C. E. Okafor, Alex Dubem Tagbo, O. Obiafudo, E. Nwadike
Aims: To select appropriate material and undertake fluid flow analysis of parallel flow heat exchanger. Methodology: Dynamic simulation study was performed to evaluate conditions of heat transfer of water through heat exchanger using ASPEN HYSYS. Cambridge Education Selector (CES) Granta software was used to select the suitable candidate materials for the heat exchanger. The properties of the selected materials and fluid characteristics were implemented in Computational Fluid Dynamics (CFD) to solve and analyze the fluid flow. Results: For inner pipe, low alloy steel having maximum thermal conductivity of 55(W/m°C) and specific heat capacity of 530 (J/kg°C) respectively was selected and used. For the outer pipe, cast iron, gray having thermal conductivity of 72 (W/m°C) and specific heat capacity of 495(J/kg°C) passed the selection criteria and was used.The total heat transfer surface area and hydraulic diameter was determined as 0.1341634m2 and 0.481m respectively while the velocity of flow (V) for hot and cold fluid was established as 0.00014518 m/sec and 0.000196817 m/sec respectively. Conclusion: The material-process decision on a parallel flow heat exchanger design was reduced to trade-off between performance and cost. The data obtained from the experimental record are well matched with computational fluid dynamics simulated values at different mass flow rate.
{"title":"Material Selection and Fluid Flow Analysis of Parallel Flow Heat Exchanger","authors":"C. E. Okafor, Alex Dubem Tagbo, O. Obiafudo, E. Nwadike","doi":"10.9734/acri/2016/30239","DOIUrl":"https://doi.org/10.9734/acri/2016/30239","url":null,"abstract":"Aims: To select appropriate material and undertake fluid flow analysis of parallel flow heat exchanger. \u0000Methodology: Dynamic simulation study was performed to evaluate conditions of heat transfer of water through heat exchanger using ASPEN HYSYS. Cambridge Education Selector (CES) Granta software was used to select the suitable candidate materials for the heat exchanger. The properties of the selected materials and fluid characteristics were implemented in Computational Fluid Dynamics (CFD) to solve and analyze the fluid flow. \u0000Results: For inner pipe, low alloy steel having maximum thermal conductivity of 55(W/m°C) and specific heat capacity of 530 (J/kg°C) respectively was selected and used. For the outer pipe, cast iron, gray having thermal conductivity of 72 (W/m°C) and specific heat capacity of 495(J/kg°C) passed the selection criteria and was used.The total heat transfer surface area and hydraulic diameter was determined as 0.1341634m2 and 0.481m respectively while the velocity of flow (V) for hot and cold fluid was established as 0.00014518 m/sec and 0.000196817 m/sec respectively. \u0000Conclusion: The material-process decision on a parallel flow heat exchanger design was reduced to trade-off between performance and cost. The data obtained from the experimental record are well matched with computational fluid dynamics simulated values at different mass flow rate.","PeriodicalId":421505,"journal":{"name":"EngRN: Chemical Engineering","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126348773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qiang Sun, C. Shu, Chengze Wang, Mengying Shi, Jiajia Xu, Qiaojie Luo, Mengjie Wu, Yadong Chen, Xiaodong Li
Aim: The aim of this study was to investigate the bonding effectiveness of the universal adhesive on caries-affected dentin and normal dentin of deciduous teeth.
Methods Extracted twelve second deciduous molars with one adjacent surface carious were collected. The half teeth with caries adjacent surface were grouped into the caries-affected group (Group test), while the caries-free half were grouped into the control group (Group control). For the Group test, carious tissue was removed with slow speed ball drill under the indication of caries maker.For the Group control, at the other side of the occlusal surface sound dentin was prepared to the similar deep level. Single bond Universal adhesive system using self-etch strategies was applied following the manufacturer's instructions.The defective part was filled with Shofu Beautifil II Namer, a commonly used resin composite in pediatric dentistry. Vertical sticks were obtained and subjected to tensile stress test. The morphology of the bonding surfaces were observed by scanning electron microscope and transmission electron microscopy.
Results: Electron microscope observation showed that there was no significant difference in morphology between caries-affected dentin and normal dentin. The minerals and smear layer were removed after acid etching, and the collagen network of dentin tubules and inter tubular dentin was exposed. There was no significant difference in the micro-tensile strengths between Group test and Group control (P > 0.05). Conclusion In vitro, caries-affected deciduous tooth dentin could achieve similar bonding strength to normal tooth dentin when Single Bond Universal adhesive was applied.
目的:研究通用胶粘剂对乳牙患龋牙本质与正常牙本质的粘接效果。方法收集12颗第二颗乳牙，1颗相邻面龋。将近面有龋的半颗牙分为患龋组(组试验)，无龋的半颗牙分为对照组(组对照组)。组试验在造龋机指示下，用慢速球钻去除龋组织。对照组在咬合面另一侧预备相同深度的健全牙本质。使用自蚀刻策略的单键通用粘合剂系统按照制造商的说明进行应用。缺陷部分用Shofu Beautifil II Namer填充，这是一种儿科牙科常用的树脂复合材料。获得垂直棒材并进行拉伸应力试验。用扫描电镜和透射电镜观察了键合表面的形貌。结果:电镜观察龋病牙本质与正常牙本质形态无明显差异。酸蚀后去除矿物质和涂抹层，暴露牙本质小管和管间牙本质的胶原网络。实验组与对照组的微拉伸强度无显著差异(P >0.05)。结论应用单键万能粘接剂对患龋乳牙牙本质的粘接强度可达到正常牙本质的水平。
{"title":"Bonding Effectiveness Study of the Universal Adhesive on Caries-Affected Dentin of Deciduous Teeth","authors":"Qiang Sun, C. Shu, Chengze Wang, Mengying Shi, Jiajia Xu, Qiaojie Luo, Mengjie Wu, Yadong Chen, Xiaodong Li","doi":"10.2139/ssrn.3673614","DOIUrl":"https://doi.org/10.2139/ssrn.3673614","url":null,"abstract":"Aim: The aim of this study was to investigate the bonding effectiveness of the universal adhesive on caries-affected dentin and normal dentin of deciduous teeth. <br><br>Methods Extracted twelve second deciduous molars with one adjacent surface carious were collected. The half teeth with caries adjacent surface were grouped into the caries-affected group (Group test), while the caries-free half were grouped into the control group (Group control). For the Group test, carious tissue was removed with slow speed ball drill under the indication of caries maker.For the Group control, at the other side of the occlusal surface sound dentin was prepared to the similar deep level. Single bond Universal adhesive system using self-etch strategies was applied following the manufacturer's instructions.The defective part was filled with Shofu Beautifil II Namer, a commonly used resin composite in pediatric dentistry. Vertical sticks were obtained and subjected to tensile stress test. The morphology of the bonding surfaces were observed by scanning electron microscope and transmission electron microscopy.<br><br>Results: Electron microscope observation showed that there was no significant difference in morphology between caries-affected dentin and normal dentin. The minerals and smear layer were removed after acid etching, and the collagen network of dentin tubules and inter tubular dentin was exposed. There was no significant difference in the micro-tensile strengths between Group test and Group control (P > 0.05). Conclusion In vitro, caries-affected deciduous tooth dentin could achieve similar bonding strength to normal tooth dentin when Single Bond Universal adhesive was applied.","PeriodicalId":421505,"journal":{"name":"EngRN: Chemical Engineering","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129841728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The structural stability of CeFe12 is investigated by using first-principles calculation. The formation energies of CeFe12 relative to the Ce2Fe17 + Fe phase and to the CeFe2 + Fe phase are calculated with the assumptions of trivalency and tetravalency for Ce. We compare them with corresponding results for Nd, Sm, and Zr. Our results suggest that the tetravalent Ce is a promising stabilizer of the ThMn12 structure. We also show that the stabilizing effect depends as much on the valency as on the size of R (rare-earth) element by investigating RFe12 where R is assumed to have a hypothetical valency.
{"title":"Cerium as a Possible Stabilizer of ThMn 12-Type Iron-Based Compounds: A First-Principles Study","authors":"Y. Harashima, T. Fukazawa, T. Miyake","doi":"10.2139/ssrn.3446974","DOIUrl":"https://doi.org/10.2139/ssrn.3446974","url":null,"abstract":"The structural stability of CeFe<sub>12</sub> is investigated by using first-principles calculation. The formation energies of CeFe<sub>12</sub> relative to the Ce<sub>2</sub>Fe<sub>17</sub> + Fe phase and to the CeFe<sub>2</sub> + Fe phase are calculated with the assumptions of trivalency and tetravalency for Ce. We compare them with corresponding results for Nd, Sm, and Zr. Our results suggest that the tetravalent Ce is a promising stabilizer of the ThMn<sub>12</sub> structure. We also show that the stabilizing effect depends as much on the valency as on the size of R (rare-earth) element by investigating RFe<sub>12</sub> where R is assumed to have a hypothetical valency.","PeriodicalId":421505,"journal":{"name":"EngRN: Chemical Engineering","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126851833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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