Assessing the Antimicrobial Activity of Polyisoprene Based Surfaces

There has been an intense research effort in the last decades in the field of biofouling prevention as it concerns many aspects of everyday life and causes problems to devices, the environment, and human health. Many different antifouling and antimicrobial materials have been developed to struggle against bacteria and other micro- and macro-organism attachment to different surfaces. However the “miracle solution” has still to be found. The research presented here concerns the synthesis of bio-based polymeric materials and the biological tests that showed their antifouling and, at the same time, antibacterial activity. The raw material used for the coating synthesis was natural rubber. The polyisoprene chains were fragmented to obtain oligomers, which had reactive chemical groups at their chain ends, therefore they could be modified to insert polymerizable and biocidal groups. Films were obtained by radical photopolymerization of the natural rubber derived oligomers and their structure was altered, in order to understand the mechanism of attachment inhibition and to increase the efficiency of the anti-biofouling action. The adhesion of three species of pathogenic bacteria and six strains of marine bacteria was studied. The coatings were able to inhibit bacterial attachment by contact, as it was verified that no detectable leaching of toxic molecules occurred.     

External stimulus‐responsive interfaces in polymer nanocomposites

Materials that can switch from stiff to soft or from brittle to tough by slightly changing the temperature, pH, electric, or magnetic fields of their environments, can have a pronounced impact on many applications, including sensors, biomedical materials for less invasive surgeries, and packaging materials. In this work, temperature‐sensitive poly(N‐isopropyl acrylamide) grafts and low molar mass polyethylene glycol were incorporated in the interfacial region between clay nanoparticles and a bacteria‐derived polyhydroxybutyrate matrix to determine if the application of an external stimulus, such as small changes in temperature, could increase the toughness of the nanocomposites. The obtained materials were characterized by using thermal analysis, infrared spectroscopy, dynamic light scattering and dynamic mechanical tests. Mechanical properties were also evaluated at different temperatures and showed that small changes in temperature, such as from 25°C to 40°C, led to a pronounced increase in strain at break of the nanocomposites containing the modified interface. The external stimulus associated with the increase in temperature from 25°C to 40°C can reduce the interfacial interactions between clay and polymer matrix and create a highly plasticized polymer layer between the components of the nanocomposite, which favored the sliding of the interface and ultimately led to high values of elongation. POLYM. COMPOS., 37:1342–1349, 2016. © 2014 Society of Plastics Engineers     

Death and Memory: Clothing Bequests in English Wills 1650–1830

Specific clothing bequests form a distinct and often intimate feature in a range of English wills during the seventeenth and eighteenth centuries. Carefully and symbolically allocated to new owners, garments were thus imbued with commemoration as well as financial worth. This paper suggests that gender differentials in this practice have been exaggerated as individual men could be as committed to the process as their female counterparts. Crucially, men and women without children or partners were most disposed to draw up detailed wills reallocating a range of possessions, especially clothing. In this creation of stewardship for chosen garments, individual personality and familial situation were more decisive than any general social or economic considerations.     

Efficient disparity vector prediction schemes with modified P frame for 2D camera arrays

An efficient disparity estimation algorithm for multi-view video sequences, recorded by a two-dimensional camera array in which the cameras are spaced equidistantly, is presented. Because of the strong geometrical relationship among views, the disparity vectors of a certain view can for most blocks be derived from the disparity vectors of other views. A frame constructed using that idea is called a D frame in this work. Three new prediction schemes which contain D frames are proposed for encoding 5 × 3 multi-view video sequences. The schemes are applied to several multi-view image sequences taken from a camera-array and they are compared in terms of quality, bit-rate and complexity. The experimental results show that the proposed prediction schemes significantly decrease the complexity of the encoder at a very low cost of quality and/or bit-rate.     

Disassembly sequencing: A survey

This paper is a survey of the presently available literature on disassembly sequencing, including the papers that are closely related to this topic. Disassembly theory is applied to complex products such as mechanical, electromechanical and electronic appliances. It is required for end-of-life processing and for maintenance and repair. Apart from these applications, disassembly is studied for supporting the analysis of assembly processes. Disassembly sequencing involves the search for all possible disassembly sequences and the selection of the optimum solution out of these. In each application, a slightly different approach can be observed, including level of detail, degrees of freedom, and the role of uncertainty. Disassembly sequencing also plays a major role in the modern design process and is an invaluable tool in concurrent engineering. Its connection with the more detailed or component level and the less detailed level or process level including logistics, is highlighted. This presentation of the state of the art is intended as a stimulus for further research in this interesting field.     

Calibrating the Water-Hammer Response of a Field Pipe Network by Using a Mechanical Damping Model

Hydraulic transient field tests have been conducted in a water distribution network. Existing transient models are applied to model the measured responses, but poor matches are obtained apart from the estimation of the initial rise of pressure. Possible reasons for these discrepancies include the effects of demands, entrained air, unsteady friction, friction losses associated with small lateral pipes, and mechanical damping caused by the interaction of pipes and joints with surrounding soils (including the effects of vibration and different degrees of restraint). These effects are systematically investigated by inclusion of the previously mentioned phenomena in conceptual transient models and calibration to the measured field responses. A mechanical damping-based conceptual transient model is shown to be the only model that can be accurately calibrated to the measured field responses.     

Comparison of Different Oxidation Methods for Recalcitrance Removal of Landfill Leachate

In this work several oxidation methods, such as conventional ozonation, O₃/UV, O₃/UV/ferrous iron and Fenton oxidation, for the removal of recalcitrant organic matter present in landfill leachates are evaluated. The samples of the leachate are taken after a biological treatment and membrane ultra-filtration (UF). The contribution of the UV radiation and the effect of ferrous iron ions on the ozone process efficiency is discussed. At lower ozone dosages, the partial oxidation efficiency is reduced as compared to conventional ozonation and therefore, a higher degree of mineralization of the organic matter is achieved. Finally, the best results are obtained by the Fenton oxidation, however, based on economic considerations this method is not recommended.     

Experimental Study on the Use of Positive Pressure Ventilation for Fire Service Interventions in Buildings with Staircases

During fire service interventions, positive pressure ventilation (PPV) systems with mobile fans are often used to try and make (or keep) a staircase smoke free and to remove smoke from the fire rooms. The positioning (distance from the door opening) and inclination angle of the fan determine the effect of the PPV fans in the staircase. In the present paper results are discussed of an experimental study, performed at full-scale. Based on different sets of cold experiments, the impact is quantified of: the distance between the fan and the door; the inclination angle of a single fan; and the use of multiple fans. The closer the single fan is put to the door opening, the more effective the PPV becomes. Obviously, there is a trade-off with effectiveness of the fire service intervention, since the fan must not block the door opening. With respect to inclination, it is best to apply an inclination angle of 75° (i.e., an upward tilting of the fan axis by 15°, which is the maximum value tested) for ventilation at ground level with the fan tested. This ensures safety in the case of fire at ground level due to full coverage of the entry door opening, while only a relatively limited loss in PPV effectiveness is observed compared to a horizontal fan (in some cases, the PPV effectiveness is even higher with inclined fan). When the fire room is at a higher floor, an inclination angle of 90° (i.e. horizontal fan axis) can generate a higher average flow velocity, depending on the staircase configuration inside the building. If two fans are used, V-shape positioning is shown to be more effective than a set-up in series or in parallel. A V-shape with inner angle of 60° between the fan axes is more effective than an angle of 90°. If three fans are available, still higher average flow velocities are measured. Positioning two fans outside in V-shape and one fan inside at the bottom of the staircase is more effective than putting the three fans outside, On the other hand, the latter set-up may be required for firefighting tactics.