N+和Ti+离子注入井冈霉素生产菌诱变筛选高产菌株的研究

利用N 和Ti 离子注入对井冈霉素生产菌株进行诱变选育,比较了出发菌株经过两种离子源注入后的诱变效应.初步探索使用金属离子和气体离子交替注入诱变方法,得到了较高的正突变率和突变增幅.用该方法诱变得到一株高产菌株B1-3,其产井冈霉素A组分的效价为21514,比出发菌株提高54.4%.经多次传代实验表明该菌株的遗传稳定性较好.     

氮离子注入生物絮凝剂产生菌的诱变效应研究

采用30 keV氮离子注入对生物絮凝剂产生菌进行诱变选育,研究低能氮离子对微生物的诱变效应.结果表明:FJ-7 菌株的存活率曲线为典型的"马鞍型"剂量.效应曲线.经5x1015 ions·cm-2 N 注入诱变处理,最终获得一株絮凝活性高、遗传稳定性良好的突变株NIM-192.其发酵产絮凝剂曲线表明,突变株NIM-192的菌体生长速度稍慢于原始菌株,但其絮凝活性一直高于原始菌株,絮凝率比原始菌株提高了34.26%.这很可能是离子注入菌体后所产生的生物学效应使得菌体合成更多的絮凝剂,导致絮凝活性的增强.     

氮离子注入玫瑰孢链霉菌选育达托霉素高产菌株的研究

通过离子注入技术对达托霉素产生菌玫瑰孢链霉菌(Streptomyces roseosporus)进行诱变选育,使用N 作为离子源,初步探讨N 注入对达托霉素生产菌所产生的生物学效应.通过链霉素抗性筛选法获得多株遗传稳定性较好的高产突变株,其中突变株N3-36发酵单位比出发菌株提高了26%.     

Au离子注入花生种胚深度的研究

使用金属蒸汽真空孤离子源（MEVVA源）离子注入机对花生种胚进行Au离子的注入，采用卢瑟福背散射（RBS）和X射线能谱分析（EDAX）法测量Au元素在花生种子中的深度分布，并观察注入前后的样品形貌。结果表明，由于样品表面粗糙，RBS不适于测量Au元素在花生种子中的浓度分布，而EDAX的测量则显示Au元素在花生种子的最大穿透深度可达15μm。另外本文还讨论了离子注入的诱变机理。     

离子注入对菲胁迫下的苜蓿萌发的影响

为研究离子注入对多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)修复植物的诱变效应,利用离子注入苜蓿草种,探讨了离子注入后苜蓿在不同含菲质量分数环境中的萌发率和芽根长度分布.结果发现,苜蓿萌发率随注入剂量的增大,呈“鞍形”曲线特征;以植物主根长度为诱变筛选条件,发现5×1015 c...     

有机杂质对强流双潘宁离子源弧放电的危害

本文除筒单介绍双潘宁离子源产生等离子体的物理机制外,着重介绍了在研制15cm双潘宁离子源(下称15cm源)时所遇到的,因油杂质污染而导致“弧放电衰竭”问题及其物理过程。     

用于EBIT装置的小型MEVVA源及其离子注入实验

为给上海电子束离子阱(Electron Beam Ion Traps,EBIT)装置提供低电荷离子,我们研制了小型金属蒸汽真空弧(Metal Vapor Vacuum Arc,MEVVA)离子源,可产生多种金属以及半导体材料的低电荷离子.本文介绍小型MEVVA离子源的特性及其在上海EBIT装置上的离子注入实验.实验结果显示,合理控制注入参数可以使注入并被束缚在EBIT中的离子数密度达到108～109/cm3.     

GIS-1双潘宁离子源的实验研究

一、引言传统的双潘宁离子源为了获得足够高的平均饱和离子流密度,在中间电极“喉区”处采用了几何压缩和较强的主磁场压缩来提高快电子的能量,因而供给的快电子束是密集的,“点状”的。同时,由于它还采用了强的轴向辅助磁场来约束潘宁放电等离子体,因而这种类型的双潘宁离子源的饱和离子流径向不均匀性>±30％,噪声水平>±10％。     

低能N^＋注入产色氨酸酶大肠杆菌的育种研究

利用了低能旷注入产色氨酸酶大肠杆菌Escherichia coli进行诱变选育。首先进行了离子注入条件及参数的探索,确立了以15％甘油作为保护剂,N^＋注入能量10keV,剂量13×10^14cm^-2的离子注入参数。反复筛选和连续突变后,获得高产色氨酸酶大肠杆菌,和出发菌株相比,其生物量和色氨酸酶活性均有所提高。经过发酵规模逐步扩大和酶促反应体系放大,菌体生物量可达8．2gww·L^-1,其酶法催化合成L-色氨酸的产量高达110g·L^-1。该菌继代培养遗传性能稳定,可操作性强,有很好的工业化前景。     

氮离子束注入诱变选育胞外多糖高产菌株

采用氮离子束注入胞外多糖产生菌进行诱变处理来获得胞外多糖高产菌株。氮离子注入过程采用的能量为10 keV,剂量为60×1014–140×1014cm-2。根据其存活率及突变率确定最佳的注入剂量。结果表明:菌株存活率曲线遵循氮离子注入生物效应的"马鞍型曲线",当注入剂量为120×1014cm-2时,获得了最佳的诱变效果。通过筛选和连续5次传代,获得具有良好稳定性的突变株,其多糖产量达到3.29 g/L,较出发菌株提高了19.20%,且发酵周期缩短了6 h。     

Development of New Type Ion Source of Quadrupole Type Mass Spectrometer for UF6 Analysis

A new type ion source including sample inlet pipe of quadrupole type mass spectrometer for analysis of UF₆ has been made. Fundamental characteristics of the ion source, such as pressure characteristic, flow rate, sensitivity of the ion source for UFG, inlet and evacuation characteristic were evaluated. The ion source showed good operational stability under low pressure and small flow rate, which were 1.0~2.0 Torr and 0.3~0.4 mg/h, respectively. Inlet characteristic was within 60s, evacuation characteristic to remove residual UF₆ less than 0.1% level was 15s. Sensitivity coefficient of the ion source was 0.5~1.0 Torr^-1. In consequence, it proved that the ion source had long life and memory effect was negligible small.

This ion source was also applied to measure ²³⁵U isotope ratio. Both precision and accuracy were within ±0.40% for UF₆ sample whose enrichment was more than 1.0%. It was clear that this ion source had good performances and it contributed to isotope ratio measurements with good accuracy.     

PIXE、SEM与切片技术相结合研究低能离子注入种子的浓度-深度分布

用质子激发X荧光分析和扫描电子显微镜与切片技术相结合对能量为 2 0 0keV的钒离子注入花生后的浓度 -深度分布进行了测定 ,注入剂量为 9× 10 16/cm2 。结果显示 ,钒离子注入花生后的浓度 -深度分布与离子注入金属、半导体中的分布有明显的差异 :离子的射程歧离很大 ,少数离子的射程延伸到很深的区域。这种分布特征可能与植物种子具有疏松的结构有关。     

High yield antibiotic producing mutants of Streptomyces erythreus induced by low energy ion implantation

Conidia of Streptomyces erythreus, an industrial microbe, were implanted by nitrogen ions with energy of 40–60 keV and fluence from 1 × 10¹¹ to 5 × 10¹⁴ ions/cm². The logarithm value of survival fraction had good linear relationship with the logarithm value of fluence. Some mutants with a high yield of erythromycin were induced by ion implantation. The yield increment was correlated with the implantation fluence. Compared with the mutation results induced by ultraviolet rays, mutation effects of ion implantation were obvious having higher increasing erythromycin potency and wider mutation spectrum. The spores of Bacillus subtilis were implanted by arsenic ions with energy of 100 keV. The distribution of implanted ions was measured by Rutherford Backscattering Spectrometry (RBS) and calculated in theory. The mechanism of mutation induced by ion implantation was discussed.     

低能离子注入在花生四烯酸(AA)高产菌株选育中的研究

利用低能离子束生物技术对花生四烯酸产生菌(Mortierella alpina)进行诱变选育。研究表明,在离子注入(10keV,3×1014N+/cm2)条件下,后代菌株离散程度明显高于自然分离。经连续诱变处理,最终获得一株花生四烯酸高产菌I49-N18,该菌每升培养液可得生物量26.3g,干菌体中油脂含量为33.8％,其中花生四烯酸的含量占总脂的52.36％。而其AA产量高达4.66g/L,比对照N7菌株产量提高126.2％,且继代遗传功能稳定,表明I49-N18是一株极具工业化前景的高产菌,同时证明离子注入是一种有效的诱变手段。     

Long range implantation by MEVVA metal ion source

Metal vapor vacuum are(MEVVA)source ion implantation is a new technology used for achieving long range ion impantation.It is very improtant for research and application of the ion beam modification of materials.The results show that the implanted atom diffusion coefficient increases in Mo implanted Al with high ion flux and high dose.The implanted depth is 3-11.6 times greater than that of the corresponding ion range.The ion species.doses and ion fluxes play an importnat part in the long-range implantation.Especially,thermal atom chemistry have specific effect on the long-range implatation during high ion flux implantation at transient high target temperature.     

Versatile plasma ion source with an internal evaporator

A novel construction of an ion source with an evaporator placed inside a plasma chamber is presented. The crucible is heated to high temperatures directly by arc discharge, which makes the ion source suitable for substances with high melting points. The compact ion source enables production of intense ion beams for wide spectrum of solid elements with typical separated beam currents of ∼100-150 μA for Al⁺, Mn⁺, As⁺ (which corresponds to emission current densities of 15-25 mA/cm²) for the extraction voltage of 25 kV. The ion source works for approximately 50-70 h at 100% duty cycle, which enables high ion dose implantation. The typical power consumption of the ion source is 350-400 W. The paper presents detailed experimental data (e.g. dependences of ion currents and anode voltages on discharge and filament currents and magnetic flux densities) for Cr, Fe, Al, As, Mn and In. The discussion is supported by results of Monte Carlo method based numerical simulation of ionisation in the ion source.     

Influence of Temperature on Nitrogen Ion Implantation of Ti6Al4V Alloy

1. IntroductionTi6A14V alloys have been widely applied in various fields from aircraft components, chemical prrycessing facilities to medical implants, because of itsremarkable mechanical and chemical properties suchas high strength--toweight ratio and corrosion resistance [l]. Hoal.ever, its poor hardness and inferior wearing-resistance make the applicable scope ofthis material limited [2,31. There are a few reportson the effects of nitrogen ion implantation on hardness: wearing resistance, …     

A track detector technique for determining ion source emission profiles

Solid state nuclear track detectors have been used to directly measure for an ion source the beam emission cross sections along the ion beam trajectory. Results are demonstrated for an ion source of the surface ionization type using solid source materials to obtain ¹⁴⁷Sm or ⁶Li isotopes. Cellulose nitrate LR 115 was used as the detector to register the alpha tracks from the radioactive decay of the implanted ¹⁴⁷Sm and from the ⁶Li (n, α) reaction induced by thermal neutrons in a nuclear reactor.     

氯化锂-紫外-离子束复合诱变红霉素高产菌株研究

以红霉素生产菌红色链霉菌为研究对象,探讨了氯化锂、紫外、离子束3种不同诱变方式对红色链霉菌的影响,根据后代的存活率和突变率选定合适的诱变条件：氯化锂的最优诱变浓度12%,紫外的最优诱变时间120s,离子束的最优诱变注量200×1014cm－2,然后将3种方式结合起来进行复合诱变。经复合诱变后筛选获得高产突变株E0317 1 7 26,该菌株摇瓶效价达7126μg/mL,较出发菌株E03提高了203%;经多次传代分离实验表明,该突变株遗传稳定性较好。