Single over-the-counter medication tablets were analyzed in real time using Single Particle Aerosol Mass Spectrometry (SPAMS). Dual-polarity time-of-flight mass spectra were obtained for micrometer-sized single particles dislodged from a single tablet without destroying the shape or markings of each tablet. The solid tablet was placed in a modified-top glass vial and shaken to dislodge and introduce micrometer-sized particles into the SPAMS system. Unique spectra from these particles were obtained in less than 1 s for single tablets of aspirin, ibuprofen, pseudoephedrine, phenylephrine, loratadine, or diphenhydramine. The signals obtained allowed the non-destructive identification of an individual tablet in seconds. SPAMS presents an ideal system for high-throughput analysis of solid drugs. 相似文献
Poloxamers F88 (EO97PO39EO97) and P85 (EO27PO39EO27) are triblock copolymers of ethylene oxide (EO) and propylene oxide (PO), which have the same hydrophobic PO block. We studied aqueous solutions of these two copolymers by the conjoint use of differential scanning calorimetry (DSC), rheology, and small-angle X-ray scattering (SAXS). The results showed that the temperature-induced micellization of aqueous solutions of F88 and P85 was a progressive process followed by gelation for sufficiently concentrated samples. Gelation was due to the ordered packing of micelles under a hexagonal compact (HC) structure for P85 and a body-centered cubic (BCC) phase for F88. Importantly, the phase diagram of F88/P85 mixtures in water was elucidated and showed the destabilization of the HC phase upon addition of small amounts of F88. 相似文献
We study the effect of random on-site energies on the critical temperature of a non-interacting Bose gas on a lattice. In our derivation the on-site energies are distributed according a Gaussian probability distribution function having vanishing average and variance ν02. By using the replicated action obtained by averaging on the disorder, we perform a perturbative expansion for the Green functions of the disordered system. We evaluate the shift of the chemical potential induced by the disorder and we compute, for ν02 ? 1, the critical temperature for condensation. We find that, for large filling, disorder slightly enhances the critical temperature for condensation. 相似文献
Utilization of TEMPO-oxidized celluloses in bio-based nanocomposites is reported for the first time. TEMPO-oxidized wood pulps
(net carboxylate content 1.1 mmol/g cellulose) were fibrillated to varying degrees using a high intensity ultrasonic processor.
The degree of fibrillation was controlled by varying sonication time from 1 to 20 min. The sonication products were then characterized
independently and as fillers (5 wt% loading) in hydroxypropyl cellulose nanocomposite films. Nanofibril yields ranging from
11 to 98 wt% (on fiber weight basis) were obtained over the range of sonication times used. Suspension viscosities increased
initially with sonication time, peaked with gel-like behavior at 10 min of sonication and then decreased with further sonication.
The thermal degradation temperature of unfibrillated oxidized pulps was only minimally affected (6 °C decrease) by the fibrillation
process. Dynamic mechanical analysis of the nanocomposites revealed strong fibril-matrix interactions as evidenced by remarkable
storage modulus retention at high temperatures and a suppression of matrix glass transition at “high” (~5 wt%) nanofibril
loadings. Creep properties likewise exhibited significant (order of magnitude) suppression of matrix flow at high temperatures.
It was also believed, based on morphologies of freeze-fracture surfaces that the nanocomposites may be characterized by high
fracture toughness. Direct fracture testing will however be necessary to verify this suspicion. 相似文献
Like many other bacterial cell surfaces, the cell wall of Clostridium difficile is also encapsulated by a proteinaceous paracrystalline layer, the surface (S)-layer. In many bacterial species, the S-layer proteins (SLPs) have been shown to be glycosylated, whereas in other species glycosylation is absent. Unusually, the S-layer of C. difficile is composed of two distinct proteins, the high-molecular weight (HMW) and low-molecular-weight (LMW) SLPs. Previous investigations have reported that one or both of these SLPs are glycosylated, though no definitive study has been conducted. We have used a variety of mass spectrometric approaches to analyse SLPs from a number of strains of C. difficile for the presence of associated glycans. Analysis of intact SLPs by matrix assisted laser desorption/ionisation time of flight (MALDI-ToF) mass spectrometry demonstrated that the observed molecular masses matched the predicted masses of the LMW and HMW SLPs. Furthermore, analysis of Cyanogen bromide (CNBr) and tryptic peptides displayed no evidence of post-translational modification. In the first in-depth study of its kind, we unequivocally demonstrate that the S-layer proteins from the C. difficile strains investigated are not glycosylated. 相似文献
Performant reagentless electrochemiluminescent (ECL) (bio)sensors have been developed using polymeric luminol as the luminophore.
The polyluminol film is obtained by cyclic voltammetry (CV) on a screen-printed electrode either in a commonly used H2SO4 medium or under more original near-neutral buffered conditions. ECL responses obtained after performing polymerization either
at acidic pH or at pH 6 have been compared. It appears that polyluminol formed in near-neutral medium gives the best responses
for hydrogen peroxide detection. Polymerization at pH 6 by cyclic voltammetry gives a linear range extending from 8 × 10−8 to 1.3 × 10−4 M H2O2 concentrations. Based on this performant sensor for hydrogen peroxide detection, an enzymatic biosensor has been developed
by associating the polyluminol film with an H2O2-producing oxidase. Here, choline oxidase (ChOD) has been chosen as a model enzyme. To develop the biosensor, luminol has
been polymerized at pH 6 by CV, and then an enzyme-entrapping matrix has been formed on the above modified working electrode.
Different biological (chitosan, agarose, and alginate) and chemical (silica gels, photopolymers, or reticulated matrices)
gels have been tested. Best performances have been obtained by associating a ChOD-immobilizing photopolymer with the polyluminol
film. In this case, choline can be detected with a linear range extending from 8 × 10−8 to 1.3 × 10−4 M.
This paper is based on the results presented in a poster that received a Poster Award on the occasion of XIII International
Symposium on Luminescence Spectrometry in Bologna, Italy, on September, 7th-11th, 2008. 相似文献
A highly efficient synthesis of the potent and selective NK-1 receptor antagonist 1 is described. The key transformation involved the etherification reaction between cyclopentanol 12 and chiral imidate 30 which was catalyzed by HBF4 to initially give ether 14 as a 17:1 mixture of diastereomers and in 75% combined yield. The diastereoselectivity was upgraded to 109:1 by crystallization of the triethylamine solvate 44 which was isolated in 54% yield from 12. Mechanistic studies confirmed that the etherification reaction proceeds through an unprecedented S(N)2 reaction pathway under typical S(N)1 reaction conditions. 相似文献
This study reports the first PEO‐coated polymer nanoparticles synthesis by miniemulsion polymerization of nano‐emulsions prepared by the low‐energy emulsification method called EIP. The surfactant used was Brij 98, a PEO based non ionic commercial surfactant. The partial phase diagram of the system water/Brij 98/styrene was first determined. The Emulsion Inversion Point technique was then used on the water/Brij 98/styrene system to the formation of styrene‐in‐water nano‐emulsions. After miniemulsion polymerization, particle sizes as low as 36 nm were obtained. To the best of our knowledge, this method had not been used for polymerizable system up to now.
The insoluble organic matter (IOM) of three carbonaceous meteorites (Orgueil, Murchison and Tagish Lake meteorites) and three samples of cherts (microcrystalline SiO2 rock) containing microfossils with age ranging between 45 million years and 3.5 billion years is studied by electron paramagnetic resonance (EPR). The age of the meteorites is that of the solar system (4.6 billion years). The purpose of this work was to determine the EPR parameters, which allow us to discriminate between biogenic and extra terrestrial origin for the organic matter. Such indicators should be relevant for the controversy regarding the biogenicity of the organic matter in the oldest cheroot (3.5 billion years) and in Martian meteorites containing microbe-like microstructures. The organic matter of meteorites contains a high concentration of diradicaloid moieties characterised by a diamagnetic ground state S = 0 and a thermally accessible triplet state S = 1. The three meteorites exhibit the same singlet-triplet gap (ST gap) DeltaE approximately 0.1 eV. To the best of our knowledge, such diradicaloids are unknown in insoluble organic matter of terrestrial origin. We have also shown that the EPR linewidth of insoluble organic matter in cherts and coals decrease logarithmically with the age of the organic matter. We conclude from this result that the organic matter in the oldest cherts (3.5 billion years) has the same age as their SiO2 matrix, and is not due to a latter contamination by bacteria, as was recently found in meteoritic samples. 相似文献