1,847 research outputs found
Graphene coatings: An efficient protection from oxidation
We demonstrate that graphene coating can provide an efficient protection from
oxidation by posing a high energy barrier to the path of oxygen atom, which
could have penetrated from the top of graphene to the reactive surface
underneath. Graphene bilayer, which blocks the diffusion of oxygen with a
relatively higher energy barrier provides even better protection from
oxidation. While an oxygen molecule is weakly bound to bare graphene surface
and hence becomes rather inactive, it can easily dissociates into two oxygen
atoms adsorbed to low coordinated carbon atoms at the edges of a vacancy. For
these oxygen atoms the oxidation barrier is reduced and hence the protection
from oxidation provided by graphene coatings is weakened. Our predictions
obtained from the state of the art first-principles calculations of electronic
structure, phonon density of states and reaction path will unravel how a
graphene can be used as a corrosion resistant coating and guide further studies
aiming at developing more efficient nanocoatings.Comment: under review in PRB;
http://link.aps.org/doi/10.1103/PhysRevB.85.15544
Resonant production of diquarks at high energy pp, ep and e+e- colliders
Resonant productions of the first generation scalar and vector diquarks at
high energy hadron-hadron (pp), lepton-hadron (ep) and lepton-lepton (e+e-)
colliders are investigated. Taking into account the hadronic component of the
photon, diquarks can be produced resonantly in the lepton-hadron and
lepton-lepton collisions. Production rates, decay widths and signatures of
diquarks are discussed using the general, SU(3)_{C} x SU(2)_{W} x U(1)_{Y}
invariant, effective Lagrangian. The corresponding dijet backgrounds are
examined in the interested invariant mass regions. The attainable mass limits
and couplings are obtained for the diquarks that can be produced in hadron
collisions and in resolved photon processes. It is shown that hadron collider
with center of mass energy sqrt(s)=14 TeV will be able to discover scalar and
vector diquarks with masses up to m_{DQ}=9 TeV for quark-diquark-quark coupling
alpha_{DQ}=0.1. Relatively, lighter diquarks can be probed at ep and e+e-
collisions in more clear environment.Comment: 12 pages, 12 figures, 6 table
Adsorption and absorption of Boron, Nitrogen, Aluminium and Phosphorus on Silicene: stability, electronic and phonon properties
Ab initio calculations within the density-functional theory formalism are
performed to investigate the chemical functionalization of a graphene-like
monolayer of silicon - silicene - with B, N, Al or P atoms. The structural,
electronic, magnetic and vibrational properties are reported. The most
preferable adsorption sites are found to be valley, bridge, valley and hill
site for B, N, Al and P adatoms, respectively. All the relaxed systems with
adsorbed/substituted atoms exhibit metallic behaviour with strongly bonded B,
N, Al, and P atoms accompanied by an appreciable electron transfer from
silicene to the B, N and P adatom/substituent. The Al atoms exhibit opposite
charge transfer, with n-type doping of silicene and weaker bonding. The
adatoms/substituents induce characteristic branches in the phonon spectrum of
silicene, which can be probed by Raman measurements. Using molecular dynamics
we found that the systems under study are stable up to at least T = 500 K. Our
results demonstrate that silicene has a very reactive and functionalizable
surface.Comment: 9 pages, 5 figure
The effect of electromagnetic properties of neutrinos on the photon-neutrino decoupling temperature
We examine the impact of electromagnetic properties of neutrinos on the
annihilation of relic neutrinos with ultra high energy cosmic neutrinos for the
process. For this process, photon-neutrino
decoupling temperature is calculated via effective lagrangian model beyond the
standard model. We find that photon-neutrino decoupling temperature can be
importantly reduced below the QCD phase transition with the model independent
analysis defining electromagnetic properties of neutrinos.Comment: 12 pages, 3 figures, published versio
Unparticle Physics in the Moller Scattering
We investigate the virtual effects of vector unparticles in the Moller
scattering. We derive the analytic expression for scattering amplitudes with
unpolarized beams. We obtain 95% confidence level limits on the unparticle
couplings and with integrated luminosity of
and and 500 GeV energies. We show
that limits on are more sensitive than .Comment: 10 pages, 5 figures, 4 table
An elementary optical gate for expanding entanglement web
We introduce an elementary optical gate for expanding polarization entangled
W states, in which every pair of photons are entangled alike. The gate is
composed of a pair of 50:50 beamsplitters and ancillary photons in the
two-photon Fock state. By seeding one of the photons in an -photon W state
into this gate, we obtain an -photon W state after post-selection. This
gate gives a better efficiency and a simpler implementation than previous
proposals for -state preparation.Comment: 5 pages, 2 figures. To appear in Phys. Rev.
Demonstration of local expansion toward large-scale entangled webs
We demonstrate an optical gate that increases the size of polarization-based
W states by accessing only one of the qubits. Using this gate, we have
generated three-photon and four-photon W states with fidelities and , respectively. We also confirmed existence of pairwise
entanglement in every pair of the qubits including the one that was left
untouched by the gate. The gate is applicable to any size of W states and hence
is a universal tool for expanding entanglement.Comment: 5 pages, 4 figure
COVID-19 Pandemi Sırasındaki Acil Cerrahi Bakım ve Ameliyathane Uygulamalarında Perioperatif Uygulama ve Rehberlik; Deneyimlerimiz
Aim: The novel coronavirus SARS-CoV-2 (COVID-19) can infect healthcare workers. We developed an institutional algorithm to protect operating room team members during the COVID-19 pandemic and rationally conserve personal protective equipment (PPE). We aimed to review the latest data on the COVID-19 pandemic and essential information for practice in emergency surgery and the operating room.Materials and Methods: An interventional platform (operating room, interventional suite, and endoscopy) with our committee formed with our doctors consisting of different branches, we developed our guidelines based on potential patterns of spread, risk of exposure, and conservation of PPE. We aimed to share our experiences with 128 patients who were taken into operation in a 2-month period.Anesthetic management and infection control guidelines for emergency procedures for patients with suspected 2019-nCoV were drafted and applied in Medical Faculty of Namık Kemal University.Results: A decision tree algorithm describing our institutional guidelines for precautions for operating room team members was created. This algorithm is based on the urgency of operation, anticipated viral burden at the surgical site, the opportunity for a procedure to aerosolize virus, and the likelihood a patient could be infected based on symptoms and testing.Conclusion: Despite COVID-19 being a new threat, we have shown that by developing an easy-to-follow decision algorithm for the interventional platform teams, we can ensure optimal healthcare worker safety.Amaç: Yeni koronavirüs SARS-CoV-2 (COVID-19) sağlık çalışanlarını enfekte edebilir. COVID-19 salgını sırasında ameliyathane ekip üyelerini korumak ve rasyonel olarak kişisel koruyucu ekipman (KKE) için kurumsal bir algoritma geliştirdik. Acil cerrahi ve ameliyathanede COVID-19 salgını ile ilgili en güncel bilgileri gözden geçirmeyi amaçladık. Materyal ve Metot: Farklı branşlardan oluşan doktorlarımızla oluşturduğumuz komitemiz ile girişimsel bir platform (ameliyathane, girişimsel ve endoskopi), potansiyel yayılma örüntüleri, maruz kalma riski ve KKE'nin korunmasına dayanan kılavuzlarımızı geliştirdik. Deneyimlerimizi 2 aylık bir sürede ameliyat edilen 128 hasta ile paylaşmayı amaçladık. 2019-nCoV şüphesi olan hastalar için acil durum prosedürleri için anestezi yönetimi ve enfeksiyon kontrol kılavuzları Namık Kemal Üniversitesi Tıp Fakültesi'nde hazırlanmış ve uygulanmıştır. Bulgular: Ameliyathane ekibi üyelerine yönelik önlemler için kurumsal yönergelerimizi açıklayan bir karar algoritması oluşturuldu. Bu algoritma ameliyatın aciliyetine, cerrahi bölgede beklenen viral yüke, virüsü aerosol haline getirme prosedürü fırsatına ve hastanın semptomlara ve testlere dayanarak enfekte olma olasılığına dayanır. Sonuç: COVID-19'un yeni bir tehdit olmasına rağmen, girişimsel platform ekipleri için izlemesi kolay bir karar algoritması geliştirerek, optimum sağlık çalışanı güvenliğini sağlayabildiğimizi gösterdik
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