阿佛曼链霉菌的~(12)C离子辐照效应及高产菌株选育；Research on Mutation Breeding of High-producing Strains from Streptomyces Avermitilis Irradiated by Ion Beam of ~(12)C~(6+)

选用12C6+离子辐照诱变阿维菌素B1a产生菌ZJAV-A1,研究其诱变效应。实验结果表明,12C6+离子辐照剂量50Gy时致死率97%,正突变率最高可达到34.2%。通过12C6+离子诱变处理,结合平板培养基及斜面培养基的正突变菌株筛选,最终获得一株稳定性良好,阿维菌素B1a组分产量稳定在4460—4588μg/ml之间,较出发菌株提高11.1%—14.7%的突变株ZJAV-Y1-203。

CSR ns级重离子束动力学研究；Dynamics Study of Attaining Heavy Ion Beam With a Scale of Nanosecond Pulse Length in CSR

采用束团在纵向相空间快速旋转的非绝热压缩方法研究了在兰州重离子加速器冷却储存环(HIRFL-CSR)上获取高能ns量级短脉冲重离子束的可行性,利用K-V包络方程对能量为250MeV/u、初始纵向束团长度为200ns、初始动量分散为5×10-4的238U72+离子束团的非绝热压缩过程进行了束流动力学模拟,给出了在束团压缩过程中束流相关参数的变化。结果表明,在CSR上可取得最短为16ns长度的238U72+离子束团,可满足用于高能量密度物理研究的50ns束团长度的要求。

~(12)C离子束辐照对酵母发酵能力的影响；Improved ethanol fermentation of a yeast mutant by C-12 ion beam irradiation

利用100MeV/u的12C6+离子束辐照酵母Saccharomyces cerevsiea YY,选育出一株高产突变菌株C03A,考察C03A发酵过程中不同温度、pH、糖汁浓度对发酵的影响。通过正交实验确定最佳发酵条件为:糖汁浓度24%、温度35℃、pH5.0。在10L发酵罐实验中,C03A发酵速率相对原始菌株高,36h发酵完全,比原始菌株缩短12h;发酵产酒率达到13.2%(V/V),比原始菌株高1.6%(V/V)。

Positive- and negative-ion matrix-assisted laser desorption/ionization mass spectrometry of saccharides

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) of oligosaccharides and polysaccharides has been investigated in detail, It is demonstrated that cationized species of oligosaccharides, [M+Na](+) and [M+K](+), are dominant products under the MALDI condition, and negative ions of oligosaccharides are not formed to any significant extent in this process, The molecular masses of polysaccharides are similarly determined by positive- and negative-ion MALDI-MS with the help of column chromatography. The distinction between positive- and negative-ion MALDI mass spectra of oligo-and polysaccharides indicates that the MALDI processes for saccharides vary with molecular mass. The matrix plays a more important role in the ionization process for oligosaccharides, while in the desorption process for polysaccharides. (C) 1998 John Wiley & Sons, Ltd.

Non-linear electronic transport in Pt nanowires deposited by focused ion beam

Electrical transport and structural properties of platinum nanowires, deposited using the focussed ion beam method have been investigated. Energy dispersive X-ray spectroscopy reveals metal-rich grains (atomic composition 31% Pt and 50% Ga) in a largely non-metallic matrix of C, O and Si. Resistivity measurements (15-300 K) reveal a negative temperature coefficient with the room-temperature resistivity 80-300 times higher than that of bulk Pt. Temperature dependent current-voltage characteristics exhibit non-linear behaviour in the entire range investigated. The conductance spectra indicate increasing non-linearity with decreasing temperature, reaching 4% at 15 K. The observed electrical behaviour is explained in terms of a model for inter-grain tunnelling in disordered media, a mechanism that is consistent with the strongly disordered nature of the nanowires observed in the structure and composition analysis.

Quasi-isochoric ion beam heating using dynamic confinement in spherical geometry for X-ray scattering experiments in WDM regime

Extreme states of matter such as Warm Dense Matter “WDM” and Dense Strongly Coupled Plasmas “DSCP” play a key role in many high energy density experiments, however creating WDM and DSCP in a manner that can be quantified is not readily feasible. In this paper, isochoric heating of matter by intense heavy ion beams in spherical symmetry is investigated for WDM and DSCP research: The heating times are long (100 ns), the samples are macroscopically large (mm-size) and the symmetry is advantageous for diagnostic purposes. A dynamic confinement scheme in spherical symmetry is proposed which allows even ion beam heating times that are long on the hydrodynamic time scale of the target response. A particular selection of low Z-target tamper and x-ray probe radiation parameters allows to identify the x-ray scattering from the target material and use it for independent charge state measurements Z* of the material under study.

Creation of damage-free ferroelectric nanocapacitors via focused ion beam milling

We present a novel method for creating damage-free ferroelectric nanostructures with a focused ion beam milling machine. Using a standard e-beam photoresist followed by a dilute acid wash, nanostructures ranging in size from 1 mu m down to 250 nm were created in a 90 nm thick lead zirconate titanate ( PZT) wafer. Transmission electron microscopy and piezoresponse force microscopy ( PFM) confirmed that the surfaces of the nanostructures remained damage free during fabrication, and showed no gallium implantation, and that there was no degradation of ferroelectric properties. In fact DC strain loops, obtained using PFM, demonstrated that the nanostructures have a higher piezoresponse than unmilled films. As the samples did not have any top hard mask, the method presented is unique as it allows for imaging of the top surface to understand edge effects in well-defined nanostructures. In addition, as no post-mill annealing was necessary, it facilitates investigation of nanoscale domain mechanisms without process-induced artefacts.

Thin film capacitor cut from single crystals using focused ion beam milling

The focused ion beam microscope (FIB) has been used to fabricate thin parallel-sided ferroelectric capacitors from single crystals of BaTiO3 and SrTiO3. A series of nano-sized capacitors ranging in thickness from similar to660 nm to similar to300 nm were made. Cross-sectional high resolution transmission electron microscopy (HRTEM) revealed that during capacitor fabrication, the FIB rendered around 20 nm of dielectric at the electrode-dielectric interface amorphous, associated with local gallium impregnation. Such a region would act electrically in series with the single crystal and would presumably have a considerable negative influence on the dielectric properties. However, thermal annealing prior to gold electrodes deposition was found to fully recover the single crystal capacitors and homogenise the gallium profile. The dielectric testing of the STO ultra-thin single crystal capacitors was performed yielding a room temperature dielectric constant of similar to300, as is the case in bulk. Therefore, there was no evidence of a collapse in dielectric constant associated with thin film dimensions.