Fabrication of Densely Packed AlN Nanowires by a Chemical Conversion of Al2O3Nanowires Based on Porous Anodic Alumina Film

Porous alumina film on aluminum with gel-like pore wall was prepared by a two-step anodization of aluminum, and the corresponding gel-like porous film was etched in diluted NaOH solution to produce alumina nanowires in the form of densely packed alignment. The resultant alumina nanowires were reacted with NH3and evaporated aluminum at an elevated temperature to be converted into densely packed aluminum nitride (AlN) nanowires. The AlN nanowires have a diameter of 15–20 nm larger than that of the alumina nanowires due to the supplement of the additional evaporated aluminum. The results suggest that it might be possible to prepare other aluminum compound nanowires through similar process

Evolutionism and genetics of posttraumatic stress disorder

The authors discuss, from the evolutionary concept, how flight and fight responses and tonic immobility can lead to a new understanding of posttraumatic stress disorder. Through the analysis of symptom clusters (revivals, avoidance and hyperexcitation), neurobiological and evolutionary findings are correlated. The current discoveries on posttraumatic stress disorder genetics are summarized and analyzed in this evolutionary perspective, using concepts to understand the gene-environment interaction, such as epigenetic. The proposal is that the research of susceptibility factors in posttraumatic stress disorder must be investigated from the factorial point of view, where their interactions increase the risk of developing the disorder, preventing a unique search of the cause of this disorder. The research of candidate genes in posttraumatic stress disorder must take into consideration all the systems associated with processes of stress response, such as the hypothalamus-pituitary-adrenal and sympathetic axes, mechanisms of learning, formation and extinguishing of declarative memories, neurogenesis and apoptosis, which involve many systems of neurotransmitters, neuropeptides and neurohormones.Os autores discutem, a partir do conceito evolutivo, como a resposta de estresse, nas suas possibilidades de fuga e luta e de imobilidade tônica, pode levar a uma nova compreensão etiológica do transtorno de estresse pós-traumático. Através da análise dos agrupamentos de sintomas desse diagnóstico - revivência, evitação e hiperexcitação -, procuram correlacionar os achados neurobiológicos e evolutivos. As descobertas atuais sobre a genética do transtorno de estresse pós-traumático são resumidas e colocadas nessa perspectiva evolutiva, dentro de conceitos que possibilitam o entendimento da interação gene/ambiente, como a epigenética. Propõem que a pesquisa dos fatores de risco do transtorno de estresse pós-traumático deva ser investigada do ponto de vista fatorial, onde a somatória destes aumenta o risco de desenvolvimento do quadro, não sendo possível a procura da causa do transtorno de forma única. A pesquisa de genes candidatos no transtorno de estresse pós-traumático deve levar em consideração todos os sistemas associados aos processos de respostas ao estresse, sistemas dos eixos hipotálamo-hipofisário-adrenal e simpático, mecanismos de aprendizado, formação de memórias declarativas, de extinção e esquecimento, da neurogênese e da apoptose, que envolvem vários sistemas de neurotransmissores, neuropeptídeos e neuro-hormônios.Universidade Federal de São Paulo (UNIFESP)(UNIFESP)UNIFESP Departamento de PsiquiatriaUniversidade de São Paulo Faculdade de Medicin Hospital de ClínicasUNIFESP, Depto. de PsiquiatriaSciEL

Neutral dangling bond depletion in amorphous SiN films induced by magnetic rare-earth elements

Amorphous silicon-nitrogen (a-SiN) thin films doped with rare-earth elements (RE = Y, La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Yb, and Lu) were prepared by cosputtering and studied by means of electron spin resonance. It was found that the neutral dangling bond density, [D-0], of the a-SiN films decreases with the presence of magnetic REs and the drop in [D-0] approximately scales with the de Gennes and/or the spin factor of each RE element. Similar to the decrease in T-c in RE-doped superconductors, our experimental results strongly suggest that an exchange-like interaction, H similar to J(RE.D0)S(RE).S-D0, between the spin of the magnetic REs and that of the D-0 is taking place. (C) 2003 Published by Elsevier Ltd.12841700475