二氧化硅改性片状铁粒子的微波吸收性能

The preparation and microwave-absorbing behavior of micrometric silica-modified platelet iron particles (SMPLIP) were investigated. Through precipitation， hydrothermal reaction， silica-modification and reduction with hydrogen， micrometric porous SMPLIP were yielded. The permittivity values of SMPLIP had been significantly decreased due to the presence of silica. Measurements and calculations showed that a 1.93mm thick sample containing SMPLIP as much as 60% by weight was capable of absorbing X band(8.2～12.4GHz) microwaves with reflection loss being greater than -10dB within the frequency range of 8.2～11.36GHz， while the maximum re-flection loss was -14.8dB at 9.4GHz. The results had also shown that it was practicable to prepare thin， light-weight microwave absorbent with SMPLIP.     

纳米镍-铁合金/膨胀石墨复合材料的制备、表征及其电磁屏蔽性能

The composites with nano-particles of Ni-Fe alloys dispersed on the nano-layers of expanded graphite (EG) were prepared by the impregnation of EG with ethanol solutions of nickel and iron acetates， followed by drying and reduction in H₂. The square nano-particles of Ni-Fe alloys with particle sizes of mainly 20～40 nm were found to be well spread on the layers of EG. The alloy nano-particles exhibited high shielding effectiveness (SE) for electromagnetic radiations at low frequencies due to their high magnetic conductivity. Since EG is electronically conductive and displayed high SE at high frequencies， the composites exhibited good SE at wide range of frequencies. The electric and magnetic conductivities of the composites could be monitored through regulating the loadings of alloy nano-particles on EG， and it was found that the composites with 20%～40% of the alloys exhibited good SE. Specifically， the composite 27%Ni-3%Fe-EG showed the excellent SE from 66 to 110 dB at the frequencies from 300 kHz to 1.5 GHz.     

Optical band gap and conductivity measurements of polypyrrole-chitosan composite thin films

Electrical conductivity and optical properties of polypyrrole-chitosan（PPy-CHI） conducting polymer composites have been investigated to determine the optical transition characteristics and energy band gap of composite films.The two electrode method and I-V characteristic technique were used to measure the conductivity of the PPy-CHI thin films,and the optical band gap was obtained from their ultraviolet absorption edges.Depending upon experimental parameter,the optical band gap（E_g） was found within 1.30-2.32 eV as estimated from optical absorption data.The band gap of the composite films decreased as the CHI content increased.The room temperature electrical conductivity of PPy-CHI thin films was found in the range of 5.84×10^-7-15.25×10^-7 S·cm^-1 depending on the chitosan content.The thermogravimetry analysis（TGA） showed that the CHI can improve the thermal stability of PPy-CHI composite films.     

多晶铁纤维的合成与微波吸收性能的研究

The preparation and microwave-absorbing behavior of polycrystalline iron fibers modified with the thermal decomposition of carbonyl iron were studied in this paper. Through preparation of α-FeOOH fiber precursor, dehydration, reduction with hydrogen, modification with the thermal decomposition of carbonyl iron and passivation, polycrystalline iron fibers were yielded. α-FeOOH fiber precusor with optimum diameter and aspect ratio was made by using uniform seed crystal with optimum concentration and controlling the reaction time. Lacunas from procedure of dehydration and reduction were well modified with carbonyl iron. The sample with 1.95 mm thickness containting 60 % by weight of modified polycrystalline iron fibers showed reflection loss over 10 dB within the frequency range of 8.5～14.6 GHz, and the maximum reflection loss was 21.8 dB at 11.3GHz, while the sample of nonmodified polycrystalline iron fiber showed less reflection loss under same conditions.     

Synthesis and Luminescent Properties of Novel Nanometer-sized ScAlMgO_4：Eu~（3＋） Phosphors for PDP

Novel nanometer-sized ScAlMgO4:Eu3+ phosphors were successfully synthesized by the citric acid complexation method.The mean particle size of the obtained powders was within the range of 100～150 nm according to the SEM patterns.In ScAlMgO4:Eu3+ showed strong characteristic red emission,of which the maximum emission peak was located at 629 nm for ultraviolet(UV) excitation.The dependence of photoluminescence intensity on Eu3+ concentration was also studied in detail,and the emission intensity of Sc1-xEuxAlMgO4 was about 10% at optimized Eu3+ concentration.Furthermore,the luminescence decay measurements showed that the lifetimes of Eu3+ were in the range of millisecond.The obtained ScAlMgO4:Eu3+ phosphors with nanometer size and excellent luminescence efficiency would be potential red phosphors in plasma display panels.     

Nickel ferrite spinel as catalyst precursor in the dry reforming of methane:Synthesis,characterization and catalytic properties

Dry reforming of methane by CO2 using nickel ferrite as precursor of catalysts was investigated.Nickel ferrite crystalline particles were prepared by coprecipitation of nitrates with NaOH or ammonia followed by calcination,or by hydrothermal synthesis without calcination step.The textural and structural properties were determined by a number of analysis methods,including X-ray diffraction (XRD),Raman spectroscopy and X-ray photoelectron spectroscopy (XPS),among which X-ray diffraction (XRD) was at room and variable temperatures.All synthesized oxides showed the presence of micro or nanoparticles of NiFe2O4 inverse spinel,but Fe2O3 (hematite) was also present when ammonia was used for coprecipitation.The reducibility by hydrogen was studied by temperature-programmed reduction (TPR) and in situ XRD,which showed the influence of the preparation method.The surface area (BET),particle size (Rietveld refinement),as well as surface Ni/Fe atomic ratio (XPS) and the behavior upon reduction varied according to the synthesis method.The catalytic reactivity was investigated using isopropanol decomposition to determine the acid/base properties.The catalytic performance of methane reforming with CO2 was measured with and without the pre-treatment of catalysts under H2 in 650-800 C range.The catalytic conversions of methane and CO2 were quite low but they increased when the catalysts were pre-reduced.A significant contribution of reverse water gas shift reaction accounted for the low values of H2 /CO ratio.No coking was observed as shown by the reoxidation step performed after the catalytic reactions.The possible formation of nickel-iron alloy observed during the study of reducibility by hydrogen was invoked to account for the catalytic behavior.     

SnO2纳米粒子的制备与表征

The SnO2 nano-particles with rutile structure were prepared by a Water/Oil (W/O) microemulsion system, composed of Triton X-100 1-hexanol/Cyclohexane/Water. The particles were also compared with that synthesized by citric acid method. The powders were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and infrared spectroscopy (IR). The result showed that the SnO2 particles prepared by microemulsion had fine shape and narrow range of particle size distribution. The crystallite size calcined at 600℃ was 11.49 nm,while the crystallite size prepared by citric acid method was about 17.4 nm.     

Synthesis dibromo substituted BOPHY dye for the singlet oxygen generation

A dibromo substituted BOPHY derivative(2) was prepared and found to exhibit photo-sensitization capability. Rapid oxidation of 80% DPBF at the first 6 min was observed suggesting that 2 is a superior photo-sensitizer than methylene blue. The HOMO–LUMO band gap for the lowest energy absorption bands of the BOPHY 1 is smaller than that of PS 2, which is in good agreement with the red shift in the absorption observed between 1 and 2.     

Infrared Studies on Shock-loading Jilin Meteorite

The shock wave techniques which were first come into use investigated the mid-infrared spectra of shock-loading Jilia meteorite for shock recovery specimen. Through the structural variation of the shocked mineral in Jilin meteorite the chondritic shock metamorphism is studied. The results of the infrared spectra of shock recovery specimen show that the characteristic IR bands of polymorphs, phase transformation and high-pressure phase for both olivine and pyroxene almost were not found at the pressure over 12 GPa. The diaplectic glass occurs at the pressure between 53.0 and 77.5 GPa. The absorption band at 1740 cm~(-1) is assigned to the C = O stretching vibration as a sign of diaplectic glass occurring. The IR of recovery specimen has revealed that the vitreous materials in unshocked Jilin meteorites were primary remainders of meteoritic parent.     

A novel impedance immunosensor based on O-phenylenediamine modified gold electrode to analyze abscisic acid

<正>An impedance immunosensor based on O-phenylenediamine modified gold electrode for the determination of phytohormone abscisic acid(ABA) was proposed.The operating pH,absorption time,absorption temperature and concentration of anti-ABA antibody were investigated to optimize the analytical performance.The calibration curve for the determination of ABA was obtained from this impedance immunosensor under optimal conditions.The results showed that the detection limit at about 1 ng/mL in the range of 10-5000 ng/mL.