Assessment of DNA damage in coal open-cast mining workers using the cytokinesis-blocked micronucleus test and the comet assay

Coal mining is one of the most important causes of environmental pollution, as large quantities of coal dust particles are emitted. Colombia-South America has large natural coal reserves and “El Cerrejón” is the world's largest open-cast mine located in the northern department of Guajira. The aim of the present study was to evaluate genotoxic effects in a population exposed to coal residues from the open-cast mine “El Cerrejón”. 100 exposed workers and 100 non-exposed control individuals were included in this study. The exposed group was divided according to different mining area activities: (i). Transport of extracted coal, (ii). Equipment field maintenance, (iii). Coal stripping and, (iv). Coal embarking. Blood samples were taken to investigate biomarkers of genotoxicity, specifically, primary DNA damage as damage index (DI), tail length and% of tail DNA using the Comet assay (alkaline version) and chromosome damage as micronucleus (MN) frequency in lymphocytes. Both biomarkers showed statistically significantly higher values in the exposed group compared to the non-exposed control group. No difference was observed between the exposed groups executing different mining activities. These results indicate that exposure to coal mining residues may result in an increased genotoxic exposure in coal mining workers. We did not find a correlation between age, alcohol consumption and service time with the biomarkers of genotoxicity. Our results are the first data of genotoxic effects induced by coal mining exposure in Colombia, and thus, contribute to the exploration of test batteries use for monitoring of exposed populations and may stimulate designing control, hygiene and prevention strategies for occupational health risk assessment in developing countries.     

Crosslinking of polypropylene–polyethylene blends by peroxide and the effect of pentaerythritol tetrallyl ether

Crosslinking of polypropylene–polyethylene (PP-PE) blends involving 10, 20, 30, 40, 50, 60, 70, 80, and 90% of PP with dicumylperoxide (DCP) or tert-butyl perbenzoate (TBPB) and in the presence of coagent pentaerythritol tetrallyl ether (PETA) was investigated at 180°C. It was found that at lower concentrations of peroxide alone (e.g., 2.5% of DCP) only PE component is crosslinked in all compositions of PP-PE blends. In the crosslinking of PP-PE 50:50 with 4% of TBPB, insoluble gel was obtained, which contained 13% PP and 87% PE. If 2% PETA was also used, the portion of PP in gel increased to 39%; the total yield of gel in PP-PE blend increased from 50 to 70%. The lower crosslinking efficiency of coagent PETA in the PP-PE blends compared with PP alone is associated with better solubility of the coagent in the PE phase in contrast to the PP phase. The coagent does not particularly raise the crosslinking efficiency of peroxide in PE, but increases it in the PP phase. A remarkable decrease in melting temperature and temperature of crystallization of both polymer components depending on peroxide concentration was found by calorimetric measurements.     

Laterally chromatically dispersed, spectrally encoded interferometer

We present a single-shot line sensor based on spectral interferometry. Light of a broadband laser source is chromatically dispersed by a grating and focused onto a line on the surface such that each focal point on this line is formed by another wavelength. The entire height profile is obtained by applying a phase evaluation algorithm to the registered interference signal, followed by a model-based approach. The sensor concept is finally verified by experimental results.     

Chemiluminescence and thermo-oxidation stability of poly(2,6-dimethyl-p-phenylene ether) in blends with polystyrene and polybutadiene

It has been ascertained that chemiluminescence-time curves for samples of poly(2,6-dimethyl-p-phenylene ether) blended with high-impact polystyrene containing polybutadiene yield a very reproducible pattern even at a temperature of 190°C. The chemiluminescence light emission has been associated with consumption of double bonds in polybutadiene, and a corresponding rate constant and activation energies of chemiluminescence decay from both the isothermal and nonisothermal parts of chemiluminescence-time curves have been determined. As demonstrated by these curves, an attempt, to stabilize the blends toward thermooxidation by the peroxide decomposer and stabilizer led to retardation of the oxidation process only and further investigation searching for an optimum stabilizing system is required. © 1993 John Wiley & Sons, Inc.     

Influence of inspiratory resistance on performance during graded exercise tests on a cycle ergometer

Due to more stringent requirements to protect personnel against hazardous gasses, the inspiratory resistance of the present generation of respiratory protective devices tends to increase. Therefore an important question is to what extent inspiratory resistance may increase without giving problems during physical work. In this study the effects of three levels (0.24; 1.4 and 8.3 kPa s l⁻¹) of inspiratory resistance were tested on maximal voluntary performance. Nine male subjects performed a graded exercise test on a cycle ergometer with and without these three levels of inspiratory resistance. Oxygen consumption, heart rate, time to exhaustion and external work were measured. The results of these experiments showed that increasing inspiratory resistance led to a reduction of time to exhaustion (TTE) on a graded exercise test(GXT). Without inspiratory resistance the mean TTE was 11.9 min, the three levels of resistance gave the following mean TTE's: 10.7, 7.8 and 2.7 min. This study showed that TTE on a GXT can be predicted when physical fitness (VO₂-max) of the subject and inspiratory resistance are known. The metabolic rate of the subjects was higher with inspiratory resistance, but no differences were found between the three selected inspiratory loads. Other breathing parameters as minute ventilation, tidal volume, expiration time and breathing frequency showed no or minor differences between the inspiratory resistances. The most important conclusion of these experiments is that the overall workload increases due to an increase in inspiratory resistance by wearing respiratory protective devices.     

A control system for automated multiscale measuring systems

Quality inspection of micro systems on wafer scale must cope with conflicting demands: nanometer accuracy and high velocity in a comparatively large workspace. An Automated Multiscale Measuring System (AMMS) combines multiple sensors that operate at specific scales by an intelligent measurement strategy in order to balance speed and accuracy. The AMMS demonstrator is based on a modified Mahr MFU 100 with a position and tilt deflection measurement resolution of 1 nm. In this paper multiscale models of a horizontal axis with an operating range of 200 mm and their application to state linearization and control parameterization of the residual dynamics according to multiscale sensor system characteristics are developed and discussed. Main modeling issues are sliding and submicron presliding friction for model-based compensation and control, reaching from submicron positioning to high-velocity trajectory tracking with desired performance. A new experimental design for the identification of presliding friction parameters and a higher-order friction calculator are presented. Experimental results show the effectiveness of this approach.     

Visual sensitivity in the black-bellied tree duck (Dendrocygna autumnalis), a crepuscular species.

Produced visual adaptation curves for 3 black-bellied tree ducks using D. S. Blough's (1955) psychophysical tracking procedure. 2 scotopic curves from different preexposure light intensities and 1 photopic curve were generated. Nonlinear regression curves were then fit to the raw data. The mean scotopic thresholds did not differ significantly, but as expected, they were significantly lower than the mean photopic threshold. Time to the curves' asymptotes correlated with preexposure light intensity. Although the adaptation curves showed no distinct rod-cone "break," retinal histology revealed a duplex retina with a preponderance of rods, which reflects this species' crepuscular habits. Results are discussed in relation to the ecology of the species. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using Entropy Analysis to Find Encrypted and Packed Malware

In statically analyzing large sample collections, packed and encrypted malware pose a significant challenge to automating the identification of malware attributes and functionality. Entropy analysis examines the statistical variation in malware executables, enabling analysts to quickly and efficiently identify packed and encrypted samples.