Characterization of biofilm formation in natural water subjected to low-frequency electromagnetic fields

Electromagnetic field (EMF) treatment has proven to be effective against mineral scaling in water systems. Therefore, it should be assessed for the treatment of other deposits such as biofilms. In this study, a commercial device producing low-frequency EMF (1–10 kHz) was applied to a reactor fed with natural water for 45 days. The treatment promoted the concentration of microorganisms in suspension and limited the amount of sessile microorganisms in the biofilm, as determined by the measurement of total DNA, qPCR and microscopy. The structure of the bacterial community was assessed by t-RFLP and pyrosequencing analysis. The results showed that EMF treatment affected both planktonic and sessile community composition. EMFs were responsible for a shift in classes of Proteobacteria during development of the biofilm. It may be speculated that the EMF treatment affected particle solubility and/or microorganism hydration. This study indicated that EMFs modulated biofilm formation in natural water.     

Comparison of laboratory and field testing performance evaluations of siloxane-polyurethane fouling-release marine coatings

A series of eight novel siloxane-polyurethane fouling-release (FR) coatings were assessed for their FR performance in both the laboratory and in the field. Laboratory analysis included adhesion assessments of bacteria, microalgae, macroalgal spores, adult barnacles and pseudobarnacles using high-throughput screening techniques, while field evaluations were conducted in accordance with standardized testing methods at three different ocean testing sites over the course of six-months exposure. The data collected were subjected to statistical analysis in order to identify potential correlations. In general, there was good agreement between the laboratory screening assays and the field assessments, with both regimes clearly distinguishing the siloxane-polyurethane compositions comprising monofunctional poly(dimethyl siloxane) (PDMS) (m-PDMS) as possessing superior, broad-spectrum FR properties compared to those prepared with difunctional PDMS (d-PDMS). Of the seven laboratory screening techniques, the Cellulophaga lytica biofilm retraction and reattached barnacle (Amphibalanus amphitrite) adhesion assays were shown to be the most predictive of broad-spectrum field performance.     

Optical Activity Governed by Local Chiral Structures in Two‐Dimensional Curved Metallic Nanostructures

Chiral nanostructures show macroscopic optical activity. Local optical activity and its handedness are not uniform in the nanostructure, and are spatially distributed depending on the shape of the nanostructure. In this study we fabricated curved chain nanostructures made of gold by connecting linearly two or more arc structures in a two‐dimensional plane. Spatial features of local optical activity in the chain structures were evaluated with near‐field circular dichroism (CD) imaging, and analyzed with the aid of classical electromagnetic simulation. The electromagnetic simulation predicted that local optical activity appears at inflection points where arc structures are connected. The handedness of the local optical activity was dependent on the handedness of the local chirality at the inflection point. Chiral chain structures have odd inflection points and the local optical activity distributed symmetrically with respect to structural centers. In contrast, achiral chain structures have even inflection points and showed antisymmetric distribution. In the near‐field CD images of fabricated chain nanostructures, the symmetric and antisymmetric distributions of local CD were observed for chiral and achiral chain structures, respectively, consistent with the simulated results. The handedness of the local optical activity was found to be determined by the handedness of the inflection point, for the fabricated chain structures having two or more inflection points. The local optical activity was thus governed primarily by the local chirality of the inflection points for the gold chain structures. The total effect of all the inflection points in the chain structure is considered to be a predominant factor that determines the macroscopic optical activity. Chirality 28:540–544, 2016. © 2016 Wiley Periodicals, Inc.     

The implementation of an environmental flow regime results in ecological recovery of regulated rivers

Environmental flows are the main restoration technique used to ameliorate the ecological effects of regulation in rivers. However, their effectiveness has yet to be unanimously accepted. This study assessed the potential ecological benefits of the application of an environmental flow regime downstream of four dams and two weirs in the Upper Nepean River system, Sydney, Australia. Aquatic macroinvertebrates in three habitat types were sampled at water‐supply and low‐flow sites and unregulated sites in 1995 and 1996, prior to the environmental flows and in 2013 and 2014, approximately 13 years following the environmental flows. The macroinvertebrate assemblage structure was significantly different between regulated and reference sites and the number of taxa lower at water‐supply sites prior to the implementation of the environmental flows. Following the environmental flows, the assemblage structure became more similar to, although still significantly different from, the unregulated sites and the number of taxa was not significantly different between regulated and unregulated sites. Thirteen or approximately 30% of taxa indicative of unregulated rivers increased in frequency at regulated sites following the environmental flows. Despite potentially similar dispersal capabilities the remainder of the taxa failed to respond the new flow regimes. The mechanisms resulting in recovery of some taxa but not others remain unclear and require further investigation as the basis of future research and monitoring. Such information and knowledge would support the application of future environmental flow regimes as the primary mechanism to ameliorate the ecological effects of river regulation.     

Autism‐related behaviors in the cyclooxygenase‐2‐deficient mouse model

Prostaglandin E2 (PGE2) is an endogenous lipid molecule involved in normal brain development. Cyclooxygenase‐2 (COX2) is the main regulator of PGE2 synthesis. Emerging clinical and molecular research provides compelling evidence that abnormal COX2/PGE2 signaling is associated with autism spectrum disorder (ASD). We previously found that COX2 knockout mice had dysregulated expression of many ASD genes belonging to important biological pathways for neurodevelopment. The present study is the first to show the connection between irregular COX2/PGE2 signaling and autism‐related behaviors in male and female COX2‐deficient knockin, (COX)‐2^?, mice at young (4‐6 weeks) or adult (8‐11 weeks) ages. Autism‐related behaviors were prominent in male (COX)‐2^? mice for most behavioral tests. In the open field test, (COX)‐2^? mice traveled more than controls and adult male (COX)‐2^? mice spent less time in the center indicating elevated hyperactive and anxiety‐linked behaviors. (COX)‐2^? mice also buried more marbles, with males burying more than females, suggesting increased anxiety and repetitive behaviors. Young male (COX)‐2^? mice fell more frequently in the inverted screen test revealing motor deficits. The three‐chamber sociability test found that adult female (COX)‐2^? mice spent less time in the novel mouse chamber indicative of social abnormalities. In addition, male (COX)‐2^? mice showed altered expression of several autism‐linked genes: Wnt2, Glo1, Grm5 and Mmp9. Overall, our findings offer new insight into the involvement of disrupted COX2/PGE2 signaling in ASD pathology with age‐related differences and greater impact on males. We propose that (COX)‐2^? mice might serve as a novel model system to study specific types of autism.     

Magnetic Field–Suppressed Lithium Dendrite Growth for Stable Lithium‐Metal Batteries

Lithium metal is the most attractive anode material due to its extremely high specific capacity, minimum potential, and low density. However, uncontrollable growth of lithium dendrite results in severe safety and cycling stability concerns, which hinders the application in next generation secondary batteries. In this paper, a new and facile method imposing a magnetic field to lithium metal anodes is proposed. That is, the lithium ions suffering Lorentz force due to the electromagnetic fields are put into spiral motion causing magnetohydrodynamics (MHD) effect. This MHD effect can effectively promote mass transfer and uniform distribution of lithium ions to suppress the dendrite growth as well as obtain uniform and compact lithium deposition. The results show that the lithium metal electrodes within the magnetic field exhibit excellent cycling and rate performance in a symmetrical battery. Additionally, full batteries using limited lithium metal as anodes and commercial LiFePO₄ as cathodes show improved performance within the magnetic field. In summary, a new and facile strategy of suppressing lithium dendrites using the MHD effect by imposing a magnetic field is proposed, which may be generalized to other advanced alkali metal batteries.     

Chelate-assisted phytoextraction of lead using Fagopyrum esculentum: laboratory vs. field experiments

Abstract

The development of more sustainable remediation techniques has been receiving greater attention, as an alternative to soil excavation plan in urban gardens. An in situ phytoextraction experiment with buckwheat (Fagopyrum esculentum) was performed with a 5?mmol kg^?1 citric acid (CA) application. Joint experiments under laboratory conditions were conducted using various cultivars of F. esculentum in two soils with a Pb contamination of either geogenic or anthropogenic origin and various chelate concentrations. Results show that a minimum dose of 50?mmol kg^?1 of CA is required to lower soil pH and raise the concentration of mobile Pb–CaCl₂ for both soils. Consequently, Pb shoot uptake is increased from 6.3 to 8.9 times depending on soil type. Phytoextraction efficiency is found to be 1.3 to 2.0 times higher in the anthropogenic contaminated soil than in the soil with geogenic Pb. A scale effect has also been identified since Pb root accumulation under laboratory conditions was 2.4 times higher than in the field experiment. Despite an increase in the Pb extraction rate with CA, buckwheat appears to lack the efficiency needed to remove Pb in moderately contaminated soils. The calculated remediation period would last 166?years to remove the mobile Pb fraction.     

Lithium Dendrites Inhibition via Diffusion Enhancement

The dendritic structure is a disastrous problem of lithium metal batteries as well as other metal rechargeable batteries. The dendritic structures are usually caused by diffusion limitation. Here, a novel strategy is reported to inhibit lithium dendrites based on the understanding of their formation mechanism. An alternating current field perpendicular to the anode is set up, which promotes Li⁺ movement along the anode surface and prevents ions' deposition on the tips from forming dendrites. Furthermore, an external direct current field parallel to the current is employed, which accelerates the transport of Li⁺ in electrolytes to mitigate the concentration gradient nearby the anode and thus inhibits the formation of dendritic structures. A simultaneous employment of these two fields gains five times increase of the lifespan of batteries at the high charging current density of 2 mA cm^?2, confirming the effectiveness of this strategy in protecting the metal anode and inhibiting lithium dendrites. This strategy may have a wide feasibility since it does not change the materials and structures of batteries.