62 research outputs found
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Energy-Dependent RBS Channelling Analysis of Epitaxial ZnO Layers Grown on ZnO by RF-Magnetron Sputtering
The transparent conducting oxides ZnO and ZnO:Al are interesting materials for a wide range of applications. Several of these applications need a large area, single crystalline, and specially doped thin layers. A common technique for the fabrication of those layers is RF (radio frequency) -magnetron sputtering. The investigation of the crystal quality of such layers requires methods of analysis that are destruction free and that are able to obtain information about the concentration and type of defects versus depth. One such option is the Rutherford backscattering spectroscopy (RBS) in channelling mode. In this work, we exploit the channelling effect and its energy dependence, which are sensitive to the type of defects. By using appropriate software and measuring RBS channelling spectra with different beam energies, we were able to determine the depth distribution of point defects and dislocation loops. The presence of dislocation loops was proven using other previously applied analysis methods. The main advantage of RBS in channelling mode is the quantification of point defects, which can be important for defining the electrical and optical properties of such layers. The technique demonstrated is applicable to other defective crystals or thin crystalline layers. © 2019 by the authors. Licensee MDPI, Basel, Switzerland
FORMATION OF GaN NANOCRYSTALS IN SiO2/Si
Ga and N ions were implanted into a silicon dioxide layer on crystalline silicon. Ion energies were adjusted for obtaining an
overlap of the depth profiles at a depth close to the surface. The chosen ion fluences result in maximum concentrations of about
9at.%. Rapid thermal annealing with halogen lamps was performed in nitrogen/ammonia ambient. Optimum annealing conditions
for retaining the implanted species within the samples were found to be 1000°C and times between 30 and 120 s. Formation
of Ga-N bonds was demonstrated by extended X-ray absorption fine structure measurements. Best results were obtained
after annealing at 1000°C for 90 s. In this case pictures of cross section transmission electron microscopy show dark areas
which are related to the higher mass of Ga atoms. High-resolution pictures reveal the existence of nanocrystals
Ion irradiation-induced sinking of Ag nanocubes into substrates
Ion irradiation can cause burrowing of nanoparticles in substrates, strongly
depending on the material properties and irradiation parameters. In this study,
we demonstrate that the sinking process can be accomplished with ion
irradiation of cube-shaped Ag nanoparticles on top of silicon; how ion
channeling affects the sinking rate; and underline the importance of the
amorphous state of the substrate upon ion irradiation. Based on our
experimental findings, the sinking process is described as being driven by
capillary forces enabled by ion-induced plastic flow of the substrate.Comment: the manuscript has 25 pages and 6 figure
The Hematopoietic System–specific Minor Histocompatibility Antigen HA-1 Shows Aberrant Expression in Epithelial Cancer Cells
Allogeneic stem cell transplantation (SCT) can induce curative graft-versus-tumor reactions in patients with hematological malignancies and solid tumors. The graft-versus-tumor reaction after human histocompatibility leukocyte antigen (HLA)-identical SCT is mediated by alloimmune donor T cells specific for polymorphic minor histocompatibility antigens (mHags). Among these, the mHag HA-1 was found to be restricted to the hematopoietic system. Here, we report on the HA-1 ribonucleic acid expression by microdissected carcinoma tissues and by single disseminated tumor cells isolated from patients with various epithelial tumors. The HA-1 peptide is molecularly defined, as it forms an immunogenic peptide ligand with HLA-A2 on the cell membrane of carcinoma cell lines. HA-1–specific cytotoxic T cells lyse epithelial tumor cell lines in vitro, whereas normal epithelial cells are not recognized. Thus, HA-1–specific immunotherapy combined with HLA-identical allogeneic SCT may now be feasible for patients with HA-1+ carcinomas
Migration behaviour of selenium implanted into polycrystalline 3C–SiC
Please read abstract in the article.The National Research Foundation and The World Academy of Science.http://www.journals.elsevier.com/vacuum2021-05-01hj2020Physic
Optimizing MATRix as remission induction in PCNSL: de-escalated induction treatment in newly diagnosed primary CNS lymphoma
Background: Primary diffuse large B-cell lymphoma (DLBCL) of the central nervous system (PCNSL) is a rare disorder with an increasing incidence over the past decades. High-level evidence has been reported for the MATRix regimen (high-dose methotrexate (HD-MTX), high-dose AraC (HD-AraC), thiotepa and rituximab) followed by high-dose chemotherapy and autologous stem cell transplantation (HCT-ASCT) supporting this approach to be considered a standard therapy in newly diagnosed PCNSL patients ≤ 70 years. However, early treatment-related toxicities (predominantly infectious complications), occurring in up to 28% per MATRix cycle, diminish its therapeutic success. Furthermore, sensitivity to first-line treatment is an independent prognostic factor for improved overall survival (OS) in PCNSL. Thus, patients achieving early partial remission (PR) after 2 cycles of MATRix might be over-treated with 4 cycles, in the context of consolidation HCT-ASCT. Methods: This is an open-label, multicentre, randomized phase III trial with two parallel arms. 326 immunocompetent patients with newly diagnosed PCNSL will be recruited from 37 German, 1 Austrian and 12 UK sites. Additional IELSG (International Extranodal Lymphoma Study Group) sites are planned. The objective is to demonstrate superiority of a de-escalated and optimised remission induction treatment strategy, followed by HCT-ASCT. Randomization (1:1) will be performed after completion of all screening procedures. Patients in Arm A (control treatment) will receive 4 cycles of MATRix. Patients in Arm B (experimental treatment) will receive a pre-phase (R/HD-MTX), followed by 2 cycles of MATRix. Patients in both arms achieving PR or better will proceed to HCT-ASCT (BCNU, thiotepa). The primary endpoint of the study is event-free-survival (EFS), defined as time from randomization to premature end of treatment due to any reason, lymphoma progression or death whichever occurs first. Secondary endpoints include OS, progression free survival (PFS), toxicity, neurocognitive impairment and quality of life. Minimal follow-up is 24 months. Discussion: Current treatment options for PCNSL in patients ≤ 70 years have improved remarkably over recent years. However, the potential efficacy benefits are offset by an increased incidence of short-term toxicities which can impact on treatment delivery and hence on survival outcomes. In patients ≤ 70 years with newly diagnosed PCNSL addressing the need to reduce treatment-related toxicity by de-escalating and optimising the induction phase of treatment, is a potentially attractive treatment strategy. Trial registration: German clinical trials registry DRKS00022768 registered June 10th, 2021
Формирование фотоприемных структур ИК-диапазона путем пересыщения кремния теллуром
The Si layers doped with Te up to the concentrations of (3–5)1020 cm–3 have been formed via ion implantation and pulsed laser melting. It is found, 70–90 % of the embedded impurity atoms are in substitution states in the silicon lattice. These layers have revealed significant absorption (35–66 %) in the wavelength λ range of 1100–2500 nm. In this case, the absorption coefficient increases with the λ growth. The absorption spectra of the implanted layers after pulsed laser melting, equilibrium furnace annealing, and rapid thermal annealing have been compared. It is shown that equilibrium furnace annealing increases the photon absorption by 4 % in the wavelength range of 1100–2500 nm in comparison with virgin Si. After rapid thermal annealing, the photon absorption in the IR-range increases only by 2 %.Слои кремния, легированные теллуром до концентраций (3–5)1020 см–3, получены ионной имплантацией с последующим импульсным лазерным отжигом. Показано, что 70–90 % внедренной примеси находится в позиции замещения в решетке кремния. Слои, гиперпересыщенные теллуром, проявляют существенное поглощение (35–66 %) в области длин волн 1100–2500 нм, причем коэффициент поглощения увеличивается с ростом длины волны. Проведено сравнение спектров поглощения имплантированных слоев после лазерного отжига, а также после равновесного и быстрого термического отжигов. Показано, что равновесный отжиг после имплантации ионов теллура увеличивает поглощение фотонов в области длин волн 1100–2500 нм на 4 % по сравнению с неимплантированным кремнием. После быстрого термического отжига поглощение в ИК-области возрастает лишь на 2 %
27. Vorlesung (03.02.2021): Radioaktivität
Vorlesungsinhalt: Einige Begriffe der Atom- und Kernphysik; Zerfallsgesetz, Aktivität; Dosimetrie und biologische Wirkung radioaktiver Strahlun
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