Copper (II) ions and copper nanoparticles‐loaded chemically modified cotton cellulose fibers with fair antibacterial properties

This work describes the release of copper(II) ions from cellulose fibers, which have been chemically modified by periodate‐induced oxidation of cellulose, followed by covalent attachment of biopolymer chitosan. The release of copper(II) ions has been investigated in physiological fluid (PF) and protein solution (PS) both at 37°C. Fibers have demonstrated excellent antibacterial activity against E. coli. Finally, their borohydride‐induced reduction has yielded copper nanoparticle‐loaded fibers, with average diameter of particles, nearly 28.94 nm. The formation of copper nanoparticles has been established by surface plasmon resonance and FTIR spectroscopy. These fibers also show fair biocidal action against E. coli. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Recent trends and developments in infrared heating in food processing

Fruit processing and preservation technologies must keep fresh-like characteristics while providing an acceptable and convenient shelf life as well as assuring safety and nutritional value. Processing technologies include a wide range of methodologies to inactivate microorganisms, improve quality and stability, and preserve and minimize changes of fruit fresh-like characteristics. Infrared (IR) heating offers many advantages over conventional heating under similar conditions, which include reduced heating time, uniform heating, reduced quality losses, versatile, simple and compact equipment, and significant energy saving. The integration of IR with other matured processing operations such as blanching, dehydration, freeze-dehydration, thawing, roasting, baking, cooking has been shown to open up new processing options. Combinations of IR heating with microwave heating and other common conductive and convective modes of heating have been gaining momentum because of increased energy throughput. A number of publications and patents have demonstrated novel and diverse uses of this technology. This review aims at identifying the opportunities and challenges associated with this technology. The effect of IR on food quality attributes is also discussed. The types of equipment commonly used for IR processing have also been summarized.     

Supply chain efficiency: a simulation cum DEA approach

The management of risks within the supply chain and external to it has become highly critical component of supply chain management. Inventory management is a vital tool to mitigate these risks. Lead times and review periods are important parameters in inventory management. The organizations focus on these parameters to enhance the system-wide supply chain performance in terms of services to customers. This paper aims at analyzing the efficiency of total supply chain in context of average fill rate performance. We analyze the efficiency of a hypothetical supply chain network structure which is subjected to time delays due to lead time and inventory review period changes. To understand the optimal relative efficiency among different values of average fill rate performance obtained through simulation, we used Data Envelopment Analysis approach (DEA). Taguchi experimental design procedure is used as a vehicle for conducting the simulation experiments and analyzing its outcome. The proposed integration of simulation with DEA framework provides practical implications to the decision maker as well as connotes to the real world situation where different enterprises compete for the frontier supply chain efficiency.     

Synthesis of nano-TiC powder using titanium gel precursor and carbon particles

The paper presents a novel process for synthesis of nano-size titanium carbide by reaction between titanium bearing precursor gel and nano carbon particles derived from soot at different temperatures in the range of 1300-1580 °C for 2 h under argon cover. The HRTEM studies of TiC powder synthesized by heating at 1580 °C show the presence of cube shaped particles (~ 60-140 nm) and hollow rods (diameter ~ 30-185 nm). The average particle size of crystallites, calculated by Scherer equation is observed to be ~ 35 nm while the surface area-density measurements indicate it to be ~ 113 nm. The surface area decreases with increase in reaction temperature.     

Development and electrical conductivity behavior of copper‐powder‐filled‐epoxy graded composites

This article reports the development and direct‐current (dc) conductivity behavior of copper‐powder‐filled‐epoxy graded composite. Copper‐powder‐filled‐epoxy composites with 10 wt % copper powder and epoxy resin were developed. dc conductivity measurements were performed on the graded composites with an electrometer in the temperature range of 28–146°C. The dc conductivity decreased with an increase in the distance in the direction of the centrifugal force, and this showed the formation of a graded structure. The dc conductivity increased as the copper powder content increased. Two‐phase conduction occurred in all the copper‐filled‐epoxy graded samples. The activation energy calculated with an Arrhenius equation for one sample was 0.88 eV, and this was mainly due to conduction electronic. Another sample had an activation energy of 1.33 eV. Three samples exhibited ionic conduction. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Interconnect challenges for nanoscale electronic circuits

This article provides an overview of the new challenges by nanometer-scale on-chip interconnects. Effects on performance and reliability are addressed, with an emphasis on resistivity, interconnect delay, and current-carrying capability. For more information, contact Kaustav Banerjee, University of California at Santa Barbara, Department of Electrical and Computer Engineering, Room 4151, Engineering I, Santa Barbara, CA; e-mail kaustav@ece.ucsb.edu.     

Studies on Dielectric and a.c. Conductivity Behavior of Activated Carbon-Filled Epoxy-Graded Composites

In this study, an activated carbon-filled epoxy resin gradient composite was developed. The dielectric constant increased gradually with the increase of activated carbon content in the direction of centrifugal force, due to gradual increase in carbon concentration. Dielectric constant and a.c. conductivity increased with increase in temperature. Increase of a.c. conductivity with temperature was due to the formation of the polycondensed rings, which allowed charge transport in the composite. By using the power law σ_a.c. = A ω^s, values of constant A and frequency exponent s were calculated. It has been found that a decrease from sample 1 to 4 due to the increased concentration of activated carbon in the composite. Small values of activation energy obtained at higher frequencies suggest that the conduction in the composite is mainly due to hopping of charge carriers.     

Polyamide Nanocomposites: Investigation of Mechanical,Thermal and Morphological Characteristics

In the present work, polyamide/CaSO₄ nanocomposites were prepared via melt intercalation on twin-screw extruder. Different particle sizes (23, 15, 10 nm) of CaSO₄ were synthesized by in situ deposition technique and its sizes and shape were confirmed on a transmission electron microscope (TEM). The TEM study showed that nano-CaSO₄ has a needlelike or fiberlike structure. Nano-CaSO₄ was added from 1 to 4 wt% in the polyamide. Properties such as Tensile strength, Elongation at Break, Young's Modulus, and hardness were studied. These results were then compared with commercial CaSO₄-filled polyamide composites. There was a propounding effect to be observed on properties of polyamide nanocomposites due to uniform dispersion of nano-CaSO₄ and commercial CaSO₄. The 4 wt% of 10 nm CaSO₄ shows 16% improvement in Tensile Strength compared to commercial CaSO₄ (11%) filled in polyamide composites, whereas, Elongation at Break decreases drastically in 10 nm CaSO₄-filled polyamide nanocomposites up to 22% compared to commercial CaSO₄-filled polyamide composites at 4 wt% loading (11%). Among these properties, Young's Modulus was found to be more effective in 4 wt% loading of 10 nm CaSO₄ and was recorded to be 66% more compared to commercial CaSO₄-filled-in polyamide composites (22%). Moreover, thermal properties such as thermal degradation and flammability were studied by TGA and flame testers. It was found that nano-CaSO₄ was thermally more stable compared to commercial CaSO₄-filled polyamide composites. Extent of dispersion of nano-CaSO₄ was studied along with micro cracks generated during tensile testing using an Atomic Force Microscope (AFM).