Hamiltonian Relative Equilibria with Continuous Isotropy

In symmetric Hamiltonian systems, relative equilibria usually arise in continuous families. The geometry of these families in the setting of free actions of the symmetry group is well-understood. Here we consider the question for non-free actions. Some results are already known in this direction, and we use the so called bundle equations to provide a systematic treatment of this question which both consolidates the known results, extending the scope of the results to deal with non-compact symmetry groups, as well as producing new results. Specifically we address questions about the stability, persistence and bifurcations of these relative equilibria

Distributed semantic networks and CLIPS

Semantic networks of frames are commonly used as a method of reasoning in many problems. In most of these applications the semantic network exists as a single entity in a single process environment. Advances in workstation hardware provide support for more sophisticated applications involving multiple processes, interacting in a distributed environment. In these applications the semantic network may well be distributed over several concurrently executing tasks. This paper describes the design and implementation of a frame based, distributed semantic network in which frames are accessed both through C Language Integrated Production System (CLIPS) expert systems and procedural C++ language programs. The application area is a knowledge based, cooperative decision making model utilizing both rule based and procedural experts

Investigation of strength recovery of recycled heat treated glass fibres through chemical treatments

The strength loss of thermally treated glass fibre (GF) at elevated temperature is well reported in literature. This phenomenon even occurs at short period of time such as 25 minutes. In the recycling technologies for composites, GFs are usually recovered by degradation of polymeric matrix with thermal and/or chemical treatments. Therefore thermal effect on the strength of GF is a significant factor when restricting the possibilities of recycling this material for a second life. This study reports on the strength of thermally treated commercial GF after acid treatment and silanization of the fibre surface to achieve a proper combination of treatments which may provide us with the ability to recover the mechanical properties of the heat treated GFs. It is thought that silane coupling agents can directly increase and recover the strength of GFs. Two factors associated with this recovery are the possibility of the sizing repairing the damage on the surface of the heat treated GFs and the reduction of the fibre-fibre friction in the bundle through lubricating effect. GF samples were heat treated at 4500C for 25 minutes and coated with silanes, applying different combinations of hydrochloric acid (HCl) and the two silanes used in this study, γ-Aminopropyltrimethoxy Silane (APS) and γ- Methacryloxypropyltrimethoxy Silane (MPS); these fibres were characterized by single fibre testing for strength. The results obtained demonstrated that the fibre strength improves slightly after combination of HCl and MPS treatment, and has a negative effect when the combination of HCl and APS was used. The surface deposition of silane on the surface of the fibre is also discussed using a Scanning Electron Microscope (SEM)

THE LATIN AMERICAN ORGANIC COFFEE INDUSTRY: U.S. MARKET INROADS

Certified organic coffee is a minuscule but important portion of coffee production and trade and is the fastest growing sector in sales revenue. Organic coffee has its roots in sustainable crop production and economic development policy. Latin America has become the center of the organic coffee movement, representing a change from the old market structure of the coffee trade. The U.S. organic coffee market has experienced extraordinary growth in the past five years because of an increase in consumer social and ecological awareness. Latin America supplies most of the organic coffee entering the United States, where Mexico, Colombia, and Guatemala are the main exporters. Colombian and Guatemalan organic coffee, according to the survey, receive the highest price premiums because of the perception of superior quality. Surveyed importers and roasters in the United States believe that the organic coffee market will continue to grow at least for the next 10 years. Oversupply, economies of size, and reduced price premiums are seen as the biggest problems to be faced by organic coffee producers in the coming years.Agribusiness, Crop Production/Industries, Industrial Organization,

A case of the Rodriguez Villegas conjecture

Let L be a number field and let E be any subgroup of the units O_L^* of L. If rank(E) = 1, Lehmer's conjecture predicts that the height of any non-torsion element of E is bounded below by an absolute positive constant. If rank(E) = rank(O_L^*), Zimmert proved a lower bound on the regulator of E which grows exponentially with [L:Q]. Fernando Rodriguez Villegas made a conjecture in 2002 that "interpolates" between these two extremes of rank. Here we prove a high-rank case of this conjecture. Namely, it holds if L contains a subfield K for which [L:K] >> [K:Q] and E contains the kernel of the norm map from O_L^* to O_K^*

Regeneration of thermally recycled glass fibre for cost-effective composite recycling : Performance of composites based on PP and Recovered glass fibre

Due to economic and technical reasons, no recycling process for glass fibre composites has been commercialized on a large scale. Thermal recycling processes are promising in terms of potential for commercialization but the reinforcement potential of thermally recycled fibres is too low for the application in composites. In the present study, glass fibres were exposed to elevated temperatures prior to composite processing to imitate a thermal recycling process. The exposure of the fibres to elevated temperatures prior to composite processing caused a significant reduction of the mechanical properties of the composites. The heat treated fibres were regenerated with a post treatment. The regeneration of the glass fibres recovered the mechanical properties of the composites almost completely. Thus, this study shows that composites based on thermally recycled glass fibres have the potential to compete with composites based on ‘new’ glass fibres

Measurement of Nanoparticles Release during Drilling of Polymer Nanocomposites

Nanomaterials are one of the promising technologies of this century. The Project on Emerging Nanotechnologies [1] reports more than 1600 consumer products based on nanotechnology that are currently on the market and advantages link to the reinforcement of polymeric materials using nano-fillers are not to demonstrate anymore. However, the concerns about safety and its consumer perception can slow down the acceptance of nanocomposites. Indeed, during its life-cycle, a nanotechnology-based product can release nano-sized particles exposing workers, consumers and environment and the risk involved in the use and disposal of such particles is not well known. The current legislation concerning chemicals and environment protection doesn’t explicitly cover nanomaterials and changes undergone by nanoparticles during the products’ life cycle. Also, the possible physio-chemical changes that the nanoparticles may undergo during its life cycle are unknown. Industries need a standard method to evaluate nanoparticles release during products’ life cycle in order to improve the knowledge in nanomaterials risk assessment and the legislation, and to inform customers about the safety of nanomaterials and nanoproducts. This work aims to propose a replicable method in order to assess the release of nanoparticles during the machining of nanocomposites in a controlled environment. For this purpose, a new experimental set-up was implemented and issues observed in previous methods (background noise due to uncontrolled ambient environment and the process itself, unrepeatable machining parameters) were solved. A characterisation and validation of the chamber used is presented in this paper. Also, preliminary testing on drilling of polymer-based nanocomposites (Polyamide-6/Glass Fibre reinforced with nano-SiO2) manufactured by extrusion and injection moulding were achieved

Functionalisation of Ti6Al4V and hydroxyapatite surfaces with combined peptides based on KKLPDA and EEEEEEEE peptides

Surface modifications are usually performed on titanium alloys to improve osteo-integration and surface bioactivity. Modifications such as alkaline and acid etching, or coating with bioactive materials such as hydroxyapatite, have previously been demonstrated. The aim of this work is to develop a peptide with combined titanium oxide and hydroxyapatite binders in order to achieve a biomimetic hydroxyapatite coating on titanium surfaces. The technology would also be applicable for the functionalisation of titanium and hydroxyapatite surfaces for selective protein adsorption, conjugation of antimicrobial peptides, and adsorption of specialised drugs for drug delivery. In this work, functionalisation of Ti6Al4V and hydroxyapatite surfaces was achieved using combined titanium-hydroxyapatite (Ti-Hap) peptides based on titanium binder (RKLPDA) and hydroxyapatite binder (EEEEEEEE) peptides. Homogeneous peptide coatings on Ti6Al4V surfaces were obtained after surface chemical treatments with a 30 wt % aqueous solution of H2O2 for 24 and 48 hours. The treated titanium surfaces presented an average roughness of Sa=197 nm (24 h) and Sa=128 nm (48 h); an untreated mirror polished sample exhibited an Sa of 13 nm. The advancing water contact angle of the titanium oxide layer after 1 hour of exposure to 30 wt % aqueous solution of H2O2 was around 65°, decreasing gradually with time until it reached 35° after a 48 hour exposure, suggesting that the surface hydrophilicity increased over etching time. The presence of a lysine (L) amino acid in the sequence of the titanium binder resulted in fluorescence intensity roughly 16 % higher compared with the arginine (R) amino acid analogue and therefore the lysine containing titanium binder was used in this work. The Ti-Hap peptide KKLPDAEEEEEEEE (Ti-Hap1) was not adsorbed by the treated Ti6Al4V surfaces and therefore was modified. The modifications involved the inclusion of a glycine spacer between the binding terminals (Ti-Hap2) and the addition of a second titanium binder (KKLPDA) (Ti-Hap3 and Ti-Hap4). The Ti-Hap peptide aptamer which exhibited the strongest intensity after the titanium dip coating was KKLPDAKKLPDAEEEEEEEE (Ti-Hap4). On the other hand, hydroxyapatite surfaces, exhibiting an average roughness of Sa=1.42 µm, showed a higher fluorescence for all peptides compared with titanium surfaces