provides new and improved methods for making chalcogenide compounds, including, but not limited to, non- protonated sulfide, selenide and telluridecompounds. In one embodiment, the proton conductivity of the compounds is between about 10 −8 S/cm and 10 −1 S/cm within a temperature range of between about −50 and 500° C.
and reduction . In thermal treatment, increasing temperature causes some substances to decompose into wastewater. Organic compounds decompose into carbon dioxide, water and halides, or halogen gases. Due to the fact that decomposition conditions are usually close to the critical point of water, all wastewater is exposed to phase change conditions, and thus in this case the treated water obtains liquidation of vapors or returns the conditions to the original state. . For this reason, thermal methods are often used to remove solid waste. Thermal treatment in the industry is usually carried out by wet-oxidation, super-critical oxidation and burning methods . In biological treatment of microorganisms, changes in the properties of the substances are given and it decomposes some of the compounds in the wastewater. Organic compounds in this case are a source of nutrients for microorganisms. The final product is microbial decomposition of cell masses, carbon dioxide, water, halides, nitrogen and sulfur. Often the decomposition of the compounds is not complete, and molecules with a low molecular weight such as alcohol, ketones and organic acids are formed. Biological processes in the industry include active sludge process, aeration or stabilization basins, fixed film reactors and anaerobic processes. Gravitational separation is the most common method for treating oily wastewater. If the outflow does not meet the constraints required, secondary treatment steps are used to reduce dissolved, emulsified, and dispersed oil. The emulsion is broken down by chemical materials, followed by a sedimentation system for the separation of excess oil . If the chemical breakdown method is used well, the method will be effective, but it will be difficult to handle in many cases. Among the drawbacks of this method are the following:
Fig. 5 shows that SBS and eSBS undergo complete degradation at 500 °C. The TGA curves show one step decrease in their mass, Fig. 5. In ionomer, there is over 20% residual mass due to the presence of ionic –SO3Na groups which form the tiny ionic aggregates attached to the organic mass, possibly responsible for the stability of the ionomer. Similarly, upon addition of 5 wt.-% nanofiller such as Nanofil-5 to the ionomer, the residual mass again increased. The reasons of these enhancements in residual masses are not well understood; and more experiments are required to clarify these issues. Laboratory Test of Ionomer Films as ProtonConducting Membrane
assigned to hydrogen bonded protons in the 1D spectra shown in figure 3.2a contributes to the diffusion as measured by NMR. This suggests there could be structural differences across the NSF resin which prevents certain protons from participating in diffusion. The diffusion rates measured between 20 °C and 100 °C show constant increase as the temperature rises. This is in con- trast to impedance spectroscopy of NSF where the measured impedance starts to decline when the temperature rises above 50 °C. This suggests that there is a macroscopic breakup of NSF which prevents longer distance proton mobility but at the small distances probed by NMR PFG proton mobility continues to increase. The attenuation of the signal in the PFG-STE experiment is linear and can there- fore be simulated with a single diffusion coefficient. The diffusion coefficients are shown in figure 3.8 which have been simulated using an Arrhenius model to estimate the thermal activation energy to proton diffusion which yielded a value of 31 ± 2 kJ mol − 1 .
thesized PEMs were characterized using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy for the identification of precursor mat- erial and inter polymer interactions, respectively. The water uptake and ion exchange capacity of the synthesized membranes were quantified to optimize the composition of the membrane. The synthesized membranes were used in a MFC and the performance of the same was monitored with respect to open circuit voltage (OCV), power and current density, and compared with the conventional Nafion 117 membrane. Chemical oxygen demand (COD) removal of wastewater was measured using the synthesized membranes in the MFCs.
solution . A novel Nafion /silica hybrid membrane suggested the –OH on the surface of silica nano particles could enhance the hydrophilicity of clusters inside the membranes and improve the proton conductivity at elevated temperatures . PVDF grafted polystyrene sulphonic acid proton exchange membranes based on a radiation grafting technique showed higher proton conductivity and higher water uptake ability compared to nafion membranes . In the present study PSEBS was sulphonated separately to make it protonconducting. It exhibited good conductivity, flexibility and chemical stability but its mechanical properties were not adequate for direct application in fuel cell. Hence it was blended with different proportions of PSEBS, characterized by XRD, FTIR, SEM, etc., and their results are discussed.
Solid acid salts, mainly based on tetrahedral oxyanion groups have received attention recently due to their unusual proton conductivity at anhydrous conditions. Unlike the water containing systems discussed above, proton conduction in oxyanion solid acid salts does not rely on the migration of hydronium ions. Consequently, the requirement for humidification and temperature control, in principle, can be eliminated. The enhanced operation temperatures furthermore imply a fast catalysis rate, opening up possibilities for reduction or even replacing precious metal catalysts. This advantage additionally implies a high tolerance of catalysts to poisons, particularly CO so that it may avoid using fuel purifying systems. The oxyanion solid acid salts can be written in formula MHXO 4 , M 3 H(XO 4 ) 2 , M 2 H(X’O 4 ) or some variation thereof, where M= alkali metal
PVA membranes containing carbon nanotubes (CNTs) have been reported, with β-cyclo-dextrin being used as a dispersant . They showed improved permeate flux and separation efficiency in OPV of benzene/cyclohexane mixtures, as well as better mechanical properties, compared with unfilled membranes. The work follows similar studies where graphite flakes or carbon molecular sieves were introduced into the membrane to give analogous improvements in both flux and selectivity . The results were attributed to a higher free volume and more relaxed polymer chain packing which could reduce the mass transfer resistance and facilitate permeation of benzene. However, excessive filling inhibited permeation.
The heterocyclic compounds, especially nitrogen-containing heterocycles with a sulfur atom are an important class of compounds in medicinal chemistry.[1-4] Hydrazinolysis of esters is the conventional method for preparing acyl hydrazides [5,6].However, when this method was applied to an α, β-unsaturated ester, the predominant product was the corresponding pyrazolidinone, the result of hydrazinolysis and an undesired subsequent intramolecular Michael- type addition . In current era, the research on hydrazides and its derivatives are carried out due to their heterocyclised products display diverse biological activities including antibacterial, antifungicidal, analgesic, anti- inflammatory properties [8-10]. Other heterocyclic compounds says, oxadiazoles and their condensed products play a vital role in medicinal chemistry and exhibit diverse biological activities such as antibacterial, antifungal, anti- inflammatory, analgesic and anticancer activity[11-15]. Hence, it was thought of interest to combine Sulfapyrimidine containing benzimidazole with oxadiazole moieties which may enhance the drug activity of compounds to some extent, or they might possess some of the above mentioned biological activities. Hence in continuation of our earlier work , the current communication covers the study of 4-((1-((4- ((dialkylamino)methyl)-5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)methyl)-1H-benzo[d]imidazol-2-yl)methyl amino)-N-(pyrimidin-2-yl)benzenesulfonamide (4a-e). The synthetic approach is shown in scheme-1.
The DS 68% SPEEK composite membranes were prepared by post-sulfonation. Using epoxy is as cross-linking agent to form SPEEK/epoxy interpenetrating network structures and explore half- interpenetrating networks on the impact of membrane performances. The sulfonated graphite oxide was grafted on the SPEEK backbones and optimized the formulation. Finally a series of SPEEK/epoxy proton exchange membranes were prepared. It is found that the graft sulfonated graphene oxide content in the membrane need to be high to achieve the sameproton conductivity. When the proton conductivity reaches a certain value and continue to increase the content of sulfonated graphene oxide, there will be a ‘blocking effect’ which due to the proton conductivity reduce instead. The cross-linked of epoxy resin has part of the effects on the proton conductivity of graft membrane. The highest value reached 5.2×10 -2 S·cm -1 . But it is still falling with the increase content of epoxy resin. Introduction of the sulfonic acid groups provide springboard for proton exchange membrane conduction protons. The part of epoxy crosslinking increased the density of proton exchange membrane. The water swelling resistance of the membrane has a good improvement. The structure will not be loose at high temperature, and guide protons performance is not affected. Alcohol by gas chromatography of the membrane resistance performance, found half interpenetrating network could effectively improve the proton exchange membrane resistance performance, with the increase of epoxy resin content in methanol permeability decreasing. When the epoxy resin content is above 15 wt. %, the decline is not obvious and the methanol permeability coefficient are less than 1.8×10 -8 S·cm -1 . Epoxy cross-linking components significantly reduce SPEEK skeleton absorb moisture capacity, effective the control of membrane structure and increase the interaction between the polymer and sulfonated graphene oxide. In additional, the sulfonated graphene oxide and epoxy resin increase the mechanical stability and alcohol resistance performance of membranes.
In this article, we report a simple test system that has been designed and manufactured to measure through-plane ionic conductivity of bare (non catalyzed) PEMs at different temperature and humidity conditions. The design builds on Cooper’ work, whereby the nanostrucured Pt catalyst layer is detached from the membrane and added to the gas diffusion electrode (GDE). Emphasis is placed on recycling the humidifying gas after exiting the test cell making it more cost effective than Cooper’s cell. To assess the manufactured cell’s applicability, we used it to determine the ionic conductivity of a model Nafion membrane at different temperatures. Electrochemical impedance spectroscopy (EIS) was applied using a frequency range of 10 -1 to 10 5 Hz. Nyquist plots were used to analyze the impedance spectra. Equivalent circuit modeling of the EIS data was used to extract the Ohmic membrane resistance which was in turn used to calculate the membrane ionic conductivity using self-developed fitting routines.
Having so far probed what might philosophically and theoretically underlie different approaches to making public space in different design instances across cities in different geographies and cultures around the globe, this text now turns to specific practice. Below is a comparative collage of eight actual cases of making public space in three categories of project—place, program and strategy, which together seek to establish whether design approaches tend towards similarity or difference across inherently different locations across the world. The projects represent three climatically and socio-culturally distinct circumstances and are drawn from this author’s portfolio and associated knowledge. The latter fact admittedly limits the scope of the discussion, but the range of project type and origin still allows for legitimate conclusions by author and, independently, by the reading audience for whom the questions are left open.
Because of their excellent proton conductivity and mechanical strength, sulfonic acid membranes of varying kind have been extensively studied as PEMs. Sulfonated aromatic polymers that have been employed include poly(etheretherketone) (PEEK) and poly(ether ketone) (PEK). Figure 4 shows the relative conductivity of a variety of materials in which the temperature dependence of proton conductivity has been studied. One can see that sulfonated polymers like Nafion ® , exhibit high proton conductivity, above 10 -1 Scm -1 , at temperature below 100˚C. The benzimidazole/H 3 PO 4 liquid membrane exhibits high proton conductivity at high
MPa for 5 min and then sintered at 250 °C for 8 hrs in air. For conductivity measurements, the pellet was painted with colloidal silver on both sides, and dried in an oven at 120°C for about 2 hrs until colloidal silver was solidified. A silver wire mesh connected to a silver wire was separately placed in contact with the painted pellet on both sides and was pressed against mica sheets to ensure proper electrical contact. The proton conductivity was measured with Autolab PGSTAT302. The impedance measurements were carried out between frequencies of 1 and 10 kHz. The perturbation voltage was kept at 10mV. The crystal structures of different powders were analysed using X-ray diffraction (XRD,X’Pert PROMPD), with a scan range of 5–70°. The morphologies of the SnP 2 O 7 membranes
Many Attempts to fill the pores of polymeric membranes with finely dispersed precipitates of inorganic proton conductors have been reported. Voids in porous inert polymer such as porous Teflon® can be filled with a solution of a metal (IV) alkoxide. Insoluble metal (IV) hydrous oxide is formed directly inside the membrane pores, by exposing this membrane to wet air. Protonic conductivity of these membranes can be enhanced by treatment with phosphoric acid, which converts the metal (IV) hydrous oxide into its acid phosphate. 7 Alternative treatments between a solution of a zirconyl chloride and phosphoric acid can be used to allow the direct precipitation of amorphous ZrP within the membrane pores 26 . Peled et al., 27 reported the fabrication of a nanoporous proton-conducting membrane that consists of a ceramic nanopowder (SiO 2 ), PVDF and an acid and its application in a direct methanol fuel cell. 28 Nevertheless, the conductivity of this type of membranes is extensively dependent on particle-particle paths connecting the external faces of the membrane. The conduction becomes satisfying only for high contents (>50% V/V) of added particles whereby the strength of the composite membrane becomes a problem. 7
The T. brucei parasite encounters diverse environments during its life cycle, and in the different hosts take on very different sterol compositions. Of particular interest is the variance in the ergosterol homoeostasis, which is poorly understood (Haubarich et al !"#$). Studies indicate that ergosterol is the major sterol of T. brucei procyclic cells (Dixon et al. -./0; Gros et al. 0556; Furlong -.:.). In mammalian hosts where cholesterol may be abundant (i.e. in humans), the ergosterol pathway is significantly downregulated in BSF and sterol requirements are met via receptor-mediated endocytosis of host cholesterol (Coppens et al. -.//). As a result, it has long been held that T. brucei’s ability to scavenge cholesterol from their animal hosts, and their inability to undergo sterol biosynthesis in this adaptive stage, makes them resistant to antiparasitic drugs that target ergosterol or ergosterol biosynthesis (Gros et al. ,--.; Hinshaw et al. -../). However, it has since been demonstrated that T. brucei BSF satisfy two different functions with the two sterols: exogenous cholesterol (from the host) functions as structural component in membranes, while there is endogenously formed ergosterol that functions as a signal molecule, essential to their growth and survival (Nes et al. '()', Roberts et al. '((0). Interestingly, one study showed that in cases in which cholesterol from the diet is minimal for BSF, the ergosterol pathway is upregulated (Zhou et al. ,--.). Alternatively, in cases in which cholesterol availability is significant, the endogenous pathway to ergosterol is downregulated but not eliminated.
It can be observed that the ionic conductivity at room temperature (27 o C) and room RH (68%) of the membranes increased with increasing SFA concentration up to 35 wt. %, after which the conductivity decreased (Table 1). The variation in polymer conductivity is due to ion association and dissociation . The decrease in conductivity at higher concentrations is probably caused by the formation of ion aggregates, which decrease the number of free mobile ions available to take part in the conduction process. The samples PF6 was then chosen for futher step (blend with TriA) due to the best compostion of PVDF-HFP/SFA ratio that has produced the highest conductivity.