Reverse osmosis is an interesting process to eliminate organic solutes from distillery condensates before recycling them into the fermentation step. However, organic solutes transport phenomena through reverse osmosis membranes are specific. Rejection and sorption of five compounds were studied on a brackish water membrane. Acetic acid and 2,3-butanediol were not sorbed on the membrane while furfural and 2-phenylethanol presented strong sorption following the Langmuir pattern. These sorption effects coupled with solute molecular weight (MW) led to low rejections of acetic acid and furfural (30–60%) and high rejections of 2,3-butanediol and 2-phenylethanol (80–98%). With intermediate sorption and MW, butyric acid showed rejections between 70 and 80%. A modified solution-diffusion model was developed to take into account the sorption pattern and predict the concentration profile along the membrane on the retentate and permeate sides. Equilibrium properties were determined experimentally while transport properties were identified with data obtained from a synthetic condensate. This model was validated for various operating conditions with the synthetic and the industrial condensates. It was then used to simulate the influence of the recovery rate on the retentate and permeate concentrations. It showed the behavior differences between solutes with a linear sorption and solutes with a saturating sorption. 相似文献
Native mass spectrometry (MS) encompasses methods to keep noncovalent interactions of biomolecular complexes intact in the gas phase throughout the instrument and to measure the mass-to-charge ratios of supramolecular complexes directly in the mass spectrometer. Electrospray ionization (ESI) in nondenaturing conditions is now an established method to characterize noncovalent systems. Matrix-assisted laser desorption/ionization (MALDI), on the other hand, consumes low quantities of samples and largely tolerates contaminants, making it a priori attractive for native MS. However, so-called native MALDI approaches have so far been based on solid deposits, where the rapid transition of the sample through a solid state can engender the loss of native conformations. Here we present a new method for native MS based on liquid deposits and MALDI ionization, unambiguously detecting intact noncovalent protein complexes by direct desorption from a liquid spot for the first time. To control for aggregation, we worked with HUαβ, a heterodimer that does not spontaneously rearrange into homodimers in solution. Screening through numerous matrix solutions to observe first the monomeric protein, then the dimer complex, we settled on a nondenaturing binary matrix solution composed of acidic and basic organic matrices in glycerol, which is stable in vacuo. The role of temporal and spatial laser irradiation patterns was found to be critical. Both a protein-protein and a protein-ligand complex could be observed free of aggregation. To minimize gas-phase dissociation, source parameters were optimized to achieve a conservation of complexes above 50% for both systems.
A new, two-step synthesis of oxazolopyridines is described. The synthesis involving amide formation between o-aminopyridinols and aliphatic or aromatic carboxylic acids followed by condensation with hexachloroethane/triphenylphosphine takes place at room temperature and thereby gives mild access to all regioisomeric, 2-substituted oxazolopyridines in good yields. 相似文献
The performance of the Diffusive Gradients in Thin films (DGT) technique with Chelex®-100, Metsorb™ and Diphonix® as binding phases was evaluated in the vicinity of the former uranium mining sites of Chardon and L'Ecarpière (Loire-Atlantique department in western France). This is the first time that the DGT technique with three different binding agents was employed for the aqueous U determination in the context of uranium mining environments. The fractionation and speciation of uranium were investigated using a multi-methodological approach using filtration (0.45 μm, 0.2 μm), ultrafiltration (500 kDa, 100 kDa and 10 kDa) coupled to geochemical speciation modelling (PhreeQC) and the DGT technique. The ultrafiltration data showed that at each sampling point uranium was present mostly in the 10 kDa truly dissolved fraction and the geochemical modelling speciation calculations indicated that U speciation was markedly predominated by CaUO2(CO3)32−. In natural waters, no significant difference was observed in terms of U uptake between Chelex®-100 and Metsorb™, while similar or inferior U uptake was observed on Diphonix® resin. In turn, at mining influenced sampling spots, the U accumulation on DGT-Diphonix® was higher than on DGT-Chelex®-100 and DGT-Metsorb™, probably because their performance was disturbed by the extreme composition of the mining waters. The use of Diphonix® resin leads to a significant advance in the application and development of the DGT technique for determination of U in mining influenced environments. This investigation demonstrated that such multi-technique approach provides a better picture of U speciation and enables to assess more accurately the potentially bioavailable U pool. 相似文献
The Federal Bureau of Investigation (FBI) Laboratory is currently exploring needs and protocols for the storage of evidentiary
items contaminated with radioactive material. While a large body of knowledge on the behavior of storage polymers in radiation
fields exists, this knowledge has not been applied to the field of forensics and maintaining evidentiary integrity. The focus
of this research was to evaluate the behavior of several traditional evidentiary containment polymers when exposed to significant
alpha, beta, gamma, neutron and mixed radiation sources. Doses were designed to simulate exposures possible during storage
of materials. Several products were found to be poorly suited for use in this specific application based on standardized mechanical
testing results. Remaining products were determined to warrant further investigation for the storage of radiologically-contaminated
evidence. 相似文献