39 research outputs found
Measurements of heat treatment effects on bovine cortical bones by Nanoindentation and compression testing
No full textAuthor name used in this publication: Lau, Kin-Tak.Version of RecordPublishedC
ALMA and Herschel observations of the prototype dusty and polluted white dwarf G29-38
No full textJF gratefully acknowledges the support of the STFC via an Ernest Rutherford Fellowship. AB acknowledges the support of the ANR-2010 BLAN-0505-01 (EXOZODI). MCW and OP are grateful for the support of the European Union through ERC grant number 279973.ALMA Cycle 0 and Herschel PACS observations are reported for the prototype, nearest, and brightest example of a dusty and polluted white dwarf, G29-38. These long-wavelength programmes attempted to detect an outlying, parent population of bodies at 1–100 au, from which originates the disrupted planetesimal debris that is observed within 0.01 au and which exhibits LIR/L* = 0.039. No associated emission sources were detected in any of the data down to LIR/L* ∼ 10−4, generally ruling out cold dust masses greater than 1024–1025 g for reasonable grain sizes and properties in orbital regions corresponding to evolved versions of both asteroid and Kuiper belt analogues. Overall, these null detections are consistent with models of long-term collisional evolution in planetesimal discs, and the source regions for the disrupted parent bodies at stars like G29-38 may only be salient in exceptional circumstances, such as a recent instability. A larger sample of polluted white dwarfs, targeted with the full ALMA array, has the potential to unambiguously identify the parent source(s) of their planetary debris.Peer reviewe
Insight on how biopolymers recovered from aerobic granular wastewater sludge can reduce the flammability of synthetic polymers
No full textEco-friendly flame retardants are greatly required to meet the expectations of low-toxicity, environmental compatibility and sustainability. Extracellular polymeric substances (EPS), the biopolymers recovered from excess granular wastewater sludge, have been successfully incorporated into poly(vinyl alcohol) (PVA) by a solution casting method. Self-extinguishment of EPS was observed in a vertical burn test. Positive effects of EPS on the reduction of heat release rate and CO emission of EPS/PVA composites were also demonstrated. The presence of various types of phosphates was detected in the EPS and a possible flame-retardant mechanism has been proposed. The investigation of using granular sludge EPS to reduce the flammability of synthetic polymers may open the possibility of converting wastewater sludge into bio phosphorus-based flame retardants.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Environmental Biotechnolog
Signs of a faint disc population at polluted white dwarfs
No full textObservations of atmospheric metals and dust discs around white dwarfs provide important clues to the fate of terrestrial planetary systems around intermediate-mass stars. We present Spitzer Infrared Array Camera observations of 15 metal polluted white dwarfs to investigate the occurrence and physical properties of circumstellar dust created by the disruption of planetary bodies. We find subtle infrared excess emission consistent with warm dust around KUV 15519+1730 and HS 2132+0941, and weaker excess around the DZ white dwarf G245-58, which, if real, makes it the coolest white dwarf known to exhibit a 3.6 μm excess and the first DZ star with a bright disc. All together our data corroborate a picture where (1) discs at metal-enriched white dwarfs are commonplace and most escape detection in the infrared (possibly as narrow rings), (2) the discs are long lived, having lifetimes on the order of 106 yr or longer and (3) the frequency of bright, infrared detectable discs decreases with age, on a time-scale of roughly 500 Myr, suggesting large planetesimal disruptions decline on this same time-scale
Rotational Moulding Cycle Time Reduction through Exterior Mould Modification
No full textFull text is available to authenticated members of The University of Auckland only.Rotational moulding has been heralded as a plastic moulding method with great
potential. The process offers virtually stress-free products having no weld lines or
material wastage, and utilises relatively inexpensive moulds. Yet, its widespread
growth is hindered due to long production cycle times, which are limited by the time
required to heat up and cool down a mould and the product within. To address this
issue, efforts have been made by the author to enhance heat transfer to and from
moulds, ultimately reducing cycle times.
The aims of this project are four-fold:
. To investigate the effect of convective heat transfer to and from a mould by
changing the external mould surface (i.e. adding roughness elements or pins to
the mould surface).
• To predict cycle time reductions gained through the use of surface enhanced
moulds.
• To validate the predicted cycle times with experimental trials.
. To recommend a combination of moulding conditions, applied together with
surface enhanced moulds, for the rotomoulding industry to pursue.
Due to the complex rotation of the mould, heating and cooling are most commonly
achieved by convection to the external surfaces of the mould using air as the transfer
medium. Two methods of heat transfer enhancement were considered, which are
applicable to both external forced convection and mould exterior surface
modification within the existing rotomoulding process. These methods are rough
and extended surfaces.
A series of preliminary analytical studies (predictions) and experiments were
performed using roughness-enhanced and pin-enhanced plates to verify that these
methods work. The results for the average effective heat transfer coefficient, h^,
from the parametric studies for the extended surfaces were too high compared with
the preliminary experimental data. While a turbulent flow was expected in the
rotomoulding machine, the reality was a transitional flow (i.e. a mixture of laminar
and turbulent flows). As a result, the correlations used in the parametric studies for
the rough surfaces were invalid. Better prediction methods, which involved both
analytical and numerical studies, were employed to improve the prediction of heJfec
for both rough and extended surfaces.
The h values were then applied directly into an existing rotomoulding simulation
package, RotoSim, to predict cycle times. Based on the preliminary experimental
results and predicted heat transfer coefficients, dimensions and array of roughness
elements and pins were decided. Three cubical aluminium moulds (i.e. plain,
roughness-enhanced, and pin-enhanced) were fabricated for the experimental
purposes. To validate cycle time predictions, a series of experimental trials were
carried out.
Experimental and predicted results have shown significant cycle time reductions for
both surface enhanced moulds. The average experimental cycle time reductions
gained through the use of surface enhanced moulds were 18 and 28% for the
roughness-enhanced and pin-enhanced moulds respectively. Even though the
prediction methods fail to estimate the exact experimental cycle times, they are very
useful for predicting relative cycle time reductions between the plain and surface
enhanced moulds. The average predicted cycle time reductions were 21 and 32% for
the roughness-enhanced and pin-enhanced moulds respectively. These results
indicate that the predicted and experimental cycle time reductions are in excellent
agreement with each other.
This study has demonstrated that a significant reduction in rotomoulding cycle times
can be achieved through the use of surface enhanced moulds. This thesis also provides a foundation for performance analysis of surface enhanced moulds.
Recommendations have been made to maximise the benefits from such moulds,
without depreciating the quality of the end products. Applying the proposed
moulding conditions (i.e. a combination of higher oven flow rates, internal mould
pressure, and water-cooling), the cycle time reductions were approximately 65 and
70% for roughness-enhanced and pin-enhanced moulds respectively (weighted
against the plain mould with 'normal· moulding conditions). Such savings are very
significant, inviting the rotomoulding community to incorporate these techniques
efficiently in an industrial setting
Proceedings Transborder Library Forum 2007 : bridging the digital divide : crossing all borders = Memorias Foro Transfronterizo de Bibliotecas 2007 : cerrando la brecha digital : cruzando todas las fronteras
No full textIt is with great pleasure that we present this edition of the Proceedings of the Transborder Library Forum (Foro). The 2007 Transborder Library Forum was held at Arizona State University in Tempe, Arizona in February, 2007. We are pleased that there will be both a print edition and an online edition. Editing has been kept to a minimum to preserve the intent of the author in the language the paper was presented. The theme for the 2007 Foro was Bridging the Digital Divide. Topics ranged from international copyright issues to getting information to students in widely dispersed communities with little or no infrastructure except the Internet. While most attendees and speakers were from the USA and Mexico, we also had some from Uganda, Kenya, Hungary, and the West Indies
Assessing Heat-Treatment Effects on Bovine Cortical Bones by Nanoindentation
No full textAmong different sterilization methods, heat-treatment of bone is recognized as one of the simple and practical methods to lower the human immunodeficiency virus (HIV) infection and overcome the risks of rejection and disease transfer from allograft and xenograft during bone transplantation. In order to best characterize the micro-structural mechanical property of bone after heat treatment, the nanoindentation technique was applied in this study to measure the localized elastic modulus and hardness for interstitial lamellae and osteons lamellae of bovine cortical bones at temperature 23°C (room temperature-pristine specimen), 37°C, 90°C, 120°C and 160°C, respectively. The elastic modulus (E) and hardness (H) of interstitial lamellae obtained higher values as compared with osteons lamellae which show that interstitial lamellae are more stiff and mineralized than osteons. Moreover, as a specimen pre-heat treated at 90°C, the E and H values of interstitial lamellae and osteons were closed to a pristine specimen. For a specimen pre-heat treated at 120°C, both interstitial lamellae and osteons obtained an increase in E and H values. As a specimen pre-heat treated at 160°C, the interstitial lamellae and osteons obtained a slight decrease in E and H values. These findings are correlated to results reported by other researchers [1, 2] that calcified collagen molecules starts to degenerate at about 120°C and complete at 160°C. Interestingly, when a specimen was pre-heat treated at 37°C, both interstitial lamellae and osteons obtained significant decreases in E values of 57% and 40%, respectively as compared to the pristine specimen; while in H values, there was a decrease of 27.4% and 15%, respectively. Thus, this paper will investigate the mechanical properties of bovine cortical bones under various temperature ranges by nanoindentation technique.</jats:p
Enhancement of fire resistance and mechanical performance of polypropylene composites containing cellulose fibres and extracellular biopolymers from wastewater sludge
No full textIn the present research, a bio-based flame retardant (FR) was prepared using a biopolymer derived from wastewater sludge to improve the fire performance of polypropylene (PP). Extracellular polymeric substances (EPS), which were extracted from wastewater aerobic granular sludge, were absorbed into cellulose-based fibres, such as flax and toilet papers. Thermogravimetric analysis results indicated that the EPS-cellulose fibres played a significant role in enhancing the char formation of PP composite. Furthermore, the incorporation of the bio-based FR into PP restricted its vertical burning characteristics, and at the same time enhanced the tensile moduli of the composites. The reaction between phosphoric acids from EPS and hydroxyl groups of cellulose fibres improved dehydration and char formation of the composites to enhance the overall fire reaction properties. This study opens up new possibilities for the wastewater-derived biopolymer “EPS” to prepare the bio-inspired FRs for cellulose-based fibres and composites, and enhance sustainability of wastewater sludge treatment
FREN 399 Capstone Presentations - 2020
No full textAbstract in French and English (Ashley R. Dalbec):
L’identité informe les langues et ains l’enseignement des langues doit refléter cette réalité. Le monde devient de plus en plus mondialisé et le discours de l’éducation doit changer de façon à refléter un monde plus connecté mais plus divers que celui d’auparavant. Pourtant, pour la France, un pays qui a une histoire de monolinguisme, l’inclusion de la diversité dans les approches d’enseignement s’avère un peu compliquée. À travers une vue sociolinguistique, l’auteur explorera l’histoire de l’Éducation nationale en France et de l’enseignement des élèves allophones nouvellement arrivés (EANA), pour comprendre les approches de nos jours. Cet essai exposera ce qui fonctionne bien dans l’accueil des EANA et ce qui améliore l’expérience et l’intégration scolaire des nouveaux arrivés en France. Cet essai répondra aux questions suivantes : Est-ce que le système perpétue le monolinguisme et comment est-ce que ce système pourrait contribuer à la création d’une méthode de pédagogie et de didactique plurilinguistique ? Comment est-ce que l’enseignement du français comme langue étrangère ou seconde peut honorer les identités et cultures plurilingues des EANA au lieu de forcer une perte implicite de langue primaire qui n’est pas le français ?
Identity informs language, and as a result, the teaching of languages must also reflect this truth. The world is becoming more and more globalized and the discourse of teaching must change to reflect a more connected but diverse world. However, for France, a country with a history of monolingualism, the resolution to this lack of diversity in teaching approaches proves to be a bit more complicated. The author will explore the history of Éducation Nationale in France and the teaching of newly arrived allophone students, known as EANA, through a sociolinguistic lens, to better understand current day approaches. This paper will explore what works well to help the EANA and what teaching approaches improve their experiences and integration into the French school system. This essay will respond to the following questions: How does the education system perpetuate monolingualism and how could this system contribute to the creation of a multilingual and multicultural approach? How can the teaching of French as a second language or foreign language honor the multicultural identities and cultures of its newly arrived allophone students instead of forcing them to lose their forcing the learning of French?
Abstract in French and English (Jacob A. Debes):
Nous remarquons une tension en France entre les banlieues et les villes. Cette tension est exemplifiée dans le 93e département. Le neuf-trois, comme c’est connu par les Français, est situé à quelques kilomètres au nord de Paris. La tension en France est exacerbée par trois aspects primordiaux : les convictions postcoloniales, le traitement des minorités et la violence policière. Dans ce travail nous allons explorer d’où vient cette tension et la base de réalité qui la définit. De plus, nous allons regarder d’une façon plus proche les aspects qui exacerbent la tension. Quelle est la réponse gouvernementale en France ? Est-ce que cette réponse est bien reçue par le public français, spécifiquement par le mouvement pour l’égalité en France ? Nous examinerons le potentiel pour un changement positif en France et qui est en train de commencer ce changement.
In France we see a tension between the suburbs and the cities. This tension is exemplified in 93rd department. The neuf-trois, as the French commonly know it, is located a few kilometers north of Paris. This tension is exacerbated by three aspects: Post-colonial convictions, treatment of minorities, and police violence. In this analysis we will explore where this tension comes from and the reality it is based on. In addition, we will examine more closely the aspects that exacerbate that tension. Therefore, what is the governmental response in France? Is this response being well received by the French public, specifically by the new movement for equality? Is there a potential for positive change in France and who is trying to begin this change
