Intensity tunable optical limiting behaviour of an organic material 2-aminopyridinium succinate succinic acid single crystal

Journal of Materials Science: Materials in Electronics - A mixed solution of 2-aminopyridine and succinic acid, with a 1:1 molar ratio, was kept at room temperature to develop a 2-aminopridinium...     

Irradiation Target Cooling Using Circular/Slot Air Jet

To study the effect of irradiation on materials, sample coupons are irradiated in cyclotron facilities. During the irradiation process, these samples produce significant heat. This heat needs to be continuously removed from the samples in order to avoid melting of the samples as well as to keep the samples at a particular temperature during irradiation. The area available for heat transfer is limited due to small size of the samples. To increase the heat transfer rate, jet cooling is used as it provides large heat transfer co-efficient. To understand the heat transfer characteristics of jet cooling under these conditions, experiments have been carried out. Two inclined jets hitting on both sides of the target plate give maximum cooling and uniform temperature distribution. This paper gives the details of the numerical and experimental studies carried out and the discussions about the results obtained.     

Growth and characterization of metal ions and dyes doped KDP single crystals for laser applications

The organic dyes (Amaranth, Rhodamine B and Methyl Orange) are doped in Potassium Dihydrogen Phosphate crystals. Influences of supersaturation and dye concentration in the solution, on the color and crystal habit of Potassium Dihydrogen Phosphate, were observed. Amaranth in the solution at low super saturation and high dye concentration colored the pyramidal section (1 0 1) of the crystals. The highly super saturated solutions produce entirely colored crystals. Dyes doped Potassium Dihydrogen Phosphate crystals were also grown by solution growth technique. The concentration of dopants in the mother solution was varied from 0.1 to 10 mol%. The studies on pure and doped Potassium Dihydrogen Phosphate crystals clearly indicate the effect of dopants on the crystal structure, in the absorption of IR frequencies and the non-linear optical property. The frequencies with their relative intensities are obtained in Fourier Transform-Infrared spectra of pure and doped Potassium Dihydrogen Phosphate. The very weak bands for dopants indicate its presence in low concentration. The absence of even such a weak band in the case of Potassium Dihydrogen Phosphate doped with Amaranth indicates the strong interaction with O-H groups. The calculated IR frequency 3333 cm⁻¹ for O-H stretching was in close agreement with the experimentally obtained one for pure Potassium Dihydrogen Phosphate at 3340 cm⁻¹.The doped crystals show good second harmonic generation efficiency. The dopants increase the hardness value of the material, which also depends on the concentration of the dopants. Dye doping improves the Nonlinear Optical properties of the grown crystals. Results of the growth kinetics of Potassium Dihydrogen Phosphate crystals in the presence of impurities are also discussed.     

Development and differentiation of the anuran auditory brainstem during metamorphosis: an acetylcholinesterase histochemical study

The time course of cell differentiation and the presence of histochemically defined areas in brainstem auditory nuclei were examined in developing bullfrogs, Rana catesbeiana, using cresyl violet staining and acetylcholinesterase (AChE) histochemistry. In the medulla, the dorsolateral nucleus (DLN) can be seen as a distinct structure in its adult location only at Gosner stage 40 and beyond. The majority of cells in the DLN are not fully differentiated until late metamorphic climax (stages 45-46) and early postmetamorphosis. The more ventral vestibular nucleus differentiates earlier (stage 37) than the DLN. Adult-like organization of auditory nuclei in the torus semicircularis (TS) of the midbrain cannot be reliably discerned until metamorphic climax stages. Cellular masses in the brainstem reveal AChE from the earliest stage examined (stage 27) but the intensity of staining differs among cell groups. Staining intensity in the DLN is at a peak in recently metamorphosed froglets. The time course of cell differentiation in the DLN precedes slightly or is coincident with the increased, transient presence of AChE. Staining of the superior olive stabilizes at a moderate level in early postmetamorphic stages. Ventral regions of the principal nucleus in the TS stain more intensely than dorsal regions beginning at stage 40. This dorsal-ventral gradient in staining persists in adult stages. There is a transient decline in staining of the laminar nucleus in metamorphic climax stages. Staining intensity in the magnocellular nucleus peaks during stages 40-46 and in early postmetamorphic froglets and then declines in adults, paralleling the pattern seen in the DLN. These data suggest that metamorphic climax and early froglet periods are an important developmental window for major differentiation and maturational events in the auditory brainstem.     

Synthesis and characterization of Zr4+, La3+ and Ce3+ doped mesoporous TiO2: evaluation of their photocatalytic activity

Sol-gel method was used to synthesize Zr(4+), La(3+) and Ce(3+) doped mesoporous TiO(2) materials with different weight percentage (0.5, 1.0, 2.0 and 3.0 wt%) using triblock copolymer as the structure directing template in ethanol/water medium. Characterization revealed the isomorphic substitution of Zr(4+) ion into the lattice of TiO(2), and surface binding nature of La(3+) and Ce(3+) ions on mesoporous TiO(2). Microscopic examination confirmed the surface adsorption of foreign ion which could alter the particle morphology. The size of the particles was less than 20 nm. Photocatalytic activity of metal ions doped mesoporous TiO(2) was evaluated using aqueous alachlor as a model pollutant. It was found that 1 wt% Ce(3+) doped mesoporous TiO(2) exhibited higher activity than pure and other metal ions doped mesoporous TiO(2). The change of oxidation state of Ce(3+) is suggested to be the cause for enhanced photocatalytic activity.     

TiN and TiCN Coated Stainless Steel 316 Ultrosonic Cavitation Probe for High Temperature Application

Silicon - Ultrasonic Cavitation Probe Assisted method in Stir Casting is used to produce metal matrix nano-composites (MMNCs) in bulk quantity with uniform distribution of nano particles. The...     

Exploring Ag-doped Mullite as High Dielectric and Antimicrobial Reinforcement with Polybenzoxazine Matrix

The present work describes the development of high k dielectric aluminosilicate and its application as reinforcement with polybenzoxazine matrix to achieve high dielectric and antimicrobial nanocomposite. Initially, dielectric constant value of mullite was found to increase with respect to the percentage of Ag in mullite lattices and reached a maximum of 14.9, when doped with 5?mol%. Data from antimicrobial assay also suggest that, the zone of inhibition expands with respect to embedding silver, and thus 10?mol% of Ag-doped mullite exhibiting the highest antimicrobial property. Since, 3?mol% Ag-doped mullite hold better dielectric, various weight percentages of the same (MA₃) were embedded with polybenzoxazine matrices after its surface modification. Among the resulted nanocomposite, 1.5% of glycidyl-functionalized MA₃/polybenzoxazine not only showed remarkable enhancement in their thermal, dielectric, electrical conductivity but also exhibited a zone of inhibition of 11 and 12?mm against Escherichia coli and Pseudomonas aeruginosa, respectively. The enhanced thermal, dielectric, and antimicrobial properties will make this material as a suitable candidate in printed circuit board application in particularly for cold weather climatic conditions.     

Studies on the Sorption of Palladium using Cross‐Linked Poly (4‐Vinylpyridine‐Divinylbenzene) Resins in Nitric Acid Medium

Various cross‐linked (4, 8, and 12%) gel‐type weak‐base poly(4‐vinylpyridine) (PVP) resins were studied for palladium recovery from nitric acid medium. The sorption of palladium was found to decrease with an increase in cross‐linkage of the resin. 8 and 12% PVP resins exhibited maximum D _Pd(II) values at 2–6 M HNO₃, whereas 4% PVP resin showed maximum D _Pd(II) values at lower acidities (0.1 M HNO₃). FT‐IR, SEM, and XPS techniques were used for the characterization of palladium‐loaded resins. Detailed studies were carried out with the resin of modest cross‐linkage i.e., 8% PVP resin. The sorption isotherm studies revealed that the maximum palladium loading approaches the theoretical capacity of the resin, presuming the sorption of palladium as divalent anion at 4 M HNO₃. The pseudo‐second order kinetics model yielded the best fit for the experimental data of sorption kinetics. An increase in temperature accelerates the rate of palladium extraction and also the addition of chloride ions increases the palladium uptake. Column studies were performed using 4 and 8% PVP resins in 2 and 4 M nitric acid concentrations. The loaded palladium could be eluted efficiently with acidic thiourea solution.     

Streamlined life cycle assessment of residue utilization options in <Emphasis Type="Italic">Tongkat Ali </Emphasis>(<Emphasis Type="Italic">Eurycoma longifolia</Emphasis>) water extract manufacturing process

Life cycle assessment (LCA) is often used to compare alternative process options in terms of their overall impact on the environment to easily identify the most environmentally friendly alternative. In this work, a streamlined LCA study was conducted to assess three different residue utilization schemes for Tongkat Ali (Eurycoma longifolia) extract production. The case study was firstly simulated using a batch process simulation software. The results of mass and energy balances obtained from the simulation software were then subjected to life cycle analysis. By evaluating the different schemes for using the fibrous residue from the extraction process, the potential for environmental process improvement was identified. Overall, use of the residue as process fuel was found to be the most environmentally friendly option. It produces the least emissions and reduces resource usage per unit of product than the other options evaluated.