Ion exchange membranes based upon crosslinked sulfonated polyethersulfone for electrochemical applications

Synthesis and characterization of new ion exchange membranes made from chlorosulfonated polyethersul- fone (SO2Cl-PES) crosslinked by polyaminated crosslinking reagents have been performed. Two examples are described: one crosslinked by hexane diamine, the other by amino-polyethersulfone (NH2-PES). Sulfonated polyether sulfone (S-PES) and NH2-PES have similar chemical structures that allow compatibility. Surpris- ingly enough, better results were obtained using amino-polyethersulfone. The best results have been obtained using SO2Cl-PES with 1.3 SO2Cl group per monomer unit crosslinked by 0.2 equivalent of NH2-PES. The membranes, less brittle than pristine SPES and insoluble in solvents such as DMAc, were characterized by TGA, DMA, DSC, ionic conductivity, transport numbers, and water swelling. The results showed that these membranes presented very promising performances for use in Proton Exchange Membrane Fuel Cells

Production and Characterization of Phospholipases C from some Bacillus thuringiensis Isolates Recovered from Egyptian Soil

Two hundred and thirty one isolates, with the characteristic morphology of Genus Bacillus, were recovered from 100 soil samples collected from 7 different Egyptian governorates, and were screened for phospholipase C (PLC) production by egg-yolk plate method. Sixty isolates have shown very high PLC production and were further assessed using chromogenic assay method. The highest five producers, identified by 16S rRNA gene sequencing as Bacillus thuringiensis, were selected and their PLCs were purified to homogeneity using ammonium sulfate precipitation and Sephadex G-75 gel filtration chromatography. PLCs had molecular masses of 28.5 kDa as indicated by SDS-PAGE. The characteristics of the studied five PLCs were having maximal activities at 35-45°C and pH 7.2. The enzymes could retain more than half of their maximum activities at 30-60°C and pH 7-8. Equivalent activities were recorded at low water tension. PLC from B. thuringiensis KT159186 was relatively thermostable with a maximum activity at 40°C. The half-inactivation temperature was above 50°C, which compared favorably to that of other enzymes. Activity at the wide temperature range (20-80°C) was high (about 50% of maximum),. This PLC could tolerate pH as high as 12 with only 30% loss of activity. Specificity pattern of PLC from the same isolate showed equivalent activities toward phosphatidylcholine and phosphatidylinositol in addition to marked activity toward phosphatidylethanolamine, which makes it a typical non-specific PLC for industrial purposes. In conclusion, these characteristics of PLC from the test isolate make it attractive for various industrial applications

A novel fast time jamming analysis transmission selection technique for radar systems

The jamming analysis transmission selection (JATS) sub-system is used in radar systems to detect and avoid the jammed frequencies in the available operating bandwidth during signal transmission and reception. The available time to measure the desired frequency spectrum and select the non-jammed frequency for transmission is very limited. A novel fast time (FAT) technique that measures the channel spectrum, detects the jamming sub-band and selects the non-jammed frequency for radar system transmission in real time is proposed. A JATS sub-system has been designed, simulated, fabricated and implemented based on FAT technique to verify the idea. The novel FAT technique utilizes time-domain analysis instead of the well-known fast Fourier transform (FFT) used in conventional JATS sub-systems. Therefore, the proposed fast time jamming analysis transmission selection (FAT-JATS) sub-system outperforms other reported JATS sub-systems as it uses less FPGA resources, avoids time-delay occurred due to complex FFT calculations and enhances the real time operation. This makes the proposed technique an excellent candidate for JATS sub-systems

Superimposed structure in the southern periphery of Abu Gharadig Basin, Egypt: Implication to petroleum system

South West Abu-Sennan (SWS) area near the southern periphery of the Abu-Gharadig petroliferous basin in the Egyptian Northern Western Desert is an important hydrocarbon field characterized by being a multi-reservoir with a complex structural architecture. Therefore, in this study, we illustrated the regional structural role that facilitated having Jurassic mature source rocks (Masajid and Khatatba formations) through surgical seismic interpretation and observed the controlling petroleum system of the study area using a set of 20 seismic lines and 4 wells data. The study resulted in having the SWS oil field controlled by a strike-slip movement that occurred during the Upper Cretaceous time accompanying the African Plate movement against the Eurasian Plate superimposing an ENE–WSW strike-slip fault zone in the region and a strong pattern of NW–SE-oriented faults due to numerous phases of extension. The associated structures include horsts, normal fault propagation folds, and strike-slip-related anticlines. The strike-slip tectonics played a major role in forming entrapment for the Jurassic expelled hydrocarbons. The seismic horizons flattening exercise performed on AR/G member and Khoman Formation demonstrated that the main reason for not having hydrocarbon accumulations in the Jurassic levels in the study area is that the trap configuration was ready to accumulate hydrocarbon but after the hydrocarbon generation and migration time. The study concluded that the hydrocarbons migrated along the faults which cut deeply to the source rocks and entrapped in the possible cretaceous reservoirs during the late cretaceous time. The conducted workflow in this study can be utilized to better explore and develop cretaceous reservoirs in the study and neighbouring areas

Antimicrobial, Antibiofilm and Immunomodulatory Activities of Lactobacillus rhamnosus and Lactobacillus gasseri against some Bacterial Pathogens

In this study, two Lactobacillus (LAB) strains namely, Lactobacillus rhamnosus EMCC 1105 (L. rhamnosus) and Lactobacillus gasseri EMCC 1930 (L. gasseri) were tested for their antagonistic activities against Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) which are known to be frequently implicated in biofilm infections. The acidic cell free culture supernatant (CFS) of 24 h and 48 h cultures of both LAB stains showed antimicrobial effects against the three pathogens in radial diffusion assay. These effects were abolished upon neutralization of CFS indicating that this effect was due to acids only. Both LAB strains could effectively inhibit the biofilm formation of the three test pathogens and largely replaced them on polystyrene surfaces as demonstrated by crystal violet staining, viable count and scanning electron microscopy. Both of the tested LAB strains could inhibit the protease productivity of S. aureus in 24 h and 48 h dual species-biofilms. The supernatant of 24 h-dual biofilms of P. aeruginosa with L. gasseri also showed a significantly lower protease activity compared to that of P. aeruginosa individual biofilm. Neither LAB strains affected phospholipase C production by the test pathogens when they co-exist during biofilm formation. The different preparations of LAB strains caused no significant change in the levels of gamma interferon expressed by peripheral blood mononuclear cells in response to stimulation by the test pathogens in vitro. In conclusion, L. gasseri and L. rhamnosus can be considered as promising tools for combating biofilm infections

Finite Time Stabilization of the Four Tanks System: Extensions to the Uncertain Systems

We consider the finite time stability and stabilization of linear systems described in continuous time. First, we provide a condition for the stability over time using the state transition matrix standard. Then we give conditions to design a state feedback control that stabilizes the system over time. In some cases where there is uncertainty in the system model, the previous conditions are extended to a certain class of uncertain systems. The considered uncertainties are the polytopic and norm bounded ones. To reveal the proposed approach, an application to the four tanks system was made

New ion exchange membrane derived from sulfochlorated polyether sulfone for electrodialysis desalination of brackish water

The purpose of this work is to study the desalination of brackish water using a new ion exchange membrane, made from sulfochlorated polyethersulfone (Cl-PES), and crosslinked using aminated polyethersulfone (NH2-PES) as a crosslinking reagent. This membrane, named ClNH2 membrane, has been obtained by reaction between Cl-PES with 1.3 SO2Cl groups per monomer unit and 0.2 equivalent amount of NH2-PES. ClNH2 membrane has been characterized in terms of contact angle, transport number, intrinsic conductivity, and water uptake (as a function of temperature). Electrodialysis performances of the newly synthetized membranes have been measured using an electrodialysis cell at a laboratory scale and compared to commercial membranes. All the experiments have been performed using synthetic brackish water solutions prepared from sodium chloride salts with different concentrations (varying from 0.5 to 5.0 g/L). The concentration of different water samples obtained has been found to be below the amount recommended by the World Health Organization (WHO) for drinking water.ERAS Labo; World Health Organizatio

Synthesis and characterization of new membranes deriving from sulfonated polyethersulfone for PEMFC applications

Two new types of proton exchange membranes used in proton exchange membrane fuel cell (PEMFC) were synthesized from sulfochlorinated polyethersulfone (PES (polyarylethersulfone)–SO2Cl). One, called S-PESB, was obtained by grafting butylphenol in an amount of 0.3 equivalent per monomer unit. The second (S-PESTD) was prepared by cross-linking with 0.1 equivalent of 4,7,10-trioxa-1,13-tridecandiamine. Analysis of thermal properties (thermogravimetric analysis and DSA) and mechanical testing (dynamical and thermomechanical analysis) of the two membranes showed a significant improvement in comparison with unmodified polyethersulfone sulfonic acid (S-PES). Thus, a significant lowering of the glass transition temperature was observed. In addition, a comparative study carried out with the commercial Nafion® membrane gave very similar values of ionic conductivity and a high selectivity of proton transport. A preliminary electrochemical study of membrane/electrode assembly has shown that the elaborated membranes are promising in PEMFC application. Power densities obtained with cross-linked S-PESTD were superior to those of commercial Nafion®, while S-PESB led to comparable values

Crosswell Seismic Amplitude-Versus-Offset for Detailed Imaging of Facies and Fluid Distribution within Carbonate Oil Reservoirs

Crosswell seismic surveys were conducted at two fields in northern Michigan. One of these, Springdale, included two monitor wells that are located external to the reef, and the other, Coldspring, employed two production wells within the reef. The Springdale wells extended to much greater depths than the reef, and imaging was conducted from above and from beneath the reef. The resulting seismic images provide the best views of pinnacle Niagaran reefs obtained to date. The tops of the reservoirs can be clearly distinguished, and their lateral extent or dipping edges can be observed along the profile. Reflecting events internal to the reef are evident; some of them are fairly continuous across the reef and others are discontinuous. Inversion of the seismic data indicates which events represent zones of higher porosity and which are lower porosity or even anhydrite plugged. The full stacked image includes angles that are beyond critical for many of the interfaces, and some reflections are visible only for a small range of angles, presumably near their critical angle. Stacking these angles in provides an opportunity for these events to be seen on the stacked image, where otherwise they would have been unrecognized. For inversion, however, the complexity associated with phase changes beyond critical can lead to poor results, and elastic inversion of partial angle stacks may be best conducted with restrictions to angles less than critical. Strong apparent attenuation of signals occurs when seismic ray paths pass through the upper part of the Springdale reservoir; this may be due to intrinsic attenuation and/or scattering of events due to the locally strongly varying gas saturation and extremely low fluid pressures. Signal-to-noise limitations become evident far from the source well in the Coldspring study, probably because the raw data were strongly affected by tube-wave noise generated by flow through the perforation of the receiver well. The seismic images obtained, and interpretations of them, as assisted by Amplitude-versus-Angle studies and accompanying inversion, provide additional insight into the internal geometry of these two reefs and provide data that should be useful for reservoir management