High yield room temperature synthesis of pyranochromenes in neutral cetyltrimethylammonium bromide micellar media

Pyrano[3,2-c]chromene derivatives are heterocycles with a wide range of biological properties. There is actually a need for safer synthesis of heterocycles, using for instance water as a solvent. High selectivity can also be achieved by addition of surface-active reagents to form micelles. Indeed, it is presumed that water facilitates organic reactions by the hydrophobic effect, enhanced hydrogen bonding in the transition state and cohesive energy density. Here, a simple aqueous-mediated protocol is developed for the quantitative synthesis of medicinally relevant pyrano[3,2-c]chromene derivatives by the tandem reaction of readily available reagents in cetyltrimethylammonium bromide micellar media. This new method is a modification of the three-component reaction involving Knoevenagel condensation, Michael addition and cyclization reaction. Yields of 3, 4-dihydropyrano[c]chromenes ranged from 85 to 99 % at room temperature.     

Phototransformation of fibrate drugs in aqueous media

The photochemical conversion of bezafibrate, gemfibrozil, fenofibrate and fenofibric acid has been examined in aqueous media. Irradiation with a solar simulator in distilled water caused about 10% degradation for the first three drugs after 200 hr, while fenofibric acid was completely degraded after 100 hr. Experiments have also been performed in the presence of nitrates or humic acids, considered as environmental photosensitizers, and only for gemfibrozil a reduction of degradation has been observed. Photoproducts have been characterized and the mechanistic pathways discussed on the basis of experimental and literature data.     

Gravity currents in two-layer stratified media

An analytical, experimental and numerical study of boundary gravity currents propagating through a two-layer stratified ambient of finite vertical extent is presented. Gravity currents are supposed to originate from a lock-release apparatus; the (heavy) gravity current fluid is assumed to span the entire channel depth, H, at the initial instant. Our theoretical discussion considers slumping, supercritical gravity currents, i.e. those that generate an interfacial disturbance whose speed of propagation matches the front speed, and follows from the classical analysis of Benjamin (J Fluid Mech 31:209?C248, 1968). In contrast to previous investigations, we argue that the interfacial disturbance must be parameterized so that its amplitude can be straightforwardly determined from the ambient layer depths. Our parameterization is based on sensible physical arguments; its accuracy is confirmed by comparison against experimental and numerical data. More generally, measured front speeds show positive agreement with analogue model predictions, which remain strictly single-valued. From experimental and numerical observations of supercritical gravity currents, it is noted that this front speed is essentially independent of the interfacial thickness, ??, even in the limiting case where ?? = H so that the environment is comprised of a uniformly stratified ambient with no readily discernible upper or lower ambient layer. Conversely, when the gravity current is subcritical, there is a mild increase of front speed with ??. Our experiments also consider the horizontal distance, X, at which the front begins to decelerate. The variation of X with the interface thickness and the depths and densities of the ambient layers is discussed. For subcritical gravity currents, X may be as small as three lock lengths whereas with supercritical gravity currents, the gravity current may travel long distances at constant speed, particularly as the lower layer depth diminishes.     

Real-time monitoring of nanoparticle retention in porous media

Nanoparticles are not specifically targeted in conventional treatment schemes; consequently, typical wastewater treatment systems are ineffective for nanoparticles removal. With rapidly increasing concern over their health effects, improved understanding of nanoparticle transport and retention in porous media filters is critical because of its application in new wastewater treatment methods and for assessment of the fate of the discharged nanoparticles in soil. In this study, a unique and robust integrated method is developed and validated. Experimentally, this approach uses an on-line, real-time, and in situ method for measuring nanoparticle retention dynamics, eliminating the laborious and less accurate sampling and off-line analysis. The data analysis part is a process simulator which provides both kinetic properties of the retention process as well as the overall capacity and loading. This technique is validated by application to the transport and retention of TiO₂ nanoparticles in two vastly different porous filtration media—activated carbon and sand. TiO₂ retained concentrations ranged from 0.24 to 0.37 mg g^?1 for activated carbon and 0.01–0.014 mg g^?1 for sand. The integrated method presented here is useful for both comparison of the filtration effectiveness of various porous materials as well as for process optimization and scale-up for industrial applications.     

Ichthyotoxicity found in cultured media of Protogonyaulax spp.

Ichthyotoxicity was observed in the cultured media from Protogonyaulax catenella and P. tamarensis. No paralytic shellfish poison was detected in the cultured media. Test fish in the cultured media died showing signs of hypoxia. Histological observations of the gills of intoxicated fish indicated that the epithelial cells were swollen and exfoliated from the pillar cell. The cultured media had hemolytic activity against erythrocytes of various animals. The media also decreased the elasticity of eggs of rainbow trout Salmo gairdneri. From these results, it is concluded that the cultured media of both species of Protogonyaulax contain a cytotoxin which is lethal to fish.     

A new photoproduct of the drug furosemide in aqueous media

The solar phototransformation of furosemide has been investigated in aqueous media. Irradiation of the drug in distilled water, in water and humic acids or nitrate ions, and in sewage sludge water affords a new dehalogenated dimer. The formation of the dimer has been explained by the formation of a cation radical intermediate. The low-measured environmental concentration of furosemide with respect to predicted environmental concentration in the Po and Lambro Rivers could be justified by its phototransformation.     

X射线微断层扫描技术(XDMT)在多孔介质中含砷聚集物的三维成像应用

利用X射线微断层差异扫描技术,扫描富砷河床沉积物及人工含砷样品,对多孔介质中的含砷聚集物进行成像分析.利用Avizo 6和Blob3D等工具对获取的数据进行处理,从而实现了含砷聚集物的三维可视化成像.结果显示,大量的含砷聚集物沉积在多孔介质颗粒表面,且不同尺寸的聚集物呈现出明显的形态多样化特征.小颗粒聚集物趋向于球形,大颗粒聚集物则趋向于扁平状.研究表明,该技术可在不破坏样品的前提下,直接观测多孔介质因沉积作用导致其内部结构的变化.     

黄孢原毛平革菌对固体介质中染料的降解反应

用黄孢原毛平革菌(Phanerochaetechrysosporium)3品系在固体介质中建立染料的降解反应体系,分光光度法测定染料的脱色降解率。黄孢原毛平革菌在琼脂、沙子及土壤等固体介质中均能有效地降解偶氮染料、蒽醌染料及聚合染料;植物材料玉米芯和木屑可作为共代谢碳源被该菌利用;BKM F 1767菌种降解能力最强,对活性艳蓝KN R的进攻性优于对PolyR 478和比布列希猩红。     

垃圾渗滤液有机组分和氨氮在孔隙介质中的迁移特征

通过室内土柱淋滤模拟实验研究了垃圾渗滤液中有机组分(用CODCr表示)和氨氮在不同含水介质中的迁移规律和特征,并通过实验数据计算了延迟因子、COD衰减率和氨氮的单位质量介质吸附量等参数.结果显示,COD在中砂、细砂和粉土中迁移的延迟因子分别为1.13、1.23和1.24,表明有机物在三种实验介质中只发生轻微的延迟作朋;CODCr在三种介质中的自然衰减率分别为50.8%、55.2%和64.8%;氨氮的迁移由于吸附作用发生明显的延迟,其在上述三种介质中迁移的延迟因子和单位质量介质吸附最分别为3.30和194 mg·kg-1、3.91和223 mg·kg-1,以及5.12和280 mg·kg1;饱和条件下渗滤液中的氨氮较难发生硝化作用.上述结果可为评价垃圾渗滤液对地下水环境的影响提供技术参数.     

Photocatalytic degradation of ciprofloxacin in aqueous media: a short review

The frequent detection of antibiotics such as ciprofloxacin in surface and drinking waters around the world has attracted concern from various researchers. Such presence is an indication that the decontamination of water polluted by antibiotics is beyond the conventional treatment methods. However, among the different treatment methods that have been developed in the area of water purification, heterogeneous photocatalysis using semiconductor as a mediator has been rated as an efficient and a green wastewater treatment method. This is because, the process is effective in degrading and mineralizing organic pollutants, using UV or visible light. The present review paper covers a brief survey over a range of publications in the last decade, involving photocatalytic materials that have been employed in the purification of water contaminated by ciprofloxacin.     

Reliability of social media data in monitoring the global pet trade in ants

The global pet trade is a major risk to biodiversity and humans and has become increasingly globalized, diversified, digitalized, and extremely difficult to control. With billions of internet users posting online daily, social media could be a powerful surveillance tool. But it is unknown how reliably social media can track the global pet trade. We tested whether Instagram data predicted the geographic distribution of pet stores and the taxonomic composition of traded species in the emerging pet trade in ants (Hymenoptera, Formicidae). We visited 138 online stores selling ants as pets worldwide and recorded the species traded. We scraped ∼38,000 Instagram posts from ∼6300 users referencing ants as pets and analyzed comments on post and geolocation (available for ∼1800 users). We tested whether the number of Instagram users predicted the number of ant sellers per country and whether the species referenced as pets on Instagram matched the species offered in online stores, with a particular focus on invasive species. The location of Instagram users referencing ants as pets predicted the location of ant sellers across the globe (R² = 0.87). Instagram data detected 439 of the 631 ant species traded in online stores (70%), including 59 of the 68 invasive species traded (87%). The number of Instagram users referencing a species was a good predictor of the number of sellers offering the species (R² = 0.77). Overall, Instagram data provided affordable and reliable data for monitoring the emerging pet trade in ants. Easier access to these data would facilitate monitoring of the global pet trade and help implement relevant regulations in a timely manner.     

Characteristic volume fractions of different grains in porous media for anomalous dispersion

Anomalous solute transport in porous media is an important issue in groundwater research. In this paper, we explore the relationship between the anomalous solute transport and the volume fractions of different grains in the porous media. Via simulation, we find that there is a maximum and a minimum in the degree of anomalous transport when changing the volume fractions of different grains. Moreover, the characteristic volume fractions corresponding to the anomalous transport maximum and minimum vary little with the flow field and diffusion coefficient of the solute. We also find that the volume fraction corresponding to the most anomalous dispersion is close to the threshold of the site percolation for simple-cubic networks.     

Analysis of the insecticide hexachlorocyclohexane isomers in biological media. A review

Hexachlorocyclohexane (HCH) and lindane were used as insecticides since 1949s. They were progressively banished in most of the nations in the world, because of the their persistence and their potential toxicity and carcinogenicity. They are still occurring in the environment. These insecticides and isomers (α-HCH, β-HCH…) were detected in all media, e.g. soils, sediments, potable water, vegetables, human and animal tissues and air. In this review, we present the synthesis of the analytical procedures and materials used to determine the HCHs isomers in media such as vegetables, human tissues, animals tissues and rations. The analytical techniques which are presented permit to select the best analytical conditions to detect HCHs isomers.     

Transport of antibiotic resistance plasmids in porous media and the influence of surfactants

Transport of engineered antibiotic resistance plasmids in porous media has been reported to potentially cause significant spreading of antibiotic resistance in the environment. In this work, transport of an indigenous resistance plasmid pK5 in porous media was investigated through packed column experiments. At identical ionic strengths in CaCl₂ solutions, the breakthroughs of pK5 from soil columns were very close to those from quartz sand columns, indicating that transport of pK5 in quartz sand and soil was similar. A similarity in transport behavior was also found between pK5 and an engineered plasmid pBR322 that has approximately the same number of base pairs as pK5. The influence of surfactants, a major group of constituents in soil solutions, was examined using an engineered plasmid pcDNA3.1(+)/myc-His A. The impact of an anionic surfactant, sodium dodecyl sulfate (SDS), was negligible at concentrations up to 200 mg·L^–1. Cetyltrimethyl ammonium bromide (CTAB), a cationic surfactant, was found to significantly enhance plasmid adsorption at high concentrations. However, at environmentally relevant concentrations (<1 mg·L^–1), the effect of this surfactant was also minimal. The negligible impact of surfactants and the similarity between the transport of engineered and indigenous plasmids indicate that under environmentally relevant conditions, indigenous plasmids in soil also have the potential to transport over long distances and lead to the spreading of antibiotic resistance.

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The role of social media for sustainable development in mountain region tourism in Pakistan

This research letter focuses on tourist behavior and tourism business operators’ contributions to rural mountain region economic growth and sustainable development when using social media. Data were collected from 43 interviews from different tourism business operators, and a questionnaire survey of 576 tourists from the Gilgit-Baltistan, Pakistan. Drawing on development communication theory, the study reveals that there is a positive relationship between the tourists’ intentions and rural mountain region sustainable development. The study also reveals that most tourists are willing to pay more taxes when touring mountain regions. The real business outcomes from tourism business operators show that rural mountain region tourism creates better employment opportunities for the rural population. All tourists demonstrated the motivation to take part in rural mountain region sustainable development while touring rural locations. The study also offers policy implications.     

Estimating the extent and structure of trade in horticultural orchids via social media

The wildlife trade is a lucrative industry involving thousands of animal and plant species. The increasing use of the internet for both legal and illegal wildlife trade is well documented, but there is evidence that trade may be emerging on new online technologies such as social media. Using the orchid trade as a case study, we conducted the first systematic survey of wildlife trade on an international social‐media website. We focused on themed forums (groups), where people with similar interests can interact by uploading images or text (posts) that are visible to other group members. We used social‐network analysis to examine the ties between 150 of these orchid‐themed groups to determine the structure of the network. We found 4 communities of closely linked groups based around shared language. Most trade occurred in a community that consisted of English‐speaking and Southeast Asian groups. In addition to the network analysis, we randomly sampled 30 groups from the whole network to assess the prevalence of trade in cultivated and wild plants. Of 55,805 posts recorded over 12 weeks, 8.9% contained plants for sale, and 22–46% of these posts pertained to wild‐collected orchids. Although total numbers of posts about trade were relatively small, the large proportion of posts advertising wild orchids for sale supports calls for better monitoring of social media for trade in wild‐collected plants.