Thesis (Ph. D.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 382-398).

Diss. Linköping : Linköpings universitet, 2009.

Thesis (M.S.W.)--University of Hong Kong, 1978.

published_or_final_version / Social Work / Master / Master of Social Work

The aim of this study was to explore some social workers’ and psychologists’ perspectives ontheir collaboration concerning unaccompanied refugee children. More specifically; in which situations do the social workers and psychologists collaborate with each other in their work with unaccompanied refugee children and what challenges and possibilities do they describe in their collaborative work? This qualitative study was carried out in one municipality in Sweden with a high quantity of unaccompanied refugee children. Three social workers and two psychologists were interviewed. The interviewees described existing collaboration between the two professions when working with unaccompanied refugee children as regarding the young person ́s health. Most often the collaboration was described as taking place in so called sip-meetings that is an obligatory meeting between the two professions regarding the young person's health. However, also challenges regarding their collaboration as lack of resources and communication between these two professions emerged and are discussed.

Thesis (M. Soc. Sc.)--University of Hong Kong, 1982.

published_or_final_version / Architecture / Master / Master of Architecture

Thesis (M.Soc.Sc.)--University of Hong Kong, 1982. / Also available in print.

Abstract Transition metal dichalcogenide (TMD) materials crystalize in a layered structure with a stoichiometry MX₂ where M is a transition metal (Mo, W, Tc, Re, V, Nb, Ta, Ti, Zr, Hf) and X is a chalcogen (S, Se, Te). While there is a strong covalent bond between the chalcogen and the metal atoms in each 2-dimensional (2D) sheet, the bulk 3-dimensional crystals are held together by weak van der Waals forces acting on the adjacent 2D sheets allowing for micromechanical and liquid phase exfoliation into nanostructures composed of either a single layer or a few layers. Since the electronic band structure depends not only on the chemistry but also on the number of layers, a whole new range of metal, semimetal and semiconductor materials may be achieved. These properties, among many other advantages (e.g. tunable band structure, high mobility of carriers, easy intercalation with ions), make TMDs appealing and timely for applications in solar cells and photodetectors, heterogeneous catalysis, electrocatalytic electrodes, energy storage and in (electro) chemical sensing. Motivated by the anticipated fascinating properties of TMDs, this research work focuses on the synthesis, characterization and application of a novel hybrid WS₂ nanomaterial. While the original goal of the research work was to develop a simple method to synthesize WS₂ nanowires, it became clear that instead of nanowires a hybrid nanowire-nanoflake (NW-NF) structure could be synthesized by a simple thermal sulfurization of hydrothermally grown WO₃ nanowires. The structure, morphology and composition of the new materials were analyzed by X-ray diffraction, Raman spectroscopy, electron microscopy and X-ray photoelectron spectroscopy. Temperature dependent electrical measurements carried out on random networks of the nanostructures showed nonlinear characteristics and a negative temperature coefficient of resistance indicating that the hybrids were semiconducting. Resistive gas sensors were prepared and exposed to H₂S, CO, NH₃, H₂ and NO and to which the devices displayed ultra-high sensitivity (0.043 ppm⁻¹) towards H₂S with a detection limit of 20 ppb. The results suggest further exploration of gas sensing with TMDs as potential competitive alternatives to the classical metal oxide based devices. Moreover, photodetector devices with excellent visible light response were also demonstrated using an individual WS₂ NW-NF hybrid as well as its random networks having photoresponsivity of up to 400 mAW⁻¹. This was two orders of magnitude higher than that measured for other 2D materials based devices. Overall, the WS₂ nanowire-nanoflake hybrid is a truly multipurpose and multifunctional semiconductor making it a promising material for advanced micro, nano and optoelectronics devices. / Tiivistelmä Siirtymämetallidikalkogenidistä (transition metal dichalcogenide, TMD) olevat materiaalit kiteytyvät kerroksittaisiksi rakenteiksi, joiden stoikiometria on MX₂, missä M on siirtymämetalli (Mo, W, Tc, Re, V, Nb, Ta, Ti, Zr, Hf) ja X on kalkogeeni (S, Se, Te). 2-ulotteisessa (2D) tasossa kalkogeenin ja metallin välillä on voimakas kovalenttinen sidos, mutta suuremmassa kolmiulotteisessa kiteessä viereisiä tasoja sitoo toisiinsa vain heikot van der Waals-voimat, jolloin tasot on mahdollista erottaa mikromekaanisesti ja nestefaasikuorinnalla yksittäisiksi tai muutamasta kerroksesta koostuvaksi nanorakenteeksi. Koska elektronivyörakenne ei riipu ainoastaan kemiallisesta koostumuksesta vaan myös kerrosten lukumäärästä, voidaan muodostaa täysin uusia metallisia, puolimetallisia tai puolijohdemateriaaleja. Nämä ominaisuudet monien muiden lisäksi (esim. räätälöity vyörakenne, korkeanliikkuvuuden varauksen kuljettajat, helppo ionien interkelaatio) tekevät TMD-materiaaleista kiinnostavia ja ajankohtaisia aurinkokennoihin, valokennoihin, heterogeeniseen katalyysiin, sähkökatalyyttisiin elektrodeihin, energiavarastoihin ja sähkökemiallisiin antureihin. TDM-materiaalien oletettavasti kiehtovien ominaisuuksien motivoimana tämä tutkimus keskittyy uusien hybridi-WS₂-nanomateriaalien synteesiin, karakterisoimiseen ja sovellutuksiin. Tutkimuksen alkuperäinen tavoite oli kehittää yksinkertainen menetelmä WS₂-nanolankojen syntetisoimiseksi, mutta kävi ilmi että nanolankojen sijaan syntyi nanolanka-nanohiutale -hybridirakenne (nanowire-nanoflake, NW-NF), kun hydrotermisesti kasvatettuja WO₃-nanolankoja rikitettiin termisesti. Näiden uusien materiaalien rakenne, morfologia ja koostumus on analysoitu röntgendiffraktiolla, Raman-spekstrokopialla, elektronimikroskoopilla ja röntgenfotoelektronispektroskopialla. Valikoimattomista nanorakenteista koostuvien verkostojen lämpötilasta riippuvien sähköisten ominaisuuksien mittaukset osoittavat epälineaarisia piirteitä ja negatiivinen resistanssin lämpötilakerroin viittaa hybridien puolijohtavuuteen. Materiaalista valmistettiin resistiivisiä kaasuantureita, jotka altistettiin H₂S:lle, CO:lle, NH₃:lle, H₂:lle ja NO:lle, näistä anturi osoitti erittäin suurta herkkyyttä H₂S:lle (0.043 ppm) havaintorajan ollessa 20 ppb. Tulokset kannustavat TMD-materiaalien kaasuanturisovellutusten jatkotutkimukseen tarjoten potentiaalisesti kilpailukykyisen vaihtoehdon perinteisille metallioksidi-pohjaisille laitteille. Lisäksi, yksittäisillä WS₂-nanolanka-nanohiutalepartikkeleilla sekä valikoimattomilla nanolanka-nanohiutalehybridiverkostoilla demonstroitiin valokenno, jonka vaste näkyvään valoon oli jopa 400 mAW⁻¹ ollen kaksi kertaluokkaa korkeampi kuin muilla 2D-materiaaleihin perustuvilla kennoilla. Kaiken kaikkiaan, WS₂-nanolanka-nanohiutalehybridi on todella monikäyttöinen ja monipuolinen puolijohde ollen lupaava materiaali kehittyneille mikro-, nano- ja optoelektronisille laitteille.

Globalization impacts the Architecture, Engineering and Construction (AEC) industry; customers in the AEC industry are seeking lower costs, faster construction schedules and higher quality services. In order to keep up with the changing demand and to stay competitive in the global AEC industry, firms are forming joint ventures and outsourcing design and services work.  As a result, these new trends in the AEC industry require the collaboration of widely dispersed and diverse project workers and companies.  Accordingly, it becomes increasingly important to understand the impact of diversity on performance.  In this sense, the initial aim of this study was to find empirical evidence on how differences in national culture and language may affect performance in Global Project Networks (GPNs).  According to the results of the first experiment comparing the performance of multi-cultural versus mono-cultural simulated project networks over time, I found cultural and linguistic diversity to have a negative impact on initial performance. However, culturally and linguistically diverse project networks studied achieved better adaptation performance that has long term advantages. Even though GPNs have long term performance benefits, bringing the widely dispersed project participants together is costly.  Therefore, firms are seeking ways to employ collaboration technologies to bring together the project participants.  Little research exists to examine how to increase the efficiency of GPNs that collaborate using technologies such as virtual workspaces to perform design work.  In order to examine collaboration in GPNs utilizing virtual workspaces, I conducted two experiments.  In the first study, I investigated the formation and the maintenance of Transactive Memory Systems (TMSs) and cohesive subgroups as a proxy for performance in two facilitated and two non-facilitated global virtual project networks.  I found a negative impact on collaboration effectiveness when process facilitators engaged in content facilitation in virtual project networks, which restricts the establishment of TMSs. The findings of the first study revealed inappropriate ways of facilitating GPNs collaborating in virtual workspaces, which motivated the second study.  In the second experiment, I observed two global and two domestic virtual project networks that were appropriately facilitated.  I examined the interactions between network members in order to identify whether significant differences between the collaboration approaches of global and domestic virtual project networks exist. Facilitators were utilized more frequently in global networks, particularly in the early stages of collaboration. Boundary spanning visualization technologies within the virtual workspace were also utilized more frequently by the global network members; however, this was due more to the spatial richness of the task than the maturity of the collaboration. The overall findings have significant implications in improving the effectiveness of global project network collaborations in virtual workspaces. / Ph. D.