Understanding the Impact of Fluid Viscosity on the Growth and Conjugation of Antimicrobial Resistant Donors and Recipients Pairs

To combat the spread of antimicrobial resistance (AMR), it is vital to link the behavior of donor and recipient bacteria in dynamic environments to horizontal gene transfer (HGT) potential- specifically, conjugation the primary means of spread of AMR genes. However, HGT is poorly understood under dynamic conditions, such as those in the gut of humans and animals. Most experiments are done under static conditions at viscosities similar to water, but these methods do not accurately represent the higher gut viscosities or movement. Hence, a next step to increase understanding of conjugation is with experiments using generic donor and recipient pairs at different viscosities. Accordingly, it is necessary to establish the relationship between viscosity and bacterial growth in these experiments, for which our hypothesis is that the rate of bacterial growth in fluids with higher viscosities will be lower due to water displacement. To test this hypothesis, experiments were designed to measure the number of donors, recipients and transconjugant bacteria using optical density. Varying concentrations of the thickeners agar and xanthan gum will be used to achieve different viscosity levels in the media. Media of thicknesses closer to that of bodily fluids, which are more alike to pancake syrup or batter, will be evaluated. Concentrations will be tracked at half hour intervals as a means to obtain data and to formulate a growth curve model. Some preliminary results indicate that our hypothesis has a good probability of being correct. Linear growth curve models were applied to the data for comparison purposes

Mechanisms of degradation of concrete by external sulfate ions under laboratory and field conditions

The durability of concrete is a major challenge for the construction, which devotes one third to one half of its annual investment to building maintenance. The lack of field data regarding concrete durability, especially in the case of exposure to sulfate ions ("sulfate attack") makes it difficult to determine the appropriate test methods and performance criteria. Additionally, the increased use of blended concretes (cement with mineral admixtures) suffers from a lack of experience regarding their long-term performance. Most results for sulfate resistance are derived from accelerated laboratory tests where performance criteria are based only on macroscopic properties, especially expansion. To fill this gap and better understand the mechanisms of sulfate attack under real conditions, a parallel study of laboratory micro-concrete and field concrete samples under sulfate exposure was undertaken, focussing on microstructural changes in addition to the typical macroscopic characterisation. Four exposure regimes were designed in the laboratory: full immersion (traditional test in "ponding"), pH-control, semi-immersion and wet/dry cycles. Pure Portland blends and slag blends with high level of slag replacement (70 wt.-%) were investigated. The exposure regime has been found to play a main role in the damage process. In ponding conditions, the damage process takes place three stages characterised by a first period of induction, followed by surface damage that finally extends to the bulk of the material. Paradoxically, the w/c-ratio does not seem to have much impact on the ionic transport phenomena but might be more decisive in the microstructure mechanical strength against local stresses. The slag blends, considered as sulfate resistant in ponding exposure, revealed bad performance under wet/dry cycles. This behaviour was attributed to poor proper physical resistance of the slag hydrates to the applied drying. Field observations tend to confirm the laboratory results and validate the test settings. It has been underlined that a direct relationship between the damage (e.g.; cracking/expansion) and the phase assemblage was not evident. However, the study highlights that sulfate combination with the hydrates of cement (e.g.; C-S-H) and to those of slag was found to play a role in the initiation of expansion, which would be initiated either by a swelling of the hydrates or by the precipitation of fine ettringite when the saturation level in sulfate of the hydrates has been reached

«Industrie und Fachhochschule brauchen sich gegenseitig»

Aude Chabrelie und Urs-Thomas Gerber unterrichten an der BFH im Bereich nachhaltiges Bauen mit den Schwerpunkten Nachhaltigkeitsanalysen und zirkuläres Bauen. Mit ihrer grossen Erfahrung aus der Privatwirtschaft wollen sie den Studierenden Mut machen, Einfluss zu nehmen

Notes sur quelques croyances des Sara.

Chabrelie Louis. Notes sur quelques croyances des Sara.. In: Journal de la Société des Africanistes, 1933, tome 3, fascicule 2. pp. 315-318

Notes sur la langue des Sara, avec un vocabulaire comparatif des différents dialectes

Chabrelie Louis. Notes sur la langue des Sara, avec un vocabulaire comparatif des différents dialectes. In: Journal de la Société des Africanistes, 1935, tome 5, fascicule 2. pp. 125-151

World Gas Prospects: Which Role for the Middle East? Perspectives mondiales du gaz naturel : quel rôle pourrait jouer le Moyen-Orient ?

Since the early 1970s, the policies of energy diversification that have been implemented in the industrialized countries and in many developing countries have enabled natural gas to regularly increase its role in the world energy balance. Thus, during the past twenty years, natural gas recorded the highest growth rate among fossil fuels, and its share in the energy market has gradually risen from 18. 9% in 1975 to 23% in 1997. Today, thanks to favorable economic and environmental factors, natural gas has become the fuel of choice on many markets. Indeed, gas is blessed with a certain number of favorable assets (abundant reserves, flexibility, high-performance uses) which give it a major role in all energy demand forecast scenarios. The most spectacular development will indisputably take place in the power generation sector. Endowed with a considerable gas potential, the Middle East will represent an essential source of supply for many industrialized countries and several gas export projects, either by LNG tanker or by pipelines are currently being contemplated. During the past decade, the contribution of natural gas to the energy mix also grew substantially in most Middle Eastern countries. The increase in gas demand should continue at a sustained rate, mainly driven by the power generation sector, petrochemicals and energy consumption by the hydrocarbons industry. These promising prospects for gas demand in most of the markets in the region might lead to the development of an intra-regional network. However, although opportunities exist, the region will have to meet many challenges in order to contribute more largely to the world gas balance in the years to come. <br> de diversification énergétique mises en Suvre dans les pays industrialisés et dans de nombreux pays en voie de développement depuis le début des années 1970 ont permis au gaz naturel d'accroître régulièrement sa présence dans le bilan énergétique mondial. Ainsi, au cours des vingt dernières années, le gaz naturel a enregistré le taux de croissance le plus élevé parmi les énergies fossiles, et sa part de marché est progressivement passée de 18,9 % en 1975 à 23 % en 1997. Aujourd'hui, des facteurs d'ordres économiques et environnementaux font du gaz naturel l'énergie de choix sur de nombreux marchés. Le gaz jouit en effet d'un certain nombre d'atouts (réserves importantes, flexibilité, utilisations performantes) qui lui confèrent une place majeure dans tous les scénarios de prévision de demande énergétique. Le développement le plus spectaculaire se fera sans conteste dans le secteur électrique. Doté de réserves gazières considérables, le Moyen-Orient représentera une source d'approvisionnement essentielle pour bon nombre de pays industrialisés et plusieurs projets d'exportation de gaz par méthaniers ou par gazoducs sont déjà à l'étude. Par ailleurs, au cours des dix dernières années, la contribution du gaz naturel dans le bilan énergétique a augmenté de façon significative dans la plupart des pays du Moyen-Orient. La croissance de l'utilisation du gaz devrait se poursuivre à un rythme soutenu, en particulier sous l'influence du secteur électrique, de la pétrochimie et de l'autoconsommation de l'industrie pétrolière. Ces perspectives prometteuses de demande de gaz sur la plupart des marchés de la région pourraient conduire au développement d'un réseau de transport intrarégional. Toutefois, bien que des opportunités existent, elles ne doivent pas masquer les nombreux défis que cette région devra relever pour contribuer plus largement au bilan gazier mondial dans les années à venir

Multilevel Correlations in the Biological Phosphorus Removal Process: from Bacterial Enrichment to Conductivity-Based Metabolic Batch Tests and Polyphosphatase Assays

Enhanced biological phosphorus removal (EBPR) from wastewater relies on the preferential selection of active polyphosphate-accumulating organisms (PAO) in the underlying bacterial community continuum. Efficient management of the bacterial resource requires understanding of population dynamics as well as availability of bioanalytical methods for rapid and regular assessment of relative abundances of active PAOs and their glycogen-accumulating competitors (GAO). A systems approach was adopted here toward the investigation of multilevel correlations from the EBPR bioprocess to the bacterial community, metabolic, and enzymatic levels. Two anaerobic-aerobic sequencing-batch reactors were operated to enrich activated sludge in PAOs and GAOs affiliating with "Candidati Accumulibacter and Competibacter phosphates", respectively. Bacterial selection was optimized by dynamic control of the organic loading rate and the anaerobic contact time. The distinct core bacteriomes mainly comprised populations related to the classes Betaproteobacteria, Cytophagia, and Chloroflexi in the PAO enrichment and of Gammaproteobacteria, Alphaproteobacteria, Acidobacteria, and Sphingobacteria in the GAO enrichment. An anaerobic metabolic batch test based on electrical conductivity evolution and a polyphosphatase enzymatic assay were developed for rapid and low-cost assessment of the active PAO fraction and dephosphatation potential of activated sludge. Linear correlations were obtained between the PAO fraction, biomass specific rate of conductivity increase under anaerobic conditions, and polyphosphate-hydrolyzing activity of PAO/GAO mixtures. The correlations between PAO/GAO ratios, metabolic activities, and conductivity profiles were confirmed by simulations with a mathematical model developed in the aqueous geochemistry software PHREEQC. (C) 2014 Wiley Periodicals, Inc