A genetic algorithm-based energy-aware multi-hop clustering scheme for heterogeneous wireless sensor networks.

Background: The energy-constrained heterogeneous nodes are the most challenging wireless sensor networks (WSNs) for developing energy-aware clustering schemes. Although various clustering approaches are proven to minimise energy consumption and delay and extend the network lifetime by selecting optimum cluster heads (CHs), it is still a crucial challenge. Methods: This article proposes a genetic algorithm-based energy-aware multi-hop clustering (GA-EMC) scheme for heterogeneous WSNs (HWSNs). In HWSNs, all the nodes have varying initial energy and typically have an energy consumption restriction. A genetic algorithm determines the optimal CHs and their positions in the network. The fitness of chromosomes is calculated in terms of distance, optimal CHs, and the node's residual energy. Multi-hop communication improves energy efficiency in HWSNs. The areas near the sink are deployed with more supernodes far away from the sink to solve the hot spot problem in WSNs near the sink node. Results: Simulation results proclaim that the GA-EMC scheme achieves a more extended network lifetime network stability and minimises delay than existing approaches in heterogeneous nature.

Shear Bond Strength of Repaired Composites Using Surface Treatments and Repair Materials: An In vitro Study.

BACKGROUND: Enhancement of bond strength between new and old composite usually requires increased surface roughness of old composite to promote mechanical interlocking and subsequent coating with bonding agents to improve surface wetting and chemical bonding. So this study was carried out to evaluate and compare the effects of different surface treatments and repair materials on the shear bond strength (SBS) of composite repairs The mode of failure of repaired composites whether cohesive or adhesive was also evaluated. MATERIALS AND METHODS: The substrates for 60 composite specimens were fabricated and aged with water treatment and subjected to various surface treatments. The surface treatment regimens used in the study were: No surface treatment, abraded with diamond bur, air abraded (sandblasted) with 50 µ aluminum oxide particles. Specimens were then repaired with fresh composite using either Clearfil(™) repair or all-bond two adhesive systems. Specimens were water stored, thermocycled and tested for SBS using universal testing machine. Fractured specimens were then examined under stereomicroscope to determine the mode of failure. RESULTS: It was clearly showed that surface roughening of the aged composite substrate with air abrasion, followed by the application of Clearfil(™) repair adhesive system (Group IIIa) yielded the highest repair bond strength (32.3 ± 2.2 MPa). CONCLUSION: Surface treatment with air abrasion followed by bonding with Clearfil(™) repair adhesive system can be attempted clinically for the repair of composite restorations.

Chronic inflammatory gingival overgrowths: laser gingivectomy & gingivoplasty.

It is quite common to note chronic inflammatory Gingival overgrowths during and/or post orthodontic treatment. Sometimes the overgrowths may even potentially complicate and/or interrupt orthodontic treatment. With the introduction of soft tissue lasers these problems can now be addressed more easily. Amongst many LASERS now available in Dentistry DIODE LASERS seem to be most ideal for orthodontic soft tissue applications. As newer treatments herald into minimally invasive techniques, DIODE LASERS are becoming more promising both in patient satisfaction and dentist satisfaction. How to cite this article: Shankar BS, Ramadevi T, Neetha M S, Reddy P S K, Saritha G, Reddy J M. Chronic Inflammatory Gingival Overgrowths: Laser Gingivectomy & Gingivoplasty. J Int Oral Health 2013; 5(1):83-87.

An evaluation of shear bond strength of self-etch adhesive on pre-etched enamel: an in vitro study.

AIM: To determine the shear bond strength of self-etch adhesive G-bond on pre-etched enamel. MATERIALS AND METHODS: Thirty caries free human mandibular premolars extracted for orthodontic purpose were used for the study. Occlusal surfaces of all the teeth were flattened with diamond bur and a silicon carbide paper was used for surface smoothening. The thirty samples were randomly grouped into three groups. Three different etch systems were used for the composite build up: group 1 (G-bond self-etch adhesive system), group 2 (G-bond) and group 3 (Adper single bond). Light cured was applied for 10 seconds with a LED unit for composite buildup on the occlusal surface of each tooth with 8 millimeters (mm) in diameter and 3 mm in thickness. The specimens in each group were tested in shear mode using a knife-edge testing apparatus in a universal testing machine across head speed of 1 mm/ minute. Shear bond strength values in Mpa were calculated from the peak load at failure divided by the specimen surface area. The mean shear bond strength of all the groups were calculated and statistical analysis was carried out using one-way Analysis of Variance (ANOVA). RESULTS: The mean bond strength of group 1 is 15.5 Mpa, group 2 is 19.5 Mpa and group 3 is 20.1 Mpa. Statistical analysis was carried out between the groups using one-way ANOVA. Group 1 showed statistically significant lower bond strength when compared to groups 2 and 3. No statistical significant difference between groups 2 and 3 (p < 0.05). CONCLUSION: Self-etch adhesive G-bond showed increase in shear bond strength on pre-etched enamel.

Study of the soil isolates for antimicrobial activity.

During the process of screening for a potent antimicrobial compound, a new strain was isolated from the soil sample of Thalaikunda village in Ooty, Tamil Nadu. That organism was name as NK(2). It was found to be antagonistic to both bacterial and fungal test organisms. Production of antibiotic was more in a newly formulated broth. Antibiotic production reached maximum at the end of the 70 h of fermentation by stirred flask culture. The antimicrobial compound was extracted in n-butanol, ethyl acetate and methanol. Antimicrobial compound, which was produced by the soil isolate NK(2) did not showed cytotoxic activity on Vero cell lines.

Suitability of measurement of swirling as a marker of platelet shape change in concentrates stored for transfusion.

Platelet discoid shape is known to correlate with in vivo viability after transfusion. Measurement of shape change requires invasive sampling and laborious assays, which is difficult to perform in a blood transfusion center as a routine test for quality control of stored platelets. The objective of this study was to establish suitability of swirling assessment in stored platelet suspension as a routine test for quality check, by comparing platelet shape change measurement carried out in parallel. The study was done in two types of bags obtained from different manufactures (Groups 1 and 2). Platelet concentrates (PC) were stored for 120 h and samples drawn at 24-h intervals, optical analysis at 540 nm was carried out to quantify shape change in response to an agonist adenosine diphosphate (ADP). The same bags were subjected to swirling assessment, by two blood bank personnel independently and graded as positive (+, ++, +++) or as negative, based on the silky appearance of the suspension. Swirling negative platelets were prepared by storing platelets at 4 degrees C for 24 h and were compared with swirling positive platelets. Other parameters studied in the samples drawn at 24-h intervals were platelet count, mean platelet volume, and blood gases. Swirling assessment results correlated well with shape change measurement at each study period with a P value significant at 0.02 and 0.04 for group 1 and 2 bags, respectively. In the negative swirling controls, extent of shape change was lower than the extent in test bags, showing reduced capacity to respond to ADP at 4 degrees C. The results of the study indicate that by simple swirling measurements, stored PC can be monitored for loss of discoid shape before they are transfused. Gas tension and pH were with in permissible limits. Therefore, inspection of swirling can be a reliable method of quality control as it correlates with platelet function. The platelets that retain the discoid shape in vitro at the time of transfusion are expected to be functional in vivo.

Antimicrobial potential of two different Hypericum species available in India.

The antimicrobial activity of extracts of the leaves and stems of two different varieties of Hypericum was evaluated by the disc diffusion method. Petroleum ether, acetone, chloroform and methanol extracts of Hypericum mysorense and Hypericum patulum stems and leaves were investigated for their antimicrobial activity against six different strains of bacteria and fungi by the zone of inhibition method (ZIM). The results showed that both the stem and leaf extracts of both species have a very broad spectrum of antibacterial activity. The petroleum ether and acetone extract of the leaves and stems of H. mysorense did not show antifungal effects against any of the six fungal organisms tested but other extracts showed a potential antifungal effect which was comparable to that of griseofulvin, the standard antifungal agent. Thus these results demonstrate that the leaf and stem extracts of both the Hypericum species have a very broad spectrum of activity and suggest that they may be useful in the treatment of various microbial infections.

Antibacterial spectrum of Hypericum hookerianum.

The antibacterial activity of the chloroform, acetone and methanol extracts of Hypericum hookerianum leaves and stems was evaluated. All extracts showed antibacterial activity against six different gram-positive and gram-negative bacteria, the methanol extracts exhibiting the maximum inhibitory activity at 400 microg/ml.