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Showing papers by "Dublin City University published in 1994"


Journal ArticleDOI
TL;DR: In this paper, thin films of transparent conducting aluminum-doped ZnO have been deposited using a sol-gel process and the dependence of electrical characteristics upon aluminum concentration in the films and upon post-deposition heat treatment in vacuum was examined.

350 citations


Journal ArticleDOI
TL;DR: Fungi can accumulate metal and radionuclide species by physico-chemical and biological mechanisms including extracellular binding by metabolites and biopolymers, binding to specific polypeptides and metabolism-dependent accumulation.
Abstract: Fungi can accumulate metal and radionuclide species by physico-chemical and biological mechanisms including extracellular binding by metabolites and biopolymers, binding to specific polypeptides and metabolism-dependent accumulation. Biosorptive processes appear to have the most potential for environmental biotechnology. ‘Biosorption’ consists of accumulation by predominatly metabolism-independent interactions, such as adsorptive or ion-exchange processes: the biosorptive capacity of the biomass can be manipulated by a range of physical and chemical treatments. Immobilized biomass retains biosorptive properties and possesses a number of advantages for process applications. Native or immobilized biomass can be used in fixed-bed, air-lift or fluidized bed bioreactors; biosorbed metal/radionuclide species can be removed for reclamation and the biomass regenerated by simple chemical treatments.

147 citations


Journal ArticleDOI
TL;DR: The reaction kinetics of the two F. hepatica cathepsin L proteinases on a variety of peptide substrates revealed that the two enzymes differ in their substrate specificity.
Abstract: A 29.5-kDa cysteine proteinase was purified from medium in which mature Fasciola hepatica parasites were maintained. The N-terminal sequence (14 residues) of the purified protein is similar to known cathepsin L proteinases, including a 27-kDa cathepsin L proteinase, also secreted by this parasite, which had been isolated previously in our laboratory [Smith, A. M., Dowd, A. J., Mc Gonigle, S., Keegan, P. S., Brennan, G., Trudgett, A. & Dalton, J. P. (1993) Mol. Biochem. Parasitol. 62, 1–8]. The N-terminal sequences of the 29.5-kDa and 27-kDa cathepsin L proteinases differ only in residue number seven (arginine and proline, respectively). Immunoblot studies, using antiserum that reacts with both cathepsin L proteinases, rule out the possibility of both enzymes arising from a higher molecular sized parent molecule. The reaction kinetics of the two F. hepatica cathepsin L proteinases on a variety of peptide substrates revealed that the two enzymes differ in their substrate specificity. Five peptide substrates that are cleaved with high affinity by the 29.5-kDa cathepsin L isolated in this study are not cleaved by the previously purified 27-kDa cathepsin L. The protein-modifying reagent, tetranitromethane, affected the 29.5-kDa cathepsin L proteinase only, causing inactivation of the enzyme and changing its migration in polyacrylamide gel electrophoresis. Our studies suggest that the two F. hepatica cysteine proteinases represent two distinct subclasses within the cathepsin L class.

100 citations


Journal ArticleDOI
TL;DR: Exponential bounds �’[queue≥b]≤ϕeγb are found for queues whose increments are described by Markov Additive Processes by application of maximal inequalities to exponential martingales for such processes.
Abstract: Exponential bounds P(queue > b) < ~e -'rb are found for queues whose increments are described by Markov Additive Processes. This is done by application of maximal inequalities to exponential martingales for such processes. Through a thermodynamic approach the constant ,~ is shown to be the decay rate for an asymptotic lower bound for the queue length distribution. The class of arrival processes considered includes a wide variety of Markovian multiplexer models, and a general treatment of these is given, along with that of Markov modulated arrivals. Particular attention is paid to the calculation of the prefactor ~y. The problem of finding the queue length distribution in a queue with non- independent arrivals has attracted much attention recently due to applications in the design of multiplexers for the emergent asynchronous transfer mode (ATM) of data transmission in integrated services digital networks (ISDN). From the tech- nological point of view it is required to guarantee sufficiently good quality of service: loss probabilities must be appropriately small and waiting times sufficiently short. The problem is resistant to simple exact treatment due to the nature of the arrival process. It is a superposition of sources which are typically bursty, in the sense that their activity is highly correlated into bursts rather than occurring indepen- dently at different times; and periodic (when viewed at the short time scales of the multiplexer output) either due to their origin (e.g. periodic sampling of voice traf- fic) or their occupation of periodic slots allocated for transmission. The goal of ana- lysis is to provide mechanisms for design and performance prediction, and algorithms for allocation of resources during the operation of such devices. It is desirable that the results of such analysis be conservative in the sense that they should not overestimate the capacity of resources.

95 citations


Book
01 Dec 1994
TL;DR: Foundations of fuzzy logic fuzzy modelling fuzzy logic controllers (FLCs) - design issues analysis of fyzzy control systems fuzzy logic software design and implementation fuzzy logic hardwareDesign and implementation applications.
Abstract: Foundations of fuzzy logic fuzzy modelling fuzzy logic controllers (FLCs) - design issues analysis of fyzzy control systems fuzzy logic software design and implementation fuzzy logic hardware design and implementation applications.

85 citations


Journal ArticleDOI
TL;DR: In this paper, a tetrameric calixarene bearing hydroxamic acid functional groups was synthesized and supported on octadecylsilica and XAD-4 resin.

80 citations


Journal ArticleDOI
TL;DR: Synchrotron-radiation core-level photoemission spectra indicate evidence of sulfur bonding to both gallium and arsenic at room temperature, but that the relative magnitude of these bonding interactions depends on the Ga/As ratio of the clean surface.
Abstract: A study of the adsorption of sulfur on the GaAs(100) surface after in situ thermal desorption of a protective As capping layer is presented. The sulfur flux was generated by the decomposition of silver sulfide in an UHV-compatible electrochemical cell. Use of As-capped samples provided a means to study the interaction of sulfur with both the c(2×8) and (4×1) surface reconstructions. Scanning-tunneling-microscopy images of the sulfur-covered surface indicated the formation of disordered surface layers which display a diffuse (1×1) low-energy-electron-diffraction pattern. This (1×1) phase is attributed to the symmetry of the bulk structure visible through the disordered surface overlayer, caused by the adsorbed sulfur breaking the surface dimer bonds. Synchrotron-radiation core-level photoemission spectra indicate evidence of sulfur bonding to both gallium and arsenic at room temperature, but that the relative magnitude of these bonding interactions depends on the Ga/As ratio of the clean surface. Sulfur 2p photoemission spectra from the annealed surfaces show that sulfur diffuses into the topmost atomic layers as well as bonding to the surface. Annealing the sulfur-covered surface above 400 °C results in the formation of a (2×1) low-energy-electron-diffraction pattern with a dimer-row structure clearly visible in scanning-tunneling-microscopy images. Our results would suggest that the adsorption of sulfur on the c(2×8) clean surface results in dimer rows consisting of both arsenic and sulfur dimers, while only sulfur dimers are observed after adsorption on the (4×1) surface. The degree to which the clean surface band bending is altered on these respective surfaces appears to be related to the precise chemical composition of the dimer rows.

79 citations


Journal ArticleDOI
TL;DR: In this article, an intrinsic evanescent wave fiber optic sensor for oxygen is reported based on the quenching of fluorescence from a ruthenium complex trapped in the cage-like structure of a sol-gel-derived porous film on a de-clad section of multimode optical fibre.
Abstract: An intrinsic evanescent wave fibre optic sensor for oxygen is reported. The sensor is based on the quenching of fluorescence from a ruthenium complex trapped in the cage-like structure of a sol-gel-derived porous film on a de-clad section of multimode optical fibre. The sensor exhibits excellent performance using blue LED excitation and silicon photodiode detection, and establishes the viability of low-cost portable sensor devices based on the sol-gel process. Gas phase measurement data over the range 0-100% oxygen exhibit high signal-to-noise ratio ( approximately 150), good repeatability and short response time (<5 s).

73 citations


Book
31 Aug 1994
TL;DR: Part 1 Manager's Guide to Implementing A Quality System and part 2 Software Engineer's Guide To Best Projects.
Abstract: Part 1 Manager's Guide To Implementing A Quality System 1. Defining Software Quality Why Bother with Quality? Quality: What is It? 2. Managing A Quality Company DT> Dedication to Customer Satisfaction Emphasis on Continuous Improvement Treating Suppliers as Business Partners Communication and Teamwork Empowering Employees Commitment by Top Management Total Quality Management 3. Implementing A Quality System Towards a Quality System Initiate a Quality Program Plan a Quality Program Implement the Cultural Program Implement the Technical Program D> Review and Evaluate 4. Quality Certification What is ISO 9000 Certification? Reasons for ISO 9000 Certification What ISO Certification Involved ISO 9000 Certification around the World Alternative to ISO9000 Part 2 Software Engineer's Guide To Best Projects 5. Applying Best Practice To Projects Software Engineering Definition Quality Principles Management Principles D> Engineering Principles Software Engineering Practices 6. Life Cycle Activities Overview Life Cycle Approaches User Requirements Software Requirements Architectural Design DD> Production Transfer Maintenance 7. Supporting Activities Overview Project Management Configuration Management Verification Software Quality Assurance TRONG>8. Organization Level Activities Process Management Procurement Training Management Responsibility

70 citations


Book
01 Jan 1994
TL;DR: Denby as discussed by the authors argues that sentimentalism is central to the culture of late eighteenth-century France and explores how the language and forms of sentimental narratives were adopted and exploited by political and social writers.
Abstract: In this discerning study of sentimental discourse of the late eighteenth century, David J. Denby sheds new light on Enlightenment thought and sensibility. He reveals how sentimental sub-literature reflects the social attitudes of the emerging bourgeoisie, and how its formal structures are reflected in contemporary theories concerning the nature of society, morality, and politics. Denby explores how the language and forms of sentimental narratives were adopted and exploited by political and social writers, and how sentimentalism provided a theme of continuity underlying the dominant sense of change brought about by the Revolution. In this interdisciplinary book Denby argues that sentimentalism is central to the culture of late eighteenth-century France. Texts discussed include works by Rousseau and de Stael.

69 citations


Journal ArticleDOI
TL;DR: This experiment represents the first step in photoionization studies of this fundamental atomic system in which the motion of the three electrons in the field of the nucleus is so highly correlated.
Abstract: Using a dual laser plasma technique we have measured for the first time the photoabsorption spectrum of atomic lithium at energies corresponding to the simultaneous excitation of both 1s electrons. We have observed the main triply excited 1${\mathit{s}}^{2}$2s${(}^{2}$S)\ensuremath{\rightarrow}2${\mathit{s}}^{2}$p${(}^{2}$P) transition with Fano parameters ${\mathit{E}}_{0}$=142.32\ifmmode\pm\else\textpm\fi{}0.05 eV \ensuremath{\Gamma}=0.20\ifmmode\pm\else\textpm\fi{}0.04 eV, and q=-2.2\ifmmode\pm\else\textpm\fi{}0.6. Our experiment represents the first step in photoionization studies of this fundamental atomic system in which the motion of the three electrons in the field of the nucleus is so highly correlated.

Journal ArticleDOI
TL;DR: Using bis-imidates and of bis-succinimides to modify free amino groups of commercial horseradish peroxidase under mild conditions of pH and temperature helps preserve the carbohydrate side chains for subsequent reaction or immobilization.

Journal ArticleDOI
TL;DR: This report presents the deduced amino acid sequence of a novel cathepsin L proteinase from Schistosoma mansoni, and describes cathePSin L-like activity in extracts of adult schistosomes.

Journal ArticleDOI
TL;DR: A comparative study of the aminopeptidase activity in each extract revealed that the enzymes have similar specificities and kinetics, a near‐neutral pH optima of 7.2 and are moderately thermophilic.
Abstract: . Using fluorogenic substrates and polyacrylamide gels we detected in cell-free extracts of Plasmodium falciparum, Plasmodium chabaudi chabaudi and Plasmodium berghei only a single aminopeptidase. A comparative study of the aminopeptidase activity in each extract revealed that the enzymes have similar specificities and kinetics, a near-neutral pH optima of 7.2 and are moderately thermophilic. Each has an apparent molecular weight of 80,000 ± 10,000, determined by high performance liquid chromatography on a calibrated SW500 column. Whilst the P. c. chabaudi and P. berghei activity co-migrate in native polyacrylamide gels, that of P. falciparum migrates more slowly. The three enzymes can be selectively inhibited by ortho-phenanthroline and are thus metallo-aminopeptidases; however, in contrast to other aminopeptidases the metal co-factor does not appear to be Zn2+.

Journal Article
TL;DR: HRP is a calcium-containing, extensively glycosylated, stable haemoprotein possessing four disulphide bridges and weighing 44 kDa that is very widely used as an indicator in immunoassays, non-isotopic DNA probes, cytochemistry, bi-enzyme systems and biosensors due to its stability, high catalytic rates, ease of conjugation to other molecules and wide choice of assays of activity.
Abstract: HRP is a calcium-containing, extensively glycosylated, stable haemoprotein possessing four disulphide bridges and weighing 44 kDa. It is an oxidoreductase which can use a wide variety of hydrogen donors to reduce hydrogen peroxide. This gives rise to a range of colorimetric, fluorimetric, chemiluminescent and electrochemical assays for HRP activity. HRP is very widely used as an indicator in immunoassays, non-isotopic DNA probes, cytochemistry, bi-enzyme systems and biosensors. This is owing to its stability, high catalytic rates, ease of conjugation to other molecules and wide choice of assays of activity.

Journal ArticleDOI
A. Fitzsimons1, Pascal Hols1, J. Jore1, Rj. Leer1, M. O'Connell1, Jean Delcour1 
TL;DR: A recombinant alpha-amylolytic L. plantarum strain with the starch-degrading ability displayed by Lactobacillus amylovorus would seem to have considerable potential as a silage inoculant for crops such as alfalfa, in which water-soluble carbohydrate levels are frequently low but starch is present as an alternative carbohydrate source.
Abstract: An amylolytic Lactobacillus plantarum silage strain with the starch-degrading ability displayed by Lactobacillus amylovorus was developed. An active fragment of the gene coding for alpha-amylase production in L. amylovorus was cloned and integrated into the chromosome of the competitive inoculant strain L. plantarum Lp80 at the cbh locus. The alpha-amylase gene fragment was also introduced into L. plantarum Lp80 on an autoreplicative plasmid. Both constructions were also performed in the laboratory strain L. plantarum NCIB8826. All four recombinant strains secreted levels of amylase ranging from 23 to 69 U/liter, compared with 47 U/liter for L. amylovorus. Secretion levels were higher in L. plantarum NCIB8826 than in L. plantarum Lp80 derivatives and were higher in recombinant strains containing autoreplicative plasmids than in the corresponding integrants. The L. plantarum Lp80 derivative containing the L. amylovorus alpha-amylase gene fragment integrated into the host chromosome secreted alpha-amylase to a level comparable to that of L. amylovorus and nas stable over 50 generations of growth under nonselective conditions. It grew to a higher cell density than either the parent strain or L. amylovorus in MRS medium containing a mixture of starch and glucose as the fermentable carbohydrate source. This recombinant alpha-amylolytic L. plantarum strain would therefore seem to have considerable potential as a silage inoculant for crops such as alfalfa, in which water-soluble carbohydrate levels are frequently low but starch is present as an alternative carbohydrate source.

Journal ArticleDOI
TL;DR: In this article, a method for the determination of metals in vitamin tablets and a pond water sample is presented, using a sample stacking technique in order to obtain better detection limits and greater sensitivity.

Journal ArticleDOI
TL;DR: In this paper, a multilaser multichannel spectrometer system was developed that allows a wide range of investigations of the interaction of extreme-ultraviolet (EUV) photons with matter in the form of free atoms or ions, e.g., in gases or plasmas or bound as in solids.
Abstract: A new multilaser multichannel spectrometer system has been developed that allows a wide range of investigations of the interaction of extreme-ultraviolet (EUV) photons with matter in the form of free atoms or ions, e.g., in gases or plasmas or bound as in solids. The EUV photons are generated by a laser-produced plasma. Applications to the study of photoabsorption by thin foils, gases, and ground- and excited-state atoms and ions are described. The design and performance of a collimated, quasi-monochromatic, intense source of EUV radiation based on the combination of a laser-produced plasma with a EUV multilayer mirror is also reported.

Journal ArticleDOI
TL;DR: In this paper, a simple low-cost technique for fabricating reagent-mediated fiber-optic chemical sensors (optrodes) is described and the performance of a range of such sensors is reported.
Abstract: A simple, low-cost technique for fabricating reagent-mediated fibre-optic chemical sensors (optrodes) is described and the performance of a range of such sensors is reported. The technique is based on coating an unclad portion of an optical fibre with a microporous glass film prepared by the sol-gel process. Although tip- and side-coating are both possible with this technique, the latter, which employs evanescent wave interactions, offers particular advantages in terms of sensor performance, control of sensitivity and quality of coating. The sol-gel-derived film is used to provide a robust support matrix in which analyte-sensitive dyes are entrapped and into which smaller analyte molecules may diffuse. The benefits of this sol-gel approach to sensor fabrication are illustrated by results from a range of sensors for pH, ammonia and oxygen based on both evanescent wave absorption and evanescent wave excitation of fluorescence.

Journal ArticleDOI
TL;DR: The surface reactivity of highly dispersed (85%) palladium cluster catalysts supported on γ-alumina (1.5 wt% loading) had been probed using the molecular beam scattering technique as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this paper, two evanescent wave fiber optic sensors for oxygen are reported: one intensity-based and the other based on phase fluorimetry, which employ the quenching by oxygen of the fluorescence from a ruthenium complex trapped in the cagelike structure of a sol-gel-derived porous film on a declad section of multimode optical fiber.
Abstract: Two evanescent wave fiber optic sensors for oxygen are reported: one intensity based and the other based on phase fluorimetry. Both sensors employ the quenching by oxygen of the fluorescence from a ruthenium complex trapped in the cagelike structure of a sol-gel-derived porous film on a declad section of multimode optical fiber. The sensors exhibit excellent performance using excitation from new high brightness blue LEDs and establish the viability of low-cost portable sensor devices based on the 501-gel process.

Journal ArticleDOI
TL;DR: In this paper, freeze-dired, oven-dried, and nonmetabolizing live Rhizopus arrhizus biomass were tested for their capacity to adsorb the test ions, Sr2+, cd2+, and Cu2+, over the pH range 4-6.

Journal ArticleDOI
TL;DR: Refex as discussed by the authors is a low-resistance polyvinyl acetate that contains a very large loading of KCl (1:1 w/w KCI/PVA).
Abstract: The performance and properties of a new low-resistance material, Refex, suitable for use in reference electrode junctions is described. The material is a solid polyvinyl acetate that contains a very- large loading of KCl (1:1 w/w KCI/PVA). Despite relatively large active surface areas in the designs studied (stand-alone reference and combination pH), leakage rates of KCl are remarkably low. pH measurements in ultrapure water and comparative measurements in common buffer solutions against standard reference electrodes confirm the stability of the potential developed across the junction to be very stable. Impedance studies verify the importance of the KCl doping for realization of the low resistance and attractive electrochemical properties of the material.

Journal ArticleDOI
TL;DR: In this paper, the authors compared simple formulae valid for all barrier heights for the longitudinal relaxation time of a single domain ferromagnetic particle with uniaxial anisotropy with the exact solution.

Journal ArticleDOI
TL;DR: Rabbit anti‐cathepsin L IgG was shown to bind to the catheps in L enzyme and inhibit its ability to cleave IgG molecules.
Abstract: SUMMARY Fasciola hepatica secretes a cathepsin L proteinase that is suggested to play an in vivo role in immunoprotection since the enzyme can cleave host immunoglobulin. In the present report, rabbit anti-cathepsin L IgG was shown to bind to the cathepsin L enzyme and inhibit its ability to cleave IgG molecules. Cathepsin L can prevent the antibody-mediated attachment of eosinophils to newly excysted juveniles in in vitro assays; however, if anti-cathepsin L IgG are mixed with the cathepsin L prior to the addition of the enzyme to the assay, eosinophils attach to the newly excysted juveniles. Thus it is possible to prepare antibodies that can bind and disrupt the biological activity of the F. hepatica cathepsin L.


Journal ArticleDOI
TL;DR: In this paper, a review of sensor-related calixarene research prior to 1994 is presented, identifying current trends in sensor research which are influencing the types of derivatives being synthesized and methods of evaluation, such as the increasing popularity of optical modes of transducing host-guest interaction.
Abstract: The well-known selective receptor properties and ease of structural modification makes calixarene derivatives attractive materials for use in chemical sensors. This review looks at the history of sensor-related calixarene research prior to 1994 and identifies current trends in sensor research which are influencing the types of derivatives being synthesised and methods of evaluation, such as the increasing popularity of optical modes of transducing host-guest interaction. Future possibilities are briefly discussed and the need for more fundamental studies highlighted.

Journal ArticleDOI
TL;DR: In this paper, the triphenylmethane dye, malachite green (Colour Index C.I. Basic Green 4), was determined in its chromatic form in drinking and river water using high-performance liquid chromatography with amperometric detection at a carbon fibre electrode.

Journal ArticleDOI
TL;DR: The use of calixarene-based chemically modified carbon paste electrodes (CMCPEs) in voltammetric analysis is reported in this paper, where the presence of alkali metal ions in the sample solution was found to have an adverse effect on electrode response, due to the preferable binding of these ions by the calixarella units immobilized in the carbon paste.
Abstract: The use of calixarene-based chemically modified carbon paste electrodes (CMCPEs) in voltammetric analysis is reported here. A polymeric calixarene I was incorporated successfully and used for the accumulation of lead (II), copper(II), and mercury(II) ions with subsequent anodic stripping voltammetry as the determination step. The electrode response depended on the calixarene content, the electrolyte, and the preconcentration time and analyte concentration as well as the constituents of the sample matrix. The presence of alkali metal ions in the sample solution was found to have an adverse effect on electrode response, due to the preferable binding of these ions by the calixarene units immobilized in the carbon paste. Attempts to overcome this interference employed a nonpolymeric sulfur-containing calixarene, the thioamide II, in the electrode. The stripping current was not enhanced by introduction of this compound as an electrode modifier, perhaps due to adsorption of the calixarene on the carbon partnicles via its metal ion binding site. However, the application of calixarenes to voltammetric methods of analysis is demonstrated and provides an additional use of calixarenes in electroanalysis.