Effect of polypropylene fibre reinforced mortars on steel reinforcement corrosion induced by carbonation

Low amounts of polypropylene fibres are added to concrete as a secondary reinforcement to control cracking. Whether this addition might improve the corrosion resistance of the concrete reinforcement by increasing the resistance to carbonation, via reducing penetrating paths, is the subject addressed in the present paper. Crack control by the fibres in plastic state mortars and crack evolution with time have been studied. Furthermore, the influence of crack width on the steel bar corrosion induced by carbonation has also been monitored. Circular specimens made of mortar have been employed in the experimental phase of the study, using a water/cement ratio of 0.50 and cement/sand ratio of 2/1. The polypropylene fibre content was 0% and 0.5% by volume. Low modulus polypropylene fibres may control the crack width in specimens subjected to inadequate curing conditions. No relationship between crack width and time for corrosion initiation has been observed. However, a beneficial effect of fibre addition on the corrosion rate was found.     

Cycles in wavelength routed optical networks

Signals in wavelength routed optical networks can oscillate in closed cycles resulting in adverse effects on network operation. In particular, amplified spontaneous emission from erbium doped fiber amplifiers can form recirculating loops that lead to amplifier saturation and oscillations. Searching, enumerating and eliminating these closed cycles becomes a problem that the network designer must address. A variety of cross-connect technologies are studied and shown to result in oscillating cycles in the network. Topological and technological approaches based on Eulerian network theory and other methods are proposed to eliminate these cycle problems     

Microwave Heated Chemical Vapor Infiltration: Densification Mechanism of SiCf/SiC Composites

Silicon carbide fiber-reinforced silicon carbide matrix composites (SiC_f/SiC) have been produced using microwave heated chemical vapor infiltration. Preferential densification of the composite from the inside out was clearly observed. Although an average relative density of only 55% was achieved in 24 h, representative of an ∼26% increase over the initial fiber vol%, the center of the preform densified to 73% of the theoretical. The densification mechanisms were investigated using X-ray absorptiometry and scanning electron microscopy. The initial inverse temperature profile obtained, which was found to result in the efficient filling of the intratow porosity, although not the intertow porosity, flattened out after approximately 6 h as the densification front moved outward toward the edges. Although not investigated directly, the evidence suggested that this was caused by changes in both the thermal conductivity and microwave absorption characteristics as the samples densified.     

Studies on an araldite-based membrane of copper hexacyanoferrate (III) as a caesium ion-sensitive electrode

Solid membranes of copper hexacyanoferrate (III) in araldite are evaluated as a caesium ion-sensitive electrode. The electrode can be used for caesium determination in the concentration range of 10⁻¹ to 10-⁴M . The potentials generated across the membrane are reproducible and steady potentials are attained in about 1 to 2min. The same electrode can be used over a period of 6 months without significant change in potential. The electrode can be used in the pH ranges 2.5–6.0 at 10⁻² M Cs⁺ and 3.0–6.0 at 10⁻³ M CS⁺, and in presence of a number of interfering ions. Potentiometric titration of caesium nitrate with 12-moIybdophosphoric acid was also carried out using the membrane as an end point indicator.     

Use of a computer for the optimal results of treatment of diabetes mellitus with insulin

The authors present material on the optimization of diabetes mellitus treatment, with the aid of a computer. There were 320 patients under observation. Mathematical models describing the process of the patients treatment and permitting to pronosticate the blood and urine sugar level during the treatment were developed. The use of the imitation experiment on a computer permitted to test several therapeutic variants for the given patient and to choose the optimum one, leading to the most rapid compensation. The second task consisted in the maintenance in the patients of blood glucose variations within definite limits, in the course of 24 hours. An individual model of blood glucose dynamics in the course of 24 hours is set on the computer, and then the optimal scheme of insulin treatment is chosen. Practical testing of such scheme showed its efficacy.     

Diffusivity,shrinkage and simulated drying of litchi fruit (Litchi Chinensis Sonn.)

Litchi (Litchi Chinensis Sonn.) is an important commercial fruit in Thailand and Vietnam. Litchi fruit is consumed both as fresh and dried products. Also most of the export of litchi is in the form of dried whole litchi fruit. Thermo-physical properties and drying model of litchi fruit is important for optimum design of litchi dryer. This paper presents moisture diffusivity, shrinkage and finite element simulated drying of litchi fruit. The moisture diffusivities of litchi were determined by minimizing the sum of square of deviations between the predicted and experimental values of moisture content of thin layer drying under controlled conditions of air temperature and relative humidity. The components in the form of cylinder for seed and seed stalk and slab for seed coat, shell and flesh were dried in thin layers at the air temperatures of 50, 60, 70 and 80 °C and relative humidity in the range of 10–25%. The mean diffusivity of flesh, seed and shell of litchi fruit increased with temperature and was expressed by the Arrhenius-type equation, but the diffusivities of seed coat and seed stalk were independent of temperature. The moisture diffusivities of seed coat and seed stalk were much lower than those of the other parts of the litchi. The shrinkage of litchi fruit has also been determined experimentally and it was expressed as a function of moisture reduction. A two-dimensional finite element model has been developed to simulate moisture diffusion in litchi fruit during drying. Shrinkage of the flesh and different component diffusivities of litchi during drying were also taken into account. The finite element model was programmed in Compaq Visual FORTRAN version 6.5. This finite element model satisfactorily predicts the moisture diffusion during drying. Moisture contents in the different components in the litchi fruit during drying were also simulated. This study provides an understanding of the transport processes in the different components of the litchi fruit.     

Application of ATP bioluminescence for evaluation of surface cleanliness of milking equipment

The ATP bioluminescence method was used to evaluate the cleanliness of milking equipment surfaces (teat cup rubbers, teat dip containers, milk receivers, and pipeline joints) in dairy farms in Galicia (northwest Spain) with parlour, pipeline tie-stall or bucket tie-stall milking systems. The cleanest surfaces were teat cup rubbers. The use of non-chlorinated water for cleaning, and of pipeline or bucket tie-stall milking systems, was associated with high ATP bioluminescence values. However, ATP bioluminescence values only explained 12% of the variability in bulk-tank bacterial count; this is attributable to the importance of other factors (notably the correct functioning of the tank cooling system) for maintenance of low bacterial count.     

Neuroscience and architecture: What does the brain tell to an emotional experience of architecture via a functional MR study?

Environment psychologically affects individuals. According to the base of cognitive psychology, there is a direct relationship between human behavior, environment, and emotional process. Assuming that pleasantness and unpleasantness are associated with peripheral nervous system activation, the current study aims to explore if the pleasant or unpleasant architectural places can stimulate the brain regions engaged in emotions or not. As the main contribution, we used functional magnetic resonance imaging (fMRI) measuring blood oxygenation level-dependent (BOLD) changes to effectively detect the brain's region that mainly responds to the emotional-perceptual processes. Based on the results of examining the emotional assessment model of “Pleasure-Arousal” applied to 140 students, 30 most-rated images representing 15 pleasant and 15 unpleasant places were shown to 32 participants in a 1.5-T MRI scanner. After applying standard preprocessing steps (re-alignment, slice-timing, co-registration, segmentation, normalization, and smoothing) to functional MR images, first-level analysis was applied to each subject. The results were evaluated using statistical corrections at different levels for female and male participants with the second-level analysis. In conclusion, it has been shown that there is a significant linkage between environmental experience and brain activation so that the architectural qualities can change blood flow in specific brain regions.