Association between T1w/T2w ratio in white matter and cognitive function in Alzheimer's disease.

Loss of myelin in the brain may lead to cognitive decline in Alzheimer's disease (AD). The ratio of T1 weighted/T2 weighted (T1w/T2w) on magnetic resonance imaging has been used as a proxy for myelin content in the brain. Using this approach, we investigated the correlation between the white matter (WM) T1w/T2w ratio and both cognitive scores and disease progression in AD. A total of 93 participants who were cognitively unimpaired or diagnosed with mild cognitive impairment or AD dementia were recruited between March 2021 and November 2022. All participants were assessed using neuropsychological tests, and a subset of the participants was assessed every 1 year to monitor disease progression. We observed significant positive associations between the WM T1w/T2w ratio and executive function within the fornix, sagittal stratum, anterior internal capsule, and body of the corpus callosum (False discovery rate [FDR]-corrected P-value < 0.05). There was a marginal interaction between the WM T1w/T2w ratio of the left anterior internal capsule and the longitudinal change in sum of boxes of the Clinical Dementia Rating Scale (FDR-corrected P-value = 0.05). The present study demonstrated that the WM T1w/T2w ratio was associated with executive function and disease progression, suggesting that it may be a novel neuroimaging marker for AD.

Time Perception and Memory in Mild Cognitive Impairment and Alzheimer's Disease: A Preliminary Study.

Background and Purpose: Episodic memory is a system that receives and stores information about temporally dated episodes and their interrelations. Our study aimed to investigate the relevance of episodic memory to time perception, with a specific focus on simultaneity/order judgment. Methods: Experiment 1 employed the simultaneity judgment task to discern differences in time perception between patients with mild cognitive impairment or dementia, and age-matched normals. A mathematical analysis capable of estimating subjects' time processing was utilized to identify the sensory and decisional components of temporal order and simultaneity judgment. Experiment 2 examined how differences in temporal perception relate to performance in temporal order memory, in which time delays play a critical role. Results: The temporal decision windows for both temporal order and simultaneity judgments exhibited marginal differences between patients with episodic memory impairment, and their healthy counterparts (p = 0.15, t(22) = 1.34). These temporal decision windows may be linked to the temporal separation of events in episodic memory (Pearson's ρ = -0.53, p = 0.05). Conclusions: Based on our findings, the frequency of visual events accumulated and encoded in the working memory system in the patients' and normal group appears to be approximately (5.7 and 11.2) Hz, respectively. According to the internal clock model, a lower frequency of event pulses tends to result in underestimation of event duration, which phenomenon might be linked to the observed time distortions in patients with dementia.

A novel statistical-dynamical method for a seasonal forecast of particular matter in South Korea.

Societal concerns about air quality in East Asia are still growing despite country-level efforts to reduce air pollution emissions. In coping with this growing concern, the government and the public demand a longer­lead forecast of air quality to ensure sufficient response time until society prepares for countermeasures such as a temporary reduction of specific emission sources. Here we propose a novel method that produces skillful seasonal forecasting of wintertime (December to February) PM10 concentration over South Korea. The method is based on the idea that climate condition and air quality have co-variability in the seasonal time scales and that the state-of-art seasonal prediction model will benefit air quality forecasting. More specifically, a linear regression model is constructed to link observed winter PM10 concentration and climate variables where the predicted climate variables were furnished from NCEP CFSv2 forecast initialized during autumn. In this case, climate variables were selected as predictors of the model because they are not only physically related to air quality but also 'predictable' in CFS hindcast. Through analysis of retrospective forecasts of 20 winters for the period 2001-2020, we found this model shows statistically significant skill for the seasonal forecast of wintertime PM10 concentration.

Wavelength-Tunable and Water-Stable Cesium-Lead-Based All-Bromide Nanocrystal-Polymer Composite Films Using Ultraviolet-Curable Prepolymer as an Anti-Solvent.

All-inorganic metal halide perovskite nanocrystals (IPeNCs) have become one of the most promising luminescent materials for next-generation display and lighting technology owing to their excellent color expression ability. However, research on IPeNCs with stable blue emission is limited. In this paper, we report stable blue emissive all-bromide IPeNCs obtained through a modified ligand-assisted reprecipitation method using an ultraviolet (UV)-curable prepolymer as the anti-solvent at a low temperature. We found that the blue emission originates from quantum-confined CsPbBr3 nanoparticles formed together with the colorless wide-bandgap Cs4PbBr6 nanocrystals. When the temperature of the prepolymer was increased from 0 to 50 °C, CsPbBr3 nanoparticles became larger and more crystalline, thereby altering their emission color from blue to green. The synthesized all-bromide blue-emitting IPeNC solution remained stable for over 1 h. It also remained stable when it was mixed with the green-emitting IPeNC solution. By simply exposing the as-synthesized IPeNC-prepolymer solutions to UV light, we formed water-stable composite films that emitted red, green, blue, and white colors. We believe that this synthetic method can be used to develop color-emitting composite materials that are highly suitable for application as the color conversion films of full-color liquid crystal display backlight systems and lighting applications.

A curtailed task for quantitative evaluation of visuomotor adaptation in the head-mounted display virtual reality environment.

To accurately perform a goal-directed movement in continuously changing environments, it is unavoidable for individuals to adapt accordingly. The cerebellum has been known to be responsible for such process, specifically adaptation using sensorimotor information. As shown in previous studies, using HMD-VR technology in an experimental setting has similar advantages as in the real-world environment: researchers can manipulate the experimental environment, precisely control the experiments, and quantitatively analyze errors in real time. Moreover, the HMD-VR environment provides high immersiveness and embodiment which even enhance motor learning and increase engagement and motivation of individuals more than real-world environments do. In our HMD-VR-based task, the subjects were trained to adapt to a condition in which the visual information was artificially 20°clockwise rotated from the actual cursor movement. The subjects used a virtual reality tracker to move the cursor from a starting point to a target that appeared randomly at five locations, 20 cm from the starting point with an interval of 15°. Although no significant side effects were expected from experiencing the HMD-VR environment, we considered the appropriate number of trials for patients with cerebellar disease for future use in clinical settings. To examine the feasibility of our task for analysis of visuomotor adaptation pattern as shown in a real-world-based task, we created and compared two paradigms with a difference in the number of trials. As we expected, the results showed that the heading angle error decreased as the participants of both paradigms continued the task and that there was no significant difference between the two paradigms. Next, we applied our short task paradigm to patients diagnosed with cerebellar ataxia and age-matched controls for further examination of applicability to diagnosis and rehabilitation of the patients. As a result, we observed the distinguishable adaptation pattern of the patient group by using our paradigm. Overall, the results suggest that our paradigm is feasible to analyze the visuomotor adaptation pattern of healthy individuals and patients with cerebellar ataxia so may contribute to the clinical field.

Enhanced Light Absorption by Facile Patterning of Nano-Grating on Mesoporous TiO2 Photoelectrode for Cesium Lead Halide Perovskite Solar Cells.

CsPbIBr2, a cesium-based all-inorganic halide perovskite (CsPe), is a very promising alternative material to mainstream organic-inorganic hybrid halide perovskite (HPe) materials owing to its exceptional moisture stability, thermal stability, and light stability. However, because of the wide band gap (2.05 eV) of CsPbIBr2, it has a low power conversion efficiency (PCE), which hinders its application in highly efficient solar cells. In this study, a facile nanoimprinted one-dimensional grating nanopattern (1D GNP) formation on mesoporous TiO2 (mp-TiO2) photoelectrodes was introduced to improve the effective light utilization and enhance the performance of CsPbIBr2 perovskite solar cells (PSCs). The 1D GNP structure on the mp-TiO2 layer increases the light absorption efficiency by diffracting the unabsorbed light into the active mp-TiO2 and CsPbIBr2 layers as well as increasing the charge separation and collection due to the extended interfacial contact area between the mp-TiO2 and CsPbIBr2 layers. Consequently, both the current density (JSC) and the fill factor (FF) of the fabricated cells improved, leading to over a 20% enhancement in the solar cell's PCE. Thus, this periodic grating structure, fabricated by simple nanoimprinting, could play an important role in the large-scale production of highly efficient and cost-effective Cs-based PSCs.

Efficient TiO2 Surface Treatment Using Cs2CO3 for Solution-Processed Planar-Type Sb2S3 Solar Cells.

We report a highly effective surface treatment method for planar-type Sb2S3 solar cells by employing a Cs2CO3-modified compact TiO2 (c-TiO2) electron transport layer. It is found that surface treatment using a Cs2CO3 solution can shift the work function of c-TiO2 upward and reduce its surface roughness. As a result, compared with the power conversion efficiency of untreated solar cells, that of the treated solar cells with a glass/FTO/c-TiO2(/Cs2CO3)/Sb2S3/P3HT/Au structure significantly improved from 2.83 to 3.97%. This study demonstrates that the introduction of Cs2CO3 on a c-TiO2 layer is a simple and efficient way to adjust the work function of the electron transport layer and fabricate high-performance planar-type Sb2S3 solar cells.

Fabrication of Sb2S3 Hybrid Solar Cells Based on Embedded Photoelectrodes of Ag Nanowires-Au Nanoparticles Composite.

The Ag nanowire (NW) + Au nanoparticle (NP)-embedded TiO2 photoelectrodes were adopted for conventional planar TiO2-based Sb2S3 hybrid solar cells to improve the cell efficiency. Compared to conventional planar TiO2-based Sb2S3 hybrid solar cells, the Ag NW + Au NP/TiO2-based Sb2S3 hybrid solar cells exhibited an improvement of approximately 40% in the cell efficiency due to the significant increase in both Jsc and Voc. These enhanced Jsc and Voc were attributed to the increased surface area, charge-collection efficiency, and light absorption by embedding the Ag NWs + Au NPs composite. The Ag NW + Au NP/TiO2-based Sb2S3 hybrid solar cells showed the highest efficiency of 2.17%, demonstrating that the Ag NW + Au NP-embedded TiO2 photoelectrode was a suitable photoelectrode structure to improve the power conversion efficiency in the Sb2S3 hybrid solar cells.

[18F]-THK5351 PET Imaging in Patients With Semantic Variant Primary Progressive Aphasia.

BACKGROUND: Semantic variant primary progressive aphasia (svPPA) has been associated with a variety of proteinopathies, mainly transactive response DNA-binding protein, but also with tau and ß-amyloid. Recently selective tau tracers for positron emission tomography (PET) have been developed to determine the presence of cerebral tau deposits in vivo. Here, we investigated the topographical distribution of THK5351 in svPPA patients. MATERIALS AND METHODS: Five svPPA patients, 14 Alzheimer's disease patients, and 15 age-matched normal controls underwent [F]-THK5351 PET scans, magnetic resonance imaging, and detailed neuropsychological tests. [F]-fluorodeoxyglucose PET was obtained in 3 svPPA patients, whereas the remaining 2 underwent amyloid PET using [F]-flutemetamol. Tau distribution among the 3 groups was compared using regions of interest-based and voxel-based statistical analyses. RESULTS: In svPPA patients, [F]-THK5351 retention was elevated in the anteroinferior and lateral temporal cortices compared with the normal controls group (left>right), and in the left inferior and temporal polar region compared with Alzheimer's disease patients. [F]-THK5351 retention inversely correlated with glucose metabolism, whereas regional THK retention correlated with clinical severity. [F]-flutemetamol scans were negative for ß-amyloid. CONCLUSIONS: These findings show that [F]-THK5351 retention may be detected in cortical regions correlating with svPPA pathology.

Tau positron emission tomography using [18F]THK5351 and cerebral glucose hypometabolism in Alzheimer's disease.

This study aims to evaluate the clinical validity of [18F]THK5351 positron emission tomography (PET) for the assessment of disease progression and symptoms in Alzheimer's disease (AD). Fifty-one patients with AD dementia, 30 patients with amnestic mild cognitive impairment (aMCI), and 43 controls with normal cognition (NC) were included. All subjects underwent [18F]THK5351 PET, 3.0-T magnetic resonance imaging, and detailed neuropsychological tests. Regions of interest and voxel-based statistical analyses were performed. In patients with AD dementia, [18F]THK5351 retention was greater in most association cortices as well as the limbic area compared to NC or aMCI participants. Patients with aMCI also showed higher THK5351 retention in those areas compared to NC. [18F]THK5351 retention significantly correlated with neuropsychological test results. Negative correlations between [18F]THK5351 and [18F] fluorodeoxyglucose were observed in AD dementia and aMCI groups. Mirror images of [18F]THK5351 retention and glucose hypometabolism in [18F] fluorodeoxyglucose were noticeable in the focal variants of AD. [18F]THK5351 PET reflects disease severity and symptoms in AD. Our results suggest [18F]THK5351 is reflective of tau-related AD pathology.

Stroke outcomes are worse with larger leukoaraiosis volumes.

Leukoaraiosis or white matter hyperintensities are frequently observed on magnetic resonance imaging of stroke patients. We investigated how white matter hyperintensity volumes affect stroke outcomes, generally and by subtype. In total, 5035 acute ischaemic stroke patients were enrolled. Strokes were classified as large artery atherosclerosis, small vessel occlusion, or cardioembolism. White matter hyperintensity volumes were stratified into quintiles. Mean age (± standard deviation) was 66.3 ± 12.8, 59.6% male. Median (interquartile range) modified Rankin Scale score was 2 (1-3) at discharge and 1 (0-3) at 3 months; 16.5% experienced early neurological deterioration, and 3.3% recurrent stroke. The Cochran-Mantel-Haenszel test with adjustment for age, stroke severity, sex, and thrombolysis status showed that the distributions of 3-month modified Rankin Scale scores differed across white matter hyperintensity quintiles (P < 0.001). Multiple ordinal logistic regression analysis showed that higher white matter hyperintensity quintiles were independently associated with worse 3-month modified Rankin Scale scores; adjusted odds ratios (95% confidence interval) for the second to fifth quintiles versus the first quintile were 1.29 (1.10-1.52), 1.40 (1.18-1.66), 1.69 (1.42-2.02) and 2.03 (1.69-2.43), respectively. For large artery atherosclerosis (39.0%), outcomes varied by white matter hyperintensity volume (P = 0.01, Cochran-Mantel-Haenszel test), and the upper three white matter hyperintensity quintiles (versus the first quintile) had worse 3-month modified Rankin Scale scores; adjusted odds ratios were 1.45 (1.10-1.90), 1.86 (1.41-2.47), and 1.89 (1.41-2.54), respectively. Patients with large artery atherosclerosis were vulnerable to early neurological deterioration (19.4%), and the top two white matter hyperintensity quintiles were more vulnerable still: 23.5% and 22.3%. Moreover, higher white matter hyperintensities were associated with poor modified Rankin Scale improvement: adjusted odds ratios for the upper two quintiles versus the first quintile were 0.66 (0.47-0.94) and 0.62 (0.43-0.89), respectively. For small vessel occlusion (17.8%), outcomes tended to vary by white matter hyperintensitiy volume (P = 0.10, Cochran-Mantel-Haenszel test), and the highest quintile was associated with worse 3-month modified Rankin Scale scores: adjusted odds ratio for the fifth quintile versus first quintile, 1.98 (1.23-3.18). In this subtype, worse white matter hyperintensities were associated with worse National Institute of Health Stroke Scale scores at presentation. For cardioembolism (20.6%), outcomes did not vary significantly by white matter hyperintensity volume (P = 0.19, Cochran-Mantel-Haenszel test); however, the adjusted odds ratio for the highest versus lowest quintiles was 1.62 (1.09-2.40). Regardless of stroke subtype, white matter hyperintensities were not associated with stroke recurrence within 3 months of follow-up. In conclusion, white matter hyperintensity volume independently correlates with stroke outcomes in acute ischaemic stroke. There are some suggestions that stroke outcomes may be affected by leukoaraiosis differentially depending on stroke subtypes, to be confirmed in future investigations.

Inverted polymer fullerene solar cells exceeding 10% efficiency with poly(2-ethyl-2-oxazoline) nanodots on electron-collecting buffer layers.

Polymer solar cells have been spotlighted due to their potential for low-cost manufacturing but their efficiency is still less than required for commercial application as lightweight/flexible modules. Forming a dipole layer at the electron-collecting interface has been suggested as one of the more attractive approaches for efficiency enhancement. However, only a few dipole layer material types have been reported so far, including only one non-ionic (charge neutral) polymer. Here we show that a further neutral polymer, namely poly(2-ethyl-2-oxazoline) (PEOz) can be successfully used as a dipole layer. Inclusion of a PEOz layer, in particular with a nanodot morphology, increases the effective work function at the electron-collecting interface within inverted solar cells and thermal annealing of PEOz layer leads to a state-of-the-art 10.74% efficiency for single-stack bulk heterojunction blend structures comprising poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxylate] as donor and [6,6]-phenyl-C71-butyric acid methyl ester as acceptor.

Pronounced Cosolvent Effects in Polymer:Polymer Bulk Heterojunction Solar Cells with Sulfur-Rich Electron-Donating and Imide-Containing Electron-Accepting Polymers.

The performance of solar cells with a polymer:polymer bulk heterojunction (BHJ) structure, consisting of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxylate] (PTB7-Th) donor and poly[[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)] (P(NDI2OD-T2)) acceptor polymers, was investigated as a function of cosolvent (p-xylene:chlorobenzene (pXL:CB)) composition ratio. A remarkable efficiency improvement (∼38%) was achieved by spin-coating the photoactive blend layer from pXL:CB = 80:20 (volume) rather than pXL alone, but the efficiency then decreased when the CB content increased further to pXL:CB = 60:40. The improved efficiency was correlated with a particular PTB7-Th:P(NDI2OD-T2) donor-acceptor blend nanostructure, evidenced by a fiber-like surface morphology, a red-shifted optical absorption, and enhanced PL quenching. Further device optimization for pXL:CB = 80:20 films yielded a power conversion efficiency of ∼5.4%. However, these devices showed very poor stability (∼15 min for a 50% reduction in initial efficiency), owing specifically to degradation of the PTB7-Th donor-component. Replacing PTB7-Th with a more stable donor polymer will be essential for any application potential to be realized.

Grading and interpretation of white matter hyperintensities using statistical maps.

BACKGROUND AND PURPOSE: We aimed to generate rigorous graphical and statistical reference data based on volumetric measurements for assessing the relative severity of white matter hyperintensities (WMHs) in patients with stroke. METHODS: We prospectively mapped WMHs from 2699 patients with first-ever ischemic stroke (mean age=66.8±13.0 years) enrolled consecutively from 11 nationwide stroke centers, from patient (fluid-attenuated-inversion-recovery) MRIs onto a standard brain template set. Using multivariable analyses, we assessed the impact of major (age/hypertension) and minor risk factors on WMH variability. RESULTS: We have produced a large reference data library showing the location and quantity of WMHs as topographical frequency-volume maps. This easy-to-use graphical reference data set allows the quantitative estimation of the severity of WMH as a percentile rank score. For all patients (median age=69 years), multivariable analysis showed that age, hypertension, atrial fibrillation, and left ventricular hypertrophy were independently associated with increasing WMH (0-9.4%, median=0.6%, of the measured brain volume). For younger (≤69) hypertensives (n=819), age and left ventricular hypertrophy were positively associated with WMH. For older (≥70) hypertensives (n=944), age and cholesterol had positive relationships with WMH, whereas diabetes mellitus, hyperlipidemia, and atrial fibrillation had negative relationships with WMH. For younger nonhypertensives (n=578), age and diabetes mellitus were positively related to WMH. For older nonhypertensives (n=328), only age was positively associated with WMH. CONCLUSIONS: We have generated a novel graphical WMH grading (Kim statistical WMH scoring) system, correlated to risk factors and adjusted for age/hypertension. Further studies are required to confirm whether the combined data set allows grading of WMH burden in individual patients and a tailored patient-specific interpretation in ischemic stroke-related clinical practice.

Enhanced performance of polymer solar cells with a fluorocyanophenyl compound as an additive.

The efficiency of polymer solar cells (PSCs) with P3HT [poly(3-hexyl thiophene)]:PC61BM [[6,6]-phenyl C61-butyric acid methyl ester] blend film was improved by the incorporation of a fluorocyanophenyl compound, 3,4,5,6-tetrafluorophthalonitrile (TFP), as an additive. When the amount of TFTadditive was 5 wt% based on the total amount of P3HT and PC61BM, the highest efficiency was achieved. The annealed PSC with 5 wt% TFP had a power conversion efficiency of 4.45% compared with that (3.57%) of the reference cell without the additive, which corresponds to an increase of about 18.7% in the efficiency due to an enhancement in the short circuit current (J(sc)). A seriese of measurements such as UV-visible absorption spectroscopy, X-ray measurements, atomic force microscopic images and incident photon to current conversion efficiency (IPCE) spectra revealed that the increased J(sc) in the PSC with P3HT:PC61BM:TFP blend film was due to an improvement in both exciton generation and charge transport efficiency, resulting from higher absorbance, larger crystal size and more effective phase separation.

Improved photovoltaic properties of polymer solar cells with a phenyl compound as an additive.

A phenyl compound with electron withdrawing substituents, 3-fluoro-4-cyanophenol (FCP), was used as an additive in polymer solar cells with a P3HT [poly(3-hexyl thiophene)]:PCBM [[6,6]-phenyl-C61-butyric acid methyl ester] blend film. Under simulated solar illumination of AM 1.5 (100 mW/cm2), the devices fabricated using a P3HT:PCBM (1:0.9 w:w) layer blended with 5 wt% of FCP achieved an enhanced power conversion efficiency (PCE) of 4.8% due to the improved short circuit current and fill factor, as compared to reference cells with PCE = 4.1%. UV-visible absorption spectra, X-ray measurements and carrier mobility studies revealed that FCP facilitated the ordering of the P3HT chains, resulting in higher absorbance, larger crystal size, closer packing and enhanced hole mobility.

Efficient inverted bulk-heterojunction polymer solar cells with self-assembled monolayer modified zinc oxide.

The performance of poly(3-hexylthiophen) (P3HT) and [6, 6]phenyl C61 butyric acid methyl ester ([60]PCBM)-based inverted bulk-heterojunction (BHJ) polymer solar cells (PSCs) is enhanced by the modification of zinc oxide (ZnO)/BHJ interface with carboxylic-acid-functionalized self-assembled monolayers (SAMs). Under simulated solar illumination of AM 1.5 (100 mW/cm2), the inverted devices fabricated with SAM-modified ZnO achieved an enhanced power conversion efficiency (PCE) of 3.34% due to the increased fill factor and photocurrent density as compared to unmodified cells with PCE of 2.60%. This result provides an efficient method for interface engineering in inverted BHJ PSCs.

Influence of nickel(II) oxide nanoparticle addition on the performance of organic field effect transistors.

Here, the improved performance of organic field effect transistors (OFET) by doping inorganic nanoparticles into a semiconducting polymer as a channel layer is briefly reported. Nickel(II) oxide nanoparticle (NiOnp) was used as an inorganic dopant while regioregular poly(3-hexylthiophene) (P3HT) was used as a matrix polymer for the channel layer in the OFETs. The doping ratio of NiOnp was made 1 wt.% so that it would minimally influence the nanostructure of the P3HT channel layer. The results showed that the optical absorption spectrum of the P3HT film was slightly red-shifted by the NiOnp doping, which reflects the improved crystallinity of the P3HT domains in the P3HT:NiOnp films. The drain current of the OFETs with the P3HT:NiOnp films was significantly enhanced ca. three-to-seven fold by the NiOnp doping under appying gate voltages while the hole mobility of the OFETs P3HT:NiOnp films was improved as much as three fold by the NiOnp doping. The enhanced performance has been assigned to the role of NiOnp that has relatively higher hole mobility than the P3HT polymer.