The synthesis of biodegradable polymers using aluminium alkoxide initiators

Alkyl aluminium alkoxides have been used as initiators for the ring opening polymerisation of ε-caprolactone and δ-valerolactone. The effect of the reaction solvent on the kinetics of the polymerisation of ε-caprolactone has been studied. The rate of polymerisation was found to be faster in solvents of lower polarity and donor nature such as toluene. In general solvents of higher polarity resulted in a decreased rate of polymerisation. However solvents such as THF or DMF with a lone pair of electrons capable of forming a complex with the aluminium centre slowed the polymerisation further. The size of the monomer also proved to be an important factor in the kinetics of the reaction. The six membered ring, δ-valerolactone has less ring strain than the seven membered ring ε-caprolactone and thus the polymerisation of δ-valerolactone is slower than the corresponding polymerisation of ε-caprolactone. Both the alkoxide and alkyl group structures have an effect on the polymerisation. In general bulkier alkoxide groups provide greater steric hindrance around the active site at the beginning of the reaction. This causes an induction or a build up period that is related to the both the steric hindrance and also the electronic effects provided by the alkoxide group. The alkyl group structure has an effect throughout the polymerisation because it remains adjacent to the active centre. The number of alkoxide groups on the aluminium centre is also important, using a dialkoxide as an initiator yields polymers with molecular weights approximately half that of the corresponding reactions using a mono alkoxide. Transesterification reactions have also been found to occur after most of the monomer has been consumed. These transesterification reactions are exaggerated as temperature increases. A method of producing tri-block co-polymers has also been developed. A di-hydroxy functional pre-polymer, PHBV, was reacted with an aluminium alkyl to form a di-alkoxide macroinitiator which was subsequently used as an initiator for the polymerisation of ε-caprolactone to form an ABA type tri-block co-polymer. The molecular weight and other properties were predictable from the initial monomer/initiator ratios.

Corporate social responsibility in China:impact of regulations, market orientation and ownership structure

Purpose – This paper aims to report on a study that contributes to the understanding of the determinants of corporate social responsibility (CSR) in the largest emerging market, namely China. Design/methodology/approach – The approach is a survey of 600 hotels that resulted in 143 returned responses from top managers. Findings – Market orientation is the most significant predicator of CSR followed by government regulations. In contrast, ownership structure is found to have little effect. Originality/value – Previous research on CSR focuses on its nature and impact on business performance, and is carried out mainly in developed countries. This research contributes to one's understanding of the determinants of CSR in emerging markets like China. © 2007, Emerald Group Publishing Limited

Approaches to sharing knowledge in group problem structuring

Problem-structuring techniques are an integral aspect of 'Soft-OR'. SSM, SAST, Strategic Choice, and JOURNEY Making, all depend for their success on a group developing a shared view of a problem through some form of explicit modelling. The negotiated problem structure becomes the basis for problem resolution. Implicit to this process is an assumption that members of the group share and build their knowledge about the problem domain. This paper explores the extent to which this assumption is reasonable. The research is based on detailed records from the use of JOURNEY Making, where it has used special purpose Group Support software to aid the group problem structuring. This software continuously tracks the contributions of each member of the group and thus the extent to which they appear to be 'connecting' and augmenting their own knowledge with that of other members of the group. Software records of problem resolution in real organisational settings are used to explore the sharing of knowledge among senior managers. These explorations suggest a typology of knowledge sharing. The implications of this typology for problem structuring and an agenda for future research are considered.

Use of ultrasonic agitation in iron group alloy electrodepositions

The effects of ultrasonic agitation on deposition from two iron group alloy plating solutions, nickel-cobalt and bright nickel-iron, have been studied. Comparison has been made with deposits plated from the same solutions using controlled air agitation. The ultrasonic equipment employed had a fixed frequency of 13 KHz but the power output from each transducer was variable up to a maximum of 350 watts. The effects of air and ultrasonic agitation on hardness, ductility, tensile strength, composition, structure, surface topography, limiting current density, cathode current efficiency and macro-throwing power were determined. Transmission and scanning electron microscopy, electron-probe microanalysis and atomic absorption spectrophotometry have been employed to study the nickel alloy deposits produced. The results obtained show that the use of Ultrasonics increased significantly the hardness of both alloy deposits and altered their composition by decreasing the cobalt and iron contents from nickel-cobalt and nickeliron solutions respectively. The ductility of coatings improved but the tensile strength did not change very much. Ultrasonic agitation gave larger grained deposits than air and they seemed to have a lower stress. Dull cobalt-nickel deposits had a similar pyramidal surface topography regardless of the type of agitation but the bright appearance of the nickel-iron was destroyed by ultrasonic agitation; an unusual ribbed pattern was produced. The use of ultrasonic agitation permitted approximately a twofold increase in the plating current density at which sound deposits could be achieved but there was only a slight increase in cathode current efficiency. Macro-throwing power of the solutions was increased slightly by the use of ultrasonic agitation. ultrasonic agitation is an expensive means of agitating plating Solutions and would be worthwhile only if significant improvements in properties could be achieved. The simultaneous improvement in hardness and ductility is a novel feature that should have useful engineering applications.

The black middle class: middle class Afro-Caribbeans: a racial fraction of the British middle class or a class fraction of a racial group

This research examines the relationship between 'race' and class in Britain. This is achieved by considering how these two concepts articulate in the overall structuring of class relationships in a society which is typified by the incorporatation of black labour into a majority white society, This relationship is examined through an investigation of those black workers who occupy a position in the objectively defined middle class. The basic theme underlying this research is that 'race, in the form of structural racism, plays a significant role at two levels. Firstly, it serves to structure the class position of black labour in Britain. Secondly, it serves to determine the type of race, class and political consciousness generated by black labour. The study was carried out in the London area. Occupation was used as an indicator of 'objective' class position when selecting respondents to be included in the two survey populations required for the research. A 'network' approach was used to actually locate the respondents. In-depth interviews were carried out with all the respondents. The study concludes that the concepts of 'race' and class are not independent of each other in the overall structuring of class relationships between black and white labour. It is argued that the inter-relationship identified between these two concepts serves to highlight the fact that the structural position of black labour, the type of consciousness generated and the type of decisions taken by those who took part in the research are to a large extent a result of the structural constraints deriving from the effects of structural racism in Britain.

Structure and function in primary open angle glaucoma

The study utilised a Normal group, an Ocular Hypertensive (OHT) group and a Primary Open Angle Glaucoma (POAG) group to investigate two aspects. Firstly, the within- and between-visit variability for stereometric measurements of the optic nerve head (ONH) using the Heidelberg Retina Tomograph (HRT); retinal nerve fibre layer (RNFL) thickness using the HRT and using optical coherence tomography with the Optical Coherence Tomography Scanner (OCT); the visual field using white-on-white (W-W), short-wavelength (SWAP) and Frequency Doubling perimetry (FDT); and retinal haemodynamics using the Heidelberg Retinal Flowmeter (HRF). Secondly, the association demonstrated between some of the derived variables. The within- and between-visit variability for stereometric measurements of the entire ONH and the between-visit variability for sectoral measurements were similar for Normals and OHTs but greater for POAGs. The within-visit variability of the visual field pointwise parameters for SWAP were greater than for W-W and FDT particularly with increase in eccentricity and for the OHT group. The between-visit variability increased with increase in defect depth for the POAG group, across all types of perimetry. The MS was greater, the MD and PSD smaller and the examination duration shorter in FDT compared to W-W and SWAP across all groups. The within-visit variability was less than the between-visit variability for the OCT circumferential and sector RNFL thickness using the 1.5R, 2.0R and the fixed 1.73mm circular scan radii, across the three groups. The variability increased with decrease in the RNFL thickness, and was least for the 2.0R scan radius.

Strategic planning in a decentralised industrial group : a process-action study

The research was carried out within a major public company. It sought to implement an approach to strategic planning which accounted for organisational values as well as employing a holistic value-free analysis of the firm and its environment. To this end, an 'ecological' model of the firm was formulated. A series of value-free strategic policies for its development were generated. These policies were validated by the company's top-management.They compared favourably with their own planning outcomes. The approach appeared to be diagnostically strong but lacked sufficient depth in the context of finding realistic corrective measures. However, feedback from the company showed it to be a useful complementary process to conventional procedures, in providing an explicitly different perspective. The research empirically evaluated the company's value-systems and their influence on strategy. It introduced the idea of an organisational 'self-concept' pre-determining the acceptability of various strategies.The values and the "self-concept' of the company were identified and validated, They appeared to have considerable influence on strategy. In addition, tho company's planning process within the decentralised structure was shown to be sub-optimal. This resulted from the variety of value systems maintained by different parts of the organisation. Proposals attempting to redress this situation were ofJered and several accepted. The study was postured as process-action research and the chosen perspective could be succinctly described as a 'worm's-eye view', akin to that of many real planners operating at some distance from the decision-making body. In this way, the normal strategic functionings of the firm and any changes resulting from the researcher's intervention were observed and recorded. Recurrent difficulties of the planning process resulting from the decentralised structure were identified. The overall procedure suggested as a result of the research aimed to increase the viabiIity of planning and the efficiency of the process. It is considered to be flexible enough to be applicable in a broader context.

Synthesis of arbitrary group delay responses with all-pass optical cavities structures

We propose a systematic method for the synthesis of arbitrary group delay responses by using all-pass structures of coupled optical cavities. Optimum structure parameters design, in terms of filter order and accuracy, are obtained.

Designing in a group:how does knowing each other influence design projects

This paper presents a study of engineering design groups that seeks to explain how knowing other participants can influence processes and outcomes in design projects. Research in this paper contributes a framework to approach understanding how interpersonal relationships influence group processes and outcomes. This acknowledges that engineering design is achieved through individuals working in groups. First a temporal perspective is introduced to understand how individuals (through interpersonal relationships), group processes and outcomes influence each other; secondly identity is presented as a theme to focus on how knowing other participants identity influences group processes and outcomes. Within this framework it is recognised that engineering design has different levels of complexity of which two aspects are considered: design type and design setting. These aspects place different demands on a project group and its members and this structure provides an opportunity for cross case analysis to generalise findings.

An investigation into enterprise structure and ERP implementations:a contribution to praxis

This professional doctoral research reports on the relationship between Enterprise Systems, specifically Enterprise Resource Planning Systems, and enterprise structures. It offers insights and guidance to practitioners on factors for consideration in the implementation of ERP systems in organisations operating in modern enterprise structures. It reports on reflective ethnographic action research conducted in a number of companies from a diverse range of industries covering supply chains for both goods and services. The primary contribution is in highlighting areas in which clients, practitioners and ERP software vendors can bring a greater awareness of internet era enterprise structures and business requirements into the ERP arena. The concepts and insights have been explored in a focus group setting, comprised of practitioners from the enterprise systems implementation and consulting fraternity and revealed limitations and constraints in the implementation of enterprise systems. However, it also showed that current systems do not have the full capabilities required to support, in use, modern era enterprise structures, as required by practitioners and decision makers.

Synthesis of arbitrary group delay responses with all-pass optical cavities structures

We propose a systematic method for the synthesis of arbitrary group delay responses by using allpass structures of coupled optical cavities. Optimum structure parameters design, in terms of filter order and accuracy, are obtained. © 2012 OSA.

Structure and physical properties of [µ-Tris(1,4-bis(tetrazol-1-yl)butane-N4,N4‘')iron(II)] Bis(hexafluorophosphate), a new Fe(II) spin-crossover compound with a three-dimensional threefold interlocked crystal lattice

[μ-Tris(1,4-bis(tetrazol-1-yl)butane-N4,N4‘)iron(II)] bis(hexafluorophosphate), [Fe(btzb)3](PF6)2, crystallizes in a three-dimensional 3-fold interlocked structure featuring a sharp two-step spin-crossover behavior. The spin conversion takes place between 164 and 182 K showing a discontinuity at about T1/2 = 174 K and a hysteresis of about 4 K between T1/2 and the low-spin state. The spin transition has been independently followed by magnetic susceptibility measurements, 57Fe-Mössbauer spectroscopy, and variable temperature far and midrange FTIR spectroscopy. The title compound crystallizes in the trigonal space group P30¯(No. 147) with a unit cell content of one formula unit plus a small amount of disordered solvent. The lattice parameters were determined by X-ray diffraction at several temperatures between 100 and 300 K. Complete crystal structures were resolved for 9 of these temperatures between 100 (only low spin, LS) and 300 K (only high spin, HS), Z = 1 [Fe(btzb)3](PF  6)2:  300 K (HS), a = 11.258(6) Å, c = 8.948(6) Å, V = 982.2(10) Å3; 100 K (LS), a = 10.989(3) Å, c = 8.702(2) Å, V = 910.1(4) Å3. The molecular structure consists of octahedral coordinated iron(II) centers bridged by six N4,N4‘ coordinating bis(tetrazole) ligands to form three 3-dimensional networks. Each of these three networks is symmetry related and interpenetrates each other within a unit cell to form the interlocked structure. The Fe−N bond lengths change between 1.993(1) Å at 100 K in the LS state and 2.193(2) Å at 300 K in the HS state. The nearest Fe separation is along the c-axis and identical with the lattice parameter c.

Crystal structure and magnetic behaviour of a five-coordinate iron(III) complex of pyridoxal-4-methylthiosemicarbazone

The crystal structure and magnetic properties of a penta-coordinate iron(III) complex of pyridoxal-4-methylthiosemicarbazone, [Fe(Hmthpy)Cl](CHCHSO), are reported. The synthesised ligand and the metal complex were characterised by spectroscopic methods (H NMR, IR, and mass spectroscopy), elemental analysis, and single crystal X-ray diffraction. The complex crystallises as dark brown microcrystals. The crystal data determined at 100(1) K revealed a triclinic system, space group P over(1, ¯) (Z = 2). The ONSCl geometry around the iron(III) atom is intermediate between trigonal bipyramidal and square pyramidal (t = 0.40). The temperature dependence of the magnetic susceptibility (5-300 K) is consistent with a high spin Fe(III) ion (S = 5/2) exhibiting zero-field splitting. Interpretation of these data yielded: D = 0.34(1) cm and g = 2.078(3). © 2007 Elsevier B.V. All rights reserved.

Controllable group delay in a θ-shaped microfiber resonator with coupled-resonator-induced transparency

The control of Light velocity is theoretically and experimentally demonstrated in a θ-shaped microfiber resonator with coupled-resonator-induced transparency. By adjusting the structure parameters, group delays from -60ps to 200ps are achieved in the all-fiber resonator.