and Raman spectroscopy,
besides room temperature Photoluminescence (PL) measurements. The emission spectra of BEMO samples under excitation of 394 nm
present the characteristic Eu3+ transitions. The relative intensities of the Eu3+ emissions increase as the concentration of this ion increases from 0.01 to 0.075 mol, but the luminescence is drastically
quenched for the Ba0.855Eu0.145MoO4 sample. The one exponential decay curves of the Eu3+ 5D0→7F2 transition, λ
exc = 394 nm and λ
em = 614 nm, provided the decay times of around 0.54 ms for all samples. It was observed a broadening of the Bragg reflections
and Raman bands when the Eu+3 concentration increases as a consequence of a more disordered material. The presence of MoO3 and Eu2Mo2O7 as additional phases in the BEMO samples where observed when the Eu3+ concentration was 14.5 mol%. 相似文献
79.
Di Bella S Condorelli GG Motta A Ustione A Cricenti A 《Langmuir : the ACS journal of surfaces and colloids》2006,22(19):7952-7955
The synthesis and structure of a dipolar nonlinear optical bis(salicylaldiminato)Ni(II)-derivatized Schiff base complex chemisorbed on H-terminated Si(100) surfaces is reported. The existence of a monolayer of the derivatized complex chemisorbed on the Si(100) surface is unambiguously confirmed by high-resolution core-level XPS and AFM/SNOM analyses. The comparison between the optical SNOM images highlights the contribution of the monolayer to the local reflectivity of the sample. Angle-resolved XPS data indicate the presence of chlorine head atoms on the monolayer surface. Altogether, XPS and AFM/SNOM data suggest the formation of a nanoscale uniform, homogeneous, complete, ordered monolayer self-assembled on the Si(100) surface. 相似文献
80.
Jiazhen Chen Alessandro Motta Binghao Wang Yanshan Gao Tobin J. Marks 《Angewandte Chemie (International ed. in English)》2019,58(21):7030-7034
In principal, the direct copolymerization of ethylene with polar comonomers should be the most efficient means to introduce functional groups into conventional polyolefins but remains a formidable challenge. Despite the tremendous advances in group 4‐centered catalysis for olefin polymerization, successful examples of ethylene + polar monomer copolymerization are rare, especially without Lewis acidic masking reagents. Here we report that certain group 4 catalysts are very effective for ethylene + CH2=CH(CH2)nNR2 copolymerizations with activities up to 3400 Kg copolymer mol?1‐Zr h‐1 atm‐1, and with comonomer enchainment up to 5.5 mol % in the absence of masking reagents. Group 4 catalyst‐amino‐olefin structure–activity‐selectivity relationships reflect the preference of olefin activation over free amine coordination, which is supported by mechanistic experiments and DFT analysis. These results illuminate poorly understood facets of d0 metal‐catalyzed polar olefin monomer copolymerization processes. 相似文献