scholarly journals FTIR analysis of chemical changes in wood induced by steaming and longitudinal compression

Cellulose ◽  
2020 ◽  
Vol 27 (12) ◽  
pp. 6811-6829 ◽  
Author(s):  
Mátyás Báder ◽  
Róbert Németh ◽  
Jakub Sandak ◽  
Anna Sandak
Keyword(s):  
Functional Groups ◽  
Cell Walls ◽  
Beech Wood ◽  
Industrial Applications ◽  
Structural Elements ◽  
Longitudinal Compression ◽  
Chemical Mechanisms ◽  
Modification Process ◽  
Physical Chemical ◽  
Detailed Interpretation

Abstract Pleating is an optimal way to increase bendability of wood used in diverse industrial applications. It results in the excessive buckling of cell walls and modifications of constitutive polymers. However, thoughtful understanding of the physical–chemical mechanisms of that modification process is very limited. The main purpose of the present study was to identify changes in functional groups of wood polymers induced by longitudinal compression. Four types of wood samples prepared from beech and sessile oak (untreated, steamed, longitudinally compressed and fixated for 1 min as well as longitudinally compressed and fixated for 18 h) were assessed by infrared spectroscopy. The spectra interpretation revealed that changes can be observed in hydroxyl as well as in carbon–oxygen single and carbon-hydrogen functional groups of polysaccharides and lignin. Beech wood seems to be more susceptible to investigated modification processes as compared to oak. Detailed interpretation of infrared spectra allows identification of changes in the hygroscopicity of wood as well as alterations in the linkage between structural elements in the polymer matrix of wood induced by the applied treatments. Graphic Abstract

scholarly journals Thermal degradation of hemicellulose and cellulose in ball-milled cedar and beech wood

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Jiawei Wang ◽  
Eiji Minami ◽  
Mohd Asmadi ◽  
Haruo Kawamoto
Keyword(s):  
Thermal Degradation ◽  
Ball Milling ◽  
Cell Walls ◽  
Uronic Acid ◽  
Beech Wood ◽  
Cellulose Microfibrils ◽  
Homogeneous Distribution ◽  
Japanese Beech ◽  
Temperature Range ◽  
The Matrix

AbstractThe thermal degradation reactivities of hemicellulose and cellulose in wood cell walls are significantly different from the thermal degradation behavior of the respective isolated components. Furthermore, the degradation of Japanese cedar (Cryptomeria japonica, a softwood) is distinct from that of Japanese beech (Fagus crenata, a hardwood). Lignin and uronic acid are believed to play crucial roles in governing this behavior. In this study, the effects of ball milling for various durations of time on the degradation reactivities of cedar and beech woods were evaluated based on the recovery rates of hydrolyzable sugars from pyrolyzed wood samples. The applied ball-milling treatment cleaved the lignin β-ether bonds and reduced the crystallinity of cellulose, as determined by X-ray diffraction. Both xylan and glucomannan degraded in a similar temperature range, although the isolated components exhibited different reactivities because of the catalytic effect of uronic acid bound to the xylose chains. These observations can be explained by the more homogeneous distribution of uronic acid in the matrix of cell walls as a result of ball milling. As observed for holocelluloses, cellulose in the ball-milled woods degraded in two temperature ranges (below 320 °C and above); a significant amount of cellulose degraded in the lower temperature range, which significantly changed the shapes of the thermogravimetric curves. This report compares the results obtained for cedar and beech woods, and discusses them in terms of the thermal degradation of the matrix and cellulose microfibrils in wood cell walls and role of lignin. Such information is crucial for understanding the pyrolysis and heat treatment of wood.

Extraction and analysis of polysaccharides from tissues of Retama monosperma branches

2020 ◽  
Vol 9 (5) ◽  
pp. 214-221
Author(s):  
H. Bokhari-Taieb Brahimi ◽  
D. E. Aizi ◽  
A. Bouhafsoun ◽  
K. Hachem ◽  
R. Mezemaze ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Biochemical Analysis ◽  
Colorimetric Assay ◽  
Structural Characteristics ◽  
Water Extract ◽  
Uronic Acids ◽  
Symbiotic Associations ◽  
Physical Chemical ◽  
Retama Monosperma

Retama monosperma is a fabaceous shrub that colonizes dune sands owing to its particularly important root system at depth and on the surface. It establishes symbiotic associations with rhizobia and thus plays a role in the bio -fertilization of soils. The stem fibers of R. monosperma are an interesting material for industry because of their useful biometric, physical, chemical and structural characteristics. The aim of this study was to complete these data with a biochemical analysis of the cell walls tissues of adult branches of R. monosperma. Cellulose, hemicelluloses and pectins were extracted from cell wall. The weight dosage indicated that cellulose remained the major component of the wall (56% from the crude cell wall and 52% from the delignified cell wall) ahead of hemicelluloses (16% from the crude cell wall and 14% from the delignified cell wall) and pectins (5.6% from the crude cell wall and 5% from the delignified cell wall for water extract pectins and 3% from the crude cell wall and 2.4% from the delignified cell wall for oxalate extract pectins). The colorimetric assay of pectins extracted from lignified cell wall of R. monosperma suggested presence of more uronic acids (14.95µg/mL) than pectins extracted from a delignified cell wall (12.37 µg/mL). Gas chromatographic analysis of hemicellulosic extracts showed the presence of xylose as the major ose (54.7% from the crude cell wall and 46.7% from the delignified cell wall). Pectins were represented by homogalacturonan chains and rhamnogalacturonans 1. Data generated in this study are helpful for valorization of this plant.

scholarly journals Myelin can't change the basic mechanisms of axonal conduction

2017 ◽  
Author(s):  
Alessandro M Morelli ◽  
Isabella Panfoli
Keyword(s):  
Neuronal Activity ◽  
Nerve Conduction ◽  
Conduction Mechanism ◽  
Chemical Mechanisms ◽  
Axonal Conduction ◽  
Physical Chemical ◽  
Myelinated Nerves ◽  
New Hypothesis ◽  
Precise Role

We propose a new hypothesis about the physical-chemical mechanisms of nerve conduction in myelinated nerves, tending to bridge the theoretical gap existing to date between the basic neuronal activity and its adaptation to myelination. All the considerations imply a simplification of the underlying theories, identifying a precise role for myelin. The ATP-supplying energetic role for myelin allows to overcome the theories that have not yet found a physical-chemical solid confirmation. A radical simplification of nerve conduction mechanism is envisaged: it can be supposed that this mechanism remains unaltered in the passage from the unmyelinated to the myelinated conditions.

Microwave Treatment of Hazardous Wastes: Physical Chemical Mechanisms

1992 ◽  
Vol 269 ◽  
Author(s):  
Leonard Dauerman ◽  
Gabriele Windgasse ◽  
Naihong Zhu ◽  
Yaoll He
Keyword(s):  
Field Testing ◽  
Microwave Treatment ◽  
Toxic Heavy Metals ◽  
Waste Streams ◽  
Major Drawback ◽  
Power Cost ◽  
Chemical Mechanisms ◽  
Physical Chemical ◽  
Site Field ◽  
Power Costs

ABSTRACTThe objective Is to develop processes to treat hazardous waste streams using microwave treatment. First, physical chemical mechanisms have been posited for a variety, of such waste streams including: soils contaminated with organics, and toxic heavy metals; “spent” GAC; organics in the gas phase. Second, feasibility tests are being carried out to determine if on-site field testing is warranted. In the case of microwave-induced steam distillation of volatile and semivolatile organics, pilot plant stuides indicate that the incident power cost is not prohibitive: that fear of prohibitive power costs has been thought to be the major drawback for micrwave treatment to become a competitive technology in this market.

scholarly journals Review on nanoparticles and nanostructured materials: history, sources, toxicity and regulations

2018 ◽  
Vol 9 ◽  
pp. 1050-1074 ◽  
Author(s):  
Jaison Jeevanandam ◽  
Ahmed Barhoum ◽  
Yen S Chan ◽  
Alain Dufresne ◽  
Michael K Danquah
Keyword(s):  
Risk Assessment ◽  
Nanostructured Materials ◽  
Mammalian Cells ◽  
Size Composition ◽  
Biological Properties ◽  
Industrial Applications ◽  
Specific Knowledge ◽  
Naturally Occurring ◽  
Physical Chemical ◽  
Toxic Reactions

Nanomaterials (NMs) have gained prominence in technological advancements due to their tunable physical, chemical and biological properties with enhanced performance over their bulk counterparts. NMs are categorized depending on their size, composition, shape, and origin. The ability to predict the unique properties of NMs increases the value of each classification. Due to increased growth of production of NMs and their industrial applications, issues relating to toxicity are inevitable. The aim of this review is to compare synthetic (engineered) and naturally occurring nanoparticles (NPs) and nanostructured materials (NSMs) to identify their nanoscale properties and to define the specific knowledge gaps related to the risk assessment of NPs and NSMs in the environment. The review presents an overview of the history and classifications of NMs and gives an overview of the various sources of NPs and NSMs, from natural to synthetic, and their toxic effects towards mammalian cells and tissue. Additionally, the types of toxic reactions associated with NPs and NSMs and the regulations implemented by different countries to reduce the associated risks are also discussed.

Bottom-up and top-down effects on phytoplankton functional groups in Hulun Lake, China

2021 ◽  
Vol 57 ◽  
pp. 3
Author(s):  
Chengxue Ma ◽  
Chang Zhao ◽  
Patteson Chula Mwagona ◽  
Ziyu Li ◽  
Zixuan Liu ◽  
...  
Keyword(s):  
Functional Groups ◽  
Phytoplankton Biomass ◽  
Eutrophic Lake ◽  
Positive Influence ◽  
Freshwater Ecosystems ◽  
Top Down ◽  
Bottom Up ◽  
Physical Chemical ◽  
Phytoplankton Functional Groups ◽  
Negative Effect

The debates about the extent to which phytoplankton in freshwater ecosystems are regulated by top-down or bottom-up forces have been ongoing for decades. This study examines the effects of bottom-up and top-down factors on the phytoplankton functional groups in a eutrophic lake. Phytoplankton and zooplankton were sampled and physical-chemical variables measured from May 2019 to October 2019 in Lake Hulun, China. Approximately 43 phytoplankton species were observed and grouped into 23 functional groups. For the zooplankton, about 27 species were observed and classified into 8 functional groups. The study revealed that the bottom-up effects of physical-chemical variables on some phytoplankton functional groups was stronger than the top-down effects of zooplankton. Water temperature (WT), total phosphorus (TP), total nitrogen (TN), conductivity (Cond), water transparency (SD), and dissolved oxygen (DO) significant influence the biomass of the phytoplankton functional groups. The biomass of phytoplankton functional groups was influenced positively by nutrient availability likely because nutrients influence the growth and reproduction of phytoplankton in freshwater. WT and DO had a positive influence on biomass of phytoplankton functional groups. Conversely, phytoplankton biomass revealed a decreasing trend when SD and Cond significantly increased. This study showed that zooplankton functional groups were positively correlated with phytoplankton biomass implying that the top-down control of phytoplankton by the zooplankton in the lake is not strong enough to produce a negative effect. It is evident that the zooplankton functional groups in Lake Hulun are controlled more by bottom-up force than top-down.

Prediction of physical properties of thermosetting resin by using machine learning and structural formulas of raw materials

MRS Advances ◽  
2020 ◽  
Vol 5 (29-30) ◽  
pp. 1567-1575
Author(s):  
Kokin Nakajin ◽  
Takuya Minami ◽  
Masaaki Kawata ◽  
Toshio Fujita ◽  
Katsumi Murofushi ◽  
...  
Keyword(s):  
Machine Learning ◽  
Random Forest ◽  
Physical Properties ◽  
Functional Groups ◽  
Raw Materials ◽  
Functional Materials ◽  
Industrial Applications ◽  
Chemical Information ◽  
Thermosetting Resins ◽  
Mixing Ratios

AbstractThermosetting resins are one of the most widely used functional materials in industrial applications. Although some of the physical properties of thermosetting resins are controlled by changing the functional groups of the raw materials or adjusting their mixing ratios, it was conventionally challenging to construct machine learning (ML) models, which include both mixing ratio and chemical information such as functional groups. To overcome this problem, we propose a machine learning approach based on extended circular fingerprint (ECFP) in this study. First, we predicted the classification of raw materials by the random forest, where ECFP was used as the explanatory variable. Then, we aggregated ECFP for each classification predicted by the random forest. After that, we constructed the prediction model by using the aggregated ECFP, feature quantities of reaction intermediates, and curing conditions of resin as explanatory variables. As a result, the model was able to predict in high accuracy (R^2 = 0.8), for example, the elastic modulus of thermosetting resins. Furthermore, we also show the result of verification of prediction accuracy in first step, such as using the one-hot-encording. Therefore, we confirmed that the properties of thermosetting resins could be predicted using mixed raw materials by the proposed method.

UV Absorption Microspectrophotometry and Histochemistry of Flax and Kenaf

1998 ◽  
Vol 4 (S2) ◽  
pp. 846-847
Author(s):  
D.E. Akin
Keyword(s):  
Microbial Degradation ◽  
Linum Usitatissimum ◽  
Cell Walls ◽  
Industrial Applications ◽  
Hibiscus Cannabinus ◽  
Fiber Cell ◽  
The Other ◽  
Uv Absorption ◽  
Bast Fibers ◽  
Histochemical Tests

Flax (Linum usitatissimum L.) and kenaf (Hibiscus cannabinus L.) are the sources of fibers used for textiles and other industrial applications. Both flax and kenaf produce fibers in the bast region (Fig. 1, 2) which must be separated from other tissues by retting. Although both flax and kenaf are bast fibers, their properties are vastly different. UV absorption microspectrophotometry and histochemistry elucidate their chemistry and structure related to enzymatic retting.Aromatics such as lignins are produced by plants for protection and strength, but their presence inhibits microbial degradation, which is necessary in retting. Histochemical tests indicated variations in the site and type of aromatics within these two plants (1,2). In flax, acid phloroglucinol but not chlorine-sulfite gave positive reactions occasionally in fiber cell walls in the bast. The other cell walls in the bast did not contain aromatics by these tests, although aromatics occurred in the cuticle.

scholarly journals Valorization of Lignin as a Sustainable Component of Structural Materials and Composites: Advances from 2011 to 2019

2020 ◽  
Vol 12 (2) ◽  
pp. 734 ◽  
Author(s):  
Menisha S. Karunarathna ◽  
Rhett C. Smith
Keyword(s):  
Chemical Modification ◽  
Functional Groups ◽  
Carbon Fibers ◽  
Network Structure ◽  
Phenol Formaldehyde ◽  
Construction Materials ◽  
Structural Elements ◽  
Automotive Components ◽  
Future Developments ◽  
Technical Issues

Lignin is the most abundant aromatic biopolymer and is the sustainable feedstock most likely to supplant petroleum-derived aromatics and downstream products. Rich in functional groups, lignin is largely peerless in its potential for chemical modification towards attaining target properties. Lignin’s crosslinked network structure can be exploited in composites to endow them with remarkable strength, as exemplified in timber and other structural elements of plants. Yet lignin may also be depolymerized, modified, or blended with other polymers. This review focuses on substituting petrochemicals with lignin derivatives, with a particular focus on applications more significant in terms of potential commercialization volume, including polyurethane, phenol-formaldehyde resins, lignin-based carbon fibers, and emergent melt-processable waste-derived materials. This review will illuminate advances from the last eight years in the prospective utilization of such lignin-derived products in a range of application such as adhesives, plastics, automotive components, construction materials, and composites. Particular technical issues associated with lignin processing and emerging alternatives for future developments are discussed.

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