Influence of Ageing on the Corrosion Resistance of the ZnAl22Cu3 and ZnAl40Cu3 Alloys

Subject of examinations were ZnAl22Cu3 and ZnAl40Cu3 alloys. The samples after solutionizing 3850C/10h and ageing 1750C/10h and for comparative purposes, in the initial state (just after casting) have been studied. Corrosion tests were carried out in “acid rain” solution. The scope of the examinations included potentiodynamic and potentiostatic tests , examination of the surface and structure of the samples after corrosion. The research found that corrosion of ZnAl22Cu3 and ZnAl40Cu3 alloys in the "acid rain" environment leads to a depletion of zinc in the upper surface layer and its enrichment in aluminium and copper resulting in decreasing the corrosion rate. Depending on the parameters (temperature, time) solutioning and ageing of ZnAl22Cu3 and ZnAl40Cu3 alloys can lead to an increase or decrease of the corrosion resistance in the "acid rain" environment.

Research on the Stability Evaluation of Waterproofing Capacity of Asphalt Compound Waterproofing Layer of Underground Parking Area Upper Slab after Fire Damage

This research intends to evaluate the level of affect of fire damage on the waterproofing layers performance level that are applied to the upper surface layer of underground parking area slab. Samples were collected directly from the fire damage site in order to evaluate how much of the waterproofing performance is retained in the water proofing layer. As per the designed procedure of this research, the involved structures that underwent fire damage were first examined and the samples that were afflicted by the fire damage were visually inspected. The sample collected from the fire damage site was taken and compared with the same undamaged sample type in order to evaluate the difference of the former's waterproofing performance capacity. The conclusion of the research finds that despite the 250mm width concrete surface slab being subjected to intense fire damage, there was no deterioration in the waterproofing layer's performance capacity.

Build-up and decline of organic matter during PeECE III

Increasing atmospheric carbon dioxide (CO2) concentrations due to anthropogenic fossil fuel combustion are currently changing the ocean's chemistry. Increasing oceanic [CO2] and consequently decreasing seawater pH have the potential to significantly impact marine life. Here we describe and analyze the build-up and decline of a natural phytoplankton bloom initiated during the 2005 mesocosm Pelagic Ecosystem CO2 Enrichment study (PeECE III). The draw-down of inorganic nutrients in the upper surface layer of the mesocosms was reflected by a concomitant increase of organic matter until day t11, the peak of the bloom. From then on, biomass standing stocks steadily decreased as more and more particulate organic matter was lost into the deeper layer of the mesocosms. We show that organic carbon export to the deeper layer was significantly enhanced at elevated CO2. This phenomenon might have impacted organic matter remineralization leading to decreased oxygen concentrations in the deeper layer of the high CO2 mesocosms as indicated by deep water ammonium concentrations. This would have important implications for our understanding of pelagic ecosystem functioning and future carbon cycling.

Interaction of surface acoustic waves and ultraviolet light in ZnO films

The frequency response of a 37 MHz bulk LiNbO3 surface acoustic wave (SAW) filter with a 200-nm-thick ZnO overlayer exhibited a downshift in the frequency with ultraviolet (UV) light due to acoustoelectric interactions between the photo-generated carriers in the semiconducting ZnO and the surface acoustic waves. In contrast, a 36 MHz ZnO thin film SAW delay-line with insulating ZnO films exhibited an upshift in the frequency. The response was more pronounced at higher harmonics (130–315 MHz) and was attributed to changes in the elastic/dielectric properties in the upper surface layer of ZnO. A linear change in the frequency with UV intensity shows immense applicability for wireless ultraviolet sensor applications.

Growth mechanism of vapor-deposited diamond

An elementary-reaction mechanism of diamond growth by a vapor deposition process is proposed. The central postulate is that the main monomer growth species is acetylene. The mechanism basically consists of two alternating steps: surface activation by H abstraction of a hydrogen atom from a surface carbon and the addition of one or two acetylene molecules. During the addition reaction cycle a number of solid C–C bonds is formed and hydrogen atoms migrate from a lower to an upper surface layer. The mechanism is in general agreement with the macroscopic views of the Russian researchers and is consistent with the numerous experimental observations reported in the literature.

The transient behaviour of the electric field strength above an atmospheric surface duct

The duct model used here is that of Kahan and Eckart. It has a discontinuous drop of the otherwise constant relative permittivity at the upper duct boundary. The earth is assumed to be a perfect conductor and an ideal plane. The source of the electromagnetic field is taken to be a vertical magnetic dipole, in the upper surface layer, with an arbitrary time-varying moment. The method used for solution is essentially based on the application of two functional transforms. Starting with the wave equation of the electric field strength and applying a Laplace transform in time, one then finds a two-dimensional Fourier transform in the horizontal coordinates in space leading to an integral representation of the solution of the wave equation in transform space, considering initial, boundary, and transition conditions. Having chosen a horizontal polarization of the primary source, one can determine the transient behaviour of the electric field strength at any distance above the duct.