7 research outputs found
Nitrogen/sulfur dual-doping of reduced graphene oxide harvesting hollow ZnSnS3 nano-microcubes with superior sodium storage
Bimetallic sulfides have exhibited promising applications in advanced sodium-ion batteries (SIBs) due to their relatively high electronic conductivity and electrochemical activity. In this study, for the first time, the N/S dual-doped reduced graphene oxide (rGO) encapsulating hollow ZnSnS3 nano-microcubes (N/S-rGO@ZnSnS3) is designed to improve the sluggish reaction kinetics, poor cycling stability and unsatisfactory rate capability of metal sulfides. To examine this design, the cycling stability and rate capability of the desired anode material is studied in detail. It is found that N/S-rGO@ZnSnS3 hybrid delivers a high discharge capacity of 501.7 mAh gâ1 after 100 cycles at 0.1 A gâ1, and a reversible capacity of 290.7 mAh gâ1 after 500 cycles at 1.0 A gâ1 with a capacity fading of 0.06% per cycle. The cycling stability as well as rate capability of N/S-rGO@ZnSnS3 are superior to those of the pristine hollow ZnSnS3 cubes/un-doped rGO composite. It is convinced that the electrode performance is strongly rooted in its structural conformation. Furthermore, the structural evolutions of ZnSnS3 reactions with sodium are revealed by in situ X-ray diffraction combined with ex situ X-ray photoelectron spectroscopy, which provides a valuable revelation for the understanding of reaction mechanism toward bimetallic sulfides and beyond
Image Processing for Laser Imaging Using Adaptive Homomorphic Filtering and Total Variation
Laser active imaging technology has important practical value and broad application prospects in military fields such as target detection, radar reconnaissance, and precise guidance. However, factors such as uneven laser illuminance, atmospheric backscatter, and the imaging system itself will introduce noise, which will affect the quality of the laser active imaging image, resulting in image contrast decline and blurring image edges and details. Therefore, an image denoising algorithm based on homomorphic filtering and total variation cascade is proposed in this paper, which strives to reduce the noise while retaining the edge features of the image to the maximum extent. Firstly, the image type is determined according to the characteristics of the laser image, and then the speckle noise in the low-frequency region is suppressed by adaptive homomorphic filtering. Finally, the image denoising method of minimizing the total variation is adopted for the impulse noise and Gaussian noise. Experimental results show that compared with separate homomorphic filtering, total variation filtering, and median filtering, the proposed algorithm significantly improves the contrast, retains edge details, achieves the expected effect. It can better adjust the image brightness and is beneficial for subsequent processing
All-Solution-Processed Cu2ZnSnS4 Solar Cells with Self-Depleted Na2S Back Contact Modification Layer
The thinâfilm photovoltaic material Cu2ZnSnS4 (CZTS) has drawn worldwide attention in recent years due to its earthâabundant, nontoxic element constitution, and remarkable photovoltaic performance. Although stateâofâtheâart power conversion efficiency is achieved by hydrazineâbased methods, effort to fabricate such devices in a high throughput, environmentalâfriendly way is still highlydesired. Here a hydrazineâfree allâsolutionâprocessed CZTS solar cell with Na2S selfâdepleted back contact modification layer for the first time is demonstrated, using a ballâmilled CZTS as light absorber, lowâtemperature solutionâprocessed ZnO electronâtransport layer as well as silverânanowire transparent electrode. The inserting of Na2S selfâdepleted layer is proven to effectively stabilize the CZTS/Mo interface by eliminating a detrimental phase segregation reaction between CZTS and Moâcoated soda lime glass, thus leading to a better crystallinity of CZTS light absorbing layer, enhanced carrier transportation at CZTS/Mo interface as well as a smaller series resistance. Furthermore, the selfâdepletion feature of the Na2S modification layer also averts holeâtransportation barrier within the devices. The results show the vital importance of interfacial engineering for these CZST devices and the Na2S interface layer can be extended to other optoelectronic devices using Mo contact
Direct induction of functional neuronal cells from fibroblast-like cells derived from adult human retina
Obtaining and manipulating neuronal cells are critical for neural biology basic mechanism studies and translational applications. Recent advances in protocol development and mechanism dissections have made direct induction of neuronal cells from other somatic cells (iN) a promising strategy for such purposes. In this study, we established a protocol to expand a population of fibroblast-like cells from adult human retinal tissues, which can be reprogrammed into iNs by forced expression of neurogenic transcription factors. Interestingly, the combination of Ascl1, Brn2, Myt1l, and NeuroD1 transcription factors, which has been demonstrated to be sufficient to reprogram human embryonic and dermal fibroblasts into iNs, failed to reprogram the fibroblast-like cells from human retinas into iNs. Instead, supplementing Ascl1 with Pax6 sufficed to convert the cells into iNs, which exhibited a typical neuronal morphology, expressed neural marker genes, displayed active and passive neuronal membrane activities, and made synaptic communications with other neurons. Moreover, iNs converted from retina-derived fibroblast-like cells contained high ratios of Îł-Aminobutyric acid- (GABA-) and tyrosine hydroxylase- (TH-) positive neurons. Thus, the present study proposes a protocol that makes use of discarded retinal tissues from eye banks for iN generation, and suggests that different sources of somatic cells require different iN induction recipes and may also affect the iN subtype outputs. Our study may also facilitate the future development of methods to convert resident cells in situ into retinal neurons for treating retinal degeneration disease purpose
Controllably Designed âVice-Electrodeâ Interlayers Harvesting High Performance Lithium Sulfur Batteries
An
interlayer has been regarded as a promising mediator to prolong the
life span of lithium sulfur batteries because its excellent absorbability
to soluble polysulfide efficiently hinders the shuttle effect. Herein,
we designed various interlayers and understand the working mechanism
of an interlayer for lithium sulfur batteries in detail. It was found
that the electrochemical performance of a S electrode for an interlayer
located in cathode side is superior to the pristine one without interlayers.
Surprisingly, the performance of the S electrode for an interlayer
located in anode side is poorer than that of pristine one. For comparison,
glass fibers were also studied as a nonconductive interlayer for lithium
sulfur batteries. Unlike the two interlayers above, these nonconductive
interlayer did displays significant capacity fading because polysulfides
were adsorbed onto insulated interlayer. Thus, the nonconductive interlayer
function as a âdead zoneâ upon cycling. Based on our
findings, it was for the first time proposed that a controllably optimized
interlayer, with electrical conductivity as well as the absorbability
of polysulfides, may function as a âvice-electrodeâ
of the anode or cathode upon cycling. Therefore, the cathodic conductive
interlayer can enhance lithium sulfur battery performance, and the
anodic conductive interlayer may be helpful for the rational design
of 3D networks for the protection of lithium metal