Determination of saccharides in atmospheric aerosol using anion-exchange high-performance liquid chromatography and pulsed-amperometric detection

An improved method is described for the quantification of primary sugars, sugar alcohols and anhydrosugars in atmospheric aerosols, making use of separation by high-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection (PAD). Quartz fibre filters from high-volume samplers were extracted with water and the extract injected directly. Repeatability is typically 4% RSD, for e.g. levoglucosan at 50 ng m(-3) in air, better for winter levels around 700 ng m(-3). Limits of detection for individual sugars are in the range 0.02-0.05 microg mL(-1) in solution, corresponding to 2-5 ng m(-3) from a 20 m(3) air sample. The overlap of arabitol and levogluocosan is overcome by using a Dionex PA-1 column, with appropriate control of eluent composition, and peak deconvolution software, allowing quantification of both sugars in difficult summer samples containing low-levels of levoglucosan. Analysis of a set of ambient aerosol samples by both GC-flame ionization detection and HPAEC-PAD shows good agreement. The new method has the advantage of requiring no sample pretreatment or derivatization and is thus well suited to handling large numbers of samples.     

Chain confinement promotes β-phase formation in polyfluorene-based photoluminescent ionogels

The synthesis of photoluminescent conjugated polymer silica ionogels using sol-gel chemistry is described. Cooperative self-assembly of an ionic liquid, the silica precursor and poly(9,9-dioctylfluorene) (PFO) via hydrogen bonding and π-stacking interactions drives formation of the PFO β-phase.     

Integral resource capacity planning for inpatient care services based on bed census predictions by hour

The design and operations of inpatient care facilities are typically largely historically shaped. A better match with the changing environment is often possible, and even inevitable due to the pressure on hospital budgets. Effectively organizing inpatient care requires simultaneous consideration of several interrelated planning issues. Also, coordination with upstream departments like the operating theatre and the emergency department is much-needed. We present a generic analytical approach to predict bed census on nursing wards by hour, as a function of the Master Surgical Schedule and arrival patterns of emergency patients. Along these predictions, insight is gained on the impact of strategic (ie, case mix, care unit size, care unit partitioning), tactical (ie, allocation of operating room time, misplacement rules), and operational decisions (ie, time of admission/discharge). The method is used in the Academic Medical Center Amsterdam as a decision-support tool in a complete redesign of the inpatient care operations.     

Ethylation of methylarsenic(III) compounds by sodium tetraethylborate

The compounds MeAsBr₂ and Me₂AsBr at concentrations of (1–5) × 10^?3 M in acetone solution are ethylated in high yield by NaBEt₄ to MeEt₂As and Me₂EtAs, as shown by ¹H NMR spectroscopy. The extents of ethylation of MeAs²⁺ and Me₂As⁺ (expressed as ions, by convention) in aqueous acid solutions [at concentrations of (5–20) × 10^?6 M ] were investigated using cold trap/AA and GC AA procedures. The species Me₂As⁺ was ethylated (to give Me₂EtAs) in good yield (88%); in contrast, MeAs²⁺ produced the volatile trialkylarsine, MeEt₂As, in poor yield (30%). No volatile trialkylarsine could be obtained on treating inorganic arsenic(III) (As³⁺) solutions with NaBEt₄.     

Systematic evolution from uranyl(VI) phosphites to uranium(IV) phosphates

Six new uranium phosphites, phosphates, and mixed phosphate-phosphite compounds were hydrothermally synthesized, with an additional uranyl phosphite synthesized at room temperature. These compounds can contain U(VI) or U(IV), and two are mixed-valent U(VI)/U(IV) compounds. There appears to be a strong correlation between the starting pH and reaction duration and the products that form. In general, phosphites are more likely to form at shorter reaction times, while phosphates form at extended reaction times. Additionally, reduction of uranium from U(VI) to U(IV) happens much more readily at lower pH and can be slowed with an increase in the initial pH of the reaction mixture. Here we explore the in situ hydrothermal redox reactions of uranyl nitrate with phosphorous acid and alkali-metal carbonates. The resulting products reveal the evolution of compounds formed as these hydrothermal redox reactions proceed forward with time.