G-quadruplex-based DNAzyme for sensitive mercury detection with the naked eye

Hg2+ is able to inhibit the peroxidase-like DNAzyme function of a T-containing G-quadruplex DNA via Hg2+-mediated T-T base pairs, which enables the visual detection of Hg2+ in the TMB-H2O2 reaction system with high selectivity and sensitivity.

Hydrothermal Synthesis and Luminescent Properties of Novel Ordered Sphere CePO4 Hierarchical Architectures

The ordered-sphere CePO4 hierarchical architectures have been successfully synthesized by a simple hydrothermal method through the controlled growth of the CePO4 nanorods and self-assemble hierarchical structure under various reaction conditions. The evolution of the morphology of the samples has been investigated in detail. It was found that the coexistence of citric acid and cetaltrimethylammonium bromide in the reaction system plays an important role in the formation of the spherical CePO4 hierarchical architectures. A possible mechanism of the formation and growth of the hierarchical structure was suggested according to the experimental results and analysis. The effects of the reaction time as well as the variation of the morphologies on the luminescent properties of the products were also studied.

Highly uniform and monodisperse beta-NaYF4 : Ln(3+) (Ln = Eu, Tb, Yb/Er, and Yb/Tm) hexagonal microprism crystals: Hydrothermal synthesis and luminescent properties

beta-NaYF4:Ln(3+) (Ln = Eu, Tb, Yb/Er, and Yb/Tm) hexagonal microprisms with remarkably uniform morphology and size have been synthesized via a facile hydrothermal route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra as well as kinetic decays were used to characterize the samples. It is found that sodium citrate as a shape modifier introduced into the reaction system plays a critical role in the shape evolution of the final products. Furthermore, the shape and size of the products can be further manipulated by adjusting the molar ratio of citrate/RE3+ (RE represents the total amount of Y3+ and the doped rare earth elements such as Eu3+, Tb3+, Yb3+/Er3+, or Yb3+/Tm3+). Under the excitation of 397 nm ultraviolet light, NaYF4:xEu(3+) (x = 1.5, 5%) shows the emission lines of Eu3+ corresponding to D-5(0-3) -> F-7(J) (J = 0-4) transitions from 400 to 700 nm (whole visible spectral region) with different intensity, resulting in yellow and red down-conversion (DC) light emissions, respectively.

Synthesis of neodymium hydroxide nanotubes and nanorods by soft chemical process

A facile soft chemical approach using cetyltrimethylammoniurn bromide (CTAB) as template is successfully designed for synthesis of neodymium hydroxide nanotubes. These nanotubes have an average outer diameter around 20 nm, inner diameter around 2 nm, and length ranging from 100 to 120 nm, high BET surface area of 495.71 m(2) g(-1). We also find that neodymium hydroxide nanorods would be obtained when CTAB absented in reaction system. The Nd(OH)(3) nanorods might act as precursors that are converted into Nd2O3 nanorods through dehydration at 550 degrees C. The nanorods could exhibit upconversion emission characteristic under excitation of 591 nm at room temperature.

Site substitution and energy transfer of Eu2+ and Ce3+ in KMgF3 : Eu and KMgF3 : Eu-Ce single crystals

The high-resolution emission spectra of KMgF3 : Eu and KMgF3 : Eu-Ce single crystals were measured at 77 K. The site substitution of Eu2+ and Eu2+-Ce3+ co-doped system in KMgF3 was discussed. Eu2+ substituted for K+ sites on three different site-symmetry: cubic, trigonal and tetragonal. The attribution of all lines occurring in the emission spectra were ascertained. The indirect energy transfer from P-6(5/2) states of Eu2+ to 4f5d states of Ce3+ in KMgF3 : Eu-Ce was observed and the energy transfer mechanism was studied. The d-d interaction among levels was proposed.

Study on the synthesis of mixed oxide La2CuO4 and the effect on the catalytic activity to catalytic removal of NO

The mixed oxide La2CuO4 was synthesized by four different methods and characterized with XRD, BET, TEM and low angle XRD. The effect of the synthetic method on the crystal structure, crystal size, surface area and catalytic activity to NO - CO reaction were studied. The results showed that the samples derived from different methods exhibited different activity to NO-CO reaction, the reason may be that the concentration and type of oxygen defect were different when the synthetic methods were different.

A study of catalysis of copper-aluminium hydrotalcite-like compounds in the phenol hydroxylation

Copper-Aluminium Hydrotalcite-like compounds are synthesized by coprecipitation and characterized with XRD and IR. Catalysis of the above mentioned HTLcs are investigated in the phenol hydroxylation, good results are obtained. Meanwhile, the effects of the ratio of Cu/Al, reaction temperature, reaction medium and pH of reaction system are discussed, The reaction mechanism is also proposed.

Cure processing modeling and cure cycle simulation of epoxy-terminated poly(phenylene ether ketone) .4. Cure cycle simulation

Epoxy-terminated poly(phenylene ether ketone) (E-PEK) developed in this Institute is a candidate matrix resin for polymer composites as structural materials. Cure cycles for this reaction system were simulated according to the previously established processing model. It is found that for the E-PEK system, the curing process is best completed by a stepwise cure cycle comprising two isothermal processes at different temperatures, T-1 and T-2. The cure cycles over a wide range of processing parameters simulated, based on the established processing model, indicate that the processing window is width-adjustable. Analysis of the mechanical properties of the composite sheets showed that the simulated cure cycles are acceptable and reliable. (C) 1997 John Wiley & Sons, Inc.

THE CATALYTIC ACTIVITY OF HETEROPOLY ACIDS (SALTS) AND MONO-LACUNARY HETEROPOLY TUNGSTOPHOSPHORIC COMPOUND IN THE OXIDATION OF ALCOHOLS

The catalytic activity of heteropoly compounds in the oxidation of benzyl alcohol and cyclohexa nol under phase transfer conditions has been studied. The catalytic activity of six kinds of heteropoly acids with Keggin structure will drop by the order of GeMo12 (H4GeMo12O40). PW12, PMo12, SiMo12, GeW12 and SiW12. When the three protons of H3PW12O40 Were replaced by Na+ step by step, the catalytic activity will raise gradually with the drop of acidity. The addition of base and trace amount of sulfuric acid to the reaction system resulted in an increase of catalytic activity. It was found that catalytic activity of mono-lacunary heteropoly compounds is higher than that of the primary heteropoly acids (or salts). The catalytic oxidation system of HPA-H2O2-PTC is very active in the oxidation of benzyl alcohol ana cyclohexanol, but it has little activity in the oxidation of inactive compounds such as n(or iso)-proplalcohol. n-butyl alcohol and n-hexanol. Solvent has great effect on reaction, when polar compounds such as water were used as solvent, the catalytic activity is better than that when non-polar compounds were used as solvent.

Integrated cultivation of the red alga Kappaphycus alvarezii and the pearl oyster Pinctada martensi

The effect of simultaneously cultivating the pearl oyster Pinctada martensi and the red alga Kappaphycus alvarezii on growth rates of both species was investigated in laboratory and field studies conducted from December 1993 to June 1995. The two study sites were in subtidal areas 100 km apart off the east coast of Hainan Island, China. Pearl oysters were cultivated in the center of an algal farm and red alga was cultivated in the center of the pearl oyster farm. These field experiments showed higher growth rates of both P. martensi and K. alvarezii in a co-culture system than in a monospecies culture system. Laboratory studies showed that the algae removed nitrogenous wastes released by pearl oysters. Algae treated with pearl oyster wastes grew much faster than those without oyster wastes. Algae treated with the seawater to which NH4Cl, NaNO3 and NaNO2 were added grew at the same rate as those treated with natural seawater containing oyster nitrogenous wastes, suggesting that enhanced growth of algae in the co-culture system was largely due to nitrogenous metabolites of the pearl oysters. In the co-culture, growth of pearl oysters was positively influenced by the presence of rapidly growing algae but when seawater temperature decreased below 20 degrees C, the algae grew slowly and there was no measurable benefit of mixed culture to either algae or pearl oyster.

胶东地区三类金矿成矿系统地质地球化学及动力学

The East Shandong gold province is located on the southeastern margin of the North China Craton and features uplift in the north and depression in the south. The uplift area is made up of the Archaean Jiaodong Group, the Proterozoic Jingshan Group and Yanshannian granites. Most gold deposits in the uplift area are spatially associated with the Yanshannian granites. Two types of gold mineralization occur in the region: the quartz-vein type hosted in the Linglong granite suite, and the shear zone type hosted by either the Linglong granite or Guojialing granitoid suites. The mineralization ages are 113～126 Ma. The southern part of East Shandong contains the Mesozoic Jiaolai basin, which formed during regional extension. The basin is bounded by the Wulian-Rongcheng fault in the southeast and the Tanlu fault in the west. The Pengjiakuang, Fayunkuang and Dazhuangzi gold deposit occurs on the northeastern margin of the basin. The mineralization ages of these deposits are 110～128 Ma. This paper focuses on a low-angle detachment fault developed between the Proterozoic Jingshan Group metamorphic complex and the northeastern margin of the basin. Our field work shows that the distribution of the Pengjiakuang gold deposit was controlled by the detachment fault. Moreover, the Fayunkuang, Guocheng and Liaoshang gold deposits also occurr in the periphery of the basin, and their features are similar to Pengjiakuang gold deposit. The study of geological geochemistry of the gold deposits has shown: ①three-type gold deposit was situated in the Jiaodong area, including altered rock type (Jiaojia type), quartz vein type (Linglong type) and breccia type (Pengjiakuang type); the ore-forming materials and fluid for Pengjiakuang type gold deposit shows multiple source; ②the ore materials of Jiaojia and Linglong type deposits are mainly from deep source. The author has studied geological-geochemical dynamics of three types deposits in Jiaodong area. The study of tectonic dynamics shows that ore-forming structure differential stress values of Pengjiakuang gold deposit is 100 * 10~6～130 * 10~6 Pa, and that of Jiaojia gold deposit is 100 * 10~5～194 * 10~6 Pa. Dynamics of hydrothermal ore-forming fluid has also been studied in this paper. Author applies Bernoulli equation to dynamic model of hydrothermal fluid motion in brittle fracture and cracks (quartz vein type gold mineralization), and applies Darcy law to dynamic model of hydro thermal fluid motion in porous medium (altered rock type gold mineralization). Author does daring try in order to study quantitativly transport mechanism of hydrothermal ore-forming fluid in this paper. The study of fluid inclusions and crystal dynamics shows that reaction system of hydrothermal ore-forming includes three types, as follows: ore-forming reaction, controlling reaction and buffer controlling reaction. They depend on each other, controlling each other, which form a organic system. Further research shown that formation of ore shoots was controlled by coincidence processes of tectonic dynamic condition and thermodynamic evolution. This paper has summaried reginoal metallogenic laws and seted up metallogenic(dynamics) models for Jiaodong gold ore belt.

Continuous configuration time-dependent self-consistent field method for polyatomic quantum dynamical problems

A new continuous configuration time-dependent self-consistent field method has been developed to study polyatomic dynamical problems by using the discrete variable representation for the reaction system, and applied to a reaction system coupled to a bath. The method is very efficient because the equations involved are as simple as those in the traditional single configuration approach, and can account for the correlations between the reaction system and bath modes rather well. (C) American Institute of Physics.

Modelling the fluid dynamics and coupled phenomena in arc weld pools

A 3D model of melt pool created by a moving arc type heat sources has been developed. The model solves the equations of turbulent fluid flow, heat transfer and electromagnetic field to demonstrate the flow behaviour phase-change in the pool. The coupled effects of buoyancy, capillary (Marangoni) and electromagnetic (Lorentz) forces are included within an unstructured finite volume mesh environment. The movement of the welding arc along the workpiece is accomplished via a moving co-ordinator system. Additionally a method enabling movement of the weld pool surface by fluid convection is presented whereby the mesh in the liquid region is allowed to move through a free surface. The surface grid lines move to restore equilibrium at the end of each computational time step and interior grid points then adjust following the solution of a Laplace equation.

Deactivation of Oxidation Catalysts by Oil-Derived Sulphur

The most common mode of deactivation suffered by catalysts fitted to two-stroke engines has traditionally been thermal degradation, or even meltdown, of the washcoat and substrate. The high temperatures experienced by these catalysts are caused by excessively high concentrations of HC and CO in the exhaust gas which are, in turn, caused by a rich AFR and the loss of neat fuel to the exhaust during the scavenging period. The effects of catalyst poisoning due to additives in the oil is often regarded as a secondary, or even negligible, deactivating mechanism in two-stroke catalysts and has therefore received little attention. However, with the introduction of direct in-cylinder fuel injection to some larger versions of this engine, the quantities of HC escaping to the exhaust can be reduced to levels similar to those found on four-stroke gasoline engines. Under these conditions, the effects of poisoning are much more significant to catalyst durability, particularly for crankcase scavenged derivatives which allow considerable quantities of oil to escape into the exhaust in a neat, or partially burned form. In this paper the effects of oil-derived sulphur on catalyst performance are examined using specialised test apparatus. The oil used throughout the study was formulated specifically for a two-stroke engine fitted with direct in-cylinder fuel injection. The sulphur content of this oil was 0.21% by mass and particular attention was paid to the role of this element in the resulting deactivation. The catalyst was also designed for two-stroke applications and contained a high palladium loading of 300g/ft3 (28g/l) to prolong the life of the catalyst. It was found that the sulphur caused permanent deactivation of the CO reaction and increased the light-off temperature by around 40oC after oiling for 60 hours. This deactivation was progressive and led to a reduction in surface area of the washcoat, particularly in the micropores of around 5Å diameter. By using a validated catalyst model the change in surface area of the precious metal was estimated. It was found that the simulated palladium surface area had to be reduced by a factor of around 7.5 to produce the light-off temperature of the deactivated catalyst. Conversely, the light-off temperature of the C3H6 reaction was barely affected by the deactivation.

Development and clinical validation of a loop-mediated isothermal amplification (LAMP) method for the rapid detection of Neisseria meningitidis

Loop-mediated isothermal amplification (LAMP) is an innovative technique that allows the rapid detection of target nucleic acid sequences under isothermal conditions without the need for complex instrumentation. The development, optimization, and clinical validation of a LAMP assay targeting the ctrA gene for the rapid detection of capsular Neisseria meningitidis were described. Highly specific detection of capsular N. meningitidis type strains and clinical isolates was demonstrated, with no cross-reactivity with other Neisseria spp. or with a comprehensive panel of other common human pathogens. The lower limit of detection was 6 ctrA gene copies detectable in 48 min, with positive reactions readily identifiable visually via a simple color change. Higher copy numbers could be detected in as little as 16 min. When applied to a total of 394 clinical specimens, the LAMP assay in comparison to a conventional TaqMan® based real-time polymerase chain reaction system demonstrated a sensitivity of 100% and a specificity of 98.9% with a ? coefficient of 0.942. The LAMP method represents a rapid, sensitive, and highly specific technique for the detection of N. meningitidis and has the potential to be used as a point-of-care molecular test and in resource-poor settings.