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The quenched solid density functional theory (QSDFT) is employed to study methane adsorption on coal at geological conditions. The main focus is made on coal deformation in the course of adsorption that may result in either expansion/swelling or contraction, depending upon the pressure, temperature, and pore size. Two qualitatively different types of deformation behavior were found depending upon the pore width. Type I shows a monotonic expansion in the whole pressure range. This behavior is characteristic for the smallest pores <1.3σff (0.5 nm) that cannot accommodate more than one layer of methane. Type II displays contraction at low pressures followed by expansion. Type II behavior was found for several groups of pores, which can accommodate dense packing with an integer number (from 2 to 6) of adsorbed layers. The results of the QSDFT model are compared to literature experimental data, and the model is employed to study the adsorption behavior of model coals at elevated pressures and temperatures. We established the relationships between the methane capacity and the solvation pressure that it exerts on the coal matrix and the depth of coal bed for pores of different sizes. We found that the coal deformation depends upon the bed depth, and at different depths, it either swells or contracts depending upon the pore size distribution. The implications of these findings for evaluating coal gas resources and coal mine recovery are discussed.

High-density polyethylene (HDPE) was pyrolyzed over HZSM-5 catalyst using a specially developed laboratory fluidized-bed reactor operating isothermally at ambient pressure. The influence of reaction conditions including temperature, ratios of HDPE to catalyst feed, and flow rates of fluidizing gas was examined. The sodium form of siliceous ZSM-5, silicalite, containing very few or no catalytically active sites, gave very low conversions of polymer to volatile hydrocarbons compared with HZSM-5 (Si/Al ) 17.5) under the same reaction conditions. Experiments carried out with HZSM-5 gave good yields of volatile hydrocarbons with differing selectivities in the final products dependent on reaction conditions. Catalytic pyrolysis of HDPE performed in the fluidized-bed reactor was shown to produce valuable hydrocarbons in the range of C 3 -C 5 carbon number with a high olefinic content. The production of olefins with potential value as a chemical feedstock is potentially attractive and may offer greater profitability than production of saturated hydrocarbons and aromatics.

The purpose of this research was to further investigate the information processing model suggested by Benjamin, McKeachie, Lin, and Holinger (1981) in explaining the poor academic performance of highly test-anxious students. Whereas previous studies pointing to deficits in the organization stage of processing mainly relied on self-reports, the first study of this research used a technique that enabled us to measure objectively the organization of course material by students in a nonevaluative situation. Results indicated that highly test-anxious students showed a disadvantage in organization of course material, in comparison with other students. In the second study, we investigated whether types of highly test-anxious students can be differentiated by their information processing skills. The first type includes those with good study habits who do not have problems in encoding and organizing the information but, rather, have a major problem in retrieval for a test. The second type includes those with poor study habits who have problems in all stages of processing. Such a distinction was supported by results comparing performance of these types of highly test-anxious students in an evaluative and a nonevaluative situation.Studies conducted in the last 30 years have generally supported the notion that high test anxiety is correlated with performance decrements (Benjamin, McKeachie, Lin, & Holinger, 1981;McKeachie, 1984;McKeachie, Pollie, & Spiesman, 1955). Numerous researchers have investigated the causes of these decrements in performance. According to traditional test-anxiety theory, a high anxiety level produces task-irrelevant responses, for example, error tendencies and worry that interfere with task-relevant responses necessary for good performance (Wine, 1971). As a result, much of the work on treatment strategies has been focused on the feelings and physiological reactions involved. Treatments aimed at relaxation or reducing emotional reactions to test situations, however, have had little effect on performance (Tryon, 1980). Desiderato and Koskinen (1969), Wittmaier (1972), and Culler and Holahan (1980) concluded that the poor academic performance of highly test-anxious students was due, at least in part, to inadequate study skills, resulting in poor knowledge of the relevant material. Benjamin et al. (1981), Tobias (1977), and Mueller (1980 suggested the use of an information processing model, which combines the aforementioned interference and study-habits models for the analysis of test anxiety. Such a model explains the performance deficit of highly test-anxious students in terms of problems in encoding and organizing information as well as in retrieval of this information in a test situation. To support their position, Benjamin et al. (1981) compared students with high, medium, and low test anxiety in an upper level psychology course.

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This article presents a new method of inferring students' cognitive structures and their development in a college course. The method, a modification of Reitman and Rueter's (1980) "ordered tree technique," generates a unique structure that displays important relationships assumed to be in a student's memory about concepts taken from a specific field of study. The usefulness of this method was assessed in two studies that used subject matter from a full-scale university course. Results showed the technique to be meaningful, since it differentiated between students with different levels of achievement. In addition, the four measures produced by the method -grouping, hierarchical structure, directionality of the structure, and similarity to the instructor -showed development throughout the courses and were related to academic performance. The characteristics of the method are discussed in light of other ways of inferring cognitive structure.We thank Ilan Elior and Miles Light for their help in analyzing these data and Judith Reitman Olson and Henry Rueter for their comments on a draft of this article.