scholarly journals Modeling of the Energy for Bound Water Freezing in Logs Subjected to Refrigeration

2020 ◽  
Author(s):  
Nencho Deliiski ◽  
Natalia Tumbarkova
Keyword(s):  
Bound Water

Mathematical Models of Papermaking

2001 ◽  
Vol 6 (1) ◽  
pp. 9-19 ◽  
Author(s):  
A. Buikis ◽  
J. Cepitis ◽  
H. Kalis ◽  
A. Reinfelds ◽  
A. Ancitis ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Initial Value Problems ◽  
Moisture Transfer ◽  
Bound Water ◽  
Drying Process ◽  
Initial Value ◽  
First Order ◽  
Heat And Moisture ◽  
The Mathematical Model ◽  
The Web

The mathematical model of wood drying based on detailed transport phenomena considering both heat and moisture transfer have been offered in article. The adjustment of this model to the drying process of papermaking is carried out for the range of moisture content corresponding to the period of drying in which vapour movement and bound water diffusion in the web are possible. By averaging as the desired models are obtained sequence of the initial value problems for systems of two nonlinear first order ordinary differential equations. 

scholarly journals Elucidating the Molecular Mechanisms for the Interaction of Water with Polyethylene Glycol-Based Hydrogels: Influence of Ionic Strength and Gel Network Structure

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 845
Author(s):  
Xin Yang ◽  
Bronwin Dargaville ◽  
Dietmar Hutmacher
Keyword(s):  
Polyethylene Glycol ◽  
Ionic Strength ◽  
Molecular Mechanisms ◽  
Repeat Unit ◽  
Bound Water ◽  
Weight Fraction ◽  
Swelling Ratio ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Hydrogel System

The interaction of water within synthetic and natural hydrogel systems is of fundamental importance in biomaterial science. A systematic study is presented on the swelling behavior and states of water for a polyethylene glycol-diacrylate (PEGDA)-based model neutral hydrogel system that goes beyond previous studies reported in the literature. Hydrogels with different network structures are crosslinked and swollen in different combinations of water and phosphate-buffered saline (PBS). Network variables, polyethylene glycol (PEG) molecular weight (MW), and weight fraction are positively correlated with swelling ratio, while “non-freezable bound water” content decreases with PEG MW. The presence of ions has the greatest influence on equilibrium water and “freezable” and “non-freezable” water, with all hydrogel formulations showing a decreased swelling ratio and increased bound water as ionic strength increases. Similarly, the number of “non-freezable bound water” molecules, calculated from DSC data, is greatest—up to six molecules per PEG repeat unit—for gels swollen in PBS. Fundamentally, the balance of osmotic pressure and non-covalent bonding is a major factor within the molecular structure of the hydrogel system. The proposed model explains the dynamic interaction of water within hydrogels in an osmotic environment. This study will point toward a better understanding of the molecular nature of the water interface in hydrogels.

scholarly journals Description of the concrete carbonation process with adjusted depth-resolved thermogravimetric analysis

2021 ◽  
Author(s):  
Nico Vogler ◽  
Philipp Drabetzki ◽  
Mathias Lindemann ◽  
Hans-Carsten Kühne
Keyword(s):  
Calcium Hydroxide ◽  
Bound Water ◽  
Reference Method ◽  
Microscopic Analysis ◽  
Limestone Powder ◽  
Gravimetric Analysis ◽  
Sample Material ◽  
Accelerated Carbonation ◽  
Temperature Range ◽  
Carbonation Process

AbstractThe thermal gravimetric analysis (TG) is a common method for the examination of the carbonation progress of cement-based materials. Unfortunately, the thermal properties of some components complicate the evaluation of TG results. Various hydrate phases, such as ettringite (AFt), C–S–H and AFm, decompose almost simultaneously in the temperature range up to 200 °C. Additionally, physically bound water is released in the same temperature range. In the temperature range between 450 °C and 600 °C, the decomposition of calcium hydroxide and amorphous or weakly bound carbonates takes place simultaneously. Carbonates, like calcite, from limestone powder or other additives may be already contained in the noncarbonated sample material. For this research, an attempt was made to minimise the influence of these effects. Therefore, differential curves from DTG results of noncarbonated areas and areas with various states of carbonation of the same sample material were calculated and evaluated. Concretes based on three different types of cement were produced and stored under accelerated carbonation conditions (1% CO2 in air). The required sample material was obtained by cutting slices from various depths of previously CO2-treated specimen and subsequent grinding. During the sample preparation, a special attention was paid that no additional carbonation processes took place. As reference method for the determination of the carbonation depth, the sprayed application of phenolphthalein solution was carried out. Microscopic analysis was examined to confirm the assumptions made previously. Furthermore, the observed effect of encapsulation of calcium hydroxide by carbonates caused by the accelerated carbonation conditions was examined more closely.

scholarly journals Synchrotron radiation macromolecular crystallography: our science and spin offs

2014 ◽  
Vol 70 (a1) ◽  
pp. C10-C10
Author(s):  
John Helliwell
Keyword(s):  
Synchrotron Radiation ◽  
Protein Complexes ◽  
Bound Water ◽  
Water Structure ◽  
Public Understanding ◽  
Anomalous Scattering ◽  
Structural Studies ◽  
Macromolecular Crystallography ◽  
Time Resolved ◽  
Chemical Crystallography

I will give an overview of synchrotron radiation (SR) in macromolecular crystallography (MX) instrumentation, methods and applications from the early days to the present, including the evolution of SR sources and on to the `ultimate storage ring'. The build of dedicated beamlines for resonant anomalous scattering, large unit cells, ever smaller crystals and studies up to ultra-high resolution are core benefits. Results include a high output of PDB depositions, the successful use of microcrystals, pushing the frontiers of using high and low photon energies and time-resolved structural studies at even sub-nanosecond resolutions. These intensively physics based developments will be complemented by biological and chemical crystallography research results, encompassing catalysis and marine coloration, as well as the public understanding of our science and its impacts. Spin off benefits include services to the pharmaceutical industry and helping develop chemical crystallography uses of SR. The development of the Laue method with SR has led to pioneering spin off developments in neutron MX, including transfer of the well validated Daresbury Laue software to various neutron facilities worldwide. Neutron MX is gathering pace as new instrumentation and dedicated sample preparation facilities are in place at reactor and spallation neutron sources; smaller samples and much larger molecular weight protein complexes are now feasible for investigation so as to establish their protonation states and bound water structure. With the X-ray lasers, closely linked to the SR developments, we anticipate the use of ever smaller samples such as nanocrystals, nanoclusters and single molecules, as well as opening up femtosecond time-resolved diffraction structural studies. At the SR sources, a very high throughput assessment for the best crystal samples and tackling sub-micron crystals will become widespread.

On biological signaling

2020 ◽  
Vol 75 (6) ◽  
pp. 507-509 ◽  
Author(s):  
Günter Nimtz ◽  
Horst Aichmann
Keyword(s):  
Phase Transition ◽  
Alternative Model ◽  
Pulse Propagation ◽  
Membrane Surface ◽  
Bound Water ◽  
Theoretical Description ◽  
Lyotropic Liquid Crystal ◽  
Local Phase ◽  
Electric Action ◽  
Nerve Pulse

AbstractPresently, nerve pulse propagation is understood to take place by electric action pulses. The theoretical description is given by the Hodgkin-Huxley model. Recently, an alternative model was proclaimed, where signaling is carried out by acoustic solitons. The solitons are built by a local phase transition in the lyotropic liquid crystal (LLC) of a biologic membrane. We argue that the crystal structure arranging hydrogen bonds at the membrane surface do not allow such an acoustic soliton model. The bound water is a component of the LLC and the assumed phase transition represents a negative entropy step.

scholarly journals SANS quantification of bound water in water-soluble polymers across multiple concentration regimes

Soft Matter ◽  
2021 ◽  
Author(s):  
Helen Yao ◽  
Bradley D. Olsen
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Bound Water ◽  
Water Soluble ◽  
Wide Concentration Range ◽  
Water Molecules ◽  
Water Soluble Polymers ◽  
Soluble Polymers

Small-angle neutron scattering is used to measure the number of bound water molecules associating with three polymers over a wide concentration range. Different fitting workflows are evaluated and recommended depending on the concentration regime.

scholarly journals Characterization of microbial antifreeze protein with intermediate activity suggests that a bound-water network is essential for hyperactivity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
N. M.-Mofiz Uddin Khan ◽  
Tatsuya Arai ◽  
Sakae Tsuda ◽  
Hidemasa Kondo
Keyword(s):  
Crystal Structure ◽  
Basal Plane ◽  
Molecular Mechanisms ◽  
Bound Water ◽  
Hydrophobic Hydration ◽  
Water Network ◽  
Molecular Scaffold ◽  
Intermediate Activity ◽  
Mold Fungus ◽  
Antifreeze Activity

AbstractAntifreeze proteins (AFPs) inhibit ice growth by adsorbing onto specific ice planes. Microbial AFPs show diverse antifreeze activity and ice plane specificity, while sharing a common molecular scaffold. To probe the molecular mechanisms responsible for AFP activity, we here characterized the antifreeze activity and crystal structure of TisAFP7 from the snow mold fungus Typhula ishikariensis. TisAFP7 exhibited intermediate activity, with the ability to bind the basal plane, compared with a hyperactive isoform TisAFP8 and a moderately active isoform TisAFP6. Analysis of the TisAFP7 crystal structure revealed a bound-water network arranged in a zigzag pattern on the surface of the protein’s ice-binding site (IBS). While the three AFP isoforms shared the water network pattern, the network on TisAFP7 IBS was not extensive, which was likely related to its intermediate activity. Analysis of the TisAFP7 crystal structure also revealed the presence of additional water molecules that form a ring-like network surrounding the hydrophobic side chain of a crucial IBS phenylalanine, which might be responsible for the increased adsorption of AFP molecule onto the basal plane. Based on these observations, we propose that the extended water network and hydrophobic hydration at IBS together determine the TisAFP activity.

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