Mapping of electrostatic potential in deep submicron CMOS devices by electron holography

Quantitative two-dimensional maps of electrostatic potential in device structures are obtained using off-axis electron holography with a spatial resolution of 6 nm and a sensitivity of 0.17 V. Estimates of junction depth and variation in electrostatic potential obtained by electron holography, process simulation, and secondary ion mass spectroscopy show close agreement. Measurement artifacts due to sample charging and surface "dead layers" do not need to be considered provided that proper care is taken with sample preparation. The results demonstrate that electron holography could become an effective method for quantitative 2D analysis of dopant diffusion in deep-submicron devices.     

Zero-n gap soliton

Periodic structures consisting of alternating layers of positive-index and negative-index materials have a novel bandgap at the frequency at which the average refractive index is zero. We show that, in the presence of a Kerr nonlinearity, this zero-n gap can switch from low transmission to a perfectly transmitting state, forming a nonlinear resonance or gap soliton in the process. This zero-n gap soliton is omnidirectional, in contrast to the usual Bragg gap soliton of positive-index periodic structures.     

Association of uranium with colloidal and suspended particulate matter in Arabian sea near the west coast of Maharashtra (India)

The purpose of the present study is the association of natural uranium in seawater with colloidal and suspended-particulate matter was determined. The separation of suspended particulate material (>0.45 µm) and colloidal fraction (as dissolved fractions) in seawater were done by suction and ultra filtration techniques. Seawater samples were collected at 1 km away from the shore and subjected to sequential fractionation in nine stages ranging from 2.7 µm to 1.1 nm. Suspended particulate matter were separated in three different size groups namely >2.7 µm, <2.7–>0.45 µm and <0.45–>0.22 µm by suction filtration using cellulose acetate and nitrate membranes filters. To concentrate the solution with colloidal particles <0.22 µm–1.1 nm (0.5 k Nominal Molecular Weight cut-off Limit {NMWL}), the solution obtained from filtration through <0.22 µm was passed through stirred ultra-filtration cell. The pH and conductivity at different stages of fractionation (dissolved) showed minor variations. The concentration of uranium was measured in suspended and dissolved fractions by using a pulsed nitrogen laser at 337.1 nm. In order to evaluate the role of mineral colloids in various stages of filtration, concentration of calcium, magnesium, potassium were measured by using ion chromatography and atomic absorption spectrometry. The clay mineral at seawater pH (approximately 8) behave as negative ions and provides binding site for the positively charge species of uranium. Among the dissolved fraction, the maximum concentrations of colloidal uranium was observed about 4 times higher than that compared to average concentration of 6.93±3.10 ppb in other fractions. In the case of suspended particulate matter, the concentration of uranium was below detection limits (<1 ppb). The maximum concentration of Ca, Mg and K in the dissolved fraction were in the <1.1 nm fraction, while for suspended particulate matter, the concentration of Ca, Mg and K decreased with the decrease in size and it is highest in the fraction of 0.22 –0.45 µm.This revised version was published online in November 2005 with corrections to the Cover Date.     

Electrochemical Tracing of Butein Using Carbon Nanoparticles Interfaced Electrode Processed from Biowaste

Nanoparticles of carbon derivatized from pyrolysis of biowaste oil palm leaves were processed as electrochemical transducer material at the interface of glassy carbon electrode. This modified electrode exhibits convincing electron‐transfer property for voltammetric and chronoamperometric quantification of clinically important phytochemical, butein, without the use of external redox mediator and enzyme. A reversible two‐electron transfer redox property observed from butein is distinct at the electrode interface and the current density is found to be superior in phosphate buffered saline electrolyte at pH 7.0. Carbon nanoparticles interfaced electrode system displayed a good stability and sensitivity for butein with a detection limit of 7.6 μM and a dynamic detection concentration ranging from 10 to 100 μM. This bio‐waste translated carbon nanoparticle represent a promising electrode material for various flavonoids detection useful for biological studies.     

Photo-leucine incorporation reveals the target of a cyclodepsipeptide inhibitor of cotranslational translocation

Photoaffinity labeling is a powerful tool to identify protein targets of biologically active small molecules, yet is often limited by the size, chemical properties, and availability of photoreactive groups. We report an improved synthesis of photo-leucine, a diazirine-based photoreactive analogue of leucine, and demonstrate its incorporation into a cyclodepsipeptide inhibitor of cotranslational translocation. Photoaffinity labeling in a crude membrane fraction, followed by "click chemistry" with a rhodamine-azide reporter, enabled the identification of Sec61alpha, the structural core of the Sec61 translocation channel, as the inhibitor's target.     

Absorption and desorption of organic liquids in elastic superhydrophobic silica aerogels

The experimental results of the studies on the absorption and desorption of organic liquids in elastic superhydrophobic silica aerogels, are reported. The elastic superhydrophobic aerogels were prepared using methyltrimethoxysilane (MTMS) precursor by a two-step sol-gel process followed by supercritical drying. Monolithic superhydrophobic silica aerogels were used as the absorbents. In all, four alkanes, three aromatic compounds, four alcohols and three oils were used. The absorption property of the aerogel was quantified by the mass and moles of the organic liquid absorbed by unit mass of the aerogel. The superhydrophobic aerogels showed a very high uptake capacity and high rate of uptake. The desorption of solvents and oils was studied by maintaining the as-absorbed aerogel samples at various temperatures and weighing them at regular time intervals until all the absorbed liquid got totally desorbed. This was verified by measuring the weights of the aerogel samples before and after desorption. The transmission electron micrograph observations showed that the aerogel structure was not much affected by the solvent absorption, while the oil absorption led to the shrinkage resulting in a dense structure after the desorption. In all the cases, the aerogels retained hydrophobicity and could be re-used as absorbents.     

Neuropeptide delivery to the brain: a von Willebrand factor signal peptide to direct neuropeptide secretion

Background  

Multiple neuropeptides, sometimes with opposing functions, can be produced from one precursor gene. To study the roles of the different neuropeptides encoded by one large precursor we developed a method to overexpress minigenes and establish local secretion.     

Enhanced electrical properties of CuO:CoO decorated with Sm2O3 nanostructure for high-performance supercapacitor

Journal of Solid State Electrochemistry - In the present investigation, we have synthesized samarium (Sm) nanoparticles (NPs) and anchored them onto the surface of CuO:CoO nanostructure (NS) by...