abstract: The built environment is responsible for a significant portion of global waste generation. Construction and demolition (C&D) waste requires significant landfill areas and costs billions of dollars. New business models that reduce this waste may prove to be financially beneficial and generally more sustainable. One such model is referred to as the “Circular Economy” (CE), which promotes the efficient use of materials to minimize waste generation and raw material consumption. CE is achieved by maximizing the life of materials and components and by reclaiming the typically wasted value at the end of their life. This thesis identifies the potential opportunities for using CE in the built environment. It first calculates the magnitude of C&D waste and its main streams, highlights the top C&D materials based on weight and value using data from various regions, identifies the top C&D materials’ current recycling and reuse rates, and finally estimates a potential financial benefit of $3.7 billion from redirecting C&D waste using the CE concept in the United States. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2019

The U.N. projects the world population to reach nearly 10 billion people by 2050, which will cause demand for manufactured goods to reach unforeseen levels. In order for us to produce the goods to support an equitable future, the methods in which we manufacture those goods must radically change. The emerging Circular Economy (CE) concept for production systems has promised to drastically increase economic/business value by significantly reducing the world’s resource consumption and negative environmental impacts. However, CE is inherently limited because of its emphasis on recycling and reuse of materials. CE does not address the holistic changes needed across all of the fundamental elements of manufacturing: products, processes, and systems. Therefore, a paradigm shift is required for moving from sustainment to sustainability to “produce more with less” through smart, innovative and transformative convergent manufacturing approaches rooted in redesigning next generation manufacturing infrastructure. This PhD research proposes the Helical Economy (HE) concept as a novel extension to CE. The proposed HE concepts shift the CE’s status quo paradigm away from post-use recovery for recycling and reuse and towards redesigning manufacturing infrastructure at product, process, and system levels, while leveraging IoT-enabled data infrastructures and an upskilled workforce. This research starts with the conceptual overview and a framework for implementing HE in the discrete product manufacturing domain by establishing the future state vision of the Helical Economy Manufacturing Method (HEMM). The work then analyzes two components of the framework in detail: designing next-generation products and next-generation IoT-enabled data infrastructures. The major research problems that need to be solved in these subcomponents are identified in order to make near-term progress towards the HEMM. The work then proceeds with the development and discussion of initial methods for addressing these challenges. Each method is demonstrated using an illustrative industry example. Collectively, this initial work establishes the foundational body of knowledge for the HE and the HEMM, provides implementation methods at the product and IoT-enabled data infrastructure levels, and it shows a great potential for HE’s ability to create and maximize sustainable value, optimize resource consumption, and ensure continued technological progress with significant economic growth and innovation. This research work then presents an outlook on the future work needed, as well as calls for industry to support the continued refinement and development of the HEMM through relevant prototype development and subsequent applications.

Background – Circular business models, CBMs, are an emerging topic of interest within the textile and clothing, T&C, sector. They provide a new framework to tackle current environmental and social issues by redesigning a linear model previously base on the assumption of endless availability of fossil fuels and other natural resources. CBMs change these underlying assumptions in order to be regenerative and waste-less. A company´s knowledge has to be aligned with the overarching paradigm and assumptions that guide the business model, hence, the process of creating new knowledge to sustain this shift, appears to be essential. Knowledge creation enables businesses to continuously adapt to new contexts and prevent them from becoming obsolete. As such, it constitutes an enabler to develop the internal capabilities of companies to innovate. Purpose - This study is focused on understanding how knowledge is created within T&C companies in the shift from a linear business model to a circular one. It is of interest for the study to uncover the ways in which knowledge about circularity is created and translated into business practices. Further, it also expects to explore the companies’ main internal barriers identified in this process. Methodology – The research was conducted through a single case study with an abductive approach, building on the theoretical perspective of Nonaka and Takeuchi’s knowledge creation theory and the SECI model for knowledge conversion. Semi-structured interviews with Dutch denim company employees were the basis for collecting primary data, supplemented by secondary data gathered through archival review. The data was analysed qualitatively through thematic content analysis. Findings – Results show that knowledge creation is enabled by personal motivation, company focus on circularity and long-lasting business relationships. Several knowledge creation practices related to the dimensions of socialisation, externalisation, combination and internalisation are identified, while different levels of process and knowledge complexity can be observed within each dimension. Internal barriers hindering circular knowledge creation relate to the complexity of circular concepts, individuals´ time, personal interest and previous knowledge on the topic. System-oriented internal barriers relate to finance, scale and company focus. Further, the role of regulations, as an external system-oriented barrier, is considered of relevance for this research. Practical implications & Research limitations – This thesis creates new insights into a relatively unexplored area, knowledge creation processes in the context of CBMs. Further the specific delimitation to the denim segment within the T&C sector, shares experience and guidance with practical implications for knowledge management, from companies within a segment which has a high degree of product and process innovation compared to other T&C segments.

Textilindustrin är en av världens mest förorenade industrier idag. Fast fashion företag uppmuntrar konsumenter till ökade köp genom sina låga priser. Förr handlade människor nya kläder vid behov, till skillnad från idag då många konsumerar efter begär. Att textilindustrin har stor påverkan på miljön är många väl medvetna om, men för att de ska kunna ske en förändring måste både konsumenter och företag vidta de åtgärder som krävs. Syftet med denna studie har varit att undersöka slutfasen i den textila värdekedjan. I denna avhandling kommer fenomenet upcycling att studeras och ifrågasättas som en lösning till textilavfall. Upcycling innebär att förlänga livet på ett förbrukat plagg, vilket är en vidareutveckling på en cirkulär ekonomi. Under denna studie har all kontakt med branschfolk varit inom Sverige och arbetet har huvudsakligen tagit plats i Göteborg och Borås. Frågeställningarna har utforskat för- och nackdelarna med upcycling, dessutom har en utvald målgrupp granskats via enkäter för att se deras inställning till ämnet. Resterande information har hämtats från intervjuer samt tidigare forskning. Studien upptäckte vissa svårigheter med att applicera upcycling på sin affärsmodell. Den största utmaningen som belystes var tidsåtgången, problemet kan leda till höga arbetskostnader och ökat konsumentpris. De fördelarna som upcycling bidrar med är att råmaterial och ohälsosamma arbetsförhållanden går att uteslutna. Dessutom kan konsumenten köpa plagg utan att påverka miljön negativt, detta skapar en cirkulär ekonomi. Denna studie görs ur ett hållbarhetsperspektiv och kommer att granska ett nytt möjligt tillvägagångssätt för avfallshantering, vilket gör att den kommer att avgränsa från recycling samt kläduthyrning. Studien kommer inte göra en ekonomisk fördjupning utan endast ta upp grundläggande ekonomiska aspekter. / The textile industry has become one of the most polluting industries in the world. Low prices and fast fashion increasing globally has developed a habit of consuming for leisure and not for needs. The awareness of the textile industry's environmental impact is well spoken about, but now consumers and companies need to take action to make a change. The purpose of this study has been to research the end stages of the textile loop, can textile waste turn into new fashionable clothes? In this thesis the phenomena upcycling will be explained, the advantages it brings to the positive impact on the climate justice. Upcycling means adding value to a garment in its last phase to avoid turning into waste, the business model is used to close the loop. During the phase of this thesis all contact with professionals has been within Swedish borders and the major part of this work has been based in Gothenburg and Borås. The main focus has been to explore the benefits and the difficulties with upcycling. Society’s knowledge and attitude is towards upcycling has been explored with the help of interviews and surveys as well as previous studies. The study discovers the difficulties with applying upcycling to its business model, the main problem is consumption of time, which can cause high labor costs and increase the stock price. The benefits that follows from upcycling is that raw material and bad working conditions can be excluded, it has the ability to close the loop and create a circular economy. This study is made from a perspective of sustainability, but does delimitate from the profoundness of economics. In addition, the study will examine a new way for the end phase of a textile garment and will delimitate the methods of recycling and rental of clothes.

Thesis (M.A. (Mathematics Education)) --University of Limpopo, 2006 / Traditionally, mathematics has been perceived as objective, abstract, absolute and universal subject that is devoid of social and cultural influences. However, the new perspective has led to the perceptions that mathematics is a human endeavour, and therefore it is culture-bound and context-bound. Mathematics is viewed as a human activity and therefore fallible. This research was set out to explore geometrical concepts involved in the traditional circular buildings in Mopani district of Limpopo Province and relate them to the classroom learning in grade 11 classes. The study was conducted in a very remote place and a sample of two traditional circular houses from Xitsonga and Sepedi cultures was chosen for comparison purposes because of their cultural diversity. The questions that guided my exploration were: • Which geometrical concepts are involved in the design of the traditional circular buildings and mural decorations in Mopani district of the Limpopo Province?. How do the geometrical concepts in the traditional circular buildings relate to the learning of circle geometry in grade 11 class?. The data were gathered through my observations and the learners’ observations, my interviews with the builders and with the learners, and the grade 11 learners’ interaction with their parents or builders about the construction and decorations of the traditional circular houses. I used narrative configurations to analyse the collected data. Inductive analysis, discovery and interim analysis in the field were employed during data analysis. From my own analysis and interpretations, I found that there are many geometrical concepts such as circle, diameter, semi-circle, radius, centre of the circle etc. that are involved in the design of the traditional circular buildings. In the construction of these houses, these concepts are involved from the foundation of the building to the roof level. All these geometrical concepts can be used by both educators and learners to enhance the teaching and learning of circle geometry. Further evidence emerged that teaching with meaning and by relating abstract world to the real world makes mathematics more relevant and more useful.

All biological processes are fundamentally inter-molecular interactions. In order to understand, and hence control, biomolecular structure and function, methods are required that probe biological systems at the molecular level, ideally with those molecules being in their native environment. The research summarized herein has at its core the development and application of ultra violet (UV)-visible spectrophotometric techniquies for this prupose, in particular circular dichrosim (CD) and linear dichrosim (LD) but also absorbance, fluorescence and resonance light scattering. The spectroscopy is complemented by fundamental theoretical work on molecular structure and reactivity that forms the basis for designing molecules to bind to biomolecules for a particular structural or functional effect. A brief summary of the contributions of the listed publications to our understanding of 'Molecular aspects of biololecule structure and function' is given below under five headings: Circular dichroism theory Molecular geometry and reactivity Small molecule-macromolecule interactions: spectroscopic probes of inter-molecular geometries Molecular design for nucleic acid structure and control Spectroscopic probes of biomolecule structure: instrumentation and application In general terms these correspond to successive phases of the research programme, however, all areas have been present since the first publications in 1983 and can be traced weaving through all subsequent activity.

This thesis is focussed on structural and functional studies of a novel glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes. GpdQ is highly promiscuous and is the first known phosphatase which is capable of degrading all three classes of phosphate esters (mono-, di- and triesters). Remarkably, GpdQ is also able to hydrolyse stable aliphatic phosphate esters and has been shown to degrade the hydrolysis product of the nerve agent VX. For these reasons, GpdQ has been realised to have potential as a powerful bioremediator for the removal of organophosphate pesticides and nerve agents. GpdQ is a binuclear metallohydrolase in which one of the metal ions is very weakly bound. Chapter 1 introduces the catalytic mechanisms of binuclear metallohydrolases by examining two related phosphate ester-degrading enzymes. Since one of the main features of catalysis addressed in this thesis are the differential metal binding affinities of GpdQ, Chapter 1 also canvasses a range of other binuclear metallohydrolases with similar behaviour. Chapter 2 examines the structural and evolutionary relationship between GpdQ and a number of other related enzymes. Using genome database searches, the two most closely related enzymes are identified. In performing these searches, a novel, putative binuclear metallohydrolase from Homo sapiens is also discovered. This enzyme, Hsa_aTRACP, is most closely related to PAPs, however construction of a homology model indicates that the active site tyrosine residue of PAP is replaced by histidine. In this respect, it may represent an evolutionary link to Ser/Thr protein phosphatases and GpdQ. The biology and chemistry of this putative enzyme is discussed. PAPs are the only binuclear enzymes with an established heterovalent active site of the type Fe(III)-M(II) (where M=Fe, Zn or Mn) whereas the majority of enzymes in this family have homovalent metal centres, including GpdQ and Ser/Thr protein. This is brought about due to the nature of the coordination sphere imposed by the enzyme. The activity of GpdQ can be reconstituted in the presence of Co(II), Zn(II), Mn(II) and Cd(II). Chapter 3 examines the kinetic properties of a binuclear homovalent system by studying the kinetic properties of Cd(II)-substituted GpdQ and a corresponding model complex. This comparative study leads to the identification of a terminal hydroxide molecule as the likely reaction-initiating nucleophile in Cd(II)-GpdQ with a pKa of 9.4. In Chapter 4, a detailed study of the structural, kinetic and spectroscopic behaviour of Co(II)-substituted GpdQ is presented. This chapter specifically probes the formation of the binuclear active site, the role of the metal ions in catalysis, the identity of the nucleophile and the potential role of any first or second coordination sphere residues in the regulation of enzyme activity, proton donation and metal ion coordination. Based on these findings, a detailed reaction mechanism is proposed in which the substrate itself promotes the formation of the catalytically competent binuclear centre and phosphorolysis occurs following nucleophilic attack by a terminal hydroxide molecule. A potential role of Asn80 (a ligand of one of the metal ions) in regulating both substrate and metal binding, and the role of the bridging hydroxide molecule in the activation of the terminal nucleophile is proposed. Chapter 5 employs a combination of kinetic and spectroscopic techniques to probe the proposed catalytic mechanism of GpdQ in depth. The formation of the catalytically competent binuclear centre is observed in pre-steady state studies, an integral first step in the catalytic mechanism. The dissociation and rate constants associated with formation of the binuclear centre are quantified. The rate of substrate turnover in GpdQ is relatively modest but is enhanced by a structural rearrangement involving the flexible Asn80 ligand. This structural change fine-tunes the reaction mechanism, leading to optimal reactivity. The steady-state kinetic properties of a series of metal ion derivatives (Co(II), Cd(II) and Mn(II)) of GpdQ and their reactivity towards a number of substrates are also compared. These findings lead to the conclusion that the reaction mechanism of GpdQ is modulated by both substrate and metal ion. In this respect, GpdQ is adaptive to the environmental conditions to which it is exposed by employing a flexible mechanistic strategy to achieve catalysis. Chapter 6 correlates the electronic and geometric structure of the binuclear centre in GpdQ as a means to probe specific aspects of the mechanism. This study uses the wild type enzyme and a site-directed mutant (Asn80Asp) to examine the structure of the metal ions at two stages of catalysis. The role of the bridging hydroxide molecule in nucleophilic activation is specifically addressed by monitoring changes in the electronic exchange interaction and other structural parameters as a result of phosphate binding. Also, the coordination environment of the metal ions in both the free enzyme and the phosphate-bound enzyme of wild type and Asn80Asp GpdQ were assessed against the currently proposed structures. The findings in this chapter corroborate the proposed catalytic mechanism of GpdQ. In summary, this project led to a detailed understanding of the mechanism of GpdQ, and provided insight into how both the metal ion composition and the identity of the substrate may modulate this mechanism. The knowledge gained may lead to the design of catalytically more efficient derivatives (mutants) of GpdQ for application in bioremediation.

<p>In this Thesis the magnetic and structural properties of thin epitaxial Fe, Co, and Ni films are discussed. Some of the in-situ prepared samples were used to characterize the degree of circular polarization of the newly installed beamline D1011 at MAX-lab. By means of x-ray magnetic circular dichroism (XMCD) and utilizing the associated magneto optic sum rules, the orbital (<i>m</i><i>l</i>) and spin (<i>m</i><i>s</i>) moments are determined directly in <i>m</i><i>B</i>/atom with elemental specificity. The extended x-ray absorption fine structure (EXAFS) measurements yield site specific information on the local crystallographic structure.</p><p>These measurements were performed using the circular x-rays of several beamlines. The influence of the degree of spatial source coherence <i>l</i><i>spat</i> of the x-rays was characterized by means of Fresnel diffractometry. A correlation between enhanced XAS white line intensities and higher values of <i>l</i><i>spat</i> was established for 20 ML Fe, Co, and Ni films on Cu(100).</p><p>The degree of circularly polarized x-rays (<i>P</i><i>c</i>) at beamline D1011 at MAX-lab was characterized by studying Fe films on Cu(100) by means of XMCD. The maximum value of <i>P</i><i>c</i> is experimentally determined to <i>P</i><i>c</i> =0.85.</p><p>The Au/Co/Au trilayer system was studied as a function of Co thickness, temperature, and Au cap thickness. A 10 mono-layer (ML) Co film, with an Au cap of 20 Å, shows a spin reorientation transition (SRT) from an in-plane to an out-of-plane easy direction as the temperature is lowered from 300 K to 200 K. The magnetic properities of these Co films are very different to what is found for bulk samples due to, in particular, the broken symmetry at the interfaces.</p><p>The thickness dependent spin reorientation transition in the Fe/Ag(100) system was characterized by means of XMCD and EXAFS measurements. 3 ML Fe films show an out-of-plane easy direction with an 125% enhanced orbital moment as compared to the 25 ML Fe in-plane film. Simulations of the Fe <i>L</i>-edge EXAFS indicate the bulk Fe bcc structure for film thicknesses of 6-25 ML Fe. For 3 ML Fe strong deviations from this bcc phase is observed.</p><p>Ultrathin Co films deposited on flat and vicinal Cu(111) in the thickness region 1-25 ML were studied by means of XMCD and scanning tunneling microscopy (STM). The vicinal Cu(111) Co deposition leads to the formation of elongated islands preferentially oriented along the step edges. In connection to this particular Co growth mode we observe an increase of both the orbital and the spin moment on the vicinal Cu(111) of about 25% relative to what was observed for Co on flat Cu(111).</p>

In dieser Arbeit wurden die Möglichkeiten und Grenzen für Zirkulardichroismus-Messungen mit Synchrotronstrahlung untersucht. Dazu wurde ein Messaufbau für Zirkulardichroismus-Messungen an zwei Strahlrohren am Berliner Elektronenspeicherring für Synchrotronstrahlung eingesetzt, die für Messungen im Bereich des ultravioletten Lichts geeignet sind. Eigenschaften der Strahlrohre und des Messaufbau wurden in einigen wichtigen Punkten mit kommerziellen Zirkulardichroismus-Spektrometern verglichen. Der Schwerpunkt lag auf der Ausdehnung des zugänglichen Wellenlängenbereichs unterhalb von 180 nm zur Untersuchung des Zirkulardichroismus von Proteinen in diesem Bereich. In diesem Bereich ist es nicht nur die Lichtquelle sondern vor allem die Absorption des Lichts durch Wasser, die den Messbereich bei der Messung biologischer Proben in wässriger Lösung einschränkt. Es wurden Bedingungen gefunden, unter denen der Messbereich auf etwa 160 nm, in einigen Fällen bis auf 130 nm ausgedehnt werden konnte. Dazu musste die Pfadlänge deutlich reduziert werden und verschieden Probenküvetten wurden getestet. Der Einfluss der dabei auftretenden Spannungsdoppelbrechung in den Probenküvetten auf das Messsignal konnte mit einem alternativen Messaufbau deutlich reduziert werden. Systematische Fehler im Messsignal und auftretende Strahlenschäden begrenzen jedoch die Zuverlässigkeit der gemessenen Spektren. Bei Proteinfilmen schränkt die Absorption von Wasser den Messbereich kaum ein. Es wurden jedoch meist deutliche Unterschiede zwischen den Spektren von Proteinfilmen und den Spektren von Proteinen in wässriger Lösung festgestellt. Solange diese Unterschiede nicht minimiert werden können, stellen Proteinfilme keine praktikable Alternative zu Messungen in wässriger Lösung dar. / The possibilities and limitations for synchrotron radiation circular dichroism measurements were investigated in this thesis. Therefore an experimental setup to measure circular dichroism was used at two beamlines at the “Berliner Elektronenspeicherring für Synchrotronstrahlung”(BESSY), which were suitable in the ultraviolet range of light. Properties of the beamlines and the experimental setup were compared to those of commercial circular dichroism spectrometer in some important points. The focus was on the extension of the accessible wavelength range below 180 nm, with the aim to investigate the circular dichroism of proteins in that range. It is not only the light source that limits measurements with aqueous solutions in that range, but mainly the absorption of the light by water. Conditions were found under which the wavelength range was extended to about 160 nm, in some cases even to 130 nm. To achieve this, a significant reduction of the pathlength was necessary. Several sample cells were tested for their usability. The effect of birefringence within the sample cells on the circular dichroism signal could be reduced strongly with an alternative experimental setup. However systematic errors in the circular dichroism signal and appearing radiation damage of the proteins limits the reliability of the measured spectra. By using protein films, the light absorption by water is not a problem anymore. However, significant differences between the circular dichroism spectra of protein films and proteins in aqueous solution occurred in most of the cases. Unless these differences can be eliminated, measuring protein films is not an alternative to measurements in aqueous solution.

The objective of current study was to numerically investigate the flow and heat transfer characteristics in a stationary one pass rectangular channel (AR=4:1) with circular and elliptical pin fin arrays. Two types of elliptical pin fins (a SEF and an N fin whose minor axis length is equal to the diameter of the circular fin) were used. The analysis was performed with an array of six rows of staggered pin fins in the streamwise direction for Reynolds numbers (Re) of 10,000, 20,000, 30,000, 40,000 and 50,000. 3-D, steady simulations were performed using the low Reynolds number k-omega SST turbulence model in the FLUENT CFD code. The data predicted by the current numerical model showed favorable agreement with the experiments in the validation study. It was observed that SEF array produces minimum pressure loss and the highest thermal performance. It was also observed that N fin array produces minimum hot spots and the highest channel averaged Nusselt number ratio values.