The mechanism of health effects caused by organohalogen pollutants, e.g., toxins from electronic waste (e-waste), is poorly understood. We supposed that microRNAs (miRNAs), an important post-transcriptional regulator, could play a role in this process. In this study, fasting peripheral blood samples were collected from residents living at an e-waste site in northern China and a nearby reference population. Concentrations of e-waste related organohalogen pollutants in plasma from the exposure group were higher than the corresponding measurement in the reference group. Correspondingly, sixty miRNAs in plasma showed > 2-fold change between the two groups in microarray analysis. Among them, miR-125a-5p was confirmed to be upregulated by qRT-PCR and its validated targets were enriched in responses to xenobiotics and cancer related pathways. Furthermore, significant positive conelations were found between levels of miR-125a-5p in plasma and reactive oxygen species (ROS) in polymorphonuclear neutrophil leukocytes (P < 0.05). These evidences suggested oxidative stress might be an intermediate between e-waste related POPs exposure and alteration of plasma miRNA.
This study aims to simulate depositions of size-segregated particles in human airway in Beijing, China during seasons when fine particulate matter concentrations are high (December 2011 and April 2012). Particle size distributions (5.6-560 nm, electrical mobility diameter) near a major road in Beijing were measured by the TSI Fast Mobility Particle Sizer (FMPS). The information of size distributions provided by FMPS was applied in the Multiple-Path Particle Dosimetry model (MPPD) to quantify number and mass depositions of particles in human airway including extrathoracic (ET), tracheobronchial (TB), and pulmonary (PUL) regions of exposed Chinese in Beijing. Our results show that under ambient conditions, particle number concentration (NC) deposition in PUL is the highest in the three major regions of human airway. The total particle NC deposition in human airway in winter is higher than that in spring, especially for ultrafine particles (1.8 times higher) while particle mass concentration (MC) deposition is higher in spring. Although particle MC in clean days are much lower than that in heavily polluted days, total particle NC deposition in human airway in clean days is comparable to that in heavily polluted days. NC deposition for nucleation mode particles (10-20 nm, aerodynamic diameter) in clean days is higher than that in heavily polluted days. MC deposition for accumulation mode particles (100-641 nm, aerodynamic diameter) in heavily polluted days is much higher than that in clean days, while that of nucleation mode is negligible. The temporal variation shows that the arithmetic mean and the median values of particle NC and MC depositions in the evening are both the highest, followed by morning and noon, and it is most likely due to increased contribution from traffic emissions. (C) 2015 Elsevier Ltd. All rights reserved.
The structural and electronic properties of monolayer graphene synthesized on a periodically reconstructed substrate can be widely modulated by the generation of superstructure patterns, thereby producing interesting physical properties, such as magnetism and superconductivity. Herein, using a facile chemical vapor deposition method, we successfully synthesized high-quality monolayer graphene with a uniform thickness on Au foils. The hex-reconstruction of Au(001), which is characterized by striped patterns with a periodicity of 1.44 nm, promoted the formation of a quasi-one-dimensional (1D) graphene superlattice, which served as a periodic quasi-1D modulator for the graphene overlayer, as evidenced by scanning tunneling microscopy/spectroscopy. Intriguingly, two new Dirac points were generated for the quasi-1D graphene superlattice located at −1.73 ± 0.02 and 1.12 ± 0.12 eV. Briefly, this work demonstrates that the periodic modulation effect of reconstructed metal substrates can dramatically alter the ele...
Biogenic secondary organic aerosols (SOA) are generally considered to be more abundant in summer than in winter. Here, polar organic marker compounds in urban background aerosols from Mumbai were measured using gas chromatography-mass spectrometry. Surprisingly, we found that concentrations of biogenic SOA tracers at Mumbai were several times lower in summer (8-14 June 2006; wet season; n = 14) than in winter (13-18 February 2007; dry season; n = 10). Although samples from less than 10% of the season are extrapolated to the full season, such seasonality may be explained, by the predominance of the southwest summer monsoon, which brings clean marine air masses to Mumbai. While heavy rains are an important contributor to aerosol removal during the monsoon season, meteorological data (relative humidity and T) suggest no heavy rains occurred during our sampling period. However, in winter, high levels of SOA and their day/night differences suggest significant contributions of continental aerosols through long-range transport together with local sources. The winter/summer pattern of SOA loadings was further supported by results from chemical transport models (NAQPMS and GEOS-Chem). Furthermore, our study suggests that monoterpene- and sesquiterpene-derived secondary organic carbon. (SOC) were more significant than those of isoprene- and toluene-SOC at Mumbai.
Organic-inorganic hybrid perovskite solar cells have been developing rapidly in the past several years, and their power conversion efficiency has reached over 20%, nearing that of polycrystalline silicon solar cells. Because the diffusion length of the hole in perovskites is longer than that of the electron, the performance of the device can be improved by using an electron transporting layer, e.g., TiO2, ZnO and TiO2/Al2O3. Nano-structured electron transporting materials facilitate not only electron collection but also morphology control of the perovskites. The properties, morphology and preparation methods of perovskites are reviewed in the present article. A comprehensive understanding of the relationship between the structure and property will benefit the precise control of the electron transporting process and thus further improve the performance of perovskite solar cells.
Organic-inorganic hybrid perovskite solar cells have been developing rapidly in the past several years, and their power conversion efficiency has reached over 20%, nearing that of polycrystalline silicon solar cells. Because the diffusion length of the hole in perovskites is longer than that of the electron, the performance of the device can be improved by using an electron transporting layer, e.g., TiO2, ZnO and TiO2/Al2O3. Nano-structured electron transporting materials facilitate not only electron collection but also morphology control of the perovskites. The properties, morphology and preparation methods of perovskites are reviewed in the present article. A comprehensive understanding of the relationship between the structure and property will benefit the precise control of the electron transporting process and thus further improve the performance of perovskite solar cells.
In this Letter, we investigate the feasibility of focusing relativistic laser pulses toward diffraction limit by near-critical density plasma lenses. A theoretical model is developed to estimate the focal length of the plasma lens. Particle-in-cell simulations with various pulse parameters, such as pulse duration, beam waist, and intensity, are performed to show the robustness of plasma lenses. The results prove that the near-critical density plasma lenses can be deployed to obtain higher laser peak intensities with sub-wavelength focal spots in experiments.
The aim of this review article is to introduce recent studies on an emergent class of singlet oxygen photosensitizers of potential applications to the photodynamic therapy, with a primary focus on the cyclometalated transition-metal complexes. Singlet oxygen photosensitization performances of various cyclometalated Ir and Pt scaffolds are reviewed, and the general photo-physical properties of relevant systems and the mechanisms of singlet oxygen production via photo-sensitization are also briefly discussed. Thus far, investigations of singlet oxygen sensitization by such Ir and Pt complexes are mainly carried out in organic solvents and under non-physiological conditions, while some research efforts have been made at examining the feasibility of applying pertinent cyclometalated complexes to photodynamic therapy.
A new micromechanics method is proposed to investigate the effective properties of saturated porous media with connected pores. This topic is seldom discussed in the literature because it is difficult to describe the connected pores and skeleton using conventional micromechanics methods. A new micromechanics model (i.e., Model I) is suggested to characterize such saturated porous media in which the pores saturated by fluid are taken as the matrix, and the interconnected randomly oriented long fiber (ROLF)-like solid skeleton is taken as the inclusions. The proposed model is verified by numerical simulations; the simulation results indicate that the difference of the elastic constants calculated for media with interconnected pores and for those with dispersed ROLF solid inclusions is small. Thus, the elastic moduli of Model I can be treated as approximate values for porous media with connected pores. Further, a modified Eshelby tensor for spherical inclusions is derived based on the equivalency of the elastic moduli of Model I and a conventional micromechanics model in which spherical fluid inclusions are distributed randomly in a solid matrix. By means of the modified Eshelby tenor, conventional micromechanics methods can be utilized directly to calculate the effective mechanical and thermal properties of saturated porous media with interconnected pores. Some examples are presented to show that the macroscopic elastic moduli predicted by the proposed method are in good agreement with test data found in the literature.
A new micromechanics method is proposed to investigate the effective properties of saturated porous media with connected pores. This topic is seldom discussed in the literature because it is difficult to describe the connected pores and skeleton using conventional micromechanics methods. A new micromechanics model (i.e., Model I) is suggested to characterize such saturated porous media in which the pores saturated by fluid are taken as the matrix, and the interconnected randomly oriented long fiber (ROLF)-like solid skeleton is taken as the inclusions. The proposed model is verified by numerical simulations; the simulation results indicate that the difference of the elastic constants calculated for media with interconnected pores and for those with dispersed ROLF solid inclusions is small. Thus, the elastic moduli of Model I can be treated as approximate values for porous media with connected pores. Further, a modified Eshelby tensor for spherical inclusions is derived based on the equivalency of the elastic moduli of Model I and a conventional micromechanics model in which spherical fluid inclusions are distributed randomly in a solid matrix. By means of the modified Eshelby tenor, conventional micromechanics methods can be utilized directly to calculate the effective mechanical and thermal properties of saturated porous media with interconnected pores. Some examples are presented to show that the macroscopic elastic moduli predicted by the proposed method are in good agreement with test data found in the literature.