Cephalosporin-3'-diazeniumdiolates: Targeted NO-Donor Prodrugs for Dispersing Bacterial Biofilms

Just say NO to biofilms: NO-donors are used to disperse a bacterial biofilm so that co-administered antibiotics will kill the more susceptible unattached cells. The chemically stable cephalosporin-3'-diazeniumdiolate NO-donor prodrug is activated by bacterial β-lactamases and facilitates this two-step biofilm erradication.     

PIV analysis of merging flow in a simplified model of a rotary kiln

Rotary kilns are used in a variety of industrial applications. The focus in this work is on characterizing the non-reacting, isothermal flow field in a rotary kiln used for iron ore pelletization. A downscaled, simplified model of the kiln is experimentally investigated using particle image velocimetry. Five different momentum flux ratios of the two inlet ducts to the kiln are investigated in order to evaluate its effect on the flow field in general and the recirculation zone in particular. Time-averaged and phase-averaged analyses are reported, and it is found that the flow field resembles that of two parallel merging jets, with the same characteristic flow zones. The back plate separating the inlet ducts acts as a bluff body to the flow and creates a region of reversed flow behind it. Due to the semicircular cross-section of the jets, the wake is elongated along the walls. Conclusions are that the flow field shows a dependence on momentum flux ratio of the jets; as the momentum flux ratio approaches unity, there is an increasing presence of von Kármán-type coherent structures with a Strouhal number of between 0.16 and 0.18. These large-scale structures enhance the mixing of the jets and also affect the size of the recirculation zone. It is also shown that the inclination of the upper inlet duct leads to a decrease in length of the recirculation zone in certain cases.     

Lipase-catalyzed asymmetric acylation in the chemoenzymatic synthesis of furan-based alcohols

Eight racemic 1-(furan-2-yl)ethanols were prepared from the corresponding carbonyl compounds for enantioselective acylation studies, and seven of them were used in preparative-scale kinetic resolutions with Candida antarctica lipase B (Novozym 435) and vinyl acetate in dried diisopropyl ether. Mechanism-based competition between the (R)-acetate (enzymatic acylation product), vinyl acetate (added acylating reagent), and acetic acid (enzymatic hydrolysis product) toward CAL-B, together with the residual water of the lipase were shown to be potential reasons for side reactions, which affected the course of the kinetic resolution of 1-[5-(2-chlorophenyl) and (4-bromophenyl)furan-2-yl]ethanols. Clear effects were not observed with the other alcoholic substrates. Alcoholysis of the enantiomerically enriched (R)-acetates with methanol and CAL-B in diisopropyl ether was shown to be a potential method for the deprotection of the (R)-acetates and the formation of (R)-alcohols.     

The 2-phenylsulfonylethylcarbonyl (PSEC) group for the protection of the hydroxyl function

The PSEC group may be used to protect the hydroxyl function in conjunction with a variety of acid and base labile protecting groups; the PSEC group may be removed by treatment of triethylamine (15 equiv.) in dry pyridine solution within 20 h at 20°C while other base labile protecting groups remained intact.     

The application of 2-(4-chlorophenyl)-sulfonylethoxycarbonyl (CPSEC) group in the synthesis of a DNA segment using the phosphotriester approach

The new base labile CPSEC group has been successfully employed for the protection of the 5′-hydroxyl function to synthesize a “universal Stop codon” DNA sequence: ^5′d(TCAATCAATCA)^3′.     

A practical synthesis of D-erythro-sphingosine using a cross-metathesis approach

Starting from a vinylepoxide, a short and practical synthesis of D-erythro-sphingosine is described. The key transformations are a regioselective opening of the vinylepoxide and an E-selective cross-metathesis, affording the target molecule 5 in steps and 51% overall yield.     

Isolation and structure elucidation of a novel yellow pigment from the marine bacterium Pseudoalteromonas tunicata

The marine environment is a major source for many novel natural compounds. A new yellow pigment has been isolated from the marine bacterium P. tunicata and identified as a new member of the tambjamine class of compounds. The structural identification was achieved by a combination of 1D and 2D-NMR spectroscopy and high resolution mass spectrometry data.     

Selective determination of acidic pharmaceuticals in wastewater using molecularly imprinted solid-phase extraction

The determination of acidic pharmaceuticals, such as non-steroidal anti-inflammatory drugs NSAIDs and clofibric acid (metabolite of clofibrate), at low ng L⁻¹ levels in wastewater requires highly selective and sensitive analytical procedures. The removal of matrix components during sample preparation results in significant benefits towards reducing the matrix effects during LC-MS analysis. Therefore this work describes a simple method to enrich and clean up NSAIDs and clofibric acid from sewage water using molecularly imprinted solid-phase extraction (MISPE). Final analysis was performed by liquid chromatography-tandem mass spectrometry. The performance of this method has been evaluated in fortified tap and sewage water in terms of recovery, precision, linearity, and method quantification limit. Recovery for all compounds ranged in all matrices between 84 and 116% with intra-day R.S.D. values below 11.5%. Matrix effect evaluation demonstrated that even complex sample matrixes, such as pond or sewage water did not showed significant ion suppression/enhancement compared to tap water. The performance of the method was further emphasized by the study of pond water, which receives treated water from a sewage treatment plant in south Sweden. Raw sewage and treated water were also tested. In those samples, all acidic pharmaceuticals were detected in concentration above method quantification limits ranging from 5.1 to 5153.0 ng L⁻¹.     

Investigation of Post-Darcy Flow in Thin Porous Media

Transport in Porous Media - We present numerical simulations of post-Darcy flow in thin porous medium: one consisting of staggered arrangements of circular cylinders and one random distribution of...