"Dip-Pen" nanolithography

A direct-write "dip-pen" nanolithography (DPN) has been developed to deliver collections of molecules in a positive printing mode. An atomic force microscope (AFM) tip is used to write alkanethiols with 30-nanometer linewidth resolution on a gold thin film in a manner analogous to that of a dip pen. Molecules are delivered from the AFM tip to a solid substrate of interest via capillary transport, making DPN a potentially useful tool for creating and functionalizing nanoscale devices.     

Reversible loss of gravitropic sensitivity in maize roots after tip application of calcium chelators

The application of calcium chelating agents (EDTA or EGTA) to the tips of maize roots caused a loss of gravitropic sensitivity. When the chelator was replaced with calcium chloride, gravitropic sensitivity was restored. Asymmetric application of calcium chloride near the tip of a vertical root caused curvature toward the calcium source. When the calcium was applied to the upper surface of the tip of a root oriented horizontally, the root curved upward even though control roots exhibited strong downward curvature. Application of calcium chloride to the tips of decapped roots, which are known to be gravitropically insensitive, did not restore gravitropic sensitivity. However, asymmetric application of calcium chloride near the tips of decapped roots caused curvature toward the calcium source. Calcium may play a key role in linking gravity detection to gravitropic curvature in roots.     

红松挥发性物质与松梢象危害的关系

采用自动顶空进样与GC-MS联用技术,分析了被松梢象(Pissodes nitinus Roelofs)危害的红松主梢、健康红松(Pinus koraiensis Sieb.et Zucc.)主梢以及健康红松侧梢的挥发性物质成分,共发现22种挥发性物质。无论是主梢和侧梢,松芽挥发物的成分多于松针和松皮的挥发物;健康主梢与受害主梢挥发物的种类无差异,但与红松侧梢相比,红松主梢松芽中含有7种特有的挥发性物质,即α-水芹烯;1-甲基-4(1甲基亚乙基)苯;1,1-二甲基-3-甲基-1,3-丁二炔基环丙烷;十一烷;1,7,7-三甲基-乙酸-双环庚烷;α-胡椒烯;β-荜澄茄油烯。     

Formation of nanometer-scale grooves in silicon with a scanning tunneling microscope

Grooves a few nanometers wide can be formed on a Si(111) surface with a scanning tunneling microscope when the tip is above a critical voltage. This may provide a promising approach to nanodevice fabrication. The dependence of the critical voltage on tunneling current, tip polarity, and tip material was studied with silver, gold, platinum, and tungsten tips. The results are consistent with field emission of positive and negative silicon ions. The variation of critical voltage with current is explained quantitatively by a simple tunneling equation that includes the effect of the contact potential between tip and sample.     

Polymer pen lithography

We report a low-cost, high-throughput scanning probe lithography method that uses a soft elastomeric tip array, rather than tips mounted on individual cantilevers, to deliver inks to a surface in a "direct write" manner. Polymer pen lithography merges the feature size control of dip-pen nanolithography with the large-area capability of contact printing. Because ink delivery is time and force dependent, features on the nanometer, micrometer, and macroscopic length scales can be formed with the same tip array. Arrays with as many as about 11 million pyramid-shaped pens can be brought into contact with substrates and readily leveled optically to ensure uniform pattern development.     

不同灌溉方式对苹果生长发育、产量和品质的影响

研究了起垄覆膜沟灌、树盘埋罐渗灌和树盘漫灌对苹果生长发育、产量和品质的影响。结果表明:与树盘漫灌相比,起垄覆膜沟灌和树盘埋罐渗灌能显著增加新梢和春梢的长度,极显著增加叶面积、比叶重和叶绿素含量,但3个处理的新梢粗度、单株新梢数、秋梢长度、秋梢占新梢数的比例以及产量均无显著差异;树盘埋罐渗灌明显增加了根系的数量,且以直径2mm根增加最多;起垄覆膜沟灌和树盘埋罐渗灌处理的果实品质总体上优于树盘漫灌。     

Functional group imaging by chemical force microscopy

Mapping the spatial arrangement of chemical functional groups and their interactions is of significant importance to problems ranging from lubrication and adhesion to recognition in biological systems. A force microscope has been used to measure the adhesive and friction forces between molecularly modified probe tips and organic monolayers terminating in a lithographically defined pattern of distinct functional groups. The adhesive interactions between simple CH(3)/CH(3), CH(3)/COOH, and COOH/COOH functional groups correlate directly with friction images of sample surfaces patterned with these groups. Thus, by monitoring the friction between a specifically functionalized tip and sample, one can produce friction images that display predictable contrast and correspond to the spatial distribution of functional groups on the sample surface. Applications of this chemically sensitive imaging technique are discussed.     

不同砂梨品种根系形态的研究

对爱甘水、幸水和丰水3个砂梨品种6年生盛果树不同土层内根系的总长、重量、平均直径,不同直径范围内的根长、表面积、总体积、根尖数、根叉数和根尖点等进行了比较试验,结果表明:不同土层内3个砂梨品种间根系生长状况存在明显差异。0～2mm直径的根系爱甘水、丰水多集中于20～30cm土层,而幸水则集中在40～50cm土层;3个品种大于5mm根系的重量所占比例均为最高;在0～10cm土层内爱甘水的根叉数、根尖条数和根尖点数均高于幸水和丰水,在0～20cm土层内,爱甘水的根系表面积和体积也明显高于幸水和丰水。     

Oxygen tension as a control mechanism in pollen tube rupture

The decrease in stylar pO(2) encountered by pollen as it approaches the ovary can induce bursting of pollen tube tips. Anaerobic conditions induced a high percentage of tube tip bursting in most pollen germinated in vitro. Changes in tube tip metabolism with decreased oxygen probably sets up cell wall stress resulting in pollen tube rupture.     

利用小麦茎尖分生组织进行染色体制片的探讨

以不同倍性染色体小麦种质为材料,探讨通过生长点分生组织进行染色体制片,获得理想染色体图形的方法.结果表明,自然条件下,上午9:00-10:00,切取幼苗基部分蘖节约2 cm,剥离茎外部组织,立即放入有冰水混合物的试管中,试管在0～1℃冰水中处理24～30h,之后将茎尖组织转入装有卡诺氏固定液(95％酒精∶冰醋酸=3∶1...     

棉花茎尖农杆菌转化体系的建立

[目的]建立高效的以草甘膦为选择剂的棉花茎尖农杆菌遗传转化体系。[方法]以中棉35号、中棉27号、石远321和珂字312号4个陆地棉品种茎尖为遗传转化受体材料,采用农杆菌介导转化法,结合草甘膦筛选,探讨了影响棉花茎尖遗传转化效率的几个重要因素。[结果]棉花茎尖对草甘膦极为敏感,所有品种棉花茎尖均在60μmol／L草甘膦浓度下停止生长。对茎尖用OD600=1．0菌液浸染20min、预培养2d、恢复培养1周和共培养72h的处理能显著提高棉花遗传转化效率。对所有成活转基因棉株进行PCR检测的结果表明,所有植株均能扩增出目的基因aroA—M1 1．3kh的特定条带。[结论]该研究为进一步加速转基因棉花的产业化进程奠定基础。     

丙酯草醚对植物细胞有丝分裂的影响

[目的]探讨丙酯草醚的除草机理。[方法]以洋葱根尖为试材,探讨不同时间和不同浓度丙酯草醚对根尖分生细胞有丝分裂的影响。[结果]随着丙酯草醚处理浓度的增加,洋葱根尖有丝分裂指数逐渐下降;在同一浓度下,随着处理时间的延长,有丝分裂指数也呈下降趋势。对不同处理下的洋葱根尖细胞形态观察发现,在低浓度(0.012 5%)丙酯草醚短时间(2 h)处理下,洋葱根尖分生区中仍可见中、后、末期3种分裂状态的细胞。但在超过8 h的高浓度(0.100 0%)丙酯草醚处理下,分裂态细胞明显减少,分生区有明显较多分裂中期的细胞。[结论]丙酯草醚对根尖细胞的分裂有明显抑制作用,并使根尖细胞停滞于有丝分裂中期。     

美花石斛茎尖细胞分裂节律研究初报

采集不同季节、不同时间段的美花石斛茎尖,用品红染色,压片后显微观察,计算茎尖细胞的分裂指数。结果表明,美花石斛茎尖细胞的日分裂高峰为9：00（分裂指数3．3×10^-4）,月分裂高峰为5月。     

利用下端腐蚀法制备纳米级STM探针

在深入分析电化学腐蚀原理的基础上,发现了一种提高针尖的尖锐程度的新方法,即:利用下端腐蚀方法得到了比传统的上端腐蚀方法更尖锐的针尖.通过对腐蚀电压、腐蚀溶液浓度、切断时间的研究和分析,总结出下端腐蚀法制备纳米级STM探针的最佳综合条件;并通过对前人方案的修改和完善,研制了一套自动控制切断电路装置,该电路装置可以任意设置切断条件,以此得到不同粗细的针尖;最后将据此制作的纳米级针尖成功地应用于Unisoku-STM仪器的扫描,得到了清晰、稳定的原子级分辨Bi(0001)图像.     

Topographic and magnetic-sensitive scanning tunneling microscope study of magnetite

The topographic and magnetic surface structure of a natural single crystal of magnetite (Fe(3)0(4)), a common mineral, has been studied from the submicrometer scale down to the atomic scale with a scanning tunneling microscope having nonmagnetic tungsten as well as ferromagnetic iron probe tips. Several different (001) crystal planes were imaged to atomic resolution with both kinds of tips. A selective imaging of the octahedrally coordinated Fe B-sites in the Fe-O planes, and even a selective imaging of the different magnetic ions Fe(2+) and Fe(3+), has been achieved, demonstrating for the first time that magnetic imaging can be realized at the atomic level.     

Developmental Characteristics and Cinnamic Acid Resistance of Root Border Cells in Cucumber and Figleaf Gourd Seedlings

Root border cells （RBCs） originate from the root tip epidermis and surround the root apices. In this study, we evaluated the developmental characteristics and the roles of RBCs in protection of root apices of cucumber and ifgleaf gourd seedlings from CA toxicity. The formation of RBCs and the emergence of the root tip occurred almost simultaneously in root apices of cucumber and ifgleaf gourd seedlings. CA ranging from 0 to 0.25 mol L-1 inhibited root elongation and decreased root cell viability in the root tip, moreover the inhibitory effects of CA were more signiifcant in the CA-sensitive cucumber than in the CA-tolerant ifgleaf gourd. Removal of RBCs from root tips led to more severe CA induced inhibition of root elongation and decline in root cell viability. Increasing CA levels and treatment time decreased the relative viability of attached and detached RBCs. CA also induced a thicker mucilage layer surrounding attached RBCs of both species. Additionally, a signiifcantly higher relative cell viability of attached RBCs and thicker mucilage layers were observed in ifgleaf gourd. These results suggest that RBCs play an important role in protecting root tips from CA toxicity.     

木薯根尖染色体的观察技术

[目的]探索制作木薯二倍体根尖压片技术,为多倍体的鉴定提供参考。[方法]以木薯品种华南124的根尖为试材,在恒温水浴中用1 mol/L HCl溶液处理,进行细胞解离,并进行11~15 min的时间梯度试验以寻找最佳解离时间。通过木薯根尖染色体的解离观察试验,探讨了木薯根尖染色体(二倍体)的观察方法。[结果]木薯根尖的最佳取材时间在雨后或头天浇水第2天上午9∶00~10∶00。解离时间梯度试验表明,解离13 min可达到木薯的最佳解离效果。通过比较4种染色试剂(I-IK染液、改良苯酚品红、番红染液和醋酸洋红)的染色效果选出的最佳试剂为改良苯酚品红。[结论]该研究为木薯多倍体的直接鉴定提供了新方法。     

Significance of enzymatically catalyzed exchange reactions in chemotherapy

1) 3-Acetyl pyridine has been found to be quite toxic when administered to mice. Simultaneous administration of nicotinamide or DPN protects against the toxicity of acetyl pyridine. Nicotinic acid and tryptophan do not protect animals from the lethal effects of the compound. 2) Nicotinamide inhibits the formation of the 3-acetyl pyridine analog of DPN from acetyl pyridine and DPN in mouse brain homogenates. Nicotinic acid has no inhibitory effect on analog synthesis. 3) Administration of acetyl pyridine results in a fourfold increase in the DPN level of the lever. No acetyl pyridine analog of DPN is found in the liver after injection of the antimetabolite. 4) Injection of acetyl pyridine into tumor mice results in the formation of the acetyl pyridine analog of DPN in the neoplastic tissues. A decrease in DPN concentration is associated with the analog synthesis. The DPN analog has been isolated from tumor tissue and identified. 5) The results are discussed with respect to the significance of enzymatically catalyzed exchange reactions in chemotherapy.     

甘薯茎尖超低温保存技术研究

本试验采用包埋玻璃化法超低温冷冻技术保存徐薯18号的茎尖,结果表明,当剥取茎尖大小为1.0~1.5 mm,玻璃化处理时间为90 min时,茎尖存活率达85%以上。     

春石斛根端染色体制片技术的优化

为优化春石斛染色体制片技术体系,以春石斛组培苗根为材料,研究根端长度、预处理方法和酸解时间对制片的影响,结果表明,春石斛根端染色体制片时取根尖长度为1.0cm,在8-羟基喹啉和饱和对二氯苯的混合液中预处理4h,用1mol/L的盐酸在常温(25℃)下解离18min时制片效果佳,染色体形态清楚,易于观察。