Comparative analysis of performance and stability among composite cross populations, variety mixtures and pure lines of winter wheat in organic and conventional cropping systems

This study investigated the effects of increased genetic diversity in winter wheat (Triticum aestivum L.), either from hybridization across genotypes or from physical mixing of lines, on grain yield, grain quality, and yield stability in different cropping environments. Sets of pure lines (no diversity), chosen for high yielding ability or high quality, were compared with line mixtures (intermediate level of diversity), and lines crossed with each other in composite cross populations (CCPn, high diversity). Additional populations containing male sterility genes (CCPms) to increase outcrossing rates were also tested. Grain yield, grain protein content, and protein yield were measured at four sites (two organically-managed and two conventionally-managed) over three years, using seed harvested locally in each preceding year. CCPn and mixtures out-yielded the mean of the parents by 2.4% and 3.6%, respectively. These yield differences were consistent across genetic backgrounds but partly inconsistent across cropping environments and years. Yield stability measured by environmental variance was higher in CCPn and CCPms than the mean of the parents. An index of yield reliability tended to be higher in CCPn, CCPms and mixtures than the mean of the parents. Lin and Binns’ superiority values of yield and protein yield were consistently and significantly lower (i.e. better) in the CCPs than in the mean of the parents, but not different between CCPs and mixtures. However, CCPs showed greater early ground cover and plant height than mixtures. When compared with the (locally non-predictable) best-yielding pure line, CCPs and mixtures exhibited lower mean yield and somewhat lower yield reliability but comparable superiority values. Thus, establishing CCPs from smaller sets of high-performing parent lines might optimize their yielding ability. On the whole, the results demonstrate that using increased within-crop genetic diversity can produce wheat crops with improved yield stability and good yield reliability across variable and unpredictable cropping environments.

Energetics and stability of vacancies in carbon nanotubes

In this work we present ab initio calculations of the formation energies and stability of different types of multi-vacancies in carbon nanotubes. We demonstrate that, as in the case of graphene, the reconstruction of the defects has drastic effects on the energetics of the tubes. In particular, the formation of pentagons eliminates the dangling bonds thus lowering the formation energy. This competition leads to vacancies having an even number of carbon atoms removed to be more stable. Finally the appearance of magic numbers indicating more stable defects can be represented by a model for the formation energies that is based on the number of dangling bonds of the unreconstructed system, the pentagons and the relaxation of the final form of the defect formed after the relaxation. (C) 2011 Elsevier Ltd. All rights reserved.

Thermal behavior and stability of biodegradable spray-dried microparticles containing triamcinolone

Thermal analysis has been widely used for obtaining information about drug-polymer interactions and for pre-formulation studies of pharmaceutical dosage forms. In this work, biodegradable microparticles Of Poly (D,L-lactide-co-glycolide) (PLGA) containing triamcinolone (TR) in various drug:polymer ratios were produced by spray drying. The main purpose of this study was to study the effect of the spray-drying process not only on the drug-polymer interactions but also on the stability of microparticles using differential scanning calorimetry (DSC), thermogravimetry (TG) and derivative thermogravimetry (DTG), X-ray analysis (XRD), and infrared spectroscopy (IR). The evaluation of drug-polymer interactions and the pre-formulation studies were assessed using the DSC, TG and DTG, and IR. The quantitative analysis of drugs entrapped in PLGA microparticles was performed by the HPLC method. The results showed high levels of drug-loading efficiency for all used drug: polymer ratio, and the polymorph used for preparing the microparticles was the form B. The DSC and TG/DTG profiles for drug-loaded microparticles were very similar to those for the physical mixtures of the components. Therefore, a correlation between drug content and the structural and thermal properties of drug-loaded PLGA microparticles was established. These data indicate that the spray-drying technique does not affect the physico-chemical stability of the microparticle components. These results are in agreement with the IR analysis demonstrating that no significant chemical interaction occurs between TR and PLGA in both physical mixtures and microparticles. The results of the X-ray analysis are in agreement with the thermal analysis data showing that the amorphous form of TR prevails over a small fraction of crystalline phase of the drug also present in the TR-loaded microparticles. From the pre-formulation studies, we have found that the spray-drying methodology is an efficient process for obtaining TR-loaded PLGA microparticles. (C) 2008 Elsevier B.V. All rights reserved.

Efficient and low cost devices for solar energy conversion: Efficiency and stability of some natural-dye-sensitized solar cells

Dye-sensitized solar cells, named by us Dye-Cells, are one of the most promising devices for solar energy conversion due to their reduced production cost and low environmental impact, especially those sensitized by natural dyes. The efficiency and stability of devices based on natural sensitizers such as mulberry (Morus alba Lam), blueberry (Vaccinium myrtillus Lam), and jaboticaba`s skin (Mirtus cauliflora Mart) were investigated. Dye-Cells prepared with aqueous mulberry extract presented the highest P(max) value (1.6 mW cm(-2)) with J(sc) = 6.14 mA cm(-2) and V(oc) = 0.49 V, Photoelectrochemical parameters of 16 cm(2) active area devices sensitized by mulberry dye were constant for 14 weeks of continuous evaluation. Moreover, the cell remained stable even after 36 weeks with a fairly good efficiency. Therefore, mulberry dye opens up a perspective of commercial feasibility for inexpensive and environmentally friendly Dye-Cells. (C) 2009 Elsevier B.V. All rights reserved.

Single transferable vote with Borda elimination: proportional representation, moderation, quasi-chaos and stability

Modifying single transferable vote (STV) by removing candidates according to their Borda scores creates a new vote counting system (STV-B) that is not quasi-chaotic, results in proportional representation, and promotes the election of moderate candidates. Dummett, M.A.E. [1997. Principles of Electoral Reform. Oxford University, New York] noted quasi-chaos in STV and proposed the “Quota/Borda system” (QBS) as a solution. STV-B and QBS retain proportional representation from STV, permit some influence on candidate selection to occur between voting blocks thereby promoting moderate results, and are much more stable than STV when subjected to small changes in voter preferences. Under STV-B, and not QBS, a minority that shares some preferences may elect a candidate even if the minority is not a solid coalition.

Prediction of children's flavour preferences. Effect of age and stability in reported preferences

The present study investigated whether children were able to communicate stable flavour preferences and whether mothers’ ability to correctly identify their child's flavour preferences is related to the stability of their child's flavour preferences. On 2 consecutive days, 75 girls and 77 boys (3–10 years, mean age = 7.1 ± 2.3 years) carried out a preference ranking task for five ice-cream flavours: mint, coffee, chocolate and two variants of vanilla. Without input from their child, mothers ranked four of these flavours according to their own understanding of their child's flavour preferences. Spearman rank order correlations suggest that older aged children (5–10 years) have more stable flavour preferences than younger aged children (3–5 years) (p < 0.05). Only 39% of mothers were able to correctly predict children's most preferred flavour, but significantly more parents (61%) were able to predict children's least preferred flavour (p < 0.05). Mothers’ ability to correctly predict their children's least preferred flavour seemed to be facilitated by children's ability to communicate their least preferred flavours in a consistent manner (p < 0.05). It is recommended to apply proper sensory methodologies with children rather than relying on mothers’ report when interested in children's likes. When interested in children's dislikes mothers’ report might be suitable.

Ordering and stability in conducting polypyrrole

X-ray diffraction (XRD) was employed to characterize electrochemically synthesized polypyrrole (PPy) films with 1,5-naphthalene disulfonate (1,5-NDS) counterions treated with simple acid and base. Results show that the as-synthesized film is amorphous with short-range ordering in the polymer backbone. This ordering is soon lost after thermal ageing at 150°C for 60 days and there is evidence of counterion degradation. Base treatment of the PPy/1,5-NDS films has similar effects leading to a complete loss of ordering in the polymer backbone and dedoping of the polymer. Acid treatment at high temperatures increases the ordering of the polymer backbone and results in the development of a secondary interdopant peak confirming that ion exchange has occurred. Conductivity of the PPy was also increased substantially. The enhanced ordering was maintained even after thermal ageing. Room-temperature acid treatment also results in improved ordering of the polymer as well as the counterion but the increase in conductivity is only marginal and most of the ordering is soon lost after thermal ageing. Increase in ordering of the polymer structure seems to lead to better conductivity, although not necessarily improved thermal stability.

Solubility and Stability of cytochrome c in hydrated ionic liquids : effect of oxo acid residues and kosmotropicity

Hydrated ionic liquids (ILs) were prepared by adding appropriate amounts of water to hydrophilic ILs. Some hydrated ILs show excellent solubilizing ability for proteins, keeping the basic properties of ILs. The solubility of cytochrome c (cyt c) depended on the structure of the component ions. When component anions have oxo acid residues, the resulting hydrated ILs solubilize cyt c quite well. In such hydrated ILs, the structure and activity of cyt c is influenced by the kosmotropicity of the component ions. We synthesized ILs from various ions having different kosmotropicity, including dihydrogen phosphate (dhp), dibutylphosphate, acetate, lactate, and methanesulfonate as anions. The activity of the dissolved cyt c depends on the permutations of kosmotropicity of the component ions. cyt c shows no structural change and retains its activity when dissolved in the hydrated choline dhp, which is an excellent combination of chaotropic cation and kosmotropic anion. Furthermore, cyt c dissolved in the hydrated choline dhp remained in a native state and was active after 18 months of storage at room temperature.

Oxidation and stability of food grade fish oil : role of antioxidants

Oxidation of lipids containing unsaturated fatty acids is a common and complicated phenomenon. Volatile compounds generated during the oxidation of fish oil contribute to the unfavourable flavours and odours of the oil and the food products containing them. Although the initial mechanism of the oxidation seems simple, the mechanism and product mix become much more complicated and unpredictable during its progress, depending upon factors including the nature of the substrate and its environment. Oxidation of unsaturated fatty acids such as oleic, linoleic, and α-linolenic, predominantly from vegetable oils, and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish or microbial oil, produce several types of flavour volatiles that affect the sensory properties of these oils. Antioxidants are commonly used to retard the oxidation and improve the quality of food-grade oils. This chapter will discuss mechanisms of lipid oxidation and methods to control lipid oxidation, including the use of antioxidants.