Elucidation of transport mechanism and enhanced alkali ion transference numbers in mixed alkali metal-organic ionic molten salts

Mixed salts of Ionic Liquids (ILs) and alkali metal salts, developed as electrolytes for lithium and sodium batteries, have shown a remarkable ability to facilitate high rate capability for lithium and sodium electrochemical cycling. It has been suggested that this may be due to a high alkali metal ion transference number at concentrations approaching 50 mol% Li(+) or Na(+), relative to lower concentrations. Computational investigations for two IL systems illustrate the formation of extended alkali-anion aggregates as the alkali metal ion concentration increases. This tends to favor the diffusion of alkali metal ions compared with other ionic species in electrolyte solutions; behavior that has recently been reported for Li(+) in a phosphonium ionic liquid, thus an increasing alkali transference number. The mechanism of alkali metal ion diffusion via this extended coordination environment present at high concentrations is explained and compared to the dynamics at lower concentrations. Heterogeneous alkali metal ion dynamics are also evident and, somewhat counter-intuitively, it appears that the faster ions are those that are generally found clustered with the anions. Furthermore these fast alkali metal ions appear to correlate with fastest ionic liquid solvent ions.

One-way water-transport cotton fabrics with enhanced cooling effect

Two types of directional water transport fabrics are prepared by using cotton fabric as substrate and an electrospraying technique to apply a hydrophobic coating on one side of the fabric. The main difference between the two electrosprayed fabrics is that one of them was precoated with a hydrophilic thermoconductive resin over the fiber surface prior to electrospraying. As a result, the precoated fabric has a much higher thermoconductivity than the other, while they are similar in water transport and fibrous structure. In the wet state, the directional water-transport fabrics generate a temperature difference between the two fabric sides while drying naturally. The fabric with higher thermal conductivity shows smaller temperature difference, better thermal transfer within the fabric, stronger evaporation cooling effect, and accelerated moisture evaporation. Directional water transport fabrics with high thermal conductivity may be used to mitigate thermal burden in sportswear, summer clothing, medical fabrics, and workwear.

Directional fluid transport in thin porous materials and its functional applications

Directional fluid motion driven by the surface property of solid substrate is highly desirable for manipulating microfluidic liquid and collecting water from humid air. Studies on such liquid motion have been confined to dense material surfaces such as flat panels and single filaments. Recently, directional fluid transport through the thickness of thin porous materials has been reported by several research groups. Their studies not only attract fundamental, experimental and theoretical interest but also open novel application opportunities. This review article summarizes research progress in directional fluid transport across thin porous materials. It focuses on the materials preparation, basic properties associated with directional fluid transport in thin porous media, and their application development. The porous substrates, type of transporting fluids, structure-property attributes, and possible directional fluid transport mechanism are discussed. A perspective for future development in this field is proposed.

Perceived neighborhood environmental attributes sssociated with walking and cycling for transport among adult residents of 17 cities in 12 countries: the IPEN study

INTRODUCTION: Prevalence of walking and cycling for transport is low and varies greatly across countries. Few studies have examined neighborhood perceptions related to walking and cycling for transport in different countries. Therefore, it is challenging to prioritize appropriate built-environment interventions. OBJECTIVES: The aim of this study was to examine the strength and shape of the relationship between adults' neighborhood perceptions and walking and cycling for transport across diverse environments. METHODS: As part of the International Physical activity and Environment Network (IPEN) adult project, self-reported data were taken from 13,745 adults (18-65 years) living in physically and socially diverse neighborhoods in 17 cities across 12 countries. Neighborhood perceptions were measured using the Neighborhood Environment Walkability Scale, and walking and cycling for transport were measured using the International Physical Activity Questionnaire-Long Form. Generalized additive mixed models were used to model walking or cycling for transport during the last seven days with neighborhood perceptions. Interactions by city were explored. RESULTS: Walking-for-transport outcomes were significantly associated with perceived residential density, land use mix-access, street connectivity, aesthetics, and safety. Any cycling for transport was significantly related to perceived land use mix-access, street connectivity, infrastructure, aesthetics, safety, and perceived distance to destinations. Between-city differences existed for some attributes in relation to walking or cycling for transport. CONCLUSIONS: Many perceived environmental attributes supported both cycling and walking; however, highly walkable environments may not support cycling for transport. People appear to walk for transport despite safety concerns. These findings can guide the implementation of global health strategies.

Role of phosphate transport system component pstB1 in phosphate internalization by Nostoc punctiforme

In bacteria, limited phosphate availability promotes the synthesis of active uptake systems, such as the Pst phosphate transport system. To understand the mechanisms that facilitate phosphate accumulation in the cyanobacterium Nostoc punctiforme, phosphate transport systems were identified, revealing a redundancy of Pst phosphate uptake systems that exists across three distinct operons. Four separate PstB system components were identified. pstB1 was determined to be a suitable target for creating phenotypic mutations that could result in the accumulation of excessive levels of phosphate through its overexpression or in a reduction of the capacity to accumulate phosphate through its deletion. Using quantitative real-time PCR (qPCR), it was determined that pstB1 mRNA levels increased significantly over 64 h in cells cultured in 0 mM added phosphate and decreased significantly in cells exposed to high (12.8 mM) phosphate concentrations compared to the level in cells cultured under normal (0.8 mM) conditions. Possible compensation for the loss of PstB1 was observed when pstB2, pstB3, and pstB4 mRNA levels increased, particularly in cells starved of phosphate. The overexpression of pstB1 increased phosphate uptake by N. punctiforme and was shown to functionally complement the loss of PstB in E. coli PstB knockout (PstB(-)) mutants. The knockout of pstB1 in N. punctiforme did not have a significant effect on cellular phosphate accumulation or growth for the most part, which is attributed to the compensation for the loss of PstB1 by alterations in the pstB2, pstB3, and pstB4 mRNA levels. This study provides novel in vivo evidence that PstB1 plays a functional role in phosphate uptake in N. punctiforme IMPORTANCE: Cyanobacteria have been evolving over 3.5 billion years and have become highly adept at growing under limiting nutrient levels. Phosphate is crucial for the survival and prosperity of all organisms. In bacteria, limited phosphate availability promotes the synthesis of active uptake systems. The Pst phosphate transport system is one such system, responsible for the internalization of phosphate when cells are in phosphate-limited environments. Our investigations reveal the presence of multiple Pst phosphate uptake systems that exist across three distinct operons in Nostoc punctiforme and functionally characterize the role of the gene product PstB1 as being crucial for the maintenance of phosphate accumulation. We demonstrate that the genes pstB2, pstB3, and pstB4 show alterations in expression to compensate for the deletion of pstB1 The overall outcomes of this work provide insights as to the complex transport mechanisms that exist in cyanobacteria like N. punctiforme, allowing them to thrive in low-phosphate environments.