Poe and the short-story

Thesis (M.A.)--Boston Universit

Alien Registration- Lesuer, Margaret A. (Calais, Washington County)

https://digitalmaine.com/alien_docs/2597/thumbnail.jp

Diffusion of tin from TEC-8 conductive glass into mesoporous titanium dioxide in dye sensitized solar cells

The photoanode of a dye sensitized solar cell is typically a mesoporous titanium dioxide thin film adhered to a conductive glass plate. In the case of TEC-8 glass, an approximately 500 nm film of tin oxide provides the conductivity of this substrate. During the calcining step of photoanode fabrication, tin diffuses into the titanium dioxide layer. Scanning Electron Microscopy and Electron Dispersion Microscopy are used to analyze quantitatively the diffusion of tin through the photoanode. At temperatures (400 to 600 °C) and times (30 to 90 min) typically employed in the calcinations of titanium dioxide layers for dye sensitized solar cells, tin is observed to diffuse through several micrometers of the photoanode. The transport of tin is reasonably described using Fick\u27s Law of Diffusion through a semi-infinite medium with a fixed tin concentration at the interface. Numerical modeling allows for extraction of mass transport parameters that will be important in assessing the degree to which tin diffusion influences the performance of dye sensitized solar cells

Materials science and engineering

During FY-96, work within the Materials Science and Engineering Thrust Area was focused on material modeling. Our motivation for this work is to develop the capability to study the structural response of materials as well as material processing. These capabilities have been applied to a broad range of problems, in support of many programs at Lawrence Livermore National Laboratory. These studies are described in (1) Strength and Fracture Toughness of Material Interfaces; (2) Damage Evolution in Fiber Composite Materials; (3) Flashlamp Envelope Optical Properties and Failure Analysis; (4) Synthesis and Processing of Nanocrystalline Hydroxyapatite; and (5) Room Temperature Creep Compliance of Bulk Kel-E

Severe plastic deformation through adiabatic shear banding in Fe-C steels

Severe plastic deformation is observed within adiabatic shear bands in iron-carbon steels. These shear bands form under high strain rate conditions, in excess of 1000 s{sup -1}, and strains in the order 5 or greater are commonly observed. Studies on shear band formation in a ultrahigh carbon steel (1.3%C) are described in the pearlitic condition. A hardness of 11.5 GPa (4600 MPa) is obtained within the band. A mechanism is described to explain the high strength based on phase transformation to austenite from adiabatic heating resulting from severe deformation. Rapid re-transformation leads to an ultra-fine ferrite grain size containing carbon principally in the form of nanosize carbides. It is proposed that the same mechanism explains the ultrahigh strength of iron-carbon steels observed in ball-milling, ball drop tests and in severely deformed wires

Laminated metal composite formed from low flow stress layers and high flow stress layers using flow constraining elements and method of making same

This invention relates to a laminated metal composite, comprising alternating layers of low flow stress material and high flow stress material, and formed using flow constraining elements around each low flow stress layer; and a method of making same. A composite is a combination of at least two chemically distinct materials with a distinct interface separating the two materials. A metal matrix composite (MMC) is a composite material composed of a metal and a nonmetallic reinforcing agent such as silicon carbide (SiC) or graphite in continuous or discontinuous fiber, whisker, or discrete particulate form. A laminate is a material composed of several bonded layers. It is possible to have a laminate composed of multi-layers of a single type of material bonded to each other. However, such a laminate would not be considered to be a composite. The term {open_quotes}laminated metal composite{close_quotes} (LMC), as used herein, is intended to include a structural material composed of: (1) layers of metal or metal alloys interleaved with (2) a different metal, a metal alloy, or a metal matrix composite (MMC) containing strengthening agents

Perceptions of a program approach to virtual laboratory provision for analytical and bioanalytical sciences

When teaching chemistry and biosciences courses to undergraduate and postgraduate students, laboratory experience is a crucial requirement for skills development. Due to COVID-19 related closure of laboratories it became critical to replace that experience with virtual delivery. Through carefully designed learning experiences it is possible for students to gain skills such as experimental design, problem solving, record keeping and data analysis. Here we present a coordinated approach to the design of laboratory classes for a cross discipline postgraduate program. Virtual laboratory classes, using freely available web-based simulators, were run in a synchronous manner with pre lab briefing and post lab data analysis sessions. The laboratory scripts were developed using a command prompt design: [Do][Explore][Act] framework, which is intended to provide students with a guided approach to using the simulator while in a remote setting. The intended outcome was to develop student’s record keeping and understanding of the scientific principles of the instrumentation through practical experimentation. Student experience of the virtual laboratory provision was surveyed via a mix method approach, with an 81% response rate. Satisfaction with the virtual labs was high (68%), with students agreeing the laboratories contained the appropriate balance of challenge and support. The command prompts were thought to be a very useful way to structure a lab script (77% agreement) and many suggested this approach should be kept for future laboratory use. Students self-identified the main skills learnt as being laboratory bookkeeping, analyzing data, problem solving and use of equipment