Subjects -> CHEMISTRY (Total: 928 journals)
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CHEMISTRY (661 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
Accounts of Materials Research     Hybrid Journal   (Followers: 1)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 30)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 9)
ACS Catalysis     Hybrid Journal   (Followers: 51)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 23)
ACS Combinatorial Science     Hybrid Journal   (Followers: 21)
ACS Environmental Au     Open Access   (Followers: 11)
ACS Macro Letters     Hybrid Journal   (Followers: 25)
ACS Materials Letters     Open Access   (Followers: 3)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 41)
ACS Nano     Hybrid Journal   (Followers: 187)
ACS Photonics     Hybrid Journal   (Followers: 14)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 31)
Acta Chemica Malaysia     Open Access  
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 8)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 7)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 10)
Adsorption Science & Technology     Open Access   (Followers: 7)
Advanced Electronic Materials     Hybrid Journal   (Followers: 7)
Advanced Functional Materials     Hybrid Journal   (Followers: 72)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 3)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 1)
Advanced Science Focus     Free   (Followers: 6)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 2)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 111)
Advances in Chemical Science     Open Access   (Followers: 51)
Advances in Chemistry     Open Access   (Followers: 34)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 15)
Advances in Environmental Chemistry     Open Access   (Followers: 11)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 33)
Advances in Nanoparticles     Open Access   (Followers: 17)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Polymer Science     Hybrid Journal   (Followers: 51)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Sample Preparation     Open Access   (Followers: 9)
Advances in Science and Technology     Full-text available via subscription   (Followers: 16)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Chemical Education     Open Access   (Followers: 5)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 6)
Aggregate     Open Access   (Followers: 1)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 4)
Alchemy : Jurnal Penelitian Kimia     Open Access  
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 44)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 20)
American Journal of Chemistry     Open Access   (Followers: 37)
American Journal of Plant Physiology     Open Access   (Followers: 9)
Analyst     Hybrid Journal   (Followers: 35)
Analytical Science Advances     Open Access   (Followers: 1)
Angewandte Chemie     Hybrid Journal   (Followers: 144)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 236)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 6)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 4)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 5)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 13)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 1)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Spectroscopy     Full-text available via subscription   (Followers: 23)
Applied Surface Science     Hybrid Journal   (Followers: 31)
Arabian Journal of Chemistry     Open Access   (Followers: 4)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Applied Chemistry Research     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 2)
Asian Journal of Chemical Sciences     Open Access  
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access  
Asian Journal of Physical and Chemical Sciences     Open Access   (Followers: 2)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 7)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Hybrid Journal   (Followers: 203)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 5)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 2)
Biomacromolecules     Hybrid Journal   (Followers: 23)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 3)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 84)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 61)
Bioorganic Chemistry     Hybrid Journal   (Followers: 7)
Biopolymers     Hybrid Journal   (Followers: 15)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 3)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 5)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 1)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 11)
Canadian Mineralogist     Full-text available via subscription   (Followers: 5)
Carbohydrate Polymer Technologies and Applications     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 9)
Carbohydrate Research     Hybrid Journal   (Followers: 23)
Carbon     Hybrid Journal   (Followers: 65)
Carbon Capture Science & Technology     Open Access  
Carbon Trends     Open Access   (Followers: 5)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 9)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 11)
Cell Reports Physical Science     Open Access  
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
Chem     Hybrid Journal   (Followers: 1)
Chem Catalysis     Hybrid Journal  
ChemBioEng Reviews     Full-text available via subscription   (Followers: 3)
ChemCatChem     Hybrid Journal   (Followers: 7)
Chemical and Engineering News     Free   (Followers: 22)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Hybrid Journal   (Followers: 79)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 26)
Chemical Physics Impact     Full-text available via subscription  
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 178)
Chemical Science     Open Access   (Followers: 41)
Chemical Science International Journal     Open Access  
Chemical Technology     Open Access   (Followers: 75)
Chemical Thermodynamics and Thermal Analysis     Open Access   (Followers: 2)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 40)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 17)
ChemInform     Hybrid Journal   (Followers: 5)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Industry     Full-text available via subscription   (Followers: 6)
Chemistry - A European Journal     Hybrid Journal   (Followers: 119)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 19)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 18)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 6)
Chemistry Education Review     Open Access   (Followers: 1)
Chemistry in Education     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 42)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 166)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Hybrid Journal   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal  
Chemistry–Methods     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
ChemNanoMat     Hybrid Journal   (Followers: 1)
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 13)
Chemosensors     Open Access   (Followers: 1)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPhysMater     Full-text available via subscription  
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access  
ChemSystemsChem     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal   (Followers: 1)
CHIMIA International Journal for Chemistry     Open Access   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 9)
Chromatographia     Hybrid Journal   (Followers: 21)
Chromatography     Open Access   (Followers: 2)
Chromatography Research International     Open Access   (Followers: 4)
Ciencia     Open Access  
Clay Minerals     Hybrid Journal   (Followers: 8)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 6)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 2)
Combustion Science and Technology     Hybrid Journal   (Followers: 26)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 1)
Communications Chemistry     Open Access   (Followers: 2)
Communications Materials     Open Access  
Composite Interfaces     Hybrid Journal   (Followers: 6)
Comptes Rendus : Chimie     Open Access  
Comptes Rendus : Physique     Open Access   (Followers: 3)

        1 2 3 4 | Last

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Journal Cover
Colloids and Interfaces
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2504-5377
Published by MDPI Homepage  [84 journals]
  • Colloids and Interfaces, Vol. 6, Pages 38: Phospholipids and Hyaluronan:
           From Molecular Interactions to Nano- and Macroscale Friction

    • Authors: Sixuan Li, Lubica Macakova, Piotr Bełdowski, Per M. Claesson, Andra Dėdinaitė
      First page: 38
      Abstract: Phospholipids and hyaluronan are two key biomolecules that contribute to the excellent lubrication of articular joints. Phospholipids alone and in combination with hyaluronan have also displayed low friction forces on smooth surfaces in micro- and nanosized tribological contacts. In an effort to develop aqueous-based lubrication systems, it is highly relevant to explore if these types of molecules also are able to provide efficient lubrication of macroscopic tribological contacts involving surfaces with roughness larger than the thickness of the lubricating layer. To this end, we investigated the lubrication performance of hyaluronan, the phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and mixtures of these two components using glass surfaces in a mini-traction machine. We compared our data with those obtained using flat silica surfaces in previous atomic force microscopy studies, and we also highlighted insights on hyaluronan–phospholipid interactions gained from recent simulations. Our data demonstrate that hyaluronan alone does not provide any lubricating benefit, but DPPC alone and in mixtures with hyaluronan reduces the friction force by an order of magnitude.
      Citation: Colloids and Interfaces
      PubDate: 2022-06-23
      DOI: 10.3390/colloids6030038
      Issue No: Vol. 6, No. 3 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 17: Effect of Glycerol, Calcium and
           Transglutaminase Post-Treatment on the Properties of Regenerated Fibers
           from Rennet-Treated Casein Micelles

    • Authors: Sebastian Thill, Ronald Gebhardt
      First page: 17
      Abstract: Regenerated fibers can be prepared from a cooled solution of renneted casein micelles in a wet spinning process. For better handling and stability of the fiber, plasticizers, network modifiers or cross-linkers are used in the production process. For that reason, fibers with different glycerol and calcium content are prepared in this study and subsequently treated with the enzyme transglutaminase before being characterized after air drying. In addition to the swelling behavior in NaOH, H2O, simulated milk ultrafiltrate buffer as well as HCl, the mechanical properties of the fibers are investigated, taking into account their microscopic fine structure. Transglutaminase-treated fibers show sigmoidal absorption curves for all solvents and reach higher equilibrium swelling percentages than untreated fibers. When the calcium content in the coagulation bath is increased from 50 mM to 100 mM, more stabilizing calcium bridges lead to a denser fiber structure that swells more slowly in all solvents considered. With increasing glycerol content, the flexibility of the fibers increases, as indicated by the decrease in elastic moduli, and a fine structure in the sub-µm range becomes visible. The fibers also demonstrate lower elastic moduli when post-treated with transglutaminase. Besides the higher casein content due to the transglutaminase treatment, this could also contribute to the higher equilibrium swelling percentages compared to the untreated fibers.
      Citation: Colloids and Interfaces
      PubDate: 2022-03-22
      DOI: 10.3390/colloids6020017
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 18: Citric-Acid-Assisted
           Preparation of Biochar Loaded with Copper/Nickel Bimetallic Nanoparticles
           for Dye Degradation

    • Authors: Jessim Omiri, Youssef Snoussi, Arvind K. Bhakta, Stéphanie Truong, Souad Ammar, Ahmed M. Khalil, Mohamed Jouini, Mohamed M. Chehimi
      First page: 18
      Abstract: Immobilization of nanocatalysts on biochar is receiving unprecedented interest among material and catalysis scientists due to its simplicity, versatility, and high efficiency. Herein, we propose a new direct approach to obtain bimetallic copper/nickel nanoparticles loaded on olive stone biochar. The bimetallic-coated biochar and the reference materials, namely bare biochar, copper rich-loaded biochar, and nickel-loaded biochar, were prepared by pyrolysis from olive pit powder particles impregnated first with citric acid (CA) and then with copper and nickel nitrates at 400 °C under nitrogen flow. We employed citric acid in the process in order to examine its effect on the structural and textural properties of biochar supporting the metallic nanoparticles. Surprisingly, citric acid induced the formation of agglomerated or even raspberry-shaped bimetallic copper/nickel nanoparticles. Large 450–500 nm agglomerates of ~80 nm bimetallic CuNi NPs were noted for B-CA@CuNi. Interestingly, for biochar material prepared with initial Cu/Ni = 10 molar ratio (B-CA@CuNi10/1), the bimetallic NPs formed unusual nanoraspberries (174 ± 8 nm in size), which were agglomerates of individual 10–20 nm CuNi10/1 nanoparticles. The B-CA@CuNi and reference materials were characterized by Raman spectroscopy, scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and magnetometry. The B-CA@CuNi and B-CA@Ni materials could be efficiently attracted with a magnet but not B-CA@CuNi10/1 due to the low nickel loading. B-CA@CuNi was tested as a catalyst for the degradation of methyl orange (MO). Discoloration was noted within 10 min, much faster than a similar material prepared in the absence of CA. B-CA@CuNi could be recycled at least 3 times while still exhibiting the same fast catalytic discoloration performance. This paper stresses the important role of citric acid in shaping bimetallic nanoparticles loaded in situ on biochar during the slow pyrolysis process and in enabling faster catalytic discoloration of organic dye solution.
      Citation: Colloids and Interfaces
      PubDate: 2022-03-22
      DOI: 10.3390/colloids6020018
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 19: Proposed Methods for Testing
           and Comparing the Emulsifying Properties of Proteins from Animal, Plant,
           and Alternative Sources

    • Authors: David Julian McClements, Jiakai Lu, Lutz Grossmann
      First page: 19
      Abstract: The food industry is trying to reformulate many of its products to replace functional ingredients that are chemically synthesized or isolated from animal sources (such as meat, fish, eggs, or milk) with ingredients derived from plant or microbial sources. This effort is largely a result of the demand for foods that are better for the environment, human health, and animal welfare. Many new kinds of plant- or microbial-derived proteins are being isolated for potential utilization as functional ingredients by the food industry. A major challenge in this area is the lack of standardized methods to measure and compare the functional performance of proteins under conditions they might be used in food applications. This information is required to select the most appropriate protein for each application. In this article, we discuss the physicochemical principles of emulsifier functionality and then present a series of analytical tests that can be used to quantify the ability of proteins to form and stabilize emulsions. These tests include methods for characterizing the effectiveness of the proteins to promote the formation and stability of the small droplets generated during homogenization, as well as their ability to stabilize the droplets against aggregation under different conditions (e.g., pH, ionic composition, temperature, and shearing). This information should be useful to the food industry when it is trying to identify alternative proteins to replace existing emulsifiers in specific food applications.
      Citation: Colloids and Interfaces
      PubDate: 2022-03-24
      DOI: 10.3390/colloids6020019
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 20: Triazine 2D Nanosheets as a New
           Class of Nanomaterials: Crystallinity, Properties and Applications

    • Authors: Valery N. Zakharov, Igor K. Kudryavtsev, Sergey F. Dunaev, Kseniya A. Paseshnichenko, Leonid A. Aslanov
      First page: 20
      Abstract: Based on the recent (2015–2021) literature data, the authors analyze the mutual dependence of crystallinity/amorphism and specific surface area and porosity in covalent triazine frameworks (CTFs), taking into account thermodynamic and kinetic control in the synthesis of these 2D nanosheets. CTFs have now become a promising new class of high-performance porous organic materials. They can be recycled and reused easily, and thus have great potential as sustainable materials. For 2D CTFs, numerous examples are given to support the known rule that the structure and properties of any material with a given composition depend on the conditions of its synthesis. The review may be useful for elder students, postgraduate students, engineers and research fellows dealing with chemical synthesis and modern nanotechnologies based on 2D covalent triazine frameworks.
      Citation: Colloids and Interfaces
      PubDate: 2022-03-30
      DOI: 10.3390/colloids6020020
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 21: Thermal Analysis Tools for
           Physico-Chemical Characterization and Optimization of Perfluorocarbon
           Based Emulsions and Bubbles Formulated for Ultrasound Imaging

    • Authors: Yohann Corvis, Frédéric Rosa, Minh-Tien Tran, Gilles Renault, Nathalie Mignet, Sylvie Crauste-Manciet, Philippe Espeau
      First page: 21
      Abstract: Self-emulsifying microbubbles, especially designed to increase the contrast of ultrasound images by the inclusion of perfluorocarbon molecules, have been studied by thermal analysis techniques. The microbubbles were made of a blend of gas (20%), surfactants (50%) and water (30%). The surfactants were mixtures of polysorbate-85, Span-80, poloxamer 188, glycerol and fluorinated surfactant (Zonyl®). Microbubbles have been characterized by means of diffusion light scattering and optical imaging. The effect of Zonyl® on encapsulation rate, as well as gas vaporization temperature and gas release temperature, has been assessed by means of Differential Scanning Calorimetry (DSC) and Thermogravimetric Analyses (TGA). Microscopy and laser granulometry techniques have been also carried out for each formulation in order to determine the number of microbubbles and their size, respectively. Moreover, stability of the emulsions has been evaluated by DSC and confronted with the results obtained from the ultrasound experiments. Average microbubble concentrations of 7.2 × 107 and 8.9 × 107 per mL were obtained for perfluorohexane and perfluoropentane based emulsions, respectively. The present study demonstrates that the amount of encapsulated perfluorocarbon increases and the gas evaporation temperature decreases with the concentration of Zonyl®. Furthermore, the best ultrasound contrast images have been obtained in vitro with the samples containing the lowest Zonyl® concentration. An explication regarding the role of Zonyl® in the emulsion/microbubbles preparations is proposed here in order to optimize self-emulsifying microbubble formulation for pharmaceutical development.
      Citation: Colloids and Interfaces
      PubDate: 2022-04-01
      DOI: 10.3390/colloids6020021
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 22: Efficient Adsorption Removal of
           an Anionic Azo Dye by Lignocellulosic Waste Material and Sludge Recycling
           into Combustible Briquettes

    • Authors: Abderrahim Kali, Abdelouahed Amar, Ilyasse Loulidi, Chaimaa Hadey, Maria Jabri, Awad A. Alrashdi, Hassane Lgaz, Mohamed Sadoq, Abderrazek El-kordy, Fatima Boukhlifi
      First page: 22
      Abstract: In recent years, the removal of dyes has emerged as a significant problem that attracted several researchers. The search for green and eco-friendly adsorbents has been a never-ending task in environmental protection to overcome this issue. Herein, almond shells (AS) were used as an adsorbent to remove methyl orange (MO) from aqueous solutions. The AS was characterized using several techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). Adsorption experiments were carried out under different pH, temperature, and AS particle size conditions. Kinetic and isothermal studies revealed that MO adsorption on the AS reached equilibrium at 90 min, following the pseudo-second-order (PSO) kinetic model. The Langmuir adsorption isotherm was found the suitable adsorption model for MO adsorption on AS, showing a maximum adsorption capacity of 15.63 mg/g. Thermodynamic parameters such as the change in standard enthalpy (ΔH°), the change in standard entropy (ΔS°), and the change in standard free energy (ΔG°) indicated that the MO dye adsorption process is non-spontaneous, endothermic, and physical, which was further confirmed from FTIR analysis of AS samples after adsorption. The contaminated sludge was converted into biochar by slow pyrolysis at a temperature of 400 °C for 2 h. Biochar has been exploited for the manufacture of combustible briquettes.
      Citation: Colloids and Interfaces
      PubDate: 2022-04-06
      DOI: 10.3390/colloids6020022
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 23: Relevance of Colloid Inherent
           Salt Estimated by Surface Complexation Modeling of Surface Charge
           Densities for Different Silica Colloids

    • Authors: Alok Goel, Johannes Lützenkirchen
      First page: 23
      Abstract: Potentiometric titrations have been routinely used to measure the proton-related surface charge density (SCD) of particles in solution. Here, we quantify the SCD of silica nanoparticles (NPs) that are commercially available as charge-stabilized colloids (by the addition of NaOH) in the presence of known amounts of added NaCl. The experimental results are simulated by surface complexation models (SCMs) of the electrical double layer (EDL). The modeling results suggest that involving only the added NaCl electrolyte yields poor agreement between the experiment and the best achievable fit. An increase in the Na concentration accounting for the colloid inherent salt (CIS) associated with these charge-stabilized colloids results in much better simulations. In the available literature, this CIS has often been disregarded. However, in the modeling, the total concentration of Na must be known for a consistent mole balance and derivation of reliable ion-pair binding constants. If the CIS is not accounted for or the original suspensions are not dialyzed, the presence of CIS renders the study of those colloids difficult, particularly when investigating specific ion effects, since the CIS always interferes. In the present work, we show that the SCM-estimated amount of CIS from varying the total salt and solid concentration agrees surprisingly well with the manufacturer specification.
      Citation: Colloids and Interfaces
      PubDate: 2022-04-06
      DOI: 10.3390/colloids6020023
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 24: Diffusiophoresis of a Soft
           Particle as a Model for Biological Cells

    • Authors: Hiroyuki Ohshima
      First page: 24
      Abstract: We derive the general expression for the diffusiophoretic mobility of a soft particle (i.e., polyelectrolyte-coated hard particle) in a concentration gradient of electrolytes for the case in which the particle’s core size is large enough compared with the Debye length. Therefore, the particle surface can be regarded as planar, and the electrolyte concentration gradient is parallel to the core surface. The obtained expression can be applied for arbitrary values of the fixed charge density of the polyelectrolyte layer and the surface charge density of the particle core. We derive approximate analytic mobility expressions for soft particles of three types, i.e., (i) weakly charged soft particles, (ii) soft particles with a thick polyelectrolyte layer, in which the equilibrium electric potential deep inside the polyelectrolyte layer is equal to the Donnan potential, and (iii) soft particles with an uncharged polymer layer of finite thickness.
      Citation: Colloids and Interfaces
      PubDate: 2022-04-14
      DOI: 10.3390/colloids6020024
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 25: Charged Colloids at the
           Metal–Electrolyte Interface

    • Authors: Ioulia Chikina, Sawako Nakamae, Valeriy Shikin, Andrey Varlamov
      First page: 25
      Abstract: We discuss the peculiarities of the structure of the interface between a metal and a stable colloidal dispersion of charged nanoparticles in an electrolyte. It is demonstrated that a quasi-2D ionic structure of elevated density arises in its vicinity due to the effect of electrostatic image forces. The stabilized colloidal particles, being electroneutral and spatially distributed objects in the bulk of the electrolyte and approaching the interface, are attracted to it. In their turn, the counterions forming their coat partially retract into the 2D-layer, which results in an acquisition by the colloidal particle of the effective charge eZ*≫e and which, together with its mirror image, creates the electric dipole. The formed dipoles, possessing the moments directed perpendicularly to the interface, form the gas with repulsion between particles. The intensity of this repulsion, evidently, depends on the value of the effective charge eZ* acquired by the nanoparticle having lost a number of counterions. It can be related to the value of the excess osmotic pressure Posm measured in the experiment. On the other hand, this effective charge can be connected by means of the simple geometric consideration with the structural charge eZ of the nanoparticle core being in the bulk of the electrolyte.
      Citation: Colloids and Interfaces
      PubDate: 2022-04-20
      DOI: 10.3390/colloids6020025
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 26: Limnophila aromatica Crude
           Extracts as Natural Emulsifiers for Formation and Stabilizing of
           Oil-in-Water (O/W) Emulsions

    • Authors: Rasmey Soeung, Lorena de Oliveira Felipe, Meryem Bouhoute, Noamane Taarji, Mitsutoshi Nakajima, Marcos A. Neves
      First page: 26
      Abstract: This study mainly focused on the emulsifying performance of Limnophila aromatica crude extracts obtained by using different ethanolic aqueous solutions (0, 25, 50, 75, and 99.5% (v/v)). All Limnophila aromatica extracts (LAEs) were able to produce emulsions with a volume mean droplet diameter (d4,3) ranging from 273 to 747 nm, except for LAE-99.5 (3269 nm). Only the emulsion prepared by LAE-75 was stable during seven days of storage, without significantly changing droplet size (479–495 nm). The result showed that all LAEs could reduce interfacial tension varied within 12.5 and 16.1 mN/m at the soybean oil/extracts (1% w/w) interface. Compared to other extracts, LAE-75 did not contain the highest protein, saponin, and phenol content (4.36%, 20.14%, and 11.68%, respectively), but it had the lowest ash content (14.74%). These results indicated that the emulsifying performance of LAEs did not rely only on interfacial tension and/or surface-active compounds. The residual demulsifiers, such as inorganic substances, were also significantly involved in the emulsions’ destabilization. Finally, the emulsion consisting of 0.5% (w/w) LAE-75 and 5% (w/w) soybean oil showed considerable stability during storage up to 30 days at different temperatures (5 or 25 °C). Therefore, Limnophila aromatica extract has a potential application as a new source of natural emulsifier.
      Citation: Colloids and Interfaces
      PubDate: 2022-04-24
      DOI: 10.3390/colloids6020026
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 27: Effects of Oil Phase on the
           Inversion of Pickering Emulsions Stabilized by Palmitic Acid Decorated
           Silica Nanoparticles

    • Authors: Andrés González-González, Natalia Sánchez-Arribas, Eva Santini, José Luis Rodríguez-Villafuerte, Carlo Carbone, Francesca Ravera, Francisco Ortega, Libero Liggieri, Ramón G. Rubio, Eduardo Guzmán
      First page: 27
      Abstract: Pickering emulsions stabilized by the interaction of palmitic acid (PA) and silica nanoparticles (SiNPs) at the water/oil interface have been studied using different alkane oil phases. The interaction of palmitic acid and SiNPs has a strong synergistic character in relation to the emulsion stabilization, leading to an enhanced emulsion stability in relation to that stabilized only by the fatty acid. This results from the formation of fatty acid-nanoparticle complexes driven by hydrogen bond interactions, which favor particle attachment at the fluid interface, creating a rigid armor that minimizes droplet coalescence. The comparison of emulsions obtained using different alkanes as the oil phase has shown that the hydrophobic mismatch between the length of the alkane chain and the C16 hydrophobic chain of PA determines the nature of the emulsions, with the solubility of the fatty acid in the oil phase being a very important driving force governing the appearance of phase inversion.
      Citation: Colloids and Interfaces
      PubDate: 2022-04-25
      DOI: 10.3390/colloids6020027
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 28: Impact of Polymer Nanoparticles
           on DPPC Monolayer Properties

    • Authors: Alexey Bykov, Olga Milyaeva, Alexander Akentiev, Maria Panaeva, Nikolaj Isakov, Reinhard Miller, Boris Noskov
      First page: 28
      Abstract: The application of surface rheology and Brewster angle microscopy on mixed monolayers of DPPC and polymeric nanoparticles (cationic and anionic) showed that the sign of the particle charge affects the dynamic properties of the monolayers less than the nanoparticles’ ability to aggregate. Under almost physiological conditions, the effect of nanoparticles on the elasticity of DPPC monolayer is insignificant. However, the particles prevent the surface tension from decreasing to extremely low values. This effect could affect the functionality of pulmonary surfactants.
      Citation: Colloids and Interfaces
      PubDate: 2022-04-26
      DOI: 10.3390/colloids6020028
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 29: Synthesis and Application of
           Albumin Nanoparticles Loaded with Prussian Blue Nanozymes

    • Authors: Pavel Khramtsov, Maria Kropaneva, Maria Bochkova, Valeria Timganova, Dmitriy Kiselkov, Svetlana Zamorina, Mikhail Rayev
      First page: 29
      Abstract: Prussian blue nanozymes exhibit peroxidase-like catalytic activity and are therefore considered a stable and inexpensive alternative to natural peroxidases in the enzyme-linked immunosorbent assay (ELISA). In this work, we propose a robust method of Prussian blue nanozyme functionalization, which relies on the entrapment of nanozymes into albumin nanoparticles. The principle of the method is the addition of ethanol to a solution that contains albumin and nanozymes. At a high ethanol concentration solubility of albumin decreases, resulting in the formation of albumin nanoparticles loaded with nanozymes. The hydrodynamic diameter of nanoparticles was between 120 and 230 nm and depended on the nanozyme-to-BSA ratio. Encapsulation efficiency of nanozymes reached 96–99% and up to 190 μg of nanozymes were loaded per 1 mg of nanoparticles. Nanoparticles were stable at pH 5.5–7.5 and upon long-term storage in deionized water. Excellent reproducibility of the synthesis procedure was confirmed by the preparation of three individual batches of Prussian-blue-loaded BSA nanoparticles with almost identical properties. Nanoparticles were functionalized with monoclonal antibodies using glutaraldehyde cross-linking. The resulting conjugates were applied as labels in an ELISA-like assay of tumor marker prostate-specific antigen (PSA). The lower limit of detection was below 1 ng/mL, which enables measurement of PSA in the range of clinically relevant concentrations.
      Citation: Colloids and Interfaces
      PubDate: 2022-05-08
      DOI: 10.3390/colloids6020029
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 30: Optical Switches for Lipid
           Membranes: Computed Molecular Projection Area as a Switch Selection
           Criterion

    • Authors: Ivan Boldyrev
      First page: 30
      Abstract: Optical switches in lipid membranes are an emerging tool to tune the properties of the bilayer or membrane protein integrated therein. Here, we use simple geometry and physics considerations to deduce structural criteria to design efficient photoactivated switches for lipid membranes. We compare how the area of projection on the bilayer of various classes of photoswitches changes upon the trans/cis or open/closed transition and show that azobenzene and stilbene should distort the bilayer structure the most. We also conclude that planar-elongated molecules, in which atoms of isomerizable double bond have no additional substituents, while substituents of the fragments adjacent to the double bond prevent formation of the planar molecule in cis configuration, are to be the best photoswitches for lipid membranes.
      Citation: Colloids and Interfaces
      PubDate: 2022-05-09
      DOI: 10.3390/colloids6020030
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 31: Interfacial Flows and
           Interfacial Shape Modulation Controlled by the Thermal Action of Light
           Energy

    • Authors: Natalia Ivanova
      First page: 31
      Abstract: The review covers the research on thermocapillary convection caused by the thermal action of laser radiation in single-layer and bilayer liquid systems of capillary thickness. The advantages of using optical radiation are the instantaneous delivery of thermal energy to a place on demand (a bulk phase, interfaces); low radiation power required; concentrating heat flux on a spot of a few micrometers; the production of arbitrary spatial distributions of radiation intensity; and, as a result, corresponding thermal fields at a liquid interface and their fast reconfiguration. Thermocapillary stresses at the liquid interfaces lead to the transfer of the liquid and a change in the shape of the interface, in accordance with the distribution of the light-induced thermal field. Studies concerned with the methods of non-destructive testing of liquid media and solids, which are based on a photothermocapillary signal emitted by a laser-induced concave deformation of a thin layer, are considered. Features of thermocapillary deformation of a liquid–air interface caused by local heating of thin and thick (exceeding the capillary length) layers are demonstrated. A part of the review addresses the results of the study of thermocapillary rupture of films in the heating zone and the application of this effect in semiconductor electronics and high-resolution lithography. The works on the light-induced thermocapillary effect in bilayer (multilayer) liquid systems are analyzed, including early works on image recording liquid layer systems, liquid IR transducers, and nonlinear optical media.
      Citation: Colloids and Interfaces
      PubDate: 2022-05-13
      DOI: 10.3390/colloids6020031
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 32: The Effect of the Open
           Vase-like Microcapsules Formation with NiFe Double-Hydroxide Walls during
           Hydrolysis of the Mixture NiSO4 and FeSO4 Salt Solution Microdroplets
           Deposited on the Alkaline Solution Surface

    • Authors: Valeri P. Tolstoy, Alexandra A. Meleshko, Anastasia A. Golubeva, Elizaveta V. Bathischeva
      First page: 32
      Abstract: In this work, the conditions for the synthesis of open vase-like microcapsules with a size of 1–5 μm and 20–40 nm walls of NiFe0.3(OH)x layered double hydroxide were studied. These microcapsules were obtained by the rapid hydrolysis of microdroplets of a solution of a mixture of NiSO4 and FeSO4 salts at the surface of an alkali solution. A hypothetical model of successive chemical processes occurring at the interface during synthesis is presented. The features of the “rim” formation around each microcapsule hole from the wall material with a peculiar nozzle-like shape are noted. These microcapsules can be transferred to the surface of a nickel foil using the Langmuir–Schaefer (LS) method. During the transfer process, they are fixed to the surface in an oriented position with a “rim” that contacts the nickel surface. It was established that electrodes made of such a foil with a layer of microcapsules exhibit active electrocatalytic properties in the oxygen evolution reaction during the electrolysis of water in an alkaline medium.
      Citation: Colloids and Interfaces
      PubDate: 2022-05-23
      DOI: 10.3390/colloids6020032
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 33: Nanofluid Structural Forces
           Alter Solid Wetting, Enhancing Oil Recovery

    • Authors: Pingkeng Wu, Alex D. Nikolov, Darsh T. Wasan
      First page: 33
      Abstract: Nanofluids have attracted significant research interest for their promising application in enhanced oil recovery. One striking feature leading to the outstanding efficiency of nanofluids in enhanced oil recovery is the structure of nanoparticles, which induces oscillatory structural forces in the confined space between fluid–fluid interfaces or air–liquid and liquid–solid interfaces. To promote the understanding of the oscillatory structural forces and their application in enhanced oil recovery, we reviewed the origin and theory of the oscillatory structural forces, factors affecting their magnitude, and the experimental techniques demonstrating their impacts on enhanced oil recovery. We also reviewed the methods, where the benefits of nanofluids in enhanced oil recovery provided by the oscillatory structural forces are directly manifested. The oscillatory structural forces promote the wetting and spreading of nanofluids on solid surfaces, which ultimately enhances the separation of oil from the reservoir. Some imbibition tests demonstrated as much as 50% increased oil recovery, compared to the cases where the oscillatory structural forces were absent.
      Citation: Colloids and Interfaces
      PubDate: 2022-05-25
      DOI: 10.3390/colloids6020033
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 34: Control of Electrolyte
           Filtration through a Charged Porous Layer (Membrane) Using a Combination
           of Pressure Drop and an External Electric Field

    • Authors: Anatoly Filippov, Tamara Philippova
      First page: 34
      Abstract: A novel method is proposed for calculating the solvent flux density and electric current density in the process of flow of an electrolyte solution through a charged porous layer (membrane) under the simultaneous action of external pressure and electric potential gradients. The method is based on irreversible thermodynamics and the cell model of an ion-exchange membrane. It is shown that, with the increase in the electrolyte concentration, the total permeability of the porous structure also increases as a result of both barofiltration and electroosmotic transfer of the solvent when both external gradients are co-directional vectors. As for the current density, it also increases with the increasing electrolyte concentration owing to the growth of the streaming current and specific conductivity.
      Citation: Colloids and Interfaces
      PubDate: 2022-05-25
      DOI: 10.3390/colloids6020034
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 35: Levofloxacin and Amikacin
           Adsorption on Nanodiamonds: Mechanism and Application Prospects

    • Authors: Tianyi Shen, Maria G. Chernysheva, Gennadii A. Badun, Andrey G. Popov, Alexander V. Egorov, Neli M. Anuchina, Ivan S. Chaschin, Natalia P. Bakuleva
      First page: 35
      Abstract: This research is focused on the adsorption modification of detonation nanodiamond surfaces with antibiotics for their further use as smart materials for cardiovascular surgery purposes, namely as bioprostheses modifiers. Tritium-labeled amikacin and levofloxacin were used as tracers for the adsorption process control. We found that nanodiamonds form adsorption complexes with levofloxacin via physical adsorption, while in the case of amikacin, electrostatic attraction contributes to the formation of more stable complexes, even in the presence of electrolytes and desorbing agents (models of biological fluids). Antimicrobial characterization of nanodiamond–levofloxacin and nanodiamond–amikacin complexes indicates a reduction in the dose of antibiotics that is used as an antimicrobial agent. Therefore, the use of biomaterial based on DND complexes with antibiotics as the basis of bioprostheses will allow one either to avoid or significantly reduce the duration and intensity of antibiotics use in the postoperative period, which is critically important from the viewpoint of the development of antibiotic resistance in pathogens.
      Citation: Colloids and Interfaces
      PubDate: 2022-05-29
      DOI: 10.3390/colloids6020035
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 36: Line Patterns and Fractured
           Coatings in Deposited Colloidal Hydrochar on Glass Substrates after
           Evaporation of Water

    • Authors: Xia Wang, Niklas Hedin
      First page: 36
      Abstract: Patterns of assembled colloidal particles can form on substrates due to solvent evaporation, and here we studied such phenomena in the drying of monodispersed colloidal hydrochar dispersions prepared by the hydrothermal carbonization of glucose and purified by dialysis. During the evaporation of water, line patterns or, in some cases, mud-like patterns formed. The line formation was investigated as a function of the pH of the dispersion, substrate shape, particle concentration, and concentration of sodium dodecylsulfate (SDS). The lines comprised dense assemblies of hydrochar particles. The line width increased with the successive evaporation of water. Sharper lines formed with the addition of SDS, which was ascribed to the effects of solubilization or moderated interactions. At greater particle concentrations, we also observed a continuous layer of colloidal particles between the lines. A mechanism for the line pattern formation derived from the literature on other colloids was proposed. Mud-like patterns formed on the substrate in concentrated samples without SDS addition and were put in the context of the formation of cracks in the drying of colloidal coatings. Hydrochars belong to carbon-rich colloids, which are of fundamental and technological importance. This research could be useful for in situ line printing within microfluidic devices, for example.
      Citation: Colloids and Interfaces
      PubDate: 2022-05-30
      DOI: 10.3390/colloids6020036
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 37: A Sebum-Mimetic Lipid Monolayer
           and Its Interaction with (Bio)Surfactants

    • Authors: Ilona Jurek, Kamil Wojciechowski
      First page: 37
      Abstract: Surfactants present in cleansing formulations interact not only with the unwanted lipids accumulating on the human skin (dirt) but also with its protective lipidic layer (sebum). Development of simple models of human sebum would help to compare different surfactants and biosurfactants under the same conditions. In this contribution we propose a first monolayer model of synthetic sebum composed of lard, stearic acid, lanolin, squalane and cholesterol. The monolayer compression isotherm features a gas-liquid (G-LE1), two liquid-liquid transitions (LE1-LE2 and LE2-LC), and a collapse at πcoll = 45 mN/m. The monolayer spread on pure water and pre-compressed to π0 = 30 mN/m was exposed to four synthetic surfactants (sodium lauryl sulfate (SLS), sodium laureth sulfate (SLES), ammonium lauryl sulfate (ALS) and cocamidopropyl betaine (CAPB)) and four plant extracts (oat (Avena sativa L.), horse chestnut (Aesculus hippocastanum L.), cowherb (Vaccaria hispanica [P. Mill.] Rauschert), soybean (Glycine max L.) and soapwort (Saponaria officinalis L.)) introduced to the subphase at a dry mass content of 1% (w/w). Three modes of the monolayer-(bio)surfactant interactions were observed: (1) complete solubilization (SLS, SLES, ALS, CAPB); (2) penetration accompanied by an increase of surface pressure and elasticity but without solubilization (horse chestnut, cowherb, soapwort); (3) no interaction (oat, soybean).
      Citation: Colloids and Interfaces
      PubDate: 2022-06-20
      DOI: 10.3390/colloids6020037
      Issue No: Vol. 6, No. 2 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 3: Microrheology to Understand the
           Viscosity Behavior of a Sophorolipid Biosurfactant

    • Authors: Jochen Kleinen, Jan Langwald, Joachim Venzmer, Hacer Yalcinkaya
      First page: 3
      Abstract: The microstructure of the aqueous solutions of purified acidic Sophorolipid (SL) has previously been studied using highly sophisticated methods such as SANS and Cryo-TEM. We were interested in whether (a) the main findings also apply to commercially available SL (which is a mixture of acidic and lactonic SL) and (b) more readily available methods such as DLS can be used to gain insight into the molecular aggregation of SL. Our work was motivated by the increasing interest in biosurfactants for applications in personal and household care. Moreover, the origin behind the more or less lack of rheological response to changes in pH is of practical relevance, as it is somewhat unusual for a carboxylate-group containing surfactant. By using DLS microrheology, we could elucidate the aggregation structure and dynamics of the surfactant on a microscopic scale. Surprisingly, the different degrees of protonation only impacted the microscopic properties such as exchange kinetics and the plateau values of the storage moduli.
      Citation: Colloids and Interfaces
      PubDate: 2022-01-04
      DOI: 10.3390/colloids6010003
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 4: Catalytic Production of
           Levulinic and Formic Acids from Fructose over Superacid
           ZrO2–SiO2–SnO2 Catalyst

    • Authors: Nataliia Hes, Artur Mylin, Svitlana Prudius
      First page: 4
      Abstract: Catalytic conversion of fructose to levulinic and formic acids over tin-containing superacid (H0 = −14.52) mixed oxide was studied. Mesoporous ZrO2–SiO2–SnO2 (Zr:Si:Sn = 1:2:0.4) was synthesized by the sol–gel method. The fructose transformation was carried out in a rotated autoclave at 160–190 °C for 1–5 h using a 20 wt.% aqueous solution. The results showed that doping ZrO2–SiO2 samples with Sn4+ ions improved both fructose conversion and selectivity toward levulinic and formic acids. Under optimal conditions of 180 °C, 3.5 h and fructose to catalyst weight ratio 20:1, levulinic and formic acids yields were 80% and 90%, respectively, at complete fructose conversion. At this, humic substances formed in the quantity of 10 wt.% based on the target products.
      Citation: Colloids and Interfaces
      PubDate: 2022-01-08
      DOI: 10.3390/colloids6010004
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 5: Dendritic Pattern Formation and
           Contact Line Forces during Dewetting of Dilute Polymer Solutions on a
           Hydrophobic Surface

    • Authors: Volfango Bertola
      First page: 5
      Abstract: The micro-scale morphology of the receding contact line of dilute polyethylene oxide solution drops (c ∼ 100 ppm) after impact and inertial spreading on a fluorinated hydrophobic surface is investigated. One can observe the formation of transient liquid filaments and dendritic structures that evolve into a bead-on-a-string structure similar to the well-known capillary breakup mechanism of dilute polymer solutions, which confirm the interaction between stetched polymer coils and the receding three-phase contact line. The estimation of the average polymer force per unit contact line lenght provides a quantitative explanation for the reduction of the contact line retraction velocity reduction observed experimentally.
      Citation: Colloids and Interfaces
      PubDate: 2022-01-11
      DOI: 10.3390/colloids6010005
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 6: Surface Properties of
           Plasma-Activated Chitosan Foils

    • Authors: Konrad Terpiłowski, Emil Chibowski
      First page: 6
      Abstract: Thin films of chitosan are often deposited on various surfaces to provide them with antiseptic properties. In the presented research, chitosan foils were obtained using two methods and treated with nitrogen plasma. The obtained materials were characterized by measuring the wettability of the test liquids, and the apparent surface free energy was calculated using the Tadmor equilibrium contact angles. The surface topography was characterized using optical profilometry and SEM. On the other hand, the effect of plasma on surface groups was investigated using the FTIR-ATR technique. Plasma activation of the surface increases the polarity of the surface. This is observed in the changed surface roughness and the share of functional groups on the surface.
      Citation: Colloids and Interfaces
      PubDate: 2022-01-17
      DOI: 10.3390/colloids6010006
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 7: A New Design for Magnetic
           Poly(vinyl pivalate) for Biomedical Applications: Synthesis,
           Characterization, and Evaluation of Cytotoxicity in Fibroblasts,
           Keratinocytes, and Human Melanoma Cells

    • Authors: Robson T. Araujo, Maria S. B. Neta, José A. H. Coaquira, Sacha B. Chaves, Fabricio Machado
      First page: 7
      Abstract: Polymers containing magnetic properties play an important role in biomedical therapies, such as embolotherapy or hyperthermia, for their differentiated properties. In this work, magnetite (Fe3O4) nanoparticles were synthesized by the coprecipitation method and dispersed into a thermoplastic matrix of poly(vinyl pivalate) through an emulsion polymerization process. The main goal was the individual encapsulation of magnetite nanoparticles to improve the magnetic response of the magneto-polymeric materials using polymerizable carboxylic acids as coating agents, minimizing the leaching of nanoparticles throughout the nanocomposite formation. For this purpose, synthesized magnetite had its surface modified by acrylic acid or methacrylic acid to improve its individual encapsulation during the polymerization step, thus generating a series of magnetic nanocomposite materials containing different amounts of magnetite intended for biomedical applications. X-ray diffractometry and TEM measurements provided a mean size of approximately 8 nm for the pure magnetite nanoparticles and a spherical morphology. Acid-functionalized Fe3O4 had a size of approximately 6 nm, while the nanocomposites showed a size of approximately 7 nm. Magnetization measurement provided a saturation magnetization value of approximately 75 emu/g and confirmed superparamagnetic behavior at room temperature. DSC analysis showed a glass transition temperature of 65 °C for poly(vinyl pivalate)-based nanocomposites. The tests realized with homopolymer and magnetic composites against different cell lineages (i.e., fibroblasts, keratinocytes, and human melanoma) to evaluate the levels of cytotoxicity showed good results in the different exposure times and concentrations used, since the obtained results showed cell viability greater than 70% compared to the control group, suggesting that the synthesized materials are very promising for medical applications.
      Citation: Colloids and Interfaces
      PubDate: 2022-01-21
      DOI: 10.3390/colloids6010007
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 8: Acknowledgment to Reviewers of
           Colloids and Interfaces in 2021

    • Authors: Colloids; Interfaces Editorial Office
      First page: 8
      Abstract: Rigorous peer-reviews are the basis of high-quality academic publishing [...]
      Citation: Colloids and Interfaces
      PubDate: 2022-01-25
      DOI: 10.3390/colloids6010008
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 9: Optimization and Antibacterial
           Response of N-Halamine Coatings Based on Polydopamine

    • Authors: Nadia Nazi, Adeline Marguier, Catherine Debiemme-Chouvy, Vincent Humblot
      First page: 9
      Abstract: Due to the ability of microorganisms to first adhere to a material surface and then to lead to the formation of a biofilm, it is essential to develop surfaces that have antimicrobial properties. It is well known that N-halamine coatings allow us to prevent or minimize such phenomena. In the present work, various polydopamine (PDA) coatings containing chloramine functions were studied. In fact, three PDA-based films were formed by the simple immersion of a gold substrate in a dopamine solution, either at pH 8 in the presence or not of polyethyleneimine (PEI), or at pH 5 in the presence of periodate as an oxidant. These films were characterized by polarization modulation reflection absorption infrared spectroscopy and X-ray photoelectron spectroscopy analyses, and by scanning electron microscopy observations. The chlorination of these PDA films was performed by their immersion in a sodium hypochlorite aqueous solution, in order to immobilize Cl(+I) into the (co)polymers (PDA or PDA–PEI). Finally, antibacterial assays towards the Gram-negative bacteria Escherichia coli (E. coli) and the Gram-positive bacteria Staphylococcus epidermidis (S. epidermidis) were conducted to compare the bactericidal properties of these three N-halamine coatings. Regardless of the bacteria tested, the PDA coating with the best antibacterial properties is the coating obtained using periodate.
      Citation: Colloids and Interfaces
      PubDate: 2022-01-28
      DOI: 10.3390/colloids6010009
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 10: Synthesis and Characterization
           of Chanar Gum Films

    • Authors: Lismet Lazo, Gisela M. Melo, María Luján Auad, Mauricio Filippa, Martin A. Masuelli
      First page: 10
      Abstract: New polysaccharides are being intensely studied as sources of edible materials, with potential application in food packaging systems, eco-materials and the pharmaceutical industry. This investigation aimed to develop biopolymer films based on the polysaccharides obtained from chañar (CH) fruit (Geoffrea decorticans). The resulting polysaccharides, from hydrothermal extraction (CHT) and acid extraction (CHA) were hydrodynamically characterized, with density, viscosity, and diffusion coefficient measurements to obtain their properties in an aqueous solution (intrinsic viscosity, shape factor, partial specific volume, hydration value, molecular weight, and hydrodynamic radius). The polysaccharides films (CHTF and CHAF) were characterized with SEM/EDX, DSC, TGA-DTG, FTIR, DRX, mechanical tests, water vapor permeation, colorimetry, antioxidant capacity, and biodegradability, to determine potential applications based on these properties. The results indicated that the extraction method affects the hydrodynamic properties of the obtained polysaccharide. They differ in molecular weight, and RH of CHT was greater than CHA. Both gums were quasi-spherical, and the νa/b value of CHT was more than CHA. The films properties did not present significant differences in most cases. SEM micrographs illustrate that CHAF presents a much rougher surface. The results of the mechanical analysis show that CHTF has better mechanical properties, it has higher elongation at break and tensile strength, with a Young Modulus of 2.8 MPa. Thermal analysis indicates good thermal stability of the films until about 150 °C. The degradation study shows that CH films are biodegradable in a 35 day range. The study of this properties is critical to demonstrate the functionality of biopolymers and their application. The obtained results represent an advantage and evidence that chañar is an interesting source for extract polysaccharides with film forming properties.
      Citation: Colloids and Interfaces
      PubDate: 2022-02-04
      DOI: 10.3390/colloids6010010
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 11: Wettability and Stability of
           Naproxen, Ibuprofen and/or Cyclosporine A/Silica Delivery Systems

    • Authors: Agnieszka Ewa Wiącek, Kacper Przykaza
      First page: 11
      Abstract: The characteristics of the wetting process of the porous surface of silica gel when penetrated by base liquids (water and n-octane), ethanol and stable drug systems (naproxen, ibuprofen and cyclosporine A), as biologically active substances in two ethanol concentrations, were determined by the wetting rate vs. time. The tests were performed for contacted and non-contacted plates with the vapours of the wetting liquid. Thin-layer liquid chromatography was used to determine the penetration rate of the SiO2-coated plates, taking into account the linear dependence consistent with the Washburn equation. Additionally, the changes in the adhesive tension ΔG were determined for the tested drugs. Drug stability tests were conducted using the dynamic light scattering technique and microelectrophoresis. The penetration time of the plate depends on the properties and structure of the wetting liquid droplets. The types of interactions (dispersive, electrostatic and hydrogen bonding) formed between the silanol surface groups of the silica gel and the groups contained in the adsorbate particles are also very important factors. The greater the impact force, the slower the wetting process due to the strong penetration of the liquid into the pores of the substrate. The characteristics of the drug wetting/stability process may contribute to the development of their new forms, creating delivery systems with greater efficiency and lower side effects.
      Citation: Colloids and Interfaces
      PubDate: 2022-02-06
      DOI: 10.3390/colloids6010011
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 12: Oil Droplet Coalescence in
           W/O/W Double Emulsions Examined in Models from Micrometer- to
           Millimeter-Sized Droplets

    • Authors: Nico Leister, Chenhui Yan, Heike Petra Karbstein
      First page: 12
      Abstract: Water-in-oil-in-water (W1/O/W2) double emulsions must resist W1–W1, O–O and W1–W2 coalescence to be suitable for applications. This work isolates the stability of the oil droplets in a double emulsion, focusing on the impact of the concentration of the hydrophilic surfactant. The stability against coalescence was measured on droplets ranging in size from millimeters to micrometers, evaluating three different measurement methods. The time between the contact and coalescence of millimeter-sized droplets at a planar interface was compared to the number of coalescence events in a microfluidic emulsion and to the change in the droplet size distributions of micrometer-sized single and double emulsions. For the examined formulations, the same stability trends were found in all three droplet sizes. When the concentration of the hydrophilic surfactant is reduced drastically, lipophilic surfactants can help to increase the oil droplets’ stability against coalescence. This article also provides recommendations as to which purpose each of the model experiments is suited and discusses advantages and limitations compared to previous research carried out directly on double emulsions.
      Citation: Colloids and Interfaces
      PubDate: 2022-02-08
      DOI: 10.3390/colloids6010012
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 13: Electric Fields Enhance Ice
           Formation from Water Vapor by Decreasing the Nucleation Energy Barrier

    • Authors: Leandra P. Santos, Douglas S. da Silva, André Galembeck, Fernando Galembeck
      First page: 13
      Abstract: Video images of ice formation from moist air under temperature and electric potential gradients reveal that ambient electricity enhances ice production rates while changing the habit of ice particles formed under low supersaturation. The crystals formed under an electric field are needles and dendrites instead of the isometric ice particles obtained within a Faraday cage. Both a non-classical mechanism and classical nucleation theory independently explain the observed mutual feedback between ice formation and its electrification. The elongated shapes result from electrostatic repulsion at the crystal surfaces, opposing the attractive intermolecular forces and thus lowering the ice-air interfacial tension. The video images allow for the estimation of ice particle dimensions, weight, and speed within the electric field. Feeding this data on standard equations from electrostatics shows that the ice surface charge density attains 0.62–1.25 × 10−6 C·m−2, corresponding to 73–147 kV·m−1 potential gradients, reaching the range measured within thunderstorms. The present findings contribute to a better understanding of natural and industrial processes involving water phase change by acknowledging the presence and effects of the pervasive electric fields in the ambient environment.
      Citation: Colloids and Interfaces
      PubDate: 2022-02-09
      DOI: 10.3390/colloids6010013
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 14: Characterization of the
           Dissolution of Water Microdroplets in Oil

    • Authors: Tamás Gerecsei, Rita Ungai-Salánki, András Saftics, Imre Derényi, Robert Horvath, Bálint Szabó
      First page: 14
      Abstract: Water in oil emulsions have a wide range of applications from chemical technology to microfluidics, where the stability of water droplets is of paramount importance. Here, using an accessible and easily reproducible experimental setup we describe and characterize the dissolution of water in oil, which renders nanoliter-sized droplets unstable, resulting in their shrinkage and disappearance in a time scale of hours. This process has applicability in creating miniature reactors for crystallization. We test multiple oils and their combinations with surfactants exhibiting widely different rates of dissolution. We derived simple analytical equations to determine the product of the diffusion coefficient and the relative saturation density of water in oil from the measured dissolution data. By measuring the moisture content of mineral and silicone oils with Karl Fischer titration before and after saturating them with water, we calculated the diffusion coefficient of water in these two oils.
      Citation: Colloids and Interfaces
      PubDate: 2022-02-14
      DOI: 10.3390/colloids6010014
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 15: Lysozyme Influence on
           Monolayers of Individual and Mixed Lipids

    • Authors: Juan Torrent-Burgués
      First page: 15
      Abstract: Fatty acids, cholesterol, and phospholipids are amphiphilic compounds of biological interest, which form ordered monolayers mimicking biomembranes, and can be studied with the Langmuir technique using surface pressure-area isotherms and compressibility plots. Proteins are also components of biomembranes or are present in body fluids. In this study, the influence of lysozyme on different films of a fatty acid (stearic acid or oleic acid), cholesterol, a phospholipid (dipalmitoylphosphatidylcholine, DPPC, or palmitoyloleoylphosphatidylcholine, POPC), and mixtures of them is presented using a 0.9% saline solution as subphase. Results show that the presence of lysozyme alters the lipid monolayer formation in an important way at the beginning (low surface pressures) and the middle (intermediate surface pressures) parts of the isotherm. At high surface pressures, the phospholipids DPPC and POPC and the saturated fatty acid, stearic acid, expel lysozyme from the surface, while oleic acid and cholesterol permit the presence of lysozyme on it. The mixtures of oleic acid-DPPC also expel lysozyme from the surface at high surface pressures, while mixtures of oleic acid-POPC and cholesterol-POPC permit the presence of lysozyme on it. The compressibility of the monolayer is affected in all cases, with an important reduction in the elastic modulus values and an increase in the fluidity, especially at low and intermediate surface pressures.
      Citation: Colloids and Interfaces
      PubDate: 2022-02-21
      DOI: 10.3390/colloids6010015
      Issue No: Vol. 6, No. 1 (2022)
       
  • Colloids and Interfaces, Vol. 6, Pages 16: Polymeric Surfactant
           P84/Polyoxometalate α-PW12O403−—A Model System to
           Investigate the Interplay between Chaotropic and Hydrophobic Effects

    • Authors: Philipp Schmid, Xaver Graß, Pratap Bahadur, Isabelle Grillo, Olivier Diat, Arno Pfitzner, Pierre Bauduin
      First page: 16
      Abstract: Low charge density nanometric ions were recently shown to bind strongly to neutral hydrated matter in aqueous solution. This phenomenon, called the (super-)chaotropic effect, arises from the partial dehydration of both the nano-ion and the solute, leading to a significant gain in enthalpy. Here, we investigate the chaotropic effect of the polyoxometalate α-PW12O403− on the triblock copolymer P84: (EO)19(PO)43(EO)19 with (EO)19 the polyethoxylated and (PO)43 the polypropoxylated chains. The combination of phase diagrams, spectroscopic (nuclear magnetic resonance) and scattering (small angle neutron/X-ray scattering) techniques revealed that: (i) below the micellization temperature of P84, PW12O403− exclusively binds to the propylene oxide moiety of P84 unimers; and (ii) above the micellization temperature, PW12O403− mostly adsorbs on the ethylene oxide micellar corona. The preferential binding of the PW12O403− to the PPO chain over the PEO chains suggests that the binding is driven by the chaotropic effect and is reinforced by the hydrophobic effect. At higher temperatures, copolymer micellization leads to the displacement of PW12O403− from the PPO chain to the PEO chains. This study deepens our understanding of the subtle interplay between the chaotropic and hydrophobic effects in complex salt-organic matter solutions.
      Citation: Colloids and Interfaces
      PubDate: 2022-03-01
      DOI: 10.3390/colloids6010016
      Issue No: Vol. 6, No. 1 (2022)
       
 
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