Water sorption in wood and modified wood at high values of relative humidity. Part 2: Appendix. Theoretical assessment of the amount of capillary water in wood microvoids

Holzforschung ◽  
2010 ◽  
Vol 64 (3) ◽  
Author(s):  
Emil Tang Engelund ◽  
Lisbeth G. Thygesen ◽  
Preben Hoffmeyer
Keyword(s):  
Relative Humidity ◽  
Theoretical Study ◽  
Capillary Condensation ◽  
Small Contribution ◽  
Structural Elements ◽  
Capillary Water ◽  
Bordered Pits ◽  
Condensed Water ◽  
Theoretical Assessment ◽  
Theoretical Amount

Abstract A theoretical study of the amount of moisture held in wood as capillary condensed water in the relative humidity (RH) range of 90–99.9% is carried out. The study is based on idealized geometries of the softwood structure related to micrographs. It is confined to structural elements such as bordered pits and the pointed ends of tracheids. The theoretical amount of water in these elements is found by employing the Kelvin equation. An equal amount of earlywood and latewood cells with different geometries and with different amounts of pits is assumed. The effect of pit aspiration is considered, and different degrees of pit aspiration are assigned to earlywood and latewood. We suggest based on the results that capillary condensation makes only a very small contribution to the equilibrium moisture content. At 99.9% RH the contribution amounts to less than 0.0035 kg water per kg dry wood. This is in line with the experimental results presented in Part 1 of this study.

Water sorption in wood and modified wood at high values of relative humidity. Part I: Results for untreated, acetylated, and furfurylated Norway spruce

Holzforschung ◽  
2010 ◽  
Vol 64 (3) ◽  
Author(s):  
Lisbeth G. Thygesen ◽  
Emil Tang Engelund ◽  
Preben Hoffmeyer
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Norway Spruce ◽  
Water Sorption ◽  
Capillary Condensation ◽  
Theoretical Contribution ◽  
Low Field ◽  
Condensed Water ◽  
Relaxation Curves ◽  
Curve Form

Abstract Desorption isotherms at 20°C for untreated, acetylated, and furfurylated Norway spruce [Picea abies (L.) Karst.] sapwood were established in the 91.9–99.9% relative humidity (RH) range. Three methods were employed to secure various constant RH levels: saturated salt solutions, climate chambers, and the pressure plate technique. The curve form for the untreated samples did not show an upward bend, except perhaps above 99.5% RH, indicating that – contrary to what has hitherto been assumed – capillary condensation does not play a significant role for water sorption in wood below fiber saturation. Three additional results corroborate this conclusion: (1) calculation of the theoretical contribution of capillary condensation to the moisture content (MC) in wood based on idealized microstructural geometries by means of the Kelvin and Laplace equations resulted in very small contributions to the equilibrium moisture content (EMC), i.e., below 0.35% moisture at 99.9% RH. (2) The ratio between the EMC of acetylated and untreated samples did not show an increasing trend for increasing RH, as would have been the case if capillary condensation had taken place in both untreated and acetylated wood. (3) Low field time domain nuclear magnetic resonance results showed that only the relaxation curves from the furfurylated samples were affected systematically by freezing, indicating that neither untreated nor acetylated wood contained significant amounts of capillary condensed water.

scholarly journals Value Orientations in Education System: Approach, Interpretation, and Formation

2022 ◽  
Author(s):  
Diana Antoci ◽  
Keyword(s):  
Young People ◽  
Theoretical Study ◽  
Value Orientation ◽  
Value Orientations ◽  
Emotional States ◽  
Structural Elements ◽  
Structural Components ◽  
Pedagogical Model ◽  
Constitutive Components ◽  
Development And Validation

The implemented theoretical study has revealed various scientific positions aimed at: interpreting the concepts of value and value orientation; finding controversial positions and affinities in the use of “value” and “value orientation” concepts; identifyingambiguous positions on structural elements of value orientation and value formation mechanism. The purpose of undertakenresearch was theoretical, experimental and methodological in nature, outlining formation of value orientations in adolescence and youth ages.The developed definitions and determined structural components of value orientations allowed initiation of an experimental investigation of value orientations in adolescents and young people through which interrelation between the constitutive components of value orientation was confirmed, the specifics of values in adolescents and young people was emphasized. Outlining the specifics of value orientation structure led to identification of criteria, indicators and descriptors and to development and validation of a Questionnaire for Value Orientation Assessment. The results of experimental study laid the basis for development and recognition of a Pedagogical Model for formation of value orientations in adolescents and young people. The previously identified mechanism for formation of values and functioning of value orientations was transposed into the nucleus of the Pedagogical Model, which included the following components: behaviour, emotional states, attitudes, convictions, and values. In order to identify the methodology for forming value orientations in the formal, informal and non-formal educational environment, the principles of humanistic, constructivist and cognitivist education, strategies, conditions were highlighted, which ensure a dynamic progress in general development of the personality, implicitly of value orientations, and which is taken into account in framework ofa formative experiment.The data obtained from the validation of the developed Pedagogical Model confirmed its effectiveness and proved that it was a multidimensional one, which could be of great benefit to specialists in the field of Education Sciences and teachers from schools and higher educationalinstitutions.

Experimental–theoretical study of high-cycle failure of structural elements of VZh-159 alloy

2016 ◽  
Vol 45 (1) ◽  
pp. 25-31 ◽  
Author(s):  
A. A. Antipov ◽  
A. N. Gorokhov ◽  
V. A. Gorokhov ◽  
D. A. Kazakov ◽  
S. A. Kapustin
Keyword(s):  
Theoretical Study ◽  
Structural Elements

scholarly journals Optimization of bioinspired triangular patterns for water condensation and transport

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190127 ◽  
Author(s):  
Dong Song ◽  
Bharat Bhushan
Keyword(s):  
Relative Humidity ◽  
Pressure Gradient ◽  
Surface Temperature ◽  
Dew Point ◽  
Laplace Pressure ◽  
Theme Issue ◽  
Water Condensation ◽  
Water Collection ◽  
Condensed Water ◽  
Droplet Condensation

Water condenses on a surface in ambient environment if the surface temperature is below the dew point. For water collection, droplets should be transported to storage before the condensed water evaporates. In this study, Laplace pressure gradient inspired by conical spines of cactus plants is used to facilitate the transport of water condensed in a triangular pattern to the storage. Droplet condensation, transportation and water collection rate within the bioinspired hydrophilic triangular patterns with various lengths and included angles, surrounded by superhydrophobic regions, were explored. The effect of relative humidity was also explored. This bioinspired technique can be used to develop efficient water collection systems. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

scholarly journals Scalable Fabrication of Highly Flexible Porous Polymer-Based Capacitive Humidity Sensor Using Convergence Fiber Drawing

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1985 ◽  
Author(s):  
Maryam Mesgarpour Tousi ◽  
Yujing Zhang ◽  
Shaowei Wan ◽  
Li Yu ◽  
Chong Hou ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Humidity Sensor ◽  
Capillary Condensation ◽  
Porous Polymer ◽  
Good Sensitivity ◽  
Fiber Drawing ◽  
Small Temperature ◽  
Flexible Fiber ◽  
Capacitive Humidity Sensor

In this study, we fabricated a highly flexible fiber-based capacitive humidity sensor using a scalable convergence fiber drawing approach. The sensor’s sensing layer is made of porous polyetherimide (PEI) with its porosity produced in situ during fiber drawing, whereas its electrodes are made of copper wires. The porosity induces capillary condensation starting at a low relative humidity (RH) level (here, 70%), resulting in a significant increase in the response of the sensor at RH levels ranging from 70% to 80%. The proposed humidity sensor shows a good sensitivity of 0.39 pF/% RH in the range of 70%–80% RH, a maximum hysteresis of 9.08% RH at 70% RH, a small temperature dependence, and a good stability over a 48 h period. This work demonstrates the first fiber-based humidity sensor fabricated using convergence fiber drawing.

Humidity Effects and Aging Behavior in Granular Media

1998 ◽  
Vol 543 ◽  
Author(s):  
F. Restagno ◽  
H. Gayvallet ◽  
L. Bocquet ◽  
E. Charlaix
Keyword(s):  
Relative Humidity ◽  
Granular Medium ◽  
Granular Media ◽  
Capillary Condensation ◽  
Glass Beads ◽  
Aging Behavior ◽  
Humidity Effects ◽  
Small Glass ◽  
Aging Properties ◽  
Maximum Stability

AbstractWe present a study of humidity effects on the maximum stability angle in granular media. We show that a granular medium of small glass beads exhibits aging properties: the first avalanche angle increases logarithmically with the resting time of the pile. This aging behavior is found to depend on the relative humidity of the surrounding atmosphere. A short interpretation of this effect, based on a model of activated capillary condensation, is proposed.

scholarly journals Nanoscale Wetting of Single Viruses

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5184
Author(s):  
Annalisa Calò ◽  
Aitziber Eleta-Lopez ◽  
Thierry Ondarçuhu ◽  
Albert Verdaguer ◽  
Alexander M. Bittner
Keyword(s):  
Relative Humidity ◽  
Viral Infections ◽  
High Sensitivity ◽  
Water Layer ◽  
Dynamic Force ◽  
Force Microscopy ◽  
Virus Particles ◽  
Ambient Relative Humidity ◽  
Atomic Force ◽  
Condensed Water

The epidemic spread of many viral infections is mediated by the environmental conditions and influenced by the ambient humidity. Single virus particles have been mainly visualized by atomic force microscopy (AFM) in liquid conditions, where the effect of the relative humidity on virus topography and surface cannot be systematically assessed. In this work, we employed multi-frequency AFM, simultaneously with standard topography imaging, to study the nanoscale wetting of individual Tobacco Mosaic virions (TMV) from ambient relative humidity to water condensation (RH > 100%). We recorded amplitude and phase vs. distance curves (APD curves) on top of single virions at various RH and converted them into force vs. distance curves. The high sensitivity of multifrequency AFM to visualize condensed water and sub-micrometer droplets, filling gaps between individual TMV particles at RH > 100%, is demonstrated. Dynamic force spectroscopy allows detecting a thin water layer of thickness ⁓1 nm, adsorbed on the outer surface of single TMV particles at RH < 60%.

A theoretical study of inlet relative humidity control in PEM fuel cell

2011 ◽  
Vol 36 (18) ◽  
pp. 11871-11885 ◽  
Author(s):  
K.H. Wong ◽  
K.H. Loo ◽  
Y.M. Lai ◽  
Siew-Chong Tan ◽  
Chi K. Tse
Keyword(s):  
Fuel Cell ◽  
Relative Humidity ◽  
Theoretical Study ◽  
Pem Fuel Cell ◽  
Humidity Control

Analysis of Capillary Condensation of Vapor in Multi-Wall Carbon Nanotubes

2011 ◽  
Vol 483 ◽  
pp. 694-698
Author(s):  
Wei Wang ◽  
Xin Wang ◽  
Tuo Li ◽  
Wei Ping Chen
Keyword(s):  
Carbon Nanotubes ◽  
Relative Humidity ◽  
Humidity Sensor ◽  
Quartz Crystal ◽  
Capillary Condensation ◽  
Equivalent Model ◽  
Sensing Element ◽  
Multi Wall Carbon Nanotubes ◽  
As Adsorption ◽  
Humidity Environment

Multi-wall Carbon Nanotubes (MWNTs) is the new hotspot material as the active sensing element, but there is no certain theory on the phenomenon of the vapor's capillary condensation in MWNTs for the present. This paper presents a new theory that the capillary condensation of vapor in MWNTs mostly occur in the internal hollow tube, according to the calculation of equivalent model of MWNTs. A kind of carbon nanotubes (CNTs) humidity sensor based on quartz crystal microbalance was fabricated, CNTs employed as adsorption materials. The sensor was put in 11% and 97% relative humidity environment in experimental, and the value of MH2O/MCNT was calculated. The theory in this paper is proved by the comparison between the experimental and the analysis results.

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