scholarly journals On the Experimental Assessment of the Molecular-Scale Interactions between Wood and Water

Forests ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 616 ◽  
Author(s):  
Nayomi Z. Plaza
Keyword(s):  
Cell Wall ◽  
State Of The Art ◽  
Bound Water ◽  
Local Environment ◽  
Polymer Dynamics ◽  
Experimental Assessment ◽  
Molecular Scale ◽  
Computational Work ◽  
Durable Products ◽  
Unmodified Wood

Although molecular-scale wood-water interactions needed for moisture-durability can lead to the accelerated development of moisture-durable products, these interactions are often experimentally elusive. In this perspective, the topic’s state of the art understanding will be discussed, excluding computational work. Recent research efforts based on infrared spectroscopy methods have provided new insights in terms of the accessibility of the wood polymers and moisture-induced polymer dynamics. Likewise, neutron scattering and nuclear magnetic relaxometry experiments have shown that bound water can be found within more than one local environment inside the cell wall. However, a majority of the experiments have focused on studying extracted or derived polymers instead of unmodified wood. Thus, in this paper some of the questions that still need to be addressed experimentally will also be highlighted.

scholarly journals Micromechanical properties of beech cell wall measured by micropillar compression test and nanoindentation mapping

Holzforschung ◽  
2020 ◽  
Vol 74 (9) ◽  
pp. 899-904
Author(s):  
Petr Klímek ◽  
Václav Sebera ◽  
Darius Tytko ◽  
Martin Brabec ◽  
Jaroslav Lukeš
Keyword(s):  
Cell Wall ◽  
Yield Stress ◽  
Compression Test ◽  
State Of The Art ◽  
Middle Lamella ◽  
Uniaxial Stress ◽  
Wood Structure ◽  
Micropillar Compression ◽  
The Mean ◽  
Insight Into

AbstractWood exhibits very different behavior and properties at different scales. One important scale is the cell wall (CW) that is commonly tested by nanoindentation. Common nanoindentation provides important insight into the material but has limitations because it does not apply uniaxial stress and provides data from single spots. Therefore, the aim was to examine beech CW using two state-of-the-art techniques: micropillar compression (MCo) and nanoindentation mapping (NIP). The mean strength of the beech CW was found to be about 276 MPa and the mean yield stress was 183 MPa. These values were higher than those in most cited literature, which was attributed to the fact that libriform fibers from beech late wood were measured. Mean E obtained from MCo was about 7.95 GPa, which was lower than the values obtained on a macrolevel and about 61% of the value obtained from NIP. NIP also showed that E of the CW around the middle lamella (ML) was about 64% of the value at the location attributed to the S2 layer. Lower E from MCo may be caused by sinking of the micropillar into the wood structure under the load. Failure of the micropillars showed gradual collapse into themselves, with debonding at the S3 layer or the MLs.

Moisture-dependent orthotropic viscoelastic properties of Chinese fir wood during quenching in the temperature range of 20 to −120°C

Holzforschung ◽  
2019 ◽  
Vol 74 (1) ◽  
pp. 10-19 ◽  
Author(s):  
Zhu Li ◽  
Jiali Jiang ◽  
Jianxiong Lyu
Keyword(s):  
Cell Wall ◽  
Viscoelastic Properties ◽  
Wood Cell Wall ◽  
Bound Water ◽  
Free Water ◽  
Chinese Fir ◽  
High Temperature Side ◽  
Temperature Spectrum ◽  
Β Relaxation ◽  
Temperature Side

AbstractAn understanding of wood’s moisture-dependent viscoelastic properties under various temperature conditions is important for assessing its utilization and product quality. In this study, we investigated the influence of moisture content (MC) on the orthotropic viscoelasticity of Chinese fir wood (Cunninghamia lanceolata [Lamb.] Hook.) during quenching ranging from 20 to −120°C. The storage modulus (E′) and loss factor (tan δ) of the longitudinal (L), radial (R) and tangential (T) specimens were determined for nine MC levels ranging from 0.6 to 60.0%. The results showed that E′ generally decreased with increasing amount of bound water in all orthotropic directions, regardless of the temperature. In contrast, a sharp increase in E′ was observed at temperatures below 0°C when free water was present, due to the formation of ice within the cell lumens. The γ-relaxation and β-relaxation were observed in the temperature spectrum. A comparison demonstrates that the β-relaxation showed evident grain orientation. When only bound water was present in the wood cell wall, one clear γ-relaxation was found for all orthotropic directions. In contrast, only the high-temperature side of the γ-relaxation was observed in the three anatomic directions in specimens with free water, which might be related to the amorphous wood cell wall coupling with the frozen free water during the quenching process. In addition, the differences in peak temperatures of the γ-relaxation among the three main directions diminished with increasing bound water.

A multinuclear magnetic resonance imaging (MRI) study of wood with adsorbed water: Estimating bound water concentration and local wood density

Holzforschung ◽  
2011 ◽  
Vol 65 (1) ◽  
pp. 103-107 ◽  
Author(s):  
Sergey V. Dvinskikh ◽  
Marielle Henriksson ◽  
Lars A. Berglund ◽  
István Furó
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cell Wall ◽  
Magnetic Resonance ◽  
Bound Water ◽  
Water Concentration ◽  
Adsorbed Water ◽  
Resonance Imaging ◽  
Wood Tissue ◽  
Cell Wall Polymers ◽  
Magnetic Resonance Imaging Mri

Abstract The interaction between moisture and the macromolecular wood tissue is of critical importance to wood properties. In this context, magnetic resonance imaging (MRI) is very promising as this method could deliver molecular information on the submillimeter scale (i.e., along concentration gradients) about both free and adsorbed water and the cell wall polymers. In the present study, it is demonstrated for the first time that wood containing adsorbed heavy water (2H2O) can be studied by MRI based on separated images due to water (2H MRI) and cell wall polymers (1H MRI). Data confirm that in specimens equilibrated at controlled humidity there is a direct correlation between bound water content and relative density of the polymers in wood tissue; there is a strong variation across annual rings.

scholarly journals Species-Habitat Associations: Spatial data, predictive models, and ecological insights

2020 ◽  
Author(s):  
Jason Matthiopoulos ◽  
John Fieberg ◽  
Geert Aarts
Keyword(s):  
Spatial Data ◽  
State Of The Art ◽  
Anthropogenic Impacts ◽  
Local Environment ◽  
Statistical Technique ◽  
Habitat Associations ◽  
New Methods ◽  
Spatiotemporal Scales ◽  
Ecological Mechanisms ◽  
Living Organisms

Ecologists develop species-habitat association (SHA) models to understand where species occur, why they are there and where else they might be. This knowledge can be used to designate protected areas, estimate anthropogenic impacts on living organisms and assess risks from invasive species or disease spill-over from wildlife to humans. Here, we describe the state of the art in SHA models, looking beyond the apparent correlations between the positions of organisms and their local environment. We highlight the importance of ecological mechanisms, synthesize diverse modelling frameworks and motivate the development of new analytical methods. Above all, we aim to be synthetic, bringing together several of the apparently disconnected pieces of ecological theory, taxonomy, spatiotemporal scales, and mathematical and statistical technique in our field. The first edition of this ebook reviews the ecology of species-habitat associations, the mechanistic interpretation of existing empirical models and their shared statistical foundations that can help us draw scientific insights from field data. It will be of interest to graduate students and professionals looking for an introduction to the ecological and statistical literature of SHAs, practitioners seeking to analyse their data on animal movements or species distributions and quantitative ecologists looking to contribute new methods addressing the limitations of the current incarnations of SHA models.

scholarly journals A Review on Microorganisms-Derived Products as Potential Antimicrobial Agents

2021 ◽  
Author(s):  
Alka Rani ◽  
Khem Chand Saini ◽  
Felix Bast ◽  
Sunita Varjani ◽  
Sanjeet Mehariya ◽  
...  
Keyword(s):  
Cell Wall ◽  
Antimicrobial Peptides ◽  
Bioactive Compounds ◽  
Mode Of Action ◽  
Antimicrobial Agents ◽  
State Of The Art ◽  
Drug Resistant ◽  
Fungal Cell ◽  
Glucan Synthase ◽  
Streptomyces Sp

Microorganisms including actinomycetes, archaea, bacteria, fungi, yeast, and micro algae are the auspicious source of vital bioactive compounds. In this review, the existing state of the art re-garding antimicrobial molecules from microorganisms has been summarized. The potential an-timicrobial compounds from actinomycetes, particularly Streptomyces sp.; archaea; fungi including endophytic and marine-derived fungi, mushroom; yeast, and microalgae were briefly described. Furthermore, this review briefly summarized the activity and mode of action of bacteriocins, a ribosomally synthesized antimicrobial peptides product of Eurotium sp., Streptomyces parvulus, S. thermophiles, Lactococcus lactis, etc. Bacteriocins have inherent properties such as targeting multi-ple-drug resistant pathogens, which allows them to be considered next-generation antibiotics. Similarly, Glarea lozoyensis derived antifungal lipohexpeptides i.e., pneumocandins, inhibits 1,3-β-glucan synthase of the fungal cell wall and acts as a precursor for the synthesis of caspo-fungin, is also elaborated. In conclusion, this review highlights the possibility of using microor-ganisms as an antimicrobial resource for biotechnological, nutraceutical, and pharmaceutical ap-plications. However, more investigations are still required to separate, purify, and characterize these bioactive compounds and transfer these primary drugs into clinically approved antibiotics.

scholarly journals Effects of Moisture on Diffusion in Unmodified Wood Cell Walls: A Phenomenological Polymer Science Approach

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1084 ◽  
Author(s):  
Joseph E. Jakes ◽  
Christopher G. Hunt ◽  
Samuel L. Zelinka ◽  
Peter N. Ciesielski ◽  
Nayomi Z. Plaza
Keyword(s):  
Cell Wall ◽  
Polymer Matrix ◽  
Cell Walls ◽  
Glassy State ◽  
Solid Polymer ◽  
Future Research ◽  
Polymer Science ◽  
Glass Transitions ◽  
The Hierarchical Structure ◽  
Unmodified Wood

Despite the importance of cell wall diffusion to nearly all aspects of wood utilization, diffusion mechanisms and the detailed effects of moisture remain poorly understood. In this perspective, we introduce and employ approaches established in polymer science to develop a phenomenological framework for understanding the effects of moisture on diffusion in unmodified wood cell walls. The premise for applying this polymer-science-based approach to wood is that wood polymers (cellulose, hemicelluloses, and lignin) behave like typical solid polymers. Therefore, the movement of chemicals through wood cell walls is a diffusion process through a solid polymer, which is in contrast to previous assertions that transport of some chemicals occurs via aqueous pathways in the cell wall layers. Diffusion in polymers depends on the interrelations between free volume in the polymer matrix, molecular motions of the polymer, diffusant dimensions, and solubility of the diffusant in the polymer matrix. Because diffusion strongly depends on whether a polymer is in a rigid glassy state or soft rubbery state, it is important to understand glass transitions in the amorphous wood polymers. Through a review and analysis of available literature, we conclude that in wood both lignin and the amorphous polysaccharides very likely have glass transitions. After developing and presenting this polymer-science-based perspective of diffusion through unmodified wood cell walls, suggested directions for future research are discussed. A key consideration is that a large difference between diffusion through wood polymers and typical polymers is the high swelling pressures that can develop in unmodified wood cell walls. This pressure likely arises from the hierarchical structure of wood and should be taken into consideration in the development of predictive models for diffusion in unmodified wood cell walls.

On the Evolution of Energy Dissipation Devices for Seismic Design

2002 ◽  
Vol 18 (2) ◽  
pp. 309-346 ◽  
Author(s):  
Juan Enrique Martínez-Rueda
Keyword(s):  
Energy Dissipation ◽  
Nonlinear Analysis ◽  
Seismic Design ◽  
Historical Perspective ◽  
State Of The Art ◽  
Original Research ◽  
Experimental Assessment ◽  
Analysis Techniques ◽  
The Subject ◽  
Energy Dissipation Devices

A review of the evolution of energy dissipation devices of hysteretic type is presented. Both friction and yielding devices are included in the paper covering a worldwide range of applications. Due to the increasingly large number of available devices, the paper does not attempt to present a state-of-the-art on the subject, but to focus on discussing the main original research efforts that have paved the way of the current technology of energy dissipation devices. Relevant past applications of devices are briefly described making particular emphasis on important issues such as experimental assessment, effectiveness of their modeling by nonlinear analysis techniques, materials and constructability. Devices selected for discussion in the paper are presented in a historical perspective and are considered pioneer original steps or research efforts directed towards an efficient and rational use of energy dissipation technology.

scholarly journals The Study of Bound Water Status and Pore Size Distribution of Chinese Fir and Poplar Cell Wall by Low-Field NMR

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Huimin Cao ◽  
Jianxiong Lyu ◽  
Yongdong Zhou ◽  
Xin Gao
Keyword(s):  
Cell Wall ◽  
Low Temperature ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Adsorption Isotherms ◽  
Bound Water ◽  
Chinese Fir ◽  
Fast Growing ◽  
Pore Size Distributions

With the increasing shortage of timber resources and the advancement of environmental protection projects, many artificial fast-growing forests are planted and used as raw materials in China. There are significant differences in the properties of natural forest wood and artificial fast-growing forest wood, and the properties of wood mainly depend on the change in the status of bound water in the cell wall. In this study, the fiber saturation point (FSP) and pore size distributions within the cell wall of six species of fast-growing forest wood were studied by low-temperature nuclear magnetic resonance (NMR) technology. The effects of species, growth rings, and extractives on the FSP and pore structure were analyzed. The water vapor sorption experiments were performed, and the adsorption isotherms of the samples were fitted through the Guggenheim-Anderson-de Boer (GAB) equation. According to the least-square regression of the adsorption isotherms and combined with the low-temperature NMR experiments, the content and proportion of the different types of bound water were analyzed. The results showed that the average FSP of each Chinese fir was about 40% and that of each poplar was about 35%. There is about a 10% difference between the FSP measured by NMR technology and the adsorption bound water content obtained by adsorption isothermal. The pore size distribution results show that in all samples, the proportion of pores larger than 10.5 nm is very low, about 10%; the proportion of 1.92-10.5 nm pores is about 30%; and the proportion of pores smaller than 1.92nm is more than 50%. This work will be helpful to the study of the wood moisture status and provide reference data for wood modification.

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