scholarly journals Swelling of Hydrogels Based on Carboxymethylated Starch and Poly(Acrylic Acid): Nonlinear Rheological Approach

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2564
Author(s):  
Grzegorz Kowalski ◽  
Paweł Ptaszek ◽  
Łukasz Kuterasiński
Keyword(s):  
Acrylic Acid ◽  
Aqueous Environment ◽  
Large Amplitude Oscillatory Shear ◽  
Gel Structure ◽  
Swelling Behaviour ◽  
Molar Ratios ◽  
Modified Starches ◽  
High Amylose ◽  
Covalent Interactions

In this paper, the authors discuss the results of research on the preparation and properties of superabsorbent hydrogels based on carboxymethylated high-amylose corn starches. They were obtained by graft copolymerisation (in an aqueous environment) of acrylic acid and its sodium salt onto modified starches (with various substitution degrees DS = 0.2 and 0.8), using potassium persulfate as an initiator and N,N’-methylenebisacrylamide (MBA) as a cross-linker. Modified starches, with various DS, were used to synthesise two series of hydrogels with varying molar ratios of cross-linkers to monomers. The swelling behaviour of hydrogels was studied and their properties were estimated using the kinetic equation. The occurrence of starch–polyacrylic acid covalent interactions was demonstrated by FTIR analysis. Nonlinear rheological methods have proved to be very effective in assessing the mechanical properties of hydrogels. LAOS (large -amplitude oscillatory shear) analysis allowed the determination of the durability of the gel structure as a function of the amount of absorbed water.

scholarly journals EXAFS Determination of Clay Minerals in Martian Meteorite Allan Hills 84001 and Its Implication for the Noachian Aqueous Environment

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 176
Author(s):  
Ryoichi Nakada ◽  
Gaku Tanabe ◽  
Iori Kajitani ◽  
Tomohiro Usui ◽  
Masashi Shidare ◽  
...  
Keyword(s):  
Silica Glass ◽  
Large Body ◽  
Aqueous Environment ◽  
Martian Surface ◽  
Exafs Analysis ◽  
Martian Meteorite ◽  
Fe Species ◽  
Allan Hills 84001 ◽  
X Ray Absorption

The aqueous environment of ancient Mars is of significant interest because of evidence suggesting the presence of a large body of liquid water on the surface at ~4 Ga, which differs significantly from the modern dry and oxic Martian environment. In this study, we examined the Fe-bearing minerals in the 4 Ga Martian meteorite, Alan Hills (ALH) 84001, to reveal the ancient aqueous environment present during the formation of this meteorite. Extended X-ray absorption fine structure (EXAFS) analysis was conducted to determine the Fe species in ALH carbonate and silica glass with a high spatial resolution (~1–2 μm). The μ-EXAFS analysis of ALH carbonate showed that the Fe species in the carbonate were dominated by a magnesite-siderite solid solution. Our analysis suggests the presence of smectite group clay in the carbonate, which is consistent with the results of previous thermochemical modeling. We also found serpentine in the silica glass, indicating the decrease of water after the formation of carbonate, at least locally. The possible allochthonous origin of the hematite in the carbonate suggests a patchy redox environment on the ancient Martian surface.

Preparation and characterization of a novel pH-sensitive Salecan-g-poly(acrylic acid) hydrogel for controlled release of doxorubicin

2015 ◽  
Vol 3 (13) ◽  
pp. 2685-2697 ◽  
Author(s):  
Xinyu Hu ◽  
Wei Wei ◽  
Xiaoliang Qi ◽  
Hao Yu ◽  
Liandong Feng ◽  
...  
Keyword(s):  
Controlled Release ◽  
Acrylic Acid ◽  
Ph Sensitive ◽  
Swelling Behaviour ◽  
Poly Acrylic Acid

The pH-sensitive swelling behaviour and DOX release of Salecan-g-PAA hydrogels are discussed.

scholarly journals Breeding of maize types with specific traits at the Maize Research Institute, Zemun Polje

Genetika ◽  
2007 ◽  
Vol 39 (2) ◽  
pp. 169-180 ◽  
Author(s):  
Zorica Pajic
Keyword(s):  
Energy Crop ◽  
Maize Hybrids ◽  
High Lysine ◽  
Breeding Programmes ◽  
Selection For ◽  
High Amylose ◽  
Harvest Maturity ◽  
Maize Research Institute ◽  
Research Institute

Maize is primarily grown as an energy crop, but the use of different specific versions, such as high-oil maize, high-lysine maize, waxy maize, white-seeded maize, popping maize and sweet maize, is quite extensive. Speciality maize, due to its traits and genetic control of these traits, requires a particular attention in handling breeding material during the processes of breeding. It is especially related to prevention of uncontrolled pollination. In order to provide successful selection for a certain trait, the following specific procedures in evaluation of the trait are necessary: the estimation of a popping volume and flake quality in popping maize; the determination of sugars and harvest maturity in sweet maize; the determination of oil in selected samples of high-oil maize types, and so forth. Breeding programmes for speciality maize, except high-amylose maize, have been implemented at the Maize Research Institute, Zemun Polje, Belgrade, for the last 45 years. A great number of high-yielding sweet maize hybrids, popping maize, high-oil and high-lysine, flint and white-seeded maize hybrids were developed during this 45-year period. Auspicious selection and breeding for these traits is facilitated by the abundant genetic variability and technical and technological possibilities necessary for successful selection.

Determination of the formaldehyde-to-phenol molar ratios of resol resins by infrared spectroscopy and multivariate analysis

2003 ◽  
Vol 89 (13) ◽  
pp. 3582-3586 ◽  
Author(s):  
Hilkka Holopainen ◽  
Leila Alvila ◽  
Tuula T. Pakkanen ◽  
Jouni Rainio
Keyword(s):  
Multivariate Analysis ◽  
Infrared Spectroscopy ◽  
Molar Ratios

DESCRIPTION OF CHITOSANE GRAFTED ACRYLIC ACID BASED HYDROGEL SWELLING KINETICS AND THEIR USE IN NEW DESIGNED SYSTEM

2021 ◽  
Author(s):  
Tamara Erceg ◽  
◽  
Gaja Brakus ◽  
Dejan Kojić ◽  
Nevena Vukić ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Room Temperature ◽  
Cost Effective ◽  
Swelling Kinetics ◽  
Swelling Ratio ◽  
Empirical Dependence ◽  
Step Procedure ◽  
Dynamic Swelling ◽  
Hydrogel Swelling

Chitosan based hydrogel was synthesized via free-radical polymerization in a two-step procedure, after modification of chitosan by acrylic acid. Dynamic swelling test was carried out in distilled water at room temperature. Swelling kinetics was modeling using the principle of assuming the equation for a swelling ratio-time empirical dependence. Using regression analysis in this way gives the possibility for simpler determination of swelling ratio-time empirical dependence, knowing the graph functions. Obtained hydrogel was used for preparation of new bilayer hydrogel system which has potential application in wound dressing systems and other fields where pH sensitivity and improved mechanical properties of biopolymers are required in framework of green, cost-effective process.

scholarly journals Potato and high-amylose maize starches are not equivalent producers of butyrate for the colonic mucosa

2000 ◽  
Vol 84 (5) ◽  
pp. 689-696 ◽  
Author(s):  
Lucile J. M. Martin ◽  
Henri J. W. Dumon ◽  
Gérard Lecannu ◽  
Martine M. J. Champ
Keyword(s):  
Colonic Mucosa ◽  
Potato Starch ◽  
Portal Blood Flow ◽  
Short Chain Fatty Acids ◽  
Portal Blood ◽  
Maize Starch ◽  
Catheterization Technique ◽  
High Amylose

Portal appearance of short-chain fatty acids (SCFA) produced from fermentation of three different resistant starch (RS) sources (raw potato starch, high-amylose maize starch and retrograded high-amylose maize starch) was investigated in pigs. The catheterization technique coupled with determination of portal blood flow was used to estimate SCFA uptake by the colonic mucosa. Our hypothesis was that these three RS were not equivalent butyrate providers for the colonic mucosa and that butyrate uptake would therefore be different after in vivo fermentation of each starch. The starches induced different patterns of appearance of SCFA in the portal blood; raw potato starch was the only RS source to show a significant appearance of butyrate in the portal blood. Thus, uptake of butyrate by the colonic mucosa apparently differed between starches. This finding suggests that butyrate uptake does not only depend on the flow of butyrate appearing in the lumen. Indeed, for unexplained reasons, utilization of butyrate by the colonic mucosa appeared to be less efficient when the butyrate was produced from fermentation of potato starch than when it was produced from fermentation of the other RS sources.

Highly Sensitive Electrochemical Determination of Norepinephrine Using Poly Acrylic Acid‐Coated Nanoceria

2019 ◽  
Vol 6 (17) ◽  
pp. 4666-4673 ◽  
Author(s):  
Seong Eun Son ◽  
Euna Ko ◽  
Van‐Khue Tran ◽  
Won Hur ◽  
Hyun Choi ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Electrochemical Determination ◽  
Highly Sensitive ◽  
Poly Acrylic Acid

scholarly journals The Anomalous Influence of Polyelectrolyte Concentration on the Deposition and Nanostructure of Poly(ethyleneimine)/Poly(acrylic acid) Multilayers

Molecules ◽  
2019 ◽  
Vol 24 (11) ◽  
pp. 2141 ◽  
Author(s):  
Martin Müller
Keyword(s):  
Acrylic Acid ◽  
Attenuated Total Reflection ◽  
Silicon Substrates ◽  
Acid Base ◽  
Exponential Relationship ◽  
Individual Adsorption ◽  
The Individual ◽  
Poly Acrylic Acid

The deposition and nanostructure of polyelectrolyte (PEL) multilayers (PEMs) of branched poly(ethyleneimine)/poly(acrylic acid) (PEI/PAA) onto silicon substrates was studied in terms of the dependence of pH and the PEL concentration (cPEL) in the individual adsorption steps z. Both a commercial automatic dipping device and a homebuilt automatic stream coating device (flow cell) were used. Gravimetry, SFM, transmission (TRANS) and in situ attenuated total reflection (ATR) FTIR spectroscopy were used for the quantitative determination of the adsorbed amount, thickness, chemical composition and morphology of deposited PEMs, respectively. Firstly, the combination of pH = 10 for PEI and pH = 4 for PAA, where both PEL were predominantly in the neutral state, resulted in an extraordinarily high PEM deposition, while pH combinations, where one PEL component was charged, resulted in a significantly lower PEM deposition. This was attributed to both PEL conformation effects and acid/base interactions between basic PEI and acidic PAA. Secondly, for that pH combination an exponential relationship between PEM thickness and adsorption step z was found. Thirdly, based on the results of three independent methods, the course of the deposited amount of a PEM-10 (z = 10) versus cPEL in the range 0.001 to 0.015 M at pH = 10/4 was non-monotonous showing a pronounced maximum at cPEL = 0.005 M. Analogously, for cPEL = 0.005 M a maximum of roughness and structure size was found. Fourthly, related to that finding, in situ ATR-FTIR measurements gave evidence for the release of outermost located PEI upon PAA immersion (even step) and of outermost PAA upon PEI immersion (odd step) under formation of PEL complexes in solution. These studies help us to prepare PEL-based films with a defined thickness and morphology for interaction with biofluids in the biomedical and food fields.

Sign in / Sign up

Export Citation Format

Share Document