Averaged Scale in Electronegativity Joined to Physicochemical Perturbations. Consequences of Periodicity.

In this work, we propose a new representative electronegativity scale χ based on a statistical analysis of 11 electronegativity scales associated with electric ionic resonance energy, ionization potential, electron affinity, polarizability, electric force, average orbital energy, chemical potential, electrochemical reduction potential, and electric potential energy. Among these scales, it is the new PE° electronegativity scale, which relates the reduction potential ° to Pauling's electronegativity scale. The scale χ gives more weight to the physicochemical factors, which influence the electronegativity, but this scale is not necessarily the best electronegativity scale for the element.

Relationship between the Atomic Structure and Electrochemistry. 1. Electric Force, Standard Reduction Potential °, and Standard Reaction Gibbs Free Energy Δ°.

The relationship among the standard reaction Gibbs free energy Δ°, the standard reduction potential °, and the atomic structure parameters of radius, nuclear charge, and isoelectronic orbitals l is accomplished through the attraction electric force . In relationship with °, it was necessary to define two new reference scales: with a final state of ° in the element, which allowed to have a parabolic trend of Δ° versus , and whose final state is the ion with a more negative charge (e.g.

Enzymatic Activity of Glutathione S-Transferase and Dental Fluorosis Among Children Receiving Two Different Levels of Naturally Fluoridated Water.

This study was conducted to measure the activity of the enzyme glutathione S-transferase (GST) in saliva and to compare the activity of this enzyme in children with and without dental fluorosis in communities with different concentrations of naturally fluoridated water. A total of 141 schoolchildren participated in this cross-sectional study. Children were selected from two communities: one with a low (0.

Comparative Study of the Optical and Textural Properties of Tetrapyrrole Macrocycles Trapped Within ZrO₂, TiO₂, and SiO₂ Translucent Xerogels.

The entrapping of physicochemical active molecules inside mesoporous networks is an appealing field of research due to the myriad of potential applications in optics, photocatalysis, chemical sensing, and medicine. One of the most important reasons for this success is the possibility of optimizing the properties that a free active species displays in solution but now trapped inside a solid substrate. Additionally it is possible to modulate the textural characteristics of substrates, such as pore size, specific surface area, polarity and chemical affinity of the surface, toward the physical or chemical adhesion of a variety of adsorbates.

Using the M13 Phage as a Biotemplate to Create Mesoporous Structures Decorated with Gold and Platinum Nanoparticles.

By taking advantage of the physical and chemical properties of the M13 bacteriophage, we have used this virus to synthesize mesoporous silica structures. Major coat protein p8 was chemically modified by attaching thiol groups. As we show, the resulting thiolated phage can be used as a biotemplate able to direct the formation of mesoporous silica materials.

The π-back-bonding modulation and its impact in the electronic properties of Cu(II) antineoplastic compounds: an experimental and theoretical study.

A complete study of the electronic density distribution in antineoplastic mixed chelate complexes of the type [Cu(N-N)(glycinate)H2 O]NO3 (N-N=2,2'-bipyridine (bpy) (1), 4,4'-dimethyl-bpy (2), 5,5'-dimethyl-2,2'-bipyridine (3), 1,10-phenanthroline (phen) (4), 4-methyl-phen (5); 5-methyl-phen (6); 4,7-dimethyl-phen (7), 5,6-dimethyl-phen (8), and 3,4,7,8-tetramethyl-phen (9)), a family known as Casiopeínas, was carried out with cyclic voltammetry, EPR, and computational methods. Crystal structures of 1⋅H2 O, 2⋅H2 O, 3⋅H2 O, 6⋅H2 O, and 8⋅H2 O show the variability in the geometries adopted by the copper compounds in the solid state. Experimental properties are described employing electronic descriptors obtained from computational methods.

Biomimetic sol-gel synthesis of TiO₂ and SiO₂ nanostructures.

We report the heptapeptide-mediated biomineralization of titanium dioxide nanoparticles from titanium alkoxides. We evaluated the influence of pH on the biomineralized products and found that nanostructured TiO2 was formed in the absence of external ions (water only) at pH ~ 6.5.

Crossed and linked histories of tetrapyrrolic macrocycles and their use for engineering pores within sol-gel matrices.

The crossed and linked histories of tetrapyrrolic macrocycles, interwoven with new research discoveries, suggest that Nature has found in these structures a way to ensure the continuity of life. For diverse applications porphyrins or phthalocyanines must be trapped inside solid networks, but due to their nature, these compounds cannot be introduced by thermal diffusion; the sol-gel method makes possible this insertion through a soft chemical process. The methodologies for trapping or bonding macrocycles inside pristine or organo-modified silica or inside ZrO₂ xerogels were developed by using phthalocyanines and porphyrins as molecular probes.

Surfactantless synthesis and textural properties of self-assembled mesoporous SnO(2).

Ordered surfactantless self-assembled, mesoporous SnO(2) adsorbents, consisting of tubular voids of nanometric sizes, are prepared by the sol-gel processing of tin (IV) tetra-tert-amyloxide, Sn(OAm(t))(4), whose molecules have been previously chelated with acetylacetone in the absence of water, to modulate their reactivity and to promote an incipient self-assembling of -O-Sn-O oligomeric species; ultimately, the necessary amount of water to induce the hydrolysis-condensation reactions is added to this aged sol, then producing tubular pore templates within the SnO(2) xerogel network. A collection of mesoporous SnO(2) xerogels of assorted structural properties has been obtained after calcination in air of precursory gels proceeding from an aged mixture of Sn(OAm(t))(4) and acetylacetone at temperatures in the range 200-1000 degrees C. N(2) sorption isotherms measured on these SnO(2) solids evidence mesoporous structures of diverse textural characteristics (i.

Physicochemical aspects of novel surfactantless, self-templated mesoporous SnO2 thin films.

A novel method of synthesis consisting of the production of ordered arrangements of tubular pores distributed inside SnO2 annealed thin films, which are prepared from a rotating disk process carried out at 2000-3500 rpm, is herein described. The main novelty is that no surfactant molecules are required in order to create these ordered pore structures; the templating entities are supramolecular assemblies of oligomeric chains formed during the extra-long aging allowed to the sol-gel processing of tin(IV) tetra-tert-amiloxide, Sn(OAm(t))4, chelated with acetylacetone molecules. Low angle X-ray diffraction peaks of SnO2 thin films calcined at 500 degrees C clearly certify the existence of ordered mesostructures when employing the right H2O/Sn(OAm(t))4 molar ratio during the SnO2 sol-gel synthesis.