Square character degree graphs yield direct products

If $G$ is a solvable group, we take $\Delta (G)$ to be the character degree graph for $G$ with primes as vertices. We prove that if $\Delta (G)$ is a square, then $G$ must be a direct product

Highly selective hydrogenation of furfural over supported Pt nanoparticles under mild conditions

The selective liquid phase hydrogenation of furfural to furfuryl alcohol over Pt nanoparticles supported on SiO₂, ZnO, γ-Al2O₃, CeO₂ is reported under extremely mild conditions. Ambient hydrogen pressure, and temperatures as low as 50 °C are shown sufficient to drive furfural hydrogenation with high conversion and >99% selectivity to furfuryl alcohol. Strong support and solvent dependencies are observed, with methanol and n-butanol proving excellent solvents for promoting high furfuryl alcohol yields over uniformly dispersed 4 nm Pt nanoparticles over MgO, CeO₂ and γ-Al₂O₃. In contrast, non-polar solvents conferred poor furfural conversion, while ethanol favored acetal by-product formation. Furfural selective hydrogenation can be tuned through controlling the oxide support, reaction solvent and temperature

Nanoengineered polymer architectures for antimicrobial medical applications: Novel additives

Silver is a clinically important, broad spectrum antibacterial, whose use extends back over several millennia. Its potent antibacterial activity, range of susceptible microorganisms, and lack of developed resistances, elevate silver as an exciting weapon in the fight against hospital acquired infections and so-called ‘superbugs’. The active, ionic form is efficacious at very low concentrations, thus controlling release rates offers potential durable, non-specific, antibacterial medical devices. This thesis examines a number of inorganic systems as potential slow-release, antibacterial silver nanocomposites for incorporation into polyurethane foam wound dressings. A range of silver core-silica shell nanocomposites were synthesised with tuneable dimensions, with porosity introduced into the silica shells, via base-etching or surfactant-templating producing disordered or ordered architectures respectively. An alternative system based on mesoporous SBA-15 silica was also investigated, which was employed as a scaffold for subsequent multilayer titania functionalisation, onto which mixed silver/silver carbonate nanoparticles were subsequently deposited. Detailed characterisation allowed fundamental structural-function relationships for silver dissolution kinetics and their associated impact upon antibacterial activity towards Gram-positive and Gram-negative bacteria including methicillin-resistant Staphylococcus aureus. Silver ion release rates are inversely proportional to silver crystallite size, with further governance via shell thickness and mesoporosity achievable in core shell systems. The intrinsic antibacterial activity of titania coated SBA-15 further enhances performance, independent of silver, whilst support macropore introduction increases silver particle dispersion. Antibacterial prowess of all materials demonstrates a strong activity correlation with dissolution kinetics, evidencing up to seven-fold logarithmic reductions in the bacterial concentrations within four hours. Materials were potent for > 24 hours, with the reverse micelle core-shell formulation showing continuous activity over a 14 day period. Comparative benchmarking indicates mesoporous silver core-silica shell architectures as promising candidates due to antibacterial longevity, manufacturing simplicity and cost, with their hydrophilic nature and small dimensions rendering them amenable to incorporation into compatible polyurethane foams

Restructuring the urban neighborhood : the dialogue between image and ideology in Phoenix Hill, Louisville, Kentucky

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1980.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Includes bibliographical references.This thesis addresses the problems of restructuring the urban neighborhood as specifically applied to the Phoenix Hill community in Louisville, Kentucky. Theory and concepts are briefly presented as a basis for design proposals for housing and open space. The first chapter introduces the destructure-restructure concept and discusses its social and political consequences when applied at the neighborhood scale: urban renewal produces changing ways of life for existing residents, but are they desired changes? Whose beliefs, ideas and aspirations are built into the renewed urban environment? Whose way of life becomes embodied in physical form? This leads to a discussion relating the images a designer projects in the environment to the ideology represent . The second chapter presents an historical reading of the social and physical context of the Phoenix Hill area, discussing how the interests of various social structures (or ideologies) were built into the physical structure (or image) of the environment. The third chapter presents the Urban Renewal Plan now being prepared for Phoenix Hill--an inner city neighborhood with a predominantly low-income black population. An analysis of the planning process interprets which social interests are represented in the physical plan: community development for one group may threaten community destruction another. In this case, transplanting suburban images and ideology back to the city may mean the end of a way of life for Phoenix Hill's existing residents. The final chapter offers some alternate images of what Phoenix Hill could be. Designs for housing and community open space follow a statement of planning objectives and redevelopment strategies. The work draws upon lessons taken from the reading of the historical development of the neighborhood. The design activity focuses on a key block at the center of the various institutional forces operating in Phoenix Hill. The model for the block structure relates to the existing pattern by confining buildings close to the street edge while leaving the interior of the block free. A new pattern of community open space maintains this block center as a two-acre park for the common enjoyment of all residents. This model for Phoenix Commons is extended to other blocks to form a continuous greenway connecting the cultural and work activity of downtown Louisville with the recreation and relaxation found in Cherokee Park--a major Olmstead-designed park just beyond the inner city's edge. The housing strategy emphasizes rehabilitation of existing sound buildings and new in fill construction relating to the historic nineteenth century fabric. In approaching the maximum density allowable under the Urban Renewal Plan, the historic house types are transformed to a new urban housing form: the infill dwellings combine the spacious, light-filled qualities of historic atrium houses with the energy-and material-saving aspects of attached townhouses. The units have been designed with consideration of implementation strategies that maintain lower - income residents as part of a mixed-income development and allows them to participate in the benefits of cooperative homeownership.by Mark Andrew Isaacs.M.Arch

Beyond the simple Proximity Force Approximation: geometrical effects on the non-retarded Casimir interaction

We study the geometrical corrections to the simple Proximity Force Approximation for the non-retarded Casimir force. We present analytical results for the force between objects of various shapes and substrates, and between pairs of objects. We compare the results to those from more exact numerical calculations. We treat spheres, spheroids, cylinders, cubes, cones, and wings; the analytical PFA results together with the geometrical correction factors are summarized in a table.Comment: 18 pages, 19 figures, 1 tabl

Is Photocatalysis the Next Technology to Produce Green Hydrogen to Enable the Net Zero Emissions Goal?

Energy security concerns require novel greener and more sustainable processes, and Paris Agreement goals have put in motion several measures aligned with the 2050 roadmap strategies and net zero emission goals. Renewable energies are a promising alternative to existing infrastructures, with solar energy one of the most appealing due to its use of the overabundant natural source of energy. Photocatalysis as a simple heterogeneous surface catalytic reaction is well placed to enter the realm of scaling up processes for wide scale implementation. Inspired by natural photosynthesis, artificial water splitting's beauty lies in its simplicity, requiring only light, a catalyst, and water. The bottlenecks to producing a high volume of hydrogen are several: Reactors with efficient photonic/mass/heat profiles, multifunctional efficient solar-driven catalysts, and proliferation of pilot devices. Three case studies, developed in Japan, Spain, and France are showcased to emphasize efforts on a pilot and large-scale examples. In order for solar-assisted photocatalytic H2 to mature as a solution, the aforementioned bottlenecks must be overcome for the field to advance its technology readiness level, assess the capital expenditure, and enter the market

Carbon nitride as a ligand: edge-site coordination of ReCl(CO)3-fragments to g-C3 N4

IR spectroscopy and model structural studies show binding of ReCl(CO) 3-fragments to carbon nitride (g-C 3N 4) occurs via κ 2 N,N′ bidentate coordination