A latent growth curve model to estimate electronic screen use patterns amongst adolescents aged 10 to 17 years

Background: High quality, longitudinal data describing young people's screen use across a number of distinct forms of screen activity is missing from the literature. This study tracked multiple screen use activities (passive screen use, gaming, social networking, web searching) amongst 10- to 17-year-old adolescents across 24 months. Methods: This study tracked the screen use of 1948 Australian students in Grade 5 (n = 636), Grade 7 (n = 672), and Grade 9 (n = 640) for 24 months. At approximately six-month intervals, students reported their total screen time as well as time spent on social networking, passive screen use, gaming, and web use. Patterns of screen use were determined using latent growth curve modelling. Results: In the Grades 7 and 9 cohorts, girls generally reported more screen use than boys (by approximately one hour a day), though all cohorts of boys reported more gaming. The different forms of screen use were remarkably stable, though specific cohorts showed change for certain forms of screen activity. Conclusion: These results highlight the diverse nature of adolescent screen use and emphasise the need to consider both grade and sex in future research and policy

A flexible back-contact perovskite solar micro-module

Back-contact perovskite solar cells are fabricated by depositing methylammonium lead iodide perovskite into micron-sized grooves, with opposite walls of each groove being coated with either n- or p-type selective contacts. V-Shaped grooves are created by embossing a polymeric substrate, with the different charge-selective electrodes deposited onto the walls of the groove using a directional evaporation technique. We show that individual grooves act as photovoltaic devices, having a power conversion efficiency of up to 7.3%. By series-connecting multiple grooves, we create integrated micro-modules that build open circuit voltages up to nearly 15 V and power conversion efficiencies over 4%. The devices created are fully flexible, do not include rare metals, and are processed using techniques applicable to roll-to-roll processing

Optimizing the mass-specific activity of bilirubin oxidase adlayers through combined electrochemical quartz crystal microbalance and dual polarization interferometry analyses

Two surface analysis techniques, dual polarization interferometry (DPI) and analysis by an electrochemical quartz crystal microbalance with dissipation capability (E-QCM-D), were paired to find the deposition conditions that give the highest and most stable electrocatalytic activity per adsorbed mass of enzyme. Layers were formed by adsorption from buffered solutions of bilirubin oxidase from Myrothecium verrucaria at pH 6.0 to planar surfaces, under high enzyme loading (≥1 mg mL^–1) for contact periods of up to 2 min. Both unmodified and carboxylate-functionalized gold-coated sensors showed that a deposition solution concentration of 10–25 mg mL^–1 gave the highest activity per mass of adsorbed enzyme with an effective catalytic rate constant (<i>k</i>_cat) of about 60 s^–1. The densification of adsorbed layers observed by DPI correlated with reduced bioactivity observed by parallel E-QCM-D measurements. Postadsorption changes in thickness and density observed by DPI were incorporated into Kelvin–Voigt models of the QCM-D response. The modeled response matched experimental observations when the adlayer viscosity tripled after adsorption

Surface analysis measurements of the adsorption of bilirubin oxidase from Myrothecium verrucaria

Content type: Research data Research data type: Experimental data Created date: 2015-8-05 Last modified date: 2015-11-07 Abstract: Data recorded from: - an electrochemical quartz crystal microbalance (EQCMD, files ending in .qsd) using a Q-Sense E1 QCMD with a modified QEM401 flow cell (files readable in QTools) - a potentiostat (files ending in .ids) using an Ivium CompactStat (files readable in IviumSoft) - a Farfield dual polarization interferometer (DPI, files ending in .xpt) Processed data in Excel spreadsheets (.xlsx) and Origin Project Files (.opj). Data relate to the concentration-dependent adsorption of the enzyme bilirubin oxidase from Myrothecium verrucaria (MvBOx) on bare gold and silica surfaces, and those modified to provide a surface with a uniform charge or polarity. Table of contents: Surface modifications EQCMD DPI.zip - EQCMD: frequency, dissipation and current responses to the adsorption of MvBOx on gold sensor surfaces modified with short- and long-chain modifiers terminated with positive, negative or apolar groups. - DPI: phase and refractive index data for the same, but with silane-modified silicon oxynitride sensor surfaces increasing concentration 3MPA EQCMD DPI.zip - EQCMD - Concentration increase on 3MPA: raw and processed QCMD and electrochemical data for MvBOx adsorption on gold sensors modified with 3-mercaptopropionic acid (3MPA) for concentrations from 1 to 50 mg/ml - Concentration increase on gold: data as for previous but taken from unmodified (bare gold) QCM sensors - Concentartion increase BSA on SiOx: data as for previous but taken from bare silicon oxide coated QCM sensors - DPI: Excel file with combined processed data for MvBOx adsorption on bare DPI sensors from solutions from 0.1 to 15 mg/ml Viscosity measurements.xlsx: Falling ball viscometer measurements for MvBOx solutions and fits using Solver to Huggins and Kraemer models

A versatile route to edge-specific modifications to pristine graphene by electrophilic aromatic substitution

This work presents a general method for producing edge-modified graphene using electrophilic aromatic substitution. Five types of edge-modified graphene were created from graphene/graphite nanoplatelets sourced commercially and produced by ultrasonic exfoliation of graphite in N-methyl-2-pyrrolidone. In contrast to published methods based on Friedel–Crafts acylation, this method does not introduce a carbonyl group that may retard electron transfer between the graphene sheet and its pendant groups. Graphene sulphonate (G–SO3−) was prepared by chlorosulphonation and then reduced to form graphene thiol (G–SH). The modifications tuned the graphene nanoparticles’ solubility: G–SO3− was readily dispersible in water, and G–SH was dispersible in toluene. The synthetic utility of the directly attached reactive moieties was demonstrated by creating a “glycographene” through radical addition of allyl mannoside to G–SH. Chemical modifications were confirmed by FT-IR and XPS. Based on XPS analysis of edge-modified GNPs, G–SO3− and G–SH had a S:C atomic ratio of 0.3:100. XPS showed that a significant amount of carbon sp2 character remained after functionalisation, indicating little modification to the conductive basal plane. The edge specificity of the modifications was visualised on edge-modified samples of graphene produced by chemical vapour deposition (CVD): scanning electron microscopy of gold nanoparticles attached to G–SH samples, epifluorescence microscopy of a glycographene bioconjugate with a fluorescently tagged lectin, and quenched stochastic optical reconstruction microscopy (qSTORM) of thiol-reactive fluorophores on CVD G–SH samples. Microelectrochemistry of unmodified CVD graphene and dye-modified CVD G–SH showed no statistically significant difference in interfacial electron transfer rate (k0). This platform synthesis technology can allow pristine graphene, rather than graphene oxide or its derivatives, to be used in applications that require the superior mechanical or electronic properties of pristine graphene, including theranostics and tissue engineering

A versatile route to edge-specific modification of graphene nanoplatelets by electrophilic aromatic substitution

Raw data files, figure components and Origin file containing data and figure