Instituto Politécnico Nacional

About: Instituto Politécnico Nacional is a education organization based out in Mexico City, Mexico. It is known for research contribution in the topics: Population & Context (language use). The organization has 43351 authors who have published 63315 publications receiving 938532 citations. The organization is also known as: Instituto Politécnico Nacional & Instituto Politecnico Nacional.

The Transport of Nanoparticles in Blood Vessels: The Effect of Vessel Permeability and Blood Rheology

Abstract: The longitudinal transport of nanoparticles in blood vessels has been analyzed with blood described as a Casson fluid. Starting from the celebrated Taylor and Aris theory, an explicit expression has been derived for the effective longitudinal diffusion (D eff) depending non-linearly on the rheological parameter ξc, the ratio between the plug and the vessel radii; and on the permeability parameters $$\Uppi$$ and $$\Upomega ,$$ related to the hydraulic conductivity and pressure drop across the vessel wall, respectively. An increase of ξc or $$\Uppi$$ has the effect of reducing D eff, and thus both the rheology of blood and the permeability of the vessels may constitute a physiological barrier to the intravascular delivery of nanoparticles.

Gold nanoparticles as efficient antimicrobial agents for Escherichia coli and Salmonella typhi

Abstract: It is imperative to eliminate bacteria present in water in order to avoid problems in healthy. Escherichia coli and Salmonella typhi bacteria are two common pollutants and they are developing resistance to some of the most used bactericide. Therefore new biocide materials are being tested. Thus, gold nanoparticles are proposed to inhibit the growth of these two microorganisms. Gold nanoparticles were supported onto clinoptilolite, mordenite and faujasite zeolites. Content of gold in materials varied between 2.3 and 2.8 wt%. The size, dispersion and roughness of gold nanoparticles were highly dependent of the zeolite support. The faujasite support was the support where the 5 nm nanoparticles were highly dispersed. The efficiency of gold-zeolites as bactericides of Escherichia coli and Salmonella typhi was determined by the zeolite support. Gold nanoparticles dispersed on zeolites eliminate Escherichia coli and Salmonella typhi at short times. The biocidal properties of gold nanoparticles are influenced by the type of support which, indeed, drives key parameters as the size and roughness of nanoparticles. The more actives materials were pointed out Au-faujasite. These materials contained particles sized 5 nm at surface and eliminate 90–95% of Escherichia coli and Salmonella typhi colonies.

Confinement-shear lattice model for concrete damage in tension and compression: ii. computation and validation

Abstract: The concrete material model developed in the preceding Part I of this study is formulated numerically. The new model is then verified by comparisons with experimental data for compressive and tensile uniaxial tests, biaxial tests, and triaxial tests, as well as notched tests of mode I fracture and size effect.

Sugar and ABA responsiveness of a minimal RBCS light‐responsive unit is mediated by direct binding of ABI4

Abstract: *Summary Photosynthesis-associated nuclear genes (PhANGs) are able to respond to multiple environmental and developmental signals, including light, sugars and abscisic acid (ABA). PhANGs have been extensively studied at the level of transcriptional regulation and several cis-acting elements important for light responsiveness have been identified in their promoter sequences. However, the regulatory elements involved in sugar and ABA regulation of PhANGs have not been completely characterized. Using conserved modular arrangement 5 (CMA5), a previously characterized minimal light-responsive unit, we show that in Arabidopsis thaliana this unit responds not only positively to light signals, but also negatively to sugars and ABA. The latter responses were found to be impaired in the abi4 mutant, indicating that ABSCISIC ACID INSENSITIVE-4 (ABI4) is a regulator involved in sugar and ABA repression of this minimal regulatory unit. Furthermore, we report a new sequence element conserved in several rbcS promoters, herewith named S-box, which is important for the sugar and ABA responsiveness of CMA5. This sequence corresponds to a putative ABI4-binding site, which is in fact bound by the Arabidopsis ABI4 protein in vitro. The S-box is closely associated with the G-box present in CMA5, and this association is conserved in the promoters of several RBCS genes. This phylogenetically conserved promoter feature probably reflects a common regulatory mechanism and identifies a point of convergence between light- and sugar-signaling pathways.

Molecular biology of capsaicinoid biosynthesis in chili pepper (Capsicum spp.)

Abstract: Capsicum species produce fruits that synthesize and accumulate unique hot compounds known as capsaicinoids in placental tissues The capsaicinoid biosynthetic pathway has been established, but the enzymes and genes participating in this process have not been extensively studied or characterized Capsaicinoids are synthesized through the convergence of two biosynthetic pathways: the phenylpropanoid and the branched-chain fatty acid pathways, which provide the precursors phenylalanine, and valine or leucine, respectively Capsaicinoid biosynthesis and accumulation is a genetically determined trait in chili pepper fruits as different cultivars or genotypes exhibit differences in pungency; furthermore, this characteristic is also developmentally and environmentally regulated The establishment of cDNA libraries and comparative gene expression studies in pungent and non-pungent chili pepper fruits has identified candidate genes possibly involved in capsaicinoid biosynthesis Genetic and molecular approaches have also contributed to the knowledge of this biosynthetic pathway; however, more studies are necessary for a better understanding of the regulatory process that accounts for different accumulation levels of capsaicinoids in chili pepper fruits