Use Of Portable Electronic Devices Research Articles

Nanomechanical measurements shed light on solid-state battery degradation

Abstract

High performance hybrid-capacitor based on MoTe2/graphene through ultra-fast, facile microwave-initiated synthesis

With the rapid development of world economy and an increasing use of portable electronic devices, energy storage systems are becoming more reliable on nano/micro supercapacitors. This work reports a fast and facile microwave-initiated synthesis approach of 2D-molybdenum ditelluride nanosheets supported on graphene substrate (MoTe2/graphene), which can be used as an efficient energy storage material. The physical characterizations, such as scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses substantiate the successful synthesis of MoTe2/graphene nanocomposite. The electrochemical characterizations reveal their excellent supercapacitive behavior with specific capacitance of 434 ± 37.5 F g−1 at a current density of 1 A g−1 and a good cycling stability of 125% retention after 5000 cycles at 10 A g−1 in 1 M Na2SO4 aqueous solution. In addition, the symmetric MoTe2/graphene//MoTe2/graphene configuration displays excellent cyclic stability up to 10,000 cycles with a maximum energy density of 43.2 Wh kg−1 at high power density of 3000 W kg−1 in 1 M Na2SO4 electrolyte, which demonstrates the hybrid-capacitor behavior. Therefore, the microwave synthesized MoTe2/graphene reveals a great potential as advanced electrode materials for energy storage devices with high electrochemical performance through one-step facile synthesis approach.

Porous Silicon-Cobalt Silicide-Carbon Composites for Reversible Lithium Storage

With increasing use of portable electronic devices and electric vehicles, demand for development of high-energy density rechargeable batteries is rising. To meet the market demand for long-lasting rechargeable batteries, energy density of Li-ion batteries (LIBs) should be increased. The energy density of batteries is determined by the capacities of electrodes. Carbonaceous materials have been used as negative electrodes (anodes) in commercial LIBs because of their low operating potential and reasonable cycle life. However, the theoretical capacity of graphite anodes is relatively low, which is 372 mAh g-1 for the fully intercalated LiC6 phase. To increase the capacity, different types of materials using alloying or conversion reaction should be developed. Li-alloy-based materials can store several Li ions with an atom by electrochemical alloying reactions and therefore, high capacity can be obtained. In particular, Si has a high theoretical capacity of 3580 mAh g-1 for Li15Si4 and low operating potential. However, serious capacity fading usually occurs because of huge volume changes during cycling and their low electric conductivity. To address this problem, many strategies have been developed through changes in materials design. For example, incorporation of carbon is the most famous method to solve the capacity fading of Li-alloy-based materials upon cycling. The existence of carbon in Si matrix can buffer the volume expansion of Si materials with increased electric conductivity, thus simultaneously improving both cycling and rate performance. Porous structure can be another strategy to relieve the volume expansion by using the internal pores. However, the process is generally time and energy consuming. In this study, we report a simple preparation process of porous Si-CoSi2-C composites as anode materials for LIBs. The porous composite was synthesized through cheap starting materials and cost-effective methods. Si, magnesium silicide, and cobalt oxide were mixed using high energy mechanical milling (HEMM). Then, a carbon material was incorporated by HEMM. To produce porous structure, MgO formed by HEMM was removed by a wet etching process. As a result, porous Si-CoSi2-C composites were prepared. These composites exhibited a reversible capacity of 1100 mAh g-1 and good capacity retention after 100 cycles. The porous structure and the amorphous carbon matrix alleviated the volume change to allow the enhanced electrochemical performance.

The effectiveness of mHealth interventions on postpartum depression: A systematic review and meta-analysis

Introduction Postpartum depression (PPD) is a common psychiatric condition during the postnatal period that negatively impacts the well-being of both the mother and her infant. This study describes a systematic review and preliminary meta-analysis to assess the efficacy of mobile health (mHealth) interventions, which is defined as the use of portable electronic devices to support public health and medical practice, in addressing depressive symptoms among postpartum women. Methods Databases including PubMed, PsycINFO, the Cochrane Library, Embase and ClinicalTrials.gov were searched for randomized controlled trials (RCTs) assessing the effectiveness of mHealth interventions on PPD from database inception to December 2019. Results The initial search identified 754 studies, of which, 11 studies fulfilled the inclusion criteria. These studies evaluated four types of distinct mHealth interventions and involved 2424 participants across six countries. Pooled results demonstrated that compared to the controls, the Edinburgh Postnatal Depression Scale score decreased in the mHealth intervention group (mean difference: –1.09, 95% confidence interval: –1.39 to –0.79). Discussion Our study suggested that mHealth interventions may be a promising tool to complement routine clinical care in the prevention and treatment of PPD, but the clinical effectiveness of mHealth interventions needs to be better established. While most studies focused on telephone-based interventions, recent researches have also suggested the superiority and effectiveness of short messaging service (SMS) and smartphone applications, but the exact efficacy needs further evaluation. Therefore, more high-quality RCTs on app-based and SMS-based interventions are needed before the large-scale roll-out of these interventions in clinical practice.

Electronic device use in bed reduces sleep duration and quality in adults

The purpose of this study was to explore the impact that portable electronic device use in bed after lights out has on sleep/wake behaviour within an adult population. Specifically, this study aimed to (1) identify patterns of use of electronic devices in bed; (2) examine the relationship between electronic device use in bed and sleep/wake behaviour; and (3) examine the impact of demographic variables on electronic device use in bed. Using a cross-sectional design, telephone interviews were conducted with 1,225 participants (52% female). Survey questions asked about participant demographic variables, their sleep/wake history, and their pre-sleep behaviours, which included electronic device usage. Forty-two percent of participants reported using electronic devices in bed after lights out, and 27% of adults who reported ‘always’ using electronic devices in bed were spending over an hour per night using them. Sleep characteristics were significantly different in device users compared to non-device users (p < 0.001). Frequency of device use was associated with later sleep times, and duration of device use was associated with shorter sleep duration and decreased sleep quality. Older adults were less likely to use devices in bed after lights out, and had less duration of usage. Electronic device use in bed was found to reduce sleep duration and sleep quality in adults. To further our understanding of the impact device use in bed has on adult sleep behaviour, future studies should consider employing objective measurements of both sleep behaviour and device usage.

Key Aspects of Lithium Metal Anodes for Lithium Metal Batteries.

Rechargeable batteries are considered promising replacements for environmentally hazardous fossil fuel-based energy technologies. High-energy lithium-metal batteries have received tremendous attention for use in portable electronic devices and electric vehicles. However, the low Coulombic efficiency, short life cycle, huge volume expansion, uncontrolled dendrite growth, and endless interfacial reactions of the metallic lithium anode are major obstacles in their commercialization. Extensive research efforts have been devoted to address these issues and significant progress has been made by tuning electrolyte chemistry, designing electrode frameworks, discovering nanotechnology-based solutions, etc. This Review aims to provide a conceptual understanding of the current issues involved in using a lithium metal anode and to unveil its electrochemistry. The most recent advancements in lithium metal battery technology are outlined and suggestions for future research to develop a safe and stable lithium anode are presented.

Modeling and Simulation of Frequency Response Masking FIR Filter Bank using Approximate Multiplier for Hearing Aid Application

The tremendous increase in the use of portable electronic devices is due to the development in the fields of signal processing and electronic technology. These battery operated devices needs reduction in power consumption with increased performance and long battery life. Since CMOS technology scaling fast approaches its physical limit of minimum supply voltage and smaller feature size, the hardware designer has to opt for new multiplier architectures for achieving low power and high speed performance. This paper proposes an area and power efficient approximate multiplier architecture. The error metrics are estimated to verify its performance advantage over other approximate multipliers. Using Frequency Response masking approach, a 6-band non-uniform digital FIR filter bank is developed using approximate multiplier for hearing aid application. Audiogram matching is done with audiograms of two different types of hearing losses and the matching error is computed. Simulation results show that the audiogram matching error falls within +/- 4 dB range.

Youth Screen Media Habits and Sleep: Sleep-Friendly Screen Behavior Recommendations for Clinicians, Educators, and Parents.

With the widespread use of portable electronic devices and the normalization of screen media devices in the bedroom, insufficient sleep has become commonplace. In a recent literature review, 90% of included studies found an association between screen media use and delayed bedtime and/or decreased total sleep time. This pervasive phenomenon of pediatric sleep loss has widespread implications. There is a need for basic, translational, and clinical research examining the effects of screen media on sleep loss and health consequences in children and adolescents to educate and motivate clinicians, teachers, parents and youth themselves to foster healthy sleep habits.

Batteries in Portable Electronic Devices: A User's Perspective

Batteries have enabled the use of portable electronic devices, including smartphones, laptops, tablets, e-book readers, and global positioning system (GPS) devices. This article documents the results from two surveys of 1,200 respondents from the United States intended to understand users' satisfaction, concerns, charging habits, and expectations with respect to the batteries in their portable electronic devices. The results are useful for requirements planning and comparing different portable electronic devices using the metrics of usage habits and batteryrelated expectations.

Factors Affecting the Electrochemical Performance of Graphene like Graphite

Lithium-ion batteries with high energy density, compact size and good cycling performance are attracting much attention for the use of portable electronic devices, electric vehicles and energy storage devices. Graphite is mainly used for the anode materials of them, however, further improvements are needed in terms of both power and energy densities. It has been reported that graphene-based anode materials show high power density and capacity exceeding 1000 mAh/g. However, graphene is known to suffer from a large irreversible capacity due to its intrinsically large surface area. Recently, we have introduced a novel graphene like graphite (GLG) with low surface area and similar interlayer spacing to that of graphite, which was prepared from the thermal reduction of graphite oxide (GO). It showed the capacity of 600 mAh/g, high rate capability and higher coulombic efficiency. In this study, we have prepared GLG samples with various structural parameters and investigated their electrochemical performance in detail.GO was prepared from natural graphite using modified Brodie’s method. The as-prepared GO was dispersed in 0.1M NH3 aq at various concentrations (0.2-3.0 mg/ml), then the dispersions were spray-dried at 100 or 150℃. The resulting GO samples were heated at 700 – 1000°C under vacuum and GLG with different structural parameters were obtained. The constant current charge-discharge measurement was performed using a two-electrode cell with lithium metal and 1M LiClO4-EC+DMC (1:1) as counter electrode and electrolyte, respectively.The interlayer spacing, Lc, La and oxygen contents of the resulting GLG samples were 0.336 –0.353 nm, 7.1 – 57 nm, 7.8 -23 nm and 1.0 – 5.1 %, respectively. Based on these parameters and the shape of discharge curves of them, we have concluded that the oxygen content in them is more directly related to their capacity.

Electrochemical Properties of Porous V2O5/Sulfur/Carbon Composite Electrode Prepared Using a Combination of Aerosol and Powder Technologies

The increase in the demand for clean and sustainable energy has prompted intense effort towards the realization of high-performance energy storage technologies. Among the many available energy storage technologies, lithium(Li)-ion batteries with Li-intercalation compounds as positive electrodes have achieved great success for use in portable electronic devices [1, 2]. A typical rechargeable Li-ion battery requires heavy host compounds (e.g., CoO2) to accommodate guest atoms (e.g., Li), which greatly limits its energy density to less than 210 Wh kg-1. On the other hand, a Li-sulfur (S) battery as a typical integration reaction battery system [4] may open a new horizon for electric vehicles. As the sulfur cathode has a theoretical specific capacity of 1672 mAh g-1, a Li-S battery can achieve an energy density of 2654 Wh kg-1when combined with a lithium metal anode, which is 3-5-fold higher than those of current Li-ion batteries [5]. In addition, sulfur is a highly abundant element source on earth and is not geographically isolated [6], which may reduce the cost of cathode materials. However, Li-S batteries have serious problems [7-9], including low utilization of the active material and a poor cycle life because of the insulating property of sulfur and the high solubility of lithium polysulfides in organic electrolytes. To overcome the above-mentioned problems, much effort has been devoted to designing S-based cathodes, thus far. Various elegantly designed carbons have been studied for use as sulfur hosts to enhance the electronic conductivity of sulfur and trap polysulfides within a carbon framework simultaneously. However, carbon is an electrochemically inactive material in the integration reaction of Li-S batteries, and therefore its quantity in the electrode should be reduced as much as possible. Vanadium pentoxide (V2O5) is one of the most common cathode materials in the field of Li batteries and has a few advantages when used as an additive in sulfur cathodes. It is an electrochemically active material in the cut-off voltage range from 1.5 to 4 V, which closely matches that for sulfur cathodes (from 1.5 to 3 V), and it also positively contributes to the capacity of sulfur cathodes. In this study, S/Carbon/porousV2O5nanocomposites were prepared by a novel synthesis route and their physical and electrochemical properties were further investigated.Porous V2O5 particles were firstly prepared by spray pyrolysis (SP) with NH4NO3 additive. The pore structure of obtained samples were analyzed by N2 adsorption-desorption isotherm measurements. The V2O5 particles with pore size less than 100 nm could be prepared at 500 ºC by SP with a 0.272 mol L-1 NH4NO3 additive, and the porous V2O5 electrode exhibited a first discharge capacity of 400 mAh g-1 at 20 mA g-1.The as-prepared porous V2O5 were packed with acetylene black and S at a targeted ration in a closed reactor. The reactor was heated at different temperatures ranging from 120 to 200 ºC. The effect of S content, heating temperature and heating time were investigated systematically. Figure 1 shows the cycle performance of the S/C/porous V2O5 composite electrode at a charge-discharge rate of 100 mA g-1. The cycle performance of the S/C composite electrode is also shown in the figure as a comparison. The S/C/porous V2O5 composite electrode exhibits a discharge capacity of 666 mAh g-1 at 50th cycles, while the S/C composite electrode shows a discharge capacity of 379 mAh g-1 at 50th cycles . As seen from this fact, the S/C/porous V2O5 composite electrode shows larger discharge capacities and better cycle performance than the S/C composite electrode. This fact indicate that the V2O5additive to the S/C composite electrode leads to enhance its electrochemical performance.

In-Operando X-Ray Diffraction of Na-Ion Batteries

Future demand for lithium-ion batteries is predicted to increase continuously due to their use in portable electronic devices and larger-scale energy storage, such as hybrid electric vehicles and static energy storage systems. Sodium is ubiquitous and significantly cheaper than lithium. Recent advances in sodium-ion battery technology has achieved promising results, with energy, power and cycle life comparable to Li-ion technology.1 Among cathode candidates, layered oxides offer many advantages due to their simple structures, high capacities, and ease of synthesis. However, there are major challenges to overcome, such as: low operating voltage, long term stability of host structure, high polarisation and the stability of the sodium in the P2-phase.2 In general, ternary and quaternary transitional metal (TM­) systems offer the most advantages, due to the ability to tune the material with different TM at different percentages. SHARP Corp. have been developing a variety of layered oxides for sodium-ion battery applications. One of the most promising candidates to date is the quaternary TM system, NaNixSnyMnzTiyO2 giving an experimental capacity of 175 mAh/g and an average voltage of 3.2 V. However, the cycle stability of this material requires improvement. In order to understand this loss in capacity over cycle life, in-operando x-ray diffraction was carried out in coin cell configuration vs hard carbon, containing either one or two beryllium windows depending on the x-ray source used. Initially, this project looked at the material in-situusing low energy laboratory x-ray diffraction, but the energy of the x-ray source is not sufficient to identify the different phase transitions throughout sodiation/desodiation. By means of using a synchrotron x-ray source and following real-time electrochemical performance, this experiment has allowed the identification of key phase transitions throughout initial sodiation at a rate of C/20 then continued cycling at a rate of C/10. What is particularly interesting is the corresponding phase transition that occurs at high voltage, with a defined plateau from 3.9 to 4.3 V. The corresponding redox reaction is unstable thus small loses of capacity is observed through cycling. By identifying this phase, and understanding what the structural changes to the cathode material are, there is the possibility to tune this material and therefore stabilising this high voltage phase-transition.

Investigating New Electrode Materials for Better Sodium-Ion Batteries

Currently the extensive use of portable electronic devices have given rise to the high demand for reliable high energy density storage in the form of batteries. Today, lithium-ion batteries (LIBs) are the leading technology as they offer high energy density and relatively long lifetimes.[1] However, safety issues and the rarity of lithium brings about the relatively high cost of these batteries.[2] To address this issue, sodium-ion batteries (SIBs) have been developed as a low cost alternative for LIBs.[2, 3] Sodium’s similar chemistry to lithium enables accessible parallel implementation of LIB technology into SIB and its natural abundance ensures that sodium can be acquired at a much cheaper price compared to lithium.[4, 5] Recent development of sustainable and clean energy sources such as solar and wind has also escalated the need for SIBs.[4, 6] The unstable supply of energy generated from these renewable energy sources makes an efficient and reliable energy storage system crucial to ensure a continuous flow of energy during times where the energy production is poor.[3, 6] Such large scale stationary energy storage systems will be unsuitable for LIBs due to its relatively high cost, however with SIBs this could be realized.[3] Nonetheless, challenges still remain for the development of SIBs. Optimization of electrode materials capable of reversible insertion/extraction of sodium-ions in a safe and economic way under high current density are required in order to produce commercially viable SIBs.[2, 7] Present materials commonly investigated for SIB positive electrodes are metal oxides, phosphates, sulfates and metal-organic frameworks (MOF), while carbon based materials are still a favorable choice as negative electrodes due to its low potential against Na, natural abundance, renewability, and low cost.[3, 4] Despite the fact that the reversible intercalation of sodium-ion into/from graphite is not significant, research has shown that other carbon based materials can be used.[8-10]. Although these electrode materials in SIBs have been studied from an electrochemical perspective, further work is still needed to understand the insertion/extraction mechanism of sodium ions into these materials and more importantly how sodium moves inside these materials. As the structure and chemical environment of materials are closely related to their properties, it is very important to understand the mechanism to be able to design new materials with desired properties. In this study, we use a combination of in-situ X-ray diffraction (XRD), solid state nuclear magnetic resonance (SS-NMR) and quasi-elastic neutron scattering (QENS) to study the mechanism of sodium-ion insertion/extraction in some selected electrode materials. XRD will provide long range ordering of the structure of the material. SS-NMR will provide the local environment of the sodium, and QENS enables insight on the diffusion mechanism of the sodium ions inside the selected materials. The combination of these three techniques will provide a more complete picture of the mechanism of sodium-ion insertion/extraction and movement inside the electrode materials. If these mechanisms can be properly understood, it will be possible to design a safe and reliable SIB which could be an alternative to LIB realizing a cheaper energy storage system for the world. This talk will focus on our first results based on carbon based materials such as carbon nanotubes and graphene. With characterization using XRD and SS-NMR we were able to compare the structure and the chemical environment of the sodium within these carbons after charge and discharge, giving interesting insight on how these materials will behave in a battery.

Cobalt Phthalocyanine Analogues As Soluble Catalysts That Improve the Charging Performance of Li-O2 Batteries

There is growing demand for the rechargeable aprotic Li-air (or Li-O2) batteries with high energy density for use in portable electronic devices and electric vehicles, as the performance of Li-ion batteries approaches the theoretical limit of energy density. For an aprotic Li- O2 battery, an insoluble film of lithium peroxide (Li2O2) is formed at the positive electrode during the discharge process, which is electrochemically decomposed with the evolution of O2 gas during the charge process. As the overpotentials for the positive electrode reactions are high, various electrocatalysts, including noble metals, metal oxides, metal nitrides, and heat-treated metal complexes, have been developed. Although such electrocatalysts deposited on electrode substrates have improved the battery performance during the initial stage of reaction, the catalytic activity gradually declines as the electrocatalysts become buried in the Li2O2formed over time during the discharge process. One approach to overcome this inherent problem with electrocatalysts is to use a soluble catalyst that can repeatedly adsorb on the growing or dissolving Li2O2 front. However, the solubility of the catalyst used so far was less than several millimoles per liter, which would prevent further improvement of the charging performance. We have recently reported in a three-electrode system that metal complexes with nitrogen-containing macrocyclic ligands, such as metal porphyrin and metal phthalocyanine, can generally catalyze the aprotic OER. Although cobalt phthalocyanine adsorbed on carbon substrate was known to serve as an adsorbed electrocatalyst, our previous study revealed that such metal complexes could function also as soluble catalysts. In addition, we also revealed that the onset potential of the OER was determined by the redox potential of the metal complexes. These results suggest that a metal complex with both a more negative redox potential and with high solubility would function as a good catalyst for Li-O2 batteries. Herein, we demonstrate that tb-CoPc could serve as an OER catalyst that exhibits superior charging performance for Li-O2batteries. The effect of tb-CoPc addition on the discharge/charge characteristics was investigated using a coin type cell. Although both cells showed a stable discharge potential at around 2.7 V, there is a clear difference between the charging profiles. For the cell without tb-CoPc, the charging potential was around 4.0 V and then finally reached ca. 4.3 V (black line in Figure). In contrast, the cell with 10 mM tb-CoPc exhibited better charging performance (red line in Figure). To confirm the effect of the high solubility of tb-CoPc, the effect of CoPc addition, which has lower solubility than tb-CoPc due to the lack of tert-butyl-groups, was investigated. The solubility of CoPc in the representative Li-ion electrolyte that was used (i.e., 1 M Li trifluoromethanesulfonate dissolved in triethylene glycol dimethyl ether (TEGDME)) was not more than 1 mM. Notably, the redox potential of tb-CoPc is more negative than that of CoPc, which is also advantageous for the charging process. However, the charging performance was not so improved when the concentration of tb-CoPc is 1 mM, indicating that the improved charging performance in the presence of 10 mM tb-CoPc is mainly due to the higher solubility of tb-CoPc compared with CoPc. Next, the formation and decomposition of Li2O2 in the presence of tb-CoPc was investigated. X-ray diffraction (XRD) analyses revealed that the dominant product at the positive electrode surface from the discharge process was crystallized Li2O2. After the charge process, the XRD peaks attributed to Li2O2 disappeared, which indicated that Li2O2was decomposed during the charging process. In conclusions, we have demonstrated that tb-CoPc functions as a soluble catalyst on the positive electrode for rechargeable Li-O2 batteries. The superior discharge/charge processes accompanied with the reversible formation and decomposition of Li2O2 indicates that tb-CoPc functions as an OER catalyst without changing the reaction scheme. We speculate that the soluble tb-CoPc repeatedly adsorbs on the growing and dissolving fronts of Li2O2and catalyze (or mediate) the positive electrode reactions. The results obtained here reveal the importance of an appropriate design for the soluble catalyst in rechargeable Li-air batteries to achieve high round-trip energy efficiency.

Electrochemical Study on Additive Effect of Porous V2O5 to Sulfur/Carbon Composite Cathode

The increase in the demand for clean and sustainable energy has prompted intense effort towards the realization of high-performance energy storage technologies. Among the many available energy storage technologies, lithium(Li)-ion batteries with Li-intercalation compounds as positive electrodes have achieved great success for use in portable electronic devices [1, 2]. A typical rechargeable Li-ion battery requires heavy host compounds (e.g., CoO2) to accommodate guest atoms (e.g., Li), which greatly limits its energy density to less than 210 Wh kg-1. On the other hand, a Li-sulfur (S) battery as a typical integration reaction battery system [4] may open a new horizon for electric vehicles. As the sulfur cathode has a theoretical specific capacity of 1672 mAh g-1, a Li-S battery can achieve an energy density of 2654 Wh kg-1 when combined with a lithium metal anode, which is 3-5-fold higher than those of current Li-ion batteries [5]. In addition, sulfur is a highly abundant element source on earth and is not geographically isolated [6], which may reduce the cost of cathode materials. However, Li-S batteries have serious problems [7-9], including low utilization of the active material and a poor cycle life because of the insulating property of sulfur and the high solubility of lithium polysulfides in organic electrolytes. To overcome the above-mentioned problems, much effort has been devoted to designing S-based cathodes, thus far. Various elegantly designed carbons have been studied for use as sulfur hosts to enhance the electronic conductivity of sulfur and trap polysulfides within a carbon framework simultaneously. However, carbon is an electrochemically inactive material in the integration reaction of Li-S batteries, and therefore its quantity in the electrode should be reduced as much as possible. Vanadium pentoxide (V2O5) is one of the most common cathode materials in the field of Li batteries and has a few advantages when used as an additive in sulfur cathodes. It is an electrochemically active material in the cut-off voltage range from 1.5 to 4 V, which closely matches that for sulfur cathodes (from 1.5 to 3 V), and it also positively contributes to the capacity of sulfur cathodes. In this study, S/Carbon/porousV2O5 nanocomposites were prepared by a novel synthesis route and their physical and electrochemical properties were further investigated. Porous V2O5 particles were firstly prepared by spray pyrolysis (SP) with NH4NO3 additive. The pore structure of obtained samples were analyzed by N2 adsorption-desorption isotherm measurements. The V2O5 particles with pore size less than 100 nm could be prepared at 500 ºC by SP with a 0.272 mol L-1 NH4NO3 additive, and the porous V2O5 electrode exhibited a first discharge capacity of 400 mAh g-1 at 20 mA g-1.The as-prepared porous V2O5 were packed with acetylene black and S at a targeted ration in a closed reactor. The reactor was heated at different temperatures ranging from 120 to 200 ºC. The effect of S content, heating temperature and heating time were investigated systematically. Figure 1 shows the cycle performance of the S/C/porous V2O5 composite electrode at a charge-discharge rate of 100 mA g-1. The cycle performance of the S/C composite electrode is also shown in the figure as a comparison. The S/C/porous V2O5 composite electrode exhibits a discharge capacity of 666 mAh g-1 at 50th cycles, while the S/C composite electrode shows a discharge capacity of 379 mAh g-1 at 50th cycles . As seen from this fact, the S/C/porous V2O5 composite electrode shows larger discharge capacities and better cycle performance than the S/C composite electrode. This fact indicate that the V2O5 additive to the S/C composite electrode leads to enhance its electrochemical performance.

Mobile technology habits:patterns of association among device usage, intertemporal preference, impulse control, and reward sensitivity.

Mobile electronic devices are playing an increasingly pervasive role in our daily activities. Yet, there has been very little empirical research investigating how mobile technology habits might relate to individual differences in cognition and affect. The research presented in this paper provides evidence that heavier investment in mobile devices is correlated with a relatively weaker tendency to delay gratification (as measured by a delay discounting task) and a greater inclination toward impulsive behavior (i.e., weaker impulse control, assessed behaviorally and through self-report) but is not related to individual differences in sensitivity to reward. Analyses further demonstrated that individual variation in impulse control mediates the relationship between mobile technology usage and delay of gratification. Although based on correlational results, these findings lend some backing to concerns that increased use of portable electronic devices could have negative impacts on impulse control and the ability to appropriately valuate delayed rewards.

Use of portable electronic devices in a hospital setting and their potential for bacterial colonization

Portable electronic devices are increasingly being used in the hospital setting. As with other fomites, these devices represent a potential reservoir for the transmission of pathogens. We conducted a convenience sampling of devices in 2 large medical centers to identify bacterial colonization rates and potential risk factors.

Distracted biking: a review of the current state-of-knowledge

Cyclists, much like drivers, have always been engaged in multi-tasking activities like using hand-held devices, listening to music, snacking, or reading while bicycling. While distracted drivers endanger themselves and other, distracted bikers, in general present more risk to themselves than to others. Distracted bicycling, however, has not received similar interventions to address safety related issues. This study reviewed the state-of-knowledge on policies, programs, data sources, and identified data collection opportunities and research needs. Literature review conducted in this study revealed only six [6] past studies that investigated the effect of distracted bicycling. The review also found that several agencies/organizations listed the use of portable electronic devices while cycling as unsafe behavior. Some of the agencies/organizations in the United States, Canada, Belgium, Bermuda, Germany, and New Zealand have implemented interventions to curb distracted bicycling such as education, awareness programs, and legislation. The majority of the legislation enacted ban the use of headphones or earphones in or on one or both ears and few ban hand-held phones while cycling. In addition to these, one law common to all U.S. states and District of Columbia restricts cyclists from carrying bundles, articles or objects that prevent them from keeping at least one hand on the handlebars which indirectly addresses distracted bicycling. Language: en

Ethylcellulose-coated polyolefin separators for lithium-ion batteries with improved safety performance

With the widely use in portable electronic devices and electric vehicles, the safety of lithium-ion battery has raised serious concerns, in which the thermal stability of separator plays an essential role in preventing thermal runaway reactions. The novelty of this work is to coat commercialized polyethylene (PE) separator and trilayer polypropylene/polyethylene/polypropylene (PP/PE/PP) separator with ethylcellulose (EC), a thermally stable and renewable biomass. The formation of the EC layer with high porosity is through a simple dipping and extracting process. The effects of the EC layer on thermal shrinkage, electrolyte wettability and cell performance are investigated. After coating, the thermal shrinkage of PE separator at shutdown and meltdown point is reduced from 20% to 9% and 42% to 23% respectively, while the drop of OCV under increasing temperature is also postponed from 130°C to 160°C. The electrolyte wettability of pristine trilayer PP/PE/PP separator is greatly improved, leading to increased capacity retention from 28% to 99% of the cell.

Mobile Health (mHealth) Approaches and Lessons for Increased Performance and Retention of Community Health Workers in Low- and Middle-Income Countries: A Review

BackgroundMobile health (mHealth) describes the use of portable electronic devices with software applications to provide health services and manage patient information. With approximately 5 billion mobile phone users globally, opportunities for mobile technologies to play a formal role in health services, particularly in low- and middle-income countries, are increasingly being recognized. mHealth can also support the performance of health care workers by the dissemination of clinical updates, learning materials, and reminders, particularly in underserved rural locations in low- and middle-income countries where community health workers deliver integrated community case management to children sick with diarrhea, pneumonia, and malaria.ObjectiveOur aim was to conduct a thematic review of how mHealth projects have approached the intersection of cellular technology and public health in low- and middle-income countries and identify the promising practices and experiences learned, as well as novel and innovative approaches of how mHealth can support community health workers.MethodsIn this review, 6 themes of mHealth initiatives were examined using information from peer-reviewed journals, websites, and key reports. Primary mHealth technologies reviewed included mobile phones, personal digital assistants (PDAs) and smartphones, patient monitoring devices, and mobile telemedicine devices. We examined how these tools could be used for education and awareness, data access, and for strengthening health information systems. We also considered how mHealth may support patient monitoring, clinical decision making, and tracking of drugs and supplies. Lessons from mHealth trials and studies were summarized, focusing on low- and middle-income countries and community health workers.ResultsThe review revealed that there are very few formal outcome evaluations of mHealth in low-income countries. Although there is vast documentation of project process evaluations, there are few studies demonstrating an impact on clinical outcomes. There is also a lack of mHealth applications and services operating at scale in low- and middle-income countries. The most commonly documented use of mHealth was 1-way text-message and phone reminders to encourage follow-up appointments, healthy behaviors, and data gathering. Innovative mHealth applications for community health workers include the use of mobile phones as job aides, clinical decision support tools, and for data submission and instant feedback on performance.ConclusionsWith partnerships forming between governments, technologists, non-governmental organizations, academia, and industry, there is great potential to improve health services delivery by using mHealth in low- and middle-income countries. As with many other health improvement projects, a key challenge is moving mHealth approaches from pilot projects to national scalable programs while properly engaging health workers and communities in the process. By harnessing the increasing presence of mobile phones among diverse populations, there is promising evidence to suggest that mHealth can be used to deliver increased and enhanced health care services to individuals and communities, while helping to strengthen health systems.