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91.
Fernando C. Moraes Lucia H. Mascaro Sergio A. S. Machado Christopher M. A. Brett 《Electroanalysis》2010,22(14):1586-1591
A copper phthalocyanine/multiwalled carbon nanotube film‐modified glassy carbon electrode has been used for the determination of the herbicide glyphosate (Gly) at ?50 mV vs. SCE by electrochemical oxidation using differential pulse voltammetry (DPV). Cyclic voltammetry and electrochemical impedance spectroscopy showed that Gly is adsorbed on the metallic centre of the copper phthalocyanine molecule, with formation of Gly‐copper ion complexes. An analytical method was developed using DPV in pH 7.4 phosphate buffer solution, without any pretreatment steps: Gly was determined in the concentration range of 0.83–9.90 μmol L?1, with detection limit 12.2 nmol L?1 (2.02 μg L?1). 相似文献
92.
Aline Machado de Castro Kelly Cristina Nascimento Rodrigues Pedro Juliana Cunha da Cruz Marcela Costa Ferreira Selma Gomes Ferreira Leite Nei Pereira 《Applied biochemistry and biotechnology》2010,162(7):2111-2122
Sugarcane bagasse is an agroindustrial residue generated in large amounts in Brazil. This biomass can be used for the production
of cellulases, aiming at their use in second-generation processes for bioethanol production. Therefore, this work reports
the ability of a fungal strain, Trichoderma harzianum IOC-4038, to produce cellulases on a novel material, xylan free and cellulose rich, generated from sugarcane bagasse, named
partially delignified cellulignin. The extract produced by T. harzianum under submerged conditions reached 745, 97, and 559 U L−1 of β-glucosidase, FPase, and endoglucanase activities, respectively. The partial characterization of this enzyme complex
indicated, using a dual analysis, that the optimal pH values for the biocatalysis ranged from 4.9 to 5.2 and optimal temperatures
were between 47 and 54 °C, depending on the activity studied. Thermal stability analyses revealed no significant decrease
in activity at 37 °C during 23 h of incubation. When compared to model strains, Aspergillus niger ATCC-16404 and Trichoderma reesei RutC30, T. harzianum fermentation was faster and its extract showed a better balanced enzyme complex, with adequate characteristics for its application
in simultaneous saccharification and fermentation processes. 相似文献
93.
Garcia JC Justo JF Machado WV Assali LV 《The journal of physical chemistry. A》2010,114(44):11977-11983
We performed a first principles total energy investigation on the structural, electronic, and vibrational properties of adamantane molecules, functionalized with amine and ethanamine groups. We computed the vibrational signatures of amantadine and rimantadine isomers with the functional groups bonded to different carbon sites. By comparing our results with recent infrared and Raman spectroscopic data, we discuss the possible presence of different isomers in experimental samples. 相似文献
94.
J. Agostinho Moreira A. Almeida M.R. Chaves J.M. Machado da Silva S.M.F. Vilela 《Solid State Communications》2011,151(5):368-371
This work reports an experimental investigation of the ferroelectric character of magnetic phases of the orthorhombic Eu1−xY xMnO3 system at low temperatures. The temperature dependence of the polarization curves clearly reveals the existence of a re-entrant improper ferroelectric phase for x=0.2, 0.3 and 0.5. A ferroelectric phase is also stable for x=0.4, and we have no experimental evidence for its vanishing down to 7 K. From these and early results obtained using other experimental techniques, the corresponding (x,T) phase diagram was traced, yielding significant differences with regard to the ones previously reported. 相似文献
95.
J.A. Tenreiro Machado 《Optimization》2014,63(8):1167-1179
96.
Carlos J. G. Machado J. D. Pérez I. Jeong Y. J. Suh 《Annali di Matematica Pura ed Applicata》2014,193(2):591-608
In this paper, we give non-existence theorems for Hopf hypersurfaces in complex two-plane Grassmannians $G_2(\mathbb{C }^{m+2})$ with $\mathfrak D $ -parallel normal Jacobi operator ${\bar{R}}_N$ and $\mathfrak D $ -parallel structure Jacobi operator $R_{\xi }$ if the distribution $\mathfrak D $ or $\mathfrak D ^{\bot }$ component of the Reeb vector field is invariant by the shape operator, respectively. 相似文献
97.
Robert Reys Barbara Reys Gran Emanuelsson Bengt Johansson Alistair McIntosh Der Ching Yang 《School science and mathematics》1999,99(2):61-70
This paper reports selected findings from a study of number sense proficiency of students aged 8 to 14 years in Australia, Sweden, United States, and Taiwan. It comments on the meaning and importance of number sense, the development of the assessment instruments, and student responses to the items. Some implications for classrooms of the findings are then discussed. 相似文献
98.
Fractional derivatives: Probability interpretation and frequency response of rational approximations
J.A. Tenreiro Machado 《Communications in Nonlinear Science & Numerical Simulation》2009,14(9-10):3492-3497
The theory of fractional calculus (FC) is a useful mathematical tool in many applied sciences. Nevertheless, only in the last decades researchers were motivated for the adoption of the FC concepts. There are several reasons for this state of affairs, namely the co-existence of different definitions and interpretations, and the necessity of approximation methods for the real time calculation of fractional derivatives (FDs). In a first part, this paper introduces a probabilistic interpretation of the fractional derivative based on the Grünwald-Letnikov definition. In a second part, the calculation of fractional derivatives through Padé fraction approximations is analyzed. It is observed that the probabilistic interpretation and the frequency response of fraction approximations of FDs reveal a clear correlation between both concepts. 相似文献
99.
Fractional calculus generalizes integer order derivatives and integrals. Memristor systems generalize the notion of electrical elements. Both concepts were shown to model important classes of phenomena. This paper goes a step further by embedding both tools in a generalization considering complex-order objects. Two complex operators leading to real-valued results are proposed. The proposed class of models generate a broad universe of elements. Several combinations of values are tested and the corresponding dynamical behavior is analyzed. 相似文献
100.
Ronaldo Giro Liliana Y. A. Davila Angelita M. Machado Marilia J. Caldas Leni Akcelrud 《International journal of quantum chemistry》2010,110(4):885-892
We focus this work on the theoretical investigation of the block‐copolymer poly[oxyoctyleneoxy‐(2,6‐dimethoxy‐1,4phenylene‐1,2‐ethinylene‐phenanthrene‐2,4diyl) named as LaPPS19, recently proposed for optoelectronic applications. We used for that a variety of methods, from molecular mechanics to quantum semiempirical techniques (AM1, ZINDO/S‐CIS). Our results show that as expected isolated LaPPS19 chains present relevant electron localization over the phenanthrene group. We found, however, that LaPPS19 could assemble in a π‐stacked form, leading to impressive interchain interaction; the stacking induces electronic delocalization between neighbor chains and introduces new states below the phenanthrene‐related absorption; these results allowed us to associate the red‐shift of the absorption edge, seen in the experimental results, to spontaneous π‐stack aggregation of the chains. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献