197,007 research outputs found
Ictal fear versus panic attacks: First results from conversation analysis of clinical interviews
No full textGülich E, Woermann FG, Rullkoetter N, Gerhards S, Lindner M, Schoendienst M. Ictal fear versus panic attacks: First results from conversation analysis of clinical interviews. EPILEPSIA. 2005;46(6):343
Ion beam synthesis of diamond-like carbon thin films containing copper nanocrystals
No full textAmorphous carbon thin films containing 0-50 at. % Cu have been grown by mass selected ion beam deposition in order to synthesize isolated Cu nanoparticles within a diamond-like matrix. Raman spectroscopy and x-ray photoelectron spectroscopy show that the sp(3) content of the matrix decreases with increasing Cu content. Simultaneously, the mean particle size of the embedded Cu nanocrystals increases, as x-ray diffraction and transmission electron microscopy analysis reveal. There is apparently no dependence of the matrix structure on the Cu+ ion energy, while the Cu content is strongly influenced by this deposition parameter. (C) 2003 American Institute of Physics
Self-organized nanoscale multilayer growth in hyperthermal ion deposition
No full textIn the course of thin film growth by co-deposition of low energy mass selected carbon and metal (Au or Fe) ions, an effect of self-organization was found. Although carbon and metal ions were deposited quasi-simultaneously, a multilayer film structure of alternately metal-rich and metal-deficient layers was grown. The period of these layers is of the order of a few nanometers (similar to6-20 nm), and the metal-rich layers consist of metallic nanocrystals. The multilayer formation process is discussed in comparison with earlier studies on C-Cu and C-Ag films with respect to the structural properties of small clusters of the different metals, the influence of sputtering yields, and the deposition parameters. For a variety of compound thin film materials we expect a multilayer structure to develop during simultaneous sputter deposition or ion beam deposition of the components. The suppositions for this scenario are: (a) the deposited elements are immiscible or there are immiscible phases of a compound material, (b) the sputtering yields of the film components imposed by the impinging species are in an appropriate range, and (c) one compound segregates at the surface
Changes in the electronic structure of gold particles upon thiol adsorption as a function of the mean particle size
No full textWe studied the interaction of adsorbed thiol molecules with gold nanoparticles as a function of the mean particle size. The results obtained from MXPS (monochromated X-Ray Photoelectron Spectroscopy) measurements showed that attachment of the thiol sulfur headgroup onto the cluster surface leads to a positive binding energy shift in the Au 4f core-level. The absence of line width broadening upon adsorption indicates that these changes affect the whole particle and not only the particle surface, where the actual Au-S bond is located. The positive binding energy shift depends on the cluster size and increases with decreasing diameter. A maximum shift of 0.41 eV could be measured for the smallest particles (similar to 1 nm). The valence band exhibited positive binding energy shifts similar to the Au 4f core-levels, but smaller in absolute values. Changes in the valence band shape were interpreted as re-hybridization of Au 5d electrons due to the creation of Au-S bonds. Furthermore, we observed a disappearance of the Fermi edge upon thiol adsorption, which we attribute to a sulfur-induced metal-insulator-transition of the gold cluster. (c) 2005 Elsevier B.V. All rights reserved
Nucleation mechanism of the seed of tetrapod ZnO nanostructures
No full textTetrapod zinc oxide (T-ZnO) nanorods have been synthesized by evaporation and recondensation of metallic Zn under ambient conditions. The total sizes of the T-ZnO nanostructures range from 300 nm to 15 mu m with leg diameters of about 30 to 650 nm, depending on the deposition temperature. A detailed high-resolution electron microscopy analysis showed that the center core of T-ZnO nanorods consists of four hexagonal grains with a twinlike relation. The nucleation and growth mechanism has been generated on the basis of energy considerations during a phase transition from a fullerenelike ZnO cluster to a nanometer-sized tetrahedron, which is directly visible in our high-resolution transmission electron microscopy investigations. (c) 2005 American Institute of Physics
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
New tools for old drugs: Functional genetic screens to optimize current chemotherapy
No full textDespite substantial advances in the treatment of various cancers, many patients still receive anti-cancer therapies that hardly eradicate tumor cells but inflict considerable side effects. To provide the best treatment regimen for an individual patient, a major goal in molecular oncology is to identify predictive markers for a personalized therapeutic strategy. Regarding novel targeted anti-cancer therapies, there are usually good markers available. Unfortunately, however, targeted therapies alone often result in rather short remissions and little cytotoxic effect on the cancer cells. Therefore, classical chemotherapy with frequent long remissions, cures, and a clear effect on cancer cell eradication remains a corner stone in current anti-cancer therapy. Reliable biomarkers which predict the response of tumors to classical chemotherapy are rare, in contrast to the situation for targeted therapy. For the bulk of cytotoxic therapeutic agents, including DNA-damaging drugs, drugs targeting microtubules or antimetabolites, there are still no reliable biomarkers used in the clinic to predict tumor response. To make progress in this direction, meticulous studies of classical chemotherapeutic drug action and resistance mechanisms are required. For this purpose, novel functional screening technologies have emerged as successful technologies to study chemotherapeutic drug response in a variety of models. They allow a systematic analysis of genetic contributions to a drug-responsive or -sensitive phenotype and facilitate a better understanding of the mode of action of these drugs. These functional genomic approaches are not only useful for the development of novel targeted anti-cancer drugs but may also guide the use of classical chemotherapeutic drugs by deciphering novel mechanisms influencing a tumor's drug response. Moreover, due to the advances of 3D organoid cultures from patient tumors and in vivo screens in mice, these genetic screens can be applied using conditions that are more representative of the clinical setting. Patient-derived 3D organoid lines furthermore allow the characterization of the "essentialome", the specific set of genes required for survival of these cells, of an individual tumor, which could be monitored over the course of treatment and help understanding how drug resistance evolves in clinical tumors. Thus, we expect that these functional screens will enable the discovery of novel cancer-specific vulnerabilities, and through clinical validation, move the field of predictive biomarkers forward. This review focuses on novel advanced techniques to decipher the interplay between genetic alterations and drug response
Self-assembled nano-scale multilayer formation using physical vapor deposition methods
No full textSelf-assembled alternating carbon and metal layers have been produced by concurrent deposition of carbon and metal atoms using both dc reactive sputter deposition and mass selected ion beam deposition. High-resolution transmission electron micrographs clearly show the alternating metal-rich and -deficient layers with periodicities in the nanometer scale. The appearance of a multilayer structure and its periodicity strongly depend on the deposition parameters, i.e. the metal species, the provided stoichiometry and the ion energy. Here, we discuss the similarities and differences of the parameters used in both physical vapor deposition methods on the impact on the multilayer structures. (c) 2005 Elsevier B.V. All rights reserved
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