Toward a Novel Approach to Bis-β-Lactam Synthesis Using Vilsmeier Reagent as an Efficient Entity via Staudinger Cycloaddition Reaction. -Vilsmeier reagent is shown to act as acid activator reagent for the direct [2 + 2] ketene-imine cycloaddition of acetic acid (II) and bisimines (I). In all cases, the process affords cis,cis-bis-β-lactams (III) (8 examples). -(MESHRAM*, J.; ALI, P.; TIWARI, V.; J. Heterocycl.

Significant concentrations of nitrite NO 2 -were produced from the photodegradation of humic substances (HS) isolated from a variety of natural waters in coastal North Carolina. Nitrite concentrations were 40-118% higher after light exposure relative to initial levels, while no statistical differences were observed in dark controls before and after irradiation. The amount of nitrite produced upon irradiation was positively correlated to the concentration of HS added (r ) 0.97, p < 0.001) and to the length of irradiation. The average production rate, normalized to both humic substance concentration and time of light exposure, for all HS studied ranged from 9.7 to 17 [nM (W-h) -1 m -2 mg -1 ] × 10 5 . This translates into an average yearly nitrite production of 2 × 10 6 mol yr -1 in the top one meter of Onslow Bay. When natural waters were irradiated, changes in nitrite were influenced by both initial nitrite and humic substance concentrations. The rate of nitrite photochemical formation in typical coastal waters (4 nM h -1 ) was smaller than its direct photolysis rate (23 nM h -1 ) and smaller than reported rates of ammonium generation via DOM photodegradation (50 nM h -1 ) and of the same order of magnitude as NH 4 + incorporation during humification (1 nM h -1 ). The photochemical release of biologically available nitrite from biologically refractory humic substances has significant implications with respect to nitrite biogeochemistry and N cycling in natural waters and suggests HS bound N is more biogeochemically labile than previously thought.

Microplastics are ingested by estuarine species, yet the trophic transfer of microplastics from common single-celled prey to larval predator has never been investigated in estuarine systems. Furthermore, the influence of microplastic-associated contaminants on trophic transfer in estuarine systems is unknown. This study provides the first evidence for the trophic transfer of microplastics in a model food chain relevant to North American estuaries, as well as the potential impacts of a sorbed legacy pollutant on microplastic trophic transfer. Our study is also the first to use a unicellular microzooplankton as prey in a microplastic trophic transfer study. Microzooplankton are key microbial consumers and play an important role in estuarine food webs. We also demonstrate the negative impacts of microplastic ingestion on growth in larval fish. AbstractMicroplastics are of increasing concern as they are readily ingested by aquatic organisms. This study investigated microplastic trophic transfer using larval inland silversides (Menidia beryllina) (5 d posthatch) and unicellular tintinnid (Favella spp.) as a model food chain relevant to North American estuaries. Low-density polyethylene microspheres (10-20 μm) were used to compare direct ingestion of microplastics by larval fish and trophic transfer via tintinnid prey. Dichlorodiphenyltrichloroethane (DDT)-treated microspheres were used to determine sorbed pollutant effects on microplastic ingestion. Larval fish exposed directly to microspheres

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