Bacterial corrosion of metals. II. Gravimetric investigations of the corrosion of nonferrous metals

The specific kinetic features of the bacterial corrosion of AK-4, AK-6, Д-16л, Д-16п, AMц-8 aluminum alloys; MA-8 magnesium alloy; and БpAЩMц 10-3-1.5 bronze were investigated with the use of tropical strains of bacteria. The protective effectiveness of anodic-oxide coatings applied to aluminum alloys, and that of TsIATIM-221 and AMG-10 compositions were also tested under these conditions.     

Optical properties of polyfluorene–thiophene copolymers having chiral side chains

A series of alternating copolymers consisting of chiral thiophene and fluorene, poly[9,9-dihexylfluorene-alt-(3-{2-[(S)-(+)-1-methyloctyloxy]ethyl}thiophene)] (P1), and poly[9,9-dihexylfluorene-alt-(3-{2-[(S)-(+)-1-methyloctyloxy]ethyl}-2,2′-bithiophene)] (P2), were synthesized by Suzuki coupling method. P1 and P2 were characterized by ¹H NMR spectra and elemental analyses. Both of the copolymers showed clear solvatochromism and circular dichroism in methanol/chloroform mixed solutions. These two polymers had different spacer lengths between the chiral side chains along the main chain, and accordingly the circular dichroism spectra were apparently different.     

The properties of melt-textured superconductors

Melt-textured rare earth-Ba-Cu-O has significant potential for industrial applications, particularly for high-field applications. This article summarizes the flux-pinning, magnetic, and trapped-field properties of melt-textured RE-Ba-Cu-O. For more information, contact M. Murakami, Superconductivity Research Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo 105-0023 Japan; telephone 81-3-3454-9284; fax 81-3-3454-9287; e-mail murakami@istec.or.jp.     

On the role of B4C on hardness and toughness of TiCN - SiC - TiN -Cr3C2 - Co cermet

This paper reports the development of TiCN - SiC- TiN - Cr₃C₂ - Co cermet modified with B₄C for cutting tool applications. Cermets of three different composition with varying B₄C in TiCN - SiC - TiN - Cr₃C₂ - Co were fabricated for a study of addition of B₄C on hardness and toughness. The cermet pellets were sintered using Spark Plasma Sintering (SPS) at 50 MPa pressure, 1500 °C temperature at a heating rate of 100 °C/min with 10mins soaking with pulse rate of 12/2 ms. Microstructure examination revealed a typical core-rim structure. Vickers hardness test was done at a load of 30 kg and duration of 10s. Fracture toughness was computed using crack length data measured from the hardness test. The cermet with composition 65% TiCN - 15% SiC - 5% TiN - 5% Cr₃C₂–10% Co showed high hardness of 16.2 GPa and toughness of 10.7 MPa √m and 50% TiCN - 15% SiC - 5% TiN - 5% Cr₃C₂–10% Co - 15% B₄C exhibited high fracture toughness of 16.5 MPa √m with hardness value of 12 GPa. The addition of B₄C greatly enhanced the toughness value and reduced the hardness value slightly.     

Effect of Process Parameters on the Structure and Properties of Galvanized Sheets

The effect of galvanizing parameters on the structure (spangle size and coating microstructure) and properties (formability and corrosion resistance) of galvanized sheets was studied in a hot dip process simulator (HDPS) in a conventional Pb bearing (0.08-0.10%) zinc bath by varying zinc bath Al level (0.10-0.28%), bath temperature (718-743 K), dipping time (1.5-3.5 s), wiping gas flow rate (200-450 lpm), nozzle distance (15-17 mm) and wiping delay time (0.1-2.1 s). Al level in the range of 0.18-0.24% in combination with dipping time of 1.5-2.5 s and bath temperature of 718-733 K results in superior formability (E _cv: ~9.3 mm) of the composite (thickness: 0.8 mm). High post-dip cooling rates (~25 K/s) suppress spangle growth (spangle size: ~2 mm). The spangle size of the GI sheet strongly influences the corrosion rate which increases from 5.8 to 9.2 mpy with a decrease in spangle size from 17.5 to 3 mm. By controlling the Al level (0.20%) in zinc bath and bath temperature (733 K), the corrosion rate of mini-spangle GI sheet can be controlled to a level of 5.5 mpy.     

Synthesis and electro-optical properties of biphenyl analogues

Three emitting materials containing a biphenyl core connected at both ends with phenoxazine or anthracene groups, 10-(3-(10H-phenoxazin-10-yl)-6-phenylphenanthridin-8-yl)-10H-phenoxazine (DPoPP), 8-(anthracen-10-yl)-3-(anthracen-9-yl)-6-phenylphenanthridine (DAnPP), and 2-(anthracen-10-yl)-7-(anthracen-9-yl)-4,5,9,10-tetrahydropyrene (DAnTP) were synthesized via the C–N Ullmann coupling or C–C Suzuki-coupling reaction. Optical properties, thermal stabilities and molecular orbital energies were analyzed as a function of their molecular microstructure. The thermal stabilities of them were influenced by biphenyl core. On the other hand, their emissions were primarily affected by anthracene or phenoxazine end groups. Two compounds with anthracene moiety at both ends showed electronic band structures suitable for host materials for reported blue dopants. The double-layer OLED (organic light-emitting diode) devices, ITO/NPD/synthesized material/LiF/Al, containing the synthesized materials as emitting layer emitted yellowish-green (DPoPP), greenish-blue (DAnPP) and blue (DAnTP).     

Co-sensitization with near-IR absorbing cyanine dye to improve photoelectric conversion of dye-sensitized solar cells

Two carboxylated cyanine dyes, 3-butyl-2-[3-(1-butyl-5-carboxy-1,3-dihydro-3,3-dimethyl-2H-indol-2-ylidene)-1-propen-1-yl]-1,1-dimethyl-7-[1-[2-[6-(4-morpholinyl)-1,3-dioxo-1H-benz[de]isoquinolin-2(3H)-yl]ethyl]-1H-1,2,3-triazol-4-yl]-1H-Benz[e]indolium iodide (A), 2-[5-(1-butyl-5-carboxy-1,3-dihydro-3,3-dimethyl-2H-indol-2-ylidene)-1,3-pentadienyl]-3-ethyl-1,1-dimethyl-1H-Benz[e]indolium iodide (B), have been prepared and their photophysical and electrochemical properties have been investigated. A, B and their mixtures (AB) were used as sensitizers in nanocrystalline TiO₂ solar cells to improve photoelectric conversion efficiency. It was found that the solar cell sensitized with A3B1 (molar ratio: A:B = 3:1) generated a high power conversion efficiency of 3.0% under AM1.5G illumination (100 mW cm⁻²), indicating that co-sensitization is a promising method to improve the photoelectrical properties of dye-sensitized solar cells.     

Photoluminescent and electroluminescent properties of DCM-1 dispersed poly(p-phenylene vinylene) derivatives

The single layer devices utilizing poly[2-(carbazol-9-yl)-5-(2-ethylhcxyloxy)-1,4-phenylene vinylene] (CzEh-PPV) and poly[2-{4-[5-(4-tert-butylphenyl)-l,3,4-oxadiazolyl]-phenyl}-5-(2-ethythexyloxy)-l,4-phenylene vinylene] (OxdEh-PPV) doped with varying weight percent of 4-(dicyanomethylene)-2-methyl-6-[p-(dimethylamino)styryl]-4H-pyran (DCM-1) were fabricated and their photo luminescence (PL) and electroluminescence (EL) properties were discussed in this investigation. The PL spectra of DCM-1 doped polymers show that the emission is mostly from DCM-1 and Förster energy transfer may occur between DCM-1 and the two polymers. On the other hand, field-dependence of the emission spectra of EL devices was observed in detail. For the CzEh-PPV/DCM-1, the emission at the wavelength of 534 nm remains unchanged as the level of DCM-1 increases, whereas the peak at 572 nm is intensified with increasing both the additive level and applied electric field. For the OxdEh-PPV/DCM-1, the main peak is red-shift as the level of DCM-1 increases and blue-shift as the applied electric field does.     

Effect of aging time on corrosion inhibition of cationic surfactant on mild steel in sulfamic acid cleaning solution

The stability of the 1 M sulfamic acid solutions containing a gemini cationic surfactant (12-4-12) or its monomeric counterpart (DTAB) during 23 days of storage were studied by electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD) and surface tension measurements. The EIS studies indicated that in comparison to DTAB solution, 12-4-12 solution considerably retained the corrosion inhibition during the storage period. The surface tension of DTAB solution was increased around 10 mN/m during storage while the surface tension of 12-4-12 solution was almost unchanged. The higher stability of 12-4-12 acidic solution than that of DTAB was also depicted by XRD results.     

The twin-roll strip casting of magnesium

Commonwealth Scientific & Industrial Research Organization has been working since 2000 to develop twin-roll strip casting of magnesium alloy. The primary objective was to significantly reduce the manufacturing cost of the magnesium sheet through the twin-roll casting process. This article describes the goals and challenges of this project as well as pilot plant test results. For more information, contact D. Liang, CSIRO Manufacturing & Infrastructure Technology, Normanby Road, Clayton, Victoria 3168, Australia; +61-3-9545-2981; fax +61-3-9544-1128; e-mail daniel.liang@csiro.au.     

Thermodynamics of chemical and electrochemical stability of brasses

Based on the theory of “regular” solutions, the thermodynamic properties of α-, β-, γ-, ɛ-, and η-phases of the Cu-Zn system are described. The surface activity of the elements in the phases is assessed. Potential-pH diagrams for the general system Cu-Zn-H₂O and the manganese brass system H₂O at 25°C are plotted. The nature of passivating films on conventional and special brasses and their composition are elucidated in different pH and potential ranges.     

Synthesis and luminescence properties of rare earth ternary complexes consisting of Tb(III), β-diketones and 1,10-phenanthroline (phen)

In order to study the luminescent properties of ternary rare earth complexes with β-diketone ligand, three new β-diketone ligands, 1-phenyl-3-(p-phenylethynylphenyl)-1,3-propanedione(HPPP), 1-(2-thienyl)-3-(p-phenylethynylphenyl)-1,3-propanedione (HTPP) and 1-(2-furyl)-3-(p-phenylethynylphenyl)-1,3-propanedione (HFPP), were synthesized by Sonogashira coupling reaction and Claisen condensation. Three new ternary rare earth complexes, TbL₃phen (L = PPP, TPP, or FPP), were synthesized by the reaction of rare earth chloride TbCl₃,1,10-phenanthroline (phen) with HPPP, HTPP, or HFPP respectively, in alcohol solution. The compositions were characterized by means of elemental analysis, chemical analysis, and IR spectra. Luminescent properties of the three new complexes have been studied. The results show that the ternary Tb(III) complexes only emit the weak fluorescence of the Tb(III) ion, which reveals the triplet state energy of the ligands does not match well with the excited state vibrating energy of Tb³⁺ ion.     

中枢σ-2受体对神经精神疾病影响和治疗的研究进展

中枢σ-2 受体可能在神经精神疾病的发病和治疗中起重要作用。近年来,随着新型σ-2受体选择性配体的问世,其神经生物学相关研究取得了长足进展。最新研究发现,孕激素受体膜组分1（progesterone receptor membrane component 1,PGRMC1）可能是σ-2受体的一部分,这为σ-2受体的功能研究提供了新方向。因此,本文就σ-2受体在神经系统中的生理功能,以及σ-2受体对神经精神疾病的影响和治疗的相关研究进展作一综述。     

Inhibition effects of some Schiff’s bases on the corrosion of mild steel in hydrochloric acid solution

The corrosion inhibition effect of 4-{[(1Z)-(2-chloroquinolin-3-yl)methylene]amino} phenol (CAP), N-[(1Z)-(2-chloroquinolin-yl)methylene]-N-(4-methoxyphenyl)amine (CMPA) and N-[(1E)-(2-chloroquinolin-3-yl)methylene]-N-(4-nitrophenyl)amine (CNPA) on mild steel in 1.0 M HCl has been investigated using mass loss, polarization and electrochemical impedance techniques at 300 K. The inhibition efficiencies increased with increase in inhibitors concentration. Polarization studies showed that the inhibitors are of predominantly cathodic character. Among the three compounds studied, CAP exhibited the best performance giving more than 97% IE. Some samples of mild steel were examined by SEM. All the inhibitors were found to adsorb on the mild steel surface according to the Langmuir adsorption isotherm.     

Microstructure and Properties of Cast B-Bearing High Speed Steel

Microstructure, mechanical properties, and wear resistance of B-bearing high-speed steel (HSS) roll material containing 0.90-1.00% C, 1.3-1.5% B, 0.8-1.5% W, 0.8-1.5% Mo, 4.6-5.0% Cr, 1.0-1.2% V, and 0.15-0.20% Ti were studied by means of the optical microscopy (OM), the scanning electron microscopy (SEM), x-ray diffraction (XRD), hardness, impact toughness, and pin-on-disk abrasion tests. The results showed that as-cast structure of B-bearing HSS consisted of α-Fe-, M₂₃(B,C)₆-, M₃(B_0.7C_0.3)-, and M₂(B,C)-type borocarbides, a small quantity of retained austenite, and a small amount of TiC. The hardness and impact toughness values of as-cast B-bearing HSS reached 65-67 HRC and 80-85 kJ/cm², respectively. There were many M₂₃(B,C)₆-precipitated phases in the matrix after tempering, and then, with increasing temperature, the amount of precipitated phases increased considerably. Hardness of B-bearing HSS gradually decreased with the increasing tempering temperature, and the change of tempering temperature had no obvious effect on impact toughness. B-bearing HSS tempered at 500 °C has excellent wear resistance, which can be attributed to the effect of boron.     

The practice and characterization of historic fire gilding techniques

Fire gilding was the predominant technique for the gilding of metalwork from 300 b.c. in China and 200 a.d. in Europe until the invention of electroplating in the 19th century. This article investigates its metallurgical aspects based on studies of original objects, gilding replication experiments, and literary evidence. Author’s Note: All compositions are in weight percent. The artifact appearing on this page is a 6th–7th century Anglo-Saxon cruciform brooch of fire-gilded low-tin bronze. A fire-gilded copper Chinese garment hook with a turquoise inlay from c. 200 b.c. is shown on page 60; three Chinese garment hooks of fire-gilded and silvered copper with turquoise in lay appear on page 61. Fore more information, contact K. Anheuser, Staatliche Museen Berlin, Schlosstr. la, D-14059, Berlin, Germany, telephone 49-30-320-91-298; fax +49-30-322-16-14.     

Synthesis and antimicrobial activities of gold(I) sulfanylcarboxylates

Reaction of NaAuCl₄·H₂O and thiodiglycol (1:3 molar ratio) with 3-(aryl)-2-sulfanylpropenoic acids, H₂ xspa = [x:p = 3-phenyl-, f = 3-(2-furyl)-, t = 3-(2-thienyl)-, o-py = 3-(2-pyridyl)-, Clp = 3-(2-chlorophenyl)-, -o-mp = 3-(2-methoxyphenyl)-, -p-mp = 3-(4-methoxyphenyl)-, -o-hp = 3-(2-hydroxyphenyl)-, -p-hp = 3-(4-hydroxyphenyl)-, diBr-o-hp = 3-(3,5-dibromo-2-hydroxyphenyl)] and 2-cyclopentylidene-2-sulfanylacetic acid (H₂cpa) in a 1:1 metal/ligand molar ratio gave compounds of the type [Au(Hxspa)] or [Au(Hcpa)]. These compounds were reacted with diisopropylamine to afford [HQ][Au(xspa)] or [HQ][Au(cpa)] (HQ = diisopropylammonium) and with NaOH to afford Na[Au(xspa)]·H₂O and Na[Au(cpa)]·H₂O. All of the new compounds were isolated and characterised by IR and ¹H and ¹³C NMR spectroscopy. The antimicrobial activities of the complexes against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albicans, Pseudomonas aeruginosa and carbapenem-resistant P. aeruginosa were evaluated and compared to those of the equivalent silver(I) complexes. The comparison shows that the gold compounds generally show better activity than the silver analogues against S. aureus and B. subtilis, but low sensitivity against E. coli, P. aeruginosa and C. albicans, suggesting a different mode of antimicrobial action for equivalent silver and gold compounds.     

X-Ray Diffraction Determination of The Coefficients of Expansion of Alpha Uranium

The unit cell dimensions of orthorhombic uranium have been determined over the temperature range —253° to 640°C. Above room temperature (27°C), these data were found to fit the equations at = a27 [1 + 17.2 × 10-6 (t —27) + 30.8 × 10-9 (t — 27)2] bt = b27[1 — 9.2 × 10-6 (t —27) + 40.4 × 10-⁹ (t —27) 2 — 67.5 × 10-12 (t —27)3] ct = c27[1+25.1 × 10-⁶ (t —27) — 21.3 × 10-9 (t —27)2 + 57.5 × 10-12 (t —27)3]. Mean coefficients were computed. Over the range —253° to 100°C, these were compared with dilatometer data.     

Protection of carbon steel against corrosion in hydrochloric acid solution by some synthesized cationic surfactants

A series of some cationic surfactants was synthesized namely: N,N,N-tris(hydroxymethyl)-2-oxo-2-(2-(2-(dodecanoyloxy)ethoxy)ethoxy)ethanaminium chloride (DDAC); N,N,N-tris(hydroxymethyl)-2- oxo-2-(2-(2-(tetradecanoyloxy) ethoxy) ethoxy) ethanaminium chloride (TDAC) and N,N,Ntris( hydroxymethyl)-2-oxo-2-(2-(2-(hexadecanoyloxy)ethoxy)ethoxy)ethanaminium chloride (HDAC). Their chemical structures were characterized using FTIR and ¹HNMR spectroscopy. Corrosion inhibition performance of these compounds on carbon steel in 0.5 M HCl was studied using weight loss and potentiodynamic polarization methods. It was seen that the three synthesized cationic surfactants decreased the corrosion rate of mild steel in acidic medium due to the adsorption on the metal surface. And it was found that the inhibition efficiency increased with increasing the inhibitor concentration. The adsorption of inhibitors on the carbon steel surface obeys modified Langmuir equation which named Villamil isotherm adsorption. Polarization curves show that the synthesized inhibitors are mixed-type inhibitors in 0.5 M HCl. ΔG_ads⁰ were ranged from–31.65 to–33.40 kJ mol^–1 which indicate that the adsorption process is mixture between physical and chemical adsorption.     

The computer-based study of multicomponent slag viscosities

A software has been developed to calculate the viscosities of multicomponent oxide slags using a viscosity model. The software is linked to a viscosity database, which contains the model parameters and the experimental data, along with their sources. The model parameters have been optimized based on experimental data generated in the laboratory and found in the literature. The model parameters enable the calculation of the viscosities of six-component Al ₂ O ₃-CaO-Fe _n O-MgO-MnO-SiO ₂ slags as well as its subsystems as functions of temperature and composition. For more information, contact S. Seetharaman, Royal Institute of Technology, Department of Metallurgy, 10044 Stockholm, Sweden; telephone 46-8-790-8355; fax 46-8-790-0939; e-mail seeth@metallurgi.kth.se.