Organogenesis induction in rice callus by cyanobacterial extracellular product

Cyanobacteria or blue green algae are prokaryotic photosynthetic microorganism that produces a wide array of substances, including plant growth regulators. In the case of growth regulators, gibberellin, auxin, cytokinin, ethylene, abscisic acid and jasmonic acid have been detected in cyanobacteria. Many substances have been added to plant tissue culture media in order to promote plant regeneration. The present research communication gives a report of the study of the effect of extracellular products of Plectonema sp., isolated from paddy fields on regeneration of rice. The endosperm of three rice varieties, IR 50, ASD 16 and ADT 36, were used as explants. IR 50 showed earlier and good callus induction response in MS medium. For root induction, cyanobaterial extracellular product was added instead of 2,4-D. The result showed that the number of days taken for root initiation and root growth was quicker by adding the extracellular products. Interestingly, more proliferation of roots in cyanobaterial extracellular product treatments was also observed compared to 2,4-D which might due to the production of growth regulators like auxin(s). Tremendous growth of root length and volume in short period indicate that MS with cyanobaterial extracellular product may also be used for screening of rice genotypes for water stress condition.Keywords: Callus induction, cyanobacterial extracellular products, Plectonema sp., rice, root inductio

The effect of the orientation of cubical projectiles on the ballistic limit and failure mode of AA2024-T351 sheets

This paper presents the results of an investigation of the ballistic limits and failure modes of AA2024-T351 sheets impacted by cubical projectiles. The effect of cube orientation on the ballistic limit and failure modes was considered in detail. Three impact configurations were investigated. Configuration one, two and three considered face, edge or corner impacts correspondingly. The experimental results were complemented with finite element analysis results in order to explain the observations. The lowest ballistic limit (202 m/s) was observed when the cube edge impacted on the target. In the cube face impacts, the ballistic limit was higher (223 m/s), and the highest ballistic limit (254 m/s) was observed for the corner impact. Although the face impact did not have the lowest ballistic limit, this impact configuration resulted in the least amount of projectile energy loss for impacts above the ballistic limit. With the aid of finite element modelling, it was possible to develop a better understanding of the test results and explain that the observed differences in impact response were not just due to a difference in projectile frontal area, but also due to the combination of the localised deformation near the projectile impact point and the resulting global (dishing) deformation

A remote delivery tube with an integral Joule-Thompson valve for the helium liquefier

Remote delivery tubes (RDTs) in Collins and similar types of helium liquefiers interconnect the liquefier with the storage dewar. In these liquefiers the Joule-Thompson (J-T) valve is separately situated in the liquefier cryostat. Therefore there is a regime of J-T heating during the initial cool down of the liquefier, since there is a time lag in reaching the inversion temperature for the J-T valve. The note describes the design, fabrication, and testing of a RDT with an integral J-T valve. A demountable copper cold seal working at a pressure of 15 bar was successfully tested. The J-T valve seat made of Cu-Cr-Zr alloy provided excellent sealing with the stainless-steel valve tip at liquid-helium temperatures. The testing of this RDT with integral J-T showed substantial reduction in cool down time for the liquefier as well as better control of the dewar pressures

A preliminary study on the screening of emerging drug resistance among the caries pathogens isolated from carious dentine

Background: Dental caries being the commonest unmet public health problem indicates its need to urge the dentists to overcome this problem globally. Caries exhibit in different types and is found to be associated with co-aggregation property of microbial flora with other oral hygienic factors. In spite of the surgical removals, excavations and administration of antimicrobials for carious dentine, there seems to be repeated infection and chronic prevalence of caries. A complete understanding of microbial etiology and prevention of emerging drug-resistant strains will aid in the eradication of this chronic dentine problem condition from the oral cavity. Aim: This study is aimed to isolate the predominant bacterial pathogens associated with caries and to screen for the emergence of drug resistance among the isolated caries pathogens. Materials and Methods: Carious dentine specimens were collected from 75 endodontic patients and the samples were processed microbiologically to isolate the caries pathogens. Identification of the strains was done by standard biochemical characterization studies. Statistical analysis of the isolates was done by Pearson Chi-square test and Fisher′s exact test. The predominant isolates were subjected to antimicrobial sensitivity test using Kirby Bauer′s method. The results were recorded and analyzed for drug resistance. Results: Carious dentine samples yielded a high percentage of Lactobacillus sp., and Candida albicans from different type of caries. Among the study population, dentinal caries was the most predominant type affecting most males with other associated risk factors. Nearly 47.3% of the isolated Lactobacillus sp. and 55.5% of the yeast C. albicans were screened to show resistance against the antimicrobials used for the study. Conclusion: This study concludes by stating that Lactobacillus sp., and C. albicans are mostly involved in the caries etiology and show resistance to the commonest antimicrobial agent. This implicates the need for periodical antimicrobial susceptibility examination of the caries pathogens that will aid to prevent the emergence of resistance property among the dentinal pathogenic organisms