RESUMENEl norte de la provincia de Neuquén (Depto. Pehuenches, Argentina) es muy poco conocido a nivel arqueológico, a pesar de estar ubicado en una posición central en relación con distintos temas clave del poblamiento humano de Sudamérica, incluyendo la extinción de la megafauna y sus causas, el poblamiento humano inicial y la existencia de discontinuidades arqueológicas en el Holoceno medio. En este trabajo se presenta el primer cuerpo de resultados paleoecológicos y arqueológicos para el sitio Cueva Huenul 1, recientemente excavado, que ofrece una secuencia sedimentaria que se extiende durante los últimos 16.000 años calendáricos. Estas evidencias incluyen el desarrollo de un marco crono-estratigráfico para el sitio, que aporta novedosa información tefro-cronológica. A partir de este análisis, se definen cuatro componentes temporales, sobre los cuales se asienta el estudio de los materiales recuperados: evidencias faunísticas (paleontológicas y arqueológicas), arqueobotánicas, líticas, cerámicas y de arte rupestre. Estos resultados en escala de sitio proveen una primera instancia de evaluación de procesos en escala macro-regional, así como las bases para la continuación de este proyecto.PALABRAS CLAVE: Neuquén, fauna extinta, poblamiento humano temprano, cronología, tendencias temporales. ARCHAEOLOGICAL PERSPECTIVES FOR NORTHERN PATAGONIA:CUEVA HUENUL 1 SITE (NEUQUEN PROVINCE, ARGENTINA) ABSTRACT Northern Neuquén Province (Pehuenches Dept., Argentina) is barely known from an archaeological 138 R. BARBERENA et al. perspective, though it is centrally placed in terms of several large-scale key issues in the peopling of South America: the extinction of the megafauna and its causes, early human presence, and the existence of archaeological discontinuities during the Mid-Holocene. In this paper we present the first body of paleoecological and archaeological data for Cueva Huenul 1 site, recently excavated, which offers a sedimentary sequence extending during the last of 16.000 calendar years. Initially, we present a chronostratigraphic frame for the site, including new tephro-chronological information. On this basis, four temporal components are defined, providing the historical scheme for the analysis of the recovered evidences that include: archaeofaunas (paleontological and archaeological), archaeobotany, lithic and ceramic technology, and rockart. These results at a site scale provide a first approach to a discussion of macro-regional processes, as well as the basis for the continuation of our research.KEY WORDS: Neuquén, extinct fauna, early human peopling, chronology, temporal tendencies. INTRODUCCIÓN Y ANTECEDENTESEste trabajo se enmarca en un proyecto arqueológico recientemente iniciado en el extremo noroeste de Patagonia (Departamento Pehuenches, provincia del Neuquén, Argentina; Fig. 1; Barberena, 2013). Básicamente la región carece de información arqueológica, lo que ofrece tanto una limitación como un desafío para el desarrollo de este proyecto. En esta instancia inicial de acercamiento a la arqueol...

Chitosan and chitosan oligomers are receiving increasing attention due to their antimicrobial properties. In the present study, they were assayed as a preventive treatment against white-rot decay of Populus wood (very important in economic and environmental terms), caused by Trametes versicolor fungus. Their capacity to incorporate different chemical species into the polymer structure with a view to improving their anti-fungal activity was also assessed by mixing oligo-chitosan with propolis and silver nanoparticles. The minimum inhibitory concentration of medium-molecular weight chitosan (MMWC), chitosan oligomers (CO), propolis (P), nanosilver (nAg), and their binary and ternary composites against T. versicolor was determined in vitro. Although all products exhibited anti-fungal properties, composites showed an enhanced effect as compared to the individual products: 100% mycelial growth inhibition was attained for concentrations of 2.0 and 0.2 mg·mL −1 for the CO-P binary mixture, respectively; and 2 µg·mL −1 for nAg in the ternary mixture. Subsequently, MMWC, CO, CO-P and CO-P-nAg composites were tested on poplar wood blocks as surface protectors. Wood decay caused by the fungus was monitored by microscopy and vibrational spectroscopy, evidencing the limitations of the CO-based coatings in comparison with MMWC, which has a higher viscosity and better adhesion properties. The usage of MMWC holds promise for poplar wood protection, with potential industrial applications. Coatings 2018, 8, 415 2 of 15its main characteristics, such as its bioactivity, non-toxicity or biodegradability, its antimicrobial effect is especially relevant [4][5][6]. Its activity against different fungi, gram positive and gram negative bacteria, is ascribed to the positive charge of amino group (NH 3 + ), which interacts electrostatically with the surface of the cellular membrane, destabilizing it. As a consequence, the presence of chitosan inside the cell can lead to intracellular responses such as inactivation or blocking of enzymes activities, and of DNA transcription and translation [7,8].The antifungal activity of chitosan not only depends on the fungus species, but also on its molecular weight (MW), polymerization degree (PD) or deacetylation degree (DD). For instance, chito-oligosaccharides with low MW, PD and DD have been reported to be more effective on phytopathogenic fungi than chitosan with higher MW, PD or DD [9][10][11].Another known advantage from chitosan and its oligomers is associated with their sorption and chelating properties. The cationic nature of the polymer allows it to bind to different chemicals species, ranging from organic macromolecules to metal nanoparticles [12][13][14]. Natural oils or extracts of natural products can be incorporated into the chitosan matrix, for example, by cross-linking, producing solutions, films or beads [15][16][17]. In the particular case of propolis, its polyphenols have been reported to form hydrogen bonds and covalent bonds with the functional groups in chitosan [18]. This results...

There is growing interest in the development of non-toxic, natural wood preservation agents to replace conventional chemicals. In this paper, the antifungal activities of silver nanoparticles, chitosan oligomers, and propolis ethanolic extract were evaluated against white-rot fungus Trametes versicolor (L.) Lloyd, with a view to protecting Populus spp. wood. In order to create a more realistic in-service type environment, the biocidal products were assessed according to EN:113 European standard, instead of using routine in vitro antimicrobial susceptibility testing methods. Wood blocks were impregnated with the aforementioned antifungal agents by the vacuum-pressure method in an autoclave, and their biodeterioration was monitored over 16 weeks. The results showed that treatments based on silver nanoparticles, at concentrations ranging from 5 to 20 ppm, presented high antifungal activity, protecting the wood from fungal attack over time, with weight losses in the range of 8.49% to 8.94% after 16 weeks, versus 24.79% weight loss in the control (untreated) samples. This was confirmed by SEM and optical microscopy images, which showed a noticeably higher cell wall degradation in control samples than in samples treated with silver nanoparticles. On the other hand, the efficacy of the treatments based on chitosan oligomers and propolis gradually decreased over time, which would be a limiting factor for their application as wood preservatives. The nanometal-based approach is thus posed as the preferred choice for the industrial treatment of poplar wood aimed at wood-based engineering products (plywood, laminated veneer lumber, cross-laminated timber, etc.).

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Grading tests were performed on 338 poplar wood samples (Populus × euramericana I-214) with dimensions of 150×50 mm2, 150×80 mm2, and 200×100 mm2 prepared for structural utilization. The non-destructive testing methods included ultrasound (Sylvatest) and induced vibrations (Portable Lumber Grader) combined with visual grading criteria. Additionally, screw withdrawal resistance was tested by the instrument Fakopp. These results were compared with those obtained by a four-point bending test according to the EN 408 (2004) standard. Ultrasound and induced vibrations overestimated the quality of this type of wood. Correlation equations are proposed to determine the true characteristics for each testing method. It can be concluded that poplar timber from clone I-214 has acceptable flexural strength, but a comparatively low elastic modulus, whereby it is not graded within a high strength class according to the EN 338 (2009) standard.