Coupling of diagenetic alterations and mechanical properties of Lower Permian siliciclastic sandstones: a pilot study

Initial detrital composition and authigenic alterations during diagenesis of three sandstone types are related to their mechanical properties. Sandstones were prepared for geotechnical standard tests [density, uniaxial compressive strength (UCS), Young’s modulus (E), strain at failure (ε)] and thin sections for petrographic analyses (point counting). UCS ranges from 3 to 62 MPa and positively correlates with density (1.75–2.35 g/cm3) and E (0.3–12.7 GPa). Optical porosity is controlling these mechanical parameters and was linked to diagenetic alterations. Diagenetic alterations affecting porosity reduction are the abundance of clay minerals, and the intensity of mechanical and chemical compaction. The latter is controlled by clay mineral coatings on contacts between detrital grains, and the occurrence of authigenic quartz and dolomite. Horizontal contact lengths of grains normalized to their respective particle diameter (effective contact ratio, ECR) and porosity are identified as a control on the mechanical properties UCS and E, reflected by the rock strength index SR. The results of this pilot study suggest that SR is able to predict UCS and E based on petrographic information obtained from the studied samples. These results enhance the understanding of the coupling between mineralogy and geomechanics and highlight the impact of diagenesis on geomechanical behavior

Coronavirus disease 2019 (COVID-19) research agenda for healthcare epidemiology

This SHEA white paper identifies knowledge gaps and challenges in healthcare epidemiology research related to coronavirus disease 2019 (COVID-19) with a focus on core principles of healthcare epidemiology. These gaps, revealed during the worst phases of the COVID-19 pandemic, are described in 10 sections: epidemiology, outbreak investigation, surveillance, isolation precaution practices, personal protective equipment (PPE), environmental contamination and disinfection, drug and supply shortages, antimicrobial stewardship, healthcare personnel (HCP) occupational safety, and return to work policies. Each section highlights three critical healthcare epidemiology research questions with detailed description provided in supplementary materials. This research agenda calls for translational studies from laboratory-based basic science research to well-designed, large-scale studies and health outcomes research. Research gaps and challenges related to nursing homes and social disparities are included. Collaborations across various disciplines, expertise and across diverse geographic locations will be critical

Aquaponics in the Built Environment

Aquaponics’ potential to transform urban food production has been documented in a rapid increase of academic research and public interest in the field. To translate this publicity into real-world impact, the creation of commercial farms and their relationship to the urban environment have to be further examined. This research has to bridge the gap between existing literature on growing system performance and urban metabolic flows by considering the built form of aquaponic farms. To assess the potential for urban integration of aquaponics, existing case studies are classified by the typology of their building enclosure, with the two main categories being greenhouses and indoor environments. This classification allows for some assumptions about the farms’ performance in their context, but a more in-depth life cycle assessment (LCA) is necessary to evaluate different configurations. The LCA approach is presented as a way to inventory design criteria and respective strategies which can influence the environmental impact of aquaponic systems in the context of urban built environments

Chapitre 14: Phytopathogènes et stratégies de contrôle en aquaponie

peer reviewedAmong the diversity of plant diseases occurring in aquaponics, soil-borne pathogens, such as Fusarium spp., Phytophthora spp. and Pythium spp., are the most problematic due to their preference for humid/aquatic environment conditions. Phytophthora spp. and Pythium spp. which belong to the Oomycetes pseudo-fungi require special attention because of their mobile form of dispersion, the so-called zoospores that can move freely and actively in liquid water. In coupled aquaponics, curative methods are still limited because of the possible toxicity of pesticides and chemical agents for fish and beneficial bacteria (e.g. nitrifying bacteria of the biofilter). Furthermore, the development of biocontrol agents for aquaponic use is still at its beginning. Consequently, ways to control the initial infection and the progression of a disease are mainly based on preventive actions and water physical treatments. However, suppressive action (suppression) could happen in aquaponic environment considering recent papers and the suppressive activity already highlighted in hydroponics. In addition, aquaponic water contains organic matter that could promote establishment and growth of heterotrophic bacteria in the system or even improve plant growth and viability directly. With regards to organic hydroponics (i.e. use of organic fertilisation and organic plant media), these bacteria could act as antagonist agents or as plant defence elicitors to protect plants from diseases. In the future, research on the disease suppressive ability of the aquaponic biotope must be increased, as well as isolation, characterisation and formulation of microbial plant pathogen antagonists. Finally, a good knowledge in the rapid identification of pathogens, combined with control methods and diseases monitoring, as recommended in integrated plant pest management, is the key to an efficient control of plant diseases in aquaponics.Cos

Filter helix implementation into an S-band TWT design

The performance of an S-band traveling wave tube (TWT) is enhanced by introducing a filter consisting of periodic transmission line discontinuities into its delay line. The filter is designed to suppress the second harmonic which is particularly strong in this tube especially at low frequencies. The main goal, i.e. to improve the electron velocity spectrum at the lower operating band and, thus, to extend the bandwidth of the tube, is demonstrated

Coupling of diagenetic alterations and mechanical properties of Lower Permian siliciclastic sandstones: a pilot study

Initial detrital composition and authigenic alterations during diagenesis of three sandstone types are related to their mechanical properties. Sandstones were prepared for geotechnical standard tests [density, uniaxial compressive strength (UCS), Young’s modulus (E), strain at failure (ε)] and thin sections for petrographic analyses (point counting). UCS ranges from 3 to 62 MPa and positively correlates with density (1.75–2.35 g/cm3) and E (0.3–12.7 GPa). Optical porosity is controlling these mechanical parameters and was linked to diagenetic alterations. Diagenetic alterations affecting porosity reduction are the abundance of clay minerals, and the intensity of mechanical and chemical compaction. The latter is controlled by clay mineral coatings on contacts between detrital grains, and the occurrence of authigenic quartz and dolomite. Horizontal contact lengths of grains normalized to their respective particle diameter (effective contact ratio, ECR) and porosity are identified as a control on the mechanical properties UCS and E, reflected by the rock strength index SR. The results of this pilot study suggest that SR is able to predict UCS and E based on petrographic information obtained from the studied samples. These results enhance the understanding of the coupling between mineralogy and geomechanics and highlight the impact of diagenesis on geomechanical behavior.Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347Projekt DEA

Dialkylphosphinoimidazoles as New Ligands for Palladium-Catalyzed Coupling Reactions of Aryl Chlorides

International audienc

BASELLA ALBA (BASELLACEAE) AND MALE REPRODUCTIVE FUNCTION

Hibiscus macranthus and Basella alba leaves are mixed in a remedy given, in western Cameroon, to the new king for some weeks during initiation period to sustain his sexual performance. This plant extracts enhanced blood testosterone level in male rats. They were further studied for androgenic activity since they could be used to alleviate male infertility or to treat androgen deficiency in ageing male. Using rat testis slices, methanol extract of both plants significantly induced testosterone synthesis. In primary Leydig cell cultures of bull and rat, extracts from B. alba significantly enhanced testosterone levels in a dose dependant manner. H. macranthus showed no androgenic activity. Phytochemical screening and HPLC study of B. alba extracts revealed presence of terpenoids, limonoides and coumarins. This extract also modulated aromatase gene activity in Leydig cell cultures. In vivo, methanol extract (1 mg/kg) given to adult male rats significantly increased serum testosterone level after 30 days (

Effect of methanol extract of Basella alba L. (Basellaceae) on the fecundity and testosterone level in male rats exposed to flutamide in utero

International audienceWe evaluated the effect of the methanol extract of Basella alba (MEBa) on testosterone level and fecundity/fertility in male rats exposed in utero to flutamide an androgen receptor antagonist. For this purpose, 1.5- and 2.5 -month-old male rats exposed in utero to flutamide were treated with the MEBa (1 mg kg-1) for 2 and 1 month respectively. Five days before the end of treatment, rats were housed with females to assess their fecundity/fertility. Thereafter, rats were sacrificed and blood collected for the quantification of testosterone. Flutamide-exposed male rats showed a decrease in their ano-genital distance (AGD, P < 0.05) and were infertile. In normal (methylcellulose-exposed) animals, MEBa provoked an increase in testosterone level in 1.5- (P < 0.008) and 2.5 -month-old rats (P < 0.01) concomitantly with the improvement in their fecundity by 25%. In flutamide-exposed male rats, MEBa increased testosterone level in 1.5 -month-old rats (P < 0.001) without any effect on their fecundity; while in 2.5- month-old rats, MEBa did not affect the testosterone level but improved fecundity (by 25%) and fertility (P < 0.001). This study demonstrated the positive effect of MEBa to enhance fecundity/fertility in normal male rats and in rats exposed to the antiandrogen flutamide during their foetal life