12 resultados para CHAIN GROWTH
em Aston University Research Archive
Resumo:
The "living" and/or controlled cationic ring-opening bulk copolymerization of oxetane (Ox) with tetrahydropyran (THP) (cyclic ether with no homopolymerizability) at 35°C was examined using ethoxymethyl-1 -oxoniacyclohexane hexafluoroantimonate (EMOA) and (BF3 · CH3OH)THP as fast and slow initiator, respectively, yielding living and nonliving polymers with pseudoperiodic sequences (i.e., each pentamethylene oxide fragment inserted into the polymer is flanked by two trimethylene oxide fragments). Good control over number-average molecular weight (Mn up to 150000 g mol-1) with molecular weight distribution (MWD ∼ 1.4-1, 5) broader than predicted by the Poison distribution (MWDs > 1 +1/DPn) was attained using EMOA as initiating system, i.e., C 2H5OCH2Cl with 1.1 equiv of AgSbF6 as a stable catalyst and 1.1 equiv of 2,6-di-tert-butylpyridine used as a non-nucleophilic proton trap. With (BF3 · CH 3OH)THP, a drift of the linear dependence M n(GPC) vs Mn(theory) to lower molecular weight was observed together with the production of cyclic oligomers, ∼3-5% of the Ox consumed in THP against ∼30% in dichloromethane. Structural and kinetics studies highlighted a mechanism of chains growth where the rate of mutual conversion between "strain ACE species" (chain terminated by a tertiary 1-oxoniacyclobutane ion, Al) and "strain-free ACE species" (chain terminated by a tertiary 1-oxoniacyclohexane ion, Tl) depends on the rate at which Ox converts the stable species T1 (kind of "dormant" species) into a living "propagating" center A1 (i.e., k aapp[Ox]). The role of the THP solvent associated with the suspension of irreversible and reversible transfer reactions to polymer, when the polymerization is initiated with EMOA, was predicted by our kinetic considerations. The activation -deactivation pseudoequilibrium coefficient (Qt) was then calculated in a pure theoretical basis. From the measured apparent rate constant of Ox (kOxapp) and THP (kTHPapp = ka(endo)app) consumption, Qt and reactivity ratio (kp/kd, k a(endo)/ka(exo), and ks/ka(endo) were calculated, which then allow the determination of the transition rate constant of elementary step reactions that governs the increase of Mu with conversion. © 2009 American Chemical Society.
Resumo:
Reactive oxygen species (ROS) and ceramide are each partly responsible for the signal transduction of a variety of extracellular agents. Furthermore, the application of synthetic, short-chain ceramides mimics the cellular responses to these extracellular agents. However, the significance of ROS involvement in ceramide signaling pathways is poorly understood. Here we describe that the (cellular responses to C2-/C6-ceramide of growth arrest in U937 monocytes and apoptosis in Jurkat T-cells are preceded by a rise in mitochondrial peroxide production. In Jurkat T-cells, this is associated with a large time- and dose-dependent loss of cellular glutathione. However, in U937 monocytes, glutathione loss is transient. Differences in the magnitude and kinetics of this alteration in cellular redox state associate with discrete outcomes, namely growth arrest or apoptosis. © 2002 Elsevier Science (USA). All rights reserved.
Resumo:
Innovation events – the introduction of new products or processes – represent the end of a process of knowledge sourcing and transformation. They also represent the beginning of a process of exploitation which may result in an improvement in the performance of the innovating business. This recursive process of knowledge sourcing, transformation and exploitation comprises the innovation value chain. Modelling the innovation value chain for a large group of manufacturing firms in Ireland and Northern Ireland highlights the drivers of innovation, productivity and firm growth. In terms of knowledge sourcing,we find strong complementarity between horizontal, forwards, backwards, public and internal knowledge sourcing activities. Each of these forms of knowledge sourcing also makes a positive contribution to innovation in both products and processes although public knowledge sources have only an indirect effect on innovation outputs. In the exploitation phase, innovation in both products and processes contribute positively tocompany growth, with product innovation having a short-term ‘disruption’ effect on labour productivity. Modelling the complete innovation value chain highlights the structure and complexity of the process of translating knowledge into business value and emphasises the role of skills, capital investment and firms’ other resources in the value creation process.
Resumo:
We present the first innovation value chain analysis for a representative sample of new technology based firms (NTBFs) in the UK. This involves determining which factors lead to the usage of different knowledge sources and the relationships that exist between those sources of knowledge; the effect that each knowledge source has on innovative activity; and how innovation outputs affect the performance of NTBFs. We find that internal and external knowledge sources are complementary for NTBFs, and that supply chain linkages have both a direct and indirect effect on innovation. NTBFs’ skill resources matter throughout the innovation value chain, being positively associated with external knowledge linkages and innovation success, and also having a direct effect on growth independent of the effect on innovation. Exporting matters for performance, but not through any effect on innovation.
Resumo:
Innovation events - the introduction of new products or processes - represent the end of a process of knowledge sourcing and transformation. They also represent the beginning of a process of exploitation which may result in an improvement in the performance of the innovating business. This recursive process of knowledge sourcing, transformation and exploitation we call the innovation value chain. Modelling the innovation value chain for a large group of manufacturing firms in Ireland and Northern Ireland highlights the drivers of innovation, productivity and firm growth. In terms of knowledge sourcing, we find strong complementarity between horizontal, forwards, backwards, public and internal knowledge sourcing activities. Each of these forms of knowledge sourcing also makes a positive contribution to innovation in both products and processes although public knowledge sources have only an indirect effect on innovation outputs. In the exploitation phase, innovation in both products and processes contribute positively to company growth, with product innovation having a short-term ‘disruption’ effect on labour productivity. Modelling the complete innovation value chain highlights the structure and complexity of the process of translating knowledge into business value and emphasises the role of skills, capital investment and firms’ other resources in the value creation process.
Resumo:
Industrial development, accompanying human population growth, has had a major role in creating the situation where bio-diverse materials and services essential for sustaining business are under threat. A major contributory factor to biodiversity decline comes from the cumulative impacts of extended supply chain business operations. However, within Corporate Responsibility (CR) reporting impacts on biodiversity due to supply chain operations have not traditionally been given equal weighting with other environmental issues. This paper investigates the extent of CR reporting in managing and publicising company biodiversity supply chain issues by reviewing a cross-sector sample of publicly available CR reports. The report contents were examined for suggestions of industrial sectorial trends in the level of biodiversity consideration. The reporting of environmental management system use within company supply chain management is assessed in the samples and is considered as a mechanism for responsible supplier partnership working.
Resumo:
Innovation is central to the survival and growth of firms, and ultimately to the health of the economies of which they are part. A clear understanding both of the processes by which firms perform innovation and the benefits which flow from innovation in terms of productivity and growth is therefore essential. This paper demonstrates the use of a conceptual framework and modeling tool, the innovation value chain (IVC), and shows how the IVC approach helps to highlight strengths and weaknesses in the innovation performance of a key group of firms-new technology-based firms. The value of the IVC is demonstrated in showing the key interrelationships in the whole process of innovation from sourcing knowledge through product and process innovation to performance in terms of the growth and productivity outcomes of different types of innovation. The use of the IVC highlights key complementarities, such as that between internal R&D, external R&D, and other external sources of knowledge. Other important relationships are also highlighted. Skill resources matter throughout the IVC, being positively associated with external knowledge linkages and innovation success, and also having a direct influence on growth independent of the effect on innovation. A key benefit of the IVC approach is therefore its ability to highlight the roles of different factors at various stages of the knowledge-innovation-performance nexus, and to show their indirect as well as direct impact. This in turn permits both managerial and policy implications to be drawn. © 2012 Product Development & Management Association.
Resumo:
We explore the causal links between service firms' knowledge investments, their innovation outputs and business growth based on a bespoke survey of around 1100 UK service businesses. We combine the activity based approach of the innovation value chain with firms' external links at each stage of the innovation process. This introduces the concept of 'encoding' relationships through which learning improves the effectiveness of firms' innovation processes. Our econometric results emphasise the importance of external openness in the initial, exploratory phase of the innovation process and the significance of internal openness (e.g. team working) in later stages of the process. In-house design capacity is strongly linked to a firm's ability to absorb external knowledge for innovation. Links to customers are important in the exploratory stage of the innovation process, but encoding linkages with private and public research organisations are more important in developing innovation outputs. Business growth is related directly to both the extent of firms' service innovation as well as the diversity of innovation, reflecting marketing, strategic and business process change.
Resumo:
This thesis involves the secondary data of 1806 innovative manufacturing firms derived from the database of 2nd Taiwanese Innovation Survey. Three topics are researched. The first topic investigates the innovation value chain (IVC) in Taiwanese manufacturing firms. Previous IVC studies are all done in developed countries such as UK, Ireland, Northern Ireland and Switzerland, and it leaves the gap of those non-developed countries. The result shows the overall knowledge sourcing pattern of Taiwanese manufacturing firms presenting a complementary relationship which is consistent to the previous IVC studies. The main innovation input is still derived from internal R&D which suggests more utilisation of external knowledge may boost innovation outcome. Product innovation does enhance firm growth while process innovation reduces a firm’s productivity. The second topic uses the lens of IVC to investigate the difference of the innovation process from knowledge linkages to value added between high-tech and low- tech sectors. The findings indicate (1) there are significant differences in the IVC between high- and low-tech sectors, however these are defined; (2) how you define ‘sector’ matters i.e. the nature of the high-tech and low-tech differences varies depending on whether the technology definition is carried out at the industry or firm level; and (3) the high uncertainty of innovation cause the difficulty to predict firm performance especially for those firms with high intensity of innovation. The third topic investigates the innovation-exporting relationship and explores the determinants of export performance. Product innovation enhances export performance once a firm enters international markets while process innovation affects negatively on a firm’s likelihood of being an exporter. Furthermore, IP protection is found to affect directly export performance positively.
Resumo:
This paper reports on an innovative UK-based ‘Supply Chain Learning’ (SCL) initiative to encourage the corporate sector to consider supplier diversity in respect of ethnic minority businesses. This follows academic and policy interest in programmes to empower ethnic minority enterprises to achieve breakout to mainstream markets and business growth. The first phase of the initiative, entitled Supplier Development East Midlands (SDEM) is examined. By adopting an inter-organisational action learning approach, some of the key attributes of the programme are delineated, focusing on the recurrent action-reflection cycle taking place in a learning group comprising SDEM, LPOs (Large Purchasing Organisations) and small EMSs (Ethnic Minority Suppliers).
Resumo:
Using the resource-based view framework, we investigate the link between multiunit franchising (MUF) and performance on four key challenges in franchise chain management: growth, uniformity, local responsiveness, and system-wide adaptation. Our findings support the assertion that system growth is positively related to MUF rate within a system, in particular in relation to geographic expansion. Interestingly, while uniformity does not seem to be related to MUF rate, we find marginal support for an inverted u-shaped relationship between system-wide adaptation and MUF rate. Furthermore, the data suggest that local responsiveness and MUF rate are related in a u-shaped function.
Resumo:
The number of research papers linking sustainability with supply chain management is increasing around the world. The purpose of this paper is to analyse how the publications in Brazil are considering the relationship between sustainability and supply chain management. The methodology applied consists in five major steps: (1) selection of databases and journals, (2) selection of the papers, (3) reading of papers' abstracts to select only papers that are related to business and sustainability, (4) qualitative and quantitative analysis of the selected papers' abstracts to define the main dimension of sustainability and sustainability aspect, and finally, (5) an evaluation of experts' responses to a questionnaire in the field of sustainability and supply chain in Brazil. The literature review was conducted in 120 Brazilian academic journals in which 124 papers were identified as being published in relation to sustainability, business management and companies, from 2008 until 2013. When considering the traditional Triple Bottom Line approach, the results of the analysis show that sustainability research in Brazil is focusing on the environmental dimension and SCM research is focusing on the economic dimension. Additional inputs are provided by integrating the governance dimension in the analysis to underline which actions and policies are discussed in Brazilian literature at a corporate level. The consultation of experts in the field of sustainability in Brazil was aimed at understanding better the results of the conducted literature review. One of the main conclusions is that there are large opportunities to increase publications about sustainability and SCM in the country.