This work aims to improve the outstanding thermal and mechanical properties of commercialized wholly aromatic polyamide fibers (i.e., aramids), by crosslinking the materials. The introduction of a ...reactive azide group into the polymer structure leads to functional aramids. Crosslinking processes can be easily performed using an inexpensive thermal treatment after fiber spinning with current spin production facilities.
This work describes the strategy of crosslinking aromatic polyamides to increase the outstanding thermal and mechanical performances of these materials. The introduction of a reactive azide group into the polymer structure leads to a 3D network after transformation and upon heating. An important fact is that cross‐linking can be easily achieved with current aramid fiber production facilities.
This paper describes the preparation of a hydrophilic copolymer membrane with two comonomers: 1-vinyl-2-pyrrolidone (commercial) and a new water insoluble piperazinedione derivative, which is a ...fluorogenic mercury sensing motif. The dense membrane permitted the fluorogenic detection of Hg²⁺ in aqueous media. The sensitivity of the membrane this cation was significantly high, with a detection limit of 10ppt. This limit of detection is much lower than that of DMSO/water solutions of the sensing monomer, which is 10ppb, and significantly lower than the maximum contaminant level (EPA) in drinking water, 2ppb.
A report on the syntheses, thermal, mechanical and dielectric characterizations of two novel polymeric acrylic materials with azide groups in their pendant structures is presented. Having the same ...general structure, these polymers differ in length of oxyethylene units in the pendant chain -CONH-CH₂CH₂-(O-CH₂CH₂)
N₃, where n is 1 (poly(
-(2-(2-azidoethoxy)ethyl)methacrylamide), PAzMa1) or 2 (poly(
-2-(2-(2-azidoethoxy)ethoxy)ethyl)methacrylamide), PAzMa2), leading with changes in their dynamics. As the thermal decomposition of the azide group is observed above 100 °C, dielectric analysis was carried out in the temperature range of -120 °C to 100 °C. Dielectric spectra of both polymers exhibit in the glassy state two relaxations labelled in increasing order of temperature as
- and
-processes, respectively. At high temperatures and low frequencies, the spectra are dominated by ohmic conductivity and interfacial polarization effects. Both, dipolar and conductive processes were characterized by using different models. Comparison of the dielectric activity obtained for PAzMa1 and PAzMa2 with those reported for crosslinked poly(2-ethoxyethylmethacrylate) (CEOEMA) was performed. The analysis of the length of oxyethylene pendant chain and the effect of the methacrylate or methacrylamide nature on the dynamic mobility was analysed.
The introduction of host units, also called binding sites or receptor subunits, and fluorescence or chromogenic signaling motifs into the lateral or into the main polymer chain opens the way for ...cutting-edge applications related to the selective interaction of these chemical sites with guest or target molecules (i.e., cations, anions or neutral molecules). Thus, the good mechanical properties of these polymers permit the design and preparation of "á la carte" fluorogenic or colorimetric probes for sensing diverse analytes. These polymeric probes may work in organic or aqueous solutions and, most importantly, in the solid state, as finished materials, can operate in aqueous media, permitting the preparation of "naked-eye" solid probes to be used by non-specialist personnel, for example, to control the concentration of analytes in chemical industries or to test whether environmental polluting chemicals exceed the legal limits.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The distribution of the allochthonous crab
Percnon gibbesi
and its relationships with other benthic invertebrate species was assessed inside the marine reserve of Cabo de Palos—Islas Hormigas ...(Mediterranean sea, Spain) and neighbouring non-protected sites. Although a significant spatial variability was detected at finer spatial scale, there was no influence of protection measures or insularity on the abundance of
P. gibbesi
. The presence of small holes, encrusting algae and low slope favour the colonization success of this crustacean, and the spatial distribution of these habitat features could explain the observed pattern. The abundance of
P. gibbesi
was similar to that of native crab species; however, a non-significant negative relationship between the abundance of
P. gibbesi
and native crabs (
Pachygrapsus marmoratus
and
Eriphia verrucosa
), urchins (
Arbacia lixula
and
Paracentrotus lividus
) and a snail (
Phorcus turbinatus
) was observed. This work highlights the importance of monitoring alien crab population densities taking structural habitat and other potentially influential factors into account and the likely effect of this alien species on the native ones.
Display omitted
•Films based on VP and HEA were prepared by radical polymerization.•The synthesised sulfadiazine moiety (SDZ-MA) was chemically anchored to the film.•The film (FSDZ-MA) presented ...improved antibacterial activity and good biocompatibility.
Microbial colonisation of synthetic materials is a great concern in many fields, e.g., in implant surgery and medical devices; therefore biocompatible hydrophilic organic materials with inherent antimicrobial properties are of current research interest. In this work, we describe the preparation of antibacterial and biocompatible polymeric film based on N-vinyl-2-pyrrolidone (VP) and 2-hydroxyethyl acrylate (HEA), using ethyleneglycol dimethacrylate (EGDMA), and synthetic acrylic monomer containing sulfadiazine chemically anchored. The synthesised polyvinylpyrrolidone (PVP)-based films were characterized by different techniques (1H and 13C NMR, ATR-FTIR, SEM, and TGA). In this study, the biophysical responses of bacteria and L929 cells towards the prepared materials as model device surfaces were evaluated. The membrane that contains the anchored sulfadiazine moiety showed excellent antibacterial activity against Escherichia coli as well as good biocompatibility. Based on the experimental results, this material is a good candidate for medical applications as a biomaterial.
The role of Marine Protected Areas on distinct life stages of Mediterranean reef fish species (classified on the basis of their economic value and mobility categories) was assessed in a network of ...marine reserves in SE Spain. Only abundance and biomass of adult of both commercial and demersal species were positively affected by protection. Gradients across reserve boundaries (as a clue to the occurrence of spillover) were observed for fish abundance but not for biomass, indicating a protected fish assemblage with a predominance of small-sized individuals. Also, post-larvae of commercial species were negatively related to protected zones. Active selection of settlement preferred habitats, larval accumulation favoured by the geomorphological configuration of the coast or mixed effects has been proposed as possible explanations. Juveniles showed high spatial variability resulting in a lack of response to fishing protection measures. We highlight the need of including early life stages and overall suitable habitats for them when designing MPA networks due to the crucial importance of these stages to successful fulfillment of MPA objectives.
•Only adult of commercial and demersal species were positively affected by protection.•Spillover of small sized fish was observed.•Post-larvae of commercially important species were negatively related to protection.•Recruits were not affected by protection due to high spatial variability.•Habitat requirements and lack of surveillance may have contributed to results.
► We prepare a fluorogenic sensory film, or dense membrane, capable of detecting Cr(VI) in water media. ► The solid system shows a potential for use as a solid kit for “dip-in” Cr(VI) detection in ...aqueous environments. ► The sensory membrane is capable of differentiating between Cr(VI) and less harmful Cr(III). ► The detection limit (LOD) of the sensory material is 1ppb.
A fluorogenic sensory film, or dense membrane, capable of detecting Cr(VI), Fe(III), and Hg(II) in water was prepared. The film was prepared by a bulk radical polymerization of different comonomers, one of which contained a piperazinedione motif as sensory fluorophore. The film exhibited gel-like behavior and was highly tractable, even after being swollen in water. The sensing conditions were chosen to overcome interference from iron and mercury cations, giving rise to a material with a detection limit of 1ppb for Cr(VI).
Latent infection with Mycobacterium tuberculosis is defined by a positive IFN-γ release assay (IGRA) result in the absence of active tuberculosis. Only few, mostly monocentric studies have evaluated ...the role of IGRAs to predict the development of tuberculosis in recent contacts in low-incidence countries of tuberculosis.
To analyze IGRA results and the effect of preventive chemotherapy on tuberculosis progression rates among recent contacts.
Results from contact investigations at 26 centers in 10 European countries including testing for latent infection with M. tuberculosis by the QuantiFERON-TB Gold In-Tube (QFT) test or the T-SPOT.TB (TSPOT) were prospectively collected and analyzed.
Among 5,020 contacts of 1,023 index cases, 25 prevalent secondary cases were identified at screening. Twenty-four incident cases occurred among 4,513 contacts during 12,326 years of cumulative follow-up. In those with a positive IGRA result, tuberculosis incidence was 0.2 (QFT) and 0 (TSPOT) per 100 patient-years when contacts received preventive chemotherapy versus 1.2 (QFT) and 0.8 (TSPOT) per 100 patient-years in those not treated (38 and 37 patients needed to be treated to prevent one case, respectively). Positive and negative predictive values were 1.9% (95% confidence interval CI, 1.1-3.0) and 99.9% (95% CI, 99.7-100) for the QFT and 0.7% (95% CI, 0.1-2.6) and 99.7% (95% CI, 99.1-99.9) for the TSPOT.
Tuberculosis rarely developed among contacts, and preventive chemotherapy effectively reduced the tuberculosis risk among IGRA-positive contacts. Although the negative predictive value of IGRAs is high, the risk for the development of tuberculosis is poorly predicted by these assays.
This work describes the synthesis and characterization of aromatic polyamides with iridium biscyclometalated units, together with the study of their physical and luminescent properties.
Display ...omitted
•Hybrid organic–inorganic polymers have been prepared.•The organic polymers have the structure of commercial aromatic polyamides (aramids).•The inorganic core is comprised by iridium(III) biscyclometalated units.•The hybrid aramids are endowed with outstanding thermal and mechanical properties.•The new hybrid polymers exhibit photoluminescence under UV irradiation.
This work describes the preparation of high-performance hybrid luminescent aramids (aromatic polyamides). The new hybrid aramids are based on the commercial MPIA (poly(m-phenylene isophthalamide) and possess structural units bearing iridium(III) fragments which are responsible for the luminescent behavior. The aramids were casted into films, which were studied as luminescent color converters (LUCOs). In parallel, to get insight into the structure-properties relationships, hybrid aramid model, i.e., monomeric iridium(III) complex that mimic the behavior of the polymers, was prepared and studied. The new hybrid aramids were analyzed as LUCO devices to test their performance. The monomeric Ir(III) complexes are luminescent, whereas all the films prepared also show reasonable luminescent properties for novel lab prepared high performance aramids with outstanding thermal and mechanical properties.
PDF
