3,743 research outputs found
User's manual: Subsonic/supersonic advanced panel pilot code
Sufficient instructions for running the subsonic/supersonic advanced panel pilot code were developed. This software was developed as a vehicle for numerical experimentation and it should not be construed to represent a finished production program. The pilot code is based on a higher order panel method using linearly varying source and quadratically varying doublet distributions for computing both linearized supersonic and subsonic flow over arbitrary wings and bodies. This user's manual contains complete input and output descriptions. A brief description of the method is given as well as practical instructions for proper configurations modeling. Computed results are also included to demonstrate some of the capabilities of the pilot code. The computer program is written in FORTRAN IV for the SCOPE 3.4.4 operations system of the Ames CDC 7600 computer. The program uses overlay structure and thirteen disk files, and it requires approximately 132000 (Octal) central memory words
Antioxidant,antimicrobial and toxicological properties of Schinus molle L. essential oils
Ethnopharmacological relevance: Schinus molle L. has been used in folk medicine as antibacterial, antiviral, topical antiseptic, antifungal, antioxidant, anti-inflammatory, anti-tumoural as well as antispasmodic and analgesic; however, there are few studies of pharmacological and toxicological properties of S. molle essential oils.
Aim of the study: The aim of this study was to evaluate the antioxidant and antimicrobial activities of S. molle leaf and fruit essential oils, correlated with their chemical composition and evaluate their acute toxicity.
Materials and methods: The chemical composition of S. molle leaf and fruit essential oils were evaluated by GC-FID and GC-MS. Antioxidant properties were determined using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) free radical and β-carotene/linoleic acid methods. Antimicrobial properties were evaluated by the agar disc diffusion method and minimal inhibitory concentration assay. Toxicity in Artemia salina and acute toxicity with behavioural screening in mice were evaluated.
Results: The dominant compounds found in leaf and fruit essential oils (EOs) were monoterpene hydrocarbons, namely -phellandrene, β-phellandrene, β-myrcene, limonene and α-pinene. EOs showed low scavenging antioxidant activity by the DPPH free radical method and a higher activity by the β-carotene/linoleic acid method. Antimicrobial activity of EOs was observed for Gram+, Gram– pathogenic bacteria and food spoilage fungi. EOs showed cytotoxicity for Artemia salina and lower toxicity in Swiss mice.
Conclusions: The result showed that EOs of leaves and fruits of S. molle demonstrated antioxidant and antimicrobial properties, suggesting their potential use in food or pharmaceutical industries
CHEMICAL COMPOSITION, ANTIOXIDANT AND ANTIMICROBIAL PROPERTIES OF THREE ESSENTIAL OILS FROM PORTUGUESE FLORA
The present work reports on the evaluation of chemical composition and antioxidant and antimicrobial activities of essential oils of
three aromatic herbs, growing wild in the south of Portugal, used in traditional food preparations: Foeniculum vulgare, Mentha spicata and Rosmarinus officinalis. The principal components of essential oils were anethole (41.2%) for F. vulgare, carvone (41.1%) for M. spicata and myrcene (23.7%) for R. officinalis. Essential oils showed antioxidant activity either by DPPH radical scavenging method and system β-
carotene/acid linoleic method. Antimicrobial activity of essential oils was observed against pathogenic bacteria and yeasts and food spoilage fungi. F.vulgare essential oil showed bacterial activity against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa,
Salmonella enteritidis, Staphylococcus aureus, Aspergillus niger and Fusarium oxysporum with MICs of 0.25-0.75mg/mL. M. spicata oil was active against E.coli, S.aureus, C.albicans, A. niger and F. oxysporum with MICs ranging between 0.25 and 0.75mg/mL. R. officinalis essential oil showed activity against E.coli and C.albicans with MICs of 0.5-1.0mg/mL.
Having in account the important antioxidant and antimicrobial properties observed in present work, we consider that these essential oils might be useful on pharmaceutical and food industry as natural antibiotic and food preservativ
Force-induced misfolding in RNA
RNA folding is a kinetic process governed by the competition of a large
number of structures stabilized by the transient formation of base pairs that
may induce complex folding pathways and the formation of misfolded structures.
Despite of its importance in modern biophysics, the current understanding of
RNA folding kinetics is limited by the complex interplay between the weak
base-pair interactions that stabilize the native structure and the disordering
effect of thermal forces. The possibility of mechanically pulling individual
molecules offers a new perspective to understand the folding of nucleic acids.
Here we investigate the folding and misfolding mechanism in RNA secondary
structures pulled by mechanical forces. We introduce a model based on the
identification of the minimal set of structures that reproduce the patterns of
force-extension curves obtained in single molecule experiments. The model
requires only two fitting parameters: the attempt frequency at the level of
individual base pairs and a parameter associated to a free energy correction
that accounts for the configurational entropy of an exponentially large number
of neglected secondary structures. We apply the model to interpret results
recently obtained in pulling experiments in the three-helix junction S15 RNA
molecule (RNAS15). We show that RNAS15 undergoes force-induced misfolding where
force favors the formation of a stable non-native hairpin. The model reproduces
the pattern of unfolding and refolding force-extension curves, the distribution
of breakage forces and the misfolding probability obtained in the experiments.Comment: 28 pages, 11 figure
Unifying thermodynamic and kinetic descriptions of single-molecule processes: RNA unfolding under tension
We use mesoscopic non-equilibrium thermodynamics theory to describe RNA
unfolding under tension. The theory introduces reaction coordinates,
characterizing a continuum of states for each bond in the molecule. The
unfolding considered is so slow that one can assume local equilibrium in the
space of the reaction coordinates. In the quasi-stationary limit of high
sequential barriers, our theory yields the master equation of a recently
proposed sequential-step model. Non-linear switching kinetics is found between
open and closed states. Our theory unifies the thermodynamic and kinetic
descriptions and offers a systematic procedure to characterize the dynamics of
the unfolding processComment: 13 pages, 3 figure
Probing equilibrium glass flow up to exapoise viscosities
Glasses are out-of-equilibrium systems aging under the crystallization
threat. During ordinary glass formation, the atomic diffusion slows down
rendering its experimental investigation impractically long, to the extent that
a timescale divergence is taken for granted by many. We circumvent here these
limitations, taking advantage of a wide family of glasses rapidly obtained by
physical vapor deposition directly into the solid state, endowed with different
"ages" rivaling those reached by standard cooling and waiting for millennia.
Isothermally probing the mechanical response of each of these glasses, we infer
a correspondence with viscosity along the equilibrium line, up to exapoise
values. We find a dependence of the elastic modulus on the glass age, which,
traced back to temperature steepness index of the viscosity, tears down one of
the cornerstones of several glass transition theories: the dynamical
divergence. Critically, our results suggest that the conventional wisdom
picture of a glass ceasing to flow at finite temperature could be wrong.Comment: 4 figures and 1 supplementary figur
Kinematic analysis of a lower limb to determine the center of rotation of the knee at the sagittal plane.
En esta investigación se establece una metodologÃa que permite describir el movimiento de miembros inferiores
usando cadenas cinemáticas cerradas. Este análisis es realizado con el objetivo de determinar la posición del
centro de rotación (CR) de la rodilla localizado en el plano sagital. Un paciente sano y sin antecedentes patológicos
realizó pruebas de flexión-extensión con uno de sus miembros inferiores. Cuando el paciente realizo el movimiento
articular (la flexo-extensión) un dispositivo de video y un programa (World In motion v4.0) determinan la posición
de cuatro marcadores pasivos ubicados en el miembro inferior. Los datos obtenidos de los marcadores son utilizados
en un modelo propuesto que permite localizar la posición del CR de la rodilla. En este estudio se concluye que
el CR de la rodilla presenta movimiento relativo respecto a un punto fijo marcado en un miembro inferior. Los
resultados comprueban que el CR de la rodilla delimitado en el plano sagital no presenta comportamiento de una
junta completa (junta con un grado de libertad) como ha sido presentado en otros estudios. Abstract
A methodology is established in this research which permits to describe the movement of a lower limb using
closed kinematic chains. This analysis is developed with the aim to determine the location of the center of rotation
(CR) of the knee joint in the sagittal plane. Flexion-extension tests were carried out on one of the lower limbs of
a healthy patient without pathological antecedents. When the patient does articular movement (flexion-extension),
a video equipment and a software determine the position of four passive markers installed on the lower limb. The
information obtained from the markers is applied to the proposed model which allows to locate the center of rotation
of the knee joint. Hence it was concluded that the CR of the knee joint undergoes a relative movement with respect
to the fixed point marked on the lower limb. The results prove that the knee joint established in the sagittal plane
does not show the behavior of a complete joint (a joint with one degree of freedom) as it has been described in other
studies
Avaliação econômica de métodos alternativos para a colheita do guaraná.
Avaliacao dos metodos alternativos que permitem flexibilizar a epoca e o periodo da colheita do guarana (Paullinia cupana var. sorbilis), com monitoracao nas alteracoes no produto e no custo de producao decorrente dessa nova pratica. Foram definadas quatro modalidades de colheita: direta ou tradicional, indireta ou alternativa, mista - tipo 1 e mista - tipo 2. Os resultados indicaram que todas as combinacao dos metodos alternativos de colheita foram mais onerosas em relacao a tradicional. Porem, um aumento de 8,9% nos custos totais de producao indicam a viabilidade das alternativas, tendo em vista que elas podem porporcionar uma producao razoavel, em uma condicao onde poderia existir nenhuma, seja por escassez de mao-de-obra, seja por excesso de chuvas, podendo o produtor escolher entre os metodos alternativos aquele que mais lhe convier, em funcao de suas condicoes e caracteristicas proprias.bitstream/CPAA-2009-09/4462/1/IT_3_99.pd
Advanced tools and techniques to add value to soil stabilization practice
The aim of this paper is to demonstrate the advanced tools and techniques used for adding value to the soil stabilization practice. The tools presented involve advanced laboratory tests and modeling using codes and soft computing to evaluate the mechanical behavior of stabilized soils with cement, ranging from short-term to long-term behavior. More precisely, these tools are able to: 1. Predict the mechanical behavior of the stabilized soils over time from data obtained in the early ages saving time in laboratory tests; 2. Predict the mechanical behavior of the stabilized soils over time based on basic parameters of soil type and binder using historical accurate data, avoiding mechanical laboratory tests. 3. Incorporate the serviceability limit state concept in a novel proposal to estimate the design modulus in function of the uniaxial compressive strength and the strain level, making more economic and sustainable geotechnical solutions.This work was supported by FCT—‘‘Fundação para a Ciência e a Tecnologia’’, within ISISE, project UID/ECI/04029/2013 and through the post doctoral Grant fellowship with reference SFRH/BPD/94792/2013. This work was also partly financed by FEDER funds through the Competitivity Factors Operational Programme—COMPETE and by national funds through FCT within the scope of the project POCI-01-0145-FEDER-007633.info:eu-repo/semantics/publishedVersio
Production of thermoplastics matrix preimpregnated materials to manufacture composite pultruded profiles
The aim of this work is to optimize the production of new continuous carbon fibers reinforced polypropylene matrix pre-impregnated materials (towpregs) continuously processed by dry deposition of polypropylene (PP) powder by our own developed dry coating line. The processing of the produced towpregs by pultrusion, using a prototype equipment, was also optimized. The optimization of both processes was made by studying the influence of the most relevant processing parameters in the final properties of the produced towpregs and composites. The method of Taguchi/DOE (Design of Experiments) was used to allow the determination of the optimal processing windows. The possibility of using maleic anhydride as compatibilizer for polypropylene reinforced carbon fiber composites (CF/PP) was also analyzed. A pre-consolidate tape was produced by the melting cross-head extrusion process and its proprieties compared with those of towpregs. Finally, towpregs were characterized by scanning electron microscopy (SEM) and visual analysis. Their polymer mass contents were determined and the final pultruded composite profiles were also submitted to tensile, interlaminar, flexural, calcination and optical microscopy tests.Fundação para a Ciência e Tecnologia (FCT
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