Analysis of high-temperature creep experiments by generalized nonlinear inversion

The present paper aims at showing that rheological equations can be obtained from creep experiments with better accurracy and reliability if the ‘generalized nonlinear inversion’ method is used rather than the more traditional linear or multi-linear regression methods. The experimental data with the relevant experimental errors can be fitted to nonlinear creep laws whose parameters are then determined. The standard deviation of the creep parameters can also be estimated. An analysis of high temperature creep data of sodium chloride single crystals is given as an example.     

13C nuclear magnetic resonance study of 17 alpha-substituted estradiols

We report the 13C NMR data for 20 compounds bearing a substituent (alkyl, alkenyl, alkynyl, alkylamide, spiro-gamma-lactone, phenyl, benzyl, naphthyl, etc.) at the 17 alpha-position of estradiol. The carbon assignments were done using 1D and 2D NMR experiments (distortionless enhancement by polarization transfer, homonuclear correlated spectroscopy, heteronuclear shift correlation, and heteronuclear shift correlation via long-range couplings). Only the chemical shifts of carbons 12-18, which surround the substitution site, were affected by the addition of a substituent. The magnitude of the effects (shielding or deshielding) was influenced by the 17 alpha-substituent. The individual effects at these carbons were sufficiently distinctive to identify specific centers and should be valuable for signal assignment of a variety of 17 alpha-derivatives of estradiol. In addition to carbon-skeleton assignment, we also report the carbon-substituent assignments.     

Geometrical considerations in analyzing isotropic or anisotropic surface reflections

The bidirectional reflectance distribution function (BRDF) represents the evolution of the reflectance with the directions of incidence and observation. Today BRDF measurements are increasingly applied and have become important to the study of the appearance of surfaces. The representation and the analysis of BRDF data are discussed, and the distortions caused by the traditional representation of the BRDF in a Fourier plane are pointed out and illustrated for two theoretical cases: an isotropic surface and a brushed surface. These considerations will help characterize either the specular peak width of an isotropic rough surface or the main directions of the light scattered by an anisotropic rough surface without misinterpretations. Finally, what is believed to be a new space is suggested for the representation of the BRDF, which avoids the geometrical deformations and in numerous cases is more convenient for BRDF analysis.     

Heavy metal removal from water using the metallogelation properties of a new glycolipid biosurfactant

Water pollution by heavy metals is a problem in both western and developing countries. Heavy metal pollution can be associated with human activity, such as wastewaters from processing of ore mining, but also to simple contamination from metal-rich soils. Whichever the case, chemical and physical methods are generally employed to depollute water. Since most chemicals are themselves polluting agents, there is an increasing interest in finding biobased and biodegradable alternative chemicals, both efficient in removing metals and benign to the environment. Biosurfactants are green chemicals produced by fermentation of yeasts and bacteria and with a good environmental score. Among many applications, this class of compounds has been used to remove heavy metals from contaminated soils. Within this framework, we propose a new mechanism of depolluting water using a glucolipid biosurfactant, G-C18:1, composed of glucose (G) and a C18:1 fatty acid (oleic acid). This compound is able to form a metallogel by complexing cations in water, thus trapping heavy metals (Cu²⁺, Ni²⁺, Cr²⁺, and Co²⁺) in the gel phase. This mechanism allows to remove up to 95% for cobalt and 88 ± 10%, 80 ± 3%, and 59 ± 6% for Cu²⁺, Ni²⁺, and Cr²⁺, respectively. A dedicated structural study shows that this is possible because positively charged species induce gelation of G-C18:1 through a micelle-to-wormlike phase transition, most likely driven by a charge neutralization process. This work shows that wise control of the nanoscale properties of green chemicals can strongly benefit to develop a sustainable future.     

Understanding the impact of BIM on collaboration: a Canadian case study

ABSTRACT

Facilitating collaboration amongst project stakeholders in the construction industry is one of the central tenants of building information modelling (BIM). While there is increasing evidence of the positive influence of BIM on project outcomes, ambiguity remains around BIM’s true impact on collaboration. The presented case study aims to develop insights into the impact of BIM on collaboration in the architecture, engineering and construction industry. A critical realist perspective was adopted and a systematic combining approach was employed to support data collection and analysis. Data were collected through a longitudinal case study of a large design–build project in Canada. The unit of analysis was the individual project team member. Five cognitive determinants identified from the analysis are seen to inform an individual’s framing of event patterns in the context of BIM-enabled collaboration: requirements, expectations, intentions, incentives and capabilities. From this perspective, the impact of BIM on collaboration is understood as a reshaping of an individual’s cognitive determinants, which influence a team member’s framing of event patterns enacted throughout project delivery. This shift is manifested by changing information landscapes, i.e. sources and flows of information, that are generated, shared and consumed within the project team.