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"Jin, Wook"
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Robot, go bot! : a comic reader
A young girl makes so many demands on the robot she has constructed that he runs away.
Book
Role of JAK/STAT3 Signaling in the Regulation of Metastasis, the Transition of Cancer Stem Cells, and Chemoresistance of Cancer by Epithelial–Mesenchymal Transition
The JAK/STAT3 signaling pathway plays an essential role in various types of cancers. Activation of this pathway leads to increased tumorigenic and metastatic ability, the transition of cancer stem cells (CSCs), and chemoresistance in cancer via enhancing the epithelial–mesenchymal transition (EMT). EMT acts as a critical regulator in the progression of cancer and is involved in regulating invasion, spread, and survival. Furthermore, accumulating evidence indicates the failure of conventional therapies due to the acquisition of CSC properties. In this review, we summarize the effects of JAK/STAT3 activation on EMT and the generation of CSCs. Moreover, we discuss cutting-edge data on the link between EMT and CSCs in the tumor microenvironment that involves a previously unknown function of miRNAs, and also discuss new regulators of the JAK/STAT3 signaling pathway.
Journal Article
Regulation of BDNF-TrkB Signaling and Potential Therapeutic Strategies for Parkinson’s Disease
Brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase receptor type B (TrkB) are widely distributed in multiple regions of the human brain. Specifically, BDNF/TrkB is highly expressed and activated in the dopaminergic neurons of the substantia nigra and plays a critical role in neurophysiological processes, including neuro-protection and maturation and maintenance of neurons. The activation as well as dysfunction of the BDNF-TrkB pathway are associated with neurodegenerative diseases. The expression of BDNF/TrkB in the substantia nigra is significantly reduced in Parkinson’s Disease (PD) patients. This review summarizes recent progress in the understanding of the cellular and molecular roles of BNDF/TrkB signaling and its isoform, TrkB.T1, in Parkinson’s disease. We have also discussed the effects of current therapies on BDNF/TrkB signaling in Parkinson’s disease patients and the mechanisms underlying the mutation-mediated acquisition of resistance to therapies for Parkinson’s disease.
Journal Article
2D perovskite stabilized phase-pure formamidinium perovskite solar cells
Compositional engineering has been used to overcome difficulties in fabricating high-quality phase-pure formamidinium perovskite films together with its ambient instability. However, this comes alongside an undesirable increase in bandgap that sacrifices the device photocurrent. Here we report the fabrication of phase-pure formamidinium-lead tri-iodide perovskite films with excellent optoelectronic quality and stability. Incorporation of 1.67 mol% of 2D phenylethylammonium lead iodide into the precursor solution enables the formation of phase-pure formamidinium perovskite with an order of magnitude enhanced photoluminescence lifetime. The 2D perovskite spontaneously forms at grain boundaries to protect the formamidinium perovskite from moisture and suppress ion migration. A stabilized power conversion efficiency (PCE) of 20.64% (certified stabilized PCE of 19.77%) is achieved with a short-circuit current density exceeding 24 mA cm
−
2
and an open-circuit voltage of 1.130 V, corresponding to a loss-in-potential of 0.35 V, and significantly enhanced operational stability.
Utilizing mixed-cation-halide can improve stability of the formamidinium perovskite films and devices but sacrifices the photocurrent due to an increase in bandgap. Here Lee et al. introduced small amounts of 2D perovskite to obtain high efficiency and stability based on phase-pure formamidinium based perovskite.
Journal Article
Perovskite-polymer composite cross-linker approach for highly-stable and efficient perovskite solar cells
Manipulation of grain boundaries in polycrystalline perovskite is an essential consideration for both the optoelectronic properties and environmental stability of solar cells as the solution-processing of perovskite films inevitably introduces many defects at grain boundaries. Though small molecule-based additives have proven to be effective defect passivating agents, their high volatility and diffusivity cannot render perovskite films robust enough against harsh environments. Here we suggest design rules for effective molecules by considering their molecular structure. From these, we introduce a strategy to form macromolecular intermediate phases using long chain polymers, which leads to the formation of a polymer-perovskite composite cross-linker. The cross-linker functions to bridge the perovskite grains, minimizing grain-to-grain electrical decoupling and yielding excellent environmental stability against moisture, light, and heat, which has not been attainable with small molecule defect passivating agents. Consequently, all photovoltaic parameters are significantly enhanced in the solar cells and the devices also show excellent stability.
Defective grain boundaries of polycrystalline perovskite films are one of the major causes of the instability of the solar cell devices. Here Han et al. choose a polymer with proper molecular structure to crosslink the perovskite grains to greatly improve the device stability.
Journal Article
Activation of JUN in fibroblasts promotes pro-fibrotic programme and modulates protective immunity
The transcription factor JUN is highly expressed in pulmonary fibrosis. Its induction in mice drives lung fibrosis, which is abrogated by administration of anti-CD47. Here, we use high-dimensional mass cytometry to profile protein expression and secretome of cells from patients with pulmonary fibrosis. We show that
JUN
is activated in fibrotic fibroblasts that expressed increased CD47 and PD-L1. Using ATAC-seq and ChIP-seq, we found that activation of
JUN
rendered promoters and enhancers of CD47 and PD-L1 accessible. We further detect increased IL-6 that amplified
JUN
-mediated CD47 enhancer activity and protein expression. Using an in vivo mouse model of fibrosis, we found two distinct mechanisms by which blocking IL-6, CD47 and PD-L1 reversed fibrosis, by increasing phagocytosis of profibrotic fibroblasts and by eliminating suppressive effects on adaptive immunity. Our results identify specific immune mechanisms that promote fibrosis and suggest a therapeutic approach that could be used alongside conventional anti-fibrotics for pulmonary fibrosis.
Fibroblast contributions to lung fibrosis and in particular their crosstalk with immune cells in the lung are incompletely understood. Here, the authors show an overall immune suppressive environment transcriptionally controlled and maintained by fibroblasts in lung fibrosis with possible therapeutic implications.
Journal Article
Solid-phase hetero epitaxial growth of α-phase formamidinium perovskite
Conventional epitaxy of semiconductor films requires a compatible single crystalline substrate and precisely controlled growth conditions, which limit the price competitiveness and versatility of the process. We demonstrate substrate-tolerant nano-heteroepitaxy (NHE) of high-quality formamidinium-lead-tri-iodide (FAPbI
3
) perovskite films. The layered perovskite templates the solid-state phase conversion of FAPbI
3
from its hexagonal non-perovskite phase to the cubic perovskite polymorph, where the growth kinetics are controlled by a synergistic effect between strain and entropy. The slow heteroepitaxial crystal growth enlarged the perovskite crystals by 10-fold with a reduced defect density and strong preferred orientation. This NHE is readily applicable to various substrates used for devices. The proof-of-concept solar cell and light-emitting diode devices based on the NHE-FAPbI
3
showed efficiencies and stabilities superior to those of devices fabricated without NHE.
Though literature reports metal halide perovskite epitaxial growth on various substrates, controlling film growth for device applications remains a challenge. Here, the authors report kinetic-controlled growth of halide perovskite thin films on various substrates via layered perovskite templates.
Journal Article
Lead immobilization for environmentally sustainable perovskite solar cells
Lead halide perovskites are promising semiconducting materials for solar energy harvesting. However, the presence of heavy-metal lead ions is problematic when considering potential harmful leakage into the environment from broken cells and also from a public acceptance point of view. Moreover, strict legislation on the use of lead around the world has driven innovation in the development of strategies for recycling end-of-life products by means of environmentally friendly and cost-effective routes. Lead immobilization is a strategy to transform water-soluble lead ions into insoluble, nonbioavailable and nontransportable forms over large pH and temperature ranges and to suppress lead leakage if the devices are damaged. An ideal methodology should ensure sufficient lead-chelating capability without substantially influencing the device performance, production cost and recycling. Here we analyse chemical approaches to immobilize Pb
2+
from perovskite solar cells, such as grain isolation, lead complexation, structure integration and adsorption of leaked lead, based on their feasibility to suppress lead leakage to a minimal level. We highlight the need for a standard lead-leakage test and related mathematical model to be established for the reliable evaluation of the potential environmental risk of perovskite optoelectronics.
An analysis of chemical processes to immobilize lead from perovskite solar cells is presented, highlighting the need for a standard lead-leakage test and mathematical model to reliably evaluate the potential environmental risk of perovskite optoelectronics.
Journal Article
NiO as Hole Transporting Layer for Inverted Perovskite Solar Cells: A Study of X‐Ray Photoelectron Spectroscopy
Hygroscopic and acidic nature of organic hole transport layers (HTLs) insisted to replace it with metal oxide semiconductors due to their favorable charge carrier transport with long chemical stability. Apart from large direct bandgap and high optical transmittance, ionization energy in the range of −5.0 to −5.4 eV leads to use NiO as HTL due to good energetic matching with lead halide perovskites. Analyzing X‐ray photoelectron spectroscopic (XPS) data of NiO, it is speculated that p‐type conductivity is related to the NiOOH or Ni2O3 states in the structure and the electrical conductivity can be modified by altering the concentration of nickel or oxygen vacancies. However, it is difficult to separate the contribution from nonlocal screening, surface effect and the presence of vacancy induced Ni3+ ion due to very strong satellite structure in the Ni 2p XPS spectrum of NiO. Thus, an effective approach to analyze the NiO XPS spectrum is presented and the way to correlate the presence of Ni3+ with the conductivity results which will help to avoid overestimation in finding the oxygen‐rich/deficient conditions in NiO. The shoulder peak of Ni2p XPS spectrum is important to understand p‐type semiconducting behavior. Both the Ni 2p and O 1s XPS spectra shall be carefully recorded with fixed take‐off angle (and/or depending on take‐off angle) and compare results with transport measurements.
Journal Article
Polymer particles that switch shape in response to a stimulus
Particle engineering for biomedical applications has unfolded the roles of attributes such as size, surface chemistry, and shape for modulating particle interactions with cells. Recently, dynamic manipulation of such key properties has gained attention in view of the need to precisely control particle interaction with cells. With increasing recognition of the pivotal role of particle shape in determining their biomedical applications, we report on polymeric particles that are able to switch their shape in real time in a stimulus-responsive manner. The shape-switching behavior was driven by a subtle balance between polymer viscosity and interfacial tension. The balance between the two forces was modulated by application of an external stimulus chosen from temperature, pH, or chemical additives. The dynamics of shape switch was precisely controlled over minutes to days under physiological conditions. Shape-switching particles exhibited unique interactions with cells. Elliptical disk-shaped particles that are not phagocytosed by macrophages were made to internalize through shape switch, demonstrating the ability of shape-switchable particles in modulating interaction with cells.
Journal Article