Magnetically responsive polypyrrole nanotubes using Ce(III)-stabilized maghemite nanoparticles

Nanocomposites (NCs) that are made magnetically responsive in controlled conditions attract continuing interest for their added magnetic properties. In this study, we report on the preparation and full characterization of a multifunctional NC composed of magnetic γ-Fe(2)O(3) nanoparticles (NPs) covalently attached to the surface of polyaminated (polyNH(2)) poly(2,6-di-pyrrol-1-yl-hexanoic acid) (pDPL) nanotubes (NTs). Such a hybrid conducting polymer iron oxide maghemite γ-Fe(2)O(3)@pDPL NC built specifically on covalent bonding has never been reported. The maghemite γ-Fe(2)O(3) NPs were prepared using an innovative ultrasound-assisted Ce(3+) doping process, resulting in polycarboxylation of the NP surface useful for control of aggregation and derivatization of functionality. The second component of the NC, i.e. polyNH(2)-modified pDPL NTs, was prepared from an acid functional pyrrole species followed by amine modification. The resulting innovative γ-Fe(2)O(3)@pDPL NC can be viewed as a multifunctional nanomaterial since it possesses both types of derivatization, i.e. polyCOOH (NPs) and polyNH(2) (NTs) combined with magnetic responsivity.     

Occupational exposure to staff during endoscopic retrograde cholangiopancreatography in Sudan

Endoscopic retrograde cholangiopancreatography (ERCP) procedure is an invasive technique that requires fluoroscopic and radiographic exposure. The purpose of this study was to determine the occupational dose of ionising radiation at three gastroenterology departments (Fedial, Soba and Ibn seena hospitals) in Khartoum, Sudan. The radiation dose was measured during 55 therapeutic ERCP procedures. Thermoluminescence dosemeters were used. The mean radiation dose for the first operator was 0.27 mGy for the eye lens, 0.21 for the thyroid, 0.32 for the chest, 0.17 for the hand and 0.22 for the leg. The mean radiation dose for the second operator was 0.21 mGy for the hand and 0.20 mGy for the chest, while the mean radiation dose for the nurse was 0.44 mGy for the hand and 0.19 for the chest. The radiation dose received by the staff in these hospitals was found to be higher than most of the values in the literature. The radiation absorbed dose received by the different organs is relatively low. Additional studies need to be conducted for radiation dose optimisation.     

Single nanoskived nanowires for electrochemical applications

In this work, we fabricate gold nanowires with well controlled critical dimensions using a recently demonstrated facile approach termed nanoskiving. Nanowires are fabricated with lengths of several hundreds of micrometers and are easily electrically contacted using overlay electrodes. Following fabrication, nanowire device performance is assessed using both electrical and electrochemical characterization techniques. We observe low electrical resistances with typical linear Ohmic responses from fully packaged nanowire devices. Steady-state cyclic voltammograms in ferrocenemonocarboxylic acid demonstrate scan rate independence up to 1000 mV s(-1). Electrochemical responses are excellently described by classical Butler-Volmer kinetics, displaying a fast, heterogeneous electron transfer kinetics, k(0) = 2.27 ± 0.02 cm s(-1), α = 0.4 ± 0.01. Direct reduction of hydrogen peroxide is observed at nanowires across the 110 pM to 1 mM concentration range, without the need for chemical modification, demonstrating the potential of these devices for electrochemical applications.     

Multifunctional nanoparticles, nanocages and degradable polymers as a potential novel generation of non-invasive molecular and cellular imaging systems

In recent years, polymeric scaffolds have been used in several biomedical applications for delivery of drugs or other biologically relevant molecules. Polymeric nanostructures display different (and in some cases more powerful) properties respect to bulk materials. This, lead academic researchers and industry to cooperate in developing pioneering nanostructured materials for industrial and biomedical applications. Moreover, the preparation and use of systems with multiple (multifunctional) properties (i.e., bioconjugation with superparamagnetic, fluorescent or targeting molecules) is positioned to become a viable and innovative tool for application in several clinical fields. Other nanostructured systems like nanocages and degradable nanoparticles, are emerging as potential innovative systems that could be exploited as multifunctional delivery vectors. This brief critical review is aimed at collecting and discussing some recent patents dealing with the preparation and use of multifunctional nanoparticles, nanocages and degradable nanoparticles in biomedicine and non-invasive bioimaging applications. Perspectives for a potential use of these multifunctional nanosystems in pediatries have been also discussed.     

Municipal solid waste compost application improves productivity, polyphenol content, and antioxidant capacity of Mesembryanthemum edule

Organic wastes were successfully used as soil amendment to improve agrosystems productivity. Yet, the effectiveness of this practice to enhance plant antioxidant capacities has received little attention. Here, we assess the effect of municipal solid waste (MSW) compost (at 40 t ha(-1)) on growth, polyphenol contents and antioxidant activities of Mesembryanthemum edule. MSW compost application significantly increased the soil contents of carbon, nitrogen, calcium, phosphorus and potassium. This was associated with higher nutrient (N, P, and K) uptake, which likely led to the significant improvement of the plant biomass and relative growth rate (RGR) (+93% on average) as compared to the control. In the same way, the fertilizing effect of the added organic matter significantly enhanced the antioxidant potential M. edule, assessed by radical scavenging activity, iron reducing power and β-carotene bleaching capacity. This was associated with significantly higher antioxidant contents, mainly total phenols and flavonoids. Heavy metal (Pb, Cd, Cu, and Zn) concentrations were slightly increased upon compost application, but remained lower than phytotoxic values. Overall, our results point out that short-term MSW compost application at 40 t ha(-1) is efficient in enhancing the productivity together with the antioxidant potentiality of M. edule without any adverse environmental impact.     

Sequencing Batch Reactor (SBR) for the removal of Hg2+ and Cd2+ from synthetic petrochemical factory wastewater

Petrochemical factories which manufacture vinyl chloride monomer and poly vinyl chloride (PVC) are among the largest industries which produce wastewater contains mercury and cadmium. The objective of this research is to evaluate the performance of a lab-scale Sequencing Batch Reactor (SBR) to treat a synthetic petrochemical wastewater containing mercury and cadmium. After acclimatization of the system which lasted 60 days, the SBR was introduced to mercury and cadmium in low concentrations which then was increased gradually to 9.03±0.02 mg/L Hg and 15.52±0.02 mg/L Cd until day 110. The SBR performance was assessed by measuring Chemical Oxygen Demand, Total and Volatile Suspended Solids as well as Sludge Volume Index. At maximum concentrations of the heavy metals, the SBR was able to remove 76-90% of Hg(2+) and 96-98% of Cd(2+). The COD removal efficiency and MLVSS (microorganism population) in the SBR was affected by mercury and cadmium concentrations in influent. Different species of microorganisms such as Rhodospirilium-like bacteria, Gomphonema-like algae, and sulfate reducing-like bacteria were identified in the system. While COD removal efficiency and MLVSS concentration declined during addition of heavy metals, the appreciable performance of SBR in removal of Hg(2+) and Cd(2+) implies that the removal in SBR was not only a biological process, but also by the biosorption process of the sludge.     

Grating-coupled surface plasmon enhanced short-circuit current in organic thin-film photovoltaic cells

In this study, we demonstrate the fabrication of grating-coupled surface plasmon resonance (SPR) enhanced organic thin-film photovoltaic cells and their improved photocurrent properties. The cell consists of a grating substrate/silver/P3HT:PCBM/PEDOT:PSS structure. Blu-ray disk recordable substrates are used as the diffraction grating substrates on which silver films are deposited by vacuum evaporation. P3HT:PCBM films are spin-coated on silver/grating substrates. Low conductivity PEDOT:PSS/PDADMAC layer-by-layer ultrathin films deposited on P3HT:PCBM films act as the hole transport layer, whereas high conductivity PEDOT:PSS films deposited by spin-coating act as the anode. SPR excitations are observed in the fabricated cells upon irradiation with white light. Up to a 2-fold increase in the short-circuit photocurrent is observed when the surface plasmon (SP) is excited on the silver gratings as compared to that without SP excitation. The finite-difference time-domain simulation indicates that the electric field in the P3HT:PCBM layer can be increased using the grating-coupled SP technique.     

Application of nanofiltration for chromium concentration in the tannery wastewater

The article presents results of investigation concerning an influence of tannery wastewater composition on chromium(III) concentration in the wastewaters during the nanofiltration process (NF). The effectiveness of this process strongly depends on mutual relation between chloride and sulfate ions concentration in tannery wastewater. For this reason, the optimum composition of the tannery wastewater should consist chloride/sulfate ions ratio close to 1. Moreover, an influence of transmembrane pressure (TMP) and the "ageing" of chromium tannery wastewater on the efficiency of the process has been investigated. Optimal range of TMP equal to 14-16 bar has been assumed for the process. It is necessary to point out that the optimum transmembrane pressure can be changed in the case of the membranes with different permeation properties. "Ageing" of the tannery wastewater reduces only a little an efficiency of the process. Experimental results demonstrated that the NF process could be successfully used for the concentration of chromium in the tannery wastewater with high permeate flux, selectivity and performance stability.     

Terrestrial gamma radioactivity levels and their corresponding extent exposure of environmental samples from Wadi El Assuity protective area, Assuit, Upper Egypt

Representative environmental samples (sandy soil, limestone, marble and gravels) collected from Wadi El Assuity, protective area, Assuit governorate in Upper Egypt have been investigated radiometrically using NaI (Tl) gamma-ray spectrometer. The specific activity of the radionuclides in Bq kg?1 for soil ranged between 10.5 and 18.7 for 22?Ra, 1.5 to 4.6 for 232Th and from 94 to 107 for ??K, for limestone ranged between 19 and 27.1 for 22?Ra, 32.9 to 50 for 232Th and from 49 to 7 3 for ??K, where, for marble ranged between 12.2 and 30.7 for 22?Ra, 32.6 to 59.5 for 232Th and 55 to 70 for ??K and for gravels ranged between 7.8 and 21.8 for 22?Ra, 19.8 to 30.0 for 232Th and from 151 to 260 for ??K. The mean activity concentrations of measured radionuclides were compared with other literature values. The absorbed dose rate, radium equivalent activity and external hazard index were calculated and compared with internationally recommended values. The gamma absorbed dose rates in the samples ranged between 8.44 and 50.89 nGy h?1. These dose rates are consistent with the accepted worldwide average 55 nGy h?1 for the public. All values obtained for radium equivalent activity are < 370 Bq kg?1, which are acceptable for safe use. The calculated values of external hazard index obtained varied from 0.12 to 0.24. Since these values are lower than unity, one can say that the radiation hazard is insignificant for the population living in the investigated area. This permits the use of these materials sediments as building materials in any probable development projects at this area.