Search results for "engineering.material"
showing 10 items of 2352 documents
A new view on the kinetics of tricalcium silicate hydration
2016
Abstract C3S hydration is an interesting example of chemical coupling between C3S dissolution, C–S–H and portlandite precipitation. It occurs because Ca2 +, OH− and silicate ions are present in C3S, in both hydration products and in the surrounding solution. Various experimental data sets reveal that the undersaturation with respect to C3S always increases when C3S hydration enters into the deceleratory phase, leading to the conclusion that C3S dissolution is at the origin of this deceleration, not C–S–H growth. In addition, as soon as portlandite precipitates, the dissolution limits the hydration already in the acceleratory hydration step. The evolution of the undersaturation cannot accoun…
New advances in the 3D characterization of mineral coating layers on paper
2008
Summary The surface characteristics of a large set of commercial lightweight coated paper grades are explored. The quantification of the 3D structure is revealed by atomic force microscopy, laser profilometry and X-ray microtomography. This comprehensive study demonstrates the suitability of different and modern methods for assessing critical coating layer properties, thus identifying the right tools for specific structural analyses. Based on the assessment of the top and bottom surfaces of 25 commercial lightweight coated samples, three main conclusions can be drawn: (1) the facet orientation polar angle is a function of roughness, (2) skewness did not describe the surface details affectin…
Effect of environmental humidity and coating on aroma transfer through treated papers
2012
Abstract Coupled transfers of aroma compounds and water vapour were investigated by varying the relative humidity gradient of storage (50% or 90%) of two paper packaging at 25 °C. These papers differed in their coating surface: both were identically impregnated then supercalendered, and only one was twice coated on both sides with a synthetic barrier substance. Permeability and solubility coefficients were determined. The coating treatment was more effective to decrease the permeabilities of water vapour and ethyl ester than the effect of RH. On the contrary, the RH modified the water content of the treated papers and affected more strongly their permeability and solubility to cis-3-hexenol…
Magnetometry with Nitrogen-Vacancy Centers in Diamond
2016
This chapter covers magnetic sensing with nitrogen-vacancy (NV) defect centers in diamond. The NV center fundamentals are introduced and NV optically detected magnetic resonance techniques for dc and ac magnetic sensing are summarized. After reviewing some successful sensing applications, the advantages for using NV magnetometry, as well as some ongoing challenges, are enumerated.
Effect of the indentation process on fatigue life of drilled specimens
2015
Design and manufacture of mechanical elements are strongly influenced by the evaluation of the residual stresses due to their effects on the material strength. This paper presents numerical and experimental results performed on AW 6082-T6 aluminum alloy drilled specimens when the hole is created after a bilateral indentation process. The plastic deformation induced by the indenters creates a compressive residual stress field around the hole, which persists after the drilling operation. Several numerical analysis have been carried out in ANSYS APDL explicit solver for different indentation depths and hole diameters in order to evaluate the compressive circumferential stresses, optimal proces…
Synthesis of Hierarchically Grown ZnO@NT-WS2 Nanocomposites
2009
A chemically specific and facile method for growth of ZnO nanorods on WS2 nanotubes (NT-WS2) is reported. The modification strategy is based on the chalcophilic affinity of Zn, which serves as an anchor to immobilize ZnO colloids onto the WS2 nanotubes. The surface bound ZnO colloids have been used as a seed to grow ZnO nanorods on WS2 nanotubes. The immobilization of ZnO colloids was monitored by UV−vis spectroscopy and photoluminescence spectroscopy whereas the growth of ZnO nanorods was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
Conduction band polarization in some CMR materials
2000
First principles electronic structure calculations reveal certain important common features in the conduction band polarization of many of the newly examined colossal magnetoresistance (CMR) materials. Most CMR compounds seem to possess a localized, magnetic band slightly below the Fermi energy. This localized band transfers polarization to a relatively broad conduction band. The nature of the two bands in different systems can be quite distinct. In the perovskite-derived manganese oxides, the magnetic band is derived from $Mn t_{2g}$ states while the conduction band is derived from Mn e states. In the chalcospinel $Fe_{^0.^5}$ $Cu_{^0.^5}$ $Cr_{2}$$ S_{4}$ , the $Crt_{2g}$ states which are…
Evaluation of sewage sludge-based compost by FT-IR spectroscopy
2006
The aerobic batch composting fermentations of sewage sludge with wood chips and maturity compost as co-composting additives were carried out in an open type lab-scale reactor. Fourier transform infrared spectroscopy (FT-IR) spectroscopy was used to monitor the composting process, evaluate the degradation rate and thus determine the maturity. Although the composition of the input mixture strongly affects the shape of the infrared (IR) spectra, typical bands of components can be selected and used to follow the composting process. The appearance, shape and intensity of the nitrate band at 1384 cm 1 was well pronounced and evident for a sewage sludgebased compost maturity. An increase of the pe…
The impact of organic amendments on soil hydrology, structure and microbial respiration in semiarid lands
2016
Abstract Few studies have considered the effect of organic amendments on soil microbial activity and its contributions to hydraulic conductivity under field conditions in semiarid region soils with different textures and degrees of aggregate stability. This study was performed to investigate the relationship between selected soil properties and hydraulic conductivity in response to different types and application rates of organic amendments. For this purpose, urban municipal solid waste (MSW) compost and alfalfa residue (AR) were applied at different rates of 0 (control), 10 Mg ha− 1 and 30 Mg ha− 1 to clay loam and loamy sand soils under field conditions. Results show that after two years,…
Suitability of Illite Based Clays of Latvia for Chemical and Thermal Activation
2014
Materials has been synthesized in the temperature range from 600-800 0C from illite based clays of Latvia under activation of KOH and NaOH solutions (4-6 M). Compressive strength and apparent porosity were measured. The effect of the concentration of KOH and NaOH solutions on the material mechanical properties was investigated by means of infrared spectroscopy (IR). Compressive strength data of the materials showed that via such activation building materials with good quality can be obtained.