放电等离子烧结纳米复合Ti(C,N)基金属陶瓷

采用放电等离子技术（SPS）烧结制备出纳米复合Ti（C,N）基金属陶瓷材料。用光学显微镜、扫描电镜和能谱仪等对烧结体的孔隙率、微观组织和断口形貌等进行了观察,并对不同条件下材料的力学性能进行了对比分析。结果表明：直接升温到1250℃保温8min可获得较好的力学性能;在显微结构中,除了黑芯／白环的结构外,还存在着白芯／黑环结构;孔洞和大颗粒硬质相为主要的断裂源,断裂方式以沿晶断裂为主,同时存在着解理断裂和穿晶断裂。     

Effect of Dietary Restriction on DNA-Adduct Formation of Benzo[a]pyrene and 2-Acetylaminofluorene in Mouse Liver

Dietary restriction (DR) alters hepatic drug metabolizing enzyme activities that affect the metabolic activation of xenobiotics. Previously, we have studied the effect of DR on the formation of benzo[a]pyrene (BaP)-DNA adducts in male Fischer 344 rats. In this study, the effects of DR on the formation of specific BaP-DNA adducts in mouse livers were investigated. In addition, 2-acetylaminofluorene (2-AAF) modified DNA adducts in livers of mice and rats were also examined. DR reduced the body and liver weights of male B6C3F₁ mice. Both the total [³H]BaP-DNA binding and the specific BaP-DNA adduct, N²-dG-BaP, detected by ³²P-postlabeling technique, were found to be greater in DR mice than in animals fed al libitum (AL). The formation of the 2-AAF-DNA adduct, AF-C8-dG, was not affected by DR. Similar results were obtained from the in vitro DNA adduct formation of these two carcinogens mediated by rat and mouse liver microsomes. The effect of DR on the formation of BaP- and 2-AAF-modified DNA adducts is discussed.     

太阳能吸附式空气取水器和太阳能制冷结露法空气取水器的热性能分析比较

文中对吸附式空气取水器和制冷结露法空气取水器进行了热性能分析，得出取水率表达式，并以此为依据作了两者之间的取水率比较。     

某4缸柴油机台架振动特性的研究

对配置3种不同压缩刚度的隔振器的某4缸柴油机进行台架振动测试,处理了测试结果,分析了柴油机振动特性,结果表明,隔振器的刚度越大,柴油机的振动越小。     

Characteristics of coal quality and their relationship with coal-forming environment: A case study from the Zhuji exploration area,Huainan coalfield,Anhui, China

The comprehensive information of coal quality and its relationship with coal-forming environment in Zhuji exploration area, Huainan coalfield Anhui, China, have been studied. The data of coal quality including proximate and ultimate analysis, calorific values, sulfur forms, petrography and selected trace elements (Ga, Ge, V, U, Th, Cl and As) are based on 614 samples of 13 minable coal seams from 88 drilling holes collected during exploration periods. These data were designed to provide information on the technological performance of coal. Characteristics of coal quality deposited in three different sedimentary environments, namely in coal-bearing strata of the Shanxi Formation, Lower Shihezi Formation and Upper Shihezi Formation, were analyzed. Results show that moisture, volatile matter, and ash yield all increase stratigraphically upward, which is opposite to the variation of calorific values. The correlation between ash yield and calorific value shows negatively higher relevance that than of moisture and ash yield. The coal quality parameters of the boreholes along the divided faults were rarely controlled by geological setting. It was suggested that other factors such as magmatic activity and underground water cycling may modify the parameters of coal quality to some extent and cause their redistribution.     

Allelopathic research of subtropical vegetation in Taiwan II. Comparative exclusion of understory byPhyllostachys edulis andCryptomeria japonica

On many hillsides of Taiwan there is a unique pattern of weed exclusion byPhyllostachys edulis (bamboo) andCryptomeria japonica (conifer) in which the density, diversity, and dominance of understory species are very different. Although the physical conditions of light, soil moisture, and soil nutrients strongly favor the growth of understory in a bamboo community, the biomass of its undergrowth is significantly low, indicating that physical competition among the understory species in the bamboo and conifer communities does not cause the observed differences. However, the biochemical inhibition revealed by these two plants appeared to be an important factor. The growth ofPellionia scabra seedlings, transplanted from the study site into greenhouse pots, was evidently suppressed by the aqueous leachate of bamboo leaves but was stimulated by that of conifer leaves. The radicle growth of lettuce, rye grass, and rice plants was also clearly inhibited by the leachate and aqueous extracts of bamboo leaves but not by those of conifer leaves. Six phytotoxins,o-hydroxyphenylacetic,p-hydroxybenzoic,p-coumaric, vanillic, ferulic, and syringic acids were found in the aqueous leachate and extracts of leaves and alcoholic soil extracts ofP. edulis, while the first three compounds were absent in the extracts ofC. japonica. The phytotoxicities of extracts were correlated with the phytotoxins present in both leaves and soils. The understory species might be variously tolerant to the allelopathic compounds produced by the two plants, resulting in a differential selection of species underneath. Therefore, comparative allelopathic effects ofPhyllostachys edulis andCryptomeria japonica may play significant roles in regulating the populations of the understories.Paper No. 253 of the Scientific Journal Series of the Institute of Botany, Academia Sinica, Taipei, Taiwan. This study was supported by the National Science Council of the Republic of China.     

Paired electro-oxidation. I. Production of benzaldehyde

Oxidation of toluene to benzaldehyde by Mn³⁺ and OH free radicals, generated in the anodic and cathodic reactions respectively, was carried out simultaneously in the cathodic and anodic compartments of a cell. The selectivity of benzaldehyde was very high in both the anodic and cathodic reactions. The maximum total current efficiency for benzaldehyde production in the paired electrooxidation was 171%.     

Simulation of hourly wind speed and array wind power

Statistical summaries of wind speed are sufficient to compute many characteristics of turbine-generated power, such as the mean, variance and reliability of various power levels. However, a wind speed time series is necessary to produce a sequence of power values as used for investigating load matching and storage requirements. Since a long historical record of wind speed may not be available at a wind turbine candidate site, it is desirable to be able to generate a simulated numerical sequence of hourly wind speed values. Two such approximate procedures are developed in this paper. One procedure generates sequential wind speed values at a site based on the Weibull parameters of hourly wind speed and the lag-one autocorrelation of hourly wind speed values. Comparison with historical data at a site is made. The second procedure generates sequential hourly wind power values for a regional array of wind turbines. It utilizes the typical site wind characteristics, the spatial and lag-one cross correlation and autocorrelation of hourly wind speed values and an equivalent linearized relationship between array average wind speed and array power. Comparison with results for six different wind turbines in three different regional arrays indicates good agreement for wind power histograms, autocorrelation function and mean persistence.     

Ignition of carbon nanotubes using a photoflash

When fluffy carbon nanotubes (CNTs) are subjected to a photoflash, there is a rapid increase in temperature to over 475 °C within 0.03 s. This is attributed to absorption of the light by the CNTs, which results in the generation of an acoustic wave and oxidation of the CNTs. Ignition is due to the exposure of the flammable catalytic particles embedded in CNTs to air. The appearance of sub-micrometer iron oxide particles in the samples indicates that the oxidized iron nanoparticles formed due to flash exposure may agglomerate or fuse depending on the amount of iron catalysts and CNT fluff temperature which is increased due to flash absorption.     

Conjugation and Evaluation of Triazole‐Linked Single Guide RNA for CRISPR‐Cas9 Gene Editing

The CRISPR‐Cas9 gene editing system requires Cas9 endonuclease and guide RNAs (either the natural dual RNA consisting of crRNA and tracrRNA or a chimeric single guide RNA) that direct site‐specific double‐stranded DNA cleavage. This communication describes a click ligation approach that uses alkyne–azide cycloaddition to generate a triazole‐linked single guide RNA (sgRNA). The conjugated sgRNA shows efficient and comparable genome editing activity to natural dual RNA and unmodified sgRNA constructs.