219 research outputs found
A dynamic homogenization approach for modelling hybrid piezoelectric nanogenerators
No full textEnergy scavenging, from green and sustainable energy resources, is increasingly attracting the atten- tion of researchers and industries in several engineering fields. The main aim is capturing the energy, naturally available in the environment, and converting it into electrical energy. Emerging applica- tions, such as in flexible/strechable micro and nano electronics, biomedical monitoring, wearable technology, micro and nano robotics and extreme technology, require devices of smaller and smaller size and high performances
Il grano antico nella nutrizione umana: qualità nutrizionali di triticum monococcum e dicoccum
No full text[Abstract non disponibile
NURBS-Based Collocation Methods for the Structural Analysis of Shells of Revolution
No full textIn this work we present a collocation method for the structural analysis of shells of revolution based on Non-Uniform Rational B-Spline (NURBS) interpolation. The method is based on the strong formulation of the equilibrium equations according to Reissner-Mindlin theory, with Fourier series expansion of dependent variables, which makes the problem 1D. Several numerical tests validate convergence, accuracy, and robustness of the proposed methodology, and its feasibility as a tool for the analysis and design of complex shell structures
Expression of the H+-ATPase AHA10 proton pump is associated with citric acid accumulation in lemon juice sac cells.
No full textThe sour taste of lemons (Citrus limon (L.) Burm.) is determined by the amount of citric acid in vacuoles of juice sac cells. Faris is a “sweet”
lemon variety since it accumulates low levels of citric acid. The University of California Riverside Citrus Variety Collection includes a Faris tree that produces sweet (Faris non-acid; FNA) and sour fruit (Faris acid; FA) on different branches; it is apparently a graft chimera with layer L1 derived from Millsweet limetta and layer L2 from a standard lemon. The transcription profiles of Faris sweet lemon were compared with Faris acid lemon and Frost Lisbon (L), which is a standard sour lemon genetically indistinguishable from Faris in prior work with SSR markers.
Analysis of microarray data revealed that the transcriptomes of the two sour lemon genotypes were nearly identical. In contrast, the transcriptome of Faris sweet lemon was very different from those of both sour lemons.
Among about 1,000 FNAspecific, presumably pH-related genes, the homolog of Arabidopsis H+-ATPase proton pump AHA10 was not expressed in FNA, but highly expressed in FA and L. Since Arabidopsis AHA10 is involved in biosynthesis and acidification of vacuoles, the lack of expression of the AHA10 citrus homolog represents a very conspicuous molecular feature of the FNA sweet phenotype. In addition, high expression of several 2-oxoglutarate degradationrelated genes in FNA suggests activation of the GABA shunt and degradation of valine and tyrosine as components of the mechanism that reduces the level of citric acid in sweet lemon
Homogenization of Random Composite Materials: Sensitivity to Mechanical Parameters and Scaling Measures
No full textSeveral composite materials used in engineering, such as rocks, ceramic materials, concrete,
masonry-like materials, innovative meta-materials, have an internal micro-structure characterized
by a random distribution of inclusions embedded in a matrix. Mechanical properties of this type
of materials depend on the characteristics of the microstructure: mechanical properties of
components, geometrical shape and size of inclusions. The evaluation of effective mechanical
properties of this typology of materials is a topical issue.
A statistically-based homogenization procedure, previously developed by some of the authors
[1‐3], is adopted. This procedure allows us obtaining effective elastic properties of homogeneous
micro-polar continua able to naturally account for scale and skew–symmetric shear effects. The
so‐called Representative Volume Element (RVE) used to perform the homogenization procedure
is obtained by increasing a scale factor representing the ratio between the size of a control
window, referred as Statistical Volume Element (SVE), and the particle size until the statistical
convergence is reached.
In this work, in order to evaluate the effect of microstructure on the properties of such
materials, a series of parametric analyses are developed for two dimensional samples of
composites with disk-shaped inclusions. Two material cases are considered: inclusions stiffer or
softer than the matrix. Attention is paid to the phase contrast in elastic moduli (ratio between
inclusions and matrix moduli). The sensitivity of the effective material parameters to several
material contrast is investigated. Moreover, the convergence trend of properly defined
scaling‐measures is analyzed.
The results obtained for different kind of composites - ranging from metal or ceramic matrix
composites up to concrete, masonry-like and geo-materials - highlight the importance of taking
into account the spatial randomness of inclusions in identifying the bulk, shear and bending
behavior of composites as well as the effectiveness of the micro-polar continuum modeling.Several composite materials used in engineering, such as rocks, ceramic materials, concrete,
masonry-like materials, innovative meta-materials, have an internal micro-structure characterized
by a random distribution of inclusions embedded in a matrix. Mechanical properties of this type
of materials depend on the characteristics of the microstructure: mechanical properties of
components, geometrical shape and size of inclusions. The evaluation of effective mechanical
properties of this typology of materials is a topical issue.
A statistically-based homogenization procedure, previously developed by some of the authors
[1‐3], is adopted. This procedure allows us obtaining effective elastic properties of homogeneous
micro-polar continua able to naturally account for scale and skew–symmetric shear effects. The
so‐called Representative Volume Element (RVE) used to perform the homogenization procedure
is obtained by increasing a scale factor representing the ratio between the size of a control
window, referred as Statistical Volume Element (SVE), and the particle size until the statistical
convergence is reached.
In this work, in order to evaluate the effect of microstructure on the properties of such
materials, a series of parametric analyses are developed for two dimensional samples of
composites with disk-shaped inclusions. Two material cases are considered: inclusions stiffer or
softer than the matrix. Attention is paid to the phase contrast in elastic moduli (ratio between
inclusions and matrix moduli). The sensitivity of the effective material parameters to several
material contrast is investigated. Moreover, the convergence trend of properly defined
scaling‐measures is analyzed.
The results obtained for different kind of composites - ranging from metal or ceramic matrix
composites up to concrete, masonry-like and geo-materials - highlight the importance of taking
into account the spatial randomness of inclusions in identifying the bulk, shear and bending
behavior of composites as well as the effectiveness of the micro-polar continuum modeling
Intranasal nerve growth factor bypasses the blood-brain barrier and affects spinal cord neurons in spinal cord injury
No full textThe purpose of this work was to investigate whether, by intranasal administration, the nerve growth factor bypasses the blood-brain barrier and turns over the spinal cord neurons and if such therapeutic approach could be of value in the treatment of spinal cord injury. Adult Sprague-Dawley rats with intact and injured spinal cord received daily intranasal nerve growth factor administration in both nostrils for 1 day or for 3 consecutive weeks. We found an increased content of nerve growth factor and enhanced expression of nerve growth factor receptor in the spinal cord 24 hours after a single intranasal administration of nerve growth factor in healthy rats, while daily treatment for 3 weeks in a model of spinal cord injury improved the deficits in locomotor behaviour and increased spinal content of both nerve growth factor and nerve growth factor receptors. These outcomes suggest that the intranasal nerve growth factor bypasses blood-brain barrier and affects spinal cord neurons in spinal cord injury. They also suggest exploiting the possible therapeutic role of intranasally delivered nerve growth factor for the neuroprotection of damaged spinal nerve cells
Homogenization of Random Composite Materials: Sensitivity to Mechanical Parameters and Scaling Measures
No full textSeveral composite materials used in engineering, such as rocks, ceramic materials, concrete,
masonry-like materials, innovative meta-materials, have an internal micro-structure characterized
by a random distribution of inclusions embedded in a matrix. Mechanical properties of this type
of materials depend on the characteristics of the microstructure: mechanical properties of
components, geometrical shape and size of inclusions. The evaluation of effective mechanical
properties of this typology of materials is a topical issue.
A statistically-based homogenization procedure, previously developed by some of the authors
[1‐3], is adopted. This procedure allows us obtaining effective elastic properties of homogeneous
micro-polar continua able to naturally account for scale and skew–symmetric shear effects. The
so‐called Representative Volume Element (RVE) used to perform the homogenization procedure
is obtained by increasing a scale factor representing the ratio between the size of a control
window, referred as Statistical Volume Element (SVE), and the particle size until the statistical
convergence is reached.
In this work, in order to evaluate the effect of microstructure on the properties of such
materials, a series of parametric analyses are developed for two dimensional samples of
composites with disk-shaped inclusions. Two material cases are considered: inclusions stiffer or
softer than the matrix. Attention is paid to the phase contrast in elastic moduli (ratio between
inclusions and matrix moduli). The sensitivity of the effective material parameters to several
material contrast is investigated. Moreover, the convergence trend of properly defined
scaling‐measures is analyzed.
The results obtained for different kind of composites - ranging from metal or ceramic matrix
composites up to concrete, masonry-like and geo-materials - highlight the importance of taking
into account the spatial randomness of inclusions in identifying the bulk, shear and bending
behavior of composites as well as the effectiveness of the micro-polar continuum modeling
Efecto del producto Bellis (Pyraclostrobin y Boscalid) en la presencia de los patógenos post cosecha en el cultivo de pimiento Páprika en la provincia de Barranca
No full textUniversidad Nacional Agraria La Molina. Facultad de Agronomía. Departamento Académico de FitopatologíaMuchas de las enfermedades de poscosecha de frutos, hortalizas, granos y leguminosas son el resultado de infecciones incipientes de las plantas o sus frutos por patógenos que se encuentran ya en el campo. Los síntomas de dichas “infecciones de campo” pueden ser tan conspicuos que pueden pasar inadvertidos durante la cosecha. (Agrios, 1996). Penicillium y Aspergillus son considerados como los principales agentes causales de pudriciones post cosecha, produciendo mohos sobre los materiales vegetales y causando el deterioro de estos, algunas especies producen metabolitos secundarios que pueden ser tóxicos para el ser humano a los cuales se les conoce como micotoxinas. En el presente trabajo se evaluó el efecto del fungicida Bellis (pyraclostrobin y boscalid) en la presencia de patógenos post cosecha productores de micotoxinas en el cultivo de pimiento páprika. El ensayo se realizó en la localidad de Vinto Bajo, distrito y provincia de Barranca, departamento de Lima, la variedad de pimiento utilizada fue Papri King. Se evaluaron 6 tratamientos, la frecuencia de aplicación fue a los 40 días después de la siembra la primera, 15 días después de la primera aplicación la segunda y 15 días después de la segunda aplicación la tercera, los tratamientos evaluados fueron: T1, testigo absoluto sin aplicación; T2 tratamiento del agricultor, Bellis 0.8 kg/ha, Folicur (tebuconazole) 150ml/200L y Bayfidan (triadimenol) 150 ml/200L; T3, 2 aplicaciones de Bellis a la dosis de 0.6 kg/ha y Polyram (metiram) a la dosis de 2kg/ha; T4, 2 aplicaciones de Bellis a la dosis de 0.8 kg/ha y Polyram (metiram) a la dosis de 2kg/ha; T5, 3 aplicaciones de Bellis a la dosis de 0.6 kg/ha y T6, 3 aplicaciones de Bellis a la dosis de 0.8 kg/ha. El diseño estadístico fue de bloques completos al azar (DBCA) con 4 repeticiones constituido por parcelas de 21.6m2. El mejor tratamiento para evitar la presencia de Aspergillus y Penicillium fue el tratamiento 4, los frutos analizados en la cosecha como en la poscosecha no presentaron ninguno de estos patógenos. El tratamiento T3 (Bellis 0.6 Kg/ha x 3) constituyó el mejor tratamiento obteniendo diferencia con el testigo en los parámetros de; producción, Número de frutos buenos por planta; calidad, grados asta; económico, tratamiento no dominado, con una tasa de retorno marginal del T1 al T3 de 241%.Tesi
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