化学气相反应法制备Zr-Si-C涂层

为了提高Zr-Si-C涂层与基体的结合强度,基于粉末埋入反应辅助涂覆工艺,采用新型化学气相反应法在SiC陶瓷表面制备Zr-Si-C涂层.SiC陶瓷基片被包埋于Zr-1%(质量分数)I2混合粉体中,在850～1 100 ℃进行化学气相反应.碘促进Zr原子向SiC陶瓷表面的传输,Zr与SiC之间的扩散反应导致在SiC表面生成连续的Zr-Si-C复合涂层.采用X射线衍射、扫描电镜结合X射线能谱分析以及相图分析确定了涂层微结构及相组成.结果表明:复合涂层内层为ZrC、中间层为Zr2Si-ZrC1-x复相区、外层为ZrC1-x.通过测量涂层厚度研究了涂层的生长动力学,在850～1 100 ℃范围内,涂层生长符合抛物线规律,活化能为(210±20)kJ/mol.     

Microstrip linear slot array antenna for X-band

The X-band microstrip slot antenna array is described as an attempt to achieve moderate bandwidth and overcome the problems of radiation from microstrip feed lines and surface waves in the dielectric. The discussion covers development of a mathematical simulation that computes the radiation pattern of a single microstrip slot and the feeding microstripline; construction of a uniform broadband microstrip slot antenna array; development of a mathematical simulation that computes the radiation pattern in the H- and E-planes; and investigation of the mutual coupling between the slots. A comparison is made between computed and measured results at X-band frequencies     

Sense and nonsense in hierarchical regression analysis: Comment on Smyth.

Contrasts ANCOVA via hierarchical regression analysis with hierarchical analyses used by L. D. Smyth (see record 1983-07281-001) in his article on psychopathology as a function of neuroticism. It is shown that Smyth's analyses did not address the hypotheses he wished to test and that the results yielded by these analyses are meaningless. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optical properties of metallic films for vertical-cavity optoelectronic devices

We present models for the optical functions of 11 metals used as mirrors and contacts in optoelectronic and optical devices: noble metals (Ag, Au, Cu), aluminum, beryllium, and transition metals (Cr, Ni, Pd, Pt, Ti, W). We used two simple phenomenological models, the Lorentz-Drude (LD) and the Brendel-Bormann (BB), to interpret both the free-electron and the interband parts of the dielectric response of metals in a wide spectral range from 0.1 to 6 eV. Our results show that the BB model was needed to describe appropriately the interband absorption in noble metals, while for Al, Be, and the transition metals both models exhibit good agreement with the experimental data. A comparison with measurements on surface normal structures confirmed that the reflectance and the phase change on reflection from semiconductor-metal interfaces (including the case of metallic multilayers) can be accurately described by use of the proposed models for the optical functions of metallic films and the matrix method for multilayer calculations.     

Pressure-Assisted Combustion Synthesis of Dense Layered Ti3AlC2 and its Mechanical Properties

A near-single-phase Ti₃AlC₂ ternary carbide was synthesized from 3Ti–1.1Al–1.8C powder blend, both by the wave propagation and thermal explosion (TE) modes of self-propagating high-temperature synthesis. The application of a moderate (28 MPa) pressure immediately after TE at 800°C (reactive forging) yielded a 95% dense material containing, in addition to Ti₃AlC₂, an appreciable amount of TiC_{1− x} . By adjusting the starting composition, a 99% dense material containing up to 90 vol.% Ti₃AlC₂ was obtained. The material had a fine-layered microstructure with Ti₃AlC₂ grain size not exceeding 10 μm. The samples were readily machinable and had a high compressive strength of ∼800 MPa up to 700°C.     

Sensory and quality analysis of different melon cultivars after prolonged storage

The purpose of this work was to evaluate the sensory and general quality of four different melon cultivars (Cucumis melo L.) immediately after harvest and at the end of storage and marketing simulation. After 16 days of storage at 5 degrees C and additional 3 days at 20 degrees C, only cultivar 'C-8' had a poor general appearance due to significant low firmness and relatively high decay incidence compared to the cultivars '5080', 'Ideal' and '7302'. The cultivar '7302' was found to have the higher overall quality. The human-sensory and organoleptic analyses revealed that the cultivars can be differentiated on the basis of retronasal odour. The texture of the melons seems to be dependent on the genotype. All the complex perceptions analysed in this work contribute to the acceptability, which is in the fresh fruits of '7302' the best and in 'Ideal' the worst. After storage and marketing simulation 'Ideal' and 'C-8' are no longer favoured, but '5080' and '7302', despite different characters, were found to be similarly accepted. It can be concluded that with the aid of the human-sensory method developed to characterize the melon varieties it is possible to distinguish the different genotypes.     

Microwave Discharge of O2 and CO2 as a Synthetic Tool for Oxidations of Unsaturated Compounds Adsorbed on Solid Supports

Cis and trans stilbene, styrene, 1-decene and 6-dodecene adsorbed on silica gel were reacted with oxygen atoms produced by microwave discharge of O₂ and CO₂. At 0°C these compounds gave mainly epoxides and carbonyl compounds as in neat liquid reactions. Below — 60°C ozonolysis products were formed; cis and trans stilbene and styrene gave benzaldehyde while 1-decene and 6-dodecene resulted mainly in ozonides.     

Anti-proliferative activities,phytochemical levels and fruit quality of pepper (Capsicum spp.) following prolonged storage

Peppers are rich in health-promoting phytochemicals, which are involved in the defence mechanisms against cancer. To select a lead variety of pepper with anti-proliferative activity against colon cancer cells and liver cancer cells, high antioxidant activity, and high concentrations of capsaicin, flavonoids and phenolics, we compared these attributes in nine different pepper accessions belonging to Capsicum annuum and C. chinense. Quality parameters such as weight loss and total soluble solids content were tested as well. The different parameters were determined immediately after harvest and after prolonged storage and marketing simulation. A significant variation of these traits was detected among the accessions. C. chinense line 1745 had the highest antioxidant activity, the highest levels of capsaicin and flavonoids, a high and specific anti-cancer activity, and the lowest weight loss level during postharvest storage. It is proposed that line 1745 has potential for use as a source for health-promoting traits and should be further evaluated for use as a nutraceutical for the prevention and treatment of colon and liver cancers.