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In many cases of traumatic brain injury (TBI), conspicuous abnormalities, such as scalp wounds and intracranial hemorrhages, abate over time. However, many unnoticeable symptoms, including cognitive, emotional, and behavioral dysfunction, often last from several weeks to years after trauma, even for mild injuries. Moreover, the cause of such persistence of symptoms has not been examined extensively. Recent studies have implicated the dysregulation of the molecular system in the injured brain, necessitating an in-depth analysis of the proteome and signaling pathways that mediate the consequences of TBI. Thus, in this study, the brain proteomes of two TBI models were examined by quantitative proteomics during the recovery period to determine the molecular mechanisms of TBI. Our results show that the proteomes in both TBI models undergo distinct changes. A bioinformatics analysis demonstrated robust activation and inhibition of signaling pathways and core proteins that mediate biological processes after brain injury. These findings can help determine the molecular mechanisms that underlie the persistent effects of TBI and identify novel targets for drug interventions.
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Lesões Encefálicas Traumáticas , Lesões Encefálicas , Animais , Roedores/metabolismo , Proteômica/métodos , Proteoma/genética , Proteoma/metabolismo , Lesões Encefálicas Traumáticas/metabolismo , Lesões Encefálicas/metabolismoRESUMO
TyG (triglyceride and glucose) index using triglyceride and fasting blood glucose is recommended as a useful marker for insulin resistance. To clarify whether the TyG index is a marker for predicting metabolic syndrome (MetS) and to investigate the importance of single-nucleotide polymorphisms (SNPs) in MetS diagnosis. From 2001 to 2014, a longitudinal prospective cohort study of 3580 adults aged 40-70 years was conducted. The area under the receiver operating characteristic curves (AUROC) and Youden index (YI) was calculated to assess the diagnostic value. During the 14-year follow-up, 1270 subjects developed MetS. Five SNPs in four genes (BUD13 rs10790162, ZPR1 rs2075290, APOA5 rs2266788, APOA5 rs2075291, and MKL1 rs4507196) significantly correlated with susceptibility to MetS (p < 0.00005). The areas under the curve of TyG index and HOMA-IR were 0.854 (95% confidence interval [CI], 0.841-0.867) and 0.702 (95% CI, 0.684-0.721), respectively. Despite no statistical significance, AUROC and YI were increased when MetS was diagnosed using TyG index and the five SNPs. TyG index might be useful for identifying individuals at high risk of developing MetS. The combination of TyG index and SNPs showed better diagnostic accuracy than TyG index alone, indicating the potential value of novel SNPs for MetS diagnosis.
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Resistência à Insulina , Síndrome Metabólica , Adulto , Humanos , Biomarcadores , Glicemia , Resistência à Insulina/genética , Síndrome Metabólica/diagnóstico , Síndrome Metabólica/genética , Polimorfismo de Nucleotídeo Único , Estudos Prospectivos , Triglicerídeos , Pessoa de Meia-Idade , IdosoRESUMO
For in-vehicle network communication, the controller area network (CAN) broadcasts to all connected nodes without address validation. Therefore, it is highly vulnerable to all sorts of attack scenarios. This research proposes a novel intrusion detection system (IDS) for CAN to identify in-vehicle network anomalies. The statistical characteristics of attacks provide valuable information about the inherent intrusion patterns and behaviors. We employed two real-world attack scenarios from publicly available datasets to record a real-time response against intrusions with increased precision for in-vehicle network environments. Our proposed IDS can exploit malicious patterns by calculating thresholds and using the statistical properties of attacks, making attack detection more efficient. The optimized threshold value is calculated using brute-force optimization for various window sizes to minimize the total error. The reference values of normality require a few legitimate data frames for effective intrusion detection. The experimental findings validate that our suggested method can efficiently detect fuzzy, merge, and denial-of-service (DoS) attacks with low false-positive rates. It is also demonstrated that the total error decreases with an increasing attack rate for varying window sizes. The results indicate that our proposed IDS minimizes the misclassification rate and is hence better suited for in-vehicle networks.
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Fenugreek is a widely used herbal medicine as a complementary therapy for diabetes mellitus. Lots of clinical trials have proved its beneficial effect on glycemic control parameters and lipid profiles. Thus, we conducted a systematic review and meta-analysis to evaluate the effectiveness and safety of fenugreek as a treatment for type 2 diabetes mellitus. We searched PubMed, Embase, Cochrane, China Knowledge Resource Integrated Database (CNKI), Korean studies Information Service System (KISS), Research Information Sharing Service (RISS), and ScienceON to select RCTs which used fenugreek targeting hyperglycemia with a control group. We used either a random effect model or a fixed model in a meta-analysis of Fasting blood glucose (FBG), 2 h plasma glucose during a 75 g oral glucose tolerance test (OGTT) (2-hPG), homeostatic model assessment for insulin resistance (HOMA-IR), glycosylated hemoglobin (HbA1c)/total cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL-C), low density lipoprotein (LDL-C), body mass index (BMI). After screening, a total of 10 studies (706 participants) remained. Fenugreek significantly reduced FBG, 2-hPG, and HbA1c, but it did not significantly decrease HOMA-IR. Moreover, it significantly improved TC, TG, and HDL-C, while there were no significant differences in LDL-C and BMI. Hepatic or renal toxicity was not observed, and there were no severe adverse events associated with fenugreek despite mild gastrointestinal side effects in some studies. In conclusion, fenugreek improves overall glycemic control parameters and lipid profile safely.
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Programmed death-ligand 1 (PD-L1) is constitutively expressed by hypoxia-inducible factor 2α (HIF2α). It can be induced by interferon gamma (IFNγ) signaling in clear cell renal cell carcinoma (ccRCC). Clinical trials of metastatic ccRCCs have suggested that a canonical IFNγ signature is a better biomarker for therapeutic response to immune checkpoint inhibitors (ICIs) than PD-L1 expression levels in tumor cells. To understand the therapeutic response to ICIs according to PD-L1 expression levels, we analyzed transcriptional regulation of the PD-L1 promoter by HIF2α and IFNγ-inducible interferon regulatory factor-1 (IRF-1) in ccRCC cells. Here, we present two ccRCC cell models showing differential PD-L1 expression levels in response to IFNγ and hypoxia. Analysis of The Cancer Genome Atlas RNA-sequencing data revealed that PD-L1 expression correlated with JAK2 and STAT1 expression of the canonical IFNγ signature in ccRCC tissues. Upon IFNγ stimulation, PD-L1 was induced by sequential activation of JAK2/STAT1/IRF-1 signaling in both WT- and Mut- VHL ccRCC cells. IFNγ activated the IRF-1α site of the PD-L1 promoter. The IFNγ-mediated increase of PD-L1 expression in Mut-VHL cells was 4.8-fold greater than that in WT-VHL cells. Under normoxia condition, PD-L1 expression in Mut-VHL cells was significantly higher than that in WT-VHL cells due to high basal HIF2α expression. Under hypoxia condition, PD-L1 expression in WT-VHL cells was induced up to 1.8-fold through activation of hypoxia-response elements 2 and 3. In contrast, although PD-L1 in Mut-VHL cells was already highly expressed in the basal state through activation of hypoxia-response elements 2, 3, and 4, it was no longer induced by hypoxia. In conclusion, Mut-VHL ccRCC cells displayed higher PD-L1 expression due to high basal HIF2α expression and a stronger response to IFNγ stimulation than WT-VHL cells. The fact that HIF2α antagonists can potentially reduce PD-L1 expression levels should be considered in ICI combination therapy.
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Carcinoma de Células Renais , Neoplasias Renais , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Carcinoma de Células Renais/patologia , Linhagem Celular Tumoral , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Hipóxia , Interferon gama/metabolismo , Neoplasias Renais/metabolismo , Masculino , Proteína Supressora de Tumor Von Hippel-Lindau/genética , Proteína Supressora de Tumor Von Hippel-Lindau/metabolismoRESUMO
Transdifferentiation (or activation) of hepatic stellate cells (HSCs) to myofibroblasts is a key event in liver fibrosis. Activated HSCs in the tumor microenvironment reportedly promote tumor progression. This study analyzed the effect of an inhibitor of HSC activation, retinol-binding protein-albumin domain III fusion protein (R-III), on protumorigenic functions of HSCs. Although conditioned medium collected from activated HSCs enhanced the migration, invasion, and proliferation of the hepatocellular carcinoma cell line Hepa-1c1c7, this effect was not observed in Hepa-1c1c7 cells treated with conditioned medium from R-III-exposed HSCs. In a subcutaneous tumor model, larger tumors with increased vascular density were formed in mice transplanted with Hepa-1c1c7+HSC than in mice transplanted with Hepa-1c1c7 cells alone. Intriguingly, when Hepa-1c1c7+HSC-transplanted mice were injected intravenously with R-III, a reduction in vascular density and extended tumor necrosis were observed. In an orthotopic tumor model, co-transplantation of HSCs enhanced tumor growth, angiogenesis, and regional metastasis accompanied by increased peritumoral lymphatic vessel density, which was abolished by R-III. In vitro study showed that R-III treatment affected the synthesis of pro-angiogenic and anti-angiogenic factors in activated HSCs, which might be the potential mechanism underlying the R-III effect. These findings suggest that the inhibition of HSC activation abrogates HSC-induced tumor angiogenesis and growth, which represents an attractive therapeutic strategy.
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Carcinoma Hepatocelular/patologia , Células Estreladas do Fígado/efeitos dos fármacos , Neoplasias Hepáticas/patologia , Proteínas Recombinantes de Fusão/farmacologia , Albuminas/química , Albuminas/farmacologia , Albuminas/uso terapêutico , Animais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Carcinoma Hepatocelular/irrigação sanguínea , Carcinoma Hepatocelular/terapia , Transformação Celular Neoplásica/efeitos dos fármacos , Células Cultivadas , Regulação para Baixo/efeitos dos fármacos , Feminino , Células Estreladas do Fígado/fisiologia , Neoplasias Hepáticas/irrigação sanguínea , Neoplasias Hepáticas/terapia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Neovascularização Patológica/genética , Neovascularização Patológica/prevenção & controle , Domínios e Motivos de Interação entre Proteínas/fisiologia , Proteínas Recombinantes de Fusão/uso terapêutico , Proteínas de Ligação ao Retinol/farmacologia , Proteínas de Ligação ao Retinol/uso terapêutico , Microambiente Tumoral/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Introduction: Owing to the coronavirus disease 19 pandemic, the demand for telemedicine has increased. However, the awareness of and experience with telemedicine among the Korean population have not been investigated. Therefore, we examined Korean outpatients' experience with and awareness of telemedicine. Methods: From December 2020 to March 2021, we conducted a survey exploring the awareness of and experience with telemedicine of outpatients who were consecutively enrolled by family physicians from four hospitals. The participants completed questionnaires on sociodemographic characteristics and knowledge, experience, satisfaction, preference, and future considerations concerning telemedicine. We evaluated factors associated with satisfaction with telemedicine experiences using multivariate logistic regression analysis. Results: Among the 563 study participants, 364 participants had experience with telemedicine. More than 95% of the telemedicine visits were performed by telephone consultation, and the most common disease type for telemedicine visits was chronic diseases (67.5%). Overall, 82.4% of the participants were satisfied with telemedicine. More than 90% of the participants were satisfied with telemedicine in terms of saving time and money relative to hospital visits, no risk of infection, and convenience. According to the multivariate logistic regression analysis, adults aged ≥65 years (odds ratio [OR] 3.53, 95% confidence interval [CI] 1.44-8.68), residents of a metropolitan city (OR 6.8, 95% CI 1.41-32.55), and those with knowledge of telemedicine (OR 2.96, 95% CI 1.21-7.26) were more likely to be satisfied with their telemedicine experience, compared with their counterparts. For chronic diseases, participants with telemedicine experience were significantly more likely to prefer telemedicine for revisits, compared with those with no telemedicine experience. Nonetheless, most respondents recognized that telemedicine requires improvement. Conclusions: Most Korean outpatients showed high satisfaction with telemedicine. Telemedicine may be considered in various medical situations in the future. Therefore, building a practical system for telemedicine and changes in the medical environment are required.
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Feline calicivirus (FCV) is a common cause of upper respiratory tract disease in cats. In this study, the complete genome sequence of FCV 14Q315, which was detected from a dead domestic cat with a hemorrhagic-like disease, was analyzed to identify the genetic characteristics. The FCV 14Q315 genome was 7,684 bp. Phylogenetic analyses based on the ORF1, ORF2, and ORF3 sequences indicated that FCV 14Q315 is more closely related to FCV 15D022 than to other FCV strains. ORF1 of FCV 14Q315 shared high sequence similarity with ORF1 of FCVs 15D022 and UTCVM-H1. We further evaluated genetic recombination in ORF1 of FCV 14Q315 and detected intergenic recombination between p30 and the ORF1/ORF2 junction with high significance. Particularly, the non-recombination region in ORF1 of FCV 14Q315 showed high sequence similarity with FCVs GX2019, CH-JL2, and 15D022. The recombination region in ORF1 of FCV 14Q315 showed the highest similarity with FCV UTCVM-H1, which is associated with a hemorrhagic-like disease. The results suggest that the UTCVM-H1-like FCV was introduced into the Republic of Korea and presumably recombined with Korean FCVs by occasional mixed infections. In addition, the Korean FCV strains were located in several phylogenetic clusters with marked genetic diversity in the ORF2 region. These results imply that Korean FCVs possess high genetic diversity owing to mutations and recombination. Furthermore, it is possible that certain FCVs caused cyclical infections in the Korean cat population based on a phylogenetic analysis of FCVs isolated at different time points. Keywords: calicivirus; virulent systemic feline calicivirus; recombination; hemorrhagic-like disease.
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Infecções por Caliciviridae , Calicivirus Felino , Animais , Infecções por Caliciviridae/veterinária , Calicivirus Felino/genética , Gatos , Humanos , Filogenia , Recombinação Genética , República da CoreiaRESUMO
We present an optical architecture for a scanning lidar in which a digital micromirror device (DMD) is placed at an intermediate image plane in a receiver to decouple the trade-offs between scan angle, scan speed, and aperture size of the lidar's transmitter and receiver. In the architecture, the transmitter with a galvo mirror and the receiver with a DMD scan the horizontal and vertical fields of view, respectively, to enable an increased field of view of 50°, centimeter transmitter beam diameter, and video frame rate range finding captures. We present our optimized system and discuss the adjustable parameter trade-offs.
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Self-rated health, a valid measure of general health, is influenced by family dynamics and depression. In this study, using data from the Family Cohort Study in Primary Care, we investigated whether depressive mood moderated the association between family communication and self-rated health in married couples. Among the 520 couples in the cohort, we cross-sectionally analyzed the responses of 420 couples (840 participants) who provided answers to the Center for Epidemiologic Studies Depression Scale, the Family Communication Scale of the Family Adaptation and Cohesion Evaluation Scale-IV, and a self-rated health question. Hierarchical regression analyses were performed to evaluate the interactions between depressive mood and family communication on self-rated health. High levels of family communication were associated with better self-rated health (r = -.16, p < .01), and that depressive mood moderated the association between family communication and self-rated health (ß = .10, p = .008). Specifically, the association between family communication and self-rated health was significant only when levels of depressive mood were low (ß = -.175, p = < .001), and the association was lost when levels of depressive mood were high (ß = -.031, p = .446). High levels of depressive mood weakened the positive association between family communication and self-rated health. Our findings highlight the significant influence of depressive symptoms on family dynamics and health among patients in primary care.
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Comunicação , Depressão/psicologia , Relações Familiares , Nível de Saúde , Cônjuges/psicologia , Adulto , Estudos de Coortes , Autoavaliação Diagnóstica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Atenção Primária à SaúdeRESUMO
Inulae Flos, the flower of Inula britannica L., is used as a dietary supplement, beverage, and medicine in East Asia. In this study, we evaluated the gastroprotective effects of Inulae Flos extract (IFE) against gastric mucosal lesions induced by hydrochloric acid (HCl)/ethanol in rats and explored its potential mechanisms by measuring antioxidant enzyme activity, mucus secretion, and prostaglandin E2 (PGE2) levels. Pretreatment with IFE at doses of 100 and 300 mg/kg significantly inhibited gastric lesions in HCl/ethanol-treated rats. IFE increased the activities of superoxide dismutase and catalase and the levels of glutathione and PGE2 in gastric tissues. The administration of IFE also significantly increased the gastric wall mucus contents in HCl/ethanol-induced gastric lesions. These findings suggest that IFE has gastroprotective effects against HCl/ethanol-induced gastric lesions and exerts these effects through increased antioxidant levels and gastric mucus secretion. Inulae Flos may be a promising agent for the prevention and treatment of gastritis and gastric ulcers.
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Flores/química , Inula/química , Extratos Vegetais/farmacologia , Substâncias Protetoras/farmacologia , Úlcera Gástrica/tratamento farmacológico , Animais , Antioxidantes/metabolismo , Catalase/metabolismo , Dinoprostona/metabolismo , Modelos Animais de Doenças , Etanol/toxicidade , Suco Gástrico/efeitos dos fármacos , Mucosa Gástrica/efeitos dos fármacos , Mucosa Gástrica/patologia , Glutationa Peroxidase/metabolismo , Ácido Clorídrico/toxicidade , Masculino , Malondialdeído/metabolismo , Muco/metabolismo , Extratos Vegetais/administração & dosagem , Substâncias Protetoras/administração & dosagem , Ratos Sprague-Dawley , Úlcera Gástrica/induzido quimicamente , Úlcera Gástrica/patologia , Superóxido Dismutase/metabolismoRESUMO
We investigate the partial derivative approach to the change of scale formula for the functon space integral and we investigate the vector calculus approach to the directional derivative on the function space and prove relationships among the Wiener integral and the Feynman integral about the directional derivative of a Fourier transform.
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In this paper, we propose an intrusion detection system based on the estimation of the Rényi entropy with multiple orders. The Rényi entropy is a generalized notion of entropy that includes the Shannon entropy and the min-entropy as special cases. In 2018, Kim proposed an efficient estimation method for the Rényi entropy with an arbitrary real order α . In this work, we utilize this method to construct a multiple order, Rényi entropy based intrusion detection system (IDS) for vehicular systems with various network connections. The proposed method estimates the Rényi entropies simultaneously with three distinct orders, two, three, and four, based on the controller area network (CAN)-IDs of consecutively generated frames. The collected frames are split into blocks with a fixed number of frames, and the entropies are evaluated based on these blocks. For a more accurate estimation against each type of attack, we also propose a retrospective sliding window method for decision of attacks based on the estimated entropies. For fair comparison, we utilized the CAN-ID attack data set generated by a research team from Korea University. Our results show that the proposed method can show the false negative and positive errors of less than 1% simultaneously.
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PURPOSE: The aim of the current trial was to assess the efficacy of on demand clomipramine 15 mg administered before sexual intercourse for the treatment of premature ejaculation. MATERIALS AND METHODS: A total of 159 patients at 5 centers in Korea were randomly assigned to 2 groups. The first group of 53 men received placebo and the second group of 106 received clomipramine 15 mg for 12 weeks. All patients were evaluated at the beginning of the study and every 4 weeks thereafter. Patients were instructed to ingest a tablet approximately 2 to 6 hours before sexual intercourse. Efficacy was assessed by scores on the IELT (Intravaginal Ejaculation Latency Time) and the PEDT (Premature Ejaculation Diagnostic Tool). RESULTS: Analyses of the IELT fold change in each group in the intent to treat population revealed that the IELT of the clomipramine 15 mg group was significantly increased 12 weeks after administration compared with the placebo group (mean ± SD 4.40 ± 5.29 vs 2.68 ± 2.03, p <0.05). The IELT fold change in the per protocol population also significantly differed between the clomipramine 15 mg group and the placebo group (mean 4.66 ± 5.64 vs 2.80 ± 2.19, p <0.05). There was a significant difference in the PEDT scores between the 2 groups (p <0.001). The most commonly reported adverse events were nausea in 15.7% of men and dizziness in 4.9%. Adverse events were mild to moderate in severity. CONCLUSIONS: The results of this multicenter, randomized, double-blind, placebo controlled, fixed dose clinical phase III study suggest that administering clomipramine 15 mg on demand to treat premature ejaculation is effective and safe.
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Clomipramina/administração & dosagem , Ejaculação Precoce/tratamento farmacológico , Inibidores Seletivos de Recaptação de Serotonina/administração & dosagem , Adulto , Idoso , Método Duplo-Cego , Esquema de Medicação , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Adulto JovemRESUMO
Bats have been widely known as natural reservoir hosts of zoonotic diseases, such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) caused by coronaviruses (CoVs). In the present study, we investigated the whole genomic sequence of a SARS-like bat CoV (16BO133) and found it to be 29,075 nt in length with a 40.9% G+C content. Phylogenetic analysis using amino acid sequences of the ORF 1ab and the spike gene showed that the bat coronavirus strain 16BO133 was grouped with the Beta-CoV lineage B and was closely related to the JTMC15 strain isolated from Rhinolophus ferrumequinum in China. However, 16BO133 was distinctly located in the phylogenetic topology of the human SARS CoV strain (Tor2). Interestingly, 16BO133 showed complete elimination of ORF8 regions induced by a frame shift of the stop codon in ORF7b. The lowest amino acid identity of 16BO133 was identified at the spike region among various ORFs. The spike region of 16BO133 showed 84.7% and 75.2% amino acid identity with Rf1 (SARS-like bat CoV) and Tor2 (human SARS CoV), respectively. In addition, the S gene of 16BO133 was found to contain the amino acid substitution of two critical residues (N479S and T487 V) associated with human infection. In conclusion, we firstly carried out whole genome characterization of the SARS-like bat coronavirus discovered in the Republic of Korea; however, it presumably has no human infectivity. However, continuous surveillance and genomic characterization of coronaviruses from bats are necessary due to potential risks of human infection induced by genetic mutation.
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Betacoronavirus/isolamento & purificação , Quirópteros/virologia , Genoma Viral , Animais , Betacoronavirus/classificação , Betacoronavirus/genética , Humanos , Tipagem Molecular , Filogenia , República da Coreia , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/genética , Análise de Sequência de Proteína , Especificidade da Espécie , Sequenciamento Completo do GenomaRESUMO
We designed novel thermally activated delayed fluorescence (TADF) host molecules for blue electrophosphorescence by combining electron donor acridine derivatives and the electron acceptor 3,4,5-triphenyl-1,2,4-triazole (TPT) unit into a single molecule based on density functional theory (DFT). We obtain the energies of the first singlet (S1) and first triplet (T1) excited states of TADF materials by performing DFT and time-dependent DFT (TD-DFT) calculations on the ground state using dependence on charge transfer amounts for the optimal Hartree-Fock percentage in the exchange-correlation of TD-DFT. The host molecules retained high triplet energy and showed great potential for use in blue phosphorescent organic light-emitting diodes. The results showed that these molecules are promising TADF host materials because they have a low barrier to hole and electron injection, a balanced charge transport for both holes and electrons, and a small energy difference (ΔEST) between the S1 and T1 states.
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Novel thermally activated delayed fluorescence (TADF) materials with 9,9-dimethyl-9H-thioxanthene 10,10-dioxide (SB) as an electron acceptor and andspiro[acridine-9,9'-fluorene] (D1) and spiro[acridine-9,9'-xanthene] (D2) as electron donors (2D1-SB and 2D2-SB) and their characteristics were compared with those of a reference material using 9,9-dimethylacridin (DMAC) as an electron donor (2DMAC-SB) for blue organic light-emitting diodes (OLEDs). We obtain the energies of the first singlet (S1) and first triplet (T1) excited states of TADF materials by performing density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations on the ground state using the dependence on charge transfer amounts for the optimal Hartree-Fock percentage in the exchange-correlation of TD-DFT. We show that 2D2-SB would be a suitable blue OLED emitter because it has sufficiently small value (0.064 eV) of energy difference (ΔEST) between the S1 and T1 states, which is favorable for a reverse inter system crossing process from the T1 to S1 states and an emission wavelength of 439.5 nm with sufficiently large oscillator strength (F) value.
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We designed novel thermally activated delayed fluorescence (TADF) host molecules for blue electrophosphorescence by combining the electron donor 1,3-Bis(N-carbazolyl)benzene (mCP) unit and the electron acceptor diphenylphosphine oxide-4-(triphenylsilyl) phenyl (TSPO1) unit in a single molecule based on density functional theory. We obtained the energies of the first singlet (S1) and the first triplet (T1) excited states of the TADF materials by performing density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations to the ground state using dependence on charge transfer amounts for the optimal Hartree-Fock percentage in the exchange-correlation of TD-DFT. Using DFT and TD-DFT calculations, the large separation between the HOMO and LUMO caused a small difference in energy (ΔEST) between the S1 and T1 states. The host molecules retained high triplet energy and showed great potential for use in blue phosphorescent organic light-emitting diodes. The results showed that these molecules are promising TADF host materials because they have a low barrier to hole and electron injection, balanced charge transport for both holes and electrons, and small ΔEST.
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We designed novel thermally activated delayed fluorescence (TADF) materials with benzofuro[2,3-b]pyridine (BFP) as an electron acceptor and spiro[acridine-9,9'-fluorene] (D1) and spiro[acridine-9,9'-xanthene] (D2) as electron donors (BFP-D1 and BFP-D2) and compared their characteristics with those of a reference material using 9-phenylcarbazole (pCz) as an electron donor (BFP-pCz) for blue organic light-emitting diodes (OLEDs). Using density functional theory (DFT) and time-dependent DFT calculations, we obtained the electron distributions of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), and the energies of the lowest singlet (S1) and lowest triplet (T1) excited states. The calculated difference in energy (ΔEST) between the S1 and T1 states of BFP-D1 (0.06 eV) and BFP-D2 (0.07 eV) was smaller than that of BFP-pCz (0.89 eV). The results showed that BFP-D2 is a suitable blue OLED emitter because it has sufficiently small ΔEST values, which is favorable in a reverse-intersystem process crossing from the T1 state to S1 states, as well as an emission wavelength of 465.9 nm.
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Novel blue thermally activated delayed fluorescence (TADF) emitters, D1-DPS and D2-DPS, were designed and synthesized. Diphenyl sulfone (DPS) group functioned as a common acceptor, and it combined with each of two different spiro-acridine groups, D1 and D2. The calculated energy differences (ΔEST) of the singlet and triplet excited states of D1-DPS (0.062 eV) and D2-DPS (0.128 eV) had sufficiently small ΔEST values, which is favorable in the thermally activated reverse intersystem crossing (RISC) process from the T1 state to the S1 state. A device doped 10 wt% of D2-DPS with ADN host material, obtained 5.05% of external quantum efficiency with deep-blue emission having CIExy coordinates of (0.152, 0.065). The results showed that these molecules are promising host-free TADF deep-blue emitters by inhibiting concentration quenching.