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Search Results: 1 - 10 of 481 matches for " Goro Yamauchi "
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The Synergistic Antibacterial Performance of a Cu/WO3-Added PTFE Particulate Superhydrophobic Composite Material  [PDF]
Kentaro Yamauchi, Tsuyoshi Ochiai, Goro Yamauchi
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2015, DOI: 10.4236/jbnb.2015.61001
Abstract: The synergistic antibacterial performance against Escherichia coli (E. coli), Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) of a Cu/WO3-added PTFE (polytetrafluoroethylene) particulate composite was reported in the previous paper. The origin of the synergistic antibacterial performance investigated by evaluating the photocatalytic decomposition of the Cu/WO3-added PTFE particulate composite material is reported in the present paper. Addition of Cu/WO3, visible-light-sensitive photocatalyst, to the PTFE particle dispersed superhydrophobic composite does not deteriorate the superhydrophobic property of the composite. Furthermore the existence of the polytetrafluoroethylene (PTFE) particles dispersed in the composite enhances the antibacterial property caused by the Cu/WO3. The authors call this “The synergistic effect”. In this study, a novel synergistic property of the Cu/WO3-added PTFE particulate composite was investigated by evaluating the degradation of gaseous acetaldehyde on the composite surface using visible light (10,000 lx) and UV-A (1 mW·cm-1) illumination. The 12 wt% Cu/WO3-8 wt% binder-80 wt% PTFE composite shows the synergistic visible-light-sensitive photocatalytic property. But 12 wt% Cu/WO3-44 wt% PTFE-44 wt% binder composite no longer shows the synergistic property of visible-light-sensitive photocatalytic property. The synergetic performance of visible-light-sensitive photocatalytic property appears only when PTFE concentration is larger than the critical point over which superhydrophobic property appears in accordance with the particulate composite model derived by the one of the authors. The hydrophobic surface leads to the low surface free energy derived by the revised Fowkes’s theory, which makes it difficult for bacteria to stick to the hydrophobic surface of the composite. Even if bacteria stick to the surface, they are decomposed by the visible-light-sensitive photocatalyst. This is the reason why the synergistic antibacterial performance against bacteria appears.
Synergistic Antibacterial Performance of a Cu/WO3-Added PTFE Particulate Superhydrophobic Composite under Visible-Light Exposure  [PDF]
Yanyan Yao, Kentaro Yamauchi, Goro Yamauchi, Tsuyoshi Ochiai, Taketoshi Murakami, Yoshinobu Kubota
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2012, DOI: 10.4236/jbnb.2012.34042
Abstract: Addition of TiO2 to a polytetrafluoroethylene (PTFE) particle-dispersed composite contributes to the self-cleaning properties of the water-repellent composite. However, its application is limited to outdoor usage or under ultraviolet (UV) irradiation. In this study, a novel visible-light-sensitive photocatalytic and superhydrophobic material was developed by adding Cu/WO3 to a PTFE particulate composite material to overcome this deficit. A remarkable property of this novel composite material is the synergistic antibacterial performance against Escherichia coli (E. coli), Staphylo-coccus aureus, and methicillin-resistant Staphylococcus aureus compared with the addition of Cu/WO3 without PTFE particles material. During 24-h exposure in visible light at 2000 lx, the number of viable cells of the three strains on the surface of the 8wt% Cu/WO3-added PTFE particulate composite decreased from 2 – 4 × 105 colony-formation units (CFUs) to less than 10, the limit of detection. This bactericidal rate is four times higher than that of 8wt% Cu/WO3 without PTFE particles material, which is attributed to the air trapped in the rough surface of the novel material providing additional oxygen to the photocatalytic reaction. Even for exposure to visible light at 100 lx, the decrease in CFUs of E. coli on the 12wt% Cu/WO3-added PTFE particulate composite reached nearly 2.0 logs. The characterization of the Cu/WO3-added PTFE particulate composite indicated that the composite material containing 80wt% PTFE maintained a superhydrophobic or water-repellent property with a water contact angle >150, although the Cu/WO3 in the composite material remained hydrophilic under visible light. The Cu/WO3-added PTFE particulate composite displayed photo-catalytic reactions to decompose oleic acid adsorbed on its surface and gaseous acetaldehyde under UV-A and visible-light illumination. All results demonstrate that the Cu/WO3-added PTFE particulate composite material may be used in sterilization, as a water repellent, for self-cleaning, and in the oxidative decomposition of volatile organic compounds (VOC) both indoors and outdoors.
Antibacterial Activity of Hydrophobic Composite Materials Containing a Visible-Light-Sensitive Photocatalyst
Kentaro Yamauchi,Yanyan Yao,Tsuyoshi Ochiai,Munetoshi Sakai,Yoshinobu Kubota,Goro Yamauchi
Journal of Nanotechnology , 2011, DOI: 10.1155/2011/380979
Abstract: The conventional superhydrophobic surface offered by PTFE provides no sterilization performance and is not sufficiently repellent against organic liquids. These limit PTFE's application in the field of disinfection and result a lack of durability. N-doped TiO2 photocatalyst added PTFE composite material was developed to remedy these shortcomings. This paper reports the surface characteristics, and the bactericidal and self-cleaning performance of the newly-developed composite material. The material exhibited a contact angle exceeding 150 degrees consistent with its hydrophobicity despite the inclusion of the hydrophilic N-doped TiO2. The surface free energy obtained for this composite was 5.8?mN/m. Even when exposed to a weak fluorescent light intensity (100 lx) for 24 hours, the viable cells of gram-negative E. coli on the 12% N-doped TiO2-PTFE film were reduced 5 logs. The higher bactericidal activity was also confirmed on the gram-positive MRSA. Compared with the N-doped TiO2 coating only, the inactivation rate of the composite material was significantly enhanced. Utilizing the N-doped TiO2 with the PTFE composite coating could successfully remove, by UV illumination, oleic acid adsorbed on its surface. These results demonstrate the potential applicability of the novel N-doped TiO2 photocatalyst hydrophobic composite material for both indoor antibacterial action and outdoor contamination prevention. 1. Introduction It is well known that the conventional superhydrophobic surface offered by polytetrafluoroethylene (PTFE) provides no sterilization performance and is not sufficiently repellent against organic matters. Thus, there is potential risk for bacteria to adhere to its surface more readily in ambient air, as well as organic matters is considered to reduce the durability of the superhydrophobic performance. To remedy this shortcoming, anatase titanium dioxide (TiO2), a UV light-sensitive photocatalyst added water repellent composite material has been developed in our previous study [1–5]. TiO2 was used to demonstrate the inactivation of various bacteria, such as Escherichia coli (E. coli), methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa (P. aeruginosa), Legionella pneumophila (L. pneumophila) [6–8], and Clostridium difficile spores [8]. The inclusion of TiO2 to the PTFE coating is expected to generate antimicrobial and self-cleaning properties, which would expand its scope of application. Anatase TiO2-added PTFE composite material is not only water-repellent but also exhibits self-cleaning properties. However, because
Excessive Base Money and Global Financial Crisis in Relation to the Essence of the So-Called “Abenomics”  [PDF]
Goro Takahashi
Journal of Financial Risk Management (JFRM) , 2013, DOI: 10.4236/jfrm.2013.24013
Abstract: After the financial crisis of 2008, we are facing possibility of a global financial crisis further. Most of the financial crises have occurred in situations when there is so much money in the financial market, but they have not often occurred in cases when the market does not have enough money. This thought, however, is not general common sense in the financial academic field. Based on general understanding, the cause of financial crisis is the lack of money with the rise of interest rates in the financial market. If the lack of money is the reason for financial crisis, then we have never met with any financial crisis, because most leading countries have much money in the financial market in nowadays. According to theory of Economics, government deficit plus current account surplus means surplus of savings in the private sector of the country. Currently, most countries with big-scale economy have big deficits in their national accounts. But there is enough money in the business sector. I focus on this aspect and then analyze the base money policy of the central bank of some countries, and analyze its effect or the meaning of excessive base money in the financial market. As a general economic rule, the excess of money in a financial market causes a low interest rate. On the other hand, governments are faced with less money. If enough money in the money market flows to the treasury account, the government gets national fiscal balance. But it is not easy for most governments to create the balance. The reason behind this is the failure of a national economic and fiscal policy, including tax policy. Many countries and communities are facing problems with the flow of money from the private sector to the government. This problem is one of the biggest international issues which should be solved immediately (Taylor, 2009). Of course, we cannot neglect the fact that there are countries having little money even their private sector like Greece, Italy, Spain, and so on. Economic growth is the only measure to solve the financial problem in these countries. I do not consider these countries in this paper. The financial markets that I focus on in this paper are the US, the EURO Area, China and Japan. Many experts and economic politician worldwide consider “Abenomics” noteworthy. It aims at increasing base money in the financial market of Japan. The biggest purpose of this policy is for breaking away from deflation. Japanese Prime minister Abe also expects devaluation of the Yen, and increase in Japanese export. Later in this paper, we will see that the amount of
Two Main Conditions for Collapse of the Bubble Economy of China—Large Number of Unsold Houses and Deregulation of Deposit Interest Rates  [PDF]
Goro Takahashi
Journal of Financial Risk Management (JFRM) , 2015, DOI: 10.4236/jfrm.2015.41005
Abstract: There are two kinds of asset bubble in China, and they are formed through these two assets, real estate assets and financial assets. Most studies looking into China’s economy said that the Chinese bubble will collapse soon. Majority of these studies, however, provide unclear reasons. In addition, they emphasize mostly on the bubble as the reason of the predicted collapse. Data gathered through fieldwork concerning real estate developers, non-banking companies, normal banks, local governments, and various housing construction sites in three cities of China and through analyses of literature, this paper studied two kinds of asset bubbles which are developing in China. And this research done through the fieldwork is insisted on that the bubble economy of China will not collapse easily. But when some conditions occur, the bubble economy will collapse. One of the conditions of the collapse is the number of unsold houses keeps increasing further. Many developers are facing financing problems. If the number of bankrupt developers increases, the bubble will collapse. Another important condition is that the deregulation of the deposit interest rate by PCB. Therefore, the most important thing is the authorities involved must strengthen the management ability of developers. In addition, the policy measure used to mitigate the deposit interest rates policy and its impact.
Convergence of functionals and its applications to parabolic equations
Goro Akagi
Abstract and Applied Analysis , 2004, DOI: 10.1155/s1085337504403030
Abstract: Asymptotic behavior of solutions of some parabolic equation associated with the p-Laplacian as p→
Global attractors for doubly nonlinear evolution equations with non-monotone perturbations
Goro Akagi
Mathematics , 2008,
Abstract: This paper proposes an abstract theory concerned with dynamical systems generated by doubly nonlinear evolution equations governed by subdifferential operators with non-monotone perturbations in a reflexive Banach space setting. In order to construct global attractors, an approach based on the notion of generalized semiflow is employed instead of the usual semi-group approach, since solutions of the Cauchy problem for the equation might not be unique. Moreover, the preceding abstract theory is applied to a generalized Allen-Cahn equation whose potential is divided into a convex part and a non-convex part as well as a semilinear parabolic equation with a nonlinear term involving gradients.
Stability of non-isolated asymptotic profiles for fast diffusion
Goro Akagi
Mathematics , 2015,
Abstract: The stability of asymptotic profiles of solutions to the Cauchy-Dirichlet problem for Fast Diffusion Equation (FDE, for short) is discussed. The main result of the present paper is the stability of any asymptotic profiles of least energy. It is noteworthy that this result can cover non-isolated profiles, e.g., those for thin annular domain cases. The method of proof is based on the Lojasiewicz-Simon inequality, which is usually used to prove the convergence of solutions to prescribed limits, as well as a uniform extinction estimate for solutions to FDE. Besides, local minimizers of an energy functional associated with this issue are characterized. Furthermore, the instability of positive radial asymptotic profiles in thin annular domains is also proved by applying the Lojasiewicz-Simon inequality in a different way.
A Re-Examination of the History of Etiologic Confusion between Dengue and Chikungunya
Goro Kuno
PLOS Neglected Tropical Diseases , 2015, DOI: 10.1371/journal.pntd.0004101
Abstract: Contrary to the perception of many researchers that the recent invasion of chikungunya (CHIK) in the Western Hemisphere marked the first episode in history, a recent publication reminded them that CHIK had prevailed in the West Indies and southern regions of the United States from 1827–1828 under the guise of “dengue” (DEN), and that many old outbreaks of so-called “dengue” actually represented the CHIK cases erroneously identified as “dengue.” In hindsight, this confusion was unavoidable, given that the syndromes of the two diseases—transmitted by the same mosquito vector in urban areas—are very similar, and that specific laboratory-based diagnostic techniques for these diseases did not exist prior to 1940. While past reviewers reclassified problematic “dengue” outbreaks as CHIK, primarily based on manifestation of arthralgia as a marker of CHIK, they neither identified the root cause of the alleged misdiagnosis nor did they elaborate on the negative consequences derived from it. This article presents a reconstructed history of the genesis of the clinical definition of dengue by emphasizing problems with the definition, subsequent confusion with CHIK, and the ways in which physicians dealt with the variation in dengue-like (“dengue”) syndromes. Then, the article identifies in those records several factors complicating reclassification, based on current practice and standards. These factors include terms used for characterizing joint problems, style of documenting outbreak data, frequency of manifestation of arthralgia, possible involvement of more than one agent, and occurrence of the principal vector. The analysis of those factors reveals that while some of the old “dengue” outbreaks, including the 1827–1828 outbreaks in the Americas, are compatible with CHIK, similar reclassification of other “dengue” outbreaks to CHIK is difficult because of a combination of the absence of pathognomonic syndrome in these diseases and conflicting background information.
Climate-Driven Changes in Lake Areas for the Last Half Century in the Valley of Lakes, Govi Region, Southern Mongolia  [PDF]
Alexander Orkhonselenge, Goro Komatsu, Munkhjargal Uuganzaya
Natural Science (NS) , 2018, DOI: 10.4236/ns.2018.107027
Abstract: This study presents the changes in lake areas in the Valley of Lakes, the Govi region, southern Mongolia. The recent changes in lake areas show decreases depending on vulnerability of lake basins and response of Govi landscape to the present climatic warming. During the recent 44 - 45 years (from 1970 to 2014 or 2015), modern lakes have encountered the present rapid increase in temperature, water evaporation and drying up that induced the reduction in lake areas in the Valley of Lakes. The finding of the reduction in lake areas is consistent with the trends on increasing in temperature since 1995 and fluctuating precipitation since 1975. Investigations with detailed chronology of lake sediment are needed from the lakes to review a more complete evolution of lake basins during the Late Quaternary paleoclimatic history in Mongolia and Central Asia.
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