Design of Bistable Composite Laminates for Shape Morphing Applications

Composite materials, specifically Laminated Fibre Reinforced Polymers / Plastics (FRP), are versatile material systems which have become a part of everyday life. These are no longer considered “space age” materials, but are also being used in aircraft/military, automotive/transportation and construction/civil infrastructure applications. The major reasons behind these materials gaining prominence are that they are light weight, they have high strength to weight ratio and tailored properties. In the recent past, 35 years back, an entirely new research area in the field of composite materials had begun called “Bistable Composites”. These composites, as the name suggests, have two stable shapes and a snap through / snap back phenomenon between these two shapes, which makes them suitable materials for use in “Adaptive Structures”. Bistable composites are unsymmetric laminated FRPs that exhibit bistability because of the unsymmetric laminate stacking sequence about the middle surface. In this research, the possibility of obtaining desired shapes in both stable states of any given geometry is explored using Finite Element (FE) simulations and experimental validation. The methodology followed is as follows: the given geometry is tessellated and several iterations are carried out to find the combination of symmetric and unsymmetric laminates for which the desired shapes are achievable. To decide on the proper tessellation and carry out the iterations efficiently, two major topics are addressed initially. They are the behavior of individual unsymmetric laminates and the behavior of the combination of symmetric and unsymmetric laminates. In the individual unsymmetric laminates, the effects of geometry and fibre orientation on the snap through and snap back loads are studied, to identify the parameters that controls the critical load at which the shape changes. In the combination of symmetric and unsymmetric laminates, various standard geometries are split into smaller geometries, each of those are made into symmetric or unsymmetric laminates and different combinations of those symmetric and unsymmetric laminates are studied to find the various bistable shapes that are possible in each standard geometry. An experimental setup is built to measure the snap through and snap back loads of the individual rectangular unsymmetric laminates. The simulation results obtained are validated by fabricating those laminates and conducting experiments to confirm the data obtained numerically

The motion of bubbles inside drops in containerless processing

A theoretical model of thermocapillary bubble motion inside a drop, located in a space laboratory, due to an arbitrary axisymmetric temperature distribution on the drop surface was constructed. Typical results for the stream function and temperature fields as well as the migration velocity of the bubble were obtained in the quasistatic limit. The motion of bubbles in a rotating body of liquid was studied experimentally, and an approximate theoretical model was developed. Comparison of the experimental observations of the bubble trajectories and centering times with theoretical predictions lends qualified support to the theory

Rice endophytes and their potential applications

Endophytic microbial communities in crop plants are beginning to be explored. These microbes are either carried through seeds or establish colonization in the plants from soil based on chemotaxis of root exudates. Variability and diversity of endophytic bacteria and fungi have been observed in rice plants in different plant parts and growth stages. Genotypic variations are observed between Indica and Japonica. Pseudomonas, Bacillus, Streptomyces, Azospirillum, Azotobacter are some of the dominating genera of bacteria in internal tissues of rice plants. These endophytes provide benefits such as tolerance to abiotic stresses, defense against pest and diseases, nutrient solubilization and mobility. In addition, many metabolites are characterized from the endophytes that are useful in other branches of biotechnology including bioremediation. Complete characterization of microbiome of rice plants under various soil agro-climatic zones and understanding their population dynamics, co-occurrence and networking will help in identifying useful strains for developing new biofertilizers, plant growth promoting microbes and biopesticides

Deflection of mini implants from its intended path of placement on varying bone densities

Knowledge of bone density in maxilla and mandible will allow the clinician to plan the anchorage strategies and placement of implants with necessary precautions. The study aims to evaluate the deflection changes of titanium alloy self-drilling mini impla

(E)-3-(4-Methyl­phen­yl)-1-(1,3-thia­zol-2-yl)prop-2-en-1-one

In the title chalcone, C13H11NOS, derived from the condensation of p-tolualdehyde and 1-(1,3-thia­zol-2-yl)ethanone, the olefine group has a trans configuration. No classical hydrogen bonding is present in the crystal structure

Physical phenomena in containerless glass processing

Experiments were conducted on bubble migration in rotating liquid bodies contained in a sphere. Experiments were initiated on the migration of a drop in a slightly less dense continuous phase contained in a rotating sphere. A refined apparatus for the study of thermocapillar flow in a glass melt was built, and data were acquired on surface velocities in the melt. Similar data also were obtained from an ambient temperature fluid model. The data were analyzed and correlated with the aid of theory. Data were obtained on flow velocities in a pendant drop heated from above. The motion in this system was driven principally by thermocapillarity. An apparatus was designed for the study of volatilization from a glass melt

Contamination by PCDDs, PCDFs and coplanar PCBs in open dumping sites in Vietnam-levels, patterns and toxic implications

Joint Research on Environmental Science and Technology for the Eart

OVERVIEW OF ARSENIC CONTAMINATION IN GROUNDWATER AND HUMAN HEALTH RISK IN VIETNAM

Joint Research on Environmental Science and Technology for the Eart

Seasonal variation of atmospheric organochlorine pesticides and polybrominated diphenyl ethers in Parangipettai, Tamil Nadu, India:Implication for atmospheric transport

During 1990s, residues of several persistent organic pollutants (POPs) in different environmental matrices have been reported from a tropical coastal site, Parangipettai (PI), located along the bank of the Vellar River in Tamil Nadu. Hence to fill the existing data gap after the strict ban on several POPs, high volume air sampling was conducted in PI to study the variability of atmospheric pesticidal POPs and polybrominated diphenyl ethers (PBDEs) during summer, pre-monsoon and monsoon. Emission source regions were tracked by using five days back trajectory analysis. Derived range of air concentrations in pg/m3 were: DDTs; BDL - 1976; HCHs, 260–1135, HCB; 52–135, chlordanes; 36–135, endosulfans; 66–1013. ∑6PBDE ranged between 25 and 155 with highest concentration in summer followed by pre-monsoon and monsoon. Atmospheric DDT and HCH in PI has drastically reduced by several thousand folds from the past report thereby showing the strict ban on agricultural use of these compounds. During monsoon fresh source of o,p′‑DDT, trans‑chlordane and α‑endosulfan was evident. Usually higher level of endosulphan sulfate in PI seems to be likely affected by the air mass originating from a neighbouring state Kerela, where endosulfan has been extensively used for cashew plantations. Similarly in summer, the day showing the highest level of PBDEs, the sample was concurrently impacted by air parcel comprised of two major clusters, 1 (25%) and 2 (49%) that traversed through the metropolitan cities like Bangalore and Chennai. Dominance of BDE-99 over BDE-47 in Parangipettai is in line with the PBDE profile reported from Chennai city during the similar time frame. Average concentration of tetra and penta BDE congeners in summer samples were nearly 2–3 folds higher than pre-monsoon or monsoon. Given the fact that strong localised source for heavier BDE congeners are lacking in PI, regional atmospheric transport from the strong emission source regions in Chennai

Expression and production optimization of the cationic antimicrobial peptide : indolicidin by the recombinant E. coli C41 (DE3) clones

The cytoplasmic granules of bovine neutrophils naturally possess indolicidin - a promising cationic antimicrobial peptide as it displays inherent inhibitory activities against a broad type of microbial pathogens. In this study, a shake flask level production and expression optimizations of the indolicidin by the recombinant Escherichia coli C41 (DE3) clones (transformed with pET21a(+) plasmid carrying indolicidin gene) were carried out under standard conditions, as to determine the conditions required for maximal production. It was determined that a concentration of 1 mM of IPTG was effective, the 2×YT with salts and LB media at pH 7.5 with 3-6 h of incubation were required for maximal indolicidin expression