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81.
Sergio Carvalho de Santana Raimundo Cosme da Silva Filho Jorge dos Santos Cavalcanti Jackson Araujo de Oliveira Gorete Ribeiro de Macedo Francine Ferreira Padilha Everaldo Silvino dos Santos 《Korean Journal of Chemical Engineering》2014,31(4):684-691
A mathematical model was developed to predict breakthrough curves during purification of the two chitosanases from Metarhizium anisopliae by expanded bed adsorption, taking into account the axial dispersion of liquid and using Streamline DEAE and SP XL adsorbents, anion and cation exchange resins, respectively. All the experiments were performed without clarification (with cells) aiming at the reduction of unit operations in future projects of separation processes, thereby reducing capital and operating costs. Chitosanases are enzymes that hydrolyze the carbohydrate chitosan, resulting in oligosaccharides that have many remarkable biological activities, such as anti-cancer, anti-HIV and antioxidant activities. The two adsorbents had similar performance in relation to hydrodynamics and mass transfer. The results of the parametric sensitivity analysis agree with the literature, and the model was validated with an average high degree of fit (94.68%) between simulated and experimental data obtained in this work. 相似文献
82.
Raimundo A. Menezes Junior Angelo Vieira Mendonca 《机械工程与自动化:英文版》2014,(9):721-729
This work deals with the analysis of soil-structure interaction modeling of pipeline problems in static behavior using the coupling between FEM (finite element method) and BEM (boundary element method). The representation of the pipe is made by MEF using one fmite element in the cylindrical panel formulated from the theory of equivalent discrete layers (Layerwise theory), proposed by J. N. Reddy. The soil is represented by elastic continum infimite or semi-infinite and modeled using boundary elements with special curved surface, associated with cylindrical panel used to represent the soil-structure interaction within the soil, especially at the contact surface with the pipe. 相似文献
83.
Santiago Grijalvo Anna Clua Marc Eres Raimundo Gargallo Ramon Eritja 《International journal of molecular sciences》2021,22(1)
Two G-quadruplex forming oligonucleotides [d(TG4T)4 and d(TG6T)4] were selected as two tetramolecular quadruplex nanostructures because of their demonstrated ability to be modified with hydrophobic molecules. This allowed us to synthesize two series of G-quadruplex conjugates that differed in the number of G-tetrads, as well as in the terminal position of the lipid modification. Both solution and solid-phase syntheses were carried out to yield the corresponding lipid oligonucleotide conjugates modified at their 3′- and 5′-termini, respectively. Biophysical studies confirmed that the presence of saturated alkyl chains with different lengths did not affect the G-quadruplex integrity, but increased the stability. Next, the G-quadruplex domain was added to an 18-mer antisense oligonucleotide. Gene silencing studies confirmed the ability of such G-rich oligonucleotides to facilitate the inhibition of target Renilla luciferase without showing signs of toxicity in tumor cell lines. 相似文献
84.
Bruno da Cunha Diniz Raimundo Carlos Silverio Freire Junior Sandi Itamar Schafer de Souza 《机械工程与自动化:英文版》2014,(5):372-381
One of the main concerns in Engineering nowadays is the development of aircrafts of low consumption and high performance. For this purpose, airfoils are studied and designed to have an elevated lift coefficient and a low drag coefficient, thus generating a highly efficient airfoil. The higher the efficiency value is, the lower the aircraft fuel consumption will be; thus improving its performance. In this sense, this work aims to develop a tool for airfoil creation from some desired characteristics, such as the lift and drag coefficients and maximum efficiency rate, using an algorithm based on an ANN (artificial neural network). In order to do so, a database of aerodynamic characteristics with a total of 300 airfoils was initially collected from the XFoil software. Then, through a routine implemented in the MATLAB software, network architectures of one, two, three and four modules were trained, using the back propagation algorithm and momentum. The cross-validation technique was applied to analyze the results, evaluating which network possesses the lowest value in RMS (root-mean-square) error. In this case, the best result obtained was from the two-module architecture with two hidden neuron layers. The airfoils developed by this network, in the regions with the lowest RMS, were compared to the same airfoils imported to XFoil. The presented work offers as a contribution, in relation to other works involving ANN applied to fluid mechanics, the development of airfoils from their aerodynamic characteristics. 相似文献
85.
L. Gargallo N. Becerra C. Sandoval M. Pitsikalis N. Hadjichristidis A. Leiva D. Radic' 《应用聚合物科学杂志》2011,122(2):1395-1404
The behavior of amphiphilic diblock copolymers containing 80–89% of poly(N‐hexylisocyanate) (PHIC) with different hydrophobic segments spread at the air–water interface has been studied. Surface pressure‐area isotherms (π‐A) at the air–water interface were determined. It was found that these diblock copolymers form stable monolayers and the isotherms present a pseudoplateau region at low surface pressure, irrespective of the nature of the partner block: poly(styrene) (PS) or poly(isoprene). Surface pressure variation at the semidilute region of the monolayer was expressed in terms of the scaling laws as power function of the surface concentration. The critical exponents of the excluded volume ν obtained for copolymers with PHIC and PS blocks are 0.58 for the copolymer with 85% of PHIC and 15% of PS, and 0.63 for the copolymer with 89% of PHIC and 11% of PS. The hydrophobicity degree of the diblock copolymers was estimated from the determination of the surface energy values by wettability measurements. The morphology of the monolayers was determined by means of Brewster angle microscopy. Molecular dynamic simulation was performed to explain the experimental behavior of diblock copolymers at the air–water interface. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
86.
Ulisses M. Teles Fabiano A. N. Fernandes Sueli Rodrigues réa S. Lima Geraldo A. Maia & Raimundo W. Figueiredo 《International Journal of Food Science & Technology》2006,41(6):674-680
Osmotic dehydration represents a technological alternative to reduce post‐harvest losses of fruits. In this work, the influence of the osmotic solution concentration and osmotic solution to fruit weight ratio was examined on the osmotic dehydration of melons under vacuum. The process of osmotic dehydration followed by air‐drying was studied and modelled so that it could be optimised. The developed model has been validated with experimental data and simulations have shown that how the operating conditions affect the process. An optimisation was done using the model in order to search for the best operating condition that would reduce the total processing time. 相似文献
87.
Ada López Mariana G. da Silva Elisa Baggio-Saitovitch Alexandre R. Camara Raimundo N. SilveiraJr. Raul José Mauricio da Fonseca 《Journal of Materials Science》2008,43(2):464-468
Samples of SrAl2O4 and SrAl2O4:Cr3+ were prepared by mixing the powder materials SrCO3, Al2O3, and Cr2O3. The crystal structures of the undoped and doped samples were analyzed by X-ray diffraction (XRD) measurements. The diffraction
patterns reveal a dominant phase, characteristic of the monoclinic SrAl2O4 compound and another unknown secondary phase, in small amount, for doped samples. The data were fitted using the Rietveld
method for structural refinements and lattice parameter constants (a, b, c, and β) were determined. Luminescence of Cr3+ ions in this host is investigated for the first time by excitation and emission spectroscopy at room temperature. Emission
spectra present a larger band and a smaller structure associated to the
and electronic transitions, respectively. The obtained results are analyzed by crystal-field theory and the crystal-field parameter,
Dq, and Racah parameters, B and C, are determined from the excitation measurements. 相似文献
88.
C. Mendonça E. Freitas J.P. Ferreira I.D. Raimundo J.A. Santos 《Accident; analysis and prevention》2013
Road traffic sounds are a major source of noise pollution in urban areas. But recent developments such as low noise pavements and hybrid/electric engine vehicles cast an optimistic outlook over such an environmental problem. However, it can be argued that engine, tire, and road noise could be relevant sources of information to avoid road traffic conflicts and accidents. In this paper, we analyze the potential trade-offs of traffic-noise abatement approaches in an experimental study, focusing for the first time on the impact and interaction of relevant factors such as pavement type, vehicle type, listener's age, and background noise, on vehicle detection levels. Results reveal that vehicle and pavement type significantly affect vehicle detection. Age is a significant factor, as both younger and older people exhibit lower detection levels of incoming vehicles. Low noise pavements combined with all-electric and hybrid vehicles might pose a severe threat to the safety of vulnerable road users. All factors interact simultaneously, and vehicle detection is best predicted by the loudness signal-to-noise ratio. 相似文献
89.
90.
Raimundo Almeida-Filho Carolina M. Carvalho 《International journal of remote sensing》2013,34(4):1087-1094
Several areas of land degradation are present in the northeastern part of Brazil, resulting primarily from old practices of vegetation clearing and burning for subsistence farming and grazing. However, no reliable information is currently available on the extent of these areas and whether they are expanding over time. Taking the Gilbués region as an example, this study shows the potential for obtaining this information using multitemporal dual-season Landsat Thematic Mapper (TM) imagery. We used digital image processing, which involved the enhancement of soil-fraction images by segmentation/region classification and Normalized Difference Index (NDI) techniques. The results show highly degraded soils covering an almost continuous area of approximately 600 km2. The data also show that, over the past two decades, land degradation has been concentrated mainly along and in the heads of drainage systems, a pattern that indicates removal of riparian forests, thereby compounding the serious problem of sediment loading in the streams in the area. We show that satellite remotely sensed data can provide valuable information in support of environmental policies for northeast Brazil. 相似文献