• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 513
  • 134
  • 47
  • 44
  • 39
  • 31
  • 21
  • 20
  • 20
  • 20
  • 20
  • 20
  • 10
  • 6
  • 6
  • Tagged with
  • 1050
  • 291
  • 212
  • 106
  • 103
  • 93
  • 88
  • 83
  • 82
  • 82
  • 73
  • 72
  • 63
  • 63
  • 60
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
341

Semiotic assemblages and the manifestations of material culture in selected chicken licken advertisements

Fortuin, Dionne January 2021 (has links)
Magister Artium - MA / With advances and information technology innovation, and the rise of revenue through advertisements, producers and content creators have become creative in the selection of cultural and semiotic materialities, and linguistic resources for the production of advertisements. Bearing in mind, the political landscape of South Africa and its history, producers have an abundance of cultural and semiotic artefacts in time and space to draw from, and to indulge their creative licence to come up with novel designs and concepts for their advertisements and brand identities. The thesis explored the use of local and transnational linguistic and other cultural objects as semiotic material in the design and construction of selected Chicken Licken advertisements. The specific objectives explored include; 1) local and global cultural elements in selected Chicken Licken advertisements; 2) the local and global identity affiliations in advertisement selection and production; and, 3) the translocalization and transnationalization of cultural flows as represented through semiotic materials.
342

COST-EFFECTIVE STRATEGY FOR THE INVESTIGATION AND REMEDIATION OF POLLUTED SOIL USING GEOSTATISTICS AND A GENETIC ALGORITHM APPROACH / 土壌汚染調査と浄化のための、地球統計学と遺伝アルゴリズム手法を用いた費用効果戦略

Yongqiang, Cui 23 March 2016 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19697号 / 工博第4152号 / 新制||工||1641(附属図書館) / 32733 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 米田 稔, 教授 清水 芳久, 准教授 藤川 陽子 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
343

Remediation Approach for Improving Acid Mine Drainage Conditions Using Slow Release Hydrogen Peroxide Systems

Wolbert, Ryan A. 02 June 2020 (has links)
No description available.
344

EFFECTS of PEARSON’S DIGITAL LEARNING SOLUTION ON THE 11TH GRADE STUDENTS’ ACT GROWTH IN A REGIONAL EDUCATION CONSORTIUM IN NORTHWEST OHIO

Belcher, Erik M. 23 July 2020 (has links)
No description available.
345

CONTAMINANTS REMOVAL AND RARE EARTH ELEMENTS RECOVERY FROM COAL MINE DRAINAGE BY USING (BIO)(ELECTRO) CHEMICAL METHODS

Peiravi, Meisam 01 August 2018 (has links) (PDF)
Mining activities, as essential as they are for our economy and our society, bring pollutants such as acid mine drainage (AMD) which contains dissolved metal(loid)s into the environment. There are different technologies currently being practiced to treat AMD, but many of these methods are prohibitive in industry due to high energy, material and labor requirements. This study investigated two emerging technologies to treat AMD with high removal rates of some metals. In addition, as AMD contains strategic metals such as rare earth elements (REEs), hydrometallurgical and biosorptive approaches were used to recover REEs from AMD, hydrometallurgical recovery method was also applied for coal by-products for the method developed. A two-chamber bioelectrochemical system (BES) was used to remove different types of metals from AMD. After 7 days, the pH of the cathode solution increased from 2.5 to 7.3. More than 99% of Al, Fe and Pb were removed, and removal rates of 93%, 91%, 89% and 69% were achieved for Cd, Zn, Mn, and Co, respectively, at the biocathode. Energy-dispersive X-ray spectroscopy (EDS) studies revealed the deposition of the various metals on the cathode surface, and some metals were detected in precipitates from the cathode chamber. During the BES operation, ~30-50 mV of closed circuit voltage was obtained for different conditions. A single-chambered BES study was conducted for the removal of Cd, Ni, and Mn in mine drainage. Compared to a double chamber, a single chamber BES is easier to design and operate. The removal process was studied with activated sludge from a local wastewater treatment plant. The effect of applied voltage, time, and initial concertation of these metals on their removal rate was studied. For Cd initial concentrations of 625 and 165 µg/L, 1.0 V showed the highest removal efficiency, and ~93 and 95% of Cd were removed, respectively. For a Ni initial concentration of 2,440 µg/L, 72% was removed under 1.0 V compared to the control of 77%. However, for a lower initial Ni concentration of 190 µg/L, 1.0 V was better compared than other conditions, and it removed 92% of Ni. For a Mn initial concentration of 1,800 µg/L, 1.0 V had a better result, however, only ~19% of the Mn was removed. For a lower Mn initial concentration of 390 µg/L, 1.0 V was favorable only at 24 h and the removal rate was ~37%. Nanoscale zerovalent iron (nZVI) was used to remove contaminants from AMD. These contaminants include transition metals (Co, Ni, Cu, Mn, and Zn), alkali and alkaline earth metals (Li, Mg, and Ca), metalloid (As), nonmetals (Se and S), and active metal (Al). Purchased nZVI in concentrations of 10-6500 mg/L was used for a reaction duration of up to 480 min. The pH of the AMD increased linearly with increasing concentrations of nZVI, with a maximum of 6.0±0.1 at 6500 mg/L of nZVI. Cu and Al had the highest removal rate among all other elements. With 10 mg/L of nZVI, ~100% of Cu was removed within 120 min. Up to ~98% of Al was removed with 5000 mg/L of nZVI in 480 min. Reuse of the purchased nZVI was studied for the first time for AMD treatment; however, after reuse in the second cycle, the nZVI was no longer effective. Lab-made nZVI by the precipitation method was tested for a longer time of 48 h. Removal rates for different elements did not change after ~8 h (e.g., 480 min), and in general, the lab-made nZVI had better removal efficiency compared to the purchased nZVI, with removal rate of ~28-79% when using 80 mg/L of the lab-made nZVI. Besides Cu, Al, Ni, and Co, successful removal of Mg and Ca, as well as S, Co, Li, As, and Se from AMD was reported for the first time by using nZVI. Different coal ranks were examined for REE concentration from coal ash. Maximum REE content of more than 700 mg/kg was observed for the highest-rank coal (anthracite) sample, and that was used for leaching and recovery studies. Hydrometallurgical processes including leaching, solvent extraction, stripping, and precipitation were performed to recover REEs from coal ash. Nitric acid leaching tests were conducted at 95 ℃ using a 4×2×2 factorial design. The results indicated that the highest rate of light REEs (LREEs) recovery was achieved at the highest molarity of the acid solution, lowest solids content and longest retention time. However, the highest rate of heavy REEs (HREEs) recovery needed only an intermediate level of acid molarity. The highest recovery rates of 90% for LREEs and 94% for HREEs were obtained. Recirculation of the leachate was conducted to prepare the REE-concentrated solution for the solvent extraction. After two stages of leaching, a 33 mg/L of TREE concentration was obtained in the leachate. Solvent extraction (SX) tests conducted using three different extractants, namely, TBP, D2EHPA and Cyanex 572, and their combinations showed that D2EHPA was the best extractant for recovering REEs from the nitric acid leachate solution with an extraction efficiency of 99%. Nitric acid and sulfuric acid and their mixture were used in the stripping tests. The effect of solvent concentration (in the SX process) was also studied in the stripping stage. When 50% solvent concentration was used, a maximum of 58% stripping recovery was obtained. Oxalic acid helped precipitate ~94% of total REEs (TREEs) from the above aqueous solution. Calcination of the product was performed to reach a final product of 0.8% rear earth oxides (REOs). The same process flowsheet was also successfully tested for another coal ash sample. To recover REEs from AMD, two different approaches were carried out including hydrometallurgical technique and more environmentally friendly approach- biosorptive recovery. A complete process flowsheet including either solvent extraction or biosorption, followed by stripping, and precipitation was developed to recover REEs from an unconventional source of AMD for the first time. At the natural pH of 2.5 almost all REEs were extracted from the solution. Metal-loaded organic solution was reused for three cycles, and it was shown that after three cycles, there was no major reduction in the capacity of the extractant. Striping with 6.0 M HNO3 recovered 23.9±0.7, 74.7±2.1, and 53.1±1.4% of LREEs, HREEs, and TREEs from the organic phase accordingly. Using oxalic acid, and for pH of 2.0, 92.9±2.8% of LREEs, 10±1.5% of HREEs, and 56.2±1.8% of TREEs were precipitated. In the biosorptive extraction, >99% of TREEs were extracted from the solution. The REE-bearing bacteria was also stripped with 6.0 M HNO3, 2871.3±114.8 µg/L (45.0±1.8%) LREEs, 3851.0±154.0 µg/L (65.0±2.6%) HREEs, and 6722.0±268.9 µg/L (50.0±2.0%) TREEs were obtained. Both hydrometallurgical and biosorptive methods extracted almost all of the REEs in the AMD, though pH was adjusted to 4.0 for the biosorptive method. After stripping, comparable amounts of TREEs were obtained by both methods.
346

A PHENOMENOLOGY OF PLACEMENT: EXPLORING STUDENT PERCEPTIONS OF THE LINKS AMONG REMEDIAL OPPORTUNITY STRUCTURES, ACADEMIC ABILITY, AND BELONGING IN AN URBAN COMMUNITY COLLEGE

Marcotte, Madeline R. January 2021 (has links)
This phenomenological study explored both the students' lived experiences of placement processes at an urban community college and their consciousness of those experiences. By applying phenomenological methodology within an engaged inquiry framework, this study integrates multiple perspectives into a narrative thread to make sense of students' experiences with placement and the prospect of remediation. Further, this study sought to understand not only how that prospect is socially constructed but how it affects the students' integration into higher education. By applying socio-cultural theories of ability and ability development as a lens, the study focused on the relationships among the students' understanding of remedial structures, of their own academic ability, and of their sense of belonging in higher education. / Urban Education
347

Heavy metal removal from soil by complexing reagents with recycling of complexing reagents

Xie, Ting, 1971- January 2000 (has links)
No description available.
348

Regeneration of heavy metal contaminated soil leachate with chitosan flakes

Soga, Benedictus Hope. January 2001 (has links)
No description available.
349

Recycling of complexometric extractant(s) to remediate a soil contaminated with heavy metals

Lee, Chia Chi January 2002 (has links)
No description available.
350

Microwave-enhanced extraction of organic contaminants from soil

Punt, Monique M. January 1997 (has links)
No description available.

Page generated in 0.0427 seconds