Consequences of intraspecific seed-size variation in Sparganium emersum for dispersal by fish

1. The potential for seed dispersal by fish (ichthyochory) is likely to vary within aquatic plant species, depending on intraspecific variation in phenotypic seed traits.

2. We studied the effect of seed size variation within the unbranched burreed (Sparganium emersum) on the potential for internal dispersal by the common carp (Cyprinus carpio), by feeding them light (< 10 mg), medium (10–20 mg) and heavy ( > 20 mg) seeds, seed mass being positively related to seed size.

3. We hypothesized: (i) that ingestion, retention time, survival during gut passage and viability after gut passage of S. emersum seeds would be affected by seed size; and (ii) that this would translate into intraspecific variation in dispersal probability and dispersal distance among seed size categories.

4. Ingestion was negatively related to seed size, while survival during gut passage was positively related to seed size. Seed viability after gut passage was not affected by seed size. Since the negative effect of ingestion was counterbalanced by an equally strong but positive effect on seed survival, the probability of dispersal did not differ between the tested seed-size categories.

5. The time that seeds remained in the digestive tract of carp did not differ between seed sizes, suggesting equal potential dispersal distances for all seeds. Based on optimum swimming speeds of carp, ranging from 0·9 to 1·8 km h−1, maximum dispersal distances will most likely range from 13·5 to 27 km.

6. This study highlights the importance of studying all stages of the endozoochorous dispersal process in order to estimate the effect of a phenotypic seed trait on plant dispersal.

The effect of seed morphology on the potential dispersal of aquatic macrophytes by the common carp (Cyprinus carpio)

1. The potential for seed dispersal by fish (ichthyochory) will vary among aquatic plants because of differences in seed size and morphology.

2. To examine how seed morphology influences the probability of dispersal by the common carp (Cyprinus carpio), we studied seed ingestion, retention time and subsequent egestion and germination of seeds of Sparganium emersum and Sagittaria sagittifolia, two aquatic plant species with similar sized but morphologically different seeds.

3. We compared dispersal probabilities between the two plant species, in which the probability of dispersal is assumed to be a function of the probabilities of seed ingestion, egestion and germination, and the dispersal distance is assumed to be a function of seed egestion rate over time.

4. We found that, although the soft seeds of S. sagittifolia had an approximately 1.5 times higher probability of being ingested by the carp than the hard seeds of S. emersum (83.15% ± 1.8% versus 56.16% ± 2.7%, respectively), the latter had an almost twofold higher probability of surviving the passage through the digestive tract (38.58% ± 2.7% versus 20.97% ± 1.5%, respectively). Patterns of seed egestion over time did not differ between the two plant species, despite the difference in seed morphology. Gut passage had a different effect on seed germination between plant species. Compared with non-ingested controls, seeds of S. emersum showed a 12.6% increase in germination and a 2.1 day acceleration in germination rate, whereas seeds of S. sagittifolia displayed a 47.3% decrease and 5.1 day delay, respectively.

5. Our results suggest that seed morphology affects the dispersal probability and postdispersal establishment, but not the dispersal distance, of aquatic plants that are dispersed by fish.

Breakfast size is related to body mass index for men, but not women

The objective of this study was to examine the effect of self-reported breakfast size, daily eating, and other health habits on body mass index (BMI). We hypothesized that a consumption of a substantial breakfast compared with skipping or small breakfasts would be associated with lower BMI. Three independent, cross-sectional, screening surveys were conducted by Sydney Adventist Hospital in 1976, 1986, and 2005 in the surrounding community. The archived survey forms of 384 men and 338 women in 1976, 244 men and 229 women in 1986, and 270 men and 62 women in 2005 were randomly selected. Body mass index was determined from height and weight measured by hospital staff. The reported amount consumed at breakfast was one of several eating habits that predicted BMI for men but not women. It explained 5% to 6% of the variance in male BMI in all 3 years examined. As the reported breakfast amount increased, men's BMI decreased. Lifestyle confounders including vegetarianism and physical activity did not affect this relationship. However, the consumption of breakfast was significantly positively associated with consumption of cereals, bread, fruit, and spreads, while coffee consumption was significantly associated with smaller breakfasts or breakfast skipping. The consumption of relatively large breakfasts may influence BMI in men, and its promotion may help reduce the prevalence of obesity in Australia and elsewhere.

Effect of nano-Al2O3 addition on the densification of YSZ electrolytes

This work investigates the effect of nanosized Al2O3 addition on the sinterability of YSZ electrolyte. (1-x)YSZ + Al2O3 ceramics with compositions x = 0 to 0.01 were prepared by the conventional mixed oxide route from a commercial powder suspension (particle size <50 nm), and sintered at 1200 to 1500 degrees C for 2 hours in air. Densification, phase evolution, and microstructure were characterized by SEM/EDS and XRD. An improvement in sintered density was observed for the samples with 0.2 to 0.5 mol% Al2O3, though depending on the sintering temperature. Only cubic zirconia was detected as crystalline phase, although XRD features suggested chemical interactions depending upon the amount of Al2O3. The grain size of YSZ was homogeneous and no second phase segregation was detected in the tested range of incorporated nano-Al2O3 and sintering temperatures.

Effect of natural organic compounds on the removal of organic carbon in coagulation and flocculation processes

Natural organic matter (NOM) in water contains organic compounds that are both hydrophobic and hydrophilic with a wide range of molecular weights. It is composed of non-homogeneous organic compounds such as humic substances, amino acids, sugars, aliphatic and aromatic acids, and other chemical synthetic organic matters. NOM in water is a major concern not only because of its contribution to the formation of disinfection by-products (DBPs) and taste and odor, but also its influence on the demand for coagulants and disinfectants, the removal efficiency of water treatment processes, etc. This research aims at identifying the influence of NOM in coagulation and flocculation processes in order to optimize the coagulation and flocculation conditions. In this study, pretreated pond water was used as the source water. It was observed from the experimental results that: (1) The optimum pH for coagulation to remove NOM is around 7. (2) The optimum alum dose at this pH can vary from 125-1,225 mgl-1 when the TOC is increased from 4 to 25 mgl-1. (3) The presence of secondary compounds such as Ca2+, Mg2+ divalent cations had no significant effect on the removal of organic matter. (4) The presence of clay increased the organic removal by 15%. (5) The organic compound with higher molecular weight has higher removal affinity in coagulation process. (6) Floc size and settling velocity of floc and sludge production all increased with the increase in NOM concentration. From the results of Capillary Suction Time (CST) tests, the floc formed with lower TOC readily released the water to make the dewatering process easier. (7) The organic removal efficiency was significantly different for natural water containing non-homogeneous organic compounds compared to the synthetic water containing humic acid only (homogeneous organic matter). For example, the NOM removal efficiency was 80% for the synthetic water containing humic acid with TOC of 7 mgl-1 at pH 7; but the NOM removal for the pretreated pond water was 60%.

Effect of tool speeds during friction stir lap welding on mode of fracture and fracture strength of Al 6060-T5 joints

Friction stir lap welding (FSLW) of an age hardened Al alloy and evaluations of how FS speeds affected hooking and how hooking and softening due to FS affected fracture strength of the lap welds have been conducted. It was found that increasing rotation speed and reducing welding speed (v) increased the stir zone size (AB-SZ) and also hook size (h), although a maximum value of h (hMax) reached. The features of hooks for the observed - AB-SZ-h relationships are presented and explained. It was found that when h increased to a value of ~ 0.9 mm (for the 3 mm alloy sheets), it started to invoke a significant effect on reducing fracture strength. Factors such as FS softening and insufficient joining, limited the fracture strength of the lap welds for small h values and these are presented and discussed.