Design and synthesis of novel α-substituted phosphonic acids catalyzed by nano zinc oxide

A series of α-substituted phosphonic acids were synthesized by a reaction between dimedone, aromatic aldehydes, and triethylphosphite in ethanolic solution under reflux conditions and using nano zinc oxide as a catalyst. Their structures were determined by Infrared, carbon, hydrogen, nitrogen, and sulfur analysis, ¹H-NMR, ¹³C-NMR, and ³¹P-NMR.     

Preparation of aluminum-doped zinc oxide (AZO) nano particles by hydrothermal synthesis

Aluminum doped zinc oxide (AZO) nanometric particles were synthesized by hydrothermal method. Aluminum nitrate hydrate, aluminum sec-butoxide and zinc nitrate hydrate were used as the starting materials, and n-propanol and 2-butanol were used as solvents. Ratio of Al₂O₃ in ZnO was kept at 10 wt%. Reaction was conducted in a Teflon autoclave at 175–225 °C for 5 h. Ratios of alcohol, H₂O and HCl to zinc nitrate hydrate were altered and 6 different sets of parameters were investigated. Obtained products were subjected to powder-XRD, particle size measurement, TEM examination and AAS analysis. Single phase AZO particles were obtained at alcohol to zinc nitrate ratio of 35, acid to zinc nitrate ratio of 0.2, at 225 °C. Particle size was determined as 3.2 ± 0.4 nm from TEM examinations and as 1–2 nm from dynamic light scattering. Synthesized particles have amphiphilic character, thus they can be dispersed in both polar and non-polar media. It was seen from the UV-diffuse reflectance spectra that the AZO powder had low reflectance in the UV region and high reflectance in the visible region. The obtained powder has the potential to be utilized in the form of thin films for optical and electronic purposes.     

Synthesis,characterization and application of zinc oxide nano particles for removal of hexavalent chromium

The present study was conducted to evaluate the adsorption efficiency of synthesized nano zinc oxide (n-ZnO) for the removal of hexavalent chromium (Cr⁶⁺). The synthesized sample was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Batch experiment results revealed that low dose (4 g L^?1) of n-ZnO was highly efficient at the initial metal concentration of 9 mg L^?1 in acidic conditions (pH 2) at 50 °C for the contact time of 90 min. A Langmuir adsorption isotherm model was found to be best fitted indicating a homogeneous surface and the adsorption followed pseudo-second order kinetics. Intra-particle diffusion was not a rate limiting factor in the present study. Thermodynamic study revealed that the adsorption process was endothermic and spontaneous at all the studied temperatures with increasing randomness.     

Complex polyion-surfactant ion salts in equilibrium with water: changing aggregate shape and size by adding oil

The phase behavior of ternary mixtures containing an alkyltrimethylammonium polyacrylate complex salt, water, and a nonpolar "oil" (n-decanol, p-xylene or cyclohexane) is investigated. The complex salts were prepared with short or long polyacrylates (30 or 6000 repeating units) and with hexadecyltrimethylammonium or dodecyltrimethylammonium surfactant ions. Phase diagrams and structures were determined by visual inspection and small-angle X-ray scattering analyses. Systems containing decanol display a predominance of lamellar phases, while hexagonal phases prevail in systems containing p-xylene or cyclohexane. The difference is interpreted as a result of the different locations of the oils within the surfactant aggregates. Decanol is incorporated at the aggregate interface, leading to a decrease in its curvature, which favors the appearance of lamellar structures. p-Xylene and cyclohexane, on the other hand, are mostly incorporated in the interior of the cylindrical aggregate, as reflected by its swelling as the oil content increases. The comparison of these results with those reported for similar systems with monovalent (bromide) counterions indicates a much more limited swelling of the lamellar phases with polymeric counterions by water. This limited swelling behavior is predominantly ascribed to bridging due to the polyions.     

Assessment of corrosion protection and performance of bio-based polyurethane acrylate incorporated with nano zinc oxide coating

In this study, a series of UV-curable anticorrosive PUA coatings embedded with varying concentrations of inorganic ZnO fillers have been successfully prepared from jatropha-based polyol. The electrochemical impedance spectroscopy (EIS) and Tafel polarisation analysis revealed that increasing fillers composition lead to the improvement of the anticorrosive property of the hybrid coatings. Meanwhile, the salt spray test results were found to correlate with the EIS of C_c (F cm⁻²) was 2.71 × 10⁻⁹, Bode plot - 10⁶ Ω cm² and Tafel polarisation results 7.56 × 10⁻⁶ MPY at 3 wt% of ZnO. Physical properties of 3 wt% loading of ZnO fillers in hardness test obtained 6H which was strongly attributed to the low interfacial interaction and poor dispersion of the fillers within the polymer matrix.     

Precursor ion scanning for the non-targeted detection of individual arsenosugars in extracts of marine organisms

Arsenosugars are a group of arsenic compounds reported to be present in a wide variety of marine organisms. Numerous such compounds have been identified and characterized in marine organisms; however, unknown arsenosugar species may also be present. This indicates the need for an analytical technique suitable for their non-targeted detection. One such technique is tandem mass spectrometry operated in the precursor ion scanning mode. This technique is based on scanning for precursor ions that give specific product ions, characteristic of the compounds under investigation. In the present study two subgroups of arsenosugar species were examined, the oxo- and the thioarsenosugars, the CID behavior of which is well known from previous studies. In the case of the oxoarsenosugars characteristic product ions were observed at m/z 237 and 97, and for the thioarsenosugars at m/z 253 and 97. Validation of this approach was carried out by analyzing extracts of two commercial kelp powders with known contents of arsenosugar species. All arsenosugars reported to exist in these materials were detected successfully using the precursor ion scanning approach. The limits of detection for the oxo- and the thioarsenosugar species, and the selectivity and sensitivity of the method, strongly indicate the suitability of this approach for the non-targeted detection of arsenosugars in extracts of marine origin.     

Synthesis of nano/micro zinc oxide rods and arrays by thermal evaporation approach on cylindrical shape substrate

Nano and micro ZnO rods and arrays have been synthesized by a simple thermal evaporation approach on a cylindrical shape substrate. Most of the synthesized ZnO products are single crystalline with a hexagonal structure and grow along the [0001] direction. Individual protrusive ZnO rods and well-aligned arrays are two typical products in our work. The individual protrusive ZnO rods have diameters of 25 nm approximately 2.1 microm and lengths from several hundred nanometers to 40 microm, while in the well-aligned arrays, the diameter and length of each ZnO rod range from 60 nm to 1.2 microm and from 4 microm to 6 microm, respectively. The heating temperature and deposition position are two key points to control the diameters of the rods. The growth mechanism is discussed and proposed. The perfect crystalline ZnO rods with different scales from nanometer to micrometer are good models for the investigation of the size effect of physical and chemical properties of one-dimensional material.     

Small-size ZnO/MgO quantum systems with zinc oxide nanoparticles of controlled size

A method is proposed for the preparation of nanosized ZnO/MgO systems by the deposition of previously formed zinc oxide nanoparticles onto a support from a colloidal solution and for determination of the size of the deposited ZnO particles from the electronic spectra. The morphology of composites containing zinc oxide nanoparticles was investigated by electronic spectroscopy and transmission electron microscopy. The possibility of synthesizing solid-phase ZnO/MgO quantum systems with controllable size characteristics was demonstrated. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 3, pp. 183–188, May–June, 2007.     

The solubility of zinc dodecanoate in xylene and tetrachloromethane

Whereas zinc dodecanoate in xylene exhibits a critical solution temperature, it does not do so in tetrachloromethane.Evidence is presented which suggests that the abrupt increase in solubility in xylene is not due to a phase change of the solid zinc dodecanoate.     

Electrochemical sensing of DNA immobilization and hybridization based on carbon nanotubes/nano zinc oxide/chitosan composite film

A novel electrochemical DNA biosensor based on zinc oxide （ZnO） nanoparticles and multi-walled carbon nanotubes （MWNTs） for DNA immobilization and enhanced hybridization detection is presented. The MWNTs/nano ZnO/chitosan composite film modified glassy carbon electrode （MWNTs/ZnO/CHIT/GCE） was fabricated and DNA probes were immobilized on the electrode surface. The hybridization events were monitored by differential pulse voltammetry （DPV） using methylene blue （MB） as an indicator. The sensor can effectively discriminate different DNA sequences related to PAT gene in the transgenic corn, with a detection limit of 2.8× 10^-12 mol/L of target sequence.     

取代芳烃对五种生物急性毒性的QSAR研究

提出成键原子的生物活性点价(Ai),并建构蕴含有机物的生物活性的自相关拓扑指数(m^Q)。使用1^Q,距离指数(L)分别与16～30种取代芳烃(含F,Cl,Br,I,NO2,OH,NH2,甲氧基,甲醛基,甲酰胺基,乙酮基,烷基等)对绿藻,斜生栅列藻,日本长腿蛙蝌蚪,发光菌,呆鲦鱼等的毒性数据关联,相应二元相关系数依次为0.9361,0.9559,0.9733,0.9354,0.9599。以上QSAR模型的估算结果均于优于相应的文献成果。     

Some biological factors related to the 137Cs concentration of marine organisms

Marine Ecology Research Institute has been studying the factors controlling the concentration of radionuclides in marine biota. Weight of fish seemed to be an important factor controlling the concentration of ¹³⁷Cs because of the good correlation observed between the weight and the concentration of ¹³⁷Cs. Food habits also seemed to be an important factor because fishes in higher trophic levels tended to indicate higher concentration factors and a positive correlation was observed between the concentrations of predator fishes and those of the foodstuff. Gender could be another factor controlling the concentration of ¹³⁷Cs because the difference of ¹³⁷Cs between gender was observed in rockfish and marbled sole.     

Combined solubility of copper and zinc oxides in ammonia-ammonium solutions

The combined solubility of copper and zinc oxides was studied in ammonia-ammonium chloride solutions with mass fractions of ammonia of 2, 5, 10, 15, 20, and 25% and mass concentrations of ammonium chloride of 43.8, 110, 150, and 180 g/l (based on chloride ion) at 293.15, 303.15, 313.15, and 323.15 K. A eutonic type equilibrium was established in the systems, and the complex ions were mutually salted out.     

Lack of nano size effect on electrochemistry of dopamine at a gold nanoparticle modified indium tin oxide electrode

Nanometer sized materials have been shown to possess excellent chemical and electrochemical catalytic properties. In this work, a gold nanoparticle (AuNP) modified indium tin oxide (ITO) electrode was employed for investigating its electro-catalytic property. AuNP was deposited on the 3-aminopropyltriethoxysilane (APTES) modified ITO electrode by self-assembly, and was characterized by scanning electron microscopy and cyclic voltammetry. Although the electrochemical reaction of dopamine was very sluggish on the ITO/APTES electrode, it was significantly enhanced after AuNP deposition. The cyclic voltammogram exhibited apparent dependence on the surface coverage of 11 nm AuNPs, which could be rationalized by different modes of mass diffusion. Among the different sizes of AuNP investigated, the lowest anodic peak potential was observed on 11 nm AuNP. However, the potential was still about 50 mV more positive than that obtained on a bulk gold electrode of similar geometry. It is therefore concluded that there is no nanometer size effect of AuNP modified ITO on the electrochemistry of dopamine.     

The active site of a zinc-dependent metalloproteinase influences the computed pK(a) of ligands coordinated to the catalytic zinc ion

TNF-alpha converting enzyme (TACE) is a multidomain, membrane-anchored protein that includes a Zn-dependent protease domain. It releases the soluble form of cytokine tumor necrosis factor-alpha (TNF-alpha) from its membrane-bound precursor. TACE is a metalloprotease containing a catalytic glutamic acid, Glu-406, and a Zn(2+) ion ligated to three imidazoles. The protonation states of the active site glutamic acid and inhibitors are important factors in understanding the potency of inhibitors with acidic zinc-ligating groups such as hydroxamic and carboxylic acids. Density functional methods were utilized to compute pK(a) values using a model of the catalytic site of TACE and to predict a concomitant mechanism of binding, consistent with lowering the pK(a) of the bound ligand and raising the pK(a) of the active site Glu-406. Weak acids, such as hydroxamic acids, bind in their neutral form and then transfer an acidic proton to Glu-406. Stronger acids, such as carboxylic acids, bind in their anionic form and require preprotonation of Glu-406. Similar binding events would be expected for other zinc-dependent proteases.     

Microwave synthesis of zinc sulfite and porous zinc oxide microrods

ZnSO(3) microrods with uniform size and shape can be prepared under microwave irradiation at much higher speed than a conventional heating bath, usually in minutes. The annealing of ZnSO(3) microrods produced porous ZnO microrods with pore size between 50-200 nm.     

Distribution of inorganic arsenic and methylated arsenic in marine organisms

Inorganic arsenic and methylated arsenic compounds in 60 specimens of marine organisms were investigated by hydride generation derivatization and cold-trap gas chromatography–mass spectrometry (GC MS). Chloroform–methanol extracts from seaweeds, shellfish, fish, crustaceans and other marine organisms were separated into water-soluble and lipid-soluble fractions. The arsenic compounds in each fraction were identified and analysed as arsine, methylarsine, dimethylarsine and trimethylarsine. Trimethylarsenic compounds were distributed mainly in the water-soluble fraction of muscle of carnivorous gastropods, crustaceans and fish. The amounts of dimethylated arsenic compounds were found to be larger than that of trimethylated arsenic in the lipid-soluble fraction of fish viscera. Dimethylated arsenic compounds were distributed in the water-soluble fraction of Phaeophyceae.     

Arsenic speciation in marine organisms: from the analytical methodology to the constitution of reference materials

An analytical procedure for total arsenic and arsenic species quantification in marine organisms has been developed. Fresh materials are freeze-dried and reduced to powders before analysis. Arsenic is determined either by energy dispersive X-ray fluorescence (EDXRF) directly or by inductively coupled plasma optical emission spectrometry (ICP/OES) after microwave digestion. Arsenic speciation is performed on the extracted sample using liquid chromatography coupled to ICP/OES for arsenobetaine and arsenocholine determination and to the hydride generation-quartz furnace atomic absorption spectrometric technique for arsenite, arsenate, monomethylarsonic and dimethylarsinic acids quantification. Special precautions are taken to avoid losses or contaminations as well as to prevent analytical errors during the quantification stage. Other methods are applied and the corresponding results compared for each step of the procedure. The method is finally validated by means of intercomparison studies within the Measurements and Testing Programme of the European Community (formely BCR).