606 research outputs found
Entanglements in marginal solutions: a means of tuning pre-aggregation of conjugated polymers with positive implications for charge transport
The solution-processing of conjugated polymers, just like commodity polymers, is subject to solvent and molecular weight-dependent solubility, interactions and chain entanglements within the polymer, all of which can influence the crystallization and microstructure development in semi-crystalline polymers and consequently affect charge transport and optoelectronic properties. Disentanglement of polymer chains in marginal solvents was reported to work via ultrasonication, facilitating the formation of photophysically ordered polymer aggregates. In this contribution, we explore how a wide range of technologically relevant solvents and formulations commonly used in organic electronics influence chain entanglement and the aggregation behaviour of P3HT using a combination of rheological and spectrophotometric measurements. The specific viscosity of the solution offers an excellent indication of the degree of entanglements in the solution, which is found to be related to the solubility of P3HT in a given solvent. Moreover, deliberately disentangling the solution in the presence of solvophobic driving forces, leads consistently to formation of photophysically visible aggregates which is indicative of local and perhaps long range order in the solute. We show for a broad range of solvents and molecular weights that disentanglement ultimately leads to significant ordering of the polymer in the solid state and a commensurate increase in charge transport properties. In doing so we demonstrate a remarkable ability to tune the microstructure which has important implications for transport properties. We discuss its potential implications in the context of organic electronics and photovoltaics
The Noncommutative Harmonic Oscillator based in Simplectic Representation of Galilei Group
In this work we study symplectic unitary representations for the Galilei
group. As a consequence the Schr\"odinger equation is derived in phase space.
The formalism is based on the non-commutative structure of the star-product,
and using the group theory approach as a guide a physical consistent theory in
phase space is constructed. The state is described by a quasi-probability
amplitude that is in association with the Wigner function. The 3D harmonic
oscillator and the noncommutative oscillator are studied in phase space as an
application, and the Wigner function associated to both cases are determined.Comment: 7 pages,no figure
Microbiome profiling by Illumina sequencing of combinatorial sequence-tagged PCR products
We developed a low-cost, high-throughput microbiome profiling method that
uses combinatorial sequence tags attached to PCR primers that amplify the rRNA
V6 region. Amplified PCR products are sequenced using an Illumina paired-end
protocol to generate millions of overlapping reads. Combinatorial sequence
tagging can be used to examine hundreds of samples with far fewer primers than
is required when sequence tags are incorporated at only a single end. The
number of reads generated permitted saturating or near-saturating analysis of
samples of the vaginal microbiome. The large number of reads al- lowed an
in-depth analysis of errors, and we found that PCR-induced errors composed the
vast majority of non-organism derived species variants, an ob- servation that
has significant implications for sequence clustering of similar high-throughput
data. We show that the short reads are sufficient to assign organisms to the
genus or species level in most cases. We suggest that this method will be
useful for the deep sequencing of any short nucleotide region that is
taxonomically informative; these include the V3, V5 regions of the bac- terial
16S rRNA genes and the eukaryotic V9 region that is gaining popularity for
sampling protist diversity.Comment: 28 pages, 13 figure
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Concentrations of organic contaminants in industrial and municipal bioresources recycled in agriculture in the UK
Many types of bioresource materials are recycled in agriculture for soil improvement and as bedding materials for livestock and have potential for transfer into plant and animal foods. Representative types of industrial and municipal bioresources were selected to assess the extent of
organic chemical contamination, including: (i) land applied materials: treated sewage sludge biosolids), meat and bone meal ash (MBMA), poultry litter ash (PLA), paper sludge ash (PSA) and compost-like-output (CLO), and (ii) bedding materials: recycled waste wood (RWW), dried paper
sludge (DPS), paper sludge ash (PSA) and shredded cardboard.
The materials generally contained lower concentrations of polychlorinated dibenzo-pdioxins/dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) relative to earlier reports, indicating the decline in environmental emissions of these established contaminants. However, concentrations of polycyclic aromatic hydrocarbons (PAHs) remain elevated in biosolids samples from urban catchments. Polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs) were present in larger amounts in biosolids and CLO compared to their chlorinated counterparts and hence are of potentially greater significance in contemporary materials. The presence of non-ortho-polychlorinated biphenyls (PCBs) in DPS was probably due to non-legacy sources of PCBs in paper production. Emerging flame retardant compounds, including: decabromodiphenylethane (DBDPE)and organophosphate flame retardants (OPFRs), were detected in several of the materials. The profile of perfluoroalkyl substances (PFAS) depended on the type of waste category;
perfluoroundecanoic acid (PFUnDA) was the most significant PFAS for DPS, whereas perfluorooctane sulfonate (PFOS) was dominant in biosolids and CLO. The concentrations of
polychlorinated alkanes (PCAs) and di-2-ethylhexyl phthalate (DEHP) were generally much larger than the other contaminants measured, indicating that there are major anthropogenic sources of these potentially hazardous chemicals entering the environment. The study results suggest that continued vigilance is required to control emissions and sources of these contaminants to support the
beneficial use of secondary bioresource materials
Pletismografia respiratória por indutância: estudo comparativo entre calibração por manobra de isovolume e calibração qualitativa diagnóstica em voluntários saudáveis avaliados em diferentes posturas
Noncompliance in people living with HIV: accuracy of defining characteristics of the nursing diagnosis
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