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

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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.     

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…     

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.     

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…     

All-small-molecule dynamic covalent gels with antibacterial activity by boronate-tannic acid gelation

Reversible boronate-catechol linkage was widely used to construct two-dimensional coatings and threedimensional nanostructures or hydrogels.The construction of these functional materials usually requires the pre-synthesis of macro molecular building blocks,and direct gelation between natural polyphenols and small molecule boranic acids is yet to be investigated.In this study,we fabricated a family of allsmall-molecule dynamic covalent gels consisting of tannic acid and boronic acids.Transparent and thixotropic gels were formed by boronate affinity towards catechol groups abundant on natural polyphenols.The gels showed multi-responsiveness,such as acid-,base-,reduction-and oxidantsensitive depending on the used boronic acid building blocks.The chemistry for gel formation and stimuli-responsiveness was characterized by11B NMR spectroscopy.The multi-stimuli responsiveness,green processing and facile modular design make the boronic acid-tannic acid gels promising candidates for the development of smart soft materials.     

Oxidation of Alcohols Catalyzed by Ruthenium Complexes with Iodosylbenzene as Oxidant

Five ruthenium complexes such as Phen-Ru-Phen, Phen-Ru-Bipy, Phen-Ru-Quin, Quin-Ru-Quin and Bipy-Ru-Quin (where Phen=l, 10-phenanthroline, Quin=8-hydroxyquinoline, Bipy=2, 2‘-bipyridine) were synthesized and used as catalysts for the oxidation of benzylic and primary aliphatic alcohols with iodosylbenzene as oxidant. The oxidations were carried out at room temperature, affording the corresponding aldehydes and ketones with high selectivity.     

Quantifying Protein–Protein Interactions by Molecular Counting with Mass Photometry

Interactions between biomolecules control the processes of life in health and their malfunction in disease, making their characterization and quantification essential. Immobilization- and label-free analytical techniques are desirable because of their simplicity and minimal invasiveness, but they struggle with quantifying tight interactions. Here, we show that mass photometry can accurately count, distinguish by molecular mass, and thereby reveal the relative abundances of different unlabelled biomolecules and their complexes in mixtures at the single-molecule level. These measurements determine binding affinities over four orders of magnitude at equilibrium for both simple and complex stoichiometries within minutes, as well as the associated kinetics. These results introduce mass photometry as a rapid, simple and label-free method for studying sub-micromolar binding affinities, with potential for extension towards a universal approach for characterizing complex biomolecular interactions.