Electrospraying: an in-situ polymerisation route for fabricating high macroporous scaffolds

This paper reports a direct jet-based polymerisation by polycondensation approach to forming a self-supporting scaffold structure. The processing technique is electrospraying, which is also known as electrohydrodynamic atomization. A specially formulated ethanolic siloxane sol derived from alkoxysilanes was synthesised and electrosprayed using a ring-shaped ground electrode configuration. The medium was seen to electrospray in the stable cone-jet mode, which later gave rise to the growing or forming of “fir-tree” like structures. The materials were characterised using microscopy, solid state NMR, FTIR, XRD and DSC. Hence this paper explains the direct controlled polycondensation from the siloxane sol and further presents the basis by which these scaffolds take shape.     

Iso-N-formyl-5-en-chonemorphine, a steroidal alkaloid from Sarcococca zeylanica

Chemical investigation of the non-quaternary alkaloidal fraction of the aerial parts of Sarcococca zeylanica of the family Buxaceae furnished a steroidal alkaloid iso-N-formyl-5-en-chonemorphine, which has not been previously reported as a natural product. The structure of this alkaloid was established on the basis of spectroscopic evidence.     

Preparation of lead zirconate titanate nano-powder by electrohydrodynamic atomization

A lead zirconate titanate (PZT) sol was subjected to electrohydrodynamic atomization in the stable cone-jet mode. The droplets generated were sized by laser diffraction before deposition and heating to 600 °C. The droplets were 20–35 m in size and transmission electron microscopy showed that their relics consisted of PZT powder particles, <10 nm in size. Thus, a novel method of preparing nano-powders of functional advanced materials, such as PZT, has been pioneered. PACS 81.20.Ev; 81.20.Rg; 77.84.-s; 81.07.Bc     

Glycosides from Grewia damine and Filicium decipiens

Chemical investigation of n-butanol extract from the methanol extract of leaves of Grewia damine furnished lupeol, sitosterol beta-D-glucoside, flavone C-glycosides vitexin, isovitexin where as the same extracts from the leaves of Filicium decipiens furnished sitosterol beta-D-glucoside, 3-O-beta-D-glucopyranosyl kaempferol, 3-O-beta-D-glucopyranosylquercetin and 3-O-alpha-L-rhamnopyranosyl(1--> 2)-beta-D-glucopyranosylkaempferol.     

Stilbene derivatives with antifungal and radical scavenging properties from the stem bark of Artocarpus nobilis

Antifungal activity-guided fractionation of the n-butanol extract from the methanol extract of the stem bark of Artocarpus nobilis furnished two stilbene derivatives (E)-4-isopentenyl-3,5,2',4'-tetrahydroxystilbene and (E)-4-(3-methyl-E-but-1-enyl)-3,5,2',4'-tetrahydroxystilbene. Both compounds showed strong antifungal activity against Cladosporium cladosporioides and high radical scavenging activity towards the DPPH radical in TLC bio-autography method.     

Antifeedant activity of some Sri Lankan plants

Twenty nine solvent extracts from twenty Sri Lankan plants were examined for antifeedant activity against the fourth instar larvae of Mexican bean beetle, Epilachna varivestis Muls., Coccinellidae. Extracts of Sarcococca brevifolia (Buxaceae), Strychnus nux vomica (Loganiaceae), Diploclisia glaucescens, Coscinium fenestratum (Menispermaceae), Syzygium caryophyllatum (Myrtaceae), Pittosporium zeylanicum (Pittosporaceae), Lasianthus gardneri (Rubiaceae), Ferronia limonia (Rutaceae) and Allophylus cobbe (Sapindaceae) have shown strong antifeedant activity.     

Novel forming of single and multiple ceramic micro-channels

This paper reports a cost-effective processing route for forming micrometre-size channels containing multiple exits/entries. An alumina suspension was electrosprayed in the stable cone-jet mode and the fine ceramic droplets generated were deposited on an organic fibre, which was pre-shaped to the architecture of the micro-channel(s) required. The coated structure was heated to 1400 °C to pyrolyse the fibre and create the ceramic micro-channel(s). PACS 81.20.Rg; 81.05.Je; 07.10.Cm     

Self-assembled nanostructures via electrospraying

A concentrated nanoparticulate-based ethylene glycol suspension was prepared and electrosprayed at optimum and stable cone-jet mode conditions. Using laser spectroscopy, the droplets were measured and found to range within 0.23–3.8 μm. In parallel to spectroscopy-assisted sizing, a volume equivalence route for estimating droplet sizes was carried out by measuring contact angles and diameters of the deposits. The electrosprayed nanosuspension relics were examined using optical and transmission electron microscopy. These deposits were further characterized using energy-dispersive X-rays and selected area electron diffraction. Simultaneously deposits were formed by a controlled route through needle deposition without the presence of an electric field. The structures formed in this non-electric field driven route are compared with those formed with electric fields. Thus, elucidating electrosprays as a competing nanofabrication route for forming self-assemblies with a wide range of nanomaterials in the nanoscale for top-down based bottom-up assembly of structures.     

Simultaneous detection of ultraviolet and infrared radiation in a single GaN/GaAlN heterojunction

Results are presented for a dual-band detector that simultaneously detects UV radiation in the 250-360 nm and IR radiation in the 5-14 microm regions with near zero spectral cross talk. In this detector having separate UV- and IR-active regions with three contacts (one common contact for both regions) allows the separation of the UV and IR generated photocurrent components, identifying the relative strength of each component. This will be an important development in UV-IR dual-band applications such as fire-flame detection, solar astronomy, and military sensing, eliminating the difficulties of employing several individual detectors with separate electronics-cooling mechanisms.