Rapid Macrocell Tests of Enduramet® 32 Stainless Steel Bars

The corrosion resistance of EnduraMet® 32 stainless steel bars was evaluated using the rapid macrocell test outlined in Annexes A1 and A2 of ASTM A955-10. Based on the test results, the EnduraMet® 32 stainless steel bars satisfy the requirements of ASTM A955-10

Rapid Macrocell Tests of LDX 2101® Stainless Steel Bars

The corrosion resistance of LDX 2101® duplex stainless steel bars is evaluated using the rapid macrocell test specified in Annex A2 of ASTM A955-09b and compared to the performance of 2205 pickled stainless steel (2205p). LDX 2101® bars were tested in the asreceived condition as well as after submersion in simulated concrete pore solution with a pH of 13.4 for two weeks prior to testing. The LDX 2101® stainless steel bars meet the requirements of ASTM A955-09b, exhibiting limited staining and slight corrosion on the bars in salt solution with a maximum individual corrosion rate of 0.44 μm/yr and a maximum average corrosion rate of 0.10 μm/yr. No significant difference was observed in the behavior between bars tested in the as-received condition and bars tested after submersion in simulated concrete pore solution. The 2205p bars exhibited no visible corrosion products on the bars in salt solution and no measureable corrosion. Both the LDX 2101® and 2205p stainless steel bars exhibited moderate staining of the bars used as cathodes in oxygenated pore solution

Rapid Macrocell Tests of Enduramet® 2304 Stainless Steel Bars

The corrosion performance of epoxy-coated steel meeting the requirements of ASTM A775 with the coating in an undamaged condition and two damaged conditions (0.04% and 0.83% damaged area) is evaluated in accordance with Annexes A1 and A2 of ASTM 955 and compared with the corrosion performance of conventional reinforcing steel meeting the requirements of ASTM A615 steel and low-carbon, chromium steel meeting the requirements of A1035, with the latter in both the as-received and pickled conditions. Epoxy-coated bars provide significantly better corrosion performance than conventional reinforcing steel. The macrocell corrosion rates for bars with a damaged area equal to 0.04% of the area exposed to the solutions in the test are relatively low, and are, on average, similar to those observed for the undamaged epoxy-coated bars. Both undamaged and 0.04% damaged area epoxy-coated specimens meet the requirements for stainless steels specified in Annexes A1 and A2 of ASTM 955, with an average corrosion rate not exceeding 0.25 μm/yr and the corrosion rate of no individual specimen exceeding 0.50 μm/yr. The macrocell corrosion rates for bars with a damaged area equal to 0.83% of the area exposed to the solutions in the test average 1 to 1.5 μm/yr based on total bar area under the severe exposure conditions provided. Conventional and A1035 steel exhibit average values near 30 μm/yr for and 20 μm/yr, respectively. Pickling provides initial protection to A1035 steel bars, and to some bars for the duration of the test, but once corrosion initiates, corrosion appears to be similar to that observed on non-pickled bars

Rapid Macrocell Tests of Enduramet® 33, Enduramet® 316LN, and Endurament® 2205 Stainless Steel Bars

The corrosion resistance of EnduraMet® 33, EnduraMet® 316LN, and EnduraMet® 2205 stainless steel reinforcing bars is evaluated using the rapid macrocell test outlined in Annexes A1 and A2 of ASTM A955-10. Based on the test results, all three types of stainless steel satisfy the requirements of ASTM A955-10

Rapid Macrocell Tests of ASTM A775, A615, and A1035 Reinforcing Bars

The corrosion performance of epoxy-coated steel meeting the requirements of ASTM A775 with the coating in an undamaged condition and two damaged conditions (0.04% and 0.83% damaged area) is evaluated in accordance with Annexes A1 and A2 of ASTM 955 and compared with the corrosion performance of conventional reinforcing steel meeting the requirements of ASTM A615 steel and low-carbon, chromium steel meeting the requirements of A1035, with the latter in both the as-received and pickled conditions. Epoxy-coated bars provide significantly better corrosion performance than conventional reinforcing steel. The macrocell corrosion rates for bars with a damaged area equal to 0.04% of the area exposed to the solutions in the test are relatively low, and are, on average, similar to those observed for the undamaged epoxy-coated bars. Both undamaged and 0.04% damaged area epoxy-coated specimens meet the requirements for stainless steels specified in Annexes A1 and A2 of ASTM 955, with an average corrosion rate not exceeding 0.25 μm/yr and the corrosion rate of no individual specimen exceeding 0.50 μm/yr. The macrocell corrosion rates for bars with a damaged area equal to 0.83% of the area exposed to the solutions in the test average 1 to 1.5 μm/yr based on total bar area under the severe exposure conditions provided. Conventional and A1035 steel exhibit average values near 30 μm/yr for and 20 μm/yr, respectively. Pickling provides initial protection to A1035 steel bars, and to some bars for the duration of the test, but once corrosion initiates, corrosion appears to be similar to that observed on non-pickled bars

Dynamics of light propagation in spatiotemporal dielectric structures

Propagation, transmission and reflection properties of linearly polarized plane waves and arbitrarily short electromagnetic pulses in one-dimensional dispersionless dielectric media possessing an arbitrary space-time dependence of the refractive index are studied by using a two-component, highly symmetric version of Maxwell's equations. The use of any slow varying amplitude approximation is avoided. Transfer matrices of sharp nonstationary interfaces are calculated explicitly, together with the amplitudes of all secondary waves produced in the scattering. Time-varying multilayer structures and spatiotemporal lenses in various configurations are investigated analytically and numerically in a unified approach. Several new effects are reported, such as pulse compression, broadening and spectral manipulation of pulses by a spatiotemporal lens, and the closure of the forbidden frequency gaps with the subsequent opening of wavenumber bandgaps in a generalized Bragg reflector

Auger Recombination in Semiconductor Quantum Wells

The principal mechanisms of Auger recombination of nonequilibrium carriers in semiconductor heterostructures with quantum wells are investigated. It is shown for the first time that there exist three fundamentally different Auger recombination mechanisms of (i) thresholdless, (ii) quasi-threshold, and (iii) threshold types. The rate of the thresholdless Auger process depends on temperature only slightly. The rate of the quasi-threshold Auger process depends on temperature exponentially. However, its threshold energy essentially varies with quantum well width and is close to zero for narrow quantum wells. It is shown that the thresholdless and the quasi-threshold Auger processes dominate in narrow quantum wells, while the threshold and the quasi-threshold processes prevail in wide quantum wells. The limiting case of a three-dimensional (3D)Auger process is reached for infinitely wide quantum wells. The critical quantum well width is found at which the quasi-threshold and threshold Auger processes merge into a single 3D Auger process. Also studied is phonon-assisted Auger recombination in quantum wells. It is shown that for narrow quantum wells the act of phonon emission becomes resonant, which in turn increases substantially the coefficient of phonon-assisted Auger recombination. Conditions are found under which the direct Auger process dominates over the phonon-assisted Auger recombination at various temperatures and quantum well widths.Comment: 38 pages, 7 figure

Citizen participation in news

The process of producing news has changed significantly due to the advent of the Web, which has enabled the increasing involvement of citizens in news production. This trend has been given many names, including participatory journalism, produsage, and crowd-sourced journalism, but these terms are ambiguous and have been applied inconsistently, making comparison of news systems difficult. In particular, it is problematic to distinguish the levels of citizen involvement, and therefore the extent to which news production has genuinely been opened up. In this paper we perform an analysis of 32 online news systems, comparing them in terms of how much power they give to citizens at each stage of the news production process. Our analysis reveals a diverse landscape of news systems and shows that they defy simplistic categorisation, but it also provides the means to compare different approaches in a systematic and meaningful way. We combine this with four case studies of individual stories to explore the ways that news stories can move and evolve across this landscape. Our conclusions are that online news systems are complex and interdependent, and that most do not involve citizens to the extent that the terms used to describe them imply

'You can take a horse to water but you can't make it drink': Exploring children's engagement and resistance in family therapy

The final publication is available at Springer via http://dx.doi.org/10.1007/s10591-012-9220-8Children’s engagement and disengagement, adherence and non-adherence, compliance and non-compliance in healthcare have important implications for services. In family therapy mere attendance to the appointments is no guarantee of engaging in the treatment process and as children are not the main initiators of attendance engaging them through the process can be a complex activity for professionals. Through a conversation analysis of naturally occurring family therapy sessions we explore the main discursive strategies that children employ in this context to passively and actively disengage from the therapeutic process and investigate how the therapists manage and attend to this. We note that children competently remove themselves from therapy through passive resistance, active disengagement, and by expressing their autonomy. Analysis reveals that siblings of the constructed ‘problem’ child are given greater liberty in involvement. We conclude by demonstrating how therapists manage the delicate endeavour of including all family members in the process and how engagement and re-engagement are essential for meeting goals and discuss broader implications for healthcare and other settings where children may disengage