International Journal of Nano and Biomaterials (27 papers in press)
Collagen/Chitosan Hybrid 3D-Scaffolds as Potential Biomaterials for Tissue Engineering
by Hilary Urena-Saborio, Emilia Alfaro-Viquez, Daniel Esquivel-Alvarado, Marianelly Esquivel, Sergio Madrigal-Carballo
Abstract: Chitosan (CHT) has been reported to be biocompatible, bio-absorbable and particularly, is considered a good wound-healing accelerator. On the other hand, collagen (CGN) is one of the most widely used matrix biomaterial in tissue engineering. Highly porous CGN single 3D-scaffolds have been used to support in vitro growth of many types of tissues. We fabricated hybrid 3D-scaffold biomaterials by mixing CHT from native shrimp waste streams and CGN from tilapia aquaculture waste by-products, applying previously developed methodologies involving solvent casting and freeze-drying. CGN/CHT hybrid 3D-scaffolds were characterized according to its water uptake capacity, mechanical properties, thermal behavior (TGA), and morphology (SEM). Hybrid 3D-scaffolds showed improved stability, greater porosity, increased thermal stability, and mechanical properties, as well higher biodegradation as compared to single 3D-scaffolds. Cell culture incubation with adipose tissue-derived stem cell (ADSC) and SEM imaging showed that CGN/CHT hybrid 3D-scaffolds allowed ADSC adhering, spreading, and growing in vitro.
Keywords: Collagen; chitosan; scaffolds; tissue engineering.
Effect of Annealing Temperature On Super capacitive Behavior Of Hydrothermally Synthesized ZnO Nano-platelets
by Arya Das
Abstract: Tungsten trioxide (WO3) thin films have considerable interest due to its wide variety of properties, and extensively studied for various applications such as chromogenic devices, switching mirrors, optoelectronic devices and gas sensors. In this view, our present investigations are aimed at electron beam evaporated thin films of WO3. The films were deposited at an oxygen partial pressure of 2x10-4 mbar and at different substrate temperatures ranging from room temperature (RT) to 4500C. The films were annealed at 4000C about 2 hours and the properties were studied systematically. The X-ray Diffraction studies show the diffraction peak of (320) at 2θ = 44.070 which indicate the Orthorhombic phase of WO3 and also the other peaks represent the hexagonal phase of WO3. Due to annealing of the films, the monoclinic phase is also observed. The surface morphology of WO3 thin films was investigated by using Atomic Force Microscopy and Scanning Electron Microscopy, which supports the above data. The Energy Dispersive X-ray (EDX) compositional analysis confirmed the presence of W and O. The optical properties were studied by UV-VIS Spectrophotometry and hence the bandgap values are calculated.
Keywords: Tungsten trioxide thin films; annealed; structural; morphological; optical and compositional.
Effect of Gamma Irradiation on Electrical and Magnetic Properties of Bismuth Doped Cobalt Ferrite Nanoparticles
by KRUTIKA ROUTRAY, DIRTHA SANYAL, Pratip Kumar Mukhopadhyay, DHRUBANANDA BEHERA
Abstract: Bismuth doped Cobalt ferrite nanoparticles has been prepared by sol-gel auto combustion method. An attempt has been made to study the electrical and magnetic transport properties of CoBixFe2-xO4 nanoparticles. The phase identification and morphological studies have been carried out by X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM). Obtained results confirm the presence of single phase spinal structure having space group Fd3m. In addition, FESEM micrographs reveal presence of spherical grains having diameters ranging from 20-130 nm. Further, dielectric studies of the prepared nanoparticles have been performed which suggests different types of conduction mechanism of the charge carriers. Results demonstrates the presence of dielectric relaxation, which is found to be of non-Debye type. Apart from these, Mossbauer study is conducted to observe the distribution of the cobalt and bismuth in the spinel ferrite. Moreover, in this study, effect of gamma irradiation on structural, dielectric and Mossbauer properties for various concentration of Bi have been discussed in detail.
Keywords: Nanoparticles; sol-gel auto combustion; X-ray diffraction (XRD); dielectric; Mossbauer spectra.
Performance Analysis of ZnO based Ultrasonic MEMS Transducer used for Blind Person Navigation
by Hara Prasada Tripathy, Priyabrata Pattanaik, Sashanta Kumar Kamilla
Abstract: Navigation is not an easy task especially without using eye. Creatures like bats and dolphins are navigated by creating ultrasonic wave. The sensory organs help them to create and sense the path without visualizing it. This paper imitates these creatures to propose an ultrasonic based MEMS transducer for blind person navigation. MEMS based acoustic transducers commonly employ the piezoelectric material. This model has been designed by using non-toxic and low cost compound like zinc oxide (ZnO) using COMSOL multiphysics. 2D axis-symmetrical model geometry is designed to imitate like sensory organ to sense the obstacle present 2 meters away from it. An optimized voltage of 5 volt and frequency of 20.103 KHz is applied to the proposed model to create ultrasonic wave. Further, the wave propagation in the air medium is analyzed by using 3D partial differential equation. The pressure waves are studied during transmitting and receiving time. The rebounded wave from the obstacle to the transducer is converted to 30.2mV by the proposed model. The von-misses stress is carried out to study the pressure on transducer surface.
Keywords: Navigation; Ultrasonic Wave; MEMS Transducer; Zinc Oxide (ZnO); COMSOL multiphysics; Von-misses Stress.
Comparison of magnetization and transport properties of processed La0.67Ca0.33MnO3 manganites for technological application
by DIPTI R. SAHU, D.K. Mishra
Abstract: A lot of efforts are being made to look for suitable types of colossal magnetoresistance (CMR) materials with specific composition for technological applications. We have synthesized and performed the magnetization and transport studies on La0.67Ca0.33Mn03 CMR polycrystalline materials prepared using melt and sintering technique. It is observed that the magnetoresistance is enhanced in partially melted sample with increase in insulator-to-metal transition temperature enabling its possible applications at room temperature. This indicates the high degree of spin polarization of the conduction electrons in partially melted sample. It has been observed that grain boundaries disrupt the local magnetic order and alter the electrical conduction of polarized electrons whereas the magnetization behaviour is not significantly affected except the magnitude of the magnetization. This suggests that the magnetic spin alignment in the weak link region of the sintered sample increases the absolute magnetization. The melt processed method is the ideal method to achieve superior magnetic and transport properties for possible major technological application of colossal magnetoreistive devices.
Keywords: CMR; Magnetization; Magnetoresistance; Transport.
Synthesis of Magnesium Oxide Nanopowder via Plasma Processing route
by Sanghamitra Dash, Rakesh K. Sahoo, Saroj K. Singh, Dinesh Singh Chauhan
Abstract: We describe a less time consuming and scalable thermal plasma process for the synthesis of magnesium oxide (MgO) nanoparticles. In this process, argon is used as the plasmagen gas to form argon plasma. In presence of argon plasma magnesite powder was decomposed to form nano magnesia within 10 minutes. This as-synthesized magnesia has been analysed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectrum (FT-IR) for phase, morphology and presence of surface functional groups, respectively. The phase and average crystallite size of the as-synthesized powder was determined from XRD pattern. Further, Raman spectroscopy was used to observe the phase and phase purity. Finally, the spherical shape of the as-formed magnesia powder was observed using TEM.
Keywords: Magnesium oxide; thermal plasma; structure; morphology; spherical particle.
Preparation and characterization of smart polymer-metal nanocomposite: Optical and morphological study
by Binay Bhushan
Abstract: The paper reports a novel polymer-metal nanocomposite. The composite structure is in the form of annular polydiacetylene (PDA) nanovesicles surrounded by silver nanoparticles both on the outer as well as inner surfaces of the vesicle structure. The synthesis route has been described in detail and the rationale behind the synthesis procedure has been discussed. The composite structure has been characterized by UV-Vis spectroscopy while its morphology has been studied based on the result of transmission electron microscopy and electron diffraction pattern. Our synthesis procedure does not require any catalyst, contrary to what has been reported in the literature. The coupling between electrons of PDA and free electrons of silver nanoparticles in the composite system is particularly useful for nonlinear optical applications. We have also outlined some of the strategies that could be explored in future so that such composite system could be a better potential candidate for photonic devices.
Keywords: Polydiacetylene; Silver; Nanoparticles; Nanocomposite.
Aesthetic Improvement Of Transparent Natural Quartz By Heat Treatment At Different Temperature
by Rakesh K. Sahoo, Saroj K. Singh, B.K. Mishra, Biswa Bhusan Dhal
Abstract: Attempt has been made by us to improve the aesthetic value of natural gem variety transparent quartz from of Odisha through heat treatment with cobalt oxide powder and the results are reported. Natural occurring quartz stones were surface cleaned and heat treated at different temperatures with cobalt oxide to alter the color and clarity. A series of experiments by adding cobalt oxide additive at different temperature were carried out to study the alteration of aesthetic values. The change in color and chemistry on the surface of the treated stones with respect to the untreated one were compared. Moreover, in this work improvement in aesthetic value of the quartz stone and its consequent change in surface chemical and physical characteristics before and after heat treatment at different temperatures have been compared and described.
Keywords: Quartz; heat-treatment; Cobalt oxide; surface analysis; Odisha.
Influence of chondroitin 4-sulfate on properties and cell behaviour of collagen hydrogel
by Masrina Mohd Nadzir, Lau Sin Mun, Farah Dhaniyah Anour, Shiplu Roy Chowdhury, Mohd Fauzi Mh Busra
Abstract: In this research, the fabrication of collagen/chondroitin 4-sulfate (C4S) hydrogel scaffold for biomedical applications was studied. The influence of C4S content on physical, mechanical, and biological properties of scaffold were investigated. It was found that high C4S content significantly increased the swelling capacity of scaffold. Furthermore, thermal stability was higher by 5
Keywords: hydrogel scaffold; collagen; chondroitin 4-sulfate; characterization; in vitro.
MM-Wave Double Drift IMPATT Diode: A Comparison of Experimental, Theoretical and Neural Network Approach
by Pravash Tripathy, Sishir Choudhury, Shankar Pati
Abstract: This paper presents the comparison of simulation and experimental output with the neural network results of different materials like Si and GaAs based IMPATT diode at 94 GHz window frequency. The experimental results are nearly equal to simulation results and show a quantitative agreement between theoretical values and experimental output. The experimental results in terms of efficiency and RF power are almost 80-85 % of the simulation results. Rest 15-20 % discrepancy between theory and experiment because of due to several causes like temperature, small-signal approach, parasitic effects, impedance matching problem and proper heat-sink arrangements. The experimental value shows that from silicon double drift impatt diode produced 530 mW with 8.0 % efficiency as compared to the simulation results of 680 mW with 8.5 % efficiency at 94 GHz frequency. At the same frequency our neural network result shows 525 mW with 8.3 % efficiency, which is very close to the experimental results in same design frequency. It shows our neural network approach is a good agreement with experimental results. In the similar way the RF power and efficiency for GaAs double drift impatt diode is 217 mW with 4.5 % as compared to simulated results 210 mW with 7.3 % efficiency. Here by applying the neural network technique, the power is about 215 mW with 4.7 % efficiency. The developed neural network model is used to optimize performance of the diode by taking other wide band gap semiconductor material based IMPATT diode. The model and the results will be very useful for applications in radar and guided missile technology.
Keywords: Silicon; Gallium Arsenide; double drift; IMPATT; RF power; Efficiency; Neural Network.
Study on Thermal Field of a Laser Heated Gemstone Matrix by Finite Element Method
by Radhakanta Dash, Pratima Mishra
Abstract: This paper presents the finite element modelling of the thermal field of a gemstone matrix by laser beam local heating. By using a continuous Gaussian beam of infrared laser a 3D temperature distribution in the gemstone material in the time domain is obtained. A tetrahedral mesh is used to solve the heat conduction equation in the entire 3D-structure. A transient thermal analysis of the interaction of the laser beam with the gemstone matrix reveals the temperature distribution profile throughout the volume of the material. The temperature profile of the computational model of the gemstone is in good agreement with the experimental observations
Keywords: gemstone matrix; alumina; sapphire; laser heating.
Thin membrane with biomimetic hexagonal patterned surface for guided bone regeneration.
by Anurag Satpathy, Rinkee Mohanty, Tapash Ranjan Rautray
Abstract: Polymeric membranes used as a barrier in guided tissue regeneration have undergone several modifications for improved structural, handling and biological properties. Biomaterial surface characteristics are critical in regulating cell function. Physicochemical signals from substrate surfaces stimulate cell behaviour. This paper focuses on fabrication of biodegradable barrier membrane with hexagonal patterned surface for guided tissue regeneration. Hexagonal patterned surfaces were obtained during solvent casting of chitosan solution using a novel method. Obtained barrier membranes were analyzed under stereo and electron microscopy and were assessed for their surface roughness. The hexagonal patterned surface barrier membranes had a significantly higher surface roughness (p<0.001).
Keywords: barrier membrane; chitosan film; hexagonal; patterned surface; surface roughness; guided bone regeneration.
Transport properties on MHD 3-D ethylene glycol and water based colloidal suspensions (Al, CuO & SiC) nanoparticles: A numerical Study
by Santosh Parida, Satya Mishra
Abstract: A comparative study has been made on thermal properties of magnetohydrodynamics (MHD) 3-D ethylene glycol and water based colloidal suspensions (Al, CuO & SiC) nanoparticles. Especially, fluid flow, heat and mass transfer characteristic for MHD three dimensional ethylene glycol based nanofluid is studied in the presence and absence of magnetic field. The involving nonlinear partial differential equations are reduced into ordinary differential equations by using similarity variables and then equations are solved numerically by Runge-Kutta method along with shooting technique. Nusselt number, Sherwood number and Skin friction are calculated and their effect on the flow, heat and mass profiles are discussed graphically. It is interesting to observe that fluid velocity decreases with increase in Al-nanoparticles volume fraction whereas it increases for the nanoparticles CuO and SiC. Increase in the nanoparticles volume fraction increases the temperature both in presence and absence of magnetic parameter for all the three types of nanofluid under study.
Keywords: MHD; Nanofluid; Shooting Technique; Runge-Kutta Method.
Preparation of TiO2 film on Ag and Al electrode for electrochemical bio-sensing application
by Nibedita Patro, Priyabrata Pattanaik, Sushanta Kumar Kamilla
Abstract: In this present, work, titanium dioxide (TiO2) deposited on Ag and Al electrodes were fabricated by sol-gel chemically wet & dry (CWD) method to detect urea. The formation of the polycrystalline TiO2 deposited on Ag and Al substrates were confirmed by X-ray diffraction (XRD) analysis. The XRD analyses of both the samples clearly indicated that some percentage of Ag and Al diffuses into the TiO2 matrix at its interface region. The nature of I-V characteristics showed by the TiO2 on Ag and Al wire electrodes are found to be Ohmic and is perfect to be used for electrochemical sensor or bio-sensor at very low potential value. The performance and response to various concentrations of urea solution and pH level were experimentally studied by using TiO2 coated on Ag and Al as working electrodes with respect to Ag as reference electrode.
Keywords: TiO2 (Titanium dioxide); Chemical wet and dry (CWD) technique; X-ray diffraction (XRD) analysis; Ammonia sensor.
Negative Bias Temperature Instability in strained-Si p-MOSFETs
by Sanghamitra Das, Tara Prasanna Dash
Abstract: Strained-Si MOSFETs are promising performance boosters beyond 90nm technology node. Reliability study of these devices is essential as a very few work has been done in this regard. In this work, we have explored the degradation due to Negative Bias Temperature Instability (NBTI) in strained-Si and bulk Si p-MOSFETs. The output characteristic of the strained-Si p-MOSFET device has been obtained from simulation and it was found to be in good agreement with available experimental data in literature. Then the reliability study of that device has been performed by using a two stage model for defect creation. A comparative study of the drain current degradation and the threshold voltage shift between the strained-Si and Si channel p-MOSFETs has been presented. The transfer characteristic has reduced by 22% and 12% in the strained-Si and Si devices respectively after stressing. The threshold voltage degradation in strained-Si p-MOSFETs is also found to be considerably higher than that in the bulk Si devices due to higher fixed oxide charge and interface trap densities at the strained-Si/SiO2 interface.
Keywords: Negative Bias Temperature Instability; strained-Si channel p-MOSFET;Threshold voltage degradation.
Structure and reaction dynamics of zirconium in the relativistic mean field model
by Mamina Panigrahi, Rabinarayan Panda
Abstract: In the framework of relativistic mean field theory using NL3, NL3*, NLSH, DD-PC1 and DD-ME2 parameter sets, the ground state binding energy, charge radius, quadrupole deformation parameter of three key isotopes of Zr, i.e., 90,92,94Zr has been studied. The results are compared with the experimental data and are found in reasonable agreement. The two-neutron separation energy and β-decay half-life of these isotopes are also evaluated. Total reaction and elastic differential scattering cross-section are also studied for these isotopes as projectile with 12C as target, using above parameter sets in conjunction with Glauber model and results are compared with the experimental data. All these investigations support the abundance of these three isotopes of zirconium.
Keywords: relativistic mean field theory; Glauber model; total nuclear reaction cross-section; differential elastic scattering cross-section.
Synthesis of High Surface Area Boehmite and Alumina by Using Walnut Shell as Template
by Asghar Zamani, Ahmad Poursattar Marjani, Nasim Abdollahpour
Abstract: In the present study high surface area amorphous boehmite and γ-alumina were synthesized using walnut shell as template. This green, simple and useful synthetic protocol was based on the precipitation of aluminum hydroxide as the source of aluminum on biomass in an aqueous phase followed by calcination. The influence of walnut shell was evaluated by varying the calcination atmosphere. Materials were characterized using X-ray diffraction, fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy and N2 adsorption/desorption porosimetry and the results exhibited high surface area for boehmite and γ-alumina. Furthermore, the pore size and surface area of these mesoporous materials can be adjusted by varying the experimental conditions. Additionally, boehmite was studied as the support of vanadium catalyst for the oxidation of alcohols by hydrogen peroxide. We have found that resulting V-loaded material act as an effective catalytic system for the oxidation of a wide range of alcohols in 1,4-dioxane. The catalyst can be recovered and reused four times without loss of activity.
Keywords: green chemistry; biomass; walnut shell; alumina; boehmite; nanostructures; surface area; textural properties; catalysis; vanadium; oxidation; alcohols.
Microscopic study of the role of second nearest neighbour spin density wave coupling and electron hopping on superconducting gap
by Pratima Beura, Kamal Lochan Mohanta, Govinda Chandra Rout
Abstract: We report here a tight binding single band model Hamiltonian to study the role of spin density wave interaction and superconductivity. The Hamiltonian consists of nearest and next nearest neighbour electron hopping between the copper sides. The spin density wave interaction also includes nearest-neighbour and the next-nearest-neighbour spin interactions within a mean field approximation. BCS type superconducting interaction is considered taking d-wave pairing symmetry. By using Zubarevs Green function technique the Hamiltonian is solved. The antiferromagnetic and the superconducting gap equations are derived from the correlation functions and are solved self-consistently technique 100 × 100 grid points of the electron momentum. The evolution of these two order parameters are investigated by varying hole doping concentration, superconducting coupling, spin density wave coupling and second nearest neighbour electron hopping integrals.
Keywords: high-temperature superconductor; d-wave pairing symmetry; spins density wave interaction.
Theoretical Study of Anisotropy in Orbital and Antiferromagnetic Spin Orderings in CMR Manganites
by Saswati Panda, D.D. Sahoo, G.C. Rout
Abstract: We report here a tight binding model study of the interplay of antiferromagnetic (AFM) spin and orbital orderings in the double exchange (DE) model for doped rare earth manganese oxides. In the kinetic energy interaction of conduction electrons, the first and the second nearest hopping integrals are considered. Kubo-Ohata type double exchange interaction is taken between the eg and t2g band electron spins of same site. A Heisenberg type antiferromagnetic spin-spin interaction is considered among the core band electrons, where both nearest and next nearest neighboring interactions are taken in the Heisenberg coupling. The presence of DE interaction induces antiferromagnetism in eg band. Due to the partial filling of eg band Jahn-Teller (JT) distortion is found in eg band. The JT distortion leads to anisotropy in the manganite systems. In the present model we have considered JT distortion as an extra mechanism. Finally the core t2g band electron interaction is considered in the model Hamiltonian. The model Hamiltonian is solved using Zubarevs Greens function technique. The temperature dependent lattice strain and transverse spin fluctuations are calculated from the electron Greens functions and the interplay between these order parameters are studied. Further, we have studied the in-plane anisotropy observed in the AFM spin fluctuation and its effect on the lattice strain.
Keywords: Colossal magneto-resistance; Jahn-Teller effect; Electron correlationsrn.
The study of thermal properties of f-electron systems in the ferromagnetic state
by Asit Kumar Shadangi, Govinda Chandra Rout
Abstract: The rare earth and actinide series of compounds display anomalous physical properties below a characteristic low temperature with very high specific heat coefficient and high effective mass. Here we consider the periodic Anderson model with the repulsive electron-electron interaction within mean-field approximation leading to ferromagnetism in the system. We calculate conduction electron as well as f-electron Greens functions by using Zubarevs Greens function technique and calculate ferromagnetic magnetization numerically and self consistently. The thermal properties like the temperature dependent entropy, specific heat coefficient and electronic specific heat are calculated from the electron free-energy of the f-electron system and are computed numerically. The specific heat coefficient displays high value in heavy fermion state of the system where the position of the f-electron level is away from the Fermi level with the lower strength of hybridization between f and conduction electrons.
Keywords: f-electron system; Entropy; Specific heat.
The tight-binding model study of the role of electron occupancy on the ferromagnetic gap in graphene-on-substrate
by Rashmirekha Swain, Sivabrata Sahu, G.C. Rout
Abstract: We propose here a theoretical model for graphene in its ferromagnetic phase. The Hamiltonian describes electron hoppings up-to-third-nearest neighbors for graphene-on-substrate. The sub-lattice Coulomb interactions within mean-field approach involves the total electron occupancy and ferromagnetic magnetizations. The temperature dependent ferromagnetic magnetization and hence the ferromagnetic gap are derived from the electron Greens functions and are solved self-consistently. The result shows that the magnitude of the ferromagnetic gap and the critical Coulomb interaction strongly depend on total electron occupancy. The critical Coulomb interaction decreases with increase of electron occupancy and the vice-versa.
Keywords: Graphene; Ferromagnetic gap; Coulomb potential.
The theoretical study of the correlation between band filling and Coulomb interaction in the charge gap of graphene-on-substrate in paramagnetic limit
by Rudrashish Panda, Sivabrata Sahu, G.C. Rout
Abstract: The graphene having two dimensional honeycomb lattice is a zero band gap semiconductor where the conduction band and the valance band touch each other at the Dirac point. The two sub-lattices of the honeycomb lattice in pristine graphene are equivalent. When graphene is placed on a suitable substrate, the symmetry of the two sub lattices is broken leading to generation of a gap at the Fermi level. Under these conditions, the Coulomb interaction between the electrons in the two sub lattices play an important role in producing varieties of magnetic, non-magnetic and collective mode interactions. In the present communication, we propose a tight binding model Hamiltonian for graphene on a substrate with nearest neighbor hopping with dispersion in the total Brillouin zone in presence of symmetry breaking interaction due to substrate effect. The Coulomb interactions between the electrons in the two sub lattices are considered within mean-field approximation in the paramagnetic limit. The total Hamiltonian is solved by Zubarevs double time Greens function technique. The electron occupancies of the two sub-lattices are calculated from the correlation functions. Finally the expression for the temperature dependent charge gap i.e. ∆ ̅=U[〈n^a 〉-〈n^b 〉] is derived and calculated numerically. The evolution of the charge gap in graphene is investigated by varying the Coulomb interaction, electron occupancy and substrate induced gap. It is observed that the magnitude of the electron occupancy at A-site becomes larger than that at B-site throughout the temperature range indicating symmetry breaking of the two sub lattices of graphene.
Keywords: Graphene; Paramagnetism; Coulomb Interaction; Magnetic gap.
Development of Self-Assembled Polygalacturonic Acid-Peptide Composites and their Interactions with Mesenchymal Stem Cells for Potential Applications in Tendon Tissue Engineering
by Grant Knoll, Harrison Pajovich, Steven Romanelli, Ipsita Banerjee
Abstract: We have developed a new biomimetic scaffold for potential applications in tendon tissue engineering. The scaffold template was synthesized by conjugating polygalacturonic acid with the dipeptide leucyl-leucine to mimic the leucine rich proteoglycans found in the extracellular matrix of tenocytes. To the template, Type I collagen and an elastin derived peptide were incorporated in order to form the final PG-Leu-Leu-Col-El scaffold. Results indicated the formation of gelatinous, fibrous scaffolds. DSC analysis showed phase changes that included crystallization and thermal melting due to re-organization of the scaffold components. Youngs Modulus was determined to be 832+/-2 MPa. Rheology studies showed that the scaffold maintained a constant G'/ G" ratio over a wide range of angular frequency. Cell studies with bone marrow derived mesenchymal stem cells indicated that the scaffolds promoted cell proliferation and formed three dimensional cell-scaffold matrices. This newly developed scaffold may open new opportunities for applications tissue engineering applications.
Keywords: self-assembly; tissue engineering; composites; biocompatibility; microscale; peptide.
Theoretical Study Of Anisotropic Tunneling Conductance In Iron-based Orbitally Ordered Superconductors.
by Sushree Sangita Jena, S.K. Agarwalla, G.C. Rout
Abstract: We address here the role of Jahn-tellar (JT) distortion on the superconducting gap (SC) in Iron-based superconductors taking into account of the first and second nearest neighbor electron hoppings in the square lattice within one band model approach. The Greens functions are calculated by using Zubarevs Greens function technique. The temperature dependent superconducting gap and the lattice strain are calculated from the correlation functions of the corresponding Greens functions and are computed self-consistently. The temperature dependent gap equations show that the superconducting gap is enhanced with the decrease of second nearest neighbor hopping accompanied by the suppression of lattice strain near the superconducting transition temperature. The second nearest hopping introduces asymmetry in the tunneling conductance.
Keywords: Iron-based superconductors; Jahn-Teller effect; scanning tunneling microscopy.
ELECTROSPINNING PRODUCTION OF PVA/CS/HEMA/nHA BIONANOCOMPOSITE
by Victor Manuel Castano
Abstract: PVA/CS/HEMA/nHA membranes were prepared by electrospinning at different voltages, to produce osteoinductive scaffolds that promote bone extracellular matrix production and in-situ remodeling. Infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) of samples obtained at 25 and 30 kV and 60 min spun, reveal that the presence of chitosan generates some malformations, and glutaraldehyde generates agglomerations in the threads. FTIR do not show significant changes in the functional groups, which indicate that these PVA/CS/HEMA/nHA scaffolds may represent a promising biomaterial for bone tissue engineering.
Keywords: electrospinning; biopolymers; composite; membrane.
Special Issue on: Smart and Nano Materials Applications
Investigation on microstructures and phases of Fe-Ga alloy films deposited by magnetron sputtering
by Jianwu Yan, Ran Zhao, Yingpeng Cha, Qingpeng Li
Abstract: Galfenol (Fe-Ga alloy), as a new magnetostrictive materials, has potentially wide applications in magnetostrictive devices. In this work, Fe-Ga alloy thin films were prepared by slice-style target magnetron sputtering and investigations on microstructures and phases of Fe-Ga alloy films were made to explore the relationship of properties and microstructures. The results show that the component of alloy thin film is related to physical properties of the material itself as well as the area ratio of the patch and target. The phase formed in the films in is disorderly A2 phase with face-centered cubic structure. The films prepared by magnetron sputtering exist in the form of polycrystalline with <110> crystallographic texture perpendicular to the film plane. The structure shape of as-deposited specimens present a maze domain with different contrast and resolution and the magnetic domain decreased with the increase of the Ga content. With the increase of the Ga content, the magnetic domains become more and more irregular. Fe-Ga thin film morphology is related to the growth mode of the film. The microstructures of Fe-Ga alloy films can be controlled by magnetron sputtering technology.
Keywords: Fe-Ga alloy films; magnetron sputtering; magnetic domain; A2 phase.
Special Issue on: Bio-Nano Materials and Drug Delivery Systems
Preparation of Micelle Supported Magnetic Hydroxylated Multi-walled Carbon Nanotubes Based Dispersive Solid-Phase Extraction for the Determination of PAHs in seawater
by Mingyu Wang, Shaojun ZHANG, Jiagan Li, Chengda Zhang, Shouwen Pang
Abstract: Measuring the impact of PAHs in seawater samples is often difficult due to the low concentrations in which they appear and the complexity of the sample matrix. Traditional methods for sample preparation such as liquid-liquid extraction and solid phase extraction require the use of excessive amounts of solvents and reagents, and sample handling. In this work, a micelle supported Fe3O4 magnetic nanoparticles decorated hydroxylated multi-walled carbon nanotubes material was synthesized. The material was facilely synthesized between Fe2+ and carbon nanotubes. The synthesized nanomaterial served as an excellent support for micelles, exhibiting high loading capacity and selectivity. The material could also be negatively charged by adjusting pH, exhibiting excellent extraction efficiency. The prepared material used in dispersive solid-phase extraction (DSPE) for investigation of polycyclic aromatic hydrocarbons (PAHs) from seawater for the first time. The application showed good response (R2 > 0.9981) in the range of 0.02 1.0
Keywords: micelle; hydroxylated multi-walled carbon nanotubes; polycyclic aromatic hydrocarbons; dispersive solid-phase extraction.