Chemische und bakteriologische Untersuchungen des Trinkwassers der Stadt Bern

Ohne Zusammenfassung     

Structure–Activity Relationships of 2‐Sufonylpyrimidines as Quorum‐Sensing Inhibitors to Tackle Biofilm Formation and eDNA Release of Pseudomonas aeruginosa

Drug‐resistant Pseudomonas aeruginosa (PA) strains are on the rise, making treatment with current antibiotics ineffective. Hence, circumventing resistance or restoring the activity of antibiotics by novel approaches is of high demand. Targeting the Pseudomonas quinolone signal quorum sensing (PQS‐QS) system is an intriguing strategy to abolish PA pathogenicity without affecting the viability of the pathogen. Herein we report the structure–activity relationships of 2‐sulfonylpyrimidines, which were previously identified as dual‐target inhibitors of the PQS receptor PqsR and the PQS synthase PqsD. The SAR elucidation was guided by a combined approach using ligand efficiency and ligand lipophilicity efficiency to select the most promising compounds. In addition, the most effective inhibitors were rationally modified by the guidance of QSAR using Hansch analyses. Finally, these inhibitors showed the capacity to decrease biofilm mass and extracellular DNA, which are important determinants for antibiotic resistance.     

Calculated Contribution of Surface Microlayer PCB to Contamination of Lake Michigan Lake Trout

The possible significance of PCB concentration in the surface microlayer of Lake Michigan to contamination of lake trout was examined using a modification of a previously developed food chain model. Vertically migrating zooplankton were assumed to spend a fraction of each day exposed to a surface microlayer with dissolved and phytoplankton PCB concentrations at values that resulted in an average exposure concentration 2.1 times greater than subsurface levels. Considering a worst case scenario, the model indicated that approximately 12% (3 μg/g) of the PCB concentration in adult lake trout could be contributed from the microlayer.     

New type of Rayleigh-wave transducer on piezoelectric ceramics

An interdigital transducer on a piezoelectric ceramic with the polarisation directed from one comb to the other is described. The efficiency is determined by complex-admittance measurements.     

A case study of wind energy conversion systems in an electric utility system

The potential of wind energy conversion systems (WECS) in a regional electric utility system was investigated. The Kansas Gas and Electric Company (KG&E) with 1800 MW generating capacity served as the case study subject.The general methodologies utilized to conduct a case study of this nature are outlined and then applied to investigate the impacts of WECS on the specific electric utility system selected for this study. Five years of concurrent wind/load data were used to simulate 15 years of KG&E system operation without and with WECS. The KG&E system simulation computer programs were used to model hour-by-hour operation and to generate fuel requirements, production costs, and other reports. The “loss-of-load probability” (LOLP) index was also calculated for the system without and with WECS, from whcih the effective capacity of WECS was determined. Economic analysis was performed to assess the value of WECS in the KG&E system, and breakeven WECS costs were calculated by considering WECS as “fuel saver”, plus extra tax credit and capacity credit.     

Chromium-doped forsterite: dispersion measurement with white-light interferometry

Using a Michelson white-light interferometer, we measure the group-delay dispersion and third-order dispersion coefficients, d2(phi)/d(omega)2 and d3(phi)/d(omega)3, of chromium-doped forsterite (Cr:Mg2SiO4) over wavelengths of 1050-1600 nm for light polarized along both the c and b crystal axes. In this interval, the second-order dispersion for the c axis ranges from 35 fs2/mm to -14 fs2/mm, and the third-order dispersion ranges from 36 fs3/mm to 142 fs3/mm. For the b axis the second-order dispersion ranges from 35 fs2/mm to -15 fs2/mm and the third-order from 73 fs3/mm to 185 fs3/mm. Our data are relevant for the development of optimized dispersion compensation tools for Cr:Mg2SiO4 femtosecond lasers. These measurements help to clarify previously published results and show some significant discrepancies that existed, especially in the third-order dispersion. Our results should furthermore be useful to build up an analytic expression for the index of refraction of chromium forsterite.     

Data reduction using the least square method

In many cases an unknown function T(t) is approximated by a number of observations T_i(t_i) and the slope ∂T/∂t is needed. The slope is often calculated by fitting a polynomial through a group of the T_i(t_i) points using the least square method. In the present paper the error introduced into the slope is determined for some cases which are representative for experiments using the transient heat-transfer technique. The results can either be used when new experiments are planned or when the best combination of parameters (number of points approximated by the polynomial, degree of the polynomial) has to be determined for the reduction of existing data.

It was also found that, within the framework of assumptions made, an even degree polynomial gives exactly the same slope as the odd one with the next lower degree. Therefore, only odd degree polynomials should be used.