Electrical Properties of Lead Zirconate Titanate Thin Films With a ZrO2 Buffer Layer on an Electroless Ni-Coated Cu Foil

The effect of zirconia (ZrO₂) buffer layers on the phase development and electrical properties of lead zirconate titanate (PZT, 52/48) capacitors on an electroless Ni (P)-coated Cu foil was investigated. It was demonstrated that the buffer layer can be used to engineer the final properties. The incorporation of the ZrO₂ buffer layers retained acceptable capacitance densities (>350 nF/cm² for 50 nm thick ZrO₂), while significantly reducing leakage currents and improving reliability (<10⁻⁷ A/cm² after 1 h at 25 VDC for 100 nm thick ZrO₂), compared with PZT thin films directly on electroless Ni (P). The results are particularly important for embedded capacitor applications.     

Contaminant particles removal by negative air ionic cleaner in industrial minienvironment for IC manufacturing processes

This study was carried out in a closed test chamber under natural decay, negative ionic air cleaner application, as well as air mixing mechanism with negative ionic air cleaner. Among three operation modes, the air mixing mechanism with negative ionic air cleaner can reduce particles better under the flow field condition. In the air mixing, especially vigorous one (5 ACH (Air Changes per hour)), enhanced the air cleaning effect. The highest removal efficiency was measured at a height of 0.6 m from the floor and it was decreased substantially with an increase in height. The relative effectiveness of negative ionic air cleaners was predicted to decrease with an increasing particle size. We also found that there was a limited horizontal diffusion of ions. The empirical curves fit based for the concentration gradient of NAI (Negative air ionization) generated was developed for estimating the NAI concentration with different heights and distances from the source of negative ionic air cleaner discharge.     

The influence of travelling fires on a concrete frame

When building fires occur in large, open compartments they rarely burn uniformly across an entire floor plate of a structure. Instead, they tend to travel, igniting fuel in their path and burning it out as they move to the next fuel package. Current structural fire design methods do not account for these types of fires. This paper applies a novel methodology for defining a family of possible heating regimes to a framed concrete structure using the concept of travelling fires. A finite-element model of a generic concrete structure is used to study the impact of the family of fires; both relative to one another and in comparison to the conventional codified temperature-time curves. It is found that travelling fires have a significant impact on the performance of the structure and that the current design approaches cannot be assumed to be conservative. Further, it is found that a travelling fire of approximately 25% of the floor plate in size is the most severe in terms of structural response. It is concluded that the new approach is simple to implement, provides more realistic fire scenarios, and is more conservative than current design methods.     

Mechanisms controlling lateral and vertical porewater migration of depleted uranium (DU) at two UK weapons testing sites

Uranium associations with colloidal and truly dissolved soil porewater components from two Ministry of Defence Firing Ranges in the UK were investigated. Porewater samples from 2-cm depth intervals for three soil cores from each of the Dundrennan and Eskmeals ranges were fractionated using centrifugal ultrafiltration (UF) and gel electrophoresis (GE). Soil porewaters from a transect running downslope from the Dundrennan firing area towards a stream (Dunrod Burn) were examined similarly. Uranium concentrations and isotopic composition were determined using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Multi-Collector-Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS), respectively.The soils at Dundrennan were Fe- and Al-rich clay-loam soils whilst at Eskmeals, they were Fe- and Al-poor sandy soils; both, however, had similar organic matter contents due to the presence of a near-surface peaty layer at Eskmeals. These compositional features influenced the porewater composition and indeed the associations of U (and DU). In general, at Dundrennan, U was split between large (100 kDa-0.2 μm) and small (3-30 kDa) organic colloids whilst at Eskmeals, U was mainly in the small colloidal and truly dissolved fractions. Especially below 10 cm depth, association with large Fe/Al/organic colloids was considered to be a precursor to the removal of U from the Dundrennan porewaters to the solid phase. In contrast, the association of U with small organic colloids was largely responsible for inhibiting attenuation in the Eskmeals soils.Lateral migration of U (and DU) through near-surface Dundrennan soils will involve both large and small colloids but, at depth, transport of the smaller amounts of U remaining in the porewaters may involve large colloids only. For one of the Dundrennan cores the importance of redox-related processes for the re-mobilisation of DU was also indicated as Mn^IV reduction resulted in the release of both Mn^II and U^VI into the truly dissolved phase.     

Measurement of plastic strain of polycrystalline material by electron backscatter diffraction

It is important to know the degree of plastic strain in order to evaluate the susceptibility and crack growth rate of stress corrosion cracking (SCC) in stainless steel and nickel based alloy, because SCC is enhanced by the cold work and causes many problems in nuclear power plant components. In this study, electron backscatter diffraction in conjunction with scanning electron microscopy is applied to measure the plastic strain imposed to stainless steel by tensile load. A new parameter, which quantifies the spread of the crystal orientation within individual grains arising due to dislocation accumulation during plastic deformation, is correlated with imposed plastic strain. The new parameter is called ‘crystal deformation’ and is determined from the spread in misorientation from the central grain orientation. It is confirmed that this parameter has a good correlation with plastic strain and is not affected by the data density of the crystal orientation map. The dislocation density distribution is also evaluated from the misorientation from the central orientation. Relatively high dislocation density was observed near grain boundaries and grain boundary triple points, which was consistent with the observed deterioration of EBSD pattern quality in those locations.     

Heparin-binding EGF-like growth factor mRNA is upregulated in the peri-infarct region of the remnant kidney model: in vitro evidence suggests a regulatory role in myofibroblast transformation

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a potent fibroblast and epithelial cell mitogen that may be important in wound healing. The aim of this study was to determine its distribution and possible function in segmental renal infarction. At day 1 postinfarction, in situ hybridization showed that HB-EGF mRNA was markedly increased by tubular epithelial cells bordering the infarcted zone. At day 3, typical myofibroblasts expressing alpha-smooth muscle actin (alpha-SMA) were present in large numbers at the peri-ischemic border and, over succeeding days, were also seen within the infarcted area. Some of these cells expressed HB-EGF mRNA by in situ hybridization suggesting possible autocrine stimulation. Endothelial cells appeared to be more resistant to ischemia than tubules because some capillaries at the periphery of the infarct, surrounded by infarcted tubules, also expressed HB-EGF mRNA. The staining intensity of HB-EGF mRNA in individual tubules and endothelial cells was maximal at day 5 after infarction, although Northern blots of tissue from the peri-infarct area only showed significantly increased expression of HB-EGF mRNA at days 1 and 3, perhaps reflecting a smaller area of greater intensity of expression at day 5. Because tubular cells expressing high levels of HB-EGF mRNA were directly apposed to myofibroblasts, an attempt was made to determine whether HB-EGF contributed to upregulation of alpha-SMA by human fibroblasts. Although stimulation of the fibroblast cell line MRC-5 with transforming growth factor-beta1 (TGF-beta1) increased alpha-SMA, HB-EGF reduced expression. HB-EGF also strongly inhibited the increased expression of alpha-SMA due to TGF-beta1. Because HB-EGF is a potent fibroblast mitogen and TGF-beta is usually antiproliferative, this study suggests that HB-EGF may contribute to a local balance between fibroblast proliferation and differentiation into myofibroblasts during scarring.