Surface-enhanced Raman spectroscopic analysis of N6-benzylaminopurine residue quantity in sprouts with gold nanoparticles

ABSTRACT

A rapid and quantitative method for the determination of N⁶-Benzylademine (N⁶-BA) was established through the application of surface-enhanced Raman spectroscopy (SERS). The Raman peak intensities of N⁶-BA at 1002 cm^?1 positively correlated to N⁶-BA concentrations in sprout extracts. The R² reached 0.99, and RSDs calculated below 10% at the concentration range of 0.1 ～5μg mL^?1. The average recoveries were 80.0% ～ 98.2% for blank samples intentionally contaminated at differing levels of 0.04, 0.4, and 1 μg g^?1. The whole procedure, including sample preparation and SERS detection, did not exceed 30 min for a set of 6 samples. This study indicates that SERS is a promising technique for rapid tracing analysis and on-site testing of N⁶-BA.     

A High-Volume Sampler for the Determination of Particle Size Distributions in Ambient Air

A size selective particle sampler has been developed for continuous sampling of the urban aerosol over periods ranging from hours to weeks, providing relatively large sample weights. The system, which is now operating in New York City, uses a parallel array of two-stage samplers. The cyclones used as the first stage collectors have 50% particle retention at 3.5,2.5,1.5 and 0.5 µm aerodynamic diameter, respectively. Undersize particles which pass through the cyclones are captured on glass fiber filters. Equal intake velocities are assured by using flow equalizers on the inlets to the cyclones. Accurate control of the flow through the cyclones is obtained by the use of an integrated circuit pressure transducer in conjunction with a specially designed feedback control circuit. The collection efficiencies of the cyclone were calibrated using monodisperse ferric oxide test aerosols tagged with Tc-99m. Mass balances of the par-ticulates collected on the cyclones and filters are obtained for the five sampling stages. Preliminary results show the distributions of the total suspended particulates in New York City to be bimodal. The distributions of lead, copper, and manganese with particle size are also discussed.     

Characterization of Carbonaceous Species of Ambient PM2.5 in Beijing,China

Abstract

One-week integrated fine particulate matter (i.e., particles <2.5 μm in diameter; PM_2.5) samples were collected continuously with a low-flow rate sampler at a downtown site (Chegongzhuang) and a residential site (Tsinghua University) in Beijing between July 1999 and June 2000. The annual average concentrations of organic carbon (OC) and elemental carbon (EC) at the urban site were 23.9 and 8.8 μg m^?3, much higher than those in some cities with serious air pollution. Similar weekly variations of OC and EC concentrations were found for the two sampling sites with higher concentrations in the winter and autumn. The highest weekly variations of OC and EC occurred in the winter, suggesting that combustion sources for space heating were important contributors to carbonaceous particles, along with a significant impact from variable meteorological conditions. High emissions coupled with unfavorable meteorological conditions led to the max weekly carbonaceous concentration the week of November 18–25, 1999. The weekly mass ratios of OC:EC ranged between 2 and 4 for most samples and averaged 2.9, probably suggesting that secondary OC (SOC) is present most weeks. The range of contemporary carbon fraction, based on the C14 analyses of eight samples collected in 2001, is 0.330–0.479. Estimated SOC accounted for ～38% of the total OC at the two sites. Average OC and EC concentrations at Tsinghua University were 25% and 18%, respectively, higher than those at Chegongzhuang, which could be attributed to different local emissions of primary carbonaceous particles and gaseous precursors of SOC, as well as different summer photochemical intensities between the two locations.     

DNA damage in Populus tremuloides clones exposed to elevated O3

The effects of elevated concentrations of atmospheric tropospheric ozone (O₃) on DNA damage in five trembling aspen (Populus tremuloides Michx.) clones growing in a free-air enrichment experiment in the presence and absence of elevated concentrations of carbon dioxide (CO₂) were examined. Growing season mean hourly O₃ concentrations were 36.3 and 47.3 ppb for ambient and elevated O₃ plots, respectively. The 4th highest daily maximum 8-h ambient and elevated O₃ concentrations were 79 and 89 ppb, respectively. Elevated CO₂ averaged 524 ppm (+150 ppm) over the growing season. Exposure to O₃ and CO₂ in combination with O₃ increased DNA damage levels above background as measured by the comet assay. Ozone-tolerant clones 271 and 8L showed the highest levels of DNA damage under elevated O₃ compared with ambient air; whereas less tolerant clone 216 and sensitive clones 42E and 259 had comparably lower levels of DNA damage with no significant differences between elevated O₃ and ambient air. Clone 8L was demonstrated to have the highest level of excision DNA repair. In addition, clone 271 had the highest level of oxidative damage as measured by lipid peroxidation. The results suggest that variation in cellular responses to DNA damage between aspen clones may contribute to O₃ tolerance or sensitivity.     

Bottom-Up Risk Regulation? How Nanotechnology Risk Knowledge Gaps Challenge Federal and State Environmental Agencies

Nanotechnologies have been called the "Next Industrial Revolution." At the same time, scientists are raising concerns about the potential health and environmental risks related to the nano-sized materials used in nanotechnologies. Analyses suggest that current U.S. federal regulatory structures are not likely to adequately address these risks in a proactive manner. Given these trends, the premise of this paper is that state and local-level agencies will likely deal with many "end-of-pipe" issues as nanomaterials enter environmental media without prior toxicity testing, federal standards, or emissions controls. In this paper we (1) briefly describe potential environmental risks and benefits related to emerging nanotechnologies; (2) outline the capacities of the Toxic Substances Control Act, the Clean Air Act, the Clean Water Act, and the Resources Conservation and Recovery Act to address potential nanotechnology risks, and how risk data gaps challenge these regulations; (3) outline some of the key data gaps that challenge state-level regulatory capacities to address nanotechnologies' potential risks, using Wisconsin as a case study; and (4) discuss advantages and disadvantages of state versus federal approaches to nanotechnology risk regulation. In summary, we suggest some ways government agencies can be better prepared to address nanotechnology risk knowledge gaps and risk management.     

高铁对长三角区域旅游一体化影响计量研究

高铁正成为影响我国区域旅游一体化的关键性因素,已有高铁旅游影响研究普遍存在供需分离的系统化视角缺位问题。立足多目的地-多客源地交互的旅游供需空间系统视角,利用GIS集成方法和旅游系统引力模型研究了有无高铁网络两种情境下的长三角区域旅游竞争力和出游力格局,分析了高铁对区域旅游一体化影响的具体方向、程度和意义。结果发现:(1)高铁对长三角区域旅游一体化影响增强,扩大了旅游竞争力、出游力等级差异,带来逆向均衡一体化效应;(2)高铁强化了长三角区域旅游格局的核心-边缘结构,边缘地区非高铁城市的旅游竞争力和出游力进一步被削弱,而核心高铁城市上海的中心性仍在增强;(3)高铁开通后,边缘地区新增开高铁城市的旅游格局变化最大,但固有劣势使其不能从根本上改变区域旅游整体的非均衡发展态势;(4)高铁时空压缩在削弱空间距离因素影响的同时,促进了区域旅游竞合关系的本位回归,规避旅游供给的同质化竞争、强调差异化发展是发挥高铁旅游一体化联动效应的根本路径模式。最后,指出高铁开通可以为边缘地区城市提供相对公平的交通发展平台,是防止边缘地区城市进一步被边缘化的必要条件,进而提出了促进区域旅游一体化发展的具体政策建议。     

Isolation of single circulating trophoblasts from maternal circulation for noninvasive fetal copy number variant profiling

Objective

To develop a multi-step workflow for the isolation of circulating extravillous trophoblasts (cEVTs) by describing the key steps enabling a semi-automated process, including a proprietary algorithm for fetal cell origin genetic confirmation and copy number variant (CNV) detection.

Methods

Determination of the limit of detection (LoD) for submicroscopic CNV was performed by serial experiments with genomic DNA and single cells from Coriell cell line biobank with known imbalances of different sizes. A pregnancy population of 372 women was prospectively enrolled and blindly analyzed to evaluate the current workflow.

Results

An LoD of 800 Kb was demonstrated with Coriell cell lines. This level of resolution was confirmed in the clinical cohort with the identification of a pathogenic CNV of 800 Kb, also detected by chromosomal microarray. The mean number of recovered cEVTs was 3.5 cells per sample with a significant reverse linear trend between gestational age and cEVT recovery rate and number of recovered cEVTs. In twin pregnanices, evaluation of zygosity, fetal sex and copy number profiling was performed in each individual cell.

Conclusion

Our semi-automated methodology for the isolation and single-cell analysis of cEVTS supports the feasibility of a cell-based noninvasive prenatal test for fetal genomic profiling.     

Evaluation of bio-aerosols type,density, and modeling of dispersion in inside and outside of different wards of educational hospital

Environmental Science and Pollution Research - Exposure to bioaerosols in the air of hospitals is associated with a wide range of adverse health effects due to the presence of airborne...     

清河流域水生态维持功能评估

利用野外样点调查数据、遥感解译数据和多年降水监测数据,从生物多样性维持功能、生境维持功能和水资源支持功能3个方面对2011年清河流域水生态维持功能进行评估,为"十二五"期间水专项在清河流域开展水环境管理技术实施示范效果评估奠定基础。结果表明:2011年清河流域生物多样性维持功能和生境维持功能较好,而水资源支持功能较差。建议通过开展生态保护工程增加植被覆盖度,增强水资源支持功能和水土保持能力。