Facile synthesis of highly uniform octahedral LuVO4 microcrystals by a facile chemical conversion method

Uniform octahedral LuVO4 microcrystals have been successfully prepared through a designed two-step hydrothermal method. One-dimensional lutetium precursor was first prepared through a simple hydrothermal route. Subsequently, a well-shaped octahedral LuVO4 sample was synthesized at the expense of the wirelike precursors during the hydrothermal process. The whole process in this method was carried out in aqueous conditions without the use of any organic solvents, surfactant, or catalyst. The conversion process from nanowire precursor to octahedral product has been investigated in detail. The LuVO4 : Ln(3+) (Ln Eu, Dy, Sm, and Er) phosphors show strong light emissions with different colors coming from different activator ions under ultraviolet light excitation or low-voltage electron beam excitation. Furthermore, this general and facile method may be of much significance in the synthesis of many other lanthanide compounds with polyhedral morphology.

Synthesis of mesoporous YF3 nanoflowers via solvent extraction route

Mesoporous YF3 nanoflowers were successfully prepared via solvent extraction route. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations indicated that these nanoflowers with uneven porous architectures had a spherical shape and were consisted of many YF3 nanosheets with a thickness of about 15 not. Energy-dispersive spectroscopy (EDS) analysis was used to check the chemical composition and purity of the products. YF3 nanoflowers had bimodal mesoporous distribution and Brunauer-Emmett-Teller (BET) surface area of 116 m(2)/g.

Templateless, surfactantless, simple electrochemical route to rapid synthesis of diameter-controlled 3D flowerlike gold microstructure with "clean" surface

We report for the first time a simple low-cost electrochemical route to synthesis of diameter-controlled hierarchical flowerlike gold microstructures with "clean'' surfaces using gold nanoplates or nanopricks as building blocks without introducing any template or surfactant.

A general route to transform normal hydrophilic cloths into superhydrophobic surfaces

Herein, we describe a simple and inexpensive method for forming superhydrophobic cloths with the highest water contact angle of close to 180 degrees, in which normal commercial cloths serving as pristine materials are modified with suitable gold micro/nanostructures.

Large scale, templateless, surfactantless route to rapid synthesis of uniform poly(o-phenylenediamine) nanobelts

We reported the interesting finding that large scale uniform poly(o-phenylenediamine) nanobelts with several hundred micrometers in length, several hundred nanometers in width, and several ten nanometers in height can be rapidly yielded from an o-phenylenediamine-HAuCl4 aqueous solution without the additional introduction of other templates or surfactants at room temperature.

A novel route to polyethylene-polystyrene blends through the fragmentation of porous polystyrene beads supported metallocene in ethylene polymerization

Polyethylene-polystyrene blends were synthesized by in situ ethylene polymerization with polystyrene porous beads supported metallocene; the influence of fragmenting support beads on the morphology and the mechanical performance of the blends was investigated.

Synthesis and characterization of ultrafine CeF3 nanoparticles modified by catanionic surfactant via a reverse micelles route

In this article, we firstly reported on the synthesis and characterization of ultratine CeF3 nanoparticles (NPs) modified by catanionic surfactant via a reverse micelles-based route. The catanionic surfactant PN was prepared by mixing the di(2-ethylhexyl) phosphoric acid (DEHPA) and primary amine (N1923) with 1:1 molar ratio. It exhibited a high surface activity and formed much small reverse micelles in comparison with its individual component (DEHPA or N1923). The PN reverse micelles were then used as templates to prepare ultrafine CeF3 NPs. The narrow distributed nanoparticles have an average diameter 1.8 nm. FTIR spectra indicated that there existed strong chemical interactions between nanoparticles and the adsorbed surfactants. The modification resulted in the FFIR peak position of P=O shifting to lower energy. Due to the effect of modification and small size, the CeF3 NPs showed a remarkable red shift of 54 mn in the fluorescence emission in comparison with that of bulk material and a red shift of 18 nm in contrast with that of the normal CeF3 NPs with an average diameter of 16 nm.

Reactions of C-60 with R(3)SnH: A new synthetic route to C-60(RH)(n) and the property of C-60 to catalyze radical reactions

A new method for the preparation of polyalkyl and polyarenefullerene derivatives C-60(RH)(n)(R=Bu,n=1-3; R=Ph,n=1-10) by the reaction of C-60 with organotin hydride in toluene is described. Another series of products of stannanes R(a)Sn(b)H(c) (R=Bu, a=3-8, b=1-4, c=0-3 R=Ph, a=3-11, b=1-5, c=0-4) were also obtained, which shows that C-60 can catalyze polymerization of organic-tin. These products were determined by mass and infrared spectrometry. And the possible reaction mechanisms are discussed.

Temperature measurement of reflected shock wave by using chemical indicator

This report describes a new method for measuring the temperature of the gas behind the reflected shock wave in shock tube, corresponding to the reservoir temperature of a shock tunnel, based on the chemical reaction of small amount of CF4 premixed in the test gas. The final product C2F4 is used as the temperature indicator, which is sampled and detected by a gas chromatography in the experiment. The detected concentration of C2F4 is correlated to the temperature of the reflected shock wave with the initial pressure P-1 and test time tau as parameters in the temperature range 3 300 K < T < 5 600 K, pressure range 5 kPa < P1 <12 kPa and tau similar or equal to 0.4 ms.

Mechano-Chemical Coupling at Molecular Level: Forced Dissociation of Selectin/Ligand Binding

Mechano-chemical coupling is a common phenomenon that exists in various biological processes at different physiological levels. Bone tissue remodeling strongly depends on the local mechanical load. Leukocytes are sheared to form the transient aggregates with platelets or other leukocytes in the circulation. Flow pattern affects the signal transduction pathways in endothelial cells. Receptor/ligand interactions are important to cell adhesion since they supply the physical linkages...

Modified Simplified Rate Equation Model of Flowing Chemical Oxygen-Iodine Laser and its Application

A modified simplified rate equation (RE) model of flowing chemical oxygen-iodine laser (COIL), which is adapted to both the condition of homogeneous broadening and inhomogeneous broadening being of importance and the condition of inhomogeneous broadening being predominant, is presented for performance analyses of a COIL. By using the Voigt profile function and the gain-equal-loss approximation, a gain expression has been deduced from the rate equations of upper and lower level laser species. This gain expression is adapted to the conditions of very low gas pressure up to quite high pressure and can deal with the condition of lasing frequency being not equal to the central one of spectral profile. The expressions of output power and extraction efficiency in a flowing COIL can be obtained by solving the coupling equations of the deduced gain expression and the energy equation which expresses the complete transformation of the energy stored in singlet delta state oxygen into laser energy. By using these expressions, the RotoCOIL experiment is simulated, and obtained results agree well with experiment data. Effects of various adjustable parameters on the performances of COIL are also presented.

Numerical Simulation of Gaseous Detonation of H_2-O_2 Mixture with Detailed Chemical Reaction Model

采用高精度的ENO格式和基于基元化学反应的真实化学反应模型求解氢氧混合气体一维爆轰波的精细结构。采用直接起爆方法得到稳定传播的爆轰波,计算的爆轰波阵面参数和实验相当符合。对爆轰波反应区化学反应的研究表明,参与反应的不同组分具有不同类型的变化特征。网格尺寸影响的研究表明,计算结果的精度随着网格尺寸的增加而增加,并能保持较好的收敛性。移动网格研究结果表明,网格运动速度和爆轰速度接近时,两者的相互作用对计算结果产生一定影响。

Growth of bulk single crystals beta-FeSi2 by chemical vapour deposition

Bulk single crystals b-FeSi2, as a new photoelectric and thermoelectric material, has been successfully grown using chemical vapor transport technique by using iodine as transport agent in a sealed ampoule. The effects of crystal growth condition on quality and morphologies of the single crystals were studied. Both needle-like and grain-like single crystals were gained. By changing substrate temperature, tetrahedral high quality a-FeSi2 single crystals were also obtained.

Performance analyses of flowing chemical oxygen-iodine laser

A modified simplified rate-equation model that utilizes the Voigt profile function and another gain saturation model deduced from the kinetic equations are presented for performance analyses of a flowing chemical oxygen-iodine laser. Both models are adapted to both the condition of homogeneous broadening and that of inhomogeneous broadening being of importance and the condition of inhomogeneous broadening being predominant. Effects of temperature and iodine density on the output power and on variations of output power, optical intensity, and saturation intensity with flow distance are presented as well. There are differences between results of two models, but both qualitatively agree with known results.

Chemical kinetics and self-ignition in a model supersonic hydrogen-air combustor

Self-ignition tests of a model scramjet combustor were conducted by using parallel sonic injection of gaseous hydrogen from the base of a blade-like strut into a supersonic vitiated airstream. The range of stagnation pressure and temperature studied varied from 1.0 to 4.5 MPa and from 1300 to 2200 K, respectively. Experimental results show that the self-ignition limit, in terms of either global or local quantities of pressure and temperature, exhibits a nonmonotonic behavior resembling the classical homogeneous explosion limit of the hydrogen-oxygen system. Specifically, for a given temperature, increasing pressure from a low value can render a nonignitable mixture to first become ignitable, then nonignitable again, This correspondence shows that, despite the globally supersonic nonpremixed configuration studied herein, ignition is strongly influenced by the intricate chemical reaction mechanism and thereby exhibits the homogeneous explosion character. Consequently, self-ignition criteria based on a global reaction rate approximating the complex chemistry are inadequate. An auxiliary computational study on counterflow ignition was also conducted to systematically investigate the contamination effects of vitiated air. Results indicate that the net contamination effects for the present experimental data are expected to be substantially smaller than contributions from the individual contamination species because of the counterbalancing influences of the H2O-inhibition and NO-promotion reactions in effecting ignition.