There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

http://sistemas.eel.usp.br/docentes/arquivos/2166002/1234Nb/Geetha-review2009.pdf

Ti based biomaterials, the ultimate choice for orthopaedic implants – A review

There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

This article presents an overview of the developments in stainless steels made since the 1990s. Some of the new applications that involve the use of stainless steel are also introduced. A brief introduction to the various classes of stainless steels, their precipitate phases and the status quo of their production around the globe is given first. The advances in a variety of subject areas that have been made recently will then be presented. These recent advances include (1) new findings on the various precipitate phases (the new J phase, new orientation relationships, new phase diagram for the Fe–Cr system, etc.); (2) new suggestions for the prevention/mitigation of the different problems and new methods for their detection/measurement and (3) new techniques for surface/bulk property enhancement (such as laser shot peening, grain boundary engineering and grain refinement). Recent developments in topics like phase prediction, stacking fault energy, superplasticity, metadynamic recrystallisation and the calculation of mechanical properties are introduced, too. In the end of this article, several new applications that involve the use of stainless steels are presented. Some of these are the use of austenitic stainless steels for signature authentication (magnetic recording), the utilisation of the cryogenic magnetic transition of the sigma phase for hot spot detection (the Sigmaplugs), the new Pt-enhanced radiopaque stainless steel (PERSS) coronary stents and stainless steel stents that may be used for magnetic drug targeting. Besides recent developments in conventional stainless steels, those in the high-nitrogen, low-Ni (or Ni-free) varieties are also introduced. These recent developments include new methods for attaining very high nitrogen contents, new guidelines for alloy design, the merits/demerits associated with high nitrogen contents, etc.

Recent developments in stainless steels

AISI type 304 stainless steel (SS) specimens in solution annealed and cleaned and passivated conditions were exposed to laboratory culture of Leptothrix sp. Epifluorescence studies and total viable count analysis of these specimens showed that bacterial density and biofilm coverage were the least on cleaned and passivated SS surfaces. To confirm whether MnS inclusions play a role in this, adhesion studies at applied potentials, surface characterisation studies using SEM and EDAX analysis and pitting studies with ferric chloride were carried out. These studies clearly revealed the removal of MnS inclusions. This removal leads to a significant reduction in the adhesion of Leptothrix sp. The significance of the present study is that pretreatment of SS by cleaning and passivation inhibited the adhesion of Leptothrix sp. This reduction in adhesion is responsible for the increased corrosion resistance of SS under biofilms in aqueous environments.

Inhibition of manganese oxidising bacterial adhesion on pretreated stainless steel surfaces

The effect of nitrogen on the corrosion resistance of 304LN SS containing 0.132, 0.193 and 0.406 wt-% N was investigated in 1M, 4M and 8M nitric acid and simulated high level waste (HLW) using electrochemical noise (EN) technique. Statistical, spectral, shot noise and wavelet methods were employed for EN analysis. Noise resistance and spectral noise resistance increased, while characteristic frequency decreased with increase in nitrogen content, implying lower corrosion activity with increase in nitrogen content. The cumulative probability plots obtained from shot noise analysis showed a shift towards lower frequency with increase in nitrogen content, and toward higher frequency with increase in concentration of nitric acid. Wavelet analysis of current noise was used for deriving mechanistic information. Micro laser Raman studies were carried out for passive film analysis. The results are detailed in the manuscript.

Effect of nitrogen on corrosion behaviour of 304LN SS in nitric acid and simulated high level waste by electrochemical noise

The influence of the microstructures of the base metal and weld metals on the wear and tribocorrosion properties of 304L stainless steel (SS) welds prepared by Manual Gas Tungsten Arc Welding (M-GTAW) and Activated Flux Gas Tungsten Arc Welding (A-GTAW) processes are reported. Increase in sliding speed increased both friction forces as well as wear rate. Higher hardness in M-GTAW weld metal resulted in increased wear resistance than A-GTAW weld metal and base metal. The inferior wear resistance of the base metal was due to the strain hardening behaviour under sliding condition. The polarization curves showed increase in passive current density under sliding condition. The applied potential was found to influence the tribocorrosion resistance of the material. Under tribocorrosion condition, the total material loss was higher in base metal followed by A-GTAW weld metal and M-GTAW weld metal. Characterization of worn surface by SEM indicated a mixed wear mechanism of abrasive and adhesive wear. The worn surf...

Wear and tribocorrosion behaviour of 304L stainless steel welds

(2003) Surface modification and engineering for nuclear industry Surface Engineering: Vol 19, No 5, pp 321-322

Surface modification and engineering for nuclear industry

Titanium is known for excellent corrosion resistance for the sea water-cooled condenser material but susceptible to biofilm formation and bio-fouling, leading to deterioration in the heat transfer properties. Present study involves an attempt to use nanotechnology based surface modification of titanium to improve the antibacterial property and thereby resistance to biofouling. Synthesis of zinc oxide (ZnO) nano structures on Ti by a simple wet chemical method was achieved with the formation of nano structures under mild conditions in the absence of any seed, catalysts or surfactants. These nano structures were characterized using Field emission scanning electron microscopy which showed nano needle like structures. Grazing Incidence X-ray diffraction pattern showed a Wurtzite phase ZnO with strong peak at (002), indicating nano structure growth along the c-axis. Laser Raman Spectroscopy studies also confirmed the presence of Wurtzite crystals of ZnO nano structures. The antibacterial activity of these ZnO coatings with respect to gram negative bacteria, Pseudomonas aeruginosa sp. was investigated qualitatively and quantitatively. Epifluorescence microscopy and total viable count analysis have confirmed that ZnO nanostructures on the titanium substrate provided antibacterial activity against Pseudomonas aeruginosa.

U. Kamachi Mudali

Papers

Inhibition of manganese oxidising bacterial adhesion on pretreated stainless steel surfaces

Effect of nitrogen on corrosion behaviour of 304LN SS in nitric acid and simulated high level waste by electrochemical noise

Wear and tribocorrosion behaviour of 304L stainless steel welds

Surface modification and engineering for nuclear industry

Active Nano Metal Oxide Coating for Bio-fouling Resistance