The aim of this project was to produce solid adsorbents and catalysts in a continuous flow process. These materials are traditionally made in a batch process. The materials were made and the effect of the change in synthesis explored. When hydrotalcite was produced in a batch process it was found to yield material that was synthesised by a reaction governed by thermodynamic control. Contrary, solid formation in a continuous flow it was found to be governed by a kinetically controlled reaction. During the batch reaction the reactants had time and mobility to precipitate, dissolve and re-precipitate in order to arrive at the lowest energy configuration. This configuration resulted in aluminium from one meixnerite intermediate layer aligning with aluminium in the opposing layer (referred to as “in phase”). This allowed carbonate anions to join the layers together creating a crystalline structure by balancing its charge between the two aluminium atoms. In a continuous flow process the reactants were not afforded either the time or space to move. This resulted in aluminium being randomly located within the meixnerite intermediate. Due to the random placement of aluminium, the aluminium in opposing layers did not consistently align (referred to as “out of phase”). Carbonate anions bound to these out of phase aluminium atoms are unable to balance their charge by linking layers together. The anions compensated by taking up hydrogen and forming a bicarbonate anion. The remaining aluminium took up monovalent nitrate anions in the absence of any divalent anions. Hydroxide anions would have been more favourable but they were required in the formation of the lattice. It was also found that the kinetically controlled product could be converted to the thermodynamically controlled product by washing. Washing, however, degraded the lattice structure and washed away an amount of material. The hydrotalcites produced by continuous flow process were thermally decomposed to act as a carbon dioxide adsorbent. They decomposed much faster than their batch counterparts, suggesting the carbonate bridge provides thermal stability to the material. The decomposition also revealed that the magnesium/aluminium spinel recorded in other studies did not form for the materials produced in a continuous flow process. Instead the material decomposed to the separate metal oxides. This did not have an effect on the ability of the material to adsorb carbon dioxide and performed comparably to the batch process materials. The continuous flow process was used to create a Ni/Mg/Al hydrotalcite that could be used as a catalyst in ethanol steam reforming. The continuous flow process allowed three processes for introducing nickel into the system: the doping of the starting reagents, ion exchange during the washing process and the impregnation of the dry product. The doped samples produced material comparable to those produced in continuous flow without doping or washing. The ion exchange and the impregnation samples produced samples that are comparable to those produced in continuous flow with washing The doped samples exhibited a fourth region of weight loss in thermogravimetric analysis which is speculated to be the formation of nickel aluminide at high temperatures. The catalytic activity corroborated this idea with an increase in metallic behaviour. The doped sample was found to be the more active sample tested. In order to further test the effect of kinetic and thermodynamic control during the continuous flow process, an attempt to control the particle size of zirconium basic sulfate was made. It was found that the particle size could be altered in the batch process due the variable environment within the reactor. Inefficient mixing created concentration gradients and inefficient heating created temperature gradients. It was these gradients within the batch reactor that facilitated the thermodynamic product to be produced and the particle size to increase. In a continuous flow reactor these gradients did not exist. The advantage of the flow reactor was the ability to control the environment of the reactor in an even and uniform manner. The uniformity of the reactor environment eliminated any temperature or concentration gradients, keeping all the materials at similar chemical potentials, limiting particle growth.

The ongoing depletion of fossil fuels and the severe consequences of the greenhouse effect make the development of alternative energy systems crucially important. While hydrogen is, in principle, a promising alternative, releasing nothing but energy and pure water. Hydrogen storage is complicated and no completely viable technique has been proposed so far. This work is concerned with the study of one potential alternative to pure hydrogen: ammonia, and more specifically its storage in solids. Ammonia, NH3, can be regarded as a chemical hydrogen carrier with the advantages of strongly reduced flammability and explosiveness as compared to hydrogen. Furthermore, ammine metal salts presented here as promising ammonia stores easily store up to 50 wt.-% ammonia, giving them a volumetric energy density comparable to natural gas. The model system NiX2–NH3 ( X = Cl, Br, I) is studied thoroughly with respect to ammine salt formation, thermal decomposition, air stability and structural effects. The system CuX2–NH3 ( X = Cl, Br) has an adverse thermal decomposition behaviour, making it impractical for use as an ammonia store. This system is, however, most interesting from a structural point of view and some work concerning the study of the structural behaviour of this system is presented. Finally, close chemical relatives to the metal ammine halides, the metal ammine nitrates are studied. They exhibit interesting anion arrangements, which is an impressive showcase for the combination of diffraction and spectroscopic information. The characterisation techniques in this thesis range from powder diffraction over single crystal diffraction, spectroscopy, computational modelling, thermal analyses to gravimetric uptake experiments. Further highlights are the structure solutions and refinements from powder data of (NH4)2[NiCl4(H2O)(NH3)] and Ni(NH3)2(NO3)2, the combination of crystallographic and chemical information for the elucidation of the (NH4)2[NiCl4(H2O)(NH3)] formation reaction and the growth of single crystals under ammonia flow, a technique allowing the first documented successful growth and single crystal diffraction measurement for [Cu(NH3)6]Cl2.

Super-elastic scattering measurements were taken from calcium using the spectrometer described in this thesis. Calcium atoms were excited from the 41S0 ground state to the 41P1 excited state using a high resolution continuous wave laser set to a wavelength of 423 nm. A beam of electrons with a well defined energy was directed at the laser excited calcium atoms. The excited state was then described by a set of atomic collision parameters P_lin, gamma and L_perp, found from measuring scattered electrons as a function of scattering angle and energy. The scattering chamber was held at a pressure of 3x10 -7 mbar. A resistively heated oven operating at 800 degrees celsius produced a well collimated calcium atomic beam containing the calcium atoms. The electron gun generated a beam of electrons of well defined momentum, whose energy could be changed from ~5 eV to over 100 eV. At energies less than 20 eV the rate of super-elastic electrons was very low, and so modifications were made to the spectrometer to automate data collection for long operating times without the need for user intervention. A new digitally controlled DC voltage supply was constructed to deliver the correct potentials to the electron-optical elements in the spectrometer. An internal microcontroller enabled supply voltages to be programmed either using the front panel or via an attached computer for automatic optimisation of spectrometer voltages using a simplex algorithm. New data was collected for the collision parameters over the full accessible angular range from 25--140 degrees, at energies of 8, 10 and 65 eV. The data at 8 and 10 eV was taken so as to resolve differences between theoretical models at low energies. Comparisons were made with a relativistic distorted wave calculation, an R-matrix calculation, an R-matrix calculation using B-splines and a convergent close coupling theory. A 2 eV discrepancy was identified in the measured electron energy which was thought to be due to stray fields in the chamber. With this considered, convergent close coupling predictions were found to be in excellent agreement with the experimental data.

唐劉知幾著有《史通》一書，當中總結歷代史籍的編撰情況，更提出史籍撰著建議予以後世，但見劉知幾學術之重點在於其史學。事實上，後世學者往往著眼於劉知幾「三入東觀」的經歷以及其僅存的史評論著《史通》，即冠以「史學家」之稱謂，討論其史學觀念，子玄之儒學背景及其於論著中如何受儒家經典影響，並未為過往一眾論者廣泛注意，但觀《全唐文》對子玄的評價，稱「子玄博識，誠則純儒」，由此可見，唐時人對於劉知幾的學術焦點並不在史學，恰正在其儒學。 / 晚唐柳璨指摘劉知幾《史通》議駁經典過當，為批評《史通》菲薄經典之始，至近人呂思勉猶稱其「邃於史而疏於經」，雖自梁啟超起意圖匡正歷來學者對劉知幾的誤解，但不論學者採取批評抑或肯定的論說立場，並皆以為劉知幾論說有悖儒家經典，甚至以為劉知幾貶抑經書以求推尊史學。但筆者嘗試蒐集書證，得見一眾論說其實未有深究劉知幾的經學內涵，即論斷其著述意圖，實有偏頗之弊。 / 本文欲從《史通》內外分篇準則的角度切入，析述《史通》內篇辨義、外篇言事之編排體例，且以此理解《史通》出現「詆毀」經書論說，旨在論史事真偽，非關經義，藉以肯定劉知幾殆非「離經叛道」之徒。 / 再以《史通》及相關史籍著述論及儒家經典的條目為研究對象，比對初唐相關經學論說，以歸納劉知幾的經學思想，當中包括了對《尚書》、《春秋》相關經學議題的闡發，以及詮釋三《禮》、《周易》、《詩經》的傾向與特點。 / 最後，將《史通》說經論述置於經學史的發展脈絡下審視，得見《史通》「疑古」「惑經」乃上承王充學說，又因唐初經學治學風氣崇尚自由，得以包容接納有異於《正義》的論見。其次，透過梳理唐以後相關經說，但見作為史書類之《史通》對經學方面的影響，包括《春秋》學派繼承「捨傳求經」之風，而後世經學論述對劉知幾學說之廣泛引用，因之，本文以為劉知幾學識在經學範疇亦有影響力，實需重新考量劉知幾於經學史上的地位。 / As a celebrated scholar in Tang Dynasty, Liu ZhiJi（劉知幾） expressed his thoughts in the works of Shi Tong（史通）. Shi Tong, an echo-making significance in the history of Chinese historiography. It does not only make a summary of historical records in the past, but also provide a guideline for the later historiographers. Therefore, the mainstream of research on Liu, is about the historical thoughts. However, we have to realize that, Liu’s thoughts on Classics studies have also been mainly included in Shi Tong. Moreover, Quan Tang Wen（全唐文） said "Liu is a knowledge man, can be called an absolute Confucian scholar." This has shown that the essence of Liu’ study is on Confucian Classic but not on history. / In Shi Tong, Liu points out the advantages and disadvantages of the historical records, even Saint Confucian Classic. Liu Can（柳璨） in later Tang Dynasty, reprimands it as "Absurd accusation of the sages and Saint". There are even more commentaries in Shi Tong in modern time, yet most held biased views. After reviewing the research of previous scholars, we found that, regarding the research of Classic study in Shi Tong still somewhat weak even Tang Dynasty, in the past decades. / This paper starts from discussing the writing system of Shi Tong. Shi Tong is divided into inside and outside parts. According to the research, the inside part is talk about the theory of historical writing, and the outside part focus on the historical fact. The differences between these structures, help us to understand Liu’s concept of Confucian Classic. He did not doubt about the value of Confucian classic, but use the paradigm of the history to seek the fact of history in the Classic writings. / The second part of this paper, is to analyze the thoughts of Classic in Shi Tong. It divides into 5 chapters to talks about Shang Shu, Chun Qiu, Li Ji, Zhou Yi and Shi Jing, These chapters attempt to show the deeply studies on Shi Tong’ explanations and interpretation of Classic. Through the discussion of Liu’s thoughts of Classic study, we can understand more clearly about Liu’s distinct mentality and academic survey. / In the third part of this paper, we re-examine the background of Liu’s world culture. Even some scholars may recognized Liu’s doubt about Classic, and simply labeled or explained this phenomenon, saying Said that Liu’s thought was deviated from authority unifying thought of Classics. Liu didn’t follow or opposed the predecessors blindly. At the same time, Liu created his own views of Classic study. He approved and developed the critical spirit of Wang Chong(王充), who said "Hate bitterly dishonest and absurd gossip." Meanwhile, the atmosphere of Classic study in the early of Tang Dynasty is quiet free comparatively speaking. That is the reason that Liu voiced his doubt on the Classic. / To find out Liu’s basic thoughts, or the reason he doubted about the classic, was pursuing the historical fact. He wouldn’t want to overthrow the authoritative status of Classic, and his inner intension was to renewal the Classic. It is closed to the proposition of new Chun Qiu party. Liu’s viewpoints on Classic issues were approved in Tang Dynasty. Furthermore, the views were also being adopted in the Classic works in the following decades. It shows that, Liu occupied an important position in the history of Classic study. / 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. / 劉璐. / Thesis (M.Phil.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 214-235). / Abstracts in English and Chinese. / Liu Lu.

No description available.

Silver nanoparticles (sub 10 nm), supported on, or in, cellulose, have been demonstrated to be well stabilised and immobilised during application in a model continuous reaction: the reduction of 4-nitrophenol (4-NP) to 4-aminophenol with sodium borohydride. The production of these silver nanoparticles (NP), within the cellulose supports, was carried out by either in situ reduction of silver precursors absorbed into the preformed cellulose supports, or, by inclusion of ex situ synthesised NPs (prepared in DMSO solutions) in the dissolution of cellulose and trapping upon subsequent coagulation of cellulose. The effects of NP synthesis method (affecting particle size and agglomeration) and the cellulose morphology and porous structure were examined with respect to the catalytic activity of the materials. The in situ reduction of a silver salt with aqueous NaBH4 solutions (0.03 to 1.0 wt. %) led to tuneable Ag NP sizes with mean diameters of 5 to 11 nm (TEM) and metal loadings of 0.5-1.0 wt. %. The catalytic activity of these samples in the 4-NP reduction reaction (0.05 mM, 0.167 M NaBH4, 30 °C) was demonstrated to increase upon decreasing NP size: TOF values of 22–356 h-1, consistent with a Langmuir-Hinshelwood mechanism. The porous structure of these Ag-cellulose materials (0.2 to 294 m2 g-1) was demonstrated to be variable and dependent on drying treatments of the regenerated cellulose hydrogel. Thermal drying, freeze-drying and critical point drying resulted in materials with different bulk structure and porosity. In turn the different porosities resulted in extremely different catalyst activities, e.g. Ag-cellulose catalyst (0.3 mm disks) thin film, hydrogel and cryogel phases exhibited TOF values of 2, 12 and 178 h-1, respectively. In addition, the NP synthesis could be carried out in either the cellulose hydrogel or cryogel, which led to different extents of Ag NP catalyst stabilisation against agglomeration during the 4-NP reaction and catalyst recovery and recycling. The Ag NPs synthesised in the cryogel cellulose disks were observed to undergo agglomeration (TEM) after use in 4 repeat batch reductions, whilst those NPs synthesised in the hydrogel cellulose, prior to freeze-drying to the final cryogel catalyst material, did not exhibit any agglomeration upon 4 repeat reduction reactions. The ex situ reduction of Ag and Au NPs was carried out by the reduction of AgOAc and Au(OAc)3 by DMSO and variation of the NP synthesis parameters, such as time (10 min – 1h) and temperature (50 – 80 °C), allowed for control of the NP sizes (3 to 6 nm Ag NPs and 4 to 11 nm Au NPs, TEM). It was demonstrated that the addition of the polysaccharide starch (0.42 wt. % in DMSO) allowed for consistent Ag NP size (ca. 4 nm) to be achieved throughout the 8 h synthesis, the starch acting as both the reducing and capping agent, maintaining the small sizes and narrow particle size distributions of the NPs upon aging (72 h). A kinetic model with a bimolecular nucleation step was developed to describe this reduction of the silver acetate by the starch/DMSO system. However, contact of the NPs with solutions of imidazolium ILs, 1-Ethyl-3-methylimidazolium acetate (EmimOAc) and 1-Butyl-3-methylimidazolium chloride (BmimCl) in DMSO, used in the dissolution of cellulose, led to the oxidation of the Ag(0) and Au(0) NPs. Thus, when these NP solutions were mixed in cellulose solutions regeneration by phase inversion with the aim of preparing cellulose/NP composites led to materials with negligible metal loadings (AAS). This oxidation, of the metal NPS, was partially overcome by stabilisation of the starch capped Ag NPs by pre-treatment with cellulose (1:1 mixture of α and MC cellulose). However, the activity of the resulting Ag-cellulose catalyst (0.5 wt. % AAS, 6.7 nm TEM) was much lower than the Ag-cellulose catalysts prepared by in situ reduction of silver in the cellulose hydrogel, despite the comparable NP sizes. This was presumed to be a result of encapsulation of the Ag NPs by the cellulose, leading to a decrease in the accessible surface of the NPs. Finally, the use of Ag NP / cellulose composites, prepared by in situ reduction of silver in cellulose hydrogel beads (0.19 wt. %, 6.4 nm), were demonstrated in the continuous reduction of 4-NP in a packed bed reactor (τ’ 100 g s dm-3). The activation energies of the reactions of 4-NP catalysed by the Ag-cellulose catalyst materials were determined (3.2 to 9.4 kJ mol-1) from Arrhenius plots, which demonstrated that above 20 °C the reaction was likely subject to diffusion limitations in the cellulose beads. The high degree of stabilisation of the Ag NPs against agglomeration imparted by the cellulose support was demonstrated: the rate of reaction was observed to be constant over 120 h, treating 45 L of 4-NP solution, with the catalyst material after use demonstrating no significant leaching of silver, or agglomeration, of NPs (AAS, TEM).

Drawing on a variety of primary and archaeological sources, this study attempts to recreate the political history and the social and economic character of the Balqa' region during the Umayyad period. The Balqa' was a provincial area of Transjordan, which had long been part of the classical world heavily influenced by the Arab tribes of the Syrian desert. After the Arab conquest the Balqa' took on a new role as the home or some of the ruling Umayyad elite. But a process of economic, demographic and urban decline had already begun in the middle of sixth century. Even the ethnic and religious composition of the Balqa's population remained stable; the region was primarily inhabited by Christian Arabs during both the late Byzantine and the Umayyad periods. In passing from Byzantine to Umayyad control the Balqa' underwent a process of transformation, especially in regards to political matters. But the more important trend was one of continuity, even the transfer of political power from the Byzantine bureaucracy to Arab notables was but the culmination of a trend which had begun with the rise of the Ghassanids in the previous century.

No description available.

Metal oxides are a very important class of materials with a wide range of photovoltaic applications. Transparent conducting oxides (TCOs) are the primary front contact materials used in thin film solar cells. Identification of methods for reducing the resistivity of these materials would have significant benefits. Development of p-type TCOs would provide alternative back contact materials and could enable further development of technologies such as bifacial, window and multijunction cells. A series of studies into these areas is presented in this work. Aluminium doped zinc oxide (AZO) is a well-known n-type TCO consisting entirely of Earth-abundant materials. Targets were manufactured from AZO powder, which was synthesised using a patented emulsion detonation process developed by Innovnano S.A. All films showed good optical transmission. Resistivity was found to decrease with both increasing time and temperature up to 300 degree C. Temperatures above 300 degree C were found to be detrimental to film formation, with increasing amounts of damage to the crystal structure and consequent increases in the resistivity. The effect of alloying molybdenum oxide with molybdenum nitride through reactive sputtering in a mixed oxygen-nitrogen atmosphere was investigated. All alloys were found to show p-type behaviour. Resistivity was found to improve with increased nitrogen content, in contrast to optical transmission, which reduced. A selection of compositions were deposited onto CdTe cells as back contacts. These cells showed an increase in efficiency with increasing nitrogen content. Work function was found to increase with increasing oxygen content, but all work functions were low. Resistivity was shown to correlate strongly with efficiency, caused by a corresponding increase in cell voltage. This implies that to form an ohmic contact on CdTe with p-type materials, work function may be less important than resistivity. The copper oxides are p-type, but uses are limited by the narrow band gaps. Cupric oxide was chosen for investigation and for alloying with other oxides with the aim of increasing the band gap. It was found that temperature and deposition environment have significant impacts on sputtered cupric oxide (CuO) films, with low temperatures and high oxygen environments producing the lowest resistivities. Extrinsic sodium doping was found to reduce the resistivity by up to four orders of magnitude. High oxygen content sodium-doped films were found to have carrier concentrations two orders of magnitude higher than that of indium tin oxide.

No description available.