TG, FT-IR and NMR characterization of n-C16H34 contaminated alumina and silica after mechanochemical treatment

This paper deals with the application of mechanochemistry to model systems composed of alumina or silica artificially contaminated with n-C16H34. The mechanochemical treatment was carried out by means of a ring mill for times ranging from 10 to 40 h. Thermogravimetry and infrared and nuclear magnetic resonance spectroscopies were used for the characterization of the mechanochemical products. The results have indicated that, in the case of alumina, almost all the contaminant n-C16H34 undergoes a complex oxidative reaction path whose end products are strongly held on the surface. These end products are most likely made of crosslinked, partially oxidized hydrocarbon chains bond to the solid surface via COO− groups. In the case of silica, the hydrocarbon undergoes a different, equally complex reaction path, but to a lower extent. In this case the end products are most probably carbonylic compounds and graphitic carbon. Then, for both solid matrices, the mechanochemical treatment promotes significant modification of the chemical nature of the polluting hydrocarbon with end products much more difficult to remove from the surface. As the systems studied are models of sites contaminated by aliphatic hydrocarbon, the results are worthy of consideration in relation to the mobility of the contaminants in the environment

engineering thoughts on hydrogen embrittlement

Abstract Hydrogen Embrittlement (HE) is a topical issue for pipelines transporting sour products. Engineers need a simple and effective approach in materials selection at design stage. In other words, they must know if a material is susceptible to cracking, to be able of: selecting the right material and apply correct operational measures during the service life. Following ASTM F2078, HE is "a permanent loss of ductility in a metal or alloy caused by hydrogen in combination with stress, either externally applied or internal residual stress". In many cases, hydrogen can play a role in crack propagation, as for instance in Stress Corrosion Cracking (SCC) and Corrosion Fatigue (CF). Three parameters are required to cause failure: presence of hydrogen, tensile stress, and material susceptibility. The two previous ones are triggering the failure, while the root cause is usually material susceptibility. This is why material selection is the important step to safely manage engineering structural materials. As an example, material selection for sour service pipeline is the object of well-known standards, e.g. by Nace International and EFC: they pose some limits in the sour service of steels, with reference to surface hardness. These standards have shown some weak points, namely: In the definition of sour service; In defining the role of crack initiation and propagation, considering that in Hydrogen embrittlement, stress state and stress variations are very important. As for the second point, in hydrogen generation anodic processes shall be taken into account too. For instance, there is a relationship between corrosion resistance and crack susceptibility. In carbon and low alloy steels, cracking will not normally occur when there is a significant corrosion rate. If a brittle layer (or a brittle spot) is present on the metal surface, this one can initiate a crack

Fibre-reinforced geopolymer concretes for sensible heat thermal energy storage: Simulations and environmental impact

Power plants based on solar energy are spreading to accomplish the incoming green energy transition. Besides, affordable high-temperature sensible heat thermal energy storage (SHTES) is required. In this work, the temperature distribution and thermal performance of novel solid media for SHTES are investigated by finite element method (FEM) modelling. A geopolymer, with/without fibre reinforcement, is simulated during a transient charging/discharging cycle. A life cycle assessment (LCA) analysis is also carried out to investigate the environmental impact and sustainability of the proposed materials, analysing the embodied energy, the transport, and the production process. A Multi-Criteria Decision Making (MCDM) with the Analytical Hierarchy Process (AHP) approach, taking into account thermal/environmental performance, is used to select the most suitable material. The results show that the localized reinforcement with fibres increases thermal storage performance, depending on the type of fibre, creating curvatures in the temperature profile and accelerating the charge/discharge. High-strength, high-conductivity carbon fibres performed well, and the simulation approach can be applied to any fibre arrangement/material. On the con-trary, the benefit of the fibres is not straightforward according to the three different scenarios developed for the LCA and MCDM analyses, due to the high impact of the fibre production processes. More investigations are needed to balance and optimize the coupling of the fibre material and the solid medium to obtain high thermal performance and low impacts

Web-based randomised controlled trials in orthodontics

Randomised controlled trials (RCT) are considered the best source of scientific evidence--the gold standard--when evaluating the efficacy of orthodontic treatments. Frequently, RCT are planned as multicentre trials, with the intention of increasing statistical power and raising the precision of outcome estimates. The management of large-scale RCT, however, requires even more thorough organisation than conventional RCT. Indeed, the need for high accuracy and standardisation in data collection, research aids, secretarial skills, staff and patient training, and organisational meetings, make these studies time-consuming, expensive and, in general, relatively complex to carry out well. A website was developed to support a large scale-orthodontic RCT which aimed to evaluate the efficacy of a functional appliance(www.ortodonzia.unina.it). Websites such as this can increase the quality of data collection, simplify the randomisation process, speed up data collection, and improve trial monitoring. Web-based RCT have the potential to help globalise orthodontic research and also increase our rate of acquisition of evidence in orthodontics

Combination of heterogeneous and homogeneous grouping to achieve better reading and math scores

This report described the process used, for an elementary school with a student population of approximately 587 students, to investigate the existing reading and math programs offered to students. The preliminary research indicated a need for an extended staff development program, and the implementation of advanced methodologies. The conclusions of the project, as a whole, provided data which emphasizes the need for growth in reading and math pedagogy awareness with the district of Glassboro. Purposed preliminary investigation strategies included; (a) interviews with reading and math teachers, regular homeroom teachers, and teachers in other academic disciplines; (b) a review of documents such as district reading and math results, course of study, individual student reading and math folders, and grade point averages in the reading and math classes; (c) observations of reading and math instruction; and (d) a continued review of the research and literature on grouping for instruction and related fields of study. In response to the information acquired during the preliminary investigation an intervention strategy may be proposed to improve, modify, or expand the grouping methods, reading, and math programs offered at Thomas E. Bowe School

Bear Stearns Ralph Cioffi e-mail message to Adam Kugler

Series of emails from 3/25/2007 to 6/1/2007