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CONTENTS
Volume 3, Number 4, December 2014
 

Abstract
Copolymers of gelatin and poly (vinyl alcohol), (PVA) grafted by acrylic acid (AAc) with excellent water absorption and retention abilities under neutral conditions were successfully synthesized using 60Co gamma radiations in presence of ammonium persulphate (APS), as water soluble initiator and sodium bicarbonate (NaHCO3) as foaming agent. The optimum synthesis conditions pertaining to maximum swelling percentage were evaluated as a function of gelatin/PVA ratio, amount of water, concentration of APS, NaHCO3, monomer concentration and total irradiation dose. Maximum percent swelling (1694.59%) of the copolymer, gelatin-co-PVA, was obtained at optimum [APS] = 2.92x10-1 mol/L, [NaHCO3] = 7.94x10-2 mol/L and 1.5 mL of water at total dose of 31.104 kGy while in case of grafted copolymer, (gelatin-co-PVA)-g-poly(AAc), maximum percent swelling (560.86%) was obtained using 8.014x10-1 mol/ L of AAc in 9 mL water with 31.104 kGy preirradiation dose. The pristine and grafted copolymers were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning electron Microscopy (SEM), Thermal gravimetric analysis (TGA) and X-Ray Diffraction (XRD) methods. The copolymers loaded with an antiseptic, Povidone, were used as wound dressing materials for wounded gastrocnemius muscle of mice and the results exhibit that (gelatin-co-PVA)-g-poly (AAc) copolymer is a potent wound dressing material as compared to the copolymer.

Key Words
PVA; gelatin; acrylic acid; gamma ray irradiation; APS, sodium bicarbonate

Address
Inderjeet Kaur and Pooja Bhati: Department of Chemistry, Himachal Pradesh University Summer Hill, Shimla, India, 171 005

Sushma Sharma: Department of Bio sciences, Himachal Pradesh University Summer Hill, Shimla, India, 171005

Abstract
Noble metal nanoparticles (mainly Au, Ag, Pt and Pd) have received enormous attention owing to their unique and fascinating properties. In the past decades, many researchers have reported methods to control the shape and the size of these noble metal nanoparticles. They have consequently demonstrated outstanding and tunable properties and thus enabled a variety of applications such as surface plasmonics, photonics, diagnostics, sensing, energy storage and catalysis. This paper focuses on the recent advances in the solution-phase synthesis of shape- and size-controlled noble metal nanoparticles. The strategies and protocols for the synthesis of the noble metal nanoparticles are introduced with discussion of growth mechanisms and important parameters, to present the general criteria needed for producing desirable shapes and sizes. This paper reviews their remarkable properties as well as their shape- and size- dependence providing insights on the manipulation of shape and size of metal nanoparticles, necessary for appropriate applications. Finally, several applications using the shape- and size-controlled noble metal nanoparticles are highlighted.

Key Words
metal nanoparticles; size and shape; growth mechanism; properties; applications

Address
Kyeong Woo Choi, Seong Ji Ye, and O Ok Park: Department of Chemical and Biomolecular Engineering (BK21+ graduate program), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehakro, Yuseong-gu, Daejeon 305-701, Republic of Korea

Do Youb Kim: Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT),
141 Gajeongro, Yuseong-gu, Daejeon 305-600, Republic of Korea

Abstract
In this study, a forging steel alloyed with both Nb and V was used as experimental material and the hot deformation behavior has been studied for this steel by conducting the compressive deformation test at temperature of 900-1150s-1s-1 in a MMS-300 thermo-mechanical simulator. The microstructure evolution, particularly the dynamically recrystallized microstructure, of the experimental steel at elevated temperatures, strain rates and strain levels, was characterized by optical microstructural observation and the constitutive equation in association with the activation energy and Zener-Hollomon parameter. The curves of strain hardening rate versus stress were used to determine the critical strain and peak strain, and their relation was connected with Zener-Hollomon parameter. Under the conditions of processing temperature 900 ocand strain rate 0.01 s-1, the dynamic recrystallization took place and the austenite grain size was refined from 164.5 µm to 28.9 µm.

Key Words
Nb-V microalloyed forging steel; dynamic recrystallization; microstructure evolution; constitutive equation; activation energy

Address
Yang Zhao: School of Materials and Metallurgy, Northeastern University, Shenyang 110819, China

Liqing Chen: State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China

Xianghua Liu: Research Institute of Science and Technology, Northeastern University, Shenyang 110819, China

Abstract
Ce4+, Eu3+, Tb3+ co-doped Ca3Si3O8F2 phosphor was synthesized via solid state reaction method using CaF2, CaCO3 and SiO2 as raw materials for the host and Eu2O3, CeO2, and Tb4O7 as activators. The luminescent properties of the phosphor was analysed by spectrofluorophotometer at room temperature. The effect of excitation wavelengths on the luminescent properties of the phosphor i.e. under near-ultraviolet (nUV) and visible excitations was investigated. The emission peaks of Ce4+, Eu3+, Tb3+ co-doped Ca3Si3O8F2 phosphor lays at 480(blue band), 550(green band) and 611nm (red band) under 380nm excitation wavelength, attributed to the Ce4+ ion, Tb3+ ion and Eu3+ ions respectively. The results reveal that the phosphor emits white light upon nUV (380nm) / visible (465nm) illumination, and a red light upon 395nm / 535nm illumination. RE ions doped Ca3Si3O8F2 is a promising white light phosphor for LEDs. The emission colours can be seen using Commission international de l

Key Words
luminescence; phosphor; solid state reaction; raw materials; activators; LED

Address
K.Suresh: Department of Physics, CSR Sarma College, Ongole -523 001, A.P., India

Nannapaneni V.PoornachandraRao: Department of Physics, Rajiv Gandhi University of Knowledge Technologies,
IIIT, Basara-504101, AP, India

K.V.R.Murthy: Department of Applied Physics, Faculty of Engineering and Technology,
M.S. University of Baroda, Vadodara-390 001, India

Abstract
Magnetic and conducting aniline sulfide resin cross-linked (ASC-Fe3O4) nanocomposite has been prepared in the presence of aniline sulfide resin (ASR), aniline, Fe3O4 coated by polyethylene glycol (PEG) and initiator. The magnetic properties of the resulting composites showed ferromagnetic behavior, such as high-saturated magnetization (Ms= 41 emu/g), and coercive force (Hc=1.5 Oe). The saturated magnetization was increased by increasing of Fe3O4 content and decreased by increasing aniline ratio. The transmission electron micrograph (TEM) and X-ray diffraction proved that nanometer-sized about 20-30 nm Fe3O4 in the composite. The average size of ASC-Fe3O4 nanocomposite with core-shell structure was about 50-60 nm, and polydisperse. This approach may also be extended to the synthesis and modification of other polymers. Electrical conductivity of aniline sulfide resin cross-linked (ASC) nanocomposite has been studied by four-point probe method and produced 3.3

Key Words
aniline-sulfide resin; magnetic; conducting polymer; nanocomposite

Address
Seyed Hossein Hosseini: Department of Chemistry, Faculty of Science, Islamic Azad University, Islamshahr Branch, Tehran-Iran


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