53 research outputs found
Monitoring of northern climate exposure
Currently, facility managers are faced with many advanced decisions
regarding when and how to inspect, maintain, repair or renew existing facilities in a costeffective manner. The evolution of the deteriorations of road structures in reinforced
concrete depends on the exposure of the elements to water in liquid form or vapour and to
other aggressive agents such as chloride. Current models of ionic transport neglect the
effect of real ionic concentration in contact with concrete structures, it means boundary
conditions are considered with simple tendency as uniform concentration during the winter
period and model parameters are derived from the fitting method. Therefore, it implies in
ineffective prediction models of deterioration, i.e. steel rebar corrosion by chloride
presence or carbonation, alkali-granular reaction, acid attacks, etc. Structure are sensitive
to their environment and their interaction with it is directly related to the processes of
deterioration. The degradation of structures exposed to salt-laden mist is faster in the wetter
areas. On the contrary, the deterioration of the structures caused by salt spray in the drier
zone is slower. The structures, exposed to splashing (precipitation, wind, splash, etc.), have
a slower rate of degradation in the wetter regions. The amount of rain has an indirect effect
in the process of deterioration of the structure exposed to salt-laden mist because it changes
the contact time of chloride on the surface of the structures. For this purpose, a unique
exposure monitoring was developed. This mobile station, named MExStUL, contains an
atmospheric sensor and new possibilities of chloride detection contained in splashes, mist
and static water near the road improving the real exposure of structure and the boundary
conditions. First results highlight the real influence of environmental parameters on
structures durability on highways. Salt concentration is not uniform during winter period
and water thickness demonstrate important periods of drying
An Integrated Meta-Analysis of Two Variants in HOXA1/HOXB1 and Their Effect on the Risk of Autism Spectrum Disorders
BACKGROUND: HOXA1 and HOXB1 have been strongly posed as candidate genes for autism spectrum disorders (ASD) given their important role in the development of hindbrain. The A218G (rs10951154) in HOXA1 and the insertion variant in HOXB1 (nINS/INS, rs72338773) were of special interest for ASD but with inconclusive results. Thus, we conducted a meta-analysis integrating case-control and transmission/disequilibrium test (TDT) studies to clearly discern the effect of these two variants in ASD. METHODS AND FINDINGS: Multiple electronic databases were searched to identify studies assessing the A218G and/or nINS/INS variant in ASD. Data from case-control and TDT studies were analyzed in an allelic model using the Catmap software. A total of 10 and 7 reports were found to be eligible for meta-analyses of A218G and nINS/INS variant, respectively. In overall meta-analysis, the pooled OR for the 218G allele and the INS allele was 0.97 (95% CI = 0.76-1.25, P(heterogeneity) = 0.029) and 1.14 (95% CI = 0.97-1.33, P(heterogeneity) = 0.269), respectively. No significant association was also identified between these two variants and ASD risk in stratified analysis. Further, cumulative meta-analysis in chronologic order showed the inclination toward null-significant association for both variants with continual adding studies. Additionally, although the between-study heterogeneity regarding the A218G is not explained by study design, ethnicity, and sample size, the sensitive analysis indicated the stability of the result. CONCLUSIONS: This meta-analysis suggests the HOXA1 A218G and HOXB1 nINS/INS variants may not contribute significantly to ASD risk
Barrel pattern formation requires serotonin uptake by thalamocortical afferents, and not vesicular monoamine release
Thalamocortical neurons innervating the barrel cortex in neonatal rodents transiently store serotonin (5-HT) in synaptic vesicles by expressing the plasma membrane serotonin transporter (5-HTT) and the vesicular monoamine transporter (VMAT2). 5-HTT knock-out (ko) mice reveal a nearly complete absence of 5-HT in the cerebral cortex by immunohistochemistry, and of barrels, both at P7 and adulthood. Quantitative electron microscopy reveals that 5-HTT ko affects neither the density of synapses nor the length of synaptic contacts in layer IV. VMAT2 ko mice, completely lacking activity-dependent vesicular release of monoamines including 5-HT, also show a complete lack of 5-HT in the cortex but display largely normal barrel fields, despite sometimes markedly reduced postnatal growth. Transient 5-HTT expression is thus required for barrel pattern formation, whereas activity-dependent vesicular 5-HT release is not
Influence of microclimate on the probability of initiation of chloride induced corrosion in reinforced concrete
MC
Capillary suction and diffusion model for chloride ingress into concrete
A numerical approach, named TransChlor, is proposed to simulate transport phenomena of various substances in concrete. This approach is a theoretical model based on finite elements and finite differences methods. The model consists of coupled nonlinear partial differential equations based on Fick's diffusion law and on kinematics equations. Simulation results from a parametrical study highlight the influence of microclimatic conditions, exposure to deicing salts and concrete cover permeability and thickness on chloride ingress in concrete. The results show that the chloride ion concentration increases quickly in concrete cover when a structure is exposed to deicing salts at a mountainous location; whereas permeability of concrete cover is an insignificant parameter when the concrete is in direct or splash water contact
Simulation of the corrosion behaviour of concrete elements reinforced with high performance steel
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