Push/Pull Risk Factors at Workstations: A Case‐Control Study of Mexican Industrial Workers

The objective of this study was to quantify and assess whether push/pull tasks in the workplace are risk factors for lower back pain etiology. A case‐control study was conducted of 231 industrial workers 18–55 years old who were insured by the Mexican Social Security Institute (MSSI) in the Guadalajara Metropolitan Area of Jalisco, Mexico. Exposure was evaluated via a questionnaire. Multivariate analysis using conditional logistic regression showed risks for push/pull tasks (odds ratio = 5.7, 95% confidence interval, 1.4–23.1) adjusted for lifting, carrying, and driving work. The fraction attributable to push/pull tasks was 0.58, suggesting that the risk of developing lumbar spondyloarthrosis might be reduced by 58% with ergonomic redesign for pushing and pulling tasks at workstations. Additional research is needed to confirm this relationship and will ideally incorporate a greater number of subjects to assure detailed analyses of exposure categories and facilitate new comparisons with the results of the present study. © 2012Wiley Periodicals, Inc.     

Nucleation and growth of carbon black particles during thermal decomposition of benzene

The authors determined the mechanism of carbon black formation during the thermal decomposition of benzene diluted with a stream of nitrogen. The kinetics study of nucleation and growth of particles led them to the following conclusions: The initial hydrocarbon is transformed by a gas phase reaction into macromolecules. The partial pressure of the macromolecules increases with reaction time until a supersaturation is high enough to induce condensation of macromolecules into droplets. The formation of liquid nuclei eliminates the supersaturation, and the formation of additional liquid nuclei becomes impossible. The macromolecules which continue to be formed maintain the nuclei growth. The liquid droplets are pyrolysed into a solid material. A statistical study of the distribution curves of the particle diameters indicates that the growth rate of each particle is proportional to its diameter.     

Need to Meet Investment Goals? Track Synthetic Indexes with the SDDP Method

Computational Economics - This work presents a novel application of the Stochastic Dual Dynamic Problem (SDDP) to large-scale asset allocation. We construct a model that delivers allocation...     

Quantitative analysis of morphological changes in yeast colonies growing on solid medium: the eccentricity and Fourier indices

The colony shape of four yeast species growing on agar medium was measured for 116 days by image analysis. Initially, all the colonies are circular, with regular edges. The loss of circularity can be quantitatively estimated by the eccentricity index, E_i, calculated as the ratio between their orthogonal vertical and horizontal diameters. E_i can increase from 1 (complete circularity) to a maximum of 1.17–1.30, depending on the species. One colony inhibits its neighbour only when it has reached a threshold area. Then, E_i of the inhibited colony increases proportionally to the area of the inhibitory colony. The initial distance between colonies affects those threshold values but not the proportionality, E_i/area; this inhibition affects the shape but not the total surface of the colony. The appearance of irregularities in the edges is associated, in all the species, not with age but with nutrient exhaustion. The edge irregularity can be quantified by the Fourier index, F_i, calculated by the minimum number of Fourier coefficients that are needed to describe the colony contour with 99% fitness. An ad hoc function has been developed in Matlab v. 7.0 to automate the computation of the Fourier coefficients. In young colonies, F_i has a value between 2 (circumference) and 3 (ellipse). These values are maintained in mature colonies of Debaryomyces, but can reach values up to 14 in Saccharomyces. All the species studied showed the inhibition of growth in facing colony edges, but only three species showed edge irregularities associated with substrate exhaustion. Copyright © 2014 John Wiley & Sons, Ltd.     

SHRINKAGE OF DATES (Phoenix Dactilyfera L.) DURING DRYING

In this paper the shrinkage of Dates (Phoenix dactilyfera L.) during drying was observed. Samples were dried in a convective tray dryer under three different conditions (60°C-11.1%RH, 70°C-7.2%RH and 80°C-4.7%RH) and three different air velocities (0.5m/s, l.0m/s and 1.5m/s). Sample shrinkage was directly (using a caliper) and indirectly measured (snapshot area measured). The indirect manner shows a higher precision. The geometry applied in the shrinkage solution proved that the ellipsoidal geometry of the dates, may be successfully approached to a cylinder. Three mathematical models developed by Suzuki et al. (1976) were applied to correlate the dates surface to its moisture content. The core model presented the best fit to the experimental data.     

Characterizing inorganic crystals grown on organic self‐assembled bilayers with scanning probe and electron microscopies

Combined microscopy techniques are used to establish the usability of phosphonic acid layers as promoters of hydroxyapatite (HAp) growth. Using spread coating, octadecylphosphonic acid (OPA) self‐assembled bilayers are delivered to the thin natural oxide layer of a titanium film surface with no prior treatment. These bilayers aggregate two major advantages of phosphonic moieties to titanium surfaces: nucleation of hydroxyapatite crystals from ionic solution and affinity for both titanium oxide surface and HAp crystals. The functionalized substrates and bare titanium (control) samples are immersed in an aqueous solution containing calcium and phosphorus ions. Over a 4‐week immersion time, OPA‐functionalized substrates present numerous large agglomerates of inorganic crystals, in contrast to control samples, with no significant amount of deposits. Initial sample characterization was performed with atomic force microscopy (AFM). Compositional and structural characterization of these agglomerates (using TEM, EDS, and electron diffraction), revealed that they are indeed HAp, the main component of the inorganic bone matrix. Microsc. Res. Tech. 76:1278–1283, 2013. © 2013 Wiley Periodicals, Inc.     

Thermogravimetric study of thermal decontamination of soils polluted by hexachlorobenzene, 4-chlorobiphenyl, naphthalene, or n-decane.

To determine decontamination behavior as affected by temperature, shallow beds of a clay-rich, a calcerous, and a sedimentary soil, artificially polluted with hexachlorobenzene, 4-chlorobiphenyl, naphthalene, or n-decane, were separately heated at 5 degrees C min-1 in a thermogravimetric analyzer. Temperatures for deep cleaning of the calcerous and the sedimentary soil increased with increasing boiling point (bp) of the aromatic contaminants, but removal efficiencies still approached 100% well below the bp. Decontamination rates were therefore modelled according to a pollutant evaporation-diffusion transport model. For the calcerous and sedimentary soils, this model reasonably correlated removal of roughly the first 2/3 of the naphthalene, but gave only fair predictions for hexachlorobenzene and 4-chlorobiphenyl. It was necessary to heat the clay soil above the aromatics bp to achieve high decontamination efficiencies. Weight loss data imply that for temperatures from near ambient to as much as 150 degrees C, interactions of each aromatic with the clay soil, or its decomposition products, result in lower net volatilization of the contaminated vs. neat clay. A similar effect was observed in heating calcerous soil polluted with hexachlorobenzene from near ambient to about 140 degrees C. Decontamination mechanisms remain to be established, although the higher temperatures needed to remove aromatics from the clay may reflect a more prominent role for surface desorption than evaporation. This would be consistent with our estimates that the clay can accommodate all of the initial pollutant loadings within a single surface monolayer, whereas the calcerous and sedimentary soils cannot.     

Organic–inorganic hybrid materials derived from epoxy resin and polysiloxanes: Synthesis and characterization

In this study, hybrid materials based on epoxy resin were prepared as transparent self‐supported films by a sol–gel process. 4,4′‐Diaminodiphenylmethane or oligomeric epoxy resin were used as precursors, which were conveniently functionalized with trialkoxysilanes as end‐groups. The effect of the introduction of poly (dimethylsiloxane) was also investigated. The hybrid films showed good thermal stability, a nondefined glass transition temperature, and a dense morphology without phase segregation. The tendency to a flat surface could be observed by atomic force microscopy. The hybrid films also showed good performance as coatings for glass plates, with an improved hydrophobic character in comparison to neat epoxy resin. POLYM. ENG. SCI., 48:141–148, 2008. © 2007 Society of Plastics Engineers     

Effects of different solvents on total phenolic and total anthocyanin contents of Clitoria ternatea L. petal and their anti-cholesterol oxidation capabilities

Clitoria ternatea (CT) petals have a high content of polyphenolic compounds, including anthocyanins, which protect against lipid oxidation. This research evaluated total phenolic content, total anthocyanin content and antioxidant activity of CT extracts obtained using distilled water, methanol, and/or water-methanol combination (1:1) solvents after 6, 12 and 24 h soaking times. The predominant bioactive compounds of CT petals were kaempferol 3-neohesperidoside (462.63 mg per 100 g), caffeoylmalic acid (137.59 mg per 100 g), and kaempferol 3-(2G-rhamnosylrutinoside) (129.28 mg per 100 g). The capacity of each solvent-type extract obtained from 6 h soaking time to inhibit cholesterol oxidation was determined after 24 and 48 h in an emulsion model. At 6 h soaking time, the combination-solvent yielded an extract with the highest anthocyanin content (63.9 μg mL⁻¹) and inhibited 89.8% of 7-ketocholesterol production in emulsion, compared to the control. This study demonstrated that CT petal extracts can enhance health benefits and lengthen shelf life of emulsion-type products.