Volume 5, Issue 1, January 2014

Indian Materials Congress® 

Ashutosh Tiwari

Advanced Materials Letters, 2014, Volume 5, Issue 1, Pages 1-1
DOI: 10.5185/amlett.2014.1001

We are pleased to announce Indian Materials Congress® (IMC). It will be an annual event organised by Vinoba Bhave Research Institute, India during 08-11 December each year from 2014. The goal of Congress is to provide a global platform for Indian researchers and engineers coming from academia and industry to present their research results and activities in the field of fundamental and interdisciplinary research of materials science.

Dtermination Of Critical Coagulation Concentration Of Silicon Nanoparticles

Jiangang Wei;Edward Khun

Advanced Materials Letters, 2014, Volume 5, Issue 1, Pages 2-5
DOI: 10.5185/amlett.2013.7523

This paper investigated the determination of critical coagulation concentration using a time-resolved dynamic light scattering technique. Silicon nanoparticles were used as model nanoparticles. Zeta potential of silicon nanoparticles were quantified using a zetasizer. The key results of this study show that critical coagulation concentration of silicon nanoparticles in NaCl is 0.2 M while critical coagulation concentration decreased to 0.01 for CaCl2 solution. This finding indicates that silicon nanoparticles are less stable in CaCl2 because of the more effective surface charge screening process occurred. This study provides information on the stability of nanoparticles in electrolyte solutions and may be served as reference in the risk assessment of nanoparticle spills into the natural aquatic systems.

Dissolution of Silver Nanoparticles In Presence of Natural Organic Matter

Zhang Linlin; Kulukawa Tanaka

Advanced Materials Letters, 2014, Volume 5, Issue 1, Pages 6-8
DOI: 10.5185/amlett.2013.7520

This study investigated the dissolution kinetics of silver nanoparticles in presence of natural organic matter. Silver nanoparticles were synthesized using chemical reduction method. Particle size and surface charges of the synthesized silver nanoparticles were characterized using a zetasizer. ICP-MS combined with ultrafiltration technology was used to quantify the silver nanoparticle dissolution in presence of natural organic matters. The obtained results suggested that the dissolution rate of silver nanoparticles decreases with increasing natural organic matter content. Our study provides important guidance in elucidating the transport and fate of silver nanoparticles in natural water conditions.

Temperature dependent raman spectroscopy of La1−xCaxMnO3 (x = 0.0 and 0.3) 

Khalid Sultan; M. Ikram;K. Asokan; Zubida Habib; Asima Jan; Sajad Ahmad Mir

Advanced Materials Letters, 2014, Volume 5, Issue 1, Pages 9-13
DOI: 10.5185/amlett.2013.6496

Temperature-dependent Raman spectroscopy of polycrystalline bulk samples of La1−xCaxMnO3 (x = 0.0, and 0.3) synthesized by solid-state reaction method is presented. As the temperature is decreased, there is significant change in intensity and full-width half maxima of all major Raman modes. This implies a structural rearrangement resulting in change of space group. This study brings out the variations in Raman spectra with temperature and also the effect of Ca doping on A-site in the compound LaMnO3. Possible effect of Laser heating on the samples has also been discussed.

Phenomenological analysis of the s-d exchange interaction in dilute Cu-Mn alloy at helium temperature

M.A. AL-Jalali

Advanced Materials Letters, 2014, Volume 5, Issue 1, Pages 14-16
DOI: 10.5185/amlett.2013.5486

The S-d exchange interactions in dilute Cu-Mn alloys was studied on concentration (C) varying between 10.5 and 2081.8 ppm of Mn in Cu within the (0.03K–4.2K) temperature range. Using electrical resistivity data on those alloys, the s-d exchange integral (Jsd), which is negative, has calculated to show a clear dependence on (Ln C). This dependence, confirming thus the dominance of Kondo effect below 1000 ppm impurity concentration, but above this concentration, we expected an interference between Kondo effect and spin glass regime, which mean that spin glass regime has to prevail more than Kondo effect.

Diastase α-amylase immobilization on sol-gel derived guar gum-gelatin-silica nanohybrid

Vandana Singh; Devendra Singh

Advanced Materials Letters, 2014, Volume 5, Issue 1, Pages 17-23
DOI: 10.5185/amlett.2013.7513

In the present communication, we report on diastase alpha amylase immobilization at guar gum-silica nanohybrid material (H5). The immobilized amylase (H5-Amyl) showed significantly higher bioactivity (21.62 U mg -1 ) as compared to free amylase (15.59 U mg -1 ) in solution at pH 5 and temperature 40°C. The kinetic parameters of the free (Km = 10.66 mg L -1 ; Vmax = 1.36 µmolemL -1 .min -1 ) and the immobilized enzyme (Km = 6.11 mg mL -1 ; Vmax = 1.45 µmolemL -1 .min -1 ) revealed that the immobilization has increased the overall catalytic property of the enzyme. The immobilized enzyme on recycling could show 87% of initial activity even in the sixth cycle. Since immobilization did not hamper the enzymatic reaction rate, the biocatalyst may be suitably exploited in food and pharmaceutical industries.

Novel biodegradable polymeric flocculants based on cationic polysaccharides  

R. P. Singh; Sagar Pal; Sk. A. Ali

Advanced Materials Letters, 2014, Volume 5, Issue 1, Pages 24-30
DOI: 10.5185/amlett.2013.6498

Novel flocculants for wastewater and industrial effluents treatment have been developed in authors’ laboratory based on modified polysaccharides. These flocculants have unique characteristics i.e. they are efficient with low dose usage like synthetic flocculants (e.g. polyacrylamide) and controlled biodegradable, shear resistant and inexpensive like polysaccharides. As contaminants have varying ionocity, various kinds of nonionic, anionic and cationic flocculants have been developed in authors’ laboratory. The recent approaches on the removal of toxic materials, removal of colour and reduction of total pollutant content from various wastewaters using modified polysaccharides is becoming more important in the present frontier research, because of their worst impact towards environment as well as human health. The present article deals with the recent developments which took place in authors’ laboratory on the synthesis of novel cationic flocculants based on modified polysaccharides derived from starch, amylose, amylopectin, chitosan, guar gum, glycogen, and tamarind kernel. The applications of these modified polysaccharides as flocculants for the treatment of various wastewaters including municipal sewage wastewater and as adsorbent for removal of reactive black dye from its aqueous solution have been discussed. The main objective of this article is to provide recent information about the most important features of these polymeric materials developed in authors’ laboratory and to show the advantages gained from the use of flocculants based on cationic polysaccharides in wastewater treatment.

Electrical properties of Ir/n-InGaN/Ti/Al Schottky barrier diode in a wide temperature range

R. Padma; V. Rajagopal Reddy

Advanced Materials Letters, 2014, Volume 5, Issue 1, Pages 31-38
DOI: 10.5185/amlett.2013.6503

The temperature dependent current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Ir/n-InGaN Schottky contacts have been investigated and analysed in the temperature range of 100-400 K. The estimated barrier heights and ideality factor of Ir/n-InGaN Schottky diode are 0.30 eV (I-V), 1.15 eV (C-V) and 3.05 at 100 K, and 0.94 eV (I-V), 0.97 eV (C-V) and 1.20 at 400 K respectively. The barrier height (Φb), ideality factor (n) and series resistance (RS) of Ir/n-InGaN Schottky diode are also evaluated using Cheung’s and Norde methods. Results show that the barrier heights (I-V) increase while ideality factor and series resistance decease with increasing temperature. Further, the discrepancy between Schottky barrier heights estimated from I-V and C-V measurements is also explained. It is observed that the interface state density Nss decreases with an increasing temperature. Experimental results showed that the conduction current is dominated by Poole-Frenkel emission in the temperature range from 100 K to 340 K and by Schottky emission above 340 K. The dominate conduction mechanism changed from Poole-Frenkel to Schottky emission in the temperature range from 340 K to 370 K. Finally, it is concluded that the temperature-dependent I–V characteristics of the Ir/n-InGaN Schottky diode can be successfully explained on the basis of thermionic emission (TE) mechanism.

Characterization of stiffened circumferentially cracked pipe with fiber reinforced polymer composite

Advanced Materials Letters, 2014, Volume 5, Issue 1, Pages 39-43
DOI: 10.5185/amlett.2013.7505

In this work the fiber reinforced polymer FRP patch is utilized to restore damaged metallic pipe with outer part through circumferential crack. A circumferential patch was employed to cover the full surface of the pipe at the cracked area. Linear elastic fracture mechanics LEFM scheme and finite element method ware used to evaluate the stress intensity factor (SIF) and the crack opening displacement (COD) as characterizing parameters along the surface crack profile. ANSYS package was utilized in this study and 3D-20 nodes solid element was adopted. Two loading conditions were investigated, that is, axial load and bending load. It was found that COD and hence the SIF reduced considerably in the vicinity of the crack tip using the stiffened technique.

Ring opening polymerization of lactide by using zinc prolinate catalyst 

Asutosh Kumar Pandey

Advanced Materials Letters, 2014, Volume 5, Issue 1, Pages 44-51
DOI: 10.5185/amlett.2013.6493

Zinc salts of L-proline, D-proline were used in homopolymerization of L, L-lactide and D, L-lactide. Linear PLA oligomer with Mn 2900-3400 Da, can be prepared with zinc (L-prolinate)2 catalyst. Less racemization were occurred in presence of Zn (L-prolinate)2 than Zn (D-prolinate)2. The catalyst structure of Zn (L-prolinate)2 and Zn (D-prolinate)2 remains intact after polymerization. The zinc is bioactive molecule so these polymers prepared by using this catalyst are bioabsorbable. The resulting polymers were characterized by infrared spectroscopy (IR), size exclusion chromatography (SEC), differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), 13 C NMR, 13 C Cross Polarization /Magic Angle Spinning ( 13 C CP/MAS) and MALDI ToF-MS.

Mixed influence of copper and some f-block elements on thermoluminescence intensity of CaSO4: Dy, P phosphors  

J. A. Wani; N. S. Dhoble; S. J. Dhoble

Advanced Materials Letters, 2014, Volume 5, Issue 1, Pages 52-58
DOI: 10.5185/amlett.2013.6488

Very little data on copper co-doped CaSO4: Dy and CaSO4: Dy, P phosphors seems to have been reported so far. In the present study the influence of copper and rare earths co-doping on thermoluminescence intensity of CaSO4: Dy, P phosphor has been investigated. Acid evaporation re-crystallization method was adopted for the synthesis purpose. Phosphors were characterized by scanning electron microscopy (SEM), photoluminescence (PL) and thermoluminescence (TL) techniques. Results obtained through this study are of mixed nature. In some cases, TL intensity is either greater or nearly equal to standard CaSO4: Dy while in other cases it is half or rather weak in comparison to standard CaSO4: Dy phosphor. Copper was found to suppress temperature peak structure above 300 o C. SEM micrographs of CaSO4: P, Dy, Cu, RE phosphors show that the particle size is in the micrometer range, 1 to 5 µm approximately. The systematic study carried out in this work is solely novel as no such report existed before. From this study it is clear now that by co-doping multi-impurities simultaneously to enhance TL characteristics of CaSO4: Dy phosphor is no longer useful because it proved otherwise.