Ground Plane Electrostatically Doped Junctionless Tunnel Field Effect Transistor: Process Immune Design for Suppressed Ambipolarity

Silicon - The incorporation of a highly doped Si layer below the Si film, termed as the ground plane, in the electrostatically doped junctionless tunnel field effect transistor (ED-JLTFET) with...     

Corrosion of steel reinforcements embedded in FRP wrapped concrete

A large number of reinforced concrete (RC) structures that have been damaged due to corrosion of steel reinforcements are rehabilitated with fiber-reinforced polymer (FRP) composites. This paper investigates the progression of corrosion of steel in concrete after it has been treated with surface bonded FRP. Concrete cylinders with embedded steel bars are immersed in salt water and anodic current is passed through the reinforcement to initiate cracking in concrete due to accelerated corrosion of steel. Glass and carbon FRP sheets have been adhesively bonded on the cylinders. Anodic current was continued for specified times. Pull out strength, mass loss, half cell potential of the steel and cell voltage have been reported as metrics of performance of the samples. FRP wrapped samples have shown substantially higher resistance to corrosion.     

Structural Modification in Carbon Nanotubes by Boron Incorporation

We have synthesized boron-incorporated carbon nanotubes (CNTs) by decomposition of ferrocene and xylene in a thermal chemical vapor deposition set up using boric acid as the boron source. Scanning and transmission electron microscopy studies of the synthesized CNT samples showed that there was deterioration in crystallinity and improvement in alignment of the CNTs as the boron content in precursor solution increased from 0% to 15%. Raman analysis of these samples showed a shift of ~7 cm⁻¹ in wave number to higher side and broadening of the G band with increasing boron concentration along with an increase in intensity of the G band. Furthermore, there was an increase in the intensity of the D band along with a decrease in its wave number position with increase in boron content. We speculate that these structural modifications in the morphology and microstructure of CNTs might be due to the charge transfer from boron to the graphite matrix, resulting in shortening of the carbon–carbon bonds.     

Ex Vivo Human Colon Tissue Exposure to Pristine Graphene Activates Genes Involved in the Binding,Adhesion and Proliferation of Epithelial Cells

Toxicology studies on pristine graphene are limited and lack significant correlations with actual human response. The goal of the current study was to determine the response of total colonic human tissue to pristine graphene exposure. Biopsy punches of colon tissues from healthy human were used to assess the biological response after ex vivo exposure to graphene at three different concentrations (1, 10, and 100 µg/mL). mRNA expression of specific genes or intestinal cytokine abundance was assessed using real-time PCR or multiplex immunoassays, respectively. Pristine graphene-activated genes that are related to binding and adhesion (GTPase and KRAS) within 2 h of exposure. Furthermore, the PCNA (proliferating cell nuclear antigen) gene was upregulated after exposure to graphene at all concentrations. Ingenuity pathway analysis revealed that STAT3 and VEGF signaling pathways (known to be involved in cell proliferation and growth) were upregulated. Graphene exposure (10 µg/mL) for 24 h significantly increased levels of pro-inflammatory cytokines IFNγ, IL-8, IL-17, IL-6, IL-9, MIP-1α, and Eotaxin. Collectively, these results indicated that graphene may activate the STAT3–IL23–IL17 response axis. The findings in this study provide information on toxicity evaluation using a human-relevant ex vivo colon model and serve as a basis for further exploration of its bio-applications.     

Effect of zinc concentration on the magnetic properties of cobalt–zinc nanoferrite

Nano-cobalt–zinc ferrite (CZFO) Co_(1?x)Zn_xFe₂O₄ with varied quantities of zinc (x = 0.0, 0.1, 0.2, 0.3, 0.4) have been prepared by solution combustion method. X-ray diffraction and transmission electron microscopy confirmed the size, structure and morphology of the nanoferrites. The addition of zinc in cobalt ferrite has been shown to play a crucial role in enhancing the magnetic properties. Ferromagnetic ordering is observed in nano samples at room temperature. Zn substitution shows maximum saturation magnetization for x = 0.1, that is 56.74 emu/g and then decreases for further increase in Zn substitution. The dependence of Mössbauer parameters viz. isomer shift and hyperfine magnetic field with zinc concentration has been studied. Mössbauer results are also supported by magnetization data. The results obtained from this method make these samples suitable for preparing high quality nanocrystalline ferrite for high density data storage applications.     

Ring opening polymerization of lactide: kinetics and modeling

The ring opening polymerization (ROP) kinetics of L-lactide was studied in bulk at 150, 160, and 180?°C using stannous octoate [Sn(Oct)₂] catalyst and 1-pyrene butanol co-catalyst. The effect of different parameters namely, time and co-catalyst to catalyst ratio was studied on the properties of polylactide. The experimental results showed high conversion of L-lactide. The kinetics of L-lactide ROP follows the co-ordination insertion mechanism. The experimental results obtained were studied to account for the reversible activation, propagation, termination, and validated by modeling using MATLAB. The model developed successfully predicts the monomer conversion and the kinetics of L-lactide ROP.     

Microfabricated PLGA scaffolds: a comparative study for application to tissue engineering

A variety of techniques for the manufacture of biodegradable, three-dimensional scaffolds for tissue engineering have been developed in recent years. In this study, we report and compare two simple methods for fabricating poly( -lactide-co-glycolide) (PLGA) scaffolds with feature sizes of 10–200 μm, which have been developed in our laboratories.

The first technique is based on the use of a microsyringe that makes use of a computer-controlled, three-axis micropositioner, which allows the control of motor speeds and position. A PLGA solution is drawn from the needle of the syringe by the application of a constant pressure of 10–300 mm Hg resulting in controlled polymer deposition of 10–600 μm in diameter. The second technique is based on “soft lithographic” approaches that utilizes a Poly(dimethylsiloxane) (PDMS) mold. The polymer solution is cast on the mold under vacuum. Polymer concentration, solvent composition, and casting conditions influence the integrity and the lateral resolution of the resulting scaffold. Both techniques allow the possibility of constructing three-dimensional architectures that permit the study of cell behaviour in an environment similar to that in vivo, and may provide tools for the construction of engineered tissue.     

Neuroticism and brain responses to anticipatory fear.

Personality is known to influence cognitive and affective functioning as well as the risk of psychiatric disorders. Exploration of the neurobiological correlates of personality traits has the potential to enhance understanding of their significance in development of related psychopathological states. The authors examined the association between individual differences in neuroticism and brain activity in response to threat of electric shocks. Fourteen right-handed healthy men underwent functional MRI during a 5-min experiment that involved repeated presentations of two 30-s alternating conditions. In 1 of these conditions, subjects were told to expect mild but painful electric shocks; there was no possibility of receiving shocks in the other condition. The results revealed that neuroticism correlated positively with the ratings of fear of shock and negatively (indicating suppression) with brain activity from safe to shock conditions in the anterior and posterior cingulate, superior/middle temporal gyrus extending to the hippocampus, precuneus, putamen, thalamus, and middle occipital gyrus. The observations support recent psychophysiological research that has demonstrated reduced processing of pain in subjects with higher levels of neuroticism, especially the anxiety component of this trait. (PsycINFO Database Record (c) 2010 APA, all rights reserved)