Introduction of Process Life Cycle Inventory in Environmental Engineering Education

Environmental issues are usually included in process design and operation. Once mass and energy balances have been completed, the life cycle inventory (LCI) can be carried out with an environmental load balance. This paper discusses a methodology for developing this balance, which can be taught at the same level of chemical engineering fundamentals at which basic mass and energy balances are dealt with. The LCIs of electricity and steam produced by a co-generation unit and conventional plants are compared to illustrate the method.     

DIAGNOSING STUDENTS' ERRORS FROM THEIR RESPONSE SELECTIONS IN LANGUAGE ARTS

This set of studies examined the consistency of student response patterns on a test of language arts, as a first step toward designing a computerized adaptive test to diagnose errors. A diagnostic domain-referenced language arts test was designed so that the choice of response would immediately point to a specific misconception in pronoun usage. This direct correspondence between error and diagnosis was designed to facilitate classroom instruction and remediation. Analysis of students' response choices on matched items and analysis of students' rationales for selecting their responses showed that student behavior was not always consistent and could be used to diagnose some errors but not others.     

一束番红花

It brought all the assurance I needed. 它带来了我所需要的那种自信。那是一个秋日清晨,我与丈夫迁入新居不久。孩子们在楼上整理物品,透过窗户,我发现父亲正在前面的草坪上神秘地来回走动着。我父母就住在附近,父亲已经看望我们多次了。我问他: “你在那儿忙什么?”他抬起头,笑了笑。说:“我要给你一个惊     

Indirect evidence of human skeletal muscle damage and collagen breakdown after eccentric muscle actions

Indirect markers of muscle damage and collagen breakdown were recorded for up to 9 days after a bout of concentric, followed by a bout of eccentric, muscle actions. Nine untrained participants performed two bouts of 50 maximum effort repetitions on an isokinetic dynamometer (angular velocity 1.05 rad.s-1, range of motion 1.75 rad). An initial concentric bout of muscle actions was followed by an eccentric bout 21 days later, using the same knee extensors. Concentric actions induced no changes in maximum voluntary isometric contraction force (MVC),nor induced any changes in the serum enzyme activities of creatine kinase, a lactate dehydrogenase isoenzyme (LDH-1), or alkaline phosphatase. Similarly, concentric actions induced no change in markers of collagen breakdown,namely plasma hydroxyproline and serum type 1 collagen concentration.In contrast,eccentric actions induced a 23.5 ± 19.0% (mean ± s) decrease in MVC immediately post-exercise (P< 0.05), and increased the serum enzyme activities of creatine kinase and LDH-1 to 486 ± 792 and 90 ± 11 IU.l-1 respectively on day 3 post-exercise, and to 189 ± 159 and 96 ±13 IU.l-1 respectively on day 7 post-exercise (all P < 0.05). Eccentric actions induced no significant changes in plasma hydroxyproline, but increased collagen concentration on days 1 and 9 post-exercise (48.6% and 44.3% increases above pre-exercise on days 1 and 9 respectively; both P < 0.05). We conclude that eccentric but not concentric actions may result in temporary muscle damage, and that collagen breakdown may also be affected by eccentric actions. With caution, indices of collagen breakdown may be used to identify exercise-induced damage to connective tissue.