Anion induced displacement studies in naphthalene diimide containing interpenetrated and interlocked structures

This article describes investigations into the development of supramolecular systems capable of sensing anions through either displacement type assays or molecular motion. An electron deficient naphthalene diimide thread and electron rich isophthalamide naphthohydroquinone macrocycle was shown to form a coloured pseudorotaxane assembly. Investigations into the ability of such interpenetrated systems to sense anions colorimetrically were undertaken. Anion complexation to the isophthalamide group of the macrocycle causes displacement of the naphthodiimide thread resulting in the loss of colour. The enhanced mechanically bonded binding strength between the naphthodiimide axle and the naphthohydroquinone groups of the macrocycle wheel in the corresponding rotaxane structure however, was found to negate the anion induced displacement process.

Sulfate anion templation of macrocycles, capsules, interpenetrated and interlocked structures

This review examines the potential of anions, in particular sulfate, to template the formation of complex molecular architectures. Until recently, sulfate has been largely overlooked in this area and the examples described herein demonstrate this anion’s versatility in templating the formation of a diverse range of molecular systems including macrocycles, helixes, molecular capsules, interpenetrated and interlocked assemblies such as catenanes. In addition sulfate has been shown to template the formation of interpenetrated structures on a range of solid surfaces including gold, polystyrene beads and silicate nanoparticles, highlighting the potential of this anion in the fabrication of functional sensory devices exhibiting highly selective binding behaviour.

A comparison of alternative bankruptcy prediction models

Early models of bankruptcy prediction employed financial ratios drawn from pre-bankruptcy financial statements and performed well both in-sample and out-of-sample. Since then there has been an ongoing effort in the literature to develop models with even greater predictive performance. A significant innovation in the literature was the introduction into bankruptcy prediction models of capital market data such as excess stock returns and stock return volatility, along with the application of the Black–Scholes–Merton option-pricing model. In this note, we test five key bankruptcy models from the literature using an upto- date data set and find that they each contain unique information regarding the probability of bankruptcy but that their performance varies over time. We build a new model comprising key variables from each of the five models and add a new variable that proxies for the degree of diversification within the firm. The degree of diversification is shown to be negatively associated with the risk of bankruptcy. This more general model outperforms the existing models in a variety of in-sample and out-of-sample tests.

Vibration characteristics of concrete-steel composite floor structures

This paper discusses the vibration characteristics of a concrete-steel composite multi-panel floor structure; the use of these structures is becoming more common. These structures have many desirable properties but are prone to excessive and complex vibration, which is not currently well understood. Existing design codes and practice guides provide generic advice or simple techniques that cannot address the complex vibration in these types of low-frequency structures. The results of this study show the potential for an adverse dynamic response from higher and multi-modal excitation influenced by human-induced pattern loading, structural geometry, and activity frequency. Higher harmonics of the load frequency are able to excite higher modes in the composite floor structure in addition to its fundamental mode. The analytical techniques used in this paper can supplement the current limited code and practice guide provisions for mitigating the impact of human-induced vibrations in these floor structures.

A review of optimization techniques used in the design of fibre composite structures for civil engineering applications

Fibre composite structures have become the most attractive candidate for civil engineering applications. Fibre reinforced plastic polymer (FRP) composite materials have been used in the rehabilitation and replacement of the old degrading traditional structures or build new structures. However, the lack of design standards for civil infrastructure limits their structural applications. The majority of the existing applications have been designed based on the research and guidelines provided by the fibre composite manufacturers or based on the designer’s experience. It has been a tendency that the final structure is generally over-designed. This paper provides a review on the available studies related to the design optimization of fibre composite structures used in civil engineering such as; plate, beam, box beam, sandwich panel, bridge girder, and bridge deck. Various optimization methods are presented and compared. In addition, the importance of using the appropriate optimization technique is discussed. An improved methodology, which considering experimental testing, numerical modelling, and design constrains, is proposed in the paper for design optimization of composite structures.