Volume 7, Issue 5, May 2016

Special Issue In Celebration Of Prof. Ingemar Lundström’s 75th Birthday

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 337-338
DOI: 10.5185/amlett.2016.5001

It is our great pleasure to publish the 7 th volume, 5 th issue, May 2016 of Advanced Materials Letters in the celebration of 75 th birthday’s Prof. Ingemar Lundström. Prof. Lundström was born on 9 th May 1941 in Skellefteå ("Gold Town", Västerbotten County), Sweden. He graduated in Electrical engineering from Chalmers University of Technology, Gothenburg, Sweden. In 1970, he received his PhD in Solid state electronics at the Chalmers University of Technology, Gothenburg. He is a Professor in applied physics in Linköping University since 1978. 

Influence Of Hollow Silica-alumina Composite Spheres Prepared Using Various Amount Of L(+)-arginine on Their Activity For Hydrolytic Dehydrogenation Of Ammonia Borane

Naoki Toyama; Haruki Inoue; Shinobu Ohki; Masataka Tansho; Tadashi Shimizu; Tetsuo Umegaki; Yoshiyuki Kojima

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 339-343
DOI: 10.5185/amlett.2016.6072

In this work, we investigate influence of amount of L(+)-arginine on morphology of hollow silica-alumina composite spheres and their activity for hydrolytic dehydrogenation of ammonia borane. Hollow silica-alumina composite spheres were prepared by polystyrene templates method. In this method, silica-alumina composite shell were coated on polystyrene particles via a sol-gel reaction using L(+)-arginine as promoter, and the polystyrene template particles were removed by calcination. From the result of transmission electron microscopy, shell thickness of the hollow spheres prepared amount of L(+)-arginine of 0.0581, 0.1163, 0.2325, and 0.4650 g were 10, 20, 26, and 30 nm, respectively. From the result of nitrogen sorption, average pore size of the hollow spheres prepared amount of L(+)-arginine of 0.0581, 0.1163, 0.2325, and 0.4650 g was 6.2, 4.2, 3.4, and 2.9 nm, respectively. These results indicate that pore size and shell thickness changed into adjusting amount of L(+)-arginine. Activity of the hollow spheres prepared using various amount of L(+)-arginine for hydrolytic dehydrogenation of ammonia borane were compared. The result indicates that amount of hydrogen evolution of all the hollow spheres was almost the same level. On the other hands, hydrogen evolution rate increase with decrease of amount of L(+)-arginine. 

A First-principle Study Of The Optical Properties Of Pure And Doped LaNiO3

Tarun Kumar Kundu; Debolina Misra

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 344-348
DOI: 10.5185/amlett.2016.6105

Density Functional Theory (DFT) is employed to study the various optical properties of pseudo-cubic LaNiO3. As LaNiO3 is a strongly correlated material, conventional DFT like LDA or GGA and even GW approximation fail to describe, we have examined the optical spectra of this compound using GGA(PBE)+U approach. The advantage of incorporating Hubbard U in this approach is to take the strong electronic correlation in the system into account. The optical spectra of this compound are found to be consisted of the Drude peak and some high energy peaks. While the Drude peak reflects the dominant free carrier contributions at the low energy region, the high energy peaks originate from the inter-band transitions within the system. We have also studied the remarkable changes in the optical properties in Fe doped LaNiO3 (LaNi1-xFexO3), in order to probe related properties, corresponding to their applications in solid-oxide fuel cells. Our calculations have revealed that even 25% of Fe doping is adequate to trigger a first order metal to insulator transition in LaNiO3. The optical spectra of LaNi1-xFexO3 compounds are calculated using the hybrid functional HSE and the doping-induced metal to insulator transition in LaNiO3 is attributed to the altered crystal environment and electronic configuration of the compound. 

Tunneling Effect Of Photon-assisted AZO/SiOx/n-Si Heterojunction Device At Reverse Bias

H. W. Du; J. Yang; F. Xu; L. Zhao; Z. Q. Ma

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 349-352
DOI: 10.5185/amlett.2016.6169

Physical asymmetrical Metal / AZO / SiOx / n-Si / Metal devices in semiconductor-insulator-semiconductor (A-SIS) framework were investigated for their anormaly current-voltage characteristics under light irradiation. The devices showed a normal rectifying character in dark but manifested a peculiar current-voltage feature at reverse bias under illumination. Considering the change of energy band structure at the reverse electric field, it was found that the transport of electrons was mainly dominated by the thermionic emission and quantum tunneling at low voltage. With the increase of the reverse bias, the electrons were able to tunnel through the reduced barrier of ultra-thin SiOx layer (<1nm) and an effective triangle-like barrier of silicon. An appropriate simulation of the J-V relationship demonstrated that the photons acting as the assisted part magnified the reverse current density, and the thickness of SiOx layer managed the amount of the reverse saturation current. 

Percolation Phenomena In Polymer Nanocomposites

Moises Oviedo Mendoza; Edna M. Valenzuela-Acosta; Evgen Prokhorov; Gabriel Luna-Barcenas; Siva Kumar-Krishnan

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 353-359
DOI: 10.5185/amlett.2016.6091

In this work, we report the relationship between the electrical conductivity and nanoparticle effective surface area with functional properties of polymer-metal and polymer-clay nanocomposites. Conductivity of the nanocomposite strongly depends upon metal/clay nanoparticle size and concentration that ultimately dictate where the system percolates. Knowledge of percolation properties allows the design of functional nanocomposites for biomedical and sensors applications. Herein we report the successful production of three functional chitosan-metal/clay nanocomposites: a) chitosan-Ag films with antibacterial properties, b) chitosan-Au potentiometric sensor for detection of Cu ++ and c) chitosan-nanoclay potentiometric sensor for detection of NO3-. For all these applications the best functional performance of nanocomposites has been observed when NPs concentration increases and approaches the percolation threshold. The obtained relationship between electrical percolation threshold and functional properties of polymer nanocomposites is of primary importance in the design of high-performance applications.

Designing Of LDPE/fly Ash/ Expanded Graphite Sheet For Electrostatic Charge Dissipation Application

Anuj Gulati; Narayan Agarwal;Sundeep K. Dhawan; Swati Varshney

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 360-365
DOI: 10.5185/amlett.2016.5841

The paper aims to explore the utilization of industrial waste fly ash as a filler material into low density polyethylene (LDPE) polymer matrix with / without expanded graphite to optimize the electrostatic charge dissipative (ESD) properties as injection molded sheets. Homogeneous mixing of composite mixture has been carried out in a single screw extruder via melt blending and designed to sheet form by using an injection molding machine. The mechanical and thermal properties of the composite sheet depend on the formulation of composite material. The presence of fly ash particles and fly ash/ expanded graphite in the polymer system allows the composite sheet to acquire good mechanical and electrostatic charge dissipative properties. Static voltage decay rate and decay value measurement were carried out for LDPE and LDPE/fly ash/expanded graphite composite sheet. LDPE/fly ash/expanded graphite composite sheet having high percentage of expanded graphite showed good electrostatic charge dissipative properties. Further, structural analysis, surface morphology, thermal stability and mechanical properties have been explored by XRD, SEM, TGA and tensile testing. 

Tumor-targeting Hederagenin-loaded Magnetic Nanoparticles For Anti-cancer Drug Delivery

Kwon-Jai Lee; Jeung Hee An; Jae-Soo Shin; Dong-Hee Kim; Kang-Hyun Chung

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 366-370
DOI: 10.5185/amlett.2016.6134

In this study, the anti-tumor activity of hederagenin-loaded magnetic nanoparticles (HMP) was examined in cancer cells. Composite nanoparticles with an average size of 32.5 nm were prepared using a chemical co-precipitation technique. The characteristics of the particles were determined via X-ray diffraction, field emission scanning electron microscopy, attenuated total reflectance fourier transform-infrared spectroscopy, and energy-dispersive X-ray spectroscopy. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that the magnetic nanoparticles were non-toxic against cancer. In particular, HMPs were cytotoxic at 73.12 % breast cancer (MCF-7), at 70.2 % against prostate cancer (DU145 cells), at  72.15 % against neuroblastoma cancer cells (U87), at 579.15 % in human brain cancer cells (SH-SY5Y), and at 74.5 % in human cervical cancer cells (HeLa) at 250 mg/mL. Our results demonstrated the biological applicability of HMPs as anticancer agents and as agents for enhanced drug delivery against human prostate cancer cells. Our results indicate that the magnetic nanoparticles were biostable and that HMPs functioned effectively as drug delivery vehicles. 

Optical Modes Of Vibration In A Metamaterial Slab Including Effects Of Retardation

G. Becerra O; J. C. Granada E

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 371-375
DOI: 10.5185/amlett.2016.6111

The frequencies of optical modes of vibration in a metamaterial slab, contacting with vacuum, are investigated when the slab dielectric permittivity and the magnetic permeability show resonant behavior. Retardation effects are included in the no radiative zone. On the basis of the linear response theory, we calculate the components of the electromagnetic Green propagator. The dispersion curves and the corresponding power spectra are determined from the poles and the imaginary part of these components. Two sets of surface polaritonic frequencies are found for transversal electric TE- and transversal magnetic TM surface modes, corresponding to bonding and antibonding oscillations of the electric and magnetic fields at the slab surfaces. It is shown that for all the range of values in the relation between the resonance frequency of magnetic permeability and the resonance frequency of the dielectric permittivity there is one TE and one TM backward mode with negative group velocities. This parameter relation determines if the frequency range of TM modes can be separated from the corresponding interval for TE modes. Present work can be extended to consider waves in photonic crystals containing anisotropic slabs with resonant behavior in the optical properties, which can be useful to design omnidirectional optical filters. 

Cerium(IV) Oxidations Of Sulfated Polysaccharides In Aqueous Perchlorate Solutions: A Kinetic And Mechanistic Approach

Ahmed Fawzy; Refat M. Hassan; Ismail Althagafi; Moataz Morad

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 376-382
DOI: 10.5185/amlett.2016.6327

The kinetics of oxidation of iota- and lambda-carrageenans as sulfated polysaccharides by cerium(IV) was studied spectrophotometrically in aqueous perchlorate solutions at a fixed ionic strength of 2.0 mol dm -3 and a temperature of 25 o C. The reactions showed a first order dependence on [Ce IV ], whereas the orders with respect to each carrageenan concentration were less than unity. The reactions exhibited fractional-first order kinetics with respect to [H + ]. Increasing ionic strength increased the oxidation rates. The oxidation products of carrageenans were characterized by elemental analysis and IR spectra as their diketo-acid derivatives. The oxidation products were found to have high tendencies to form coordination polymer complexes with some metal cations such as Ba II , Cd II , Pb II and Ag I . Kinetic evidences for the formation of 1:1 complexes were revealed. Plausible mechanistic scheme for cerium(IV) oxidations of carrageenans were proposed. The activation parameters with respect to the slow step of the reactions were evaluated and discussed. The rate laws have been derived and the reaction constants involved in the different steps of the mechanisms were calculated. The activation parameters associated with the rate-determining step of the mechanism along with thermodynamic quantities of the equilibrium constants were computed and discussed. 

Biosynthesis Of Silver Nanoparticles Using Convolvulus Pluricaulis Leaf Extract And Assessment Of Their Catalytic, Electrocatalytic And Phenol Remediation Properties

Shadakshari Sandeep; Arehalli S. Santhosh; Ningappa Kumara Swamy; Gurukar S. Suresh; Jose S. Melo; Puttaswamappa Mallu

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 383-389
DOI: 10.5185/amlett.2016.6067

In the present work, we report on the biosynthesis of silver nanoparticles (AgNPs) using leaf extract of Convolvulus pluricaulis (Shankapushpi, bindweed) at room temperature. Synthesis of AgNPs is carried out by incubating the leaf extract in presence of AgNO3. Formation of AgNPs is confirmed by the appearance of a prominent surface plasmon resonance band in the UV-visible spectrum at 420 nm. The biosynthesized AgNPs are characterized by powder X-ray diffraction (XRD) studies, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo gravimetric analysis (TGA) and differential thermo gravimetric (DTG) analysis. Further, the biosynthesized AgNPs are investigated for their catalytic, electrocatalytic and phenol remediation properties. The investigations revealed that the biosynthesized AgNPs excel in their respective applications. Based on the results, present study concludes that AgNPs can be biosynthesized using leaf extract of Convolvulus pluricaulis and further can be employed for applications in electrochemical sensing, dye degradation and phenol remediation. 

Rapid Homogenization Method For Synthesis Of Core/shell ZnO/CdS Nanoparticles And Their Photocatalytic Evaluation

Suraksha Rasal; Sunita Jadhav;Pawan K. Khanna; Priyesh V. More; Chaitanya Hiragond

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 390-397
DOI: 10.5185/amlett.2016.6334

ZnO/CdS core-shell hetero nanostructures with different shell thickness have been successfully developed by a solution chemistry method employing rapid homogenization concept. The obtained core/shell nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), FTIR, Raman, photoluminescence (PL), and UV-visible spectroscopy. All analytical and spectroscopic tools supported the formation of CdS shell over ZnO core. ZnO/CdS core-shell nanostructures were evaluated for their photocatalytic activity against methylene blue (MB), a common industrial water pollutant. It was observed that the ZnO/CdS core-shell nanostructures can effectively function as a photocatalyst under both UV and sunlight for degradation of MB. It was also observed that the degradation of MB was higher from core/shell nanostructures than the physical mixture of ZnO-CdS which was prepared separately.

Contact Angle Measurement Studies On Porous Anodic Alumina Membranes Prepared Using Different Electrolytes

P. Ramana Reddy; Ajith K. M.;N. K. Udayashankar

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 398-401
DOI: 10.5185/amlett.2016.6230

This paper investigates the effect of pore widening duration on the wetting properties of nanostructured porous anodic alumina (PAA) membranes fabricated using sulphuric and oxalic acid as electrolytes by two step anodization process. XRD analysis shows that prepared PAA membranes were amorphous in nature. With increasing of pore widening durations from 0 to 120 min, the contact angle of PAA membranes varied from 21 to 78Ëš. It was noticed that PAA membranes were hydrophilic in nature in the present of water medium. In the presence of acetone medium, PAA membranes prepared with 1hr pore widening time showed super hydrophilic behaviour. 

Low Cost Biosorbents Based On Modified Starch Iron Oxide Nanocomposites For Selective Removal Of Some Heavy Metals From Aqueous Solutions

Abdul-Raheim M. Abdul-Raheim; El-Saeed Shimaa M.; Farag Reem K.; Abdel-Raouf Manar E

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 402-409
DOI: 10.5185/amlett.2016.6061

In this work, the starch extracted from potato peels was modified with acrylic acid. Nanoparticles composed of modified starch polymer and Fe3O4 (modified potato starch-magnetic nanoparticles, MPS-MNPs) were synthesized. The prepared nanoadsorbents were used for selective exclusion of Pb 2+ , Cu 2+ , and Ni 2+ ions from water. They were characterized by different analytical instruments such as FTIR, TEM and XRD. Adsorption of all captured metal ions onto MPS-MNPs was observed to be reliant on temperature, pH and contact time. Clump adsorption balance was come to in 60 min and most extreme uptakes for Cu 2+ , Pb 2+ and Ni 2+ in non-aggressive adsorption mode were 100, 70 and 100 mgg −1 , respectively at 35 â—¦C. In focused adsorption tests, PS-MNPs specially adsorbed Ni 2+ ions with an affinity order of Ni 2+ >Cu 2+ >Pb 2+ . The effect of monomer and initiator concentrations on grafting process was studied. Furthermore, the recyclability of PS-MNPs was investigated. 

Structural, Morphological, Optical And Electrical Properties Of PbSe Thin Films Grown By Chemical Bath Deposition

Suresh Sagadevan; Jiban Podder;Isha Das

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 410-413
DOI: 10.5185/amlett.2016.5949

Lead selenide (PbSe) thin films were processed by chemical bath deposition (CBD) technique. To analyze the structure and the crystallite size of PbSe thin film X-ray diffraction (XRD) analysis was used. Using Scanning Electron Microscopy (SEM) the surface examination of the film was conducted. With the help of UV-visible absorption spectrum investigation of the optical properties were held. All the optical constants were determined from UV-visible absorption spectrum. The dielectric examination of PbSe thin films were analyzed for various frequencies and various temperatures. The AC electrical conductivity analysis brought to light that the conduction depended on both the frequency and the temperature. Photoconductivity analysis was carried out to the PbSe thin films. 

Charge Carrier Generation In A Polymer By Using N-type Doping For The Improvement Of Electrical Properties

Manisha Bajpai; R. S.Tiwari;Suresh Chand; Ritu Srivastava; Ravindra Dhar

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 414-418
DOI: 10.5185/amlett.2016.6028

In this paper, the charge carrier generation in polymer blends by chemical doping has studied. In these studies, we employed n-type dopant molecule decamethylcobaltocene (DMC) which exhibit very strong electron donating nature. We have demonstrated that such type of doping favours the formation of charge transfer complex (CTC) and reduce the recombination probability. We have confirmed the CTC formation form the absorption spectroscopy. Further we have used transient photoluminescence spectroscopy to reveal the reduced initial recombination of charge transfer exciton. We interpret our results based on a reduced formation of emissive charge transfer excitons in doped blends, induced by state filling of immobile tail states in the polymer HOMO.