Physiochemical characterization of five iron tubercles from a single drinking water distribution system: Possible new insights on their formation and growth

Physiochemical data were obtained for five iron tubercles from a single drinking water distribution system (DS). Texturally, there were two groups based on internal morphology: one with a core of soft brownish material marbled with veins of a hard black material, the other has a core consisting mostly of the hard, black material. Three iron mineral phases occur, α-FeOOH, γ-FeOOH, or Fe₃O₄. All three coexist in each tubercle but in widely varying proportions. These iron pipe tubercles exhibit a greater diversity within a single DS than previously thought. Because the chemical conditions for the formation of each material is different, water quality parameters may not be the main control of tubercle formation and growth.     

Preliminary study on cost optimisation of aircraft composite structures applicable to liquid moulding technologies

This paper details the initial development of a method for determining the associated recurring labour costs for the manufacture of a aircraft component that will form the basis for a computerised methodology for determining the optimum manufacturing method for a component design. The research focuses on the flow of process steps to manufacture an aircraft component for the vacuum-assisted resin transfer moulding and resin transfer moulding manufacturing process. The methodology developed is based on applying MIT cost equations to process steps from which cost variables and constants are established to represent an estimated costing of the aircraft structure. This research will assist in providing a swifter and more accurate conceptual design/manufacturing system that includes an analysis of cost and will assist the production of trade studies that consider the manufacture of aircraft components using cost-effective technologies, such as liquid moulding.     

An overview of air emission intensities and environmental performance of grey cement manufacturing in Canada

Air emissions generated in grey cement manufacturing originate primarily from the combustion of fossil fuels required to heat the kiln and the chemical reaction of raw materials in the pyroprocessing phase. Given that the kiln system is enclosed, air emissions generated, discharge from a single point source kiln stack. Unlike other industries, the point source kiln stack enables the cement sector to accurately monitor and record total air emissions. The largest contributors to air emissions from grey cement manufacturing are carbon dioxide (CO₂), oxides of nitrogen (NO _x ), sulphur dioxide (SO₂) and dust/particulate matter (PM). In Canada, grey cement manufacturing facilities are required to annually report these emissions through the National Pollutant Release Inventory (NPRI). Since CO₂, NO _x , SO₂ and PM are the largest contributors to air emissions, and Canadian grey cement facilities are required to report these emissions, combining NPRI data with annual grey cement production data allows for the development of intensity-based environmental performance indicators. Based on data provided by NPRI, in combination with industry production, we can better understand the environmental performance of Canada’s grey cement manufacturing. On the global stage, intensity-based performance measures provide a useful tool for comparison and demonstrate a strong environmental performance for grey cement production in Canada. As an energy intensive and trade exposed (EITE) grey cement manufacturing is vulnerable to unbalanced environmental policy, which may ultimately result in leakage of production and air emissions to developing countries.     

Preparation of periodically organized mesoporous bicomponent TiO2 and SnO2-based thin films by controlling the hydrolytic kinetics of inorganic precursors during EISA process

Highly organized cubic mesoporous TiO₂ and SnO₂ nanocrystalline thin films were reproducibly synthesized via an evaporation-induced self-assembly (EISA) process with a triblock copolymer (Pluronic F127) as the template, by precisely controlling the water content and chelating agent in the initial sol solution as well as by controlling the external relative humidity during the aging step. It has been found that the mesoscopic regularity of the fabricated mesoporous films critically depends on the hydrolytic reactions of inorganic precursors. That is, suppressing the hydrolysis reaction in the initial sol and providing the long-term stability for the sol in the coated film during the aging step are key factors in the formation of highly organized structure. The synthetic strategy was also extended to obtain various TiO₂- and SnO₂-based mixed oxide thin films with tunable composition, including WO₃/TiO₂, SiO₂/TiO₂, Nb₂O₅/SnO₂, by selectively controlling the kinetics of hydrolytic reaction for the additional inorganic precursors. The prepared composite films were crack-free, ultra-highly transparent, and thermally stable.     

Toward global metabolomics analysis with hydrophilic interaction liquid chromatography-mass spectrometry: improved metabolite identification by retention time prediction

Metabolomics is an emerging field of postgenomic biology concerned with comprehensive analysis of small molecules in biological systems. However, difficulties associated with the identification of detected metabolites currently limit its application. Here we demonstrate that a retention time prediction model can improve metabolite identification on a hydrophilic interaction chromatography (HILIC)-high-resolution mass spectrometry metabolomics platform. A quantitative structure retention relationship (QSRR) model, incorporating six physicochemical variables in a multiple-linear regression based on 120 authentic standard metabolites, shows good predictive ability for retention times of a range of metabolites (cross-validated R(2) = 0.82 and mean squared error = 0.14). The predicted retention times improved metabolite identification by removing 40% of the false identifications that occurred with identification by accurate mass alone. The importance of this procedure was demonstrated by putative identification of 690 metabolites in extracts of the protozoan parasite Trypanosoma brucei, thus allowing identified metabolites to be mapped onto an organism-wide metabolic network, providing opportunities for future studies of cellular metabolism from a global systems biology perspective.     

Mechanical Properties of Conjugated Polymers and Polymer‐Fullerene Composites as a Function of Molecular Structure

Despite the importance of mechanical compliance in most applications of semiconducting polymers, the effects of structural parameters of these materials on their mechanical properties are typically not emphasized. This paper examines the effect of length of the pendant group on the tensile modulus and brittleness for a series of regioregular poly(3‐alkylthiophenes) (P3ATs) and their blends with a soluble fullerene derivative, PCBM. The tensile modulus decreases with increasing length of the alkyl side‐chain, from 1.87 GPa for butyl side chains to 0.16 GPa for dodecyl chains. The moduli of P3AT:PCBM blends films are greater than those of the pure polymers by factors of 2–4. A theoretical model produces a trend in the effect of alkyl side chain on tensile modulus that follows closely to the experimental measurements. Tensile modulus correlates with brittleness, as the strain at which cracks appear is 6% for P3BT and >60% for P3OT. Adhesion of the P3AT film to a polydimethylsiloxane (PDMS) substrate is believed to play a role in an apparent increase in brittleness from P3OT to P3DDT. The additive 1,8‐Diiodooctane (DIO) reduces the modulus of P3HT:PCBM blend by a factor of 3. These results could enable mechanically robust, flexible, and stretchable electronics.     

A time-window sliding procedure for driver-task assignment with random service times

This paper addresses the problem of assigning drivers to cover tasks when the tasks are the movements of containers. The tasks must be started within certain time windows and their servicing times are uncertain while the decisions are made over time. These decisions can be changed if new information is received. The problem is formulated in a stochastic optimization framework with the objective of minimizing the costs of current driver-task assignment and the expected future costs. A time-window sliding solution procedure is developed to estimate the expected future costs by solving the minimum cost flow problems iteratively. Furthermore, the results of the numerical experiments that assess the efficiency of the algorithm and the benefits of considering uncertainty in the model are reported.     

Embodied and Operational Energy Consumption in the City

This study shows how estimates of energy consumption can be extracted from existing data sets and efficiently related to characteristics of the real property making up the discrete areas of the city. The study suggests that embodied energy consumption may be more significant than previously thought and suggests how estimates of embodied and operational energy may be used as a development control tool in the planning system.