Brief overview on bio-based adhesives and sealants

Adhesives and sealants (AS) are materials with excellent properties, versatility, and simple curing mechanisms, being widely used in different areas ranging from the construction to the medical sectors. Due to the fast-growing demand for petroleum-based products and the consequent negative environmental impact, there is an increasing need to develop novel and more sustainable sources to obtain raw materials (monomers). This reality is particularly relevant for AS industries, which are generally dependent on non-sustainable fossil raw materials. In this respect, biopolymers, such as cellulose, starch, lignin, or proteins, emerge as important alternatives. Nevertheless, substantial improvements and developments are still required in order to simplify the synthetic routes, as well as to improve the biopolymer stability and performance of these new bio-based AS formulations. This environmentally friendly strategy will hopefully lead to the future partial or even total replacement of non-renewable petroleum-based feedstock. In this brief overview, the general features of typical AS are reviewed and critically discussed regarding their drawbacks and advantages. Moreover, the challenges faced by novel and more ecological alternatives, in particular lignocellulose-based solutions, are highlighted.Funding Agency Portuguese Foundation for Science and Technology PTDC/AGR-TEC/4814/2014; PTDC/ASP-SIL/30619/2017; IF/01005/2014.info:eu-repo/semantics/publishedVersio

Measurement of the top-quark mass using a leptonic invariant mass in pp collisions at s√ = 13 TeV with the ATLAS detector

A measurement of the top-quark mass (mt) in the tt¯ → lepton + jets channel is presented, with an experimental technique which exploits semileptonic decays of b-hadrons produced in the top-quark decay chain. The distribution of the invariant mass mℓμ of the lepton, ℓ (with ℓ = e, μ), from the W-boson decay and the muon, μ, originating from the b-hadron decay is reconstructed, and a binned-template profile likelihood fit is performed to extract mt. The measurement is based on data corresponding to an integrated luminosity of 36.1 fb−1 of s√ = 13 TeV pp collisions provided by the Large Hadron Collider and recorded by the ATLAS detector. The measured value of the top-quark mass is mt = 174.41 ± 0.39 (stat.) ± 0.66 (syst.) ± 0.25 (recoil) GeV, where the third uncertainty arises from changing the PYTHIA8 parton shower gluon-recoil scheme, used in top-quark decays, to a recently developed setup

Suppression of back electron recombination on the photoanode-electrolyte interface with poly(4-vinylbenzoic acid) and poly(4-vinylpyridine) co-adsorbents for stable and efficient dye-sensitized solar cells

International audienceDye-sensitized solar cells (DSSC) are one of the most intensively developing PV technology to meet the emerging needs of wireless power for billions of IoT devices and wireless electronics; DSSCs have recently entered the indoor PV market. Suppressors of back electron recombination on the photoanode-electrolyte interface, also known as co-adsorbents, are key components of the DSSCs to obtain high power conversion efficiencies (PCE). Chenodeoxycholic acid (CDCA), yet obtained by extraction from the animal liver, dominates among other co-adsorbent and enables devices with the highest PCE and long lifetime. Achieving adequate PCE with long-term device stability with CDCA alternatives is a challenge addressed in this study using poly4-vinylbenzoic acid (PVBA) and poly(4-vinylpyridine) (P4VP). Polymeric co-adsorbents effectively suppress electron transfer from the TiO2/N719 photoanode to I3−/3I− electrolyte resulting in decently performing devices with 1-sun equivalent PCEs of 8.3 % and 9 %, respectively; 17.5 % and 22 % of artificial light PCEs were achieved. The presence of the polymer hampers molecular dye aggregation within the self-assembled monolayer; the acceleration of the charge injection and excited dye prolonging was monitored by Time-Correlated Single Photon Counting photoluminescence spectroscopy. Intrinsic device degradation in the accelerated light soaking test was assessed according to ISOS-L2 protocol. Carboxylic-functioned molecular chain of PVBA allows stronger adsorption on the photoanode-electrolyte interface and renderes stable devices with 1000 h of PCE history equivalent to conventional CDCA

Combination of Poly[(2-dimethylamino)ethyl methacrylate] and Poly(β-amino ester) Results in a Strong and Synergistic Transfection Activity

This work reports an innovative and very effective gene delivery nanosystem, based on the combination of poly­[(2-dimethylamino)­ethyl methacrylate] (PDMAEMA) and poly­(β-amino ester) (PβAE) homopolymers, that has the capacity to efficiently deliver genetic material into target cells, even in the presence of serum. The best formulation, prepared with the combination PDMAEMA/4PβAE at the 25/1 nitrogen/phosphate (N/P) ratio, presented a 700-fold and 220-fold higher transfection activity than that obtained with branched polyethylenimine (PEI)-based polyplexes and block copolymer-based polyplexes, respectively. This new nanocarrier revealed high transgene expression in different human cells, including hard-to-transfect normal human astrocytes. The polyplexes presented high protection of genetic material and reduced sizes, which are suitable physicochemical properties for in vivo applications. Overall, this study demonstrates that the combination of PDMAEMA and PβAE homopolymers resulted in a noticeable and synergistic effect in terms of transfection activity, without causing substantial toxicity, constituting a new platform for the development of gene delivery nanosystems

Characterization of suspension poly(vinyl chloride) resins and narrow polystyrene standards by size exclusion chromatography with multiple detectors: Online right angle laser-light scattering and differential viscometric detectors

This work reports the utilization of a multi-detector size chromatography for the characterization of poly(vinyl chloride) (PVC) resins prepared by suspension polymerization in the range of temperatures between 21 and 75 °C. The chromatography equipment offers the possibility of analyzing the samples in terms of their absolute molecular mass using a combination of three detectors (TriSEC): right angle light scattering (RALLS), a differential viscometer (DV) and refractive index (RI). The PVC resins were fully characterized concerning the molecular weight distribution (MWD), its dependence with intrinsic viscosity ([eta]) and molecular sizes (radius of gyration, Rg and hydrodynamic radius, Rh). Additionally, it is also presented the characterization of polystyrene narrow standards serving as reference polymers.http://www.sciencedirect.com/science/article/B6TWW-4HHGNVH-4/1/170871b80274a89470f2a790d3ed999

A seroepidemiological survey of Mycobacterium avium subsp. paratuberculosis in sheep from North of Portugal

The aim of this study was evaluate the risk factors for Mycobacterium avium subsp. paratuberculosis (Map) seroprevalence in sheep in the North of Portugal. The effects on seroprevalence of several variables such as individual characteristics, management practices, farm characteristics, animal health, and available veterinary services were evaluated. This information was then used in a multivariable logistic regression model in order to identify risk factors for Map seropositivity. Univariable analysis was used to screen the variables used in the logistic regression model. Variables that showed p values of <0.15 were retained for the multivariable analysis. Fifteen variables were associated with paratuberculosis in univariable analysis. The multivariable logistic regression model identified a number of variables as risk factors for seropositivity like sheep pure local and/or a cross of a local breed (OR=2.02), herd size with 31-60 head (OR=2.14), culling during the Spring-Summer season (OR=1.69) and the use of an anti-parasitic treatment such as Ivermectin as the only anti-parasitic medication (OR=5.60). Potential risk factors identified in this study support current recommendations for the control of paratuberculosis