Speciation of PM10 sources of airborne nonferrous metals within the 3-km zone of lead/zinc smelters

The purpose of this study was to estimate the speciation of PM10 sources of airborne Pb, Zn, and Cd metals (PM10 is an aerosol standard of aerodynamic diameter less than 10 microm.) in the atmosphere of a 3 km zone surrounding lead/zinc facilities in operation for a century. Many powdered samples were collected in stacks of working units (grilling, furnace, and refinery), outdoor storages (ores, recycled materials), surrounding waste slag (4 Mt), and polluted topsoils (3 km). PM10 samples were generated from the raw powders by using artificial resuspension and collection devices. The bulk PM10 multielemental analyses were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The proportions in mass of Pb (50%), Zn (40%), and Cd (1%) contents and associated metals (traces) reach the proportions of corresponding raw powdered samples of ores, recycled materials, and fumesize emissions of plants without specific enrichment. In contrast, Pb (8%) and Zn (15%) contents of PM10 of slag deposit were found to be markedly higher than those of raw dust, Pb (4%), and Zn (9%), respectively. In the same way, Pb (0.18%), Zn (0.20%), and Cd (0.004%) were enriched by 1.7, 2.1, and 2.3 times, respectively, in PM10 as compared with raw top-soil corresponding values. X-ray wavelength dispersive electron-microprobe (EM-WDS) microanalysis did not indicate well-defined phases or simple stoichiometries of all the PM10 samples atthe level of the spatial resolution (1 microm3). X-ray photoelectron spectroscopy (XPS) indicated that minor elements such as Cd, Hg, and C are more concentrated on the particle surface than in the bulk of PM10 generated by the smelting processes. (XPS) provided also the average speciation of the surface of PM10; Pb is mainly represented as PbSO4, Zn as ZnS, and Cd as CdS or CdSO4, and small amounts of coke were also detected. The speciation of bulk PM10 crystallized compounds was deduced from XRD diffractograms with a raw estimation of the relative quantities. PbS and ZnS were found to be the major phases in PM10 generated by the smelting facilities with PbSO4, PbSO4 x PbO, PbSO4 x 4PbO, Pb metal, and ZnO as minor phases. The slag waste PM10 was found to contain some amounts of PbCO3, PbSO4 x PbO, and ZnFe2O4 phases. The large heterogeneity at the level of the individual particle generates severe overlap of chemical information even at the microm scale using electron microprobe (WDS) and Raman microprobe techniques. Fortunately, scanning Raman microspectrometry combined with SIMPle-to-use Interactive Self-modeling Mixture Analysis (SIMPLISMA) performed the PM10 speciation at the level of individual particles. The speciation of major Pb, Zn, and Cd compounds of PM10 stack emissions and wind blown dust of ores and recycled materials were found to be PbSO4, PbSO4 x PbO, PbSO4 x 4PbO, PbO, metallic Pb, ZnS, ZnO, and CdS. The PM10 dust of slag waste was found to contain PbCO3, Pb(OH)2 x 2PbCO3, PbSO4 x PbO, and ZnS, while PM10-bound Pb, Zn of the top-soils contain Pb5(PO4)3Cl, ZnFe2O4 as well as Pb(II) and Zn(II) compounds adsorbed on Fe(III) oxides and in association with clays.     

Diversity in Fungal Intermolecular Phenol Coupling of Polyketides: Regioselective Laccase-Based Systems

Polyketides form a structurally diverse and pharmaceutically important class of secondary metabolites. Both diversity and biological activity are largely facilitated by post-polyketide synthase tailoring including methylation, oxidation, reduction, glycosylation, and dimerization. Cytochrome P450 enzymes (CYPs), flavin-dependent monooxygenases (FMOs), and laccases are known to catalyze phenol coupling in the biosynthesis of polyketide dimers. Polyketide homodimers resulting from enzyme catalysis are often formed in a highly regio- and stereoselective manner, in contrast to analogous nonenzymatic dimerization. Although it is known that CYPs and FMOs are capable of selectively generating one of several putative isomers, hitherto described laccases depend on auxiliary proteins to achieve similar selectivity. Herein, regioselective phenol coupling catalyzed by a fungal laccase is demonstrated. The heterologously produced Av-VirL from Aspergillus viridinutans selectively generated the 6,6′-homodimer of (R)-semivioxanthin. Genome analysis is used to show that laccase-based phenol-coupling systems are widespread in fungi. Homologues of Av-VirL were identified in the putative biosynthetic gene clusters of vioxanthin, xanthomegnin, and xanthoepocin, and of the perylenequinones hypocrellin A, elsinochrome A, and cercosporin. These findings show that laccases are capable of selective phenol coupling in the absence of auxiliary proteins.     

MINAS: multiclass learning algorithm for novelty detection in data streams

Data stream mining is an emergent research area that aims at extracting knowledge from large amounts of continuously generated data. Novelty detection (ND) is a classification task that assesses if one or a set of examples differ significantly from the previously seen examples. This is an important task for data stream, as new concepts may appear, disappear or evolve over time. Most of the works found in the ND literature presents it as a binary classification task. In several data stream real life problems, ND must be treated as a multiclass task, in which, the known concept is composed by one or more classes and different new classes may appear. This work proposes MINAS, an algorithm for ND in data streams. MINAS deals with ND as a multiclass task. In the initial training phase, MINAS builds a decision model based on a labeled data set. In the online phase, new examples are classified using this model, or marked as unknown. Groups of unknown examples can be used later to create valid novelty patterns (NP), which are added to the current model. The decision model is updated as new data come over the stream in order to reflect changes in the known classes and allow the addition of NP. This work also presents a set of experiments carried out comparing MINAS and the main novelty detection algorithms found in the literature, using artificial and real data sets. The experimental results show the potential of the proposed algorithm.     

Chemotaxis of larval soybean cyst nematode,Heterodera glycines Race 3, to root leachates and ions

Second-stage larvae of the soybean cyst nematodeHeterodera glycines Race 3 were attracted in an in vitro bioassay to pooled leachates of soybean roots that were expressed as root gram-hours (1 g of root/hr/vol). Their responses were dosage dependent with maximal attraction to a 5 root g-hr/ml source. Optimal bioassay conditions used 24 hr for gradient formation and 1.5 hr for larval movement. Individual plants produced leachate with little variation in biological activity. Production was constant for five days of preparation. The attractive activity of root leachate declined with storage at 4 °C and heating over 30 °C, but loss of activity was reduced by freezing. Extraction and Sep-Pak fractionation indicated that the attractions(s) was water-soluble. Larvae were attracted also to several ionic solutions.     

Maximum-Likelihood Estimation of the Parameters of a Four-Parameter Generalized Gamma Population from Complete and Censored Samples

Consider the four-parameter generalized Gamma population with location parameter c, scale parameter a, shape/power parameter b, and power parameter p (shape parameter d = bp) and probability density function f(x; c, a, b, p) = p(x — c) ^bp–1 exp {–[(x – c)/a] ^p }/a ^bp Γ(b), where a, b, p > 0 and x ≥ c ≥ 0. The likelihood equations for parameter estimation are obtained by equating to zero the first partial derivatives, with respect to each of the four parameters, of the natural logarithm of the likelihood function for a complete or censored sample. The asymptotic variances and covariances of the maximum-likelihood estimators are found by inverting the information matrix, whose components are the limits, as the sample size n → ∞, of the negatives of the expected values of the second partial derivatives of the likelihood function with respect to the parameters. The likelihood equations cannot be solved explicitly, but an iterative procedure for solving them on an electronic computer is described. The results of applying this procedure to samples from Gamma, Weibull, and half-normal populations are tabulated, as are the asymptotic variances and covariances of the maximum-likelihood estimators.     

Cutting optimization with variable-sized stock and inventory status data

Many production environments require economical cutting of one-dimensional items according to bills of materials from objects of several standard lengths. However, even with optimized cutting substantial trim loss may occur. This trim loss should not be regarded as waste. It is returned to store and can be reused in future optimizations. Optimization of packing linear items into standard lengths is presented for items that cannot be packed into available lengths from inventory status data. The core of the proposed optimization tackles the variablesized bin packing problem (VBPP). The article presents a hybrid genetic algorithm that packs items into both available objects from the inventory and variablesized objects from the stock. The algorithm tries to minimize waste. Large trimloss items are returned as remnants to the inventory for subsequent optimizations.     

Two-dimensional XD-GRASP provides better image quality than conventional 2D cardiac cine MRI for patients who cannot suspend respiration

Objectives

Residual respiratory motion degrades image quality in conventional cardiac cine MRI (CCMRI). We evaluated whether a free-breathing (FB) radial imaging CCMRI sequence with compressed sensing reconstruction [extradimensional (e.g. cardiac and respiratory phases) golden-angle radial sparse parallel, or XD-GRASP] could provide better image quality than a conventional Cartesian breath-held (BH) sequence in an unselected population of patients undergoing clinical CCMRI.

Materials and methods

One hundred one patients who underwent BH and FB imaging in a midventricular short-axis plane at a matching location were included. Visual and quantitative image analysis was performed by two blinded experienced readers, using a five-point qualitative scale to score overall image quality and visual signal-to-noise ratio (SNR) grade, with measures of noise and sharpness. End-diastolic and end-systolic left ventricular areas were also measured and compared for both BH and FB images.

Results

Image quality was generally better with the BH cines (overall quality grade for BH vs FB images 4 vs 2.9, p < 0.001; noise 0.06 vs 0.08 p < 0.001; SNR grade 4.1 vs 3, p < 0.001), except for sharpness (p = 0.48). There were no significant differences between BH and FB images regarding end-diastolic or end-systolic areas (p = 0.35 and p = 0.12). Eighteen of the 101 patients had poor BH image quality (grade 1 or 2). In this subgroup, the quality of the FB images was better (p = 0.0032), as was the SNR grade (p = 0.003), but there were no significant differences regarding noise and sharpness (p = 0.45 and p = 0.47).

Conclusion

Although FB XD-GRASP CCMRI was visually inferior to conventional BH CCMRI in general, it provided improved image quality in the subgroup of patients with respiratory-motion-induced artifacts on BH images.

     

Long-term failure of transversely loaded glass/iPP

Herein, temperature-dependent long-term behavior of polypropylene and its transversely loaded unidirectional glass fiber reinforced composite is investigated and a lifetime prediction method is proposed, which is based on the observed long-term failure mechanisms. Furthermore, the effect of cooling rate during processing on the time-dependent behavior is addressed. The composite is revealed to exhibit multiple molecular deformation mechanisms, similar to neat polypropylene, which is modeled using the Ree–Eyring approach. Failure kinetics under constant-strain-rate and creep tests are found to be identical and switching from creep to cyclic loading decelerates the failure, which are signs of plasticity-controlled failure. Hence, lifetime is predicted well by using a lifetime prediction methodology for the plasticity-controlled failure which combines the Ree–Eyring approach and the concept of critical strain. A change in the cooling rate alters the deformation and failure kinetics: lower cooling rates promote embrittlement.     

Use of X-ray tomography to study the porosity and morphology of granules

X-ray computed tomography (XRCT) is a technique that uses X-ray images to reconstruct the internal microstructure of objects. Known as a CAT scan in medicine, it has found wide application for whole-body and partial-body imaging of hard tissues (e.g., bone). A modern tabletop XRCT system with a resolution of about 4 μm was used to characterize some pharmaceutical granules. Total porosity, pore size distribution, and geometric structure of pores in granules produced using different conditions and materials were studied. The results were compared to data obtained from mercury porosimetry. It was found that while XRCT is less precise in the determination of total porosity in comparison to mercury porosimetry, it provides detailed morphological information such as pore shape, spatial distribution, and connectivity. The method is nondestructive and accurate down to the resolution of the instrument.Tomographic images show that the pore network of individual granules comprises relatively large cavities connected by narrow pore necks. The major structural difference between granules produced at different conditions of compaction and shear is a reduction in the pore neck diameter; the cavity size is relatively insensitive to these conditions. Comparison of pore size distributions determined from tomographic images and mercury porosimetry indicates that mercury intrusion measures the pore neck size distribution, while tomography measures the true size distribution of pores ca. 4 μm or larger (the instrument resolution).