Tailored surface properties of semi-fluorinated block copolymers by electrospinning

Diblock copolymers based on polystyrene (PS) macroinitiators and four different fluorinated monomers (perfluorooctyl ethyl methacrylate (FMA), pentafluorostyrene (FS), perfluorooctyl-ethylene oxymethyl styrene (EMS), 2,3,5,6-tetrafluoro-4-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecaoxy)styrene (FSF)) were synthesized via atom transfer radical polymerization (ATRP). The lengths of the PS and fluorinated blocks were altered and the surface and self-assembling properties of the polymers were compared with respect to the fluorinated monomer used and the fluorine content. The surface properties, contact angles and surface tension, were enhanced by the existence of the CF₃ groups at the end of the alkyl chains compared with poly(pentafluorostyrene). Hydrophobicity of the surfaces was further enhanced by electrospinning the polymer solutions, which yielded superhydrophobic surfaces with water contact angles >150° for polymers having CF₃ groups.     

Atomic layer deposition and characterization of biocompatible hydroxyapatite thin films

Atomic layer deposition (ALD) was used to produce hydroxyapatite from Ca(thd)₂ (thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) and (CH₃O)₃PO onto Si(100) and Corning (0211). Film crystallinity, stoichiometry, possible impurities and surface morphology were determined. The as-deposited films contained significant amounts of carbonate impurities however, annealing at moist N₂ flow reduced the carbonate content even at 400 °C. The as-deposited Ca-P-O films were amorphous but rapid thermal annealing promoted the formation of the hydroxyapatite phase. Mouse MC 3T3-E1 cells were used for the cell culture experiments. According to the bioactivity studies cell proliferation was enhanced on as-deposited ALD-grown Ca-P-O films and greatly enhanced on films annealed at 500 °C in comparison with reference cells on borosilicate glass or cell culture polystyrene.     

How attentional systems process conflicting cues. The superiority of social over symbolic orienting revisited.

We investigated orienting of attention by social and symbolic cues presented inside/outside the locus of attention. Participants responded to laterally presented targets preceded by simultaneously presented gaze and arrow cues. Participants’ attention was allocated to either of the cues and the other cue served as a distractor. In Experiments 1–4 nonpredictive cues were employed. The validity of the attended cue and distractor were varied orthogonally. Valid cues and distractors produced additive facilitation to reaction times when compared to invalid cues and distractors. The effects of gaze and arrow distractors were similar. When the cue was 100% valid and the distractor 50% valid (Experiment 5), distractor validity had no effect on reaction times. When realistic gaze and arrow cues were employed (Experiment 6), arrow but not gaze distractors influenced the reaction times. The results suggest that social and symbolic directional information can be integrated for attention orienting. The processing of social and symbolic directional information can be modulated by top-down control, but the efficiency of the control depends on the visual saliency of the cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Space-time constant modulus algorithm for multipath removal on the reference signal exploited by passive bistatic radar

The authors address the problem of multipath cancellation in the reference signal used in passive bistatic radar (PBR), which exploits an existing transmitter as emitter of opportunity. The presence of multipath echoes in the reference signal is demonstrated to strongly affect the detection performance of passive radar. Based on the well-known constant modulus algorithm (CMA) approach in the time-domain, new multi-dimensional techniques are considered for the adaptive equalisation of the reference signal based on an array of antennas and multiple receiving channels. The effectiveness of these techniques for PBR purposes is demonstrated with reference to typical simulated scenarios. The considered strategies, addressed as space-CMA and space-time-CMA, are shown to be able to recover the performance loss because of the multipath contribution in the reference signal so that they appear as very appealing solutions for PBR equipped with an array of antennas and multiple receiving channels.     

Emotional scenes in peripheral vision: Selective orienting and gist processing, but not content identification.

Emotional-neutral pairs of visual scenes were presented peripherally (with their inner edges 5.2° away from fixation) as primes for 150 to 900 ms, followed by a centrally presented recognition probe scene, which was either identical in specific content to one of the primes or related in general content and affective valence. Results indicated that (a) if no foveal fixations on the primes were allowed, the false alarm rate for emotional probes was increased; (b) hit rate and sensitivity (A') were higher for emotional than for neutral probes only when a fixation was possible on only one prime; and (c) emotional scenes were more likely to attract the first fixation than neutral scenes. It is concluded that the specific content of emotional or neutral scenes is not processed in peripheral vision. Nevertheless, a coarse impression of emotional scenes may be extracted, which then leads to selective attentional orienting or--in the absence of overt attention--causes false alarms for related probes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Low level gas multicounter for 14C dating of small samples

A compact gas multicounter has been constructed and is undergoing tests. Up to 14 methane samples can be counted simultaneously in an array of 10 ml (at NTP) copper counters at a pressure of 1–8 bar. The gas filling, application of high voltage and decay energy monitoring are microprocessor controlled. Multichannel analyses (256 ch. sample and cosmic detector energy data), sample identity, counting time and critical validity parameters are stored on disc. Numerical discrimination and manipulations of counting parameters can be performed without destroying the original data set. Statistical quality control is based on chi-square and Poisson distribution of countrates around their mean in user defined energy regions as well as “ time of arrival” (TA) of pulses mode. TA analysis offers the user an early means of recognition of some types of system malfunction that otherwise might remain undetected for long periods of time. Pulse shape analysis is used to discriminate sample beta from environmental radiation pulses resulting in a low background with compact and relatively inexpensive shielding.     

Geometric solution strategy of Laplace problems with free boundary

This paper introduces a geometric solution strategy for Laplace problems. Our main interest and emphasis is on efficient solution of the inverse problem with a boundary with Cauchy condition and with a free boundary. This type of problem is known to be sensitive to small errors. We start from the standard Laplace problem and establish the geometric solution strategy on the idea of deforming equipotential layers continuously along the field lines from one layer to another. This results in exploiting ordinary differential equations to solve any boundary value problem that belongs to the class of Laplace's problem. Interpretation in terms of a geometric flow will provide us with stability considerations. The approach is demonstrated with several examples. Copyright © 2015 John Wiley & Sons, Ltd.     

Breath figure templated semifluorinated block copolymers with tunable surface properties and binding capabilities

Patterning of functionalized polymeric surfaces enables the adjustment of their characteristics and use in novel applications. We prepared breath figure (BF) films from three semifluorinated diblock copolymers, which all are composed of a polystyrene block and a semifluorinated one to compare their surface properties. “Click” chemistry was employed to one of the polymers, containing a poly(pentafluorostyrene) block to incorporate hydrophilic sugar or carboxylic acid moieties. The structure of the polymer alters the obtained porous morphology of the films. Contact angle (CA) analyses of the BF films reveals that the surface porosity increases water CAs compared with solvent cast films, and, in the case of hydrophobic polymers, leads to significant increase in the CAs of dodecane. The hydrophobicity of the BF films is further amplified by the removal of the topmost layer which leads in some cases to superhydrophobic surfaces. BF films containing glucose units are hydrophilic exhibiting water CAs below 90°. These glycosylated porous surfaces are shown to bind lectin Con A‐FITC or can be labelled with isothiocyanate marker. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41225.     

Collaborative knowledge management—A construction case study

Due to the new threats and challenges faced by the construction industry today, construction companies must seek new solutions in order to remain ahead of the competition. Knowledge has been identified to be a significant organisational resource, which if used effectively can provide competitive advantage. A lot of emphasis is being put on how to identify, capture and share knowledge in today's organisations. It has been argued over the years that due to the fragmented nature of the construction industry and ad-hoc nature of the construction projects, capture and reuse of valuable knowledge gathered during a construction project pose a challenge. As a result critical mistakes are repeated on projects and construction professionals have to keep “reinventing the wheel”. Given the nature of construction projects, collaborative knowledge management seems to be the most appropriate solution to capture project based knowledge. Information and communication technologies offer a number of solutions to implement collaborative knowledge management solutions. This paper discusses a range of these solutions and presents a case study where a collaborative knowledge management solution is implemented across a multi functional construction company.The work presented in the case study was carried out while the first author was employed by the case study organisation. A social web application was implemented to solve a particular knowledge sharing problem within the organisation's concrete pumping business. The new solution provided an effective and simple way to create knowledge by taking employees' ideas through an iterative cycle of discussion.