SYNTESIS AND CRYSTALLINE STRUCTURE OF THE EXO-3,6-DIMETHYL-3,6-EPOXI-1,2,3,6-TETRAHYDROPHTLALIMIDE AND ITS N-BROMODECYL ANALOG: TWO THERMALLY LABILE DIELS-ALDER ADDUCTS

Indexación: Web of Science; Scielo.The molecular structure of the exo-3,6-dimethyl-3,6-epoxi-1,2,3,6-tetrahydrophthalimide (1), determined by X-ray diffraction analysis, as well as, its complete spectroscopic characterization and the synthesis and complete spectroscopic characterization of its N-(10-bromodecyl) analog (2) are presented.http://ref.scielo.org/kh5xv

Challenges in imaging and predictive modeling of rhizosphere processes

Background Plant-soil interaction is central to human food production and ecosystem function. Thus, it is essential to not only understand, but also to develop predictive mathematical models which can be used to assess how climate and soil management practices will affect these interactions. Scope In this paper we review the current developments in structural and chemical imaging of rhizosphere processes within the context of multiscale mathematical image based modeling. We outline areas that need more research and areas which would benefit from more detailed understanding. Conclusions We conclude that the combination of structural and chemical imaging with modeling is an incredibly powerful tool which is fundamental for understanding how plant roots interact with soil. We emphasize the need for more researchers to be attracted to this area that is so fertile for future discoveries. Finally, model building must go hand in hand with experiments. In particular, there is a real need to integrate rhizosphere structural and chemical imaging with modeling for better understanding of the rhizosphere processes leading to models which explicitly account for pore scale processes

Measuring rhizosphere hydraulic properties: impact of root mucilage on soil hydraulic conductivity and water retention curve

Roots are hypothesized to alter rhizosphere hydraulic properties by release of mucilage. This mechanism is expected to have strong implications for root water uptake under drought conditions. Direct measurement of rhizosphere hydraulic properties is hindered by the dynamic nature of the components involved; root hydraulics change with ontology; mucilage production, composition and diffusion are not constant; soil water content changes. An experimental approach was developed which enables to simultaneously measure hydraulic conductivity and apparent water retention curve in a radial flow setup, mimicking the flow geometry around roots. The method consists of extracting water at constant suction via a suction cup, which is centrally placed in a soil filled cylinder and recording water outflow and soil matric potential. In the past, the setup was tested for homogeneous distribution of a model substance (calcium-polygalacturonic acid) frequently used to mimic the properties of root mucilage. Now the system has been applied to investigate the impact of plant root mucilage collected from white lupine. As the system allows a local placement of mucilage treated soil around the suction cup to simulate a ‘rhizosphere’ between bulk soil and suction cup, it can be set up with the limited quantity of natural plant root mucilage available from direct collection. Quartz sand has been treated with lupine root mucilage by mixing liquid mucilage with dry sand at a concentration of 2 mg mucilage per gram soil. Treated sand has been placed as a circular layer with 3.75 mm thickness around the suction cup, which has a radius of 1.25 mm. All around this layer, the device has been filled up with untreated sand. The radius of the whole device was 25 mm. To determine soil hydraulic conductivity we inversely fitted the outflow curves and soil matric potential by solving the Richards’ equation in radial coordinates. Water outflow curves show a significant impact of lupine mucilage on water flow rate – it slows water flow from bulk soil to suction cup. Currently modelling is in process to determine soil hydraulic conductivity and water retention curves. Decreasing hydraulic conductivities and increasing water retention due to lupine mucilage treatment are expected

Testing hypotheses on interlinks between silicon and organic matter cycling in rice ecosystems

Recent studies demonstrated that sufficient Si supply enhances the resistance of rice plants against biotic and abiotic stresses. The mechanisms by which Si supports the stress resistance are still under debate. One hypothesis assumes that phytoliths exert similar eco-physiological functions as organic structural compounds. The formation of amorphous Si oxide bodies (`phytoliths`) within the plant tissue, therefore, represents an energy-saving alternative to synthesis of organic structural compounds, such as cellulose and lignin. Hence, Si availability may interact with the recycling of organic matter because rates of plant litter decomposition are regulated by contents of structural organic compounds. We currently test the hypothesis using a large set of rice straw samples collected at 70 paddy fields in Vietnam and the Philippines. Due to the differing portions of weatherable silicate minerals in soil, Si availability varies largely between the fields; the Si concentrations in the straw samples, thus, range from 1.6 to 10.7%. The Si concentrations are significantly negatively related to carbon concentrations, which range from 31.1 to 42.5% (the R2 of the linear relationship is 0.83). In turn, no relationships between Si and nitrogen concentrations were found. These findings support the assumption that Si substitutes N-poor structural compounds in rice plants. Currently, we apply cupric oxide oxidation analysis to the straw samples in order to test for relationships between concentrations Si and lignin. The results will be included into the proposed presentation

Soil texture is a stronger driver of the maize rhizosphere microbiome and extracellular enzyme activities than soil depth or the presence of root hairs

Aims Different drivers are known to shape rhizosphere microbiome assembly. How soil texture (Texture) and presence or lack of root hairs (Root Hair) of plants affect the rhizosphere microbiome assembly and soil potential extracellular enzyme activities (EEA) at defined rooting depth (Depth) is still a knowledge gap. We investigated effects of these drivers on microbial assembly in rhizosphere and on potential EEA in root-affected soil of maize. Methods Samples were taken from three depths of root hair defective mutant rth3 and wild-type WT maize planted on loam and sand in soil columns after 22 days. Rhizosphere bacterial, archaeal, fungal and cercozoan communities were analysed by sequencing of 16S rRNA gene, ITS and 18S rRNA gene fragments. Soil potential EEA of ss-glucosidase, acid phosphatase and chitinase were estimated using fluorogenic substrates. Results The bacterial, archaeal and cercozoan alpha- and beta-diversities were significantly and strongly altered by Texture, followed by Depth and Root Hair. Texture and Depth had a small impact on fungal assembly, and only fungal beta-diversity was significantly affected. Significant impacts by Depth and Root Hair on beta-diversity and relative abundances at taxonomic levels of bacteria, archaea, fungi and cercozoa were dependent on Texture. Likewise, the patterns of potential EEA followed the trends of microbial communities, and the potential EEA correlated with the relative abundances of several taxa. Conclusions Texture was the strongest driver of rhizosphere microbiome and of soil potential EEA, followed by Depth and Root Hair, similarly to findings in maize root architecture and plant gene expression studies

Global Governance Behind Closed Doors : The IMF Boardroom, the Enhanced Structural Adjustment Facility, and the Intersection of Material Power and Norm Change in Global Politics

Up on the 12th floor of its 19th Street Headquarters, the IMF Board sits in active session for an average of 7 hours per week. Although key matters of policy are decided on in the venue, the rules governing Boardroom interactions remain opaque, resting on an uneasy combination of consensual decision-making and weighted voting. Through a detailed analysis of IMF Board discussions surrounding the Enhanced Structural Adjustment Facility (ESAF), this article sheds light on the mechanics of power in this often overlooked venue of global economic governance. By exploring the key issues of default liability and loan conditionality, I demonstrate that whilst the Boardroom is a more active site of contestation than has hitherto been recognized, material power is a prime determinant of both Executive Directors’ preferences and outcomes reached from discussions. And as the decisions reached form the backbone of the ‘instruction sheet’ used by Fund staff to guide their everyday operational decisions, these outcomes—and the processes through which they were reached—were factors of primary importance in stabilizing the operational norms at the heart of a controversial phase in the contemporary history of IMF concessional lending

Outcomes and Complication Rates of Cuff Downsizing in the Treatment of Worsening or Persistent Incontinence After Artificial Urinary Sphincter Implantation

Purpose This study investigated the functional outcomes and complication rates of cuff downsizing for the treatment of recurrent or persistent stress urinary incontinence (SUI) in men after the implantation of an artificial urinary sphincter (AUS). Methods Data from our institutional AUS database spanning the period from 2009 to 2020 were retrospectively analyzed. The number of pads per day was determined, a standardized quality of life (QoL) questionnaire and the International Consultation on Incontinence Questionnaire (ICIQ) were administered, and postoperative complications according to the Clavien-Dindo classification were analyzed. Results Out of 477 patients who received AUS implantation during the study period, 25 (5.2%) underwent cuff downsizing (median age, 77 years; interquartile range [IQR], 74–81 years; median follow-up, 4.4 years; IQR, 3–6.9 years). Before downsizing, SUI was very severe (ICIQ score 19–21) or severe (ICQ score 13–18) in 80% of patients, moderate (ICIQ score 6–12) in 12%, and slight (ICIQ score 1–5) in 8%. After downsizing, 52% showed an improvement of >5 out of 21 points. However, 28% still had very severe or severe SUI, 48% had moderate SUI, and 20% had slight SUI. One patient no longer had SUI. In 52% of patients, the use of pads per day was reduced by ≥50%. QoL improved by >2 out of 6 points in 56% of patients. Complications (infections/urethral erosions) requiring device explantation occurred in 36% of patients, with a median time to event of 14.5 months. Conclusions Although cuff downsizing carries a risk of AUS explantation, it can be a valuable treatment option for selected patients with persistent or recurrent SUI after AUS implantation. Over half of patients experienced improvements in symptoms, satisfaction, ICIQ scores, and pad use. It is important to inform patients about the potential risks and benefits of AUS to manage their expectations and assess individual risks