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  • 1
    Electronic Resource
    Electronic Resource
    Hydrothermal Synthesis of Nanosize alpha-Al2O3 from Seeded Aluminum Hydroxide (1998)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 81 (1998), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: alpha-Alumina and boehmite particles were synthesized by coprecipitation followed by a hydrothermal treatment. X-ray diffraction (XRD) indicated that alpha-Al2O3 was the major phase and coexisted with 4% of boehmite in the presence of the alpha-Al2O3 seeds. On the other hand, a single boehmite phase was obtained in the absence of the alpha-Al2O3 seed particles. The powder densified in the temperature range from 1050° to 1350°C. High-resolution transmission electron microscopy (HRTEM) showed that the particle size of the synthesized alpha-Al2O3 was 60 nm. The surface area was 245 m2/g.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1998.tb02687.x
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  • 2
    Electronic Resource
    Electronic Resource
    Ultraviolet laser ablation of polymers: spot size, pulse duration, and plume attenuation effects explained (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 5458-5468 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A versatile model for ultraviolet (UV) laser ablation of polymers is presented, which is very successfully applied to the calculation of a variety of different properties of this process, including the influence of plume attenuation dynamics. The polymer is described as a system of chromophores with two possible electronic states. The model is based on the combination of photothermal decomposition and photodissociative bond breaking in the electronically excited state. Laser induced chemical modifications are incorporated via different absorption coefficients for the initial and for the modified polymer after absorption of UV light. Dynamic attenuation of the expanding ablation plume and heat conduction are taken into account. The results of the theoretical calculations are compared with the results of three different series of experiments performed with polyimide (PI) and polymethylmethacrylate at the excimer laser wavelength 248 nm and with PI also at 308 nm: (1) Measurement of the ablation rate as a function of fluence for four different pulse durations between 20 and 250 ns; (2) Measurements of the ablation rate as a function of fluence for five different laser irradiation spot radii between 10 and 150 μm, and (3) Time resolved measurement of the dynamic plume attenuation at the ablating laser wavelength as a function of fluence for four different pulse durations between 20 and 250 ns. The model leads to a prediction of etch rates, ablation thresholds, plume attenuation, and surface temperatures during the ablation process, which is in good agreement with the experimental results. The observed increase of the ablation rate with increasing pulse length and with decreasing laser spot size can be explained by the model as a consequence of laser induced modified absorption in combination with the dynamic shielding of the expanding plume. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367377
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  • 3
    Electronic Resource
    Electronic Resource
    Tunneling-like magnetoresistance in bicrystal La0.8Sr0.2MnO3−δ thin films (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2506-2508 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial ferromagnetic La0.8Sr0.2MnO3−δ films have been sputtered on SrTiO3 bicrystal substrates. Etched patterns crossing the bicrystal grain boundary are compared with identical patterns not crossing it. The films were annealed at different conditions and their magnetoresistance measured as a function of temperature T and of in plane magnetic field H strength and direction. Annealing at 900 °C was found to modify the grain boundary and to increase its magnetoresistance. For H=±80 Oe parallel to the grain boundary and T=32 K narrow magnetoresistance peaks of 60% height are measured. They are interpreted in the frame of an in plane magnetotunneling structure. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122497
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  • 4
    Electronic Resource
    Electronic Resource
    When should prophylactic treatment in patients with haemophilia A and B start?— The German experience (1998)
    Oxford, UK : Blackwell Science Ltd
    Haemophilia 4 (1998), S. 0 
    Details
    ISSN: 1365-2516
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. Radiological and orthopaedic outcome in severe and moderate haemophilia A and B patients undergoing long-term prophylactic treatment were prospectively investigated focusing on the age of onset of prophylaxis and the number of joint bleedings prior to treatment. We report on 21 patients with severe and moderate haemophilia A and B receiving prophylactic treatment of between 3.1 and 16.1 year's duration. Three patient groups were evaluated according to the age at onset of prophylaxis. In group I prophylactic treatment was initiated in the first 2 years of life. Patients in group II received prophylaxis at the age of 3–6 years. Late-onset or secondary prophylactic treatment was started at the age of 6 years and above in seven patients (group III). All patients received virus-inactivated F VIII or F IX concentrates at dosages of 30–50 IU/kg body weight i.v. three times per week for those with haemophilia A and twice per week for those with haemophilia B. Elbow, knee and ankle joints were investigated at 3–4-yearly intervals according to the radiological and orthopaedic scores recommended by the World Federation of Haemophilia. The total number of joint bleedings before and after start of prophylaxis were recorded in all patients. In group I 7/8 patients had unaffected joints with constant radiological and orthopaedic scores of zero or 1, after a median of 11.25 years of prophylactic treatment. One patient in this group demonstrated mild radiological alterations (score 4). Patients in group II showed neither radiological nor orthopaedic alterations at study entry. Surprisingly, worsening joint scores could be detected despite ongoing prophylaxis after the 3-year interval (median orthopaedic score 4, median radiological score 8). Treatment group III already showed considerable joint damage at study entry with a median radiological score of 11 (0–33) and a median orthopaedic score of 4 (0–11). Despite prophylactic treatment, both radiological (median 19.5, range 2–47) and orthopaedic scores (median 8, range 2–12) deteriorated after 3 years. Prior to onset of prophylaxis, no or only one joint bleeding occurred in treatment group I. In group II, a median of six joint bleeds (range 1–8) was reported before prophylaxis was started. Patients in group III usually experienced a median of more than 10 joint haemorrhages (range 6–10 or more). Under prophylactic treatment the number of joint bleedings decreased significantly in group II and III. However, radiological and orthopaedic scores increased as a sign of progressing osteoarthropathic alterations in patients reporting more than five joint haemorrhages before onset of prophylaxis whereas no joint alterations could be assessed in patients with no or only one joint bleeding episode prior to prophylaxis. Even a small number of joint bleedings seems to cause irreversible osteoarthropathic alterations leading to haemophilic arthropathy. Once apparent, further progression of joint damage could not be arrested despite of prophylactic treatment (groups II and III). In order to prevent haemophilic arthropathy, effective prophylaxis should be started before or at least after the first joint bleeding in severe haemophilia A and B.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2516.1998.440413.x
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  • 5
    Electronic Resource
    Electronic Resource
    Dichloro(tetrahydrofuran-O)[tris(1-pyrazolyl-N2)borato]vanadium(III) (1998)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 1590-1592 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S010827019800612X
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  • 6
    Electronic Resource
    Electronic Resource
    Primary Extinction and Absorption: a Theoretical Approach Based on the Takagi-Taupin Equations. Application to Spherical Crystals (1998)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 191-198 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The primary-extinction problem for X-ray diffraction by perfect crystals is treated using the Becker–Coppens iterative procedure within the Takagi–Taupin equations. An analytical approximation for the primary-extinction factor yp describing both the effects of the X-ray multiple scattering and the absorption processes within the perfect crystal of an arbitrary shape is derived. The solution differs from the known expressions given by Zachariasen and Becker & Coppens on the basis of the Hamilton–Darwin intensity transfer equations and in the limiting case of a non-absorbing crystal it concurs with the Kato–Becker formula found in the Laue approximation of the dynamical theory. The theoretical results are consistent with experimental data of a number of reflections of Ge and Si single-crystal spheres measured at X-ray wavelengths λ = 0.56, 0.71 and 1.54 Å with a laboratory CAD-4 and a Huber four-circle diffractometer at HASYLAB, DESY, Hamburg, Germany. Two novel features are discussed. First, it is shown that by neglecting the X-ray absorption effect the calculated extinction factor yp is close to the value given by the Becker–Coppens formula. Second, it was found that for absorbing spherical crystals with μR ≥ 1 absorption effects cannot be treated separately from the primary-extinction phenomenon because of imaginary dispersion corrections to the atomic form factors. The experimental data are fitted to the Becker–Coppens and present theoretical models. The best fits are found to relate to the present model and produce relatively low R factors of 3 to 6% for the Bragg intensities measured in the cases of Si and Ge spherical crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767397012579
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  • 7
    Electronic Resource
    Electronic Resource
    Differential sensitivity of macrophages to bradykinin (1998)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 357 (1998), S. 151-158 
    Details
    ISSN: 1432-1912
    Keywords: Key words Bradykinin ; Arachidonic acid ; Prostaglandin E2 (PGE2) ; Superoxide radical ; Intracellular Calcium ; NADPH-oxidase ; Guinea pig macrophages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: 2 receptor subtype. However, the receptor activity measured by bradykinin-induced increase in intracellular free calcium [Ca2+]i was very low compared to elicited peritoneal macrophages. These findings indicate that the stage of differentiation/maturation and activation of macrophages may be important for the ability of bradykinin to stimulate these cells to inflammatory responses in vivo.
    Notes: Abstract In this report, we investigated the responsiveness of subpopulations of elicited peritoneal macrophages between each other compared to resident tissue macrophages of alveoli of guinea pig to the action of bradykinin. Bradykinin stimulated the secretion of superoxide radical, arachidonic acid and prostaglandin E2 (PGE2) via the bradykinin B2 receptor subtype in peritoneal macrophages, indicated by complete inhibitory effect of the bradykinin B2 receptor antagonist HOE 140. The extent of the secretion, however, varied substantially between macrophages of different size. The highest level of the secretion was observed in the fraction containing the intermediate-size macrophages, while progressively lower level of the secretion was observed with decreasing size. In contrast, large macrophages obviously lost their secretory ability. Additionally, the bradykinin-stimulated release of cyclooxygenase products exerted an inhibitory action on NADPH-oxidase activity depending on size and stage of maturation/activation of macrophages, as judged by an increase in superoxide radical generation by indomethacin (100 μM) preincubation of cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005149
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  • 8
    Electronic Resource
    Electronic Resource
    Tracheobronchoskopie und Ösophagoskopie in der Hals-Nasen-Ohren-Heilkunde Eine Standortbestimmung* (1998)
    Springer
    HNO 46 (1998), S. 643-650 
    Details
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Tracheobronchoskopie ; Ösophagoskopie ; HNO ; Komplikationen ; Key words Tracheobronchoscopy ; Esophagoscopy ; Surgical complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary It is the task of each medical specialty to develop guidelines for diagnosis and therapies. Examinations done by several specialties should follow a common consensus. A randomized survey at 70 German ENT departments investigated the current position of tracheobronchoscopy and esophagoscopy at each institution. Sixty questionnaires were evaluable. Altogether 8,295 tracheobronchoscopies and 10,404 esophagoscopies were performed. Thirty-six percent of all tracheobronchoscopies and 6% of all esophagoscopies were done with a flexible system. Approximately 58% of all tracheobronchoscopies and 55% of all esophagoscopies were performed for tumor staging. Complications during tracheobronchoscopy occurred in 0.8% of cases and in 0.58% of the esophagoscopies. Using these data an interdisciplinary quality assurance concept was developed for tracheobronchoscopy and esophagoscopy. Current experience has shown that a otolaryngologists in Germany mainly perform rigid tracheobronchoscopy and esophagoscopy. Although endoscopy is mostly done in cases with varied anatomic structures, complications are very rare and comparable to flexible techniques. Greater experience with flexible systems also is to be encouraged in ENT departments.
    Notes: Zusammenfassung Hintergrund: Es muß Aufgabe jedes einzelnen Fachbereichs sein, Leitlinien für die von ihm behandelten Erkrankungen und durchgeführten Untersuchungen zu erstellen. Für fachübergreifende Behandlungen ergibt sich die Forderung nach einem gemeinsamen Konsens. Material und Methoden: Durch eine anonymisierte Umfrage an 70 HNO-Kliniken und Belegabteilungen sollte ein Ist-Stand der Tracheobronchoskopie und Ösophagoskopie in der Hals-Nasen-Ohren-Heilkunde erhoben werden. Ausgewertet werden konnten insgesamt 60 Fragebögen. Unter Berücksichtigung dieser Ergebnisse wurde ein Leitlinienentwurf „Tracheobronchoskopie und Ösophagoskopie” erarbeitet. Ergebnisse: Insgesamt wurden 8295 Tracheobronchoskopien und 10404 Ösophagoskopien durchgeführt; 36% der Tracheobronchoskopien und 6% der Ösophagoskopien erfolgten mit einem flexiblen System. In 58% der Fälle erfolgte die Tracheobronchoskopie zum Tumorstaging, bei der Ösophagoskopie betrug die Anzahl der Untersuchungen zum Tumorstaging 55%. Die Komplikationsrate bei der Tracheobronchoskopie betrug 0,8%, bei der Ösophagoskopie 0,58%. Aufbauend auf diesen Strukturdaten wurde ein interdisziplinär erarbeiteter Leitlinienentwurf in einem Delphiverfahren abgeglichen. Schlußfolgerungen: Die Hals-Nasen-Ohren-Ärzte in Deutschland führen mehrheitlich die starre Tracheobronchoskopie und Ösophagoskopie durch. Obwohl größtenteils bei veränderten anatomischen Strukturen endoskopiert wird, geschieht dies mit Komplikationsraten, die vergleichbar sind mit internationalen Studien bei Einsatz flexibler Systeme. Trotzdem sollte sich der HNO-Arzt vermehrt auch um die flexiblen Techniken bemühen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001060050289
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  • 9
    Electronic Resource
    Electronic Resource
    Allgemeinanästhesie in der Schwangerschaft (1998)
    Springer
    Der Gynäkologe 31 (1998), S. 910-921 
    Details
    ISSN: 1433-0393
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zwischen 0,5–1,6% der Schwangeren werden jedes Jahr einem nichtgynäkologischen operativen Eingriff unterzogen. Diese Eingriffe stellen für den Anästhesisten eine besondere Herausforderung dar, da er nicht nur die Verantwortung für die Mutter, sondern auch für das ungeborene Leben trägt. Grundsätzlich sind Regionalanästhesieverfahren in der Schwangerschaft zu bevorzugen; je nach operativem Eingriff ist jedoch die Durchführung einer Allgemeinanästhesie unumgänglich. Die Durchführung einer Allgemeinanästhesie bei Schwangeren erfordert ein profundes Wissen der physiologischen mütterlichen Veränderungen, des Einflusses der gängigen Anästhesieverfahren inklusive der pharmakologischen Substanzen auf das perioperative fetale und mütterliche Outcome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00003090
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  • 10
    Electronic Resource
    Electronic Resource
    Flexible Endoskopie im HNO-Bereich (1998)
    Springer
    HNO 46 (1998), S. 654-659 
    Details
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Flexible Endoskopie ; Ösophagoskopie ; Tracheobronchoskopie ; Laryngoskopie ; Key words Flexible endoscopy ; Esophagoscopy ; Tracheobronchoscopy ; Laryngoscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Although rigid esophagoscopy and tracheobronchoscopy have always been a domain of the ENT surgeon, the development of flexible endoscopes has increased diagnostic and therapeutic indications in clinical practice. Component elements of fiberendoscopes and CCD endoscopes are shown. Techniques in flexible bronchoscopy, flexible esophagoscopy and rhinolaryngoscopy are explained. General and special indications of fiberendoscopy are listed. Possibilities and limitations of flexible bronchoscopy are shown. Flexible techniques for removing foreign bodies of the esophagus and indications for mini-endoscopy are demonstrated. Experience has shown that flexible endoscopy has brought the diagnosis and therapy of tubular organs into a new perspective. Since flexible techniques do not replace rigid ones and complement each another, ENT surgeons must be trained in both techniques.
    Notes: Zusammenfassung Hintergrund: Die Endoskopie von Ösophagus und Tracheobronchialbaum war als starre Technik stets eine Domäne des HNO-Arztes. Mit der Entwicklung der flexiblen Endoskope haben sich die diagnostischen und therapeutischen Anwendungsmöglichkeiten erweitert. Material und Methoden: Dargestellt werden der technische Aufbau der Fieberglasendoskope und der CCD-Endoskope. Der Untersuchungsablauf der Bronchoskopie, der Ösophagoskopie und der Rhinolaryngoskopie werden erläutert. Ergebnisse: Allgemeine und spezielle Indikationen der Fiberendoskope werden aufgeführt, außerdem werden die Möglichkeiten und Grenzen der flexiblen Bronchoskopie diskutiert. Techniken der flexiblen Ösophagusfremdkörperentfernung und Anwendungsbeispiele für Miniendoskope werden erläutert. Schlußfolgerung: Die flexible Endoskopie hat die Diagnostik und Therapie von Hohlorganen in eine neue Dimension gebracht und ihr zu einer weiten Verbreitung verholfen. Flexible Verfahren ersetzen nicht die Starren, sondern sie ergänzen sich gegenseitig und das Repertoire eines HNO-Arztes sollte sich auf beide Techniken erstrecken.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001060050290
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