1,721,400 research outputs found
Molecular and structural basis of low interfacial energy of complex coacervates in water
No full textComplex coacervate refers to a phase-separated fluid, typically of two oppositely charged polyelectrolytes in solution, representing a complex fluid system that has been shown to be of essential interest to biological systems, as well as for soft materials processing owing to the expectation of superior underwater coating or adhesion properties. The significance and interest in complex coacervate fluids critically rely on its low interfacial tension with respect to water that, in turn, facilitates the wetting of macromolecular or material surfaces under aqueous conditions, provided there is attractive interaction between the polyelectrolyte constituents and the surface. However, the molecular and structural bases of these properties remain unclear. Recent studies propose that the formation of water filled and bifluidic sponge-like nanostructured network, driven by the tuning of electrostatic interactions between the polyelectrolyte constituents or their complexes may be a common feature of complex coacervate fluids that display low fluid viscosity and low interfacial tension, but more studies are needed to verify the generality of these observations. In this review, we summarize representative studies of interfacial tension and ultrastructures of complex coacervate fluids. We highlight that a consensus property of the complex coacervate fluid is the observation of high or even bulk-like water dynamics within the dense complex coacervate phase that is consistent with a low cohesive energy fluid. Our own studies on this subject are enabled by the application of magnetic resonance relaxometry methods relying on spin labels tethered to polyelectrolyte constituents or added as spin labeled probe molecules that partition into the dense versus the equilibrium coacervate phase, permitting the extraction of information on local polymer dynamics, polymer packing and local water dynamics. We conclude with a snapshot of our current perspective on the molecular and structural bases of the low interfacial tension of complex coacervate fluids. (C) 2016 Elsevier B.V. All rights reserved.1194sciescopu
Aesthetically improved and efficient tannin–metal chelates for the treatment of dentinal hypersensitivity
No full textDentinal hypersensitivity is an acute transient pain caused by the exposition of the dentinal tubules. The exposed tubules not only cause hypersensitivity but also cause the yellow coloration of the teeth due to their dominance in teeth coloration. An occlusion of the open dentinal tubules by the in situ biomineralization of hydroxyapatite (HAp) is so far the most effective method to alleviate the dentinal hypersensitivity. In recent years, several remineralization strategies, employing various substrates, have been studied for the treatment of dentinal hypersensitivity. However, aesthetically ideal solutions that include the tooth whitening aspect are poorly studied alongside with the tubular occlusion. Herein, the aesthetical improvement along with significant bioremineralization of the HAp crystals for the treatment of dentinal hypersensitivity was examined after a tannin (TA)-metal (ions and oxides) chelates mediated mineralization. Thus, demineralized human molar disks were treated with tannin-based chelates (TA-M). Briefly, TA-M denotes TA combined with 5 different daily intake metal ions and metal oxides, such as Sr(NO3)(2), Fe2O3, TiO2, CaCl2, VCl3, and a non-metal oxide SiO2 in separate experiments. The samples were coated in the TA-M solution for 4 min followed by immersion in an artificial saliva for 7 days. Biomineralized HAp crystals were well-characterized by various analytical techniques. Among these, TASr( NO3)(2) and TA-TiO2 exhibited the most promising results, as they occluded ca. 79% and 68% of the dentinal tubules, respectively, with brighter color changes after the treatment. This desensitizing solution camouflaged the exposed dentin by its whitening effect using biocompatible Sr and Ti oxides, which may be potential for developing facile 'at-home' aesthetically effective dental desensitizer solution.1120Ysciescopu
The slip agents oleamide and erucamide reduce biofouling by marine benthic organisms (diatoms, biofilms and abalones)
No full text110scopu
Cation-pi Interactions and Their Contribution to Mussel Underwater Adhesion Studied Using a Surface Forces Apparatus: A Mini-Review
No full textMussel underwater adhesion is a model phenomenon important for the understanding of broader biological adhesion and the development of biomimetic wet adhesives. The catechol moiety of 3,4-dihydroxyphenyl-L-alanine (DOPA) is known to be actively involved in the mechanism of mussel underwater adhesion; however, other underwater adhesion mechanisms are also crucial. The surface forces apparatus (SFA) has often been used to explore the contributions of other mechanisms to mussel underwater adhesion; e.g., recent SFA-based nanomechanical studies have revealed that cation-pi interactions, one of the strongest intermolecular interactions in water, are the pivotal interactions of adhesive proteins involved in underwater mussel adhesion. This mini-review surveys recent research on cation-pi- interactions and their contributions to strong mussel underwater adhesion, shedding light on some biological processes and facilitating the development of biomedical adhesives.11Nsciescopu
Effects of calcification inhibitors on the viability of the coralline algae Lithophyllum yessoense and Corallina pilulifera
No full textCoralline algae, the algal whitening phenomenon-causing seaweeds, are characterized by calcareous deposits in the cell wall. The viability of the coralline algae Lithophyllum yessoense and Corallina pilulifera was quantitated using a triphenyltetrazolium chloride assay and eight calcification inhibitors. Among these inhibitors, ferric citrate showed the strongest inhibition of coralline algae viability. The concentrations of ferric citrate conferring 50% inhibition were 1.7 and 3.8 mM for L. yessoense and C. pilulifera, respectively. Thus, at a specific concentration and in a localized area, ferric citrate may be used to prevent the blooming of coralline algae. © 2014 The Korean Society of Fisheries and Aquatic Science.11Nscopu
Stabilizing Coacervate by Microfluidic Engulfment Induced by Controlled Interfacial Energy
No full textLow interfacial energy, an intrinsic property of complex coacervate, enables the complex coacervate to easily encapsulate desired cargo substances, making it widely used in encapsulation applications. Despite this advantage, the low interfacial energy of the complex coacervate makes it unstable against mechanical mixing, and changes in pH and salt concentration. Hence, a chemical cross-linker is usually added to enhance the stability of the complex coacervate at the expense of sacrificing all intrinsic properties of the coacervate, including phase transition of the coacervate from liquid to solid. In this study, we observed an abrupt increase in the interfacial energy of the coacervate phase in mineral oil. By controlling the interfacial energy of the coacervate phase using a microfluidic device, we successfully created double engulfed PEG-diacrylate (PEGDA) coacervate microparticles, named DEPOT, in which the coacervate is engulfed in a cross-linked PEGDA shell. The engulfed coacervate remained as a liquid phase, retained its original low interfacial energy property to encapsulate the desired cargo substances, and infiltrated into the target site by a simple solvent exchange from oil to water.11Nsciescopu
Antifouling effects of the periostracum on algal spore settlement in the mussel Mytilus edulis
Full text linkAbstract In nature, marine mussels (Mytilus edulis) suffer less fouling colonization on the newly formed sides of their shells. Using settlement assays with algal spores of Porphyra suborbiculata, we determined that spore attachment and germination on the periostracum decreased to 36.8 and 3.3 %, respectively. Additionally, the spore settlement was considerably diminished by periostracum dichloromethane extracts containing 19 % oleamide, a major antifouling compound. A scanning electron micrograph of the surface revealed a regular ripple structure with approximately 1.4 μm between ripples. Based on these results, mussel periostraca or their associated biomimetic materials may become environmentally friendly, antifouling agents for preventing the settlement of soft foulants
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
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