Details of a Researcher - SAKAI Kentaro

Development of Borehole Seismometer Using Conical Pendulum to Three-Component Velocity Measurement Reviewed

Yoshimatsu Akito, Bonkobara Yasuhiro, Ueoka Nobo, Hamahata Takayuki, Sakai Kentaro, Nakano Atsushi, Terazono Shinichi

Memoirs of Faculty of Engineering, University of Miyazaki 52 65 - 69 2023.10

Language：Japanese Publishing type：Research paper (scientific journal)

Dopant-induced photodegradation of organic water pollutants using cobalt oxide nanostructures of low cytotoxicity Reviewed International coauthorship

Ranjitha R., Dileep Kumar V.G., Navada M.K., Shetty S.M., Jayanna B.K., Bhatt A.S., Santosh M.S., Madhyastha H., Sakai K., Ravikumar C.R.

Journal of Environmental Chemical Engineering 11 ( 2 ) 2023.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Environmental Chemical Engineering

Metal oxides are the simplest and most approachable solutions for attaining multifunctional properties applicable to modern-day technology. With growing concern over environmental conservation, an evaluation of the cytotoxicity of the metal oxides becomes necessary. The present work focuses on the photocatalytic and cytocompatibility behavior of Co3O4 nanomaterial. It has been observed that the addition of Li to the Co3O4 nanostructure generates a positive impact on the photodegradation of cationic dyes under UV light. The photocatalyst with 1 wt% Li-doped Co3O4 was found to be the most competent among the synthesized samples. Further, the sample has been employed for photocatalytic removal of the hazardous pollutant, pyrocatechol (PyC), in the presence of visible light. A photocatalytic efficiency of 84.5% (after 9 h) and high stability (86% after 5 cycles) is observed. A noteworthy revelation is the lower toxicity observed for Li-doped samples when compared to the pristine Co3O4. The (3-(4,5-dimethylthiazolyl-2)− 2,5-diphenyltetrazolium bromide) (MTT) assay carried out on mouse skin fibroblast cell lines reveals cytotoxicity inhibition by the doped nanostructures for up to 10 μg mL−1 concentration and excellent cell proliferation up to 24 h. The superior catalytic behavior and non-toxic nature of the Li-doped Co3O4 nanostructures provide ample opportunity for their integration into water remediation and effluent treatment systems.

DOI： 10.1016/j.jece.2023.109520

Fine Particle Adsorption Capacity of Volcanic Soil from Southern Kyushu, Japan Reviewed

Naoaki Misawa, Kentaro Yasui, Kentaro Sakai, Taichi Kobayashi, Hideki Nagahama, Tomohiro Haraguchi, Satomi Sasaki, Vetchapitak Torrung, Taradon Luangtongkum, Takako Taniguchi, Kentaro Yamada, Makoto Minamimagari, Toshihiro Usami, Hiroyuki Kinoshita

Nanomaterials 13 ( 3 ) 568-1 - 568-19 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Nanomaterials

“Akahoya” is a volcanic soil classified as a special soil deposited in Kyushu, Japan. Many of its properties are not yet clearly understood. We found that Akahoya had the potential to adsorb bacteria in cattle feces, which prompted us to investigate its material properties and perform experiments to comprehensively evaluate its adsorption performance for various fine particles such as acidic and basic dyes, NOx/SOx gas, and phosphoric acid ions, in addition to bacteria. Akahoya had a very high specific surface area owing to the large number of nanometer-sized pores in its structure; it exhibited a high adsorption capacity for both NO2 and SO2. Regarding the zeta potential of Akahoya, the point of zero charge was approximately pH 7.0. The surface potential had a significant effect on the adsorption of acidic and basic dyes. Akahoya had a very high cation exchange capacity when the sample surface was negatively charged and a high anion exchange capacity when the sample surface was positively charged. Akahoya also exhibited a relatively high adsorption capacity for phosphoric acid because of its high level of Al2O3, and the immersion liquid had a very high Al ion concentration. Finally, filtration tests were performed on Escherichia coli suspension using a column filled with Akahoya or another volcanic soil sample. The results confirmed that the Escherichia coli adhered on the Akahoya sample. The results of the Escherichia coli release test, after the filtration test, suggested that this adhesion to Akahoya could be phosphorus-mediated.

DOI： https://doi.org/10.3390/nano13030568

Dual antibacterial and anti-inflammatory efficacy of a chitosan-chondroitin sulfate-based in-situ forming wound dressing. Reviewed International coauthorship

Sharma S, Madhyastha H, Kirwale SS, Sakai K, Katakia YT, Majumder S, Roy A

Carbohydrate polymers 298 120126 2022.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Carbohydrate Polymers

None of the currently available wound dressings exhibit combined antibacterial and anti-inflammatory activity. Using polyelectrolyte complexation (PEC) between a cationic polysaccharide chitosan (CH) and an anionic glycosaminoglycan chondroitin sulfate (CS), we have developed a unique in-situ forming scaffold (CH-CS PEC), which develops at the wound site itself to influence the function of the wound bed cells. The current study demonstrated that CH-CS PEC could induce bacterial cell death through membrane pore formation and increased ROS production. Moreover, possibly due to its unique material properties including medium-soft viscoelasticity, porosity, and surface composition, CH-CS PEC could modulate macrophage function, increasing their phagocytic ability with low TNF-α and high IL-10 production. Faster wound closure and decreased CFU count was observed in an in-vivo infected wound model, with reduced NF-κB and increased VE-cadherin expression, indicating reduced inflammation and enhanced angiogenesis. In summary, this study exhibited that CH-CS PEC has substantial antibacterial and immunomodulatory properties.

DOI： 10.1016/j.carbpol.2022.120126

Dural Changes Induced by an Ultrasonic Bone Curette in an Excised Porcine Spinal Cord Reviewed

Ota Rizou, Iwaki Eri, Sakai Kentaro, Haraguchi Tomohiro, Kaneko Yasuyuki, Sekiguchi Satoshi, Yamaguchi Ryoji, Naganobu Kiyokazu

Veterinary Sciences 9 ( 11 ) 601-1 - 601-11 2022.10

Language：English Publishing type：Research paper (scientific journal)

In spinal surgery, ultrasonic bone curettes are considered unlikely to cause mechanical injury to the dura; however, there is little evidence to support this claim. We investigated the effect of direct contact with an ultrasonic bone curette on the dura and the protective effect of covering the dura with a cotton pattie using an excised porcine spinal cord. The ultrasonic bone curette was pressed against the porcine spinal cord with constant force and activated for 1 s, with or without covering the dura with a cotton pattie. The dural surface and cross-section were observed using electron and light microscopy. When the ultrasonic bone curette was applied directly against the dura, most specimens showed non-perforating dural injuries. However, none of the specimens showed dural perforation. Histological changes were also observed. The use of a cotton pattie reduced the occurrence of these changes, although it did not prevent them when ultrasonic vibration was applied with a large force. We considered ultrasonic bone curettes to have a low risk of dural perforation and, thus, to be a safe surgical device as long as they did not accidentally make strong contact with the dura.

DOI： https://doi.org/10.3390/vetsci9110601

Designer exosomes: Smart nano-communication tools for translational medicine Reviewed International coauthorship

Harishkumar M., Radha M., Yuichi N., Muthukalianan G.K., Kaoru O., Shiomori K., Sakai K., Nozomi W.

Bioengineering 8 ( 11 ) 2021.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Bioengineering

Exosomes are the master transporters of genes, RNAs, microRNAs, proteins, and lipids. They have applications in major diseases, including cancer, cardiovascular diseases, neurological disorders, and diabetes mellitus. Delivery of the exosomes to recipient cells is governed by the functional heterogenicity of the tissues. Engineered exosomes are promising tools in tissue regeneration. In addition to their role as intracellular communication cargos, exosomes are increasingly primed as standard biomarkers in the progression of diseases, thereby solving the diagnostic dilemma. Futuris-tic empowerment of exosomes with OMICS strategy can undoubtedly be a bio-tool in translational medicine. This review discusses the advent transformation of exosomes in regenerative medicine and limitations that are caveats to broader applications in clinical use.

DOI： 10.3390/bioengineering8110158

Sr Composition Dependence of the Trap Level in Strontium Aluminate Prepared by Combustion Synthesis Reviewed

Kodama Naoya, Yokoyama Hirosumi, Sakai Kentaro, Masumoto Yuta

Memoirs of Faculty of Engineering, University of Miyazaki 50 55 - 58 2021.9

Language：Japanese Publishing type：Research paper (scientific journal)

Performance evaluation and spectrum-based analysis of a wall-mounted photovoltaic system for zero-energy building Reviewed

Nagaoka A., Ota Y., Sakai K., Araki K., Matsuo H., Kadota N., Maeda K., Nakajima A., Nishioka K.

Renewable Energy 174 147 - 156 2021.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Renewable Energy

The concept of zero-energy building (ZEB) has attracted global attention in recent years as it involves offsetting the primary energy usage of a building on an annual base by the energy generated from renewable resources. The performance of wall-mounted photovoltaics (PV) for building applications has great potential for ZEB. In this study, we compared wall-mounted and common roof-mounted PV systems using a combination of experimental and theoretical studies. The wall-mounted PV system exhibited an unusual performance behavior depending on the season. Winter is a suitable season for energy production from the wall-mounted PV system because of the low solar altitude and resulting lower incident angle of the sun. However, the performance ratio (PR) had twin peaks throughout the day that could not be explained by the classical model that uses irradiance and temperature variation. In summer, there was less irradiance on the vertical wall and the PR had triple peaks that were also hard to explain using the conventional model. We established a detailed output power model of the wall-mounted PV using spectrum variation on a vertical plane. Our approach is the development of spectrum model that can be applied to all-climate and computed the performance variation according to the sun's orientation and incident angle. Our model quantitatively explains unique seasonal and daily efficiency variations for the wall-mounted PV system (twin peaks in winter and triple peaks in summer). Our validated model can be utilized to map a suitable location for a wall-mounted PV system.

DOI： 10.1016/j.renene.2021.04.079

Evaluation of rate of adhesion of Lactobacillus namurensis strain GYP-74 to porous fine ceramics Reviewed

Taoka Y., Sakai K., Kinoshita H., Fukuyama H., Kobayashi T., Hirano A., Kuroki N., Kuroki M., Kimura A.

Processes 9 ( 4 ) 2021.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Processes

This study aimed to evaluate the ratio of adherence of lactic acid bacteria (LAB) to porous fine ceramics in order to develop a novel LAB-rich pickle container for the production of functional fermented vegetables. Some LAB were isolated from the salted rice bran used for pickling (Nukadoko in Japanese). These isolates were classified in Lactobacillus namurensis by phylogenetic analysis. Some pottery-shard (PS) samples were prepared by varying the mixing rate of polyacetal (POM) resin to clay (0-30% (v/v)) and the burning temperature (1000 °C or 1100 °C). A test of the adherence of strain GYP-74 to the PSs was performed. The results showed that the adherence rate was significantly higher in the PSs burned at 1100 °C as compared with those burned at 1000 °C. A pore distribution analysis showed that pore sizes of less than a few µm and pore sizes in the range of a few µm to a few hundred µm were mainly distributed in the PSs without and with POM, respectively. X-ray diffraction analysis showed that both PSs with and without POM contained quartz and hematite. The PSs burned at 1000 °C and 1100 °C specifically contained microcline and mullite, respectively. This study revealed the basal information regarding what makes PSs adequate for LAB adhesion.

DOI： 10.3390/pr9040658

Rapid photocatalytic degradation of cationic organic dyes using Li-doped Ni/NiO nanocomposites and their electrochemical performance Reviewed International coauthorship

R. Ranjitha, K. N. Meghana, V. G. Dileep Kumar, Aarti S. Bhatt, B. K. Jayanna, C. R. Ravikumar, Mysore Sridhar Santosh, H. Madhyastha, K. Sakai

New Journal of Chemistry 45 ( 2 ) 796 - 809 2020.12

Language：English Publishing type：Research paper (scientific journal) Publisher：New Journal of Chemistry

Metal/metal oxide nanocomposites (NCs) have been attracting significant attention in recent times because of their applications in the fields of energy and environment. In the present work, we investigate the photocatalytic and electrochemical performances of Ni/NiO NCs synthesized by a facile and cost-effective reduction method using lithium salt as the dopant. Lithium influences the size, morphology and structural constitution of the final product. A variation in the lithium percentage was seen to have a direct effect on the Ni content. The structural conformation of the samples has been analyzed by XRD and further confirmed by XPS. A low optical energy bandgap (∼3.7 eV) and a mesoporous structure of the as-prepared samples were seen to play a crucial role in achieving the photocatalytic degradation of the cationic organic dyes concomitant to its electrochemical activity. On illumination with UV light, the Li-doped Ni/NiO NCs demonstrated rapid degradation of crystal violet and methyl violet 2B dyes. The synergism arising due to the substitutional doping of lithium and the presence of metallic nickel leads to efficient photodegradation of the dye pollutants by the catalysts. Further, the Li-doped Ni/NiO NCs displayed a better electrochemical performance than the undoped samples. The NC with 1 wt% Li exhibited the best values of specific capacitance (276.2 F g-1 at 5 A g-1) with an excellent cycling ability (<1% capacitance loss after 2000 cycles). The enhanced electrochemical and photocatalytic results suggest the dual activity of these nanocomposites in energy storage and water treatment applications. This journal is

DOI： 10.1039/D0NJ05268J

Biosynthesis and characterization of nano magnetic hydroxyapatite(nMHAp): An accelerated approach using simulated body fluid for biomedical applications Reviewed International coauthorship

Akshay Bhatt, Kentaro Sakai, Radha Madhyastha, Masugi Murayama, Harishkumar Madhyastha, Subha Narayan Rath

Ceramics International 46 ( 17 ) 27866 - 27876 2020.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Ceramics International

There are several metal ions including iron oxide nanoparticles, which has been used for doping hydroxyapatite to overcome the existing shortcoming associated with poor mechanical strength, less bioactivity and inert properties. Iron oxide nanoparticles, commonly known as magnetite, has shown a great potential in tissue engineering and various other biomedical applications. It has been proven that small quantity of iron increases the mechanical properties as well antioxidative property of the material. Magnetic hydroxyapatite is synthesized by many different synthesis routes such as hydrothermal, spray drying, ultrasonic irradiation etc. These synthesis routes are time consuming and requires sophisticated process parameters. Hence, to overcome these complexities, this study aims to synthesize and characterize nano magnetic hydroxyapatite (nMHAp) in a shorter duration than the conventionally used duration (over 24 h) through a novel bio-mimetic approach. The physicochemical properties were checked using XRD, FTIR, TGA, XPS, DLS, SEM, TEM and VSM. The results suggest that synthesized nMHAp contains magnetic properties and resembles carbonated apatite with the traces of Na, Mg, K, Cl and Fe. SEM and TEM analysis confirmed the spherical nature of nMHAp with average size between 10 and 200 nm. The optimized average time for nMHAp synthesis was found to be 3 h. Cellular biocompatibility and the measurement of reactive oxygen species using L929 cells confirmed the biocompatible and antioxidative nature of nMHAp. Hence, Our studies show that the nMHAp can be synthesized biomimetically in 3 h and potentially could be used for bone tissue engineering and other biomedical applications.

DOI： 10.1016/j.ceramint.2020.07.285

c-Phycocyanin primed silver nano conjugates: Studies on red blood cell stress resilience mechanism Reviewed

Madhyastha H, Madhyastha R, Thakur A, Kentaro S, Dev A, Singh S, Chandrashekharappa R B, Kumar H, Acevedo O, Nakajima Y, Daima HK, Aradhya A, Nagaraj P N, Maruyama M

Colloids and surfaces. B, Biointerfaces 194 111211 2020.10

Language：Japanese Publishing type：Research paper (scientific journal)

DOI： 10.1016/j.colsurfb.2020.111211

Mechano-luminescence properties of rare-earth doped strontium aluminate phosphor prepared by gel-combustion method Reviewed

Kodama Naoya, Matsumoto Kazuma, Yokoyama Hirosumi, Sakai Kentaro

Memoirs of Faculty of Engineering, University of Miyazaki 49 61 - 64 2020.9

Language：Japanese Publishing type：Research paper (scientific journal)

Correlation between mechano-luminescence and activation energy of trap level in sulfur and fluorine doped strontium aluminate phosphor Reviewed

Matsumoto Kazuma, Kodama Naoya, Yokoyama Hirosumi, Sakai Kentaro

Memoirs of Faculty of Engineering, University of Miyazaki 49 65 - 68 2020.9

Language：Japanese Publishing type：Research paper (scientific journal)

Construction of a Facility Sharing System in University of Miyazaki:—Development of a common facility management system linked on-line to existing campus management system— Reviewed

SAKAI Kentaro, IMAI Masato, IZUMI Nobuo, KOURIKI Haruna, KUNITAKE Hisato, MISAWA Naoaki, SUIKO Masahito

The Journal of Science Policy and Research Management 35 ( 1 ) 23 - 31 2020.5

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society for Research Policy and Innovation Management

Recently, many universities have been working to promote the sharing of research facilities and equipment in Japan. University of Miyazaki is also developing a sharing service system of those through two projects supported by the Ministry of Education, Culture, Sports, Science and Technology. In addition, we have established the Miyazaki Facility Network, in which public research institutions in Miyazaki Prefecture participate, and are working to create an environment that can provide mutually advanced analysis technologies that contribute to regional revitalization.In this paper, we introduce a common facilities management system linked on-line to the existing financial accounting and the researcher database developed by University of Miyazaki, and describe the relationship with the administration policy of our university and examples of utilization in Miyazaki prefecture.

DOI： 10.20801/jsrpim.35.1_23

Electroactive Li incorporated cobalt oxide nanostructures for photocatalytic applications Reviewed

R. Ranjitha, Aarti S. Bhatt, C. R. Ravikumar, M. S. Santosh, B. K. Jayanna, H. P. Nagaswarupa, K. Sakai and H. Madhyastha

Materials Research Express 6 ( 11 ) 1150d6-1 - 1150d6-13 2019.11

Language：English Publishing type：Research paper (scientific journal)

DOI： 10.1088/2053-1591/ab5033

Screening of lactic acid bacteria isolated from fermented food as potential probiotics for aquacultured carp and amberjack Reviewed

N.T.H. Linh, K. Sakai, Y. Taoka

Fisheries Science 84 101 - 111 2018.1

Language：English Publishing type：Research paper (scientific journal)

DOI： 10.1007/s12562-017-1150-9

Photoluminescence emission from GaAs nanodisks in GaAs/AlGaAs nanopillar arrays fabricated by neutral beam etching Reviewed

Ohori D., Fukuyama A., Sakai K., Higo A., Thomas C., Samukawa S., Ikari T.

Japanese Journal of Applied Physics 56 ( 5 ) 2017.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics

© 2017 The Japan Society of Applied Physics. GaAs quantum nanodisks (QNDs) in nanopillar (NP) arrays are considered to be an attractive candidate for photonic device applications. We report a damageless fabrication technique that can be used to produce large-area lattice-matched GaAs/AlGaAs heterostructure NP arrays through the use of a bio-template and neutral beam etching. We have successfully realized GaAs QNDs in NPs owing to nanoscale iron oxide masks included in poly(ethylene glycol)-decorated ferritin protein shells. We observed for first time the photoluminescence emission from asetched GaAs QNDs and confirmed quantum confinement by quantum mechanical calculation. Our methodology is vital for high-efficiency pillarbased optoelectronic devices such as NP laser diodes.

DOI： 10.7567/JJAP.56.050308

Material conversion of GaAs nanowires Reviewed

K. Nishioka, H. Suzuki, K. Sakai, F. Ishikawa

Physica Status Solidi (B) 254 1600522-1 - 1600522-5 2017.2

Language：English Publishing type：Research paper (scientific journal)

DOI： 10.1002/pssb.201600522