THE USE OF LIFE-CYCLE ANALYSIS TO REDUCE THE ENVIRONMENTAL IMPACT OF MATERIALS IN MANUFACTURING

This thesis is composed of three life-cycle analysis (LCA) studies of manufacturing to determine cumulative energy demand (CED) and greenhouse gas emissions (GHG). The methods proposed could reduce the environmental impact by reducing the CED in three manufacturing processes. First, industrial symbiosis is proposed and a LCA is performed on both conventional 1 GW-scaled hydrogenated amorphous silicon (a-Si:H)-based single junction and a-Si:H/microcrystalline-Si:H tandem cell solar PV manufacturing plants and such plants coupled to silane recycling plants. Using a recycling process that results in a silane loss of only 17 versus 85 percent, this results in a CED savings of 81,700 GJ and 290,000 GJ per year for single and tandem junction plants, respectively. This recycling process reduces the cost of raw silane by 68 percent, or approximately $22.6 and$79 million per year for a single and tandem 1 GW PV production facility, respectively. The results show environmental benefits of silane recycling centered around a-Si:H-based PV manufacturing plants. Second, an open-source self-replicating rapid prototype or 3-D printer, the RepRap, has the potential to reduce the environmental impact of manufacturing of polymer-based products, using distributed manufacturing paradigm, which is further minimized by the use of PV and improvements in PV manufacturing. Using 3-D printers for manufacturing provides the ability to ultra-customize products and to change fill composition, which increases material efficiency. An LCA was performed on three polymer-based products to determine the CED and GHG from conventional large-scale production and are compared to experimental measurements on a RepRap producing identical products with ABS and PLA. The results of this LCA study indicate that the CED of manufacturing polymer products can possibly be reduced using distributed manufacturing with existing 3-D printers under 89% fill and reduced even further with a solar photovoltaic system. The results indicate that the ability of RepRaps to vary fill has the potential to diminish environmental impact on many products. Third, one additional way to improve the environmental performance of this distributed manufacturing system is to create the polymer filament feedstock for 3-D printers using post-consumer plastic bottles. An LCA was performed on the recycling of high density polyethylene (HDPE) using the RecycleBot. The results of the LCA showed that distributed recycling has a lower CED than the best-case scenario used for centralized recycling. If this process is applied to the HDPE currently recycled in the U.S., more than 100 million MJ of energy could be conserved per annum along with significant reductions in GHG. This presents a novel path to a future of distributed manufacturing suited for both the developed and developing world with reduced environmental impact. From improving manufacturing in the photovoltaic industry with the use of recycling to recycling and manufacturing plastic products within our own homes, each step reduces the impact on the environment. The three coupled projects presented here show a clear potential to reduce the environmental impact of manufacturing and other processes by implementing complimenting systems, which have environmental benefits of their own in order to achieve a compounding effect of reduced CED and GHG

Model to describe the mode I fracture of steel fiber reinforced ultra-high performance concrete

Ultra-high performance fiber reinforced concrete (UHPFRC) has arisen from the implementation of a variety of concrete engineering and materials science concepts developed over the last century. This material offers superior strength, serviceability, and durability over its conventional counterparts. One of the most important differences for UHPFRC over other concrete materials is its ability to resist fracture through the use of randomly dispersed discontinuous fibers and improvements to the fiber-matrix bond. Of particular interest is the materials ability to achieve higher loads after first crack, as well as its high fracture toughness. In this research, a study of the fracture behavior of UHPFRC with steel fibers was conducted to look at the effect of several parameters related to the fracture behavior and to develop a fracture model based on a non-linear curve fit of the data. To determine this, a series of three-point bending tests were performed on various single edge notched prisms (SENPs). Compression tests were also performed for quality assurance. Testing was conducted on specimens of different cross-sections, span/depth (S/D) ratios, curing regimes, ages, and fiber contents. By comparing the results from prisms of different sizes this study examines the weakening mechanism due to the size effect. Furthermore, by employing the concept of fracture energy it was possible to obtain a comparison of the fracture toughness and ductility. The model was determined based on a fit to P-w fracture curves, which was cross referenced for comparability to the results. Once obtained the model was then compared to the models proposed by the AFGC in the 2003 and to the ACI 544 model for conventional fiber reinforced concretes

Towards Trigonal Prismatic Hexanuclear Copper Complexes For Catalytic Water Oxidation

Our planet is running out of energy resources and traditional renewables are not easily transported nor will be sufficient to cover the void left by fossil fuels. Therefore, a new energy storage system needs to be adopted. The medium with highest energy density that is readily available is hydrogen from water. However, to access hydrogen, water needs to be oxidized and water oxidation catalysts (WOCs) will be required for widespread adoption. In pursuit of WOCs, several hexauclear copper complexes were synthesized and characterized, including the isolation and characterization of a mixed-valent Cu6 (formally, CuII5CuIII) complex. Furthermore, early in the research, several novel coordination polymers (CPs) were serendipitously synthesized. This dissertation is divided into three major parts: (i) A series of trigonal prismatic Cu6-pyrazolato complexes (Cu6) form a unique arrangement of two O2- ions in a favorable position to form an O-O bond without much external influence. The Cu6 complexes undergo two reversible one-electron oxidations and a structurally characterized one-electron oxidized mixed-valent complex displays an O···O distance ~0.3 Å closer than the homovalent compound, which highlights the propensity of the system towards O-O bond formation. Spectroscopic findings and DFT calculations on the electronic structure of the mixed-valent Cu6-complex are reported. The results support the hypothesis that a variation of a Cu6 motif could function as a water oxidation catalyst. (ii) Three new coordination polymers containing trinuclear Cu(II)-4-formyl pyrazolato units connected by formyl group coordination were prepared and the crystal structures are reported: a 1D polymer formed by linking secondary building units (SBUs) and two 3D polymers with novel topologies consist of 14-nodal 3842,54-c and 3-nodal 3,3,4-c nets, respectively. (iii) Two new motifs of Cu6-pyrazolato complexes were prepared. One motif has two pyrazolato bridges between the trinuclear copper subunits with a µ4-Cl situated inside the open cage, and the other has the subunits bridged by a single pyrazolato ligand. Variable low-temperature NMR and magnetic studies were conducted. And for the first time, far-infrared spectroscopy studies were used to determine the characteristic absorptions of various coordination bonds in copper pyrazolate complexes

Assessment of long-term remission of acromegaly following surgery

Journal ArticleObject. The criteria for remission of acromegaly following transsphenoidal adenoma resection are in evolution. In the present study the authors evaluate the utility of predicting long-term remission by reference to a single fasting growth hormone (GH) level on the 1st postoperative day. Methods. A retrospective analysis was conducted on 181 patients with acromegaly who underwent transsphenoidal resection between 1973 and 1990 and completed a 5-year follow-up period. Fasting serum GH levels were obtained in all patients on the 1st postoperative day in the absence of exogenous glucocorticoids. All patients participated in a follow-up evaluation lasting at least 5 years, which included measurements of serum insulin-like growth factor-I (IGF-I) levels as an index of acromegalic activity. Among the 181 patients, GH levels ranged from 0 to 8 ng/ml in 131 (72%) on the 1st postoperative day, suggesting biochemical remission. This group included 107 (84%) of the 127 patients with microadenomas, but only 24 (44%) of the 54 with macroadenomas. Nevertheless, 15 (11%) of the 131 patients who initially had attenuated GH levels displayed recurrent acromegaly within the first 2 years (with elevated levels of IGF-I in all cases, and abnormalities appearing on magnetic resonance images in nine cases). Only one of 116 patients in whom the initial postoperative GH level was lower than 2 ng/ml experienced a recurrence, whereas 14 (93%) of the 15 patients with postoperative GH levels between 2.2 and 8 ng/ml subsequently displayed biochemical evidence of acromegaly. Conclusions. The findings indicate that a fasting morning serum GH level lower than 2 ng/ml on the 1st postoperative day portends long-term biochemical remission of acromegaly, whereas higher levels are a significant marker for recurrent disease

The Business of Commemoration: A Comparative Study of Italian Catacombs

Late antique funerary workers shaped the material forms of burial and commemoration and played influential roles in the social world of the cemetery. In this dissertation, I present a social-historical inquiry into their working practices and interactions with their patrons. In particular, I examine the work of gravediggers, painters, and engravers who labored in catacombs—the massive subterranean necropoleis that developed outside some Italian urban centers in the third to sixth centuries CE. The catacombs of Domitilla (Rome), San Gennaro (Naples), and San Giovanni (Syracuse) furnish the large corpora of architecture, painting, and inscriptions through which I study the late antique funerary industry, using methods drawn from classical archaeology, art history, and philology. Throughout I argue for the application of “network thinking” to the study of these poorly understood workers: where we cannot trace the movements of an individual, we should look for workshops, communities, and other “collective agents” accomplishing funerary labor through social interaction. The first chapter provides context for this inquiry by outlining its theoretical and methodological approaches, major sources, and datasets. Chapter 2 addresses the Roman fossores—the gravediggers who excavated and managed catacombs—and reviews longstanding debates about the extent of the Church’s control over their work. Chapter 3 proposes criteria for workshop attribution in catacomb painting by systematically examining painting of the so-called “red and green linear style” in Naples, a style often overlooked in favor of the figural types employed in catacomb decoration. Chapter 4 approaches engravers from two directions: quantitative analysis of a large epigraphic corpus to find workshop-specific patterns in the use of words and images, and an examination of a small group of inscribed plaques as artifacts, in order to uncover the working practices and trade networks of engravers. Chapter 5 considers the work of fossores, painters, and engravers in the social contexts of catacombs, attempting to chart these workers’ interactions with their patrons, with each other, and with members of non-funerary professions. This interdisciplinary project takes a worker-centered approach to funerary labor in late antiquity, seeking to shed light on the social contexts of cultural production in the catacombs.PHDClassical Art & ArchaeologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/138452/1/jkreiger_1.pd

Semiclassical wave equation and exactness of the WKB method

The exactness of the semiclassical method for three-dimensional problems in quantum mechanics is analyzed. The wave equation appropriate in the quasiclassical region is derived. It is shown that application of the standard leading-order WKB quantization condition to this equation reproduces exact energy eigenvalues for all solvable spherically symmetric potentials.Comment: 13 page

Age of smoking initiation and risk of breast cancer in a sample of Ontario women

<p>Abstract</p> <p>Objectives</p> <p>To examine the association between time of smoking initiation and both the independent and joint effects of active and passive tobacco smoke exposure and the risk of breast cancer in a sample of Ontario women.</p> <p>Methods</p> <p>Data from two large population-based case-control studies conducted among Ontario women aged 25–75 years were combined for analysis (n = 12,768).</p> <p>Results</p> <p>Women who had ever smoked and were exposed to passive smoke had a significant increased risk of breast cancer (OR 1.13, 95%CI 1.01–1.25). A significant increased risk was also observed among women who initiated smoking: at age 26 or older (OR 1.26, 95%CI 1.03–1.55); more than five years from menarche (OR 1.26, 95%CI 1.12–1.42); and, after their first live birth (OR 1.25, 95%CI 1.02–1.52).</p> <p>Conclusion</p> <p>The results suggest that women who initiate smoking at an older age are at an increased risk of breast cancer.</p

The Viability and Simplicity of 3D-Printed Construction: A Military Case Study

In November 2019, U.S. Marines, Air Force, and Army Corps of Engineers personnel demonstrated the viability and simplicity of three-dimensionally (3D)-printed construction in a controlled environment at the U.S. Army Engineer Research and Development Center—Construction Engineering Research Laboratory in Champaign, Illinois. The tri-service exercise spanned three days and culminated in the construction of three 1 m × 1 m × 1 m (3 ft × 3 ft × 3 ft) concrete dragon’s teeth (square pyramid military fortifications used to defend against tanks and armored vehicles) and several custom-designed objects. The structural components were printed using a custom-built, gantry-style printer called ACES Lite 2 and a commercially available, proprietary mortar mix. This paper examines the viability of using 3D-printed construction in remote, isolated, and expeditionary environments by considering the benefits and challenges associated with the printing materials, structural design, process efficiency, labor demands, logistical considerations, environmental impact, and project cost. Based on the results of this exercise, 3D-printed construction was found to be faster, safer, less labor-intensive, and more structurally efficient than conventional construction methods: the dragon’s teeth were printed in an average of 57 min each and required only two laborers. However, the use of commercially procured, pre-mixed materials introduced additional cost, logistical burden, and adverse environmental impact as compared to traditional, on-site concrete mixing and production. Finally, this paper suggests future applications and areas of further research for 3D-printed construction