Effects of an innovative densification process on mechanical and physical properties of beech and Norway spruce veneers

AbstractIncreased wood density is obtained by compressing the wood porous structure under suitable moisture and temperature conditions to improve its physical, mechanical and color properties. A recently proposed wood densification method based on partial removal of lignin and hemicellulose in hot water solution of sodium hydroxide and sodium sulphite has shown promising results on solid wood. However, its applicability and effect on thin wood veneers have not been tested yet. In this study, the timing of the method has been adapted to estimate the densification treatment intensity dependence of wood properties (wood density and modulus of elasticity) and color change of softwood (Norway spruce) and hardwood (beech) veneers. Compared to control, density and rigidity increased, with improved wood properties peaking after only 90 s of treatment intensity. Furthermore, the color became darker after treatment compared to control, with no significant color difference between treatment intensities. In conclusion, densification of veneers, according to the presented adapted method, provides a significant improvement of veneers physical and mechanical properties, and produces color changes perceptible by the human eye. Our results can be further implemented and adapted to application in industrial plants, calling for new application of densified veneers.</jats:p

Short Communication: Driftwood provides reliable chronological markers in Arctic coastal deposits

Originating from the boreal forest and often transported over large distances, driftwood characterises many Arctic coastlines. Here we present a combined assessment of radiocarbon (14C) and dendrochronological (ring width) age estimates of driftwood samples to constrain the progradation of two Holocene beach-ridge systems near the Lena Delta in the Siberian Arctic (Laptev Sea). Our data show that the 14C ages obtained on syndepositional driftwood from beach deposits yield surprisingly coherent chronologies for the coastal evolution of the field sites. The dendrochronological analysis of wood from modern driftlines revealed the origin and recent delivery of the wood from the Lena River catchments. This finding suggests that the duration transport lies within the uncertainty of state-of-the-art 14C dating and thus substantiates the validity of age indication obtained from driftwood. This observation will help to better understand changes in similar coastal environments, and to improve our knowledge about the response of coastal systems to past climate and sea-level changes

Axial variation of xylem conduits in giant cacti

Giant columnar cacti store massive amounts of water in their parenchymous storage tissues in order to persist under conditions of extreme aridity. Nevertheless, the relationship between stem water storage capacity and the maximum efficiency to deliver water from the roots to stem storage tissues via xylem vessels remains largely unknown. Indeed, the relationship between the axial water flow in xylem and the lateral flow through the storage tissue may affect the xylem structure and, therefore, the plant water conduction strategies. Since the axial structure of vascular conduits has been demonstrated to be universal (i.e. in a broad spectrum of plant species xylem conduits widen basipetally at the same rate), we wanted to determine if both the vessel size and wall thickness in giant cactae follow the same general rule in spite of the buffer action of water storage tissue. To address these hypotheses, we are investigating anatomical variation in xylem structural traits and storage volume in the stems of giant cacti species belonging to different phylogenetic lineages that are native to both the Northern and Southern hemisphere (e.g.Pachycereus weberi, Echinopsis terschekii, Carnegiea gigantea). We collected cross-sections from 6 to 13 samples along the stem of each plant. We found that vessel lumina increased basipetally following a widening rate similar to what has been documented by the theoretical model (WBE model) and from existing surveys on a wide range of tree species. The conduits double wall thickness (t) and its span (s) ratio decrease basipetally and interplay to reduce the risk of cell collapse. We concluded that the xylem architecture of columnar cacti in this study was not influenced by the buffering action of the surrounding storage tissue, and that axial water transport efficiency is maintained for the length of the path as in many other plant species

PEG infiltration: an alternative method to obtain thin sections of cacti tissues

Abstract Exploring the anatomical variability along the stem of cacti requires obtaining high-quality thin sections from hard and soft tissues. Several embedding, infiltration, and sectioning methods have been applied mainly to investigate the harder stem base of cacti, where thin cross-sections are relatively easy to obtain. However, analyzing the variation of anatomical features along cacti stems remains a challenge. Specifically, at the tip of cacti stems, the soft and water-rich dominant tissues are difficult to infiltrate. Here we show results obtained by adapting polyethylene glycol (PEG) infiltration techniques and present a step-by-step description of a fast and hazardous chemical-free method that allows successful cross-sectioning. This infiltration technique may provide a tool to further explore and quantify xylem anatomical trait variation along stems of a wide range of succulent-stemmed taxa

Quantitative wood anatomy

Quantitative wood anatomy analyzes the variability of xylem anatomical features in trees, shrubs, and herbaceous species to address research questions related to plant functioning, growth, and environment. Among the more frequently considered anatomical features are lumen dimensions and wall thickness of conducting cells, fibers, and several ray properties. The structural properties of each xylem anatomical feature are mostly fixed once they are formed, and define to a large extent its functionality, including transport and storage of water, nutrients, sugars, and hormones, and providing mechanical support. The anatomical features can often be localized within an annual growth ring, which allows to establish intra-annual past and present structure-function relationships and its sensitivity to environmental variability. However, there are many methodological challenges to handle when aiming at producing (large) data sets of xylem anatomical data. Here we describe the different steps from wood sample collection to xylem anatomical data, provide guidance and identify pitfalls, and present different image-analysis tools for the quantification of anatomical features, in particular conducting cells. We show that each data production step from sample collection in the field, microslide preparation in the lab, image capturing through an optical microscope and image analysis with specific tools can readily introduce measurement errors between 5 and 30% and more, whereby the magnitude usually increases the smaller the anatomical features. Such measurement errors—if not avoided or corrected—may make it impossible to extract meaningful xylem anatomical data in light of the rather small range of variability in many anatomical features as observed, for example, within time series of individual plants. Following a rigid protocol and quality control as proposed in this paper is thus mandatory to use quantitative data of xylem anatomical features as a powerful source for many research topics

Plants in the UK flower a month earlier under recent warming.

Global temperatures are rising at an unprecedented rate, but environmental responses are often difficult to recognize and quantify. Long-term observations of plant phenology, the annually recurring sequence of plant developmental stages, can provide sensitive measures of climate change and important information for ecosystem services. Here, we present 419 354 recordings of the first flowering date from 406 plant species in the UK between 1753 and 2019 CE. Community-wide first flowering advanced by almost one month on average when comparing all observations before and after 1986 (p < 0.0001). The mean first flowering time is 6 days earlier in southern than northern sites, 5 days earlier under urban than rural settings, and 1 day earlier at lower than higher elevations. Compared to trees and shrubs, the largest lifeform-specific phenological shift of 32 days is found in herbs, which are generally characterized by fast turnover rates and potentially high levels of genetic adaptation. Correlated with January-April maximum temperatures at -0.81 from 1952-2019 (p < 0.0001), the observed trends (5.4 days per decade) and extremes (66 days between the earliest and latest annual mean) in the UK's first flowering dataset can affect the functioning and productivity of ecosystems and agriculture

Evaluation of the accuracy of image manipulation in the P3DentalTM software for guided implantodontic surgeries

Purpose: To collect and analyze data to determine the level of precision of the virtual values provided by P3DentalTM image manipulation software in comparison with real values measured using a digital pachymeter in polyurethane mandibles. Materials and methods: Five polyurethane mandibles were sectioned and drilled, providing a total of 120 samples for study, and then scanned with cone beam computed tomography. The images obtained were manipulated using the P3DentalTM software package and the resulting values were analyzed in comparison to the real values measured using a digital pachymeter with the aid of IBM® SPSS® database software. Results: Statistical analysis showed that there were significant differences (P = 0.01) between the virtual values measured using P3DentalTM software and the real values measured with the digital pachymeter, which had mean ± standard deviation of 8.15 ± 1.01mm and 7.89 ± 0.90mm respectively. Conclusions: In view of the statistically significant differences observed, dental surgeons should be aware that the guided surgery technique must be employed with care right from the outset since small errors of use are cumulative, increasing the likelihood of distortion between the ideal (virtual) and final (real) positions of the implants

Intra-annual density fluctuations (IADFs) in Pinus nigra (J. F. Arnold) at high-elevation in the central Apennines (Italy)

Abstract: Although wood anatomical features can provide yearly resolved climatic information at sub-seasonal resolution, the occurrence of intra-annual density fluctuations (IADFs) might be triggered by several abiotic factors under different ecological settings. Here, we use information on cambial age and tree-ring width to standardize the frequency of IADFs in European black pines from three different mountain slopes in the central Apennines (Italy). At each site, we sampled isolated 15–30-year pioneer pines above the forest limit, as well as close-grown 40–60-year planted pines at the forest limit. Mainly restricted to the latewood of both pioneer and planted trees, the occurrence of IADFs reveals a significant positive relationship with cambial age and ring width. Although the standardized IADFs are well synchronized between the planted and pioneer pines, the frequency of IADFs in narrow rings was higher in the pioneer pines. Drought conditions in July and August are responsible for the highest IADFs frequency in planted and pioneer pines, respectively. Our study underlines the value of IADFs to obtain a more nuanced understanding of the climatic drivers of wood formation at the intra-annual scale

Diagnóstico estructural de estructuras de madera históricas: La sala diplomática del Palacio Real de Nápoles

[EN] The aim of this article is to describe the diagnosis process made on the timber structure that holds up the vault of the Diplomatic Room of the Royal Palace in Naples (Italy). After a brief historical description of the Royal Palace and the Diplomatic Room, it discusses the methodology according to Italian regulations and the speci­fic problems that arose during the works. To complete the diagnosis, a dendrochronological analysis of the wooden elements was performed. The results show the residual mechanical properties of each structural element and the main problems to be resolved by the restorers. The dendrochronological conclusions yield that the dating of the elements is compatible with that of the frescoes on the vault and therefore demonstrate that the elements have not been replaced.[ES] El objetivo de este artículo es describir el proceso diagnóstico realizado en la estructura de madera que sostiene la bóveda de la Sala Diplomática del Palacio Real de Nápoles (Italia). Tras una breve descripción histórica del Palacio Real y la Sala Diplomática, se detalla la metodología conforme a la normativa italiana, y los problemas específicos que surgieron durante las operaciones. Para completar el diagnóstico, se realizó un análisis dendrocronológico de los elementos de madera. Los resultados muestran las propiedades mecánicas residuales de cada elemento estructural así como los principales problemas que deben ser resueltos por los restauradores. Las conclusiones dendrocronológicas muestran que la datación de los elementos de madera es compatible con la de los frescos de la bóveda y, por lo tanto, demuestra que los elementos no han sido reemplazados.Calicchio, D.; Bernabei, M.; Brunetti, M.; Crivellaro, A.; Macchioni, N.; Pollini, C. (2012). Diagnóstico estructural de estructuras de madera históricas: La sala diplomática del Palacio Real de Nápoles. Loggia, Arquitectura & Restauración. (24-25):112-121. doi:10.4995/loggia.2012.3007SWORD11212124-25BERNETTI, G.: Selvicoltura speciale, UTET, Torino, 1995.BONAMINI, G.; UZIELLI, L.; CECCOTTI, A.: "Sulla valutazione della resistenza meccanica del legno antico", en L'Edilizia, 1991, 5(12):771-777.BONAMINI, G.: "Restoring timber structures-Inspection and evaluation", en Lecture D3: Timber engineering STEP2 - Design - Details and structural systems, STEP/EUROFORTECH, Centrum Hout, The Netherlands, 1995, pp.D3/1-9.FONTI, P.; MACCHIONI, N.; THIBAUT, B.: "Ring shake in Chestnut (Castanea sativa Mill.): state of the art", en Annals of Forest Science, 2002, 59 (2): 129-139.MACCHIONI, N.: "Inspection techniques for ancient wooden structures", en Structural analysis of historical constructions II de ROCA, P.; GONZÁLES, J.L.; ONATE, E.; LOURENÇO, P.B. Editors, Cimne, 1998, pp. 149-162.MACCHIONI, N. & PIAZZA, M.: "Italian standardisation activity in the field of diagnosis and restoration of ancient timber structures", en Structural analysis of historical construction, de LOURENCO, P.B.; ROCA, P.; MODENA, C.; AGRAWAL, S.; Eds., New Dehli, 2006, pp. 395-404.PIOVESAN, G.; BERNABEI, M.; DI FILIPPO, A.; ROMAGNOLI, M.; SCHIRONE, B.: "A long-term tree ring beech chronology from a highelevation old-growth forest of Central Italy", en Dendrochronologia, 2003, 21(1): 13-22.SCHWEINGRUBER, F. H.: "Data archived at the World Data Center for Paleoclimatology Boulder Colorado USA", en http://www.ngdc.noaa.gov/paleo/ftp-treering.html, 1980.TAMPONE, G.; MANNUCCI, M.; MACCHIONI, N.: Strutture di legno. Cultura, conservazione e restauro, De Lettera, Milano, 2002.EN 334-1/2: Durability of wood and wood-based products. Definition of hazard classes of biological attack, General, 1993.UNI 11119: Cultural heritage - Wooden artefacts- Load-bearing structures - On site inspections for the diagnosis of timber members, UNI (Ente Nazionale Italiano di Unificazione), 2004