Fabrication of poly-3-hexylthiophene/polyethylene oxide nanofibers using electrospinning

P3HT–PEO blend nanofibers were produced by electrospinning from chloroform solutions. A morphological study was carried out as a function of the processing parameters as well as the ratio between the two polymers. The fibers containing at least 60 wt.% of P3HT presented striated surfaces that could be explained by the alignment of the polymer domains along the fiber axis. The structural arrangement of the polymers was found to vary according to the polymers relative contents. The maximum electrical conductivity found for unaligned mats was 0.16 S/cm and increased to 0.3 S/cm when the nanofibers were aligned along a preferential direction.     

Integrating waveform lidar with hyperspectral imagery for inventory of a northern temperate forest

It has been suggested that attempts to use remote sensing to map the spatial and structural patterns of individual tree species abundances in heterogeneous forests, such as those found in northeastern North America, may benefit from the integration of hyperspectral or multi-spectral information with other active sensor data such as lidar. Towards this end, we describe the integrated and individual capabilities of waveform lidar and hyperspectral data to estimate three common forest measurements - basal area (BA), above-ground biomass (AGBM) and quadratic mean stem diameter (QMSD) - in a northern temperate mixed conifer and deciduous forest. The use of this data to discriminate distribution and abundance patterns of five common and often, dominant tree species was also explored. Waveform lidar imagery was acquired in July 2003 over the 1000 ha. Bartlett Experimental Forest (BEF) in central New Hampshire (USA) using NASA's airborne Laser Vegetation Imaging Sensor (LVIS). High spectral resolution imagery was likewise acquired in August 2003 using NASA's Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). Field data (2001-2003) from over 400 US Forest Service Northern Research Station (USFS NRS) plots were used to determine actual site conditions.Results suggest that the integrated data sets of hyperspectral and waveform lidar provide improved outcomes over use of either data set alone in evaluating common forest metrics. Across all forest conditions, 8-9% more of the variation in AGBM, BA, and QMSD was explained by use of the integrated sensor data in comparison to either AVIRIS or LVIS metrics applied singly, with estimated error 5-8% lower for these variables. Notably, in an analysis using integrated data limited to unmanaged forest tracts, AGBM coefficients of determination improved by 25% or more, while corresponding error levels decreased by over 25%. When data were restricted based on the presence of individual tree species within plots, AVIRIS data alone best predicted species-specific patterns of abundance as determined by species fraction of biomass. Nonetheless, use of LVIS and AVIRIS data - in tandem - produced complementary maps of estimated abundance and structure for individual tree species, providing a promising adjunct to traditional forest inventory and conservation biology planning efforts.     

Deposition of aerosol particles on rough surfaces inside a test chamber

We investigated the deposition rate of aerosol particles (diameter between 0.03 and 5 μm) on rough surfaces of wallpapers, wall-plasters, and two types of carpets inside a test chamber. Compared to a smooth aluminum surface, the deposition rate of aerosol particles on the tested surfaces was up to 20 times depending on the surface roughness, mixing intensity, and particle size. A rough surface with a dimensionless surface roughness height k⁺ < 0.06 can be treated as a hydraulically smooth. The estimated deposition rates in this study and those predicted by a deposition model, which incorporates surface roughness, were in good agreement for coarse mode particles (diameter > 1 μm) when k⁺ < 1.04 and for ultrafine particles (diameter < 0.1 μm) when k⁺ < 0.48. The agreement between the model prediction and our estimation was better for coarse mode particles than for ultrafine particles. Deposition of aerosol particles, especially fine particles, needs more empirical investigations aiming at improving the existing models.     

The Effect of Thermal Pre-Treatment on Structure, Composition, Basicity and Catalytic Activity of Mg/Al Mixed Oxides

The goal of this work is to study the effect of thermal pre-treatment of Mg/Al mixed oxides (450–1,050 °C) on their structure, basicity and catalytic activity in transesterification of rapeseed oil. The catalytic activity of Mg/Al catalysts was shown to depend not only on the amount of basic sites, but also on crystallite size of MgO, specific surface area and population of medium/strong basic sites. Moreover, high stability of Mg/Al-550 was established by re-using the catalyst four times. It was associated with negligible magnesium leaching from the solid catalyst to liquid phases.     

O6-Methylguanine-Methyltransferase (MGMT) Promoter Methylation Status in Glioma Stem-Like Cells is Correlated to Temozolomide Sensitivity Under Differentiation-Promoting Conditions

Glioblastoma (GBM) is the most malignant type of primary brain tumor with a very poor prognosis. The actual standard protocol of treatment for GBM patients consists of radiotherapy and concomitant temozolomide (TMZ). However, the therapeutic efficacy of this treatment is limited due to tumor recurrence and TMZ resistance. Recently isolated, glioma stem-like cells (GSCs) are thought to represent the population of tumorigenic cells responsible for GBM resistance and recurrence following surgery and chemotherapy. In addition, MGMT (O6-methylguanine-methyltransferase) methylation is considered as one of the principal mechanisms contributing to TMZ sensitivity of GBM. In this study we have isolated GSCs from 10 adult GBM patients and investigated the relationship between MGMT methylation status and Temozolomide (TMZ) sensitivity of these lines grown either in stem-like or differentiation promoting conditions. Sensitivity to TMZ was significantly associated with MGMT methylation status in cells committed to differentiation but not in stem-like cells. In addition, patients harboring highly methylated MGMT promoters had a longer overall survival. These results reveal the importance of the differentiation process when considering the predictive value of MGMT status in GSCs for clinical response to TMZ.     

Synthesis of New Water‐Soluble Atropisomeric Ligands Derived from the MeOBIPHEP Skeleton: Applications for Asymmetric C?H Bond Formation and Mechanistic Studies

We have extended the methodology developed for the preparation of atropisomeric chiral ligands derived from the MeOBIPHEP ligand to water‐soluble ones. The hydrophilic ligands bearing sodium carboxylate and methylammonium chloride moieties were easily synthesized under mild conditions in a short sequence and in high yields. Their solubility and acid/base properties were also determined. The ruthenium(II) catalysts contain‐ ing 4‐CO₂Na‐ and 3,5‐(CO₂Na)₂‐substituted MeOBIPHEP analogues showed excellent activities and led to the desired hydrogenated products derived from dimethyl itaconate and 2‐(4‐fluorophenyl)‐3‐methylcrotonic acid in ees≥92%. An investigation of the asymmetric hydrogenation of the latter substrate in D₂O as solvent afforded an insight into the mechanism.     

Cluster formation and phase separation in mixtures of sodium κ-carrageenan and sodium caseinate

Mixtures of the polysaccharide κ-carrageenan (KC) and caseinate proteins (SC) from milk were investigated at pH 7 in aqueous solution using confocal scanning laser microscopy and light scattering. Phase separation was observed at higher concentrations and the phase diagram was established. In the mixtures SC was observed to form large aggregates mediated by a relatively small amount of KC. At small KC concentrations the aggregates were initially relatively small and could be characterized by light scattering. At higher KC concentrations or on longer storage at 20 °C, dense clusters with a radius of a few microns were formed that slowly precipitated. The fraction of precipitated protein increased linearly with increasing KC concentration, but was independent of the protein concentration. It increased with decreasing pH from about 20% at pH 8 to 100% at pH 5.     

Carbon nanotube fiber microelectrodes: design, characterization, and optimization

We report on the preparation and interesting electrochemical behavior of carbon nanotube fiber microelectrodes (CNTFM). By combining the advantages of carbon nanotubes (CNT) with those of fiber electrodes, this type of microelectrode differs from CNT modified or CNT containing composite electrodes, because it's made of only CNT without any other components like additives or binders. The active CNT surface is easily regenerated. The performance of CNTFMs has been characterized, among others, by surface modification with phosphomolybdic acid. It is shown that adsorption behavior of these catalyst molecules is highly improved with a controlled orientation of CNT. A better CNT alignment inside the fiber can be achieved by a hot stretching procedure.