1,721,654 research outputs found
Fabrication and characterization of spin self-assembled PPV/montmorillonite multilayer thin films
No full textMultilayer nanostructural thin films through a layer-by-layer spin self-assembly method were prepared using poly (p-phenylene vinylene)/montmorillonite. Sodium montmorillonite particles exfoliated into single sheets and cationic PPV precursor and such anionic MMT plates were spin self-assembled by electrostatic attraction. Self-assembled MMT layers blocked the penetration of oxygen and moisture and they reduced the photo-oxidation of the emitting material. Spin self-assembled films showed higher environmental stability and luminescence, and their PL spectra were somewhat different from that of bulk PPV films
Development of a micro-thermal flow sensor with thin-film thermocouples
No full textA micro-thermal flow sensor is developed using thin-film thermocouples as temperature sensors. A micro-thermal flow sensor consists of a heater and thin-film thermocouples which are deposited on a quartz wafer using stainless steel masks. Thin-film thermocouples are made of standard K-type thermocouple materials. The mass flow rate is measured by detecting the temperature difference of the thin-film thermocouples located in the upstream and downstream sections relative to a heater. The performance of the micro-thermal flow sensor is experimentally evaluated. In addition, a numerical model is presented and verified by experimental results. The effects of mass flow rate, input power, and position of temperature sensors on the performance of the micro-thermal flow sensor are experimentally investigated. At low values, the mass flow rate varies linearly with the temperature difference. The linearity of the micro-thermal flow sensor is shown to be independent of the input power. Finally, the position of the temperature sensors is shown to affect both the sensitivity and the linearity of the micro-thermal flow sensor.This work was supported by the Korea Science & Engineering
Foundation through the NRL Program (grant 2006-02147)
Diffusion-weighted imaging of breast invasive lobular carcinoma: Comparison with invasive carcinoma of no special type using a histogram analysis
Full text linkBACKGROUND: To investigate the imaging findings and visibility of breast invasive lobular carcinoma (ILC) on diffusion-weighted imaging (DWI) and compare quantitative apparent diffusion coefficient (ADC) metrics of ILC and invasive carcinoma of no special type (NST) using a histogram analysis. METHODS: We performed an observational retrospective study of 629 consecutive women with pathologically proven ILC and invasive ductal carcinoma of NST, who underwent 3-T MRI including DWI, between January 2017 and August 2020. RESULTS: After propensity score matching, 71 women were allocated to each group. On DWI, 9 (12.7%) lesions of ILC and 4 (5.6%) invasive carcinomas of the NST were not visualized. For the tumor visibility on DWI, tumor size, tumor ADC value, and background diffusion grade were significantly associated with the visibility score in both groups (all P<0.05), whereas the mean background ADC value was not significant (P>0.05). The mean ADC (1.226x10(-3) vs. 1.052x10(-3) mm(2)/s, P<0.001), median ADC (1.222x10(-3) vs. 1.051x10(-3) mm(2)/s, P=0.002), maximum ADC (1.758x10(-3) vs. 1.504x10(-3) mm(2)/s, P<0.001), minimum ADC (0.717x10(-3) vs. 0.649x10(-3) mm(2)/s, P=0.003), 90th percentile ADC (1.506x10(-3) vs. 1.292x10(-3) mm(2)/s, P<0.001) and 10th percentile ADC (0.956x10(-3) vs. 0.818x10(-3) mm(2)/s, P=0.008) were higher in ILC than in invasive carcinoma of NST. Additionally, the ADC difference value of the ILC was higher than that of invasive carcinoma of NST (1.04x10(-3) vs. 0.855x10(-3) mm(2)/s, P=0.027). CONCLUSIONS: On DWI, the visibility of ILC was lower compared to invasive carcinoma of NST. ILC showed higher quantitative ADC values and higher ADC difference values
Fabrication and Characterization of Spin Self-assembled PPV/Montmorillonite Multilayer Films
No full textMultilayer nanostructural thin films through a layer-by-layer spin self-assembly method were prepared using poly(p-phenylene vinylene)/montmorillonite. Sodium montmorillonite particles exfoliated into single sheets and cationic PPV precursor and such anionic MMT plates were spin self-assembled by electrostatic attraction. Self-assembled MMT layers blocked the penetration of oxygen and moisture and they reduced the photo-oxidation of the emitting material. Spin self-assembled films showed higher environmental stability and luminescence, and their PL spectra were somewhat different from that of bulk PPV films
Visualization of the inverse layer-plus-island growth in Fe islands on W(110) substrate
No full textMany experiments have been conducted so far to control the growth mode in heterostructures, but success has only been restricted to strain-controlled growth systems. In this study, using the shadow mask deposition technique, we have changed the growth mode in the Fe/W heterostructures from the layer-plus-island growth mode to island-plus-layer growth mode. From this, we have ignited the competing growth between forming the islands and wetting the first layer, and have directly visualized the island-plus-layer growth by controlling the annealing temperature of the system. This unconventional growth mode may play an important role in studying the hidden boundaries of hetero-interfaces. (C) 2015 Elsevier B.V. All rights reserved.1112sciescopuskc
Comment on "Atomic Structure, Energetics, and Dynamics of Topological Solitons in Indium Chains on Si(111) Surfaces
No full textopen1122sciescopu
Topological Solitons versus Nonsolitonic Phase Defects in a Quasi-One-Dimensional Charge-Density Wave
Full text linkWe investigated phase defects in a quasi-one-dimensional commensurate charge-density wave (CDW) system, an In atomic wire array on Si(111), using low temperature scanning tunneling microscopy. The unique fourfold degeneracy of the CDW state leads to various phase defects, among which intrinsic solitons are clearly distinguished. The solitons exhibit a characteristic variation of the CDW amplitude with a coherence length of about 4 nm, as expected from the electronic structure, and a localized electronic state within the CDW gap. While most of the observed solitons are trapped by extrinsic defects, moving solitons are also identified and their novel interaction with extrinsic defects is disclosed. DOI: 10.1103/PhysRevLett.109.246802X1115sciescopu
Deep learning model for the diagnosis of breast cancers smaller than 1 cm with ultrasonography: integration of ultrasonography and clinical factors
No full textBackground: The aim of this study was to evaluate the diagnostic performance of a deep learning (DL) algorithm for breast masses smaller than 1 cm on ultrasonography (US). We also evaluated a hybrid model that combines the predictions of the DL algorithm from US images and a patient’s clinical factors including age, family history of breast cancer, BRCA mutation, and mammographic breast density. Methods: A total of 1,041 US images (including 633 benign and 408 malignant masses) were obtained from 1,041 patients who underwent US between January 2014 and June 2021. All US images were randomly divided into training (513 benign and 288 malignant lesions), validation (60 benign and 60 malignant lesions), and test (60 benign and 60 malignant lesions) data sets. A mask region-based convolutional neural network (R-CNN) was used to generate a feature map of the input image with a CNN and a pre-trained ResNet101 structure. For the clinical model, the multilayer perceptron (MLP) structure was used to calculate the likelihood that the tumor was benign or malignant from the clinical risk factors. We compared the diagnostic performance of an image-based DL algorithm, a combined model with regression, and a combined model with the decision tree method. Results: Using the US images, the area under the receiver operating characteristics curve (AUROC) of the DL algorithm was 0.85 [95% confidence interval (CI), 0.78–0.92]. With the combined model using a regression model, the sensitivity was 78.3% (95% CI, 67.9–88.8%) and the specificity was 85% (95% CI, 76–94%). The sensitivity of the combined model using a regression model was significantly higher than that of the imaging model (P=0.003). The specificity values of the two models were not significantly different (P=0.083). The sensitivity and specificity of the combined model using a decision tree model were 75% (95% CI, 62.1–85.3%) and 91.7% (95% CI, 81.6–97.2%), respectively. The sensitivity of the combined model using the decision tree model was higher than that of the image model but the difference was not statistically significant (P=0.081). The specificity values of the two models were not significantly different (P=0.748). Conclusions: The DL model could feasibly be used to predict breast cancers smaller than 1 cm. The combined model using clinical factors outperformed the standalone US-based DL model
A Receptor-mediated Gene Delivery System Using Streptavidin and Biotin-derivatized, Pegylated Epidermal Growth Factor
No full textAn efficient receptor-mediated non-viral gene delivery formulation based on mono-pegylated recombinant human epidermal growth factor (EGF) was developed using a streptavidin-biotin system. Biotin-derivatized and mono-pegylated EGF was prepared by conjugating a biotin-PEG-NHS derivative to EGF and purified through a chromatographic method. Luciferase plasmid DNA and polyethylenimine (PEI) were complexed to form positively charged nanoparticles on which negatively charged streptavidin was first coated and then biotin-PEG-EGF conjugate was immobilized via streptavidin-biotin interaction. The EGF-PEG-biotin-streptavidin-PEI-DNA complexes were characterized in terms of their effective diameter and surface zeta (zeta)-potential value under various formulation conditions. The formulated complexes exhibited high transfection efficiency (similar to10(8) in luciferase activity) with no inter-particle aggregation. This was attributed to enhanced cellular uptake of the resultant complexes via receptor-mediated endocytosis. Furthermore, in the presence of serum proteins, a slight decrease in transfection efficiency was observed due to the presence of PEG chains on the surface. (C) 2002 Elsevier Science B.V. All rights reserved.the Ministry of Health and Welfare, South Kore
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