In this work, we reported successful synthesis of SnO sub(2) nanocubes and nanospheres via a facile hydrothermal technique. The as-obtained SnO sub(2) nanostructures have been characterized by X-ray ...diffraction and field-emission scanning electron microscopy. The formation mechanism of aforementioned SnO sub(2) nanostructures has been proposed in detail, especially SnO sub(2) nanaocubes, which has been systematically investigated by varying the reaction time and the surfactant SDS play a key role in growth process of nanocubes. Furthermore, the gas sensing properties of as-prepared SnO sub(2) nanostructures have been tested towards ethanol. Interestingly, it is noted that gas sensing performance of nanocubes are superior to nanospheres, which certified that the gas sensing properties can be enhanced by controlling the morphologies and the SnO sub(2) nanocubes maybe a promising candidate based materials in the fields of gas sensors.
Morphologies frequently play a critical role in determining the properties of nanomaterials. In current researches, we successfully synthesized varieties of SnO sub(2) nanostructures from 1D to 3D ...via a facile hydrothermal method. The as-obtained samples were characterized by X-ray diffraction and scanning electron microscopy. Then the plausible growth mechanism are proposed in detail. Furthermore, PEG and CO(NH sub(2)) sub(2) may have an effect on the formation of 1D and 2D nanostructures of SnO sub(2) as aggregation and template, respectively. The gas sensing properties of SnO sub(2) nanostructures from 1D to 3D toward ethanol were investigated. Surprisingly, we noticed that SnO sub(2) nanosheets show the highest gas sensing response while the nanospheres is opposite, which provided a substantial promising candidate of gas sensors and further indicated that gas sensing properties can be enhanced by tailoring the morphologies of nanomaterials in practical application.
MoS2 holds great promise as high‐rate electrode for lithium‐ion batteries since its large interlayer can allow fast lithium diffusion in 3.0–1.0 V. However, the low theoretical capacity (167 mAh g−1) ...limits its wide application. Here, by fine tuning the lithiation depth of MoS2, we demonstrate that its parent layered structure can be preserved with expanded interlayers while cycling in 3.0–0.6 V. The deeper lithiation and maintained crystalline structure endows commercially micrometer‐sized MoS2 with a capacity of 232 mAh g−1 at 0.05 A g−1 and circa 92 % capacity retention after 1000 cycles at 1.0 A g−1. Moreover, the enlarged interlayers enable MoS2 to release a capacity of 165 mAh g−1 at 5.0 A g−1, which is double the capacity obtained under 3.0–1.0 V at the same rate. Our strategy of controlling the lithiation depth of MoS2 to avoid fracture ushers in new possibilities to enhance the lithium storage of layered transition‐metal dichalcogenides.
Durch Feinabstimmung der Lithiierungstiefe von MoS2 kann die kristalline Schichtstruktur beim Zyklisieren (3.0–0.6 V gegen Li+/Li) bewahrt werden, einhergehend mit einer Vergrößerung des Abstands zwischen den Schichten. Dies ermöglicht ein stabiles Zyklisieren von kommerziellem μm‐großem MoS2 mit höherer Kapazität und Lade/Entlade‐Rate; man erhält damit eine vielversprechende Anode für schnellladende Lithium‐Ionen‐Batterien.
Abstract
MoS
2
holds great promise as high‐rate electrode for lithium‐ion batteries since its large interlayer can allow fast lithium diffusion in 3.0–1.0 V. However, the low theoretical capacity ...(167 mAh g
−1
) limits its wide application. Here, by fine tuning the lithiation depth of MoS
2
, we demonstrate that its parent layered structure can be preserved with expanded interlayers while cycling in 3.0–0.6 V. The deeper lithiation and maintained crystalline structure endows commercially micrometer‐sized MoS
2
with a capacity of 232 mAh g
−1
at 0.05 A g
−1
and circa 92 % capacity retention after 1000 cycles at 1.0 A g
−1
. Moreover, the enlarged interlayers enable MoS
2
to release a capacity of 165 mAh g
−1
at 5.0 A g
−1
, which is double the capacity obtained under 3.0–1.0 V at the same rate. Our strategy of controlling the lithiation depth of MoS
2
to avoid fracture ushers in new possibilities to enhance the lithium storage of layered transition‐metal dichalcogenides.
Domestic yaks (Bos grunniens) provide meat and other necessities for Tibetans living at high altitude on the Qinghai-Tibetan Plateau and in adjacent regions. Comparison between yak and the closely ...related low-altitude cattle (Bos taurus) is informative in studying animal adaptation to high altitude. Here, we present the draft genome sequence of a female domestic yak generated using Illumina-based technology at 65-fold coverage. Genomic comparisons between yak and cattle identify an expansion in yak of gene families related to sensory perception and energy metabolism, as well as an enrichment of protein domains involved in sensing the extracellular environment and hypoxic stress. Positively selected and rapidly evolving genes in the yak lineage are also found to be significantly enriched in functional categories and pathways related to hypoxia and nutrition metabolism. These findings may have important implications for understanding adaptation to high altitude in other animal species and for hypoxia-related diseases in humans.
Lithium (Li) metal is an excellent anode of Li ion batteries because of its high theoretical capacity and the low redox potential compared to other anodes. However, the uncontrollable growth of Li ...dendrites still incurs serious safety issues and poor electrochemical performances, leading to its limited practical application. An oxygen and boron codoped honeycomb carbon skeleton (OBHcCs) is reported and a stable Li metal‐based anode is realized. It can be coated on a copper foil substrate to be used as a current collector for a dendrite‐free Li metal anode. OBHcCs effectively reduces the local current density owing to the high surface area and inhibits Li dendrite growth, which is explored by scanning electron microscopy and an X‐ray photoelectron spectra depth profile. The abundant lithiophilic oxygen and boron‐containing functional groups reduce the potential barrier of nucleation and lead to the homogeneous Li ions flux as confirmed by the density functional theories. Therefore, the Li metal anode based on OBHcCs (OBHcCs@Li) stably runs for 700 h in a symmetric cell with a Li stripping capacity of 1 mAh cm−2 at 1 mA cm−2. Furthermore, the OBHcCs@Li|LiFePO4 full cell shows a good capacity retention of 84.6% with a high coulombic efficiency of 99.6% at 0.5 C for 500 cycles.
An oxygen and boron codoped honeycomb carbon skeleton allows lithium to grow along the skeleton, guiding heterogeneous nucleation and uniform deposition of lithium. In addition, it maintains the structural integrity after lithium exfoliation. The abundant lithiophilic oxygen and boron‐containing functional groups, such as BCO2 and BC2O bonds, enhance the adsorption of lithium (Li)‐ion for uniform Li‐ion transport flux.
Extracellular vesicles from adipose derived stem cells (ADSCs‐EVs) have shown immunomodulation and anti‐photoaging effects; however, the skin barrier prevents their absorption via skin. Meanwhile, ...microneedle (MN) is a widely used and minimally invasive tool for dermal delivery of drugs, it also has neocollagenesis effect by creating tiny injuries and initiating wound healing process. To investigate the effect of MN combined with ADSCs‐EVs on skin aging, photoaging in SKH‐1 mice was induced by chronic exposure to ultraviolet radiation. Then the mice were treated following a split‐dorsal scheme, in which one side had MN alone or MN + EVs treatment and the other side was left untreated. For the side treated with MN alone or MN + EVs, the epidermal thickness was decreased and the skin barrier function was enhanced compared with the untreated side. However, MN + EVs group showed the least wrinkles, the highest collagen density and the most organized collagen fibers among the three groups. The level of CD11b + cell infiltration was lower in MN + EVs group than that in the MN group at 3 day after the treatment. These results indicated that MN treatment alone could improve epidermal structure and function of photoaging skin, and a combination with ADSCs‐EVs would accelerate the restoration of inflammation caused by MN and improve the content of collagen. In all, this study indicated that a combination of MN and topical applied ADSCs‐EVs was a feasible and safe strategy to ameliorate photoaging, providing a new avenue for safe administration of EVs.
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