1,723,121 research outputs found
Assessment of ammonia and ammonium trends and relationship to critical levels in the UK National Ammonia Monitoring Network (NAMN)
No full textThe UK National Ammonia Monitoring Network (NAMN, Sutton et al. 2001a) was established in 1996 to quantify the spatial distribution and long-term trends in concentrations of atmospheric ammonia (NH3) and also aerosol ammonium (NH4 +) (since 1999). There are currently 94 sites. At 59 of these sites, the CEH DELTA methodology (Sutton et al. 2001b) is used to provide the spatial and temporal patterns of NH3 and aerosol NH4 + across the UK, while passive diffusion samplers (Tang et al. 2001) are used to assess regional and local scale variability in air NH3 concentrations in source regions. Monitoring is on a monthly timescale, which is optimal to provide information on seasonality and for estimating annual mean in air concentrations.
Emissions of NH3 in the UK have fallen by 12% between 1990 and 2004 (http://www.naei.org.uk). The long-term dataset from the UK NAMN, which comprises 9 years of gaseous NH3 data (since September 1996) and 7 years of aerosol NH4 + data (since 1999) may therefore be analysed to assess trends in air concentrations. The data can also be used to compare with critical levels of NH3 concentrations set in the UK to protect vegetation and ecosystem
Switching on the activity of 1,5-diaryl-pyrrole derivatives against drug-resistant ESKAPE bacteria
No full textAntibiotic resistance represents a significant threat worldwide. There is an urgent need to discover structurally innovative antibacterial agents for which no pre-existing resistance is known.
With the aim to speed up the drug discovery process and to reduce the limitations of target-based high-through put screenings (HTS) we described the synthesis and biological evaluation of a novel series of 1,5-diphenylpyrroles active against a wide panel of ESKAPE bacteria. In particular, a subsequent structure-activity relationship (SAR) study revealed that the modification of the functional groups can switch the selectivity and the antimicrobial activity from mycobacteria to Gram positive and Gram negative bacteria [1,2].
The new compounds show high activity against both wild type and drug-resistant Gram positive and Gram negative bacteria at concentrations similar than levofloxacin.
Microbiology studies revealed that the plausible target of this class of compounds is the bacterial DNA gyrase, with the pyrrole derivatives displaying similar inhibitory activity to levofloxacin against the wild type enzyme and retaining activity against the fluoroquinolone-resistant enzyme.
References:
[1] Bhakta, S.; Manetti, F.; Castagnolo, D. et al (2016) Design and Synthesis of 1-((1,5-Bis(4-chlorophenyl)-2-methyl-1H-pyrrol-3-yl)methyl)-4-methylpiperazine (BM212) and N-Adamantan-2-yl-N′-((E)-3,7-dimethylocta-2,6-dienyl)ethane-1,2-diamine (SQ109) Pyrrole Hybrid Derivatives: Discovery of Potent Antitubercular Agents Effective against Multidrug-Resistant Mycobacteria. J. Med. Chem.59:2780-2793.
[2] Masci, D.; Hind, C.; K. Islam, M.; Toscani, A.; Clifford, M.; Coluccia, A.; Conforti, I.; Touitou, M.; Wei, X.; Memdouh, S.; La Regina, G.; Silvestri, R; Sutton, M.; Castagnolo, D. (2019) Switching on the activity of 1,5-diaryl-pyrrole derivatives against drug-resistant ESKAPE bacteria: structure-activity relationships and mode of action studies. Eur. J. Med. Chem. 178:500-514
Assessment of critical levels of atmospheric ammonia for lichen diversity in cork-oak woodland, Portugal
No full textThe effect of atmospheric ammonia on ecosystems has been the subject of ongoing research. Its adverse effects as an air pollutant are well characterised, and may be even more widespread than previously thought (see Aber et al. 2003; Erisman et al. 2003; Krupa 2003; Purvis et al. 2003). The most important sources of NH3 in Europe are agricultural activities, mainly crop fertilization and cattle management (Galloway et al. 2003; EPER 2004). Livestock housing facilities are recognised to be large point sources of NH3 emissions. Close to such facilities, atmospheric NH3 concentrations are very high, decreasing rapidly with distance over a few hundreds of meters to a few kilometres (Sutton et al. 1998). Measurement of atmospheric NH3 in the vicinity of livestock housing include those by Pitcairn et al. (1998, 2003), with reported values in Scotland of 24 –59 μg m−3 close to source, which declined to background values of 1.6 –5 μg m−3 at 1 km. In order to assess the range of effects of NH3 in natural ecosystems, that can be used for effective NH3 mitigation policies (Dragosits et al. 2006), one can rely on two distinct approaches: (i) direct measurements of atmospheric NH3 concentrations, which provide an estimate of dry NH3-N deposition, but require intensive and costly operations; (ii) monitoring of effects on the biotic component. The latter approach should be carried out using groups of biota that are more sensitive to the pollutant of interest. Lichens have been reported as the most sensitive group to NH3 emissions (e.g. Wolseley et al. 2006a; van Herk 1999). Lichens are symbiotic organisms widely used as biomonitors of environmental changes (e.g. Nimis et al. 1991; Vokou et al. 1999; Geebelen and Hoffmann 2001; Giordani et al. 2002; Pirintsos and Loppi 2003; Geiser and Neitlich 2007).
Monitoring atmospheric pollutants using lichens may be undertaken in three ways: (1) measuring variations in lichens diversity and/or abundance, (2) using variations in physiological parameters, and/or using lichens as accumulators of pollutants (Branquinho 2001), and (3) considering functional groups related to nutrients tolerance, such as the division between nitrophytic/oligotrophic (or nitrophytic/ acidophitic) groups (see van Dobben and ter Braak 1999; Ruisi et al. 2005; Wolseley et al. 2006b)
Recommended from our members
Sutton: Archaeological Investigations at Cantil, Fremont Valley, Western Mojave Desert, California; and Sutton, ed.: Archaeological Studies in the Goose Lake Area, Southern San Joaquin Valley, California
Get PDFArchaeological Investigations at Cantil, Fremont Valley, Western Mojave Desert, California. Mark Q. Sutton, with contributions by Paul D. Bouey, John D. Goodman II, Margaret M. Lyneis, Karen K. Swope, and Robert M. Yohe II. Museum of Anthropology, California State University, Bakersfield, Occasional Papers in Anthropology No. 1, 1991, x + 225 pp., 74 figs., 67 tables, 6.00 (paper)
Spatial planning as a complementary tool to abate the effects of atmospheric ammonia deposition at the landscape scale
No full textSimple and rapid sample preparation system for the molecular detection of antibiotic resistant bacteria in human urine
Get PDFAntibiotic resistance in urinary tract infections (UTIs) can cause significant complications without quick detection and appropriate treatment. . We describe a new approach to capture, concentrate and prepare amplification-ready DNA from antibiotic resistant bacteria in human urine samples. Klebsiella pneumoniae NCTC13443 (blaCTX-M-15 positive) spiked into filtered human urine was used as a model system. Bacteria were captured using anion exchange diaethylaminoethyl (DEAE) magnetic microparticles and concentrated 200-fold within ~3.5 minutes using a custom, valve-less microfluidic chip. Eight samples were processed in parallel, and DNA, was released using heat lysis from an integrated resistive heater. The crude cell lysate was used for real time Recombinase Polymerase Amplification (RPA) of the blaCTX-M-15 gene. The end to end processing time was approximately 15 minutes with a limit of detection of 1000 bacteria in 1 mL urin
Coordinating European nitrogen policies between international conventions and intergovernmental organizations
No full textRecommended from our members
Adaptation of Cue-Specific Learning Rates in Network Models of Human Category Learning
Get PDFRecent engineering considerations have prompted an improvement to the least mean squares (LMS) learning rule for training one-layer adaptive networks; incorporating a dynamically modifiable learning rate for each associative weight accellerates overall learning and provides a mechanism for adjusting the salience of individual cues (Sutton, 1992a,b). Prior research has established that the standard L M S rule can characterize aspects of animal learning (Rescorla & Wagner, 1972) and human category learning (Gluck & Bower, 1988a,b). W e illustrate here how this enhanced L M S rule is analogous to adding a cue-salience or attentional component to the psychological model, giving the network model a means for discriminating between relevant and irrelevant cues. W e then demonstrate the effectiveness of this enhanced L M S rule for modeling human performance in two non-stationary learning tasks for which the standard L M S network model fails to adequately account for the data (Hurwitz, 1990; Gluck, Glauthier, & Sutton, in preparation)
Models of scientific explanation
Get PDFEver since Hempel and Oppenheim's development of the Deductive Nomological model
of scientific explanation in 1948, a great deal of philosophical energy has been dedicated
to constructing a viable model of explanation that concurs both with our intuitions and
with the general project of science. Here I critically examine the developments in this
field of study over the last half century, and conclude that Humphreys' aleatory model is
superior to its competitors. There are, however, some problems with Humphreys'
account of the relative quality of an explanation, so in the end I develop and defend a
modified version of the aleatory account
- …
