Narrow emission linewidths of positioned InAs quantum dots grown on pre-patterned GaAs(100) substrates

We report photoluminescence measurements on a single layer of site-controlled InAs quantum dots (QDs) grown by molecular beam epitaxy (MBE) on pre-patterned GaAs(100) substrates with a 15 nm re-growth buffer separating the dots from the re-growth interface. A process for cleaning the re-growth interface allows us to measure single dot emission linewidths of 80 μeV under non-resonant optical excitation, similar to that observed for self-assembled QDs. The dots reveal excitonic transitions confirmed by power dependence and fine structure splitting measurements. The emission wavelengths are stable, which indicates the absence of a fluctuating charge background in the sample and confirms the cleanliness of the re-growth interface.     

TEM observation of liquid-phase bonded aluminum–silicon/aluminum nitride hetero interface

Liquid-phase bonded aluminum–silicon/aluminum nitride interface structure was investigated using high-resolution transmission electron microscopy. A textured layer of aluminum formed a stable orientation relationship with aluminum nitride, which showed Al(111) to be tilted by about 4° with respect to the AlN(0001) interface plane. The unique orientation relationship between Al and AlN was predicted as one of the stable orientation relationships using coincidence of reciprocal lattice point method, which surveys the degree of geometrical coherency between two crystals in three-dimensional space. A stable orientation relationship was found to be (001)[1_boxclose \bar{1} 0]Al//(2[`2] \bar{2} 03)[11[`2] \bar{2} 0]AlN.     

The employment of 0/90 unsymmetric samples for the characterisation of the thermo-oxidation behaviour of composite materials at high temperatures

The present paper explores the possibility to employ 0/90 unsymmetric plates as a tool for characterising the thermo-oxidation behaviour and the environmental ageing of composite materials at high temperature. The continuous monitoring of the out of plane displacements and the curvatures of such samples can be used for the identification of the thermo-oxidation induced irreversible chemical strain/stress build up and material property changes. A model has been developed to take into account the effects of thermo-oxidation on the time-dependent plate curvatures. Simulations show that 0/90 unsymmetric plates are very sensitive to thermo-oxidation induced changes, thus effective for capturing the searched thermo-oxidation effects. The predictions of the present model may serve for parametric studies and design of tests.     

Impact of local versus global ligand density on cellular adhesion

α(v)β(3) integrin-mediated cell adhesion is crucially influenced by how far ligands are spaced apart. To evaluate the impact of local ligand density versus global ligand density of a given surface, we used synthetic micronanostructured cell environments with user-defined ligand spacing and patterns to investigate cellular adhesion. The development of stable focal adhesions, their number, and size as well as the cellular adhesion strength proved to be influenced by local more than global ligand density.     

Curcumin associated magnetite nanoparticles inhibit in vitro melanoma cell growth

Curcumin is a natural product possessing therapeutic properties but the low water solubility of this compound limits its use. We have successfully incorporated curcumin into a bilayer of dodecanoic acid attached to magnetite nanoparticles in an effort to maximize solubility and delivery efficiency. Curcumin/magnetite nanoparticles were characterized using diffused reflectance infra-red fourier transform spectroscopy (DRIFTS) and X-ray powder diffraction (XRD). Moreover curcumin associated magnetite nanoparticles inhibited in vitro melanoma cell growth. An inhibitory concentration (IC50) of 66.0 +/- 3.0 microM (48 +/- 2.2 microg-iron/mL) was observed for the curcumin/magnetite nanoparticles. Fluorescent microscopy revealed that curcumin associated magnetite nanoparticles were internalized by the melanoma cells and remained in the cytoplasm. The curcumin/magnetic nanoparticles synthesized in this study possess magnetic and water solubility properties making this a novel curcumin formulation with therapeutic potential.     

Montmorillonite functionalized with pralidoxime as a material for chemical protection against organophosphorous compounds

Montmorillonite K-10 functionalized with α-nucleophilic 2-pralidoxime (PAM) and its zwitterionic oximate form (PAMNa) is introduced as a versatile material for chemical protection against organophosphorous (OP) compounds such as pesticides and chemical warfare agents (CWA). Upon inclusion into the montmorillonite interlayer structure, the pyridinium group of PAMNa is strongly physisorbed onto acidic sites of the clay, leading to shrinking of the interplanar distance. Degradation of diethyl parathion by PAMNa-functionalized montmorillonite in aqueous-acetonitrile solutions occurred primarily via hydrolytic conversion of parathion into diethylthio phosphoric acid, with the initial stages of hydrolysis observed to be pseudo-first-order reactions. Hydrolysis catalyzed by the clay intercalated by PAMNa was 10- and 17-fold more rapid than corresponding spontaneous processes measured at 25 and 70 °C, respectively. Hydrolytic degradation of diisopropyl fluorophosphate (DFP), a CWA simulant, was studied on montmorillonite clay functionalized by PAMNa and equilibrated with water vapor at 100% relative humidity by 31P high-resolution magic angle spinning NMR and was observed to be rather facile compared with the untreated montmorillonite, which did not show any DFP hydrolysis within 24 h. The incorporation of the functionalized clay particles into elastomeric film of polyisobutylene was shown to be a means to impart DFP-degrading capability to the film, with clay particle content exceeding 18 wt %.     

Quantitative photochemical immobilization of biomolecules on planar and corrugated substrates: a versatile strategy for creating functional biointerfaces

Methods for the generation of substratespresenting biomolecules in a spatially controlled manner are enabling tools for applications in biosensor systems, microarray technologies, fundamental biological studies and biointerface science. We have implemented a method to create biomolecular patterns by using light to control the direct covalent immobilization of biomolecules onto benzophenone-modified glass substrates. We have generated substrates presenting up to three different biomolecules patterned in sequence, and demonstrate biomolecular photopatterning on corrugated substrates. The chemistry of the underlying monolayer was optimized to incorporate poly(ethylene glycol) to enable adhesive cell adhesion onto patterned extracellular matrix proteins. Substrates were characterized with contact angle goniometry, AFM, and immunofluorescence microscopy. Importantly, radioimmunoassays were performed to quantify the site density of immobilized biomolecules on photopatterned substrates. Retained function of photopatterned proteins was demonstrated both by native ligand recognition and cell adhesion to photopatterned substrates, revealing that substrates generated with this method are suitable for probing specific cell receptor-ligand interactions. This molecularly general photochemical patterning method is an enabling tool for the creation of substrates presenting both biochemical and topographical variation, which is an important feature of many native biointerfaces.     

Striving to achieve it all: men and work-family-life balance in Sweden and the UK

Although there is a vast literature on issues of work-life balance, most of the research is grounded on the traditional view of work-life balance as a female-oriented entitlement. So far little attention has been paid to how men balance their work-life situations, especially the ‘new men’ who are keen to share the family care. We contribute to filling this gap by critically examining how male academics in construction-related departments at universities in Sweden and the UK construct their relationships with family and work. Narrative analysis was applied on in-depth interviews with seven academics from each country, who were at different phases in their careers. Three core narratives emerged from the data: family connected with partner; work as key priority; and desire to pursue personal projects, all of which competed for the narrators’ sparse time. The narrative that by far received most space and most storylines in all the interviews was ‘work as priority’, implying that in spite of gender equality policies and campaigns, work-life balance remains a female-oriented concern. Both Swedish and British men in our sample found juggling family and life most challenging. This work-family-life triad left many feeling that they had no time to do a good job in any sphere and in Sweden in particular combination pressure was intense. Curiously, despite these tensions and increasing demands for many of our respondents work remains a positive construct, possibly because of the strong conceptual identification of ‘self’ as an academic.     

Social identity in construction: enactments and outcomes

A social identity lens and theories of self-reinforcement are used to explore identity work and processes of identification at the micro-level in a large construction company. Rich data from a qualitative case study show that a strong collective identification is self-defining for the vast majority of managers in the organization, regardless of their role and function. This collective identification revolved around the trade of ‘being a construction worker’, associated with the traits of being practically oriented and of having a long professional background in construction. This collective identification seems to reinforce itself by a combination of pulling and pushing movements and/or ‘being blind’ vis-à-vis those that stand outside its self-defining core, content, and behaviours. The results of the study suggest that self-defining at the individual and group levels has implications for organizational performance and outcomes. It is also suggested that the use of a social identity lens can help increase understanding of interpersonal relations, collaboration, and change initiatives in the construction industry.