Exploration of Directed Self Assembly Polymers

Directed Self Assembly (DSA) is an attractive alternative to 193i and multiple patterning. Various polymers were investigated to find the possible structures that can be created with them. Previous research was used to determine the process used. Two surface treatments, a polymer brush and hexamethyldisilazane (HMDS) were used to help the polymers phase separate into their respective structure. The first polymer a polystyrene (PS) block polydimethylsiloxane (PDMS) resulted in de-wetting and film non-uniformity that prevented measurement. The second polymer a PS block polyethylene oxide (PEO) resulted in crystallization if the PEO ratio was too high at 40% mole. When the PEO ratio was low enough at 29% mole and on a PS brush polymer via holes 30 nm in diameter were found using phase imaging on an Atomic Force Microscope (AFM). Repeat samples of the via holes de-wetted from the surface likely due to surface contamination preventing the brush polymer from adhering to the surface

Directed Self Assembly

Current Challenges to manufacturing •Limits of 193i and multiple patterning are approaching •10nm resolution has been demonstrated with multiple patterning •EUV as an alternative is expensive with low throughput Advantages of Directed Self Assembly •Resolution of 20nm and possibly lower •Can be integrated with current patterning techniques •Inexpensive Disadvantages of DSA •Complex patterns can be difficult or impossible to form •Has to be integrated into an existing lithography process •Pattern formation may take large amounts of tim

Aquaporins Have Regional Functions in Development of Refractive Index in the Zebrafish Eye Lens

Purpose: In the eye lens, cytosolic protein concentrations increase progressively from the periphery to the center, contributing to the gradient of refractive index (GRIN). Aquaporins are membrane proteins of lens fiber cells that regulate water transport and adhesion and interact with cytoskeletal proteins. This study investigates how these membrane proteins contribute to proper development of the lens GRIN. Methods: Loss-of-function deletions of aqp0a and/or aqp0b in zebrafish were generated using CRISPR/Cas9 gene editing. Lenses of single aqp0a-/- mutants, single aqp0b-/- mutants, and double aqp0a-/-/aqp0b-/- mutants from larval to elderly adult stages were measured using x-ray Talbot interferometry at SPring8 in Japan. The three-dimensional GRIN profiles in two orthogonal cross-sectional planes of each lens were analyzed and compared with in vivo images and previous results obtained from wild-type lenses. Results: Single aqp0a-/- mutants tended to show asymmetric GRIN profiles, with the central plateau regions shifted anteriorly. Single aqp0b-/- mutants had smooth, symmetric GRIN profiles throughout development until spoke opacities appeared in several extremely old samples. Double aqp0a-/-/aqp0b-/- mutants showed lower magnitude GRIN profiles, as well as dips in the central plateau region. Conclusions: These findings suggest that Aqp0a and Aqp0b have region-specific functions in the lens: Aqp0a is active peripherally, regulating centralization of the plateau region, and this function cannot be compensated for by Aqp0b. In the lens center, either Aqp0a or Aqp0b is required for formation of the plateau region, as well as for the GRIN to reach its maximum magnitude in mature lenses

A Two-Gene Balance Regulates Salmonella Typhimurium Tolerance in the Nematode Caenorhabditis elegans

Lysozymes are antimicrobial enzymes that perform a critical role in resisting infection in a wide-range of eukaryotes. However, using the nematode Caenorhabditis elegans as a model host we now demonstrate that deletion of the protist type lysozyme LYS-7 renders animals susceptible to killing by the fatal fungal human pathogen Cryptococcus neoformans, but, remarkably, enhances tolerance to the enteric bacteria Salmonella Typhimurium. This trade-off in immunological susceptibility in C. elegans is further mediated by the reciprocal activity of lys-7 and the tyrosine kinase abl-1. Together this implies a greater complexity in C. elegans innate immune function than previously thought

Structural and effective connectivity reveals potential network-based influences on category-sensitive visual areas

Visual category perception is thought to depend on brain areas that respond specifically when certain categories are viewed. These category-sensitive areas are often assumed to be modules (with some degree of processing autonomy) and to act predominantly on feedforward visual input. This modular view can be complemented by a view that treats brain areas as elements within more complex networks and as influenced by network properties. This network-oriented viewpoint is emerging from studies using either diffusion tensor imaging to map structural connections or effective connectivity analyses to measure how their functional responses influence each other. This literature motivates several hypotheses that predict category-sensitive activity based on network properties. Large, long-range fiber bundles such as inferior fronto-occipital, arcuate and inferior longitudinal fasciculi are associated with behavioural recognition and could play crucial roles in conveying backward influences on visual cortex from anterior temporal and frontal areas. Such backward influences could support top-down functions such as visual search and emotion-based visual modulation. Within visual cortex itself, areas sensitive to different categories appear well-connected (e.g., face areas connect to object- and motion sensitive areas) and their responses can be predicted by backward modulation. Evidence supporting these propositions remains incomplete and underscores the need for better integration of DTI and functional imaging

The prospectivity of a potential shale gas play: An example from the southern Pennine Basin (central England, UK)

During the Serpukhovian (late Mississippian) Stage, the Pennine Basin, now underlying much of northern England, consisted of a series of interlinked sub-basins that developed in response to the crustal extension north of the Hercynic orogenic zone. For the current study, mudstone samples of the Morridge Formation from two sub-basins located in the south-eastern part of the Pennine Basin were collected from the Carsington Dam Reconstruction C3 Borehole (Widmerpool Gulf sub-basin) and the Karenight 1 Borehole (Edale Gulf sub-basin). Detailed palynological analyses indicate that aside from the dominant (often 90% or more) heterogeneous amorphous organic matter (AOM), variable abundances of homogeneous AOM and phytoclasts are present. To complement the palynological dataset, a suite of geochemical and mineralogical techniques were applied to evaluate the prospectivity of these potentially important source rocks. Changes in the carbon isotope composition of the bulk organic fraction (δ13COM) suggest that the lower part (Biozone E2a) of Carsington DR C3 is markedly more influenced by terrigenous kerogen than the upper part of the core (Biozones E2a3–E2b1). The Karenight 1 core yielded more marine kerogen in the lower part (Marine Bands E1–E2b) than the upper part (Marine Band E2b). Present day Rock-Eval™ Total Organic Carbon (TOC) surpasses 2% in most samples from both cores, a proportion suggested by Jarvie (2012) that defines prospective shale gas reservoirs. However, when the pyrolysable component that reflects the generative kerogen fraction is considered, very few samples reach this threshold. The kerogen typing permits for the first time the calculation of an original hydrogen index (HIo) and original total organic carbon (TOCo) for Carboniferous mudstones of the Pennine Basin. The most prospective part of Carsington DR C3 (marine bands E2b1–E2a3) has an average TOCo of 3.2% and an average HIo of 465 mg/g TOCo. The most prospective part of Karenight 1 (242.80–251.89 m) is characterized by an average TOCo of 9.3% and an average HIo of 504 mg/g TOCo. Lastly, X-ray diffraction (XRD) analysis confirms that the siliceous to argillaceous mudstones contain a highly variable carbonate content. The palynological, geochemical and mineralogical proxies combined indicate that marine sediments were continuously being deposited throughout the sampled intervals and were punctuated by episodic turbiditic events. The terrestrial material, originating from the Wales-Brabant High to the south of the Pennine Basin, was principally deposited in the Widmerpool Gulf, with much less terrigenous organic matter reaching the Edale Gulf. As a consequence, the prospective intervals are relatively thin, decimetre-to meter-scale, and further high resolution characterization of these intervals is required to understand variability in prospectivitiy over these limited intervals

Selection on Alleles Affecting Human Longevity and Late-Life Disease: The Example of Apolipoprotein E

It is often claimed that genes affecting health in old age, such as cardiovascular and Alzheimer diseases, are beyond the reach of natural selection. We show in a simulation study based on known genetic (apolipoprotein E) and non-genetic risk factors (gender, diet, smoking, alcohol, exercise) that, because there is a statistical distribution of ages at which these genes exert their influence on morbidity and mortality, the effects of selection are in fact non-negligible. A gradual increase with each generation of the ε2 and ε3 alleles of the gene at the expense of the ε4 allele was predicted from the model. The ε2 allele frequency was found to increase slightly more rapidly than that for ε3, although there was no statistically significant difference between the two. Our result may explain the recent evolutionary history of the epsilon 2, 3 and 4 alleles of the apolipoprotein E gene and has wider relevance for genes affecting human longevity

Pratos e mais pratos: louças domésticas, divisões culturais e limites sociais no Rio de Janeiro, século XIX

Reply to ten comments on a paper published in the last issue of this journal. The discussion follows along six main lines: History museums, identity, ideology and the category of nation; the need of material collections and their modalities: patrimonial, operational, virtual; theater versus laboratory; visitors and their ambiguities; Public History: the museum and the academy.Resposta aos comentários de dez especialistas que contribuíram no debate de texto publicado no último número desta revista. A discussão orientou-se segundo seis tópicos principais: museus históricos, identidade, ideologia e a categoria de nação; a necessidade de acervos materiais e suas modalidades: acervo patrimonial, operacional, virtual; teatro versus laboratório; o público e suas ambigüidades; História Pública: o museu e a Academia