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Technical Limits (technical + limit)
Selected AbstractsTechnical limits of comparison of step-sectioning,immunohistochemistry and RT-PCR on breast cancer sentinel nodes: a study on methacarn-fixed tissueJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 9b 2009Lorenzo Daniele Abstract The optimal pathological assessment of sentinel nodes (SLNs) in breast cancer is a matter of debate. Currently, multilevel histological evaluation and immunohistochemistry (IHC) are recommended, but alternative RT-PCR procedures have been developed. To assess the reliability of these different procedures, we devised a step-sectioning protocol at 100 micron-intervals of 74 SLNs using methacarn fixation. mRNA was extracted from sections collected from levels 4 to 5. Mammaglobin, CEA and CK19 were used for RT-PCR. mRNA extraction was successful in 69 SLNs. Of these, 7 showed macrometastases (>2mm), 2 showed micrometastases (<2 mm) and 7 showed isolated tumour cells (ITC) by IHC. RT-PCR was positive for the three markers in 6 of 7 macrometastases and in 1 of 2 micrometastases. In the 2 RT-PCR negative cases, metastases were detected only on sections distant from those analysed by RT-PCR. CEA and/or CK19 were positive by RT-PCR in 3 of 7 ITC and in 23 morphologically negative SLNs. In conclusion, the main goal of our study was to show that the use of alternate sections of the same sample for different procedures is the key reason for the discrepancies between molecular and morphological analyses of SLN. We believe that only prospective studies with quantitative mRNA analysis of specific metastatic markers on the whole lymph node can elucidate the utility of molecular assessments of SLN. [source] Medical imaging and MRI in nail disorders: report of 119 cases and review of the literatureDERMATOLOGIC THERAPY, Issue 2 2002Bertrand Richert Radiographs remain the golden standard for exploration of the bony structures located beneath the nail plate, but they provide no information on the perionychium. Until a few years ago the nail apparatus was deprived of investigative medical imaging. Glomus tumor was the only condition that was explored using invasive techniques such as angiography or scintigraphy. High-frequency ultrasound rapidly came up against technical limits. High-resolution magnetic resonance imaging (MRI) offers a superior alternative in detection of distal lesions as well as their relationship with the adjacent structures. MRI provides an accurate analysis of the nail apparatus with detection of lesions as small as 1 mm. This noninvasive technique will allow us to better understand, diagnose, and treat pathologies of the distal phalanx. [source] Capacitors with an Equivalent Oxide Thickness of <0.5 nm for Nanoscale Electronic Semiconductor MemoryADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Seong Keun Kim Abstract The recent progress in the metal-insulator-metal (MIM) capacitor technology is reviewed in terms of the materials and processes mostly for dynamic random access memory (DRAM) applications. As TiN/ZrO2 -Al2O3 -ZrO2/TiN (ZAZ) type DRAM capacitors approach their technical limits, there has been renewed interest in the perovskite SrTiO3, which has a dielectric constant of >100, even at a thickness ,10 nm. However, there are many technical challenges to overcome before this type of MIM capacitor can be used in mass-production compatible processes despite the large advancements in atomic layer deposition (ALD) technology over the past decade. In the mean time, rutile structure TiO2 and Al-doped TiO2 films might find space to fill the gap between ZAZ and SrTiO3 MIM capacitors due to their exceptionally high dielectric constant among binary oxides. Achieving a uniform and dense rutile structure is the key technology for the TiO2 -based dielectrics, which depends on having a dense, uniform and smooth RuO2 layer as bottom electrode. Although the Ru (and RuO2) layers grown by ALD using metal-organic precursors are promising, recent technological breakthroughs using the RuO4 precursor made a thin, uniform, and denser Ru and RuO2 layer on a TiN electrode. A minimum equivalent oxide thickness as small as 0.45 nm with a low enough leakage current was confirmed, even in laboratory scale experiments. The bulk dielectric constant of ALD SrTiO3 films, grown at 370 °C, was ,150 even with thicknesses ,15 nm. The recent development of novel group II precursors made it possible to increase the growth rate largely while leaving the electrical properties of the ALD SrTiO3 film intact. This is an important advancement toward the commercial applications of these MIM capacitors to DRAM as well as to other fields, where an extremely high capacitor density and three-dimensional structures are necessary. [source] The lateral leeway in the habitual intercuspation: experimental studies and literature reviewJOURNAL OF ORAL REHABILITATION, Issue 6 2007K.-H. UTZ summary, The habitual intercuspation is used ubiquitous for manufacturing small dental restorations. However, a little is known on its precision. The aim of the present study was therefore to investigate the unambiguity and accuracy of the habitual occlusion in mounted plaster casts from fully dentate persons. Eighty-one fully dentate volunteers, 36 women and 45 men aged 26·8 ± 6·2 years (18,55 years), with minor fillings and no signs or symptoms of TMD took part in the experiments. Silicone impressions were taken, poured with stone plaster and the obtained casts mounted into Dentatus ARL®, articulators using an individual face bow transfer. Subsequently, the models were transferred to a custom-made measuring articulator where the lateral leeway and the accuracy of the hand-held habitual intercuspation were quantified in the condylar area. Measurements were repeated seven times with the upper cast pushed either to the maximum right or the maximum left intercuspation. The hand-held habitual intercuspation of upper and lower cast proved ambiguous in 57% of pairs of casts. The average lateral leeway of the habitual intercuspation in the condylar area was 0·10 ± 0·05 mm (0,0·51 mm; median 0·07 mm) between the maximum right and left occlusal positions. The average accuracy of three repeated measurements was 0·22 ± 0·09 mm (0·02,1·17 mm; median 0·16 mm). Natural occlusal surfaces in a full dentition do not guarantee an unambiguous habitual intercuspation of the plaster casts. The described leeway and technical limits might be possible causes for occlusal adjustments that are sometimes necessary when inserting restorations manufactured in habitual intercuspation. [source] Novel Process Windows , Gate to Maximizing Process Intensification via Flow ChemistryCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 11 2009V. Hessel Abstract Driven by the economics of scale, the size of reaction vessels as the major processing apparatus of the chemical industry has became bigger and bigger [1, 2]. Consequently, the efforts for ensuring mixing and heat transfer have also increased, as these are scale dependent. This has brought vessel operation to (partly severe) technical limits, especially when controlling harsh conditions, e.g., due to large heat releases. Accordingly, processing at a very large scale has resulted in taming of the chemistry involved in order to slow it down to a technically controllable level. Therefore, reaction paths that already turned out too aggressive at the laboratory scale are automatically excluded for later scale-up, which constitutes a common everyday confinement in exploiting chemical transformations. Organic chemists are barely conscious that even the small-scale laboratory protocols in their textbooks contain many slow, disciplined chemical reactions. Operations such as adding a reactant drop by drop in a large diluted solvent volume have become second nature, but are not intrinsic to the good engineering of chemical reactions. These are intrinsic to the chemical apparatus used in the past. In contrast, today's process intensification [3,12] and the new flow-chemistry reactors on the micro- and milli-scale [13,39] allow such limitations to be overcome, and thus, enable a complete, ab-initio type rethinking of the processes themselves. In this way, space-time yields and the productivity of the reactor can be increased by orders of magnitude and other dramatic performance step changes can be achieved. A hand-in-hand design of the reactors and process re-thinking is required to enable chemistry rather than subduing chemistry around the reactor [40]. This often leads to making use of process conditions far from conventional practice, under harsh environments, a procedure named here as Novel Process Windows. [source] | ||||||||||