22 research outputs found
The linguistic construction of world : an example of visual analysis and methodological challenges
In this article we discuss common approaches to using data visualizations within the field of digital humanities. We argue that by assigning equal importance to the development, as well as the usage of a visualization framework, researchers can question dogmatic âbest-practiceâ norms for data visualizations which may prevent them from developing visualizations that can be used to find emergent phenomena within the underlying data. We then focus on the question, how visualizations re-constitute language by using diagrammatic operations. Also of big importance working with digital visualizations is the technological background influencing the tools built with and the effect on the interpretation of the data. As an example approach, we present our visualization framework called âgeocollocationsâ which can be used as an interactive tool to detect words that typically collocate with toponyms based on the data of various text corpora
Nanocomposites of high-density polyethylene with amorphous calcium phosphate: in vitro biomineralization and cytocompatibility of human mesenchymal stem cells
Polyethylene is widely used as a component of implants in medicine. Composites made of high-density polyethylene (HDPE) containing different amounts of amorphous calcium phosphate nanoparticles were investigated concerning their in vitro biomedical performance. The nanoparticles were produced by flame spray synthesis and extruded with HDPE, the latter complying with Food and Drug Administration regulations. Mechanical properties such as Young's modulus and contact angle as well as in vitro biomineralization of the nanocomposites hot-pressed into thin films were evaluated. The deposition of a hydroxyapatite layer occurred upon immersion in simulated body fluid. Additionally, a cell culture study with human mesenchymal stem cells for six weeks allowed a primary assessment of the cytocompatibility. Viability assays (alamarBlue and lactate dehydrogenase detection) proved the absence of cytotoxic effects of the scaffolds. Microscopic images after hematoxylin and eosin staining confirmed typical growth and morphology. A preliminary experiment analyzed the alkaline phosphatase activity after two weeks. These findings motivate further investigations on bioactive HDPE in bone tissue engineering
Large-Scale Synthesis of PbSâTiO<sub>2</sub> Heterojunction Nanoparticles in a Single Step for Solar Cell Application
The demand for low cost solar energy technology calls
for manufacturing processes using economic liquid- or gas-phase synthesis
of the corresponding materials. In this regard, manufacturing of quantum
dot-sensitized solar cells is particularly complicated through multiple-step
preparations. Material pairs such as TiO<sub>2</sub>âPbS heterojunctions
have shown high absorption of visible light and good electron transfer
properties. However, traditional solution processing requires extensive
surface functionalization or the use of surfactants to obtain well-defined
films. Such surfactants, unfortunately, often lower electron hopping/tunneling
in the system (surfactants are usually insulators) and therefore have
to be removed or exchanged before completing device fabrication. Similarly,
the so far presented processes to deposit PbS directly on TiO<sub>2</sub> are very time consuming. In this paper, we present a single-step,
large-scale, operable process to synthesize PbSâTiO<sub>2</sub> heterojunction particles by aerosol synthesis using reducing flame
spray pyrolysis. Nanopowders with different lead sulfide to titanium
dioxide ratios were produced and characterized. Thermodynamic equilibrium
calculations of the gaseous environment during the combustion process
show that the process is robust with regard to usual process changes
or fluctuations. We further showed how this approach allowed us to
vary the structure and size of the PbSâTiO<sub>2</sub> heterojunction
particles, as long as an excess of sulfur species (S/Pb = 2.5) was
applied during processing
Electrical Resistivity of Assembled Transparent Inorganic Oxide Nanoparticle Thin Layers: Influence of Silica, Insulating Impurities, and Surfactant Layer Thickness
The electrical properties of transparent, conductive
layers prepared
from nanoparticle dispersions of doped oxides are highly sensitive
to impurities. Production of cost-effective thin conducting films
for consumer electronics often employs wet processing such as spin
and/or dip coating of surfactant-stabilized nanoparticle dispersions.
This inherently results in entrainment of organic and inorganic impurities
into the conducting layer leading to largely varying electrical conductivity.
Therefore, this study provides a systematic investigation on the effect
of insulating surfactants, small organic molecules and silica in terms
of pressure dependent electrical resistivity as a result of different
core/shell structures (layer thickness). Application of high temperature
flame synthesis gives access to antimony-doped tin oxide (ATO) nanoparticles
with high purity. This well-defined starting material was then subjected
to representative film preparation processes using organic additives.
In addition ATO nanoparticles were prepared with a homogeneous inorganic
silica layer (silica layer thickness from 0.7 to 2 nm). Testing both
organic and inorganic shell materials for the electronic transport
through the nanoparticle composite allowed a systematic study on the
influence of surface adsorbates (e.g., organic, insulating materials
on the conducting nanoparticleâs surface) in comparison to
well-known insulators such as silica. Insulating impurities or shells
revealed a dominant influence of a tunneling effect on the overall
layer resistance. Mechanical relaxation phenomena were found for 2
nm insulating shells for both large polymer surfactants and (inorganic)
SiO<sub>2</sub> shells
Fictive motion extraction and classification
Fictive motion (e.g. âThe highway runs along the coastâ) is a pervasive phenomenon in language that can imply both a staticand a moving observer. In a corpus of alpine narratives, it is used in three types of spatial descriptions: conveying the actual motion of the observer, describing a vista and communicating encyclopaedic spatial knowledge. This study takes a knowledge-based approach to develop rules for automated extraction and classification of these types based on an annotated corpus of fictive motion instances. In particular, we identify the differences in the set of concepts involved into the production of the three types of descriptions, followed by their linguistic operationalization. Based on that, we build a set of rules that classify fictive motion with an overall precision of 0.87 and recall of 0.71. The article highlights the importance of examining spatially rich, naturally occurring corpora for the lines of work dealing with the automated interpretation of spatial information in texts, as well as, more broadly, investigation of spatial language involved into various types of spatial discourse