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Background: Photo-electro-chemical (PEC) water splitting represents a promising technology towards an artificial photosynthetic device but many fundamental electronic processes, which govern long-term stability and energetics, are not yet fully understood. X-ray absorption spectroscopy (XAS), and particularly its high energy resolution fluorescence-detected (HERFD) mode, emerges as a powerful tool to study photo-excited charge carrier behavior under operating conditions. The established thin film device architecture of PEC cells provides a well-defined measurement geometry, but it puts many constraints on conducting operando XAS experiments. It remains a challenge to establish a standardized thin film exchange procedure and concurrently record high-quality photoelectrochemical and X‑ray absorption spectroscopy data that is unperturbed by bubble formation. Here we address and overcome these instrumental limitations for photoelectrochemical operando HERFD-XAS. Methods: We constructed a novel operando photo-electro-chemical cell by computer numerical control milling, guided by the materials' X‑ray and visible light absorption properties to optimize signal detection. To test the cell's functionality, semiconducting thin film photoelectrodes have been fabricated via solution deposition and their photoelectrochemical responses under simulated solar light were studied using a commercial potentiostat in a three-electrode configuration during HERFD-XAS experiments at a synchrotron. Results: We demonstrate the cell's capabilities to measure and control potentiostatically and in open‑circuit, to detect X‑ray signals unperturbed by bubbles and to fluently exchange different thin film samples by collecting high-resolution Fe K-edge spectra of hematite ( α -Fe 2O 3) and ferrite thin film ( MFe 2O 4, M= Zn, Ni) photoelectrodes during water oxidation. Conclusions: Our cell establishes a measurement routine that will provide experimental access of photo-electro-chemical operando HERFD-XAS experiments to a broader scientific community, particularly due to the ease of sample exchange. We believe to enable a broad range of experiments which acquired fundamental insights will spur further photoelectrochemical research and commercialization of water splitting technologies

In this article a possibility of application of the non-contact method for prediction the poultry eggs weight in storage period of 21 days was researched. A prediction assessment was made by shape features, capacitance, resistance and conductance of eggs. Feature vectors were selected and reduced data by principal component and partial least squares regression methods were used. A non-contact device was proposed and developed to determine the egg weight by video sensor and measurement cell. In order to obtain data for post-processing, a software application was designed. The developed algorithms and procedures were applied to determine the eggs weight, whereby that parameter of eggs could be predicted with the lowest relative error. The survey results show that the eggs weight could be predicted by the proposed system for contactless measurement with accuracy of 94-98%., В тази статия е проучена възможността за прилагане на безконтактен метод за прогнозиране масата на птичи яйца в период на съхранение от 21 дни. Направена е оценка на възможността за прогнозиране по признаци на формата, капацитет, електрическо съпротивление и електрическа проводимост на яйцата. Избрани са характеристични вектори и са използвани редуцирани данни при регресия по главни компоненти (PCR) и метод частична регресия на най-малките квадрати (PLSR). Предложено и разработено е безконтактно устройство за определяне масата на яйца чрез видео сензор и измервателна клетка. За получаване на данни за последваща обработка, е създадено програмно приложение. Разработените алгоритми и процедури са приложени за определяне масата на яйца, при което този параметър може да се прогнозира с най-ниската относителна грешка. Резултатите от изследването показват, че масата на яйцата може да се прогнозира чрез предложената система за безконтактно измерване с точност от 94-98%.

Calibration-independent nonresonant measurements can be employed to eliminate the need for calibration before microwave measurements. These methods generally assume that the location of the sample in its measurement cell is known after the sample is positioned or shifted within the cell and that the length of the measurement cell is known. In addition, in general these methods necessitate some sort of numerical analysis to retrieve the complex permittivity of the sample. In this research paper, we propose a calibration-independent nonresonant waveguide method to first eliminate measurement errors arising from inaccurate knowledge of the location of the sample within its cell (after shifting) and arising from improper knowledge of the length of the measurement cell and second to determine the complex permittivity explicitly. In addition, our proposed method needs scattering parameter measurements from three different measurement configurations – another improvement with respect to a similar calibration-independent method requiring measurements from four different configurations. Furthermore, it does not necessitate that the sample be flushed to the measurement cell. We analyzed repeatability of cell connection and investigated uncertainty in the measurement of complex permittivity for a change in length of the sample and the cell and when air gap present between sample surfaces and guide walls. We validated the proposed method by measuring the complex permittivity of polyethylene sample and distilled water at X-band (8.2–12.4 GHz). © 2017 Elsevier B.V.

Metrological non-destructive characterization of intense ( α , n) neutron sources (emission rate between 107 and 3 × 108 s−1 into 4 π sr solid angle) is a challenge for nuclear applications. In this article, we will present the design, development and in situ validation of two measurement cells especially dedicated to this characterization. The main goal consists in determining the absolute neutron emission rate of this type of neutron sources with relative uncertainties less than 5% (k=1). Another purpose is related to the qualitative and quantitative analysis of fission products present in irradiated neutron sources. Because of experimental constraints, acquisitions were carried out underwater which required a full remote control of the measurement cells. Neutron emission rate is assessed using three different non-destructive techniques: (i) global neutron counting, (ii) neutron activation using gold dosimeters and (iii) gamma-ray spectrometry. We will successively present the design step and associated constraints, main characteristics of measurement cells and associated laboratory characterization as well as experimental results obtained during the final in situ measurement campaign. The latter shows an excellent agreement regarding the neutron emission rate values provided by the three different non-destructive techniques and a relative combined standard uncertainty less than 5% (k=1) for the investigated neutron sources.

[ES] La espectroscopía de impedancia eléctrica es una técnica de caracterización de materiales enmarcada en las denominadas técnicas de evaluación no destructiva. El propósito del presente trabajo consiste en caracterizar la madera de pino silvestre mediante esta técnica en un rango de frecuencias de 500 Hz a 5 MHz. Así pues, se ha tratado de buscar la relación existente entre ciertas variables físicas propias de la madera y la respuesta eléctrica del material. Para ello ha sido necesaria la construcción de una celda de medida así como la elaboración de un método de calibración. La respuesta eléctrica del material se ha ajustado a un circuito equivalente distribuido en dos ramas, por métodos iterativos. Del análisis de dicho circuito se concluye que cada una de las ramas muestra un comportamiento eléctrico distinto, que podría llegar a ser ajustado a cada una de los tipos de madera que componen un anillo: madera temprana y madera tardía. Así mismo, se han encontrado correlaciones estadísticamente significativas entre parámetros propios de la madera y parámetros eléctricos., [EN] The electrical impedance spectroscopy is one of the non-destructive evaluation techniques. The aim of this paper consists on describing the electrical behavior of scots pine’s softwood into a frequency range from 500 Hz to 5 MHz. Therefore, the relationship among some physical variables from wood and the electric response has been investigated. In consequence, it has been necessary to build a measurement cell and creating a calibration method. An equivalent circuit has been fitted for the electrical response. This circuit has two branches that could describe the electric behavior from each of the phases of a wood ring: earlywood and latewood. In addition, statistically significant correlations have been found among wood parameters and electrical parameters.

We propose a new transmission-reflection method for measuring constitutive parameters of liquid samples inside an asymmetric measurement cell (a sample over a low-loss holder in vertical position inside an empty waveguide section). We derived reference-plane invariant expressions for constitutive parameters measurement of liquid samples from reference-plane dependent scattering parameters. In addition, we also applied a simple approach for unique determination of transformation factor and reference-plane distances. After, we also investigated how the performance of the proposed method could be improved by performing a differential uncertainty analysis. From this analysis, we found the following key results: (a) the accuracy of the proposed method could be enhanced for low-loss liquid samples by using thicker samples, and (b) the effect of constitutive parameters and the length of the (low-loss) sample holder on constitutive parameters measurements of liquid samples by the proposed method is a key parameter in increasing the accuracy of the measurements. Finally, we performed constitutive parameter measurements of distilled water and methanol to validate the proposed method and compared the proposed method with similar methods in the literature. From the measurements, we note that our method is especially useful for liquid sample measurements when the reference-plane transformation factors are not known a priori and/or if the measurements are carried out over a high frequency range. © 2013 Elsevier B.V.

Electrical impedance measurements of a suspension have to take into account the double layer impedance that results from a very thin charged layer formed at the electrode-electrolyte interface. A dedicated measuring cell that enables variation of the distance between the electrodes was developed to investigate the electrical properties of suspensions using two-electrode impedance measurements. By varying the distance between the electrodes it is possible to separate the double layer and the suspension impedance from the measured data. Electrical ‘lumped’ models have been developed from measured and extracted impedances. The error of non-inclusion of the double layer impedance has been analyzed. The error depends on the frequency of the measurement as well as the distance between the electrodes.

Este estudo teve por objetivo determinar os valores hematológicos de Tayassu tajacu (catetos) mantidos em cativeiro. Foram utilizados 26 catetos, sendo 21 adultos (13 machos e 8 fêmeas) e 5 filhotes (três machos e duas fêmeas), mantidos na Fazenda Experimental do Almada e no Laboratório de Etologia Aplicada, pertencente à Universidade Estadual de Santa Cruz, Ilheus, BA. Amostras de sangue foram colhidas, da veia cefálica, para realização dos hemogramas. A análise estatística foi obtida por meio do teste "t" de Student, com nível de significância de 95%. Na comparação entre os animais instalados em baias e piquetes não foi observada diferença significativa, no entanto observou-se um maior valor da proteína plasmática total nos machos (p

Im ersten Teil der Arbeit wurden die grundlegenden elektrochemischen Eigenschaften von Polyelektrolyten untersucht. Dazu wurden drei sehr reine, Imidazolium-basierte vinylische ionische Flüssigkeiten mit Bis(trifluormethansulfonyl)imid-Anionen und die daraus abgeleiteten Polyelektrolyte synthetisiert. Anschließend wurden diese per Impedanzspektroskopie sowohl in Reinform als auch in Mischungen mit Lithium-bis(trifluormethansulfonyl)imid untersucht. In einem weiteren Schritt wurde darüber hinaus die ionische Flüssigkeit 1-Ethyl-3-methylimidazolium-bis(trifluormethansulfonyl)imid zugegeben, um die Leitfähigkeit des Elektrolytmaterials zu erhöhen. Bei den Messungen der frequenzabhängigen ionischen Leitfähigkeit der reinen Polyelektrolyte bei verschiedenen Temperaturen stellte sich heraus, dass im Fall von Poly(3-Ethyl-1-vinylimidazolium)-bis(trifluormethansulfonyl)imid (P1) und Poly(3-Methyl-1-(4-vinylbenzyl)imidazolium)-bis(trifluormethansulfonyl)imid (P2) unterhalb der Glastemperatur zwei verschiedene Beiträge zur Leitfähigkeit separiert werden können. Im Fall von Poly(1-Butyl-3-methyl-2-(4-vinylphenethyl)imidazolium)-bis(trifluormethansulfonyl)imid (P3) war dies nicht der Fall. Ein wichtiger Unterschied zwischen den drei Polyelektrolyten ist die Distanz zwischen den kationischen Imidazoliumeinheiten der Seitenketten und der polyolefinischen Hauptkette. Die Flexibilität nimmt dabei von P1 nach P3 zu, in gleichem Maße nimmt die Unterscheidbarkeit der Ionenleitungsprozesse ab. Aufgrund einer Abschätzung des mittleren Verschiebungsquadrats der Anionen liegt der Schluss nahe, dass es sich bei den beiden Prozessen um intra- und interkationische Ionenbewegung handelt. Im zweiten Teil dieser Arbeit wurden drei neue Lithiumsalze auf ihre thermischen und elektrochemischen Eigenschaften hin untersucht. Es handelte sich dabei um die Vertreter Lithium-bis(pentafluorphenyl)amid LiN(Pfp)2, Lithium-pentafluorphenyl-trifluormethyl-sulfonylimid LiN(Pfp)(Tf) und Lithium-pentafluorphenyl-nonafluorbutyl-sulfonylimid LiN(Pfp)(Nf). Es stellte sich heraus, dass LiN(Pfp)2 thermisch nur bis etwa 100 °C stabil ist, während die anderen beiden Salze erst bei über 300 °C Zersetzungserscheinungen zeigen. Die geringe thermische Stabilität von LiN(Pfp)2 ist dabei wahrscheinlich dem deutlich schwächer ausgeprägten –I und –M Effekt der (Pfp)- im Vergleich zur (Tf)- oder (Nf)-Gruppe zuzuschreiben. Aus diesem Grund wurden LiN(Pfp)(Tf) und LiN(Pfp)(Nf) zur elektrochemischen Charakterisierung und dem Vergleich mit kommerziell erhältlichem LiN(Tf)2 sowohl im Festkörper als auch in Lösung herangezogen. Die Gleichstromionenleitfähigkeit im Festkörper bei 100 °C nimmt in der Reihenfolge LiN(Pfp)(Tf) > LiN(Tf)2 > LiN(Pfp)(Nf) ab, wohingegen diese Reihenfolge für die ermittelte Aktivierungsenergie und die Aktivierungsentropie vertauscht ist. Hier gilt LiN(Tf)2 > LiN(Pfp)(Nf) ≈ LiN(Pfp)(Tf). Daraus lässt sich ableiten, dass aufgrund der geringeren Symmetrie der neuen Anionen die Koordinierung der Lithiumkationen deutlich schwächer ausfällt als bei der Vergleichssubstanz LiN(Tf)2. Im dritten Teil dieser Arbeit wurde ein elektrochemisches Messsystem bestehend aus einer temperierbaren Plattform und auswechselbaren Messzellen entwickelt. Die Plattform beinhaltet ein Peltier-Element, das von einem Temperaturregler angesteuert wird. Auf diese Weise ist die schnelle und präzise Einstellung von verschiedenen Temperaturwerten möglich; die Heiz- und Kühlrate beträgt bis zu 60 °C/min, die Temperatur wird auf ±0,1 °C konstant gehalten. Die verschiedenen Messzellen sind für die Verwendung unterschiedlicher Proben ausgelegt, es können schwer- und leichtflüchtige Flüssigkeiten, Gele, Polymere und andere Festelektrolyte wie Glaskeramiken untersucht werden. Die benötigte Probenmenge wurde im Vergleich zu Standard-Messzellen auf ein Minimum reduziert. Für die Flüssigmesszellen werden zwischen 20 µL und 800 µL benötigt, bei den Messzellen für feste Proben sind Mengen im Milligramm-Bereich ausreichend. Um in diesem Messsystem unter Potentialkontrolle arbeiten zu können, wurden Mikroreferenzelektroden speziell für kontaminationssensible elektrochemische Messungen an kleinsten Elektrolytmengen – im Speziellen ionische Flüssigkeiten – hergestellt und auf ihre Potentialstabilität hin getestet. Das interne Redoxsystem besteht dabei aus einem Silberdraht, der in einen Silberelektrolyten eintaucht. Bei der Charakterisierung von ionischen Flüssigkeiten wird dabei idealerweise die gleiche IL und das Silbersalz mit der gleichen Anionensorte als Innenelektrolyt verwendet. Damit bleiben die Silberionen als einzig mögliche Verunreinigung. Anhand von in regelmäßigen zeitlichen Abständen gemessenen Zyklovoltammogrammen an einem IL-basierten Testelektrolyten mit Ferrocen und Cobaltocenium-hexafluorophosphat konnte die Langzeitstabilität der Elektroden gezeigt werden. Die Drift lag unter 20 mV über einen Zeitraum von vier Wochen.

The aim of this work is the identification and the development of techniques allowing the measurement of the complex permittivity of concrete in the frequency range of the geophysical radar or GPR (Ground Penetration Radar). Two typical techniques were developed: a coaxial/cylindrical waveguide cell (50 MHz - 1,6 GHz) and two ended rectangular waveguide probes (spectral bands: [ 4 - 7 GHz ] and [ 7 - 13 GHz ]). These methods presented the advantages that they are broadband and less destructive. In addition, the numerical simulations carried out with a 3D electromagnetic software showed that these techniques presented a great penetration depth, as well as a good sensitivity of measurement. Then, they make it possible to satisfy the Representative Elementary Volume criterion (REV - minimal size of material to have representative measurements). The theoretical study of the probes/cellule required the analysis of the direct and inverse problems. The study of the direct problem allowed the calculation of the reflection coefficient according to the dielectric properties of the material under test. The calculation of the permittivity from the measured reflection coefficient defines the inverse problem. After the design of the measurement devices, the developed softwares have been validated by testing different materials with known permittivity. The measurements carried out on different mixtures showed that the type of the aggregates influence considerably the variation of the permittivity, the maximum size of the aggregates influences the permittivity in the centimetric wave range, and this latter varies linearly according to the compacity., L'objectif de ce mémoire de thèse est l'identification et la mise au point de techniques permettant la mesure de la permittivité complexe des bétons dans le domaine de fréquence de fonctionnement des radar géophysiques. Deux techniques types ont été développées : une cellule en transition linge coaxiale/guide cylindrique (50 MHz – 1,6 GHz) et deux sondes en guide d'onde rectangulaire (bandes spectrales retenues : [4 – 7 GHz] et [7 – 13 GHz]). Outre leurs caractères large bande et peu destructif, des simulations numériques réalisées à l'aide d'un logiciel électromagnétique 3D ont montré que ces techniques présentent les avantages d'avoir une grande profondeur de pénétration (supérieure à 6 cm), ainsi qu'une bonne sensibilité de mesure. Elles permettent alors de satisfaire le critère du Volume Élémentaire Représentatif (VER - taille minimale du matériau pour avoir des mesures représentatives).L'étude théorique des sondes/cellule a nécessité l'analyse des problèmes direct et inverse. L'étude du problème direct permet de calculer le coefficient de réflexion en fonction des propriétés diélectriques du matériau à caractériser. Le calcul de la permittivité à partir du coefficient de réflexion mesuré définit le problème inverse. Après la conception des dispositifs de mesure, les logiciels de dépouillement des données et d'étalonnage ont été validés sur des matériaux étalons.Enfin, Les mesures réalisées sur différents mélanges de béton ont montré que la nature des granulats joue un rôle prépondérant sur la variation de la permittivité, que la taille maximale des granulats influence la permittivité dans le domaine centimétrique, et que cette dernière varie linéairement en fonction de la compacité.

The aim of this work is the identification and the development of techniques allowing the measurement of the complex permittivity of concrete in the frequency range of the geophysical radar or GPR (Ground Penetration Radar). Two typical techniques were developed: a coaxial/cylindrical waveguide cell (50 MHz - 1,6 GHz) and two ended rectangular waveguide probes (spectral bands: [ 4 - 7 GHz ] and [ 7 - 13 GHz ]). These methods presented the advantages that they are broadband and less destructive. In addition, the numerical simulations carried out with a 3D electromagnetic software showed that these techniques presented a great penetration depth, as well as a good sensitivity of measurement. Then, they make it possible to satisfy the Representative Elementary Volume criterion (REV - minimal size of material to have representative measurements). The theoretical study of the probes/cellule required the analysis of the direct and inverse problems. The study of the direct problem allowed the calculation of the reflection coefficient according to the dielectric properties of the material under test. The calculation of the permittivity from the measured reflection coefficient defines the inverse problem. After the design of the measurement devices, the developed softwares have been validated by testing different materials with known permittivity. The measurements carried out on different mixtures showed that the type of the aggregates influence considerably the variation of the permittivity, the maximum size of the aggregates influences the permittivity in the centimetric wave range, and this latter varies linearly according to the compacity.; L'objectif de ce mémoire de thèse est l'identification et la mise au point de techniques permettant la mesure de la permittivité complexe des bétons dans le domaine de fréquence de fonctionnement des radar géophysiques. Deux techniques types ont été développées : une cellule en transition linge coaxiale/guide cylindrique (50 MHz – 1,6 GHz) et deux sondes en guide d'onde rectangulaire (bandes spectrales retenues : [4 – 7 GHz] et [7 – 13 GHz]). Outre leurs caractères large bande et peu destructif, des simulations numériques réalisées à l'aide d'un logiciel électromagnétique 3D ont montré que ces techniques présentent les avantages d'avoir une grande profondeur de pénétration (supérieure à 6 cm), ainsi qu'une bonne sensibilité de mesure. Elles permettent alors de satisfaire le critère du Volume Élémentaire Représentatif (VER - taille minimale du matériau pour avoir des mesures représentatives).L'étude théorique des sondes/cellule a nécessité l'analyse des problèmes direct et inverse. L'étude du problème direct permet de calculer le coefficient de réflexion en fonction des propriétés diélectriques du matériau à caractériser. Le calcul de la permittivité à partir du coefficient de réflexion mesuré définit le problème inverse. Après la conception des dispositifs de mesure, les logiciels de dépouillement des données et d'étalonnage ont été validés sur des matériaux étalons.Enfin, Les mesures réalisées sur différents mélanges de béton ont montré que la nature des granulats joue un rôle prépondérant sur la variation de la permittivité, que la taille maximale des granulats influence la permittivité dans le domaine centimétrique, et que cette dernière varie linéairement en fonction de la compacité.

A new measurement cell for very small quantities of liquid crystals is used for the determination of the complex permittivity of the cyanobenzylidene p' octyloxyaniline (CBOOA). The dielectric behaviour in the nematic and smectic-A phase is given as a function of an applied electric field (static and alternative) as well as of a magnetic one within a large frequency and temperature range Utilisation d'une nouvelle cellule pour les mesures dielectriques sur de faibles quantites de cristal liquide. Application a la cyanobenzylidene octyloxyaniline: permittivite complexe en champ electrique continu ou alternatif, sous champ magnetique, dans un grand intervalle de frequences et de temperatures en phase nematique et smectique

A cell for measurement electrical parameters of tooth is presented. Finite Element Method is used for calculation of current density distribution. The simulations show that even half of the total current can flow outside the examined tooth. The presented results strongly depend on the relation of electric parameters of tooth to corresponding ones of the cell material.