scholarly journals Probing the Molecular Interactions of Chitosan Films in Acidic Solutions with Different Salt Ions

Coatings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1052
Author(s):  
Qiyan Tan ◽  
Yajing Kan ◽  
Huixiang Huang ◽  
Weiping Wu ◽  
Xinjian Lu
Keyword(s):  
Molecular Interactions ◽  
Contact Time ◽  
Surface Forces Apparatus ◽  
Acidic Solutions ◽  
Interaction Mechanisms ◽  
Salt Ions ◽  
Bridge Model ◽  
Wide Range ◽  
Acidic Conditions ◽  
Chitosan Films

Understanding the interaction mechanisms of chitosan films plays a central role in a wide range of its applications, such as bioadhesive, drug delivery, wound healing, tissue engineering, and wastewater treatment for heavy metal ions. Here, we investigated the molecular interactions between chitosan films in acidic solutions with different salt ions using a surface forces apparatus (SFA). The results showed that chitosan can be adsorbed to mica surfaces by electrostatic interaction under acidic conditions. The force measurements demonstrated that the interactions depend on the salt types, concentrations, and contact time. With the addition of 1 mM LaCl3 and NaCl into the acetic acid (HAc) buffer solution, the cohesion between chitosan films enhanced by about 45% and 20%, respectively, after a contact time of 60 min. The enhanced cohesion induced by the combination of partly intermolecular complexation formation in a bridge model and conformation adjustment of chitosan under contact time in 1 mM LaCl3 solution. However, the cohesion reduced rapidly and even disappeared when the salt concentration increased to 10 mM and 100 mM. We proposed that the cross-linked structures of chitosan mainly contribute to the significant reduction of chitosan cohesion in LaCl3 solution. In comparison, the decrease in cohesion capacity in NaCl solution mainly results from the enhanced hydration effect. Our findings may provide insights into the interaction mechanisms of chitosan films under nanoconfinement in acidic conditions and suggestions for the development of chitosan-based materials.

scholarly journals Drops bouncing off macro-textured superhydrophobic surfaces

2017 ◽  
Vol 824 ◽  
pp. 866-885 ◽  
Author(s):  
Ali Mazloomi Moqaddam ◽  
Shyam S. Chikatamarla ◽  
Iliya V. Karlin
Keyword(s):  
Contact Time ◽  
Numerical Study ◽  
Three Dimensional ◽  
Superhydrophobic Surfaces ◽  
Nonlinear Behaviour ◽  
Textured Surfaces ◽  
Texture Density ◽  
Wide Range ◽  
Quantitative Manner ◽  
The Impact

Recent experiments with droplets impacting macro-textured superhydrophobic surfaces revealed new regimes of bouncing with a remarkable reduction of the contact time. Here we present a comprehensive numerical study that reveals the physics behind these new bouncing regimes and quantifies the roles played by various external and internal forces. For the first time, accurate three-dimensional simulations involving realistic macro-textured surfaces are performed. After demonstrating that simulations reproduce experiments in a quantitative manner, the study is focused on analysing the flow situations beyond current experiments. We show that the experimentally observed reduction of contact time extends to higher Weber numbers, and analyse the role played by the texture density. Moreover, we report a nonlinear behaviour of the contact time with the increase of the Weber number for imperfectly coated textures, and study the impact on tilted surfaces in a wide range of Weber numbers. Finally, we present novel energy analysis techniques that elaborate and quantify the interplay between the kinetic and surface energy, and the role played by the dissipation for various Weber numbers.

STUDY OF HETEROMOLECULAR INTERACTION OF NONAQUEOUS BINARY SOLUTIONS

2020 ◽  
Vol 22 (2) ◽  
pp. 111-114
Author(s):  
D.T. Bozorova ◽  
Sh.P. Gofurov ◽  
A.M. Kokhkharov ◽  
O.B. Ismailova
Keyword(s):  
Binary Mixtures ◽  
Mole Fraction ◽  
Molecular Interactions ◽  
Weak Interactions ◽  
Structural Characteristics ◽  
Refractive Indices ◽  
Binary Solutions ◽  
Wide Range

In this work, the refractometry method was used to study of the molecular interactions and structural characteristics of dimethylformamide-ethanol and cyclohexane-ethanol binary mixtures. The refractive indices of mixtures were measured over a wide range of dimethylformamide and cyclohexane concentrations (0−1.0 mole fractions) at 25°С. It has been shown that heteromolecular complexes in binary solutions are formed at the concentration of ∼0.5 mole fraction of those compounds due to strong H-bonds. Relatively weak interactions are determined at a concentration of ∼0.2 and ∼0.9 mole fraction of dimethylformamide and ∼0.2 and ∼0.8 mole fraction of cyclohexane.

scholarly journals Antibacterial effect of the adhering human Lactobacillus acidophilus strain LB.

1997 ◽  
Vol 41 (5) ◽  
pp. 1046-1052 ◽  
Author(s):  
M H Coconnier ◽  
V Liévin ◽  
M F Bernet-Camard ◽  
S Hudault ◽  
A L Servin
Keyword(s):  
Lactobacillus Acidophilus ◽  
Culture Supernatant ◽  
Oral Treatment ◽  
Shigella Flexneri ◽  
Lactic Acid Production ◽  
Heat Stable ◽  
Wide Range ◽  
Production Activity ◽  
Acidic Conditions

The spent culture supernatant of the human Lactobacillus acidophilus strain LB produces an antibacterial activity against a wide range of gram-negative and gram-positive pathogens. It decreased the in vitro viability of Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Shigella flexneri, Escherichia coli, Klebsiella pneumoniae, Bacillus cereus, Pseudomonas aeruginosa, and Enterobacter spp. In contrast, it did not inhibit lactobacilli and bifidobacteria. The activity was heat stable and relatively sensitive to enzymatic treatments and developed under acidic conditions. The antimicrobial activity was independent of lactic acid production. Activity against S. typhimurium SL1344 infecting human cultured intestinal Caco-2 cells was observed as it was in the conventional C3H/He/oujco mouse model with S. typhimurium C5 infection and oral treatment with the LB spent culture supernatant.

scholarly journals Optimization of the Production of Ethylene Di-Amine Tetra-Acetic Acid Modified Activated Carbon using Palm Kernel Shell for the Adsorption of Copper ion

2021 ◽  
pp. 1-11
Author(s):  
Y. Yerima ◽  
I. Eiroboyi ◽  
I. Eiroboyi
Keyword(s):  
Acetic Acid ◽  
Activated Carbon ◽  
Contact Time ◽  
Copper Ions ◽  
Palm Kernel ◽  
Quadratic Model ◽  
Modified Activated Carbon ◽  
Palm Kernel Shell ◽  
Wide Range ◽  
Adsorbent Dose

Biomass-based activated carbon has received large attention due to its excellent characteristics such as inexpensiveness, good absorption behaviour, and potential to reduce strong dependence towards non-renewable precursors. The potential use of Palm Kernel Shell in modified activated carbon was evaluated by using the Response Surface Methodology. In this study, a 23 three-level Central Composite Design (CCD) was used to develop a statistical model for the optimization of process variables, contact time (10-130mins) X1, pH (5.0 – 8.0) X2, and adsorbent dose (0.4 -5.0g) X3. The investigation shows that Ethylene Di-Amine Tetra-Acetic Acid modified activated carbon prepared from Palm Kernel Shell is a promising adsorbent for the removal of copper ions from aqueous solutions over a wide range of concentrations with an optimized efficiency of 99% at the solution pH of 7.2, contact time of 70 minutes and adsorbent dose of 2.1g/L. The adsorption results are in line with the linear and quadratic model representation, which is evident from the models for optimization of copper ions.

Understanding the molecular interactions of lipopolysaccharides during E. coli initial adhesion with a surface forces apparatus

Soft Matter ◽  
2011 ◽  
Vol 7 (19) ◽  
pp. 9366 ◽  
Author(s):  
Qingye Lu ◽  
Jing Wang ◽  
Ali Faghihnejad ◽  
Hongbo Zeng ◽  
Yang Liu
Keyword(s):  
Molecular Interactions ◽  
Surface Forces ◽  
Surface Forces Apparatus ◽  
E Coli ◽  
Initial Adhesion

Dynamics and Stability of Partial Immersion Milling Operations

1999 ◽  
Author(s):  
M. X. Zhao ◽  
B. Balachandran ◽  
M. A. Davies ◽  
J. R. Pratt
Keyword(s):  
Hopf Bifurcation ◽  
Time Variation ◽  
Periodic Motion ◽  
Contact Time ◽  
Period Doubling ◽  
Experimental Investigations ◽  
Partial Immersion ◽  
Milling Operations ◽  
Wide Range ◽  
The Stability

Abstract In this paper, numerical and experimental investigations conducted into the dynamics and stability of partial immersion milling operations are presented. A mechanics based model is used for simulations of a wide range of milling operations and instabilities that arise due to regeneration and/or impact effects are studied. Poincaré sections are used to assess the stability of motions. The studies reveal that apart from Hopf bifurcation of a periodic motion, a period-doubling bifurcation of a periodic motion may also lead to chatter in partial immersion milling operations. Issues such as tooth contact time variation and structure of stability charts are also discussed.

scholarly journals Large Differences in Urinary Benzene Metabolite S-Phenylmercapturic Acid Quantitation: A Comparison of Five LC–MS-MS Methods

2020 ◽  
Author(s):  
Denise S Tevis ◽  
Andrew Willmore ◽  
Deepak Bhandari ◽  
Brett Bowman ◽  
Chloe Biren ◽  
...  
Keyword(s):  
Human Urine ◽  
Analytical Methods ◽  
Urine Samples ◽  
Genotoxic Carcinogen ◽  
Human Urine Samples ◽  
Ph Values ◽  
Wide Range ◽  
Acidic Conditions ◽  
Hematological Abnormalities ◽  
Reference Samples

Abstract Benzene is a known genotoxic carcinogen linked to many hematological abnormalities. S-phenylmercapturic acid (PHMA, N-acetyl-S-(phenyl)-L-cysteine, CAS# 4775-80-8) is a urinary metabolite of benzene and is used as a biomarker to assess benzene exposure. Pre-S-phenylmercapturic acid (pre-PHMA) is a PHMA precursor that dehydrates to PHMA at acidic pH. Published analytical methods that measure urinary PHMA adjust urine samples to a wide range of pH values using several types of acid, potentially leading to highly variable results depending on the concentration of pre-PHMA in a sample. Information is lacking on the variation in sample preparation among laboratories regularly measuring PHMA and the effect of those differences on PHMA quantitation in human urine samples. To investigate the differences in PHMA quantitation, we conducted an inter-laboratory comparison that included the analysis of 50 anonymous human urine samples (25 self-identified smokers and 25 self-identified non-smokers), quality control samples and commercially available reference samples in five laboratories using different analytical methods. Observed urinary PHMA concentrations were proportionally higher at lower pH, and results for anonymous urine samples varied widely among the methods. The method with the neutral preparation pH yielded results about 60% lower than the method using the most acidic conditions. Samples spiked with PHMA showed little variation, suggesting that the variability in results in human urine samples across methods is driven by the acid-mediated conversion of pre-PHMA to PHMA.

scholarly journals Biodegradation Potential and Diversity of Diclofenac-degrading Microbiota in an Immobilized Cell Biofilter

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 554 ◽  
Author(s):  
Efstathia Navrozidou ◽  
Nikolaos Remmas ◽  
Paraschos Melidis ◽  
Dimitrios G. Karpouzas ◽  
George Tsiamis ◽  
...  
Keyword(s):  
Activated Sludge ◽  
High Throughput Sequencing ◽  
Rhodopseudomonas Palustris ◽  
Carbon Sources ◽  
High Strength ◽  
Adaptation Period ◽  
Immobilized Cell ◽  
Wide Range ◽  
Acidic Conditions ◽  
Ph Decrease

Despite that diclofenac has been embodied to the European watch list of priority substances of concern, studies on diclofenac biodegradation are limited and the diversity of diclofenac-degrading microbiota remains unknown. In this work, an immobilized cell biofilter was constructed and operated to evaluate its effectiveness to depurate high strength diclofenac wastewater and to identify the diclofenac-degrading community accommodated in activated sludge by employing high-throughput sequencing techniques. After a two-month adaptation period, biofilter removal efficiencies reached values as high as 97.63 ± 0.62%, whereas utilization of diclofenac in the immobilized cell biofilter led to a drastic pH decrease. Based on Illumina sequencing, the major bacterial taxa identified in the immobilized cell biofilter were members of the species Granulicella pectinivorans and Rhodanobacter terrae, followed by members of the species Castellaniella denitrificans, Parvibaculum lavamentivorans, Bordetella petrii, Bryocella elongata and Rhodopseudomonas palustris. The ability of such taxa to utilize a wide range of carbon sources and to effectively adapt under acidic conditions seemed to be the main parameters, which favored their prevalence in the immobilized cell biofilter. In addition, Wickerhamiella was the predominant fungal taxon in the immobilized cell biofilter, which appears to be actively involved in diclofenac degradation in activated sludge systems.

Chitosan based antimicrobial films for food packaging applications

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Shipra Tripathi ◽  
G. K. Mehrotra ◽  
P. K. Dutta
Keyword(s):  
Antimicrobial Activity ◽  
Food Packaging ◽  
Antimicrobial Properties ◽  
Food Preservation ◽  
Pathogenic Microorganisms ◽  
Packaging System ◽  
Antimicrobial Packaging ◽  
Wide Range ◽  
Chitosan Films ◽  
Antimicrobial Films

AbstractAntimicrobial packaging is one of the most promising active packaging systems. Antimicrobial packaging is the packaging system that is able to kill or inhibit spoilage and pathogenic microorganisms that are contaminating foods. A tremendous effort has been made over the last decade to develop and test films with antimicrobial properties to improve food safety and shelf life. For food preservation, chitosan films are very effective. Chitosan has widely been used in antimicrobial films, to provide edible protective coating, dipping and spraying for the food products due to its antimicrobial properties. Chitosan can be formed into fibers, films, gels, sponges, beads or nanoparticles. Chitosan films have been used as a packaging material for the quality preservation of a variety of food. Chitosan has great potential for a wide range of applications due to its biodegradability, biocompatibility, antimicrobial activity, non-toxicity and versatile chemical and physical properties. The present review outlines the preparation and antimicrobial activity of chitosan based films.

Adsorption of Acid Red by Porous Chitosan Film

2013 ◽  
Vol 690-693 ◽  
pp. 1184-1187 ◽  
Author(s):  
Tao Feng ◽  
Lei Xu ◽  
Fan Zhang
Keyword(s):  
Contact Time ◽  
Adsorption Equilibrium ◽  
Chitosan Film ◽  
Langmuir Equation ◽  
Equilibrium Isotherms ◽  
Environmental Application ◽  
Batch System ◽  
Porous Chitosan ◽  
Chitosan Films ◽  
Scanning Electron

The preparation, characterization, and environmental application of crosslinked porous chitosan films for Acid red (AR) adsorption have been investigated. The adsorbent was characterized by scanning electron microscope (SEM). The adsorption experiments were carried out in a batch system to optimize operation variables: contact time, Acid red concentration, temperature, and pH. The results indicated crosslinked porous chitosan films could successfully remove 96% of Acid red. The adsorption equilibrium isotherms showed that the sorption processes were better fitted by Langmuir equation.

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