Determination of thorium with DBF-arsenaz by flow-injection analysis

A sensitive,selective,rapid,simple,and convenient method for the determination of thoriumwas developed.The method was based on the color reaction of thorium with DBF-arsenazo in astrong acidic medium (4 mol/L HCI).The flow-injection technique was used with an automated flow-injection analyzer.Beer's law was obeyed in the range of 0—1.4 μg/mL.The relative standarddeviations were less than 1%.     

Inclusion of acaricides by complexation withβ-cyclodextrin

Many synthetic pesticides (herbicides, insecticides, fungicides etc.) can be complexed with cyclodextrins. The inclusion complexes of acaricides such as Fenson, Chlorfenson and Genite were prepared. The formation of inclusion complexes was established by UV and X-ray diffraction techniques. The host-to-guest ratio was determined by UV spectral and GLC methods.This paper is dedicated to Professor A.B. Kulkarni on his 75th birthday.     

Liposome solubilization induced by complexation with dimeric β-cyclodextrin

Dimeric β-cyclodextrins (β-CD) were prepared from the reaction of native β-CD with epichlorohydrin under basic conditions, and the effects on the diacetylene (DA) and polydiacetylene (PDA) liposomes have been investigated. Vesicular DA was solubilized in the presence of dimeric β-CD with the consequent inhibition of polymerization. The result is attributed to the formation of a complex between dimeric β-CD and DA liposomes, and it is clearly differentiated from that of monomeric β-CD. Furthermore, the ordered supramolecular structure of PDA was perturbed by the dimeric β-CD, which was detected from the visible color change. Finally, the morphological characteristics and size of PDA in the absence and presence of dimeric β-CD were examined using transmission electron microscopy and dynamic light scattering The results show fused structure of size more than 200 nm along with the deformation of the vesicles, and they represent a novel phenomenon of liposome structure induced by complexation with dimeric β-CD. The evaluated physicochemical characteristics can be applied to the development of carbohydrate-based detergents.     

Hybrid supramolecular hydrogels induced by Au nanoparticles protected with MPEG-b-PCL copolymers with α-cyclodextrin

To fabricate supramolecular hydrogel hybridised with well-dispersed gold nanoparticles (AuNPs), water-soluble AuNPs protected with methoxy poly(ethylene glycol)-b-poly(?-caprolactone) (MPEG-b-PCL) self-assembled monolayers (MPEG-b-PCL/AuNPs) were synthesised and used as guest molecules to interact with α-cyclodextrin (α-CD) in aqueous solutions. Transmission electron microscopy measurement results showed that the diameter of the AuNPs produced was about 6–10 nm with a narrow particle size distribution, and stained MPEG-b-PCL/AuNPs micelles made in water clearly displayed the formation of a core-shell structure with a single gold core per micelle. X-ray diffraction measurement results confirmed that there existed the characteristic peaks of both AuNPs and polypseudorotaxanes formed via the inclusion complexation of MPEG-b-PCL moieties with α-CD in as-obtained hydrogels. UV–visible spectra displayed that the same surface plasma resonance absorption peaks appeared at 526 nm for both aqueous dispersion of MPEG-b-PCL/AuNPs and resultant hybrid hydrogel with α-CD. Rheological measurements showed that the hybrid hydrogel has a lower mechanical strength and viscosity, and a relatively prolonged gelation time in comparison with the corresponding native hydrogel. The mechanical strength of the hydrogel nanocomposites could be tailored by modulating the concentration of MPEG-b-PCL/AuNPs and α-CD as well as the composition of MPEG-b-PCL/AuNPs.     

Synthesis of Benzoxazolinone by Selenium-Catalyzed Carbonylation with Carbon Monoxide

Ｂｅｎｚｏｘａｚｏｌｉｎｏｎｅｓａｒｅａｋｎｏｗｎｃｌａｓｓｏｆｃｏｍｍｅｒ ｃｉａｌｌｙａｖａｉｌａｂｌｅｃｏｍｐｏｕｎｄｓｔｈａｔａｒｅｗｉｄｅｌｙｕｓｅｄｉｎａ ｇｒｉｃｕｌｔｕｒｅａｎｄｉｎｄｕｓｔｒｙ .Ｔｒａｄｉｔｉｏｎａｌｌｙ ,ｔｈｅｓｅｃｏｍ ｐｏｕｎｄｓａｒｅｍａｄｅｂｙｔｈｅｉｎｔｒａｍｏｌｅｃｕｌａｒｃｙｃｌｉｚａｔｉｏｎｏｆｐｈｅｎｙｌＮ (2 ｈｙｄｒｏｘｙｐｈｅｎｙｌ)ｃａｒｂａｍａｔｅｗｈｉｃｈｉｓｐｒｏｄｕｃｅｄｂｙｔｈｅｒｅａｃｔｉｏｎｏｆｏ ａｍｉｎｏｐｈｅｎｏｌｗｉｔ…     

Evidence of DNA-Ligand Binding with Different Modes Studied by Spectroscopy

The study of DNA (deoxyribonucleic acid) conformational changes upon ligand bindingis a hot spot in the frontier field of relative research in chemical biological or medicinalareas,1-5. The structual changes of DNA in response to ifferent bound ligands haveattracted continuing at'tention in the medicinal design of anticancer and/or anti-AIDSdrugs. TO fuFther reveal the relationship between the specially functional structure ofligands and the conformational changes of DNA, the binding mod…     

Competing binding of metal ions with protein studied by microdialysis

A method has been established to study the competing binding of metal ions with protein by a combined technique of microdialysis with high performance liquid chromatography (HPLC). Ni2+, Cd2+, Zn2+, Cu2+ and human serum albumin (HSA) were chosen as model metal ions and protein. The experimental results show that Ni2+ and Cu2+ share a common primary binding site on HSA, and Zn2+ and Cd2+ share a different common primary binding site from them, but there is a common multi-metal binding site for all of those four metal ions. This method show advantages of fast sampling, easily to be operated and especially to be useful when ideal spectroscopic probes are not available for the study of interaction between protein and metal ions.     

Synthesis of Two Nucleotide Derivatives with Phosphate Replaced by Vanadate

SincevanadaewasfOundtobeaneboiveitheitorOfN4KATboeinl977,numerousrePOTtsonitsdiversebiolOgitaleffecshavebenPubishedandattTactedmorechendststostUdytherelevantmecbosm.IthasbeenfoundthatmostOftheseeffndareoriginatedfromtheanalogyofvanadatewithphorphae.Forthesamereason,thevanadaetBndstoactivateaseriesofenZymes.butinhibittheothers[1].ManstUdiesfocusedonthecomParativestUdiesonthevanadaeandphosphateestermCationwithcarbOhydraes,especiallythenucleosides.Theinterestinthereactionswithnucleosides…     

Interactions of Nabumetone with γ-Cyclodextrin Studied by Fluorescence Measurements

The inclusion of the anti-inflammatory drug, Nabumetone (NAB), in γ-cyclodextrin (γ-CD) was studied by fluorescence measurements. The emission fluorescence spectrum, of NAB reveals a maximum whose intensity increases with the different γ-CD’s growing concentrations. The stoichiometery (1:1) and binding constants of the complexes at 15, 25, 35, and 45 °C were extracted from the analysis of the emission spectra of NAB. The thermodynamic parameters ΔH ° and ΔS ° for the formation of the complex were calculated from the temperature dependence of the binding constants and compared with previous results for similar complexes of NAB with α- and β-CDs. The location of NAB in the complex was determined using the fluorescence quenching method. Our results indicate that NAB is completely penetrated into the cavity of γ-CD.This revised version was published online in July 2005 with a corrected issue number.     

Improvement of opipramol base solubility by complexation with β-cyclodextrin

Opipramol (OPI), a tricyclic antidepressant and anxiolytic compound, is administered orally in the form of a dihydrochloride. Salt form of the drug has a higher solubility in water and hence bioavailability and stability. A similar effect can be achieved by closing the hydrophobic part of the drug molecule in the cyclodextrin cavity. The paper presents opipramol inclusion complexes with beta-cyclodextrin (β-CD) in 1:1 molar ratio. Studies on the formation of inclusion complexes were carried out both in solution and in the solid state. The formation and physicochemical characterisation of the complexes were determined by UV spectroscopic measurement (UV–vis), Fourier Transform Infrared (FTIR) Spectroscopy, ¹H Nuclear Magnetic Resonance (¹H NMR, 2D NOESY NMR), thermoanalytical methods (TGA – Termogravimetric analysis, DSC – differential scanning calorimetry), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The phase solubility profile with β-CD was classified as the A_N- type, indicating the formation of the inclusion complex with a drug.     

Solubility enhancement of triflumizole by host-guest interaction with β-cyclodextrin

Summary The solubility enhancement of triflumizole, a systemic fungicide, by -cyclodextrin inclusion complexation was investigated by electron absorption spectroscopy. The respective association constant determined by different methods was estimated to 470±20M ^–1 in aqueous solution. A model for the host-guest complexation was deduced by molecular calculations.

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Löslichkeitsverbesserung von Triflumizole durchHost-Guest-Complexierung mit -Cyclodextrin

Zusammenfassung Die Löslichkeitsverbesserung des systemischen Fungizids Triflumizole durch Komplexierung mit -Cyclodextrin wurde mittels Elektronenabsorptionsspektroskopie untersucht. Die entsprechende Stabilitätskonstante wurde durch verschiedene Methoden erfaßt und betrug im wäßrigen Medium 470±20M ^–1. Ein Model für denHost-Guest-Complex wurde durch Molekülrechnungen erstellt.

     

Generation of hydrogen by hydroreactive compositions with γ-irradiated aluminum

The kinetics of hydrogen generation by heterogeneous hydroreactive compositions with aluminum, which was preliminarily γ-irradiated in air, held in aqueous solutions at room temperature, and annealed at a high temperature, was studied. Changes in the hydrogen generation kinetics depending on the γ-radiation dose, the composition of aqueous solution, and the temperature are caused by the conversion of aluminum oxide coatings, which should be taken into account in the prediction of the corrosion resistance of structural materials under the conditions of exposures at nuclear power plants.     

Nanofibrous mats with bird’s nest patterns by electrospinning

Electrospun material with bio-inspired ordered architectures and patterns is very interesting,yet remains a challenge.We report here that nanofibrous mats with bird’s nest patterned structures can be directly electrospun from chlorinated polypropylene solutions doped with an ionic liquid.The solution viscosity and the ionic liquid content are two dominant factors to influence the topological morphology of the nanofibrous mats.The patterned structures can be further modulated by the collection time of electrospinning,the humidity of environment and the design of collector.We suggest the electrostatic repulsion between the residual charges of the mat surface and the upcoming nanofibers plays a key role in the formation of the bird’s nest patterns.     

Preparation of PMMA Foam by Supercritical CO_2 with Ethanol

Supercritical (SC) CO2 can plasticize many amorphous polymers, which reduce the glass transition temperature of the polymers significantly. Recently, it was used as blowing agent to foam amorphous materials such as poly(methyl methacrylate) (PMMA)1,2, polystyrene (PS)3, polycarbonate (PC)4 and poly(ethylene terephthalate) (PET)4. In this foaming process, a polymer is saturated with SC CO2, and followed by rapid depressurization to atmospheric pressure. The microcellular foams can be ob…     

Preconcentration of Ultra-trace Cadmium with Nanometer-size TiO2 Colloid and Determination by GFAAS with Slurry Sampling

Cadmium-a heavy metal used in coatings, batteries and plastics-can accumulate in human’s liver and kidney, causing osteoporosis and cancer1,2. The monitoring of its content is, therefore, of great importance. But the average concentration of cadmium in w…     

A New Immunoassay Method by Capillary Electrophoresis with Enhanced Chemiluminescence Detection

Immunoassay based on capillary electrophoresis has recently been paid a great attention due to its excellent separation power, high analysis speed, small sample volume requirements, and automation 1,2. Since the injection volume is too small, immunoassay by CE needs an extremely sensitive detector. Laser-induced fluorescence3 and electro-chemical detections 4 have been used for this purpose. In fact chemilumi- nescence (CL) is also a highly sensitive method for detection, and is widely used …     

Selective oxidation of ethylbenzene catalyzed by fluorinated metalloporphyrins with molecular oxygen

This paper reported the oxidation of ethylbenzene catalyzed by fluorinated metalloporphyrins under mild conditions without any additives.The results showed that the cobalt(Ⅱ)(5,10,15,20-tetrakis(pentafluorophenyl))porphyrin was the best catalyst among the fluorinated metalloporphyrins.The conversion of ethylbenzene reached 38.6%,the selectivity to acetophenone reached 94.0%,and the turnover number is 2719 under the optimal conditions.     

Photo-promoted carbonylation of chloroalkanes with carbon monoxide by non-precious metal catalysts

The photo-promoted carbonylation of chloroalkanes with carbon monoxide was carried out under ambient conditions with copper and cadmium salts catalysts. The results indicated that the corresponding esters were produced with three salt catalysts, i.e. CuBr2, CuCl2 and CdI2. Among these catalysts, CdI2 was the most efficient in terms of ester yield and selectivity, particularly, 60% yield and 75% selectivity in the carbonylation of chlorocyclohexane were achieved. Furthermore, the yield and selectivity of the ester can be improved greatly by adding tri-n-butylamine in the CuBr2 and CuCl2 catalyst systems. On the other hand, the carbonylation did not proceed with single CdCl2, however, the catalytic activity of CdCl2 was increased greatly with NaIá2H2O as additive. As a result, we suggest that iodide ion plays an important role in the catalyst system of the cadmium salts.     

Determination of pesticides by solid phase extraction followed by gas chromatography with nitrogen–phosphorous detection in natural water and comparison with solvent drop microextraction

The European Union specificies that drinking water can contain pesticide residues at concentrations of up to 0.1 μg/L each and 0.5 μg/L in total, and that 1–3 μg/L of pesticides can be present in surface water, but the general idea is to keep discharges, emissions and losses of priority hazardous substances close to zero for synthetic substances. Therefore, in order to monitor pesticide levels in water, analytical methods with low quantification limits are required. The method proposed here is based on solid phase extraction (SPE) followed by gas chromatography with a nitrogen–phosphorous detector (GC-NPD). During method development, six organophosphate pesticides (azinphos-ethyl, chlorfenvinphos, chlorpyriphos, ethoprophos, fenamiphos and malathion) and two organonitrogen pesticides (alachlor and deltamethrin) were considered as target analytes. Elution conditions that could influence the efficiency of the SPE were studied. The optimized methodology exhibited good linearity, with determination coefficients of better than 0.996. The analytical recovery for the target analytes ranged from 70 to 100%, while the within-day precision was 4.0–11.5 %. The data also showed that the nature of the aqueous matrice (ultrapure, surface or drinking water) had no significant effect on the recovery. The quantification limits for the analytes were found to be 0.01–0.13 μg/L (except for deltamethrin, which was 1.0 μg/L). The present methodology is easy, rapid and gives better sensitivity than solvent drop microextraction for the determination of organonitrogen and organophosphate pesticides in drinking water at levels associated with the legislation.