Extraction of Neptunium (IV) Ions into 30% Tri‐Butyl Phosphate from Nitric Acid

The distribution of Np(IV) between 0.08–4.5 M HNO_3(aq,eqm) and ～30% tributyl phosphate has been modelled, accounting for the formation of 1:1 and 1:2 nitrate complexes and Np(IV) hydrolysis in the aqueous phase and the extraction of Np(NO₃)₄(TBP)₂ into TBP. The potential formation and extraction of NpOH(NO₃)₃(TBP)₂ and Np(NO₃)₄(TBP)₂.HNO₃ species, including spectroscopic evidence, and oxidations of Np(IV) to Np(V) and Np(VI) in the solvent phase have also been considered. The model highlights some key gaps in the available thermodynamic data.     

TEMPERATURE,DISTRIBUTIONS AND HEAT TRANSFER DURING THE DRYING OF LUMBER

ABSTRACT

This paper describes techniques that have been developed for accurately measuring the surface temperature of drying lumber using a radiation thermometer, and interior temperatures at various depths using 30 gauge thermocouples. Methods for calculating heat transfer coefficients during the drying of lumber are also described. Experimental results, showing surface and interior temperatures, and moisture content, as functions of drying time are presented.     

Injection molding: The effect of fill time on properties

The effect of fill time on the mechanical properties, surface appearance, and part dimensions of several polymers was determined. Two crystalline materials, polypropylene and nylon 6,6, and an amorphous material, acrylonitrile-butadiene-styrene (ABS), were used. In addition, the effect of the presence of glass fibers was examined using glass fiber reinforced nylon 6,6. The fill time was varied from 0.8 to 20 sec which included both the viscous flow controlled region (short fill times) where laboratory samples are ordinarily molded and the heat transfer controlled region (long fill times) where production parts arc commonly molded. No large variations in tensile properties were observed for polypropylene or nylon, but a 10 percent increase in peak tensile stress and strain for ABS did indicate that molecular orientation increased with increasing fill time. However, significant differences did occur in the properties of glass reinforced nylon. Peak tensile stress increased 15 percent and flexural strength decreased 10 percent as the fill time was increased. Although no change in the flexural modulus was observed, the scatter in the modulus decreased with increasing fill time. These property variations can be attributed to differences in the glass fiber orientation of the skin and core regions of the part. The measurement of molded tensile bar dimensions indicated there was little effect of fill time on the shrinkage of the various polymers except for shrinkage in the length direction for polypropylene. The shrinkage increased from 13 to 15.4 mm/m over the fill time range, a great enough difference to affect the fit of large parts. The most dramatic change with fill time was the surface appearance of the glass reinforced nylon. The surface of samples molded at short fill times had a dark uniform color and smooth appearance while samples molded at long fill times had a lighter color and a porous surface. This surface porosity is due to crystallization prior to complete pressurization of the mold. Therefore, in addition to affecting surface appearance, other surface related properties such as aging and the ability to plate plastic parts could also be affected.     

Multiple cool flames in static, unstirred reactors under reduced-gravity and terrestrial conditions

Multiple cool flames have been observed experimentally in a static, unstirred reactor at reduced gravity in an equimolar n-butane-oxygen premixture diluted with helium. These are the first observations of sustained cool flame oscillations in a static reactor when transport is governed by diffusive fluxes of heat and species. To date, only single cool flames have been reported at reduced gravity, while oscillatory cool flames have long been observed in static reactors at terrestrial conditions. The results suggest that enhanced conduction heat transfer can provide the required heat loss to sustain cool flame oscillations.     

Hydroliquefaction of Wyodak coal using bottoms recycle

Wyodak coal has been liquefied using recycle solvents consisting of blends of Wyodak coal-derived distillates and SRC or SRC oils, asphaltenes and oils plus asphaltenes. Whilst the quality of the distillate portion of the bottoms recycle is maintained by hydrogenation and distillation in the Exxon Donor Solvent (EDS) process, no reported efforts have been made to hydrogenate the nondistillable portion of the EDS bottoms recycle solvent nor the bottoms recycle solvent in the SRC-II process. As hydrogenation of the distillate portion of the recycle solvent in the EDS process increased Wyodak coal distillate yields, this study was initiated to determine whether hydrogenation of the nondistillable portions of Wyodak coal-derived bottoms recycle solvent would show similar beneficial effects. Results suggest that distillable liquid yields in the range of 55–60 wt% of dry Wyodak coal can be obtained using mildly hydrogenated SRC or SRC oils plus asphaltenes as a bottoms recycle solvent component. This result can be compared to distillable liquid yields of 40 wt% of dry, Wyodak coal obtained from the EDS process using bottoms recycle. Further, the unhydrogenated, SRC-derived oil and asphaltene portions of the recycle solvent also appear to be effective solvent components. However, the most effective solvents were obtained using hydrogenated SRC or SRC-derived oils plus asphaltenes.     

Regulation of the metabolism of linoleic acid to arachidonic acid in rat hepatocytes

When 5×10⁶ hepatocytes were incubated for 40 min with from 0.15 to 0.60 mM [1-¹⁴C]linoleic acid, [1-¹⁴C]6,9,12-octadecatrienoic acid, or [1-¹⁴C]8,11,14-eicosatrienoic acid, there was a concentration-dependent acylation of radioactive metabolites into both triglycerides and phospholipids. When the concentration of either [1-¹⁴C]linoleic acid or [1-¹⁴C]8,11,14-eicosatrienoic acid exceeded 0.3 mM, there was no further increase in the metabolism of either fatty acid to other (n−6) metabolites. When the concentration of [1-¹⁴C]6,9,12-octadecatrienoic acid exceeded 0.15 mM, there was an apparent substrate-induced inhibition in its metabolism to 8,11,14-eicosatrienoic acid. With all three substrates (0.3 mM), there was time-dependent metabolism to other (n−6) acids. Cells then were incubated simultaneously with 0.3 mM [1-¹⁴C]linoleic acid along with 0.15 to 0.45 mM 6,9,12-octadecatrienoic acid or 8,11,14-eicosatrienoic acid. These exogenous nonradioactive (n−6) acids suppressed but did not abolish the conversion of [1-¹⁴C]linoleate to radioactive arachidonate. These findings suggest that some linoleate is converted to arachidonate without intracellular mixing of 6,8,12-octadecatrienoic or 8,11,14-eicosatrienoic acids. This hypothesis is supported by the finding that exogenous linoleate did not markedly affect the metabolism of [1-¹⁴C]6,9,12-octadecatrienoic or [1-¹⁴C]8,11,14-eicosatrienoic acid by microsomal chain elongating or desaturating enzymes.     

Size analysis of single fullerene molecules by electron microscopy

Individual fullerene molecules were observed and sized using high resolution transmission electron microscopy. Fullerene C₆₀ molecules were tethered by chemical bonding to carbon black particles to facilitate HRTEM imaging and sizing of known fullerenes. HRTEM analysis of soot samples from a fullerene-forming flame revealed the presence of a range of fullerenes from C₃₆ to C₁₇₆ and larger fullerene-like structures. The observation of fullerenes smaller than C₆₀ is noteworthy in that such structures necessarily contain adjacent pentagons and hence are strained and expected to have interesting reactivity that may be useful in certain applications. HRTEM can be used to detect and size fullerenes in samples containing fullerenes but not in sufficient quantity, or not sufficiently removable, to be detectable by chemical analysis.     

Neonatal polyunsaturated fatty acid metabolism

The importance of n−6 and n−3 polyunsaturated fatty acids (PUFA) in neonatal development, particularly with respect to the developing brain and retina, is well known. This review combines recent information from basic science and clinical studies to highlight recent advances in knowledge on PUFA metabolism and areas where research is still needed on infant n−6 and n−3 fatty acid requirements. Animal, cell culture, and infant studies are consistent in demonstrating that synthesis of 22∶6n−3 involves C24 PUFA and that the amounts of 18∶2n−6 and 18∶3n−3 influence PUFA metabolism. Studies to show that addition of n−6 fatty acids beyond Δ6-desaturase alters n−6 fatty acid metabolism with no marked increase in tissue 20∶4n−6 illustrate the limitations of analyses of tissue fatty acid compositions as an approach to study the effects of diet on fatty acid metabolism. New information to show highly selective pathways for n−6 and n−3 fatty acid uptake in brain, and efficient path-ways for conservation of 22∶6n−3 in retina emphasizes the differences in PUFA metabolism among different tissues and the unique features which allow the brain and retina to accumulate and maintain high concentrations of n−3 fatty acids. Further elucidation of the Δ6-desaturases involved in 24∶5n−6 and 22∶6n−3 synthesis; the regulation of fatty acid movement between the endoplasmic reticulum and peroxisomes; partitioning to acylation, desaturation and oxidation; and the effects of dietary and hormonal factors on these pathways is needed for greater understanding of neonatal PUFA metabolism.     

Hydrocarbons from males,females, and larvae of pecan weevil:Curculio caryae (Horn)

As part of a program to identify as many as possible of the components of the pecan weevil,Curculio caryae (Horn), the hydrocarbons from males, females, and larvae were isolated by solvent extraction and column chromatography and subjected to gas liquid chromatographymass spectrometry analysis. n-Alkanes from C₁₄−C₃₂ in the larvae and unsaturated and branched chain hydrocarbons from C₂₀−C₃₂ in males and females were found. There are no significant differences between the hydrocarbons of the male and female pecan weevils.     

The effect of dietary erucic acid on cardiac triglycerides and free fatty acid levels in rats

Male Sprague-Dawley rats, 3 weeks of age, were fed semisynthetic diets containing test oils at 20% by weight for 3 days, 1 week, and 16 weeks. The test oils contained up to 22.3% erucic acid. Growth retardation was evident in rats fed rapeseed oil high in erucic acid, and soybean oil and Tower rapeseed oil diets containing about 5% erucic acid. Cardiac triglyceride accumulation was found in rats fed diets containing about 5% erucic acid but not in rats fed Tower rapeseed oil which contains 0.2% of this acid. The cardiac free fatty acid levels were low, 50–100 μg/g of wet heart tissue, and were not affected by feeding diets containing about 5% erucic acid. Feeding a diet containing a high erucic acid rapeseed oil did result in higher free fatty acid levels but only at 3 days and 1 week; the level at 16 weeks was similar to the other oils. The fatty acid analysis of cardiac triglycerides and free fatty acids showed high percentages of erucic acid at 3 days and 1 week; at 16 weeks these levels had declined significantly. The results indicate that the accumulated erucic and eicosenoic acids, at 3 days and 1 week, accounted for the increase in cardiac free fatty acids when rats were fed the high erucic acid rapeseed oil. There appears to be no evidence that the early cardiac triglyceride or free fatty acid accumulation is related to the formation of the long term myocardial lesions. Contribution No. 739 Animal Research Institute.