Application of Power Spectral Density Analysis in STM

The tunneling-current signals which acquired by STM,include both the sample's molecular structure and the dynamic characteristics of STM system.The Short Time Fourier Transform(STFT) is utilized to estimate the power spectral density(PSD)of the tunneling-current signals and the data's feature vector was extracted in the frequency space.The results obtained by PSD estimation reveal that spectral-space-based feature vector can distinguish the interference from power line(50 Hz),and it can explain and analyze the dynamic characteristics of STM efficiently by using a damped harmonic oscillator model.Meanwhile,the recognition is helpful in the control of the practice scanning condition of STM and the 3-D recreation for the images of STM.     

Microcosmic Observation and Conductive Mechanism Discuss of Nano-meter Diamond by Scanning Tunneling Microscope

The STM three dimensions surface shape appearance figure and scanning tunneling spectrum(STS) of nano-meter diamond are obtained by STM.IPC-205B developed by the authors.Insulator diamond films being transacted into nano-meter diamond particles,the STM three dimensions surface shape appearance figure of nano-meter diamond is gotten under a certain bias voltage.Then nano-meter diamond microstructure is observed.And the STS of nano-meter diamond is gained.Also it exhibits the energy gap breadth of nano-meter diamond.At the same time,the STS and conductive mechanism are analyzed.STM/STS studies can not only explain the spectrum study mechanism of conductive capability of nano-meter diamond and expand application field of STM,but also they may act as the important study means for nanometer crystal particles structure and energy spectrun character analyse after insulated material turns into nanometer crystal particles.     

Approach on the Mechanism of Electron Field Emission from CVD Diamond Films

The mechanism of electron field emission from CVD diamond films is investigated while analyzing its structure. The results indicate that there is some graphite in CVD diamond films and the coefficient which electrons tunneled through the diamond grains is enhanced because the electrons obtained energy from the electric field in graphite. Based on the results, a mechanism is put forward that enhancement of the electrons tunneled through diamond grains by graphite resulted in improvement electron emission from CVD diamond films. Some experimental results are well explained by the mechanism.     

THE CORRECTION TO THE DISTORTED IMAGE OF THE SCANNING TUNNELING MICROSCOPE

The reason of the STM image distortion is analyzed according to the principle of the Scanning Tunneling Microscope (STM). A physical and mathematical model is established and the numeral value solution is obtained by the computer. Finally,the STM distorted image is correctted with a satisfactory result.     

System of Scanning Tunneling Microscope

Some ideas are given about using out-clock, CPU and anti-T-net of D/A card for getting to the intelligent control of scanning voltage ,low-filter and hign-filter of STM; logarithm amplifier for tunnelling current contraction. At last, some applications and questions when it running about STM are discussed.     

Structure on Electrochromic Wox Films by Magnetron Sputtering Method

Using pure tungsten as target, WO_(x)films were deposited on ITOglass substrate by DC reactive magnetron sputtering. Through the XRD and STM methods, its crystal structure and surface microstructureare analyzed, and the relations between electrochromic properties and microstructure are discussed. The experimental results show that either in the colored or in the bleached state WO_(x)film deposited by magnetron sputtering method in such a condition is amorphous, as well as it is in the deposited state. The electrochromic action makes the color of the film change reversibly, and consequentiallyalso makes the microstructure change reversibly. The injection or extraction of Li~(+)does not make the basic structure of WO_(x)film change greatly, but makes the surface appearancedifferent, as a result, the accumulatemode of radical clusters tends to be more regular and low-energy mode.     

东北地区部分马铃薯品种遗传多样性的SSR分析

为对东北地区马铃薯品种鉴定提供分子水平上的依据,选用部分主栽品种（系）18 份,利用筛选出的18对多态性较好的马铃薯SSR引物进行扩增,对供试材料进行遗传多样性分析并构建指纹图谱。结果表明,供试材料共扩增出156个等位位点,其中146个为多态性位点,多态性比率达92.4%,扩增产物片段在100~800bp。利用STM1021、STI051、S170、S7、STI030、STPATP1和STM2023这7对引物构建了供试品种（系）的SSR指纹图谱。其中引物S7可以将18份品种（系）完全区分开。经聚类分析,在遗传相似系数0.61处,所有供试材可明显分为2个类群,其中14个品种（系）聚在一类,表明,聚类分析结果与供试材料来源有较好的一致性。从分子水平上表明供试材料的遗传基础较狭窄。     

Phenotypic characterization and nuclear microsatellite analysis reveal genomic changes and rearrangements underlying androgenesis in tetraploid potatoes (Solanum tuberosum L.)

Two (di)haploids (2n = 2x = 24) and nine tetraploids (2n = 4x = 48) obtained from Solanum tuberosum through anther culture were characterized for nDNA variation, phenotypic variation and nuclear microsatellite polymorphism. Androgenic (di)haploids were also characterized for late blight resistance. The (di)haploid C-13 was derived from Indian tetraploid potato cv. Kufri Chipsona-2, while D4 from TPS (true potato seed) parental line JTH/C-107, which is an interspecific hybrid between Indian tetraploid cv. Kufri Jyoti and diploid (2n = 2x = 24) cultivated species S. phureja Juz. & Buk. IVP-35. C-13 and D4 (both male-fertile) could be distinguished from their corresponding tetraploid anther donors based on plant height, shoot number, terminal leaflet length and width, leaf ratio, anther length, pollen diameter and corolla width and radius. A complete reversal of flower color occurred in D4, and C-13 was highly resistant to late blight. Most interestingly, about 3–7% increase in nDNA content occurred in most of the anther-derived tetraploids. Both the androgenic (di)haploids and their anther donors had unique genotypes at the microsatellite loci POTM1-2, STM0015 and STM0019b. However, the nine anther-derived tetraploids shared the same allelic profiles with their anther donor JTH/C-107 at all the microsatellite loci, except at STM0019a where they were characterized by the absence of a standard donor allele (186-bp). A typical (di)haploid-specific allele was detected for the locus STWAX-2 where the standard donor alleles were replaced by a 230-bp allele in both C-13 and D4. The over-expression of microsatellite variation in D4 that also shows triallelic profiles at the microsatellite loci POTM1-2 and STM0015 can perhaps be attributed to its chimeric structure, which might have been formed through incomplete fusion of two different pro-embryos during the first steps of microspore division.     

应用STM32系统设计基于物联网的农业小气候观测传感器

为实现分布式测量的农业小气候观测系统设计,需要设计一种体积小、成本相对较低的观测传感器。设计中应用STM32系统,采用现代电子设计技术及智能化的软硬件开发,实现传感器的设计制造。结果表明,应用STM32系统进行主控单元硬件设计,及STM32系统自带的标准库函数开发固化软件,不仅功能上能够满足要求,而且设计及生产成本均较低。设计完成的一体式传感器不仅能够更好地满足农业小气候观测需求,而且较集中控制方式的农业小气候观测系统有安装维护上的优势,其体积小,而且“全无线”设计,不会影响农事活动。基于物联网的智能化传感器设计为实现分布式测量打下了基础。     

利用微卫星和线粒体DNA标记研究山羊群体间的遗传关系

本研究利用微卫星和线粒体DNA分析山羊的遗传多样性及系统进化关系,用25个微卫星位点分析了安哥拉山羊、山东莱芜黑山羊、罕山白绒山羊、太行山羊及乌珠穆沁绒山羊这5个山羊品种的遗传多样性,共祖遗传距离的UPGMA聚类表明遗传距离和地理距离是一致的,如内蒙的罕山白绒山羊和乌珠穆沁绒山羊聚到一起。利用线粒体DNA分析安哥拉山羊、山东莱芜黑山羊、鲁北白山羊、太行山羊及乌珠穆沁绒山羊,揭示这5个山羊品种分成A和C 2个支系,并进行了群体结构和群体扩张分析。通过比较2种分子标记的分析结果,发现利用微卫星来研究群体的遗传多样性及品种间的关系具有较高的准确性,而线粒体在研究群体系统进化具有一定的优势,在分析品种间关系方面可能不是理想标记。     

原子吸收光谱法测定核桃中镉的含量

采用石墨炉原子吸收法进行测定,利用微波消解技术,在硝酸介质中,磷酸二氢铵和硝酸镁为基体改进剂,以赛曼扣背景校正石墨炉原子吸收法测定核桃中的镉含量。结果表明,镉在1～10 ng/mL内,质量浓度与吸光度线性关系良好(r=0.999 4,n=5)。此方法测定快速、准确、稳定。     

Analysis of DNA Cytosine Methylation on Cotton under Salt Stress

DNA methylation,especially methylation of cytosine in eukaryotic organisms,has been implicated in gene regulation,genomic imprinting,the timing of DNA replication,and determination of chromatin structure.It was reported that 6.5% of the whole cytosine residues in the nuclear DNA in higher plants were methylated.The methylation of cytosine in plant nuclear DNA occurs usually in both CpG and CpNG sequences,and the methylation state can be maintained through the cycles of DNA replication and is likely to play an integral role in regulating gene expression.     

Testing and modal analysis on multi stage planetarygearbox housing of shield tunnelling machine

The finite element model is developed for the multi stage planetary gearbox housing in shield tunnelling machine (STM), and the the eigenvalue problem is solved by using block Lanczos method, and then the low order natural frequencies and corresponding modes are extracted. Based on the theory of experimental modal analysis, the modal testing is made for the gearbox housing by pulse excitation method. The least squares complex frequency domain (LSCF) estimation method is used to analyze the modal data, and the natural characteristics of housing is obtained. According to the modal assurance criterion (MAC), the experimental modal parameters are validated. Modal analysis shows that the experimental data is coincided with analytical results, which indicates the accuracy of the theoretical model and testing method. The coupling sympathetic vibration is disappearing between the gears train and housing, the local vibration is large at the high speed side of gearbox housing, and the torsional mode is outstanding under operating condition. The research results provide theoretical basis and experimental support for the structural optimization of the gearbox of STM.     

Study on Friction and Wear Performance of Ultra High Molecular Weight Polyethylene Plastic Composite Material

The friction and wear properties of Ultra High Molecular Weight Polyethylene(UHMW PE) composites filled with MoS 2,PTFE,carbon fiber,glass fiber and graphite are studied by using MPV-200 model friction and wear tester and caustic wear one. Experiment results show that graphite,MoS 2,PTFE reduce the friction coefficient of UHMW PE, but glass fiber increases the friction coefficient of UHMW PE, graphite not only reduces the friction coefficient of UHMW PE, but also can greatly reduce the wear of UHMW PE. At the same time, the effects of wear time,rate and load on the friction and wear characteristic of plastic alloy composite material are studied.     

Effective Thermal Conductivity of a New Material of Graphite Foam Based on Fractal Theory

The new material of graphite foam is a good thermal-conductivity material. With fractal theory, the fractal character of this novel porous material is discussed. Then a thermal-conductivity model of graphite foam is proposed. The relationship formula of effective thermal conductivity is presented by using thermal resistance method. The volume fractal dimension and effective thermal conductivity of this material are calculated. This new method for calculation is significant for porous material.     

诱导子对茶条槭悬浮细胞核酸酶的激活研究

为揭示真菌诱导子诱导茶条槭悬浮细胞发生凋亡的原因,以茶条槭悬浮细胞为材料,采用细胞形态观察、基因组DNA电泳分析以及核酸酶活性检测等手段,研究了真菌诱导子对细胞发生凋亡的影响。结果表明真菌诱导子处理的细胞,其形态结构发生变化,DNA降解成呈梯状的条带,且检测到分子量大约为50、40、41、38、34 kD的核酸酶。通过这些结果说明,茶条槭悬浮细胞在真菌诱导子诱导下发生细胞凋亡,并伴有特异核酸酶被激活。     

青檀二倍体及人工诱导的同源四倍体遗传差异的AFLP分析

为了从DNA分子水平探讨二倍体青檀(2n=2x=18)与经秋水仙素诱变获得的同源四倍体青檀(2n=4x=36)在遗传结构上的差异,本研究以2x及同源4x青檀为实验材料,利用AFLP(Amplified Fragment Length Polymorphism) 分子标记技术,对供试材料的DNA多态性及遗传距离进行分析,结果表明：经秋水仙素诱变获得的同源4x青檀与2x青檀在DNA分子遗传结构上具有显著差异,2x青檀单株间DNA多态性在大于同源4x青檀,4x青檀单株间遗传距离在总体水平上大于2x青檀。本研究结果为进一步开展青檀多倍体育种、发挥青檀多倍体的优势提供理论依据。     

组蛋白变体及组蛋白分子伴侣的研究进展

组蛋白作为核小体的基本组分,是染色质的结构和功能必需的。不同时期的染色质核小体会进行相应的组蛋白变体的组装 ,从而改变核小体的空间构象和稳定性,影响基因转录的激活或沉默,DNA 的修复等。DNA复制等生物学反应需要核小体的去组装和重新组装,需要组蛋白分子伴侣的介导, 组蛋白分子伴侣对于染色质结构稳定和基因表达调控非常重要。     

基因组非编码保守DNA序列的研究进展

摘要：随着各种模式生物基因组计划的完成和海量序列数据的积累,基因组功能注释已成为一个极大的挑战,尤其是功能性非编码保守DNA序列的注释。作为一种新型的系统进化足迹,它很可能与转录因子相互作用,直接参与基因表达调控和染色体稳定。因此,非编码保守DNA序列已经得到极大关注,并极有可能成为基因组研究的下一个浪潮。文章在总结对生物非编码保守DNA序列的认识过程的基础上, 介绍了生物非编码保守DNA序列的基本情况、主要特征和研究策略,阐述了非编码保守DNA序列的形成和作用机制, 进一步展望了非编码保守DNA序列在生物学研究中的应用前景。     

香蕉束顶病毒DNA组分6的克隆及其2个组群分离物的比较分析

对香蕉束顶病毒（BBTV）广州分离物MGH DNA组分6全序列进行了克隆及序列分析。并对来自广州、海南、台湾、澳大利亚及印度的BBTV组分6进行了分析,结果表明：BBTV组分6都含有CR-SL（stem-loopcommon regions）,CR-M（major common regions）结构等典型的特征序列。BBTV组分6的核苷酸全序列、开放阅读框（ORF）核苷酸、CR-M核苷酸序列及其氨基酸序列系统进化树结果显示,BBTV分离物可分为2个组群：亚洲组和南太平洋组。CR-M结构在2个组群间有明显的差异,南太平洋组分离物的CR-M结构中有一段不完全保守的16个核苷酸的重复序列,而在亚洲组的分离物中这个序列并不重复。对BBTV组分6蛋白质进行了二级结构预测和理化性质分析发现,这2个类群蛋白质的二级结构有差异,但是理化性质无明显差异。