Photoluminescence-Based Techniques for the Detection of Micro- and Nanoplastics

The growing numbers related to plastic pollution are impressive, with ca. 70 % of produced plastic (>350 tonnes/year) being indiscriminately wasted in the environment. The most dangerous forms of plastic pollution for biota and human health are micro- and nano-plastics (MNPs), which are ubiquitous and more bioavailable. Their elimination is extremely difficult, but the first challenge is their detection since existing protocols are unsatisfactory for microplastics and mostly absent for nanoplastics. After a discussion of the state of the art for MNPs detection, we specifically revise the techniques based on photoluminescence that represent very promising solutions for this problem. In this context, Nile Red staining is the most used strategy and we show here its pros and limitations, but we also discuss other more recent approaches, such as the use of fluorogenic probes based on perylene-bisimide and on fluorogenic hyaluronan nanogels, with the added values of biocompatibility and water solubility.     

一种高稳定性光纤F-P标准具的设计

法布里-珀罗(F-P)标准具广泛应用于光纤通信与光纤传感领域。实心标准具受自身材料的限制,无法满足高稳定性的要求。空气隙标准具采用热膨胀系数极低的垫片,提高了器件的温度稳定性能。介绍了低温漂光纤F-P标准具的设计和制作,出射光自由光谱范围为100GHz,损耗为3dB,0~70℃温度漂移小于3GHz。相比于采用传统方法制作的标准具,该光纤F-P标准具稳定性更高,解决了实心标准具折射率和热膨胀变化大的问题。     

Topological “interfacial” polymer chemistry: Dependency of polymer “shape” on surface morphology and stability of layer structures when heating organized molecular films of cyclic and linear block copolymers of n‐butyl acrylate‐ethylene oxide

The “topological polymer chemistry” of amphiphilic linear and cyclic block copolymers at an air/water interface was investigated. A cyclic copolymer and two linear copolymers (AB‐type diblock and ABA‐type triblock copolymers) synthesized from the same monomers were used in this study. Relatively stable monolayers of these three copolymers were observed to form at an air/water interface. Similar condensed‐phase temperature‐dependent behaviors were observed in surface pressure–area isotherms for these three monolayers. Molecular orientations at the air/water interface for the two linear block copolymers were similar to that of the cyclic block copolymer. Atomic force microscopic observations of transferred films for the three polymer types revealed the formation of monolayers with very similar morphologies at the mesoscopic scale at room temperature and constant compression speed. ABA‐type triblock linear copolymers adopted a fiber‐like surface morphology via two‐dimensional crystallization at low compression speeds. In contrast, the cyclic block copolymer formed a shapeless domain. Temperature‐controlled out‐of‐plane X‐ray diffraction (XRD) analysis of Langmuir–Blodgett (LB) films fabricated from both amphiphilic linear and cyclic block copolymers was performed to estimate the layer regularity at higher temperatures. Excellent heat‐resistant properties of organized molecular films created from the cyclic copolymer were confirmed. Both copolymer types showed clear diffraction peaks at room temperature, indicating the formation of highly ordered layer structures. However, the layer structures of the linear copolymers gradually disordered when heated. Conversely, the regularity of cyclic copolymer LB multilayers did not change with heating up to 50 °C. Higher‐order reflections (d₀₀₂, d₀₀₃) in the XRD patterns were also unchanged, indicative of a highly ordered structure. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 486–498     

Radiocaesium pollution of fly agaric Amanita muscaria in fruiting bodies decreases with developmental stage

Amanita muscaria collected from a forested area in northern Poland in 2015 were analysed for activity concentrations of ¹³⁷Cs and ⁴⁰K. Total K concentration values were calculated from ⁴⁰K data. Mushrooms were grouped in six fruiting bodies size classes regarding to their developmental stage. The ¹³⁷Cs activity concentrations declined in A. muscaria as the fruiting bodies maturated. The contents of ⁴⁰K/K activity remained constant in caps at different developmental stage, while for stipes an increase was around twofold (⁴⁰K from 925?±?55 Bq kg^?1 dry biomass in the baby individuals and 1600?±?63–1700?±?53 Bq kg^?1 dry biomass in two oldest classes). A. muscaria is a weak accumulator of ¹³⁷Cs, while a steep drop in activity concentrations of this nuclide in the fruiting bodies as they maturate has not been reported earlier for mushrooms. Clearly, a fate of ¹³⁷Cs in A. muscaria is highly different from that of ⁴⁰K/K that is an essential element to fungi. In parallel, an observed increase in the content of ⁴⁰K/K in stipes of fruiting bodies with developmental state can be related to its ‘hardening’ and more fibrous nature with age and basic function to support the cap, but this has not been studied.     

Selection of sampling adsorbents and optimisation and validation of a GC-MS/MS method for airborne pesticides

A methodology for the sampling and determination of airborne pesticides has been developed. The trapping efficiency of three adsorbents, namely XAD-2,XAD-4 and a sandwich sorbent (PUF-XAD2-PUF), was tested for 34 pesticides and the latter was selected because it presented the highest retention capacity without breakthrough. Pesticides were determined by gas chromatography coupled to an ion trap mass spectrometer in tandem. The method showed recoveries ranging from 70% to 120% with limits of quantification in the range of 16.1–322.6 pg m^?3 when 155 m³ were sampled. This analytical strategy was applied to 10 indoor air samples collected in dwellings from the Valencian Region. Six pesticides, namely diphenylamine, pyrimethanil, bifenthrin, lambda-cyhalothrin, permethrin and cypermethrin were detected in indoor samples with concentrations ranging from 1.46 to 22.02 ng m^?3.     

SPH方法研究空气在平板入水中的影响

飞机水上迫降以及船体在高速行驶时,均会发生结构物砰击水面的现象,当结构物底面较为平坦,砰击水面时会捕获空气,在板底形成空气垫。研究空气垫的形成及影响,有助于对结构物进行更准确的载荷分析。该问题的研究涉及到气固液三相的相互作用,在数值模拟中仍是一个挑战,本文使用光滑粒子流体动力学(SPH)方法对该问题进行模拟。首先,与实验结果进行对比;其次,系统地研究了平板形成空气垫以及砰击水面的过程,考查了空气、水和平板的动能变化。对比了在SPH模拟中考虑空气与不考虑空气得到的水压力场和平板所受压力,说明了空气对结果的影响;最后,研究了平板宽度对空气垫形成的影响,从而进一步影响加速度。     

Analysis of volatile organic compounds in indoor environments using thermal desorption with comprehensive two‐dimensional gas chromatography and high‐resolution time‐of‐flight mass spectrometry

Building‐related health effects are frequently observed. Several factors have been listed as possible causes including temperature, humidity, light conditions, presence of particulate matter, and microorganisms or volatile organic compounds. To be able to link exposure to specific volatile organic compounds to building‐related health effects, powerful and comprehensive analytical methods are required. For this purpose, we developed an active air sampling method that utilizes dual‐bed tubes loaded with TENAX‐TA and Carboxen‐1000 adsorbents to sample two parallel air samples of 4 L each. For the comprehensive volatile organic compounds analysis, an automated thermal desorption comprehensive two‐dimensional gas chromatography high‐resolution time‐of‐flight mass spectrometry method was developed and used. It allowed targeted analysis of approximately 90 known volatile organic compounds with relative standard deviations below 25% for the vast majority of target volatile organic compounds. It also allowed semiquantification (no matching standards) of numerous nontarget air contaminants using the same data set. The nontarget analysis workflow included peak finding, background elimination, feature alignment, detection frequency filtering, and tentative identification. Application of the workflow to air samples from 68 indoor environments at a large hospital complex resulted in a comprehensive volatile organic compound characterization, including 178 single compounds and 13 hydrocarbon groups.     

利用反射太赫兹时域强度分布定量检测沙粒中的微量原油

原油污染是海洋生物和环境安全的主要威胁之一,检测近海沙粒中的微量原油对于环境保护和原油勘探有着重要意义.本文采用反射式太赫兹时域波形对近海沙粒中的原油进行定量检测,详细地分析了延迟时间与沙粒中的原油浓度的关系.结果表明,原油浓度与延迟时间呈线性递减关系,反射式太赫兹时域波形是一种具有潜力的污染定量检测方法.     

Analysis and Fate of Dibenzothiophene Derivatives in the Marine Environment

Abstract

Dibenzothiophene (DBT) and related methylated derivatives are known to be among the most persistent and probably the most toxic PAH in the marine environment. Their analysis and their fate by photo-oxidation and biodegradation were studied.

The methylated DBT isomers, provided that they are resolved by high resolution GC, were used as organic markers of oil pollution in oysters. The determination of the relative distribution of the four monomethyl DBT allowed to characterize the source of pollution in an oyster-area in the North Brittany (France).

The fate of methylated DBT compounds was studied in a controlled sea-water enclosure where Arabian light oil was spilled. Analysis of the weathered oil showed that: (i) oil was degraded by photo-oxidation at a rate of 0.004% day; (ii) the half-lives of photolysis of methylated DBT was dependent upon the number of methyl groups on the aromatic nucleus: 8 days for DBT, 20 days for methyl-1 DBT and more than 2 years for trimethylated DBT. Compounds solubilized in the water column were identified as methyl-substituted dibenzothiophene sulfoxides and sulfones by HPLC with synchrofluorescence and GC-flame photometric detection.

The metabolic pathway of DBT was established in vitro. Rat microsomes transformed this substrate to DBT-5-oxide and subsequently to DBT-5-dioxide. Such an enzymatic S-oxidation was shown to be principally Cytochrome-P-450 dependent. It is suggested that the mixed-function oxidase (MFO) activity of marine species could be evaluated by this S-oxidation test in addition to the usual aryl hydrocarbon hydroxylase.