Nitrogen-containing carbon nanotubes

Carbon nanotubes containing small amounts of nitrogen are produced by the pyrolysis of aza-aromatics such as pyridine, methylpyrimidine and triazine over cobalt nanoparticles in an Ar atmosphere; good yields of such nanotubes are obtained by carrying out the pyrolysis of a mixture of pyridine and Fe(CO)(5) in flowing Ar + H-2.

C-H functionalization of tertiary amines by cross dehydrogenative coupling reactions: solvent-free synthesis of alpha-aminonitriles and beta-nitroamines under aerobic condition

A solvent-free synthesis of alpha-aminonitriles and beta-nitroamines by oxidative cross-dehydrogenative coupling under aerobic condition is reported. A catalytic amount of molybdenum(VI) acetylacetonoate was found to catalyze cyanation of tertiary amines to form alpha-aminonitriles, whereas vanadium pentoxide was found to promote aza-Henry reaction to furnish beta-nitroamines. Both of these environmentally benign reactions are performed in the absence of solvents using molecular oxygen as an oxidant.

Tetraethylammonium Tetraselenotungstate: A Versatile Selenium Transfer Reagent in Organic Synthesis

Organoselenium compounds have attracted intense research owing to their unique biological properties as well as pharmaceutical significance. Progress has been made in developing reagents for incorporation of selenium in an efficient and controlled manner. Herein, we present a review on the recently developed selenium reagent, tetraethylammonium tetraselenotungstate, Et4N](2)WSe4 as a versatile selenium transfer reagent in organic synthesis. Tetraselenotungstate has been successfully used for the synthesis of a number of functionalized diselenides, sugar- and nucleoside-derived diselenides, seleno-cystines, selenohomocystines, selenoamides, selenoureas and sugar- and nucleoside-based cyclic-selenide derivatives. Additionally, this reagent has been employed for the ring opening of aziridines to synthesize a variety of beta-aminodiselenides. A new selena-aza-Payne type rearrangement of aziridinemethanoltosylates mediated by tetraselenotungstate for the synthesis of allyl amines is also discussed.

Linear and nonlinear optical properties of expanded porphyrins: a DMRG study

We study absorption spectra and two photon absorption coefficient of expanded porphyrins (EPs) by the density matrix renormalization group (DMRG) technique. We employ the Pariser-Parr-Pople (PPP) Hamiltonian which includes long-range electron-electron interactions. We find that, in the 4n+2 EPs, there are two prominent low-lying one-photon excitations, while in 4n EPs, there is only one such excitation. We also find that 4n+2 EPs have large two-photon absorption cross sections compared to 4n EPs. The charge density rearrangement in the one-photon excited state is mostly at the pyrrole nitrogen site and at the meso carbon sites. In the two-photon states, the charge density rearrangement occurs mostly at the aza-ring sites. In the one-photon state, the C-C bond length in aza rings shows a tendency to become uniform. In the two-photon state, the bond distortions are on C-N bonds of the pyrrole ring and the adjoining C-C bonds which connect the pyrrole ring to the aza or meso carbon sites.

Change in Mesoherbivore Browsing Is Mediated by Elephant and Hillslope Position

Elephant are considered major drivers of ecosystems, but their effects within small-scale landscape features and on other herbivores still remain unclear. Elephant impact on vegetation has been widely studied in areas where elephant have been present for many years. We therefore examined the combined effect of short-term elephant presence (< 4 years) and hillslope position on tree species assemblages, resource availability, browsing intensity and soil properties. Short-term elephant presence did not affect woody species assemblages, but did affect height distribution, with greater sapling densities in elephant access areas. Overall tree and stem densities were also not affected by elephant. By contrast, slope position affected woody species assemblages, but not height distributions and densities. Variation in species assemblages was statistically best explained by levels of total cations, Zinc, sand and clay. Although elephant and mesoherbivore browsing intensities were unaffected by slope position, we found lower mesoherbivore browsing intensity on crests with high elephant browsing intensity. Thus, elephant appear to indirectly facilitate the survival of saplings, via the displacement of mesoherbivores, providing a window of opportunity for saplings to grow into taller trees. In the short-term, effects of elephant can be minor and in the opposite direction of expectation. In addition, such behavioural displacement promotes recruitment of saplings into larger height classes. The interaction between slope position and elephant effect found here is in contrast with other studies, and illustrates the importance of examining ecosystem complexity as a function of variation in species presence and topography. The absence of a direct effect of elephant on vegetation, but the presence of an effect on mesoherbivore browsing, is relevant for conservation areas especially where both herbivore groups are actively managed.

Teología, 1975, Tomo XII nº 025-026 (número completo)

La Iglesia y la existencia cristiana / José Rovai -- Avaricia, propiedad privada y bienes superfluos / Gustavo E. Podestá -- Teología natural y teología cristiana / Ricardo Ferrara -- Evangelización, cultura, universidad / Eduardo Briancesco -- En torno a la cristología de Marcos / Ramón Treviajno Echeverría -- La evangelización del mundo de hoy en América Latina / Eduardo F. Pironio -- La Biblia y la teología, hoy / Jorge Mejía -- Algunas reflexiones sobre la exhortación apostólica del Papa Pablo VI: “De Beatae Mariae Virginis cultu recte instituendo et augendo” / Heriberto King -- Evangelizar desde el acontecimiento / Arturo Prins -- Notas bibliográficas -- Libros recibidos -- Crónica de la Facultad

La deshumanización en la atención profesional : ¿vulnera el derecho a la intimidad?

Resumen: El problema de la deshumanización de la atención médica sido enfocado desde ópticas diferentes (y en diversos momentos históricos), ya sea desde la perspectiva del paciente, de los familiares o del propio equipo de salud que presta los servicios, pero no hay un estudio de las causas y de las posibles soluciones. Al realizar un recorrido de la atención profesional en el mundo de la salud observamos que solo podemos re humanizar esa atención con el compromiso directo de todos los participantes del equipo de salud para promover actos y condiciones que tengan como finalidad el respeto de los derechos humanos que se afirman en la dignidad de cada persona enferma. Creemos que esta presentación puede llevar a tomar conciencia sobre la vulnerabilidad de la intimidad en el proceso, hoy deshumanizante, de la atención profesional en el ámbito de la salud y desde este punto de partida asumiendo las responsabilidades subjetivas, sin anular la moralidad objetiva del hecho, comprometiéndonos a denunciar estas situaciones injustas y a trabajar día a día para humanizar la atención y de esta forma respetar el derecho a la intimidad.

Plasma brain-derived neurotrophic factor levels, learning capacity and cognition in patients with first episode psychosis

Background: Cognitive impairments are seen in first psychotic episode (FEP) patients. The neurobiological underpinnings that might underlie these changes remain unknown. The aim of this study is to investigate whether Brain Derived Neurotrophic Factor (BDNF) levels are associated with cognitive impairment in FEP patients compared with healthy controls. Methods: 45 FEP patients and 45 healthy controls matched by age, gender and educational level were selected from the Basque Country area of Spain. Plasma BDNF levels were assessed in healthy controls and in patients. A battery of cognitive tests was applied to both groups, with the patients being assessed at 6 months after the acute episode and only in those with a clinical response to treatment. Results: Plasma BDNF levels were altered in patients compared with the control group. In FEP patients, we observed a positive association between BDNF levels at six months and five cognitive domains (learning ability,immediate and delayed memory, abstract thinking and processing speed) which persisted after controlling for medications prescribed, drug use, intelligence quotient (IQ) and negative symptoms. In the healthy control group, BDNF levels were not associated with cognitive test scores. Conclusion: Our results suggest that BDNF is associated with the cognitive impairment seen after a FEP. Further investigations of the role of this neurotrophin in the symptoms associated with psychosis onset are warranted.

Ekialdeko Kantauriar itsasoko kostaldeko bakterioen isolamendua eta kontserbazioa

Ekialdeko Kantauriar itsasoko kostaldeko bakterioen isolamendua eta kontserbazioa

Implementación de algoritmos de Inteligencia Swarm con fines didácticos

Con este proyecto hemos querido proporcionar un conjunto de recursos útiles para la impartición de un curso de Swarm Intelligence enfocado a la Particle Swarm Optimization (PSO). Estos recursos constan de una aplicación en NetLogo para poder experimentar, ejecutar y visualizar los diferentes modelos de la PSO, un review de la Swarm Intelligence profundizando en la PSO y una ontología de PSO que incluye los recursos bibliográficos necesarios para la investigación y la escritura de artículos.

Hydrazides and hydrazones as versatile Michael-Donors for iminium-catalyzed conjugate addition reactions

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Cannabis use and involuntary admission may mediate long-term adherence in first-episode psychosis patients: a prospective longitudinal study

Background: This study aimed to examine factors associated with treatment adherence in first-episode psychosis (FEP) patients followed up over 8 years, especially involuntary first admission and stopping cannabis use. Methods: This prospective, longitudinal study of FEP patients collected data on symptoms, adherence, functioning,and substance use. Adherence to treatment was the main outcome variable and was categorized as ‘good’ or ‘bad’. Cannabis use during follow-up was stratified as continued use, stopped use, and never used. Bivariate and logistic regression models identified factors significantly associated with adherence and changes in adherence over the 8-year follow-up period. Results: Of the 98 FEP patients analyzed at baseline, 57.1% had involuntary first admission, 74.4% bad adherence,and 52% cannabis use. Good adherence at baseline was associated with Global Assessment of Functioning score (p = 0.019), Hamilton Depression Rating Scale score (p = 0.017) and voluntary admission (p < 0.001). Adherence patterns over 8 years included: 43.4% patients always bad, 26.1% always good, 25% improved from bad to good. Among the improved adherence group, 95.7% had involuntary first admission and 38.9% stopped cannabis use. In the subgroup of patients with bad adherence at baseline, involuntary first admission and quitting cannabis use during follow up were associated with improved adherence. Conclusions: The long-term association between treatment adherence and type of first admission and cannabis use in FEP patients suggest targets for intervention to improve clinical outcomes.

Binding site size limitations of imidazole-pyrrole polyamides for recognition in the minor groove of DNA

The discovery that the three ring polyamide Im-Py-Py-Dp containing imidazole (Im) and pyrrole (Py) carboxamides binds the DNA sequence 5'-(A,T)G(A,T)C(A,T)-3' as an antiparallel dimer offers a new model for the design of ligands for specific recognition of sequences in the minor groove containing both G,C and A,T base pairs. In Chapter 2, experiments are described in which the sequential addition of five N- methylpyrrolecarboxamides to the imidazole-pyrrole polyamide Im-Py-Py-Dp affords a series of six homologous polyamides, Im-(Py)_2-7-Dp, that differ in the size of their binding site, apparent first order binding affinity, and sequence specificity. These results demonstrate that DNA sequences up to nine base pairs in length can be specifically recognized by imidazole-pyrrole polyamides containing three to seven rings by 2:1 polyamide-DNA complex formation in the minor groove. Recognition of a nine base pair site defines the new lower limit of the binding site size that can be recognized by polyamides containing exclusively imidazole and pyrrolecarboxamides. The results of this study should provide useful guidelines for the design of new polyamides that bind longer DNA sites with enhanced affinity and specificity.

In Chapter 3 the design and synthesis of the hairpin polyamide Im-Py-Im-Py-γ-Im- Py-Im-Py-Dp is described. Quantitative DNase I footprint titration experiments reveal that Im-Py-Im-Py-γ-Im-Py-Im-Py-Dp binds six base pair 5'-(A,T)GCGC(A,T)-3' sequences with 30-fold higher affinity than the unlinked polyamide Im-Py-Im-Py-Dp. The hairpin polyamide does not discriminate between A•T and T•A at the first and sixth positions of the binding site as three sites 5'-TGCGCT-3', 5'-TGCGCA-3', and 5 'AGCGCT- 3' are bound with similar affinity. However, Im-Py-Im-Py-γ-Im-Py-Im-PyDp is specific for and discriminates between G•C and C•G base pairs in the 5'-GCGC-3' core as evidenced by lower affinities for the mismatched sites 5'-AACGCA-3', 5'- TGCGTT-3', 5'-TGCGGT-3', and 5'-ACCGCT-3'.

In Chapter 4, experiments are described in which a kinetically stable hexa-aza Schiff base La³⁺ complex is covalently attached to a Tat(49-72) peptide which has been shown to bind the HIV-1 TAR RNA sequence. Although these metallo-peptides cleave TAR site-specifically in the hexanucleotide loop to afford products consistent with hydrolysis, a series of control experiments suggests that the observed cleavage is not caused by a sequence-specifically bound Tat(49-72)-La(L)³⁺ peptide.

Development of Asymmetric Protonation Reactions for the Synthesis of Indoline Alkaloids

Nitrogen-containing heterocycles, such as indolines and pyrroloindolines, are prevalent in a variety of diverse natural products, many of which exhibit remarkable biological activities. These frameworks have inspired innovative research aimed at discovering novel methods for their stereoselective preparation.

We have developed an enantioselective synthesis of pyrroloindolines based on a formal (3 + 2) cycloaddition of indoles and 2-amidoacrylates. This reaction is promoted by (R)-BINOL•SnCl₄; this complex is a Lewis acid-assisted Brønsted acid that effects a highly face-selective catalyst-controlled protonation of an enolate. Mechanistic studies also determined that the initial product of this reaction is an indolinium ion, which upon aqueous workup undergoes cyclization to the pyrroloindoline.

Based on this result, we investigated alternative nucleophiles to trap the indolinium ion. First, addition of sodium borohydride to the optimized reaction conditions yields indoline-containing amino acid derivatives.

Next, carbon nucleophiles were explored. Indole substrates incorporating a tethered alkene were exposed to the conditions for the formal (3 + 2) cycloaddition, resulting in a conjugate addition/asymmetric protonation/Prins cyclization cascade. In this transformation, the indolinium ion is attacked by the olefin, and the resulting carbocation is quenched by a chloride ion. Zirconium tetrachloride was found to be the optimal Lewis acid. Stoichiometric proton and chloride sources were also found to be crucial for reactivity.

Azaspiracid shellfish poisoning: a review on the chemistry, ecology, and toxicology with an emphasis on human health impacts

Azaspiracids (AZA) are polyether marine toxins that accumulate in various shellfish species and have been associated with severe gastrointestinal human intoxications since 1995. This toxin class has since been reported from several countries, including Morocco and much of western Europe. A regulatory limit of 160 μg AZA/kg whole shellfish flesh was established by the EU in order to protect human health; however, in some cases, AZA concentrations far exceed the action level. Herein we discuss recent advances on the chemistry of various AZA analogs, review the ecology of AZAs, including the putative progenitor algal species, collectively interpret the in vitro and in vivo data on the toxicology of AZAs relating to human health issues, and outline the European legislature associated with AZAs.