Preparation and evaluation of molecularly imprinted solid-phase micro-extraction fibers for selective extraction of phthalates in an aqueous sample

A novel molecularly imprinted polymer (MIP) that was applied to a solid-phase micro-extraction (SPME) device, which could be coupled directly to gas chromatograph and mass spectrometer (GC/MS), was prepared using dibutyl phthalate (DBP) as the template molecule. The characteristics and application of this fiber were investigated. Electron microscope images indicated that the MIP-coated solid-phase micro-extraction (MI-SPME) fibers were homogeneous and porous. The extraction yield of DBP with the MI-SPME fibers was higher than that of the non-imprinted polymer (NIP)-coated SPME (NI-SPME) fibers. The MI-SPME fibers had a higher selectivity to other phthalates that had similar structures as DBP. A method was developed for the determination of phthalates using MI-SPME fibers coupled with GC/MS. The extraction conditions were optimized. Detection limits for the phthalate samples were within the range of 2.17-20.84 ng L⁻¹. The method was applied to five kinds of phthalates dissolved in spiked aqueous samples and resulted in recoveries of up to 94.54-105.34%, respectively. Thus, the MI-SPME fibers are suitable for the extraction of trace phthalates in complicated samples.     

Gold-nanoparticle-stabilized pluronic micelles exhibiting glutathione triggered morphology evolution properties

Nanocomposites constructed from metallic nanoparticles and amphiphilic copolymers have attracted substantial interest for various potential applications. Here we report on the nanocomposites prepared through cross-linking pluronic micelles with gold nanoparticles. The covalent binding of gold nanoparticles onto the micelles and the thermoresponsibility of the system was followed via ultraviolet-visible spectroscopy, dynamic light scattering, transmission electron microscopy, and fluorescence spectroscopy. The gold-nanoparticle-stabilized pluronic micelles can take thiol-exchange reaction with glutathione and their morphology spontaneously evolved and reassembled into large "vesicular"-like nanocapsules. Obvious temperature responsibility was followed in the gold-nanoparticle-stabilized pluronic micelles system and also the glutathione triggered nanocapsules systems. It is believed that the high stability and glutathione responsibility of the Au-NPs shell-cross-linked micelles allowed for high potential in drug delivery and biosensors.     

Free radical scavenging activity and characterization of sesquiterpenoids in four species of Curcuma using a TLC bioautography assay and GC-MS analysis

The sesquiterpenoids are one of major groups of antioxidants in Curcuma besides curcuminoids. However, the real substances contributing to the antioxidant activity are still unknown. In this paper, the antioxidant activity of sesquiterpenoids in four species and two essential oils from Curcuma genus was determined and compared based on TLC separation and DPPH bioautography assay. Their antioxidant capacities were quantitatively evaluated using densitometry with detection at 530 nm (λ(reference )= 800 nm) using vitamin C as reference. The results showed that Curcuma longa rhizomes had the highest antioxidant capacity while C. phaeocaulis presented the lowest one among the four species of Curcuma. Moreover, essential oil of C. wenyujin showed higher antioxidant potential than that of C. longa. The main TLC bands with antioxidant activity of the four species of Curcuma were collected and characterized using GC-MS, and thus curzerene, furanodiene, α-turmerone, β-turmerone and β-sesquiphellandrene were determined as major sesquiterpenoids with antioxidant activity in Curcuma.     

Safety properties of liquid state soft pack high power batteries with carbon-coated LiFePO4/graphite electrodes

The carbon-coated LiFePO₄ materials were synthesized, and their structure and morphology were characterized by X-ray diffraction and transmission electron microscopy. The safety and heating mechanism of the 066094-type liquid state soft pack high power batteries with carbon-coated LiFePO₄/graphite electrodes under abusive conditions, such as overcharge, overdischarge, and short current were extensively investigated. It was found that the increase in the temperature of the LiFePO₄/graphite high power batteries during overcharge was attributed to the reaction of the electrolyte decomposition and the Joule heat. The batteries were heated rapidly by the irreversible heat generated from the current passing through the electrodes during short current. The temperature rise of the batteries which were overdischarged to 0 V was mainly due to the Joule heat. The overdischarge at 1 C/0 V almost did not influence the cycling performance of the batteries. The batteries did not fire, smoke, and explode under the above-mentioned abusive conditions. Therefore, the 066094-type liquid state soft film pack high power batteries with carbon-coated LiFePO₄/graphite electrodes showed excellent safety performance.     

Theoretical study of spin–orbit coupling and kinetics in spin-forbidden reaction between Ta(NH2)3 and N2O

The activation mechanism of the nitrous oxide (N₂O) with the Ta(NH₂)₃ complex on the singlet and triplet potential energy surfaces has been investigated using the hybrid exchange correlation functional B3LYP. The minimum energy crossing point (MECP) is located by using the methods of Harvey et al. The rate-determining step of the N–O activation reaction is the intersystem crossing from ¹ 2 to ³ 2. The reacting system will change its spin multiplicities from the singlet state to the triplet state near MECP-1, which takes place with a spin crossing barrier of 32.5 kcal mol^?1, and then move on the triplet potential energy surface as the reaction proceeds. Analysis of spin–orbit coupling (SOC) using localized orbitals shows that MECP-1 will produce the significant SOC matrix element, the value of SOC is 272.46 cm^?1, due to the electron shift between two perpendicular π orbitals with the same rotation direction and the contribution from heavy atom Ta. The rate coefficients are calculated using Non-adiabatic Rice-Ramsperger-Kassel-Marcus (RRKM). Results indicate that the coefficients, k(E), are exceedingly high, k(E) > 10¹² s^?1, for energies above the intersystem crossing barrier (32.5 kcal mol^?1); however, in the lower temperature range of 200–600 K, the intersystem crossing is very slow, k(T) < 10^?6 s^?1.     

The synthesis,X-ray crystal structure and optical properties of novel 1,3,5-triaryl pyrazoline derivatives

A series of novel 1,3,5-triaryl pyrazoline derivatives has been synthesized by the reaction of chalcone and 3-chloro-6-hydrazinylpyridazine in 47–82% yields. The structures of compounds obtained were determined by IR, ¹H NMR and HRMS spectra. Representatively, the spatial structure of compound 3d was determined by using X-ray diffraction analysis. Absorption and fluorescence spectral characteristics of the compounds were investigated in CHCl₃ by UV–vis absorption and emission spectra. The results showed that the absorption maxima of the compounds vary from 332 to 342 nm depending on the group bonded to benzene rings. The maximum emission spectra of compounds in CHCl₃ are dependent on groups in benzene ring in which a strong electron-donating group in benzene ring such as methoxyl group on C3 position of pyrazoline made the emission wavelength of 3e, 3f and 3g red shifted than that of compounds 3b, 3c and 3d with chlorine group. The intensity of absorption and fluorescence was also correlated with substituent on two aryl rings. In addition, the absorption spectra of these compounds change very little with increasing solvent polarity.     

Two 3-D supramolecular architecture based on the linkages of Co(II) complexes and lattice water molecules

Two new 3-D supramolecular compounds [Co(phen)(tdc)(H₂O)₃]·5H₂O (1) and [Co(phen)(Htdc)(H₂O)₃]·(Htdc)·2H₂O (2, phen = 1,10-phenanthroline, H₂tdc = thiophene-2,5-dicarboxylate) have been hydrothermally synthesized and structurally characterized. In 1, the neutral [Co(phen)(tdc)(H₂O)₃] complexes behave as pillars to join the water layers to make an overall 3-D supramolecular architecture by H-bond interactions. In 2, similar 2-D water layer is not observed, which could be due to one uncoordinated Htdc ligand instead of three lattice water molecules of 1. The thermal stabilities of 1 and 2 were investigated by thermogravimetric measurements.     

A new open tubular capillary microextraction and sweeping for the analysis of super low concentration of hydrophobic compounds

A sample pre‐concentration method based on the in‐line coupling of in‐tube solid‐phase microextraction and electrophoretic sweeping was developed for the analysis of hydrophobic compounds. The sample pre‐concentration and electrophoretic separation processes were simply and sequentially carried out with a (35%‐phenyl)‐methylpolysiloxane‐coated capillary. The developed method was validated and applied to enrich and separate several pharmaceuticals including loratadine, indomethacin, ibuprofen and doxazosin. Several parameters of microextration were investigated such as temperature, pH and eluant. And the concentration of microemulsion that influences separation efficiency and microextraction efficiency were also studied. Central composite design was applied for the optimization of sampling flow rate and sampling time that interact in a very complex way with each other. The precision, sensitivity and recovery of the method were investigated. Under the optimal conditions, the maximum enrichment factors for loratadine, indomethacin, ibuprofen and doxazosin in aqueous solutions are 1355, 571, 523 and 318, respectively. In addition, the developed method was applied to determine loratadine in rabbit blood sample.     

The application of fractional derivatives in stochastic models driven by fractional Brownian motion

In this paper, in order to establish connection between fractional derivative and fractional Brownian motion (FBM), we first prove the validity of the fractional Taylor formula proposed by Guy Jumarie. Then, by using the properties of this Taylor formula, we derive a fractional Itô formula for H∈[1/2,1), which coincides in form with the one proposed by Duncan for some special cases, whose formula is based on the Wick Product. Lastly, we apply this fractional Itô formula to the option pricing problem when the underlying of the option contract is supposed to be driven by a geometric fractional Brownian motion. The case that the drift, volatility and risk-free interest rate are all dependent on t is also discussed.