• Title/Summary/Keyword: external acid sites

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Hyaluronic Acid Filler Injection Guided by Doppler Ultrasound

  • Won Lee
    • Archives of Plastic Surgery
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    • v.50 no.4
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    • pp.348-353
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    • 2023
  • Doppler ultrasound can be used to detect almost all arteries of the face before injecting the hyaluronic acid (HA) filler. The relatively more dangerous sites of filler injection are the glabellar wrinkle, forehead, temple, nose, and nasolabial fold area, and it is recommended to map the vasculature of these areas by Doppler ultrasound before performing filler injection. The Doppler ultrasound detection method is included as a video. Internal carotid arterial branches, the supratrochlear, supraorbital, and dorsal nasal arteries, and external carotid arterial branches, the superficial temporal and facial arteries, are very important arteries when injecting HA filler; thus, Doppler ultrasound detection is recommended.

Shape-Selective Catalysis over Zeolite. An Attempt in the Alkylation of Biphenyl

  • Sugi, Yoshihiro;Komura, Kenichi;Kim, Jong Ho
    • Applied Chemistry for Engineering
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    • v.17 no.3
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    • pp.235-242
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    • 2006
  • Liquid phase alkylation of biphenyl (BP) was studied over large pore zeolites. Selective formation of the least bulky products, 4,4'-diisopropylbiphenyl (4,4'-DIPB) occurred only in the isopropylation of BP over some large pore molecular sieves. H-mordenites (MOR) gave the highest selectivity among them. The dealumination of MOR enhanced catalytic activity and the selectivity of 4,4'-DIPB because of the decrease of coke-deposition. Non-selective catalysis occurs on external acid sites over MOR with the low $SiO_2/Al_2O_3$ ratio because severe coke-deposition deactivates the acid sites inside the pores by blocking pore openings. The selectivity of DIPB isomers was changed with reaction temperature. Selective formation of 4,4'-DIPB was observed at moderate temperatures such as $250^{\circ}C$, whereas the decrease of the selectivity of 4,4'-DIPB occurred at higher temperatures as $300^{\circ}C$. However, 4,4'-DIPB was almost exclusive isomer in the encapsulated DIPB isomers inside the pores even at high temperatures. These decreases of the selectivity of 4,4'-DIPB are due to the isomerization of 4,4'-DIPB on the external acid sites. Some 12-membered molecular sieves, such as SSZ-24, MAPO-5 (M:Mg, Zn, Si), SSZ-31, and ZSM-12, which have straight channels, gave 4,4'-DIPB with moderate to high selectivity; however; SSZ-55, SSZ-42, and MAPO-36 (M: Mg, Zn) gave lower selectivity because of cages in 12-membered one dimensional channels. Three dimensional H-Y and Beta zeolites also yield 4,4'-DIPB in low yield because of their wide circumstances for the isopropylation of BP. The increasing the size of alkylating agent enhanced the shape-selective alkylaiton even for the zeolites, such as UTD-1. The ethylation of BP to ethylbiphenyls (EBPs) and diethylbiphenyls (DEBPs) over MOR was non-selective. The ethylation of BP to EBPs was controlled kinetically. However, there was difference in reactivity of EBPs and DEBPs for their further ethylation. 4-EBP was ethylated preferentially among the isomers, although the formation of 4,4'-DEBP was less selective. The least bulky 4-EBP and 4,4'-DEBP have the highest reactivity among EBPs and DEBPs for the ethylation to polyethylbiphenyls (PEBPs). These results show that the environments of MOR pores are too loose for shape selective formation of the least bulky isomers, 4-EBP and 4,4'-DEBP in the ethylation of BP, and that MOR pores have enough space for the further ethylation of 4,4'-DEBP.

New insights about coke deposition in methanol-to-DME reaction over MOR-, MFI- and FER-type zeolites

  • Migliori, Massimo;Catizzone, Enrico;Aloise, Alfredo;Bonura, Giuseppe;Gomez-Hortiguela, Luis;Frusteri, Leone;Cannilla, Catia;Frusteri, Francesco;Giordano, Girolamo
    • Journal of Industrial and Engineering Chemistry
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    • v.68
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    • pp.196-208
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    • 2018
  • The effect of channel-system of zeolite on methanol-to-DME reaction was studied. Results revealed that channels size and topology affect catalyst lifetime, type and location of coke precursors. FER and MFI showed the best resistance towards coke deposition, whilst fast deactivation was observed on MOR. Although the higher concentration and strength of acid sites, FER structure formed a lower coke amount, preferably located within the pores, while coke cluster deposited on the external surface of MOR. Analysis of acid sites distribution and strength was performed during deactivation-regeneration process. Coke location assessment was also supported by molecular simulations.

Isoforms of Glucose 6-Phosphate Dehydrogenase in Deinococcus radiophilus

  • Sung, Ji-Youn;Lee, Young-Nam
    • Journal of Microbiology
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    • v.45 no.4
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    • pp.318-325
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    • 2007
  • Glucose 6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) in Deinococcus radiophilus, an extraordinarily UV-resistant bacterium, was investigated to gain insight into its resistance as it was shown to be involved in a scavenging system of superoxide $(O_2^{-1})$ and peroxide $(O_2^{-2})$ generated by UV and oxidative stresses. D. radiophilus possesses two G6PDH isoforms: G6PDH-1 and G6PDH-2, both showing dual coenzyme specificity for NAD and NADP. Both enzymes were detected throughout the growth phase; however, the substantial increase in G6PDH-1 observed at stationary phase or as the results of external oxidative stress indicates that this enzyme is inducible under stressful environmental conditions. The G6PDH-1 and G6PDH-2 were purified 122- and 44-fold (using NADP as cofactor), respectively. The purified G6PDH-1 and G6PDH-2 had the specific activity of 2,890 and 1,033 U/mg protein (using NADP as cofactor) and 3,078 and 1,076 U/mg protein (using NAD as cofactor), respectively. The isoforms also evidenced distinct structures; G6PDH-1 was a tetramer of 35 kDa subunits, whereas G6PDH-2 was a dimer of 60kDa subunits. The pIs of G6PDH-1 and G6PDH-2 were 6.4 and 5.7, respectively. Both G6PDH-1 and G6PDH-2 were inhibited by both ATP and oleic acid, but G6PDH-1 was found to be more susceptible to oleic acid than G6PDH-2. The profound inhibition of both enzymes by ${\beta}-naphthoquinone-4-sulfonic$ acid suggests the involvement of lysine at their active sites. $Cu^{2+}$ was a potent inhibitor to G6PDH-2, but a lesser degree to G6PDH-1. Both G6PDH-1 and G6PDH-2 showed an optimum activity at pH 8.0 and $30^{\circ}C$.

Dehydration of D-xylose over SAPO Catalysts Synthesized with Various Structure Directing Agents (다양한 구조 유도제로 합성된 SAPO촉매를 이용한 자일로오스의 탈수화반응)

  • Kim, Saet Byul;You, Su Jin;Kim, Yong Tae;Chae, Ho-Jeong;Jeong, Soon-Yong;Park, Eun Duck
    • Korean Chemical Engineering Research
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    • v.48 no.6
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    • pp.684-689
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    • 2010
  • We synthesized a variety of SAPO catalysts with various structure directing agents by the hydrothermal method and applied them to the D-xylose dehydration. Single or mixtures of organic amines, viz. tetraethylammonium hydroxide(TEAOH), dipropylamine(DPA), diethylamine(DEA), morpholine and diethanolamine(DEtA) were used as structure directing agents. The $N_2$-isotherm, $NH_3$-temperature programmed desorption(TPD) and temperature programmed oxidation(TPO) were conducted to characterize SAPO catalysts. Among tested SAPO catalysts, the SAPO-34 synthesized with morpholine showed the highest furfural yield. The external surface area as well as the surface concentration of acid sites appeared to affect the catalytic activity for the dehydration of xylose into furfural.

Clinical Characteristics of Trauma-Related Chronic Osteomyelitis in 3 Wild Raccoon Dogs (Nyctereutes procyonoides)

  • Ha, Minjong;Ahmed, Sohail;Lee, Do Na;Han, Janghee;Yoon, Junghee;Yeon, Seong-Chan
    • Journal of Veterinary Clinics
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    • v.39 no.3
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    • pp.131-137
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    • 2022
  • Osteomyelitis typically occurs because of the direct inoculation of bacteria or fungi after penetrating trauma or surgical contamination or, by extension, from soft tissue infection. Osteomyelitis is rarely reported in wildlife animals, though severe chronic osteomyelitis cases do exist in wildlife owing to the scarcity of medical support in the wild environment. This report describes three cases of chronic osteomyelitis in wild raccoon dogs related to trauma. The typical symptoms of three reported cases were ataxia, stiffness, muscle atrophy, and lethargy. All three cases were relevant to traumatic or severe external injury, and skin infestation caused by ectoparasites was apparent on an ocular inspection. In the radiographic examination, diffuse sites of osteolytic lesions and remarkable periosteal responses were demonstrated around the injured limb in all three cases. Apparent neutrophilia with a left shift, lymphocytosis, and monocytosis in hematological examinations generally indicated chronic infection as shown in case 1 and 3. Treatment was attempted with broad-spectrum antibiotics and non-steroidal anti-inflammatory drugs, such as amoxicillin/clavulanic acid, enrofloxacin, clindamycin, and meloxicam. These treatment options helped improve the overall prognosis of chronic osteomyelitis, but the outcomes did not meet the treatment goal entirely. Osteomyelitis can be extremely challenging to treat, particularly in wild animals, because of their distinctive traits, such as masking phenomenon and uncontrolled exposure to ectoparasites. Earlier diagnosis with a radiographic examination, hematological examinations, and careful patient monitoring, followed by prolonged antibiotic therapy and restricted exercise, are the key factors leading to a better prognosis.

A Study on Heterogeneous Catalysts for Transesterification of Nepalese Jatropha Oil (네팔산 Jatropha 오일의 전이에스테르화 반응용 불균일계 촉매 연구)

  • Youngbin Kim;Seunghee Lee;Minseok Sim;Yehee Kim;Rajendra Joshi;Jong-Ki Jeon
    • Clean Technology
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    • v.30 no.1
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    • pp.47-54
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    • 2024
  • Jatropha oil extracted from the seeds of Nepalese Jatropha curcas, a non-edible crop, was used as a raw material and converted to biodiesel through a two-step process consisting of an esterification reaction and a transesterification reaction. Amberlyst-15 catalyst was applied to the esterification reaction between the free fatty acids contained in the Jatropha oil and methanol. The acid value of the Jatropha oil could be lowered from 11.0 to 0.26 mgKOH/g through esterification. Biodiesel was synthesized through a transesterification reaction between Jatropha oil with an acid value of 0.26 mgKOH/g and methanol over NaOH/γ-Al2O3 catalysts. As the loading amount of NaOH increased from 3 to 25 wt%, the specific surface area decreased from 129 to 28 m2/g and the pore volume decreased from 0.249 to 0.129 cm3/g. The amount and intensity of base sites over the NaOH/γ-Al2O3 catalysts increased simultaneously with the NaOH loading amount. It was confirmed that the optimal NaOH loading amount for the NaOH/γ-Al2O3 catalyst was 12 wt%. The optimal temperature for the transesterification reaction of Jatropha oil using the NaOH/γ-Al2O3 catalyst was selected to be 65 ℃. In the transesterification reaction of Jatropha oil using the NaOH/γ-Al2O3 catalyst, the reaction rate was affected by external diffusion limitation when the stirring speed was below 150 RPM, however the external diffusion limitation was negligible at higher stirring speeds.