Enhanced Stability and Highly Bright Electroluminescence of AgInZnS/CdS/ZnS Quantum Dots through Complete Isolation of Core and Shell via a CdS Interlayer.

An approach for synthesizing AgInZnS/CdS/ZnS core-shell-shell quantum dots (QDs) that demonstrate exceptional stability and electroluminescence (EL) performance is introduced. This approach involves incorporating a cadmium sulfide (CdS) interlayer between an AgInZnS (AIZS) core and a zinc sulfide (ZnS) shell to prevent the diffusion of Zn ions into the AIZS core and the cation exchange at the core-shell interface. Consequently, a uniform and thick ZnS shell, with a thickness of 2.9 nm, is formed, which significantly enhances the stability and increases the photoluminescence quantum yield (87.5%) of the QDs. The potential for AIZS/CdS/ZnS QDs in electroluminescent devices is evaluated, and an external quantum efficiency of 9.6% in the 645 nm is achieved. These findings highlight the importance of uniform and thick ZnS shells in improving the stability and EL performance of QDs.

1.3-µm identical active electro-absorption modulated laser with quantum well intermixed passive waveguide.

Quantum well intermixing (QWI) is an effective method for simple and well-defined monolithic integration of photonic devices. We introduce an identical-active electro-absorption modulated laser (IA-EML) with optimized QWI, which is applied to reduce the absorptive waveguide region. To determine the optimal intermixed IA-EML structure, we conduct a comparative analysis between the cases of an IA-EML with only an intermixed waveguide region and with both intermixed waveguide and electro-absorption modulator (EAM) regions, as well as the case without QWI. The results reveal that the intermixed region effectively inhibits the absorption in the waveguide. In particular, the IA-EML with only waveguide intermixing exhibits superior modulation characteristics with low driving voltages and a high extinction ratio. Our work provides an attractive approach for suppressing the absorptive waveguide region in the IA-EML to enhance modulation performance and to develop photonic integrated circuits with a simplified process.

Clinical Outcomes of Clipping and Coil Embolization for Ruptured Intracranial Aneurysms Categorized by Region and Hospital Size: A Nationwide Cohort Study in Korea.

BACKGROUND: To analyze the outcomes of clipping and coiling for ruptured intracranial aneurysms (RIAs) based on data from the National Health Insurance Service in South Korea, with a focus on variations according to region and hospital size. METHODS: This study analyzed the one-year mortality rates for patients with RIAs who underwent clipping or coiling in 2018. Coiling was further categorized into non-stent assisted coiling (NSAC) and stent assisted coiling (SAC). Hospitals were classified as tertiary referral general hospitals (TRGHs), general hospitals (GHs), or semi-general hospitals (sGHs) based on size. South Korea's administrative districts were divided into 15 regions for analysis. RESULTS: In 2018, there were 2,194 (33.1%) clipping procedures (TRGH, 985; GH, 827; sGH, 382) and 4,431 (66.9%) coiling procedures (TRGH, 1,642; GH, 2076; sGH, 713) performed for RIAs treatment. Among hospitals performing more than 20 treatments, the one-year mortality rates following clipping or coiling were 11.2% and 16.0%, respectively, with no significant difference observed. However, there was a significant difference in one-year mortality between NSAC and SAC (14.3% vs. 19.5%, P = 0.034), with clipping also showing significantly lower mortality compared to SAC (P = 0.019). No significant differences in other treatment modalities were observed according to hospital size, but clipping at TRGHs had significantly lower mortality than at GHs (P = 0.042). While no significant correlation was found between the number of treatments and outcomes at GHs, at TRGHs, a higher volume of clipping procedures was significantly associated with lower total mortality (P = 0.023) and mortality after clipping (P = 0.022). CONCLUSION: Using Korea NHIS data, mortality rates for RIAs showed no significant variation by hospital size due to coiling's prevalence. However, differences in clipping outcomes by hospital size and volume in TRGH highlight the need for national efforts to improve clipping skills and standardization. Additionally, the higher mortality rate with SAC emphasizes the importance of precise indications for its application.

Impact of interstitial lung abnormalities on postoperative pulmonary complications and survival of lung cancer.

BACKGROUND: Interstitial lung abnormalities (ILAs) are associated with the risk of lung cancer and its mortality. However, the impact of ILA on treatment-related complications and survival in patients who underwent curative surgery is still unknown. RESEARCH QUESTION: This study aimed to evaluate the significance of the presence of computed tomography-diagnosed ILA and histopathologically matched interstitial abnormalities on postoperative pulmonary complications (PPCs) and the long-term survival of patients who underwent surgical treatment for lung cancer. STUDY DESIGN AND METHODS: A matched case-control study was designed to compare PPCs and mortality among 50 patients with ILA, 50 patients with idiopathic pulmonary fibrosis (IPF) and 200 controls. Cases and controls were matched by sex, age, smoking history, tumour location, the extent of surgery, tumour histology and pathological TNM stage. RESULTS: Compared with the control group, the OR of the prevalence of PPCs increased to 9.56 (95% CI 2.85 to 32.1, p<0.001) in the ILA group and 56.50 (95% CI 17.92 to 178.1, p<0.001) in the IPF group. The 5-year overall survival (OS) rates of the control, ILA and IPF groups were 76% (95% CI 71% to 83%), 52% (95% CI 37% to 74%) and 32% (95% CI 19% to 53%), respectively (log-rank p<0.001). Patients with ILA had better 5-year OS than those with IPF (log-rank p=0.046) but had worse 5-year OS than those in the control group (log-rank p=0.002). CONCLUSIONS: The presence of radiological and pathological features of ILA in patients with lung cancer undergoing curative surgery was associated with frequent complications and decreased survival.

Regulation of Dihydropyrimidinase-like 3 Gene Expression by MicroRNAs in PC12 Cells with Induced Ischaemia and Hypothermia.

Although hypothermic treatment has been reported to have some beneficial effects on ischaemia at the clinical level, the mechanism of ischaemia suppression by hypothermia remains unclear due to a lack of mechanism understanding and insufficient data. The aim of this study was to isolate and characterize microRNAs specifically expressed in ischaemia-hypothermia for the dihydropyrimidinase-like 3 (Dpysl3) gene. PC12 cells were induced with CoCl2 for chemical ischaemia and incubated at 32 ℃ for hypothermia. In ischaemia-hypothermia, four types of microRNAs (miR-106b-5p, miR-194-5p, miR-326-5p, and miR-497-5p) were highly related to the Dpysl3 gene based on exosomal microRNA analysis. Dpysl3 gene expression was up-regulated by miR-497-5p but down-regulated by miR-106b-5p, miR-194-5p and miR-326-5p. Our results suggest that these four microRNAs are involved in the regulation of Dpysl3 gene expression. These findings provide valuable clues that exosomal microRNAs could be used as therapeutic targets for effective treatment of ischaemia.

Fabrication of Colloidal Cesium Metal Halide (CsMX: M = Fe, Co, and Ni) Nanoparticles and Assessment of Their Thermodynamic Stability by DFT Calculations.

We synthesized colloidal cesium metal halide CsMX (M = Fe, Co, Ni; X = Cl, Br) nanoparticles (NPs) and assessed their crystal stability by density functional theory (DFT) calculations. We successfully synthesized Cs3FeCl5, Cs3FeBr5, Cs3CoCl5, Cs3CoBr5, CsNiCl3, and CsNiBr3 NPs. CsMX NPs with Fe and Co exhibited Cs3M1X5 and Cs2M1X4 structures depending on the reaction conditions; however, CsNiX NPs exhibited only the CsNiX3 structure. The differences in structural stability by central metal ions were explained using spin-polarized DFT calculations. The analysis revealed tetragonal Cs3M1X5 and orthorhombic Cs2M1X4 structures to have similar thermodynamic stabilities in the case of Fe and Co, whereas the hexagonal CsMX3 structure in the case of Ni was the most stable. Moreover, the calculation results were the same as the experimental results. In particular, cobalt-related Cs3CoBr5 NPs easily developed into Cs2CoCl4 nanorods with an increase in temperature.

Preoperative Helical Dynamic Enhanced Multidetector Row Computed Tomography: Can It Be a Prognostic Indicator in Early-Stage Non-small Cell Lung Cancer?

OBJECTIVE: This study aimed to investigate the prognostic significance of dynamic contrast-enhanced computed tomography in patients with stage IA non-small cell lung cancer (NSCLC). METHODS: We retrospectively enrolled 139 patients (77 men, 62 women; mean age, 59 years) with stage IA NSCLC who underwent dynamic contrast-enhanced computed tomography. Data on age, pathologic subtype, peak enhancement, and net enhancement of primary lung cancer were collected and correlated with 5-year survival. RESULTS: Peak enhancement had a significant correlation with overall survival in the univariable analysis (hazard ratio [HR], 1.18, confidence interval [CI], 1.01-1.38; P = 0.04) and in the multivariable analysis (HR, 1.19; CI, 1.01-1.39; P = 0.04). Patients with peak enhancement of 90 Hounsfield unit or higher had a significantly increased risk of death compared with patients with less enhancement after curative surgery (HR, 4.15; CI, 1.23-13.95; P = 0.02). CONCLUSIONS: Our study confirmed the prognostic significance of peak enhancement as an indicator for the overall survival of stage IA NSCLC.

Skin manifestations and clinical features of drug reaction with eosinophilia and systemic symptoms: a retrospective multicentre study of 125 patients.

BACKGROUND: Drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe adverse drug reaction generally accompanied by skin manifestations as the first and most frequent symptoms. However, skin manifestations and associated clinical features of DRESS have not been fully explored and evaluated. OBJECTIVES: This study aimed to describe the skin manifestations of DRESS in detail and analyse their association with demographic characteristics and extra-cutaneous clinical features. METHODS: We conducted this retrospective study on patients with DRESS diagnosed between September 2009 and August 2021 at three medical institutes and validated using the RegiSCAR score. Data regarding demographics, skin manifestations and clinical characteristics were retrieved through thorough chart reviews. RESULTS: Among 182 potential cases of DRESS, the validated 125 cases were analysed. A widespread rash extending over more than 50% of the body surface area was observed in 122 patients (97.6%) and typical facial oedema was experienced by 67 patients (53.6%). Polymorphous maculopapules were the most common rash morphology (106, 84.8%): specifically, exfoliative (59, 47.2%), urticarial (57, 45.6%) and purpuric forms (39, 31.2%) were common. Mucosal involvement was observed in 41 patients (32.8%). Patients with carboxamide antiepileptics (carbamazepine and oxcarbazepine) experienced more oedema (P = 0.014) and typical facial oedema than those with allopurinol (P = 0.021). The RegiSCAR score was higher in patients with purpura (P < 0.01). CONCLUSIONS: Skin manifestations of DRESS exhibit a wide range of skin lesions and can vary according to the culprit drugs. Early suspicion and prompt intervention are needed to improve prognosis.

The Higher Incidence of COVID-19 in Patients With Non-Tuberculous Mycobacterial Pulmonary Disease: A Single Center Experience in Korea.

The aim of our study was to investigate the incidence of and risk factors for coronavirus disease 2019 (COVID-19) in patients with non-tuberculous mycobacterial-pulmonary disease (NTM-PD). A total of 3,866 patients with NTM-PD were retrospectively identified from a single center. Compared to the general population of Korea, patients with NTM-PD had a substantially increased age-standardized incidence of COVID-19 from January 2020 to February 2021 (2.1% vs. 0.2%). The odds of being infected with COVID-19 was particularly higher in patients who received treatment for NTM-PD than in those who did not receive treatment for NTM-PD (adjusted odd ratio = 1.99, 95% confidence interval = 1.09-3.64, P = 0.026). Patients with NTM-PD might be regarded as a high-risk group for COVID-19 and may need a more proactive preventive strategy for COVID-19 and other pandemics in the future.

Short-term outcomes of a multicentre randomized clinical trial comparing laparoscopic pylorus-preserving gastrectomy with laparoscopic distal gastrectomy for gastric cancer (the KLASS-04 trial).

BACKGROUND: There remain concerns about the safety and functional benefit of laparoscopic pylorus-preserving gastrectomy (LPPG) compared with laparoscopic distal gastrectomy (LDG). This study evaluated short-term outcomes of a randomized clinical trial (RCT) comparing LPPG with LDG for gastric cancer. METHODS: The Korean Laparoendoscopic Gastrointestinal Surgery Study (KLASS)-04 trial was an investigator-initiated, open-label, parallel-assigned, superiority, multicentre RCT in Korea. Patients with cT1N0M0 cancer located in the middle third of the stomach at least 5 cm from the pylorus were randomized to undergo LPPG or LDG. Participants, care givers and those assessing the outcomes were not blinded to group assignment. Outcomes were 30-day postoperative morbidity rate and death at 90 days. RESULTS: Some 256 patients from nine institutions were randomized (LPPG 129 patients, LDG 127 patients) between July 2015 and July 2017 and outcomes for 253 patients were analysed. Postoperative complications within 30 days were seen in 19.3 and 15.5 per cent in the LPPG and LDG groups respectively (P = 0·419). Postoperative pyloric stenosis was observed in nine (7.2 per cent) and two (1·5 per cent) patients in the LPPG and LDG groups (P = 0·026) respectively. In multivariable analysis higher BMI was a risk factor for postoperative complications (odds ratio 1·17, 95 per cent c.i. 1·04 to 1·32; P = 0·011). Death at 90 days was zero in both groups. CONCLUSION: Postoperative complications and mortality was comparable in patients undergoing LPPG and LDG. Registration number: NCT02595086 (http://www.clinicaltrials.gov).

Lipidomics reveals that acupuncture modulates the lipid metabolism and inflammatory interaction in a mouse model of depression.

Depression is a serious disease that has considerable impact on lipid metabolism and inflammatory responses. Recent studies have shown that leptin, which is well known as a mediator of energy homeostasis and is a cytokine in inflammatory response, plays an important role in depression. Acupuncture is widely used to treat depression; however, the underlying mechanisms and the effect of acupuncture on depression remain poorly understood. In this study, we utilized the chronic restraint stress (CRS) induced depression model and acupuncture treatment was performed at KI10, LR8, LU8, LR4 (AP) or non-acupoint (NP). Then, lipidomics was applied to investigate the effects of acupuncture on lipid metabolism and analyze leptin signals in the brain and changes of immune markers. Acupuncture treatment at AP improved depression-like behavior in an open-field test, forced swimming test, and marble burying test. Concurrently, CRS mice treated with AP acupuncture (CRS + AP) had significantly lower levels of aspartate aminotransaminase (AST, liver injury markers) and exhibited different lipid patterns in liver lipidomic profiles. In particular, triglycerides (TGs) contributed the change of lipid patterns. Compared to the CRS mice, TGs with relatively high degrees of unsaturated fatty acids increased in the CRS + AP mice, but did not change in CRS mice treated with NP acupuncture (CRS + NP). The levels of leptin in plasma and leptin receptor positive cells in the brain (hypothalamus and hippocampus) decreased and increased, respectively, in the CRS + AP mice, while opposite patterns were exhibited in the CRS and CRS + NP mice. These results indicated that acupuncture treatment at AP attenuated leptin insensitivity in CRS mice. Additionally, expression of pro-inflammatory cytokines such as interleukin-1 beta and tumor necrosis factor-alpha were decreased in the spleen, plasma, and liver of CRS + AP mice, which was one of results of alleviation of leptin resistance. In conclusion, these results show that AP acupuncture treatment effectively alleviated the depression-like behavior, affected immune responses, and altered hepatic lipid metabolism through the attenuation of leptin insensitivity.

Diversity and genotypic analysis of tick-borne pathogens carried by ticks infesting horses in Korea.

Ticks account for an extensive range of health and welfare issues in horses. In addition, tick-borne pathogens (TBPs) limit global animal trading and equine sporting events. Here, we assess the prevalence, co-infectivity and risk factors of TBPs in horse ticks in Korea. A total of 245 hard ticks, including 103 male and 142 female adults, were obtained from horses on Jeju Island during the spring to autumn seasons of 2013-2019. All collected ticks were identified as adult Haemaphysalis longicornis. We screened and analyzed each tick for the presence of several TBPs by polymerase chain reaction (PCR) analysis. Among the 245 ticks, we detected genes for three TBPs, Candidatus Rickettsia longicornii (22.9%), Ehrlichia canis (0.4%) and Theileria luwenshuni (0.4%), while Anaplasma spp. was not detected. TBPs were most prevalent in ticks harvested during the autumn season, and more abundant in the female than male adults. This is the first report of the genera Ehrlichia, Rickettsia and Theileria in horse ticks in Korea. TBPs in horse ticks are likely a reservoir for zoonotic transmission to other animals, including humans. Our findings demonstrate the need for further understanding of the prevalence and epidemiology of TBPs in wild and domestic animals.

Higher oscillatory shear index is related to aneurysm recanalization after coil embolization in posterior communicating artery aneurysms.

BACKGROUND: The recurrence rate of posterior communicating artery (Pcom) aneurysms after endovascular treatment (EVT) is higher than that for aneurysms located in other sites. However, it is still unclear what mechanisms are responsible for the recanalization of cerebral aneurysms. In this investigation, we compared hemodynamic factors related with recanalization of Pcom aneurysms treated by endoluminal coiling using computational fluid dynamics (CFD) with high-resolution three-dimensional digital subtraction angiography images. METHODS: Twenty patients were enrolled. A double-sinogram acquisition was performed with and without contrast injection after coil embolization to get true blood vessel lumen by relatively complementing the first sinogram with the second. Adaptive Cartesian meshing was performed to produce vascular wall objects for CFD simulation. The boundary condition for inlet (ICA) was set for dynamic velocity according to the cardiac cycle (0.8 s). Hemodynamic parameters were recorded at two specific points (branching point of Pcom and residual sac). The peak pressure, peak WSS, and oscillatory shear index (OSI) were recorded and analyzed. RESULTS: The median age was 61.0 years, and 18 patients (90%) were female. During a median follow-up of 12 months, seven (35%) treated aneurysms showed recanalization. The median aneurysm volume was significantly higher, and aneurysm height and neck sizes were significantly longer in the recanalization group than those in the stable group. At the branching point of the Pcom, the peak pressure, peak WSS, or OSI did not significantly differ between the two groups. The only statistically significant hemodynamic parameter related with recanalization was the OSI at the aneurysm point. Multivariate logistic regression showed that with an increase of 0.01 OSI at the aneurysm point, the odds ratio for the aneurysm recanalization was 1.19. CONCLUSIONS: A higher OSI is related with recanalization after coil embolization for a Pcom aneurysm.

Clinical Outcomes of Clipping and Coiling in Elderly Patients with Unruptured Cerebral Aneurysms: a National Cohort Study in Korea.

BACKGROUND: We aimed to analyze outcomes of clipping and coiling in treating unruptured intracranial aneurysms (UIAs) in elderly patients and to identify the age at which perioperative risk increases based on national cohort data in South Korea. METHODS: The incidence of perioperative intracranial hemorrhage (ICRH), perioperative cerebral infarction (CI), mortality, and moderate to severe disability data of the patients who underwent coiling or clipping for UIAs were retrieved. Estimated breakpoint (EBP) was calculated to identify the age at which the risk of treatment increases. RESULTS: A total of 38,207 patients were treated for UIAs. Among these, 22,093 (57.8%) patients underwent coiling and 16,114 (42.2%) patients underwent clipping. The incidence of ICRH, requiring a secondary operation, within 3 months in patients ≥ 65 years that underwent coiling and clipping was 1.13% and 4.81%, respectively, and that of both groups assessed were significantly higher in patients ≥ 75 years (coiling, P = 0.013, relative risk (RR) 1.81; clipping, P = 0.015) than younger patients. The incidence of CI within 3 months in patients aged ≥ 65 was 13.90% and 9.19% in the coiling and clipping groups, respectively. The incidence of CI after coiling in patients aged ≥ 75 years (P < 0.001, RR 1.96) and after clipping in patients aged ≥ 70 years (P < 0.001, RR 1.76) was significantly higher than that in younger patients. The mortality rates within 1 year in patients with perioperative ICRH or CI were 2.41% and 3.39% for coiling and clipping groups, respectively, in patients ≥ 65. These rates increased significantly at age 70 in the coiling group and at age 75 for the clipping group (P = 0.012 and P < 0.001, respectively). CONCLUSION: The risk of treatment increases with age, and this risk increases dramatically in patients aged ≥ 70 years. Therefore, the treatment decisions in patients aged ≥ 70 years should be made with utmost care.

Chronic obstructive pulmonary disease and lung cancer incidence in never smokers: a cohort study.

There has been limited evidence for the association between chronic obstructive pulmonary disease (COPD) and the incidence of lung cancer among never smokers. We aimed to estimate the risk of lung cancer incidence in never smokers with COPD, and to compare it with the risk associated with smoking. This cohort study involved 338 548 subjects, 40 to 84 years of age with no history of lung cancer at baseline, enrolled in the National Health Insurance Service National Sample Cohort. During 2 355 005 person-years of follow-up (median follow-up 7.0 years), 1834 participants developed lung cancer. Compared with never smokers without COPD, the fully-adjusted hazard ratios (95% CI) for lung cancer in never smokers with COPD, ever smokers without COPD, and ever smokers with COPD were 2.67 (2.09 to 3.40), 1.97 (1.75 to 2.21), and 6.19 (5.04 to 7.61), respectively. In this large national cohort study, COPD was also a strong independent risk factor for lung cancer incidence in never smokers, implying that COPD patients are at high risk of lung cancer, irrespective of smoking status.

Prognostic factors associated with long-term mortality in 1445 patients with nontuberculous mycobacterial pulmonary disease: a 15-year follow-up study.

Limited data are available regarding the prognostic factors for patients with nontuberculous mycobacterial pulmonary disease (NTM-PD). We investigated the prognostic factors associated with long-term mortality in NTM-PD patients after adjusting for individual confounders, including aetiological organism and radiological form.A total of 1445 patients with treatment-naïve NTM-PD who were newly diagnosed between July 1997 and December 2013 were included. The aetiological organisms were as follows: Mycobacterium avium (n=655), M. intracellulare (n=487), M. abscessus (n=129) and M. massiliense (n=174). The factors associated with mortality in NTM-PD patients were analysed using a multivariable Cox model after adjusting for demographic, radiological and aetiological data.The overall 5-, 10- and 15-year cumulative mortality rates for the NTM-PD patients were 12.4%, 24.0% and 36.4%, respectively. On multivariable analysis, the following factors were significantly associated with mortality in NTM-PD patients: old age, male sex, low body mass index, chronic pulmonary aspergillosis, pulmonary or extrapulmonary malignancy, chronic heart or liver disease and erythrocyte sedimentation rate. The aetiological organism was also significantly associated with mortality: M. intracellulare had an adjusted hazard ratio (aHR) of 1.40, 95% CI 1.03-1.91; M. abscessus had an aHR of 2.19, 95% CI 1.36-3.51; and M. massiliense had an aHR of 0.99, 95% CI 0.61-1.64, compared to M. avium Mortality was also significantly associated with the radiological form of NTM-PD for the cavitary nodular bronchiectatic form (aHR 1.70, 95% CI 1.12-2.59) and the fibrocavitary form (aHR 2.12, 95% CI 1.57-3.08), compared to the non-cavitary nodular bronchiectatic form.Long-term mortality in patients with NTM-PD was significantly associated with the aetiological NTM organism, cavitary disease and certain demographic characteristics.

Graph Convolutional Networks-Based Noisy Data Imputation in Electronic Health Record.

OBJECTIVES: A deep learning-based early warning system is proposed to predict sepsis prior to its onset. DESIGN: A novel algorithm was devised to detect sepsis 6 hours prior to its onset based on electronic medical records. SETTING: Retrospective cohorts from three separate hospitals are used in this study. Sepsis onset was defined based on Sepsis-3. Algorithms are evaluated based on the score function used in the Physionet Challenge 2019. PATIENTS: Over 60,000 ICU patients with 40 clinical variables (vital signs, laboratory results) for each hour of a patient's ICU stay were used. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The proposed algorithm predicted the onset of sepsis in the preceding n hours (where n = 4, 6, 8, or 12). Furthermore, the proposed method compared how many sepsis patients can be predicted in a short time with other methods. To interpret a given result in a clinical perspective, the relationship between input variables and the probability of the proposed method were presented. The proposed method achieved superior results (area under the receiver operating characteristic curve, area under the precision-recall curve, and score) and predicted more sepsis patients in advance. In official phase, the proposed method showed the utility score of -0.101, area under the receiver operating characteristic curve 0.782, area under the precision-recall curve 0.041, accuracy 0.786, and F-measure 0.046. CONCLUSIONS: Using Physionet Challenge 2019, the proposed method can accurately and early predict the onset of sepsis. The proposed method can be a practical early warning system in the environment of real hospitals.

Full Color Tunable Aggregation-Induced Emission Luminogen for Bioimaging Based on an Indolizine Molecular Framework.

By taking advantage of a unique mechanism of aggregation-induced emission (AIE) phenomena, AIE luminogens (AIEgens) have been provided as a solution to overcome the limitations of conventional fluorophores bearing the feature of aggregation-caused quenching (ACQ) phenomena. Especially, AIEgens paved the way to develop fluorogenic probes ideal for fluorescent imaging in live cell conditions. Despite the high demand for discovery of new AIEgens, it is still challenging to find a versatile molecular platform to generate diverse AIEgens. Herein, we report a new colorful molecular framework, Kaleidolizine (KIz), as a molecular platform for AIEgen generation. The KIz system allows systematic tuning of the emission wavelength from 455 to 564 nm via perturbation of the electron density of substituents on the indolizine core. Increasing the water fraction of the KIz solution in the THF/water mixture induces the fluorescence intensity increase up to 120-fold. Crystal structure analysis, computational calculations, and solvatochromism studies suggest that a synergistic effect between the intramolecular charge transfer and restriction of intramolecular rotation acts as the AIE mechanism in the KIz system. Conjugation of the triphenylphosphonium moiety to KIz allows successful development of triphenylphosphonium (TPP)-KIz for real-time bioimaging of innate mitochondria in live cells, thereby revealing the potential of KIz as a versatile molecular platform to generate fluorogenic probes based on AIE phenomena. We do believe the KIz system could serve as a new, reliable, and generally applicable molecular platform to develop various AIEgens having desired photophysical properties along with an excellent signal-to-noise ratio and with experimental convenience especially for fluorogenic live cell imaging.

Sub-nanosecond terahertz radiation obtained with an aperiodically poled lithium niobate and organic HMQ-TMS.

We report a compact, simple source of terahertz radiation that can be tuned to well-defined frequencies spanning ∼1.4 to 10 THz, based on difference-frequency generation in an HMQ-TMS crystal. The pair of pump pulses required for this process is obtained by optical parametric generation in an aperiodically-poled lithium niobate crystal; the center wavelength of this pair of pulses is around 1.45 µm. We obtained 40 nJ THz pulses using 38 µJ, 0.85 ns pump pulses.

MHz-repetition-rate, sub-mW, multi-octave THz wave generation in HMQ-TMS.

We demonstrate the first megahertz (MHz) repetition-rate, broadband terahertz (THz) source based on optical rectification in the organic crystal HMQ-TMS driven by a femtosecond Yb:fibre laser. Pumping at 1035 nm with 30 fs pulses, we achieve few-cycle THz emission with a smooth multi-octave spectrum that extends up to 6 THz at -30 dB, with conversion efficiencies reaching 10-4 and an average output power of up to 0.38 mW. We assess the thermal damage limit of the crystal and conclude a maximum fluence of ∼1.8 mJ·cm-2 at 10 MHz with a 1/e2 pump beam diameter of 0.10 mm. We compare the performance of HMQ-TMS with the prototypical inorganic crystal gallium phosphide (GaP), yielding a tenfold electric field increase with a peak on-axis field strength of 7 kV·cm-1 and almost double the THz bandwidth. Our results further demonstrate the suitability of organic crystals in combination with fibre lasers for repetition-rate scaling of broadband, high-power THz sources for time-domain spectroscopic applications.