A novel extraction technique combining dispersive liquid-liquid microextraction (DLLME) with magnetic solid-phase extraction (MSPE) is presented for pre-concentration of four primary aromatic amines (PAAs) released from azo dyes in paper samples prior to high performance liquid chromatography (HPLC). n-Octanol was used as the extractant and hydrophobic oleic acid modified Fe3O4 nanoparticles (Fe3O4@OA NPs) as an efficient adsorbent was applied to retrieve the PAAs-containing n-octanol in the DLLME step. Because of the rapid mass transfer associated with the DLLME and MSPE steps, fast extraction could be achieved. The main parameters affecting the efficiency of MSPE-DLLME procedure of PAAs were investigated and optimized. Under optimum conditions, the recoveries ranged from 79.6 to 88.5% and the limits of detection (LODs) were in the range of 0.21-1.16 ng mL-1 (S / N = 3). The intra-day precision (relative standard deviation (RSD)) was below 7.8% and inter-day RSD was less than 11%.

A new method using nonanoic acid-coated magnetic Fe3O4 nanoparticles as adsorbent has been developed for the single-step extraction and preconcentration of lead and copper in tobacco samples. Transmission electron microscopy and X-ray diffraction spectrometry were used to characterize the adsorbent. The experimental parameters affecting extraction efficiency, including amount of nanoparticles, volume of chelating reagents, sample pH, ultrasonic time and desorption conditions were investigated. The analytes desorbed from nanoparticles were determined by flame atomic absorption spectrometry. Under the optimum conditions, good linearity was obtained in the range of 2-400 µg L-1 for copper and 5-800 µg L-1 for lead (r > 0.998, p < 0.05). The limits of detection for copper and lead were 0.2 and 0.5 µg L-1, with enrichment factors of 45 and 52, respectively. The method was successfully employed to tobacco sample analysis and got excellent recoveries between 89.2 and 100.7% with relative standard deviations (n = 6) of 4.5-5.9%.

ABSTRACT A simple and sensitive method for simultaneous determination of furan and vinyl acetate (VA) in vapor phase of mainstream cigarette smoke with cold trap and gas chromatography-mass spectrometry (GC-MS) was developed. A Cambridge filter pad (CFP) was placed in front of the impingers of smoking machine to remove the particle phase from cigarette smoke. Furan and VA in vapor phase of mainstream cigarette smoke were collected in two impingers connected in series by filled with methanol at -78°C. The solutions were added with deuterium-labeled furan-d4 and VA-d6 as internal standards and analyzed by GC-MS. The results showed that the calibration curves for furan and VA were linear (r2 > 0.9995) over the studied concentration range. The intra- and inter-day precision values for furan and VA were <7.07% and <9.62%, respectively. The extraction recoveries of furan and VA were in the range of 94.5-97.7% and 92.3-94.9%, respectively. Moreover, the limits of detection for furan and VA were 0.028 µg mL-1 and 1.3 ng mL-1, respectively. The validated method has been successfully applied to determine the emissions of furan and VA in the vapor phase of mainstream cigarette smoke under International Organization for Standardization (ISO) and Canadian Intense (CI) smoking regimen.

Abstract The sexually dimorphic expression of H19/IGF2 is evolutionarily conserved. To investigate whether the expression of H19/IGF2 in the female porcine eye is sex-dependent, gene expression and methylation status were evaluated using quantitative real-time PCR (qPCR) and bisulfite sequencing PCR (BSP). We hypothesized that H19/IGF2 might exhibit a different DNA methylation status in the female eye. In order to evaluate our hypothesis, parthenogenetic (PA) cells were used for analysis by qPCR and BSP. Our results showed that H19 and IGF2 were over-expressed in the female eye compared with the male eye (3-fold and 2-fold, respectively). We observed a normal monoallelic methylation pattern for H19 differentially methylated regions (DMRs). Compared with H19 DMRs, IGF2 DMRs showed a different methylation pattern in the eye. Taken together, these results suggest that elevated expression of H19/IGF2 is caused by a specific chromatin structure that is regulated by the DNA methylation status of IGF2 DMRs in the female eye.

The stability of artificial, sand-binding communities has not yet fully studied. A similarity index was developed to evaluate the stability of artificial communities in shifting and semi-fixed sand dunes. This similarity index consisted of 8 indicators (i.e., vegetation cover, Shannon-Wiener Index, biomass, organic matter, Total N, available P and K, and sand particle ratio). The relative weight of these indicators was obtained using an analytic hierarchy process (AHP) method. Stability was compared on Artemisia halodendron Turczaninow ex Besser, Bull communities in shifting and semifixed sand dunes, and of Caragana microphylla Lam. communities with different planting ages. The similarity indexes of the A. halodendron communities were 0.24 and 0.54 in shifting and semi-fixed sand dunes, respectively. The peak stability of C. microphylla communities was 0.55, and it was reached when these communities were 20-year-old. It is suggested that A. halodendron communities should be planted preferentially in semi-fixed to moving sand dunes. Furthermore, the planting age of artificial communities should be included in planting programs. This study improved the understanding of some mechanisms contributing to maintain community stability, and is critical for guiding the artificial planting in sand dunes.

La estabilidad de comunidades artificiales que contribuyen a la fijación de suelos arenosos no se ha estudiado completamente. Se desarrolló un índice de similitud para evaluar la estabilidad de comunidades artificiales en dunas móviles y fijadas medianamente. Este índice de similitud consistió de 8 indicadores (cobertura vegetal, índice de Shannon-Wiener, biomasa, materia orgánica, N total, P y K disponibles, y relación de partículas de arena). La importancia relativa de estos indicadores se obtuvo utilizando un método de procesamiento jerárquico analítico (AHP). Se comparó la estabilidad de comunidades de Artemisia halodendron Turczaninow ex Besser, Bull en dunas móviles y fijadas medianamente, y la de comunidades de Caragana microphylla Lam. de diferentes edades de plantación. Los índices de similitud de las comunidades de A. halodendron fueron 0,24 y 0,54 en dunas móviles y fijadas medianamente, respec- tivamente. La estabilidad máxima de las comunidades de C. microphylla fue 0,55, la que se obtuvo cuando dichas comunidades alcanzaron 20 años de edad. Se sugiere que las comunidades de A. halodendron se deberían plantar preferencialmente en dunas fijadas medianamente a móviles. Además, la edad de plantación de las comunidades artificiales se debería incluir en programas de plantación. Este estudio mejoró el entendimiento de algunos mecanismos que contribuyen a mantener la estabilidad de las comunidades, y es crítico para guiar la plantación artificial en áreas de dunas.

Ultrasound-assisted extraction (UAE) of polysaccharide from Maryland tobacco leaves was studied by response surface methodology. Furthermore, the crude polysaccharide was purified and two components (Fr-I and Fr-II) were obtained. FT-IR spectral analysis of the purified polysaccharide revealed prominent characteristic groups. The monosaccharide composition analysis by gas chromatography-mass spectrometry (GC/MS) indicated the main composition between Fr-I and Fr-II was different. Furthermore, thermo gravimetric analysis (TGA) indicated the degradation temperature (Td) of the Fr-I (241 ºC) was higher than those of Fr-II (216 ºC). Detected by the pyrolysis gas chromatography-mass spectrometry (py-GC/MS), it was found that the main kinds of pyrolysis products from both Fr-I and Fr-II were similar. Finally, On the basis of hydroxyl and DPPH radical scavenging assay, Fr-II has stronger antioxidant activities than Fr-I. The thermal behavior and antioxidant activity might be attributed to the configuration of the chemical compositions.