arteriovenous-metabolomics-to-measure-vivo-metabolite-exchange-brown

Arteriovenous Metabolomics to Measure <em>In Vivo</em> Metabolite Exchange in Brown Adipose Tissue

Brown adipose tissue (BAT) plays a crucial role in regulating metabolic homeostasis through a unique energy expenditure process known as non-shivering ...

Sungkyunkwan University (SKKU)

Herein, we report a tailored Ag mesh electrode coated with poly(3,4-ethylenedioxythiophene) (PEDOT) polymer on a flexible polyethylene terephthalate (PET) substrate. The introduction of this highly conductive polymer solves the existing problems of Ag mesh-type transparent conductive electrodes, such as high pitch, roughness, current inhomogeneity, and adhesion problems between the Ag mesh grid and PEDOT polymer or PET substrate, to result in excellent electron spreading from the discrete Ag mesh onto the entire surface without sacrificing sheet conductivity and optical transparency. Based on this hybrid anode, we demonstrate highly efficient flexible polymer solar cells (PSCs) with a high fill factor of 67.11 %, which results in a power conversion efficiency (PCE) of 6.9 % based on a poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b'] dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl) carbonyl]thieno[3,4-b]thiophenediyl}):[6,6]-phenyl-C71 -butyric acid methyl ester bulk heterojunction device. Furthermore, the PSC device with the Ag mesh electrode also exhibits a good mechanical bending stability, as indicated by a 70 % retention of the initial PCE after 500 bending cycles compared with the PSC device with a PET/indium tin oxide electrode, which retained 0 % of the initial PCE after 300 bending cycles.

Hybrid Silver Mesh Electrode for ITO-Free Flexible Polymer Solar Cells with Good Mechanical Stability.

Organic-inorganic halide perovskite materials exhibit excellent memristive properties, such as a high on/off ratio and low switching voltage. However, most studies have focused on Pb-based perovskites. Here, we report on the resistive switching and neuromorphic computing properties of Pb-free perovskite-related MA3Sb2Br9 (MA = CH3NH3). The Ag/PMMA/MA3Sb2Br9/ITO devices show forming-free characteristics due to a self-formed conducting filament induced by metallic Sb present in the as-prepared MA3Sb2Br9 layer. An MA3Sb2Br9-based memristor exhibits a reliable on/off ratio (∼102), an endurance of 300 cycles, a retention time of ∼104 s and multilevel storage characteristics. Furthermore, synaptic characteristics, such as short-term potentiation, short-term depression and long-term potentiation, are revealed along with a low energy-consumption of 117.9 fJ μm-2, which indicates that MA3Sb2Br9 is a promising material for neuromorphic computing.

Perovskite-related (CHNH)SbBr for forming-free memristor and low-energy-consuming neuromorphic computing.

Psychological distress symptoms are associated with an increased risk of psychiatric disorders and medical illness. Although psychological distress is influenced by environmental factors, such as socioeconomic status, lifetime events, or interpersonal relationships, substantial interindividual variation also exists. However, heritability and genetic determinants of distress are poorly understood.

Heritability estimates of individual psychological distress symptoms from genetic variation.

We report here the effect of interlayer spacing in 2-dimensional (2D) perovskites of [C6H5(CH2)nNH3]2PbI4 (anilinium (An) for n = 0, benzylammonium (BzA) for n = 1 and phenylethylammonium (PEA) for n = 2) on resistive switching properties. X-ray diffraction (XRD) reveals that the interlayer spacing of layered PbI2 is increased from 6.98 Å to 13.29 Å for (An)2PbI4, 14.20 Å for (BzA)2PbI4 and 15.92 Å for (PEA)2PbI4, which leads to a monolayer of organic cations with stacked benzene rings between inorganic PbI42- layers. All the samples in the device structure of Ag/PMMA (polymethyl methacrylate)/perovskite/Pt show bipolar switching behavior, where the SET voltage is near +0.2 V and the RESET voltage is less than -0.5 V. The ratio of LRS (low resistance state) to HRS (high resistance state), also called the ON/OFF ratio, is increased from 106 to 108 as interlayer spacing is increased due to the gradual increase in resistance in the HRS. Endurance is slightly improved from 1.3 × 102 for An to 2.2 × 102 for PEA, whereas substantial improvement in retention is observed from 2 × 103 to 5.5 × 103. This indicates that the enhanced 2D structure is beneficial to the kinetics of forming and rupturing the conducting filaments. The ohmic-like conduction mechanism in the LRS and the hopping mechanism in the HRS are observed for all three samples. This work finds that the resistive switching properties and conduction mechanism in the HRS depend on interlayer spacing in 2D perovskites.

Effect of interlayer spacing in layered perovskites on resistive switching memory.

We report here resistive switching memory characteristics of imidazolium lead iodide depending on the molar ratio of PbI2 to imidazolium iodide (ImI), that is, PbI2 : ImI = 1 : 0, 1 : 0.5, 1 : 1, 1 : 2, 1 : 3 and 0 : 1. X-ray diffraction confirms that the stoichiometric composition results in a hexagonal structure of (Im)PbI3, showing a one-dimensional face-sharing [PbI3-] chain. Bipolar resistive switching characteristics are observed regardless of the mixing ratio, where the forming process is required prior to SET and RESET processes at around +0.2 V and -0.2 V, respectively. The ON/OFF ratio is increased from 106 to 109 as the ImI content is increased due to the increased HRS associated with the pronounced insulating characteristics by ImI, whereas, the stoichiometric (Im)PbI3 exhibits 5 times longer endurance (103) and an order of magnitude longer retention time (104 s) as compared to other compositions. Multilevel data storage capability is confirmed by changing the compliance current. The low resistance state (LRS) and the high resistance state (HRS) are associated with Ohmic conduction and Schottky conduction, respectively. Density functional theory (DFT) calculation reveals that the defect formation energy of iodine vacancy is estimated to be low indicating that (Im)PbI3 has a sufficient concentration of iodide vacancy for filament formation. Further energy barrier calculations show that iodide migration preferentially occurs along the 1-dimensional [234] crystallographic direction rather than the interlayer [130] direction. A good performance of the (Im)PbI3-based memristor is thus related to the low defect formation energy of iodide vacancy and the preferential growth of the filament along the 1-dimensional chain.

The effect of compositional engineering of imidazolium lead iodide on the resistive switching properties.

Subjective cognitive decline (SCD) is a potential risk factor for dementia. We aimed to investigate the association between SCD and subsequent dementia in a nationwide population-based cohort in South Korea.

Subjective cognitive decline and subsequent dementia: a nationwide cohort study of 579,710 people aged 66 years in South Korea.

Genome-wide association studies (GWAS) have identified a number of genetic variants for Alzheimer's disease (AD). However, most GWAS were conducted in individuals of European ancestry, and non-European populations are still underrepresented in genetic discovery efforts. Here, we performed GWAS to identify single nucleotide polymorphisms (SNPs) associated with amyloid β (Aβ) positivity using a large sample of Korean population.

Identifying novel genetic variants for brain amyloid deposition: a genome-wide association study in the Korean population.

Lead-based halide perovskites have been proposed as potential candidates for resistive switching memristors due to the high ON/OFF ratio along with millivolt-level low operational voltage. However, lead-free perovskites with 3-dimensional structures, such as CsAgBiBr, were reported to suffer from low ON/OFF ratios. We report here that reduction of dimensionality is an effective method to improve remarkably the ON/OFF ratio in lead-free perovskites. Introduction of butylammonium (BA) into the double perovskite CsAgBiBr forms 2-dimensional BACsAgBiBr, which is confirmed by the well-developed (00l) peaks from powder X-ray diffraction. A 230 nm thick BACsAgBiBr film is sandwiched in between Ag and Pt electrodes, which demonstrates bipolar resistive switching behavior with a potential ON/OFF ratio up to 10. Reliable and reproducible SET and RESET processes occur at +0.13 V and -0.20 V, respectively. Endurance of 1000 cycles and a retention time of 2 × 10 s are measured. Multi-level storage capability is confirmed by controlling the compliance current. Schottky conduction at the high resistance state (HRS) and ohmic conduction at the low resistance state (LRS) are found to be responsible for resistive switching. The stability test at 85 °C or for 22 days under ambient conditions indicates that BACsAgBiBr is durably operable.

A layered (n-CHNH)CsAgBiBr perovskite for bipolar resistive switching memory with a high ON/OFF ratio.

Flexible and transparent artificial synapses with extremely low energy consumption have potential for use in brain-like neuromorphic electronics. However, most of the transparent materials for flexible memristive artificial synapses were reported to show picojoule-scale high energy consumption with kiloohm-scale low resistance, which limits the scalability for parallel operation. Here, we report on a flexible memristive artificial synapse based on CsCuI with energy consumption as low as 10.48 aJ (= 10.48 × 10 J) μm and resistance as high as 243 MΩ for writing pulses. Interface-type resistive switching at the Schottky junction between p-type CuCsI and Au is verified, where migration of iodide vacancies and asymmetric carrier transport owing to the effective hole mass is three times heavier than effective electron mass are found to play critical roles in controlling the conductance, leading to high resistance. There was little difference in synaptic weight updates with high linearity and 250 states before and after bending the flexible device. Moreover, the MNIST-based recognition rate of over 90% is maintained upon bending, indicative of a promising candidate for highly efficient flexible artificial synapses.

Asymmetric carrier transport in flexible interface-type memristor enables artificial synapses with sub-femtojoule energy consumption.

We investigated which factors might explain the differences between the frequencies of brain β-amyloid (Aβ) deposition in Korean and European cognitively normal individuals (CNs). We recruited 434 Korean CNs from the Samsung Medical Center (SMC) and 323 European CNs from the US Alzheimer's Disease Neuroimaging Initiative (ADNI). The Korean CNs showed lower education duration (11.8 ± 4.8 years vs. 16.8 ± 2.5 years, p < 0.001) than the European CNs. The frequency of Aβ (+) was higher in the European CNs (32.8%) than in the Korean CNs (20.0%; p < 0.001). In the SMC genome-wide association study (GWAS), 10 variants (including rs7481773 on chromosome 11, located near the brain-derived neurotrophic factor gene) exceeded the genome-wide significance level (p < 5 × 10). Especially, rs7481773 carriers showed more rapid decline in memory function than non-carriers (p = 0.048). However, this association was not observed in the ADNI GWAS. Our findings suggested that the different frequencies of Aβ (+) between CN Koreans and Europeans might be related to decreased cognitive reserve or genetic factors.

Ethnic differences in the frequency of β-amyloid deposition in cognitively normal individuals.

Subjective well-being (SWB) has been explored in European ancestral populations; however, whether the SWB genetic architecture is shared across populations remains unclear. We conducted a cross-population genome-wide association study for SWB using samples from Korean (n = 110,919) and European (n = 563,176) ancestries. Five ancestry-specific loci and twelve cross-ancestry significant genomic loci were identified. One novel locus (rs12298541 near HMGA2) associated with SWB was also identified through the European meta-analysis. Significant cross-ancestry genetic correlation for SWB between samples was observed. Polygenic risk analysis in an independent Korean cohort (n = 22,455) demonstrated transferability between populations. Significant correlations between SWB and major depressive disorder, and significant enrichment of central nervous system-related polymorphisms heritability in both ancestry populations were found. Hence, large-scale cross-ancestry genome-wide association studies can advance our understanding of SWB genetic architecture and mental health.

Shared genetic architectures of subjective well-being in East Asian and European ancestry populations.

Irritability is a heritable core mental trait associated with several psychiatric illnesses. However, the genomic basis of irritability is unclear. Therefore, this study aimed to 1) identify the genetic variants associated with irritability and investigate the associated biological pathways, genes, and tissues as well as single-nucleotide polymorphism (SNP)-based heritability; 2) explore the relationships between irritability and various traits, including psychiatric disorders; and 3) identify additional and shared genetic variants for irritability and psychiatric disorders. We conducted a genome-wide association study (GWAS) using 379,506 European samples (105,975 cases and 273,531 controls) from the UK Biobank. We utilized various post-GWAS analyses, including linkage disequilibrium score regression, the bivariate causal mixture model (MiXeR), and conditional and conjunctional false discovery rate approaches. This GWAS identified 15 independent loci associated with irritability; the total SNP heritability estimate was 4.19%. Genetic correlations with psychiatric disorders were most pronounced for major depressive disorder (MDD) and bipolar II disorder (BD II). MiXeR analysis revealed polygenic overlap with schizophrenia (SCZ), bipolar I disorder (BD I), and MDD. Conditional false discovery rate analyses identified additional loci associated with SCZ (number [n] of additional SNPs = 105), BD I (n = 54), MDD (n = 107), and irritability (n = 157). Conjunctional false discovery rate analyses identified 85, 41, and 198 shared loci between irritability and SCZ, BD I, and MDD, respectively. Multiple genetic loci were associated with irritability and three main psychiatric disorders. Given that irritability is a cross-disorder trait, these findings may help to elucidate the genomics of psychiatric disorders.

Article	Year
Hybrid Silver Mesh Electrode for ITO-Free Flexible Polymer Solar Cells with Good Mechanical Stability. ChemSusChem\| PubMed ID: 27038288	2016
Perovskite-related (CHNH)SbBr for forming-free memristor and low-energy-consuming neuromorphic computing. Nanoscale\| PubMed ID: 30892306	2019
Heritability estimates of individual psychological distress symptoms from genetic variation. Journal of affective disorders\| PubMed ID: 31003110	2019
Effect of interlayer spacing in layered perovskites on resistive switching memory. Nanoscale\| PubMed ID: 31322635	2019
The effect of compositional engineering of imidazolium lead iodide on the resistive switching properties. Nanoscale\| PubMed ID: 31334742	2019
Subjective cognitive decline and subsequent dementia: a nationwide cohort study of 579,710 people aged 66 years in South Korea. Alzheimer's research & therapy\| PubMed ID: 32375880	2020
Identifying novel genetic variants for brain amyloid deposition: a genome-wide association study in the Korean population. Alzheimer's research & therapy\| PubMed ID: 34154648	2021
A layered (n-CHNH)CsAgBiBr perovskite for bipolar resistive switching memory with a high ON/OFF ratio. Nanoscale\| PubMed ID: 34477612	2021
Asymmetric carrier transport in flexible interface-type memristor enables artificial synapses with sub-femtojoule energy consumption. Nanoscale horizons\| PubMed ID: 34668915	2021
Ethnic differences in the frequency of β-amyloid deposition in cognitively normal individuals. Neurobiology of aging\| PubMed ID: 35366586	2022
Shared genetic architectures of subjective well-being in East Asian and European ancestry populations. Nature human behaviour\| PubMed ID: 35589828	2022
Leveraging genetic overlap between irritability and psychiatric disorders to identify genetic variants of major psychiatric disorders. Experimental & molecular medicine\| PubMed ID: 37258574	2023

Soyeon Kim

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