Raman spectra were acquired in situ during tensile straining of mechanically isolated fibers of spruce latewood. Stress-strain curves were evaluated along with band positions and intensities to monitor molecular changes due to deformation. Strong correlations (r = 0.99) were found between the shift of the band at 1097 cm(-1) corresponding to the stretching of the cellulose ring structure and the applied stress and strain. High overall shifts (-6.5 cm(-1)) and shift rates (-6.1 cm(-1)/GPa) were observed. After the fiber failed, the band was found on its original position again, proving the elastic nature of the deformation. Additionally, a decrease in the band height ratio of the 1127 and 1097 cm(-1) bands was observed to go hand in hand with the straining of the fiber. This is assumed to reflect a widening of the torsion angle of the glycosidic C-O-C bonding. Thus, the 1097 cm(-1) band shift and the band height ratio enable one to follow the stretching of the cellulose at a molecular level, while the lignin bands are shown to be unaffected. Observed changes in the OH region are shown and interpreted as a weakening of the hydrogen-bonding network during straining. Future experiments on different native wood fibers with variable chemical composition and cellulose orientation and on chemically and enzymatically modified fibers will help to deepen the micromechanical understanding of plant cell walls and the associated macromolecules.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/bm060236g | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Molecular investigation of bamboo during stress relaxation using custom-built mechanical loading platform coupled with Raman spectroscopy.
Int J Biol Macromol
November 2024
Department of Biomaterials, International Center for Bamboo and Rattan, No. 8 Futong Eastern Street, Chaoyang District, Beijing 100102, China; SFA and Beijing Co-Built Key Laboratory of Bamboo and Rattan Science & Technology, State Forestry Administration, Beijing 100102, China. Electronic address:
Bamboo holds significant potential as a substitute for plastics. Stress relaxation is a critical property during the fixation stage of plastic formation for bamboo products intended to replace plastic. However, research on this topic has been limited.
View Article and Find Full Text PDFApplication of ATR-FTIR for Green Arabica Bean Shelf-Life Determination in Accelerated Storage.
Foods
July 2024
School of Agro-Industry, Mae Fah Luang University, Chiang Rai 57100, Thailand.
Coffee bean oxidation is associated with enzymatic and non-enzymatic browning, the degradation of desirable aromatic compounds, the development of undesirable flavors, increased susceptibility to microbial spoilage, and volatile compound losses. This study investigated natural dry process (DP) and honey process (HP) green coffee beans stored in GrainPro bags for 0, 5, 10, and 20 days under accelerated storage conditions at 30 °C, 40 °C, and 50 °C with relative humidity of 50%. A kinetic model was used to estimate the shelf life of the green coffee beans.
View Article and Find Full Text PDFGreen alternatives to petroleum-based plastics: production of bioplastic from Pseudomonas neustonica strain NGB15 using waste carbon source.
Environ Sci Pollut Res Int
May 2024
Department of Molecular Biology and Genetics, Faculty of Science, Erzurum Technical University, Erzurum, Turkey.
Article Synopsis
- Polyhydroxyalkanoates (PHAs) are being explored as eco-friendly alternatives to traditional plastics due to their biodegradability and biocompatibility, but cost-effective production remains a challenge.
- The study optimized production conditions using waste substrates, identifying Pseudomonas neustonica NGB15 as the most efficient bacteria under specific conditions (30 g/L banana peel powder, 25°C, pH 8, 4-day incubation).
- Results showed successful production of poly-β-hydroxybutyrate (3.34 g/L) highlighted by significant FTIR peaks, indicating the positive potential for low-cost fermentation in PHA bioproduction.
Kinetic study of thermal degradation of flaxseed oil and moringa oil blends with physico-chemical, oxidative stability index (OSI) and shelf-life prediction.
J Food Sci Technol
April 2024
Defence Food Research Laboratory, Siddhartha Nagar, Mysore, India.
The thermal degradation kinetics of flaxseed oil (FSO) and moringa oil (MO) blends with soyabean oil (SOY; 80%), rice bran oil (RBO; 80%), cotton seed oil (CSO; 80%) and sunflower oil (SFO; 80%) with Rancimat equipment. There was no significant ( ≤ 0.05) difference observed in the specific gravity (SG), density (D), and refractive index (RI) values of the MO and FSO blends, while the rancidity parameters showed the opposite variations.
View Article and Find Full Text PDFAccurate Potential Energy Surfaces Using Atom-Centered Potentials and Minimal High-Level Data.
J Phys Chem A
September 2023
Department of Chemistry, University of British Columbia, 3247 University Way, Kelowna, British Columbia V1V 1V7, Canada.
We demonstrate that a Δ-density functional theory (Δ-DFT) approach based on atom-centered potentials (ACPs) represents a computationally inexpensive and accurate method for representing potential energy surfaces (PESs) for the HONO and HFCO molecules and vibrational frequencies derived therefrom. Using as few as 100 CCSD(T)-F12a reference energies, ACPs developed for use with B3LYP/def2-TZVPP are shown to produce PESs for HONO and HFCO with mean absolute errors of 27.7 and 5.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!