| 1. |
- Bertran, Oscar, et al.
(författare)
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Modeling Nanosized Single Molecule Objects: Dendronized Polymers Adsorbed onto Mica
- 2015
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 119:7, s. 3746-3753
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Tidskriftsartikel (refereegranskat)abstract
- We attempt to provide direct evidence for the suggested behavior of dendronized polymers as molecular objects (i.e., single shape persistent macromolecules). For this purpose, the microscopic structure of dendronized polymers adsorbed onto mica has been investigated using atomistic molecular dynamics simulations. We find that the shape of the second to fourth generation dendronized polymers is basically kept upon adsorption due to substantial backfolding within their interior. The fluctuation strength of the polymer backbones, which is seen to decrease with increasing generation, also indicates that these individual macromolecules exhibit molecular object behavior in the nanosize range.
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| 2. |
- Breznau, Nate, et al.
(författare)
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Observing many researchers using the same data and hypothesis reveals a hidden universe of uncertainty
- 2022
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 119:44
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Tidskriftsartikel (refereegranskat)abstract
- This study explores how researchers analytical choices affect the reliability of scientific findings. Most discussions of reliability problems in science focus on systematic biases. We broaden the lens to emphasize the idiosyncrasy of conscious and unconscious decisions that researchers make during data analysis. We coordinated 161 researchers in 73 research teams and observed their research decisions as they used the same data to independently test the same prominent social science hypothesis: that greater immigration reduces support for social policies among the public. In this typical case of social science research, research teams reported both widely diverging numerical findings and substantive conclusions despite identical start conditions. Researchers expertise, prior beliefs, and expectations barely predict the wide variation in research outcomes. More than 95% of the total variance in numerical results remains unexplained even after qualitative coding of all identifiable decisions in each teams workflow. This reveals a universe of uncertainty that remains hidden when considering a single study in isolation. The idiosyncratic nature of how researchers results and conclusions varied is a previously underappreciated explanation for why many scientific hypotheses remain contested. These results call for greater epistemic humility and clarity in reporting scientific findings.
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| 3. |
- Schlueter, A. Dieter, et al.
(författare)
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Dendronized Polymers: Molecular Objects between Conventional Linear Polymers and Colloidal Particles
- 2014
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Ingår i: ACS Macro Letters. - : American Chemical Society (ACS). - 2161-1653. ; 3:10, s. 991-998
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Tidskriftsartikel (refereegranskat)abstract
- The term molecular object (MO) is introduced to describe single, shape persistent macromolecules that retain their form and mesoscopic dimensions irrespective of solvent quality and adsorption onto a surface. The concept is illustrated with results concerning homologous series of dendronized polymers (DP). In particular, we discuss imaging experiments quantifying deformation upon adsorption, defect characterization, and atomistic molecular dynamics simulations of DP structure. We argue that MOs such as high generation DP, with their large dimensions and high internal density, provide an opportunity to address fundamental questions regarding the onset of bulk-like behavior in single molecules. Illustrative examples of such questions concern the smallest MO exhibiting a glass transition, glassy behavior or a constant bulk density. The characteristics of DP MO are highlighted by comparison to polymer beads, polymeric micelles, globular proteins, and carbon nanotubes. We discuss future research directions and speculate on possibilities involving multiarmed and toroid DP and the effect of DP on friction and rheology, as well as their utilization for nanoconstruction.
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