Carbon-based silicon nanohybrid anode materials for rechargeable lithium ion batteries

Silicon has demonstrated great potential as anode materials for next-generation high-energy density rechargeable lithium ion batteries. However, its poor mechanical integrity needs to be improved to achieve the required cycling stability. Nano-structured silicon has been used to prevent the mechanical failure caused by large volume expansion of silicon. Unfortunately, pristine silicon nanostructures still suffer from quick capacity decay due to several reasons, such as formation of solid electrolyte interphase, poor electrical contact and agglomeration of nanostructures. Recently, increasing attention has been paid to exploring the possibilities of hybridization with carbonaceous nanostructures to solve these problems. In this review, the recent advances in the design of carbon-silicon nanohybrid anodes and existing challenges for the development of high-performance lithium battery anodes are briefly discussed.

Sleep and self-regulation from birth to 7 years: A retrospective study of children with and without ADHD at 8-9 years

Objective To examine mean level differences, and longitudinal and reciprocal relations among behavioral sleep problems, emotional dysregulation, and attentional regulation across early childhood for children with and without ADHD at 8-9 years. Method This study used data from Growing Up in Australia: The Longitudinal Study of Australian Children (LSAC) – Infant Cohort (n = 4109 analyzed). Children with and without ADHD were identified at age 8-9 years via parent-report of ADHD diagnosis and the 5-item Inattention-Hyperactivity subscale from the Strengths and Difficulties Questionnaire. Maternal report of child sleep problems and self-regulation was collected at 0-1, 2-3, 4-5 and 6-7 years of age. ANOVA was used to compare mean level differences in sleep problems, emotional and attentional regulation by ADHD group. Longitudinal structural equation modeling examined the relations among sleep and self-regulation across time in children with and without ADHD. Results Children with ADHD had persistently elevated levels of sleep problems (from infancy) and emotional and attentional dysregulation compared to controls (from 2-3 years of age). Sleep problems, emotional dysregulation, and attentional regulation were stable over time for both groups. Sleep problems were associated with greater emotional dysregulation two years later from 2-3 years of age for both groups, which in turn was associated with poorer attentional regulation. There was no direct relationship between sleep problems and later attentional regulation. Conclusion Sleep problems in children with and without ADHD are associated with emotional dysregulation, which in turn contributes to poorer attentional functioning. This study highlights the importance of assessing and managing sleep problems in young children.

Determination of the kallikrein-related peptidase 7 degradome and Transciptome in ovarian cancer

Ovarian cancer is the leading cause of cancer-related death in women, and the need for curative treatments is urgent. This study characterised an enzyme associated with the most lethal form of ovarian cancer, showing this enzyme to be a promising therapeutic target. Fifteen novel protein targets and key signalling pathways were determined to be regulated by this enzyme, kallikrein-related peptidase 7, in the ovarian tumour microenvironment, highlighting its involvement in cancer progression. Inhibition of this enzyme may be a useful therapeutic option to improve the life expectancy of women suffering from this cancer.

Editorial of "International Journal of Critical Indigenous Studies, Volume 7, Number 1, 2014"

This edition testifies to the broad international reach of the journal, with contributions variously concerned with Arctic Indigenous communities, the Métis of Canada, Native Hawaiians and Māori of Aotearoa (New Zealand). Two articles stress the need to work collaboratively and respectfully with Indigenous populations whilst conducting research. The first, by Gwen Healey, notes the increased interest in health research in the Arctic, particularly with Inuit populations. Healy seeks to add to the growing body of literature concerned with Indigenous ways of knowing by highlighting Inuit concepts that inform an effective Arctic research model. The second, by primary author Peter Hutchinson and a range of co-contributors, highlights the ways in which Métis collaborators working in health developed a participatory Indigenous research method that was unique in that it foregrounded Métis relationships and relationality. In so doing, the researchers were able to give substance to otherwise staid policy statements about the need for good ethical research conduct.

Editorial of "International Journal of Critical Indigenous Studies, Volume 7, Number 2, 2014"

This edition scales the merlons and embrasures that mark the epistemological barriers that contemporary colonising power continually puts in place. Each article harnesses a critical Indigenous perspective in order to challenge conservative approaches or positions, be they concerned with reconciliation, Indigenous-led research, research tools or the nature of Aboriginal being. The first article, by Barry Judd and Emma Barrow, examines reconciliation discourse within the higher education sector and highlights the ways a normative Anglo-Australian identity militates against genuine ‘whitefella’ attempts to ‘reconcile’. The authors stress the importance of inclusive, institutional practice that serves to decentre Anglo-centrism and which, in turn, brings Indigenous peoples more fully into the fold of Australian university life.

Editorial of "Student Success, volume 7, issue 1"

Welcome to Volume 7 of Student Success. This editorial has two parts: The first part maintains the “doing things differently” tradition, making readers aware by chronicling the publishing of the journal in an open access (OA) forum. Future editorials will briefly discuss other aspects and issues pertaining to the new scholarly publishing landscape that this journal adheres to, such as: Creative Commons Licencing; ORCID IDs; considerations of new peer review models and importantly; measuring research impact in OA publishing. The second part presents the usual editorial summary of the content of this issue.

Evaluation of a 7-gene genetic profile for athletic endurance phenotype in Ironman championship triathletes

Polygenic profiling has been proposed for elite endurance performance, using an additive model determining the proportion of optimal alleles in endurance athletes. To investigate this model’s utility for elite triathletes, we genotyped seven polymorphisms previously associated with an endurance polygenic profile (ACE Ins/Del, ACTN3 Arg577Ter, AMPD1 Gln12Ter, CKMM 1170bp/985+185bp, HFE His63Asp, GDF8 Lys153Arg and PPARGC1A Gly482Ser) in a cohort of 196 elite athletes who participated in the 2008 Kona Ironman championship triathlon. Mean performance time (PT) was not significantly different in individual marker analysis. Age, sex, and continent of origin had a significant influence on PT and were adjusted for. Only the AMPD1 endurance-optimal Gln allele was found to be significantly associated with an improvement in PT (model p=5.79 x 10-17, AMPD1 genotype p=0.01). Individual genotypes were combined into a total genotype score (TGS); TGS distribution ranged from 28.6 to 92.9, concordant with prior studies in endurance athletes (mean±SD: 60.75±12.95). TGS distribution was shifted toward higher TGS in the top 10% of athletes, though the mean TGS was not significantly different (p=0.164) and not significantly associated with PT even when adjusted for age, sex, and origin. Receiver operating characteristic curve analysis determined that TGS alone could not significantly predict athlete finishing time with discriminating sensitivity and specificity for three outcomes (less than median PT, less than mean PT, or in the top 10%), though models with the age, sex, continent of origin, and either TGS or AMPD1 genotype could. These results suggest three things: that more sophisticated genetic models may be necessary to accurately predict athlete finishing time in endurance events; that non-genetic factors such as training are hugely influential and should be included in genetic analyses to prevent confounding; and that large collaborations may be necessary to obtain sufficient sample sizes for powerful and complex analyses of endurance performance.

Carbon-coated hierarchical SnO2 hollow spheres for lithium ion batteries

Hierarchical SnO2 hollow spheres self-assembled from nanosheets were prepared with and without carbon coating. The combination of nanosized architecture, hollow structure, and a conductive carbon layer endows the SnO2-based anode with improved specific capacity and cycling stability, making it more promising for use in lithium ion batteries.

Atomic layer-by-layer Co3O4/graphene composite for high performance lithium-ion batteries

An "atomic layer-by-layer" structure of Co3O4/graphene is developed as an anode material for lithium-ion batteries. Due to the atomic thickness of both the Co3O4 nanosheets and the graphene, the composite exhibits an ultrahigh specific capacity of 1134.4 mAh g-1 and an ultralong life up to 2000 cycles at 2.25 C, far beyond the performances of previously reported Co3O4/C composites.

3D Fe2(MoO4)3 microspheres with nanosheet constituents as high-capacity anode materials for lithium-ion batteries

Three-dimensional (3D) Fe2(MoO4)3 microspheres with ultrathin nanosheet constituents are first synthesized as anode materials for the lithium-ion battery. It is interesting that the single-crystalline nanosheets allow rapid electron/ion transport on the inside, and the high porosity ensures fast diffusion of liquid electrolyte in energy storage applications. The electrochemical properties of Fe2(MoO4)3 as anode demonstrates that 3D Fe2(MoO4)3 microspheres deliver an initial capacity of 1855 mAh/g at a current density of 100 mA/g. Particularly, when the current density is increased to 800 mA/g, the reversible capacity of Fe2(MoO4)3 anode still arrived at 456 mAh/g over 50 cycles. The large and reversible capacities and stable charge–discharge cycling performance indicate that Fe2(MoO4)3 is a promising anode material for lithium battery applications. Graphical abstract The electrochemical properties of Fe2(MoO4)3 as anode demonstrates that 3D Fe2(MoO4)3 microspheres delivered an initial capacity of 1855 mAh/g at a current density of 100 mA/g. When the current density was increased to 800 mA/g, the Fe2(MoO4)3 still behaved high reversible capacity and good cycle performance.

Dual yolk-shell structure of carbon and silica-coated silicon for high-performance lithium-ion batteries

Silicon batteries have attracted much attention in recent years due to their high theoretical capacity, although a rapid capacity fade is normally observed, attributed mainly to volume expansion during lithiation. Here, we report for the first time successful synthesis of Si/void/SiO2/void/C nanostructures. The synthesis strategy only involves selective etching of SiO2 in Si/SiO2/C structures with hydrofluoric acid solution. Compared with reported results, such novel structures include a hard SiO2-coated layer, a conductive carbon-coated layer, and two internal void spaces. In the structures, the carbon can enhance conductivity, the SiO2 layer has mechanically strong qualities, and the two internal void spaces can confine and accommodate volume expansion of silicon during lithiation. Therefore, these specially designed dual yolk-shell structures exhibit a stable and high capacity of 956 mA h g−1 after 430 cycles with capacity retention of 83%, while the capacity of Si/C core-shell structures rapidly decreases in the first ten cycles under the same experimental conditions. The novel dual yolk-shell structures developed for Si can also be extended to other battery materials that undergo large volume changes.

A germanium/single-walled carbon nanotube composite paper as a free-standing anode for lithium-ion batteries

Paper-like free-standing germanium (Ge) and single-walled carbon nanotube (SWCNT) composite anodes were synthesized by the vacuum filtration of Ge/SWCNT composites, which were prepared by a facile aqueous-based method. The samples were characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Electrochemical measurements demonstrate that the Ge/SWCNT composite paper anode with the weight percentage of 32% Ge delivered a specific discharge capacity of 417 mA h g-1 after 40 cycles at a current density of 25 mA g-1, 117% higher than the pure SWCNT paper anode. The SWCNTs not only function as a flexible mechanical support for strain release, but also provide excellent electrically conducting channels, while the nanosized Ge particles contribute to improving the discharge capacity of the paper anode.

In-situ one-step hydrothermal synthesis of a lead germanate-graphene composite as a novel anode material for lithium-ion batteries

Lead germanate-graphene nanosheets (PbGeO3-GNS) composites have been prepared by an efficient one-step, in-situ hydrothermal method and were used as anode materials for Li-ion batteries (LIBs). The PbGeO3 nanowires, around 100–200 nm in diameter, are highly encapsulated in a graphene matrix. The lithiation and de-lithiation reaction mechanisms of the PbGeO3 anode during the charge-discharge processes have been investigated by X-ray diffraction and electrochemical characterization. Compared with pure PbGeO3 anode, dramatic improvements in the electrochemical performance of the composite anodes have been obtained. In the voltage window of 0.01–1.50 V, the composite anode with 20 wt.% GNS delivers a discharge capacity of 607 mAh g−1 at 100 mA g−1 after 50 cycles. Even at a high current density of 1600 mA g−1, a capacity of 406 mAh g−1 can be achieved. Therefore, the PbGeO3-GNS composite can be considered as a potential anode material for lithium ion batteries.

Kinetics and mechanism of hot corrosion of γ-Y 2Si 2O 7 in thin-film Na 2SO 4 molten salt

γ-Y 2Si 2O 7 is a promising candidate material both for hightemperature structural applications and as an environmental/thermal barrier coating material due to its unique properties such as high melting point, machinability, thermal stability, low linear thermal expansion coefficient (3.9×10 -6/K, 200°-1300°C), and low thermal conductivity (<3.0 W/ṁK above 300°C). The hot corrosion behavior of γ-Y 2Si 2O 7 in thin-film molten Na 2SO 4 at 850°-1000°C for 20 h in flowing air was investigated using a thermogravimetric analyzer (TGA) and a mass spectrometer (MS). γ-Y 2Si 2O 7 exhibited good resistance against Na 2SO 4 molten salt. The kinetic curves were well fitted by a paralinear equation: the linear part was caused by the evaporation of Na2SO4 and the parabolic part came from gas products evolved from the hotcorrosion reaction. A thin silica film formed under the corrosion scale was the key factor for retarding the hot corrosion. The apparent activation energy for the corrosion of γ-Y 2Si 2O 7 in Na 2SO 4 molten salt with flowing air was evaluated to be 255 kJ/mol.