Mechanically inspired laser scribing of thin brittle materials

Laser processing of thin flexible ceramics and glasses is challenging due to the incurred brittleness and unfavorable thermal and optical properties of such materials. We describe an alternative laser cutting method which utilizes surface stress raisers to cleave brittle substrates along a defined path. An ultrashort laser source is used to precisely pattern a plurality of aligned elliptical recesses on the material surface. The apex of an ellipse concentrates applied tensile stresses. Depending on the elliptical dimensions, the achievable stress concentration factor can be up to 50. The orientation of the ellipses defines a preferred scribing path. The technique was successfully applied to thin flexible yttria stabilized zirconia ceramic and borosilicate glass substrates. The form and properties of the material play an important role during the fracture process. Polycrystalline ceramics were found to accurately auto cleave along the path due to stresses produced during the laser ablation. The resulting fractured surface is of higher quality and strength than surfaces cut using full body laser cutting techniques, while the crystalline phase is preserved. The optical setup is simple, low cost, and compatible with roll‐to‐roll manufacturing.     

Support for tenure mix by residents local to the Carlton Housing Estate,Melbourne, Australia

In this paper, we report on the level of support for tenure mix policies of residents living proximate to the Carlton Housing Estate mixed tenure redevelopment in Melbourne Australia. In a telephone survey of 200 residents living in the area surrounding the estate, the majority of respondents were supportive of tenure mix. Those who were financially comfortable or only spoke English were significantly more supportive than those reporting more difficult financial circumstances or who spoke a language other than English. The reasons for support for tenure mix included avoiding ghettoization, building community and social role modelling. The reasons for opposing tenure mix reflected a concern for the loss of public housing, a view that public and private tenants would not want to be co-located and that public tenants weren’t as deserving as others of living in a good inner city location. There were also concerns from both groups about how tenure mix might work in practice. Policy implications are discussed.     

A Management Concept for Driving Sustainability in Marginalised Communities in South Africa

Cities are the frontline for addressing issues of global sustainability. This notion has been inducted into the development discourse of the Global North with varying degrees of success. However, urban environments in the Global South face unique challenges, and Western-derived perceptions of sustainability are inappropriate for these regions. This paper examines issues of sustainability within impoverished urban communities in South Africa. Survey interviews helped inform and examination of South Africa’s urban morphology to determine the specific obstacles to sustainable urban development of marginalised communities in South Africa. In response, the study proposes the application of the principles founded in facilities management (FM) at a macro/urban scale. Urban facilities management (UFM) is a new alignment of FM that advocates a holistic view of an urban precinct to facilitate systemic solutions with a variety of urban role-players. A conceptual framework for a UFM aligned development process for marginalised communities of the Global South is developed based on issues identified through the interviews. This framework seeks to enable a comprehensive integration of social, environmental, economic, and institutional dimensions of sustainability into an urban development model. In doing so, it holds the promise of unlocking the opportunities for developing/emerging countries to pioneer global sustainability.     

The inhibitory effects of silver nanoparticles, silver ions, and silver chloride colloids on microbial growth

Emerging nanomaterials are of great concern to wastewater treatment utilities and the environment. The inhibitory effects of silver nanoparticles (Ag NPs) and other important Ag species on microbial growth were evaluated using extant respirometry and an automatic microtiter fluorescence assay. Using autotrophic nitrifying organisms from a well-controlled continuously operated bioreactor, Ag NPs (average size=14+/-6 nm), Ag(+) ions (AgNO(3)), and AgCl colloids (average size=0.25 microm), all at 1mg/L Ag, inhibited respiration by 86+/-3%, 42+/-7%, and 46+/-4%, respectively. Based on a prolonged microtiter assay, at about 0.5mg/L Ag, the inhibitions on the growth of Escherichia coli PHL628-gfp by Ag NPs, Ag(+) ions, and AgCl colloids were 55+/-8%, 100%, and 66+/-6%, respectively. Cell membrane integrity was not compromised under the treatment of test Ag species by using a LIVE/DEAD Baclight bacterial viability assay. However, electron micrographs demonstrated that Ag NPs attached to the microbial cells, probably causing cell wall pitting. The results suggest that nitrifying bacteria are especially susceptible to inhibition by Ag NPs, and the accumulation of Ag NPs could have detrimental effects on the microorganisms in wastewater treatment.     

Stereotype threat and hazard perception among provisional license drivers

Stereotype threat refers to the negative impact a stereotype about one's group can have on one's performance in domains relevant to the stereotype. In the current paper, we explore whether the negative stereotype of provisional license drivers (PLDs) might produce stereotype threat in a driving-related hazard perception task. We manipulate threat by asking participants to self-identify as PLDs in a categorization condition, or by reminding PLD participants explicitly of the stereotype of PLDs in an explicit stereotype condition. Results reveal increments in hazard perception in the categorization condition, and decrements in hazard perception in the explicit stereotype condition. Mediation analysis reveals that hazard perception performance is fully mediated by increased effort in the categorization condition and by decreased effort in the explicit stereotype condition. We discuss these findings in terms of their implications for stereotype threat and its mediators, and for public policy that explicitly discriminates between PLDs and other driver groups.     

Master Planned Estates and Collective Private Assets in Australia: Research into the Attitudes of Planners and Developers

Master planned estates have grown in number Australia and internationally as a favoured form of development in new and infill estates. This paper explores the use of legal entities known in the state of Victoria as owners' corporations to hold communal assets in private ownership for the exclusive use of those living in master planned estates. The privatization of assets that would normally be held by municipal government has been associated by some with heightened conflict in estates, greater costs for residents and increased separation from the larger community. This paper seeks to investigate the motivations and attitudes of both local government planners and developers in utilizing forms of private collective ownership in residential estates in a major city of Australia, Melbourne. This empirical investigation demonstrates that developers generally utilize these ownership structures in order to provide a different, but not necessarily better, standard of facilities as a means of market differentiation. Planners, on the other hand, are more diffident in their endorsement of privatized community ownership and demonstrate a degree of concern about their changed relationship to residents in such estates. The research suggests that issues relating to this choice of ownership of community assets have not been fully considered by local government, particularly in terms of protecting the long-term interests of residents.     

3D microstructure construction and quantitative evaluation of sintered ZrO2 under different sintering conditions

In this study, the microstructural evolution of yttria-stabilized ZrO₂ after different sintering conditions is quantitatively presented. Focused ion beam (FIB) is used as a critical tool for sintering microstructural evolution understanding. 3D images are constructed with Amira software based on a series of 2D images obtained from FIB cutting of samples with an interval of 10 nm. Pore connectivity, pore numbers, grain-pore interfacial areas, and pore tortuosity of the sintered samples are calculated by IDL software using the 3D images. Our new tortuosity definition describes the actual sample microstructural changes while the other two in the literature fail to do so. FIB cutting and 3D microstructure reconstruction offer many new aspects of sintering microstructure that have not been available before.     

Hollow superparamagnetic iron oxide nanoshells as a hydrophobic anticancer drug carrier: intracelluar pH-dependent drug release and enhanced cytotoxicity

With curcumin and doxorubicin (DOX) base as model drugs, intracellular delivery of hydrophobic anticancer drugs by hollow structured superparamagnetic iron oxide (SPIO) nanoshells (hydrodynamic diameter: 191.9 ± 2.6 nm) was studied in glioblastoma U-87 MG cells. SPIO nanoshell-based encapsulation provided a stable aqueous dispersion of the curcumin. After the SPIO nanoshells were internalized by U-87 MG cells, they localized at the acidic compartments of endosomes and lysosomes. In endosome/lysosome-mimicking buffers with a pH of 4.5-5.5, pH-dependent drug release was observed from curcumin or DOX loaded SPIO nanoshells (curcumin/SPIO or DOX/SPIO). Compared with the free drug, the intracellular curcumin content delivered via curcumin/SPIO was 30 fold higher. Increased intracellular drug content for DOX base delivered via DOX/SPIO was also confirmed, along with a fast intracellular DOX release that was attributed to its protonation in the acidic environment. DOX/SPIO enhanced caspase-3 activity by twofold compared with free DOX base. The concentration that induced 50% cytotoxic effect (CC(50)) was 0.05 ± 0.03 μg ml(-1) for DOX/SPIO, while it was 0.13 ± 0.02 μg ml(-1) for free DOX base. These results suggested SPIO nanoshells might be a promising intracellular carrier for hydrophobic anticancer drugs.