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Abstract This study presents a novel analytical method for the quantitative and qualitative analysis of microplastics (MPs) in deionized (DI) water using Raman spectroscopy. Raman peak area ratios of 1295 cm−1 for polyethylene (PE) and 637 cm−1 for polyvinylchloride (PVC) to the broad H2O peak were utilized to establish a calibration model for the concentration of MPs dispersed in DI water at 0.1 wt% to 1.0 wt%. The calibration model demonstrated R2 values of 0.98537 for PE and 0.99511 for PVC, indicating high linearity between the peak area ratio and concentration. The calibration model was validated using mixed PE and PVC samples to confirm its applicability to real-world water bodies, where multiple types of MPs are present. The calculated standard error of calibration (SEC) and relative standard error of calibration (%RSEC) values further confirmed the accuracy of the predictions, providing a robust approach for detecting and quantifying MPs in aquatic environments.

We examined how controlling variables in a pre-metallization Ar sputter-etching process for in situ contact-hole cleaning affects the contact-hole profile, etching rate, and substrate damage. By adjusting process parameters, we confirmed that increasing plasma power lowered the DC bias but enhanced the etching rate of SiO2, while increasing RF power raised both, with RF power having a more pronounced effect. Higher Ar flow rate reduced etching uniformity and slightly lowered the DC bias. There was no significant difference in the amount of etching between the oxide film types, but the nitride/oxide selectivity ratio was about 1:2. Physical damage during Ar sputter-etching was closely linked to DC bias. finally, Finally, etching of the Si and CoSi2 sublayers was performed on the device contact hole model. At this time, Si losses of up to about 31.7 Å/s occurred, and the etch speed was strongly affected by the DC bias. By optimizing the RF power and plasma power, we achieved a Si/CoSi2 etch selectivity ratio of about 1:2.

This study explores the effects of different passivation gases on the properties of polymers formed on aluminum (Al) sidewalls during the etching process in Al-based interconnect structures. The research compares the use of nitrogen (N2) and ethylene diluted with helium (C2H4/He) as passivation gases, focusing on the resulting polymer’s composition, thickness, and strength, as well as the levels of residual chlorine post-etch. The findings reveal that using C2H4 leads to the formation of a thinner, weaker polymer with lower chlorine residue compared to the thicker, stronger polymer formed with N2. Elemental analysis further highlights significant differences in carbon and oxygen content, with C2H4-based polymers exhibiting lower carbon and higher oxygen levels. These results underscore the critical impact of passivation gas choice on the etching process and the integrity of Al-based interconnects, offering valuable insights for optimizing metal etching processes in semiconductor manufacturing.

Time-series data with missing values are a common occurrence in various fields, including healthcare, meteorology, and robotics. The process of imputation aims to fill in the missing values with valid values. Most imputation methods implicitly train models due to the presence of missing values. In this paper, we propose Random Drop Imputation with Self-training (RDIS), a novel training method for time-series data imputation models. In RDIS, we generate extra missing values by applying a random drop to the observed values in incomplete data. We can explicitly train the imputation models by filling in the missing values. Moreover, we utilize self-training with pseudo values to exploit the original missing values. To enhance the quality of pseudo values, we set a threshold and filter them based on entropy calculation. To evaluate the effectiveness of RDIS for imputing time-series data, we test it across several imputation models and obtain competitive results on three real-world datasets.

Objective : Cerebral endothelial cells have unique biological features and are fascinating candidate cells for stroke therapy. Methods : In order to understand the molecular mechanisms of human cerebral endothelial cell (hCMEC/D3) transplantation in a rat stroke model, we performed proteomic analysis using 2-dimensional electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Protein expression was confirmed by quantitative real-time PCR and Western blot. Results : Several protein spots were identified by gel electrophoresis in the sham, cerebral ischemia (CI), and CI with hCMEC/D3 treatment cerebral ischemia with cell transplantation (CT) groups, and we identified 14 differentially expressed proteins in the CT group. Proteins involved in mitochondrial dysfunction (paraplegin matrix AAA peptidase subunit, SPG7), neuroinflammation (peroxiredoxin 6, PRDX6), and neuronal death (zinc finger protein 90, ZFP90) were markedly reduced in the CT group compared with the CI group. The expression of chloride intracellular channel 4 proteins involved in post-ischemic vasculogenesis was significantly decreased in the CI group but comparable to sham in the CT group. Conclusion : These results contribute to our understanding of the early phase processes that follow cerebral endothelial cell treatment in CI. Moreover, some of the identified proteins may present promising new targets for stroke therapy. [ABSTRACT FROM AUTHOR]

Nanogenerators have garnered significant interest as environmentally friendly and potential energy-harvesting systems. Nanogenerators can be broadly classified into piezo-, tribo-, and hybrid nanogenerators. The hybrid nanogenerator used in this experiment is a nanogenerator that uses both piezo and tribo effects. These hybrid nanogenerators have the potential to be used in wearable electronics, health monitoring, IoT devices, and more. In addition, the versatility of the material application in electrospinning makes it an ideal complement to hybrid nanogenerators. However, despite their potential, several experimental variables, biocompatibility, and harvesting efficiency require improvement in the research field. In particular, maximizing the output voltage of the fibers is a significant challenge. Based on this premise, this study aims to characterize hybrid nanogenerators (HNGs) with varied structures and material combinations, with a focus on identifying HNGs that exhibit superior piezoelectric- and triboelectric-induced voltage. In this study, several HNGs based on coaxial structures were fabricated via electrospinning. PVDF-HFP and PAN, known for their remarkable electrospinning properties, were used as the primary materials. Six combinations of these two materials were fabricated and categorized into homo and hetero groups based on their composition. The output voltage of the hetero group surpassed that of the homo group, primarily because of the triboelectric-induced voltage. Specifically, the overall output voltage of the hetero group was higher. In addition, the combination group with the most favorable voltage characteristics combined PVDF-HFP@PAN(BTO) and PAN hollow, boasting an output voltage of approximately 3.5 V.

In this study, we analyze metal–insulator–metal (MIM) capacitors with different thicknesses of SixNy film (650 Å, 500 Å, and 400 Å) and varying levels of film quality to improve their capacitance density. SixNy thicknesses of 650 Å, 500 Å, and 400 Å are used with four different conditions, designated as MIM (N content 1.49), NEWMIM (N content 28.1), DAMANIT (N content 1.43), and NIT (N content 0.30). We divide the C–V characteristics into two categories: voltage coefficient of capacitance (VCC) and temperature coefficient of capacitance (TCC). There was an overall increase in the VCC as the thickness of the SixNy film decreased, with some variation depending on the condition. However, the TCC did not vary significantly with thickness, only with condition. At the same thickness, the NIT condition yielded the highest capacitance density, while the MIM condition showed the lowest capacitance density. This difference was due to the actual thickness of the film and the variation in its k-value depending on the condition. The most influential factor for capacitance uniformity was the thickness uniformity of the SixNy film.

The development of metal–insulator–semiconductor (MIS) capacitors requires device miniaturization and excellent electrical properties. Traditional SiO2 gate dielectrics have reached their physical limits. In this context, high-k materials such as TiO2 are emerging as promising alternatives to SiO2. However, the deposition of dielectric layers in MIS capacitors typically requires high-vacuum equipment and challenging processing conditions. Therefore, in this study, we present a new method to effectively fabricate a poly(vinylidene fluoride) (PVDF)-based TiO2 dielectric layer via electrospinning. Nano-microscale layers were formed via electrospinning by applying a high voltage to a polymer solution, and electrical properties were analyzed as a function of the TiO2 crystalline phase and residual amount of PVDF at different annealing temperatures. Improved electrical properties were observed with increasing TiO2 anatase content, and the residual amount of PVDF decreased with increasing annealing temperature. The sample annealed at 600 °C showed a lower leakage current than those annealed at 300 and 450 °C, with a leakage current density of 7.5 × 10−13 A/cm2 when Vg = 0 V. Thus, electrospinning-based coating is a cost-effective method to fabricate dielectric thin films. Further studies will show that it is flexible and dielectric tunable, thus contributing to improve the performance of next-generation electronic devices.

With the gradual miniaturization of electronic devices and the increasing interest in wearable devices, flexible microelectronics is being actively studied. Owing to the limitations of existing battery systems corresponding to miniaturization, there is a need for flexible alternative power sources. Accordingly, energy harvesting from surrounding environmental systems using fluorinated polymers with piezoelectric properties has received significant attention. Among them, polyvinylidene fluoride (PVDF) and PVDF co-polymers have been researched as representative organo-piezoelectric materials because of their excellent piezoelectric properties, mechanical flexibility, thermal stability, and light weight. Electrospinning is an effective method for fabricating nanofibrous meshes with superior surface-to-volume ratios from polymer solutions. During electrospinning, the polymer solution is subjected to mechanical stretching and in situ poling, corresponding to an external strong electric field. Consequently, the fraction of the piezoelectric β-phase in PVDF can be improved by the electrospinning process, and enhanced harvesting output can be realized. An overview of electrospun piezoelectric fibrous meshes composed of PVDF or PVDF co-polymers to be utilized is presented, and the recent progress in enhancement methods for harvesting output, such as fiber alignment, doping with various nanofillers, and coaxial fibers, is discussed. Additionally, other applications of these meshes as sensors are reviewed.