Volume 3, Issue 4, September 2012

Guar Gum: A Versatile Industrial Plant Polymer

Hisatoshi Kobayashi

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 265-265
DOI: 10.5185/amlett.2012.9001

Guar gum is a non-ionic carbohydrate polymer derived from the endosperm of two annual leguminous plants Cyanaposis teragonalobus and Cyanaposis psoraloides. Chemically, it is galactomannan consisting straight chain of mannose units attached by β-D-(1→4) linkages, having α-D-galactopyranosyl unit bonded to poly(mannose) chain through (1→6) glycosidic links. Molecular weight of galactomannan varies ranging from 50 to 8000 kDa depending on the seeds and origin of plants; however polymer usually contains a definite ratio of building blocks, i.e., 1: 2 ratio of galactose to mannose. It is used in wide range of industries including cosmetics, paper, pharmacy, textile, adhesive, inks, lithography, paints, explosive and smoking products. In general, seed gums are non-toxic and applicable as emulsion stabilizer, thickening and gelling agents. Although, they nearly indigestible but consum in many food and pharmaceutical products as valuable additives to improve product qualities.

Theoretical Study Of The Geometric, Electronic Structure And Properties Of Alternating Donor-acceptor Conjugated Oligomers: Carbazole (Cbz)-based 3,4-ethylenedioxythiophene (Edot)

Z. El Malki; M. Haddad;M. Bouachrine; M. Hamidi; J-P Lere-Porte; F. Serein-Spirau; L. Bejjit

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 266-272
DOI: 10.5185/amlett.2011.8292

In this work the geometrical and electronic properties of (Carbazole-3.4-Ethylenedioxythiophene) (Cbz-Edot) based alternating donor-acceptor conjugated oligomers were studied by the density functional theory (DFT) at the B3LYP level with 6-31G(d) basis set. The acceptors investigated include thiazole (Z), thiadiazole (D), thienopyrazine (TP), thienothiadiazole (TD), benzothiadiazole (BT) and thiadiazolothienopyrazine (TPD). A low band gap will be expected in polymers containing donor-acceptor (D-A) repeating units. In order to predict the band gaps for guiding the synthesis of novel materials with low band gaps, we apply quantum-chemical techniques to calculate the band gaps in several oligomers. The results have been compared with those of thiophene and 3,4-ethylenedioxythiophene polymers with donor-acceptor fragment. The lowest excitation energies (Eex) and the maximal absorption wavelength (λabs) are studied using the time dependent density functional theory (TD-DFT), method. The electronic transitions of the absorption spectrum derived by TD-DFT method give useful structural and electronic information for designing novel conducting organic polymer materials. The theoretical results suggest that both the acceptor strength and the stable geometry contribute significantly to the electronic properties of alternating donor-acceptor conjugated copolymers.

Room Temperature Anodization Of Aluminum And The Effect Of The Electrochemical Cell In The Formation Of Porous Alumina Films From Acid And Alkaline Electrolytes 

Alaba O. Araoyinbo; Azmi Rahmat; Mohd Nazree Derman; Khairel Rafezi Ahmad

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 273-278
DOI: 10.5185/amlett.2012.2323

Nanoporous alumina was produced by anodic oxidation of aluminum in both acidic and alkaline electrolytes. Previous reports indicate that nanoporous alumina is mainly produced from strongly acidic electrolytes, and with the use of a low freezing temperature controlled bath to control the propagation and growth of the pores. We design an in-house electrochemical cell with an electronic circuit box attached, to control the anodization of aluminum at room temperature. The electrolytes used were phosphoric acid solution and sodium hydroxide solution. The pH of the acidic electrolyte was adjusted to 1, 3 and 5 with an applied potential of 50V and anodization time of 1 and 3 hrs, respectively, while the alkaline electrolyte pH was adjusted to 9, 11 and 13 with an applied potential of 40V and the templates anodized for 5 hrs. The micrographs of the nanoporous alumina formed from these electrolytes confirm that the nucleation and growth of nanoporous alumina films is achievable with the aid of the electronic circuit box connected to the electrochemical cell.  

Biocompatible Synthesis Of Silver And Gold Nanoparticles Using Leaf Extract Of Dalbergia Sissoo 

Chandan Singh; Ritesh K. Baboota; Pradeep Kr Naik; Harvinder Singh

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 279-285
DOI: 10.5185/amlett.2011.10312

This report presents a rapid, reproducible and a green biogenic approach for the biosynthesis of gold and silver nanoparticles using leaf extract of Dalbergia sissoo. The biomolecules present in the plant induced the reduction of Au 3+ and Ag + ions from HAuCl4 and AgNO3 respectively, which resulted in the formation of Dalbergia conjugated nanoparticles. The growth of nanoparticles was monitored by UV-vis spectrophotometer that demonstrated a peak at 545 and 425 nm corresponding to Plasmon absorbance of gold and silver nanoparticles respectively. The leaf extract was found to direct different shape and sized gold nanoparticles. Gold nanoparticles were 50-80 nm in size and their shape varied from spherical to few triangular and hexagonal polyshaped. While silver nanoparticle synthesized were spherical, in the range of 5-55 nm in size. X-ray diffraction studies corroborated that the biosynthesized nanoparticles were crystalline gold and silver. Fourier transform infra-red spectroscopy analysis revealed that biomolecules were involved in the synthesis and capping of silver nanoparticles and gold nanoparticles.

Structural, Dielectric And Conductivity Properties Of Ba2+ doped (Bi0.5Na0.5)TiO3 ceramic 

Meera Rawat; K. L. Yadav; Amit Kumar; Piyush Kumar Patel; Nidhi Adhlakha; Jyoti Rani

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 286-292
DOI: 10.5185/amlett.2012.2322

Polycrystalline (Bi0.5Na0.5)1-xBaxTiO3 [here after BNBT], x = 0, 0.02, 0.04, 0.06, 0.08, and 0.1 ceramics have been synthesized by conventional solid state reaction process and were characterized by X-ray diffraction technique, which indicates that on substitution of Ba 2+ in Bi0.5Na0.5TiO3 (BNT) ceramic there is splitting of the (2 0 0) peak for x ≥ 0.06. This splitting in the peak position reveals that the composition BNBT-0.06 is well in Morphotropic Phase Boundary (MPB) region where rhombohedral and tetragonal phase co-exist. Scanning electron micrograph shows decrease in grain size from 0.66 to 0.53 μm with increasing concentration of Ba 2+ ; and the dielectric constant of Ba 2+ doped BNT ceramics increased with decreasing grain sizes and a maximum value was attained at size of 0.54 ~ 0.56 μm. Doped BNT ceramic also exhibit diffuse phase transition and are characterised by a strong temperature and frequency dispersion of the permittivity which would be connected with the cation disorder in A-site of perovskite unit cell. Complex impedance spectroscopy is used to analyze the electrical behaviour of BNBT, which indicates the presence of grain effect and the composition exhibits Negative Temperature coefficient of resistance (NTCR) behaviour. The compounds exhibit Arrhenius type of electrical conductivity and the presence of non-Debye type of relaxation has been confirmed from impedance analysis.

Fabrication Of F-MCC-T Optical Fiber Nanoprobes By Pulling Method 

Shenqi Wang;Yi Ge

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 293-296
DOI: 10.5185/amlett.2011.4235

A nanoscale optical fiber probe with proper tailored tip diameter, taper angle and taper length is essential to monitor biological phenomena in single cells. In this work, F-MCC-T optical fiber, a multimode optical fiber with good propagating property within UV-Vis range is selected to fabricate the nanoprobe by pulling method. The method, particularly the factors affecting the tip diameter, taper angle and the taper length were thoroughly studied. Results show that optimal conditions could produce a nanoscale probe with a 50 nm of diameter, 6000 nm of taper length and taper angle of 28 degree with good reproducibility.

Optical And Electrical Properties Of Si Nanocrystals Embedded In SiC Matrix

Rimpy Shukla; C. Summonte; M. Canino; M. Allegrezza; M. Bellettato; A. Desalvo; D. Nobili; S. Mirabella; N. Sharma; M. Jangir; I.P. Jain

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 297-304
DOI: 10.5185/amlett.2012.5346

Silicon nanocrystals (Si NCs) embedded in a dielectric matrix showing tunable band gap properties have recently emerged as attracting top absorbers in silicon based high efficiency multijunction devices. This paper presents optical and electrical characterization of Si NCs in SiC matrix resulting from annealing at 1100°C of silicon-rich carbide (SRC)/SiC multilayers produced by Plasma Enhanced Chemical Vapour Deposition (PECVD), varying either the Si content in the SRC or the SiC thickness. Simulation of Reflectance and Transmittance spectra in the UV-Vis revealed that 1) the Si crystallization increases with increasing Si content; 2) a severe shrinkage of the multilayers occurs upon annealing due to the release of hydrogen and to crystallisation; 3) the growth of nanocrystals is affected by atomic environment and diffusivity of involved atoms at the investigated temperature. Temperature dependent conductivity measurements are performed on multlayers and on reference layers. The results show evidence of defect state conduction in the SiC matrix. 

Structural And Electrical Properties Of Ba3Sr2GdTi3V7O30 

B. B. Mohanty; M. P. K. Sahoo;R. N. P. Choudhary; P. S. Sahoo

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 305-308
DOI: 10.5185/amlett.2011.11317

The polycrystalline Ba3Sr2GdTi3V7O30 material of tungsten bronze structural family was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction analysis exhibits the formation of single-phase compound with orthorhombic crystal system. Surface micrograph recorded by scanning electron microscopic (SEM) technique has well defined but non-uniformly distributed grains throughout the surface of the pellet sample. Detailed studies of dielectric properties as a function of temperature (306-773 K) and frequencies (10 2 -10 6 Hz) suggest that the compound has frequency independent diffused dielectric anomaly at a temperature ~620 K which may be related to ferroelectric phase transition which is confirmed from polarization study. The frequency and temperature dependence of impedance property of the material were analyzed using a complex impedance spectroscopy. The Nyquist plots confirmed the presence of grain and grain boundary effect in the material.

Structure And Catalytic Activity Relationships Of Fe/Co Supported On Different Sources Of Al(OH)3 in The Production Of Multiwall Carbon Nanotubes By Catalytic Chemical Vapour Deposition Method 

H. Kathyayini;N. Nagaraju

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 309-314
DOI: 10.5185/amlett.2011.8291

Al(OH)3 from different sources has been used as supports for a mixture of Fe/Co salts and employed in the synthesis of Multiwall Carbon nanotubes by Catalytic Chemical Vapour Deposition method. These supported-catalysts have been characterized by Scanning Electron Microscopy, Powdered X-ray diffraction, and Thermo gravimetric studies. Surface area was determined by N2 adsorption technique. Carbon nanotubes synthesis reactions have been conducted at 700 o C using acetylene as the hydrocarbon source in N2 atmosphere. The quality and quantity of Multiwall carbon nanotubes depend not only on the carbon source, the textural & structural properties of the support and also their interactions with the active components available on the surface.

Structural And Impedance Spectroscopy Analysis Of Ba(Fe0.5Nb0.5)O3-BaTiO3 ceramic System 

N. K. Singh; Radheshyam Rai;Andrei L. Kholkin; Pritam Kumar

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 315-320
DOI: 10.5185/amlett.2012.5345

Polycrystalline samples of BaFe0.5Nb0.5O3 and (1-x)Ba(Fe0.5Nb0.5)O3-xBaTiO3, [referred as BFN and BFN-BT respectively] (x = 0.00, 0.15 and 0.20) have been synthesized by a high-temperature solid-state reaction technique. The formation of the compound was checked by an X-ray diffraction (XRD) technique. The microstructure analysis was done by scanning electron micrograph. The spectroscopic data presented in impedance plane show the grain and grain boundary contributions towards electrical processes in the form of semi-circular arcs. Detailed studies of dielectric and impedance properties of the materials in a wide range of frequency (100Hz–5MHz) and temperatures (30-282°C) showed that these properties are strongly temperature and frequency dependent.

Superconducting State Parameters Of Binary Metallic Glasses 

Aditya M. Vora

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 321-329
DOI: 10.5185/amlett.2012.4339

Well known Ashcroft’s empty core (EMC) model potential is used to study the theoretical investigation of the superconducting state parameters (SSP) viz. electron-phonon coupling strength, Coulomb pseudopotential, transition temperature, isotope effect exponent and effective interaction strength of some binary metallic glasses. More advanced screening function due to Farid et al. (F) has been employed to include the exchange and correlation effect on the aforesaid properties. The present results are found in qualitative agreement with other such earlier reported data available in the literature, which confirm the superconducting phase in the binary metallic glasses.

Solution Combustion Preparation Of Fe2O3- Nano-flakes: Synthesis And Characterization 

Pooja Dhiman; Amit Kumar;M. Singh

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 330-333
DOI: 10.5185/amlett.2012.4337

This paper outlines synthesis of iron oxide nano-flakes and their magnetic properties. Fe2O3–Nano-flakes were synthesized by simple, non-expensive solution combustion method using glycine as fuel. XRD confirmed the phase purity of the sample. Surface morphology and elemental composition were determined by SEM and EDX analysis. Mössbauer studies revealed the sextet at room temperature indicating ordered crystalline long range ferromagnetism. M-H measurements showed the saturated hysteresis curve with noticeable coercivity of 300 Oe. UV-vis spectra revealed the good optical absorbance in the visible region.

Spectroscopic Characterization Of Dichloro-DPQ With PMMA And PS Blended Films 

S. B. Raut; S. J. Dhoble;R. G. Atram

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 334-339
DOI: 10.5185/amlett.2012.4340

For the application in organic light-emitting diodes, the efficient new derivative of 2, 4-diphenyl quinoline i.e., 2(2’,4’-dichloro phenyl)-4-phenyl quinoline (dichloro-DPQ) has been synthesized by Friedlander condensation at 140°C. Blended films of dichloro-DPQ with poly (methyl methacrylate) (PMMA) and polystyrene (PS) at different weight % concentrations like 10, 5 and 1 wt% have been prepared. Structural and optical characterization techniques were used to characterize the crystalline powder. The photoluminescence in synthesized dichloro-DPQ polymeric compound shows emission peak in blue region at 462 nm in powder form and PL emission in dichloro-DPQ with PMMA and PS with different wt%; we get hypsochromic shift. Optical properties of dichloro-DPQ make it possible candidate material as blue organic phosphor for the field of light industry.

Synthesis Of CdSe Nanoparticles By Solvothermal Route: Structural, Optical And Spectroscopic Properties

Punita Srivastava;Kedar Singh

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 340-344
DOI: 10.5185/amlett.2012.5341

We have developed successfully the synthesis of highly yielded CdSe nanoparticles (NPs) at 60 0C by solvothermal route in which the cadmium and selenium precursors have been dissolved in deionized water, ethylene glycol and hydrazine hydrate. This route is very facile, inexpensive and less hazardous and ensures almost complete yield of the precursors. The powder product was well characterized by powder X- ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), UV-Vis spectroscopy, Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) .It is investigated that as synthesized powder has a hexagonal (Wurtzite) structure of CdSe with diameters of the particles are in the range of 10-15 nm. The formation mechanism is also discussed.

Comparative Investigation Of Cellular Response Of Nanoparticles

Sandeep Kumar; Neeraj Dilbaghi;Anju Manuja; Gaurav Bhanjana

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 345-349
DOI: 10.5185/amlett.2012.5342

Nanoparticles are being designed with chemically modifiable surfaces to attach a variety of molecules to improve biosensing, imaging techniques, delivery vehicles, and other useful biological tools. Keeping this in view, the present research work is focused on investigation of cytotoxicity of metal oxide nanoparticles. Different metal oxide nanoparticles (e.g titanium dioxide, zinc oxide, iron oxide, aluminum oxide etc) of different sizes and different concentrations were used to investigate the cellular response. Electron microscopy and colorimetric assays were used to characterize the various process steps. Zirconium oxide nanoparticles were used in suspension form stabilized with stabilizer and the others were used as their aqueous suspension. Results clearly reflect that as the concentration increases, cytotoxicity also increases. As aggregation occurs, cytotoxicity decreases. In suspension with stabilizer, cytotoxicity is more as compared to aqueous suspensions.

A Comparative Analysis Of Structural, Optical And Photocatalytic Properties Of ZnO And Ni Doped ZnO Nanospheres Prepared By Sol Gel Method

Shashi Kant;Amit Kumar

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 350-354
DOI: 10.5185/amlett.2012.5344

Zn1-xNixO (x=0, 0.5) nanoparticles were successfully prepared by sol gel method. Structural analysis was performed by XRD confirming phase purity and crystalline wurtzite structure. Surface morphology of nanosystems was performed by Scanning Electron Microscopy (SEM) and High Resolution Transmission Emission Microscopy (TEM) .Due to doping of ZnO nanoparticles the absorption shifted towards the visible region from UV region .The absorption increases on doping in the visible region.The Photocatalytic activity of both the doped and undoped ZnO was analysed via degradation of Methylene Blue. The Methylene Blue decomposition rate of pure ZnO and Nickel doped ZnO nanoparticles were studied under UV –Visible region. In the visible region both pure and doped ZnO decomposed Methylene Blue.This confirms the potential application of ZnO Nanoparticles for removal of harmful dyes from waste water and drinking water.The doping has a pronounced effect on the photocatalytic activity of nanoparticles. The degradation rate of the dye increased in case of Ni doped ZnO nanospheres.