Polyaniline itself can be converted to its conductive form from its insulating form by applying an oxidising potential in which polyaniline is converted to its positive charge state. Anions in the ...target solution are driven into the positively charged polymer film by electrostatic force, and this process is reversed when a reduction potential is applied. Consequently, interfacial processes of polyaniline modified electrode make it viable to remove undesirable ions from the target solution. During this process, polyaniline operates as an ion-exchanger by directing specific ions at definite potentials, which is the principle of the electrochemically switched ion-exchange technique. Therefore, polyaniline can be employed as a convenient material to perform as a new ion-exchanger modified film in an acidic environment. On the other hand, an abrupt decrease in the electroactivity of polyaniline at elevated pH values restricts its use in such practical applications. To overcome this problem, copolymerization of aniline and o-toluidine is expedient as it will be able to enhance the electrochemical properties of polyaniline. Hence, several copolymers were synthesised in the presence of different aniline and o-toluidine feedstock ratios. It was found that the surface coverage value of a representative poly(aniline-co-o-toluidine) copolymer film was 139.7 nmol cm−2 compared with 76 nmol cm−2 for pure Pani under identical conditions. In addition, the redox cycling in monomer-free NaF solutions showed that the poly(aniline-co-o-toluidine) film exhibited excellent reversibility between redox reactions at pH 6.60. These outcomes clearly illustrate the contribution of o-toluidine to the electrochemical properties of polyaniline at raised pH medium.
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•Copolymer films of pyrrole and 3,4-ethylenedioxythiophene (EDOT) can be prepared with controllable composition.•Potentiodynamic (cf. potentiostatic) copolymer deposition yields films ...relatively enriched in pyrrole.•Poly(pyrrole-co-EDOT) films have electrochromic properties that depend on deposition conditions.•Templated deposition of poly(pyrrole-co-EDOT) films can be used to visualize latent fingerprints on a metal surface.•Copolymer-enhanced latent fingerprints can be imaged optically, compositionally or topographically.
Latent fingerprints, by definition, require chemical or physical treatment to render them visible. The broadly insulating characteristics of sebaceous fingerprint residue make the deposit act as a “mask”, directing electrochemical processes to regions of bare metal between the residue. We use this effect during electrooxidation of pyrrole (Py) and 3,4-ethylenedioxythiophene (EDOT) to form copolymer films on stainless steel: the outcome is a negative image of the fingerprint. The lower oxidation potential of pyrrole means that the copolymer is enriched in this component; quantitation using XPS shows that this is more pronounced for films deposited potentiodynamically than potentiostatically. Nonetheless, the accessible ranges of solution composition and deposition potential permit controlled deposition of films in which either (or neither) component is dominant. The films are electrochromic in a manner that depends not only on applied potential post-deposition (as expected), but also on deposition potential; this allows visible contrast optimization against the substrate. Poly(Py-co-EDOT) films permit observation of latent fingerprints on stainless steel with high definition of second level details used for identification purposes and, on occasions, finer (third level) detail. Imaging may be accomplished visibly (by film colour), compositionally (by mapping functional groups using vibrational spectroscopy) and topographically (using a 3D microscope).
ICTV Virus Taxonomy Profile: Chrysoviridae Kotta-Loizou, Ioly; Castón, José R; Coutts, Robert H A ...
Journal of general virology,
02/2020, Letnik:
101, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Members of the family
are isometric, non-enveloped viruses with segmented, linear, dsRNA genomes. There are 3-7 genomic segments, each of which is individually encapsidated. Chrysoviruses infect ...fungi, plants and possibly insects, and may cause hypovirulence in their fungal hosts. Chrysoviruses have no known vectors and lack an extracellular phase to their replication cycle; they are transmitted via intracellular routes within an individual during hyphal growth, in asexual or sexual spores, or between individuals via hyphal anastomosis. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the family
, which is available at ictv.global/report/chrysoviridae.
The strategy of combining electroactive polymers and inorganic nanomaterials has been widely explored in recent years in order to improve some of their properties, namely electrocatalysis and ...electrochromism. This report focuses on a new composite prepared through the electropolymerization of the transition metal complex Ni(3-Mesalen), designated as 1 in the presence of WO3 nanoparticles (NPs) and its electrochromic (EC) performance. The WO3 NPs were prepared using tungsten metal powder; their characterization indicated quasi-spherical morphology, high crystallinity and particle sizes in the range 30–40nm. The nanocomposite WO3@poly1 films displayed similar electrochemical responses to those of pristine poly1 films in LiClO4/CH3CN, but higher electroactive surface coverages, an advantage of NPs incorporation in the nanocomposite. The presence of the WO3 NPs in the poly1 matrix was assessed by X-ray photoelectron spectroscopy and scanning electronic microscopy. The nanocomposite presented similar electronic spectra to those of poly1, indicating that the electronic structure of the pristine film is maintained in the nanocomposite, but exhibited lower ε-values for bands associated with charge transfer transitions for high oxidised states, revealing an enhanced stability towards ligand over-oxidation.
The WO3@poly1 nanocomposite showed more favourable EC properties in LiClO4/CH3CN than the pristine film. For typical coverages (Γ=0.06-0.10 μmol cm−2) the composite showed lower switching times (τ=1.3 − 3.6s), higher optical contrast (ΔT≈31%, an improvement of ca. 40%) and better colouration efficiencies (in the range η=104 − 115cm2C−1, improvement of ca. 13 − 22%).
Spatially selective electrodeposition of poly-3,4-ethylenedioxythiophene (PEDOT) thin films on metallic surfaces is shown to be an effective means of visualizing latent fingerprints. The technique ...exploits the fingerprint deposit as an insulating mask, such that electrochemical processes (here, polymer deposition) may only take place on deposit-free areas of the surface between the ridges of the fingerprint deposit; the end result is a negative image of the fingermark. Use of a surfactant (sodium dodecylsulphate, SDS) to solubilise the EDOT monomer allows the use of an aqueous electrolyte. Electrochemical (coulometric) data provide a total assay of deposited material, yielding spatially averaged film thicknesses, which are commensurate with substantive filling of the trenches between fingerprint deposit ridges, but not overfilling to the extent that the ridge detail is covered. This is confirmed by optical microscopy and AFM images, which show continuous polymer deposition within the trenches and good definition at the ridge edges. Stainless steel substrates treated in this manner and transferred to background electrolyte (aqueous sulphuric acid) showed enhanced fingerprints when the contrast between the polymer background and fingerprint deposit was optimised using the electrochromic properties of the PEDOT films. The facility of the method to reveal fingerprints of various ages and subjected to plausible environmental histories was demonstrated. Comparison of this enhancement methodology with commonly used fingerprint enhancement methods (dusting with powder, application of wet powder suspensions and cyanoacrylate fuming) showed promising performance in selected scenarios of practical interest.
•Latent marks on diverse paper types respond mechanistically similarly to the PD reagent.•Silver particles in PD working solution have a size distribution peaked at 880 nm.•Silver particles are ...deposited instantaneously, then grow under diffusional control.•There is no evidence for iron components of the PD redox system in surface deposits.
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We present a detailed mechanistic study of the PD process, focused on the nucleation and growth dynamics of silver particles on fingermarks deposited on a paper surface, from macroscopic (whole fingermark) and microscopic (particle level) perspectives. Conceptually, we separate the outcomes into aspects that precede exposure of the exhibit (relating to the reagent formulation), that relate to the development of the fingermark during immersion in the PD formulation, and that characterise the fully developed mark subsequent to immersion. Initially, dynamic light scattering shows the silver particles in solution to be relatively monodisperse, with a peak particle size of 880 nm. In the second instance, the issue is whether the particles grow to final size in solution then deposit on the surface or deposit as relatively small particles then grow on the surface. To the naked eye, silver deposition is evident after 2 min; corresponding optical profilometry images show evidence of surface-bound particles (mean diameter 2.13 µm) after 30 s. Across the development time (15 min) the particle population density (2.36 ( ± 0.52) x 105 cm−2), is independent of time. During this time, the mean particle diameter increases with the square root of development time to 16.09 µm. The dynamics suggest essentially instantaneous (shorter than observation time) nucleation and diffusionally controlled growth. Surface analysis (EDS) shows the expected high (low) levels of silver on ridge detail (in furrows) but no evidence of iron (from the redox component of the formulation) entrapment at any point on the surface.
Abstract Body mass results from a complex interplay between genetics and environment. Previous studies of the genetic contribution to body mass have excluded repetitive regions due to the technical ...limitations of platforms used for population scale studies. Here we apply genome-wide approaches, identifying an association between adult body mass and the copy number (CN) of 47S-ribosomal DNA (rDNA). rDNA codes for the 18 S, 5.8 S and 28 S ribosomal RNA (rRNA) components of the ribosome. In mammals, there are hundreds of copies of these genes. Inter-individual variation in the rDNA CN has not previously been associated with a mammalian phenotype. Here, we show that rDNA CN variation associates with post-pubertal growth rate in rats and body mass index in adult humans. rDNA CN is not associated with rRNA transcription rates in adult tissues, suggesting the mechanistic link occurs earlier in development. This aligns with the observation that the association emerges by early adulthood.
Aluminum-based batteries are a promising alternative to lithium-ion as they are considered to be low-cost and more friendly to the environment. In addition, aluminum is abundant and evenly ...distributed across the globe. Many studies and Al battery prototypes use imidazolium chloroaluminate electrolytes because of their good rheological and electrochemical performance. However, these electrolytes are very expensive, and so cost is a barrier to industrial scale-up. A urea-based electrolyte, AlCl3:Urea, has been proposed as an alternative, but its performance is relatively poor because of its high viscosity and low conductivity. This type of electrolyte has become known as an ionic liquid analogue (ILA). In this contribution, we proposed two Lewis base salt precursors, namely, guanidine hydrochloride and acetamidine hydrochloride, as alternatives to the urea-based ILA. We present the study of three ILAs, AlCl3:Guanidine, AlCl3:Acetamidine, and AlCl3:Urea, examining their rheology, electrochemistry, NMR spectra, and coin-cell performance. The room temperature viscosities of both AlCl3:Guanidine (52.9 cP) and AlCl3:Acetamidine (76.0 cP) were significantly lower than those of the urea-based liquid (240.9 cP), and their conductivities were correspondingly higher. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) showed that all three electrolytes exhibit reversible deposition/dissolution of Al, but LSV indicated that AlCl3:Guanidine and AlCl3:Acetamidine ILAs have superior anodic stability compared to the AlCl3:Urea electrolyte, as evidenced by anodic potential limits of +2.23 V for both AlCl3:Guanidine and AlCl3:Acetamidine and +2.12 V for AlCl3:Urea. Coin-cell tests showed that both AlCl3:Guanidine and AlCl3:Acetamidine ILA exhibit a higher Coulombic efficiency (98 and 97%, respectively) than the AlCl3:Urea electrolyte system, which has an efficiency of 88% after 100 cycles at 60 mA g–1. Overall, we show that AlCl3:Guanidine and AlCl3:Acetamidine have superior performance when compared to AlCl3:Urea, while maintaining low economic cost. We consider these to be valuable alternative materials for Al-based battery systems, especially for commercial production.
We report the electrochromic properties of a polymeric nanocomposite prepared by potentiodynamic deposition of transition-metal complex Ni(3-Mesalen), designated as 1, in the presence of TiO2 ...nanoparticles (NPs) with an average size of 9.7 ± 1.1 nm. Entrapment of TiO2 NPs in the poly1 matrix was confirmed by several techniques. The nanocomposite TiO2@poly1 films showed similar electrochemical responses to the original (nanoparticle-free) poly1 films, but with higher electroactive surface coverages (Γ), showing the advantage of the nanocomposite preparation. The results indicated that the electronic structure of poly1 was retained in the nanocomposite; nonetheless, a lower ε value was obtained for the charge-transfer band of the former, revealing superior stability of the nanocomposite for ligand high oxidation states. The TiO2@poly1 nanocomposite showed interesting color changes, from yellow (reduced state) to green and russet (oxidized states), with enhanced electrochemical stability, demonstrated by a charge loss of only 7.3% over ca. 10 000 redox cycles surpassing the original polymer film stability: the loss of electroactivity is a factor of ca. 2 less than for pristine poly1. Furthermore, an enhancement of 16.7% in the optical modulation (ΔOD = 0.48) was also observed for the nanocomposite, confirming the benefit of TiO2 incorporation into the EC properties of the original polymer film.
More than 9000 women were followed for a median of 15 years after a diagnosis of benign breast disease. As compared with women in a SEER database, they had an increased risk of subsequent breast ...cancer, especially if the benign lesion showed signs of atypia. A family history of breast cancer and younger age at diagnosis also increased the risk. Cancers developed in either breast, but an excess number occurred in the same breast.
More than 9000 women were followed for a median of 15 years after a diagnosis of benign breast disease. The women had an increased risk of subsequent breast cancer, especially if the benign lesion showed signs of atypia.
Benign breast disease is an important risk factor for a later breast cancer, which can develop in either breast.
1
It encompasses a spectrum of histologic entities, usually subdivided into nonproliferative lesions, proliferative lesions without atypia, and atypical hyperplasias, with an increased risk of breast cancer associated with proliferative or atypical lesions.
2
–
4
The identification of benign breast disease has become more common as the use of mammography has increased, and thus, having accurate risk estimates for women who receive this diagnosis is imperative.
Important questions remain, however, about the degree of risk associated with the common nonproliferative benign entities and . . .
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