Study on fabrication of nanofibers with multifunctions for textile, water filtration, and biomedicine (濾過および生物医学の為の多機能ナノファイバー製造に関する研究)

信州大学(Shinshu university)博士（工学）ThesisPHAN DUY NAM. Study on fabrication of nanofibers with multifunctions for textile, water filtration, and biomedicine　(濾過および生物医学の為の多機能ナノファイバー製造に関する研究)【要旨】. 信州大学, 2020, 博士論文. 博士（工学）, 甲第724号, 令和02年03月20日授与.doctoral thesi

Composite Nanofibers: Recent Progress in Adsorptive Removal and Photocatalytic Degradation of Dyes

This chapter intends to review the state of the art of a new nanomaterial generation based on electrospun composite nanofibers for dye removal from wastewater. Natural polymer-based nanofibers, nanofibers with unique morphology, and carbon nanofibers were comprehensively reviewed as capable carriers for a broad spectrum of functional materials such as metal oxides, zeolite, graphene and graphene oxide (GO), and metal-organic frameworks (MOFs) in the application of dye removal. The various nanostructures, adsorption capacity, advantages, and drawbacks were discussed along with mechanistic actions in the adsorption process and photocatalytic performance that emphasize current research development, opportunities, and challenges. The chapter covers multiple intriguing topics with in-depth discussion and is a valuable reference for researchers who are working on nanomaterials and the treatment of colored waters

Performance of cluster-based cognitive multihop networks under joint impact of hardware noises and non-identical primary co-channel interference

In this paper, we evaluate outage probability (OP) of a cluster-based multi-hop protocol operating on an underlay cognitive radio (CR) mode. The primary network consists of multiple independent transmit/receive pairs, and the primary transmitters seriously cause co-channel interference (CCI) to the secondary receivers. To improve the outage performance for the secondary network under the joint impact of the CCI and hardware imperfection, we employ the best relay selection at each hop. Moreover, the destination is equipped with multiple antennas and uses the selection combining (SC) technique to enhance the reliability of the data transmission at the last hop. For performance evaluation, we first derive an exact formula of OP for the primary network which is used to calculate the transmit power of the secondary transmitters. Next, an exact closed-form expression of the end-to-end OP for the secondary network is derived over Rayleigh fading channels. We then perform Monte-Carlo simulations to validate the derivations. The results present that the CCI caused by the primary operations significantly impacts on the outage performance of the secondary network

Application of Nanowires for Retinal Regeneration

Nanowires aim at developing advanced architectures are gaining popularity for damaged neural systems. The retina with a complicated structure is an essential part of our visual nervous system. Any disorder inside retina could lead to blindness due to irregularity in transferring neural signals to the brain. In recent years, the emergence of nanostructures, as well as nanowires, has provided a viable means for enhancing the regeneration of retinal. Nanowires with the ability to sense light and converting it to the electrical signals simulate the extracellular electrical properties, which are the newest nanostructures for the retinal applications. The different structure of nanowires has been examined in vitro, and several others are undergoing in vivo for vision recovery. Among the structures, core-shell nanowires and functionalized nanowires with gold nanoparticles attract the attention for the regeneration of retinal neural systems. Herein, subsequently provide an introduction to the anatomy of the retina, and retinal disorders, the latest progress in the regeneration of retina and vision using nanowires will be reviewed. Also, the different structures, including core-shell and functionalized nanowires with nanoparticles, will be examined. Eventually, the point of view and perspective of applying nanowire in retinal regeneration will be offered

STATE PROBLEM OF BALANCING SEWING LINE OF INDUSTRIAL KNITTED PRODUCTS

Line balancing is always a big problem appearing in industrial production. Manual balancing of industrial sewing products takes a long time to give results, which depends on the experience of the sewing line manager, moreover, the efficiency is not necessarily optimal. Digital conversion will help find a solution to balance the sewing line more quickly, accurately, and optimally. This study presents the statements of the problem of balancing knitted garment lines in the industry with the line balancing process according to the method of Hanoi University of Science and Technology (HUST) and BSL-HUST-1 software, which is the software designed and built by our research group. For the balancing calculation, three groups of input data were defined for the comparison of balancing efficiency among the HUST method, the software method, and the method used traditionally by the companies. The line's capacity is determined as the total production amount in a shift, and the shift time is figured accordingly following each factory's rules. The total number of workers is an essential factor. Also, the cycle time is one of the important factors for balancing the sewing line

Thermal effect on magnetoexciton energy spectra in monolayer transition metal dichalcogenides

It is widely comprehended that temperature may cause phonon-exciton scattering, enhancing the energy level's linewidth and leading to some spectrum shifts. However, in the present paper, we suggest a different mechanism that allows the thermal motion of the exciton's center of mass (c.m.) to affect the magnetoexciton energies in monolayer dichalcogenides (TMDCs). By the nontrivial but precise separation of the c.m. motion from an exciton in a monolayer TMDC with a magnetic field, we obtain an equation for the relative motion containing a motional Stark term proportional to the c.m. pseudomomentum, related to the temperature of the exciton gas but neglected in the previous studies. Solving the Schr\"odinger equation without omitting the motional Stark potential at room temperature shows approximately a few meV thermal-magnetic shifts in the exciton energies, significant enough for experimental detection. Moreover, this thermal effect causes a change in exciton radius and diamagnetic coefficient and enhances the exciton lifetime as a consequence. Surprisingly, the thermoinduced motional Stark potential breaks the system's SO(2) symmetry, conducting new peaks in the exciton absorption spectra at room temperature besides those of the $s$ states. This mechanism could be extended for other magnetoquasiparticles such as trions and biexcitons.Comment: 8 pages, 4 figures, 3 tables for main manuscript; 20 pages, 6 figures, 6 tables for supplementary. Published on Physical Review

Retrieval of material properties of monolayer transition-metal dichalcogenides from magnetoexciton energy spectra

Reduced exciton mass, polarizability, and dielectric constant of the surrounding medium are essential properties for semiconduction materials, and they can be extracted recently from the magnetoexciton energies. However, the acceptable accuracy of the previously suggested method requires very high magnetic intensity. Therefore, in the present paper, we propose an alternative method of extracting these material properties from recently available experimental magnetoexciton s-state energies in monolayer transition-metal dichalcogenides (TMDCs). The method is based on the high sensitivity of exciton energies to the material parameters in the Rytova-Keldysh model. It allows us to vary the considered material parameters to get the best fit of the theoretical calculation to the experimental exciton energies for the $1s$, $2s$, and $3s$ states. This procedure gives values of the exciton reduced mass and 2D polarizability. Then, the experimental magnetoexciton spectra compared to the theoretical calculation gives also the average dielectric constant. Concrete applications are presented only for monolayers WSe$_2$ and WS$_2$ from the recently available experimental data. However, the presented approach is universal and can be applied to other monolayer TMDCs. The mentioned fitting procedure requires a fast and effective method of solving the Schr\"{o}dinger of an exciton in monolayer TMDCs with a magnetic field. Therefore, we also develop such a method in this study for highly accurate magnetoexciton energies.Comment: 8 pages, 4 figures, 4 table

Hydrogen Gas Sensing Using Palladium-Graphene Nanocomposite Material Based on Surface Acoustic Wave

We report the fabrication and characterization of surface acoustic wave (SAW) hydrogen sensors using palladium-graphene (Pd-Gr) nanocomposite as sensing material. The Pd-Gr nanocomposite as sensing layer was deposited onto SAW delay line sensor-based interdigitated electrodes (IDTs)/aluminum nitride (AlN)/silicon (Si) structure. The Pd-Gr nanocomposite was synthesized by a chemical route and deposited onto SAW sensors by air-brush spraying. The SAW H2 sensor using Pd-Gr nanocomposite as a sensing layer shows a frequency shift of 25 kHz in 0.5% H2 concentration at room temperature with good repeatability and stability. Moreover, the sensor showed good linearity and fast response/recovery within ten seconds with various H2 concentrations from 0.25 to 1%. The specific interaction between graphene and SAW transfer inside AlN/Si structures yields a high sensitivity and fast response/recovery of SAW H2 sensor based on Pd-Gr/AlN/Si structure

GLUCOSIDES AND UREA DERIVATIVES FROM THE SEEDS OF SCAPHIUM MACROPODUM (MIQ.) BEUMÉE

Five known compounds {carbonylbis[imino(6-methyl-3,1-phenylenel)]}bis[carbamic acid] dimethyl ester (1), (1'R,3'S,5'R,8'S,2E,4E-dihydrophaseic acid) 3'-O-beta-D-glucopyranoside (2), 3-methylbutan-1-ol beta-D-glucopyranoside (3), astragalin (4) and daucosterol (5) were isolated from the methanol extract of the seeds of Scaphium macropodum (Miq.) Beumée. The structures of the isolated compounds were elucidated by the spectroscopic methods including NMR and MS, and also by comparison with the literature data. Compounds 1-3 were isolated from this plant for the first time

Awareness and preparedness of healthcare workers against the first wave of the COVID-19 pandemic: A cross-sectional survey across 57 countries.

BACKGROUND: Since the COVID-19 pandemic began, there have been concerns related to the preparedness of healthcare workers (HCWs). This study aimed to describe the level of awareness and preparedness of hospital HCWs at the time of the first wave. METHODS: This multinational, multicenter, cross-sectional survey was conducted among hospital HCWs from February to May 2020. We used a hierarchical logistic regression multivariate analysis to adjust the influence of variables based on awareness and preparedness. We then used association rule mining to identify relationships between HCW confidence in handling suspected COVID-19 patients and prior COVID-19 case-management training. RESULTS: We surveyed 24,653 HCWs from 371 hospitals across 57 countries and received 17,302 responses from 70.2% HCWs overall. The median COVID-19 preparedness score was 11.0 (interquartile range [IQR] = 6.0-14.0) and the median awareness score was 29.6 (IQR = 26.6-32.6). HCWs at COVID-19 designated facilities with previous outbreak experience, or HCWs who were trained for dealing with the SARS-CoV-2 outbreak, had significantly higher levels of preparedness and awareness (p<0.001). Association rule mining suggests that nurses and doctors who had a 'great-extent-of-confidence' in handling suspected COVID-19 patients had participated in COVID-19 training courses. Male participants (mean difference = 0.34; 95% CI = 0.22, 0.46; p<0.001) and nurses (mean difference = 0.67; 95% CI = 0.53, 0.81; p<0.001) had higher preparedness scores compared to women participants and doctors. INTERPRETATION: There was an unsurprising high level of awareness and preparedness among HCWs who participated in COVID-19 training courses. However, disparity existed along the lines of gender and type of HCW. It is unknown whether the difference in COVID-19 preparedness that we detected early in the pandemic may have translated into disproportionate SARS-CoV-2 burden of disease by gender or HCW type