Uncovering the predictive pathways of lithium and sodium interchange in layered oxides.

Ion exchange is a powerful method to access metastable materials with advanced functionalities for energy storage applications. However, high concentrations and unfavourably large excesses of lithium are always used for synthesizing lithium cathodes from parent sodium material, and the reaction pathways remain elusive. Here, using layered oxides as model materials, we demonstrate that vacancy level and its corresponding lithium preference are critical in determining the accessible and inaccessible ion exchange pathways. Taking advantage of the strong lithium preference at the right vacancy level, we establish predictive compositional and structural evolution at extremely dilute and low excess lithium based on the phase equilibrium between Li0.94CoO2 and Na0.48CoO2. Such phase separation behaviour is general in both surface reaction-limited and diffusion-limited exchange conditions and is accomplished with the charge redistribution on transition metals. Guided by this understanding, we demonstrate the synthesis of NayCoO2 from the parent LixCoO2 and the synthesis of Li0.94CoO2 from NayCoO2 at 1-1,000 Li/Na (molar ratio) with an electrochemical assisted ion exchange method by mitigating the kinetic barriers. Our study opens new opportunities for ion exchange in predictive synthesis and separation applications.

Defining the challenges of Li extraction with olivine host: The roles of competitor and spectator ions.

The lithium supply issue mainly lies in the inability of current mining methods to access lithium sources of dilute concentrations and complex chemistry. Electrochemical intercalation has emerged as a highly selective method for lithium extraction; however, limited source compositions have been studied, which is insufficient to predict its applicability to the wide range of unconventional water sources (UWS). This work addresses the feasibility and identifies the challenges of Li extraction by electrochemical intercalation from UWS, by answering three questions: 1) Is there enough Li in UWS? 2) How would the solution compositions affect the competition of Li+ to major ions (Na+/Mg2+/K+/Ca2+)? 3) Does the complex solution composition affect the electrode stability? Using one-dimensional olivine FePO4 as the model electrode, we show the complicated roles of major ions. Na+ acts as the competitor ion for host storage sites. The competition from Na+ grants Mg2+ and Ca2+ being only the spectator ions. However, Mg2+ and Ca2+ can significantly affect the charge transfer of Li+ and Na+, therefore affecting the Li selectivity. We point to improving the selectivity of Li+ to Na+ as the key challenge for broadening the minable UWS using the olivine host.

A comparison of Hispanic middle school students' performance, and perceived and actual physical exertion, on the traditional and treadmill one-mile runs.

The purpose of this study was to assess whether a treadmill mile is an acceptable FitnessGram Test substitute for the traditional one-mile run for middle school boys and girls. Peak heart rate and perceived physical exertion of the participants were also measured to assess students' effort. 48 boys and 40 girls participated, with approximately 85% classified as Hispanic. Boys' mean time for the traditional one-mile run, as well as peak heart rate and perceived exertion, were statistically significantly faster and higher, respectively, than for the treadmill mile. Girls' treadmill mile times were not statistically significantly different from the traditional one-mile run. There were no statistically significant differences for girl's peak heart rate or perceived exertion. The results suggest that providing middle school students a choice of completing the FitnessGram mile run in either traditional one-mile run or treadmill one-mile format may positively affect performance.

Tuning transport in graphene oxide membrane with single-site copper (II) cations.

Controlling the ion transport through graphene oxide (GO) membrane is challenging, particularly in the aqueous environment due to its strong swelling tendency. Fine-tuning the interlayer spacing and chemistry is critical to create highly selective membranes. We investigate the effect of single-site divalent cations in tuning GO membrane properties. Competitive ionic permeation test indicates that Cu2+ cations dominate the transport through the 2D channels of GO membrane over other cations (Mg2+/Ca2+/Co2+). Without/With the single-site M2+ modifications, pristine GO, Mg-GO, Ca-GO, and Cu-GO membranes show interlayer spacings of ∼13.6, 15.6, 14.5, and 12.3 Å in wet state, respectively. The Cu-GO membrane shows a two-fold decrease of NaCl (1 M) permeation rate comparing to pristine GO, Mg-GO, and Ca-GO membranes. In reverse osmosis tests using 1000 ppm NaCl and Na2SO4 as feeds, Cu-GO membrane shows rejection of ∼78% and ∼94%, respectively, which are 5%-10% higher than its counterpart membranes.

Be well, sleep well: An examination of directionality between basic psychological needs and subjective sleep among emerging adults at university.

OBJECTIVES: The present study assessed bidirectional associations between basic psychological needs and several subjective sleep variables across 2 semesters. DESIGN: Participants completed an online survey twice (7 months apart) as part of a short-term longitudinal, correlational study. PARTICIPANTS: Participants were 154 (67.8% female) emerging adults (mean age = 20.02 years, SD = 1.71) from a liberal arts university on the east coast. MEASUREMENTS: Survey assessed demographics, perceived fulfillment of basic psychological needs (autonomy, competence, and relatedness), and several sleep variables (week and weekend sleep duration, sleep disturbances, daytime dysfunction, and sleep quality; Pittsburgh Sleep Quality Index). RESULTS: Data were analyzed using an autoregressive cross-lagged model, which controlled for level of study, diagnosis of mental illness, self-esteem, social desirability, sleeping medication, chronotype, conscientiousness, and extraversion. Results indicated significant unidirectional associations: perceived fulfillment of basic psychological needs predicted longer week sleep duration (ß = .243, P = .008) and better perceived sleep quality (ß = -.223, P = .008) 1 semester later, and 1 significant bidirectional association, perceived fulfillment of basic psychological needs, predicted lower daytime dysfunction, and in turn, lower daytime dysfunction predicted higher perceived fulfillment of basic psychological needs 1 semester later. CONCLUSIONS: Although many sleep interventions focus on environmental aspects of sleep, our findings highlight the importance of nurturing university students' psychological needs as a potential point of intervention for improving some sleep characteristics among emerging adults at university.

Effects of Instructional Physical Activity Courses on Overall Physical Activity and Mood in University Students.

PURPOSE: The aim of this research was to assess the association between university-based instructional physical activity (PA) courses and changes in overall PA levels and negative mood and their interrelations. The study also sought to determine the amount of change in PA required to significantly improve mood in course enrollees. METHOD: Participants were university students initially completing PA below the level recommended for health who were either presently enrolled in an elective instructional PA course (treatment group, n = 52, 69% female) or not presently enrolled in such a course (comparison group, n = 32, 69% female). Validated surveys assessed volumes of PA completed per week and overall negative mood from baseline to course end. Mediation analyses assessed group effects on mood through PA changes and reciprocal relations between PA and mood changes. RESULTS: There was a significantly greater increase in PA and significantly more reduction in negative mood in the treatment group. Change in PA completely mediated the relationship between group and change in negative mood, and change in mood completely mediated the relationship between group and PA. These findings indicated a reciprocal, mutually reinforcing relationship between changes in PA and mood. An increase in PA of at least 2 days/week was associated with a significant reduction in negative mood, with no greater effect for more increase. CONCLUSIONS: Results provided an improved understanding of the effects of university-based instructional PA courses and how they might be leveraged to improve students' mental health and possibly contribute to their academic success.

Corrosion Protection of Copper Using Al2O3, TiO2, ZnO, HfO2, and ZrO2 Atomic Layer Deposition.

Atomic layer deposition (ALD) is a viable means to add corrosion protection to copper metal. Ultrathin films of Al2O3, TiO2, ZnO, HfO2, and ZrO2 were deposited on copper metal using ALD, and their corrosion protection properties were measured using electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV). Analysis of ∼50 nm thick films of each metal oxide demonstrated low electrochemical porosity and provided enhanced corrosion protection from aqueous NaCl solution. The surface pretreatment and roughness was found to affect the extent of the corrosion protection. Films of Al2O3 or HfO2 provided the highest level of initial corrosion protection, but films of HfO2 exhibited the best coating quality after extended exposure. This is the first reported instance of using ultrathin films of HfO2 or ZrO2 produced with ALD for corrosion protection, and both are promising materials for corrosion protection.

Guidelines for the uniform reporting of data for Medical Emergency Teams.

It is more than 15 years since the first Medical Emergency Team (MET) system was introduced to identify patients at risk and prevent serious adverse events in Liverpool Hospital, Sydney, Australia. Since then the MET system has been introduced to many other hospitals in Australia and around the world. Standardised and complete reporting of data related to MET activity is increasingly important to identify the role and benefits of the system and to facilitate quality improvement in health care in general. A uniform method for reporting data related to MET activity will aid interpretation of results, comparisons, review and changes to the MET system. The guidelines for uniform reporting of data in relation to MET activities used in our group of hospitals are presented. Future refinement and consensus agreement on the reporting of MET data internationally should enable comparisons between MET systems in several countries.

Parent volatiles in comet 9P/Tempel 1: before and after impact.

We quantified eight parent volatiles (H2O, C2H6, HCN, CO, CH3OH, H2CO, C2H2, and CH4) in the Jupiter-family comet Tempel 1 using high-dispersion infrared spectroscopy in the wavelength range 2.8 to 5.0 micrometers. The abundance ratio for ethane was significantly higher after impact, whereas those for methanol and hydrogen cyanide were unchanged. The abundance ratios in the ejecta are similar to those for most Oort cloud comets, but methanol and acetylene are lower in Tempel 1 by a factor of about 2. These results suggest that the volatile ices in Tempel 1 and in most Oort cloud comets originated in a common region of the protoplanetary disk.