Thermal properties of concrete with different Swedish aggregate materials

Earlier studies show that different concrete aggregates have different thermal properties, and from this an idea to optimize thermal properties of concrete was developed. The purpose of this master thesis is to investigate thermal properties of concrete so additional costs and negative environmental impacts can be minimized. Measurements of thermal properties of different Swedish aggregates from existing quarries were investigated. It will also study if the thermal properties affect ther thermal expansion of concrete. The experimental study in this work was done in laboratory conditions. Preparation studies that were made before casting concrete were sieving aggregates, density of aggregates and moisture content. While the concrete was fresh standard tests such as slump, air-content and density of fresh concrete were made. When the concrete was 28 days old compressive cube strength and thermal expansion measurement were executed. The thermal properties (thermal conductivity, volumetric heat capacity and thermal diffusivity) were measured on aggregates and concrete cubes with the instrument Hot Disk 2500-S. The results show that the minerals quartz and magnetite have significantly different thermal properties than the other studied aggregates/concretes. The aggregate/concrete with high amount quartz mineral has high thermal conductivity and diffusivity. The aggregates/concrete with magnetite has high thermal conductivity and volumetric heat capacity. The other aggregates and concretes have similar thermal properties. The thermal expansion coefficients have similar values (12.6-15.5∙ 1 /⁰C) for different aggregates, and it was not possible to see if there was a correlation between them and the thermal properties. Thus was the value of thermal expansion coefficient in a range that is normal for concrete. The thermal shock resistance is dependent of the thermal conductivity, thermal expansion coefficient, fracture strength and elastic modulus. The concretes with high thermal conductivity also had high thermal shock resistance whereas so such concrete should better resist rapid temperature changes. The conclusions that can be drawn from this work are that the thermal properties of the aggregates will be reflected in the properties of the concrete. For both thermal conductivity and heat capacity the values for the dry concretes (RH 10-30%) were about 40-70% of the values of the aggregates. Note that this conclusion only applies for thermal conductivity and heat capacity and does not apply on thermal diffusivity, since diffusivity is the ratio of conductivity and capacity it will be similar in the concrete. In this study only two aggregates significantly affected the thermal properties: quartz has high thermal conductivity and diffusivity and magnetite rock has high thermal conductivity and heat capacity. Another conclusion from this study was high thermal conductivity also give high thermal shock resistance, where the concrete resist rapid temperature changes better

Synthesis of 6-thiosubstituted pentacenes and study of an unexpected photorearrangement of 6-phenylthiopentacene dimer

Two new monosubstituted pentacene derivatives, 6-phenylthiopentacene, 26, and 6-acetylthiopentacene, 27, have been prepared using a dehydrogenative aromatization and elimination reaction that utilizes 1,8-diazabicycloundec-7-ene (DBU) as reagent. Although many disubstituted pentacenes have been synthesized and characterized, monosubstituted pentacenes have received much less attention. While studying the photodegradation of 26 under ambient light and air conditions, an unexpected transformation to 6,13-bis(phenylthio)pentacene, 32, was observed. The transformation requires short wavelength (254 nm) UV irradiation. Through a combined experimental and computational study, we have identified this transformation as a multi-step intramolecular process initiated by the photoexcitation of the endo anti dimer of 26. The photoexcited dimer undergoes an intramolecular acid-base reaction which involves two proton transfers and nucleophilic substitution to form the rearranged photodimer which upon dissociation yields bisadduct 32. Using 254 nm light and a quartz reaction vessel, bisadduct 32 has been isolated in 20% yield from monoadduct 26

A decade of dental education: Faculty of Dentistry

Published on the occasion of the 10th anniversary of the faculty.Incudes bibliographical references.published_or_final_versionConservative dentistry: achievements and perspectives 47Congratulations Wang, Gungwu Wang, Gungwu viiForeword Wei, Stephen H.Y. Wei, Stephen H.Y. ixAcknowledgements Wei, Stephen H.Y. Wei, Stephen H.Y. xiThe Prince Philip Dental Hospital 1Departments and units: a decade of activities and progressStudents' life in the faculty 151Alumni 155Faculty of Dentistry - dental graduates 1985-1992 157The next decade and beyond - some prospects in dentistry 175Brief history of the Faculty of Dentistry 1Administration and governance 4Other services 7Children's dentistry and orthodontics: achievemnets and perspective 13Oral and maxillofacial survey: achievements and perspectives 69Periodontology and public health: achievements and perspectives 95Prosthetic dentistry: achievements and perspectives 113Dental technology unit 125Dental materials science unit: achievements and perspectives 131Oral Biology Unit: achievements and perspectives 139Optimizing adhesion with mineralized dental tissues Gwinnett, A. John Gwinnett, A.John 177Conservative approach to esthetic dentistry Suzuki, M. Mike Suzuki, M. Mike 183The wonderful world of glass ionomer cements Mount, Graham J. Mount, Graham J. 189Biocompatibility of dental materials Smith, Dennis C. Smith, Dennis C. 197Esthetic implant restorations Lewis, Steven Lewis, Steven 203Chemicals in the treatment of periodontal diseases Gjermo, Per Gjermo, Per 21

Library as Scholarly Publishing Partner: Keys to Success

Many academic libraries are looking at new ways to add value when they deliver services to faculty, and one potential area where the library can provide new services is in partnering with academic staff to support the dissemination of faculty research. Librarians have traditionally helped faculty researchers at the beginning of the research cycle, with the discovery and delivery of information sources. However, they are now playing a role at the end of the research cycle, providing services that support scholarly publishing. This paper examines library participation in faculty-led publishing ventures. In particular, it explores the value that smaller research libraries can provide to faculty editors through journal hosting, which will be analysed through an examination of the successful migration of the Australian Journal of Teacher Education, a faculty-administered journal at Edith Cowan University in Perth, Western Australia, to the University’s institutional repository. This transition provided library staff members at Edith Cowan University opportunities to develop new knowledge and skills in journal publishing, while meeting the journal’s need for a better way to manage a growing influx of article submissions. The resultant faculty-library partnership enabled more effective management of the journal and has contributed to its growing success. The evaluative framework developed to enable assessment of the success of this journal’s transition can help other libraries demonstrate the success of their own journal hosting ventures

Structural and Physical Properties of CaFe4As3 Single Crystals

We report the synthesis, and structural and physical properties of CaFe4As3 single crystals. Needle-like single crystals of CaFe4As3 were grown out of Sn flux and the compound adopts an orthorhombic structure as determined by X-ray diffraction measurements. Electrical, magnetic, and thermal properties indicate that the system undergoes two successive phase transitions occurring at TN1 ~ 90 K and TN2 ~ 26 K. At TN1, electrical resistivities (\rho(b) and \rho(ac)) are enhanced while magnetic susceptibilities (\chi(b) and \chi(ac)) are reduced in both directions parallel and perpendicular to the b-axis, consistent with the scenario of antiferromagnetic spin-density-wave formation. At TN2, specific heat reveals a slope change, and \chi(ac) decreases sharply but \chi(b) has a clear jump before it decreases again with decreasing temperature. Remarkably, both \rho(b) and \rho(ac) decrease sharply with thermal hysteresis, indicating the first-order nature of the phase transition at TN2. At low temperatures, \rho(b) and \rho(ac) can be described by {\rho} = {\rho}0 + AT^\alpha ({\rho}0, A, and {\alpha} are constants). Interestingly, these constants vary with applied magnetic field. The ground state of CaFe4As3 is discussed.Comment: 15 pages, 8 figures, Submitted to Physical Review