Creep Functions for Wood Composite Materials

Two related functions used to describe the creep of non-wood materials were fitted to data for wood composite materials. The first function, which is linear in its constants, was unsatisfactory for representing the creep of plywood, oriented strandboard, laminated timber, and dry-process hardboard under the given loading and environmental conditions. The second function is nonlinear in its constants. Creep of plywood and oriented strandboard were moderately well represented by this function, while creep of laminated timber and hardboard were exceptionally well represented. Experimental creep data and estimates of empirical constants are presented

Flexural Behavior of Glass Fiber Reinforced Hardboard

The flexural stiffness and strength of a dry-process hardboard matrix were significantly improved by internal reinforcement with continuous glass fibers. The dynamic and static moduli of elasticity and the modulus of rupture of glass fiber reinforced hardboard increased with increasing reinforcement volume fraction. When modelled as a sandwich construction, the static flexural modulus of elasticity of the composite could be accurately predicted from the modulus of elasticity of the wood fiber matrix, and the tensile modulus of elasticity and volume fraction of the glass fiber reinforcement. Excellent linear correlation among the dynamic modulus of elasticity, the static modulus of elasticity, and the modulus of rupture allowed for estimation of the composite failure stress from flexural properties that were determined nondestructively. The results of this study will assist in the design of glass fiber reinforced hardboard composites

Creep Behavior of Glass Fiber Reinforced Hardboard

The flexural creep deflection of a dry-process hardboard matrix was significantly reduced by internal reinforcement with continuous glass fibers. The short-term flexural creep of glass fiber reinforced hardboard stressed within the elastic range at constant ambient conditions is well described by a 4-element linear viscoelastic model. Numerical estimates of creep model parameters are presented

Oxidative Stress Detection With Escherichia Coli Harboring A katG\u27::lux Fusion

A plasmid containing a transcriptional fusion of the Escherichia coli katG promoter to a truncated Vibrio fischeri lux operon (luxCDABE) was constructed. An E. coli strain bearing this plasmid (strain DPD2511) exhibited low basal levels of luminescence, which increased up to 1,000-fold in the presence of hydrogen peroxide, organic peroxides, redox-cycling agents (methyl viologen and menadione), a hydrogen peroxide-producing enzyme system (xanthine and xanthine oxidase), and cigarette smoke. An oxyR deletion abolished hydrogen peroxide-dependent induction, confirming that oxyR controlled katG\u27::lux luminescence. Light emission was also induced by ethanol by an unexplained mechanism. A marked synergistic response was observed when cells were exposed to both ethanol and hydrogen peroxide; the level of luminescence measured in the presence of both inducers was much higher than the sum of the level of luminescence observed with ethanol and the level of luminescence observed with hydrogen peroxide. It is suggested that this construction or similar constructions may be used as a tool for assaying oxidant and antioxidant properties of chemicals, as a biosensor for environmental monitoring and as a tool for studying cellular responses to oxidative hazards

Detection Of DNA Damage By Use Of Escherichia Coli Carrying recA\u27::lux, uvrA\u27::lux, And alkA\u27::lux Reporter Plasmids

Plasmids were constructed in which DNA damage-inducible promoters recA, uvrA, and alkA from Escherichia coli were fused to the Vibrio fischeri luxCDABE operon. Introduction of these plasmids into E. coli allowed the detection of a dose-dependent response to DNA-damaging agents, such as mitomycin and UV irradiation. Bioluminescence was measured in real time over extended periods. The fusion of the recA promoter to luxCDABE showed the most dramatic and sensitive responses. lexA dependence of the bioluminescent SOS response was demonstrated, confirming that this biosensor\u27s reports were transmitted by the expected regulatory circuitry. Comparisons were made between luxCDABE and lacZ fusions to each promoter. It is suggested that the lux biosensors may have use in monitoring chemical, physical, and genotoxic agents as well as in further characterizing the mechanisms of DNA repair

Człowiek to „małpa, która nie przestraszyła się ognia”. Wokół listu Kazimierza Brandysa z 18 maja 1994 roku

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Forest Products Research at U.S. Universities in 1988-1989

Professional staffing, research emphasis, and funding levels for forest products research conducted in 37 programs at 35 universities in the United States in academic year 1988-1989 are presented. General trends in academic forest products research for the period 1982 to 1989 are also described

Neurociencia cognitiva, desarrollo de software y educación: ¿La interfaz como puente?

Dos laboratorios de neurociencia emprendieron en colaboración una década atrás el desarrollo de un software de estimulación cognitiva llamado Mate Marote. La propuesta de este trabajo es abordar el desarrollo de este software en particular, reconstruyendo, caracterizando y analizando las condiciones que lo hicieron posible, los criterios, fines y modificaciones realizadas a lo largo de tiempo. Teniendo en cuenta que en este caso el software se presenta como un “puente” entre dos ámbitos tan distintos como el laboratorio y el aula, este artículo invita asimismo a problematizar la interfaz en tanto nexo que configura una escena de aplicación, tornando visible el entramado de actores, criterios e instituciones que allí confluyen.Two neuroscience laboratories collaboratively undertook a decade ago the development of a cognitive stimulation software called Mate Marote. The proposal of this work is to address the development of this particular software, reconstructing, characterizing and analyzing the conditions that made it possible, the criteria, purposes and modifications over time. Taking into account that in this case the software is presented as a "bridge" between two areas as different as the laboratory and the classroom, this work also invites to problematize the interface as a nexus that configures an application context, making visible the network of actors, criteria and institutions that converge in its application scene.Dois laboratórios de neurociência colaboraram há uma década no desenvolvimento de um software de estimulação cognitiva chamado Mate Marote. A proposta deste trabalho é abordar o desenvolvimento deste software em particular, reconstruindo, caracterizando e analisando as condições que tornaram possível, os critérios, propósitos e modificações feitas ao longo do tempo. Levando em conta que, nesse caso, o software é apresentado como uma "ponte" entre duas áreas diferentes, o laboratório e a sala de aula, este artigo também convida a problematizar a interface como um nexo que configura uma cena de aplicação, tornando a estrutura visível de atores, critérios e instituições que aí convergem

Implicancias políticas de los estudios neurocientíficos: Hacia un giro colaborativo interdisciplinario

El crecimiento sostenido del campo neurocientífico a nivel global en las últimas dos décadas fue acompañado de expectativas en relación con los aportes que estos conocimientos podrían hacer al desarrollo de políticas públicas. Una parte de este campo se orientó al estudio de los efectos de las condiciones socioeconómicas adversas sobre el desarrollo del cerebro desde la infancia temprana, dando origen a los estudios de neurociencia y pobreza. Los avances producidos en esta área en particular han despertado debates entre profesionales de distintas disciplinas respecto de las implicancias políticas de las evidencias que se producen y la forma en que ya están siendo utilizadas en distintas narrativas políticas. El año 2019 el Centro Cultural de la Ciencia de Autónoma de Buenos Aires se desarrolló un evento interdisciplinario titulado Usos políticos de la evidencia neurocientífica sobre pobreza. Un encuentro de reflexión y debate. Allí realizó una presentación el destacado sociólogo Nikolas Rose centrada en la revisión e historización de ciertas nociones claves y sus efectos biopolíticos. En su presentación dejó abiertos numerosos interrogantes sobre el papel que podrían jugar la neurociencia en las políticas sobre pobreza e invitó al desarrollo de relaciones colaborativas entre científicos sociales y neurocientíficos. Las páginas que se presentan a continuación y que anteceden a la transcripción de su exposición oral buscan, en primer lugar, enmarcar y contextualizar las discusiones abiertas por Nikolas Rose considerando sus trabajos previos. En segundo lugar, articular su exposición con la problemática específica que nos plantea la noción de giro colaborativo considerando la posibilidad de abordar interdisciplinariamente los debates y tensiones que abre la relación entre neurociencia y política.Fil: Smulski, Mariana Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentin