Proof of principle for a molecular 1:2 demultiplexer to function as an autonomously switching theranostic device

Cataloged from PDF version of article.Guided by the digital design concepts, we synthesized a two-module molecular demultiplexer (DEMUX) where the output is switched between emission at near IR, and cytotoxic singlet oxygen, with light at 625 nm as the input (I), and acid as the control (c). In the neutral form, the compound fluoresces brightly under excitation at 625 nm, however, acid addition moves the absorption bands of the two modules in opposite directions, resulting in an effective reversal of excitation energy transfer direction, with a concomitant upsurge of singlet oxygen generation and decrease in emission intensity

Induction of triacylglycerol production in Chlamydomonas reinhardtii: Comparative analysis of different element regimes

Cataloged from PDF version of article.In this study, impacts of different element absence (nitrogen, sulfur, phosphorus and magnesium) and supplementation (nitrogen and zinc) on element uptake and triacylglycerol production was followed in wild type Chlamydomonas reinhardtii CC-124 strain. Macro- and microelement composition of C. reinhardtii greatly differed under element regimes studied. In particular, heavy metal quotas of the microalgae increased strikingly under zinc supplementation. Growth was suppressed, cell biovolume, carbohydrate, total neutral lipid and triacylglycerol levels increased when microalgae were incubated under these element regimes. Most of the intracellular space was occupied by lipid bodies under all nutrient starvations, as observed by confocal microscopy and transmission electron micrographs. Results suggest that sulfur, magnesium and phosphorus deprivations are superior to nitrogen deprivation for the induction triacylglycerol production in C. reinhardtii. On the other hand, FAME profiles of the nitrogen, sulfur and phosphorus deprived cells were found to meet the requirements of international standards for biodiesel. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved

Turfgrass species response exposed to increasing rates of glyphosate application

To investigate the response of nine turfgrass species exposed to increasing rates of glyphosate application, the dry matter production, visual leaf injury symptoms (e.g., chlorosis and necrosis) and the concentrations of shikimate and mineral nutrients were determined in shoots. The rates of foliar glyphosate application were 0%, 5% (1.58 mM), and 20% (6.32mM) of the recommended application rate for weed control. In general, there was a negative and weak correlation between the intensity of visual injury and relative decreases in shoot dry matter production caused by glyphosate application. The decreases in shoot dry matter production and the severity of leaf damage pronounced by increasing glyphosate rate showed a substantial variation among the turfgrass species. Of the turfgrass species tested, Festuca arundinacea ‘Falcon’ and Buchloe dactyloides ‘Bowie’were selected as the most tolerant and sensitive species to applied sublethal rates of glyphosate as judged from visual injury ratings, respectively. At the highest glyphosate rate, shoot dryweightwas decreased by 4-fold in Bowie and only 1.6-fold in Falcon. When glyphosatewas not applied, shoot shikimate concentration of all species was very low and below 2.8mol g−1 FW (fresh weight). Glyphosate applications resulted in increases in shoot shikimate concentration with substantial variations among species. At 6.32mM glyphosate treatment, shikimate concentration ranged between 156.1mol g−1 (F. rubra, Ambrose) and 16.5mol g−1 FW (F. rubra, Cindy Lou). However, the highly sensitive and the tolerant genotypes were not different in shoot shikimate concentrations. Even, in the case of some genotypes, high glyphosate tolerance is accompanied by higher shoot concentrations of shikimate. Depending on the turfgrass species and mineral nutrients tested, increasing glyphosate application either did not affect or reduced mineral nutrient concentrations. In the case of decreases in shoot concentration of mineral nutrients, the decreases in Ca, Mg, Mn and Fe were most distinct. The results obtained indicate existence of a large genetic variation in tolerance to glyphosate toxicity among the turfgrass species. This differential variation in tolerance to glyphosate could not be explained by the changes in shoot concentrations of shikimate and mineral nutrients

Atropisomeric Dyes: Axial Chirality in Orthogonal BODIPY Oligomers

Cataloged from PDF version of article.A dissymmetrically substituted orthogonal BODIPY dimer and an orthogonal BODIPY trimer exist as two stable conformers, which are in fact atropisomeric enantiomers. The racemic mixture can be separated by HPLC using a chiral stationary phase. These enantiomeric derivatives hold great potential as chiral agents in asymmetric synthesis, fluorogenic/chromogenic sensing, and biological applications

PEGylated calix[4]arene as a carrier for a Bodipy-based photosensitizer

Cataloged from PDF version of article.Heavy atom substituted Bodipy compounds, unlike the parent chromophore, undergo rapid intersystem crossing to generate singlet oxygen, which is the primary cytotoxic agent exploited in PDT. In this work, we show that an organic soluble calix[4]arene can be functionalized by Knoevenagel reaction and then converted into an amphiphilic photosensitizer in a few steps. In addition to generating a potentially useful photosensitizer, the sequence of reactions is the first use of a Bodipy dye as a chromophoric/fluorogenic label without the typical reactive functional groups. 2013 Elsevier Ltd. All rights reserved

Proof of principle for a molecular 1 : 2 demultiplexer to function as an autonomously switching theranostic device

Guided by the digital design concepts, we synthesized a two-module molecular demultiplexer (DEMUX) where the output is switched between emission at near IR, and cytotoxic singlet oxygen, with light at 625 nm as the input (I), and acid as the control (c). In the neutral form, the compound fluoresces brightly under excitation at 625 nm, however, acid addition moves the absorption bands of the two modules in opposite directions, resulting in an effective reversal of excitation energy transfer direction, with a concomitant upsurge of singlet oxygen generation and decrease in emission intensity. © The Royal Society of Chemistry 2013

Design and synthesis of soluble dibenzosuberane-substituted fullerene derivatives for bulk-heterojunction polymer solar cells

Cataloged from PDF version of article.Two new dibenzosuberane-substituted fullerene derivatives, dibenzosuberane-C60 monoadduct (DBSCMA) and bis-adduct (DBSCBA) were synthesized using a classical cyclopropanation reaction via a tosylhydrazone route for application as acceptor materials in polymer solar cells (PSCs). DBSCBA shows good solubility in common organic solvents and both derivatives were characterized by 1HNMR, 13C NMR, MALD-TOF, elemental analysis and UV-vis absorption measurements. The shift of fullerene energy levels induced by the dibenzosuberane substitution was investigated by using theoretical simulations and ultraviolet photoelectron spectroscopy. Bulk-heterojunction PSCs based on poly (3-hexylthiophene) (P3HT) and dibenzosuberane-C60 derivatives were fabricated and optimized by adjusting the donor/acceptor ratio and using thermal annealing and solvent additive. The morphologies of the active layers processed under different conditions were also examined by atomic force microscopy. When tested under an illumination of AM 1.5 G at 100 mW/ cm2, the highest power conversion efficiency of the devices using DBSCBA is 3.70% which is superior to that of conventional P3HT:PCBM devices. © 2013 Elsevier B.V

Effects of thermal annealing on the morphology of the AlxGa(1x)N films

Cataloged from PDF version of article.Effects of thermal annealing on the morphology of the AlxGa(1-x)N films with two different high Al-contents (x=0.43 and 0.52) have been investigated by atomic force microscopy (AFM). The annealing treatments were performed in a nitrogen (N-2) gas ambient as short-time (4 min) and long-time (30 min). Firstly, the films were annealed as short-time in the range of 800-950 degrees C in steps of 50-100 degrees C. The surface root-mean-square (rms) roughness of the films reduced with increasing temperature at short-time annealing (up to 900 degrees C), while their surface morphologies were not changed. At the same time, the degradation appeared on the surface of the film with lower Al-content after 950 degrees C. Secondly, the Al0.43Ga0.57N film was annealed as long-time in the range of 1000-1200 degrees C in steps of 50 degrees C. The surface morphology and rms roughness of the film with increasing temperature up to 1150 degrees C did not significantly change. Above those temperatures, the surface morphology changed from step-flow to grain-like and the rms roughness significantly increased. (C) 2009 Elsevier Ltd. All rights reserved