Fabrication of super-hydrophobic nickel film on copper substrate with improved corrosion inhibition by electrodeposition process

Inspired by the famous “lotus effect”, we have fabricated the super-hydrophobic surfaces with nickel film on copper substrates using a one-step electrodeposition method. By adjusting processing time, water contact angle of as-prepared surfaces can reach as high as 160.3 ± 1.5° with small rolling angle of 3.0 ± 0.5°, showing excellent super-hydrophobicity. After the deposition of nickel coating, the pristine copper surfaces became much rough with packed cauliflower-/thorn-like clusters. This unique surface texture contributed to trapping large amount of air and forming the air cushion underneath the water droplet, which can prevent the liquids contacting the copper substrate. The examination of surface chemical compositions implied that the deposited super-hydrophobic coating consisted of nickel crystals and nickel myristate. In this research, the formation mechanism of the electrodeposited super-hydrophobicity was extensively explained based on the analyses of surface texture and surface chemistry. Moreover, the corrosion resistance of the as-fabricated super-hydrophobic surface was estimated by the potentiodynamic polarization tests as well as the electrochemical impedance spectroscopy (EIS) measurements. The results demonstrate that the super-hydrophobic nickel coating showed excellent corrosion inhibition in simulated seawater solution. The existence of the super-hydrophobic coating could be regarded as a barrier and thus provide a perfect air-liquid interface that inhibits the penetration of the corrosive ions. This facile and effective method of electrodeposition process offers a promising approach for mass production of super-hydrophobic surfaces on various metals

Status of the ACCULINNA-2 project at FLNR

The project of a new and more powerful in-flight fragment separator ACCULINNA-2 at U-400M cyclotron in FLNR, JINR planned to build in addition to the existing separator ACCULINNA is presented. The new separator will provide high intensity RIBs in the lowest energy range (5÷50 MeV/nucleon) which is attainable for in-flight separators. The possibilities for the astrophysics studies at the proposed device are presented. ACCULINNA-2 separator is planned to be constructed in the years 2010-2015. The current status of the project is reported

Elevated temperature lasing from injection microdisk lasers on silicon

The combination of high operation temperatures and small diode lasers directly grown on silicon substrates is essential for their application in future photonic integrated circuits. In this letter, results are presented for quantum dot III–V-on-Si microdisk diode lasers tested at elevated temperatures. To the best of our knowledge, we have demonstrated the first uncooled microlasers with diameter of 30 µm capable of operating in the continuous wave regime at 60 °C. In the lasing regime, the emission spectra contain one very intense line with a full-width at half-maximum of 30 pm; the side mode suppression ratio reaches 18 dB. Because of self-heating, the actual temperature of the active region is close to 100 °C. Under pulsed excitation, the maximal lasing temperature is 110 °C

Optical identification of electronic state levels of an asymmetric InAs/InGaAs/GaAs dot-in-well structure

We have studied the electronic state levels of an asymmetric InAs/InGaAs/GaAs dot-in-well structure, i.e., with an In0.15Ga0.85As quantum well (QW) as capping layer above InAs quantum dots (QDs), via temperature-dependent photoluminescence, photo-modulated reflectance, and rapid thermal annealing (RTA) treatments. It is shown that the carrier transfer via wetting layer (WL) is impeded according to the results of temperature dependent peak energy and line width variation of both the ground states (GS) and excited states (ES) of QDs. The quenching of integrated intensity is ascribed to the thermal escape of electron from the dots to the complex In0.15Ga0.85As QW + InAs WL structure. Additionally, as the RTA temperature increases, the peak of PL blue shifts and the full width at half maximum shrinks. Especially, the intensity ratio of GS to ES reaches the maximum when the energy difference approaches the energy of one or two LO phonon(s) of InAs bulk material, which could be explained by phonon-enhanced inter-sublevels carrier relaxation in such asymmetric dot-in-well structure

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO

Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s√=8 TeV with the ATLAS detector

The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1fb−1 of proton–proton collision data at √s = 8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t˜→tχ˜01 or t˜→ bχ˜±1 →bW(∗)χ˜01 , where χ˜01 (χ˜±1 ) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t˜ → tχ˜01 . For a branching fraction of 100%, top squark masses in the range 270–645 GeV are excluded for χ˜01 masses below 30 GeV. For a branching fraction of 50% to either t˜ → tχ˜01 or t˜ → bχ˜±1 , and assuming the χ˜±1 mass to be twice the χ˜01 mass, top squark masses in the range 250–550 GeV are excluded for χ˜01 masses below 60 GeV

Compressed representation of a partially defined integer function over multiple arguments

In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one