Analysis of Dispersion in Ferrite-superconductor Layered Structures

This paper studies electromagnetic wave propagation in hybrid structures consisting of ferrite and superconducting films. Dispersion relations for transverse electric mode of propagation are derived. Numerical results are presented for two specific structures viz. a ferrite/superconductor structure and a ferrite/superconductor/ferrite structure and dependence of propagation on various structural parameters and frequency are determined. The non-reciprocal nature of propagation is also established.     

Local calcium signalling by inositol-1,4,5-trisphosphate in Purkinje cell dendrites

The second messenger inositol-1,4,5-trisphosphate (InsP3) releases Ca2+ from intracellular Ca2+ stores by activating specific receptors on the membranes of these stores. In many cells, InsP3 is a global signalling molecule that liberates Ca2+ throughout the cytoplasm. However, in neurons the situation might be different, because synaptic activity may produce InsP3 at discrete locations. Here we characterize InsP3 signalling in postsynaptic cerebellar Purkinje neurons, which have a high level of InsP3 receptors. We find that repetitive activation of the synapse between parallel fibres and Purkinje cells causes InsP3-mediated Ca2+ release in the Purkinje cells. This Ca2+ release is restricted to individual postsynaptic spines, where both metabotropic glutamate receptors and InsP3 receptors are located, or to multiple spines and adjacent dendritic shafts. Focal photolysis of caged InsP3 in Purkinje cell dendrites also produces Ca2+ signals that spread only a few micrometres from the site of InsP3 production. Uncaged InsP3 produces a long-lasting depression of parallel-fibre synaptic transmission that is limited to synapses where the Ca2+ concentration is raised. Thus, in Purkinje cells InP3 acts within a restricted spatial range that allows it to regulate the function of local groups of parallel-fibre synapses.     

Time-Overrun Factors in Nigerian Construction Industry

Factors that affect time overrun in the Nigerian construction industry have been studied, and the rank agreement factor for the professionals are architects∕engineers, 0.75; architects∕builders, 0.83; quantity surveyors∕engineers, 0.74; quantity surveyors∕builders, 0.79; and engineers∕builders, 0.69. Important findings are (1) the degree of occurrence of time overrun is high—between 80 and 90%; (2) relative contributions of the client, contractor, and others are 62, 32, and 6%, respectively; (3) time overrun is more pronounced in government/public sector projects (89%); and (4) time overrun occurs on all projects, irrespective of size.     

抗性淀粉的研究与分析

抗性淀粉是摄食后不被小肠消化而能被大肠微生物群作用的那部分淀粉。已有关于食物中抗性淀粉测定的报道。本文综述了近来抗性淀粉研究进展以及相应的测定方法。本文所述的测定方法有较高的准确性和较好的重现性,能测定含量在1％以下的抗性淀粉。抗性淀粉对健康有潜在意义,以后将更注重这方面的研究。     

Did BP Atone for its Transgressions? Expanding Theory on ‘Ethical Apology’ in Crisis Communication

Ethical communication during crisis response is often assessed by external perceptions of the organization's intentions, rather than an assessment of the organization's communicative behaviors. This can easily lead researchers to draw editorial conclusions about an organization's ethics in crisis response rather than accurately describing its communicative behaviors. The case of BP's 2010 oil spill in the Gulf of Mexico provides a prime example for the importance of accurately assessing the ethical content of an organization's crisis response because the ethics of BP's response have been discussed in news and academic sources; yet little direct examination of the ethical content in BP's response has occurred. The findings have implications for communication ethics, social media engagement, and crisis communication more generally.     

End‐functionalized thermoplastic‐toughened phthalonitrile composites: influence on cure reaction and mechanical and thermal properties

Phthalonitrile polymers are known for their high thermal stability and good mechanical properties. However, their brittle nature limits their application as structural composites in many critical areas. The present study investigates the feasibility of toughening novolac–phthalonitrile (NPN) resin using chemically modified poly(ether ether ketone) (PEEK). A telechelic PEEK bearing a phthalonitrile end group (PEEKPN) was synthesized via nucleophilic substitution of nitrophthalonitrile with the corresponding phenol–telechelic poly(ether ether ketone) (PEEKOH). Different compositions of NPN and PEEKOH–PEEKPN blends with curing agent, i.e. diaminodiphenylsulfone, were investigated for their cure behaviour and mechanical properties of their carbon fabric composites. In NPN–PEEKOH blends, crosslinking of the phthalonitrile groups was facilitated by phenol‐mediated reactions resulting in the reduction of cure temperatures by around 130 °C with substantial improvement in thermal stability. Blending the resin with the thermoplastic enhanced the mechanical properties of the composites. The apparent flexural strength and impact strength of carbon fabric‐reinforced composites were improved by more than 200 and 150%, respectively, on incorporation of 20 wt% PEEKOH in the NPN matrix. However, higher concentration of PEEKOH had a detrimental effect on the properties. Substitution of phenol end groups by phthalonitrile moieties led to integration of the PEEK moieties with the NPN matrix. However, it was not as conducive as PEEKOH for improving the matrix properties. The better performance of PEEKOH is attributed to the formation of polar heterocyclic groups like isoindoline by way of the phenol–nitrile reaction. © 2014 Society of Chemical Industry     

Fluctuating water table effect on phosphorus release and availability from a Florida Spodosol

Spodosols in Florida exhibit a unique hydrology including a fluctuating water table that can often reach the surface horizon during the summer months. This paper evaluated the effects of fluctuating water table on P fluxes and availability in a typical Florida Spodosol. The study was conducted on an established bahiagrass (Paspalum notatum Flügge) pasture grown on a Smyrna sand (sandy, siliceous, hyperthermic Aeric Alaquods). Phosphorus fluxes were measured using suction cup lysimeters installed at depths of 15, 30, 60, 90, and 150 cm. The 15- and 30-cm deep lysimeters were located above the spodic (Bh) horizon, whereas the remaining lysimeters (60-, 90- and 150-cm) were below the Bh horizon. A pressure transducer was installed at the center of the experimental site to monitor changes in water table depth. Two anion exchange membranes (2 × 6 cm) were buried in each plot at a 15-cm depth to estimate in situ P availability. During the 2-year study, leachate P concentrations in the lysimeters above the Bh horizon increased as water tables rose in the months of August and September. Conversely, P concentration measured in the lysimeters below the Bh horizon remained relatively constant (0.02 mg L⁻¹). Soil P availability also increased (from 3.2 μg cm⁻² in June to 9.2 μg cm⁻² in August) in response to rising water table. Results showed that the fluctuating water table conditions experienced during the summer months in Florida cause upward flux of P from the Bh horizon, which increased soil P availability and susceptibility to off-site transport.