Laser controlled cycloaddition and reversion of crossdimers

To treat cataract, the major cause for blindness, the original eye lenses are removed and artificial lenses are implanted. With this procedure, the side effect of secondary cataract has become of interest to research. The treatment thereof calls for the development of a molecular integrated and covalently bound photolinker system for the controlled release of cytostatica. To load the polymeric intraocular lens, crossdimers of the photolinker coumarin together with the antimetabolite 5-fluorouracil are synthesized. After incorporation in the lens, the specific release via cycloreversion then is best realized with a two photon process which offers high spatial resolution, and which uses visual light to pass the cornea. The backbone of this work is the light driven, intermolecular and coumarin based crossdimerization and its reversion. To achieve this goal, the options given for photoreactions, like set up, substrates, and excitation are considered and their variables are evaluated. The choice of photolinker is narrowed down and a comparison between these absorbing substrates provided by kinetic measurements. A list of possible molecule types of the non-absorbing reaction partner for the crossdimerization is given, by which a huge variety of crossdimers can be build up. The commonly used lamp based light sources such as a Rayonet reactor are compared to the novel favored laser system. The sun is also utilized to project a large scale, energetically economic process. The laser, as a new tool for molecule synthesis, exhibits improvements to cycloaddition reactions in a number of experiments. Additives like sensitizers and triplet promoters are shown to be unnecessary with this high energy illumination. The laser fueled set up is analyzed and the photon distribution, together with the photon flux, is determined to be crucial. With parameters attuned to the lifetime of the excited state, the diffusion controlled dimerization reaction can be controlled and steered towards the principal generation of crossdimer. The reversibility of the dimerization reaction caused both by heat and light is demonstrated. Thermal cleavage is used in addition to laser synthesis in the specialization towards exclusive crossdimer synthesis. Light is primarily used in the customary laser based two photon absorption for specific single and two bond cleavage. Hereby the ever more popular two photon cycloreversion is measured of individual stereoisomers. All methods, developed for the dimer generation, belong to the general concept for the extended application of photoreaction in synthesis. Additional examples in form of a sequential photoreaction and photoremovable protective groups are presented accordingly

Seawater desalination in micro grids: an integrated planning approach

Background: Islands often depend on the import of fossil fuels for power generation. Due to the combined effect of high oil prices and transportation costs, energy supply systems based on renewable energies are already able to compete successfully with fossil fuel systems for a number of these islands. Depending on local and regional conditions, not only energy supply is a challenge, but also the finding of a reliable supply of water. A promising alternative to freshwater shipments is seawater desalination. Desalination processes can act as a flexible load whenever excess electricity generated by renewable sources is present. Methods: Numerical simulations of combined energy and water supply systems for the Caribbean island Petite Martinique, Grenada, are accomplished. Considering renewable energy sources like wind and solar radiation, energy storage technologies, and desalination processes, various scenarios are introduced and simulated, and the results are compared. Results: An extension of the current energy supply system with renewable energy technologies reduces power generation costs by approximately 40%. The excess energy generated by renewables can supply a significant share of a desalination plant’s energy demand. The levelized costs of electricity and water show that the integration of desalination as a deferrable load is beneficial to the considered micro grid. Conclusions: The implementation of renewable energy generation and desalination as deferrable load is recommendable in Petite Martinique. Possible refinancing strategies depending on the combination of different electricity and water tariffs can be derived and applied to similar business cases in remote regions

Effect of an herbal extract of sideritis scardica and B-vitamins on cognitive performance under stress: A pilot study

Chronic stress can impair cognitive functions including learning and memory. The current study investigated the reduction of (mental) stress and improvement of stress tolerance in 64 healthy men and women after six weeks intake of a dietary supplement containing an extract of Sideritis scardica and selected B-vitamins. Mental performance and visual attention were measured by Trail-Making Test (TMT) and Colour-Word-Test (CWT)before/after an acute stress stimulus (noise, CW-Interference). TMT improved upon product intake. The CWT reaction time accelerated upon product intake in situations of CW-Congruence (overall) (p=0.014), CW-conflict (overall) (p=0.024), CW-conflict (with noise) (p=0.001), CW-Congruence (without noise) (p=0.004) and CW-conflict (without noise) (p=0.017).CWT-changes upon product intake, differentiated for noise and CW-interference, showed (i) a bisection of CW-interference-related impairment of the reaction time in the presence of noise from 27 ms to 13.5 ms, (ii) a bisection of noise-related impairment of the reaction time in the presence of CW-conflict from 34 ms to 17 ms, (iii) an improvement of the impairment of the reaction time due to combined stress (noise plus CW-conflict) by 14.5 ms from 66 ms to 51.5 ms, (iv) despite of the improvement of the reaction time, no increase of the error rate. Safety blood parameters and the reporting of no adverse events argue for the product’s safety. These results may be relevant for persons solving cognitive tasks under conflict and/or noise (e.g. open-plan offices or car-driving) andsupport that the tested product alleviatesstress-induced impairment of executive functioning (working memory, cognitive flexibility, controlled behavioural inhibition).Schaper & Brümmer GmbH & Co. KG, Salzgitter, German

Effect of an herbal extract of Sideritis scardica and B-vitamins on cognitive performance under stress: a pilot study

Chronic stress can impair cognitive functions including learning and memory. The current study investigated the reduction of (mental) stress and improvement of stress tolerance in 64 healthy men and women after six weeks intake of a dietary supplement containing an extract of Sideritis scardica and selected B-vitamins.Mental performance and visual attention were measured by Trail-Making Test (TMT) and Colour-Word-Test (CWT) before/after an acute stress stimulus (noise, CW-Interference).TMT improved upon product intake. The CWT reaction time accelerated upon product intake in situations of CW-Congruence (overall) (p=0.014), CW-conflict (overall) (p=0.024), CW-conflict (with noise) (p=0.001), CW-Congruence (without noise) (p=0.004) and CW-conflict (without noise) (p=0.017). CWT-changes upon product intake, differentiated for noise and CW-interference, showed (i) a bisection of CW-interference-related impairment of the reaction time in the presence of noise from 27 ms to 13.5 ms, (ii) a bisection of noise-related impairment of the reaction time in the presence of CW-conflict from 34 ms to 17 ms, (iii) an improvement of the impairment of the reaction time due to combined stress (noise plus CW-conflict) by 14.5 ms from 66 ms to 51.5 ms, (iv) despite of the improvement of the reaction time, no increase of the error rate. Safety blood parameters and the reporting of no adverse events argue for the product’s safety.These results may be relevant for persons solving cognitive tasks under conflict and/or noise (e.g. open-plan offices or car-driving) and support that the tested product alleviates stress-induced impairment of executive functioning (working memory, cognitive flexibility, controlled behavioural inhibition)

A Helminth Protease Inhibitor Modulates the Lipopolysaccharide-Induced Proinflammatory Phenotype of Microglia in vitro

Objective: The aim of this study was to examine whether the natural protease inhibitor Av-cystatin (rAv17) of the parasitic nematode Acanthocheilonema viteae exerts anti-inflammatory effects in an in vitro model of lipopolysaccharide (LPS)-activated microglia. Methods: Primary microglia were harvested from the brains of 2-day-old Wistar rats and cultured with or without rAv17 (250 nM). After 6 and 24 h the release of nitric oxide (Griess reagent) and TNF-α (ELISA) was measured in the supernatant. Real-time PCR was performed after 2, 6 and 24 h of culture to measure the mRNA expression of IL-1β, IL-6, TNF-α, COX-2, iNOS and IL-10. To address the involved signaling pathways, nuclear NF-ĸB translocation was visualized by immunocytochemistry. Morphological changes of microglia were analyzed by Coomassie blue staining. Differences between groups were calculated using one-way ANOVA with Bonferroni's post hoc test. Results: Morphological analysis indicated that LPS-induced microglial transformation towards an amoeboid morphology is inhibited by rAv17. Av-cystatin caused a time-dependent downregulation of proinflammatory cytokines, iNOS and COX-2 mRNA expression, respectively. This was paralleled by an upregulated expression of IL-10 in resting as well as in LPS-stimulated microglia. Av-cystatin reduced the release of NO and TNF-α in the culture supernatant. Immunocytochemical staining demonstrated an attenuated translocation of NF-ĸB by Av-cystatin in response to LPS. In addition, Western blot analysis revealed a rAv17-dependent reduction of the LPS-induced ERK1/2-pathway activation. Conclusion: The parasite-derived secretion product Av-cystatin inhibits proinflammatory mechanisms of LPS-induced microglia with IL-10, a potential key mediator.Peer Reviewe

Second Data Science Symposium at AWI

The second Data Science Symposium at AWI gathered several data science related talks from AWI, GEOMAR and HZG

Recreational and occupational field exposure to freshwater cyanobacteria – a review of anecdotal and case reports, epidemiological studies and the challenges for epidemiologic assessment

Cyanobacteria are common inhabitants of freshwater lakes and reservoirs throughout the world. Under favourable conditions, certain cyanobacteria can dominate the phytoplankton within a waterbody and form nuisance blooms. Case reports and anecdotal references dating from 1949 describe a range of illnesses associated with recreational exposure to cyanobacteria: hay fever-like symptoms, pruritic skin rashes and gastro-intestinal symptoms are most frequently reported. Some papers give convincing descriptions of allergic reactions while others describe more serious acute illnesses, with symptoms such as severe headache, pneumonia, fever, myalgia, vertigo and blistering in the mouth. A coroner in the United States found that a teenage boy died as a result of accidentally ingesting a neurotoxic cyanotoxin from a golf course pond. This death is the first recorded human fatality attributed to recreational exposure to cyanobacteria, although uncertainties surround the forensic identification of the suspected cyanotoxin in this case. We systematically reviewed the literature on recreational exposure to freshwater cyanobacteria. Epidemiological data are limited, with six studies conducted since 1990. Statistically significant increases in symptoms were reported in individuals exposed to cyanobacteria compared to unexposed counterparts in two Australian cohort studies, though minor morbidity appeared to be the main finding. The four other small studies (three from the UK, one Australian) did not report any significant association. However, the potential for serious injury or death remains, as freshwater cyanobacteria under bloom conditions are capable of producing potent toxins that cause specific and severe dysfunction to hepatic or central nervous systems. The exposure route for these toxins is oral, from ingestion of recreational water, and possibly by inhalation. A range of freshwater microbial agents may cause acute conditions that present with features that resemble illnesses attributed to contact with cyanobacteria and, conversely, acute illness resulting from exposure to cyanobacteria or cyanotoxins in recreational waters could be misdiagnosed. Accurately assessing exposure to cyanobacteria in recreational waters is difficult and unreliable at present, as specific biomarkers are unavailable. However, diagnosis of cyanobacteria-related illness should be considered for individuals presenting with acute illness following freshwater contact if a description is given of a waterbody visibly affected by planktonic mass development