In this communication, we successfully synthesized a new SnO(2) nanoarchitecture: extremely thin sheets, with minimum thicknesses of 1.5-3.0 nm. The products were prepared through a facile hydrothermal treatment using tin dichloride as the precursor. Planar or scrolled SnO(2) sheets were carefully examined by transmission electron microscopy. The assemblies of these sheets have a high BET surface area of 180.3 m(2)/g and extraordinarily large pore volume of 1.028 cm(3)/g. They also exhibit a high lithium storage capacity and excellent cyclability due to its nanometer-sized frame and breathable characteristic.
We successfully synthesized large-scale and highly pure
ultrathin
SnO2 nanosheets (NSs), with a minimum thickness in the
regime of ca. 2.1 nm as determined by HRTEM and in good agreement
with XRD refinements and AFM height profiles. Through TEM and HRTEM
observations on time-dependent samples, we found that the as-prepared
SnO2 NSs were assembled by “oriented attachment”
of preformed SnO2 nanoparticles (NPs). Systematic trials
showed that well-defined ultrathin SnO2 NSs could only
be obtained under appropriate reaction time, solvent, additive, precursor
concentration, and cooling rate. A certain degree of nonstoichiometry
appears inevitable in the well-defined SnO2 NSs sample.
However, deviations from the optimal synthetic parameters give rise
to severe nonstoichiometry in the products, resulting in the formation
of Sn3O4 or SnO. This finding may open new accesses
to the fundamental investigations of tin oxides as well as their intertransition
processes. Finally, we investigated the lithium-ion storage of the
SnO2 NSs as compared to SnO2 hollow spheres
and NPs. The results showed superior performance of SnO2 NSs sample over its two counterparts. This greatly enhanced Li-ion
storage capability of SnO2 NSs is probably resulting from
the ultrathin thicknesses and the unique porous structures: the nanometer-sized
networks provide negligible diffusion times of ions thus faster phase
transitions, while the “breathable” interior porous
structure can effectively buffer the drastic volume changes during
lithiation and delithiation reactions.
In December 2015 the Australian state and territory governments endorsed the ‘National STEM School Education Strategy 2016–2026’. Since then, the individual jurisdictions have released their own STEM education strategies that aim to improve student STEM capabilities and aspirations. This paper analyses the various Australian STEM education strategies in relation to six themes informed by research into effective STEM education: STEM capabilities; STEM dispositions; STEM educational practices; Equity; Trajectories; and Educator capacities. The analysis shows that Australia’s STEM education strategies focus on actions aimed at building student STEM capabilities, particularly through inquiry and problem-based learning, and enhancing educator capacity. The strategies recognise student STEM learning trajectories and pay particular attention to the importance of early childhood STEM education, as well as the ways in which students’ potential career pathways might be influenced. However, less emphasis is placed on supporting key transitions in STEM education, developing student STEM dispositions, and addressing equity issues in STEM.
See Huang and Gitler (doi:) for a scientific commentary on this article.Small molecule drugs that can reduce levels of the mutant huntingtin protein (mHTT) are sought for the treatment of Huntington’s disease. Song et al. demonstrate that deleting Gpr52, or inhibiting Gpr52 protein function with a novel small molecule antagonist, reduces mHTT levels and rescues Huntington’s disease-associated phenotypes in cellular and mouse models.
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