Preparation and characterization of poly(vinyl alcohol)/sodium alginate/TEMPO-oxidized cellulose nanofiber hydrogel for dye removal

The composite hydrogel of poly(vinyl alcohol) (PVA)/sodium alginate (SA)/TEMPO-oxidized cellulose nanofiber (CNF) was prepared and employed as an effective adsorbent for dye removal. The effect of the weight ratio of incorporated SA and CNF components on the mechanical and dye removal properties of the hydrogel was examined in detail. While the PVA concentration and the SA + CNF concentration were maintained as constant (7.5 and 1.0 wt%, respectively), the weight ratios of SA:CNF were changed from 10:0 to 7:3. Cross-linking of PVA, SA, and CNF were carried out by using boric acid/borax and calcium chloride. The mechanical properties of prepared hydrogels were investigated by a compressive stress test and a durability test under severe agitation in a solution. The PVA/SA hydrogel with no CNF addition (the 10:0 hydrogel) showed the highest compressive strength, and the elastic modulus is approximately 40 times greater than the highest reported value of the conventional PVA hydrogel cross-linked by glutaraldehyde (GA). The hydrogel prepared with SA:CNF ratio of 9:1 (the 9:1 hydrogel) showed the second-highest elastic modulus. In terms of durability, the 9:1 hydrogel was the highest. While the breakage ratio of the 9:1 hydrogel under very severe agitation condition of 2750 rpm was essentially negligible, it was reported that the conventional PVA hydrogel crosslinked with sodium sulfate was completely broken. Even under 3000 rpm, only 12% of the beads were broken for the 9:1 hydrogel. Dye removal experiment was carried out by using methylene blue (MB) as a model dye. The result shows that the highest MB adsorption capacity of 243.9 mg g-1 was obtained for the 9:1 hydrogel. The value was 1.4 times higher than that of the highest reported value for the conventional PVA-based adsorbent. With superior mechanical and dye adsorption properties, the developed PVA/SA/CNF hydrogel can be considered as a potential alternative for dye removal

粒子形状の異なるZnO 光触媒の合成と評価

In recent years, pollution by persistent organic pollutants (POPs) is becoming one of　the severe environmental issues which cause damage to human health. Currently, although ozone　treatment has been employed for POPs removal as an advanced treatment, it has disadvantages　of high costs and production of harmful byproducts. Photocatalysts have been attracting attention　as one of the innovative POPs removal methods. The photocatalyst is a semiconductor that　triggers an oxidation-reduction reaction by light exposure on the particle surface and can achieve　mineralization of pollutants. Although TiO2 is a typical photocatalyst, ZnO has also attracted　attention because of its low costs. Many researchers reported synthesis and characterization of　various ZnO particles with different particle shapes and morphologies using different synthesis　methods. However, comparison of their photocatalytic activity under the same experimental condition　is very limited.Therefore, in this study, we synthesized three different ZnO particles with different particle shapes and morphologies, such as flower-like, multi-shell and rod-like, and compared their particle properties and photocatalytic activities for the same degradation target compound under the same degradation condition. Samples were synthesized by a solvothermal method using Zn(NO3)2･6H2O as raw material. The particle shape was controlled by adding appropriate structure-directing agents. The flower-like, multi-shell and rod-like samples were synthesized by adding hexamethylenetetramine, L(-)-proline and ethanolamine, respectively. The photocatalytic activity was evaluated by degrading 2,4-dinitrophenol (DNP) as a model POPs. Morphologies of the resulting samples were observed by a scanning electron microscope.Based on the SEM observation, it was confirmed that flowerlike, multi-shell and rodlike samples were obtained as expected. The result of X-ray diffraction (XRD) shows that the peaks at 2 θ = 31°, 34°, 36°, 48°, 57°, 63°, 68°, and 69° can be attributed to ZnO. This result indicates that ZnO is successfully obtained by all the synthesis methods. The results also showed that the intensity of the strongest diffraction peak of the three samples varies depending on the ZnO samples in the following order: flower-like < multi-shell < rod-like, and the rod-like sample showed a significantly strong peak intensity among the samples (approximately 15 times larger than that of the flowerlike). On the other hand, the BET specific surface area exhibited a different order: rod-like < multishell < flower-like, and the surface area of the flower-like ZnO was more than 5 times larger than that of the other two samples. These results showed that the strongest peak intensity in XRD measurement and the specific surface area for the three samples are in a trade-off relationship. Finally, photocatalytic activity tests were carried out using 10 ppm DNP under UV light irradiation. The DNP is widely used as an indicator of the photocatalytic activity. The treated water was sampled periodically, and the DNP concentration change as a function of time was determined by measuring the absorption at 357 nm with a UV-vis spectrophotometer. It was found that the DNP degradation fitted the first-order kinetics well for all the samples and the degradation rate was in the following order: rod-like < multi-shell < flower-like. This order is similar to the order for the specific surface area and opposite to that of the strongest peak intensity. The results suggest that the highest photocatalytic activity for DNP degradati on was in the flower-like shape where ZnO contributes a very high specific surface area and not by crystallinity of ZnO

Effect of plastic-type and photocatalyst concentration on plastic film degradation using TIO2

Microplastics, small plastic pieces less than 5 mm in size, are one of the most con- cerning pollutants that can be harmful to the environment and its biota today. Because of their high abundance and small particle size, microplastics are known to be easily ingested by micro organisms and affect many organisms as they move through the food chain. In addition, there is concern that microplastics can be vectors of hazardous substances as they are known to adsorb persistent organic pollutants (POPs) in the environment. However, an efficient treatment method for removing microplastics in wastewater has yet to be established. In recent years, research on introducing photocatalytic o idative degradation systems into wastewater treatment plants (WWTPs) was reported for the potential removal of microplastics from wastewater. Neverthe less, previous reports only focused on developing and evaluating photocatalysts suitable for microplastic degradation, and the e amination of the effects of the types of plastic and photocat alyst concentration on microplastic degradation remains limited. The aim of this study is to eval uate the effect of plastic type and photocatalyst concentration on the degradation of plastic. We used four types of plastic films in the e periment: low-density polyethylene (LDPE), high-den sity polyethylene (HDPE), polypropylene (PP) and polyethylene terephthalate (PET), where the degradation of the plastic was measured by weight. The most used and commercially available TiO2 (P25) was used as a photocatalyst with different concentrations from 0.001 to 1.0 g L-1. The plastic degradation e periment used 3.30 cm squares films with 25 to 30 µm thickness under ultraviolet light irradiation using nine black-light fluorescent lamps (6 W; wavelength: 340-400 nm). The degradation and surface morphology of the plastic film was evaluated by measuring weight loss, carbonyl inde , and scanning electron microscopy. The result showed the LDPE had the highest weight loss compared to other plastic types, which could be due to its simple structure consisting solely of C-H single bonds. Additionally, the highest degradation rate was observed when the photocatalyst concentration was 0.01 g L-1. The reason for the degradation rate decrease at concentrations above 0.01 g L-1 was probably due to the self-light shielding effect of TiO . The low degradation rate at a lower concentration of less than 0.01 g L-1 could be due to insufficient catalyst concentration. In the future, it will be important to analyze the degradation pathways by measuring intermediates during the degrading process for each plastic type.departmental bulletin pape

Graft protective effect and induction of CD4+Foxp3+ cell by Thrombomodulin on allograft arteriosclerosis in mice

Abstract Background Thrombomodulin (TM) is a promising therapeutic natural anti-coagulant, which exerts the effects to control disseminated intravascular coagulation. However, little is known whether TM on micro-vessels could play an important role in the regulation of intimal hyperplasia. We investigated the vessel-protective effect of TM in the survival of fully major histocompatibility complex (MHC)-mismatched murine cardiac allograft transplantation. Methods CBA recipients transplanted with a C57BL/6 heart received intraperitoneal administration of normal saline or 0.2, 2.0, and 20.0 μg/day of TM for 7 days (n = 5, 7, 11, and 11, respectively). Immunohistochemical and fluorescent staining studies were performed to determine whether CD4+Foxp3+ regulatory T cell were generated at 2 and 4 weeks after grafting. Morphometric analysis for neointimal formation in the coronary arteries of the transplanted allograft was conducted at 2 and 4 weeks after grafting. Results Untreated CBA recipients rejected C57BL/6 cardiac grafts acutely (median survival time [MST], 7 days). CBA recipients exposed with the above doses had significantly prolonged allograft survival (MSTs, 17, 24 and 50 days, respectively). Morphometric assessment showed that intimal hyperplasia was clearly suppressed in the left and right coronary arteries or allografts from TM-exposed recipients 2 and 4 weeks. Immunohistochemical studies at 2 weeks showed more CD4+Foxp3+ cells and lower myocardial damage in the allografts from TM-exposed recipients. Notably, fluorescent staining studies demonstrated that TM-exposed recipients 4 weeks post-engraftment had strong aggregation of CD4+Foxp3+ cells in the intima of the coronary arteries of the cardiac allografts. Conclusions TM may prolong the survival of fully MHC-mismatched cardiac allografts through suppressing intimal hyperplasia and inducing the accumulation of regulatory CD4+Foxp3+ cells within coronary arteries

Spatial and time-resolved properties of emission enhancement in polar/semi-polar InGaN/GaN by surface plasmon resonance

Light-emitting diodes (LEDs) are widely used as next-generation light sources because of their various advantages. However, their luminous efficiency is remarkably low at the green-emission wavelength. The luminous efficiencies of InGaN/GaN quantum wells (QWs) significantly decrease with increasing indium content in the green wavelength region, mainly owing to the quantum-confined Stark effect (QCSE). This green gap problem can be solved using QWs grown on semi-polar GaN substrates, such as the {11–22} planes, to reduce the QCSE. We propose that the use of surface plasmons (SPs) is a promising way to improve the light emission efficiency of light-emitting materials such as InGaN/GaN QWs. SP resonance increases the spontaneous emission rates of the excited states, causes a relative reduction in non-radiative relaxation, and ultimately increases the internal quantum efficiencies. In this study, the light emissions of InGaN/GaN QWs grown on polar and semi-polar GaN were investigated using micro-photoluminescence (PL). We successfully enhanced the light emission of semi-polar GaN via SP resonance. The PL peak intensities and wavelengths were mapped and compared to determine the underlying mechanisms. We also measured the emission lifetimes by time-resolved PL and interpreted the detailed mechanism of SP-enhanced emissions. It was found that SP resonances can control not only the emission efficiency but also the exciton dynamics, such as exciton localization effects, QCSE screening, and defect level saturation. We conclude that the green gap problem can be solved by SP-enhanced light emission in semipolar InGaN/GaN

Hardware-oriented stereo vision algorithm based on 1-D guided filtering and its FPGA implementation,&quot;ICECS

Abstract-This paper presents a novel hardware-oriented stereo vision system based on 1-D cost aggregation. Many researchers have implemented hardware efficient stereo matching to realize real-time systems. However, such methods require a large amount of memory. We proposed a system that is based on a hardware-software hybrid architecture for memory reduction. It consisted of grayscale 1-D cost aggregation HW and 2-D disparity refinement SW. The 1-D processing reduced the size of RAM in our HW to 266 kb with an input image size of 1024×768. We achieved the average error rate for the Middlebury datasets as 6.24%. The processing time was 56.6 ms for the 1024×768 images and an average of 8.6 ms for the Middlebury datasets which have an average size of 400×380. Using the resolution of Middlebury datasets, our system can perform real-time depth-aided image processing