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High strain-to-failure porous alumina ceramics with improved mechanical properties
D. Doni Jayaseelan,S. Ueno,T. Ohji,S. Kanzaki 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.1
A pulse electric current sintering technique was employed to fabricate porous alumina from a commercially available powder. Porosity was controllable between 20 to 50% depending on the sintering temperature. The fracture strength was correlated exponentially as a function of porosity. A high strength of ~250 MPa was achieved for the specimens, which had porosity of 30 vol.%. The strain-to-failure of the porous Al2O3 ceramics increased considerably and this improves the reliability of the specimens.
Increase of Cardiometabolic Biomarkers Among Vehicle Inspectors Exposed to PM0.25 and Compositions
Ramdhan, Doni Hikmat,Kurniasari, Fitri,Tejamaya, Mila,Fitri, Aidila,Indriani, Aisyah,Kusumawardhani, Adinda,Santoso, Muhayatun Occupational Safety and Health Research Institute 2021 Safety and health at work Vol.12 No.1
Background: Exposure to particulate matter (PM) emitted from vehicle exhaust might disrupt systemic function and elevate the risk of cardiovascular disease. In this study, we examined the changes of cardiometabolic biomarkers among vehicle inspectors exposed daily to PM0.25 and components. Methods: This cross-sectional study was conducted at two vehicle inspection centers, Pulogadung and Ujung Menteng, located in East Jakarta, Indonesia. The exposed respondents were 43 workers from vehicle inspection centers, and the unexposed group consisted of 22 staff officers working in the same locations. Vehicle exhaust particulate matter was measured for eight hours using a Leland Legacy personal pump attached to a Sioutas Cascade Impactor. The used filters were 25 and 37-mm quartz filters. The particulate matter concentration was analyzed using a gravimetric method, whereas trace elements were analyzed using energy dispersive X-ray fluorescence. An EEL Smoke Stain Reflectometer analyzed black carbon. Results: The personal exposure concentrations of PM0.25 were 10.4-fold higher than those in unexposed groups. Calcium and sulfur were the major components in the obtained dust, and their levels were 3.3- and 7.2-fold higher, respectively, in the exposed group. Based on an independent-samples t-test, high-density lipoprotein, triglyceride, HbA1c, total immunoglobulin E, high-sensitivity C-reactive protein, tumor necrosis factor-alpha, and nitric oxide levels were significantly different between the groups. Conclusions: In summary, it was suggested that PM0.25 exposure from vehicle exhaust might affect cardiometabolic biomarkers change.
Iryanti Fatyasari Nata,Doni Rahmat Wicakso,Agus Mirwan,Chairul Irawan,Rinna Juwita,Niken Anggraini Astuti,Rizka Tiara An-Nisa 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.7
Rice husk (RH) cellulose as a matrix was synthesized for amine rice husk magnetic biocomposite (RBNH2)by one-pot solvothermal method. The synergic effect of amine on magnetic nanoparticle will enhance the reactivityof material. Ethylene glycol as solvent was used for dissolved iron(III) chloride hexahydrate, Na-acetate anhydrate,and 1,6-hexanediamine, then RH was added, kept at ±200 oC for 6 h. The optimums of Fe contained and amineconcentrations on biocomposite were detected at 93% and 2.9mmol/g, respectively. The surface area of rice husk significantlyincreased from 1.309m2 g1 to 19.45m2 g1 when converted to biocomposite. The RB-NH2 has good capabilityto adsorb Cu(II) ion at 116.45mg g1 at pH 5 for 60min. Surprisingly, during adsorption, the RB-NH2 also workedon reducing the chemical oxygen demand (COD) number, total suspended solid (TSS) and dye for 22%, 54.37%, and33.74%, respectively. The reuse effectiveness for RB-NH2 showed a good result with four repetitions. The multipleeffects of amine rice husk magnetic biocomposite on wastewater contaminants leads to becoming a candidate materialto be developed and applied in a wide range of waste water treatment applications.
Shunkichi Ueno,D. Doni Jayaseelan,Tatsuki Ohji,Hua-Tay Lin 한양대학교 세라믹연구소 2005 Journal of Ceramic Processing Research Vol.6 No.1
The oxidation and water vapor corrosion behavior of sintered HfSiO4, ZrSiO4, TiSiO4 compacts and high density HfSiO4 coated silicon nitride ceramics were examined at 1500 oC in a static state water vapor environment. The bulk weights of HfSiO4 and ZrSiO4 decreased after the water vapor corrosion test with a weight loss rate of 7.080 × 10−6 and 1.333 × 10−6 g/cm2·h, respectively. The weight of TiSiO4 remained unchanged within the experimental error after the corrosion test. A trace of corrosion was observed on the surface of grains of corrosion-tested compacts. On the other hand, the weight of high density HfSiO4 layer (Environmental Barrier Coating, EBC layer) coated silicon nitride specimens increased with a weight gain rate 1.495 × 10−6 g/cm2·h, which is attributed by the oxidation of the silicon nitride substrate.
Comparison of water vapor corrosion mechanisms of polycrystalline and eutectic Lu2Si2O7
Shunkichi Ueno,D. Doni Jayaseelan,Tatsuki Ohji,Naoki Kondo,Shuzo Kanzaki 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.2
To clarify the water vapor corrosion mechanism of the Lu2Si2O7 system, a high temperature water vapor corrosion test was performed on two microstructurally different specimens namely, polycrystalline and eutectic. From the results, we address the problem of the application of the Lu2Si2O7 system for environmental barrier coatings (EBC) with regard to their microstructure. In the case of the polycrystalline sample, the boundaries were easily corroded and the silicon nitride substrate underwent oxidation. In the case of the eutectic sample, no weight change was observed during the corrosion test. However, a trace of corrosion and poly-crystallization was observed on the sample surface. An easy processing technique for forming an eutectic protective layer on silicon nitride ceramics is also proposed.
Comparison of water vapor corrosion behavior of silicon nitride with various EBC layers
Shunkichi Ueno,D. Doni Jayaseelan,Tatsuki Ohji 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.4
The water vapor corrosion resistance of silicon nitride ceramics with Lu2Si2O7, Yb2Si2O7 and ZrSiO4 environmental barrier coating (EBC) layers prepared by a reaction sintering method were examined at 1500 oC in a static state water vapor environment. The weights of these samples slightly increased during the corrosion test. The weight gain rates for Lu, Yb and zircon EBC samples were 2.218 × 10−6, 4.688 × 10−6 and 2.989 × 10−6 g/cm2·h, respectively. In the corrosion mechanism of Lu and Yb cases, the gas path through channels in the EBC layer were generated by the elimination of the boundary silica phase and then, the silicon nitride substrate was slightly oxidized. On the other hand, in the case of ZrSiO4, many cracks were introduced in the EBC layer during the corrosion test due to the difference in thermal expansion coefficient between the EBC layer and the substrate. However, the adhesion between the substrate and the EBC layer of ZrSiO4 was better than that of Lu and/or Yb EBC samples.
THE EFFECT OF TELEVISION-VIEWING MOTIVATION AND INDIVIDUAL TRAITS ON ZAPPING BEHAVIOR
Mingqi Ye,Wirawan Dony Dahana,Chris Baumann,Sotaro Katsumata 글로벌지식마케팅경영학회 2023 Global Marketing Conference Vol.2023 No.07
This study investigates how zapping behavior is affected by television-viewing motives, classified into two broad categories: goal-directed instrumental motives and process-oriented ritualistic motives. We examine how such an impact varies among individuals with different degrees of advertising skepticism, opinion leadership, ongoing search, program involvement, and advertising involvement. By combining the television-viewing information of 1,162 individuals from April 2017 to March 2018 with survey data, we empirically analyze the effect of motivation on viewers’ zapping likelihood. The results suggest that zapping probability is lower when television-viewing is driven by instrumental motives than by ritualistic motives. The negative impact of instrumental motivations is more evident for individuals with higher ongoing search tendencies. By contrast, individuals who are more skeptical toward advertisements, have higher opinion leadership, or have higher program involvement are less vulnerable to such viewing motivations. We discuss the implications of these findings for devising an effective advertisement placement strategy.
Salma Chaush,Nazim Husain,Mohd Khalid,Meenu Doni,Mohd Qudrathullah Khan,Md Majid Hussain 경희대학교 융합한의과학연구소 2023 Oriental Pharmacy and Experimental Medicine Vol.23 No.2
Hemorrhoidal disease is one of the most common gastrointestinal ailments affecting life quality of the patients. Unani classical literature is replete with anti-hemorrhoidal drugs, but scientific evidence is lacking. Therefore, Safūf Zāj (powdered alum) and Marham-e-Māzū (gall ointment) having potent anti-hemorrhoidal actions were selected to evaluate their efficacy in hemorrhoids. This clinical trial was conducted on 30 participants with hemorrhoids, aged > 18 years. All the participants received Safūf Zāj for sitz baths and Marham-e-Māzū to be applied twice daily for 2 weeks. Primary outcome measures were: change in pain intensity, anal itching, and defecate discomfort assessed on 100 mm VAS scale and per-rectal bleeding assessed on 4-point scale. Secondary outcome measures were: change in the size of the external hemorrhoidal mass assessed on 5-point scale, grade of internal hemorrhoid assessed by Goligher classification and quality of life (QoL) assessed on SF-12 questionnaire. The per-protocol analysis was done on 30 participants and statistically significant improvement was seen in primary and secondary outcome measures. Moreover, both the mental and psychological components of QoL were improved. The study inferred that therapeutic approach of Safūf Zāj and Marham-e-Mazu is safe and efficacious in hemorrhoids. Future studies with well-designed RCTs are highly recommended.