Use of kinetic plots for relative assessment of reactor throughput and energy consumption

The progress of high temperature processes is generally described in terms of variation of the degree of conversion () with time (t). The present paper outlines a procedure for making use of-t plots for comparative assessment of productivity and energy requirements for a test system with respect to a reference, on the basis of some simplifying assumptions. It is assumed that the throughput is inversely proportional to reaction time as in the case of batch reactors and plug flow reactors. It is also assumed that the energy requirement is a simple function of process temperature. The principles outlined is illustrated with reference to some laboratory data for reduction of iron oxide by coal.The authors wish to thank Prof. P. R. Rao, Director National Metallurgical Laboratory, Jamshedpur, India, for providing facilities for experimental work and for according permission to publish this work.     

Polymerization in lyotropic liquid crystals. I. Change of structure during polymerization

Polymerization was made at 60°C in a lyotropic liquid crystal of sodium undecenoate and water. The liquid crystalline structure prior to polymerization was identified by optical microscopy and low-angle x-ray diffraction as an array of hexagonal closely packed cylinders with the hydrophobic part of the soap in the center of the cylinders. During polymerization the structure became isotropic at 60°C. Cooling to 20°C transformed the structure to a lamellar liquid crystal–a reversible transition. The structure of the lamellar phase was interpreted as a polyethylene backbone from which deformed decanoate chains reached toward the aqueous layer. Molecular models showed the model to accept head-tail, head-head, and tail-tail configurations in cis and trans conformations with the exception of the cis tail-tail configuration.     

Antioxidant enzymes activity in subcellular fraction of freshwater prawnsM. malcolmsonii andM. lamarrei lamarrei

Subcellular distribution of Superoxide dismutase (SOD), catalase (CAT), selenium (SC) dependent glutathione peroxidase, and Se-independent glutathione peroxidase (GSH-Px) activities were detected in different tissues (hepatopancreas, muscle, and gill) of freshwater prawnsMacrobrachium malcolmsonii andMacrobrahium lamarrei lamarrei. CAT and SOD were found almost equally between the mitochondrial and cytosolic fraction. Both Se-dependent and Se-independent GSH-Px activities were mainly found in cytosolic fraction.     

New environmentally friendly solvent free synthesis of dihydropyrimidinones catalysed by N-butyl-N,N-dimethyl-α-phenylethylammonium bromide

N-Butyl-N,N-dimethyl-α-phenylethylammonium bromide catalyzes efficiently the three component condensation reaction of an aromatic aldehyde, a β-keto ester and urea/thiourea under solvent free conditions at 100°C to afford the corresponding dihydropyrimidinone in high yield.     

A gamma-spectrometric method for the determination of plutonium isotope ratios

A gamma-spectrometric method using an intrinsic high resolution germanium detector has been developed for the determination of isotope ratios of plutonium from samples in solution form. The method is based on the assay of low energy gamma-rays of²³⁸Pu,²³⁹Pu,²⁴⁰Pu and²⁴¹Pu and does not require the use of branching intensities or the knowledge of detection efficiencies for different gamma rays. Since low energy gamma-rays are used, the effect of²⁴¹Am has also been studied. It is found that results are not affected up to 0.5 wt% of²⁴¹Am in plutonium samples. An accuracy of 3% is achievable in the determination of²⁴⁰Pu/²³⁹Pu and²⁴¹Pu/²³⁹Pu atom ratios as demonstrated by carrying out measurements on isotopic standards of plutonium.     

New copper (II) complexes of tridentate dibasic ONO donor ligands derived from salicylaldehyde or substituted salicylaldehydes ando-hydroxybenzylamine

Summary Copper(II) complexes with the Schiff bases derived from Salicylaldehyde and its 5-chloro-, 5-bromo-, 5-nitro-, 3-ethoxy- and 3,5-dichloro derivatives, or from 2-hydroxy-1-naphthaldehyde ando-hydroxybenzylamine, have been synthesized and characterized on the basis of elemental analysis, i.r. and electronic spectra and magnetic susceptibility measurements. The Schiff bases behave as tridentate dibasic O, N and O donor ligands and form complexes with 11 metal: ligand stoichiometry which exhibit subnormal magnetic moments ( _eff=0.88–0.98 B.M.) and are involved in strong antifer-romagnetic exchange (–J=482–525 cm^–1). The complexes exhibit a d-d band atca. 1600 cm^–1. A dimeric structure with aminophenolic oxygen atoms as the bridging atoms is proposed on the basis of i.r. and magnetic data.     

HPLC separation of hydrogenated derivatives of buckminsterfullerene

Summary The effect of composition and flow rate of the mobile phase on the HPLC separation of hydrogenated buckminsterfullerene (C₆₀H_n n=2–38) was investigated on BuckySep column. Toluene was used as the basic solvent and hexane, heptane, cyclohexane, THF, acetonitrile, acetone, ethanol and 2-propanol as co-solvents. The fraction of co-solvents was varied 10–80%, and the flow rate 1–0.1 mL min⁻¹. Toluene-acetonitrile 65∶35 and toluene-acetone 50∶50 provided the best separation. Under the best conditions complete separation of C₆₀H₂ and almost complete separation of the four most abundant isomers of C₆₀H₄ were achieved. Separation of derivatives with higher hydrogen content was very poor. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997     

The effects of gamma irradiation on the microbiological, physical and sensory qualities of diced tomatoes

Diced Roma tomatoes were treated with gamma irradiation and evaluated for changes in microbial, physical, chemical and sensory properties. Dosages for Trial 1 were 0.0, 0.39, 0.56 and 1.82 kGy and in Trial 2, 0.0, 0.50, 1.24 and 3.70 kGy. Irradiation at 3.70 kGy resulted in no aerobic populations through day 12 and significantly fewer colonies through day 15 whereas yeast and mold populations experienced a 2 log reduction through day 12. Color, titratable acidity, and °Brix were not significantly affected by irradiation. Tissue firmness decreased with increasing dose but not with storage time. Treatment with 3.7 kGy decreased firmness by 50% and 20% with 0.5 kGy, however, the reduced firmness induced by 0.50 kGy was undetected by a 9 member trained sensory panel. A significant (p0.05) inverse correlation between changes in texture and water-soluble pectin (WSP) was determined while total pectin remained relatively constant and oxalate soluble pectin content decreased slightly with irradiation dose. The significant inverse correlation between the loss of firmness and WSP indicates that the changes in WSP play an important role in the tissue softening of tomatoes, This study indicates that irradiation at 0.5 kGy can reduce microbial counts substantially to improve microbial shelf life without adverse effects on sensory qualities.