Effects of dietary oils and methyl ethyl ketone peroxide onin vivo lipid peroxidation and antioxidants in rat heart and liver

Weanling male Sprague-Dawley rats were fed diets for four weeks which differed in their content of n−6 (corn oil; CO) and n−3 fatty acids (fish oil; FO), but were similar in their content of saturated and monounsaturated fatty acids and vitamin E. At the end of the four-week feeding period, each dietary group was subdivided into two groups. One group received a single placebo injection of α-tocopherol-stripped corn oil (TSCO); the other group received a single injection of the free radical generator, methyl ethyl ketone peroxide (MEKP), in TSCO. Twenty-four hours after injection, the effect of dietary oil and MEKP treatment on endogenous lipid peroxide (LPO) production (measured as methylene blue formed by the “Determiner LPO” assay), glutathione (GSH) and vitamin E content, and fatty acid composition of phosphatidylcholine and phosphatidylethanolamine in heart and liver from unfasted animals were measured. FO-fed rats had significantly heavier hearts and livers, increased levels of n−3 fatty acids in membrane phospholipids, and higher liver LPO levels than CO-fed rats. MEKP treatment resulted in significantly lower body weights and liver GSH levels. The data indicate that dietary n−3 fatty acids increase lipid peroxidation in liver somewhat more than in heart. The study also demonstrates that the effect of induced oxidative stress due to a single dose of MEKP on lipid peroxide formation and antioxidant status in tissues from unfasted animals was independent of the dietary oils.     

Particle and Granule Parameters Affecting Compaction Efficiency in Dry Pressing

The slope of density versus log (pressure) represents the efficiency of compaction forming. A high maximum particle packing density of powders increased the pressing efficiency and the compact density. A high granule density favors a high compact density, whereas, a low granule density favors an increase in the pressing efficiency and the elimination of the intergranular pores; an optimum clearly existed. At a very low forming pressure, the compact density using granules containing a binder was lower; but at a higher forming pressure, the binder acted as a lubricant and assisted particle sliding and rearrangement which increased the pressing efficiency and compact density.     

Experimental investigations of long stick wood gasification in a bottom lit updraft fixed bed gasifier

Based on the experience of the gasifier users on the efforts and energy for wood chip preparation in a typical gasifier, we have embarked on the development of a gasifier suitable to work with long stick woody biomass as the feed materials. In the context of the impact of gasifiers, as decentralized energy delivery devices such an approach, it is hoped, would be an attractive option in rural areas both in domestic and industrial sectors. In the present paper in the gasifier operation, there is a fixed quantity of char that is combusted to gasify a fixed amount of wood, and the gasifier does not operate in a steady state manner. In this present work, focus is made on the development of a gasifier using long sticks of wood as feed materials. With this concept, a 10 kW thermal output power gasifier is designed and constructed. The gas and airflows can be converted to the air/fuel ratio, the most important aspect of gasifier operation. The air/fuel ratio shows operation in a combustion mode at start up, a gasification mode for the middle part of the run and a charcoal gasification mode at the end of the run. Since the interest here is exploring and validating of this concept, a bottom lit updraft gasifier is designed mainly to look at the gas yield and other favourable factors and to use this gas so obtained for thermal applications. The rate of feed was between 9 and 10 kg/h and continuous operation for 5 h was made in a couple of runs to study the performance. In this paper we report the salient features of our efforts and results, yielding a gasifier efficiency of 73%.     

Biodegradable polymers for use in surgery — poly(glycolic)/poly(Iactic acid) homo and copolymers: 2. In vitro degradation

The degradation mechanism of a series of polyglycolic/polylactic acid, (PGA/PLA), homo and copolymers synthesized as in Part 1¹, has been studied _vitro. An in vitro test model similar to that described in a previous study⁹, was used. The effects of time, temperature and pH on the rate and mechanism of degradation were elucidated. The degree of degradation was monitored molecularly by gel permeation chromatography (g.p.c.), tensile strength determination and mass loss measurements. The mechanism of degradation is shown to be by hydrolysis. The copolymers of PGA and PLA are shown to have a wide range of degradation rates governed by the hydrophilic/hydrophobic balance and crystallinity of the respective copolymer. The effect of the glass transition temperature (T_g) of PGA on its sensitivity to degradation is also demonstrated.     

Application Development Productivity Tools: A Survey Of Importance and Popularity

Application development productivity is becoming an increasingly important issue in the MIS department. Unfortunately, dramatic improvements in hardware performance have not been matched with corresponding advances in software development, even though there have been significant investments in productivity tools. This article identifies a range of productivity tools and presents results from a survey of MIS managers that reveals which specific tools are being used and their relative importance to software development productivity.     

Cell-free apoptosis in Xenopus egg extracts: inhibition by Bcl-2 and requirement for an organelle fraction enriched in mitochondria

Apoptotic cell death involves a ritual series of morphological changes, presumably reflecting a conserved molecular pathway. We now report that the nuclear events typical of apoptosis can be reproduced in "apoptotic" Xenopus egg extracts. In this cell-free system, nuclear assembly and protein import are initially normal; after 2-4 hr, however, a process of nuclear destruction ensues involving chromatin condensation and the shrinkage and fragmentation of the nuclei. This apoptotic process, which also occurs in nuclei added exogenously, is blocked by the addition of baculovirus-expressed Bcl-2 protein. To block the disintegration of nuclei that are added later, Bcl-2 must be present during this latent period. "Apoptosis" in these extracts requires a dense organelle fraction enriched in mitochondria. The cell-free system described here provides a novel tool for understanding intracellular events in apoptosis and the inhibitory function of Bcl-2.     

SATCHMORE: SATCHMO with RElevancy

We introduce a relevancy detection algorithm to be used in conjunction with the SATCHMO prover. The version of SATCHMO considered here is essentially a bidirectional prover, utilizing Prolog (back chaining) on Horn clauses and forward chaining on non-Horn clauses. Our extension, SATCHMORE (SATCHMO with RElevancy), addresses the major weakness of SATCHMO: the uncontrolled use of forward chaining. By marking potentially relevant clause head literals, and then requiring that all the head literals be marked relevant (be totally relevant) before a clause is used for forward chaining, SATCHMORE is able to guide the use of these rules. Furthermore, the relevancy testing is performed without extending the proof search beyond what is done in SATCHMO. A simple implementation of the extended SATCHMO can be written in Prolog. We describe our relevancy testing approach, present the implementation, prove soundness and completeness, and provide examples that demonstrate the power of relevancy testing.This research was partially supported by NSF Grants IRI-8805696 and CCR-9116203. This paper is a major revision of Wilson and Loveland (1989).     

Low cycle fatigue life prediction in shot‐peened components of different geometries—part I: residual stress relaxation

In this study, the residual stress relaxation behaviour occurring during low‐cycle fatigue in shot‐peened specimens with either a flat or a notched geometry has been studied. A representative low‐pressure steam turbine material, FV448, was used. The residual stress and strain hardening profiles caused by shot peening were measured experimentally and were then incorporated into a finite element model. By allowing for both effects of shot peening, the residual stress relaxation behaviour was successfully simulated using this model and correlated well with the experimental data. Although more modelling work may be required to simulate the interaction between shot peening effects and external loads in a range of notched geometries, the model predictions are consistent with the specimens tested in the current study. The novelty of this study lies in the development of such a modelling approach which can be used to effectively simulate the complex interaction between shot peening effects and external loads in notched regions. Compared with the un‐notched geometry, the notched geometry was found to be more effective in retaining the improvement in fatigue life resulting from shot peening, by restricting the compressive residual stress relaxation during fatigue loading.     

Effects of attitudes and behaviours on learning mathematics with computer tools

This mixed-methods study investigates the effects of student attitudes and behaviours on the outcomes of learning mathematics with computer tools. A computer tool was used to help students develop the mathematical concept of function. In the whole sample (N = 521), student attitudes could account for a 3.4 point difference in test scores between individuals on a 10-point scale. General attitude towards mathematics positively predicted test scores. However, more able students who were well-disposed towards mathematical computer tools achieved lower scores. Self-reported behaviours were unrelated to test scores. Detailed observation of a small number of students (N = 8) revealed that positive attitudes towards mathematics and mathematical computer tools augmented exhibited learning behaviours, and that both a positive attitude to mathematical computer tools and exhibited learning behaviours benefited tool mastery. Although tool mastery and test scores are intimately related, reflective processes appear to mediate this relationship. Promoting learning with mathematical computer tools needs to take several factors into account, including improving student attitudes, raising levels of learning behaviours, and giving sufficient opportunity for constructing new mathematical knowledge within meaningful mathematical discourse.     

Foot motions in manual material handling transfer tasks: a taxonomy and data from an automotive assembly plant

Ergonomic job analysis commonly applies static postural and biomechanical analysis tools to particular postures observed during manual material handling (MMH) tasks, usually focusing on the most extreme postures or those involving the highest loads. When these analyses are conducted prospectively using digital human models, accurate prediction of the foot placements is critical to realistic postural analyses. In automotive assembly jobs, workers frequently take several steps between task elements, for example, picking up a part at one location and moving to another location to place it on the vehicle. A detailed understanding of the influence of task type and task sequence on the stepping pattern is necessary to accurately predict the foot placements associated with MMH tasks. The current study examined the patterns of foot motions observed during automotive assembly tasks. Video data for 529 pickup and delivery tasks from 32 automotive assembly jobs were analysed. A minimum of five cycles was analysed for each task. The approach angle, departure angle, hand(s) used, manipulation height and patterns of footsteps were coded from the video. Object mass was identified from the job information sheet provided by the assembly plant. Three independent raters coded each video and demonstrated an intraclass correlation coefficient of 0.54 for identification of the configuration of the lower extremities during terminal stance. Based on an analysis of the distribution of stepping behaviours during object transitions (pickups or deliveries), a transition classification system (TRACS) was developed. TRACS uses a compact notation to quantify the sequence of steps associated with a MMH transition. Five TRACS behaviour groups accounted for over 90% of the transition stepping behaviours observed in the assembly plant. Approximately two-thirds (68.4%) of the object transfers observed were performed with only one foot in contact with the ground during the terminal posture. The results from this paper suggest that a predictive model for choosing a transition stepping behaviour, coupled with a model to scale the selected foot behaviours, is needed to facilitate accurate prospective ergonomic analyses. This study proposes a method for categorising the stepping patterns associated with MMH tasks. The influence of task type and task sequence on the stepping patterns observed during several automotive assembly tasks is discussed. For prospective postural analyses conducted using digital human models, accurate prediction of the foot placements is critical to realistic postural analyses.