Seed development, maturation and storage behaviour of Mimusops elengi L

Mass maturity (end of the seed-filling phase) occurred at about 72 days after flowering (DAF) in developing seeds of Mimusops elengi, at which time seed moisture content had declined to about 55%. The onset of ability to germinate was detected at 56 DAF and seeds showed 98% germination by 84 DAF. Tolerance of desiccation to 10% moisture content was first detected at 70 DAF and was maximal by 84 DAF. Delaying collection by a further 14 days to 98 DAF, when fruits began to be shed, reduced seed viability, particularly for seeds first dried to 10% moisture content. Hence the best time for seed collection appears to be about 14 days before fruits shed. In a separate investigation with six different seed lots, desiccation below about 8-12% moisture content reduced viability (considerably in some lots). The viability of dry seeds (below about 10% moisture content) stored hermetically was reduced at cool temperatures (5 degrees C and below), and none survived storage at sub-zero temperatures. The results suggest that Mimusops elengi shows intermediate seed storage behaviour and that the optimal hermetic seed storage environment is about 10% moisture content at 10 degrees C, while short-term, moist, aerated storage at high (40%) moisture content is also feasible.

Dynamics and foraging behaviour of adult hornet robberflies, Asilus crabroniformis: implications for conservation strategy

Mark resighting studies of the hornet robberfly, Asilus crabroniformis, were carried out during the flight seasons of 1999 and 2000 on agricultural land on the Chilterns in Oxfordshire, UK. Six patches of land were identified which contained characteristics thought to be attractive to hornet robberflies. One hundred and twenty eight adults were marked in 1999 and 257 in 2000. Marking was carried out on one of the patches, but resighting observations were collected from all six sites. The daily population sizes were estimated using the Jolly-Seber method. The daily population size peaked between 50 and 72 from 23 August until 13 September in 2000. This was very similar to the peak population size of between 50 and 74 estimated for 1999. Adults were found to be capable of living for nearly 5 weeks. The maximum linear distance from the point of marking that any individual moved across the study site was 625 m, but some individuals moved over 400 m in a single day. Unsuitable habitat (suburban gardens and a main road) did not present a barrier to dispersal. Males were more likely than females to loiter in sites peripheral to the breeding site, whilst females seemed to be more tied to the breeding site. Most adults were caught from dung piles, but insects avoided fresh dung and preferred instead dung that was well into the process of drying out. A variety of insect species were taken as prey, including many beetles and flies. The findings of the study are discussed in relation to the management of the landscape to enhance the long-term prospects of the hornet robberfly in the UK, and to achieve the UK Biodiversity Action Plan target for this species.

Synthesis, structural analysis, and magnetic behaviour of three fumarate bridged coordination polymers: five-fold interpenetrated diamond-like net of Ni-II, sheets of Ni-II and Co-II

The hydrothermal reactions of Ni(NO3)(2).6H(2)O, disodium fumarate (fum) and 1,2-bis(4-pyridyl)ethane (bpe)/1,3-bis(4-pyridyl) propane (bpp) in aqueous-methanol medium yield one 3-D and one 2-D metal-organic hybrid material, [Ni(fum)(bpe)] (1) and [Ni(fum)(bpp)(H2O)] (2), respectively. Complex 1 possesses a novel unprecedented structure, the first example of an "unusual mode" of a five-fold distorted interpenetrated network with metal-ligand linkages where the four six-membered windows in each adamantane-type cage are different. The structural characterization of complex 2 evidences a buckled sheet where nickel ions are in a distorted octahedral geometry, with two carboxylic groups, one acting as a bis-chelate, the other as a bis-monodentate ligand. The metal ion completes the coordination sphere through one water molecule and two bpp nitrogens in cis position. Variable-temperature magnetic measurements of complexes 1 and 2 reveal the existence of very weak antiferromagnetic intramolecular interactions and/or the presence of single-ion zero field splitting (D) of isolated Ni-II ions in both the compounds. Experimentally, both the J parameters are close, comparable and very small. Considering zero-field splitting of Ni-II, the calculated D values are in agreement with values reported in the literature for Ni-II ions. Complex 3, [{Co(phen)}(2)(fum)(2)] (phen=1,10-phenanthroline) is obtained by diffusing methanolic solution of 1,10-phenanthroline on an aqueous layer of disodium fumarate and Co(NO3)(2).6H(2)O. It consists of dimeric Co-II(phen) units, doubly bridged by carboxylate groups in a distorted syn-syn fashion. These fumarate anions act as bis-chelates to form corrugated sheets. The 2D layer has a (4,4) topology, with the nodes represented by the centres of the dimers. The magnetic data were fitted ignoring the very weak coupling through the fumarate pathway and using a dimer model.

Discrepancy between parental reports of infants' receptive vocabulary and infants' behaviour in a preferential looking task

Two experiments are described which explore the relationship between parental reports of infants' receptive vocabularies at 1; 6 (Experiment 1a) or 1-3, 1;6 and 1;9 (Experiment 1b) and the comprehension infants demonstrated in a preferential looking task. The instrument used was the Oxford CD1, a British English adaptation of the MacArthur-Bates CD1 (Words & Gestures). Infants were shown pairs of images of familiar objects, either both name-known or both name-unknown according to their parent's responses on the CD1. At all ages, and on both name-known and name-unknown trials, preference for the target image increased significantly from baseline when infants heard the target's label. This discrepancy suggests that parental report underestimates infants' word knowledge.

Rheological and thermal behaviour of poly(N-isopropylacrylamide)/alginate smart polymeric networks

Interpenetrating polymeric networks based on sodium alginate and poly(N-isopropylacrylamide) (PNIPAAm) covalently crosslinked with N,N′-methylenebisacrylamide have been investigated using rheology, thermogravimetry, differential scanning calorimetry, X-ray diffraction measurements and scanning electron microscopy (SEM). An improved elastic response of the samples with a higher PNIPAAm content and increased amount of crosslinking agent was found. The temperature-responsive behaviour of the hydrogel samples was evidenced by viscoelastic measurements performed at various temperatures. It is shown that the properties of these gels can be tuned according to composition, amount of crosslinking agent and temperature changes. X-ray scattering analysis revealed that the hydrophobic groups are locally segregated even in the swollen state whilst cryo-SEM showed the highly heterogeneous nature of the gels.

Synthesis and phase behaviour of a homologous series of polymethacrylate-based side-chain liquid crystal polymers

The homologous series of side chain liquid crystal polymers, the poly[x-(4-methoxyazobenzene- 40-oxy)alkyl methacrylate]s, has been prepared in which the length of the flexible alkyl spacer has been varied from 3 to 11 methylene units. All the polymers exhibit liquid crystalline behaviour. The propyl and butyl members show exclusively nematic behaviour. The pentyl, hexyl, octyl and decyl members show a nematic and a smectic A phase while the heptyl, nonyl and undecyl homologues exhibit only a smectic A phase. The smectic A phase has been studied using X-ray diffraction and assigned as a smectic A1 phase in which the side chains are fully overlapped and the backbones are confined to lie between the smectic layers. For the nonyl member an incommensurate smectic phase is observed. The dependence of the transition temperatures on the length of the flexible spacer is understood in terms of the average shapes of the side chains.

Passive urban ventilation by combined buoyancy-driven slope flow and wall flow: Parametric CFD studies on idealized city models

This paper reports the results of a parametric CFD study on idealized city models to investigate the potential of slope flow in ventilating a city located in a mountainous region when the background synoptic wind is absent. Examples of such a city include Tokyo in Japan, Los Angeles and Phoenix in the US, and Hong Kong. Two types of buoyancy-driven flow are considered, i.e., slope flow from the mountain slope (katabatic wind at night and anabatic wind in the daytime), and wall flow due to heated/cooled urban surfaces. The combined buoyancy-driven flow system can serve the purpose of dispersing the accumulated urban air pollutants when the background wind is weak or absent. The microscopic picture of ventilation performance within the urban structures was evaluated in terms of air change rate (ACH) and age of air. The simulation results reveal that the slope flow plays an important role in ventilating the urban area, especially in calm conditions. Katabatic flow at night is conducive to mitigating the nocturnal urban heat island. In the present parametric study, the mountain slope angle and mountain height are assumed to be constant, and the changing variables are heating/cooling intensity and building height. For a typical mountain of 500 m inclined at an angle of 20° to the horizontal level, the interactive structure is very much dependent on the ratio of heating/cooling intensity as well as building height. When the building is lower than 60 m, the slope wind dominates. When the building is as high as 100 m, the contribution from the urban wall flow cannot be ignored. It is found that katabatic wind can be very beneficial to the thermal environment as well as air quality at the pedestrian level. The air change rate for the pedestrian volume can be as high as 300 ACH.

Comparative study of the performance of the M-cycle counter-flow and cross-flow heat exchangers for indirect evaporative cooling - paving the path towards sustainable cooling of buildings

This paper provides a comparative study of the performance of cross-flow and counter-flow M-cycle heat exchangers for dew point cooling. It is recognised that evaporative cooling systems offer a low energy alternative to conventional air conditioning units. Recently emerged dew point cooling, as the renovated evaporative cooling configuration, is claimed to have much higher cooling output over the conventional evaporative modes owing to use of the M-cycle heat exchangers. Cross-flow and counter-flow heat exchangers, as the available structures for M-cycle dew point cooling processing, were theoretically and experimentally investigated to identify the difference in cooling effectiveness of both under the parallel structural/operational conditions, optimise the geometrical sizes of the exchangers and suggest their favourite operational conditions. Through development of a dedicated computer model and case-by-case experimental testing and validation, a parametric study of the cooling performance of the counter-flow and cross-flow heat exchangers was carried out. The results showed the counter-flow exchanger offered greater (around 20% higher) cooling capacity, as well as greater (15%–23% higher) dew-point and wet-bulb effectiveness when equal in physical size and under the same operating conditions. The cross-flow system, however, had a greater (10% higher) Energy Efficiency (COP). As the increased cooling effectiveness will lead to reduced air volume flow rate, smaller system size and lower cost, whilst the size and cost are the inherent barriers for use of dew point cooling as the alternation of the conventional cooling systems, the counter-flow system is considered to offer practical advantages over the cross-flow system that would aid the uptake of this low energy cooling alternative. In line with increased global demand for energy in cooling of building, largely by economic booming of emerging developing nations and recognised global warming, the research results will be of significant importance in terms of promoting deployment of the low energy dew point cooling system, helping reduction of energy use in cooling of buildings and cut of the associated carbon emission.