91 resultados para Lead recycling


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Atomic absorption spectroscopy of the ionic liquid 1-ethyl-3-methylimidazolium ethanoate ([emim](2)[O2CMe]), prepared according to International Patent WO 96/18459, showed it to contain large amounts of lead impurity: (ca. 0.5 M): [emim](2)[Pb(O2CMe)(4)] was isolated and shown crystallographically to contain the first known example of a monomeric, homoleptic pentacoordinate lead(ii) carboxylate complex, with a stereochemically active lone-pair.

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The dose received by anatomical structures which are apparently shielded by lead blocks during a course of megavoltage radiotherapy may not be negligible. The dose has three main components; there is that due to radiation transmitted through the shielding block, that due to radiation scattered within the patient and that due to radiation scattered prior to reaching the patient and so circumventing the shield. A calculation method which separates the three components has been investigated and the results have been compared with measurements in a wide range of test situations for both cobalt-60 and 6 MV photon beams. The method of calculation predicts the dose behind the shielding block with acceptable accuracy in all the conditions investigated.

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Purpose: Environmental turbulence including rapid changes in technology and markets has resulted in the need for new approaches to performance measurement and benchmarking. There is a need for studies that attempt to measure and benchmark upstream, leading or developmental aspects of organizations. Therefore, the aim of this paper is twofold. The first is to conduct an in-depth case analysis of lead performance measurement and benchmarking leading to the further development of a conceptual model derived from the extant literature and initial survey data. The second is to outline future research agendas that could further develop the framework and the subject area.

Design/methodology/approach: A multiple case analysis involving repeated in-depth interviews with managers in organisational areas of upstream influence in the case organisations.

Findings: It was found that the effect of external drivers for lead performance measurement and benchmarking was mediated by organisational context factors such as level of progression in business improvement methods. Moreover, the legitimation of the business improvement methods used for this purpose, although typical, had been extended beyond their original purpose with the development of bespoke sets of lead measures.

Practical implications: Examples of methods and lead measures are given that can be used by organizations in developing a programme of lead performance measurement and benchmarking.

Originality/value: There is a paucity of in-depth studies relating to the theory and practice of lead performance measurement and benchmarking in organisations.

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Incinerator bottom ash (IBA) is a residual produced from incinerating municipal solid waste. In the past, IBA presented a big waste disposal problem; however, various recycling approaches have been adopted in recent years to mitigate this problem, as well as to provide a useful alternative to using primary aggregate resources. The use of IBA as an alternative to conventional aggregates in different civil engineering construction applications helps to conserve premium grade aggregate supplies; however, when IBA is in contact with water in the field, as a consequence of precipitation events or changes in water table, elements, such as salts and heavy metals, may be released to the soil and ground water. In this work, IBA waste was mixed with limestone aggregate to produce a blend with acceptable mechanical properties and minimum environmental risks for use as road foundation. The study focused on evaluating potential environmental impacts of some constituents, including sulphate, chloride, sodium, copper, zinc and lead in IBA blends using a lysimeter as a large scale leaching tool. Moreover, a specific scenario simulating field conditions was adopted in the lysimeter to assess the potential impact of changing conditions, such as IBA content in the blend, liquid to solid ratio (L/S) and pH value, on long-term release of heavy metals and salts. Then, numerical modelling was used to predict the release of the aforementioned constituents from IBA based on initial measurement of intrinsic material properties and the kinetic desorption process concept. Experimental results showed that zinc and lead were released in very low concentrations but sodium and sulphate were in high concentrations. The control limestone only blend also demonstrated low release concentrations of constituents in comparison to IBA blends, where constituent concentrations increased with increase in IBA content. Experimental results were compared with numerical results obtained using a non-equilibrium desorption model. Good agreement was found between the two sets of data. 

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Venom of the Gila Monster (Heloderma suspectum) has proven to be an unlikely source of lead compounds (exendins) for the development of new injectable peptide therapeutics for the treatment of Type 2 diabetes. However, no systematic searches for new classes of bioactive peptides in lizard venom have appeared until recently. Here we describe the discovery of a new class of peptides – the helokinestatins – from H. suspectum venom, their structural characterisation and that of their biosynthetic precursors from cloned cDNA. In addition, we have subjected members of the family to preliminary pharmacological characterisation. Helokinestatins 1–6 are a family of proline-rich peptides containing 10–15 amino acid residues terminating in a common -Pro-Arg.OH motif. They are encoded in tandem within two virtually identical biosynthetic precursors of 177 and 178 amino acid residues, differing by only a single Pro residue. Each precursor also encodes a single copy of a C-type natriuretic peptide located at the C-terminus. Synthetic replicates of all helokinestatins were shown to be devoid of any direct action on the smooth muscle of rat tail artery but were found to be potent inhibitors of bradykinin-induced relaxation in this preparation in a manner that is suggestive of a non-competitive mechanism. Helokinestatin-3 (VPPPPLQMPLIPR) and helokinestatin-5 (VPPPLQMPLIPR) were found to be most potent in this respect causing almost complete inhibition of bradykinin-induced relaxation. Helokinestatins and BPPs may have a shared evolutionary history but the former do not inhibit ACE. The bradykinin inhibitory potential of helokinestatins may be exploited in the local control of chronic inflammation.

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In an effort to contribute to greater understanding of norms and identity in the theory of planned behaviour, an extended model was used to predict residential kerbside recycling, with self-identity, personal norms, neighbourhood identification, and injunctive and descriptive social norms as additional predictors. Data from a field study (N = 527) using questionnaire measures of predictor variables and an observational measure of recycling behaviour supported the theory. Intentions predicted behaviour, while attitudes, perceived control, and the personal norm predicted intention to recycle. The interaction between neighbourhood identification and injunctive social norms in turn predicted personal norms. Self-identity and the descriptive social norm significantly added to the original theory in predicting intentions as well as behaviour directly. A replication survey on the self-reported recycling behaviours of a random residential sample (N = 264) supported the model obtained previously. These findings offer a useful extension of the theory of planned behaviour and some practicable suggestions for pro-recycling interventions. It may be productive to appeal to self-identity by making people feel like recyclers, and to stimulate both injunctive and descriptive norms in the neighbourhood.

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Two studies were carried out in England to investigate the role of essentialist national group definitions in determining the effect of national identification on prejudice towards immigrants, and asylum seekers in particular. It was expected that the relationship between national identification and prejudice would depend on the degree to which participants endorse an essentialist (`ethnic') definition of their nationality. Consistent with this, Study 1 (N=154) found that national identification is associated with negativity towards asylum seekers only among individuals who endorse an essentialist conception of the group, and shows no significant association with prejudice among those who reject such a conception. Study 2 (N=219) used a longitudinal design conducted over 6 weeks, allowing cross-lagged analysis of causality between essentialism, identification, and behavioural intentions towards asylum seekers. A causal effect of essentialism on willingness to support a group acting against asylum seekers was observed, with no significant causal effect in the reverse direction. The reverse causal direction was observed in the case of support for a group seeking to support asylum seekers, with intended behaviours determining essentialism. The results are discussed in terms of the importance of group definitions in the study of in-group affiliations and prejudice.

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Electron tunnelling spectroscopy, developed to extract superconductive metals the electron-phonon spectral density, $\alpha^2F(\nu)$, is found to be a powerful tool also for extracting a more realistic pseudopotential from such metals. The pseudopotential so extracted has a range of surprising but physically reasonable properties and regenerates $\alpha^2F(\nu)$ accurately. Free from most of its long-standing uncertainties, thie pseudopotential may be useful in a number of active fields.