Synthesis of Tethering Group on Borylazadipyrromethene Dyes to Apply to Photogalvanic Dye-sensitized Solar Cells

This is my thesis research on the preparation of borylazadipyrromethene (azaBODIPY) dyes bearing an anchoring group, such as a carboxylic acid group, at the β-pyrrolic position of the azadipyrromethene scaffold. Carboxylate groups form covalent bonds to oxide semiconductors such as TiO2 (n-type) or Cu2O (p-type) in dye-sensitized solar cells (DSCs) or photogalvanic dye-sensitized solar cells (P-DSCs). Oxide-binding azaBODIPY dyes can be used to investigate the rate and mechanism of electron injection from the dyes to the semiconductors. Two different types of azaBODIPY (difluoroboryl and dialkynylboryl) were prepared by following previously developed methods. To convert difluoroborylazaBODIPY to the final dyes having a carboxylic acid in the β-pyrrolic position, several distinct synthetic routes were designed, adopting various reactions, such as halogenation, Sonogashira coupling, Knoevenagel condensation, Grignard reagents, Vilsmeir-Haack, and Steglich esterification. Some of these reactions were successful, but the overall synthesis to the targeted final molecule couldn’t be accomplished. Even though further studies on the synthesis of oxide-binding azaBODIPYs are needed, at least my thesis research suggests what reactions can be implemented to complete this synthesis in the future. Proton NMR (nuclear magnetic resonance) and carbon NMR were commonly used to confirm the synthesized compounds, and sometimes crystallographic information was obtained by XRD (X-ray diffraction) whenever crystals of sufficient size and quality were grown. NMR spectra, interpreted by SpinWorks 3 software, and crystal structures will be introduced in each chapter

Analysis of Intrinsic Factors Leading to Aggressive Driving Behavior to Derive Safety Policy Implications for Bus Drivers

Significant efforts to develop effective safety policies are essential to prevent bus traffic accidents because city buses accommodate many passengers. An in-depth analysis of causal factors that can be the intrinsic cause of aggressive driving is a first step toward preparing for effective bus safety policies. This study aims to explore traffic safety policy implications and analyze development priorities based on the aforementioned factors including the working environment, health characteristics, human characteristics, living environment, and bus route characteristics. Bus driver survey data obtained by self-reported survey instruments were used to discover factors that affect aggressive driving behavior captured by an in-vehicle data recorder. A binary logistic regression model was established using driver characteristics as independent variables and the level of aggressive driving behavior as the dependent variables. From the model, a total of nine independent variables that have a statistically significant effect on aggressive driving behavior by bus drivers were found. This study then suggested seven bus safety policy implications based on the identified influencing factors. The results of the prioritizing the policy implications show that detailed regulations related to break times for city bus drivers, improvement of company break rooms, and management measures for bus driver mental health and psychological conditions were the top three. The findings of this study would be valuable for the development of effective traffic safety policies that reflect the characteristics of the city bus industry

A Systematic Removal of Minimum Implant Area Violations under Timing Constraint

Fixing minimum implant area (MIA) violations in the post-route layout is an essential and inevitable task for the high-performance designs employing multiple threshold voltages. Unlike the conventional approaches, which have tried to locally move cells or reassign V-t (threshold voltage) of some cells in a way to resolve the MIA violations with little or no consideration of timing constraint, our proposed approach fully and systematically controls the timing budget during the removal of MIA violations. Precisely, our solution consists of three sequential steps: (1) performing critical path aware cell selection for V-t reassignment to fix the intra-row MIA violations while considering timing constraint and minimal power increments; (2) performing a theoretically optimal V-t reassignment to fix the inter-row MIA violations while satisfying both of the intra-row MIA and timing constraints; (3) refining V-t reassignment to further reduce the power consumption while meeting intra- and inter-row MIA constraints as well as timing constraints. Experiments through benchmark circuits show that our proposed approach is able to completely resolve MIA violations while ensuring no timing violation and achieving much less power increments over that by the conventional approaches.N

Minimum Implant Area-Aware Threshold Voltage Refinement in Pre-Placement

Using multiple threshold voltages (Multi-V-t) is widely adopted due to its effectiveness to optimize the balance between power and timing In the meantime, as the technology node shrinks, the minimum implant area (MIA) constraint has become an emerging challenge in multi-V-t circuit designs. In this paper, we propose an MIA-aware V-t refinement algorithm to be performed in a way to reduce the number of occurrences of MIA violations. Our key idea is to update the V-t of small size cells that are likely to incur MIA violations in advance before cell placement, thereby relieving the burden of fixing MIA violations during the placement stage that performs the operations of moving/swapping cells or trading circuit timing with V-t change. Through experiments with benchmark circuits, it is shown that our proposed method is able to reduce the number of MIA violations by up to 16% with no timing penalty.N

Supplemental Material - Persistent Exposure to Work Family Conflict and Depressive Symptoms Among Korean Working Women: An Exploration of Temporal Patterns and Age Heterogeneity

Supplemental Material for Persistent Exposure to Work Family Conflict and Depressive Symptoms Among Korean Working Women: An Exploration of Temporal Patterns and Age Heterogeneity by Gum-Ryeong Park, Eunsol Song, and Jinho Kim in Journal of Family Issues.</p

Conjugated Polymer/Semiconducting Carbon Nanotubes Composite Semiconductor Ink for Stretchable Active Matrix Display

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Seroprevalence of Varicella-Zoster Virus and Measles among Healthcare Workers in a Tertiary Medical Center in Korea

Measles and varicella still occur in the general population despite the widespread vaccination against them, and healthcare workers (HCWs) are still at risk of exposure to these diseases. Here, we evaluated the seroprevalence of measles and varicella-zoster virus (VZV) in HCWs and the trend of seroprevalence according to age, birth year, and occupational group. The serostatuses of measles and VZV of HCWs during new employee medical examinations between October 2015 and October 2021 were included. Thereafter, the trends of seroprevalence according to age, birth year, and occupational groups were evaluated. Overall, 2070 and 1827 HCWs were evaluated for VZV and measles serostatus, respectively. The seroprevalences of VZV and measles were 91% (1884/2070) and 70% (1284/1827), respectively. Younger HCWs had a significantly lower seroprevalence of measles (p = 0.02, age) and VZV (p = 0.003, birth year and p p < 0.001 in both). In conclusion, the seroprevalence of measles and VZV significantly decreased in younger HCWs. Additionally, monitoring the serostatus of measles and VZV and the immunization of susceptible HCWs are required to prepare and control infectious diseases in healthcare facilities

Alendronate/cRGD-Decorated Ultrafine Hyaluronate Dot Targeting Bone Metastasis

In this study, we report the hyaluronate dot (dHA) with multiligand targeting ability and a photosensitizing antitumor model drug for treating metastatic bone tumors. Here, the dHA was chemically conjugated with alendronate (ALN, as a specific ligand to bone), cyclic arginine-glycine-aspartic acid (cRGD, as a specific ligand to tumor integrin &alpha;v&beta;3), and photosensitizing chlorin e6 (Ce6, for photodynamic tumor therapy), denoted as (ALN/cRGD)@dHA-Ce6. These dots thus prepared (&asymp;10 nm in diameter) enabled extensive cellular interactions such as hyaluronate (HA)-mediated CD44 receptor binding, ALN-mediated bone targeting, and cRGD-mediated tumor integrin &alpha;v&beta;3 binding, thus improving their tumor targeting efficiency, especially for metastasized MDA-MB-231 tumors. As a result, these dots improved the tumor targeting efficiency and tumor cell permeability in a metastatic in vivo tumor model. Indeed, we demonstrated that (ALN/cRGD)@dHA-Ce6 considerably increased photodynamic tumor ablation, the extent of which is superior to that of the tumor ablation of dot systems with single or double ligands. These results indicate that dHA with multiligand can provide an effective treatment strategy for metastatic bone tumors

Enzyme Mediated Increase in Methanol Production from Photoelectrochemical Cells and CO₂

While success has been shown in utilizing photocatalytic systems to reduce CO₂ in water, most of these studies have yielded formic acid as the major product with trace amounts of formaldehyde or methanol. One reason for this is the strong equilibrium of formaldehyde toward the hydrate methanediol. To increase methanol yields from CO₂, we show here the combined use of the biological catalyst alcohol dehydrogenase (ADH) from <i>Saccharomyces cerevisiae</i> with CO₂ reduction products obtained from photoelectrochemical cells (PEC). We first show that ADH can reduce very low micromolar amounts of formaldehyde in solution. Upon adding ADH to the PEC products, a rapid three- to four-fold gain in methanol production was observed, which we also attribute to the lack of back reaction by the enzyme. Lastly, because formaldehyde dehydrogenase (FalDH) showed very low reactivity with formate, the addition of FalDH and ADH to the PEC products demonstrated no difference in methanol yields as compared to ADH alone