Comparative investigation into the corrosion of different bronze alloys suitable for outdoor sculptures

Several bronze alloys, suitable for production of outdoor sculptures, were developed in the frame of the European project “Eurocare-Bronzart”. The elemental composition of the alloys was searched to fulfil specific criteria such as: reduction of lead content, good resistance toward corrosion and aesthetic characteristics conformable to artistic purposes. After metallurgical characterization, the resistance toward corrosion was evaluated in artificial environments. Ageing experiments were performed in a salt spray cabinet and in a climatic chamber in the presence of a controlled concentration of SO₂. The Thin Layer Activation (TLA) method was applied to calculate the thickness loss of activated specimens exposed to artificial corrosive atmospheres. After artificial ageing experiments the surface of the materials was investigated by SEM-EDS techniques.The bronze alloys containing different percentage of nickel showed the best properties of resistance toward corrosion.     

BUCKLING BEHAVIOR OF LONG ANISOTROPIC PLATES SUBJECTED TO RESTRAINED THERMAL EXPANSION AND MECHANICAL LOADS

An approach for synthesizing buckling results and behavior for thin balanced and unbalanced symmetric laminates that are subjected to nondestabilizing mechanical preloads, uniform heating or cooling, and elastically or totally restrained axial thermal expansion or contraction is presented. This approach uses a nondimensional analysis for infinitely long, flexurally anisotropic plates that are subjected to combined loads and is based on useful nondimensional parameters. In addition, a stiffness-weighted laminate coefficient of thermal expansion is derived and used to determine critical temperatures in terms of physically intuitive mechanical buckling coefficients, and the effects of membrane orthotropy and membrane anisotropy are included. Many results are presented for some common laminates that are intended to facilitate a structural designer's transition to the use of the generic buckling design curves that are presented in the article. Several generic buckling design curves are presented that provide physical insight into the buckling response in addition to providing useful design data. Examples are presented that demonstrate the use of the generic design curves. The analysis approach and generic results identify the effects and characteristics of laminate thermal expansion, membrane orthotropy and anisotropy, and flexural orthotropy and anisotropy in a very general and unifying manner.     

EURAMET.T-K7 Key Comparison of Water Triple-Point Cells

The results of a EURAMET key comparison of water triple-point cells (EURAMET.T-K7) are reported. The equipment used, the measuring conditions applied, and the procedures adopted for the water triple-point measurement at the participating laboratories are synthetically presented. The definitions of the national reference for the water triple-point temperature adopted by each laboratory are disclosed. The multiplicity of degrees of equivalence arising for the linking laboratories with respect to the ??mother?? comparison CCT-K7 is discussed in detail.     

Experimental performance of adaptive beamforming in a sonarenvironment with a towed array and moving interfering sources

The performances of adaptive array algorithms are known to suffer from a strong degradation in scenarios with moving interfering sources. In this article, basic adaptive beamforming techniques are compared using shallow sea sonar data recorded in a towed horizontal array environment with moving interfering sources originated from shipping noise. Our experimental results show the relationship between the practical performances of adaptive and conventional beamforming techniques compared in terms of output SINR or a related measure given by the noncompensated postbeamforming interference power. These results demonstrate noticeable performance improvements that can be achieved using several robust algorithms relative to traditional adaptive beamforming schemes     

Current Status and Trends in Muskegon Lake,Michigan

A long-term monitoring program was initiated in 2003 to determine the ecological status of Muskegon Lake, a Great Lakes Area of Concern. This paper presents data generated from the first 3 years of the monitoring program, discusses how the data are being used to establish and justify lake restoration targets, and assesses how water quality conditions have changed over time. Between 1972 and 2005, lake-wide averages of total phosphorus and soluble reactive phosphorus from the water surface have declined from 68 to 27 μg/L and from 20 to 5 μg/L, respectively. In addition, average chlorophyll a concentrations have declined from 25 to 6 μg/L over this period, while Secchi disk depths have increased from 1.5 to 2.2 m. Wastewater diversion, and perhaps dreissenid filtering activity, is most likely responsible for these changes. However, nitrate concentrations have increased from 70 to 270 μg/L over the same time period. During 2003–2005, phytoplankton abundance and fish catch were lower in the spring compared to the summer and fall. Microcystis was the most abundant phytoplankton genus; the fish community generally was dominated by round goby (Neogobius melanostomus) in spring and summer, and sunfishes (Centrarchidae) in the fall. Dreissenid abundance was highly variable over time, but densities were low relative to Saginaw Bay. Approximately 65% of the Muskegon Lake shoreline has been hardened (i.e., physically altered). Overall, the water quality of Muskegon Lake has improved over the past 30 years, but environmental challenges still exist, including contaminated sediments, loss of natural habitat, and invasive species.     

Time-dependent changes in the density and hemoglobin F content of biotin-labeled sickle cells

Sickle red blood cells (RBC) are subject to a number of important cellular changes and selection pressures. In this study, we validated a biotin RBC label by comparison to the standard 51Cr label, and used it to study changes that occur in sickle cells as they age. Sickle RBC had a much shorter lifespan than normal RBC, but the two labels gave equivalent results for each cell type. A variable number of sickle, but not normal, RBC disappeared from the circulation during the first few hours after reinfusion. The number of biotinylated sickle reticulocytes was decreased by 50% after 24 h and 75% after 48 h, with a gradual decrease in the amount of reticulum per cell. The labeled sickle cells exhibited major density increases during the first 4-6 d after reinfusion, with smaller changes thereafter. A small population of very light, labeled sickle RBC was essentially constant in number after the first few days. Fetal hemoglobin (HbF) content was determined in isolated biotinylated sickle RBC after reinfusion, allowing an estimate of lifespan for RBC containing HbF (F cells) and non-F cells. The lifespan of sickle biotinylated RBC lacking HbF was estimated to be approximately 2 wk, whereas F cells survived 6-8 wk.     

Short-term effects of early-acting and multilineage hematopoietic growth factors on the repair and proliferation of irradiated pure cord blood (CB) CD34+ hematopoietic progenitor cells

PURPOSE: Hematopoietic growth factor(s) (GF) may exert positive effects in vitro or in vivo on the survival of hematopoietic stem and progenitor cells after accidental or therapeutic total body irradiation. METHODS AND MATERIALS: We studied the clonogenic survival and DNA repair of irradiated (0.36, 0.73, and 1.46 Gy) CD34+ cord blood (CB) cells after short-term incubation (24 h) with GFs. CD34+ cells were stimulated with basic fibroblast growth factor (bFGF), stem cell factor/c-kit ligand (SCF), interleukin-3 (IL-3), IL-6, leukemia inhibitory factor (LIF), and granulocyte-monocyte colony stimulating factor (GM-CSF) alone or in combination in short-term serum-free liquid suspension cultures (LSC) immediately after irradiation and then assayed for clonogenic progenitors. DNA repair was evaluated by analysis of DNA strand breaks using the comet assay. Survival of CFU-GM, BFU-E, and CFU-Mix was determined and dose-response curves were fitted to the data. RESULTS: The radiobiological parameters (D[0] and n) showed significant GF(s) effects. Combination of IL-3 with IL-6, SCF or GM-CSF resulted in best survival for CFU-GM BFU-E and CFU-Mix, respectively. Combinations of three or more GFs did not increase the survival of clonogenic CD34+ cells compared to optimal two-factor combinations. The D[0] values for CFU-GM, BFU-E, and CFU-Mix ranged between 0.56-1.15, 0.41-2.24, and 0.56-1.29 Gy, respectively. As for controls, the curves remained strictly exponential, i.e., all survival curves were strictly exponential without any shoulder (extrapolation numbers n=1 for all tested GF(s). DNA repair capacity of CD34+ cells determined by comet assay, was measured before, immediately after irradiation, as well as 30 and 120 min after irradiation at 1 Gy. Notably, after irradiation the 2-h repair of cytokine-stimulated and unstimulated CD34+ cells was similar. CONCLUSION: Our data indicate that increased survival of irradiated CB CD34+ cells after short-term GF treatment is mediated through proliferative GF effects on the surviving fraction but not through improved DNA repair capacity.