Polyamide as an efficient sorbent for simultaneous interference-free determination of three Sudan dyes in saffron and urine using high-performance liquid chromatography-ultra violet detection北大核心CSCD

With polyamide( PA)as an efficient sorbent for solid phase extraction( SPE)of Sudan dyes II,III and Red 7B from saffron and urine,their determination by HPLC was performed. The optimum conditions for SPE were achieved using 7 mL methanol/water( 1:9,v/v,pH 7)as the washing solvent and 3 mL tetrahydrofu-ran for elution. Good clean-up and high( above 90%)recoveries were observed for all the analytes. The opti-mized mobile phase composition for HPLC analysis of these compounds was methanol-water( 70:30,v/v). The SPE parameters,such as the maximum loading capacity and breakthrough volume,were also determined for each analyte. The limits of detection( LODs),limits of quantification( LOQs),linear ranges and recoveries for the analytes were 4. 6-6. 6 μg/L,13. 0-19. 8 μg/L,13. 0-5 000 μg/L( r2> 0. 99)and 92. 5% -113. 4%,respec-tively. The precisions( RSDs)of the overall analytical procedure,estimated by five replicate measurements for Sudan II,III and Red 7B in saffron and urine samples were 2. 3%,1. 8% and 3. 6%,respectively. The developed method is simple and successful in the application to the determination of Sudan dyes in saffron and urine sam-ples with HPLC coupled with UV detection.     

Hydrazone- and hydrazide-containing N-substituted glycines as peptoid surrogates for expedited library synthesis: application to the preparation of Tsg101-directed HIV-1 budding antagonists

Replacing the Pro6 in the p6(Gag)-derived 9-mer "P-E-P-T-A-P-P-E-E" with N-substituted glycine (NSG) residues is problematic. However, incorporation of hydrazone amides ("peptoid hydrazones") can be readily achieved in library fashion. Furthermore, reduction of these hydrazones to N-substituted "peptoid hydrazides" affords a facile route to library diversification. This approach is demonstrated by application to Tsg101-binding compounds designed as potential HIV budding antagonists. [reaction: see text]     

Reaching for two new stable ambiphilic quinoline‐derived N‐heterocyclic carbenes at DFT level

A detailed investigation on the thermodynamic and kinetic stability of four carbenic tautomers of quinoline 1 , including quinoline‐2‐ylidene 2 , quinoline‐3‐ylidene 3 , quinoline‐4‐ylidene 4 , and 3,4‐dihydroquinoline‐4‐ylidene 5 , reveals that singlet planar six‐membered ring N‐heterocyclic carbenes (NHCs) 2 and 4 have less stability than Arduengo type NHC but seems to have enough conceivably for reaching at B3LYP/aug‐cc‐pVTZ//B3LYP/6–31+G* and B3LYP/6–311++G**//B3LYP/6–31+G* levels. All these six‐membered NHCs are extremely ambiphilic with the more nucleophilic and electrophilic characters compared to the Arduengo type one. The aromaticity of singlet 2 and 4 is a significant contributor to their stability which is confirmed through their Nucleus‐independent chemical shift(1)_zz values. Finally, among 2–5 , the normal NHC 2 is thermodynamically preferred but the remote NHC 4 is kinetically proffered over the other isomeric carbenes. The effects of different N‐ or C‐substituted NHCs of 2 are studied using appropriate isodesmic reactions. The trimethylsilyl substituent exhibits slightly larger carbene stabilization in quinoline‐derived NHCs than the pyridine analogue. © 2014 Wiley Periodicals, Inc.     

One-Pot,Three-Component Synthesis of Pyrimido[4,5-b]quinoline-tetraone Derivatives in Water

Novel pyrimido[4,5-b]quinoline-tetraones were prepared by the three-component reaction of 2-hydroxynaphthalene-1,4-dione, 6-amino-uracils, and aromatic aldehydes in aqueous media and catalyzed by p-toluenesulfonic acid. This protocol provides a simple one-step procedure with the advantages of easy workup, good yield of products, and environmental friendliness.     

Synthesis and Characterization of Mesoporous Titanosilicate as an Adsorbent for Toxic Metal Ions

Hexagonal mesoporous titanosilicates (Ti‐MCM‐41) have been prepared using cetyltrimethylammonium bromide (CTAB) as the structure directing agent under the mild alkaline conditions. Powder X‐ray diffraction, nitrogen gas sorption, FTIR spectroscopy and thermogravimetry analysis of samples have confirmed that well ordered MCM‐41 type mesoporous materials were prepared. The potential of removing toxic metal ions from waste waters using mesoporous titanosilicates was evaluated. Separation of Co^II‐U^VI, Cs^I‐U^VI and Sm^III‐U^VI has been developed on columns of this adsorbent.     

B12N12 Nano-cage as Potential Sensor for NO2 Detection

The NO₂ molecule adsorption on B₁₂N₁₂ nano-cage was investigated using density func-tional theory calculations in terms of adsorption energy, HOMO/LUMO energy gap (Eg) changes, charge transfer, structural deformation, etc. Furthermore, some aspects of stability and properties of B₁₂N₁₂ including calculation of binding electronic and Gibbs free energies, density of states, and molecular electrostatic potential surfaces are investigated. Three pos-sible configurations for NO₂ adsorption on the B₁₂N₁₂ nano-cage are energetically found. Interestingly, the results reveals that the Eg of B₁₂N₁₂ cluster is very sensitive to the pres-ence of NO₂ molecules as its value reduces from 6.84 eV in free cluster to 3.23 eV in the most stable configuration of NO₂/cluster complex. This phenomenon dramatically increases the electrical conductivity of the cluster, suggesting that the B₁₂N₁₂ nano-cluster may be potential sensor for NO₂ gaseous molecule detection.     

Influence of growth phase on the essential oil composition and antimicrobial activities of Satureja hortensis

The variations in quantity and quality of essential oils (EOs) from the aerial parts of cultivated Satureja hortensis were determined at different stages of harvesting. The EOs of air-dried samples were obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry (GC/MS). The antimicrobial activity of the EOs was investigated by broth microdilution methods. The amount of EOs (w/w, %) were 2.3, 2.5, 2.0, and 1.8% at floral budding, full flowering, immature fruit, and ripened fruit stages, respectively. gamma-Terpinene was the major compound of the EO at all developmental stages, except the ripened fruit stage when it was replaced by carvacrol (46.4%). The EOs exhibited strong antibacterial activities against the tested bacteria. Moreover, the EOs either inhibited or killed the examined yeasts at concentrations ranging from 0.03-8.0 microL/mL. Considering the wide range of antimicrobial activities of the examined EOs, they might have potential to be used in the management of infective agents.