Organophosphates and carbamates are pesticides whose acute toxicities are caused by inhibition of acetylcholinesterase. A liquid chromatography–mass spectrometry/mass spectrometry method was developed and validated for the quantification of 16 organophosphate and carbamate insecticides in human serum. Nonpolar and polar pesticides were simultaneously extracted from serum samples using a simple and fast monolithic spin column procedure using mixed-mode C-C18 cartridges. Recovery was achieved in the range 11.9–99.2 %. Chromatography was carried out on an InertSustain® C18 HP 3 μm analytical column with gradient elution. Mass spectrometric analysis was performed using an Agilent 6410 Triple Quad Tandem mass spectrometer coupled with an electrospray ionization source in the positive ion mode. The assay was validated over a large concentration range and the limits of detection for all compounds ranged from 0.1 to 50 ng mL−1. The precision for both intra- and inter-day determination of all analytes was found to be acceptable (< 12.9 %) and no significant matrix effect was observed. The developed method was effectively applied to clinical samples from patients presenting at hospital with symptoms of acute intentional organophosphate or carbamate poisoning, demonstrating its applicability to diagnostic applications.
The mammalian tongue has evolved for specialized functions in different species. The structure of its papillae tells about the animal's diet, habit, and taxonomy. The opossum has four kinds of lingual papillae (filiform, conical, fungiform, vallate). Scanning electron microscopy of the external features, connective tissue cores, and corrosion casts of the microvasculature show the filiform papillae have a spearhead-like main process and spiny accessory processes around the apical part of the main process. The shape and number of both processes depend on their position on the tongue. On the apex, the main processes have shovel-like capillary networks and the accessory processes have small conical networks. On the lingual radix, the processes have small capillary loops. In the patch region, conical papillae have capillaries arranged as a full sail curving posteriorly. The fungiform papillae are scattered among the filiform papillae and have capillary baskets beneath each taste bud. Giant fungiform papillae on the tongue tip are three to four times larger than the ones on the lingual body. Capillaries of giant papillae form a fan-shaped network. The opossum has three vallate papillae arranged in a triangle. Their tops have secondary capillary loops but not their lateral surfaces. Mucosal folds on the posterolateral border have irregular, fingerlike projections with cylindrical capillary networks. These findings and the structure of the rest of the masticatory apparatus suggest the lingual papillae of opossum have kept their ancestral carnivorous features but also developed the herbivore characteristics of other marsupials. 相似文献
We propose a modified version of configuration analysis (CA) for the fragment interaction in conjunction with Kitaura’s fragment molecular orbital (FMO) scheme. The proposal is abbreviated as CAFI. The MO sets of fragments are merged and then orthonormalized by the use of a weighted Löwdin orthonormalization. The energy calculation is performed with the concurrent electron relaxation functional (CERF). The relaxation energy is obtained in an orbital-wise fashion and is distinguished as the charge-transfer and the polarization. The utility of CAFI is demonstrated through test calculations on hydrogen-bonding systems. 相似文献
Phenanthrene was adsorbed from ethanol solution to the surface of single wall carbon nanotubes, which were previously physically and chemically characterized. Different anionic surfactants were added in the solutions to enhance the phenanthrene solubility and apparently have also improved the dispersion of two respective nanotube samples used. Adsorbed amount was determined through the concentration difference measured by UV-visible spectrophotometry. Results suggest that adsorption of phenanthrene is extremely improved in the case of nanotube purified with higher quality. These findings were confirmed by X-ray photoelectron spectroscopy. The influence of the surfactant on the adsorption kinetics of phenanthrene is suggested to be significant as well. 相似文献
Summary Every two homomorphisms from the fundamental group of an oriented closed surface of genus 2 into the group of orientation preserving homeomorphisms (resp.C2 diffeomorphisms) of the circle are shown to be mutually semi-conjugate (resp. topologically conjugate), provided their Euler numbers attain the minimal value (or the maximal value) allowed by the Milnor-Wood inequality. 相似文献
Acetobacter xylinum, which normally produces ribbon-like microfibrils of cellulose I, occasionally synthesizes a band-like cellulose (native band, or NB) having a cellulose II crystal structure with a putative folded-chain structure. In contrast to a previous finding of NB production by a mutant strain of A. xylinum, we found that the wild-type strain also produced NB when incubated on agar plate medium. Incubation of the same strain in liquid media of varying viscosity with the addition of polyethylene glycol (PEG) resulted in the production of normal ribbon at low viscosities and NB at high viscosities. This behaviour was independent of the molecular weight of PEG and there seemed to be a critical level in viscosity for the switching from ribbon production to NB production. These findings strongly suggest that NB production is induced by a low mobility of cells in the culture medium due to physical constraints. 相似文献
A new sterically hindered tetradentate tripodal ligand (Me2-etpy) and its labeled analogue having deuterated methylene groups (d4-Me2-etpy) were synthesized, where Me2-etpy is bis(6-methyl-2-pyridylmethyl)(2-pyridylethyl)amine. Copper(I) complexes [Cu(Me2-etpy or d4-Me2-etpy)]+ (1 and 1-d4, respectively) reacted with dioxygen at -80 degrees C in acetone to give bis(mu-oxo)dicopper(III) complexes [Cu2(O)2(Me2-etpy or d4-Me2-etpy)2](2+) (1-oxo and 1-d4-oxo, respectively), the latter of which was crystallographically characterized. Unlike a bis(mu-oxo)dicopper(III) complex with a closely related Me2-tpa ligand having a 2-pyridylmethyl pendant, 1-oxo possessing a 2-pyridylethyl pendant is not fully formed even under 1 atm of O2 at -80 degrees C and is very reactive toward the oxidation of the supporting ligand. Thermal decomposition of 1-oxo gave an N-dealkylated ligand in yield approximately 80% based on a dimer and a corresponding aldehyde. The deuterated ligand d4-Me2-etpy greatly stabilizes the bis(mu-oxo)dicopper(III) complex 1-d4-oxo, indicating that the rate determining step of the N-dealkylation is the C-H bond cleavage from the methylene group. The reversible conversion between 1-d4 and 1-d4-oxo in acetone is dependent on the temperature, and the thermodynamic parameters (DeltaH and DeltaS) of the equilibrium were determined to be -53 +/- 2 kJ mol(-1) and -187 +/- 10 J mol(-1) K(-1), respectively. The effect of the 2-pyridylethyl pendant in comparison with the 2-pyridylmethyl and 6-methyl-2-pyridylmethyl pendants on the physicochemical properties of the copper(I) and bis(mu-oxo)dicopper(III) species is discussed. 相似文献