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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 3597-3601 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results of a combined experimental and theoretical study are presented. GaAs{113} and {112} surfaces have been prepared by molecular beam epitaxy and analyzed in situ by low-energy electron diffraction and ex situ by atomic-force microscopy. The experimentally found structures are in full agreement with surface energies calculated by density-functional theory. The {112} surfaces are unstable under faceting into low-index planes, whereas the {113} surfaces appear as singular surfaces. Particularly, for GaAs(113) the surface energy is comparable with the values for the low-index surfaces. The impacts of these results on the interface between InAs quantum dots and the embedding GaAs matrix are discussed. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Pediatric anesthesia 7 (1997), S. 0 
    ISSN: 1460-9592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Midazolam was applied transmucosally in 47 children randomly assigned to three different groups. Group N received 0.2 mg·kg−1 nasally, group R 0.5 mg·kg−1 rectally, and group S 0.2 mg·kg−1 sublingually. All groups were treated 60 min prior to a planned i.v. puncture with EMLA®. Reliable and valid psychological parameters (such as emotional situation, shivering, awareness, respiratory rate and facial colour) were scored after premedication and before and after i.v. puncture, 20 min after premedication and until induction. A blood sample was drawn 10, 30 and 60 min after premedication and the levels of midazolam, alpha-hydroxy-midazolam, ACTH, glucose and cortisol were measured. In all three groups the plasma levels of midazolam 10 min after premedication were higher than 70 ng·ml−1 (accepted as a sedative level). 30 min after premedication the midazolam level in the sublingual group was statistically significantly higher than in the nasal group and the psychological parameters in all three groups were significantly changed (10 min after premedication). The psychological parameters were not significantly different between the three groups over the whole study. Sublingual premedication has some advantages (most readily accepted, highest plasma levels and lowest deviations) and could be the first choice in premedication of children. All three transmucosal applications are safe and well accepted, although nasal application was rejected by two of the children.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 1432-1439 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In order to investigate microscopic steps of ammonia synthesis on Ru surfaces, hydrogen adsorption on a Ru(0001) surface, precovered by atomic nitrogen, has been studied using high-resolution electron energy loss spectroscopy (HREELS) and thermal desorption spectroscopy (TDS). Hydrogen adsorption has been performed with the Ru sample at 90 and 300 K. At 90 K, the saturation coverage of hydrogen decreases with increasing N precoverage. The vibrational properties of H do not change much in the presence of N compared to those on the bare Ru(0001) surface exhibiting one single mode at 85 meV for small H coverages and losses at 99 and 141 meV at H saturation. Heating of the H+N coadsorbed layer from 90 to 300 K does not result in any observable N–H bond formation. After exposure of N/Ru(0001) to H2 at room temperature, however, NH3 and NH species are observed on the surface. NH3 is characterized by its symmetric bending mode δs at 145 meV. The reaction intermediate NH is stable up to 400 K and shows losses of ν(Ru-NH), δ(N–H), and ν(N–H) at 86, 166, and 410 meV, respectively. A barrier height of 93 kJ/mol is estimated for the NH3 synthesis reaction from N and H. In the presence of some coadsorbed Cs, NHx species are not observed at 300 K indicating a destabilization of NHx by Cs. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 375-381 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dissociative chemisorption of N2 on Ru(0001), Ru(101¯0), and Ru(112¯1) surfaces at 300 K was studied by means of high-resolution electron energy loss spectroscopy and thermal desorption spectroscopy. The initial sticking coefficient was determined to s0=(1±0.8)×10−12, within the limits of error independent of surface orientation. On Ru(101¯0) and Ru(112¯1) small amounts of N can be dissolved into the subsurface region. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 8944-8950 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The N/Ru(0001) system was studied by thermal desorption spectroscopy (TDS), low-energy electron diffraction (LEED), and high-resolution electron energy-loss spectroscopy (HREELS). Atomic nitrogen was prepared by NH3 decomposition at sample temperatures decreasing from 500 to 350 K during NH3 exposure. A maximum N coverage of θN=0.38 could thus be achieved. (square root of 3), split 2×2 and 2×2 LEED patterns were observed for decreasing θN. After NH3 decomposition and before annealing the sample to a temperature above 400 K, the surface is composed of adsorbed N, H, and NH species. This composite layer exhibits a split (square root of 3) LEED pattern due to domains of size 4 with heavy walls. This phase decays through dissociation of NH leading to sharp first-order type desorption peaks of H2 and N2. From the weak intensity of the ν(Ru–NH) stretch mode it is concluded that NH is adsorbed at threefold-hollow sites. The energy of the ν(Ru–N) mode shifts from 70.5 to 75.5 meV when θN is increased from 0.25 to 0.38. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 11147-11154 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: OH species adsorbed on Pt(111) were studied in a combined investigation using scanning tunneling microscopy (STM) and high-resolution electron energy loss spectroscopy (HREELS). OH was formed by two different reactions, by reaction of H2O with O, and as an intermediate in the reaction of O with hydrogen to H2O. In both cases, two ordered OH phases were observed, a ((square root of)3×(square root of)3)R30° and a (3×3) structure, for which models are proposed. Both structures have OH coverages of 2/3, and their formation is driven by hydrogen bond formation between the adparticles; the OH adsorption site is most likely on top. OH molecules at defects in the adlayer, in particular at island edges, are spectroscopically distinguishable and contribute significantly to the vibrational spectra in disordered OH layers. This is important for the water formation reaction, where the OH islands are small. The discrepancies between previous HREELS studies on OH can be explained by the different degree of order under the various formation conditions. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 9313-9319 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dissociative chemisorption of nitrogen on the Ru(101¯0) surface has been studied using high-resolution electron energy loss spectroscopy (HREELS), thermal desorption spectroscopy (TDS) and low-energy electron diffraction (LEED). To prepare a surface covered by atomic nitrogen we have used ionization-gauge assisted adsorption. A saturation coverage of θN=0.6 is achieved of which about 30% is in the subsurface region. At saturation coverage a ( 2 1−1 1) LEED pattern is observed. The ν(parallel)(Ru–N) mode at 41 meV and the ν⊥(Ru–N) mode at 60 meV are identified. Upon exposing the nitrogen covered surface to hydrogen at 300 K we have observed the formation of NH3 which is characterized by its symmetric bending mode δs(NH3) at 149 meV. At 400 K, NH3 could not be detected. The reaction intermediate NH is stable up to 450 K and has been identified by its vibrational losses ν(Ru–NH) at 86 meV, and ν(N–H) at 408 meV. The TD spectra of mass 14 show three desorption states of nitrogen, Nα at 740 K (from subsurface N), Nβ shifting from 690 to 640 K with increasing coverage, and Nγ at 550 K. The activation energy for desorption via the Nβ state is 120±10 kJ/mol. The TD spectra of mass two showed three desorption states at 450, 550, and 650 K due to the decomposition of NHx. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 10231-10238 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photodesorption of oxygen admolecules was studied on a stepped Pt(113)=(s)2(111)×(001) surface with 193 nm irradiation at 110 K. Multidirectional desorptions were found to collimate at ±12–20° and ±45–49° off the surface normal and also along the surface normal in a plane along the trough. The first component is always dominant, and the weak second component only appears at higher oxygen coverages. The normally directed desorption is not significant. The translational energy of desorbing O2 peaks around 15–20° and 50°, confirming the inclined desorptions. It is proposed that these inclined components are due to the desorption induced by the impact of oxygen admolecules with hot oxygen atoms from the photodissociation of adsorbed molecular oxygen, emitted along the trough. A simple cosine distribution was found to fit the thermal desorption from oxygen admolecules and also the recombinative desorption of oxygen adatoms. The 193 nm irradiation also produces additional, less tightly bound oxygen adatoms, which yield a desorption component collimated at 15° from the surface normal in the step-down direction. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 3417-3422 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The interaction of Cs and CO was studied for submonolayer coverages of Cs on Ru(0001) by means of high-resolution electron energy-loss spectroscopy (HREELS), thermal desorption spectroscopy (TDS), and low-energy electron diffraction (LEED). From the HREEL spectra and the 2×2 LEED pattern it is concluded that two-dimensional islands of Cs+2CO stoichiometry are formed first. For high CO doses CO adsorbs on the bare Ru surface between the islands as concluded from the ν(C–O) stretch-mode frequency and the ((square root of 3)×(square root of 3))R30° LEED pattern. Besides some local interaction between CO and Cs, there is strong evidence found for a long range, through substrate interaction. Our data can be understood in terms of a charge redistribution model; Cs donates a given amount of charge to the surface which is then backdonated to and shared between the adsorbed CO molecules within the (Cs+2CO)-islands and outside of them on the bare surface. The desorption temperature of CO with θCO→0 increases nearly linearly with θCs indicating CO desorption out of a two dimensional Cs gas in which the lateral interaction increases with θCs. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Cell-Saver ; intraoperative Autotransfusion ; radikale Prostatektomie ; Tumorzellen ; Urinkontamination ; Key words Cell saver ; Intraoperative autotransfusion ; Tumour cells ; Urine contamination ; Radical prostatectomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Intraoperative autotransfusion (MAT), preoperative autologous blood donation, and preoperative normovolaemic haemodilution are three different methods to avoid homologous blood transfusion during surgical procedures. The controversial use of MAT via cell saver in tumour surgery as well as contamination of the operative field with urine illustrate the particular difficulties of autologous blood transfusion in connection with radical prostatectomy. We investigated changes in the osmotic resistance of the retransfused red blood cells (RBC), bacterial contamination, changes in coagulation parameters, and the presence of tumour cells. Patients and methods: After written informed consent, 24 patients who presented for radical prostatectomy were randomly allocated to either a group that used MAT or a group that used homologous transfusion. The patients received „balanced anaesthesia” with midazolam, fentanyl, atracurium, and nitrous oxide/oxygen. The analysed parameters from the preoperative period to the 3rd postoperative day are shown in Table 1. The Haemonetics 3 Plus Cell Saver was used for autotransfusion. Results: Our results showed that the haematologic parameters, coagulation factors, and serum chemistry did not differ between the two groups (Tables 2–4). However, there were significant differences during the investigated period. The osmotic resistance of the salvaged RBCs was higher than that preoperatively. Furthermore, there were no tumour cells in the autologous salvaged RBCs. Conclusion: Our results showed no decrease in the quality of the autotransfused RBCs, urine was not retransfused; and there were no significant differences between the groups postoperatively. Although there were no tumour cells in the salvaged blood, the possibility of blood irradiation is discussed. We concluded that because of the risk of infection of homologous blood products, MAT is a safe possibility to reduce the amount of homologous blood transfusion required in connection with radical prostatectomy.
    Notes: Zusammenfassung Mit der intraoperativen maschinellen Autotransfusion (MAT) steht heute, neben anderen Möglichkeiten wie der präoperativen Eigenblutspende und der präoperativen normovolämischen Hämodilution, ein Verfahren zur Vermeidung von Fremdbluttransfusion zur Verfügung. Der Einsatz der MAT in der Tumorchirurgie sowie die Urinkontamination des OP-Situs zeigen die besonder Problematik der Qualitätssicherung des autologen Blutersatzes bei radikalen Prostatektomien. Neben möglichen Qualitätsveränderungen der retransfundierten Erythrozyten galt es, die Infektionsgefährdung, Gerinnungsveränderungen und eine mögliche Retransfusion von Tumorzellen zu untersuchen. Die Untersuchung wurde an insgesamt 24 Patienten der Urologischen Universitätsklinik Erlangen im Rahmen einer prospektiv randomisierten Studie durchgeführt. Anhand der Ergebnisse fand sich keine Qualitätsminderung der autotransfundierten Erythrozyten, Urin wurde nicht retransfundiert, und im postoperativen Verlauf konnten keine signifikanten Unterschiede zwischen den Vergleichsgruppen nachgewiesen werden. Tumorzellen im Cell-Saver-Erythrozytenkonzentrat (CS-EK) fanden sich nicht, eine Bestrahlung der CS-EK wird diskutiert. Gerade vor dem Hintergrund des bestehenden Infektionsrisikos homologer Blutprodukte sollte die MAT bei radikalen Prostatektomien als Möglichkeit zur Reduktion des Fremdblutbedarfs genutzt werden.
    Type of Medium: Electronic Resource
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