Growth of aligned carbon nanotubes on carbon microfibers by dc plasma-enhanced chemical vapor deposition

It is shown that unidirectionally aligned carbon nanotubes can be grown on electrically conductive network of carbon microfibers via control of buffer layer material and applied electric field during dc plasma chemical vapor deposition growth. Ni catalyst deposition on carbon microfiber produces relatively poorly aligned nanotubes with significantly varying diameters and lengths obtained. The insertion of Ti 5 nm thick underlayer between Ni catalyst layer and C microfiber substrate significantly alters the morphology of nanotubes, resulting in much better aligned, finer diameter, and longer array of nanotubes. This beneficial effect is attributed to the reduced reaction between Ni and carbon paper, as well as prevention of plasma etching of carbon paper by inserting a Ti buffer layer. Such a unidirectionally aligned nanotube structure on an open-pore conductive substrate structure may conveniently be utilized as a high-surface-area base electrodes for fuel cells, batteries, and other electrochemical and catalytic reactions

Control of carbon nanotube morphology by change of applied bias field during growth

Carbon nanotube morphology has been engineered via simple control of applied voltage during dc plasma chemical vapor deposition growth. Below a critical applied voltage, a nanotube configuration of vertically aligned tubes with a constant diameter is obtained. Above the critical voltage, a nanocone-type configuration is obtained. The strongly field-dependent transition in morphology is attributed primarily to the plasma etching and decrease in the size of nanotube-nucleating catalyst particles. A two-step control of applied voltage allows a creation of dual-structured nanotube morphology consisting of a broad base nanocone (~200 nm dia.) with a small diameter nanotube (~7 nm) vertically emanating from the apex of the nanocone, which may be useful for atomic force microscopy

Multilab Direct Replication of Flavell, Beach, and Chinsky (1966): Spontaneous Verbal Rehearsal in a Memory Task as a Function of Age

Work by Flavell, Beach, and Chinsky indicated a change in the spontaneous production of overt verbalization behaviors when comparing young children (age 5) with older children (age 10). Despite the critical role that this evidence of a change in verbalization behaviors plays in modern theories of cognitive development and working memory, there has been only one other published near replication of this work. In this Registered Replication Report, we relied on researchers from 17 labs who contributed their results to a larger and more comprehensive sample of children. We assessed memory performance and the presence or absence of verbalization behaviors of young children at different ages and determined that the original pattern of findings was largely upheld: Older children were more likely to verbalize, and their memory spans improved. We confirmed that 5- and 6-year-old children who verbalized recalled more than children who did not verbalize. However, unlike Flavell et al., substantial proportions of our 5- and 6-year-old samples overtly verbalized at least sometimes during the picture memory task. In addition, continuous increase in overt verbalization from 7 to 10 years old was not consistently evident in our samples. These robust findings should be weighed when considering theories of cognitive development, particularly theories concerning when verbal rehearsal emerges and relations between speech and memory

The future use of pathogen-inactivated platelet concentrates

A bibliometric analysis of the existing literature with the most impact on the subject creation of technology based enterpri-ses originated in universities is elaborated, in such a way that this selection can help build a theoretical framework based on a systematic and thorough lite-rature review. Following a des-criptive/transverse design, it is pretended to contribute with information to the community of researchers related to the evolution and impact of the published articles on this matter.In order to complete the data collection, two sets of words were used, these were entered in the search engine of the data bases: Science Direct, Emerald Insight, Springer Link, Redalyc and Scopus, since those are important sources of investiga-tions and articles trustworthy on the subject. The main fin-dings are that; the areas where ithe subject is mostly developed are Business, Administration and Accounting. The coun-try with the most publications about the subject is Italy, the journal that publishes the most about it is Research Policy and one of the most representative universities is Gent (Belgium). Three collaboration networ-ks were also identified, one of them led by Mike Wright, who individually is the most produc-tive author and the one with the most impact on the subject of university spin-offs.Se realiza un análisis bibliométrico de la literatura existente que ha tenido mayor impacto sobre el tema de creación de empresas de base tecnológica de origen universitario, el cual permite observar el desarrollo de la literatura enfocada en este tema de manera que a partir de ésta selección se pueda construir en posteriores estudios un marco teórico con base en una revisión sistemática y exhaustiva de la literatura. Siguiendo un diseño de tipo descriptivo/longitudinal, se pretende aportar información a la comunidad de investigadores en relación con la evolución y el impacto de los artí­culos publicados. Para llevar a cabo la recolección de datos se utilizaron dos juegos de palabras, éstas se introdujeron en los motores de búsqueda de Science Direct, Emerald Insight, SpringerLink, Redalyc y Scopus, ya que significan bases de datos importantes para la búsqueda de investigaciones y artí­culos confiables en este tipo de temas. Los principales hallazgos obtenidos son que, el área donde más se desarrolla es en Negocios, Administración y Contabilidad. El paí­s con más publicaciones es Italia, la revista que más publica sobre este tema es Research Policy y una de las universidades más representativas es la de Gent (Bélgica). También se identificaron tres redes de colaboración, una de los cuales es liderada por Mike Wright que individualmente es el autor más productivo y con mayor impacto en el tema de las spin-off universitaria