频散可控格式的一种推广形式及其在爆轰波马赫反射中应用

频散可控格式是高精度捕捉激波的新格式.对原有频散可控格式(DCD)进行了推广,给出了适用于网格点排列不规则情况下的DCD格式,使其具有更广泛的适应性,在此基础上构造了在非结构三角形网格下的DCD格式.用一些典型算例对推广后的DCD格式进行检验,结果表明该格式是合理和可靠的,并能够较好地保留原有DCD格式的二阶精度.把推广后的DCD格式和具有8种组分和20个化学反应的基元反应模型相结合,对氢氧爆轰波在直管道中的传播问题及楔面上马赫反射问题进行计算,计算结果和实验结果比较表明,在非结构三角形网格下的DCD格式能够有效地捕捉爆轰波,在爆轰波阵面上不会产生振荡或是抹平间断现象.

Characterization and Comparison of the Tissue-Related Modules in Human and Mouse

Background: Due to the advances of high throughput technology and data-collection approaches, we are now in an unprecedented position to understand the evolution of organisms. Great efforts have characterized many individual genes responsible for the interspecies divergence, yet little is known about the genome-wide divergence at a higher level. Modules, serving as the building blocks and operational units of biological systems, provide more information than individual genes. Hence, the comparative analysis between species at the module level would shed more light on the mechanisms underlying the evolution of organisms than the traditional comparative genomics approaches. Results: We systematically identified the tissue-related modules using the iterative signature algorithm (ISA), and we detected 52 and 65 modules in the human and mouse genomes, respectively. The gene expression patterns indicate that all of these predicted modules have a high possibility of serving as real biological modules. In addition, we defined a novel quantity, "total constraint intensity,'' a proxy of multiple constraints (of co-regulated genes and tissues where the co-regulation occurs) on the evolution of genes in module context. We demonstrate that the evolutionary rate of a gene is negatively correlated with its total constraint intensity. Furthermore, there are modules coding the same essential biological processes, while their gene contents have diverged extensively between human and mouse. Conclusions: Our results suggest that unlike the composition of module, which exhibits a great difference between human and mouse, the functional organization of the corresponding modules may evolve in a more conservative manner. Most importantly, our findings imply that similar biological processes can be carried out by different sets of genes from human and mouse, therefore, the functional data of individual genes from mouse may not apply to human in certain occasions.

低能He~(2+)-He反应中单电子俘获微分散射过程的实验研究

利用冷靶反冲离子动量谱仪装置系统研究了20—40keVHe2+-He碰撞体系的态选择单电子俘获过程,实验获得了单电子俘获过程的态选择截面以及角微分截面.在所研究的能区范围,电子俘获到L壳层的截面最大,为主要的反应道,这与分子库仑过垒模型的反应窗理论的预测一致.实验测量的态选择截面与原子轨道紧耦合的计算结果很好地符合,与光谱方法的测量结果存在一定的差别,主要原因是光谱方法不能测量完整的反应通道信息.实验结果表明,总角微分截面在小角度范围主要来源于电子俘获到基态的贡献,在大角度范围主要来自电子俘获到激发态的贡献;电子俘获到基态的和激发态的角微分截面均出现振荡结构,这种振荡来源于电子俘获反应中分子轨道之间的相干效应.实验测量的角微分截面与其他实验和紧耦合方法的计算结果进行了比较和分析.

岷江上游森林景观边界效应

应用地理信息系统和遥感技术对岷江上游森林景观在景观尺度上的边界效应进行了分析.结果表明:人工形成的林-农边界较清晰、其植被过渡明显,林地边缘的生物量低于林地内部,影响域为60m,农田边缘的生物量高于农田内部,边界效应范围为60～90m;自然形成的林-草边界过渡缓和,林地边缘的生物量低于林地内部,而草地边缘的生物量高于草地内部,边界效应对林地的影响范围为60m、对草地的影响范围为45～75m;林-灌边界的边界效应类似林-草边界,对林地影响域为60m,对灌木林地的影响域在45～75m之间.

Facile preparation of amperometric laccase biosensor with multifunction based on the matrix of carbon nanotubes-chitosan composite

The carbon nanotubes-chitosan (CNTs-CS) composite provides a suitable biosensing matrix due to its good conductivity, high stability, and good biocompatibility. Enzymes can be firmly incorporated into the matrix without the aid of other cross-linking reagents. The composite is easy to form insoluble film in solution above pH 6.3. Based on this, a facilely fabricated amperometric biosensor by entrapping laccase into the CNTs-CS composite film has been developed. At pH 6.0, the fungi laccase incorporated into the composite film remains better catalytic activity than that dissolved in solution. The system is in favor of the accessibility of substrate to the active site of laccase, thus the affinity to substrates is improved greatly, such as 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS), catechol, and 0, with K. values of 19.86 mu M, 9.43 mu M, and 3.22 mM, respectively. The major advantages of the as-prepared biosensor are: detecting different substrates (ABTS, catechol, and 02), possessing high affinity and sensitivity, durable long-term stability, and facile preparation procedure. On the other hand, the system can be applied in fabrication of biofuel cells as the cathodic catalysts based on its good electrocatalysis for oxygen reduction.

掺W对Bi系中高Tc超导相的影响

自Maeda发现高Tc超导体BiSrCaCuO以来,引起了人们广泛兴趣;由于它有较高的超导转变温度(Tc>100K),无剧毒、价廉和自高温冷却到室温无结构相变等特点,Bi系是一很有实用前景的高Tc超导体;已经确定Bi系中含有三个超导相(2201,2212,2223相),但是迄今要制得较纯的2223高Tc相还有一定困难,无疑这对它的基础研究和实用开发都受到了限制,因此制备更纯的Bi系2223相具有重要的意义。

Bi系中2212相的超导电性研究

已知在Bi系高Tc超导体中存在三个超导相:2223相的Tc～110k,c～37(?);2212相的Tc～85k,c～30.6(?);2201相的Tc～10k。在实验过程中,我们注意到还可能有另外的超导相存在,通过改变元素名义配比和制备工艺观察到一个具有2212相结构,但Tc却表现为～105k的新现象存在。 实验部分 样品制备采用固相反应方法将Bi_2O_3、PbO、Sb_2O_3、SrCO_3、CaCO_3、CuO(均为A.R.级)混匀、碾磨,于～810℃在刚玉坩埚中预烧20h;再碾,压片后于～870℃在磁舟中烧结60-240h,然后作测试分析。

自动绘图机中光学绘图头的控制

光学绘图不仅可以直接得到制版用的底片,而且绘图质量之高绝非接触式绘图可比拟。自动绘图机上增加一个光学绘图头,不仅可以绘各种线条,而且可以直接在底片上暴光得到各种符号。利用两个光点的符号,还可以一次绘出双线来。具有光学绘图头的自动绘图机,为需要制版印刷的部门提供了新的技术装备。本文阐述光学绘图头的结构和控制系统的工作原理。

湖泊现代化沉积物中磷的地球化学作用及环境效应

研究湖泊沉积物中磷的再迁移循环，对预防湖泊富养化现象发生和修复已污染湖泊具有重要意义。通过对沉积物柱芯孔隙水地球化学、沉积物中磷的不同化学相、沉积速率、磷沉积通量的研究，可以计算湖泊沉积物磷的释放通量。湖泊表层沉积物中积累的大量有机质的矿化分解和埋藏作用造成的沉积物中磷酸盐溶解解放，可能会使相当数量沉积磷重新回到水体，沉积磷可能成为造成湖泊富营养化问题的二次污染物源。