scholarly journals A universal method to easily design tough and stretchable hydrogels

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Chisa Norioka ◽  
Yuino Inamoto ◽  
Chika Hajime ◽  
Akifumi Kawamura ◽  
Takashi Miyata
Keyword(s):  
Energy Dissipation ◽  
Polymer Chain ◽  
Mechanical Performance ◽  
Monomer Concentration ◽  
High Water ◽  
High Water Content ◽  
Universal Method ◽  
Covalent Bonds ◽  
Physical And Chemical ◽  
Chain Entanglements

AbstractHydrogels are flexible materials that have high potential for use in various applications due to their unique properties. However, their applications are greatly restricted by the low mechanical performance caused by high water content and inhomogeneous networks. This paper reports a universal strategy for easily preparing hydrogels that are tough and stretchable without any special structures or complicated processes. Our strategy involves tuning the polymerization conditions to form networks with many polymer chain entanglements to achieve energy dissipation. Tough and stretchable hydrogels can be prepared by free radical polymerization with a high monomer concentration and low cross-linker content to optimize the balance between physical and chemical cross-links by entanglements and covalent bonds, respectively. The strategy of using polymer chain entanglements for energy dissipation allows us to overcome the limitation of low mechanical performance, which leads to the wide practical use of hydrogels.

Preparation and characterization of modified chitosan for in vitro controlled release of vitamin B12

2013 ◽  
Vol 33 (8) ◽  
pp. 757-765 ◽  
Author(s):  
Ahmed Awadallah-F ◽  
Tahia B. Mostafa
Keyword(s):  
Water Content ◽  
Monomer Concentration ◽  
High Water ◽  
High Water Content ◽  
Vitamin B ◽  
Acryloyl Chloride ◽  
Modified Chitosan ◽  
Increase With Increase

Abstract Graft copolymerization of acrylonitrile and acryloyl chloride on to chitosan was prepared by γ-rays. Optimization of the grafting (%) was studied. The grafting (%) was observed to increase with increase in the irradiation dose and monomer concentration. The grafting percentages were about 52% and 36% from polyacrylonitrile and poly(acryloyl chloride), respectively. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the specimens. The modified chitosan was loaded with vitamin B12, demonstrated nearly 5.0±2.3% and 50.1±4.5% release in the media of pH 1.2 and 6.8, respectively, for amidoximated chitosan-grafted polyacrylonitrile and 3.6±1.1% and 36±2.4% in pH 1.2 and 6.8, respectively, for chitosan-grafted poly(acryloyl chloride), as determined by a traditional dissolution model. The modified chitosan specimens that uploaded with vitamin B12 displayed a more decremental release in the acidic medium than the neutral one. However, in order to incorporate in vivo gastrointestinal conditions, such as acidic pH and high water content in the stomach, low water content, and the presence of semi-solid mass in the large intestine, a new model, called flow through diffusion cell, was also used to study the drug release. The results of the two approaches produced different release profiles at the same pH values.

Characterization of Automotive Paint Sludge (APS) for Chemical/Energy Recovery via Microwave Assisted Pyrolysis

2015 ◽  
Vol 1113 ◽  
pp. 236-241 ◽  
Author(s):  
Zakiuddin Januri ◽  
Norazah Abdul Rahman ◽  
Siti Shawalliah Idris ◽  
Sharmeela Matali ◽  
Shareena Fairuz Abdul Manaf
Keyword(s):  
Energy Recovery ◽  
Chemical Characterization ◽  
High Water ◽  
Volatile Matter ◽  
High Water Content ◽  
Microwave Assisted ◽  
Automotive Paint ◽  
Paint Sludge ◽  
Physical And Chemical

This paper reported on the characterization of the Automotive Paint Sludge (APS) via several characterisation technique. It is an essential to search the physical and chemical characterization of the automotive paint sludge sample for further microwave assisted pyrolysis experiment for chemical and energy recovery from APS. APS contains about 2.9%, 2.4%, 75.9% and 3.2% of ash, moisture, volatile matter and fixed carbon content respectively. Both wet and dried APS samples show similar FTIR peak at the hydrocarbon region while wet sample have high water content. Meanwhile zero moisture (ZM) sample loss almost 90% of its content on the hydrocarbon. This shows that wet automotive paint sludge samples can be used in the microwave pyrolyzer without any pretreatment and the water can act as an absorbance to microwave radiation. While APS itself contains about 22.6 MJkg-1of energy. Furthermore, melting temperature of automotive paint sludge are in the range of 260 °C to 500 °C with the enthalpy in the range of 40 J/g to 300 J/g. Chemical composition of APS for all three conditions can be described as C38H10N9S, C102H9N21S and C85H8N21S for wet sample, open air dry sample and zero moisture sample respectively.

scholarly journals Adsorption isotherms of the red mombin powder produced in spouted bed dryer

2017 ◽  
Vol 21 (8) ◽  
pp. 562-567 ◽  
Author(s):  
Analha D. F. Lins ◽  
Ana P. T. Rocha ◽  
Josivanda P. Gomes ◽  
Regilane M. Feitosa ◽  
Gilmar T. Araujo ◽  
...  
Keyword(s):  
Experimental Data ◽  
Spherical Shape ◽  
High Water ◽  
High Water Content ◽  
Spouted Bed ◽  
Degradation Reactions ◽  
Hausner Ratio ◽  
Powder Particles ◽  
Hygroscopic Behavior ◽  
Physical And Chemical

ABSTRACT Red mombin is a seasonal fruit and susceptible to degradation reactions due to its high water content. This highlights the need to use processes that prolong its life and make it available all year round, including to markets away from the production sites. Thus, the objective of this study was to produce red mombin pulp powder in spouted bed dryer, evaluate it regarding physical and chemical parameters and assess its hygroscopic behavior at temperatures of 20, 30 and 40 °C, fitting the models of the GAB, Oswin and Peleg to the experimental data. The results of the physical and chemical analyses showed intermediate wetting time of 0.39 g min-1, solubility higher than 60% and mean flowability with Hausner ratio and Carr index of 1.26-1.34 and 0.21-0.25, respectively. The powder particles exhibited spherical shape, smooth surface and some irregularities, with tendency to form agglomerates. The isotherms had a type-II sigmoidal behavior, and the Peleg model, at all temperatures, showed the best fits to the experimental data with determination coefficients above 0.99 and mean percentage deviations lower than 2.0%.

Characteristics of sediments from a stormwater management pond

1997 ◽  
Vol 36 (8-9) ◽  
pp. 117-122 ◽  
Author(s):  
J. Marsalek ◽  
P. M. Marsalek
Keyword(s):  
Water Content ◽  
Urban Areas ◽  
Sequential Analysis ◽  
High Water ◽  
High Water Content ◽  
Sediment Depth ◽  
Mobile Forms ◽  
Stormwater Pond ◽  
Physical And Chemical ◽  
Distribution Water

Physical and chemical characteristics of bottom sediment from an on-stream stormwater pond were described by the depth of sediment accumulations, particle size distribution, water content, concentrations of total metals, and distribution of metal fractions determined by a sequential analysis. Except for a sand/gravel spit by the creek inflow, bottom sediments comprised silt and clay, with high water content (up to 80%, by volume), and accumulated at a rate of 0.02 m·yr−1 (bulk sediment depth). Sediments contained elevated levels of heavy metals, among which the levels of Cr, Cu and Pb caused the greatest environmental concerns. Furthermore, sequential analysis indicated that up to 70 - 90% of total metals in these sediment was in potentially mobile forms. Without further treatment, these sediments could not be reused in urban areas, nor readily disposed at municipal landfills.

scholarly journals COMPOSIÇÃO FÍSICO-QUÍMICA, QUALIDADE FÍSICA E SENSORIAL DE CHIPS DE MANDIOQUINHA-SALSA

2013 ◽  
Vol 1 (2) ◽  
Author(s):  
Joao Borges ◽  
Claudia De Paula ◽  
Monica Pirozi
Keyword(s):  
Raw Materials ◽  
Age Groups ◽  
High Water ◽  
Raw Material ◽  
High Water Content ◽  
Mountain Ranges ◽  
Native Culture ◽  
Frying Process ◽  
Solids Content ◽  
Physical And Chemical

The arracacha (Arracacia xanthorrhiza Bancroft.) is a native culture of the Andean mountain ranges, the main types of processing the production of dehydrated mashed, flakes, flour, starch, pre-cooked, among others. The term chips is originally American and refers to thin slices of potato fried in oil or fat may be added various flavors late in the process. The aim of this work was to determine the physical and chemical composition, physical and sensory quality of fried chips of arracacha. The results showed that the root in nature has a high water content (73.51%), which together with microbiological and physical injuries, contributing to the reduction of its shelf life. However its solids content (26.4%) favored the production of fried chips, no significant changes were observed in the color parameters L * a * b * of ready compared to the raw material in nature, indicating minimal changes resulting from frying process. Although the fried chips has presented firmer texture when compared to the same product from raw materials similar in the scientific literature, this result did not influence the uptake by consumers whose scores for flavor, appearance, flavor and texture ranged 7-8, concerning hedonic terms "like moderately" and "liked" both to consumers male and female in age groups studied (10-50 years). The processing of root arracacha to obtain fried chips was promising for commercialization by their acceptance and purchase intent.

scholarly journals Physical and Mechanical Performance of Frozen Rocks and Soil in Different Regions

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Junhao Chen ◽  
Lexiao Wang ◽  
Zhaoming Yao
Keyword(s):  
Mechanical Performance ◽  
Failure Strain ◽  
High Strength ◽  
Cohesive Soil ◽  
High Water ◽  
Curing Temperature ◽  
High Water Content ◽  
Jurassic Rocks ◽  
Frozen Wall ◽  
Rock And Soil

The artificial freezing method is extensively used in the reinforcement of engineering strata in various regions for shaft excavation and subway connection channels. In this study, representative rock and soil strata from different regions were subjected to low-temperature physical and mechanical performance tests. The results show that, compared with Cretaceous and Jurassic rock and soil strata, deep topsoil and shallow coastal topsoil have high water content, low thermal conductivities, high frost heave rates, and high freezing temperatures. In addition, the results show that, as the curing temperature decreases, the uniaxial compressive strengths and elastic moduli of deep topsoil and shallow coastal topsoil increase almost linearly. The strength of the sandy soil strata is the highest, followed by the cohesive soil strata, and the strength of the mucky soil and the calcareous clay is the lowest. The strength of the frozen wall and the waterproof requirements must both be taken into account in the freezing design. Deep Cretaceous and Jurassic rocks can have high strength of more than 5 MPa under normal temperature conditions. An increase in the uniaxial compressive strength and elastic modulus with decreasing curing temperature is mainly manifested within the range from the normal temperature to −10°C. The strength can reach more than 10 MPa at −10°C, and only the strength requirements of the frozen wall need to be considered in the freezing design. At low temperatures, deep topsoil and shallow coastal topsoil are dominated by the form of compression failure. The average failure strain at −10°C is typically greater than 5%. When excavating the strata, it is essential to pay attention to the effect of creep. The failure strain of deep Cretaceous and Jurassic rocks is between 1% and 2%, and the breaking and sudden collapse of surrounding rocks should be prevented.

Features of spring feeding of sterlet of the middle course of the Northern Dvina river

2020 ◽  
pp. 8-17
Author(s):  
A. Bykov ◽  
D. Palatov ◽  
I. Studenov ◽  
D. Chupov
Keyword(s):  
Benthic Communities ◽  
High Water ◽  
Food Composition ◽  
Fish Growth ◽  
High Water Content ◽  
Feeding Intensity ◽  
Biting Midges ◽  
Size Groups ◽  
Main Components ◽  
A Minor

The article provides information about the features of spring feeding of sterlet in the spawning grounds of the middle course of the Northern Dvina river in may 2019. The main and secondary groups of forage objects in the diet of this species of sturgeon are characterized. The article considers the variability of the sterlet food composition with an increase in the size of fish from 30 to 60 cm. In the process of fish growth in the diet of the Severodvinsk sterlet, the main components in terms of occurrence and mass in all size groups are the larvae of Brooks and chironomids. A minor occurrence was the larvae of midges, biting midges, stoneflies, mayflies and small clams. To random and seasonal food are the larvae of water bugs, butterflies, flies, beetles and eggs of other fish. The feeding intensity of the smaller sterlet (30–40 cm) was significantly higher than that of the fish in the size groups 40–50 and 50–60 cm. Fundamental changes in the diet of the Severodvinsk sterlet for the main food objects for more than sixty years of observations have not been established. During periods of high water content of the Northern Dvina due to seasonal changes in the structure of benthic communities, the value of Brooks in the diet of sterlet increases and the proportion of chironomids decreases.

Hydrogels as Antibacterial Biomaterials

2018 ◽  
Vol 24 (8) ◽  
pp. 843-854 ◽  
Author(s):  
Weiguo Xu ◽  
Shujun Dong ◽  
Yuping Han ◽  
Shuqiang Li ◽  
Yang Liu
Keyword(s):  
Mechanical Properties ◽  
Drug Delivery ◽  
Tissue Engineering ◽  
Water Content ◽  
Oxygen Permeability ◽  
Structural Diversity ◽  
High Water ◽  
Clinical Applications ◽  
High Water Content ◽  
Biomedical Field

Hydrogels, as a class of materials for tissue engineering and drug delivery, have high water content and solid-like mechanical properties. Currently, hydrogels with an antibacterial function are a research hotspot in biomedical field. Many advanced antibacterial hydrogels have been developed, each possessing unique qualities, namely high water swellability, high oxygen permeability, improved biocompatibility, ease of loading and releasing drugs and structural diversity. In this article, an overview is provided on the preparation and applications of various antibacterial hydrogels. Furthermore, the prospects in biomedical researches and clinical applications are predicted.

Microwave-Induced Thermoacoustic Imaging for Embedded Explosives Detection in High-Water Content Medium

2019 ◽  
Vol 67 (7) ◽  
pp. 4803-4810 ◽  
Author(s):  
Xiong Wang ◽  
Tao Qin ◽  
Yexian Qin ◽  
Ahmed H. Abdelrahman ◽  
Russell S. Witte ◽  
...  
Keyword(s):  
Water Content ◽  
High Water ◽  
Explosives Detection ◽  
High Water Content ◽  
Thermoacoustic Imaging

scholarly journals Chemical and physical interactions of regenerated cellulose yarns and isocyanate-based matrix systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bernhard Ungerer ◽  
Ulrich Müller ◽  
Antje Potthast ◽  
Enrique Herrero Acero ◽  
Stefan Veigel
Keyword(s):  
Mechanical Performance ◽  
Tensile Force ◽  
Tensile Modulus ◽  
Tensile Tests ◽  
Size Exclusion ◽  
Regenerated Cellulose ◽  
Hydrolytic Cleavage ◽  
Yarn Twist ◽  
Exclusion Chromatography ◽  
Physical And Chemical

AbstractIn the development of structural composites based on regenerated cellulose filaments, the physical and chemical interactions at the fibre-matrix interphase need to be fully understood. In the present study, continuous yarns and filaments of viscose (rayon) were treated with either polymeric diphenylmethane diisocyanate (pMDI) or a pMDI-based hardener for polyurethane resins. The effect of isocyanate treatment on mechanical yarn properties was evaluated in tensile tests. A significant decrease in tensile modulus, tensile force and elongation at break was found for treated samples. As revealed by size exclusion chromatography, isocyanate treatment resulted in a significantly reduced molecular weight of cellulose, presumably owing to hydrolytic cleavage caused by hydrochloric acid occurring as an impurity in pMDI. Yarn twist, fibre moisture content and, most significantly, the chemical composition of the isocyanate matrix were identified as critical process parameters strongly affecting the extent of reduction in mechanical performance. To cope with the problem of degradative reactions an additional step using calcium carbonate to trap hydrogen ions is proposed.

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