Nano-Tubular Cellulose for Bioprocess Technology Development

Delignified cellulosic material has shown a significant promotional effect on the alcoholic fermentation as yeast immobilization support. However, its potential for further biotechnological development is unexploited. This study reports the characterization of this tubular/porous cellulosic material, which was done by SEM, porosimetry and X-ray powder diffractometry. The results showed that the structure of nano-tubular cellulose (NC) justifies its suitability for use in “cold pasteurization” processes and its promoting activity in bioprocessing (fermentation). The last was explained by a glucose pump theory. Also, it was demonstrated that crystallization of viscous invert sugar solutions during freeze drying could not be otherwise achieved unless NC was present. This effect as well as the feasibility of extremely low temperature fermentation are due to reduction of the activation energy, and have facilitated the development of technologies such as wine fermentations at home scale (in a domestic refrigerator). Moreover, NC may lead to new perspectives in research such as the development of new composites, templates for cylindrical nano-particles, etc

Characterization of multiferroic thin films directly deposited on silicon for novel device applications

we have investigated the multiferroic and dielectric properties in Dy modified BiFeO(3) thin films deposited directly on silicon using pulsed laser deposition (PLD) technique. The results support the usability of these films in multiferroic based MEMS devices as well as gate dielectrics for future CMOS applications

Hydrolysis of aluminium metal, synthesis of nano alumina and sol-gel processing of monoliths

High purity alumina is usually prepared using various intermediate aluminium compounds such as aluminium nitrate, aluminium alkoxides etc., as precursors. In fact the above mentioned intermediate aluminium compounds themselves are produced from aluminium metal. The present investigation is concerned with examining the feasibility of using aluminium hydroxides prepared by hydrolyzing aluminium metal, for sol gel processing. The study assumes added significance in view of the claims of Alcoa that it is possible to produce high purity aluminium metal in large quantities economically. During the present investigation sols were prepared by using various hydroxides, ie., bayerite, gibbsite and boehmite. Sol gel transition was observed only in the case of boehmite sol and this was gelated by either forced gelation method to prepare powder or controlled gelation method to prepare monoliths. Transparent Xerogels (boehmite) could be prepared by controlled gelation method but the presence of a thin layer of bayerite often resulted in translucency. Crack free monoliths could be prepared by heating the xerogels at a low heating rate(< 1 degrees C/min). It was found that sol gel processed boehmite transformed to alpha alumina at a relatively lower temperature (similar to 1080 degrees C ) than the as prepared boehmite which transformed at about 1200 degrees C

Observation of magnetoelectric coupling in Bi(0.7)Dy(0.3)FeO(3) thin films at room temperature

Spatial coexistence of ferroelectric and magnetic domains in micrometer scale is confirmed by multimode scanning probe microscopy of pulsed laser deposited Bi(0.7)Dy(0.3)FeO(3) thin films. The observed change in ferroelectric polarization with applied magnetic field proves the coupling between magnetic and ferroelectric order parameters. Moreover, the alignment of magnetic domains with externally applied electric field further confirms the presence of coupling in this system. Remarkably, the effect persists even after the electric field is removed, thereby implying an electric field induced magnetic hysteresis phenomenon in the magnetic domain structure. The results suggest an in-principle usability of this system for multifunctional applications. (C) 200

Comparative study of multiferroic properties of PbTi0.5Fe0.5O3 thin films grown on various substrates

Multiferroic PbTi0.5Fe0.5O3 films are grown by using pulsed laser deposition technique on Si, Pt/Ti/SiO2/Si and SrRuO3/Si substrates. It is found that the PbTi0.5Fe0.5O3 films get modified from tetragonal to orthorhombic while deposited on Si substrate unlike the other two substrates. For Pt/Ti/SiO2/Si and SrRuO3/Si substrates the crystal structure remains tetragonal. More importantly, the magnitude of ferroelectric, magnetic polarization and magneto-electric coupling observed in both tetragonal and orthorhombic phases are good enough for a variety of device applications. It gives flexibility for selecting substrate while fabricating PbTi0.5Fe0.5O3 based multifunctional devices

Influence of process-induced stress on multiferroic properties of pulse laser deposited Bi(0.7)Dy(0.3)FeO(3) thin films

Bi(0.7)Dy(0.3)FeO(3) films that are grown on a Pt/TiO(2)/SiO(2)/Si substrate by the pulsed laser deposition technique exhibit the coexistence of ferromagnetic and ferroelectric ordering at room temperature. Remarkably the removal of La from Bi(0.6)La(0.1)Dy(0.3)FeO(3) (reported earlier) has helped us to enhance magnetic properties to a large extent while keeping the ferroelectric properties of the same order and the leakage current further reduced. Magnetic anisotropy developed non-linearly with the thickness of the films could be correlated with internal stress randomly developed during the growth process. The arbitrary change in the lattice cell parameter c with the thickness of the film also seems to be influenced by the process-induced stress. The saturation polarization (Ps) values scale with the c parameter. The information obtained by this study would be significantly useful while integrating innovative devices using such advanced multiferroic thin films

Study of multiferroic Bi0.7Dy0.3FeO3 based tunable ring inductor

Bi0.7Dy0.3FeO3 (BDFO) exhibiting multiferroicity at room temperature is used as a core material for the first time to fabricate a ring-type inductor. More importantly due to the presence magnetoelectric coupling, the BDFO inductor could be tuned magnetically as well as electrically. It is observed that tunability of this inductor is better in the presence of magnetic field than electrical field. This behaviour is correlated to high electrical loss factor (tan delta) of the core material. The dissipation of electrical energy perhaps impedes the strain induced change in permeability. However, there are chances of improvement if tan delta of BDFO is controlled. Nevertheless, simplicity in fabrication and flexibility in operation make tunable BDFO inductors attractive for novel applications. The results give confidence to work on development of miniaturization of BDFO inductor

Fabrication and characterization of tunable multiferroic Bi0.7Dy0.3FeO3 based on-chip micro-inductor

An optical lithographic process is developed to realize Si compatible on-chip micro-inductor using single phase room temperature multiferroic system like Bi0.7Dy0.3FeO3 (BDFO) as a core material. On-chip inductor is characterized for inductance and Q factor in the frequency range of 1 kHz-1 MHz. The properties are studied at different values of current passing through the coil and also bias applied directly across the BDFO core. Tunability goes on increasing with current and reaches as high as similar to 90% at 0.07 A of DC current passing through the coil whereas similar to 30% tunability is obtained at 10 V of DC voltage applied across the core. It indicates that substantial change in permeability occurs even at low fields due to presence of magnetoelectric (ME) coupling in BDFO system. The use of the single layer multiferroic BDFO core simplifies the on-chip fabrication process. In addition it helps to avoid the formation of defects that are normally formed at the interface of hetero-structures. Consequently it makes the process more reliable. The integration of the on-chip multiferroic micro-inductor would be useful in miniaturizing the inductive components in electronic device circuit. (c) 2013 Elsevier B.V. All rights reserved

Hydrolysis of aluminium metal and sol-gel processing of nano alumina

Aluminium metal has been hydrolysed at 100 degreesC to synthesize boehmite. Gelatinous and dry boehmite were used to prepare stable sol. In the case of gelatinous boehmite, sol was prepared by peptizing and in the case of dry boehmite an ultrasonic bath was used to prepare the sol. Gelation was carried out by heating on a hot plate, which resulted in sol-gel processed powder. For sol-gel processed boehmite the theta --> alpha transformation occurred at 1078 degreesC and for the as prepared boehmite the same occurred at 1206 degreesC. Sol-gel processed powder could be transformed to alpha alumina completely, when calcined at 1000 degreesC for 1 h. (C) 200