稀土含量对TRIP/TWIP钢晶粒及晶界特征的影响

利用XRD和EBSD分析稀土含量对TRIP/TWIP高锰钢相组成、晶粒及晶界特征的影响。结果表明,试验钢变形前组织以γ奥氏体为主,还有部分ε马氏体,经过塑性变形后,组织中还观察到少量α马氏体;随着稀土含量的增加,奥氏体转变为马氏体的量有所增加,表明稀土元素促进了试验钢的TRIP效应。此外,稀土元素的添加细化了试验钢中奥氏体晶粒,减少了小角度晶界数量而增加了大角度晶界数量,尤其是取向差为60°左右的大角度晶界;同时,稀土元素的添加也促进了低Σ值重位点阵(CSL)晶界特别是Σ3晶界的形成。     

MNi4.8Sn0.2（M=La, Nd）-supported multi-walled carbon nanotube composites as hydrogen storage materials

Two composites LaNi4.8Sn0.2/CNTs and NdNi4.8Sn0.2/CNTs were prepared by an impregnation-reduction method. Their hydrogen storage capacity could reach up to 2.96 wt% and 2.88 wt% respectively at room temperature and 1.0 MPa pressure. These values, which might result from the synergetic effect between the alloy nanoparticles and the pretreated CNTs, were three times higher than those of the unsupported MNi4.8Sn0.2 (M=La, Nd) alloys under the same conditions. XRD and TEM revealed that the alloy particles were uniformly dispersed on the CNTs and the average particle size was ca. 30 nm. The composites also showed good stability and the hydrogen storage capacity decreased by less than 6% after 100 adsorption-desorption cycles. Moreover, no noticeable change in crystalline structure was observed for the composites.     

1株具抑制一氧化氮合成酶活性放线菌菌株的分离和鉴定

 从云南河口采集的土壤中分离到1株稀有放线菌YIM30243^T.该菌株具有很强的抑制一氧化氮(NO)合成酶活性.通过对其进行的包括形态、生理生化特性、细胞壁化学组分以及16SrDNA序列等方面的多相分类研究,确定其为诺卡氏菌属的1个新种,我们将其命名为白色诺卡氏菌(Nocardiaalba sp.nov.).该菌株在大多数培养基上生长良好,气生菌丝呈黄白色至粉红白色,基内菌丝黄白至黄褐色.气生菌丝、基内菌丝均呈不规则断裂.     

An improved automatic detection method for earthquake-collapsed buildings from ADS40 image

Earthquake-collapsed building identification is important in earthquake damage assessment and is evidence for mapping seismic intensity. After the May 12th Wenchuan major earthquake occurred, experts from CEODE and IPSC collaborated to make a rapid earthquake damage assessment. A crucial task was to identify collapsed buildings from ADS40 images in the earthquake region. The difficulty was to differentiate collapsed buildings from concrete bridges, dry gravels, and landslide-induced rolling stones since they had a similar gray level range in the image. Based on the IPSC method, an improved automatic identification technique was developed and tested in the study area, a portion of Beichuan County. Final results showed that the technique＇s accuracy was over 95%. Procedures and results of this experiment are presented in this article. Theory of this technique indicates that it could be applied to collapsed building identification caused by other disasters.     

Slip rate along the Lijiang-Ninglang fault zone estimated from repeating microearthquakes

Seismicity and slip rates along the Lijiang-Ninglang fault zone between 1999 and 2006 were investigated with the waveform data recorded by the Yunnan digital Seismic Network. The relocated seismicity by the double difference method clearly exhibits different features between the northern and southern segments. More than 76% earthquakes occurred in the southern segment of the fault near the Lijiang area. The relocated seismicity appears to reflect the crustal velocity structure of the study area. Using cross-correlation analysis, we identified a total of 92 doublets and 70 multiplets that show high waveform similarity. Most of these sequences are aperiodic with recurrence intervals varying from a few minutes to hundreds of days. Using two sequences that occurred regularly over the study period, we obtained a fault slip rate of approximately 5 mm/a at ∼23 km, in good agreement with geologic and surface GPS measurement. Supported by National Basic Research Program of China (Grant No. 2004CB418405) and National Natural Science Foundation of China (Grant No. 40174014)     

Effect of Dy3+on osteogenic and adipogenic differentiation of mouse primary bone marrow stromal cells and adipocytic trans-differentiation of mouse primary osteoblasts

A series of experimental methods including 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test, alkaline phosphatase (ALP) activity measurement, mineralized function, Oil Red O stain and measurement were employed to assess the effect of Dy³⁺ on the osteogenic and adipogenic differentiation of mouse primary bone marrow stromal cells (BMSCs) and the adipogenic trans-differentiation of mouse primary osteoblasts (OBs). The results showed that Dy³⁺ had no effect on BMSC proliferation at concentrations of 1×10⁻⁸ and 1×10⁻⁵ mol/L, but inhibited BMSC proliferation at other concentrations. Dy³⁺ had no effect on OB proliferation at concentrations of 1×10⁻¹⁰ and 1×10⁻⁹ mol/L, but inhibited OB proliferation at other concentrations. Dy³⁺ had no effect on the osteogenic differentiation of BMSCs at concentrations of 1×10⁻⁹ and 1×10⁻⁷ mol/L, and promoted osteogenic differentiation of BMSCs at other concentrations at the 7th day. The osteogenic differentiation of BMSCs was inhibited by Dy³⁺ at concentration of 1×10⁻⁵ mol/L at the 14th day, but promoted osteogenic differentiation of BMSCs at concentrations of 1×10⁻⁹, 1×10⁻⁸, 1×10⁻⁷ and 1×10⁻⁶ mol/L with the maximal effect at concentration of 10⁻⁶ mol/L. Dy³⁺ promoted mineralized function of BMSCs at any concentration. Dy³⁺ had no effect on adipogenic differentiation of BMSCs at concentration of 1×10⁻⁷ mol/L, but inhibited adipogenic differentiation of BMSCs at other concentrations. Dy³⁺ inhibited adipocytic trans-differentiation of OBs at any concentration, suggesting that Dy³⁺ had protective effect on bone and the protective effect on bone may be mediated by modulating differentiation of BMSCs away from the adipocyte and inhibiting adipocytic trans-differentiation of OBs which may promote differentiation and mineralization of OBs. These results may be valuable for better understanding the mechanism of the effect of Dy³⁺ on pathogenesis of osteoporosis. Supported by the Foundation for Key Program of Ministry of Education of China (Grant No. 208018)     

Synthesis and characterization of N-aryloxo-functiona- lized β-ketoiminate rare-earth complexes and their catalytic activity for the polymerization of ε-caprolactone

The synthesis and characterization of dimeric rare-earth amides stabilized by a dianionic N-aryloxo functionalized ,8-ketoiminate ligand are described. Reactions of 4-（2-hydroxy-5-methyl-phenyl） imino-2-pentanone （LH2） with Ln[N（SiMe3）2]3（μ-Cl）Li（THF）3 in a 1：1 molar ratio in THF gave the dimeric rare-earth amido complexes [LLn{N（SiMe3）2}（THF）]2 [Ln = Nd （1）, Sm （2）, Yb （3）, Y （4）]. These complexes were well characterized, and the definitive molecular structures of complexes 3 and 4 were determined. It was found that complexes 1-4 can initiate the ring-opening polymerization of ε-caprolactone, and the ionic radii of the central metals have significant effect on the catalytic activity.     

考虑填充墙影响的底层薄弱结构抗震性能分析

填充墙既有减小结构周期而增大地震力的不利一面,也有增大结构层间侧移刚度的有利一面.汶川地震中,具有填充墙的底层薄弱结构破坏严重.根据等效刚度原则,把具有填充墙的框架转化为等效的纯框架,对七层底层薄弱结构进行小震下的弹性分析和大震下的弹塑性Pushover分析.结果表明,尽管填充墙使得结构中、上部层间角位移不同程度地减小,但却使得底层相对更加薄弱,层间变形比不考虑填充墙时大,填充墙对于底层薄弱结构有不利的影响.     

汶川地震都江堰市填充墙震害分析

统计分析了汶川地震中都江堰市钢筋混凝土框架结构填充墙的震害情况,通过对比主体结构与填充墙的震害并参照主体结构的抗震设防目标研究了填充墙自身的抗震性能.首先,统计分析了都江堰市钢筋混凝土框架结构主体结构的震害情况,结果表明主体结构满足我国三水准抗震设防目标;然后,将主体结构的地震反应划分为弹性反应和非线性反应两种,对比了这两种状况下填充墙与主体结构的震害,统计结果表明在这两种情况下填充墙的震害都明显高于主体结构,尤其是主体结构反应为弹性反应时,填充墙分别出现了15%和17%的严重开裂和倒塌;最后,探讨了填充墙构造措施对其抗震性能的影响,发现其现有构造措施不能满足地震作用下保持平面内完整性的作用,存在危及人员生命安全的隐患.本研究将为进一步研究填充墙地震破坏机理及其加固方法奠定基础.     

稀土微肥在林业生产上的应用

我国自20世纪80年代中期开展了稀土农用的研究,但林业上的实际推广应用还十分有限．多年的研究表明,稀土林用是一项低成本、高效益的林业增产技术。该文综述了稀土微肥的含义、近年来稀土肥在林业生产中的应用及效果,并对其增产机理、毒理作用、施用技术和注意事项作了分析介绍。结合福建省实际,对稀土微肥开发应用的前景进行了展望。