In this paper,the essential oils from Agarwood A and B collected in Hainan,China,were extracted by low temperature-dynamic microwave method.And the SPME-GC-MS technique was performed to analyze the volatile constituents in essential oil.58 and 68 volatile components were identified from A and B,respectively,in which 41 compositions are the same,and the main volatile constituents in two essential oil were sesquiterpene in which the composition of the highest relative content was the decalin type ones accounting for 42.35% and 41.85%,respectively.Based on the biosynthetic nature that biosynthesis in the same plants tends to have the same origin and the way of synthesis,its secondary metabolites have often similar structure,the highest peak in two chromatograms were identified as acetate-1,2,3,4,4a,7,8,8a-octahydro-2,4a,5,8a-tetramethyl-1-naphthalenyl ester.In addition,6 main compounds in A and B were the same,which proved that they possessed the similar scent.However,their aroma quality was different because there were 5 unique decalin type compounds in A,which illustrated the top note of A was different from B.On the other hand,there were 14 distinctive compounds of longer retention time in B,which said that the oil B had longer holding time of fragrance than A.Furthermore,the SPME-GC-MS technique was an effective way to evaluate the quality of Agarwood essential oils according to the results comparing to the fragrance constituents in Agarwood essential oils extracted by 4 different extraction methods.

Fragrance constituents in essential oils from the off-cuts of Eaglewood (A) and Chinese Eaglewood (B) in Guangdong have been analysed by GC-MS. Essential oil A was extracted by microwave additional extraction method, and oil B was provided by a flavors company. SPME-GC-MS analyses revealed that two oils possessed 29 same compounds, and their main fragrance compositions were sesquiterpene accounting for 94.99% and 94.19% of total essential oils, respectively. However, oil A exhibited 61 volatile compounds with agarospiro (17.32%), guaiac acetate (15.99%), guaiol (15.53%) and beta-Ionon (13.61%) being the major constituents. Oil B had 59 ones, and the major constituent was spathulenol (56.45%). In the first 60 min, oil B showed 28 distinctive compounds. And in 78~91 min, oil A displayed 14 fragrance compositions, while, oil B showed 1. The results explained that two essential oils possessed similar scent. However, their aroma quality was very different. Oil A showed longer holding fragrance. However oil B exhibited richer top note. This study demonstrated that offcuts of Eaglewood would also be used to extract essential oil to provide new variety of material for perfume industry.

Industrial microwave extraction technology is still in the exploratory stage, and design and improve- ment of large-scale equipment must depend on microwave extraction technology; pilot-scale experiments showed that： selecting the appropriate microwave effective exposure time, the microwave power and the solid-liquid ratio is conducive to energy conservation and efficiency; The extraction index （A） and energy consumption index （B） were obtained from the corresponding experimental data, and the experimental results show： when the ex- traction rates were greater than or equal to 95% , the energy consumption of dynamic microwave extraction is less than one of the solvent extraction 20% - 67%. Thus, relative to the solvent reflux extraction, microwave extraction is a new energy efficient technology; A new evaluation for large-scale microwave extraction equipment was shown by two indexes A and B at the same time.

The kelp extract is nutrient-rich and natural flavor, which was made by microwave extraction in low-temperature. In this paper the drying method for the kelp extract was studied, including the single factor method and L9（3^4） orthogonal experimental design method, then the factors to effect removing the dried block from a plate was discussed. The main 4 factors to effect drying result are temperature, vacuum, the sample thickness and water content of the extract. Our experiments shows that the best drying conditions are drying temperature 90 %, vacuum 0.1 MPa, sample thickness of 1 cm, 16% moisture content before drying, and drying time of 50 min. Under the above condition, the drying process is simple and fast, average drying rate is 0.6056 g/min, moisture content of dried kelp extract is 5.82%, and the dried block is easily removed from the plate.

Measured and analyzed were the capacitance frequency spectrum and the complex impedance of SrTiO3 varistor based on oxidation heat treatment. Obtained results show that the increase of heat treatment temperature for promoting varistor voltage will bring the capacitance dispersion frequency down notably, and the grain resistance increases obviously. The main features of capacitance frequency curve recognize that the capacitance dispersion region results from the mechanism of interface relaxation polarization. The formulas from an interface relaxation equation for the calculation of specific relaxation time and capacitance dispersion frequency are related to the electrophysics parameters of the grain and grain boundary. The calculations of dispersion frequency are coinciding with the measure values qualitatively. Analysis indicates that grain resistance increase obviously with the increase of heat treatment temperature due to oxygen diffusing into the grain excessively. It is a predominant reason on the decrease of dispersion frequency.

Using BaCO_ 3 and SnO_ 2 as starting materials, a little of SiO_ 2 ,Bi_ 2 O_ 3 and Sb_ 2 O_ 3 as additives and Ta_ 2 O_ 5 as donor, semiconducting BaSnO_ 3 ceramics with 97%-99% of theoretic density and 8μm of average grain size were prepared by solid-state reaction method. The effect of grain boundaries was enhance effectivelyby using Na_ 2 CO_ 3 andMn(NO_ 3 )_ 2 as acceptors. The results indicatedthat the resistivity of BaSnO_ 3 ceramics was increased obviously,and the grain boundary resistance was larger than the grain resistance by Na_ 2 CO_ 3 doping with Mn(NO_ 3 )_ 2 .When Mn(NO_ 3 )_ 2 content was 1mol, the BaSnO_ 3 ceramics have the resistivity 3.3×10 6 Ω·cm and the grain resistivity 4.3Ω·cm, and the grain boundary barriers estimated by determinating the conduction activation energies was about 0.5eV.

Effect of Ag diffusion of Pd-Ag inner electrode on electric properties of multilayer chip ZnO varistor was studied. The results show that Ag contents in inner electrode play a very important role in the electric properties of multilayer chip ZnO varsitor. When the Ag content is less than 90%, the properties are good, but when the Ag content is more than 90%, the properties deteriorate with the increase of the Ag content. And the properties of MLCV having pure Ag inner electrode are the worst. The capacitance reflecting the grain-boundary barrier capacitances decreases with the increase of Ag content. The analyses of V - I characteristic curves and complex impedances indicate that, during the co-firing process of the ceramic and inner electrode, with the increase of Ag content in inner electrode, the velocity of Ag diffusing in the ZnO lattice will speed, and the grain resistance increases excessively, and the electric properties of MLCV deteriorate.

Properties of the oxidized surface layer of SrTiO3 ceramic ring capaciter-varistors which were reoxidized at different temperature of 800~1 050℃ in aerial were studied with polishing layer by layer and electrical measurement. It is found that the components have obvious surface layer structure; the depth of oxidized surface layer increases with the increase of treatment temperature ( the depth of oxidized surface layer of the samples which were reoxidized at 800~1 000℃ ranges, is from 26 μm to 107 μm); the density of diffused oxygen and the high of the potential barrier of grain in the oxidized surface layer decrease from the surface to the inside.

Measured and analyzed were the volt-ampere characteristics of SrTiO3 varistor based on oxygen-diffusion heat treatment. Obtained results show that both height of interface barrier and varistor voltage will increase continuously, but nonlinear coefficient increase firstly and then decrease with the increase of heat treatment temperature. The thickness of diffusion-layer will increase continuously while the increase of heat treatment temperature. The presence and change of the diffussion-layer are supported by the experimental fact of a complex impedance plots,i.e. the resistance of grain increase with the increase of heat treatment temperature.

The electrical properties of TiO2-based varistor ceramics doped with Ta_2O_5 and Nb_2O_5 were studied. Test samples were prepared with the formula of TiO_2+0.003 (in mole, the same below) (SrO+Bi_2O_3+SiO_2)+xTa_2O_5+yNb_2O_5, where x=0.00075, y=0; x=0.000375, y=0.000375 and x=0, y=0.00075 respectively. Based on the results of measurements of electric current—voltage and capacitance, impedance analysis and barrier height measurement, the working mechanism of Ta_2O_3 and Nb_2O_5 was analyzed. It is found that the sample of x=0.00075 exhibits a lowest breakdown voltage gradient (E_(10mA)) of 7.9 V/mm and a biggest apparent dielectric constant of 5.88×10~4, while the sample of y=0.00075 exhibits a highest breakdown voltage gradient (E_(10mA)) Of 48.9 V/mm and a smallest apparent dielectric constant of 1.39×10~4. It shows that the doping of Ta_2O_5 can reduce the breakdown voltage gradient and raise the apparent dielectric constant effectively.

基于ZnO压敏电阻器的电子态特征,界面肖特基势垒不仅对其导电性能,而且对其介电性能也有决定性的影响.分析了三种可能导致电容弥散现象的机制,它们都与界面势垒的性状密切相关,给出的一些估算结果,与实验所得规律和数据基本符合.依据有效媒质理论的分析,认为不一致的晶界势垒高度是导致低频端的电容量随频率降低反常地升高的原因之一.

Based on the model of conduction mechanism, we considered that the nonlinear property is correlated with the height and width of interface barrier of ZnO varistor ceramics, and, interface state density Ns, donor concentration Nd, and their distributions are main parameters influencing the barrier. Analysis indicated emphatically that the preconditions of established barrier expression should be complied while the influence of the parameters on the barrier analyzed by using the expression. An important revelation is that the Ns value and distribution must be increased and improved accordingly for keeping well nonlinear property while the Nd is increased. In practice, the property,cost, and processing facility should be all things considered to choose optimized matching values of these parameters. 

为用溶胶-凝胶技术制备BaTiO3薄膜,以乙酸钡、钛酸丁酯、乙酸、乙醇等为原料配制的前驱溶液系统,加入适量的乙酰丙酮作螯合剂,可得到性能稳定的溶胶;利用FTIR分析,揭示了该溶液系统中的相关的化学反应机制.分析结果表明:该溶液系统的胶化主要取决于钛酸丁酯的逐步水解并与包括乙酸钡在内的其他有机分子的聚合;乙酸不仅作为乙酸钡的溶剂,而且能有效地减缓钛酸丁酯的水解速率而维持溶胶的稳定性;乙酰丙酮螯合剂的引入能控制金属有机分子的聚合度.

分析指出耗尽层内施主浓度Nd、界面受主态密度Ns 和界面能级深度Es 是影响ZnO压敏陶瓷电性能的重要参数.Nd 与体内原子缺陷有关,室温下主要取决于电离的浅能级本征和非本征施主Zn@i, Zn¨i 和Al@Zn,Ns 和Es 与界面原子缺陷密度和性质有关.本征界面缺陷 V′Zn 和 V″Zn 对界面受主态形成起基本作用;偏析于晶界的大离子半径的Bi和Ba以及界面上的化学吸附氧O-和O2-对提高Ns 和Es 起关键作用;易变价过渡元素Mn,Co和Ni对进一步提高受主态密度起重要作用;Sb通过生偏锑酸钡相在稳定势垒方面起较大作用,对提高态密度也有一定帮助.

An analysis based on property of the acceptors at grain boundaries of semiconducting n- TiO2 varistor ceramic and the distribution with multi energy levels were considered in this paper. The I-V nonlinear characteristic of the ceramics was explained reasonably by thermo - electron emission model of grain boundary barrier. The relation of nonlinear coefficient a in proportion to the voltage at grain boundary was induced theoretically, and related to distributing function of acceptor state density in the grain boundary.

By microstructure analysis, I - V characteristics and complex impedance spectra measurement, the microstructure and related electric properties for the varistors based on SrO-Nb2O5-TiO2 semiconducting ceramics with different doped amounts of Nb5+ and Sr2+ were investigated. The distribution and effects of Nb5+ and Sr2+ on electric properties for the materials were discussed. The results show that Nb5+ dissolves into TiO2 grains substitutes Ti4+ to enhance ceramic semiconducting behavior, and proper addition of Nb-doped amount can avail grain growing. The Sr2+ mainly distributes in grain boundary areas, which behaves as an interface acceptor state and so influences on the electric properties of varistor markedly. The experimental results on post heat-treatment in air show that the varistor voltage is increased observably with heat-treatment temperature above 800degreesC, but the nonlinear coefficient is ameliorated only at an appropriate temperature range.

Thick film humidity sensors were prepared by the screen－printing technique starting from Zn2SnO4－LiZnVO4 system nanometer powders obtained by Sol－gel method.Compared with other sensors made by ordinary ceramic powders, the humidity sensor has the advantages of lower resistance atlower humidity and long－term stability. Properties measured at different operating frequencies indicate that the sensor has the characteristic of linear sensitivity at 1kHz. The results of complex impedance analysis indicate that better microstructure resulted from nanometer powders and sintering at proper tem－perature is the reason of better properties for the humidity sensors.