High density culture of marine microalgae using semi-continuous and continuous systems.

This study entitled "High density culture o f marine micro-algae using semicontinuous and continuous systems" was carried out with the objectives of devising small-scale low cost systems for use in laboratory conditions. The study was carried out using two commonly used species of microalgae viz., the flagellate Isochrysis galbana and the diatom, Chaetoceros sp. The system devised was a modified turbidostat (2 1 to 5 1) having three tier gravitational flow with manual controllers and without automation. For scale-up semicontinuous culture, a 60 1 capacity internally illuminated plexy glass culture system was devised. Using 2.5 times the normal nutrient concentration, limited supply o f CO2 , activated charcoal filtered air and under sterile conditions it was possible to obtain upto 5 fold increase in culture cell density when compared to the normal batch cultures. Besides it was possible to maintain the cultures for durations varying from 2 to 5 weeks without collapse. In the continuous culture system o f 2 I capacity . The daily harvest o f high density culture amounted to 500 ml, and in the semi-continuous system (4 1 capacity). The once-in-3 day harvest varied between 2-3 litres. From a single 60 1 capacity semicontinuous system running for 36 days the total larvest amounted to 530 litres o f average 3.2 million cells/ml culture. With respect to maricuhure, the application of conclusions derived from present.work would resut in increased efficiency and reduced cost of production of microalgae

Laboratory - scale high density culture of the marine diatom Chaetoceros sp.

A laboratory scale continuous and semi-continuous system for culture of the marine diatom Chaetoceros sp. was devised. Using 2.5 times the normal nutrient concentration and limited supply of Co2, the culture density could be increased from an average 1.5 million cells / ml concentration in traditional batch culture systems to 13.7 million cells/ml in continuous system. Besides the increased biomass production, the duration of culture was enhanced to thirty days without crashing. The semi-continuous system was up-scaled to 60 1 capacity with an internal illumination system to yield 528 litres of average 3.2 million cells/ml within 36 days. The velocity of cell growth during the logarithmic phase in doublings/day ranged from 0.21 in control (batch culture) to 2.51 in the semi-continuous system. Furthermore, the cost of production, even with additional inputs, are comparable or even less than the traditional batch cultures. The economic efficiency was highest in continuous systems as compared to semi-continuous systems (Rs. 0.03 and 0.017/billion cells as against Rs. 0.082 and 0.037/billion cells)

Quasi-two-dimensional optomechanical crystals with a complete phononic bandgap

A fully planar two-dimensional optomechanical crystal formed in a silicon microchip is used to create a structure devoid of phonons in the GHz frequency range. A nanoscale photonic crystal cavity is placed inside the phononic bandgap crystal in order to probe the properties of the localized acoustic modes. By studying the trends in mechanical damping, mode density, and optomechanical coupling strength of the acoustic resonances over an array of structures with varying geometric properties, clear evidence of a complete phononic bandgap is shown.Comment: 9 pages, 7 figure

Dentigerous Cyst Associated with Ectopic Canine and a Supernumerary Tooth: A Rare Occurrence

Amongst the cysts of the jaw dentigerous cyst (DC) is one of the most prevalent types of odontogenic cysts, which is associated with the crown of an unerupted or developing tooth. DC is more commonly seen with mandibular  third molar and maxillary canine and rarely other teeth are involved. These cysts seldom associate with supernumerary teeth. The purpose of this article is to describe a case of large dentigerous cyst associated with supernumerary teeth and an ectopic canine, which is a rare presentation along with its management.Key words: Dentigerous cyst, ectopic teeth, supernumerary teet

Role of Imaging in Dental Implants

Dental implants have become an accepted form of permanent tooth replacement. Nearly all implants currently being placed are of the osseointegrated type. These typically consist of three parts: a fixture, an abutment and a screw or threaded rod. The fixture, usually composed of titanium, can be placed in either a surgically created site in the alveolar ridge or a fresh extraction socket. Diagnostic imaging can play an important role in evaluating patients with such implants. Useful imaging studies include plain panoramic radiography, computed tomography, and computer-reformatted cross-sectional, panoramic, and three-dimensional imaging. Advanced imaging studies can be used to determine the suitability of implant placement, appropriate sites for implant placement, the size of the implant that can be placed, and the need for preimplantation ridge surgery. Postoperatively, advanced imaging studies can show failure of an endosseous implant to osseointegrate, improper placement of an implant, and violation of important structures. This paper gives a brief insight into the various imaging modalities, which have been applied in implantology

Advanced Diagnostic Aids in Endodontics

Conventional radiographs used for the management of endodontic problems yield limited information because of the two-dimensional nature of images produced, geometric distortion and anatomical noise. This newer review paper seeks to clarify three-dimensional imaging techniques that have been suggested as adjuncts to conventional radiographs. These include tuned aperture computed tomography, magnetic resonance imaging, ultrasound, computed tomography and cone beam computed tomography (CBCT)