Metrology for electron-beam lithography and resist contrast at the sub-10 nm scale

Exploring the resolution limit of electron-beam lithography is of great interest both scientifically and technologically. However, when electron-beam lithography approaches its resolution limit, imaging and metrology of the fabricated structures by using standard scanning electron microscopy become difficult. In this work, the authors adopted transmission-electron and atomic-force microscopies to improve the metrological accuracy and to analyze the resolution limit of electron-beam lithography. With these metrological methods, the authors found that sub-5 nm sparse features could be readily fabricated by electron-beam lithography, but dense 16 nm pitch structures were difficult to yield. Measurements of point- and line-spread functions suggested that the resolution in fabricating sub-10 nm half-pitch structures was primarily limited by the resist-development processes, meaning that the development rates depended on pattern density and/or length scale.China Scholarship Council (Fellowship)United States. Dept. of Energy. Center for Excitonics (Award DE-SC0001088)Information Storage Industry ConsortiumNanoelectronics Research InitiativeNational Science Foundation (U.S.

Electrochemical development of hydrogen silsesquioxane by applying an electrical potential

We present a new method for developing hydrogen silsesquioxane (HSQ) by using electrical potentials and deionized water. Nested-L test structures with a pitch as small as 9 nm were developed using this electrochemical technique in saline solution without adding hydroxyl ions. Furthermore, we showed that high-resolution structures can be electrochemically developed in deionized water alone. Electrochemical development is controlled by the applied voltage and may overcome several of the limitations discussed for alkaline developers, such as poor hydroxyl anion diffusion and charge repulsion effects in small trenches.National Science Foundation (U.S.)Massachusetts Institute of Technology. Materials Processing CenterMassachusetts Institute of Technology. Center for Materials Science and Engineerin

Plasmonic Control of Radiative Properties of Semiconductor Quantum Dots Coupled to Plasmonic Ring Cavities

In recent years, a lot of effort has been made to achieve controlled delivery of target particles to the hotspots of plasmonic nanoantennas, in order to probe and/or exploit the extremely large field enhancements produced by such structures. While in many cases such high fields are advantageous, there are instances where they should be avoided. In this work, we consider the implications of using the standard nanoantenna geometries when colloidal quantum dots are employed as target entities. We show that in this case, and for various reasons, dimer antennas are not the optimum choice. Plasmonic ring cavities are a better option despite low field enhancements, as they allow collective coupling of many quantum dots in a reproducible and predictable manner. In cases where larger field enhancements are required, or for larger quantum dots, nonconcentric ring-disk cavities can be employed instead

Serum IgG against Simian Virus 40 antigens are hampered by high levels of sHLA-G in patients affected by inflammatory neurological diseases, as multiple sclerosis

Background: Many investigators detected the simian polyomavirus SV40 footprints in human brain tumors and neurologic diseases and recently it has been indicated that SV40 seems to be associated with multiple sclerosis (MS) disease. Interestingly, SV40 interacts with human leukocyte antigen (HLA) class I molecules for cell entry. HLA class I antigens, in particular non-classical HLA-G molecules, characterized by an immune-regulatory function, are involved in MS disease, and the levels of these molecules are modified according with the disease status. Objective: We investigated in serum samples, from Italian patients affected by MS, other inflammatory diseases (OIND), non-inflammatory neurological diseases (NIND) and healthy subjects (HS), SV40-antibody and soluble sHLA-G and the association between SV40-prevalence and sHLA-G levels. Methods: ELISA tests were used for SV40-antibodies detection and sHLA-G quantitation in serum samples. Results: The presence of SV40 antibodies was observed in 6 % of patients affected by MS (N = 4/63), 10 % of OIND (N = 8/77) and 15 % of NIND (N = 9/59), which is suggestive of a lower prevalence in respect to HS (22 %, N = 18/83). MS patients are characterized by higher sHLA-G serum levels (13.9 \ub1 0.9 ng/ml; mean \ub1 St. Error) in comparison with OIND (6.7 \ub1 0.8 ng/ml), NIND (2.9 \ub1 0.4 ng/ml) and HS (2.6 \ub1 0.7 ng/ml) subjects. Interestingly, we observed an inverse correlation between SV40 antibody prevalence and sHLA-G serum levels in MS patients. Conclusion: The data obtained showed a low prevalence of SV40 antibodies in MS patients. These results seems to be due to a generalized status of inability to counteract SV40 infection via antibody production. In particular, we hypothesize that SV40 immune-inhibitory direct effect and the presence of high levels of the immune-inhibitory HLA-G molecules could co-operate in impairing B lymphocyte activation towards SV40 specific peptides

Taxa de geração de resíduos da construção civil em edificações na cidade de João Pessoa

O objetivo deste trabalho foi determinar a quantidade de resíduos da construção civil (RCC) em função da área construída da edificação, para efetuar acompanhamento e fiscalização mais eficazes da geração e destinação final em dada obra. Foi escolhida uma amostra representativa das edificações em fase de construção na cidade de João Pessoa. Uma ficha para coleta das características e acompanhamento de volume de RCC descartado ao longo do cronograma de execução da construção foi fornecida aos gestores das edificações; a partir do volume descartado pelas construtoras, determinou-se a massa de RCC gerado em cada obra utilizando uma massa unitária de 1.025 kg m-3 Os resultados indicaram uma taxa média de geração de RCC classe A de 86,27 kg m-². Ainda para os RCC classe A, foram definidos os limites inferior e superior com 90% de confiança para a taxa de geração: 62,31 e 136,02 kg m-² respectivamente. A partir desses valores, o controle da geração e disposição de RCC pode ser realizado pelos órgãos competentes, dando o indicativo de quais obras podem estar infringindo a legislação vigente no tocante à destinação de tais resíduos