862 research outputs found
Electronic structure of C60 / graphite
We report temperature-dependent photoelectron spectra for a monolayer of C_60
adsorbed on HOPG, as well as C 1s x-ray absorption. This extends a previous
report which showed the close similarity between the spectrum of the HOMO for
the two-dimensional overlayer and that of C_60 in the gas phase. The present
work shows that intermolecular and molecule-substrate vibrations contribute
strongly to the spectral lineshape at room temperature. Thus, vibrational
effects are shown to be crucial for the proper understanding of photoelectron
spectra, and thus the charge transport properties, for C_60 in contact with
graphite and graphite-like materials.Comment: Proc. of the XV. Int. Winterschool on Electronic Properties of Novel
Materials, Kirchberg/Tirol, Austria, 200
GEOTHERMAL EXPLORATION IN THE ALEXANDRIA AREA, THESSALONIKI BASIN (MACEDONIA, NORTHERN GREECE)
Η περιοχή της Αλεξάνδρειας βρίσκεται στη Λεκάνη Θεσσαλονίκης, η οποία έχει πληρωθεί με ιζήματα πάχους άνω των 4 km. To 1980, κατασκευάσθηκε βόρεια της πόλης της Αλεξάνδρειας η γεώτρηση έρευνας υδρογονανθράκων AL-1, βάθους 1705 m, στην οποία καταγράφηκαν οι θερμοκρασίες των 39 και 65oC σε βάθη 700 και 1705 m αντίστοιχα. Μεταξύ 1996 και 2000, ανορύχθηκαν δύο γεωθερμικές ερευνητικές γεωτρήσεις, βάθους 532 και 620 m, οι οποίες διέτρησαν Τεταρτογενή και Πλειοκαινικά ιζήματα και στις οποίες μετρήθηκαν θερμοκρασίες 30.1 και 33.4oC σε βάθη 500 και 611 m αντίστοιχα. Η προκαταρκτική γεωθερμική έρευνα οδήγησε την κατασκευή της πρώτης παραγωγικής γεώτρησης (ΓΝ-1Π). Ανορύχθηκε μέχρι βάθος 805 m διατρύοντας αργίλους, άμμους, τόφφους, μάργες, αργιλο-μάργες, μαργαϊκούς ασβεστόλιθους, χάλικες, ψαμμίτες και κροκαλοπαγή. Η γεώτρηση σωληνώθηκε μέχρι τα 805 m και φίλτρα τοποθετήθηκαν σε διάφορα βάθη κάτω από τα 607 m. Τιμές θερμοκρασίας και ηλεκτρικής αγωγιμότητας 35.1-37.2oC και 5100-8200 μS/cmαντίστοιχα καταγράφηκαν σε βάθη 607-800 m. Η γεώτρηση παρουσιάζει αρτεσιανή ροή με 30-40 m3/h νερών των 34.1oC και παρέχει με άντληση 130 m3/h νερών θερμοκρασίας 35.5oC. Το παραγόμενο γεωθερμικό νερό με ΣΔΑ 2.18 g/l είναι του τύπου Na-Cl και διαφοροποιείται από τα ρηχά νερά. Η θερμική ισχύς της γεώτρησης ΓΝ-1Π υπολογίζεται σε 1.65 MWt.The area of Alexandria is located in the Thessaloniki basin that has been filled with more than 4 km of sediments. In 1980, oil exploration borehole AL-1, 1,705 m deep, was drilled north of the town of Alexandria and the temperatures of 39 and 65oC were recorded at depths of 700 and 1,705 m respectively. During 1996-2000, two geothermal exploration boreholes were drilled at depths of 532 and 620 m penetrating Quaternary and Pliocene sediments and the temperatures of 30.1 and 33.4oC were measured at 500 and 611 m respectively. The preliminary geothermal investigation resulted in the construction of the first production well (GN-1P). It was drilled to a depth of 805 m penetrating clays, sands, tuffs, marls, clayey marls, marly limestones, gravels, sandstones and conglomerates. The borehole was cased down to 805 m and screens were placed at various depths below 607 m. Temperature and electrical conductivity values of 35.1-37.2oC and 5,100-8,200 μS/cm respectively were recorded at depths of 607-800 m. This well discharges 30-40 m3/h waters at 34.1oC with artesian flow and provides 130 m3/h waters at 35.5oC with pumping. The produced geothermal water with TDS of 2.18 g/l belongs to the Na-Cl type differentiated from the shallow waters. The thermal capacity of well GN-1P is calculated to be 1.65 MWt
Dynamic range and mass accuracy of wide-scan direct infusion nanoelectrospray fourier transform ion cyclotron resonance mass spectrometry-based metabolomics increased by the spectral stitching method
Direct infusion nanoelectrospray Fourier transform ion cyclotron resonance mass spectrometry (DI nESI FT-ICR MS)offers high mass accuracy and resolution for analyzing complex metabolite mixtures. High dynamic range across a wide mass range, however, can only be achieved at the expense of mass accuracy, since the large numbers of ions entering the ICR detector induce adverse spacecharge effects. Here we report an optimized strategy for wide-scan DI nESI FT-ICR MS that increases dynamic range but maintains high mass accuracy. It comprises the collection if multiple adjacent selected ion monitoring (SIM) windows that are stitched together using novel algorithms. The final SIM-stitching method, derived from several optimization experiments, comprises 21 adjoining SIM windows each of width m/z 30 (from m/z 70 to 500; adjacent windows overlap by m/z 10) with an automated gain control (AGC) target of 1 105 charges. SIMstitching and wide-scan range (WSR; Thermo Electron)were compared using a defined standard to assess mass accuracy and a liver extract to assess peak count and dynamic range. SIM-stitching decreased the maximum mass error by 1.3- and 4.3-fold, and increased the peak count by 5.3- and 1.8-fold, versus WSR (AGC targets of 1 x 105 and 5 x 105, respectively). SIM-stitching achieved an rms mass error of 0.18 ppm and detected over 3000 peaks in liver extract. This novel approach increases metabolome coverage, has very high mass accuracy, and at 5.5 min/sample is conducive for high- throughput metabolomics
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Collaboration and contract management in the context of offshore oil and gas contracts - an English law analysis
This thesis provides an English law analysis on collaboration and contract management in the context of offshore upstream oil and gas contracts in light of the Maximising Economic Recovery [hereinafter ‘MER’] Strategy. The predominant subject of the thesis is the impact on offshore contracting of the MER Strategy. The thesis firstly considers that the Strategy is not merely another statute to regulate the offshore sector – its impact is of paramount importance because it sets a comprehensive framework for the coming decades until the cessation of operations in the North Sea. The MER Strategy seeks to address the field ‘maturity’ in the North Sea, which causes high extraction costs and questions the current business and contracting model. Secondly, the thesis focuses on the contracting model and relationship among operators and contractors, i.e. oil and gas companies and the supply chain. This niche area of contract law has been in the spotlight of academics and practitioners for many years, and abundant literature exists focusing on so-called ‘risk allocation’ clauses. However, the thesis approaches the subject in an original manner: looking beyond the traditional legal standpoint, it introduces the element of ‘contract and commercial management’ and focuses on the potential of ‘collaboration’. It argues that these two elements are key to the future of offshore contracting in light of the MER Strategy. The explanation of where these two terms ‘sit’ from an academic, practical and taxonomic standpoint is not an easy task. Contract and commercial management is a management-based discipline that goes beyond certain limitations imposed on the role of contract, championed by ‘strict’ school of thoughts on contract law. It perceives the contract to be mainly a device of ‘problem solving’ rather than ‘failure management’. Collaboration is a notion with great potential for contracting in general – and offshore contracting in particular – which nevertheless brings with it substantial challenges that need to be addressed. Collaboration is a crucial concept in the MER Strategy, and the thesis seeks to ascertain its meaning both within and beyond the context of the Strategy. Most importantly, the thesis explores the legal meaning and ramifications of collaboration, since although it is not a legal term of art, it is ‘reflected’ on existing doctrinal notions
Element specific characterization of heterogeneous magnetism in (Ga,Fe)N films
We employ x-ray spectroscopy to characterize the distribution and magnetism
of particular alloy constituents in (Ga,Fe)N films grown by metal organic vapor
phase epitaxy. Furthermore, photoelectron microscopy gives direct evidence for
the aggregation of Fe ions, leading to the formation of Fe-rich nanoregions
adjacent to the samples surface. A sizable x-ray magnetic circular dichroism
(XMCD) signal at the Fe L-edges in remanence and at moderate magnetic fields at
300 K links the high temperature ferromagnetism with the Fe(3d) states. The
XMCD response at the N K-edge highlights that the N(2p) states carry
considerable spin polarization. We conclude that FeN{\delta} nanocrystals, with
\delta > 0.25, stabilize the ferromagnetic response of the films.Comment: 4 pages, 3 figures, 1 tabl
Optimized Perturbation Theory for Wave Functions of Quantum Systems
The notion of the optimized perturbation, which has been successfully applied
to energy eigenvalues, is generalized to treat wave functions of quantum
systems. The key ingredient is to construct an envelope of a set of
perturbative wave functions. This leads to a condition similar to that obtained
from the principle of minimal sensitivity. Applications of the method to
quantum anharmonic oscillator and the double well potential show that uniformly
valid wave functions with correct asymptotic behavior are obtained in the
first-order optimized perturbation even for strong couplings.Comment: 11 pages, RevTeX, three ps figure
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