Influence of Ionic Strength and pH on the Limitation of Latex Microsphere Deposition Sites on Iron-oxide Coated Sand by Humic Acid

This paper advances findings of Yang et al. 2010 and reports on how slight changes in pH or Ionic strength can significantly alter particle behaviour in porous media, when humic acids have been deposited beforehand. .

A study of the relationship between process conditions and mechanical strength of mineralized red algae in the preparation of a marine-derived bone void filler

Bone void fillers that can enhance biological function to augment skeletal repair have significant therapeutic potential in bone replacement surgery. This work focuses on the development of a unique microporous (0.5-10 mu m) marine-derived calcium phosphate bioceramic granule. It was prepared fro Corallina officinalis, a mineralized red alga, using a novel manufacturing process. This involved thermal processing, followed by a low pressure-temperature chemical synthesis reaction. The study found that the ability to maintain the unique algal morphology was dependent on the thermal processing conditions. This study investigates the effect of thermal heat treatment on the physiochemical properties of the alga. Thermogravimetric analysis was used to monitor its thermal decomposition. The resultant thermograms indicated the presence of a residual organic phase at temperatures below 500 degrees C and an irreversible solid-state phase transition from mg-rich-calcite to calcium oxide at temperatures over 850 degrees C. Algae and synthetic calcite were evaluated following heat treatment in an air-circulating furance at temperatures ranging from 400 to 800 degrees C. The highest levels of mass loss occurred between 400-500 degrees C and 700-800 degrees C, which were attributed to the organic and carbonate decomposition respectively. The changes in mechanical strength were quantified using a simple mechanical test, which measured the bulk compressive strength of the algae. The mechanical test used may provide a useful evaluation of the compressive properties of similar bone void fillers that are in granular form. The study concluded that soak temperatures in the range of 600 to 700 degrees C provided the optimum physiochemical properties as a precursor to conversion to hydroxyapatite (HA). At these temperatures, a partial phase transition to calcium oxide occurred and the original skeletal morphology of the alga remained intact.

Strength and permeation properties as an indicator of durability of concrete

Durability of concrete is a great concern to all designers, owners and users of reinforced concrete structures. As a result, more restrictive regulations are being introduced in various Codes of Practice dealing with the design of these structures. Attempts are being made by various researchers to develop performance based specification. For this to be successful standard non destructive tests are required which will be used to assess the durability of concretes. In parallel with this approach, a research team in Queen’s University Belfast, U. K., investigated the effect of different mix parameters on workability, strength and various permeation properties. Furthermore, durability parameters such as freeze-thaw salt scaling resistance and carbonation depth were also investigated. The research was part funded by the Department of Environment, Transport and the Regions (DETR). This paper reports of the findings from this study. The results from this investigation showed that some of the non destructive tests used were reasonably well correlated with carbonation and freeze-thaw salt scaling resistance of CEM I concrete. If the mix parameters such as aggregate-cement ratio or water-cement ratio are known, better correlation can be obtained. Further investigation is required varying other mix parameters including various aggregates, admixtures and air entrainments before the result can be used for developing mix design methods for durable concretes. Also long term site tests are required to validate the results obtained from the accelerated laboratory tests used to study the carbonation resistance and freeze-thaw salt scaling resistance.

Investigation of Ultimate Strength of Deck Slabs in Steel-Concrete Bridges

In the last 50 years, many bridges have been built as composite structures with decks of reinforced concrete that are supported by longitudinal steel beams. The presence of the longitudinal steel beams and the unloaded area of concrete slab cause the loaded deck slabs to be restrained against lateral expansion. As a result, a compressive membrane thrust is developed. In experimental tests, the authors built a series of one-third scale steel-concrete composite bridge models with several varying structural parameters, including concrete compressive strength, reinforcement percentage, and the size of steel supporting beams. After comparing the results of different models, the influence of these structural parameters on the amount of compressive membrane action in the deck slab was evaluated. Furthermore, the improvement of an existing theoretical model provided accurate predictions for the loading-carrying capacities.

Ultimate compressive strength of cold-formed steel angle struts loaded through a single bolt

This paper presents design recommendations for the strength of cold-formed steel angle structs. The work was part funded by the Carnegie Trust and is co-authored by academics from Hong-Kong University. The work has led to a collaboration with the University of Malaya, attempting to predict the strength using artificial neural networks.

Overcoming Customer Dependency - A Case Study of Small Consumer Food Producers in Northern Ireland

Dependency on a small number of customer puts intense pressure on suppliers' profit margin and, in slow growing markets, limits their ability to grow. using stragtegic benchmarking information, a group of Northern Ireland consumer food producer are shown, depsite slow market growth and higher than averge customer dependency, to have increased market share while maintaining aboe vergate proitability. examination of the business strategic and develoment activites of the consumer food firms,and comparble information for other small food prodcuers in Ireland, suggests and emphasiss on cost-reduction and new prodcut development. A comparision of the productivity and prodcut range of the consuer food firms provides evidence of the success of these strategic. This suggests that even a relatively weak market situations, charactrised by dependency on a small number of customers, can be over come by effective and appropriate business strategy.

How trophic interaction strength depends on traits

A key problem in community ecology is to understand how individual-level traits give rise to population-level trophic interactions. Here, we propose a synthetic framework based on ecological considerations to address this question systematically. We derive a general functional form for the dependence of trophic interaction coefficients on trophically relevant quantitative traits of consumers and resources. The derived expression encompasses-and thus allows a unified comparison of-several functional forms previously proposed in the literature. Furthermore, we show how a community's, potentially low-dimensional, effective trophic niche space is related to its higher-dimensional phenotypic trait space. In this manner, we give ecological meaning to the notion of the "dimensionality of trophic niche space." Our framework implies a method for directly measuring this dimensionality. We suggest a procedure for estimating the relevant parameters from empirical data and for verifying that such data matches the assumptions underlying our derivation. © Springer Science+Business Media B.V. 2009.


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Interfacial shear strength and tensile properties of injection-molded, short- and long-glass fiber-reinforced polyamide 6,6 composites

Injection-molded short- and long-glass fiber/polyamide 6,6 composites were subjected to tensile tests. To measure the effectiveness of the fibers in reinforcing the composites, a computational approach was employed to compute the fiber– matrix ISS, orientation factor, reinforcement efficiency, tensile-, and fiber length-related properties. Although the LFCs showed great improvement in fiber characteristics compared to the SFCs, enhancement in tensile properties was small, which is believed to be due to the larger fiber diameter. Kelly–Tyson model provides good approximation for the computation of ISS and tensile-related properties.