Titania and titania-silver nanoparticle deposits made by Liquid Flame Spray and their functionality as photocatalyst for organic- and biofilm removal

Titania and titania-silver nanoparticle deposits were made by Liquid Flame Spray technique, in which the liquid precursor is injected into a high temperature flame, where it will evaporate and nucleate to nanosize particles. One-step and two-step methods were used for preparation of titania-silver deposits. The amount of silver added was 1 wt%. The deposits were collected in the flame zone on steel and glass surfaces and were analyzed by TEM, EDS, XPS and SAXS. The titania deposits consisted of porous nanosized titania agglomerates of primary particles (~10 nm). With silver addition, small spherical silver metal particles (~2 nm) were detected on the agglomerates. An increase in the photocatalytic activity was verified by stearic acid decomposition and biofilm removal using Deinococcus geothermalis as the model organism.     

Second-harmonic generation imaging of metal nano-objects with cylindrical vector beams

We introduce an imaging technique based on second-harmonic generation with cylindrical vector beams that is extremely sensitive to three-dimensional orientation and nanoscale morphology of metal nano-objects. Our experiments and second-harmonic field calculations based on frequency-domain boundary element method are in very good agreement. The technique provides contrast for structural features that cannot be resolved by linear techniques or conventional states of polarization and shows great potential for simple and cost-effective far-field optical imaging in plasmonics.     

I'll Find it Where I Can: Exploring the Role of Resource and Financial Constraints in Search Behaviour among Innovators

The search for new knowledge is often driven by problems that firms face in their innovative activities. Although a considerable effort has been made to explore the search for innovation, little attention has been placed on the concept of problemistic search. Indeed, there are only few studies that examine how the challenges that firms face in their innovation processes shape the nature and direction of their search activities. Using the Finnish Innovation Survey, this study explores the impact of different types of problems on the use of internal and external knowledge sources. The results show that firms under resource constraints tend to use external sources of knowledge in their search activities rather than internal ones. However, those firms who are constrained by finance tend to search both internally and externally. The paper explores the implications of these results for theory and future empirical research.     

System- and circuit-level optimization of PLL designs for DVB-T/H receivers

This article proposes a framework for the optimization of voltage-controlled oscillator (VCO) designs in frequency synthesizers for digital video broadcasting ?C terrestrial/handheld (DVB-T/H) receivers. Linear time-invariant phase-domain model of a charge-pump phase-locked loop (PLL) is devised and includes both flicker (1/f) and thermal noise contributions from the loop oscillators. By modeling the entire receiver, it is shown that there are combinations of flicker and thermal noise contributions that result in a constant sum of inter-carrier interference (ICI) and adjacent channel interference, and constant symbol error rate as well. Consequently, optimization of the VCO phase noise spectrum is defined while maintaining the standard-specified symbol-error rate. Link-level performance evaluation is carried out to validate the stipulated trade-off. The effect of ICI mitigation schemes is discussed. Circuit-level VCO design approaches utilizing the derived trade-off are finally presented. The proposed optimization procedure is generic and is also applicable to other systems based on Orthogonal Frequency-Division Multiplexing.     

Controlling the crystallinity and roughness of atomic layer deposited titanium dioxide films

The surface roughness of thin films is an important parameter related to the sticking behaviour of surfaces in the manufacturing of microelectomechanical systems (MEMS). In this work, TiO2 films made by atomic layer deposition (ALD) with the TiCl4-H2O process were characterized for their growth, roughness and crystallinity as function of deposition temperature (110-300 degrees C), film thickness (up to approximately 100 nm) and substrate (thermal SiO2, RCA-cleaned Si, Al2O3). TiO2 films got rougher with increasing film thickness and to some extent with increasing deposition temperature. The substrate drastically influenced the crystallization behaviour of the film: for films of about 20 nm thickness, on thermal SiO2 and RCA-cleaned Si, anatase TiO2 crystal diameter was about 40 nm, while on Al2O3 surface the diameter was about a micrometer. The roughness could be controlled from 0.2 nm up to several nanometers, which makes the TiO2 films candidates for adhesion engineering in MEMS.     

Total and extractable element concentrations in bed sand material from a medium-sized (32 MW) municipal district heating plant incinerating peat, stumps, sawdust and recycled wood

In Finland, the new limit values of total heavy metal, polychlorinated biphenyl (PCB) and polycyclic aromatic hydrocarbon (PAH), as well as the extractable heavy metal, dissolved organic carbon (DOC), fluoride, sulphate, and chloride concentrations for bed sand material used as an earth construction agent came into force in June 2009. The total heavy metal (i.e. Cd, Cu, Pb, Cr, Zn, As, V, Ba and Mo) concentrations in the studied bed sand material were clearly lower than the current Finnish limit values for the maximum allowable heavy metal concentrations for materials used as an earth construction agent. However, the extractable concentration of Ba (24.6 mg kg⁻¹; d.w.) in the bed sand material exceeded the limit value for covered structures (20 mg kg⁻¹; d.w.). However, in Finland, the competent environmental authority may relax the maximum limit values up to 30% in certain circumstances. Therefore, if, the environmental authority relaxes the maximum limit value for the extractable concentration of Ba by up to 30% to the value of 26 mg kg⁻¹ (d.w.) for covered structures, the extractable concentration of Ba (24.6 mg kg⁻¹; d.w.) in the bed sand material is below this relaxation.     

Effects of Compression and Filler Particle Coating on the Electrical Conductivity of Thermoplastic Elastomer Composites

Elastomeric polymers can be filled with metallic micro- or nanoparticles to obtain electrical conductivity, in which the conductivity is largely determined by the intrinsic conductivity of and contact resistance between the particles. Electrons will flow through the material effectively when the percolation threshold for near-neighbor contacts is exceeded and sufficiently close contacts between the filler particles are realized for electron tunneling to occur. Silver-coated glass microparticles of two types (fibers and spheres) were used as fillers in a thermoplastic elastomer composite based on styrene–ethylene–butylene–styrene copolymer, and the direct-current (DC) resistance and radiofrequency impedance were significantly reduced by coating the filler particles with octadecylmercaptan. Not only was the resistance reduced but also the atypical positive piezoresistivity effect observed in these elastomers was strongly reduced, such that resistivity values below 0.01 Ω cm were obtained for compression ratios up to 20%. In the DC measurements, an additional decrease of resistivity was obtained by inclusion of π-extended aromatic compounds, such as diphenylhexatriene. Some qualitative theories are presented to illuminate the possible mechanisms of action of these surface coatings on the piezoresistivity.     

Displacement control of a mobile crane using a digital hydraulic power management system

The Digital Hydraulic Power Management System (DHPMS) is an innovation that is claimed to significantly improve the energy efficiency of hydraulic systems. It is based on digital pump-motor technology but has multiple independent outlets; hence, the transformer function can be realized as well. A new idea is to connect the outlets of the DHPMS directly into the cylinder chambers without any throttling valves in order to minimize hydraulic losses and to enable energy recovery. This article introduces the first experimental results of using this direct connection approach. Firstly, the system under study is presented and then a method for the displacement control is proposed. Open-loop position tracking responses with different loadings are presented, as is an analysis of the accuracy of steady-state velocity tracking. In addition, energy losses in the system are studied. The results show that the technique is valid. Moreover, the open-loop positioning error is under one percent in the measured trajectories, even though the DHPMS used has only six pistons. However, more pistons will be needed to improve the control of low velocities and to reduce the pressure ripple. On/off valve technology is a challenge, and compact, fast and leak-free valves with high flow capacity are required.     

Strategies for software-based hybrid business models

The open source approach to software development has been used by software organizations in tandem with their existing business models, which are based on proprietary software licensing. This led to the creation of hybrid business models that merge open source and proprietary paradigms. This paper explores the practices used by software product vendors using hybrid business models and proposes strategies emerging out of these practices using interpretive, single case study research design.