Bacillus subtilis biofilms characterized as hydrogels. Insights on water uptake and water binding in biofilms

Soft Matter ◽  
2020 ◽  
Vol 16 (26) ◽  
pp. 6180-6190 ◽  
Author(s):  
Nir Ido ◽  
Amir Lybman ◽  
Shahar Hayet ◽  
David N. Azulay ◽  
Mnar Ghrayeb ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Water Uptake ◽  
Bound Water ◽  
Swelling Properties ◽  
Water Binding

Bacillus subtilis biofilms resemble cross-linked hydrogels in their morphology and swelling properties. All the water in these biofilms is bound water. Water binding is mostly related with accumulated solutes.

scholarly journals A thermodynamic formulation of root water uptake

2016 ◽  
Vol 20 (8) ◽  
pp. 3441-3454 ◽  
Author(s):  
Anke Hildebrandt ◽  
Axel Kleidon ◽  
Marcel Bechmann
Keyword(s):  
Soil Water ◽  
Water Uptake ◽  
Water Distribution ◽  
Bound Water ◽  
Root Water Uptake ◽  
Flow Path ◽  
Thermodynamic Evaluation ◽  
Entire Flow ◽  
Soil Water Distribution

Abstract. By extracting bound water from the soil and lifting it to the canopy, root systems of vegetation perform work. Here we describe how root water uptake can be evaluated thermodynamically and demonstrate that this evaluation provides additional insights into the factors that impede root water uptake. We derive an expression that relates the energy export at the base of the root system to a sum of terms that reflect all fluxes and storage changes along the flow path in thermodynamic terms. We illustrate this thermodynamic formulation using an idealized setup of scenarios with a simple model. In these scenarios, we demonstrate why heterogeneity in soil water distribution and rooting properties affect the impediment of water flow even though the mean soil water content and rooting properties are the same across the scenarios. The effects of heterogeneity can clearly be identified in the thermodynamics of the system in terms of differences in dissipative losses and hydraulic energy, resulting in an earlier start of water limitation in the drying cycle. We conclude that this thermodynamic evaluation of root water uptake conveniently provides insights into the impediments of different processes along the entire flow path, which goes beyond resistances and also accounts for the role of heterogeneity in soil water distribution.

scholarly journals A Novel Hydrogel Based on Renewable Materials for Agricultural Application

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Silvie Durpekova ◽  
Kateryna Filatova ◽  
Jaroslav Cisar ◽  
Alena Ronzova ◽  
Erika Kutalkova ◽  
...  
Keyword(s):  
Citric Acid ◽  
Water Uptake ◽  
Agricultural Product ◽  
Cellulose Derivatives ◽  
Gravimetric Analysis ◽  
Renewable Materials ◽  
Swelling Properties ◽  
Arable Farming ◽  
Swelling Capacity ◽  
The Stability

This study details the design and characterization of a new, biodegradable, and renewable whey/cellulose-based hydrogel (i.e., agricultural hydrogel). This was formulated from cellulose derivatives (carboxymethylcellulose (CMC) and hydroxyethylcellulose (HEC)) and acid whey cross-linked with citric acid, with the aim to obtain an agricultural product with a high swelling capacity to uphold the quality of soil and conserve water resources. With regard to the swelling behaviour of the prepared hydrogels, the authors initially assessed the swelling ratio and capacity for water uptake. Evaluating the chemical structure of the hydrogel and its thermal and viscoelastic properties involved performing Fourier transform infrared spectroscopy, differential scanning colorimetry, thermal gravimetric analysis, and rheological measurement of the hydrogel films. According to preliminary results, sufficient swelling capacity and stiffness were observed in a hydrogel prepared with 3% CMC and HEC, cross-linked with 5% citric acid. Moreover, the kinetics of water uptake revealed a promising capacity that was sustainable after 5 drying and swelling cycles. The results confirmed that the stability of the hydrogel was enhanced by the presence of the citric acid. As a consequence, it is necessary to utilize an appropriate cross-linking concentration and abide by certain conditions to ensure the swelling properties of the prepared hydrogel are sufficient. Further investigation of the topic, especially in relation to applications in soil, could confirm if the whey-cellulose-based hydrogel is actually suitable for agricultural use, thereby contributing to the advancement of sustainable arable farming.

Dynamic Characterization of the Water Binding Loop in the P-Type Cardiotoxin:  Implication for the Role of the Bound Water Molecule†

Biochemistry ◽  
2001 ◽  
Vol 40 (43) ◽  
pp. 12782-12794 ◽  
Author(s):  
Shih-Che Sue ◽  
Harold C. Jarrell ◽  
Jean-Robert Brisson ◽  
Wen-guey Wu
Keyword(s):  
Water Molecule ◽  
Bound Water ◽  
Dynamic Characterization ◽  
Water Binding ◽  
P Type ◽  
Binding Loop

Two-Phase Hygrothermal Diffusion in an Epoxy Adhesive

2006 ◽  
Vol 258-260 ◽  
pp. 453-460
Author(s):  
Sylvain Popineau ◽  
C. Rondeau-Mouro ◽  
Christine Sulpice-Gaillet ◽  
Martin E.R. Shanahan
Keyword(s):  
Water Uptake ◽  
Bound Water ◽  
Epoxy Adhesive ◽  
Mathematical Treatment ◽  
Water Decomposition ◽  
Two Phase ◽  
Gravimetric Data ◽  
Diffusion In Polymers ◽  
Two Phases ◽  
Mass Increase

Water diffusion in polymers can often be approximated by a Fickian description, but a 2- phase model was proposed some years ago by Carter and Kibler (C&K), often referred to as “Langmuirtype” diffusion, by analogy with the Langmuir theory of adsorption. The two phases in question correspond to “mobile” and “bound” diffusant molecules. In this study, we have considered water uptake in an epoxy resin (an adhesive), employing gravimetry. A good, overall, empirical agreement with the C&K mathematical description of total mass increase with time has been obtained. In many applications of the C&K theory when used to quantify diffusion of water in polymers, only total water uptake is considered as a datum. However, a simple mathematical treatment of the theory enables the separate mobile and bound contributions to be isolated. These supplementary data have been used to try to get a better understanding of the meaning of the terms “mobile” and “bound” phases. Deuterium NMR analysis has been employed to study the mobility of the absorbed water. Decomposition of spectra has permitted us to assign two signals to the fractions of “mobile” and “bound” water. Analysis of peak evolution and a comparison with gravimetric data lead us to suggest that the “mobile” phase corresponds to diffusing molecules, whereas the “bound” phase corresponds to “clusters”.

scholarly journals A thermodynamic formulation of root water uptake

2015 ◽  
Vol 12 (12) ◽  
pp. 13383-13413
Author(s):  
A. Hildebrandt ◽  
A. Kleidon ◽  
M. Bechmann
Keyword(s):  
Root System ◽  
Water Uptake ◽  
Water Distribution ◽  
Bound Water ◽  
Root Water Uptake ◽  
Flow Path ◽  
Thermodynamic Evaluation ◽  
Flux Boundary Condition ◽  
Physically Based ◽  
Energy Domain

Abstract. By extracting bound water from the soil and lifting it to the canopy, root systems of vegetation perform work. Here we describe how the energetics involved in root water uptake can be quantified. The illustration is done using a simple, four-box model of the soil-root system to represent heterogeneity and a parameterization in which root water uptake is driven by the xylem potential of the plant with a fixed flux boundary condition. We use this approach to evaluate the effects of soil moisture heterogeneity and root system properties on the dissipative losses and export of energy involved in root water uptake. For this, we derive an expression that relates the energy export at the root collar to a sum of terms that reflect all fluxes and storage changes along the flow path in thermodynamic terms. We conclude that such a thermodynamic evaluation of root water uptake conveniently provides insights into the impediments of different processes along the entire flow path and explicitly accounting not only for the resistances along the flow path and those imposed by soil drying but especially the role of heterogenous soil water distribution. The results show that least energy needs to be exported and dissipative losses are minimized by a root system if it extracts water uniformly from the soil. This has implications for plant water relations in forests where canopies generate heterogenous input patterns. Our diagnostic in the energy domain should be useful in future model applications for quantifying how plants can evolve towards greater efficiency in their structure and function, particularly in heterogenous soil environments. Generally, this approach may help to better describe heterogeneous processes in the soil in a simple, yet physically-based way.

INFLUENCE OF FRUIT FOOD ADDITIVES ON THE FORMS OF WATER BINDING IN WHEAT FLOUR DOUGH

2020 ◽  
Author(s):  
Е.П. ВИКТОРОВА ◽  
О.В. ФЕДОСЕЕВА ◽  
Т.А. ШАХРАЙ ◽  
Н.Н. КОРНЕН
Keyword(s):  
Wheat Flour ◽  
Food Additives ◽  
Bound Water ◽  
Bound State ◽  
Absorption Capacity ◽  
Water Binding ◽  
Flour Dough ◽  
Wheat Flour Dough ◽  
Fruit Processing ◽  
Relaxation Characteristics

Оценено влияние фруктовых пищевых добавок «Яблочная» и «Грушевая», полученных из вторичных ресурсов переработки фруктов, на формы связи воды в тесте из пшеничной муки. Добавки вносили в образцы теста из пшеничной муки 1-го сорта в количестве 6, 8 и 10% к массе муки. Измерение ядерно-магнитных релаксационных характеристик образцов теста осуществляли на ЯМР-анализаторе АМВ-1006М при температуре 23°С. Установлено, что внесение в образцы теста добавки «Яблочная» или «Грушевая» в количестве 10% к массе муки позволяет повысить содержание прочносвязанной воды в тесте на 6,5 или 4,9% соответственно, что объясняется более высоким содержанием в добавке «Яблочная» по сравнению с добавкой «Грушевая» пектина (3,7% против 2,1%), в значительной степени проявляющего водоудерживающую способность. Результаты, полученные с применением метода ЯМР, согласуются с данными, полученными при исследовании влияния указанных пищевых добавок на водопоглотительную способность теста. Повышение в тесте содержания воды, находящейся в прочносвязанном состоянии, позволит при дальнейшей выпечке тестовых заготовок снизить упек хлебобулочного изделия и, следовательно, увеличить его выход. The influence of fruit food additives «Apple» and «Pear», obtained from secondary resources of fruit processing, on the forms of water connection in the wheat flour dough was evaluated. Additives are added to the test samples from wheat flour of the 1st grade in the amount of 6, 8 and 10% by weight of flour. Measurement of the nuclear magnetic relaxation characteristics of dough samples was performed using an NMR-analyzer AMV-1006M at a temperature of 23°C. It was found that introduction additives «Apple» or «Pear» to the dough samples in an amount of 10% by weight of flour allows increasing the content of strongly bound water in the dough by 6,5 or 4,9% respectively, which is explained by the higher content in additive the «Apple» compared to the additive «Pear» of pectin (3,7% vs. 2,1%), largely showing water-retaining ability. The results obtained using the NMR method are consistent with the data obtained in the study of the effect of these food additives on the water absorption capacity of the dough. Increasing in the dough the content of water, which is in a strongly bound state, will allow for further baking of dough blanks to reduce baking loss and, consequently, increase yield of products.

scholarly journals Measurement and Modelling of Moisture Distribution and Water Binding Energy of Dredged Sludge

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3395
Author(s):  
Feiyan Mao ◽  
Yingjie Zhao ◽  
Yiping Zhang ◽  
Zhou Chen ◽  
Lu Yin
Keyword(s):  
Binding Energy ◽  
Water Distribution ◽  
Bound Water ◽  
Free Water ◽  
Moisture Distribution ◽  
Water Binding ◽  
Dredged Sludge ◽  
Urban Watercourse ◽  
Experimental Values ◽  
Stage 1

The dewatering of dredged sludge is a critical step in the minimization and reutilization of this solid waste. However, there is a lack of available literature on the fundamental drying characteristics of dredged sludge. In this work, two kinds of typical sludge dredged from an urban watercourse were tested by low-field NMR to investigate the water distribution in sludge and it was found that water contained in sludge can be classified into three categories: free water, capillary water and bound water. In addition, a novel model was proposed based on the Lennard-Jones equation and Kelvin law to quantitatively evaluate the binding energy during drying. Further, the model results were experimentally verified by thermogravimetry differential thermal analysis (TG-DTA). Results show that the trends of the model are consistent with the experimental values and the gradient of energy consumption during dehydration can be divided into three main stages. In stage 1, the total energy required for dewatering equals the latent heat of free water. In stage 2, binding energy reaches dozens to hundreds of kJ/kg accounting for capillary action. In stage 3, binding energy increases steeply reaching almost thousands of kJ/kg due to intermolecular interactions. All the discovered aspects could improve the management and disposal of dredged sludge from an energy cost perspective.

scholarly journals QM/MM computational studies of substrate water binding to the oxygen-evolving centre of photosystem II

2007 ◽  
Vol 363 (1494) ◽  
pp. 1149-1156 ◽  
Author(s):  
Eduardo M Sproviero ◽  
Katherine Shinopoulos ◽  
José A Gascón ◽  
James P McEvoy ◽  
Gary W Brudvig ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Exchange Rates ◽  
Water Exchange ◽  
Metal Cluster ◽  
Bound Water ◽  
Water Molecules ◽  
Computational Studies ◽  
Water Binding ◽  
Model Complexes ◽  
Oxygen Evolving

This paper reports computational studies of substrate water binding to the oxygen-evolving centre (OEC) of photosystem II (PSII), completely ligated by amino acid residues, water, hydroxide and chloride. The calculations are based on quantum mechanics/molecular mechanics hybrid models of the OEC of PSII, recently developed in conjunction with the X-ray crystal structure of PSII from the cyanobacterium Thermosynechococcus elongatus . The model OEC involves a cuboidal Mn 3 CaO 4 Mn metal cluster with three closely associated manganese ions linked to a single μ 4 -oxo-ligated Mn ion, often called the ‘dangling manganese’. Two water molecules bound to calcium and the dangling manganese are postulated to be substrate molecules, responsible for dioxygen formation. It is found that the energy barriers for the Mn(4)-bound water agree nicely with those of model complexes. However, the barriers for Ca-bound waters are substantially larger. Water binding is not simply correlated to the formal oxidation states of the metal centres but rather to their corresponding electrostatic potential atomic charges as modulated by charge-transfer interactions. The calculations of structural rearrangements during water exchange provide support for the experimental finding that the exchange rates with bulk 18 O-labelled water should be smaller for water molecules coordinated to calcium than for water molecules attached to the dangling manganese. The models also predict that the S 1 →S 2 transition should produce opposite effects on the two water-exchange rates.

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