38 research outputs found
Bedrock geology of the Rangeley Lakes-Dead River basin region, western Maine
Guidebook for field trips in the Rangeley Lakes - Dead River Basin region, western Maine: 62nd annual meeting October 2, 3, and 4, 1970: title page, table of contents, foreword, essa
Maintaining education and professional development for anaesthesia trainees during the COVID-19 pandemic:the Self-isolAting Virtual Education (SAVEd) project
Application of mineralogical, petrological and geochemical tools for evaluating the palaeohdrogeological evolution of the PADAMOT study sites
The role of Work Package (WP) 2 of the PADAMOT project â âPalaeohydrogeological Data
Measurementsâ - has been to study late-stage fracture mineral and water samples from
groundwater systems in Spain, Sweden, United Kingdom and the Czech Republic, with the aim
of understanding the recent palaeohydrogeological evolution of these groundwater systems. In
particular, the project sought to develop and evaluate methods for obtaining information about
past groundwater evolution during the Quaternary (about the last 2 million years) by examining
how the late-stage mineralization might record mineralogical, petrographical and geochemical
evidence of how the groundwater system may have responded to past geological and
climatological changes.
Fracture-flow groundwater systems at six European sites were studied:
⢠Melechov Hill, in the Bohemian Massif of the Czech Republic: a shallow (0-100 m)
dilute groundwater flow system within the near-surface weathering zone in fractured
granitic rocks;
⢠Cloud Hill, in the English Midlands: a (~100 m) shallow dilute groundwater flow system
in fractured and dolomitized Carboniferous limestone;
⢠Los Ratones, in southwest Spain: an intermediate depth (0-500 m) dilute groundwater
flow system in fractured granitic rocks;
⢠Laxemar, in southeast Sweden: a deep (0-1000 m) groundwater flow system in fractured
granitic rocks. This is a complex groundwater system with potential recharge and
flushing by glacial, marine, lacustrine and freshwater during the Quaternary;
⢠Sellafield, northwest England: a deep (0-2000 m) groundwater flow system in fractured
Ordovician low-grade metamorphosed volcaniclastic rocks and discontinuous
Carboniferous Limestone, overlain by a Permo-Triassic sedimentary sequence with
fracture and matrix porosity. This is a complex coastal groundwater system with deep
hypersaline sedimentary basinal brines, and deep saline groundwaters in crystalline
basement rocks, overlain by a shallow freshwater aquifer system. The site was glaciated
several times during the Quaternary and may have been affected by recharge from glacial
meltwater;
⢠Dounreay, northeast Scotland: a deep (0-1400 m) groundwater flow system in fractured
Precambrian crystalline basement overlain by fractured Devonian sedimentary rocks.
This is within the coastal discharge area of a complex groundwater system, comprising
deep saline groundwater hosted in crystalline basement, overlain by a fracture-controlled
freshwater sedimentary aquifer system. Like Sellafield, this area experienced glaciation
and may potentially record the impact of glacial meltwater recharge.
In addition, a study has been made of two Quaternary sedimentary sequences in Andalusia in
southeastern Spain to provide a basis of estimating the palaeoclimatic history of the region that
could be used in any reconstruction of the palaeoclimatic history at the Los Ratones site:
⢠The Cúllar-Baza lacustrine sequence records information about precipitation and
palaeotemperature regimes, derived largely from the analysis of the stable isotope (δ18O
and δ13C) signatures from biogenic calcite (ostracod shells).
⢠The Padul Peat Bog sequence provided information on past vegetation cover and
palaeogroundwater inputs based on the study of fossil pollen and biomarkers as proxies
for past climate change.
Following on from the earlier EC 4th Framework EQUIP project, the focus of the PADAMOT
studies has been on calcite mineralization. Calcite has been identified as a late stage mineral, closely associated with hydraulically-conductive fractures in the present-day groundwater
systems at the ĂspĂś-Laxemar, Sellafield, Dounreay and Cloud Hill sites. At Los Ratones and
Melechov sites late-stage mineralization is either absent or extremely scarce, and both the
quantity and fine crystal size of any late-stage fracture mineralization relevant to Quaternary
palaeohydrogeological investigations is difficult to work with. The results from the material
investigated during the PADAMOT studies indicate that the fracture fillings at these sites are
related to hydrothermal activity, and so do not have direct relevance as Quaternary indicators.
Neoformed calcite has not been found at these two sites at the present depth of the investigations.
Furthermore, the HCO3
- concentration in all the Los Ratones groundwaters is mainly controlled
by complex carbonate dissolution. The carbonate mineral saturation indices do not indicate
precipitation conditions, and this is consistent with the fact that neoformed calcite, ankerite or
dolomite have not been observed petrographically
Erroneous neuraxial administration of neuromuscular blocking drugs:Case reports and 'the absence of evidence'
A Synthetic High-Spin Oxoiron(IV) Complex: Generation, Spectroscopic Characterization, and Reactivity
High versus low: The high-yield generation of a synthetic high-spin oxoiron(IV) complex, [FeIV(O)(TMG3tren)]2+ (see picture, TMG3tren = 1,1,1-tris{2-[N2-(1,1,3,3-tetramethylguanidino)]ethyl}amine), has been achieved by using the very bulky tetradentate TMG3tren ligand, in order to both sterically protect the oxoiron(IV) moiety and enforce a trigonal bipyramidal geometry at the iron center, for which an S=2 ground state is favored
A more reactive trigonal-bipyramidal high-spin oxoiron(IV) complex with a cis-labile site
The trigonal-bipyramidal high-spin (S = 2) oxoiron(IV) complex [FeIV(O)(TMG2dien)(CH3CN)]2+ (7) was synthesized and spectroscopically characterized. Substitution of the CH3CN ligand by anions, demonstrated here for X = N3â and Clâ, yielded additional S = 2 oxoiron(IV) complexes of general formulation [FeIV(O)(TMG2dien)(X)]+ (7-X). The reduced steric bulk of 7 relative to the published S = 2 complex [FeIV(O)(TMG3tren)]2+ (2) was reflected by enhanced rates of intermolecular substrate oxidation
Oxytocin can regulate myometrial smooth muscle excitability by inhibiting the Na+ -activated K+ channel, Slo2.1.
At the end of pregnancy, the uterus transitions from a quiescent state to a highly contractile state. This transition requires that the uterine (myometrial) smooth muscle cells increase their excitability, although how this occurs is not fully understood. We identified SLO2.1, a potassium channel previously unknown in uterine smooth muscle, as a potential significant contributor to the electrical excitability of myometrial smooth muscle cells. We found that activity of the SLO2.1 channel is negatively regulated by oxytocin via GÎąq-protein-coupled receptor activation of protein kinase C. This results in depolarization of the uterine smooth muscle cells and calcium entry, which may contribute to uterine contraction. These findings provide novel insights into a previously unknown mechanism by which oxytocin may act to modulate myometrial smooth muscle cell excitability. Our findings also reveal a new potential pharmacological target for modulating uterine excitability.info:eu-repo/semantics/publishe
Supplementary Material for: Na<sup>+</sup>-Leak Channel, Non-Selective (NALCN) Regulates Myometrial Excitability and Facilitates Successful Parturition
<b><i>Background/Aims:</i></b> Uterine contractility is controlled by electrical signals generated by myometrial smooth muscle cells. Because aberrant electrical signaling may cause inefficient uterine contractions and poor reproductive outcomes, there is great interest in defining the ion channels that regulate uterine excitability. In human myometrium, the Na<sup>+</sup> leak channel, non-selective (NALCN) contributes to a gadolinium-sensitive, Na<sup>+</sup>-dependent leak current. The aim of this study was to determine the role of NALCN in regulating uterine excitability and examine its involvement in parturition. <b><i>Methods:</i></b> Wildtype C57BL/6J mice underwent timed-mating and NALCN uterine expression was measured at several time points across pregnancy including pregnancy days 7, 10, 14, 18 and 19. Sharp electrode current clamp was used to measure uterine excitability at these same time points. To determine NALCNâs contribution to myometrial excitability and pregnancy outcomes, we created smooth-muscle-specific NALCN knockout mice by crossing NALCN<i>fx/fx</i> mice with myosin heavy chain Cre (MHC<i>CreeGFP</i>) mice. Parturition outcomes were assessed by observation via surveillance video recording cre control, flox control, smNALCN<sup>+/-</sup>, and smNALCN<sup>-/-</sup> mice. Myometrial excitability was compared between pregnancy day 19 flox controls and smNALCN<sup>-/-</sup> mice. <b><i>Results:</i></b> We found that in the mouse uterus, NALCN protein levels were high early in pregnancy, decreased in mid and late pregnancy, and then increased in labor and postpartum. Sharp electrode current clamp recordings of mouse longitudinal myometrial samples from pregnancy days 7, 10, 14, 18, and 19 revealed day-dependent increases in burst duration and interval and decreases in spike density. NALCN smooth muscle knockout mice had reduced myometrial excitability exemplified by shortened action potential bursts, and an increased rate of abnormal labor, including prolonged and dysfunctional labor. <b><i>Conclusions:</i></b> Together, our findings demonstrate that the Na<sup>+</sup> conducting channel NALCN contributes to the myometrial action potential waveform and is important for successful labor outcomes