Amphiphilic graft copolymers: Effect of graft chain length and content on colloid gel

Nitta, Kyohei,Kimoto, Atsushi,Watanabe, Junji,Ikeda, Yoshiyuki Techno-Press 2015 Biomaterials and biomedical engineering Vol.2 No.2

A series of amphiphilic graft copolymers were synthesized by varying the number of graft chains and graft chain lengths. The polarity of the hydrophobic graft chain on the copolymers was varied their solution properties. The glass transition temperature of the copolymers was in the low-temperature region, because of the amorphous nature of poly (trimethylene carbonate) (PTMC). The surface morphology of the lyophilized colloid gel had a bundle structure, which was derived from the combination of poly(N-hydroxyethylacrylamide)( poly(HEAA)) and PTMC. The solution properties were evaluated using dynamic light scattering and fluorescence measurements. The particle size of the graft copolymers was about 30-300 nm. The graft copolymers with a higher number of repeating units attributed to the TMC (trimethylene carbonate) component and with a lower macromonomer ratio showed high thermal stability. The critical association concentration was estimated to be between $2.2{\times}10^{-3}$ and $8.9{\times}10^{-2}mg/mL$, using the pyrene-based fluorescence probe technique. These results showed that the hydrophobic chain of the graft copolymer having a long PTMC segment had a low polarity, dependent on the number of repeating units of TMC and the macromonomer composition ratio. These results demonstrated that a higher number of repeating units of TMC, with a lower macromonomer composition, was preferable for molecular encapsulation.

문법과 사서 : 동사의 기술을 중심으로

Nitta, Yoshio 한국일어일문학회 1996 日語日文學硏究 Vol.29 No.1

Amphiphilic graft copolymers: Effect of graft chain length and content on colloid gel

Nitta, Kyohei,Kimoto, Atsushi,Watanabe, Junji,Ikeda, Yoshiyuki Techno-Press 2015 Biomaterials and Biomechanics in Bioengineering Vol.2 No.2

A series of amphiphilic graft copolymers were synthesized by varying the number of graft chains and graft chain lengths. The polarity of the hydrophobic graft chain on the copolymers was varied their solution properties. The glass transition temperature of the copolymers was in the low-temperature region, because of the amorphous nature of poly (trimethylene carbonate) (PTMC). The surface morphology of the lyophilized colloid gel had a bundle structure, which was derived from the combination of poly(N-hydroxyethylacrylamide)( poly(HEAA)) and PTMC. The solution properties were evaluated using dynamic light scattering and fluorescence measurements. The particle size of the graft copolymers was about 30-300 nm. The graft copolymers with a higher number of repeating units attributed to the TMC (trimethylene carbonate) component and with a lower macromonomer ratio showed high thermal stability. The critical association concentration was estimated to be between $2.2{\times}10^{-3}$ and $8.9{\times}10^{-2}mg/mL$, using the pyrene-based fluorescence probe technique. These results showed that the hydrophobic chain of the graft copolymer having a long PTMC segment had a low polarity, dependent on the number of repeating units of TMC and the macromonomer composition ratio. These results demonstrated that a higher number of repeating units of TMC, with a lower macromonomer composition, was preferable for molecular encapsulation.

Analysis of contact stiffness between metal ground surfaces using thin PET film

NItta Isami,Hasegawa, Takashi ENGINEERING TRIBOLOGY RESEARCH INSTITUTE KYUNGPOOK 1999 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.1999 No.-

In a previous paper, we developed a thin polymer film method which was able to measure the real contact area. In this polymer film method was used to analyze the contact stiffness. In unloading and reloading processes, the real contact area and its distribution were measured by this method at each load. As a result, it turned out the non-uniform contact over the apparent contact area at the low normal load corresponded to rapid change in the contact stiffness. As the normal load was increased, the contact condition gradually approached the uniform contact, leading the contact stiffness to almost constant value. These measurements by the thin polymer film method indicated that the waviness had strongly influenced the contact stiffness more than the surface roughness did. In addition, we carried out the numerical simulation of the contact stiffness on the consideration of only the waviness. The simulated results were in good agreement with the experimental results.

Weight Gain and Alcohol Drinking Associations with Breast Cancer Risk in Japanese Postmenopausal Women - Results from the Japan Collaborative Cohort (JACC) Study

Nitta, Junichi,Nojima, Masanori,Ohnishi, Hirofumi,Mori, Mitsuru,Wakai, Kenji,Suzuki, Sadao,Fujino, Yoshihisa,Lin, Yingsong,Tamakoshi, Koji,Tamakoshi, Akiko Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.3

Background: We investigated four factors, height, weight gain since age 20, physical activity, and alcohol drinking, for associations with risk of breast cancer (BC) according to menopausal status, using the latest data of the Japan Collaborative Cohort Study (JACC Study). Materials and Methods: We confined the analysis to 24 areas available of cancer incidence information, excluding women with a previous diagnosis of BC. Baseline data were collected from 38,610 (9,367 premenopausal, and 29,243 postmenopausal) women during 1988 and 1990. The study subjects were followed-up at the end of 2009, and 273 (84 premenopausal, and 189 postmenopausal) cases of BC were newly diagnosed in 501,907 person-years. The Cox model was used to estimate a hazards ratio (HR) and its 95% confidence interval (CI) of BC risk. Results: As a result of the multivariate analysis adjusting for age at baseline survey, age at menarche, number of live births, and, age at first delivery, weight gain since age 20 of 6.7 kg-9.9 kg, and ${\geq}10.0kg$ were significantly associated with increased risk for postmenopausal BC (HR=2.48, 95% CI 1.40-4.41, and, HR=2.94, 95% CI 1.84-4.70, respectively). Significantly increased trend of BC risk was also observed in weight gain since age 20 (p for trend, p<0.001). Amount of ethanol intake per day${\geq}15.0g$ was significantly associated with increased risk for postmenopausal BC in the multivariable-adjusted analysis (HR=2.74, 95% CI 1.32-5.70). Conclusions: Higher weight gain in adulthood and larger amounts of ethanol intake were significantly associated with increased risk of BC in Japanese postmenopausal women. None of the investigated factors were significantly associated with BC risk in Japanese premenopausal women.

MOESP Approach for Designing a Compensation Input to Linear Unknown SISO Systems

Masuhiro Nitta 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

This paper deals with a compensation method for linear unknown single-input-single-output systems. A mechanical system is often suffered by frictions, so that aging degradation is unavoidable. If the original controller does not bring out a control performance, controller redesign is demanded. However it sometimes degrades the control performance due to variance of the system dynamics. The present paper considers supplying the system with a compensation input satisfying the control performance. Since the transfer function of the system is unknown, we apply a test signal merely one-time and observe its response to get hold of the system characteristics. From this once trial, several pairs of the input-output signals are generated by applying the MOESP approach. Lack of control performance, which appears on the output channels, is compensated by a linear mixture of the generated output signals. By using the mixing coefficient, the compensation input signal is back calculated. Effectiveness of the proposed design method is demonstrated through numerical simulations.

Output Voltage Control of Hydrogen Engine Generator using A Hill Climbing Method by Adjusting the Hydrogen Flow Rate with A Proportional Control Valve

Hikari Nitta,Nobukazu Hoshi,Koki Ishizuka,Kazuhito Fukuda 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Hydrogen engine generator has attracted attention because it is cheaper than fuel cells and does not emit CO₂. However, hydrogen flow rate must be controlled appropriately according to output power, which changes depending on the load. If the hydrogen flow rate input into the engine was not controlled appropriately, the output voltage is dropped or the fuel efficiency becomes worse. In this paper, output voltage control of a hydrogen engine generator using a hill climbing method with an evaluation function simulating a quadratic function is proposed. It is clarified by experiments that the output voltage of the generator can be controlled to a constant value by applying the hill climbing method with the evaluation function even when the load fluctuates. In addition, it is shown that the response time can be shortened by 0.4 sec with the same system configuration as the previously proposed PI controlled system.

Cultivation History Entry System for Agricultural Products

Hitoshi Nitta,Hiroki Takeda,Teruhisa Hochin 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7

Pesticide legislation in Japan is very complex. It is a virtually impossible task that the farmer understands all of this law. To solve this problem, the authors have developed “Cultivation History Entry System for Agricultural Products”. Even the farmer who does not completely understand pesticide legislation comes to be able to do farm works that uphold pesticide legislation by using this system. This system equips improved usability by adoption of AJAX (Asynchronous JavaScript+XML) technology. Because this technology enables a server access without screen transition, this system is superior to the past system for agricultural products in response performance and visibility.

Preparation of hydrogel using catechin-grafted chitosan and carboxymethyl cellulose

Sachiko Nitta,Sakura Taniguchi,Hiroyuki Iwamoto 한국고분자학회 2024 Macromolecular Research Vol.32 No.7

Developing a novel approach for the administration of catechin that ensures sustained bioactivity, even at low doses, is crucial. In this regard, hydrogels were synthesized by polyion complexation of carboxymethyl cellulose (CMC) and chitosan (CS) grafted with epigallocatechin gallate (EGCG-g-CS), which can maintain enduring antioxidant activity. We initially synthesized grafted chitosan with various grafting ratios using a free-radical grafting method. Polyionic complexes were formed by ionic bonding of the amino groups in EGCG-g-CS with the carboxyl groups in CMC. After lyophilization, a hydrogel with a porous structure was obtained. Scanning electron microscopy (SEM), thermogravimetric differential thermal analysis (TG–DTA), and Fourier transform infrared (FT-IR) analyses of the gel structures were conducted. The swelling properties and porosity of the hydrogels were affected by the grafting ratio. The hydrogel gradually released EGCG under low pH conditions owing to chitosan solubilization, resulting in hydrogel disintegration. Additionally, the hydrogels demonstrated cell adhesion and viability. This study suggests that bio-based materials have potential as pH-dependent catechin-releasing materials.

Comparing Minimum Wage Setting Mechanisms in Japan and Korea: Searching for the Sources of Difference

Michio Nitta,Jongwon WOO 한국고용노사관계학회 2019 産業關係硏究 Vol.29 No.1

The paper examines developments on minimum wage setting mechanisms (MWSM) in Japan and Korea in recent years, focusing on institutions, processes and outcomes of MWSM. Such attributes of the institution are examined as the basic minimum wage setting structures, the constitutions and deliberation procedures of the consultative bodies, and the factors considered in deciding annual minimum wage deliberation. Some similarities are found. Both countries heavily rely on tripartite committees at the national level. Besides, both governments try to influence minimum wage setting procedures by indicating higher minimum wage is desirable. Contrarily, some differences are discovered. One difference is shown in the process of MWSM: it is much tougher in Korea than Japan. Another difference is observed in the outcome of MWSM: the minimum wages have increased much faster and higher in Korea than in Japan. From a system perspective, the differences may be related to what factors minimum wage setting organizations consider. While income distribution is one of the important factors to be considered in Korea, it is not the case in Japan. It seems that the Korean MWSM is assigned a wider role to reduce income gap among workers, while the Japanese counterpart is allowed to focus more on specifically low wage group of workers. The authors remind people of policy circles of the importance of wider perspective in examining performance of minimum wage policy. A minimum wage policy may produce expected results under certain circumstances and may not under other conditions. In order to reach a conclusion, one needs to consider wide range of related policies besides economic/social factors.