Electrochemistry of Zirconium Tetrachloride in the Ionic Liquid N‐Butyl‐N‐methylpyrrolidinium Bis(trifluoromethylsulfonyl)imide: Formation of Zr(III) and Exploitation of ZrCl4 as a Facile Ionic Liquid Drying Agent

The electrochemistry of zirconium tetrachloride in the ionic liquid N‐butyl‐N‐methylpyrrolidinium bis(trifluoromethylsulfonyl)imide has been studied, and the one electron reduction is proved by chronoamperometry. Furthermore, we report the application of ZrCl₄ as a facile and general ionic liquid drying agent for use in voltammetry.     

Design of Green-Emitting Salts from Substituted Pyridines: Understanding the Solid-State Photodimerization of trans-1,2-bis(4-pyridyl)ethylene

Polymorphic salts of trans-1,2-bis(4-pyridyl)ethylene (bpe), 2 [bpeH₂] ⋅ (SO₄)(2HSO₄) ( 1 ) and [bpeH₂] ⋅ 2HSO₄ ( 2 ) have been synthesized and their structures determined by X-ray crystallography. The Schmidt postulate predicts that neither of the salts will give rise to photodimerization so they can both potentially be applied as green light emitters. Despite the predictions, 1 undergoes a stereospecific solid-state photodimerization reaction with 100 % yield. This is due to UV induced combination of sliding and pedal-like movement of the pyridyl ring system that influences the alignment of C=C bonds. The sliding motion is restricted in 2 . Consequently, the green emission from 1 is completely quenched after photodimerization. It is evident that counter ions play a dominant role in dis- and enabling photodimerization; their degree of protonization and lattice placement are important solvent controlled design parameters towards crystal structures that can act as future light emitters.     

LCO flutter of cantilevered woven glass/epoxy laminate in subsonic flow

The paper presents a cantilevered composite wing, aeroelastic characteristics of idealized as a composite flat plate laminate. The composite laminate was made from woven glass fibers with epoxy matrix. The elastic and dynamic properties of the laminate were determined experimentally for aeroelastic calculations. Aeroelastic wind tunnel testing of the laminate was performed and the result showed that flutter, a dynamic instability occurred. The cantilevered laminate also displayed limit cycle amplitude, post-flutter oscillation. The experimental flutter velocity and frequency were verified by our computational analysis.     

Total synthesis of gabosines via an iron-catalyzed intramolecular tandem aldol process

Several gabosines, belonging to polyhydroxy-cyclohexenone and cyclohexanone class of natural products, are synthesized in various stereoforms using an intramolecular iron-catalyzed tandem aldol process. The reaction, which starts from vinylic pyranoses, is compatible with two different OH protecting groups (acetyl and benzyl). Further, like the Ferrier carbocyclisation, it is not sensitive to the stereochemistry of sugar molecules used as precursors: six different gabosine-type molecules have been prepared by this route starting from d-Glucose, d-Mannose, and d-Galactose derivatives.     

Preparation and investigation of nanostructured SnO2:Pd/ porous silicon/c-Si heterostructure solar cell

Journal of Solid State Electrochemistry - We have deposited pure SnO2 and SnO2:Pd nanostructure films on the quartz and porous silicon PSi substrates using chemical spray pyrolysis technique to...     

Laser control melting of alumina surfaces and thermal stress analysis

Laser gas assisted melting of alumina surface is carried out and temperature as well as stress fields developed in the irradiated region are predicted using the finite element method (FEM). An experiment is conducted resembling the simulation conditions. Optical and scanning electron microscope (SEM) are used to examine the morphological and the metallurgical changes in the laser treated region. The X-ray diffraction (XRD) technique is used to determine the residual stress developed in the irradiated region. It is found that the residual stress predicted agreed with the measurement result. High heating and cooling rates result in high von Mises stress levels in the surface region.     

Neutrally expandable models of arithmetic

A subset of a model of is called neutral if it does not change the relation. A model with undefinable neutral classes is called neutrally expandable. We study the existence and non‐existence of neutral sets in various models of . We show that cofinal extensions of prime models are neutrally expandable, and ω₁‐like neutrally expandable models exist, while no recursively saturated model is neutrally expandable. We also show that neutrality is not a first‐order property. In the last section, we study a local version of neutral expandability.     

Preparation and characterization of a new sol–gel hybrid based tetraethoxysilane-polydimethylsiloxane as a stir bar extraction sorbent materials

A new tetraethoxysilane-polydimethylsiloxane (TEOS-PDMS) for use as sorbent of stir bar sorptive extraction (SBSE) towards two selected organophosphorus pesticides (OPPs) namely chlorpyrifos and malathion was successfully synthesized through sol–gel technology. Four different molar ratios of TEOS:PDMS (1:1, 2:1, 3:1 and 4:1) sol solutions were prepared and dipped coated onto the surface of a glass-encased stir bar. Extraction efficiency of the prepared coatings towards the two selected OPPs were compared. A number of factors have been found to greatly affect the characteristics and properties of a particular sol–gel coating. Hence, in this study, several sol–gel coating conditions have been optimized using the optimized molar ratio 3:1 TEOS:PDMS to obtain the best coating as the stationary phase for SBSE. The raw OH-TPDMS and TEOS were characterized using Fourier Transform Infrared Spectroscopy (FT-IR) and compared with spectra of the four different molar ratios of TEOS:PDMS. The FT-IR spectrum of TEOS:PDMS showed the co-polymerization between PDMS and hydrolyzed TEOS molecules demonstrating the formation of the hybrid network in the sol–gel hybrid material. Surface morphology of hybrid sol–gel TEOS-PDMS with optimized molar ratio of 3:1 TEOS:PDMS were examined using FE-SEM. The surface of the sol–gel coating seems to be rough and homogeneous. The more rough structure formed by the 3:1 molar ratio TEOS:PDMS provides enhanced surface area which in turn improved sample capacity or adsorption process.     

Variation of <Superscript>231</Superscript>Pa, <Superscript>230</Superscript>Th and <Superscript>231</Superscript>Pa<Subscript>ex</Subscript>/<Superscript>230</Superscript>Th<Subscript>ex</Subscript> in surface sediments of the Sabah–Sarawak coastal waters

Protactinium and thorium activities were measured in eight surface sediment taken in 2004 to determine effectiveness scavenging of ²³¹Pa at Sabah–Sarawak coastal waters. The result found that activity ratios of ²³¹Pa_ex/²³⁰Th_ex were ranged from 0.07 to 0.13 at all sampling stations. The high ²³¹Pa_ex/²³⁰Th_ex activity ratio than the production ratio of 0.093 in seawater at station SR 01, SR 02, SR 04, SB 02 and SB 05, revealed that ²³¹Pa is effectively removed from the water column into the sediment in comparison with ²³⁰Th at those stations. Low percentage of ²³⁰Th_ex (90–95%) in comparison with ²³¹Pa_ex at all stations can be attributed to less efficiently scavenged of ²³⁰Th onto particles prior deposited at the marine sediment bed.