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  • 1
    Electronic Resource
    Electronic Resource
    Room temperature study of low temperature grown Al0.3Ga0.7As/GaAs multiple quantum wells by modulation reflectance (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 8589-8593 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We studied the subband energy levels in AlGaAs/GaAs multiple quantum wells grown at different temperatures (200–600 °C) by using the piezoreflectance and photoreflectance in room temperature. Under subsequent 30 s rapid-thermal annealing at different temperatures (600–1000 °C), we observed a large energy blueshift in samples with growth temperature below 400 °C. This blueshift energy may be attributed to the modification of quantum wells caused by gallium vacancy enhanced Al–Ga interdiffusion. The energy blueshifts were analyzed by solving Fick's second law for Al diffusion in quantum wells, obtaining an effective activation energy of 0.75 eV. We discuss our results using the nonequilibrium diffusion equation and comparing them with other experiments. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373583
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  • 2
    Electronic Resource
    Electronic Resource
    Highly bright blue organic light-emitting devices using spirobifluorene-cored conjugated compounds (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 577-579 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An efficient and morphologically stable pyrimidine-containing spirobifluorene-cored oligoaryl, 2,7-bis[2-(4-tert-butylphenyl)pyrimidine-5-yl]-9,9′-spirobifluorene (TBPSF), as an emitter or a host for blue organic light-emitting devices (OLEDs), is reported. The steric hindrance inherent with the molecular structure renders the material a record-high neat-film photoluminescence (PL) quantum yield of 80% as a pure blue emitter (PL peak at 430 nm) of low molecular weight, and a very high glass-transition temperature (Tg) of 195 °C. Blue OLEDs employing this compound as the emitter or the emitting host exhibit unusual endurance for high currents over 5000 mA/cm2. When TBPSF is used as a host for perylene in a blue OLED, maximal brightness of ∼80 000 cd/m2 had been achieved, representing the highest values reported for blue OLEDs under dc driving. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1493669
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  • 3
    Electronic Resource
    Electronic Resource
    Programmable organic light-emitting devices (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3023-3025 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this letter, we report a promising type of electrically programmable, i.e., reconfigurable, organic light-emitting devices (OLEDs) incorporating a thin carrier-blocking layer as the sacrificial fusing layer. In such devices, the carrier-blocking layer has a lower glass transition temperature than neighboring layers. By raising the internal temperature of the device above the transition temperature of the carrier-blocking layer with a large enough current, interdiffusion between organic layers could occur through such a layer. As a consequence, neighboring layers are fused and a new path for carrier transport is formed, bypassing the carrier-blocking property and altering the device characteristics. A device that emits blue light as fabricated but can be transformed into a green-emitting one is demonstrated. Such a type of device may be used for color pixels in OLED displays, user-programmable OLED applications, and nonvolatile memory devices.© 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1414305
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  • 4
    Electronic Resource
    Electronic Resource
    Behaviors of an excess proton in solute-containing water clusters: A case study of H+(CH3OH)(H2O)1–6 (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 176-188 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Behaviors of an excess proton in solute-containing water clusters were investigated using infrared spectroscopy and ab initio calculations. This investigation characterized the structures of protonated methanol-water clusters, H+(CH3OH)(H2O)n with n=2–6, according to their nonhydrogen-bonded and hydrogen-bonded OH stretches in the frequency range of 2700–3900 cm−1. Ab initio calculations indicated that the excess proton in these clusters can be either localized at a site closer to methanol, forming a methyloxonium ion core (CH3OH2+), or at a site closer to water, forming a hydronium ion core (H3O+). Infrared spectroscopic measurements verified the calculations and provided compelling evidence for the coexistence of two distinct structural isomers, CH3OH2+(H2O)3 and H3O+(CH3OH)(H2O)2, in a supersonic expansion. The spectral signatures of them (either CH3OH2+ or H3O+ centered) are the free-OH stretching absorption band at 3706 cm−1 of a single-acceptor-single-donor H2O, and the band at 3673 cm−1 of a single-acceptor CH3OH. At n=4–6, the clusters adopt structures similar to their pure water analogs with five-membered rings starting to form at n=5. The position of the excess proton in them varies sensitively with the number of solvent water molecules as well as the geometry of the clusters. To further elucidate the behaviors of the excess proton in these clusters, we analyze in detail the potential energy surface along the proton transfer coordinate for two specific isomers of n=2 and 4: MW2II and MW4I. It is found that the proton can be nearly equally shared by methanol and the water dimer subunit in the form of CH3OH–H+–(H2O)2, as substantiated by hydrogen bond cooperativity and zero-point vibrational effects. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480653
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  • 5
    Electronic Resource
    Electronic Resource
    The size of interstellar nanodiamonds revealed by infrared spectra of CH on synthetic diamond nanocrystal surfaces (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 1211-1214 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Infrared spectra of CH stretches have been investigated on the surfaces of synthetic diamond crystallites (5, 100, and 700 nm in diameter) to provide insights into the mid-infrared emission bands of stardusts in interstellar media. While the spectrum of 5-nm diamonds fails to display the distinct 2835 cm−1 (or 3.53 μm) band, a remarkably good match of the absorption bands of larger diamond grains with the emission observed for the stars Elias 1 and HD 97048 is obtained. Suggested by this study, the nanodiamonds that can display such characteristic emission bands at 3.53 μm in these two interstellar systems have a size significantly larger than 5 nm. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1434947
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  • 6
    Electronic Resource
    Electronic Resource
    Comparative ultrastructural studies of the zona radiata of marine fish eggs in three genera in Perciformes (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 56 (2000), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The eggs of Mugil cephalus were significantly larger than those of Epinephelus malabaricus, and E. coioides, while those of Sciaenops ocellatus were intermediate between E. coioides and M. cephalus. The distribution density of pores in the egg envelope of S. ocellatus was significantly different from that of E. malabaricus and E. coioides. The micropyle diameters were significantly different in the four species. The ultrastructure of the zona radiata surface, the distribution density of pores and the size of eggs were also useful characters for distinguishing among the four species, but the ultrastructural features of the micropyles were the most important of all for egg identification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2000.tb00759.x
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  • 7
    Electronic Resource
    Electronic Resource
    Premedication with dextromethorphan provides posthemorrhoidectomy pain relief (2000)
    Springer
    Diseases of the colon & rectum 43 (2000), S. 507-510 
    Details
    ISSN: 1530-0358
    Keywords: Dextromethorphan ; Hemorrhoidectomy ; NMDA receptor ; Preemptive analgesia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: Previous studies have shown that N-methyl-D-aspartate receptor antagonists provide a preemptive analgesic effect in humans. This study was designed to examine whether premedication with dextromethorphan, an N-methyl-D-aspartate antagonist, also provided a preemptive analgesic effect that improved postoperative pain management. METHODS: Sixty patients who were American Society of Anesthesiologists status I and II scheduled for hemorrhoidectomy (modified Whitehead procedure) were included in the study. Patients were randomly assigned to the control and study groups. For the control group patients received chlorpheniramine maleate (20 mg), a component of the injection form of dextromethorphan, intramuscular injection 30 minutes before skin incision. In the study group dextromethorphan 40 mg containing 20 mg chlorpheniramine maleate (intramuscular) was given as premedication 30 minutes before skin incision. Pethidine (1 mg/kg, intramuscular) was given for pain relief as required postoperatively. The time to first pethidine injection, total pethidine consumption, worst pain score, and pethidine-related side effects were recorded for 48 hours postoperatively. RESULTS: The times to first pethidine injection (mean ± standard error of the mean) were 5.2±3 and 19.6±6 hours in the control and study groups, respectively. Total pethidine consumption was 140±11.3 and 63.5±11.8 mg in the control and study groups. The worst visual analog scale pain scores were 7.4±0.2 and 5.6±0.3 in the control and study groups during the two-day observation. The numbers of patients who required pethidine injection were 29 and 20 in the control and study groups, respectively. Two patients suffered pethidine-related side effects, such as nausea, vomiting, dizziness, and headache, in the control group, and no patient complained of any side effect in the study group. CONCLUSION: We found that dextromethorphan premedication provided a preemptive analgesic effect, thus producing reduced postoperative pain and pethidine requirement and improved recovery from hemorrhoidectomy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02237195
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  • 8
    Electronic Resource
    Electronic Resource
    Tibial shaft malunion treated with reamed intramedullary nailing: a revised technique (2000)
    Springer
    Archives of orthopaedic and trauma surgery 120 (2000), S. 152-156 
    Details
    ISSN: 1434-3916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Thirty-seven consecutive adult tibial shaft malunions which had not undergone surgical treatment were prospectively treated with reamed intramedullary nailing. Indications for this treatment modality included a malunion of a tibial shaft which had only been conservatively treated, lesion level fitting for traditional or locked reamed intramedullary nail fixation, less than 2 cm shortening, and without evidence of deep infection at present. The malunions were treated with fibulotomy, closed wedge tibial osteotomy, open reaming of the marrow cavity, stable reamed intramedullary nail stabilization with or without supplementation, and cancellous bone grafting. Thirty-four (92%) patients were followed up for at least 1 year (range 1.0–4.3 years), and all achieved a solid union. The union period was 5.8±0.8 months. Complications included 2 (6%) patients with deep infection and 1 (3%) with cortical perforation. However, all 3 patients recovered completely after adequate management. In conclusion, a reamed intramedullary nail is an ideal instrument for tibial shaft malunions in indicated cases. Good exposure of the bony segments to ream the marrow cavity precisely can avoid cortical perforation. Gentle dissection of the soft tissues may lower the infection rate. Concomitant cancellous bone grafting can improve the union rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004020050033
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  • 9
    Electronic Resource
    Electronic Resource
    Esophageal varices in congenital heart disease with total anomalous pulmonary venous connection (2000)
    Springer
    The international journal of cardiovascular imaging 16 (2000), S. 405-409 
    Details
    ISSN: 1573-0743
    Keywords: asplenia syndrome ; computed tomography ; congenital heart disease ; esophageal varices ; total anomalous pulmonary venous connection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Total anomalous pulmonary venous connection (TAPVC) is an uncommon congenital anomaly in which the anatomical presentations vary widely among patients. We hereby present two newborns with TAPVC associated with asplenia syndrome; both had severe esophageal varices due to infradiaphragmatic pulmonary venous drainage. Ultrafast computed tomography (CT) scanning was superior to color Doppler echocardiography and cardiac catheterization as it provided a detailed portrait of the pulmonary drainage. The remarkable radiographic manifestations are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026578412327
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