Auto-microfluidic thin-film chip for genetically modified maize detection

As a thin-film chip method, reverse dot blot hybridization (RDBH) has been employed to detect hazardous substances, but an automatic RDBH instrument with low workload, high accuracy and stability is still urgently needed. This paper presents our newly-developed auto-microfluidic thin-film chip (AMTC) method for multiplex screening of genetically modified (GM) maize. With specific DNA probes for genetically modified (GM) maize being immobilized on a square nylon thin-film, it was placed into a micro-reaction cell of the AMTC device. Then biotin-labeled PCR products with target DNA fragments for template amplification were added to the micro-reaction cell using a microfluidic system. When the PCR products passed the square nylon thin-film, the target DNA fragments were captured by the complementary action of DNA, where the signal was visualized with streptavidin link-coupled alkaline phosphatase color development kit. The sensitivity of GM maize detection reached 0.1% quality percentage and its stability and consistency could satisfy the requirements for practical applications. Performance advantages of the ATMC are manifold, being embodied in aspects such as easy and straightforward operation, low costs and less workload.     

城市高密度环境下的建筑学思考

以紧缩城市及城市高密度环境为预设,通过分析一些基于高密度条件的建筑实践,以建筑学的视角尝试从建筑空间、实体、功能,以及因建筑而留下的城市空间、建筑物之间的空间关系等方面探讨应对高密度的城市空间和发展模式的建筑方法和对策。     

Cuticular hydrocarbons of Tetramorium ants from central Europe: analysis of GC-MS data with self-organizing maps (SOM) and implications for systematics

Cuticular hydrocarbons were extracted from workers of 63 different nests of five species of Tetramorium ants (Hymenoptera: Formicidae) from Austria, Hungary, and Spain. The GC-MS data were classified (data mining) by self-organizing maps (SOM). SOM neurons derived from primary neuron separation were subjected to hierarchical SOM (HSOM) and were grouped to neuron areas on the basis of vicinity in the hexagonal output grid. While primary neuron separation and HSOM resulted in classifications on a level more sensitive than species differences, neuron areas resulted in chemical phenotypes apparently of the order of species. These chemical phenotypes have implications for systematics: while the chemical phenotypes for T. ferox and T. moravicum correspond to morphological determination, in T. caespitum and T. impurum a total of six chemical phenotypes is found. Three hypotheses are discussed to explain this disparity between morphological and chemical classifications, including in particular the possibility of hybridization and the existence of cryptic species. Overall, the GC-MS profiles classified by SOM prove to be a practical alternative to morphological determination (T. ferox, T. moravicum) and indicate the need to revisit systematics (T. caespitum, T. impurum).     

Application of Mismatch Detection Methods in DNA Computing

In many implementations of DNA computing, reliable detection of hybridization is of prime importance. We have applied several well-established DNA mutation scanning methods to this problem. Since they have been developed for speed and accuracy, these technologies are very promising for DNA computing. We have benchmarked a heteroduplex migration assay and enzymatic detection of mismatches on a 4 variable instance of 3SAT, using a previously described blocking algorithm. The first method is promising, but yielded ambiguous results. On the other hand, we were able to distinguish all perfect from imperfect duplexes by means of a CEL I mismatch endonuclease assay.     

Lattice Distortions and Charge Carriers in Cuprates

A phenomenological model with itinerant bands and local states trapped by thelattice on the Cu-sites, is discussed to describe global features ofcuprates. Relative energy positions of localized and itinerant states beingtuned (thermodynamically or by doping), the system must undergo first-orderMott metal-insulator transition. Decreasing the local level (from themetallic end of a stoichiometric compound), charge separation instabilityoccurs first before the Mott transition. Crossing and hybridization betweenlocal (flat) and itinerant bands introduce a structure in density of stateswhich may account for pseudogap features in cuprates. Modelresults in polaronic lattice effects and is rich enough to serve as aphenomenology of cuprates.     

A new approach to species determination for yeast strains: DNA microarray-based comparative genomic hybridization using a yeast DNA microarray with 6000 genes

DNA-DNA hybridization is known as the superior method in the elucidation of relationships between closely related taxa, such as species and strain. For species determination we propose a new DNA-DNA hybridization method: the DNA microarray-based comparative genomic hybridization (CGH) method, using a yeast DNA microarray with approximately 6000 genes. The genome from a yeast strain as a sample strain (Sample) was labelled with Cy3-dye and hybridized to a single DNA microarray, together with the Cy5-labelled genome of S. cerevisiae S288C as a reference strain (Reference). The log2 ratio values [log2[Cy3(Sample)/Cy5(Reference)]: Ratio] of signal intensities of all the gene spots were estimated and divided into the following groups: Ratio < or = -1; -1 < Ratio < 1; 1 < or = Ratio. The hybridization profiles of the genomes of type strains belonging to the genus Saccharomyces were significantly different from that of S. cerevisiae S288C. The Ratio-based grouping allowed us to discriminate between some species from S. cerevisiae more clearly. Furthermore, cluster analysis discriminated between closely related species and strains. Using this method, we were able to not only perform species determination but also to obtain information on alternation in gene copy number of such gene amplifications and deletions with single-gene resolution. These observations indicated that DNA microarray-based CGH is a powerful system for species determination and comparative genome analysis.     

Statistical thermodynamic analysis and designof DNA-based computers

A principal research area in biomolecular computing is the development of analytical methods for evaluating computational fidelity and efficiency. In this work, the equilibrium theory of the DNA helix-coil transition is reviewed and expanded, as applied to the analysis and design of oligonucleotide-based computers. After a review of the equilibrium apparatus for modeling the helix-coil transition for single dsDNA species, application to complex hybridizing systems is discussed, via decomposition into component equilibria, which are presumed to proceed independently. The alternative approach, which involves estimation of a mean error probability per hybridized structure, or computational incoherence, is then presented, along with a discussion of a special-case exact solution (directed dimer formation), and an approximate general solution, applicable to conditions of uniform fractional-saturation. In order to clarify the opposing nature of the predictions of these two models, simulations are presented for the uniform saturation solution for , as applied to a small Tag–Antitag (TAT) system, along with the behavior expected via isolated melting curves. By a comparison with the predictions of a recent, TAT-specific solution for , the views provided by these generalized approximate models are shown to define the opposing limits of a more general error-response.     

光敏性杂化SiO2波导薄膜的制备、表征及应用

利用有机/无机杂化方法制备了光敏性溶胶-凝胶（sol-gel）SiO2材料，在预生长了18μm厚的SiO2上包层的硅基片上旋涂成膜。经前烘、紫外曝光、后烘的薄膜在5μm×5μm的扫描范围内的表面粗糙度只有0．266nm，表面起伏度只有0．336nm。利用紫外光直写技术，制作出条形波导器件。SEM照片表明波导端面形状较好，侧壁陡直。对1×4多模干涉型分束器进行初步的通光测试，观察到分光效果较好的近场输出图像。     

纳米羟基磷灰石对肝癌细胞端粒酶基因表达的影响

研究羟基磷灰石（HAP）纳米粒子对Bel-7402人肝癌细胞端粒酶基因表达的影响。采用均相沉淀法制备出稳定单分散的HAP纳米粒子,应用透射电镜、电位粒度仪对其进行表征。HAP纳米粒子作用Bel-7402肝癌细胞4 h后,采用原位杂交技术检测Bel-7402肝癌细胞的端粒酶基因表达。结果表明HAP纳米粒子作用组的Bel-7402肝癌细胞的端粒酶阳性细胞比例为61.38%,而对照组的端粒酶阳性细胞比例为87.89%,2组有显著性差异（P〈0.01）。HAP纳米粒子可使Bel-7402肝癌细胞的端粒酶基因表达下调。