Influence of Chronic Exposure to Treated Sewage Effluent on the Distribution of White Blood Cell Populations in Rainbow Trout (Oncorhynchus mykiss) Spleen

Impairment of immune function in aquatic animals has been proposed as a possible consequence of low-level contamination of surface waters with anthropogenic substances such as through the discharge of wastewater into rivers, lakes, and oceans. The study at hand investigated the effects of chronic (32 weeks) exposure to sewage treatment plant (STP) effluent on the prevalence and distribution of different leucocyte populations in spleen samples of rainbow trout (Oncorhynchus mykiss). To simulate an infection, fish were injected intraperitoneally (ip) with inactivated Aeromonas salmonicida salmonicida, 6 weeks prior to the termination of the experiment. Immunohistological analysis revealed a marked decrease in thrombocyte numbers, an increase of monocytes, altered distribution of B-cells, and higher surface immunoglobulin expression, as well as activation of MHC class II expression in the spleen after exposure to 15% (v/v) effluent. The most prominent finding of the present study, however, was the occurrence of intraplasmatic deposits or inclusions with strong autofluorescence in spleen sections from effluent-exposed trout. In addition to effluent effects, injection of trout with A. salmonicida stimulated infiltration of monocytes, increased staining intensity on thrombocytes, and enhanced MHC class I expression in larger leucocytes surrounding melanomacrophage centres. In general, the current study demonstrates a marked, potentially adverse effect of STP effluent on spleen leucocytes and on the integrity of spleen tissue. The observed response suggests a constant unspecific stimulation of different leucocyte populations and is reminiscent of chronic inflammatio

Method development for non-routine compound specific stable isotope analysis (CSIA) of light elements

Multi-dimensional compound specific stable isotope analysis (CSIA) is a promising new analytical approach wherein changes in isotope ratios are measured across multiple elements within a given compound, shedding light on reaction mechanisms and allowing for the identification and characterisation of the origin, distribution, conversion, and degradation of organic chemicals. Thus far, routine methods are available for measurements of carbon and hydrogen isotopes; however, in order to fully exploit the potential of multi-dimensional CSIA, new approaches are needed for halogen, oxygen, and hydrogen stable isotope analysis in heteroatom-bearing compounds. In order to facilitate such an expansion, the work described in this thesis was aimed at the development of methods for CSIA for rarely-analysed chlorine and oxygen stable isotopes, as well as to improve hydrogen stable isotope analysis for halogenated compounds, which were previously inaccessible. The presented approaches used high temperature conversion (HTC, >1200 °C) to generate HCl, CO, and H2 analyte gas from organic compounds online after gas chromatographic (GC) separation. For respective stable isotope ratio determination of those analyte gases, the GC-HTC interface was interlinked with a gas analyser (qMS) and later an isotope ratio mass spectrometer (IRMS). For conversion characterisation an organic mass spectrometer (IonTrap MS) was used in parallel at the end of the tested reactors. Chlorine stable isotope analysis using GC-HTC-IRMS was achieved for a set of chlorinated compounds. Hydrogen stable isotope analysis of heteroatom-bearing (Cl, N, S) substances was improved fundamentally by providing chromium powder in the reactor. The developed novel GC-Cr/HTC-IRMS method was successfully validated and implemented for hydrogen CSIA. Investigations of the commercially available reactor for oxygen GC-HTC-IRMS showed undesired by-products and HTC processes which inhibited reproducible and accurate CSIA of volatile organic compounds. For future method development and to identify and quantify interfering by-products in GC-HTC-IRMS in general, an evaluation strategy is proposed. In summary, GC-HTC-IRMS approaches were investigated and successfully applied to extend the existing repertoire of non-routine CSIA methods for chlorine, hydrogen and oxygen stable isotopes.Die Aussagekraft der mehrdimensionalen komponentenspezifischen stabilen Isotopenanalyse (CSIA) hinsichtlich der Identifikation und Charakterisierung von Ursprung, Verteilung, Umwandlung und Abbau von organischen Chemikalien ist um ein Vielfaches stärker als die der herkömmlichen CSIA nur eines Elementes. Um dieses Potential auszuschöpfen, sind neben den routinemäßig zugänglichen Isotopen (13C, 2H) neue Methoden für Halogen-, aber auch Sauerstoff- und Wasserstoff-Isotope in Heteroverbindungen notwendig. Ziel dieser Arbeit war die Methodenentwicklung für die CSIA von bisher nur vereinzelt untersuchten Elementen Chlor und Sauerstoff (37Cl, 18O), sowie für Wasserstoff (2H) an halogenierten Verbindungen, die mit existierenden Methoden nicht oder nur eingeschränkt messbar waren. Im Rahmen der vorgelegten Arbeit wurde die Hochtemperaturumsetzung (HTC, >1200 °C) zur Erzeugung von HCl-, CO- und H2-Analyse-Gasen aus organischen Verbindungen direkt im Anschluss (online) an die gaschromatographische Trennung (GC-HTC) genutzt. Zur Bestimmung der Isotopenverhältnisse an diesen Analyse-Gasen wurde das GC-HTC-Interface zuerst mit einem Restgasanalysator (qMS) und anschließend mit einem Isotopenverhältnis-Massenspektrometer (IRMS) gekoppelt. Für die Charakterisierung der Umsetzung wurde am Ausgang des jeweiligen Reaktors ein paralleles organisches Massenspektrometer (IonTrap MS) verwendet. Dieser GC-HTC-IRMS Ansatz konnte für die Chlorisotopenanalyse am HCl verwirklicht und für verschiedene chlorierte Verbindungen eingesetzt werden. Durch die zusätzliche Verwendung von Chrommetall im Reaktor konnte die Wasserstoffisotopenanalyse mittels GC-Cr/HTC-IRMS für die Messung verschiedener heteroatomhaltiger (Cl, N, S) Verbindungen erfolgreich validiert und etabliert werden. Ferner zeigten die Untersuchungen des kommerziell verfügbaren HTC Reaktors für die Sauerstoffisotopenanalyse, dass unerwünschte Nebenprodukte und versteckte zusätzliche Sauerstoffquellen eine reproduzierbare und akkurate GC-HTC-IRMS Bestimmung erschweren. Es wurde eine Evaluierungsstrategie basierend auf Methoden zur Identifizierung und Quantifizierung störender Nebenprodukte und Prozesse entwickelt, die in Zukunft auch für andere GC-HTC-IRMS Methodenentwicklungen anwendbar ist. In der vorgelegten Arbeit wurden GC-HTC-IRMS Methoden zur Bestimmung der Halogen-, Wasserstoff- und Sauerstoff-Isotopenverhältnisse untersucht und erfolgreich zur Erweiterung der CSIA heteroatom-haltiger organischer Verbindungen genutzt

Effect of ozonation on the removal of cyanobacterial toxins during drinking water treatment.

Water treatment plants faced with toxic cyanobacteria have to be able to remove cyanotoxins from raw water. In this study we investigated the efficacy of ozonation coupled with various filtration steps under different cyanobacterial bloom conditions. Cyanobacteria were ozonated in a laboratory-scale batch reactor modeled on a system used by a modern waterworks, with subsequent activated carbon and sand filtration steps. The presence of cyanobacterial toxins (microcystins) was determined using the protein phosphatase inhibition assay. We found that ozone concentrations of at least 1.5 mg/L were required to provide enough oxidation potential to destroy the toxin present in 5 X 10(5 )Microcystis aeruginosa cells/mL [total organic carbon (TOC), 1.56 mg/L]. High raw water TOC was shown to reduce the efficiency of free toxin oxidation and destruction. In addition, ozonation of raw waters containing high cyanobacteria cell densities will result in cell lysis and liberation of intracellular toxins. Thus, we emphasize that only regular and simultaneous monitoring of TOC/dissolved organic carbon and cyanobacterial cell densities, in conjunction with online residual O(3) concentration determination and efficient filtration steps, can ensure the provision of safe drinking water from surface waters contaminated with toxic cyanobacterial blooms

Weak Localization Effect in Superconductors by Radiation Damage

Large reductions of the superconducting transition temperature $T_{c}$ and the accompanying loss of the thermal electrical resistivity (electron-phonon interaction) due to radiation damage have been observed for several A15 compounds, Chevrel phase and Ternary superconductors, and $\rm{NbSe_{2}}$ in the high fluence regime. We examine these behaviors based on the recent theory of weak localization effect in superconductors. We find a good fitting to the experimental data. In particular, weak localization correction to the phonon-mediated interaction is derived from the density correlation function. It is shown that weak localization has a strong influence on both the phonon-mediated interaction and the electron-phonon interaction, which leads to the universal correlation of $T_{c}$ and resistance ratio.Comment: 16 pages plus 3 figures, revtex, 76 references, For more information, Plesse see http://www.fen.bilkent.edu.tr/~yjki

I ought to put down that phone but I phub nevertheless: Examining the predictors of phubbing behavior

Smartphones are ubiquitous and frequently used in copresent interactions. This behavior is often seen as inappropriate and thus has been termed phubbing, compromising the words “phone” and “snubbing.” Although being a worldwide phenomenon, little is known about what predicts phubbing behavior in the first place. Drawing on injunctive norms (i.e., what ought to be done), the study’s aim was to shed light on the relationship between mobile phone norms (MPN) and phubbing behavior. Furthermore, the role of being permanently online and permanently connected (POPC) and fear of missing out (FOMO), reflecting approach and avoidance orientations, respectively, as additional predictors and moderators was investigated. As expected, the findings of an online survey (N = 278) supported the assumption that MPN were negatively related to phubbing behavior. Moreover, results showed that both FOMO and POPC were significantly positively connected to phubbing behavior but did not play significant moderating roles concerning the norm–phubbing relationship

Hole-mediated photoredox catalysis: Tris(: P-substituted)biarylaminium radical cations as tunable, precomplexing and potent photooxidants

As a combination of visible light photoredox catalysis and synthetic organic electrochemistry, electrochemically-mediated photoredox catalysis emerged as a powerful synthetic technique in recent years, overcoming fundamental limitations of electrochemistry and photoredox catalysis in the single electron transfer activation of small organic molecules. Herein we report a tunable class of electroactivated photoredox catalyst, tri(para-substituted)biarylamines, that become superoxidants in their photoexcited states even able to oxidize molecules beyond the solvent window limits of cyclic voltammetry (such as polyfluorobenzene and trifluorotoluene). Furthermore, we demonstrate that precomplexation not only permits the excited state photochemistry of tris(para-substituted)biarylaminium cations to overcome picosecond lifetime, but enables and rationalizes the surprising photochemistry of their higher-order doublet (Dn) excited states, unlocking extremely high oxidative potentials (up to a record-breaking ∼+4.4 V vs. SCE). This journal i

Statistical processing and visualization of the medical data

The aim of the research is to consider basic concepts of descriptive statistics and to show basic histograms for the medical data

Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb2+

DNA sequences with guanine repeats can form G-quartets that adopt G-quadruplex structures in the presence of specific metal ions. Using circular dichroism (CD) and ultraviolet-visible (UV–Vis) spectroscopy, we determined the spectral characteristics and the overall conformation of a G-quadruplex of PS2.M with an oligonucleotide sequence, d(GTG3TAG3CG3TTG2). UV-melting curves demonstrate that the Pb2+-induced G-quadruplex formed unimolecularly and the highest melting temperature (Tm) is 72°C. The analysis of the UV titration results reveals that the binding stoichiometry of Pb2+ ions to PS2.M is two, suggesting that the Pb2+ ions coordinate between adjacent G-quartets. Binding of ions to G-rich DNA is a complex multiple-pathway process, which is strongly affected by the type of the cations. Kinetic studies suggest that the Pb2+-induced folding of PS2.M to G-quadruplex probably proceeds through a three-step pathway involving two intermediates. Structural transition occurs after adding Pb(NO3)2 to the Na+- or K+-induced G-quadruplexes, which may be attributed to the replacement of Na+ or K+ by Pb2+ ions and the generation of a more compact Pb2+–PS2.M structure. Comparison of the relaxation times shows that the Na+→Pb2+ exchange is more facile than the K+→Pb2+ exchange process, and the mechanisms for these processes are proposed

Hydrogen‐Bond‐Modulated Nucleofugality of SeIII Species to Enable Photoredox‐Catalytic Semipinacol Manifolds

Chemical bond activations mediated by H-bond interactions involving highly electronegative elements such as nitrogen and oxygen are powerful tactics in modern catalysis research. On the contrary, kindred catalytic regimes in which heavier, less electronegative elements such as selenium engage in H-bond interactions to co-activate C−Se σ-bonds under oxidative conditions are elusive. Traditional strategies to enhance the nucleofugality of selenium residues predicate on the oxidative addition of electrophiles onto SeII-centers, which entails the elimination of the resulting SeIV moieties. Catalytic procedures in which SeIV nucleofuges are substituted rather than eliminated are very rare and, so far, not applicable to carbon-carbon bond formations. In this study, we introduce an unprecedented combination of O−H⋅⋅⋅Se H-bond interactions and single electron oxidation to catalytically generate SeIII nucleofuges that allow for the formation of new C−C σ-bonds by means of a type I semipinacol process in high yields and excellent selectivity