1,721,223 research outputs found
Ordered microdomain morphologies in saccharide-containing block copolymers
No full textHybrid block copolymers containing both oligosaccharide and synthetic polymer components have attracted much interest in recent years as sustainable material alternatives. In particular block copolymers containing saccharides are capable of microphase separation at small molecular weights, leading to the formation of ordered morphologies with sub-10 nm feature sizes. We synthesize ABA-type triblock copolymers containing polystyrene as the synthetic mid-block and either trisaccharide maltotriose (MT) or disaccharide maltose (Mal) as the end blocks. The polymers are prepared by a combination of atom transfer radical polymerization (ATRP) and click reaction, and their bulk morphologies are examined by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The MT-containing triblocks are found to form well-ordered domain structures with sub-10 nm periodicity, and morphology transition from cylinders to spheres to disordered spheres is observed with decreasing saccharide weight fraction. The Mal-containing triblocks also show microphase separation. However, the observed domain morphologies lack regular packing due to the close proximity of polymer glass transition temperature and order-disorder transition temperature. The saccharide components of the block copolymers are also found to undergo different degrees of dehydration when exposed to high temperatures. The dehydration reaction leads to the molecular change of the triblocks to form pentablock copolymers, resulting in the emergence of less ordered secondary morphologies in an irreversible manner
Making the invisible visible: Understanding complex healthcare service processes for assessment
No full textEarlier studies have reported that there is a huge gap between customers and service providers in terms of the perceived quality of the service experience. This research addresses the delivery gap between service providers and service customers by offering service providers tools and strategies that enable them to better understand the complexity of their services.
This research contributes to the field of health service research through the identification of the key components of services in healthcare and the development of the service process learning cycle model, which improves the understanding of complex service processes in healthcare. This study also contributes to the service design field, as it includes a discussion of the communication gaps in service design, and an exploration of how a visual language and the artefacts generated by the language can contribute to service providers’ understanding of complex services in empirical settings
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Decoding the evolution and dynamics of semicrystalline block copolymer assembly via liquid-phase transmission electron microscopy
No full textNature utilizes self-assembly to form complex, functional structures, inspiring advanced materials design. Polymer crystallization drives assemblies with both ordered and disordered regions. Crystallization-driven assembly of BCPs enables unique hierarchical nanostructures with enhanced colloidal stability and directionality, applicable from optoelectronics to biomedicine. However, mechanisms governing morphological transitions remain poorly understood due to complex microphase separation and competitive crystallization. Using liquid-phase transmission electron microscopy, we visualize the spontaneous assembly of semicrystalline amphiphilic BCPs. We observe structural transformations from unimers to spherical, cylindrical, toroidal micelles, and vesicles by varying constituent block ratios. Image segmentation overcomes low contrast of aqueous assemblies, enabling motion tracking. Nanostructures exhibit structural evolution driven by long-range hydrophobic interactions from formed elemental micelles undergoing anomalous diffusion. Notably, toroid formation follows a distinct pathway compared with conventional BCPs due to semicrystalline BCPs' preference for low curvature at the core-corona interface. Insights into assembly dynamics via real-time imaging provide strategies for controlling complex hierarchical structures.
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
In vivo p53 function is indispensable for DNA damage-induced apoptotic signaling in Drosophila
No full textp53 is a representative tumor suppressor whose dysfunction is a major cause of human cancer syndrome. Here we isolated flies lacking Dmp53, which encodes the single Drosophila orthologue of mammalian p53 family. Dmp53 null mutants well developed into adults, only displaying mild defects in longevity and fertility. However, genomic stability and viability of Dmp53 mutants dramatically decreased upon ionizing irradiation. Moreover, mutating Dmp53 abolished irradiation-induced apoptosis and reaper induction. These results indicate that Dmp53 is a central component of DNA damage-dependent apoptotic signaling. (C) 2003 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.This research was supported by a National Creative Research Initiatives grant from the Korean Ministry of Science and Technology/KOSEF
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
A human-machine collaborative approach measures economic development using satellite imagery
No full textMachine learning approaches using satellite imagery are providing accessible ways to infer socioeconomic measures without visiting a region. However, many algorithms require integration of ground-truth data, while regional data are scarce or even absent in many countries. Here we present our human-machine collaborative model which predicts grid-level economic development using publicly available satellite imagery and lightweight subjective ranking annotation without any ground data. We applied the model to North Korea and produced fine-grained predictions of economic development for the nation where data is not readily available. Our model suggests substantial development in the country’s capital and areas with state-led development projects in recent years. We showed the broad applicability of our model by examining five of the least developed countries in Asia, covering 400,000 grids. Our method can both yield highly granular economic information on hard-to-visit and low-resource regions and can potentially guide sustainable development programs. © 2023, The Author(s).11Nsciescopu
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