Pitch Production Research Articles

The Homeotropic Surface Anchoring Effects on the C-H Phase Transition

Two simple models are introduced to explane the homeotropic surface anchoring effects on the cholesteric to homeotropic (C-H) phase transition in the absence of an applied field. The calculations are extended to include the effect of an external field perpendicular to the surfaces. The results predict the C-H phase transition with analytical expressions involving the product of cell thickness and inverse pitch.

Upgrading of Pitch Produced by Mild Gasification of Subbituminous Cal

Alternative sources of anode binder pitch may be required in the future. One potential process for the production of pitch is low-temperature coal pyrolysis or mild gasification. Characterization data for a pitch produced by mild gasification of Powder River Basin subbituminous coal are reported. This pitch has acceptable sulfur, sodium, ash, and beta-resin levels but is shown to be deficient in aromatic carbon content and quinoline insolubles (QI). It also contains high levels of oxygen which leads to a high softening point and low coking value. Several strategies for upgrading this pitch to meet anode binder standards were investigated. These included heat treating, air blowing, solvent extraction, vacuum distillation, and addition of artificial QI

Methods for increasing yield and improving quality of petroleum pitches

In the work reported here, electrode pitches were obtained from a vacuum-reduced cracked resid (VCR) with an aromatic additive -- a heavy pyrolysis tar (HPT). A mixed charge with the required ratio of these components was heated at atmospheric pressure in a batch still unit. Timing of the run was started at the time initial decomposition (ffactionation) was observed, and the run was continued up to the formation of 50% distillate. The physicochemical characteristics of the components of the charge are listed in Table 1. The resuhs obtained in thermal processing of VCR, HPT, and blends of the two stocks are presented in Table 2. When the low-boiling aromatic additive is not present, the process is typical for cracked tars of this type. With increasing content of the HPT, the time corresponding to 50% distillate recovery becomes shorter. The longer time of 120 min that is observed for the blend with 5 % HPT can be explained by a "retardation effect" of thermocondensation processes that is observed in the thermal processing of cracked tars in mixture with a small amount of pyrolysis tar [4]. In the present series of experiments, the charge with 10% HPT proved to be optimal. From such a mixture, under otherwise equal conditions, a pitch with higher plasticity is obtained, with a greater yield. This pitch has a higher yield of coke residue and hence a higher pitch index (PI), which determines the processing and economic indexes of pitch production:

Producing a carbon fiber precursor by supercritical fluid extraction

Abstract Supercritical fluid extraction is being investigated for the production of mesophase pitch, a liquid crystalline precursor for the manufacture of high-performance carbon fibers. A continuous-flow apparatus is being used to fractionate an isotropic petroleum pitch feedstock with supercritical toluene at temperatures to 400 °C and pressures to 200 bar. This pitch was separated into isotropic and liquid crystalline, or mesophase, portions in a region of liquid-liquid equilibrium. Since the phases are opaque, an electrical impedance technique was used to monitor the location of the liquid-liquid interface. A 100% mesophase pitch was produced at 340 °C and 70 bar using a solvent-to-feed ratio of 3:1. This material was spun into 10 μm-diameter fibers which were oxidized, carbonized and tested for physical properties. The final fibers exhibit tensile strengths and moduli comparable to the best pitch-based fibers currently available. With these fiber properties and the continuous nature of this process, supercritical extraction is an attractive alternative to existing pitch treatment processes.

Song Sparrows Learn from Limited Exposure to Song Models

BORROR, D. J., AND W. W. H. GUiN. 1965. Variation in White-throated Sparrow songs. Auk 82:26-47. DossON, C. W., AND R. E. LEMON. 1975. Re-examination of the monotony-threshold hypothesis in bird song. Nature, Lond. 257:126-128. DossON, C. W., AND R. E. LEMON. 1977. Bird song as music. J. Acoust. Soc. Am. 61:888-890. DOOLING, R. J. 1982. Auditory perception in birds, p. 95-177. In D. E. Kroodsma and E. H. Miller [eds.], Acoustic communication in birds. Vol. 1. Academic Press, New York. FALLS, J. B. 1963. Properties of birdsong eliciting responses from territorial males. Proc. Int. Omrnithol. Congr. 13:259-271. HARTSHORNE, C. 1973. Born to sing. Indiana University, Bloomington, IN. HULSE, S. H., J. HUMPAL, AND J. CYNX. 1984. Discrimination and generalization of rhythmic and arrhythmic sound patterns by European Starlings (Sturnus vulgaris). Music Percep. 1:442-464. HURLY, T. A., R. G. WEISMAN, L. RATCLIFFE, AND I. JOHNSRUDE. 1991. Absolute and relative pitch production in the song of the White-throated Sparrow (Zonotrichia albicollis). Bioacoustics 3:81-91. LAMBRECHTS, M., AND A. DHONDT. 1987. Differences in singing performance between male Great Tits. Ardea 75: 43-52. NELSON, D. A. 1988. Feature weighting in speciessong recognition by the Field Sparrow, Spizella pusilla. Behaviour, 106: 158-182. WEARY, D. M. 1990. Categorization of song notes in Great Tits: which acoustic features are used and why? Anim. Behav. 39:450-457. WEARY, D. M., AND R. E. LEMON. 1988. Evidence against the continuity-versatility relationship in bird song. Anim. Behav. 36:1379-1383. WEARY, D. M., R. G. WEISMAN, R. E. LEMON, T. CHIN, AND J. MONGRAIN. 1991. Veeries use frequency ratio to sing and recognize songs. Auk 108:977981.

Songs of Two Mexican Populations of the Western Flycatcher Empidonax difficilis Complex

HURLY, T. A., L. RATCLIFFE, D. M. WEARY, AND R. WEISMAN. In press. White-throated Sparrows (Zonotrichia albicollis) can perceive pitch change using frequency ratio independent of frequency difference. J. Comp. Psych. MARLER, P. 1960. Bird songs and mate selection, p. 348-367. In W. E. Lanyon and W. N. Tavolga [eds.], Animal sounds and communication. American Institute of Biological Sciences, Washington, DC. NELSON, D. A. 1989. The importance of invariant and distinctive features in species recognition of bird song. Condor 91:120-130. RICE, W. R. 1989. Analyzing tables of statistical tests. Evolution 43:223-225. RICHARDS, D. G. 1981. Estimation of distance of singing conspecifics by the Carolina Wren. Auk 98:127-133. SHACKLETON, S. A. 1991. Singing behaviour of Black-capped Chickadees (Parus atricapillus). M.S .thesis, Queen's University, Kingston, Ontario, Canada. WEARY, D. M., R. G. WEISMAN, R. E. LEMON, T. CHIN, AND J. MONGRAIN. 1991. Use of the relative frequency of notes by Veeries in song recognition and production. Auk 108:977-981. WEISMAN, R., AND L. RATCIFFE. 1989. Absolute and relative pitch processing in Black-capped Chickadees, Parus atricapillus. Anim. Behav. 38:685692. WEISMAN, R., L. RATCLIFFE, I. JOHNSRUDE, AND T. A. HURLY. 1990. Absolute and relative pitch production in the song of the Black-capped Chickadee. Condor 92:118-124.

The Effect of Homeotropic Surface Anchoring on the Critical Voltage for Unwinding the Cholesteric Phase

Abstract Experimental data are presented for the unwinding of the helical cholesteric structure in the presence of an applied electric field. Homeotropic surface anchoring conditions are known to reduce the magnitude of the critical unwinding voltage which depends on helical pitch and cell thickness. The experiments are unique in that the pitch is varied continuously at constant cell thickness rather than changing thickness at constant pitch. This is accomplished by employing cholesteric mixtures in which the inverse pitch changes linearly with temperature in the nematic compensation region. A model introduced by Cladis and Klemen, and extended by Goossens, is used to explain the effect of surface anchoring in the absence of an applied field. The calculations are extended to include the effect of the field, and the theory predicts a universal critical voltage curve involving the product of cell thickness and inverse pitch which is verified by experiment.

Production of petroleum electrode pitches by compounding

Production of petroleum electrode pitches by compounding

Production of thermal pitch in severe processing of crudes

Production of thermal pitch in severe processing of crudes

Absolute and Relative Pitch Production in the Song of the Black-Capped Chickadee

Black-capped Chickadee (Parus atricapillus) song consists of two notes, termed fee and bee. Frequency measures at three key points (at the start and end of fee, and at the start of bee) were obtained from the songs of a large sample of chickadees (n = 151) in the wild. In this sample, 19 birds produced songs shifted downward in frequency as well as their normal songs. Analysis of normal song revealed that fee declines in frequency in a glissando of nearly pure tone, then continues at greatly reduced amplitude at the start of bee; whereas bee, also a nearly pure tone, is always lower in frequency than either the start or end offee. The absolute pitches (frequencies) of these measures vary substantially among birds, but much less within individuals. In contrast, pitch intervals (ratios of higher to lower frequencies) for frequency changes among the three measures are highly invariant among birds. Moreover, chickadees with normal and frequency-shifted songs maintain virtually the same pitch intervals in both. This analysis suggests that the absolute and relative pitch constancies in chickadee song production may provide information for individual and species recognition, respectively.

Real-time Visual Feedback in the Development of Vocal Pitch Accuracy in Singing

It has been conjectured that the development of vocal pitch accuracs Mn siiging is partly determined by the quality of feedback available to an error labelling schema (Welch. 1985 [a] and lb]). As a practical applicationl of this theoretical construct to the classroom, a micro-computer-based nvsteni (Howard and Welch, 1987) has been developed to provide real-time visual feedback of vocal pitch production to the user. This system has recentiv undergone initial trials with a class of seven-year-old children in a Bristol school. The sample (n =32) was divided into three matched groups: (a) experimental interactive, (b) experimental non-interactive, and (c) control, based on an initial system-driven assessment of their socal pitch accuracy Groups (a) and (b) used the system and the control group (c) uindertook singing activities of a more traditional nature. After one schoiol term. socal pitch accuracy was re-assessed. The two experimental groups recorded a signiticant improvement in their vocal pitch matching ability cmpared to the control group. The results are seen as supportive of the previouLslv stated theoretical position and confirm that action can encouralrac the underlsin.it developmental process (Welch, 1986).

Production of petroleum pitches by thermal condensation and plasticization

Production of petroleum pitches by thermal condensation and plasticization

Production of petroleum pitch by combined processing scheme

This article examines one version of a combined process in a single process unit for thermocondensation of heavy pyrolysis tar, obtaining several grades of petroleum electrode pitch and a pitch distillate. The unit contains two sections: a reactor section with series connected reactors, and a mixing section. In the reactors, the heavy pyrolysis tar undergoes a thermocondensation process, yielding 37-40% still bottoms (pitch). The scheme for obtaining various petroleum pitches in a combined process was tested under laboratory conditions. The process conditions are shown along with characteristics of the pitch obtained by thermocondensation and compounding.

Production of pitches in exhaustive crude oil processing schemes

A flow plan was created for the combination of a petroleum pitch production section with a commercial unit for delayed coking of petroleum resids. The pitch production section included a heater furnace, pitch-forming reactor, tower for fractionation of the light products of thermal condensation, and a heated receiver tank. Petroleum pitch was produced at temperatures lower than those typical in petroleum coke production a section for production of petroleum cracking pitch for various applications can be incorporated into thermal cracking units.

Structural characterization of pitch feedstocks for coke making: Use of 13C coupled 1H n.m.r. spectroscopy

Several pitches, used to make high-grade cokes, are characterized by 13C and 1H n.m.r. spectroscopy. Average molecular parameters of solvent fractions of the pitches indicate distinct differences in molecular structure. Principal differences between A-240 petroleum and medium coal-tar pitches are composition of fractions, aromaticity, degree of aromatic condensation and amount of naphthenic groups. The mild conditions of production of A-240 petroleum pitch leads to the formation of methylene bridges and biaryl linkages between two aromatic moieties in constituent molecules.

Production of petroleum pitches from heavy cracked tars

The influence of the vacuum distillate recycle ratio on the yield of pitch from the Groznyi cracked tar, on the quantity of coke deposits, and on the time of polycondensation of volatile matter in the pitch to 65% by weight is shown. The following properties of the cracked tar are given: density; carbon residue; ash by weight; sulfur content by weight; and hydrocarbon group composition by weight which includes paraffins, naphthenes, moni-, bi-, and polycyclic aromatics, resins, asphaltenes, and carboids. The authors propose a process flow plan for a high-rate process of pitch manufacture from cracked tars on the basis of the results obtained in these studies. The process can be recommended for evaluation on an experimental-commercial scale.

Tonality perception and comprehension: Pitch‐interval interactions

Two experiments investigated the influence of pitch and melodic interval on tonal comprehension and melodic expectation. The stimulus examples for both experiments were composed of a tonal context example followed by a two‐tone melodic fragment. The two‐way factorial design had 12 levels of ending pitch and 25 levels of melodic interval (all intervals within one octave of ending pitch). Subjects in experiment 1 rated how well the melodic fragment fit into the context example tonality. Ratings were three‐dimensional: (1) pitch‐interval interactions corresponding to a diatonic hierarchy, (2) perception of the dominant and tonic, and (3) perception of the three major diatonic triads. Subjects in experiment 2 sang their expected continuations to the melodic fragment. The continuations were influenced by factors similar to those of experiment 1. Continuation profiles could be reconstructed by multiplying corresponding entries from pitch and interval marginal mean profiles, implying that pitch and interval continuation production systems are functionally independent and produce a single response profile by means of a cross‐correlational decision mechanism. Ratings and continuations can be explained by a harmonic mapping model, where the harmonics of a response tone map onto those of the tonic and the first tone of the fragment.

A Schema Theory of How Children Learn to Sing in Tune

The literature on children's singing reveals that, for each age group, there are some children who cannot sing in tune. These children are labelled "poor pitch singers" (p.p.s.). The literature suggests that singing in tune is not simply a question of "can" or "cannot" but rather a continuum of skill with several degrees of competence. In general, the numbers of p.p.s. within sample populations declines with age, with boys outnumbering girls by 2 or 3 to 1. The customary method of treating this disability, although implying that improvement is possible, has only shown limited success. Reference to the psychological literature on feedback, however, suggests that, (1) learning can only take place when Knowledge of Results (KR) is present, and (2) variety of experience rather than repeated measures of the same kind may be more conducive to producing "novel" patterns of behaviour. Applying these findings to the mechanism of singing, a schema theory of how children learn to sing in tune is proposed, under which a recall and recognition schema are hypothesised as being responsible for vocal pitch production, and vocal pitch accuracy is determined by the efficiency of an error labelling schema.

A Population-Based Case-Control Study of Renal Cell Carcinoma

A population-based case-control study of renal cell carcinoma (495 cases and 697 controls) in the Minneapolis-St. Paul seven-county metropolitan area implicated cigarette smoking as a risk factor with an odds ratio (OR) among men of 1.6 (95% confidence intervals: 1.1-2.4) and among women of 1.9 (1.3-3.0). A statistically significant dose response was observed in both sexes for pack-years of cigarette use. On the basis of calculations of attributable risk, it was estimated that 30% of renal cell cancers among men and 24% among women were due to smoking. High relative adult weight as measured by the body mass index (BMI) was found to be a major risk factor among women but not among men, with those in the highest 5% of the BMI having an OR of 5.9 (1.8-20.4) in comparison to the lowest quartile. This association with excess weight was not seen at age 20, but it became more pronounced with increasing age, suggesting that the primary influence of weight gain is during the late stages of renal carcinogenesis. Excess risks were also related to ethnic background (particularly, German), which may account in part for the elevated incidence of renal cancer in the North Central area of the United States. In addition, positive associations were observed for long-term use of phenacetin-containing analgesics, heavy meat consumption, and heavy tea drinking (females only). An occupational clue was provided by an increased risk for exposure to petroleum, tar, and pitch products. Excesses of certain urologic and cardiovascular diseases were also observed among the cases compared to controls.

4427531 Process for deasphaltenating cat cracker bottoms and for production of anisotropic pitch

A process for removing asphaltenes present in cat cracker bottoms is disclosed. Basically, the process requires removal of at least a portion of the polynuclear aromatic oils present in the cat cracker bottom, for example, by vacuum stripping, whereby the asphaltenes are thereafter capable of being extracted from the so-treated cat cracker bottom. Heat soaking of the asphaltene-free cat cracker bottom results in a pitch particularly suitable for carbon artifact manufacture.