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Testing conditions have been shown to influence the outcomes of microbiologically influenced corrosion (MIC) studies. Despite this there are only limited reports comparing the performance of different metal types in MIC studies using exactly the same test conditions. This makes it difficult to predict the relative performance of different materials in applications in which MIC may occur. In the present work, the microbiologically influenced corrosion of a range of ferrous and non-ferrous alloys have been studied under identical test conditions. Metal coupons were exposed to a relatively common MIC test arrangement consisting of the sulphate-reducing bacterium, Desulfovibrio desulfuricans, in modified Baar's medium for a period of 90 days under anaerobic conditions. The results showed accelerated corrosion of carbon steel and copper-nickel alloys in the biotic test condition (i.e. with bacteria) compared to abiotic test conditions. No evidence of corrosion, however, was observed on any of the stainless steels, Inconel or titanium alloys in either of the abiotic or biotic test conditions studied. [ABSTRACT FROM AUTHOR]

Microbiologically influenced corrosion (MIC) encompasses a complex suite of processes that can result in costly and dangerous acceleration of corrosion rates. However, the complexity of MIC, and the wide range of conditions in which it occurs in the natural environment, has resulted in researchers performing tests under a wide range of laboratory conditions. This scattergun approach can potentially lead to ambiguous results and can compromise the ability to compare data from different tests. Therefore there is a need for the corrosion community to develop more realistic and standardised approaches to laboratory-based testing. This paper seeks to illustrate the challenges by examining a range of test parameters that can influence the results of MIC studies, using Escherichia coli and carbon steel as a model system. The experimental parameters considered here include test media composition, immersion temperature, immersion time and medium replenishment. It is shown that each of these parameters can exert a significant effect on the outcome of the study, thus supporting the contention that more realistic testing procedures are required to develop a better understanding of MIC processes and ultimately allow predictive management of MIC. [ABSTRACT FROM AUTHOR]

A study of the effect of ferrous ions on the initial attachment of sulphate reducing bacteria (SRB) and subsequent corrosion of carbon steel has been performed. It was found that the initial bacterial attachment process is complex, depending upon time period investigated. Early stages (⩽60 min) of attachment showed no dependence on the iron level in the media. After 60 min, more attachment and exopolymer production was observed in iron rich medium compared to iron deficient medium. The results suggest that monitoring of ferrous ion levels might be helpful in detection of MIC attack by SRB. [ABSTRACT FROM AUTHOR]

Highlights: [•] E. coli attachment and corrosion of carbon steel was studied in various media. [•] The rate and magnitude at which bacteria attached was medium dependent. [•] Corrosion decreased in the biotic nutrient broth (NB) compared to abiotic NB. [•] Corrosion increased in the biotic minimal medium (MM) compared to abiotic MM. [•] The type and amount of carbon source in the media had a significant impact on MIC. [ABSTRACT FROM AUTHOR]

Hydraulic components used in the maritime environment suffer damage due to the effects of corrosion and marine biofouling accumulation. The application of engineered coatings can overcome these problems. This study investigated the corrosion and mechanical performance of novel high velocity oxygen fuel (HVOF) sprayed ceramic-metal composite coatings; i.e., WC-18 wt% Hastelloy C and WC-10 wt% Ni-5 wt% Cr, designed for the protection of marine hydraulic components. A conventional atmospheric plasma sprayed (APS) ceramic coating (i.e., Al 2 O 3 -40 wt% TiO 2) and uncoated Monel K500 substrate were tested for benchmarking purposes. The corrosion performance of the samples was assessed using a combination of laboratory-based tests (i.e., electrochemical polarization, neutral salt spray, hot water immersion) and field exposure tests by immersion in seawater. The mechanical properties of the samples were assessed via a drop-weight impact test and the tensile adhesion test. The results showed that the HVOF coatings exhibited better corrosion resistance and mechanical performance compared to the baseline APS ceramic coating and uncoated Monel K500 substrate. • Corrosion/mechanical properties of HVOF WC-based Ni binder coatings were studied. • HVOF coatings had excellent corrosion performance in seawater field exposure tests. • HVOF coatings have high impact strength than Monel or Al 2 O 3.40TiO 2 coating. • HVOF coatings have high adhesion strength compared to Al 2 O 3.40TiO 2 coating. • HVOF WC-based Ni binder coatings are suitable for use in maritime industry. [ABSTRACT FROM AUTHOR]

Optimization of the pre-ionization phase is a necessary step before switching to the main tokamak operation. Langmuir probe and optical emission spectroscopy are among the prime plasma diagnostic techniques to realize practically the changes that occurred in floating potential, electron temperature, electron number density, and impurity concentration. Triple Langmuir probe (TLP) collects the time-resolved plasma parameters to visualize the real-time evolution of the ECR heated pre-ionized hydrogen plasma zones. The temporal profiles of the floating potential, electron temperature, and number density show significant dependence on the hydrogen fill pressure. The sequential imaging of the electron cyclotron resonance (ECR) heated plasma zones displays their growth and progression. At lower fill pressure, plasma imaging illustrates the two distinctive ECR heated plasma zones corresponding to the first and second harmonics. The studies provide insights into the physics of preferential plasma heating in space and time-varying magnetic fields producing ECRH zones. [Display omitted] • Plasma heating with microwaves at electron cyclotron resonance frequencies. • Time-resolved triple-probe measurements in ECRH-assisted pre-ionization. • Optical spectrum analysis of the hydrogen plasma for H α, H β and impurity lines. • Sequential imaging of the ECR heated pre-ionized plasma zones. [ABSTRACT FROM AUTHOR]

There are many unicellular tiny organisms which can self-propel collectively through non-Newtonian fluids by means of producing undulating deformation. Example includes nematodes, rod shaped bacteria and spermatozoa. Here we use Taylor's swimming sheet model, with non-Newtonian fluid bounded with in a complex wavy walls of a two-dimensional channel. Oldroyd-4 constant fluid is approximated as cervical mucus and MHD effects are also considered. After utilizing lubrication and creeping flow assumption the reduced non-linear differential equation is solved (by implicit finite difference technique) so that it will satisfy the dynamic equilibrium condition for steady propulsion. For a special (Newtonian) case the expressions of swimming speed and flow rate are also presented. We also demonstrate that the rheological properties of non-Newtonian fluid can assist or resist the pack of micro-organisms (swimming sheet), while the larger undulation amplitude in swimmer's body and magnetic field in downward direction can enhance the propulsion speed. The solution obtained via implicit finite difference method is also validated by a built in MATLAB routine bvp-4c. This built in function is based on collocation technique. Moreover an excellent correlation is achieved for both numerical methods. [ABSTRACT FROM AUTHOR]

A newly developed spectroscopic system based on linear photodiodes array has been installed on upgraded Glass Spherical Tokamak (GLAST-III) for spatial as well as temporal characterization of hydrogen discharge through light emission. The Spectral range of each silicon photodiode is from 300 nm to 1100 nm with response time of 10 ns and active area of 5 mm 2 (circular). The light from the plasma is collected through holes along 4 lines of sight channels with spatial resolution of about 5 cm passing from entire poloidal cross section. The photodiode's signals located at position of 10 and 14 cm from inboard side show fluctuations in the central plasma region. Moreover, the sequence of plasma lighting shows that plasma instigates from the central resonant field region and then expands outwards. At lower pressure, outboard movement of the plasma is slower suggesting better plasma confinement. In addition to photodiode array, an Ocean spectrometer (HR2000+) has been used to record the visible spectrum over the selected range (597–703 nm) with a spectral resolution of 0.15 nm. The studies have been conducted during initial phase of plasma formation for two different hydrogen gas fill pressures. Langmuir triple probe (LTP) is used to get time-resolved information on plasma parameters in the edge region. The time evolution of whole discharge including microwave pre-ionization phase and current formation phase has been demonstrated by temporal profiles of light emission and plasma floating potential. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the efficacy of a modified live Mycoplasma gallisepticum vaccine (GT5) for the protection of chickens against infection and respiratory disease. GT5 was constructed by the reconstitution of the avirulent high passage R (Rhigh) strain with the gene encoding the major cytadhesin GapA. GT5 expressed GapA on its surface yet retained the phenotypic characteristics of the parental Rhigh strain. Birds vaccinated with GT5 were protected upon challenge with the virulent low passage R (Rlow) strain as evidenced by a complete absence of tracheal lesions 2 and 4 weeks post-challenge, in contrast to sham immunized/challenged control birds. Modest amounts of IgG, and little, if any secretory IgA or IgM anti-M. gallisepticum were found in tracheal washings following vaccination. However, copious amounts of specific IgA were found following challenge, especially in sham immunized birds. This suggests that the tracheal IgG elicited by GT5 vaccination may have been responsible for blocking the initial colonization of Rlow, thereby resulting in protection. [Copyright &y& Elsevier]

Co-phthalocyanine molecules have wide range of optoelectronics and sensor applications. Motivated by the importance of this material, we studied the adsorption of CoPc thin to thick films on Au(111) surface by using ultraviolet photoelectron spectroscopy (UPS) coupled with angle resolved UPS (AR-UPS) and scanning tunnelling microscopy (STM). Molecular spectral emissions are found to be at 5.13, 7.94, and 10.32 eV below the Fermi level. Observed UPS and AR-UPS measurements show both changes and shifting in valence band features. The work functions of clean Au(111) surface and thick CoPc film are found circa 5.32 eV and 5.25 eV, respectively. Both the work function variation and shifting of molecular features dictate strong adsorbate-substrate interaction. AR-UPS measurements further illustrates that CoPc molecules lie flat on the Au(111) surface. Our STM results disclose that at sub-monolayer (Sub-ML, 0.4–0.8 ML) coverage and room temperature, CoPc molecules tend to adsorb in random fashions; which reveal a strong interaction at the CoPc-Au(111) interface. However, at the ML coverage and elevated temperature (~520K), long range pattern with the oblique structure is observed. Beyond ML coverage, existence of mixed phases consisting of well arranged patterns and molecular clusters have been observed. Overall, our STM results show that depending on the molecular thickness, CoPc molecules form three types of organized oblique, rectangular and square geometries which is consistent with the findings of CuPc and CoPc on Au(111) surface. Our findings may seek potential use in the organic molecular based electronic devices. • Thickness dependent electronic properties at the CoPc and Au(111) interface have been studied by means of UPS, ARUPS, and STM. • Valence level structures of CoPc molecules are found to be at 5.13, 7.94, and 10.32 eV below the Fermi level. • Work functions of the clean Au(111) surface and thick CoPc film are found to be 5.32 eV and 5.25 eV, respectively and IP of CoPc is found to be 5.89eV. • Angle resolved valence band (AR-UPS) measurements demonstrate that CoPc molecules lie flat on the adsorbate surface. • STM images reveal that CoPc molecules possess three packing arrangements, i.e. oblique, rectangular and square. [ABSTRACT FROM AUTHOR]