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1.
  • Ambrosio, M, et al. (författare)
  • The MACRO detector at Gran Sasso
  • 2002
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 486:3, s. 663-707
  • Tidskriftsartikel (refereegranskat)abstract
    • MACRO was an experiment that ran in the Laboratori Nazionali del Gran Sasso from 1988 to 2000. Its principal goal was to observe magnetic monopoles or set significantly lower experimental flux limits than had been previously available in the velocity range from about beta = 10(-4) to unity. In addition it made a variety of other observations. Examples are: setting flux limits on other so far unobserved particles such as nuclearites and lightly ionizing particles, searching for WIMP annihilations in the Earth and the Sun and for neutrino bursts from stellar collapses in or near our Galaxy, and making measurements relevant to high energy muon and neutrino astronomy and of the flux of up-going muons as a function of nadir angle showing evidence for neutrino oscillations. The apparatus consisted of three principal types of detectors: liquid scintillator counters, limited streamer tubes, and nuclear track etch detectors. In addition, over part of its area it contained a transition radiation detector. The general design philosophy emphasized redundancy and complementarity. This paper describes the technical aspects of the complete MACRO detector, its operational performance, and the techniques used to calibrate it and verify its proper operation. It supplements a previously published paper which described the first portion of the detector that was built and operated. (C) 2002 Elsevier Science B.V. All rights reserved.
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2.
  • Adcox, K, et al. (författare)
  • PHENIX detector overview
  • 2003
  • Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 499:2-3, s. 469-479
  • Tidskriftsartikel (refereegranskat)abstract
    • The PHENIX detector is designed to perform a broad study of A-A, p-A, and p-p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed in other papers in this volume. The overall design parameters of the detector are presented. (C) 2002 Elsevier Science B.V. All rights reserved.
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3.
  • Adcox, K, et al. (författare)
  • Flow Measurements via Two-Particle Azimuthal Correlations in Au+Au Collisions at sqrt[sNN]=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 89
  • Tidskriftsartikel (refereegranskat)abstract
    • Two-particle azimuthal correlation functions are presented for charged hadrons produced in Au+Au collisions at the Relativistic Heavy Ion Collider (sqrt[sNN]=130 GeV). The measurements permit determination of elliptic flow without event-by-event estimation of the reaction plane. The extracted elliptic flow values (v2) show significant sensitivity to both the collision centrality and the transverse momenta of emitted hadrons, suggesting rapid thermalization and relatively strong velocity fields. When scaled by the eccentricity of the collision zone ε, the scaled elliptic flow shows little or no dependence on centrality for charged hadrons with relatively low pT. A breakdown of this ε scaling is observed for charged hadrons with pT >1.0 GeV/c.
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4.
  • Adler, SS, et al. (författare)
  • Double helicity asymmetry in inclusive midrapidity pi(0) production for polarized p+p collisions at root s=200 GeV
  • 2004
  • Ingår i: Physical Review Letters. - 1079-7114. ; 93:20: 202002
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a measurement of the double longitudinal spin asymmetry in inclusive pi(0) production in polarized proton-proton collisions at roots=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 0.27. The measurements are the first in a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at midrapidity, where next-to-leading-order perturbative quantum chromodynamic (NLO pQCD) calculations well describe the unpolarized cross section. The observed asymmetry is small and is compared to a NLO pQCD calculation with a range of polarized gluon distributions.
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5.
  • Adcox, K, et al. (författare)
  • Centrality dependence of the high (PT) charged hadron suppression in Au+Au collisions at root s(NN)=130 GeV
  • 2003
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 561:1-2, s. 82-92
  • Tidskriftsartikel (refereegranskat)abstract
    • PHENIX has measured the centrality dependence of charged hadron p(T) spectra from Au +An collisions at root(s)NN = 130 GeV The truncated mean p(T) decreases with centrality for p(T) > 2 GeV/c, indicating an apparent reduction of the contribution from hard scattering to high p(T) hadrdn production. For central collisions the yield at high p(T) is shown to be suppressed compared to binary nucleon-nucleon collision scaling of p + p, data. This suppression is monotonically increasing with centrality, but most of the change occurs below 30% centrality, i.e., for collisions with less than similar to140 participating nucleons. The observed p(T) and centrality dependence is consistent with the particle production predicted by models including hard scattering and subsequent energy loss of the scattered partons in the dense matter created in the collisions. (C) 2003 Published by Elsevier Science B.V.
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6.
  • Adcox, K, et al. (författare)
  • Event-by-event fluctuations in mean p(T) and mean E(T) in root s(NN)=130 GeVAu+Au collisions
  • 2002
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 66:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Distributions of event-by-event fluctuations of the mean transverse momentum and mean transverse energy near mid-rapidity have been measured in Au+Au collisions at roots(NN)=130 GeV at the Relativistic Heavy-Ion Collider. By comparing the distributions to what is expected for statistically independent particle emission, the magnitude of nonstatistical fluctuations in mean transverse momentum is determined to be consistent with zero. Also, no significant nonrandom fluctuations in mean transverse energy are observed. By constructing a fluctuation model with two event classes that preserve the mean and variance of the semi-inclusive p(T) or e(T) spectra, we exclude a region of fluctuations in roots(NN)=130 GeV Au+Au collisions.
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7.
  • Adcox, K, et al. (författare)
  • Measurement of Lambda and (Lambda)over-bar particles in Au plus Au collisions at root s(NN)=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 89:9
  • Tidskriftsartikel (refereegranskat)abstract
    • We present results on the measurement of Lambda and (&ULambda;) over bar production in Au+Au collisions at roots(NN)=130 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider. The transverse momentum spectra were measured for minimum bias and for the 5% most central events. The (&ULambda;) over bar/Lambda ratios are constant as a function of p(T) and the number of participants. The measured net Lambda density is significantly larger than predicted by models based on hadronic strings (e.g., HIJING) but in approximate agreement with models which include the gluon-junction mechanism.
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8.
  • Adcox, K, et al. (författare)
  • Measurement of single electrons and implications for charm production in Au+Au collisions at root(NN)-N-S=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 88:19
  • Tidskriftsartikel (refereegranskat)abstract
    • Transverse momentum spectra of electrons from Au+Au collisions at roots(NN) = 130 GeV have been measured at midrapidity by the PHENIX experiment at the Relativistic Heavy Ion Collider. The spectra show an excess above the background from photon conversions and light hadron decays. The electron signal is consistent with that expected from semileptonic decays of charm. The yield of the electron signal dN(e)/dy for p(T) > 0.8 GeV/c is 0.025 +/- 0.004(stat) +/- 0.010( syst) in central collisions, and the corresponding charm cross section is 380 +/- 60(stat) +/- 200(syst ) mub per binary nucleon-nucleon collision.
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9.
  • Adcox, K, et al. (författare)
  • Net charge fluctuations in Au+Au interactions root s(NN)=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 89
  • Tidskriftsartikel (refereegranskat)abstract
    • Data from Au+ Au interactions at s(NN)=130 GeV, obtained with the PHENIX detector at the Relativistic Heavy-Ion Collider, are used to investigate local net charge fluctuations among particles produced near midrapidity. According to recent suggestions, such fluctuations may carry information from the quark-gluon plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays.
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10.
  • Adcox, K, et al. (författare)
  • Suppression of hadrons with large transverse momentum in central Au+Au collisions at root s(NN)=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 88:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Transverse momentum spectra for charged hadrons and for neutral pions in the range 1 Gev/c < P-T < 5 GeV/c have been measured by the PHENIX experiment at RHIC in Au + Au collisions at rootS(NN) = 130 GeV. At high p(T) the spectra from peripheral nuclear collisions are consistent with scaling the spectra from p + p collisions by the average number of binary nucleon-nucleon collisions. The spectra from central collisions are significantly suppressed when compared to the binary-scaled p + p expectation, and also when compared to similarly binary-scaled peripheral collisions, indicating a novel nuclear-medium effect in central nuclear collisions at RHIC energies.
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11.
  • Adcox, K, et al. (författare)
  • Transverse-mass dependence of two-pion correlations in Au+Au collisions at root(NN)-N-S=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 88:19
  • Tidskriftsartikel (refereegranskat)abstract
    • Two-pion correlations in roots(NN) = 130 GeV Au+Au collisions at RHIC have been measured over a broad range of pair transverse momentum k(T) by the PHENIX experiment at RHIC. The k(T) dependent transverse radii are similar to results from heavy-ion collisions at roots(NN) = 4.1 , 4.9, and 17.3 GeV, whereas the longitudinal radius increases monotonically with beam energy. The ratio of the outwards to sidewards transverse radii (R-out/R-side) is consistent with unity and independent of k(T) .
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12.
  • Adler, SS, et al. (författare)
  • Bose-Einstein correlations of charged pion pairs in Au+Au collisions at root(NN)-N-s = 200 GeV
  • 2004
  • Ingår i: Physical Review Letters. - 1079-7114. ; 93:15
  • Tidskriftsartikel (refereegranskat)abstract
    • Bose-Einstein correlations of identically charged pion pairs were measured by the PHENIX experiment at midrapidity in Au+Au collisions at roots(NN)=200 GeV. The Bertsch-Pratt radius parameters were determined as a function of the transverse momentum of the pair and as a function of the centrality of the collision. Using the standard core-halo partial Coulomb fits, and a new parametrization which constrains the Coulomb fraction as determined from the unlike-sign pion correlation, the ratio R-out/R-side is within 0.8-1.1 for 0.25<<1.2 GeV/c. The centrality dependence of all radii is well described by a linear scaling in N-part(1/3), and R-out/R-side for similar to0.45 GeV/c is approximately constant at unity as a function of centrality.
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13.
  • Adler, SS, et al. (författare)
  • Elliptic flow of identified hadrons in Au+Au collisions at root s(NN)=200 GeV
  • 2003
  • Ingår i: Physical Review Letters. - 1079-7114. ; 91:18: 182301
  • Tidskriftsartikel (refereegranskat)abstract
    • The anisotropy parameter (v(2)), the second harmonic of the azimuthal particle distribution, has been measured with the PHENIX detector in Au+Au collisions at roots(NN)=200 GeV for identified and inclusive charged particle production at central rapidities (eta<0.35) with respect to the reaction plane defined at high rapidities (eta=3-4 ). We observe that the v(2) of mesons falls below that of (anti)baryons for p(T)>2 GeV/c, in marked contrast to the predictions of a hydrodynamical model. A quark-coalescence model is also investigated.
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14.
  • Adler, SS, et al. (författare)
  • J/psi production from proton-proton collisions at root s=200 GeV
  • 2004
  • Ingår i: Physical Review Letters. - 1079-7114. ; 92:5
  • Tidskriftsartikel (refereegranskat)abstract
    • J/psi production has been measured in proton-proton collisions at roots=200 GeV over a wide rapidity and transverse momentum range by the PHENIX experiment at the Relativistic Heavy Ion Collider. Distributions of the rapidity and transverse momentum, along with measurements of the mean transverse momentum and total production cross section are presented and compared to available theoretical calculations. The total J/psi cross section is 4.0+/-0.6(stat)+/-0.6(syst)+/-0.4(abs) mub. The mean transverse momentum is 1.80+/-0.23(stat)+/-0.16(syst) GeV/c.
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15.
  • Adler, SS, et al. (författare)
  • J/psi production in Au-Au collisions at root s(NN)=200 GeV
  • 2004
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 69:1
  • Tidskriftsartikel (refereegranskat)abstract
    • First results on charm quarkonia production in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The yield of J/psi's measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au-Au reactions at roots(NN) = 200 GeV is analyzed as a function of collision centrality. For this analysis we have studied 49.3x10(6) minimum bias Au-Au reactions. We present the J/psi invariant yield dN/dy for peripheral and midcentral reactions. For the most central collisions where we observe no signal above background, we quote 90% confidence level upper limits. We compare these results with our J/psi measurement from proton-proton reactions at the same energy. We find that our measurements are not consistent with models that predict strong enhancement relative to binary collision scaling.
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16.
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17.
  • Adler, SS, et al. (författare)
  • Scaling properties of proton and antiproton production in root s(NN)=200 GeV Au+Au collisions
  • 2003
  • Ingår i: Physical Review Letters. - 1079-7114. ; 91:17: 172301
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the yield of protons and antiprotons, as a function of centrality and transverse momentum, in Au+Au collisions at rootS(NN)=200 GeV measured at midrapidity by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider. In central collisions at intermediate transverse momenta (1.5
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18.
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19.
  • Adell, Gunnar C. E., 1953-, et al. (författare)
  • Apoptosis in rectal carcinoma : Prognosis and recurrence after preoperative radiotherapy
  • 2001
  • Ingår i: Cancer. - 0008-543X .- 1097-0142. ; 91:10, s. 1870-1875
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Rectal carcinoma is common, with considerable local recurrence and death rates. Preoperative radiotherapy and refined surgical techniques can improve local control. The aim of this study was to investigate the interaction between apoptosis and the outcome of rectal carcinoma, with and without short-term preoperative radiotherapy.METHODS: Specimens were from 162 patients from the Southeast Swedish Health Care region included in the Swedish Rectal Cancer Trial between 1987-1990. New sections from the paraffin blocks of the preoperative biopsies and the surgical specimens were examined for apoptosis using the terminal deoxynucleotidyl transferase mediated digoxigenin nick end labeling (TUNEL) method.RESULTS: The mean percentage of apoptotic cells was 0.3% (0-4%) and 1.1% (0-14.5%) for the preoperative biopsy and the surgical specimen, respectively. The authors analyzed the surgical specimens from nonirradiated patients and divided them into three groups by apoptotic index (AI) as follows: 0%, 0-1%, and > 1%. A high AI was associated with a decreased local recurrence rate compared with an intermediate or a low AI (P = 0.024). There was no significant relation between AI and survival. There was a significant reduction in the local recurrence rate for irradiated patients compared with the nonirradiated in the low (P = 0.015) and intermediate (P = 0.038) AI groups. In the high AI group, there were few recurrences and no significant difference was observed between irradiated and nonirradiated patients. The relative risk of death from rectal carcinoma in Dukes A-C patients was not significantly decreased by radiotherapy, but, in the intermediate AI group, there was a trend (P = 0.08) in favor of the irradiated patients.CONCLUSION: A high AI in rectal carcinoma indicated a decreased local recurrence rate.
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20.
  • Bergö, Martin, 1970, et al. (författare)
  • Inactivation of Icmt inhibits transformation by oncogenic K-Ras and B-Raf
  • 2004
  • Ingår i: J Clin Invest. ; 113:4, s. 539-550
  • Tidskriftsartikel (refereegranskat)abstract
    • Isoprenylcysteine carboxyl methyltransferase (Icmt) methylates the carboxyl-terminal isoprenylcysteine of CAAX proteins (e.g., Ras and Rho proteins). In the case of the Ras proteins, carboxyl methylation is important for targeting of the proteins to the plasma membrane. We hypothesized that a knockout of Icmt would reduce the ability of cells to be transformed by K-Ras. Fibroblasts harboring a floxed Icmt allele and expressing activated K-Ras (K-Ras-Icmt(flx/flx)) were treated with Cre-adenovirus, producing K-Ras-Icmt(Delta/Delta) fibroblasts. Inactivation of Icmt inhibited cell growth and K-Ras-induced oncogenic transformation, both in soft agar assays and in a nude mice model. The inactivation of Icmt did not affect growth factor-stimulated phosphorylation of Erk1/2 or Akt1. However, levels of RhoA were greatly reduced as a consequence of accelerated protein turnover. In addition, there was a large Ras/Erk1/2-dependent increase in p21(Cip1), which was probably a consequence of the reduced levels of RhoA. Deletion of p21(Cip1) restored the ability of K-Ras-Icmt(Delta/Delta) fibroblasts to grow in soft agar. The effect of inactivating Icmt was not limited to the inhibition of K-Ras-induced transformation: inactivation of Icmt blocked transformation by an oncogenic form of B-Raf (V599E). These studies identify Icmt as a potential target for reducing the growth of K-Ras- and B-Raf-induced malignancies.
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21.
  • Buyanova, Irina, 1960-, et al. (författare)
  • Analysis of band anticrossing in GaNxP1-x alloys
  • 2004
  • Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70, s. 085209-
  • Tidskriftsartikel (refereegranskat)abstract
    •  Temperature-dependent absorption, photoluminescence excitation, and spectroscopic ellipsometry measurements are employed to accurately determine compositional and temperature dependences of the conduction band (CB) states in GaNP alloys. The CB edge and the higher lying Γc CB minimum (CBM) are shown to exhibit an apparently anticrossing behavior, i.e., the N-induced redshift of the bandgap energy is accompanied by a matching blueshift of the Γc CBM. The obtained data can be phenomenologically described by the band anticrossing model. By considering strong temperature dependence of the energy of the interacting N level, which has largely been overlooked in earlier studies of GaNP, the interacting N level can be attributed to the isolated substitutional NP and the coupling parameter is accurately determined.
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23.
  • Buyanova, Irina, 1960-, et al. (författare)
  • Direct experimental evidence for unusual effects of hydrogen on the electronic and vibrational properties of GaNxP1−x alloys : a proof for a general property of dilute nitrides
  • 2004
  • Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 70:24, s. 245215-245219
  • Tidskriftsartikel (refereegranskat)abstract
    • Direct experimental evidence for dramatic effects of hydrogen incorporation on the electronic structure and lattice properties of GaNxP1−x alloys is presented. By employing photoluminescence excitation spectroscopy, postgrowth hydrogenation is shown to reopen the band gap of the GaNP alloys and to efficiently reduce the N-induced coupling between the conduction band states. By Raman spectroscopy, these effects are shown to be accompanied by hydrogen-induced breaking of the Ga-P bond in the alloy, evident from disappearance of the corresponding vibrational mode. According to the performed Raman and x-ray diffraction measurements, the hydrogenation is also found to cause a strong expansion of the GaNP lattice, which changes the sign of strain from tensile in the as-grown GaNP epilayers to compressive in the posthydrogenated structures, due to the formation of complexes between N and H.
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24.
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25.
  • Fang, Hong, et al. (författare)
  • Selection of cefoxitin-resistant Bacteroides thetaiotaomicron mutants and mechanisms involved in beta-lactam resistance
  • 2002
  • Ingår i: Clinical Infectious Diseases. - : Oxford University Press (OUP). - 1058-4838 .- 1537-6591. ; 35, s. S47-S53
  • Tidskriftsartikel (refereegranskat)abstract
    • The beta-lactam antibiotics are the most widely used of all the groups of antimicrobials, but beta-lactam resistance is increasingly common among members of the Bacteroides fragilis group. Three major mechanisms are involved in beta-lactam resistance, and they act together in certain instances. In the present study, 2 resistant mutants (238m and 1186m) of Bacteroides thetaiotaomicron, obtained from clinical isolates (238 and 1186) by selection with increasing concentrations of cefoxitin, showed decreased susceptibilities to cefoxitin and other beta-lactam antibiotics. Alterations in both penicillin-binding proteins (PBPs) and outer-membrane proteins (OMPs) were observed in the mutants in comparison with their parent strains. The similar alteration in OMPs was also observed in clinical isolates. In conclusion, the beta-lactam-resistant mutants of B. thetaiotaomicron with deficiency in both PBPs and OMPs can be selected for by exposure to cefoxitin, and several mechanisms are involved in the beta-lactam resistance in the strains investigated.
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27.
  • Hong, Y., et al. (författare)
  • Film blowing of linear low-density polyethylene blended with a novel hyperbranched polymer processing aid
  • 2000
  • Ingår i: Polymer. - 0032-3861 .- 1873-2291. ; 41:21, s. 7705-7713
  • Tidskriftsartikel (refereegranskat)abstract
    • The use of hyperbranched polymer (HBP) as a processing aid for linear low-density polyethylene (LLDPE) in the tubular film blowing process was investigated. Through the addition of HBP, sharkskin was successfully eliminated without significantly changing the overall physical properties of LLDPE films. Also, there was a minimum of 40% enhancement in processing rate with addition of 0.5 wt% HBP. The study showed that HBP and LLDPE are immiscible, and HBP has a tendency to migrate to the surface, subsequently, it seems to form a lubricating layer between the metal surfaces and the bulk material. This phase separation between HBP and LLDPE results in an HBP-rich surface, which has a high potential to create unique surface properties tailored to various applications. Rheological analysis indicated that excessive slip was present in HBP/LLDPE suggesting that the onset of slip is not the cause of sharkskin. On the contrary, it may be partially responsible for the elimination of sharkskin.
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31.
  • Thinh, N. Q., et al. (författare)
  • Formation of Ga interstitials in (Al,In)yGa1-yNxP1-x alloys and their role in carrier recombination
  • 2004
  • Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85, s. 2827-
  • Tidskriftsartikel (refereegranskat)abstract
    • Formation of complex defects involving a Ga interstitial (Gai) in (Al,In)yGa1-yNxP1-x alloys and their effects on optical quality are studied by photoluminescence (PL) and optically detected magnetic resonance spectroscopies. Introduction of these defects is shown to be largely promoted by incorporation of N. In quaternary alloys, concentrations of the defects are found to critically depend on the group III atoms that replace Ga, i.e., it is largely enhanced by the presence of Al in alloys, but is only marginally affected by In incorporation. The effect is attributed to differences in surface adatom mobilities of the group III atoms involved and their bonding strength with N. The revealed Gai complexes are shown to act as efficient nonradiative recombination centers degrading the PL efficiency. The defects exhibit high thermal stability and can only be partially removed by postgrowth rapid thermal annealing.
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32.
  • Thinh, N. Q., et al. (författare)
  • Identification of Ga-interstitial defects in GaNyP1−y and AlxGa1−xNyP1−y
  • 2004
  • Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : APS. - 1098-0121 .- 1550-235X. ; 70:12, s. 121201-
  • Tidskriftsartikel (refereegranskat)abstract
    • Two Ga -interstitial (Gai) defects are identified by optically detected magnetic resonance as common grown-in defects in molecular beam epitaxial GaNyP1−y and AlxGa1−xNyP1−y. Characteristic hyperfine structure arising from spin interaction between an unpaired electron and a Ga nucleus is clearly resolved. The observed strong and nearly isotropic hyperfine interaction reveals an electron wave function of A1 symmetry that is highly localized at the Gai and thus a deep-level defect. Our analysis based on first-principles calculations suggests that these defects are complexes containing one Gai2+ .
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33.
  • Vorona, Igor, et al. (författare)
  • Identification of Ga interstitials in GaAlNP
  • 2003
  • Ingår i: Proceedings of the 22nd International Conference on Defects in Semiconductors. - : Elsevier BV. ; , s. 466-469
  • Konferensbidrag (refereegranskat)abstract
    • New dilute nitride Ga1-xAlxNyP1-y alloys grown by gas-source molecular beam epitaxy have been studied by the optical detected magnetic resonance technique. Two paramagnetic defect centers with an effective electron spin S = 1/2 were observed and shown to involve Ga interstitials (denoted as Gai-A and Gai-B), both exhibiting the characteristic hyperfine (HF) structure from the two Ga isotopes. The HF interaction is shown to be nearly isotropic and rather strong, providing evidence for an A1 symmetry of the electron wave function highly localized at the Ga atom. We tentatively attribute Gai-A and Gai-B to the interstitial sites surrounded by group-III and group-(V and III) atoms, respectively. © 2003 Elsevier B.V. All rights reserved.
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