Transformation of the Near-Infrared Bands of Cellulose Surface Hydroxyls under the Influence of Adsorbed Water Molecules

2000 ◽  
Vol 54 (3) ◽  
pp. 420-425 ◽  
Author(s):  
Vitas Švedas
Keyword(s):  
Near Infrared ◽  
Surface Coverage ◽  
Bound Water ◽  
Free Water ◽  
Adsorbed Water ◽  
Water Molecules ◽  
Surface Hydroxyl ◽  
Surface Hydroxyls ◽  
Cellulose Surface ◽  
Hydrogen Bonded

Near-infrared absorption spectra of sulfite cellulose with a varied adsorbed water content were studied. Analysis of the spectra has been made on the basis of previously published relations and results of the cellulose surface hydroxyls' interaction with absorbed water. Spectra of the OH overtone region of 1.3–1.65 μm were deconvoluted to components of cellulose volume and surface hydroxyls as well as to those of absorbed water. Besides the 1.53–1.55 μm component of “bound” water, the 1.42–1.44 μm component of “free” water starts to grow as the surface coverage exceeds 1.5. Comparison of the peak positions of these water components with those of liquid water suggests that bound water is constituted of hydrogen-bonded molecules. The 1.42–1.44 μm component of free water implies nonhydrogen-bonded and partially hydrogen-bonded molecules. The whole 1.363 μm band and a part of the 1.424 μm band of surface hydroxyls turn into the 1.52–1.53 and 1.57–1.59 μm peaks, respectively, after attachment of H2O molecules. The red shift of the surface bands by approximately 780 cm−1 caused by the adsorbate is consistent with a shift of the fundamental OH band of silica gel. The possible chemical, morphological, and physical causes of the two 1.363 and 1.424 m surface hydroxyl bands are discussed.

scholarly journals Water Structure in Proteins in Solid State Studied by Near Infrared Spectroscopy

2017 ◽  
Vol 735 ◽  
pp. 168-172
Author(s):  
Siraporn Soonthonhut ◽  
Alfred A. Christy
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Water Adsorption ◽  
Near Infrared ◽  
Free Water ◽  
Adsorbed Water ◽  
Water Molecules ◽  
Combination Frequency ◽  
Adsorption Of Water ◽  
Combination Frequencies

Water adsorption in proteins is the crucial process of protein folding and structure stabilizing. Adsorption of water on proteins can be evaluated by near-infrared spectroscopy, a useful technique for observing combination frequency of a water molecule. In this work, albumin, lysozyme, and silk, were used as models for α-helix and β-pleated sheet proteins. Their NIR spectra during water adsorption process were measured by using an NIR spectrometer equipped with a transflectance accessory. Moreover, the quantitative adsorption of water was determined by gravimetric technique. The results indicate that, there are five different NIR absorptions arise from the OH combination frequencies of water adsorbed by albumin in the 5300-5100 cm-1 region. But there are only four absorptions for lysozyme and silk. The OH combination frequencies arising from water molecules in albumin indicate that it acquires free water molecules (5280 cm-1) and adsorbed water molecules through carbonyl-water interactions (5248 and 5160 cm-1) and amino-water interactions (5200 and 5120 cm-1). Interestingly, there is no indication for the presence of free water molecules in lysozyme and silk. Furthermore, the gravimetric results indicate that the rate of water adsorbed follows the order RW.Alb<RW.Lys<RW.Sil and total mass of water adsorbed per gram solid follows the order WAlb<WLys=WSil.

scholarly journals Water Adsorption to Leaves of Tall Cryptomeria japonica Tree Analyzed by Infrared Spectroscopy under Relative Humidity Control

Plants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1107
Author(s):  
Wakana A. Azuma ◽  
Satoru Nakashima ◽  
Eri Yamakita ◽  
Tamihisa Ohta
Keyword(s):  
Hydrogen Bonding ◽  
Relative Humidity ◽  
Cryptomeria Japonica ◽  
Water Adsorption ◽  
Bound Water ◽  
Free Water ◽  
High Water ◽  
Water Molecules ◽  
Cross Sectional ◽  
Tissue Properties

Leaf water storage is a complex interaction between live tissue properties (anatomy and physiology) and physicochemical properties of biomolecules and water. How leaves adsorb water molecules based on interactions between biomolecules and water, including hydrogen bonding, challenges our understanding of hydraulic acclimation in tall trees where leaves are exposed to more water stress. Here, we used infrared (IR) microspectroscopy with changing relative humidity (RH) on leaves of tall Cryptomeria japonica trees. OH band areas correlating with water content were larger for treetop (52 m) than for lower-crown (19 m) leaves, regardless of relative humidity (RH). This high water adsorption in treetop leaves was not explained by polysaccharides such as Ca-bridged pectin, but could be attributed to the greater cross-sectional area of the transfusion tissue. In both treetop and lower-crown leaves, the band areas of long (free water: around 3550 cm−1) and short (bound water: around 3200 cm−1) hydrogen bonding OH components showed similar increases with increasing RH, while the band area of free water was larger at the treetop leaves regardless of RH. Free water molecules with longer H bonds were considered to be adsorbed loosely to hydrophobic CH surfaces of polysaccharides in the leaf-cross sections.

Low-temperature FTIR spectroscopy provides evidence for protein-bound water molecules in eubacterial light-driven ion pumps

2018 ◽  
Vol 20 (5) ◽  
pp. 3165-3171 ◽  
Author(s):  
Yurika Nomura ◽  
Shota Ito ◽  
Miwako Teranishi ◽  
Hikaru Ono ◽  
Keiichi Inoue ◽  
...  
Keyword(s):  
Low Temperature ◽  
Water Molecule ◽  
Ftir Spectroscopy ◽  
Proton Pump ◽  
Bound Water ◽  
Water Molecules ◽  
Ion Pumps ◽  
Functional Determinant ◽  
Ftir Study ◽  
Hydrogen Bonded

The present FTIR study showed that eubacterial light-driven H+, Na+ and Cl− pump rhodopsins contain strongly hydrogen-bonded water molecule, the functional determinant of light-driven proton pump. This explains well the asymmetric functional conversions of light-driven ion pumps.

scholarly journals Dielectrometry of hydration of fl avin mononucleotide and DNA

2021 ◽  
Vol 26 (3) ◽  
pp. 46-53
Author(s):  
V. Kashpur ◽  
◽  
O. Khorunzhaya ◽  
D. Pesina ◽  
◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Bound Water ◽  
Free Water ◽  
Dna Interaction ◽  
Flavin Mononucleotide ◽  
Water Molecules ◽  
Extremely High Frequency ◽  
Aqueous Solvent ◽  
The Difference ◽  
Solvent Molecules

Subject and Purpose. The elucidation of the molecular mechanisms of action of biomolecules is necessary for the development of state-of-the-art means of diagnosing and treatment. Dielectric studies in the millimeter wave range are effective for puzzling out the nature of the interaction of biomolecules with a surrounding aqueous solvent. Flavin mononucleotide (FMN), which can kill microorganisms and destroy cancer cells, is of particular interest. The aim of the work is to recognize hydration effects (changes in the state of water molecules) in FMN solutions. Methods and Methodology. The complex dielectric permittivity (CDP) is measured in the EHF range. Knowing the difference between the CDP of FMN solution and the CDP of water we find the difference, D es , between the effective dielectric permittivities in terms of the Debye theory of polar liquids. Since the relaxation time of dipoles of bound water is one or two orders of magnitude longer than that of free water, the amount of the difference D es characterizes the hydration of biomolecules. At low concentrations, this difference is proportional to the number of bound water molecules. Results. It has been shown that approximately18 water molecules are bound to the FMN molecule. Groups of atoms as the most probable hydration centers (primarily due to the hydrogen bonds) have been indicated. As the pH decreases, the number of water molecules bound to the Flavin mononucleotide increases to 21. The study of the FMN–DNA solution has shown that one nucleotide accounts for 25–26 bound water molecules in total. However, composing hydration numbers assumes a quantity of components less than 20. An assumption is made that the additional components are due to the cooperative nature of the hydration, leading to the fact that even if some solvent molecules do not come into a direct contact with hydration centers, they are under the influence of biomolecules all the same. Conclusion. Extremely-high-frequency dielectrometry is an effective method of research into the interaction of biomolecules with a water-ionic solvent. A FMN hydration model has been proposed, which indicates probable hydration centers and tells a measure of their effect on the solvent. It has been found that the FMN with DNA interaction increases the number of bound water molecules per one nucleotide of the DNA. The obtained results have been compared to the existing models of the DNA with FMN interaction.

scholarly journals Analysis of water state adsorbed by cellulose fibers

2019 ◽  
Vol 58 (5) ◽  
pp. 24-31
Author(s):  
Daria S. Masas ◽  
◽  
Maria S. Ivanova ◽  
Gocha Sh. Gogelashvili ◽  
Alexander S. Maslennikov ◽  
...  
Keyword(s):  
Adsorbed Water ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Active Centers ◽  
Surface Hydroxyl ◽  
Spin Lattice ◽  
Donor Acceptor ◽  
Elementary Fibrils

Modernized model of microfibril cellulose layered structure is proposed. This model considers presence of slit-shaped micropores in space between elementary fibrils and cellulose microfibrils. It’s discussed the nature of donor-acceptor hydrogen bonds formation: intra-, intermolecular, and interlayer bonds inherent in each glucopyranous cellulose link. It’s described the mechanism of water molecules specific adsorption interactions in a monolayer with active centers located on the hydrophilic surfaces of elementary fibrils. Dipole-dipole energy transition into energy of hydrogen bond is discussed during adsorption process between active centers of cellulose and water adsorptive molecules. Analysis of water molecules dipole-dipole interactions with surface hydroxyl groups of cellulose showed that at distance of 2.5-3 Å energy of this interaction transforms into energy of hydrogen bond. It is discussed the formation mechanism of water molecules donor-acceptor bonds with cellulose surface hydroxyl groups. Thermodynamic parameters characterizing adsorbate state the in these layers are determined by proton magnetic relaxation and sorption measurements. It’s established the possibility of determining adsorption net heat in bilayer considering Arrhenius nature of adsorbate thermal molecular motions correlation times. Increase in entropy of adsorbed water during adsorption process is revealed basis on Vant Hoff equation and certain adsorption equilibrium constant. The calculation established that distance between nearest active centers of cellulose is 6.5 Å. This leads to disunity of adsorbed water molecules and allows application of Langmuir and BET adsorption theory. Analysis of spin-lattice relaxation times dependence on cellulose moisture content made it possible to establish the cause of its crystallite wedging from adsorbed water molecules at adsorption initial stages. Decline of the spin-lattice relaxation unambiguously indicates the process of cellulose dispersion into its structural elements. It was established that during adsorption a part of the internal regions of crystallites passes to their surface with participation of cellulose hydroxyl groups. During desorption reverse process is observed.

Recent advancements in plant aquaphotomics – Towards understanding of “drying without dying” phenomenon and its implications

NIR news ◽  
2019 ◽  
Vol 30 (5-6) ◽  
pp. 22-25 ◽  
Author(s):  
Jelena Muncan ◽  
Shinichiro Kuroki ◽  
Daniela Moyankova ◽  
Hiroyuki Morita ◽  
Stefka Atanassova ◽  
...  
Keyword(s):  
Graduate School ◽  
Biomedical Applications ◽  
Climate Changes ◽  
Near Infrared ◽  
Water Structure ◽  
Free Water ◽  
Food Preservation ◽  
Protective Mechanism ◽  
Water Molecules ◽  
Significant Step

The research team of Kobe University’s Graduate School of Agriculture Science, led by Professor Dr Roumiana Tsenkova and a research group from Agrobioinstitute in Sofia, Bulgaria led by Professor Dr Dimitar Djilianov, recently made a significant step forward in understanding the “drying without dying” phenomenon in resurrection plants – a small group of plant species which are able to survive long periods without water. Using aquaphotomics and near infrared spectroscopy, the entire process of desiccation and subsequent rehydration in one such plant – Haberlea rhodopensis was monitored non-destructively and compared with botanically similar, non-resurrection species Deinostigma eberhardtii. The research found that during drying, resurrection plant performs controlled, organized restructuring of water molecular network in its leaves as a preparation for full desiccation which is characterized by accumulation of water molecular dimers and water molecules with four hydrogen bonds, while free water molecules are drastically diminished. This regulation of water structure in the leaves appears to be the protective mechanism against dehydration-induced damages of the tissues which ensures survival in the absence of water. The discovery that water molecular structure is important for preservation of plant tissues not only opens up new possibilities for bioengineering of crops better adapted to combat climate changes but may also have important implications for food preservation industry, preservation of tissues in medicine and in biomedical applications.

Bound Water in Cement Pastes and its Significance for Pore Solution Compositions

1986 ◽  
Vol 85 ◽  
Author(s):  
H. F. W. Taylor
Keyword(s):  
Fly Ash ◽  
Pore Solution ◽  
Bound Water ◽  
Free Water ◽  
Adsorbed Water ◽  
Interlayer Water ◽  
Structural Water ◽  
Cement Pastes ◽  
Evaporable Water ◽  
Definition Of

ABSTRACTThe problem of defining bound water in a cement paste is discussed; a reasonable definition is one that includes interlayer water in C-S-H and AFm phases, structural water in ettringite, and adsorbed water, but not water in micropores or in larger pores. On this basis, structural considerations indicate a value of around 32% on the ignited weight for a fully hydrated paste. ‘Non-evaporable’ water, typically around 22% on the ignited weight at full hydration, cannot be identified with bound water, because dehydration to the state in which only non-evaporable water remains causes major loss of interlayer water and destruction of ettringite. In the interpretation of pore solution data, the definition of bound water, and the value assumed for this quantity, are important, because the ionic concentrations in the pore solution are greatly affected by the volume of free water available to dissolve them. If cement is partially replaced by low calcium fly ash, the quantity of bound water at any given age is substantially reduced. This effect contributes to the relatively low concentrations of alkali metal and hydroxyl ions that are observed in the pore solutions of many portland-fly ash cement pastes.

scholarly journals Interactions of Linearly Polarized and Unpolarized Light on Kiwifruit Using Aquaphotomics

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 494
Author(s):  
Damenraj Rajkumar ◽  
Rainer Künnemeyer ◽  
Harpreet Kaur ◽  
Jevon Longdell ◽  
Andrew McGlone
Keyword(s):  
Near Infrared ◽  
Polarized Light ◽  
Bound Water ◽  
Free Water ◽  
Nir Spectroscopy ◽  
Soluble Solids ◽  
Unpolarized Light ◽  
Standard Normal Variate ◽  
Linearly Polarized ◽  
Solids Content

Near infrared (NIR) spectroscopy is an important tool for predicting the internal qualities of fruits. Using aquaphotomics, spectral changes between linearly polarized and unpolarized light were assessed on 200 commercially grown yellow-fleshed kiwifruit (Actinidia chinensis var. chinensis ‘Zesy002’). Measurements were performed on different configurations of unpeeled (intact) and peeled (cut) kiwifruit using a commercial handheld NIR instrument. Absorbance after applying standard normal variate (SNV) and second derivative Savitzky–Golay filters produced different spectral features for all configurations. An aquagram depicting all configurations suggests that linearly polarized light activated more free water states and unpolarized light activated more bound water states. At depth (≥1 mm), after several scattering events, all radiation is expected to be fully depolarized and interactions for incident polarized or unpolarized light will be similar, so any observed differences are attributable to the surface layers of the fruit. Aquagrams generated in terms of the fruit soluble solids content (SSC) were similar for all configurations, suggesting the SSC in fruit is not a contributing factor here.

Study on the Moisture Distribution within the Wood Treated with Microwave

2011 ◽  
Vol 327 ◽  
pp. 105-108 ◽  
Author(s):  
Jian Fang Yu ◽  
Ji Long Guo ◽  
Jing Ya Nan ◽  
Bing Hu Sun
Keyword(s):  
Relaxation Time ◽  
Bound Water ◽  
Free Water ◽  
Microwave Treatment ◽  
Moisture Distribution ◽  
Microwave Drying ◽  
Water Molecules ◽  
Saturation Point ◽  
Initial Stage ◽  
Before And After

In this paper, Siberian elm (Ulmus pumila L) which was regarded as our research object was measured with the technology of Nuclear Magnetic Resonance (NMR) before and after being treated with microwave at different periods of time. By comparing the spin - spin relaxation time of hydrogen nuclear (T2) which can reflect the mobility of water molecules, the states and changes of the moisture distribution within the wood in the process of microwave treatment have been analyzed. The results indicate that in the initial stage of drying, the degree of the decline in bound water is greater than that in free water, for there may be a process of the transformation from bound water to free water; With the drying going on, the movement and expulsion mainly happen to free water above the fiber saturation point (FSP); In the later stage of drying, when the moisture content decreases near the FSP, bound water has also begun moving significantly on the expulsion of plenty of free water. In the final stage of drying, the decrease of hydrogen bonds in water molecules resulting from a plentiful reduction in free water, as well as the increased permeability within the wood caused by the microwave drying makes the relaxation time of free water to rise up.

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