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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 403 (Dec. 2008), p. 77-80 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A combination of first-principle and thermochemical calculations is applied to compute the phase diagrams of rhenium-nitrogen and of ruthenium-nitrogen at elevated temperature and high pressure. We augment total energy calculations with our approach to treat the nitrogen fugacity at high pressures. We predict a sequential nitridation of Re at high-pressure/high-temperature conditions. At 3000 K, ReN will form from Re and nitrogen at about 32 GPa. A ReN2 with CoSb2-type structure may be achieved at pressures exceeding 50 GPa at this temperature. Marcasite-type RuN2 will be attainable at 3000 K at pressures above 30 GPa by reacting Ru with nitrogen
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 403 (Dec. 2008), p. 147-148 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The ultra-high pressure and temperature synthesis of spinel silicon nitride and germanium nitride on the one hand as well as the successful synthesis of tin nitride at ambient pressure on the other hand have caused an enormous impact on both basic science and technological development of advanced nitrides. Aim and scope of the research in this field is to synthesize novel nitrides for structural and functional applications. High presssure nitrides may combine ultra-high hardness with high thermal stability in terms of decomposition in different environments and are expected to show interesting optoelectronic properties. Here, the state of the art and the progress in the field of novel advanced nitrides and related materials synthesized reproducibly under high pressure are reviewed
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Silicon nitride (Si3N4) is used in a variety of important technological applications. The high fracture toughness, hardness and wear resistance of Si3N4-based ceramics are exploited in cutting tools and anti-friction bearings; in electronic ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Graefe's archive for clinical and experimental ophthalmology 215 (1981), S. 187-191 
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Anhand von mikrobiologischen Untersuchungen wird die Keimfreiheit des handelsüblich gelieferten Gases Schwefelhexafluorid (SF6) bewiesen. Ferner wird festgestellt, daß SF6 unter in vitro-Versuchsbedingungen keine antibakteriellen Aktivitäten auf wichtige klinisch relevante Bakterienarten hat.
    Notes: Abstract The sterility of the gas Sulfurhexafluoride (SF6) was proved by means of microbiological examinations. It was also shown that Sulfurhexafluoride has no antibacterial influence on important clinically relevant bacteria.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Graefe's archive for clinical and experimental ophthalmology 235 (1997), S. 656-661 
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract • Background: The study was carried out to evaluate the effect of low-dose radiation therapy in patients with age-related macular degeneration. • Methods: One hundred eyes of 78 patients (mean age 72 years) with different forms of age-related macular degeneration were treated with external beam radiotherapy between 1971 and 1989. In four fractions a total dose of 2 Gy was administered over 7 days. Radiation therapy was performed by the conventional 200-kV technique. The mean duration of follow-up period was 7 years (range 0.5 to 20 years). A control group was composed of 96 eyes from patients with AMD who received no therapy. The mean visual acuity at first presentation and the duration of follow-up was the same as in the treatment group. • Results: No difference in visual acuity between the treatment and control groups could be observed. After 1, 2, 5 and 10 years the mean visual acuity was equal in the radiation group and the control group. Even in subgroup analysis regarding only the eyes with exudative forms of AMD, no effect of this treatment strategy could be demonstrated. • Conclusion: Our results suggest that low-dose radiation therapy in patients with age-related macular degeneration has no beneficial effect. However, it must be considered that the dose of 2 Gy is low in comparison to doses used in recently published studies (5–24 Gy).
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Graefe's archive for clinical and experimental ophthalmology 224 (1986), S. 226-229 
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Twelve of 25 patients were treated at the University Eye Clinic in Münster because of retinal detachment due to a macular hole. Partial fluid gas exchange (SF6), vitrectomy and SF6, or vitrectomy and silicone instillation, were used, and the patients were examined both pre- and postoperatively by ultrasonography with particular attention to the situation at the posterior pole. These echographical examinations enabled us to evaluate the following three criteria: (1) staphyloma posticum, (2) stiffness of the retina, and (3) vitreous adhesions. All of these conditions mean that the prognosis will be worse if SF6 gas instillation is used alone. In these cases, a vitrectomy should also be performed or a Klöti-Klemme procedure is useful when stiffness of the retina or staphyloma posticum is present. Preoperative ultrasonography is useful when setting up an adequate therapy plan.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 2 (1998), S. 545-556 
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Within a perturbative approach we investigate decays of charmonium states into baryon-antibaryon pairs. Using a recently proposed wave function for the nucleon and suitable generalizations of it to the hyperons and decouplet baryons, we obtain the decay widths for the $B\overline B$ channels in reasonable agreement with data. An important difference to previous work is the use of the $c$ -quark mass in the perturbative calculation instead of the charmonium mass. As a consequence of this feature our approach possesses the property that the $J/\psi$ and the $\psi'$ decay widths do not scale with a high power of the ratio of their masses.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 2 (1998), S. 705-719 
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Exclusive processes at large momentum transfer $Q$ factor into perturbatively calculable short-distance parts and long-distance hadronic wave functions. Usually, only contributions from the leading Fock states have to be included to leading order in $1/Q$ . We show that for exclusive decays of $P$ -wave quarkonia the contribution from the next-higher Fock state $|{\rm Q}\bar{\rm Q}{\rm g}\rangle$ contributes at the same order in $1/Q$ . We investigate how the constituent gluon attaches to the hard process in order to form colour-singlet final-state hadrons and argue that a single additional long-distance factor is sufficient to parametrize the size of its contribution. Incorporating transverse degrees of freedom and Sudakov factors, our results are perturbatively stable in the sense that soft phase-space contributions are largely suppressed. Explicit calculations yield good agreement with data on $\chi_{{\rm c} J}$ decays into pairs of pions, kaons, and etas. We also comment on $J/\psi$ decays into two pions.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1433-0423
    Keywords: Key words Choroidal malignant melanoma • Ruthenium-106 irradiation • Exudative detachment • Tumor prominence ; Schlüsselwörter Malignes Aderhautmelanom •106Ruthenium-Bestrahlung • Begleitamotio • Tumorprominenz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Fragestellung: Ziel dieser Studie ist es, das Vorhandensein und die Rückläufigkeit der tumorfernen Begleitablatio bei malignen Melanomen mit dem Ansprechen des intraokularen Tumors auf die 106Ruthenium-Bestrahlung zu vergleichen. Patienten und Methoden: 28 Patienten wurden von 1994 bis Anfang 1996 bei V. a. malignes Aderhautmelanom mit einem 106Ruthenium-Applikator bestrahlt. Kontrollen erfolgten 3 und 6 Wochen sowie 3, 6 und 12 Monate postoperativ, später halbjährlich bis jährlich. Studienkriterien erfüllten insgesamt 23 Patienten. Ergebnisse: Initial nach Bestrahlung kam es zu einer Zunahme der Begleitamotio. Bei 15 Patienten (65 %) zeigte sich später eine rasche Reduktion der Begleitamotio, die mit deutlicher Tumorregression (61 %) einherging. Ein Patient hiervon zeigte trotz Rückgang der exsudativen Amotio nur eine geringe Tumorreduktion. Bei 8 Patienten war nach 3 Monaten keine rasche Reduktion der serösen Begleitamotio festzustellen, wobei 2 Patienten bei fehlender Tumorregression erneut bestrahlt und 2 Patienten enukleiert wurden. 1 Patient verstarb. 3 Patienten wiesen trotz zunehmender Begleitamotio eine Tumorregression auf. Schlußfolgerung: Eine rasche Reduktion der serösen Begleitablatio (L 50 % des Ausgangswertes) ca. 3 Monate nach Bestrahlung scheint ein prognostisch günstiger Parameter für eine langfristige Tumorregression zu sein.
    Notes: Background: The purpose of this study was to compare the regression of the tumor-distant exudative detachment that accompanies malignant melanoma with regression of the tumor as a result of ruthenium-106 irradiation. Methods: From 1994 until the beginning of 1996 we treated 28 patients with choroidal malignant melanoma with radioactive plaque therapy. Follow-up examinations were completed 3 and 6 weeks, 3, 6 and 12 months after therapy and finally at 1 year or half-year intervals. Twenty-three patients met the study requirements. Results: Initially, after irradiation there was an increase in the retinal detachment. In 15 patients (65 %) we found rapid regression of the detachment, accompanied by distinct tumor regression (61 %). One of these patients revealed only minor tumor regression in spite of regression of the exudative detachment. Three months after radiation, 8 patients showed no rapid regression of the exudative detachment. Two of these patients had to undergo a second irradiation and 2 were enucleated because of absent tumor regression. One patient died. Three patients showed an increase in the detachment, accompanied by tumor regression. Conclusions: Rapid regression of the exudative detachment (L 50 % of the preoperative detachment) approximately 3 months after irradiation seems to be of good prognostic value for tumor regression.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1433-0423
    Keywords: Key words Ehlers-Danlos syndrome ; Retinal detachment ; Vitrectomy ; Scleral buckling procedure ; Scleral atrophy ; Schlüsselwörter Ehlers-Danlos-Syndrom ; Netzhautablösung ; Vitrektomie ; Plombenoperation ; Skleraatrophie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Fragestellung: Das Ehlers-Danlos-Syndrom (EDS) ist eine erbliche Systemerkrankung des Bindegewebes, die auf einer defekten Kollagensynthese beruht (Kardinalsymptome: Hyperelastizität und Vulnerabilität der Haut, rezidivierende Hämatome bei brüchigen Gefäßen, sekundäre Gelenkdeformitäten). In seltenen Fällen kommt es zu einer Mitbeteiligung der Augen (u. a. Hornhaut- und Sklerarupturen durch Bagatelltraumen, Linsenluxation, rhegmatogene Amotio). Über die Behandlung von Netzhautablösungen bei EDS gibt es nur wenige Berichte, die sich alle auf die konventionelle Ablationschirurgie beschränken. Patient und Methode: Wir berichten über einen 47jährigen Patienten mit EDS Typ VI (okulärer Typ, Lysinhydroxylasemangel) und rhegmatogener Amotio am letzten Auge. Bei ausgeprägter Skleraatrophie war eine Plombenoperation technisch nicht möglich, so daß eine primäre Pars-plana-Vitrektomie erfolgte. Ergebnisse: Während des Eingriffs kam es zu einer ausgeprägten Aderhautamotio und -blutung, die sich postoperativ rasch zurückbildeten. Der Verschluß der Sklerotomien gestaltete sich wegen des Skleraschwunds schwierig. Im weiteren Verlauf waren wegen anteriorer PVR mit Traktionsamotio 2 Revitrektomien notwendig. Unter Tamponade mit 5000 cs Silikonöl liegt die Netzhaut jetzt seit 18 Monaten stabil an,und der Visus beträgt 0,1. Schlußfolgerung: Die primäre Vitrektomie ist eine geeignete Therapie für Netzhautablösungen bei EDS, die wegen Skleraatrophie nicht mit einer episkleralen Plombe operiert werden können. Mit einem komplizierten Verlauf ist jedoch zu rechnen. Deshalb sollte man bei EDS stets Alternativen zu einer primären Vitrektomie erwägen (pneumatische Retinopexie, Ballonplombe, Durapatch mit episkleraler Tasche).
    Notes: Ehlers-Danlos syndrome (EDS) is an hereditary connective tissue disorder caused by defective collagen synthesis, the main features being hyperelasticity and vulnerability of the skin, recurrent bleeding from fragile blood vessels, and secondary deformities of the joints. Ocular involvement is a rare occurrence, e. g., corneal and scleral rupture from minor blunt injury, lens displacement, rhegmatogenous retinal detachment. To date, few reports exist concerning the treatment of retinal detachment in Ehlers-Danlos syndrome, all of them dealing exclusively with conventional scleral buckling surgery. Patient and methods: We report on a 47-year-old male patient suffering from EDS type VI (so-called ocular type, lysine-hydroxylase deficiency). He presented with rhegmatogenous retinal detachment in his only eye. A scleral buckling procedure was not feasible because of marked scleral atrophy. A three-port vitrectomy was therefore carried out. Results: During the operation, pronounced choroidal detachment and bleeding developed, subsiding within weeks postoperatively. Closure of the sclerotomies was difficult due to scleral thinning. Two revitrectomies were necessary because anterior PVR with traction retinal detachment occurred. The last revitrectomy was performed 18 months ago, and the retina has been completely reattached under 5000 cs silicone oil since then. Visual acuity is 0.1. Conclusion: Primary vitrectomy permits successful treatment of retinal detachment in EDS patients if a buckling procedure cannot be performed because of scleral atrophy. However, serious complications may occur. Surgical procedures other than primary vitrectomy should therefore always be carefully considered, e. g., pneumatic retinopexy, temporary balloon, dura patch with episcleral pocket.
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