Synthesis and characterization of hindered‐phenol‐containing amine moieties as antioxidants for polypropylene copolymers

(4‐Ethylphenyl)‐3,5‐ditertiarybutyl‐4‐hydroxybenzylamine, 1‐phenyl‐4‐(3,5‐ditertiarybutyl‐4‐hydroxybenzyl)piperazine, and 1‐(3,5‐ditertiarybutyl‐4‐hydroxybenzyl)piperidine were synthesized and characterized, and their performance in polypropylene copolymer (PPCP) was tested by multiple extrusions in a Brabender plasticorder. The thermooxidative stability of PPCP was assessed by the measurement of oxidative induction time at 200 ± 1°C, and the thermal stability was assessed by observation of the change in the melt flow rate. A comparative study of the synthesized antioxidants with the commercially available antioxidant 2,6‐ditertiarybutyl‐4‐methylphenol was made. The presence of phenolic and amino groups influenced the performance of the antioxidants. The performance of the antioxidants influenced the thermal stability of the PPCP. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1097–1103, 2004     

Influence of linoleic acid,pH and HRT on anaerobic microbial populations and metabolic shifts in ASBRs during dark hydrogen fermentation of lignocellulosic sugars

In this study, controlling an anaerobic microbial community to increase the hydrogen (H₂) yield during the degradation of lignocelluosic sugars was accomplished by adding linoleic acid (LA) at low pH and reducing the hydraulic retention time (HRT) of an anaerobic sequencing batch reactor (ASBR). At pH 5.5 and a 1.7 d HRT, the maximum H₂ yield for LA treated cultures fed glucose or xylose reached 2.89 ± 0.18 mol mol⁻¹ and 1.94 ± 0.17 mol mol⁻¹, respectively. The major soluble metabolites at pH 5.5 with a 1.7 day HRT differed between the control and LA treated cultures. A metabolic shift toward H₂ production resulted in increased hydrogenase activity in both the xylose (13%) and glucose (34%) fed LA treated cultures relative to the controls. In addition, the Clostridia population and the H₂ yield were elevated in cultures treated with LA. A flux balance analysis for the LA treated cultures showed a reduction in homoacetogenic activity which was associated with reducing the Bacteriodes levels from 12% to 5% in the glucose fed cultures and 16% to 10% in the xylose fed cultures. Strategies for controlling the homoacetogens and optimal hydrogen production from glucose and xylose are proposed.     

Group II-VI semiconductor quantum dot heterojunction photodiode for mid wave infrared detection

In this article we report the development of 10×10 photodiode array by realizing heterojunction between mercury cadmium telluride (HgCdTe) quantum dot (diameter ~14 nm) and silicon responsive in mid wave infrared (MWIR) range (l=3—5 μm) at room temperature. Performance of this optical sensor has been evaluated experimentally and Detectivity of 1.6×108 cm /W has been achieved at spectral wavelength of 3.5 μm at 300 K. This work ascertains the compatibility of chemically synthesized HgCdTe quantum dots with commercially available direct injection type readout integrated circuits (ROIC) for the development of low cost large format MWIR focal plane array (FPA).     

Preparation,Sedimentation, and Agglomeration of Nanofluids

Research on nanofluids has increased significantly in the last decade due to the distinctive potential in many applications such as enhanced heat transfer processes, drug delivery systems, and membrane manufacturing processes. The study of dispersion behavior of nanoparticles in liquids is a topic of keen interest towards the preparation of stable nanofluids. A comprehensive review on the recent progress in preparation and stability of nanofluids is presented. Settling of nanoparticles is the only predicament towards preparation of stable nanofluids which takes place due to formation of agglomerates. The settling behavior of nanoparticles in nanofluids and techniques to stop agglomeration are described. Nanofluid preparation techniques, assessment method of stability, and methods to reduce agglomeration are discussed.