Studying alumina boundary migration using combined microscopy techniques

Thermal grooving and migration of grain boundaries in alumina have been investigated using a variety of microscopy techniques. Using two different methods, polycrystalline alumina was used to investigate wet, (implying the presence of a glassy phase), and dry grain boundaries. In the first, single-crystal Al2O3 was hot-pressed via liquid phase sintering (LPS) to polycrystalline alumina with an anorthite glass film at the interface. Pulsed laser deposition was used to deposit approximately 100-nm thick glass films. Specimens were annealed in air at 1650°C for 20 h to induce boundary migration. Boundary characterization was carried out using visible light (VLM) and scanning electron (SEM) microscopies. Effects on migration due to surface orientation of grains were investigated using electron backscatter diffraction (EBSD). The second method dealt with heat treating dry boundaries in polycrystalline alumina to monitor boundary migration behavior via remnant thermal grooves. Heat treatments were conducted at 1650°C for 30 min. The same region of the sample was mapped using VLM and atomic force microscopy (AFM) and followed over a series of 30 min heat treatments. Boundary migration through a pore trapped inside the grain matrix was of particular interest

Imexon augments sensitivity of human lymphoma cells to ionizing radiation: in vitro experimental study

BACKGROUND: Imexon is an aziridine-containing small pro-oxidant molecule with promising antitumor activity in myeloma, lymphoma and lung and pancreatic cancer. Imexon is already in clinical trials in patients with advanced solid tumors. The present study examined the effects of imexon on H9 and Raji lymphoma cell lines in vitro when given in combination with ionizing radiation. MATERIALS AND METHODS: H9 and Raji lymphoma cells were grown in culture and exposed to imexon, radiation, or both. Cells were assessed for cell viability, glutathione content, induction of apoptosis, cell cycle distribution and also subject to Western blot analysis. RESULTS: Imexon inhibited cell proliferation in a dose-dependent manner. Imexon, given for 48 h prior to irradiation at a clinically achievable dose of 40 muM, potently enhanced the cell radiosensitivity. Imexon enhanced radiation-induced apoptosis and accumulated cells in G2/M phase of the cell cycle. Imexon induced caspase-3 activation and PARP cleavage. Alterations in glutathione levels were not observed at 40 microM of imexon. CONCLUSION: In conclusion, imexon efficiently augmented lymphoma cell radiosensitivity independently of glutathione and the underlying mechanisms include induction of apoptosis and cell cycle redistribution

High Spatial Resolution Time-of-Flight Secondary Ion Mass Spectrometry for the Masses: A Novel Orthogonal ToF FIB-SIMS Instrument with In Situ

We describe the design and performance of an orthogonal time-of-flight (TOF) secondary ion mass spectrometer that can be retrofitted to existing focused ion beam (FIB) instruments. In particular, a simple interface has been developed for FIB/SEM instruments from the manufacturer Tescan. Orthogonal extraction to the mass analyser obviates the need to pulse the primary ion beam and does not require the use of monoisotopic gallium to preserve mass resolution. The high-duty cycle and reasonable collection efficiency of the new instrument combined with the high spatial resolution of a gallium liquid metal ion source allow chemical observation of features smaller than 50 nm. We have also demonstrated the integration of a scanning probe microscope (SPM) operated as an atomic force microscope (AFM) within the FIB/SEM-SIMS chamber. This provides roughness information, and will also allow true three dimensional chemical images to be reconstructed from SIMS measurements

Identifying core MRI sequences for reliable automatic brain metastasis segmentation

BACKGROUND Many automatic approaches to brain tumor segmentation employ multiple magnetic resonance imaging (MRI) sequences. The goal of this project was to compare different combinations of input sequences to determine which MRI sequences are needed for effective automated brain metastasis (BM) segmentation. METHODS We analyzed preoperative imaging (T1-weighted sequence ± contrast-enhancement (T1/T1-CE), T2-weighted sequence (T2), and T2 fluid-attenuated inversion recovery (T2-FLAIR) sequence) from 339 patients with BMs from seven centers. A baseline 3D U-Net with all four sequences and six U-Nets with plausible sequence combinations (T1-CE, T1, T2-FLAIR, T1-CE + T2-FLAIR, T1-CE + T1 + T2-FLAIR, T1-CE + T1) were trained on 239 patients from two centers and subsequently tested on an external cohort of 100 patients from five centers. RESULTS The model based on T1-CE alone achieved the best segmentation performance for BM segmentation with a median Dice similarity coefficient (DSC) of 0.96. Models trained without T1-CE performed worse (T1-only: DSC = 0.70 and T2-FLAIR-only: DSC = 0.73). For edema segmentation, models that included both T1-CE and T2-FLAIR performed best (DSC = 0.93), while the remaining four models without simultaneous inclusion of these both sequences reached a median DSC of 0.81-0.89. CONCLUSIONS A T1-CE-only protocol suffices for the segmentation of BMs. The combination of T1-CE and T2-FLAIR is important for edema segmentation. Missing either T1-CE or T2-FLAIR decreases performance. These findings may improve imaging routines by omitting unnecessary sequences, thus allowing for faster procedures in daily clinical practice while enabling optimal neural network-based target definitions

Determination of nutrient salts by automatic methods both in seawater and brackish water: the phosphate blank

9 páginas, 2 tablas, 2 figurasThe main inconvenience in determining nutrients in seawater by automatic methods is simply solved: the preparation of a suitable blank which corrects the effect of the refractive index change on the recorded signal. Two procedures are proposed, one physical (a simple equation to estimate the effect) and the other chemical (removal of the dissolved phosphorus with ferric hydroxide).Support for this work came from CICYT (MAR88-0245 project) and Conselleria de Pesca de la Xunta de GaliciaPeer reviewe

Das Elektrocardiogram (EKG) des isolierten Schneckenherzens (Helix pomatia L.)

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Repeated and preemptive palliative radiotherapy of symptomatic hepatomegaly in a patient with advanced myelofibrosis

BACKGROUND: Patients with advanced myelofibrosis often suffer from symptomatic extramedullary hematopoiesis in spleen and/or liver. In case of drug-refractory disease splenomegaly is treated surgically, whereas hepatomegaly is palliated by radiotherapy (RT). CASE REPORT: A 56-year-old man with advanced and drug-refractory myelofibrosis suffered from extensive hepatomegaly with severe upper abdominal pain, satiety, weight loss, and fatigue 1.5 years after splenectomy. The patient was treated periodically with fractionated RT to the liver in order to obtain symptom control and to prevent severe symptom recurrence. RESULTS: After 2 Gy fractionated RT to a treatment field encompassing nearly the whole liver, symptoms improved and liver size decreased without severe side effects. This treatment regimen was successfully conducted 3 times in trimonthly intervals. Because symptoms recurred periodically, we then continued RT on a preemptive basis in monthly intervals and with single-dose irradiation. The patient responded well to 1 Gy preemptive single-dose RT to the liver, but not to 0.5 Gy single-dose partial liver irradiation. CONCLUSION: RT is effective in palliation of hepatomegaly in advanced myelofibrosis. Even preemptive RT can benefit selected patients with advanced disease and periodical recurrence of symptoms

Rayleigh instability induced SiC/SiO2 necklace like nanostructures

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