Academic literature on the topic 'Ion selective potentiometry'

This paper presents experimental and theoretical data regarding the preparation and characterization of three liquid-membrane electrodes, which have not been mentioned in the specialized literature so far. The active substances, the solutions of which in nitrobenzene formed the membranes on a graphite rod, are simple complex combinations of Cu(II) and Ni(II) ions with an organic ligand belonging to the Schiff base class: N-[2-thienylmethilidene]-2-aminoethanol (TNAHE). The Cu2+ -selective and Ni2+ -selective electrodes were used to determine the copper and nickel ions in aqueous solutions, both by direct potentiometry and by potentiometric titration with EDTA. They were also used for the determination of Cu2+ and Ni2+ ions in industrial waters by direct potentiometry.

Abstract. A graphene paper-based flexible solid-contact ion-selective electrode (SC-ISE) was developed to detect lead ion sensitively. Graphene paper obtained via a simple vacuum filtration method was used as the electrode substrate for direct coating of an ion-selective membrane. The Nernstian slope of the prepared paper-based potentiometric sensor toward lead ion detection was demonstrated as 29.4 mV per decade. A detection limit as low as 2.5 × 10-7 mol L-1 was achieved. Reversed chronopotentiometry and water layer test revealed that the graphene paper-based SC-ISE possessed excellent potential stability because of the hydrophobicity of graphene paper. Furthermore, reliable data were obtained from the detection of lead ion levels in real water samples using the graphene paper-based potentiometric sensor, which shows great potential in practical application. Keywords: Graphene paper, Heavy metal, Ion-selective electrode, Potentiometry, Water sample.

This paper presents experimental and theoretical data regarding the design, characterization and analytical applications of a non-expensive, liquid-membrane ion-selective electrode for Pb2+ ions. The membrane is a solution of the active complex formed by Pb2+ ions with dibenzo-18-crown-6-ionophore (DB-[18]-C-6) extracted in propylene carbonate (PC). The successful application of the developed electrode for the determination of Pb2+ ions in aqueos solution samples by direct potentiometry and potentiometric titration is presented. For the presented analytical results, there are insignificant systematic errors between the direct potentiometric method with the developed ion-selective electrode and atomic absorption spectrometry. .

Abstract We evaluated the IL Monarch random-access centrifugal analyzer for measurement of Na+, K+, and Cl- by an indirect potentiometric method. For different concentrations of control material, the total precision (CV) ranged between 0.82% and 1.14% for the three electrolytes; linearity was acceptable within a range of 103 to 215 mmol/L for Na+, 1.6-15.25 mmol/L for K+, and 80-173 mmol/L for Cl-. Data correlated well with those by flame photometry for Na+ and K+ and with those by coulometry for Cl-, both for various biological materials--sera, urines, dialysis fluids--and commercial control materials from various producers. Stability of the potentiometric signal was acceptable: daily variations were 0.2 mV for Na+, 0.05 mV for K+, and 0.03 mV for Cl-. Accordingly, we conclude that the system supplies reproducible and accurate results while being easy to use and requiring little maintenance. The use of indirect potentiometry offers results consistent with those obtained with traditional methods, and easily interpretable by clinical staff. However, better information about the actual ion activity in the tested sample for certain pathologies such as hyperlipemia and dysproteinemia could be obtained by methods involving direct potentiometry.

Preparation and performance of a cost effective silver sulfide based bromide selective membrane is described. A solid contact between membrane and body of the electrode was examined as an ion-selective electrode by determining S2- and Br- ions by direct potentiometry. A linear response to bromide ion from 2 x 10-5 to 10-1 M with a slope of 57.3 mV per decade [Br-] is observed. The membrane has a very short response. It gives excellent results as an indicator electrode for potentiometric titration.DOI: http://dx.doi.org/10.3126/jncs.v27i1.6668 J. Nepal Chem. Soc., Vol. 27, 2011 100-106

Some models of ion-selective electrodes (ISE) and other methods have been elaborated, to quantify nitrate levels in environmental samples (water, fruits, vegetables and others), using direct potentiometry

The stability of sodium complexes with poly-carboxylic and polyamino-carboxylic acids is investigated with ion-selective electrode-Na⁺ potentiometry, working at strictly constant ionic strength.

Описана конструкция и электроаналитические характеристики ионселективного электрода (ИСЭ) для количественного определения метформина. В качестве электродноактивных соединений в ИСЭ были использованы ионные ассоциаты метформина с фосфорновольфрамовой(ФВК), фосфорномолибденовой(ФМК) и кремний вольфрамовой кислотами (КВК). Проведено потенциометрическое определение метформина в фармацевтических препаратах. The construction and electroanalytical characteristics of ion-selective electrode (ISE) for metformin are described. Ion pair of metformin with heteropolyacids were tested as electroactive materials for ionometric sensor controls. The ISE was used for direct potentiometry of metformin.

The role of magnesium is acknowledged in human physiology even though it is incompletely understood,a nd measuremenot f ionized magnesium by ion-selective electrode analysers is becoming commoner as recent research has alerted clinicians to its importance. Standardisation of ionized magnesium in blood samples in the form of a reference method is required. A prototype reference cell, which was developed for the reference method for ionized calcium, has been tested and found to perform well for magnesium. Selectivity coefficients, and the effects of pH and of proteins on various magnesium selective membranes have been determined. None of these membranes showed sufficient selectivity for magnesium over calcium and sodium for use with serum samples without simultaneous measurement of calcium. Knowledgeo f magnesiums peciationis requiredf or a full understanding of its role in physiology. Stability constants for magnesium and calcium with various ligands have been determined by using a new method in which a pH electrode and a Mg (or, Ca) electrode have been employed simultaneously in alkalimetric titrations. The' results were analysed using the program SUPERQUAD. In general, agreement was very good between values obtained from titrations with Mg (or Ca) electrodes and from pH. The protonation constants of the ligands were also determined and agree well with literaturev alues.R esultsf or Mg-citrate,l actate,g lycinate,a spartatea nd glutamatec omplexationc onstantsc omparew ell with recentlyp ublishedd ata. New systems investigated were Mg-pyroglutamate (Mg-5-oxo-2- pyrrolidinecarboxylic acid) and Mg-pyridoxine (Mg-3-hydroxy-4,5- bis(hydroxymethyl)-2-methylpyridine). Also HEPES (N-(2-hydroxyl) piperazine-N-ethanesulfoniacc id), used in calibration standardsa s a pH buffer, was found not to complex magnesium at physiological pH.

The aim of this thesis is the development of solid contact ion selective electrodes, ISEs, where the transducer layer is made of a network of carbon nanotubes.

Potentiometric classical ion selective electrodes (ISEs) have been used for analytical applications since the beginning of 1900's. Determination of pH by a glass membrane ion selective electrode emerged at the beginning, being the first ISEs developed. pH glass electrode is still one the most useful and robust sensors for routine measurements both in laboratories and industries.

Throughout the years, new technologies, ideas and designs have been developed and incorporated successfully in the potentiometric fields so as to provide answers to the new society's needs. Therefore, the ion selective electrodes developed in this thesis are a step further in the progress of ISEs and must be considered as products of the scientific envisioning, growth, and interdisciplinary cooperation of many research teams over many years of continuous efforts.

The sensing part can be regarded nowadays as well developed, although it has been during only the last few years when considerable improvements have taken place in the development of new polymeric membranes, ionophores and lipophilic ions. Moreover, the understanding of the theoretical sensing mechanism has been a powerful solid backbone in the rise of ISEs.

Miniaturization of classical ISEs requires making all solid contact electrodes to avoid the intrinsic drawbacks of the inner solution. In this manner, the transduction layer has been the focus of attention for the two last decades. New solid contact transducers having the capacity to convert an ionic current into an electronic current have been emerging. Within them, conducting polymers have played an important role in the transduction of the potentiometric signal, being the most used in solid contact ion selective electrodes (SC-ISEs) up to now. However, the behaviour of conducting polymers can be further improved. For instance, their sensitivity to light one of main operational issues yet to be solved.

In the present context of searching for new materials able to transduce potentiometric signals we selected and tested carbon nanotubes (CNTs). CNTs, which were rediscovered by Ijima in 1991, display excellent electronic properties in terms of signal transduction. In addition, due to their chemical reactivity CNTs can be easily functionalized with receptors or other functional groups. In fact, depending on the type of functionalization the macroscopic and microscopic properties of CNTs can be drastically changed. This nanostructured material had not been used previously as a solid contact material in ISEs.

The main aim of this thesis is to demonstrate that CNTs can act as a clean and efficient transducer in SC-ISEs overcoming the drawbacks displayed by the previously assayed solid contact materials. The developed electrodes were used in different conditions to determine several ions in different sample types, demonstrating the capabilities of this nanostructured material.
The thesis has been structured in different chapters, each one containing the following information:

· Chapter 1 provides a short historical overview of potentiometric ISEs. The evolution from the "classical ISEs" to the SC-ISEs is briefly illustrated. Once the motivation for thesis is described, the general and specific objectives of the thesis are reported.
· Chapter 2 reports the scientific foundations of the developed electrodes. All components of the ISE, sensing layer, transducers and detection systems are introduced. Analytical performance characteristics of ISEs are also described.
· Chapter 3 corresponds to the experimental part. Reagents, protocols, procedures and instruments used in the thesis are reported.
· Chapter 4 provides the demonstration that CNTs can act as a transducer layer in SC-ISEs. The first SC-ISEs based on CNTs are characterized by electrochemical and optical techniques.
· Chapter 5 contains the experimental results that lead to the elucidation of the possible transduction mechanism of CNTs in SC-ISEs. Electrochemical impedance spectroscopy (EIS) is employed as the main characterization technique.
· Chapter 6 is composed of four sections reporting different analytical applications. In the first section, the common pH electrode is developed using a solid contact technology based on CNTs. In the second section, the development of SC-ISEs based on a new synthetic ionophore selective to choline, and CNTs as transducers is shown. In the third section, watertight and pressure-resistant SC-ISEs based on CNTs are developed and tested in aquatic research to obtain information about the gradient profiles along the depth of the lakes. In the fourth section, SC-ISEs based on CNTs are adapted for the on-line control of a denitrification catalytic process.
· Chapter 7 reports the possibilities of miniaturization of the SC-ISEs based on CNTs to reach a nanometric electrode. Potentiometric and optical characterizations are described in this section. Moreover, a discussion about the limitations of the real miniaturization in potentiometry is undertaken.
· Chapter 8 points out the conclusions of the thesis. In addition, future prospects are suggested.
· Finally, several appendices are added to complete the doctoral thesis.
El principal objetivo de esta tesis es el desarrollo de electrodos selectivos de iones de contacto sólido, ESIs-CS, utilizando como capa transductora una red compuesta de nanotubos de carbono.

Los electrodos potenciométricos selectivos de iones han sido utilizados en aplicaciones analíticas desde comienzos de 1900. La determinación de pH mediante electrodos de vidrio selectivo de iones fue el primer ESI desarrollado. Hoy en día, el electrodo de vidrio para la determinación de pH es todavía uno de los más útiles y robustos sensores utilizados en mediciones rutinarias tanto en laboratorios como en industrias.

A lo largo de los años, nuevas tecnologías, ideas y diseños han sido desarrollados e incorporados satisfactoriamente en el campo potenciométrico proporcionando soluciones a las necesidades en continua evolución de la sociedad. De esta manera, los electrodos selectivos de iones desarrollados en esta tesis son un paso más en el progreso de los ESIs y deben ser considerados como el producto de una sólida base científica, del crecimiento y de la cooperación interdisciplinaria de diversos grupos de investigación durante varios años.

La parte del sensor donde tiene lugar el reconocimiento químico y donde se genera el potencial dependiente de la muestra en estudio en los ESIs se puede considerar, en estos días, ampliamente desarrollada, aunque considerables mejoras han tenido lugar durante los últimos años, especialmente en el desarrollo de nuevas membranas poliméricas, ionóforos e iones lipofílicos. Sobretodo, el estudio y la comprensión del mecanismo teórico del sensor ha sido muy importante en el crecimiento y desarrollo de los ESIs.

El concepto de electrodos selectivos de iones de estado sólido surge como requisito vital para evitar las intrínsecas desventajas de la solución interna, en el proceso de miniaturización de los ESIs clásicos. De esta forma, la capa transductora ha sido el principal punto de atención durante dos décadas. Así, nuevos transductores de contacto sólido con la capacidad de convertir una corriente iónica en una corriente electrónica han sido desarrollados. Entre ellos, los polímeros conductores han jugado un importante papel en la transducción de la señal potenciométrica, siendo éstos los más empleados en los electrodos selectivos de iones de contacto sólido (ESIs-CS). Sin embargo el comportamiento de los polímeros conductores puede ser mejorado. Por ejemplo, la sensibilidad hacia la luz de estos materiales es un inconveniente todavía no resuelto.

En este contexto de investigación de nuevos materiales capaces de actuar como transductor de una señal potenciométrica, se han escogido y estudiado los nanotubos de carbono (NTCs) como transductores. Los NTCs fueros redescubiertos por Ijima en 1991, y muestran excelentes propiedades electrónicas en términos de traducción de señal. Además, debido a su reactividad química, los NTCs pueden ser fácilmente funcionalizados con receptores u otros grupos funcionales. De hecho, sus propiedades macroscópicas y microscópicas pueden ser afectadas drásticamente dependiendo del tipo y grado de funcionalización. Este material nanoestructurado no había sido previamente utilizado como transductor en ISEs.

El principal propósito de esta tesis es demostrar que los nanotubos de carbono pueden actuar de forma eficiente como transductor en electrodos selectivos de iones de estado sólido logrando vencer las desventajas de los transductores previamente mencionados. Los electrodos desarrollados fueron usados en diferentes condiciones para determinar distintos iones en diversos tipos de sistemas, demostrando las extraordinarias capacidades de este material nanoestructurado.


Esta tesis ha sido estructurada en capítulos que contienen la siguiente información:

· El Capítulo 1 proporciona una breve visión histórica de lo electrodos potenciométricos selectivos de iones. Se ilustra la evolución desde los "clásicos ESIs" hasta los actuales "ESIs-CS". Además se señalan en esta sección los objetivos generales y específicos.
· El Capitulo 2 contiene las bases científicas de los electrodos desarrollados. Se introducen todos los componentes que integran un ESI, tales como: capa reconocedora, capa transductora y sistema de detección. A continuación se describen los parámetros analíticos de calidad de los ESIs.

· El Capitulo 3 describe la parte experimental. Se recogen los reactivos, protocolos, procedimientos e instrumentos usados a lo largo de la tesis.
· El Capitulo 4 provee de la demostración de que los NTCs pueden actuar eficientemente como capa transductora en SC-ISEs. Se caracteriza el primer ESI-CS integrado por NTCs mediante técnicas ópticas y electroquímicas.
· El Capitulo 5 contiene los resultados experimentales que permiten la posible elucidación del mecanismo de transducción de los NTCs en los ESIs-CS. La Espectroscopia de Impedancia Electroquímica (ESI) es utilizada como la principal técnica de caracterización.
· El Capitulo 6 está integrado por cuatro secciones con diferentes aplicaciones analíticas. En la primera sección, se desarrolla un electrodo de pH que usa NTCs como nueva tecnología transductora en ESIs-CS. En la segunda sección se muestra el desarrollo de un ESI-CS integrado por un ionóforo sintético selectivo a colina, y NTCs como transductores. En la tercera sección, ESIs-CS basados en NTCs, resistentes a altas presiones y totalmente herméticos, se desarrollan y prueban en investigaciones acuáticas con la finalidad de obtener información sobre los gradientes de concentración de iones en función de la profundidad de un lago. En la cuarta sección ESIs-CS basados en NTCs se adaptan para el control on-line de un proceso catalítico de desnitrificación.
· El Capitulo 7 presenta la posibilidad de la miniaturización de los ESIs-CS basados en NTCs logrando obtener un electrodo nanométrico. Se muestran en esta sección la caracterización óptica y potentiométrica. Además, se discuten las limitaciones de la miniaturización real de los ESIs en potenciometría.
· El Capitulo 8 contiene las conclusiones de la tesis. Adicionalmente, se sugieren las perspectivas futuras del trabajo presentado.
· Finalmente, se añaden algunos apéndices como complemento de la tesis doctoral.

RESUME

Le travail de thèse porte sur le développement d’électrodes sélectives originales et performantes pour l’analyse de composés d’intérêt pharmaceutique.

La partie introductive traite des notions relatives à l’électrochimie mais également de notions sur les molécules médicamenteuses étudiées, en l’occurrence les principes antipaludéens et l’iode.

La partie expérimentale se subdivise en deux parties distinctes selon le type d’électrodes sélectives auxquelles font appel les techniques électrochimiques.

La première partie concerne l’élaboration, la caractérisation et l’application des électrodes potentiométriques à membrane polymérique incluant une paire d’ions et sélectives à diverses molécules organiques pharmacologiquement actives (antipaludéens). Leur application aussi bien en analyse pharmaceutique qu’en cinétique de dissolution est décrite.

La deuxième partie est consacrée à l’élaboration d’un type de senseur ampérométrique original à pâte de carbone à base d’argent micronisé ou colloïdal et à la comparaison de ses performances avec l’électrode d’argent métallique. L’intérêt analytique est mis en évidence par la détermination quantitative des iodures.

Les différents aspects susceptibles d’influencer leur comportement, dont la nature des agents précipitants (tétraphénylborate de sodium et le tétrakis (4-chlorophényl) borate de potassium) et de plastifiants ont été investigués.

Les bonnes performances des ces électrodes en analyse quantitative ont permis d’explorer les possibilités de leur utilisation à l’étude de la cinétique de dissolution.

L’ampérométrie à électrode à pâte de carbone modifiée à base d’argent à l’échelle micronisée (35% m/m) couplée à la chromatographie liquide ionique s’est avérée très sensible vis-à-vis des iodures en particulier et des halogénures en général. Les facteurs susceptibles d’influencer les grandeurs de séparation et la réponse de l’électrode ont été investigués et l’exploitation du signal ampérométrique permet le dosage sélectif et rapide de faibles concentrations en iodures. Les informations fournies par les mesures réalisées en voltampérométrie cyclique à l’aide des mêmes électrodes permettent une bonne compréhension mécanistique quant au mode de détection ampérométrique évitant ainsi toute confusion à ce sujet et permettant l’optimisation du processus de détection.

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ABSTRACT

This thesis describes the development of original and high performance selective electrodes for the analysis of several pharmaceutical compounds.

The introduction describes the pharmaceutical compounds of interest (antimalarial drugs and iodine) and provides an overall understanding of the electrochemical groundwork pertaining to their analysis.

The experimental aspect of the thesis is divided into two parts, each according to the type of electrode and electrochemical technique used for the analysis.

The first part describes the design, characterization, and application of polymer membrane based ion selective potentiometric electrodes. Selectivity was provided by including ion pairs of several antimalarial drugs into the membrane. The feasibility of use of these electrodes in pharmaceutical analysis as well as in dissolution trials is also described in this part.

The second part describes the design of an original silver-modified carbon paste amperometric sensor and compares its performances to those of a plain metallic silver electrode. The electrode has been modified by silver microparticles or by silver nanoparticles. Quantitative iodine determination serves to prove the usefulness of this new sensor in analytical chemistry.

Different aspects, such as the nature of the counter ions (sodium tetraphenylborate and potassium tetrakis (4-chlorophenyl) borate) and the plastifying agents that are likely to influence electrode behaviour have been investigated.

Since the electrodes have been shown to perform well in quantitative analysis, the possibility of use in dissolution trials was explored.

Micronized silver-modified carbon paste electrode (35% Ag m/m) coupled to anionic-exchange liquid chromatography with amperometric detection was shown to be very sensitive with regards to the assay of halogenides in general and iodide in particular. After having investigated the various factors likely to influence chromatographic separation and electrode response, it was shown that the sensor could be used to rapidly and selectively determine low iodide concentrations in complex samples. Cyclic voltammetric analysis provided information concerning the mechanisms allowing amperometric detection, thus allowing an optimisation of the detection procedures.

Doctorat en Sciences biomédicales et pharmaceutiques
info:eu-repo/semantics/nonPublished

Single ion activity coeffients of NaCl, KCl, HCl and CaCl2 in aqueous solution have been estimated by means of ion selective electrode (ISE) potentiometric measurements. Two methods are described for the calibration of the electrodes within the extended Debye-Hückel concentration range, using the Henderson-Bates approximation for the diffusion potential arising at the reference electrode. The consistency of the results indicates that the junction potentials in the examined systems calculated by the Henderson-Bates approximation are of reasonable precision. The published methods and data might be useful to develop single ion parameters for individual ion activity coefficient models.

Ziel der Untersuchungen war die Charakterisierung der Protonierungs-, Komplexbildungs- und Verteilungseigenschaften von tripodalen Azaliganden unter Anwendung thermodynamischer und spektroskopischer Verfahren. Im Vordergrund stand dabei der Einfluß des Lösungsmittels auf die zugrundeliegenden Gleichgewichte. Ausgehend von dem Aminopodanden Tris(2-aminoethylamin) (tren) wurden für eine Reihe abgeleiteter Verbindungen mit unterschiedlichen Stickstoffdonorfunktionen und Substituenten Faktoren untersucht, welche die beteiligten Gleichgewichte beeinflussen. Das Protonierungsverhalten der Polyaminverbindungen ist im starken Maße von elektrostatischen, elektronischen und Solvenseinflüssen abhängig, welche durch den Abstand der benachbarten Aminfunktionen, die Substitution am Aminstickstoffatom und die sterischen Eigenschaften der Substituenten bestimmt werden. Faktoren, welche die Solvatation der Aminfunktionen verringern, führen zu einer Verringerung der Protonierungskonstanten. Zudem beeinflussen die Zusammensetzung der verwendeten Methanol-Wasser-Gemische sowie das verwendete Leitsalz die Protonierungskonstanten z.T. deutlich. Die Komplexbildung der untersuchten Azapodanden mit Ag+ in Methanol zeigt Unterschiede, welche hauptsächlich auf die unterschiedliche Basizität von Imin- bzw. Aminstickstoffatomen sowie Substituenteneffekte zurückzuführen sind. Von sterisch aufwendigen Substituenten an den Donorfunktionen der Podandarme können zudem destabilisiernde Effekte infolge der Beeinflussung der Koordinationsgeometrie von Ag+ ausgehen. Heteroditope Tetraazacryptanden zeigen gegenüber abgeleiteten offenkettigen Podanden erhöhte Stabilitätskonstanten, wobei auch die Verknüpfungsposition der tripodalen Einheiten am Phenylspacer und die Bindung von Wasser im Käfighohlraum eine Rolle spielen. Lösungsmittelpolarität und Gegenion haben einen deutlichen Einfluß auf die Komplexbildung mit Ag+. Der Schwerpunkt von Untersuchungen an Zweiphasensystemenen wäßrig-organisch lag auf dem Übergang von Wasser in die organische Phase unter dem Einfluß von extrahierten Spezies bei der Kationen- und Anionenextraktion. Mit der Verteilung von Liganden und Kationen- bzw. Anionenkomplexen lassen sich Änderungen des Wassersättigungsgehaltes in der niedrigpolaren organischen Phase registrieren, die mit der unterschiedlichen Hydratation der Spezies korrelieren. Qualitativ wurde die Hydratation von Azapodanden mittels IR- und 1H-NMR-Spektroskopie nachgewiesen, wobei auch Hinweise auf bestimmte, die Hydratation verringernde Faktoren, wie intramolekulare Wasserstoffbrücken, erhalten wurden. Quantitativ konnten mittels Karl-Fischer-Titration und Verteilungsmessungen Hydratationszahlen für ausgewählte Ligansysteme bestimmt werden. Extrahierte Komplexe der Verbindungen mit Ag+, Co2+, Ni2+ und Zn2+ zeigen eine gegenüber den freien Komplexbildnern veränderte Hydratation. Bei Ag+ kann in allen Fällen von einer deutlichen Verringerung der Hydratationszahlen ausgegangen werden. Für die zweifachgeladenen Kationen konnte kein klarer Nachweis erbracht werden. Es ergeben sich aber Hinweise, wonach zum Teil keine Verringerung auftritt, was auf eine zusätzliche Koordinationsstellen von Wasser am Kation hinweist. Bei der Iodidextraktion treten bei gleichzeitiger pH-Abhängigkeit mehrere Komplexspezies auf, was die Bestimmung von Hydratationszahlen erschwert. Als hilfreich erwies sich die Simulation für verschiedene mögliche Zusammensetzungen. Dabei stellte sich heraus, daß der 1:1-Komplex des untersuchten monoprotonierten Aminopodanden in Chloroform wahrscheinlich stärker hydratisiert ist als der freie Ligand, während die entsprechende 1:2-Spezies (Ligand:Iodid) eine ähnliche oder schwächere Hydratation aufweist als der Ligand.

Ziel der Untersuchungen war die Charakterisierung der Protonierungs-, Komplexbildungs- und Verteilungseigenschaften von tripodalen Azaliganden unter Anwendung thermodynamischer und spektroskopischer Verfahren. Im Vordergrund stand dabei der Einfluß des Lösungsmittels auf die zugrundeliegenden Gleichgewichte. Ausgehend von dem Aminopodanden Tris(2-aminoethylamin) (tren) wurden für eine Reihe abgeleiteter Verbindungen mit unterschiedlichen Stickstoffdonorfunktionen und Substituenten Faktoren untersucht, welche die beteiligten Gleichgewichte beeinflussen. Das Protonierungsverhalten der Polyaminverbindungen ist im starken Maße von elektrostatischen, elektronischen und Solvenseinflüssen abhängig, welche durch den Abstand der benachbarten Aminfunktionen, die Substitution am Aminstickstoffatom und die sterischen Eigenschaften der Substituenten bestimmt werden. Faktoren, welche die Solvatation der Aminfunktionen verringern, führen zu einer Verringerung der Protonierungskonstanten. Zudem beeinflussen die Zusammensetzung der verwendeten Methanol-Wasser-Gemische sowie das verwendete Leitsalz die Protonierungskonstanten z.T. deutlich. Die Komplexbildung der untersuchten Azapodanden mit Ag+ in Methanol zeigt Unterschiede, welche hauptsächlich auf die unterschiedliche Basizität von Imin- bzw. Aminstickstoffatomen sowie Substituenteneffekte zurückzuführen sind. Von sterisch aufwendigen Substituenten an den Donorfunktionen der Podandarme können zudem destabilisiernde Effekte infolge der Beeinflussung der Koordinationsgeometrie von Ag+ ausgehen. Heteroditope Tetraazacryptanden zeigen gegenüber abgeleiteten offenkettigen Podanden erhöhte Stabilitätskonstanten, wobei auch die Verknüpfungsposition der tripodalen Einheiten am Phenylspacer und die Bindung von Wasser im Käfighohlraum eine Rolle spielen. Lösungsmittelpolarität und Gegenion haben einen deutlichen Einfluß auf die Komplexbildung mit Ag+. Der Schwerpunkt von Untersuchungen an Zweiphasensystemenen wäßrig-organisch lag auf dem Übergang von Wasser in die organische Phase unter dem Einfluß von extrahierten Spezies bei der Kationen- und Anionenextraktion. Mit der Verteilung von Liganden und Kationen- bzw. Anionenkomplexen lassen sich Änderungen des Wassersättigungsgehaltes in der niedrigpolaren organischen Phase registrieren, die mit der unterschiedlichen Hydratation der Spezies korrelieren. Qualitativ wurde die Hydratation von Azapodanden mittels IR- und 1H-NMR-Spektroskopie nachgewiesen, wobei auch Hinweise auf bestimmte, die Hydratation verringernde Faktoren, wie intramolekulare Wasserstoffbrücken, erhalten wurden. Quantitativ konnten mittels Karl-Fischer-Titration und Verteilungsmessungen Hydratationszahlen für ausgewählte Ligansysteme bestimmt werden. Extrahierte Komplexe der Verbindungen mit Ag+, Co2+, Ni2+ und Zn2+ zeigen eine gegenüber den freien Komplexbildnern veränderte Hydratation. Bei Ag+ kann in allen Fällen von einer deutlichen Verringerung der Hydratationszahlen ausgegangen werden. Für die zweifachgeladenen Kationen konnte kein klarer Nachweis erbracht werden. Es ergeben sich aber Hinweise, wonach zum Teil keine Verringerung auftritt, was auf eine zusätzliche Koordinationsstellen von Wasser am Kation hinweist. Bei der Iodidextraktion treten bei gleichzeitiger pH-Abhängigkeit mehrere Komplexspezies auf, was die Bestimmung von Hydratationszahlen erschwert. Als hilfreich erwies sich die Simulation für verschiedene mögliche Zusammensetzungen. Dabei stellte sich heraus, daß der 1:1-Komplex des untersuchten monoprotonierten Aminopodanden in Chloroform wahrscheinlich stärker hydratisiert ist als der freie Ligand, während die entsprechende 1:2-Spezies (Ligand:Iodid) eine ähnliche oder schwächere Hydratation aufweist als der Ligand.

AbstractSPES (Selective Production of Exotic Species) is a large facility, currently under advanced construction at the INFN-LNL (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro) for the production of Radioactive Ion Beams (RIBs). Coordinated efforts are being dedicated to the development and upgrading of both the accelerator complex and the up-to-date experimental set-ups. This paper describes a work of upgrading as far as the inspection and maintenance of the system is concerned, and it deals with human-centered design methods to reduce the time spent in the radioactive environment of the facility during ordinary maintenance operations and to simplify them, also considering stress conditions of the operator and the mandatory wearable radiation protection devices (such as tracksuit, gloves, oxygen tank mask) which make simple operations difficult.

The principles for optimal managing a composition of base solutions for the molten-salt reactor are formulated here for ensuring the given properties and exchange processes as a selective extracting of salt components. The correction of melt properties can be carried out by means of impurity additives parallel with the forced and controllable variation of reduction-oxidation (redox) potential of the non-stoichiometric salts. The accent is done on a possible application of the potentiometer for monitoring and managing of the properties of MSR fuel compositions. For this, one can use the precision methods of e.m.f and the coulomb-metric titration of sodium (lithium) in a galvanic cell upon the base of Na+(Li+)-β″-Al2O3 solid electrolyte with cation conductivity.

Computer-Assisted Experimental Work (CAEW) consists in the incorporation of computer-connected apparatus in the laboratory. This is a new insight into teaching of Classical Analytical Chemistry, wherein the experiments are usually manually conducted. However, it does not represent a complete break with traditional methodology, as the design and goal of the experiment are essentially the same. In this work, we present the implementation of CAEW to a practical included in the Laboratory part of “Analytical Chemistry IV”, taught at the fourth academic year of the Degree in Chemistry: “Potentiometric titration of a mixture of iodure and chlorure with silver”. Three couples of students used an Ag-ion selective electrode connected to a computer, while the other three couples employed a digital one. The results were comparable, though the computer-assisted method provided significant improvements, like; the students get familiar with new technologies at an accessible level, the titration can be visually followed on the screen via the titration curve, the calculations are automatically performed, allowing the detection of experimental and registration of mistakes, it avoids errors caused by the transcription and processing of the data, and the students achieve their practical disposing of the final results, and all their work corrected by the teacher.

Abstract A ballistic or compound pendulum is used either to determine the velocity of a projectile or as a laboratory tool to teach impact momentum and principle of work and energy. It also lends itself well to the study of energy losses caused by the inelastic impact of a projectile with a medium. One useful application of the latter use of these pendulums is in the investigation of the effects of medium characteristics on the energy loss and the design of more effective lethal weapons. A compound pendulum has been designed, instrumented and used to measure the energy losses during the plastic impact of a projectile with an arbitrary medium. The energy loss is calculated from the projectile velocity just before impact and the pendulum angular velocity immediately after impact or the pendulum maximum angular displacement. The angular displacement and velocity measurements are performed by a precision potentiometer and a PC-based data acquisition system in an automated manner to enable collection of extensive data in a reasonable period of time. The PC-based data acquisition used in this study is an in-house developed one that is capable of handling and storing massive amount of data and providing the ability to perform statistical and other computational analyses. This paper discusses the procedure for designing the impact pendulum, in particular the selection of proper transducers and the data acquisitions system, and gives an overview of the software that has been developed to fully automate the energy loss calculation.

Abstract Synthetic fibre ropes are in widespread use in maritime applications ranging from lifting to temporary and permanent mooring systems for vessels, fish farm, offshore equipment and platforms. The selection of synthetic ropes over conventional steel components is motivated by several key advantages including selectable axial stiffness, energy absorption and hence load mitigation, fatigue resistance and low unit cost. The long-term use of ropes as safety critical components in potentially high dynamic loading environments necessitates that new designs are verified using stringent qualification procedures. The International Organization for Standardization (ISO) is one certification body that has produced several guidelines for the testing of synthetic ropes encompassing quasi-static and dynamic loading as well as fatigue cycling. The paper presents the results of tension-tension tests carried out to ISO 2307:2010, ISO 18692:2007(E) and ISO/TS 19336:2015(E) on 12-strand rope with embedded electric cable constructions manufactured by Ashimori Industry Co. Ltd from Vectran fibres. The purpose of the tests was to characterise the performance of a novel strand construction (SSR) and compare this to a conventional 12-strand construction. Utilising the Dynamic Marine Component test facility (DMaC) at the University of Exeter several key performance metrics were determined including; elongation, minimum break load (MBL), quasi-static, dynamic stiffness and embedded cable resistance. During the ISO 2307:2010(E) test programme the samples were tested dry and during the ISO 18692:2007(E) and ISO/TS 19336:2015(E) test programmes the samples were fully submerged in tap water after being soaked in water for at least 24 hours. Two methods were used to quantify sample extension: i) an optical tracking system and ii) a potentiometer. Axial compression fatigue and cyclic loading endurance tests were also carried out on Vectran sample. Failure of the Vectran sample or embedded cable did not occur during tests carried out using DMaC. Further tests and sample analysis were also carried out by Ashimori Industry Co. Ltd. Quasi-static bedding-in at 50% MBS and cyclic load endurance test with 6000 cycles between 3.57% MBS and 53.6% MBS was completed. The Effective Working Length (EWL) was 3.821 m before testing and 3.974m after testing. The resistance of the cable increased from 9.6962 Ω to 9.7693Ω during the test and importantly the embedded cable did not fail. Each tensile loading cycle of the rope caused a measurable variation in wire resistance; approximately 0.01Ω. The data obtained during these tests will provide insight into the behaviour of these materials, which will be of use to rope manufacturers and mooring system designers, in addition to offshore equipment and vessel operators.

Synthetic fibre ropes are in widespread use in maritime applications ranging from lifting to temporary and permanent mooring systems for vessels, offshore equipment and platforms. The selection of synthetic ropes over conventional steel components is motivated by several key advantages including selectable axial stiffness, energy absorption (and hence load mitigation), fatigue resistance and low unit cost. The long-term use of ropes as safety critical components in potentially high dynamic loading environments necessitates that new designs are verified using stringent qualification procedures. The International Organization for Standardization (ISO) is one certification body that has produced several guidelines for the testing of synthetic ropes encompassing quasi-static and dynamic loading as well as fatigue cycling. This paper presents the results of tension-tension tests carried out to ISO 2307:2010, ISO 18692:2007(E) and ISO/TS 19336:2015(E) on three different 12-strand rope constructions manufactured by Ashimori Industry Co. Ltd from polyester and Vectran® fibres. The purpose of the tests was to characterise the performance of a novel 12-strand construction and compare this to a conventional 12-strand construction. Utilising the Dynamic Marine Component test facility (DMaC) at the University of Exeter several key performance metrics were determined including; elongation, minimum break load (MBL) and quasi-static and dynamic stiffness. During the ISO 2307:2010(E) test programme the samples were tested dry and during the ISO 18692:2007(E) and ISO/TS 19336:2015(E) test programmes the samples were fully submerged in tap water after being soaked for at least 24 hours. Two methods were used to quantify sample extension: i) an optical tracking system and ii) a draw-wire potentiometer. Axial compression fatigue and cyclic loading endurance tests were also carried out on two Vectran® samples. Further load-to-failure tests and sample analysis were also carried out by Ashimori Industry Co. Ltd. It was found that the MBL of the samples exceeded the values specified by the manufacturer (by 7.7–29.5% for the polyester samples) with failure occurring at the splices in all cases and minor abrasion noted in several locations. The measured MBL of the novel polyester Straight Strand Rope (SSR) construction was up to 16% higher than the conventional construction with increases of quasi-static and dynamic stiffness of up to 6.8%. Differences between the viscoelastic and viscoplastic behaviour of the samples were also noted. The data obtained during these tests will provide insight into the behaviour of these materials and different rope constructions which will be of use to rope manufacturers, mooring system designers in addition to offshore equipment and vessel operators.

The LHD 8 amphibious assault ship utilizes a hybrid propulsion plant, where the ship has the capability to be propelled by electric propulsion motors or gas turbine engines, all of which is controlled and monitored by a state-of-the-art Machinery Control System (MCS). Unlike the previous ships of the class which were steam powered, the hybrid drive is designed to allow economical low speed fuel efficiency on electric motors as well as a traditional gas turbine power plant for all other mission areas. This is expected to yield significant fuel savings over the life of the ship. The integrated machinery control system is likewise expected to reduce life cycle costs through reduced manning. The build specification for this ship class required that all MCS signals including the gas turbine alarms and shutdown functions be fully tested prior to initial light-off. Many of these functions are not activated, and therefore cannot be tested, until the Electronic Control Unit (ECU) senses that the gas turbine is running. Historically, previous ship classes used a manually-operated set of potentiometers to provide signals to a gas turbine ECU to simulate external inputs to allow testing of shutdown and alarm functions. For this newest class of engine however, the ECU is significantly more complex and requires the ECU to successfully progress through the start sequence, including sensed variables changing at expected rates, in order to activate the alarm and shutdown logic. In order to test this functionality, an engine simulator, physically interfaced to the ECU aboard the ship, was necessary. No system of this type is available or had ever been developed. Neither the engine or ECU manufacturer had a device for this purpose. The paper will discuss the development and implementation of a gas turbine simulator that incorporates an engine mathematical model fully compatible with the ECU controller, simulation hardware capable of supporting real-time system performance, signal conditioning necessary to provide/accept raw signals to/from the ECU, as well as a host laptop with software necessary to control simulator/stimulator and perform test functions. The paper will discuss the system requirements development, component selection, software and hardware development, and system integration and testing. Also discussed will be the results of bench testing as well as the final shipboard test results. Examples in the form of diagrams, photos, charts and schematics will be used. The paper will conclude with a discussion of the benefits of a dynamic gas turbine simulator and potential future applications.