Water states and migration in Xinjiang poplar and Mongolian Scotch pine monitored by TD-NMR during drying

Holzforschung ◽  
2018 ◽  
Vol 72 (2) ◽  
pp. 113-123 ◽  
Author(s):  
Zhe Wang ◽  
Xi-Ming Wang ◽  
Zhang-Jing Chen
Keyword(s):  
Bound Water ◽  
Free Water ◽  
Scotch Pine ◽  
Saturation Point ◽  
Time Component ◽  
Long Time ◽  
And Migration ◽  
The Time Domain ◽  
Short Time ◽  
Bound Water Content

AbstractThe time domain nuclear magnetic resonance (TD-NMR) technique was applied to observe the water states, water migration and theT2cutoffof sapwood (sW) and heartwood (hW) of Xinjiang poplar and Mongolian Scotch pine wood during drying. Three components in theT2spectrum could be observed for poplar and pine at room temperature, and a large, short time component and a small, long time component of free water was visible at the melting point of water. During drying, the long timeT2component diminished rapidly above the fiber saturation point (FSP), and almost disappeared close to or below the FSP. The short time components of theT2distributions slightly enlarged with decreasing moisture content (MC) above the FSP but rapidly diminished and shifted to the left side below the FSP. The bound water content estimated based on theT2cutoffis in agreement with previous findings. Free and bound water have been found to be in two primary states both in poplar and pine. The loss of free water was rapid and profound but the bound water slightly increased with decreasing MC above the FSP, and the free water evaporated completely close to the FSP, where the bound water began to disappear significantly.

Water migration in poplar wood during microwave drying studied by time domain nuclear magnetic resonance (TD-NMR)

Holzforschung ◽  
2017 ◽  
Vol 71 (11) ◽  
pp. 881-887 ◽  
Author(s):  
Xinyu Li ◽  
Yulei Gao ◽  
Minghui Zhang ◽  
Ximing Wang ◽  
Xinyue Wei
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Time Domain ◽  
Bound Water ◽  
Free Water ◽  
Microwave Drying ◽  
Drying Rate ◽  
Drying Time ◽  
The Time Domain ◽  
Nuclear Magnetic

AbstractThe migration of bound water and free water has been investigated during microwave drying of wood by the time domain nuclear magnetic resonance (TD-NMR) technique. Both the heartwood (hW) and sapwood (sW) of Beijing poplar (Populus beijingensisW. Y. Hsu) and Qingpi poplar (Populus platyphyllaT. Y. Sun) were studied. The microwave drying is characterized by a fast drying rate, and there is a linear relation between moisture content (MC) and microwave drying time (t). The drying rate of free water is about 2.7 times more rapid than that of bound water. The spin-spin relaxation time (T2) revealed that most of the water was free water situated in smaller pores. The irregular T2 signal amplitudes of free water in hWs indicated that fractional water in smaller pores was transferred into bigger pores during drying.

Moisture in softwoods: fiber saturation point, hydroxyl site content, and the amount of micropores as determined from NMR relaxation time distributions

Holzforschung ◽  
2013 ◽  
Vol 67 (3) ◽  
pp. 291-300 ◽  
Author(s):  
Ville-Veikko Telkki ◽  
Miikka Yliniemi ◽  
Jukka Jokisaari
Keyword(s):  
Melting Point ◽  
Relaxation Times ◽  
Bound Water ◽  
Nmr Relaxation ◽  
Free Water ◽  
Bulk Water ◽  
Fiber Saturation Point ◽  
Saturation Point ◽  
Fiber Saturation ◽  
Nmr Relaxation Times

Abstract Distributions of nuclear magnetic resonance (NMR) relaxation times provide detailed information about the moisture absorbed in wood. In this work, T2*, T2, and T1 distributions were recorded from fresh sapwood and heartwood samples of pine (Pinus sylvestris) and spruce (Picea abies) at various temperatures. Below the melting point of bulk water, free water is frozen and its signal disappears from the distributions. Then, the low-temperature distributions of the unfrozen bound water contain more information about its components, because the large free water peaks hiding some smaller bound water peaks are absent and the exchange between free and bound water is prevented. Comparison of the total moisture signal integrals above and below the bulk melting point enables the determination of fiber saturation point (FSP), which, in this context, denotes the total water capacity of cell wall. T2*, T2, and T1 distributions offer different kinds of information about moisture components. All the peaks in the distributions were assigned, and it was demonstrated that the accessible hydroxyl site content and the amount of micropores can be estimated based on the peak integrals.

scholarly journals Effects of Radio Frequency Tempering on the Texture of Frozen Tilapia Fillets

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2663
Author(s):  
Jiwei Jiang ◽  
Fen Zhou ◽  
Caining Xian ◽  
Yuyao Shi ◽  
Xichang Wang
Keyword(s):  
Radio Frequency ◽  
Bound Water ◽  
Free Water ◽  
Electrode Gap ◽  
Related Factors ◽  
Volumetric Heating ◽  
Fragmentation Index ◽  
Free Water Content ◽  
Tilapia Fillets ◽  
And Migration

Radio frequency (RF) tempering has been proposed as a new alternative method for tempering frozen products because of its advantages of rapid and volumetric heating. In this study, the texture of RF-tempered frozen tilapia fillets was determined under different RF conditions, the effects of related factors on the texture were analyzed, and the mechanisms by which RF tempering affected the texture of the tempered fillets were evaluated. The results show that the springiness (from 0.84 mm to 0.79 mm), cohesiveness (from 0.64 mm to 0.57 mm), and resilience (from 0.33 mm to 0.25 mm) decreased as the electrode gap was increased and the power remained at 600 W, while the shear force increased as the power was increased for the 12 cm electrode gap (from 15.18 N to 16.98 N), and the myofibril fragmentation index (MFI) values were markedly higher at 600 W than at 300 W or 900 W (p < 0.05). In addition, the tempering uniformity had a positive effect on hardness and chewiness. The statistical analysis showed that the texture after RF tempering under different RF conditions correlated relatively strongly with the free water content, cooking loss, and migration of bound water to immobilized water. The decrease in free water and bound water migration to immobilized water resulted in a significant increase in cohesiveness and resilience.

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.

scholarly journals Drying influence on the development of cracks in Eucalyptus logs

BioResources ◽  
2018 ◽  
Vol 14 (1) ◽  
pp. 220-233
Author(s):  
Thiago Magalhães do Nascimento ◽  
Thiago Campos Monteiro ◽  
Edy Eime Pereira Baraúna ◽  
Jordão Cabral Moulin ◽  
Alcinei Mistico Azevedo
Keyword(s):  
Moisture Content ◽  
Water Loss ◽  
Initial Moisture Content ◽  
Genetic Material ◽  
Bound Water ◽  
Free Water ◽  
Moisture Loss ◽  
Surface Cracks ◽  
Saturation Point ◽  
Selection Of

The aim of this study was to evaluate the effect of the moisture loss, diameter, and wood density on the appearance of surface cracks and end splits in Eucalyptus urophylla logs. The drying and emergence of defects were evaluated in 108 logs with diameters ranging from 60 mm to 150 mm from the initial moisture content to the equilibrium moisture content. The defects were measured during this time. Smaller diameter logs dried faster than larger diameter logs and took less time to reach the fiber saturation point. Surface cracks tended to develop during the loss of bound water. End splits developed during free water loss and continued to appear during bound water loss. Smaller diameters presented higher percentages of surface cracks compared with larger diameters, while larger diameters had a tendency for higher percentages of end splits compared with smaller diameters. The density did not influence the total emergence of end splits, but it did influence the total emergence of surface cracks, indicating a possibility for the selection of genetic material with lower tendency for cracking. Overall, the results reinforce the need to control drying at its beginning in order to decrease the risk of defects.

Minimisation of Water Content in Concrete

2016 ◽  
Vol 691 ◽  
pp. 230-238
Author(s):  
Ivan Juríček ◽  
Ľudovít Fillo
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Atmospheric Pressure ◽  
Bound Water ◽  
Free Water ◽  
Point Of View ◽  
Free Water Content ◽  
Normal Atmospheric Pressure ◽  
Moisture Characteristic ◽  
Short Time

In the production of structures made of concrete it is sometimes required to make a completed structure contain a minimum amount of free water. From the point of view of effectiveness of the production process it is also preferred to dry the concrete in a short time and at a reasonable cost. Required for free water content can be limited by various factors (e.g. construction covered by flooring sensitive to humidity, frost resistance, etc.).The moisture characteristic of concrete is verified in civil engineering provided that the concrete is located in the environment with normal atmospheric pressure. By solving the project “Development of methods for structure of thermal vacuum insulated containers” we have met a requirement to produce concrete with extremely low moisture content. It was found out that information about moisture content of concrete obtained by currently used method was unsatisfactory for concrete in the environment with extremely low atmospheric pressure. The research has indicated that usual methods of concrete drying are not sufficient for concrete subjected to vacuum because they don´t eliminate physically bound water.

Changes in the components and content of biological water in the brain of experimental hydrocephalic rabbits

1990 ◽  
Vol 73 (2) ◽  
pp. 274-278 ◽  
Author(s):  
Norihiko Tamaki ◽  
Haruo Yamashita ◽  
Mitsuru Kimura ◽  
Kazumasa Ehara ◽  
Masahiro Asada ◽  
...  
Keyword(s):  
White Matter ◽  
Water Content ◽  
Bound Water ◽  
Free Water ◽  
Periventricular White Matter ◽  
Total Water ◽  
Biological Water ◽  
Cortical Gray Matter ◽  
The Brain ◽  
Bound Water Content

✓ Changes in biological water components and their respective content in the cortical gray matter and periventricular white matter were studied in rabbits rendered hydrocephalic by intracisternal kaolin injection. There was no change in either total water content or free or bound water content in the cortical gray matter at the various stages of hydrocephalus development. While there was no significant change in total water content in the periventricular white matter at any stage of hydrocephalus, free water content was significantly elevated and bound water content was decreased at the acute and subacute stages, with a return to relatively normal levels at the chronic stage. It is concluded that in the periventricular white matter, free water enters the brain across the ependymal lining during the acute and subacute stages of experimental hydrocephalus with a simultaneous reduction in the bound water and that there is some recovery at the chronic stage. It is suggested that alternative drainage pathways may develop in chronic hydrocephalus allowing drainage of free water in the periventricular white matter, which in turn permits bound water to return to relatively normal levels.

scholarly journals An Approach for Computing the Heat Sources in Logs Subjected to Freezing

2018 ◽  
Vol 14 (1) ◽  
pp. 35-49 ◽  
Author(s):  
Nencho Deliiski ◽  
Natalia Tumbarkova
Keyword(s):  
Initial Temperature ◽  
Basic Density ◽  
Internal Heat ◽  
Bound Water ◽  
Free Water ◽  
Freezing Process ◽  
Heat Sources ◽  
Saturation Point ◽  
Suggested Approach ◽  
Internal Heat Sources

Abstract This study suggests an approach for computing the specific energies of the internal heat sources in logs subjected to freezing. The approach maximally considers the physics of the freezing processes of both the free and the bound water in wood. It reflects the influence on the mentioned energies of the wood density above and below the hygroscopic range. It also considers the icing degrees formed separately by both the free and bound water in the logs, as well as the influence of the fiber saturation point of each wood species on its respective amount of non-frozen water depending on temperatures below 272.15 K. Mathematical descriptions of the specific heat energies Qv-fw and Qv-bw released in logs during free water freezing in the range from 0 °C to −1 °C and of the bound water below –1 °C, respectively, have been executed. These descriptions are introduced in own 2D non-linear mathematical model of the freezing process of logs. For the solution of the model and computation of the energies Qv-fw and Qv-bw, a software program based on the suggested approach and mathematical descriptions was prepared in FORTRAN, which was input into the calculation environment of Visual Fortran. With the aid of the program, computations were completed to determine the energies Qv-fw and Qv-bw and their sum, Qv-total of a beech log subjected to freezing. The beech log had a diameter of 0.24 m, a length of 0.48 m, an initial temperature of 20.5 °C, a basic density of 683 kg·m−3, and a moisture content of 0.48 kg·kg–1 during its 30 hours in a freezer at approximately −30 °C.

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