Flow cell for operando X-ray photon-in-photon-out studies on photo-electrochemical thin film devices.

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 X­ray 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' X­ray 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 open­circuit, to detect X­ray 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.

Aspectos hematológicos de catetos (Tayassu tajacu) mantidos em cativeiro / Hematologic aspects of collared peccary (Tayassu tajacu) in captivity

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 por cento. 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<0,05). Ao se comparar animais adultos com jovens, observou-se diferença no valor do volume globular (p<0,05) e uma relação neutrófilo segmentado/linfócito inversa, com predomínio dos neutrófilos segmentados sobre os linfócitos nos animais jovens. Em relação à mensuração das células observou-se semelhança ao descrito para vacas, gato e cavalos. Estes resultados poderão subsidiar novos estudos, assim como futuras interpretações em animais hígidos ou doentes, com atenção às condições de manejo, clima e principalmente forma de contenção e tipo de população em que os estudos são realizados.

The aim of the study was to determine the blood values for the Tayassu tajacu (collared peccary) in captivity. Twenty-six collared peccary, being twenty-one adults (13 males and 8 females) and five young (3 males and 2 females) were maintained at the Experimental Farm of Almada and the Laboratory of Applied Ethology, belonging to the University Estadual of the Santa Cruz, Ilheus, Bahia, Brazil. Blood samples were collected from the cephalic vein to perform the complete blood count. Statistical analysis was performed using the Student's t-test, with a significance level of 95 percent. There was no significant difference from animals maintained in stalls or pickets, however there was a higher value of total plasma protein in males (p<0,05). When comparing adult animals with young animals, we observed differences in the packed cell volume (p<0,05) and a reverse relationship between mature neutrophils/lymphocytes, with a predominance of mature neutrophils (46,8 percent) on lymphocytes (45 percent) for young animals. Regarding the measurement of the cells was observed similarity to that described for cows, cats and horses. These results could support new studies, as well as future interpretations in healthy or sick animals, with attention how to handle the management of animals, weather and especially the form of restraint and type of population in what these studies are conducted.

Experimental determination of the far-infrared optical properties of biological matter in aqueous solution.

Experimental details are given of how to reliably measure theoptical properties of aqueous solutions in the far-infraredspectral range using a Fourier transform spectrometer. We discussthe analysis of reflection and transmission data in order toobtain the refractive index and the absorption coefficient. Someresults on water and biological systems are presented.