385 research outputs found
Comparison of methods for determining the fatty acid composition of photosynthetic tissues
The fatty acid (FA) composition of photosynthetic tissue differs from that in other plant or animal tissues. In leaves, the lipid fraction constitutes less than 10% of the dry weight and is mostly located in the chloroplasts. An extraction solvent should dissolve polar lipids readily, but should also overcome interactions between the lipids and the tissue matrix. A mixture of chloroform/methanol (C/M) is commonly used. However, less toxic alternative methods such as hexane/isopropanol (H/I) and ethanol (E) have been suggested. In this preliminary study we compared the effectiveness of these three methods which are used as standard extraction protocols for FA analysis of plant material at three different European Universities. C/M extraction gave the highest total FA content and H/I the lowest, suggesting that C/M is indeed the best general-purpose lipid extraction solvent. Significant differences were also observed for FA composition including the ratio of saturated to unsaturated FA indicating selectivity of the various solvents in extracting different individual FA. Further and more detailed investigations are required to confirm this hypothesi
Imaging of focal seizures with Electrical Impedance Tomography and depth electrodes in real time
Intracranial EEG is the current gold standard technique for localising seizures for surgery, but it can be insensitive to tangential dipole or distant sources. Electrical Impedance Tomography (EIT) offers a novel method to improve coverage and seizure onset localisation. The feasibility of EIT has been previously assessed in a computer simulation, which revealed an improved accuracy of seizure detection with EIT compared to intracranial EEG. In this study, slow impedance changes, evoked by cell swelling occurring over seconds, were reconstructed in real time by frequency division multiplexing EIT using depth and subdural electrodes in a swine model of epilepsy. EIT allowed to generate repetitive images of ictal events at similar time course to fMRI but without its significant limitations. EIT was recorded with a system consisting of 32 parallel current sources and 64 voltage recorders. Seizures triggered with intracranial injection of benzylpenicillin (BPN) in five pigs caused a repetitive peak impedance increase of 3.4±1.5 mV and 9.5±3% (N=205 seizures); the impedance signal change was seen already after a single, first seizure. EIT enabled reconstruction of the seizure onset 9±1.5 mm from the BPN cannula and 7.5±1.1 mm from the closest SEEG contact (p<0.05, n=37 focal seizures in three pigs) and it could address problems with sampling error in intracranial EEG. The amplitude of the impedance change correlated with the spread of the seizure on the SEEG (p <0.001, n=37). The results presented here suggest that combining a parallel EIT system with intracranial EEG monitoring has a potential to improve the diagnostic yield in epileptic patients and become a vital tool in improving our understanding of epilepsy
Solitons as the early stage of quasicondensate formation during evaporative cooling
We calculate the evaporative cooling dynamics of trapped one-dimensional
Bose-Einstein condensates for parameters leading to a range of condensates and
quasicondensates in the final equilibrium state. We confirm that solitons are
created during the evaporation process, but always eventually dissipate during
thermalisation. The distance between solitons at the end of the evaporation
ramp matches the coherence length in the final thermal state. Calculations were
made using the classical fields method. They bridge the gap between the phase
defect picture of the Kibble-Zurek mechanism and the long-wavelength phase
fluctuations in the thermal state
Non-diffusive phase spreading of a Bose-Einstein condensate at finite temperature
We show that the phase of a condensate in a finite temperature gas spreads
linearly in time at long times rather than in a diffusive way. This result is
supported by classical field simulations, and analytical calculations which are
generalized to the quantum case under the assumption of quantum ergodicity in
the system. This super-diffusive behavior is intimately related to conservation
of energy during the free evolution of the system and to fluctuations of energy
in the prepared initial state.Comment: 16 pages, 7 figure
Increased NBCn1 expression, Na+/HCO3- co-transport and intracellular pH in human vascular smooth muscle cells with a risk allele for hypertension.
Genome-wide association studies have revealed an association between variation at the SLC4A7 locus and blood pressure. SLC4A7 encodes the electroneutral Na+/HCO3- co-transporter NBCn1 which regulates intracellular pH (pHi). We conducted a functional study of variants at this locus in primary cultures of vascular smooth muscle and endothelial cells. In both cell types, we found genotype-dependent differences for rs13082711 in DNA-nuclear protein interactions, where the risk allele is associated with increased SLC4A7 expression level, NBCn1 availability and function as reflected in elevated steady-state pHi and accelerated recovery from intracellular acidosis. However, in the presence of Na+/H+âexchange activity, the SLC4A7 genotypic effect on net base uptake and steady-state pHi persisted only in vascular smooth muscle cells but not endothelial cells. We found no discernable effect of the missense polymorphism resulting in the amino acid substitution Glu326Lys. The finding of a genotypic influence on SLC4A7 expression and pHi regulation in vascular smooth muscle cells provides an insight into the molecular mechanism underlying the association of variation at the SLC4A7 locus with blood pressure
Antimony substituted lanthanum orthoniobate proton conductor - Structure and electronic properties
Xâray and neutron diffraction have been utilized to analyze the crystalline and electronic structure of lanthanum orthoniobate substituted by antimony. Using Xâray absorption spectroscopy and photoelectron spectroscopy, changes in the electronic structure of the material upon substitution have been analyzed. The structural transition temperature between fergusonite and scheelite phases for 30 mol% antimony substitution was found to be 15°C. Based on the neutron data, the oxygen nonstoichiometry was found to be relatively low. Moreover no influence on the position of the valence band maximum was observed. The influence of the protonation on the electronic structure of constituent oxides has been studied. Absorption data show that the incorporation of protonic defects into the lanthanum orthoniobate structure leads to changes in lanthanum electronic structure and a decrease in the density of unoccupied electronic states
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High-throughput isolation and characterization of untagged membrane protein complexes: outer membrane complexes of Desulfovibrio vulgaris.
Cell membranes represent the "front line" of cellular defense and the interface between a cell and its environment. To determine the range of proteins and protein complexes that are present in the cell membranes of a target organism, we have utilized a "tagless" process for the system-wide isolation and identification of native membrane protein complexes. As an initial subject for study, we have chosen the Gram-negative sulfate-reducing bacterium Desulfovibrio vulgaris. With this tagless methodology, we have identified about two-thirds of the outer membrane- associated proteins anticipated. Approximately three-fourths of these appear to form homomeric complexes. Statistical and machine-learning methods used to analyze data compiled over multiple experiments revealed networks of additional protein-protein interactions providing insight into heteromeric contacts made between proteins across this region of the cell. Taken together, these results establish a D. vulgaris outer membrane protein data set that will be essential for the detection and characterization of environment-driven changes in the outer membrane proteome and in the modeling of stress response pathways. The workflow utilized here should be effective for the global characterization of membrane protein complexes in a wide range of organisms
Classical fields method for a relativistic interacting Bose gas
We formulate a classical fields method for description of relativistic
interacting bosonic particles at nonzero temperatures. The method relays on the
assumption that at low temperatures the Bose field can be described by a
c-number function. We discuss a very important role of the cut-off momentum
which divides the field into dominant classical part and a small quantum
correction. We illustrate the method by studying a thermodynamics of
relativistic Bose field which dynamics is governed by the Klein-Gordon equation
with term responsible for interactions.Comment: 12 pages, 10 figure
MethOds and tools for comprehensive impact Assessment of the CCAM solutions for passengers and goods. D1.1: CCAM solutions review and gaps
Review of the state-of-the-art on Cooperative, Connected and Automated mobility use cases, scenarios, business models, Key Performance Indicators, impact evaluation methods, technologies, and user needs (for organisations & citizens)
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