Novel co-extruded electrolyte–anode hollow fibres for solid oxide fuel cells

Novel CGO/NiO–CGO dual-layer hollow fibres (HFs) have been fabricated in a single-step co-extrusion and co-sintering process. LSCF–CGO cathodes layers were then deposited onto the dual-layer HFs to construct micro-tubular SOFCs. The NiO in the micro-tubular HF–SOFCs was reduced at 550 °C using hydrogen gas to form Ni anodes. Scanning electron microscope images showed that the dual-layer HFs have porous anodes and dense electrolyte layers. Preliminary measurements with a HF–SOFC fed with H₂ and atmospheric oxygen, produced maximum power densities of 420 W m⁻² and 800 W m⁻² at 450 °C and 550 °C, respectively.     

Novel lipid system forming hollow microtubes at high yields and concentration

There is considerable interest in constructing supramolecular hollow tube architectures based on amphiphilic molecules. This can be achieved by using relatively expensive synthetic lipids. Herein, we report on the facile preparation of self-assembled microtubes from a novel low-cost lipid mixture that does not require a previous chemical synthesis step and consists of the ethanolamine salt of 12-hydroxy-stearic acid in water. Tubes of more than 10 microm in length spontaneously form upon cooling from an isotropic solution. They exhibit inner and outer diameters of 400 and 600 nm, respectively, and their walls consist of concentric stacked bilayers of fatty acid salts, each separated by a layer of water.     

Novel oxygen sensitive complexes for optical oxygen sensing

Novel optical sensing films for oxygen based on highly luminescent iridium (III) and ruthenium (II) complexes have been developed. These demonstrate excellent long-term photostability (several months) when incorporated into polystyrene membranes. The influence of different plasticizers on the specific luminescence quantum yield, the Stern-Volmer constant, the reversibility and the response time were evaluated. Additionally the sensing films can be sterilized by chemical cleaning and gamma-ray irradiation.     

Washing frozen red blood cell concentrates using hollow fibres

Today the cryopreservation of human blood products is routine. However, before reinfusion the cryoprotectant, often glycerol, has to be removed. We have designed a combined microfiltration diafiltration process using microporous hollow fibres for removing glycerol from frozen red blood cell concentrates. As the system can be closed to the atmosphere there is no possibility of infection of the “washed” blood. Thus the post-thaw shelf life of the blood may be greatly increased. The process has been optimized by minimizing both the processing time and diluent volume required. Finally a hollow fibre module capable of completing the entire washing process in 30 min has been developed. We show that such a module requires hollow fibres with an inside diameter of 200 μm. The design equations we present are generally applicable to the design of hollow fibre microfiltration systems.     

Phase transition temperature of water restrained in polysulfone hollow fibres

The melting and crystallization behaviour of water restrained in polysulfone (PSF) hollow fibre has been investigated by DSC. The PSF hollow fibre was prepared by wet spinning. The morphology of the fibre was observed by scanning electron microscopy. The amount of water was varied by successive evaporation and it was observed that melting and crystallization shifted to temperatures lower than those observed for free water. DSC and NMR studies showed that water in hollow fibres is in a restricted state.     

Heat transfer through a textile layer composed of hollow fibres

Textiles are used as thermal isolating materials for technical and clothing applications. The paper generally deals with heat transfer through textile layers by conduction, convection, radiation and evaporation of humidity. This experiment evaluates heat transfer by conduction and radiation through textile layers containing hollow polyethylene terephthalate (PET) fibres. The environment created by a composite textile layer containing hollow PET fibres and air is not identical for every method of heat transfer. During heat transfer through a textile layer, we evaluate of the importance of macromorphological structure of the elementary fibres and textile layer, taking into account the thermo-physiological properties.     

Engineering heterointerfaces coupled with oxygen vacancies in lanthanum-based hollow microspheres for synergistically enhanced oxygen electrocatalysis

The development of high-efficiency and low-cost bifunctional oxygen electrocatalysts is critical to enlarge application of zinc-air batteries(ZABs).However,it s...     

How slug flow can improve ultrafiltration flux in organic hollow fibres

The study deals with the use of a gas-liquid two-phase flow to reduce particle membrane fouling in organic hollow fibres by injecting air directly into the feed stream. A theoretical approach of slug flow in fibres demonstrates that the slugs created inside the fibres induce high wall shear stresses. Moreover, the membrane surface is alternately submitted to positive and negative shear stresses. This succession of stresses is expected to prevent filtered particles from settling on the membrane surface and then enhance the ultrafiltration mass transfer. Experiments were carried out with clay suspensions in hollow fibre membrane. A range of various air velocities and particle concentrations was examined and the effect of a steady gas flow was compared to that of an intermittent one. As expected, the injecting air process leads to an increase of the permeate flux by up to 110% for U_g=1 m s⁻¹ (flux multiplied by 2.1), for all the various concentrations studied. Furthermore, even at a low air velocity a significant enhancement can be achieved (+60% for U_g=0.1 m s⁻¹, flux multiplied by 1.6). An intermittent gas flow seems to be less effective than a steady one in similar experimental conditions.     

Micro-Winkler titration method for dissolved oxygen concentration measurement

In this report a gravimetric micro-Winkler titration method for determination of dissolved oxygen concentration in water is presented. Mathematical model of the method taking into account all influence factors is derived and an uncertainty analysis is carried out to determine the uncertainty contributions of all influence factors. The method is highly accurate: the relative expanded uncertainties (k = 2) are around 1% in the case of small (9-10 g) water samples. The uncertainty analysis carried out in characterizing the uncertainty of the method is the most comprehensive published for a micro-Winkler method, resulting in experimentally obtained estimates for all uncertainty sources of practical significance (around 20 uncertainty sources altogether).     

Novel adsorbent based on silkworm chrysalides for removal of heavy metals from wastewaters

In this contribution, maximum capacity for adsorption of Pb(2+), Ni(2+), and Cu(2+) by silkworm chrysalides (SC) was determined. The raw silkworm chrysalides (SC(r)) and chrysalides after acidic washing (SC(w)) were used. Chitin (CT), extracted from SC, and chitosan (CS), with 85% deacetylation, were employed as reference samples. Adsorption tests showed that all the studied adsorbents exhibited excellent performance in removal of metals. The choice of a more appropriate adsorbent is related to its efficiency for removal of a specific metal. The studied materials presented different intensities for metal adsorption as follows: (i) Ni(2+)>Cu(2+)>Pb(2+) for SC(r); (ii) Pb(2+)>Cu(2+)>Ni(2+) for SC(w); (iii) Ni(2+)>Cu(2+)>Pb(2+) for CT; and (iv) Cu(2+)>Pb(2+)>Ni(2+) for CS. Metal adsorption onto SC(r) and CS was analyzed by Freundlich and Langmuir isotherm equations. Adsorption values for CS-Pb and SC(r)-Ni were provided by the Freundlich model, while the adsorption values for CS-Cu, CS-Ni, SC(r)-Pb, and SC(r)-Cu were provided by the Langmuir model. The studied adsorbents are suitable for use in treatment of wastewater. From the economic point of view, the use of SC(r) as an adsorbent of heavy metals (mainly Ni(2+)) on the large industrial scale would be more appropriate.     

Novel one-step route for synthesizing CdS/polystyrene nanocomposite hollow spheres

CdS/polystyrene nanocomposite hollow spheres with diameters between 240 and 500 nm were synthesized under ambient conditions by a novel microemulsion method in which the polymerization of styrene and the formation of CdS nanoparticles were initiated by gamma-irradiation. The product was characterized by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA), which show the walls of the hollow spheres are porous and composed of polystyrene containing homogeneously dispersed CdS nanoparticles. The quantum-confined effect of the CdS/polystyrene nanocomposite hollow spheres is confirmed by the ultraviolet-visible (UV-vis) and photoluminescent (PL) spectra. We propose that the walls of these nanocomposite hollow spheres originate from the simultaneous synthesis of polystyrene and CdS nanoparticles at the interface of microemulsion droplets. This novel method is expected to produce various inorganic/polymer nanocomposite hollow spheres with potential applications in the fields of materials science and biotechnology.     

Novel hollow fiber immobilization techniques for whole cells and advanced bioreactors

A novel microporous hollow fiber membrane-based immobilization technique for whole cells has been developed. Yeast cells (Saccharomyces cerevisiae) were grown on chopped hydrophobic microporous hollow fibers as well as on hydrophilic hollow fibers. This immobilization support was used to carry out fermentation in a tubular bioreactor. Air was passed from time to time to facilitate cell growth. The microbial culture reached a very high cell density level of around 10¹⁰/mL of fiber lumen volume. An ethanol concentration of 45 g/L and productivity of 41 g/L-h were obtained with an initial glucose concentration of 100 g/L. The present technique does not have the shortcomings of conventional immobilization methods.     

Novel graphene materials for the oxygen reduction reaction

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Pervaporation in hollow fibres: : Efficiency coefficient via the fractal concept

The complexity of the equations for the simultaneous transfer of momentum, heat and mass with a change in the physical state of a membrane means that only the use of an overall coefficient can account for the performance of an industrial hollow fibre pervaporator; this coefficient is expressed by means of the mathematical fractal concept.     

Novel hollow microcapsules based on iron-heparin complex multilayers

Iron-polysaccharide complex have been extensively utilized in the treatment of iron deficiency anemia for parenteral administration. Herein, a novel iron-heparin complexed hollow capsules with nanoscaled wall thickness have been fabricated by means of alternating deposition of ferric ions (III) (Fe+) and heparin (Hep) onto the surface of submicroscaled (488 nm) and microscaled (10.55 microm) polystyrene latex particles via both electrostatic interaction and chemical complexation processes, followed by dissolution of the cores using tetrahydrofuran. Confocal micrographs and atomic force microscopy (AFM) images prove that iron-heparin complexed submicroscaled hollow capsules keep spherical shapes in solution and even after drying. The activated partial thromboplastin time (APTT) assay shows that complexing with ferric ions do not compromise the catalytic capacity of heparin to promote antithrombin III-mediated thrombin inactivation. The anticoagulant activity value of (Fe3+/Hep)8 capsules is evaluated to be about 95.7 U/mg, indicating that approximately 0.55 mg heparin was in 1 mg powder of submicroscaled (Fe3+/Hep)8 hollow capsules. Compared with the same dosage of heparin, iron-heparin complexed hollow capsules display a more prolonged anticoagulant duration than heparin. All these results reveal that such submicroscaled iron-heparin complexed hollow capsules have application potential as an injectable anticoagulant vehicle.     

Novel and facile method for the preparation of monodispersed titania hollow spheres

The fabrication of monodispersed hollow spheres in varying sizes and shapes is very interesting and has a lot of potential applications. This paper provides a very simple route to preparing hollow titania spheres using polystyrene (PS) as a template. In this approach, the titania shells were first formed and the PS cores were dissolved subsequently, even synchronously, in the same medium; neither an additional dissolution nor a calcination process was needed to remove the PS cores. Transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and Barret-Emmet-Teller measurements were used to characterize the monodispersed hollow titania spheres. A possible formation mechanism of the hollow spheres was proposed.     

Manganese vanadium oxide hollow microspheres: a novel electrocatalyst for oxygen reduction reaction

Journal of Solid State Electrochemistry - The development of nonprecious catalysts with high electrocatalytic activities for the oxygen reduction reaction (ORR) has attracted considerable...     

Novel cobalt-free oxygen permeable membrane

A series of cobalt-free and low cost perovskite oxygen permeable membranes based on BaCe(x)Fe(1-x)O(3-delta)(BCF) oxides was successfully synthesized and the membrane showed both high oxygen permeability and high stability under reductive atmosphere, which will be most suitable for constructing a membrane reactor for selective oxidation of light hydrocarbons to syngas or high value corresponding oxygenates.     

Novel electrocatalysts for generating oxygen from alkaline water electrolysis

We have obtained spinel-type Co₃O₄ and La-doped Co₃O₄ in the form of thin film on Ni, using microwave-assisted synthesis, which dramatically exhibit very low overpotentials for the oxygen evolution reaction (OER). Investigations have shown that at the apparent current density of 100 mA cm⁻² in 1 mol dm⁻³ KOH at 25 °C, the new electrodes, Co₃O₄ (oxide loading = 3.4 ± 0.3 mg cm⁻²) and La-doped Co₃O₄ (oxide loading = 2.8 ± 0.4 mg cm⁻²), produce overpotentials, 235 ± 7 and 224 ± 8 mV, respectively. Such low overpotentials for the OER, to our knowledge, have not been found on any mixed oxide electrode material reported in literature till today. Small La addition improved the BET surface area and porosity of the oxide catalyst powder and reduced the charge transfer resistance for the OER on the electrode made of oxide powder.