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In this paper, the effects of the combination of solvents on the uniformity of a dried emitting layer and on device performance were studied. Green emitter inks with various solvents were prepared, and it was seen that good film uniformity of printed layers could be obtained with a solvent mixture with different boiling points, which reduced the coffee ring effect on a dried surface. During the inkjet process, the drop injection condition aiming was also controlled for better drop-to-drop spacing and reduction of the line-edge roughness. Printed patterns of a small molecular/polymer hybrid emitting layer, composed of the chlorobenzene-dichlorobenzene solvent mixture, showed significantly reduced roughness of the microscopic surface and improved efficiency of the inkjet device, at levels nearly comparable to those of spin-coated patterns. A suitable hole transport layer (HTL) was also further developed as an interfacial material, prior to the solution processing of the emitter. The cross-linkable HTL was composed of triphenylamine as the cross-linking unit and a fluorene-based compound. At the optimized condition of the solvent formulation, printed droplets within 100 µm× 300 µm pixels formed a uniform stripe without remarkable coffee-ring defects and line-edge surface roughness.

In the present article, the rheological responses and dispersion stability of magnetorheological (MR) fluids were investigated experimentally. Suspensions of magnetite and carbonyl iron particles were prepared as model MR fluids. Under an external magnetic field (H0) and a steady shear flow, the yield stress depends upon H03/2. The Yield stress depended on the volume fraction of the particle (φ) linearly only at low concentration and increased faster at high fraction. Rheological behavior of MR fluids subjected to a small-strain oscillatory shear flow was investigated as a function of the strain amplitude, frequency, and the external magnetic field. In order to improve the stability of MR fluid, ferromagnetic Co-γ-Fe2O3 and CrO2 particles were added as the stabilizing and thickening agent in the carbonyl iron suspension. Such needle-like particles seem to play a role in the steric repulsion between the relatively large carbonyl iron particles, resulting in improved stability against rapid sedimentation of dense iron particles. Furthermore, the additive-containing MR suspensions exhibited larger yield stress, especially at higher magnetic field strength.

We fabricated W-doped In 2 O 3 (IWO) films at room temperature on a flexible PET substrate using an in-line arc plasma ion plating system for application as flexible transparent conducting electrodes (FTCEs) in flexible organic light emitting diodes (OLEDs) and quantum dots light emitting diodes (QDLEDs). Due to the high-energy flux of the sublimated ions generated from the plasma region, the IWO films showed a well-developed crystalline structure with a low sheet resistance of 36.39 Ohm/square and an optical transmittance of 94.6% even though they were prepared at room temperature. The low sheet resistance of the IWO film processed at room temperature is attributed to the high mobility (59 cm 2 /V-s) in the well-developed crystalline structure of the ion-plated IWO film and screening effect of W dopants. In addition, the better adhesion of the ion-plated IWO film on the PET substrate led to small critical outer and inner bending radii of 6 and 3 mm, respectively, against substrate bending. Due to the low sheet resistance, high optical transmittance, better crystallinity, better adhesion, and outstanding flexibility of the ion-plated IWO films, the flexible OLEDs and QDLEDs with the IWO electrodes showed better performances than flexible OLEDs and QDLEDs with sputtered flexible ITO anodes. This indicates that in-line arc plasma ion plating is a promising large area coating technique to realize room temperature processed high-quality FTCEs for flexible OLEDs and QDLEDs.

We fabricated W-doped In O (IWO) films at room temperature on a flexible PET substrate using an in-line arc plasma ion plating system for application as flexible transparent conducting electrodes (FTCEs) in flexible organic light emitting diodes (OLEDs) and quantum dots light emitting diodes (QDLEDs). Due to the high-energy flux of the sublimated ions generated from the plasma region, the IWO films showed a well-developed crystalline structure with a low sheet resistance of 36.39 Ohm/square and an optical transmittance of 94.6% even though they were prepared at room temperature. The low sheet resistance of the IWO film processed at room temperature is attributed to the high mobility (59 cm /V-s) in the well-developed crystalline structure of the ion-plated IWO film and screening effect of W dopants. In addition, the better adhesion of the ion-plated IWO film on the PET substrate led to small critical outer and inner bending radii of 6 and 3 mm, respectively, against substrate bending. Due to the low sheet resistance, high optical transmittance, better crystallinity, better adhesion, and outstanding flexibility of the ion-plated IWO films, the flexible OLEDs and QDLEDs with the IWO electrodes showed better performances than flexible OLEDs and QDLEDs with sputtered flexible ITO anodes. This indicates that in-line arc plasma ion plating is a promising large area coating technique to realize room temperature processed high-quality FTCEs for flexible OLEDs and QDLEDs.

Visuospatial memory impairment is a common symptom of Alzheimer's disease; however, conventional visuospatial memory tests are insufficient to fully reflect visuospatial memory impairment in daily life. To address patients' difficulties in locating and recalling misplaced objects, we introduced a novel visuospatial memory test, the Hidden Objects Test (HOT), conducted in a virtual environment. We categorized HOT scores into prospective memory, item free-recall, place free-recall, item recognition, and place-item matching scores. To validate the VR memory test, we compared HOT scores among individuals with Alzheimer's disease (AD), amnestic mild cognitive impairment (aMCI), and normal controls (NC), and also compared these scores with those of conventional neuropsychological tests. We tracked the participants' movement paths in the virtual environment and assessed basic features, such as total distance, duration, and speed. Additionally, we performed walking trajectory pattern mining such as outlier and stay-point detection. We designed and implemented the HOT to simulate a house's living room and assess participants' ability to locate hidden objects. Our preliminary results showed that the total HOT score differed among 17 patients with AD, 14 with aMCI, and 15 NC (  < 0.001). The total HOT score correlated positively with conventional memory test scores (  < 0.001). Walking trajectories showed that patients with AD and aMCI wandered rather than going straight to the hidden objects. In terms of basic features, the total duration was significantly greater in AD than in NC (  = 0.008). In terms of trajectory pattern mining, the number of outliers, which were over 95% of the estimated trajectory, was significantly higher in AD than in NC (  = 0.002). The number of stay points, an index in which participants stayed in the same position for more than 2 s, was significantly higher in patients with AD and aMCI compared with NC (AD vs. NC:  = 0.003, aMCI vs. NC:  = 0.019). The HOT simulating real life showed potential as an ecologically valid test for assessing visuospatial memory function in daily life. Walking trajectory analysis suggested that patients with AD and aMCI wandered rather than going straight toward the hidden objects.

Recent improvements in neuroimaging and molecular markers of Alzheimer’s disease (AD) have aided diagnosis in the early stage of the disease, which greatly increases the chance for successful prevention and treatment. However, the expanding resources for AD diagnosis are unlikely to benefit all elderly due to economic burden. Here, we aimed to develop an inexpensive and sensitive method to detect early-stage AD. A scenario for real-world social event memory test (SEMT) was created and filmed in 360° video. Participants watched the 7-min video through head-mounted display (HMD) and then answered questionnaire about the video. We categorized the SEMT score into recall, recognition, and place-matching scores and compared them to scores on the Mini-Mental State Examination and Seoul Verbal Learning Test. Using the SEMT scores, we built a logistic regression model that discriminated between amyloid positivity and negativity of the participants, with a cross-validation AUC. Furthermore, a classifier was created using support vector machine, which produced 93.8–95.1% sensitivity in classifying individuals into four groups of normal, mild cognitive impairment with or without amyloid, and AD elderly. The high correlation between the SEMT score and amyloid positivity in individuals who experienced virtual social gathering through an HMD opens a new possibility for early diagnosis of AD.

Aims: Our purpose was to investigate differences in neuropsychological characteristics and glucose metabolism between early-onset mild cognitive impairment (EOMCI) and late onset MCI (LOMCI) patients and to determine if the baseline differences are predictive of conversion to dementia. Methods: We enrolled 28 patients with MCI (12 EOMCI, 16 LOMCI) and 2 age-matched control groups. At the end of a 5-year follow-up, we compared the baseline neuropsychological and PET data between converters and nonconverters. Results: The EOMCI patients obtained significantly higher scores in verbal recall and word fluency tests than the LOMCI patients. The EOMCI group, compared to the young controls, demonstrated hypometabolism in brain regions vulnerable in mild Alzheimer’s disease. Converters were significantly more impaired in the delayed verbal recall test than nonconverters (p = 0.028) and tended to be more impaired in the semantic word fluency test (p = 0.084). The baseline PET scan of the converters demonstrated severer hypometabolism in frontal areas than that of the nonconverters both in the EOMCI and LOMCI groups. Conclusion: Our study suggests that EOMCI patients may differ from LOMCI in the patterns of cognitive deficits and glucose hypometabolism. In addition, baseline neuropsychological and FDG-PET findings suggest that MCI patients with poor memory or frontal dysfunction are at greater risk of conversion to dementia.