Implementing lean practices in manufacturing SMEs: testing ‘critical success factors’ using Necessary Condition Analysis

Lean practices are known to increase operational performance. Previous research has identified critical success factors for implementing lean practices. This research aims to examine the extent to which success factors are critical for various degrees of lean practice implementation. Using multiple-respondent self-assessments from 33 Dutch manufacturing small and medium-sized enterprises (SMEs), we conducted a Necessary Condition Analysis. Our findings indicated that the criticality of success factors is progression dependent. In the initial stages of the lean journey, SMEs could improve their lean practices in a bottom-up manner through local factors such as a learning focus, improvement training and support congruence. When lean practices are more advanced, some company-wide factors must be present: top management support, a shared improvement vision and a supplier link. Our findings question the universality of success factors such as strategic involvement and indicate the need for a more dynamic model of lean implementation.     

Detection and analysis of triterpenic compounds in apple extracts

A new technique for the rapid detection and analysis of triterpenic compounds in apple extracts using HPLC was developed and validated. The main advantage of this technique is the short duration of the analysis – this makes this technique superior to others currently applied for the routine HPLC analysis of triterpenic compounds. The developed, optimized, and validated technique was used for the evaluation of triterpenic compounds in samples of different cultivars of apples, their peels, and flesh. In total, four triterpenic compounds were isolated and identified. Ursolic acid was the dominant compound in all the tested apple samples. The highest amounts of triterpenic compounds were detected in the peels of the ‘Lodel’ apple cultivar, and thus apples of this cultivar may be potentially useful for the isolation of individual compounds and the production of functional food and dietary supplements.     

Automated gaze-based mind wandering detection during computerized learning in classrooms

We investigate the use of commercial off-the-shelf (COTS) eye-trackers to automatically detect mind wandering—a phenomenon involving a shift in attention from task-related to task-unrelated thoughts—during computerized learning. Study 1 (N?=?135 high-school students) tested the feasibility of COTS eye tracking while students learn biology with an intelligent tutoring system called GuruTutor in their classroom. We could successfully track eye gaze in 75% (both eyes tracked) and 95% (one eye tracked) of the cases for 85% of the sessions where gaze was successfully recorded. In Study 2, we used this data to build automated student-independent detectors of mind wandering, obtaining accuracies (mind wandering F₁?=?0.59) substantially better than chance (F₁?=?0.24). Study 3 investigated context-generalizability of mind wandering detectors, finding that models trained on data collected in a controlled laboratory more successfully generalized to the classroom than the reverse. Study 4 investigated gaze- and video- based mind wandering detection, finding that gaze-based detection was superior and multimodal detection yielded an improvement in limited circumstances. We tested live mind wandering detection on a new sample of 39 students in Study 5 and found that detection accuracy (mind wandering F₁?=?0.40) was considerably above chance (F1?=?0.24), albeit lower than offline detection accuracy from Study 1 (F₁?=?0.59), a finding attributable to handling of missing data. We discuss our next steps towards developing gaze-based attention-aware learning technologies to increase engagement and learning by combating mind wandering in classroom contexts.

     

Dissolution of softwood kraft pulps by direct derivatization in lithium chloride/N,N‐dimethylacetamide

A method for the characterization of the molar mass distributions (MMDs) of softwood kraft pulps dissolved in 0.5% lithium chloride (LiCl)/N,N‐dimethylacetamide (DMAc) by size exclusion chromatography is presented. The method is based on derivatization with ethyl isocyanate and the dissolution of samples in 8% LiCl/DMAc. In this study, the derivatization of hardwood kraft pulps did not influence the MMD. In the case of softwood pulps, however, the derivatization decreased the proportion of the high‐molecular‐mass material and increased the proportion of the low‐molecular‐mass material, which resulted in a distribution similar to the MMD of a hardwood kraft pulp. The results suggest that associations between hemicellulose and cellulose in the softwood kraft pulp were ruptured during derivatization. This led to a more correct estimation of the MMD of derivatized softwood kraft pulps than obtained by the dissolution of nonderivatized samples. This new method offers several advantages over derivatization with phenyl isocyanate: a precipitation step is not necessary, it is possible to follow the lignin distribution in the samples, and the method allows very high levels of dissolution of softwood kraft pulps up to a κ number of around 50. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 424–431, 2004     

Catalytic properties of oxide nanoparticles applied in gas sensors

A series of gas sensing layers based on indium oxide doped with gold were prepared by using the aerosol technology for deposition as the active contact layer in a metal oxide semiconductor capacitive device. The interaction between the measured species and the insulator surface was quantified as the voltage changes at a constant capacitance of the device. The sensor properties were investigated in the presence of H₂, CO, NH₃, NO, NO₂ and C₃H₆ at temperatures between 100–400 °C. Significant differences in the morphology of the layer and its sensitivity were noted for different preparation methods and different gas environments.     

Artificial Light Regulation of an Allosteric Bienzyme Complex by a Photosensitive Ligand

The artificial regulation of proteins by light is an emerging subdiscipline of synthetic biology. Here, we used this concept to photocontrol both catalysis and allostery within the heterodimeric enzyme complex imidazole glycerol phosphate synthase (ImGP‐S). ImGP‐S consists of the cyclase subunit HisF and the glutaminase subunit HisH, which is allosterically stimulated by substrate binding to HisF. We show that a light‐sensitive diarylethene (1,2‐dithienylethene, DTE)‐based competitive inhibitor in its ring‐open state binds with low micromolar affinity to the cyclase subunit and displaces its substrate from the active site. As a consequence, catalysis by HisF and allosteric stimulation of HisH are impaired. Following UV‐light irradiation, the DTE ligand adopts its ring‐closed state and loses affinity for HisF, restoring activity and allostery. Our approach allows for the switching of ImGP‐S activity and allostery during catalysis and appears to be generally applicable for the light regulation of other multienzyme complexes.     

Waterborne rotavirus: A risk assessment

A risk assessment approach was used to estimate the public health impacts from exposure to human rotavirus in drinking and recreational waters. Rotavirus is the major cause of viral gastroenteritis worldwide and several waterborne outbreaks have been documented. This results in a significant economic impact on society in terms of direct medical costs, loss of work, quality of life and mortality. The virus is common in domestic wastewater and polluted surface waters. Dose-response data in human adult volunteers indicate that it is the most infective of all the enteric viruses, and this was used to develop a microbial risk assessment model to estimate daily and yearly risks of infection, morbidity and mortality for exposure via drinking and recreational waters using existing information on the occurrence of rotavirus. The disease is most severe for the very young, the elderly, and the immunocompromised. Case fatality rates in the United States are 0.01% in the general population, 1% in the elderly, and up to 50% in the immunocompromised. Analysis indicates that significant risks of disease (5 × 10⁻¹−2.45 × 10⁻³) could result for drinking and recreational waters in which rotavirus has been detected. The major limitation in assessing the risks of waterborne rotaviral infections at present is the lack of data on its occurrence in water and the potential for human exposure.