1,721,677 research outputs found
Shin, Ji Won
No full text학위논문(석사)--아주대학교 일반대학원 :약학과,2020. 21. Introduction 1
1.1 Phthalate esters (PAEs) 1
1.1.1 Characteristic and application 1
1.1.2 Human exposure 2
1.1.3 Toxicities 3
1.1.4 Regulation 4
1.2 Disposable sanitary products (DSP) 5
1.3 Analytical methods for PAEs in diverse matrices 6
1.4 Aims of this study 7
2. Experimental 10
2.1 Chemicals, reagents, and instrument 10
2.1.1 Chemicals 10
2.1.2 Reagents and equipment 11
2.2 Samples 12
2.3 Preparation of solution 12
2.3.1 Standard mix solution 12
2.3.2 Internal standard and surrogate solution 12
2.4 Method development 13
2.4.1 Analytical column 13
2.4.2 Extraction solvent 13
2.4.3 Extraction time 14
2.5 Standard and sample solution preparation 14
2.5.1 Preparation of matrix-matched standard solution 14
2.5.2 Preparation of sample solution 16
2.5.3 GC-MS conditions 16
2.6 Validation 19
2.6.1 Specificity 19
2.6.2 Linearity 19
2.6.3 Limit of detection (LOD) and limit of quantitation (LOQ) 19
2.6.4 Accuracy and precision 20
3. Result and discussion 21
3.1 Method development 21
3.1.1 Oven temperature and column 21
3.1.2 Extraction solvent optimization 23
3.1.3 Ultrasonic extraction time optimization 25
3.2 Validation results 27
3.2.1 Specificity 27
3.2.2 Linearity 29
3.2.3 Accuracy and Precision 31
3.3 Sample Extraction Results 34
4. Conclusion 37
5.References 38MasterDisposable sanitary products (DSPs) are made up of various raw materials including natural/synthetic polymers and adhesives. Phthalate esters (PAEs) are the platicizers used in synthetic polymers such as polystyrene. Because PAEs may be intentionally or unintentionally contained in DSPs from the raw materials or manufacturing processes, there has been growing concerns over the exposure to PAEs from the use of DSPs. In this study, we aimed to develop and validate GC-MS method for simultaneous determination of 15 regulated phthalates and bisphenol A in DSPs. Analytical method was developed through optimization of sample preparation using ultrasonic extraction and GC-MS analytical conditions. Developed analytical method was validated following the ICH guideline in terms of specificity, linearity, LOQ, precision, and accuracy. All of method validation parameters satisfied acceptance criteria, suggesting that this method was suitable and reliable for monitoring the target analytes in DSPs. When this method is applied to the commercial DSPs (N=106), 5 PAEs were found and determined. Our simple and reliable method will be useful as the quality control of PAEs levels in DSPs and further contribute to resolve safety issue as an analytical tool for risk assessment of PAEs exposure from the use of DSPs
영가철-고도 펜톤 공정을 이용한 중성 pH에서의 1,4-dioxane의 분해
No full text학위논문(석사) - 한국과학기술원 : 환경에너지공학학제전공, 2009.2, [ ix, 64 p. ]1,4-dioxane is currently used as a solvent in several industries. Conventional wastewater treatment technologies are ineffective for removal of 1,4-dioxane. Fenton oxidation process, one of the advanced oxidation processes (AOPs), shows high effectiveness for removal of organic contaminants. But traditional Fenton process has narrow working pH range (3~4), needs a lot of hydrogen peroxide, and there is no possibility of recycling the catalyst. In this study solid catalyst, zero-valent iron () was used to overcome limitations of traditional Fenton oxidation process. Oxidation of 1,4-dioxane using microscale was investigated with several major variables-presence of oxygen, initial pH, dose and recycling of was also conducted. Nanoscale was synthesized and compared with microscale in removal efficiency. And ultrasonic irradiation was applied with Fenton process to enhance removal efficiency. In the presence of dissolved oxygen, generated and remove 1,4-dioxane without an addition of oxidant. And removal remained efficient even at high pH. Wide working pH range implies that pH adjustment before treatment is not necessary. The formation of iron oxides did not obviously influence the activity of after recycling the used . And ultrasonic irradiation greatly enhanced removal efficiency through enhancing generation of .한국과학기술원 : 환경에너지공학학제전공
Effect of initial microstructure on irradiation induced microstructure evolution in S-ferrite in an austenitic stainless steel weld
No full textThe irradiation induced microstructure evolution of S-ferrite in an austenitic stainless steel weld was investigated. To simulate long-term service in light water reactor (LWR) at operating temperature, accelerated thermal aging at 400 degrees C up to 30,000 h was performed. Then, proton irradiation up to 10 displacement per atom (dpa) was subsequently conducted for unaged and aged samples. For the unaged samples, formation of Cr-rich (alpha') phase by spinodal decomposition increased with irradiation dose. Meanwhile, formation of G-phase was promoted after 1 dpa, but decreased after 10 dpa. For the aged samples, after 1 dpa irradiation, Cr-rich (alpha') phase formed by spinodal decomposition during thermal aging was destroyed while population of G-phase increased. After further irradiation up to 10 dpa, alpha' phase was re-precipitated and coarsened significantly, but the degree of which was significantly less compared to the unaged samples. Meanwhile, with increase of irradiation to 10 dpa, G-phase population increased for the aged samples. The difference in the evolution of microstructural features during irradiation were discussed in view of the initial microstructure of S-ferrite.
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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