Organic dye for dye-sensitized solar cell

Organic dye for a dye-sensitized solar cell (DSSC) comprising at least one electron-acceptor unit and at least one π-conjugated unit. Said organic dye is particularly useful in a dye-sensitized photoelectric transformation element which, in its turn, can be used in a dye-sensitized solar cell (DSSC)

Antimicrobial activity of biogenically produced spherical Se-nanomaterials embedded in organic material against Pseudomonas aeruginosa and Staphylococcus aureus strains on hydroxyapatite-coated surfaces

In an effort to prevent the formation of pathogenic biofilms on hydroxyapatite (HA)-based clinical devices and surfaces, we present a study evaluating the antimicrobial efficacy of Spherical biogenic Se-Nanostructures Embedded in Organic material (Bio Se-NEMO-S) produced by Bacillus mycoides SelTE01 in comparison with two different chemical selenium nanoparticle (SeNP) classes. These nanomaterials have been studied as potential antimicrobials for eradication of established HA-grown biofilms, for preventing biofilm formation on HA-coated surfaces and for inhibition of planktonic cell growth of Pseudomonas aeruginosa NCTC 12934 and Staphylococcus aureus ATCC 25923. Bio Se-NEMO resulted more efficacious than those chemically produced in all tested scenarios. Bio Se-NEMO produced by B. mycoides SelTE01 after 6 or 24 h of Na 2 SeO 3 exposure show the same effective antibiofilm activity towards both P. aeruginosa and S. aureus strains at 0.078 mg ml −1 (Bio Se-NEMO 6 ) and 0.3125 mg ml −1 (Bio Se-NEMO 24 ). Meanwhile, chemically synthesized SeNPs at the highest tested concentration (2.5 mg ml −1 ) have moderate antimicrobial activity. The confocal laser scanning micrographs demonstrate that the majority of the P. aeruginosa and S. aureus cells exposed to biogenic SeNPs within the biofilm are killed or eradicated. Bio Se-NEMO therefore displayed good antimicrobial activity towards HA-grown biofilms and planktonic cells, becoming possible candidates as new antimicrobials

Aerobic growth of Rhodococcus aetherivorans BCP1 using selected naphthenic acids as the sole carbon and energy sources

Naphthenic acids (NAs) are an important group of toxic organic compounds naturally occurring in hydrocarbon deposits. This work shows that Rhodococcus aetherivorans BCP1 cells not only utilize a mixture of eight different NAs (8XNAs) for growth but they are also capable of marked degradation of two model NAs, cyclohexanecarboxylic acid (CHCA) and cyclopentanecarboxylic acid (CPCA) when supplied at concentrations from 50 to 500 mgL-1. The growth curves of BCP1 on 8XNAs, CHCA, and CPCA showed an initial lag phase not present in growth on glucose, which presumably was related to the toxic effects of NAs on the cell membrane permeability. BCP1 cell adaptation responses that allowed survival on NAs included changes in cell morphology, production of intracellular bodies and changes in fatty acid composition. Transmission electron microscopy (TEM) analysis of BCP1 cells grown on CHCA or CPCA showed a slight reduction in the cell size, the production of EPS-like material and intracellular electron-transparent and electron-dense inclusion bodies. The electron-transparent inclusions increased in the amount and size in NA-grown BCP1 cells under nitrogen limiting conditions and contained storage lipids as suggested by cell staining with the lipophilic Nile Blue A dye. Lipidomic analyses revealed significant changes with increases of methyl-branched (MBFA) and polyunsaturated fatty acids (PUFA) examining the fatty acid composition of NAs-growing BCP1 cells. PUFA biosynthesis is not usual in bacteria and, together with MBFA, can influence structural and functional processes with resulting effects on cell vitality. Finally, through the use of RT (Reverse Transcription)-qPCR, a gene cluster (chcpca) was found to be transcriptionally induced during the growth on CHCA and CPCA. Based on the expression and bioinformatics results, the predicted products of the chcpca gene cluster are proposed to be involved in aerobic NA degradation in R. aetherivorans BCP1. This study provides first insights into the genetic and metabolic mechanisms allowing a Rhodococcus strain to aerobically degrade NAs

Tuning of the Photovoltaic Parameters of Molecular Donors by Covalent Bridging

The synthesis of donor-acceptor molecules involving triarylamines and dicyanovinyl blocks is described. Optical and electrochemical results show that rigidification of the acceptor part of the molecule by a covalent bridge leads to a ca. 0.20 eV increase of the band gap due to a parallel increase of the lowest unoccupied molecular orbital level. A preliminary evaluation of these compounds as donor materials in organic solar cells shows that although this structural modification reduces the light-harvesting properties of the donor molecule, it nevertheless induces an increase of the efficiency of the resulting solar cells due to a simultaneous improvement of the open-circuit voltage and fill factor

Linearly π-conjugated oligothiophenes as simple metal-free sensitizers for dye-sensitized solar cells

Four linear oligothiophenes containing 4, 5 and 7 thiophene rings substituted by a variable number of octyl chains attached at the beta-position of some of the thiophene rings and possessing a terminal cyanoacrylic acid anchoring group have been synthesized. Results of UV-Vis absorption spectroscopy and cyclic voltammetry show that as expected the extension of the π-conjugated system leads to a decrease of the optical gap with an increase of the HOMO level. The four compounds have been evaluated as sensitizers in dye-sensitized solar cells (DSSCs) using a iodide/triiodide liquid electrolyte and the results are discussed in terms of the structure–property relationship with regard to the extension of the conjugated system and the number and position of the octyl side chains using N719 as the reference system. A power conversion efficiency of ~7.30% corresponding to 90% of the value given by N719 under identical conditions has been obtained with one of the heptamers

Manipulation of the Open-Circuit Voltage of Organic Solar Cells by Desymmetrization of the Structure of Acceptor-Donor-Acceptor Molecules

The synthesis of acceptordonoracceptor (ADA) molecules based on a septithiophene chain with terminal electron acceptor groups is reported. Using a dicyanovinyl- (DCV) substituted molecule as reference, another symmetrical ADA donor containing thiobarbituric (TB) groups is synthesized and these two acceptor groups are combined to produce the unsymmetrical ADA compound. The electronic properties of the donors are analyzed by cyclic voltammetry and UV-Vis absorption spectroscopy and their photovoltaic properties are characterized on bilayer planar heterojunction cells that include spun-cast donor films and vacuum-deposited C60 as acceptor. Optical and electrochemical data show that replacement of DCV by TB leads to a small increase of the HOMO level and to a larger decrease of the LUMO, which result in a reduced band-gap. The desymmetrized compound presents the lowest oxidation potential in solution but the highest oxidation onset in the solid state, which leads to a significant increase of the open-circuit voltage of the resulting solar cells

Modulated structures in electroconvection in nematic liquid crystals

Motivated by experiments in electroconvection in nematic liquid crystals with homeotropic alignment we study the coupled amplitude equations describing the formation of a stationary roll pattern in the presence of a weakly-damped mode that breaks isotropy. The equations can be generalized to describe the planarly aligned case if the orienting effect of the boundaries is small, which can be achieved by a destabilizing magnetic field. The slow mode represents the in-plane director at the center of the cell. The simplest uniform states are normal rolls which may undergo a pitchfork bifurcation to abnormal rolls with a misaligned in-plane director.We present a new class of defect-free solutions with spatial modulations perpendicular to the rolls. In a parameter range where the zig-zag instability is not relevant these solutions are stable attractors, as observed in experiments. We also present two-dimensionally modulated states with and without defects which result from the destabilization of the one-dimensionally modulated structures. Finally, for no (or very small) damping, and away from the rotationally symmetric case, we find static chevrons made up of a periodic arrangement of defect chains (or bands of defects) separating homogeneous regions of oblique rolls with very small amplitude. These states may provide a model for a class of poorly understood stationary structures observed in various highly-conducting materials ("prechevrons" or "broad domains").Comment: 13 pages, 13 figure