No description available.

No description available.

Sorption/desorption equilibria control the concentrations of P in the soil solution and thereby both its chemical and bioavailability. Apart from the equilibrium phosphorus dynamic, which has been used to determine buffer power and the equilibrium concentration for the studied soils at Cruden Bay, Balmedie, Blairton Wood and Newburgh, the buffer power and equilibrium concentration were affected by the fertiliser incubation period. The differences in PBP and EPC were observed between the soils with high constituents of organic matter and clay in their texture and those which had sandy and sandy loam textures. The glasshouse study was conducted to evaluate the relationship between soil phosphorus availability and two contrasting spring barley genotypes. Both genotypes: Tocada and Natasha responded to added phosphate fertiliser in all treatments. The vegetative growth variations among the genotypes did not appear at different phosphorus levels for most of the studied soils. However, the study has revealed the differences in the root system of Tocada and Natasha in low phosphorus conditions. Tocada was prone to forming large root biomass when compared to Natasha in insufficient phosphorus conditions. Natasha behaved in the opposite way in sufficient phosphorus conditions. The findings of this study confirm that phosphorus use efficiency and root architecture of these genotypes are correlated with each other to exploit more available phosphorus in the rhizosphere. Both Agronomic and physiology Phosphorus use efficiency have been tested. Although the difference in agronomic phosphorus use efficiency among the genotypes was not recorded, some different observations in physiological phosphorus use efficiency among the genotypes were noticeable in some cases.

The purpose of this investigation was to extract, separate, partially characterize and compare the individual phospholipids of the atypical mycobacteria.

Selective coordination to zinc over other members of the first row transition metal series is important for the commercial application of lipophilic ligands for the hydrometallurgic recovery of the metal. In order to achieve selectivity for zinc(n) over other ions, particularly copper(II) and iron(III), ligands have to be designed which take advantage of zinc's preferred tetrahedral coordination geometry and the borderline donor atom preference of the metal. With such ligands in mind, three new classes of ligand system have been designed and synthesised based on the benzimidazole, quinoline and pyridine ring systems with appended phosphinic and thiophosphinic acid anionic donor groups. Benzimidazole ligands which bind zinc in a 2:1 manner in solution have been made and their complexation ability assessed by ESMS, (^31)p NMR, liquid-liquid extraction, fluorescence and UV absorption spectroscopic methods. A bisbenzimidazole ligand with a C(_3) spacer in the 2,2' position was synthesised and shown to bind zinc initially in a 2:1 manner, at low metal concentrations, and predominantiy as a 1:1 species at higher metal concentrations. The formation constant for the ML complex was shown to be logK(_ML)=5 by analysis of the NMR titration curve, which was in close agreement with the value obtained from liquid-liquid extraction studies. A directly linked 2,2'- bisbenziraidazole system was also synthesised as an extension to previous work, however isolation of the target ligand proved to be difficult due to the insolubility of the desired bis-acid.8-(Quinolinyl)phenylphosphinic acid and 8-(2-metiiylquinolinyl)phenylphosphinic acid were also synthesised and their solution complexation behaviour studied in detail. The unsubstituted ligand appeared to form 1:1 complexes with zinc at all the metal concentrations studied, and the absence of the methyl substituent does not inhibit coordination to the ferric ion. In contrast the metiiyl substituted ligand initially forms a 2:1 L:M complex, and 1:1 complexes at higher metal concentrations. The initial ML(_2) complex probably involves coordination of two of the phosphinic acid moieties. Three pyridyl derived ligand systems were also synthesised varying the bulk of the C-6 substituent and the effect of the phosphinic versus the thiophosphinic acid moiety towards zinc coordination was examined. Both of the methyl appended ligands were shown to bind zinc in a 2:1 manner, with the thiophosphinic acid exhibiting a greater avidity for zinc. In contrast, the unsubstituted ligand predominantly forms 1:1 complexes at all metal concentrations.

No description available.

Call number: LD2668 .T4 1950 K39 / Master of Science

本论文主要研究了红磷作为可见光光催化剂在光解水产生氢气方面的应用。所涉及到的催化剂有：纯红磷，万寿菊状的P/YPO₄中空微米球，以及CoP₂修饰的红磷。论文也会讨论WO₃/TiO₂微米六方片及微米棒的制备，并介绍这些新材料在光解水产生氧气方面的应用。 / 第一章：发现了红磷作为可见光光催化材料在光解水制氢气领域的应用。从羟基自由基的检测和光电响应的测量表明，红磷具有在光照下产生电子和空穴的性质。同时，光生电子还原水的能力亦通过理论计算所验证。此外，半导体性质测试表明红磷具有p型半导体的性质。 / 第二章：通过红磷与YCl₃水溶液的反应，合成了万寿菊状的P/YPO₄中空微米球。所得到的微米球由结晶YPO₄纳米片和无定形红磷组成。光解水产生氢气表明，含有53 wt % YPO₄的P/YPO₄的光催化活性是红磷的6倍。同时，文中进一步讨论了中空微米球的形成机理及其光催化活性提高的原因。 / 第三章：研究并证明了CoP₂可以作为红磷光解水产生氢气的共催化剂。CoP₂的修饰可以极大的提高红磷的光解水产氢效率。其中，含2 wt % CoP₂的CoP₂/P的光解水产生氢气的速率较红磷提高了75倍。而且，CoP₂作为共催化剂的效率优于传统贵金属共催化剂Pt。关于CoP₂的共催化机理，初步认为与Co离子的配位作用有关。 / 第四章：通过简单的沉淀、煅烧反应，制备了由WO₃和 TiO₂纳米颗粒组装而成的WO₃/TiO₂微米棒和微米片。可见光氧化水产生氧气测试表明， WO₃/TiO₂复合物的光催化活性为WO₃的2.5倍以上。提出利用“颗粒堆积模型来解释WO₃/TiO₂ 微米棒和微米片的形成机理。 / 第五章：发现了WO₃对甲基蓝染料有趣的吸附性质。首先，利用钨酸铵，四丙基氢氧化铵和氯化钾合成了WO₃纳米棒。所制备的WO₃表现出了对甲基蓝很强的快速吸附能力。而且，WO₃在5s内所吸附的甲基蓝的量与活性炭在30分钟内的吸附相当。此外，通过离子间的作用力和“印迹-吸附过程对WO₃吸附甲基蓝的特性进行了解释。 / This thesis focuses primarily on the development of red phosphorus based visible-light-driven photocatalysts for hydrogen production from water. These materials include pure red phosphorus, hierarchical P/YPO₄ hollow microspheres, and CoP₂ loaded red phosphors. The fabrication of WO₃/TiO₂ microrods and plates with enhanced photocatalytic water oxidation property is also discussed. / Chapter I:Red phosphorus was discovered as a new visible-light driven photocatalyst for H₂ formation from the reduction of water by photogenerated electrons. The detection of hydroxyl radicals and results from photoconductivity measurements confirmed the photogeneration of electrons from the red phosphorus. Theoretical calculations indicated that the reduction of water by photogenerated electrons would be energetically possible. Moreover, a P-type semiconductor behavior of red phosphorus was observed. / Chapter II:Hierarchical P/YPO₄ hollow microspheres with enhanced photocatalytic activity than the individual components for hydrogen formation were prepared. The composite was synthesized by the reaction from amorphous red P and YCl₃ aqueous solution via a hydrothermal method. The final product consisted of crystalline YPO₄ nanosheets and amorphous red phosphorus. The composite with 53 wt % YPO₄ was up to 6 times more active than red phosphorus under visible light irradiation. The formation mechanism of hierarchical microspheres and the enhanced photocatalytic activity were discussed. / Chapter III:CoP₂ loaded as a cocatalyst significantly enhanced the rate of H2₂ formation from water over red phosphorus under visible light irradiation. The rate of H₂ formation over red P was increased by up to 75 times when loaded with 2 wt % CoP₂. The performance of CoP₂ as a cocatalyst was even higher than that of Pt. The coordination effect of Co ions was proposed to explain the enhanced photocatalytic activity by CoP₂ loaded. / Appendix I:WO₃/TiO₂ microrods and microplates assembled from WO₃ and TiO₂ nanoparticles were prepared by simple precipitation and calcination processes. Their photocatalytic properties for O₂ formation from water were investigated. The composites were c.a. 2.5 times more active than WO₃ in photocatalytic O₂ formation under visible light irradiation. The formation mechanism of WO₃/TiO₂ microstructures was explained from “particle packing mode“. / Appendix II:An interestingly adsorption property of hexagonal tungsten trioxide to MB was discovered. The WO₃ were prepared from ammonium metatungstate, tetrapropyl ammonium hydroxide and potassium chloride. The product exhibited a high adsorption capacity toward methylene blue (MB), and the time required for reaching adsorption equilibrium was less than 5 seconds. The amount of MB adsorbed by WO₃ in 5 s was equivalent to that adsorbed by activated carbon for 30 min. Ionic interaction and “imprinting-adsorption“ were proposed to explain the adsorption property of as-prepared WO₃ sample. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wang, Feng. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract (Chinese) --- p.i / Abstract --- p.iii / Acknowledgement --- p.vi / List of Figures --- p.viii / List of Tables --- p.xviii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Basic Principles of Photocatalytic Water Splitting --- p.1 / Chapter 1.2 --- Strategies to Develop Visible-light-driven Photocatalysts --- p.3 / Chapter 1.2.1 --- Native visible-light-driven photocatalysts --- p.3 / Chapter 1.2.2 --- Doping --- p.6 / Chapter 1.2.2.1 --- Metal or non-metal ions doping --- p.6 / Chapter 1.2.2.2 --- Co-doping --- p.10 / Chapter 1.2.2.3 --- Homogeneous doping --- p.12 / Chapter 1.2.3 --- Solid solution photocatalysts --- p.15 / Chapter 1.2.4 --- Dye sensitized photocatalysts --- p.17 / Chapter 1.3 --- Strategies to Enhance Photocatalytic Efficiency --- p.19 / Chapter 1.3.1 --- Semicondutor combination --- p.19 / Chapter 1.3.1.1 --- Inorganic sensitization --- p.20 / Chapter 1.3.1.2 --- Bidirectional charge-carrier transfer --- p.21 / Chapter 1.3.1.3 --- Indirect Z-scheme --- p.22 / Chapter 1.1.1.4 --- Direct Z-scheme --- p.23 / Chapter 1.3.2 --- Cocatalyst loading --- p.24 / Chapter 1.3.2.1 --- Noble metal cocatalysts --- p.24 / Chapter 1.3.2.2 --- Metal oxide cocatalysts --- p.25 / Chapter 1.3.2.3 --- Metal sulfide cocatalysts --- p.26 / Chapter 1.3.2.4 --- Mixed cocatalysts --- p.27 / Chapter 1.3.3 --- Hydrogen Generation Systems Containing Sacrificial Reagents --- p.32 / Chapter 1.4 --- Summary --- p.34 / Chapter 1.5 --- Aim of This Thesis and Its Significance --- p.35 / Chapter 1.6 --- References --- p.36 / Chapter Chapter Two --- Red Phosphorus: An Elemental Photocatalyst for Hydrogen Formation from Water under Visible Light Irradiation --- p.52 / Chapter 2.1 --- Introduction --- p.52 / Chapter 2.2 --- Experimental --- p.54 / Chapter 2.2.1 --- Synthesis --- p.54 / Chapter 2.2.1.1 --- Preparation of crystalline red phosphorus --- p.54 / Chapter 2.2.1.1 --- Preparation of red phosphorus films --- p.54 / Chapter 2.2.2 --- Characterization --- p.55 / Chapter 2.2.3 --- Gas evolution tests --- p.56 / Chapter 2.2.4 --- Detection of photogenerated OH radicals --- p.56 / Chapter 2.2.5 --- Computational details --- p.57 / Chapter 2.2.6 --- Photoconductivity measurements and electrical tests --- p.57 / Chapter 2.3 --- Results and Discussion --- p.59 / Chapter 2.4 --- Conclusions --- p.74 / Chapter 2.5 --- References --- p.75 / Chapter Chapter Three --- Hierarchical P/YPO4 Microsphere for Photocatalytic Hydrogen Production from Water under Visible Light Irradiation --- p.79 / Chapter 3.1 --- Introduction --- p.79 / Chapter 3.2 --- Experimental --- p.81 / Chapter 3.2.1 --- Synthesis --- p.81 / Chapter 3.2.2 --- Characterization --- p.81 / Chapter 3.2.3 --- Gas evolution tests --- p.82 / Chapter 3.3 --- Results and Discussion --- p.83 / Chapter 3.4 --- Conclusions --- p.95 / Chapter 3.5 --- References --- p.95 / Chapter Chapter Four --- Enhancement of Photocatalytic H₂ Formation from Water over Red P by Loading CoP₂ as Cocatalyst --- p.99 / Chapter 4.1 --- Introduction --- p.99 / Chapter 4.2 --- Experimental --- p.100 / Chapter 4.2.1 --- Synthesis --- p.100 / Chapter 4.2.2 --- Characterization --- p.101 / Chapter 4.2.3 --- Hydrogen formation tests --- p.101 / Chapter 4.3 --- Results and Discussion --- p.103 / Chapter 4.4 --- Conclusions --- p.109 / Chapter 4.5 --- References --- p.109 / Chapter Chapter Five --- Conclusions and Future Work --- p.112 / Chapter 5.1 --- Conclusions --- p.112 / Chapter 5.2 --- Recommendations for future work --- p.112 / Chapter Appendix I --- WO₃/TiO₂ Microstructures for Photocatalytic Water Oxidation under Visible Light Irradiation --- p.114 / Chapter AI.1 --- Introduction --- p.114 / Chapter AI.2 --- Experimental --- p.116 / Chapter AI.2.1 --- Sample preparation --- p.116 / Chapter AI.2.1.1 --- Precursor synthesis --- p.116 / Chapter AI.2.1.2 --- Synthesis of assembled WO₃/TiO₂ microstructures --- p.118 / Chapter AI.2.2 --- Characterization --- p.119 / Chapter AI.2.3 --- Oxygen formation tests --- p.120 / Chapter AI.3 --- Results and Discussion --- p.121 / Chapter AI.4 --- Conclusions --- p.137 / Chapter AI.5 --- References --- p.137 / Chapter Appendix II --- Hexagonal Tungsten Trioxide Nanorods as a Rapid Adsorbent for Methylene Blue --- p.142 / Chapter AII.1 --- Introduction --- p.142 / Chapter AII.2 --- Experimental --- p.143 / Chapter AII.2.1 --- Sample preparation --- p.143 / Chapter AII.2.2 --- Characterization --- p.144 / Chapter AII.3 --- Results and Discussion --- p.145 / Chapter AII.4 --- Conclusions --- p.159 / Chapter AII.5 --- References --- p.159 / List of Publications --- p.163

Low Impact Development (LID) techniques for site design are increasingly being utilized to mitigate the negative impacts associated with stormwater runoff, and green roofs are one such application. The ability of green roofs to reduce the total and peak volumes of stormwater runoff has been fairly well documented, but performance varies in different climate zones, and there is limited information available regarding green roof effectiveness in New England, a region whose weather patterns are notoriously variable from season to season and often even day-to-day. Additionally, there are questions regarding the impact that green roofs have on water quality, especially regarding phosphorus. While many green roofs have been found to leach phosphorus into stormwater runoff within the first few years after installation, it is assumed that this phenomenon will not continue after the green roof vegetation has been established. However, it is still unclear whether or not this assumption is valid, and very few research projects have focused on providing the necessary insight into the hydrologic and geochemical processes that are contributing to this observed problem. The Nitsch/Magliozzi Green Roof, located atop WPI's newest residence hall, was donated to enhance the sustainability of the building and to foster continued research and education. This roof provided an opportunity to better characterize the relationship between rainfall and runoff volumes, phosphorus sorption/desorption in the growing medium, and plant uptake processes. Comparisons of grab samples of stormwater from both the green and non-green portions of the roof within the first few seasons following installation confirmed that phosphorus was leaching into the runoff, and some seasonal trends were observed. For example, the highest concentrations (3-13 mg/l P-PO4-3) were observed during an especially rainy summer. In order to gain a better understanding into the nature of this occurrence, laboratory experiments on sections of this same green roof were designed and set up in WPI's greenhouse. A series of simulated rainfall events were conducted, a mass balance approach was used to analyze flow, and the phosphorus content of the water, plants, and soil were assessed. For flow attenuation, the green roof panels performed as expected under different rainfall and antecedent moisture conditions. Additionally, the greenhouse experiments provided improved insight into the nature of the relationship of phosphorus between the flow conditions, plant uptake, and soil processes, as well as its distribution throughout a storm. The laboratory data further provides a basis for estimating performance of a green roof and its long-term impact on stormwater quality. In a broader context, the findings also serve to inform future extensive green roof designs and subsequent research efforts.

Typescript (photocopy). / Digitized by Kansas Correctional Industries