Search

Coconut shell and wood apple shells are the two non-consumable (non-food/ protective)parts in the coconut and wood apple fruits. Immense availability of these shells in the Asian countries will produces the maximum amount of agro wastes. But these two shells have high potential due to their high strength and modulus properties. Coconut and wood apple shell powders exhibit praiseworthy characteristics as compared to other material powders such as low cost, environmental friendliness, renewability, high strength to weight ratio, low density and less abrasion to machine. As these shells are very much hard, they exhibit better strength when used in composites as additives. The components were made by mixing coconut shell powder, wood apple shell powder and epoxy resin at different and definite ratios and they were tested for mechanical properties. In the present work, fabrication of coconut, wood apple shell powder reinforced epoxy composites and experimental investigation of mechanical properties have been discussed. Six different percentages of coconut shell powder (0%, 3%, 6%, 9%, 12% and 15%) and wood apple powders (30%, 27%, 24%, 21% 18% and 15%) with epoxy resin are made to fabricate composites and results were analyzed. Obtained results indicates that, with 15% CNS and WAS have exhibited better tensile and compressive properties among all other combinations, composites with 3% CNS + 27% WAS powder reinforcements have shown better flexural properties and composites with 0% CNS+30% WAS powder have shown good results for impact strength tests.

NiFe films electrodeposited on Indium Tin Oxide (ITO) film coated on glass substrate. The NiFe films were electrodeposited at a current density of 19 mA/cm2. magnetoimpedance (MI) studies were carried out, it was observed that the MI values were increased from 2.8% to 120% and the MImax value shifted to lower frequency when thickness of the NiFe film increased. It clearly shows that thickness and conductivity of the substrate plays a significant role on MI values.A numerical-simulation conducted by Matlab, indicating the importance of the damping factor(α).

A comparative study of structure, stability and magnetic properties of Ni nanoparticles (NPs) synthesized by NaBH4 reduction method (SBR) and Polyol process (PP) has been carried out. Temperature and field dependence magnetization measurements suggest that 600 °C air annealed for 1 hour samples exhibit weak and strong magnetic properties for samples prepared by PP and SBR methods respectively. From the structural and magnetic measurements we conclude that Ni particles prepared by SBR and annealed at 600 °C air develops in to core-shell structure NPs while PP NPs under similar conditions show heterogeneous magnetic (Ni/NiO) behavior.

A comprehensive study of the structural and magnetic properties of Ni1-xCrx (x= 10, 20) nanocrystalline alloys prepared by mechanical milling are reported. From the structural and magnetic properties it is shown that the particles obtained after 30 hour milling are magnetically heterogeneous. High Curie temperature and weak magnetization values observed suggest that particles are in two phase structureor core shell structure.A comprehensive study of the structural and magnetic properties of Ni1-xCrx (x= 10, 20) nanocrystalline alloys prepared by mechanical milling are reported. From the structural and magnetic properties it is shown that the particles obtained after 30 hour milling are magnetically heterogeneous. High Curie temperature and weak magnetization values observed suggest that particles are in two phase structureor core shell structure.

Detailed magnetic, electrical, and thermal property measurements have been carried out on Ni100−xCrx binary alloys, mainly to study the effect of Cr. The following points emerge from this study: with the increase in Cr concentration, magnetic moment and Curie temperature linearly decreased and the ferromagnetic order is completely suppressed at the critical concentration (xcr ≈ 12.16 ± 0.03). The Rhodes–Wohlfarth ratio increases as the concentration approaches xcr, suggesting a weak itinerant ferromagnetic character of NiCr compositions (x

A systematic study on the formation and the stability of Al70Cu20Fe10 quasicrystalline alloy has been carried out through mechanical alloying. The influence of the milling parameters, sequence of additive elements, and heat treatment on the formation of icosahedral phase has been investigated through x-ray diffraction analysis and transmission electron microscopy. A combination of milling and heat treatment of Al70Cu20Fe10 composition resulted in the formation of a single icosahedral phase (i-phase) quasicrystal with face-centered structure. We present evidence that suggests the i phase is of a nanoquasicrystalline nature. From the present investigations, we propose an i-phase formation mechanism in Al–Cu–Fe system.

A detailed study of low temperature electrical transport properties of CoxGa100−x (x = 54, 55.5, 57) alloy has been carried out. The origin of the resistivity anomalies and correlation between magnetic and electrical transport properties are identified through an elaborate analysis. The weak localization and enhanced electron-electron interaction effects partially support the electrical transport properties of the system. Further, the observed magnetoresistance can be well represented by localized model along with quantum corrections. The low temperature magnetoresistance value near critical composition is comparable to that reported in giant magnetoresistance materials.

We investigated dc and ac susceptibilities of La1−xCaxMnO3 (x=0.2,0.3) single crystals. Obtained results show that La0.8Ca0.2MnO3 is clearly magnetically more frustrated than La0.7Ca0.3MnO3, indicating that charge/orbital fluctuation is enhanced in La0.8Ca0.2MnO3. A remarkable magnetic anomaly in the imaginary component of the ac susceptibility appears around 100 K for La0.8Ca0.2MnO3 to be attributed to the magnetic frustration arising from the strong competition between antiferromagnetic and ferromagnetic interactions that favor the existence of short-range charge/orbital ordering in this sample. In connection with the resistivity data, we propose that the order parameter of magnetic origin should be coupled to the other degrees of freedom in the case of La0.8Ca0.2MnO3 rather than La0.7Ca0.3MnO3.

The anisotropy between longitudinal and transverse magnetoresistance has been measured in a number of amorphous Fe90−xMnxZr10 (x=0–12) alloys in fields up to 50 kOe at various temperatures between 4.2 and 300 K. The observed composition dependence of the spontaneous resistivity anisotropy can straightforwardly be explained in terms of the two-current-conduction model. The composition dependence of spin-up and spin-down residual resistivity has been determined, and provides conclusive evidence of weak-itinerant ferromagnetism in the entire range of compositions of the present investigation. These observations are further supported by high-field susceptibility data obtained from magnetization measurements.

In the present work, magnetic and magnetoimpedance (MI) properties of (Fe70Co30)80B20−xSix (x = 0, 3, 5, and 10) amorphous ribbons in the frequency range of 500 kHz–13 MHz are reported. Our studies show that the thermal stability, magnetic behavior, and MI profiles have been strongly influenced by the Si content in amorphous ribbons. The magnetic isotherms show that all the samples of present study attain magnetic saturation values well below 500 Oe with coercivity values in the range of 0.2–0.09 Oe, which suggest ultrasoft nature of the samples. Interestingly, MI follows the magnetization variations with Si content. A maximum MI and field sensitivity of 46% and 4.3%, respectively, have been achieved for 10% B replacement by Si. The results show that the skin depth is strongly modified by the addition of Si, which in turn affects the impedance. The MI profiles show double peak and triple peak nature, which indicates the presence of transverse magnetic domain in all samples.

The magnetic and electrical transport properties of amorphous Fe‐Zr based alloys with compositions near 10 at. % Zr with various elements substituted for Fe are of particular interest. In the case of Mn substitutions the Curie temperature and the average magnetic moment decrease monotonically with increasing Mn content and the temperature dependence of the magnetization is significantly modified. The electrical transport properties of amorphous Fe90−xMnxZr10 (for x=0, 4, 8, and 12) over the temperature range of 4.2–300 K and the magnetoresistance for fields up to 4.0 T at 4.2 K are reported in the present work. A broad minimum in the resistivity is observed at around 255, 235, 200, and 180 K for the four compositions, respectively. In the case of the x=8 sample a second minimum occurs at around 50 K. The magnetoresistance of all samples shows a sharp increase for small fields and a linear field relationship for fields above about 0.1 T.

We report magnetic and magnetoimpedance (MI) properties of as-quenched and Joule annealed (with and without external magnetic field) amorphous Co73Fe4.5Ni0.5Mn0.5Nb0.5Si4.2B16.8 alloy composition. The Joule annealing in the presence of magnetic field induces not only surface microstructural changes but also favourable anisotropy. Dc magnetic measurements show controlled annealing enhances soft magnetic nature of the sample. Virgin ribbons show MS ∼ 125 emu/g with μr ∼ 104 and exhibit large MI ratio of ∼100% at 3 MHz frequency. This MI ratio was further enhanced to 152% on Joule annealing (current density 0.85 × 107 A/m2) in the presence of applied magnetic field of 500 Oe. The field dependence MI shows a double-peak feature in as-spun ribbons, which is significantly enhanced for field annealed (FA) samples. The enhancement in MI and magnetic field sensitivity (η) in FA amorphous ribbons is attributed to the development of nanograins on the surface layer that strengthens the transverse magnetic structure.

Magnetic thin films of NiFe and CoNiFe were electrodeposited from three different deposition baths on copper wires of 100 μm diameter. The magnetic and magneto-impedance (MI) properties of the samples were investigated as a function of saccharin additive concentration in the plating bath. For all intermediate frequencies, the MI ratio increased with saccharin concentration in the plating bath up to a critical concentration and then saturates. The change in MI with saccharin concentration in electrodeposition bath was attributed to the grain size reducing action of saccharin which in turn reduces the coercivity of the film, making it soft magnetic. The origin of MI lies in the combined effect of domain wall motion and spin rotation which contributes to permeability. Inductance spectroscopy was used to evaluate the magnetic characteristic of the samples by modeling magnetic film-coated wires in terms of equivalent electrical circuit; namely parallel inductance and resistance circuit in series with series A circuit. The domain wall motion was found to be greatly affected by saccharin addition to the bath, which was revealed through the study of variations in these circuit parameters. The domain wall motion thereby affects the magnetic softness of samples, which is reflected by MI enhancement.

We study the responses of a cultured neural network when it is exposed to epileptogenesis glutamate injury causing epilepsy and subsequent treatment with phenobarbital by constructing connectivity map of neurons using correlation matrix. This study is particularly useful in understanding the pharmaceutical drug induced changes in the neuronal network properties with insights into changes at the systems biology level. (C) 2010 American Institute of Physics. [doi:10.1063/1.3398025]

The Ni:B2O3 nanoparticles have been synthesized by a novel two-step chemical reduction method, under ambient conditions and subsequent annealing in air. The evolution of this structure has been followed through a sequence of annealing treatments. Structural and magnetic investigations on as-prepared and annealed samples revealed that as-prepared samples are weakly magnetic and develop into spherical ferromagnetic entities with superior magnetic properties. The saturation magnetization (Ms∼42 emu/g) and coercivity (Hc∼482 Oe) at room temperature clearly suggest that the air annealed (500 °C) samples are protected from the oxidation due to formation of B2O3 protective layer. The magnetization results are consistent with the observed microstructural changes and satisfactorily explained on the basis of a core-shell model, where we consider each particle as a magnetically heterogeneous system consisting of a ferromagnetic core of Ni and nonmagnetic shell of B2O3. These results suggest that this kind of nanocom...