Though amphiphiles are ubiquitously used for altering interfaces, interfacial reorganization processes are in many cases obscure. For example, adsorption of micelles to liquid–liquid interfaces is ...often accompanied by rapid reorganizations toward monolayers. Then, the involved time scales are too short to be followed accurately. A block copolymer system, which comprises poly(ethylene oxide)110‐b‐poly{2‐(methacryloyloxy)ethyldiisopropylmethylammonium chloride}170 (i.e., PEO110‐b‐qPDPAEMA170 with quaternized poly(diisopropylaminoethyl methacrylate)) is presented. Its reorganization kinetics at the water/n‐decane interface is slowed down by electrostatic interactions with ferricyanide (Fe(CN)63–). This deceleration allows an observation of the restructuring of the adsorbed micelles not only by tracing the interfacial pressure, but also by analyzing the interfacial rheology and structure with help of atomic force microscopy. The observed micellar flattening and subsequent merging toward a physically interconnected monolayer lead to a viscoelastic interface well detectable by interfacial shear rheology (ISR). Furthermore, the “gelled” interface is redox‐active, enabling a return to purely viscous interfaces and hence a manipulation of the rheological properties by redox reactions. Additionally, interfacial Prussian blue formation stiffens the interface. Such manipulation and in‐depth knowledge of the rheology of complex interfaces can be beneficial for the development of emulsion formulations in industry or medicine, where colloidal stability or adapted permeability is crucial.
Pathways are presented for the reshaping of micelles at interfaces, reminiscent of an autonomous kneading of dough. The flattening and merging of the polymer‐based micelles lead to a thin viscoelastic gel monolayer. By adding further ingredients to the interfacial “pizza,” the viscoelastic properties of the film can be changed, either leading to a stiffening or to a disappearance of elasticity.
The performance of metal-organic frameworks in gas chromatographic separation investigations has been widely study in recent years. However, to use chromatographic methods to determine materials ...properties of metal-organic frameworks instead of using them just for analyte separations is a field still largely unexplored. The presented study has been conducted to quantify the systematic changes in the interaction of a series of related unbranched aliphatic analytes (C2-C10) with HKUST-1 as the stationary phase not only to obtain information about the MOF analyte interaction strength but also to gain materials parameters characterizing the MOF system, like its response to non-specific interactions. Thermodynamic as well as by kinetic parameters governing the adsorption process were determined using various chromatographic evaluation techniques. The method of inverse chromatography was used to derive the generic susceptibility of HKUST-1 to aliphatic methylene groups and to determine interfacial energy contributions of the intrinsic surface of the porous material.
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•HKUST-1 was used for gas chromatographic separations of n-alkanes.•Enthalpies and entropies, describing the adsorption on HKUST-1, were determined.•Kinetic data, such as diffusion coefficients, were obtained by the Golay analysis.•The generic CH2-group contribution to the free energy of adsorption on HKUST-1 was calculated.•An evaluation of interfacial energy contributions of the intrinsic surface was conducted.
In the last years, the generation of multifunctional coatings has been moved into the focus of interface modifications to expand the spectrum of material applications and to introduce new smart ...properties. Herein a promising multifunctional and universally usable coating with simultaneous antifouling, easy‐to‐clean, and anti‐fog functionality is presented based on smart polymer films consisting of copolymers with 2‐methacryloyloxyethyl phosphorylcholine (MPC), realizing the function of the film and photoreactive 4‐benzophenyl methacrylate (BPO), which is responsible for stability and crosslinking. The easy‐to‐clean effect is demonstrated qualitatively and quantitatively by oil droplet detachment experiments. The antifouling behavior against different germs is investigated by cell adhesion experiments. Furthermore the anti‐fog performance is shown by breathing on the surfaces. To study the influence of the different amounts of copolymerized BPO, the grafted films are characterized by atomic force microscopy (AFM), infrared spectroscopy (ATR‐FTIR), as well as contact angle measurements. In situ spectroscopic ellipsometry is performed to investigate the swelling behavior of the thin films as a function of the time of UV‐irradiation. It is found that a degree of swelling of 15 and a water contact angle of less than 12° are the key parameters necessary for the generation of multifunctional coatings.
A multifunctional coating, combining easy‐to‐clean, anti‐fog, and antifouling properties is achieved by preparing thin films of a set of co‐polymers of 2‐methacryloyloxyethyl phosphorylcholine (MPC) and benzophenone (BPO) to study structure–property relationships. The study shows that an exactly balanced ratio between thickness of dry films, degree of swelling, and water contact angle is necessary to create surface coatings with tailored properties.
Declines in animal body sizes are widely reported and likely impact ecological interactions and ecosystem services. For harvested species subject to multiple stressors, limited understanding of the ...causes and consequences of size declines impedes prediction, prevention, and mitigation. We highlight widespread declines in Pacific salmon size based on 60 years of measurements from 12.5 million fish across Alaska, the last largely pristine North American salmon-producing region. Declines in salmon size, primarily resulting from shifting age structure, are associated with climate and competition at sea. Compared to salmon maturing before 1990, the reduced size of adult salmon after 2010 has potentially resulted in substantial losses to ecosystems and people; for Chinook salmon we estimated average per-fish reductions in egg production (-16%), nutrient transport (-28%), fisheries value (-21%), and meals for rural people (-26%). Downsizing of organisms is a global concern, and current trends may pose substantial risks for nature and people.
The microbial infection as a result of biofilm formation is a serious problem in various fields of application in the paper industry including fouling of filters in air conditioning systems, ...wallpaper, medical and food packaging as well as ancient documents. In this study, we document a highly nonfouling surface coating formed by a functional copolymer consisting of 2-methacryloyloxyethyl phosphorylcholine, as a zwitterionic and cell repellent component, and 4-benzophenyl methacrylate, acting as an anchor group for a fast UV-induced persistent covalent attachment on thin cellulose model films deposited on silicon wafers. The grafting process, studied by UV–Vis spectroscopy, is much faster in comparison with common grafting-to techniques. The obtained sustainable and nonleaching surface coatings were analyzed by attenuated total reflectance-Fourier transform infrared spectroscopy, contact angle measurements, spectroscopic in situ ellipsometry, and atomic force microscopy. Incubation of the modified cellulose surfaces with either
Escherichia coli, Bacillus subtilis
or
Saccharomyces cerevisiae
demonstrates that the zwitterionic polymer functionalization has substantial nonfouling capacity against both Gram-negative and Gram-positive bacteria as well as the yeast fungus.
Recently developed MOF surface‐coating techniques, the controlled SBU approach (CSA) for the generation of MOF‐5, and the use of self‐assembled monolayers have been combined to generate a ...wall‐bonded, crosslinked stationary phase for gas chromatographic capillary columns displaying excellent performance in the separation of natural gas components. The chromatographic performance of this new type of column has been compared to the state‐of‐the‐art solution for this separation problem, namely a coated silica column of the porous layer open tubular (PLOT) type. Chromatographic parameters such as separation, resolution, and tailing factors, as well as plate numbers and heights in the case of isothermal operation, have been determined. Kinetic and thermodynamic parameters characterizing the analyte–stationary phase interaction have been determined for various C1–C4 analytes.
Based on special surface preparation techniques using self‐assembled monolayers and the controlled SBU approach (CSA) for the deposition of metal–organic frameworks, MOF‐CSA‐based coatings in capillary columns for gas chromatography have been produced (see graphic, orange trace: MOF‐based, blue trace: commercially available PLOT column).
Hereditary spastic paraplegia (HSP) is a neurodegenerative disorder selectively affecting axons of spinal cord motoneurons. Classical mutations in the most frequent HSP gene SPAST (spastin protein) ...act through haploinsufficiency by abolishing the activity of a C‐terminal ATPase domain or by interfering with expression from the affected allele. N‐terminal missense variants have been suggested to represent rare polymorphisms, to cause unusually mild phenotypes, and to aggravate the effect of a classical mutation. We confirm these associations for p.S44L but do not detect two other variants (p.E43Q; p.P45Q) in HSP patients and controls. We show that neither of several disease mechanisms associated with classical SPAST mutations applies to the N‐terminal variants. Instead, all three alterations enhance the stability of one of two alternative spastin isoforms. Their phenotypic effect may thus not be mediated by haploinsufficiency but by increasing isoform competition for interacting proteins, substrates or oligomerization partners.
How is it possible to remove oily impurities from surfaces with pure water without the use of surfactants? In article number 1901422 by Alexander Münch, Petra Uhlmann, and co‐workers, a new ...functional coating is achieved by preparing thin films of ultra‐hydrophilic and swellable co‐polymers. Due to the formation a highly swollen polymer film in contact with water, the oil droplets cannot interact with the surface anymore and float away.
Knowledge of geographic and temporal scales of adaptive genetic variation is crucial to species conservation, yet understanding of these phenomena, particularly in marine systems, is scant. Until ...recently, the belief has been that because most marine species have highly dispersive or mobile life stages, local adaptation could occur only on broad geographic scales. This view is supported by comparatively low levels of genetic variation among populations as detected by neutral markers. Similarly, the time scale of adaptive divergence has also been assumed to be very long, requiring thousands of generations. Recent studies of a variety of species have challenged these beliefs. First, there is strong evidence of geographically structured local adaptation in physiological and morphological traits. Second, the proportion of quantitative trait variation at the among‐population level (QST) is much higher than it is for neutral markers (FST) and these two metrics of genetic variation are poorly correlated. Third, evidence that selection is a potent evolutionary force capable of sustaining adaptive divergence on contemporary time scales is summarized. The differing spatial and temporal scales of adaptive v. neutral genetic divergence call for a new paradigm in thinking about the relationship between phenogeography (the geography of phenotypic variation) and phylogeography (the geography of lineages) in marine species. The idea that contemporary selective processes can cause fine‐scale spatial and temporal divergence underscores the need for a new emphasis on Darwinian fishery science.