Architectural Control of Freeze-Cast Ceramics Through Additives and Templating

The freezing of concentrated colloidal suspensions is a complex physical process involving a large number of parameters. These parameters provide unique tools to manipulate the architecture of freeze-cast materials at multiple length scales in a single processing step. However, we are still far from developing predictive models to describe the growth of ice crystals in concentrated particle slurries. In order to exert reliable control over the microstructural formation of freeze-cast materials, it is necessary to reach a deeper understanding of the basic relationships between the experimental conditions and the microstructure of the growing solid. In this work, we explore the role of several processing variables (e.g., composition of the suspension, freezing rate, and patterning of the freezing surface) that could affect the formulation strategies for the architectural manipulation of freeze-cast materials. We also demonstrate, using freeze-cast lamellar structures, that reducing the lamellar thickness by less than half increases the compressive strength by more than one order of magnitude.     

Is automatic disinfection between each endoscopy mandatory? Société Royale Belge de Gastro-entérologie

PURPOSE: The effects of chronic chloroquine administration on serum proteins and free amino acids of rabbits and the accompanying ultrastructural changes in the retina were investigated. METHODS: Thirty pigmented rabbits were injected intramuscularly with chloroquine diphosphate (14 mg/Kg bw). Fifteen rabbits served as control. Blood samples drawn after 1, 2, 3, 4, 5, 6 and 12 months were assayed for serum proteins by Bio-analytic kits and horizontal electrophoretic technique. Free amino acids were determined by Beckman analyzer. Central retinal tissue was fixed in 4% glutaraldehyde, embedded in araldite CY212 and sectioned for ultrastructural examination. RESULTS: Histopathologic changes were apparent within three months, initially affecting the pigment epithelium and photoreceptors and later involving the remaining neuroretinal layers. Hypoproteinemia gradually developed mainly due to a sharp drop in albumin and alpha 1 and 2 globulin fractions, inspite of an increase in beta and gamma globulin fractions. The concentration of non-essential amino acids varied considerably from a depletion of taurine, aspartine, glutamine, tryptophan and arginine to an increase of serine, alanine, GABA and ornithine. The most outstanding effect was the disappearance of tyrosine and its return to normal value at the end of the experiment. CONCLUSION: The disturbances in protein pattern and free amino acid levels are an indication of chloroquine toxicity and may be implicated in the retinopathy.     

Pulmonary plasmacytoma. Apropos of a case. Review of the literature]

Thirty-six infants born at term who developed hyperbilirubinemia were assessed for developmental status at 2, 4, 6, 9 and 12 months of age according to a mental and psychomotor scale for 0-4 year old. The development quotient (DQ) of infants with hyperbilirubinemia were lower than controls, and the reduction was significant at 2 months of age (P = 0.03). When single component of DQ was compared, it was shown that the DQ score for social behavior was significantly lower in patients at 2 months of age than in control (P = 0.007), and except for motor, other four single DQ scores were lower in patients than in control and the reduction was significant in the DQ scores for adaptability and social behavior (P = 0.05, 0.032, respectively). Furthermore, no significant correlation was found between DQ and serum peak bilirubin value or duration of hyperbilirubinemia. The results indicate that hyperbilirubinemia may have a long term impact on mental development of infants. It is necessary to monitor all infants with hyperbilirubinemia, including full term infants with no severe complication.     

Object exploration and reactions to spatial and nonspatial changes in hooded rats following damage to parietal cortex or hippocampal formation.

Hooded rats with bilateral lesions of the anterior part of the hippocampal formation (HIP), anterior region of the posterior parietal cortex (APC), or posterior region of the posterior parietal cortex (PPC) were compared with controls for their exploration of 5 objects in an open field, habituation of locomotion and object investigation, and response to spatial and nonspatial change. First, all groups displayed habituation of both locomotor and exploratory activity. Second, controls selectively reexplored displaced objects, and APC-lesioned rats reexplored all objects, whereas PPC- and HIP-lesioned rats failed to react to the spatial change. Third, a novel object induced reexploration in all groups. Results are consistent with the roles of the HIP and PPC in spatial information processing. Moreover, the APC and PPC are involved in attentional effortful processing and visuospatial information processing necessary for spatial representation, respectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mobile Robot Command by Man–Machine Co-Operation – Application to Disabled and Elderly People Assistance

Disabled people assistance is developing thanks to progress of new technologies. A manipulator arm mounted on a mobile robot can assist a disabled person for a partial restoration of the manipulative function. A user pilots the robot via a control station, using enhanced reality techniques. To be affordable such a system must be cost-effective. That constraint limits perception means: ultrasonic ring, dead reckoning, and low-cost camera. The development of the project has followed two stages. The first one consists of giving maximum autonomy capacities to the robot for planning, navigation, and localisation. The second stage is the study of the Man–Machine Co-operation (MMC) for the command of the robot system. Indeed, the aim is to perform a mission (mobile robot displacement), using the robot capacities and man possibilities. Users build their own strategies to carry out a mission successively. The strategy can be seen as a succession of control modes, which can be manual, automatic, or shared. In the latter case, the control of the robot is shared between a human operator and machine. The main problem is then task allocation between both intelligent entities. Each one has planification, navigation, and localisation abilities. The paper presents our approach for planning and navigation and develops a more specific study about robot localisation.     

Crystal growth of bullet-shaped magnetite in magnetotactic bacteria of the Nitrospirae phylum

Magnetotactic bacteria (MTB) are known to produce single-domain magnetite or greigite crystals within intracellular membrane organelles and to navigate along the Earth''s magnetic field lines. MTB have been suggested as being one of the most ancient biomineralizing metabolisms on the Earth and they represent a fundamental model of intracellular biomineralization. Moreover, the determination of their specific crystallographic signature (e.g. structure and morphology) is essential for palaeoenvironmental and ancient-life studies. Yet, the mechanisms of MTB biomineralization remain poorly understood, although this process has been extensively studied in several cultured MTB strains in the Proteobacteria phylum. Here, we show a comprehensive transmission electron microscopy (TEM) study of magnetic and structural properties down to atomic scales on bullet-shaped magnetites produced by the uncultured strain MYR-1 belonging to the Nitrospirae phylum, a deeply branching phylogenetic MTB group. We observed a multiple-step crystal growth of MYR-1 magnetite: initial isotropic growth forming cubo-octahedral particles (less than approx. 40 nm), subsequent anisotropic growth and a systematic final elongation along [001] direction. During the crystal growth, one major {111} face is well developed and preserved at the larger basal end of the crystal. The basal {111} face appears to be terminated by a tetrahedral–octahedral-mixed iron surface, suggesting dimensional advantages for binding protein(s), which may template the crystallization of magnetite. This study offers new insights for understanding magnetite biomineralization within the Nitrospirae phylum.     

Sex differences in research funding,productivity and impact: an analysis of Québec university professors

Using the entire population of professors at universities in the province of Quebec (Canada), this article analyzes the relationship between sex and research funding, publication rates, and scientific impact. Since age is an important factor in research and the population pyramids of men and women are different, the role of age is also analyzed. The article shows that, after they have passed the age of about 38, women receive, on average, less funding for research than men, are generally less productive in terms of publications, and are at a slight disadvantage in terms of the scientific impact (measured by citations) of their publications. Various explanations for these differences are suggested, such as the more restricted collaboration networks of women, motherhood and the accompanying division of labour, women’s rank within the hierarchy of the scientific community and access to resources as well as their choice of research topics and level of specialization.     

Validation of a supervisory control system for energy savings in membrane bioreactors

The application of fixed operational protocols and settings for membrane bioreactors (MBR) often leads to suboptimal filtration conditions due to the dynamic nature of mixed liquor characteristics. With regard to process optimization and energy savings, the potential benefits of a dynamic control system, enabling to adapt fouling control actions (ACS outputs) in an automated way to the actual mixed liquor fouling propensity, are thus obvious. In this paper, the pilot-scale validation of such an advanced control system (ACS) is elaborated. A specific on-line fouling measurement method, the MBR-VFM (VITO Fouling Measurement), was used for the evaluation of the mixed liquor’s reversible fouling propensity, which was used as a primary ACS input parameter. A first series of tests with a gradual increase in complexity of the selected input and output parameters indicated the functionality of the ACS and demonstrated a substantial reduction of aeration, however sometimes at the expense of a higher fouling rate. The ACS was further fine-tuned and subsequently tested for a longer period under more dynamic operating conditions. A significant correlation was found between the reversible fouling potential measured by the MBR-VFM and the on-line permeability, indicating that the MBR-VFM is a suitable ACS input. Furthermore, an average 22% reduction in aeration flow to the membranes could be achieved without any obvious negative effect on filtration performance. This indicates that this approach is promising to optimize energy consumption in MBRs.