Enhancing the Yield Stress in Liquid Polydimethylsiloxane to Allow Its 3D Printing: Hydrogels as Removable Fillers

For manufacturing parts of very soft materials by liquid deposition modeling (e.g., to mimic living soft tissues), formulations of 3D-printable polydimethylsiloxane have been developed, with the aim of increasing the yield stress of the liquid and reducing the final mechanical modulus. In the present work, suspensions of solid-like hydrogel particles, which are easily 3D-printable, are prepared in order to generate yield stress, and the suspended phase is removed after manufacturing by taking advantage of the thermo-reversibility of the hydrogel behavior, resulting in porosity, which reduces the final rigidity. The reported approach is even more efficient than a previous approach based on emulsion formulations.     

Structure and dynamics of scientific networks. Part I: Fundamentals of the quantitative model of translation

The fundamentals have been developed for a quantitative theory on the structure and dynamics of scientific networks. These fundamentals were conceived through a new vision of translation, defined mathematically as the derivative or gradient of the quality of the actors as a function of the coordinates for the space in which they perform. If we begin with the existence of a translation barrier, or an obstacle that must be overcome by the actors in order to translate, and if we accept the Maxwell-Boltzmann distribution as representative of the translating capacity of the actors, it becomes possible to demonstrate the known principle of “success breeds success.” We also propose two types of elemental translation: those which are irreverisble and those which are in equilibrium. In addition, we introduce the principle of composition, which enables, from elemental translations, the quantification of more complex ones.     

A scientometric approach to autism based on translation sociology

We advance the following hypothesis with respect to the construction of scientific knowledge: a) a scientific article may be seen as bringing together differing knowledge networks within the same experimental context; b) the researcher attempts to prove the existence of objective links within this context. This process allows the researcher to link or associate his own subjective proposals to those that are verifiably objective relationships for all researchers. Researchers consolidate the relationships put forward by others accordingly. There is a statistic method which makes it possible to demonstrate these dynamics, i.e., co-word analysis. This method, applied to articles on autism, has provided results that support this hypothesis. The methods brought to bear by the majority of researchers follow these general dynamics.     

Policy and the mapping of scientific change: A co-word analysis of research into environmental acidification

This paper describes recent developments in the co-word method and illustrates, for the case of acid rain research, the way in which the method can be used to detect (a) the themes of research to be found in a given area of science, (b) the relationships between those themes, (c) the extent to which they are central to the area in question and (d) the degree to which they are internally structured. It is also suggested that the method may be used to draw comparative research profiles for different countries. Though the data used are only preliminiary, it is argued that the method has now been developed to the point where its results are both quite robust and easily assimilable. It is, accordingly, now an appropriate tool for policy analysis.     

Major chromosomal rearrangements induced by T-DNA transformation in Arabidopsis

We show that major chromosomal rearrangements can occur upon T-DNA transformation of Arabidopsis thaliana. In the ACL4 line, two T-DNA insertion loci were found; one is a tandem T-DNA insert in a head-to-head orientation, and the other is a truncated insert with only the left part of the T-region. The four flanking DNA regions were isolated and located on the Arabidopsis chromosomes; for both inserts, one side of the T-DNA maps to chromosome 2, whereas the other side maps to chromosome 3. Both chromosome 3 flanking regions map to the same location, despite a 1.4-kb deletion at this point, whereas chromosome 2 flanking regions are located 40 cM apart on the bottom arm of chromosome 2. These results strongly suggest a reciprocal translocation between chromosomes 2 and 3, with the breakpoints located at the T-DNA insertion sites. The interchanged fragments roughly correspond to the 20-cM distal ends of both chromosomes. Moreover, a large inversion, spanning 40 cM on the genetic map, occurs on the bottom arm of chromosome 2. This was confirmed by genetic analyses that demonstrated a strong reduction of recombination in the inverted region. Models for T-DNA integration and the consequences for T-DNA tagging are discussed in light of these results.     

The use of patent titles for identifying the topics of invention and forecasting trends

Co-word analysis applied to patents through WPIL normalized title words appears to give a useful picture of a given field: we obtain both qualitative (themes) and quantitative information (weight of themes). It also gives information about the strategic aspects of the themes. Furthermore, in some cases, it is an indication of the future of certain themes that may help forecasting and management studies. Finally, it provides information about what could be a real technology growth process, in relation to the so-called translation model used in co-word analysis.     

The use of review articles in the analysis of a research area

Review articles in the field of polymer science in the seventies are analyzed in order to check their usefulness in describing at a very low cost the development or the state of the art of a field. Results are compared with those obtained through a quantitative study of scientific articles published at the same time in the field. Review articles can be regarded as defining a research programme attempting to link together two networks: polymer properties—as being desirable from market considerations—and polymer structure—as being analyzable by means of academic science, through three kinds of translation strategies. If we thus define a research programme in terms of the mobilization of networks, it is possible to say of review articles that they provide a good representation of the development of networks of problems whose evolution they sketch.We are sad to inform our scientometric colleagues that this is F. Bastide's last contribution as she died in the autum of 1988.     

Performance of a rotating aperture for spinning and orienting objects in optical tweezers

Abstract

The spinning of asymmetric objects trapped within optical tweezers that have a rotating rectangular aperture inserted into the trapping laser beam is characterized. The measured maximum rotation rates of various asymmetric micron-sized objects are in agreement with a linear dependence on laser power. Maximum rotation rates of up to 0.2 Hz per mW of laser power suggest that rotation rates in the region of 10–20 Hz should be readily achievable in commercially available tweezers that have been modified by the inclusion of a rotating rectangular aperture. In addition, the possibility to alter the orientation of the aperture allows convenient control over the orientation of tweezed objects.     

Scientific innovation in bibliographical databases: A comparative study of the science citation index and the pascal database

This study compares information obtained from the INIST/CNRS bibliographical database PASCAL with that found in theAtlas of Science published by ISI. The goal of the comparison was to contribute, to a better understanding of how databases can be used to carry out fine-grained studies of social and cognitive factors which affect the definition of a scientific research program. The program studied concern the development of research on brushborder cell membranes.