We report an approach to the development of advanced structural composites based on engineered multiscale carbon nanotube-carbon fiber reinforcement. Electrophoresis was utilized for the selective deposition of multi- and single-walled carbon nanotubes (CNTs) on woven carbon fabric. The CNT-coated carbon fabric panels were subsequently infiltrated with epoxy resin using vacuum-assisted resin transfer molding (VARTM) to fabricate multiscale hybrid composites in which the nanotubes were completely integrated into the fiber bundles and reinforced the matrix-rich regions. The carbon nanotube/carbon fabric/epoxy composites showed approximately 30% enhancement of the interlaminar shear strength as compared to that of carbon fiber/epoxy composites without carbon nanotubes and demonstrate significantly improved out-of-plane electrical conductivity.

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Inkjet printing of electrode using copper nanoparticle ink is presented. Electrode was printed on a flexible glass epoxy composite substrate using drop on demand piezoelectric dispenser and was sintered at 200°C of low temperature in N 2 gas condition. The printed electrodes were made with various widths and thickness. In order to control the thickness of the printed electrode, number of printing was varied. Resistivity of printed electrode was calculated from the cross-sectional area measured by a profilometer and resistance measured by a digital multimeter. Surface morphology of electrode was analyzed using scanning electron microscope (SEM) and atomic force microscope (AFM). From the study, it was found that 10 times printed electrode has the most stable grain structure and low resistivity of 36.7 nX m.

In a companion paper [1] a process model was developed for investigation of residual stress development during autoclave or hot press processing of thermosetting polymer matrix composites. Several material property characterization studies are re quired as input to this model. The present paper summarizes the results of the character ization studies required for input to the model and validation of the model is accomplished by the intermittent cure of unsymmetric cross-ply laminates in which the processing- induced residual curvatures are measured. An IM6/3100 graphite/bismaleimide composite system was chosen for the study. Longi tudinal and transverse mechanical properties were shown to increase during the cure cycle due to increase in matrix strength and stiffness and development of the fiber/matrix bond. Thermal strains were shown to remain relatively constant during cure. Chemical strains occur early in the cure cycle and are completed before cure is fully developed. The vis coelastic mechanical response of BMI is strongly dependent on the cure state. At low cure states the creep response is quite significant. As full cure is approached, the material becomes predominantly elastic. Based on the measured input data, the viscoelastic analy sis showed that the contribution of chemical strains to residual stress was less than 4% for a typical cure cycle. A good correlation was obtained between model predictions and ex perimental warpage data for the cure cycle investigated.

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The main objective of the present study is to establish the relationships between the process variables and the quality of thermoplastic composite laminates fabricated by tape placement. The quality parameters considered in the process modeling are interlaminar bond strength, weight loss through thermal degradation, and crystallinity. Stress, heat transfer, crystallization, degradation, and bonding models are developed. These models relate the process parameters (e.g., roller velocity, roller pressure, heat input) to temperature, stress, and crystallinity distributions, degradation weight loss, and degree of bonding within the composite. These relationships are used to develop a process window to ensure product quality. The process parameters are then optimized to reduce the lay-up time.

The control and reduction of processing-induced residual stresses has been investigated by modifying processing conditions for a graphite/BMI composite material. The effects of dwell temperature, dwell time, cool-down rate, cool-down pres sure, and postcure on residual stresses were investigated using unsymmetric cross-ply laminates. The effects on transverse mechanical properties were also measured. Experi mental results have shown that residual stresses can be reduced by as much as 25-30% while retaining or enhancing transverse mechanical properties by curing at lower tempera tures for longer times or utilizing an intermediate low-temperature dwell in three-step cure cycles. Overall process cycle times are not lengthened for three-step curing.

Acetohydroxyacid synthase (AHAS) is a thiamin diphosphate-(ThDP-) and FAD-dependent enzyme that catalyzes the first common step in the biosynthetic pathway of the branched-amino acids such as leucine, isoleucine, and valine. The genes of AHAS from Mycobacterium tuberculosis were cloned, and overexpressed in E. coli and purified to homogeneity. The purified AHAS from M. tuberculosis is effectively inhibited by pyrazosulfuron ethyl (PSE), an inhibitor of plant AHAS enzyme, with the IC 50 (inhibitory concentration 50%) of 0.87 lM. The kinetic parameters of M. tuberculosis AHAS were determined, and an enzyme activity assay system using 96-well microplate was designed. After screening of a chemical library composed of 5600 compounds using the assay system, a new class of AHAS inhibitor was identified with the IC 50 in the range of 1.8-2.6 lM. One of the identified compounds (KHG20612) further showed growth inhibition activity against various strains of M. tuberculosis. The correlation of the inhibitory activity of the identified compound against AHAS to the cell growth inhibition activity suggested that AHAS might be served as a target protein for the development of novel anti-tuberculosis therapeutics.