Association between allergic diseases, generalized anxiety disorder, and depressive symptoms in South Korean adolescents: a secondary data analysis of the 2022 Korea Youth Risk Behavior Survey.

PURPOSE: This study investigated the relationship between allergic diseases, general anxiety disorder, and depressive symptoms among Korean adolescents. METHODS: A secondary analysis was conducted on the findings of the 18th Korea Youth Risk Behavior Survey (2022). The study included 51,850 adolescents and analyzed the relationships among allergic diseases, general anxiety disorder, and depressive symptoms using complex samples logistic regression analysis. RESULTS: Among the Korean adolescents, 12.7% experienced general anxiety disorder, while 28.7% experienced depressive symptoms. The prevalence of allergic diseases was 5.7% for asthma, 36.3% for allergic rhinitis, and 22.2% for atopic dermatitis. General anxiety disorder was associated with asthma and allergic rhinitis but not atopic dermatitis. Depressive symptoms were associated asthma, allergic rhinitis, and atopic dermatitis. CONCLUSION: Examining the correlation among allergic diseases, general anxiety disorder, and depressive symptoms in adolescents underscores the need for implementing suitable strategies. Moreover, when addressing general anxiety disorder and depressive symptoms in adolescents, it becomes crucial to consider the presence of allergic diseases.

Pre-crash scenarios for safety testing of autonomous vehicles: A clustering method for in-depth crash data.

Autonomous vehicles (AVs) provide an opportunity to enhance traffic safety. However, AVs market penetration is still restricted due to their safety concerns and dependability. For widespread adoption, it is crucial to thoroughly assess the safety response of AVs in various high-risk scenarios. To achieve this objective, a clustering method was used to construct typical testing scenarios based on the China In-depth Mobility Safety Study-Traffic Accident (CIMSS-TA) database. Initially, 222 car-to-powered two-wheelers (PTWs) crashes and 180 car-to-car crashes were reconstructed from CIMSS-TA database. Second, six variables were extracted and analyzed, including the motion of the two vehicles involved, relative movement, lighting condition, road condition, and visual obstruction. Third, these variables were clustered using the k-medoids algorithm, identifying five typical pre-crash scenarios for car-to-PTWs and seven for car-to-car. Additionally, we extracted the velocities and surrounding environmental information of the crash-involved parties to enrich the scenario description. The approach used in this study used in-depth case review and thus provided more insightful information for identifying and quantifying representative high-risk scenarios than prior studies that analyzed overall descriptive variables from Chinese crash databases. Furthermore, it is crucial to separately test car-to-car scenarios and car-to-PTWs scenarios due to their distinct motion characteristics, which significantly affect the resulting typical scenarios.

Evaluation of the Effectiveness of Children's Dental Care Programs: A Retrospective Study.

This study aimed to evaluate the long-term impact of children's dental care programs on children and adolescents to reduce oral health inequalities. It measured and assessed the improvement effects of children's dental care programs on the oral health of children and adolescents as part of the efforts to decrease oral health disparities in this age group. It included 406 individuals who participated in student and children's dental care program between 2013 and 2019 at screening facilities in Gwangjin-gu, Seoul. A frequency analysis was conducted for demographic characteristics, and a binary logistic regression analysis was performed to identify factors influencing the prevalence of dental caries as the dependent variable. The data were analyzed using PASW Statistics with the statistical significance level set at α = 0.05. Regarding oral health status based on the frequency of participation in children's dental care program for children and adolescents, participants with seven or more sessions had lower prevalence rates of dental caries, malocclusion, and periodontal disease than those with only one session. Second, when comparing oral health status in children's dental care program between primary and adolescent age groups, individuals under continuous oral health care showed a decrease in permanent teeth affected by dental caries, dental caries prevalence, and malocclusion prevalence (excluding primary school age). Third, a binary logistic regression analysis revealed significant influences (p < 0.05) of the developmental stage and frequency of program participation on dental caries prevalence. Children's dental care programs are essential for alleviating oral health inequalities among children and adolescents and preventing oral diseases. Furthermore, the developmental stage of children and the frequency of program participation are crucial factors in preventing oral conditions, such as dental caries.

Snowflake relocated Cu2O electrocatalyst on an Ag backbone template for the production of liquid C2+ chemicals from CO2.

In this study, we performed the CO2 reduction reaction (CO2RR) using a structural composite catalyst of cuprous oxide (Cu2O) and silver (Ag) that was simultaneously electrodeposited. While the underneath Ag electrodeposits maintained their spiky backbone structures even after the CO2RR, the Cu2O deposits were reduced to Cu(111) and relocated on the backbone template. The structural changes in Cu2O to Cu increase the active area of the Cu-Ag interface, resulting in a remarkable production rate of 125.01 µmol h-1 of liquid C2+ chemicals via the stabilization of the C-C coupling of the key intermediate species of acetaldehyde. This study provides new insights into designing a bimetallic catalyst for producing sustainable C2+ products from CO2 without any selectivity towards the production of methane.

Effects of Presenteeism on Burnout among Rehabilitation Medical Workers in Korea: Multiple Mediating Effects of Organization and Supervisor Supports.

PURPOSES: This study aimed to examine the discriminatory impacts of two major impairment factors-job presenteeism and attention presenteeism (JP and AP)-in presenteeism on burnout and to verify the multiple mediating effects of organizational and supervisory support in their causal relationship to provide theoretical and practical implications for alleviating burnout among rehabilitation medical workers (RMWs). METHODS: Participants were convenience sampled from 23 hospitals and rehabilitation medical institutions in Korea, and 494 datasets were analyzed using the R packages R-studio, Jamovi, and JASP. RESULTS: The significant effects of JP and AP on burnout were investigated; AP (0.609) had a much higher effect than JP (0.170) on burnout among RMWs. Moreover, the multiple mediating effects of organizational support and supervisory support were verified in the JP-AP relationship and burnout among RMWs. Additionally, the absolute effect on burnout was more from AP than JP, and organizational support had a far more significant effect than supervisory support in the process of affecting burnout. CONCLUSIONS: The present study contributes to the literature on burnout by examining the relationships between presenteeism and burnout and by extending the current understanding of burnout and presenteeism to RMWs. And it is practically important to understand that the effect of AP was greater than that of JP between the two key sub-factors of presenteeism affecting burnout among RMWs, and Korean RMWs are more affected by support from the organization system than by personal support from their boss. Related theoretical and practical implications are further elaborated.

Cationic charge effect of glutamine repulsion adsorbate on Li metal surfaces for highly stable lithium-sulfur batteries.

Lithium-sulfur batteries (LSBs) are superior next-generation batteries compared to commercial lithium-ion batteries (LiBs) because of their gravimetric energy densities, which provide longer battery life in a lighter package. However, the biggest hurdle for commercializing LSBs is their poor long-term cycling performance, which stems from polysulfide shuttling. To address this issue, we propose a novel approach: the use of glutamine, an amino acid, as an electrolyte additive to increase the cycling stability. Due to its molecular structure containing amines, the formation of Li dendrites was obstructed by homogenizing the Li-ion flux to shield the exceedingly active Li surfaces with glutamine, thereby reducing the overvoltage during Li plating and stripping. Additionally, the redox reactions of lithium polysulfides were enhanced, which helped to alleviate the shuttling of lithium polysulfides. Therefore, the addition of glutamine improved the stability and reduced the cell degradation rate by approximately 0.066% during high C-rate long-term cycling tests.

Dynamic short-term crash analysis and prediction at toll plazas for proactive safety management.

Toll plazas are commonly recognized as bottlenecks on toll roads, where vehicles are prone to crashes. However, there has been a lack of research analyzing and predicting dynamic short-term crash risk specifically at toll plazas. This study utilizes traffic, geometric, and weather data to analyze and predict dynamic short-term collision occurrence probability at mainline toll plazas. A random-effects logit regression model is employed to identify crash precursors and assess their impacts on the probability of crash occurrence at toll plazas. Meanwhile, a Long Short-Term Memory Convolutional Neural Network (LSTM-CNN) network is applied for crash prediction. The results of random-effects logit regression model indicate that the flow standard deviation of downstream, upstream occupancy, speed difference and occupancy difference between upstream and downstream positively influence the probability of crash occurrence. Conversely, an increase in the proportion of ETC lanes negatively impacts the probability of crash occurrence. Additionally, there appears a higher likelihood of crashes occurring during summer at toll plaza area. Furthermore, to address the issue of data imbalance, Synthetic Minority Oversampling Techniques (SMOTE) and class weight methods were employed. Stacked Sparse AutoEncoder-Long Short-Term Memory (SSAE-LSTM) and CatBoost were developed and their performance was compared with the proposed model. The results demonstrated that the LSTM-CNN model outperformed the other models in terms of the Area Under the Curve (AUC) values and the true positive rate. The findings of this study can assist engineers in selecting suitable traffic control strategies to improve traffic safety in toll plaza areas. Moreover, the developed collision prediction model can be incorporated into a real-time safety management system to proactively prevent traffic crash.

The use of mouthguards and related factors among basketball players in Indonesia.

BACKGROUND: Basketball is a sport with a higher injury rate. Regardless, few basketball players use mouthguards, which predisposes them to injuries. The use of mouthguards (UoM) could be related to several factors. This study aims to identify factors associated with UoM and to construct a model from the factors among basketball players in Indonesia. METHODS: Through convenience sampling, a total of 286 among basketball players in Indonesia was included in this cross-sectional study. These participants filled out online a modified questionnaires regarding demographic and several factors related to UoM. The data was analyzed using chi-square test, independent-sample t-test, binary logistic regression, and structural equation modeling (SEM). RESULTS: There were 286 players. 127 of them were males and 159 were females. Of them, 86 (30.1%) used mouthguards. Age, duration (in year), and weekly practicing basketball (in hour) were all significantly different between mouthguards users and non-users with (p = 0.005, p = 0.036 and p = 0.035), respectively. The UoM was significantly associated with level of awareness, injury experience, social support, and oral health professional (OHP) support with (p = 0.002, p < 0.001, p < 0.001 and p < 0.001), respectively. This result was also supported by a variety of variables' ORs, which range from 1.28 to 5.97. The coefficient of determination (R2) was 0.27. CONCLUSIONS: The UoM among basketball players in Indonesia was related to several factors, including the level of knowledge, level of awareness, duration of basketball career, injury experiences, social support, and oral health professionals' support which was constructed to propose a model. The model could explain 27% of the relationship between variables and UoM among Indonesian basketball players. This model will be useful for more comprehensive initiatives to promote oral health. It might be applicable for other countries as well as other sports communities / physical activities.

Enhancement of the therapeutic efficacy of the MAP regimen using thiamine pyrophosphate-decorated albumin nanoclusters in osteosarcoma treatment.

Recent studies on osteosarcoma regimens have mainly focused on modifying the combination of antineoplastic agents rather than enhancing the therapeutic efficacy of each component. Here, an albumin nanocluster (NC)-assisted methotrexate (MTX), doxorubicin (DOX), and cisplatin (MAP) regimen with improved antitumor efficacy is presented. Human serum albumin (HSA) is decorated with thiamine pyrophosphate (TPP) to increase the affinity to the bone tumor microenvironment (TME). MTX or DOX (hydrophobic MAP components) is adsorbed to HSA-TPP via hydrophobic interactions. MTX- or DOX-adsorbed HSA-TPP NCs exhibit 20.8- and 1.64-fold higher binding affinity to hydroxyapatite, respectively, than corresponding HSA NCs, suggesting improved targeting ability to the bone TME via TPP decoration. A modified MAP regimen consisting of MTX- or DOX-adsorbed HSA-TPP NCs and free cisplatin displays a higher synergistic anticancer effect in HOS/MNNG human osteosarcoma cells than conventional MAP. TPP-decorated NCs show 1.53-fold higher tumor accumulation than unmodified NCs in an orthotopic osteosarcoma mouse model, indicating increased bone tumor distribution. As a result, the modified regimen more significantly suppresses tumor growth in vivo than solution-based conventional MAP, suggesting that HSA-TPP NC-assisted MAP may be a promising strategy for osteosarcoma treatment.

Pixel Diffuser: Practical Interactive Medical Image Segmentation without Ground Truth.

Medical image segmentation is essential for doctors to diagnose diseases and manage patient status. While deep learning has demonstrated potential in addressing segmentation challenges within the medical domain, obtaining a substantial amount of data with accurate ground truth for training high-performance segmentation models is both time-consuming and demands careful attention. While interactive segmentation methods can reduce the costs of acquiring segmentation labels for training supervised models, they often still necessitate considerable amounts of ground truth data. Moreover, achieving precise segmentation during the refinement phase results in increased interactions. In this work, we propose an interactive medical segmentation method called PixelDiffuser that requires no medical segmentation ground truth data and only a few clicks to obtain high-quality segmentation using a VGG19-based autoencoder. As the name suggests, PixelDiffuser starts with a small area upon the initial click and gradually detects the target segmentation region. Specifically, we segment the image by creating a distortion in the image and repeating it during the process of encoding and decoding the image through an autoencoder. Consequently, PixelDiffuser enables the user to click a part of the organ they wish to segment, allowing the segmented region to expand to nearby areas with pixel values similar to the chosen organ. To evaluate the performance of PixelDiffuser, we employed the dice score, based on the number of clicks, to compare the ground truth image with the inferred segment. For validation of our method's performance, we leveraged the BTCV dataset, containing CT images of various organs, and the CHAOS dataset, which encompasses both CT and MRI images of the liver, kidneys and spleen. Our proposed model is an efficient and effective tool for medical image segmentation, achieving competitive performance compared to previous work in less than five clicks and with very low memory consumption without additional training.

Local Myeloid-Derived Suppressor Cells Impair Progression of Experimental Autoimmune Uveitis by Alleviating Oxidative Stress and Inflammation.

Purpose: To evaluate the immune regulatory effect of human cord blood myeloid-derived suppressor cells (MDSCs) in experimental autoimmune uveitis (EAU) models. Methods: MDSCs (1 × 106) or PBS were injected into established C57BL/6 EAU mice via the subconjunctival route on days 0 and 7. The severity of intraocular inflammation was evaluated for up to 3 weeks. Tissue injury and inflammation were analyzed using immunolabelled staining, real-time PCR, and ELISA. In addition, immune cells in draining lymph nodes (LNs) were quantified using flow cytometry. Results: After 21 days, the clinical scores and histopathological grades of EAU were lower in the MDSCs group compared with the PBS group. Local administration of MDSCs suppressed the oxidative stress and the expression of TNF-α and IL-1ß in the retinal tissues. In addition, it inhibited the activation of pathogenic T helper 1 (Th1) and Th17 cells in draining LNs. MDSCs increased the frequency of CD25+ Foxp3+ regulatory T cells and the mRNA expression of IL-10, as an immune modulator. Conclusions: MDSCs suppressed inflammation and oxidative stress in the retina and inhibited pathogenic T cells in the LNs in EAU. Therefore, ocular administration of MDSCs has therapeutic potential for uveitis.

Oral Probiotics, Streptococcus salivarius K12 and M18, Suppress the Release of Volatile Sulfur Compounds and a Virulent Protease from Oral Bacteria: An In-Vitro Study.

PURPOSE: To evaluate the inhibitory effects of Streptococcus salivarius K12 and M18 strains on the growth of six oral pathogens as well as their release of volatile sulfur compounds (VSCs), and whether these probiotics can inhibit the expression of arginine-specific gingipain A (RgpA), a protease secreted by Porphyromonas gingivalis. MATERIALS AND METHODS: After six halitogenic oral pathogens (P. gingivalis, Treponema denticola, Tannerella forsythia, Fusobacterium nucleatum, Parvimonas micra, and Eikenella corrodens) were cultured with or without S. salivarius K12 and M18, the concentration of two VSCs was measured. Moreover, the antimicrobial activity of S. salivarius K12 and M18 against these pathogens and the suppressive effect on RgpA release by P. gingivalis were assessed. RESULTS: In the co-culture of S. salivarius K12 or M18 with oral pathogenic bacteria, the growth of all six oral pathogens was significantly inhibited (p < 0.01). Additionally, S. salivarius K12 and M18 had an inhibitory effect on the production of the halitogenic substances H2S and CH3SH (p < 0.01) as well as the expression of P. gingivalis RgpA. Finally, we demonstrated that the addition of only culture supernatants of the two strains K12/M18 to oral pathogen cultures was sufficient to mimic the effects of K12/M18 co-cultures upon VSCs production and protease expression. CONCLUSIONS: S. salivarius K12 and M18 inhibited VSC release by all six of the major oral pathogens that were assayed and reduced the expression of RgpA.

Sialic acid-decorated liposomes enhance the anti-cancer efficacy of docetaxel in tumor-associated macrophages.

Tumor-associated macrophages (TAMs) in the tumor microenvironment potentially enhance tumor growth and invasion through various mechanisms and are thus an essential factor in tumor immunity. The highly expressed siglec-1 receptors on the surfaces of TAMs are potential targets for cancer drug delivery systems. Sialic acid (SA) is a specific ligand for siglec-1. In this study, the sialic acid-polyethylene glycol conjugate (DSPE-PEG2000-SA) was synthesized to modify the surface of liposomes and target TAMs by interacting with the siglec-1 receptor. Three docetaxel (DTX)-loaded liposomes, conventional (DTX-CL), DSPE-PEG2000-coated (DTX-PL), and DSPE-PEG2000-SA-coated (DTX-SAPL) liposomes, were prepared, with a particle size of <100 nm, uniform polydispersity index (PDI) values, negative zeta potential, and % encapsulation efficiency (EE) exceeding 95 %. Liposomes showed high stability after 3 months of storage at 4 °C without significant changes in particle size, PDI, zeta potential, or % EE. DTX was released from liposomes according to the Weibull model, and DTX-SAPL exhibited more rapid drug release than other liposomes. In vitro studies demonstrated that DTX-SAPL liposome exhibited a higher uptake and cytotoxicity on RAW 264.7 cells (TAM model) and lower toxicity on NIH3T3 cells (normal cell model) than other formulations. The high cell uptake ability was demonstrated by the role of the SA-SA receptor. Biodistribution studies indicated a high tumor accumulation of surface-modified liposomal formulations, particularly SA-modified liposomes, showing high signal accumulation at the tumor periphery, where TAMs were highly concentrated. Ex vivo imaging showed a significantly higher accumulation of SA-modified liposomes in the tumor, kidney, and heart than conventional liposomes. In the anti-cancer efficacy study, DTX-SAPL liposomes showed effective inhibition of tumor growth and relatively low systemic toxicity, as evidenced by the tumor volume, tumor weight, body weight values, and histopathological analysis. Therefore, DSPE-PEG2000-SA-coated liposomes could be promising carriers for DTX delivery targeting TAMs in cancer therapy.

Distribution of Bioelectrical Impedance Vector Analysis and Phase Angle in Korean Elderly and Sarcopenia.

PURPOSE: This study aimed to verify whether bioelectrical impedance vector analysis (BIVA) can support the clinical evaluation of sarcopenia in elderly individuals and evaluate the relationships between phase angle (PhA), physical performance, and muscle mass. METHODS: The sample comprised 134 free-living elderly individuals of both sexes aged 69-91 years. Anthropometric parameters, grip strength, dual-energy X-ray absorptiometry findings, bioimpedance analysis results, and physical performance were also measured. The impedance vector distributions were evaluated in elderly individuals using BIVA. RESULTS: BIVA revealed significant differences between the sarcopenia and non-sarcopenia groups (both sexes). The sarcopenia group had a significantly lower PhA than the non-sarcopenia group in both sexes (p < 0.05). PhA was significantly correlated with age, appendicular skeletal muscle (ASM), handgrip strength (HGS), and muscle quality in both sexes and significantly correlated with ASM/Height2 and physical performance in males. CONCLUSION: BIVA can be used as a field assessment method in elderly Koreans with sarcopenia. PhA is a good indicator of muscle strength, muscle quality, and physical performance in males. These methods can help diagnose sarcopenia in elderly individuals with reduced mobility.

Sustained delivery of triamcinolone acetonide from a thermosensitive microemulsion gel system for the treatment of sensorineural hearing loss.

Intratympanic administration for the delivery of steroids has been extensively studied but limited because of low permeability of the drug through the row window membrane. Here, to effectively deliver poorly soluble triamcinolone acetonide (TA), microemulsions (ME) were prepared from Capmul MCM (oil), Cremophor RH40 (surfactant), and tetraglycol (cosurfactant) based on solubility studies, emulsifying ability test, and pseudoternary phase diagrams. Microemulsion gel (MEG) was prepared by mixing TA-ME with a poloxamer hydrogel base. The physicochemical properties of ME and MEG formulations were characterized, and the toxicity and oto-protective effectiveness were evaluated in vitro and in vivo. The ME-3 formulation showed a small droplet size (16.5 ± 0.2 nm), narrow PDI (0.067 ± 0.041), and enhanced TA solubility (2619.7 ± 57.6 µg/g). The optimized MEG demonstrated temperature-dependent gelation with a gelation time of 208 ± 10 sec at 37 °C. Slow degradation of the gel matrix sustained release of TA from MEG compared to the ME formulation. Both TA-ME and TA-MEG were found to be nontoxic to NIH3T3 cells at the test concentrations (0 to 5 µg/mL), and biocompatible after intratympanic administration to mice. The incorporation of ME into thermosensitive hydrogels prolonged retention of TA at the site of administration until 6 days. As a consequence, the enhanced drug absorption into the cochlea in TA-MEG group (approximately 2 times higher than other groups) protected hair cells, spiral ganglion neurons, and stria vascular cells from cisplatin-induced damage. Therefore, this injectable TA-loaded MEG is an effective and safe vehicle for the sustained delivery of triamcinolone acetonide into the inner ear.

Identifying typical pre-crash scenarios based on in-depth crash data with deep embedded clustering for autonomous vehicle safety testing.

Choosing appropriate scenarios is critical for autonomous vehicles (AVs) safety testing. Real-world crash scenarios can be used as critical scenarios to test the safety performance of AVs. As one of the dominant types of traffic crashes, the car to powered-two-wheelers (PTWs) crash results in a higher possibility of fatality than ordinary car-to-car crashes. Generally, typical testing scenarios are chosen according to the subjective understanding of the safety experts with limited static features of crashes (e.g., geometric features, weather). This study introduced a novel method to identify typical car-to-PTWs crash scenarios based on real-world crashes with dynamic pre-crash features investigated from the China In-depth Mobility Safety Study-Traffic Accident (CIMSS-TA) database. First, we present crash data collection and construction methods of the CIMSS-TA database to construct testing scenarios. Second, the stacked autoencoder methods are used to learn and obtain embedded features from the high-dimensional data. Third, the extracted features are clustered using k-means clustering algorithm, and then the clustering results are interpreted. Six typical car-to-PTWs scenarios are obtained with the proposed processes. This study introduces a typical high-risk scenario construction method based on deep embedded clustering. Unlike existing researches, the proposed method eliminates the negative impacts of manually selecting clustering variables and provides a more detailed scenario description. As a result, the typical scenarios obtained from AV testing are more robust.

Effectiveness of the COVID-19 vaccine in the Honam region of the Republic of Korea.

BACKGROUND: In 2021, the effectiveness of the COVID-19 vaccine was analyzed among people living in the Honam region (Gwangju, Jeollanam-do, Jeollabuk-do, and Jeju) of the Republic of Korea. And we investigated changes in the dominant virus strain. METHODS: This study used the data provided by the Korean Ministry of the Interior and Safety for individuals ≥12 years old in the Honam region, and the Integrated Disease and Health Management System of the Korea Centers for Disease Control and Prevention for COVID-19-vaccinated individuals as of December 31, 2021. Statistical analyzes were performed using IBM SPSS ver. 23.0. The occurrence of confirmed cases by vaccination status, the relative risk, and vaccine effectiveness by vaccine type were calculated. RESULTS: In 2021, the COVID-19 vaccination rate in Honam was 88.6%. The overall vaccine effectiveness (after 2 and 3 doses) was 98.7% (p<0.001). and the breakthrough infection rate was 0.16%. From week 21 to week 27 of 2021 (June 27 to July 3), the genome sequencing results were mostly alpha variants. The Delta variant emerged as the dominant variant after 27 weeks and the Omicron variant was found at 50 weeks (December 5-11). CONCLUSION: Vaccine effectiveness changed with the outbreak of new variants of the virus as well as over time as antibody levels decreased. that the prevention effectiveness of vaccination in Honam was >98%, and the effect among persons who received 2 doses was >90% regardless of the vaccine type. Although vaccine effectiveness decreased because of reduced antibody levels over time (as observed in breakthrough infections), receiving a booster dose restored the neutralizing antibody levels.

Changes in traffic crash patterns: Before and after the outbreak of COVID-19 in Florida.

In the twentieth year of the twenty-first century, humanity is facing an unprecedented global crisis owing to the COVID-19 pandemic. It has brought about drastic changes in the way we live and work, as well as the way we move from one place to another, namely transportation. Previous studies have preliminarily found that mobility, travel behavior, and road traffic safety status experienced great changes after the outbreak of the COVID-19. The objective of this study is to explore how crash patterns have changed, as well as the contributing factors of such changes and the heterogeneity between counties in Florida. Thus, data of COVID-19 cases, crash, socioeconomic factors, and traffic volume of 2019 and 2020 are collected. Preliminary analyses show a considerable reduction from March to June. Substantial changes are shown in the proportions of crashes by time of occurrence and injury severity. Two types of statistical models are developed to identify factors of (1) changes in the percentages of crashes by type and (2) the numbers of crashes by type. The developed models reveal various demographic, socioeconomic, and travel factors. After controlling other factors, the total numbers of crashes are 14% lower after the outbreak. The most significant reductions are observed in peak-hour (22%), while no significant change is found in fatal crashes. The results show that the number of crashes has significantly decreased even after controlling the traffic volume, but some crash types (e.g., fatal) did not show a significant reduction. The findings are expected to provide some insights into better transportation planning and management to ensure traffic safety in a possible future epidemic.

Surface Engineering of Metal and Semiconductor Nanocrystal Assemblies and Their Optical and Electronic Devices.

ConspectusColloidal nanocrystals (NCs) are composed of inorganic cores and organic or inorganic ligand shells and serve as building blocks of NC assemblies. Metal and semiconductor NCs are well known for the size-dependent physical properties of their cores. The large NC surface-to-volume ratio and the space between NCs in assemblies places significant importance on the composition of the NC surface and ligand shell. Nonaqueous colloidal NC syntheses use relatively long organic ligands to control NC size and uniformity during growth and to prepare stable NC dispersions. However, these ligands create large interparticle distances that dilute the metal and semiconductor NC properties of their assemblies. In this Account, we describe postsynthesis chemical treatments to engineer the NC surface and design the optical and electronic properties of NC assemblies. In metal NC assemblies, compact ligand exchange reduces the interparticle distance and drives an insulator-to-metal transition tuning the dc resistivity over a 1010 range and the real part of the optical dielectric function from positive to negative across the visible-to-IR region. Juxtaposing NC and bulk metal thin films in bilayers allows the differential chemical and thermal addressability of the NC surface to be exploited in device fabrication. Ligand exchange and thermal annealing densifies the NC layer, creating interfacial misfit strain that triggers folding of the bilayers and is used to fabricate, with only one lithography step, large-area 3D chiral metamaterials. In semiconductor NC assemblies, chemical treatments such as ligand exchange, doping, and cation exchange control the interparticle distance and composition to add impurities, tailor stoichiometry, or make entirely new compounds. These treatments are employed in longer studied II-VI and IV-VI materials and are being developed as interest in III-V and I-III-VI2 NC materials grows. NC surface engineering is used to design NC assemblies with tailored carrier energy, type, concentration, mobility, and lifetime. Compact ligand exchange increases the coupling between NCs but can introduce intragap states that scatter and reduce the lifetime of carriers. Hybrid ligand exchange with two different chemistries can enhance the mobility-lifetime product. Doping increases carrier concentration, shifts the Fermi energy, and increases carrier mobility, creating n- and p-type building blocks for optoelectronic and electronic devices and circuits. Surface engineering of semiconductor NC assemblies is also important to modify device interfaces to allow the stacking and patterning of NC layers and to realize excellent device performance. It is used to construct NC-integrated circuits, exploiting the library of metal, semiconductor, and insulator NCs, to achieve all-NC, solution-fabricated transistors.

Chemical Glycosylation with p-Methoxyphenyl (PMP) Glycosides via Oxidative Activation.

A novel persulfate-mediated oxidative glycosylation system using p-methoxyphenyl (PMP) glycosides as bench-stable glycosyl donors is developed. This study shows that both K2S2O8 as an oxidant and Hf(OTf)4 as a Lewis acid catalyst play important roles in the oxidative activation of the PMP group into a potential leaving group. This convenient glycosylation protocol proceeds under mild conditions and delivers a wide range of biologically and synthetically valuable glycoconjugates, including glycosyl fluorides.