Foaming binary solution mixtures of low molecular surfactant and polyelectrolyte

The lifetime of water solution foams of sodium dodecylsulfate (DDS, low molecular weight surfactant) and sodium carboxymethylcellulose (SCMC, polyelectrolyte) and their binary mixtures was experimentally investigated. The effects of ionic strength and acidity on the foam life were also determined. In binary solutions, a synergic effect of DDS and SCMC on the surface tension reduction, most likely resulting from the interaction of the surfactant with polymer, was found. The addition of NaCl into solution or increasing the ionic strength was found to decrease the surface tension and reduce interfacial mobility, hence increased foam lifetime. The relatively low lifetime of binary solution foams in acidic medium was attributed to the reaction between SCMC and acid, which resulted in relatively small reductions in the viscosity and consequently lowered the solution viscosity

Network Performance Evaluation of Abis Interface over DVB-S2 in the GSM over Satellite Network

This paper deals with establishing a GSM link over Satellite. Abis interface, which is defined between Base Transceiver Station (BTS) and Base Station Controller (BSC), in a GSM network is considered here to be routed over the Satellite. The satellite link enables a quick and cost-effective GSM link in meagerly populated areas. A different scenario comparison was done to understand the impact of Satellite environment on network availability comparing to terrestrial scenario. We have implemented an Abis interface over DVB S2 in NS2 and evaluated the performance over the high delay and loss satellite channel. Network performance was evaluated with respect to Satellite channel delay and DVB S2 encapsulation efficiency under different amount of user traffic and compared with the terrestrial scenario. The results clearly showed an increased amount of SDCCH and TCH channels required in the case of satellite scenario for the same amount of traffic in comparison to conventional terrestrial scenario. We have optimized the parameters based on the simulation results. Link budget estimation considering DVB-S2 platform was done to find satellite bandwidth and cost requirements for different network setups

Composite Biosorbents of Metal Ions Based on Yeast Cells and Diatomite

The possibility of removing Cu2+ and Pb2+ ions from solutions by the yeast cells Rhodotorula glutinis and diatomite (natural mineral) was studied. It is shown that at the concentration of CuSO4 and Pb(NO3)2 10-3 mol/l the removal of metal ions by yeast cells was 59.1 and 72.4% for the ions of Cu2+ and Pb2+. The yeast cells surface includes amino, hydroxyl, phosphate and carboxyl groups which activates sorption ability, because these groups can bind metal ions by ion exchange, donor acceptor and electrostatic interactions. The removal degree of metal ions by diatomite under the same conditions was for Cu2+ 91.6% and for Pb2+ 94.7%. To increase the removal degree of metal ions from solutions, the yeast cells were immobilized on the surface of diatomite. In order to attach the negatively charged cells of microorganisms with negatively charged surface of the mineral, the surface of diatomite was modified by polyethylenimine (PEI). As a result, the immobilization degree of Rhodotorula glutinisto the surface of diatomite at the concentration of PEI 0.02 base-mol/l increased from 62 to 88%, which is explained by the existence of electrostatic contacts between the negatively charged functional groups of the cell surface and amino groups of PEI, that has covered the surface of diatomite by PEI. It is shown that the obtained composite biosorbent removes 97.8% of Cu2+ ions and 99.4% of Pb2+ ions

Nanoparticles of Sulfur as Fungicidal Products for Agriculture

Sulfur is a nonmetallic element necessary for life. Sulfur nanopartieles display unique physical and chemical feature because of effects such as the quantum size effect, mini size effect, surface effect and macro-quantum tunnel effect. So sulfur nanoparticles would present higher efficacies such as removal of heavy metals, radical-scavenging, antimicrobial activity, antioxidant and antitumor activities. It is used as a fungicide product in agriculture, also used in medicine, to obtain sulfur fertilizers and cosmetics industries, as well as in obtaining nanocomposite lithium batteries. In synthesis of sulfur nanowires with carbon to from hybrid materials with useful properties for gas sensor and catalytic applications. This work presents the results of obtaining the sulfur nanoparticles, which can be used in agriculture as a fungicide treatment. Sulfur nanoparticles were obtained by modifying the surface of sulfur by various surfactants including cetyltriammoniumbromide (CTABr), Sulfanol, Sodium Ligninsulfonate (CMN), Sodium salt of polynaphthalene sulphonic acid (NNO), water soluble polymer sodium carboxymethylcellulose (NaCMC), mineral mixtures and their compositions. The size and the structure of sulfur nanoparticles were determined by methods as LSA, XRD, SEM. Been studied the value of adsorption at the interface of solid/gas. It is shown that the nanoparticles have a sulfur monoclinic B-form, and their average size is in the range 500-1000 nm. The received products can be considered as perspective forms of application in agriculture

Aggregation of Aqueous Kaolin Suspensions in the Presence of Cationic Polyelectrolytes, Anionic Polyelectrolytes and their Mixtures

The influence of anionic, cationic synthetic polyelectrolytes and their mixtures on the aggregation of kaolin hydrosuspension has been studied by means of spectrophotometry, electrophoresis and dynamic light scattering (DLS). An enhancement of the flocculating property of the cationic polyelectrolyte FO 4650 in accordance with its consumption increases from 0.77 mg/g to 7.7 mg/g has been found. At these conditions the relative size of floccules (R) increases from 1.0 to 13.0. The increase of the flocculating property accordingly to the increasing charge of anionic polyelectrolyte is observed in mixtures of cationic and anionic polyelectrolytes. The time dependences of R in presence of the weakly charged cationic polyelectrolyte mixtures reach a plateau region. This can be associated with the formation of electrostatic contacts between the solid surface and the polymer mixtures, as well as with stabilizing equilibrium conformation of macromolecules. It has been found that mixtures of oppositely charged polyelectrolytes lead to more efficient aggregation of particles than individual polyelectrolytes. This process is enhanced by the introduction primarily of the cationic polyelectrolyte and then the anionic one (R = 6‒10). Use of the preformulated mixtures of polymers leads to the marked increase in degree of particle aggregation (R = 12). The reason is an interaction of kaolin particles with inter-polymer complex formed by electrostatic attraction of oppositely charged polyelectrolytes

A Research of Colloidal Silver Immobilization in Bionanocomposites of Natural Polymers and Montmorillonite

Currently, colloidal silver particles are used in the creation of electronic, optical, and sensor devices of a new generation. Silver-containing bionanocomposites (BNCs) were synthesized by immobilization of colloidal montmorillonite particles containing colloidal silver in a composition of sodium alginate and sodium salt of carboxymethylcellulose. Silver-containing montmorillonite particles Ag-Mt were obtained by replacing Na+ ions in layered silicate galleries with Ag+ ions, followed by the transformation of silver ions into silver particles. The introduction of Ag+ ions into the montmorillonite structure is justified by infrared spectroscopy. When studying the strength of bionanocomposite films, it was found that with an increase in the content of Ag-Mt particles in their composition, the strength increases and the deformation decreases.It is found that the equilibrium values of the swelling constant are set in ~30 minutes. At the same time, with an increase in the Ag-Mt content in the bionanocomposite from 3 % to 10 %, the value of the equilibrium swelling coefficient (Kswell) decreases by 2.8 times. The replacement of Na+ ions with Ag+ ions in the montmorillonite structure is accompanied by a decrease in the swelling of bionanocomposites, which is explained by the lower hydration of Ag+ ions compared to Na+ ions. As another reason for the decrease in the swelling of bimonanocomposites with an increase in the proportion of Ag-Mt in their composition, enhancing their ability to structure formation in the prersence of a clay mineral is indicated.The kinetics of the release of Ag+ ions from bionanocomposites into saline has been studied. It is shown that the release of Ag+ ions increases with increasing pH of the mediu

Preparation and Regulation of Structural-mechanical Properties of Biodegradable Films Based on Starch and Agar

The problem of recycling polymer waste is one of the most actual problems. One way to solve this problem is to create biodegradable food packaging. By mixing solutions of starch and agar at different mass ratios of polymers in the presence of glycerol, biodegradable films are obtained. Their structural and mechanical characteristics are determined. It is shown that the values of strength, modulus of elasticity and puncture resistance of films are maximal at the mass ratio of agar/starch 7-9. A comparison of the roughness of the films obtained from starch, agar and their mixture showed that the greatest roughness is possessed by films based on starch. The introduction of agar into the films of starch leads to a significant reduction in their roughness.To regulate the structural and mechanical properties of films, it is proposed to use Cа and Mg salts. The influence of Ca2+ and Mg2+ ions on the strength and deformation characteristics of biofilms was studied. It is shown that Ca2+ ions monotonically increase the strength characteristics of starch-agar films, while the curves of changes in these parameters in the presence of Mg2+ ions have maxima at a concentration of 0.5 %. The difference in the effect of Ca2+ and Mg2+ ions on the structural and mechanical properties of films is explained by the hydration degree of these ions.The biodegradability of starch-agar films was controlled by changing their IR spectra. The most significant changes are observed in the intensity and localization of peaks corresponding to O-H, C-H and C-C bonds, which can be evidence of changes in the structure of films due to the destruction of the grid of hydrogen bonds and hydrophobic interactions, as well as the break of hydrocarbon chains and the destruction of the skeleton of carbohydrate molecules