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Antibacterial activities of gold and silver nanoparticles against Escherichia coli and bacillus Calmette-Guérin
No full textBackground: Diseases such as tuberculosis (TB) have always had a large impact on human health. Bacillus
Calmette-Guérin (BCG) is used as a surrogate for TB during the development of anti-TB drugs. Nanoparticles (NPs)
have attracted great interest in drug development. The purpose of this study was to examine the potential of NPs
as anti-TB compounds by studying the interacting mechanisms between NPs and bacteria.
Results: We investigated effects of gold and silver NPs on BCG and Escherichia coli. Experimentally, particle size and
shape were characterized using transmission electron microscopy (TEM). Different concentrations of NPs were
applied in bacterial culture. The growth of E. coli was monitored through colony forming units (CFU). The
mechanism of interaction between NPs and bacteria was analyzed through bacterial thin sections followed by TEM
and scanning electron microscopy. Antibacterial effects on BCG were observed by recording fluorescent protein
expression levels.
Conclusions: The results suggest NPs have potential applications as anti-TB compounds. The antibacterial effects
and mechanism of action for NPs were dependent upon composition and surface modifications
Giant Magnetoresistance in Electrodeposited Films: Current Status and the Influence of Parameters
No full textElectrodeposition of some alloys and multilayer which exhibits the giant magneto resistance
(GMR) effect, have been the subject of numerous studies. They have great potential for technological
applications, such as magneto resistive sensors and magnetic recording devices. GMR
effect is more usually seen in multilayer and alloys structure, when two magnetic layers are
closely separated by a thin non-magnetic spacer layer. This paper deals with the review of literature
available on electrodeposition of alloys and multilayer for GMR application. The effect
of thickness of magnetic, non-magnetic layers, number of bi-layers, electrolyte pH, electrolyte
temperature, additives and annealing process on GMR properties will be discusse
Electroless deposition of composite coatings containing kaolin nanoparticles
No full textThe ability to codeposit particulate matter in a matrix of electroless nickel has led to a new
generation of composite coatings with unique properties, such as high hardness wear, abrasion,
corrosion and high temperature oxidation resistance. In this paper, the authors report on the
development of electroless Ni–P–kaolin composite coating, and the characteristic properties of
the selected deposits were evaluated by scanning electron microscopy, energy dispersive X-ray
and X-ray diffraction techniques. A good rate of deposition of 12 mm h21 was observed for the
optimised concentration of 6 g L21 of kaolin in the bath. For the optimised bath composition and
operating conditions, the composite deposit was found to contain 81?7%Ni, 9?8%P and
10?5%kaolin. Heat treatment at 400uC for 1 h results in an increase in the hardness and wear
resistance of the composite coating. The corrosion resistance is also highly enhanced by the
incorporation of kaolin in the nickel–phosphorus matrix. The crystallite size of the composite
coating is 20 nm, and the codeposition of kaolin follows the Langmuir adsorption isotherm
Nanocomposite Ti–Si–N Coatings Deposited by Reactive dc Magnetron Sputtering for Biomedical Applications
No full textNanocomposite Ti–Si–N coatings were prepared by reactive dc
magnetron sputtering in a mixture of Ar and N2 gases onto bio
implantable 316L stainless steel substrates. X-ray diffraction
analysis revealed that the Ti–Si–N nanocomposite coatings are
mainly composed of amorphous Si3N4 and TiN crystals. The
presence of different phases like TiN, TiO2, and Si3N4 was
confirmed from X-ray photoelectron spectroscopy analysis.
Raman spectra of the as-deposited composite coatings exhibited
characteristic peaks at 207.5, 305.8, 442.5, and 571.8
cm
�1. HRTEM indicated columnar microstructure. A higher
hardness value of 35 GPa for the nanocomposite coatings was
observed. The potentiodynamic polarization and electrochemical
impedance spectroscopy measurements showed that the
Ti–Si–N nanocomposite coatings exhibited superior corrosion
resistance compared with the Si3N4, TiN single layer, and the
bare substrate in simulated body fluid solutio
High-Performing LiMgxCuyCo1−x−yO2 Cathode Material for Lithium Rechargeable Batteries
No full textSustainable power requirements of multifarious
portable electronic applications demand the development of
high energy and high power density cathode materials for
lithium ion batteries. This paper reports a method for rapid
synthesis of a cobalt based layered cathode material doped
with mixed dopants Cu and Mg. The cathode material exhibits
ordered layered structure and delivers discharge capacity of
∼200 mA h g−1 at 0.2C rate with high capacity retention of
88% over the investigated 100 cycle
Effect of the Surface Roughness of Conducting Polypyrrole Thin-Film Electrodes on the Electrocatalytic Reduction of Nitrobenzene
No full textConducting polypyrrole (PPy) thin-film
electrodes were prepared by the electropolymerization of
pyrrole on gold-coated glass plates. Films of various
roughnesses were obtained by the variation of the scan
rates during electropolymerization. These thin films were
modified by doping with 6mM of the dopant NiCl2. The
surface morphology of the films was studied by scanning
electron microscopy and atomic force microscopy (AFM),
which suggested films prepared with a high scan rate
were rougher in nature than the films produced with a
low scan rate. The electrocatalytic reduction of nitrobenzene
was carried out with these electrodes with the cyclic
voltammetry technique in acetonitrile containing 0.1M
HClO4 as a supporting electrolyte. The various results
obtained show that the conducting PPy thin-film electrodes
were catalytically active toward the electroreduction
process. The modified PPy film electrodes doped with
NiCl2 were more active toward nitrobenzene electroreduction
than the PPy film alone. The results indicate that the
roughness of the films played a very important role in
determining their catalytic activity. The PPy films that
were more rough in nature were catalytically more active
than the smooth films; this may have been due to the
availability of more reactive sites in the case of rough
films. The apparent diffusion coefficients of the PPy film
electrodes were also calculate
Electrochemically Prepared Manganese Oxide as a Cathode Material for a Microbial Fuel Cell
No full textElectrochemical corrosion and materials properties of reactively sputtered TiN/TiAlN multilayer coatings
No full textTiN/TiAlN multilayers of 2 mm thickness were successfully prepared by reactive DC magnetron sputtering method. XRD pattern showed the
(1 1 1) preferential orientation for both TiN and TiAlN layers. XPS characterization showed the presence of different phases like TiN, TiO2, TiON,
AlN and Al2O3. Cross sectional TEM indicated the columnar growth of the coatings. The average RMS roughness value of 4.8 nm was observed
from AFM analysis. TiN/TiAlN coating showed lower friction coefficient and lower wear rate than single layer coatings. The results of
electrochemical experiments indicated that a TiN/TiAlN multilayer coating has superior corrosion resistance in 3.5% NaCl solution
Highly sensitive detection of proteins using voltammetric assay in the presence of silver nanostructures
No full textA novel voltammetric protein assay has been demonstrated using bovine serum albumin in the presence
of silver nanostructures (AgNs) formed electrochemically on gold substrates modified by self-assembled
monolayer of thioctic acid. It is shown that the prepared AgNs exhibit voltammetric response characteristic
of Ag and shows near Nernstian response at physiological pH. The advantages of the electrochemical
assay compared to conventional protein analysis are the wide linear concentration range (10�4–10�11 g/
mL) and trace level detection limits (50 pg/mL). The result of this electrochemical analysis agreed well
with an independent spectrophotometric method using Bradford reagent, but the detection limit is far
superior using the electrochemical method. Further, the modified electrode exhibits high sensitivity
and long term stability. We invoke a new concept of surface enhanced activity of Ag+ ions at the electrochemical
interface by the negatively charged bovine serum molecule
Voltammetric investigations on the relative deactivation of boron-doped diamond, glassy carbon and platinum electrodes during the anodic oxidation of substituted phenols in room temperature ionic liquids
No full textDeactivation behaviour of boron-doped diamond (BDD) had been extensively studied for the first
time in three room temperature ionic liquids (RTILs) namely 1-ethyl-3-methyl imidazolium nonaflate
(EMIN), triethylmethylammonium methyl sulphate (TEMAMS) and N-hexyl-N,N,N-triethylammonium
bis(trifluoromethanesulfonyl)imide (N2226TFSI) along with glassy carbon (GC) and platinum (Pt) electrodes
on the anodic oxidation of 2,6-dimethylphenol (2,6-DMP), 2,4-dimethylphenol (2,4-DMP) and
3,4-methylenedioxyphenol (3,4-MDP) using cyclic voltammetry (CV). Voltammetric studies reveal that
the anodic potential limit of the electrodes decreases in the order GC > BDD > Pt in these media and EMIN
shows the highest anodic limit among the three RTILs. Multisweep CV studies suggest that the three
phenols show irreversible and reversible characteristics on the BDD and Pt electrodes respectively. On
the other hand, they exhibit reversible redox behaviour in TEMAMS and irreversible nature in EMIN and
N2226TFSI media on the GC electrode. The phenolic compounds get oxidised at higher potential on the BDD
electrode followed by Pt and GC electrodes and their oxidation potential in the three media increases in
the order: TEMAMS < EMIN < N2226TFSI. Anodic polarisation studies in presence of phenols suggests that
the Pt and GC do not show any serious electrode fouling; however, the BDD gets deactivated severely,
as noted from the I4 pa/I1
pa values. Passivation of the BDD electrode in the EMIN medium containing the
2,6-DMP was investigated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM).
The effect of acetonitrile (CH3CN) on the activation of the BDD electrode surface was also studied in detai