~(17)B的晕结构特征

实验利用束流衰减法测量了43.7AMeV丰中子核17B与C靶反应的总截面σR=(1724±93)mb.用零程Glauber计算,假定17B具有核芯15B和两个价中子结构,输入GG和GO密度分布,计算的激发函数曲线与该实验数据很好符合,输入描述稳定核双参数Fermi密度分布,不能得到与实验数据符合的结果,表明17B是核芯15B+2n的假定是合理的.并且中子密度分布表现较大空间扩展-晕结构特征.

~(28)Si+~(12)C中的两体反应与全熔合反应

利用ΔE E望远镜系统测量了 1 56 3MeV2 8Si+ 12 C反应 (近对称系统 )中出射的Z =4— 1 4的产物元素的能谱和角分布 ,并由此给出了这些产物的胁变截面图 .从理论上计算了Z =4— 1 1产物的实验室系最可几动能分布E1(θ)和各元素的质心系的总动能分布Et(Z) ,指出了这些产物主要来自系统的两体反应过程 .还给出了该反应系统的全熔合截面值为 (980± 68)mb ,并指出从低能数据外推到此能量下的全熔合截面值与实验值之差主要归因于两体过程 .

The properties of halo structure for B-17

The total reaction cross section (1724 +/- 93 mb) of B-17 at the energy of 43.7 A MeV on C target has been measured by using the transmission method at the Radioactive Ion Beam Line in Lanzhou (RIBLL). Assuming B-17 consists of a core B-15 plus two halo neutrons, the total cross section of B-17 on C target was calculated with the zero-range Glauber model, where double Gaussian density distributions and Gaussian plus HO density distributions were used. It can fit the experimental data very well. The characteristic of halo structure for B-17 was found with a large diffusion of the neutrons density distribution.

Projectile fragmentation of Kr-86 at 64 MeV/nucleon

We measured fragmentation cross sections produced using the primary beam of Kr-86 at 64 MeV/nucleon on Be-9 and Ta-181 targets. The cross sections were obtained by integrating the momentum distributions of isotopes with 25 <= Z <= 36 measured using the RIPS fragment separator at RIKEN. The cross-section ratios obtained with the Ta-181 and Be-9 targets depend on the fragment masses, contrary to the simple geometrical models. We compared the extracted cross sections to EPAX; an empirical parametrization of fragmentation cross sections. Predictions from current EPAX parametrization severely overestimate the production cross sections of very neutron-rich isotopes. Attempts to obtain another set of EPAX parameters specific to the reaction studied here to extrapolate the neutron-rich nuclei more accurately have not been very successful, suggesting that accurate predictions of production cross sections of nuclei far from the valley of stability require information of nuclear properties that are not present in EPAX.

Neutron-Proton Asymmetry Dependence of Spectroscopic Factors in Ar Isotopes

Spectroscopic factors have been extracted for proton-rich Ar-34 and neutron-rich Ar-46 using the (p, d) neutron transfer reaction. The experimental results show little reduction of the ground state neutron spectroscopic factor of the proton-rich nucleus Ar-34 compared to that of Ar-46. The results suggest that correlations, which generally reduce such spectroscopic factors, do not depend strongly on the neutronproton asymmetry of the nucleus in this isotopic region as was reported in knockout reactions. The present results are consistent with results from systematic studies of transfer reactions but inconsistent with the trends observed in knockout reaction measurements.

Neutron spectroscopic factors of Ar-34 and Ar-46 from (p,d) transfer reactions

Single-neutron-transfer measurements using (p,d) reactions have been performed at 33 MeV per nucleon with proton-rich Ar-34 and neutron-rich Ar-46 beams in inverse kinematics. The extracted spectroscopic factors are compared to the large-basis shell-model calculations. Relatively weak quenching of the spectroscopic factors is observed between Ar-34 and Ar-46. The experimental results suggest that neutron correlations have a weak dependence on the asymmetry of the nucleus over this isotopic region. The present results are consistent with the systematics established from extensive studies of spectroscopic factors and dispersive optical-model analyses of Ca40-49 isotopes. They are, however, inconsistent with the trends obtained in knockout-reaction measurements.

Isospin diffusion and equilibration for Sn plus Sn collisions at E/A=35 MeV

Equilibration and equilibration rates have been measured by colliding Sn nuclei with different isospin asymmetries at beam energies of E/A = 35 MeV. Using the yields of mirror nuclei of Li-7 and Be-7, we have studied the diffusion of isospin asymmetry by combining data from asymmetric Sn-112 + Sn-124 and Sn-124 + Sn-112 collisions with those from symmetric Sn-112 + Sn-112 and Sn-124 + Sn-124 collisions. We use these measurements to probe isospin equilibration in central collisions where nucleon-nucleon collisions are strongly blocked by the Pauli exclusion principle. The results are consistent with transport theoretical calculations that predict a degree of transparency in these collisions, but inconsistent with the emission of intermediate mass fragments by a single chemically equilibrated source. Comparisons with quantum molecular dynamics calculations are consistent with results obtained at higher incident energies that provide constraints on the density dependence of the symmetry energy.

CONSTRAINTS ON THE DENSITY DEPENDENCE OF THE SYMMETRY ENERGY

Collisions involving Sn-112 and Sn-124 nuclei have been calculated with the ImQMD transport model in order to place constraints on the density dependences of the nuclear symmetry energy. Consistent constraints on the symmetry energy at sub-saturation density have been obtained by comparing these transport calculations to measurements of isospin diffusion and to the ratios of neutron and proton spectra. New isospin diffusion results from E/A = 35 MeV are also presented.

八单元一维位置灵敏雪崩室

In the experiment of nuclear reaction, it is important to measure the mass, charge, energy and emitted direction of particles. For multiparameter measurement, we must use a detector or a group of detectors which can give the time, energy, and position information. The Large Area position sensitive Ionization Chamber(LAIC) is one of the eight experiment terminals of HIRFL. It is built for researching nuclear reactions from low energy to intermediate energy. It is an excellent equipment for energy measurements and atomic number identification of emitted fragments in this energy region. It is also designed to give the time and position information of the emitted fragments by itself. Obviously, an IC can not supply a good timing signal. Moreover, the mechanical installation is different from the original design by some other reasons. In this case, it is not enough to obtain the correct direction information of the emitted fragments. To obtain good timing signals and the correct direction information, some modifications must be made. It is well known that a PPAC can give us excellent timing signals. It also can be easily built as a position sensitive detector. For this reason, a specially designed PPAC is installed in the entrance of the LAIC. For the different purposes, two types of PPACs were designed and tested. Both are OCTPSACs (OCTunit one dimension Position Sensitive Avalanche Counter). In this paper, both OCTPSACs will be introduced. Based on the requirements of the LAIC, the OCTPSACs consist of eight position sensitive PPACs. Each PPAC has an anode and a cathode. In both cases, the sizes are same. But different type of cathodes are used. In one type of OCTPSAC, its cathode is made of wire plane. It consists of gold-plated tungsten wires with the diameter of 20μm, spaced 0.5 mm apart from each other. The anode is a mylar foil which was evaporated by gold layer with the thickness of 50μg/cm~2 mounted on a printed plate in the shape of rectangle. the thickness of mylar foil is 1.5μm. The gap between anode and cathode is 3mm. The performance of the OCTPSAC has been tested by using a ~(252)Cf source in flowing isobutylene gas at the pressure of 3.4mb. The intrinsic time resolution of 289ps and position resolution of 2 mm have been obtained. In another type of OCTPSAC, the cathode is made of mylar foil, which is composed of gold strip by vacuume evaporation method with a special mask on the mylar foil. The thickness and the width of the gold strip is 50μg/cm~2 and 1.7mm. The strips are spaced 0.3 mm apart from each other. The anode is the same as the former type. We have obtained the time resolution of 296ps and position resolution of 2mm by using ~(241)Am-a source when the gas pressure is 6 mb and high voltage is 600V. The working gas is heptane

大豆连作及其根茬腐解物对大豆根系分泌物中酚酸类物质的影响

通过收集正茬、重茬7年、重茬7年并经MB-生物制剂调控的大豆根系分泌物和加入根茬腐解物(20gkg-1土)的正茬、重茬、调控的大豆根系分泌物,采用高效液相色谱检测方法,以对羟基苯甲酸、香草酸、香草醛、苯甲酸、阿魏酸5种酚酸类物质作为标准物质,对根系分泌物进行了检测。结果表明在正茬、重茬、调控根系分泌物中分别检测到了3种、5种、3种上述各标准物质,并且检测到的各物质的量为重茬>调控>正茬。在加入根茬腐解物的条件下,正茬和调控处理的根系分泌物中酚酸的种类和数量均有所增加。在重茬加根茬处理的根系分泌物中同样检测到了上述5种酚酸物质,并且各物质的量也有一定程度的增加。

大豆连作及其根茬腐解物对大豆根系分泌物中异黄酮类物质—黄豆甙元(daidzein)的影响

本试验通过收集正茬、重茬7年、重茬7年并经MB-生物制剂调控和加入根茬腐解物(20g kg-1土)的正茬、重茬、调控的大豆根系分泌物,采用高效液相色谱检测方法,对根系分泌物中的大豆异黄酮—黄豆甙元(daidze in)进行了检测。结果在正茬根系分泌物中没有检测到该物质,在重茬、调控根系分泌物中检测到了该物质,其检测出的量为重茬>调控。在加入根茬腐解物的各处理的根系分泌物中均检测到了大豆异黄酮,其检测出的量为重茬>正茬>调控。加入根茬腐解物的处理与不加根茬腐解物的相应的处理相比,在其根系分泌物中检测到的大豆异黄酮的量均有显著提高。

Simultaneous determination of methylene blue and new methylene blue by slab optical waveguide spectroscopy and artificial neural networks

A slab optical waveguide (SOWG) has been used for study of adsorption of both methylene blue (MB) and new methylene blue (NMB) in liquid-solid interface. Adsorption characteristics of MB and NMB on both bare SOWG and silanized SOWG by octadecyltrichlorosilane (ODS) were compared. The simultaneous determinations of both MB and NMB were explored by flow injection SOWG spectrophotometric analysis and artificial neural networks (ANNs) for the first time. Concentrations of MB and NMB were estimated simultaneously with the ANNs. Results obtained with SOWG were compared with those got by conventional UV-visible spectrophotometry. (C) 2003 Elsevier Science B.V All rights reserved.

杀虫防病种衣剂的研制及防效初报

筛选了具有较强生防能力的亲和内生细菌2株,并分离了白僵菌3株、绿僵菌2株,在此基础上对其与克百威和烯唑醇复配的可能性进行了研究,并进行了大田防治玉米土传病虫害的试验。结果表明:生防菌可以与化学农药复配;复配而成的含克.唑5%种衣剂MB对玉米土传病虫害有一定的防效作用。

Au nanoparticles grafted sandwich platform used amplified small molecule electrochemical aptasensor

We report a sensitively amplified electrochemical aptasensor using adenosine triphosphate (ATP) as a model. ATP is a multifunctional nucleotide thatis most important as a "molecular currency" of intracellular energy transfer. In the sensing process, duplexes consisting of partly complementary strand (PCS1), ATP aptamer (ABA) and another partly complementary strand (PCS2) were immobilized onto Au electrode through the 5'-HS on the PCS1. Meanwhile, PCS2 was grafted with the Au nanoparticles (AuNPs) to amplify the detection signals. In the absence of ATP, probe methylene blue (MB) bound to the DNA duplexes and also bound to guanine bases specifically to produce a strong differential pulse voltammetry (DPV) signal. But when ATP exists, the ABA-PCS2 or ABA-PCS1 part duplexes might be destroyed, which decreased the amount of MB on the electrode and led to obviously decreased DPV signal.

Methylene blue as an indicator for sensitive electrochemical detection of adenosine based on aptamer switch

In this paper, a simple, label-free and regenerative method was proposed to study the interaction between aptamer and small molecule by using methylene blue (MB+) as an electrochemical indicator. A thiolated capture probe containing twelve bases was firstly self-assembled on gold electrode by gold-sulfur affinity. Aptamer probe containing thirty two bases, which was designed to hybridize with capture DNA sequence and specifically recognize adenosine, was then immobilized on the electrode surface by hybridization reaction. MB+ was abundantly adsorbed on the aptamer probe by the specific interaction between MB+ and guanine base in aptamer probe. MB+-anchored aptamer probe can be forced to dissociate from the sensing interface after adenosine triggered structure switching of the aptamer. The peak current of MB+ linearly decreased with the concentration of adenosine over a range of 2 x 10 (8)- x 10 (6) M with a detection limit of 1 x 10 (8) M. In addition, we examined the selectivity of this electrochemical biosensor for cytidine, uridine and guanosine that belonged to the nucleosides family and possessed 1 similar structure with adenosine.