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81.
Aires da Conceição Silva Lucia C.S. Aguiar Andréa Luzia F. de Souza Luiz Fernando Brum Malta 《Tetrahedron letters》2010,51(30):3883-6491
In this work, we present ligand-free Suzuki cross-coupling reactions in PEG 300 under thermal conditions at 55 °C with good yields of conversion; better results were obtained with low reaction time. In 1 hour, 1-iodo-4-nitrobenzene and phenylboronic acid reached 98% of the yield and 9700 of TON. Better results were obtained with Pd(0) sources. The reaction system was recycled up to three times with good activity. 相似文献
82.
Filgueira Dde M Guterres LP Votto AP Vargas MA Boyle RT Trindade GS Nery LE 《Photochemistry and photobiology》2010,86(6):1278-1284
The purpose of this study was to verify the occurrence of pigment dispersion in retinal pigment cells exposed to UVA and UVB radiation, and to investigate the possible participation of a nitric oxide (NO) pathway. Retinal pigment cells from Neohelice granulata were obtained by cellular dissociation. Cells were analyzed for 30 min in the dark (control) and then exposed to 1.1 and 3.3 J cm−2 UVA, 0.07 and 0.9 J cm−2 UVB, 20 n m β-PDH (pigment dispersing hormone) or 10 μ m SIN-1 (NO donor). Histological analyses were performed to verify the UV effect in vivo . Cultured cells were exposed to 250 μ m L-NAME (NO synthase blocker) and afterwards were treated with UVA, UVB or β-PDH. The retinal cells in culture displayed significant pigment dispersion in response to UVA, UVB and β-PDH. The same responses to UVA and UVB were observed in vivo . SIN-1 did not induce pigment dispersion in the cell cultures. l-NAME significantly decreased the pigment dispersion induced by UVA and UVB but not by β-PDH. All retinal cells showed an immunopositive reaction against neuronal nitric oxide synthases. Therefore, UVA and UVB radiation are capable of inducing pigment dispersion in retinal pigment cells of Neohelice granulata and this dispersion may be nitric oxide synthase dependent. 相似文献
83.
Mario Ribeiro de Melo-Júnior Jorge Luiz Silva Araújo-Filho Consuelo Antunes Barreto Lins Nicodemos Teles de Pontes-Filho Luiz Bezerra de CarvalhoJr 《Applied biochemistry and biotechnology》2010,160(8):2198-2207
This work aimed to immobilize the antibody anti-galectin-3 onto polysiloxane–polyvinyl alcohol (POS-PVA) support, to evaluate
its capacity to capture the serum antigen galectin-3 and to quantify by ELISA the antigen levels in sera from patients with
prostatic adenocarcinoma (PA) and benign prostatic hyperplasia (BPH) and healthy individuals. Also, for comparative effect,
the galectin-3 expression in the prostate tissue through immunohistochemistry was evaluated. The optical density (galectin-3
level) values established for the sera from PA and BPH patients were lower compared with those found for the healthy individuals.
Galectin-3 immunohistochemically showed a significant increase and reduction of the cytoplasmatic protein expression in BPH
and PA, respectively, compared with the normal prostate. These results showed that POS-PVA disks could be used as solid phase
to immobilize serum galectins and in immunoassays procedures for the correspondent IgG anti-galectins detection in human sera. 相似文献
84.
Puebla P Oshima-Franco Y Franco LM Santos MG Silva RV Rubem-Mauro L Feliciano AS 《Molecules (Basel, Switzerland)》2010,15(11):8193-8204
The effect of four sub-extracts prepared from the lyophilized hydroalcoholic bark of Dipteryx alata (Leguminosae-Papilionoideae) dissolved in a methanol-water (80:20) mixture through a liquid-liquid partition procedure has been investigated against the neuromuscular blockade of the venom of the snake Bothrops jararacussu. The active CH?Cl? sub-extract has been extensively analyzed for its chemical constituents, resulting in the isolation of four lupane-type triterpenoids: lupeol, lupenone, 28-hydroxylup-20(29)-en-3-one, betulin, nine isoflavonoids: 8-O-methylretusin, 7-hydroxy-5,6,4'-trimethoxyisoflavone, afrormosin, 7-hydroxy-8,3',4'-trimethoxyisoflavone, 7,3'-dihydroxy-8,4'-dimethoxyisoflavone, odoratin, 7,8,3'-trihydroxy-4'-methoxyisoflavone, 7,8,3'-trihydroxy-6,4'-dimethoxyisoflavone, dipteryxin, one chalcone: isoliquiritigenin, one aurone: sulfuretin and three phenolic compounds: vanillic acid, vanillin, and protocatechuic acid. Their chemical structures were elucidated on the basis of spectroscopic analysis, including HRMS, 1D- and 2D-NMR techniques. 相似文献
85.
Mariana R. Almeida Rafael S. Alves Laura B. L. R. Nascimbem Rodrigo Stephani Ronei J. Poppi Luiz Fernando C. de Oliveira 《Analytical and bioanalytical chemistry》2010,397(7):2693-2701
Fourier transform Raman spectroscopy and chemometric tools have been used for exploratory analysis of pure corn and cassava starch samples and mixtures of both starches, as well as for the quantification of amylose content in corn and cassava starch samples. The exploratory analysis using principal component analysis shows that two natural groups of similar samples can be obtained, according to the amylose content, and consequently the botanical origins. The Raman band at 480 cm?1, assigned to the ring vibration of starches, has the major contribution to the separation of the corn and cassava starch samples. This region was used as a marker to identify the presence of starch in different samples, as well as to characterize amylose and amylopectin. Two calibration models were developed based on partial least squares regression involving pure corn and cassava, and a third model with both starch samples was also built; the results were compared with the results of the standard colorimetric method. The samples were separated into two groups of calibration and validation by employing the Kennard-Stone algorithm and the optimum number of latent variables was chosen by the root mean square error of cross-validation obtained from the calibration set by internal validation (leave one out). The performance of each model was evaluated by the root mean square errors of calibration and prediction, and the results obtained indicate that Fourier transform Raman spectroscopy can be used for rapid determination of apparent amylose in starch samples with prediction errors similar to those of the standard method. Figure
Raman spectroscopy has been successfully applied to the determination of the amylose content in cassava and corn starches by means of multivariate calibration analysis. 相似文献
86.
Andressa H. de Morais Batista Francisco F. de Sousa Sara B. Honorato Alejandro P. Ayala Josue M. Filho Francisco W. de Sousa Antonio N. Pinheiro J.C.S. de Araujo Ronaldo F. Nascimento Antoninho Valentini Alcineia C. Oliveira 《Journal of molecular catalysis. A, Chemical》2010,315(1):86-98
Isomorphously substituted (MeDM) and impregnated metal-containing MCM-41 (MeOx/IM) catalysts, in which Me = Co, Cu, Cr, Fe or Ni, have been prepared. Structural and textural characterizations of the catalysts were performed by means of X-ray diffraction (XRD), chemical analysis, Raman spectroscopy, electron paramagnetic resonance (EPR), N2 adsorption isotherms and temperature programmed reduction (TPR). Cu2+, Co2+, and Cr4+/Cr3+ species were found over the catalysts as cations incorporated in the MCM-41 structure (MeDM) or highly dispersed oxides on the surface (MeOx/IM). The MeDM catalysts exhibited a good performance in the dehydrogenation of ethylbenzene with CO2. However, MeOx/IM catalysts had a low performance in styrene production (activity less than 15 × 10?3 mmol h?1 and selectivity for styrene less than 80%) due to the high reducibility of the metals species. However, Ni2+ or Fe3+ coordinated with the MCM-41 framework, as well as NiOx and Fe2O3 extra-framework species, is continuously oxidized by the CO2 to maintain the active sites for dehydrogenating ethylbenzene. Deactivation studies on the FeDM sample showed that Fe3+ species produced active sp2 carbon compounds, which are removed by CO2; the referred sample is catalytically selective for styrene and stable over 24 h of reaction. In contrast, highly active Ni2+ and Ni0 species produced a large amount of polyaromatic carbonaceous deposits from styrene, as identified by TPO, TG and Raman spectroscopy. An acid–base mechanism is proposed to operate to adsorb ethylbenzene and abstract the β-hydrogen. CO2 plays a role in furnishing the lattice oxygen to maintain the Fe3+ active sites in the dehydrogenation of ethylbenzene to form styrene. 相似文献
87.
The wavelet transform has been shown to be a useful tool for multivariate calibration. However, the choice of wavelet transform settings (wavelet family, length and number of decomposition levels) for a given application is still an open problem. The present paper proposes an alternative approach, which consists of generating an ensemble model by combining individual models obtained with different wavelet transform settings. The advantages of the proposed method are demonstrated in two analytical problems, namely the determination of moisture and protein in wheat by near infrared spectroscopy and the determination of specific mass and three distillation temperatures (T10, T50, T90) in gasoline by middle infrared spectroscopy. In these problems, the results varied considerably among individual models, which underlines the risk associated to an inadequate choice of wavelet transform settings. In contrast, the ensemble model always provided adequate results in terms of prediction error and noise sensitivity. The proposed method can be seen as an advantageous alternative for multivariate calibration in the wavelet domain, as it frees the analyst from the need to choose a particular configuration for the wavelet transform. 相似文献
88.
André Luiz Tessaro Vagner Roberto Batistela Augusto César Gracetto Hueder Paulo Moisés de Oliveira Rosana Lazara Sernaglia Vagner Roberto de Souza Wilker Caetano Noboru Hioka 《Journal of Physical Organic Chemistry》2011,24(2):155-161
Benzoporphyrin monoacid derivatives, here named B3A and B3B, are promising new drugs for photodynamic therapy. Although both isomers show interesting characteristics as photosensitizing compounds, they have some distinct physicochemical properties such as the tendency to self‐aggregate in water‐rich media. Because pH drives the presence of each species, the pKa of these compounds assumes strategic importance. However, traditional micro‐titration methods and UV–Vis absorption techniques fail to give reliable pKa values due to the characteristics of this highly complex system, such as the precipitation of hydrophobic species, close pKa values, and high absorption band superposition. In the present work, chemometric tools are employed to evaluate pKa, and the kinetic tendency of monomers to undergo self‐aggregation is investigated. In solvent mixtures at low water percentage in ethanol, both B3A and B3B are stabilized in a monomeric state. However, in mixtures with a high water content, self‐aggregation takes place, mainly under a mild pH acid condition (3 < pH < 6), in which the prevalent protolytic species of both isomers is the neutral charged form, compounds with carboxylic and porphyrin free‐base groups. It is demonstrated that both isomers can undergo aggregation following a self‐catalytic mechanism, which is 2000 times slower to B3A than B3B. For B3A, the aggregation is manifested by a decrease in the monomer band with the aggregation band probably superposed to that of the monomer. For B3B, together with the decrease in the monomer band, a new band related to self‐aggregates is observed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
89.
90.
Ademir Aparecido Constantino Dario Landa-Silva Everton Luiz de Melo Candido Ferreira Xavier de Mendonça Douglas Baroni Rizzato Wesley Romão 《Annals of Operations Research》2014,218(1):165-183
This paper tackles a Nurse Scheduling Problem which consists of generating work schedules for a set of nurses while considering their shift preferences and other requirements. The objective is to maximize the satisfaction of nurses’ preferences and minimize the violation of soft constraints. This paper presents a new deterministic heuristic algorithm, called MAPA (multi-assignment problem-based algorithm), which is based on successive resolutions of the assignment problem. The algorithm has two phases: a constructive phase and an improvement phase. The constructive phase builds a full schedule by solving successive assignment problems, one for each day in the planning period. The improvement phase uses a couple of procedures that re-solve assignment problems to produce a better schedule. Given the deterministic nature of this algorithm, the same schedule is obtained each time that the algorithm is applied to the same problem instance. The performance of MAPA is benchmarked against published results for almost 250,000 instances from the NSPLib dataset. In most cases, particularly on large instances of the problem, the results produced by MAPA are better when compared to best-known solutions from the literature. The experiments reported here also show that the MAPA algorithm finds more feasible solutions compared with other algorithms in the literature, which suggest that this proposed approach is effective and robust. 相似文献