Pyrolysis of the hybrid energy cane: thermal decomposition and kinetic modeling using non-isothermal thermogravimetric analysis

Journal of Thermal Analysis and Calorimetry - This work aims to investigate the thermal decomposition and reaction kinetics of the hybrid energy cane, as well as its thermochemical properties....     

Langevin simulations of rod-shaped object alignment by surface flow

Nano or micro-scale rod shaped objects suspended in a liquid flowing on a flat solid surface might be aligned or orientated by the nature of the liquid, type of flow and planar channel geometry containing the flow. Orientation might enhance or inhibit certain chemical reactions between the objects, the underlying surface, other chemicals or with the walls of the vessels holding the flowing suspension. The probability density function describing the orientations of the objects satisfies a Fokker–Planck equation whose solution is obtained with Langevin simulation for different surface flow parameters. The methods developed in the present work enable us to evaluate the orientation probability density function for a range of the Peclet number α covering several orders of magnitude, 10^? 4 ≤ α ≤ 10⁸. The experimental detection of orientation control is obtained optically from the measurement of dichroism and birefringence of the suspension. We describe different methods providing experimental proof of the onset of alignment control.     

The effects of solution structure on the surface conformation and orientation of a cysteine-terminated antimicrobial peptide cecropin P1

The surface structure of an antimicrobial peptide, cecropin P1, immobilized to a gold surface via a terminal cysteine residue was investigated. Using reflection-absorption infrared spectroscopy, surface plasmon resonance, and X-ray photoelectron spectroscopy, the effects of pH, solution conformation, and concentration on the immobilized peptide conformation, average orientation, and surface density were determined. Under all conditions investigated, the immobilized peptides were α-helical in a predominately flat, random orientation. The addition of the reducing agent Tris(2-carboxyethyl) phosphine hydrochloride to the buffer resulted in a twofold increase in immobilized peptide surface density.     

Magnetic crossover effect in Nickel nanowire arrays

A crossover effect in the magnetic reversal mechanism within arrays of Nickel nanowires whose diameter varies from 15 to 100 nm is observed around 50 nm. Hysteresis loops and FMR measurements confirm that nanowire diameter controls effectively the nanowire easy axis as well as the magnetization reversal mechanism. This might be very interesting for spintronic devices based on current-induced domain motion such as non-volatile magnetic memory elements (MRAM) and low Ohmic loss devices.     

Peierls distortion in alloys of quasi-one-dimensional conductors

We have calculated the value of the mean field Peierls transition temperature in a quasi-one-dimensional binary A-B alloy as a function of the relative concentration. This was done in the framework of the single-dimer coherent potential approximation. Reductions in the transition temperature are predicted for isoelectronic constituants.     

Moisture profile measurements of concrete samples in vertical water flow by gamma ray transmission method

Samples of concrete for popular habitation (0.1×0.03×0.1 m) and cellular concrete (0.1×0.05×0.1 m) were submitted to water vertical ascending infiltration. The moisture content spatial and temporal evolution of each sample it was monitored in three halfway positions in a same horizontal line, applying the gamma rays transmission method. The data were taken with a 137Cs (3.7×1010 Bq, 0662 MeV) source, Nal (Tl) of 2×2″ detector coupled to gamma ray spectrometry standard electronic with multichannel analyzer and a micrometric table. For the popular habitation concrete, there was a clear correlation between wetting profiles and concrete strength. The cellular concrete showed a wetting profile compatible to its greater porosity.     

Single reporter for targeted multimodal in vivo imaging

We have developed a multifaceted, highly specific reporter for multimodal in vivo imaging and applied it for detection of brain tumors. A metabolically biotinylated, membrane-bound form of Gaussia luciferase was synthesized, termed mbGluc-biotin. We engineered glioma cells to express this reporter and showed that brain tumor formation can be temporally imaged by bioluminescence following systemic administration of coelenterazine. Brain tumors expressing this reporter had high sensitivity for detection by magnetic resonance and fluorescence tomographic imaging upon injection of streptavidin conjugated to magnetic nanoparticles or fluorophore, respectively. Moreover, single photon emission computed tomography showed enhanced imaging of these tumors upon injection with streptavidin complexed to (111)In-DTPA-biotin. This work shows for the first time a single small reporter (～40 kDa) which can be monitored with most available molecular imaging modalities and can be extended for single cell imaging using intravital microscopy, allowing real-time tracking of any cell expressing it in vivo.     

Improved axial resolution in confocal fluorescence microscopy using annular pupils

The axial image of a thick fluorescent layer is studied in a confocal microscope consisting of either circular or annular pupils. The response for circular pupils is sharper than that for annular pupils if a small pinhole detector is used. But when the size of the pinhole is larger than a certain value, the response in the latter case can become sharper than that in the former. This result implies that for a given detector of finite size, axial resolution in confocal fluorescence microscopy can be improved when an annular lens is used. Our experimental results qualitatively demonstrate the theoretical prediction. The strength of optical sectioning and the axial cross-section of the three-dimensional optical transfer function are also derived from the measured data.