scholarly journals Biodegradable Hydrogels: Evaluation of Degradation as a Function of Synthesis Parameters and Environmental Conditions

Soil Systems ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 47
Author(s):  
Chiara Turioni ◽  
Giacomo Guerrini ◽  
Andrea Squartini ◽  
Francesco Morari ◽  
Michele Maggini ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Decisive Role ◽  
Environmental Parameters ◽  
Functional Materials ◽  
Crosslinking Degree ◽  
Swelling Degree ◽  
Biodegradable Hydrogels ◽  
Synthesis Parameters

The development of functional materials that promote the infiltration and retention of water and the controlled release of fertilizers and nutrients in soil is of interest in agriculture. In this context, hydrogels, three-dimensional polymeric structures able to absorb high amounts of water in their swelling process, play an important role. The swelling ability of hydrogels depends on their crosslinking: the higher the crosslinking degree, the higher the number of interactions in the structure, the lower the swelling response. In this work, we describe biodegradable hydrogels composed of natural feedstocks: cellulose, clay minerals, and humic acids, designed to (i) protect, hydrate, and help germinating seedlings to root even in unfavorable conditions; (ii) sustainably contribute to soil fertility in terms of moisture and nutrients; and (iii) act as a nutritive and protective coating for the seeds. Upon assessing the correlations between curing process and swelling degree (SW), we evaluated the degradation of new biodegradable hydrogels as a function of the synthesis parameters (swelling degree and composition) and environmental conditions (type of soil and water amount for the hydration of the hydrogels). The term curing is hereafter referred to the operation of baking the ingredients at given combinations of time and temperature to obtain a dry hydrogel. The results show that the environmental parameters considered, i.e., amount of hydration water and physical and chemical properties of the soil, play a more decisive role in determining the stability of these hydrogels in soil than their synthesis parameters, such as the composition and the swelling degree.

Innovative techniques to improve cyanobacterial survival and growth in inoculated dryland soils

2021 ◽  
Author(s):  
Lisa Maggioli ◽  
Aitor Alameda ◽  
Jose Raúl Román ◽  
Sonia Chamizo ◽  
Carlotta Pagli ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Chlorophyll A ◽  
Environmental Conditions ◽  
Abiotic Stresses ◽  
Wind Erosion ◽  
Soil Stabilization ◽  
Chemical Properties ◽  
Decisive Role ◽  
Terrestrial Ecosystems ◽  
Chlorophyll A Content

<p>Nowadays, land use change and the impacts of climate change are accelerating land degradation processes in drylands. These regions occupy around 40% of the Earth land’s surface and their extension is likely to represent around 45% by 2050. Biocrusts (complex communities formed by bacteria, cyanobacteria, microalgae, fungi, lichens and mosses which live in the uppermost layer of soil and can cover up to 70% of the interplant areas) play a decisive role in soil stabilization and fertility in these regions, so that they have been proposed as restoration agents in degraded dryland sites, where water scarcity and the harsh environmental conditions can hinder traditional restoration based on the use of vegetation establishment. Within the different biocrust-forming organisms, the use of cyanobacteria as a biotechnological tool to combat soil degradation, is gaining increasing importance. Cyanobacteria are the pioneer colonizers of terrestrial ecosystems, they are able to resist extreme environmental conditions, i.e. high temperatures, prolonged UV radiation and nutrients scarcity. At the same time, they improve physical-chemical properties of the soil by fixing carbon and many species also the atmospheric nitrogen and by producing exopolysaccharides that strongly increase soil stability and eventually creating a more favorable environment for colonization by other organisms. Despite several laboratory studies demonstrate the effectiveness of inoculating soil with cyanobacteria and their effect in increasing soil carbon and nutrient content, few field studies are available and many of them show a limited success probably because of the harsh environmental conditions that hamper an optimal growth. In the present work, soils collected from different ecosystems  in SE Spain were inoculated with a consortium of four native cyanobacteria species: Nostoc comune, Trichocoleus desertorum, Tolypothrix distorta and Leptolyngbia sp., and  different techniques to reduce abiotic stresses were tested in outdoors conditions: 1) cyanobacteria + soil covered with a mesh made of Stipa tenacissima, 2) cyanobacteria+ Plantago-based stabilizer amendment, and 3) cyanobacteria + sewage sludge (incorporated as an organic amendment) . The application of plant-based ameliorating strategies resulted in a higher chlorophyll a content, which reflects an improvement of cyanobacterial growth compared to the inoculation lacking the application of ameliorating techniques. The soil albedo also decreased due to surface darkening, thus also indicating a higher cyanobacterial growth in these treatments. Wind tunnel experiments also demonstrated a lower susceptibility to wind erosion in the cyanobacteria-inoculated soils combined with application of the plant mesh or the Plantago amendment. These results highlight the importance of using plant-based amelioration techniques to reduce abiotic stresses, especially in the early stages of soil colonization after cyanobacteria inoculation. Regarding the use of sewage sludge, it was demonstrated that their application at low doses improved cyanobacteria growth, which was reflected in an increase in chlorophyll a content as well as in a significant increase of aggregate stability and reduced soil susceptibility to wind erosion. This study shows promising results to enhance cyanobacterial growth and prevent cyanobacteria inoculum loss under natural conditions. Ongoing experiments will evaluate the effectiveness of these strategies under field conditions.</p>

Smart Hydrogels for Pharmaceutical Applications

2017 ◽  
pp. 1133-1164
Author(s):  
Snežana S. Ilić-Stojanović ◽  
Ljubiša B. Nikolić ◽  
Vesna D. Nikolić ◽  
Slobodan D. Petrović
Keyword(s):  
Electric Fields ◽  
Polymer Network ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Stimuli Responsive ◽  
Crosslinking Degree ◽  
Color Transparency ◽  
Hydrogel Network ◽  
Physical And Chemical ◽  
Responsive Hydrogels

The latest development in the field of smart hydrogels application as drugs carriers is shown in this chapter. Hydrogels are three-dimensional polymer network consisting of at least one hydrophilic monomer. They are insoluble in water, but in the excess presence of water or physiological fluids, swell to the equilibrium state. The amount of absorbed water depends on the chemical composition and the crosslinking degree of 3D hydrogel network and reaches over 1000% of the xerogel weight. Stimuli-responsive hydrogels exhibit significant change of their properties (swelling, color, transparency, conductivity, shape) due to small changes in the external environment conditions (pH, ionic strength, temperature, light wavelength, magnetic or electric fields, ultrasound, or a combination thereof). This smart hydrogels, with different physical and chemical properties, chemical structure and technology of obtaining, show great potential for application in the pharmaceutical industry. The application of smart hydrogels is very promising and at the beginning of the development and exploitation.

scholarly journals Ethylene glycol assisted three-dimensional floral evolution of BiFeO 3 -based nanostructures with effective magneto-electric response

2020 ◽  
Vol 7 (8) ◽  
pp. 200642
Author(s):  
Syed Kumail Abbas ◽  
Ghulam M. Mustafa ◽  
Murtaza Saleem ◽  
Muhammad Sufyan ◽  
Saira Riaz ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Self Assembly ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Functional Materials ◽  
Bias Field ◽  
Memory Storage ◽  
High Coercivity ◽  
Electric Response ◽  
Ferromagnetic Behaviour

Controlled growth of nanostructures plays a vital role in tuning the physical and chemical properties of functional materials for advanced energy and memory storage devices. Herein, we synthesized hierarchical micro-sized flowers, built by the self-assembly of highly crystalline, two-dimensional nanoplates of Co- and Ni-doped BiFeO 3 , using a simple ethylene glycol-mediated solvothermal method. Pure BiFeO 3 attained scattered one-dimensional nanorods-type morphology having diameter nearly 60 nm. Co-doping of Co and Ni at Fe-site in BiFeO 3 does not destabilize the morphology; rather it generates three-dimensional floral patterns of self-assembled nanoplates. Unsaturated polarization loops obtained for BiFeO 3 confirmed the leakage behaviour of these rhombohedrally distorted cubic perovskites. These loops were then used to determine the energy density of the BiFeO 3 perovskites. Enhanced ferromagnetic behaviour with high coercivity and remanence was observed for these nanoplates. A detailed discussion about the origin of ferromagnetic behaviour based on Goodenough–Kanamori's rule is also a part of this paper. Impedance spectroscopy revealed a true Warburg capacitive behaviour of the synthesized nanoplates. High magneto-electric (ME) coefficient of 27 mV cm −1 Oe −1 at a bias field of −0.2 Oe was observed which confirmed the existence of ME coupling in these nanoplates.

Smart Hydrogels for Pharmaceutical Applications

2017 ◽  
pp. 278-310 ◽  
Author(s):  
Snežana S. Ilić-Stojanović ◽  
Ljubiša B. Nikolić ◽  
Vesna D. Nikolić ◽  
Slobodan D. Petrović
Keyword(s):  
Electric Fields ◽  
Polymer Network ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Stimuli Responsive ◽  
Crosslinking Degree ◽  
Color Transparency ◽  
Hydrogel Network ◽  
Physical And Chemical ◽  
Responsive Hydrogels

The latest development in the field of smart hydrogels application as drugs carriers is shown in this chapter. Hydrogels are three-dimensional polymer network consisting of at least one hydrophilic monomer. They are insoluble in water, but in the excess presence of water or physiological fluids, swell to the equilibrium state. The amount of absorbed water depends on the chemical composition and the crosslinking degree of 3D hydrogel network and reaches over 1000% of the xerogel weight. Stimuli-responsive hydrogels exhibit significant change of their properties (swelling, color, transparency, conductivity, shape) due to small changes in the external environment conditions (pH, ionic strength, temperature, light wavelength, magnetic or electric fields, ultrasound, or a combination thereof). This smart hydrogels, with different physical and chemical properties, chemical structure and technology of obtaining, show great potential for application in the pharmaceutical industry. The application of smart hydrogels is very promising and at the beginning of the development and exploitation.

An innovative experimental device to assess the behavior of a chemical under controlled environmental parameters

2017 ◽  
Vol 2017 (1) ◽  
pp. 1287-1303
Author(s):  
William Giraud ◽  
Amélie Thomas ◽  
Pierre Richard ◽  
Sophie Chataing ◽  
Stéphane Le Floch
Keyword(s):  
Environmental Conditions ◽  
Salt Water ◽  
Chemical Properties ◽  
Environmental Parameters ◽  
Experimental Device ◽  
Global Knowledge ◽  
Short Term ◽  
Specific Chemical ◽  
Water Compartments ◽  
Wide Range

Abstract (ID 2017-381) Knowledge of the behavior of HNS (Hazardous and Noxious Substances) spilled into the aquatic environment is essential to define appropriate response actions; e.g. deployment of efficient equipment and activation of appropriate procedures. As a first approach, the Standard European Behaviour Classification (SEBC) may be used to acquire global knowledge of the short-term behavior of the chemical spilled, taking into account its basic physical and chemical properties (density, solubility and vapor pressure). However, the SEBC presents several limitations. Indeed, the competition between mass transfer processes (evaporation, dissolution, etc.) is not considered when the behavior of the chemical is theoretically determined from its physical chemical properties alone. Moreover, these measurements are made in standardized conditions (e.g. temperature of 20°C, freshwater) while, depending on its nature, the behavior of a chemical can greatly vary with temperature (e.g. palm oil may be solid under about 25°C) and other environmental parameters (velocity of wind, salinity and suspended matter in the water, etc.). To tackle these issues, Cedre has developed an experimental device able to rapidly determine the behavior of a chemical under some specific environmental conditions. It is composed of a 80 L tank, specially equipped with a wind generator and a lamp, in order to reproduce some critical environmental parameters: water temperature, velocity of wind and solar radiation. After pouring the chemical onto the surface of the fresh or salt water, under the fixed controlled parameters mentioned above, the concentration of the studied chemical is monitored over time, in both the air and water compartments. These measurements can be used to characterize the short-term behavior of a chemical in specific controlled conditions and thus to compare it to the behavior estimated from the SEBC. Such a tool could be of a considerable interest for responders. In the framework of the preparation of contingency plans, the response to a specific chemical can be optimized by performing experimentations covering a wide range of environmental conditions. In the event of a spill, specific conditions can be immediately reproduced to support responders and authorities who may have to take strategic decisions. The whole experimental device will be presented, including the tools and procedures to reproduce the environmental conditions. Then, initial results obtained with different chemicals will be presented.

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