Synthesis of nano-sized Ag metal particles protected by adsorbed 3-mercapto-propionic acid

Hiromi Yamashita,Masanori Tomonari,Hitomi Sadohara,Tetsu Yonezawa,Kohsuke Mori 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.3

Nano-sized Ag metal particles can be synthesized by the addition of sodium borohydride as a reducing agent into an aqueous solution of AgNO3 mixed with 3-mercapto-propionic acid as a protective agent. Using this method the synthesis of an aqueous Ag colloid system with a high density became possible, because the surfaces of synthesized nano-sized Ag metal particles were covered and protected by the adsorbed 3-mercapto-propionic acid. The strong electrostatic repulsion of the negative charge of the carboxylate anion of the adsorbed 3-mercapto-propionic acid disturbed the aggregation of metal particles in the solution with a high pH value (pH > 5), but the aggregation occurred in a solution of low pH value (pH < 2) because of the neutral surface of particles. Using simple coating and baking processes with this aqueous Ag colloid system, an Ag membrane can be formed on glass plate by the partial welding between the nano-size Ag particles. This Ag membrane exhibited a very low electrical resistivity even after baking at a low temperature such as 423 K. Nano-sized Ag metal particles can be synthesized by the addition of sodium borohydride as a reducing agent into an aqueous solution of AgNO3 mixed with 3-mercapto-propionic acid as a protective agent. Using this method the synthesis of an aqueous Ag colloid system with a high density became possible, because the surfaces of synthesized nano-sized Ag metal particles were covered and protected by the adsorbed 3-mercapto-propionic acid. The strong electrostatic repulsion of the negative charge of the carboxylate anion of the adsorbed 3-mercapto-propionic acid disturbed the aggregation of metal particles in the solution with a high pH value (pH > 5), but the aggregation occurred in a solution of low pH value (pH < 2) because of the neutral surface of particles. Using simple coating and baking processes with this aqueous Ag colloid system, an Ag membrane can be formed on glass plate by the partial welding between the nano-size Ag particles. This Ag membrane exhibited a very low electrical resistivity even after baking at a low temperature such as 423 K.

Age Differences in Naloxone Reversibility of Electroacupuncture on the Jaw Opening Reflex in Rats

Hiromi Yamashita,Jorge Luis Lopes Zeredo,Kazuo Toda 사단법인약침학회 2021 Journal of Acupuncture & Meridian Studies Vol.14 No.4

Background: Electroacupuncture is one of the most popular physical treatments for clinical pain, but the potential influence of a patient’s age on the effectiveness of electro acupuncture treatment has not been clearly established. Objectives: The present study aimed to detect a potential difference in electroacu puncture-induced analgesia between juvenile and adult rats. Methods: In this study, we investigated the effects of electroacupuncture treatment on the nociceptive jaw-opening reflex evoked by tooth-pulp stimulation in juvenile and adult rats. Results: Our results showed there were age differences in electroacupuncture-induced analgesic effects in rats, especially with naloxone antagonization. The ratio of naloxonereversibility against electroacupuncture analgesia was greater in adult rats than in juvenile rats. Conclusion: These results suggest that electroacupuncture analgesia is produced mainly by the non-opioid system in juvenile rats and by the opioid system in adult rats.

CHARACTERIZATION OF Ti/Si BINARY OXIDES PREPARED BY THE SOL - GEL METHOD AND THEIR PHOTOCATALYTIC PROPERTIES : THE HYDROGENATION AND HYDROGENOLYSIS OF CH3CCH WITH H₂O

Yamashita, Hiromi,Kawasaki, Shinichi,Ichihashi, Yuichi,Takeuchi, Masato,Harada, Masaru,Anpo, Masakazu,Louis, Catherine,Che, Michel 한국화학공학회 1998 Korean Journal of Chemical Engineering Vol.15 No.5

Titanium-silicon (Ti/Si) binary oxides having different Ti content were prepared by the sol-gel method and utilized as photocatalysts for the hydrogenation and hydrogenolysis of CH₃CCH with H₂O. The photocatalytic reactivity and selectivity of these catalysts were investigated as a function of the Ti content and it was found that the hydrogenolysis reaction (C₂H_6 formation) was predominant in regions of low Ti content, while the hydrogenation reaction (C₃H_6 formation) proceeded in regions of high Ti content. The in situ photoluminescence, diffuse reflectance absorption, FT-IR, XAFS (XANES and EXAFS), and XPS spectroscopic investigations of these Ti/Si binary oxides indicated that the titanium oxide species are highly dispersed in the SiO₂ matrices and exist in a tetrahedral coordination exhibiting a characteristic photoluminescence spectrum. The charge transfer excited state of the tetrahedrally coordinated titanium oxide species plays a significant role in the efficient photoreaction with a high selectivity for the hydrogenolysis of CH₃CCH to producea mainly C₂H_6, and CH₄, while the catalysts involving the aggregated octahedrally coordinated titanium oxide species show a high selectivity for the hydrogenation of CH₃CCH to produce C₃H_6, being similar to reactions of the powdered TiO₂ catalysts. The good parallel relationship between the yield of the photolumunescence and the specific photocatalytic reactivity of the Ti/Si binary oxides as a function of the Ti content clearly indicates that the high phatocatalytic reactivity of the Ti/Si binary oxides having low Ti content is associated with the high reactivity of the charge transfer excited state, of the isolated titanium oxide species in tetrahedral coordination, [Ti^(3+)-O^-]^*.

DQRUMA / PAR Method for Multimedia Wireless Access Networks

Tetsuya Yamashita,Takashi Matsumoto,Tomohiro Haruki,Hiromi Okada 대한전자공학회 1998 대한전자공학회 심포지엄 논문집 Vol.3 No.-

Photocatalytic Epoxidation of Olefins Using Molecular O₂ by TiO₂ Incorporated in Hydrophobic Y Zeolite

Kuwahara, Yasutaka,Magatani, Yasuhiro,Yamashita, Hiromi Korean Society of Photoscience 2015 Rapid communication in photoscience Vol.4 No.1

Zeolite is an ideal host material for encapsulating nano-size metal catalyst species because of its defined microporous structure, prominent adsorption/condensation properties, high surface area, chemical/thermal stability, and transparency to light. In this study, $TiO_2$ photocatalyst was incorporated in highly hydrophobic Y zeolite and its photocatalytic activity was examined in the photocatalytic oxidation of olefins under UV-light irradiation using molecular oxygen as an oxygen source. $TiO_2$ nanoparticles incorporated in hydrophobic Y zeolite exhibited a markedly enhanced photocatalytic activity compared with bare $TiO_2$ owing to its excellent affinity toward organic moieties, which facilitates the mass transfer of organic substrates and allows them to efficiently access to the neighboring active $TiO_2$ surface.

Incidence of Nocturnal Leg Cramps in Patients with Lumbar Spinal Stenosis before and after Conservative and Surgical Treatment

Seiji Ohtori,Masaomi Yamashita,Yasuaki Murata,Yawara Eguchi,Yasuchika Aoki,Hiromi Ataka,Jiro Hirayama,Tomoyuki Ozawa,Tatsuo Morinaga,Hajime Arai,Masaya Mimura,Hiroto Kamoda,Sumihisa Orita,Masayuki Miy 연세대학교의과대학 2014 Yonsei medical journal Vol.55 No.3

Purpose: To examine the effects of conservative and surgical treatments for nocturnalleg cramps in patients with lumbar spinal stenosis (LSS). Nocturnal leg cramps is frequently observed in patients with peripheral neuropathy. However, there have been few reports on the relationship between nocturnal leg cramps and LSS, and it remains unknown whether conservative or surgical intervention has an impact on leg cramps in patients with LSS. Materials and Methods: The subjects were 130 LSS patients with low back and leg pain. Conservative treatment such as exercise, medication, and epidural block was used in 66 patients and surgical treatmentsuch as decompression or decompression and fusion was performed in 64 patients. Pain scores and frequency of nocturnal leg cramps were evaluated based on self-reported questionnaires completed before and 3 months after treatment. Results: The severity of low back and leg pain was higher and the incidence of nocturnal leg cramps was significantly higher before treatment in the surgically treated group compared with the conservatively treated group. Pain scores improvedin both groups after the intervention. The incidence of nocturnal leg cramps was significantly improved by surgical treatment (p=0.027), but not by conservative treatment (p=0.122). Conclusion: The findings of this prospective study indicate that the prevalence of nocturnal leg cramps is associated with LSS and severity of symptoms. Pain symptoms were improved by conservative or surgicaltreatment, but only surgery improved nocturnal leg cramps in patients with LSS. Thus, these results indicate that the prevalence of nocturnal leg cramps is associatedwith spinal nerve compression by LSS.

PREPARATION OF TRANSPARENT TS-1 ZEOLITE FILM AND ITS PHOTOCATALYTIC ISOMERIZATION UNDER UV IRRADIATION

Shul, Yong Gun,Yamashita, Hiromi,Anpo, Masakazu,Jung, Kyeong Taek 한국화학공학회 1997 Korean Journal of Chemical Engineering Vol.14 No.3

TS-1 zeolite film has been prepared by using nano sized TS-1 zeolite particles for the photocatalytic isomerization of cis-2-butene. TS-1 zeolite film showed optical transparent property and the thickness of film was 0.7 ㎛. UV irradiation of TS-1 zeolite film in the presence of cis-2-butene leads to the photocatalytic isomerization of cis-2-butene into trans-2-butene at the temperature of 275 K. The yield of trans-2-butene was linearly increased with UV-irradiation time.

Conservative and Surgical Treatment Improves Pain and Ankle-Brachial Index in Patients with Lumbar Spinal Stenosis

Seiji Ohtori,Masaomi Yamashita,Yasuaki Murata,Yawara Eguchi,Yasuchika Aoki,Hiromi Ataka,Jiro Hirayama,Tomoyuki Ozawa,Tatsuo Morinaga,Hajime Arai,Masaya Mimura,Hiroto Kamoda,Sumihisa Orita,Masayuki Miy 연세대학교의과대학 2013 Yonsei medical journal Vol.54 No.4

Purpose: The pathological mechanism of lumbar spinal stenosis is reduced blood flow in nerve roots and degeneration of nerve roots. Exercise and prostaglandin E1 is used for patients with peripheral arterial disease to increase capillary flow around the main artery and improve symptoms; however, the ankle-brachial index (ABI), an estimation of blood flow in the main artery in the leg, does not change after treatment. Lumbar spinal nerve roots contain somatosensory, somatomotor, and unmyelinated autonomic nerves. Improved blood flow by medication with prostaglandin E1 and decompression surgery in these spinal nerve roots may improve the function of nerve fibers innervating muscle, capillary, and main vessels in the lower leg, resulting in an increased ABI. The purpose of the study was to examine whether these treatments can improve ABI. Materials and Methods: One hundred and seven patients who received conservative treatment such as exercise and medication (n=56) or surgical treatment (n=51) were included. Low back pain and leg pain scores, walking distance, and ABI were measured before treatment and after 3 months of conservative treatment alone or surgical treatment followed by conservative treatment. Results: Low back pain, leg pain, and walking distance significantly improved after both treatments (p<0.05). ABI significantly increased in each group (p<0.05). Conclusion: This is the first investigation of changes in ABI after treatment in patients with lumbar spinal stenosis. Improvement of the spinal nerve roots by medication and decompression surgery may improve the supply of blood flow to the lower leg in patients with lumbar spinal stenosis.

Design and Development of Titanium and Vanadium Oxide Photocatalysts Incorporated within Zeolite Cavities and their Photocatalytic Reactivities

Shul, Yong Gun,Park, Sang Eon,Yamashita, Hiromi,Anpo, Masakazu,Matsuoka, Masaya,Park, Dal Ryung 한국공업화학회 2000 Journal of Industrial and Engineering Chemistry Vol.6 No.2

Titanium or vanadium oxide species incorporated within the framework of zeolites or mesoporous molecular sieves by an ion-exchange method or hydrothermal synthesis show high and unique photocatalytic activities for various reactions such as the decomposition of NO into O_2 or the reduction activities of CO_2 with H_2O to produce CH_4 and CH_3OH. In situ photoluminescence, XAFS and ESR investigations revealed that titanium as well as vanadium oxide moieties exist in highly dispersed tetrahedral coordination states in the zeolite framework and the charge transfer excited state of these transition metal oxide species play a vital role in the photocatalytic reactions on these zeolite and molecular sieve catalysts. The unique physicochemical properties of porous materials such as pore size, channel structural dimensions, and distribution of ion-exchangeable sites are shown to be important factors in controlling the dispersion and local structures of the metal oxides incorporated within such porous materials as well as the photocatalytic reactivities and selectivities in various photocatalytic reactions.

Photocatalytic Decomposition of NO on Transition Metal Ion-exchanged Zeolite Catalysts

Shul, Yong Gun,Park, Sang Eon,Yamashita, Hiromi,Anpo, Masakazu,Matsuoka, Masaya,Ju, Woo Sung 한국공업화학회 2000 Journal of Industrial and Engineering Chemistry Vol.6 No.3

Transition metal ions (Cu^+, Ag^+) incorporated within the cavities of zeolites by an ion-exchange method show an efficient and unique photocatalytic performance for the decomposition of NO into N₂ and O₂ at 275 K. In situ ESR, UV-VIS, photoluminescence and XAFS (XANES and FT-EXAFS) investigations revealed that the transition metal ions exist in highly dispersed state with linear 2 coordination sphere within the pores of zeolites, the local structures of the metal ions being significantly affected by changing the kinds of zeolites. Detailed studies of the interaction of NO with the excited states of these metal ions clearly indicated that unique inner shell type excitation states of these metal ions play a significant role in the photocatalytic decomposition of NO, i.e., an electron transfer from the s orbital of the excited state of Cu^+ or Ag^+ ions into the π^* antibonding orbital of NO initiates the decomposition reaction of NO.