Internal cracking and transport properties in damaged concretes

The durability of concrete constructions is strongly related with the transport of fluids through the material. The presence of pores and cracks increases the permeability of the material, enhancing the ingress of aggressive agents that contribute to the material degradation. In this sense the internal structure is decisive, mainly the characteristics of the mortar matrix and the aggregates of greater size and its interfaces. In this work the incidence of different types of cracks on the transport properties is analyzed, considering several cases of degradation: concretes damaged by exposure to low humidity conditions or to high temperatures (150 and 500°C), and a concrete affected by alkali-silica reaction (ASR). The characterization of the internal structure was made at the mesostructural level through the assessment of the density and width of cracks; as transport properties the water absorption, capillary absorption, water penetration and coefficient of water permeability were considered. As expected the width, the density and the type of fissures had a strong impact on the transport properties, however each variable will have a higher or lower incidence depending on the transport mechanism involved. In concretes damaged by drying shrinkage the permeability increased steadily with the crack density, however, the capillary absorption after reaching a maximum decreased for cracks of greater width. At the same time in concrete damaged by ASR, differences were found in the water penetration test in accordance with the crack orientations which were not verified in the values of the coefficient of permeability.     

The impact of motivation on temporal comparisons: Coping with traumatic events by perceiving personal growth.

Four studies were conducted to investigate the impact of self-enhancement motivation on the temporal comparisons of victims of stressful life events. Study 1 revealed that (a) victims were more likely than acquaintances of victims to report greater improvement in their personal attributes after traumatic life events than after mild negative life events and (b) victims perceived improvement by derogating their pre-event attributes. In Studies 2 and 3, an experimental approach was used to study the impact of threatening experiences on perceptions of personal growth, and similar findings were obtained. Study 4 confirmed that threatening self-relevant feelings play a causal role in prompting self-enhancing temporal comparisons. Taken together, the findings of these studies support the view that perceptions of personal improvement reflect, at least in part, motivated illusions that are designed to help people cope with threatening life experiences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Space Solar Power: Environmental Questionsand Future Studies

Many environmental issues surrounding space solar power (SSP), with impacts and benefits to the environment, must be addressed. The environmental issues surrounding SSP affect factors such as people, landscape, equipment, and pollution, including physical safety for people and for equipment, social questions connected with aesthetics, politics, and economics, as well as the more general issues of global change and sustainability of energy supply. Wireless power transmission is a key component of SSP systems, and the Grand Bassin wireless power transmission project, currently under development in La Réunion (France), will be a valuable test site for many environmental issues. The facility will allow one to study the environmental integration of the facility, which is the No. 1 priority of the project, and the actual effects of an operational microwave power beam.     

Zipf's law and the diversity of biology newsgroups

Usenet newsgroups provide a popular means of scientific communication. We demonstrate striking order in the diversity of biology newsgroups: Submissions to newsgroups obey a form of Zipf's law, a simple power law for the frequency of posts as a function of the rank, by posting, of contributors. We show that a simple stochastic process, due to Günther et al. (1992, 1996), Levitin and Schapiro (1993), and Schapiro (1994), accounts for this pattern and reproduces many of the properties of newsgroups. This model successfully predicts the relative contribution from each poster in terms of the size, the number of posters and total posts, of the newsgroup. This revised version was published online in August 2006 with corrections to the Cover Date.     

Food poisoning by clenbuterol in Portugal.

This paper describes the occurrence of four cases of acute food poisoning, involving a total of 50 people, due to the ingestion of lamb and bovine meat containing residues of clenbuterol. Symptoms shown by the intoxicated people may be generally described as gross tremors of the extremities, tachycardia, nausea, headaches and dizziness. Analytical methodology developed for the determination of clenbuterol in meat, liver and blood samples is described. Procedures are described which should be followed when the described symptoms are evident in a group of people who have ingested contaminated meat, and particularly liver of ruminants.     

Advances in Biosensors and Diagnostic Technologies Using Nanostructures and Nanomaterials

Nanoscale materials have unique properties that make them especially useful for biomedical diagnostic applications. Recent developments in nanoengineering have resulted in increasing use of nanostructures in biosensors. Various types of 0D, 1D, 2D, and 3D nanostructures have been used to improve biosensor sensitivity, selectivity, limit of detection, and time to result, among other metrics. These nanostructures have been integrated into electrochemical, optical, and other biosensors for this purpose. Here, the most recent advances in the use of nanostructured materials in biosensors are described. This includes a discussion of nanoparticles, nanorods, nanofibers, nanopillars, nanowires, nanosheets, indented nanopatterns (nanoholes and nanoslits), nanogaps, nanochannels, nanopores, nanofunctionalized surfaces, and complex hierarchical structures and their unique advantages and applications in biosensors. Clinical applications of these nanobiosensors are also highlighted along with a discussion of the future directions for these materials in diagnostics.     

High CNT content composites with CNT Buckypaper and epoxy resin matrix: Impregnation behaviour composite production and characterization

This work provides information on the characterization of carbon nanotube (CNT) skeletons, or Buckypapers, using contact angle and thermogravimetric analysis (TGA) measurements. The preparation of composites using these CNT skeletons and an epoxy resin by impregnation in vacuum and cure in two moulds with different release surfaces is described. Preliminary results for the mechanical performance of the produced composites using mini-tensile test specimens and their characterization by TGA, dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM) is also presented.     

Contribution of the rat's neocortex to ingestive control: I. Latent learning for the taste of sodium chloride.

Conducted 3 experiments with 13 decorticate and 12 control male Sprague-Dawley rats to investigate whether some permanent ingestive control deficit would be revealed in a latent learning paradigm for salt taste. The ability of Ss to associate how they obtained the taste of NaCl when Na-replete was assessed by examining barpresses during extinction when Na-depleted. Intact Ss exposed to 4–6 hrs of NaCl taste training retained the association after decortication; decorticate Ss exposed to the same training acquired the association. Decorticate Ss exposed to as little as 2 min of NaCl taste training demonstrated the ability to associate barpressing with NaCl by their resistance to extinction. This association was specific to NaCl training. It is concluded that subcortical structures are adequate for latent learning involving NaCl taste. Conversely, previous research has shown that the neocortex is required for the retention of taste-aversion learning for the same taste. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)