Conducting polymers with fibrillar morphology synthesized in a biphasic ionic liquid/water system

The synthesis of poly(pyrrole), poly(terthiophene), and poly(3,4-ethylenedioxythiophene) with unusual fibrillar morphologies has been achieved by chemical polymerization in a biphasic ionic liquid/water system. Use of aqueous gold chloride as the oxidant, with the monomers dissolved in a hydrophobic ionic liquid, allows the polymerization to occur at the ionic liquid/water interface. The resultant conducting polymer fibrils are, on average, 50−100 nm wide and can be thousands of nanometers long. The polymers produced in this ionic liquid system are compared to those synthesized in a biphasic chloroform/water system.

Microbial lipases : at the interface of aqueous and non-aqueous media: a review

In recent times, biotechnological applications of microbial lipases in synthesis of many organic molecules have rapidly increased in non-aqueous media. Microbial lipases are the working horses' in biocatalysis and have been extensively studied when their exceptionally high stability in non-aqueous media has been discovered. Stability of lipases in organic solvents makes them commercially feasibile in the enzymatic esterification reactions. Their stability is affected by temperature, reaction medium, water concentration and by the biocatalyst's preparation. An optimization process for ester synthesis from pilot scale to industrial scale in the reaction medium is discussed. The water released during the esterification process can be controlled over a wide range and has a profound effect on the activity of the lipases. Approaches to lipase catalysis like protein engineering, directed evolution and metagenome approach were studied. This review reports the recent development in the field of non-aqueous microbial lipase catalysis and factors controlling the esterification/transesterification processes in organic media.

Non-covalent surface modification of boron nitride nanotubes for enhanced catalysis

Boron nitride nanotubes were functionalized with microperoxidase-11 in aqueous media, showing improved catalytic performance due to a strong electron coupling between the active centre of microperoxidase-11 and boron nitride nanotubes.

Systematic approach to the quantitative voltammetric analysis of the Fe III /Fe II component of the [α 2 -Fe(OH 2 )P 2 W 17 O 61 ] 7-/8- reduction process in buffered and unbuffered aqueous media

The one-electron reduction of [α2-FeIII(OH2)P2W17O61]7- at a glassy carbon electrode was investigated using cyclic and rotating-disk-electrode voltammetry in buffered and unbuffered aqueous solutions over the pH range 3.45−7.50 with an ionic strength of approximately 0.6 M maintained. The behavior is well-described by a square-scheme mechanism P + e- ↔ Q (E10/ = −0.275 V, k10/ = 0.008 cm s-1, and α1 = 1/2), PH+ + e- ↔ QH+ (E20/ = −0.036 V, k20/ = 0.014 cm s-1, and α2 = 1/2), PH+ ↔ P + H+ (KP = 3.02 × 10-6 M), and QH+ ↔ Q + H+ (KQ = 2.35 × 10-10 M), where P, Q, PH+, and QH+ correspond to [α2-FeIII(OH)P2W17O61]8-, [α2-FeII(OH)P2W17O61]9-, [α2-FeIII(OH2)P2W17O61]7-, and [α2-FeII(OH2)P2W17O61]8-, respectively; E10‘ and E20‘ are the formal potentials, k10‘ and k20‘ are the formal (standard) rate constants, and KP and KQ are the acid dissociation constants for the relevant reactions. The analysis for the buffered media is based on the approach of Laviron who demonstrated that a square scheme with fully reversible protonations, reversible or quasi reversible electron transfers with the assumption that α1 = α2, can be well-described by the behavior of a simple redox couple, ox + e- ↔ red, whose formal potential, Eapp0‘, and standard rate constant, kapp0‘, are straightforwardly derived functions of pH, as are the values of E10‘, k10‘, E20‘, k20‘, and KP (only three of the four thermodynamic parameters in a square scheme can be specified). It was assumed that αapp = 1/2, and the simulation program DigiSim was used to determine the values of Eapp0‘ and kapp0‘, which are required to describe the cyclic voltammograms obtained in buffered media in the pH range from 3.45 to 7.52 (buffer-related reactions which effect general acid−base catalysis are included in the simulations). DigiSim simulations of cyclic voltammograms obtained in unbuffered media yielded the values of E10‘ and k10‘; KQ was then directly computed from thermodynamic constraints. These simulations included additional reactions between the redox species and H2O. The value of the diffusion coefficient of the [α2-FeIII(OH2)P2W17O61]7-, 2.92 × 10-6 cm2 s-1, was determined using DigiSim simulations of voltammograms at a rotating disk electrode in buffered and unbuffered media at pH 3.45. The diffusion coefficients of all redox species were assumed to be identical. When the pH is greater than 6, instability of P (i.e., [α2-FeIII(OH)P2W17O61]8-) led to the loss of the reactant and precluded lengthy experimentation.

Chemically induced phosphorescence from manganese(II) during the oxidation of various compounds by manganese(III), (IV) break and (VII) in acidic aqueous solutions

Chemiluminescence was observed during the manganese(III), (IV) and (VII) oxidations of sodium tetrahydroborate, sodium dithionite, sodium sulfite and hydrazine sulfate in acidic aqueous solution. From the corrected chemiluminescence spectra, the wavelengths of maximum emission were 689±5 and 734±5 nm when the reactions were performed in sodium hexametaphosphate and sodium dihydrogenorthophosphate/ orthophosphoric acid environments, respectively. The corrected phosphorescence spectrum of manganese(II) sulfate in a solution of sodium hexametaphosphate at 77 K exhibited two peaks with maxima at 688 and 730 nm. The chemical and spectroscopic evidence presented strongly supported the postulation that the emission was an example of solution-phase chemically induced phosphorescence of manganese(II) thereby, confirming earlier predictions that the chemiluminescence from acidic potassium permanganate reactions originated from an excited manganese(II) species.

Photocatalytic degradation of dye effluent by titanium dioxide pillar pellets in aqueous solution

Photocatalytic oxidation (PCO) process is an effective way to deal with organic pollutants in wastewater which could be difficult to be degraded by conventional biological treatment methods. Normally the TiO2 powder in nanometre size range was directly used as photocatalyst for dye degradation in wastewater. However the titanium dioxide powder was arduous to be recovered from the solution after treatment. In this application, a new form of TiO2 (i.e. pillar pellets ranging from 2.5 to 5.3 mm long and with a diameter of 3.7 mm) was used and investigated for photocatalytic degradation of textile dye effluent. A test system was built with a flat plate reactor (FPR) and UV light source (blacklight and solar simulator as light source respectively) for investigating the effectiveness of the new form of TiO2. It was found that the photocatalytic process under this configuration could efficiently remove colours from textile dyeing effluent. Comparing with the TiO2 powder, the pellet was very easy to recovered from the treated solution and can be reused in multiple times without the significant change on the photocatalytic property. The results also showed that to achieve the same photocatalytic performance, the FPR area by pellets was about 91% smaller than required by TiO2 powder. At least TiO2 pellet could be used as an alternative form of photocatalyst in applications for textile effluent treatment process, also other wastewater treatment processes.

Near-ultraviolet chemiluminescence from the reaction of ammonia with hypobromite in aqueous solution

The chemiluminescence arising from the oxidation of ammonium chloride by sodium hypobromite in aqueous alkaline solution includes a series of peaks in the near-ultraviolet, which is not commonly observed in liquid-phase chemiluminescence. The dominant peak in that region has an intensity maximum at 292 nm and smaller peaks are observed at 313, 334 and 356 nm. The emitted photons are of similar energy to the Vergard–Kaplan transition of molecular nitrogen, a major product of this reaction. However, the spectral distribution is different to that of previously reported gas-phase chemiluminescence attributed to the Vergard–Kaplan transition.

Investigation into the temporal stability of aqueous standard solutions of psilocin and psilocybin using high performance liquid chromatography

This paper reports an investigation into the temporal stability of aqueous solutions of psilocin and psilocybin reference drug standards over a period of fourteen days. This study was performed using high performance liquid chromatography utilising a (955% vlv) methanol: 10 mM ammonium formate,
pH 3.5 mobile phase and absorption detection at 269 nm. It was found that the exclusion of light significantly prolonged the useful life of standards, with aqueous solutions of both psilocin and psilocybin being stable over a period of seven days.

Polypyrrole-coated electrospun nanofibre membranes for recovery of Au(III) from aqueous solution

In this paper, for the first time, polypyrrole-coated electrospun nanofibre mats have been used as separation membranes to electrolessly recover Au from aqueous [Au(III)Cl₄]− solutions, based on a continuous-flow membrane separation process. With a [Au(III)Cl₄]− solution passing through the nanofibre membrane, the Au(III) ions were converted into elemental Au. The gold recovered was deposited on the nanofibre membranes in the form of Au particles, as confirmed by EDX and XPS measurements. It has been found that the polypyrrole-coated electrospun nanofibres are good candidate membrane material for the recovery of Au, and the recovery efficiency is affected by the membrane thickness, the permeate flux rate and the initial [Au(III)Cl₄]− concentration.

Dietary omega 3 fatty acids decrease intraocular pressure with age by increasing Aqueous outflow

Purpose: To determine whether there is an association between dietary omega-3 (ω-3) fatty acid intake, age, and intraocular pressure (IOP) caused by altered aqueous outflow. Methods: Sprague–Dawley rats were fed either ω-3–sufficient (ω-3⁺) or ω-3–deficient (ω-3^–) diets from conception. The diets had 7% lipid content. The ω-3⁺ diet contained safflower, flaxseed, and tuna oils (5.5:1.0:0.5), and the ω-3^– diet contained safflower oil only. Intraocular pressure was measured at 5 to 40 weeks of age under light anesthesia (ω-3⁺, n = 39; ω-3^–, n = 48). Aqueous outflow was determined at 45 weeks in a subgroup of animals (ω-3⁺, n = 15;ω-3^–, n = 22) using pulsed infusion. Ciliary body tissues (n = 6 per group) were assayed for fatty acid content by thin-layer and gas-liquid chromatography in both diet groups. Results: Animals raised on ω-3⁺ diets had a 13% decrease in IOP at 40 weeks of age (13.48 ± 0.32 mm Hg vs. 15.46 ± 0.29 mm Hg; P < 0.01). When considered as a change in IOP relative to 5 weeks of age, the ω-3⁺ group showed a 23% decrease (P < 0.001). This lower IOP in the ω-3⁺ diet group was associated with a significant increase (+56%; P < 0.001) in outflow facility and a decrease in ocular rigidity (–59%; P < 0.001). The ω-3⁺ group showed a 3.3 times increase in ciliary body docosahexaenoic acid (P < 0.001). Conclusions: Increasing dietary ω-3 reduces IOP with age because of increased outflow facility, likely resulting from an increase in docosanoids. This indicates that dietary manipulation may provide a modifiable factor for IOP regulation. However, further studies are needed to consider whether this can modify the risk for glaucoma and can play a role in treatment of the disease.

Anion recognition and sensing in organic and aqueous media using luminescent and colorimetric sensors

This review article focuses primarily on the work carried in our laboratories over the last few years using luminescent and colorimetric sensors, where the anion recognition occurs through hydrogen bonding in organic or aqueous solvents. This review begins with the story of the discovery of fluorescent photoinduced electron transfer (PET) sensors for anions using charged neutral urea or thiourea receptors where both fluorescent and NMR spectroscopic methods monitored anion recognition. This work led to the development of dual luminescent and colorimetric anion sensors based on the use of the ICT based naphthalimide chromophore, where ions such as fluoride gave rise to changes in both the fluorescence and the absorption spectra of the sensors, but at different concentrations. Here, the former changes were due to hydrogen bonding interactions, whereas the latter was due to the deprotonation of acidic protons, giving rise to the formation of the bifluoride anion (HF2−). Modification of the 4-amino-l,8-naphthalimide moiety has facilitated the formation of colorimetric anion sensors that work both in organic or aqueous solutions. Such charge neutral receptor motifs have also been incorporated into organic scaffolds with norbomyl and calixarene backbones, which have enabled us to produce anion directed self-assembled structures.

Photo-catalysis of red wine stains using titanium dioxide sol-gel coatings on wool fabrics

This paper investigated the use of titanium dioxide sol-gel coatings to photo-catalyse red wine stains on wool fabrics. Coatings were produced by the hydrolysis and condensation of titanium butoxide (Ti(OC4H9)4) on the surface of wool fabrics after pad application. Coatings were partially converted to the anatase form of titanium dioxide by prolonged immersion in boiling water. The coating presence was confirmed using scanning electron microscopy, UVspectrophotometry and atomic force microscopy. Coated samples were measured for photo-catalytic activity by degrading red wine stains from the surface of the coated fabric. The level of photocatalysis was determined for each of the coating systems after 168 hours. Red wine stains were photo-catalysed and level of staining was reduced from the UV exposed surface of the coated wool fabric.

Stimulation of cytokine production in human peripheral blood mononuclear cells by an aqueous Chlorella extract

CPE is an aqueous extract of the edible micro alga Chlorella pyrenoidosa, which has been shown to have immunostimulatory effects in vivo. In the present study, CPE was evaluated for an ability to stimulate cytokine production by human peripheral blood mononuclear cells (PBMC). PBMC from healthy individuals were treated ex vivo for 24 hours with 1, 10 and 100 μg/mL CPE. This resulted in a marked increase in the level of IL-10, a regulatory cytokine, and strong stimulation of the T-helper-1 (Th1) cell cytokines, IFN-γ and TNF-α. In contrast, stimulation of representative T-helper-2 (Th2) cell cytokines, IL-4 and IL-13, was minor. CPE (1, 10 or 100 μg/mL) did not cause a proliferation of human PBMC suggesting that enhanced secretion of cytokines was not secondary to an increase in cell number. We conclude that CPE stimulation of human PBMC induces a Th1-patterned cytokine response and a strong anti-inflammatory regulatory cytokine response, observations that await confirmation in vivo.

Aqueous/micellar peroxyoxalate chemiluminescent detection for ion chromatography

This thesis covers the development of the traditionally fluorescent bis(8-quinolinol-5-sulfonic acid) magnesium (II) fluorophore as a chemiluminescent emitter. A brief description of luminescence spectroscopy and its application to analytical chemistry lays the foundation to the discussion of the results obtained herein. This includes the synthesis and identification of two so called ‘water soluble’ aryl oxamides 2,2’-oxalyl-bis(trifluoromethanesulfonyl) imino] ethylene-bis(N- methylpyridinium) trifluoromethane sulfonate (PETQ) and 2,2’-oxalyl-bis(trifluoromethanesulfonyl) imino]ethylene-bis(N-pyridinium) chloride (PETH), previously developed for the US navy as a possible emergency light source, yet the synthetic methodology were incomplete. The inconsistencies of the synthetic methods for PETQ and PETH were overcome with yields satisfactory for their preliminary analytical evaluation. The evaluation of these aryl oxamides, including 4,4’-oxalyI- bis[(trifluoromethanesulfonyl) imino]ethylene-bis(l-methyM-benzylpiperidinium) trifluoromethanesulfonate (BPTQ), 4,4’-oxalyl-bis [(trifluoromethylsulfonyl)imino] ethylene-bis(N-methylmorpholinium)trifluoromethanesulfonate (METQ) and the oxalate bis(2,4,6-trichlorophenyl) oxalate (TCPO) were performed with the peroxyoxalate chemiluminescent reaction using bis(8-quinolinol-5-sulfonic acid) magnesium (II) as the fluorophore. A univariate optimisation of this system resulted in 0,0082 mol 1-1 the detection limit of magnesium in the absence of cationic surfactants and 0.0041 mol 1-1 in their presence for the majority of these compounds. The oxamides were found to be insoluble in water with long ulrasonication periods required to dissolve the compound, with solvents such as acetonitrile preferred. The determination of other chemiluminescent metal-8HQS chelates to replace magnesium -8HQS in the peroxyoxalate were limited to Al (III), Cd (II), Ca (II), In (II) and Zn (II), unfortunately these metals all possessed poorer detection limits than those obtained using magnesium The base reaction conditions used for the flow injection system with chemiluminescent detection were transferred to an ion chromatographic configuration for the separation of magnesium from other cations on an exchange column. After a univariate and simplex optimisation of these conditions, the detection limit of magnesium was found to be 0.0411 mol 1-1 which was less than the limits that could be achieved with fluorescent detection, The further development of this reaction to incorporate the displacement of magnesium from Mg-EDTA by other metals that possessed a higher conditional stability constant than magnesium also proved to be problematic with interferences from not only EDTA but from the eluant (lactic acid) from the cation column. Using this system the detection limits of the displacing metals were found to be in the order of 10 mg 1-1 which was substantially less that what was observed when exactly the same configuration was used with fluorescent detection. The final component of the thesis entails the discussion of the background emission that results from the reaction of oxamides/oxalates with hydrogen peroxide. A detailed investigation into the reaction of TCPO and hydrogen peroxide in the presence of various additives, such as imidazole , heavy atoms and triethylamine illustrated the existence of a further intermediate in fee mechanism for this reaction. The species responsible for this emission was attributed to the degradation product 2,4,6-trichlorophenyi of TCPO, which was supported by the non-existent background present with the oxamides that do not contain this degradation product.