Advanced manufacturing technology and work design: Towards a theoretical framework

This paper introduces a theoretical framework to guide research into the psychological effects of advanced manufacturing technology (AMT) on shopfloor operators. The framework has two main aspects. First, based on the emerging literature on the job content implications of AMT, it identifies four key constructs, namely: control, cognitive demand, production responsibility and social interaction. Second, by drawing on the more established job design, stress and related literatures, it predicts how these independent variables differentially affect system performance, job-related strain and job satisfaction. The wider implications and limitations of the theoretical framework are discussed.     

Effect of light Sphagnum peat on odour formation in the early stages of biowaste composting

In the present study, we investigated the effects of two bulking materials, Sphagnum peat and pine wood chips, on the early stages of biowaste composting in two pilot-scale processes. Emphasis was placed on studying the formation conditions of malodorous compost gases in the initial phases of the processes. The results showed that gas emission leaving an open windrow and a closed drum composting system contained elevated concentrations of fermentative microbial metabolites when acid Sphagnum peat (pH 3.2) was used as a bulking material. Moreover, the gas emission of the peat amended drum composter contained a high concentration of odour (up to 450,000 ou m^?3 of air). The highest odour values in the outlet gas of peat amended composts coincided with the elevated concentrations of volatile organic compounds such as acetoin and buthanedion. We conclude that the acidifying qualities of composting substrates or bulking material may intensify odour emission from biowaste composts and prolong the early stages of the composting process.     

Chemical oxidation of tetrachloroethene in a fractured saprolite/bedrock aquifer

Two chemical oxidizers, Fenton's Reagent (FR) and sodium permanganate (NaMnO₄), were used to remediate groundwater contaminated by tetrachloroethene (PCE) in a fractured saprolite and bedrock aquifer in Rockville, Maryland. Initial PCE concentrations ranged from 11 to 25,000 μg/L, averaging 8,684 μg/L in March 2000. A total of 28,256 pounds of hydrogen peroxide (as 35 percent solution) and iron catalyst were injected during the FR treatment program. The FR failed to achieve the desired clean‐up goal, after which 11,114 pounds of NaMnO₄ (as 40 percent solution) were diluted to a 20 percent solution and injected into the aquifer. An additional 855 pounds of dilute NaMnO₄ was later injected, which ultimately reduced the original PCE mass by an estimated 95 percent through November 2001. © 2003 Wiley Periodicals, Inc.     

Hydrolytic and enzymatic degradation of poly(γ-glutamic acid) hydrogels and their application in slow-release systems for proteins

The hydrolytic and enzymatic degradation of newly developed hydrogels, produced by cross-linking purified poly(-glutamic acid) (PGA) with dihaloalkane compounds, was studied and is reported in this paper. Analysis of hydrolysis of the hydrogel as a function of pH indicated that the hydrolysis occurred slowly at neutral pH, but fast in both acidic and alkaline solutions, while the polymer could be hydrolyzed rapidly only in acidic solutions. The ester bonds were more sensitive to hydrolysis than peptide bonds. The biodegradability of the hydrogel and polymer was further confirmed when enzymatic degradation was studied by three enzymes (cathepsin B, pronase E, and trypsin), which were able to cleave both ester and peptide bonds gradually. A slow-release system for porcine somatotropin (pST) formed by using the hydrogel as matrix to entrap the hormone was evaluatedin vitro andin vivo. Results demonstrated that the hydrogel was able to release the hormone for a period of 20–30 days and indicated its potential application in slow-release systems for bioactive materials, especially macromolecules, such as peptides and proteins.     

Improving the Rheological and Mechanical Properties of Recycled PET Modified by Macromolecular Chain Extenders Synthesized by Controlled Radical Polymerization

In this work, a series of reactive copolymers of glycidyl methacrylate (G), styrene (S) and acrylonitrile (AN), were synthesized through reversible addition-fragmentation chain transfer polymerization and evaluated as macromolecular chain extenders in reactive extrusion of recycled poly(ethylene terephthalate) (rPET). The results obtained indicate that the addition of the reactive copolymers as chain extenders modifies the chain conformation in rPET causing low crystallization rate and low crystallinity. The physical and rheological properties (melt flow and intrinsic viscosity) of chain-extended rPET improved, rendering better processability. rPET modified with polymeric chain extenders shows improved rheological properties (complex viscosity, storage and loss modulus) and also displays higher elongation at break and impact properties as the GMA content in the chain extenders increase.