1,497 research outputs found
Unit cell of graphene on Ru(0001): a 25 x 25 supercell with 1250 carbon atoms
The structure of a single layer of graphene on Ru(0001) has been studied
using surface x-ray diffraction. A surprising superstructure has been
determined, whereby 25 x 25 graphene unit cells lie on 23 x 23 unit cells of
Ru. Each supercell contains 2 x 2 crystallographically inequivalent subcells
caused by corrugation. Strong intensity oscillations in the superstructure rods
demonstrate that the Ru substrate is also significantly corrugated down to
several monolayers, and that the bonding between graphene and Ru is strong and
cannot be caused by van der Waals bonds. Charge transfer from the Ru substrate
to the graphene expands and weakens the C-C bonds, which helps accommodate the
in-plane tensile stress. The elucidation of this superstructure provides
important information in the potential application of graphene as a template
for nanocluster arrays.Comment: 9 pages, 3 figures, paper submitted to peer reviewed journa
The picture of the Bianchi I model via gauge fixing in Loop Quantum Gravity
The implications of the SU(2) gauge fixing associated with the choice of
invariant triads in Loop Quantum Cosmology are discussed for a Bianchi I model.
In particular, via the analysis of Dirac brackets, it is outlined how the
holonomy-flux algebra coincides with the one of Loop Quantum Gravity if paths
are parallel to fiducial vectors only. This way the quantization procedure for
the Bianchi I model is performed by applying the techniques developed in Loop
Quantum Gravity but restricting the admissible paths. Furthermore, the local
character retained by the reduced variables provides a relic diffeomorphisms
constraint, whose imposition implies homogeneity on a quantum level. The
resulting picture for the fundamental spatial manifold is that of a cubical
knot with attached SU(2) irreducible representations. The discretization of
geometric operators is outlined and a new perspective for the super-Hamiltonian
regularization in Loop Quantum Cosmology is proposed.Comment: 6 page
PETITION FOR RECONSIDERATION OF INVESTIGATION ORDER1
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Copper deficiency anemia after bariatric surgery
Copper is a trace mineral essential to hematopoiesis and to the structure and function of the nervous system. Copper acts as a ligand to ferroxidase II, which oxidizes iron, allowing it to be mobilized and transported from the hepatic stores to the bone marrow to be used in erythropoiesis..Copper deficiency is a rare cause of anemia, leukopenia, and myeloneuropathy. In this report we describe a case of a 49 year-old overweight Caucasian woman who was referred June 2008 to the Obesity Outpatient Clinic at UNIFESP for evaluation of muscular pain and weakness in both legs, fatigue and chronic anemia. The past medical history included Scopinaro Surgery for severe obesity in November 2004 when her weight was approximately 180 Kg (BMI 68.6 kg/m2). She lost considerable weight after surgery, with her weight being stable around 80 kg (BMI 30). Because of clinical manifestations of sub nutrition, protein and vitamin deficiencies and severe anemia, which lead to several hospital admissions, in February 2008 she was submitted to another surgery from conversion of the gastrointestinal surgical Scopinaro procedure to that performed by Capella. She also had a history of hypothyroidism, hyperuricemia and panic syndrome, requiring specific medications, beyond parenteral iron and B12 vitamin therapies for anemia. Physical examination revealed a bilateral edema and no other abnormality. Laboratory tests revealed hypoalbuminemia and hypochromic megaloblastic anemia with normal serum levels of B12 vitamin, iron and ferritin. Due to the persistence of the neurologic symptoms and anemia in spite of adequate iron and B12 vitamin therapies, the hypothesis of copper deficiency was considered and a low serum level of 40μg/dl was found. An oral supplementation with high doses of copper resulted in evident clinical and laboratorial improvements after eight weeks of therapy. The diagnosis of copper deficiency has to be part of the differential diagnosis in patients with unexplained neurologic symptoms, anemia, and leukopenia, especially in those who underwent to previous gastrointestinal surgery
Aluminum(III) Salen Complexes as Active Photoredox Catalysts
Metallosalen are privileged complexes that have found important applications in catalysis. In addition, their luminescent properties have also been studied and used for sensing and biological applications. Salen metal complexes can be efficient photosensitizers, but they can also participate to electron transfer processes. Indeed, we have found that commercially available [Al(Salen)Cl] is an efficient photoredox catalyst for the synergistic stereoselective reaction of alkyl aldehydes with different bromo ketones and malonates to give the corresponding enantioenriched α-alkylated derivatives. The reaction was performed in the presence of a MacMillan catalyst. [Al(Salen)Cl] is able to replace ruthenium complexes, showing that also aluminum complexes can be used in promoting photoredox catalytic reactions
Classification of non-indigenous species based on their impacts: Considerations for application in marine management
Assessment of the ecological and economic/societal impacts of the introduction of non-indigenous species (NIS) is one of the primary focus areas of bioinvasion science in terrestrial and aquatic environments, and is considered essential to management. A classification system of NIS, based on the magnitude of their environmental impacts, was recently proposed to assist management. Here, we consider the potential application of this classification scheme to the marine environment, and offer a complementary framework focussing on value sets in order to explicitly address marine management concerns. Since existing data on marine NIS impacts are scarce and successful marine removals are rare, we propose that management of marine NIS adopt a precautionary approach, which not only would emphasise preventing new incursions through pre-border and at-border controls but also should influence the categorisation of impacts. The study of marine invasion impacts requires urgent attention and significant investment, since we lack the luxury of waiting for the knowledge base to be acquired before the window of opportunity closes for feasible management
Synthesis, Structure, Photophysics, and Singlet Oxygen Sensitization by a Platinum(II) Complex of Meso-Tetra-Acenaphthyl Porphyrin
A new platinum(II) porphyrin complex has been synthesized and characterized via various spectroscopic techniques. Single-crystal XRD analysis reveals that the geometry around the Pt(II) center is near the perfect square planar geometry. The Pt(II)−N bond distances are in the ranges of 2.005 Å–2.020 Å. The platinum(II) porphyrin derivative exhibited one reversible oxidative couple at +1.10 V and a reversible reductive couple at −1.47 V versus Ag/AgCl. In deaerated dichloromethane solution at 298 K, a strong phosphorescence is observed at 660 nm, with emission quantum yield of 35 % and lifetime of 75 μs. Upon excitation of the acenaphthene chromophores at 300 nm, sensitised phosphorescence of the Pt(II) porphyrin is observed with a unitary efficient energy transfer, demonstrating that this system behaves as a light harvesting antenna. The red phosphorescence is strongly quenched by oxygen, resulting in singlet oxygen production with a very high quantum yield of 88 %. This result indicates that this Pt(II) porphyrin is an excellent photosensitizer for the production of singlet oxygen and will have potential applications in the field of photodynamic therapy as well as oxygen sensors
The enlargement of the Suez Canal and introduction of non-indigenous species to the Mediterranean Sea
The Suez Canal is one of the most important waterways in the world – during the last year 17,148 ships passed through the Canal – reducing emissions, saving time, and operating costs to shippers. The rapid increase in ship size from the “Post-Suezmax” (> 12,000 TEU) to the latest container vessels (> 19,000 TEU) now requires enlargements of port facilities and canals.
A project of this magnitude, and with potentially negative environmental outcomes, requires a transparent and scientifically sound “Environmental Impact Assessment” (EIA). An explicit obligation on Parties to the Convention on Biological Diversity (https://www.cbd.int/doc/ legal/cbd-en.pdf) was made to consider transboundary impacts on biodiversity, particularly those associated with invasive non-indigenous species
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