Carboxymethylcellulose/polyaniline blends. Synthesis and properties

Summary Polyaniline (PANI) as one of the conducting polymers focuses intensive research on both scientific and practical field. There are quite a lot of known hybrid materials of PANI and other polymer systems with various synthetic polymers, which results in blends with various properties. The presented research covers the blends of polyaniline with semisynthetic (carboxymethyl) cellulose (CMC). The system could lead to a new antielectrostatic material with interesting properties and seems to be applicable as an additive for packaging in both food and non-food industry. The final material was obtained using both protonated (HCl) and deprotonated form of polyaniline in its semi-oxidized form of leucoemeraldine. Blending consisted in obtaining of thin layer by slow evaporation of the solvent from a mixture of PANI and CMC. For the main investigation atomic force microscopy (AFM) in non-contact mode was used, which gave the topological information about the surface and also some structural information about the material. The described process seems to be very interesting as a route for obtaining a new hybrid natural/synthetic material with very interesting properties and a potential for application.     

Tuning space mapping: The state of the art

The electromagnetic (EM)‐simulator‐based tuning process for rapid microwave design can combine EM accuracy with circuit‐design speed. Our own approach is based on the intuitive engineering idea of “space mapping.” In this article, we explain the art of microwave design optimization through “tuning space mapping” procedures. We list various appropriate types of models (called “surrogates”). We demonstrate the implementation of these surrogates through a simple bandstop filter. We provide application examples using commercial simulation software. Our purpose is to help microwave engineers understand the tuning space mapping methodology and to inspire new implementations and applications. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22: 639–651, 2012.     

Novel Hydrogen Sulfide (H2S)-Releasing BW-HS-101 and Its Non-H2S Releasing Derivative in Modulation of Microscopic and Molecular Parameters of Gastric Mucosal Barrier

Hydrogen sulfide (H₂S) is an endogenously produced molecule with anti-inflammatory and cytoprotective properties. We aimed to investigate for the first time if a novel, esterase-sensitive H₂S-prodrug, BW-HS-101 with the ability to release H₂S in a controllable manner, prevents gastric mucosa against acetylsalicylic acid-induced gastropathy on microscopic and molecular levels. Wistar rats were pretreated intragastrically with vehicle, BW-HS-101 (0.5–50 μmol/kg) or its analogue without the ability to release H₂S, BW-iHS-101 prior to ASA administration (125 mg/kg, intragastrically). BW-HS-101 was administered alone or in combination with nitroarginine (L-NNA, 20 mg/kg, intraperitoneally) or zinc protoporphyrin IX (10 mg/kg, intraperitoneally). Gastroprotective effects of BW-HS-101 were additionally evaluated against necrotic damage induced by intragastrical administration of 75% ethanol. Gastric mucosal damage was assessed microscopically, and gastric blood flow was determined by laser flowmetry. Gastric mucosal DNA oxidation and PGE₂ concentration were assessed by ELISA. Serum and/or gastric protein concentrations of IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, IL-13, VEGF, GM-CSF, IFN-γ, TNF-α, and EGF were determined by a microbeads/fluorescent-based multiplex assay. Changes in gastric mucosal iNOS, HMOX-1, SOCS3, IL1-R1, IL1-R2, TNF-R2, COX-1, and COX-2 mRNA were assessed by real-time PCR. BW-HS-101 or BW-iHS-101 applied at a dose of 50 μmol/kg protected gastric mucosa against ASA-induced gastric damage and prevented a decrease in the gastric blood flow level. H₂S prodrug decreased DNA oxidation, systemic and gastric mucosal inflammation with accompanied upregulation of SOCS3, and EGF and HMOX-1 expression. Pharmacological inhibition of nitric oxide (NO) synthase but not carbon monoxide (CO)/heme oxygenase (HMOX) activity by L-NNA or ZnPP, respectively, reversed the gastroprotective effect of BW-HS-101. BW-HS-101 also protected against ethanol-induced gastric injury formation. We conclude that BW-HS-101, due to its ability to release H₂S in a controllable manner, prevents gastric mucosa against drugs-induced gastropathy, inflammation and DNA oxidation, and upregulate gastric microcirculation. Gastroprotective effects of this H₂S prodrug involves endogenous NO but not CO activity and could be mediated by cytoprotective and anti-inflammatory SOCS3 and EGF pathways.     

Evaluation Of Ozone/Biological Treatment For Disinfection Byproducts Control And Biologically Stable Water

Impacts of ozonation followed by biological filtration on the formation of disinfection byproducts and the production of biologically stable water were studied on pilot plant and full-scale at two U.S. locations (Oakland, CA and Tampa, FL). Also evaluated is a method to estimate bacterial regrowth potential by comparing it to assimilable organic carbon (AOC) measurements. At both locations, settled plant water is diverted to the pilot plant where it is split into two parallel trains. One train is ozonated, then Filtered through anthracite/sand dual media followed by GAC or through a GAC/sand dual media filter. The other train (control) is identical except that the water is not ozonated. The full scale plants have sedimentation, ozonation, then GAC/sand filtration.     

Application of space periodic variation of light polarization in imaging polarimetry

The application of space periodic variation of light polarization for measurement and calculation of the distribution of the phase retardation between two eigenwaves propagating inside a linearly birefringent media and the distribution of the azimuth angle of the first eigenvector is described. The measuring method proposed does not require any mechanical movements or rotations of any optical elements. Application of a liquid crystal (LC) modulator instead of a quarter-wave plate gives an opportunity to introduce the required phase shift. The space periodic modulation of the polarization of light is achieved by the use of a Wollaston prism placed inside the path of the light beam. Then a fast Fourier transform is used for further calculations. The number of measurements of the light intensity at the output of the system is minimized to two. These assumptions make the proposed method very fast, which is especially important in measurements of the objects with optical anisotropy that is changing in time.     

The effect of organic loading on process performance and membrane fouling in a submerged membrane bioreactor treating municipal wastewater

The results of experiments on municipal wastewater primary effluent are presented for a pilot-scale submerged membrane bioreactor (SMBR). The SMBR pilot plant employed an ultrafiltration membrane with a nominal pore size of 0.035 microm and was operated at a constant membrane flux of 30 L/m(2)h. The mixed liquor suspended solids (MLSS) concentration was maintained at 8+/-2 g/L and steady-state fouling rates were determined for 10, 5, 4, 3, and 2-d MCRTs, corresponding to food-to-microorganism (F/M) ratios of 0.34, 0.55, 0.73, 0.84, and 1.41 gCOD/gVSS d, respectively. Membrane fouling rates increased as the F/M was increased. Steady-state membrane fouling rates were correlated with total soluble microbial products (SMP) concentrations. The membrane fouling rates did not correlate well with soluble COD measured on a 0.45 microm membrane filtrate of mixed liquor or with soluble COD rejection (effluent COD/soluble COD).     

Numerical determination and experimental verification of the optimum autofrettage pressure for a complex aluminium high‐pressure valve to foster crack closure

The determination of the optimum autofrettage pressure enables a clear improvement of the fatigue life for an internally highly pressurized component. The autofrettage process induces residual compressive stress after the release of a single static overload pressure, leading to plastic deformation at the inner wall whereas the outer part is only elastically stressed. This autofrettage pressure is clearly above the subsequent pulsating operating pressure range. Due to the complex geometry of the aluminium valve body, a detailed elastic–plastic finite element analysis is used to determine the critical area and the optimum autofrettage pressure. Based on an experimental stress–strain curve, three important load steps are simulated in a non‐linear way. The FKM guideline is used to assess fatigue life and crack initiation with detailed subsequent experimental verification. Even if small cracks occur, residual compressive stresses prohibit crack growth (nonpropagating crack), which can be analytically verified by fracture mechanical considerations (crack closure effect).     

Formation and stabilization of combustion-generated environmentally persistent free radicals on an Fe(III)2O3/silica surface

Previous studies have shown environmentally persistent free radicals (EPFRs) form when chlorine- and hydroxy-substituted benzenes chemisorb on Cu(II)O-containing surfaces under postcombustion conditions. This paper reports the formation of EPFRs on silica particles containing 5% Fe(III)(2)O(3). The EPFRs are formed by the chemisorption of substituted aromatic molecular adsorbates on the metal cation center followed by electron transfer from the adsorbate to the metal ion at temperatures from 150 to 400 °C. Depending on the nature of the adsorbate and the temperature, two organic EPFRs were formed: a phenoxyl-type radical, which has a lower g-value of 2.0024-2.0040, and a second semiquinone-type radical, with a g-value of 2.0050-2.0065. Yields of EPFRs were ～10× lower for iron than copper; however, the half-lives of EPFRs on iron ranged from 24 to 111 h, compared to the half-lives on copper of 27 to 74 min. The higher oxidation potential of Fe(III)(2)O(3) is believed to result in greater decomposition of the adsorbate, resulting in the lower EPFR yields, but increased stabilization of the EPFR once formed, resulting in the longer half-lives.     

Infiltration of highly aligned carbon nanotube arrays with molten polystyrene

Highly aligned carbon nanotube/polystyrene (HACNT/PS) composites were prepared conveniently via polymer impregnation of aligned arrays, avoiding conventional solution or melt processes that involve high-shear blending. Detailed scanning electron microscopy (SEM), X-Ray diffraction (XRD) and differential scanning calorimetry (DSC) studies show that the alignment of the multi-wall nanotubes is retained after polymer impregnation. A range of key parameters were investigated, including the amount of molten polymer required for complete infiltration, the maximum mass fraction of CNTs in dense composites, and the effect of CNTs on the glass transition temperature (T_g) of the polymer. This approach may be adapted to the fabrication of large scale, highly anisotropic, thin or multilayer CNT composites using other molten polymers.