Aminopyrazoles and their conjugated acids. An X-ray study of 3,5-dimethyl-4-aminopyrazole and the Picrate of 3(5)-aminopyrazole

The crystal structure determination of 3,5-dimethyl-4-aminopyrazole ( 3 ) and of 3(5)-aminopyrazolium picrate salt ( 5a ) have been undertaken. The packing in 3 is characterized by the formation of sheets in which the N-H of the pyrazole and one H atom of the amino group are involved. The remaining HB donor interconnects sheets. In 5a , the anions and the cations are linked by a two-dimensional network of hydrogen bonds in the ab plane. Each N-H and C-H in the cation are involved in hydrogen interactions with the O atoms of the anion. Ab initio molecular orbital methods at the HF and B3LYP levels using a 6–31G** basis set have been carried out to compare the relative stability of the tautomeric forms of the 3(5)-aminopyrazolium and 4-aminopyrazolium cations.     

Changes in the vascular tissue of fresh Hass avocados treated with cobalt 60

This research was based on fresh avocado fruit treated with gamma rays at quarantine doses and stored at room temperature. The effects of irradiation were analyzed and measured by three different types of studies: histological, biochemical and physiological. Histological studies were focused on the effect of Cobalt 60 gamma rays in the mesocarp of avocado irradiated at three different doses; 150, 250, and 350 Gy. Damage was observed principally in the parenchyma tissue where the cell membrane was plazmolized and a red color was observed due to the development of phenol compounds. Another important effect was an increase in the size of xylem and phloem cells in the vascular tissue even at the minimum dose of 150 Gy. The biochemical and the physiological studies were done on avocado fruit irradiated at 100 and 150 Gy. An increase in L-phenilalanine ammonialyase activity was observed and therefore, an increase in the concentration of phenol compounds. These changes were not perceived by panelists in a sensorial test. Irradiated fruits were accepted by panelists as well as control fruit as regards parameters of taste, internal color and external color. These results demonstrate the feasibility of using irradiation to disinfest avocado fruit using a minimum dose of 100 Gy.     

Specific peptides as alternative to antibody ligands for biomagnetic separation of Clostridium tyrobutyricum spores

Nowadays, the reference method for the detection of Clostridium tyrobutyricum in milk is the most-probable-number method, a very time-consuming and non-specific method. In this work, the suitability of the use of superparamagnetic beads coated with specific antibodies and peptides for bioseparation and concentration of spores of C. tyrobutyricum has been assessed. Peptide or antibody functionalized nanoparticles were able to specifically bind C. tyrobutyricum spores and concentrate them up to detectable levels. Moreover, several factors, such as particle size (200 nm and 1 μm), particle derivatization (aminated and carboxylated beads), coating method, and type of ligand have been studied in order to establish the most appropriate conditions for spore separation. Results show that concentration of spore is favored by a smaller bead size due to the wider surface of interaction in relation to particle volume. Antibody orientation, related to the binding method, is also critical in spore recovery. However, specific peptides seem to be a better ligand than antibodies, not only due to the higher recovery ratio of spores obtained but also due to the prolonged stability over time, allowing an optimal recovery of spores up to 3 weeks after bead coating. These results demonstrate that specific peptides bound to magnetic nanoparticles can be used instead of traditional antibodies to specifically bind C. tyrobutyricum spores being a potential basis for a rapid method to detect this bacterial target.     

Mutagenicity of flavonoids assayed by bacterial reverse mutation (Ames) test

The mutagenicity of ten flavonoids was assayed by the Ames test, in Salmonella typhimurium strains TA98, TA100 and TA102, with the aim of establishing hydroxylation pattern-mutagenicity relationship profiles. The compounds assessed were: quercetin, kaempferol, luteolin, fisetin, chrysin, galangin, flavone, 3-hydroxyflavone, 5-hydroxyflavone and 7-hydroxyflavone. In the Ames assay, quercetin acted directly and its mutagenicity increased with metabolic activation. In the presence of S9 mix, kaempferol and galangin were mutagenic in the TA98 strain and kaempferol showed signs of mutagenicity in the other strains. The absence of hydroxyl groups, as in flavone, only signs of mutagenicity were shown in strain TA102, after metabolization and, among monohydroxylated flavones (3-hydroxyflavone, 5-hydroxyflavone and 7-hydroxyflavone), the presence of hydroxyl groups only resulted in minor changes. Luteolin and fisetin also showed signs of mutagenicity in strain TA102. Finally, chrysin, which has only two hydroxy groups, at the 5-OH and 7-OH positions, also did not induce mutagenic activity in any of the bacterial strains used, under either activation condition. All the flavonoids were tested at concentrations varying from 2.6 to 30.7 nmol/plate for galangin and 12.1 to 225.0 nmol/plate for other flavonoids. In light of the above, it is necessary to clarify the conditions and the mechanisms that mediate the biological effects of flavonoids before treating them as therapeutical agents, since some compounds can be biotransformed into more genotoxic products; as is the case for galangin, kaempferol and quercetin.     

CaSO4 and its pressure-induced phase transitions. A density functional theory study

Theoretical investigations concerning possible calcium sulfate, CaSO(4), high-pressure polymorphs have been carried out. Total-energy calculations and geometry optimizations have been performed by using density functional theory at the B3LYP level for all crystal structures considered. The following sequence of pressure-driven structural transitions has been found: anhydrite, Cmcm (in parentheses the transition pressure) → monazite-type, P2(1)/n (5 GPa) → barite-type, Pnma (8 GPa), and scheelite-type, I4(1)/a (8 GPa). The equation of state of the different polymorphs is determined, while their corresponding vibrational properties have been calculated and compared with previous theoretical results and experimental data.     

New spaces of functions and hyperfunctions for Hankel transforms and convolutions

In this paper we study the Hankel transformation and convolution on certain spaces of entire functions and its dual that is a space of hyperfunctions and contains the (even)-Schwartz space S _e ′. We prove that the Hankel transform is an automorphism of . Also the Hankel convolutors of are investigated. Authors’ addresses: Jorge J. Betancor, Claudio Jerez and Lourdes Rodríguez-Mesa, Departamento de Análisis Matemático, Universidad de la Laguna, Campus de Anchieta, Avda. Astrofísico Francisco Sánchez, s/n, 38271 La Laguna (Sta. Cruz de Tenerife), Espa?a; Sandra M. Molina, Departamento de Matemáticas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350 (7600), Mar del Plata, Argentina     

Pure Picard-Vessiot extensions with generic properties

Given a connected linear algebraic group over an algebraically closed field of characteristic 0, we construct a pure Picard-Vessiot extension for , namely, a Picard-Vessiot extension , with differential Galois group , such that and are purely differentially transcendental over . The differential field is the quotient field of a -stable proper differential subring with the property that if is any differential field with field of constants and is a Picard-Vessiot extension with differential Galois group a connected subgroup of , then there is a differential homomorphism such that is generated over as a differential field by .

     

Variation Operators for Semigroups and Riesz Transforms on BMO in the Schrödinger Setting

In this paper we prove that the variation operators of the heat semigroup and the truncations of Riesz transforms associated to the Schrödinger operator are bounded on a suitable BMO type space.