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Search Results: 1 - 10 of 312 matches for " hydrophobic "
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Soot and Nanomaterials Synthesis in the Flame  [PDF]
Z. Mansurov
Journal of Materials Science and Chemical Engineering (MSCE) , 2014, DOI: 10.4236/msce.2014.21001

The general scheme of conversion of hydrocarbon fuels with new experimental data on the formation of fullerenes and graphenes taking into account the pressure effect is proposed for the fuel-rich flames. It is shown that the formation of fullerenes is important to the corresponding spatial orientation of PAH, possible at low pressures. The formation of hydrophobic soot surface on silicon and nickel substrates during combustion of propane-oxygen flame was studied. It is established that the hydrophobic properties are due to the presence of soot particles in the form nanobeads. The photovoltaic properties of solar cells coated by nickel oxide nanoparticles synthesized in counter flow propane-air flame. It is revealed that coated the surface of a silicon solar cell by nickel oxide nanoparticles results in the increase in solar cell efficiency by 3%.

Effect of the Position of Reaction-Site in Amphipathic-Type Thioester in Aqueous Amidation Reaction  [PDF]
Ikumi Otomo, Chiaki Kuroda
Advances in Chemical Engineering and Science (ACES) , 2015, DOI: 10.4236/aces.2015.53032
Abstract: Amphipathic-type thioesters CH3(CH2)mCOS(CH2)nCOONa (m + n = 12) were synthesized and their reaction with various alkylamines was examined. Compounds having thioester moiety close to carboxylate (m = 10, n = 2) afforded the corresponding amides in good yields, while the substrate having thioester moiety distant from carboxylate (m = 2, n = 10) afforded the amides in relatively low yield. In all cases, the difference in yield due to the chain length of amine was not observed. The results indicated that the reaction took place effectively near the surface of micelle. However, the reaction was found to occur not only on micelle surface but also in solution.
Chemical and Morphological Surface Modification of Epoxy Based Thermosets  [PDF]
Marcela E. Penoff, Patricia A. Oyanguren, Wido Schreiner, Pablo E. Montemartini
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.47A2001

Recently developed low fluorine containing polymers are advanced materials which confer advantageous properties to surfaces at a lower cost than conventional fluoropolymers (like PTFE), and are also more easily processable. Fluoropolymer surfaces are characterized by a low surface energy, high oleo and hydrophobicity, low coefficients of friction, among many other properties. This makes them desired materials in microelectronics, antifogging, antifouling and medical applications, to name a few. Fluorinated compounds are not easily coupled with macromolecules or common organic systems, and great efforts are made to compatibilize fluorinated species with hydrocarbon polymers. In this work, two chemical routes were explored in order to incorporate perfluorinated alkyl chains in an epoxy-amine based thermoset. On one side, a perfluoroalkyl thiolated molecule was used as a stabilizing ligand for silver nanoparticles, which were incorporated in the matrix polymer. On the other hand, fluorinated chains containing epoxy functionalities, were used as the matrix modifier. In the first case, fluorinated chains covering the nanoparticles, were mixed with the matrix, while in the second case, the fluoroalkyl chains were chemically linked to the network. Fluorine migration to the airpolymer interface was confirmed by X-Ray photoelectron spectroscopy (XPS). The materials hydrophobicity was then studied in terms of their contact angle with water (CA), as a function of the surface composition and the topography. Scanning electron microscopy (SEM) and atomic force microscopy (AFM), operated in moderate and light tapping modes, were used to morphologically describe the surfaces. An exhaustive surface analysis was made in order to explain the different hydrophobicity grades found.


Theory of cold denaturation of proteins  [PDF]
Arieh Ben-Naim
Advances in Biological Chemistry (ABC) , 2013, DOI: 10.4236/abc.2013.31005

A new approach to the problem of cold denaturation is presented. It is based on solvent-induced effects operating on hydrophilic groups along the protein. These effects are stronger than the corresponding hydrophobic effects, and they operate on the hydrophilic groups which are plentiful than hydrophobic groups. It is shown that both heat and cold denaturation can be explained by these hydrophilic effects.

Genetic Algorithm Optimization for Multi-Biogas Mass Transfer in Hydrophobic Polymer Biocell  [PDF]
Ahmad Qasaimeh, Talal Masoud, Hesham Al Sharie
Journal of Sustainable Bioenergy Systems (JSBS) , 2015, DOI: 10.4236/jsbs.2015.53007
Abstract: In this work, a new municipal biocell with new operation and waste management is proposed. The proposed system is biocell that is built gradually when the waste is being disposed. Different from conventional disposal at landfills, waste is put between “hydrophobic bricks” that are perforated permeable containments filled up with porous dumping material such as styrofoam. Genetic algorithm is used to optimize a transfer function that represents input of biogas percentages and output solutions for daily mass transfer rates for biogas mixture from which mass and volume of biogas within the biocell time of service are calculated. Transfer function is obtained by fitting dynamic input-output data to the input-output solutions. Input-output data are encoded to chromosomes (1, 0 digits). These chromosomes are subjected to genetic processes as crossover and mutations. Then a process of evaluation takes place. The evaluation process entails an objective function that evaluates the squared difference between experimental and calculated values. After the chromosomes are being evaluated, they are either selected for more iteration or decoded to the solutions. The decoding process is performed on optimal chromosomes to obtain optimal solutions and required optimal transfer function. Consequently, the mass and volume of biogas within the landfill time of service are determined for any ratio of CH4:CO2 in biocell.
Influence of Small Amphiphiles on Aqueous Dispersions of β-Lactoglobulin A and Bovine Serum Albumin: (1) Intermolecular Interactions  [PDF]
Zahur Z. Haque, Guichard L. Bohoua
Food and Nutrition Sciences (FNS) , 2015, DOI: 10.4236/fns.2015.612117
Abstract: Hydrophilic and hydrophobic (φ) interactions among amphiphiles play critical roles in interfacial properties of proteins and other smaller amphiphiles and affect the creation and stability of foams and emulsions in food systems. Contribution of small amphiphiles on H-bonding and hydrophobic (φ) interactions at a model interface comprising of a water-hydrophobized surface interface as reflected by contact angle (θ) of fatty acid free bovine serum albumin (FAF-BSA), bovine serum albumin (BSA), and β-lactoglobulin variant A (β-LGA) was investigated. Amphiphiles were used with either protein in neutral water or α-bromonaphtalene (α-BrN) (22°C) to obtain θ-H2O and θ-α-BrN measurements, respectively. θ-α-BrN reflected influence of φ-interactions on θ since α-BrN molecules do not partake significantly in H-bonding. Ionic nature of the amphiphiles had no significant effect. Dramatic difference was between zwitterionic Z8 and Z12. At 1%, Z8 significantly increased H-bonding in BSA and β-LGA by 26% and 55%, respectively, whereas Z12, which is more hydrophobic, decreased it by 50% and 21%. At the same concentration, φ-interactions were enhanced by Z8 for BSA by 37% and by all amphiphiles except Z12 for FAF-BSA.
International Journal of Engineering Science and Technology , 2012,
Abstract: Nanobubble is a mystery in terms of stability and longevity. Nanobubble, now directly imaged by tapping mode atomic force microscopy or by dynamic light scattering, were previously inferred from long ranged attraction between hydrophobic surfaces immersed in water. They exists in an interconnected, irregular and closed pack structure whose lifetime is in order of hours and whose morphology is dependent upon the pH.
Fuzzy oil drop model verified positively
Mateusz Banach,Katarzyna Prymula1, 3,Leszek Konieczny1, 4,Irena Roterman
Bioinformation , 2011,
Abstract: The “fuzzy oil drop” model assuming the structure of the hydrophobic core of the form of 3-D Gauss function appeared to be verified positively. The protein 1NMF belonging to downhill proteins was found to represent the hydrophobic density distribution accordant with the assumed model. The accordance of the protein structure with the assumed model was measured using elements of theory information. This observation opens the possibility to simulate the folding process as influenced by external force field of hydrophobic character.
Development of Electrochromic Devices Working with Hydrophobic Lithium Electrolyte
Nam-Gyu Park,Armel Poquet,Guy Campet,Josik Portier
Active and Passive Electronic Components , 1998, DOI: 10.1155/1998/67830
Shipra Duggal et al.
International Journal of Pharmaceutical Sciences and Research , 2012,
Abstract: Various types of lipid based vesicular systems have been developed in controlled and targeted drug delivery. Self assembled nanoparticles (SAN) has advantages over traditional colloidal vesicular systems and also avoids some of their major disadvantages. SAN made of solid lipids are submicron colloidal carriers (50-1000nm). These consist of a solid hydrophobic core having a monolayer of phospholipid coating. The solid core contains drug dissolved or dispersed in the solid high melting fat matrix. The hydrophobic chains of phospholipids are embedded in the fat matrix. The outstanding characteristic of SAN is that they are nearly or wholly composed of ampiphillic prodrug. Serious drawbacks of the drugs could be effectively circumvented by covalent linkage of the drug to fatty acids. These lipidic prodrugs, if provided with some surface active property, tend to form supramolecular assemblages in aqueous media. They provide an efficient method for delivery of drugs directly to the targeted site, leading to reduction of drug toxicity with no adverse effects and also reduces the cost of therapy by imparting better biopharmaceutical properties to the drug, resulting in improved bioavailability, especially in case of poorly soluble drugs. This articles reflects the various types of drug carrier systems and various method of preparation of self assembeled nanoparticles and also characterized the SAN for different attributes.
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