Influence of carbon nanotubes on thermal expansion coefficient and thermal buckling of polymer composite plates: experimental and numerical investigations

The first aim of this article is to experimentally explore the effect of multi-walled carbon nanotubes (MWCNTs) on the coefficient of thermal expansion (CTE) of epoxy-based composites. Focusing on the obtained experimental data, two important conclusions can be drawn. (1) Though the CTE of carbon nanotubes (CNTs) is lower than that of neat epoxy, using more CNT does not necessarily decrease the CTE of epoxy polymer. (2) The optimum weight percentage of CNT is 0.3 which can reduce the CTE of epoxy up to 33%. As the second goal of the present research work, thermal buckling analysis of rectangular carbon-fiber-reinforced CNT/epoxy polymer (CFRCNTEP)-laminated composite plates is performed numerically. To this purpose, first, using the obtained experimental data and micro-mechanical models, the thermo-elastic properties of structure are calculated. Then, based on the first-order shear deformation theory (FSDT) and by means of generalized differential quadrature (GDQ) method, the influence of CNTs on the critical buckling temperature of CFRCNTEP composite plates is investigated. The numerical results reveal that MWCNTs can strongly affect thermal buckling behavior of composite plates. It is observed that by adding 0.3 wt. % CNTs into the matrix phase, the critical buckling temperature increases between 35 and 42%

Timing of selective basal ganglia white matter loss in premanifest Huntington’s disease

OBJECTIVES: To investigate the timeframe prior to symptom onset when cortico-basal ganglia white matter (white matter) loss begins in premanifest Huntington's disease (preHD), and which striatal and thalamic sub-region white matter tracts are most vulnerable. METHODS: We performed fixel-based analysis, which allows resolution of crossing white matter fibres at the voxel level, on diffusion tractography derived white matter tracts of striatal and thalamic sub-regions in two independent cohorts; TrackON-HD, which included 72 preHD (approx. 11 years before disease onset) and 85 controls imaged at three time points over two years; and the HD young adult study (HD-YAS), which included 54 preHD (approx. 25 years before disease onset) and 53 controls, imaged at one time point. Group differences in fibre density and cross section (FDC) were investigated. RESULTS: We found no significant group differences in cortico-basal ganglia sub-region FDC in preHD gene carriers 25 years before onset. In gene carriers 11 years before onset, there were reductions in striatal (limbic and caudal motor) and thalamic (premotor, motor and sensory) FDC at baseline, with no significant change over 2 years. Caudal motor-striatal, pre-motor-thalamic, and primary motor-thalamic FDC at baseline, showed significant correlations with the Unified Huntington's disease rating scale (UHDRS) total motor score (TMS). Limbic cortico-striatal FDC and apathy were also significantly correlated. CONCLUSIONS: Our findings suggest that limbic and motor white matter tracts to the striatum and thalamus are most susceptible to early degeneration in HD but that approximately 25 years from onset, these tracts appear preserved. These findings may have importance in determining the optimum time to initiate future disease modifying therapies in HD

P82 238. ¿Es segura la reintervención dejando los injertos arteriales permeables sin clampar?

ObjetivoEl objetivo de no dañar la arteria mamaria evitando su disección y clampaje supone un reto para la protección miocárdica debido al lavado de la cardioplejía.Presentamos nuestra experiencia en reintervenciones sin disecar ni clampar los injertos arteriales.Material y métodosDesde septiembre de 2000 hasta febrero de 2010 se realizaron 29 reintervenciones en 28 pacientes, (89,7% varones), edad media 73,17±7,38años. Las causas de reoperación fueron: progresión de valvulopatía 17 pacientes (58,6%), endocarditis 10 (34,4%), disfunción protésica no estructural 2 (6,9%). La mediana del EuroS-CORE logístico fue 14,84 (4-77,25). La cirugía fue urgente en 7 pacientes. Se realizó sustitución valvular aórtica aislada en 18 y se asoció revascularización en 4, sustitución/plastia mitral en 4, sustitución de aorta en 2; sustitución mitral aislada en 1.La protección miocárdica se realizó con cardioplejía hemática con esmolol, K+ y Mg+, administrándola siempre que no dificultaba el trabajo quirúrgico (intervalos nunca > 20min). Temperatura sistémica media 32,26±3,23 °C.ResultadosLa mediana del tiempo de circulación extracorpórea (CEC) fue 153 (91-494) y de clampaje 103 (71-430)min. Presentaron infarto postoperatorio 1 paciente (3,4%) y síndrome de bajo gasto postoperatorio 2 pacientes (6,5%). La mediana de troponina I postoperatoria fue 7,03ng/ml (1,84-109,5). La mortalidad hospitalaria fue 3 pacientes (10,3%) (cirugía urgente por endocarditis). Las causas de mortalidad fueron: daño neurológico irreversible (1 paciente), sepsis y bajo gasto (2 pacientes). La mediana de estancia hospitalaria fue 7 (1-33) días.ConclusiónEn nuestra experiencia, sin clampar los injertos arteriales y con la estrategia descrita, la protección miocárdica parece adecuada y la mortalidad hospitalaria aceptable

The writing on the wall: the concealed communities of the East Yorkshire horselads

This paper examines the graffiti found within late nineteenth and early-twentieth century farm buildings in the Wolds of East Yorkshire. It suggests that the graffiti were created by a group of young men at the bottom of the social hierarchy - the horselads – and was one of the ways in which they constructed a distinctive sense of communal identity, at a particular stage in their lives. Whilst it tells us much about changing agricultural regimes and social structures, it also informs us about experiences and attitudes often hidden from official histories and biographies. In this way, the graffiti are argued to inform our understanding, not only of a concealed community, but also about their hidden histor

Evaluation of Light Sources for Machine Vision

.R. 1997. Evaluation of light sources for machine vision. Can. Agric. Eng. 39:309-315. Using a color machine vision system, three types of light sources, incandescent, halogen, and fluorescent lamps were evaluated. The fluorescent lamp was also tested with a light controller incorporated as part of its power supply. Output gray levels from the three bands of the camera (red, green, and blue) were recorded for a range of lamp supply voltages and for an 8 h period with constant lamp supply voltages. Illumination uniformities over the field of view (FOV) of the camera were also examined. Given a I V change from the rated supply voltage, the maximum changes among the three color components occurred in the blue (1.8%), blue (1.3%), green (0.5%), and green (0.5%) bands for the incandescent, halogen, fluorescent, and controlled fluorescent lamps, respectively. Under constant lamp voltages for an 8 h period, the lamp outputs decreased by 4.7, 5.0, 7.7, and 1.2%, for the incandescent, halogen, fluorescent, and controlled fluorescent lamps, respectively. The illumination levels over the FOV were uniform, with average column intensities varying by less than 2.1, 2.1, 3.1, and