The Pt-Sr(Zr1-
Tungsten carbide (WC) nanocrystals have been prepared by a solvothermal method with Mg as the reductant and WO3 and anhydrous ethanol as the precursors. The effects of time and temperature on the synthesis of WC were investigated and a probable formation mechanism was discussed. The obtained WC nanocrystals were characterized by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy and electrochemical methods. Hexagonal close-packed WC was successfully synthesized when the temperature was as low as 500°C. The content of carbon was more than that of W, indicating that the composition of the treated sample was C and WC only. The diameters of WC nanocrystals were ranged from 40 nm to 70 nm and the nanocrystals were dispersed on carbon films. The electrochemical measurements reveal that WC nanocrystals obviously promote Pt/C electrocatalytic ability for the oxygen reduction reaction.
1-Butyl-3-methylimidazolium dodecatungstophosphate catalyst ([bmim]3PW12O40) with high water tolerance was prepared from 1-butyl-3-methylimidazolium bromide ([bmim]Br) and phosphotungstic acid (H3PW12O40). The catalyst was characterized by means of Fourier transform infrared spectroscopy, thermogravimetry-differential scanning calorimetry,
The thermal decomposition kinetics of the
Using MCM-41 as the supporter, a series of MCM-41 supported amino-palladium complexes has been prepared and characterized by XRD (X-ray diffraction) and XPS (X-ray photoelectron spectroscopy), etc. The XRD and XPS results indicate that the Pd coordinates with the -NH2 groups on the MCM-41 surface, and the structure of MCM-41 has been not damaged. Its catalytic performance for Heck arylation of alkene with aryl iodide shows that the catalysts have high activity and stereoselectivity in 70-90°C. The product of Heck reaction is in
A series of luminescent hybrid materials Eu(Phen)2Cl3/MCM-41 that the different assembled mass of Eu(Phen)2Cl3 included into the channels of MCM , have been synthesized by combining ultrasound technology. The properties of the hybrid materials were characterized by XRD(X-ray Diffraction), N2-adsorption-desorption, FT-IR and luminescence spectrum. The results show that the rare-earth compounds had been loaded into the holes of mesoporous material MCM-41. The luminescence intensities of the hybrid materials were improved as the increase of the loading concentration of the rare-earth complexes. The hybrid material has the maximal luminescence intensity when it reached the saturated loading concentration (7.17%). To compare with the pure rare-earth complex, the thermal stability of the hybrid materials were enhanced by about 100°C.
Nano-sized cobalt particles with the diameter of 2 nm were prepared via an organic colloidal process with sodium formate, ethylene glycol and sodium citrate as the reducing agent, the solvent and the complexing agent, respectively. The effects of sodium citrate on the yield, crystal structure, particle size and size distribution of the prepared nano-sized cobalt particles were then investigated. The results show that the average particle diameter decreases from 200 nm to 2 nm when the molar ratio of sodium citrate to cobalt chloride changes from 0 to 6. Furthermore, sodium citrate plays a crucial role in the controlling of size distribution of the nano-sized particles. The size distribution of the particle without sodium citrate addition is in range from tens of nanometers to 300 or 400 nm, while that with sodium citrate addition is limited in the range of (2±0.25) nm. Moreover, it is found that the addition of sodium citrate as a complex agent could decrease the yield of the nano-sized cobalt particle.
The aim of this research is to study the thermodynamic behavior of resins of chitosan microspheres (RCM) in adsorbing Cu2+, so that the theoretical basis of the application of RCM to eliminate metal ions in wastewater or fruit and vegetable juice can be obtained. First, RCM were prepared from chitosan as a raw material by using reverse phase suspension cross-linking polymerization, and some physicochemical properties of RCM were characterized. Second, the adsorption behavior of Cu2+ onto RCM was investigated by the batch method. The results show that the diameter of the microspheres was relatively uniform and the surface of microspheres was compacted with pores. The physical properties of the RCM were as follows: water content 51.982%, skeletal density 1.212 g?cm-3, pileup density 0.862 g?mL-1, porosity was in 0.554 and crosslinking degree was in 13.581%. The saturated adsorption capacity of RCM for Cu2+ was 0.993 mmol?g-1. At the same time, the results also indicated that the adsorption of RCM for Cu2+ followed the Langmuir isotherm equation:
Polystyrene microspheres with an average diameter of 55 μm were prepared by suspension polymerization
Flowerlike MoS2 nanoparticles have been successfully synthesized through a mild solvothermal reaction with the aid of ethanol aqueous solution, and the samples have been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and low temperature nitrogen adsorption-desorption. The nanometer flower MoS2 is composed of ultrathin nanosheets of approximately 10 nanometers in thickness. The influence of the reaction temperature and the reaction time on the formation of the flowerlike MoS2 nanoparticles were evaluated. The optimal experimental conditions were determined as follows: the molar ratio of 1∶1 between ethanol and water, the reaction temperature of 190°C, and the reaction time of 24 h.
Symmetrical and asymmetrical triphenylene discotic liquid crystals with two kinds of different peripheral chains,
Ketol-acid reductoisomerase(KARI) is a promising target for the design of herbicides yet there are only few reports on the molecular design of KARI inhibitors. In this paper, based on the reported 0.165 nm high resolution crystal structure of the spinach KARI complex, 279 molecules with low binding energy toward KARI were obtained from an MDL/ACD 3D database search using the program DOCK 4.0. According to the structural information of 279 molecules provided, some amide compounds have been designed and synthesized. The bioassay results show that most of these amides had inhibitory activity to rice KARI at a test concentration of 200 μg/mL. Among which eight amides, compounds
In this paper, we first introduced the basic principle of fluorescence cross-correlation spectroscopy (FCCS) and then established an FCCS setup using a single wavelength laser. We systematically optimized the setup, and the detection volume reached about 0.7 fL. The home-built setup was successfully applied for the study of the binding reaction of human immunoglobulin G with goat antihuman immunoglobulin G. Using quantum dots (745 nm emission wavelength) and Rhodamine B (580 nm emission wavelength) as labeling probes and 532 nm laser beam as an excitation source, the cross-talk effect was almost completely suppressed. The molecule numbers in a highly focused volume, the concentration, and the diffusion time and hydrodynamic radii of the reaction products can be determined by FCCS system.
To overcome the peak band broadening and to increase the peak capacity and separation efficiency of a two-dimensional liquid chromatographic system, a high-temperature normal phase liquid chromatography (HTNPLC) was used as the first dimension (1st-D), and a RPLC was used as the second dimension (2nd-D). The sample was first separated on the 1st-D CN column and the primary eluent stored in the sampling-loop system alternatively (in HTNPLC×RPLC mode) or selectively (in HTNPLC/RPLC mode) and was then transferred to 2nd-D C18 column for further separation. The resolution and separation efficiency of the systems were greatly improved. The systems were evaluated by analyzing several polycyclic aromatic hydrocarbons and
To explore the protein-level mechanism of action verapamil in acute myocardial infarcted rats, the myocardial proteome was analyzed by two-dimensional electrophoresis (2-DE). Compared with the sham-operated group and the infarcted group, the result shows that 8 protein expressions in the verapamil treated group were up-regulated, and 7 protein expressions in this group were down-regulated significantly. Using MALDI-TOF-MS, 15 proteins with significant changes were identified through a database search. These proteins can be divided into 4 groups by their biological function: (1) Energy metabolism and mitochondrial function related proteins; (2) oxidative stress-induced proteins; (3) cytoskeletal Proteins; (4) other proteins. The findings show that the myocardial protective effects of verapamil in the myocardial damage process are related to the recovery of energy supply as well as anti-oxidative stress property.
Polybenzimidazole’s (PBI) was synthesized from 3,3'-diaminobenzidine and adipic acid by melting copolycondensation. Its thermal properties have been studied The molecular structure and thermal stability of the resulting polymers were characterized by means of FTIR, TGA and DSC. The results indicate that the melting temperature of the PBI is higher than 400°C and the polymer possesses excellent thermal stability. The onset decomposition temperature was determined to be 516°C, and the highest decomposition temperature reaches 536°C.
A kind of amino resinous intumescent flame retardants (IFR) was firstly synthesized, and the structure of the main composition was determined to be a caged bicyclic macromolecule containing phosphorus. The 30% weight of IFR was added into the flexible polyurethane foam (FPUF) to get retardant FPUF which has 26.5% of the limiting oxygen index. The date of CONE show that the heat release, smoke and gas of the flame retardant FPUF are much decreased and the activation energy decreases by 54 kJ?mol-1. It shows that the IFR can catalyze decomposition and carbonization of FPUF.
The goal of this work is to explore new polyimide materials that exhibit both high permeability and high selectivity for specific gases. Copolyimides offer the possibility of preparing membranes with gas permeabilities and selectivities not obtainable with homopolyimides. A series of novel fluorinated copolyimides were synthesized with various diamine compositions by chemical imidization in a two-pot procedure. Polyamic acids were prepared by stoichiometric addition of solid dianhydride in portions to the diamine(s). The gas permeation behavior of 2,2’-bis(3,4’-dicarboxyphenyl) hexafluoropropane dianhydride(6FDA)-2,6-diamine toluene (2,6-DAT)/ 1,3-phenylenediamine (mPDA) polyimides was investigated. The physical properties of the copolyimides were characterized by IR, DSC and TGA. The glass transition temperature increased with increase in 2,6-DAT content. All the copolyimides were soluble in most of the common solvents. The gas permeability coefficients decreased with increasing mPDA content. However, the permselectivity of gas pairs such as H2/N2, O2/N2, and CO2/CH4 was enhanced with the incorporation of mPDA moiety. The permeability coefficients of H2, O2, N2, CO2 and CH4 were found to decrease with the increasing order of kinetic diameters of the penetrant gases. 6FDA-2,6-DAT/mPDA (3∶1) copolyimide and 6FDA-2,6-DAT polyimide had high separation properties for H2/N2, O2/N2, CO2/CH4. Their H2, O2 and CO2 permeability coefficients were 64.99 Barrer, 5.22 Barrer, 23.87 Barrer and 81.96 Barrer, 8.83 Barrer, 39.59 Barrer, respectively, at 35°C and 0.2 MPa (1 Barrer=10-10 cm3 (STP)?cm?cm-2?s-1?cmHg-1) and their ideal permselectivities of H2/N2, O2/N2 and CO2/CH4 were 69.61, 6.09, 63.92 and 53.45, 5.76, 57.41, respectively. Moreover, all of the copolyimides studied in this work exhibited similar performance, lying on or above the existing upper bound trade-off lines between permselectivity and permeability. They may be utilized for commercial gas separation membrane materials.
A series of gelatin microspheres (GMs) were prepared through emulsification-coacervation method in water-in-oil (w/o) emulsions. The influence of preparation parameters on particle size, surface morphology, and dispersion of GMs was examined. The studied preparation parameters include concentration of gelatin solutions, concentration of the emulsifier, w/o ratio, emulsifying time, stirring speed, and so on. The surface morphology, dispersion, and particle sizes of GMs were determined by the scanning electron microscopy (SEM), SemAfore 4 Demo software, and particle size distribution graphic charts. The experimental results indicated that increasing the concentration of gelatin solution would increase the particle size of GMs. When the solution concentration increased from 0.050 to 0.200 g/mL gradually, the particle size increased correspondingly. The relationship between the two quantities was linear. On the contrary, increasing the concentration of the emulsifier would decrease the particle size of GMs. Furthermore, the particle size reduced quickly at initial time and slowed down latterly. With the increase of emulsifier concentration from 0 to 0.020 g/mL, the mean diameters of GMs decreased from 17.32 to 5.38 μm. However, the particle size dwindled slowly when emulsifier concentration was higher than 0.020 g/mL. The excellent result was obtained with the condition of 0.050 g/mL of emulsifier concentration, 0.100 g/mL of gelatin solution concentration, 1/5 of w/o ratio, 10 min of emulsifying time, and 900 r/min of the stirring speed. The GMs prepared at this condition had the smallest sizes, the narrowest size distribution, the best spherical shape, and fluidity. The w/o ratio has the same influence on particle size of GMs as that of gelatin solution concentration. With the increase of w/o ratio, the average particle sizes increased linearly, and the surface of microspheres become smoother as well. It is supposed that w/o ratio can be used to change the diameters and surface morphologies of GMs. The emulsifying time has little influence on the mean diameters of GMs, but it affects the dispersion of GMs apparently. When the emulsifying time was shorter than 5 min, the GMs had bad dispersion. After increasing the emulsifying time to 13 min, the dispersion of GMs changed greatly, whereas the dispersion of GMs became bad again when the emulsifying time was longer than 13 min. According to the experimental results, 13 min was considered to be the best emulsifying time. The stirring speed has the similar influence on GMs’ morphologies as that of emulsifying time. Slow stirring rate made large size distribution and bad spherical shape of GMs; excessive stirring speed results in aggregation among GMs likewise. The smaller size distribution and better spherical shape of GMs were observed under the stirring rate between 500 and 1500 r/min by SEM. In conclusion, increasing the concentration of gelatin solution or w/o ratio would increase the particle sizes of GMs, increasing the concentration of the emulsifier would decrease the sizes of GMs at proper emulsifying time, and stirring speed would get the best spherical shape of GMs. These are the basic laws governing the design and manufacture of the GMs.