Tunable kinetics of nanoaluminum and microaluminum powders reacting with water to produce hydrogen

This paper reports on the kinetics and reaction processes of 40‐nm and 1‐μm aluminum powders with water to produce hydrogen at atmospheric pressure. This reaction produces aluminum hydroxide with irregular morphologies as by‐products. It was found that the nucleation and growth of the aluminum hydroxides affect the kinetics of the reaction and thus the hydrogen production. The heat release in isothermal microcalorimetry and hydrogen production in a nonisothermal batch reactor were used to determine the rate‐determining steps of the reaction mechanism and the corresponding activation energies. Model and model‐free methods have been implemented to describe the reaction sequence between aluminum particle and water while the phase of newly produced aluminum hydroxide in the system plays an important role. The reaction of nanoaluminum particles and water, being more sensitive to temperature, goes to completion to produce bayerite, Al (OH)₃ at 30°C, and boehmite, AlOOH at 50°C, whereas the microaluminum particles do not react completely and produce only bayerite at 30°C and also low‐amount boehmite at 50°C. Nevertheless, these processes exhibit two distinct and sequential stages: a kinetically controlled stage with the apparent activation energy (E_a) of 100 to 110 kJ/mol, where nucleation and growth are limited by the chemical reactions on the surface of aluminum, and a diffusion controlled stage with E_a of 44 kJ/mol for the 40‐nm Al/water reaction and 86 kJ/mol for the 1‐μm Al/water reaction, where growth is limited by the mass diffusion through the aluminum hydroxide by‐products. The separation of these two stages is more obvious under isothermal conditions. For nonisothermal conditions, two stages are overlapped, and the one with a lower E_a dominates.     

Seasonal variations in natural organic matter and its impact on coagulation in water treatment

In the past decade, a number of UK and US water utilities have been experiencing operational difficulties connected with the increased dissolved organic carbon (DOC) levels during the autumn and winter periods. This has been observed as an increase in the production of disinfection-by-products (DBP), and a greater coagulant demand. Resin adsorption techniques were used to fractionate raw water and investigate the variation in surface charge and coagulant-humic interactions over a 36-month period. A change in the natural organic matter (NOM) composition throughout the year was observed, with the fulvic acid fraction (FAF) increasing from 36% in September to 61% in November. However, a reduction in treatment performance is not simply due to an increase in DOC concentrations (from 4.3 to 14.5 mg L-1), but also a change in the charge density of the NOM. It was found that hydrophilic NOM fractions possess negligible charge density (<0.06 meq g-1DOC), and it is the hydrophobic NOM fractions, FAF in particular, that exert the greater dominance on coagulation control. The hydrophilic NOM fractions are less amenable to removal through conventional coagulation with metal salts, and are therefore likely to indicate the DOC residual remaining after treatment. Understanding the seasonal changes in NOM composition and character and their reactivity with coagulants should lead to a better optimisation of the coagulation process and a more consistent water quality.     

Austerity and reform to affordable housing policy

The recession has created significant challenges for the government with regard to providing affordable housing. Even during the UK’s housing boom the supply of housing failed to keep pace with demand. Therefore, increasing housing supply and improving affordability in a recessionary period will require the government to innovatively utilise their limited resources. Following the Comprehensive Spending Review in 2010 severe cuts to the housing budget were made and radical reforms to housing and planning policy have been proposed by the coalition government. The paper briefly discusses the UK housing market and affordable housing policy and practice recently employed in England. Subsequently a discussion of the coalition government’s recent reforms to housing and planning policy, concerning affordable housing, is presented.     

Involving users in the design and usability evaluation of a clinical decision support system

AIM: To design and evaluate a clinical decision support system (CDSS) to support cardiovascular risk prevention in type 2 diabetes. METHODS: A preliminary requirements specification and three prototype CDSS interface designs were developed. Seven patients and seven clinicians conducted 'usability tests' on five different task scenarios with the CDSS prototypes to test its effectiveness, efficiency and 'user-friendliness'. Structured, qualitative questions explored their preferences for the different designs and overall impressions of clinical usefulness. RESULTS: Patients and clinicians were enthusiastic about the CDSS and used it confidently after a short learning period. Some patients had difficulty interpreting clinical data, but most were keen to see the CDSS used to help them understand their diabetes, provided a clinician explained their results. Clinicians' main concern was that the CDSS would increase consultation times. Changes suggested by users were incorporated into the final interface design. CONCLUSION: We have successfully incorporated patients' and clinicians' views into the design of a CDSS, but it was an arduous process.     

Ischemia-induced object-recognition deficits in rats are attenuated by hippocampal ablation before or soon after ischemia.

The literature on the role of the hippocampus in object-recognition contains a paradox: Transient forebrain ischemia (ISC) produces hippocampal damage and severe deficits on the delayed nonmatching-to-sample (DNMS) task, yet hippocampal ablation (ABL) produces milder deficits. Experiment 1 confirmed that pretrained rats display severe DNMS deficits following ISC, but not ABL. Ischemia produced loss of CA1 neurons. but no obvious extrahippocampal damage. In Experiments 2 and 3, ISC rats from Experiment 1 received ABL. and ABL rats received ISC: neither treatment affected DNMS performance. In Experiment 4, rats that received ISC followed 1 hr later by ABL displayed only mild deficits. It is hypothesized that ISC-induced DNMS deficits are due to extrahippocampal damage produced by pathogenic processes that involve the hippocampus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CEGB ASSESSMENT PROCEDURE FOR DEFECTS IN PLANT OPERATING IN THE CREEP RANGE

In recent years considerable progress has been made in research work addressing the behaviour of defects at elevated temperature. Developments have been made both in structural assessment techniques and in methods for analysing representative materials data. On the basis of these developments a procedure has been produced within the CEGB for the assessment of defects in plant operating in the creep range under loadings for which creep rather than creep-fatigue is the dominant failure mechanism. This paper describes the CEGB procedure. Calculations are required for three events: the time for overall structural failure by continuum damage mechanisms; the time for incubation prior to crack extension; and the time for subsequent growth to a maximum tolerable defect size. Methods are presented for calculating these times and for obtaining the materials data required to perform the calculations.