Controlling Cell Behavior Through the Design of Polymer Surfaces

Polymers have gained a remarkable place in the biomedical field as materials for the fabrication of various devices and for tissue engineering applications. The initial acceptance or rejection of an implantable device is dictated by the crosstalk of the material surface with the bioentities present in the physiological environment. Advances in microfabrication and nanotechnology offer new tools to investigate the complex signaling cascade induced by the components of the extracellular matrix and consequently allow cellular responses to be tailored through the mimicking of some elements of the signaling paths. Patterning methods and selective chemical modification schemes at different length scales can provide biocompatible surfaces that control cellular interactions on the micrometer and sub‐micrometer scales on which cells are organized. In this review, the potential of chemically and topographically structured micro‐ and nanopolymer surfaces are discussed in hopes of a better understanding of cell–biomaterial interactions, including the recent use of biomimetic approaches or stimuli‐responsive macromolecules. Additionally, the focus will be on how the knowledge obtained using these surfaces can be incorporated to design biocompatible materials for various biomedical applications, such as tissue engineering, implants, cell‐based biosensors, diagnostic systems, and basic cell biology. The review focusses on the research carried out during the last decade.     

The economics of the CDM levy: Revenue potential,tax incidence and distortionary effects

A levy on the Clean Development Mechanism and other carbon trading schemes is a potential source of finance for climate change adaptation. An adaptation levy of 2% is currently imposed on all CDM transactions which could raise around $500 million between now and 2012. This paper analyses the scope for raising further adaptation finance from the CDM, the economic costs (deadweight loss) of such a measure and the incidence of the levy, that is, the economic burden the levy would impose on the buyers and sellers of credits. We find that a levy of 2% could raise up to $2 billion a year in 2020 if there are no restrictions on demand. This could rise to $10 billion for a 10% tax. Restrictions on credit demand (called supplementarity limits, the requirement that most emission abatement should happen domestically) curtail trade volumes and consequently tax revenues. They also alter the economic impact of the CDM levy. Without supplementarity restrictions sellers (developing countries) bear two-thirds of the cost of the tax. If there are supplementarity limits they can pass on the tax burden to buyers (developed countries) more or less in full. Without supplementarity restrictions the distortionary effect of the levy (its deadweight loss) rises sharply with the tax rate. With them the deadweight loss is close to zero.     

Identification of Fiber Breakage in Fiber Reinforced Plastic by Low-Amplitude Filtering of Acoustic Emission Data

A new low-amplitude filtering technique has been developed for the identification of fiber breakage in fiber reinforced plastics from acoustic emission data. In this approach, the acoustic emission hits associated with fiber breakage are separated from the hits associated with other failure mechanisms by filtering out the low amplitude hits from the measured data. The lowest remaining amplitude upon the cumulative plot of the remaining hits vs. load coinciding with the cumulative signal strength vs. load plot is taken as the borderline between fiber breakage hits and non-fiber breakage hits. Experiments were conducted on unidirectional-fiber specimens and complex-fiber specimens to examine the efficacy of the proposed technique. Evaluation of the experimental results by visual inspection and extensive scanning electron microscope studies verifies the low-amplitude filtering technique as a reliable tool for identifying fiber breakage in fiber reinforced plastics.     

Lipase/acyltransferase‐catalysed interesterification of fat blends containing n‐3 polyunsaturated fatty acids

The lipase/acyltransferase from Candida parapsilosis is an original biocatalyst that preferentially catalyses alcoholysis over hydrolysis in biphasic aqueous/organic media. In this study, the performance of the immobilised biocatalyst in the interesterification in solvent‐free media of fat blends rich in n‐3 polyunsaturated fatty acids (n‐3 PUFA) was investigated. The interesterification activity of this biocatalyst at a water activity (a_w) of 0.97 was similar to that of commercial immobilised lipases at a_w values lower than 0.5. Thus, the biocatalyst was further used at an a_w of 0.97. Response surface modelling of interesterification was carried out as a function of medium formulation, reaction temperature (55–75 °C) and time (30–120 min). Reaction media were blends of palm stearin (PS), palm kernel oil and triacylglycerols (TAG) rich in n‐3 PUFA (“EPAX 4510TG”; EPAX AS, Norway). The best results in terms of decrease in solid fat content were observed for longer reaction time (>80 min), lower temperature (55–65 °C), higher “EPAX 4510TG” content and lower PS concentration. Reactions at higher temperature led to final interesterified fat blends with lower free fatty acid contents. TAG with high equivalent carbon number (ECN) were consumed while acylglycerols of lower ECN were produced.     

Octanitrocubane: A New Nitrocarbon

Octanitrocubane, the first new nitrocarbon in 18 years, is introduced as a potential explosive of great power. Its synthesis and characterization are described.     

Antimicrobial action and clotting time of thin,hydrated poly(vinyl alcohol)/cellulose acetate films functionalized with LL37 for prospective wound-healing applications

Poly(vinyl alcohol)/cellulose acetate (PVA/CA) films were prepared via a new method that combines principles from solvent casting and phase inversion. To guarantee some degree of flexibility, films were produced with a higher percentage of PVA compared to CA, from 90/10 to 50/50. The antimicrobial peptide (AMP) LL37 was then anchored using dopamine as a binding agent. Films were characterized in terms of functional groups, thermal stability, tensile strength, porosity, swelling, and degradation (stability in physiological media at different pHs). The antimicrobial performance of LL37 surface-modified films was tested against Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli in dynamic environment and in the presence and absence of an albumin interface. LL37 treated films demonstrated great antibacterial efficacy against the three kinds of bacteria, ≈75% inhibition for S. aureus, ≈85% for S. epidermidis, and ≈60% for E. coli, regardless of PVA/CA ratio. Presence of albumin reduced bacteria inhibition in all tested groups, most likely due to the binding of the protein molecules to the antimicrobial agents, reducing the free fraction available for bacterial killing. Films treated with LL37 accelerated clotting time (≈10 min) above vancomycin and bare surfaces, demonstrating great capacity to activate the intrinsic coagulation cascade. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48626.     

Extraction of Mentha spicata L. Volatile Compounds: Evaluation of Process Parameters and Extract Composition

Mint (Mentha spicata L.) is a European aromatic plant, with its essential oil used in food, pharmaceutical and cosmetic industries. Supercritical fluid extraction (SFE) is important for natural products, because it is residue free and preserves thermolabile compounds and product characteristics. The aim of this work was to obtain mint essential oil by sub-/supercritical extraction, with and without modifier and in different operational conditions, by hydro-distillation and by Soxhlet with different solvents. The results indicated the SFE highest yield (2.38% w/w) was obtained at 50 °C and 300 bar, with the crossover of yield isotherms occurring between 140 and 170 bar. When using a cosolvent for SFE, the ethanol showed the highest yield, compared to ethyl acetate. The mint essential oil was rich in compounds with therapeutic activities and several substances of industrial interest, such as carvone, cineol, and pulegone, presenting also good antioxidant activity performance.     

Synthesis and Characterization of Novel Polyol Esters of Undecylenic Acid As Ecofriendly Lubricants

Three novel esters of undecylenic acid (UA) were synthesized using the following polyols: linear diglycerol (DG), pentaerythritol monomethylether (PEME), and trimethyloltoluene (TMT). They were characterized through density, viscosity, thermo-oxidative stability, melting point (m.p.), miscibility with mineral oils, and toxicity to evaluate their potential as ecofriendly lubricants. Trimethylolpropane (TMP) triundecylenate was also synthesized and characterized as a reference ester. Esters’ densities were in the range 0.93–0.97 g cm⁻³. The PEME ester showed a kinematic viscosity of 25.2 cSt at 40°C, only slightly higher than that of TMP ester (24.7 cSt), both of them near the ISO VG 22 class, while DG and TMT esters were near the ISO VG 32 class, with viscosities of 28.3 and 37.1 cSt, respectively. PEME and TMT esters were similar in thermo-oxidative stability and more stable than their corresponding oleate esters. The m.p. of TMT ester was remarkedly low (−54°C), showing its potential for very cold temperature applications. TMT ester was found to be nontoxic against Artemia salina (LC₅₀ > 1000 μg mL⁻¹), an initial indication of nontoxicity of UA esters in aquatic media. The synthesized esters showed potential to be applied as ecofriendly lubricants.