Conjugated polymers for light-emitting applications

Processable conjugated polymers such as those shown in the Figure are highly desirable for applications in, for example, light emitting devices, especially electrochemical light-emitting cells. Here recent progress in Australia on the synthesis and device applications of such polymers is reviewed and the possibility of tuning the emitted color via an intercalation-induced conformational change of the polymer backbone is examined.

Use of ionic liquids for π-conjugated polymer electrochemical devices

π-Conjugated polymers that are electrochemically cycled in ionic liquids have enhanced lifetimes without failure (up to 1 million cycles) and fast cycle switching speeds (100 ms). We report results for electrochemical mechanical actuators, electrochromic windows, and numeric displays made from three types of π-conjugated polymers: polyaniline, polypyrrole, and polythiophene. Experiments were performed under ambient conditions, yet the polymers showed negligible loss in electroactivity. These performance advantages were obtained by using environmentally stable, room-temperature ionic liquids composed of 1-butyl-3-methyl imidazolium cations together with anions such as tetrafluoroborate or hexafluorophosphate.

Novel dithiolene complexes incorporating conjugated electroactive ligands

A series of new metal (M) dithiolene complexes bearing terthiophene (3, 12, M = Ni; 4, M = Pd; 5, 6, M = Au) and 2,5-bis(para-methoxyphenyl)thiophene units (14, M = Ni; 15, 16, M = Au; 17, M = Pd) have been synthesised in 38–99% yield. The electrochemical properties of the materials have been characterised by cyclic voltammetry and UV-vis spectroelectrochemistry. The nickel complexes possess low oxidation potentials (−0.12 to −0.25 V vs Ag/AgCl) due to the electron-rich dithiolene centres and all complexes display ligand-based redox activity. The terthiophene derivatives have been polymerised by electrochemical oxidation to give stable films with, in the case of poly(3), broad absorption characteristics. Charge transfer materials have been isolated from 14 and 16 with conductivities in the range 9 × 10⁻⁶ to 7 × 10⁻⁸ S cm⁻¹.

Soluble poly-3-alkylpyrrole polymers on films and fabrics

Conductive textiles with specific properties can be produced by the chemical polymerisation of a range of 3-alkylpyrroles in the presence of textiles. The morphologies of these coatings are altered from the traditional conductive coatings. Comparison using a SEM reveals substantial differences.

Application of soluble poly (3-alkylpyrrole) polymers on textiles

Soluble conducting poly(3-decanylpyrrole) was directly applied to textiles as a nanoparticle emulsion, using a variety of techniques including hand-brushing, dipping and spray painting. These coatings were compared to those formed by chemical polymerization of 3-decanylpyrrole on the surface of the textile by solution, using vapor and spray polymerization methods. The coating formed using chemical polymerization methods had lower surface resistivity than that formed by direct application of a soluble polymer.

It was observed that applied coatings of poly(3-decanylpyrrole) showed a smoother surface morphology with a more even dispersion compared to those formed by chemical methods.

Failure of conjugated linoleic acid supplementation to enhance biosynthesis of docosahexaenoic acid from α-linolenic acid in healthy human volunteers

A rate-limiting step in docosahexaenoic acid (DHA) formation from α-linolenic acid (ALA) involves peroxisomal oxidation of 24:6n-3 to DHA. The aim of the study was to determine whether conjugated linoleic acid (CLA) would enhance conversion of ALA to DHA in humans on an ALA-supplemented diet. The subjects (n=8 per group) received daily supplementation of ALA (11g) and either CLA (3.2g) or placebo for 8 weeks. At baseline, 4 and 8 weeks, blood was collected for plasma fatty acid analysis and a number of physiological measures were examined. The ALA-supplemented diet increased plasma levels of ALA and eicosapentaenoic acid (EPA). The addition of CLA to the ALA diet resulted in increased plasma levels of CLA, as well as ALA and EPA. Plasma level of DHA was not increased with either the ALA alone or ALA plus CLA supplementation. The results demonstrated that CLA was not effective in enhancing DHA levels in plasma in healthy volunteers.

Preliminary investigations into using eugenol to recover erased characters on polymers

In this paper we present our preliminary studies on the efficacy of eugenol for the recovery of erased characters on polymers. We have found that eugenol rapidly recovers erased characters when applied to the surface of polymer substrates. By applying eugenol to the surface to be treated using a cotton bud or paintbrush, we were able to revisualize erased characters from a range of polymers, inclluding acrylonitrile butadiene styrene, acrylic, high-impact polystrene, and polystyrene. Eugenol is safe, nonhazardour, and easily sourced reagent for this purpose.

Effects of dietary fat and conjugated linoleic acid on plasma metabolite concentrations and metabolic responses to homeostatic signals in pigs

Sixteen female cross-bred (Large White × Landrace) pigs (initial weight 65 kg) with venous catheters were randomly allocated to four treatment groups in a 2×2 factorial design. The respective factors were dietary fat (25 or 100 g/kg) and dietary conjugated linoleic acid (CLA; 0 or 10 g CLA-55/kg). Pigs were fed every 3 h (close to ad libitum digestible energy intake) for 8 d and were bled frequently. Plasma glucose and non-esterified fatty acid (NEFA) responses to insulin and adrenaline challenges were determined on day 8. Plasma concentrations of NEFA were significantly increased (10·5 and 5·4 % for low- and high-fat diets respectively, P=0·015) throughout the experiment, suggesting that there was a possible increase in fat mobilisation. The increase in lipolysis, an indicator of ß-adrenergic stimulated lipolysis, was also evident in the NEFA response to adrenaline. However, the increase in plasma triacylglycerol (11·0 and 7·1 % for low- and high-fat diets respectively, P=0·008) indicated that CLA could have reduced fat accretion via decreased adipose tissue triacylglycerol synthesis from preformed fatty acids, possibly through reduced lipoprotein lipase activity. Plasma glucose, the primary substrate for de novo lipid synthesis, and plasma insulin levels were unaffected by dietary CLA suggesting that de novo lipid synthesis was largely unaffected (P=0·24 and P=0·30 respectively). In addition, the dietary CLA had no effect upon the ability of insulin to stimulate glucose removal.

Dietary conjugated linoleic acid differentially alters fatty acid composition and increases conjugated linoleic acid content in porcine adipose tissue

Conjugated linoleic acids (CLA) have been shown to decrease body fat content in pigs. It is possible that feeding pigs diets rich in CLA may increase carcass lipid CLA to levels that could provide health benefits when included as a part of a healthy diet. Therefore, the aim of the present study was to determine whether dietary CLA supplementation has any effect on the fatty acid composition of subcutaneous and intramuscular adipose tissue in pigs. Thirty-five female cross bred (Large White X Landrace) pigs (initial weight 57·2 kg and initial P2 back fat 11·5 mm) were used in the present study. Pigs were housed individually and randomly allocated to one of six dietary treatments (0·00, 1·25, 2·50, 5·00, 7·50 and 10·00 g CLA55 (55 g CLA isomers/100 g total fatty acids; Natural Lipids Ltd, Hovdebygda, Norway)/kg)
and fed their respective diets for 8 weeks. Twelve CLA isomers in the diet and in pig tissue lipids were separated by Agþ-HPLC. CLA was incorporated at fivefold higher levels in subcutaneous fat as compared with intramuscular fat and in a dose-dependant manner. Overall, the transfer efficiency of CLA was maximized at 5·00 g CLA55/kg. However, there was clear selectivity in the uptake or incorporation of cis,trans-9,11 isomer over the trans,cis-10,12 isomer. In general, CLA supplementation produced significant changes in skeletal muscle and adipose tissue fatty acid composition, indicating that dietary CLA had a potent affect on lipid transport and metabolism in vivo. Significant increases in myristic, palmitic and palmitoleic acids and a reduction in arachidonic acid were observed, suggesting an alteration in
activity of Δ5-, Δ6- and Δ9-desaturases in pig adipose tissue. In conclusion, feeding pigs diets supplemented with CLA increases carcass lipid CLA, but also results in changes in the fatty acid profile in pig fat that could potentially outweigh the benefits of CLA.

Conjugated linoleic acid decreases fat accretion in pigs evaluation by dual-energy X-ray absorptiometry

Thirty female Large White × Landrace pigs (average weight 57·2 (SD 1·9) kg) were allocated to one of six dietary treatments containing 0, 1·25, 2·5, 5·0, 7·5 or 10·0 g 55 % conjugated linoleic acids (CLA) isomers (CLA-55)/kg diet and fed for 8 weeks. Each pig was scanned at 0, 28 and 56 d and again at post slaughter using dual-energy X-ray absorptiometry (DXA) to determine the temporal pattern of body composition responses. Values determined by DXA were adjusted using regression equations generated from validation experiments between chemically and DXA-predicted values. Overall, there was a significant linear reduction in fat content with the increasing levels of CLA in the diet (P=0·007, P=0·011, P=0·008 at week 4, week 8 and for the carcass, respectively). The greatest improvement was recorded at the early stages of CLA supplementation and for the highest dose of CLA (week 4, -19·2 % compared with week 8, -13·7 %). In the first 4 weeks of feeding CLA, pigs receiving 10 g CLA-55/kg diet deposited 93 g less fat/d than pigs fed basal diets (P=0·002) compared with only 6 g less fat than control animals in the final 4 weeks. Lean content and lean deposition rate were maximised at 5 and 2·5 g CLA-55/kg diet for the first 4 weeks (P=0·016) and the final 4 weeks of treatment (P=0·17), respectively. DXA estimates of bone mineral content and bone mineral density were not affected by CLA supplementation throughout the experiment. These data demonstrate that dietary CLA decreases body fat in a dose-dependent manner and that the response is greatest over the initial 4 weeks of treatment.

Effects of dietary conjugated linoleic acid on haematological and humoral responses in the grower pig

The effects of conjugated linoleic acid (CLA) on the levels of total serum leucocytes, granulocytes including neutrophils, basophils, and eosinophils, as well as on monocytes and leucocytes were measured in pigs selected from a clean (minimal disease) herd. Thirty pigs were fed different rates of dietary CLA (0, 1.25, 2.5, 5.0, 7.5, and 10.0 g CLA-55/kg diet) for 8 weeks. Blood samples were collected at the end of the study for assessment of haematological and humoral responses to CLA supplementation. No difference in total white blood cells including the neutrophil, monocyte, and lymphocyte counts was observed among different dietary groups. A dose-dependent reduction (P = 0.02) in eosinophil concentrations suggests that CLA exerts anti-inflammatory activities. A 2-fold increase in the level of basophils was recorded in pigs fed lower levels of CLA (1.25 and 2.5 g CLA/kg diet) but the levels decreased gradually (P = 0.05) and were below the detection limit at the highest rate (10 g/kg) of CLA supplementation. The level of IgG was reduced by over 50% in CLA-fed pigs (P < 0.001), although the response was quadratic in nature (P < 0.001). T-cell population analysis showed that CD4+ cells tended (P = 0.06) to be reduced linearly with increasing inclusion of CLA in the diet. Our results suggest that dietary CLA modulates haematological and humoral responses in a dose-dependent manner.

Dietary conjugated linoleic acid improves carcass leanness without altering meat quality in the growing pig

One constraint facing the pig industry is that ad libitum feeding can often result in high levels of body fat and technologies which can reduce the ratio of lean to fat deposition in the pig are continually being explored. Conjugated linoleic acids have been shown to decrease body fat content in pigs. Therefore, the aim of this study was to determine whether dietary conjugated linoleic acids supplementation has any effect on meat quality and carcass characteristics in finisher pigs. Sixty female crossbred (Large White × Landrace) pigs (average initial weight 56.6 ± 1.9 kg and average initial P2 backfat 11.4 ± 1.3 mm) were used in the present study. Pigs were individually housed and randomly allocated to 1 of 6 dietary treatments: 0, 0.125, 0.25, 0.50, 0.75 or 1.0% (w/w) of conjugated linoleic acids-55. The wheat-based diets were formulated to contain 14.3 MJ DE and 9.3 g available lysine per kg and were fed ad libitum for 8 weeks. Pigs were slaughtered and meat quality was determined on the longissimus thoracis using standard techniques. Dietary conjugated linoleic acids reduced subcutaneous back fat in a linear manner with effects being most pronounced in the middle back fat layer. There was also a linear (P<0.001) decrease in intramuscular fat with increasing dietary conjugated linoleic acids supplementation. However, there was no effect of conjugated linoleic acids on subjective measures of marbling of the loin. Also, loin muscle ultimate pH (P = 0.94), lightness values (P = 0.46) subjective colour scores (P = 0.79), cooking loss (P = 0.71), drip loss (P = 0.40), shear force (P = 0.61) and subjective measures of wetness/firmness (P = 0.19) were unaffected. Dietary conjugated linoleic acids did not alter oxidation, as measured by the level of TBARs at day 1 post-slaughter (P = 0.38) or after 9 days of simulated retail display (P = 0.35). These data confirm that dietary conjugated linoleic acids can improve carcass quality by decreasing back fat depths without having any detrimental effects on meat quality.