A Novel Application for Low Frequency Electrochemical Impedance Spectroscopy as an Online Process Monitoring Tool for Viable Cell Concentrations.

New approaches in process monitoring during industrial fermentations are not only limited to classical pH, dO2 and offgas analysis, but use different in situ and online sensors based on different physical principles to determine biomass, product quality, lysis and far more. One of the very important approaches is the in situ accessibility of viable cell concentration (VCC). This knowledge provides increased efficiency in monitoring and controlling strategies during cultivations. Electrochemical impedance spectroscopy-EIS-is used to monitor biomass in a fermentation of E. coli BL21(DE3), producing a recombinant protein using a fed batch-based approach. Increases in the double layer capacitance (Cdl), determined at frequencies below 1 kHz, are proportional to the increase of biomass in the batch and fed batch phase, monitored in offline and online modes for different cultivations. A good correlation of Cdl with cell density is found and in order to get an appropriate verification of this method, different state-of-the-art biomass measurements are performed and compared. Since measurements in this frequency range are largely determined by the double layer region between the electrode and media, rather minor interferences with process parameters (aeration, stirring) are to be expected. It is shown that impedance spectroscopy at low frequencies is a powerful tool for cultivation monitoring.

Observer-based H∞ fuzzy fault-tolerant switching control for ship course tracking with steering machine fault detection.

To enhance the robustness of ship autopilot (SA) system with nonlinear dynamics, unmeasured states, and unknown steering machine fault, an observer-based H∞ fuzzy fault-tolerant switching control for ship course tracking is proposed. Firstly, a global Takagi-Sugeno (T-S) fuzzy nonlinear ship autopilot (NSA) is developed with full consideration of ship steering characteristics. And the actual navigation data collected from a real ship are used to verify the reasonableness and feasibility of NSA model. Then, virtual fuzzy observers (VFOs) for both fault-free and faulty systems are proposed to estimate the unmeasured states and unknown fault simultaneously, and compensate for the faulty system by using the fault estimates. Accordingly, the VFO-based H∞ robust controller (VFO-HRC) and fault-tolerant controller (VFO-HFTC) are designed. Subsequently, a smoothed Z-score-based fault detection and alarm (FDA) is developed to provide switching signals for which the controller and its corresponding observer should be invoked. Finally, simulation results on the "Yulong" ship demonstrate the effectiveness of the developed control method.

Macroclimatic conditions as main drivers for symbiotic association patterns in lecideoid lichens along the Transantarctic Mountains, Ross Sea region, Antarctica.

Lecideoid lichens as dominant vegetation-forming organisms in the climatically harsh areas of the southern part of continental Antarctica show clear preferences in relation to environmental conditions (i.e. macroclimate). 306 lichen samples were included in the study, collected along the Ross Sea coast (78°S-85.5°S) at six climatically different sites. The species compositions as well as the associations of their two dominant symbiotic partners (myco- and photobiont) were set in context with environmental conditions along the latitudinal gradient. Diversity values were nonlinear with respect to latitude, with the highest alpha diversity in the milder areas of the McMurdo Dry Valleys (78°S) and the most southern areas (Durham Point, 85.5°S; Garden Spur, 84.5°S), and lowest in the especially arid and cold Darwin Area (~ 79.8°S). Furthermore, the specificity of mycobiont species towards their photobionts decreased under more severe climate conditions. The generalist lichen species Lecanora fuscobrunnea and Lecidea cancriformis were present in almost all habitats, but were dominant in climatically extreme areas. Carbonea vorticosa, Lecidella greenii and Rhizoplaca macleanii were confined to milder areas. In summary, the macroclimate is considered to be the main driver of species distribution, making certain species useful as bioindicators of climate conditions and, consequently, for assessing the consequences of climate change.

Alterations in secondary metabolism of aposymbiotically grown mycobionts of Xanthoria elegans and cultured resynthesis stages.

HPLC analyses of Xanthoria elegans cultivated on different media and either aposymbiontically or with its photobiont revealed that the carbon source and the presence of the algal partner have an impact on the secondary metabolism of the mycobiont. The aposymbiotically (without photobiont) grown mycobiont contained up to 70% more of the main compounds in its thallus than in resynthesis stage. Although this is speculative, the induction of the polyketide pathway may be a feedback mechanism to the absence of the photobiont. All cultures produce a variety of substances which were not detectable in the voucher specimen. Besides physcion (the major substance), we were able to identify emodin as well as physcion-bisanthrone, teloschistin monoacetate and derivatives. A strong inducible effect on the production of physcion, physcion-bisanthrone and on their precursors and derivatives was found for mannitol. By contrast, supplementation of ribitol had negligible effects, if any, on polyketide quantities although it is the main carbon source for the mycobiont in free-living lichens with Trebouxia photobiont.

A solid oxide photoelectrochemical cell with UV light-driven oxygen storage in mixed conducting electrodes.

A single crystalline SrTiO3 working electrode in a zirconia-based solid oxide electrochemical cell is illuminated by UV light at temperatures of 360-460 °C. In addition to photovoltaic effects, this leads to the build-up of a battery-type voltage up to more than 300 mV. After switching off UV light, this voltage only slowly decays. It is caused by UV-induced oxygen incorporation into the mixed conducting working electrode and thus by changes of the oxygen stoichiometry δ in SrTiO3-δ under UV illumination. These changes of the oxygen content could be followed in time-dependent voltage measurements and also manifest themselves in time-dependent resistance changes during and after UV illumination. Discharge currents measured after UV illumination reveal that a large fraction of the existing oxygen vacancies in SrTiO3 become filled under UV light. Additional measurements on cells with TiO2 thin film electrodes show the broader applicability of this novel approach for transforming light into chemical energy and thus the feasibility of solid oxide photoelectrochemical cells (SOPECs) in general and of a "light-charged oxygen battery" in particular.

Nab-paclitaxel as alternative treatment regimen in advanced cholangiocellular carcinoma.

BACKGROUND: Advanced cholangiocellular carcinoma has a poor prognosis with limited therapeutic options. Nab-paclitaxel has recently been described to be beneficial in metastatic pancreatic cancer improving overall and progression free survival (PFS). The potential antitumor activity of nab-paclitaxel in cholangiocellular carcinoma is hitherto unknown. METHODS: We retrospectively analyzed an institutional cholangiocellular carcinoma registry to determine the potential biological activity of nab-paclitaxel in advanced intrahepatic cholangiocellular carcinoma. Disease control rate (DCR), PFS and overall survival (OS) upon nab-paclitaxel based treatment, after failure of platinum-containing first-line combination chemotherapy, was assessed. RESULTS: Twelve patients were identified. Five of 12 patients (42%) received nab-paclitaxel as second line, and 7 patients (56%) as third-line treatment. The objective DCR with nab-paclitaxel was 83% (10/12 patients). One patient had a complete remission (CR), two patients had a partial remission (PR) and 7 patients had stable disease (SD). Disease was rated progressive in two patients. In all 12 patients receiving nab-paclitaxel the median time to progression was 6 months (range, 2.1-19.5 months). Median OS after initiation of nab-paclitaxel treatment was 9 months (2.1-28.4 months). The median time of survival after diagnosis of advanced disease was 21.5 months, whereby 3 patients were alive at the date of censoring (04/01/2015). CONCLUSIONS: This is the first report suggesting substantial antitumor activity of nab-paclitaxel in advanced cholangiocellular carcinoma. In this small series, nab-paclitaxel based salvage chemotherapy appears to have a biological activity by controlling the disease and positively affecting survival. Randomized trials in this disease entity and subgroup of patients are urged.

High photobiont diversity in the common European soil crust lichen Psora decipiens.

The genetic diversity of green algal photobionts (chlorobionts) in soil crust forming lichens was studied as part of the SCIN-project (Soil Crust InterNational). A total of 64 lichen samples were collected from four different sites along latitudinal and altitudinal gradients in Europe (Tabernas/Spain; Hochtor-Großglockner/Austria; Gynge Alvar/Sweden; Ruine Homburg/Germany). The dominant lichen species at all four sites was Psora decipiens, often occurring with Buellia elegans, Fulgensia bracteata, F. fulgens and Peltigera rufescens. Genetic identification of chlorobionts was carried out using the nuclear marker (nrITS) and a chloroplast marker (psbL-J). We found P. decipiens to be associated with several different species of Trebouxia and Asterochloris, although previously described to only have Asterochloris sp. The phylogenetic analyses revealed a high chlorobiont diversity with 12 well supported clades, including Trebouxia asymmetrica, T. jamesii, T. impressa and other, as yet taxonomically unidentified clades (Trebouxia sp. URa1-4, T. sp. URa6, T. sp. URa7-13). Additionally, five clades of Asterochloris were identified (A. magna, A. sp. URa14 -17). Most of the chlorobiont species appeared to be cosmopolitan, but five clades were unevenly distributed between the sampling sites with only Trebouxia being found in the warm and dry Spanish habitats and combinations of Trebouxia and Asterochloris in the cooler and more humid habitats. The wide range of chlorobiont species might contribute to the observed domination of P. decipiens at all four research sites of the SCIN project which range from a desert in Spain to an alpine site in the Alps of Austria.

A transcribed polyketide synthase gene from Xanthoria elegans.

We characterize the transcript of a polyketide synthase gene (PKS) from the cultured mycobiont of Xanthoria elegans (XePKS1) using SMART-rapid amplification of cDNA ends (RACE) cDNA synthesis. Sequence analysis of the cloned cDNA reveals an open reading frame of 2144 amino acid residues. It contains features of a non-reducing fungal type I PKS with an N-terminal starter unit: acyl carrier protein (ACP) transacetylase domain, ketosynthase, acyltransferase, two acyl carrier protein domains, and a thioesterase domain. XePKS1 was the only paralogue detected in the cDNA and the genomic DNA of the cultured X. elegans mycobiont by using a degenerate PCR approach targeted at the conserved regions of non-reducing type I PKS genes. The hypothetical protein is phylogenetically related to genes that are basal to a clade of dihydroxynaphthalene synthases (non-reducing clade II) and anthraquinone type synthases of non-lichenized fungi (non-reducing clade I). According to hplc and tlc analyses, the cultured mycobiont exclusively produced anthraquinones and its precursors. Therefore, we discuss whether the characterized paralogue is involved in anthraquinone production, which raises the possibility of a paraphyletic origin of lichen anthraquinone biosynthesis. The cDNA of XePKS1 was the first full-length coding sequence of a lichen PKS to be published. This proves SMART RACE to be a suitable tool for obtaining full-length coding sequences of genes from environmental samples and organisms, which are hardly amenable to standard molecular approaches or genomic sequencing.

Production and bioactivity of common lichen metabolites as exemplified by Heterodea muelleri (Hampe) Nyl.

Based on results of a former study in 2005, this investigation aimed at quantifying UV- and cold temperature stress-induced changes within the secondary metabolite production of the cultured mycobiont of the lichen Heterodea muelleri (Hampe) Nyl. The chemical profiles of the mycobiont cultures and the lichen thallus were determined by high-performance liquid chromatography (HPLC) and thin layer chromatography (TLC) analyses. The voucher specimen of H. muelleri produced diffractaic acid as a major polyketide and barbatic acid as a satellite compound, whereas the untreated mycobiont did not contain any detectable secondary metabolites. While UV-C stress caused a general increase in substance formation, cold temperature stress resulted in a strong activation of barbatic acid biosynthesis. A further series of experiments focused on the effect of diffractaic and barbatic acids on the growth of the symbiotic photobiont Trebouxia jamesii; usnic acid was similarly tested. Pure substances were obtained from mycobiont cultures by performing preparative TLC. A determined quantity of algae was incubated on BBM plates that contained three different concentrations of the pure lichen metabolites. The growth of the photobionts was monitored over a period of 1 mo to evaluate the impact of each substance on the cultured algae. While diffractaic and usnic acid had no noticeable effect, barbatic acid strongly inhibited algal growth and resulted in cell death.