Size Exclusion Chromatography-Inductively Coupled Plasma Atomic Emission Spectrographic Study of Fe In Bitumens Derived from Tar Sands

Abstract

Bitumens extracted from tar sands from various locations (Utah. California. Kentucky, and Alberta) were examined by size exclusion chromatography with on-line element-specific detection to study the Fe concentration as a function of size. In most cases, the resulting profiles exhibit unimodal distributions at relatively large molecular size with very similar times for maximum elution. Specifically, Sunnyside (Utah) and McKittrick (California) tar-sand bitumens exhibited very intense maxima consistent with extremely high bulk Fe contents. Arroyo Grande (California) exhibited an additional maximum at very large molecular size. This size behavior of the Fe appears to correlate with the large molecular size Ni and V components eluted under the same conditions.     

Net absorption of macrominerals by portal-drained viscera of lactating Holstein Cows and beef steers

Net absorption of macrominerals by portal-drained viscera of cattle was measured in two experiments. In Experiment 1, net portal-drained visceral and liver flux of Na, K, Ca, P, and Mg were measured in four lactating Holstein cows fed a 60:40 corn silage:concentrate diet ad libitum and milked at 12-h intervals. Twelve measurements of net flux (venous-arterial concentration difference x blood plasma flow) were obtained hourly at 4 and 8 wk postpartum. Intake of DM and milk yield averaged 15.6 and 32.2 kg/d, respectively. Excluding Na, net absorption of these macrominerals was measurable across portal-drained viscera. Flux of Na was negative at wk 4 postpartum (net removal from blood) and positive at wk 8 (net absorption into blood). Excluding Mg, differences in venous-arterial concentrations for macrominerals across the liver were not different from zero. In Experiment 2, net portal-drained visceral flux of Na, K, Ca, P, and Mg was partitioned into stomach and poststomach sections in two Hereford steers. Poststomach tissues accounted for essentially all such absorption of K, Ca, and P and, on a net basis, removed Na and Mg. Stomach tissues absorbed Mg and small amounts of K, Ca, and P. Net stomach flux of Na was positive, denoting net absorption, but highly variable. Net portal-drained visceral absorption of K increased with intake in both experiments. Net portal-drained visceral absorption of P was greater than total intake in both experiments, reflecting recycling of P via saliva and other digestive secretions.     

Net energy for lactation of calcium salts of long-chain fatty acids for cows fed silage-based diets.

The NEL of calcium salts of long-chain fatty acids from palm oil was determined in mature Holstein cows. Twelve lactating (fed for ad libitum intake) and six nonlactating (restricted to near maintenance intake) Holstein cows were fed 0 or 2.95% fat supplement in diets formulated to contain 16 or 20% CP in a 2 x 2 factorial arrangement of treatments in a single reversal design within protein level. The fat supplement was substituted for ground corn and minerals. Two 6-d total collection balance trials were conducted during which cows were in open circuit respiration chambers. Intake of OM was lower for lactating cows fed the fat supplement (18.1 vs. 19.1 kg/d), but energy intake did not differ (93.2 Mcal/d). Total long-chain fatty acid intake was increased from 477 to 820 g/d with fat feeding. Apparent digestibility of long-chain fatty acids was increased 11.1 percentage units with increased dietary CP for lactating cows with no difference in fatty acid digestibility for the dry cows. Milk yield was higher (34.3 vs. 32.0 kg/d) with fat feeding, but milk energy yield did not differ (22.6 Mcal/d). The NEL of the fat supplement was estimated from the incremental differences in energy values within cows, assuming NEL of corn replaced by fat to be 1.96 Mcal/kg DM, and was determined to be 6.52 Mcal/kg DM (SE = 1.74). The efficiency of the use of metabolizable energy for lactation from dietary fat was 77.2%. The energy in calcium salts of long-chain fatty acids is utilized efficiently for lactation in mature cows.     

TRANSIENT THERMOELASTIC FRACTURE OF INTERFACE CRACKS

Abstract

The transient behavior of an interface crack at the center and edge of two finite dissimilar materials free to bend and subjected to a transient thermal load was studied. It was first assumed that the crack was insulated. The effect of allowing heat to conduct through the crack upon closing was also investigated. The effects of the mechanical and thermal material property ratios as well as the thickness ratio on the crack deformations and the transient strain energy release rate were calculated.     

Near‐Infrared Light‐Emitting Diodes (LEDs) Based on Poly(phenylene)/Yb‐tris(β‐Diketonate) Complexes

Near‐infrared‐emitting electroluminescent (EL) devices using blue‐light‐emitting polymers blended with the Yb complexes Yb(DBM)₃phen (DBM = dibenzoylmethane), Yb(DNM)₃phen (DNM = dinaphthoylmethane), and Yb(TPP)L(OEt) (L(OEt) = [(C₅H₅)Co{P(O)Et₂}₃]^–) have been studied. EL devices composed of Yb(DNM)₃phen blended with PPP‐OR11 showed enhanced near‐IR output at 977 nm when compared to those fabricated with Yb(DBM)₃phen/PPP‐OR11 blends. The maximum near‐IR external efficiencies of the devices with Yb(DBM)₃phen and Yb(DNM)₃phen are, respectively, 7 × 10^–5 (at 6 V and at 0.81 mA mm^–2) and 4 × 10^–4 (at 7 V, and 0.74 mA mm^–2). The optimal blend composition for EL device performance consisted of PPP‐OR11 blended with 10–20 mol‐% Yb(DNM)₃phen. A device fabricated using Yb‐(TPP)L(OEt)/PPP‐OR11 showed significantly enhanced near‐IR output efficiency, and future efforts will focus on devices fabricated using porphyrin‐based materials.     

EFFECT OF PREHYDROGENATION ON HYDROCONVERSION OF MAYA RESIDUUM, PART II: HYDROGEN INCORPORATION

Maya 650° F residuum (Maya AR) was prehydrogenated over a standard hydroprocessing catalyst. The 650°F residuum of this product lpar;HMaya ARrpar; and Maya AR were then separately hydroprocessed further at selected conditions. The products were examined by elemental, ¹H, and ¹³C NMR analyses to determine the how hydrogen was incorporated during processing.

For all processing steps, hydrogen was incorporated in capping fragments formed during cracking reactions, as well as in hydrogenation reactions, heteroatom removal, and hydrocarbon gas formation, but the distribution of the hydrogen was dependent upon the type and severity of the process: For the direct hydroconversion of Maya AR, 25 to 30% of the total hydrogen was incorporated for heteroatom removal and hydrocarbon gas formation. The remaining hydrogen was incorporated in hydrogenation and cracking reactions.

For the two-step hydroconversion process, 30 to 40% of the total hydrogen was incorporated for heteroatom removal and hydrocarbon gas formation. The remaining was primarily incorporated in hydrogenation reactions. Some was incorporated into cracking reactions in the moderate severity case, but almost none was seen in the low severity case.

The hydrogen incorporation during each specific processing step is discussed, along with an evaluation of the prehydrogenation step a residuum conversion process option. These results will be also compared to previously reported hydrogen incorporation measurements on other feeds and processing methods.     

Determination of mechanical properties of Al–Mg alloys dissimilar friction stir welded interface by indentation methods

A series of friction stir welds was produced between heat treated Al–Mg–Si and strain hardened Mg–Al–Zn alloy sheets. Weld evaluation by transverse tensile testing showed a wide range of strengths and all the failures occurred along the weld interface. The formation of intermetallic compounds in the weld joints was investigated by X-ray diffraction, scanning electron microscopy imaging, and elemental analysis techniques. Micro and nanoindentation characterization methods were used to evaluate the mechanical properties at the interface, including the fracture toughness. The fracture toughness measurements by a Vickers indenter introduced Palmqvist type cracks at all four corners of the indents and cube corner indenter resulted in the intermetallic chipping. The fracture toughness (K _IC) calculation by both the micro and nanoindentation methods showed very low values, which is the primary reason for the brittle failure of the dissimilar weld joints and concomitant low tensile strengths.     

Effect of communication media on developmental relationships: Self-reported and observed behaviors

This study examined the effect of four communication modes (computer-based video teleconferencing, computer-based electronic chat, telephone, and face-to-face) on developmental interactions between dyads; specifically on the transmission of psychosocial versus instrumental information. The dyads consisted of undergraduates at a southeastern university. One member of the dyad was an incoming first year student; the second member was an upper division student who served as a developmental coach. The study was experimental in design, which controlled the amount of interaction, the frequency of interaction, and prior acquaintanceship of the dyadic pair. The small amount of variance attributable to communication mode suggests that people matter more than the machines. Specifically, in terms of implementing non-face-to-face developmental programs, it might be more useful to focus on reducing the variability in the coaches’ behaviors through selection or training, than to focus on communication mode. Additionally, independent observers watched and rated the dyadic interactions to provide a third point of view. There was very little overlap between coach and trainee perceptions, although there was considerable agreement between the raters’ and coaches’ ratings.     

Timely Timelessness: Traditional Proportions and Modern Practice in Kahn’s Kimbell Museum

The twentieth century witnessed declining interest in architectural proportioning systems, which were virtually eclipsed by technical, social and fiscal agendas. Louis Kahn is a seminal architect, whose most acclaimed building, the Kimbell Art Museum (1966–72), represents a compelling case-study in the use proportions by twentieth-century architects. In spite of a raft of peculiarly modern restrictions (both technological and programmatic), Kahn appears – despite his espoused ambivalence concerning proportion – to have intentionally produced a building with an array of approximate geometrical as well as precise harmonic proportions. This two-part paper presents the findings of a multifaceted research project that examined the Kimbell’s proportions from numerous standpoints. Part 1 presents a textural analysis of Kahn’s statements regarding proportion, as well as the findings of an archival study of correspondence between the architect and his client and consultants. Part 2 presents a prima facie geometrical analysis of the construction drawings for the project. The division into parts reflects an apparent discrepancy between Kahn’s buildings and what he had to say about them.     

Neighborhood effects in reading aloud: New findings and new challenges for computational models.

A word from a dense neighborhood is often read aloud faster than a word from a sparse neighborhood. This advantage is usually attributed to orthography, but orthographic and phonological neighbors are typically confounded. Two experiments investigated the effect of neighborhood density on reading aloud when phonological density was varied while orthographic density was held constant, and vice versa. A phonological neighborhood effect was observed, but not an orthographic one. These results are inconsistent with the predominant role ascribed to orthographic neighbors in accounts of visual word recognition and reading aloud. Consistent with this interpretation, 6 different computational models of reading aloud failed to simulate this pattern of results. The results of the present experiments thus provide a new understanding of some of the processes underlying reading aloud, and new challenges for computational models. (PsycINFO Database Record (c) 2011 APA, all rights reserved)