Structural Modification of Organic Materials for Energy Harvesting Applications

Department of Energy EngineeringEnergy harvesting devices based on organic materials have attracted great attentions because the structural versatility enables the incorporation of functionality by molecular design compared to conventional inorganic solid state electronics. They also allow devices with lower costs, lightweight, large-area coverage, and mechanical flexibility. Intensive research efforts on rational molecular design and synthesis have led to remarkable progress in achieving high performance organic materials through chemical approach. One of the promising classes of organic dyes is bislactam units including diketopyrrolopyrrole (DPP), benzodithiophene (BDT), isoindigo (IIG), thienoisoindigo (TIIG), and so forth. Among them, TIIG moiety was recently developed by McCulloch et al. in 2012 through a structural modification of IIG. It exhibits a high degree of co-planarity via sulfur-oxygen interactions and improved delocalization of molecular states via a quinoidal structure along the backbone, leading to high absorption coefficients, broad light absorption and high charge carrier mobilities. Poly(vinylidene fluoride) (PVDF) is attractive for its special electrochemical and physical properties like a good surface alignment, electrochemical inertness, strong bonding strength, well-controlled porosity, superior thermal properties, and compatibility with flexible substrates. Because of its remarkable properties, it can be tailorable to many fields such as a membrane, a binder for electrode materials, piezoelectric/pyroelectric/triboelectric materials, and dielectric materials for OFETs. Grafting of functional groups to PVDF backbone can offer an effective approach for incorporating specific properties into a material while retaining desirable properties of the parent PVDF polymer. Considering above issues, my research focus was on synthesis and characterization of TIIG or PVDF-based organic materials for application in various energy harvesting devices. Firstly, three TIIG-based small molecules bearing benzene, naphthalene, and benzofuran were synthesized, characterized, and applied for organic photovoltaics (OPVs) and organic field-effect transistors (OFETs). Secondly, PVDF graft copolymers were prepared to use as a binder for Si anode in lithium ion batteries. The grafting of tert-butyl acrylate onto PVDF by ATRP was used to synthesize PVDF-g-PtBA copolymers.ope

Gating of memory encoding of time-delayed cross-frequency MEG networks revealed by graph filtration based on persistent homology

To explain gating of memory encoding, magnetoencephalography (MEG) was analyzed over multi-regional network of negative correlations between alpha band power during cue (cue-alpha) and gamma band power during item presentation (item-gamma) in Remember (R) and No-remember (NR) condition. Persistent homology with graph filtration on alpha-gamma correlation disclosed topological invariants to explain memory gating. Instruction compliance (R-hits minus NR-hits) was significantly related to negative coupling between the left superior occipital (cue-alpha) and the left dorsolateral superior frontal gyri (item-gamma) on permutation test, where the coupling was stronger in R than NR. In good memory performers (R-hits minus false alarm), the coupling was stronger in R than NR between the right posterior cingulate (cue-alpha) and the left fusiform gyri (item-gamma). Gating of memory encoding was dictated by inter-regional negative alpha-gamma coupling. Our graph filtration over MEG network revealed these inter-regional time-delayed cross-frequency connectivity serve gating of memory encoding

Formation of visual memories controlled by gamma power phase-locked to alpha oscillations

Neuronal oscillations provide a window for understanding the brain dynamics that organize the flow of information from sensory to memory areas. While it has been suggested that gamma power reflects feedforward processing and alpha oscillations feedback control, it remains unknown how these oscillations dynamically interact. Magnetoencephalography (MEG) data was acquired from healthy subjects who were cued to either remember or not remember presented pictures. Our analysis revealed that in anticipation of a picture to be remembered, alpha power decreased while the cross-frequency coupling between gamma power and alpha phase increased. A measure of directionality between alpha phase and gamma power predicted individual ability to encode memory: stronger control of alpha phase over gamma power was associated with better memory. These findings demonstrate that encoding of visual information is reflected by a state determined by the interaction between alpha and gamma activity

Genetically engineering encapsulin protein cage nanoparticle as a SCC-7 cell targeting optical nanoprobe

Background - Protein cage nanoparticles are promising nanoplatform candidates for efficient delivery systems of diagnostics and/or therapeutics because of their uniform size and structure as well as high biocompatibility and biodegradability. Encapsulin protein cage nanoparticle is used to develop a cell-specific targeting optical nanoprobe. Results - FcBPs are genetically inserted and successfully displayed on the surface of encapsulin to form FcBP-encapsulin. Selectively binding of FcBP-encapsulin to SCC-7 is visualized with fluorescent microscopy. Conclusions - Encapsulin protein cage nanoparticle is robust enough to maintain their structure at high temperature and easily acquires multifunctions on demand through the combination of genetic and chemical modifications.ope

Effect of collagen endometrial patch loaded with adipose-derived mesenchymal stem cells on endometrial regeneration in rats with a thin endometrium

BackgroundThis study aimed to investigate the effects of a collagen endometrial patch (EM patch) loaded with adipose-derived mesenchymal stem cells (ADSCs) on endometrial regeneration in a rat model with thin endometrium.Materials and methodsThin endometrium was induced in female rats and divided into treatment groups as outlined: control, group 1(G1), local injection of ADSCs into the uterus, group 2 (G2), an EM patch without ADSCs, group 3 (G3), and an EM patch loaded with ADSCs, group 4 (G4). The rats were euthanized at either two weeks or four weeks after modeling and treatment followed by histological and biochemical analyses to examine the regenerative effects on the injured endometrium.ResultsTransplantation of the ADSC-loaded EM patch significantly promoted endometrial proliferation and increased the luminal epithelial area. Two weeks after treatment, the mean number of von Villebrand factor (vWF)+ or cluster of differentiation (CD) 31+-stained blood vessels was significantly higher in G4 than in G1 and G2. The mRNA and protein expression levels of TGF-β and FGF2 were significantly upregulated in G4 compared to those in the control. G4 exhibited significantly increased LIF mRNA levels and immunoreactivity compared with the other groups at both two weeks and four weeks after treatment. Cell tracking after ADSCs treatment revealed the presence of a substantial number of ADSCs grafted in the uterine tissues of G4, whereas a low number of ADSCs that were focally clustered were present in G2.ConclusionTransplantation of EM patches loaded with ADSCs resulted in the histological and biochemical restoration of an injured endometrium. The strategic integration of EM patches and ADSCs holds significant promise as an innovative therapeutic approach for effectively treating impaired endometrial conditions

Fabrication of uniform layer-by-layer assemblies with complementary protein cage nanobuilding blocks via simple His-tag/metal recognition

A capsid-forming enzyme, lumazine synthase isolated from hyperthermophile Aquifex aeolicus (AaLS), is prepared and utilized as a template for constructing nanobuilding blocks to fabricate uniform layer-by-layer (LbL) assemblies. Two functionally complementary AaLS protein cage nanoparticles (PCNs) are generated either by genetically introducing His-tags on the surface of wild-type AaLS PCNs or by chemically attaching metal chelates (Ni-NTA moiety) to the surface of cysteine-bearing AaLS PCNs individually. The multivalent displays of His-tags (AaLS-His6 PCN) and Ni-NTA ligands (AaLS-NTA-Ni PCN) on the surface of each complementary AaLS PCN are successfully demonstrated by mass spectrometric and surface plasmon resonance analyses. By using these two complementary AaLS PCNs, uniform LbL assemblies are constructed via simple recognition between His-tags and metal chelates without the aid of additional binding mediators. This approach illustrates the potential of fabricating uniform nanostructures using protein-based hybrid functional nanobuilding blocks.close3

A TBR1-K228E Mutation Induces Tbr1 Upregulation, Altered Cortical Distribution of Interneurons, Increased Inhibitory Synaptic Transmission, and Autistic-Like Behavioral Deficits in Mice

© Copyright © 2019 Yook, Kim, Kim, Kang, Kim, Kim and Kim.Mutations in Tbr1, a high-confidence ASD (autism spectrum disorder)-risk gene encoding the transcriptional regulator TBR1, have been shown to induce diverse ASD-related molecular, synaptic, neuronal, and behavioral dysfunctions in mice. However, whether Tbr1 mutations derived from autistic individuals cause similar dysfunctions in mice remains unclear. Here we generated and characterized mice carrying the TBR1-K228E de novo mutation identified in human ASD and identified various ASD-related phenotypes. In heterozygous mice carrying this mutation (Tbr1+/K228E mice), levels of the TBR1-K228E protein, which is unable to bind target DNA, were strongly increased. RNA-Seq analysis of the Tbr1+/K228E embryonic brain indicated significant changes in the expression of genes associated with neurons, astrocytes, ribosomes, neuronal synapses, and ASD risk. The Tbr1+/K228E neocortex also displayed an abnormal distribution of parvalbumin-positive interneurons, with a lower density in superficial layers but a higher density in deep layers. These changes were associated with an increase in inhibitory synaptic transmission in layer 6 pyramidal neurons that was resistant to compensation by network activity. Behaviorally, Tbr1+/K228E mice showed decreased social interaction, increased self-grooming, and modestly increased anxiety-like behaviors. These results suggest that the human heterozygous TBR1-K228E mutation induces ASD-related transcriptomic, protein, neuronal, synaptic, and behavioral dysfunctions in mice11Nsciescopu

When river water meets seawater: Insights into primary marine aerosol production

The impact of inorganic salts and organic matter (OM) on the production of primary marine aerosols is still under debate. To constrain their impact, we investigated primary aerosols generated by a sea-spray generator chamber using surface water samples from rivers, estuaries, and seas that were collected along salinity gradients in two temperate Korean coastal systems and one Arctic coastal system. Salinity values showed an increasing trend along the river-estuary-coastal water transition, indicating the lowest amount of inorganic salts in the river but the highest amount in the sea. In river samples, the lowest number concentration of primary aerosol particles (1.01 x 10(3) cm(-3)) was observed at the highest OM content, suggesting that low salinity controls aerosol production. Moreover, the number concentration of primary aerosols increased drastically in estuarine (1.13 x 10(4) cm(-3)) and seawater (1.35 x 10(4) cm(-3)) samples as the OM content decreased. Our results indicate that inorganic salts associated with increasing salinity play a much larger role than OM in aerosol production in river-dominated coastal systems. Laboratory studies using NaCl solution supported the conclusion that inorganic salt is a critical factor in modulating the particles produced from river water and seawater. Accordingly, this study highlights that inorganic salts are a critical factor in modulating the production of primary marine aerosols. (C) 2021 The Authors. Published by Elsevier B.V

Production of Mutated Porcine Embryos Using Zinc Finger Nucleases and a Reporter-based Cell Enrichment System

To facilitate the construction of genetically-modified pigs, we produced cloned embryos derived from porcine fibroblasts transfected with a pair of engineered zinc finger nuclease (ZFN) plasmids to create targeted mutations and enriched using a reporter plasmid system. The reporter expresses RFP and eGFP simultaneously when ZFN-mediated site-specific mutations occur. Thus, double positive cells (RFP+/eGFP(+)) were selected and used for somatic cell nuclear transfer. Two types of reporter based enrichment systems were used in this study; the cloned embryos derived from cells enriched using a magnetic sorting-based system showed better developmental competence than did those derived from cells enriched by flow cytometry. Mutated sequences, such as insertions, deletions, or substitutions, together with the wild-type sequence, were found in the cloned porcine blastocysts. Therefore, genetic mutations can be achieved in cloned porcine embryos reconstructed with ZFN-treated cells that were enriched by a reporter-based system.