Overall Task Effectiveness: a new Lean performance indicator in engineer-to-order environment

Purpose

The purpose of this paper is to propose a new Lean metric named Overall Task Effectiveness (OTE), which can help analyst to define target task times and to identify the hidden losses that account for most of the recorded time of manual assembly activities.

Design/methodology/approach

An alternative classification structure of the losses is developed to divide them in two classes. In the first one the losses that are external to the project order are included, and in the other one those due to inefficiencies directly ascribable to the project order are considered. Starting from this classification structure of the losses, a novel Lean metric, inspired from the well-known Overall Equipment Effectiveness (OEE), is developed to evaluate the effectiveness of a manual assembly task. A case study, which briefly explains the methodology and illustrates the capability of the corresponding metric, is provided.

Findings

This tool can be considered a suitable method to achieve simultaneously a dual purpose to establish time standards and to identify the hidden losses that account for most of the recorded time of manual assembly activities, estimating the impacts of potential corrective actions in terms of both efficiency and effectiveness.

Practical implications

OTE provides practitioners with an operative tool useful to highlight the points where the major inefficiencies take place in industries producing large complex items via manual assembly lines. Its practical application is demonstrated using a case study concerning a manufacturer of train wagons.

Originality/value

One distinctive, and contemporarily appealing, feature of OTE with respect to other analogous KPIs is that it provides a breakdown structure for process losses that simplifies the task of evaluating the current performances and, at the same time, individuates both the source of losses and the corresponding corrective actions.

Exploring element accumulation patterns of a metal excluder plant naturally colonizing a highly contaminated soil

This work investigates the element distribution in Silene paradoxa growing on the mine dump of Fenice Capanne (Tuscany, Italy). The accumulation of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in root apoplast and symplast and in shoot was assessed and compared to the levels of the same metals in the respective rizosphere soils, analyzing both the total and the phytoavailable fractions. Levels of As, Cu, Fe, Pb and Zn, were above toxicity thresholds in both soil and shoot samples. Inter- and intra-element correlations were analyzed in plant and soil using different statistical methods. Soil total and phytoavailable metal concentration were shown not to be dominant in determining metal accumulation by the plant, since no significant positive correlation was found between metal concentration in soils and plants. Moreover, results indicated that S. paradoxa was able to cope with the studied multi-metal contaminated soil excluding the elements from its tissues and preferentially accumulating them into the root compartment, thus suggesting this species as possible good candidate for phytostabilization purposes.

Cadmium phytoextraction potential of different Alyssum species

This work was planned for providing useful information about the possibility of using serpentine adapted plants for phytoextraction of cadmium, element scarcely represented in such metalliferous environment. To this aim, we investigated variation in cadmium tolerance, accumulation and translocation in three Alyssum plants with different phenotypes: Alyssum bertolonii, that is a serpentine endemic nickel hyperaccumulator, and two populations of Alyssum montanum, one adapted and one not adapted to serpentine soils. Plants were hydroponically cultivated in presence of increasing concentrations of CdSO(4) for two weeks. For the metal concentration used in the experiments, the three different Alyssum populations showed variation in cadmium tolerance, accumulation and content. The serpentine adapted population of A. montanum showed statistically higher cadmium tolerance and accumulation than A. bertolonii and the population of A. montanum not adapted to serpentine soil thus deserving to be investigated for phytoextraction purposes. Furthermore, as for the kinetic parameters of the cadmium uptake system, A. montanum serpentine population presented a low apparent K(m) value, suggesting a high affinity for this metal of its uptake system, whereas the V(max) values were not significantly different among the plants. Present data revealed metallicolous plants are also suitable for the phytoremediation of metals underrepresented in the environment of their initial origin. Nonetheless, field trials on real contaminated soils are essential.

Exploring the metal phytoremediation potential of three Populus alba L. clones using an in vitro screening

PURPOSE

This work was planned for providing a useful screening tool for the selection of Populus alba clones suitable for phytoremediation techniques. To this aim, we investigated variation in arsenic, cadmium, copper, and zinc tolerance, accumulation and translocation in three poplar clones through an in vitro screening. Poplars have been widely proposed for phytoremediation, as they are adaptable to grow on contaminated areas and able to accumulate metals. The investigation of possible differences among poplar clones in metal tolerance and accumulation deserves to be deeply studied and exploited for the selection of the more suitable tool for phytoremediation purposes.

METHODS

In vitro multiplied microshoots of a commercial and two autochthonous P. alba clones were subcultured on hormone-free WPM medium for 1 month and then transferred for 2 weeks onto media containing different concentrations of the metals investigated. At the end of the treatments, plantlets were sampled, weighed, and mineralised by wet ashing. Metal concentrations were determined by ICP-OES.

RESULTS

For the metal concentration used in the experiments, our clones of P. alba showed variation in metal tolerance, metal accumulation and content. The fast-growing commercial clone, even if rarely showing the highest plant metal concentration, displayed the highest metal content, suggesting biomass production as the key factor in evaluating the phytoextraction capacity of P. alba clones for the metals studied.

CONCLUSIONS

Data demonstrated that in vitro screening of cuttings represents a valuable way of assessing the ability of different poplar clones to take up, tolerate and survive metal stress.

Evolutionary lineages of nickel hyperaccumulation and systematics in European Alysseae (Brassicaceae): evidence from nrDNA sequence data

BACKGROUND AND AIMS

Nickel (Ni) hyperaccumulation is a rare form of physiological specialization shared by a small number of angiosperms growing on ultramafic soils. The evolutionary patterns of this feature among European members of tribe Alysseae (Brassicaceae) are investigated using a phylogenetic approach to assess relationships among Ni hyperaccumulators at the genus, species and below-species level.

METHODS

Internal transcribed spacer (ITS) sequences were generated for multiple accessions of Alysseae. Phylogenetic trees were obtained for the genera of the tribe and Alyssum sect. Odontarrhena. All accessions and additional herbarium material were tested for Ni hyperaccumulation with the dimethylglyoxime colorimetric method.

KEY RESULTS

Molecular data strongly support the poorly known hyperaccumulator endemic Leptoplax (Peltaria) emarginata as sister to hyperaccumulator species of Bornmuellera within Alysseae. This is contrary to current assumptions of affinity between L. emarginata and the non-hyperaccumulator Peltaria in Thlaspideae. The lineage Bornmuellera-Leptoplax is, in turn, sister to the two non-hyperaccumulator Mediterranean endemics Ptilotrichum rupestre and P. cyclocarpum. Low ITS sequence variation was found within the monophyletic Alyssum sect. Odontarrhena and especially in A. murale sensu lato. Nickel hyperaccumulation was not monophyletic in any of three main clades retrieved, each consisting of hyperaccumulators and non-hyperaccumulators of different geographical origin.

CONCLUSIONS

Nickel hyperaccumulation in Alysseae has a double origin, but it did not evolve in Thlaspideae. In Bornmuellera-Leptoplax it represents an early synapomorphy inherited from an ancestor shared with the calcicolous, sister clade of Mediterranean Ptilotrichum. In Alyssum sect. Odontarrhena it has multiple origins even within the three European clades recognized. Lack of geographical cohesion suggests that accumulation ability has been lost or gained over the different serpentine areas of south Europe through independent events of microevolutionary adaptation and selection. Genetic continuity and strong phenotypic plasticity in the A. murale complex call for a reduction of the number of Ni hyperaccumulator taxa formally recognized.

Naturally-assisted metal phytoextraction by Brassica carinata: role of root exudates

Due to relatively high chelant dosages and potential environmental risks it is necessary to explore different approaches in the remediation of metal-contaminated soils. The present study focussed on the removal of metals (As, Cd, Cu, Pb and Zn) from a multiple metal-contaminated soil by growing Brassica carinata plants in succession to spontaneous metallicolous populations of Pinus pinaster, Plantago lanceolata and Silene paradoxa. The results showed that the growth of the metallicolous populations increased the extractable metal levels in the soil, which resulted in a higher accumulation of metals in the above-ground parts of B. carinata. Root exudates of the three metallicolous species were analysed to elucidate their possible role in the enhanced metal availability. The presence of metals stimulated the exudation of organic and phenolic acids as well as flavonoids. It was suggested that root exudates played an important role in solubilising metals in soil and in favouring their uptake by roots.

High-level Zn and Cd tolerance in Silene paradoxa L. from a moderately Cd- and Zn-contaminated copper mine tailing

Cadmium and zinc tolerance were examined in populations of Silene paradoxa, one from uncontaminated calcareous soil (CVD) and one from a mine tailing (FC) (Cd<1-15 ppm, Zn 400-1300 ppm, pH 2-6). The mine population exhibited extremely high Zn and Cd tolerance levels, although the degrees of Cd and Zn enrichment relatively low at the population site. Cd and Zn hypertolerance in FC were associated with reduced rates of accumulation of these metals, both in roots and shoots (Cd), or exclusively in shoots (Zn). However, exclusion potentially explained only a minor part of the superior tolerance in FC. Cd hypertolerance in FC was associated with decreased, rather than enhanced phytochelatin accumulation. The remarkably high levels of Cd and Zn hypertolerance in FC might relate to the low soil pH, due to oxidation of sulphide minerals, and the absence of soil organic matter at the FC site.

Arsenate tolerance in Silene paradoxa does not rely on phytochelatin-dependent sequestration

Arsenate tolerance, As accumulation and As-induced phytochelatin accumulation were compared in populations of Silene paradoxa, one from a mine site enriched in As, Cu and Zn, the other from an uncontaminated site. The mine population was significantly more arsenate-tolerant. Arsenate uptake and root-to-shoot transport were slightly but significantly higher in the non-mine plants. The difference in uptake was quantitatively insufficient to explain the difference in tolerance between the populations. As accumulation in the roots was similar in both populations, but the mine plants accumulated much less phytochelatins than the non-mine plants. The mean phytochelatin chain length, however, was higher in the mine population, possibly due to a constitutively lower cellular glutathione level. It is argued that the mine plants must possess an arsenic detoxification mechanism other than arsenate reduction and subsequent phytochelatin-based sequestration. This alternative mechanism might explain at least some part of the superior tolerance in the mine plants.

Isolation and characterization of endophytic bacteria from the nickel hyperaccumulator plant Alyssum bertolonii

We report the isolation and characterization of endophytic bacteria, endemic to serpentine outcrops of Central Italy, from a nickel hyperaccumulator plant, Alyssum bertolonii Desv. (Brassicaceae). Eighty-three endophytic bacteria were isolated from roots, stems, and leaves of A. bertolonii and classified by restriction analysis of 16S rDNA (ARDRA) and partial 16S rDNA sequencing in 23 different taxonomic groups. All isolates were then screened for siderophore production and for resistance to heavy metals. One isolate representative of each ARDRA group was then tested for plant tissue colonization ability in sterile culture. Obtained results pointed out that, despite the high concentration of heavy metals present in its tissues, A. bertolonii harbors an endophytic bacterial flora showing a high genetic diversity as well as a high level of resistance to heavy metals that could potentially help plant growth and Ni hyperaccumulation.

Evidence for PSII donor-side damage and photoinhibition induced by cadmium treatment on rice (Oryza sativa L.)

The effects of cadmium (from 7.5 to 75 microM) on chloroplasts of rice were studied at the structural and biochemical level. Loss of pigments, reduction of thylakoids and decrease in oxygen evolution and Fv/Fm ratio occur in leaves following cadmium treatment. However, the amount of photosystem II reaction center proteins and that of its light harvesting complex is not affected, indicating that cadmium does not adversely influence the structural organization of this photosystem. In thylakoids isolated from cadmium-treated plants a loss in the capability to reduce 2,6-dichlorophenolindophenol is observed, which is partially restored if diphenylcarbazide is used as an electron donor, indicating that cadmium affects water splitting activity. In thylakoids isolated from control plants and treated with cadmium, diphenylcarbazide preserves most of the photosystem II activity lost after incubation with cadmium; most of the S(2) multiline electron paramagnetic resonance signal from the manganese cluster is lost, whereas the TyrD(+) and other signals are retained. Light-induced photosystem II damage, in vitro, is promoted by Cd-treatment as deduced from the mobility shift of the D1 protein observed by immunoblot.

Evolutionary dynamics of nickel hyperaccumulation in Alyssum revealed by its nrDNA analysis

•   Molecular phylogeny based on ribosomal internal transcribed spacer (ITS) sequences was studied to investigate the phyletic relationships among some nickel (Ni)-hyperaccumulating and nonhyperaccumulating species of the genus Alyssum in relation to their geographic distribution and Ni-hyperaccumulating phenotype. •   Thirty-seven samples belonging to 32 taxa were analysed by sequencing the polymerase chain reaction-amplified ITS region and performing neighbor joining, maximum parsimony and maximum likelihood phylogenetic analyses. •   The ITS region in the sampled species varied from 221 to 307 bp of ITS1 and from 194 to 251 bp of ITS2. A total of 765 characters was used to infer the phylogeny and the average nucleotide variation detected was 15.15%. •   Nickel-hyperaccumulation could have been lost or acquired independently more than once during the speciation of the genus. The geographical location of species could not be related to phylogenetic affinities.

Chloroplast genetic diversity and biogeography in the serpentine endemic Ni-hyperaccumulator Alyssum bertolonii

• Chloroplast microsatellites (cpSSR) were used to analyze the patterns of genetic variation within and among populations of the serpentine endemic, Alyssum bertolonii . • Thirty-five different chloroplast haplotypes were identified in 90 plants sampled from nine populations originating from the four disjunct northern-Italian serpentine regions where the species is found. • High levels of genetic diversity were found within each of the populations sampled. Analysis of Molecular Variance (AMOVA) showed high degrees of differentiation among both different populations of the same serpentine region and different regions (Φ _ST = 0.622, Φ _CT = 0.252, respectively). • The results indicated that: each population was established by few founders and then subsequently differentiated the existing chloroplast haplotypes; each population is a distinct genetic entity; and populations within the same serpentine region are more related than populations from different regions.

Characterization of nickel-resistant bacteria isolated from serpentine soil

In the present study, heterotrophic nickel-resistant bacteria were isolated and characterized from three different serpentine outcrops in central Italy populated by the nickel-hyperaccumulating plant Alyssum bertolonii. Bacteria were isolated from the rhizosphere of the plant and from soil portions at various distances from the plant. The proportion of nickel-resistant cfu was higher in proximity to the plant than in free soil. A total of 138 isolates was collected and grouped into 47 different operational taxonomic units (OTUs) by means of amplified ribosomal DNA restriction analysis (ARDRA) and into 25 heavy-metal resistant phenotypes. The phylogenetic position of strains belonging to 20 OTUs, representing more than the 70% of the total isolates, was determined by 16S rDNA sequencing. These analyses showed that the most represented genera in all three different outcrops were Pseudomonas and Streptomyces. Pseudomonas strains were found to be predominant in the plant rhizosphere, whereas Streptomyces strains were mainly present in the soil.

Genetic diversity of heavy metal-tolerant populations in Silene paradoxa L. (Caryophyllaceae): a chloroplast microsatellite analysis

Eight populations of Silene paradoxa L. (Caryophyllaceae) growing in copper mine deposits, in serpentine outcrops or in uncontaminated soil in central Italy were studied. Genetic diversity was estimated using five polymorphic chloroplast microsatellite loci (cpSSR), identifying 27 different chloroplast haplotypes. The effective number of alleles, the haplotypic diversity and a stepwise mutational model-based parameter (DSH2) were computed. The effective number of alleles observed within populations from copper mine deposits was 20% that of the serpentine neighbouring populations, suggesting the occurrence of a founder effect. Moreover, 13 of the 27 different haplotypes scored were exclusive to only one population, indicating genetic isolation for all tolerant populations. Even the copper-tolerant populations appeared to have evolved independently. Finally, analysis of molecular variance (AMOVA) of the cpSSR markers gave statistical significance to the grouping of populations according to their geographical location. This study demonstrates that cpSSR markers could be a useful complementary tool to isoenzymes or random amplified polymorphic DNA markers for elucidating the pattern of genetic differentiation in heavy metal-tolerant populations.

Genetic diversity and heavy metal tolerance in populations of Silene paradoxa L. (Caryophyllaceae): a random amplified polymorphic DNA analysis

Metal-contaminated sites can occur naturally in serpentine outcrops or as consequence of anthropogenic activities, such as mining deposits, aerial fallout from smelters and industrial processes. Serpentine outcrops are characterized by high levels of nickel, cobalt and chromium and present a typical vegetation which includes endemisms and plants which also live in uncontaminated soils. These latter metal-tolerant populations provide the opportunity to investigate the first steps in the differentiation of plant populations under severe selection pressure and to select plants to be used in the phytoremediation of industrially contaminated soils. In this report eight populations of Silene paradoxa L. (Caryophyllaceae) growing in copper mine deposits, in serpentine outcrops or in noncontaminated soil in central Italy, were analysed using random amplified polymorphic DNA (RAPD) markers to investigate the pattern of genetic variation. The genetic diversity observed in populations at copper mine deposits was found to be at least as high as that of the neighbouring serpentine populations. Analysis of molecular variance (AMOVA) of the RAPD markers gave high statistical significance to the groupings of populations according: (i) with their geographical location; and (ii) with the metals present in the soil of origin (copper vs. nickel), indicating that RAPD markers detected a polymorphism related to the soil contamination by copper. Finally, two RAPD bands exclusive to copper-tolerant populations were identified.

The effects of nickel, calcium and magnesium on the acid phosphatase activity of two Alyssum species

Root Surface acid phosphatase activity was assessed in seedlings of two species of Alyssum, one endemic to Tuscan serpentines (Alyssum bertolonii Desv.) and the other of wide occurrence (Alyssum saxatile L.), cultivated in solutions to which various concentrations of Ni²⁺ , Ca²⁺ and Mg²⁺ were added. Treatments were applied in two factorial experiments of type 2ⁿ . A concentration of 0.01 mM Ni²⁺ markedly stimulated phosphatase activity in A. bertolonii, but slightly decreased it in A. saxatile. Increased Ca²⁺ concentration stimulated enzyme activity in both species, hut in A. bertolonii the highest activity was obtained with low Ca²⁺ concentrations, whilst the opposite occured in A. saxatile. A. bertolonii instead required high Mg²⁺ concentrations to increase phosphatase activity significantly. The same concentrations were toxic to A. saxatile. In the serpentine species, favourable conditions for the increase of phosphatase activity were induced by a high Mg²⁺ /Ca²⁺ ratio, which also favoured dry mass production. Therefore it is possible that the increase of phosphatase activity might be an aspect of plant adaptation to serpentines.