Views of community assembly have traditionally been based on the contrasting perspectives of the deterministic niche paradigm and stochastic neutral models. This study sought to determine if we could ...use empirical interventions conceived from a niche and neutral perspective to change the diversity and evenness of the microbial community within a reactor treating wastewater and to see if there was any associated change in the removal of endocrine disrupting compounds (EDCs). The systematic removal of EDCs and micropollutants from biological treatment systems is a major challenge for environmental engineers. We manipulated pairs of bioreactors in an experiment in which "niche" (temporal variation in resource concentration and resource complexity) and "neutral" (community size and immigration) attributes were changed and the effect on the detectable diversity and the removal of steroidal estrogens was evaluated. The effects of manipulations on diversity suggested that both niche and neutral processes are important in community assembly. We found that temporal variation in environmental conditions increased diversity but resource complexity did not. Larger communities had greater diversity but attempting to increase immigration by adding soil had the opposite effect. The effects of the manipulations on EDC removal efficiency were complex. Decreases in diversity, which were associated with a decrease in evenness, were associated with an increase in EDC removal. A simple generalized neutral model (calibrated with parameters typical of wastewater treatment plants) showed that decreases in diversity should lead to the increase in abundance of some ostensibly taxa rare. We conclude that neither niche and neutral perspectives nor the effect of diversity on putative rare functions can be properly understood by naïve qualitative observations. Instead, the relative importance of the key microbial mechanisms must be determined and, ideally, expressed mathematically.
The use of solvent annealing to control the microdomain orientation and long-range ordering in poly(isoprene-
b-
d,
l-lactide) thin films was investigated using scanning force microscopy and grazing ...incidence small angle X-ray scattering (GISAXS). Benzene and chloroform were used as annealing solvents. Both were found to improve the long-range order in the films. Additionally, at high concentrations of chloroform in the film, a perpendicular orientation of cylinders was observed where the solvent was able to mediate interfacial interactions sufficiently to prevent a preferential segregation of one of the blocks to the surface. In situ GISAXS measurements made during solvent swelling and evaporation allowed an examination of the film morphology over a wide range of solvent concentrations providing a efficient route to optimize conditions for morphology control by solvent annealing.
The effect of a faceted surface geometry on controlling the direction of well‐defined line patterns of block copolymer (BCP) microdomains over macroscopic areas is reported. Facets with asymmetric ...base angles can control the direction of BCP microdomains oriented either parallel or perpendicular to the facets depending on BCP film thickness.
The ordering processes of PS-
b
-P2VP block copolymer thin films with different processing histories were studied during solvent vapor annealing by in situ grazing incidence small-angle X-ray ...scattering (GISAXS). We compared cylinder-forming PS-
b
-P2VP thin films with 34 kg/mol molecular weight that were prepared in three different ways: spin coating, spin coating and subsequent solvent vapor annealing where the solvent vapor was removed instantaneously, and spin coating and subsequent solvent vapor annealing where the solvent vapor was removed slowly. Block copolymer thin films retained the morphology resulting from the different “processing histories” at smaller swelling ratios. This processing history was erased when the samples reached a higher swelling ratio (~1.4). After the solvent was slowly removed from the swollen film, the surface morphology was characterized by ex situ AFM. All samples showed the same morphology after solvent annealing regardless of the initial morphology, indicating the morphology of solvent annealed samples is determined by the polymer concentration in the swollen film and the solvent vapor removal rate, but not the processing history.
Organic solar cells (OSCs) with a fused-ring dye, ITIC, and fullerene derivative PC 71 BM as the acceptor materials were fabricated. Compared to PC 71 BM-based cells, which reach a power conversion ...efficiency of 6.91%, the ITIC device shows a significantly higher power conversion efficiency (9.20%). The broader absorption range of ITIC helps to improve the short-circuit current density, which leads to better device efficiency. Electrical characterization, including electrical simulations and impedance analysis, was performed to investigate the physical processes in these OSCs. The results suggest that the charge-recombination loss in the non-fullerene device is even higher than that in PC 71 BM cells. Morphological analysis reveals that a poor phase-separation in the photoactive layer is responsible for the large recombination loss. Our results indicate that fused-ring acceptor materials are promising candidates for high-efficiency OSCs. Furthermore, if recombination loss could be suppressed effectively, the energy conversion efficiency of non-fullerene organic solar cells can be even higher.
The jamming of nanoparticle surfactants (NPSs) at liquid–liquid interface imparts attractive properties to the interfacial assemblies and enables the structuring of liquids. Herein, we report ...photoresponsive supramolecular microcapsules with jammed NPS assemblies at the oil‐water interface, taking advantage of host–guest molecular recognition. The permeability of the colloidal membrane can be effectively manipulated by switching the NPSs from a jammed state to an unjammed state with a photo trigger, leading to a controlled molecular diffusion and release, affording a versatile platform for the construction of next generation smart microcapsule systems.
By taking advantage of host–guest molecular recognition at the oil‐water interface, photoresponsive interfacial assemblies with jammed nanoparticle surfactants are present. The permeability of the colloidal membrane can be effectively manipulated by switching the nanoparticle surfactants from a jammed state to an unjammed state with a photo trigger, leading to a controlled molecular diffusion and release, affording a versatile platform for the construction of next generation smart interfacial systems.
Display omitted
Colloid science has classically concerned itself with the investigation of the properties of dispersed phases in a bulk medium. This has led to the development of a rich amount of ...chemistry, physics, and engineering that have facilitated the evolution and maturation of this field. One of the many developments made over the last 30 years is the introduction of particles that are heterogeneous in chemistry and shape. These heterogeneities can introduce behaviors that are not achievable in homogeneous systems and that are specific to the type and class of nonuniformity. This has led to the development of numerous technologies, two of which are Janus micromotors and solid surfactants. This review aims to familiarize the reader with the field of heterogeneous particles. We begin with an overview of various synthetic methods to produce colloidal particles that are heterogeneous in chemistry and shape. We then discuss their use as solid surfactants and autonomous micromotors. We then close by summarizing and providing a future perspective on the field.
The synthesis of high‐aspect‐ratio (AR) CdSe (NRs) nanorods and their ordered assembly over large areas are reported. Long‐range ordering of hexagonal arrays of high‐AR NRs is achieved by a ...combination of controlled solvent evaporation and the use of an applied electric field. Vertically oriented assemblies of CdSe NRs functionalized with oligo‐ and polythiophene are also obtained. Aligned and oriented polythiophene CdSe NRs have potential applications in organic–inorganic hybrid bulk‐heterojunction photovoltaic devices.
The long‐range vertical ordering of high‐aspect‐ratio CdSe nanorods is described. Multiple layers of close‐packed hexagonal nanorod arrays are achieved through the application of an electric field during nanorod assembly. Vertically oriented CdSe nanorods, surface‐functionalized with polythiophene, hold potential for improving charge transport in hybrid bulk heterojunction solar cells.
Nanoparticles have useful properties, but it is often important that they only start working after they are placed in a desired location. The encapsulation of nanoparticles allows their function to ...be preserved until they are released at a specific time or location, and this has been exploited in the development of self-healing materials and in applications such as drug delivery. Encapsulation has also been used to stabilize and control the release of substances, including flavours, fragrances and pesticides. We recently proposed a new technique for the repair of surfaces called 'repair-and-go'. In this approach, a flexible microcapsule filled with a solution of nanoparticles rolls across a surface that has been damaged, stopping to repair any defects it encounters by releasing nanoparticles into them, then moving on to the next defect. Here, we experimentally demonstrate the repair-and-go approach using droplets of oil that are stabilized with a polymer surfactant and contain CdSe nanoparticles. We show that these microcapsules can find the cracks on a surface and selectively deliver the nanoparticle contents into the crack, before moving on to find the next crack. Although the microcapsules are too large to enter the cracks, their flexible walls allow them to probe and adhere temporarily to the interior of the cracks. The release of nanoparticles is made possible by the thin microcapsule wall (comparable to the diameter of the nanoparticles) and by the favourable (hydrophobic-hydrophobic) interactions between the nanoparticle and the cracked surface.
The fabrication process for 5 Tb/in2 bit patterns using solvent‐assisted directed self‐assembly is investigated. The N‐methyl‐2‐pyrrolidone solvent vapor‐annealing method was used to achieve good ...long‐range lateral ordering of low‐molecular‐weight polystyrene‐block‐polydimethylsiloxane with a lattice spacing of 11 nm on flat Si substrates, PS modified substrates and lithographically patterned substrates, respectively.
PDF
