使用6年后干熄炉氮化物结合碳化硅砖的变化

分析了在某170 t·h^(-1)干熄炉“牛腿”上部和下部使用6年后的氮化物结合碳化硅砖在化学组成、致密度、常温强度、高温强度、气孔孔径、物相组成、显微结构等方面的变化。结果表明:1)在170 t·h^(-1)干熄炉使用6年后,上部砖和下部砖的SiC含量和Si_(3)N_(4)含量均减少,SiO_(2)含量均大幅度增多(增多291.3%~722.5%),气孔孔径均增大(d 50增大22%~239%);上部砖的常温抗折强度和高温抗折强度大幅减小(分别减小47.9%和48.5%),下部砖的常温抗折强度和高温抗折强度小幅减小(分别减小8.6%和11.0%)。2)用后氮化物结合碳化硅砖的上述变化是氧化造成的。上部的氧化比下部的严重,表层的氧化比内部的严重。

干熄炉斜道区耐火材料的选用

比较了干熄炉斜道区常用的莫来石-碳化硅砖、莫来石-红柱石砖、氮化硅结合碳化硅砖等耐火材料的性能以及在实际应用中的情况。通过比较分析,新型红柱石耐火砖综合性能优良,性价比较高,可作为干熄炉斜道区主要采用的耐火材料制品,实现干熄炉长寿化的目标。

Study on the Changes of Non-structural Carbohydrates and Nitrogen Contents of Quercus aquifolioides Scrub along Different Elevation Gradient

[Objective] The aim was to compare the content changes between the non-structural carbohydrates（NSC）and the total nitrogen in various growing seasons,and to explore the response relationship between altitude and the contents.[Method] Taking Quercus aquifolioides scrub which widely distributed in Zheduoshan in the west of Sichuan as the experimental objects,the changes between NSC and the toal nitrogen in various growing seasons at different altitude were studied.[Result] The results showed that the content of NSC in Quercus aquifolioides underground increased with the lift of elevation in the dormancy,but decreased in the early germination,growing period and growth stage.The content of NSC in the ground tissue changed non-linearly with increasing elevation.In addition,the total nitrogen of Quercus aquifolioides organizations was decreasing with increasing elevation in the dormant period,which did not change significantly in the other periods.This result implied that the content of NSC in Quercus aquifolioides underground was more sensitive to temperature.[Conclusion] The experiment laid basis for the exploration of the physical and ecological mechanism of underground plants adaptability to highland environment,their response to global climate changes and adjustment to high altitude ecological system.

Study on the prediction of visible absorption maxima of azobenzene compounds

The geometries of azobenzene compounds are optimized with B3LYP/6-311G* method, and analyzed with nature bond orbital, then their visible absorption maxima are calculated with TD-DFT method and ZINDO/S method respectively. The results agree well with the observed values. It was found that for the calculation of visible absorption using ZINDO/S method could rapidly yield better results by adjusting OWFπ-π (the relationship between π-π overlap weighting factor) value than by the TD-DFT method. The method of regression showing the linear relationship between OWFπ-π and BLN-N (nitrogen-nitrogen bond lengths) as OWFπ-π=?8.1537+6.5638BLN-N, can be explained in terms of quantum theory, and also be used for prediction of visible absorption maxima of other azobenzne dyes in the same series. This study on molecules’ orbital geometry indicates that their visible ab- sorption maxima correspond to the electron transition from HOMO (the highest occupied molecular orbital) to LUMO (the lowest unoccupied molecular orbital).

Synthesis and Crystal Structure of Pd(AETYF)Cl_2CH_2Cl_2 [AETYF = 4'5'Diaza-9' (4,5-bis(ethylthio)-1,3-dithiole-2-ylidene)-fluorene]

A stable Pd(II) compound Pd(AETYF)Cl2CH2Cl2 (AETYF = 4?5?diaza-9? (4,5-bis(ethylthio)-1,3-dithiole-2-ylidene)-fluorene) has been synthesized and its crystal structure was determined by X-ray crystallography. The crystal is of monoclinic, space group P21/c with a = 15.249(6), b = 8.619(3), c = 19.078(7) ? b = 106.932(8), C19H18Cl4N2PdS4, Mr = 650.79, V = 2398.6(16) 3, Z = 4, Dc = 1.802 g/cm3, F(000) = 1296, m = 1.579 mm-1, Npar = 268, the final R = 0.0538 and wR = 0.1282 for 5068 observed reflections with I > 2s(I). The crystal structure determi- nation shows that the atoms of the molecule, except two ethyl-groups, are conjugated in a quasi- plane and these molecules are further stacked or contacted via plane to plane or edge to edge p-p interactions, forming parallel molecular chains along the b axis.

Nanostructuring gold wires as highly durable nano- catalysts for selective reduction of nitro compounds and azides with organosilanes

A general method is developed to prepare durable hybrid nanocatalysts by nanostructuring the surface of gold wires via simple alloying and dealloying. The resulting nanoporous gold/Au （NPG/Au） wire catalysts possess nanoporous skins with their thicknesses on robust metal wires specified in a highly controllable manner. As a demonstration, the as-obtained NPG/Au was shown to be a highly active, chemo-selective, and recyclable catalyst for the reduction of nitro com- pounds and azides using organosilanes as reducing agents.

Two-dimensional polymeric carbon nitride: structural engineering for optimizing photocatalysis

As a two-dimensional(2D) material, polymeric carbon nitride(g-C_3N_4) nanosheet holds great potentials in environmental purification and solar energy conversion. In this review, we summarized latest progress in the optimization of photocatalytic performance in 2D g-C_3N_4. Some of the latest structural engineering methods were summed up, where the relevant influences on the behaviors of photoinduced species were emphasized. Furthermore, the construction strategies for band structure modulation and charge separation promotion were then discussed in detail. A brief discussion on the opportunity and challenge of 2D g-C_3N_4-based photocatalysis are presented as the conclusion of this review.

Effects of leaf age,elevation and light conditions on photosynthesis and leaf traits in saplings of two evergreen conifers,Abies veitchii and A.mariesii

Aims Subalpine coniferous species are distributed over a wide range of elevations in which they must contend with stressful conditions,such as high elevations and extended periods of darkness.Two evergreen coniferous species,Abies veitchii and Abies mariesii,dominate at low and high elevations,respectively,in the subalpine zone,central Japan.The aim of this study is to examine the effects of leaf age,elevation and light conditions on photosynthetic rates through changes in morphological and physiological leaf traits in the two species.Methods We here examined effects of leaf age,elevation and light conditions on photosynthesis,and leaf traits in A.veitchii and A.mariesii.Saplings of the two conifers were sampled in the understory and canopy gaps at their lower(1600 m)and upper(2300 m)distribution limits.Important Findings The two species showed similar responses to leaf age and different responses to elevation and light conditions in photosynthesis and leaf traits.The maximum photosynthetic rate of A.veitchii is correlated negatively with leaf mass per area(LMA)and non-structural carbohydrate(NSC)concentration.LMA increased at high elevations in the two species,whereas NSC concentrations increased only in A.veitchii.Therefore,the maximum photosynthetic rate of A.veitchii decreased at high elevations.Furthermore,maximum photosynthetic rates correlate positively with nitrogen concentration in both species.In the understory,leaf nitrogen concentrations decreased and increased in A.veitchii and A.mariesii,respectively.LMA decreased and the chlorophyll-to-nitrogen ratio increased in understory conditions only for A.mariesii,suggesting it has a higher light-capture efficiency in dark conditions than does A.veitchii.This study concluded that A.mariesii has more shade-tolerant photosynthetic and leaf traits and its photosynthetic rate is less affected by elevation compared with A.veitchii,allowing A.mariesii to survive in the understory and to dominate at high elevations.