Development of Limbal Epithelial Cell Carrier via Integration of Heterogeneous Collagen Matrices

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Scattering model for tetrapods with cylindrical arms

A scattering model for regular tetrapods, which are the endoskeleton structure of regular tetrahedrons, is presented. Since a tetrapod, unlike spheres and cylinders, is an anisotropic structure formed by four cylinders branching out from the centroid to the vertices of a tetrahedron, additional symmetry elements and random orientation must be accounted for to develop its scattering model. The scattering function of tetrapods was derived from the modification of the scattering model for cylinders and their structural regularity was simplified. Scattering intensity profiles and pair distance distribution functions were obtained by numerical calculation and compared with the experimental data from small angle X-ray measurements of CdSe tetrapod nanocrystals.OAIID:RECH_ACHV_DSTSH_NO:T201723361RECH_ACHV_FG:RR00200001ADJUST_YN:EMP_ID:A004677CITE_RATE:2.199FILENAME:Scattering model for tetrapods with cylindrical arms.pdfDEPT_NM:화학생물공학부EMAIL:[email protected]_YN:YFILEURL:https://srnd.snu.ac.kr/eXrepEIR/fws/file/e0d81a2c-d396-4d6c-bb15-5b2cb566482a/linkN

Development of Limbal Epithelial Cell Carrier via Integration of Heterogeneous Collagen Matrices

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Development of transplantable collagenous composite based on collagen compression process for treating limbal stem cell deficiency

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CdSe tetrapod interfacial layer for improving electron extraction in planar heterojunction perovskite solar cells

We demonstrate the improvement in the efficiency of planar heterojunction perovskite solar cells by employing cadmium selenide tetrapods (CdSe TPs) as an electron extraction layer. The insertion of the CdSe TP layer between the titanium oxide (TiO2) and perovskite film facilitates electron transfer at the TiO2/perovskite interface, as indicated by the significantly quenched steady-state photoluminescence of the perovskite film. Furthermore, we observed a conductivity enhancement of the perovskite film by introducing the CdSe TP layer. The combination of both effects induced by the TPs leads to enhancement in the carrier extraction as well as decreased recombination losses in the perovskite solar cells. As a result, an efficiency of 13.5% (1 sun condition) is achieved in the perovskite solar cells that incorporate the CdSe TP layer, which is 10% higher than that of the device without the CdSe TP layer.N

Growth and optical characteristics of high-quality ZnO thin films on graphene layers

We report the growth of high-quality, smooth, and flat ZnO thin films on graphene layers and their photoluminescence (PL) characteristics. For the growth of high-quality ZnO thin films on graphene layers, ZnO nanowalls were grown using metal-organic vapor-phase epitaxy on oxygen-plasma treated graphene layers as an intermediate layer. PL measurements were conducted at low temperatures to examine strong near-band-edge emission peaks. The full-width-at-half-maximum value of the dominant PL emission peak was as narrow as 4 meV at T = 11 K, comparable to that of the best-quality films reported previously. Furthermore, the stimulated emission of ZnO thin films on the graphene layers was observed at the low excitation energy of 180 kW/cm2 at room temperature. Their structural and optical characteristics were investigated using X-ray diffraction, transmission electron microscopy, and PL spectroscopy

Controlled spatial dispersion of CdSe tetrapod nanocrystals with amphiphilic block copolymer particles

We report, for the first time, a nanoscale control of the spatial distribution of semiconducting tetrapod (TP) nanocrystals within block copolymer particles. Polystyrene (PS) block copolymer (BCP)/CdSe TP nanocrystal hybrid particles were prepared by the nanoprecipitation of TP/BCP mixtures into methanol. The BCPs consisted of short, polar terminal block bearing methyl disulfide anchoring moiety which serves both to bind to CdSe TP surfaces as well as to drive self-assembly during nanoprecipitation into polar solvent systems. The resulting BCP/TP hybrid particles showed various spatial distribution and the number density of TPs with respect to individual polymer particles depending on the degree of polymerization of the block copolymer as well as the nature of the solvent in which nanoprecipitation was done. (C) 2016 Elsevier Ltd. All rights reserved.N

Assemblies of Colloidal CdSe Tetrapod Nanocrystals with Lengthy Arms for Flexible Thin-Film Transistors

Herein, we report unique features of the assemblies of tetrapod-shaped colloidal nanocrystals (TpNCs) with lengthy arms applicable to flexible thin-film transistors. Due to the extended nature of tetrapod geometry, films made of the TpNC assemblies require reduced numbers of inter-NC hopping for the transport of charge carriers along a given channel length; thus, enhanced conductivity can be achieved compared to those made of typical spherical NCs without arms. Moreover, electrical conduction through the assemblies is tolerant against mechanical bending because interconnections between TpNCs can be well-preserved under bending. Interestingly, both the conductivity of the assemblies and their mechanical tolerance against bending are improved with an increase in the length of tetrapod arms. The arm length-dependency was demonstrated in a series of CdSe TpNC assemblies with different arm lengths (<i>l</i> = 0–90 nm), whose electrical conduction was modulated through electrolyte gating. From the TpNCs with the longest arm length included in the study (<i>l</i> = 90 nm), the film conductivity as high as 20 S/cm was attained at 3 V of gate voltage, corresponding to electron mobility of >10 cm²/(V s) even when evaluated conservatively. The high channel conductivity was retained (∼90% of the value obtained from the flat geometry) even under high bending (bending radius = 5 mm). The results of the present study provide new insights and guidelines for the use of colloidal nanocrystals in solution-processed flexible electronic device applications

Direct Observation for Distinct Behaviors of Gamma‐Ray Irradiation‐Induced Subgap Density‐of‐States in Amorphous InGaZnO TFTs by Multiple‐Wavelength Light Source

Abstract The amorphous In─Ga─Zn─O (a‐IGZO) thin film transistors (TFTs) have attracted attention as a cell transistor for the next generation DRAM architecture because of its low leakage current, high mobility, and the back‐end‐of‐line (BEOL) compatibility that enables monolithic 3D (M3D) integration. IGZO‐based electronic devices used in harsh environments such as radiation exposure can be vulnerable, resulting in functional failure. Here, the behavior of subgap density‐of‐states (DOS) over full subgap range according to the impactful gamma‐ray irradiation in a‐IGZO TFTs is investigated by employing DC current–voltage (I−V) data with multiple‐wavelength light sources. To understand the origins of the radiation effect, IGZO films have been also analyzed by x‐ray photoelectron spectroscopy (XPS). Considering in‐depth electrical and chemical analysis, the unexpected increase of subthreshold leakage current caused by total ionizing dose (TID) is strongly correlated with newly discovered deep‐donor states (gDDγ(E)) at the specific energy level. In particular, oxygen vacancies caused by the gamma‐ray irradiation give rise to undesirable electrical characteristics such as hysteresis effect and negative shift of threshold voltage (VT). Furthermore, the TCAD simulation results based on DOS model parameters are found to exhibit good agreement with experimental data and plausible explanation including (gDDγ(E))